Selenoxanthylium Salts Synthesized from Selenoethers and Their Electronic Structures

A Lewis/Brønsted acid-promoted intramolecular cyclization of diarylselenoethers bearing formyl groups afforded novel selenoxanthylium salts in good yield. The electronic structures of these selenoxanthylium salts were determined using NMR and UV–vis absorption spectroscopy techniques as well as DFT calculations. The obtained results clearly imply effective conjugation of the π-electrons throughout the entire fused selenium-containing heterocyclic framework.