The 2-Naphthylmethyl (NAP) Group in Carbohydrate Synthesis: First Total Synthesis of the GlyCAM-1 Oligosaccharide Structures
摘要:
Total syntheses of the GlyCAM-1 (glycosylation-dependent cell adhesion molecule-1) oligosaccharide structures: [alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 4)-[alpha-Fuc-(1 --> 3)]-beta-(6-O-SO3Na)-GlcNAc-(1 --> 6)]-[alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 3)]-alpha-GalNAc-OMe (1) and [alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 4)-[alpha-Fuc-(1 --> 3)]-beta-GlcNAc-(1 --> 6)]-[alpha-NeuAc-(2 3)-beta-Gal-(1 --> 3)]-alpha-GalNAc-OMe (2) through a novel sialyl LewisX tetrasaccharide donor are described. Employing sequential glycosylation strategy, the starting trisaccharide was regio- and stereoselectively constructed through coupling of a disaccharide imidate with the monosaccharide acceptor phenyl-6-O-naphthylmethyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside with TMSOTf as a catalyst without affecting the SPh group. The novel sialyl Lewisx tetrasaccharide donor 3 was then obtained by alpha-L-fucosylation of trisaccharide acceptor with the 2,3,4-tri-O-benzyl-1-thio-beta-L-fucoside donor. The structure of the novel sialyl Lewisx tetrasaccharide was established by a combination of 2D DQF-COSY and 2D ROESY experiments. Target oligosaccharides 1 and 2 were eventually constructed through heptasaccharide which was obtained by regioselective assembly of advanced sialyl Lewisx tetrasaccharide donor 3 and a sialylated trisaccharide acceptor in a predictable and controlled manner. Finally, target heptasaccharides 1 and 2 were fully characterized by 2D DQF-COSY, 2D ROESY, HSQC, HMBC experiments and FAB mass spectroscopy.
The 2-Naphthylmethyl (NAP) Group in Carbohydrate Synthesis: First Total Synthesis of the GlyCAM-1 Oligosaccharide Structures
摘要:
Total syntheses of the GlyCAM-1 (glycosylation-dependent cell adhesion molecule-1) oligosaccharide structures: [alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 4)-[alpha-Fuc-(1 --> 3)]-beta-(6-O-SO3Na)-GlcNAc-(1 --> 6)]-[alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 3)]-alpha-GalNAc-OMe (1) and [alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 4)-[alpha-Fuc-(1 --> 3)]-beta-GlcNAc-(1 --> 6)]-[alpha-NeuAc-(2 3)-beta-Gal-(1 --> 3)]-alpha-GalNAc-OMe (2) through a novel sialyl LewisX tetrasaccharide donor are described. Employing sequential glycosylation strategy, the starting trisaccharide was regio- and stereoselectively constructed through coupling of a disaccharide imidate with the monosaccharide acceptor phenyl-6-O-naphthylmethyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside with TMSOTf as a catalyst without affecting the SPh group. The novel sialyl Lewisx tetrasaccharide donor 3 was then obtained by alpha-L-fucosylation of trisaccharide acceptor with the 2,3,4-tri-O-benzyl-1-thio-beta-L-fucoside donor. The structure of the novel sialyl Lewisx tetrasaccharide was established by a combination of 2D DQF-COSY and 2D ROESY experiments. Target oligosaccharides 1 and 2 were eventually constructed through heptasaccharide which was obtained by regioselective assembly of advanced sialyl Lewisx tetrasaccharide donor 3 and a sialylated trisaccharide acceptor in a predictable and controlled manner. Finally, target heptasaccharides 1 and 2 were fully characterized by 2D DQF-COSY, 2D ROESY, HSQC, HMBC experiments and FAB mass spectroscopy.
Acyl Group Migration and Cleavage in Selectively Protected β-<scp>d</scp>-Galactopyranosides as Studied by NMR Spectroscopy and Kinetic Calculations
作者:Mattias U. Roslund、Olli Aitio、Johan Wärnå、Hannu Maaheimo、Dmitry Yu. Murzin、Reko Leino
DOI:10.1021/ja801177s
日期:2008.7.1
protective groups and their relative stabilities at variable pH for a series of beta- d-galactopyranoses were studied by NMR spectroscopy. The clockwise and counterclockwise migration rates for the different ester groups were accurately determined by use of a kinetic model. The results presented provide new insights into the acid and base stabilities of commonly used ester protectinggroups and the phenomenon
Studies Directed toward the Synthesis of Polysialogangliosides: The Regio- and Stereocontrolled Synthesis of Rationally Designed Fragments of the Tetrasialoganglioside GQ<sub>1b</sub><sup>+</sup>.
The synthesis of suitably protected fragments of the tetrasialoganglioside GQ1b (I), i.e., 1 (alpha-NeuAc2 -->-8-alpha-NeuAc2 --> 3-beta-Gal1 --> 4Glc), 2 (alpha-NeuAc2 --> 8-alpha-NeuAc2 --> 3Gal), 3 (GalNAc), 4 (alpha-NeuAc2 --> 8NeuAc), 5 (beta-Gal1 -->- 3GalNAc), and 42 [beta-Gal1 --> 3-beta-GalNAc1 --> 4(alpha-NeuAc2 --> 3)beta-Gal --> 4Glc], is described. All are rationally designed so that the protecting groups can be regioselectively introduced and removed, as needed, before or after the stereoselective coupling of an appropriate pair of fragments. The syntheses of 1, 2, and 4 all feature stereoselective glycosylations by glycosyl donors that bear a C-3 thiophenoxy stereocontrolling auxiliary. Compound 3 was prepared from the D-glucosamine derivative 17 by way of a novel intramolecular nucleophilic displacement with inversion of configuration. Furthermore, model glycosylations of 4-hydroxygalactose derivatives, in which the thioglycoside 3 and the fluoride 40 served as glycosyl donors, were performed. The reaction of 3 with the glycosyl acceptor 30 gave the disaccharide 31 (GalNAc-beta-1 --> 4Gal), whereas that of 40 with 41 afforded the pentasaccharide 42.
The 2-Naphthylmethyl (NAP) Group in Carbohydrate Synthesis: First Total Synthesis of the GlyCAM-1 Oligosaccharide Structures
作者:Jie Xia、James L. Alderfer、Conrad. F. Piskorz、Khushi L. Matta
Total syntheses of the GlyCAM-1 (glycosylation-dependent cell adhesion molecule-1) oligosaccharide structures: [alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 4)-[alpha-Fuc-(1 --> 3)]-beta-(6-O-SO3Na)-GlcNAc-(1 --> 6)]-[alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 3)]-alpha-GalNAc-OMe (1) and [alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 4)-[alpha-Fuc-(1 --> 3)]-beta-GlcNAc-(1 --> 6)]-[alpha-NeuAc-(2 3)-beta-Gal-(1 --> 3)]-alpha-GalNAc-OMe (2) through a novel sialyl LewisX tetrasaccharide donor are described. Employing sequential glycosylation strategy, the starting trisaccharide was regio- and stereoselectively constructed through coupling of a disaccharide imidate with the monosaccharide acceptor phenyl-6-O-naphthylmethyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside with TMSOTf as a catalyst without affecting the SPh group. The novel sialyl Lewisx tetrasaccharide donor 3 was then obtained by alpha-L-fucosylation of trisaccharide acceptor with the 2,3,4-tri-O-benzyl-1-thio-beta-L-fucoside donor. The structure of the novel sialyl Lewisx tetrasaccharide was established by a combination of 2D DQF-COSY and 2D ROESY experiments. Target oligosaccharides 1 and 2 were eventually constructed through heptasaccharide which was obtained by regioselective assembly of advanced sialyl Lewisx tetrasaccharide donor 3 and a sialylated trisaccharide acceptor in a predictable and controlled manner. Finally, target heptasaccharides 1 and 2 were fully characterized by 2D DQF-COSY, 2D ROESY, HSQC, HMBC experiments and FAB mass spectroscopy.