scholarly journals Altering the Stereoselectivity of Whole-Cell Biotransformations via the Physicochemical Parameters Impacting the Processes

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 781
Author(s):  
Agnieszka Raczyńska ◽  
Joanna Jadczyk ◽  
Małgorzata Brzezińska-Rodak
Keyword(s):  
Culture Conditions ◽  
Biologically Active ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
Chiral Compounds ◽  
Physicochemical Factors ◽  
Pure Compounds ◽  
Genetic Level ◽  
Prochiral Ketones ◽  
Optically Pure

The enantioselective synthesis of organic compounds is one of the great challenges in organic synthetic chemistry due to its importance for the acquisition of biologically active derivatives, e.g., pharmaceuticals, agrochemicals, and others. This is why biological systems are increasingly applied as tools for chiral compounds synthesis or modification. The use of whole cells of “wild-type” microorganisms is one possible approach, especially as some methods allow improving the conversion degrees and controlling the stereoselectivity of the reaction without the need to introduce changes at the genetic level. Simple manipulation of the culture conditions, the form of a biocatalyst, or the appropriate composition of the biotransformation medium makes it possible to obtain optically pure products in a cheap, safe, and environmentally friendly manner. This review contains selected examples of the influence of physicochemical factors on the stereochemistry of the biocatalytic preparation of enantiomerically pure compounds, which is undertaken through kinetically controlled separation of their racemic mixtures or reduction of prochiral ketones and has an effect on the final enantiomeric purity and enantioselectivity of the reaction.

scholarly journals Current applications of kinetic resolution in the asymmetric synthesis of substituted pyrrolidines

2021 ◽  
Author(s):  
Sian Stephanie Berry ◽  
Simon Jones
Keyword(s):  
Asymmetric Synthesis ◽  
Traditional Method ◽  
Kinetic Resolution ◽  
Biologically Active ◽  
Enantiomerically Pure ◽  
Pure Compounds

Chiral substituted pyrrolidines are key elements in various biologically active molecules and are therefore valuable synthetic targets. One traditional method to enantiomerically pure compounds is the application of kinetic resolution....

Recent Advances in Catalytic Nonenzymatic Kinetic Resolution of Tertiary Alcohols

Synthesis ◽  
2021 ◽  
Author(s):  
Bo Ding ◽  
Qilin Xue ◽  
Shihu Jia ◽  
Hong-Gang Cheng ◽  
Qianghui Zhou
Keyword(s):  
Asymmetric Catalysis ◽  
Kinetic Resolution ◽  
Rapid Development ◽  
Short Review ◽  
Biologically Active ◽  
Metal Catalysis ◽  
Tertiary Alcohols ◽  
Chiral Compounds ◽  
Recent Advances ◽  
Pure Compounds

The kinetic resolution (KR) of racemates is one of the most widely used approaches to access enantiomerically pure compounds. Over the past two decades, catalytic nonenzymatic KR has gained popularity in the field of asymmetric synthesis due to the rapid development of chiral catalysts and ligands in asymmetric catalysis. Chiral tertiary alcohols are prevalent in a variety of natural products, pharmaceuticals, and biologically active chiral compounds. The catalytic nonenzymatic KR of racemic tertiary alcohols is a straightforward strategy to access enantioenriched tertiary alcohols. This short review describes recent advances in catalytic nonenzymatic KR of tertiary alcohols, including organocatalysis and metal catalysis.

scholarly journals Towards Atropoenantiopure N–C Axially Chiral Compounds via Stereoselective C–N Bond Formation

2020 ◽  
Vol 74 (11) ◽  
pp. 883-889
Author(s):  
Johanna Frey ◽  
Sabine Choppin ◽  
Françoise Colobert ◽  
Joanna Wencel-Delord
Keyword(s):  
Medicinal Chemistry ◽  
Bond Formation ◽  
Bond Forming ◽  
Chiral Compounds ◽  
Axially Chiral ◽  
Pure Compounds ◽  
Synthetic Routes ◽  
Metal Catalyzed ◽  
Synthetic Approaches ◽  
Optically Pure

N–C axial chirality, although disregarded for decades, is an interesting type of chirality with appealing applications in medicinal chemistry and agrochemistry. However, atroposelective synthesis of optically pure compounds is extremely challenging and only a limited number of synthetic routes have been designed. In particular, asymmetric N-arylation reactions allowing atroposelective N–C bond forming events remain scarce, although great advances have been achieved recently. In this minireview we summarize the synthetic approaches towards synthesis of N–C axially chiral compounds via stereocontrolled N–C bond forming events. Both organo-catalyzed and metal-catalyzed transformations are described, thus illustrating the diversity and specificity of both strategies.

scholarly journals Nanoengineered chiral Pt-Ir alloys for high-performance enantioselective electrosynthesis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sopon Butcha ◽  
Sunpet Assavapanumat ◽  
Somlak Ittisanronnachai ◽  
Veronique Lapeyre ◽  
Chularat Wattanakit ◽  
...  
Keyword(s):  
High Performance ◽  
Electrochemical Stability ◽  
Lyotropic Liquid Crystal ◽  
Crucial Importance ◽  
Chiral Compound ◽  
Enantiomerically Pure ◽  
Chiral Compounds ◽  
The Past ◽  
Pure Compounds ◽  
Potential Applications

AbstractThe design of efficient chiral catalysts is of crucial importance since it allows generating enantiomerically pure compounds. Tremendous efforts have been made over the past decades regarding the development of materials with enantioselective properties for various potential applications ranging from sensing to catalysis and separation. Recently, chiral features have been generated in mesoporous metals. Although these monometallic matrices show interesting enantioselectivity, they suffer from rather low stability, constituting an important roadblock for applications. Here, a straightforward strategy to circumvent this limitation by using nanostructured platinum-iridium alloys is presented. These materials can be successfully encoded with chiral information by co-electrodeposition from Pt and Ir salts in the simultaneous presence of a chiral compound and a lyotropic liquid crystal as asymmetric template and mesoporogen, respectively. The alloys enable a remarkable discrimination between chiral compounds and greatly improved enantioselectivity when used for asymmetric electrosynthesis (>95 %ee), combined with high electrochemical stability.

Synthesis and Structure Assignment of 2-(4-Methoxybenzyl)cyclohexyl β-D-Glucopyranoside Enantiomers

2006 ◽  
Vol 71 (10) ◽  
pp. 1470-1483 ◽  
Author(s):  
David Šaman ◽  
Pavel Kratina ◽  
Jitka Moravcová ◽  
Martina Wimmerová ◽  
Zdeněk Wimmer
Keyword(s):  
Analytical Data ◽  
Chiral Hplc ◽  
Nmr Analysis ◽  
Target Structure ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
H Nmr ◽  
Structure Assignment ◽  
Related Compounds ◽  
C Nmr

Glucosylation of the cis- and trans-isomers of 2-(4-methoxybenzyl)cyclohexan-1-ol (1a/1b, 2a/2b, 1a or 2a) was performed to prepare the corresponding alkyl β-D-glucopyranosides, mainly to get analytical data of pure enantiomers of the glucosides (3a-6b), required for subsequent investigations of related compounds with biological activity. One of the employed modifications of the Koenigs-Knorr synthesis resulted in achieving 85-95% yields of pure β-anomers 3a/3b, 4a/4b, 3a or 4a of protected intermediates, with several promoters and toluene as solvent, yielding finally the deprotected products 5a/5b, 6a/6b, 5a or 6a as pure β-anomers. To obtain enantiomerically pure β-anomers of the target structure (3a, 4a, 5a and 6a) for unambiguous structure assignment, an enzymic reduction of 2-(4-methoxybenzyl)cyclohexan-1-one by Saccharomyces cerevisiae whole cells was performed to get (1S,2S)- and (1S,2R)-enantiomers (1a and 2a) of 2-(4-methoxybenzyl)cyclohexan-1-ol. The opposite enantiomers of alkyl β-D-glucopyranosides (5b and 6b) were obtained by separation of the diastereoisomeric mixtures 5a/5b and 6a/6b by chiral HPLC. All stereoisomers of the products (3a-6b) were subjected to a detailed 1H NMR and 13C NMR analysis.

scholarly journals Evaluation of Basidiomycetes Wild Strains Grown in Agro-Industrial Residues for Their Anti-Tyrosinase and Antioxidant Potential and for the Production of Biocatalysts

Fermentation ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 19
Author(s):  
Anastasia Zerva ◽  
Nikolaos Tsafantakis ◽  
Evangelos Topakas
Keyword(s):  
Biomass Conversion ◽  
White Rot Fungi ◽  
Ligninolytic Enzymes ◽  
Inhibitory Effect ◽  
Biologically Active ◽  
White Rot ◽  
Oxidative Enzymes ◽  
Industrial Residues ◽  
Pure Compounds ◽  
Wild Strains

White-rot basidiomycetes are the only microorganisms with the ability to produce both hydrolytic (cellulases and hemicellulases) and oxidative (ligninolytic) enzymes for degrading cellulose/hemicellulose and lignin. In addition, they produce biologically active natural products with important application in cosmetic formulations, either as pure compounds or as standardized extracts. In the present work, three wild strains of Basidiomycetes fungi (Pleurotus citrinopileatus, Abortiporus biennis and Ganoderma resinaceum) from Greek habitats were grown in agro-industrial residues (oil mill wastewater, and corn cob) and evaluated for their anti-tyrosinase and antioxidant activity and for the production of biotechnologically relevant enzymes. P. citrinopileatus showed the most interesting tyrosinase inhibitory activity, while A. biennis showed the highest DPPH(2,2-diphenyl-1-picryl-hydrazyl) scavenging potential. Corn cobs were the most appropriate carbon source for maximizing the inhibitory effect of fungal biomasses on both activities, while the use of oil mill wastewater selectively increased the anti-tyrosinase potential of P. citrinopileatus culture filtrate. All strains were found to be preferential lignin degraders, similarly to most white-rot fungi. Bioinformatic analyses were performed on the proteome of the strains P. citrinopileatus and A. biennis, focusing on CAZymes with biotechnological relevance, and the results were compared with the enzyme activities of culture supernatants. Overall, all three strains showed strong production of oxidative enzymes for biomass conversion applications.

scholarly journals Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

2021 ◽  
Vol 17 ◽  
pp. 2729-2764
Author(s):  
Alemayehu Gashaw Woldegiorgis ◽  
Xufeng Lin
Keyword(s):  
Phosphoric Acid ◽  
Asymmetric Catalysis ◽  
Medicinal Chemistry ◽  
High Efficiency ◽  
Biologically Active ◽  
Chiral Compounds ◽  
Chiral Phosphoric Acid ◽  
Wide Range ◽  
Axially Chiral ◽  
Acid Catalyzed

In recent years, the synthesis of axially chiral compounds has received considerable attention due to their extensive application as biologically active compounds in medicinal chemistry and as chiral ligands in asymmetric catalysis. Chiral phosphoric acids are recognized as efficient organocatalysts for a variety of enantioselective transformations. In this review, we summarize the recent development of chiral phosphoric acid-catalyzed synthesis of a wide range of axially chiral biaryls, heterobiaryls, vinylarenes, N-arylamines, spiranes, and allenes with high efficiency and excellent stereoselectivity.

Reshaping the Active Pocket of Esterase Est816 for Resolution of Economically Important Racemates

2021 ◽  
Author(s):  
Xiaolong Liu ◽  
Meng Zhao ◽  
Xinjiong Fan ◽  
Yao Fu
Keyword(s):  
Substrate Specificity ◽  
Industrial Applications ◽  
Pure Compounds ◽  
Optically Pure ◽  
Wide Substrate Specificity

One of the most important industrial applications of bacterial esterases is the production of optically pure compounds. However, the contradiction between the wide substrate specificity and high enantioselectivity of natural...

scholarly journals Development of a Miniaturized 24-well Strawberry Leaf Disk Bioassay for Evaluating Natural Fungicides

2008 ◽  
Vol 3 (7) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Xiaoning Wang ◽  
David E. Wedge ◽  
Nurhayat Tabanca ◽  
Robert D. Johnson ◽  
Stephen J. Cutler ◽  
...  
Keyword(s):  
Leaf Surface ◽  
Higher Plants ◽  
Polar Compounds ◽  
Leaf Disk ◽  
Biologically Active ◽  
Department Of Agriculture ◽  
Lead Compounds ◽  
The Us ◽  
Pure Compounds ◽  
Environmentally Safe

There is great incentive to discover biologically active natural products from higher plants that are more effective than synthetic agrochemicals and are environmentally safe. Research emphasis at the US Department of Agriculture has therefore been on the development of alternative approaches to utilizing natural plant products in pest management. Discovery and evaluation of natural product fungicides is largely dependent upon the availability of miniaturized antifungal bioassays. We report on the development of a miniaturized 24-well leaf disk assay for evaluating plant extracts and pure compounds. Compounds applied directly to the leaf surface can be evaluated in a dose-response for fungicidal activity and phytotoxicity. The assay is sensitive to microgram quantities, can determine chemical sensitivity between fungal isolates, and adaptable to complex mixtures, lipophilic extracts, and non-polar compounds. The use of digital imaging and analytical software provided quantitative data and the ability to fine tune the data analysis. Identification of new potential lead compounds can be repeated quickly in time and real on-the-leaf-surface activity can be evaluated in high throughput formats and published in a reasonable time.

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