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Updated: Dec 27, 2025
A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Iridium-Catalyzed Enantioselective Intermolecular Indole C2-Allylation
James A Rossi-Ashton1, Aimee K Clarke1, James R Donald1
1Department of Chemistry, University of York, York, YO10 5DD, UK.
Abstract:
The enantioselective intermolecular C2-allylation of 3-substituted indoles is reported for the first time. This directing group-free approach relies on a chiral Ir-(P, olefin) complex and Mg(ClO4 )2 Lewis acid catalyst system to promote allylic substitution, providing the C2-allylated products in typically high yields (40-99 %) and enantioselectivities (83-99 % ee) with excellent regiocontrol. Experimental studies and DFT calculations suggest that the reaction proceeds via direct C2-allylation, rather than C3-allylation followed by in situ migration. Steric congestion at the indole-C3 position and improved π-π stacking interactions have been identified as major contributors to the C2-selectivity.
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