Light-mediated aerobic oxidation of C(sp 3 )–H bonds by a Ce( iv ) hexachloride complex
Light-mediated aerobic oxidation of C(sp 3 )–H bonds by a Ce( iv ) hexachloride complex
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六氯化物配合物光介导的 C(sp 3 )–H 键有氧氧化
DOI：
10.1039/d2qo00362g
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发表时间：
2022
影响因子：
5.4
通讯作者：
Schelter, Eric J.
中科院分区：
文献类型：
--
作者：
Wang, Yu-Heng;Yang, Qiaomu;Walsh, Patrick J.;Schelter, Eric J.
描述了在温和条件（1 atm，25 °C）下由[NEt 4]2[CeIVCl 6]催化的烷烃和芳烃底物的光化学C（sp 3）-H氧化。时程研究表明，烃类被氧化，在一个逐步的方式，以提供醇，醛，酮和羧酸。通过紫外-可见光谱法观察到催化剂静止状态[CeIVCl 6]2−。开/关光开关实验，量子产率测量，以及平行的C-H/C-D功能化的动力学同位素效应的情况下，建议[NEt 4]2[CeIVCl 6]的配体到金属的电荷转移，以产生Cl stecis的转换限制步骤。在黑光照射下，高度还原的激发态[NEt 4]3[CeIIICl 6]* 物种以及光激发的醛的参与似乎有助于伯醇和醛向羧酸的转化。值得注意的是，发现这种方法能够直接活化轻质烷烃，包括甲烷和乙烷。
A photochemical C(sp3)–H oxygenation of alkane and arene substrates catalyzed by [NEt4]2[CeIVCl6] under mild conditions (1 atm, 25 °C) is described. Time-course studies reveal that the hydrocarbons are oxidized in a stepwise fashion to afford alcohols, aldehydes, ketones, and carboxylic acids. The catalyst resting state, [CeIVCl6]2−, is observed by UV-visible spectroscopy. On/off light-switching experiments, quantum yield measurements, and the absence of a kinetic isotope effect on parallel C–H/C–D functionalization suggest that ligand-to-metal charge transfer of [NEt4]2[CeIVCl6] to generate Cl˙ is the turnover-limiting step. The involvement of a highly reducing excited-state [NEt4]3[CeIIICl6]* species as well as photo-excited aldehyde, under black light irradiation appears to facilitate the conversion of primary alcohols and aldehydes to carboxylic acids. Remarkably, this approach is found to be capable of direct activation of light alkanes, including methane and ethane.