Synthesis and chiroptical characterization of a negatively curved helicene with a central tropone unit
We report the synthesis of an π-expanded [5]helicene incorporating a seven-membered tropone unit. The synthesis was based on a cycloaddition-cyclization strategy that exploited the versatile reactivity of alkynes. X-ray crystallographic analysis of the racemic compound revealed its highly twisted st...
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| Main Authors: | , , , , , |
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| Format: | Article (Journal) Editorial |
| Language: | English |
| Published: |
November 07, 2025
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| In: |
Synlett
Year: 2026, Volume: 37, Issue: 02, Pages: 232-236 |
| ISSN: | 1437-2096 |
| DOI: | 10.1055/a-2698-2720 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1055/a-2698-2720 Verlag, lizenzpflichtig, Volltext: http://www.thieme-connect.de/DOI/DOI?10.1055/a-2698-2720 
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| Author Notes: | Wolfgang Kies, Erik Misselwitz, Jan Borstelmann, Georg Berger, Frank Rominger, Milan Kivala |
| Summary: | We report the synthesis of an π-expanded [5]helicene incorporating a seven-membered tropone unit. The synthesis was based on a cycloaddition-cyclization strategy that exploited the versatile reactivity of alkynes. X-ray crystallographic analysis of the racemic compound revealed its highly twisted structure and provided insights into the structural impacts of the tropone moiety on the [5]helicene subunit. Enantiomeric resolution by chiral HPLC followed by an assessment of the configurational stability revealed a significantly reduced barrier for racemization compared to pristine [5]helicene. Density functional theory calculations on the racemization mechanism identified the crucial role of the flexible tropone unit in preorganizing the molecular framework toward the transition-state geometry, thereby lowering the activation barrier. |
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| Item Description: | Gesehen am 23.02.2026 |
| Physical Description: | Online Resource |
| ISSN: | 1437-2096 |
| DOI: | 10.1055/a-2698-2720 |