Browsing by Subject "hypervalent iodine"

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    Preparation and structure of diaryliodonium salts with hydroxy and carboxylic acid groups
    (2022-01) Larson, Scott
    Toxic transition metals are often used in organic synthesis reactions, which poses a potential hazard in their applications, especially medicinally and environmentally. A potential solution to this problem is to use trivalent iodine in place of toxic transition metals in synthesis. One class of compounds that could be specifically useful in toxic transition metal replacement is pseudo-cyclic iodonium triflate salts. This project focuses on developing the best method and scope for the preparation of diaryliodonium salts from iodosobenzoic acid-triflate (IBA-OTf) and (3-acetoxyphenyl)-3-iodanediyl diacetate compounds. These compounds could be used in oxidation reactions, replacing commonly used transition metals and would be safer and more environmentally friendly reagents. The preparing of these diaryliodonium salts can be optimized since there are various possible synthesis conditions available. It was important to find optimal methods for preparing diaryliodonium salts, while avoiding the use of toxic transition metals. In the production of pseudocyclic diaryliodonium triflate salts, an acid activated pseudocyclic hypervalent iodine reagent, 2-[hydroxy(trifluoromethanesufonyloxy)]- iodobenzoic acid, can react easily with various arenes in the presence of trifluoromethanesulfonic acid. The synthesis of the pseudocyclic diaryliodonium triflate salts occurs under mild conditions to obtain the iodonium salts in moderate to good yields. Cyclic iodine (III) compounds, arylbenziodoxolones, can be produced in moderate to good yield by reacting pseudocyclic products that are formed under basic conditions. Pseudocyclic and cyclic trivalent iodonium salts can undergo synthesis, with hydroxy and carboxylic acid group compounds, producing these groups in the products and increasing reactivity in compounds obtained. Some of the pseudocyclic and cyclic diaryliodonium salts obtained have been confirmed with single crystal X-ray crystallography. These positive results lead to further investigation of taking advantage of protecting groups and phenyl boronic acid in the preparation of phenolic iodonium triflate salts. Several desired phenolic iodonium triflate salts were obtained in moderate to good yield and are reported as well.
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    Pseudocyclic benziodoxole triflate as an effective reagent for the catalytic oxidative cycloadditions of aldoximes with nitriles and maleimides
    (2017-06) Chau Nguyen, Khiem
    A novel hypervalent iodine(III) compound - pseudocyclic benziodoxole triflate (IBAOTf) - was prepared, isolated, identified and tested for its reactivity over various reactions in our previous research. Based on these preliminary results, we investigated the catalytic activity of the in situ generated IBA-OTf in cycloaddition reactions of numerous aldoximes with acetonitrile and maleimide to form 1,2,4-oxadiazoles and pyrrolo-isoxazoles, respectively. The presence of the in situ IBA-OTf species was confirmed by HR-ESI-MS and 1H NMR studies. By the reaction with IBA-OTf, the starting aldoximes were converted into the corresponding unstable nitrile oxides which were the active species reacting with acetonitrile or maleimide to form the corresponding heterocyclic five-membered ring products. Totally, nineteen 1,2,4-oxadiazoles and thirteen pyrrolo-isoxazoles have been successfully synthesized and their structures were authenticated by 1H and 13C NMR. X-ray single crystal diffraction was also performed for a typical pyrrolo-isoxazole to confirm the bicyclic structure of the products.