Catalytic Alkene Carboaminations Enabled by Oxidative Proton-Coupled Electron Transfer.
Catalytic Alkene Carboaminations Enabled by Oxidative Proton-Coupled Electron Transfer.
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DOI：
10.1021/jacs.5b05377
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发表时间：
2015-07-29
影响因子：
15
通讯作者：
Knowles RR
中科院分区：
文献类型：
--
作者：
Choi GJ;Knowles RR
在这里，我们描述了一种由铱光催化剂和弱磷酸盐碱组成的双催化剂系统，该系统能够通过协同质子耦合电子转移（PCET）选择性均裂N-芳基酰胺的N-H键（键解离自由能〜100 kcal/mol），并介导所得酰胺自由基的有效碳胺化反应。这种 PCET 活化方式在许多生物氧化还原过程中找到了基础，能够在较弱的烯丙基 C-H 键存在的情况下实现较强的酰胺 N-H 键的形式均裂，这种选择性在传统分子 H 原子受体中并不常见。此外，这种转化可以从简单的酰胺起始材料获得各种结构复杂的杂环。描述了 PCET 工艺的设计、合成范围和机理评估。
Here we describe a dual catalyst system comprised of an iridium photocatalyst and weak phosphate base that is capable of both selectively homolyzing the N–H bonds of N-arylamides (bond dissociation free energies ~ 100 kcal/mol) via concerted proton-coupled electron transfer (PCET) and mediating efficient carboamination reactions of the resulting amidyl radicals. This manner of PCET activation, which finds its basis in numerous biological redox processes, enables the formal homolysis of a stronger amide N–H bond in the presence of weaker allylic C–H bonds, a selectivity that is uncommon in conventional molecular H atom acceptors. Moreover, this transformation affords access to a broad range of structurally complex heterocycles from simple amide starting materials. The design, synthetic scope, and mechanistic evaluation of the PCET process are described.