Pd-Catalyzed Decarboxylative Ortho-Halogenation of Aryl Carboxylic Acids with Sodium Halide NaX Using Carboxyl as a Traceless Directing Group.

A highly regioselective Pd-catalyzed carboxyl directed decarboxylative ortho-C-H halogenation of cheap o-nitrobenzoic acids with NaX (X = I, Br) under aerobic conditions has been established. The utility of the method has been demonstrated by the gram-scale reaction and derivatization of the product. Experimental results have confirmed Pd and Bi played critical roles in the transformation and indicated the transformation might proceed via 2-halo-6-nitrobenzoic acid derivative intermediate.