Development of Functionalization Reactions of p-Benzyne toward Application in Organic Synthesis

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14617
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 33020:Synthetic organic chemistry-related
• Research Institution: Kyoto University (2022); Kwansei Gakuin University (2021)
• Principal Investigator: Nakatsuka Soichiro 京都大学, 理学研究科, 特定研究員 (20845383)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: ベンザイン / ホウ素化反応 / エンジイン / 正宗・バーグマン環化 / 計算化学 / 有機ホウ素化合物

Outline of Final Research Achievements

o-Benzyne has been established as an intermediate in the multistep synthesis of complex natural products or as a synthetic method for acenes and highly strained molecules due to its strategic synthetic advantage in the rapid functionalization of aromatic rings. On the other hand, p-benzyne, an isomer of o-benzyne, has been actively studied both theoretically and experimentally, but studies to capture p-benzyne have been limited to functionalization by dehydrogenation from 1,4-cyclohexadiene or by dechlorination from carbon tetrachloride.
In this study, we developed a tetraborylation reaction of p-benzyne. The reaction mechanism of this reaction, which forms four carbon-boron bonds in one-shot, was approached both theoretically and experimentally to elucidate the transition state structure and its activation barriers. On the other hand, the tetraborylation products were successfully identified by single-crystal X-ray crystallography.

Free Research Field

有機合成化学

Academic Significance and Societal Importance of the Research Achievements

本研究により開発したp-ベンザインの4重ホウ素化反応は、これまで1,4-シクロヘキサジエンからの脱水素や四塩化炭素からの脱塩素による官能基化に限定されてきたp-ベンザインを捕捉する研究において新たな反応性を示す学術的に意義深いものといえる。p-ベンザインの4重ホウ素化反応では、原料と補足剤の混合溶液を加熱するだけで、1つの分子に対して一挙に4つのホウ素置換基を導入でき、その迅速さから、今後、これまで利用されてこなかったp-ベンザインを起点とする分子構築への利用が期待される。