Cp<sub>2</sub>TiCl-Promoted <i>Endo-Trig</i> Radical Cyclization to Six- and Seven-Membered Carbocycles: Synthesis of (±)-Isoclavukerin A
作者:Sabnam Begum、Rajarshi Bhattacharya、Shashwati Paul、Tushar Kanti Chakraborty
DOI:10.1021/acs.joc.3c01356
日期:2023.9.1
investigate the less explored endo-trig radical cyclization in activated olefin-appended epoxides using Cp2TiCl. The radical generated by the Ti(III)-promoted reductive opening of the epoxy ring promptly underwent endo-trig cyclization, giving access to differently 1,3-disubstituted six- and seven-membered carbocycles in good yields and diastereoselectivity. This protocol was successfully employed
进行了一项系统研究,以研究使用 Cp 2 TiCl在活化的烯烃附加环氧化物中探索较少的内触发自由基环化。Ti(III) 促进的环氧环还原开环产生的自由基迅速进行内三环化,以良好的产率和非对映选择性获得不同的 1,3-二取代六元和七元碳环。该方案已成功用于构建 5,7- 和 6,7- 融合双环框架,需要从头合成属于三正愈创木烷类倍半萜烯天然产物的 (±)-isoclavukerin A,只需八个简单步骤即可市售起始材料。除了 Ti(III) 介导的反应作为合成中的关键步骤外,烯丙基次磺酸盐中间体的连续[2,3]-同向重排/顺式消除成功地在氢化甘菊环核心中形成了高度受限的二烯部分。目标分子。