The reactions of 3 hydroxy and 5,7 dihydroxyflavones with hexaethylphosphorous triamide proceed according to a classical scheme, but the reaction of 5,7 dihydroxyflavone occurs regioselectively. Dismutation of phosphites, which has been studied earlier only for the sim plest aryl systems, is extended to flavonoids.
Previously we initiated research into phosphorylation of the well-known flavonoid, dihydroquercetin I, with trivalent phosphorus reagents [1,2]. Now we report about the possibility of extending this reaction on quercetin II, a compound that has a more complex structure than flavonoid I.The partially protected quercetin derivatives, viz. quercetin 3,3`,4`,7-tetrabenzylate (III) and 3,3`,4`,7-tetraacetate (IV) contain a free hydroxy group in the C 5 position [3, 4]. Phosphorylation was carried out with 2-chloro-and 2-amido-4,4-dimethyl-1,3,2-dioxaphosphorinanes. The best yields of the target products were achieved when acid chlorides were used. 58 d go E d ; 6 d j R
2005
Benzopyran derivatives R 0350Phosphorylation of 3-Hydroxy-and 5,7-Dihydroxyflavones with Hexaethylphosphorous Triamide. -The phosphorylation of flavonoids (I) and (V) with P(NEt2)3 proceeds readily even at room temperature leading to the diamidophosphites (III) and (VI), resp., which are converted to the corresponding thionophosphates (IV) and (VII).In the case of 5,7-dihydroxyflavone (V), the phosphorylation takes place regioselectively at the 7-O atom. -(DUDAKOVA*, T. V.; KOROTEEV, M. P.; LYSSENKO, K. A.; ANTIPIN, M. Y.; NIFANT'EV, E. E.; Russ.
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