A new method for the synthesis of glycosyl fluorides

Rosenbrook, William; Riley, David; Lartey, Paul A.

doi:10.1016/s0040-4039(00)98450-8

Cited by 158 publications

(30 citation statements)

References 7 publications

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“…Peroxidase-conjugated rabbit anti-rat IgM (-chain specific; Zymed Laboratories Inc., South San Francisco, CA) was used for GL7, and peroxidase-conjugated goat anti-mouse IgM (-chain specific; Cappel Laboratories, Malvern, PA) was used for other antibodies. The pure synthetic ␣2-6-sialylated 6-sulfo-LacNAc determinant was synthesized by established methods from three building blocks, a sialic acid donor (27), a lactosamine donor (28), and lactosyl cholestanol with a free hydroxyl residue at CЈ-3 (29). Lactosyl cholestanol was coupled with the lactosamine donor using a catalytic amount of bis(cyclopentadienyl)hafnium(IV) dichloride-silver triflate (Cp 2 HfCl 2 -AgOTf) according to the method of Matsumoto et al (30).…”

Section: Methodsmentioning

confidence: 99%

Human B-lymphocytes Express α2-6-Sialylated 6-Sulfo-N-acetyllactosamine Serving as a Preferred Ligand for CD22/Siglec-2

Kimura

Ohmori

Miyazaki

et al. 2007

Journal of Biological Chemistry

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CD22/Siglec-2, an important inhibitory co-receptor on B-lymphocytes, is known to recognize ␣2-6-sialylated glycan as a specific ligand. Here we propose that the ␣2-6-sialylated and 6-GlcNAc-sulfated determinant serves as a preferred ligand for CD22 because the binding of a human B-cell line to CD22 was almost completely abrogated after incubating the cells with NaClO 3 , an inhibitor of cellular sulfate metabolism, and was also significantly inhibited by a newly generated monoclonal antibody specific to the ␣2-6-sialylated 6-sulfo-Nacetyllactosamine (LacNAc) determinant (KN343, murine IgM). The ␣2-6-sialylated 6-sulfo-LacNAc determinant defined by the antibody was significantly expressed on a majority of normal human peripheral B-lymphocytes as well as follicular B-lymphocytes in peripheral lymph nodes. The determinant was also expressed in endothelial cells of high endothelial venules of secondary lymphoid tissues, including lymph nodes, tonsils, and intestine-associated lymphoid tissues, more strongly than on B-lymphocytes, suggesting a role for CD22 in B-cell interaction with blood vessels and trafficking. These results indicate that the ␣2-6-sialylated 6-sulfoLacNAc determinant serves as an endogenous ligand for human CD22 and suggest the possibility that 6-GlcNAc sulfation as well as ␣2-6-sialylation may regulate CD22/Siglec-2 functions in humans.CD22/Siglec-2 (sialic acid-binding immunoglobulin-like lectins) is an important inhibitory receptor on B-lymphocytes. It controls the signaling threshold of B-cell receptors, preventing their overactivation (1-4). It has inhibitory immunoreceptor tyrosine-based inhibitory motifs in its cytoplasmic domain and regulates B-cell receptor signaling by recruiting the tyrosine phosphatase SHP-1 (Src homology 2 domain-containing protein-tyrosine phosphatase-1) (5). It is known to also affect distribution and trafficking of B-lymphocytes, such as in the homing of IgD ϩ B-lymphocytes to the bone marrow (6). Disruption of CD22 is known to result in production of high affinity autoantibodies, an increase in follicular mature B-lymphocytes, and a reduction in the number of marginal zone B-lymphocytes (7, 8).CD22/Siglec-2 is known to specifically bind to its ligand, ␣2-6-sialylated glycan (9 -12). B-lymphocytes themselves significantly express ␣2-6-sialylated glycan on their surface, which can serve as a cis-ligand for endogenous CD22, thus masking the ligand binding activity of CD22 on the majority of B-lymphocytes. CD22/Siglec-2 is proposed to exert trans-interaction with target cells expressing ␣2-6-sialylated glycans only when expression of the endogenous cis-ligand is suppressed or when the trans-ligand on target cells has a significantly higher binding activity than the cis-ligand (13,14). For better understanding of CD22 function, it is important to know the diversity of ␣2-6-sialylated glycans and to find candidate glycans that preferentially bind to CD22.In mice, it has long been known that CD22 prefers the ␣2-6-N-glycolylsialic acid terminus over the ␣2-6-N-acetylsiali...

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Section: Methodsmentioning

confidence: 99%

Human B-lymphocytes Express α2-6-Sialylated 6-Sulfo-N-acetyllactosamine Serving as a Preferred Ligand for CD22/Siglec-2

Kimura

Ohmori

Miyazaki

et al. 2007

Journal of Biological Chemistry

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“…Efficient glycosyl donors such as trichloroacetimidates ( 5 ) and fluorides (6) can also be prepared after hydrolysis of the anomeric 0-nitrate. Several methods were reported for the latter transformation (5,7,8).…”

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confidence: 99%

Preparation of diversely protected 2-azido-2-deoxyglycopyranoses from glycals

Czernecki¹,

Ayadi²

1995

Can. J. Chem.

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A new and efficient preparation of diversely protected 2-azido-2-deoxyglycopyranosides from the corresponding glycals is described. The glycals are first transformed into protected phenyl 2-azido-2-deoxyselenoglycopyranosides by azido-phenylselenylation. Two procedures were employed according to the protecting groups present: sodium azide and diphenyldiselenide in the presence of (diacetoxyiodo)benzene for peracetylated glycals (Procedure A) or trimethylsilyl azide and tetra-n-butylammonium fluoride in the presence of N-phenylselenophthalimide for perbenzylated glycals (Procedure B). A gluco-manno mixture (90%) is obtained from protected d-glucal whereas only the galacto isomer is formed from protected d-galactal(75%). The compatibility of the second procedure with one free hydroxyl group and a variety of protecting groups was verified with 1,5-anhydro-2-deoxy-3,4-O-isopropylidene-d-lyxo-hex-l -enitol and its 6-0-acety I, 6-0-allyl, 6-0-benzyl, and 6-0-tert-butyldimethylsilyl derivatives as well as with 1,s-anhydro-4,6-0-benzylidene-2-deoxy-d-lyxohex-1-enitol and its 3-0-acetyl and 3-0-benzyl derivatives, which were transformed into phenyl2-azido-2-deoxy-a-d-selenogalactopyranoside derivatives in good yield. In the second step, hydrolysis of these selenoglycosi&s afforded diversely protected glycopyranoses in high yield. Peracetylated derivatives were hydrolyzed in the presence of N-iodosuccinimide, whereas mercury trifluoroacetate was employed for 3,4-0-isopropylidene, 4,6-0-benzylidene, and perbenzylated derivatives. In some cases the two steps can be canied out without isolation of the intermediate selenoglycoside.Key words: glycals, 2-azido-2-deoxygalactopyranose, 2-azido-2-deoxyglucopyranose, selenoglycosides.RCsumC : On dCcrit une nouvelle prCparation efficace de divers 2-azido-2-dCsoxyglycopyranosides protCgCs de diverses manikres 8 partir des glycals correspondants. Dans la premikre Ctape, on transforme les glycals en 2-azido-2-dCsoxysCICnoglycopyranosides de phenyle protCgCs par azidophCnylsClCnylation. On a utilisC deux mCthodes suivant la nature des groupes protecteurs presents : azoture de sodium et diphCnyldisClCnure en prCsence de (diac6toxyiodo)benzkne avec les glycals peracCtylCs (rnCthode A) ou azoture de trimCthylsilyle et fluorure de tCtra-n-butylammonium en prCsence de N-phCnylsC1Cnophtalimide avec les glycals perbenzylCs (mCthode B). On obtient un mClange gluco-manno (90%) 8 partir du d-glucal alors que l'on obtient uniquement l'isornkre galacto 8 partir du d-galactal(75%). Utilisant le 1,5-anhydro-2-dCsoxy-3,4-O-isopropylidkne-d-lyxohex-1-Cnitol et ses dCrivCs ainsi que le 1,sanhydro-4,6-O-benzylidkne-2-dCsoxy-d-lyo-hex-l-Cnitol et ses derives 3-0-acCtyl-et 3-0-benzyl-qui ont CtC transformis en dCrivCs du 2-azido-2-dCsoxy-a-galactopyranoside de phCnyle avec de bons rendements, on a vCrifiC la compatibilitk de la deuxikme mCthode avec la prtsence d'un groupe hydroxyle libre et de divers groupes protecteurs. Dans la deuxikme Ctape, l'hydrolyse de ces sClCnoglycosides fournit divers ...

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“…The 4-hydroxyl group in the GalN3 residue was protected as a chloroacetate, before the anomeric silyl group was split in the presence of TBAF and AcOH. Resulting hemiacetal 19 was then converted to a mixture of a-and b‰uorides 20 (a W b＝3 W 4) by treating with DAST 17,18) in THF. The Cp2Zr(ClO4)2-promoted glycosylation 19) of Fmoc serine allyl ester 5 with tetrasaccharyl donor 20 in CH 2 Cl 2 was poorly stereoselective to aŠord 21 and 22 in 40z and 33z yields, respectively, although highly a-selective glycosylation of the serine and threonine derivatives had been achieved with the related disaccharyl glycosyl ‰uoride in the previous studies.…”

Section: Resultsmentioning

confidence: 99%