Catalytic asymmetric direct-type 1,4-addition reactions of simple esters

Abstract

In the presence of catalytic amounts of potassium hexamethyldisilazide (KHMDS) and a chiral macrocyclic crown ether, asymmetric 1,4-addition reactions of simple esters with α,β-unsaturated amides proceeded to afford the desired 1,4-adducts in high yields with good stereoselectivities. Mechanistic investigations revealed that proper combination of substrates was a key for the efficient catalytic turnover.