Trifluoromethyl Group (CF3) Induced Regioselective Larock Indole Synthesis from Unsymmetric β-CF3-1,3-enynes

The indole skeleton exists widely in natural products, pharmaceuticals, and materials. We disclose here a trifluoromethyl group induced regioselective Larock indole synthetic method from unsymmetric 2-CF3-1,3-enynes. The presence of a trifluoromethyl group is determinable for the regioselectivity. Once the CF3 group was replaced with the methyl or phenyl group, a ratio of 1:1 to 1:1.4 isomers were obtained. This strategy features good regioselectivity, broad substrate scope, and high functional group tolerance. The protocol reported here offers an alternative solution to the rare 3,4-functionalization of 2-CF3-1,3-enynes. The products were further transformed to show distinctive reactivity in hydroboration-oxidation and hydro-bromination.