Asymmetric Organocatalytic Synthesis of Substituted Chiral 1,4-Dihydropyridine Derivatives. Fernando Auria-Luna, Eugenia Marqués-López, M. Concepción Gimeno, Roghayeh Heiran, Somayeh Mohammadi, and Raquel P. Herrera, J. Org. Chem. 2017, 82, 5516–5523.
Abstract. The first cinchona-alkaloid-organocatalyzed enantioselective synthesis of chiral 1,4-dihydropyridine derivatives is described. Bis-cinchona catalyst 3b activates the Michael addition reaction between malononitrile derivatives 2 and enamines 1, affording the appealing and highly substituted 1,4-dihydropyridines 4 with very good results in most cases. This is one of very few examples of the synthesis of chiral 1,4-dihydropyridines by an enantioselective catalytic procedure. The highly substituted final compounds are of interest for their potential biological activity. This efficient protocol opens the door to a new area of research for the asymmetric construction of these skeletons for which enantioselective syntheses are still very limited.