2019年12月10日新加坡南洋理工大学Pak-Hing Leung教授学术报告

报告摘要：

     Both the PC-palladacycle Cat-1 and PCP-pincer complex Cat-2 are efficient catalysts for P-H and As-H addition reactions across C=C bonds. However, they show very different reactivity and selectivity in these addition reactions. For example, when Cat-1 was used as the catalyst, addition of the Ph₂P-H bond to α,β,γ,δ-unsaturated malonate ester gave the 1,4-addition product exclusively. When the same reaction was catalysed by Cat-2, only the 1,6-addition product was generated. The catalyst-product specificity is due to the fact that the two catalysts operate via different reaction mechanisms. Cat-1 interacts with both reacting species simultaneously during the course of the bond formation process while the pincer catalyst operates via an inter-molecular mechanism by activating only the P-H moiety. The various optically active phosphine products generated from the P-H addition reactions can be effectively used as chiral auxiliaries to form other transition metal catalysts. Furthermore, despite the fact that both arsenic and phosphorus are group 15 elements, very different reactivities were observed when the two catalysts were employed in the analogous metal catalysed As-H addition reactions. Further details on this interesting catalyst-substrate-product specificity will be presented in the seminar.

报告人简介：

        Pak-Hing Leung received his Ph.D. from the Australian National University in 1986 under the supervision of Professor Stanley Bruce Wild, followed by post-doctoral research with late Professor Brice Bosnich at both the University of Toronto and the University of Chicago until 1989. He then joined the National University of Singapore (NUS) and was a professor there until 2005 when he was invited to be the founding head of the Chemistry Division and other senior university management positions in the new School of Physical and Mathematical Sciences at the Nanyang Technological University (NTU). His research interests lie primarily in the field of synthetic stereochemistry, organometallic compounds with particular focus on their applications in asymmetric catalysis. He has also explored the application of chiral gold-phosphine complexes in anti-cancer research. He has published more than 180 peer reviewed articles, a book chapter and several PCT-patents. To date, he has supervised about 50 PhD and 10 MSc graduates in Singapore. Professor Leung has received numerous academic awards, including 17 teaching excellence awards from both NUS and NTU. He was awarded an outstanding University researcher award by NUS in 1998 for his work in asymmetric catalysis. He was the NTU representative in the Singapore Standards Council (SPRING) between 2014-2017. Externally he is holding the advisory positions in the Singapore Polytechnic and in the Postgraduate Chemical Engineering Program at the Mahidol University, Thailand.