A novel one-pot relay glycosylation has been established. The protocol is characterized by the construction of two glycosidic bonds with only one equivalent of triflic anhydride. This method capitalizes on the in situ generated cyclic-thiosulfonium ion as the relay activator, which directly activates the newly formed thioglycoside in one pot. A wide range of substrates are well-accommodated to furnish both linear and branched oligosaccharides. The synthetic utility and advantage of this method have been demonstrated by rapid access to naturally occurring phenylethanoid glycoside kankanoside F and resin glycoside merremoside D.
Regioselective C-3-O-acylation and O-methylation of 4,6-O-benzylidene-β-D-gluco- and galactopyranosides displaying a range of anomeric substituents
The regioselective C-3-O-acylation and O-methylation of a range of 4,6-O-benzylidene-β-D-gluco- and galactopyranosides has been studied. Regioselectivity is achieved by forming the copper chelate of the 2,3-diol using either sodium hydride and copper(II) chloride, or copper(II) acetylacetanoate, or copper(II) acetate, prior to introduction of the acylating or methylating agent.
Osborn, Helen M.I.,Brome, Victoria A.,Harwood, Laurence M.,Suthers, William G.
p. 157 - 166
(2007/10/03)
Regioselective C-3-O-acylation and O-alkylation of 4,6-O-benzylidene-β-D-glucopyranoside derivatives displaying a range of anomeric substituents
Regioselective C-3-O-acylation and O-alkylation of ethyl 4,6-O-benzylidene-1-thio-β-D-glucopyranoside, phenyl 4,6-O-benzylidene-β-D-glucopyranoside and phenyl 4,6-O-benzylidene-1-seleno-β-D-glucopyranoside is described. Regioselectivity is obtained by first treating the benzylidene diols with sodium hydride and copper (II) chloride to form a THF soluble copper chelate.
Gridley, Jonathan J.,Osborn, Helen M.I.,Suthers, William G.
p. 6991 - 6994
(2007/10/03)
PARTIAL SUBSTITUTION OF THIOGLYCOSIDES BY PHASE TRANSFER CATALYZED BENZOYLATION AND BENZYLATION
Partial substitution by phase transfer catalysis giving monobenzoylated and monobenzylated products from 2,3- and from 4,6-diols in ethyl 1-thio-D-hexopyranosides with the β-gluco, β-galacto- and α-manno-configurations are described.Two disaccharide thiog
Garegg, Per J.,Kvarnstroem, Ingemar,Niklasson, Annika,Niklasson, Gunilla,Svensson, Stefan C. T.
p. 933 - 954
(2007/10/02)
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