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C‐Glycosides of Visnagin Analogues
Author(s) -
El Telbani Emad,
El Desoky Sayed,
Hammad Mahmoud Ahmed,
Abdel Rahman Abdel Rahman Hassan,
Schmidt Richard R.
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199811)1998:11<2317::aid-ejoc2317>3.0.co;2-i
Subject(s) - chemistry , glycoside , glycosyl , stereochemistry , glycosylation , benzaldehyde , aldose , derivative (finance) , organic chemistry , catalysis , biochemistry , financial economics , economics
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 1 H‐NMR data.