The 5-endo-trig Cyclization of gem-Difluoroolefins with sp3 Carbon Nucleophiles: Synthesis of 1-Fluorocyclopentenes

Abstract
A disfavored 5-endo-trig cyclization is accomplished in gem-difluoroolefins with sp3 carbon nucleophiles, generated via the lithium–iodine exchange reaction of 1,1-difluoro-5-iodo-1-pentenes with tert-butyllithium, to afford 1-fluorocyclopentenes.