反应详情

温度

-78 °C

To a −78° C. solution of (R)-3-tert-butyl 4-methyl 2,2-dimethyloxazolidine-3,4-dicarboxylate (Intermediate 181, 18.80 g, 72.50 mmol) in toluene (153 mL) was dropwise (via addition funnel) added DIBAL-H (1.0 M in toluene) (116 ml, 116.01 mmol) over 1.5 hours. The reaction mixture was stirred at −78° C. for 2 hours under nitrogen atmosphere. The cold reaction mixture was treated with 38 mL MeOH (˜1.91 M) and then poured 750 mL cold 1N HCl (˜0.09M) into reaction mixture, removed reaction mixture from −78° C. bath, transferred to separatory funnel and extracted with ethyl acetate. The organic layers were dried over magnesium sulfate, filtered, concentrated. Due to a difficult separation required two silica gel chromatography columns (0%-50% ethyl acetate/hexanes) to afford the title compound as a colorless oily solid (10.2 g, 61%).

1. customTo a −78° C.
2. addition(via addition funnel)
3. customThe cold reaction mixture
4. custominto reaction mixture
5. customremoved
6. customreaction mixture from −78° C. bath
7. customtransferred to separatory funnel
8. extractionextracted with ethyl acetate
9. dry with materialThe organic layers were dried over magnesium sulfate
10. filtrationfiltered
11. concentrationconcentrated
12. customDue to a difficult separation