Control of site selectivity in trifluoromethylation of alkenes bearing a pendant indolyl group: Synthesis of CF3-containing tetrahydrocarbazoles

Abstract We present a tetrahydrocarbozole-forming carbo-trifluoromethylation of indoles bearing an alkenyl group at the C3 position. The reaction proceeded selectively with the combination of TsOH·H 2 O as a catalyst and CH 2 Cl 2 as a solvent. The site-selectivity could be altered by changing the reaction solvent; the use of THF instead of CH 2 Cl 2 increased the formation of aromatic trifluoromethylation products.