Efficient synthesis of new a-b-unsaturated alkyl-ester peptide-linked chiral amines

Four new a-b-unsaturated alkyl-ester chiral amines were synthesized in excellent yields (84–95%) via peptide couplings from their corresponding a-b-unsaturated alkyl-ester anilines and N-Boc protected chiral aminoacids. To our delight, these polyfunctionalized compounds are being used as starting reagents in Ugi-type three-component reactions (Ugi-3CR), together with alkyl- and aryl-aldehydes, and a couple of chain-ring tautomerizable aminoacid-containing isocyanides to synthesize novel oxazole-based macrocycle precursors. Thus, the aim of this communication is to show our most recent results of the synthesis and use of new and complex chiral amines to assemble macrocyclic polypeptides with potential application in medicinal chemistry, such as the post-surgical antibiotic Vancomycin.