N‐Arylthiomethylaroylamides substituted with an electron‐donating group in the meta position undergo two‐directional cyclization in the presence of phosphorus oxychloride to give both positional isomers of the 4H‐1,3‐benzothiazine derivative. The structures of the products were confirmed by 1H and 13C nmr spectroscopy. Mixed ring‐closure reactions of several N‐arylthiomethylaroylamides 3, 6, 9, 13 have shown that these conversions are introduced by a proton‐catalyzed intermolecular rearrangement.
ASJC Scopus subject areas
- Organic Chemistry