A solution containing 6.0 g of periodic acid and chromium trioxide (13 mg) in wet acetonitrile (60 mL; 0.75 volume % water) was prepared. A portion of this solution (15 mL) was added dropwise to a solution of (3S,5R)-3-(4-benzyloxyphenyl)-5-hydroxymethyl-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (1.02 g, 2.57 mmol) in wet acetonitrile (15 mL; 0.75 volume % water) at 0° C. The reaction mixture was stirred at 0° C. for 2 hours. At this time, more of the periodic acid/chromium trioxide solution (5 mL) was added. Stirring at 0° C. was continued for an additional 1 hour. After quenching with a solution of dibasic sodium phosphate (720 mg) in water (12 mL), the mixture was extracted twice with diethyl ether. The combined organic extracts were washed with aqueous sodium bisulfite solution (440 mg in 10 mL water) and brine. After drying over MgSO4, the solvent was evaporated to provide a yellow solid that was taken up in methylene chloride (100 mL) and cooled in an ice bath. Hydrogen chloride gas was bubbled through the cold solution for 2 minutes and the resulting mixture was stirred at 0° C. for 1 hour. The solvent and HCl were evaporated to afford a solid from which the title compound, 226 mg (28%) was isolated by trituration with a mixture of methylene chloride, diethyl ether and ethyl acetate. The trituration filtrate was dissolved in aqueous saturated NaHCO3 solution and washed twice with diethyl ether. After careful acidification with aqueous 6M HCl solution, the aqueous layer was extracted twice with ethyl acetate. The combined organic layers were washed with brine, dried over MgSO4 and concentrated to provide more of the title compound, 123 mg (15%).
