Study of a Diene / Dienophile System for Quantitative Determination of Activation Parameters for the Ruthenium-Sandwich Complex Acceleration of Diels-Alder Reaction
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Authors
Ackerman, Sebastian
Date of Issue
2023-04-28
Type
Presentation
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Abstract
The Diels-Alder reaction involves two organic compounds possessing π systems, a diene and a dienophile, to form a 6-membered ring with a carbon-carbon π bond. Primarily used as a synthetic tool to create various medicinal compounds, Diels-Alder reactions can proceed at a reasonable rate by attaching an electron-withdrawing group (EWG) to the dienophile. Previous research by Carroll students in Dr. Hitt’s research program have shown (h5-cyclopentadienyl)ruthenium(II)(h6-aryl) substituents, [CpRu(h6-aryl)+], to be an effective EWG by facilitating the reaction of ethyl trans-cinnamate and 2,3-dimethyl-1,3-butadiene. For example, reacting [CpRu(h6-ethyl trans-cinnamate)]PF6 with 2,3-dimethyl-1,3-butadiene affords DA adduct under reflux conditions with nitromethane while reacting ethyl trans-cinnamate with 2,3-dimethyl-1,3-butadiene afforded no product after 8 days of reflux. More detailed kinetic studies of the reaction, however, are hampered by the volatility of 2,3-dimethyl-1,3-butadiene which makes it difficult to control solute concentration. As a remedy, anthracene has been identified as a possible replacement as it is a crystalline, non-volatile solid at room temperature thus making its concentration easier to maintain under the high temperature reaction conditions. Herein, we report on our progress of using anthracene as a diene and [CpRu(h6 -ethyl trans-cinnamate)]PF6 as a dienophile.