Copper(II) triflate-catalyzed and tosyl isocyanate-mediated three-step tandem synthesis of 9-arylfluorenes

Abstract A Cu(OTf) 2 -catalyzed and TsNCO-mediated three-step tandem synthesis of 9-arylfluorenes were developed from biphenyls and aryl aldehydes, by which the electron-poor 9-aryl substituted fluorenes were synthesized smoothly. Its success is mainly attributed to use an anhydrous synthesis of N -tosyl arylaldimines as a key step, which was achieved in situ from the reaction of TsNCO and aryl aldehydes.