Trifluoromethylthiolation and Trifluoromethylselenolation of [alpha]-Diazo Esters Catalyzed by Copper

[alpha]-Diazo esters are smoothly converted into the corresponding trifluoromethyl thio- or selenoethers by reaction with Me4NSCF3 or Me4NSeCF3, respectively, in the presence of catalytic amounts of copper thiocyanate. This straightforward method gives high yields under neutral conditions at room temperature and is applicable to a wide range of functionalized molecules, including diverse [alpha]-amino acid derivatives. It is well-suited for the late-stage introduction of trifluoromethylthio or -seleno groups into drug-like molecules.