Syntheses of 3, 4-Dihydro-2H-1, 4-benzoxazine-2-acetates and Related Compounds

Abstract

The intramolecular Michael addition of 4-(2-hydroxyanilino)-2-butenoates (3), -2-buteno-nitrile, and their 3-phenyl analogs (8) gave 3, 4-dihydro-2H-1, 4-benzoxazine-2-acetates (4), -2-acetonitrile (6), and their 3-phenyl analogs (9), respectively, in good yields. In addition, 3, 4-dihydro-3-oxo-2H-1, 4-benzoxazine-2-acetates (13) and 3, 4-dihydro-2-(p-nitrobenzyl)-2H-1, 4-benzoxazine (16) were synthesized from 2-hydroxyanilines (1) by the addition reaction of fumaric acid chloride monoester (11) and p-nitrocinnamyl bromide (14), respectively. In order to examine the biological activities of the 2H-1, 4-benzoxazine analogs, 2-(2-dialkylaminoethyl)-(18) and 2-(2, 2-diphenylethyl)-2H-1, 4-benzoxazines (19, 20) were prepared.Among the compounds synthesized, 4b and 19a showed considerable anxiolytic activity in the conflict test in rats, while the oxalates of 18a-c showed potent anticonvulsant activity.