Access to Highly Substituted 7‑Azaindoles from 2‑Fluoropyridines via 7‑Azaindoline Intermediates

Abstract

A versatile synthesis of 7-azaindoles from substituted 2-fluoropyridines is described. C3-metalation and 1,4-addition to nitroolefins provide substituted 2-fluoro-3-(2-nitroethyl)­pyridines. A facile oxidative Nef reaction/reductive amination/intramolecular S_NAr sequence furnishes 7-azaindolines. Finally, optional regioselective electrophilic C5-substitution (e.g., bromination or nitration) and subsequent in situ oxidation delivers highly functionalized 7-azaindoles in high overall efficiency