Tamaki Sota, Kuwata Riina, Wakita Shuto, Osakada Yasuko, Fujitsuka Mamoru, Kusamoto Tetsuro, Mashima Kazushi, Tsurugi Hayato
Department of Chemistry, Graduate School of Engineering Science, The University of Osaka, Toyonaka, Osaka, Japan.
Department of Applied Chemistry, Graduate School of Engineering, The University of Osaka, Suita, Osaka, Japan.
Angew Chem Int Ed Engl. 2025 Aug 11;64(33):e202505639. doi: 10.1002/anie.202505639. Epub 2025 Jun 18.
Decarboxylative hydrazination of carboxylic acids was achieved using a 1:5:2 ratio of three metal salts, Ce(OBu), Zr(OBu), and Mn(OAc), as a catalyst under visible light irradiation. The catalytic activity, compared with our previously developed Ce cluster photo-catalysts, was enhanced by the formation of single cerium-incorporated hexanuclear mixed-metal clusters containing a [CeZrO(OH)] core. The manganese salts further accelerated the overall reaction rate (10 times faster reaction rate with the manganese salt than that of the manganese-free conditions). Using the isolated cluster, CeZrO(OH)(OCOCH Bu)(HOCOCH Bu) (4a), with Mn(OAc), phenol and thiophenol-containing carboxylic acids were transformed to their decarboxylative hydrazinated products in moderate to high yields, while a mixture of CeO(OH)(OCOCH Bu)(HOCOCH Bu) (4c) and Mn(OAc) or Ce(OBu), Zr(OBu), and Mn(OAc) yielded lower amounts of the products. These findings highlight the importance of incorporating cerium(IV) into the zirconium-based core to tolerate these easily oxidizable functional groups. Upon exposure of 4a to blue LED light under an argon atmosphere, the CeZr cluster produced 2,2,5,5-tetramethylhexane, a radical coupling product derived from the carboxylate ligand on 4a, in half an equivalent per cluster, consistent with the photo-reduction of cerium(IV) and inertness of the oxo- and hydroxo-bridged Zr motif as a metallo-ligand around the cerium(IV) site. Moreover, decarboxylative oxygenation of carboxylic acids under air followed by treatment with NaBH resulted in the production of one-carbon shortened alcohols in excellent yields when using Ce(OBu) and Zr(OBu) or Hf(OBu) in a 1:5 ratio: the reaction rates were 8-10 times higher than that of the previously developed cerium-catalyzed reaction under identical conditions.
在可见光照射下，使用三种金属盐Ce(OBu)、Zr(OBu)和Mn(OAc)以1:5:2的比例作为催化剂，实现了羧酸的脱羧肼化反应。与我们之前开发的铈簇光催化剂相比，通过形成含有[CeZrO(OH)]核心的单铈掺入六核混合金属簇，催化活性得到了提高。锰盐进一步加快了整体反应速率（有锰盐时的反应速率比无锰条件下快10倍）。使用分离出的簇CeZrO(OH)(OCOCH Bu)(HOCOCH Bu) (4a)与Mn(OAc)，含苯酚和硫酚的羧酸以中等至高产率转化为它们的脱羧肼化产物，而CeO(OH)(OCOCH Bu)(HOCOCH Bu) (4c)与Mn(OAc)的混合物或Ce(OBu)、Zr(OBu)和Mn(OAc)产生的产物量较低。这些发现突出了将铈(IV)掺入锆基核心以耐受这些易氧化官能团的重要性。在氩气气氛下将4a暴露于蓝色LED光下时，CeZr簇每簇产生半当量的2,2,5,5-四甲基己烷，这是一种源自4a上羧酸根配体的自由基偶联产物，这与铈(IV)的光还原以及氧桥和羟基桥连的Zr基序作为铈(IV)位点周围的金属配体的惰性一致。此外，在空气中羧酸的脱羧氧化反应，然后用NaBH处理，当使用比例为1:5的Ce(OBu)和Zr(OBu)或Hf(OBu)时，以优异的产率生成了碳链缩短一个的醇：反应速率比之前在相同条件下开发的铈催化反应高8-10倍。
