We report a conceptually distinct strategy for the synthesis of 1,1-diarylalkanes and triarylalkanes. Key to this approach is the use of light to simultaneously trigger (i) formation of a Co III −H species which undergoes H atom transfer (MHAT) to styrenes, giving a carbon-centered radical, and (ii) generation of a persistent (hetero)arene radical. Selective coupling of these two species yields Markovnikov hydroarylation products under mild conditions and without precious metals. In contrast to many previous approaches, electron-deficient (hetero)arene coupling partners are favored and it is possible to construct highly congested quaternary centers, including those with three different aryl groups.

Catalytic hydrogen atom transfer from metal‐hydrides to alkenes allows feedstock olefins to be used as alkyl radical precursors. The chemoselectivity of this process makes it an attractive synthetic tool and as such it has been regularly used in synthesis of complex molecules. However, onwards reactivity is limited by compatibility with the conditions which form the key metal‐hydride species. Now, through the merger with photocatalysis or electrochemistry, milder methods are emerging which can unlock entirely new reactivity and offer perspectives on expanding these methods in unprecedented directions. This review outlines the most recent developments in electro‐ and photochemical cobalt catalysed methods and offers suggestions on the future outlook.

We report a dual-catalytic platform for the crossdehydrogenative-coupling between (benzo-)thiazoles and amines which combines low loadings of an iridium photoredox catalyst and a cobaloxime catalyst under blue light irradiation. This transformation occurs without stoichiometric oxidants, giving products in moderate to excellent yields. DFT calculations support the key role of Co(II) for rearomatization of the radical-addition intermediate to generate the product.

Katalytische Wasserstoffatomübertragung von Metallhydriden an Alkene ermöglicht es Olefine als Ausgangsmaterial für Alkylradikale zu verwenden. Aufgrund der Chemoselektivität dieses Prozesses, ist es ein attraktives Werkzeug und wurde regelmäßig für die Synthese von komplizierten Molekülen verwendet. Jedoch ist die weitere Reaktivität durch die Kompatibilität mit den Bedingungen, aus der die Metallhydridspzies gebildet wird, eingeschränkt. Durch die Einbringung der Photokatalyse oder Elektrochemie kommen mildere Methoden zum Vorschein, die völlig neue Reaktivitäten erschließen und Perspektiven schaffen diese Methoden in neue Richtungen auszubauen. Diese Zusammenfassung stellt die neusten Entwicklungen in elektro‐ und photochemisch Cobalt‐katalysierten Methodiken vor, und gibt eine Aussicht auf zukünftige Entwicklungen.