反応 #168974

反応方程式

NH4Cl

cyclohexyl-(3-methoxy-benzylidene)-amine

THF

Iodoethane

HCl

THF

2,2,6,6-tetramethylpiperidine

n-butyllithium

THF

→

2-ethyl-3-methoxy benzaldehyde

収率 63.0%

溶媒

H2O

反応条件

後処理

1. 1
   温度drop-wise maintaining the internal temperature below −10° C
2. 2
   温度After 1 h the solution was cooled to −78° C
3. 3
   温度to warm to rt over 45 min
4. 4
   抽出extracted with Et2O
5. 5
   洗浄The combined organics were washed with H2O
6. 6
   洗浄washed with brine
7. 7
   乾燥dried over MgSO4
8. 8
   ろ過filtered
9. 9
   濃縮concentrated in vacuo
10. 10
    その他to give a crude imine as an oil
11. 11
    温度After 2 the solution was cooled
12. 12
    抽出the mixture was extracted with ethyl acetate
13. 13
    洗浄The combined organics were washed with H2O
14. 14
    洗浄washed with brine
15. 15
    乾燥dried over Na2SO4
16. 16
    ろ過filtered
17. 17
    濃縮concentrated in vacuo
18. 18
    その他to give a crude oil
19. 19
    その他Purification via flash chromatography (98:2 hexane/ethyl acetate)

実験手順

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.

出典