共查询到20条相似文献,搜索用时 15 毫秒
1.
Daniela Ubiali Carla D. Serra Immacolata Serra Carlo F. Morelli Marco Terreni Alessandra M. Albertini Paolo Manitto Giovanna Speranza 《Advanced Synthesis \u0026amp; Catalysis》2012,354(1):96-104
Purine nucleoside phosphorylase (PNP) from Aeromonas hydrophila encoded by the deoD gene has been over‐expressed in Escherichia coli, purified, characterized about its substrate specificity and used for the preparative synthesis of some 6‐substituted purine‐9‐ribosides. Substrate specificity towards natural nucleosides showed that this PNP catalyzes the phosphorolysis of both 6‐oxo‐ and 6‐aminopurine (deoxy)ribonucleosides. A library of nucleoside analogues was synthesized and then submitted to enzymatic phosphorolysis as well. This assay revealed that 1‐, 2‐, 6‐ and 7‐modified nucleosides are accepted as substrates, whereas 8‐substituted nucleosides are not. A few transglycosylation reactions were carried out using 7‐methylguanosine iodide ( 4 ) as a D ‐ribose donor and 6‐substituted purines as acceptor. In particular, following this approach, 2‐amino‐6‐chloropurine‐9‐riboside ( 2c ), 6‐methoxypurine‐9‐riboside ( 2d ) and 2‐amino‐6‐(methylthio)purine‐9‐riboside ( 2g ) were synthesized in very high yield and purity. 相似文献
2.
Xinrui Zhou Kathleen Szeker Lin‐Yu Jiao Martin Oestreich Igor A. Mikhailopulo Peter Neubauer 《Advanced Synthesis \u0026amp; Catalysis》2015,357(6):1237-1244
The enzymatic transglycosylation of 2,6‐dichloropurine (26DCP) and 6‐chloro‐2‐fluoropurine (6C2FP) with uridine, thymidine and 1‐(β‐D ‐arabinofuranosyl)‐uracil as the pentofuranose donors and recombinant thermostable nucleoside phosphorylases from G. thermoglucosidasius or T. thermophilus as biocatalysts was studied. Selection of 26DCP and 6C2FP as substrates is determined by their higher solubility in aqueous buffer solutions compared to most natural and modified purines and, furthermore, synthesized nucleosides are valuable precursors for the preparation of a large number of biologically important nucleosides. The substrate activity of 26DCP and 6C2FP in the synthesis of their ribo‐ and 2′‐deoxyribo‐nucleosides was closely similar to that of related 2‐amino‐ (DAP), 2‐chloro‐ and 2‐fluoroadenines; the efficiency of the synthesis of β‐D ‐arabinofuranosides of 26DCP and 6C2FP was lower vs. that of DAP under similar reaction conditions. For a convenient and easier recovery of the biocatalysts, the thermostable enzymes were immobilized on MagReSyn® epoxide beads and the biocatalyst showed high catalytic efficiency in a number of reactions. As an example, 6‐chloro‐2‐fluoro‐(β‐D ‐ribofuranosyl)‐purine ( 9 ), a precursor of various antiviral and antitumour drugs, was synthesized by the immobilized enzymes at 60 °C under high substrate concentrations (uridine:purine ratio of 2:1, mol). The synthesis was successfully scaled‐up [uridine (2.5 mmol), base (1.25 mmol); reaction mixture 50 mL] to afford 9 in 60% yield. The reaction reveals the great practical potential of this enzymatic method for the efficient production of modified purine nucleosides of pharmaceutical interest.
3.
Daniela Ubiali Silvia Rocchietti Francesca Scaramozzino Marco Terreni AlessandraM. Albertini Roberto Fernndez‐Lafuente JosManuel Guisn Massimo Pregnolato 《Advanced Synthesis \u0026amp; Catalysis》2004,346(11):1361-1366
Multimeric uridine phosphorylase (UP) and purine nucleoside phosphorylase (PNP) of Bacillus subtilis have been expressed from genes cloned in Escherichia coli, purified, characterized, immobilized and stabilized on solid support. A new immobilization strategy has been developed for UP onto Sepabeads coated with polyethyleneamine followed by cross‐linking with aldehyde‐dextran. PNP has been immobilized onto glyoxyl‐agarose. At pH 10 and 45 °C these derivatives catalyzed the transglycosylation of 2′‐deoxyuridine to 2′‐deoxyguanosine in high yield (92%). Under the same conditions the not immobilized enzymes were promptly inactivated. 相似文献
4.
Hai‐Ming Guo Chao Xia Hong‐Ying Niu Xiao‐Ting Zhang Si‐Nan Kong Dong‐Chao Wang Gui‐Rong Qu 《Advanced Synthesis \u0026amp; Catalysis》2011,353(1):53-56
A highly selective method for the synthesis of N‐9 alkylated purine nucleoside derivatives via an intermolecular hydrogen abstraction reaction between nitrogen radicals in purine rings and alkyl ethers was developed. Novel purine nucleoside derivatives were obtained with good to high yields in the presence of (diacetoxyiodo)benzene (DIB) and iodine in one‐step reaction. 相似文献
5.
Mikhail S. Drenichev Vladimir E. Oslovsky Anastasia A. Zenchenko Claudia V. Danilova Mikhail A. Varga Roman S. Esipov Dmitry D. Lykoshin Cyril S. Alexeev 《International journal of molecular sciences》2022,23(5)
A comparative analysis of the transglycosylation conditions catalyzed by E. coli nucleoside phosphorylases, leading to the formation of 2′-deoxynucleosides, was performed. We demonstrated that maximal yields of 2′-deoxynucleosides, especially modified, can be achieved under small excess of glycosyl-donor (7-methyl-2′-deoxyguanosine, thymidine) and a 4-fold lack of phosphate. A phosphate concentration less than equimolar one allows using only a slight excess of the carbohydrate residue donor nucleoside to increase the reaction’s output. A three-step methodology was elaborated for the preparative synthesis of purine-modified 2′-deoxyribonucleosides, starting from the corresponding ribonucleosides. 相似文献
6.
Dr. Montserrat Terrazas Adele Alagia Ignacio Faustino Prof. Dr. Modesto Orozco Prof. Dr. Ramon Eritja 《Chembiochem : a European journal of chemical biology》2013,14(4):510-520
The development of nucleic acid derivatives to generate novel medical treatments has become increasingly popular, but the high vulnerability of oligonucleotides to nucleases limits their practical use. We explored the possibility of increasing the stability against 3′‐exonucleases by replacing the two 3′‐terminal nucleotides by N‐ethyl‐N‐coupled nucleosides. Molecular dynamics simulations of 3′‐N‐ethyl‐N‐modified DNA:Klenow fragment complexes suggested that this kind of alteration has negative effects on the correct positioning of the adjacent scissile phosphodiester bond at the active site of the enzyme, and accordingly was expected to protect the oligonucleotide from degradation. We verified that these modifications conferred complete resistance to 3′‐exonucleases. Furthermore, cellular RNAi experiments with 3′‐N‐ethyl‐N‐modified siRNAs showed that these modifications were compatible with the RNAi machinery. Overall, our experimental and theoretical studies strongly suggest that these modified oligonucleotides could be valuable for therapeutic applications. 相似文献
7.
Hayato Sakai Ken Tsutsumi Tsumoru Morimoto Kiyomi Kakiuchi 《Advanced Synthesis \u0026amp; Catalysis》2008,350(16):2498-2502
One‐pot, four‐step syntheses of indoles using both solid‐supported heterogeneous and homogeneous palladium catalysts and reagents were carried out. Such a combination of these two‐phase catalysts and reagents causes a dramatic increase in yield, and it is a simple process. The presented methodology is effective for four‐step reactions to provide various functionalized indoles. 相似文献
8.
Characterization of a Galactosynthase Derived from Bacillus circulans β‐Galactosidase: Facile Synthesis of D‐Lacto‐ and D‐Galacto‐N‐bioside 下载免费PDF全文
Dr. Chao Li Prof. Dr. Young‐Wan Kim 《Chembiochem : a European journal of chemical biology》2014,15(4):522-526
Glycosynthases—retaining glycosidases mutated at their catalytic nucleophile—catalyze the formation of glycosidic bonds from glycosyl fluorides as donor sugars and various glycosides as acceptor sugars. Here the first glycosynthase derived from a family 35 β‐galactosidase is described. The Glu→Gly mutant of BgaC from Bacillus circulans (BgaC‐E233G) catalyzed regioselective galactosylation at the 3‐position of the sugar acceptors with α‐galactosyl fluoride as the donor. Transfer to 4‐nitophenyl α‐D ‐N‐acetyl‐glucosaminide and α‐D ‐N‐acetylgalactosaminide yielded 4‐nitophenyl α‐lacto‐N‐biose and α‐galacto‐N‐biose, respectively, in high yields (up to 98 %). Kinetic analysis revealed that the high affinity of the acceptors contributed mostly to the BgaC‐E233G‐catalyzed transglycosylation. BgaC‐E233G showed no activity with β‐(1,3)‐linked disaccharides as acceptors, thus suggesting that this enzyme can be used in “one‐pot synthesis” of LNB‐ or GNB‐containing glycans. 相似文献
9.
Xuesong Wang Xingyong Wang Dayun Huang Chulong Liu Xinyan Wang Yuefei Hu 《Advanced Synthesis \u0026amp; Catalysis》2016,358(14):2332-2339
A novel method for the synthesis of 3‐iodoquinolines was developed by copper‐catalyzed tandem annulation from diaryliodoniums, nitriles, and 1‐iodoalkynes. It is a method that is characterized by the most convenient operation and wide molecular diversity.
10.
Ke‐Feng Zhang Jing Nie Ran Guo Yan Zheng Jun‐An Ma 《Advanced Synthesis \u0026amp; Catalysis》2013,355(17):3497-3502
An enantioselective aza‐Friedel–Crafts (F‐C) reaction of indoles with cyclic N‐acylketimines has been developed. By using chiral phosphoric acid catalysts, a wide range of enantioenriched trifluoromethyldihydroquinazolines was obtained in excellent yields (up to 98%) with good to high enantioselectivities (up to 99% ee).
11.
Ke‐Feng Zhang Jing Nie Ran Guo Yan Zheng Jun‐An Ma 《Advanced Synthesis \u0026amp; Catalysis》2014,356(10):2133-2133
12.
Chenyi Yi Ruimao Hua Hanxiang Zeng Qiufeng Huang 《Advanced Synthesis \u0026amp; Catalysis》2007,349(10):1738-1742
An efficient and practical synthetic method has been developed for the preparation of symmetrical diarylacetylenes from the direct reaction of aryl chlorides with 2‐methyl‐3‐butyn‐2‐ol catalyzed by palladium(II) chloride‐bis(tricyclohexylphosphine) [PdCl2(PCy3)2] under mild reaction conditions. Unsymmetrical diarylated acetylenes could be also obtained by using two different aryl chlorides simultaneously. The catalytic procedure includes a novel one‐pot palladium‐catalyzed, double Sonogashira coupling of inactivated aryl chlorides without use of copper(I) as co‐catalyst. 相似文献
13.
Sungjin Kim Daehwan Kim Jaiwook Park 《Advanced Synthesis \u0026amp; Catalysis》2009,351(16):2573-2578
The aerobic oxidation of various hydroquinones was achieved by using copper nanoparticles entrapped in aluminum oxyhydroxide [Cu/AlO(OH)] at room temperature. Furthermore, 2,5‐diamino‐1,4‐benzoquinones were synthesized directly from hydroquinone and amines by a one‐pot procedure consisting of the copper‐catalyzed aerobic oxidation of hydroquinones and the double addition of amines to the resulting quinones. 相似文献
14.
15.
Various arylhydrazones have been successfully synthesized via a highly efficient palladium‐catalyzed cross‐coupling reaction between aryl halides and benzophenone hydrazone. All the reaction parameters have been studied and coupling products were obtained with excellent yields from the corresponding bromides or chlorides. 相似文献
16.
Synthesis of CLA‐Rich Lysophosphatidylcholine by Immobilized MAS1‐H108A‐Catalyzed Esterification: Effects of the Parameters and Monitoring of the Reaction Process 下载免费PDF全文
Daoming Li Weifei Wang Li Zhang Nan Liu Muniba Faiza Chin Ping Tan Bo Yang Dongming Lan Yonghua Wang 《European Journal of Lipid Science and Technology》2018,120(6)
17.
Ales Machara Lukas Werner Mary Ann Endoma‐Arias D. Phillip Cox Tomas Hudlicky 《Advanced Synthesis \u0026amp; Catalysis》2012,354(4):613-626
An improved preparation of buprenorphine via palladium‐catalyzed N‐demethylation/acylation is reported. Three routes were investigated and compared in overall yield. The first involved N‐demethylation/acylation of an advanced intermediate obtained from thebaine followed by hydrolysis of the N‐acetamide and alkylation with cyclopropylmethyl bromide and/or reduction of the N‐acetyl group with the Schwartz reagent followed by N‐alkylation. The second route employed cyclopropylcarboxylic acid anhydride in the N‐demethylation/acylation protocol and subsequent reduction of the cyclopropylcarboxamide by either lithium aluminum hydride or under hydrosilylation conditions. Both of these routes originated in thebaine and therefore required O‐demethylation as a final step. The third route employed an N‐demethylation/acylation sequence starting from oripavine rather than thebaine, thus avoiding the O‐demethylation. The routes are compared for overall efficiency and experimental and spectral data are provided for all new compounds. 相似文献
18.
M. Lakshmi Kantam Rajashree Chakravarti Venkat Reddy Chintareddy B. Sreedhar Suresh Bhargava 《Advanced Synthesis \u0026amp; Catalysis》2008,350(16):2544-2550
An efficient method for the synthesis of industrially important dibenzyls and alkyl phenyl esters via sequential Heck coupling and hydrogenation of the alkenyl double bond in one pot with a single recyclable catalyst under mild conditions has been realised. The catalyst was recovered by simple filteration and reused for several cycles with consistent activity. 相似文献
19.
Subhasish Biswas Maloy Nayak Sanjeev Kanojiya Sanjay Batra 《Advanced Synthesis \u0026amp; Catalysis》2011,353(18):3330-3334
The copper‐catalyzed cascade reaction comprising the condensation/α‐arylation between 2‐halobenzaldehydes and α‐amino acid esters provides a straightforward methodology for the efficient synthesis of alkyl 2H‐isoindole‐1‐carboxylates. 相似文献
20.
Zheng‐Jun Quan Wang‐Hua Hu Zhang Zhang Yu‐Xia Da Xiao‐Dong Jia Xi‐Cun Wang 《Advanced Synthesis \u0026amp; Catalysis》2013,355(5):891-900
The molecular iodine‐catalyzed three‐component reaction of amides or amide derivatives, paraformaldehyde and styrenes allows for the clean generation of allylamine derivatives in good yields and high regioselectivities. The reaction, forming water as the sole co‐product, is an experimentally easy to conduct transformation in the absence of transition metals under mild conditions. 相似文献