Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.
Department of Medicinal and Applied Chemistry, Kaohsiung Medical University , 100, Shih-Chuan first Road, Kaohsiung 807-08, Taiwan.
Org Lett. 2017 May 5;19(9):2370-2373. doi: 10.1021/acs.orglett.7b00907. Epub 2017 Apr 14.
An efficient and regioselective synthesis of novel 1,2,3-triazole-fused-1,5-benzoxazocinones through intramolecular cyclization of substituted ethynyl triazoyl benzoic acids was explored. A crucial precursor 5-iodo-1,2,3-triazole benzoate was obtained from substituted 2-azido benzoic acid esters in a single step through a Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC) reaction using a CuI/NBS catalytic system. A carbon-carbon triple bond was installed through a Sonogashira coupling reaction by various terminal alkynes. Finally, the 1,4,5-substituted ethynyl triazoyl benzoic acids were cyclized by a AgOTf-mediated intramolecular cyclization to afford 8-endo-dig 1,2,3-triazole-fused-1,5-benzoxazocinones exclusively.
通过取代的乙炔基三唑苯甲酸的分子内环化反应，探索了一种新型 1,2,3-三唑并-1,5-苯并恶嗪酮的高效和区域选择性合成方法。通过使用 CuI/NBS 催化体系的铜催化叠氮化物-炔烃环加成（CuAAC）反应，可从取代的 2-叠氮苯甲酸酯一步得到关键前体 5-碘-1,2,3-三唑苯甲酸酯。通过各种末端炔烃的 Sonogashira 偶联反应安装了一个碳-碳三键。最后，通过 AgOTf 介导的分子内环化反应，将 1,4,5-取代的乙炔基三唑苯甲酸环化，仅得到 8-endo-dig 1,2,3-三唑并-1,5-苯并恶嗪酮。
