[CH3:1][O:2][C:3](=[O:12])[C:4]1[CH:9]=[CH:8][C:7]([CH2:10][OH:11])=[CH:6][CH:5]=1.B(F)(F)F.[CH3:17][CH2:18][O:19]CC.C(OCC)(=O)C>ClCCl>[CH3:1][O:2][C:3](=[O:12])[C:4]1[CH:9]=[CH:8][C:7]([CH2:10][O:11][CH2:17][CH2:18][OH:19])=[CH:6][CH:5]=1To a flame-dried 2-neck flask was added a solution of methyl-4-(hydroxymethyl)benzoate (2.5 g, 15 mmol) in dichloromethane (30 mL). The reaction was purged with nitrogen and brought to −5° C. A dewar condenser (also flame-dried) containing a dry ice/acetone bath (−78° C.) was affixed to the flask and ethylene oxide-tetradeuterate was added (˜55 drops). Then BF3.Et2O (510 μL, 0.0041 mmol) was added dropwise and the reaction stirred at −5° C. for 35 minutes under nitrogen atmosphere. Monitoring by TLC (100% ethyl acetate) showed complete consumption of the starting material. The reaction was warmed to room temperature and vented to remove any excess ethylene oxide gas. The reaction was then diluted with brine and extracted with dichloromethane (2 times). The combined organics were dried over Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil. Purification by flash column chromatography (4:1 pentane:ethyl acetate) provided the product as a clear oil (520 mg, 16% yield). 1H NMR (600 MHz, CDCl3) δ 8.02 (d, 2H, J=8.2 Hz), 7.41 (d, 2H, J=8.1 Hz), 4.62 (s, 2H), 3.92 (s, 3H); 13C NMR (150 MHz, CDCl3167.1, 143.5, 130.8,) δ 129.9, 127.5, 72.8, 52.4.
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