R. Palkar, H. Master
Feb 1, 2000
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Journal
ChemInform
Abstract
Reports on the chemistry of 6-aminoflavones • are limited since the commonly occurring natural flavonoids are not substituted at position-6. Also, various flavones bearing a methoxy group at position3, such as 4'-hydroxy-3-methoxyflavone and 3-0methylquercetin are known for antiviral activity•• It has been observed that substituted 3-methoxyflavones are more potent than 3-0-methylquercetin. In view of the known biological activity enhancing effect of the methoxy group at position-3 and in continuation of our studies on the synthesis of 6-aminoflavones, as possible antibacterial agents, it was thought of interest to synthesis some new title compounds. 2'-Hydroxychalcones 3a-d were prepared by the condensation of 5-acetamido-2-hydroxyacetophenone 1 and the corresponding substituted benzaldehydes 2a-d in alkaline medium. These chalcones were cyclised to 6-acetamido-3-hydroxyflavones 4a-d by the action of alkaline hydrogen peroxide (Algar, Flynn, Oyamada oxidation)•• Compounds 4a-d on refluxing in acetone with anhydrous potassium carbonate and dimethyl sulfate afforded 3methoxyflavones Sa-d. Acid hydrolysis of Sa-d gave the title compounds 6-amino-3-methoxyflavones 6ad. IR spectra of 6 showed bands at 3445-3360 (NH2) and 1620-1640 cm(C=O). The H NMR spectra exhibiting singlets at 8 5.5 and 3.8 for amino and methoxy group, respectively supported the structure of 6-amino-3-methoxyflavones.