[Synthesis]
Method 1,
 Under ice bath conditions, triisopropyl orthoformate (5.71 g, 30 mmol) was slowly added to trifluoromethanesulfonic anhydride (5.0 ml, 30 mmol). The reaction was monitored by NMR for 15 minutes. After the reaction was complete, the mixture was distilled under reduced pressure to obtain 4.32 g of colorless liquid trifluoromethanesulfonic acid, yield 75%.
TfO(i-Pr):bp25℃(1mmHg);1H NMR(400MHz, CDCl3)δ5.25-5.19(m,1H),1.52(d, J＝6.3Hz,7H);13C NMR (101MHz, CDCl3)δ118.5(q,J＝320.5Hz),86.4,23.0; 19F NMR (376MHz, CDCl3)δ-75.9(s,3F). Method 2.
 (1) Dissolve 16.8 g (0.1 mol) of trifluoromethanesulfonyl chloride in 40 ml of pyridine solvent, and slowly add 6.0 g (0.1 mol) of isopropanol at room temperature. After the addition is complete, stir for 3 hours to allow the reaction to proceed; (2) Recover the solvent under reduced pressure, dissolve the resulting residue in 30 ml of ethyl acetate to obtain an ester layer, wash the ester layer with water, dry the ester layer with anhydrous sodium sulfate, remove ethyl acetate under reduced pressure, and obtain 18.4 g of crude isopropyl trifluoromethanesulfonate, with a yield of 95.8%. |