Reaktion #1949931

Reaktionsgleichung

2,2-dimethyl-4(2-methyl-thien-5-yl)-thiochrom-3-en-6-al

Compound U

2,2-dimethyl-4(2-methyl-thien-5-yl)-thiochrom-3-en-6-al

THF

ethyl 4-(diethoxyphosphoryl-3,3-dimethoxypropyl)benzoate

Compound D

ethyl 4-(diethoxyphosphoryl-3,3-dimethoxypropyl)benzoate

lithium diisopropylamide

THF

THF

→

product E

ethyl 4-[1-(2,2-dimethoxyethyl)-2-{1(tol-4-yl)3,4-dihydro-4,4-dimethyl-naphthalen-7-yl}-(E)-ethenyl]-benzoate

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigewas recooled to −78° C.
2. 2
   TemperaturThe reaction mixture was gradually warmed to −10° C. over 2 hours
3. 3
   SonstigeThen the reaction was quenched
4. 4
   workup.ADDITIONby adding water (5 mL) and ethyl acetate (70 mL)
5. 5
   WaschenThe organic layer was washed with brine (10 mL)
6. 6
   Sonstigedried
7. 7
   Sonstigethe solvent was removed by distillation

Vorschrift

To a cold (−78° C.) solution of ethyl 4-(diethoxyphosphoryl-3,3-dimethoxypropyl)benzoate (Compound D, 500 mg, 1.29 mmol) in THF (2.5 mL) was added freshly prepared lithium diisopropylamide in THF (1.5 mmol). The mixture was allowed to warm to −5° C. over a period of 1 hour and 40 minutes. The reaction mixture was recooled to −78° C. and 2,2-dimethyl-4(2-methyl-thien-5-yl)-thiochrom-3-en-6-al (Compound U, 180 mg, 0.58 mmol) in THF (2 mL) was added. The reaction mixture was gradually warmed to −10° C. over 2 hours. Then the reaction was quenched by adding water (5 mL) and ethyl acetate (70 mL). The organic layer was washed with brine (10 mL) dried and the solvent was removed by distillation. The product E and Z isomers were isolated by column chromatography. The required E (minor) isomer (45 mg) was dissolved in dichloromethane (5 mL) and cooled to −78° C. To this solution SnCl4 (110 mg, 0.42 mmol) in dichloromethane (1 mL) was added dropwise, the reaction mixture was gradually warmed to −30° C. over 30 min. The reaction was quenched by adding ethanol (0.5 mL), water (5 mL) and ethyl acetate (75 mL). The organic layer was washed with brine (10 mL), dried and the solvent was removed by distillation. The title compound was isolated as a white solid after column chromatography.

Quelle