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The development of efficient and sustainable methods for the synthesis of nitrogen heterocycles is an important goal for the chemical industry. In particular, substituted chiral piperidines are prominent targets due to their prevalence in medicinally relevant compounds and their precursors. A potential biocatalytic approach to the synthesis of this privileged scaffold would be the asymmetric dearomatization of readily assembled activated pyridines. However, nature is yet to yield a suitable biocatalyst specifically for this reaction. Here, by combining chemical synthesis and biocatalysis, we present a general chemo-enzymatic approach for the asymmetric dearomatization of activated pyridines for the preparation of substituted piperidines with precise stereochemistry. The key step involves a stereoselective one-pot amine oxidase/ene imine reductase cascade to convert N-substituted tetrahydropyridines to stereo-defined 3- and 3,4-substituted piperidines. This chemo-enzymatic approach has proved useful for key transformations in the syntheses of antipsychotic drugs Preclamol and OSU-6162, as well as for the preparation of two important intermediates in synthetic routes of the ovarian cancer monotherapeutic Niraparib.

The case for a renewed focus on Nature in drug discovery is reviewed; not in terms of natural product screening, but how and why biomimetic molecules, especially those produced by natural processes, should deliver in the age of artificial intelligence and screening of vast collections both in vitro and in silico. The declining natural product-likeness of licensed drugs and the consequent physicochemical implications of this trend in the context of current practices are noted. To arrest these trends, the logic of seeking new bioactive agents with enhanced natural mimicry is considered; notably that molecules constructed by proteins (enzymes) are more likely to interact with other proteins (e.g., targets and transporters), a notion validated by natural products. Nature's finite number of building blocks and their interactions necessarily reduce potential numbers of structures, yet these enable expansion of chemical space with their inherent diversity of physical characteristics, pertinent to property-based design. The feasible variations on natural motifs are considered and expanded to encompass pseudo-natural products, leading to the further logical step of harnessing bioprocessing routes to access them. Together, these offer opportunities for enhancing natural mimicry, thereby bringing innovation to drug synthesis exploiting the characteristics of natural recognition processes. The potential for computational guidance to help identifying binding commonalities in the route map is a logical opportunity to enable the design of tailored molecules, with a focus on "organic/biological" rather than purely "synthetic" structures. The design and synthesis of prototype structures should pay dividends in the disposition and efficacy of the molecules, while inherently enabling greener and more sustainable manufacturing techniques.

Amino-polyols represent attractive chemical building blocks but can be challenging to synthesize because of the high density of asymmetric functionalities and the need for extensive protecting-group strategies. Here we present a three-component strategy for the stereoselective enzymatic synthesis of amino-diols and amino-polyols using a diverse set of prochiral aldehydes, hydroxy ketones, and amines as starting materials. We were able to combine biocatalytic aldol reactions, using variants of d-fructose-6-phosphate aldolase (FSA), with reductive aminations catalyzed by IRED-259, identified from a metagenomic library. A two-step process, without the need for intermediate isolation, was developed to avoid cross-reactivity of the carbonyl components. Stereoselective formation of the 2R,3R,4R enantiomers of amino-polyols was observed and confirmed by X-ray crystallography., We kindly acknowledge financial support from the European Research Council (788231-ProgrES-ERC-2017-ADG to S.L.F.; BIO-H-BORROW to N.J.T.). J.R.M. acknowledges the Industrial Biotechnology Innovation Centre (IBioIC) and BBSRC funding through a CASE studentship with Prozomix Ltd. P.C. acknowledges financial support from the project RTI2018-094637-BI00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe” and project PCI2018-092937 MCIN/AEI/10.13039/501100011033 cofunded by the UE under the ERACoBioTech Tralaminol (European Union’s Horizon 2020 research and innovation programme grant agreement no. 722361).

The unique ability of the 'electrochemical leaf' (e-Leaf) to drive and control nanoconfined enzyme cascades bidirectionally, while directly monitoring their rate in real-time as electrical current, is exploited to achieve deracemisation and stereoinversion of secondary alcohols using a single electrode in one pot. Two alcohol dehydrogenase enzymes with opposing enantioselectivities, from

In 2017, two companies, Novartis AG and Syngenta AG, joined forces with the group of Prof. Buller, head of the Competence Center for Biocatalysis (CCBIO), to tackle the challenge of enzymatic late-stage halogenation. This biocatalytic method was considered to provide a more sustainable approach to late-stage halogenation of complex molecules than traditional synthetic approaches. Using machine-learning guided protein engineering, α-ketoglutarate dependent halogenases were evolved into versatile catalysts capable of selectively chlorinating inactivated C−H bonds. Structurally diverse molecules, namely an analogue of martinelline as well as two members of the soraphen natural product family, were enzymatically chlorinated at two distinct positions in a regio- and stereoselective manner, thus demonstrating the synthetic usefulness of such a strategy. As part of our three-year collaboration, flavin-dependent halogenases were also studied.

2-Aminotetralin and 3-aminochroman derivatives are key structural motifs present in a wide range of pharmaceutically important molecules. Herein, we report an effective biocatalytic approach towards these molecules through the enantioselective reductive coupling of 2-tetralones and 3-chromanones with a diverse range of primary amine partners. Metagenomic imine reductases (IREDs) were employed as the biocatalysts, obtaining high yields and enantiocomplementary selectivity for >15 examples at preparative scale, including the precursors to Ebalzotan, Robalzotan, Alnespirone and 5-OH-DPAT. We also present a convergent chemo-enzymatic total synthesis of the Parkinson's disease therapy Rotigotine in 63 % overall yield and 92 % ee.

The importance of energized nanoconfinement for facilitating the study and execution of enzyme cascades that feature multiple exchangeable cofactors is demonstrated by experiments with carboxylic acid reductase (CAR), an enzyme that requires both NADPH and ATP during a single catalytic cycle. Conversion of cinnamic acid to cinnamaldehyde by a package of four enzymes loaded into and trapped in the random nanopores of an indium tin oxide (ITO) electrode is driven and monitored through the simultaneous delivery of electrical and chemical energy. The electrical energy is transduced by ferredoxin NADP+ reductase, which undergoes rapid, direct electron exchange with ITO and regenerates NADP(H). The chemical energy provided by phosphoenolpyruvate, a fuel contained in the bulk solution, is cotransduced by adenylate kinase and pyruvate kinase, which efficiently convert the AMP product back into ATP that is required for the next cycle. The use of the two-kinase system allows the recycling process to be dissected to evaluate the separate roles of AMP removal and ATP supply during presteady-state and steady-state catalysis.

A key aim of biocatalysis is to mimic the ability of eukaryotic cells to carry out multistep cascades in a controlled and selective way. As biocatalytic cascades get more complex, reactions become unattainable under typical batch conditions. Here a number of continuous flow systems were used to overcome batch incompatibility, thus allowing for successful biocatalytic cascades. As proof‐of‐principle, reactive carbonyl intermediates were generated in situ using alcohol oxidases, then passed directly to a series of packed‐bed modules containing different aminating biocatalysts which accordingly produced a range of structurally distinct amines. The method was expanded to employ a batch incompatible sequential amination cascade via an oxidase/transaminase/imine reductase sequence, introducing different amine reagents at each step without cross‐reactivity. The combined approaches allowed for the biocatalytic synthesis of the natural product 4O‐methylnorbelladine., The use of continuous flow reactors enabled previously inaccessible enzyme combinations in multi‐enzyme cascade reactions. This included the combination of oxidases with aminating biocatalysts (transaminase/reductive aminase) and was extended to the continuous in situ biocatalytic generation of amino donors for the reductive aminase.

Allylic amines are a versatile class of synthetic precursors of many valuable nitrogen-containing organic compounds, including pharmaceuticals. Enzymatic allylic amination methods provide a sustainable route to these compounds but are often restricted to allylic primary amines. We report a biocatalytic system for the reductive N-allylation of primary and secondary amines, using biomass-derivable cinnamic acids. The two-step one-pot system comprises an initial carboxylate reduction step catalyzed by a carboxylic acid reductase to generate the corresponding α,β-unsaturated aldehyde in situ. This is followed by reductive amination of the aldehyde catalyzed by a bacterial reductive aminase pIR23 or BacRedAm to yield the corresponding allylic amine. We exploited pIR23, a prototype bacterial reductive aminase, self-sufficient in catalyzing formal reductive amination of α,β-unsaturated aldehydes with various amines, generating a broad range of secondary and tertiary amines accessed in up to 94% conversion under mild reaction conditions. Analysis of products isolated from preparative reactions demonstrated that only selective hydrogenation of the C=N bond had occurred, preserving the adjacent alkene moiety. This process represents an environmentally benign and sustainable approach for the synthesis of secondary and tertiary allylic amine frameworks, using renewable allylating reagents and avoiding harsh reaction conditions. The selectivity of the system ensures that bis-allylation of the alkylamines and (over)reduction of the alkene moiety are avoided.

We report a new synthesis of the Covid-19 drug nirmatrelvir featuring a highly enantioselective biocatalytic desymmetrization and a diastereoselective multicomponent reaction as the key steps. Our route avoids the use of transition metals and peptide coupling reagents, resulting in an overall highly atom-economic process.

The development of cost-effective and green enzyme immobilisation techniques will facilitate the adoption of continuous flow biocatalysis (CFB) by industry and academia. In this work, a relatively mild sulfite pulping process was employed to remove lignin and hemicellulose from wood with minimal disruption of its native porous structure, resulting in aligned macroporous cellulosic monoliths termed cellulose scaffolds (CSs). By engineering carbohydrate-binding modules (CBMs) onto the termini of recombinant proteins, the CSs could be employed as low-cost, renewable and biodegradable materials for enzyme immobilisation without any further chemical functionalisation. CBM-tagged fluorescent proteins were initially employed to demonstrate proof-of-principle and to optimise immobilisation conditions; this resulted in initial protein loadings as high as 5.24 wt% and immobilisation efficiencies as high as 97.1%. The process was then translated to a CBM-tagged ω-transaminase (ωTA) from Bacillus megaterium, obtaining enzyme loadings and immobilisation efficiencies as high as 3.99 wt% and 82.4%, respectively. A demonstrative CFB reaction with the immobilised CBM-tagged ωTA displayed ca. 95 ± 5% conversion efficiency relative to the free enzyme in solution under analogous conditions, suggesting that CBM-tagged recombinant enzymes immobilised on wood-derived CSs could potentially compete with other, more complex and costly enzyme immobilisation technologies.

N-alkanoyl-N-methylglucamides (MEGAs) are non-toxic surfactants widely used as commercial ingredients, but more sustainable syntheses towards these compounds are highly desirable. Here, we present a biocatalytic route towards MEGAs and analogues using a truncated carboxylic acid reductase construct tailored for amide bond formation (CARmm-A). CARmm-A is capable of selective amide bond formation without the competing esterification reaction observed in lipase catalysed reactions. A kinase was implemented to regenerate ATP from polyphosphate and by thorough reaction optimisation using design of experiments, the amine concentration needed for amidation was significantly reduced. The wide substrate scope of CARmm-A was exemplified by the synthesis of 24 commercially relevant amides, including selected examples on a preparative scale. This work establishes acyl-phosphate mediated chemistry as a highly selective strategy for biocatalytic amide bond formation in the presence of multiple competing alcohol functionalities.

The direct asymmetric reductive amination of heteroaryl ketones has been a long-standing synthetic challenge. Here we report the engineering of an amine dehydrogenase (AmDH) from Jeotgalicoccus aerolatus for the asymmetric synthesis of chiral α-(hetero)aryl primary amines in excellent conversions (up to 99 %) and enantioselectivities (up to 99 % ee). The best AmDH variant (Ja-AmDH-M3

Allylic amines are a versatile class of synthetic precursors of many valuable nitrogen-containing organic compounds, including pharmaceuticals. Enzymatic allylic amination methods provide a sustainable route to these compounds but are often restricted to allylic primary amines. We report a biocatalytic system for the reductive

The enantioselective oxidation of 2° alcohols to ketones is an important reaction in synthetic chemistry, especially if it can be achieved using O

Covering: 2015 up to July 2021The market for cosmetics is consumer driven and the desire for green, sustainable and natural ingredients is increasing. The use of isolated enzymes and whole-cell organisms to synthesise these products is congruent with these values, especially when combined with the use of renewable, recyclable or waste feedstocks. The literature of biocatalysis for the synthesis of ingredients in cosmetics in the past five years is herein reviewed.

Monoacylated diamines are common motifs present in pharmaceuticals, agrochemicals, and natural products. However, the synthesis of these compounds often requires selective protection/deprotection s...

Formate dehydrogenases (FDHs) are NAD(P)H-dependent enzymes that catalyse the reversible oxidation of formate to CO2. The main goal was to use directed evolution to obtain variants of the FDH from Chaetomium thermophilum (CtFDH) with enhanced reduction activity in the conversion of CO2 into formic acid. Four libraries were constructed targeting five residues in the active site. We identified two variants (G93H/I94Y and R259C) with enhanced reduction activity which were characterised in the presence of both aqueous CO2(g) and HCO3−. The A1 variant (G93H/I94Y) showed a 5.4-fold increase in catalytic efficiency (kcat/KM) compared to that of the wild-type for HCO3− reduction. The improved biocatalysts were also applied as a coupled cofactor recycling system in the enantioselective oxidation of 4-phenyl-2-propanol catalysed by the alcohol dehydrogenase from Streptomyces coelicolor A3 (ScADH). Conversions in these reactions increased from 56 to 91% when the A1 variant was used instead of wild-type CtFDH. Two variants presenting up to five-fold increase in catalytic efficiency and kcat were obtained and characterised. They constitute a promising enzymatic alternative for CO2 utilization and will serve as scaffolds to be further developed in order to meet industrial requirements.

Sustainable production of fine chemicals and biofuels from renewable biomass offers a potential alternative to the continued use of finite geological oil reserves. However, in order to compete with current petrochemical refinery processes, alternative biorefinery processes must overcome significant costs and productivity barriers. Herein, we demonstrate the biocatalytic production of the versatile chemical building block, coniferol, for the first time, directly from lignocellulosic biomass. Following the biocatalytic treatment of lignocellulose to release and convert ferulic acid with feruloyl esterase (XynZ), carboxylic acid reductase (CAR) and aldo-keto reductase (AKR), this whole cell catalytic cascade not only achieved equivalent release of ferulic acid from lignocellulose compared to alkaline hydrolysis, but also displayed efficient conversion of ferulic acid to coniferol. This system represents a consolidated biodegradation–biotransformation strategy for the production of high value fine chemicals from waste plant biomass, offering the potential to minimize environmental waste and add value to agro-industrial residues.\ud \ud

Multi-enzyme cascades utilising variants of galactose oxidase and imine reductase led to the successful conversion of N-Cbz-protected l-ornithinol and l-lysinol to l-3-N-Cbz-aminopiperidine and l-3-N-Cbz-aminoazepane respectively, in up to 54% isolated yield. Streamlining the reactions into one-pot prevented potential racemisation of key labile intermediates and led to products with high enantiopurity.

Bio-based production of industrial chemicals using synthetic biology can provide alternative green routes from renewable resources, allowing for cleaner production processes. To efficiently produce chemicals on-demand through microbial strain engineering, biomanufacturing foundries have developed automated pipelines that are largely compound agnostic in their time to delivery. Here we benchmark the capabilities of a biomanufacturing pipeline to enable rapid prototyping of microbial cell factories for the production of chemically diverse industrially relevant material building blocks. Over 85 days the pipeline was able to produce 17 potential material monomers and key intermediates by combining 160 genetic parts into 115 unique biosynthetic pathways. To explore the scale-up potential of our prototype production strains, we optimized the enantioselective production of mandelic acid and hydroxymandelic acid, achieving gram-scale production in fed-batch fermenters. The high success rate in the rapid design and prototyping of microbially-produced material building blocks reveals the potential role of biofoundries in leading the transition to sustainable materials production., Graphical abstract Image 1, Highlights • An automated biomanufacturing pipeline is benchmarked for the production of material monomers. • Over 85 days, 160 genes were screened for activity, assembled into 115 unique pathways and tested for in vivo production. • E. coli production strains were successfully constructed to produce 17 target compounds at competitive titers. • Scale-up potential is demonstrated through enantioselective production of mandelic acid targets at gram-scale in bioreactors. • The high success rate demonstrates the capabilities of biofoundries to rapidly prototype microbial production strains.

Organic chemistry provides society with fundamental products we use daily. Concerns about the impact that the chemical industry has over the environment is propelling major changes in the way we manufacture chemicals. Biocatalysis offers an alternative to other synthetic approaches as it employs enzymes, Nature's catalysts, to carry out chemical transformations. Enzymes are biodegradable, come from renewable sources, operate under mild reaction conditions, and display high selectivities in the processes they catalyse. As a highly multidisciplinary field, biocatalysis benefits from advances in different areas, and developments in the fields of molecular biology, bioinformatics, and chemical engineering have accelerated the extension of the range of available transformations (E. L. Bell et al., Nat. Rev. Meth. Prim. 2021, 1, 1–21). Recently, we surveyed advances in the expansion of the scope of biocatalysis via enzyme discovery and protein engineering (J. R. Marshall et al., Tetrahedron 2021, 82, 131926). Herein, we focus on novel enzymes currently available to the broad synthetic community for the construction of new C−C, C−N and C−O bonds, with the purpose of providing the non-specialist with new and alternative tools for chiral and sustainable chemical synthesis., We would like to thank the Industrial Biotechnology Innovation Centre (IBioIC) and Biotechnology and Biological Sciences Research Council (BBSRC) for the awarding the CASE studentship to J.R.M. from Prozomix Ltd. J.J.S. is grateful to the Industrial Affiliates of CoEBio3 for a PhD studentship. N.J.T. is grateful to the ERC for the award of an Advanced Grant (Grant number 742987). J.M.-S. thanks the ARAID Foundation for personal funding and the Research Group E07_20R for scientific support. He also thanks the Agencia Estatal de Investigación for financial support (PID2020-113351RA-100/AEI/10.13039/501100011033).