Pd-Catalyzed intramolecular C–H activation and C–S formation to synthesize pyrazolo[5,1-b]benzothiazoles without an additional oxidant

Abstract

Herein, an efficient synthesis of pyrazolo[5,1-b]benzothiazole scaffold via Pd-catalyzed intramolecular C–H activation and C–S formation was reported. By starting from easily available 1-phenyl-1H-pyrazole-5-thiol compounds, a series of substituted pyrazolo[5,1-b]benzothiazoles were obtained with moderate to good yields. Interestingly, this reaction didn't need any additional oxidant and the reaction conditions were also suitable for the synthesis of imidazo[2,1-b]benzothiazole derivatives.