反応 #2348120

反応方程式

water

3,5-dimethoxybenzaldehyde

4-methoxy-benzyltriphenylphosphonium bromide

n-butyllithium

→

solid

収率 86.0%

5[(E)-2-(4-Hydroxyphenyl)-vinyl]benzene 1,3-diol

収率 86.0%

溶媒

tetrahydrofuran

tetrahydrofuran

反応条件

後処理

1. 1
   workup.STIRRINGthe mixture stirred for 6-15 h
2. 2
   抽出extracted with dichloromethane
3. 3
   洗浄The organic phase was washed with water, and removal of the solvent in vacuo
4. 4
   その他afforded an oil
5. 5
   その他The oil was separated by flash column chromatography (49:1 hexane/ethyl acetate)
6. 6
   洗浄The cis-stilbene eluted first as a clear oil
7. 7
   workup.ADDITIONTo a solution of the trans isomer (3.1. g) in anhydrous dichloromethane (150 mL) at −78° C. was added (dropwise) boron tribromide (1.0 M, 34.5 mL)
8. 8
   workup.STIRRINGthe resulting red solution was stirred under argon for 30 min
9. 9
   workup.ADDITIONThe solution was poured into water
10. 10
    抽出extracted with dichloromethane
11. 11
    洗浄The organic phase was washed with water, and removal of the solvent in vacuo
12. 12
    その他afforded an oil, which
13. 13
    その他was separated by flash column chromatography (1:1 hexane/ethyl acetate)

実験手順

To a solution of 4-methoxy-benzyltriphenylphosphonium bromide (12.5 g) in anhydrous tetrahydrofuran (200 mL) at −78° C. was added n-butyllithium (2.44 M, 1.0 equiv), and the resulting red solution was stirred under argon for 2-4 h. A solution of 3,5-dimethoxybenzaldehyde (4.5 g) in tetrahydrofuran was added dropwise over 30 min and the mixture stirred for 6-15 h. The resulting cream suspension was poured into water and extracted with dichloromethane. The organic phase was washed with water, and removal of the solvent in vacuo afforded an oil. The oil was separated by flash column chromatography (49:1 hexane/ethyl acetate). The cis-stilbene eluted first as a clear oil followed by the trans isomer as a colorless solid or oil. Overall yield: 91%. To a solution of the trans isomer (3.1. g) in anhydrous dichloromethane (150 mL) at −78° C. was added (dropwise) boron tribromide (1.0 M, 34.5 mL), and the resulting red solution was stirred under argon for 30 min. The solution was poured into water and extracted with dichloromethane. The organic phase was washed with water, and removal of the solvent in vacuo afforded an oil, which was separated by flash column chromatography (1:1 hexane/ethyl acetate) to afford a colorless solid (2.26 g, 86%): mp 260° C.

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