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The development of sustainable, functional-group-tolerant catalysis is highly significant from the perspectives of safety, user-friendliness, and cost-effectiveness. We report herein the triple hydrogen-bonding donor activator N -triflyl phosphoric triamide (N -TPT ) for the synergistic Brønsted acid aquacatalysis of multicomponent allylation 'on-water'. The reaction demonstrated remarkable efficiency in converting polar diol substrate, such as 1,3-dihydroxyacetone, into α-tertiary amine derivative incorporating homoallylic amine functionalities using bulk water as the reaction medium. The single crystal X-ray structure and control experiments highlighted the crucial role of multiple hydrogen bonds in enabling this aqueous reaction. [ABSTRACT FROM AUTHOR]

Two new mono‐thiourea, four bis‐thiourea and one squaramide organocatalysts were synthesised from L‐tartaric acid. These organocatalysts were able to activate glycosyl phosphates for stereoselective nucleophilic substitution reactions with broad functional group compatibility under mild conditions. The influence of the number and position of the thiourea groups and the proximity of the asymmetric centre to the catalytic important atoms for the stereoselective outcome of the glycosylation reactions was studied. 1,2‐cis Glycosides were obtained in up to 85 % yield and high diastereoselectivity (up to α:β 83 : 17). [ABSTRACT FROM AUTHOR]

A new family of IAN‐type amine N‐oxides is presented as catalysts for the allylation and crotylation of aromatic aldehydes with allyltrichlorosilanes. These reaction exhibit a remarkably positive nonlinear effect which enables utilization of the catalysts in subenantiopure form. As enantiopure catalysts are not required under this regime, the synthesis of these N‐oxides is straightforward through catalytic asymmetric synthesis, avoiding lenghty synthesis from the chiral pool or resolution of diastereoisomers. Studies of the corresponding crotylation with Z‐ and E‐crotylsilanes suggest that the reaction proceeds through a chair‐like transition state. [ABSTRACT FROM AUTHOR]

An unprecedented chemodivergent strategy for parallel kinetic resolution (PKR) is disclosed through which two planar chiral products bearing different structures were simultaneously afforded with opposite stereoselectivities. Two achiral esters are activated by one single chiral N‐heterocyclic carbene (NHC) catalyst to react with the different enantiomers of the racemic imine substrate in a parallel fashion. Two products bearing distinct structures and opposite stereoselectivities are respectively afforded from the same reaction system in good to excellent yields, enantio‐ and diastereoselectivities. Control experiments and kinetic studies are carried out to probe the kinetic and dynamic properties during the reaction progress. The planar chiral pyridine and lactam products show interesting applications in both asymmetric synthesis and pesticide development. [ABSTRACT FROM AUTHOR]

The recent development of photoredox and energy transfer catalysis has led to a significant expansion of visible‐light‐driven chemical transformations. These methods have demonstrated exceptional efficiency in converting a wide range of substrates into radical intermediates and generating open‐shell catalytic species. However, the simplification of catalytic systems and the direct generation of highly reactive radical organocatalysts through direct visible‐light irradiation from stable precatalysts remains largely an unrealized goal. This challenge is mainly due to the limited availability of precatalysts that are responsive to visible light. Herein, we introduce a new class of bench‐stable dicationic disulfuranes, which release highly reactive thiyl radicals upon blue‐light excitation. Spectroscopic and computational studies reveal that this reactivity arises from a combination of structural features and intermolecular interactions. This family of molecules has been employed to catalyze radical cascades previously incompatible with photoredox conditions, enabling the efficient formation of 1,2‐dioxolanes and 1,3‐hydroxyketones in excellent yields and short reaction times. [ABSTRACT FROM AUTHOR]

The field of asymmetric organocatalysis has witnessed significant advancements in recent years, with chiral urea and thioureas emerging as powerful catalysts. In this study, we aimed to design novel polyurea‐polyurethane nanocomposites functionalized with cinchona urea groups, incorporating organoclay and graphene oxide, to serve as heterogeneous organocatalysts in asymmetric synthesis. The synthesis of these polyurea‐polyurethane nanocomposites was achieved through a two‐component polycondensation reaction. The resulting chiral polyurea‐polyurethanes (PU‐PURs) exhibited favorable yields and demonstrated precise control over stereochemistry, resulting in high enantioselectivity. The incorporation of nanocomposites, such as CU‐MMT and graphene oxide (GO), significantly enhanced the catalytic performance of the PU‐PURs. The CU‐MMT nanocomposites exhibited higher catalytic activity, while the PU‐PURs/GO still exhibited enantioselectivity greater than 99 %. Overall, this study highlights the potential of these novel polyurea‐polyurethane nanocomposites as efficient and versatile heterogeneous organocatalysts in asymmetric synthesis. [ABSTRACT FROM AUTHOR]

Polythioesters (PTEs) are emerging sustainable polymers for their degradability and recyclability. However, low polymerizability of monomers and extensive side reactions often hampered the polymerization process. Moreover, copolymers containing both thioester and other types of functional groups in the backbone are highly desirable but rarely accomplished owing to several synthetic challenges. Here, we report the ring‐opening cascade polymerization (ROCAP) of N‐(2‐(acetylthio)ethyl)‐glycine N‐carboxyanhydrides (TE‐NCA) to afford recyclable PTEs and unprecedented poly(thioester‐co‐peptoid)s (P(TE‐co‐PP)s) in a controlled manner. By developing appropriated carboxylic acid‐tertiary amine dual catalysts, intramolecular S‐to‐N acyl shift is coupled into the ROCAP process of TE‐NCA to yield products with dispersity below 1.10, molecular weight (Mn) up to 84.5 kDa, and precisely controlled ratio of thioester to peptoids. Random copolymerization of sarcosine NCA (Sar‐NCA) and TE‐NCA gives thioester‐embedded polysarcosine with facile backbone degradation while maintaining the water solubility. This work represents a paradigm shift for the ROP of NCAs, enriches the realm of cascade polymerizations, and provides a powerful synthetic approach to functional PTEs and P(TE‐co‐PP)s that are otherwise difficult or impossible to make. [ABSTRACT FROM AUTHOR]

As a significant variant of the Michael reaction, the 1,6‐addition reaction has undergone considerable development over the past decade. This effective strategy enables the synthesis of a variety of novel and potentially bioactive functional molecules. In this review, we summarize the recent progress in NHC‐catalyzed 1,6‐addition reactions, highlighting their efficiency in the rapid synthesis of complex functional molecules. We also provide our perspectives on the future development of this dynamic and highly active research area. [ABSTRACT FROM AUTHOR]

This report outlines the evolution and recent progress about the different protocols to synthesize the N‐heterocycles fused hybrids, specifically [1,2,3]triazolo[1,5‐a]quinoline. This review encompasses a broad range of approaches, describing several reactions for obtaining this since, such as dehydrogenative cyclization, oxidative N−N coupling, Dieckmann condensation, intramolecular Heck, (3+2)‐cycloaddition, Ullman‐type coupling and direct intramolecular arylation reactions. We divided this review in three section based in the starting materials to synthesize the target [1,2,3]triazolo[1,5‐a]quinolines. Starting materials containing quinoline or triazole units previously formed, as well as starting materials which both quinoline and triazole units are formed in situ. Different methods of obtaining are described, such as metal‐free or catalyzed conditions, azide‐free, using conventional heating or alternative energy sources, such as electrochemical and photochemical methods. Mechanistic insights underlying the reported reactions were also described in this comprehensive review. [ABSTRACT FROM AUTHOR]

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A new protocol for the synthesis of 2‐amino‐substituted 1,3,4‐oxadiazoles and 1,3,4‐thiadiazoles, were developed using semicarbazide or thiosemicarbazide along with the various aldehydes, followed by C−X (X=O, S) bond formation using ascorbic acid as a catalyst. This rapid, efficient, accessible, and robust/scalable sequential synthesis works with aromatic, aliphatic, and cinnamic aldehydes to provide a wide range of diazole derivatives with a 2‐amino substituent without the use of any transition metals. The synthesised molecules were characterised by 1H and 13C NMR analysis. [ABSTRACT FROM AUTHOR]

In an attempt to create models of phosphodiesterases, we previously investigated bis(guanidinium) naphthols. Such metal‐free anion receptors cleaved aryl phosphates and also plasmid DNA. Observed reaction rates, however, could not compete with those of highly reactive metal complexes. In the present study, we have replaced the guanidines by ethylene diamine side chains which accelerates the plasmid cleavage by compound 13 significantly (1 mM 13: t1/2=22 h). Further gains in reactivity are achieved by azo coupling of the naphthol unit. The electron accepting azo group decreases the pKa of the hydroxy group. It can also serve as a dye label and a handle for attaching DNA binding moieties. The resulting azo naphthol 17 not only nicks (1 mM 17: t1/2~1 h) but also linearizes pUC19 DNA. Although the high reactivity of 17 seems to result in part from aggregation, in the presence of EDTA azo naphthol 17 obeys first order kinetics (1 mM 17: t1/2=4.8 h), reacts four times faster than naphthol 13 and surpasses by far the former bis(guanidinium) naphthols 4 and 5. [ABSTRACT FROM AUTHOR]

Phthalimide‐N‐oxyl radicals (PINO) are catalytically active hydrogen abstracting species generated from N‐hydroxyphthalimide (NHPI) – one of the most efficient and widely used organocatalysts for free‐radical oxidative CH‐functionalization processes. The self‐decay of PINO is one of the main limiting factors of NHPI usage, but currently there is no consensus on the mechanism of this important process. In the present work, quantitative EPR and NMR monitoring of PINO generation and degradation along with decay product analysis and control experiments allowed us to build a consistent picture of PINO decay chemistry and put together previously contradictory results. PINO yields achievable employing various oxidants were measured and compared for the first time. At least two PINO decay pathways were revealed: "trimerization" (with partial fragmentation, favored by high PINO concentrations at initial stage of decay), and medium oxidation favored by low PINO concentrations. The main PINO decomposition product, the "trimer" can easily be recycled back to NHPI. [ABSTRACT FROM AUTHOR]

The umpolung of aldimines using N‐heterocyclic carbenes (NHCs) is less explored compared to the established polarity reversal of aldehydes. Described herein is an NHC‐catalyzed imine umpolung /6π‐electrocyclization cascade, which leads to the atom‐ and pot‐economic synthesis of biologically important dihydrochromeno indoles. For the first time, the nucleophilic aza‐Breslow intermediates have been intercepted with unactivated alkynes. Preliminary mechanistic and DFT studies shed light on the role of the phenolic −OH moiety in promoting the addition of the aza‐Breslow intermediate to the unactivated alkyne via an intramolecular proton transfer in a stepwise manner. DFT studies also support the regioselectivity preference for the 5‐exo‐dig cyclization pathway, leading to the exclusive formation of the indole products. Moreover, a comparison of Gibbs free energies provides insight into a thermodynamically preferred 6π‐electrocyclization over a competing oxa‐Michael pathway. Further, this strategy is applied to the formal synthesis of a Hepatitis C Virus (HCV) NS5A inhibitor in a step‐economical method. [ABSTRACT FROM AUTHOR]

Catalytic enantioselective preparation of alkene atropisomers with multiple stereogenic elements and discovery of their applications have become significant but challenging issues in the scientific community due to the unique structures of this class of atropisomers. We herein report the first catalytic atroposelective preparation of cyclopentenyl[b]indoles, a new kind of alkene atropisomers, with stereogenic point and axial chirality via an unusual rearrangement reaction of 3‐indolylmethanols under asymmetric organocatalysis. Notably, this novel type of alkene atropisomers have promising applications in developing chiral ligands or organocatalysts, discovering antitumor drug candidates and fluorescence imaging materials. Moreover, the theoretical calculations have elucidated the possible reaction mechanism and the non‐covalent interactions to control the enantioselectivity. This approach offers a new synthetic strategy for alkene atropisomers with multiple stereogenic elements, and represents the first catalytic enantioselective rearrangement reaction of 3‐indolylmethanols, which will advance the chemistry of atropisomers and chiral indole chemistry. [ABSTRACT FROM AUTHOR]

The substituted tetrahydrofuran core is a structural motif in many biologically active and natural compounds. However, the scarcity of enantioselective methods developed towards its synthesis makes this field challenging and attractive to explore. Herein, the first Brønsted‐base catalyzed enantioselective (3+2) annulation of donor‐acceptor cyclopropanes with aldehydes and ketones affording enantioenriched 2,3,5‐substituted tetrahydrofurans is reported. The reaction concept is based on activation of racemic β‐cyclopropyl ketones by a chiral bifunctional Brønsted base which catalyzes the (3+2) annulation for a range of aldehydes and ketones. For aldehydes, the annulation furnished tetrahydrofurans in excellent yield, good diastereoselectivity and with excellent enantioselectivity up to >99 % ee. Surprisingly, aromatic aldehydes afforded the cis‐2,5‐substituted tetrahydrofurans as the major diastereoisomer, while for aliphatic aldehydes the trans‐cycloadduct was favored. The reaction also proceeds well for ketones affording spiro tetrahydrofurans in excellent yields and enantioselectivities (up to 99 % ee). Hammett studies have been conducted to elucidate the influence of the electronic nature of benzaldehydes on the stereoselectivity. Based on the diastereochemical outcome for the aldehydes, two reaction paths for aromatic and aliphatic aldehydes are proposed. Finally, two diastereoselective synthetic transformations have been conducted to demonstrate the synthetic potential of the obtained products. [ABSTRACT FROM AUTHOR]

AbstractHerein, we report a novel method for highly efficient and stereoselective construction of bioactive 2-amino-2-deoxy-1,3-dithioglucosides as N-acetyl muramyl dipeptide analogues via organocatalyzed relay reactions with 3-O-acetyl-2-nitroglucal as the glycosyl donor. The method enjoys mild reaction conditions, efficient one-pot relay reaction, good to excellent yield, and broad substrate scope. [ABSTRACT FROM AUTHOR]

Asymmetric synthesis of derivatives of spiro[indoline‐3,4‐pyrrolo[3,4‐b]pyridines] were first developed through the organocatalytic cascade of Knoevenagel/Michael/cyclization reactions using a quinidine‐derived squaramide. Under the optimized conditions, the three‐component reactions of isatins, cyanoacetates, and 3‐aminomaleimides yield the desired heterocycle‐fused spirooxindoles in good yields (78–91 %) with 53 %–99 % enantiomeric excess (ee). Notably, this reaction enables a broad substrate scope under mild conditions and provides a convenient method for the enantioselective construction of diverse spirooxindoles combined with dihydropyridine and maleimide skeletons, which has great potential for the construction of new bioactive chemical entities. [ABSTRACT FROM AUTHOR]

Fluorine‐containing compounds are important in medicine or crop‐protection. Herein, we show asymmetric organocatalytic Michael/oxa‐Michael cascade leading to chiral fluorinated pyrans under mechanochemical conditions. Formal oxa‐Diels‐Alder reaction between fluorine containing unsaturated keto esters and β,γ‐unsaturated ketones afforded a range of drug‐like pyran derivatives in short times and good to high yields. Ball‐milling conveys the reaction in short times and high product yields, while keeping high enantiomeric purities of products. The reaction is diastereodivergent depending on the use of either monofunctional amine catalysts or bifunctional thiourea or squaramide. [ABSTRACT FROM AUTHOR]

The integration of organocatalysis and enzyme catalysis in one‐pot cascade processes allows for the efficient construction of complex molecular architectures with high levels of stereocontrol. However, challenges related to reaction compatibility between both processes are often a limitation for the development of efficient synthetic routes. In this study, we describe the combination of an enzymatic aerobic oxidation followed by the squaramide‐mediated asymmetric formation of C−P and C−C bonds to access important building blocks such as chiral α‐hydroxyphosphonates and β‐nitro alcohols in good yields and enantiomeric ratios. This sequential process is conducted in a one‐pot fashion within a biphasic system and represents a pioneering example of a chemoenzymatic cascade involving aerobic biooxidation and an organocatalytic step operating under hydrogen‐bond activation mode and under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Atropisomeric compounds have been discovered in pharmaceuticals and materials science, and their enantioselective syntheses have gained tremendous attention. Among strategies for catalytic atroposelective synthesis, desymmetrization provides robust and straightforward approaches to axially chiral biaryls. Due to the relative ease of substrate design compared to other atroposelective strategies, desymmetrization has emerged as a pivotal stage for converting fascinating chemistry into its atroposelective counterpart, despite challenges such as the formation of achiral products by subsequent catalytic reactions and the long distance between the reaction site and the stereogenic axis. This review offers a comprehensive overview of recent advancements in atroposelective desymmetrization using chiral organo‐ and metal catalysts, addressing challenges and solutions, and aims to provide insights into future developments in this field. [ABSTRACT FROM AUTHOR]

Sulfonium, selenonium, telluronium triflates, as well as chloronium, bromonium, and iodonium triflates have been examined in the model Schiff condensation as chalcogen‐ and halogen bond donating organocatalysts, respectively. The kinetic data indicated that the catalytic effect of the telluronium salt is provided via the decrease of enthalpy of activation of the reaction, whereas the catalytic effect of the iodonium salt – unexpectedly – is caused by the decrease of the value of the entropy of activation. In addition, it was experimentally shown that the catalytic activity of sulfonium and selenonium salts is significantly lower than that of chloronium and bromonium salts, but the latter pair of species is significantly less stable under the reaction conditions than the former pair. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles (MNPs) based on magnetite (Fe3O4) are attractive catalyst supports due to their high surface area, easy preparation, and facile separation, but they lack stability in acidic reaction media. The search for MNPs stable in oxidative acidic reaction media is a necessity if one wants to combine the advantages of MNPs as catalyst supports with those of iodine(III) reagents being environmentally benign oxidizers. In this work, immobilized iodophenyl organocatalysts on magnetite support (IMNPs) were obtained by crossed-linking polymerization of 4-iodostyrene with 1,4-divinylbenzene in the presence of MNPs. The obtained IMNPs were characterized by TGA, IR, SEM, STEM, and HAADF to gain information on catalyst morphology, average particle size (80–100 nm), and their core–shell structure. IMNP-catalysts tested in (i) the α-tosyloxylation of propiophenone 1 with meta-chloroperbenzoic acid (m-CPBA) and (ii) in the oxidation of 9,10-dimethoxyanthracene 3 with Oxone® as the side-oxidant showed a similar performance as reactions using stoichiometric amounts of iodophenyl. The developed IMNPs withstand strong acidic conditions and serve as reusable organocatalysts. They are recyclable up to four times for repeated organocatalytic oxidations with rates of recovery of 80–92%. This is the first example of a—(4-iodophenyl)polystyrene shell—magnetite core-structured organocatalyst withstanding strong acidic reaction conditions. [ABSTRACT FROM AUTHOR]

Fluorine's high electronegativity, lipophilicity, and metabolic stability make it a valuable element for drug design and development. Consequently, significant synthetic efforts have focused on introducing fluorine and fluorinated motifs into organic molecules, with the synthesis of trifluoromethyl ketones (TFMKs) recently attracting considerable attention. Building on our ongoing research on radical organofluorine chemistry, we present herein the divergent synthesis of trifluoromethyl ketones directly from olefins using readily available chloro‐ and bromotrifluoroacetone as synthetic precursors of the trifluoroacetonyl radical under photoredox catalysis. Mechanistic studies revealed that the divergence is attained through radical polar crossover (RPC) and hydrogen atom transfer (HAT) mechanisms. [ABSTRACT FROM AUTHOR]

Tertiary phosphines have been recognized as powerful organocatalysts for the Michael reaction, which is one of the most important atom-economical methods for carbon-carbon and carbon-heteroatom bond construction. In the presence of tertiary phosphines, a vast array of Michael acceptors and Michael donors can be coupled with each other under neutral and metal-free conditions to produce useful densely functionalized molecules. This review highlights the role of phosphine-catalyzed Michael reaction in cutting-edge areas, such as asymmetric synthesis, natural products synthesis, drug design, and polymer material science. As the central part of catalysis science, the kinetic and mechanistic issues are also discussed when possible. The review is organized by the type of the Michael acceptor and the Michael donor used in the reaction. [ABSTRACT FROM AUTHOR]

In the presence of catalytic amounts of a secondary amine (e. g. morpholine), skipped diynones undergo hydration/cyclization in aqueous acetonitrile to form γ‐pyrones in moderate to excellent yields (30–92 %). The first step of the process involves a trans‐stereoselective conjugate‐addition of morpholine to the ynone to form an intermediate E‐enaminone. Gradually this intermediate reacts with H2O yielding an acetylenic β‐diketone via nucleophilic vinylic substitution. Under the basic reaction conditions, acetylenic β‐diketones cyclize to γ‐pyrones. Primary amines fail to promote efficiently the process, as the initially formed Z‐configurated enaminones are reluctant to react smoothly under standard reaction conditions. [ABSTRACT FROM AUTHOR]

Anthraquinones have been used as the organophotoredox catalysts to catalyze metal‐free atom transfer radical polymerization (ATRP) under visible light irradiation. Polymers with different molecular weight and molecular weight distribution were obtained under different reaction conditions. The "living"/controlled nature of the polymerization was confirmed by the kinetic study, light on/off experiment and the block copolymer synthesis. The anthraquinones are found to catalyze ATRP via redox mechanism via sequential absorption of visible light. Evidence supported by control experiments showed that the excited anthraquinone radical anion or semiquinone anion generated by photo‐induced single electron reduction or subsequent protonation and further reduction were responsible for the initiation/activation of the polymerization. [ABSTRACT FROM AUTHOR]

The Michael addition reaction, a cornerstone of contemporary organic synthesis, has witnessed a resurgence of interest owing to its ability to forge intricate carbon‐carbon and carbon‐heteroatom bonds. In the past few years, heterocyclic compounds have been rigorously used as Michael donors, owing to their architectural diversity and distinct reactivity with or without the presence of base/transition metals/organocatalysts. This review encapsulates the latest breakthroughs in chemistry involving Michael addition reaction using heterocyclic compounds as Michael donors. It delivers a comprehensive update on developments in Michael addition reaction triggered by potent heterocycles since 2017, highlighting novel and innovative methodologies, with strategic insights. [ABSTRACT FROM AUTHOR]

Hydration reactions consist of the introduction of a molecule of water into a chemical compound and are particularly useful to transform alkynes into carbonyls, which are strategic intermediates in the synthesis of a plethora of compounds. Herein we demonstrate that L–cysteine can catalyse the hydration of activated alkynes in a very effective and fully regioselective manner to access important building blocks in synthetic chemistry such as β‐ketosulfones, amides and esters, in aqueous media. The mild reaction conditions facilitated the integration with enzyme catalysis to access chiral β‐hydroxy sulfones from the corresponding alkynes in a one‐pot cascade process in good yields and excellent enantiomeric ratios. These findings pave the way towards establishing a general method for metal‐free, cost‐effective, and more sustainable alkyne hydration processes. [ABSTRACT FROM AUTHOR]

N‐heterocyclic carbene catalysis has been developed as a versatile method for the enantioselective synthesis of complex organic molecules in organic chemistry. Merging of N‐heterocyclic carbene catalysis with transition metal catalysis holds the potential to achieve unprecedented transformations with broad substrate scope and excellent stereoselectivity, which are unfeasible with individual catalyst. Thus, this dual catalysis has attracted increasing attention, and numerous elegant dual catalytic systems have been established. In this review, we summarize the recent achievements of dual NHC/transition metal catalysis, including the reaction design, mechanistic studies and practical applications. [ABSTRACT FROM AUTHOR]

This work introduces a robust acid‐base catalytic system based on the zirconium‐based metal‐organic framework (Zr‐MOF) MOF‐808, selected for its open structure, high stability, and low presence of structural defects compared to other Zr‐MOFs. Four bifunctional benzoate ligands bearing free carboxylic acid (‐COOH) and nitrogen‐containing groups were introduced into the MOF‐808 using solvent‐assisted ligand exchange methods. Unlike other materials, the acid and base sites in the bifunctional MOF‐808 materials are situated in the same capping ligand, leading to a bifunctional behavior between the two neighboring sites. The system was tested for Knoevenagel condensation and deacetylation‐Knoevenagel tandem reactions, demonstrating high catalytic activity and excellent yields. Additionally, computational modeling provided insights into the catalytic mechanism and the role of the acid‐base sites. The study provides a better understanding of the unique behavior of the bifunctional MOF‐808 catalyst and offers prospects for designing new and efficient catalytic systems for organocatalysis. [ABSTRACT FROM AUTHOR]

Catalyst‐controlled diversity‐oriented synthesis (CatDOS) is an important research area for expanding molecular complexities and achieving high atomic economics. Many regiodivergent syntheses have been achieved through metal catalysis, covalent organocatalysis, and non‐covalent organocatalysis by controlling the molecular recognition function of the catalysts. However, the development of regiodivergent CatDOS through Brønsted base organocatalysis was relatively less developed than others so far. Numerous studies about Brønsted base organocatalysis have demonstrated the powerful molecular recognition abilities of their cationic conjugate acids mainly in controlling the stereoselectivity instead of the regioselectivity. This concept review aims to conceptualize a new perspective to consider the potential role of the cationic conjugate acid of Brønsted bases for regiodivergent CatDOS. Recent representative examples are selected to demonstrate the potential of cationic conjugate acids in site‐selectivity control in single bond and multiple bonds formation reactions. The summarized results show that even the conjugate acid of common tertiary amines, protic ammonium ions, could affect the regioselectivity in the early‐ or late‐stage step during multiple bonds formation after initial deprotonation. The results also suggested that the properties and ion‐pairing interactions of conjugate acid could be more important than the basicity of the base in controlling regioselectivity. Perspectives and hypotheses for explaining the mechanism of regioselectivity are also included in this review. [ABSTRACT FROM AUTHOR]

The organocatalytic conjugate addition of aldehydes to β‐nitroacrylates provides direct access to β‐ester‐γ‐nitroaldehydes and, thereby, common structural motifs of many bioactive compounds. However, the deactivation of amine‐based catalysts by alkylation with the highly electrophilic nitroacrylates hampers this reaction. Here, we show that the peptide H‐Mep‐dPro‐dGlu‐NH2, which is reluctant to undergo alkylation, catalyzes this reaction at low catalyst loading (0.5–1 mol %) within short reaction times (15–60 min) to yield a broad range of β‐ester‐γ‐nitroaldehydes with high stereoselectivity. Kinetic studies revealed that increased steric bulk on the β‐nitroacrylate enhances the reaction rate by hindering catalyst alkylation. [ABSTRACT FROM AUTHOR]

α-Cyanophosphonates, which are useful reagents for the Horner–Wittig reaction, were synthesized under solvent-free conditions by using a choline chloride–zinc chloride deep-eutectic solvent (DES) as a catalyst. This is only the second report on the synthesis of these compounds. In the previous report, diethyl trimethylsilyl phosphite was used as a reagent and TiCl4 as a catalyst, whereas in this study, both the reagent (triphenylphosphine) and the catalyst (choline chloride–zinc chloride DES) are cheaper, more readily available, and less harmful than those used in the previous work. Moreover, the process involves an interesting cascade reaction between a β-nitrostyrene and two equivalents of triphenyl phosphite, leading to the desired product by a new synthetic route. The products can be used in the pharmaceutical and agricultural industries, in addition to their synthetic applications in the preparation of α,β-unsaturated nitriles. The reactions were completed on using 20 mol% of DES at 80 °C in six hours. Ten different β-nitrostyrenes were synthesized in yields of 55–87% after purification. β-Nitrostyrenes containing electron-donating groups showed higher yields. The reaction failed when aliphatic or heteroaromatic nitroalkenes or β-nitrostyrenes with electron-withdrawing substituents were employed. Finally, three plausible mechanistic routes are proposed for the reaction, starting with the nucleophilic addition of triphenyl phosphite to the carbon, nitrogen, or oxygen atom in the α-position. [ABSTRACT FROM AUTHOR]

A truly organocatalytic approach to the Darzens reaction affording α,β-epoxy carbonyl compounds in good yields was developed taking advantage of the high basic strength and low nucleophilicity of cyclopropenimine superbases. The catalytic active free base can easily be generated in situ from its hydrochloride salt and maintained in the active deprotonated form by performing the reactions in a heterogeneous reaction system in the presence of excess potassium carbonate as a sacrificial base. [ABSTRACT FROM AUTHOR]

The increasing demand for deuterium‐labeled amino acids and derivatives has heightened interest in direct hydrogen/deuterium exchange reactions of free amino acids. Existing methods, including biocatalysis and metal catalysis, typically require expensive deuterium sources or excessive use of deuterium reagents and often struggle with site selectivity. In contrast, this binary catalysis system, employing benzaldehyde and Cs2CO3 in the presence of inexpensive D2O with minimal stoichiometric quantities, facilitates efficient hydrogen/deuterium exchange at the α‐position of amino acids without the need for protecting groups in the polar aprotic solvent DMSO. The process is highly compatible with most natural and non‐natural α‐amino acids and derivatives, even those with potentially reactive functionalities. This advancement not only addresses the cost and efficiency concerns of existing methods but also significantly broadens the applicability and precision of deuterium labeling in biochemical research. [ABSTRACT FROM AUTHOR]

In this study, we explored a method to distinguish between both enolizable regions of unsymmetrical 2,3‐diketones in organocatalytic domino reactions involving nitroalkenes. The selective formation of an enamine from only one side of the molecule was made possible by the use of optically pure 2‐(trifluoromethyl)pyrrolidine. This catalyst, remarkably enhancing the reaction, owes its efficacy to a unique interplay between basicity and nucleophilicity. These features caused the enolization of the substrate at the second possible site to be omitted. The approach resulted in excellent regio‐ diastereo‐ and enantioselectivity (91–99 % ee) across various nitroalkenes, leading to the synthesis of novel cyclopentanone derivatives with three contiguous stereogenic center. [ABSTRACT FROM AUTHOR]

The catalytic decarboxylation of malonic acid half oxy‐ and thioesters, β‐ketocarboxylic acids, and their related compounds is a straightforward, powerful, and atom‐economical strategy for the in‐situ formation of enolates, which are important and well‐studied synthons for various functional materials and natural products. This strategy, inspired by the biosynthesis of polyketides and fatty acids, is an attractive method for synthesizing enols from carboxyl compounds with less reactive α‐hydrogen atoms under mild conditions. In addition, these reactions are environmentally friendly and are of great interest to chemists because the use of a stoichiometric amount of base can be avoided, and the only byproduct is CO2. Thus far, remarkable progress has been made, especially in the field of organocatalytic enantioselective decarboxylation reactions, allowing for the stereocontrolled formation of new C−H, C−C, C−heteroatom, and C−X bonds. This review provides a comprehensive overview of organocatalytic enantioselective decarboxylation reactions and highlights the significant progress made since 2020. In particular, it focuses on chiral catalyst systems and transition states as key parameters for decarboxylation reactions. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: An efficient and highly stereoselective synthetic method to access polycyclic chromanes has been achieved through organocatalyzed one‐pot step‐wise reactions involving 2‐hydroxycinnamaldehydes, 2‐aminochalcones, and malononitrile as substrates. The reactions underwent a quintuple process by aza‐Michael/Michael/Knoevenagel/oxa‐Michael/aldol‐type reaction in sequence to give products bearing 3 new generated rings and 5 chiral centers in moderate to quantitative yields with excellent stereoselectivities. A novel retro‐reaction mechanism was discovered in the synthetic transformations of products. [ABSTRACT FROM AUTHOR]

The catalytic application of chiral phosphoric acids (CPAs) from 2004 to date represents a true milestone for asymmetric organocatalysis. However, not only the free acids can be conveniently employed in numerous different asymmetric synthetic methodologies, thus being strictly compliant to the concept of "organocatalysis", but also their metal salts. This review focuses on asymmetric reactions in which the catalyst is a chiral alkali or alkaline‐earth metal phosphate. [ABSTRACT FROM AUTHOR]

Controlled radical copolymerizations present attractive avenues to obtain polymers with complicated compositions and sequences. In this work, we report the development of a visible‐light‐driven organocatalyzed controlled copolymerization of fluoroalkenes and acyclic N‐vinylamides for the first time. The approach enables the on‐demand synthesis of a broad scope of amide‐functionalized main‐chain fluoropolymers via novel fluorinated thiocarbamates, facilitating regulations over chemical compositions and alternating fractions by rationally selecting comonomer pairs and ratios. This method allows temporally controlled chain‐growth by external light, and maintains high chain‐end fidelity that promotes facile preparation of block sequences. Notably, the obtained F/N hybrid polymers, upon hydrolysis, afford free amino‐substituted fluoropolymers versatile for post modifications toward various functionalities (e.g. amide, sulfonamide, carbamide, thiocarbamide). We further demonstrate the in situ formation of polymer networks with desirable properties as protective layers on lithium metal anodes, presenting a promising avenue for advancing lithium metal batteries. [ABSTRACT FROM AUTHOR]

Silicon-stereogenic chiral organosilanes have found increasing applications in synthetic chemistry, medicinal chemistry, and materials science. In this context, various asymmetric catalytic methods have been established for the diverse synthesis of silicon-stereogenic silanes. In particular, asymmetric organocatalysis is emerging as an important and complementary synthetic tool for the enantioselective construction of silicon-stereocenters, along with the rapid development of chiral-metal catalyzed protocols. Its advent provides a powerful platform to achieve functionalized silicon-stereogenic organosilanes with structural diversity, and should lead to great development in chiral organosilicon chemistry. In this Tutorial Review, we highlight these latest achievements from two aspects: desymmetrizations of prochiral tetraorganosilanes and dynamic kinetic asymmetric transformations of racemic organosilanes by employing five organocatalytic activation modes. The advantages, limitations and synthetic value of each protocol, as well as the synthetic opportunities still open for further exploration, are also discussed. [ABSTRACT FROM AUTHOR]

The synthesis of bis-lactone and butenolide derivatives was described using alkylidene Meldrum's acid as nucleophiles. The process operates in a triple cascade through an auto tandem catalysis promoted by DBU. [ABSTRACT FROM AUTHOR]

PIII/PV redox cycling has recently emerged as a valuable strategy to minimized the chemical waste generated by phosphine‐mediated reaction, as well as enabling asymmetric transformation. In this article, we detail our contribution to this field by designing a series of diversely functionalized, electron‐rich bridgehead phosphine oxides with structural features that make them well‐suited as PIII/PV redox organocatalysts. Their catalytic performance has been assessed in various model reactions, including Wittig or Staudinger reactions, along with the reduction of activated alkenes and allenes. For each of these scenarios, we performed a comparative analysis with existing catalysts in order to demonstrate the applicability and limitation of methanophosphocines. [ABSTRACT FROM AUTHOR]

2,2,6,6′‐Tetramethylpiperidine‐N‐oxyl (TEMPO) is a highly efficient oxidation catalyst, valued for its environmentally benign nature, particularly in comparison to transition‐metal catalysts. Despite their merits, TEMPO‐based catalysts are not notably cost‐effective. Immobilization of TEMPO onto supports offers a promising strategy to overcome this limitation. In this work, we present the synthesis and application of immobilized TEMPO catalysts 2–5, prepared via a straightforward condensation reaction, for the aerobic oxidation of alcohols. These catalysts demonstrate remarkable activity for alcohol oxidations under continuous‐flow conditions, employing nitric acid as the co‐catalyst. Notably, catalyst 2 immobilized by COOH silica gel exhibits outstanding performance for the oxidation of benzyl alcohol by oxygen gas, achieving a turnover frequency (TOF) of 15 h−1 and a turnover number (TON) exceeding 300. Catalyst 2 further demonstrates broad substrate scope, effectively oxidizing primary, secondary, and benzylic alcohols. Post‐reaction analysis of spent catalyst 2 reveals that deactivation primarily stems from nitrosation of the N−O bond. Interestingly, the amide moiety remains intact despite the harsh acidic reaction conditions. [ABSTRACT FROM AUTHOR]

A highly efficient catalytic nucleophilic addition of 3‐substituted oxindoles to 3‐diazo oxindoles has been achieved. This method relies on an organic base catalysis system, which can simultaneously activate 3‐substituted oxindoles as a nucleophile and the diazo compounds as a strong N‐terminal electrophile. Importantly, this approach could yield a broad array of functionalized isatin‐hydrazones featuring an adjacent tetrasubstituted carbon centre of the N(sp3) atom. [ABSTRACT FROM AUTHOR]

[Display omitted] Asymmetric cycloaddition/intramolecular rearrangement domino reaction of 2-(2-hydroxybenzylideneamino)- malonates with 4-arylidene-2-phenyloxazol-5(4 H)-ones can be efficiently carried out in sub- or supercritical carbon dioxide to afford (3 R ,3a S ,9b R)-3-aryl-3a-benzamido-4-oxo-1,3a,4,9b-tetrahydrochromeno[4,3- b ]pyrrole-2,2(3 H)- dicarboxylates in high yields with up to 99% ee. Excellent stereoinduction is provided in this process by the use of bifunctional hybrid organocatalyst consisting of squaramide (thiourea) and chiral tertiary amine units. [ABSTRACT FROM AUTHOR]

Novel chiral tetraaza‐bridged calix[4]arene[2]triazine‐based organocatalysts were synthesized and used for catalytic asymmetric Michael reaction of acetylacetone to various aromatic nitrostyrenes. Chiral subunits (R)‐ and (S)‐1,2,3,4‐tetrahydro‐1‐naphthylamine were attached to the tetraaza‐bridged calix[4]arene[2]triazine platform in both enantiomeric forms. The R configuration of the major enantiomer of the Michael product was obtained when 3a was used as catalyst, and the S configuration was obtained when 3b was used as catalyst. This indicated that the configuration of the Michael product was controlled by the chiral calixarene moiety. The Michael adducts were obtained in excellent yields (91%) and enantioselectivities (98%). [ABSTRACT FROM AUTHOR]

A new eco-friendly method for the synthesis of mono- and multifunctional organosulfur compounds, based on the process between ynals and thiols, catalyzed by bulky N-heterocyclic carbene (NHC), was designed and optimized. The proposed organocatalytic approach allows the straightforward formation of a broad range of thioesters and sulfenyl-substituted aldehydes in yields above 86%, in mild and metal-free conditions. In this study, thirty-six sulfur-based derivatives were obtained and characterized by spectroscopic methods. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Dibenzo[b,f][1,5]diazocines are a class of eight‐membered heterocycles, which exhibit unique rigid saddle‐shaped structure and possess inherent chirality. In this study, we report a convenient and straightforward method for the catalytic enantioselective synthesis of these unique chiral molecules through chiral phosphoric acid‐catalyzed dimerization of 2‐acylbenzoisocyanates. Notably, the addition of corresponding 2‐acylaniline as the co‐catalyst significantly improved the efficiency of these reactions, and a simple phase separation operation resulted in products with excellent enantiopurity. Experimental studies were performed to elucidate the mechanism behind these reactions, leading to the proposal of a plausible reaction mechanism based on the study findings. [ABSTRACT FROM AUTHOR]