Stereoselektive Synthese von Î²-D-Mannopyranosiden mit reaktiven Mannopyranosyldonoren mit einer benachbarten elektronenziehenden Gruppe Diese Arbeit wurde unterstÃ¼tzt von der Deutschen Forschungsgemeinschaft, dem Fonds der Chemischen Industrie und der EuropÃ¤ischen Gemeinschaft (Bewilligung Nr. HPRN-CT-2000-00001/GLYCOTRAIN). A. A.-H. A.-R. und E. S. H. E. A. danken der Alexander-von-Humboldt-Stiftung fÃ¼r ein Forschungsstipendium bzw. fÃ¼r die fortwÃ¤hrende UnterstÃ¼tzung.

Abdel‐Rahman, Adel A.‐H.; Jonke, Simon; Ashry, El Sayed H. El; Schmidt, Richard R.

doi:10.1002/1521-3757(20020816)114:16<3100::aid-ange3100>3.0.co;2-0

Cited by 26 publications

(10 citation statements)

References 5 publications

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“…Introduction of one equivalent of p ‐TolSCl to a mixture of armed donor 1 , AgOTf, and MS‐AW300 in diethyl ether at −60 °C led to instantaneous complete activation of the glycosyl donor 11. Addition of the acceptor 4 to the pre‐activated donor rapidly formed disaccharide 9 in just a few minutes, which was isolated in 87 % yield as the α anomer due to the anomeric effect (Table 1, entry 1).…”

Section: Methodsmentioning

confidence: 99%

Iterative One‐Pot Synthesis of Oligosaccharides

et al. 2004

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Section: Methodsmentioning

confidence: 99%

Iterative One‐Pot Synthesis of Oligosaccharides

et al. 2004

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“…Hence, for the selective attachment of different antennae at the 2‐ O position of Man residues d and d′, orthogonal protection of Man residue c is required, as exhibited by building block 4 . Because of the lack of a highly β‐selective mannosyl donor,18, 19 the required Manβ(1‐4)GlcN disaccharide donor 4 had to be prepared independently (Scheme ).…”

Section: Methodsmentioning

confidence: 99%

Efficient Solid-Phase Synthesis of a Complex, Branched N-Glycan Hexasaccharide: Use of a Novel Linker and Temporary-Protecting-Group Pattern

Grathwohl

Schmidt

2002

Angew. Chem. Int. Ed.

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Oligosaccharides are known to be important molecules in various biological processes; therefore, they have gained increasing interest in recent years. [1] However, in contrast to oligopeptides [2] and oligonucleotides [3] which are routinely constructed on automated synthesizers employing standardized building blocks and polymer supports, no generally applied synthetic methodology has yet appeared for the solidphase synthesis of complex oligosaccharides. [4] Success in this challenging task would provide several advantages over solution-phase techniques: 1) the required standardized building blocks could become commercially available, 2) an excess of building blocks and/or reagents could be used to drive reactions to completion, 3) the synthesis could become much faster, and 4) purification procedures could become simpler.Another fundamental key issue for solid-phase oligosaccharide synthesis is the availability of a high-yielding and stereoselective glycosylation strategy. Of the various glycosyl donors employed for this purpose, [5±11] O-glycosyl trichloroacetimidates [12] are suitable because of their high glycosyldonor properties in the presence of just catalytic amounts of a (Lewis) acid. In combination with solvent and temperature effects, type of catalyst, protecting-group pattern, and anchimeric assistance these donors also permit the desired control of the stereoselectivity at the anomeric center. [13] An additional requirement for solid-phase oligosaccharide synthesis is access to branching which is found in many oligosaccharides and glycoconjugates but not in peptides and oligonucleotides. Thus, for chain extension and branching, besides permanently protected functional groups, to be liberated only after completion of the solid-phase oligosaccharide synthesis, a suitable temporary-protectinggroup pattern is required. This temporary-protecting-group pattern provides the orthogonality required for branching and should also accommodate the demands of the linker which necessitates an additional temporary functional group.Based on our recent studies on new temporary protecting groups, [12, 14] new linker types, [14] and the synthesis of branched oligosaccharides, [12e, 15] we report herein a novel strategy which COMMUNICATIONS 4489 were measured at low temperatures (4.2 K or 78 K). The source was kept at room temperature. Spectra were recorded over a velocity range of AE 25 mm s À1 using an NaI(Tl) scintillation counter. Fitting of the spectra was carried out on the basis of the theoretically expected lineshape arising from the allowed transitions between the quadrupolar-split energy levels of the ground state (I ¼ 5/2) and the excited state (I ¼ 7/2).[10] a) The compound crystallizes in the monoclinic space group P2 1 /c, a ¼ 11.743 (2). Lorentz, polarization, and absorption corrections; 17 068 reflections; range 1.74 q 27.53; 9436 unique data; 8164 with I ! 2s(I). Structure solution was performed with SHELXS-97 using direct methods. [10b] Refinement was done against F 2 using SHELXL-97. [10c] All ...

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“…The m-nitro and p-nitro group in the benzene ring of the benzylsulfonyl group 76 was also found to direct the glycosylation towards the β. Thus, the βanomers 86 and 87 were isolated in 57 and 45% yield, respectively [66]. Deprotection of the 2-O-benzylsulfonyl group was readily performed by the action of sodium amide in DMF at room temperature [31,33] (Scheme 20).…”

Section: Electron-withdrawing Substituents On 2-omentioning

confidence: 99%