Despite the well-established chemical processes for C-D bond formation, the toolbox of enzymatic methodologies for deuterium incorporation has remained underdeveloped. Here we describe a photodecarboxylase from Chlorella variabilis NC64A (CvFAP)-catalyzed approach for the decarboxylative deuteration of various carboxylic acids by employing D2O as a cheap and readily available deuterium source. Divergent protein engineering of WT-CvFAP is implemented using Focused Rational Iterative Site-specific Mutagenesis (FRISM) as a strategy for expanding the substrate scope. Using specific mutants, several series of substrates including different chain length acids, racemic substrates as well as bulky cyclic acids are successfully converted into the deuterated products (>40 examples). In many cases WT-CvFAP fails completely. This approach also enables the enantiocomplementary kinetic resolution of racemic acids to afford chiral deuterated products, which can hardly be accomplished by existing methods. MD simulations explain the results of improved catalytic activity and stereoselectivity of WT CvFAP and mutants.

The reliable design and prediction of enzyme promiscuity to access transformations not observed in nature remains a long‐standing challenge. Herein, we present the first example of an intramolecular stereoselective Stetter reaction catalyzed by benzaldehyde lyase, guided by the rational structure screening of various ThDP‐dependent enzymes using molecular dynamics (MD) simulations. After optimization, high productivity (up to 99 %) and stereoselectivity (up to 99:1 e.r.) for this novel enzyme function was achieved.

Herein, we developed an electronic effect-guided rational design strategy to enhance the enantioselectivity of Candida antarctica lipase B (CALB) mutants towards bulky pyridyl(phenyl) methanols. Compared to W104A mutant previously reported with reversed S-stereoselectivity toward sec-alcohols, three mutants (W104C, W104S and W104T) displayed significant improvement of Senantioselectivity in the kinetic resolution (KR) of various phenyl pyridyl methyl acetates due to the increased electronic effects between pyridyl and polar residues. The electronic effects were also observed when mutating other residues surrounding the stereospecificity pocket of CALB, such as T42A, S47A, A281S or A281C, and can be used to manipulate the stereoselectivity. A series of bulky pyridyl(phenyl) methanols, including S-(4-chlorophenyl)(pyridin-2-yl) methanol (S-CPMA), the intermediate of bepotastine, were obtained in good yields and ee values.

Deuterated unsaturated fragments have gained increasing attention because of their roles in understanding reaction mechanisms and pharmaceutical potentials. Due to the difficulties of the existing synthetic methods, it is highly desirable to develop an effective, highly site selective, and environmentally friendly method to introduce deuterium into unsaturated fragments. Herein, we describe a biocatalytic hydrogen isotope exchange (HIE) reaction of unsaturated fragments to form C­(sp2)–D bonds catalyzed by an engineered ferulic acid decarboxylase from Aspergillus niger (AnFdc), which naturally catalyzes the reversible transformation of cinnamic acid to styrene and CO2. AnFdc displayed promising synthetic potentials and a broad compatibility of substrates, affording a series of deuterated aromatic heterocycles and styrene derivatives with high yields, site selectivity, and D incorporations.

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