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1.
A wide range of symmetrical and unsymmetrical glycosyl disulfides is synthesized with focus on the use of α-glycosyl thiols. Oxidation of α-glycosyl thiols with iodine leads to symmetrical α,α-glycosyl disulfides, while unsymmetrical disulfides are readily synthesized from α- and β-glycosyl thiols under the action of DDQ. Thus, glycosyl disulfides containing at least one α-glycosidic linkage are made available. 相似文献
2.
Hiroshi Tanaka 《Tetrahedron letters》2004,45(7):1433-1436
We describe the one-pot synthesis of core 2 class branched oligosaccharides initiated by chemo-selective glycosylation of silyl ether. Glycosylation of 6-O-silyl-4-benzyl-2-azido-thiogalactoside with glycosyl fluoride provided selectively 6-glycosylated thioglycoside without both O-glycosylation at the 3 position and S-glycosylation. Subsequent coupling of galactosyl fluoride and amino acids afforded the protected branched oligosaccharides in good yields. 相似文献
3.
High yielding synthesis of six- and five-membered N-substituted iminosugar glycosides and of five-membered iminosugar thioglycosides by nucleophilic opening of both new and previously described N-diethoxycarbonylvinyl anhydroiminosugar derivatives (glycosyl donors) with primary alcohols, primary thiols, and thiophenol (glycosyl acceptors) is reported. The reactions are highly stereoselective, with anomeric ratios better than 4:1. 相似文献
4.
Xiangming Zhu 《Tetrahedron letters》2006,47(45):7935-7938
The 4-monomethoxytrityl (MMTr) group was introduced in high yields to anomeric sulfhydryl functions using commercially available MMTrCl. Significantly, it is stable to a variety of reaction conditions, including acids and bases, and is removable under very mild acidic conditions, which are compatible with the presence of a number of other acid-labile hydroxyl protecting groups. The successful preparation of seven glycosyl thiols indicates that MMTr has potential application for the synthesis of complex 1-thiosugars. 相似文献
5.
A high-yielding, one-pot methodology for preparing unsymmetrical glycosyl disulfides derived from sugar, alkyl/aryl or cysteine thiols is reported using 1-chlorobenzotriazole (BtCl) as the oxidant. The highlight of the method is the low temperature of coupling (−78 °C) as well as the in situ trapping of the sulfenyl intermediate, which ensures that no homodimer of R1SH (R1SSR1) is formed. The coupling efficiency is independent of sugar type, thiol position in the sugar, sugar-protecting groups, and the various products serve to illustrate the rapid synthetic access to a number of model systems in glycobiology. 相似文献
6.
The PhSeOTf promoted glycosylations of various glycosyl acceptors with mannosyl pentenoates and glucosyl pentenoates as glycosyl donors afforded corresponding disaccharides in high yields. And the present glycosyl pentenoates/PhSeOTf method showed that the complete -selective mannosylation of secondary alcohol acceptors was achieved with 2,3,4,6-tetra-O-benzyl-d-mannopyranosyl pentenoate to give -disaccharides in good yields. 相似文献
7.
Glycosyl trifluoroacetimidates have been disclosed to be effective glycosyl donors for the synthesis of nucleosides; the present N-glycosylation protocol requires only a catalytic amount of TMSOTf as promoter and proceeds smoothly at room temperature. 相似文献
8.
A novel way of synthesizing unsymmetrical disulfides from thiols with DDQ is presented here. This procedure ran in a straightforward manner to give high product yields. Unsymmetrical disulfides were directly synthesized from the corresponding mixture of thiols in equimolar amounts under mild conditions. 相似文献
9.
A variable group of unsymmetric disulfides was prepared under mild reaction conditions and in high yields through the reaction of symmetric disulfides with sulfuryl chloride followed by treatment with thiols in the presence of water. 相似文献
10.
Geetanjali Agnihotri 《Tetrahedron letters》2005,46(47):8113-8116
A very fast and selective oxidation of thioglycosides to glycosyl sulfoxides has been achieved using KF/m-CPBA in CH3CN-H2O. This protocol has many advantages compared to the currently available methodologies for this transformation in terms of selectivity, yield, reaction time, control of temperature, etc. The yields obtained were excellent in all cases. 相似文献
11.
We have prepared glycosyl type phosphonates via hetero Diels-Alder (HDA) reactions of acyl phosphonates with electron rich dienes. HDA reactions of acyl phosphonates with Danishefsky’s diene required thermal activation to yield the desired dihydropyranones in good yield (70-91%). The reactions with Brassard’s diene involved Lewis acid promotion to yield the corresponding lactones, though in moderate yield (33-69%). 相似文献
12.
Yang Xu Qian Zhang Ying Xiao Pinru Wu Wei Chen Zejin Song Xiong Xiao Lingkui Meng Jing Zeng Qian Wan 《Tetrahedron letters》2017,58(24):2381-2384
Practical synthetic methods to latent disarmed S-2-(2-propylthio)benzyl (SPTB) glycosides for interrupted Pummerer reaction mediated glycosylation have been discovered. Among them, both coupling reaction of PTB-Cl with glycosyl thiols and BF3·OEt2 promoted reaction of peracylated glycosides with PTB-SH produced peracylated SPTB glycosides in large scales and with high efficiency. 相似文献
13.
香草酸糖酯的合成研究 总被引:3,自引:0,他引:3
香草酸(4-羟基-3-甲氧基苯甲酸)广泛存在于胡黄连、高丽参、蜂胶等中药材中。它具有较强的抗氧化、抗菌活性[1,2],是良好的混合型酪氨酸酶抑制剂。闫军等通过实验证明具有C6结构且对位具有极性基团的苯酚及其衍生物是非常好的酪氨酸酶抑制剂[3],而具有C6-C3骨架的二酚及其衍生物不具有抑制酪氨酸酶的作用。B iro等[4,5]发现香草酸可诱使肥大细胞和神经胶质瘤细胞摄取钙,这与香草酸对DRG(脊髓背根神经节dorsal root ganglion)神经元的作用相似。N ish-ikawa等在对脂肪酸的糖基酯进行系统的研究中发现一些糖酯类化合物具有广泛的生物活性,… 相似文献
14.
A practical and efficient synthesis of phosphatidylinositol pentam annoside (PIM5) was achieved based on a five-component one-pot sequential glycosylation protocol with exclusive regio- and stereo-selectivity. 相似文献
15.
《Tetrahedron letters》2017,58(3):218-222
We report herein a one-pot synthesis of unsymmetrical disulfides with trichloroisocyanuric acid (TCCA) as an oxidant. Under facile conditions, aromatic-aromatic disulfides and aromatic-aliphatic disulfides were synthesized in good to excellent yields even without base. For the construction of the challenging aliphatic-aliphatic disulfides, good yields of the desired products were also obtained with slightly modified conditions. Additionally, the reactions demonstrated a wide range of substrate scope, very short reaction time (<5 min), and convenient procedures. 相似文献
16.
Serena Traboni Federica Liccardo Emiliano Bedini Maddalena Giordano Alfonso Iadonisi 《Tetrahedron letters》2017,58(18):1762-1764
Glycosyl chlorides, useful as glycosyl donors in glycoside synthesis and precursors in organic synthesis, can be easily prepared under solvent-free conditions by exposing a sugar hemiacetal to an equimolar mixture of PPh3 and hexachloroacetone at 70 °C. The reaction affords products in high yields and short times, and is tolerant of a wide range of commonly adopted protecting groups. 相似文献
17.
A new synthesis of unsymmetrical disulfides is described. The reaction of a thiol R1SH with 1-chlorobenzotriazole (BtCl) at -78 degrees C in DCM affords a high-yielding conversion to R1SBt without appreciable formation of the symmetrical disulfide R1SSR1. R1SBt is then reacted with R2SH to form the unsymmetrical disulfide in a one-pot sequence with green character that avoids the use of toxic and harsh oxidizing agents. The methodology has been developed for synthesis of various types of disulfides. 相似文献
18.
We present here a convenient synthesis of the truncated sphingoid iodide 15 from d-galactose, in which Mitsunobu reaction was utilized to retrieve successfully an unwanted intermediate, thereby increasing greatly the synthetic efficiency. Subsequent reaction of 15 with the pre-prepared α-galactosyl thiol 16 led smoothly to the desired thioglycoside 17 in good yield, from which the catabolically stable thioglycoside analogs of OCH 4 and 22 were synthesized. 相似文献
19.
Shiyang Xu Wei Zhang Caiyi Li Yanjing Li Hongxin Zeng Prof. Yingwei Wang Yang Zhang Prof. Dawen Niu 《Angewandte Chemie (International ed. in English)》2023,62(16):e202218303
We herein report a method that enables the generation of glycosyl radicals under highly acidic conditions. Key to the success is the design and use of glycosyl sulfinates as radical precursors, which are bench-stable solids and can be readily prepared from commercial starting materials. This development allows the installation of glycosyl units onto pyridine rings directly by the Minisci reaction. We further demonstrate the utility of this method in the late-stage modification of complex drug molecules, including the anticancer agent camptothecin. Experimental studies provide insight into the reaction mechanism. 相似文献
20.
Tetrabutylammonium hydrogen sulfate catalyzed eco-friendly and efficient synthesis of glycosyl 1,4-dihydropyridines 总被引:1,自引:0,他引:1
Neetu Tewari 《Tetrahedron letters》2004,45(49):9011-9014
An efficient and eco-friendly synthesis of glycosyl 1,4-dihydropyridines has been achieved by a three-component reaction of β-keto esters or ketones, enamines and glycosyl aldehydes in the presence of tetrabutylammonium hydrogen sulfate as catalyst in diethylene glycol. 相似文献