[F:1][C:2]1[C:3]([O:12][CH3:13])=[C:4]([C:8]([F:11])=[CH:9][CH:10]=1)[C:5]([OH:7])=[O:6].[Li+].CC([N-]C(C)C)C.C(NC(C)C)(C)C.[Li]CCCC.[B:34](OCC)([O:38]CC)[O:35]CC.OS(O)(=O)=O>C1COCC1>[B:34]([C:10]1[CH:9]=[C:8]([F:11])[C:4]([C:5]([OH:7])=[O:6])=[C:3]([O:12][CH3:13])[C:2]=1[F:1])([OH:38])[OH:35]To a solution of 3,6-difluoro-2-methoxybenzoic acid (i-6b) (0.94 g, 5 mmol) in THF (5 mL) at −70° C. was added a solution of LDA [freshly prepared from diisopropylamine (1.51 g, 15 mmol) and n-BuLi (10M solution in hexane, 1.5 mL, 15 mol) in THF (15 mL). The resultant solution was stirred for 15 mins, followed by the addition of B(OEt)3 (1.46 g, 10 mmol). The mixture was stirred for 15 mins and then hydrolyzed with dilute aq. H2SO4. The organic phase was separated and the aqueous layer was extracted with Et2O. The combined organics were concentrated and the residue solid was washed with H2O and hexane, dried to give the title compound as white crystals. LCMS (ESI) calc'd for C8H7BF2O5 [M+H]+: 233. found: 233.
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