Synthesis of novel β-substituted α,β-dehydroamino acid derivatives

β-Substituted α,β-dehydroamino acids are synthesised in high yields by a Michael addition of heterocyclic nucleophiles to the methyl esters of N-tert-butyloxycarbonyl,N-(4-toluenesulfonyl)dehydroamino acids, followed by a base-induced elimination of the 4-toluenesulfonyl group with regeneration of the α,β-double bond.