通过亲和性调控可转换的自由基羰基化,Journal of the American Chemical Society

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通过亲和性调控可转换的自由基羰基化
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2022-08-08 , DOI: 10.1021/jacs.2c06677
Bin Lu ₁ , Minghao Xu ₂ , Xiaotian Qi ₂ , Min Jiang ₃ , Wen-Jing Xiao _{1,

4} , Jia-Rong Chen _{1,

5}

Affiliation

涉及作为容易获得的 C1 合成子的 CO 的羰基化反应已成为从原料化学品构建羰基化合物的最重要工具之一。尽管有许多通过离子或自由基途径进行羰基化反应的催化方法，但这些方法的一个固有限制是需要控制从相同和简单的起始材料中可转换的单羰基化和双羰基化形成增值产品。在这里，我们描述了一种新策略，该策略利用光氧化还原催化来调节胺偶联配偶体的亲水性，从而驱动可切换的自由基羰基化反应。在双羰基化中，胺首先通过单电子转移氧化转化为氮自由基阳离子并与CO偶联形成氨基甲酰基自由基，其进一步与起始的氰基烷基酰基自由基进行自由基交叉偶联以提供双羰基化产物。在添加化学计量的 4-二甲氨基吡啶 (DMAP) 后，DMAP 竞争性地捕获最初形成的氰基烷基酰基自由基以形成相对稳定的氰基烷基酰基-DMAP 盐，该盐参与随后的亲核胺取代以产生单一羰基化产物。在室温下，在各种胺类亲核试剂存在下，反应以优异的选择性顺利进行，以通用和可控的方式生成有价值的酰胺和 α-酮酰胺。结合实验和计算研究提供了对可能途径的机制见解。

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Switchable Radical Carbonylation by Philicity Regulation

Carbonylation reactions involving CO as readily available C1 synthons have become one of the most important tools for the construction of carbonyl compounds from feedstock chemicals. Despite numerous catalytic methods for carbonylation reactions proceeding via ionic or radical pathways, an inherent limitation to these methods is the need to control switchable single and double carbonylative formation of value-added products from the same and simple starting materials. Here, we describe a new strategy that exploits photoredox catalysis to regulate the philicity of amine coupling partners to drive switchable radical carbonylation reactions. In double carbonylation, amines were first transformed into nitrogen radical cations by single-electron transfer-oxidation and coupled with CO to form carbamoyl radicals, which further underwent radical cross-coupling with the incipient cyanoalkyl acyl radicals to afford the double carbonylation products. Upon the addition of stoichiometric 4-dimethylaminopyridine (DMAP), DMAP competitively traps the initially formed cyanoalkyl acyl radical to form the relatively stabilized cyanoalkyl acyl-DMAP salts that engaged in the subsequent substitution with the nucleophilic amines to produce the single carbonylation products. The reaction proceeded smoothly with excellent selectivity in the presence of various amine nucleophiles at room temperature, generating valuable amides and α-ketoamides in a versatile and controlled fashion. Combined experimental and computational studies provided mechanistic insights into the possible pathways.

更新日期：2022-08-08

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