Enantioselective Access to Five- and Six-membered Nitrogen-containing Heterocycles, Based on the Asymmetric Michael Addition of Chiral Imines and Chiral Enamino Esters

Abstract

The addition reaction of chiral imines, (ent-lO,48,70) and chiral enamino esters (52, 55, 73) with maleic anhydride (32), citraconic anhydride (57).a-chloroacrylonitrile (29).and nitroethylene (74), has been investigated.These condensations proved to be in general highly regio-, diastereo-, and enantioselective.In most cases the primary adducts underwent an in situ Nheterocyclization, allowing the enantioselective access to nitrogen-containing, fiveand six-membered heterocycles.