Reaction of isatins with 6-amino uracils and isoxazoles: isatin ring-opening vs. annulations and regioselective synthesis of isoxazole fused quinoline scaffolds in water

A green and efficient straightforward approach for the regioselective synthesis of novel 6-amino-5-(3-phenylisoxazolo[5,4-b] quinolin-4-yl) pyrimidine-2,4(1H, 3H)-diones and 3-methyl-1-phenyl-4-(3-phenylisoxazolo[5,4-b]quinolin-4-yl)-1H-pyrazol-5-amines via the cleavage of the isatin C-N bond follow...

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Published inGreen chemistry : an international journal and green chemistry resource : GC Vol. 17; no. 6; pp. 3362 - 3372
Main Authors Poomathi, Nataraj, Mayakrishnan, Sivakalai, Muralidharan, Doraiswamy, Srinivasan, Rajagopal, Perumal, Paramasivan T.
Format Journal Article
LanguageEnglish
Published CAMBRIDGE Royal Soc Chemistry 01.01.2015
Subjects
Chemistry
Chemistry, Multidisciplinary
Green & Sustainable Science & Technology
Physical Sciences
Science & Technology
Science & Technology - Other Topics
DESIGN
DOMINO REACTIONS
HETEROCYCLES
ANTIMICROBIAL ACTIVITIES
QUINAZOLINE
BIOLOGICAL EVALUATION
MEFLOQUINE
EFFICIENT ONE-POT
DERIVATIVES
N,S-KETENE ACETAL
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Summary:A green and efficient straightforward approach for the regioselective synthesis of novel 6-amino-5-(3-phenylisoxazolo[5,4-b] quinolin-4-yl) pyrimidine-2,4(1H, 3H)-diones and 3-methyl-1-phenyl-4-(3-phenylisoxazolo[5,4-b]quinolin-4-yl)-1H-pyrazol-5-amines via the cleavage of the isatin C-N bond followed by a ring expansion reaction in a one-pot manner has been established using environmentally benevolent p-toluene sulphonic acid as a catalyst. An exciting feature of this article is the reaction mechanism that depends on the nature of the group attached to the isatin ring nitrogen atom. The main advantages of this protocol include a short reaction time, an excellent yield, easy work-up, practical simplicity, high regioselectivity and the absence of extraction and chromatographic purification steps.
ISSN:1463-9262
1463-9270
DOI:10.1039/c5gc00006h