Showing papers on "Glycal published in 1996"
TL;DR: This review provides a personal account of the explorations of a research group in oligosaccharide and glycoconjugate construction that led to novel compounds which are in the final stages of preclinical assessment.
Abstract: This review provides a personal account of the explorations of a research group in oligosaccharide and glycoconjugate construction. The journey began twenty years ago with the study of Diels–Alder reactions of complex dienes. By extending this methodology to aldehydo-type heterodienophile equivalents, access to unnatural glycals was gained (LACDAC reaction). From this point a broad-ranging investigation of the use of glycals in the synthesis of oligosaccharides and other glycoconjugates was begun. Mobilization of glycals both as glycosyl donors and glycosyl acceptors led to the strategy of glycal assembly. Several new glycosylation techniques were developed to provide practical underpinning for this logic of glycal assembly. Glycal-based paradigms have been shown to be nicely adaptable to solid phase supported synthesis. Moreover, glycal assembly—both in solution and on solid phases—has been used to gain relatively concise and efficient entry to a variety of biologically interesting and potentially valuable constructs. Some of these syntheses, particularly in the field of tumor antigens, have led to novel compounds which are in the final stages of preclinical assessment. This review presents an account of the chemical reasoning at the center of the program.
594 citations
TL;DR: The first was constructed by intermolecular coupling of an indole anion with a 1,2-anhydrosugar derived from an endo-glycal by direct epoxidation as discussed by the authors.
Abstract: The total syntheses of staurosporine and ent-staurosporine have been achieved. Both glycosidic bonds were built from glycal precursors. The first was constructed by intermolecular coupling of an indole anion with a 1,2-anhydrosugar derived from an endo-glycal by direct epoxidation. The second bond was assembled from an exo-glycal by intramolecular iodoglycosylation.
114 citations
TL;DR: In this article, a one-pot, three-step procedure was developed for the synthesis of peracetylated glycal derivatives from various reducing sugars including D-glucose, D-galactose, L-rhamnose and L-arabinose.
78 citations
TL;DR: Addition of 2,4-dimethylbenzenesulfenyl chloride to sialic acid glycal gives crystalline 2-chloro-3-thiosialic acids 3 in 85% yield as mentioned in this paper.
Abstract: Addition of 2,4-dimethylbenzenesulfenyl chloride to sialic acid glycal gives crystalline 2-chloro-3-thiosialic acid 3 in 85% yield. Reaction of 3 with sodium thiomethoxide in acetonitrile at 0 °C a...
49 citations
TL;DR: In this article, the C-glycosidations of glycal acetates with allyltrimethylsilane 5, vinyloxytrimmethylsilane 6 or isopropenyl acetate 7 using montmorillonite K-10 as an environmentally acceptable and inexpensive industrial catalyst under mild conditions proceed effectively.
33 citations
23 citations
TL;DR: A review of the explorations of a research group in oligosaccharide and glycoconjugate construction can be found in this article, where the authors present an account of the chemical reasoning at the center of the program.
Abstract: This review provides a personal account of the explorations of a research group in oligosaccharide and glycoconjugate construction. The journey began twenty years ago with the study of Diels–Alder reactions of complex dienes. By extending this methodology to aldehydo-type heterodienophile equivalents, access to unnatural glycals was gained (LACDAC reaction). From this point a broad-ranging investigation of the use of glycals in the synthesis of oligosaccharides and other glycoconjugates was begun. Mobilization of glycals both as glycosyl donors and glycosyl acceptors led to the strategy of glycal assembly. Several new glycosylation techniques were developed to provide practical underpinning for this logic of glycal assembly. Glycal-based paradigms have been shown to be nicely adaptable to solid phase supported synthesis. Moreover, glycal assembly—both in solution and on solid phases—has been used to gain relatively concise and efficient entry to a variety of biologically interesting and potentially valuable constructs. Some of these syntheses, particularly in the field of tumor antigens, have led to novel compounds which are in the final stages of preclinical assessment. This review presents an account of the chemical reasoning at the center of the program.
22 citations
TL;DR: In this paper, O-acetylated glycal esters of Kdo mono-, α-2→8)- and α-(2→4)- linked Kdo disaccharide derivatives 1a - c with NIS in acetic acid afforded good yields of trans-diaxial as well as minor amounts of transdiequatorial and cis-configured 2-Oacetyl-3deoxy-3-iodo derivatives.
17 citations
Journal Article•
TL;DR: The "core" pentasaccharide region of high mannose asparagine-linked glycoproteins was synthesized using thioethyl donors and methyl triflate to promote coupling.
Abstract: The "core" pentasaccharide region of high mannose asparagine-linked glycoproteins was synthesized using thioethyl donors and methyl triflate to promote coupling. All monosaccharide units were prepared from glycals. The central mannose residue was installed by inversion of the C2 hydroxyl of a glucosyl precursor. The protecting group scheme employed allows for the extension of the pentasaccharide through the terminal mannose units and a peptide can be coupled through transformation of the glycal.
13 citations
TL;DR: A concise, regio- and stereoselective synthesis of the ganglioside GM3 has been achieved using an α-1,2-oxirane derived from lactal facilitated installation of the anomeric β-ceramide side chain.
Abstract: A concise, regio- and stereoselective synthesis of the ganglioside GM3 has been achieved Use of an α-1,2-oxirane derived from lactal facilitated installation of the anomeric β-ceramide side chain Introduction of the sialic acid residue at C3, of the lactose was accomplished regiospecifically by enzymatically mediated sialyl transfer from CMP-Neu-5-Ac
13 citations
TL;DR: In this paper, the peracetate methyl esters of N-acetylneuraminic acid (Neu5Ac), 3-deoxy-d-glycero-d -galacto-2-nonulosonic acid (Kdn), and 3deoxy d -manno-2 -octulosic acid with trimethylsilyl trifluoromethanesulfonate (CF3SO3SiMe3) were investigated and it was found that the choice of solvent, reaction temperature, and reaction time dramatically
Journal Article•
TL;DR: In this paper, a concise, regio-and stereoselective synthesis of the ganglioside GM3 has been achieved using an α-1,2-oxirane derived from lactal facilitated installation of the anomeric β-ceramide side chain.
Abstract: A concise, regio- and stereoselective synthesis of the ganglioside GM3 has been achieved. Use of an α-1,2-oxirane derived from lactal facilitated installation of the anomeric β-ceramide side chain. Introduction of the sialic acid residue at C3, of the lactose was accomplished regiospecifically by enzymatically mediated sialyl transfer from CMP-Neu-5-Ac.
TL;DR: Protected pentapeptide 9 has been converted to hexapeptides 3 and this chemoselectively coupled to activated ester 2 to give 1 after glycal hydration during SiO2 flash chromatography.
TL;DR: In this paper, O-acetylated glycal esters of Kdo mono-, α-2→8)- and α-(2→4)- linked Kdo disaccharide derivatives 1a - c with NIS in acetic acid afforded good yields of trans-diaxial as well as minor amounts of transdiequatorial and cis-configured 2-Oacetyl-3deoxy-3-iodo derivatives.
Abstract: Addition reactions of O-acetylated glycal esters of Kdo mono-, α-(2→8)- and α-(2→4)- linked Kdo disaccharide derivatives 1a - c with NIS in acetic acid afforded good yields of trans-diaxial as well as minor amounts of trans-diequatorial and cis-configured 2-O-acetyl-3-deoxy-3-iodo derivatives, which were efficiently reduced with Bu3SnH/AIBN to give the corresponding per-O-acetylated Kdo methyl ester derivatives. Similar reactions of 1a with NBS or NCS furnished the trans-diaxial 2-O-acetyl-3-bromo-3-deoxy- as well as 3-chloro-3-deoxy derivatives as the main products. Reaction of 1a with NBS in aqueous MeCN provided the 2,3-trans-bromohydrin derivative 11c, which upon treatment with DBU in MeCN gave the elimination product 11 and the α-2,3-anhydro derivative 12 as a suitable donor of glycosides with D-glycero-D-talo- or D-glycero-D-galacto configuration, respectively.