Formation of a Naphthalene Framework by Rhodium(III)-Catalyzed Double C–H Functionalization of Arenes with Alkynes: Impact of a Supporting Ligand and an Acid Additive.

An efficient protocol has been developed for the synthesis of larger condensed arenes from aromatic hydrocarbons and internal alkynes. This protocol uses readily available [CpRhI2 ]n as a catalyst and Cu(OAc)2 as an oxidant and proceeds smoothly through undirected double C–H activation. The addition of trifluoroacetic acid has a crucial positive impact on the reaction selectivity and the yields of the target products. In contrast to the previously reported catalytic systems, the new conditions allow the use of both dialkyl- and diarylacetylenes with the same high efficiency. [ABSTRACT FROM AUTHOR]