Synthesis of New Functionalized Indoles Based on Ethyl Indol-2-carboxylate

Ahmed T A Boraei; El Sayed H El Ashry; Assem Barakat; Hazem A Ghabbour

doi:10.3390/molecules21030333

Synthesis of New Functionalized Indoles Based on Ethyl Indol-2-carboxylate

Molecules. 2016 Mar 10;21(3):333. doi: 10.3390/molecules21030333.

Authors

Ahmed T A Boraei¹, El Sayed H El Ashry², Assem Barakat^{3

4}, Hazem A Ghabbour^{5

6}

Affiliations

¹ Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt. ahmed_tawfeek83@yahoo.com.
² Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426, Ibrahimia, Alexandria 21321, Egypt. eelashry60@hotmail.com.
³ Chemistry Department, College of Science, King Saud University, P. O. BOX 2455, Riyadh 11451, Saudi Arabia. ambarakat@ksu.edu.sa.
⁴ Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426, Ibrahimia, Alexandria 21321, Egypt. ambarakat@ksu.edu.sa.
⁵ Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P. O. Box 2457, Riyadh 11451, Saudi Arabia. ghabbourh@yahoo.com.
⁶ Department of Medicinal Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt. ghabbourh@yahoo.com.

Abstract

Successful alkylations of the nitrogen of ethyl indol-2-carboxylate were carried out using aq. KOH in acetone. The respective N-alkylated acids could be obtained without separating the N-alkylated esters by increasing the amount of KOH and water. The use of NaOMe in methanol led to transesterification instead of the alkylation, while the use of NaOEt led to low yields of the N-alkylated acids. Hydrazinolysis of the ester gave indol-2-carbohydrazide which then was allowed to react with different aromatic aldehydes and ketones in ethanol catalyzed by acetic acid. Indol-2-thiosemicarbazide was used in a heterocyclization reaction to form thiazoles. The new structures were confirmed using NMR, mass spectrometry and X-ray single crystal analysis.

Keywords: alkylation; ethyl indol-2-carboxylate; hydrazinolysis; single-crystal X-ray diffraction.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aldehydes / chemistry
Alkylation
Carboxylic Acids / chemistry*
Esters / chemistry
Hydrolysis
Indoles / chemical synthesis*
Indoles / chemistry
Ketones / chemistry
Magnetic Resonance Spectroscopy
Molecular Structure
X-Ray Diffraction

Substances

Aldehydes
Carboxylic Acids
Esters
Indoles
Ketones