Arenium cation as the key intermediate of the electrosynthesis of N-(2,5-dimethoxyphenyl)azoles. A new approach to the synthesis of N-(dimethoxyphenyl)azoles
作者:V. A. Petrosyan、A. V. Burasov
DOI:10.1007/s11172-007-0342-3
日期:2007.11
Data on the effect of the acid-base properties of the medium on the yield and composition of the products of N-dimethoxyphenylation of azoles (pyrazole, triazole, their substituted derivatives, and tetrazole) upon galvanostatic electrolysis of azole—1,4-dimethoxybenzene mixtures in nucleophilic (MeOH) and neutral (MeCN) media were considered and the trends of this process were discussed. The generation of arenium cations (1,4-dimethoxy-1-azolylbenzenium in MeCN and 1,1,4-trimethoxybenzenium in MeOH) as the key intermediates of electrosynthesis of N-(dimethoxyphenyl)azoles, was proved experimentally. A new approach to the synthesis of N-(dimethoxyphenyl)azoles through electrosynthesis of 1,1,4,4-tetramethoxycyclohexa-2,5-diene by electrooxidation of 1,4-dimethoxybenzene in MeOH as the first step and the reaction of this quinone diketal with azoles as the second step was suggested. The efficiency of this route to N-(dimethoxyphenyl)azoles is comparable with the efficiency of the purely electrochemical one-step process.
关于电解质介质的酸碱性质对氮二甲氧基苯化吡唑、三唑及其取代衍生物和四唑(统称为氮二甲氧基苯化唑类)在电化学恒流电解法制备产物产率和组成的影响的数据在亲核(甲醇)和中性(乙腈)介质中进行了考虑和讨论,并讨论了其过程趋势。通过实验证实了芳铵阳离子(乙腈中的1,4-二甲氧基-1-唑基苯铵和甲醇中的1,1,4-三甲氧基苯铵)作为氮(二甲氧基苯基)唑类电合成关键中间体的生成。提出了通过电合成1,4-二甲氧基苯在甲醇中的电氧化生成1,1,4,4-四甲氧基环己-2,5-二烯作为第一步,以及该醌二酮与唑类反应作为第二步的氮(二甲氧基苯基)唑类合成新途径。此途径的效率与纯电化学一步法相当。