Preparation of potentially bioactive aza and thiaza polycyclic compounds containing a bridgehead nitrogen atom. Synthesis of pyrrolo[1,2,3-de]-1,4-benzothiazine derivatives

The synthesis of some pyrrolo1,2,3-de]-1,4-benzothiazine derivatives by using a modified Bischler type cyclization of N-(2,2-diethoxyethyl)-2H-1,4-benzothiazines as a crucial step is described. The alternative approach based on Friedel-Crafts alkylation of the N-(2-chloroethyl)-2H-1,4-benzothiazines is shown to be impractical due to the low yield obtained.