Copper-Mediated Trifluoromethylation of α-Diazo Esters with TMSCF3: The Important Role of Water as a Promoter

Copper-mediated trifluoromethylation of alpha-diazo esters with TMSCF3 reagent has been developed as a new method to prepare alpha-trifluoromethyl esters. This trifluoromethylation reaction represents the first example of fluoroalkylation of a non-fluorinated carbene precursor. Water plays an important role in promoting the reaction by activating the CuCF3 species prepared from Cull TMSCF3/CsF (1.0:1.1:1.1). The scope of this trifluoromethylation reaction is broad, and its efficiency is demonstrated in the synthesis of a variety of aryl-, benzyl-, and alkyl-substituted 3,3,3-trifluoropropanoates.