Enantioselective Lewis acid catalyzed Michael reactions of alkylidene malonates.: Catalysis by C2-symmetric bis(oxazoline) copper(II) complexes in the synthesis of chiral, differentiated glutarate esters

Ct-symmetric bis(oxazorine)-Cu(TT) complexes 1 catalyze the Mukaiyama Michael reaction of alkylidene malonates and enolsilanes The use of hexafluoro-2-propanol is essential to induce catalyst turnover. High enantioselectivities are exhibited by bulky alkylidene malonate beta-substituents using catalyst la. The glutarate ester products are readily decarboxylated to provide chiral 1,5-dicarbonyl synthons. Crystallographic characterization of substrate-catalyst complexes provides insight into the binding event with these catalysts and affords a rationale for the observed facial selectivities.