Synthesis of esters by selective methanolysis of the trifluoromethyl group

The trifluoromethyl group of certain compounds containing one or two trifluoromethyl groups can be converted to the carbomethoxy group by treatment with sodium methoxide followed by aqueous acidic work-up. α-Trifluoromethyl esters can be obtained by selective methanolysis of the 1,1,1,3,3,3-hexafluoroisopropyl group in some cases. The structural requirements for the transformation are delineated, and a mechanistic study confirms the proposed mechanism, a dehydrofluorination–addition–elimination process.