Novel Synthesis of Quinoline Derivatives with Triethyl Phosphite

Abstract

Treatment of ethyl 4, 5-dimethoxy-2-nitrobenzylidenemalonate (III), ethyl 4-benzyloxy-5-methoxy-2-nitrobenzylidenemalonate (IV), and ethyl 4, 5-methylenedioxy-2-nitrobenzylidenemalonate (V) with triethyl phosphite at 160-170° for 20 hr afforded 2-ethoxy-3-ethoxycarbonyl-6, 7-dimethoxyquinoline (VI), 7-benzyloxy-2-ethoxy-3-ethoxycarbonyl-6-methoxyquinoline (VII), and 2-ethoxy-3-ethoxycarbonyl-6, 7-methylenedioxyquinoline (VIII), respectively, in 53-68% yield. On the other hand, the 6-benzyloxy-2-ethoxycarbonyl-5-methoxyindole (XIII) was obtained with the same treatment of ethyl 4-benzyloxy-3-methoxy-2-nitrocinnamate (XII).