Transition Metal-Free Supramolecular Photoredox Catalysis in Water: A Phenoxazine Photocatalyst Encapsulated in V-Shaped Aromatic Amphiphiles
Transition Metal-Free Supramolecular Photoredox Catalysis in Water: A Phenoxazine Photocatalyst Encapsulated in V-Shaped Aromatic Amphiphiles
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DOI：
10.1021/acscatal.0c04221
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发表时间：
2020-12-04
期刊：
影响因子：
12.9
通讯作者：
Akita, Munetaka
中科院分区：
文献类型：
--
作者：
Noto, Naoki;Hyodo, Yuki;Akita, Munetaka
在水中利用可见光作为唯一能源进行有机反应是现代合成有机化学的目标之一，而用水溶性分子胶囊封装光氧化还原催化剂是一种很有前景的策略。在此，我们报道了一种由V形芳香两亲物和吩恶嗪光氧化还原催化剂组成的无过渡金属超分子催化剂。一种纳米尺寸的分子胶囊能够在水中高效摄取有机光氧化还原催化剂，并且可以通过选择主客体组合来调节超分子催化作用。该体系能够在可见光照射下有效还原有机分子，并产生各种以碳为中心的自由基，如羰自由基、芳基自由基和三氟甲基自由基，用于水中的有机反应。特别是，与有机溶剂中的光氧化还原催化相比，目前的超分子催化对频哪醇偶联反应更为有效，而且它还能够实现催化剂的循环利用和底物选择性反应，这些是有机溶剂中传统的光氧化还原催化难以实现的。
An organic reaction in water using visible light as the only energy source is one of the goals of modern synthetic organic chemistry, and the encapsulation of a photoredox catalyst by a water-soluble molecular capsule is a promising strategy for it. Herein, we report on a transition metal-free supramolecular catalyst composed of V-shaped aromatic amphiphiles and a phenoxazine photoredox catalyst. A nanosized molecular capsule can efficiently uptake an organic photoredox catalyst in water, and the supramolecular catalysis can be tuned by choice of the host-guest combination. This system allows for the effective reduction of organic molecules under visible light irradiation and generates various carbon-centered radicals, such as ketyl radicals, aryl radicals, and trifluoromethyl radicals, for organic reactions in water. In particular, the present supramolecular catalysis turns out to be effective for pinacol couplings compared to the photoredox catalysis in organic solvents, and furthermore, it enables recycling of the catalyst and substrate-selective reactions, which are difficult to be achieved by the conventional photoredox catalysis in organic solvents.