Aerobic oxidation serves as an attractive synthetic method both economically and environmentally, since it avoids the use of stoichiometric oxidizing agents. However, activation of atmospheric oxygen poses a major thermodynamic challenge for many aerobic oxidation reactions. Herein we report the use of a tellurium containing chromophore which undergoes oxidation by self-sensitized singlet oxygen to produce a telluroxide that is capable of oxidizing a variety of substrates. Furthermore, the reduction of the telluroxide by corresponding oxidation of the substrate regenerates the reduced tellurium chromophore. Thus the tellurium chromophore can continue the redox cycle catalytically requiring only visible light and atmospheric oxygen for activation. The oxidation of 9-mesityl-3,6-diaminotelluroxanthylium by singlet oxygen was examined by UV-Vis and <sup>1</sup>HNMR spectroscopy. The catalytic oxidation of various substrates was examined where the telluroxide species serves as the active oxidant. The rates of oxygen consumption from the headspace of the reactions were used to study the rates of the reactions. By utilizing kinetic data along with Density Functional Theory (DFT) calculations, we have gained insight into possible reaction intermediates. The proposed mechanism of thiol oxidation to disulfides as well as oxygen atom transfer to phosphines, to form phosphine oxides, will be presented.

Catalytic aerobic oxidation by self-sensitized tellurium containing chromophores

253rd National Meeting (2017)

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