Cyclocondensation of hydroxylamine with 1,3-bis(het)arylmonothio 1,3-diketones and 1,3-bis(het)aryl-3-(methylthio)-2-propenones: Synthesis of 3,5-bis(het)arylisoxazoles with complementary regioselectivity

Raghava, B. and Parameshwarappa, G. and Acharya, A. and Swaroop, T. R. and Rangappa, K. S. and Ila, H. (2014) Cyclocondensation of hydroxylamine with 1,3-bis(het)arylmonothio 1,3-diketones and 1,3-bis(het)aryl-3-(methylthio)-2-propenones: Synthesis of 3,5-bis(het)arylisoxazoles with complementary regioselectivity. European Journal of Organic Chemistry, 2014 (9). pp. 1882-1892.

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Official URL: https://doi.org/10.1002/ejoc.201301667

Abstract

Efficient routes for the regioselective synthesis of 3,5-bis(het) arylisoxazoles with complementary regioselectivity have been developed. The methods involve the cyclocondensation of hydroxylamine hydrochloride with either 1,3-bis(het)aryl-monothio-substituted 1,3-diketones 1 or with 3-methylthio-1,3-bis(het)aryl-2-propenones 2 under various reaction conditions. In the first protocol, diketones 1 were treated with hydroxylamine hydrochloride in the presence of sodium acetate/acetic acid (pH 2.2) in refluxing ethanol/benzene to give 3,5-bis(het)arylisoxazoles 5, in which the het(aryl) moiety attached to thiocarbonyl group of the monothio-substituted 1,3-diketones is installed at the 3-position. On the other hand, the reaction of hydroxylamine hydrochloride with 3-(methylthio)-1,3-bis(het)aryl-2-propenones 2 in the presence of barium hydroxide in refluxing ethanol gave 3,5-bis(het) arylisoxazoles 6 with complementary regioselectivity in high yields. A probable mechanism for the formation of regioisomeric isoxazoles 5 and 6 from precursors 1 and 2 has been suggested.

Item Type: Article
Subjects: C Chemical Science > Chemistry
Divisions: Department of > Chemistry
Depositing User: Arshiya Kousar
Date Deposited: 17 Aug 2019 10:10
Last Modified: 17 Aug 2019 10:10
URI: http://eprints.uni-mysore.ac.in/id/eprint/4447

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