Water → 2-[2-(Difluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

Temperature

-78 °C

To a solution of 1-bromo-2-difluoromethyl-benzene (19.8 g, 95.7 mmol) in dry THF (200 ml) at −78° C. under a nitrogen atmosphere was added 2.5 M n-BuLi in hexanes (42 ml, 105 mmol) slowly. After completion of the addition, the resulting dark solution was stirred for an additional hour at −78° C. Subsequently, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (25 ml, 123 mmol) was added, and the solution was slowly warmed to room temperature. After stirring overnight at room temperature under a nitrogen atmosphere the solution was poured into 400 ml water. Ethyl acetate (300 ml) was added and the layers were separated. The aqueous layer was extracted twice with ethyl acetate (150 ml and 50 ml respectively), and the combined organic layers were washed with water, dried over Na2SO4, filtered, and evaporated to dryness under reduced pressure. The resulting brown oil (21 g) was purified by bulb-to-bulb-distillation at 3×10−3 mbar at 90-95° C. to yield 2-(2-difluoromethyl-phenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (14.4 g, 59%) as a slightly yellow oil.

1. additionAfter completion of the addition
2. temperaturethe solution was slowly warmed to room temperature
3. stirringAfter stirring overnight at room temperature under a nitrogen atmosphere the solution
4. customthe layers were separated
5. extractionThe aqueous layer was extracted twice with ethyl acetate (150 ml and 50 ml respectively), and the combined organic layers
6. washwere washed with water
7. dry with materialdried over Na2SO4
8. filtrationfiltered
9. customevaporated to dryness under reduced pressure
10. distillationThe resulting brown oil (21 g) was purified by bulb-to-bulb-distillation at 3×10−3 mbar at 90-95° C.

ORD record

ord-a8c9675a47df423480e41bba24ffaee8

Source dataset

uspto-grants-2012_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08158637B2