BORONIC ACID, [4-CHLORO-3-(TRIFLUOROMETHOXY)PHENYL]- synthesis

Yield:902757-07-7 70%

Reaction Conditions:

Stage #1: 4-bromo-1-chloro-2-(trifluoromethyloxy)benzenewith n-butyllithium in tetrahydrofuran;hexanes at -78; for 0.5 h;
Stage #2: triethyl borate in tetrahydrofuran;hexanes at 20; for 2 h;
Stage #3: with hydrogenchloride in tetrahydrofuran;hexanes;water; pH=4;

Steps:

47.e

77-BuLi (2.5 M in hexanes; 6.25 mL, 12.5 mmol) was added dropwise to 4-bromo- l-chloro-2-trifluoromethoxybenzene (3.4 g, 12.3 mmol; see step (d) above) in anhydrous THF (50 mL) at -78 ⁰C. After 30 min, triethylborate (2.1 mL, 12.5 mmol) was added and the mixture was allowed to warm to rt and stirred at it for 2 h. The mixture was poured into water (100 mL), acidified to pH 4 with HCl (aq, 1 M) and extracted with EtOAc (3x50 mL). The combined extracts were washed with brine, dried (Na₂SO₄) and concentrated. The residue was recrystallised from petroleum ether to yield 2.07 g (70%) of the sub-title compound.

References:

WO2006/77367,2006,A1 Location in patent:Page/Page column 135