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Despite significant progress in aliphatic decarboxylation, an efficient and general protocol for radical aromatic decarboxylation has lagged far behind. Herein, we describe a general strategy for rapid access to both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters followed by their successive use in divergent carbon–heteroatom and carbon–carbon bond‐forming reactions. Identification of a suitable activator for carboxylic acids is the key to bypass a competing single‐electron‐transfer mechanism and "switch on" an energy‐transfer‐mediated homolysis of unsymmetrical σ‐bonds for a concerted fragmentation/decarboxylation process. [ABSTRACT FROM AUTHOR]

The development of new hydrogen-atom transfer (HAT) strategies within the framework of photoredox catalysis is highly appealing for its power to activate a desired C−H bond in the substrate leading to its selective functionalization. Reported here is the first photoredox-mediated hydrogen-atom transfer method for the efficient synthesis of ynones, ynamides, and ynoates with high regio- and chemoselectivity by direct functionalization of C [ABSTRACT FROM AUTHOR]

Die Entwicklung neuer Wasserstoffatomtransfer(HAT) ‐ Strategien im Kontext der Photoredoxkatalyse stellt eine hochattraktive Möglichkeit zur gezielten Aktivierung einer C ‐ H ‐ Bindung eines Substrats mit anschließender selektiver Funktionalisierung dar. Wir beschreiben hier das erste Photoredox ‐ vermittelte Wasserstoffatomtransfer ‐ Protokoll zur hoch regio ‐ und chemoselektiven Synthese von Inonen, Inamiden und Inestern, erreicht durch direkte Funktionalisierung von Csp2 (O) ‐ H ‐ Bindungen. Die weitreichenden Anwendungsmöglichkeiten dieser Methode wurden im Rahmen der selektiven Funktionalisierung von C(O) ‐ H ‐ Bindungen in hochkomplexen Molekülgerüsten verdeutlicht. HAT was: Ein Photoredox ‐ katalysierter Wasserstoffatomtransfer zur Erzeugung von Carbonylradikalen ausgehend von Aldehyden und analogen Substraten mit XC(O) ‐ H ‐ Funktionalitäten (X=N, O) wurde entwickelt. Die Funktionalisierung der Carbonylradikale mit Ethinylbenziodoxolon(EBX) ‐ Reagenzien führte zur Synthese komplexer Inone, Inamide und Inester ausgehend von leicht verfügbaren Startmaterialien. [ABSTRACT FROM AUTHOR]

Selective functionalization of ubiquitous C(sp3)-H bonds using visible light is a highly challenging yet desirable goal in organic synthesis. The development of such processes relies on both rational design and serendipitous discoveries from innovative tools such as screening technologies. Applying a mechanism-based screening strategy, we herein report photoredox-mediated hydrogen atom transfer catalysis for the selective activation of otherwise unactivated C(sp3)-H bonds, followed by their trifluoromethylthiolation, which has high potential as a late-stage functionalization tool. The generality of this method is exhibited through incorporation of the trifluoromethylthio group in a large number of C(sp3)-H bonds with high selectivity without the need for an excess of valuable substrate. [ABSTRACT FROM AUTHOR]

Herein is reported the catalytic, visible light-promoted, decarboxylative halogenation (bromination, chlorination, and iodination) of aliphatic carboxylic acids. This operationally-simple reaction tolerates a range of functional groups, proceeds at room temperature, and is redox neutral. By employing an iridium photocatalyst in concert with a halogen atom source, the use of stoichiometric metals such as silver, mercury, thallium, and lead can be circumvented. This reaction grants access to valuable synthetic building blocks from the large pool of cheap, readily available carboxylic acids. [ABSTRACT FROM AUTHOR]