反应详情

To a solution of diisopropylamine (14 mL, 100 mmol) in THF at 0° C. is added BuLi (2.5 M in hexane, 40 mL, 100 mmol) over 10 minutes. The mixture is stirred at rt for 30 minutes, and then added via cannula to a −78° C. solution of dimethyl malate B-1 (7.71 g, 47.6 mmol) in THF (130 mL). The mixture is warmed to −20° C. over 2 hours, and then cooled to −78° C. Crotyl bromide (8.1 g, 60 mmol) is added, then the mixture is allowed to warm to rt and then stirred overnight. The solution is then cooled to −10° C. and quenched with NH4Cl (10%, 100 mL). The THF is removed and the residue extracted with EtOAc (2×200 mL). The combined organic layers are washed with HCl (1 N, 3×50 mL), saturated aqueous NaHCO3 (3×50 mL), and brine, then dried over Na2SO4. The solution is filtered and concentrated to give a residue, which is purified on silica gel (EtOAc/hexane 1:4) to afford (2S,3R)-3-(2-butenyl)-2-hydroxysuccinic dimethyl ester B-2.

1. temperatureThe mixture is warmed to −20° C. over 2 hours
2. temperaturecooled to −78° C
3. temperatureto warm to rt
4. stirringstirred overnight
5. temperatureThe solution is then cooled to −10° C.
6. customquenched with NH4Cl (10%, 100 mL)
7. customThe THF is removed
8. extractionthe residue extracted with EtOAc (2×200 mL)
9. washThe combined organic layers are washed with HCl (1 N, 3×50 mL), saturated aqueous NaHCO3 (3×50 mL), and brine
10. dry with materialdried over Na2SO4
11. filtrationThe solution is filtered
12. concentrationconcentrated
13. customto give a residue, which
14. customis purified on silica gel (EtOAc/hexane 1:4)