C-Glycosides of Visnagin Analogues

✍ Scribed by Emad El Telbani; Sayed El Desoky; Mahmoud Ahmed Hammad; Abdel Rahman Hassan Abdel Rahman; Richard R. Schmidt

• Book ID: 101277254
• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 294 KB
• Volume: 1998
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(199811)1998:11<2317::aid-ejoc2317>3.0.co;2-i

✦ Synopsis

Glycosyl trichloroacetimidates / Fries rearrangement / Carbohydrates Glycosylation of the visnagin cleavage product 2 with O-to the corresponding flavone C-glycosides 11A,B. The same result was obtained by Baker-Venkataraman rearrangement; acetyl-protected glycosyl donor 5a afforded O-glycoside 6a, which could be transformed into the O-benzyl-protected on treatment with base, the O-aroyl compounds 12A-C gave C-aroyl compounds 13A-C, which, on addition of TMSOTf, compound 6b. The latter underwent Fries-type rearrangement to afford C-glycoside 4b. The same product could be furnished flavone C-glycosides 11A-C. Hydrogenolytic Odebenzylation of 11A afforded target molecule 3A, which obtained directly from 2 and O-benzyl-protected glycosyl donor 5b. Reaction of 4b with benzaldehyde and was transformed into O-acetyl derivative 14A for characterization. Structural assignments of all compounds anisaldehyde furnished chalcones 7A,B, which, upon treatment with base, furnished flavanone C-glycosides