L-Alanyl-L-proline → HCID 22822673, compound

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Reaction Steps

Ethyl 5-methyl-2-oxohexanoate (3.44 g) and L-alanyl-L-proline (0.74 g) is stirred in 15 ml of ethanol with 6 g of powdered 4A molecular sieves. Sodium cyanoborohydride (0.23 g) in ethanol is added dropwise over the course of several hours. The ethanol is then removed under vacuum, the product is absorbed on strong acid ion-exchange resin and eluted with 2% pyridine in water to yield 1.08 g. of N-(1-ethoxycarbonyl-4-methylpentyl)-L-alanyl-L-proline. A portion is purified by LH-20 chromatography for spectral analysis. The nmr is in accord with structure. The mass spectrum shows a peak at 414 (silylated molecular ion -15). Chromatography affords the desired isomer.

Provenance & Evidence