Liu Xiao-Hui, Yu Hai-Yang, Huang Jia-Ying, Su Ji-Hu, Xue Can, Zhou Xian-Tai, He Yao-Rong, He Qian, Xu De-Jing, Xiong Chao, Ji Hong-Bing
Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University Zhuhai 519082 China
CAS Key Laboratory of Microscale Magnetic Resonance, University of Science and Technology of China Hefei 230026 China
Chem Sci. 2022 Jul 28;13(33):9560-9568. doi: 10.1039/d2sc02606f. eCollection 2022 Aug 24.
Developing highly efficient catalytic protocols for C-sp(3)-H bond aerobic oxidation under mild conditions is a long-desired goal of chemists. Inspired by nature, a biomimetic approach for the aerobic oxidation of C-sp(3)-H by galactose oxidase model compound CuL and NHPI (-hydroxyphthalimide) was developed. The CuL-NHPI system exhibited excellent performance in the oxidation of C-sp(3)-H bonds to ketones, especially for light alkanes. The biomimetic catalytic protocol had a broad substrate scope. Mechanistic studies revealed that the Cu-radical intermediate species generated from the intramolecular redox process of CuLH was critical for O activation. Kinetic experiments showed that the activation of NHPI was the rate-determining step. Furthermore, activation of NHPI in the CuL-NHPI system was demonstrated by time-resolved EPR results. The persistent PINO (phthalimide--oxyl) radical mechanism for the aerobic oxidation of C-sp(3)-H bond was demonstrated.
在温和条件下开发用于C-sp(3)-H键有氧氧化的高效催化方案是化学家们长期以来期望实现的目标。受自然启发，开发了一种由半乳糖氧化酶模型化合物CuL和NHPI（N-羟基邻苯二甲酰亚胺）对C-sp(3)-H进行有氧氧化的仿生方法。CuL-NHPI体系在将C-sp(3)-H键氧化为酮方面表现出优异性能，尤其是对于轻质烷烃。该仿生催化方案具有广泛的底物范围。机理研究表明，由CuLH的分子内氧化还原过程产生的Cu-自由基中间体物种对于O活化至关重要。动力学实验表明，NHPI的活化是速率决定步骤。此外，时间分辨电子顺磁共振结果证明了CuL-NHPI体系中NHPI的活化。证明了C-sp(3)-H键有氧氧化的持久PINO（邻苯二甲酰亚胺-N-氧基）自由基机理。
