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A mixture of 32.3 g (148 mmol) of 4,4,5,5-tetramethyl-2-(2-methylphenyl)-1,3,2-dioxaborolane, 25.0 g (141 mmol) of N-bromosuccinimide, and 0.32 g (2.62 mmol) of AIBN was refluxed in 1000 ml of acetonitrile for 2 h. The mixture was then cooled to room temperature and then evaporated to dryness. The residue was dissolved in 500 ml of hexane. The formed precipitate was filtered on glass frit (G3), and the filtrate was evaporated to dryness to give yellowish crystalline powder. Yield 28.9 g (66%). Anal. calc. for C13H18BBrO2: C, 52.57; H, 6.11. Found: C, 52.63; H, 6.29. 1H NMR (CDCl3): 7.81 (m, 1H, 6-H), 7.37-7.42 (m, 2H, 3, 5-H), 7.28 (m, 1H, 4-H), 4.91 (s, 2H, CH2Br), 1.37 (s, 1H, Bpin).

1. customevaporated to dryness
2. dissolutionThe residue was dissolved in 500 ml of hexane
3. filtrationThe formed precipitate was filtered on glass frit (G3)
4. customthe filtrate was evaporated to dryness
5. customto give yellowish crystalline powder