| 配分額 *注記 |
7,800千円 (直接経費: 6,000千円、間接経費: 1,800千円)
2021年度: 3,900千円 (直接経費: 3,000千円、間接経費: 900千円)
2020年度: 3,900千円 (直接経費: 3,000千円、間接経費: 900千円)
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| 研究開始時の研究の概要 |
Transition-metal-catalyzed C-H bond activation is of much interest, but simple arenes are difficult substrates. I plan a hybrid strategy for the C-H functionalization of simple arenes: catalytic activation of an arene substrate by pi-coordination, which decrease the electron density and enables smooth and selective transition-metal-catalyzed functionalization.
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| 研究実績の概要 |
The purpose of this research is the development of a hybrid strategy for C-H functionalization of simple arenes: activation of an arene substrate by catalytic pi-coordination to a metal such as Cr, causing a strong decrease in electron density on the arene, and thus increasing the reactivity towards nucleophilic attack of a reagent or electron-rich metal catalyst.
During FY2021, we found that this strategy can be used for the borylation of simple arenes such as toluene, xylene, etc. with bis(pinacolato)diboron in the presence of a base, without the requirement of a transition metal catalyst. The arene is activated by transient ligand exchange with a chromium naphthalene complex, and the reaction does not proceed at all without this activation. While the ligand exchange proceeded smoothly, at the moment the reaction is not catalytic with regard to the chromium complex. Mechanistic studies through experiment and calculation revealed that the reaction proceeds through nucleophilic attack of a borate species.
We also found that a similar strategy can be used for the activation of aryl chlorides, resulting in reaction with an arene such as benzene through a radical mechanism. Thus, a aryl chloride coordinated to chromium carbonyl reacted with a solvent amount of arene in the presence of an alcoxide and a bipyridine ligand to produce the biaryl coupling product.
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