POSTER SESSION

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Dearomative Synthetic Entry Into the Altemicidin Alkaloids, by Claire Magnani

Dearomative Synthetic Entry Into the Altemicidin Alkaloids, by Claire Magnani

Altemicidin and related Streptomyces-derived monoterpene alkaloids possess, highly-polar, dense azaindane cores as well as potent cytotoxic and tRNA synthetase inhibitory properties. The congested a-amino acid motif decorating their presumed ten-carbon iridoid-like core structure has proven both a synthetic challenge and biosynthetic mystery. This work relates the synthetic process which culminated in a distinct and concise synthesis of altemicidin from simple chemical feedstocks...

Divergent Stereochemical Outcomes in the Insertion of Donor/Donor Carbenes... by Sarah Dishman

Divergent Stereochemical Outcomes in the Insertion of Donor/Donor Carbenes... by Sarah Dishman

Intramolecular C–H insertions with donor/donor dirhodium carbenes provide a concise and highly stereoselective method to set two contiguous stereocenters in a single step. Herein, we report the insertion of donor/donor carbenes into stereogenic carbon centers allowing access to trisubstituted benzodihydrofurans in a single step. This study illuminates, for the first time, the stereochemical impact on the carbene center and delineates the structural factors that enable control over both...

Progress Toward the Total Synthesis of (+)-Fomannosin, by Ciara Mary Ordner

Progress Toward the Total Synthesis of (+)-Fomannosin, by Ciara Mary Ordner

Fomannosin, first isolated in 1967, deviates from other members of the protoilludane family with a unique, conjugated cyclobutene moiety and in its instability to acid or base. This natural product is reported to have phytotoxic and antimicrobial activity, most notably against Pinus tadea seedlings and Chlorella pyrenoidosa. The current synthetic strategy hinges upon two key transformations: an asymmetric allylic alkylation to form two contiguous stereocenters, of which one is quaternary...

Studies Toward the Total Synthesis of Briareolide J, by Joshua Daniel Farr

Studies Toward the Total Synthesis of Briareolide J, by Joshua Daniel Farr

The briaranes are a diverse class of diterpenoids isolated from marine invertebrates that are distinguished by an unusual trans-6–10 ring fusion. Since the initial isolation 1977, over 800 unique members have been disclosed, many of which possess interesting structural features, such as halogen-bearing stereocenters and additional ring fusions, and novel bioactivities. However, despite numerous synthetic endeavors over the last 25 years, no completed total synthesis of any briarane has been...

Lewis acid catalyzed addition of prochiral E and Z allyl nucleophiles to... by David Gutierrez

Lewis acid catalyzed addition of prochiral E and Z allyl nucleophiles to... by David Gutierrez

The Lewis acid catalyzed addition of prochiral E and Z allyl nucleophiles to a-chiral alkoxy N-tosyl aldimines is de-scribed. Alkene geometry is selectively transferred to the newly formed carbon-carbon bond, resulting in stereochemical control of C2, C3, and C4 of the resulting 2-alkoxy,3-N-tosyl, 4-alkyl-5-hexenes. The C3 and C4 diastereoselectivity (dr) is influenced by the geometry of the alkene, size of N-sulfonyl substituent, and steric bulk of the substituted a-alkoxy ether group...

A systematic investigation of the influence of inherent asymmetry of chiral N-tosyl... by Anna Lo

A systematic investigation of the influence of inherent asymmetry of chiral N-tosyl... by Anna Lo

A systematic investigation of the influence of inherent asymmetry of chiral N-tosyl imines on the diastereoselective outcomes of Lewis-acid mediated nucleophilic addition reactions is presented. 1,2 asymmetric induction is pronounce in α-chiral imines when nucleophilic addition is mediated by ZnBr2 and BF3·OEt2, leading to either syn or anti-alkenyl sulfonamides respectively, with >95:5 diastereoselectivities. The observed selectivities do not adhere to the prevailing predictive models that...

Enantioselective Total Synthesis of the Archaeal Lipid Parallel GDGT-0... by Isaac Doran Falk

Enantioselective Total Synthesis of the Archaeal Lipid Parallel GDGT-0... by Isaac Doran Falk

The cell membranes of archaeal extremophiles feature unique lipids which are proposed to enable survival in conditions inhospitable to most other organisms. In contrast to canonical fatty acid-based lipids, these extremophiles use polyisoprenoid-derived units connected via an ether linkage to glycerol head groups to form macrocyclic molecules known as glycerol dibiphytanyl glycerol tetraether (GDGT) lipids. There is significant structural variation within these bipolar lipids with...

Organic Synthesis

Revisiting the X-ray absorption iron K-edge spectroscopy of the Fe(IV)2... by Augustin Braun

Revisiting the X-ray absorption iron K-edge spectroscopy of the Fe(IV)2... by Augustin Braun

In the first step of the metabolic cycle of methanotrophic bacteria, the copper-containing particulate methane monooxygenase (pMMO) and diiron-containing soluble methane monooxygenase (sMMO) convert methane into methanol by activating the strong C-H bond of methane under ambient conditions. The structure of the catalytically competent intermediate of sMMO, named Q, has been heavily studied over the last 30 years. The early consensus was a close core structure with 2 bridging oxo ligands...

Fitness landscape-guided engineering of virus-like particles for drug delivery, by Paige Pistono

Fitness landscape-guided engineering of virus-like particles for drug delivery, by Paige Pistono

Protein-based nanoparticles are an attractive candidate for drug delivery, as they can be genetically engineered and chemically modified with new functionalities and are generally cheap to produce and biodegradable. Virus-like particles (VLPs) are especially promising platforms for expanding the repertoire of therapeutics that can be delivered effectively, as they can deliver multiple copies of a molecule to a cell at higher concentrations than could be achieved via systemic delivery of a...

Discovery of conformation-selective cyclic peptide inhibitors targeting Gαs, by Shizhong Dai

Discovery of conformation-selective cyclic peptide inhibitors targeting Gαs, by Shizhong Dai

The G protein-coupled receptor (GPCR) cascade leading to production of the second messenger cAMP is replete with pharmacologically targetable receptors and enzymes with the exception of the stimulatory G protein α subunit, Gαs. GTPases remain largely undruggable given the difficulty of displacing high affinity guanine nucleotides and the lack of other drug binding sites. We explored a chemical library of 1012 cyclic peptides in order to expand the chemical search for inhibitors of this enzyme...

Progress towards an iron-porphyrin-based antidote for carbon monoxide poisoning, by Dan Droege

Progress towards an iron-porphyrin-based antidote for carbon monoxide poisoning, by Dan Droege

Carbon Monoxide (CO) poisoning results in over 50,000 emergency department visits every year in the US and is one of the most common forms of poisoning worldwide. Oxygen is still the accepted treatment for CO poisoning but, depending on the amount of CO inhaled and the time it takes to receive treatment, O2 treatment may not be enough to prevent death or long-term damage. Despite the great need, there is no established antidote for CO poisoning. The toxicity of CO is derived from its...

Removal of Metal Inhibitor in the Active Site to Monitor Adenine Excision... by Merve Demir

Removal of Metal Inhibitor in the Active Site to Monitor Adenine Excision... by Merve Demir

The DNA glycosylase MutY prevents G:C to T:A transversion mutations by removing misincorporated adenine across 8-oxo-guanine (OG), an oxidation product of guanine. In this study, we explored the role of an active site residue N146 in the adenine excision mechanism using site-directed mutagenesis, kinetic studies and X-Ray crystallography. In crystal structures of Geobacillus stearothermophilus (Gs) MutY, N146 forms hydrogen bonds with the DNA phosphate backbone and catalytic residue D144 that...

An Innovative Approach to the Planet’s Degrading Environments... by Selin Kocalar & Aylin Salahifar

An Innovative Approach to the Planet’s Degrading Environments... by Selin Kocalar & Aylin Salahifar

To address environmental stressors such as heavy metal contamination, soil salinity, and rising temperatures, the relationship between rhizobacterial strain Bacillus cereus and survival of Arabidopsis thaliana under abiotic stress was probed and optimized through genetic engineering. Plant growth measurements, chlorophyll content studies by UV-visible spectrophotometry, profiles of 15 key metabolites using gas chromatography-mass spectrometry, quantitative gene expression screens...

Chemical Biology & Bioinorganic

Mechanism and Origins of Regioselectivity of CoIII-catalyzed C-6 Alkenylation... by Supreeth Prasad

Mechanism and Origins of Regioselectivity of CoIII-catalyzed C-6 Alkenylation... by Supreeth Prasad

The mechanism, and regioselectivity of Co-catalyzed alkenylation of 2-pyridone with terminal alkynes (Ravikumar et al. J. Org. Chem. 2021, 86, 14, 9444–9454) is probed and rationalized from density functional theory calculations. Four possible permutations of the ligand system (i.e. [AcOHCp], [AcOHCp*], [PivOHCp], and [PivOHCp*]) are examined. Results indicate that the bulkier group on the alkyne distal to the pyridone is more favorable for the overall catalytic cycle. The mechanism is found...

Can Dirhodium Complexes Catalyze Cyclopropanation of Cycloheptatriene Diazo... by Croix Laconsay

Can Dirhodium Complexes Catalyze Cyclopropanation of Cycloheptatriene Diazo... by Croix Laconsay

Density functional theory (DFT) calculations were used to explore the possibility that 7-diazo-cycloheptatriene compounds might undergo an intramolecular cyclopropanation to substituted semibullvalenes. Our computational study reveals that, in theory, it is possible to do so, though side reaction pathways explored suggest that beta-hydride elimination to heptafulvenes may pose a challenge to realizing an efficient synthesis to semibullvalenes. The cycloheptatriene - norcaradiene equilibrium...

Monodispersity through self-assembly: non-equilibrium protocols and molecular... by Lucie Liu

Monodispersity through self-assembly: non-equilibrium protocols and molecular... by Lucie Liu

Monodispersity is crucial for lipid nanoparticles (LNPs) to function as safe and effective drug carriers. In order to achieve size control, most LNPs are fabricated in microfluidic channels and rapidly cooled post-fabrication. In the poster, I will describe a recent experiment of a photo-catalyzed synthesis of a model lipid nanoparticle without the use of microfluidics but still exhibits monodispersity and long-term stability at moderate temperatures. I will present the theoretical...

Catalyst-Controlled Regiodivergence in Rearrangements of Indole-Based Onium Ylides, by Volga Kojasoy

Catalyst-Controlled Regiodivergence in Rearrangements of Indole-Based Onium Ylides, by Volga Kojasoy

Catalysts can play an important role in selectivity in molecular rearrangements that are traditionally unselective. We studied the origins of catalyst-controlled regiodivergence in [2,3]- and [1,2]-rearrangements of indole-based onium ylides derived from indole methylethers and diazoesters. As our initial target for the rearrangements, we chose the indole scaffold because of its prevalence in many natural products and medicinally valuable compounds. With the proper choice of catalyst system...

Separation of Enantiomers: A Screw Model Mechanism, by Anderson Da Silva Duraes

Separation of Enantiomers: A Screw Model Mechanism, by Anderson Da Silva Duraes

We present a model to explain the mechanism behind enantiomeric separation under either shear flow or local rotational motion in a fluid (https://pubs.acs.org/doi/10.1021/acs.jpcb.1c07127). Local vorticity of the fluid imparts molecular rotation that couples to translational motion, sending enantiomers in opposite directions. Translation-rotation coupling of enantiomers is explored using the molecular hydrodynamic resistance tensor, and a molecular equivalent of the pitch of a screw is used...

Structure-Based Drug Design and Lead Optimization of NOP-MOP agonists, by Arpit Doshi

Structure-Based Drug Design and Lead Optimization of NOP-MOP agonists, by Arpit Doshi

Nociceptin or orphanin FQ (N/OFQ) is an endogenous peptide ligand of the fourth member of the opioid receptor family, namely the nociceptin opioid receptor (NOP). The functional activity resulting from N/OFQ or other agonists binding to NOP has been shown to be involved in several central nervous system pathways regulating pain, reward, feeding, anxiety, motor control and learning/memory. Both full or partial selective NOP agonists as well as bifunctional agonists at the NOP and mu opioid...

Computational & Medicinal Chemistry