Jakšić Jovana, Mitrović Aleksandra, Tokić Vujošević Zorana, Milčić Miloš, Maslak Veselin
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.
RSC Adv. 2021 Sep 2;11(47):29426-29432. doi: 10.1039/d1ra03944j. eCollection 2021 Sep 1.
In this study, β-keto esters as readily available bio-based building blocks were used to decorate the C 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 C fullerene derivatives. The mechanism of the reaction shifted from nucleophilic aliphatic substitution to oxidative [3 + 2] cycloaddition fullerenyl cations as an intermediate. This mechanism is proposed based on a series of control experiments with radical scavengers. Therefore, dihydrofuran-fused C 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.
在本研究中，β-酮酯作为易于获得的生物基结构单元被用于修饰碳球。一般来说，环丙烷化富勒烯衍生物是通过标准的宾格尔-赫希（Bingel-Hirsch）方法获得的。在此，从反应混合物中省略碘并加入2,2,6,6-四甲基哌啶氧化物（TEMPO）得到了二氢呋喃稠合的碳富勒烯衍生物。反应机理从亲核脂肪族取代转变为以富勒烯基阳离子为中间体的氧化[3 + 2]环加成反应。该机理是基于一系列使用自由基清除剂的对照实验提出的。因此，以良好的产率选择性地获得了二氢呋喃稠合的碳衍生物，并基于紫外可见光谱、红外光谱、核磁共振光谱和质谱确定了它们的结构。通过循环伏安法研究了合成化合物的电化学性质。进行密度泛函理论（DFT）计算以研究亚甲基富勒烯和呋喃基富勒烯之间在稳定性、电子性质和π电子离域方面的差异。
