クマリン誘導体の合成研究 (第13報)

Abstract

Nitration of ethyl 8-hydroxycoumarin-3-carboxylate (I) in glacial acetic acid solution affords ethyl 5-nitro-8-hydroxycoumari-3-carboxylate (III), m.p. 203.5-204°, and ethyl 7-nitro-8-hydroxycoumarin-3-carboxylate (IV), m.p. 201-202°. Methylation of (III) and (IV) with methyl iodide respectively gives 8-methoxy compounds, (VII) of m.p. 184-186°, and (VIII) of m.p. 152°, respectively. On the other hand, nitration of 3-methoxy-salicylaldehyde acetate (XVI) affords 4-nitro (IX), m.p. 92-93°, 5-nitro (X), m.p. 142°, and 6-nitro (XI), m.p. 104°, compounds. By condensation of (IX) and (XI) with ethyl malonate, in the presence of piperidine, the position of the nitro group in the foregoing (III) and (IV) was determined.Hydrolysis of (I), (III), and (IV) with hydrochloric acid respectively afforded 8-hydroxycoumarin-3-carboxylic acid, m.p. 292-293° (decomp.), 5-nitro-8-hydroxycoumarin-3-carboxylic acid, m.p. 292-293° (decomp.), 5-nitro-8-hydroxycoumarin-3-carboxylic acid (V), 257-258°, and 7-nitro-8-hydroxycoumarin-3-carboxylic acid (VI), m.p. 246-248°.