Trifluoromethanesulfinamide from Ephedrine: A More Efficient Trifluoro-methylating Reagent
作者:Thierry Billard、Bernard R. Langlois、Solveig Roussel、Laurent Saint-Jalmes
DOI:10.1055/s-2004-831322
日期:——
Nucleophilic trifluoromethylation of non-enolizable and enolizable carbonyl compounds was achieved with the trifluoromethanesulfinamide derived from O-silylated ephedrine. In contrast to the trifluoroacetamide analog, previously described, this reagent is able to trifluoromethylate more acidic enolizable compounds.
Nucleophilic Trifluoromethylation of Carbonyl Compounds and Disulfides with Trifluoromethane and Silicon-Containing Bases
作者:Sylvie Large、Nicolas Roques、Bernard R. Langlois
DOI:10.1021/jo000150s
日期:2000.12.1
Provided that DMF (or another N,N-dialkylformamide) is present in the reaction 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-obtained: 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 nonenolizable carbonyl compounds are concerned (CF3SiMe3 remains more efficient for enolizable carbonyl compounds). This process involves an adduct between 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)/Me4NF (or TBAT). t-BuOK is more adapted to the trifluoromethylation of aryl disulfides whereas N(SiMe3)(3)/F- is well suited to that of aliphatic disulfides.
Neunhoeffer et al., Chemische Berichte, 1959, vol. 92, p. 252,255