Enantioselective hydrogenation of [alpha]-aminomethylacrylates containing a free N--H group for the synthesis of [beta]-amino acid derivatives

We describe highly enantioselective synthesis of [beta]-amino acid derivatives (1a-c) using asymmetric hydrogenation of a-aminomethylacrylates (2a-c), which contain a free basic N-H group, as the key step. The [alpha]-aminomethylacrylates (2a-c) were prepared using the Baylis-Hillman reaction of an appropriate aldehyde with methyl acrylate followed by acetylation of the resulting allylic alcohols (4a-b) and [S.sub.N]2'-type amination of the allylic acetates (3a-b). asymmetric catalysis | Baylis-Hillman reaction