Microwave-Assisted Synthesis of Biologically Relevant Six-Membered N-Heterocycles

One of the most efficient non-conventional heating methods is microwave irradiation. In organic synthesis, microwave irradiation has become a popular heating technique as it enhances product yields and purities, reduces reaction time from hours to minutes, and decreases unwanted side reactions. Microwave-assisted organic synthesis utilizes dielectric volumetric heating as an alternative activation method, which results in rapid and more selective transformations because of the uniform heat distribution. Heterocyclic compounds have a profound role in the drug discovery and development process along with their applications as agrochemicals, fungicides, herbicides, etc., making them the most prevalent form of biologically relevant molecules. Hence, enormous efforts have been made to flourish green routes for their high-yielding synthesis under microwave irradiation as a sustainable tool. Among the different clinical applications, heterocyclic compounds have received considerable attention as anti-cancer agents. Heterocyclic moieties have always been core parts of the development of anti-cancer drugs, including market-selling drugs, i.e., 5-fluorouracil, doxorubicin, methotrexate, daunorubicin, etc., and natural alkaloids, such as vinblastine and vincristine. In this review, we focus on the developments in the microwave-assisted synthesis of heterocycles and the anti-cancer activities of particular heterocycles.