The Sonogashira reaction is a cross-coupling reaction used in organic synthesis to form carbon–carbon bonds. It employs a palladium catalyst to form a carbon–carbon bond between an aryl or vinyl halide and a terminal alkyne. Due to its usefulness in the formation of carbon–carbon bonds, the Sonogashira cross-coupling reaction has been employed in a wide variety of areas such as pharmaceuticals, natural products, organic materials, and nanomaterials. Organochalcogen compounds have been used extensively in carbon–carbon bond forming reactions. In our research, a highly efficient new protocol for C-Te bond formation leading to symmetrical diaryl tellurides has been developed. The synthesis of symmetrical diaryl tellurides employed aryl iodides and elemental tellurium as starting materials in the presence of KOH. It is a one-pot reaction without using any catalyst. Utilizing this new protocol, a variety of aryl and heteroaryl iodides are reacted with elemental tellurium to afford the corresponding diaryl tellurides in good to excellent yields. In this work, diaryl tellurides were used as coupling partners in Pd-catalyzed Sonogashira reactions under exceptionally mild conditions. Several palladium catalysts and bases were attempted but the coupling product alkynyl arene was formed in a favorable yield at room temperature only when Pd(dppf)Cl2 was used as the palladium source and K2CO3 as the base in the presence of CuI. Under the optimized conditions, the coupling between various diaryl tellurides with alkynes was studied. The new method for Sonogashira reactions will lead to a more benign alternative to the various fields in the synthesis of alkynyl arene-containing molecules.

Palladium-catalyzed Songashira coupling reaction between diaryl telluride and alkyes

249th National Meeting (2015)

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