168139-76-2Relevant academic research and scientific papers
Glycosyl imidates, 74: Synthesis of ganglioside GM1 via a GM3 intermediate
Greilich, Ulrike,Brescello, Roberto,Jung, Karl-Heinz,Schmidt, Richard R.
, p. 663 - 672 (2007/10/03)
The synthesis of GM1 (1) via GM3 intermediate 7 was based on lactose building-block 5, sialyl donors 6, and a Galβ(1-3)-GalN3 donor 13α. Reaction of donor 13α with acceptor 7 in the presence of TMSOTf as catalyst afforded GM1 pentasaccharide 30. Azido group reduction, N-acetylation, hydrogenolytic O-debenzylation, and O-acetylation furnished O-acyl-protected GM1 pentasaccharide 34. Chemoselective 1a-O-deacetylation and generation of O-(pentaosyl)trichloroacetimidate 36 provided the required glycosyl donor for the application to azidosphingosine glycosylation procedure affording GM1 (1). VCH Verlagsgesellschaft mbH, 1996.
Solid-phase synthesis of a glycosylated hexapeptide of human sialophorin, using the trichloroacetimidate method
Rademann, Joerg,Schmidt, Richard R.
, p. 217 - 226 (2007/10/02)
A hexapeptide containing a β-D-Gal p-(13)-α-D-Gal pNAc-(1O)-L-threonine unit was synthesized using glycosylated pentafluorophenyl esters in an Fmoc-based strategy.In all of the glycosylation reactions, trichloroacetimidates were successfully employed.The disaccharide moiety was prepared from tetra-O-acetyl-α-D-galactopyranosyl trichloroacetimidate and tert-butyldimethylsilyl 2-azido-6-O-benzoyl-2-deoxy-β-E-galactopyranoside with boron trifluoride etherate as a catalyst.The glycosylated active esters were obtained in the reaction of α and β 2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl-(13)-4-O-acetyl-2-azido-6-O-benzoyl-2-deoxy-D-galactopyranosyl trichloroacetimidates with Fmoc-protected pentafluorophenyl esters of L-serine and L-threonine in the presence of trimethylsilyl trifluoromethanesulfonate as Lewis acid.The glycosylated pentafluorophenyl ester of L-threonine was transformed into glycopeptides via a solid-phase synthesis.Azide reduction and N-acetylation were performed on the solid phase with a thioacetic acid-pyridine mixture.The glycopeptide was then cleaved from the resin with strong acid, also removing the acid-labile protecting groups of the peptide chain.Finally, the acyl groups used for sugar protection were cleaved with sodium methoxide, affording the completely deprotected N-acetyl-L-leucyl-L-glutamyl-O-3)-2-acetamido-2-deoxy-α-D-galactopyranosyl>-L-threonyl-L-seryl-L-threonyl-glycinamide (1) in high purity. Keywords: O-Glycopeptides; Glycosyl trichloroacetimidates; Peptide synthesis, solid phase; N-Fmoc protection; Pentafluorophenyl esters
Glycosyl Imidates, 73. Synthesis of Ganglioside GM1 via a GA1 Intermediate
Stauch, Thomas,Greilich, Ulrike,Schmidt, Richard R.
, p. 2101 - 2112 (2007/10/03)
The synthesis of GM1 pentasaccharide 36 via GA1-intermediate 24 was based on lactose building block 11, Galβ(1-3)GalN3 building block 23, and sialyl donors 32.For the synthesis of 11, tetra-O-acetyl galactosyl trichloroacetimidate 3 or 2,3-di-O-acetyl-4,6-O-benzylidene-galactosyl trichloroacetimidate 5 as donors were allowed to react with 4-O-unprotected glucose derivative 4 as acceptor to afford lactose derivatives 6 and 7, respectively, in high yields.They were readily transformed via 8 into 2b,3b-O-MPM-protected 9; reductive opening of the dioxane ring with DIBAH furnished regioselectively the desired 4b-O-unprotected lactose derivative 11.From donor 3 and 6-O-benzoyl-protected 2-azidoglucose 19 as acceptor Galβ(1-3)GalN3 disaccharide 20 was synthesized which was readily converted into per-O-acyl-protected trichloroacetimidate 23.Reaction of 23 with 11 afforded upon Sn(OTf)2 catalysis the desired β-linked tetrasaccharide 24 in high yield.Removal of the MPM-protective groups with DDQ furnished 2b,3b-O-unprotected derivative 31, which gave by treatment with sialyl donors 32a and 32b GM1-pentasaccharide intermediate 33 in good yield. 2b-O-Acylation and then hydrogenolysis in the presence of Pearlman's catalyst and ensuing peracetylation afforded O-acyl-protected GM1-pentasaccharide 36 which was alredy previously converted into GM1. - Keywords: Glycosylsphingolipids; Ganglio series; Glycoside synthesis; O-Glycosyl trichloroacetimidates; Sialyl phosphite
