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An efficient heterogeneous Pd/Cu synergistic catalysis system without a ligand was utilized for C–H arylation of azoles. The reaction exhibits excellent catalytic activity with high functional group tolerance. The synergistic effect between the Cu2O core and PdCu shell was confirmed, whereas pure PdCu nanocages and Cu2O exhibited negligible catalytic activity. [ABSTRACT FROM AUTHOR]

Herein we developed a palladium-catalyzed coupling of 2,3-enopyranose with arylboronic acid using a removable oxyacetamide directing group, which provides an efficient method for the synthesis of C-2 aryl sugars. The synthesized products were subsequently utilized as glycosyl donors in O/S glycosylation, enabling regio- and stereoselective production of 1,2-disubstituted branched sugars. [ABSTRACT FROM AUTHOR]

We report a dual transition metal electrocatalytic approach for C(sp3)–C(sp3) bond cleavage and arylation of cyclic alcohols, providing an efficient and sustainable method for site-specific arylation of ketones. The reaction involves electrophotochemical cerium-catalysed generation of alkoxyl radicals from readily accessible alcohols. Subsequently, homolytic cleavage of the β-C–C bond leads to the generation of carbon-centered radicals that could be effectively utilized by nickel catalysis powered by cathode reduction to deliver the remote arylated ketone products. [ABSTRACT FROM AUTHOR]

A novel class of chain-like multidentate oxalamide ligands with additional coordinating groups was developed for the coupling of (hetero)aryl bromides with both alcohols and phenols under mild conditions. Introduction of oxygen atoms in N-alkyl chains is pivotal for the high catalytic efficiency and broad substrate versatility. [ABSTRACT FROM AUTHOR]

We demonstrate (1) detectable halogen bonding is not critical for enabling light-driven radical generation from diaryliodonium salts and (2) radicals generated by this route can be captured by transition-metals for C–H arylation reactions. These results are the first step toward developing new metal-catalyzed aryl radical couplings without exogenous photocatalysts. [ABSTRACT FROM AUTHOR]

Treatment of 2-methylsulfinylbenzazoles with triflic anhydride in the presence of phenols yields the corresponding 4-(p-hydroxyphenyl)-2-methylsulfanylbenzazoles. This regioselective dehydrative C–H/C–H coupling arylation represents a rare example of functionalizations on the benzene rings of benzo-fused azoles. [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]

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]

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 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]

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]

This work discloses an iridium-catalyzed selective arylation of B(6)–H of 3-Ar-o-carboranes with arylboronic acid via direct B–H activation for the first time. A series of unsymmetric and symmetric 3,6-diaryl-o-carboranes decorated with diverse active groups have been synthesized with moderate to excellent yields under mild conditions. This work offers an efficient approach for selective arylation of B(6)–H with arylboronic acid and has important value for selective functionalization of o-carboranes. [ABSTRACT FROM AUTHOR]

We herein report regio- and enantioselective arylation of β,γ-alkynyl-α-imino esters with pyrroloisoquinolines. Using chiral phosphoric acid catalysts, a wide range of novel axially chiral tetrasubstituted α-amino allenoates were accessed in good yields with excellent enantioselectivities. Notably, this transformation occurred preferentially at the sterically more hindered C1-position of pyrroloisoquinolines. The potential scalability and late-stage functionalization demonstrated the utility of the current protocol. [ABSTRACT FROM AUTHOR]

Photochemical reductive deamination of alpha-amino aryl alkyl ketones under photosensitizer-free conditions is presented. This protocol features high efficiency and selectivity. A plausible reaction pathway is proposed based on ultraviolet–visible absorption investigation, control experiments and deuterium-labelling studies. Mechanistic study reveals that the alpha-hydrogen atom of the ketone product originated from water. [ABSTRACT FROM AUTHOR]

The first dual nickel/photoredox-catalyzed enantioselective reductive cross-coupling of racemic α-chloro thioesters with aryl iodides has been developed. This strategy avoids the need for organometallic reagents or stoichiometric metal reductants. This reaction could tolerate a wide range of substrate scope with excellent reactivity and high enantioselectivities (up to 91% ee) to access a variety of chiral α-aryl thioesters. The synthetic utility of the corresponding α-aryl thioesters is demonstrated. Furthermore, we explored the mechanism of such an enantioselective radical cross-coupling process. [ABSTRACT FROM AUTHOR]

N-nitro type reagents have been demonstrated as mild nitration tools in recent years. This work presents an exploration of direct nitration of aryl alkenes mediated by DNDMH, a novel N-nitro type reagent developed in our previous study. It exhibits herein a new property of DNDMH as an effective direct nitration reagent for aryl alkenes, through probably the delivery of nitro radicals with the aid of TEMPO and Cu(OAc)2. [ABSTRACT FROM AUTHOR]

We have developed an effective photochemical method for site-selective (hetero)arylation of polychlorinated heteroarenes. This approach eliminates the need for transition metal catalysts and photosensitizers by relying on in situ formation of unconventional electron donor–acceptor (EDA) complexes between two substrates and a basic additive. Our protocol yields chlorine-containing biaryl heterocyclic compounds with high levels of site-selectivity, which are of significant importance in both synthetic and medicinal chemistry. [ABSTRACT FROM AUTHOR]

We report herein the palladium-catalysed mono-selective C–H arylation of [2.2]paracyclophane (PCP) with diverse aryl iodides in the absence of any pendant directing groups, providing straightforward and modular access to C4-arylated [2.2]paracyclophanes. Moreover, a new PCP-containing biaryl monophosphine complex could be readily obtained through further derivation of the arylated product. [ABSTRACT FROM AUTHOR]

Herein, we report the rhodium-catalyzed domino arylation/cyclization reaction of unactivated internal alkynes to afford the optically active indenols in excellent yields (up to 92%) and extremely high enantioselectivities (up to 99% ee) in the presence of new amide substituted chiral diene ligands. Notably, a total of 21 new chiral diene ligands are synthesized, which are potential choices for other asymmetric reactions. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed synthesis of benzosilacyclobutenes has been developed via position-selective C(sp3)–H bond activation, including those having substituents at the methylene carbon on the 4-membered silacycle. The obtained products could be engaged in the palladium- or nickel-catalyzed ring-expansion reactions to give compounds possessing 6-membered silacycles. [ABSTRACT FROM AUTHOR]

By combining the Lewis acid Zn(C6F5)2 with nucleophilic diarylzinc (ZnAr2) reagents, we report the atom-efficient arylation of N-tosylimines under mild conditions. Mechanistic studies through the isolation of key intermediates reveal how the two zinc species act cooperatively to activate the imine substrate and regenerate the ZnAr2 reagent, enabling a limiting 50 mol% to be employed. [ABSTRACT FROM AUTHOR]

Herein, we report the first microwave-assisted remote-C – H functionalization aided by a simple nitrile directing template. Notably, the present protocol showed a broad substrate scope VIA enabling meta-C – H arylation, acetoxylation, and cyanation. Significantly, the microwave-accelerated meta-C – H functionalization was effective with short reaction times without compromising yields and site selectivity. In addition, ibuprofen drug diversification was accomplished by carrying out arylation, acetoxylation, and cyanation. Importantly, meta-dual-hetero functionalization has been presented. [ABSTRACT FROM AUTHOR]

The construction of diaryl alkanes from aromatic aldehydes or ketones with electron-deficient arenes is achieved in the presence of trivalent phosphine under electrochemical conditions. Reductive coupling between electron-deficient arenes and the carbonyl groups of aldehydes or ketones occurs at the cathode to yield diaryl alcohols. At the anode, the trivalent phosphine reagent may undergo single-electron oxidation to generate its radical cation, which reacts with the diaryl alcohols to form dehydroxylated products. [ABSTRACT FROM AUTHOR]

Benzylic amine derivatives are ubiquitous structural motifs in organic chemistry. Herein we report a direct synthesis of these compounds via a direct desulfonylative C-arylation of O-tosyl hydroxamates. The applicability of this Ru-catalyzed aminoalkylation is being exemplified by a set of late-stage functionalizations of natural products. [ABSTRACT FROM AUTHOR]

A family of planar chiral indene-fused ferrocenes were prepared through an intramolecular asymmetric C–H arylation in excellent yields (up to 99%) with excellent enantioselectivities (up to 99% ee). They were thereafter successfully transformed to chiral ferrocenyl phosphines, featuring both planar and central chiralities, in good yields (up to 83%) and excellent diastereoselectivities (up to 99% de) through highly diastereoselective phosphination. This protocol offers a general method for planar and central chiral ferrocenyl phosphines. The potential applications of the newly developed ligands were demonstrated by a Pd-catalyzed enantioselective allylic alkylation reaction, in which high enantioselectivity (92% ee) and good yield (89%) were obtained. [ABSTRACT FROM AUTHOR]

The first example of Pd(II)-catalyzed anomeric arylation of 3-aminosugars is reported by using an L,X-type transient directing group (TDG) approach combined with an external 2-pyridone ligand. The released free amine was in situ transformed into an azide function, which was then exploited in a CuAAC to increase the molecular complexity and prepare a variety of complex substituted C3-triazolo C-glycosides in good yields. [ABSTRACT FROM AUTHOR]

Chemical labeling of proteins in live cells helps to probe their native functions in biological systems. Aryl azides are chemically inert under physiological conditions, but they are activated by certain external stimuli. Recently, photocatalytic live-cell applications of aryl azides by visible light irradiation have become a burgeoning new field in chemical biology. In this Feature Article, we focus on the recent progress of protein labeling in live cells with aryl azides induced by visible-light irradiation. Light irradiation activates aryl azides to generate highly reactive intermediates, which enables protein labeling for protein functionalization, crosslinking, and profiling. The activation mechanism of aryl azides by light irradiation is categorized as photolysis, energy-transfer, and electron-transfer. The extracellular and intracellular protein labeling applications in live cells with aryl azides induced by visible light are discussed, including recent advances in red-light-induced extracellular protein labeling. [ABSTRACT FROM AUTHOR]

Regioselective, five-fold B–H activation of the monocarborane cluster [CB11H12]− at the positions B7–11 has been accomplished. Selective substitution of these positions by B–H activation has not been reported before. Our protocol involves directing group assistance by the carboxylic acid functionality and is based on palladium catalysis using iodoarene coupling partners. Penta-arylated products are obtained in a single step with yields ranging from 42% to 89% and with good functional group tolerance. X-Ray crystal structures for five new compounds confirm the selective substitution of the lower belt of the monocarborane cage. [ABSTRACT FROM AUTHOR]

Azobenzene-based unnatural amino acid motifs were synthesized via Pd(II)-catalyzed diastereoselective C(sp3)–H arylation of amino acid carboxamides with iodoacetanilides and Mills azo coupling. [ABSTRACT FROM AUTHOR]

An interesting substrate-controlled reactivity switch has been observed in the reaction of α-fluoro-β-ketoamides with arynes. The reaction of secondary α-fluoro-β-ketoamides with arynes provided access to α-aryl-α-fluoroacetamides through an arylation/deacylation sequence. Interestingly, the reaction of tertiary α-fluoro-β-ketoamides resulted in the C–C σ-bond insertion reaction to afford 1,2-disubstituted arenes. [ABSTRACT FROM AUTHOR]

A novel, Pd-catalyzed oxidative Heck reaction of non-activated alkenes synergistically directed by bifunctional groups has been developed firstly by using O2 as a green oxidant, yielding the oxidative Heck products with excellent yields in a regio- and stereoselective manner. This bifunctional synergistic activation mechanism was demonstrated by experimental analysis and detailed computational studies, wherein the hydroxyl group directs the migratory insertion of the alkenes and the trifluoromethyl group facilitates the subsequent β-H elimination and reductive elimination. Moreover, a pesticidal active compound was synthesized using the bifunctional synergistically directed C–H arylation as the key step, which demonstrated its synthetic utility. [ABSTRACT FROM AUTHOR]

2-Styrylthiophene-based donor–acceptor linear conjugated polymers with tunable cyano substituents are atom-economically obtained via direct C–H arylation for platinum-free photocatalytic hydrogen production, affording a HER of up to 9.79 mmol h−1 g−1. [ABSTRACT FROM AUTHOR]

Here we report CdS quantum dot (QD) gels as highly efficient and unique photocatalysts for organic synthesis. We found that the photocatalytic activity of CdS QD gel was superior to phosphine oxide- and thiolate-capped CdS QDs for dehalogenation and α-amine arylation reactions because of the high accessibility of its surface sites to the substrates. In addition, we discovered the unique reactivity of CdS QD gel for ring-opening during α-amine arylation of tetrahydroisoquinoline via the reductive cleavage of C–N bonds. QD gels provide new opportunities in photocatalysis due to their unique surface interactions with the substrates or intermediates. [ABSTRACT FROM AUTHOR]

Bis(trialkylsilyl) monochalcogenides and diorganyl dichalcogenides, (R3Si)2E and R2E2 (E = S, Se or Te and R = alkyl, aryl or allyl group), have emerged in the past decade as excellent reagents for the synthesis of metal chalcogenide nanoparticles (NPs) and clusters owing to their ability to transfer the chalcogenide anion (E2−) under ultra-mild conditions and versatility in reacting even with non-conventional metal reagents or being employed in a variety of synthetic methods. In comparison, the related non-silylated diorganyl monochalcogenides R2E have received attention only recently for the solution phase synthesis of metal chalcogenide NPs. In spite of sharing many similarities, these three families of organyl chalcogenides are different in their coordination ability and decomposition behavior, and therefore in reactivities towards metal reagents. This feature article provides a concise overview on the use of these three families as synthons for the ultralow-temperature synthesis of metal chalcogenide nanomaterials, deliberating their different decomposition mechanisms and critically assessing their advantages for certain applications. More specifically, it discusses their usefulness in (i) affording molecular precursors with different kinetic and thermal stabilities, (ii) isolating reactive intermediates for comprehending the mechanism of molecule-to-nanoparticle transformation and, therefore, achieving fine control over the synthesis, (iii) stabilizing isolable metastable or difficult-to-achieve phases, and (iv) yielding complex ternary nanoparticles with controlled stoichiometry or composites with sensitive materials without modifying the characteristics of the latter. Besides providing a perspective on the low-temperature synthesis of nanomaterials, this overview is expected to assist further progress, particularly in the field of R2E, leading to interesting materials including metastable ones for new applications. [ABSTRACT FROM AUTHOR]

We report on two different sets of air-stable derivatives of pentafluoroorthotellurate containing fluorinated and non-fluorinated aryl groups. The acid cis-PhTeF4OH was obtained in gram scale and further transformed to Ag[cis-PhTeF4O], which was used as a cis-PhTeF4O transfer reagent to obtain [PPh4][cis-PhTeF4O]. Furthermore, the synthesis of trans-(C6F5)2TeF3OH was achieved by a selective hydrolysis of trans-(C6F5)2TeF4 in the presence of KF and subsequent protonation by aHF. Quantum-chemical calculations show a higher acidity and robustness against fluoride abstraction for trans-(C6F5)2TeF3OH compared to cis-PhTeF4OH. [ABSTRACT FROM AUTHOR]

A Pd-catalyzed, native α-amino acid derivative-directed benzylic C–H bond arylation/oxidation with aryl iodides was developed. The natural amino acid auxiliary could serve as a desired building block for formation of 5-aryl-1,4-benzodiazepin-2-ones after removal of the trifluoroacetyl protecting group. The bifunctional reaction probably proceeded through a sequential benzylic arylation/oxidation process. [ABSTRACT FROM AUTHOR]

A new organocatalytic asymmetric method for the synthesis of enantioenriched triarylmethanes is developed. Different from the conventional approaches featuring asymmetric arylation, the present study employs asymmetric reduction via C–H bond formation as the key step. This approach does not require the presence of a heteroaryl ring or the presynthesis of unstable para-quinone methides. Instead, the stable racemic triarylmethanols were used as substrates for the in situ generation of the intermediates with a suitable chiral phosphoric acid catalyst. [ABSTRACT FROM AUTHOR]

Herein, N-heterocyclic carbene-directed Ir(III)-catalyzed cascade C–H arylation/annulation of N-arylimidazolium with diaryliodonium salts has been accomplished for the first time via a quadruple C–H activation strategy to construct imidazo[1,2-f]phenanthridinium structures. This protocol overcomes the compatibility of three kinds of different C–H activations with high catalytic efficiency, which allows ortho-unhindered N-arylimidazoliums to undergo a diarylation/annulation reaction, affording a variety of polysubstituted imidazo[1,2-f]phenanthridiniums. Neutral imidazo[1,2-f]phenanthridines are also prepared via a demethylation reaction of imidazo[1,2-f]phenanthridiniums. [ABSTRACT FROM AUTHOR]

We describe here a facile synthesis of 9-arylfluorenes and spirobifluorenes from readily available 1,1-diarylmethylamines and iodoarenes through Pd-cataylsed C(sp2)–H arylation and a sequential deaminative annulation. The reaction features high efficiency and simplicity of operation, constituting an interesting shortcut to access fluorene compounds. [ABSTRACT FROM AUTHOR]

With the idea of exploiting metal templated C–S bond forming reactions to achieve modification of cysteines in bacterial proteins, a cyclometalated Au(III) compound was explored in a competitive chemoproteomic approach in S. aureus cell extracts. More than 100 ligandable cysteines were identified, of which more than 50% were not engaged by organic α-chloroacetamides in a previous study, indicating that organometallic compounds expand the ligandable space in bacteria. A selected interaction was validated using an enzyme activity assay, and intact protein mass spectrometry showed cysteine arylation of an unprecedented target. The obtained results demonstrate that this family of organogold compounds has potential for therapeutic protein targeting via selective, covalent modification of cysteine residues in bacteria. [ABSTRACT FROM AUTHOR]

Direct arylation cross-coupling reaction was employed to prepare quinone-based conjugated polymer cathodes, which realize a high reversible capacity of 200 mA h g-1 at 0.05 A g-1, an excellent rate capability of 111 mA h g-1 at 30 A g-1 (150C), and a stable cycling performance for more than 3000 cycles. [ABSTRACT FROM AUTHOR]

N-Heterobiaryls are common skeletons found in biological molecules, pharmaceuticals and ligands. Herein, we document an efficient and redox-neutral photocatalytic system to obtain functionalized N-heterobiaryls under mild conditions. Substrates bearing variegated functional groups are compatible with the developed photocatalytic conditions. This method is translatable to gram-scale synthesis, with a photocatalyst loading as low as 0.1 mol% and minimal variation of the yield. The starting materials are commercially available, demonstrating the practicality and accessibility of this methodology. Interestingly, phenols can serve both as coupling partners and proton donors. Arenes without a phenolic hydroxyl group also underwent efficient coupling with HFIP as a solvent. [ABSTRACT FROM AUTHOR]

We have developed a catalyst-free visible-light-driven C(sp2)–H arylation of unprotected phenols with arylbromides to give 2-arylated phenols. This reaction proceeds through the excitation of an electron donor–acceptor complex between a phenolate and an arylbromide, electron transfer, and debrominative C(sp2)–C(sp2) coupling. [ABSTRACT FROM AUTHOR]

The addition of nucleophilic organometallic species onto in situ generated azabicyclobutanes enables the selective formation of 3-arylated azetidine intermediates through strain-release. Single pot strategies were further developed for the N-arylation of resulting azetidines, employing either SNAr reactions or Buchwald–Hartwig couplings. [ABSTRACT FROM AUTHOR]

Chlorobenzenes are important starting materials for the preparation of commercially valuable triarylphosphines and tetraarylphosphonium salts, but their use for the direct arylation of elemental phosphorus has been elusive. Here we describe a simple photochemical route toward such products. UV-LED irradiation (365 nm) of chlorobenzenes, white phosphorus (P4) and the organic superphotoreductant tetrakis(dimethylamino)ethylene (TDAE) affords the desired arylphosphorus compounds in a single reaction step. [ABSTRACT FROM AUTHOR]

A versatile synthetic protocol involving the room temperature direct arylation of benzothiazole with a wide variety of iodoarenes under Ag-promoted Pd-catalyzed conditions in HFIP as the reaction solvent has been presented. A sequential HFIP-promoted selective iodination of arenes followed by Pd-catalyzed direct arylation of benzothiazole has also been disclosed. The utility of the developed protocol has been demonstrated by the synthesis of anti-tumor agents, PMX-610 and CJM-126 (precursor). [ABSTRACT FROM AUTHOR]

A series of cationic π-extended imidazolium salts were synthesized by a sequential Cu-catalyzed arylation/annulation and photocyclization strategy in a simple but efficient way. Among them, a nine-fused-ring compound with a doubly aza[5]helical geometry is by far the largest cationic polycyclic heteroaromatic with a central imidazolium core. [ABSTRACT FROM AUTHOR]

A mechanistic study is performed on the reaction method for iron-catalyzed C–H methylation with AlMe3 reagent, previously proposed to involve cyclometalated iron(III) intermediates and an iron(III)/(I) reaction cycle. Detailed spectroscopic studies (57Fe Mössbauer, EPR) during catalysis and in stoichiometric reactions identify iron(II) complexes, including cyclometalated iron(II) intermediates, as the major iron species formed in situ under catalytic reaction conditions. Reaction studies identify a cyclometalated iron(II)-methyl species as the key intermediate leading to C–H methylated product upon reaction with oxidant, consistent with a previously proposed iron(II)/iron(III)/iron(I) reaction manifold for C–H arylation. [ABSTRACT FROM AUTHOR]

A method is presented for the synthesis of diaryl cyclic vinylogous esters. The sequence of C(sp3)–H arylation events is programed under the differentiated reactivity of the aryl halides, and the optimized reaction system is effectively diverted from producing dihomo-arylated products. The site selectivity of the second arylation is notably modulated by the substitution pattern of the substrates. [ABSTRACT FROM AUTHOR]

exo-Metallacycles have become the key reaction intermediates in activating various remote C(sp2)–H and C(sp3)–H bonds in the past decade and aided in achieving unusual site-selectivity. Various novel exo-chelating auxiliaries have assisted metals to reach desired remote C–H bonds of different alcohol and amine-derived substrates. As a result, a wide range of organic transformations of C–H bonds like halogenation, acetoxylation, amidation, sulfonylation, olefination, acylation, arylation, etc. were accessible using the exo-metallacycle strategy. In this review, we have summarized the developments in C–H bond activation via four-, five-, six-, seven- and eight-membered exo-metallacycles and the key reaction intermediates, including the mechanistic aspects, are discussed concisely. [ABSTRACT FROM AUTHOR]