Studies on annelated 1,4-benzothiazines and 1,5-benzothiazepines. I. Synthesis of 4H-s-triazolo[3,4-c]-1,4-benzothiazine and derivatives with potential CNS activity.

As a part of a program toward the synthesis and the pharmacological studies on annelated 1,4-benzothiazines and 1,5-benzothiazepines, a number of 4H-s-triazolo[3,4-c]-1,4-benzothiazine derivatives were prepared and tested for their CNS activity. The syntheses of the new tricyclic compounds (VII) were performed via the 2H-1,4-benzothiazine-3(4H)-thiones (II) which were obtained by Lawesson's thiation of lactams (I). Compounds (II) and their S-methyl-thioethers (III), quantitatively obtained by PTC method, were reacted with acylhydrazines to give the title compounds. Some triazolobenzothiazines (VII) were also prepared from 3-hydrazinoderivatives (IV) by cyclization with either an aliphatic acid or the corresponding orthoesther.