Reacción #79371

Ecuación de reacción

ethyl 5-bromo-2,2-dimethylpentanoate

LiBH4

methanol

→

product

Rendimiento 101.5%

5-Bromo-2,2-dimethyl-1-pentanol

Rendimiento 101.5%

Disolventes

methylene chloride

methylene chloride

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.ADDITIONwas added dropwise
2. 2
   Otrothe temperature below 30° C
3. 3
   Temperaturathe solution was heated
4. 4
   Temperaturaunder reflux for 21 h
5. 5
   TemperaturaAfter chilling in an ice-bath
6. 6
   Otrothe reaction was quenched
7. 7
   workup.ADDITIONby adding H2O dropwise (100 mL)
8. 8
   workup.ADDITION2 N HCl (125 mL) was added dropwise
9. 9
   OtroThe layers were separated
10. 10
    Extracciónthe aqueous layer was extracted with an additional methylene chloride (500 mL)
11. 11
    Lavadowashed with 2 N HCl 9300 mL), then sat. NaHCO3 (300 mL)
12. 12
    SecadoAfter drying the organics over Na2SO4
13. 13
    Otrothe solution was evaporated

Procedimiento

Under argon, a suspension of LiBH4 (14.8 g, 646 mmol) in methylene chloride (600 mL) was stirred as methanol (25.6 mL, 20.2 g, 629 mmol) was added dropwise, taking care to keep the temperature below 30° C. To this mixture, a solution of ethyl 5-bromo-2,2-dimethylpentanoate (100.0 g, 392 mmol; prepared according to Kuwahara et al. Chem. Pharm. Bull 1997, 48, 1447) in methylene chloride (200 mL) was added dropwise over 20 minutes, and the solution was heated under reflux for 21 h. After chilling in an ice-bath, the reaction was quenched by adding H2O dropwise (100 mL). After the effervescence stopped, 2 N HCl (125 mL) was added dropwise and the solution was stirred until the effervescence ceased. The procedure was repeated with another portion of 2 N HCI (125 mL). The layers were separated, and the aqueous layer was extracted with an additional methylene chloride (500 mL). The two organic portions were combined and washed with 2 N HCl 9300 mL), then sat. NaHCO3 (300 mL). After drying the organics over Na2SO4, the solution was evaporated to yield the product as a light yellow oil (77.6 g, 91% yield). 1H NMR (d6-DMSO), d (ppm): 4.42 (s, 1H); 3.45 (t, 2 H, J=6.6); 3.08 (s, 2H); 1.84-1.69 (m, 2H); 1.27 (t, 2 H, J=8.3); 0.78 (s, 6H). 13C NMR (d6-DMSO), d (ppm): 69.7, 36.9, 35.7, 34.5, 27.4, 24.0.

Fuente