Sodium borohydride → (3-(3,4-Dimethoxyphenyl)-5-oxopyrrolidin-3-yl)acetic acid ethyl ester

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Reaction Steps

Combined 3-cyano-3-(3,4-dimethoxy-phenyl)-pentanedioic acid diethyl ester (16.8 g, 48.0 mmol), methanol (300 mL) and cobalt (II) chloride hexahydrate (22.8 g, 96.0 mmol). Cooled until the internal temperature reached 10° C. Added portionwise so as to maintain the reaction temperature below 20° C., sodium borohydride (44.2 g, 1.17 mol). After addition was complete, the reaction mixture was allowed to warm to ambient temperature and stirred over the weekend. Concentrated in vacuo to obtain a residue. Partitioned between 1N HCl (800 mL) and dichloromethane (800 mL). The organic layer was extracted with 1N HCl (2×200 mL). The combined aqueous layers were extracted with dichloromethane (3×100 mL). The organic layers were combined, dried over Na2 SO4, filtered, and concentrated in vacuo to obtain a residue. The residue was chromatographed on silica gel eluting with ethyl acetate/methanol (20:1) to obtain the title compound: Rf =0.27 (silica gel, 20:1 ethyl acetate/methanol), mp=116°-118° C. Analysis: calculated for C16H21NO5C 62.53; H 6.89; N 4.56; Found C 62.52; H 6.85; N 4.50.

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