反应详情

A solution of 3.0 g of trans-4-(3,4-difluorophenyl)cyclohexanecarboxaldehyde (prepared in accordance with Example 2) and 2.4 g of 2-(1E-propenyl)-1,3-propanediol in 75 ml of toluene was treated with 3 drops of 10 percent (v/v) sulphuric acid and the reaction mixture was heated to boiling for 1.25 hours, whereby moist toluene was distilled off and replaced by fresh toluene. Then, the reaction mixture was neutralized with triethylamine and, after cooling, washed three times with water, dried over sodium sulphate and concentrated. Chromatographic purification of the residue on 100 g of silica gel with hexane/ethyl acetate (vol. 49:1) and repeated recrystallization of the trans/cis mixture from hexane gave 0.8 g of pure trans-5-(1E-propenyl)-2-[trans-4-(3,4-difluoro-phenyl)cyclohexyl]-1,3-dioxane; m.p. (C-N) 96.0° C., cl.p. (N-I) 125.5° C., Δε (115° C.)=12.4.

1. temperaturethe reaction mixture was heated
2. distillationwhereby moist toluene was distilled off
3. temperatureafter cooling
4. washwashed three times with water
5. dry with materialdried over sodium sulphate
6. concentrationconcentrated
7. customChromatographic purification of the residue on 100 g of silica gel with hexane/ethyl acetate (vol. 49:1)
8. customrecrystallization of the trans/cis mixture from hexane