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Herein, we present an efficient and atom‐economic tandem hydroformylation organocatalyzed Friedel‐Crafts reaction sequence for the synthesis of diindolylmethanes. Classic syntheses have relied on (Lewis) acid activation of aldehydes, which are often not commercially available and rather sensitive in handling. In contrast, the combination of rhodium‐catalyzed hydroformylation and subsequent organocatalytic activation of the in‐situ formed aldehydes allows the use of readily available and stable alkenes with various functional groups while avoiding acidic conditions to expand the range of available diindolylmethanes. A broad scope of diindolylmethanes was prepared in yields up to 85 % demonstrates the utility of the presented method. [ABSTRACT FROM AUTHOR]

A light‐driven dual and ternary catalytic aza‐Wacker protocol for the construction of 3‐pyrrolines by partially disulfide‐assisted selenium‐π‐acid multicatalysis is reported. A structurally diverse array of sulfonamides possessing homopolar mono‐, di‐ and trisubstituted olefinic double bonds is selectively converted to the corresponding 3‐pyrrolines in up to 95 % isolated yield and with good functional group tolerance. Advanced electrochemical mechanistic investigations of the protocol suggest a dual role of the disulfide co‐catalyst. On the one hand, the disulfide serves as an electron hole shuttle between the excited photoredox catalyst and the selenium co‐catalyst. On the other hand, the sulfur species engages in the final, product releasing step of the catalytic cycle by accelerating the β‐elimination of the selenium moiety, which was found in many cases to lead to considerably improved product yields. [ABSTRACT FROM AUTHOR]

A three‐component multicomponent approach has been developed at room temperature for the synthesis of 4H‐pyrano[3,2‐c]quinoline‐3‐carbonitriles. The all synthesized products were afforded in short reaction time with excellent yield using BABCO catalyst. The process is proficient with good tolerance of functional groups and well‐explored substrate scope. [ABSTRACT FROM AUTHOR]

Herein, we demonstrated a visible light mediated tandem oxidation–organo catalyzed C−S bond functionalization protocol for the cleavage of aromatic C−S bond. The investigation encompassed the functionalization of C−S bonds within sulfones, sulfoxides, and aliphatic sulfide derivatives. However, the process of functionalizing the C−S bond in aromatic sulfides remains uncertain. The presented protocol demonstrates the C−S bond functionalization on benzo[b]benzo[4,5]thieno[2,3‐d]thiophene derivative and amines including primary and secondary amines as well. A radical mediated mechanism was proposed for the tandem oxidation–organocatalyzed C−S bond functionalization protocol. [ABSTRACT FROM AUTHOR]

α‐Haloenals, especially, α‐bromoenals considered as one of the important building blocks in organic synthesis. They can participate in various (3+2)‐, (3+3)‐, (3+4)‐, and (2+4)‐annulation reactions with other organic molecules in the presence of an NHC catalyst to produce enantioenriched carbo‐, and heterocyclic compounds. Herein, we have described NHC‐catalyzed enantioselective transformations of α‐bromoenals in the synthesis of various heterocycles, and carbocycles, as well as acyclic organic compounds. [ABSTRACT FROM AUTHOR]

The direct utilization of H2S in polymerization is rarely reported. Here step polymerization of H2S and diacrylates using commercially available organic bases as the catalysts is reported. Poly(thioether‐ester)s are successfully synthesized in an atom‐economical way, as confirmed by 1H NMR spectra, and the molecular weights of these poly(thioether‐ester)s can be up to 64.7 kDa as determined by the gel permeation chromatography, which also shows the polymerization of H2S with diacrylates is stepwise manner. The calculation results show that H2S is first deprotonated by organic base, and the generated HS‐ attacks the double bond of diacrylates through anionic Michael addition, to form the intermediate with double bond and ─SH ends or two ─SH ends (slight excess H2S used). The continuous self‐Michael addition of the polymer species with double bond and ─SH ends is the main manner for chain growth. The resultant polymers exhibit tensile strength and elongation at breaks of as high as 21.6 MPa and 1031%, respectively and can be chemically recycled. This work provides a facile and atom‐economical method to produce sulfur‐containing polymers by directly using commercially available H2S. [ABSTRACT FROM AUTHOR]

Acyl fluorides, carbamoyl fluorides and fluoroformates have been employed as efficient reagents in a number of organic syntheses. Their application in catalytic transformations, however, began to be explored in the early 2000s. Recently, these reagents have increasingly gained attention owing to their unique reactivity in diverse catalytic systems. This review aims to overview the advancements in the development of catalytic processes, including transition‐metal catalysis, organocatalysis, and cooperative NHC/photoredox catalysis, where these organofluorine compounds are employed as acyl, carbamoyl, and ester group donors. [ABSTRACT FROM AUTHOR]

Chalcogen bond catalysis, particularly cationic hypervalent chalcogen bond catalysis, is considered to be an effective strategy for organocatalysis. In this work, the cationic hypervalent chalcogen bond catalysis for the Povarov reaction between N‐benzylideneaniline and ethyl vinyl ether was investigated by density functional theory (DFT). The catalytic reaction involves the cycloaddition process and the proton transfer process, and the rate‐determining step is the cycloaddition process. Cationic hypervalent tellurium derivatives bearing CF3 and F groups exhibit superior catalytic activity. For the rate‐determining step, the Gibbs free energy barrier decreases as the positive electrostatic potential of the chalcogen bond catalysts increases. More importantly, the Gibbs free energy barrier has a strong linear correlation with the electrostatic energy of the chalcogen bond in the catalyst‐substrate complex. Furthermore, the catalytic reactions include the endo pathway and exo pathway. The C−H⋅⋅⋅π interaction between the substituent of the ethyl vinyl ether and the aryl ring of the N‐benzylideneaniline contributes to the endo‐selectivity of the reaction. This research contributes to a deeper understanding of chalcogen bond catalysis, providing insights for designing chalcogen bond catalysts with high performance. [ABSTRACT FROM AUTHOR]

Exchanging oxygen in the functional group C=O (i. e. carbonyl) for the less electronegative Group 16 elements, sulfur or selenium, unexpectedly enhances the electronegativity of the C=X group in π‐conjugated molecules and reduces the molecular π HOMO–LUMO energy gap. Quantum‐chemical analyses revealed that the steric size of the chalcogen atom X is at the origin of this seemingly counterintuitive behavior. This tuning of the chemical properties of carbonyl compounds by varying the chalcogen atom size in the C=X bond can be applied in many fields of chemistry. This concept article delineates several useful applications in the fields of organocatalysis, supramolecular chemistry, and photo(electro)chemistry. [ABSTRACT FROM AUTHOR]

Enantioselective access to polycyclic tetrahydroxanthone compounds was achieved through an organocatalyzed cascade reaction of alkene‐substituted 1,3‐diketones and alkenyloxindoles, using quinine‐derived squaramide as an efficient catalyst. It afforded a variety of optically active spirooxindole‐based tetrahydroxanthones with 18–94% yields, >19:1 dr, and 86–99% ee. [ABSTRACT FROM AUTHOR]

The Friedel‐Crafts reaction stands as a powerful synthetic tool for C−H functionalization of aromatic feedstocks, which is conventionally realized through electrophilic alkylation and acylation. The burgeoning interests in axially chiral compounds across diverse fields have spurred extensive exploration of this classic transformation for catalytic atroposelective synthesis. Consequently, the past decade has witnessed the rapid expansion of various non‐canonical Friedel‐Crafts reactions, including electrophilic arylation, alkenylation, halogenation, sulfenylation, and amination of aryl C−H bonds, thereby delving into new chemical spaces. A range of catalytic atroposelective synthetic methods have been devised for these significant arene C−H functionalization. This review provides a comprehensive overview of the cutting‐edge catalytic synthesis of atropoisomers through non‐canonical Friedel‐Crafts reactions, categorized into three parts based on the type of bond formation on the aromatics: C(sp2)−C(sp3) bond formations, C(sp2)−C(sp2) bond formations and C(sp2)−heteroatom bond formations. The richness of electrophiles and the modulation of atroposelectivity by diverse chiral organocatalysts, particularly chiral Brønsted acids, are elucidated. We anticipate that the repertoire of asymmetric Friedel‐Crafts reaction will continue to flourish and to be demonstrated in not only scientific researches but also industrial organic synthesis. [ABSTRACT FROM AUTHOR]

A novel bifunctional isothiourea derived from a tetraarylphosphonium salt catalyzes the coupling reaction of monosubstituted epoxides with 1 atm of carbon dioxide to afford five‐membered cyclic carbonates in high yields. Thiourea and urea groups are also effective hydrogen bond donors for the carbon dioxide fixation. Comprehensive mechanistic studies on this catalysis using theoretical calculations disclosed key hydrogen bond interactions between catalysts and intermediates, which relied upon orientation of the binding modes. [ABSTRACT FROM AUTHOR]

The decarboxylative addition of substituted malonic acid half oxyesters (SMAHOs) to dialkyl azodicarboxylates is described. The reaction was promoted by 1,4‐diazabicyclo[2.2.2]octane (DABCO) as an organocatalyst in heated toluene. High yields of the coupling products were generally obtained, and the scope of the reaction proved rather important with the potential presence of functionalized side chains at the α‐position, affording an original access to α‐aminoester derivatives. [ABSTRACT FROM AUTHOR]

Synthesis of heterocyclic compounds is fundamental for all the research area in chemistry, from drug synthesis to material science. In this framework, catalysed synthetic methods are of great interest to effective reach such important building blocks. In this review, we will report on some selected examples from the last five years, of the major improvement in the field, focusing on the most important conventional catalytic systems, such as transition metals, organocatalysts, to more sustainable ones such as photocatalysts, iodine‐catalysed reaction, electrochemical reactions and green innovative methods. [ABSTRACT FROM AUTHOR]

In this study, we provide a theoretical explanation for the experimentally observed decrease in the organocatalytic activity of N-aryl imidazolylidenes methylated at the C4/5-H positions in the benzoin condensation of aromatic aldehydes. A comparative quantum chemical study of energy profiles for the NHC-mediated benzoin condensation of furfural has revealed a high energy barrier to the formation of the IPrMe-based furanic Breslow intermediate that can be attributed to the negative steric interactions between the imidazole backbone methyl groups and N-aryl substituents. [ABSTRACT FROM AUTHOR]

Non‐covalent interactions play an important role in all sub‐fields of chemistry, including catalysis, where interactions of different natures can work together to improve reactivitiy and selectivity. Several families of molecules that incorporate both hydrogen bond (HB) and halogen bonding (XB) donors have already been studied. However, there is a lack of data on how grafting HB donors to iodoazolium salts could impact their association and reactivity properties. Herein, we disclose the synthesis of a library of iodoazolium salts bearing varied HB donors, along with a study of their physico‐chemical properties using different techniques (X‐ray diffraction, 31P NMR, ITC) and their behavior in catalysis. Even though no clear‐cut evidence of cooperation between XB and HB could be obtained through physico‐chemical evaluations, a iodoazolium salt bearing a urea function displayed better conversion and product selectivity in a Ritter reaction than all other activators lacking one or the other function. [ABSTRACT FROM AUTHOR]

We report an approach to the diastereoselective synthesis of 1,2‐disubstituted heterocyclic aziridines. A Brønsted acid‐catalyzed conjugate addition of anilines to trisubstituted heterocyclic chloroalkenes provides an intermediate 1,2‐chloroamine. Diastereocontrol was found to vary significantly with solvent selection, with computational modelling confirming selective, spontaneous fragmentation in the presence of trace acids, proceeding through a pseudo‐cyclic, protonated intermediate and transition state. These chloroamines can then be converted to the aziridine by treatment with LiHMDS with high stereochemical fidelity. This solvent‐induced stereochemical enrichment thereby enables an efficient route to rare cis‐aziridines with high dr. The scope, limitations, and mechanistic origins of selectivity are also presented. [ABSTRACT FROM AUTHOR]

Despite the significant role of pyruvic acid in biotransformations, the utilization of pyruvates in the field of catalytic asymmetric synthesis has been unexpectedly limited. This statement also applies to enamine catalysis, in which pyruvates seem to be challenging substrates. Recently, the first illustration of the asymmetric addition of pyruvic acid to β‐nitrostyrenes, catalyzed by a NahE enzyme using the enamine mechanism, has appeared in the literature. Now, we demonstrate pyrrolidine‐based catalyst can mimick enamine mechanism used by this enzyme to activate pyruvates in the asymmetric addition to structurally diverse nitroalkenes to produce highly enantioenriched Michael adducts without the limitations in substrate structures associated with biocatalysts. In addition to confirming that optically pure pyrrolidines can serve as ultimately small organic catalysts in pyruvate activation, we present an exceedingly simple and versatile method for the synthesis of optically pure γ‐nitro acids, which are precursors for well‐known active pharmaceutical ingredients namely GABA derivatives [ABSTRACT FROM AUTHOR]

Gold complexes, because of their unique carbophilic nature, have evolved as efficient catalysts for catalyzing various functionalization reactions of C–C multiple bonds. However, the realization of enantioselective transformations via gold catalysis remains challenging due to the geometrical constraints and coordination behaviors of gold complexes. In this context, merged gold/organocatalysis has emerged as one of the intriguing strategies to achieve enantioselective transformations which could not be possible by using a single catalytic system. Historically, in 2009, this field started with the merging of gold with axially chiral Brønsted acids and chiral amines to achieve enantioselective transformations. Since then, based on the unique reactivity profiles offered by each catalyst, several reports utilizing gold in conjunction with various chiral organocatalysts such as amines, Brønsted acids, N-heterocyclic carbenes, hydrogen-bonding and phosphine catalysts have been documented in the literature. This article demonstrates an up-to-date development in this field, especially focusing on the mechanistic interplay of gold catalysts with chiral organocatalysts. [ABSTRACT FROM AUTHOR]

Process oil, one of the primary chemicals used in the compounding of tire tread, is an important ingredient because it makes up the largest portion of the tire tread and can be modified to change the tire's characteristics. We designed a new process oil by controlling the number of functional groups in the oil molecules, resulting in the incorporation of multiple coordination sites followed by the enhanced dispersion of silica filler particles which are commonly used in tire tread. Through the introduction of a new recyclable organocatalyst, specifically 4-(N,N-dimethylamino)pyridine benzyl bromide salt (DMAP-BB), we have developed a selective ring opening system that can be used to synthesize various types of acidesterified soybean oils (ASOs) (99% conversion and up to 93% selectivity), which have multiple ester groups with diverse molecular structures. Furthermore, excellent efficiency of DMAP-BB was observed under the optimized conditions with an average 96% recovery of the catalyst in five cycles without loss of conversion or selectivity. Finally, these newly developed bio-based processing oils are revealed to be highly efficient in the manufacturing process of a styrene-butadiene rubber (SBR) composite, i.e., tire tread. A silica-filled SBR composite prepared with a mixture that included palmitic acid-esterified soybean oil with 99% selectivity (PASO99) exhibited a remarkable Payne effect in an un-vulcanized batch, suggesting excellent dispersibility of the silica filler during compounding. This can be observed through the change in the storage modulus (G'), which decreased from 1315 kPa for SBR/ESO to 1008 kPa for SBR/PASO99 (23% improvement). We also found that excellent viscoelastic and mechanical properties could be achieved in the vulcanized batch of SBR/PASO99, which includes outstanding rolling resistance (tan d at 60 °C = 0.158 for SBR/ESO to tan d at 60 °C = 0.116 for SBR/PASO99, 27% improvement) and abrasion resistance (DIN abrasion loss = 180 mm3 for SBR/ESO to DIN abrasion loss = 140 mm3 for SBR/PASO99, 22% improvement). We believe that the implementation of these novel fully bio-based process oils can offer significant opportunities for reducing the environmental footprint of rubber goods and promoting the development of sustainable, high-performance tire. [ABSTRACT FROM AUTHOR]

Polycyclic compounds bearing a complex heterocyclic core such as an aromatic heterocycle "fused" with one or more functionalized rings, are widespread leading molecules in the domain of synthetic organic chemistry and pharmaceuticals. Although many synthetic methodologies have been devised to access achiral, fused heteroaromatic scaffolds, or related chiral variants adorned with out‐of‐cycle stereogenic elements, equally efficient strategies to afford chiral heterocycles featuring in‐cycle stereocenters, exist to a lesser extent and presently represent a growing field of investigation. The mild, organocatalytic generation of elusive ortho‐quinodimethane intermediates (oQDMs), derived from suitable heteroaromatic carbonyl‐ or carbonyl‐like pronucleophiles has recently proved successful in the synthesis of such peculiar chiral architectures via stereoselective [4+2] cycloadditions. This review provides an overview of the most important advances attained in this field over the last decade. [ABSTRACT FROM AUTHOR]

The epoxidation of alkenes has altered and reshaped the way scientists think in modern organic synthesis. Herein, a novel, sustainable and eco‐friendly protocol for the epoxidation of alkenes is reported, utilizing hydrogen peroxide as the green oxidant and, for the first time, hydroxamic acid derivatives as the organocatalyst. The presented methodology is very effective, leading to good to high yields for the oxidation of a variety of olefins, while various functional groups are well tolerated. Mechanistic studies utilizing direct infusion high resolution mass spectrometry (DI‐HRMS) provide strong evidence for the mechanism of the organocatalytic oxidation. [ABSTRACT FROM AUTHOR]

A three-component organocatalytic reaction of 1,3-dipolar cycloaddition between the in situ generated azomethine ylides and 3-substituted 1,2-diphenylcyclopropenes is described. The azomethine ylides have been generated via condensation of aromatic compounds (such as isatins and acenaphthenequinone) with benzylamines. The reaction has afforded derivatives of 3-azabicyclo[3.1.0]hexane, spiro-fused with the fragments of 2-oxindole and acenaphthylene-1(2H)-one. The cycloadducts have been obtained with yield up to 91%, mainly as individual diastereomers. The influence of bifunctional squaramide-based organocatalysts on the course of these three-component reactions has been investigated. Antiproliferative activity of selected synthesized compounds with respect to the human erythromyelosis (K562) and melanoma (Sk-mel-2) cell lines has been assessed in vitro by means of MTS analysis. [ABSTRACT FROM AUTHOR]

Four bifunctional, noncovalent amine-squaramide organocatalysts were prepared from camphor in five steps. The stereochemistry of the prepared catalysts was thoroughly analyzed using various spectroscopic techniques. Their organocatalytic activity was investigated in the Michael addition of acetylacetone to trans-β-nitrostyrene. The addition product was formed in complete conversion and with an enantioselectivity of up to 77% ee. In the reactions catalyzed by the 2-exo-3-endo catalysts, the major (S)-enantiomer was formed, whereas in the presence of 2-endo-3-endo catalysts, the (R)-enantiomer was formed as the major product. [ABSTRACT FROM AUTHOR]

In this communication, a straighforward asymmetric synthesis of spiro‐indoline‐pyrazolone compounds is described. This methodology consists in a formal [4+1] cycloaddition reaction of 4‐bromopyrazolones and aza‐ortho‐quinone methides generated in situ catalyzed by a bisquinine‐derived squaramide in CHCl3 under basic conditions. A variety of chiral spirocyclic compounds bearing a pyrazolone and an indoline moieties were obtained in moderate to good yields (up to 68 %) and moderate to excellent enantioselectivities (up to 93 % ee). [ABSTRACT FROM AUTHOR]

Near‐UV‐light‐induced oxidative conversion of cyclic and linear alcohols into corresponding carbonyl compounds was achieved in the supercritical CO2 medium under the action of molecular oxygen in the presence of 2‐fluoroanthraquinone (1 mol %), a simple and available metal‐free photocatalyst. A thorough examination of the impact of various process parameters on the reaction outcome allowed to identify a narrow density area at ~0.3 g/cm3 in the vicinity of the medium critical point and optimal reaction conditions (~45 °C, ~8.4 MPa) where up to 99 % conversions and 65–93 % yields of the oxidation products could be attained. Furthermore, it has been shown that compressed atmospheric air, a far cheaper and safer oxidizer than pure oxygen, can be applied to the reaction. Based on the experimental data, a plausible mechanism of the photocatalytic process has been proposed comprising photocatalyst excitation with near‐UV light followed by the hydrogen atom transfer (HAT) as the key stages. [ABSTRACT FROM AUTHOR]

Aliphatic polyester is an important polyester material with good biocompatibility and degradability, which can be synthesized through ring-opening alternating copolymerization (ROAC) of epoxides and anhydrides. Herein, density functional theory (DFT) is used to explore the mechanism of ROAC of epoxides (propylene oxide (PO), styrene oxide (SO), epichlorohydrin (ECH), and cyclohexane oxide (CHO)) and phthalic anhydride (PA) catalyzed by bis(triphenylphosphine) ammonium chloride (PPNCl) and ureas. It was found that the ring-opening polymerization (ROP) of epoxides is the rate-controlling step, and the benzyl alcohol (BnOH) as the initiator has little effect on the polymerization activity, which was consistent with previous experimental results. Calculated comparisons of the ROAC activity of CHO/PA catalyzed by four different ureas indicate that as the Lewis acidity of the urea increased, the energy barriers of the copolymerization increased and the activity decreased. The main reason was that the strong hydrogen-bonding interactions stabilized the key intermediate of the rate-controlling step and inhibited subsequent monomer insertion. Based on this, a series of new ureas with higher catalytic activity were designed by introducing electron-donating substituents. In SO polymerization, increasing the Lewis acidity of urea can improve the SO regioselectivity. In addition, the monomer ECH with CH2Cl shows higher activity of ROAC than PO and SO, which could be ascribed to the fact that the strong electron-withdrawing Cl atom stabilizes the transition state in the rate-controlling step and reduces the reaction energy barrier. [ABSTRACT FROM AUTHOR]

In the past few decades, N-heterocyclic carbenes (NHCs) have opened the new field of organocatalysis in synthetic organic chemistry. This review highlights the dramatic progress in the field of NHC-catalyzed C–O bond formation based on the activation of aldehyde C(sp2)–H bonds. The oxidative and redox transformations for the synthesis of various molecules with structural diversity and complexity are summarized. Furthermore, new methods and strategies for NHC catalysis are emerging continuously; thus, cooperative catalysis with Brønsted acid, hydrogen-bonding catalyst, transition-metal catalyst, and photocatalyst are also described. [ABSTRACT FROM AUTHOR]

Catalysis field wherein a tiny organic molecule like l-proline is an efficient and selectively catalyzed organic reaction. Catalyst-supported organic synthesis is confirmed to be involved in the fast synthesis of novel compounds with selectivity and enhanced biological activities. l-proline catalyzed reactions are valuable tools for the making of different heterocycles, acyclic, and carbocyclic scaffolds that signify the main framework of most of the bio-active compounds. A few decades ago, novel tools for the manufacturing of bio-active molecules had a huge impact on organic chemistry. Subsequently, the synthesis of biologically important heterocycles through a synthetically proficient and environmentally benign route is the important purpose of modern synthetic chemistry. In this review, we discuss only l-proline catalyzed organic reactions (including condensation, addition, asymmetric, multi-components, and other modular reactions) for the sustainable synthesis of biologically promising heterocycles in a single trencher that may provide as a piece of reliable literature for further research in this field.

A lipophilic tricationic cobalt tris(chelate) complex of 2-guanidinobenzimidazole (GBI), [Co(GBI)3]3+ 3BArf– (23+ 3BArf–; BArf = B(3,5-C6H3(CF3)2)4), is prepared from the corresponding hydrophilic trichloride salt and Na+ BArf– or Ag+ BArf– under aqueous/organic biphasic conditions. This racemic chiral complex, which is obtained as a mer isomer and a tetradecahydrate as assayed by NMR and TGA, is an excellent catalyst for additions of dimethyl malonate and indole to trans-ß-nitrostyrenes (10 mol%), and cycloadditions of CO2 to epoxides (1 mol%; solvent-free). Average yields (84 %, 91 %, 81 %) and rates are slightly greater than those obtained with a monocationic ruthenium GBI complex [(η5-C5H5)Ru(CO)(GBI)]+ BArf– prepared earlier. Attempted crystallization of 23+ 3Cl– gives a tetramethanol solvate of a salt derived from loss of two molecules of HCl. This can be represented as [Co(GBI)(GBI–H)2]+ Cl−, and bond lengths and hydrogen bonding motifs are carefully analyzed, especially in the context of dominant chelate resonance forms.

Cyclopropenone has emerged as a highly versatile precursor in organic synthesis due to its diverse reactivity. The cyclopropenone derivatives could undergo various transformations such as cycloaddition reactions, ring-opening reactions, and isomerization reactions in the presence of different chemical reagents. Over the years, significant progress has been made in the manipulation of cyclopropenones for the construction of various carbocycles, heterocycles, and other useful organic compounds. Despite several reviews that have concerned the chemistry and reactions of cyclopropenones, the utility of such motifs in the construction of carbocycles and heterocycles has rarely been reported. Herein, we report recent advancements in the cycloaddition reactions of cyclopropenones as versatile synthetic precursors towards the synthesis of compounds with synthetic and biological significance.

Abstract Axially chiral thioethers and sulfoxides emerge as two pivotal classes of ligands and organocatalysts, which have remarkable features in the stereoinduction of various asymmetric transformations. However, the lack of easy methods to access such molecules with diverse structures has hampered their broader utilization. Herein, an oxidative kinetic resolution for sulfides using a chiral bifunctional squaramide as the catalyst with cumene hydroperoxide as the terminal oxidant is established. This asymmetric approach provides a variety of axially chiral thioethers as well as sulfoxides bearing both axial and central chirality, with excellent diastereo‐ and enantioselectivities. This catalytic system also successfully extends to the kinetic resolution of benzothiophene‐based sulfides. Preliminary mechanism investigation indicates that the multiple hydrogen bonding interactions between the bifunctional squaramide catalyst and substrates play a crucial role in determining the enantioselectivity and reactivity.

Abstract The efficient synthesis of chiral 2,2‐disubstituted indolin‐3‐ones is of great importance due to its significant synthetic and biological applications. However, catalytic enantioselective methods for de novo synthesis of such heterocycles remain scarce. Herein, a novel cyclizative rearrangement of readily available anilines and vicinal diketones for the one‐step construction of enantioenriched 2,2‐disubstituted indolin‐3‐ones is presented. The reaction proceeds through a self‐sorted [3+2] heteroannulation/regioselective dehydration/1,2‐ester shift process. Only chiral phosphoric acid is employed to promote the entire sequence and simplify the manipulation of this protocol. Various common aniline derivatives are successfully applied to asymmetric synthesis as 1,3‐binuclephiles for the first time. Remarkably, the observed stereoselectivity is proposed to originate from an amine‐directed regio‐ and enantioselective ortho‐Csp2‐H addition of the anilines to the ketones. A range of synthetic transformations of the resulting products are demonstrated as well.

We report herein a rare example of enantiodivergent aldehyde addition with β-alkenyl allylic boronates via chiral Brønsted acid catalysis. 2,6-Di-9-anthracenyl-substituted chiral phosphoric acid-catalyzed asymmetric allylation using β-vinyl substituted allylic boronate gave alcohols with R absolute configuration. The sense of asymmetric induction of the catalyst in these reactions is opposite to those in prior reports. Moreover, in the presence of the same acid catalyst, the reactions with β-2-propenyl substituted allylic boronate generated homoallylic alcohol products with S absolute configuration. Unusual substrate-catalyst C-H⋅⋅⋅π interactions in the favoured reaction transition state were identified as the origins of observed enantiodivergence through DFT computational studies.

For more than five decades, P‐stereogenic aminophosphine chalcogenides and boranes have attracted scientific attention and are still in the focus of ongoing research. In the last years, novel transition metal‐based synthesis methods have been discovered, in addition to the long‐known use of chiral auxiliaries. Enantiomerically pure compounds with N−P+−X− (X=O, S, BH3) motifs served as valuable reactive building blocks to provide new classes of organophosphorus derivatives, thereby preserving the stereochemical information at the phosphorus atom. Over the years, intriguing applications in organocatalysis and transition metal catalysis have been reported for some representatives. Asymmetric reductions of C=C, C=N, and C=O double bonds were feasible with selected P‐stereogenic aminophosphine oxides in the presence of hydrogen transfer reagents. P‐stereogenic aminophosphine boranes could be easily deprotected and used as ligands for various transition metals to enable catalytic asymmetric hydrogenations of olefins and imines. This review traces the emergence of a synthetically and catalytically powerful functional compound class with phosphorus‐centered chirality in its main lines, starting from classical approaches to modern synthesis methods to current applications. [ABSTRACT FROM AUTHOR]

The readily available organocatalyst 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) was used for the rapid synthesis of 3‐hydroxyisoindolin‐1‐ones from 3‐alkylidenephthalides. The transformation occurs at room temperature and requires less solvent than traditional methods, providing a more sustainable synthetic option to access 3‐hydroxyisoindolin‐1‐ones with broad scope. Elaboration of the products to diverse scaffolds as well as synthesis of biologically active compounds are demonstrated. [ABSTRACT FROM AUTHOR]

Enzymes and peptide catalysts consist of the same building blocks but require vastly different environments to operate best. Herein, we show that an enzyme and a peptide catalyst can work together in a single reaction vessel to catalyze a two‐step cascade reaction with high chemo‐ and stereoselectivity. Abundant linear alcohols, nitroolefins, an alcohol oxidase, and a tripeptide catalyst provided chiral γ‐nitroaldehydes in aqueous buffer. High yields (up to 92 %) and stereoselectivities (up to 98 % ee) were achieved for the cascade through the rational design of the peptide catalyst and the identification of common reaction conditions. [ABSTRACT FROM AUTHOR]

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]

The design, inspired by the core‐structure of oxicam has allowed the enantioselective synthesis of benzopyranothiazinone motifs employing N‐heterocyclic carbene (NHC) catalysis. The NHC‐mediated transformation involves the reaction of α,β‐unsaturated aldehydes with suitable substituted benzothiazinone derivatives. This process encompasses the initial formation of α,β‐unsaturated acylazoliums from ynals and concurrent generation of enolates from benzothiazinone. The culmination of these reactions results in an efficient annulation, yielding the desired products with reasonable yields and high stereoselectivities. This study underscores the potential of NHC catalysis in the streamlined synthesis of complex heterocyclic structures. [ABSTRACT FROM AUTHOR]

Thioureas catalyze the reaction of phosphonites with in situ‐generated isoquinolinium salts to give C and P‐stereogenic α‐aminophosphinates in high enantioselectivity (up to 96 %) and yield (up to 95 %). Low diastereoselectivity was obtained and this is rationalized in the context of a mechanistic proposal involving anion‐binding catalysis of the P−C bond formation step followed by uncatalyzed Arbuzov collapse. The scope of the reaction, including a g‐scale example, was demonstrated. [ABSTRACT FROM AUTHOR]

δ‐nitro dienes were successfully synthesized and converted to δ‐nitro alkenes with complete chemo and regioselectivity. The enantioselective organocatalytic reduction was also accomplished and afforded the product in up to 97 % e.e. The chiral nitro alkene was further elaborated and employed as starting material in a stereoselective cyclization reaction that led to an almost enantiomerically pure highly functionalised cyclopentane featuring 5 contiguous stereocenters. [ABSTRACT FROM AUTHOR]

A noncovalent organocatalytic concerted addition of phenol to glycal is developed for the stereoselective and regioselective construction of biologically important phenolic 2‐deoxyglycosides, featuring wide substrate tolerance. The method relies on an anion‐bridged dual hydrogen bond interaction which is experimentally proved by Nuclear Magnetic Resonance (NMR), Ultraviolet and visible (UV–vis), and fluorescence analysis. Experimental evidence including kinetic analysis, Kinetic Isotope Effect (KIE) studies, linear free energy relationship, Hammett plot, and density functional theory (DFT) calculations is provided for a concerted mechanism where a high‐energy oxocarbenium ion is not formed. In addition, the potential utility of this method is further demonstrated by the synthesis of biologically active glycosylated flavones. The benchmarking studies demonstrate significant advances in this newly developed method compared to previous approaches. [ABSTRACT FROM AUTHOR]

The 1,4-benzodiazepine structural framework is a fascinating element commonly found in biologically active and pharmaceutically relevant compounds. A highly efficient method for synthesizing 1,4-benzodiazepin-3-ones is described, involving a [4+3]-cycloaddition reaction between 2-amino-β-nitrostyrenes and α-bromohydroxamate, with Cs2CO3 used as a base. This process yielded the desired 1,4-benzodiazepines in good yields. Furthermore, an organocatalytic asymmetric [4+3]-cycloaddition was successfully accomplished using a bifunctional squaramide-based catalyst. This approach enabled the enantioselective synthesis of chiral 1,4-benzodiazepines with commendable yields and moderate enantioselectivities, reaching up to 80% yield and 72% ee. [ABSTRACT FROM AUTHOR]

A designed chiral thiourea‐iminophosphorane catalyst was developed to afford α‐acyloxythioesters through enantioselective acyl‐transfer/protonation of α‐acyloxy‐β‐ketosulfides. The desired reaction proceeded in good yields with high enantioselectivities using a chiral thiourea‐iminophosphorane bearing a pyrrolidine scaffold. [ABSTRACT FROM AUTHOR]

An organocatalytic remote stereocontrolled 1,8‐conjugated addition of in situ formed propargylic aza‐p‐QMs from α‐(4‐aminophenyl) propargylic alcohols and indole‐2‐carboxylates was developed, affording axially chiral tetrasubstituted allenes in 62–99% yield with 52–99% ee. The synthetic strategy not only enriches the chemistry of aza‐p‐quinone methides, but also provides an alternative tool for the preparation of axially chiral tetrasubstituted allenes. [ABSTRACT FROM AUTHOR]

Flavonoids and cannabinoids comprise two large families of natural products that contain a chromane moiety in their structure. Their therapeutic potential has been extensively investigated as potential treatments to several diseases, ranging from cancer to infectious and neurodegenerative diseases. Despite their relative structural simplicity, in recent years creative synthetic methodologies were designed to overcome limitations from the previous synthetic strategies applied to these compounds. The aim of this review is to provide a comprehensive overview of all the enantioselective organocatalytic strategies that have been applied to the synthesis of flavonoids and cannabinoids to date. [ABSTRACT FROM AUTHOR]

A method for the direct asymmetric α-sulfenylation of aldehydes with sulfides was developed. By merging electrochemistry and asymmetric organocatalysis, we obtained α-sulfenylated aldehydes with good to excellent enantioselectivities. Mechanistic investigations indicated a pivotal role of iodine as a catalytic mediator, not only facilitating redox transformations but also possibly contributing to the formation of sulfenyl iodide (RSI) intermediates derived from electrochemically generated disulfides. Our metal-free protocol offers a sustainable and efficient route to access a wide array of α-sulfenylated aldehydes. Remarkably, these transformations take place at room temperature, obviating the need for additional stoichiometric oxidants, thus exemplifying an environmentally friendly and practical synthetic strategy. [ABSTRACT FROM AUTHOR]

This article explores the use of organic photocatalysts (OPCs) in photoredox catalysis, a method for achieving molecular transformations under mild conditions. The authors focus on developing highly reducing OPCs as an alternative to expensive noble-metal-based catalysts. They specifically study small aromatics with two diarylamino termini as OPCs, which have shown promising redox abilities. The article also discusses the applications of these OPCs in regioselective radical fluoroalkylation reactions, which are useful for synthesizing fluorine-containing compounds. The authors investigate different photocatalysts and fluoroalkylating reagents to induce these reactions, highlighting the potential of these sustainable organic synthesis methods. [Extracted from the article]

This article discusses the development of a highly enantioselective synthesis of α-substituted γ-lactones bearing a γ-quaternary stereocenter through catalytic asymmetric bromolactonization. The researchers used chiral bifunctional sulfide catalysts to achieve this synthesis, and they demonstrated the utility of the method through various transformations of the resulting γ-lactone products. The article highlights the importance of these α-substituted γ-lactones as building blocks for the preparation of biologically active compounds. The researchers are currently exploring further applications of their chiral bifunctional sulfide catalysts in other asymmetric syntheses. [Extracted from the article]