C([C:3]1[CH:4]=[C:5]([CH:15]=[CH:16][C:17]=1[B:18]1[O:22]C(C)(C)[C:20]([CH3:26])(C)[O:19]1)[O:6][C:7]1[CH:14]=[CH:13][C:10]([C:11]#[N:12])=[CH:9][N:8]=1)=O.C[Mg+].[Br-].Cl.C([O-])(O)=O.[Na+]>C1COCC1.O>[OH:22][B:18]1[C:17]2[CH:3]=[CH:4][C:5]([O:6][C:7]3[CH:14]=[CH:13][C:10]([C:11]#[N:12])=[CH:9][N:8]=3)=[CH:15][C:16]=2[CH:20]([CH3:26])[O:19]1To a suspension of 6-[3-formyl-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenoxy]-nicotinonitrile (105 mg, 0.3 mmol, 1.0 eq.) in THF (5.0 mL) at 0° C. was added MeMgBr (0.15 mL, 0.45 mmol, 1.5 eq.) drop wise. The mixture was stirred at 0° C. for 20 minutes and allowed to warm to room temperature in another 1 h. After cooling to 0° C., the clear solution was carefully treated with H2O (1 mL), followed by slow addition of HCl (10 mL, 3N). The resulting yellow suspension was allowed to ward to room temperature gradually and stirred for 2 h. The mixture was then treated with sat. NaHCO3 drop wise until PH reaching 1 and was extracted with EtOAc (3×10 mL). Combined organic extracts was washed with brine (10 mL), dried over MgSO4, filtered and the filtrate was concentrated under reduced pressure. The residue was applied to silica chromatography eluting with MeOH/DCM (0:100 to 10:90) to give 6-(1-hydroxy-3-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-5-yloxy)-nicotinonitrile as a white solid. LCMS (m/z) 267 (M+H); 1H NMR (DMSO-d6) δ: 9.19 (s, 1H), 8.71 (dd, J=2.3, 0.6 Hz, 1H), 8.38 (dd, J=8.7, 2.4 Hz, 1H), 7.80 (d, J=7.9 Hz, 1H), 7.28-7.35 (m, 2H), 7.20 (dd, J=7.9, 2.0 Hz, 1H), 5.26 (q, J=6.5 Hz, 1H), 1.45 (d, J=6.6 Hz, 3H).
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