Four-component 1,4-addition Ugi reaction catalyzed by the Schiff base derived from Tröger's base and BINOL

Abstract

The 1,4-addition Ugi reaction can provide complex, novel and bioactive structures. However, Ugi reaction involving the 1,4-addition process has rarely been reported due to the Michael addition of amine to α,β-unsaturated ketones or aldehydes prevents the formation of the key intermediate iminium ion. In this paper, a Schiff base catalyst derived from Tröger's base-NH2 and (R)-BINOL-CHO was used successfully to promote the four-component 1,4-addition Ugi reaction of α,β-unsaturated cyclic ketones, carboxylic acids, aromatic amines and isocyanides to afford an α,β-keto amide 2-arylformyl-3-(arylamino)cyclopent-2-enecarboxamides in high yield (6, 83–96%) under mild condition. A variety of aromatic amines participated in the reaction efficiently, which showed the high efficiency of the catalyst. A reasonable catalysis and formation mechanism were come up with.