（2s，4r）-1，2-dicarbobenzyloxy-4-hydroxypyrrolidine

100-39-0

13504-85-3

13500-53-3

A solution of triethylamine (15 mmol, 3.98 g) and benzyl bromide (16.5 mmol, 2.82 g) in THF (25 mL) at 0 °C was added to Cbz-L-hydroxyproline. The reaction mixture was stirred at room temperature for 18 hours. After completion of the reaction, the solvent was removed by vacuum evaporation. The residue was dissolved in 50 mL of dichloromethane and washed sequentially with 1N HCl, water, 5% Na2CO3 solution and water. The organic layer was dried with anhydrous Na2SO4, filtered and the solvent evaporated. The residue was purified by silica gel column chromatography (eluent: hexane/ethyl acetate, 2:1) to afford (2S,4R)-1,2-dibenzyloxycarbonyl-4-hydroxypyrrolidine (Compound 3) as a light yellow oil (2.66 g, 50% yield).