Iridium- and Rhodium-Catalyzed Directed C–H Heteroarylation of Benzaldehydes with Benziodoxolone Hypervalent Iodine Reagents

The C–H heteroarylation
of benzaldehydes with indoles and
pyrroles was realized using the benziodoxolone hypervalent iodine
reagents indole- and pyrroleBX. Functionalization of the aldehyde
C–H bond using either an o-hydroxy or amino
directing group and catalyzed by an iridium or a rhodium complex allowed
the synthesis of salicyloylindoles and (2-sulfonamino)­benzoylindoles,
respectively, with good to excellent yields (74–98%). This
new transformation could be carried out under mild conditions (rt
to 40 °C) and tolerated a broad range of functionalities, such
as ethers, halogens, carbonyls, or nitro groups.