Nucleophilic trifluoromethylation of carbonyl compounds and disulfides with trifluoromethane and silicon-containing bases

Provided that DMF (or another N,N-dialkylformamide) is present in the react ion medium, at least in a catalytic amount, fluoroform trifluoromethylates efficiently carbonyl compounds, even enolizable ones, when opposed to (TMS) (2)N- M+, generated in situ from N(TMS)(3) and M+ F- or RO- Na+ When F- is used ina catalytic amount, silylated alpha-(trifluoromethyl)carbinols are-o btained: in this case, the four-component system HCF3/N(TMS)(3)/catalytic F -/catalytic DMF behaves like the Ruppert's reagent, especially as far as no nenolizable carbonyl compounds are concerned (CF3SiMe3 remains more efficie nt for enolizable carbonyl compounds). This process involves an adduct betw een DMF and -CF3 which is the true trifluoromethylating agent. In the same way, fluoroform efficiently trifluoromethylates disulfides and diselenides when deprotonated with a strong base selected from t-BuOK or N(SiMe3)(3)/Me 4NF (or TBAT). t-BuOK is more adapted to the trifluoromethylation of aryl d isulfides whereas N(SiMe3)(3)/F- is well suited to that of aliphatic disulf ides.