2-amino-2-desoxy-6-O-(D-glykofuranosylurono-6,3-lacton)-D-galaktopyranosen

Condensation of 2-amino-2-deoxy-D-galactopyranose with D-glucuronic acid or D-mannurono-6,3-lactone in the presence of hydrochloric acid gave the corresponding 2-amino-2-deoxy-6-O-(D-glycofuranosylurono-6,3-lactone)-D-galactopyranoses. The α-D configuration of the disaccharide derived from D-glucuronic acid was determined by its resistance towards β-D-glucuronidase.     

Synthèse et étude R.M.N. de disaccharides et trisaccharides dans la série du l-rhamnose

Various di- and tri-saccharides containing l-rhamnose were synthesized by condensation of 2,3,4-tri-O-acetyl- or 2,3,4-tri-O-benzoyl-α-l-rhamnopyranosyl bromide with an unblocked glycopyranoside. The determination of the anomeric configuration of l-rhamnose saccharides by n.m.r. is difficult because structure has a greater effect on the spectra than does configuration. The α and β configurations and the position of the substitution may be assigned from the chemical shifts of H-5 and CH₃. In all the compounds having a β configuration, a shielding of the methyl group and a deshielding of the H-5 proton have been observed as compared to the compounds having an α configuration. The H-5 proton and the methyl group of peracetylated, (1→3)-linked α-l derivatives always resonate at higher fields than the corresponding protons of (1→6)-linked α-l derivatives.     

The molecular-weight range of mucosal-heparin preparations.

A recently reported method describes the determination of the molecular-weight range of heparins by using an electrofocusing procedure to isolate individual molecular species. Commercially available heparins were fractionated on a column of polyacrylamide-agarose gel to give fractions whose molecular weights were estimated by viscometry. Fractions with mutually exclusive molecllar-weight ranges gave an appreciable number of common bands when subjected to the electrofocusing procedure; therefore, each of these bands cannot be formed from a single molecular species of heparin. Other mucopolysaccharides also gave band sequences indistinguishable from those of heparin; they differed in position and intensity with different ampholyte batches, and probably arose from individual molecular species of the ampholyte rather than the mucopolysaccharide. The molecular-weight range of the heparin was observed to be broader than that usually reported.     

Dérives C-glycosyliques : XIII. Nitrones de sucres

Various N-methylnitrones of sugars having a free carbonyl group were prepared by treatment with N-methylhydroxylamine. In each case, only one geometric isomer was obtained, to which the anti (Z) configuration is ascribed on the basis of the n.m.r. spectra, in particular of those obtained in the presence of an europium complex.     

Dérivés d'acides 3-(β-d-érythrofuranosyl)-pyrazolecarboxyliques

Treatment of 2,5-anhydro-1-bromo-1-deoxy-2,3-O-isopropylidene-1-p-nitrophenylhydrazono-d-ribose with methyl acetylenecarboxylate gave methyl 3-(2,3-O-isopropylidene-β-d-erythrofuranosyl)-1-p-nitrophenylpyrazole- (8) and 5-carboxylate (9). Amidification at C-5 of 8 was easier than at C-4 of 9. Similarly, dimethyl 3-(2,3-O-isopropylidene-β-d-erythrofuranosyl)- 1 - p-nitrophenylpyrazole-4,5-dicarboxylate gave specifically a 5-carbamoyl derivative, the structure of which was established by comparison of the ¹³C-n.m.r.spectrum with those of a series of glycosylpyrazoles. The correlation between the experimental values of the chemical shifts of the carbon atoms of the pyrazole ring and the values calculated by addition of the contributions of the various groups linked to the ring was better (R 0.98) than the correlations obtained by calculation by the CNDO/2 method of the total electron population (R 0.92) or of the π-electron population of each carbon atom (R 0.85).     

Structural studies of the klebsiella type 47 capsular polysaccharide

The structure of the capsular polysaccharide from Klebsiella Type 47 has been investigated. Methylation analysis and characterization of oligosaccharides obtained on acid hydrolysis were the principal methods used. The polysaccharide is composed of tetrasaccharide repeating-units, and a structure for these units is proposed.     

Influence des effets orbitalaires sur l'équilibre conformationnel des sucres à insaturation terminale de configuration E

The glycenoses and alkenes bearing an alkoxy group on the allylic carbon atom and having the general formula RCH(OR)′CHCHX (E configuration) preferentially adopt, in solution, a conformation in which the alkoxylgroup eclipses the double bond. This conformation is particularly favored when X is an electron-withdrawing group by resonance; it becomes less favored or totally unfavored when X is electron-donating by resonance. This phenomenon, which cannot be attributed to steric hindrance, is explained by inter-orbital interactions.     

In vitro comparative metabolism of 6,7-3H estrone and 6,7-3H estrone-3-sulfate in maternal and fetal guinea-pig liver]

The metabolism of [6,7-3H] estrone and of [6,7(3)H] estrone-3-sulfate have been comparatively studied in the maternal and fetal guinea-pig livers. The appearance of estradiol-17 beta resulting from the activity of the 17 beta-hydroxysteroid-dehydrogenase is more important in the fetal than in the maternal hepatic tissue. This suggests the direct transformation of estrone-3-sulfate into estradio-3-sulfate in the fetus. After incubation of the [3H] estrone, there is an abundant hepatic conjugation. The glycuroconjugated components are predominant, as well in the maternal as in the fetal hepatic tissue. For the latter-one the sulfoconjugation is inexistant. The sulfatasic activity shown after the incubation of [3H] estrone-3-sulfate is very low in the fetal hepatic tissue; in contrast, this activity is higher in the maternal tissue.     

Synthèse et propriétés physicochimiques de 5,6-didésoxy-6-halogéno-hept-5-éno-1,4-furanurononitriles

The four 5,6-dideoxy-6-halogeno-1,2-O-isopropylidene-3-O-methyl-α-d-xylo-hept-5-eno-1,4-furanurononitriles (bromo, chloro, fluoro, and iodo) were prepared by treatment of 1,2-O-isopropylidene-3-O-methyl-α-d-pentodialdo-1,4-furanose with the corresponding (cyanohalogenomethylene)triphenylphosphorane. The geometrical isomers were separated by liquid chromatography. Spectral data of the four nitriles and of corresponding enurononitriles were used for identification of configuration and conformation.