Studies on 1,3-benzoxazines. III. Reaction of imidoyl chlorides of 1,3-benzoxazines with 2-hydroxy- or 2-mercaptopyridine N-oxides: A novel S-N bond formation via electrocyclic rearrangement.
Studies on 1,3-benzoxazines. III. Reaction of imidoyl chlorides of 1,3-benzoxazines with 2-hydroxy- or 2-mercaptopyridine N-oxides: A novel S-N bond formation via electrocyclic rearrangement.
A novel S-N bond formation through 3, 3-sigmatropic rearrangement in the reaction of imidoyl chlorides of 1, 3-benzoxazines (1) with 2-mercaptopyridine N-oxide (8) is described. Treatment of the imidoyl chlorides (1a-f) with 2-hydroxypyridine N-oxide (2) afforded the corresponding pyridone derivatives (3a-f). When 2-mercaptopyridine N-oxide (8) was used instead of 2, the thiopyridones (7) or N-oxides (9) were obtained and both compounds were transformed to 3-(2-pyridylthio)-4-oxo-2, 3-dihydro-1, 3-benzoxazines (13) through electrocyclic rearrangement on heating in a suitable solvent.