A straightforward synthesis of benzothiazines.

A series of 4H-3,1-benzothiazines have been successfully synthesized through a three-step sequence starting from commercially available 2-iodoaniline. The key step consists of the cyclization of compounds 6 via an intramolecular S-conjugate addition. The synthesis is straightforward, gives good yields and offers a broad range of possibilities since R can be many alkyl or aryl groups and Z a suitable electron-withdrawing functionalization.