Shigehiro Hirano

Oxidation of carbohydrates with methyl sulfoxide containing phosphorus pentaoxide : I. Synthesis of some aldosuloses and aldosiduloses

Abstract Methyl sulfoxide containing phosphorus pentaoxide oxidizes secondary alcohol groups of carbohydrates to ketones. Oxidation proceeds most efficiently with N,N-dimethylformamide as solvent and with 3–4 molar equivalents of methyl sulfoxide and 1.5–2.0 molar equivalents of phosphorus pentaoxide. The following carbohydrates were oxidized to afford the corresponding aldosuloses and aldosiduloses in good or moderate yields: methyl4,6- O -benzylidene-2- O -( p -tolylsulfonyl)-α- D -gluco- and allo-pyranoside ( 1 and 18 ), methyl 2-acetamido-4,6- O -benzylidene-2-deoxy-α- D -gluco- and -allo-pyranoside ( 3 and 19 ), 1,2:5,6-di- O -isopropylidene-α- D -glucofuranose (6),1,2- O- isopropylidene-5- O -( p -tolylsulfonyl)-α- D -xylo- and -ribo-furanose ( 11 and 13 ), 1,2- O -isopropylidene-5- O -(di- O -phenylphosphono)-α- D -xylofuranose ( 14 ), and 1,2- O -isopropylidene-α- D -glucofuranurono-6,3-lactone ( 16 ).

Conformational studies on some g̈a-glycopyranose derivatives

Abstract The conformations of eleven α-glycopyranosides and glycosylamine derivatives, and their acyl derivatives, were studied by n.m.r. spectral analysis in deuterium oxide and in methyl sulfoxide- d 6 . In deuterium oxide at room temperature, the α-glycosylamines examined were found to exist as a rapidly equilibrating mixture of the two chair conformations, but, in methyl sulfoxide- d 6 at room temperature, they were found to exist mainly in the 1C ( D ) [ C1 ( L )] conformation. However, the α-glycosides and their acyl derivatives examined were found to exist mainly in the C1 ( D ) [ 1C ( L )] conformation in various solvents.

Infrared spectra of the sulfonic esters of monosaccharides

Abstract The orientation of sulfonyloxy groups at different carbon atoms of the pyranose ring of monosaccharides has been examined by analysis of infrared spectra in the 800–900 cm −1 region, with particular reference to axial and equatorial orientations of the sulfonyloxy groups. Axial sulfonyloxy groups show a strong absorption band at 880–890 cm −1 , whereas equatorial ones absorb at 840–850 cm −1 . The absorption frequency is not affected by variations in the kind of hexopyranose, by the kind and position of the sulfonyloxy groups on the pyranose ring, or by the kind of phase used for the measurement.

Polysaccharide synthesis from mono- and oligo-saccharides by the action of phosphorus pentoxide in dimethyl sulphoxide

Abstract Phosphorus pentoxide-dimethyl sulphoxide (P 4 O 10 -DMSO) was found predominantly to catalyse the polymerization reaction of carbohydrates at below 35°C and the oxidation reaction at 60–65°C. A series of new synthetic polysaccharides were prepared from mono- and oligo-saccharides including 2-acetamido-2-deoxy- d -glucose and hexuronic acids in up to 48% yield by the action of P 4 O 10 -DMSO at 10–25°C. These synthetic polysaccharides showed s 20,w 0.68–1.34S, and the degree of polymerization fell in 15.3–4.7 monosaccharide units per polysaccharide chain on the basis of reducing end-group assay. A structural analysis by the methylation of the synthetic glucan (2) revealed α-1,4- and α-1,6-glucosidic linkages as main chains with various branchings. The synthetic polysaccharides contained 1.3–15.9% phosphorus, but the linkages are unknown.

Nucleosides and related substances : Part IV. The synthesis of 9-α-d-glucopyranosyladenine by the fusion reaction

Abstract An anomeric mixture of nucleosides is produced in the fusion of 2,3,4,6-tetra- O -acetyl- d -glucopyranose, and various i - O -substituted derivatives thereof, with 6-benzamidopurine in the presence of certain catalysts. 9-α- d -Glucopyranosyladenine was isolated from the anomeric mixture obtained by the fusion of 2,3,4,6-tetra- O -acetyl- i - O -trichloroacetyl-α- d -glucopyranose with 6-benzamidopurine in the presence of toluene- p -sulphonic acid as catalyst.

Sialic acid and related substances : Part II. A comparative assay of N-acetylneuraminic acid

Abstract The assays of N -acetylneuraminic acid by the thiobarbituric acid, resorcinol, and direct Ehrlich methods were investigated comparatively by a statistical examination, in order to study the factors influencing color formation. Interference with color formation in the assay with the thiobarbituric acid method was similar to that with the direct Ehrlich method, and different from that with the resorcinol method.

Isolation of 2-amino-2-deoxy-d-galactoside disaccharide from chondroitin sulfate C

Purified chondroitin sulfate prepared from shark cartilage (chondroitin sulfate C) was desulfated and esterified with methanolic HCl. Chondroitin methyl ester (II) was reduced with NaBH4 to give carboxyl-reduced chondroitin (III), which was submitted to hydrazinolysis to remove the acetyl group of the 2-acetamido-2-deoxy-d-galactopyranose moiety. The N-deacetylated carboxyl-reduced chondroitin (IV) was dyrolyzed with HCl and the hydrolyzate was passed down a Dowex-50 (H+) column. A disaccharide (V) and 2-amino-2-deoxy-d-galactopyranose adsorbed on the column were eluted with dilute HCl. Both the substances were N-acetylated and separated effectively by means of a cellulose powder column (Solvent B), and a novel disaccharide, 4-O-(β-2-acetamido-2-deoxy-d-galactopyranosyl)-d-glucopyranose (VII), was isolated. The reducing end of the isolated disaccharide was reduced with NaBH4 to give 4-O-(β-2-acetamido-2-deoxy-d-galactopyranosyl)-d-glucitol (VIII). Acid hydrolysis of this substance gave d-glucitol (IX) and 2-amino-2-deoxy-d-galactopyranose (X), which were characterized by infrared spectra and by paper chromatography. The structures of these substances (VII, VIII) were confirmed by means of periodate oxidation.

Methylation of Heparin, Heparitinsulfate, and Hexa, Tetra and Trisaccharides from Hyaluronic Acid

The methylations of heparin, heparitinsulfate, and three oligosaccharides (hexa, tetra and trisaccharides) from hyaluronic acid were carried out. Theoretical amounts of methoxyl group were obtained from the oligosaccharides and the desulfated product of carboxyl-reduced heparitinsulfate, but not from heparin and heparitinsulfate. The acid hydrolysis of the methylated trisaccharide confirms that the structure is β-d-glucopyranosyl uronic acid-(1→3) -2-acetamido-2-deoxy-β-d-glucopyranosyl- (1→4) -d-glucopyranosyl uronic acid.

Nucleosides and Related Substances:Part III. Syntheses of O -Glycosides, Glycosylamines and Purine Nucleosides by Fusion Reaction in the Presence of Polyphosphoric Acid or Ethyl Polyphosphate as New C_??_talyst

Polyphosphoric acid and ethyl polyphosphate were newly applied as catalyst to the syntheses of O-glycosides, glycosylamines and purine nucleosides in good yields by fusion reaction of fully acetylated sugars with some aglycons. The isolated ones were the acetylated phenyl O-glycosides of β-d-glucofuranurono-6,3-lactone in 82% yield, of methyl α,β-d-galactopyranuronate in 83% yield, of β-d-glucopyranose in 76% yield, of α-cellobiose in 25% yield and of α-l-rhamnopyranose in 55% yield, p-cresyl 2,3,4,6-tetra-O-acctyl-β-d-glucopyranoside in 70% yield, the acetyl derivatives of N-p-tolyl β-, N-phenyl α-, N-2-naphthyl α- and N-m-nitrophenyl α-d-glucopyranosylamines in the yields of 70, 55, 81 and 12%, respectively, N-7-(2′, 3′, 4′, 6′-tetra-O-acetyl-β-d-glucopyranosyl) theophylline in 83% yield, N-7-β-d-glycosyl theophylline of d-glucopyranose, of d-xylopyranose and of d-ribopyranose in the yields of 63, 43 and 35%, respectively, and N-9-(2′, 3′, 4′, 6′-tetra-O-acetyl-β-d-glucopyranosyl)-6-benzamidopurine in 2...

Sialic Acids and Related Substances:Part I. Reaction of N-Acetyl-D-galactosamine and Oxalacetic Acid

N-Acetyl-D-galactosamine, N-acetyl-D-mannosamine and N-acetyl-D-glucosamine were allowed to react with oxalacetic acid under alkaline conditions, and the condensation products purified by ion-exchange chromatography. Properties of these products on the whole are similar to each other, though there is a minor but significant diference in the condensation product with N-acetyl-D-galactosaminc. Paper chromatograms of the condensation products suggest that N-acetyl-D-galactosamine as well as N-acetyl-D-glucosamine are epimerized partly before they condense with oxalacetic acid to givc each two sialic acids with different configurations at C-5 from each other.