Synthesis of certain novel 4H-pyrano[3,2-h]quinoline derivatives

Abstract

Treatment of 8-hydroxyquinoline 1a and 8-hydroxy-2-methylquinoline 1b with α-cyano-pchloro/bromocinnamonitriles 2a,b provided 4H-pyrano[3,2-h] quinoline-3-carbonitrile derivatives 3a-d, while treatment of (E) 2-(4-chlorostyryl)-8-hydroxyquinoline 7 with α-cyano-pchloro/ bromocinnamonitriles 2a,b and ethyl α-cyano-p-chloro/bromocinnamates 2d,e provided 4H-pyrano[3,2-h]quinoline-3-carbonitrile derivatives 8a,b and ethyl 4H-pyrano[3,2-h]quinoline-3-carboxylate derivatives 9a,b respectively. Interaction of 8-hydroxyquinoline 1a and 8-hydroxy-2-methylquinoline 1b with α-cyano-p-fluorocinnamonitrile 2c afforded 2-[4-(piperidin-1-yl) benzylidene]malononitrile 5 via a nucleophilic aromatic substitution reaction. The reactivity of 2-hydroxyquinoline and its 2-substituted derivatives towards α-cyano-p-chloro/bromocinnamonitriles and ethyl α-cyano-p-chloro/ bromocinnamates are discussed in this work. Structures of these compounds were established on the basis of IR, 1H NMR, 13C NMR, 13C NMR-DEPT and MS data. © ARKAT-USA, Inc.