-Hydroarylation of Activated Internal Alkynes: Merging Pd and Energy Transfer Catalysis.

A general catalytic -hydroarylation of electron-deficient internal alkynes compatible with both electron-poor and electron-rich aryl reagents is reported. This selectivity is achieved through a sequential -carbopalladation of the alkyne by an Ar-Pd species, followed by a tandem, Ir-photocatalyzed, counter-thermodynamic → isomerization. The use of -substituted boronic acids enables direct access to pharmaceutically relevant heterocyclic cores via a cascade process. Mechanistic insight into the involvement of Ar-Pd versus Pd-H as an active species is provided.