CYCLIZATION OF PHENACYL 2-([2,2-DI(ETHOXYCARBONYL)VINYL]AMINO)BENZOATE

Reaction of phenacyl anthranilate (1) with diethyl (ethoxymethylidene) malonate afforded phenacyl 2-{[2,2-di(ethoxycarbonyl)vinyl]amino}benzo ate (2) which on heating in polyphosphoric acid underwent degradation. Thermal cyclization of 2 in diphenyl ether gave phenacyl carbonyl)-4- oxo-1,4-dihydroquinoline-8-carboxylate (ib). The phenacyl group did no t cyclize even on prolonged heating. at 250 degrees C. Heating in sulf uric acid resulted in hydrolysis of the ethyl ester under formation of cyloxy)carbonyl]-1,4-dihydroquinoline-3-carboxylic acid (6). The stru cture of 4 was confirmed by an independent synthesis.