Aromatic azapentalenes: 1H- and (mesoionic) 2H-pyrrolotetrazoles. Part 1. Synthesis and spectral characteristics
作者:Dietrich Moderhack、Dirk Decker、Bernhard Holtmann
DOI:10.1039/b007873p
日期:——
Two separate series of the title systems have been prepared by cyclisation of tetrazolium salts having acylmethyl functions attached to both the ring carbon and the adjacent nitrogen atom (3, 4): (i) working in an acetate buffer led to 7-acyl derivatives (5, 6; Scheme 3), and (ii) treatment with anhydride–base gave 5,7-diacyl compounds by a deviating ring closure mechanism (11, 12; Scheme 4). These materials could be defunctionalised to afford pyrrolotetrazoles (7, 8) which were earlier approached in vain from the respective 5-methyltetrazolium salts (Tschitschibabin reaction). Regarding characterisation data, attention is drawn to the conspicuous spectroscopic differences between the 1H- and the 2H-system. 2H-Pyrrolotetrazoles (6, 8, 12) represent a novel class of Ramsden’s ‘type C’ heteropentalene mesoions.
两系列独立的标题系统是通过环化含有酰基甲基功能团的叠氮盐制备的,这些功能团附着在环碳和相邻氮原子上(3,4):(i) 在醋酸盐缓冲液中反应得到了7-酰基衍生物(5,6;方案3),(ii) 与酸酐-碱的处理通过偏差的环闭合机制得到了5,7-二酰基化合物(11,12;方案4)。这些材料可以去功能化,最终得到吡咯并叠氮唑(7,8),而早期尝试通过相应的5-甲基叠氮盐(Tschitschibabin反应)得到这些化合物则未能成功。关于表征数据,特别需要注意的是1H系统和2H系统之间显著的光谱差异。2H-吡咯并叠氮唑(6,8,12)代表了一类新型的Ramsden“C型”杂五苯的中间离子。