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Iridium-Catalyzed Enantioselective Intermolecular Indole C2-Allylation.

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 ?-? stacking interactions have been identified as major contributors to the C2-selectivity.

SUBMITTER: Rossi-Ashton JA

PROVIDER: S-EPMC7217203 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Iridium-Catalyzed Enantioselective Intermolecular Indole C2-Allylation.

Rossi-Ashton James A JA Clarke Aimee K AK Donald James R JR Zheng Chao C Taylor Richard J K RJK Unsworth William P WP You Shu-Li SL

Angewandte Chemie (International ed. in English) 20200311 19

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<sub>4</sub> )<sub>2</sub> 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 ...[more]

PMID: 32091146

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