Reaction #511542

Reaction equation

tert-butyllithium

HCl

vinyl boronic acid

Compound 5b

2-Bromo-5-fluoro-[1-(methoxymethoxy)methyl]benzene

→

11

Yield 30.0%

1,3-Dihydro-5-fluoro-1-vinyl-2,1-benzoxaborole

Yield 30.0%

Solvents

pentane

Water

THF

Conditions

Workup

1. 1
   workup.STIRRINGThe mixture was stirred at −78° C. for 1 h
2. 2
   Temperaturewas warmed up to room temperature
3. 3
   workup.STIRRINGstirred overnight
4. 4
   workup.STIRRINGwas stirred at room temperature for 4 h
5. 5
   OtherTHF was removed under reduced pressure
6. 6
   ExtractionThe residue was extracted with ethyl ether
7. 7
   Washwashed with brine
8. 8
   Dryingdried over magnesium sulfate
9. 9
   Concentrationconcentrated under reduced pressure
10. 10
    OtherThe crude product was purified by flash column chromatography (9:1 hexane/ethyl acetate)

Procedure

Compound 5b (2.0 g, 8.0 mmol) in THF (30 mL) was cooled to −78° C. and tert-butyllithium (9.9 mL, 16.8 mmol) as 1.7 M solution in pentane was added slowly. After stirring at −78° C. for 30 min, dibutyl ester of vinyl boronic acid was added dropwise. The mixture was stirred at −78° C. for 1 h, then was warmed up to room temperature and stirred overnight. Concentrated HCl (4 mL) was added and was stirred at room temperature for 4 h. Water (10 mL) was added and THF was removed under reduced pressure. The residue was extracted with ethyl ether, washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The crude product was purified by flash column chromatography (9:1 hexane/ethyl acetate) to give 11 (383 mg, 30%) as a yellowish oil; 1H NMR (300 MHz, DMSO-d6) δ (ppm) 5.27 (s, 2H), 6.25 (t, J=8.5 Hz, 1H), 6.50 (d, J=9.4 Hz, 2H), 7.06-7.15 (m, 2H), 7.89 (dd, J=5.6, 7.9 Hz, 1H); ESI-MS m/z (M+H)+; HPLC purity: 98.7%; Anal. (C9H8BFO 0.1H2O)C, H.

Source