反应详情

A solution of 5-(2-oxo-ethyl)-pyrazine-2-carboxylic acid methyl ester (295 mg, 1.42 mmol) and ethylene glycol (100 μL, 1.79 mmol) in benzene (10 mL) was treated with p-toluenesulfonic acid monohydrate (27 mg, 0.142 mmol), and the mixture was heated under reflux with a Dean-Stark condenser for 20 h. The mixture was cooled, diluted with benzene (15 mL), and then washed with a saturated aqueous sodium bicarbonate solution (10 mL) followed by a saturated aqueous sodium chloride solution (10 mL). Each aqueous phase was extracted with a small portion of benzene. The combined organic extracts were dried over sodium sulfate, filtered, and concentrated in vacuo to dryness to afford 5-[1,3]dioxolan-2-ylmethyl-pyrazine-2-carboxylic acid methyl ester as an orange oil (273 mg, 86%).

1. temperaturethe mixture was heated
2. temperatureunder reflux with a Dean-Stark condenser for 20 h
3. temperatureThe mixture was cooled
4. washwashed with a saturated aqueous sodium bicarbonate solution (10 mL)
5. extractionEach aqueous phase was extracted with a small portion of benzene
6. dry with materialThe combined organic extracts were dried over sodium sulfate
7. filtrationfiltered
8. concentrationconcentrated in vacuo to dryness