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

Abstract

This work is dedicated to Prof. Ernesto Carmona a mentor, friend, and colleague.The bis(silyl)triazene compound 2,6-(Me 3 Si) 2 -4-Me-1-(N¼NÀNC 4 H 8 )C 6 H 2 (4) was synthesized by double lithiation/silylation of 2,6-Br 2 -4-Me-1-(N¼NÀNC 4 H 8 )C 6 H 2 (1). Furthermore, 2,6-bis[3,5-(CF 3 ) 2 -C 6 H 3 ]-4-Me-C 6 H 2 -1-(N¼NÀNC 4 H 8 )C 6 H 2 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 I 2 afforded in good yields novel phenyl derivatives, 2,6-(Me 3 Si) 2 -4-MeC 6 H 2 ÀI and 2,6-bis[3,5-(CF 3 ) 2 ÀC 6 H 3 ]-4-MeC 6 H 2 ÀI (5 and 7, resp.). On the other hand, the analogous m-terphenyl 1,3-diphenylbenzene compound 2,6-bis[3,5-(CF 3 ) 2 ÀC 6 H 3 ]C 6 H 3 ÀI (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 I 2 . Different attempts to introduce the t Bu (Me 3 C) or neophyl (PhC(Me) 2 CH 2 ) 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.