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Sequential Dy(OTf) 3 ‐Catalyzed Solvent‐Free Per‐ O ‐Acetylation and Regioselective Anomeric De‐ O ‐Acetylation of Carbohydrates
Author(s) -
Yan YiLing,
Guo JiunRung,
Liang ChienFu
Publication year - 2017
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201700867
Subject(s) - anomer , acetylation , regioselectivity , chemistry , acetic anhydride , catalysis , yield (engineering) , organic chemistry , trifluoromethanesulfonate , aldose , hemiacetal , solvent , glycoside , medicinal chemistry , biochemistry , materials science , metallurgy , gene
Dysprosium(III) trifluoromethanesulfonate‐catalyzed per‐ O ‐acetylation and regioselective anomeric de‐ O ‐acetylation of carbohydrates can be tuned by adjusting the reaction medium. In this study, the per‐ O ‐acetylation of unprotected sugars by using a near‐stoichiometric amount of acetic anhydride under solvent‐free conditions resulted in the exclusive formation of acetylated saccharides as anomeric mixtures, whereas anomeric de‐ O ‐acetylation in methanol resulted in a moderate‐to‐excellent yield. Reactions with various unprotected monosaccharides or disaccharides followed by a semi‐one‐pot sequential conversion into the corresponding acetylated glycosyl hemiacetal also resulted in high yields. Furthermore, the obtained hemiacetals could be successfully transformed into trichloroimidates after Dy(OTf) 3 ‐catalyzed glycosylation.