Collect. Czech. Chem. Commun. 1998, 63, 520-524

Cyclization of Phenacyl 2-{[2,2-Di(ethoxycarbonyl)vinyl]amino}benzoate

Pavel Hradila, Lubomír Kvapila, Jan Hlaváčb, Karel Lemrc and Juraj Ševčíkc

a Farmak, a. s., 771 17 Olomouc, Czech Republic
b Department of Organic Chemistry, Palacký University, 771 46 Olomouc, Czech Republic
c Department of Analytical Chemistry, Palacký University, 771 46 Olomouc, Czech Republic


Reaction of phenacyl anthranilate (1) with diethyl (ethoxymethylidene)malonate afforded phenacyl 2-{[2,2-di(ethoxycarbonyl)vinyl]amino}benzoate (2) which on heating in polyphosphoric acid underwent degradation. Thermal cyclization of 2 in diphenyl ether gave phenacyl 3-(ethoxycarbonyl)-4-oxo-1,4-dihydroquinoline-8-carboxylate (4). The phenacyl group did not cyclize even on prolonged heating at 250 °C. Heating in sulfuric acid resulted in hydrolysis of the ethyl ester under formation of 4-oxo-8-[(phenacyloxy)carbonyl]-1,4-dihydroquinoline-3-carboxylic acid (6). The structure of 4 was confirmed by an independent synthesis.

Keywords: Thermal cyclization; Phenacyl aminobenzoate; Quinolones; Gould-Jacobs reaction.