Reacción #66652

Ecuación de reacción

NH4Cl

cyclohexyl-(3-methoxy-benzylidene)-amine

THF

Iodoethane

HCl

THF

2,2,6,6-tetramethylpiperidine

n-butyllithium

THF

→

2-ethyl-3-methoxy benzaldehyde

Rendimiento 63.0%

Disolventes

H2O

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturadrop-wise maintaining the internal temperature below −10° C
2. 2
   TemperaturaAfter 1 h the solution was cooled to −78° C
3. 3
   Temperaturato warm to rt over 45 min
4. 4
   Extracciónextracted with Et2O
5. 5
   LavadoThe combined organics were washed with H2O
6. 6
   Lavadowashed with brine
7. 7
   Secadodried over MgSO4
8. 8
   Filtraciónfiltered
9. 9
   Concentraciónconcentrated in vacuo
10. 10
    Otroto give a crude imine as an oil
11. 11
    TemperaturaAfter 2 the solution was cooled
12. 12
    Extracciónthe mixture was extracted with ethyl acetate
13. 13
    LavadoThe combined organics were washed with H2O
14. 14
    Lavadowashed with brine
15. 15
    Secadodried over Na2SO4
16. 16
    Filtraciónfiltered
17. 17
    Concentraciónconcentrated in vacuo
18. 18
    Otroto give a crude oil
19. 19
    OtroPurification via flash chromatography (98:2 hexane/ethyl acetate)

Procedimiento

To a solution of 2,2,6,6-tetramethylpiperidine (4.67 g, 33 mmol) in 75 ml THF at −15° C. was added n-butyllithium (12.6 ml, 32 mmol, 2.5 in hexanes) drop-wise maintaining the internal temperature below −10° C. After 15 min a solution of cyclohexyl-(3-methoxy-benzylidene)-amine (3.259 g, 15.0 mmol) in 5.0 ml THF was added and the solution was allowed to stir at −15° C. After 1 h the solution was cooled to −78° C. Iodoethane (11.9 ml, 150 mmol) was added in one portion and the solution was allowed to warm to rt over 45 min, poured into 10% NH4Cl, and extracted with Et2O. The combined organics were washed with H2O, washed with brine, dried over MgSO4, filtered and concentrated in vacuo to give a crude imine as an oil. The oil was taken up in 90 ml of THF and HCl (22 ml, 89 mmol, 4.0 M) and warmed to reflux. After 2 the solution was cooled. H2O was added and the mixture was extracted with ethyl acetate. The combined organics were washed with H2O, washed with brine, dried over Na2SO4, filtered and concentrated in vacuo to give a crude oil. Purification via flash chromatography (98:2 hexane/ethyl acetate) gave 2-ethyl-3-methoxy benzaldehyde (1.543 g, 63%, 2 steps) as a clear oil.

Fuente