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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Main Authors: | , , , , , , |
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Other Authors: | |
Format: | Article |
Published: |
2018
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Subjects: | |
Online Access: | https://repository.li.mahidol.ac.th/handle/123456789/31501 |
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Institution: | Mahidol University |
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. |
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