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A ruthenium‐catalyzed reductive amination via asymmetric transfer hydrogenation (ATH) has been used to perform an efficient dynamic kinetic resolution (DKR) of N‐aryl 2‐formyl pyrroles decorated with a phosphine moiety positioned at the ortho' position. The strategy relies on the labilization of the stereogenic axis in the substrate facilitated by a transient Lewis acid‐base interaction (LABI) between the carbonyl carbon and the phosphorus center. The reaction features broad substrate scope of aliphatic amines and N‐aryl pyrrole scaffolds, and proceeds under very mild conditions to afford P,N atropisomers in good to high yields and excellent enantioselectivities (up to 99 % ee) for both diphenyl and dicyclohexylphosphino derivatives. [ABSTRACT FROM AUTHOR]

A general and highly enantioselective method for the preparation of tetra‐substituted 3‐hydroxyphthalide esters via isothiourea‐catalysed acylative dynamic kinetic resolution (DKR) is reported. Using (2S,3R)‐HyperBTM (5 mol %) as the catalyst, the scope and limitations of this methodology have been extensively probed, with high enantioselectivity and good to excellent yields observed (>40 examples, up to 99 %, 99 : 1 er). Substitution of the aromatic core within the 3‐hydroxyphthalide skeleton, as well as aliphatic and aromatic substitution at C(3), is readily tolerated. A diverse range of anhydrides, including those from bioactive and pharmaceutically relevant acids, can also be used. The high enantioselectivity observed in this DKR process has been probed computationally, with a key substrate heteroatom donor O⋅⋅⋅acyl‐isothiouronium interaction identified through DFT analysis as necessary for enantiodiscrimination. [ABSTRACT FROM AUTHOR]

The development of methods to allow the selective acylative dynamic kinetic resolution (DKR) of tetra‐substituted lactols is a recognised synthetic challenge. In this manuscript, a highly enantioselective isothiourea‐catalysed acylative DKR of tetra‐substituted morpholinone and benzoxazinone‐derived lactols is reported. The scope and limitations of this methodology have been developed, with high enantioselectivity and good to excellent yields (up to 89 %, 99 : 1 er) observed across a broad range of substrate derivatives incorporating substitution at N(4) and C(2), di‐ and spirocyclic substitution at C(5) and C(6), as well as benzannulation (>35 examples in total). The DKR process is amenable to scale‐up on a 1 g laboratory scale. The factors leading to high selectivity in this DKR process have been probed through computation, with an N−C=O⋅⋅⋅isothiouronium interaction identified as key to producing ester products in highly enantioenriched form. [ABSTRACT FROM AUTHOR]

Axially chiral biaryl δ‐amino acids possess significantly different conformational properties and chiral environment from centrally chiral amino acids, therefore, have drawn considerable attention in the fields of synthetic and medicinal chemistry. Herein, a novel chiral phenanthroline‐potassium catalyst has been developed by constructing a well‐organized axially chiral ligand composed of one 1,10‐phenanthroline unit and two axially chiral 1,1′‐bi‐2‐naphthol (BINOL) units. In the presence of this catalyst, good to excellent yields and enantioselectivities (up to 99 % yield, 98 : 2 er) have been achieved in the ring‐opening alcoholytic dynamic kinetic resolution of a variety of biaryl lactams, thereby providing an efficient protocol for catalytic asymmetric synthesis of unnatural axially chiral biaryl δ‐amino acid derivatives. [ABSTRACT FROM AUTHOR]

The conceptual merger of relay catalysis with dynamic kinetic resolution strategy is reported to enable regio‐ and enantioselective C(sp3)‐H bond arylation of aliphatic alcohols, forming enantioenriched β‐aryl alcohols typically with >90 : 10 enantiomeric ratios (up to 98 : 2 er) and 36–74 % yields. The starting materials bearing neighbouring stereogenic centres can be converted to either diastereomer of the β‐aryl alcohol products, with >85 : 15 diastereomeric ratios determined by the catalysts. The reactions occur under mild conditions, ensuring broad compatibility, and involve readily available aryl bromides, an inorganic base, and commercial Ru‐ and Pd‐complexes. Mechanistic experiments support the envisioned mechanism of the transformation occurring through a network of regio‐ and stereoselective processes operated by a coherent Ru/Pd‐dual catalytic system. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Optically active phthalides are prevalent in many natural and bioactive products. Herein, a novel dynamic kinetic resolution of isobenzofuranone derivatives through palladium‐catalyzed asymmetric allylic alkylation has been developed to synthesize phthalide derivatives bearing vicinal quaternary and tertiary stereocenters with high yields, showing excellent chemo‐, enantio‐ and diastereoselectivity. Furthermore, gram‐scale experiment underwent smoothly and the transformation of product could build a bridged bicyclic skeleton. [ABSTRACT FROM AUTHOR]

Chiral guanidine-catalyzed acylative and silylative dynamic kinetic resolutions of 6-hydroxy-2 H -pyran-3(6 H)-one were achieved. We succeeded in developing a non-enzymatic acylative dynamic kinetic resolution of 6-hydroxy-2 H -pyran-3(6 H)-one with high enantioselectivity, which could be improved by recrystallization. In contrast, the non-enzymatic silylative dynamic kinetic resolution of 6-hydroxy-2 H -pyran-3(6 H)-one was accomplished with a moderate selectivity for the first time. [ABSTRACT FROM AUTHOR]

Axially chiral biaryl compounds are ubiquitous scaffolds in natural products, bioactive molecules, chiral ligands and catalysts, but biocatalytic methods for their asymmetric synthesis are limited. Herein, we report a highly efficient biocatalytic route for the atroposelective synthesis of biaryls by dynamic kinetic resolution (DKR). This DKR approach features a transient six‐membered aza‐acetal‐bridge‐promoted racemization followed by an imine reductase (IRED)‐catalyzed stereoselective reduction to construct the axial chirality under ambient conditions. Directed evolution of an IRED from Streptomyces sp. GF3546 provided a variant (S‐IRED‐Ss‐M11) capable of catalyzing the DKR process to access a variety of biaryl aminoalcohols in high yields and excellent enantioselectivities (up to 98 % yield and >99 : 1 enantiomeric ratio). Molecular dynamics simulation studies on the S‐IRED‐Ss‐M11 variant revealed the origin of its improved activity and atroposelectivity. By exploiting the substrate promiscuity of IREDs and the power of directed evolution, our work further extends the biocatalysts’ toolbox to construct challenging axially chiral molecules. [ABSTRACT FROM AUTHOR]

An efficient RuPHOX−Ru catalyzed asymmetric cascade hydrogenation of 3‐substituted chromones has been achieved under mild reaction conditions, affording the corresponding chiral 3‐substituted chromanols in high yields with excellent enantio‐ and diastereoselectivities (up to 99 % yield, >99 % ee and >20 : 1 dr). Control reactions and deuterium labelling experiments revealed that a dynamic kinetic resolution process occurs during the subsequent hydrogenation of the C=O double bond, which is responsible for the high performance of the asymmetric cascade hydrogenation. The resulting products allow for several transformations and it was shown that the protocol provides a practical and alternative strategy for the synthesis of chiral 3‐substituted chromanols and their derivatives. [ABSTRACT FROM AUTHOR]

Metal‐enzyme integrated catalysts (MEICs) that combine metal and enzyme offer great potential for sustainable chemoenzymatic cascade catalysis. However, rational design and construction of optimal microenvironments and accessible active sites for metal and enzyme in individual nanostructures are necessary but still challenging. Herein, Pd nanoparticles (NPs) and Candida antarctica lipase B (CALB) are co‐immobilized into the pores and surfaces of covalent organic frameworks (COFs) with tunable functional groups, affording Pd/COF‐X/CALB (X = ONa, OH, OMe) MEICs. This strategy can regulate the microenvironment around Pd NPs and CALB, and their interactions with substrates. As a result, the activity of the COF‐based MEICs in catalyzing dynamic kinetic resolution of primary amines is enhanced and followed COF‐OMe > COF‐OH > COF‐ONa. The experimental and simulation results demonstrated that functional groups of COFs modulated the conformation of CALB, the electronic states of Pd NPs, and the affinity of the integrated catalysts to the substrate, which contributed to the improvement of the catalytic activity of MEICs. Further, the MEICs are prepared using COF with hollow structure as support material, which increased accessible active sites and mass transfer efficiency, thus improving catalytic performance. This work provides a blueprint for rational design and preparation of highly active MEICs. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Phthalides serve as core structures pervasive in a wide array of natural products and drug molecules, which display a diverse array of biological activities. We report herein a highly efficient dynamic kinetic resolution of 3‐hydroxyphthalides by chiral isothioureas (ITUs) catalyzed asymmetric acylation, facilitating the effective synthesis of a variety of chiral phthalidyl esters with good yields and enantioselectivities. Notably, this reaction features mild reaction conditions, expansive substrate scope as well as good functional group compatibility. In addition, the practicality of this method is underscored by the large‐scale synthesis, reduced catalyst loading experiment and the synthesis of the chiral phthalidyl ester prodrug. [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. Structure-performance studies revealed the important influence of their tunable structure and composition on the optimization of activity, stability, and recyclability in chemoenzymatic catalysis.

P‐stereogenic benzo‐fused heterocycles is a privileged skeleton due to their outstanding catalytic properties and bioactivities. However, their enantioselective synthesis is still underdeveloped. Here we demonstrate the use of easily accessible racemic H−P(O) compounds as starting materials and commercial chiral N1, N2‐dimethyl‐1,2‐diphenylethane‐1,2‐diamine ligand in combination with Cu(I) catalysts to enable an attractive dynamic kinetic C(sp2)−P cross‐coupling reaction. This protocol not only exhibits a broad substrate scope but also provides general access to a diverse range of useful P‐stereogenic five‐, six‐, seven‐ and eight‐membered benzo‐fused O, P‐ containing heterocycles with good to high yields and enantioselectivities. [ABSTRACT FROM AUTHOR]

Bio‐catalysis represents a highly efficient and stereoselective method for the synthesis of valuable chiral compounds, however, the poor stability and limited reaction types of free enzymes restrict their wide application in industrial production. In this work, to overcome these problems, a multifunctional photoenzymatic nanoreactor CALB@COF‐Ir was developed through the encapsulation of Candida antarctica lipase B (CALB) in a photosensitive covalent organic framework COF‐Ir. This bio‐nanocluster serves as efficient catalysts in asymmetric dynamic kinetic resolution (DKR) of secondary amines to give a series of chiral amines in high yields (up to 99 %) and enantioselectivities (up to 99 % ee). The well‐designed COF‐Ir not only acts as safety cover to prevent CALB from deactivation but promotes racemization of secondary amines via photo‐induced hydrogen atom transfer (HAT) process. Photoelectric characterization and TDDFT calculation revealed that (ppy)2Ir units in COF‐Ir play crucial role in this photocatalytic system which enhance its photo‐redox properties through facilitating the separation between photoelectrons (e−) and holes (h+). Furthermore, the heterogeneous photoenzymatic nanoreactor could be recycled for five rounds with slight decline of catalytic reactivity. [ABSTRACT FROM AUTHOR]

The article discusses the synthesis of P-chiral tertiary phosphine oxides through copper-catalyzed dynamic kinetic asymmetric C-P cross-coupling. P-stereogenic compounds are important in various fields, but their conventional synthesis methods have limitations. The use of secondary phosphine oxides (SPOs) as an alternative reagent has been explored, but challenges such as racemization and side reactions remain. The authors developed a copper catalyst and optimized reaction conditions to achieve highly enantioselective C-P coupling reactions, resulting in a wide range of P-stereogenic compounds with high yields and enantioselectivities. The resulting compounds can be further transformed into structurally diverse P-chiral scaffolds. The article also highlights the limitations and areas for future research in this field. [Extracted from the article]

Abstract Metal‐enzyme integrated catalysts (MEICs) that combine metal and enzyme offer great potential for sustainable chemoenzymatic cascade catalysis. However, rational design and construction of optimal microenvironments and accessible active sites for metal and enzyme in individual nanostructures are necessary but still challenging. Herein, Pd nanoparticles (NPs) and Candida antarctica lipase B (CALB) are co‐immobilized into the pores and surfaces of covalent organic frameworks (COFs) with tunable functional groups, affording Pd/COF‐X/CALB (X = ONa, OH, OMe) MEICs. This strategy can regulate the microenvironment around Pd NPs and CALB, and their interactions with substrates. As a result, the activity of the COF‐based MEICs in catalyzing dynamic kinetic resolution of primary amines is enhanced and followed COF‐OMe > COF‐OH > COF‐ONa. The experimental and simulation results demonstrated that functional groups of COFs modulated the conformation of CALB, the electronic states of Pd NPs, and the affinity of the integrated catalysts to the substrate, which contributed to the improvement of the catalytic activity of MEICs. Further, the MEICs are prepared using COF with hollow structure as support material, which increased accessible active sites and mass transfer efficiency, thus improving catalytic performance. This work provides a blueprint for rational design and preparation of highly active MEICs.

Axially chiral architectures exist widely in natural products, biologically relevant molecules, chiral ligands and catalysts as well as functional materials. Therefore, catalytic asymmetric synthesis of atropisomers has become one of the most fast‐growing fields in the community of chemistry and rapid advances have occurred. Among different methods reported, the organocatalytic atroposelective dynamic kinetic resolution (DKR) involving ring manipulations stands out as a cutting‐edge technology to construct axial chirality from the point of atom/step economy. In this DKR strategy, the configurational lability of starting materials originates from chirally‐labile ring structure of cyclic substrates/intermediates or transient ring formation through noncovalent interactions from acyclic substrates. The two atropisomers of starting material are in equilibrium in the reaction medium, ensuring the constant transformation of the less reactive atropisomer into the more reactive one, and then to a single enantiopure product in the presence of an appropriate organocatalyst. This review summarizes recent advancements on this topic, including their scopes, limitations, mechanisms, applications and provides some insights into further developments. [ABSTRACT FROM AUTHOR]

We report an enzyme‐catalyzed dynamic kinetic resolution protocol for the one‐pot asymmetric synthesis of substituted purine derivatives. The controllable N‐9/N‐7 substitution, which posed formidable challenges in organic synthesis, could be accomplished by choosing different types of enzymes as catalysts. This method was proved scalable and was used to prepare a series of prodrugs of medicinally active acids. In addition, the recyclability test of the biocatalysts indicated the potential of this strategy for applications in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

We report a strategy for stereoselective O‐aryl‐glycoside synthesis by copper‐catalyzed cross‐coupling of a variety of anomeric sugars and (hetero)aromatic iodides. Stereocontrol of the α/β selectivity can be successfully realized by slight structural modifications of the oxalic diamide ligands. Mechanistic studies indicated a dynamic kinetic resolution (DKR) reaction mechanism controlled by the ligand structures. This reaction could be performed on gram scale, and has also been applied to the synthesis of some natural products. [ABSTRACT FROM AUTHOR]

A highly enantioselective biocatalytic dynamic kinetic resolution (DKR) of 2‐(quinoline‐8‐yl) 3‐methylbenzaldehydes and 1‐naphthaldehydes is described. The reaction proceeds by atroposelective carbonyl reduction catalyzed by commercial ketoreductases (KREDs), generally reaching high conversions and excellent enantiomeric excesses. Both atropoisomers of the final alcohols can be obtained by a proper selection of the biocatalyst. The DKR strategy relies in the racemization of the stereogenic axis that takes place thanks to a transient Lewis acid‐base interaction (LABI) between the nitrogen in the quinoline and the carbonyl group. [ABSTRACT FROM AUTHOR]

N-heterocyclic carbene-catalyzed enantioselective kinetic resolutions, dynamic kinetic resolutions, and desymmetrization reactions are systematically reviewed. The content is organized according to the activation modes involved in these transformations. Future advances within this highly active research field are discussed from our perspectives on the topic. [ABSTRACT FROM AUTHOR]

Sulfoxides are widely used in the pharmaceutical industry and as ligands in asymmetric catalysis. However, the efficient asymmetric synthesis of this structural motif remains limited. In this study, we disclosed a Ni‐catalyzed enantioconvergent reaction that utilizes both racemic allenyl carbonates and β‐sulfinyl esters. Our method employs cheap and more sustainable Ni(II) as a precatalyst and successfully overcomes the challenging poisoning effect and instability of sulfenate generated in situ. This enables the synthesis of a series of dienyl sulfoxides with enantioselectivity of up to 98 % ee. The product exhibits tremendous potential in various applications, including diastereoselective Diels–Alder reactions, coordination with transition metals, and incorporation into medicinal compounds, among others. Using a combination of experimental and computational methods, we have uncovered an interesting associated outersphere mechanism that contrasts with conventional mechanisms commonly observed in asymmetric transition metal catalysis. [ABSTRACT FROM AUTHOR]

Planar‐chiral cyclophanes have received increasing attention for drug discovery and catalyst design. However, the catalytically asymmetric synthesis of planar‐chiral cyclophanes has been a longstanding challenge. We describe the first Pd(II)‐catalyzed enantioselective C−H olefination of prochiral cyclophanes. The low rotational barrier of less hindered benzene ring in the substrates allows the reaction to proceed through a dynamic kinetic resolution. This approach exhibits broad substrate scope, providing the planar‐chiral cyclophanes in high yields (up to 99 %) with excellent enantioselectivities (up to >99 % ee). The ansa chain length scope studies reveal that the chirality of the cyclophanes arises from the bond rotation constraint of the benzene ring around the macrocycle plane, rather than the C−N axis. The C−H activation approach is also applicable to the late‐stage modification of bioactive molecules and pharmaceuticals. [ABSTRACT FROM AUTHOR]

Rhodium‐catalyzed enantioselective hydroacylation of racemic alkynals having a substituent at the α‐position of the carbonyl group is described. This reaction can be applied for the wide range of substrates (22 examples), and mechanistic studies revealed that a dynamic kinetic resolution (DKR) process occurs during the hydroacylation, giving various cyclic ketones in 47–93% yields with 59:41 to 97:3 er from racemic starting materials. [ABSTRACT FROM AUTHOR]

The first total synthesis of (−)‐salinosporamide D was achieved using d‐serine as the sole chiral source. This approach stands out for its application of the principles of memory of chirality and dynamic kinetic resolution in the intramolecular aldol reaction of serine‐derived oxazolidines. These strategies enabled the rapid construction of a pyrrolidinone core and installation of contiguous stereocenters. The key intermediate was readily obtained, culminating the asymmetric total synthesis of salinosporamide D. The total synthesis of salinosporamides A and I was also achieved using the same chemistry. [ABSTRACT FROM AUTHOR]

Asymmetric cross‐couplings based on 1,2‐carbon migration from B‐ate complexes have been developed efficiently to access valuable organoboronates. However, enantioselective reactions triggered by 1,2‐boron shift have remained to be unaddressed synthetic challenge. Here, Ir‐catalyzed asymmetric allylic alkylation enabled by 1,2‐boron shift was developed. In this reaction, we disclosed that excellent enantioselectivities were achieved through an interesting dynamic kinetic resolution (DKR) process of allylic carbonates at the elevated temperature. Notably, the highly valuable (bis‐boryl)alkenes have enabled an array of diversifications to access versatile molecules. Extensive experimental and computational studies were conducted to elucidate the reaction mechanism of DKR process and clarify the origin of excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

A novel and sustainable tandem‐catalysis system for asymmetric synthesis is disclosed, which is fabricated by bio‐inspired self‐assembly of artificial arthropod exoskeletons (AAEs) or artificial fungi cell walls (AFCWs) containing two different types of catalysts (enzyme and metal nanoparticles). The heterogeneous integrated enzyme/metal nanoparticle AAE/AFCW systems, which contain chitosan as the main structural component, co‐catalyze dynamic kinetic resolution of primary amines via a tandem racemization/enantioselective amidation reaction process to give the corresponding amides in high yields and excellent ee. The heterogeneous AAE/AFCW systems display successful heterogeneous synergistic catalysis at the surfaces since they can catalyze multiple reaction cycles without metal leaching. The use of natural‐based and biocompatible structural components makes the AAE/AFCW systems fully biodegradable and renewable, thus fulfilling important green chemistry requirements. [ABSTRACT FROM AUTHOR]

Chiral β‐aryl propanamine is an important structure unit of bioactive molecules or drugs. But its efficient synthesis remains a challenging task. In this study, several enantiocomplementary imine reductases capable of dynamic kinetic resolution‐reductive amination of sixteen 2‐phenylpropanal derivatives of diverse structural characteristics with four different amines were identified through screening 196 imine reductases. Furthermore, (S)‐IR60, (R)‐IR74 and (R)‐IR207 were applied to access a series of different β‐aryl propanamines with excellent ee values (90 to 99 %) and high isolated yields (36 to 79 %), and two of them were further transformed into 3‐methylindolines through intramolecular Buchwald‐Hartwig cross‐coupling and deallylation, providing an effective method to construct this class of pharmaceutically important compounds. [ABSTRACT FROM AUTHOR]

Herein, we present a chiral boro‐phosphate catalyzed atroposelective asymmetric transfer hydrogenation method, leading to a family of axially chiral styrene‐type allylalcohols. This dynamic kinetic resolution approach portrays simple procedure, mild conditions and good enantiocontrol (51–95% ee), thus providing an important alternative to assemble the challenging atropisomeric aryl‐acyclic alkene scaffolds. [ABSTRACT FROM AUTHOR]

An unprecedent asymmetric catalytic benzilic amide rearrangement for the synthesis of α,α‐disubstituted piperazinones is reported. The reaction proceeds via a domino [4+1] imidazolidination/formal 1,2‐nitrogen shift/1,2‐aryl or alkyl migration sequence, employing readily available vicinal tricarbonyl compounds and 1,2‐diamines as starting materials. This approach provides an efficient access to chiral C3‐disubsituted piperazin‐2‐ones with high enantiocontrol, which are exceedingly difficult to access from the existing synthetic methodologies. The observed enantioselectivity was proposed to be controlled by dynamic kinetic resolution in the 1,2‐aryl/alkyl migration step. The resulting densely functionalized products are versatile building blocks to bioactive natural products, drug molecules and their analogues. [ABSTRACT FROM AUTHOR]

Diaryl ethers are widespread in biologically active compounds, ligands and catalysts. It is known that the diaryl ether skeleton may exhibit atropisomerism when both aryl rings are unsymmetrically substituted with bulky groups. Despite recent advances, only very few catalytic asymmetric methods have been developed to construct such axially chiral compounds. We describe herein a dynamic kinetic resolution approach to axially chiral diaryl ethers via a Brønsted acid catalyzed atroposelective transfer hydrogenation (ATH) reaction of dicarbaldehydes with anilines. The desired diaryl ethers could be obtained in moderate to good chemical yields (up to 79 %) and high enantioselectivities (up to 95 % ee) under standard reaction conditions. Such structural motifs are interesting precursors for further transformations and may have potential applications in the synthesis of chiral ligands or catalysts. [ABSTRACT FROM AUTHOR]

New types of one‐pot multi‐step enzymatic cascade transformation involving dynamic kinetic resolution to convert racemic substrates to chiral products in high ee and yield were developed. Unique cascade reactions of easily accessible racemic trans‐β‐methyl or α‐methyl epoxides to produce (S)‐2‐arylpropionic acids, (R)‐ and (S)‐2‐arylpropyl amines were demonstrated via styrene oxide isomerase (SOI)‐catalyzed Meinwald epoxide rearrangement to generate 2‐arylpropanal in situ, which was followed by spontaneous racemization, and alcohol dehydrogenase (ADH)‐catalyzed (S)‐enantioselective oxidation or transaminase (TA)‐catalyzed (R)‐ or (S)‐enantioselective amination, respectively. Cascade reactions performed with isolated enzymes or whole‐cell biocatalysts produced pharmaceutically relevant (S)‐2‐arylpropionic acids, (R)‐ and (S)‐2‐arylpropyl amines with high enantioselectivity and yield. The cascades starting with in situ aldehyde generation from epoxides effectively minimized side reactions related to aldehyde instability and displayed a wide substrate scope. [ABSTRACT FROM AUTHOR]

We report a dynamic kinetic resolution (DKR) of chiral 4-pentenals by olefin hydroacylation. A primary amine racemizes the aldehyde substrate via enamine formation and hydrolysis. Then, a cationic rhodium catalyst promotes hydroacylation to generate α,γ-disubstituted cyclopentanones with high enantio- and diastereoselectivities.

Strategies on the construction of enantiomerically pure silicon‐stereogenic silanes generally relies on desymmetrization of prochiral and symmetric substrates. However, dynamic kinetic asymmetric transformations of organosilicon compounds have remained underdeveloped and unforeseen owing to a lack of an effective method for deracemization of the static silicon stereocenters. Here we report the first Rh‐catalyzed dynamic kinetic asymmetric intramolecular hydrosilylation (DyKAH) with "silicon‐centered" racemic hydrosilanes that enables the facile preparation of silicon‐stereogenic benzosiloles in good yields and excellent enantioselectivities. The special rhodium catalyst controlled by non‐diastereopure‐type mixed phosphine‐phosphoramidite ligand with axial chirality and multiple stereocenters can induce enantioselectivity efficiently in this novel DyKAH reaction. Density functional theory (DFT) calculations suggest that the amide moiety in chiral ligand plays important role in facilitating the SN2 substitution of chloride ion to realize the chiral inversion of silicon center. [ABSTRACT FROM AUTHOR]

A highly efficient enantioselective construction of heterobiaryl N-oxides was developed. A series of axially chiral heterobiaryl N-oxides were generated via the cascade reaction of aminobenzamides with heterobiaryl aldehydes in the presence of chiral phosphoric acids. A number of atropisomers were afforded in moderate to good yields with excellent enantioselectivities and diastereoselectivities. Preliminary results demonstrate that the heterobiaryl N-oxides can be utilized as efficient chiral ligands in asymmetric catalysis. [ABSTRACT FROM AUTHOR]

Kinetic resolution is one of the most common methods to access enantiomerically enriched compounds. In this method, the resolution is based on the existing difference in reaction rates of the two enantiomers with a chiral catalyst. In the dynamic kinetic resolution, the less reactive enantiomer is racemized and the racemic mixture is further resolved, leading eventually to complete transformation to an enantioenriched compound. This review summarizes the dual catalytic strategies (i. e. modular combinations of distinct catalysts) that have been applied to kinetic resolution and dynamic kinetic resolution. We focus upon the role of the two catalysts, the compatibility between them, and the practical benefits. [ABSTRACT FROM AUTHOR]

Dynamic kinetic resolution allows for the synthesis of enantiomerically pure asymmetric alcohols. Cyclopentadienyl-derived ruthenium catalysts were immobilized with an ionic liquid, [BMIM][NTf2], on multiwall carbon nanotubes and used for the racemization of chiral secondary alcohols. This successful approach was combined with the enantioselective enzymatic acylation of secondary alcohols (1-phenylethanol and 1-(1-naphthyl)ethanol) using Novozyme® 435. The resulting catalytic system of the ruthenium racemization catalysts and enzymatic acylation led to chiral esters being obtained by dynamic kinetic resolution. The immobilized catalytic system in the ionic liquid gave the same activity of >96% yield within 6 h and a selectivity of 99% enantiomeric excess as the homogeneous system, while allowing for the convenient separation of the desired products from the catalyst. Additionally, the process can be regarded as green, since the efficient reuse of the catalytic system was demonstrated. [ABSTRACT FROM AUTHOR]

Natural lipases typically recognize enantiomers of alcohols based on the size differences of substituents near the carbinol moiety and selectively react with the R enantiomers of secondary alcohols. Therefore, lipase‐catalyzed dynamic kinetic resolution (DKR) of racemic secondary alcohols produces only R enantiomers. We report herein a method for obtaining S enantiomers by DKR of secondary 3‐(trialkylsilyl)propargyl alcohols by using a well‐known R‐selective Pseudomonas fluorescens lipase in combination with a racemization catalyst VMPS4, in which the silyl group reverses the size relationship of substituents near the carbinol moiety. We have already reported R‐selective DKR of the corresponding propargyl alcohols without substituents on the ethynyl terminal carbon, and the presence of an easily removable silyl group has enabled us to produce both enantiomers of propargyl alcohols in high chemical yields and with high enantiomeric excess. In addition, immobilization of the lipase on Celite was found to be important for achieving a high efficiency of the DKR. [ABSTRACT FROM AUTHOR]

Catalytic asymmetric dynamic kinetic resolution of configurationally labile bridged biaryls is emerging as a powerful strategy for atropisomer synthesis. However, the reported examples suffer from an inherent challenge as the reactivity is highly dependent on the torsional strain of the biaryl substrates, which significantly narrows down the scope and hampers the application. Herein, we report our discovery and development of a torsional strain‐independent reaction between biaryl thionolactones and activated isocyanides. By employing auto‐tandem silver catalysis, a universal synthesis of both tri‐ and tetra‐ortho‐substituted thiazole‐containing biaryls was realized in high yields with high enantioselectivities. In addition, these products could be facilely converted to a novel type of bridged biaryls bearing an eight‐membered lactone. Mechanistic studies were carried out to elucidate the cause of this unusual torsional strain‐independent reactivity. [ABSTRACT FROM AUTHOR]

A general Rh-catalyzed addition reaction of nitrogen containing heterocycles to internal allenes is reported. Starting from racemic internal allenes a dynamic kinetic resolution (DKR) provides N-allylated triazoles and tetrazoles. Simultaneous control of N1/Nx-position selectivity, enantioselectivity and olefin geometry gives access to important building blocks of target-oriented synthesis. The synthetic utility is demonstrated by a gram-scale reaction and a broad substrate scope tolerating multiple functional groups. Deuterium labeling experiments and experiments with enantioenriched allenes as starting material support a plausible reaction mechanism. [ABSTRACT FROM AUTHOR]

A dual immobilized lipase and oxovanadium co-catalyzed dynamic kinetic resolution (DKR) system was established and successfully applied to synthesize (R)-1-(3-Methoxyphenyl) acetate in batch, resulting in a key chiral intermediate of (S)-rivastigmine with highly yield (97.6 %), e.e (99.01 %) and selectivity Sel (99.4 %). Herein, oxovanadium was immobilized onto diatomite via grinding immobilization for the first time to access a novel immobilized oxovanadium (V-D) used to catalyze an in situ racemization of undesired enantiomer substrate. The racemization rate of hydrated vanadyl sulfate was found for the first time to be much higher than that of vanadyl sulfate without crystalline water because water molecules in the former may form ion clusters of solvation membranes to disperses the charge density of positive carbon ions and promote their stability. This grinding immobilization approach may become a promising alternative for the immobilization of metals, especially precious metals due to its low cost, high efficiency, easily separated and large reaction interface. The kinetic model of the kinetic resolution catalyzed by LA-MR was developed, which may obey the sequential mechanism with both substrate and product inhibition, while the in-situ racemization reaction catalyzed by V-D may comply with power law. • A novel dual immobilized lipase and oxovanadium co-catalyzed DKR system. • The grinding immobilization of oxovanadium onto diatomite was first employed. • The enzymatic kinetic resolution may obey the sequential mechanism. • The yield, e.e and selectivity Sel are greater than 99 % in continuous flow DKR. [ABSTRACT FROM AUTHOR]

The conversion of rac-phenylglycinonitrile by different variants of the nitrilase from Pseudomonas fluorescens EBC191 (EC 3.5.5.1) was studied and the amounts and chiral composition of the formed phenylglycine and phenylglycine amide compared. Muteins that converted rac-phenylglycinonitrile to extraordinarily high amounts of phenylglycine or phenylglycine amide were tested for the chemoenzymatic enantioselective one-pot synthesis of (R)- and (S)- phenylglycine and (R)- and (S)-phenylglycine amide. The chemoenzymatic synthesis combined the initial step in the traditional chemical Strecker synthesis which results in the formation of rac-phenylglycinonitrile from benzaldehyde, cyanide, and ammonia with the enzymatic conversion of the formed nitrile by the nitrilase variants. The aminonitrile synthesis was optimized in order to obtain conditionswhich allowed under mildly alkaline conditions (pH 9.5)maximal yields of phenylglycinonitrile and the in-situ racemization of the compound. The racemic phenylglycinonitrile was directly converted under the alkaline conditions without any interposed purification step by cells of Escherichia coli overexpressing recombinant nitrilase variants. The application of a mutant of E. coli defect in a (S)-phenylglycine amide hydrolysing peptidase (E. coli JM109ΔpepA) expressing a highly reaction- and (R)-specific nitrilase variant allowed the synthesis of (R)- phenylglycine with ee-values ≥ 95% in yields up to 81% in relation to the initially added benzaldehyde. These yields indicated a dynamic kinetic resolution which involved the racemization of (S)- to (R)-phenylglycinonitrile under the used alkaline conditions with the concurrent hydrolysis of (R)-phenylglycinonitrile to (R)- phenylglycine. The addition of resting cells of E. coli JM109ΔpepA synthesizing an amide forming nitrilase variant to the final product of the Strecker synthesis and/or using E. coli strains with an intact aminopeptidase gene resulted in the preferred formation of (S)-phenylglycine amide, (R)-phenylglycine amide or (S)-phenylglycine. [ABSTRACT FROM AUTHOR]

Chiral β‐hydroxysulfides are an important class of organic compounds which find broad application in organic and pharmaceutical chemistry. Herein we describe the development of novel biocatalytic and chemoenzymatic methods for the enantioselective synthesis of β‐hydroxysulfides by exploiting ketoreductase (KRED) enzymes. Four KREDs were discovered from a pool of 384 enzymes identified and isolated through a metagenomic approach. KRED311 and KRED349 catalysed the synthesis of β‐hydroxysulfides bearing a stereocentre at the C−O bond with opposite absolute configurations and excellent ee values by novel chemoenzymatic and biocatalytic‐chemical‐biocatalytic (bio‐chem‐bio) cascades starting from commercially available thiophenols/thiols and α‐haloketones/alcohols. KRED253 and KRED384 catalysed the enantioselective synthesis of β‐hydroxysulfides bearing a stereocentre at the C−S bond with opposite enantioselectivities by dynamic kinetic resolution (DKR) of racemic α‐thioaldehydes. [ABSTRACT FROM AUTHOR]

Tofacitinib is an oral protein tyrosine kinase inhibitor approved for the treatment of rheumatoid arthritis, active psoriatic arthritis and ulcerative colitis. Its efficient production remains a challenge due to the two consecutive stereogenic centers associated to the piperidine ring. In this study, an enzymatic dynamic kinetic resolution‐asymmetric reductive amination was developed to prepare enantiomerically complementary cis‐1‐benzyl‐N,4‐ dimethylpiperidin‐3‐amine and its analogues. Two enantiocomplementary imine reductases (IREDs) were identified for the synthesis of (3R,4R)‐ and (3S,4S)‐1‐benzyl‐N,4‐dimethylpiperidin‐3‐amine in high isolated yields (83% and 91%) with excellent stereoselectivity (97% and >99% ee values) and diastereoselectivity (>99:1 dr), providing a green methodology for the production of the key intermediate of tofacitinib. [ABSTRACT FROM AUTHOR]

An unprecedented Cinchona alkaloid catalyzed atropoenantioselective transamination of biaryl aldehydes with 2,2-diphenylglycine via a cascade decarboxylation and dynamic kinetic resolution strategy is described. This protocol features broad substrate scope and good functional group tolerance and allows the rapid assembly of axially chiral biaryls in high yields with acceptable to good enantioselectivities. In addition, such structural motifs may have potential applications in enantioselective catalysis as chiral ligands or catalysts. [ABSTRACT FROM AUTHOR]

As a novel type of macrocycles with attractive planar chirality, pillar[5]arenes have gained increasing research interest over the past decades, enabling their widespread applications in diverse fields such as porous materials, molecular machines, and chiral luminescence materials. However, the catalytic methodology towards the enantioselective synthesis of planar chiral pillar[5]arenes remains elusive. Here we report a novel method for the enantioselective synthesis of planar chiral pillar[5]arenes via asymmetric Sonogashira coupling, giving access to a wide range of highly functionalized planar chiral pillar[5]arenes, including both homo- and hetero-rimmed ones, with excellent enantioselectivities. Attractively, the resultant planar chiral pillar[5]arenes show great potential for widespread use in many areas such as chiral luminescent materials. This work not only enables the successful synthesis of planar chiral pillar[5]arenes with abundant structural and functional diversity as key building blocks for practical applications but also enriches the asymmetric cross-coupling methodologies in organic synthetic chemistry., (© 2024 Wiley‐VCH GmbH.)

A ruthenium-catalyzed reductive amination via asymmetric transfer hydrogenation (ATH) has been used to perform an efficient dynamic kinetic resolution (DKR) of N-aryl 2-formyl pyrroles decorated with a phosphine moiety positioned at the ortho' position. The strategy relies on the labilization of the stereogenic axis in the substrate facilitated by a transient Lewis acid-base interaction (LABI) between the carbonyl carbon and the phosphorus center. The reaction features broad substrate scope of aliphatic amines and N-aryl pyrrole scaffolds, and proceeds under very mild conditions to afford P,N atropisomers in good to high yields and excellent enantioselectivities (up to 99 % ee) for both diphenyl and dicyclohexylphosphino derivatives., (© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The conceptual merger of relay catalysis with dynamic kinetic resolution strategy is reported to enable regio- and enantioselective C(sp 3 )-H bond arylation of aliphatic alcohols, forming enantioenriched β-aryl alcohols typically with >90 : 10 enantiomeric ratios (up to 98 : 2 er) and 36-74 % yields. The starting materials bearing neighbouring stereogenic centres can be converted to either diastereomer of the β-aryl alcohol products, with >85 : 15 diastereomeric ratios determined by the catalysts. The reactions occur under mild conditions, ensuring broad compatibility, and involve readily available aryl bromides, an inorganic base, and commercial Ru- and Pd-complexes. Mechanistic experiments support the envisioned mechanism of the transformation occurring through a network of regio- and stereoselective processes operated by a coherent Ru/Pd-dual catalytic system., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)