SYNTHESIS OF PERFLUOROALKYLATED INDENES

A series of perfluoroalkylated indenes has been synthesized using four different synthetic pathways. 1-(Pentafluoroethyl)indene and 2-(pentafluoroethyl)indene were prepared by the addition of (pentafluoroethyl)lithium to the appropriate ketones and subsequent dehydration. 2-(Trifluoromethyl)indene was synthesized through the photoinduced addition of trifluoromethyl iodide to indene, followed by dehydroiodination. 1-(Trifluoromethyl)indene was prepared by the addition of (trifluoromethyl)trimethylsilane to 1-indanone followed by deprotection and dehydration and by the sigmatropic cyclization of the appropriate phenylvinyl carbocation. This latter approach was also used to synthesize 1,3-bis(trifluoromethyl)indene and 1,2,3-tris(trifluoromethyl)indene.