Calcium(ii)-catalyzed enantioselective conjugate additions of amines

Abstract

The direct enantioselective chiral calcium(II)·phosphate complex (Ca[CPA]₂)-catalyzed conjugate addition of unprotected alkyl amines to maleimides was developed. This mild catalytic system represents a significant advance towards the general convergent asymmetric amination of α,β-unsaturated electrophiles, providing medicinally relevant chiral aminosuccinimide products in high yields and enantioselectivities. Furthermore, the catalyst can be reused directly from a previously chromatographed reaction and still maintain both high yield and selectivity.