反应详情

3.0 g of 4'-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)propenyl]-acetophenone (prepared as described in Example 22) dissolved in 40 ml of benzene are treated with a catalytic amount of p-toluenesulphonic acid and 0.6 g of ethyleneglycol and warmed in a Dean-Stark apparatus, the water formed being concurrently separated off. After heating under reflux for 2 days, the mixture is cooled down, introduced into ice/saturated sodium bicarbonate solution and exhaustively extracted with ether. The ether extract is washed twice with a saturated sodium chloride solution, dried over sodium sulphate and evaporated under reduced pressure to remove the solvent. The oily residue is purified by adsorption on silica gel using hexane/ether (9:1) for the elution. The 2-methyl-2-[p-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)propenyl]-phenyl]-1,3-dioxolane obtained from the eluate melts at 122°-123° C. after recrystallisation from ether.

1. temperaturewarmed in a Dean-Stark apparatus
2. custombeing concurrently separated off
3. temperatureAfter heating
4. temperatureunder reflux for 2 days
5. temperaturethe mixture is cooled down
6. additionintroduced into ice/saturated sodium bicarbonate solution
7. extractionexhaustively extracted with ether
8. extractionThe ether extract
9. washis washed twice with a saturated sodium chloride solution
10. dry with materialdried over sodium sulphate
11. customevaporated under reduced pressure
12. customto remove the solvent
13. customThe oily residue is purified by adsorption on silica gel
14. washfor the elution