Lewis acid-catalyzed tandem synthesis of 9-sulfonylamino- and 9-arylfluorenes

Abstract

A Lewis acid-catalyzed three-step tandem synthesis of 9-arylfluorene was developed by simply heating a mixture of 2-formyl biphenyl, TsNCO and an arene. In the absence of arene, a two-step tandem synthesis of 9-sulfonylaminofluorene was achieved. These advances were mainly attributed to the discovery of an anhydrous synthesis of N-tosyl arylaldimines from TsNCO and arylaldehydes.