Novel preparation of 2,1-benzothiazine derivatives from sulfonamides with [hydroxy(tosyloxy)iodo]arenes

Cyclization of sulfonamides bearing an aromatic ring at the beta-position with various organohypervalent iodine compounds was carried out to form the corresponding 2,1-benzothiazine derivatives. Among them, the cyclization effectively proceeded with [hydroxy(tosyloxy)iodo]arenes through ionic pathways. The same treatment of a sulfonamide bearing a 4-methoxyphenyl group at the beta-position generated a spiro compound.