Abstract:α‐Acetobromzucker wurden aus den Acetylderivaten mittels asymm. Dibromdimethyläther (Ib) oder Brenzcatechylphosphortribromid (IIa) bzw. ‐chlordibromid (IIb) gewonnen. — Acylierte Zuckermercaptale gaben mit asymm. Dichlor‐dimethyläther (Ia) bzw. mit Ib unter Abspaltung einer Alkylmercaptogruppe die Halbmercaptalchloride bzw. ‐bromide. — Aus acylierten Aldonsäuren konnten mit Ib die Bromide gewonnen werden, Diisopropyliden‐galakturonsäure‐(1.5) und Isopropyliden‐benzalglucuronsäure‐(1.4) gaben mit Ia die entspre… Show more
“…Such a divergent glycosylation strategy would clearly complement the current “parallel” approach and warrants investigation. In this paper, we demonstrate the efficient glycosylation of carbohydrate acceptors by the known 1-chloro-1-(ethylthio)-2,3,4,5,6-penta- O -acetyl derivatives of d -glucose, d -galactose, and d -mannose. ,, The O,S -acetals so obtained are readily converted into d -furanosides by means of a convenient two-pot procedure. 1 …”
Treatment of the peracetylated ethyl dithioacetals of D-glucose, D-galactose, and D-mannose with acetyl chloride and boron trifluoride diethyl etherate at reflux yields the known acyclic 1-chloro-1-(ethylthio) derivatives. These compounds are shown to effectively glycosylate a variety of carbohydrate acceptors using silver trifluoromethanesulfonate as the promotor, affording stereospecifically the corresponding acyclic O,S-acetals in good to excellent yield. Furthermore, following deacetylation, treatment of these O,S-acetals with a mixture of mercuric salts in either methanol or dimethylformamide gives rise to disaccharides terminating in D-furanosyl residues.
“…Such a divergent glycosylation strategy would clearly complement the current “parallel” approach and warrants investigation. In this paper, we demonstrate the efficient glycosylation of carbohydrate acceptors by the known 1-chloro-1-(ethylthio)-2,3,4,5,6-penta- O -acetyl derivatives of d -glucose, d -galactose, and d -mannose. ,, The O,S -acetals so obtained are readily converted into d -furanosides by means of a convenient two-pot procedure. 1 …”
Treatment of the peracetylated ethyl dithioacetals of D-glucose, D-galactose, and D-mannose with acetyl chloride and boron trifluoride diethyl etherate at reflux yields the known acyclic 1-chloro-1-(ethylthio) derivatives. These compounds are shown to effectively glycosylate a variety of carbohydrate acceptors using silver trifluoromethanesulfonate as the promotor, affording stereospecifically the corresponding acyclic O,S-acetals in good to excellent yield. Furthermore, following deacetylation, treatment of these O,S-acetals with a mixture of mercuric salts in either methanol or dimethylformamide gives rise to disaccharides terminating in D-furanosyl residues.
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