摘要:

3, 6-Di-O-methyl-d-glucose was preparedvia5-O-allyl-1, 2-O-isopropylidene-3-O-methyl-αd-glucofuranose and was converted into 2, 4-di-O-acetyl-3, 6-di-o-methyl-dD-glucopyranosy 1 chloride. Condensation of the chlorosugar with methanol or allyl 2, 3-O-isopropylidene-α-l-rhamnopyranoside gave the corresponding crystalline β-glycbsides. The allyl 4-O-(2,4-di-O-acetyl-3, 6-di-O-Tnethyl-β-dD-glucopyranosyl)-2, 3-O-isopropylidene-α-l-rhamnopyranoside was converted into the title compounds and into crystalline 2, 3-di-O-acetyl-4-O-(2, 4-di-O-benzyl-3, 6-di-O-methyl-β-d-glucopyranosyl)-l-rhamnopyranosyl chloride which should serve as an intermediate for the synthesis of the trisaccharide portion of the major glycolipid ofMycobacterium leprae.

ISSN:0732-8303    

DOI:10.1080/07328308308057870

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Theerythroandthreochiral C5methyl ketones (4) and (5), prepared from the (2S, 3R)-methyl diel (1b), were converted into the phenylsulfenimines (6) and (7), which, in turn, on reaction with allyl-magnesiutn bromide, yielded after acid hydrolysis and benzoylation, the diastereoisomeric C8-N-aminodiol derivatives (9) and (11), withthreostereochemistry relative to positions 4 and 5. Ozonolysis of (9) and (11) yielded thel-arabinoandl-xylo3-O-methyl branched aminodeoxysugar derivatives (13) and (15), respectively. Using diallylzinc as the reagent, the diastereoisomeric erythro products (8) and (10) were obtained. The latter materials gave thel-ribo-andl-lyxo-(lL-vancosamine) derivatives (12) and (14) upon oxonolysis. The1H and13C NMR spectra of the four isomeric aminodeoxysugar derivatives (12)—(15) were discussed.

ISSN:0732-8303    

DOI:10.1080/07328308308057871

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A study was made concerning the effect of substituants at0-3,0-4 and0-6 ofd-galactal andd-glucal (1, 5-anhydro-2-deoxy-d-lyxo- and -d-arabino-hex-1-enitol, respectively) on the double bond reactivity in the chloroazide addition reaction. Results from the quantum chemical calculations of the model structures (ab initio) and also of the whole cyclic molecules in the half-chair conformation (MINDO-3) together with the reaction indices of olefin carbon atoms are presented. These studies snow that (1) the double bond reactivity and the chloroazide addition mechanism are only affected by the substituent at0-3; (2) the influence of the acyl group is only due to its inductive effect; (3) no interaction between the acyl and the olefin fragments through space was detected. Three0-acetyl-di-0-benzyl-d-galactals were synthesized.

ISSN:0732-8303    

DOI:10.1080/07328308308057872

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Fully protected 1-thioglycopyranosyl esters ofN-acylamino acids (5,6, and7) were prepared by condensation of methyl 2, 3, 4-tri-O-acetyl-1-thio-β-d–glucopyranuronate (1), 2, 3, 4-tri-O-acetyl-1-thio-l–arabinopyranose (2), and 2, 3, 4-tri-O-acetyl-1-thio-D-arabinopyranose (3) with pentachlorophenyl esters ofN-acylamino acids in the presence of imidazole. The13C NMR chemical shifts of the starting 1-thio sugars and the 1-thiol ester products are reported.

ISSN:0732-8303    

DOI:10.1080/07328308308057873

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

O-4-O-6 Acetyl migrations in partially O-acetylated 2- and 3-acylamidodeoxyhexopyranosides, including derivatives of kanamycin A, were found to be particularly suited to allow the regiospecific accessibility of their respectiveC-4OHgroups. PartiallyO-acetylatedd-glucopyranosides, compared to the substrates above, showed slightly different aptitudes of migration. However, allO-4-O-6 migrations investigated proved to be irreversible under the conditions applied.

ISSN:0732-8303    

DOI:10.1080/07328308308057874

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The treatment of pentitols in concentrated hydrochloric acid causes 1, 4 (or 2, 5) intramolecular dehydration with either retention or change of configuration, 1, 5-dehydration and chlorine for hydroxyl substitution. These mono- and dichloroalditol derivatives mostly with the configuration of arising anhydro compounds, are formed from the alditols themselves or 1, 4-anhydro-pentitols.

ISSN:0732-8303    

DOI:10.1080/07328308308057875

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Regioselective reductive ring openings of 4, 6-O-benzylidene acetals of hexopyranosides are described using borane trimethylamine-aluminium chloride. Using toluene as solvent, 4-O-benzyl ethers with the 6-OH free are obtained. Using tetrahydrofuran as solvent. 6-O-benzyl ethers with the 4-OH free are obtained.

ISSN:0732-8303    

DOI:10.1080/07328308308057876

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Methyl 6-deoxy-6-fluoro-β-d-galactopyranoside has been obtained by treatment of methyl β-d-galactopyranoside with diethyl-aminosulfur trifluoride (DAST). Improvements over the existing syntheses of methyl 2, 3-di-O-benzyl-4-deoxy-4-fluoro-β-d-galacto-pyranoside from the corresponding 6-O-substituted 4-O-arylsul-fonyl-d-gluco derivatives are described.13C NMR spectra of a series of methyl deoxyfluoro-β-d-galactopyranosides and their per-O-acetyl derivatives have been measured. The data obtained can be used as an aid for the interpretation of13C NMR spectra of deoxyfluoro-β-d-galactopyranose-containing oligosaccharides and related substances.

ISSN:0732-8303    

DOI:10.1080/07328308308057877

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Perbenzyl derivatives ofd-glucose,d-mannose,d-galactose,d-xylose,d-ribose andl-arabinose were prepared by treatment of reducing sugars with benzyl bromide in DMSO in the presence of potassium hydroxyde and the composition (α/β, Pyranoside/Furanoside) of the reaction mixtures determined by13C-Nuclear Magnetic Resonance spectroscopy. Most of the per-O-benzyl glycosides were obtained in crystalline form unlike the corresponding methyl per-O-benzyl glycosides. Benzylation ofd-mannose gave almost exclusively penta-O-benzyl-β-d-mannopyranoside (≥ 95%) as cristalline material. Benzylated reducing sugars were further obtained in good yield by acid hydrolysis of above compounds.

ISSN:0732-8303    

DOI:10.1080/07328308308057878

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The formose which was obtained from formaldehyde in the presence of base was a mixture of sugars and sugar alcohols containing over 30 components. The formose reaction has drawn much attention for 122 years from several standpoints; the chemical synthesis of edible carbohydrates from C1compounds, an important process in the recycling of carbon sources during sustained space flights, and as a model for the prebiotic synthesis of monosaccharides. Nevertheless, because of the complexity of this product mixture (Fig. 1b), the formose reaction has not been completely elucidated and the product (so called formose) has not been useful yet. During the long formose history few products were isolated from the formose mixture and identified, except in work from our laboratories.

ISSN:0732-8303    

DOI:10.1080/07328308308057879

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor