Acid-Base Initiated Cyclization and Retrocyclization Reactions of Ethyl 2-(3-Acylselenoureido)benzoates, -thiophene-3-carboxylates and the Corresponding 2-(3-Acylisoselenoureido) Derivatives
作者:Jiří Šibor、Dalimil Žůrek、Otakar Humpa、Pavel Pazdera
DOI:10.3390/50100037
日期:——
the same conditions. The reaction of potassium ethoxide on selenazines 13-18 in the ethanol solution evoked retrocyclization to the starting acylselenoureas 1-6. Both types of the title compounds, i.e. selenoureas 1-6 and isoselenoureas 7-12, were deprotonated in a methanol solution of potassium hydroxide used in an equimolar amount, giving rise to potassium salts 19-24, which were isolated only for
据报道,酸和碱引发的硒脲 1-6 和异硒脲 7-12 的环化和逆环化反应生成了稠合的 4H-1,3-硒嗪和 1,2,3,4-四氢嘧啶-4-one 骨架。稠合的 2-acylamino-4H-1,3-selenazine-4-ones 13-18 是通过浓硫酸在室温下对酰基硒脲 1-6 或 2,2-二甲基丙酰基异硒脲 10-12 的作用形成的。另一方面,在相同条件下,在该环缩合反应中未获得苯甲酰基异硒脲 7-9。乙醇溶液中乙醇钾与硒嗪 13-18 的反应引起了对起始酰基硒脲 1-6 的逆环化。两种类型的标题化合物,即硒脲 1-6 和异硒脲 7-12,在等摩尔量的氢氧化钾甲醇溶液中去质子化,产生钾盐 19-24,仅分离出噻吩系列。通过在提供的甲醇溶液中加热分离的钾盐20、21、23和24,形成脱酰和异硒脲26、27。原位制备的盐 19、22 在相同条件下环化并脱酰基为 4-selanyl-3,