ISSN:
0947-3440
Keywords:
Glycosides
;
Flavones
;
Vitexin
;
Isovitexin
;
Isoembigenin
;
Carbohydrates
;
Trichloroacetimidates
;
Fries rearrangement
;
Baker-Venkataraman rearrangement
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
2-Hydroxy-4,6-dimethoxyacetophenone (4) was glycosylated with O-(2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl) trichloroacetimidate (5) and trimethylsilyl triflate as promoter to yield directly the C-glycoside 6. Construction of the flavone system by application of a Baker-Venkataraman-type rearrangement followed by deprotection yielded isoembigenin (2). Glycosylation of 4,6-bis(tert-butyldimethylsilyloxy)-2-hydroxyacetophenone (17) with the trichloroacetimidate 5 afforded the O-glycoside intermediate 18 which was converted via Fries rearrangement into the C-glycoside 21. Applying again the Baker-Venkataraman rearrangement and cyclization gave isovitexin and vitexin derivatives 25 and 26, which were completely deprotected to yield isovitexin (1b) and vitexin (1a), respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199519950362
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