Homologation of the Fischer Indolization: A Quinoline Synthesis via Homo-Diaza-Cope Rearrangement

We disclose a new Bronsted acid promoted quinoline synthesis, proceeding via homo-diaza-Cope rearrangement ofN-aryl-N '-cyclopropyl hydrazines. Our strategy can be considered a homologation of Fischer's classical indole synthesis and delivers 6-membered N-heterocycles, including previously inaccessible pyridine derivatives. This approach can also be used as a pyridannulation methodology toward constructing polycyclic polyheteroaromatics. A computational analysis has been employed to probe plausible activation modes and to interrogate the role of the catalyst.