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

A metal-free polychloromethyl radical-initiated cyclization of unactivated alkenes was developed using CHCl and CHCl as the di- and trichloromethyl radical sources. Variously substituted -allyl-indoles were successfully transformed into the corresponding C2-(di- and trichloromethyl) pyrrolo[1,2-]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 CHBr under standard conditions.