Synthese von heterocyclen. V. 1, 3, 4-thiadiazol-2 (3H)-one
作者:Haukur Kristinsson、Tammo Winkler
DOI:10.1002/hlca.19820650833
日期:1982.12.15
A new and highly versatile method for the synthesis of 1, 3, 4-thiadiazol-2 (3 H)ones 1 is described. Methoxy-1,3,4-thiadiazoles- 5, which are readily available by condensation of O-methyl thiocarbazate (2) with acid derivatives 3, undergo an efficient cleavage to 1 and methyl chloride with hydrochloric acid in an anhydrous medium. Many new 5-substituted thiadiazolones, unavailable by earlier routes
描述了一种合成1,3,4-噻二唑-2(3 H)ones 1的新方法,该方法用途广泛。甲氧基-1,3,4-噻二唑-5(可通过将O-甲基硫代氨基甲酸酯(2)与酸衍生物3缩合而容易获得)在无水介质中有效裂解为1,并用盐酸将其分解为氯甲烷。合成了许多新的5-取代的噻二唑酮,较早的途径无法获得。讨论了制备方面和机理方面。借助13 C-NMR。光谱学,1的互变异构研究表明,互变异构平衡取决于5-位取代基的性质。噻二唑酮1主要以氧代形式存在。然而,羟基形式的百分比随着在5-位的强烈吸电子取代基而增加。用对甲良好的相关性ķ一个观察和σ值- 。