Synthesis of Fluorine Containing Polyfunctional Aromatic Compounds
--Sandmeyer Synthesis of 4-Halo-trifluoromethylbenzonitriles--

Tetsuo HINO, Tsutomu NAMIE††, Hiroyuki NAKAMURA and Noriyuki YONEZAWA*

Department of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture and Technology; Koganei-shi 184-8588 Japan
Present Address: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo; Hongo, Bunkyo-ku, Tokyo 113-8656 Japan
†† Department of Chemistry, Gunma University; Kiryu-shi 376-8515 Japan

An effective synthesis of a series of fluorine-containing polyfunctional aromatic compounds, 4-halo-3-trifluoromethylbenzonitriles 1a--c was performed by the use of some tetrahedral copper-cyano complexes as Sandmeyer cyanating reagents and sublimation in the isolation and purification process. In the conversion of the corresponding diazonium salts to the target benzonitrile derivatives (1a--c), three tetrahedral tetracyanocopper complexes, K3[Cu (CN)4], Na3[Cu (CN)4], and K2[Cu (CN)4ENH3], proved to be effective as Sandmeyer cyanating reagents though copper (I) cyanide gave the target compounds in moderate yields. Furthermore, the yields of nitriles 1a--c in the reaction with the copper (I) complexes were rather higher than that with the copper (II) complex, K2[Cu (CN)4ENH3]. The conversion reactions to nitriles 1a--c are suggested to proceed through an SNAr mechanism.

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