Recent advances in the chemistry of Selenophenopyran, Selenophenochromene and Selenophenoisochromene Heterocycles: Synthesis, Reactivity, and Biological Activity

Selenophene, pyran, chromene, and isochromene are invaluable heterocyclic compounds, playing a crucial role in the development of novel drug molecules. The fusion of selenophene with 2H-pyran, 2H-chromene, 4H-chromene, or 1H-isochromene frameworks in hybrid structures has opened new avenues for pharmacological applications. This has led to the synthesis of selenophenopyran, selenophenochromene, and selenophenoisochromene derivatives, each exhibiting remarkable properties. The synthesis of selenophenopyran can be accomplished through a variety of chemical pathways, including Thorpe–Ziegler cyclization, Sonogashira and Suzuki cross-coupling reactions, as well as FeCl₃ /oxone and dialkyl diselenides-promoted intramolecular cascade cyclization of ortho-diynyl benzyl selenides. Additionally, the electrophilic cyclization of 3-iodo-4-seleno-2H-chromene using I₂/NaHCO₃ is also discussed. Furthermore, a molybdenum(V)-mediated method for switching the C(sp)-Se bond of phenylselenyl-functionalized arenes has been reported.