Development of a new methodology for synthesis of symmetrical biaryls

Biaryls are the organic compounds with two benzene rings directly connected to each other. These compounds form the core of many pharmaceutical drugs, bioactive molecules, natural products, agrochemicals and polymers. Biaryl compounds are synthesized through coupling reactions with the aid of a metal catalyst. Palladium is widely used as a catalyst in the synthesis of the biaryls due to its functional group tolerance and inertness.;In our research a highly efficient new protocol for C-Te bond formation leading to symmetrical diaryl tellurides has been developed. It is a one-pot reaction which involves aryl iodides and elemental tellurium as starting materials in the presence of KOH without using any catalyst, as shown in the following scheme.;These synthetic diaryl tellurides will be used as the starting materials to generate biaryls under exceptionally mild conditions. The biaryls will be produced by the detelluration reaction on the diaryl tellurides using palladium(0) which is generated from commercially available and low cost PdCl2 and Na2CO3. The detelluration reaction is shown in the following scheme.;The biaryls synthesized by this novel technique resulted in good to excellent yields and the derivatives were characterized by 1H NMR. The new method to generate biaryls will lead to a more benign alternative to the field of pharmaceuticals in the synthesis of biaryl containing drugs.