一、报告时间

2025年5月9日下午4:00

二、报告地点

化学老楼1109教室

三、报告主题

Chiral Cationic Ion Pair Catalysis using Guanidiniums

四、主讲人介绍

TAN, Choon Hong

Prof. Tan received his BSc (Hons), First Class from the National University of Singapore in 1995 and completed his PhD from the University of Cambridge in 1999. Following that, he carried out two years postdoctoral training at the Department of Chemistry and Chemical Biology, Harvard University. Subsequently, he worked as a Research Associate at Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School for another year before joined the Department of Chemistry, National University of Singapore as Assistant Professor in 2003. He was then promoted to Associate Professor in 2010. He joined Nanyang Technological University in 2012 as an Associate Professor and was promoted to Full Professor in 2016. He is currently the President’s Chair Professor of Organic Chemistry at NTU. His research interest is in the field of Synthetic Organic Chemistry and Catalysis.

Professor Tan is the immediate past President of Singapore National Institute of Chemistry and current Vice-President of the Singapore National Academy of Science. He was elected to the Singapore National Academy of Science in 2020. He is recently named the recipient of the 2023 Ta-Shue Chou Lectureship Award and gave the Grubbs Institute Distinguished Lecture at the Grubbs Institute in 2024.

五、报告摘要

Chiral cations have demonstrated exceptional efficacy as phase-transfer catalysts, particularly in conjunction with inorganic basic salts like hydroxides and carbonates in base-mediated reactions. Over the past decade, we have developed several chiral cation catalysts, notably pentanidium and bisguanidinium, which have significantly advanced the field. In this report, we explore their roles in ion-pair catalysis using three distinct types of anions. First, we examine the use of fluoride to generate hypervalent silicate intermediates and its pairing with chiral cations to facilitate enantioselective reactions. Next, we delve into reactions where chiral cations work synergistically with polyoxometalates, such as tungstate and molybdate, serving as co-catalysts. Lastly, we highlight the ability of chiral cations to modulate reactions involving anionic organic sulfur salts. Key transformations, including SN2X (halogenophilic nucleophilic substitution) and the desymmetrization of sulfinates, will be discussed in detail.