摘要:

Various 4-deoxy-α or β-erythroorthreo-pentopyranoses aminated on position 1 [6 and 19]. 2 [38] or 3 [9, 22, 23, 24, 32and35] were synthesised from 2-methoxy-5,6-dihydro-2H-pyran [1] and methyl 2,3-anhydro-4-deoxy-α and β-DL-erythro-pentopyranoside [11]. Different reactions were investigated including azidation.cis-oxyamination, epimine formation and oxirane aminolysis. All these amino sugars were converted into their chloroethylureido derivatives.

ISSN:0732-8303    

DOI:10.1080/07328308808057547

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The distribution of methyl groups in methylcelluloses (DS 1.7) has been determined. The partially methylated monosaccharides obtained on complete hydrolysis of methylcellulose were converted into alditols by reduction. They were identified as their acetates or trimethylsilyl ethers by gas-liquid chromatography-mass spectrometry and quantified by gas-liquid chromatography. In addition,13C-nuclear magnetic resonance spectra of native and hydrolyzed methylcelluloses as well as the partially methylated alditols obtained by hydrolysis and reduction were analyzed. The main glucose methyl ethers obtained were in decreasing order 2,6-, 2,3,6-, 2-, 6-, and 2,3-. The 2-and 6-positions were occupied by methyl groups in 70.0 and 61.5%, respectively, while the 3-position contained only 37.4%. The GLC-MS method gave a more accurate determination of the distribution of methyl groups in methylcellulose compared to NMR spectroscopy.

ISSN:0732-8303    

DOI:10.1080/07328308808057548

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Starting fromD-gluco-andD-mannofuranurono-6,3-lactone, respectively, one enantiomer each of the diastermeric methyl 2-O-thoxy-carbonylhexofuranosidurnon-6,3-lactones was prepared by making use of regioselective esterification and configurational inversion at C-5 via triflates.

ISSN:0732-8303    

DOI:10.1080/07328308808057549

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Methyl (methyl α-D-(9a), α-(9b), β-D-(10a), and β-L-(10b) idopyranosid)uronates were synthesized frommyo-inositol. Baeyer-Villiger oxidation of the optically resolved inosose derivatives (3a and 3b) proceeded regioselectively to afford 4a and 4b in high yields, respectively. Ring-opening of the 7-membered hemiacetal-lactones (4a and 4b) with acid and subsequent deprotection gave the title compounds.

ISSN:0732-8303    

DOI:10.1080/07328308808057550

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

1, 3, 4, 6-Tetra-O-acetyl-2-deoxy-2-fluoro-β-D-galactopyranoside is a key intermediate in the synthesis of phenyl-2-fluoro-2-deoxy-α-D-galactopyranoside which is used in the studies of the inhibitoty activities of α-2-L-fucosyl transferase. Crystals of the title compound (C14H1909F) are triclinic, space group P1, with cell dimensions a=7.679(1), b=9.933(1), c=11.458(2)A0, α=89.31(1), β=72.83(1), γ=86.49(1)°, V=833.5å3, Z=2 (two independent molecules in the unit cell), F.W. 351.3, Dobs= 1.39 g/c.c, Dcalc= 1.401 g/c.c, CAD-4 diffractometer data (3533 reflections, 2483 > 3ρ) and final R = 0.048. The sugars of both the independent molecules have chair conformations with C(3) and 0(1) deviating by 0.64 and-0.66Å in one molecule and C(2) and C(5) deviating by 0.70 and-0.69Å in the other molecule from the best plane involving the other four atoms of the pyranose ring. The conformation across C(5)-C(6) is gauche-trans in both molecules. The acetyl groups take up the preferred trans conformation across the C-O bond.

ISSN:0732-8303    

DOI:10.1080/07328308808057551

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Starting with methyl 2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (1), the isomeric methyl 2-amino-2-deoxy-α-D-glucopyranoside 3-, 4-, and 6-sulfates have each been prepared by sulfation of suitably blocked intermediates. Tritylation and acetylation of1followed by detritylation gave methyl 3,4-di-0-acetyl-2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (3), having a free 6-hydroxyl group. Base catalyzed 0–4→0–6 acetyl migration provided the corresponding 3,6 di-O-acetyl derivative (4) posessing a free 4-hydroxyl group. Preparation of methyl 4,6-0-benzylidene-2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (9) provided the intermediate bearing a free 3-hydroxyl group.0-sulfation of3,4, and9was effected with the pyridine sulfur trioxide complex in dry pyridine.

ISSN:0732-8303    

DOI:10.1080/07328308808057552

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Easily accessible benzyl 2,3-O-isopropylidene-α-D-mannofuranoside (1) was converted in six steps into benzyl 2,3-O-isopropylidene-5-N-benzyl-5-deoxy-6-O-benzyl-α-D-mannofuranoside or benzyl 2,3-O-isopropylidene-5-azido-5-deoxy-6-O-benzyl-α-D-mannofuranoside. Both compounds afforded, after hydrogenolysis and acidolysis, 1-deoxymannojirimycin in an overall yield of 38% based on 1.

ISSN:0732-8303    

DOI:10.1080/07328308808057553

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Benzyl 2,3-anhydro-4-azido-4-deoxy-α-L-ribopyranoside (7), an intermediate for the synthesis of Prumycin was synthesized in 72% yield in seven steps from D-arabinose. Ammonolysis of7followed byN-protection with the benzyloxycarbonyl group gave benzyl 4-azido-2-(benzyloxycarbonyl)amino-2,4-dideoxy-α-L-arabinopyranoside (8), which was easily converted to Prumycin.

ISSN:0732-8303    

DOI:10.1080/07328308808057554

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The preparation of fourRh. VannieliiLipid A analogues (i.e. compounds 22, 23, 30 and 33) is described. Non-neighbouring group supported introduction of the β-glycosidic linkages was performed by coupling the mannopyranosyl bromide 2 and the 2-azido-2-deoxy-glucopyranosyl bromides 10 and 13 with the suitably protected glycosyl acceptors 3, 4 and 5 in the presence of a heterogeneous silver catalyst, to give compounds 6, 7, 14 and 24, respectively. Selective removal of the ally1 group and reduction of the azido functions followed by several O,N-acylation steps afforded, after complete deblocking, the tri-and disaccharideRh. VannieliiLipid A analogues 22, 23, 30 and 33.

ISSN:0732-8303    

DOI:10.1080/07328308808057555

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

3,6-Di-O-methyl-D-glucose, the non-reducing terminal sugar of the phenolic glycolipid-I, elaborated byMycobacterium leprae, has been synthesized by a simple procedure and in high yield. 3-O-Methyl-D-glucose was converted to the corresponding benzyl glycoside and then tosylated to give benzyl 3-O-methyl-6-O-tosyl-β-D-glucopyranoside. Displacement of tosyl group with sodium methoxide followed by debenzylation afforded 3,6-di-O-methyl-D-glucose in high yield. Condensation of the acetobromo derivative of 3,6-di-O-methyl-D-glucose with 8-ethoxycarbonyloctanol gave 8-ethoxycarbonyloctyl 2,4-di-O-acety 1–3, 6-di-O-methy 1-β-D-glucopyranoside. This was then deacetylated, converted to hydrazide, and finally coupled to bovine serum albumin via the acyl azide intermediate. The neo-glycoprotein containing the 3,6-di-O-methyl-β-D-glucopyranosyl group is useful for serodiagnosis of leprosy.

ISSN:0732-8303    

DOI:10.1080/07328308808057556

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor