Synthesis of 6- and 7-acyl-4H-benzothiazin-3-ones

Synthesis of 6- and 7-substituted benzoxazin-3-ones was already described in the literature by acylation of the corresponding benzoxazin-3-ones or cyclization of the corresponding 4- or 5-acyl-2-aminophenols. This paper describes original synthetic pathways to afford the 6- and 7-acyl products in the benzothiazin-3-one series, respectively, via Stille coupling reaction and by acylation.