[F:1][C:2]1([F:11])[O:6][C:5]2[CH:7]=[CH:8][CH:9]=[CH:10][C:4]=2[O:3]1.[Li]C(CC)C.C[O:18]B(OC)OC.OO.[OH-].[Na+]>C1COCC1.C1CCCCC1>[F:11][C:2]1([F:1])[O:3][C:4]2[CH:10]=[CH:9][CH:8]=[C:7]([OH:18])[C:5]=2[O:6]12,2-Difluoro-1,3-benzodioxole (320 mg, 2.05 mmol) was dissolved in THF (2.5 mL) and cyclohexane (1.2 mL) and the resulting solution cooled down to −78° C. sec-BuLi 2M solution in cyclohexane (1.025 ml, 2.05 mmol) was added drop wise and the reaction mixture stirred for 2 hours at −78° C. Trimethylborate (230 mg, 2.25 mmol) was added and the mixture was allowed to warm slowly to room temperature. A 30% w/w aqueous solution of H2O2 (4.1 mmol) and NaOH (82 mg, 2.05 mmol) were added and the reaction mixture stirred for 18 hours at room temperature. The reaction was quenched with a 2N aqueous solution of HCl and diluted with ethyl acetate. Two phases were separated and the organic layer was washed twice with brine, dried over Na2SO4 and evaporated to dryness, affording the title compound (340 mg).
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