Abstract Treatment of xanthates R-OC (S) SMe with (HF) 9/Py and 1, 3-dibromo-5, 5- dimethylhydantoin gives trifluoromethyl ethers R-OCF 3 through intermediates R-OCF 2 SMe, which could be isolated upon treatment of xanthates with n-Bu 4 N+ H 2 F 3− and N- bromosuccinimide.