Enzymatic syntheses of N‐lauroyl‐β‐alanine homologs in organic media

Abstract

AbstractEnyzmatic amidation of the primary amines β‐alanine ethyl ester and 3‐aminopropionitrile with methyl laurate by means of immobilized lipase (Candida antarctica lipase, CAL) resulted in the formation in good yield of N‐lauroyl‐β‐alanine ethyl ester and 3‐(N‐lauroylamino)‐propionitrile, respectively. When 3‐amino‐propionitrile was used as substrate, diisopropyl ether was a suitable solvent. Changing the reaction temperature (12–80°C) did not affect the yields, and room temperature was a suitable temperature for this reaction. In the investigation of reaction conditions, the use of equimolar amounts (5 mmol) of substrate and ester, along with 0.5 g of CAL, in diisopropyl ether gave the best yield (99.3%) after 24 h of incubation at 24°C. The enzyme activity in the amidation reaction did not decrease even after six uses. With β‐alanine ethyl ester hydrochloride as substrate, diisopropyl ether was unsuited as a solvent owing to the low solubility of the substrate in this solvent.In this reaction, the best yield (82.0%) was attained by using dioxane as solvent. CAL achieved higher extents of amide synthesis with long‐chain than with short‐chain ester substrates. The enzyme accepted only nonbulky primary amines as substrates.