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温度

0 °C

A solution of (R)-2-methoxymethyl-2-methyl-but-3-enoic acid (600 mg, 4.2 mmol) in dichloromethane (40 mL) was stirred at 0° C. under nitrogen. Boron tribromide (1 M in dichloromethane, 16.8 mL, 16.8 mmol) was added and the reaction mixture was stirred at 0° C. for 90 minutes. Methanol (20 mL) was cautiously added and the reaction mixture was warmed to room temperature over 30 minutes and then stirred at room temperature for 30 minutes. The solvent was evaporated and the residue was purified by silica gel chromatography using a gradient of pentane/diethyl ether 3:1 to 1:1 to afford the title compound (540 mg, 90%) as a clear oil. 1H NMR (300 MHz, CDCl3) δ 1.35 (s, 3H), 2.33 (m, 1H), 3.62 (m, 1H), 3.75 (s, 3H), 3.75-3.80 (m, 1H), 5.21 (dd, J=17.4, 0.5 Hz, 1H), 5.24 (dd, J=10.7, 0.5 Hz, 1H), 5.98 (dd, J=17.4, 10.7 Hz, 1H). LCMS (m/z) 145.1 [M+H], Tr=1.16 min.

1. temperaturethe reaction mixture was warmed to room temperature over 30 minutes
2. stirringstirred at room temperature for 30 minutes
3. customThe solvent was evaporated
4. customthe residue was purified by silica gel chromatography