Regioselectivity of Larock heteroannulation: A contribution from electronic properties of diarylacetylenes

A series of 2,3-diarylindoles were synthesized from 2-iodoaniline and unsymmetrical diarylacetylenes using the Larock heteroannulation. Diarylacetylenes bearing electron-withdrawing substituents lead to 2,3-diarylindoles with substituted phenyl moieties at the 2-position as major products, while tho...

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Bibliographic Details
Main Authors: Nared Phetrak, Thanya Rukkijakan, Jakkapan Sirijaraensre, Samran Prabpai, Palangpon Kongsaeree, Chayada Klinchan, Pitak Chuawong
Other Authors: Faculty of Engineering
Format: Article
Published: 2018
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Online Access:https://repository.li.mahidol.ac.th/handle/123456789/31501
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Institution: Mahidol University
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Summary:A series of 2,3-diarylindoles were synthesized from 2-iodoaniline and unsymmetrical diarylacetylenes using the Larock heteroannulation. Diarylacetylenes bearing electron-withdrawing substituents lead to 2,3-diarylindoles with substituted phenyl moieties at the 2-position as major products, while those with electron-donating groups preferably yield indole products with substituted phenyl moieties at the 3-position. The regioisomeric product ratios exhibit a clear correlation with Hammett σp values. DFT calculations reveal the origin of this effect, displaying smaller activation energy barriers for those pathways leading to the major regioisomer. © 2013 American Chemical Society.