Publications
In this page you can find our publications, from latest to oldest.
2010
35.
Viganò, M.; Ragaini, F.; Buonomenna, M. G.; Lariccia, R.; Caselli, A.; Gallo, E.; Cenini, S.; Jansen, J. C.; Drioli, E.
In: ChemCatChem, vol. 2, no. 9, pp. 1150-1164, 2010, ISSN: 18673880.
@article{Viganò20101150,
title = {Catalytic Polymer Membranes under Forcing Conditions: Reduction of Nitrobenzene by CO/H2O Catalyzed by Ruthenium Bis(arylimino)acenaphthene Complexes},
author = {M. Viganò and F. Ragaini and M. G. Buonomenna and R. Lariccia and A. Caselli and E. Gallo and S. Cenini and J. C. Jansen and E. Drioli},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79957725819&doi=10.1002%2fcctc.201000044&partnerID=40&md5=51ab1d24b713613f002455a649557a32},
doi = {10.1002/cctc.201000044},
issn = {18673880},
year = {2010},
date = {2010-01-01},
journal = {ChemCatChem},
volume = {2},
number = {9},
pages = {1150-1164},
abstract = {Polymeric membranes embedding a metal complex have been previously employed as reusable catalysts under relatively mild conditions. Herein, the first example of a polymeric catalytic membrane employed under very forcing conditions (160°C and 5 MPa CO) is reported. The reaction investigated was the reduction of nitrobenzene to aniline by CO/H2O, catalyzed by ruthenium bis(arylimino)acenaphthene (Ar-BIAN) complexes. To better retain the complex in the membrane, a modified ligand, with long alkyl chains in the para positions of the aryl rings, was prepared. Among several polymers tested as membranes, PEEK-WC, a modified polyether ether ketone, gave the best results. Attempts to embed the ligand only in the membrane and functionalize it with the metal later, analogously to the in situ generation of the active species practiced for the homogeneous system, failed and it was necessary to synthesize new complexes that could be reduced under the reaction conditions. Best results were obtained using [Ru(Ar-BIAN)(CO)2Cl2]+Et3N. During the reaction, the complex is transformed into a mixture of [Ru3(CO)12] and a reduced form of the ligand, Ar-BIANH2. The latter was independently prepared and shown to be able to reduce nitrobenzene even in the absence of any metal. A new kind of support was designed to allow the placing of the membrane in a stirred autoclave. Using only water as solvent, no metal or ligand leaching was detected and several recycles were performed. All employed membranes were thoroughly characterized by different techniques. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Polymeric membranes embedding a metal complex have been previously employed as reusable catalysts under relatively mild conditions. Herein, the first example of a polymeric catalytic membrane employed under very forcing conditions (160°C and 5 MPa CO) is reported. The reaction investigated was the reduction of nitrobenzene to aniline by CO/H2O, catalyzed by ruthenium bis(arylimino)acenaphthene (Ar-BIAN) complexes. To better retain the complex in the membrane, a modified ligand, with long alkyl chains in the para positions of the aryl rings, was prepared. Among several polymers tested as membranes, PEEK-WC, a modified polyether ether ketone, gave the best results. Attempts to embed the ligand only in the membrane and functionalize it with the metal later, analogously to the in situ generation of the active species practiced for the homogeneous system, failed and it was necessary to synthesize new complexes that could be reduced under the reaction conditions. Best results were obtained using [Ru(Ar-BIAN)(CO)2Cl2]+Et3N. During the reaction, the complex is transformed into a mixture of [Ru3(CO)12] and a reduced form of the ligand, Ar-BIANH2. The latter was independently prepared and shown to be able to reduce nitrobenzene even in the absence of any metal. A new kind of support was designed to allow the placing of the membrane in a stirred autoclave. Using only water as solvent, no metal or ligand leaching was detected and several recycles were performed. All employed membranes were thoroughly characterized by different techniques. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
34.
Hagar, M.; Ragaini, F.; Monticelli, E.; Caselli, A.; MacChi, P.; Casati, N.
Chiral cyclopropylamines in the synthesis of new ligands; First asymmetric Alkyl-BIAN compounds Journal Article
In: Chemical Communications, vol. 46, no. 33, pp. 6153-6155, 2010, ISSN: 13597345.
@article{Hagar20106153,
title = {Chiral cyclopropylamines in the synthesis of new ligands; First asymmetric Alkyl-BIAN compounds},
author = {M. Hagar and F. Ragaini and E. Monticelli and A. Caselli and P. MacChi and N. Casati},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955811534&doi=10.1039%2fc0cc00977f&partnerID=40&md5=0a93a7981d877bfe82db076360a7313b},
doi = {10.1039/c0cc00977f},
issn = {13597345},
year = {2010},
date = {2010-01-01},
journal = {Chemical Communications},
volume = {46},
number = {33},
pages = {6153-6155},
publisher = {Royal Society of Chemistry},
abstract = {The synthesis of new pinene-derived chiral cyclopropylamines and their use in the synthesis of the first asymmetric Alkyl-BIAN ligands (Alkyl-BIAN = bis-(alkylimino)acenaphthenequinone) are reported. © 2010 The Royal Society of Chemistry.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The synthesis of new pinene-derived chiral cyclopropylamines and their use in the synthesis of the first asymmetric Alkyl-BIAN ligands (Alkyl-BIAN = bis-(alkylimino)acenaphthenequinone) are reported. © 2010 The Royal Society of Chemistry.
33.
Caselli, A.; Buonomenna, M. G.; Baldironi, F.; Laera, L.; Fantauzzi, S.; Ragaini, F.; Gallo, E.; Golemme, G.; Cenini, S.; Drioli, E.
In: Journal of Molecular Catalysis A: Chemical, vol. 317, no. 1-2, pp. 72-80, 2010, ISSN: 13811169.
@article{Caselli201072,
title = {From homogeneously to heterogeneously catalyzed cyclopropanation reactions: New polymeric membranes embedding cobalt chiral schiff base complexes},
author = {A. Caselli and M. G. Buonomenna and F. Baldironi and L. Laera and S. Fantauzzi and F. Ragaini and E. Gallo and G. Golemme and S. Cenini and E. Drioli},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-72049103665&doi=10.1016%2fj.molcata.2009.10.024&partnerID=40&md5=14886fa809b924738dd8cf2f0b3a6a01},
doi = {10.1016/j.molcata.2009.10.024},
issn = {13811169},
year = {2010},
date = {2010-01-01},
journal = {Journal of Molecular Catalysis A: Chemical},
volume = {317},
number = {1-2},
pages = {72-80},
abstract = {In this paper we report the preparation of catalytic polymeric membranes having the complex [(N,N′-bis(3-tert-butyl-5-(heptadecafluorooctyl)salicylidene)-trans-1,2-cyclohexanediamine)Co] embedded into Hyflon AD60X, PES and PSf and their use in the cyclopropanation reaction of olefins with ethyl diazoacetate (EDA). A study of the reaction in the homogeneous phase was also performed. The kinetics of the cyclopropanation reaction is first-order in the diazoacetate and the catalyst and zero order in the olefin, but we observed a more complex dependence on the additive, NMI (N-methylimidazole). The positive effect of the additive is completely reversed at NMI concentration higher than 6·10-2 M. © 2009 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper we report the preparation of catalytic polymeric membranes having the complex [(N,N′-bis(3-tert-butyl-5-(heptadecafluorooctyl)salicylidene)-trans-1,2-cyclohexanediamine)Co] embedded into Hyflon AD60X, PES and PSf and their use in the cyclopropanation reaction of olefins with ethyl diazoacetate (EDA). A study of the reaction in the homogeneous phase was also performed. The kinetics of the cyclopropanation reaction is first-order in the diazoacetate and the catalyst and zero order in the olefin, but we observed a more complex dependence on the additive, NMI (N-methylimidazole). The positive effect of the additive is completely reversed at NMI concentration higher than 6·10-2 M. © 2009 Elsevier B.V. All rights reserved.
32.
Carlucci, L.; Ciani, G.; Maggini, S.; Proserpio, D. M.; Ragaini, F.; Gallo, E.; Ranocchiari, M.; Caselli, A.
In: Journal of Porphyrins and Phthalocyanines, vol. 14, no. 9, pp. 804-814, 2010, ISSN: 10884246.
@article{Carlucci2010804,
title = {Synthesis and characterization of new tetra-substituted porphyrins with exo-donor carboxylic groups as building blocks for supramolecular architectures. Catalytic and structural studies of their metalated derivatives},
author = {L. Carlucci and G. Ciani and S. Maggini and D. M. Proserpio and F. Ragaini and E. Gallo and M. Ranocchiari and A. Caselli},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650156835&doi=10.1142%2fS1088424610002641&partnerID=40&md5=52a48fc16f96c02aa88779d02c30f58b},
doi = {10.1142/S1088424610002641},
issn = {10884246},
year = {2010},
date = {2010-01-01},
journal = {Journal of Porphyrins and Phthalocyanines},
volume = {14},
number = {9},
pages = {804-814},
publisher = {World Scientific Publishing Co. Pte Ltd},
abstract = {We report herein the synthesis of the porphyrins 5,10,15,20-tetrakis(4- carboxybiphenyl)-porphyrin (H2TCBP) and 5,10,15,20-tetrakis(4- carboxy-2,6-dimethylbiphenyl)porphyrin (H2TCDMBP) bearing diphenyl units on meso-positions, and of their cobalt and silver derivatives. The silver complexes of H2TCDMBP and of H2TCPP (H2TCPP = 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) were investigated by X-ray crystallography and their supramolecular organization elucidated. Co(TCBP) was reacted with copper formate, yielding a polymeric compound that showed a catalytic activity in the benzylic amination of hydrocarbons using arylazide as aminating agent. © 2010 World Scientific Publishing Company.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report herein the synthesis of the porphyrins 5,10,15,20-tetrakis(4- carboxybiphenyl)-porphyrin (H2TCBP) and 5,10,15,20-tetrakis(4- carboxy-2,6-dimethylbiphenyl)porphyrin (H2TCDMBP) bearing diphenyl units on meso-positions, and of their cobalt and silver derivatives. The silver complexes of H2TCDMBP and of H2TCPP (H2TCPP = 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) were investigated by X-ray crystallography and their supramolecular organization elucidated. Co(TCBP) was reacted with copper formate, yielding a polymeric compound that showed a catalytic activity in the benzylic amination of hydrocarbons using arylazide as aminating agent. © 2010 World Scientific Publishing Company.
31.
Intrieri, D.; Caselli, A.; Ragaini, F.; Cenini, S.; Gallo, E.
Ruthenium porphyrins-catalyzed atom-efficient amination of C-H bonds by arylazides Journal Article
In: Journal of Porphyrins and Phthalocyanines, vol. 14, no. 8, pp. 732-740, 2010, ISSN: 10884246.
@article{Intrieri2010732,
title = {Ruthenium porphyrins-catalyzed atom-efficient amination of C-H bonds by arylazides},
author = {D. Intrieri and A. Caselli and F. Ragaini and S. Cenini and E. Gallo},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78149419836&doi=10.1142%2fS1088424610002501&partnerID=40&md5=f99e08d5c82a6fd5a79a75001890694a},
doi = {10.1142/S1088424610002501},
issn = {10884246},
year = {2010},
date = {2010-01-01},
journal = {Journal of Porphyrins and Phthalocyanines},
volume = {14},
number = {8},
pages = {732-740},
publisher = {World Scientific Publishing Co. Pte Ltd},
abstract = {Benzylic amines are synthesized in yield up to 90% by the Ru(TPP)CO-catalyzed amination of both exocyclic and endocyclic benzylic C-H bonds. The choice of arylazides as nitrogen sources confers to the methodology a good sustainability due to the formation of molecular nitrogen as the only stoichiometric by-product. A preliminary mechanistic investigation evidenced a critical role of the hydrocarbon concentration to drive the chemoselectivity of the reaction. © 2010 World Scientific Publishing Company.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Benzylic amines are synthesized in yield up to 90% by the Ru(TPP)CO-catalyzed amination of both exocyclic and endocyclic benzylic C-H bonds. The choice of arylazides as nitrogen sources confers to the methodology a good sustainability due to the formation of molecular nitrogen as the only stoichiometric by-product. A preliminary mechanistic investigation evidenced a critical role of the hydrocarbon concentration to drive the chemoselectivity of the reaction. © 2010 World Scientific Publishing Company.
30.
Rose, E.; Gallo, E.; Raoul, N.; Bouché, L.; Pille, A.; Caselli, A.; Lequin, O.
Chiral "basket handle" binaphthyl porphyrins: Synthesis, catalytic epoxidation and NMR conformational studies Journal Article
In: Journal of Porphyrins and Phthalocyanines, vol. 14, no. 7, pp. 646-659, 2010, ISSN: 10884246.
@article{Rose2010646,
title = {Chiral "basket handle" binaphthyl porphyrins: Synthesis, catalytic epoxidation and NMR conformational studies},
author = {E. Rose and E. Gallo and N. Raoul and L. Bouché and A. Pille and A. Caselli and O. Lequin},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77957340036&doi=10.1142%2fS1088424610002483&partnerID=40&md5=b54999c3032e585f927607fbb93d8f0f},
doi = {10.1142/S1088424610002483},
issn = {10884246},
year = {2010},
date = {2010-01-01},
journal = {Journal of Porphyrins and Phthalocyanines},
volume = {14},
number = {7},
pages = {646-659},
publisher = {World Scientific Publishing Co. Pte Ltd},
abstract = {Three "basket handle" porphyrins have been prepared by condensation of tetrakis-(α,β,α,β-2-aminophenyl)porphyrin atropoisomer with 1,1′-binaphthyl, 2,2′-dimethoxy, -3,3′-dicarbonylchloride, -3,3′-diacetylchloride and -3,3′-dipropanoylchloride. The epoxidation of styrene with the three iron catalysts, obtained after metalation of the free porphyrins, occurs with good yields and moderate ee up to 54%. These porphyrins showed unexpected conformational differences, as revealed by NMR spectroscopy. In particular, variable temperature NMR studies showed that the methoxy group in one of them undergoes intermediate conformational exchange on the 1H NMR time scale at room temperature. Lowering the temperature to -50 °C revealed the presence of four states in slow exchange on the NMR time scale. These results evidence a dynamic conformational equilibrium of the binaphthyl handles that adopt different, asymmetric positions with respect to the porphyrin plane. © 2010 World Scientific Publishing Company.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Three "basket handle" porphyrins have been prepared by condensation of tetrakis-(α,β,α,β-2-aminophenyl)porphyrin atropoisomer with 1,1′-binaphthyl, 2,2′-dimethoxy, -3,3′-dicarbonylchloride, -3,3′-diacetylchloride and -3,3′-dipropanoylchloride. The epoxidation of styrene with the three iron catalysts, obtained after metalation of the free porphyrins, occurs with good yields and moderate ee up to 54%. These porphyrins showed unexpected conformational differences, as revealed by NMR spectroscopy. In particular, variable temperature NMR studies showed that the methoxy group in one of them undergoes intermediate conformational exchange on the 1H NMR time scale at room temperature. Lowering the temperature to -50 °C revealed the presence of four states in slow exchange on the NMR time scale. These results evidence a dynamic conformational equilibrium of the binaphthyl handles that adopt different, asymmetric positions with respect to the porphyrin plane. © 2010 World Scientific Publishing Company.
2009
29.
Ragaini, F.; Gasperini, M.; Cenini, S.; Arnera, L.; Caselli, A.; Macchi, P.; Casati, N.
In: Chemistry - A European Journal, vol. 15, no. 32, pp. 8064-8077, 2009, ISSN: 09476539.
@article{Ragaini20098064,
title = {Mechanistic study of the palladium - Phenanthroline catalyzed carbonylation of nitroarenes and amines: Palladium - Carbonyl intermediates and bifunctional effects},
author = {F. Ragaini and M. Gasperini and S. Cenini and L. Arnera and A. Caselli and P. Macchi and N. Casati},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-68349097180&doi=10.1002%2fchem.200801882&partnerID=40&md5=4742af83144896a58bb82f5d672ce5d0},
doi = {10.1002/chem.200801882},
issn = {09476539},
year = {2009},
date = {2009-01-01},
journal = {Chemistry - A European Journal},
volume = {15},
number = {32},
pages = {8064-8077},
abstract = {Palladium - phenanthroline complexes catalyze both the nitroarene carbonylation reaction and the amine oxidative carbonylation reaction to give, depending on the conditions, carbamates and ureas. There is evidence that the key step in both processes is the amine carbonylation. Here, we show that when the reaction is run in methanol key intermediate compounds have the general formula [Pd(RPhen)(COOMe)2] (1) (RPhen = l,10-phenanthroline or one of its substituted derivatives). The kinetics of the reaction of 1 with toluidine in the presence of a carboxylic or phosphorus acid is firstorder with respect to complex, acid, and toluidine. A CO atmosphere is also required for the reaction to proceed. Acid dimerization was shown not to be influential under the concentration conditions examined, but reaction between the acid and toluidine is not negligible and a correction has to be applied. Diphenylphosphinic acid is more effective than any carboxylic acid in promoting this reaction, as also observed under catalytic conditions. A series of equilibria and an irreversible acid-assisted proton transfer explain the observed data. Formation of an adduct between complexes of the kind 1 and CO was spectroscopically observed when RPhen = 2,9-Me2Phen. Several analogous complexes were also spectroscopically characterized and the X-ray structure of [Pd(2,9Me2Phen)Cl2(CO)] was solved. This shows an asymmetric coordination of the nitrogen ligand. Kinetic measurements were also conducted under catalytic conditions. An Eyring plot shows that the effect of the acidic promoter is to decrease the △S * value, whereas no positive effect is observed on △H*. A temperature-dependent correction for the reaction between the acid and aniline and phenanthroline present under the reaction conditions has to be applied. Comparison of the results obtained under stoichiometric and catalytic conditions strongly supports the view that 1 is involved even in the latter and that the acid is acting as a bifunctional promoter. © 2009 Wiley-VCH Verlag GmbH & Co.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Palladium - phenanthroline complexes catalyze both the nitroarene carbonylation reaction and the amine oxidative carbonylation reaction to give, depending on the conditions, carbamates and ureas. There is evidence that the key step in both processes is the amine carbonylation. Here, we show that when the reaction is run in methanol key intermediate compounds have the general formula [Pd(RPhen)(COOMe)2] (1) (RPhen = l,10-phenanthroline or one of its substituted derivatives). The kinetics of the reaction of 1 with toluidine in the presence of a carboxylic or phosphorus acid is firstorder with respect to complex, acid, and toluidine. A CO atmosphere is also required for the reaction to proceed. Acid dimerization was shown not to be influential under the concentration conditions examined, but reaction between the acid and toluidine is not negligible and a correction has to be applied. Diphenylphosphinic acid is more effective than any carboxylic acid in promoting this reaction, as also observed under catalytic conditions. A series of equilibria and an irreversible acid-assisted proton transfer explain the observed data. Formation of an adduct between complexes of the kind 1 and CO was spectroscopically observed when RPhen = 2,9-Me2Phen. Several analogous complexes were also spectroscopically characterized and the X-ray structure of [Pd(2,9Me2Phen)Cl2(CO)] was solved. This shows an asymmetric coordination of the nitrogen ligand. Kinetic measurements were also conducted under catalytic conditions. An Eyring plot shows that the effect of the acidic promoter is to decrease the △S * value, whereas no positive effect is observed on △H*. A temperature-dependent correction for the reaction between the acid and aniline and phenanthroline present under the reaction conditions has to be applied. Comparison of the results obtained under stoichiometric and catalytic conditions strongly supports the view that 1 is involved even in the latter and that the acid is acting as a bifunctional promoter. © 2009 Wiley-VCH Verlag GmbH & Co.
28.
Youssef, N. S.; El-Zahany, E.; El-Seidy, A. M. A.; Caselli, A.; Cenini, S.
In: Journal of Molecular Catalysis A: Chemical, vol. 308, no. 1-2, pp. 159-168, 2009, ISSN: 13811169.
@article{Youssef2009159,
title = {Synthesis and characterization of some transition metal complexes with a novel Schiff base ligand and their use as catalysts for olefin cyclopropanation},
author = {N. S. Youssef and E. El-Zahany and A. M. A. El-Seidy and A. Caselli and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67649502900&doi=10.1016%2fj.molcata.2009.04.004&partnerID=40&md5=83eedce924c9e18e5d5d15e4f911646b},
doi = {10.1016/j.molcata.2009.04.004},
issn = {13811169},
year = {2009},
date = {2009-01-01},
journal = {Journal of Molecular Catalysis A: Chemical},
volume = {308},
number = {1-2},
pages = {159-168},
abstract = {A novel ligand HL (1), N,2-bis(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazinecarbothioamide was synthesized through the condensation of 3-acetyl-2H-chromen-2-one and hydrazinecarbothioamide. This ligand was used to prepare new transition metal complexes of Cu(II), Ni(II) and Co(II). Characterization of the HL (1) ligand and its complexes is also reported. Mass spectra and NMR assignments for the ligand, using COSY, NOESY homonuclear and HMQC and HMBC heteronuclear correlation techniques were carried out. Electronic and magnetic moments of the complexes indicate that the geometries of the metal centers are either distorted octahedral, or square planar. The structures are consistent with the IR, UV-vis, ESR, as well as conductivity measurements. The catalytic activity of the copper complex, [HLCu2Cl3]Cl·H2O (2), in cyclopropanation reactions of unactivated olefins with ethyldiazoacetate (EDA) was studied. Cyclopropanes were obtained in high yield (up to 97%, TON up to 16,900) with moderate to good diastereoselectivities (50-91%). © 2009 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A novel ligand HL (1), N,2-bis(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazinecarbothioamide was synthesized through the condensation of 3-acetyl-2H-chromen-2-one and hydrazinecarbothioamide. This ligand was used to prepare new transition metal complexes of Cu(II), Ni(II) and Co(II). Characterization of the HL (1) ligand and its complexes is also reported. Mass spectra and NMR assignments for the ligand, using COSY, NOESY homonuclear and HMQC and HMBC heteronuclear correlation techniques were carried out. Electronic and magnetic moments of the complexes indicate that the geometries of the metal centers are either distorted octahedral, or square planar. The structures are consistent with the IR, UV-vis, ESR, as well as conductivity measurements. The catalytic activity of the copper complex, [HLCu2Cl3]Cl·H2O (2), in cyclopropanation reactions of unactivated olefins with ethyldiazoacetate (EDA) was studied. Cyclopropanes were obtained in high yield (up to 97%, TON up to 16,900) with moderate to good diastereoselectivities (50-91%). © 2009 Elsevier B.V. All rights reserved.
27.
Fantauzzi, S.; Caselli, A.; Gallo, E.
Nitrene transfer reactions mediated by metallo-porphyrin complexes Journal Article
In: Dalton Transactions, no. 28, pp. 5434-5443, 2009, ISSN: 14779226.
@article{Fantauzzi20095434,
title = {Nitrene transfer reactions mediated by metallo-porphyrin complexes},
author = {S. Fantauzzi and A. Caselli and E. Gallo},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67650500862&doi=10.1039%2fb902929j&partnerID=40&md5=bc1e8c38d49250ef9ffa4154710e3b2d},
doi = {10.1039/b902929j},
issn = {14779226},
year = {2009},
date = {2009-01-01},
journal = {Dalton Transactions},
number = {28},
pages = {5434-5443},
abstract = {Nitrene transfer reactions represent a useful methodology to synthesize in a few steps high added-value compounds used as organic intermediates. Herein, we describe the catalytic activity of metal porphyrin complexes in a wide range of reactions such as C-H hydrocarbon amination and olefin aziridination to synthesize nitrogen containing molecules. All the most important nitrene sources have been reviewed stressing the potentiality and limits of each one in the particular class of chemical transformation. © The Royal Society of Chemistry 2009.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nitrene transfer reactions represent a useful methodology to synthesize in a few steps high added-value compounds used as organic intermediates. Herein, we describe the catalytic activity of metal porphyrin complexes in a wide range of reactions such as C-H hydrocarbon amination and olefin aziridination to synthesize nitrogen containing molecules. All the most important nitrene sources have been reviewed stressing the potentiality and limits of each one in the particular class of chemical transformation. © The Royal Society of Chemistry 2009.
26.
Youssef, N. S.; El-Zahany, E.; El-Seidy, A. M. A.; Caselli, A.; Fantauzzi, S.; Cenini, S.
Synthesis and characterisation of new Schiff base metal complexes and their use as catalysts for olefin cyclopropanation Journal Article
In: Inorganica Chimica Acta, vol. 362, no. 6, pp. 2006-2014, 2009, ISSN: 00201693.
@article{Youssef20092006,
title = {Synthesis and characterisation of new Schiff base metal complexes and their use as catalysts for olefin cyclopropanation},
author = {N. S. Youssef and E. El-Zahany and A. M. A. El-Seidy and A. Caselli and S. Fantauzzi and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-64449088653&doi=10.1016%2fj.ica.2008.09.012&partnerID=40&md5=b116712613be7d8d9ed7bc50e61663e0},
doi = {10.1016/j.ica.2008.09.012},
issn = {00201693},
year = {2009},
date = {2009-01-01},
journal = {Inorganica Chimica Acta},
volume = {362},
number = {6},
pages = {2006-2014},
publisher = {Elsevier S.A.},
abstract = {New transition metal complexes of CoII, CuII, NiII and VIVO with the Schiff base, HL, 3-acetylcoumarin-N(4)-phenylthiosemicarbazone have been prepared. Characterisation of the HL ligand and its complexes is also reported. Mass spectra and NMR assignments for the ligand, using COSY, NOESY homonuclear and HMQC and HMBC heteronuclear correlation techniques were carried out. Electronic and magnetic moments of the complexes indicate that the geometries of the metal centres are either distorted octahedral, square pyramidal, square planar or tetrahedral. The structures are consistent with the IR, UV-Vis, ESR, as well as conductivity and magnetic moments measurements. Cyclopropanation reactions of unactivated olefins by ethyldiazoacetate (EDA) in the presence of LCuIICl as catalyst proceed with excellent TON (up to 9625). © 2008 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
New transition metal complexes of CoII, CuII, NiII and VIVO with the Schiff base, HL, 3-acetylcoumarin-N(4)-phenylthiosemicarbazone have been prepared. Characterisation of the HL ligand and its complexes is also reported. Mass spectra and NMR assignments for the ligand, using COSY, NOESY homonuclear and HMQC and HMBC heteronuclear correlation techniques were carried out. Electronic and magnetic moments of the complexes indicate that the geometries of the metal centres are either distorted octahedral, square pyramidal, square planar or tetrahedral. The structures are consistent with the IR, UV-Vis, ESR, as well as conductivity and magnetic moments measurements. Cyclopropanation reactions of unactivated olefins by ethyldiazoacetate (EDA) in the presence of LCuIICl as catalyst proceed with excellent TON (up to 9625). © 2008 Elsevier B.V. All rights reserved.
25.
Fantauzzi, S.; Gallo, E.; Caselli, A.; Piangiolino, C.; Ragaini, F.; Re, N.; Ceninii, S.
Rearrangement of N-Aryl-2-vinylaziridines to benzoazepines and dihydropyrroles: A synthetic and theoretical study Journal Article
In: Chemistry - A European Journal, vol. 15, no. 5, pp. 1241-1251, 2009, ISSN: 09476539.
@article{Fantauzzi20091241,
title = {Rearrangement of N-Aryl-2-vinylaziridines to benzoazepines and dihydropyrroles: A synthetic and theoretical study},
author = {S. Fantauzzi and E. Gallo and A. Caselli and C. Piangiolino and F. Ragaini and N. Re and S. Ceninii},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-58449102071&doi=10.1002%2fchem.200801148&partnerID=40&md5=2edc10fb4a07e55dba1d3d9cbd0249f2},
doi = {10.1002/chem.200801148},
issn = {09476539},
year = {2009},
date = {2009-01-01},
journal = {Chemistry - A European Journal},
volume = {15},
number = {5},
pages = {1241-1251},
abstract = {Herein we report the one-pot synthesis of several N-heterocyclic compounds by rearrangement reactions of N-aryl-2-vinylaziridines. The optimization of the synthetic methodology employed allowed us to obtain differently substituted 2,5-dihydro-1H-benzo[b]azepines in good yields and purities. The relationship between the nature of the starting N-aryl-2-vinylaziridine and the obtained N-het-erocycle was also investigated. Finally, to rationalize all the experimental results reported in this paper a theoretical study was performed that casts light on the reaction mechanism. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Herein we report the one-pot synthesis of several N-heterocyclic compounds by rearrangement reactions of N-aryl-2-vinylaziridines. The optimization of the synthetic methodology employed allowed us to obtain differently substituted 2,5-dihydro-1H-benzo[b]azepines in good yields and purities. The relationship between the nature of the starting N-aryl-2-vinylaziridine and the obtained N-het-erocycle was also investigated. Finally, to rationalize all the experimental results reported in this paper a theoretical study was performed that casts light on the reaction mechanism. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.
24.
Fantauzzi, S.; Gallo, E.; Caselli, A.; Ragaini, F.; Casati, N.; MacChi, P.; Cenini, S.
In: Chemical Communications, no. 26, pp. 3952-3954, 2009, ISSN: 13597345.
@article{Fantauzzi20093952,
title = {The key intermediate in the amination of saturated C-H bonds: Synthesis, X-ray characterization and catalytic activity of Ru(TPP)(NAr)2 (Ar = 3,5-(CF3)2C6H3)},
author = {S. Fantauzzi and E. Gallo and A. Caselli and F. Ragaini and N. Casati and P. MacChi and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67650626364&doi=10.1039%2fb903238j&partnerID=40&md5=7f25d45c47344557c70d9074e8f0f561},
doi = {10.1039/b903238j},
issn = {13597345},
year = {2009},
date = {2009-01-01},
journal = {Chemical Communications},
number = {26},
pages = {3952-3954},
publisher = {Royal Society of Chemistry},
abstract = {The complex Ru(TPP)(NAr)2 inserts a nitrene group into allylic and benzylic C-H bonds and is the key intermediate in the ruthenium porphyrin-catalyzed amination of hydrocarbons by aryl azides. © 2009 The Royal Society of Chemistry.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The complex Ru(TPP)(NAr)2 inserts a nitrene group into allylic and benzylic C-H bonds and is the key intermediate in the ruthenium porphyrin-catalyzed amination of hydrocarbons by aryl azides. © 2009 The Royal Society of Chemistry.
2008
23.
Fantauzzi, S.; Gallo, E.; Rose, E.; Raoul, N.; Caselli, A.; Issa, S.; Ragaini, F.; Cenini, S.
Asymmetric cyclopropanation of olefins catalyzed by chiral cobalt(II)-binaphthyl porphyrins Journal Article
In: Organometallics, vol. 27, no. 23, pp. 6143-6151, 2008, ISSN: 02767333.
@article{Fantauzzi20086143,
title = {Asymmetric cyclopropanation of olefins catalyzed by chiral cobalt(II)-binaphthyl porphyrins},
author = {S. Fantauzzi and E. Gallo and E. Rose and N. Raoul and A. Caselli and S. Issa and F. Ragaini and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-57849091342&doi=10.1021%2fom800556v&partnerID=40&md5=669aa52893f40ba9a202005b08b0ccc2},
doi = {10.1021/om800556v},
issn = {02767333},
year = {2008},
date = {2008-01-01},
journal = {Organometallics},
volume = {27},
number = {23},
pages = {6143-6151},
abstract = {Cobalt(II) complexes of chiral bis-binaphthyl porphyrins were prepared, and their catalytic activity in the asymmetric cyclopropanation of alkenes with ethyl diazoacetate was examined. Good yields and enantioselectivities (up to 90% ee) were observed with cis/trans ratios reaching 11:89. UV-vis and 1H NMR studies suggest that the axial nitrogen ligand N-methylimidazole could play a role in changing the enantioselectivity of the reaction. © 2008 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Cobalt(II) complexes of chiral bis-binaphthyl porphyrins were prepared, and their catalytic activity in the asymmetric cyclopropanation of alkenes with ethyl diazoacetate was examined. Good yields and enantioselectivities (up to 90% ee) were observed with cis/trans ratios reaching 11:89. UV-vis and 1H NMR studies suggest that the axial nitrogen ligand N-methylimidazole could play a role in changing the enantioselectivity of the reaction. © 2008 American Chemical Society.
22.
Caselli, A.; Cesana, F.; Gallo, E.; Casati, N.; MacChi, P.; Sisti, M.; Celentano, G.; Cenini, S.
Designing new ligands: Asymmetric cyclopropanation by Cu(I) complexes based on functionalised pyridine-containing macrocyclic ligands Journal Article
In: Dalton Transactions, no. 32, pp. 4202-4205, 2008, ISSN: 14779226.
@article{Caselli20084202,
title = {Designing new ligands: Asymmetric cyclopropanation by Cu(I) complexes based on functionalised pyridine-containing macrocyclic ligands},
author = {A. Caselli and F. Cesana and E. Gallo and N. Casati and P. MacChi and M. Sisti and G. Celentano and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-49149112419&doi=10.1039%2fb809317m&partnerID=40&md5=6389a676ed40535b9308029d8c4836c7},
doi = {10.1039/b809317m},
issn = {14779226},
year = {2008},
date = {2008-01-01},
journal = {Dalton Transactions},
number = {32},
pages = {4202-4205},
abstract = {The synthesis and characterisation of copper(i) complexes, including two crystal structures of the new chiral pyridine-containing macrocyclic ligands (PC-type), and their use as catalysts in asymmetric cyclopropanation reactions are reported. © 2008 The Royal Society of Chemistry.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The synthesis and characterisation of copper(i) complexes, including two crystal structures of the new chiral pyridine-containing macrocyclic ligands (PC-type), and their use as catalysts in asymmetric cyclopropanation reactions are reported. © 2008 The Royal Society of Chemistry.
21.
Caselli, A.; Gallo, E.; Fantauzzi, S.; Morlacchi, S.; Ragaini, F.; Cenini, S.
Allylic amination and aziridination of olefins by aryl azides catalyzed by CoII(tpp): A synthetic and mechanistic study Journal Article
In: European Journal of Inorganic Chemistry, no. 19, pp. 3009-3019, 2008, ISSN: 14341948.
@article{Caselli20083009,
title = {Allylic amination and aziridination of olefins by aryl azides catalyzed by CoII(tpp): A synthetic and mechanistic study},
author = {A. Caselli and E. Gallo and S. Fantauzzi and S. Morlacchi and F. Ragaini and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-53449100590&doi=10.1002%2fejic.200800156&partnerID=40&md5=1ff942b5ba6b06fcd124292a5d4377fc},
doi = {10.1002/ejic.200800156},
issn = {14341948},
year = {2008},
date = {2008-01-01},
journal = {European Journal of Inorganic Chemistry},
number = {19},
pages = {3009-3019},
abstract = {CoII(tpp) catalyzes the reaction of aromatic azides (ArN 3) with nonactivated olefins to yield allylic amines or aziridines in moderate-to-good yields. The chemoselectivity of the catalytic reaction is particularly high. Depending on the substrate employed, allylic amines or aziridines can be obtained. The reaction mechanism was investigated, and the reaction proceeds through reversible coordination of the aryl azide to the CoII-porphyrin complex. The often postulated "nitrene" complex is not an intermediate in this reaction. The kinetics for the allylic amination is first order in azide, Co(tpp), and olefin. For the aziridination, the kinetics is again first order in azide and catalyst, but we observed a first-order dependence of the rate on α-methylstyrene only up to an olefin concentration of 6.9 M. An inhibiting role of the competitively formed 1-(4-nitrophenyl)-5-methyl-5-phenyl-1,2,3-triazoline was identified. The triazoline was shown to reversibly coordinate to Co(tpp), which blocks the free coordination site necessary for the catalytic reaction to proceed, and is it responsible for the catalyst deactivation in the aziridination reaction of α-methylstyrene by 4-nitrophenyl azide. © Wiley-VCH Verlag GmbH & Co. KGaA, 2008.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
CoII(tpp) catalyzes the reaction of aromatic azides (ArN 3) with nonactivated olefins to yield allylic amines or aziridines in moderate-to-good yields. The chemoselectivity of the catalytic reaction is particularly high. Depending on the substrate employed, allylic amines or aziridines can be obtained. The reaction mechanism was investigated, and the reaction proceeds through reversible coordination of the aryl azide to the CoII-porphyrin complex. The often postulated "nitrene" complex is not an intermediate in this reaction. The kinetics for the allylic amination is first order in azide, Co(tpp), and olefin. For the aziridination, the kinetics is again first order in azide and catalyst, but we observed a first-order dependence of the rate on α-methylstyrene only up to an olefin concentration of 6.9 M. An inhibiting role of the competitively formed 1-(4-nitrophenyl)-5-methyl-5-phenyl-1,2,3-triazoline was identified. The triazoline was shown to reversibly coordinate to Co(tpp), which blocks the free coordination site necessary for the catalytic reaction to proceed, and is it responsible for the catalyst deactivation in the aziridination reaction of α-methylstyrene by 4-nitrophenyl azide. © Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
20.
Gallo, E.; Buonomenna, M. G.; Viganò, L.; Ragaini, F.; Caselli, A.; Fantauzzi, S.; Cenini, S.; Drioli, E.
Heterogenization of ruthenium porphyrin complexes in polymeric membranes: Catalytic aziridination of styrenes Journal Article
In: Journal of Molecular Catalysis A: Chemical, vol. 282, no. 1-2, pp. 85-91, 2008, ISSN: 13811169.
@article{Gallo200885,
title = {Heterogenization of ruthenium porphyrin complexes in polymeric membranes: Catalytic aziridination of styrenes},
author = {E. Gallo and M. G. Buonomenna and L. Viganò and F. Ragaini and A. Caselli and S. Fantauzzi and S. Cenini and E. Drioli},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-40249083352&doi=10.1016%2fj.molcata.2007.11.030&partnerID=40&md5=86e46c381a1ea2b0067e0fc0100e1e20},
doi = {10.1016/j.molcata.2007.11.030},
issn = {13811169},
year = {2008},
date = {2008-01-01},
journal = {Journal of Molecular Catalysis A: Chemical},
volume = {282},
number = {1-2},
pages = {85-91},
abstract = {In this paper we report the preparation of catalytic membranes having the complex Ru(4-(CF3)TPP)CO (1) (TPP = dianion of tetraphenylporphyrin) embedded in the perfluorinated polymer Hyflon AD60X and their use in the aziridination reaction of olefins by aryl azides. The heterogeneous membrane catalysts afforded high selectivities in aziridine (90-99%). In several cases the membrane was reused three times with a catalyst leaching ≤6% but no decrease in selectivities upon recycle was observed. © 2007 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper we report the preparation of catalytic membranes having the complex Ru(4-(CF3)TPP)CO (1) (TPP = dianion of tetraphenylporphyrin) embedded in the perfluorinated polymer Hyflon AD60X and their use in the aziridination reaction of olefins by aryl azides. The heterogeneous membrane catalysts afforded high selectivities in aziridine (90-99%). In several cases the membrane was reused three times with a catalyst leaching ≤6% but no decrease in selectivities upon recycle was observed. © 2007 Elsevier B.V. All rights reserved.
19.
Buonomenna, M. G.; Gallo, E.; Ragaini, F.; Caselli, A.; Cenini, S.; Drioli, E.
New ruthenium porphyrin polymeric membranes: Preparation and characterization Journal Article
In: Applied Catalysis A: General, vol. 335, no. 1, pp. 37-45, 2008, ISSN: 0926860X.
@article{Buonomenna200837,
title = {New ruthenium porphyrin polymeric membranes: Preparation and characterization},
author = {M. G. Buonomenna and E. Gallo and F. Ragaini and A. Caselli and S. Cenini and E. Drioli},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38049121510&doi=10.1016%2fj.apcata.2007.11.012&partnerID=40&md5=1723c716d659e2afcc2d246405a3b1c4},
doi = {10.1016/j.apcata.2007.11.012},
issn = {0926860X},
year = {2008},
date = {2008-01-01},
journal = {Applied Catalysis A: General},
volume = {335},
number = {1},
pages = {37-45},
abstract = {In this work, the ruthenium porphyrin complex Ru(4-(CF3)TPP)CO (1) (TPP = dianion of tetraphenylporphyrin) was entrapped into polymeric membranes during the phase inversion process to obtain new heterogeneous catalysts for aziridination reactions. In order to study the effect of the polymeric environment on the activity of the metallic complex, symmetric dense polymeric catalytic membranes were prepared using three different polymers: polyethersulphone (PES), polysulphone (PSf) and Hyflon AD60X. Different hydrophobicity/hydrophilicity characteristics, sorption properties and ability to retain the metallic complex characterized the catalytic polymeric membranes. On the basis of the good results compared to the other two polymers, Hyflon AD60X was selected to prepare asymmetric membranes with a skin layer on an open sublayer. The Hyflon AD60X membranes showed good catalytic activity in the aziridination reaction of α-methylstyrene by aryl azides and moreover they have been recycled without any loss in azide conversion and aziridine selectivity. © 2007 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this work, the ruthenium porphyrin complex Ru(4-(CF3)TPP)CO (1) (TPP = dianion of tetraphenylporphyrin) was entrapped into polymeric membranes during the phase inversion process to obtain new heterogeneous catalysts for aziridination reactions. In order to study the effect of the polymeric environment on the activity of the metallic complex, symmetric dense polymeric catalytic membranes were prepared using three different polymers: polyethersulphone (PES), polysulphone (PSf) and Hyflon AD60X. Different hydrophobicity/hydrophilicity characteristics, sorption properties and ability to retain the metallic complex characterized the catalytic polymeric membranes. On the basis of the good results compared to the other two polymers, Hyflon AD60X was selected to prepare asymmetric membranes with a skin layer on an open sublayer. The Hyflon AD60X membranes showed good catalytic activity in the aziridination reaction of α-methylstyrene by aryl azides and moreover they have been recycled without any loss in azide conversion and aziridine selectivity. © 2007 Elsevier B.V. All rights reserved.
2007
18.
Fantauzzi, S.; Gallo, E.; Caselli, A.; Piangiolino, C.; Ragaini, F.; Cenini, S.
The (porphyrin)ruthenium-catalyzed aziridination of olefins using aryl azides as nitrogen sources Journal Article
In: European Journal of Organic Chemistry, no. 36, pp. 6053-6059, 2007, ISSN: 1434193X.
@article{Fantauzzi20076053,
title = {The (porphyrin)ruthenium-catalyzed aziridination of olefins using aryl azides as nitrogen sources},
author = {S. Fantauzzi and E. Gallo and A. Caselli and C. Piangiolino and F. Ragaini and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37549007586&doi=10.1002%2fejoc.200700678&partnerID=40&md5=cc57144f7bb4933eb1231ad777c6d00a},
doi = {10.1002/ejoc.200700678},
issn = {1434193X},
year = {2007},
date = {2007-01-01},
journal = {European Journal of Organic Chemistry},
number = {36},
pages = {6053-6059},
abstract = {Aryl azides have been used as atom-efficient nitrene transfer reagents in the (porphyrin)ruthenium-catalyzed amination of olefins. Several azides, olefins and [Ru(porphyrin)CO] complexes were tested to investigate the scope and limits of the reaction. Quantitative yields and short reaction times were achieved by using terminal olefins and aryl azides bearing electron-withdrawing groups on the aryl moiety. The reactions were influenced by steric factors. Internally disubstituted olefins exhibited a lower reactivity and tri- and tetra-substituted olefins did not react at all. A very high turnover number (TON) for the [Ru(TPP)CO] (TPP = tetraphenylporphyrin dianion) catalyzed amination of α-methylstyrene by p-nitrophenyl azide was obtained. © Wiley-VCH Verlag GmbH & Co. KGaA, 2007.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Aryl azides have been used as atom-efficient nitrene transfer reagents in the (porphyrin)ruthenium-catalyzed amination of olefins. Several azides, olefins and [Ru(porphyrin)CO] complexes were tested to investigate the scope and limits of the reaction. Quantitative yields and short reaction times were achieved by using terminal olefins and aryl azides bearing electron-withdrawing groups on the aryl moiety. The reactions were influenced by steric factors. Internally disubstituted olefins exhibited a lower reactivity and tri- and tetra-substituted olefins did not react at all. A very high turnover number (TON) for the [Ru(TPP)CO] (TPP = tetraphenylporphyrin dianion) catalyzed amination of α-methylstyrene by p-nitrophenyl azide was obtained. © Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
17.
Piangiolino, C.; Gallo, E.; Caselli, A.; Fantauzzi, S.; Ragaini, F.; Cenini, S.
The [Ru(CO)(porphyrin)]-catalyzed synthesis of N-aryl-2-vinylaziridines Journal Article
In: European Journal of Organic Chemistry, no. 5, pp. 743-750, 2007, ISSN: 1434193X.
@article{Piangiolino2007743,
title = {The [Ru(CO)(porphyrin)]-catalyzed synthesis of N-aryl-2-vinylaziridines},
author = {C. Piangiolino and E. Gallo and A. Caselli and S. Fantauzzi and F. Ragaini and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34250622480&doi=10.1002%2fejoc.200600642&partnerID=40&md5=47334b0ff51a5f1ada1502159c71a91f},
doi = {10.1002/ejoc.200600642},
issn = {1434193X},
year = {2007},
date = {2007-01-01},
journal = {European Journal of Organic Chemistry},
number = {5},
pages = {743-750},
abstract = {[Ru(CO)(porphyrin)] complexes have been found to catalyze the direct aziridination of conjugated dienes by aryl azides with high chemoselectivity, to provide N-aryl-2-vinylaziridines. To determine the scope of the reaction, several hydrocarbons and azides were tested. The reactions between 2,3-dimethylbuta-1,3-diene and aryl azides bearing electron-withdrawing groups in the para or meta positions in their aryl moieties occur very efficiently in short times, while the selectivities of the aziridinations are governed by the steric hindrances of the double bonds, so lower yields are registered with sterically encumbered 1,4-disubstituted dienes, though it is worth noting that the aziridination of trans,trans-1,4-diphenylbuta-1,3-diene was stereospecific and that only one isomer was obtained. The aza-[3,3]-Claisen rearrangement of 2-isopropenyl-2-methyl-N-(4-nitrophenyl)aziridine to produce the corresponding 2,5-1H-benzo[b]azepine is also reported. © Wiley-VCH Verlag GmbH & Co. KGaA, 2007.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
[Ru(CO)(porphyrin)] complexes have been found to catalyze the direct aziridination of conjugated dienes by aryl azides with high chemoselectivity, to provide N-aryl-2-vinylaziridines. To determine the scope of the reaction, several hydrocarbons and azides were tested. The reactions between 2,3-dimethylbuta-1,3-diene and aryl azides bearing electron-withdrawing groups in the para or meta positions in their aryl moieties occur very efficiently in short times, while the selectivities of the aziridinations are governed by the steric hindrances of the double bonds, so lower yields are registered with sterically encumbered 1,4-disubstituted dienes, though it is worth noting that the aziridination of trans,trans-1,4-diphenylbuta-1,3-diene was stereospecific and that only one isomer was obtained. The aza-[3,3]-Claisen rearrangement of 2-isopropenyl-2-methyl-N-(4-nitrophenyl)aziridine to produce the corresponding 2,5-1H-benzo[b]azepine is also reported. © Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
2006
16.
Ragaini, F.; Cenini, S.; Gallo, E.; Caselli, A.; Fantauzzi, S.
Fine chemicals by reductive carbonylation of nitroarenes, catalyzed by transition metal complexes Journal Article
In: Current Organic Chemistry, vol. 10, no. 12, pp. 1479-1510, 2006, ISSN: 13852728.
@article{Ragaini20061479,
title = {Fine chemicals by reductive carbonylation of nitroarenes, catalyzed by transition metal complexes},
author = {F. Ragaini and S. Cenini and E. Gallo and A. Caselli and S. Fantauzzi},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33747092660&doi=10.2174%2f138527206778018249&partnerID=40&md5=6ab2c7bd7f3fa1aed500487793a12b59},
doi = {10.2174/138527206778018249},
issn = {13852728},
year = {2006},
date = {2006-01-01},
journal = {Current Organic Chemistry},
volume = {10},
number = {12},
pages = {1479-1510},
abstract = {The application of reductive carbonylation of nitroarenes to the synthesis of fine chemicals is described. The review focuses on the results reported from 1996 onwards and is mainly divided in two parts, respectively describing the intra-molecular cyclization reactions of nitroarenes bearing in the ortho position a suitable functional group and the intermolecular reactions of nitroarenes with external olefins and alkynes. Benzo-fused heterocycles such as indoles and quinolinones are obtained by the first group of reactions, whereas allylic amines, oxazines, pyrroles and indoles are the products of inter-molecular reactions. Mechanistic studies are also discussed in a separate section. © 2006 Bentham Science Publishers Ltd.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The application of reductive carbonylation of nitroarenes to the synthesis of fine chemicals is described. The review focuses on the results reported from 1996 onwards and is mainly divided in two parts, respectively describing the intra-molecular cyclization reactions of nitroarenes bearing in the ortho position a suitable functional group and the intermolecular reactions of nitroarenes with external olefins and alkynes. Benzo-fused heterocycles such as indoles and quinolinones are obtained by the first group of reactions, whereas allylic amines, oxazines, pyrroles and indoles are the products of inter-molecular reactions. Mechanistic studies are also discussed in a separate section. © 2006 Bentham Science Publishers Ltd.
15.
Cenini, S.; Gallo, E.; Caselli, A.; Ragaini, F.; Fantauzzi, S.; Piangiolino, C.
Coordination chemistry of organic azides and amination reactions catalyzed by transition metal complexes Journal Article
In: Coordination Chemistry Reviews, vol. 250, no. 11-12, pp. 1234-1253, 2006, ISSN: 00108545.
@article{Cenini20061234,
title = {Coordination chemistry of organic azides and amination reactions catalyzed by transition metal complexes},
author = {S. Cenini and E. Gallo and A. Caselli and F. Ragaini and S. Fantauzzi and C. Piangiolino},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33747052051&doi=10.1016%2fj.ccr.2005.10.002&partnerID=40&md5=44f4e831986fafb8197e27dc07fd9325},
doi = {10.1016/j.ccr.2005.10.002},
issn = {00108545},
year = {2006},
date = {2006-01-01},
journal = {Coordination Chemistry Reviews},
volume = {250},
number = {11-12},
pages = {1234-1253},
abstract = {The interaction of organic azides with transition metal complexes will be discussed with particular attention to the coordination modes of these molecules. The stoichiometric reactions of organic azides with coordinated ligands will be considered and their use in amination reactions catalyzed by transition metal complexes will be discussed in detail. The utility of these catalytic reactions for the synthesis of organic compounds will be stressed. © 2005 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The interaction of organic azides with transition metal complexes will be discussed with particular attention to the coordination modes of these molecules. The stoichiometric reactions of organic azides with coordinated ligands will be considered and their use in amination reactions catalyzed by transition metal complexes will be discussed in detail. The utility of these catalytic reactions for the synthesis of organic compounds will be stressed. © 2005 Elsevier B.V. All rights reserved.
14.
Caselli, A.; Gallo, E.; Ragaini, F.; Ricatto, F.; Abbiati, G.; Cenini, S.
Chiral porphyrin complexes of cobalt(II) and ruthenium(II) in catalytic cyclopropanation and amination reactions Journal Article
In: Inorganica Chimica Acta, vol. 359, no. 9, pp. 2924-2932, 2006, ISSN: 00201693.
@article{Caselli20062924,
title = {Chiral porphyrin complexes of cobalt(II) and ruthenium(II) in catalytic cyclopropanation and amination reactions},
author = {A. Caselli and E. Gallo and F. Ragaini and F. Ricatto and G. Abbiati and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646514856&doi=10.1016%2fj.ica.2005.11.020&partnerID=40&md5=e0ab88ecd5dfa440e11cd11a51fce72b},
doi = {10.1016/j.ica.2005.11.020},
issn = {00201693},
year = {2006},
date = {2006-01-01},
journal = {Inorganica Chimica Acta},
volume = {359},
number = {9},
pages = {2924-2932},
publisher = {Elsevier S.A.},
abstract = {We report here the syntheses of two new metal complexes (M = Co, 2; M = Ru, 3) of the chiral porphyrin TmyrtP (1) (TmyrtP = dianion of the meso-tetrakis[(1R)-apopinen-2-yl]porphyrin). Both complexes exist as a mixture of atropisomers. Complexes 2 and 3 activate aromatic azides for the amination under mild conditions of unsaturated hydrocarbons. Even though the observed ee values are low, this is the first asymmetric transfer of the nitrene residue of aryl azides to a prochiral olefin catalyzed by a transition metal complex to be reported in the literature. Complex 3 also showed a good catalytic activity in cyclopropanation reactions with ethyldiazoacetate even at low temperatures (-30 °C) but a poor diastereo- and enantioselectivity were observed. © 2005 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report here the syntheses of two new metal complexes (M = Co, 2; M = Ru, 3) of the chiral porphyrin TmyrtP (1) (TmyrtP = dianion of the meso-tetrakis[(1R)-apopinen-2-yl]porphyrin). Both complexes exist as a mixture of atropisomers. Complexes 2 and 3 activate aromatic azides for the amination under mild conditions of unsaturated hydrocarbons. Even though the observed ee values are low, this is the first asymmetric transfer of the nitrene residue of aryl azides to a prochiral olefin catalyzed by a transition metal complex to be reported in the literature. Complex 3 also showed a good catalytic activity in cyclopropanation reactions with ethyldiazoacetate even at low temperatures (-30 °C) but a poor diastereo- and enantioselectivity were observed. © 2005 Elsevier B.V. All rights reserved.
13.
Ragaini, F.; Rapetti, A.; Visentin, E.; Monzani, M.; Caselli, A.; Cenini, S.
Synthesis of indoles by intermolecular cyclization of unfunctionalized nitroarenes and alkynes, catalyzed by palladium-phenanthroline complexes Journal Article
In: Journal of Organic Chemistry, vol. 71, no. 10, pp. 3748-3753, 2006, ISSN: 00223263.
@article{Ragaini20063748,
title = {Synthesis of indoles by intermolecular cyclization of unfunctionalized nitroarenes and alkynes, catalyzed by palladium-phenanthroline complexes},
author = {F. Ragaini and A. Rapetti and E. Visentin and M. Monzani and A. Caselli and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646507094&doi=10.1021%2fjo060073m&partnerID=40&md5=015de5d029a65ec7bef69cf5a9a3d5ad},
doi = {10.1021/jo060073m},
issn = {00223263},
year = {2006},
date = {2006-01-01},
journal = {Journal of Organic Chemistry},
volume = {71},
number = {10},
pages = {3748-3753},
abstract = {Palladium-phenanthroline complexes efficiently catalyze the reaction of nitroarenes with arylalkynes and CO to give 3-arylindoles by an ortho-C-H functionalization of the nitroarene ring. Both electron-withdrawing and electron-donating substituents are tolerated on the nitroarene, except for bromide and activated chloride. Nitroarenes bearing electron-withdrawing substituents react faster, but the selectivity of the reaction depends on both polar and radical stabilization effects. Among those tested, only arylalkynes afforded indoles under the investigated conditions. The reaction mechanism was partly investigated. The kinetics is first order in nitroarene concentration and the rate-determing step of the cycle is the initial nitroarene reduction. No primary isotope effect is observed on either rate or selectivity, implying that the cyclization step is fast. © 2006 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Palladium-phenanthroline complexes efficiently catalyze the reaction of nitroarenes with arylalkynes and CO to give 3-arylindoles by an ortho-C-H functionalization of the nitroarene ring. Both electron-withdrawing and electron-donating substituents are tolerated on the nitroarene, except for bromide and activated chloride. Nitroarenes bearing electron-withdrawing substituents react faster, but the selectivity of the reaction depends on both polar and radical stabilization effects. Among those tested, only arylalkynes afforded indoles under the investigated conditions. The reaction mechanism was partly investigated. The kinetics is first order in nitroarene concentration and the rate-determing step of the cycle is the initial nitroarene reduction. No primary isotope effect is observed on either rate or selectivity, implying that the cyclization step is fast. © 2006 American Chemical Society.
2005
12.
Gasperini, M.; Ragaini, F.; Remondini, C.; Caselli, A.; Cenini, S.
The palladium-phenanthroline catalyzed carbonylation of nitroarenes to diarylureas: Effect of chloride and diphenylphosphinic acid Journal Article
In: Journal of Organometallic Chemistry, vol. 690, no. 20 SPEC. ISS., pp. 4517-4529, 2005, ISSN: 0022328X.
@article{Gasperini20054517,
title = {The palladium-phenanthroline catalyzed carbonylation of nitroarenes to diarylureas: Effect of chloride and diphenylphosphinic acid},
author = {M. Gasperini and F. Ragaini and C. Remondini and A. Caselli and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-27144494569&doi=10.1016%2fj.jorganchem.2005.03.059&partnerID=40&md5=f48e941ae556f0781aabcb03c255197e},
doi = {10.1016/j.jorganchem.2005.03.059},
issn = {0022328X},
year = {2005},
date = {2005-01-01},
journal = {Journal of Organometallic Chemistry},
volume = {690},
number = {20 SPEC. ISS.},
pages = {4517-4529},
publisher = {Elsevier},
abstract = {The application of the palladium-phenanthroline catalytic system to the carbonylation of nitrobenzene in the presence of aniline to afford diphenylurea has been investigated. The reaction is best performed with equimolar amounts of the two reagents. Use of higher concentrations of either aniline or nitrobenzene or an increase in temperature in the range 120-170 °C leads to the formation of higher amounts of azo- and azoxybenzene. The latter were found to contain exclusively the aryl moiety deriving from nitrobenzene, with no inclusion of that derived from aniline. The addition of a small amount of diphenylphosphinic acid doubles the conversion and improves the selectivity in diphenylurea, but the effect is attenuated for larger amounts of acid. Small amounts of chloride, of the order of 10-30 mol% with respect to palladium, improve both rate and selectivity, but only inhibiting effects are detected when chloride is added to the reaction mixture for the carbonylation of 2,4-dinitrotoluene to dimethyl 2,4-toluenedicarbamate. The data obtained and that previously reported in the literature has been analyzed in the context of a unifying mechanism and an explanation for some apparent contradictions has been given. © 2005 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The application of the palladium-phenanthroline catalytic system to the carbonylation of nitrobenzene in the presence of aniline to afford diphenylurea has been investigated. The reaction is best performed with equimolar amounts of the two reagents. Use of higher concentrations of either aniline or nitrobenzene or an increase in temperature in the range 120-170 °C leads to the formation of higher amounts of azo- and azoxybenzene. The latter were found to contain exclusively the aryl moiety deriving from nitrobenzene, with no inclusion of that derived from aniline. The addition of a small amount of diphenylphosphinic acid doubles the conversion and improves the selectivity in diphenylurea, but the effect is attenuated for larger amounts of acid. Small amounts of chloride, of the order of 10-30 mol% with respect to palladium, improve both rate and selectivity, but only inhibiting effects are detected when chloride is added to the reaction mixture for the carbonylation of 2,4-dinitrotoluene to dimethyl 2,4-toluenedicarbamate. The data obtained and that previously reported in the literature has been analyzed in the context of a unifying mechanism and an explanation for some apparent contradictions has been given. © 2005 Elsevier B.V. All rights reserved.
11.
Fantauzzi, S.; Gallo, E.; Caselli, A.; Ragaini, F.; Macchi, P.; Casati, N.; Cenini, S.
In: Organometallics, vol. 24, no. 20, pp. 4710-4713, 2005, ISSN: 02767333.
@article{Fantauzzi20054710,
title = {Origin of the deactivation in styrene aziridination by aryl azides, catalyzed by ruthenium porphyrin complexes. Structural characterization of a Δ2-1,2,3-triazoline RuII(TPP)CO complex},
author = {S. Fantauzzi and E. Gallo and A. Caselli and F. Ragaini and P. Macchi and N. Casati and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-26444613224&doi=10.1021%2fom050244y&partnerID=40&md5=bed5e419e68c77b16c8b0e4d36230256},
doi = {10.1021/om050244y},
issn = {02767333},
year = {2005},
date = {2005-01-01},
journal = {Organometallics},
volume = {24},
number = {20},
pages = {4710-4713},
abstract = {The reaction of Ru(TPP)CO (TPP = dianion of tetraphenylporphyrin) with 1-(p-nitrophenyl)-5-methyl-5-phenyl-1,2,3-triazoline yielded a Δ2-1,2,3-triazoline ruthenium(II) porphyrin complex, which is responsible for the catalyst deactivation in the aziridination reaction of α-methylstyrene by p-nitrophenyl azide. © 2005 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The reaction of Ru(TPP)CO (TPP = dianion of tetraphenylporphyrin) with 1-(p-nitrophenyl)-5-methyl-5-phenyl-1,2,3-triazoline yielded a Δ2-1,2,3-triazoline ruthenium(II) porphyrin complex, which is responsible for the catalyst deactivation in the aziridination reaction of α-methylstyrene by p-nitrophenyl azide. © 2005 American Chemical Society.
10.
Caselli, A.; Gallo, E.; Ragaini, F.; Oppezzo, A.; Cenini, S.
Catalytic amination reactions mediated by Co(II) Schiff base complexes Journal Article
In: Journal of Organometallic Chemistry, vol. 690, no. 8 SPEC. ISS., pp. 2142-2148, 2005, ISSN: 0022328X.
@article{Caselli20052142,
title = {Catalytic amination reactions mediated by Co(II) Schiff base complexes},
author = {A. Caselli and E. Gallo and F. Ragaini and A. Oppezzo and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-16644386063&doi=10.1016%2fj.jorganchem.2005.01.021&partnerID=40&md5=c97e585858691825b48a6eea6f2fbd9b},
doi = {10.1016/j.jorganchem.2005.01.021},
issn = {0022328X},
year = {2005},
date = {2005-01-01},
journal = {Journal of Organometallic Chemistry},
volume = {690},
number = {8 SPEC. ISS.},
pages = {2142-2148},
publisher = {Elsevier},
abstract = {Co(acacen), 1, (acacen = 2,11-dihydroxy-4,9-dimethyl-5,8-diaza-2,4,8,10- dodecatetraene dianion) was found to be a highly efficient catalyst for the allylic amination of non activated alkenes, using N-(p-toluensulfonyl) iminophenyliodinane (PhINTs) as nitrene precursor. This reactivity has been extended to the less reactive C-H bond of toluene. The effect of reaction times and of added cosolvent on yields and selectivities was investigated. Under the best conditions, allylic amines were obtained in a 40-70% isolated yield. A complex derived from the stoichiometric reaction of Co(acacen), 1, with PhINTs has been isolated and spectroscopically characterized. Such a complex, although not able to transfer its NTs moiety to alkenes, is still active in catalyzing allylic amination of cyclohexene. © 2005 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Co(acacen), 1, (acacen = 2,11-dihydroxy-4,9-dimethyl-5,8-diaza-2,4,8,10- dodecatetraene dianion) was found to be a highly efficient catalyst for the allylic amination of non activated alkenes, using N-(p-toluensulfonyl) iminophenyliodinane (PhINTs) as nitrene precursor. This reactivity has been extended to the less reactive C-H bond of toluene. The effect of reaction times and of added cosolvent on yields and selectivities was investigated. Under the best conditions, allylic amines were obtained in a 40-70% isolated yield. A complex derived from the stoichiometric reaction of Co(acacen), 1, with PhINTs has been isolated and spectroscopically characterized. Such a complex, although not able to transfer its NTs moiety to alkenes, is still active in catalyzing allylic amination of cyclohexene. © 2005 Elsevier B.V. All rights reserved.
9.
Gallo, E.; Caselli, A.; Ragaini, F.; Fantauzzi, S.; Masciocchi, N.; Sironi, A.; Cenini, S.
Structural determination of ruthenium-porphyrin complexes relevant to catalytic epoxidation of olefins Journal Article
In: Inorganic Chemistry, vol. 44, no. 6, pp. 2039-2049, 2005, ISSN: 00201669.
@article{Gallo20052039,
title = {Structural determination of ruthenium-porphyrin complexes relevant to catalytic epoxidation of olefins},
author = {E. Gallo and A. Caselli and F. Ragaini and S. Fantauzzi and N. Masciocchi and A. Sironi and S. Cenini},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-15944397219&doi=10.1021%2fic048587w&partnerID=40&md5=f71dcc185e16ef3f000934ef6d3dab5d},
doi = {10.1021/ic048587w},
issn = {00201669},
year = {2005},
date = {2005-01-01},
journal = {Inorganic Chemistry},
volume = {44},
number = {6},
pages = {2039-2049},
abstract = {A reproducible synthesis of a competent epoxidation catalyst, [Ru VI(TPP)(O)2] (TPP = tetraphenylporphyrin dianion), starting from [RuII(TPP)(CO)L] (L = none or CH3OH), is described. The molecular structure of the complex was determined by using ab initio X-ray powder diffraction (XRPD) methods, and its solution behavior was in detail investigated by NMR techniques such as PGSE (pulsed field gradient spin-echo) measurements. [RuIV(TPP)-(OH)]2O, a reported byproduct in the synthesis of [RuVI(TPP)(O)2], was synthesized in a pure form by oxidation of [RuII(TPP)(CO)L] or by a coproportionation reaction of [RuVI(TPP)(O)2] and [Ru II(TPP)(CO)L], and its molecular structure was then determined by XRPD analysis. [RuVI(TPP)(O)2] can be reduced by dimethyl sulfoxide or by carbon monoxide to yield [RuII(TPP)(S-DMSO) 2] or [RuII(TPP)(CO)(H2O)], respectively. These two species were characterized by conventional single-crystal X-ray diffraction analysis. © 2005 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A reproducible synthesis of a competent epoxidation catalyst, [Ru VI(TPP)(O)2] (TPP = tetraphenylporphyrin dianion), starting from [RuII(TPP)(CO)L] (L = none or CH3OH), is described. The molecular structure of the complex was determined by using ab initio X-ray powder diffraction (XRPD) methods, and its solution behavior was in detail investigated by NMR techniques such as PGSE (pulsed field gradient spin-echo) measurements. [RuIV(TPP)-(OH)]2O, a reported byproduct in the synthesis of [RuVI(TPP)(O)2], was synthesized in a pure form by oxidation of [RuII(TPP)(CO)L] or by a coproportionation reaction of [RuVI(TPP)(O)2] and [Ru II(TPP)(CO)L], and its molecular structure was then determined by XRPD analysis. [RuVI(TPP)(O)2] can be reduced by dimethyl sulfoxide or by carbon monoxide to yield [RuII(TPP)(S-DMSO) 2] or [RuII(TPP)(CO)(H2O)], respectively. These two species were characterized by conventional single-crystal X-ray diffraction analysis. © 2005 American Chemical Society.
2004
8.
Gasperini, M.; Ragaini, F.; Gazzola, E.; Caselli, A.; Macchi, P.
In: Dalton Transactions, no. 20, pp. 3376-3382, 2004, ISSN: 14779226.
@article{Gasperini20043376,
title = {Synthesis of mixed Ar,Ar′-BIAN ligands (Ar,Ar′-BIAN = bis(aryl) acenaphthenequinonediimine). Measurement of the coordination strength of hemilabile ligands with respect to their symmetric counterparts},
author = {M. Gasperini and F. Ragaini and E. Gazzola and A. Caselli and P. Macchi},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-9244234440&doi=10.1039%2fb406582d&partnerID=40&md5=04995bca47fcb82c997aa73e414078ff},
doi = {10.1039/b406582d},
issn = {14779226},
year = {2004},
date = {2004-01-01},
journal = {Dalton Transactions},
number = {20},
pages = {3376-3382},
abstract = {The synthesis of Ar,Ar′-BIAN ligands (Ar,Ar′-BIAN = bis(aryl)acenaphthenequinonediimine) having different aryl groups bound to the two nitrogen atoms is reported for the first time. The ligands were obtained by two different strategies: (i) by a transimination reaction starting from a symmetric Ar,Ar-BIAN ligand having aryl groups bearing strongly electron-withdrawing substituents or (ii) by a two-step-one-pot sequence. The ligands synthesized have been chosen so that the electronic difference between the two aryl groups is very large, but the steric difference is variable and, in one case, the ligand is almost sterically symmetric. The coordination strength of the new ligands towards three palladium complexes has been measured by a competition experiment following a protocol previously described by us. The coordination strength of the mixed ligands is the mean of those of the corresponding symmetric counterparts. The X-ray crystal structure of a palladium π-allyl complex of the electronically asymmetric-sterically symmetric ligand (3,5-(CF3)2C6H3),(3,5-Me 2C6H3)-BIAN has been solved, together with those of the two symmetric analogues to allow a comparison. Despite the fact that the dodecafluorinated ligand has a Keq value about three orders of magnitude lower than the non-fluorinated counterpart, no notable difference is observed in the N-Pd and Pd-Callyl distances in the three complexes. Calculations at the density functional level confirm that Pd-BIAN distances are not strictly correlated to the coordination energies, which are in qualitative agreement with the spectroscopic evidence. The bond length is thus not a good indication of the bond strength in these cases.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The synthesis of Ar,Ar′-BIAN ligands (Ar,Ar′-BIAN = bis(aryl)acenaphthenequinonediimine) having different aryl groups bound to the two nitrogen atoms is reported for the first time. The ligands were obtained by two different strategies: (i) by a transimination reaction starting from a symmetric Ar,Ar-BIAN ligand having aryl groups bearing strongly electron-withdrawing substituents or (ii) by a two-step-one-pot sequence. The ligands synthesized have been chosen so that the electronic difference between the two aryl groups is very large, but the steric difference is variable and, in one case, the ligand is almost sterically symmetric. The coordination strength of the new ligands towards three palladium complexes has been measured by a competition experiment following a protocol previously described by us. The coordination strength of the mixed ligands is the mean of those of the corresponding symmetric counterparts. The X-ray crystal structure of a palladium π-allyl complex of the electronically asymmetric-sterically symmetric ligand (3,5-(CF3)2C6H3),(3,5-Me 2C6H3)-BIAN has been solved, together with those of the two symmetric analogues to allow a comparison. Despite the fact that the dodecafluorinated ligand has a Keq value about three orders of magnitude lower than the non-fluorinated counterpart, no notable difference is observed in the N-Pd and Pd-Callyl distances in the three complexes. Calculations at the density functional level confirm that Pd-BIAN distances are not strictly correlated to the coordination energies, which are in qualitative agreement with the spectroscopic evidence. The bond length is thus not a good indication of the bond strength in these cases.
7.
Ragaini, F.; Cenini, S.; Turra, F.; Caselli, A.
In: Tetrahedron, vol. 60, no. 23, pp. 4989-4994, 2004, ISSN: 00404020.
@article{Ragaini20044989,
title = {Allylic amination of unfunctionalyzed olefins by nitroarenes and CO, catalyzed by Ru3(CO)12/Ph-BIAN (Ph-BIAN=bis(phenylimino) acenaphthenequinone): Extension to the synthesis of allylic amines with strongly electron-withdrawing or electron-donating groups on the aryl ring},
author = {F. Ragaini and S. Cenini and F. Turra and A. Caselli},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2442434684&doi=10.1016%2fj.tet.2004.04.034&partnerID=40&md5=9779cf40876f0a9fedfa5980c082ed1f},
doi = {10.1016/j.tet.2004.04.034},
issn = {00404020},
year = {2004},
date = {2004-01-01},
journal = {Tetrahedron},
volume = {60},
number = {23},
pages = {4989-4994},
abstract = {The allylic amination of unfunctionalyzed olefins by nitroarenes under CO pressure, catalyzed by Ru3(CO)12/Ph-BIAN (Ph-BIAN=bis(phenylimino)acenaphthenequinone) has been extended to some substrates with strongly electron-withdrawing groups on the nitroarene. Reaction of 1,4-dinitrobenzene selectively affords functionalization of only one nitro group, the other remaining unreacted. However, the second nitro group can be reduced in one pot by CO/H2O in the presence of the same catalytic system employed in the amination reaction, to afford the corresponding 4-amino derivative. Some attempts to render the reaction enantioselective by employing chiral bis-oxazolines as ligands in place of Ph-BIAN are described. Bis-oxazolines are suitable ligands for the reaction, although not as efficient as Ph-BIAN, but the allylic amine obtained was found to be racemic. © 2004 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The allylic amination of unfunctionalyzed olefins by nitroarenes under CO pressure, catalyzed by Ru3(CO)12/Ph-BIAN (Ph-BIAN=bis(phenylimino)acenaphthenequinone) has been extended to some substrates with strongly electron-withdrawing groups on the nitroarene. Reaction of 1,4-dinitrobenzene selectively affords functionalization of only one nitro group, the other remaining unreacted. However, the second nitro group can be reduced in one pot by CO/H2O in the presence of the same catalytic system employed in the amination reaction, to afford the corresponding 4-amino derivative. Some attempts to render the reaction enantioselective by employing chiral bis-oxazolines as ligands in place of Ph-BIAN are described. Bis-oxazolines are suitable ligands for the reaction, although not as efficient as Ph-BIAN, but the allylic amine obtained was found to be racemic. © 2004 Elsevier Ltd. All rights reserved.
2003
6.
Caselli, A.; Giovenzana, G. B.; Palmisano, G.; Sisti, M.; Pilati, T.
Synthesis of C2-symmetrical diamine based on (1R)-(+)-camphor and application to oxidative aryl coupling of naphthols Journal Article
In: Tetrahedron Asymmetry, vol. 14, no. 11, pp. 1451-1454, 2003, ISSN: 09574166.
@article{Caselli20031451,
title = {Synthesis of C2-symmetrical diamine based on (1R)-(+)-camphor and application to oxidative aryl coupling of naphthols},
author = {A. Caselli and G. B. Giovenzana and G. Palmisano and M. Sisti and T. Pilati},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0038060691&doi=10.1016%2fS0957-4166%2803%2900221-0&partnerID=40&md5=54c675f7ed410a92343e34f1502a144b},
doi = {10.1016/S0957-4166(03)00221-0},
issn = {09574166},
year = {2003},
date = {2003-01-01},
journal = {Tetrahedron Asymmetry},
volume = {14},
number = {11},
pages = {1451-1454},
publisher = {Elsevier Ltd},
abstract = {The new C2-symmetrical 1,2-diamine N,N′-bis[(1R,2R,4R)-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl]-1,2- ethanediamine3 has been synthesized from commercial (1R)-(+)-camphor 1 and scrutinized as ligand in the oxidative biaryl coupling of naphthol derivatives. Under the optimal conditions employing a Cu(I)-3 triflate complex (10 mol%) in dichloroethane-MeCN and molecular sieves with air as the oxidant, aryl coupling of naphthol derivatives could be achieved in satisfactory yields (48-90% yield) and ees of up to 65%. The ester moiety at the 3-position of the substrate was found to be crucial for a satisfactory asymmetric induction in the present coupling reaction. © 2003 Elsevier Science Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The new C2-symmetrical 1,2-diamine N,N′-bis[(1R,2R,4R)-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl]-1,2- ethanediamine3 has been synthesized from commercial (1R)-(+)-camphor 1 and scrutinized as ligand in the oxidative biaryl coupling of naphthol derivatives. Under the optimal conditions employing a Cu(I)-3 triflate complex (10 mol%) in dichloroethane-MeCN and molecular sieves with air as the oxidant, aryl coupling of naphthol derivatives could be achieved in satisfactory yields (48-90% yield) and ees of up to 65%. The ester moiety at the 3-position of the substrate was found to be crucial for a satisfactory asymmetric induction in the present coupling reaction. © 2003 Elsevier Science Ltd. All rights reserved.
2002
5.
Orsini, F.; Caselli, A.
In: Tetrahedron Letters, vol. 43, no. 40, pp. 7259-7261, 2002, ISSN: 00404039.
@article{Orsini20027259,
title = {SmI2-mediated reactions of diethyl iodomethylphosphonate with esters and lactones: A highly stereoselective synthesis of a precursor of the C-glycosyl analogue of thymidine 5′-(β-L-rhamnosyl)diphosphate},
author = {F. Orsini and A. Caselli},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037201151&doi=10.1016%2fS0040-4039%2802%2901540-X&partnerID=40&md5=6deb182547e72e8488e996aa21cc0572},
doi = {10.1016/S0040-4039(02)01540-X},
issn = {00404039},
year = {2002},
date = {2002-01-01},
journal = {Tetrahedron Letters},
volume = {43},
number = {40},
pages = {7259-7261},
abstract = {In the presence of samarium iodide diethyl iodomethylphosphonate reacts with esters to afford β-ketophosphonates. The protocol has been applied to sugar lactones to afford in fairly good yields intermediates that are useful precursors for a variety of potentially bioactive compounds, such as the C-glycosyl analogue of thymidine 5′-(β-L-rhamnosyl)diphosphate. © 2002 Elsevier Science Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In the presence of samarium iodide diethyl iodomethylphosphonate reacts with esters to afford β-ketophosphonates. The protocol has been applied to sugar lactones to afford in fairly good yields intermediates that are useful precursors for a variety of potentially bioactive compounds, such as the C-glycosyl analogue of thymidine 5′-(β-L-rhamnosyl)diphosphate. © 2002 Elsevier Science Ltd. All rights reserved.
4.
Orsini, F.; Caselli, A.
A new entry to β-hydroxyphosphonates: The SmI2-mediated reaction of diethyl iodomethylphosphonate with carbonyl compounds Journal Article
In: Tetrahedron Letters, vol. 43, no. 40, pp. 7255-7257, 2002, ISSN: 00404039.
@article{Orsini20027255,
title = {A new entry to β-hydroxyphosphonates: The SmI2-mediated reaction of diethyl iodomethylphosphonate with carbonyl compounds},
author = {F. Orsini and A. Caselli},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037201124&doi=10.1016%2fS0040-4039%2802%2901539-3&partnerID=40&md5=54537d83ee57a265fd967d5a57e08bb8},
doi = {10.1016/S0040-4039(02)01539-3},
issn = {00404039},
year = {2002},
date = {2002-01-01},
journal = {Tetrahedron Letters},
volume = {43},
number = {40},
pages = {7255-7257},
abstract = {In the presence of samarium iodide α-halophosphonates react with aliphatic carbonyl compounds (aldehydes and ketones) to afford β-hydroxyphosphonates in fairly good yields under neutral and mild conditions. Lower yields are obtained with aromatic carbonyl compounds. © 2002 Elsevier Science Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In the presence of samarium iodide α-halophosphonates react with aliphatic carbonyl compounds (aldehydes and ketones) to afford β-hydroxyphosphonates in fairly good yields under neutral and mild conditions. Lower yields are obtained with aromatic carbonyl compounds. © 2002 Elsevier Science Ltd. All rights reserved.
2000
3.
Caselli, A.; Solari, E.; Scopelliti, R.; Floriani, C.; Re, N.; Rizzoli, C.; Chiesi-Villa, A.
In: Journal of the American Chemical Society, vol. 122, no. 15, pp. 3652-3670, 2000, ISSN: 00027863.
@article{Caselli20003652,
title = {Dinitrogen rearranging over a metal-oxo surface and cleaving to nitride: From the end-on to the side-on bonding mode, to the stepwise cleavage of the N≡N bonds assisted by Nb(III)-calix[4]arene},
author = {A. Caselli and E. Solari and R. Scopelliti and C. Floriani and N. Re and C. Rizzoli and A. Chiesi-Villa},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034685509&doi=10.1021%2fja9943288&partnerID=40&md5=c5d95b38adedf8374ad7f88f441456dc},
doi = {10.1021/ja9943288},
issn = {00027863},
year = {2000},
date = {2000-01-01},
journal = {Journal of the American Chemical Society},
volume = {122},
number = {15},
pages = {3652-3670},
abstract = {Four-electron reduction of dinitrogen has been achieved in the reaction of N2 with [p-Bu(t)-calix[4]-(O)42Nb2(μ-M)2] (M = Li, 3; M = Na, 4; M = K, 5), which contain a very reactive Nb=Nb unit [Nb= Nb = 2.659(1) Å; 4], in THF. The reaction leads to the dinuclear complexes [p-But-calix[4]- (O)42(Nb≡ N-N≡Nb)]2- M+2 (M = Li, 6; M = Na, 7; M = K, g) [Nb≡N = 1.747(12) Å},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Four-electron reduction of dinitrogen has been achieved in the reaction of N2 with [p-Bu(t)-calix[4]-(O)42Nb2(μ-M)2] (M = Li, 3; M = Na, 4; M = K, 5), which contain a very reactive Nb=Nb unit [Nb= Nb = 2.659(1) Å; 4], in THF. The reaction leads to the dinuclear complexes [p-But-calix[4]- (O)42(Nb≡ N-N≡Nb)]2- M+2 (M = Li, 6; M = Na, 7; M = K, g) [Nb≡N = 1.747(12) Å
2.
Caselli, A.; Solari, E.; Scopelliti, R.; Floriani, C.
In: Journal of the American Chemical Society, vol. 122, no. 3, pp. 538-539, 2000, ISSN: 00027863.
@article{Caselli2000538,
title = {The stepwise four- and six-electron reduction of carbon monoxide to oxyalkylidyne, to carbide and oxide, then to carbide over an Nb-Oxo surface modeled by calix[4]arene1},
author = {A. Caselli and E. Solari and R. Scopelliti and C. Floriani},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034716336&doi=10.1021%2fja993251k&partnerID=40&md5=ac36722fe5d0c3b8403a562a1e9e9d80},
doi = {10.1021/ja993251k},
issn = {00027863},
year = {2000},
date = {2000-01-01},
journal = {Journal of the American Chemical Society},
volume = {122},
number = {3},
pages = {538-539},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
1999
1.
Caselli, A.; Solari, E.; Scopelliti, R.; Floriani, C.
In: Journal of the American Chemical Society, vol. 121, no. 36, pp. 8296-8305, 1999, ISSN: 00027863.
@article{Caselli19998296,
title = {A synthetic methodology to niobium alkylidenes: Reactivity of a Nb=Nb double bond anchored to a calix[4]arene oxo surface with ketones, aldehydes, imines, and isocyanides},
author = {A. Caselli and E. Solari and R. Scopelliti and C. Floriani},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033568347&doi=10.1021%2fja990647n&partnerID=40&md5=b77c3d4893d2a73a8145742201ed6ad0},
doi = {10.1021/ja990647n},
issn = {00027863},
year = {1999},
date = {1999-01-01},
journal = {Journal of the American Chemical Society},
volume = {121},
number = {36},
pages = {8296-8305},
abstract = {The active compound leading to the synthesis of niobium alkylidenes and niobium alkylidynes from ketones and aldehydes is a [Nb(III)=Nb(III)] dimer, [p-Bu(t)-calix[4]-(O)42Nb2Na2] (3), supported by the [p- Bu(t)calix[4]-(O)4] tetraanion. It was obtained from a stepwise reduction of [p-Bu(t)-calix[4]-(O)42Nb2(Cl)2] (1) through the intermediate formation of a [NbNb] dimer, [μ-p-Bu(t)-calix[4]-(O)42Nb2] (2). Complex 3 reacted with ketones and aldehydes, RR'CO, via the metathesis of the Nb=Nb bond with the carbonyl functionality, forming an equimolar amount of the niobium alkylidene [p-But-calix[4]-(O)4Nb=CRR')]Na [R = R' = Ph, 4; R = Ph, R' = Me, 5; R = Cp2Fe, R' = Me, 6; R = Ph, R' = CH2Ph, 7; RR' = (CH2)4, 8; R = Pr(n), R' = H, 10; R = Ph, R' = H, 11] and of the oxoniobium(V) complex [p-Bu(t)-calix[4]-(O)4Nb=ONa] (9). The easy separation of 9 from the niobium alkylidenes makes the reaction of 3 with ketones a useful synthetic methodology to obtain metal alkylidene derivatives. The niobium alkylidene 11 underwent a reversible protonation and deprotonation reaction, leading to the corresponding benzyl derivative [p- Bu(t)-calix[4]-(O)4Nb-CH2Ph)] (12) and to the bridging alkylidyne [p- Bu(t)-calix[4]-(O)42Nb2(μ-PhC)2Na4] (13). A proton transfer from 12 to 13, assisted by a basic solvent such as pyridine, led to 11. The latter compound has been obtained as a magnesium salt from a direct alkylation of 1 using 2 equiv of [Mg(CH2Ph)2]. The significant difference in the reaction rate of 3 with aldehydes or ketones, and the reaction of the niobium alkylidenes with an excess of aldehydes or ketones, leading to the coupling between the alkylidene and the carbonyl functionality, allowed us to carry out the McMurry synthesis of nonsymmetric olefins in a stepwise manner. The four-electron reduction of RNC by complex 3 led to the formation of a dimetalla-imino-alkylidyne, [p-Bu(t)-calix[4]-(O)4Nb(μ-RNC)-Nbμ-p- Bu(t)-calix[4]-(O)4Na2] [R = Bu(t), 14; R = 2,6-Me2C6H3, 15], while the reaction with the imine PhCH=NPh led to the η2-imino complex [p- Bu(t)-calix[4]-(O)4Nb(η2-PhCH-NPh)Na] (16). Both reactions shed some light on the niobium alkylidene formation from ketones and aldehydes. An X- ray structural analysis is given for one of each class of compounds, namely 6, 9, 11, 13, 15, and 16.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The active compound leading to the synthesis of niobium alkylidenes and niobium alkylidynes from ketones and aldehydes is a [Nb(III)=Nb(III)] dimer, [p-Bu(t)-calix[4]-(O)42Nb2Na2] (3), supported by the [p- Bu(t)calix[4]-(O)4] tetraanion. It was obtained from a stepwise reduction of [p-Bu(t)-calix[4]-(O)42Nb2(Cl)2] (1) through the intermediate formation of a [NbNb] dimer, [μ-p-Bu(t)-calix[4]-(O)42Nb2] (2). Complex 3 reacted with ketones and aldehydes, RR'CO, via the metathesis of the Nb=Nb bond with the carbonyl functionality, forming an equimolar amount of the niobium alkylidene [p-But-calix[4]-(O)4Nb=CRR')]Na [R = R' = Ph, 4; R = Ph, R' = Me, 5; R = Cp2Fe, R' = Me, 6; R = Ph, R' = CH2Ph, 7; RR' = (CH2)4, 8; R = Pr(n), R' = H, 10; R = Ph, R' = H, 11] and of the oxoniobium(V) complex [p-Bu(t)-calix[4]-(O)4Nb=ONa] (9). The easy separation of 9 from the niobium alkylidenes makes the reaction of 3 with ketones a useful synthetic methodology to obtain metal alkylidene derivatives. The niobium alkylidene 11 underwent a reversible protonation and deprotonation reaction, leading to the corresponding benzyl derivative [p- Bu(t)-calix[4]-(O)4Nb-CH2Ph)] (12) and to the bridging alkylidyne [p- Bu(t)-calix[4]-(O)42Nb2(μ-PhC)2Na4] (13). A proton transfer from 12 to 13, assisted by a basic solvent such as pyridine, led to 11. The latter compound has been obtained as a magnesium salt from a direct alkylation of 1 using 2 equiv of [Mg(CH2Ph)2]. The significant difference in the reaction rate of 3 with aldehydes or ketones, and the reaction of the niobium alkylidenes with an excess of aldehydes or ketones, leading to the coupling between the alkylidene and the carbonyl functionality, allowed us to carry out the McMurry synthesis of nonsymmetric olefins in a stepwise manner. The four-electron reduction of RNC by complex 3 led to the formation of a dimetalla-imino-alkylidyne, [p-Bu(t)-calix[4]-(O)4Nb(μ-RNC)-Nbμ-p- Bu(t)-calix[4]-(O)4Na2] [R = Bu(t), 14; R = 2,6-Me2C6H3, 15], while the reaction with the imine PhCH=NPh led to the η2-imino complex [p- Bu(t)-calix[4]-(O)4Nb(η2-PhCH-NPh)Na] (16). Both reactions shed some light on the niobium alkylidene formation from ketones and aldehydes. An X- ray structural analysis is given for one of each class of compounds, namely 6, 9, 11, 13, 15, and 16.