Benzyl chloroformate → Benzyl 3-pyrroline-1-carboxylate

Participants

Reaction Steps

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.

Provenance & Evidence