Pyrazolo[3,4-e] [1,4] thiazepines: Synthesis and structure proof

Pyrazolo3,4-e]1,4]thiazepine derivatives were obtained by reacting 5-amino-1,3-dimethylpyrazole with arylaldehydes or ketones and mercaptoacetic acid. The structure proof of these derivatives was carried out by identifying the benzylpyrazole products obtained by desulfurization and subsequent hydrolysis, and by comparison of the spectral data of a series of analogous pyrazolothiazepines. Treating the pyrazolothiazepines with sodium hydride and methyl iodide in dimethylformamide or dimethylsulfoxide resulted in a ring contraction with the elimination of sulfur, to yield the pyrazolopyridones in addition to the N-methylpyrazolothiazepines.