Syntheses of 1-aryl-2-trifluoromethylbenzimidazoles via electrochemically prepared p-benzoquinone imines
摘要:
Electrooxidation of N-(4-methoxyphenyl)-N'-aryl-2,2,2-trifluoroethanimidamides 1 in an MeCN-H2O-NaClO4-(C)-(Pt) system affords p-benzoquinone imines 2 which are converted to 1-aryl-2-trifluoromethylbenzimidazoles 3 by acid catalyzed cyclization.
Electrochemical Oxidation of N,N'-Disubstituted Trifluoroethanimidamides. An Approach to N-Substituted 2-(Trifluoromethyl)benzimidazoles
摘要:
Electrochemical oxidation of N,N'-disubstituted trifluoroethanimidamides 11 in dry acetonitrile and in aqueous acetonitrile provided N-substituted 2-(trifluoromethyl)benzimidazoles 15 and N-1-(4-oxo-2,5-cyclohexadien-1-ylidene)-N-2-substituted-2,2,2-trifluoroethanimidamides (p-benzoquinone imine derivatives) 20, respectively. In dry acetonitrile, electron-donating para substituents in the N,N'-diaryl derivatives strongly promoted the formation of benzimidazoles, whereas N-alkyl-N'(4-methoxyphenyl) derivatives provided rather complex mixtures of 11,20, and polymeric compounds. In wet acetonitrile, p-benzoquinone imines 20 were major products regardless of the substituents. An ECEC process via two-electron oxidation is proposed.
Electrochemical Oxidation of N,N'-Disubstituted Trifluoroethanimidamides. An Approach to N-Substituted 2-(Trifluoromethyl)benzimidazoles
作者:Kenji Uneyama、Masafumi Kobayashi
DOI:10.1021/jo00090a017
日期:1994.6
Electrochemical oxidation of N,N'-disubstituted trifluoroethanimidamides 11 in dry acetonitrile and in aqueous acetonitrile provided N-substituted 2-(trifluoromethyl)benzimidazoles 15 and N-1-(4-oxo-2,5-cyclohexadien-1-ylidene)-N-2-substituted-2,2,2-trifluoroethanimidamides (p-benzoquinone imine derivatives) 20, respectively. In dry acetonitrile, electron-donating para substituents in the N,N'-diaryl derivatives strongly promoted the formation of benzimidazoles, whereas N-alkyl-N'(4-methoxyphenyl) derivatives provided rather complex mixtures of 11,20, and polymeric compounds. In wet acetonitrile, p-benzoquinone imines 20 were major products regardless of the substituents. An ECEC process via two-electron oxidation is proposed.
Syntheses of 1-aryl-2-trifluoromethylbenzimidazoles via electrochemically prepared p-benzoquinone imines
作者:Kenji Uneyama、Masafumi Kobayashi
DOI:10.1016/s0040-4039(00)79443-3
日期:1991.10
Electrooxidation of N-(4-methoxyphenyl)-N'-aryl-2,2,2-trifluoroethanimidamides 1 in an MeCN-H2O-NaClO4-(C)-(Pt) system affords p-benzoquinone imines 2 which are converted to 1-aryl-2-trifluoromethylbenzimidazoles 3 by acid catalyzed cyclization.