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Synthesis of Verbascoside: A Dihydroxyphenylethyl Glycoside with Diverse Bioactivity
Author(s) -
Duynstee Howard I.,
de Koning Martijn C.,
Ovaa Huib,
van der Marel Gijs A.,
van Boom Jacques H.
Publication year - 1999
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(199910)1999:10<2623::aid-ejoc2623>3.0.co;2-k
Subject(s) - chemistry , verbascoside , disaccharide , glycoside , stereochemistry , thio , orthoester , derivative (finance) , organic chemistry , financial economics , economics
TMSOTf‐mediated condensation of ethyl 4,6‐ O ‐benzylidene‐1‐thio‐β‐ D ‐glucopyranoside ( 2 ) with peracetylated α‐ L ‐rhamnopyranosyl trichloroacetimidate donor 3a resulted in the formation of orthoester 4 , which, after acetylation, rearranged into ethyl 3‐ O ‐(α‐ L ‐rhamnopyranosyl)‐1‐thio‐β‐ D ‐glucopyranoside derivative 6a . The latter compound was converted into the corresponding trichloroacetimidate donors 8a–b . An alternative approach to trichloroacetimidate 8c commenced with the iodonium ion mediated glycosidation of ethyl 2,3,4‐tri ‐O ‐benzoyl‐1‐thio‐α‐ L ‐rhamnopyranside ( 15 ) with 1,2:5,6‐diisopropylidene‐ D ‐glucofuranose ( 16 ) to afford disaccharide 17 , which was transformed into 8c in five steps. Condensation of 8a–c with 2‐[3,4‐di‐( tert ‐butyldimethyl‐silyloxy)phenyl]ethanol ( 12 ) gave, after deacylation, key intermediate 14 . Protecting‐group manipulation of 14 and subsequent esterification of resulting 22 with 3,4‐di‐ O ‐ tert ‐butyldimethylsilylcaffeic acid ( 27 ) gave, after deprotection, verbascoside ( 1 ).