Facile preparation of α,ω-diynes bearing a perfluoroalkylene linker –(CF2)n– (n = 4,6) and their application for Co- or Rh-catalyzed [2+2+2]cycloaddition reactions affording aromatic compounds with perfluoroalkylene units

Abstract

α,ω-Diynes bearing a perfluoroalkylene linker HC≡C(CF2)nC≡H (n = 4,6) were obtained from commercially available α,ω-dienes H2C=CH(CF2)nCH=CH2 via bromination and dehydrobromination. In the presence of CoCl2-Zn-ZnI2 catalyst, the diyne HC≡C(CF2)4C≡H underwent [2+2+2] cycloaddition reactions with terminal alkynes to afford benzene derivatives fused with an octafluorocyclohexene moiety. In this reaction, trimerization of the diyne was observed as a major side reaction. Rh-catalyzed aromatization polymerization of the diyne HC≡C(CF2)6C≡H afforded an insoluble polymer consisting of a densely cross-linked, aromatic skeleton, which was characterized by solid-state CP-MAS 13C NMR and IR spectroscopy. This insoluble polymer exhibited high thermal stability, and engineering applications of the product polymer are being evaluated.