Microwave accelerated solvent-free synthesis and antifungal evaluations of flavanones |
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Authors: | N A Shakil Manish K Singh M Sathiyendiran J Kumar |
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Institution: | 1. Division of Agricultural Chemicals , Indian Agricultural Research Institute , New Delhi, 110012, India iamshakil@gmail.com;3. Division of Agricultural Chemicals , Indian Agricultural Research Institute , New Delhi, 110012, India;4. Department of Chemistry , University of Delhi , Delhi, 110007, India;5. Department of Chemistry , University of Delhi , Delhi, 110007, India;6. Division of Agricultural Chemicals , Indian Agricultural Research Institute , New Delhi, 110012, India |
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Abstract: | Microwave irradiation of 2-hydroxy chalcones under solvent-free conditions resulted in a “green-chemistry” procedure for the preparation of flavanones in good yields, using an unmodified household microwave oven and silica as solid support. By irradiation of 2-hydroxy chalcones with trifluoroacetic acid over silica gel, 11 known flavanones were prepared in high yields. The synthesised compounds were characterised using spectroscopic techniques, namely, 1H NMR, 13C NMR and IR, and screened for their antifungal activity in vitro against Sclerotium rolfsii and Rhizoctonia solani by poisoned food technique. The compounds tested were found to be more active against R. solani, whereas against S. rolfsii, moderate activity was observed, as evident from LC50 values. The most potent compound 2-(4-fluorophenyl)-2,3-dihydrochromen-4-one (4a) had LC50 value of 12.0 mg L?1 followed by 11, 11a, 3a, 9a, 8a, 10a and 10 having LC50 values 18.21, 18.3, 32.9, 50.7, 88.8, 118.8 and 119.7 mg L?1, respectively. |
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Keywords: | microwave irradiation (MWI) 2-hydroxy chalcones flavanones fungicidal activity Sclerotium rolfsii Rhizoctonia solani |
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