D. Cremin, A. F. Hegarty
1977
Citations
0
Influential Citations
9
Citations
Journal
Tetrahedron
Abstract
Abstract Hydrolysis of phenyl-N-acetylanthranilate 1 (Ar = Ph) to N-acetyl anthranilie acid 3 is base catalysed and occurs through the intermediacy of 2-methyl-3,1-benzoxazin-4-one 4. Above pH 6 the formation of 4 from 1 is faster than the base (or acid) catalysed ring opening of 4 to 3. Electron-withdrawing substituents in the ester moiety (e.g. 1, Ar = p-NO2C6H4) aid cyclization to 4 relative to direct hydroxide catalyzed hydrolysis (to 3). Concomitantly, neutral amide participation is observed so that cyclization of 1 (Ar = p-NO2, m-NO2, m-Cl, p-ClC6H4) occurs even in acidic solution; the Hammett ϱ values for neutral and base catalysed cyclizations are compared. Hydrolysis of methyl-N-acetylanthranilate 6 to 3 occurs slowly in base, possibly without the formation of the intermediate 4.