CCC pincer Ru complex-catalyzed C–H vinylation/6π-E-cyclization of aldimines for constructing 4H-pyrido[1,2-a]pyrimidines,Chemical Science

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CCC pincer Ru complex-catalyzed C–H vinylation/6π-E-cyclization of aldimines for constructing 4H-pyrido[1,2-a]pyrimidines
Chemical Science ( IF 7.6 ) Pub Date : 2024-09-03 , DOI: 10.1039/d4sc05067c
Heng Cai ₁ , Yong-Qiang Tu _{1,

2} , Qiang Niu ₃ , Wen-Ping Xie ₂ , Bin Wang ₁ , Ka Lu ₁ , Zi-Hao Li ₂ , Fu-Min Zhang ₁ , Xiao-Ming Zhang ₁

Affiliation

An unusual cascade C–H activation, vinylation and 6π-electrocyclization of 2-pyridyl aldimines with vinyl bromides/triflates was achieved using catalysis with a unique CCC pincer NHC–Ru(III) complex (Cat B). This reaction was found to enable a rapid and diverse synthesis of polycyclic 4H-pyrido[1,2-a]pyrimidine derivatives in mostly good to high yields, and with a broad substrate scope. A mechanistic study suggested the formation of a semi-opened Ru(III) intermediate chelating/activating the aldimine, and the occurrence of single-electron transfer (SET) to generate a vinyl radical, followed by vinylation and then an intramolecular 6π-electrocyclization of 1N,3N-hexatrene to form the product. This protocol provides a convenient approach for preparing and seeking new drug candidates.

中文翻译：

CCC 钳 Ru 配合物催化的醛二胺的 C-H 乙烯基化/6π-E 环化反应，用于构建 4H-吡啶[1,2-a] 嘧啶

使用独特的 CCC 钳形 NHC-Ru（III）配合物（Cat B）进行催化，实现了 2-吡啶基二胺与乙烯基溴化物/三氟甲磺酸酯的不寻常级联 C-H 活化、乙烯基化和 6π-电环化。发现该反应能够快速、多样地合成多环 4H-吡啶[1,2-a] 嘧啶衍生物，产量大多为高，底物范围广。一项机理研究表明，形成半开放的 Ru（III）中间体螯合/激活阿丁胺，并发生单电子转移（SET）以产生乙烯基自由基，然后是乙烯基化，然后是 1N，3 N-己三烯的分子内 6π 电环化以形成产物。该方案为准备和寻找新的候选药物提供了一种便捷的方法。

更新日期：2024-09-03

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