Ethyl valerimidate

Ethyl valerimidate Sodium cyanide Triethylamine Valeryl chloride Tributyltin azide... 

Ethyl valerimidate hydrochloride is prepared according to Mac Elvain (J. Amer. Chem. Soc., 1942, 64, 1825-1827) and then freed from its hydrochloride by reaction with potassium carbonate and extraction with CH2CI2. 

The ethyl ester of 1-aminocyclopentanecarboxylic acid (1.57 g) and ethyl valerimidate (1.56 g) are dissolved in 12 ml of xylene containing 6 drops of acetic acid. After refluxing for 6.5 h, the reaction medium is concentrated under vacuum, the residue is chromatographed on silica gel using a chloroform/methanol/acetic acid mixture (94/4/2 v/v/v) as the eluent. The fraction containing the expected product is evaporated several times in the presence of xylene and then benzene in order to remove the acetic acid. 1.91 g of 2-n-butyl-4-spirocyclopentane-2-imidazolin-5-one are obtained in the form of a thick oil. 

Unlabelled 349 has been synthesized by treatment of ethyl valerimidate hydrochloride with 1,3-dihydroxyacetone in ammonia331 (equation 150). 

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