Remarkable enhancement of enantioselectivity in the asymmetric conjugate addition of dimethylzinc to (Z)-nitroalkenes with a catalytic [(MeCN)₄Cu]PF₆-Hoveyda ligand complex

Abstract

An enantioselective copper-catalyzed asymmetric conjugate addition of Me2Zn to (Z)-nitroalkenes led to the formation of all-carbon quaternary stereogenic centers with high stereoselectivity. The key features of the new method are the unprecedented use of [(MeCN)4Cu]PF6 in conjunction with the Hoveyda ligand L1 and the use of (Z)-nitroalkene substrates so that undesired nitroalkene isomerization is minimized and enantioselectivity is enhanced dramatically. We also describe a novel, practical, and highly (Z)-selective nitroalkene synthesis.

Keywords: asymmetric conjugate addition; copper; nitroalkenes; quaternary stereocenters; zinc.