Synthesis and Characterization of m-Terphenyl (1,3-Diphenylbenzene) Compounds Containing Trifluoromethyl Groups.

The bis(silyl)triazene compound 2,6-(Me₃Si)₂-4-Me-1-(NNNC₄H₈)C₆H₂ ( 4) was synthesized by double lithiation/silylation of 2,6-Br₂-4-Me-1-(NNNC₄H₈)C₆H₂ ( 1). Furthermore, 2,6-bis[3,5-(CF₃)₂-C₆H₃]-4-Me-C₆H₂-1-(NNNC₄H₈)C₆H₂ derivative 6 can be easily synthesized by a C,C-bond formation reaction of 1 with the corresponding aryl- Grignard reagent, i.e., 3,5-bis[(trifluoromethyl)phenyl]magnesium bromide. Reactions of compound 4 with KI and 6 with I₂ afforded in good yields novel phenyl derivatives, 2,6-(Me₃Si)₂-4-MeC₆H₂I and 2,6-bis[3,5-(CF₃)₂C₆H₃]-4-MeC₆H₂I ( 5 and 7, resp.). On the other hand, the analogous m-terphenyl 1,3-diphenylbenzene compound 2,6-bis[3,5-(CF₃)₂C₆H₃]C₆H₃I ( 8) could be obtained in moderate yield from the reaction of (2,6-dichlorophenyl)lithium and 2 equiv. of aryl- Grignard reagent, followed by the reaction with I₂. Different attempts to introduce the ^tBu (Me₃C) or neophyl (PhC(Me)₂CH₂) substituents in the central ring were unsuccessful. All the compounds were fully characterized by elemental analysis, melting point, IR and NMR spectroscopy. The structure of compound 6 was corroborated by single-crystal X-ray diffraction measurements. [ABSTRACT FROM AUTHOR]