反应详情

To a solution of 1-methyl 6-tert.-butyl 2,4-dihydroxyadipate (4.98 g, 20.01 mmol) in methylene chloride (2 dimethoxypropane (9.6 ml, 78 mmol) and pyridinium p-toluenesulfonate (2.01 g, 8 mmol) were added and stirred under reflux conditions for one hour, followed by further stirring at 40° C. for 3 hours while azeotropically removing methanol with methylene chloride. After concentration under reduced pressure, the residue was dissolved in ethyl acetate and poured in water. Then, the mixture was extracted with ethyl acetate. The organic layers were combined, dried over sodium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography (hexane:acetone=3:1) to give pure 2-methoxycarbonyl-4-tert.-butoxycarbonylmethyl-6,6-dimethyl-1,5-dioxane (4.89 g, 17.01 mmol). Yield, 85 %.

1. concentrationAfter concentration under reduced pressure
2. dissolutionthe residue was dissolved in ethyl acetate
3. additionpoured in water
4. extractionThen, the mixture was extracted with ethyl acetate
5. dry with materialdried over sodium sulfate
6. concentrationconcentrated under reduced pressure