反应详情

A flame-dried 1 L round bottomed flask containing an MTBE solution of 6 (2.8 g, 33 mmol), and 800 mL of THF was chilled by a cold bath at −30° C. (dry ice/30% ethanol in ethylene glycol). The mixture was allowed to stir under nitrogen atmosphere. Distilled triethylamine (12.2 g, 17.0 mL, 120 mmol), and pivaloyl chloride (6.0 g, 6.2 mL, 50 mmol) were added sequentially, and stirring at −30° C. was continued for one hour. LiCl (7.0 g, 170 mmol) was added. After five minutes, (S)-4-phenyloxazolidinone (9.8 g, 60 mmol), and 4-dimethylamino pyridine (408 mg, 3.35 mmol) were added. The whole reaction mixture was allowed to stir overnight at room temperature. The solvents were removed under reduced pressure, and the residue was partitioned between 300 mL of CH2Cl2 and 300 mL water. The aqueous layer was extracted twice with 300 mL portions of CH2Cl2, and the combined organics were dried (Na2SO4), filtered, and concentrated. The residue was chromatographed on silica gel. The initial eluent was 1:1:9 CH2Cl2:ethyl acetate:hexane, followed by elution with 1:3:7 CH2Cl2:ethyl acetate:hexane. The yield of 7 was 7.20 g (31.5 mmol, 95%). Compound 7 is a white solid. mp=118-119° C., [α]D+140.0 (c 1.00, THF).

1. stirringstirring at −30° C.
2. waitAfter five minutes
3. customThe whole reaction mixture
4. stirringto stir overnight at room temperature
5. customThe solvents were removed under reduced pressure
6. customthe residue was partitioned between 300 mL of CH2Cl2 and 300 mL water
7. extractionThe aqueous layer was extracted twice with 300 mL portions of CH2Cl2
8. dry with materialthe combined organics were dried (Na2SO4)
9. filtrationfiltered
10. concentrationconcentrated
11. customThe residue was chromatographed on silica gel
12. washethyl acetate:hexane, followed by elution with 1:3:7 CH2Cl2