Department of Chemistry, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Frontiers Science Center for Synthetic Biology (Ministry of Education), and Tianjin Collaborative Innovation Centre of Chemical Science & Engineering, Tianjin University, Tianjin 300072, P.R. China.
Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, P.R. China.
Org Lett. 2020 Oct 2;22(19):7762-7767. doi: 10.1021/acs.orglett.0c03025. Epub 2020 Sep 23.
Cyano-tetrazole is the first reported compound that bears four nitrogen atoms in a single five-membered ring. This unique molecular scaffold has long been ignored after its discovery in 1885, mainly attributed to the scarcity of available synthetic methods. Indeed, the most popular approach to tetrazoles (that is the cycloaddition reaction between nitriles and azides) has inevitably excluded the possibility of introducing valuable cyano groups to decorate the final heterocyclic cores. Here, we describe a completely different disconnection strategy to the long time-pursued cyano-tetrazoles via a simple, direct, and practical cycloaddition transformation between readily accessible aryl diazonium salts and diazoacetonitrile. This method provides both regioisomers of disubstituted tetrazoles from the same set of starting materials in a metal cation controlled fashion.
氰基四唑是第一个被报道的在单个五元环中含有四个氮原子的化合物。自 1885 年发现以来，这种独特的分子支架长期以来一直被忽视，主要是由于缺乏可用的合成方法。事实上，最流行的四唑合成方法（即腈和叠氮化物之间的环加成反应）不可避免地排除了在最终杂环核中引入有价值的氰基的可能性。在这里，我们通过一种简单、直接和实用的环加成转化，描述了一种与长期以来一直追求的氰基四唑完全不同的断键策略，这种转化是在易得的芳基重氮盐和重氮乙腈之间进行的。该方法以金属阳离子控制的方式，从同一组起始原料中得到两种区域异构体的二取代四唑。
