1-Aryl-F-1,3-butadienes and Unsymmetrical α,ω-Diaryl-F-polyenes

Para-substituted 1-aryl-F-1,3-butadiene derivatives p-R-C₆H₄-CFCFCFCF₂ (2a−g), where R = H, CH₃, OCH₃, OC₆H₁₁, N(CH₃)₂, Br, and CF₃, have been prepared by reaction of appropriate arylmagnesium bromides with F-1,3-butadiene. ¹⁹F NMR chemical shifts correlate with σ_p Hammett substituent constants. Compounds 2a−e react on their terminal perfluorovinyl group with C-nucleophiles and were used as intermediates in subsequent reactions with suitable organolithium compounds for the synthesis of a new series of unsymmetrically substituted α,ω-diaryl-F-polyenes RC₆H₄(CFCF)_nC₆H₄R‘, where n = 2 or 3 and R‘ is one of the substituents specified above. A variety of new synthons containing α,ω-diaryl-F-1,3-butadiene skeleton and reactive Br, OH, CHO, and COOH functionalities in para-positions on aromatic rings has been also prepared. Structural aspects, NMR spectra, and mesogenic properties of the title compounds are discussed.