Preparation of 2H‐spiro[benzo[d]isothiazole‐3,3′‐pyrazole]‐1, 1‐dioxide‐2′(4′H)‐carboxylates from dilithiated C(α),N‐carboalkoxyhydrazones and methyl 2‐(aminosulfonyl)benzoate

Abstract

A variety of substituted spiro(benzoisothiazole-pyrazoles) have been prepared by the condensation of dilithiated C(a),N-carboalkoxyhydrazones with lithiated methyl 2-(aminosulfonyl)benzoate followed by the cyclization of intermediates with acetic anhydride, which also resulted in spiro N-acetylated products when carbomethoxyhydrazones or carboethoxyhydrazones were used, and spiro NH products when carbo-tert-butoxyhydrazones were used.