Asymmetric Synthesis of Chiral Halogenated Amines using Amine Transaminases

摘要

Amine transaminases (ATAs) are versatile and industrially relevant biocatalysts that catalyze the transfer of an amine group from a donor to an acceptor molecule. Asymmetric synthesis from a prochiral ketone is the most preferred route to the desired amine product, as it is obtainable in a theoretical yield of 100%. In addition to the requirement of active and enantioselective ATAs, the choice of a suitable amine donor is also important to save costs and to avoid additional enzymes to shift the equilibrium and/or to recycle the cofactors. In this work, we identified suitable (R)- and (S)-ATAs from Aspergillus fumigatus and Silicibacter pomeroyi, respectively, to afford a set of halogen-substituted derivatives of brominated or chlorinated 1-phenyl-2-propanamine, 4-phenylbutan-2-amine, and 1-(3-pyridinyl)ethanamine. Optimization of the donor-acceptor ratio enabled application of isopropylamine as an amine donor, which resulted in high conversions and amines with 73-99%ee.