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.
Key words
acenes - C–H activation - homologation - non-chelate-assisted C–H functionalization
- rhodium catalysis