The mechanism of the Stevens rearrangement

Ollis, W. D.; Rey, Max; Sutherland, I. O.; Closs, G. L.

doi:10.1039/c39750000543

Cited by 39 publications

(18 citation statements)

References 2 publications

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“…A slight rate enhancement is observed for the formation of 3-and 4-thiocyclohexyl radicals (Table 5-6). It is argued that the observed rate enhancement together with the diminished Δ£* supports the existence of transannular participation by sulfur (Ohno and Ohnishi, 1972).…”

Section: The Nature Of Radical Stabilization By Sulfurmentioning

confidence: 78%

“…(1968); Uneyamarte/. (1969) fragmentation Uneyama et al (1971); Ohno et al (1971) Barton and McGombic, 1975) substituted radicals, are illustrative (the types of reactions involved are indicated by the appropriate letter; isolated products are underscored).…”

Section: (5-7)mentioning

confidence: 99%

“…The stereospecificity of thiol addition Me M e^V^H D However, the data on C 2 H 5 SCH 2 C(CH 3 ) 2 -N=N-C(CH 3 ) 2 CH 2 SG 2 H 5 decomposition in Table 5-3 indicate that, to the extent that the transition state for this reaction resembles the radical intermediate, no particular stabilization can be attributed to the j8-ethylthiyl group (Ohno and Ohnishi, 1971c). Furthermore, Kampmeier has shown that the hydrogens of di-tertbutyl sulfide, which are ß to sulfur, show no special reactivity in abstraction Ohno and Ohnishi (1972). by the phenyl radical (Hepinstall and Kampmeier, 1973).…”

Section: The Nature Of Radical Stabilization By Sulfurmentioning

confidence: 99%

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Sulfur-Containing Radical

1978

Organic Chemistry: A Series of Monographs

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Section: The Nature Of Radical Stabilization By Sulfurmentioning

confidence: 78%

Section: (5-7)mentioning

confidence: 99%

Section: The Nature Of Radical Stabilization By Sulfurmentioning

confidence: 99%

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Sulfur-Containing Radical

1978

Organic Chemistry: A Series of Monographs

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“…a-D-Altropyranose has been reported to exist in aqueous solution as an equilibrium mixture of 4C1 and 'C4 conformers while /?-Daltropyranose exists as a 4C1 conformer [24]. It should also be noted that the crystalline conformations of both methyl a-D-altropyranoside [25, 261 and penta-0-acetyl-a-D-altropyranose [27] have been shown to adopt the 4C1 pyranoid form. For compound A in the 4C1 form (see Fig.…”

Section: Gal ( ] -4 )~G a L ( I -3 )~G A L N A C O Lmentioning

confidence: 99%

“…It should also be noted that the crystalline conformations of both methyl a-D-altropyranoside [25, 261 and penta-0-acetyl-a-D-altropyranose [27] have been shown to adopt the 4C1 pyranoid form. …”

Section: Gal ( ] -4 )~G a L ( I -3 )~G A L N A C O Lmentioning

confidence: 99%

Identification and determination of absolute and anomeric configurations of the 6-deoxyaltrose residue found in polysialoglycoprotein of Salvelinus leucomaenis pluvius eggs. The first demonstration of the presence of a 6-deoxyhexose other than fucose in glycoprotein

Iwasaki

Inoue

1987

Eur J Biochem

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An oligosaccharide alditol, dHex-GalNAc-Gal-Gal-GalNAcol, has been isolated from polysialoglycoprotein, which was derived from the unfertilized eggs of Savelinus leucomuenispluvius (a salmonid fish, Iwana in Japanese), by alkaline borohydride treatment followed by exhaustive digestion with sialidase. First, the structure of the terminal dHex residue in the above pentasaccharide has been assigned as 6-deoxyaltrose (= dAlt in pyranoid form) by a combination of structural methods (GLC, TLC, mass spectrometry, and 400-MHz 'H-NMR spectroscopy). The occurrence of a 6-deoxyhexose other than L-fucose in glycoprotein has not been previously reported.Next, the absolute configuration of this unusual sugar residue has been assigned as D on the basis of the exciton-splitting study of tris-p-bromobenzoate derivatives of methyl 6-deoxyaltrosides. The usefullness of this circular dichroic exciton-splitting method in the determination of the absolute configuration of carbohydrate ' components, only available in minute amounts, is emphasized. The anomeric configuration of the glycosidic linkage of the D-altropyranosyl residue was deduced from 400-MHz 'H NMR spectroscopy. The 6-deoxy-P-~-altropyranosyl residue thus established has the same configuration as a-L-fucose but with the C-5 methyl group inverted, suggesting that the biosynthetic incorporation of D-dAlt parallels that of L-fucose, and a possible pathway is also considered. Polysialoglycoprotein (PSGP) was first isolated in 1978 byInoue and Iwasaki [l] from the unfertilized eggs of rainbow trout. Since that time similar PSGPs have been reported from the Salmonidae fish family [2, 31. The oligo(po1y)sialylglycan chains arising from the alkaline borohydrate treatment of PSGP have been described [2, 4-101. We have reported the isolation and purification of an additional asialo-core oligosaccharide (designated X pentasaccharide; X?1-3GalNAcfl1-3Gal~1-4Gal~1-3GalNAcol) from PSGP of Sulvelinus leucomaenis pluvius (see [2]).We now wish to present chemical and physicochemical evidence for the assignment of 6-deoxy-~-altrose to X, which is linked (P1 + 3) to the penultimate GalNAc residue. Until now the only known example of a deoxyhexose in the glycoconjugates of animal origin has been L-fucose while 6-deoxy-L-altrose has been known for well over a decade as a constituent of certain lipopolysaccharides [13 -161. This 6-deoxy-P-D-altropyranosyl structure in 4c1(D) conformation is also proposed as best explaining its biosynthesis. MATERIALS AND METHODSIsolation and purification of PSGP from the unfertilized eggs of Sulvelinus leucomaenis and a novel oligosaccharide, 'X pentasaccharide' have been described previously [2]. Methods for thin-layer chromatography, carbohydrate analysis, methylation analysis and GLC mass spectrometry followed closely those described previously [2, 4-61. We are indebted to Dr. H. Hashimoto, Tokyo Institute of Technology, for providing the following synthetic intermediates: methyl 2,3-di-0-benzoyl-4,6-O-benzylidene-cr-~-glucopyranoside (l), 3-0-benzoyl-l,2-...

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Reaction Mechanisms in Heterocyclic Chemistry

Heard

Yates

1998

Encyclopedia of Computational Chemistry

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The mechanism of the Stevens rearrangement

Cited by 39 publications

References 2 publications

Sulfur-Containing Radical

Sulfur-Containing Radical

Identification and determination of absolute and anomeric configurations of the 6-deoxyaltrose residue found in polysialoglycoprotein of Salvelinus leucomaenis pluvius eggs. The first demonstration of the presence of a 6-deoxyhexose other than fucose in glycoprotein

Reaction Mechanisms in Heterocyclic Chemistry

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