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Over the past few years, there has been a surge of interest in the chemistry of bicyclobutanes (BCBs). Although BCBs have been used to synthesize bicyclo[2.1.1]hexanes and bicyclo[3.1.1]heptanes, the synthesis of bicyclo[4.1.1]octanes has remained elusive. Herein, we report the first Lewis acid‐catalyzed unexpected (4+3) annulation of para‐quinonemethides (p‐QMs) with BCBs allowing the synthesis of oxabicyclo[4.1.1]octanes proceeding under mild conditions. With 5 mol % of Bi(OTf)3, the reaction afforded the (4+3) annulated product in high regioselectivity and good functional group compatibility via a simultaneous Lewis acid activation of BCBs and p‐QMs. The reaction is likely initiated by the 1,6‐addition of Lewis acid activated BCBs to p‐QMs followed by the C2‐selective intramolecular addition of the phenol moiety to the generated cyclobutyl cation intermediate. Moreover, detailed mechanistic studies provided insight into the mechanism of the reaction. [ABSTRACT FROM AUTHOR]

The Chemical Communications journal, published by The Royal Society of Chemistry, features articles on various topics such as ionomer performance, catalysis for plastic waste, and multiphase coacervates. The journal also covers research on DNA G-quadruplex targeting molecules, metal-organic cages, and sodium-ion batteries. Additionally, it includes studies on organic photonic heterostructures, spin crossover complexes, and electrochemical nitrate reduction. The articles provide insights into cutting-edge research in the field of chemistry. [Extracted from the article]

The iridium-catalysed enantioselective [3+2] annulation of ortho-ketoarylboron compounds with conjugated dienes proceeded to give chiral indanol derivatives bearing an all-carbon quaternary stereogenic center in high yields with high enantioselectivity. Chiral phosphoramidite–olefin ligands were effective for the high reactivity and enantioselectivity. [ABSTRACT FROM AUTHOR]

Isoindolinones are vital heterocyclic compounds in medicinal chemistry, notable for their diverse bioactivities. Significant attention has been devoted to their preparation; however, existing methods are unsuitable for constructing unsubstituted 3‐methyleneisoindolin‐1‐ones. Herein, we present a rhodium(III)‐catalyzed method for synthesizing unsubstituted 3‐methyleneisoindolin‐1‐ones via C−H/N−H activation and annulation of N‐methoxybenzamides with potassium (ethenyl)trifluoroborate. This approach offers mild reaction conditions, high regioselectivity, and efficient yields. Interestingly, sterically demanding or heterocyclic N‐methoxyaromaticamides resulted in the formation of 2‐vinyl(hetero)aromatic amides instead of 3‐methyleneisoindolin‐1‐ones. Mechanistic insights suggest a rhodacycle intermediate pathway, highlighting the method's potential for developing new bioactive isoindolinone derivatives. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A regiodivergent synthesis of azetidines, 5,6‐dihydro‐1,3‐oxazines and 2,3‐dihydro‐1,4‐oxazines has been achieved through palladium‐catalyzed tandem allylic substitution reaction. This protocol provides a variety of heterocycles in satisfactory yields with good to excellent regioselectivities under mild reaction conditions. [ABSTRACT FROM AUTHOR]

A base promoted oxidative [4+2] annulation of pyrrole‐2‐carbaldehyde derivatives with o‐hydroxyphenyl propargylamines for the synthesis of highly substituted indolizines has been developed. Using DBN as base, a broad range of 5,6,7‐trisubstituted indolizines have been prepared in good to excellent yields under mild conditions, and many useful functional groups can be tolerated. [ABSTRACT FROM AUTHOR]

Density functional theory calculations uncovered a new mechanism for the rhodium-catalyzed decarbonylative annulation of isatoic anhydride with alkynes, in which the acyloxy group formed from the N–H deprotonation and C–O bond cleavage of isatoic anhydride acts as the directing group to assist the ortho C–H activation. From the generated five-membered rhodacycle intermediate, the final aminoisocoumarin product could be formed by subsequent steps of alkyne insertion, reductive elimination, decarbonylation, and protonation. The isocyanate moiety contained in the annulation intermediate was uncovered as a novel internal oxidant for the reaction, which oxidizes the Rh(I) to Rh(III) by decarbonylation. [ABSTRACT FROM AUTHOR]

Organophosphorus compounds have been widely used as achiral and chiral ligands in organic synthesis (PPh3, BINAP, dppe, Duphos, Xantphos, PPFA, Chiraphos, SEGPHOS), flame retardants, functional materials (LED, PV), as well as agrochemicals and medicines due to their broad biological activities. As the privileged versatile building blocks, 1,n‐enynes have been successfully applied in the synthesis of various functionalized cyclic compounds based on their two active unsaturated chemical bonds (C═C double and C≡C triple bonds). With the development of highly selective and efficient methods in organic chemistry, various organophosphorus cyclic compounds synthesis through radical cascade strategy has attracted considerable attention in recent years. In here, we have summarized the recent main achievements in the radical cascade reactions of 1,n‐enynes with phosphorus‐centered radicals. Furthermore, we also displayed the detailed reaction mechanisms in this review. [ABSTRACT FROM AUTHOR]

Phosphine‐mediated one‐pot reactions have been developed that involve two mechanistically distinct reactions assembled in one reaction vessel via the sequential addition process. The first step involves MBH‐type annulation of α,β‐ynones to afford cyclic products in each case, which then engages in subsequent β‐acylation or intramolecular Wittig reactions. The reaction conditions are mild and efficient, providing acylated alkylidene indandiones in 70%–99% yields or furo[2,3‐f]dibenzotropones in 65%–91% yields, respectively. [ABSTRACT FROM AUTHOR]

C−H bond functionalization involving C,C‐palladacycle intermediates provides a unique platform for developing novel reactions. However, the vast majority of studies have been limited to the transformations of C(aryl),C‐palladacycles. In sharp contrast, catalytic reactions involving C(alkyl),C(alkyl)‐palladacycles have rarely been reported. Herein, we disclose an unprecedented cascade C(sp3)−H annulation involving C(alkyl),C(alkyl)‐palladacycles. In this protocol, alkene‐tethered cycloalkenyl bromides undergo intramolecular Heck/C(sp3)−H activation to generate C(alkyl),C(alkyl)‐palladacycles, which can be captured by α‐bromoacrylic acids to afford tricyclic fused pyridinediones. In addition, this strategy can also be applied to indole‐tethered cycloalkenyl bromides to construct pentacyclic fused pyridinediones via suquential Heck dearomatization/C(sp3)−H activation/decarboxylative cyclization. Notably, the removal of α‐bromoacrylic acids in the reaction of alkene‐tethered cycloalkenyl bromides can build an interesting tricyclic skeleton containing a four‐membered ring. Preliminary mechanistic experiments indicate that five‐membered C(alkyl),C(alkyl)‐palladacycles serve as the key intermediates. Meanwhile, density functional theory (DFT) calculations have provided insights into the reaction pathway. [ABSTRACT FROM AUTHOR]

Alkyne annulation represents a versatile and powerful strategy for the assembly of structurally complex compounds. Recent advances successfully enabled electrocatalytic alkyne annulations, significantly expanding the potential applications of this promising technique towards sustainable synthesis. The metallaelectro-catalyzed C–H activation/annulation stands out as a highly efficient approach that leverages electricity, combining the benefits of electrosynthesis with the power of transition-metal catalyzed C–H activation. Particularly attractive is the pairing of the electro-oxidative C–H activation with the valuable hydrogen evolution reaction (HER), thereby addressing the growing demand for green energy solutions. Herein, we provide an overview of the evolution of electrochemical C–H annulations with alkynes for the construction of heterocycles, with a topical focus on the underlying mechanism manifolds. [ABSTRACT FROM AUTHOR]

A general and practical K2CO3-promoted [3+2] annulation between trifluoroacetaldehyde N-triftosylhydrazone (TFHZ-Tfs) and 4-nitroisoxazoles has been developed to access structurally diverse trifluoromethylpyrazolo[3,4-d]isoxazoles. Mechanistically, CF3CHN2 is formed in situ by TFHZ-Tfs decomposition and involves a formal [3+2] dearomative cycloaddition with 4-nitroisoxazoles, followed by aromatization via the elimination of the nitro group. Furthermore, this protocol is metal-free, scalable, mild, and operationally safe, with a broad substrate scope and high functional group compatibility. [ABSTRACT FROM AUTHOR]

Asymmetric de novo synthesis of benzocyclobutenes (BCBs) via catalytic intermolecular reaction is highly desired for efficient access to this important class of compounds, yet such a strategy remains unmet challenge. Here, we report a Pd/Pyrox‐catalyzed asymmetric [2+2] annulation between arylboronic acids and functionalized alkenes, providing an unprecedented efficient protocol to access various enantio‐enriched BCBs in a modular and versatile manner under mild conditions. A broad substrate scope with excellent enantioselectivity has been achieved under the current protocol. The isolation and characterization of the key chiral palladacycle intermediate, together with DFT calculations, provides strong evidence for the catalytic pathway including an enantiodetermining arylpalladation step. [ABSTRACT FROM AUTHOR]

Nucleophilic phosphine-catalyzed annulations are recognized as practical and powerful tools for synthesizing various cyclic compounds. Phosphine acceptors play a key role in nucleophilic phosphine catalysis. The design and synthesis of new phosphine acceptors that are able to introduce new zwitterionic intermediates with new reactivities into phosphine-catalyzed annulations is highly desirable. We recently applied proton-shift principles in the design of new phosphine acceptors, and we synthesized several new acceptors. With the use of these acceptors, we have developed several novel phosphine-catalyzed annulation reactions. In this account, we present a brief introduction to the design and application of a series of acidic-hydrogen-tethered electron-deficient acceptors for phosphine-catalyzed annulation reactions, categorized according to the type of atom (N–H, O–H, C–H) to which the acidic hydrogen is bound. 1 Introduction 2 Phosphine Acceptors Tethered with an Acidic N–H Group 3 Phosphine Acceptors Tethered with an Acidic O–H Group 4 Phosphine Acceptors Tethered with an Acidic C–H Group 5 Conclusions [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis. Described herein is an unusual base‐promoted [4+2] spiroannulation of rarely used isatin‐derived β‐silylcarbinols with o‐halogen aromatic ketones, which enables rapid and modular synthesis of six‐membered carbocyclic spirooxindoles in high yields with excellent functional group tolerance (> 50 examples). Mechanistic experiments revealed that this reaction involved a Peterson olefination, Michael addition and intramolecular C(sp3) arylation cascade. The variegated synthetic derivatization of target products and successful construction of bioactive molecules further illustrate the synthetic potential in spirooxindole‐related drug discovery. [ABSTRACT FROM AUTHOR]

The document from Chemical Communications, published in 2024, provides a comprehensive list of contents for the issue. It includes profiles of contributors, highlights on surface properties of carbon nitride materials, feature articles on various topics such as reactivity, nanoassemblies, and catalysis, as well as communications on topics like intermolecular interactions, synthesis strategies, and catalytic processes. The journal aims to connect the world with the chemical sciences and invest profits back into the chemistry community, reflecting a commitment to advancing research in the field. [Extracted from the article]

Herein, we disclose the hitherto unknown cross-conjugated vinylogous annulation of π-CF3-allyl Pd complexes with 4-methyl-3-trifluoroacetyl-quinolones to access phenanthridones. The CF3 group in the Pd-π-allyl complex is key for exclusive γ-regioselectivity and further annulation. The solvent switch orchestrates the dihydro-phenanthridones (CH3CN) and hydroxy-phenanthridones (DMF) in good yields, and also showed excellent optoelectronic properties. [ABSTRACT FROM AUTHOR]

An effective DABCO‐promoted (4+1) annulation reaction for the synthesis of ethyl (2‐amino‐1H‐pyrrol‐1‐yl)acetate derivatives from 2‐aroyl‐3‐arylcyclopropane‐1,1‐dicarbonitriles and ethyl glycinate was developed. This strategy is characterized by the readily accessible starting materials, mild conditions, and simplicity of operation. [ABSTRACT FROM AUTHOR]

Non‐benzenoid PAHs with pentagon/heptagon pairs have unique electronic structures and promising opto‐electronic properties. However, the construction of pentagon/heptagon pair units in these PAHs is challenging. Herein, we developed a Pd‐catalyzed (3+2) alkyne annulation reaction of heptagons, and constructed heptagon/pentagon pairs. The substrate scope is wide and the yield is good to moderate. A series of dibenzoauzlene derivatives were synthesized and their opto‐electronic properties were systematically studied by UV‐vis absorption and cyclic voltammetry. In addition, the dibenzoazulene derivative was further transformed to tropylium cation and tropyl radical, which showed bathochromic shifted absorption and switched aromaticity. [ABSTRACT FROM AUTHOR]

Cross‐dehydrogenative couplings (CDC) present an efficient strategy for the assembly of biorelevant heterocycles, but are thus far largely limited to toxic transition metals and rather harsh reaction conditions. In sharp contrast, we, herein report on a mild photoelectrocatalyzed CDC‐[4+2] annulation enabling the synthesis of functionalized isothiochromenes enabled by a proton‐coupled electron transfer (PCET) strategy. The transformative photoelectrocatalysis obviated toxic transition‐metal, high reaction temperatures, and stoichiometric chemical redox reagents. This approach was characterized by exceedingly mild conditions, ample substrate scope, and a commercially available catalyst. Gram‐scale reactions and a telescoped synthesis route reflected the unique potential in the green synthesis of important S‐heterocycles. [ABSTRACT FROM AUTHOR]

The first synthesis of 3,4-diarylpyrimido[1,2-b]indazole derivatives from 3-aminoindazoles has been realized. The FeCl3-catalyzed intermolecular epoxide ring-opening reaction altered the order of annulation, with the free primary NH2 groups in 3-aminoindazoles preferentially reacting with styrene oxides instead of aromatic aldehydes. This protocol is further highlighted by its broad substrate compatibility, high chemo- and regioselectivities, and the late-stage modifications of bioactive molecules. Without aromatic aldehydes, the synthesis of 3-aryl-4-acylpyrimido[1,2-b]indazole derivatives can also be accomplished using alternative reaction conditions. [ABSTRACT FROM AUTHOR]

Despite the preliminary success of transition metal‐catalyzed [3+2] annulation of amides with olefins, the corresponding radical‐type [3+2] annulation remains a laborious challenge. Herein we report the first photoredox‐catalyzed radical‐type [3+2] annulation of aromatic amides with olefins. We established an approach to generate unprecedented iminium radicals by reducing the oxyiminium intermediates, formed in situ from corresponding amides with Tf2O, via photoredox catalysis. The [3+2] annulation was achieved via stepwise radical process, instead of forming linear products via other pathways as previously reported. This annulation protocol exhibits excellent functional group tolerance, and a diversity of substrates are united under the photoredox conditions, affording iminium products that can be in situ diversified into 1‐indanones, enamines and amines. Mechanistic investigations indicate reduction of the oxyiminium intermediate to the iminium radicals by excited‐state of the photocatalyst initiates the catalytic cycle. [ABSTRACT FROM AUTHOR]

The first Ficini reaction between ynamides and acrylates is reported herein. The reaction is catalyzed by B(C6F5)3 acting as a Lewis acid and is giving access to stable tri‐substituted aminocyclobutenes in high yield. The resulting products can be hydrogenated and epimerized under basic conditions or in presence of a Lewis acid, providing two distinct trans‐ aminocyclobutane monoester stereoisomers in high yield and diastereoisomeric ratio (up to quantitative yield and >99 : 1 dr). [ABSTRACT FROM AUTHOR]

The document from Chemical Communications, published in 2024, provides a comprehensive list of articles covering various topics in chemistry. It includes research on electrochemical deconstructive functionalization, organoboron catalysis, recent progress in sensing technologies, and advancements in metal carbene-induced rearrangements. The journal aims to uncover new possibilities through original discoveries and fundamental questions in the field of chemistry. [Extracted from the article]

Herein, we have described a novel organocatalytic approach to access biologically important dihydropyridin-2-ones in a one-pot way with generally high yields (up to 99%) and excellent enantioselectivities (up to 99% ee). This reaction proceeded via a new dual activation mode, including in situ-generated α,β-unsaturated acylazoliums and 4-dimethylaminopyridinium salts that underwent a Michael addition/1,4-H migration/lactamization sequence. The base-triggered 4-dimethylaminopyridinium ylide formation pathway over the competing substitution reaction pathway of vicinal haloamines is noteworthy. [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]

An efficient methodology for the synthesis of highly diverse 4-aminoquinoline derivatives from activated alkynes and 2-aminobenzonitriles mediated by Lewis acid is described. The reaction proceeds via sequential aza-Michael addition/intramolecular annulation to afford highly substituted 4-aminoquinolines in good yields. The reaction is operationally simple and has high atom-economy with broad substrate scope. The post synthetic application of the reaction provides 4 H -benzo[ de ][1,6]naphthyridines. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel [4+2] annulation reaction between o‐acylamino‐aryl MBH carbonates and isatylidene malononitriles has been successfully developed. This methodology exhibits excellent substrate tolerance, affording a series of spiro[indolin‐3,2′‐quinoline] framework compounds with yields up to 98%. The scalability of the reaction is also noteworthy, as evidenced by the 95% yield of the final product upon a 50‐fold scale‐up. [ABSTRACT FROM AUTHOR]

The synthesis of substituted 3‐oxo‐pyrimido[1,2‐b]indazoles from 3‐aminoindazoles and ketones has been established. It involves one molecule of 3‐aminoindazoles and two molecules of ketones via a [3+2+1] three‐component annulation process. 3‐Oxo‐pyrimido[1,2‐b]indazoles exhibit strong yellow fluorescence in various solvents. A wide range of products have anti‐oxidant activities. Cytotoxicity studies indicate that compounds 3 a, 3 aa and 3 ab have obvious effects on both HCT116 and A549 cancer cell lines. [ABSTRACT FROM AUTHOR]

A copper‐catalyzed annulation of enaminones with maleimides was developed to synthesize various pyrrolo[3,4‐e]isoindoles. In this strategy, 2‐aminopyridine served as a traceless directing group, and target products were obtained in 54–72% yields. Moreover, a plausible mechanism for this reaction was proposed based on several control experiments, deuterium exchange experiments, and previous reports. [ABSTRACT FROM AUTHOR]

A method for synthesizing pyrimido[1,2‐a]indol‐4‐ol heteroarenes via a Cp*Rh(III)‐catalyzed cascade C−H activation/annulation strategy employing N‐methoxyindoleamides and isoxazolones is developed. Also, a framework of 3‐methoxy‐2,3‐dihydro‐[1,3,5]triazino[1,2‐a]indole‐4,10‐dione was successfully synthesized via a Cp*Rh‐catalyzed C−H activation/annulation/oxidation reaction between N‐(methyloxy)‐1H‐indole‐1‐carboxamide and isoxazolones. These reactions demonstrated the suitability of several substrates, compatibility with numerous functional groups, and mild reaction conditions. Preliminary mechanistic investigations have been completed. [ABSTRACT FROM AUTHOR]

ABSTRACT A practical and straightforward strategy for the synthesis of ferrocene appended furopyranone, furochromenone, and benzofuranone via a metal‐free annulation reaction of imidazolium ylide with enone mediated by saccharin‐based ionic liquid has been reported. The mechanistic studies show an approach through synergistic dual activation of enone and imidazolium ylide via cation and anion of ionic liquid, respectively. This operationally simple protocol offers an easy and rapid access to a library of ferrocene appended furopyranone, furochromenone, and benzofuranone in moderate to good yields through the involvement of a six‐membered transition state. [ABSTRACT FROM AUTHOR]

Benzoheteroles are promising structural scaffolds in the realm of medicinal chemistry, but sustainable synthesis of 2,3‐difunctionalized benzoheterole derivatives is still in high demand. Indeed, we have conceptually rationalized the intrinsic reactivity of propargylic‐enyne systems for the flexible construction of 2,3‐disubstituted benzoheteroles through radical sulfonylative‐cyclization cascade under organophotoredox catalysis. We hereby report an efficient visible‐light‐induced sulfonyl radical‐triggered cyclization of 1,6‐enynols with sulfinic acids under the dual catalytic influence of 4CzIPN and NiBr2⋅DME, which led to the formation of 2,3‐disubstituted benzoheteroles in good to high yields. Additionally, the Rose Bengal (RB)‐catalyzed radical sulfonylative‐cycloannulation of acetyl‐derived 1,6‐enynols with sulfinic acids under blue LED irradiation allowed to access 3‐(E‐styryl)‐derived benzofurans and benzothiophenes in moderate to good yields. The scope and limitations of the present strategies were successfully established using different classes of 1,6‐enynols and sulfinic acids bearing various sensitive functional groups, yielding the desired products in a highly stereoselective fashion. Plausible mechanistic pathways were also proposed based on the current experimental and control experiments. [ABSTRACT FROM AUTHOR]

A catalyst‐based switchable regioselective C−H activation/annulation of acrylamides with propargyl carbonates has been developed, delivering C5 or C6 alkenyl substituted 2‐pyridones. This robust protocol proceeds with a broad substrate scope and good functional group tolerance under redox‐neutral reaction conditions. More significantly, this reaction is highly effective with previously challenging unsymmetrical alkynes, including unbiased alkyl‐alkyl substituted alkynes, with perfect and switchable regioselectivity. Additionally, mechanistic studies and DFT calculations were performed to shed light on the switchable regioselectivity. [ABSTRACT FROM AUTHOR]

A KOtBu‐promoted robust strategy has been described for the regioselective synthesis of pyrrolo[3,4‐b]quinolin‐1‐one and naphthyridin‐1(2H)‐one derivatives from o‐alkynylquinolinecarbonitriles in good to excellent yields. The reaction proceeds through in situ transformation of the nitrile moiety into an amide group followed by the selective C−N bond formation through a 5‐exo‐dig or 6‐endo‐dig annulation reaction. Among the synthesized derivatives, 6‐endo‐dig naphthyridin‐1(2H)‐ones displayed good photophysical properties. The present approach is superior to other established methodologies as it avoids use of transition metals and column chromatographic purification and affords the products in high yields. Additionally, the current methodology provides several additional advantages, such as one‐pot operation, high atom economy, broad substrate scope and a step‐economical process. [ABSTRACT FROM AUTHOR]

Low‐energy light, endowing with excellent characteristics of lower energy, fewer side reactions, more abundance in solar light. The scenario has been developed for the fabrication of indenone through a low‐energy green light driven radical annulation reaction between α‐keto acids and internal alkynes using Rhodamine 6G as photocatalyst. Various kinds of substrates are suitable for this methodology, affording the corresponding indenones in a greener and efficient manner. [ABSTRACT FROM AUTHOR]

An achiral Cp*Co(III)‐catalyzed enantioselective C−H activation/annulation of chiral sulfoximine‐enabled thioamides with ynamides is presented herein. This method successfully synthesizes axially chiral five‐membered 2‐amidoindenones with good enantiocontrol. Interestingly, the annulation with chiral oxazolidone‐containing ynamides could provide a separable mixture of diastereomers (up to ~10 : 1 dr). Moreover, enantiopure sulfoximines could be recovered with ~99 % purity, making this method practical. DFT studies show valuable insight into the mechanism and origin of asymmetric induction. [ABSTRACT FROM AUTHOR]

Inherently chiral medium-ring derivatives have important applications in many research fields, such as materials science, molecular recognition, and asymmetric catalysis. However, the enantioselective assembly of these molecules, especially by organocatalytic strategies, remains a formidable challenge, and few methods are available. Here, we report the enantioselective NHC-catalyzed (NHC: N-heterocyclic carbenes) formal high-order (5 + 3) annulation of 1-(2-indolyl)naphthalen-2-ols with ynals. In the presence of an NHC pre-catalyst, base, Lewis acid and oxidant, this protocol enables the catalytic formation of C–C and C-O bonds, providing practical and facile access to an array of inherently chiral saddle-shaped eight-membered lactones featuring an oxocin-2-one scaffold with structural diversity in good efficiency and excellent enantiocontrol. Moreover, the scale-up preparation and representative late-stage transformations of the eight-membered lactones further demonstrate the application potential of this synthetic technology. Inherently chiral medium-ring derivatives have important applications in many research fields, but few enantioselective methods are available. Herein, the authors report the enantioselective N-heterocyclic carbenes-catalyzed formal (5 + 3) annulation of 1-(2-indolyl)naphthalen-2-ols with ynals for the synthesis of eight-membered lactones. [ABSTRACT FROM AUTHOR]

A highly efficient cascade aza‐MIRC (Michael Induced Ring Closure) reaction between trifluoromethylpyrazole (TFPZ)‐derived oxadienes and a‐bromohydroxamates has been developed for the construction of 1,4‐oxazepinone derivatives. The reaction proceeds smoothly under mild conditions via a cascade Aza‐Michael addition/intramolecular SN2 sequence, and features broad substrate scope, transition‐metal free, operational simplicity etc. The utility of the versatile protocol was also demonstrated by gram‐scale reaction and valuable synthetic transformations. [ABSTRACT FROM AUTHOR]

The document is the contents list for an issue of the journal Chemical Communications. It includes various articles and communications on topics such as biocatalysis, stereochemistry of natural products, enzyme design, coordination-cage based catalysis, and more. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The document provides a glimpse into the research and advancements in the field of chemistry. [Extracted from the article]

The one‐step synthesis of tetra‐substituted benzenes was accomplished via gold‐catalyzed diyne‐ene annulation. Distinguished from prior modification methods, this novel strategy undergoes formal [3+3] cyclization, producing polysubstituted benzenes with exceptional efficiency. The critical factor enabling this transformation was the introduction of amides, which were reported for the first time in gold catalysis as covalent nucleophilic co‐catalysts. This interesting protocol not only offers a new strategy to achieve functional benzenes with high efficiency, but also enlightens potential new reaction pathways within gold‐catalyzed alkyne activation processes. [ABSTRACT FROM AUTHOR]

The syntheses of novel spirobenzazepinoindole derivatives has been achieved through a highly efficient and synthetic route. The approach involves a two‐step reaction, utilizing indole derivatives, 2‐amino benzyl alcohol, and ninhydrin as key starting materials under mild reaction conditions. The reaction proceeds via a sequential cascade process involving cyclization, condensation and spiro‐annulation, leading to the formation of the spirobenzazepinoindole core structure in good to excellent yields. The method offers broad substrate scope, high atom economy, and operational simplicity. The synthesized spirobenzazepinoindoles were fully characterized by spectroscopic techniques, including NMR (1H & 13C), IR and mass spectrometry. The methodology provides a valuable tool for the rapid generation of structurally complex spirobenzazepinoindoles, which could serve as scaffolds for the development of new therapeutic agents. [ABSTRACT FROM AUTHOR]

An efficient chalcogenative annulation strategy for constructing functionalized saturated N-heterocycles from unactivated alkenes with dichalcogenides under electrochemical conditions has been presented. This protocol is applicable to mono-, di- or tri-substituted alkenes, providing a straightforward pathway to aziridines, azetidines, pyrrolidines, and piperidines with high regioselectivity. Moreover, the strategy is qualified to realize the oxychalcogenation of alkenes as well. [ABSTRACT FROM AUTHOR]

Macrocycles are essential in protein‐protein interactions and the preferential intake of bioactive scaffolds. Macrocycles are commonly synthesized by late‐stage macrolactonizations, macrolactamizations, transition metal‐catalyzed ring‐closing metathesis, S−S bond‐forming reactions, and copper‐catalyzed alkyne–azide cycloaddition. Recently, transition metal‐catalyzed C−H activation strategies have gained significant interest among chemists to synthesize macrocycles. This article provides a comprehensive overview of the transition metal‐catalyzed macrocyclization via C−H bond functionalization of heterocycle‐containing peptides, annulations, and heterocycle‐ring construction through direct C−H bond functionalization. In the first part, palladium salt catalyzed coupling with indolyl C(sp3)−H and C(sp2)−H bonds for macrocyclization is reported. The second part summarizes rhodium‐catalyzed macrocyclizations via site‐selective C−H bond functionalization. Earth‐abundant, less toxic 3d metal salt Mn‐catalyzed cyclizations are reported in the latter part. This summary is expected to spark interest in emerging methods of macrocycle production among organic synthesis and chemical biology practitioners, helping to develop the discipline. We hope that this mini‐review will also inspire synthetic chemists to explore new and broadly applicable C−C bond‐forming strategies for macrocyclization via intramolecular C−H activation. [ABSTRACT FROM AUTHOR]

A synthesis of benzo[d]oxazoles by an N-deprotonation–O-SNAr cyclization sequence from anilide precursors is reported. Anilides derived from 2-fluorobenzaldehydes, activated toward SNAr ring closure by C5 electron-withdrawing groups, were prepared and subjected to deprotonation–cyclization using 2 equiv. of K2CO3 in anhydrous DMF. Following deprotonation at nitrogen, the delocalized anion cyclized from the amide oxygen to give high yields of benzo[d]oxazoles. The temperature required for the cyclization of benzanilides correlated with the potency of the C5 activating group on the SNAr acceptor ring with nitro (most potent) reacting at 90 °C (1 h), cyano reacting at 115 °C (1 h), methoxycarbonyl reacting at 120 °C (2 h), and trifluoromethyl (least potent) reacting at 130 °C (3 h). Acetanilides were more difficult to cyclize but generally required 4–6 h at these same temperatures for completion. Product purification was accomplished by recrystallization or chromatography. [ABSTRACT FROM AUTHOR]

With triethylamine as a synthon, an alternative method for the synthesis of 3‐formyl imidazo[1,2‐a]pyridines has been accomplished from aldehydes, and 2‐aminopyridines. The reaction proceeded via iodine‐catalyzed C−N bond cleavage of triethylamine, generation of α,β‐unsaturated aldehyde in situ, and oxidative cyclization with air as the oxygen source. This protocol may facilitate the synthesis of imidazo[1,2‐a]pyridine derivatives and provide a reference for the usage of triethylamine as a synthon. [ABSTRACT FROM AUTHOR]

A new strategy for thiochromen‐4‐one synthesis that relies on the denitrative formal [5+1] cycloaddition of 1‐(2‐nitrophenyl)‐2‐yn‐1‐ones with thioacetamide is described. Achieved under reaction conditions that did not require transition metal catalysis, nor the exclusion of air or moisture, the reaction is suggested to involve exploiting the propensity of thioacetamide to undergo hydrolysis under basic conditions. This is follows by addition of the ensuing sulfide anion to the 1,3‐alkynone and a nucleophilic aromatic substitution and denitrative rearomatization cascade to give the S‐heterocyclic product in yields of 41–99 %. [ABSTRACT FROM AUTHOR]

Pyridazine is a significant skeleton that widely exists in drugs and bioactive molecules. We herein describe expeditious approaches to access polysubstituted pyridazines from readily accessible unactivated ketones and acylhydrazones via Cu-promoted C(sp3)–C(sp3) coupling/cyclization sequences in a single-step fashion. Notably, the disparate 3,4,6-trisubstituted pyridazines and 3,5-disubstituted pyridazines could be obtained by tailoring the ketone's structure and reaction conditions. These transformations feature good functional group compatibility, excellent step-economy, and chemoselectivity. The potential synthetic utility of these conversions is illustrated by scale-up reactions and late-stage derivatizations of the as-prepared pyridazine products. [ABSTRACT FROM AUTHOR]

Inherently chiral calixarenes have garnered significant attention due to their distinctive properties, yet the development of efficient catalytic asymmetric synthesis methods remains a critical challenge. Herein, we report the asymmetric synthesis of calix[4]arenes featuring inherent or both inherent and axial chirality via a cobalt‐catalyzed C−H activation/annulation strategy in high yield with excellent enantio‐ and diastereoselectivity (up to >99 % ee and >20 : 1 dr). Electrooxidation was also suitable for this transformation to obviate the sacrificial metal oxidants, underscoring the environmentally friendly potential of this approach. A key octahedral cobaltacycle intermediate was synthesized and characterized, providing valuable insights into the mode of enantio‐ and diastereocontrol of this protocol. Noteworthy photoluminescence quantum yields of up to 0.94 were measured, underscoring the potential of these compounds in the domain of organic fluorescent materials. [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]