反应详情

7-Methyl-1,4-dioxaspiro[4.5]decan-8-one (10.5 g, 62 mmol) was dissolved in methanolic potassium hydroxide solution (10 w/w %, 60 g). To the solution was added dropwise a solution of aqueous formaldehyde solution (37%, 4.6 ml) in methanol (5 ml) under ice-cooling over 20 min, and the mixture was stirred for 30 min. Then, to the reaction mixture were added 1 N hydrochloric acid and saturated aqueous ammonium chloride solution, and the mixture was extracted three times with chloroform. The combined organic layers were dried over magnesium sulfate. Magnesium sulfate was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel chromatography to give the title compound (6.9 g, yield 56%).

1. temperaturecooling over 20 min
2. extractionthe mixture was extracted three times with chloroform
3. dry with materialThe combined organic layers were dried over magnesium sulfate
4. customMagnesium sulfate was removed by filtration
5. concentrationthe filtrate was concentrated under reduced pressure
6. customThe residue was purified by silica gel chromatography