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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]

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]

The title reaction is achieved in the presence of a typical iridium photocatalyst and various substrates are tolerable. [ABSTRACT FROM AUTHOR]