反应详情

To a solution of 2.054 g (5.0 mmol) of 3-benzylamino-2-(1-hydroxyethyl)-5-trimethylsilyl-4-pentinic acid phenylthio ester dissolved in 40 ml of THF was added 3 ml of 4N potassium hydroxide and the mixture was stirred at room temperature for 3 hours. The resultant was neutralised with 2N hydrochloric acid and extracted with ethyl acetate six times while conducting salting out. The extract was dried with anhydrous magnesium sulfate and concentrated. To the concentrate were added 250 ml of acetonitrile and then 1.57 g (6.0 mmol) of triphenylphosphine and the mixture was vigorously stirred under reflux condition, to which a solution of 1.32 g (6.0 mmol) of 2,2'-dipyridyldisulfide in 50 ml of acetonitrile was added dropwise for 40 minutes. After reflux for 1 hour, the reaction solution was concentrated and purified twice with 50 g of silica-gel chromatography (developer methylene chloride→diethyl ether) and then with 50 g of silica-gel chromatography (developer hexane:diethyl ether 1:4) to give 801 mg of trans-form and 62 mg of cis-form of 1-benzyl-4-ethynyl-3-(1-hydroxyethyl)-2-azetidinone.

1. extractionextracted with ethyl acetate six times
2. dry with materialThe extract was dried with anhydrous magnesium sulfate
3. concentrationconcentrated
4. additionTo the concentrate were added 250 ml of acetonitrile
5. temperatureunder reflux condition
6. temperatureAfter reflux for 1 hour
7. concentrationthe reaction solution was concentrated
8. custompurified twice with 50 g of silica-gel chromatography (developer methylene chloride→diethyl ether)