A reagent-free electrochemical synthesis of valuable 1,2,4-triazolo[4,3-a]pyridines and related heterocycles was developed.

A novel ligand-free Pd-catalyzed cascade reaction between o-chlorobenzoic acids and cyclic diaryliodonium salts is reported. This one-pot procedure involves a carboxylic acid directed o-arylation followed by intramolecular decarboxylative annulation affording various valuable triphenylenes, which can be further transformed into diversified building blocks for material chemistry. For the first time, it was shown that an aromatic halide can react with diaryliodonium salts under the direction of carboxylic acid functionality. It was also demonstrated that the carboxylic acid could be employed as both a traceless directing group and functional handle for the atom- and step-economical one-pot double cross-coupling annulation reaction with cyclic diaryliodonium salts as the π-extending agents.

Here we report a site-selective synthesis of functionalized dibenzo[f,h]quinolines and their derivatives, which could be used as OLED materials. The key step is the double cross coupling reaction between the 2-chloropyridinyl acids and the cyclic diaryliodonium salts, where the carboxylic acid was unprecedentedly employed as both a traceless directing group and a functional handle in a one-pot atom- and step-economical process.