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 discov-ery and development process along with their applications as agrochemicals, fungicides, herbi-cides, etc., making them the most prevalent form of biologically relevant molecules. Hence, enor-mous efforts have been made to flourish green routes for their high-yielding synthesis under mi-crowave 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.