The synthesis of a wide variety of 9-substituted-3-oxo-3H-2,9-dihydropyridazino[3,4,5-de]phthalazines (11) was achieved by treatment of 3-substituted-3,4-dihydro-4-oxophthalazine-5-carboxylic esters (10) with hydrazine hydrate. These esters were prepared from 3-hydroxyphthalide-7-carboxylic acid (7) by two different routes. Under basic conditions, alkylation of 3-oxo-3H-2,9-dihydropyridazino[3,4,5-de]phthalazine (1) gave 9-substituted products. These undergo further alkylation at the 2-position. Some of them were converted to 3-chloro, 3-thiono, and 3-hydrazino compounds by standard methods. Dehalogenation of selected 3-chloro compounds or desulphurization of 3-thiono derivatives gave 1-substituted-1H-pyridazino[3,4,5-de]phthalazines (22), some of which were also prepared by direct alkylation of the parent heterocycle 2 under basic conditions. However, treatment of 2 or its 1-methyl homologue with methyl iodide resulted in products in which nitrogen attached to carbon had been attacked rather than the 1- or 9-position. Treatment of the acid chloride of 3,4-dihydro-4-oxophthalazine-5-carboxylic acid with methyl hydrazine led to 2-methyl-3-oxo-3H-2,9-dihydropyridazino[3,4,5-de]phfhalazine (21a) which was purified by cyanoethylation at the 9-position, recrystallization, and hydrazinolysis of the cyanoethyl group. Biological testing revealed that many of the compounds lowered blood pressure in animal models but none had a sufficient therapeutic ratio of activity vs. side effects to warrant clinical trial.
一种广泛的9-取代-3-氧代-3H-2,9-二氢吡啶并[3,4,5-de]邻苯二氮酮(11)的合成是通过将3-取代-3,4-二氢-4-氧代邻苯二酮-5-羧酸酯(10)与水合肼处理而实现的。这些酯是通过两种不同的途径从3-羟基邻苯二酮-7-羧酸(7)制备的。在碱性条件下,3-氧代-3H-2,9-二氢吡啶并[3,4,5-de]邻苯二酮(1)的烷基化产生了9-取代产物。这些产物在2-位进一步发生烷基化。其中一些经过标准方法转化为3-氯、3-硫代和3-肼基化合物。选择性去卤化3-氯化合物或去硫化3-硫代衍生物得到1-取代-1H-吡啶并[3,4,5-de]邻苯二氮酮(22),其中一些也是通过在碱性条件下直接烷基化母环2制备的。然而,用碘甲烷处理2或其1-甲基同分异构体的结果是氮连接到碳而不是1-位或9-位。用甲基肼处理3,4-二氢-4-氧代邻苯二酮-5-羧酸酰氯导致2-甲基-3-氧代-3H-2,9-二氢吡啶并[3,4,5-de]邻苯二氮酮(21a),通过在9-位进行氰基乙基化、再结晶和氰基乙基基团的肼解纯化。生物测试显示许多化合物在动物模型中降低了血压,但没有一个具有足够的活性与副作用之间的治疗比例,值得进行临床试验。