A complementary method to obtain N-acyl enamides using the Heck reaction:: extending the substrate scope for asymmetric hydrogenation

A method to prepare N-acyl enamides is reported that is complementary to the existing protocols. Heck reaction of a variety of aryl trifluoromethanesulfonates with commercially available N-vinylacetamide occurred in a highly regioselective fashion to provide these valuable synthetic intermediates. This method permits the formation of N-acyl enamides containing functionality that would not be tolerated by the existing methods. Asymmetric hydrogenation using [diphosphine RhCOD]BF4 complexes provided optically active protected amines in up to 99% ee. De-acylation occurs without affecting the amine enantiopurity. (C) 2004 Elsevier Ltd. All rights reserved.