Catalytic Synthesis of 1 <i>H</i> -2-Benzoxocins: Cobalt(III)-Carbene Radical Approach to 8-Membered Heterocyclic Enol Ethers
Minghui Zhou, Lukas A. Wolzak, Zirui Li, Felix J. de Zwart, Simon Mathew, Bas de Bruin
Abstract
-2-benzoxocins in high yields. The catalytic cyclization reactions proceed with excellent chemoselectivities, have a high functional group tolerance, and provide several opportunities for the synthesis of new bioactive compounds. The reactions are shown to proceed via cobalt(III)-carbene radical intermediates, which are involved in intramolecular hydrogen transfer (HAT) from the allylic position to the carbene radical, followed by a near-barrierless radical rebound step in the coordination sphere of cobalt. The proposed mechanism is supported by experimental observations, density functional theory (DFT) calculations, and spin trapping experiments.
Topics & Concepts
ChemistryCarbeneEnolCatalysisCobaltEnol etherOrganic chemistryMedicinal chemistryRadical Photochemical ReactionsCatalytic C–H Functionalization MethodsSulfur-Based Synthesis Techniques