Design and synthesis of new chiral pyridine–phosphite ligands for the copper-catalyzed enantioselective conjugate addition of diethylzinc to acyclic enones

Abstract

A series of new chiral pyridine–phosphite ligands have been prepared from ( R)-pyridyl alcohols and BINOL-derived chlorophosphite, and successfully employed in the copper-catalyzed enantioselective conjugate addition of diethylzinc to acyclic enones. Using the simple and inexpensive CuBr 2 as a precursor, the enantioselective additions to various substituted acyclic enones afforded products in high yields and good enantioselectivities (up to 92% ee).