Chemistry Department, M.V. Lomonosov Moscow State University, Leninskie Gory, 1-3, 119991, Moscow, Russia.
Endocrinology Research Centre, 12 Dm.Ul'yanova, str., 117036, Moscow, Russia.
Chem Asian J. 2020 Jun 2;15(11):1701-1708. doi: 10.1002/asia.202000320. Epub 2020 Apr 30.
Alkylation of homofullerene [6,6]-C (CF ) dianion with the set of alkyl halides, RX, was established to demonstrate an effect of RX nature on the conversion, product composition, and regioselectivity. The respective C (CF )RH, C (CF )R and C (CF )R'R'' compounds were obtained in the reaction with sterically unhindered RX, isolated by HPLC and unequivocally characterized. The kinetic studies evidenced S 2 mechanism for both alkylation steps, yielding mono- and dialkylated C (CF ), respectively, and indicated the negative charge localization at the bridgehead carbon atoms as well as a steric hindrance of the CF moiety likely to be a key factors for the S 2 reaction mechanism and observed regioselectivity. The significant difference in the rate constants of the first and the second steps is attributed to the different activation barriers predicted by DFT calculations which makes possible to develop synthetic methods for the regioselective preparation of monoalkylated C (CF )RH and heterodialkylated C (CF )R'R'' derivatives.
用一组卤代烷烃（RX）对同富勒烯[6,6]-C（CF ）二负离子进行烷基化，以证明 RX 性质对转化、产物组成和区域选择性的影响。在与空间位阻较小的 RX 的反应中得到了相应的 C（CF ）RH、C（CF ）R 和 C（CF ）R'R''化合物，通过 HPLC 分离并进行了明确的表征。动力学研究证明了两个烷基化步骤均遵循 S 2 机制，分别生成单烷基化和二烷基化的 C（CF ），并表明桥碳原子上的负电荷定位以及 CF 部分的空间位阻可能是 S 2 反应机制和观察到的区域选择性的关键因素。第一步和第二步的速率常数的显著差异归因于 DFT 计算预测的不同活化能垒，这使得有可能开发用于单烷基化 C（CF ）RH 和杂二烷基化 C（CF ）R'R''衍生物的区域选择性制备的合成方法。
