反应详情

温度

-78 °C

Thioacetal 5 (194 mg, 0.6 mmol, 1 eq.) was dissolved in anhydrous THF (25 mL) and the solution was cooled to −78° C. To the stirred solution 1.54 M n-butyllithium in hexane (545 μL, 0.84 mmol, 1.4 eq.) was added dropwise over a period of 1 min. After 30 second benzyl bromide (356 μL, 513 mg, 3 mmol, 5 eq) was added to the stirred mixture over a period of 30 sec. After the mixture was stirred for 8 min at −78° C. the resulting red, cloudy solution was allowed to warm to room temperature and was stirred. It took about 30 min. The TLC shows one major product and a little (˜5%) of starting material. Saturated NaCl solution was added into the reaction mixture and the solution was extracted with dichloromethane. The organic solution was washed with water twice, dried under MgSO4 and concentrated under vacuum. The oily residue was treated with hexane. One part of the material got solid and the hexane solution was removed. The yellow solid was washed again with hexane and dried under vacuum. The solid crude material was dissolved in dichloromethane (2 mL), methanol (4 mL) and hexane (about 20 mL) was added. The white precipitate was filtered off to give the pure product 100 mg of 26 (40.8%). 1H NMR (CDCl3, TMS, ppm) δ: 7.36 (d, J=8.7 Hz, 2H), 724 (m, 51), 6.88 (d, J=8.7 Hz, 2H), 5.19 (s, 1H), 5.10 (s, 1H), 4.15 (d, J=16.6 Hz, 1H), 3.82 (s, 3H), 3.25 (d, J=16.5 Hz, 1H), 3.15 (s, 3H), 3.11 (5, 1H).

1. temperatureto warm to room temperature
2. stirringwas stirred
3. waitIt took about 30 min
4. extractionthe solution was extracted with dichloromethane
5. washThe organic solution was washed with water twice
6. customdried under MgSO4
7. concentrationconcentrated under vacuum
8. additionThe oily residue was treated with hexane
9. customthe hexane solution was removed
10. washThe yellow solid was washed again with hexane
11. customdried under vacuum
12. dissolutionThe solid crude material was dissolved in dichloromethane (2 mL)
13. additionmethanol (4 mL) and hexane (about 20 mL) was added
14. filtrationThe white precipitate was filtered off