Pyridine → Trifluoromethanesulfonic acid 2-[1-methyl-3-(trimethylsilyl)-2-propynyl]phenyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 20.9 grams (95.7 mmol, 1.0 eq) of phenol 6 in 92.0 mL of CH2Cl2 was stirred in a 250 mL round bottom flask under argon at room temperature. To this colorless solution was then added 580 mg (4.8 mmol, 0.05 eq) of N,N-dimethylaminopyridine followed by 46.0 mL (574 mmol, 6.0 eq) of pyridine. This solution was then cooled to 0° C. in an ice water bath. Once cooled, 19.3 mL (114.8 mmol, 1.2 eq) of Tf2O was carefully added to the cold solution. Once the addition of Tf2O was complete, the ice water bath was removed and the black solution was stirred at room temperature until complete by TLC (7:1 hexane:EtOAc, KMnO4 stain). Upon completion (˜30 minutes), the solution was diluted with Et2O and washed with 1.0 M HCl twice, followed by washings with water and brine. The organic fraction was then dried over MgSO4, concentrated and purified via vacuum distillation yielding 24.88 grams (74% for two steps) of a colorless oil, Rf 0.69 (7:1 hexane:EtOAc). 1H-NMR (500 MHz, CDCl3): 7.76 (dd, J=7.8 Hz, 1.7 Hz, 1H), 7.41 (dt, J=1.2 Hz, 7.6 Hz, 1H), 7.34 (dt, J=1.7 Hz, 7.8 Hz, 1H), 7.29 (dd, J=1.5 Hz, 8.5 Hz, 1H), 4.14 (q, J=7.1 Hz, 1H), 1.52 (d, J=7.1 Hz, 3H), 0.21 (s, 9H). 13C-NMR (500 MHz, CDCl3): 146.66, 135.94, 129.88, 128.92, 128.82, 121.33, 118.73 (q, J=320 Hz), 107.57, 87.12, 27.40, 23.56, 0.21. 19F-NMR (500 MHz, CDCl3): −74.37. IR (cm−1): 2960 (w), 2169 (w), 1757 (w), 1422 (s), 1214 (s), 1142 (s), 886 (s), 844 (s), 761 (m). HRMS (EI) calcd. for C14H17F3O3SSi: 350.0620. found: 350.0619.

Provenance & Evidence