共查询到20条相似文献,搜索用时 15 毫秒
1.
《Nucleosides, nucleotides & nucleic acids》2013,32(5-8):1411-1413
Abstract Dialkyl(cyanomethyl)ammonium salts 1 were synthesized and used as a novel class of activators for the stereospecific condensations of diastereopure nucleoside 3′-O-oxazaphospholidines with a nucleoside. This new oxazaphospholidine method could efficiently produce both (Rp)- and (Sp)-dinucleoside phosphorothioates. 相似文献
2.
Abstract Enantiomerically pure novel nucleosides having unusual branched sugars were synthesized in a stereospecific manner from a common chiral pool of (S, S)-1,4-bis(benzyloxy)-2,3-epoxybutane and evaluated for antiviral activity. 相似文献
3.
Ibrahim A. I. Ali 《Nucleosides, nucleotides & nucleic acids》2013,32(3):129-140
A series of quinoxaline azido reverse nucleosides 3a-c and their O-regioisomers 4a-c was prepared by reaction of quinoxaline 1a-c with 3-azido-3-deoxy-1,2-O-isopropylidene-5-p-toluenesulfonyl-D-ribofuranose (2) in the presence of sodium hydride. Structure modification of these interesting structures includes reduction and the subsequent acetylation reactions to give quinoxaline amino and acetyl amino reverse nucleosides and their O-regioisomers. 相似文献
4.
Jean M. J. Tronchet Imre Kovacs Françoise Barbalat-Rey Naz Dolatshahi 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):337-347
Abstract TSAO analogues, 2′,5′-O-bis-TBDMS uridine-3′-spiro-3′-isoxazolidin-5′-one (9) and its thymidine congener 10, as well as model spiro sugar derivatives (3 and 4) have been prepared from the corresponding nitrones through a stereospecific tandem nucleophilic attack. Compounds 9 and 10 which are bioisosters of TSAO-U and T respectively but which lack an amino group on the spiro ring, were found inactive against both HIV-1 and HIV-2. 相似文献
5.
Yoshiaki Noma Seiichi Nonomura Heiichi Sakai 《Bioscience, biotechnology, and biochemistry》2013,77(9):1637-1642
As a part of series on the biochemical reduction of terpenes, the conversion of (?)-carvotanacetone (I) and (+)-carvotanacetone (II) by Pseudomonas ovalis, strain 6–1, has been studied.By the action of the microorganism, I was reduced to give (+)-carvomenthone (III), (+)-neocarvomenthol (IV), and (?)-carvomenthol (V), whereas II was also reduced to (?)-isocarvomenthone (VI), (?)-carvomenthone (VII), (?)-isocarvomenthol (VIII), and (?)-neoisocarvomenthol (IX); of which III, VI and IX are the major products.The metabolic pathways of I and II and mechanism of stereospecific hydrogenation are also discussed. 相似文献
6.
Kosaku Hirota Tetsuo Tomishi Yoshifumi Maki Hironao Sajiki 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):161-173
Abstract Novel synthetic method of 5-arylthiouridine derivatives is described. Treatment of 5-bromo-2′,3′-O-isopropylideneuridine (1a) with diaryl disulfides in the presence of sodium hydride at ambient temperature gave the 5-arylthiouridines (2) in moderate yields. The present method is devised by virtue of a combination of efficient participation of the 5′-hydroxy group onto the uracil ring and the electrophilic nature of diaryl disulfide, which was applied to the synthesis of 5-arylthio-1-β-D-arabinofuranosyl-uracils (8). 相似文献
7.
Hussein I. El Subbagh Li-Jen Ping Elie Abushanab 《Nucleosides, nucleotides & nucleic acids》2013,32(2-4):603-613
Abstract A stereospecific route for the synthesis of pyrimidine 2′-β-D-deoxyribonucleosides has been developed using suitably modified methyl 2-deoxy-D-ribofuranosides. The stereochemistry of the nucleoside bond is dictated by the chirality at C-4 of the pentofuranose. A novel palladium hydroxide catalyzed alcholysis of a nucleoside bond has been discovered. Preliminary studies of the mechanism and limitations of this reaction are described. 相似文献
8.
John A. Walker II Jiong J. Chen Jack M. Hinkley Dean S. Wise Leroy B. Townsend 《Nucleosides, nucleotides & nucleic acids》2013,32(10-11):1999-2012
Abstract The palladium-catalyzed cross-couplings of 2-chloro-3,5-diamino-6-iodopyrazine (1a) and methyl 3-amino-6-iodopyrazine-2-carboxylate (1b) with 1,4-anhydro-3,5-O-bis[(tert-butyl)dimethylsilyl]-2-deoxy-D-erythro-pent-1-enitol (2) followed by desilylation and stereospecific reduction of the 2′-deoxy-3′-keto adduct leads to the formation of 2-chloro-6-(2-deoxy-ß-D-ribofuranosyl)-3,5-diaminopyrazine (4a) and methyl 3-amino-6-(2-deoxy-ß-D-ribofuranosyl)pyrazine-2-carboxylate (4b) in 58% yield and 21% yield, respectively. These are the first syntheses of the heretofore unknown 2′-deoxy pyrazine C-nucleosides and demonstrate the utility of a convergent approach for the synthesis of pyrazine C-nucleosides. 相似文献
9.
H. Jeanette Thomas Robert D. Elliott James M. Riordan John A. Montgomery 《Nucleosides, nucleotides & nucleic acids》2013,32(1):109-121
Abstract Attempts to prepare I -[7,8-anhydro-2,5,6-trideoxy-α-L-lyxo-(and β-n-ribo)-octofuranosyl]thymine (10) by treatment of halohydrins 6–9 with sodium hydride in DMF or sodium methoxide in methanol gave mixtures of the epoxides 10 or 11 and the 3′,8′-anhydronucleoside 12. The structure of 12 was confirmed by oxidation to the cyclic ketone 14. The successful synthesis of 10 involved a Wittig reaction on the thymidine-5′-aldehyde 16 to give the unsaturated ketoacetate 18 which was reduced in two steps to the diacetate 20. The 7′-O-tosyl derivative 21 upon treatment with sodium methoxide in chloroform gave the pure epoxide 10 which was marginally toxic to L1210 cells in culture (I50=25 μM) and demonstrated borderline in vivo activity (24% ILS) against P388 murine leukemia. 相似文献
10.
《Nucleosides, nucleotides & nucleic acids》2013,32(4-5):377-383
ABSTRACT The title compounds were obtained from appropriate 5-substituted uracil derivatives and 1,2-oxy-3-methoxypropane in the presence of sodium hydride. Under similar conditions 5-iodouracil gave 2-methoxymethyl-2,3-dihydro-oxazolo[3,2-c]pyrimidine-5,7-dione as a result of intramolecular cine type nucleophilic substitution. Cytotoxicity of 1-(2-hydroxy-3-methoxypropyl)-5-substituted uracil derivatives against L1210 and macrophage RAW 264.7 cells in vitro was examined. 相似文献
11.
Yu. L. Vechtomova T. A. Telegina M. P. Kolesnikov M. S. Kritsky 《Applied Biochemistry and Microbiology》2010,46(3):339-345
Exposure of deaerated folic acid solutions containing an electron donor to UV radiation (310–390 nm, I = 0.4 W m−2) induced formation of dihydrofolic acid (DHFA), a photoexcitation which gave tetrahydrofolic acid (THFA). Only DHFA was formed in the presence of EDTA (E′o = +0.40 V), while the presence of stronger reductants—NADH (E′o = −0.32 V) and boron hydride (E′o = −0.48 V)—induced photoreduction to THFA. It was demonstrated that UV radiation had no effect on the THFA formylation, giving
the coenzyme 5,10-methenyltetrahydrofolic acid and its transformation into another coenzyme, 5-formyltetrahydrofolic acid. 相似文献
12.
Tun-Cheng Chien David A. Berry John C. Drach Leroy B. Townsend 《Nucleosides, nucleotides & nucleic acids》2013,32(10-12):1971-1996
3-Amino-6-(β-D-ribofuranosyl)imidazo[4,5-c]pyrazole (2) was synthesized via an N-N bond formation strategy by a mononuclear heterocyclic rearrangement (MHR). A series of 5-amino-1-(5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-β-D-ribofuranosyl-4-(1,2,4-oxadiazol-3-yl)imidaz-oles (6a-d), with different substituents at the 5-position of the 1,2,4-oxadiazole, were synthesized from 5-amino-1-(β-D-ribofuranosyl)imidazole-4-carboxamide (AICA Ribose, 3). It was found that 5-amino-1-(5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-β-D-ribofuranosyl)-4-(5-methyl-1,2,4-oxadiazol-3-yl)imidazole (6a) underwent the MHR with sodium hydride in DMF or DMSO to afford the corresponding 3-acetamidoimidazo[4,5-c]pyrazole nucleoside(s) (7b and/or 7a) in good yields. A direct removal of the acetyl group from 3-acetamidoimidazo[4,5-c]pyrazoles under numerous conditions was unsuccessful. Subsequent protecting group manipulations afforded the desired 3-amino-6-(β-D-ribofuranosyl)imidazo[4,5-c]pyrazole (2) as a 5:5 fused analog of adenosine (1). 相似文献
13.
《Journal of enzyme inhibition and medicinal chemistry》2013,28(4):243-258
Abstractβ-Difluoromethyl-β-alanine (3-amino-4,4-difluorobutanoic acid) is a potent in vitro and in vivo inhibitor of GABA-T. The rate of inhibition of GABA-T is concentration- and time-dependent. The inactivation is active-site directed. No reactive species escapes from the active site before reacting with the enzyme. The inhibition is irreversible and stereospecific. The use of β-2H-β-difluoromethyl-β-alanine results in a marked primary isotope effect in vitro and in vivo. The use of differently substituted dihalogeno derivatives of β-alanine suggests that the rate of inhibition is dependent on the nature and position of the leaving group. The mechanism of inhibition is discussed on the basis of spectral changes. 相似文献
14.
Abstract The 3′-β-C-branched anhydrohexitol nucleosides have been conveniently synthesised starting from commercially available D-ribose following the reaction sequence: (i) conversion of protected pentofuranose sugar to the corresponding hexopyranosyl nitrosugar (ii) addition of the conjugate base of nitrosugar to formaldehyde to obtain C-branched nitro sugar (iii) removal of nitro group by n-tributyltin hydride treatment and (iv) Mitsunobu type alkylation to build up the nucleobase. 相似文献
15.
《Nucleosides, nucleotides & nucleic acids》2013,32(5-8):1459-1461
Abstract An efficient and stereospecific synthesis of dinucleoside 4′-(2,2′:6′,2″-terpyridyl)phosphonate 2 and 5-(2,2′-bipyridyl)phosphonate 3 via a palladium(0) cross coupling strategy has been developed. 相似文献
16.
17.
Herbert C. Lee Piyush Kumar Leonard I. Wiebe Robert McDonald John R. Mercer Kazue Ohkura 《Nucleosides, nucleotides & nucleic acids》2013,32(9):1995-2016
Abstract The stereospecific synthesis of 1-(5-deoxy-5-iodo-α-D-arabino-furanosyl)-2-aminoimidazole (iodoaminoimidazole arabinoside: IAIA, 2) is described. The reaction of the protected sugar bromide (8) and trifluoroacetamidoimidazole (10B) gave the coupled product (11B), which gave the free nucleoside (4) on deblocking. It was identical with AIA obtained by reduction of AZA (azomycin arabinoside), whose anomeric configuration was found to be a by the X-ray crystallography. 相似文献
18.
Galal H. Elgemeie Mamdouh A. Abu-Zaied Abdel-Tawab H. Mossa 《Nucleosides, nucleotides & nucleic acids》2019,38(3):183-202
This study reports a novel and efficient method for the synthesis of the first reported novel class of pyrazole thioglycosides 6a–h. These series of compounds were designed through the reaction of sodium 2-cyano-3-oxo-3-(4-substitutedphenylamino)prop-1-ene-1,1-bis(thiolate) salts 2 with hydrazine hydrate in ethanol at room temperature to give the corresponding sodium 5-amino-4-(substitutedphenylcarbamoyl)-1H-pyrazole-3-thiolates 3a–d. The latter compounds were treated with protected α-D-gluco- and galacto-pyranosyl bromides 4a,b in DMF at ambient temperature to give in a high yields the corresponding pyrazole thioglycosides 6a–h. Treatment of pyrazole salts 3a–d with hydrochloric acid at amobient temperature afforded the corresponding 3-mercaptopyrazole derivatives 5. The latter compounds were treated with peracetylated sugars 4 in sodium hydride in ethanol at ambient temperature to tolerate the S-glycosyl 6a–h compounds. Ammonolysis of the pyrazole thioglycosides 6a–h afforded the corresponding free thioglycosides 7a–h. The toxicity and antitumor activities of the synthesized compounds were studied. 相似文献
19.
20.
Lech A. Ciszewski Pawel Lipka Wu-Yon Ren Kyoichi A. Watanabe 《Nucleosides, nucleotides & nucleic acids》2013,32(5):487-498
Abstract As an epimerization resistant synthon in the synthesis of oligo-nucleotides consisting of C-nucleoside analogues, hitherto unknown 5-benzyloxy-methyl-3-(2-deoxy-β-D-erythro-pentofuranosyl)pyrrolo[3,2-d]pyrimpyrimidine (7-benzyloxymethyl-2′-deoxy-9-deazaadenosine) was prepared in seven steps from the known 3-amino-2-cyano-4-(2,3-O-isopropylidene-5-O-trityl-β-D-ribofuranosyl)-pyrrolpyrrole (1). Treatment of 1 with benzyl chloromethyl ether in the presence of potassium t-butoxide and 18-crown-6 afforded the N-protected pyrrole 2, which was converted into the 9-deazapurine derivative 3 in high yield by heating in EtOH. 7-Benzyloxymethyl-9-deazaadenosine 4 was obtained from 3 by acid hydrolysis in 2.5% methanolic hydrogen chloride. After protection of the hydroxyl groups of 4 with Markievicz's reagent, the product 5 was converted into the 2′-O-phenoxythiocarbonyl derivative 6. Reduction of 6 with butyltin hydride in the presence of 2,2′-azobis(2-methylpropionitrile), followed by desilylation with triethylammonium fluoride, afforded the desired 7-benzyloxymethyl-2′-deoxy-9-deazaadenosine (8) in high overall yield. The benzyloxymethyl group of 8 was removed by hydrogenolysis over palladium hydroxide (Degussa type) to give 2′-deoxy-9-deazaadenosine (9) in quantitative yield. The structure of 9 is discussed. 相似文献