ISSN:
1434-193X
Keywords:
C-Glycosyl compounds
;
Flavones
;
Flavanones
;
O-Glycosyl trichloroacetimidates
;
Fries rearrangement
;
Carbohydrates
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Glycosylation of the visnagin cleavage product 2 with O-acetyl-protected glycosyl donor 5a afforded O-glycoside 6a, which could be transformed into the O-benzyl-protected compound 6b. The latter underwent Fries-type rearrangement to afford C-glycoside 4b. The same product could be obtained directly from 2 and O-benzyl-protected glycosyl donor 5b. Reaction of 4b with benzaldehyde and anisaldehyde furnished chalcones 7A,B, which, upon treatment with base, furnished flavanone C-glycosides 10A,B. Selenium dioxide oxidation of 10A,B or of 7A,B led to the corresponding flavone C-glycosides 11A,B. The same result was obtained by Baker-Venkataraman rearrangement; on treatment with base, the O-aroyl compounds 12A-C gave C-aroyl compounds 13A-C, which, on addition of TMSOTf, furnished flavone C-glycosides 11A-C. Hydrogenolytic O-debenzylation of 11A afforded target molecule 3A, which was transformed into O-acetyl derivative 14A for characterization. Structural assignments of all compounds were based on 1H-NMR data.
Type of Medium:
Electronic Resource
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