Yu Lemao, Huang Senhao, Cai Tao, Du Kui, Wu Chunlei, Dong Huaping, Shen Runpu
School of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing312000, China.
Zhejiang Engineering Research Center of Fat-Soluble Vitamin, Shaoxing312000, China.
J Org Chem. 2022 Nov 18;87(22):15114-15119. doi: 10.1021/acs.joc.2c01593. Epub 2022 Oct 6.
Establishing three-dimensional chemicals by using the C-C π bond of indoles has always been a research hotspot in organic synthesis; however, employing the oxidative C-C π bond of indoles to generate imine which would lead to the N-C π bond cyclization under metal-free conditions is still rare. Here, we report a bio-inspired synthesis of triazolo[1,2-]indolines by the oxidative cyclization between -indoles and azomethine imines with 3,3-dimethyldioxirane as the sole oxidant under metal-free and mild conditions. This finding represents an elegant instance of tri-functionalization of -indoles, which provides rapid access to a broad range of triazolo[1,2-]indolines with tetrahydroisoquinolines in one single step. Up to 86% yield and above 20:1 dr value are observed. The radical mechanism and proton migration process have been speculated.
利用吲哚的C-C π键构建三维化合物一直是有机合成领域的研究热点；然而，在无金属条件下利用吲哚的氧化C-C π键生成亚胺并导致N-C π键环化的情况仍然很少见。在此，我们报道了一种受生物启发的合成方法，即在无金属和温和条件下，以3,3-二甲基二氧杂环丙烷作为唯一氧化剂，通过吲哚与甲亚胺亚胺之间的氧化环化反应合成三唑并[1,2-a]吲哚啉。这一发现代表了吲哚三官能化的一个精妙实例，能够一步快速合成一系列带有四氢异喹啉的三唑并[1,2-a]吲哚啉。产率高达86%，非对映选择性（dr）值大于20:1。我们推测了自由基机理和质子迁移过程。
