Tags: Organic Seminar


Road to Phorbol

Phorbol, a Tigliane natural product first isolated in 1934 by Dr.Flaschenträger and Dr. Wolffersdorff, drove 17 research groups to develop the synthesis of it for over 30 years and report over 40 synthesis papers because of their potent biological activities to promote the tumor by activation of the protein kinase C and the anticancer activity.  The structure of the phorbol, first determined by Dr. Heck in 1967, was a congested tetracyclic…


The Design of Molecular Scaffolds for C-H Functionalization

Bond formation via metal-catalyzed selective C–H functionalization is well appreciated and often relies on the directing capability of the substrate. That is, the appropriate positioning of a Lewis basic functional group can present the metal catalyst center at a specific site, enabling activation of otherwise unreactive C–H bonds. The Lewis basicity of alcohols can be exploited to impart directing capabilities allowing for the capacity to…


Probing the Mechanism(s) of Sialidation Reactions Using Cation Clocks

The first part of my talk centers on the application of cation clock reactions for the determination of relative reaction kinetics in sialidation reactions. The formation of glycosidic bonds is perhaps the most important bond forming reaction in glycoscience, playing a critical role in the assembly of all glycoconjugates. In general, the control of the glycosylation reaction is a key ingredient to engineering better stereoselective…


Influence of the Side Chain Conformation on Glycosylation Selectivity in Furanosides

Glycosylation reactions stereoselectivity depends on various factors and among them, side-chain configuration and conformation have been showing significant roles in influencing the reactivity and selectivity in bicyclic glycosyl donors. Moving to monocyclic donors, this effect has been revealed in glycosylation reactions of sialic acid donor series and simple pyranoside series. We studied the extension of this concept towards furanosides by…


Glycosylation Methods in the Total Synthesis of Complex Glycosylated Natural Products

Carbohydrates are the most abundant class of molecules in the biosphere. Glycosylated secondary metabolites play a major role in carbohydrate chemistry expanding the scope of potential drug motifs. Glycosylated natural products are made out of sugars covalently O-, C-, N- or S- linked to the aglycone counterpart. In the course of synthesizing potential glycosidic therapeutics, effective and straightforward regio and stereoselective glycosylation…


Alternatives to Per- and Polyfluoroalkyl Substances for Food Packaging

Per- and Polyfluoroalkyl substances (PFAS’s) are widely used to coat paper and cardboard for food packaging because of their desirable grease, water, and heat resistant properties. However, the US FDA has raised concerns regarding the safety of these materials, citing the potential of degradation products to persist in rodents after repeated exposure, and known health risks of similar molecules. 1 In recent years, the US FDA and the EPA have…


Aminoglycoside Antibiotic Derivatization and Glycosidase Transition State Stabilization through Substrate Side Chain Restriction

The first half of the talk focuses on aminoglycoside antibiotics, highly active protein synthesis inhibitors that impact a wide range of both Gram positive and Gram negative bacteria. Though these drugs have many benefits and currently find use in the clinic, they can bring about reversible nephrotoxicity and irreversible ototoxicity. Thanks to its unusual structure, the aminoglycoside apramycin, while less active, exhibits significantly lower…


Higher Order Cycloadditions Accomplished Using Transition Metal Catalysis

Over the years, a common obstacle put in front of chemists has been the ability to construct molecules with medium sized ring structure in a high yielding and selective fashion. These higher order cyclic systems have a variety of problems synthetically with low levels of regioselective, chemoselectivity, stereoselectivity, and high levels of strain inside the scaffolds. There are very few examples of larger than six-membered rings easily…


Organo Boronates, Phosphates, and Sulfates Synthesized by Fluoride Exchange Reaction and Their Applications in Vitrimer System

Sulfur-fluoride exchange (SuFEx) reaction was first demonstrated by Sharpless and his co-workers1 in 2014. SuFEx is now considered as the second generation of click chemistry. It was established on the silicon centers, which can activate the exchange of S-F bonds for S-O bonds. A strong base, like triazabicyclodecene (TBD), was usually considered as the catalyst of SuFEx. Since then, we started to explore the possibility of the reaction between…


Light-Induced Hydrogen Sulfide Release from o-Naphthoquinone Methide Precursors (NQMPs)

Hydrogen sulfide (H2S) is one of the important gasotransmitters, a family of small gaseous signaling molecules. According to recent publications, hydrogen sulfide possesses anti-inflammatory,1 anti-tumor,2 cardiovascular protective,3 and antioxidant4 activities. However, the biological response to H2S strongly depends on H2S concentration and the specific site in the system.5 The use of H2S gas or inorganic sulfides is problematic due…
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