A new synthesis of indolo[2,3-b]quinolines from 3-acetyl-N-alkyl-2-chloroindoles with 2-aminobenzophenone.

A new synthesis of N-alkyl- and 11-phenyl-modified indolo[2,3-b]quinolines was achieved via PEG-400-promoted and visible light-induced one-step reaction of 3-acetyl-N-alkyl-2-chloroindoles with 2-aminobenzophenone in 40% methanol aqueous solution. The merits of the protocol include cost efficiency, convenience, and eco- and user-friendliness.