Selective formation of dihydrofuran fused [60] fullerene derivatives by TEMPO mediated [3 + 2] cycloaddition of medium chain β-keto esters to C60 |
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Authors: | Jovana Jaki Aleksandra Mitrovi Zorana Toki Vujoevi Milo Mil
i Veselin Maslak |
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Institution: | Department of Organic Chemistry, University of Belgrade, Faculty of Chemistry, Studentski Trg 12-16, 11158 Belgrade Serbia.; Department of Organic Chemistry, University of Belgrade, Faculty of Pharmacy, Vojvode Stepe 450, 11221 Belgrade Serbia |
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Abstract: | In this study, β-keto esters as readily available bio-based building blocks were used to decorate the C60 sphere. Generally, cyclopropanated fullerene derivatives are obtained by the standard Bingel–Hirsch procedure. Herein, omitting the iodine from the reaction mixture and adding TEMPO afforded dihydrofuran fused C60 fullerene derivatives. The mechanism of the reaction shifted from nucleophilic aliphatic substitution to oxidative 3 + 2] cycloaddition via fullerenyl cations as an intermediate. This mechanism is proposed based on a series of control experiments with radical scavengers. Therefore, dihydrofuran-fused C60 derivatives were selectively obtained in good yields and their structures were established based on UV-Vis, IR, NMR spectroscopy and mass spectrometry. The electrochemical properties of the synthesized compounds were investigated by cyclic voltammetry. DFT calculations were performed in order to investigate the difference in stability, electronic properties and π-electron delocalization between methano and furano fullerenes.In this study, β-keto esters as readily available bio-based building blocks were used to decorate the C60 sphere. |
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