Palladium-Catalyzed Direct Ortho-C-H Selenylation of Benzaldehydes Using Benzidine as a Transient Directing Group.

Benzidine was found to be a novel transient directing group to enable Pd-catalyzed direct selenylation of inert C(sp2)-H bonds of benzaldehydes. Diverse diarylselenides were readily constructed in high efficiency and satisfactory yields with good functional group tolerance. The practical usage of the method was further demonstrated by enlarged reaction to gram scale and application in the facile access to two selenoxanthenes and one fluorescent probe.