Synthetic uses of thio- and selenoesters of trifluoromethylated acids. 1. Preparation of trifluoromethyl sulfides and selenides

Trifluorothioacetates (CF3CO-S-R, from (CF3CO)(2)O and thiols) as well as trifluoromethanethio-or trifluoromethaneselenosulfonates (CF3SO2-Y-R; Y = S, Se; from CF3SO2Na, RYYR, and Br-2) can be formally decarbonylated or desulfonylated, respectively, provided that they are photolyzed at 40 degrees C in the presence of 1 equiv of the corresponding disulfide or diselenide. Trifluoromethyl sulfides or selenides are obtained, and the added disulfide (or diselenide) is recovered after reaction. In such a way, S-(trifluoromethyl)cysteine derivatives can be obtained.