SEP 16, 2015 12:00 PM PDT

The Functionalization of C-H Bonds

Speaker
  • Professor of Chemistry, University of Illinois
    Biography
      M. Christina White was born in Athens, Greece. She received a B.A. degree in biochemistry with highest honors from Smith College working with Stuart Rosenfeld. After a one-year stint in the biology graduate program working with Christian Anfinsen, she received her Ph. D. degree from Johns Hopkins University in chemistry with Gary Posner as an ACS Medicinal Chemistry predoctoral fellow. She conducted postdoctoral studies at Harvard University with Eric Jacobsen as an NIH postdoctoral fellow and is currently a Professor of Chemistry at the University of Illinois at Urbana-Champaign.



      The White group aims to discover selective, catalytic C-H oxidation, amination, and alkylation reactions for use in organic synthesis. They have contributed novel palladium/sulfoxide [(http://en.wikipedia.org/wiki/White_catalyst), Aldrich, Strem, and TCI] and iron catalysts [(http://en.wikipedia.org/wiki/White-Chen_Catalyst) Aldrich,Strem] that functionalize allylic and aliphatic C-H bonds under preparative conditions with predictable site-selectivities and without the requirement for directing groups. These catalysts led to the discovery of a code for differential reactivity between C-H bonds based on electronic, steric, and stereoelectronic effects that has been demonstrated to be general across a range of different aliphatic C-H oxidation reactions. Using these catalysts, seminal demonstrations of site-selective and -divergent C-H oxidations in complex molecules pioneered the concept of late-stage functionalization.

    Abstract
    Among the frontier challenges in chemistry in the 21st century are the interconnected goals of increasing control of chemical reactivity while synthesizing and diversifying complex molecules with higher efficiency. Traditional organic methods for installing oxidized functionality rely heavily on sequential acid-base reactions that require extensive functional group manipulations (FGMs). In contrast, nature routinely uses allylic and aliphatic C-H oxidation methods, generally mediated by heme and non-heme iron monooxygenase enzymes, to directly install oxidized functionality into preformed frameworks of complex molecules. Due to their ubiquity in complex molecules and inertness to most organic transformations, C-H bonds have typically been ignored in the context of methods development for total synthesis. The exceptions to this rely on substrate directing groups to facilitate site-selectivity and reactivity. The discovery and development of catalysts for the direct installation of oxygen, nitrogen and carbon into allylic and aliphatic C-H bonds are discussed. Unlike Nature which uses elaborate shape or functional group recognition active sites, these small molecule catalysts utilize differential sensitivity to the C-H bond electronics, sterics, and stereoelectronic environment to achieve predictable site-selective and -divergent oxidations in complex molecule settings- and without the requirement for directing groups. Using these catalysts a code for site-selective C-H reactivity has been delineation that has proven to be highly general across a range of C-H oxidation catalysts and reactions. Our current understanding of these interactions and the development of a catalyst reactivity model that calculates and even predicts the major site of oxidation as well as the magnitude and direction of the site-selectivity in complex substrates as a function of catalyst will be described.

    Show Resources
    You May Also Like
    MAY 11, 2021 10:00 AM PDT
    Add to Calendar Select one of the following: iCal Google Calendar Outlook Calendar Yahoo Calendar
    C.E. CREDITS
    MAY 11, 2021 10:00 AM PDT
    Add to Calendar Select one of the following: iCal Google Calendar Outlook Calendar Yahoo Calendar
    Date: May 11, 2021 Time: 10:00zm PDT Your samples are some of the most valuable assets in the laboratory. After spending countless hours on extraction and preparation, your conclusions could...
    DEC 02, 2020 8:00 AM PST
    C.E. CREDITS
    DEC 02, 2020 8:00 AM PST
    DATE: December 2nd, 2020 TIME: 08:00am PDT, 11:00pm EDT Bioreactors and shakers are used to cultivate microorganisms, plant, insect, and mammalian cells in different volumes. Upscaling of pr...
    JUN 09, 2021 7:00 AM PDT
    Add to Calendar Select one of the following: iCal Google Calendar Outlook Calendar Yahoo Calendar
    C.E. CREDITS
    JUN 09, 2021 7:00 AM PDT
    Add to Calendar Select one of the following: iCal Google Calendar Outlook Calendar Yahoo Calendar
    Date: June 9, 2021 Time: 09 June 2021, 7am PDT, 10am EDT, 4pm CEST cells with dramatic implications on the validity of past cell culture related research. The fact that at least 509 cell lin...
    DEC 16, 2020 8:00 AM PST
    C.E. CREDITS
    DEC 16, 2020 8:00 AM PST
    Date: December 16, 2020 Time: 8:00am (PST), 11:00am (EST) Molecular imaging of living specimens offers a means to draw upon the growing body of high-throughput molecular data to better under...
    APR 01, 2021 8:00 AM PDT
    C.E. CREDITS
    APR 01, 2021 8:00 AM PDT
    Date: April 01, 2021 Time: 8:00am (PST), 11:00am (EST) Generating therapeutic antibodies is far more challenging than obtaining antibodies that merely recognize their targets. Engineering po...
    MAR 16, 2021 10:00 AM PDT
    C.E. CREDITS
    MAR 16, 2021 10:00 AM PDT
    Date: March 16, 2021 Time: 10:00am (PST) Scientific progress and breakthroughs today are often too expensive for most institutions to acquire. Each year, the National Institutes of Health (N...
    Loading Comments...
    Show Resources
    Attendees
    • See more