Strain‐Sequenced Synthesis of a Quadruply Twisted Cycloarene With Alternating [4]/[5]Helicenes
-catalyzed, eightfold alkyne benzannulation. Mechanistic studies reveal that the high intrinsic energy of the alkyne-containing precursor drives a key C─C σ-bond rearrangement through a spiro-five-membered-ring intermediate to deliver An4 with quadruple helical twists. X-ray crystallography confirms the parallelogram geometry, featuring a well-defined central cavity with distinct 'Cove' and 'Fjord' regions. Bond-length analysis, complemented by theoretical calculations, revealed that both the modeling compound AnM and An4 undergo adaptive π-electron redistribution to maximize the number of aromatic sextets, resulting in stable and locally aromatic ground states consistent with Clar's rule. The electronic structure is dominated by local aromaticity, with negligible global delocalization. This study not only introduces a versatile synthetic strategy for topological nanocarbons with multiple helical twists, but also provides fundamental insights into the interplay between strain, reactivity, and aromaticity in contorted π-systems.
Authors
- Yuguang Sui
- Zebing Zeng (ORCID: https://orcid.org/0000-0002-6246-3911)
- Jiahang Hao
- Shuguang Wang (ORCID: https://orcid.org/0000-0002-7706-0621)
- Yong Ni
- Cihui Lin
Institutions
- Hunan University (CN)
- Southern University of Science and Technology (CN)
Publication Details
- Journal
- Angewandte Chemie International Edition
- Published
- 2026-04-11
- DOI
- https://doi.org/10.1002/anie.9120632
- Primary Topic
- Synthesis and Properties of Aromatic Compounds
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Guangdong Innovative and Entrepreneurial Research Team Program
- National Natural Science Foundation of China