Synthesis Of Fine Chemicals Research Articles

Structural Insights into Cold-Active Lipase from Glaciozyma antarctica PI12: Alphafold2 Prediction and Molecular Dynamics Simulation.

Cold-active enzymes have recently gained popularity because of their high activity at lower temperatures than their mesophilic and thermophilic counterparts, enabling them to withstand harsh reaction conditions and enhance industrial processes. Cold-active lipases are enzymes produced by psychrophiles that live and thrive in extremely cold conditions. Cold-active lipase applications are now growing in the detergency, synthesis of fine chemicals, food processing, bioremediation, and pharmaceutical industries. The cold adaptation mechanisms exhibited by these enzymes are yet to be fully understood. Using phylogenetic analysis, and advanced deep learning-based protein structure prediction tool Alphafold2, we identified an evolutionary processes in which a conserved cold-active-like motif is presence in a distinct subclade of the tree and further predicted and simulated the three-dimensional structure of a putative cold-active lipase with the cold active motif, Glalip03, from Glaciozyma antarctica PI12. Molecular dynamics at low temperatures have revealed global stability over a wide range of temperatures, flexibility, and the ability to cope with changes in water and solvent entropy. Therefore, the knowledge we uncover here will be crucial for future research into how these low-temperature-adapted enzymes maintain their overall flexibility and function at lower temperatures.

Sustainable synthesis of fine chemicals and polymers using industrial chlorine chemistry.

To achieve sustainable resource circulation, preparation of reactive species from stable compounds is unavoidable. Chlorine chemistry is an eco-friendly methodology to address this demand. Chlorine is industrially produced from sodium chloride (NaCl), an abundant natural resource in oceans. Chlorine provides various chemical products, including polymers, through chlorination and subsequent conversion reactions. In these reactions, the byproducts are usually hydrogen chloride, which is commercially utilized as hydrochloric acid and is finally neutralized to NaCl after use. Therefore, chlorine chemistry enables fine chemical production from NaCl with almost no wastage. This review provides an overview of the synthesis of fine chemicals and polymers using chlorine chemistry and discusses them from the perspective of sustainability.

Efficient selective hydrogenation of phenylacetylene over Pd-based rare earth dual-atomic catalysts

Selective hydrogenation of phenylacetylene to styrene plays a vital role in fine chemical synthesis with palladium (Pd)-based catalysts as the active components and usually suffered from low selectivity due to over-hydrogenation and low stability through polymerization (c.a. green oil generation). In this work, we found that by confining the Pd atom within a Pd-Ln (Ln: rare earth elements, such as Y, Lu, etc. ) diatomic structure [diatomic catalyst (DAC)], the reaction performance of selective hydrogenation of phenylacetylene has been greatly promoted, in which 92% styrene selectivity has been determined at 100% phenylacetylene conversion. This would be attributed to the diatomic structure established, which was achieved by introducing Pd-Ln precursors and confirmed by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray adsorption fine structure (XAFS) characterizations and it was demonstrated that slight electron transfer from Ln to the adjacent isolated Pd makes it slightly negatively charged and facilitated the styrene formation. Besides, a Langmuir-Hinshelwood model was established to describe the whole reaction mechanism. After a systematic kinetic investigation, it suggests that the C8H6* + H* elementary step is probably the kinetically relevant for the whole reaction and the surface of the catalyst is mainly covered by C8H6*. The energy relationship of each step along phenylacetylene hydrogenation was quantitatively described by means of parity fitting and gas isothermal adsorption, providing insights into the selective hydrogenation of phenylacetylene over 0.02%Pd-Ln/C (Ln = Y/Lu) catalysts and pave the way of catalytic design at the atomic level.

Selective oxidation of benzyl alcohols photocatalyzed by asymmetric cobalt thioporphyrazine supported on alumina

The sunlight-powered transformation of alcohols to corresponding carboxylic acids offers a feasible route for fine chemical synthesis. In this work, the asymmetric cobalt tri(2,3-bis(butylthio)maleonitrile)-(1,4-dithiin) porphyrazine (CoPz(SBu)6(dtn)) was synthesized, more importantly, its single crystal was further obtained by the solvent evaporation method. Then the asymmetric CoPz(SBu)6(dtn) supported on neutral Al2O3 particles to form composite photocatalyst CoPz(SBu)6(dtn)@Al2O3, which possessed strong visible light absorption. Under simulated sunlight irradiation using a xenon lamp, the composite photocatalyst CoPz(SBu)6(dtn)@Al2O3 exhibited excellent photocatalytic activity for selective oxidation of benzyl alcohol to benzoic acid in water under conditions of green H2O2 as oxidant and K2CO3 as additive. The conversion of benzyl alcohol was up to 53.8 % together with 99 % selectivity of benzoic acid over composite photocatalyst CoPz(SBu)6(dtn)@Al2O3. Meanwhile, this photocatalytic system had feasible substrate generalizability and excellent photocatalytic activity for substituted benzyl alcohols containing both electron-donating and electron-withdrawing substituents. The composite photocatalyst CoPz(SBu)6(dtn)@Al2O3 exhibited excellent photocatalytic durability, which was confirmed by the recycling experiments. This work manifests the asymmetric thioporphyrazine as photocatalyst is feasible in implementing sunlight-powered selective transformation.

In-situ ‘X’ doped ‘GCN’ photocatalyst enables selective aldehyde synthesis via photo-oxidation of benzyl alcohol under ambient conditions

Photo-oxidative selective conversion of benzyl alcohols using graphitic carbon nitride (GCN) is a sustainable strategy for conventional metal-doped heterogeneous catalytic oxidation systems. Non-metal doped graphitic carbon nitride (a subclass of GCN) enhances its properties as an efficient photocatalyst for oxidation. These heteroatom non-metal dopants alter the optical energy gap and chemical and electronic properties of GCN, making it ideal for creating cost-effective, practical utility. So, herein, we designed heteroatoms (X = B, S, C) doped GCN photocatalysts derived from melamine (M) with different heteroatom ingredients and compared their activity in detail. Among these, the photo-oxidation of benzyl alcohol under blue LED by S-doped GCN (S-GCN) photocatalyst exhibits utmost higher photocatalytic activity than other heteroatoms doped GCN photocatalyst due to suitable band gap and slow photoinduced charge carriers recombination. The suitable energy gap with higher chemical stability is accountable for the substantial increase in the photocatalytic efficiency of S-GCN in the solar light responsive integrating reactions of oxidation of benzyl alcohol in aerobic conditions. Attaining an exceptional >99 % selectivity towards benzaldehyde (up to 5 cycles without significant loss of activity) marks a remarkable milestone. This opens up new possibilities for using these simple non-metal-doped photocatalysts in fine chemical synthesis.

H2-driven biocatalysis for flavin-dependent ene-reduction in a continuous closed-loop flow system utilizing H2 from water electrolysis

Despite the increasing demand for efficient and sustainable chemical processes, the development of scalable systems using biocatalysis for fine chemical production remains a significant challenge. We have developed a scalable flow system using immobilized enzymes to facilitate flavin-dependent biocatalysis, targeting as a proof-of-concept asymmetric alkene reduction. The system integrates a flavin-dependent Old Yellow Enzyme (OYE) and a soluble hydrogenase to enable H2-driven regeneration of the OYE cofactor FMNH2. Molecular hydrogen was produced by water electrolysis using a proton exchange membrane (PEM) electrolyzer and introduced into the flow system via a designed gas membrane addition module at a high diffusion rate. The flow system shows remarkable stability and reusability, consistently achieving >99% conversion of ketoisophorone to levodione. It also demonstrates versatility and selectivity in reducing various cyclic enones and can be extended to further flavin-based biocatalytic approaches and gas-dependent reactions. This electro-driven continuous flow system, therefore, has significant potential for advancing sustainable processes in fine chemical synthesis.

Synthesis at the Interface of Chemistry and Biology.

ConspectusChemical synthesis as a tool to control the structure and properties of matter is at the heart of chemistry─from the synthesis of fine chemicals and polymers to drugs and solid-state materials. But as the field evolves to tackle larger and larger molecules and molecular complexes, the traditional tools of synthetic chemistry become limiting. In contrast, Mother Nature has developed very different strategies to create the macromolecules and molecular systems that make up the living cell. Our focus has been to ask whether we can use the synthetic strategies and machinery of Mother Nature, together with modern chemical tools, to create new macromolecules, and even whole organisms with properties not existing in nature. One such example involves reprogramming the complex, multicomponent machinery of ribosomal protein synthesis to add new building blocks to the genetic code, overcoming a billion-year constraint on the chemical nature of proteins. This methodology exploits the concept of bioorthogonality to add unique codons, tRNAs and aminoacyl-tRNA synthetases to cells to encode amino acids with physical, chemical and biological properties not found in nature. As a result, we can make precise changes to the structures of proteins, much like those made by chemists to small molecules and beyond those possible by biological approaches alone. This technology has made it possible to probe protein structure and function in vitro and in vivo in ways heretofore not possible, and to make therapeutic proteins with enhanced pharmacology. A second example involves exploiting the molecular diversity of the humoral immune system together with synthetic transition state analogues to make catalytic antibodies, and then expanding this diversity-based strategy (new to chemists at the time) to drug discovery and materials science. This work ushered in a new nature-inspired synthetic strategy in which large libraries of natural or synthetic molecules are designed and then rationally selected or screened for new function, increasing the efficiency by which we can explore chemical space for new physical, chemical and biological properties. A final example is the use of large chemical libraries, robotics and high throughput phenotypic cellular screens to identify small synthetic molecules that can be used to probe and manipulate the complex biology of the cell, exemplified by druglike molecules that control cell fate. This approach provides new insights into complex biology that complements genomic approaches and can lead to new drugs that act by novel mechanisms of action, for example to selectively regenerate tissues. These and other advances have been made possible by using our knowledge of molecular structure and reactivity hand in hand with our understanding of and ability to manipulate the complex machinery of living cells, opening a new frontier in synthesis. This Account overviews the work in my lab and with our collaborators, from our early days to the present, that revolves around this central theme.

Synthesis of N-heterocycles through alcohol dehydrogenative coupling.

Nitrogen heterocycles are found in the structures of many biologically important compounds, as well as materials used in the synthesis of fine chemicals. Notably, ~59% of US Food and Drug Administration-approved small-molecule drugs contain nitrogen heterocycles. It is therefore meaningful to explore greener or more sustainable methods for their synthesis. The use of alcohols as reagents is attractive as they can be readily obtained from biomass derived natural resources. In the last two decades, alcohol dehydrogenative coupling reaction to synthesize various heterocycles were extensively explored which furnished hydrogen (H2) and water (H2O) as the two greener byproducts. In this protocol, we describe several efficient catalytic transformations to synthesize quinolines, 1,8-naphthyridines, quinoxalines, quinazolines, pyrimidines, benzimidazoles, pyrroles and pyridines, using alcohol as starting materials. We also describe the synthesis of several homogeneous iridium/ruthenium catalysts and heterogeneous cobalt/copper catalysts that can be used in these transformations. The reaction setup is simple; in a Schlenk/reaction tube with magnetic stir-bar, alcohol, corresponding coupling reagents (nucleophiles), catalyst, base and solvent (water or organic solvent such as toluene, dioxane or p-xylene) are added. The reaction mixture is refluxed at the specified temperature (110-150 °C)-either in air or under argon-to furnish these heterocycles. Synthesis of the catalysts takes 3-5 h and the coupling reactions take 4-5 h depending on the target product. The cobalt- and copper-based heterogeneous catalytic systems displayed an good catalyst recyclability.

Photocorrosion suppression of copper sulfide via hybridization with amino-functionalized metal–organic framework for natural sunlight-driven photocatalysis

Natural sunlight-driven photocatalysis has been considered as an energy sustainable strategy for the synthesis of fine chemicals, since natural sunlight is inexhaustible. Copper sulfide (CuS) with broad light absorption holds great promise for natural sunlight utilization, while hole-induced photocorrosion seriously hampers its photoactivity and photostability. Herein, we inhibited the photocorrosion by hybridizing CuS with amino-functionalized metal–organic framework of NH2-MIL-125(Ti) (NM125) to fabricate a Z-scheme heterojunction. Taking advantage of high binding affinity of amino group and copper ion, CuS nanoparticles (NPs) were in situ anchored on NM125 surface via amino group-assisted coordination. Characterization results suggested the diffusion-controlled charge migration in NM125@CuS(x) hybrids, where photoinduced electrons in conduction band (CB) of NM125 transferred to valence band (VB) of CuS, and then combined here. The Z-scheme charge transport could timely consume the photogenerated holes of CuS, and spatially separated the charge carriers. As a result, the obtained NM125@CuS(x) catalysts were highly efficient and stable in natural sunlight-driven Phillips-Ladenburg reaction in air, providing serial benzimidazoles with excellent yields (90–98%). Such natural sunlight-driven photocatalysis system efficiently utilized natural sunlight to synthesize high-value fine chemicals in open air at mild conditions, which opens up a sustainable avenue for the green development of fine chemical engineering.

Ni(II)‐Complex Anchored Over Functionalized Mesoporous SBA‐15: A Nanocatalyst for the Synthesis of Aminophenoxazinone Derivatives

AbstractImmobilization of the reactive metal sites over high surface area porous nanomaterial is a very demanding route in designing novel nanocatalysts for the synthesis of valuable fine chemicals. Here we report an efficient, eco‐friendly and sustainable route for the synthesis of aminophenoxazinone derivatives via oxidative coupling of o‐aminophenols catalysed by a novel mesoporous highly ordered Ni(II)‐complex functionalized mesoporous heterogeneous organosilica catalyst. A novel structurally characterized Ni(II)‐complex derived from 2‐(I‐(2‐(piperizin‐1‐yl) ethylimino) methyl)‐5‐methylphenol ligand has been immobilised over a 2D‐hexagonally ordered functionalized mesoporous SBA‐15 synthesized via surface functionalization of SBA‐15 material with 3‐aminopropyltriethoxysilane (APTES) to obtain the Ni(II)‐nanocatalyst SANI. Its catalytic activity has been explored for three different substrates like o‐aminophenol (OAP), 3‐amino‐4‐hydroxybenzoic acid (CAP) and 2‐amino‐4‐methylphenol (MAP) that produces corresponding phenoxazinone derivatives having the yields of 92, 81 and 85 %, respectively. suggesting wide scope of this supported mesoporous nanocatalyst.

Enantioselective Allylboration of Acetylene: A Versatile Tool for the Stereodivergent Synthesis of Natural Products.

Efficient catalytic methods that allow the use of simple and abundant chemical feedstocks for the preparation of synthetically versatile compounds are central to modern synthetic chemistry. Acetylene is a basic feedstock with a remarkable production over one million tons per year, although it is underutilized in the stereoselective synthesis of fine chemicals. Here we report a facile catalytic multicomponent reaction that allows for the enantio- and diastereoselective allylboration of acetylene gas. This process is catalyzed by a chiral copper catalyst, operates without specialized equipment or pressurization, and provides chiral skipped dienes bearing stereodefined and orthogonally functionalized olefins with excellent levels of chemo-, regio-, enantio- and diastereoselectivity. The combined stereochemical features and orthogonal functionalization make the products privileged structural scaffolds to access the complete set of stereoisomers of the chiral skipped diene core through simple enantio- and diastereodivergent pathways. The utility of the method is demonstrated with the enantioselective synthesis of three bioactive natural skipped diene products, namely (+)-Nyasol, (+)-Hinokiresinol and Phorbasin C, and other related synthetically relevant chiral molecules.

Enantioselective Allylboration of Acetylene: A Versatile Tool for the Stereodivergent Synthesis of Natural Products

AbstractEfficient catalytic methods that allow the use of simple and abundant chemical feedstocks for the preparation of synthetically versatile compounds are central to modern synthetic chemistry. Acetylene is a basic feedstock with a remarkable production over one million tons per year, although it is underutilized in the stereoselective synthesis of fine chemicals. Here we report a facile catalytic multicomponent reaction that allows for the enantio‐ and diastereoselective allylboration of acetylene gas. This process is catalyzed by a chiral copper catalyst, operates without specialized equipment or pressurization, and provides chiral skipped dienes bearing stereodefined and orthogonally functionalized olefins with excellent levels of chemo‐, regio‐, enantio‐ and diastereoselectivity. The combined stereochemical features and orthogonal functionalization make the products privileged structural scaffolds to access the complete set of stereoisomers of the chiral skipped diene core through simple enantio‐ and diastereodivergent pathways. The utility of the method is demonstrated with the enantioselective synthesis of three bioactive natural skipped diene products, namely (+)‐Nyasol, (+)‐Hinokiresinol and Phorbasin C, and other related synthetically relevant chiral molecules.

Ni2MnAl Heusler Alloy Nanoparticles for Chemoselective Hydrogenation of Nitro Compounds

AbstractDespite immense interest for years in Heusler alloys as magnetoelastic materials, their application in heterogeneous catalysis has only recently been explored. We report the development of highly active, robust and magnetically separable Ni2MnAl Heusler alloy nanoparticles as a heterogeneous catalyst for hydrogenation of aliphatic and aromatic nitro compounds to the corresponding amines. The easily synthesizable Ni2MnAl nanoparticles are thermally and chemically robust and exhibited excellent chemoselectivity in the hydrogenation of a range of aliphatic and aromatic nitroarenes, including those bearing functional groups sensitive to reduction, such as alkene, bromo, iodo, carbonyl and cyano, yielding the respective functionalized amines in good yields. Moreover, this solid catalyst is magnetically separable from the reaction mixture and could be recycled and reused at least 10 times without any loss in catalytic activity. The mechanism of the Ni2MnAl Heusler alloy nanoparticles catalyzed nitro reduction was studied by various spectroscopy, control experiments and kinetics. Our work opens a new avenue of developing heterogeneous earth‐abundant metal catalysis for economic and environment‐friendly synthesis of fine chemicals owing to straightforward synthesis and tunable composition of Heusler alloy nanoparticles from base‐metal precursors and their diverse structure and properties in conjunction with their thermal and chemical stability, excellent chemoselectivity, magnetic separability and recyclability.

Highly Active and Selective Fe‐MOF/2D‐Montmorillonite Photocatalyst via in‐situ Preparation for Hydroxylation of Benzene to Phenol

AbstractThe photocatalytic hydroxylation of benzene to phenol is an important reaction for the synthesis of fine chemicals and pharmaceuticals. However, the development of efficient and selective photocatalysts for this reaction remains a challenge. Here, a highly active and selective Fe‐MOF/2D‐montmorillonite (Fe‐MOF/MMT) photocatalyst was prepared via an in‐situ method for the hydroxylation of benzene to phenol under the visible light irradiation. The Fe‐MOF/MMT composite exhibited excellent photocatalytic performance, with phenol yield of 30.3 % and benzene selectivity of 96.5 % within 4 hours. The high activity and selectivity of the Fe‐MOF/MMT photocatalyst were attributed to the synergistic effect between the Fe‐MOF and MMT, as well as the unique 2D structure of MMT, which facilitated charge separation and transfer. The Fe‐MOF/MMT composite also showed good stability and re‐used without significant decrease of activity. This study demonstrated that the potential of Fe‐MOF/MMT as a highly efficient and selective photocatalyst for the hydroxylation of benzene to phenol and provided an insight into the design of advanced photocatalysts for sustainable chemical synthesis.

Acid-base synergistic effect towards catalytic transfer hydrogenation reactions

Catalytic transfer hydrogenation (CTH) of aldehydes/ketones by using alcohols as hydrogen donors is an attractive and environmentally friendly hydrogenation technology, which has evoked widespread attention in synthesis of fine chemicals from biomass resources. In this work, a Co-Al mixed metal oxide catalyst (Co1Al2-MMO-200) was obtained through structural topological transformation process of layered double hydroxides, which was used in the CTH reaction of furfural with isopropanol. Notably, the reaction rate achieves 0.023 mol g−1 h−1, which is preponderate to acid-base catalysts earlier reported. The joint research based on CO2-TPD, NH3-TPD and poisoning experiment substantiates that the synergy effect of acid-base sites plays an essential role in this catalytic system. Isotopic labelling MS, in-situ FT-IR and DFT studies further verify that the CTH reaction of furfural occurs via the Meerwein-Ponndorf-Verley (MPV) route, in which the basic site promotes the deprotonation of isopropanol whilst the acid site facilitates the formation of a six-membered ring transition state. This work demonstrates an acid-base synergetic catalysis for the CTH reaction by revealing the structure-property correlation and exploring reaction route, which is instructive for designing high-performance heterogenous catalysts.

Mechanochemical Synthesis of α-halo Alkylboronic Esters.

α-halo alkylboronic esters, acting as ambiphilic synthons, play a pivotal role as versatile intermediates in fields like pharmaceutical science and organic chemistry. The sequential transformation of carbon-boron and carbon-halogen bonds into a broad range of carbon-X bonds allows for programmable bond formation, facilitating the incorporation of multiple substituents at a single position and streamlining the synthesis of complex molecules. Nevertheless, the synthetic potential of these compounds is constrained by limited reaction patterns. Additionally, the conventional methods often necessitate the use of bulk toxic solvents, exhibit sensitivity to air/moisture, rely on expensive metal catalysts, and involve extended reaction times. In this report, a ball milling technique is introduced that overcomes these limitations, enabling the external catalyst-free multicomponent coupling of aryl diazonium salts, alkenes, and simple metal halides. This approach offers a general and straightforward method for obtaining a diverse array of α-halo alkylboronic esters, thereby paving the way for the extensive utilization of these synthons in the synthesis of fine chemicals.

Constructing Ni-Pt Bimetallic Catalysts for Catalytic Hydrogenation and Rearrangement of Furfural into Cyclopentanone with Insight in H/D Exchange by D2O Labeling.

Developing a metallic catalyst for converting furfural (FAL) to highly valuable products such as cyclopentanone (CPO) is important for fine chemical synthesis by the efficient utilization of biomass resources. The presence of diverse unsaturated carbon atoms in FAL and the rearrangement of oxygen atoms hinder the production of CPO. We developed an optimal nickel (Ni)-to-platinum (Pt) molar ratio (1:0.007) for a bimetallic Ni-Pt/alumina (Al2O3) catalyst with a low Pt loading via an impregnation method to efficiently catalyze the selective hydrogenation of FAL in an aqueous solution to form CPO. The comprehensive characterizations by X-ray diffraction and X-ray absorption near edge structure analyses elucidated the formation of Ni0/Pt0 and Ni2+/Pt4+ after reduction by H2. The addition of a low amount of the Pt-Ni/Al2O3 catalyst resulted in an alleviation of H2 reduction behavior detected by hydrogen temperature-programmed reduction, accompanied by low H2 desorption ability observed by hydrogen temperature-programmed desorption. The catalytic activity of Ni-Pt/Al2O3 was higher than those of Ni/Al2O3 and Pt/Al2O3 catalysts. The maximum CPO yield was 66% with 93% FAL conversion under the optimized conditions (160 °C, 20 bar of H2 pressure, and 2 h). Isotopic deuterium oxide (D2O) labeling revealed the transfer of deuterium (D) atoms from D2O to the intermediates and products during hydrogenation and rearrangement, which confirmed that water was a medium for rearrangement and the source of hydrogen for the reaction. This study developed an efficient catalyst for the catalytic hydrogenation and ring rearrangement of FAL into CPO.

Synthesis of Versatile Aryliodine Synthons by Aryliodonium Rearrangement Reactions

AbstractThe excellent reactivity of diaryliodonium salts has primarily been attributed to the efficient departure of the iodoarene unit, facilitating a variety of arylation reactions. However, one equivalent of iodoarene as a side‐product is a chemical waste in these reactions, which was criticized by chemists for hindering its popularity. Recently, the development of synthetic methodology that preserve the aryl iodine moiety received increasing attention. Oxidative rearrangement reactions involving aryliodonium reagents have significantly addressed the atom‐economic issue, thereby broadening the reaction scope. The resulting intricate aryliodine products are viewed as valuable synthons for the synthesis of natural products, pharmaceutical intermediates and other fine chemicals.

Mechanism-Guided Computational Design Drives meso-Diaminopimelate Dehydrogenase to Efficient Synthesis of Aromatic d-amino Acids.

Aromatic d-amino acids (d-AAs) play a pivotal role as important chiral building blocks and key intermediates in fine chemical and drug synthesis. Meso-diaminopimelate dehydrogenase (DAPDH) serves as an excellent biocatalyst in the synthesis of d-AAs and their derivatives. However, its strict substrate specificity and the lack of efficient engineering methods have hindered its widespread application. Therefore, this study aims to elucidate the catalytic mechanism underlying DAPDH from Proteus vulgaris (PvDAPDH) through the examination of its crystallographic structure, computational simulations of potential energies and molecular dynamics simulations, and site-directed mutagenesis. Mechanism-guided computational design showed that the optimal mutant PvDAPDH-M3 increased specific activity and catalytic efficiency (kcat/Km) for aromatic keto acids up to 124-fold and 92.4-fold, respectively, compared to that of the wild type. Additionally, it expanded the substrate scope to 10 aromatic keto acid substrates. Finally, six high-value-added aromatic d-AAs and their derivatives were synthesized using a one-pot three-enzyme cascade reaction, exhibiting a good conversion rate ranging from 32 to 84% and excellent stereoselectivity (enantiomeric excess >99%). These findings provide a potential synthetic pathway for the green industrial production of aromatic d-AAs.

Dawn of a new era? A base-metal single-atom catalyst for organic fine chemical synthesis

Dawn of a new era? A base-metal single-atom catalyst for organic fine chemical synthesis