Simple synthesis of L- and D-vinylglycine (2-aminobut-3-enoic acid) and related amino acids

A three-step synthesis of vinylglycine 1 has been developed using a readily available starting material (but-3-enenitrile 2), based on the Neber rearrangement of the corresponding N-chloroimidate, and using cheap, convenient reagents. Also described is a convenient optical resolution of the N-tert-butoxycarbonyl derivative by papain-catalysed enantioselective esterification in a two-phase system. From the optically active amino acid, related amino acids obtained via epoxidation, dihydroxylation and cyclopropanation have been prepared. The related β, γ-unsaturated amino acids (E)-2-aminopent-3-enoic acid 20 and (E)-2-amino-3-methylpent-3-enoic acid 22 have been synthesised using the same approach.