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

We disclose a new Brønsted acid promoted quinoline synthesis, proceeding via homo‐diaza‐Cope rearrangement of N‐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.