Metal-free sulfonyl radical-initiated cascade cyclization to access sulfonated indolo[1,2-a]quinolines.

A metal-free cascade reaction was developed for the synthesis of indolo[1,2-a]quinoline derivatives from arylsulfonyl hydrazides and 1-(2-(arylethynyl)phenyl)indoles in the presence of TBAI/TBHP. Impressively, these products exhibit excellent fluorescence properties, which is promising for cell imaging.