Several 4-substituted 1,3,5-triazino[1,2-a]benzimidazol-2-amines were prepared via cyclization of 2-benzimidazolylguanidine with various reactants. The prototropic tautomerism in the obtained dihydro analogs was investigated. According to the NMR data, the 3,4-dihydro form was found to predominate in DMSO solutions. All tested compounds inhibited the activity of mammalian dihydrofolate reductase. The most active compound was 4,4-dimethyl-3,4-dihydro[1,3,5]triazino[1,2-a]benzimidazol-2-amine (IC50 = 10.9 mM).

中文翻译：

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1,3,5-triazino[1,2-a]benzimidazol-2-amines的合成及生物活性

几个 4-取代 1,3,5-triazino[1,2-a]benzimidazol-2-amines 通过 2-benzimidazolylguanidine 与各种反应物的环化反应制备。研究了所得二氢类似物的质子互变异构现象。根据 NMR 数据，发现 3,4-二氢形式在 DMSO 溶液中占主导地位。所有测试的化合物均抑制哺乳动物二氢叶酸还原酶的活性。活性最强的化合物是 4,4-二甲基-3,4-二氢[1,3,5]三嗪基[1,2-a]苯并咪唑-2-胺（IC50 = 10.9 mM）。