A synthetic route to novel 3-substituted-2,1-benzisoxazoles from 5-(2-nitrobenzylidene)(thio)barbiturates
作者:João L. Serrano、Eunice Cavalheiro、Sónia Barroso、Maria J. Romão、Samuel Silvestre、Paulo Almeida
DOI:10.1016/j.crci.2017.10.002
日期:2017.11
Résumé 2,1-Benzisoxazoles, also called anthranils, are one of the two types of aromatic bicyclic heterocycles having a benzene ring fused with an isoxazole, which are particularly recognized as valuable intermediates in organic synthesis. Nevertheless several methods can be found in the literature to prepare 2,1-benzisoxazoles, we herein report a new, efficient, simple, mild, and alternative procedure to prepare 3-substituted-2,1-benzisoxazoles from 5-(2-nitrobenzylidene)barbiturates in moderate to good yields (51–82%). All the novel benzisoxazoles showed spectral data fully consistent with the assigned structures, which were unequivocally confirmed by single crystal X-ray analysis. A possible mechanism of the reaction is proposed. In addition, a screening of the bioactivity of these benzisoxazoles as xanthine oxidase inhibitors, antioxidants, and cytotoxic compounds was performed. The benzisoxazole formed from barbituric acid revealed moderate xanthine oxidase inhibitory effects (IC50 = 22.10 μM). Supplementary Materials: Supplementary materials for this article are supplied as separate files: figs1.jpg figs2.jpg figs3.jpg mmc1.docx
摘要
2,1-苯并异噁唑,亦称为氨基苯甲酸,是两种环状芳香族杂环化合物之一,具有一个与异噁唑融合的苯环,特别被认为是有机合成中宝贵的中间体。尽管文献中存在几种合成2,1-苯并异噁唑的方法,我们在此报道一种新的、高效、简单、温和的替代程序,从5-(2-硝基苄亚基)巴比妥酸酯合成3-取代的2,1-苯并异噁唑,产率中等至良好(51-82%)。所有新合成的苯并异噁唑的光谱数据与分配的结构完全一致,且通过单晶X射线分析得到了明确确认。提出了一种可能的反应机制。此外,还对这些苯并异噁唑作为黄嘌呤氧化酶抑制剂、抗氧化剂和细胞毒性化合物的生物活性进行了筛选。从巴比妥酸形成的苯并异噁唑显示出中等的黄嘌呤氧化酶抑制作用(IC50 = 22.10 μM)。
补充材料:
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figs1.jpg
figs2.jpg
figs3.jpg
mmc1.docx