Rhodium(III) and hexabromobenzene-a catalyst system for the cross-dehydrogenative coupling of simple arenes and heterocycles with arenes bearing directing groups.

C(6)Br(six) & drugs! C(6)Br(6) can be used as the cooxidant/catalyst modifier for the [Rh(III)Cp*]-catalyzed (Cp*=C(5)Me(5)) dehydrogenative cross-coupling of benzamides with simple benzene derivatives (see scheme, DG=directing group). Similarly, heterocycles can be coupled and druglike structures formed. Mechanistic studies suggest a unique and multiple role of the Cu(OAc)(2)/C(6)Br(6) system and a nonchelate-assisted C-H activation as the rate-determing step.