An efficient synthesis of fluorocyclopentenes using fluoroalkylidenecarbenes

An efficient synthesis of fluorocyclopentenes is described. By treatment of (2-fluoroalkenyl)iodonium salts with potassium tert-butoxide, (α-fluoroalkylidene)carbenes were generated efficiently to give fluorocyclopentenes via 1,5-C-H insertion. Fluorocyclopentenes having a functionality, such as chlorine, acetoxy, or ketone, and a spiro fluorocyclopentene were synthesized in good yields.