Biocatalytic strategy toward asymmetric β-hydroxy nitriles and γ-amino alcohols

A library of 20 bakers' yeast reductases, that are overexpressed in Escherichia coli, were screened against a variety of β-keto nitriles. Enzymes from the aldose reductase and the short chain dehydrogenase family displayed activity toward these substrates. All of the seven substrates were reduced with high enantioselectivities and in some cases both antipodes could be synthesized in high ees. These whole-cell reactions afforded gram quantities of asymmetric compounds that could ultimately lead to scaleable and simple synthesis to new drug analogs of serotonin reuptake inhibitors and β-adrenergic blocking agents.