Synthesis of chiral urethane N-alkoxycarbonyl tetramic acids from urethane N-carboxyanhydrides (UNCAs)

The synthesis of chiral N-protected tetramic acid derivatives which are important precursors of beta-hydroxy gamma-amino acid under mild conditions is described. Reaction of urethane-N-carboxyanhydrides (UNCAs) with Meldrum's acid in the presence of a tertiary amine, followed by subsequent cyclisation produced tetramic acid derivatives. This procedure is applicable to Boc-, Fmoc- and Z- N-carboxyanhydrides.