Indolization by phosphorus trichloride of functionalized ketone arylhydrazones: synthesis of pharmacological interesting indoles

Abstract

The synthesis of indoles starting from phosphorus trichloride and arylhydrazones either functionalized in the ketone entity or N-substituted is reported. The reaction, carried out at room temperature, allows several substituents on the ketone framework of the hydrazone (e.g. ether, alkoxycarbonyl, halogeno, dialkylamino, olefinic, and phosphonic). Under optimum conditions high product yields were obtained. Evidence for the proposed mechanism is also reported.