Browsing by Author "M.Ndegwa John"

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    Chemical Transformations of Some Kniphofia Quinones
    (Addis Ababa Universty, 1994-06) M.Ndegwa John; Dagne Ermias (PhD)
    Chemical investigation of the rhizome of Kniphofia fotiosa (Hochst), Asphodelaceae, led to the isolation of a minor product code named KKA-1 (40) . The spectral data suggested that it was a dimer of knipholone (32) and its anthrone (33) . This was further confirmed by reductive cleavage to 4,6- dihydroxy-2- methoxyacetophenone (37), acetylphlorogtucinol (36) , and chrysophanol (5) . It was synthesized from knipholone anthrone (33) through oxidative coupling reactions. The synthesis of 4,6-dihydroxy-2- methoxyacetophenone (37), a consitiuent of AT. fotiosa, is reported. Knipholone (32) was synthesized from knipholone anthrone ( 33) through oxidation. Reductive cleavage of knipholone (32) gave chrysophanol (5), 4,6- dihydroxy-2- methoxyacetophenone (37 ) and acetylphloroglucinol (36) . Bromination of knipholone anthrone (33) resulted in four bromides: 41, 42, 43 and 45 . These bromides were not stable in solution