Time: 13th May, 2019, 9:00-10:00 a.m.
Venue: Energy Fundamentals Building, 1st Floor Conference Room
Lecturer: Martin Oestreich, Technische Universitat Berlin
Abstract:
This talk tells the story of how our work on tamed silicon cations led us to introduce the new concept of ionic transfer hydrosilylation, even with monosilane! The electron-deficient boron Lewis acid tris(pentafluorophenyl)borane catalyzes the release of hydrosilanes from cyclohexa-2,5-dien-1-yl-substituted silanes. The same boron catalyst will then activate the Si-H bond for the reaction with representative pi- and sigma-donating substrates. The net transformation is a transfer hydrosilylation. That strategy also enables the related hydrogenation and even transfer hydrocyanation, and has been extended to Bransted acid-catalyzed transfer hydrohalogenation processes.
The catalytic generation of silylium ions by cooperative Si-H bond activation will also be presented, including a detailed mechanistic analysis of the heterolytic Si-H bond cleavage. The new catalytic entry into these main-group electrophiles is of broad synthetic utility as highlighted by electrophilic C-H bond silylation, borylation, and stannylation. Also, additional approaches to Friedel-Crafts-type C-H silylation and borylation will be discussed.
Introduction：
Martin Oestreich is Professor of Organic Chemistry at the Technische Universitat Berlin. His appointment was supported by the Einstein Foundation Berlin. He received his diploma degree with Paul Knochel (Marburg, 1996) and his doctoral degree with Dieter Hoppe (Münster, 1999). After a two-year postdoctoral stint with Larry E. Overman (Irvine, 1999-2001), he completed his habilitation with Reinhard Brückner (Freiburg, 2001-2005) and was appointed as Professor of Organic Chemistry at the Westfalische Wilhelms-Universitat Münster (2006-2011). He also held visiting positions at Cardiff University in Wales (2005), at The Australian National University in Canberra (2010), and at Kyoto University (2018). Martin Oestreich’s research focuses on main-group elements, silicon in particular, in synthesis and catalysis. His early work centered around the use of silicon-stereogenic silicon reagents in asymmetric catalysis, and his laboratory continues to employ them as stereochemical probes in mechanistic investigations. His research group made fundamental contributions to catalytic carbon-silicon bond formation with nucleophilic and, likewise, electrophilic silicon reagents, and Martin Oestreich is probably best known for his work in silylium-ion chemistry. Recent accomplishments of his laboratory include Friedel-Crafts-type C-H silylation, transfer hydrosilylation, and kinetic resolution of alcohols by enantioselective silylation.
Contact: HU Yan-Cheng Group 02T4
Phone: 84771230