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Iridium‐Catalyzed Enantioselective Intermolecular Indole C2‐Allylation
Author(s) -
RossiAshton James A.,
Clarke Aimee K.,
Donald James R.,
Zheng Chao,
Taylor Richard J. K.,
Unsworth William P.,
You ShuLi
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202001956
Subject(s) - enantioselective synthesis , chemistry , allylic rearrangement , indole test , steric effects , intermolecular force , catalysis , olefin fiber , iridium , regioselectivity , selectivity , stacking , stereochemistry , combinatorial chemistry , organic chemistry , molecule
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(ClO 4 ) 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.