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Reported herein is a rhodium(III)‐catalyzed three‐component annulation reaction of simple pyridines, alkynes, and 1,2‐dichloroethane (DCE), affording a streamlined pathway to diverse ring‐fused pyridiniums. DCE not only serves as a vinyl equivalent but also as an in situ activating agent for pyridine C2−H activation. A cationic five‐membered rhodacycle complex has been isolated and proposed as a possible intermediate. This strategy can be extended to other N‐containing heteroarenes for the synthesis of multiring‐fused pyridiniums. These multicomponent reactions exhibit excellent regioselectivity for 1,3‐diynes, paving a path to the cascade cyclization of 3‐fluoropyridine or N‐methylpyridin‐3‐amine with 1,3‐diynes for the construction of brand‐new tricyclic‐fused pyrano‐ or hydropyridoquinolizinium salts. These ionic fluorophores have been investigated as potential biomarkers. Triple agent: Disclosed herein is a rhodium(III)‐catalyzed multicomponent reaction of simple pyridines, alkynes, and 1,2‐dichloroethane (DCE) to afford a streamlined pathway to diverse ring‐fused pyridiniums. DCE serves as a vinyl equivalent and an in situ activating agent for pyridine C2−H activation, as well as a solvent. [ABSTRACT FROM AUTHOR]

Described herein is the synthesis of stable oxonium-doped polycyclic aromatic hydrocarbons (PAHs) by the rhodium-catalyzed C−H activation/annulations of naphthalene-type aldehydes with internal alkynes. This protocol provides four divergent reaction types, including two unexpected annulations with an oxygen transposition process, which lead to diverse types of phenalenyl-fused pyrylium cations comprising a four-, five-, or six-ring-fused π-conjugated core. The annulations exhibit an exquisite regioselectivity and a high tolerance of sensitive functional groups. These PAHs feature intriguing photophysical properties such as full-color tunable fluorescence emission, high quantum yield, and positively charged core, and can be reduced easily to the phenalenyl radicals. [ABSTRACT FROM AUTHOR]

An unprecedented Rh-catalyzed ketone-directed vinylic C−H activation/[4+2] O-annulation of α-aryl enones with internal alkynes followed by a Cu-catalyzed ring contraction in air to provide multiaryl-substituted furan derivatives has been developed. The preliminary mechanism study identifies the active pyrylium salt as the key intermediate. [ABSTRACT FROM AUTHOR]

The first example of cobalt-catalyzed oxidative C−H/C−H cross-coupling between two heteroarenes is reported, which exhibits a broad substrate scope and a high tolerance level for sensitive functional groups. When the amount of Co(OAc)2⋅4 H2O is reduced from 6.0 to 0.5 mol %, an excellent yield is still obtained at an elevated temperature with a prolonged reaction time. The method can be extended to the reaction between an arene and a heteroarene. It is worth noting that the Ag2CO3 oxidant is renewable. Preliminary mechanistic studies by radical trapping experiments, hydrogen/deuterium exchange experiments, kinetic isotope effect, electron paramagnetic resonance (EPR), and high resolution mass spectrometry (HRMS) suggest that a single electron transfer (SET) pathway is operative, which is distinctly different from the dual C−H bond activation pathway that the well-described oxidative C−H/C−H cross-coupling reactions between two heteroarenes typically undergo. [ABSTRACT FROM AUTHOR]

A rapid access to 2,2′-bithiazole-based copolymers has been developed on the basis of the sequential palladium-catalyzed CH/CX and CH/CH coupling reactions. To assemble a 'copolymer' through homopolymerization, a type of symmetric A-B-A-type building block is designed as the monomer and prepared via the regioselective C5H arylation of thiazole. A PdCl2/CuCl-cocatalyzed oxidative CH/CH homopolymerization has been established to afford the 2,2′-bithiazole-based copolymers with high Mn (up to 69400). The current protocol features atom- and step-economy and exhibits a potential in the highly efficient construction of conjugated copolymers. [ABSTRACT FROM AUTHOR]

Pd-Catalysed ortho-selective oxidative C–H/C–H cross-coupling of aromatic carboxylic acids with arenes and subsequent intramolecular Friedel–Crafts acylation has been accomplished for the first time through a chelation-assisted C–H activation strategy. Starting from the readily available substrates, a variety of fluorenone derivatives are obtained in one pot. The direct use of naturally occurring carboxylic acid functionalities as directing groups avoids unnecessary steps for installation and removal of an extra directing group. [ABSTRACT FROM AUTHOR]

Reported herein is the first example of a transition-metal- catalyzed internal oxidative C-H/C-H cross-coupling between two (hetero)arenes through a traceless oxidation directing strategy. Without the requirement of an external metal oxidant, a wide range of phenols, including phenol-containing natural products, can undergo the coupling with azoles to assemble a large library of highly functionalized 2-(2-hydroxyphenyl)azoles. The route provides an opportunity to rapidly screen white-light-emitting materials. As illustrative examples, two bis(triphenylamine)-bearing 2-(2-hydroxyphenyl) oxazoles, which are difficult to access otherwise, exhibit bright white-light emission, high quantum yield, and thermal stability. Also presented is the first example of the white-light emission, in a single excited-state intramolecular proton transfer system, of 2-(2-hydroxyphenyl)azoles, thus highlighting the charm of C-H activation in the discovery of new organic optoelectronic materials. [ABSTRACT FROM AUTHOR]

Disclosed herein is a RhIII-catalyzed chelation-assisted activation of unreactive C [ABSTRACT FROM AUTHOR]

Disclosed herein is a RhIII-catalyzed chelation-assisted activation of unreactive C [ABSTRACT FROM AUTHOR]

RhIII-catalyzed oxidative CH/CH cross-coupling between (hetero)aromatic carboxylic acids and various heteroarenes has been accomplished to construct highly functionalized ortho-carboxy-substituted bi(hetero)aryls. The use of a carboxy group as the directing group obviates tedious steps for installation and removal of extra directing groups, and enables a facile one-step synthesis of ortho-carboxy bi(hetero)aryls. The method provides opportunities for rapid assembly of a library of important fluorene and coumarin-type poly-heterocycles through intramolecular electrophilic substitution or oxidative lactonization. As illustrative examples, the strategy developed herein greatly streamlines accesses to a variety of appealing polyheterocycles such as DTPO (5 H-dithieno[3,2- b:2′,3′- d]pyran-5-one), CPDTO (cyclopentadithiophen-4-one), and indenothiophenes. [ABSTRACT FROM AUTHOR]

A rhodium(iii)-catalyzed dehydrogenative cross-coupling reaction has been developed for the synthesis of bi(hetero)aryl structures by using oxime ethers as the directing group. This protocol features a relatively broad substrate scope and a good tolerance of functional groups. [ABSTRACT FROM AUTHOR]

Fully loaded: A coordinating activation strategy has been developed to furnish α‐quaternary α‐amino acids through the iron(III)‐catalyzed oxidative functionalization of α‐C(sp3)H bonds of α‐tertiary α‐amino acid esters. The reaction exhibits a broad substrate scope for both α‐amino acids and nucleophiles (Nu) as well as good functional‐group tolerance (see scheme, DTBP=di‐tert‐butyl peroxide, DCE=1,2‐dichloroethane). [ABSTRACT FROM AUTHOR]

Doppelrolle: In einer neuartigen, RhIII ‐ katalysierten Synthese ortho ‐ alkenylierter tertiärer Aniline fungiert eine spurlose dirigierende Gruppe zugleich als internes Oxidans (siehe Schema). Ein fünfgliedriger cyclometallierter RhIII ‐ Komplex wird als plausible Zwischenstufe vorgeschlagen und konnte durch Röntgenstrukturanalyse charakterisiert werden. [ABSTRACT FROM AUTHOR]

CC bond construction: A palladium‐catalyzed oxidative C sp 3H/C sp 3H cross‐coupling is shown to forge CC bonds rather than C sp 3C sp 3 bonds through reactions of indolin‐2‐ones or benzofuran‐2‐ones with O‐benzoyl hydroxylamines in the absence of an added oxidant. [ABSTRACT FROM AUTHOR]

In this work, we have disclosed the nickel-catalyzed unactivated β-C(sp3)–H bond arylation of aliphatic acid derivatives with aryl iodides/bromides via bidentate chelation-assistance of an 8-aminoquinoline moiety. These preliminary results indicate the intrinsic catalytic potential of nickel metal for unactivated C(sp3)–H bond arylation. [ABSTRACT FROM AUTHOR]

Transition metal-mediated C-H bond activation and functionalization represent one of the most straightforward and powerful tools in modern organic synthetic chemistry. Bi(hetero)aryls are privileged π-conjugated structural cores in biologically active molecules, organic functional materials, ligands, and organic synthetic intermediates. The oxidative C-H/C-H coupling reactions between two (hetero)arenes through 2-fold C-H activation offer a valuable opportunity for rapid assembly of diverse bi(hetero)aryls and further exploitation of their applications in pharmaceutical and material sciences. This review provides a comprehensive overview of the fundamentals and applications of transition metal-mediated/catalyzed oxidative C-H/C-H coupling reactions between two (hetero)arenes. The substrate scope, limitation, reaction mechanism, regioselectivity, and chemoselectivity, as well as related control strategies of these reactions are discussed. Additionally, the applications of these established methods in the synthesis of natural products and exploitation of new organic functional materials are exemplified. In the last section, a short introduction on oxidant- or Lewis acid-mediated oxidative Ar-H/Ar-H coupling reactions is presented, considering that it is a very powerful method for the construction of biaryl units and polycylic arenes. [ABSTRACT FROM AUTHOR]

The copper-mediated tandem oxidativeC(sp2)–H/C(sp)–Hcross-coupling and intramolecular annulation of arenes with terminalalkynes has been developed, which offers a highly efficient approachto the 3-methyleneisoindolin-1-one scaffold. In this oxidative couplingprocess, Cu(OAc)2acts as both the promoter and the terminaloxidant. This protocol features a wide substrate scope; high functionalgroup tolerance; exclusive chemo-, regio-, and stereoselectivity;and simple, easily available, and inexpensive reaction system. Thetransformation has demonstrated for the first time that Cu(OAc)2can be renewable after undergoing an oxidative reaction. [ABSTRACT FROM AUTHOR]

Anefficient protocol for the synthesis of (hetero)aryl carboxylic estershas been achieved by Pd-catalyzed C–H carbonylation of (hetero)areneswith aryl formates. A relatively wide range of functional groups canbe tolerated in this transformation, and the corresponding estersare obtained in good yields. On this basis, an intramolecular oxidativeC–H/C–H coupling has been developed to prepare indolo[3,2-c]coumarins. [ABSTRACT FROM AUTHOR]

The synthesized 12-azapyrene salts show an intense fluorescence in both solution and solid state what facilitates an optoelectronic application. [ABSTRACT FROM AUTHOR]

The Pd-catalyzed direct C-H cyclization of dibromoarylpyrroles with various diarylalkynes produces the title ullazines in good yields. [ABSTRACT FROM AUTHOR]

An abstract of the article "Rhodium(III)-Catalyzed Activation of C(sp3)--H Bonds and Subsequent Intermolecular Amidation at Room Temperature," by Xiaolei Huang and colleagues is presented.

The transformation of N-aryl indolyl aldehydes with symmetric 1,2-diaryl or 1,2-dialkylalkynes proceeds regioselectively and tolerates multiple functional groups including chloro, cyano, and methoxy carbonyl groups. [ABSTRACT FROM AUTHOR]

The β-C(sp3)-H bonds of aliphatic amides containing a quinolinyl group [e.g. (I)] are activated by nickel through a chelation. [ABSTRACT FROM AUTHOR]