• K R Laumas

      Articles written in Proceedings – Section A

    • A synthesis of stillopsidin and its methyl ethers

      K R Laumas S Neelakantan T R Seshadri

      More Details Abstract Fulltext PDF

      On the consideration that stillopsidin is 5-hydroxybutein, butein trimethyl ether has been subjected to nuclear oxidation and final methylation to yield stillopsidin tetramethyl ether. Stillopsidin has now been prepared in better yields by an improved method. The product obtained by the partial demethylation of 2: 4: 5-trimethoxyacetophenone is shown to be 2: 5-dihydroxy-4-methoxyacetophenone which has been prepared by an unequivocal method from pæonol. Similarly an authentic sample of 2: 5-dihydroxy-4-methoxy-benzophenone has been prepared and shown to be the same as that obtained by the partial demethylation of 2: 4: 5-trimethoxybenzophenone. A synthesis of 2:4-dihydroxy-5-methoxyacetophenone has also been carried out.

    • Leucoanthocyanidin-(flav-3-ene-3-ol) acetates

      K R Laumas T R Seshadri

      More Details Abstract Fulltext PDF

      Leucodelphinidin (flavan-diol, I B) under mild conditions of acetylation and another leucodelphinidin (flavan-diol, I A) under more drastic conditions yield the same flav-3-ene-3-ol acetate which produces delphinidin chloride in much better yields than the original diols. Products of reductive acetylation of flavonols agree with flav-3-ene-3-ol acetates in important respects. Reductive acetylation of dihydro-quercetin yields the same product as that of quercetin. Quercetin pentamethyl ether suffers similar reduction under the same conditions. It is therefore concluded that reductive acetylation reduces both the ethylenic and carbonyl groups and is followed by loss of the elements of water.

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