Cyclization of free radicals at the C-7 position of ethyl indole-2-carboxylate derivatives: an entry to a new class of duocarmycin analogues

Aryl free-radicals generated at the C-7 position of ethyl indole-2-carboxylates bearing N-allyl and propargylic groups triggered intramolecular cyclizations to furnish a new class of Duocarmycin analogues, formal ethyl pyrrolo[3,2,1-ij]quinoline-2carboxylate derivatives, through the less favorable 6-endo-trig cyclization mode.