中国科学院理化技术研究所吴骊珠团队报道了饱和环酮的无胺、无定向基团和氧化还原中性α-烷基化反应。相关研究成果发表在2023年5月23日出版的国际学术期刊《德国应用化学》。

胺催化在化学合成中对羰基化合物的CH键功能化具有强大的作用。对于酮的α-CH键活化，还需要引导基团来引导反应选择性。

该文报道了在没有胺催化剂和指导基团的情况下，环状酮的第一次α-烷基化。¹H NMR、XPS、EPR研究和DFT计算表明，通过直接和选择性活化螯合在胶体量子点（QDs）催化剂表面的酮的惰性α-C–H键，形成α-碳自由基中间体，这对于削弱C–H键至关重要。例如，使用CdSe量子点作为唯一光催化剂的活化平台在可见光照射下进行环酮与烯烃的α-CH烷基化。在没有胺催化剂和导向基团的情况下，氧化还原中性条件下的高阶和原子经济性转化为羰基化学中酮的α-CH官能化开辟了一条新途径。

附：英文原文

Title: Amine-Free, Directing-Group-Free and Redox-Neutral α-Alkylation of Saturated Cyclic Ketones

Author: Jia Qiao, Rui-Nan Ci, Qi-Chao Gan, Cheng Huang, Zan Liu, Hui-Lan Hu, Chen Ye, Bin Chen, Chen-Ho Tung, Li-Zhu Wu

Issue&Volume: 2023-05-23

Abstract: Amine catalysis is powerful for CH bond functionalization of carbonyl compounds in chemical synthesis. For an α-CH bond activation of ketone, directing groups are also required to guide the reaction selectivity. Represented herein is the first α-alkylation of cyclic ketones in the absence of amine catalyst and directing group.1H NMR, XPS, EPR studies and DFT calculation indicate that an α-carbon radical intermediate is formed through direct and selective activation of inert α-C–H bond of ketones chelating on the surface of colloidal quantum dots (QDs) catalyst, which is essential to weaken the C–H bond. As examplified, the activation platform using CdSe QDs as sole photocatalyst executes α-CH alkylation of cyclic ketones with alkenes under visible light irradiation. Without amine catalyst and directing group, the high step- and atom-economy transformation under redox-neutral condition opens a new way for α-CH functionalization of ketone in carbonyl chemistry.

DOI: 10.1002/anie.202305679

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202305679