Biocatalytic synthesis of multiple stereogenic elements nonbiaryl atropisomers via simultaneous multichirality control

The synthesis of complex nonbiaryl atropisomers with multiple stereogenic elements remains a significant challenge due to their flexible conformations and rotational freedom. Here, we report an ene-reductase-catalyzed asymmetric reduction strategy that enables control over both central and axial chirality, yielding structurally diverse maleimide atropisomers containing tertiary carbon stereocenters with yields up to 70% yield and outstanding enantioselectivities. Two ene-reductases 12-Oxophytodienoate reductase 1 (OPR1) and Nicotinamide-dependent cyclohexenone reductase (NCR), respectively, demonstrated exceptional stereoselectivity towards halogenated and bulky substrates. Mechanistic studies on OPR1 revealed 22 active-site residues critical for stereocontrol, with saturation mutagenesis identifying key positions that reshape the active site and influence catalytic enantioselectivity. This work highlights the potential of biocatalysis for the efficient synthesis of complex axially chiral molecules and underscores future opportunities in enzyme engineering to expand substrate scope and optimize catalytic efficiency.