反应详情

Lithium aluminium hydride (1M in ether, 1.2 ml, 1.20 mmol) was placed in a two necked round bottom flask fitted with a reflux condenser and nitrogen inlet. (-)-N-methy-ephedrine (0.23 g, 1.26 mmol) in ether (1 ml) was added dropwise and the solution was heated at reflux for 1 hour then cooled to room temperature. N-Ethyl-2-aminopyridine (0.31g, 2.52 mmol) in ether (1 ml) was added and the bright yellow solution was heated under reflux for a further 1 hour. The solution was cooled to -78° C. and solid (+) narwedine (97% e.e) (0.10 g, 0.35 mmol) was added. The suspension was warmed to 0° C., stirred for 20 hours and then allowed to warm to room temperature over 1 hour. The reaction was quenched 2M potassium carbonate (10 ml). The mixture was extracted into ethyl acetate (2×10 ml) and then the combined organic layer was washed with water (5 ml) and brine (5 ml) and dried over magnesium sulphate. Filtration and evaporation gave an orange oil which was shown by NMR and GC-MS to contain galanthamine and epigalanthamine in a 1:1 mixture. Flash chromatography on silica in dichloromethane-methanol 10:1 yielded (+) galanthamine (98% e.e.) (30% yield) and (+)-epigalanthamine (95% e.e) (26% yield). ##STR3##

1. customfitted with a reflux condenser and nitrogen inlet
2. temperaturethe solution was heated
3. temperatureat reflux for 1 hour
4. temperaturethe bright yellow solution was heated
5. temperatureunder reflux for a further 1 hour
6. temperatureThe solution was cooled to -78° C.
7. temperatureThe suspension was warmed to 0° C.
8. temperatureto warm to room temperature over 1 hour
9. customThe reaction was quenched 2M potassium carbonate (10 ml)
10. extractionThe mixture was extracted into ethyl acetate (2×10 ml)
11. washthe combined organic layer was washed with water (5 ml) and brine (5 ml)
12. dry with materialdried over magnesium sulphate
13. filtrationFiltration and evaporation
14. customgave an orange oil which