摘要:

This review of the literature on oligosaccharide synthesis tabulates over 700 glycosidic linkages that have been chemically synthesized in the “popular literature” in the year 1994. The “popular literature” consists of the following journals, most frequently used for reporting oligosaccharide synthesis:Acta Chem. Scand., Angew. Chem. Intl. Ed. Engl., Aust. J. Chem., Bioorg. Med. Chem., Bioorg. Med. Chem. Lett., Bull. Chem. Soc. Jpn., Bull. SOC. Chim. Fr., Can. J. Chem., Carbohydr. Res., Carbohydr. Lett., Chem. Ber., Chem. Lett., Chem.-Ztg., Gazz. Chim. Ital., Glycoconjugate J., Glycobiology, Helv. Chim. Acta, Heterocycles, J. Am. Chem. Soc., J. Carbohydr. Chem., J. Chem. Res., J. Chem. Soc. Chem. Commun., J. Chem. Soc. Perkin Trans. I, J. Med. Chem., J . Org. Chem., Liebigs Ann. Chem., Pol. J. Chem., Rec. Trav. Chim. Pays Bas., Synlett, Synthesis, Synth. Commun., Tetrahedron and Tetrahedron Lett.

ISSN:0732-8303    

DOI:10.1080/07328309508005396

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Glycosylation of 2,3,6-tri-O-benzyl-α-D-glucopyranosyl 2,3-di-O-benzyl-4,6-O-benzylidene-α-D-glucopyranoside (5) with α-D-glucopyranosyl, α-maltosyl, and α-maltotriosyl bromides4, 7, and8afforded the β-D-(1→4)-substituted trehalose tri-, tetra-, and pentasaccharides6, 9, and10which were fully characterized by1H NMR spectroscopy. Deprotection gave the free oligosaccharides1, 2, and3.

ISSN:0732-8303    

DOI:10.1080/07328309508005397

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

α,β-(1→4)-Glucans were devised as models for heparan sulfate with the simplifying assumptions that carboxyl-reduction and sulfation of heparan sulfate does not decrease the SMC antiproliferative activity and thatN-sulfates in glucosamines can be replaced byO-sulfates. The target oligo-saccharides were synthesized using maltosyl building blocks. Glycosylation of methyl 2,3,6,2′,3′,6′-hexa-O-benzyl-β-maltoside (1) with hepta-O-acetyl-α-maltosyl bromide (2) furnished tetrasaccharide3which was deprotected to α-D-Glc-(1→4)-β-D-Glc-(1→4)-α-D-Glc-(1→4)-β-D-Glc-(1→OCH3) (5) or, alternatively, converted to the tetrasaccharide glycosyl acceptor (8) with one free hydroxyl function (4‴′-OH). Further glycosylation with glucosyl or maltosyl bromide followed by deblocking gave the pentasaccharide [β-D-Glc-(1→4)-α-D-Glc-(1→4)]2-β-D-Glc-(1→OCH3) (11) and hexasaccharide [α-D-Glc-(1→4)-β-D-Glc-(1→4)2-α-D-Glc-(1→4)-β-D-Glc-(1→OCH3) (14). The protected tetrasaccharide3and hexasaccharide12were fully characterized by1H and13C NMR spectroscopy. Assignments were possible using 1D TOCSY, T-ROESY,1H,1H 2D COSY supplemented by1H-detected one-bond and multiple-bond1H,13C 2D COSY experiments.

ISSN:0732-8303    

DOI:10.1080/07328309508005398

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Modeling the relative reactivity of the hydroxy functions of carbohydrates may be of interest to understand and predict selective synthesis. In the present work, the chemical reactivity of sucrose has been evaluated using semiempirical molecular orbital (AM1 and PM3) frameworks. A simple conformational equilibrium of sucrose consistent with NMR experiments was taken into account. The Potential Electrostatic Surface computed from partial atomic charges failed to provide useful information, in part because of the multiconformational problem. Semiempirical calculations of deprotonation enthalpies (DPEs) could provide a comparative scale for acidity of the various hydroxyl groups. DPE averaging showed that the O-2g hydroxy function is by far the most acidic position of the molecule. These results, which are in good agreement with experimental chemical observations, indicate that intramolecular hydrogen bonds also play a key role on the acidity of the sucrose hydroxyls. The order of acidity of the various hydroxyl groups is O-2g"H-2g≫O-3g"H-3g>O-3f"H-3f>O-1f"H-1f=O-4g"H-4g>O-4f"H-4f≫O-6g"H-6g≫O-6f"H-6f. Despite these encouraging results it should be stressed that the application of such modeling techniques is not yet straightforward, and that the enhanced conformational flexibility of sucrose, including the secondary hydroxyl groups orientation, is still a limiting factor in a complete unravelling of the chemical reactivity of this carbohydrate molecule.

ISSN:0732-8303    

DOI:10.1080/07328309508005399

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Methyl 6-amino-6-deoxy-α-D-glycopyranosides having the D-gluco, D-mannoand D-galactoconfigurations (1a–3a), 2-aminoethanol (4a), 1-amino-1-deoxy-D-glucitol (5a), and 1-amino-1-deoxy-4-O-β-D-glucopyranosyl-D-glucitol (6a) were transformed into the corresponding per-O-acetyl amine hydrochlorides1d–6din excellent yields by using the 2,2-(diethoxycarbonyl)vinyl group for temporary amine protection. Deprotection of the peracetylated enamines1c–6cwas effected with chlorine in chloroform and no O→N acetyl migration occurred when short reaction times were used. Treatment of1d–6dwith thiophosgene resulted in the formation of peracetyl isothiocyanates (1e–6e).

ISSN:0732-8303    

DOI:10.1080/07328309508005400

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Starting from L-fucose, D-glucose and lactose, methylO-[2,3-di-O-benzoyl-4, 6-O-(4-methoxybenzylidene)-β-D-glucopyranosyl]-(1→4)-2,3-di-O-benzoyl-α-L-fucopyranoside and methylO-(2,3,4,6-tetra-O-benzyl-β-D-galactopyranosyl)-(1→4)-O-(2,3,6-tri-O-benzyl-α-D-glucopyranosyl)-(1→4)-O-(methyl 2,3-di-O-benzoyl-β-D-glucopyranosyluronate)-(1→4)-2,3-di-O-benzoyl-α-L-fucopyranoside were synthesized. Removal of protecting groups gave the tetrasaccharide repeating unit of the antigen fromKlebsiellatype-16 in the form of its methyl ester methyl glycoside.

ISSN:0732-8303    

DOI:10.1080/07328309508005401

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The active site of dermatan sulfate (DS) for heparin cofactor II (HCII) was isolated in a fragment obtained by periodate oxidation, borohydride reduction, mild acid hydrolysis, and SE- and SAX-chromatography of beef mucosal and pig skin DS preparations. Characterization by mass spectrometry, one- and two-dimensional NMR spectroscopy, and HPLC analysis of disaccharides, obtained by exhaustive digestion with chondroitinase-ABC, indicates that the fragment has the prevalent structure1, GalNAc-4SO3-[IdoA-2SO3-GalNAc-4SO3]4-R, where R is CH(CH2OH)CH(COO−)-OH.1, is the largest DS fragment thus far isolated containing IdoA2SO3as the only uronic acid. Its lower activity (30%) with respect to the parent polymeric DS is explainable by Tollefsen model, requiring longer polyanionic chains for formation of ternary complex with thrombin.

ISSN:0732-8303    

DOI:10.1080/07328309508005402

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The reaction of 4-O-acetyl-1-deoxy-5,6-O-isopropylidene-2,3-D-erythroand (D-threo)-hexodiulose with aminoguanidine (guanylhydrazine) was investigated at pH 7.0 and 37°C. The two dicarbonyl compounds reacted rapidly to give 6-methyl-5-substituted triazine derivatives, which were fully characterized. The compounds were deblocked in a stepwise manner to give, first the de-O-acetylated compounds and then (by removal of the isopropylidene groups) the free triazine derivatives which were fully characterized (GLC/MS, NMR and elemental analyses).

ISSN:0732-8303    

DOI:10.1080/07328309508005403

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Synthesis of new cyanoethylated compounds and carboxylic acids derived from sucrose, methyl D-glucopyranoside, methyl D-fructopyranoside and methyl D-fructofuranoside are described. Basic hydrolysis of these cyanoethylated compounds to the corresponding amides and carboxylates and acidic alcoholysis to the corresponding methyl esters are discussed.

ISSN:0732-8303    

DOI:10.1080/07328309508005404

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The reaction of acetylaminoacetonitrile with penta-O-benzoyl-α-D-glucopyranose in dichloromethane-nitromethane, in a 1:1 stoichiometric proportion, catalysed by stannic chloride, gave a nitrilium salt that, after hydrolysis, afforded the correspondingN-acyl glycosylamine and a mixture of several compounds originating from different competitive reactions. Among these compounds,N-benzoyl-3,5,6-tri-O-benzoyl-β-D-glucofuranosyl amine, tetra-O-benzoyl-D-glucopyranose, and octa-O-benzoyl-β-D-glucopyranosyl-(1→1)-α-D-glucopyranoside (octa-O-benzoyl-α,β-trehalose) were identified.

ISSN:0732-8303    

DOI:10.1080/07328309508005405

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor