General

Organic Chemistry Seminar: Dr. Dave Stuart, Portland State University

Mon, 2018-12-03 12:00 - 13:00
Speaker: 

Dr. David Stuart

 

 

Title: Chemical Synthesis with Diaryliodonium Salts

Abstract: Aromatic rings are ubiquitous in molecules used in health, agriculture, technology, and energy fields.  Over the past decade, diaryliodonium salts have emerged as novel aryl-transfer reagents in both metal-catalyzed and metal-free reactions.  Our research is focused on using unsymmetrical aryl(auxiliary)iodonium salts in metal-free reactions and addressing key questions of chemoselectivity in aryl transfer.  Two competing pathways will be discussed: extrusion of arynes and direct ipso-substitution.  These pathways are exploited in the development of methods that access new chemical space and expand beyond the limitations of classic SNAr.

Bio: Dave obtained his BSc (Honors) from the University of Victoria (Victoria, BC, Canada) in 2005 and his PhD at the University of Ottawa (Ottawa, ON, Canada) in 2010 under the guidance of Prof. Keith Fagnou.  After an NSERC-funded postdoc with Eric Jacobsen (Harvard), Dave began his independent career at Portland State University in 2012.  He was promoted to Associate Professor with tenure in 2018.

 

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr. Molander

inquiries rvargas@sas.upenn.edu

Organic Chemistry Seminar: Dr. Steve Malcolmson, Duke

Mon, 2018-11-05 12:00 - 13:00
Speaker: 

Dr. Steve Malcolmson

 

 

New Strategies for the Catalytic Enantioselective Synthesis of Chiral Amines and Other Challenging Scaffolds

The development of new methods for the stereoselective synthesis of chiral amines is a compelling objective in organic synthesis as these structures are found in a large number of biologically active compounds.  Yet many amine motifs remain difficult to prepare in an efficient manner, especially through complexity-building carbon–carbon bond-forming reactions and/or in atom economical ways.  In this lecture, I will describe our work in two areas of enantioselective catalysis to prepare chiral amines: 1) carbon–carbon bond formations via electrophilic additions to 2-azadienes, which act as enamine umpolung reagents, and 2) nucleophilic additions of aliphatic amines and anilines to acyclic 1,3-dienes and enynes (hydroamination).

In the former area, Cu-catalyzed reductive couplings of azadienes—virtually unexplored reagents—with ketones and imines has enabled the synthesis of challenging, sterically congested vicinal amino alcohols and diamines, while Pd-catalyzed fluoro-arylation of difluoroazadienes has permitted access to alpha-trifluoromethyl benzylic amines.  In the latter, the development of a family of electron deficient Pd–PHOX catalysts for hydrofunctionalization has enabled regio- and enantioselective addition of highly Lewis basic amines to dienes, furnishing allylic amines with a variety of allylic and olefin substituents.  Hydroaminations of enynes has led to the isolation of chiral di- and trisubstituted allenes.  Extension to diene hydroalkylation with beta-dicarbonyl-like pronucleophiles delivers myriad unsaturated carbonyl products in atom economical carbon–carbon bond-forming transformations.

 

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr. Walsh

 

inquiries rvargas@sas.upenn.edu

Organic Chemistry Seminar: Dr. Steve Zimmerman, University of Illinois

Mon, 2018-11-19 12:00 - 13:00
Speaker: 

Dr. Steve Zimmerman

 

 

New Approaches to Drug Discovery and Delivery: From Cell-Penetrating Synthetic Oligomers to Organic Synthesis Within Cells

 

A major unsolved problem in medicinal chemistry is how to get large molecules (MW >500) into cells. Cell permeability is a particularly important problem when the target is polyvalent because oligo- or polyvalent drugs invariably have large sizes and molecular weights easily in excess of 1000 and diffuse very slowly across membranes. We have been developing oligovalent therapeutic agents to target the repeating DNA and RNA sequences that cause myotonic dystrophy type 1 (DM1). This talk will describe those efforts and in particular the two approaches to get comparatively large agents into cells. The first involves polymeric metal-based catalysts that in a very broad sense mimic metalloenzymes. The ultimate goal is to have these nanoscale materials build larger, more active therapeutic agents within living cells. The water-soluble, polymeric nanoparticles we have developed use substrate binding to accelerate organic reactions and protect the metal from the competitive environment of the cell. Performing organic synthesis in the complex environment of a living cell is especially challenging. The second approach is to create inherently cell-permeable oligomeric agents. Progress on each of the above topics will be presented.

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Attached Document: 

Host: Winkler

inquiries rvargas@sas.upenn.edu

Organic Chemistry Seminar: Dr. Jeremy May, University of Houston

Mon, 2018-10-15 12:00 - 13:00
Speaker: 

Dr. Jeremy May

 

"Synthetic Discoveries from Polycyclic Natural Products"


"In  the  pursuit  of  the  synthesis  of  biologically  active  natural  products (compounds  originally  isolated  from  natural  sources),  powerful  reactions  using organic or acid catalysts (i.e., not transition metal based) have been developed. The   new   chemical   transformations   thus   made   available,   along   with   the extraordinary  chemical  compatibility  the  new  catalysts  provide,  have  enabled access to a variety of new target motifs for synthesis. Increased understanding of the catalytic mechanism and of the role of each reaction component have also led  to  additional  applications  of  the  mechanistic  paradigm  to  new  chemical"
"transformations that utilize other classes of catalysts."

 

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Attached Document: 

Host: Dr. Chenoweth

inquiries rvargas@sas.upenn.edu

Organic Chemistry Seminar: Dr. Bekka Klausen, John Hopkins

Mon, 2018-10-01 12:00 - 13:00
Speaker: 

Dr. Bekka Klausen

Title:
Unconventional Building Blocks for Functional Polymeric Materials
Abstract:
The Klausen group designs and synthesizes unconventional molecular building blocks
for the construction of diverse functional polymeric architectures. Motivated by the conviction
that the synthesis of new materials drives the discovery of new applications, this talk will
describe the synthesis and polymerization of novel hybrid inorganic-organic monomers. The
materials we prepare are expected to find application in energy science as earth abundant
quantum materials or as plastics with finely controlled physical properties.
The semiconductor silicon has revolutionized life in the last century, from the
development of computer chips to the discovery of solar cells that make telecommunication
satellites possible. The frontier for silicon research and development is at the nanoscale. The
incredible potential of nanoscale silicon arises from the attractive properties it shares with bulk
silicon, such as earth abundance and low precursor toxicity, and the distinctive optical and
electronic properties emerging at small sizes. This talk describes the design and synthesis of
new molecular forms of silicon, as well as the characterization of materials properties and the
fabrication of electronic devices based on molecular silicon.
BN 2-Vinylnaphthalene (BN2VN) is a solution to a long-standing challenge in polymer
chemistry, the copolymerization of nonpolar and polar monomers. Though the incorporation of
polar functionality into nonpolar polymers is an essential strategy for modulating physical
properties, challenges in their direct copolymerization include phase separation, significant
differences in reactivity, and the limited compatibility of polar functional groups with
polymerization catalysts. We show that BN2VN retains the reactivity of styrene, while postpolymerization
modification of the C-B bond provides hydroxyl-functionalized polymers, or
styrene-vinyl alcohol (SVA) copolymers.

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Attached Document: 

Host: Dr. Winkler

inquiries rvargas@sas.upenn.edu

Organic Chemistry Seminar: Dr. Richard Hark, Yale

Mon, 2018-09-17 12:00 - 13:00
Speaker: 

Dr. Richard Hark

"Preparation, Passion and Serendipity: Reflections on an Unfinished, Non-Traditional Career in Chemistry"

- "What do you want to be when you grow up?” is a question that is not directed solely to young children. Undergraduate and graduate students may wonder at times what they will do with their chemistry degree after graduation. In this seminar, the speaker will publicly confess that he is still trying to find the answers, even after a twenty-five-year career as a chemistry professor at liberal arts colleges. Though each person has to figure this out for themselves, the talk will provide some useful observations and general advice as Dr. Hark shares examples of how his training as a synthetic organic chemist at Penn provided the foundation on which to build an interesting and fulfilling, albeit somewhat non-traditional career.  Interspersed in the presentation will be examples of his broad research interests that include synthetic and analytical work in the fields of chemistry, forensics, geochemistry and conservation science.
Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr. Joullie

inquiries rvargas@sas.upenn.edu

Inorganic Chemistry Seminar: Dr. Michael Nippe, Texas A& M University

Tue, 2019-03-05 12:00 - 13:00
Speaker: 

Dr. Michael Nippe

Location: 

Carol Lynch lecture Hall

Chemistry Complex

Host: Dr. Tomson

Title & Abstract TBA

inquiries rvargas@sas.upenn.edu

Inorganic Chemistry Seminar: Dr.Linda Doerrer, Boston University

Tue, 2018-11-27 12:00 - 13:00
Speaker: 

Dr. Linda Doerrer

 

Title:  Teflon Coated Compounds and Their Chemistries

  Complexes surrounded by perfluorinated ligands have noticeably different physical and chemical properties than their non-fluorinated analogs.  Fluorinated ligands are well-known for their oxidative stability, and therefore make tempting targets for investigations in oxidative catalysis.  Our group has prepared a large family of first-row transition metal complexes of monodentate fluorinated alkoxide and aryoxide ligands, with the general form [M(ORF)n]m-.  These fluorinated ligands are the electronic equivalent of fluoride, based on spectrochemical studies and ligand field comparisons, but are quite distinct from [MFn]m- complexes in solubility, hydrolytic stability, and nuclearity.  More recently we have extended our investigations into bidentate systems, namely that of the perfluoropinacolate ligand.  This ligand endows its complexes with the same general characteristics as the monodentate systems investigated previously, with some additional new features as well.  In the [M(pinF)n]m- family, numerous members are air-stable and water soluble.  This talk will give an overview of our past work in homoleptic 3d metal complexes with monodentate perfluorinated ligands, and then move into published and unpublished work on perfluoropinacolate complexes.  Most recent highlights include some extraordinarily rare electronic structures, such as an S = 1 Co(III) complex, and unusual Sn(IV) and Sn(II) species. 
Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr.Schelter

inquiries rvargas@sas.upenn.edu

Inorganic Chemistry Seminar: Dr. Skye Fortier, University of Texas- El Paso

Tue, 2018-10-09 12:00 - 14:00
Speaker: 

Dr. Skye Fortier

"Metastable Metal Complexes Supported by Guanidinate Ligands"

-In this talk, we describe the chemistry of "metastable" iron and titanium complexes supported by N-donor ligands.  We have synthesized a "super bulky" guanidinate that provides kinetic stabilization to reactive metal fragments.  To this end, our efforts to synthesize and isolate complexes containing Fe=O/Fe≡N functionalities are discussed.  Additionally, we detail our work with titanium supported by guanidinate and imidazolin-2-iminato ligands and describe its reduction chemistry. For example, we have synthesized electron-rich titanium complexes, that when reduced by two-electrons, give access to Ti(II) synthons.  These Ti(II) platforms are highly reducing and exhibit unique reactivity. For instance, we observe oxidative-addition of C(sp3)-H bonds which enables catalytic transfer hydrogenation of cyclic olefins.  This reactivity and more will be presented.

Location: 

Carol Lynch Lecture Hall

 Chemistry Complex

Host: Mindiola

inquiries rvargas@sas.upenn.edu

Inorganic Chemistry Seminar: Dr. Laura Gagliardi, University of Minnesota

Tue, 2019-02-12 12:00 - 13:00
Speaker: 

Dr. Laura Gagliardi

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Tomson

Title & Abstract TBA

inquiries rvargas@sas.upenn.edu

Department of Chemistry

231 S. 34 Street, Philadelphia, PA 19104-6323

215.898.8317 voice | 215.573.2112 fax | web@chem.upenn.edu

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