Cobalt(II)-catalyzed asymmetric olefin cyclopropanation with α-ketodiazoacetates

Abstract

Porphyrin and Co.: The cobalt(II) complex 1 is an effective metalloradical catalyst for cyclopropanation of alkenes with α-acetodiazoacetates at room temperature to yield E-1,1-cyclopropaneketoesters in high yields with both high diastereo- and enantioselectivities. Epimerization of the resulting enantioenriched E-diastereoisomers into the corresponding Z-isomers with retention of the enantiopurity is promoted by iodide. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.