Stereoselectivity of Four (R)‐Selective Transaminases for the Asymmetric Amination of Ketones

Abstract Four ( R )‐ω‐transaminases originating from Hyphomonas neptunium (HN‐ωTA), Aspergillus terreus (AT‐ωTA) and Arthrobacter sp. (ArR‐ωTA), as well as an evolved transaminase (ArRmut11‐ωTA) were successfully employed for the amination of prochiral ketones leading to optically pure ( R )‐amines. The first three transaminases displayed perfect stereoselectivity for the amination of all substrates tested ( ee >99%). Furthermore, the transaminase AT‐ωTA led in most cases to better conversion than ArR‐ωTA and HN‐ωTA using D ‐alanine as amine donor. α‐Tetralone, which was the only substrate not accepted by HN‐ωTA, ArR‐ωTA, and AT‐ωTA, was successfully transformed with perfect enantioselectivity ( ee >99%) into the corresponding optically pure amine employing the variant ArRmut11‐ωTA.