499-16-1Relevant articles and documents
One-step conversion of cellobiose to C6-alcohols using a ruthenium nanocluster catalyst
Yan, Ning,Zhao, Chen,Luo, Chen,Dyson, Paul J.,Liu, Haichao,Kou, Yuan
, p. 8714 - 8715 (2007/10/03)
The one-step conversion of cellulose to C6-alcohols via green and energy efficient approaches has, as far as we are aware, not been reported. Such a process presents a considerable challenge, the two key problems being (1) finding a suitable solvent that dissolves the cellulose, and (2) the development of advanced catalytic chemistry for selective cleavage of the C-O-C bonds (glycosidic bonds) connecting glucose residues. The dissolution of cellulose has been recently realized by using ionic liquids as green solvents; there is still no efficient method, such as selective hydrogenation, for the precise C-O-C cleavage under mild conditions, however. Cellobiose is a glucose dimer connected by a glycosidic bond and represents the simplest model molecule for cellulose. We disclose in this communication that the one-step conversion of cellobiose to C6-alcohols can be realized by selectively breaking the C-O-C bonds via selective hydrogenation using a water-soluble ruthenium nanocluster catalyst under 40 bar H2 pressure. Copyright
Sequential removal of monosaccharides from the reducing end of oligosaccharides and uses thereof
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, (2008/06/13)
Methods are provided for the sequential removal of monosaccharides from the reducing end of oligosaccharides. The present invention also discloses the use of such methods for structural determinations of oligosaccharides and to enable new structures to be generated from pre-existing oligosaccharides. In addition, the methods of the present invention may be automated by the incorporation into systems.
SYNTHESIS OF A CLOSE ANALOG OF THE REPEATING UNIT OF THE ANTIFREEZE GLYCOPROTEINS OF POLAR FISH
Anisuzzaman, Abul Kashem M.,Anderson, Laurens,Navia, Juan L.
, p. 265 - 278 (2007/10/02)
The protected glycopeptide N-(benzyloxycarbonyl)-L-alanyl-3)-O-(2,4,6-tri-O-benzyl-α-D-galactopyranosyl)-(1->3)>-L-threonyl-L-alanine 2,2,2-trichloroethyl ester (21) was made by coupling the respective disaccharide and tripeptide blocks.The disaccharide block was generated by coupling tetra-O-benzoyl-α-D-galactopyranosyl bromide to allyl 2,4,6-tri-O-benzyl-α-D-galactopyranoside and converting the product into O-(2,3,4,6-tetra-O-benzoyl-β-D-galactopyranosyl)-(1->3)-2,4,6-tri-O-benzyl-α-D-galactopyranosyl chloride (6) via the 1-propenyl glycoside and the free (1-OH) sugar.Alternatively, the 1-propenyl intermediate was obtained directly by using 1-propenyl 2,4,6-tri-O-benzyl-α-D-galactopyranoside (10) as the acceptor in the initial coupling reaction.An efficient 3-step synthesis of 10 was accomplished by the dibutyltin oxide-assisted, selective crotylation of allyl α-D-galactopyranoside at O-3, followed by benzylation and treatment of the product with potassium tert-butoxide.The N-benzyloxycarbonyl (Z) and N-tert-butoxycarbonyl (Boc) 2,2,2-trichloroethyl esters of Thr-Ala and Ala-Thr-Ala were formed by sequential coupling.The silver triflate-promoted glycosylation of the Z-protected dipeptide and tripeptide by 2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl chloride, and of the tripeptide by 6, proceeded with excellent α-stereoselectivity.From the disaccharide tripeptide 21, the carboxyl-deprotected and fully deproptected derivatives were prepared.