光催化的有氧氧化反應是一種新穎且綠色的合成策略。本研究利用氧化亞銅 奈米晶體作為光催化劑，用於苯基硼酸羥基化反應。在控制實驗中可知光源、氧 氣及電子供體對於反應的重要性，並且水為最佳的溶劑，乙基二異丙基胺 (DIPEA)為最佳的電洞受體，在最佳條件下探討催化劑。當用具不同晶面的氧化 亞銅立方體、八面體以及菱形十二面體奈米晶體為催化劑，結果具{110}面的菱 形十二面體氧化亞銅奈米晶體的催化效果為最好，產率可達 95%。我們也將該實 驗條件用於帶不同官能團的芳基硼酸以進行羥基化，發現不同官能團通常都可得 到不錯的產率。最後根據自由基捕捉實驗以及 EPR 實驗提出一個可能的機制。

Photocatalytic aerobic oxidation is a novel and green synthetic strategy. In this study, Cu2O nanocrystals were used as photocatalysts for the hydroxylation of phenylboronic acids. The importance of light source, oxygen and hole acceptor has been established in the control experiments. The catalytic activities of {100}-bound Cu2O cubes, {111}-enclosed octahedra, and {110}-terminated rhombic dodecahedra have been investigated using the best reaction conditions with water as the best solvent and diisopropylethylamine (DIPEA) as the best hole acceptor. Rhombic dodecahedra showed the best catalytic performance with 95% yield. Hydroxylation of aryl boronic acids with different functional groups were also explored, showing good to excellent product yields. A possible mechanism has been proposed based on radical trapping experiments and EPR experiment

1. Shibasaki, S.; Honishi, Y.; Nakagawa, N.; Yamazaki, M.; Mizuno, Y.; Nishida, Y.; Sugimoto, K.; Yamamoto, K. Highly Transparent Cu2O Absorbing Layer for Thin Film Solar Cells. Appl. Phys. Lett. 2021, 119, 242102.
2. Wan, X.; Wang, J.; Zhu, L.; Tang, J. Gas Sensing Properties of Cu2O and Its Particle Size and Morphology-Dependent Gas-Detection Sensitivity. J. Mater. Chem. A 2014, 2, 13641–13647.
3. Chanda, K.; Rej, S.; Huang, M. H. Investigation of Facet Effects on the Catalytic Activity of Cu2O Nanocrystals for Efficient Regioselective Synthesis of 3,5-Disubstituted Isoxazoles. Nanoscale 2013, 5, 12494‒12501.
4. Tsai, H.-Y.; Madasu, M.; Huang, M. H. Polyhedral Cu2O Crystals for Diverse Aryl Alkyne Hydroboration Reactions. Chem.‒Eur. J. 2018, 25, 1300–1303.
5. Madasu, M.; Huang, M. H. Cu2O Polyhedra for Aryl Alkyne Homocoupling Reactions. Catal. Sci. Technol. 2020, 10, 6948–6952.
6. Huang, W.-C.; Lyu, L.-M.; Yang, Y.-C.; Huang, M. H. Synthesis of Cu2O Nanocrystals from Cubic to Rhombic Dodecahedral Structures and Their Comparative Photocatalytic Activity. J. Am. Chem. Soc. 2011, 134, 1261–1267.
7. Tan, C.-S.; Hsu, S.-C.; Ke, W.-H.; Chen, L.-J.; Huang, M. H. Facet-Dependent Electrical Conductivity Properties of Cu2O Crystals. Nano Lett. 2015, 15, 2155–2160.
8. Chu, C.-Y.; Huang, M. H. J. Mater. Chem. A 2017, 5, 15116–15123.
9. Kanazawa, C.; Kamijo, S.; Yamamoto, Y. Synthesis of Imidazoles through the Copper-Catalyzed Cross-Cycloaddition between Two Different Isocyanides. J. Am. Chem. Soc. 2006, 128, 10662–10663.
10. Tsang, A. S.-K.; Kapat, A.; Schoenebeck, F. Factors That Control C–C Cleavage versus C–H Bond Hydroxylation in Copper-Catalyzed Oxidations of Ketones with O2. J. Am. Chem. Soc. 2016, 138, 518–526.
11. Che, F.; Wang, M.; Yu, C.; Sun, X.; Xie, D.; Wang, Z.; Zhang, Y. Cu2O-Catalyzed Selective 1,2-Addition of Acetonitrile to α,β-Unsaturated Aldehydes. Org. Chem. Front. 2020, 7, 868–872.
12. Albuquerque, B. R.; Heleno, S. A.; Oliveira, M. B.; Barros, L.; Ferreira, I. C. Phenolic Compounds: Current Industrial Applications, Limitations and Future Challenges. Food Funct. 2021, 12, 14–29.
13. Zarei, A.; Khazdooz, L.; Aghaei, H.; Gheisari, M. M.; Alizadeh, S.; Golestanifar, L. Synthesis of Phenols by Using Aryldiazonium Silica Sulfate Nanocomposites. Tetrahedron 2017, 73, 6954–6961.
14. Kormos, C. M.; Leadbeater, N. E. Direct Conversion of Aryl Halides to Phenols Using High-Temperature or Near-Critical Water and Microwave Heating. Tetrahedron 2006, 62, 4728–4732.
15. Anderson, K. W.; Ikawa, T.; Tundel, R. E.; Buchwald, S. L. The Selective Reaction of Aryl Halides with KOH:  Synthesis of Phenols, Aromatic Ethers, and Benzofurans. J. Am. Chem. Soc. 2006, 128, 10694–10695.
16. Song, Z.-Q.; Wang, D.-H. Palladium-Catalyzed Hydroxylation of Aryl Halides with Boric Acid. Org. Lett. 2020, 22, 8470–8474.
17. Zou, Y.-Q.; Chen, J.-R.; Liu, X.-P.; Lu, L.-Q.; Davis, R. L.; Jørgensen, K. A.; Xiao, W.-J. Highly Efficient Aerobic Oxidative Hydroxylation of Arylboronic Acids: Photoredox Catalysis Using Visible Light. Angew. Chem., Int. Ed. 2011, 51, 784–788.
18. Pitre, S. P.; McTiernan, C. D.; Ismaili, H.; Scaiano, J. C. Mechanistic Insights and Kinetic Analysis for the Oxidative Hydroxylation of Arylboronic Acids by Visible Light Photoredox Catalysis: A Metal-Free Alternative. J. Am. Chem. Soc. 2013, 135, 13286–13289.
19. Wei, P.-F.; Qi, M.-Z.; Wang, Z.-P.; Ding, S.-Y.; Yu, W.; Liu, Q.; Wang, L.-K.; Wang, H.-Z.; An, W.-K.; Wang, W. Benzoxazole-Linked Ultrastable Covalent Organic Frameworks for Photocatalysis. J. Am. Chem. Soc. 2018, 140, 4623–4631.
20. Yu, X.; Cohen, S. M. Photocatalytic Metal–Organic Frameworks for the Aerobic Oxidation of Arylboronic Acids. Chem. Commun. 2015, 51, 9880–9883.
21. Xu, Z.-Y.; Luo, Y.; Zhang, D.-W.; Wang, H.; Sun, X.-W.; Li, Z.-T. Iridium Complex-Linked Porous Organic Polymers for Recyclable, Broad-Scope Photocatalysis of Organic Transformations. Green Chem. 2020, 22, 136–143.
22. Anito, D. A.; Wang, T.-X.; Liang, H.-P.; Ding, X.; Han, B.-H. Bis(terpyridine) Ru(III) Complex Functionalized Porous Polycarbazole for Visible-Light Driven Chemical Reactions. Polym. Chem. 2021, 12, 4557–4564.
23. Togashi, H.; Shinzawa, H.; Matsuo, T.; Takeda, Y.; Takahashi, T.; Aoyama, M.; Oikawa, K.; Kamada, H. Analysis of Hepatic Oxidative Stress Status by Electron Spin Resonance Spectroscopy and Imaging. Free Radical Biology and Medicine 2000, 28, 846–853.