反应详情

温度

-78 °C

To a stirring suspension of compound 23G (600 mg, 1.96 mmol) in anhydrous THF (10 mL) at rt was added DMPU (4 mL). The resulting clear solution was cooled to −78° C., then a 2.0 M solution of LDA in THF (1.96 mL, 3.92 mmol) was added slowly so that the reaction temperature was maintained below −72° C. The resulting dark brown solution was stirred at −78° C. for 30 min, then iodomethane (0.36 mL, 3.92 mmol) was added dropwise. After addition, the reaction was stirred at −78° C. for 30 min, then at 0° C. for 3 h. The reaction was quenched with 5% aqueous KHSO4 and extracted with EtOAc (3×). The combined extracts were washed with brine, dried (Na2SO4), filtered and concentrated. The residue was chromatographed (silica gel), eluting with 1% MeOH in EtOAc/CH2Cl2 (1:9) to give a mixture of compound 25 and compound 26 (150 mg), which was further purified using preparative HPLC to afford the title compound (20 mg). HPLC: 99% at 4.40, 5.20 min (retention time) (Conditions: Zorbax SB C18 (4.6×75 mm); Eluted with 0% to 100% B, 8 min gradient. (A=90% H2O-10% MeOH-0.1% H3PO4 and B=10% H2O-90% MeOH-0.1% H3PO4); Flow rate at 2.5 mL/min. UV detection at 220 nm). Chiral HPLC: retention time=7.9 min (99%); Conditions: OD (4.6×250 mm); Eluted with 20% isopropanol in hexane for 30 min at 1 mL/min, MS (ES) m/z 320 [M+1]+.

1. temperaturewas maintained below −72° C
2. additionAfter addition
3. stirringthe reaction was stirred at −78° C. for 30 min
4. waitat 0° C. for 3 h
5. customThe reaction was quenched with 5% aqueous KHSO4
6. extractionextracted with EtOAc (3×)
7. washThe combined extracts were washed with brine
8. dry with materialdried (Na2SO4)
9. filtrationfiltered
10. concentrationconcentrated
11. customThe residue was chromatographed (silica gel)
12. washeluting with 1% MeOH in EtOAc/CH2Cl2 (1:9)
13. customto give
14. customwas further purified