Synthesis of α-Sulfonyl Ketones via I2/TBHP Promoted Radical Sulfonylation of Silyl Enol Ethers with Sulfohydrazides under Mild Conditions

A I-2/TBHP mediated reaction of readily prepared silyl enol ethers with sulfonylhydrazides was developed for the synthesis of alpha-sulfonyl ketones under mild conditions. Twenty-two alpha-sulfonyl ketone derivatives were obtained in 22%-72% yields under the optimized reaction conditions. Their structures were confirmed by nuclear magnetic resonance spectroscopy (NMR). Moreover, the present catalytic protocol exhibited good functional group tolerance and substrate applicability, and various substituents such as halogen, nitro, trifluoromethyl, furan and naphthalene can be successfully converted to corresponding alpha-sulfonyl ketones. The preliminary mechanistic studies disclose that the reaction may proceed via a radical pathway.