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Updated: Sep 14, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Unveiling Palladium Catalysis to Access Oxepino-indole through Sequential Oxycyclization Utilizing η3-π-Allyl
Puja Singh1, Manoj V Mane2, Sudeo K Mahto1
1Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India.
None:
We report a palladium-catalyzed sequential oxycyclization of indole-tethered allene to construct oxepino indole cores with yields up to 91%. This method showcases the C2 umpolung activation of indoles via η3-π-allyl reactivity and enables efficient synthesis without side products. Furthermore, extensive mechanistic investigations, encompassing control experiments, X-ray crystallographic studies, and DFT analysis, have been conducted to elucidate the underlying mechanisms. Additionally, gram-scale synthesis and product diversification have been performed to illustrate the synthetic utility of this transformation.
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