C([Li])CCC.[Cl:6][C:7]1[CH:12]=[CH:11][C:10]([O:13][CH2:14][CH3:15])=[CH:9][C:8]=1I.[B:17](OC(C)C)([O:22]C(C)C)[O:18]C(C)C>CCCCCC.C1COCC1.CCOC(C)=O.Cl>[Cl:6][C:7]1[CH:12]=[CH:11][C:10]([O:13][CH2:14][CH3:15])=[CH:9][C:8]=1[B:17]([OH:22])[OH:18]
Add, dropwise, 5.5 mL (8.8 mmol) of a 1.6N solution of butyllithium in hexane in the space of 30 min to a solution of 2.38 g (8.4 mmol) of 1-chloro-2-iodo-4-ethoxybenzene in 50 mL of anhydrous THF cooled under argon to −78° C. After 2 h at −70° C., add 1.74 g (9.2 mmol) of triisopropyl borate and stir the reaction mixture for 3 h at room temperature, then distribute in 200 mL of EtOAc/HCl aq 5N 1:1 mixture. Wash the organic phase with 50 mL of water, dry over Na2SO4 and concentrate under reduced pressure. Purify the residue obtained by silica gel column chromatography, eluting with a DCM/methanol gradient from 0 to 10% of methanol. After concentration under reduced pressure, we obtain 990 mg of (2-chloro-5-ethoxyphenyl)boronic acid, in the form of oil.
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