• K Ranganadha Rao

      Articles written in Proceedings – Section A

    • Synthetic experiments in the benzo-pyrone series - Part VIII. Some transformations of 5-hydroxy-coumarin derivatives

      B Krishnaswamy K Ranganadha Rao T R Seshadri

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      Claisen migrations of the allyl ether of 4∶7-dimethyl-5-hydroxy-coumarin gives rise to three isomeric compounds depending upon the conditions, (I) 6-allyl-5-hydroxy-4∶7-dimethyl coumarin (high yield), (II) the corresponding chroman (high yield), and (III) 8-allyl-5-hydroxy-4∶7-dimethyl coumarin (low yield). (II) has been shown to be a chroman by comparison with the corresponding methyl coumaran obtained by authentic methods from (I). The acetate of the above coumarin undergoes Fries reaction to give the 6-acetyl compound. Claisen migrations of the allyl ether of 7-hydroxy-5-methyl-coumarin yields only the 8-allyl-derivative. The difference in the behaviour of the derivatives of 5- and 7-hydroxy coumarins and the special conditions of the chroman and coumaran ring closure ofo-allyl phenols are discussed.

    • Azo dye formation in 5-hydroxycoumarins

      S Rangaswami K Ranganadha Rao

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      The 5-hydroxycoumarins behave very similar to 7-hydroxycoumarins in regard to azo-dye formation with one and more than two molecular proportions of diazotisedp-nitraniline. The significance of these results is discussed.

      The authors desire to express their grateful thanks to Prof. T. R. Seshadri for his kind interest in this work.

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