Photochemical oxidation of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (emorfazone) by pyrimido(5,4-g)pteridine 5-oxide. An attempt to apply a functional chemical model for biological oxidations to drug-metabolism studies.
作者:YOSHIFUMI MAKI、KAORU SHIMADA、MAGOICHI SAKO、YUKIO KITADE、KOSAKU HIROTA
DOI:10.1248/cpb.36.1714
日期:——
Irradiation of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (2) (Emorfazone) with ultraviolet (UV)-visible light in the presence of 1, 3, 7, 9-tetrabutyl-2, 4, 6, 8(1H, 3H, 7H, 9H)-pyrimido-[5, 4-g]pteridinetetrone 5-oxide (1a), followed by chromatography of the reaction mixture, resulted in the isolation of 5-(2, 3-dihydro-1, 4-oxazin-4-yl)-4-ethoxy-2-methyl-3(2H)-pyridazinone (3), 4-ethoxy-5-(2-hydroxyethylamino)-2-methyl-3(2H)-pyridazinone (4), 4-ethoxycarbonyl-2-methyl-4-morpholino-3(2H)-pyrazolone (5), 4, 4'-bi[4-ethoxycarbonyl-2-methyl-3(2H)-pyrazolone] (6) and 1, 3, 7, 9-tetrabutyl-2, 4, 6, 8(1H, 3H, 7H, 9H)-pyrimido[5, 4-g]pteridinetetrone (1b). The product 3 is produced as a result of photochemical dehydrogenation of 2 by 1a. The formation of the morpholine-ring-opening product 4, one of the metabolites of 2, was proved to occur via the autoxidation of 3 and subsequent stepwise ring cleavage in the presence of oxygen and moisture. The formation of the novel ring-contracted product 5 involves oxygen-atom transfer from 1a to 2 in an excited state. The dimer 6 was shown to be a secondary product formed by further photolysis of 5.
对4-乙氧基-2-甲基-5-莫耳啉-3(2H)-吡唑酮(2)(Emorfazone)在1, 3, 7, 9-四正丁基-2, 4, 6, 8(1H, 3H, 7H, 9H)-嘧啶[5, 4-g]嘌呤四酮5-氧化物(1a)存在下进行紫外(UV)可见光照射,随后对反应混合物进行色谱分离,得到了5-(2, 3-二氢-1, 4-噁唑啉-4-基)-4-乙氧基-2-甲基-3(2H)-吡唑酮(3)、4-乙氧基-5-(2-羟基乙氨基)-2-甲基-3(2H)-吡唑酮(4)、4-乙氧基羰基-2-甲基-4-莫耳啉-3(2H)-吡唑酮(5)、4, 4'-双[4-乙氧基羰基-2-甲基-3(2H)-吡唑酮](6)及1, 3, 7, 9-四正丁基-2, 4, 6, 8(1H, 3H, 7H, 9H)-嘧啶[5, 4-g]嘌呤四酮(1b)。产物3是通过1a对2进行光化学脱氢反应产生的。形成产物4,即2的代谢物之一的莫耳啉环开环产物,被证明是在氧气和水分的存在下,通过3的自氧化以及后续的逐步开环反应形成的。新型的环缩产物5的形成涉及了在激发状态下,氧原子从1a转移到2。二聚体6被证明是通过进一步光解5而形成的次级产物。