Highly selective perfluoroalkylchalcogenation of alkynes by the combination of iodoperfluoroalkanes and organic dichalcogenides upon photoirradiation

Vinylic selenides and tellurides are useful synthetic intermediates for preparation of vinylic compounds and carbonyl compounds. Herein we report highly selective perfluoroalkylselenation and -telluration of terminal alkynes by using heteroatom mixed systems, i.e., (PhSe)2/RfI and (PhTe)2/RfI, upon photoirradiation. When the reaction of aromatic alkynes and conjugated enynes with diphenyl diselenide and perfluoroalkyl iodide is conducted in benzotrifluoride (BTF) as solvent upon irradiation with a xenon lamp through Pyrex (hν >300 nm), novel perfluoroalkylselenation of the alkynes takes place regio- and stereoselectively to give 1-(perfluoroalkyl)-2-(phenylseleno)alkenes in good yields. Similar procedure can be applied to photoinduced perfluoroalkyltelluration of aromatic alkynes, and perfluoroalkyl and phenyltelluro groups are introduced to the terminal and internal positions of alkynes regio- and stereoselectively. Since perfluoroalkyl (fluorous) groups make it possible to isolate the products easily by fluorous/organic/aqueous extraction technique, the obtained perfluoroalkylselenation and -telluration products are promising as synthetic intermediates.