反应详情

Magnesium (0) (400 mg) was suspended in 17 mL of anhydrous diethyl ether, and to the suspension was added 100 μL of 1,2-dibromoethane. 1,3-dibromobenzene (3.8 g, 16.08 mmol) was added at a rate to keep a moderate reflux. After Grignard formation was complete (magnesium consumed and the reaction cooled), 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (0.34 g, 0.80 mmol in 8 mL of anhydrous diethyl ether) was added drop-wise. The reaction was refluxed for 5 h, cooled to room temperature and poured into a separatory funnel with 20 mL of water. The flask was rinsed with 50 mL of diethyl ether and 3 mL of acetic acid (to dissolve the magnesium salts) and added to the seperatory funnel. The layers were separated and the aqueous layer was collected and concentrated in vacuo. The white pasty solid was dissolved in 15 mL of pyridine and 10 mL of acetic anhydride. After 20 h at room temperate the reaction was poured into 150 mL of water and extracted into dichloromethane (3×150 mL). The organic layers were combine, washed with 1 N hydrochloric acid (3×50 mL), dried over sodium sulfate, filtered, concentrated and purified by column chromatography (12 g silica gel, 5% to 95% ethyl acetate-hexane) to afford (1S)-2,3,4,6-tetra-O-acetyl-1,5-anhydro-1-(3-bromophenyl)-D-glucitol (0.178 g, 0.36 mmol, 45% yield) as a white foam; Rf 0.4 (40% ethyl acetate-hexane); 1H NMR (300 MHz, CDCl3) δ 7.44 (m, 2H) 7.25 (m, 2H), 5.27-5.35 (m, 1H), 5.21 (t, J=9.6 Hz, 1H), 5.03 (t, J=9.7 Hz, 1H), 4.36 (d, J=9.9 Hz, 1H), 4.23-4.32 (m, 1H) 4.08-4.18 (m, 1H) 3.80-3.85 (m, 1H) 2.09 (s, 3H), 2.06 (s, 3H), 1.99 (s, 3H), 1.84 (s, 3H) ppm; MS [M+H]+ 488.4.

1. customconsumed
2. additionwas added drop-wise
3. temperatureThe reaction was refluxed for 5 h
4. washThe flask was rinsed with 50 mL of diethyl ether and 3 mL of acetic acid (
5. dissolutionto dissolve the magnesium salts) and
6. additionadded to the seperatory funnel
7. customThe layers were separated
8. customthe aqueous layer was collected
9. concentrationconcentrated in vacuo
10. dissolutionThe white pasty solid was dissolved in 15 mL of pyridine
11. additionthe reaction was poured into 150 mL of water
12. extractionextracted into dichloromethane (3×150 mL)
13. washwashed with 1 N hydrochloric acid (3×50 mL)
14. dry with materialdried over sodium sulfate
15. filtrationfiltered
16. concentrationconcentrated
17. custompurified by column chromatography (12 g silica gel, 5% to 95% ethyl acetate-hexane)