Search

Peripheral editing of complex molecules via C−H functionalization removes the pervasive retrosynthetic bias toward pre‐functionalization and taps into the innate, often subtle, stereoelectronic differences between C−H linkages. Using this approach, bioactive molecules and residues can be modified without being beholden to lengthy sequences, thus allowing biochemical hypotheses to be interrogated on accelerated timelines. Herein, the C−H functionalization paradigm is leveraged to tackle C7 C−H functionalization of the biologically important tryptophan core. The devised process, which was expanded to indolyl (and related) systems, utilizes an N‐bound unsymmetrical "designer" phosphine to direct C−H functionalization to the desired position while maintaining operational ease of directing group installation/removal. Quantum mechanically calculated steric properties and activation free energies suggest that this phosphine is hindered enough for favoring C−H functionalization over deactivation pathways but is still easily cleaved by nucleophiles. In addition, the process enables the direct C−H methylation, cyclopropanation, and arylation of tryptophan to yield unnatural amino acid (UAA) building blocks. As a testament to the versatility of this method, a solid phase peptide synthesis (SPPS)‐ready phosphinated tryptophan was incorporated into a pentapeptide and the C−H functionalization/dephosphination sequence was executed with ease. The utility of "on‐peptide" editing was exhibited through the late‐stage functionalization of several pentapeptides with a diverse set of C7 substituents on‐ and off‐resin. [ABSTRACT FROM AUTHOR]

A Cp*Ir‐catalyzed C−H arylation of 1‐isoquinolinone and 2‐pyridones with N‐2‐pyridyl as a directing group to afford 6‐phenylpyridin‐2(1H)‐ones and 3‐phenylisoquinolin‐1(2H)‐ones by using arylsilanes is described in this paper. This method tolerates a series of functional groups, such as halide, trifluoromethyl, C=C double bond and offers a synthetic approach to the core structure of protoberberine alkaloids. Several experiments on mechanism studies were conducted to reveal the possible process of this Cp*Ir‐catalytic cycle. [ABSTRACT FROM AUTHOR]

Stereoselective construction of g- and d-stereocenters in carbonyl compounds is a pivotal objective in asymmetric synthesis. Here, we report chiral bifunctional oxazoline-pyridone ligands that enable enantioselective palladium-catalyzed remote g-C−H (hetero)arylations of free cycloalkane carboxylic acids, which are essential carbocyclic building blocks in organic synthesis. The reaction establishes g-tertiary and a-quaternary stereocenters simultaneously in up to >99% enantiomeric excess, providing access to a wide range of cyclic chiral synthons and bioactive molecules. The sequential enantioselective editing of two methylene C-H bonds can be achieved by using chiral ligands with opposite configuration to construct carbocycles containing three chiral centers. Enantioselective remote d-C−H (hetero)arylation is also realized to establish d-stereocenters that are particularly challenging to access using classical methodologies. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of alkyl aryl ethers using diaryliodonium salts. Alkyl aryl ethers are commonly found in pharmaceuticals, agrochemicals, and functional materials. The authors propose a new method using main-group mediators to overcome the limitations of current synthetic strategies. They conducted experiments to identify the scope and limitations of the reaction and discuss the mechanistic implications of their findings, including the potential formation of arynes and the oxidation of alcohols. The article also explores the development of a method for O-arylation of aliphatic alcohols using aryl(TMP)iodonium salts, which is compatible with various types of alcohols and aryl groups. The authors conducted experiments to understand the mechanisms involved and ruled out certain background reactions. They observed the formation of aryne intermediates in some reactions but concluded that arynes are unlikely to mediate the oxidation of benzyl alcohol under the given conditions. [Extracted from the article]

Methyl 4-(1,3a,6a-triazapentalen-3-yl)benzoate (TAP1) shows interesting properties as a small molecule fluorophore. In the search for post-functionalization methods, palladium-catalyzed arylation reactions were demonstrated. Direct CH arylation reactions of TAP1 with various aryl halides resulted in 3,6-diaryltriazapentalenes TAP4, although mostly in poor yields. Bromination of TAP1 followed by Suzuki coupling, on the other hand, requires a more delicate procedure, but gave arylated products with the same regiochemistry (TAP4) in moderate to good yields. The structure of 6-phenyltriazapentalene TAP4a was confirmed by crystallographic analysis. In addition, the effect of the C6 arylation on the fluorescent properties of 3-aryl-1,3a,6a-triazapentalenes was studied in dichloromethane at room temperature and in 2-methyltetrahydrofuran at 77 K, while the photophysical properties of two saponified derivatives were measured in acetonitrile. [ABSTRACT FROM AUTHOR]

A C–H arylation of thiopyran derivatives with aryl halides has been developed. Under the catalysis of Pd(OAc)2/Ag2CO3, the C–H arylation takes place at the α-position of the thiopyran ring. When dibromo-substituted compounds are used as reactants, double C–H arylations may occur on the same thiopyran ring at its α- and β-positions. [ABSTRACT FROM AUTHOR]

Aryl diazonium salts are versatile compounds known for their reactivity in various transformations. In this study, we explored the arylation of 3‐methylene isoindolinones using aryl diazonium salts. The objective was to develop a method for accessing 3‐benzyl‐3‐methoxyisoindolin‐1‐ones, a class of compounds with diverse biological activities and synthetic importance. Optimization of the reaction conditions revealed the significance of light irradiation for improved yields. The substrate scope investigation demonstrated the compatibility of various diazonium salts and N‐substituents on the 3‐methylene isoindolinone scaffold, yielding the corresponding methoxy lactams with high yields. Mechanistic insights were obtained by observing the effect of base and light irradiation. Two initiation mechanisms were proposed: in the presence of a base, the reaction could proceed even without light irradiation, while light irradiation was necessary in the absence of a base. DFT calculations were performed to elucidate the mechanism of the reaction and provide energetic considerations [ABSTRACT FROM AUTHOR]

Charge‐programmed 3D printing enables the fabrication of 3D electronics with lightweight and high precision via selective patterning of metals. This selective metal deposition is catalyzed by Pd nanoparticles that are specifically immobilized onto the charged surface and promises to fabricate a myriad of complex electronic devices with self‐sensing, actuation, and structural elements assembled in a designed 3D layout. However, the achievable property space and the material‐performance correlation of the charge‐programmed printing remain unexplored. Herein, a series of photo‐curable resins are designed for unveiling how the charge and crosslink densities synergistically impact the nanocatalyst‐guided selective deposition in catalytic efficiency and properties of the 3D printed charge‐programmed architectures, leading to high‐quality 3D patterning of solid and liquid metals. The findings offer a wide tunability of the structural properties of the printed electronics, ranging from stiff to extreme flexibility. Capitalizing on these results, the printing and successful application of an ultralight‐weight and deployable 3D multi‐layer antenna system operating at an ultrahigh‐frequency of 19 GHz are demonstrated. [ABSTRACT FROM AUTHOR]

Although the 3 d transition‐metal catalyzed C−H functionalization have been extensively employed to promote the formation of valuable carbon‐carbon bonds, the persistent problems, including the use of sensitive Grignard reagents and the rigorous operations (solvent‐drying, inert gas protection, metal pre‐activation and RMgX addition rate control), still leave great room for further development of sustainable methodologies. Herein, we report a mechanochemical technology toward in‐situ preparation of highly sensitive organomagnesium reagents, and thus building two general 3 d transition‐metal catalytic platforms that enables regioselective arylation and alkylation of indoles with a wide variety of halides (including those containing post transformable functionalities and heteroaromatic rings). This mechanochemical strategy also brings unique reactivity and high step‐economy in producing functionalized N‐free indole products. [ABSTRACT FROM AUTHOR]

Non‐directed C−H arylation is one of the most efficient methods to synthesize biaryl compounds without the need of the prefuctionalization of starting materials, or the installment and removal of directing groups on the substrate. A direct C−H arylation of simple arenes as limiting reactants remains a challenge. Here we disclose a non‐directed C−H arylation of anisole derivatives as limiting reagents with aryl iodides under mild reaction conditions. The arylated products are obtained in synthetically useful yields and the arylation of bioactive molecules is also demonstrated. Key to the success of this methodology is the use of a one‐step synthesized S,O‐ligand. [ABSTRACT FROM AUTHOR]

High ambipolar mobility emissive conjugated polymers (HAME‐CPs) are perfect candidates for organic optoelectronic devices, such as polymer light emitting transistors. However, due to intrinsic trade‐off relationship between high ambipolar mobility and strong solid‐state luminescence, the development of HAME‐CPs suffers from high structural and synthetic complexity. Herein, a universal design principle and simple synthetic approach for HAME‐CPs are developed. A series of simple non‐fused polymers composed of charge transfer units, π bridges and emissive units are synthesized via a two‐step microwave assisted C−H arylation and direct arylation polymerization protocol with high total yields up to 61 %. The synthetic protocol is verified valid among 7 monomers and 8 polymers. Most importantly, all 8 conjugated polymers have strong solid‐state emission with high photoluminescence quantum yields up to 24 %. Furthermore, 4 polymers exhibit high ambipolar field effect mobility up to 10−2 cm2 V−1 s−1, and can be used in multifunctional optoelectronic devices. This work opens a new avenue for developing HAME‐CPs by efficient synthesis and rational design. [ABSTRACT FROM AUTHOR]

Molecules containing ether skeletons are widely present in drugs, natural products, functional materials, and life science. Direct C(sp3)−H bond ether functionalization is considered a powerful strategy for the construction of novel ether derivatives. Photo‐/electro‐chemical technology is a relatively green and sustainable synthesis method, which opens up a broad application prospect in the field of direct functionalization of C(sp3)−H bonds. In recent years, photo‐/electro‐mediated C(sp3)−H bond alkylation, arylation, alkynylation, esterification, mercaptoylation, sulfidation, and amination of ethers have been extensively studied. In this review, the research progress of photo‐/electro‐mediated C(sp3)−H bond functionalization of ether compounds from 2014 to 2023 is systematically reviewed, and the scope, limitations, and mechanisms for some reactions are discussed. [ABSTRACT FROM AUTHOR]

C–H arylation of heterocyclic compounds is a very interesting and important research field in chemistry for the formation of C–C bonds, but unfortunately, few methods have been reported for this purpose. In this attractive and highly efficient methodology, we wish to report that copper (I) chloride immobilized on magnetic nanoparticles modified with benzothiazole-pyrimidine Ligand (Fe3O4@BTH-Pyr-CuCl) is a novel and efficient magnetically recoverable catalyst for carbon–carbon bond formation through C–H arylation of a category of heterocyclic compounds by aryl iodides in the presence of KOAc in PEG under mild conditions. Under this catalytic system, A category of heterocyclic substrates including benzo[d]oxazole, benzo[d]thiazole, 1-methyl-1H-benzo[d]imidazole, 2,5-diphenyloxazole, benzofuran, 2-phenyl-1,3,4-oxadiazole and 2-phenylimidazo[1,2-a]pyridine were used as substrate and the desired products were prepared with high to excellent yields. Reusability tests revealed that the Fe3O4@BTH-Pyr-CuCl catalyst can be reused at least 7 runs without significant decrease in its catalytic efficiency. ICP-OES, VSM and SEM techniques confirmed the recovered Fe3O4@BTH-Pyr-CuCl catalyst was very stable and had high magnetic property despite the utilization for 7 runs. [ABSTRACT FROM AUTHOR]

This mini review article provides an overview on the use of hypervalent iodine compounds (HICs) in carbohydrate synthesis, focusing on their chemistry and recent applications. HICs are similar to transition metals in their reactivity but have the added benefit of being environmentally benign, and are therefore commonly used as selective oxidants and eco‐friendly reagents in organic synthesis. Herein, we summarize various synthetic uses of hypervalent iodine reagents in reactions such as glycosylation, oxidations, functionalization, and C−C bond‐forming reactions. The goal of this review is to illustrate the advantages and versatility of using HICs as an environmentally sustainable alternative to heavy metals in carbohydrate chemistry. [ABSTRACT FROM AUTHOR]

An unprecedented silver‐mediated intramolecular oxy‐argentation of 3‐amidoaryne precursors that quickly generates a heteroarylsilver species is developed. AgF acts as both a stoichiometric fluoride source and a reagent for the formation of a benzoxazolylsilver intermediate via aryne generation. Pd‐catalyzed coupling reactions of (hetero)aryl iodides with a silver species, generated in situ, allow for the synthesis of various C7‐arylated benzoxazoles. As a result, an aryl group is selectively introduced into the meta‐position of 3‐amidobenzyne precursors. Mechanistic studies have indicated the presence of a benzoxazolylsilver intermediate and revealed that the reaction proceeds via an intramolecular oxy‐argentation process, which is initiated by a direct fluoride attack on the silyl group. [ABSTRACT FROM AUTHOR]

An efficient Rh(II)-catalyzed highly selective N2-arylation of benzotriazole, indazole, and 1,2,3 triazole is developed using diazonaphthoquinone. The developed protocol is extended with a wide scope. In addition, late-stage arylation of these scaffolds tethered with bioactive molecules is explored. Control experiments and DFT calculations reveal that the reaction proceeds presumably via nucleophilic addition of the N2 (of the 1H tautomer) center to quinoid-carbene followed by a 1,5-H shift. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Electrochemistry is the property of Journal of Electrochemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phenolic biaryl and styryl moieties are important structural motifs in natural products, pharmaceuticals, and functional materials. Traditional cross‐coupling often requires pre‐functional substrates and is accompanied by generation of organometallic by‐products. In recent years, diazo quinone has become a new type of high‐efficiency phenolic coupling reagent for the preparation of phenolic biaryl and styryl compounds. This is because it can be used to construct C(sp2)−C(sp2) bonds in an environment‐friendly (transition‐metal‐free) or more direct way. In this review, we focus on recent advances in the field of transition‐metal‐free cross‐coupling reactions of diazo quinones with organoboranes and transition‐metal catalyzed quinoid carbene C(sp2)−H arylation reactions. [ABSTRACT FROM AUTHOR]

Rh(I)‐catalyzed C8‐selective C−H alkenylation and arylation of 1,2,3,4‐tetrahydroquinolines with alkenyl and aryl carboxylic acids under microwave assistance have been realized. Using [Rh(CO)2(acac)] as the catalyst and Piv2O as the acid activator, 1,2,3,4‐tetrahydroquinolines undergo C8‐selective decarbonylative C−H alkenylation with a wide range of alkenyl and aryl carboxylic acids, affording the C8‐alkenylated or arylated 1,2,3,4‐tetrahydroquinolines. This method enables the synthesis of C8‐alkenylated 1,2,3,4‐tetrahydroquinolines that would otherwise be difficult to access by means of conventional C−H alkenylation protocols. Moreover, this catalytic system also works well in C8‐selective decarbonylative C−H arylation of 1,2,3,4‐tetrahydroquinolines with aryl carboxylic acids. The catalytic activity strongly depends on the choice of the N‐directing group, with the readily installable and removable N‐(2‐pyrimidyl) group being optimal. The catalytic pathway is elucidated by mechanistic experiments. [ABSTRACT FROM AUTHOR]

An efficient asymmetric remote arylation of C(sp3)−H bonds under photoredox conditions is described here. The reaction features the addition radicals to a double bond followed by a site‐selective radical translocation (1,n‐hydrogen atom transfer) as well as a stereocontrolled aryl migration via sulfinyl‐Smiles rearrangement furnishing a wide range of chiral α‐arylated amides with up to >99 : 1 er. Mechanistic studies indicate that the sulfinamide group governs the stereochemistry of the product with the aryl migration being the rate determining step preceded by a kinetically favored 1,n‐HAT process. [ABSTRACT FROM AUTHOR]

Complementary to the design of a single structurally complex chiral ligand to promote each step in transition‐metal catalysis, multiligand relay catalysis through dynamic ligand exchange with each step in the catalytic cycle promoted by its best ligand provides an attractive approach to enhance the whole reaction reactivity and selectivity. Herein, a regio‐ and enantioselective NiH‐catalyzed migratory hydroarylation process with a simple combination of a chain‐walking ligand and an asymmetric arylation ligand, producing high‐value chiral α‐(hetero)aryl‐substituted amines and their derivatives under mild conditions, is reported. The potential synthetic applications of this transformation are demonstrated by the concise synthesis of (S)‐nicotine and a CDK8 inhibitor. [ABSTRACT FROM AUTHOR]

A CuInS2 quantum dot-modified K-C3N4 Z-scheme heterojunction was designed and synthesized. The structure and composition of CuInS2/K-C3N4 were well characterized. The arylation of heteroarenes with aryl diazonium salts driven by a heterogeneous CuInS2/K-C3N4 catalytic system was established under visible light irradiation in water for the first time. A variety of arylated heteroarenes were synthesized in high yields with commendable functional group tolerance. The designed CuInS2/K-C3N4 photocatalyst can be recycled and reused several times without significantly reducing its catalytic activity. [ABSTRACT FROM AUTHOR]

A C(sp3)−H bond arylation of aliphatic amides has been achieved via organophotoredox catalysis. The reaction could be realized at room temperature with visible light source and metal‐free catalyst. Quinuclidine is employed as an efficient HAT reagent and a range of aliphatic amides is employed as both substrate and solvent in the reaction. This photocatalyzed transformation provides a convenient protocol to afford a board range of N‐benzyl amides. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The azepine ring is a prominent structural scaffold in biologically significant molecules. In this study, we present a Ni(II)‐catalyzed asymmetric difunctionalization of alkynes, involving intermolecular regioselective arylation and intramolecular nitrile addition, enabling the synthesis of enantioenriched azepine derivatives. This reaction simultaneously installs an all‐carbon quaternary stereocenter and introduces an unprotected imine functionality, showing great promise for subsequent transformations. The reaction exhibits good tolerance toward various functional groups, resulting in high yields and enantioselectivities. The synthetic utility of this methodology is further demonstrated through gram‐scale synthesis and product derivatization. This research offers an efficient approach to the synthesis of seven‐membered nitrogen heterocycles. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Herein, we report nickel‐catalyzed cross‐coupling of gem‐difluorinated cyclopropanes with boronic acids, providing the corresponding arylated 2‐fluoroallylic scaffolds. This approach used commercially available phosphine ligand Xantphos to obtain monofluorinated alkenes with high regioselectivity and Z‐stereoselectivity. Mechanistic studies proposed a Ni(II)‐fluoroallyl pathway and excluded the radical pathway. Meanwhile, DFT study of the reductive elimination clarified the origin of the high linear selectivity. [ABSTRACT FROM AUTHOR]

We report the triply selective and sequential diversification of a single Csp3 carbon carrying Cl, Bpin and GeEt3 for the modular and programmable construction of sp3‐rich molecules. Various functionalizations of Csp3−Cl and Csp3−BPin (e.g. alkylation, arylation, homologation, amination, hydroxylation) were tolerated by the Csp3−GeEt3 group. Moreover, the methodological repertoire of alkyl germane functionalization was significantly expanded beyond the hitherto known Giese addition and arylation to alkynylation, alkenylation, cyanation, halogenation, azidation, C−S bond formation as well as the first demonstration of stereo‐selective functionalization of a Csp3‐[Ge] bond. [ABSTRACT FROM AUTHOR]

We report the synergistic combination of Pd(OAc)2 and Ag2O for the oxidative C−H arylation of (poly)fluoroarenes with aryl pinacol boronates (Ar‐Bpin) in DMF as the solvent. This procedure can be conducted easily in air, and without using additional ligands, to afford the fluorinated unsymmetrical biaryl products in up to 98 % yield. Experimental studies suggest that the formation of [PdL2(C6F5)2] in DMF as coordinating solvent does not take place under the reaction conditions as it is stable to reductive elimination and thus would deactivate the catalyst. Thus, the intermediate [Pd(DMF)2(ArF)(Ar)] must be formed selectively to give desired arylation products. DFT calculations predict a low barrier (5.87 kcal/mol) for the concerted metalation deprotonation (CMD) process between C6F5H and the Pd(II) species formed after transmetalation between the Pd(II)X2 complex and aryl‐Bpin which forms a Pd‐Arrich species. Thus a Pd(Arrich)(Arpoor) complex is generated selectively which undergoes reductive elimination to generate the unsymmetrical biaryl product. [ABSTRACT FROM AUTHOR]

The present work represents a novel methodology for the selective arylation of coumarin‐3‐carboxylates with arylboronic acids via a photochemical route, marking the first‐ever attempt for the direct alkenyl C−H arylation using rose bengal as a photocatalyst, which is a readily available and cost‐effective alternative to transition metal catalysis. The reaction proceeds smoothly in MeOH/H2O solvent media in the presence of radical initiator affording the arylated products in good yields (60–80 %). The reaction parameters such as visible light, radical initiator, oxidant, anhydrous solvent, and inert atmosphere play a crucial role for the success of this methodology. The substituents present on the substrate show a significant effect on the conversion. This study provides a valuable contribution to the field of organic synthesis offering a new and efficient approach to the arylation of coumarin‐3‐carboxylic acid esters with a broad substrate scope and high functional group tolerance. It is a versatile method and provides a direct access to biologically relevant 4‐arylcoumarin‐3‐carboxylates. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The azepine ring is a prominent structural scaffold in biologically significant molecules. In this study, we present a Ni(II)‐catalyzed asymmetric difunctionalization of alkynes, involving intermolecular regioselective arylation and intramolecular nitrile addition, enabling the synthesis of enantioenriched azepine derivatives. This reaction simultaneously installs an all‐carbon quaternary stereocenter and introduces an unprotected imine functionality, showing great promise for subsequent transformations. The reaction exhibits good tolerance toward various functional groups, resulting in high yields and enantioselectivities. The synthetic utility of this methodology is further demonstrated through gram‐scale synthesis and product derivatization. This research offers an efficient approach to the synthesis of seven‐membered nitrogen heterocycles. [ABSTRACT FROM AUTHOR]

This article explores the synthesis of N-arylated triazole derivatives using ligand-free copper catalysts. The authors optimize the reaction conditions and find that using CuCl as the catalyst, K3PO4 as the base, and DMF as the solvent yields the highest product yield. The study also investigates the substrate scope and finds that certain substitutions lead to higher yields. This research provides valuable insights into the synthesis of important compounds with potential pharmaceutical applications. The article acknowledges the support of the National Institute of Education, Singapore. [Extracted from the article]

Herein we report a method for the synthesis of thioethers by forging C(aryl)‐S bond via an aryne mechanism. The active aryne species can be generated from o‐diiodoarenes and NaH in THF at room temperature, then lead to the arylations of a wide range of aryl thiols and thioureas. Different from transition metal‐catalyzed cross‐coupling reactions, no disubstituted byproduct is formed in our protocol. The o‐iodoaryl thioether products are intermediates that could be transformed into pharmaceutically interesting molecules. [ABSTRACT FROM AUTHOR]

A light-induced method is developed for synthesizing azauracils. This method is independent from traditional methodology. Remarkably, this reaction can also be powered by sunlight. The applicability of this method is further demonstrated through its successful implementation in large-scale reactions and its use in synthesizing derivatives. [ABSTRACT FROM AUTHOR]

A four-step synthesis process of bifunctional, noncovalent organocatalysts based on the chiral (1R,2R)-cyclohexane-1,2-diamine scaffold containing a 1,2-benzenediamine H-bond donor was developed. Nucleophilic aromatic substitution of the 2-fluoronitrobenzene derivative with the commercial (1R,2R)-cyclohexane-1,2-diamine was followed by selective alkylation of the primary amino group, reduction of the aromatic nitro group and final derivatization of the primary aromatic amino group, i.e., acylation, sulfonation, reductive alkylation and arylation, leading to the four subtypes of organocatalysts. All new compounds were fully characterized. The prepared organocatalysts (32 examples) were tested in the Michael addition of acetylacetone to trans-β-nitrostyrene, yielding the addition product with incomplete conversions (up to 93%) and enantioselectivities of up to 41% ee. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of 1-substituted 5-aryl-1,2,4-triazoles by selective C—H arylation of 1-substituted 1,2,4-triazoles with non-activated aryl chlorides and aryl bromides under the catalysis by a palladium complex with a N-heterocyclic carbene ligand IPr*OMe using 1,1,2,2-tetraphenylethane-1,2-diol (TPEDO) as a catalyst activator is reported. [ABSTRACT FROM AUTHOR]

Carbo- and heterocycles are frequently used as crucial scaffolds in natural products, fine chemicals, and biologically and pharmaceutically active compounds. Transition-metal-catalyzed cyclization of 1,6-enynes has emerged as a powerful strategy for constructing functionalized carbo- and heterocycles. Despite significant progress, the regioselectivity of alkyne functionalization is entirely substrate-dependent. And only exo-cyclization/cross-coupling products can be obtained, while endo-selective cyclization/cross-coupling remains elusive and still poses a formidable challenge. In this study, we disclose a nickel-catalyzed switchable arylation/cyclization of 1,6-enynes in which the nature of the ligand dictates the regioselectivity of alkyne arylation, while the electrophilic trapping reagents determine the selectivity of the cyclization mode. Specifically, using a commercially available 1,10-phenanthroline as a ligand facilitates trans-arylation/cyclization to obtain seven-membered ring products, while a 2-naphthyl-substituted bisbox ligand promotes cis-arylation/cyclization to access six-membered ring products. Diastereoselective cyclizations have also been developed for the synthesis of enantioenriched piperidines and azepanes, which are core structural elements of pharmaceuticals and natural products possessing important biological activities. Furthermore, experimental and density functional theory studies reveal that the regioselectivity of the alkyne arylation process is entirely controlled by the steric hindrance of the ligand; the reaction mechanism involves exo-cyclization followed by Dowd-Beckwith-type ring expansion to form endo-cyclization products. Divergent functionalizations of pi bonds allow for synthetic chemists to move from simplicity to complexity. Here, the authors report a nickel-catalyzed switchable arylation/cyclization of 1,6-enynes in which the nature of the ligand dictates the regioselectivity of alkyne arylation, while the electrophilic trapping reagents determine the selectivity of the cyclization mode. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed asymmetric α-arylation of N-carbamoyl imine precursors containing CCl3, CF3 and CF2H is presented. This protocol provides facile access to a series of chiral α-aryl trichloroethylamines bearing various functional groups, with moderate to high yields (40–82% yield) and high enantioselectivity (80–99% ee). [ABSTRACT FROM AUTHOR]

Cu(II)-catalyzed N-arylation of electron-deficient NH-heterocycles 'in-water' at room temperature is described. A wide substrate scope with respect to structural and electronic variation of NH-heterocycles plus arylboronic acids allows product diversity. The functional group tolerance, 'gram-scale' synthesis, synthetic elaboration of N-arylated products and late-stage arylation are the distinct advantages. [ABSTRACT FROM AUTHOR]

Distyrylbenzenes (DSBs) are well‐known for their strong multicolour fluorescence. Fluorescence tuning of DSB via further functionalization/arylation, on the other hand, is uncommon. This paper reports a Pd‐catalysed direct arylation approach for introducing different aryl groups onto fluorobenzene‐containing DSB moiety (7) in high yields (67–72 %). The versatile methodology allows the substitution of neutral [tolyl (1)], electron‐deficient [p‐formyl benzene (2), p‐acetyl benzene (3), p‐nitrobenzene (4)] and electron‐rich [carbazole (5), triphenylamine (6)] aryl groups. The electron‐deficient aryls render mono‐substitution, while the electron‐rich counterparts promote di‐substitution. The compounds (1–6) show blue, green, and yellow fluorescence in both the solution and solid states; the fluorescence quantum yields reach >98 % and the peak maxima span from 425 to 560 nm. The mono‐carbazole DSB (5) exhibit white light emission (WLM) in polar solvents (acetone, DMF, CH3CN, DMSO and NMP) with very high fluorescence quantum yields (φf) of 60–80 %. For WLM, such high efficiency (φf) is somewhat uncommon. Moreover, visible‐to‐NIR reversible electrochromism is demonstrated by the TPA‐integrated DSB (6). The colour of 6 changes from pristine light yellow to orange, and the absorption maxima shifts from 372 to 1500 nm when a positive potential of 1.0 V vs Ag/Ag+ is applied. Moreover, the system shows high colouration efficiency in the NIR region with fast switching speeds for colouration and decolouration as fast as 0.98 s and 1.05 s. [ABSTRACT FROM AUTHOR]

We describe an efficient and versatile method for the direct C−H arylation of xanthines with aryl halides using Pd/P(o‐tolyl)3 as catalyst and Ag2O as an additive. Silver salts have been frequently used as an additive in the Pd‐catalyzed C−H bond activation reactions albeit in excessive amounts (2 to 4 eq.). Herein, we use of a stoichiometric amount (0.1 to 1 eq.) of Ag2O to obtain the optimum yields of C‐8 arylated products. This method exhibits broad substrate scope and enables synthesis of a wide range of xanthine derivatives by variation of aryl component at the C‐8 position. A key advantage of silver additive is that it reduces the catalyst loading and time required for the completion of reactions. Although kinetic experiments show that the inclusion of silver salt accelerates the rate of reaction, catalytic role of silver salt could not be conceived since the C−H bond cleavage is not a rate determining step. Silver salt presumably act as a terminal oxidant in the catalytic cycle and assist the regeneration of Pd catalyst. Moreover, preliminary assessment of biological activities of xanthines demonstrates that the C‐8 arylated xanthines derivatives efficiently inhibit the α‐Synuclein fibrillation, a key factor behind Parkinson's disease. [ABSTRACT FROM AUTHOR]

A low pKa (5.2), high polarizable volume (3.8 Å), and proneness to oxidation under ambient conditions make selenocysteine (Sec, U) a unique, natural reactive handle present in most organisms across all domains of life. Sec modification still has untapped potential for site‐selective protein modification and probing. Herein we demonstrate the use of a cyclometalated gold(III) compound, [Au(bnpy)Cl2], in the arylation of diselenides of biological significance, with a scope covering small molecule models, peptides, and proteins using a combination of multinuclear NMR (including 77Se NMR), and LC–MS. Diphenyl diselenide (Ph−Se)2 and selenocystine, (Sec)2, were used for reaction optimization. This approach allowed us to demonstrate that an excess of diselenide (Au/Se−Se) and an increasing water percentage in the reaction media enhance both the conversion and kinetics of the C−Se coupling reaction, a combination that makes the reaction biocompatible. The C−Se coupling reaction was also shown to happen for the diselenide analogue of the cyclic peptide vasopressin ((Se−Se)‐AVP), and the Bos taurus glutathione peroxidase (GPx1) enzyme in ammonium acetate (2 mM, pH=7.0). The reaction mechanism, studied by DFT revealed a redox‐based mechanism where the C−Se coupling is enabled by the reductive elimination of the cyclometalated Au(III) species into Au(I). [ABSTRACT FROM AUTHOR]

Development of new chiral ligands is essentially important in the field of asymmetric metal catalysis. Bispidines, steming from natural alkaloids, represent an intriguing yet underexplored class of chiral ligands. In this article, we developed a series of bispidine‐based chiral ligands with chirality locked in the side chain, and explore their properties by applying in the palladium‐catalyzed asymmetric addition of arylboric acids to cyclic N‐sulfonyl ketimines. A S,N‐bispidine ligand was found especially efficient, affording a series of chiral benzosultams with a quaternary chiral center in excellent yields with excellent ee values. Density functional theory (DFT) calculations and crystal structure of catalyst helped to propose a reasonable mechanism including a possible transition state model to explain the origin of stereoselectivity. [ABSTRACT FROM AUTHOR]

Di- and triarylmethanes are an important class of compounds in many fields. Here, we report an efficient light-induced arylation (alkylation) for the synthesis of diarylmethanes, bis(diarylmethyl)benzenes, arylalkylmethanes, and triarylmethanes from readily accessible N-sulfonylhydrazones and aryl/alkylboronic acids with the aid of Cs2CO3. In the presence of light, the synthesis of diarylmethanes was also achieved from aldehydes in a one-pot manner via a three-component approach in good yields. Furthermore, we have demonstrated the synthetic utility by synthesizing organoboron compounds and 2°-alcohol. [ABSTRACT FROM AUTHOR]

A Pd‐catalyzed heterocyclization/carbonylation/arylation cascade reaction between β,γ‐unsaturated N−Ts hydrazones and commercially available arylboronic acids as coupling partners is described, producing 2‐pyrazoline‐ketone derivatives in 11–78% yield. A detailed statistical analysis of reactivity patterns of boronic acids provided key information about the limitations of the method, highlighting the challenges of degradation pathways. Our methodology offers a tool for synthesizing diverse 2‐pyrazoline‐ketone derivatives, expanding the toolbox of accessible N−N‐heterocycles. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The rapid synthesis of structurally complicated electron donors & acceptors still remains a major challenge in organic solar cells (OSC). In this work, we developed a highly efficient strategy to access long‐chain oligomeric donor and acceptors for OSC applications. A series of cyclopentadithiophene (CPDT) and benzothiadiazole (BT)‐based π‐conjugated oligomers, i.e., three oligomeric acceptors (BTDT)n‐IC (n = 1—3) and one long‐chain oligomeric donor (BTDT)4‐RD, are facilely synthesized by an atom‐ and step‐economical, and labor‐saving direct C—H arylation (DACH) reaction (i.e., C—H/C—Br cross coupling). Note that (BTDT)4‐RD involving five CPDT, four BT and two rhodamine (RD) building blocks is the longest oligomeric donor in the fullerene‐free OSC devices ever reported. The dependence of the structure‐property‐performance correlation of (BTDT)n‐IC (n = 1—3) and (BTDT)4‐RD on the π‐conjugation lengths is thoroughly investigated by opto‐electrochemical measurements, bulk heterojunction (BHJ) OSC devices and microscopies. The (BTDT)1‐IC:PBDB‐T and (BTDT)4‐RD:Y6 BHJs achieve power conversion efficiencies of 9.14% and 4.51%, respectively. Our findings demonstrate that DACH reaction is a powerful tool to tune the opto‐electronic properties and device performances by regulating the lengths of π‐conjugated oligomers with varied numbers of repeating units. [ABSTRACT FROM AUTHOR]

Disubstituted isothiazolo[4,3-b]pyridines are known inhibitors of cyclin G-associated kinase. Since 3-substituted-7-aryl-isothiazolo[4,3-b]pyridines remain elusive, a strategy was established to prepare this chemotype, starting from 2,4-dichloro-3-nitropyridine. Selective C-4 arylation using ligand-free Suzuki-Miyaura coupling and palladium-catalyzed aminocarbonylation functioned as key steps in the synthesis. The 3-N-morpholinyl-7-(3,4-dimethoxyphenyl)-isothiazolo[4,3-b]pyridine was completely devoid of GAK affinity, in contrast to its 3,5- and 3,6-disubstituted congeners. Molecular modeling was applied to rationalize its inactivity as a GAK ligand. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of four new palladium complexes containing a benzimidazole core and examine their catalytic activities in the direct arylation of heteroaromatic species with aryl bromides. The complexes were characterized by 1H and 13C NMR spectroscopy, FT-IR spectroscopy, and elemental analysis. In the 13C NMR spectra, NCHN peaks of Pd(II) complexes were observed between 143.2 and 144.9 ppm. Also, the structure of 2b was determined by single-crystal XRD analysis. The obtained data suggest that the lengths of the Pd–N and Pd–Cl bonds are like those of previous Pd complexes. Direct arylation reactions, using KOAc as base and DMAc as solvent under inert conditions, were carried out with the synthesized complexes in the presence of various aryl bromides, and 2-acetylthiophene, 2-furaldehyde, and 1-methylpyrole-2-carboxaldehyde. Moderate to high yields were obtained under 1% mol catalyst loading conditions. The results showed that electron-donating and electron-withdrawing substituents on the aryl halides may produce coupling products in good yields in the presence of 2a–d. These findings contribute to the synthesis and design of palladium complexes containing benzimidazole cores. [ABSTRACT FROM AUTHOR]

A method of stereodivergent intramolecular ring‐opening arylation of amine‐tethered epoxides to 3,4‐disubstituted tetrahydroquinolines has been developed. The tuneable good stereoselectivity was attained by changing the catalyst from titanocene(III) catalyst to Lewis‐acidic zinc catalyst. [ABSTRACT FROM AUTHOR]

A novel strategy for the synthesis of 6‐methyl benzofuro[3,2‐c] quinoline derivatives via copper‐catalyzed dehydrogenative CO arylation has been presented. Optimization studies have been carried out by varying various catalysts, bases, solvents, and other physical parameters. Keeping use of this dehydrogenative cross‐coupling CO arylation reaction, a variety of bioactive building blocks like fused benzofuro quinoline heterocycles were smoothly assembled in moderate to higher yields. [ABSTRACT FROM AUTHOR]

Anions of carboxylic acids are widely used as the promoters of ruthenium-catalyzed reactions of C—H activation of substrates containing an N-donar directing group. The promoting effect of structure of anions of aliphatic and (hetero)aromatic carboxylic acids on the C—H arylation of benzene, furan, and thiophene rings in benzo[d]imidazol-2-yl-(hetero)arenes, wherein the benzimidazole moiety played the role of N-donor directing group, was evaluated. It was found that the structural effect of carboxylate anion on the efficiency of promotion of the catalytic system can significantly vary upon the arylation of different substrates. Adamantane-1-carboxylic acid was proposed as the most effective and universal promoter, based on which a new efficient catalytic system was developed for the selective arylation of benzo[d]imidazol-2-yl-(hetero)arenes. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The rapid synthesis of structurally complicated electron donors & acceptors still remains a major challenge in organic solar cells (OSC). In this work, we developed a highly efficient strategy to access long‐chain oligomeric donor and acceptors for OSC applications. A series of cyclopentadithiophene (CPDT) and benzothiadiazole (BT)‐based π‐conjugated oligomers, i.e., three oligomeric acceptors (BTDT)n‐IC (n = 1—3) and one long‐chain oligomeric donor (BTDT)4‐RD, are facilely synthesized by an atom‐ and step‐economical, and labor‐saving direct C—H arylation (DACH) reaction (i.e., C—H/C—Br cross coupling). Note that (BTDT)4‐RD involving five CPDT, four BT and two rhodamine (RD) building blocks is the longest oligomeric donor in the fullerene‐free OSC devices ever reported. The dependence of the structure‐property‐performance correlation of (BTDT)n‐IC (n = 1—3) and (BTDT)4‐RD on the π‐conjugation lengths is thoroughly investigated by opto‐electrochemical measurements, bulk heterojunction (BHJ) OSC devices and microscopies. The (BTDT)1‐IC:PBDB‐T and (BTDT)4‐RD:Y6 BHJs achieve power conversion efficiencies of 9.14% and 4.51%, respectively. Our findings demonstrate that DACH reaction is a powerful tool to tune the opto‐electronic properties and device performances by regulating the lengths of π‐conjugated oligomers with varied numbers of repeating units. [ABSTRACT FROM AUTHOR]