Catalytic enantioselective synthesis of indolizino[8,7-b]indole alkaloid derivatives based on the tandem reaction of tertiary enamides

Abstract

An exquisite catalytic asymmetric tandem reaction of tertiary enamides catalyzed by a chiral Diph-Pybox/Cu(OTf)₂ complex was developed. The method, which comprised an enantioselective intramolecular addition of tertiary enamides to ketonic carbonyls followed by the diastereoselective interception of acyliminium by a tethered indole moiety, enables the expeditious synthesis of indolizino[8,7-b]indole derivatives with high yields, and excellent enantioselectivity and diastereoselectivity.