160243-03-8Relevant academic research and scientific papers
Fucosylation of linear alcohols: A study of parameters influencing the stereochemistry of glycosylation
Vermeer, Henricus J.,Van Dijk, Christiaan M.,Kamerling, Johannis P.,Vliegenthart, Johannes F. G.
, p. 193 - 203 (2007/10/03)
L-Fucose is a constituent of many glycoconjugates and often has a key role in the epitope involved in biological functions. The chemical synthesis of such compounds is necessary to generate sufficient material to explore the molecular details of their bioactivity. In this context, the development of practical and stereoselective α-fucosylation reactions is essential. Here are described several procedures for fucosylation of linear alcohols 9-16 with L-fucose (1) and a series of 2-O-benzyl-protected fucopyranosyl donors 3-8, together with parameters influencing the stereochemistry of glycosylation, such as protecting groups, catalysts, and dielectric constants of solvents. Although high α-selectivities have often been reported for fucosylation reactions with glycosyl acceptors, complete α-selectivity was never observed here, using linear spacer alcohols 9-16. Generally, the best α-selectivities were obtained in fucosylations of the alcohols under in situ anomerization conditions using tetrabutylammonium bromide (75-90% α-anomer), whereas promotion by NIS/TfOH(cat.) proceeded with poor stereoselectivity in treatment of the ethyl thiofucosides 3-5. No directing effects from the 4-O protecting groups were noted. For the 2-O-benzyl-protected 1-O-thioethyl fucopyranosyl donors 3-5, electronic effects of the fucosyl donor could not explain the observed stereoselectivity. The difference between the observed selectivities for α-fucosylations of glycosyl acceptors, in comparison with the linear spacer alcohols used here, is probably due to steric effects of the more bulky glycosyl acceptors.
Synthesis of the 5-aminopentyl glycoside of β-D-Galp-(1->4)-β-D-GlcpNAc-(1->3)-L-Fucp and fragments thereof related to glycopeptides of human Christmas factor and the marine sponge Microciona prolifera
Ziegler, Thomas
, p. 195 - 212 (2007/10/02)
The marine sponge Microciona prolifera and human coagulation factor IX (Christmas factor)-related mono- to tri-saccharide 5-aminopentyl glycosides β-D-Galp-R (5), β-D-GlcpNAc-R (16), β-D-Galp-(1->4)-β-D-GlcpNAc-R (26), β-D-GlcpNAc-(1->3)-β-L-Fucp-R (39), β-D-GlcpNAc-(1->3)-α-L-Fucp-R (43), β-D-Galp-(1->4)-β-D-GlcpNAc-(1->3)-β-L-Fucp-R (45), and β-D-Galp-(1->4)-β-D-GlcpNAc-(1->3)-α-L-Fucp-R (47), where R is a 5-aminopentyloxy spacer moiety, which allowed the construction of glycoconjugates, were prepared.Thus 3,4,6-tri-O-acetyl-2-deoxy-2-(2,2,2-trichloroethoxycarbonylamino)-α-D-glucopyranosyl trichloroacetimidate (10) and 1,3,4,6-tetra-O-acetyl-2-chloroacetamido-2-deoxy-β-D-glucopyranose (13) were condensed with N-Z-protected 5-aminopentanol (2) followed by conversion of the coupling products into the corresponding N-acetylglucosamine derivatives, to give compound 16 after deblocking.Similarly, the donors 10 and 13 were coupled to position 3 of suitably protected aminopentyl β- (32) and α- (37) -L-fucopyranosides, to give the disaccharides 39 and 43, respectively.Starting from lactose, O-(2,3,4,6-tetra-O-benzoyl-β-D-galactopyranosyl)-(1->4)-3,6-di-O-benzoyl-2-deoxy-2-(2,2,2-trichloroethoxycarbonylamino)-α-D-glucopyranosyl trichloroacetimidate (23) was prepared and used as an efficient disaccharide donor for the construction of ligand 26 from 2 and of the trisaccharide ligands 45 and 47 from fucosides 32 and 37, respectively.Key words: Christmas factor, human; Coagulation factor IX; Human marine sponge Microciona prolifera; Aminopentyl glycoside
