CONSTITUTION OF FLAVONE PITGULARIN - C

Constitution of a new flavone Pitgularin - C isolated from Pityrograma triangularis has been confirmed by its synthesis as 3,5-dihydroxy -7 -methoxy - 8 methylflavone (I) by two methods: First method utilised 2 '-hydroxy-3'-methyl-4', 6' dimethoxychalcone (v) as an essential intermediate. AFO oxidation of (V) gave 3-hydroxy-5 ,7-dimethoxy-8-methylflavone (II) which on selective demethylation formed 3 ,5 -dihyroxy-7-methoxy-8-methylflavone (I). Second method utilised Allan Robinson condensation of 2 -hydroxy-omega ,4,6-trimethoxy-3-methylacetophenone (VII), Benzoic anhydride and sodium benzoate to get 3,5,7-trimethoxy-8-methylflavone (III) which on demethylation followed by selective methylation gave 3 ,5 -dihyroxy-7-methoxy-8-methylflavone (I)