硼氮杂薁基[4]螺烯的设计合成及性质研究  

Design, Synthesis and Properties of Azulene-Based BN-[4]Helicenes

作　　者：段超 张建伟 向焌钧 杨笑迪 高希珂[1] Duan Chao;Zhang Jianwei;Xiang Junjun;Yang Xiaodi;Gao Xike(Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules,Shanghai Institute of Organic Chemistry,University of Chinese Academy of Sciences,Chinese Academy of Sciences,Shanghai 200032,China;Innovation Research Institute of Traditional Chinese Medicine,Shanghai University of Traditional Chinese Medicine,Shanghai 201203,China)

机构地区：[1]中国科学院大学,中国科学院上海有机化学研究所,中国科学院有机功能分子合成与组装化学重点实验室,上海200032 [2]上海中医药大学创新中药研究院,上海201203

出　　处：《化学学报》2022年第1期29-36,共8页Acta Chimica Sinica

基　　金：国家自然科学基金(Nos.21790362,22075310);上海市科学技术委员会项目(Nos.19XD1424700,18JC1410600)资助。

摘　　要：本工作设计合成了分别含有B—N键和C=C键的薁基[4]螺烯类分子1a/1b和2,其中B—N键和C=C键互为等电子体.紫外-可见吸收光谱、电化学循环伏安测试和理论计算结果表明B—N键可以调控共轭骨架的电子结构及芳香性.单晶结构表明1a具有螺旋几何构型,晶体中存在P和M两种对映异构体. B—N键具有部分双键性质,硼氮六元环具有一定的芳香性.大位阻基团2,4,6-三甲基苯基(Mes)使得1b在三氟乙酸(TFA)作用下不会发生类似于1a的脱硼化,而是发生和2相似的可逆质子响应, B—N键对薁单元的质子响应性质无明显影响.三配位的硼原子可以进一步和氟离子配位,使得1a对氟离子有明显的选择性响应,而1b则因大位阻的Mes取代基的存在对氟离子无明显的响应性.本工作报道了新型薁基硼氮杂螺烯及全碳螺烯分子,为薁基多环芳烃的"自下而上"合成及性质研究提供了参考.Azulene is a nonalternant and nonbenzenoid hydrocarbon with bright blue color and a dipole moment of 1.08 D,and has received increasing attention due to its unique electronic structure and physicochemical properties. Herein, we report the design and synthesis of two types of azulene-based [4]helicene 1a/1b and 2 that contain isoelectronic B—N and C=C units at the electron-rich 1-position of azulene unit, respectively. Formation of the helical scaffolds is executed by the introduction of boron and alkyne to flexible biaryl precursors, where the Lewis acidic boron and alkyne were employed as “glue”to join two subunits into fully fused scaffolds via electrophilic boronation and platinum-catalyzed cycloisomerization of alkyne at the 1-position of azulene unit, respectively. All of azulene-based helicenes were investigated by ultraviolet visible(UV-vis) absorption spectra, cyclic voltammetry(CV) measurements and density functional theory(DFT) calculations. Additionally, 1a was further characterized by single crystal structure analysis. The results suggest that the introduction of B—N unit changed the electronic structure of the conjugated aromatic framework, leading to a narrow HOMO-LUMO gap. Moreover, the B—N unit also affects the aromaticity of the π-system as revealed by nucleus-independent chemical shift(NICS) via time-dependent density functional theory(TD-DFT) calculation. The single crystal structure analysis demonstrates that 1a has a helically twisted framework and Plus(P)/Minus(M) enantiomers. However, the Gibbs activation energy(ΔG≠(T)) of the enantiomerization at room temperature is too low to separate two enantiomers by chiral high performance liquid chromatography(HPLC). Furthermore, the B—N unit exhibits partial double bond character and the BN-containing six-membered ring shows weak aromaticity. 1a with a phenyl group exhibits the deboronization upon addition of trifluoroacetic acid(TFA) as well as a specific sensing behavior to fluoride ion. However, 1b shows no deboronization upon add

关 键 词：薁 硼氮杂多环芳烃 螺烯 质子化 

分 类 号：O625.15[理学—有机化学]