[Cl:1][C:2]1[C:10]2[CH:9]([CH2:11][C:12]([O:14]CC)=[O:13])[O:8][B:7]([OH:17])[C:6]=2[CH:5]=[C:4]([O:18]C(C)C)[CH:3]=1.[Li+].[OH-].Cl>C1COCC1.O>[Cl:1][C:2]1[C:10]2[CH:9]([CH2:11][C:12]([OH:14])=[O:13])[O:8][B:7]([OH:17])[C:6]=2[CH:5]=[C:4]([OH:18])[CH:3]=1To a solution of ethyl 2-(4-chloro-1-hydroxy-6-isopropoxy-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate (200 mg, 0.74 mmol) in 10 mL THF was added LiOH (100 mg, 2.22 mmol) in 5 mL H2O dropwise at 0° C. The mixture was stirred at room temperature for 1.5 h and acidified to pH=5.0 using 1N HCl (8 mL). The resulting mixture was extracted with EtOAc (3×10 mL). The combined organic layers were dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was use directly in next step reaction without further purification.
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