N‐Heterocyclic Carbene Catalysis in Natural Product and Complex Target Synthesis

Synthesis of Highly Congested Tertiary Alcohols via the [3,3] Radical Deconstruction of Breslow Intermediates

“…Since the seminal reports by Breslow and co-workers on the formation of stabilized carbenes by deprotonation of thiazolium salts, N-heterocyclic carbenes (NHC) have become invaluable tools for the construction of carbon–carbon bonds in organic synthesis. , In a typical mechanism, the NHC reacts with an aldehyde derivative to form a nucleophilic enaminol species denoted “Breslow intermediate” capable of reaction with a wide range of electrophiles, eventually leading to a functionalized ketone after NHC regeneration. While two-electron pathways are often operative and have been widely studied, radical processes have recently emerged, opening a new realm of reactivities to explore with these versatile enaminol intermediates.…”