Rapid assembly of oligosaccharides: 1,2-diacetal-mediated reactivity tuning in the coupling of glycosyl fluorides

Baeschlin, Daniel K.; Green, Luke G.; Hahn, Michael G.; Hinzen, Berthold; Ince, Stuart J.; Ley, Steven V.

doi:10.1016/s0957-4166(99)00519-4

Cited by 65 publications

(28 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…16 In order to investigate any potential effect of BDA protection on the efficiency of the intramolecular glycosylation reaction inherent in the IAD approach, glycosyl donor 1 was also elaborated into the dibenzylated donor 7. Thus, BDA protected donor 1 was treated with aqueous trifluroacetic acid to afford the diol 8 (95% yield), which was then benzylated by treatment with sodium hydride and benzyl bromide to give the benzyl-protected donor 7 (88% yield).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Allyl protecting group mediated intramolecular aglycon delivery (IAD): synthesis of α-glucofuranosides and β-rhamnopyranosides

2004

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

“…Butyl lithium (1.6 M solution in hexanes) (0.48 ml, 0.76 mmol) was added and the mixture stirred for 10 min. BDA protected donor 1 (2 16. g, 5.09 mmol) was dissolved in freshly distilled THF (6 ml) and heated to 70 8C.…”

mentioning

confidence: 99%

Allyl protecting group mediated intramolecular aglycon delivery (IAD): synthesis of α-glucofuranosides and β-rhamnopyranosides

2004

View full text Add to dashboard Cite

“…Reduction of the lactonic function with freshly prepared sodium bis(2-methoxyethoxy)-aluminum (RedAl, 1.06 M toluene) afforded the hemiacetalic derivative 14 (93%). Activation of 14 as fluorinated glycoside with diethylaminosulfotrifluoride (DAST) in CH 2 Cl 2 allowed the isolation of 15 as a pseudoalpha anomer in 87% yield which, in turn, was treated with tetradecanol under Ley's glycosylation conditions (34) to afford 16 (42%). Deacetylation of pseudo-R-glycoside 16 gave the desired thioether 3 in 77% yield (Scheme 2).…”

Section: Discussionmentioning

confidence: 99%

Stable GM₃ Lactone Mimetic Raises Antibodies Specific for the Antigens Expressed on Melanoma Cells

et al. 2010

View full text Add to dashboard Cite

Immunotherapy of tumors and of melanoma in particular has a long history, and recently this therapeutic approach found a reliable scientific rationale. This biological therapy aims to teach the patient's immune system to recognize the antigens expressed on tumor cells and destroy them, leaving normal cells intact. The success of this therapy highly depends on the selection of target antigens that are essential for tumors growth and progression. The overexpression of GM(3) ganglioside 1 and especially the expression of its metabolite GM(3) lactone 2 characterize murine and human melanomas, playing an important role in tumor progression and making such self-antigens potential targets for the immunotherapy of these neoplasms. Although more immunogenic than its precursor, GM(3) lactone 2 is unsuitable to be used in immunotherapy as a melanoma-associated antigen (MAA) because it is unstable under physiological conditions. We designed and synthesized the hydrolytically stable mimetic 3, which is remarkably simpler than the native lactone 2; after conjugation of 3 to the protein carrier keyhole-limpet hemocyanin (KLH), the obtained glycoprotein 5 was used as the immunogen in vivo to successfully elicit specific antimelanoma antibodies. In fact, no appreciable binding to GM(1) was observed. Capitalizing on the stability and on the reduced structural complexity of mimetic 3, the immunostimulant 5 we report represents a new promising synthetic glycoconjugate for the immunotherapy of melanoma.

show abstract

“…It was determined that S-benzoxazyl glycosyl donors having both a participating moiety at C2 and an electronically armed lone pair at O5, such as the superarmed glycosyl donor shown above, were exceptionally reactive. The armed-disarmed concept, although discovered with O-pentenyl glycosides, has been found to be applicable to many other classes of glycosides such as thioglycosides [6], selenoglycosides [39], fluorides [40], phosphoroamidates [41], substituted thioformimidates [42], glycals [21], S-benzoxazolyl (SBox), and S-thiazolinyl (STaz) [43,44].…”

Section: Superarmed Glycosyl Donors In Glycosylation Reactionsmentioning

confidence: 99%

Armed-Disarmed Concept in the Synthesis of Glycosidic Bond

Miljković

2013

Electrostatic and Stereoelectronic Effects in Carbohydrate Chemistry

View full text Add to dashboard Cite

-Reid et al. reported [1] that n-pentenyl glycosides undergo chemospecific cleavage 1 ! 2 ! 3, with N-bromosuccinimide under conditions that leave a wide variety of other protecting groups unaffected ( Fig. 5.1).According to the proposed mechanism ( Fig. 5.1), the addition of water to the reaction mixture will lead to hydrolysis but the addition of alcohol or another sugar having a free hydroxyl group will lead to the formation of glycoside or a disaccharide. In the course of these studies, Fraser-Reid et al. [1] observed that sugar molecules having an acyloxy group at the C2 carbon (6 in Fig. 5.2) hydrolyzed much more slowly than if they had an alkoxy group (7 in Fig. 5.2). This observation suggested that the n-pentenyl glycoside could be made more or less reactive (it could be armed or disarmed) by the type of protecting group placed on the C2 oxygen.The ability of the C2 acyloxy group to disarm the n-pentenyl glycoside was rationalized as shown in Fig. 5.3. Thus, it can be assumed that the cyclic halonium ions 8 and 9 are formed reversibly [2] and that the electron density on the glycosidic oxygen is depleted in 2-O-acyl derivatives so that nucleophilic attack of this oxygen on the halonium ion is less favored than in the 2-O-alkyl counterpart 9. The reason for this is that the electron-withdrawing group at the C2 carbon makes the C2 carbon slightly positively charged so that the formation of another positive charge at the C1 carbon is not a favorable process [there cannot exist two positive charges on two neighboring carbons (C1 and C2) (Fig. 5.3).].Consequently, the armed glycosyl donors react with electrophiles faster than the disarmed ones, and therefore in a solution containing both an armed and disarmed glycosyl donor molecules, whereby disarmed glycosyl donor molecules have one free hydroxyl group, the reaction with an electrophile will result in crosscoupling and not self-coupling, i.e., an armed glycosyl donor will react with the disarmed one, whereas a disarmed donor will not react with itself [3] as illustrated in Fig. 5.5. The promoters for the activation of n-pentenyl group [4,5] are iodonium dicollidine perchlorate (IDCP) and N-iodosuccinimide/triethylsilyl triflate (NIS/Et 3 SiOTf).M. Miljkovic, Electrostatic and Stereoelectronic Effects in Carbohydrate Chemistry,

show abstract

Rapid assembly of oligosaccharides: 1,2-diacetal-mediated reactivity tuning in the coupling of glycosyl fluorides

Cited by 65 publications

References 74 publications

Allyl protecting group mediated intramolecular aglycon delivery (IAD): synthesis of α-glucofuranosides and β-rhamnopyranosides

Allyl protecting group mediated intramolecular aglycon delivery (IAD): synthesis of α-glucofuranosides and β-rhamnopyranosides

Stable GM₃ Lactone Mimetic Raises Antibodies Specific for the Antigens Expressed on Melanoma Cells

Armed-Disarmed Concept in the Synthesis of Glycosidic Bond

Contact Info

Product

Resources

About

Rapid assembly of oligosaccharides: 1,2-diacetal-mediated reactivity tuning in the coupling of glycosyl fluorides

Cited by 65 publications

References 74 publications

Allyl protecting group mediated intramolecular aglycon delivery (IAD): synthesis of α-glucofuranosides and β-rhamnopyranosides

Allyl protecting group mediated intramolecular aglycon delivery (IAD): synthesis of α-glucofuranosides and β-rhamnopyranosides

Stable GM3 Lactone Mimetic Raises Antibodies Specific for the Antigens Expressed on Melanoma Cells

Armed-Disarmed Concept in the Synthesis of Glycosidic Bond

Contact Info

Product

Resources

About

Stable GM₃ Lactone Mimetic Raises Antibodies Specific for the Antigens Expressed on Melanoma Cells