A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles

A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles

A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found to be the...

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Main Authors: Phuong Hoang Tran, Hai Ngoc Tran, Poul Erik Hansen, Mai Hoang Ngoc Do, Thach Ngoc Le
Format: Article
Language:English
Published: MDPI AG 2015-10-01
Series:Molecules
Subjects:
Friedel-Crafts acylation
indole derivatives
ionic liquids
metal triflate
microwave irradiation
Online Access:http://www.mdpi.com/1420-3049/20/10/19605
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spelling doaj-d79000b924e54fabb93206a2bc855ddc2020-11-24T23:57:04ZengMDPI AGMolecules1420-30492015-10-012010196051961910.3390/molecules201019605molecules201019605A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected IndolesPhuong Hoang Tran0Hai Ngoc Tran1Poul Erik Hansen2Mai Hoang Ngoc Do3Thach Ngoc Le4Department of Organic Chemistry, Faculty of Chemistry, University of Science, Vietnam National University, Ho Chi Minh City 70000, VietnamDepartment of Organic Chemistry, Faculty of Chemistry, University of Science, Vietnam National University, Ho Chi Minh City 70000, VietnamDepartment of Science, Systems and Models, Roskilde University, POB 260, Roskilde DK-4000, DenmarkDepartment of Organic Chemistry, Faculty of Chemistry, University of Science, Vietnam National University, Ho Chi Minh City 70000, VietnamDepartment of Organic Chemistry, Faculty of Chemistry, University of Science, Vietnam National University, Ho Chi Minh City 70000, VietnamA fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found to be the best catalyst together with the commercially available ionic liquid [BMI]BF4 (1-butyl-3-methylimidazolium tetrafluoro-borate) as solvent. The reaction is completed in a very short time using monomode microwave irradiation. The catalyst can be reused up to four times without significant loss of activity. A range of substituted indoles are investigated as substrates, and thirteen new compounds have been synthesized.http://www.mdpi.com/1420-3049/20/10/19605Friedel-Crafts acylationindole derivativesionic liquidsmetal triflatemicrowave irradiation
collection DOAJ
language English
format Article
sources DOAJ
author Phuong Hoang Tran
Hai Ngoc Tran
Poul Erik Hansen
Mai Hoang Ngoc Do
Thach Ngoc Le
spellingShingle Phuong Hoang Tran
Hai Ngoc Tran
Poul Erik Hansen
Mai Hoang Ngoc Do
Thach Ngoc Le
A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles
Molecules
Friedel-Crafts acylation
indole derivatives
ionic liquids
metal triflate
microwave irradiation
author_facet Phuong Hoang Tran
Hai Ngoc Tran
Poul Erik Hansen
Mai Hoang Ngoc Do
Thach Ngoc Le
author_sort Phuong Hoang Tran
title A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles
title_short A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles
title_full A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles
title_fullStr A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles
title_full_unstemmed A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles
title_sort simple, effective, green method for the regioselective 3-acylation of unprotected indoles
publisher MDPI AG
series Molecules
issn 1420-3049
publishDate 2015-10-01
description A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found to be the best catalyst together with the commercially available ionic liquid [BMI]BF4 (1-butyl-3-methylimidazolium tetrafluoro-borate) as solvent. The reaction is completed in a very short time using monomode microwave irradiation. The catalyst can be reused up to four times without significant loss of activity. A range of substituted indoles are investigated as substrates, and thirteen new compounds have been synthesized.
topic Friedel-Crafts acylation
indole derivatives
ionic liquids
metal triflate
microwave irradiation
url http://www.mdpi.com/1420-3049/20/10/19605
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