反应详情

15 g (20 mmol) of 34 were dissolved in 500 ml of MeOH in a 1 l round-bottomed flask, treated with 324 mg (6 mmol) of NaOMe and stirred at room-temp. overnight with exclusion of water (TLC checking, AcOEt/n-heptane 1:1). Amberlite IR-120 was added to the resulting suspension until the pH was <7. The solid was dissolved in the presence of heat, filtered off hot from the ion exchanger and washed with MeOH. After removing the solvent, the residue was co-evaporated twice using 150 ml of water each time. This yielded 9 g of crude product, which was heated under reflux in 90 ml of MeOH for 10 min. After cooling to room temp., the mixture was treated with 60 ml of Et2O and stored overnight at 4° C. Filtration, washing with Et2O and drying in an oil pump vacuum yielded 7.8 g (93%) of 35.

1. customovernight
2. additionAmberlite IR-120 was added to the resulting suspension until the pH was <7
3. dissolutionThe solid was dissolved in the presence
4. temperatureof heat
5. filtrationfiltered off hot from the ion exchanger
6. washwashed with MeOH
7. customAfter removing the solvent
8. temperatureThis yielded 9 g of crude product, which was heated
9. temperatureunder reflux in 90 ml of MeOH for 10 min
10. temperatureAfter cooling to room temp.
11. additionthe mixture was treated with 60 ml of Et2O
12. filtrationFiltration
13. washwashing with Et2O
14. customdrying in an oil pump vacuum