N-Primary-amine tetrapeptide-catalyzed highly asymmetric Michael addition of aliphatic aldehydes to maleimides

The highly asymmetric Michael addition reaction between maleimides and aliphatic aldehydes catalyzed by low-loading beta-turn tetrapeptides with excellent yields and enantioselectivities at room temperature was reported. alpha-Branched and alpha-unbranched aldehydes both are suitable nucleophiles.N-Aryl, alkyl and hydrogen maleimides all are well tolerated and led to high yields and enantioselectivities. The transformation can be enlarged to the gram scale without decrease in the yield and enantioselectivity. Furthermore, the succinimides were converted into gamma-lactams and gamma-lactones, showing good practicality of this work. Some reaction intermediates in the proposed reaction mechanism can be captured with the HR-MS method.