Synthetic experiments in the benzopyrone series - Part XXV. Isomerisation of 5∶7∶8-hydroxy flavanones
Ishwar-Dass N Narasimhachari T R Seshadri
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Heating 2-hydroxy-3∶4∶6-trimethoxy-chalkone with hydrobromic acid yields instead of the expected 7-methoxy-5∶8-dihydroxy flavanone, the isomeric 7-methoxy-5∶6-dihydroxy flavanone. The same product is obtained by the partial demethylation of 2-hydroxy-4∶5∶6-trimethoxy chalkone. Attempts to prepare 5∶8-dihydroxy-7-methoxy flavanone by the reduction of the corresponding quinone again resulted in the formation of the isomeric 7-methoxy-5∶6-dihydroxy flavanone. The 5∶8-dihydroxy compound has been obtained by the partial demethylation of 5∶7∶8-trimethoxy flavanone by means of aluminium chloride in nitrobenzene solution.
Ishwar-Dass1 N Narasimhachari1 T R Seshadri1
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