New Possibilities of Sulfonium Salts in Organic Synthesis

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K05780
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Synthetic chemistry
• Research Institution: Nagasaki University
• Principal Investigator: SHIRAKAWA Seiji 長崎大学, 水産・環境科学総合研究科(環境), 准教授 (60459865)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 有機分子触媒 / 不斉合成 / 触媒設計 / 水素結合 / 硫黄触媒 / オニウム塩 / スルホニウム塩 / グリーンケミストリー

Outline of Final Research Achievements

Despite the wide synthetic utility of onium salts as reagents and catalysts, the catalytic ability of tertiary sulfonium salts has not yet been demonstrated well in organic synthesis. To create new possibilities for sulfonium salts as catalysts, we focused on the hydrogen-bonding abilities of α hydrogens on alkylsulfonium salts when we reported the use of new tetraalkylammonium salts as hydrogen-bonding catalysts. Based on the design of the ammonium salts, we focused on simple cyclic trialkylsulfonium salts. The catalytic ability of sulfonium salts was superior to that of the related ammonium salts. We have also demonstrated that chiral tertiary sulfonium salts can promote asymmetric reactions. Binaphthyl-modified bifunctional sulfonium salts were efficient catalysts for the asymmetric reactions under base-free phase-transfer conditions. As far as could be ascertained, this is the first example of a highly enantioselective reaction catalyzed by chiral sulfonium salts.

Free Research Field

有機合成化学、グリーンケミストリー

Academic Significance and Societal Importance of the Research Achievements

これまで未開拓であった、第三級スルホニウム塩の触媒としての機能を引き出すことに成功し、有機硫黄化学の新たな可能性を示した。本研究は、地球上に豊富に存在する硫黄元素の特性を引き出した研究であり、元素戦略の観点から重要な研究である。また、環境に調和した新たな精密有機合成手法を確立しており、有用化合物のグリーンケミストリーに根ざした実用的合成へ繋がると期待される。