Aza-ortho-Quinone Methides as Reactive Intermediates: Generation and Utility in Contemporary Asymmetric Synthesis

The aza- ortho -quinone methide (aza- o -QM) chemistry has overwhelmingly progressed in the past few decades. This review aims to integrate various transition metal-catalyzed and organocatalytic strategies in taming aza -o- QM intermediates, including its the aza- para -quinone methide (aza- p -QM), aza- ortho -vinylidene quinone methide (aza- o -VQM), aza- ortho -alkynyl quinone methide (aza- o -AQM), and indole-based aza- o -QM analogs. These transient species are often utilized for the direct and enantioselective synthesis of complex (hetero)polycyclic or fused-ring molecular scaffolds such as tetrahydroquinoline and indoline, among others, which are abundant in many natural products, bioactive compounds, and pharmaceuticals.