Palladium Nanoparticles on Graphite Oxide: A Recyclable Catalyst for the Synthesis of Biaryl Cores

Abstract

The synthesis of life saving drug molecules in a cost-effective and environmentally benign pathway is of paramount significance. We present an environment friendly protocol to prepare core moieties of top selling drug molecules such as boscalid and telmisartan using Suzuki–Miyaura coupling conditions. In contrast to the traditional synthesis of these pharmaceutically important molecules, we have accomplished a graphite oxide (GO) supported palladium nanoparticles (PdNPs) based catalyst which quantitatively produced these core biaryl moieties of top selling drug molecules in a recyclable way. The catalytic activity remained unchanged even after 16 successive catalytic cycles without incorporating any palladium metal impurity in the pharmaceutically significant organic products. A detailed study including IR spectroscopy, solid state NMR spectroscopy, X-ray photoelectron spectroscopy, and DFT calculation was employed to understand the role of solid support on the nondecaying recycling ability of the catalyst during the Suzuki–Miyaura coupling reaction. The study indicates a strong chemical interaction of the different functionalities present in the GO, with the palladium centers which is primarily responsible for such sustained catalytic activity during the consecutive Suzuki–Miyaura coupling cycles.