Monthly Archives: September 2023

Chemistry seminar: Sharon Neufeldt, Montana State University

Sharon Neufeldt, Montana State University

“Controlling Selectivity in Cross-Couplings of Dihalo(hetero)arenes”

Monday, September 25
11:30 a.m.
Engineering Computer Science Building, Room 116
and Zoom https://uvic.zoom.us/j/83657240884?pwd=3pDZp5892dS4gsAKoaplX1t2j9kgbh.1

Abstract:  Pd-catalyzed cross-coupling reactions are among the most powerful transformations in organic synthesis. Nevertheless, controlling selectivity can be problematic when employing substrates with more than one (pseudo)halide. Two such challenges are discussed in this presentation. Overfunctionalization is one challenge: it can be difficult to control even with carefully tuned stoichiometry. We have investigated the mechanistic origin of ligand effects on controlling between mono- versus diarylation in Suzuki cross-couplings. Ligand sterics influence the competition between two pathways: a bimolecular mechanism for dissociation of the mono-coupled product from Pd versus a second oxidative addition event. Our studies provide insight into strategies to minimize (or maximize) polyfunctionalization in cross-coupling reactions. This presentation will also describe another selectivity challenge that arises with dihalogenated heteroarenes. Most dihaloheteroanes undergo cross-coupling reactions with a strong preference for breaking one C–halide bond over the other. For a few such substrates, catalyst-controlled approaches have been described that enable inversion of the conventional site selectivity. However, 2,4-dihalopyrimidines are particularly resistant to change: they always undergo cross-coupling at C4, and SNAr reactions also tend to favor that site. We recently developed a method to preferentially cross-couple at the C2 position of 2,4-dihalopyrimidines. The selectivity is surprising, and preliminary mechanistic investigation suggests that C—X cleavage does not take place through a traditional oxidative addition mechanism.

Visit https://events.uvic.ca/chemistry/ for the full list of 2023-2024 Chemistry seminars.

Support for First Generation Students

First Generation Mentor Program

We want to let you know about an exciting new support opportunity for students who were the first in their family to attend university, sometimes referred to as “first generation” or “first-gen”. Over the past year, we have created a mentorship program called “First in Class”. It consists of faculty all across campus who were themselves first gen students, who want to offer extra support and guidance to students who are navigating the unfamiliar world of the university. We know firsthand how challenging it can be to not have family to turn to for advice about courses, careers, and all of the unfamiliar rules and norms of higher education.

If you are interested in joining our program and finding a mentor, please go to: https://www.surveymonkey.ca/r/J9J523V  This short survey will tell you a bit more about our program and also invite you to sign up. Once we receive your email address/survey responses, we can put you on our contact list and advise you how to seek your mentor.

We are also planning faculty/student social events through the year, and the first one is on October 12th from 5-7pm (on campus). Details will be provided when you contact us! We look forward to hearing from you!

Catherine Léger (FRAN), Colette Smart (PSYC), and Su Urbanczyk (LING)