Reaktion #172530

Reaktionsgleichung

trimethylborate

Diisopropylamine

n-BuLi

neopentyl glycol

3-hexylthiophene

→

oil

Ausbeute 79.0%

2-(4-hexylthiophen-2-yl)-5,5-dimethyl-1,3,2-dioxaborinane

Ausbeute 79.0%

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added
2. 2
   Temperaturit was cooled down to −78° C.
3. 3
   workup.STIRRINGAfter stirring at −78° C. for 1 h the reaction
4. 4
   Temperaturwas let warm up to room temperature
5. 5
   workup.STIRRINGthe mixture was stirred for 1 h
6. 6
   TemperaturThen, the reaction was cooled down to −78° C.
7. 7
   workup.WAITAfter 10 min
8. 8
   Temperaturthe reaction was warmed up to room temperature
9. 9
   workup.STIRRINGstirred overnight
10. 10
    SonstigeQuenching with 10% HCl/H2O (40 ml)
11. 11
    Extraktionthe aqueous layer was extracted with ether
12. 12
    WaschenThe ether phase was washed with water, brine
13. 13
    Trocknendried over magnesium sulfate
14. 14
    Sonstigethe solvent was removed under vacuum
15. 15
    workup.ADDITION250 ml toluene were added to the remaining oil
16. 16
    SonstigeThe mixture was sparged with argon
17. 17
    Temperaturheated up to 100° C
18. 18
    workup.WAITAfter 24 h
19. 19
    Sonstigethe solvent was removed under reduced pressure
20. 20
    workup.ADDITIONHexanes were added to the remaining residue
21. 21
    Sonstigethe hexanes phase was purified by column chromatography (99:1 to 97:3 hexanes:acetone)

Vorschrift

Diisopropylamine (7 ml, 50 mmol) was dissolved in dry THF (200 ml). The mixture was cooled down to 0° C., at which point n-BuLi (31 ml 1.6 M, 50 mmol) was added. After stirring the mixture at 0° C. for 30 min, it was cooled down to −78° C. and 3-hexylthiophene (8.1 ml, 45 mmol) was added dropwise. After stirring at −78° C. for 1 h the reaction was let warm up to room temperature, and the mixture was stirred for 1 h. Then, the reaction was cooled down to −78° C., and trimethylborate (15 ml, 134 mmol) was added. After 10 min, the reaction was warmed up to room temperature, and stirred overnight. Quenching with 10% HCl/H2O (40 ml) followed, and the aqueous layer was extracted with ether. The ether phase was washed with water, brine, dried over magnesium sulfate and the solvent was removed under vacuum. 250 ml toluene were added to the remaining oil, followed by neopentyl glycol (7.02 g, 67.4 mmol). The mixture was sparged with argon, and heated up to 100° C. After 24 h, the solvent was removed under reduced pressure. Hexanes were added to the remaining residue, and the hexanes phase was purified by column chromatography (99:1 to 97:3 hexanes:acetone). The product was obtained as a colorless oil (9.9 g, 79% yield). 1H-NMR (ppm, CDCl3): 0.85 (3H, t, J=6.24 Hz), 1.00 (6H, s), 1.22-1.33 (6H, m), 1.59 (2H, m), 2.59 (2H, t, J=7.76 Hz), 3.73 (4H, s), 7.13 (1H, s), 7.38 (1H, s); 13C-NMR (ppm, CDCl3), 14.1, 21.9, 22.6, 29.0, 30.1, 30.6, 31.7, 32.0, 72.4, 122.9, 126.5, 137.0, 144.5; ESI-MS (m/z) found: 218.1742 [M+H], calculated: 218.1753.

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