SYNTHESIS AND REACTIONS OF NOVELPYRAZOLO[1,5-c][1,3]THIAZINE-7-THIONES

Abstract

The reaction of 1,5-diaryl-4-pentyne-1,3-diones with S-ammonium hydrazinecarbodithiolate led to the formation of a new ring system, the pyrazolo[1,5-][1,3]thiazines, which were converted into the corresponding pyrazoles. These pyrazolothiazines gave with hydrazine hydrate the respective pyrazolo[1,5-b]pyrazoles. with hydrogen peroxide in glacial acetic acid, pyrazolo[4,3-c]thiopyran-4-ones were formed. The latter reactions furnish a new semies of pyrazolo[1,5-b]pyrazoles and a new heterocyclic system, pyrazolo[4,3-c]thiopyrans.

Key Words:

• Acetylenic β-diketones
• pyrazolothiazinethiones
• pyrazolopyrazoles and pyrazolothiopyran 4-ones
• synthesis and structure elucidation