反应详情

A mixture of 3,3-bis(4-methoxyphenyl)-2-propenal (22.7 g) and (carbethoxymethylene)triphenylphosphorane (30 g) in carbon tetrachloride (200 mL) was stirred overnight at room temperature and then at reflux for 5 hours to complete the reaction. The crude product (28.4 g) obtained from the usual work up consisted mainly of (E)-5,5-bis(4-methoxyphenyl)-2,4-pentadienoic acid ethyl ester. The crude ester (28.4 g) in a mixture of methanol (200 mL) and 2N sodium hydroxide solution (100 mL) was heated at reflux for 30 minutes, then most of the methanol was distilled from the reaction. The base mixture was cooled, diluted with water (300 mL), extracted with dichloromethane (3×400 mL) and then was poured into a stirred mixture of concentrated hydrochloric acid (50 mL), water (200 mL) and ice (200 mL). The yellow precipitate was filtered off, washed with water and dried. The material was triturated with ether (3×100 ml) to provide 21.5 g of (E)-5,5-bis(4-methoxyphenyl)-2,4-pentadienoic acid, mp 187°-189° C. Crystallization from dichloromethane-hexane furnished the pure acid, mp 189.5°-190.5° C. Anal. Calculated for C19H18O4C: 73.53; H, 5.85 Found: C, 73.34; H, 5.92.

1. temperatureat reflux for 5 hours
2. customthe reaction
3. customThe crude product (28.4 g) obtained from the usual work
4. temperaturewas heated
5. temperatureat reflux for 30 minutes
6. distillationmost of the methanol was distilled from the reaction
7. temperatureThe base mixture was cooled
8. additiondiluted with water (300 mL)
9. extractionextracted with dichloromethane (3×400 mL)
10. additionwas poured into a stirred mixture of concentrated hydrochloric acid (50 mL), water (200 mL) and ice (200 mL)
11. filtrationThe yellow precipitate was filtered off
12. washwashed with water
13. customdried
14. customThe material was triturated with ether (3×100 ml)