We report a silver-catalyzed hydroalkoxylation of C2-alkynyl quinazolinones to prepare a series of novel quinazolinone-fused eight-membered N,O-heterocycles in good-to-excellent yields through a selective 8-endo-dig cyclization. Mechanistic studies revealed that the silver catalyst might aid bidentate coordination of an imine group and alkyne to facilitate 8-endo-dig cyclization to afford eight-membered N,O-heterocycles. Also, the proposed bimetal silver intermediates might promote hydroalkoxylation rapidly for quinazolinones bearing terminal alkynes at the C2-position. Biological evaluations revealed that most of the designed quinazolinone-fused eight-membered N,O-heterocycles inhibited nitric-oxide generation significantly in lipopolysaccharide-stimulated RAW264.7 cells and displayed their bioactivity as potentially good anti-inflammatory agents.

中文翻译：

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银（I）催化的C2-炔基喹唑啉酮的选择性加氢烷氧基化反应合成喹唑啉酮稠合的八元N，O-杂环

我们报告了银催化的C2-炔基喹唑啉酮的加氢烷氧基化反应，通过选择性的8-内-地-环化制备了一系列新颖的喹唑啉酮稠合的八元N，O-杂环，并具有良好至优异的产率。机理研究表明，银催化剂可能有助于亚胺基和炔烃的双齿配位，以促进8-内挖环化得到八元N，O-杂环。同样，对于在C 2位带有末端炔烃的喹唑啉酮，建议的双金属银中间体可能会迅速促进加氢烷氧基化。生物学评估表明，大多数设计的喹唑啉酮融合的八元N，O-杂环在脂多糖刺激的RAW264.7细胞中均能显着抑制一氧化氮的产生，并显示出其作为潜在的良好抗炎剂的生物活性。