Progressive Direct Iodination of Sterically Hindered Alkyl Substituted Benzenes

Benzene derivatives bearing at least one bulky alkyl group (i-Pr or t-Bu) were selectively and effectively iodinated using elemental iodine activated by 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (SelectfluorTM, F-TEDA-BF4). Iodine atoms were progressively introduced at the most electron-rich and sterically less hindered position on the benzene ring. Not more than three iodine atoms could be progressively bonded to a target molecule bearing a i-Pr or t-Bu group.