胺基N-O化合物引发
由于氟离子和金属烷氧化合物的强碱性，这些引发剂不适用于对碱敏感的底物，并且它们对湿气非常敏感。而三乙基胺N-O化合物可作为活化TMSCF3的亲核性的催化剂，该引发剂适用于对碱敏感的底物。多种芳香族，脂肪族以及α,β-不饱和醛在三乙基胺N-O化合物引发下都能以中等到良好的收率生成相应的三氟甲基化产物1。
示例：
General Procedure for the Addition of TMSCF3 to Aldehyde/Ketone under Me3N+-O-in DMF.
Aldehyde/ketone(1 mmol) and TMSCF3 (neat) in dry DMF (3 mL) were placed in a 25 mL round-bottom flask (or a 30 mL vial). To this solution was added Me3N+-O-(0.05 eq.), and the mixture was stirred vigorously at room temperature. Completion of the reaction was monitored by TLC and GCMS. The reaction mixture was then poured in brine solution (15 mL) and extracted with diethyl ether (3×30 mL). Combined organic layers were finally washed with brine solution, dried over anhydrous Na2SO4, and then solvent was removed under reduced pressure. The crude product was further purified by chromatography to afford pure TMS-protected alcohols.
醋酸盐引发
醋酸锂通过活化Me3SiCF3的C-Si键催化三氟甲基化反应。多种醛，酮以及酰亚胺化合物在催化量醋酸锂的存在下与Ruppert-{attr}2101{/attr}作用以高收率生成相应的三氟甲基化的产物。另外，使用苯甲酸锂，三甲基乙酸锂以及醋酸钠，醋酸钾，醋酸铵都能有效的高产率的得到三氟甲基化产物。该方法非常实用，因为它仅需要温和并且价廉易得的路易斯碱催化剂2。
示例：
Typical Experimental Procedure for Trifluoromethylation of Carbonyl Compounds.
To a stirred solution of AcOLi(1.3mg, 0.02mmol) in DMF(0.6mL) were added successively a solution of aldehyde (0.4 mmol) in DMF(0.6 mL) and TMSCF3 (74.8μL, 0.48mmol, 95% content) at 0 oC. The mixture was stirred for 10min at the same temperature, and then quenched with saturated aqueous NH4Cl. The mixture was extracted with Et2O and the organic layer was washed with brine and dried over anhydrous Na2SO4. After filtration and evaporation of the solvent, the crude product was purified by preparative TLC to afford the corresponding adduct(80%).
【参考文献】
1.Surya Prakash, G. K.; Mandal, M.; Panja, C.; Mathew, T.; Olah, G. A. J.Fluo. Chem. 2003, 123, 61-63.
2.Kawano, Y.; Kaneko, N.; Mukaiyama, T. Bull. Chem. Soc. Jpn. 2006,79, 1133-1145.
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