反应详情

A mixture of 0.43 g (1 mmole) of rac-3,4-dihydro-2,5,7,8-tetramethyl-6-(phenylmethoxy)-2H-1-benzopyran-2-ylpropanedioic acid dimethyl ester, 0.56 g (10 mmoles) of potassium hydroxide, and 25 ml of 9:1 ethylene glycol-water is stirred and refluxed for 8 hr. The mixture is cooled, diluted with water, and extracted with ether (the ether extract is discarded). The aqueous, alkaline solution is acidified with 3NHCl and the acid product isolated by ether extraction. The ether extracts are combined, washed with water and brine, dried (MgSO4), filtered and concentrated in vacuo. Recrystallization of the residue from aqueous ethanol gives rac-3,4-dihydro-2,5,7,8-tetramethyl-6-(phenylmethoxy)-2H-1-benzopyran-2-acetic acid which can be converted to Vitamin E by the procedures in Helv. Chim Acta 61, 837 (1978); Helv. Chim. Acta 59, 290(1976) and Helv. Chim. Acta 64, 1158 (1981).

1. temperaturerefluxed for 8 hr
2. temperatureThe mixture is cooled
3. extractionextracted with ether (the ether
4. extractionextract
5. customisolated by ether extraction
6. washwashed with water and brine
7. dry with materialdried (MgSO4)
8. filtrationfiltered
9. concentrationconcentrated in vacuo
10. customRecrystallization of the residue from aqueous ethanol