Design and synthesis of new chiral pyridine–phosphite ligands for the copper-catalyzed enantioselective conjugate addition of diethylzinc to acyclic enones
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 CuBr2 as a precursor, the enantioselective additions to various substituted acyclic enones afforded products in high yields and good enantioselectivities ( ...