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Organocatalysis in heterocyclic synthesis: DABCO as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives
BACKGROUND: There are only limited publications devoted to the synthesis of especially thiazolo[3,2-a]quinazoline which involved reaction of 2-mercaptopropargyl quinazolin-4-one with various aryl iodides catalyzed by Pd-Cu or by condensation of 2-mercapto-4-oxoquinazoline with chloroacetic acid, ins...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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BioMed Central
2013
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3681655/ https://www.ncbi.nlm.nih.gov/pubmed/23651877 http://dx.doi.org/10.1186/1752-153X-7-82 |
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author | Behbehani, Haider Ibrahim, Hamada Mohamed |
author_facet | Behbehani, Haider Ibrahim, Hamada Mohamed |
author_sort | Behbehani, Haider |
collection | PubMed |
description | BACKGROUND: There are only limited publications devoted to the synthesis of especially thiazolo[3,2-a]quinazoline which involved reaction of 2-mercaptopropargyl quinazolin-4-one with various aryl iodides catalyzed by Pd-Cu or by condensation of 2-mercapto-4-oxoquinazoline with chloroacetic acid, inspite of this procedure was also reported in the literature to afford the thiazolo [2,3-b] quinazoline. So the multistep synthesis of the thiazolo[3,2-a]- quinazoline suffered from some flaws and in this study we have synthesized a novel class of thiazoloquinazolines by a simple and convenient method involving catalysis by 1,4-diazabicyclo[2.2.2]octane (DABCO). RESULTS: A new and convenient one-pot synthesis of a novel class of 2-arylidene-2H-thiazolo[3,2-a]quinazoline-1,5-diones 9a-i was established through the reaction between methyl-2-(2-thio-cyanatoacetamido)benzoate (4) and a variety of arylidene malononitriles 8a-i in the presence of DABCO as a mild and efficient catalytic system via a Michael type addition reaction and a mechanism for formation of the products observed is proposed. Moreover 4 was converted to ethyl-2-[(4-oxo-3,4-dihydroquinazolin-2-yl)thio]acetate (10) upon reflux in ethanol containing DABCO as catalyst. The latter was reacted with aromatic aldehydes and dimethylformamide dimethylacetal (DMF-DMA) to afford a mixture of two regioselectively products with identical percentage yield, these two products were identified as thiazolo[3,2-a]quinazoline 9,13 and thiazolo[2,3-b]quinazoline 11,12 derivatives respectively. The structure of the compounds prepared in this study was elucidated by different spectroscopic tools of analyses also the X-ray single crystal technique was employed in this study for structure elucidation, Z/E potential isomerism configuration determination and to determine the regioselectivity of the reactions. CONCLUSION: A simple and efficient one-pot synthesis of a novel class of 2-arylidene-2H-thiazolo[3,2-a]quinazoline-1,5-diones 9a-i was established through DABCO catalyzed Michael type addition reaction. In addition many fused quinazoline and quinazoline derivatives were synthesized which appeared as valuable precursors in synthetic and medicinal chemistry. |
format | Online Article Text |
id | pubmed-3681655 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2013 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-36816552013-06-25 Organocatalysis in heterocyclic synthesis: DABCO as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives Behbehani, Haider Ibrahim, Hamada Mohamed Chem Cent J Research Article BACKGROUND: There are only limited publications devoted to the synthesis of especially thiazolo[3,2-a]quinazoline which involved reaction of 2-mercaptopropargyl quinazolin-4-one with various aryl iodides catalyzed by Pd-Cu or by condensation of 2-mercapto-4-oxoquinazoline with chloroacetic acid, inspite of this procedure was also reported in the literature to afford the thiazolo [2,3-b] quinazoline. So the multistep synthesis of the thiazolo[3,2-a]- quinazoline suffered from some flaws and in this study we have synthesized a novel class of thiazoloquinazolines by a simple and convenient method involving catalysis by 1,4-diazabicyclo[2.2.2]octane (DABCO). RESULTS: A new and convenient one-pot synthesis of a novel class of 2-arylidene-2H-thiazolo[3,2-a]quinazoline-1,5-diones 9a-i was established through the reaction between methyl-2-(2-thio-cyanatoacetamido)benzoate (4) and a variety of arylidene malononitriles 8a-i in the presence of DABCO as a mild and efficient catalytic system via a Michael type addition reaction and a mechanism for formation of the products observed is proposed. Moreover 4 was converted to ethyl-2-[(4-oxo-3,4-dihydroquinazolin-2-yl)thio]acetate (10) upon reflux in ethanol containing DABCO as catalyst. The latter was reacted with aromatic aldehydes and dimethylformamide dimethylacetal (DMF-DMA) to afford a mixture of two regioselectively products with identical percentage yield, these two products were identified as thiazolo[3,2-a]quinazoline 9,13 and thiazolo[2,3-b]quinazoline 11,12 derivatives respectively. The structure of the compounds prepared in this study was elucidated by different spectroscopic tools of analyses also the X-ray single crystal technique was employed in this study for structure elucidation, Z/E potential isomerism configuration determination and to determine the regioselectivity of the reactions. CONCLUSION: A simple and efficient one-pot synthesis of a novel class of 2-arylidene-2H-thiazolo[3,2-a]quinazoline-1,5-diones 9a-i was established through DABCO catalyzed Michael type addition reaction. In addition many fused quinazoline and quinazoline derivatives were synthesized which appeared as valuable precursors in synthetic and medicinal chemistry. BioMed Central 2013-05-07 /pmc/articles/PMC3681655/ /pubmed/23651877 http://dx.doi.org/10.1186/1752-153X-7-82 Text en Copyright © 2013 Behbehani and Ibrahim; licensee Chemistry Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Article Behbehani, Haider Ibrahim, Hamada Mohamed Organocatalysis in heterocyclic synthesis: DABCO as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives |
title | Organocatalysis in heterocyclic synthesis: DABCO as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives |
title_full | Organocatalysis in heterocyclic synthesis: DABCO as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives |
title_fullStr | Organocatalysis in heterocyclic synthesis: DABCO as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives |
title_full_unstemmed | Organocatalysis in heterocyclic synthesis: DABCO as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives |
title_short | Organocatalysis in heterocyclic synthesis: DABCO as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives |
title_sort | organocatalysis in heterocyclic synthesis: dabco as a mild and efficient catalytic system for the synthesis of a novel class of quinazoline, thiazolo [3,2-a]quinazoline and thiazolo[2,3-b] quinazoline derivatives |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3681655/ https://www.ncbi.nlm.nih.gov/pubmed/23651877 http://dx.doi.org/10.1186/1752-153X-7-82 |
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