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A total synthesis of d-(+)-biotin is described starting from d-(+)-glucosamine using acyliminium chemistry. 相似文献
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Yuchao Li Xuezhao Li Lili Li Bing Xiao Jinguo Wu Hechuan Li Danyang Li Cheng He 《中国化学快报》2021,32(2):735-739
The design and synthesis of a phenoxazine-based metal-organic tetrahedro n(Zn_4L_4) as biomimetic lectin for selectively recognition of glucosamine(GlcN) was reported.Different from the free phenoxazinebased ligand(L),Zn_4L_4 displayed the highest fluorescent intensity enhancement efficiency toward GlcN over other related natural mono-and disaccharides.Fluorescence titration demonstrated a 1:1 stoichiometric host-guest complex was formed with an association constant about 4.03 × 10~4 L/mol.~1H NMR spectroscopic studies confirmed this selectivity resulted from the multiple hydrogen bonding interactions formed between GlcN and Zn_4L_4.The present results suggested that rational arrangement of recognition sites in the confined space of metal-organic cage is crucial for the selectivity toward target guests. 相似文献
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The monosaccharide moieties found in heparin (HP) and heparan sulfate (HS), glucosamine and two kinds of uronic acids, glucuronic and iduronic acids, were efficiently synthesized by use of glucosamine hydrochloride and glucurono-6,3-lactone as starting compounds. In the synthesis of the disaccharide building block, the key issues of preparation of uronic acids (glucuronic acid and iduronic acid moieties) were achieved in 12 steps and 15 steps, respectively, without cumbersome C-6 oxidation. The resulting monosaccharide moieties were utilized to the syntheses of HP/HS disaccharide building blocks possessing glucosamine-glucuronic acid (GlcN-GlcA) or iduronic acid (GlcN-IdoA) sequences. The disaccharide building blocks were also suitable for further modification such as glycosylation, selective deprotection, and sulfation. 相似文献
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Carbohydrate-based low molecular weight gelators are an interesting class of molecules with many potential applications. Previously, we have found that certain esters and carbamates of 4,6-O-benzylidene-α-d-methyl-glucopyranoside are low molecular weight gelators for a variety of solvents, including water. In order to obtain effective and robust sugar-based organogelators and understand the structure and gelation relationship, we extended our studies using 4,6-O-benzylidene-α-d-methyl-2-deoxy-2-amino-glucopyranoside as the headgroup. A series of amides and ureas were prepared from the protected d-glucosamine and the corresponding isocyanates or acid chlorides, in good yields. The self-assembling properties of these compounds were studied in several solvents, including water and aqueous solutions. Comparing to the ester and carbamate derivatives previously prepared from d-glucose, the amides and urea derivatives afforded more robust gels at lower concentrations typically. Most of these compounds were found to be efficient low molecular weight hydrogelators (LMHGs) for aqueous solutions at concentrations lower than 0.5 wt %. The preparation and characterization of these compounds are reported here. 相似文献
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Stacy P. Ali 《Journal of carbohydrate chemistry》2013,32(4):185-196
The order of reactivity of OH and NH groups of glucosamine hydrochloride (GlcNH2.HCl) and N-acetyl glucosamine (GlcNAc) toward benzylation with NaH/BnBr in DMF was investigated. For GlcNH2.HCl, benzyl groups were introduced in the order of N-Bn > N-Bn2 > 1-O-Bn > 6-O-Bn > 4-O-Bn > 3-O-Bn; for GlcNAc, benzyl groups were introduced in the order of 1-O-Bn > 6-O-Bn > 4-O-Bn > 3-O-Bn > N-Bn. A range of partially benzylated 2-N,N′-dibenzyl glucopyranosides and GlcNAc derivatives were obtained in a single step. 相似文献
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Synthesis of a Trisaccharide Related to the Cytotoxic Triterpenoid Saponins Isolated from the Bark of Albizia procera 下载免费PDF全文
Qing‐Chao Liu Tian‐Tian Guo Cong Zhao Jing Sun Wen‐Hong Li 《Helvetica chimica acta》2014,97(3):361-368
Chemical synthesis of a trisaccharide related to the cytotoxic triterpenoid saponins isolated from the bark of Albizia procera has been accomplished through a concise stepwise glycosylation strategy starting from commercially available D ‐xylose, 2‐acetamido‐2‐deoxy‐D ‐glucose and L ‐arabinose. The target trisaccharide was designed with a 4‐methoxyphenyl (MP) aglycone to extend the scope of conversion to suitable glycoconjugates via selective removal of 4‐methoxyphenyl (MP) group. An unexpected phenomenon, i.e., the arabinosyl residue assumed the 1C4 conformation instead of the typical 4C1 form, was observed. Deprotection could restore the normal conformation. 相似文献
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Effective protection of the N-sulfate of glucosamine derivatives with the 2,2,2-trichloroethyl group
Jianfang Chen 《Tetrahedron letters》2008,49(10):1682-1685
The 2,2,2-trichloroethyl (TCE) group was utilized as the first protecting group for N-sulfates (chlorosulfuric acid TCE ester, Et3N, DMAP, DMF). Glycosylation with 3,4,6-tri-O-acetyl-N-trichloroethylsulfuryl-α-d-glucosaminosyl trichloroacetimidate provided the corresponding β-glucosaminosides stereoselectively and in excellent yields. The TCE protection stayed stable under a variety of conditions for the manipulation of other protecting groups, and was readily removable with zinc in the presence of ammonium chloride in methanol. 相似文献
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Cheng-yuan Huang Ning Wang Katsumasa Fujiki Yuji Otsuka Masao Akamatsu Yukari Fujimoto 《Journal of carbohydrate chemistry》2013,32(6):289-298
The N-Troc (2,2,2-trichloroethoxycarbonyl) groups in glucosamine and muramic acid derivatives were removed by treatment with tetrabutylammonium fluoride (TBAF) under mild conditions. The use of Troc protection for the amino group in aminosugars such as glucosamine is increasing the importance for selective and efficient glycosylation, and the cleavage method described here will expand the available opportunities for using the Troc group in the preparation of a variety of glycans. This cleavage is especially advantageous for compounds that are labile or may be decomposed under acidic conditions, strong basic conditions, or reductive conditions. 相似文献