The Total Synthesis of the Neurogenic Ganglioside LLG‐3 Isolated from the Starfish <i>Linckia laevigata</i>

Tamai, Hideki; Ando, Hiromune; Tanaka, Hidenori; Hosoda-Yabe, Ritsuko; Yabe, Tomio; Ishida, Hideyuki; Kiso, Makoto

doi:10.1002/anie.201006035

Cited by 63 publications

(46 citation statements)

References 32 publications

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“…Partial O→N migration of acetyl groups 67–68 was observed in the course of the hydrogenolysis resulting in complex reaction mixtures. Consequently, the crude reaction mixtures were acetylated, thereby completing the process of acetamide formation and enabling the isolation of the peracetates in high yield (Table 3).…”

Section: Resultsmentioning

confidence: 99%

Stereoselective Synthesis of 5-epi-α-Sialosides Related to the Pseudaminic Acid Glycosides. Reassessment of the Stereoselectivity of the 5-Azido-5-deacetamidosialyl Thioglycosides and Use of Triflate as Nucleophile in the Zbiral Deamination of Sialic Acids

2016

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With a view to the eventual synthesis of glycosyl donors for the stereocontrolled synthesis of pseudaminic acid glycosides, the stereocontrolled synthesis of a d-glycero-d-gulo sialic acid adamantanylthioglycoside carrying an axial azide at the 5-position is described. The synthesis employs levulinic acid as nucleophile in the oxidative deamination of an N-acetyl neuraminic acid thioglycoside leading to the formation of a 3-deoxy-d-glycero-d-galacto-2-nonulosonic acid (KDN) derivative selectively protected as 5-O-levulinate. Replacement of the levulinate by triflate enables introduction of the axial azide and hence formation of the glycosyl donor. A shorter synthesis uses trifluoromethanesulfonate as nucleophile in the oxidative deamination step when the 5-O-triflyl KDN derivative is obtained directly. Glycosylation reactions conducted with the 5-azido-d-glycero-d-gulo configured sialyl adamantanylthioglycoside at −78 °C are selective for the formation of the equatorial glycosides suggesting that the synthesis of equatorial pseudaminic acid glycosides will be possible as suitable donors become available. A comparable N-acetylneuraminic acid adamantanylthioglycoside carrying an equatorial azide at the 5-position was also found to be selective for equatorial glycoside formation under the same conditions, suggesting that reinvestigation of other azide-protected NeuAc donors is merited. Glycosylation stereoselectivity in the d-glycero-d-gulo series is discussed in terms of the side chain conformation of the donor.

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Section: Resultsmentioning

confidence: 99%

Stereoselective Synthesis of 5-epi-α-Sialosides Related to the Pseudaminic Acid Glycosides. Reassessment of the Stereoselectivity of the 5-Azido-5-deacetamidosialyl Thioglycosides and Use of Triflate as Nucleophile in the Zbiral Deamination of Sialic Acids

2016

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“…With phytoceramide 24 in hand, we synthesized the glucosyl ceramide cassette for the final conjugation with the oligosaccharyl donor (Scheme ). Glucosyl imidate donor 26 was prepared from known phenylthioglycoside 25 9. Treatment of 25 with NBS in acetone/H 2 O19 at room temperature, and subsequent imidoylation of the resulting 1‐OH with CCl 3 CN and DBU20 in CH 2 Cl 2 at 0 °C gave 26 in 90 % yield over two steps.…”

Section: Resultsmentioning

confidence: 99%

Vanadium(V) Oxo and Imido Calix[8]arene Complexes: Synthesis, Structural Studies, and Ethylene Homo/Copolymerisation Capability

Redshaw

Walton

Lee

et al. 2015

Chemistry A European J

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Interaction of p‐tert‐butylcalix[8]areneH8 (L8H8) with [NaVO(OtBu)4] (formed in situ from VOCl3) afforded the complex [Na(NCMe)5][(VO)2L8H]⋅4 MeCN (1⋅4 MeCN). Increasing [NaVO(OtBu)4] to 4 equiv led to [Na(NCMe)6]2[(Na(VO)4L8)(Na(NCMe))3]2⋅10 MeCN (2⋅10 MeCN). With adventitious oxygen, reaction of 4 equiv of [VO(OtBu)3] with L8H8 afforded the alkali‐metal‐free complex [(VO)4L8(μ3‐O)2] (3); solvates 3⋅3 MeCN and 3⋅3 CH2Cl2 were isolated. For the lithium analogue, the order of addition had to be reversed such that lithium tert‐butoxide was added to L8H8 and then treated with 2 equiv of VOCl3; crystallisation afforded [(VO2)2Li6[L8](thf)2(OtBu)2(Et2O)2]⋅Et2O (4⋅Et2O). Upon extraction into acetonitrile, [Li(NCMe)4][(VO)2L8H]⋅8 MeCN (5⋅8 MeCN) was formed. Use of the imido precursors [V(NtBu)(OtBu)3] and [V(Np‐tolyl)(OtBu)3] and L8H8, afforded [tBuNH3][{V(p‐tolylN)}2L8H]⋅3 1/2 MeCN (6⋅3 1/2 MeCN). The molecular structures of 1 to 6 are reported. Complexes 1, 3, and 4 were screened as precatalysts for the polymerisation of ethylene in the presence of cocatalysts at various temperatures and for the copolymerisation of ethylene with propylene. Activities as high as 136 000 g (mmol(V) h)−1 were sometimes achieved; higher molecular weight polymers could be obtained versus the benchmark [VO(OEt)Cl2]. For copolymerisation, incorporation of propylene was 7.1–10.9 mol % (compare 10 mol % for [VO(OEt)Cl2]), although catalytic activities were lower than [VO(OEt)Cl2].

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“…Each C3 position of the galactose residues should be protected by the different selectively removable protecting groups because they are potential sites to introduce the sulphate group. To date, we have succeeded in the efficient total synthesis of natural gangliosides such as GQ1b, 13 GalNAc-GD1a, 14 GalNAc-GM1b, 15 X2, 16 LLG-3 17 and GAA-7, 18 using the GlcCer cassette approach. 19 This approach has been proven to be able to overcome a long-standing issue in glycolipid synthesis, namely that coupling of the flexible, poor reactive ceramide acceptor and the oligosaccharyl donor results in low yield and loss of the valuable oligosaccharide unit.…”

Section: Resultsmentioning

confidence: 99%

“…MeCN was selected as a solvent to obtain the pure amino derivative before the following acetyl migration step because our previous study on the synthesis of a ganglioside found that MeCN effectively suppressed random acetyl group migration. 17 To rapidly convert 15 into the acceptor form 16 , acetyl migration from 3- O to 2- N was exerted. Although this reaction was attempted several times under different conditions, the undesired formation of 17 , which was the over-migrated product from 4- O to 3- O , could not be avoided.…”

Section: Resultsmentioning

confidence: 99%

Total syntheses of disulphated glycosphingolipid SB1a and the related monosulphated SM1a

et al. 2015

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Total syntheses of two natural sulphoglycolipids, disulphated glycosphingolipid SB1a and the structurally related monosulphated SM1a, are described. They have common glycan sequences and ceramide moiety and are associated with human epithelial carcinomas. The syntheses featured efficient glycan assembly and the glucosyl ceramide cassette as a versatile building block. The binding of the synthetic sulphoglycolipids by the carcinoma-specific monoclonal antibody AE3 was investigated using carbohydrate microarray technology.

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The Total Synthesis of the Neurogenic Ganglioside LLG‐3 Isolated from the Starfish Linckia laevigata

Cited by 63 publications

References 32 publications

Stereoselective Synthesis of 5-epi-α-Sialosides Related to the Pseudaminic Acid Glycosides. Reassessment of the Stereoselectivity of the 5-Azido-5-deacetamidosialyl Thioglycosides and Use of Triflate as Nucleophile in the Zbiral Deamination of Sialic Acids

Stereoselective Synthesis of 5-epi-α-Sialosides Related to the Pseudaminic Acid Glycosides. Reassessment of the Stereoselectivity of the 5-Azido-5-deacetamidosialyl Thioglycosides and Use of Triflate as Nucleophile in the Zbiral Deamination of Sialic Acids

Vanadium(V) Oxo and Imido Calix[8]arene Complexes: Synthesis, Structural Studies, and Ethylene Homo/Copolymerisation Capability

Total syntheses of disulphated glycosphingolipid SB1a and the related monosulphated SM1a

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