5.7- Dihydroxy-2-methyl chromone

Chromone, 2,3-dichloro-7-methoxy-synthesis, 3, 825 Chromone, dihydromass spectra, 2, 23 Chromone, 3,5-dihydroxy-2-methyl-selective methylation, 3, 716 Chromone, 5,7-dihydroxy-2-methyl-prenylation, 3, 716 Chromone, 3,7-dimethoxy-2-methyl-reactions... 

D-Xylose and D-arabinose have been treated with a 0.5 M acetate buffer (pH 4.5) at reflux. Besides 2-furaldehyde, some catechols and unique chromones were isolated from the reaction mixture in small proportions. These included 3,8-dihydroxy-2-methylchromone and its precursor, 5,6,7,8-tetrahydro-3,5-dihydroxy-2-methyl-8-oxochromone. A trihydroxy-2-methylchromone was also isolated from the D-xylose reac-... 

The formation of such chromones as 3,8-dihydroxy-2-methyl-chromone by treating uronic acids or pentoses with dilute acid was reported by Aso,119 and studied by Popoff and Theander,120 who obtained a number of these compounds in 3.5% yield, as well as some catechols. Although nothing is yet known about the mechanism of formation of these compounds, the fact that the chromones contain 10 carbon atoms and are produced both from pentoses and uronic acids suggests that they may be derived from 2-furaldehyde or re-ductic acid, or produced from a decarboxylated intermediate. 

Dimethoxycarbonyl- E6a, 152 (2-1 - 5-COOR — furan/Cu) Chromon 5,7-Dihydroxy-6-formyl-8-methoxy-2-methyl- E3, 106 (H - CHO)... 

PCS-catalyzed condensation of five molecules of malonyl-CoA to produce 5,7-dihydroxy-2-methyl chromone new to this plant (40). Another novel Aloe arborescens type III PKS that produces two hitherto unknown aromatic octaketides, SEK4 and SEK4b, has recently been reported (41). The application of plant cell cultures for the production of the polyketide hypericin from St. John s wort (Hypericum performatum, Hypericaceae) has been investigated (42). 

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