Wang Hongwei, Kumar Rapolu Kiran, Yu Yang, Zhang Lin, Liu Zhaohong, Liao Peiqiu, Bi Xihe
Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of Chemistry, Northeast Normal University, Renmin Str. 5268#, Changchun, 130024, China.
State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China.
Chem Asian J. 2016 Oct 20;11(20):2841-2845. doi: 10.1002/asia.201601024. Epub 2016 Aug 19.
Imidazole ring is an important five-membered aromatic heterocycle that is widely present in natural products and synthetic molecules. The isocyanide-isocyanide [3+2] cross-cycloaddition reaction constitutes a straightforward method to access imidazoles starting from the easily available chemicals. So far, only three successive reports are known and all lead to the formation of 1,4-disubstituted imidazoles. Here, we report the first isocyanide-isocyanide [3+2] cross-cycloaddition reaction allowing for the formation of 1,4,5-trisubstituted imidazoles under silver catalysis. An unexpected 1,2-migration of sulfonyl, alkoxycaybonyl, and carbamoyl groups took place during the cyclization process that is responsible for the formation of trisubstituted imidazoles. This report displayed a mechanistically novel synthetic method toward a variety of imidazole derivatives, which are otherwise difficult to access by conventional methods.
咪唑环是一种重要的五元芳香杂环，广泛存在于天然产物和合成分子中。异腈-异腈[3+2]交叉环加成反应是一种从易得化学品出发制备咪唑的直接方法。到目前为止，已知仅有三篇连续报道，且均生成1,4-二取代咪唑。在此，我们报道了首例在银催化下通过异腈-异腈[3+2]交叉环加成反应生成1,4,5-三取代咪唑的反应。在环化过程中发生了意外的磺酰基、烷氧羰基和氨基甲酰基的1,2-迁移，这是生成三取代咪唑的原因。本报道展示了一种机理新颖的合成多种咪唑衍生物的方法，而这些衍生物用传统方法难以制备。
