Sulfuric Acid → Methyl (3S,4R)-1-benzyl-4-(4-chlorophenyl)pyrrolidine-3-carboxylate

Participants

Reaction Steps

To a solution of (3R,4R)-1-benzyl-4-(4-chloro-phenyl)-pyrrolidine-3-carboxylic acid methyl ester (72.74 g, 220.5 mmol) in methanol (730 mL) was added sodium methylate solution (5.4 M methanol, 81.7 mL, 441.1 mmol). The reaction mixture was stirred for 116 h at ambient temperature (after 17.5 h further sodium methylate solution (5.4 M in methanol, 20.4 mL, 110.3 mmol) was added). It was set to pH=1 by addition of sulfuric acid (26.13 mL, 463.1 mmol) and stirred at 60° C. for 19 h. The resulting suspension was cooled to 0° C., tert-butylmethylether (1.6 L) was added and the solution was set to pH=9 with aqueous sodium carbonate (1 M, 440 mL). The aqueous layer was separated and extracted with further tert-butylmethylether (410 mL). The organic layers were washed with brine (310 mL), combined and dried over sodium sulfate. Concentration and filtration over silicagel (heptane: ethyl acetate=80:20) afforded the title compound (62.82 g, 86%) as a light yellow oil. MS m/e: 330.3/332.3 [M+H]+.

Provenance & Evidence