• A new effect of hydrogen bond formation (chelation) - Part VI. Synthesis of 5-hydroxy-2′-methoxy flavanone and 5∶7-dihydroxy-2′-methoxy flavanone

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/seca/037/05/0620-0628

    • Keywords

       

      Flavone; Flavanone; Anhydrous Potassium Carbonate; Dimethyl Sulphate; Methoxy Flavone

    • Abstract

       

      For the preparation of flavanones having a 2′-methoxy group the acid method of chalkone condensation employing benzoates of hydroxy ketones is convenient. 5-Hydroxy-2′-methoxy flavanone and 5∶7-dihydroxy-2′-methoxy flavanone have thus been prepared. By demethylating the former with aluminium chloride 5∶2′-dihydroxy flavanone is obtained which undergoes only partial methylation in the 5-position even with excess of the reagent confirming that the 2′-hydroxyl is highly resistant. Synthetic 5∶7-hydroxy-2′-methoxy flavanone and its derivatives made by us and by Shinoda and Sato agree, but they do not agree in their properties with natural citronetin and its derivatives.

      5-Hydroxy-2′-methoxy flavone does not undergo isomeric change under ordinary conditions of demethylation. 5∶2′-dihydroxy flavone undergoes partial methylation smoothly in the 2′-position thus showing the existence of marked difference between flavanones and flavones.

    • Author Affiliations

       

      N Narasimhachari1 D Rajagopalan1 T R Seshadri1

      1. Department of Chemistry, Delhi University, India
    • Dates

       
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