C[O:2][C:3](=[O:13])[C@:4]([CH2:8][O:9][CH:10]([F:12])[F:11])([CH3:7])[CH:5]=[CH2:6].O.[OH-].[Li+].Cl>O1CCCC1.O>[F:11][CH:10]([F:12])[O:9][CH2:8][C@@:4]([CH3:7])([CH:5]=[CH2:6])[C:3]([OH:13])=[O:2]A solution of (R)-2-difluoromethoxymethyl-2-methyl-but-3-enoic acid methyl ester (159 mg, 0.8 mmol) in tetrahydrofuran (6 mL) was stirred at 5° C. under nitrogen. A solution of lithium hydroxide monohydrate (100 mg, 2.4 mmol) in water (1.5 mL) was added and the reaction mixture was stirred at 5° C. for 1 h and then at room temperature for 20 h. Water was added and the mixture was acidified to pH 2 with hydrochloric acid (2 M) and the mixture was extracted with diethyl ether. The organic extracts were combined and washed with brine. The organic solution was filtered through a hydrophobic frit and the filtrate was evaporated to afford the title compound (133 mg, 92%) as a clear oil. 1H NMR (300 MHz, d6-DMSO) 61.24 (s, 3H), 3.80 (d, J=9.4 Hz, 1H), 4.02 (d, J=9.4 Hz, 1H), 5.19 (dd, J=10.6 Hz, 1H), 5.20 (d, J=17.6 Hz, 1H), 5.91 (dd, J=17.6, 10.6 Hz, 1H), 6.68 (t, J=75.6 Hz, 1H), 12.5-13.0 (br s, 1H). LCMS (m/z) 179.1 [M−H], Tr=1.79 min.
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