Syntheses of substituted anilines primarily rely on palladium‐catalyzed coupling chemistry with prefunctionalized aryl electrophiles. While oxidative aminations have emerged as powerful alternatives, ...they largely produce undesired metal‐containing by‐products in stoichiometric quantities. In contrast, described herein is the unprecedented electrochemical C−H amination by cobalt‐catalyzed C−H activation. The environmentally benign electrocatalysis avoids stoichiometric metal oxidants, can be conducted under ambient air, and employs a biomass‐derived, renewable solvent for sustainable aminations in an atom‐ and step‐economical manner with H2 as the sole byproduct.
Zapping N: Electrochemical C−H aminations were realized in a biomass‐derived renewable solvent under mild reaction conditions. The method exploits electricity as a sustainable oxidant and H2 is the sole byproduct
Cobalt-catalyzed C–H activation by means of oxazolinyl assistance set the stage for versatile direct amidations with ample substrate scope. Thus, a high-valent cobalt(III) catalyst enabled C–H ...amidations with excellent levels of positional and chemo-selectivities. Mechanistic studies provided strong support for a kinetically relevant C–H functionalization.
Twofold CH functionalization of aromatic sulfonic acids was achieved with an in situ generated ruthenium(II) catalyst. The optimized cross‐dehydrogenative alkenylation protocol proved applicable to ...differently substituted arenes and a variety of alkenes, including vinyl arenes, sulfones, nitriles and ketones. The robustness of the ruthenium(II) catalyst was demonstrated by the chemoselective oxidative olefination of sulfonamides as well as sulfonyl chlorides. Mechanistic studies provided support for a reversible, acetate‐assisted CH ruthenation, along with a subsequent olefin insertion.
Versatile oxidative alkenylations of sulfonic acids, sulfonyl chlorides or sulfonamides were achieved by a robust ruthenium(II) catalyst with excellent substrate scope. Mechanistic studies suggested a reversible, acetate‐assisted CH ruthenation, along with a subsequent olefin insertion.
Electrochemical oxidative C−H/N−H activations with isocyanides have been realized with a versatile cobalt catalyst. The widely applicable cobalt catalysis manifold further enabled electrooxidative ...C−H/N−H carbonylations with carbon monoxide under ambient conditions. The C−H functionalizations were efficiently realized with ample scope and outstanding functional group tolerance in a user‐friendly undivided cell setup.
Two in one: Electrooxidative C−H activations are achieved by a versatile Co(OAc)2 catalyst with CO or isocyanides as C1 synthons and electricity as sustainable oxidant.
The hydroarylation of allenes via C–H activation was achieved with a versatile cationic cobalt(III) catalyst. Step- and atom-economical access to alkenylated heteroarenes is thus provided in a ...highly chemo- and regioselective manner. Detailed mechanistic studies were conducted, including kinetic studies and Hammett analysis, suggesting the catalytic cycle being initiated with a reversible N-ligand dissociation followed by a kinetically relevant arene C–H activation.
Herein, a three‐component cyclization reaction of benzimidazoles, aryl nitroalkenes and elemental sulfur has been developed. Cheap and easily available salicylic acid found to be an efficient ...mediator for the present transformation. This protocol provides a facile access to structurally significant imidazo2,1‐bthiazole skeleton from simple raw materials with a range of compatible synthetically useful functionalities. Furthermore, gram‐scale preparation of this method is effective, which enables potential applications of it in broader fields of molecule synthesis. Mechanistically, a reaction cascade involving sequential aza‐Michael addition, nucleophilic sulfuration, and deaminative aromatization was proposed.
A palladium‐catalyzed remote δ‐C−H selenylation of arylethylamide derivatives with readily available diselenides has been reported. This protocol relies on the use of a removable picolinamide ...directing group to access unsymmetrical diaryl selenides in 45–98% yields. Furthermore, the inactivated δ‐C(alkenyl)−H bond was also compatible in this reaction and afforded the thermo‐dynamically unfavorable Z‐selective‐alkenyl selenides with complete control of site‐ and stereoselectivity.
Cp*‐free cobalt‐catalyzed alkyne annulations by C−H/N−H functionalizations were accomplished with molecular O2 as the sole oxidant. The user‐friendly oxidase strategy proved viable with various ...internal and terminal alkynes through kinetically relevant C−H cobaltation, providing among others step‐economical access to the anticancer topoisomerase‐I inhibitor 21,22‐dimethoxyrosettacin. DFT calculations suggest that electronic effects control the regioselectivity of the alkyne insertion step.
Mit O2: Co(OAc)2 enabled the aerobic C−H/N−H functionalization with O2 as the sole oxidant under Cp*‐free conditions, which enabled step‐economical access to anticancer isoquinolones by highly selective C−H activation (see scheme, Cp*=pentamethylcyclopentadienyl).
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