Synthesis of XylβCer, Galβ1−4XylβCer, NeuAcα2−3Galβ1−4XylβCer and the Corresponding Lactone and Lactam Trisaccharides

Wilstermann, Michael; Magnusson, Göran

doi:10.1021/jo970298k

Cited by 28 publications

(11 citation statements)

References 29 publications

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“…In an alternative approach, we have synthesized ganglioside lactams, which are quite stable against hydrolysis and have conformations very similar to those of the ganglioside lactones . A cyclic ether analogue of G M3 -1‘‘→2‘-lactone has also been reported .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Lactam and Acetamido Analogues of Sialyl Lewis x Tetrasaccharide and Lewis x Trisaccharide

1998

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Virtually complete regioselective galactosylation of the diol acceptor p-methoxyphenyl 6-O-benzyl-2-deoxy-2-tetrachlorophthalimido-β-d-glucopyranoside (15) with the donors ethyl 3,4-di-O-acetyl-6-O-benzyl-2-deoxy-2-[[(2,2,2-trichloroethoxy)carbonyl]amino]-1-thio-β-d-galactopyranoside (14), 4methylphenyl 2,3-di-O-acetyl-4-azido-6-O-benzyl-4-deoxy-1-thio-β-d-galactopyranoside (30), and 4-methylphenyl 2-O-acetyl-4-azido-6-O-benzyl-4-deoxy-3-O-(methoxyethanoyl)-1-thio-β-d-galactopyranoside (44) gave the lactose-diamine derivatives 16, 33, and 45, respectively. Fucosylation of the NHAc derivatives of 16 and 33 (17 and 34) with the donor 18 gave, after deprotection and N-acetylation, the 2-NHAc-Lex and 4-NHAc-Lex trisaccharides 3 and 5, respectively. Removal of the Troc group from the tetrasaccharide intermediate 23, followed by N-acetylation (→ 24), gave the NHAc-SLex tetrasaccharide 2. Regioselective sialylation of the partially protected trisaccharide diols 21 and 37 with the sialyl donors 22 and 38 gave, after deprotection and lactamization, the SLex-1‘‘‘→2‘-lactam 1 and the SLex-1‘‘‘→4‘-lactam 4, respectively. The stannylidene acetal of the trisaccharide diol 21 was regioselectively 3-O-alkylated with tert-butyl bromoacetate; reductive removal of the Troc protecting group and addition of methanolic MeONa caused formation of a lactam ring. Compound 40 was thus obtained over four steps in an overall yield of 52%. Deprotection of 40 furnished the Lex-3,2-lactam 6 in 74% yield. Fucosylation of the lactose−diamine derivative 46 with donor 18 gave the N3-Lex trisaccharide derivative 47. The azido function of 47 was reduced with H2S, which caused spontaneous closure of a lactam ring. Removal of the protecting groups then gave the Lex-3,4-lactam 7. The total yields of 1, 2, 3, 4, 5, and 7 from the monosaccharide starting materials 14, 15, 18, 22, 30, 38, and 44 were 10%, 10%, 22%, 14%, 62%, and 28%, respectively.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Lactam and Acetamido Analogues of Sialyl Lewis x Tetrasaccharide and Lewis x Trisaccharide

1998

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“…The synthesis of ganglioside lactams corresponding to G M2 , G M3 and G M4 ganglioside lactones has been reported previously. [40][41][42] They proved to be very stable upon storage with only minor hydrolysis occuring in D 2 O at 37 • C during one month. It was also found that antibodies raised towards G M3 -lactam cross-reacted with the G M3lactone in vitro.…”

Section: Hydrolysis Of Lactone Products 10a and 10bmentioning

confidence: 97%

Formation of lactones from sialylated MUC1 glycopeptides

Pudelko¹,

Lindgren²,

Tengel³

et al. 2006

Org. Biomol. Chem.

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The tumor-associated carbohydrate antigens TN, T, sialyl TN and sialyl T are expressed on mucins in several epithelial cancers. This has stimulated studies directed towards development of glycopeptide-based anticancer vaccines. Formation of intramolecular lactones involving sialic acid residues and suitably positioned hydroxyl groups in neighboring saccharide moieties is known to occur for glycolipids such as gangliosides. It has been suggested that these lactones are more immunogenic and tumor-specific than their native counterparts and that they might find use as cancer vaccines. We have now investigated if lactonization also occurs for the sialyl TN and T antigens of mucins. It was found that the model compound sialyl T benzyl glycoside , and the glycopeptide Ala-Pro-Asp-Thr-Arg-Pro-Ala from the tandem repeat of the mucin MUC1, in which Thr stands for the 2,3-sialyl-T antigen, lactonized during treatment with glacial acetic acid. Compound gave the 1''--> 2' lactone as the major product and the corresponding 1''--> 4' lactone as the minor product. For glycopeptide the 1''--> 4' lactone constitued the major product, whereas the 1''--> 2' lactone was the minor one. When lactonized was dissolved in water the 1''--> 4' lactone underwent slow hydrolysis, whereas the 1''--> 2' remained stable even after a 30 days incubation. In contrast the corresponding 2,6-sialyl-TN glycopeptide did not lactonize in glacial acetic acid.

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“…Although that 1,2-orthoesters can usually be rearranged into the 1,2- trans -glycoside by Brønsted- or Lewis acids, − this was not achievable with the lanthanide triflates investigated by Adinolfi et al It was also shown that acid washed 4 Å mol sieves improved the yield of the Yb(OTf) 3 -catalyzed glycosylation . The use of acid-washed molecular sieves in glycosylations had previously been reported sporadically in the literature, − and it is arguably not surprising that adding more acid to the reaction mixture resulted in a more efficient activation of the acid-labile TCA donors. The Iadonisi group later reported that 4 Å acid washed mol sieves were able to activate TCA donors in the absence of a Lewis acid .…”

Section: Glycosyl Imidate Donorsmentioning

confidence: 99%

Catalytic Glycosylations in Oligosaccharide Synthesis

2018

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Catalytic glycosylation has been a central reaction in carbohydrate chemistry since its introduction by Fischer 125 years ago, but it is only in the past three to four decades that catalytic methods for synthesizing oligosaccharides have appeared. Despite the development of numerous elegant and ingenious catalytic glycosylation methods, only a few are in general use. This review covers all methods of catalytic glycosylation with the focus on the development and application in oligosaccharide synthesis and provide an overview of the scope and limitations of these. The review also includes relevant mechanistic studies of catalytic glycosylations. The future of catalytic glycosylation chemistry is discussed, including specific, upcoming methods and possible directions for the field of research in general.

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Synthesis of XylβCer, Galβ1−4XylβCer, NeuAcα2−3Galβ1−4XylβCer and the Corresponding Lactone and Lactam Trisaccharides

Cited by 28 publications

References 29 publications

Synthesis of Lactam and Acetamido Analogues of Sialyl Lewis x Tetrasaccharide and Lewis x Trisaccharide

Synthesis of Lactam and Acetamido Analogues of Sialyl Lewis x Tetrasaccharide and Lewis x Trisaccharide

Formation of lactones from sialylated MUC1 glycopeptides

Catalytic Glycosylations in Oligosaccharide Synthesis

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