Despite the wide use of aryl radicals in organic synthesis, current methods to prepare them from aryl halides, carboxylic acids, boronic acids, and diazonium salts suffer from limitations. Aryl triflates, easily obtained from phenols, are promising aryl radical progenitors but remain elusive in this regard. Inspired by the single electron transfer process for aryl halides to access aryl radicals, we developed a simple and efficient protocol to convert aryl triflates to aryl radicals. Our success lies in exploiting sodium iodide as the soft electron donor assisted by light. This strategy enables the scalable synthesis of two types of important organic molecules, i.e., aryl boronates and aryl iodides, in good to high yields, with broad functional group compatibility in a transition-metal-free manner at room temperature. This protocol is anticipated to find potential applications in other aryl-radical-involved reactions by using aryl triflates as aryl radical precursors.

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Aryl carboxylic acids are stable and readily available in great structural diversity both from natural and well-established synthetic procedures, which make them promising starting materials in organic synthesis. The conversion of benzoic acids into high-value molecules is of great importance and have gained much interest of synthetic chemists. The recent development of single-electron (1e À ) activation strategy has been esteemed as a complementary method for the transformation of benzoic acids. In this context, carboxylate groups can be selectively transferred into reactive aryl carboxylic radical, aryl radical, and acyl radical by electrocatalysis, photocatalysis, or in the presence of some SET oxidants. Based on these radical species, remarkable advancements have been achieved for the rapid formation of various chemical bonds over the past 10 years. In this review, we summarize recent advances in single electron activation of aryl carboxylic acids, with an emphasis on reaction scope, catalytic system, limitation, and underlying reaction mechanism.

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An efficient copper‐catalyzed method for the synthesis of 2‐haloimidazopyridines with aminopyridines and haloalkynes using molecular oxygen as oxidant in a one‐pot manner has been developed. In this process, the reaction appears to be very general and suitable for the construction of a variety of 2‐halo‐substituted imidazopyridines, imidazopyrazines and imidazopyrimidines. The intermolecular oxidative diamination of haloalkynes was achieved for the first time. Importantly, the mild reaction conditions and the efficient conversion of the alkyl‐substituted haloalkynes are great improvements over the existing methods. Moreover, the resultant 2‐haloimidazo[1,2‐a]pyridines could be efficiently converted to other functionalized imidazopyridine products via substitution, coupling reactions and other transformations, which further indicates potential applications of this method in synthetic and pharmaceutical chemistry.magnified image

Cobalt-catalyzed stereodivergent semi-hydrogenation of internal alkynes to alkenes is developed.

Organic azides are highly reactive, which have long established as versatile building blocks in the assembly of structurally diverse N‐containing heterocycles. The conversion of organic azides into high‐value compounds is of great importance and a subject of enormous current interest. Transition metal‐catalyzed C(sp2)−H amination/annulation of organic azides provides a powerful tool for the transformation of organic azides into a wide range of biologically important heterocyclic frameworks. In this review, we aim to summarize the recent progress on organic azides‐mediated C(sp2)−H amination/annulation for N‐heterocycle synthesis enabled by transition metal catalysts. Representative strategies are discussed in detail, including catalytic systems, reaction scopes, limitations and mechanisms.

This review article provides an overview of the recent progress in the transformations of anthranils, which have emerged as versatile building blocks in the assembly of various C–N bonds and medicinally active heterocyclic systems.