Cyclopropanation of alkenes mediated by novel chiral Fischer carbenecomplexes

Abstract

The cyclopropanation reaction using chiral-at-metal Fischer carbene complexes is examined. Racemic molybdenum and chromium carbene complexes fac- and mer-1 and mer-2, respectively, undergo cycloaddition to acrylonitrile, methyl acrylate and 1-hexene to give cylopropanes 3 and 4 with trans/cis ratio up to 4.7:1. The cyclopropanation of acrylonitrile with the enantiopure carbene complex (+)-mer-1 resulted in a modest asymmetric induction of 2:1 for the trans-isomer 3a.