Cyclohexanecarboxylic acid, 2-(2-(benzylcarbamoyl)ethyl)hydrazide → rac-(2R,5S)-1-benzylpyrrolidine-2,5-dicarboxylic acid

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Reaction Steps

The first step in the preparation of this compound was to prepare diethyl cis-N-benzylpyrrolidine-2,5-dicarboxylate from diethyl meso-α,α'-dibromoadipate (see Example 1) as described by G. Cignarella and G. Nathansohn in J. Org. Chem., 26, p 1500, 1961. Diethyl cis-N-benzylpyrrolidine-2,5-dicarboxylate (103.5 g, 0.340 mole) was then heated in 1 liter concentrated hydrochloric acid at 100° C for 2 hours. Upon cooling, a crystalline solid precipitated. It was isolated by filtration, triturated with acetone-diethyl ether, and recrystallized from ethanol-water to give 41.3 g (49%) of partially hydrated product, melting point 254°-258° C. An infrared spectrum analysis gave λmax.Nujol = 2.95 μ (O--H).

Provenance & Evidence