Transition metal-catalyzed isocyanide insertion has served as a fundamental and important chemical transformation. Classical isocyanide insertion usually occurs between organohalides and nucleophiles, which normally involves tedious and non-atom-economical prefunctionalization processes. However, oxidative C−H/N−H isocyanide insertion offers an efficient and green alternative. Herein, a nickel-catayzed oxidative C−H/N−H isocyanide insertion of aminoquinoline benzamides has been developed. Different kinds of iminoisoindolinone derivatives could be synthesized in good yields by utilizing Ni(acac)₂ as the catalyst. In this transformation, isocyanide serves as an efficient C1 connector, which further inserted into two simple nucleophiles (C−H/N−H), representing an effective way to construct heterocycles.

A transformation is presented that enables chemists to construct 4-aryl tetralones via visible-light-induced cyclodimerization–oxygenation of styrene under very mild conditions. Adding a catalytic amount of CuOAc obviously improves the yield. A mechanistic study reveals that the photoredox catalyst played the role of activating O₂ while Cu affected the reactivity of reactive oxygen species (ROS).

An oxidative β-Csp³−H functionalization of tert-butanol (tBuOH) for the construction of C−S bonds through an iodine-catalyzed Csp³−H/S−H coupling was successfully achieved. Different kinds of mercaptans were shown to be good coupling partners, affording the desired products in good yields. This protocol not only offers a novel method for the synthesis of β-hydroxy thioethers, but also provides an effective strategy for selective radical/radical cross-coupling.

Controlling selectivity is of central importance to radical chemistry. However, the highly reactive and unstable radical intermediates make this task especially challenging. Herein, a strategy for taming radical redox reactions has been developed, in which solvent-bonding can alter the reactivity of the generated radical intermediates and thereby drastically alter the reaction selectivity at room temperature. Various β-oxy sulfoxides and β-hydroxy sulfides can be facilely obtained, some of which are difficult to synthesize by existing methods. Notably, neither a metal catalyst nor any further additives are necessary in these processes.

Controlling selectivity is of central importance to radical chemistry. However, the highly reactive and unstable radical intermediates make this task especially challenging. Herein, a strategy for taming radical redox reactions has been developed, in which solvent-bonding can alter the reactivity of the generated radical intermediates and thereby drastically alter the reaction selectivity at room temperature. Various β-oxy sulfoxides and β-hydroxy sulfides can be facilely obtained, some of which are difficult to synthesize by existing methods. Notably, neither a metal catalyst nor any further additives are necessary in these processes.

The efficient selective oxidation and functionalization of CH bonds with molecular oxygen and a copper catalyst to prepare the corresponding ketones was achieved with ethyl chloroacetate as a promoter. In this transformation, various substituted N-heterocyclic compounds were well tolerated. Preliminary mechanistic investigations indicated that organic radical species were involved in the overall process. The N-heterocyclic compounds and ethyl chloroacetate work synergistically to activate CH bonds in the methylene group, which results in the easy generation of free radical intermediates, thus leading to the corresponding ketones in good yields.

A novel palladium-catalyzed CH double carbonylation introduces two adjacent carbonyl groups for the synthesis of isatins from readily available anilines. The reaction proceeds under atmospheric pressure of CO with high regioselectivity and without any additives. Density functional theory investigations indicate that the palladium-catalyzed double carbonylation catalytic cycle is plausible.

The selective radical/radical cross-coupling of two different organic radicals is a great challenge due to the inherent activity of radicals. In this paper, a copper-catalyzed radical/radical CH/PH cross-coupling has been developed. It provides a radical/radical cross-coupling in a selective manner. This work offers a simple way toward β-ketophosphonates by oxidative coupling of aryl ketone o-acetyloximes with phosphine oxides using CuCl as catalyst and PCy₃ as ligand in dioxane under N₂ atmosphere at 130 °C for 5 h, and yields ranging from 47 % to 86 %. The preliminary mechanistic studies by electron paramagnetic resonance (EPR) showed that, 1) the reduction of ketone o-acetyloximes generates iminium radicals, which could isomerize to α-sp³-carbon radical species; 2) phosphorus radicals were generated from the oxidation of phosphine oxides. Various aryl ketone o-acetyloximes and phosphine oxides were suitable for this transformation.

Because of the lack of redox ability, zinc has seldom been used as a catalyst in dehydrogenative cross-coupling reactions. Herein, a novel zinc-catalyzed dehydrogenative C(sp²)H/C(sp)H cross-coupling of terminal alkynes with aldehydes was developed, and provides a simple way to access ynones from readily available materials under mild reaction conditions. Good reaction selectivity can be achieved with a 1:1 ratio of terminal alkyne and aldehyde. Various terminal alkynes and aldehydes are suitable in this transformation.

A novel palladium-catalyzed CH double carbonylation introduces two adjacent carbonyl groups for the synthesis of isatins from readily available anilines. The reaction proceeds under atmospheric pressure of CO with high regioselectivity and without any additives. Density functional theory investigations indicate that the palladium-catalyzed double carbonylation catalytic cycle is plausible.

The selective radical/radical cross-coupling of two different organic radicals is a great challenge due to the inherent activity of radicals. In this paper, a copper-catalyzed radical/radical CH/PH cross-coupling has been developed. It provides a radical/radical cross-coupling in a selective manner. This work offers a simple way toward β-ketophosphonates by oxidative coupling of aryl ketone o-acetyloximes with phosphine oxides using CuCl as catalyst and PCy₃ as ligand in dioxane under N₂ atmosphere at 130 °C for 5 h, and yields ranging from 47 % to 86 %. The preliminary mechanistic studies by electron paramagnetic resonance (EPR) showed that, 1) the reduction of ketone o-acetyloximes generates iminium radicals, which could isomerize to α-sp³-carbon radical species; 2) phosphorus radicals were generated from the oxidation of phosphine oxides. Various aryl ketone o-acetyloximes and phosphine oxides were suitable for this transformation.

Because of the lack of redox ability, zinc has seldom been used as a catalyst in dehydrogenative cross-coupling reactions. Herein, a novel zinc-catalyzed dehydrogenative C(sp²)H/C(sp)H cross-coupling of terminal alkynes with aldehydes was developed, and provides a simple way to access ynones from readily available materials under mild reaction conditions. Good reaction selectivity can be achieved with a 1:1 ratio of terminal alkyne and aldehyde. Various terminal alkynes and aldehydes are suitable in this transformation.

The Cu^I/Cu^II and Cu^I/Cu^III catalytic cycles have been subject to intense debate in the field of copper-catalyzed oxidative coupling reactions. A mechanistic study on the Cu^I/Cu^II redox process, by X-ray absorption (XAS) and electron paramagnetic resonance (EPR) spectroscopies, has elucidated the reduction mechanism of Cu^II to Cu^I by 1,3-diketone and detailed investigation revealed that the halide ion is important for the reduction process. The oxidative nature of the thereby-formed Cu^I has also been studied by XAS and EPR spectroscopy. This mechanistic information is applicable to the copper-catalyzed oxidative cyclization of β-ketocarbonyl derivatives to dihydrofurans. This protocol provides an ideal route to highly substituted dihydrofuran rings from easily available 1,3-dicarbonyls and olefins.

A copper-catalyzed ketooxygenation of electron-deficient alkenes was developed. This approach combines OH alkylation, aerobic decarboxylation, and oxygenation in one transformation. Mechanistic investigation of this reaction showed that the copper salt is responsible for both generating the amidoxyl radical and promoting aerobic decarboxylation.

Among various kinds of radical reactions, the addition of carbon-centered radicals to unsaturated bonds represents a powerful tool for the construction of different C−C and C−X (X=N, O, S, etc.) bonds, in which typically applied unsaturated bonds include alkenes, alkynes, imines, carbonyls, and even thiocarbonyls. When C=X bonds are utilized as the radical acceptors, reactions usually occur at the carbon position to generate a heteroatom radical, during which C−C coupling products are formed. This reaction mode has dominated this field for several decades. However, there is also another unconventional type of radical addition mode, in which carbon-centered radicals attack the heteroatom position of C=X bonds to generate carbon radicals, during which selective C−X bond formation is achieved. This reaction mode demonstrates an effective method for the construction of different C−X bonds, such as C−O, C−N, and C−S bonds. This Focus Review gives an overview of recent advances in this unconventional field.

In recent decades, iodine-catalyzed oxidative coupling reactions utilizing CH and XH as nucleophiles have received considerable attention because they represent more efficient, greener, more atom-economical, and milder bond-formation strategies over transition-metal-catalyzed oxidative coupling reactions. This Focus Review gives a brief summary of recent development on iodine-catalyzed oxidative coupling reactions utilizing CH and XH as nucleophiles.

A copper-catalyzed radical oxidative trifluoromethylation and arylation of electron-withdrawing alkenes has been developed, in which economical sodium trifluoromethanesulfinate is used as the CF₃ source. A preliminary kinetic investigation indicated that the generation of CF₃ radicals under the mild conditions might be a facile process.

Among various types of radical reactions, the addition of carbon radicals to unsaturated bonds is a powerful tool for constructing new chemical bonds, in which the typical applied unsaturated substrates include alkenes, alkynes and imines. Carbonyl is perhaps the most common unsaturated group in nature. This work demonstrates a novel CO bond formation through carbon-centered radical addition to the carbonyl oxygen of amide or ester, in which amide and ester groups are easily activated through the radical process. EPR spectroscopy and radical clock experiments support the radical process for this transformation, and density functional theory (DFT) calculations support the possibility of carbon-centered radical addition to the carbonyl oxygen of amides or esters.

A reagent-free oxidative cyclization between α-picoline derivatives and nitroolefins has been developed. This approach, in which the nitro group acts as an internal oxidant, provides an extremely simple, efficient, and atom-economic way to construct heteroaromatic indolizine derivatives.

β-Lactam scaffolds are considered to be ideal building blocks for the synthesis of nitrogen-containing compounds. A new palladium-catalyzed oxidative carbonylation of N-allylamines for the synthesis of α-methylene-β-lactams is reported. DFT calculations suggest that the formation of β-lactams via a four-membered-ring transition state is favorable.

Photochemistry has ushered in a new era in the development of chemistry, and photoredox catalysis has become a hot topic, especially over the last five years, with the combination of visible-light photoredox catalysis and radical reactions. A novel, simple, and efficient radical oxidative decarboxylative coupling with the assistant of the photocatalyst [Ru(phen)₃]Cl₂ is described. Various functional groups are well-tolerated in this reaction and thus provides a new approach to developing advanced methods for aerobic oxidative decarboxylation. The preliminary mechanistic studies revealed that: 1) an SET process between [Ru(phen)₃]²⁺* and aniline play an important role; 2) O₂ activation might be the rate-determining step; and 3) the decarboxylation step is an irreversible and fast process.

A palladium-catalyzed oxidative carbonylative esterification of a variety of functionalized alcohols under base- and ligand-free conditions has been demonstrated. A CO/olefin combination was utilized as the acylating reagent with O₂ as a benign oxidant. Notably, the scope of the substrate alcohols has been greatly broadened.

Photochemistry has ushered in a new era in the development of chemistry, and photoredox catalysis has become a hot topic, especially over the last five years, with the combination of visible-light photoredox catalysis and radical reactions. A novel, simple, and efficient radical oxidative decarboxylative coupling with the assistant of the photocatalyst [Ru(phen)₃]Cl₂ is described. Various functional groups are well-tolerated in this reaction and thus provides a new approach to developing advanced methods for aerobic oxidative decarboxylation. The preliminary mechanistic studies revealed that: 1) an SET process between [Ru(phen)₃]²⁺* and aniline play an important role; 2) O₂ activation might be the rate-determining step; and 3) the decarboxylation step is an irreversible and fast process.

A palladium-catalyzed oxidative carbonylative esterification of a variety of functionalized alcohols under base- and ligand-free conditions has been demonstrated. A CO/olefin combination was utilized as the acylating reagent with O₂ as a benign oxidant. Notably, the scope of the substrate alcohols has been greatly broadened.

Through the use of [Ru(bpy)₃Cl₂] (bpy=2,2′-bipyridine) and [Ir(ppy)₃] (ppy=phenylpyridine) as photocatalysts, we have achieved the first example of visible-light photocatalytic radical alkenylation of various α-carbonyl alkyl bromides and benzyl bromides to furnish α-vinyl carbonyls and allylbenzene derivatives, prominent structural elements of many bioactive molecules. Specifically, this transformation is regiospecific and can tolerate primary, secondary, and even tertiary alkyl halides that bear β-hydrides, which can be challenging with traditional palladium-catalyzed approaches. The key initiation step of this transformation is visible-light-induced single-electron reduction of CBr bonds to generate alkyl radical species promoted by photocatalysts. The following carboncarbon bond-forming step involves a radical addition step rather than a metal-mediated process, thereby avoiding the undesired β-hydride elimination side reaction. Moreover, we propose that the Ru and Ir photocatalysts play a dual role in the catalytic system: they absorb energy from the visible light to facilitate the reaction process and act as a medium of electron transfer to activate the alkyl halides more effectively. Overall, this photoredox catalysis method opens new synthetic opportunities for the efficient alkenylation of alkyl halides that contain β-hydrides under mild conditions.

Using moelcular oxygen as the terminal oxidant, various aryl halide-containing β-aryl ketones and aldehydes can be synthesized directly from readily available allyic alcohols and boronic acids via palladium-catalyzed oxidative cross-coupling reactions. The dual roles of copper, including electron-carrier and Lewis acid functions, are supposed to be critical for the high reactivity and selectivity of this aerobic oxidative coupling transformation.

Oxidative Carbonylierungen haben in den letzten Jahren ein breites Interesse geweckt, und insbesondere die Synthese von Carbonat- und Harnstoffderivaten durch oxidative Carbonylierung von Alkoholen und Aminen wurde intensiv untersucht. Eine neuartige Entwicklung ist die direkte Verwendung von Organometallverbindungen (RM) und Kohlenwasserstoffen (RH) als Nucleophile zum Aufbau einer C-C-Bindung in oxidativen Carbonylierungen. Dieser Kurzaufsatz stellt diese neue Art der oxidativen Carbonylierung vor.

Oxidative carbonylation reactions have attracted broad interest from both academia and industry in recent years. Enormous efforts have gone into the syntheses of carbonate and urea derivatives through the oxidative carbonylation of alcohols and amines. Very recently, organometallic reagents (RM) and hydrocarbons(RH) were directly employed as nucleophiles to construct a CC bond in oxidative carbonylation reactions. This Minireview summarizes this novel type of oxidative carbonylation reaction.

Pincer thioamide Pd^II complex 2 was prepared, and its reaction with cyclohexylzinc chloride yielded novel pincer thioimide Pd^II complex 3 besides Pd⁰ species. The structures of complexes 2 and 3 were confirmed by X-ray analysis. Both complexes are efficient catalysts for Negishi couplings involving primary and secondary alkyl zinc reagents bearing β-hydrogen atoms. At a concentration of 0.1–0.5 mol % both catalysts readily promoted reactions at room temperature or even at 0 °C. The operational simplicity of these processes, in conjunction with the easy accessibility of both catalysts and substrates, promises synthetic utility of this new methodology. An experiment on a scale of 19.35 g carried out at very low catalyst loading of 2 (turnover number: 6 100 000) highlighted the potential application of the catalytic system. Monoalkyl and dialkyl zinc reagents displayed different reactivities and selectivities in reactions with aryl iodides catalyzed by complexes 2 or 3, and isomerization in reactions involving acyclic secondary alkyl zinc derivatives was suppressed by using appropriate amounts of dialkyl zinc reagents. Based on preliminary kinetic profiles and reaction evidence, three possible pathways are proposed for the reactions involving acyclic secondary alkyl zinc reagents to rationalize the difference between mono-alkyl and dialkyl zinc derivatives.

An electron-deficient diene, L₁, was found to be an effective ligand in facilitating palladium-catalyzed Negishi couplings involving primary and secondary alkylzinc reagents. The reactions took place readily at 60 °C in THF with 5 mol% of a catalyst generated in situ from bis(acetonitrile)palladium dichloride [PdCl₂(MeCN)₂] and L₁, and functional groups such as chloro, bromo, etc. attached to phenyl ring as well as β-H atoms adjacent to the reaction site were well tolerated. The problematic isomerizations in secondary alkyzinc reagents involved in the reactions reported in the literature were also observed in our system when isopropylzinc chloride was employed alone as the nucleophile. However, the isomerization was significantly suppressed when i-Pr₂Zn was utilized in the presence of L₁.