Dimethyl Sulfoxide → 1-tert-butyl 2-methyl (2S)-4-oxopyrrolidine-1,2-dicarboxylate

Participants

Reaction Steps

A solution of 3.5 mL (40.2 mmol) of oxalyl chloride in 20 mL of CH2Cl2 was cooled in a −78° C. bath and 3.5 mL (49.3 mmol) of dry DMSO was added. After 30 min, a solution of 5.31 g (23 mmol) of N-(BOC)-4-hydroxy-(L)-proline, methyl ester was added. A precipitate developed during the addition. After 30 min at −78° C., 15 mL (107 mmol) of TEA was added. Another 30 mL of CH2Cl2 was added to the reaction mixture to facilitate stirring and cold bath was removed. After 1.5 hr the solution was partitioned between CH2Cl2 and water. The organic layer was washed with water, 1.2 N HCl, brine then dried over anydrous Na2SO4. The filtrate was concentrated in vacuo and the residue was purified by flash column chromatography on silica gel eluted with a gradient of 20-40% EtOAc/hexane to yield N-(BOC)-4-oxo-(L)-proline, methyl ester (4.56 g).

Provenance & Evidence