Structural chemistry on highly stabilized carbanions

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K08224
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Chemical pharmacy
• Research Institution: Tokyo University of Pharmacy and Life Science
• Principal Investigator: Yanai Hikaru 東京薬科大学, 薬学部, 准教授 (10408685)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 有機化学 / 薬学 / カルボアニオン / 炭素酸 / push-pullアルケン

Outline of Final Research Achievements

Carbanions are considered to be reactive and unstable chemical species. During our efforts to find 'superacidic carbon acids', we have found that gem-di(triflyl)ated carbanions are outstandingly stable and isolable as intramolecular salts. In this project, we developed an effective protocol to install the carbanionic substituent into the organic molecules. Our methodology realised a convenient synthesis of nitrogen/phosphorus betaines. Detailed structural analysis of such betaines demonstrated less basic and less nucleophilic characters of the anionic carbon atom. We also prepared several push-pull ethylenes depicted as Tf2C=C(NHR)2. Among these, dialkylated derivative showed a highly twisted structure in solid. In contrast, diaryl derivative was a compound with the nearly planar geometry. Quantum chemical crystallographic analysis of such ultimately polarised ethylenes successfully descripted the bonding situation.

Free Research Field

有機化学

Academic Significance and Societal Importance of the Research Achievements

本研究の結果，[Tf2C]-構造を含む塩の信頼できる合成手法が開発された。さらに，構造化学研究から，この種のカルボアニオンの際立って低い反応性とTf基による安定化効果の一端を解明した。上述の研究成果は，カルボアニオンを含む原子団が，概念的に全く新しい「置換基」となり得ることを意味しており，その導入に基づく機能性分子の開発が期待される。