Cinchonamine Squaramide Catalyzed Asymmetric aza‐Michael Reaction: Dihydroisoquinolines and Tetrahydropyridines

The first example of a chiral cinchona‐squaramide catalyzed enantioselective intramolecular aza‐Michael addition for the synthesis of dihydroisoquinolines and tetrahydropyridines has been developed. In general, good yields and excellent enantioselctivities were observed. Broad classes of Michael acceptors, such as enones, esters, thioesters, and Weinreb amides, were successful substrates. The possibility of recycling the catalysts has also been demonstrated. An oxidation of combined enamine and keto functionalities on chiral dihydroisoquinolines leads to a single diastereomer of an architecturally unprecedented tetracyclic core without loss in enantioselectivity.