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1.
Synthesis of Disaccharide Nucleosides by the O‐Glycosylation of Natural Nucleosides with Thioglycoside Donors
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Prof. Shin Aoki Taketo Fukumoto Taiki Itoh Masayuki Kurihara Shigeto Saito Shin‐ya Komabiki 《化学:亚洲杂志》2015,10(3):740-751
Disaccharide nucleosides constitute an important group of naturally‐occurring sugar derivatives. In this study, we report on the synthesis of disaccharide nucleosides by the direct O‐glycosylation of nucleoside acceptors, such as adenosine, guanosine, thymidine, and cytidine, with glycosyl donors. Among the glycosyl donors tested, thioglycosides were found to give the corresponding disaccharide nucleosides in moderate to high chemical yields with the above nucleoside acceptors using p‐toluenesulfenyl chloride (TolSCl) and silver triflate (AgOTf) as promoters. The interaction of these promoters with nucleoside acceptors was examined by 1H NMR spectroscopic experiments. 相似文献
2.
Stereoretentive Palladium‐Catalyzed Arylation,Alkenylation, and Alkynylation of 1‐Thiosugars and Thiols Using Aminobiphenyl Palladacycle Precatalyst at Room Temperature
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Alexandre Bruneau Dr. Maxime Roche Dr. Abdallah Hamze Dr. Jean‐Daniel Brion Dr. Mouad Alami Dr. Samir Messaoudi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8375-8379
A general and efficient protocol for the palladium‐catalyzed functionalization of mono‐ and polyglycosyl thiols by using the palladacycle precatalyst G3‐XantPhos was developed. The C?S bond‐forming reaction was achieved rapidly at room temperature with various functionalized (hetero)aryl‐, alkenyl‐, and alkynyl halides. The functional group tolerance on the electrophilic partner is typically high and anomer selectivities of thioglycosides are high in all cases studied. New sulfur nucleophiles such as thiophenols, alkythiols, and thioaminoacids (cysteine) were also successfully coupled to lead to the most general and practical method yet reported for the functionalization of thiols. 相似文献
3.
Tomonari Tanaka Genri Inoue Shin‐Ichiro Shoda Yoshiharu Kimura 《Journal of polymer science. Part A, Polymer chemistry》2014,52(24):3513-3520
Polyacrylamides having pendant thioglycosides were successfully synthesized from thioglycosidic monomers that were readily prepared by one‐pot method without any protection of the hydroxy groups on the starting free saccharides. The glycomonomers were synthesized by the direct synthesis of thioglycosides using 2‐chloro‐1,3‐dimethylimidazolinium chloride and 4‐aminobenzentiol, and the following acrylamidation. They were co‐polymerized with acrylamide into glycopolymers by reversible addition‐fragmentation chain transfer polymerization using a trithiocarbonate derivative as a chain transfer agent. The gold nanoparticles and gold‐coated quartz crystal microbalance sensor immobilized with the thiol‐terminated glycopolymers exhibited high affinity for the corresponding lectins due to multivalent interaction between saccharides and protein in aqueous solution. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3513–3520 相似文献
4.
Synthesis,Antiviral, and Antimicrobial Activity of N‐ and S‐Alkylated Phthalazine Derivatives
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Ahmed H. Moustafa Hassan A. El‐Sayed Rasha A. Abd El‐Hady Abdelfattah Z. Haikal Maher El‐Hashash 《Journal of heterocyclic chemistry》2016,53(3):789-799
A series of N‐alkylphthalazinone were synthesized by the reaction of phthalazin‐1(2H)‐one derivatives 1a , 1b , 1c with alkylating agents namely, propargyl, allyl bromide, epichlorohydrin, 1,3‐dichloro‐2‐propanol, 4‐bromobutylacetate, and 1‐(bromomethoxy)ethyl acetate to give the corresponding N‐alkylphthalazinone 2a , 2b , 2c , 3a , 3b , 3c , 5a , 5b , 5c , 6a , 6b , 6c , 7a , 7b , 7c , and 9a , 9b , 9c . Alkylation of phthalazin‐1(2H)‐thione to give a series from S‐alkylphthalazine 12 , 13 , 14 and thioglycosides 15 and 17 was performed. Deprotection of compounds 7a , 7b , 7c , 9a , 9b , 9c , 15 , and 17 resulted in the formation of the corresponding products 8a , 8b , 8c , 10a , 10b , 10c , 16 , and 18 . The structure of newly synthesized compounds was assigned by IR, 1H, 13C NMR, and elemental analysis. Some of these compounds were screened for antiviral and antimicrobial activity. 相似文献
5.
Galal H. Elgemeie Wafaa A. Zaghary Kamelia M. Amin Tamer M. Nasr 《Journal of carbohydrate chemistry》2013,32(6):373-378
The preparation of a new class of acrylamide thioglycosides via one‐pot reaction of the potassium 2‐cyanoethylene‐1‐thiolate salts with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐gluco‐ and galactopyranosyl bromides has been studied. The E‐configuration of these thioglycosides was proven by their transformations to the corresponding 5‐aminopyrazoles. 相似文献
6.
Tetsuya Kajimoto Yuichi Ishioka Takahiro Katoh 《Journal of carbohydrate chemistry》2013,32(8-9):469-495
p‐Dodecylbenzenethiol (1) and p‐octyloxybenzenethiol (2) were synthesized as new odorless benzenethiols. Moreover, preparation of novel 1‐thioglycosides using 1 and 2 as well as their application for glycosylation reactions was performed. As a result, it was found that these 1‐thio‐glycosides were excellent glycosyl donors, and especially 2‐thio‐sialoside prepared from 1 and 2 afforded the best result to date in terms of α‐ and β‐selectivity in the sialylation where only the single C‐3 hydroxyl group of acceptor D‐galactopyranoside was free. All procedures from the preparation of thioglycosides to glycosylation reaction were attainable under completely odorless conditions. 相似文献
7.
Regioselective deprotection of the monosaccharide‐bearing thiocyanomethyl group at the anomeric position monitored by reversed‐phase HPLC method
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Qais Abualassal Khaldun M. Al Azzam Jamal A. Jilani 《Biomedical chromatography : BMC》2016,30(9):1416-1422
In the current work, the investigation and development of a chemo‐enzymatic approach for the synthesis of neo‐glycoproteins have been studied. This strategy is based on the regioselective enzymatic hydrolysis of peracetylated monosaccharide, functionalized at the anomeric position (C1) as 1‐thio‐(S‐cyanomethyl) group, a precursor of the 2‐ iminomethoxyethyl thioglycosides‐linker for protein glycosylation, catalyzed by immobilized enzymes to obtain selectively monodeprotected compounds. The use of this activation in C1 is the most frequently used strategy for glycoprotein preparation. The selected biocatalysts are the lipase from Candida rugosa and the acetyl xylan esterase from Bacillus pumilus. A reversed‐phase high‐performance liquid‐chromatographic (HPLC) method for monitoring the regioselective deprotection reaction has been developed. The developed HPLC method was used as a fingerprint to follow the hydrolysis of substrate 1 to substrate 1a and to determine its purity and yield. Moreover, the obtained compound was further purified by flash chromatography. The obtained compound 1a was further characterized using 1H, 13C NMR, correlation spectroscopy (COSY) and heteronuclear multiple bond correlation. The resulting product can be used as an intermediate for the preparation of di‐ and more complex oligosaccharides aimed at protein conjugation. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
8.
Wael A. El‐Sayed Ibrahim F. Nassar Adel A.‐H. Abdel‐Rahman 《Journal of heterocyclic chemistry》2011,48(1):135-143
New 1,2,4‐triazine and their derived 1,2,4‐triazolo[3,4‐b][1,2,4]triazine derivatives were synthesized starting from 5,6‐diphenyl‐1,2,4‐triazine‐3‐thiol. Furthermore, the corresponding 1,2,4‐triazolo[3,4‐b][1,2,4]‐triazine thioglycosides and acyclic C‐nucleoside analogs were synthesized. The newly synthesized compounds were evaluated for their antitumor activity and some of them showed high inhibition activities. J. Heterocyclic Chem., 2011. 相似文献
9.
An efficient one‐pot protocol for the direct preparation of thioglycosides starting from unprotected reducing sugars via S‐glycosyl isothiouronium salts is reported. In this one‐pot methodology, BF3 · OEt2 has been used as a general catalyst for both per‐O‐acetylation of sugars and conversion of sugar per‐O‐acetates into S‐glycosyl isothiouronium salts, which was allowed to react with alkylating agents in the presence of a base to furnish thioglycosides in excellent yield. 相似文献
10.
《中国化学会会志》2017,64(5):464-473
Thioglycosylation of 1‐hydroxyl glycosides catalyzed by in situ‐generated AlI3 from elemental aluminium and molecular iodine has been developed. This method provides an alternative route to access anomeric thioglycosides without the use of hazard Lewis acidic activators or per‐modified activated thiol sources. The major advantages of this dehydrative procedure are environmental friendly, ease of operation, high anomeric diastereoselectivity, and mild reaction conditions. 相似文献
11.
《化学:亚洲杂志》2017,12(24):3114-3118
A controllable method for the functionalization of XantPhos Pd‐G3 precatalyst with thiosugars and thiols has been established. Under mild and operationally simple reaction conditions through just mixing of precatalyst and thiosugars (α‐ or β‐mono‐, di‐ and poly‐thiosugar derivatives) in water at 25 °C for 20 min, a series of 1‐aminobiphenyl thioglycosides that are difficult to synthesize by classical methods has been synthesized in very high yields. 相似文献
12.
《Journal of carbohydrate chemistry》2013,32(4-6):415-424
An improved protocol for the large‐scale production of 1‐benzenesulfinyl piperidine and other sulfinamides is described. It is demonstrated that 1‐benzenesulfinyl pyrrolidine and N,N‐diethyl benzenesulfinamide function analogously to 1‐benzenesulfinyl piperidine in the trifluoromethanesulfonic anhydride‐mediated activation of thioglycosides, and that their less crystalline nature enables them to be used at ?78°C as opposed to the ?60°C required to keep 1‐benzenesulfinyl piperidine in solution. N,N-Dicyclohexyl benzenesulfinamide does not activate thioglycosides in combination with trifluoromethanesulfonic anhydride, which is attributed to its greater steric bulk. 相似文献
13.
A series of thiadiazole‐based thioglycosides were synthesized as SGLT2 inhibitors from D‐glucose, D‐galactose and a variety of phenylacetic acids via a convenient protocol in 8 steps and evaluated in vivo with an oral glucose tolerance test (OGTT), and 5‐benzyl‐1,3,4‐thiadiazol‐2‐yl 1‐thio‐β‐D‐glucopyranoside ( 1a ) was the most efficacious to suppress the blood glucose excursion during OGTT. 相似文献
14.
Eman M. Flefel Waled A. Tantawy Wael A. El‐Sayed Hayam H. Sayed Nahed M. Fathy 《Journal of heterocyclic chemistry》2013,50(2):344-350
New substituted pyrazole, thiazole, and 1,2,4‐triazole derivatives were synthesized. The sugar hydrazones, their acetylated derivatives as well as their derived acyclic C‐nucleoside analogs, and the thioglycosides of the 1,2,4‐traizole derivatives were also prepared. The antitumor activity of some of the synthesized compounds were studied, and a number of the tested compounds showed significant activities. 相似文献
15.
New glycosyl donors have been developed that contained several para‐substituted O‐aryl protecting groups and their stereoselectivity for the glycosylation reaction was evaluated. A highly β‐selective glycosylation reaction was achieved by using thioglycosides that were protected by 4‐nitrophenyl (NP) groups, which were introduced by using the corresponding diaryliodonium triflate. Analysis of the stereoselectivities of several glycosyl donors indicated that the β‐glycosides were obtained through an SN2‐type displacement from the corresponding α‐glycosyl triflate. The NP group could be removed by reduction of the nitro group and acylation, followed by oxidation with ceric ammonium nitrate (CAN). 相似文献
16.
《Tetrahedron: Asymmetry》2005,16(2):321-335
The treatment of various glycosyl acceptors, each containing a reactive thiol group, with the appropriate glycosyl donor and a glycoside hydrolase or glycosynthase, failed to yield any thioglycosides––only the products of O-glycosylation were formed. However, thioglycosides were formed when a thioglycoligase was used to mediate the reaction between acceptor and donor. In fact, pyranose acceptors possessing a thiol group at C3, C4 or C6 (but not C2) were all capable of conversion into thioglycosides. Some comment is given regarding the mechanism of the various processes. 相似文献
17.
Samira Escopy Dr. Yashapal Singh Prof. Dr. Keith J. Stine Prof. Dr. Alexei V. Demchenko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):354-361
Our group has previously reported that 3,3-difluoroxindole (HOFox) is able to mediate glycosylations via intermediacy of OFox imidates. Thioglycoside precursors were first converted into the corresponding glycosyl bromides that were then converted into the OFox imidates in the presence of Ag2O followed by the activation with catalytic Lewis acid in a regenerative fashion. Reported herein is a direct conversion of thioglycosides via the regenerative approach that bypasses the intermediacy of bromides and eliminates the need for heavy-metal-based promoters. The direct regenerative activation of thioglycosides is achieved under neutral reaction conditions using only 1 equiv. NIS and catalytic HOFox without the acidic additives. 相似文献
18.
Determination of the Influence of Side‐Chain Conformation on Glycosylation Selectivity using Conformationally Restricted Donors
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Dr. Suresh Dharuman Prof. Dr. David Crich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(13):4535-4542
The synthesis of a series of conformationally locked mannopyranosyl thioglycosides in which the C6?O6 bond adopts either the gauche,gauche, gauche,trans, or trans,gauche conformation is described, and their influence on glycosylation stereoselectivity investigated. Two 4,6‐O‐benzylidene‐protected mannosyl thioglycosides carrying axial or equatorial methyl groups at the 6‐position were also synthesized and the selectivity of their glycosylation reactions studied to enable a distinction to be made between steric and stereoelectronic effects. The presence of an axial methoxy group at C6 in the bicyclic donor results in a decreased preference for formation of the β‐mannoside, whereas an axial methyl group has little effect on selectivity. The result is rationalized in terms of through‐space stabilization of a transient intermediate oxocarbenium ion by the axial methoxy group resulting in a higher degree of SN1‐like character in the glycosylation reaction. Comparisons are made with literature examples and exceptions are discussed in terms of pervading steric effects layered on top of the basic stereoelectronic effect. 相似文献
19.
Stereoselective Synthesis of α‐3‐Deoxy‐D‐manno‐oct‐2‐ulosonic Acid (α‐Kdo) Glycosides Using 5,7‐O‐Di‐tert‐butylsilylene‐Protected Kdo Ethyl Thioglycoside Donors
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Jia‐Sheng Huang Wei Huang Xue Meng Xin Wang Peng‐Cheng Gao Prof. Dr. Jin‐Song Yang 《Angewandte Chemie (International ed. in English)》2015,54(37):10894-10898
An efficient methodology for the synthesis of α‐Kdo glycosidic bonds has been developed with 5,7‐O‐di‐tert‐butylsilylene (DTBS) protected Kdo ethyl thioglycosides as glycosyl donors. The approach permits a wide scope of acceptors to be used, thus affording biologically significant Kdo glycosides in good to excellent chemical yields with complete α‐selectivity. The synthetic utility of an orthogonally protected Kdo donor has been demonstrated by concise preparation of two α‐Kdo‐containing oligosaccharides. 相似文献
20.
Ying‐Ling Liu Chuan‐Shao Wu Yie‐Shun Chiu Wen‐Hsuan Ho 《Journal of polymer science. Part A, Polymer chemistry》2003,41(15):2354-2367
A novel epoxy system was developed through the in situ curing of bisphenol A type epoxy and 4,4′‐diaminodiphenylmethane with the sol–gel reaction of a phosphorus‐containing trimethoxysilane (DOPO–GPTMS), which was prepared from the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) with 3‐glycidoxypropyltrimethoxysilane (GPTMS). The preparation of DOPO–GPTMS was confirmed with Fourier transform infrared, 1H and 31P NMR, and elemental analysis. The resulting organic–inorganic hybrid epoxy resins exhibited a high glass‐transition temperature (167 °C), good thermal stability over 320 °C, and a high limited oxygen index of 28.5. The synergism of phosphorus and silicon on flame retardance was observed. Moreover, the kinetics of the thermal oxidative degradation of the hybrid epoxy resins were studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2354–2367, 2003 相似文献