Novel synthesis of 2,2,2-trifluoroethyl compounds from homoallylic alcohols: a copper( I ) iodide-initiated trifluoromethyl–dehydroxylation process

Benzyl, prop-2-ynyl and ally chlorodifluoroacetates 3a, bromodifluoroacetates 3b or fluorosulfonyldifluoroacetates 3c, when decomposed in the presence of 1 equivalent of copper(I) iodide at an appropriate temperature in dimethylformamide, gave the corresponding trifluoromethyl derivatives in good to excellent yields. The products can also be obtained directly by ester exchange of XCF2CO2Et (X = FSO2, Cl, Br)6 and the corresponding alcohols in the presence of KF and Cul. A trifluoromethylation–dehydroxylation mechanism, initiated by Cul, is proposed.