Ren Xiaoxiao, Gao Xing, Min Qiao-Qiao, Zhang Shu, Zhang Xingang
Green Catalysis Center, and College of Chemistry, Zhengzhou University Zhengzhou 450001 P. R. China.
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
Chem Sci. 2022 Mar 2;13(12):3454-3460. doi: 10.1039/d1sc07061d. eCollection 2022 Mar 24.
Difluoroalkylated compounds have important applications in pharmaceutical, agrochemical, and materials science. However, efficient methods to construct the alkylCF-alkyl bond are very limited, and the site-selective introduction of a difluoromethylene (CF) group into an aliphatic chain at the desired position remains challenging. Here, we report an unprecedented example of alkylzirconocene promoted difluoroalkylation of alkyl- and silyl-alkenes with a variety of unactivated difluoroalkyl iodides and bromides under the irradiation of visible light without a catalyst. The resulting difluoroalkylated compounds can serve as versatile synthons in organic synthesis. The reaction can also be applied to activated difluoroalkyl, trifluoromethyl, perfluoroalkyl, monofluoroalkyl, and nonfluorinated alkyl halides, providing a general method to controllably access fluorinated compounds. Preliminary mechanistic studies reveal that a single electron transfer (SET) pathway induced by a Zr(iii) species is involved in the reaction, in which the Zr(iii) species is generated by the photolysis of alkylzirconocene with blue light.
二氟烷基化化合物在制药、农用化学品和材料科学领域有着重要应用。然而，构建烷基-CF-烷基键的有效方法非常有限，在脂肪族链中所需位置上进行二氟亚甲基（CF）基团的位点选择性引入仍然具有挑战性。在此，我们报道了一个前所未有的例子，即在无催化剂的可见光照射下，烷基锆茂促进烷基烯烃和硅烷基烯烃与多种未活化的二氟烷基碘化物和溴化物发生二氟烷基化反应。所得的二氟烷基化化合物可作为有机合成中的通用合成子。该反应也可应用于活化二氟烷基、三氟甲基、全氟烷基、单氟烷基和非氟化烷基卤化物，并提供了一种可控地获得氟化化合物的通用方法。初步机理研究表明，反应涉及由Zr(III)物种诱导引发的单电子转移（SET）途径，其中Zr(III)物种是由烷基锆茂在蓝光下光解产生的。
