Division of Pharmaceutical Sciences, Graduate School of Medical Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
J Am Chem Soc. 2022 May 11;144(18):7953-7959. doi: 10.1021/jacs.2c00527. Epub 2022 Apr 27.
We demonstrate Markovnikov hydroalkoxylation of unactivated alkenes using alcohols through a triple catalysis consisting of photoredox, cobalt, and Brønsted acid catalysts under visible light irradiation. The triple catalysis realizes three key elementary steps in a single catalytic cycle: (1) Co(III) hydride generation by photochemical reduction of Co(II) followed by protonation, (2) metal hydride hydrogen atom transfer (MHAT) of alkenes by Co(III) hydride, and (3) oxidation of the alkyl Co(III) complex to alkyl Co(IV). The precise control of protons and electrons by the three catalysts allows the elimination of strong acids and external reductants/oxidants that are required in the conventional methods.
我们展示了通过光氧化还原、钴和布朗斯台德酸三重催化体系，在可见光照射下，醇对未活化烯烃的 Markovnikov 羟烷化反应。三重催化体系在单个催化循环中实现了三个关键的基元步骤：（1）Co(II)经光化学还原生成 Co(III)氢化物，随后质子化；（2）Co(III)氢化物对烯烃进行金属氢原子转移（MHAT）；（3）烷基 Co(III)配合物被氧化为烷基 Co(IV)。三个催化剂精确地控制质子和电子，从而消除了传统方法中所需的强酸和外加还原剂/氧化剂。
