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Summary C–H phosphorylation was achieved by Earth-abundant nickel catalysts with waste-free electricity as the redox surrogate. The robust nickela-electrooxidative C–H activation of arenes, heteroarenes, and olefins with diverse phosphonating reagents successfully delivered arylphosphonates, phenylphosphine oxides, and diazaphospholidine oxides of relevance to bioactive compounds and materials. The guanidine-assisted electrooxidative C–P formation avoided chemical oxidants with molecular hydrogen as the sole byproduct. Catalytically relevant nickel(II) and nickel(III) intermediates were isolated and fully characterized by X-ray diffraction analysis. Catalytically relevant nickel complexes were observed by in operando high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) monitoring. Cyclic voltammetry analysis and density functional theory (DFT) calculations provided strong evidence for a nickel(III/IV/II) manifold.

C−H activation has emerged as one of the most efficient tools for the formation of carbon–carbon and carbon–heteroatom bonds, avoiding the use of prefunctionalized materials. In spite of tremendous progress in the field, stoichiometric quantities of toxic and/or costly chemical redox reagents, such as silver(I) or copper(II) salts, are largely required for oxidative C−H activations. Recently, electrosynthesis has experienced a remarkable renaissance that enables the use of storable, safe and waste‐free electric current as a redox equivalent. While major recent momentum was gained in electrocatalyzed C−H activations by 4d and 5d metals, user‐friendly and inexpensive nickela‐electrocatalysis has until recently proven elusive for oxidative C−H activations. Herein, the early developments of nickela‐electrocatalyzed reductive cross‐electrophile couplings as well as net‐redox‐neutral cross‐couplings are first introduced. The focus of this Minireview is, however, the recent emergence of nickel‐catalyzed electrooxidative C−H activations until April 2020., Go electro! Nickela‐electrocatalyzed C−H activations have emerged as a sustainable platform in molecular sciences that avoid substrate prefunctionalizations and chemical oxidants by electricity. The robust nickela‐electrooxidations enabled C−C, C−O, and C−N formations with ample scope under exceedingly mild conditions.

Catalytic materials design for upgrading CO2 into value-added fuels and chemicals at low temperature is attractive to reduce carbon pollution and dependence on fossil fuels. In the current issue of Nature Catalysis, Deng, Wang, and colleagues developed a vacancy-rich MoS2 catalyst for hydrogenation of CO2 into methanol with high catalytic activity, excellent selectivity, and industrial-relevant stability. Furthermore, an integration of in situ spectroscopic characterizations and theoretical calculations confirmed the key role of in-plane sulfur vacancies to this hydrogenation catalysis.

Nickel-catalyzed electrochemical C-H aminations were accomplished by chemo- and position-selective C-H activation with ample scope. Detailed mechanistic studies highlighted a facile C-H cleavage with unique chemo-selectivity, while cyclovoltammetric analysis provided support for a nickel(II/III/IV) manifold.

The performance of various transition-metal catalysts was explored in the step-economical synthesis of naturally occurring lamellarin alkaloids by C–H/N–H activation. The oxidative alkyne annulation proceeded efficiently by using sustainable ruthenium(II) catalysis, which set the stage for a concise synthesis of lamellarin D, lamellarin H and derivatives thereof.

Nickela‐electrooxidative C−H alkoxylations with challenging secondary alcohols were accomplished in a fully dehydrogenative fashion, thereby avoiding stoichiometric chemical oxidants, with H2 as the only stoichiometric byproduct. The nickela‐electrocatalyzed oxygenation proved viable with various (hetero)arenes, including naturally occurring secondary alcohols, without racemization. Detailed mechanistic investigation, including DFT calculations and cyclovoltammetric studies of a well‐defined C−H activated nickel(III) intermediate, suggest an oxidation‐induced reductive elimination at nickel(III)., II, III, or IV: Challenging secondary C−H alkoxygenations were accomplished with a versatile nickel electrocatalyst. Mechanistic investigation through isolation experiments, cyclovoltammetry, and density functional theory (DFT) calculations provided support for a process involving oxidation‐induced reductive elimination. MQ=6‐methylquinoline.

Ruthenium(II)-catalyzed meta-selective C-H (di)fluoromethylation was accomplished by phosphine and carboxylate cooperation. The remote C-H functionalization was characterized by ample substrate scope, thereby setting the stage for meta-(di)fluoromethylation through facile C-H cleavage.

A new method for palladium-catalyzed β-arylation of aliphatic and cycloaliphatic amides without conventional silver salts utilizing 2-aminopyridine-1-oxide moiety (PyO) as an N,O-bidentate group has been developed. Reactions proceeded smoothly in DMSO solvent in the presence of K2HPO4·3H2O, providing the β-arylated aliphatic amide products in a moderate-to-good yield. An important cyclopalladium intermediate, successfully obtained with a modest yield, could be converted to the monoarylation product and be used as catalyst in arylation reaction. Moreover, the PyO directing group was easily removed under base condition to generate aliphatic acids.

A highly efficient cobalt(II)-catalyzed alkynylation/annulation of terminal alkynes assisted by an N,O-bidentate directing group is described. This protocol is characterized by wide substrate scope utilizing cheap cobalt catalysts, and offers a new approach to 3-methyleneisoindolin-1-one, which can be converted into an oxadiazine salt in one step. Moreover, the directing group could be removed in three steps.

meta-Selective C-H alkylations of bioactive purine derivatives were accomplished by versatile ruthenium catalysis. Thus, the arene-ligand-free complex [Ru(OAc)2 (PPh3 )2 ] enabled remote C-H functionalizations with ample scope and excellent levels of chemo- and positional selectivities. Detailed experimental and computational mechanistic studies provided strong support for a facile C-H activation within a ruthenium(II/III) manifold.

Highly effective CuCl-mediated C-H alkoxylation of arenes and heteroarenes has been developed by using a 2-aminopyridine 1-oxide moiety as an N,O-bidentate directing group. The reaction proceeds smoothly using a broad range of substrates to afford o-alkoxylated benzoic and heteroaromatic amide products. Moreover, the reaction system shows remarkable compatibility when hexafluoroisopropanol is used as a coupling parter; halogen, nitro, ether, alkoxy, ester, and sulfonyl functional groups are all tolerated. The directing group can be easily removed by base hydrolysis, affording o-alkoxylated benzoic acids.

A new method of cobalt-catalyzed amination of arylamides with simple alkylamines is reported through C(sp2)–H bond functionalization. For the first time, inexpensive cobalt is exploited as the catalyst in the amination of C(sp2)–H bond using simple alkylamines.

A new method of cobalt-catalyzed amination of arylamides with simple alkylamines is reported through C(sp(2))-H bond functionalization. For the first time, inexpensive cobalt is exploited as the catalyst in the amination of C(sp(2))-H bond using simple alkylamines.

The cobalt(II)-oxalate-catalyzed reaction between arylacetylenes and N-protected arylamides with pyridin N-oxide as the directing group furnishes the title compounds in good to high yields and in a E/Z-selective manner (Z).

A highly efficient cobalt(II)-catalyzed alkynylation/annulation of terminal alkynes assisted by an N,O-bidentate directing group is described. This protocol is characterized by wide substrate scope utilizing cheap cobalt catalysts, and offers a new approach to 3-methyleneisoindolin-1-one, which can be converted into an oxadiazine salt in one step. Moreover, the directing group could be removed in three steps.

The reaction proceeds under mild conditions in the presence of Co(OAc)2·4H2O as the catalyst and tolerates a wide range of both alcohols and benzamide substrates, including even olefinic carboxamides.

Highly effective CuCl-mediated C—H alkoxylation of arenes and heteroarenes has been developed by using a 2-aminopyridine 1-oxide moiety as an N,O-bidentate directing group. The reaction proceeds smoothly using a broad range of substrates to afford o-alkoxylated benzoic and heteroaromatic amide products. Moreover, the reaction system shows remarkable compatibility when hexafluoroisopropanol is used as a coupling parter; halogen, nitro, ether, alkoxy, ester, and sulfonyl functional groups are all tolerated. The directing group can be easily removed by base hydrolysis, affording o-alkoxylated benzoic acids.

The cobalt-catalyzed alkoxylation of C(sp(2) )H bonds in aromatic and olefinic carboxamides has been developed. The reaction proceeded under mild conditions in the presence of Co(OAc)2 ⋅4H2 O as the catalyst and tolerates a wide range of both alcohols and benzamide substrates, including even olefinic carboxamides. In addition, this reaction is the first example of the direct alkoxylation of alkenes through CH bond activation.