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- Title
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.
- Authors
Raghava, Byregowda; Parameshwarappa, Gangajji; Acharya, Anand; Swaroop, Toreshettahally R.; Rangappa, Kanchugarakoppal S.; Ila, Hiriyakkanavar
- 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.
- Subjects
ISOXAZOLES; HETEROCYCLIC compounds synthesis; REGIOSELECTIVITY (Chemistry); CONDENSATION reactions; HYDROXYLAMINE hydrochloride; KETONES; SODIUM acetate; ACETIC acid
- Publication
European Journal of Organic Chemistry, 2014, Vol 2014, Issue 9, p1882
- ISSN
1434-193X
- Publication type
Article
- DOI
10.1002/ejoc.201301667