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Cyclopropanation of Olefins with Diazoalkanes, Catalyzed by Co II (porphyrin) Complexes − A Synthetic and Mechanistic Investigation and the Molecular Structure of Co III (TPP)(CH 2 CO 2 Et) (TPP = Dianion of meso ‐Tetraphenylporphyrin)
Author(s) -
Pei Andrea,
Wanke Riccardo,
Tollari Stefano,
Gallo Emma,
Musella Danilo,
Ragaini Fabio,
Demartin Francesco,
Cenini Sergio
Publication year - 2003
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200390189
Subject(s) - chemistry , cyclopropanation , porphyrin , cobalt , cyclopropane , olefin fiber , ethyl diazoacetate , catalysis , medicinal chemistry , tetraphenylporphyrin , selectivity , alkyl , organic chemistry , ring (chemistry)
Cobalt( II ) porphyrin complexes catalyze reactions between ethyl diazoacetate (EDA) and styrenes to give the corresponding cyclopropanes with trans selectivity. The reactions of other diazoalkanes and other olefins have also been carried out, and the mechanism of the reaction has been investigated. Kinetic data and stoichiometric reactions support the formation of a diazoalkane cobalt‐porphyrin complex that reacts with the olefins to generate the cyclopropane. Diethyl maleate and fumarate are not formed in the presence of an excess of olefin . On treatment of EDA with Co II (TPP) (TPP = dianion of meso ‐tetraphenylporphyrin) in the absence of the olefin, an alkyl cobalt( III ) complex Co III (TPP)(CH 2 CO 2 Et) was isolated, and its structure has been solved by X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)