Triisopropyl borate → 6-Fluorobenzo[c][1,2]oxaborole-1,5(3H)-diol

Participants

Reaction Conditions

Reaction Steps

A solution of 2-(4-bromo-2-fluoro-5-((tetrahydro-2H-pyran-2-yloxy)methyl)phenoxy)tetrahydro-2H-pyran (6.31 g, 16.2 mmol) in anhydrous THF (13.5 mL) was made before cooling the reaction mixture in a −78° C. bath. Reaction mixture was then treated, drop-wise, with n-BuLi (12.15 mL, 19.45 mmol) and allowed to stir for 1.0 hr before (i-PrO)3B (5.59 mL, 24.3 mmol) was added via syringe. After the addition of (i-PrO)3B, the reaction mixture was warmed to room temperature and allowed to stir for 2 hr before quenching the reaction with equal volume of concentrated NH4Cl(aq) and EtOAc (1:1, 30 mL). The layers were separated and the water phase was further extracted with equal volume of EtOAc before the organic layers were combined and dried over anhydrous Na2SO4 and filtered. The solvent was removed under reduced pressure. The residue was purified by silica gel column using Combiflash to give 6-fluorobenzo[c][1,2]oxaborole-1,5(3H)-diol (2.01 g, 73.93%). 1H-NMR (400 MHz, DMSO-d6) δ (ppm) 4.85 (s, 2H), 6.95 (d, J=5.4 Hz, 1H), 7.36 (d, J=8.1 Hz, 1H), 8.98 (s, 1H), 10.22 (s, 1H).

Provenance & Evidence