Study on the Condensation of Different Hydroxy Aromatic Aldehydes with 2-Substituted 2-Oxazolin-5-ones Generated in situ
American Journal of Heterocyclic Chemistry
Volume 5, Issue 1, March 2019, Pages: 1-3
Received: Jan. 25, 2019;
Accepted: Mar. 14, 2019;
Published: Apr. 8, 2019
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Pubanita Bhuyan, Department of Chemistry, North Eastern Regional Institute of Science and Technology, Nirjuli, Itanagar, India
Pradeep K. Tripathy, Department of Chemistry, North Eastern Regional Institute of Science and Technology, Nirjuli, Itanagar, India
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In view to synthesize some bioactive 2-Substituted 4-(hydroxybenzylidene)-2-oxazolin-5-ones through a disciplined route, a study on the condensation of 2-, 3- and 4- hydroxy aromatic aldehydes (6) with 2-Substituted 2-oxazolin-5-ones (5) was carried out. 2-Substituted 2-oxazolin-5-ones (5) which are also known as saturated azlactones and unstable, were generated in situ from α-N-Acylglycines (1) using various cyclising agents namely ethyl chloroformate (2), benzene sulphonyl chloride (3) and p-toluene sulphonyl chloride (4) in dry benzene in presence of triethylamine base. The hydroxyl group at 3- and 4- positions of aromatic aldehydes namely 4-hydroxy-3-methoxybenzaldehyde (6a), m-hydroxybenzaldehyde (6b)and p-hydroxybenzaldehyde (6c) produce 2-substituted 4-(p-hydroxy-m-methoxybenzylidene)-2-oxazolin-5-one (8a), 2-substituted-4 (m-hydroxybenzylidene)-2-oxazolin-5-one (8b) and2-substituted-4 (p-hydroxybenzylidene)-2-oxazolin-5-one (8c) respectively as their (Z)-isomers, whereas 2-hydroxy aromatic aldehyde namely salicylaldehydeproduces 3-N-acylaminocoumarins (9) on condensation with 2-Substituted 2-oxazolin-5-ones (5) in appreciable yields and good purity. The reaction seems to be initiated by the formation of an adduct (E)-2-substituted 4-(o-hydroxybenzylidene-2-oxazolin-5-ones (7), followed by intramolecular 1,5- bond cleavage of the 2-oxazolin-5-one ring by the vicinal phenolic group and subsequent recyclization led to the formation of resultant 3-N-acylaminocoumarins (9). It is noteworthy that free hydroxyl group bearing benzylidene moiety at 4-position of 2-oxazolin-5-ones (8) were obtained. All the steps can be carried out in one flask.
4-(Hydroxybenzylidene) Azlactones, 3-N-Acylaminocoumarins, Cyclisingagents, Synthons, in situ
To cite this article
Pradeep K. Tripathy,
Study on the Condensation of Different Hydroxy Aromatic Aldehydes with 2-Substituted 2-Oxazolin-5-ones Generated in situ, American Journal of Heterocyclic Chemistry.
Vol. 5, No. 1,
2019, pp. 1-3.
Copyright © 2019 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/
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