反应详情

To a solution of diisopropylamine (14 mL, 100 mmol) in THF at 0° C. was added n-butyllithium (2.5 M in hexane, 40 mL, 100 mmol) over 10 min. The mixture was stirred at RT for 30 min., and then added via cannula to a −78° C. solution of dimethyl malate F-1 (7.71 g, 47.6 mmol) in THF (130 mL). The mixture was warmed to −20° C. over 2 h, and then cooled to −78° C. Crotyl bromide (8.1 g, 60 mmol) was added, then the mixture was allowed to warm to room temperature and then stirred overnight. The solution was then cooled to −10° C. and quenched with NH4Cl (10%, 100 mL). The THF was removed and the residue extracted with ethyl acetate (2×200 mL). The combined organic layers were washed with HCl (1N, 3×50 mL), saturated aqueous sodium bicarbonate (3×50 mL), and brine, then dried over Na2SO4. The solution was filtered and concentrated to give a residue, which was purified on silica gel (ethyl acetate/hexane 1:4) to afford (2S,3R)-3-(2-butenyl)-2-hydroxysuccinic dimethyl ester F-2 (2.5 g, 24%).

1. temperatureThe mixture was warmed to −20° C. over 2 h
2. temperaturecooled to −78° C
3. temperatureto warm to room temperature
4. stirringstirred overnight
5. temperatureThe solution was then cooled to −10° C.
6. customquenched with NH4Cl (10%, 100 mL)
7. customThe THF was removed
8. extractionthe residue extracted with ethyl acetate (2×200 mL)
9. washThe combined organic layers were washed with HCl (1N, 3×50 mL), saturated aqueous sodium bicarbonate (3×50 mL), and brine
10. dry with materialdried over Na2SO4
11. filtrationThe solution was filtered
12. concentrationconcentrated
13. customto give a residue, which
14. customwas purified on silica gel (ethyl acetate/hexane 1:4)