Catalysis in water: synthesis of beta-amno amides by Sc(III) promoted condensation of silylketene pyridylthioacetal and imines

The scandium (III) catalysed condensation of silylketene thioacetals and pyridylthioacetals with imines in pure water was studied. The reaction of the phenylthioacetal derivatives brings always to b-aminoesters; the reaction of pyridylthioacetals leads to the stereoselective formation of b-lactams in organic solvents, while in the presence of a large amount of water affords b-amino amides in good yields. That represents a new, easy, one-pot catalytic synthesis in water of an interesting class of compounds, direct precursors of 1,3-diamino hydroxy compounds. The possibility of recovering and recycling the catalytic systems was also briefly investigated.