Michael addition of thiols, carbon nucleophiles and amines to dehydroamino acid and dehydropeptide derivatives

Michael additions of nitrogen heterocycles, thiols, carbon nucleophiles and amines to dehydroalanine derivatives, including a glycyldehydroalanine peptide, were performed in fair to good yields. Dehydroaminobutyric acid derivatives reacted only with the stronger nucleophiles but in considerably lower yields and often no reaction was observed with the corresponding dehydrophenylalanine derivatives. When a tosyl group was bonded to the nitrogen atom of the dehydroamino acid, in some cases the addition product underwent elimination of this group and yielded the corresponding b-substituted derivative of the a,b-dehydroamino acid. Addition of some b- dicarbonyl compounds led to formation of products to which the structure of a,a-disubstituted cyclic amino acid derivatives was assigned