Abstract
Introducing aryl- and heteroaryl moieties into
molecular scaffolds are often key steps in the syntheses of natural products, drugs, or functional materials. A variety of crosscoupling methods have been well established, mainly using transition metal mediated reactions between prefunctionalized substrates and arenes or C−H arylations with functionalization in only one coupling partner. Although ...
Abstract
Introducing aryl- and heteroaryl moieties into
molecular scaffolds are often key steps in the syntheses of natural products, drugs, or functional materials. A variety of crosscoupling methods have been well established, mainly using transition metal mediated reactions between prefunctionalized substrates and arenes or C−H arylations with functionalization in only one coupling partner. Although highly developed, one drawback of the established sp2−sp2 arylations is the required transition metal catalyst, often in combination with specific ligands and additives. Therefore, photoredox mediated arylation methods have been developed as alternative over the past decade. We begin our survey with visible light photo-Meerwein arylation reactions, which allow C−H arylation of heteroarenes, enones, alkenes, and alkynes with organic dyes, such as eosin Y, as the photocatalyst. A good number of examples from different groups illustrate the broad application of the reaction in synthetic transformations. While initially only photo-Meerwein arylation−elimination processes were reported, the reaction was later extended to photo-Meerwein arylation−addition reactions giving
access to the photoinduced three component synthesis of amides and esters from alkenes, aryl diazonium salts, nitriles or formamides, respectively. Other substrates with redox-active leaving groups have been explored in photocatalyzed arylation reactions, such as diaryliodonium and triarylsulfonium salts, and arylsulfonyl chlorides. We discus some examples with their scope and limitations.
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