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Exploring cation-π interactions in a sophomore Organic Chemistry Laboratory experiment
Title
Exploring cation-π interactions in a sophomore Organic Chemistry Laboratory experiment.
Creator
Horowitz, Andrew, Rucco, Dominic, St. Germain, Elijah, Lepore, Salvatore D., Rezler, Evonne
Abstract/Description
An Organic Chemistry Lab experiment is being developed and adapted from work recently published by Maity and Lepore [1] investigating the cyclization of substituted β-alkynyl hydrazines to yield azaproline derivatives. The mechanism of this reaction is putatively driven by cation-π interaction of alkynyl hydrazine with a tetrabutylammonium ion. This experiment will present students with a cutting-edge research concept to explore the role of tetrabutylammonium in the cyclization of substituted...
Show moreAn Organic Chemistry Lab experiment is being developed and adapted from work recently published by Maity and Lepore [1] investigating the cyclization of substituted β-alkynyl hydrazines to yield azaproline derivatives. The mechanism of this reaction is putatively driven by cation-π interaction of alkynyl hydrazine with a tetrabutylammonium ion. This experiment will present students with a cutting-edge research concept to explore the role of tetrabutylammonium in the cyclization of substituted β-alkynyl hydrazines. Reaction kinetics will be probed by thin-layer chromatography and azaproline derivative product(s) will be characterized by IR spectroscopy. Ultimately, our goal is to implement a modern research-based, cost-effective, and safe bioorganic experiment into Florida Atlantic University’s undergraduate Organic Chemistry Laboratory curriculum.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA0005024
Subject Headings
College students --Research --United States.
Format
Document (PDF)
Synthesis and Bioactivity Investigation of Bridged Bicyclic Compounds and a Mechanistic Investigation of a Propargyl Hydrazine Cycloaddition Catalyzed by an Ammonium Salt
Title
Synthesis and Bioactivity Investigation of Bridged Bicyclic Compounds and a Mechanistic Investigation of a Propargyl Hydrazine Cycloaddition Catalyzed by an Ammonium Salt.
Creator
St.Germain, Elijah, Lepore, Salvatore D., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
Abstract/Description
We report the development of a general route to the synthesis of [4.3.1], [3.3.1], an especially [3.2.1] bicyclic compounds structurally related to vitisinol D, a natural product. This allows for diastereoselective synthesis of bicyclic compounds with five adjacent chiral centers. This route was employed in a preliminary SAR investigation into the neuroprotectant effect of small molecules in an in vivo experiment measuring the degree of restorative effect of synaptic transmission in the...
Show moreWe report the development of a general route to the synthesis of [4.3.1], [3.3.1], an especially [3.2.1] bicyclic compounds structurally related to vitisinol D, a natural product. This allows for diastereoselective synthesis of bicyclic compounds with five adjacent chiral centers. This route was employed in a preliminary SAR investigation into the neuroprotectant effect of small molecules in an in vivo experiment measuring the degree of restorative effect of synaptic transmission in the neuromuscular junction of Drosophila melanogaster larvae under acute oxidative stress. One of the compounds exhibited intriguing potential as a neuroprotectant and outperformed resveratrol in restoring synaptic function under oxidative stress. The hypothesis that bridged bicyclic compounds may hold promise as drug scaffolds due to their conformational rigidity and ability to orient functional appendages in unique orientations is developed. The second focus is a mechanistic investigation into a tetrabutylammoniumcatalyzed cycloaddition as evidence of a novel ammonium-alkyne interaction. A carbamate nitrogen adds to a non-conjugated carbon–carbon triple bond under the action of an ammonium catalyst leading to a cyclic product. Studies in homogeneous systems suggest that the ammonium agent facilitates cyclitive nitrogen–carbon bond formation through a cation–π interaction with the alkyne unit. Using Raman spectroscopy, this cation–π interaction is directly observed for the first time. DFT modeling elucidated the mechanistic factors in this cycloaddition. A teaching experiment was developed based on this mechanistic investigation. Control experiments were employed to demonstrate the testing of two alternative mechanistic hypotheses. Cyclization reactions were performed with a soluble base (sodium phenoxide) with and without tetrabutylammonium bromide under homogeneous conditions. Students observed that ammonium salt accelerates the reaction. They were encouraged to develop a testable hypothesis for the role of the ammonium salt in the cyclization mechanism: typical phase transfer or other. IR spectroscopy was used to directly observe a dose dependent shift of the alkyne stretching mode due to a cation−π interaction. Undergraduates were able to employ the scientific method on a contemporary system and see how data are generated and interpreted to adjudicate between rival hypotheses in a way that emulates authentic and current research in a lab setting.
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Date Issued
2018
PURL
http://purl.flvc.org/fau/fd/FA00013100
Subject Headings
Bicyclic compounds., Ammonium salts., Cycloaddition Reaction.
Format
Document (PDF)