A novel highly C3 selective metal free trifluoroethylation of indoles using 2,2,2-trifuoroethyl(mesityl)-iodonium triflate was developed. The methodology enables the introduction of a trifluoroethyl group in a fast and efficient reaction under mild conditions with high functional group tolerance. Beyond the synthetic developments, quantum chemical calculations provide a deeper understanding of the transformation.

Efficient Direct 2,2,2-Trifluoroethylation of Indoles via C-H Functionalization. -If 3-methylindole is used as starting material, formation of any trifluoroethylated product is not observed. -(TOLNAI, G. L.; SZEKELY, A.; MAKO, Z.; GATI, T.; DARU, J.; BIHARI, T.; STIRLING*, A.; NOVAK, Z.; Chem. Commun. (Cambridge) 51 (2015) 21, 4488-4491, http://dx.doi.org/10.1039/C5CC00519A ; Res. Cent. Nat. Sci., Hung. Acad. Sci., H-1117 Budapest, Hung.; Eng.) -G. Mueller 29-155