Preparation of N-unsubstituted β-ketoamides by Rhodococcus rhodochrous-catalysed hydration of β-ketonitriles

A varied set of N-unsubstituted β-ketoamides, hardly obtainable or non-accessible by non-enzymatic methods, have been synthesized, with good to excellent yields, by the generally fast hydration of the corresponding β-ketonitriles, catalysed by the bacterium Rhodococcus rhodochrous IFO 15564. This bacterium shows nitrile hydratase and amidase activities, the latter being inhibited during its growth phase with diethyl phosphoramidate (DEPA). Optimization of the processes and studies concerning large-scale biotransformations were also carried out. β-Ketoamides exist as keto–enol mixtures whose composition depends on their substituents and varies with solvent polarity.