4-Piperidinecarboxylic acid → 1-Carbobenzoxy-4-piperidinecarboxylic Acid

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Reaction Steps

Benzyl chloroformate (16.4 mL, 115 mmol) in toluene (50 mL) was added dropwise to a stirred solution of 12.9 g (100 mmol) of isonipecotic acid (Aldrich) and 21.0 g (250 mmol) of sodium bicarbonate in 200 mL of water. After 14 h, the mixture was extracted with ether (3×50 ml) and the ether layers were discarded. The aqueous layer was acidified with conc. HCl to pH 2, causing the product to precipitate. The product was partitioned into ethyl acetate (3×50 mL) and the combined organic layers were washed with brine, dried over magnesium sulfate, and concentrated in vacuo to yield 22.6 g (86%) of N-CBZ-isonipecotic acid as a viscous oil.

Provenance & Evidence