Organocatalytic solvent-free hydrogen bonding-mediated asymmetric Michael additions under ball milling conditions

Abstract

An efficient, solvent-free protocol for asymmetric Michael additions of α-nitrocyclohexanone to nitroalkenes using thiourea derivatives as hydrogen bonding catalysts has been developed. By performing the organocatalytic reactions in a planetary ball mill, high yields (up to 97%) and excellent enantioselectivities (er up to 98 : 2) were achieved in short reaction times with low catalyst loadings.