Hydrochloric Acid → 4-Fluoro-1-hydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborole-6-carbaldehyde

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Reaction Steps

To a solution of 4-fluoro-3,3,6-trimethylbenzo[c][1,2]oxaborol-1(3H)-ol (1.94 g, 10 mmol) in CCl4 (19.4 mL) at rt was added benzoyl peroxide (0.24 g, 1.0 mmol) and NBS (3.56 g, 20 mmol). The reaction mixture was refluxed for 16 h, cooled to rt and treated with Na2CO3. The aqueous layer was acidified with 3 N HCl to pH of 3 and extracted with EA. The organic layer was washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by column chromatography over silica gel eluted with PE-EA (2:1) to give 4-fluoro-1-hydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborole-6-carbaldehyde (1.86 g, 89.4% yield) as a brown solid. 1H NMR (400 MHz, DMSO-d6) δ 10.04 (d, J=1.6 Hz, 1H), 9.53 (s, 1H), 8.09 (s, 1H), 7.77 (m, 1H), 1.55 (d, J=5.6 Hz, 6H) ppm.

Provenance & Evidence