Reaction of 1-chloroperfluorocycloalkene derivatives with nucleophiles

Abstract

1-Acetyl-2-chloroperfluorocycloalkenes and 1-benzoyl-2-chloroperfluorocycloalkenes have been prepared by the coupling of 2-chloroperfluorocycloalkenyl copper reagent with acetyl chloride and benzoyl chloride, respectively. Similarly, 1-chloro-2-( p-nitrophenyl)perfluoro-cyclopentene and -cyclohexene were prepared by the reaction of 2- chloroperfluorocyclo-pentenyl and -hexenyl copper reagent with p-nitroiodobenzene. The compounds contain not only highly activated double bonds but also charge-stabilizing groups in vinylic positions. The reaction of these compounds has been studied with various nucleophiles. They were very susceptible to nucleophilic attack at the chlorine-bonded carbon atom. Cyclobutene and cyclopentene derivatives underwent interesting nucleophilic displacement reactions of vinylic chlorine with alkoxide, amine and triethyl phosphite without allylic rearrangement under mild conditions. The stabilization effect to the generated carbanion intermediate by the acyl or p-nitrophenyl group undoubtedly dictates selectivity. However, additional factors must be considered in cyclohexene derivatives in which both ‘inward' and ‘outward' eliminations occur from methoxide ion attack on perfluoroacyclohexene derivatives. Also the order of activating power for a double bond has been found to be benzoyl > acetyl ⪢ p-nitrophenyl and 1-chlorotetfluorocyclobutene derivatives were more reactive than 1-chlorohexafluorocyclopentene derivatives towards the various nucleophiles.