Abstract
An efficient three component synthesis of highly functionalized 4-methyl-1H-quinolin-2-ones in one-pot from readily available coumarin, hydrazine and isatin catalyzed by a recyclable and moisture compatible InCl3 under microwave irradiation has been developed. The synthesis involves a InCl3 catalyzed dehydrative nucleophilic substitution on the lactone moiety of coumarin by the isatin hydrazone resulting in the formation of N-substituted lactams, 6substituted-4-methyl-1-(2-oxo-1,2-dihydroindol-3-ylidenamino)-1H-quinolin-2-ones. The coumarin based transformation into substituted 1H-quinolin-2-ones proceeded smoothly with quantitative yields at ambient temperature.
Highlights
The presence of a quinoline nucleus in the frame work of various pharmacologically active compounds with antiasthmatic,[1] antibacterial,[2] antifungal,[3] antimalarial,[4] antiviral,[5] antiinflammatory[6] activities continue to promote their synthetic efforts
A series of compounds derived from 8-hydroxyquinolines and styryl quinoline were recently synthesized as potential HIV-1 integrase inhibitors.[8,9]
The classical synthetic protocols for quinolin-2-one derivatives which suffer from disadvantages such as low yields, lack of easy availability/preparation of reagents, prolonged reaction time, multistep procedures, harsh reaction conditions etc. has increased our interest in making an effort for the development of environmentally benign and more atom economical simple protocols for the synthesis of 1Hquinolin-2-one derivatives
Summary
The presence of a quinoline nucleus in the frame work of various pharmacologically active compounds with antiasthmatic,[1] antibacterial,[2] antifungal,[3] antimalarial,[4] antiviral,[5] antiinflammatory[6] activities continue to promote their synthetic efforts. Recent years have witnessed a phenomenal growth in the application of microwave activation in organic synthesis.[20] The application of microwave activation in conjugation with metal halide catalysts in one-pot multi-component reactions provides an environmentally benign process associated with higher yield of products, mild reaction conditions, a significant reduction in reaction time, an enhanced reaction rate, all of which are additional eco-friendly attributes in the context of green chemistry.[21]. As part of our program to develop new, simple, efficient, clean, selective, environmentally benign methodologies for the synthesis of potential bioactive heterocycles we report here the catalytic activity of InCl3 in a one-pot three-component efficient and clean synthesis of 1Hquinolin-2-one from coumarin in the presence of hydrazine[22] (Scheme 1)
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