Ir(III)-Catalyzed Aromatic C–H Bond Functionalization via Metal Carbene Migratory Insertion

Ir­(III)-catalyzed
coupling of aromatic C–H bonds with diazomalonates
has been achieved successfully via a metal carbene migratory insertion
process. With different types of carbamoyl directing groups, a wide
range of arenes, including heteroarenes, can be used as substrates
in this Ir­(III)-catalyzed C–H functionalization reaction. Mono-
and bisfunctionalized products can be obtained selectively simply
by changing the number of equivalents of the diazo substrate. Moreover,
when diazomalonates bearing one or two tert-butyl
groups are used as the substrates, the C–H bond functionalization
is followed by decarboxyation, leading to products with a −CH2CO2Me or −CH2CO2H
moiety at the position ortho to the directing group.
This reaction demonstrates that direct C–H activation and the
metal carbene migratory insertion can be merged into one catalytic
cycle with an Ir­(III) complex as the catalyst.