Enantioselective biocatalytic hydrolysis of β-aminonitriles to β-amino-amides using Rhodococcus rhodochrous ATCC BAA-870

A range of β-aminonitriles (3-amino-3-phenylpropanenitrile and derivatives) were synthesised by reaction of various benzonitriles with acetonitrile and subsequent reduction of the resulting acrylonitrile products. These compounds were hydrolysed to the corresponding amides using the nitrile biocatalytic activity of Rhodococccus rhodochrous ATCC BAA-870. Results showed that the nitrile hydratase enzyme was enantioselective for these compounds, in particular 3-amino-3-p-tolylpropanenitrile and 3-amino-3-(4-methoxyphenyl)propanenitrile and the corresponding amides (up to 85% in one case). The reactions were performed at pH 9.0 after initial attempts at pH 7.0 were unsuccessful, most likely as a result of protonation of the 3-amino group at the lower pH.

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► β-Aminonitriles were hydrolysed to the amide using R. rhodochrous ATCC BAA-870.
► The nitrile hydratase was enantioselective.
► The nitrile reached 88% ee and the resultant amide 62% ee.
► The substitution on the β-aromatic ring influenced reaction enantioselectivity.
► A pH of 9 was required to reduce the degree of protonation of the 3-amino group.