Tetrahedron

Sterically crowded cyclopropanation catalysts. Syn-selectivity using rhodium (III) porphyrins

HJ Callot, F Metz, C Piechocki

Index: Callot, H. J.; Metz, F.; Piechocki, C. Tetrahedron, 1982 , vol. 38, # 15 p. 2365 - 2369

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Citation Number: 109

Abstract

Rhodium (III) porphyrins catalyze the decomposition of ethyl diazoacetate and the transfer of ethoxy-carbonylcarbene to alkenes to form cyclopropanes in moderate to high yields. When compared with other catalysts a large syn-selectivity was observed on reaction with cis- alkenes. This selectivity increased with the size of the substituents, and suggested a preferential direction of approach of the alkene towards a rhodium—carbene complex.