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Full-Text Articles in Chemistry
Fluoride-Promoted Ligand Exchange In Diaryliodonium Salts, Bijia Wang, Ronald Cerny, Shriharsha Uppaluri, Jayson J. Kempinger, Stephen G. Dimagno
Fluoride-Promoted Ligand Exchange In Diaryliodonium Salts, Bijia Wang, Ronald Cerny, Shriharsha Uppaluri, Jayson J. Kempinger, Stephen G. Dimagno
Stephen DiMagno Papers
Diaryliodonium salts are shown to undergo rapid, fluoride-promoted aryl exchange reactions at room temperature in acetonitrile. Aryl exchange is shown to be exquisitely sensitive to the concentration of fluoride ion in solution; fast exchange is observed as the fluoride concentration approaches a stoichiometric amount at 50 mM substrate concentration. The reaction is slowed, but not halted if benzene is the solvent, indicating that free fluoride ion or a four-coordinate anionic I(III) species may be responsible for the exchange. The fluoride-promoted aryl exchange reaction is general and allows direct measurement of the relative stabilities of diaryliodonium salts featuring different aryl substituents. …
Controlling Reductive Elimination From Novel I(Iii) Salts Using A Secure Method, Joseph W. Graskemper
Controlling Reductive Elimination From Novel I(Iii) Salts Using A Secure Method, Joseph W. Graskemper
Department of Chemistry: Dissertations, Theses, and Student Research
Positron Emission Tomography (PET) is a valuable clinical, research, and diagnostic technique for human and animal organ imaging. The current market for PET in the United States is $500 million per year and is projected to be $5.4 billion per year globally by 2015. To synthesize labeled radiotracers, we are most interested in using 18F as the isotope of choice because it is a nearly ideal positron emitting radionuclide.
Electron-rich aromatic substrates can be particularly difficult to fluorinate. We show that reductive elimination of I(III) diaryliodonium salts provide increased fluorination of electron-rich aromatic substrates. Modest yields of fluorinated product …
Functionalization Of Aromatic Organic Molecules By Anhydrous Flourides And By Reductive Elimination Of Iodine(Iii), Bijia Wang
Department of Chemistry: Dissertations, Theses, and Student Research
Solution phase reactivity of nucleophilic fluoride reagents is attenuated by ion-pairing interactions. 1H-19F HOESY competition experiments permit generation of a fluoride ion affinity scale in the weak-binding regime. Direct DFT calculations of ion pair interaction energies as well as calculated cation electrostatic potential maps can be used to predict solution phase ion pairing tendencies for closely related ammonium cations. It was found by studying the decomposition of tetra-substituted ammonium cations by fluoride that: 1) rates of E2 decomposition is faster than the SN2 pathway; 2) aryl substituents destabilize the cations; 3) steric strain tends to …
Regiospecific Reductive Elimination From Diaryliodonium Salts, Bijia Wang, Joseph W. Graskemper, Linlin Qin, Stephen G. Dimagno
Regiospecific Reductive Elimination From Diaryliodonium Salts, Bijia Wang, Joseph W. Graskemper, Linlin Qin, Stephen G. Dimagno
Stephen DiMagno Papers
StereoElectronic Control of Unidirectional Reductive Elimination (SECURE) is provided by the cyclophane substituent on iodine(III). Computational and experimental studies demonstrate that out of plane steric bulk strongly destabilizes the reductive elimination transition state, and leads to regiochemical control. This approach should be general for high valent main group and transition metal ions.