An overview of palladium-catalyzed synthesis of seven-membered heterocycles

Heterocyclic compounds are the ones that have always remained in the limelight owing to their superior contributions toward various disciplines such as biology, medicine, material science, pharmaceutical science, industry and so on. They form the building blocks of DNA and RNA macromolecules. Suitable tuning of these heterocyclic compounds can result in chemotherapeutic moieties with superlative efficiency. Seven-membered heterocyclic compounds are an important class of heterocyclic chemistry. Some of them are azepine, oxepine, thiepine, diazepine, thiazepine and so on. Transition metal-catalyzed synthesis of heterocycles has been the most explored in the recent past. Palladium is known as the best suitable catalyst for the same and that is the result of its excellent functional group tolerance and catalytic potency. Here, we intend to summarize the various investigations made on the palladium-catalyzed synthesis of seven-membered heterocycles. To the best of our knowledge, this is the first review in this topic and covers literature up to 2020.