Copper(I)/SaBOX catalyzed highly diastereo- and enantio-selective cyclopropanation of cis -1,2-disubstituted olefins with α-nitrodiazoacetates

A copper-catalyzed highly stereoselective cyclopropanation of 1,2-disubstituted olefins with α-nitrodiazo acetates has been developed, giving the desired products in up to 97 % yields, up to >99/1 dr and up to 98 % ee, which provides an efficient access to the synthesis of optical active cyclopropane α-amino acids and unnatural α-amino acid derivatives.