反应详情

4-Methylene-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester (12.00 g, 52.80 mmol) was dissolved in MeOH (200 mL) and treated with 4.0 M HCl/dioxane (50 mL). After stirring for 3.5 hours at room temperature, the reaction mixture was concentrated under reduced pressure. The crude residue was dissolved in DCM (200 mL) and treated with DIPEA (22 mL, 127 mmol) and BnOCOCl (9.64 mL, 63.4 mmol). After stirring for 1 hours at room temperature, the reaction mixture was poured into H2O. The aqueous layer was extracted 3× with DCM. The combined organics were dried over MgSO4, filtered and concentrated. The residue was purified by silica column chromatography (10% to 25% EtOAc/hexane) to provide 4-Methylene-pyrrolidine-1,2-dicarboxylic acid 1-benzyl ester 2-methyl ester (8.20 g, 56%).

1. concentrationthe reaction mixture was concentrated under reduced pressure
2. dissolutionThe crude residue was dissolved in DCM (200 mL)
3. stirringAfter stirring for 1 hours at room temperature
4. extractionThe aqueous layer was extracted 3× with DCM
5. dry with materialThe combined organics were dried over MgSO4
6. filtrationfiltered
7. concentrationconcentrated
8. customThe residue was purified by silica column chromatography (10% to 25% EtOAc/hexane)