Primary aliphatic amines are important building blocks in organic synthesis due to the presence of a synthetically versatile NH₂ group. N-functionalization of primary amines is well established, but selective C-functionalization of unprotected primary amines remains challenging. Here, we report the use of CO₂ as an activator for the direct transformation of abundant primary aliphatic amines into valuable γ-lactams under photoredox and hydrogen atom transfer (HAT) catalysis. Experimental and computational studies suggest that CO₂ not only inhibits undesired N-alkylation of primary amines, but also promotes selective intermolecular HAT by an electrostatically accelerated interaction between the in situ-generated negatively charged carbamate and the positively charged quinuclidinium radical. This electrostatic attraction overwhelms the inherent bond dissociation energies which suggest that HAT should occur unselectively. We anticipate that our findings will open up new avenues for amine functionalizations as well as selectivity control in HAT reactions.

由于存在合成通用的 NH ₂基团，脂肪族伯胺是有机合成中的重要组成部分。伯胺的N官能化已经很成熟，但未受保护的伯胺的选择性C官能化仍然具有挑战性。在这里，我们报道了使用CO ₂作为活化剂，在光氧化还原和氢原子转移（HAT）催化下将丰富的脂肪伯胺直接转化为有价值的γ-内酰胺。实验和计算研究表明，CO ₂不仅抑制不需要的伯胺的N-烷基化，而且还通过原位产生的带负电的氨基甲酸酯和带正电的奎宁环自由基之间的静电加速相互作用促进选择性分子间HAT。这种静电吸引力压倒了固有的键解离能，这表明 HAT 应该无选择性地发生。我们预计我们的研究结果将为胺官能化以及 HAT 反应的选择性控制开辟新途径。