Metal-free polychloromethyl radical-initiated cyclization of unactivated N -allylindoles towards pyrrolo[1,2- a ]indoles.

A metal-free polychloromethyl radical-initiated cyclization of unactivated alkenes was developed using CH 2 Cl 2 and CHCl 3 as the di- and trichloromethyl radical sources. Variously substituted N -allyl-indoles were successfully transformed into the corresponding C2-(di- and trichloromethyl) pyrrolo[1,2- a ]indoles in moderate to good yields. This reaction has a broad substrate scope and good functional group tolerance. Dibromomethylated products can also be obtained using CH 2 Br 2 under standard conditions.