Reaction #2075721

Reaction equation

1-chloro-3-fluoro-2-(1-fluoroethyl)benzene

n-butyllithium

diisopropylamine

2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

→

title compound

Yield 94.0%

2-(4-Chloro-2-fluoro-3-(1-fluoroethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

Yield 94.0%

Solvents

THF

hydrochloric acid

tetrahydrofuran THF

Conditions

Workup

1. 1
   Temperaturewarmed to 0° C. for 20 m
2. 2
   Temperaturecooled back to −78° C. for 20 m
3. 3
   Otherat −78° C.
4. 4
   workup.STIRRINGThe resulting dark brown solution was stirred at −78° C. for 2 h
5. 5
   Temperaturethe brown solution was slowly warmed to 23° C. over 20 h
6. 6
   Extractionextracted with dichloromethane three times
7. 7
   OtherThe combined organic layers were dried
8. 8
   Filtrationfiltered
9. 9
   Concentrationconcentrated by rotary evaporation

Procedure

A 2.5 M solution of n-butyllithium (13 mL, 33 mmol) was added to a stirred solution of diisopropylamine (5.0 mL, 35 mmol) in tetrahydrofuran THF (50 mL) at −78° C. The resulting colorless solution was stirred at −78° C. for 20 m, warmed to 0° C. for 20 m, and then cooled back to −78° C. for 20 m. A solution of 1-chloro-3-fluoro-2-(1-fluoroethyl)benzene (4.8 g, 27 mmol, 1.0 equiv) in THF (20 mL) at −78° C. was transferred to the base solution via cannula. The resulting dark brown solution was stirred at −78° C. for 2 h. 2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (8.3 mL, 41 mmol, 1.5 equiv) was added and the brown solution was slowly warmed to 23° C. over 20 h. The reaction mixture was diluted with 0.1M hydrochloric acid (300 mL) and extracted with dichloromethane three times. The combined organic layers were dried, filtered and concentrated by rotary evaporation to afford the title compound as a brown oil that solidified into a semi-solid upon standing (7.7 g, 94% yield). 1H NMR (300 MHz, CDCl3) δ 7.62 (m, 1H), 7.17 (m, 1H), 6.13 (dq, 1H, J=6, 46 Hz), 1.75 (ddd, 3H, J=1, 7, 23 Hz), 1.36 (s, 12 H).

Source