Huo Gui-Fei, Fukunaga Toshiya M, Hou Xudong, Han Yi, Fan Wei, Wu Shaofei, Isobe Hiroyuki, Wu Jishan
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Department of Chemistry, The University of Tokyo Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Angew Chem Int Ed Engl. 2023 Apr 24;62(18):e202218090. doi: 10.1002/anie.202218090. Epub 2023 Mar 22.
Expanded helicenes are expected to show enhanced chiroptical properties as compared to the classical helicenes but the synthesis is very challenging. Herein, we report the facile synthesis of a series of expanded helicenes Hn (n=1-4) containing 11, 19, 27 and 35 cata-fused benzene rings through Suzuki coupling-based oligomerization followed by Bi(OTf) -mediated regioselective cyclization of vinyl ethers. Their structures were determined by X-ray crystallographic analysis. Enantiopure H2, H3, and H4 can be isolated by chiral HPLC and they all exhibit strong chiroptical responses with high absorption dissymmetry factor (|g |) values (0.020 for H2, 0.021 for H3, and 0.021-0.024 for H4).
与传统的螺旋烯相比，扩展螺旋烯有望展现出增强的手性光学性质，但合成过程极具挑战性。在此，我们报道了通过基于铃木偶联的低聚反应，随后进行Bi(OTf)介导的乙烯基醚区域选择性环化反应，简便地合成了一系列含有11、19、27和35个并苯环的扩展螺旋烯Hn（n = 1 - 4）。它们的结构通过X射线晶体学分析确定。对映体纯的H2、H3和H4可通过手性高效液相色谱分离，并且它们都表现出强烈的手性光学响应，具有高吸收不对称因子（|g|）值（H2为0.020，H3为0.021，H4为0.021 - 0.024）。
