Biocatalytic Formal Regio- and Enantioselective Markovnikov Hydroamination of Aryl Alkenes to Chiral Amines

Enantiomerically pure amines are essential intermediates for a variety of prescribed drugs, pure merchandise, and bioactive compounds. Uneven intermolecular hydroamination of alkenes is likely one of the most atom-economical strategies for the synthesis of chiral amines. Nevertheless, the direct stereoselective hydroamination of alkenes stays a major problem. Herein, we developed a novel totally biocatalytic system to allow the direct stereoselective hydroamination of aryl alkenes to supply chiral amines. The method entails sequential alkene uneven hydration catalyzed by a hydratase (HD), adopted by in situ oxidation of alcohol into ketone by two enantiocomplemetary alcohol dehydrogenases (ADHs), and eventually, enantioselective transformation of ketone into enantiomerically pure amine by a ω-transaminase (TA). The addition of lactate dehydrogenase (LDH) facilitated the connection between alcohol oxidation and pyruvate discount, making the cascade response redox self-sufficient and driving the method in the direction of the specified goal product. In vitro cascade biocatalysis for uneven hydroamination of 4 hydroxystyrenes 1a-f was first investigated by utilizing the mixed enzymes (HD/ADHs/LDH/TA) with hint quantity of NAD+ (0.05 mM) and pyridoxal-5’-phosphate (PLP) (0.1 mM), affording each enantiomers of amines 4a-f in 30-90% conversions and >99% ee. Moreover, whole-cell-based cascade biocatalysis was achieved by utilizing the constructed recombinant Escherichia coli cells co-expressing the 5 enzymes with out further NAD+ cofactor, (R)- and (S)-amines 4a−f may very well be obtained in 35−93% conversions and >99% ee. Lastly, the preparative experiments have been demonstrated by utilizing the whole-cell biocatalyst E. coli (RFM-ERR-CB) and E. coli (RFC-ERR-CB) with substrate 1a, affording (S)-4a and (R)-4a in 54.8% and 59.2% yields and >99% ee. This analysis achievement offers a excessive selective, excessive atom-economical, inexperienced and sustainable technique for synthesizing chiral amines from alkenes through formal alkene uneven hydroamination.