Hydrochloric Acid → (-)-3-(3,4-difluorophenyl)-3-(2-hydroxyethyl)pyrrolidine(R,R)-di-p-anisoyltartaric acid salt

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Reaction Steps

Combine (R,R)-di-p-anisoyltartaric acid (0.93 g, 2.2 mmol) and aqueous 12M hydrochloric acid solution (0.19 mL, 2.28 mmol) in water/methanol (10 mL)/(10 mL). Heat to reflux. Add dropwise, a solution of 3-(3,4-difluorophenyl)-3-(2-hydroxyethyl)pyrrolidine (0 g, 4.4 mmol) in methanol (10 mL). After 15 minutes, slowly cool to ambient temperatures Filter the solid that forms and rinse with water to give (-)-3-(3,4-difluorophenyl)-3-(2-hydroxyethyl)pyrrolidine (R,R)-di-p-anisoyltartaric acid salt. [α]2D0 =-25.1 (c=1.02, dimethylsulfoxide). Analysis on HPLC, on an analytical sample of the free amine obtained by extractions using a CHIRALPAK AD 25 cm×0.46 cm column eluting with pentane/methanol/triethylamine (80/10/0.1) with a flow rate of 1.0 mL/minute indicates an enantiomeric excess of 97.8%, (97.8% ee), retention time 19.0 minutes for the 3,4,5-trimethoxybenzamide prepared from the (-)-isomer of the (R,R)-di-p-anisoyltartaric acid salt, retention time 12.5 minutes for the 3,4,5-trimethoxybenzamide prepared from the (+)-isomer of the (R,R)-di-p-anisoyltartaric acid salt.

Provenance & Evidence