[CH3:1][C:2]1[CH:7]=[CH:6][C:5]([B:8]([OH:10])[OH:9])=[CH:4][CH:3]=1.O.[Br:12]Br>CC(Cl)(Cl)Cl.N(C(C)(C)C#N)=NC(C)(C)C#N>[Br:12][CH2:1][C:2]1[CH:7]=[CH:6][C:5]([B:8]([OH:10])[OH:9])=[CH:4][CH:3]=1A mixture of 4-methylphenylboronic acid (27.2 g; 0.2 mole) in methyl chloroform (250 ml) was heated at reflux with azeotropic removal of water until approximately 2.5 ml of water was collected and a crystalline slurry was formed. A solution of azo(bisisobutyronitrile) (1.0 g) and bromine (32 g) in methyl chloroform (25 ml) was added to the refluxing slurry over 2-3 hours. The mixture was then refluxed until the bromine colour was discharged. The reaction mixture was allowed to cool and stirred at 10°-15° C. for 30 minutes. The suspended solid was collected by filtration, washed with methyl chloroform (2×50 ml) and dried at ambient temperature to give the anhydride of 4-bromomethylphenylboronic acid (29 g) (Compound F) as a white, crystalline solid, which was used without further purification or characterisation.
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