An asymmetric vinylogous Mukaiyama-Michael reaction of α,β-unsaturated 2-acyl imidazoles catalyzed by chiral Sc(III)- or Er( III)-pybox complexes

A highly diastereo- and enantioselective vinylogous Mukaiyama-Michael reaction of silyloxyfurans with alpha,beta-unsaturated 2-acyl imidazoles catalyzed by either chiral Sc(III) or Er(III) complexes of a pybox ligand has been reported. The enantioenriched gamma-butenolides formed in the reaction were further transformed into highly functionalized gamma-lactones found as important structural frameworks in a wide range of biologically active natural products.