Behaviour of 5,6-dihydrothieno[2,3-<i>h</i>]cinnolin-3(2<i>H</i>)-one and 5,6-dihydrothieno[3,2-<i>h</i>]cinnolin-3(2<i>H</i>)-one towards hydrazine. Synthesis of thienocinnolinones and of 4-aminothienocinnolinones
作者:Stefania Villa、Giorgio Cignarella、Michela M. Curzu、Gérard A. Pinna、Elena Pini、Lucio Toma
DOI:10.1002/jhet.5570360523
日期:1999.9
isomeric compounds 5,6-dihydrothieno[2,3-h]cinnolin-3(2H)-one (7a) and 5,6-dihydrothieno-[3,2-h]cinnolin-3(2H)-one (7b) rapidly tautomerise to the corresponding 1,4-dihydrothienocinnolinones 8a,b when kept in refluxing hydrazine hydrate. With longer reaction times the initially formed 8a,b dehydrogenate to the thienocinnolinones 9a,b which eventually are aminated to 4-aminothienocinnolinones 10a,b. This behaviour
异构体化合物5,6-二氢噻吩并[2,3- h ] cinnolin-3(2 H)-one(7a)和5,6-二氢噻吩并[[3,2 - h ] cinnolin-3(2 H)-one (7b)当保持在回流的水合肼中时,迅速地互变异构成相应的1,4-二氢噻吩并噻吩啉酮8a,b。随着较长的反应时间,最初形成的8a,b脱氢成噻吩并噻吩酮9a,b,最终胺化为4-氨基噻吩并噻吩酮10a,b。此行为回想起有关5,6-dihydrobenzocinnolin-3(2 H)-one(1)在相同条件下经历脱氢反应生成苯并[ h ]肉桂醇-3(2 H)-一(2),然后进行4胺化至3,但中间体的稳定性,最终胺化的机理有所不同,并获得更高的反应速率。所有这些差异可以根据两个系列的转化的中间体和产物的形成热来合理化。