Benzyl chloroformate → Benzyl 3-pyrroline-1-carboxylate

To a solution of 3-pyrroline (1.3 g, 18.8 mmol) and anhyd. potassium carbonate (15.3 g, 144.6 mmol) in methylene chloride (30 mL) was added dropwise benzyl chloroformate (7.4 g, 43.4 mmol) at 0° C. and stirred for 20 min. The reaction mixture was warmed to room temperature and stirred further for 2 hrs. The mixture was washed with cold water (30 mL) and brine (20 mL) and dried (MgSO4). After evaporation of solvents, the residue was purified by flash column chromatography (EtOAc/hexane (1:10)) to give 1-benzyloxycarbonyl-3-pyrroline (3 g, 78%). To a solution of catalytic amount of osmium tetroxide in water (15 mL) and acetone (7 ml) was added N-methylmorpholine 1H2O (479 mg, 3.5 mmol) and 1-benzyloxycarbonyl-3-pyrroline (600 mg, 3.0 mmol), and stirred overnight. To the reaction mixture were added sodium hydrosulfite (0.1 g) and florisil (2 g) and stirred for 30 min. The reaction mixture was filtered and washed with acetone (10 mL×2). The combined organic solution was dried (MgSO4), evaporated, and purified by flash column chromatography (EtOAc/hexane (1:1) -EtOAc only) to give meso-1-benzyloxycarbonyl-3,4-dihydroxypyrrolidine (586 mg, 84%) as an oil.

1. stirringstirred further for 2 hrs
2. washThe mixture was washed with cold water (30 mL) and brine (20 mL)
3. dry with materialdried (MgSO4)
4. customAfter evaporation of solvents
5. customthe residue was purified by flash column chromatography (EtOAc/hexane (1:10))

ORD record

ord-1342ed194a544a35960275845bf8ac87

Source dataset

uspto-grants-1996_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05571909