Recent advances in the synthesis of organoselenium heterocycle conjugates

Selenium (Se) is a crucial micronutrient essential for the human body, playing a critical function in antioxidant protection and immune system function. The chemical and organic properties of organoselenium (OSe) compounds have drawn much attention in medicinal, agrochemical, and materials sciences. OSe compounds have shown superior pharmaceutical properties to their sulfur analogs and featured significant activities in chemotherapy, material sciences, catalysis, and coordination chemistry. Incorporating Se atoms into a heterocyclic backbone has resulted in scaffolds with interesting physicochemical and medicinal properties. Se-containing heterocycles may be synthesized via selenylation reactions, selenofunctionalization of pre-existing heterocycles, or cyclization through Se-mediated mechanisms. These strategies offered numerous opportunities to design and improve novel Se-bearing heterocycles with promising pharmaceutical activities. This review highlights the latest development in synthesizing organylselenyl substituted three-, four-, and five-membered ring heterocycles, which are rapidly growing research. A particular focus is paid to the used synthetic strategies, selenylating reagents, scopes, and limitations of this reaction, as well as the plausible mechanism. The protocols employing diorganyl diselenides, elemental Se, and electrophilic Se as Se sources were thoroughly discussed and covered. This review paves the way for future research in developing new heterocycles and opens a new era for the latestage seleno-functionalization of bioactive and naturally occurring compounds.