Ammonium Chloride Promoted Ugi Four-Component,Five-Center Reaction of a-Substituted a-lsocyano Acetic Acid:A Strong Solvent Effect

摘要

Conditions have been developed for the multicomponent synthesis of di- and tetrapeptide(7)based on the unique reactivity of a-isocyano acetic acid(4 and its a -substituted derivatives)by an Ugi four-component,five-center reaction.Simply mixing 4,a carbonyl compound(aldehyde or ketone,8),and a secondary amine(9)(ratio:1:1:2)in toluene in the presence of 1.5 equiv of ammonium chloride afforded the desired product in good to excellent yield as a mixture of two diastereomers.