Organocatalytic Enantioselective Vinylogous Michael Reaction of Vinylketene Silyl-N,O-Acetals

The enantioselective vinylogous Michael reaction of vinylketene silyl N,O-acetals derived from alpha,beta-unsaturated N-acyl pyrroles and a broad range of alpha,beta-unsaturated aldehydes proceeds with good regio-, diastereo-, and enantioselectivity when the Hayashi-Jorgensen diphenylprolinolsilylether was employed as a chiral organocatalyst. Products were obtained in generally good yields and as single stereoisomers after chromatographic purification with very high optical purity. They were easily derivatized into a set of useful synthetic building blocks.