Relay Palladium/Copper Catalysis Enabled Silylative [5 + 1] Benzannulation Using Terminal Alkynes as One-Carbon Units

Abstract

Using terminal alkyne as a nontraditional one-carbon (C1) unit and silylborane as an external silicon pronucleophile, a relay palladium/copper-catalyzed silylative [5 + 1] benzannulation of 3-acetoxy-1,4-enynes for producing polysubstituted arylsilanes, especially including bioactive motif-based analogues, in a single reaction step through benzene ring skeleton assembly and silyl intermolecular incorporation cascades is developed. Mechanistic studies show that this reaction allows the terminal sp-hybridized carbon atom in terminal alkynes as a C1 unit via cleavage of two π-bonds and one C­(sp)–H bond.

State-of-Art Advances on Silylation-Initiated Annulation Reactions

“…中间体 8 经历第二 次 CO 插入, 依次经历还原消除和异构化, 最终生成产 物 3 并再生活性 Pd(0)物种. 2020 年, 李金恒课题组 [6] 报道了一例 Pd/Cu 共催化 3- 2020 年, 赵东兵等 [7] 报道了一种四元和五元硅烷环 在钯催化下开环再环化, 实现了一种独特的交叉偶联扩 环反应(Scheme 5 2021 年, 徐利文课题组 [11] 报道了钯催化含苯乙烯…”