Direct Access to Bridged Polycyclic Skeletons by Merging Oxidative C-H Annulation and Cascade [4+2] Cycloaddition
Direct Access to Bridged Polycyclic Skeletons by Merging Oxidative C-H Annulation and Cascade [4+2] Cycloaddition
复制标题
通过合并氧化 C-H 成环和级联直接获得桥连多环骨架 [4 2] 环加成
DOI：
10.1021/acs.orglett.1c03652
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发表时间：
2021-12-21
期刊：
影响因子：
5.2
通讯作者：
Liu, Pei-Nian
中科院分区：
文献类型：
--
作者：
He, Yan;Wang, Heng;Liu, Pei-Nian
我们报道了一种分步经济的策略，通过合并氧化C-H成环和级联环加成直接合成桥连多环骨架。在该方案中，首先通过氧化C-H环化反应合成了螺[环戊烷-1，3 '-二氢吲哚]-2，4-二烯-2'-酮。随后与亲双烯体进行级联[4 + 2]环加成反应，得到桥联的双环[2.2.1]喹啉-2（1H）-酮，并实现了两个季碳中心和三个C-C键的一锅构建。后者的机理研究表明，级联开环，1，5-σ迁移重排，[4 + 2]环加成过程。
We report a step-economic strategy for the direct synthesis of bridged polycyclic skeletons by merging oxidative C-H annulation and cascade cycloaddition. In the protocol, spiro[cyclopentane-1,3'-indoline]-2,4-dien-2'-ones were first synthesized by oxidative C-H annulation of ethylideneoxindoles with alkynes. Subsequent cascade [4 + 2] cycloaddition with dienophiles gave the bridged bicyclo[2.2.1]quinolin-2(1H)-ones and enabled the one-pot construction of two quaternary carbon centers and three C-C bonds. Mechanistic investigations of the latter suggest a cascade ring-opening, 1,5-sigmatropic rearrangement, and [4 + 2] cycloaddition process.