Monodentate Transient Directing Group Assisted Pd-Catalyzed Direct Dehydrogenative Cross-Coupling of Benzaldehydes with Arenes toward 9‑Fluorenones

Commercially available
3,5-bis­(trifluoromethyl)­aniline was found
to be a highly efficient monodentate transient directing group (MonoTDG)
for the palladium-catalyzed direct dehydrogenative cross-coupling
of benzaldehydes with arenes. A diverse set of symmetrical and unsymmetrical
9-fluorenones was readily obtained in yields of 32–72% along
with excellent regioselectivities and broad functional group compatibility
as well as high atom economy under mild conditions via a dual carbon–hydrogen
(C–H) bond activation sequence.