Yang Xinhe, Su Shilong, Hu Chenyu, Cheung Ka Man, Yang Daiyue, Chen Xiao, Yang Jun, Huang Zhifeng, Kwong Fuk Yee, Miao Qian
State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007, China.
Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 230032, China.
Angew Chem Int Ed Engl. 2025 May;64(21):e202501169. doi: 10.1002/anie.202501169. Epub 2025 Mar 18.
This study explores two structurally related π-skeletons. The π-skeleton of compounds 1a-e containing three heptagons represents a key fragment in theoretical carbon schwarzites, while that of 2a-b is a triple [6]helicene. Compounds 1a-e were synthesized via Scholl reactions, and using a weaker acid allowed the reaction to stop at an intermediate stage, yielding 2a-b. X-ray crystallography revealed not only distinct stereochemistry of 1b and 2a but also unique supramolecular assemblies in the clathrate of 2a with chloroform. Compound 1b adopts a saddle-like geometry, while 2a exhibits a propeller-like structure with C symmetry, consistent with density functional theory (DFT) calculations. The π-skeleton of 1a-e is flexible, enabling rapid enantiomerization, whereas that of 2a-b is rigid, allowing resolution of 2b into optically pure forms with an absorption dissymmetry factor as high as 0.015. Comparative analysis shows that presence of seven-membered rings in 1a-e does not significantly alter the local aromaticity of the triple [6]helicene framework.
本研究探索了两种结构相关的π-骨架。化合物1a-e的π-骨架包含三个七元环，是理论上碳方钠石中的关键片段，而化合物2a-b的π-骨架是一个三联[6]螺旋烯。化合物1a-e通过肖尔反应合成，使用较弱的酸可使反应在中间阶段停止，生成2a-b。X射线晶体学不仅揭示了1b和2a独特的立体化学，还揭示了2a与氯仿包合物中独特的超分子组装。化合物1b采用鞍状几何结构，而2a呈现具有C对称性的螺旋桨状结构，这与密度泛函理论（DFT）计算结果一致。1a-e的π-骨架具有柔性，能够快速对映异构化，而2a-b的π-骨架是刚性的，可将2b拆分为光学纯形式，吸收不对称因子高达0.015。对比分析表明，1a-e中七元环的存在不会显著改变三联[6]螺旋烯骨架的局部芳香性。
