Bicyclic [<i>b</i>]-heteroannulated pyridazine derivatives. 9. cyclization reactions of 4,4-dimethyl- and 4-phenyltetrahydropyridazine-3,6-dione 3-hydrazones with esters of keto dicarboxylic acids
Bis(ethoxycarbonyl)alkylidene derivatives 4 and 5 of the respective title hydrazones were obtained in the reactions with diethyl oxomalonate, diethyl oxosuccinate, diethyl 2-oxoglutarate, and diethyl oxalo-propionate as mixtures of geometric isomers with high predominance of one of them. On heating at 160-200° without any solvent or on refluxing in ethanol 4 cyclized to yield the corresponding pyri-dazino[6
在与高马酸二乙酯,氧代丁二酸二乙酯,2-氧代戊二酸二乙酯和草酸丙二酸二乙酯的混合物中,以较高的几何异构体的混合物形式得到了各自标题的双(乙氧羰基)亚烷基衍生物4和5。上在160-200°加热无任何溶剂或在乙醇中回流4环化,得到相应的螨-dazino [6,1- Ç ]三嗪6,而对其进行加热5得到,取决于链长,相应pyra-唑基哒嗪8b和8d或哒嗪基哒嗪8c。用X射线分析确定6和8的结构。发现6c的晶胞可容纳代表四个构象变体的16个分子。4和5在环化反应中的不同行为是根据互变异构平衡来解释的,互变异构平衡在4中向烯胺形式转变,在5中向亚胺形式转变。在1 H nmr光谱中,远距离手性效应在4d和5a-d中的传输表现为一个或两个酯乙基中CH 2质子的磁性不等价。