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This work constructed chiral nanozymes (Cys@Au/Fe Hops) with high enantioselectivity activity by cysteine-induced synthesis. The nanozymes, proficient in detecting DOPA enantiomers, have been transformed into a test paper sensor, offering enantioselective catalysis and enabling visual chiral detection via a smartphone platform. [Display omitted] • The Chiral Cys@Au/Fe Hops was synthesized using a one-pot method with cysteine as a chiral inducer. • Remarkable enantioselective catalytic activity for DOPA enantiomers by L/D -Cys@Au/Fe Hops. • Steric effects on DOPA enantiomers catalyzed by L/D -Cys@Au/Fe Hops revealed through molecular dynamics simulations. • Development of chiral nanozymes into stable test paper sensor for visual DOPA detection. The development of enantioselective nanozymes holds profound significance in synthesizing chiral compounds and elevating analytical precision. Herein, we have synthesized chiral gold/iron hierarchically organized particles (Cys@Au/Fe Hops) possessing peroxidase-like catalytic activity, through a one-pot method using cysteine as a chiral inducer. The nanozymes exhibited remarkable enantioselective catalytic activity to 3,4-dihydroxy-phenylalanine (DOPA) enantiomer. Notably, L -Cys@Au/Fe Hops, comprising right-handed helical nanopetals, exhibited elevated catalytic efficiency for L -DOPA over D -DOPA, whereas the reverse held for D -Cys@Au/Fe Hops. The molecular dynamics simulations demonstrated hydrogen bonding interactions between the active site and substrate, thereby revealing how steric effects affected the enantioselective catalysis of chiral DOPA by L/D -Cys@Au/Fe Hops. Moreover, the chiral nanozymes were developed into a test paper sensor due to their exceptional stability, which can achieve the visual detection of DOPA enantiomer combined with a smartphone platform. This work is significant in advancing the design and practical utility of highly selective enzyme mimics. [ABSTRACT FROM AUTHOR]

The present study describes the first-time usage of an isolated thermostable Baeyer–Villiger monooxygenase (phenylacetone monooxygenase, PAMO) in the presence of ionic liquids. The stability, activity and selectivity of PAMO as an oxidative enzyme in the presence of different ionic liquids were studied. This revealed that the addition of some specific ionic liquids, such Ammoeng™ 102 and [bmim]MeSO4, can significantly enhance the E-value in the oxidation of racemic benzylketones. Moreover, the use of ionic liquids increases the optimal substrate concentration for performing Baeyer–Villiger oxidation, thereby extending the biocatalytic repertoire of PAMO for synthetic applications. [ABSTRACT FROM AUTHOR]

The use of quasi-enantiomeric substrates and ESI-MS as an analytical tool has made it possible to determine the intrinsic enantioselectivity of chiral catalysts by monitoring catalytic intermediates. In this way, potential problems of methods based on product analysis, which may be caused by catalytically active impurities, partial dissociation of a chiral ligand–metal complex, or a non-catalytic background reaction can be avoided. ESI-MS-based screening is fast, reliable, and operationally simple, as it does not require work-up or purification steps. Moreover, mixtures of catalysts with different molecular masses can be screened simultaneously, which is not possible with methods relying on product analysis. In this way catalyst libraries prepared in one batch by combinatorial methods can be screened without the need to synthesize and purify the catalysts individually. This screening method was successfully applied to Pd-catalyzed allylic substitutions and metal-catalyzed and organocatalytic Diels–Alder reactions. [ABSTRACT FROM AUTHOR]

A chiral cobalt-catalyzed enantioselective aerobic oxidative kinetic resolution of (±)-α-hydroxy esters, using molecular oxygen as a sole oxidant, is reported and a maximum of selectivity factor (s) 31.9 was achieved with >99% enantiomeric excess for unreacted α-hydroxy esters. [ABSTRACT FROM AUTHOR]

Silver(i) salts mediated stereospecific transformation of optically active propargylamines to axially chiral allenes with excellent enantioselectivities (17 examples with 96–99% ee; one substrate with 91% ee) without subsequent racemization. [ABSTRACT FROM AUTHOR]

Chiral bifunctional phase transfer catalysts introducing bis(diarylhydroxymethyl) substituents at 3,3′-positions of the chiral binaphthyl core were successfully applied to asymmetric fluorination of cyclic β-keto esters with high enantioselectivities. [ABSTRACT FROM AUTHOR]

The rhodium-catalyzed intermolecular asymmetric hydroalkoxylation and hydrosulfenylation of diphenylphosphinylallenes gave chiral allylic phosphine oxides substituted with vinyl ether and thioether moieties in high yields with high enantioselectivities. [ABSTRACT FROM AUTHOR]

An efficient, economic and environmentally friendly enantioselective oxidation of racemic benzoins (α-hydroxy ketones) catalyzed by a chiral iron complex has been developed using molecular oxygen as a terminal oxidant with good selectivity and excellent enantiomeric excess. [ABSTRACT FROM AUTHOR]

Chiral pyrrolidinyl sulfonamides have been found to promote the conjugate addition–elimination reaction between activated allylic bromides and 1,3-dicarbonyl compounds with high enantioselectivities and the highly functionalised products can be used to generate a variety of interesting enantiomerically pure compounds viasimple transformations. [ABSTRACT FROM AUTHOR]

Chiral carbon quantum dots (cCQDs) , as a new type of carbon nano-functional material with tunable emission wavelength, superior photostability, low toxicity, biocompatibility and chirality, are playing an increasingly important role in the fields of chemistry, biology and medicine. This paper reviews the preparation methods (one-step and two-step), optical properties (UV, fluorescence, chirality) and applications in chiral catalysis, chiral recognition, targeted imaging as well as other fields, while lists some of the issues and challenges in the research of chiral carbon quantum dots. Finally, due to its good fluorescence and other properties, it is expected that chiral carbon quantum dots will have broad commercial prospects in future applications. [ABSTRACT FROM AUTHOR]

The theory of electron spin has been proposed for a century, but the study of quantum effects in biological molecules is still in its infancy. Chirality-induced spin selectivity (CISS) is a very modern theory that can explain many biochemical phenomena. In this paper, we propose a new theoretical model based on CISS theory and quantum chemistry theory, which can well explain the theoretical explanation of the chiral selectivity of chiral proteins. Moreover, this theory can predict the spin state of corresponding chiral molecules. Taking the L-DOPA and AADC enzymes as examples, this theoretical model elucidates the AADC enzyme's chiral catalysis selectivity and successfully predicts the spin state of L-DOPA and D-DOPA's valence electrons. [ABSTRACT FROM AUTHOR]

Tridentate bis(carboxamide) pincers are key ligands used in catalysis, investigational medicinal inorganic compounds, and materials science. This study examined the atropisomerism of a group of bis(carboxamide) pincers with C2 symmetry to elucidate their physical, chemical, and structural behaviour, paving the way for the application of their metal complexes in different fields. One of the five compounds structurally elucidated by X-ray crystallography, 1c, has a pair of intramolecularly constrained isoquinoline ring substituents and crystallized enantiomerically pure in a chiral Sohncke space group. PM6 calculations of the 3-D potential energy surface for the main atropisomerisation reaction coordinate of 1c indicated that the lowest-energy conformer (atropisomer) has the isoquinoline rings canted out-of-plane by almost +30° and −30° relative to the central pyridine ring. The X-ray structure of 1c is located close to this energy minimum. Circular dichroism (CD) spectroscopy on bulk solid samples confirmed the presence of an excess population of one enantiomer (C2-symmetric atropisomer), most notably for compounds 1c, 1e, and 1f. CD spectra could be recorded for all compounds in solution, similarly reflecting an excess population of one atropisomer. The experimental spectra were confirmed by TD-DFT simulations at the CAM-B3LYP/def2-tzvp level of theory. We conclude that the present group of ligands are worthy of further investigation as chelating agents for metal ions with applications in chiral catalysis or biology. [ABSTRACT FROM AUTHOR]

The widely used combinations of palladium catalysts and chiral phosphoric acids face with the problems of cooperative catalysis and low-cost immobilization of binary catalysts in heterogeneous catalysis, due to the significant decline in the freedom of anchored catalysts. In this paper, the one-pot immobilization of both chiral phosphoric acid (TRIP) and Pd(PPh 3) 4 to hollow mesoporous polystyrene nanospheres (HMPNs) via Friedel-Crafts alkylation is developed to fabricate HMPNs-supported dual organo/metal catalysts (Pd(PPh 3) 4 #TRIP@HMPNs) at a low cost. The efficient cooperative catalysis of anchored TRIP and Pd(PPh 3) 4 with good to excellent yields (89 93 %) and enantioselectivities (80 87 % ee) is achieved in the direct asymmetric α-allylation of aldehydes with allylic alcohols. The higher molar ratio of TRIP to Pd(PPh 3) 4 and a lower crosslinking degree of HMPNs are beneficial to the cooperative catalysis of the anchored catalysts. Overall, this paper showcases a success in solving the key problems in heterogeneous asymmetric metal/oragano catalysis. [Display omitted] • Success in solving the problems in heterogeneous asymmetric metal/oragano catalysis. • One-pot covalent immobilization of dual metal catalyst and chiral organocatalyst. • Efficient heterogeneous organo/metal cooperative catalysis. • Well-shaped hollow mesoporous polystyrene nanospheres as catalyst support. [ABSTRACT FROM AUTHOR]

Time to celebrate: This issue marks the start of the 20th anniversary of Chemistry–A European Journal. The journal has played a major role in changing the face of chemistry. Its history has featured top papers from top authors, among which 13 Nobel Laureates have published over 100 research articles in the journal. [ABSTRACT FROM AUTHOR]

Chiral carbon dots (CCDs) can be widely used in various fields such as chiral recognition, chiral catalysis and biomedicine because of their unique optical properties, low toxicity and good biocompatibility. In addition, CCDs with circularly polarized luminescence (CPL) can be synthesized, thus broadening the prospects of CCDs applications. Since the research on CCDs is still in its infancy, this paper reviews the chiral origin, formation mechanism, chiral evolution, synthesis and emerging applications of CCDs, with a special focus on CCDs with CPL activity. It is hoped that it will provide some reference to solve the current problems faced by CCDs. Finally, the opportunities and challenges of the current research on CCDs are described, and their future development trends have also been prospected. [ABSTRACT FROM AUTHOR]

More information can be found in the Full Paper by H. Westphal, R. Warias et al. GLO:BDBK/15dec21:cctc202101739-toc-0001.jpg PHOTO (COLOR): . gl GLO:BDBK/15dec21:cctc202101739-toc-0001.jpg PHOTO (COLOR): . gl Footnotes 1 These authors contributed equally to this manuscript. Keywords: Analytical methods; Asymmetric catalysis; Heterogeneous catalysis; Lab-on-a-chip; Microreactors EN Analytical methods Asymmetric catalysis Heterogeneous catalysis Lab-on-a-chip Microreactors 5056 5056 1 12/22/21 20211215 NES 211215 B The Front Cover b illustrates a vortex that engulfs entire laboratory equipment and turns it into a single chip unit on the other side. In their Full Paper, H. Westphal, R. Warias et al. present a method to study immobilized organocatalysts and their performance in stereoselective transformations. [Extracted from the article]

Chiral primary amine–squaramides have not been extensively studied to date in the field of organocatalysis. In this paper, novel chiral squaramides derived from natural product stevioside were developed. Both enantiomers of a series of γ-nitroaldehydes were generated by using these squaramide catalysts for the Michael addition reaction of isobutyraldehyde to nitroolefins. This asymmetric reaction proceeded well to afford the desired products in high yields (up to 98%) with high to excellent enantioselectivities (up to 99% ee). [ABSTRACT FROM AUTHOR]

The functionalization of (R,R)-S,S′-di-tert-butylferrocene-1,1′-disulfoxide by deprotolithiation-electrophilic trapping sequences was studied towards polysubstituted, enantiopure derivatives for which the properties were determined. While the 2,2′-disubstituted ferrocene derivatives were obtained as expected, subsequent functionalization of the 2,2′-di(phenylthio) and 2,2′-bis(trimethylsilyl) derivatives occurred primarily at the 4- or 4,4′-positions. This unusual regioselectivity was discussed in detail in light of pKa values and structural data. The less sterically hindered 2,2′-difluorinated derivative yielded the expected 1,1′,2,2′,3,3′-hexasubstituted ferrocenes by the deprotometallation-trapping sequence. Further functionalization proved possible, leading to early examples of 1,1′,2,2′,3,3′,4,4′-octa, nona and even decasubstituted ferrocenes. Some of the newly prepared ferrocene-1,1′-disulfoxides were tested as ligands for enantioselective catalysis and their electrochemical properties were investigated. [ABSTRACT FROM AUTHOR]

Karlotoxin 2 (KmTx2) is a marine natural product isolated from the dinoflagellate Karlodinium veneficum. The absolute configuration of KmTx2 was determined by NMR analysis in combination with degradation of the natural product, and the absolute configuration at C49 was revised by computational analysis. On the other hand, we reported revision of the absolute configuration of amphidinol 3 (AM3), whose structure is similar to that of KmTx2, by comparing NMR data of the synthesized partial structures and total synthesis of AM3. In this paper, we report the synthesis of the partial structures of KmTx2 corresponding to the C30−C63 section, and the diastereomer at C37, C41−C43, and C45−C49, which is hypothetically proposed on the basis of the revised structure of AM3. Comparison of the NMR data of the synthetic specimens with those of the natural product suggested that the absolute configuration of KmTx2 is revised to be 37R, 41R, 42R, 43R, 45R, 46R, 47R, 48S, and 49S. [ABSTRACT FROM AUTHOR]

In this paper, an approach is proposed for determining the ratio of prototropic annular tautomers of organosilicon 1,2,3-triazoles, which are hardly experimentally determined in solution by NMR technique. The comparison of experimental and calculated (at the CCSD level) NMR chemical shifts allows the predominant tautomer in the equilibrium mixture to be determined. [ABSTRACT FROM AUTHOR]

Biological systems are homochiral, raising the question of how a racemic mixture of prebiotically synthesized biomolecules could attain a homochiral state at the network level. Based on our recent results, we aim to address a related question of how chiral information might have flowed in a prebiotic network. Utilizing the crystallization properties of the central ribonucleic acid (RNA) precursor known as ribose-aminooxazoline (RAO), we showed that its homochiral crystals can be obtained from its fully racemic solution on a magnetic mineral surface due to the chiral-induced spin selectivity (CISS) effect [Ozturk et al., arXiv:2303.01394 (2023)]. Moreover, we uncovered a mechanism facilitated by the CISS effect through which chiral molecules, such as RAO, can uniformly magnetize such surfaces in a variety of planetary environments in a persistent manner [Ozturk et al., arXiv:2304.09095 (2023)]. All this is very tantalizing because recent experiments with tRNA analogs demonstrate high stereoselectivity in the attachment of L-amino acids to D-ribonucleotides, enabling the transfer of homochirality from RNA to peptides [Wu et al., J. Am. Chem. Soc. 143, 11836 (2021)]. Therefore, the biological homochirality problem may be reduced to ensuring that a single common RNA precursor (e.g., RAO) can be made homochiral. The emergence of homochirality at RAO then allows for the chiral information to propagate through RNA, then to peptides, and ultimately through enantioselective catalysis to metabolites. This directionality of the chiral information flow parallels that of the central dogma of molecular biology—the unidirectional transfer of genetic information from nucleic acids to proteins [F. H. Crick, in Symposia of the Society for Experimental Biology, Number XII: The Biological Replication of Macromolecules, edited by F. K. Sanders (Cambridge University Press, Cambridge, 1958), pp. 138-163; and F. Crick, Nature 227, 561 (1970)]. [ABSTRACT FROM AUTHOR]

The cycloisomerization reaction of γ‐alkynoic acids mediated by transition‐metal catalysts has become a successful strategy for accessing enol lactones during the past few years. In their Full Paper on page 545, Cecilio Alvarez‐Toledano and co‐workers developed a fast and efficient protocol for the regio and diastereoselective cycloisomerization of β‐hydroxy‐γ‐alkynoic acids, catalyzed by the inexpensive and air‐stable catalyst CuBr (5 mol%) in water under microwave heating. This method provides rapid access to a variety of highly functionalized Z‐enol‐γ‐lactones in good yields under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Asymmetric catalysis for enantioselective intramolecular hydroamination of alkenes is a critical method in the construction of enantioenriched nitrogen-containing rings, often prevalent in biologically active compounds and natural products. Herein, we demonstrate a facile enantioselective intramolecular hydroamination of alkenes for the synthesis of chiral pyrrolidine, piperidine, and indoline moieties, using a manganese (II) chiral aprotic cyclic urea catalyst. The cyclic ligand hinders the inversion of the N atom of the urea and effectively discriminate between the enantiomers of substrates. High-resolution mass spectrometry, deuterium labeling experiments, and molecular orbital energy analysis clearly reveal the intermediates and mechanism of the transformation. As a key step, oxygen coordination by chiral aprotic urea presents a robust control over the asymmetric intra-HA reaction through the involvement of a convergent assembly of two vital intermediates (Mn-N and C-Mn-Br), providing access to chiral cyclic amine systems in high yields with excellent enantioselectivity. Nitrogen-containing rings containing chiral carbon centers are a staple of bioactive molecules and natural products of interest, and synthetic methodologies for their development are a continual focus of organic chemists. Here, the authors disclose a protocol for the synthesis of enantioenriched saturated azacycles, via intramolecular hydroamination of alkenes, using a chiral cyclic urea ligand with manganese. [ABSTRACT FROM AUTHOR]

The work reported within this paper describes an example of the application of bimetallic catalysts system in allylic substitution reactions. The development of new nucleophiles and the control of enantio‐ and diastereoselectivity are the main research topics in this area. An improvement in the reactivity and diastereoselectivity has been realized for the dual Ir/Cu catalyzed allylic alkylation of inactive prochiral nucleophiles, under mild reaction conditions. Furthermore, the choice of the metallacyclic iridium complex and chiral Cu‐Phox complex combination allows for access to all four stereoisomers from the same starting materials with excellent enantioselectivity and diastereoselectivity (up to >99% ee and >20:1 dr). Significantly, this method provides a stereodivergent access to 2‐amino‐3‐methylpent‐4‐acid ester, an important fragment for the synthesis of Halipeptin A. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • L -cysteine modified chiral carbon quantum dots (cCQDs) were synthesized. • cCQDs-embedded nanopaper is developed for enantioselective sensing. • Photoluminescent enantioselective sensing of lysine enantiomers is achieved. • The enantiomeric percentage can be determined by the proposed sensor. Abstract The production and application of chiral nanomaterials are expanding to understand the nature of chiral interactions and to detect chiral molecules due to the chirality is a fundamental characteristics of life processes. With the new advances in optical sensors by combining the advantages of optical signaling unit and sensing platform, new avenues can be opened to produce simple and useful devices for chiral sensor applications. Here, we report construction of nanoscale chirality of carbon quantum dots (CQDs) by functionalization with L -cysteine and application for paper-based sensors. Within this respect, nanopaper made of cellulose nanofibers was prepared and the produced chiral carbon quantum dots (cCQDs) were embedded into nanopaper to gain photoluminescence properties. The chiral sensing behavior of cCQDs was investigated in solution phase and nanopaper. cCQDs exhibited an enantioselective response towards L -lysine among the tested enantiomers of amino acids with a LOD value of 0.30 mM and 0.97 mM for solution phase and nanopaper, respectively. [ABSTRACT FROM AUTHOR]

In the present paper, we describe several pathways employing immobilized lipase from Candida antarctica B (CAL‐B) as biocatalyst to prepare easily both enantiomers of 3‐(1‐hydroxyethyl)phenol. We have applied hydrolysis with Na2CO3 in organic media under mild conditions. The reaction parameters solvent effect, amount of lipase, and Na2CO3 were examined with 3‐(1‐acetoxyethyl)phenyl acetate as substrate. In alkaline hydrolysis, (R)‐3‐(1‐hydroxyethyl)phenol was obtained with ee = 99% and (S)‐(−)‐3‐(1‐acetoxyethyl)phenol with ee = 98% at optimal conversion (c = 50%) and high selectivity (E > 200). Two other deacylation reactions were compared: alcoholysis with MeOH and with NEt3. The acylation of 3‐(1‐hydroxyethyl)phenol with vinyl acetate was also examined. Alkaline hydrolysis gave the best results, while good regioselectivity and enantioselectivity were observed in alcoholysis and acylation reactions. Finally, (S)‐ and (R)‐3‐(1‐hydroxyethyl)phenol (ee > 98%), key intermediates for the synthesis of important drugs, were prepared from the corresponding racemic diacetate through alkaline hydrolysis. [ABSTRACT FROM AUTHOR]

The quantification of the enantiomeric fraction ( EF ) during the biodegradation process is essential for environmental risk assessment. In this paper the enantioselective biodegradation of ibuprofen, IBU, and ketoprofen, KET, two of the drugs most consumed, was evaluated. Biodegradation experiments were performed in batch mode using a minimal salts medium inoculated with an activated sludge (collected from a Valencian Waste Water Treatment Plant) and supplemented with the racemate of each compound. The inoculum activity was verified using fluoxetine as reference compound. The experimental conditions used (analyte concentration and volume of inoculum) were chosen according to OECD guidelines. In parallel, the optical density at 600 nm was measured to control the biomass growth and to connect it with enantioselectivity. Two RPLC methods for chiral separations of IBU and KET using polysaccharides-based stationary phases were developed. Novel calculations and adapted models, using directly the chromatographic peak areas as dependent variable, were proposed to estimate significant parameters related to the biodegradation process: biodegradation ( BD ) and EF values at given time, half-life times of (R)- and (S)-enantiomers, number of days to reach a complete BD and the minimum EF expected. The modelled BD and EF curves fitted adequately the data ( R 2  > 0.94). The use of these new equations provided similar results to those obtained using concentration data. However, the use of chromatographic peak areas data, eliminates the uncertainty associated to the use of the calibration curves. The results obtained in this paper indicate that an enantiorecognition towards IBU enantiomers by the microorganisms present in the activated sludge used in this study occurred, being the biodegradation of (R)-IBU higher than that of (S)-IBU. For KET, non-enantioselective biodegradation was observed. [ABSTRACT FROM AUTHOR]

Several chiral reagents including cyclodextrins (CDs) and derivatives, crown ethers, proteins, chiral surfactants, and polymers have been involved in dual-selector systems for enantioseparation of a series of compounds by capillary electrophoresis (CE). In this paper, chondroitin sulfate D-based dual-selector system (CSD/CM-β-CD) was firstly established and investigated for the enantioseparation of six basic racemic drugs in capillary electrophoresis. Compared to the single-selector systems, synergistic effect and significantly improved separations for all tested analytes were observed in CSD/CM-β-CD system. The effect of several parameters, such as buffer pH, chiral selector concentration, and applied voltage, was systematically optimized. Meanwhile, to investigate the possible chiral recognition mechanisms in CSD/CM-β-CD synergistic system, we tried to apply the molecular docking method to simulate the host-guest binding procedures of the polysaccharide-based dual system for the first time. The difference in binding free energy was found to correspond to the chiral selectivity factor. The existence of CSD-CM-β-CD complex may give rise to a higher discriminatory ability against the enantiomers, indicating the synergistic effect in CSD/CM-β-CD system.ᅟ [ABSTRACT FROM AUTHOR]

Poly(L-lactide) (PLLA) porous materials have become increasingly important for practical applications. However, the methods for preparing PLLA-based porous particles are quite limited. The chirality of PLLA materials remains scarcely explored even though PLLA is a well-known chiral polymer. In this paper, we establish an unprecedented, facile approach for preparing PLLA particles with lamellar structures by precipitation polymerization. By adjusting polymerization conditions (solvent and temperature), a series of PLLA particles with tunable morphology was fabricated. The resulting particles were characterized by SEM, CD, XRD, DSC, and GPC measurements. We further explored chiral resolution ability of the PLLA particles used as chiral additive to induce enantioselective crystallization. According to SEM, CD, and XRD characterizations, PLLA particles show considerable enantioselectivity and preferentially induce L-threonine to crystallize from the racemic solution. Besides, enhancing the crystallinity of PLLA particles is beneficial for improving the particles’ enantiodifferentiating ability. The present study provides a versatile platform for developing novel PLLA materials, which deserve more attention as chiral biomaterials. [ABSTRACT FROM AUTHOR]

Abstract: The development of silica‐supported molecular catalysts for tandem reactions is an important research direction of heterogeneous catalysis. Besides their significant merits in sustainable catalytic processes, numerous strategies have been utilized to construct silica‐supported molecular catalysts. Here, we emphasize tandem reactions and summarize the recent advances in sequential organic transformations. This paper is composed of four parts. The beginning part introduces silica as supports. The second part provides a large number of examples for the construction of non‐chiral molecular catalysts used for tandem reactions. The third part offers an outline for the construction of chiral molecular catalysts used for enantioselective tandem reactions. Finally, the perspectives for the further development of silica‐supported molecular catalysts for tandem reactions are addressed. [ABSTRACT FROM AUTHOR]

A concise method for the preparation of new 3,4,5,6-tetrahydropyrimidinium salts was presented in this paper. Further application of these salts in asymmetric diethylzinc addition of arylaldehydes was explored, giving the corresponding chiral second alcohols in good yields and moderate enantioselectivities. [ABSTRACT FROM AUTHOR]

Abstract: The asymmetric [2+2] cycloaddition reactions of alkenes with alkynes are interesting as it has provided a powerful method for the construction of fused and strained cyclobutenes with multiple chiral centers. In this paper, we report the establishment of a dual catalysts system comprising nickel and zinc, which allowed the asymmetric [2+2] cycloaddition reactions of azabenzonorbornadienes with terminal alkynes in good yields and excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

With increasing concerns in sustainable development, biocatalysis has been recognized as a competitive alternative to traditional chemical routes in the past decades. As nature's biocatalysts, enzymes are able to catalyze a broad range of chemical transformations, not only with mild reaction conditions but also with high activity and selectivity. However, the insufficient activity or enantioselectivity of natural enzymes toward non-natural substrates limits their industrial application, while directed evolution provides a potent solution to this problem, thanks to its independence on detailed knowledge about the relationship between sequence, structure, and mechanism/function of the enzymes. A proper high-throughput screening (HTS) method is the key to successful and efficient directed evolution. In recent years, huge varieties of HTS methods have been developed for rapid evaluation of mutant libraries, ranging from in vitro screening to in vivo selection, from indicator addition to multi-enzyme system construction, and from plate screening to computation- or machine-assisted screening. Recently, there is a tendency to integrate directed evolution with metabolic engineering in biosynthesis, using metabolites as HTS indicators, which implies that directed evolution has transformed from molecular engineering to process engineering. This paper aims to provide an overview of HTS methods categorized based on the reaction principles or types by summarizing related studies published in recent years including the work from our group, to discuss assay design strategies and typical examples of HTS methods, and to share our understanding on HTS method development for directed evolution of enzymes involved in specific catalytic reactions or metabolic pathways. [ABSTRACT FROM AUTHOR]

The synthesis of chiral α-azaheteroaryl oxiranes via enantioselective catalysis is a formidable challenge due to the required complex stereoselectivity and diverse N-heterocyclic structures. These compounds play a crucial role in developing bioactive molecules, where precise chirality significantly influences biological activity. Here we show that using chiral phosphoric acid as a catalyst, our method efficiently addresses these challenges. This technique not only achieves high enantio- and diastereoselectivity but also demonstrates superior chemo- and stereocontrol during the epoxidation of alkenyl aza-heteroarenes. Our approach leverages a synergistic blend of electrostatic and hydrogen-bonding interactions, enabling the effective activation of both substrates and hydrogen peroxide. The resulting chiral oxiranes exhibit enhanced diversity and functionality, aiding the construction of complex chiral azaaryl compounds with contiguous stereocenters. Kinetic and density functional theory studies elucidate the mechanism, highlighting chiral phosphoric acid's pivotal role in this intricate enantioselective process. Chiral azaarenes hold critical importance in pharmaceutical research due to their significant impact on drug efficacy and selectivity. Herein, the authors report the synthesis of chiral α-azaheteroaryl oxiranes via catalytic enantioselective epoxidation of alkenyl aza-heteroarenes using chiral phosphoric acid and hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Herein, an enantioselective desymmetrization of cyclic keto sulfonium salts through enantioselective deprotonation/ring opening process by anion-binding catalysis is presented. We report a squaramide/HCO3- complex as catalytic active species which is able to stereo-differentiate two enantiomeric protons, triggering the ring opening event taking advantage of the great tendency of sulfonium salts to act as leaving groups. Thus, this desymmetrization methodology give rise to β-methylsulfenylated sulfa-Michael addition type products with excellent yields and very good enantioselectivities. The bifunctional organocatalyst has been demonstrated to be capable of activating simultaneously the base and the keto sulfonium salt by DFT calculations and experimental proofs. Although anion-binding processes are well-known for their crucial role in molecular recognition, this type of phenomenon has only recently been utilized for catalysis. Here, the authors present an enantioselective desymmetrization of cyclic keto sulfonium salts through enantioselective deprotonation/ring opening process by anion-binding catalysis. [ABSTRACT FROM AUTHOR]

Heterogeneous asymmetric catalysis is an important strategy for the industrial production of chiral compounds. Herein, we reported a polymer-bound Xu-Phos-derived palladium catalyst that shows good performance in heterogeneous asymmetric reductive Heck reaction of allyl aryl ethers. This heterogeneous catalyst was easily prepared by efficient immobilization of the sulfonamide phosphine ligand (Xu-Phos) in the cross-linked polystyrene via copolymerization, and exhibits similar catalytic activity and enantioselectivity to that of the homogeneous catalyst. Moreover, the heterogeneous catalyst system is proved to be easily recovered and reused several times without losing catalytic activity obviously. [ABSTRACT FROM AUTHOR]

Core-shell structured magnetic wrinkled organosilica-based metal-enzyme integrated catalysts were synthesized, and their catalytic performances were studied in the chemoenzymatic dynamic kinetic resolution of chiral amines in an organic solvent, as well as in the chemoenzymatic synthesis of chiral alcohols in water. Structureperformance studies revealed the important influence of their tunable structure and composition on the optimization of activity, stability, and recyclability in chemoenzymatic catalysis. [ABSTRACT FROM AUTHOR]

The enantioselective, potentiomeric membrane electrode based on vancomycin and teicoplanin modified with acetonitrile were proposed for the assay of (S)-(+)-ibuprofen. The linear concentration ranges for the proposed enantioselective membrane electrodes were 10-2 to 10-4 and 10-2 to 10-6 mol/Lfor electrodes based on vancomycin and acetonitrile modified teicoplanin, respectively, with slopes of 58.5 and 57.0 mV/decade of concentration, respectively. The proposed electrodes could be employed reliably for the assay of (S)-(+)-ibuprofen raw material and in its pharmaceutical formulations, Myprodol capsules and Nurofen tablets. The surfaces of the electrodes are stable and easily renewable by polishing on alumina paper. [ABSTRACT FROM AUTHOR]

Three enantioselective, potentiometric carbon paste electrodes (EPCPEs) based on carbon paste impregnated with (1,2‐methanofullerene C60)‐61‐carboxylic acid (I), diethyl (1,2‐methanofullerene C60)‐61‐61‐dicarboxylate (II), and tert‐butyl (1,2‐methanofullerene C60)‐61‐carboxylic acid (III) are reported. Response characteristics showed that the proposed electrodes could be reliably used in the assay of S‐clenbuterol raw material and in serum samples. The surfaces of the electrodes are stable and easily renewable by simply polishing on an alumina paper. [ABSTRACT FROM AUTHOR]

A lipase-mediated synthesis of all four enantiomers of isoaminile is reported. The key issues of the paper are: (i) enantioselective acetylation of allylic alcohol (E)-(±)-5 to give (E,S)-5 (ee = 92%) and (E,R)-6 (ee >99%); (ii) Claisen-Johnson rearrangement of R and S enantiomers of 5 to generate the quaternary benzylic stereocenter; (iii) chromatographic separation of aldehyde diastereoisomers; (iv) X-ray structure of aldehyde (2R,4R)-10; (v) unpredicted formation of lactone 12 during the hydrolysis of 11. [ABSTRACT FROM AUTHOR]

Michael addition of P-H compounds, such as phosphanes, phosphane oxides and phosphonates, is a practical tool to form P-C bonds. The stereochemistry of the newly formed compounds can be influenced either by using chiral starting materials or chiral catalysts. Since the former method is limited to the readily available opticallyactive derivatives, catalytic options are more common. Enantioenriched P-C compounds can have biological activity; therefore, they are pharmaceutically valuable molecules. In this paper, an overview is provided on the conjugate addition of P-H compounds according to the type of the phosphorus derivatives. [ABSTRACT FROM AUTHOR]

Microemulsions provide a unique opportunity to tailor the polarity and liquid confinement in asymmetric catalysis via nanoscale polar and nonpolar domains separated by a surfactant film. For chiral diene Rh complexes, the influence of counterion and surfactant film on the catalytic activity and enantioselectivity remained elusive. To explore this issue chiral norbornadiene Rh(X) complexes (X=OTf, OTs, OAc, PO2F2) were synthesized and characterized by X‐ray crystallography and theoretical calculations. These complexes were used in Rh‐catalyzed 1,2‐additions of phenylboroxine to N‐tosylimine in microemulsions stabilized either exclusively by n‐octyl‐β‐D‐glucopyranoside (C8G1) or a C8G1‐film doped with anionic or cationic surfactants (AOT, SDS and DTAB). The Rh(OAc) complex showed the largest dependence on the composition of the microemulsion, yielding up to 59 % (90 %ee) for the surfactant film doped with 5 wt% of AOT as compared to 52 % (58 %ee) for neat C8G1 at constant surfactant concentration. Larger domains, determined by SAXS analysis, enabled further increase in yield and selectivity while the reaction rate almost remained constant according to kinetic studies. [ABSTRACT FROM AUTHOR]

The development of heterogeneous catalysts for asymmetric synthesis is one of the most challenging topics in chemistry, as it allows obtaining enantiomerically pure compounds. Recently, metal layers incorporating molecular chiral cavities, obtained by electroreduction of a metal source in the simultaneous presence of a non‐ionic surfactant and asymmetric molecules, have been proposed for a wide range of applications, including enantioselective electroanalysis and electrosynthesis, as well as chiral separation. In contrast to this previous work, solely based on electrochemical phenomena, herein we designed and employed nanostructured chiral encoded Pt−Ir alloys, supported on high surface area nickel foams, as heterogeneous catalysts for the asymmetric hydrogenation of aromatic ketones. Fine‐tuning the experimental conditions allows achieving very high enantioselectivity (>80%), combined with improved catalyst stability. [ABSTRACT FROM AUTHOR]

Choosing the optimal catalyst for a new transformation is challenging because the ideal molecular requirements of the catalyst for one reaction do not always simply translate to another. Large groups at the 3,3′ positions of the binaphthol rings are important for efficient stereoinduction but if they are too large this can lead to unusual or poor results. By applying a quantitative steric assessment of the substituents at the 3,3′ positions of the binaphthol ring, we have systematically studied the effect of modulating this group on enantioselectivity for a wide range of reactions involving imines, and verified this analysis using ONIOM calculations. We have shown that in most reactions, the stereochemical outcome depends on both proximal and remote sterics. Summarising detailed calculations into a simple qualitative model identifies and explains the steric features required for high selectivity. This model is consistent with seventy seven papers reporting reactions (over 1000 transformations in total), and provides a straightforward decision tree for selecting the best catalyst. [ABSTRACT FROM AUTHOR]

The catalytic, enantioselective oxidative cyclization of naphthol-derived carboxylic acids mediated by chiral hypervalent iodine reagents has been studied extensively in the recent past, but analogous reactions of non-carboxylic substrates are yet unknown. This paper describes a catalytic, enantioselective, hypervalent iodine-promoted oxidative cycloetherification reaction of naphtholic alcohols. The new process relies on a variant of the Uyanik-Ishihara catalyst, in which the stereogenic centers have been relocated closer to the iodine atom. The new catalyst design affords optical yields comparable to those available with Uyanik-Ishihara iodides, but chemical yields are sensibly higher, at least with the tests substrates. An even more problematic reaction is the catalytic, enantioselective oxidative cyclization of naphtholic sulfonamides. In this case, the new catalyst affords significantly higher optical inductions than Uyanik-Ishihara iodides. The kinetic resolution of particular naphtholic alcohols is demonstrated. The absolute configuration of a numver of enantioenriched compounds obtained in this study was ascertained by X-ray diffractometry. [ABSTRACT FROM AUTHOR]