反应详情

A mixture of THF (2.2 ml), methanol (4.4 ml) and triethylborane (1M in THF) (8.52 ml) was stirred at room temperature for one hour in an argon atmosphere. A solution of 1-ethyl 6-tert.-butyl 2-hydroxy-4-oxoadipate (1.85 g, 7.1 mmol) in THF (2 ml) was dropwise added to the above boran solution at room temperature. After stirring at room temperature for 2 hours and cooling the mixture to -78° C., sodium borohydride (229 mg, 6.1 mmol) was added in one portion, followed by stirring at -78° C. for 2 hours. After dropwise adding acetyl chloride (0.26 ml) to the reaction solution at -78° C., the solution was stirred for additional 30 minutes at room temperature. After evaporating methanol off under reduced pressure, methanol (30 ml) was added to the mixture and again methanol was evaporated off under reduced pressure. After adding methylene chloride (20 ml) and water (20 ml), pH of the mixture was adjusted to 6 with 1N hydrochloric acid, and mixture was separated. The aqueous layer was extracted with methylene chloride twice (each 50 ml), and organic layers were combined and washed with water (30 ml). After drying the organic solution over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure. The residue was subjected to silica gel column chromatography (hexane:acetone=5:1) to give pure 1-ethyl 6-tert.-butyl 2,4-dihydroxyadipate (1.76 g, 6.73 mmol). Yield, 95 %.

1. stirringAfter stirring at room temperature for 2 hours
2. temperaturecooling the mixture to -78° C.
3. stirringby stirring at -78° C. for 2 hours
4. customAfter evaporating methanol off under reduced pressure, methanol (30 ml)
5. additionwas added to the mixture and again methanol
6. customwas evaporated off under reduced pressure
7. additionAfter adding methylene chloride (20 ml) and water (20 ml)
8. customwas separated
9. extractionThe aqueous layer was extracted with methylene chloride twice (each 50 ml), and organic layers
10. washwashed with water (30 ml)
11. dry with materialAfter drying the organic solution over anhydrous sodium sulfate
12. concentrationthe solvent was concentrated under reduced pressure