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Herein disclosed is the first example of diarylation/annulation of benzoic acids via an iridium catalyst system. This protocol provides a step‐economic and highly efficient pathway to 1‐aryl, 1,3‐diaryl, 1,7‐diaryl and 1,3,7‐triaryl spirobifluorenes from readily available starting materials. The applications of multi‐aryl spirobifluorenes as pure hydrocarbon (PHC) hosts for red, green, and blue (RGB) phosphorescent organic light‐emitting diodes (PhOLEDs) were explored. Due to high triplet energies, 1,3‐diaryl spirobifluorenes exhibit the potential as the host material of blue PhOLEDs. 1,7‐Diaryl spirobifluorene can serve as the host of green PhOLEDs. 1,3,7‐Triaryl spirobifluorene is a high‐performance host for red PhOLEDs, which exhibits a high external quantum efficiency (EQE) up to 27.3 %. This work not only exemplifies the great potential of multi‐aryl spirobifluorenes as PHC hosts, but also offers a new approach for the synthesis of these PHC hosts. [ABSTRACT FROM AUTHOR]

The pursuit of efficient synthetic route to thienoacenes represents an appealing yet challenging task in the fields of both organic synthetic chemistry and organic functional materials. In this work, we disclose a rhodium‐catalyzed cascade C−H annulation of phenacyl phosphoniums with (benzo)thiophenes via a Heck‐type pathway to provide a new class of planar thienoacenes, which involves the formation of three Caryl‐Caryl bonds and one Caryl−O bond in a single operation. The neutral S,O‐heteroacenes exhibit superior stability and adopt a herringbone‐like packing mode with efficient π–π stacking in the crystals, suggesting their potential in organic semiconducting materials. This work first exemplifies the superiority of cascade oxidative C−H annulation involving a Heck‐type pathway in the development of concise access to heteroacenes. [ABSTRACT FROM AUTHOR]

Described herein is a strategy to construct cationic azahelicenes through the three‐component annulation reaction of isoquinoline, indole, and 1,2‐dichloroethane (DCE), in which DCE serves as an in situ activating agent for C1−H activation of isoquinoline, a vinyl equivalent, and a solvent. This in situ activation annulation reaction features a facile one‐step synthesis and complete regioselectivity. The complete regioselectivity of C1 over C3 for the isoquinoline ring paves a path to the helical structure in a highly ordered sequence. One of the synthesized ionic [5]azahelicenium fluorophores exhibits the potential to serve as a mitochondria‐targeted biomarker with good photostability and low cytotoxicity. [ABSTRACT FROM AUTHOR]

Disclosed herein is a counterion additive-switched rhodium-catalyzed cascade triple C–H annulation of 4-hydroxy-1-naphthaldehydes with alkynes, in which six chemical bonds are formed in one-pot. This reaction enables the rapid assembly of diverse polycyclic pyrylium and pyridinium fluorophores, which leads to two specific mitochondria-labeling reagents with low cytotoxicity and superior photostability. [ABSTRACT FROM AUTHOR]

Reported herein is a cascade Lewis acid-promoted intramolecular Friedel–Crafts-type imidoylation and Rh(iii)-catalyzed C–H activation/annulation of benzimidoyl chlorides and alkynes, providing a general and concise one-pot approach to 7H-dibenzo[de,h]quinoline analogues. This divergent approach is based on a convergent retrosynthetic disconnection strategy. [ABSTRACT FROM AUTHOR]

Described herein is the merging of allylic C(sp3)–H activation and directed C(sp2)–H activation into a single approach for discovering unprecedented chemical transformations. As a proof-of-concept, we disclose for the first time the rhodium-catalyzed regioselective oxidative annulation of anilines with allylbenzenes to deliver a variety of indoles. In this work, the C3 and C2 positions of the allylic segment are set to construct C–N and C–C bonds, respectively. [ABSTRACT FROM AUTHOR]

Disclosed herein is the merging of C−H activation and radical chemistry, enabling rapid access to a structurally diverse family of fused carbohelicenes through the fusion of α‐acetylnaphthalenes with alkynes under oxidative conditions. This cascade process exhibits exquisite chemoselectivity and regioselectivity. The reaction pathway was analyzed by intermediate separations, control experiments, radical trapping, EPR, MALDI‐TOF‐MS, and ESI‐HRMS experiments, and shown to involve a C2−H activation/radical reaction/C8−H activation relay. Carbohelicenes were synthesized with unparalleled ease in a C−H activation/radical reaction/C−H activation sequence starting from α‐acetylnaphthalenes and alkynes. This process exemplifies the high compatibility of ionic and radical transformations. [ABSTRACT FROM AUTHOR]

Abstract: The functionalization of thiophenes is a fundamental and important reaction. Herein, we disclose iridium‐catalyzed one‐pot annulation reactions of (benzo)thiophenes with (hetero)aromatic or α,β‐unsaturated carboxylic acids, which afford thiophene‐fused coumarin‐type frameworks. Dearomatization reactions of 2‐substituted thiophenes with α,β‐unsaturated carboxylic acids deliver various thiophene‐containing spirocyclic products. The occurrence of two interconnected reactions provides direct evidence for a Heck‐type pathway. The mechanistic scenario described herein is distinctly different from the SEAr and concerted metalation–protodemetalation (CMD) pathways encountered in the well‐described oxidative C−H/C−H cross‐coupling reactions of thiophenes with other heteroarenes. [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]

In this work, we report novel Rh(iii)-catalyzed chemoselective functionalizations of tertiary aniline N-oxides with alkynes, including annulation via the sequential C(sp2)–H and C(sp3)–N activation for the formation of N-alkylindoles and an O-atom transfer (OAT) process for the synthesis of acetophenones. [ABSTRACT FROM AUTHOR]

The purpose of this article is to give a brief review of weak chelation-assistance as a powerful means for the rhodium-catalyzed annulation of arenes with alkynes. The use of commonly occurring functional groups (e.g., ketones, aldehydes, carboxylic acids and alcohols) as the directing groups enriches the versatility of auxiliary ligands and extends the scope of products. This short article offers an overview on emerging procedures, highlights their advantages and limitations, and covers the latest progress in the rapid synthesis of organic functional materials and natural products. [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]

A novel ruthenium complex HSRC is prepared and successfully applied for the synthesis of spiro carbocyclic indenes via a [3 + 2] annulation strategy. [ABSTRACT FROM AUTHOR]

A diagram is presented which explains the rhodium-catalyzed annulation of N-Methoxybenzamides consisting ynesulfonamides at room temperature.