Trifluoromethyl 1-radical-mediated carbonylation of alkanes leading to ethynyl ketones

The carbonylation of alkanes 1 under radical-reaction conditions was examined by using ethynyl triflone A as the unimolecular chain-transfer (UMCT) reagent. Good to moderate yields of ethynyl ketones 2 were prepared by means of this three-component coupling reaction. Higher CO pressures as well as lower concentrations of triflone A improved the efficiency of the reaction over the direct addition, the latter leading to alkylated ethynes 3. In contrast to the reaction with A, the reaction of cyclohexane (1a) with allyl triflone B (= ethyl 2-methylene-3-[(trifluoromethyl)sulfonyl]propanoate) in the presence of CO gave a mixture of carbonylation products, including 8a formed from two molecules each of cyclohexane, CO, and allyl triflone B.