Iron‐Catalyzed Gamma‐Gamma Dimerization of Siloxydienes

Abstract

AbstractWe report the oxidative dimerization reaction of siloxydienes derived from simple enones that creates a new gamma‐gamma (γ‐γ) C−C bond using catalytic iron and benzoyl peroxide as the terminal oxidant in acetonitrile solvent at ambient temperature. The reaction shows a broad substrate scope including cyclic and acyclic siloxydienes derived from ketones, aldehydes, and esters, which are converted to 1,8‐dicarbonyl compounds under mild catalytic reaction conditions in 19–89 % yield across 30 examples. The method is suitable for the coupling of sterically demanding carbon centers, including the formation of vicinal quaternary centers. Conceptually, the dienol ether serves as a precursor to a conjugated radical cation, which undergoes highly site selective γ‐dimerization reactions. The γ‐γ dimerization strategy is applied to the synthesis of a bioactive analogue of honokiol.