Synthesis of 4‑Selanyl- and 4‑Tellanyl‑1<i>H</i>‑isochromen-1-ones Promoted by Diorganyl Dichalcogenides and Oxone

A new method was developed for the synthesis of 4-chalcogenyl-1H-isochromen-1-ones through the 6-endo-dig electrophilic cyclization of 2-alkynylaryl esters and diorganyl dichalcogenides under ultrasound irradiation. The reactions were performed under mild conditions, using Oxone as a green oxidant to promote the cleavage of the chalcogen–chalcogen bond in diorganyl diselenides and ditellurides to generate electrophilic species in situ. A total of 25 compounds were selectively obtained after 30–70 min, in good to excellent yields (74–95%). This procedure was extended to prepare 5H-selenopheno­[3,2-c]­isochromen-5-ones. Additionally, for the first time, the 4-chalcogenyl-1H-isochromen-1-ones were used as substrates in the thionation reaction, using Lawesson’s reagent and microwave irradiation under solvent-free conditions, obtaining the thio derivatives in yields of up to 99% in only 15 min.