共查询到20条相似文献,搜索用时 968 毫秒
1.
Yoshihiro Hayakawa Reiko NagataAkiyoshi Hirata Mamoru HyodoRie Kawai 《Tetrahedron》2003,59(34):6465-6471
This paper describes a new method for synthesizing biologically important cyclic bis(3′→5′)diguanylic acid (cGpGp) in a higher yield than that of the existing synthetic method. In the new synthesis, the following two means, in place of those used in the existing synthesis are employed as main strategies to cause the increase in product yield. One of these distinctive strategies in the new synthesis is that the phosphoramidite method is used for the preparation of a key synthetic intermediate of a linear guanylyl(3′→5′)guanylic acid derivative. This method allowed higher-yield formation of the intermediate than that by the triester method used in the existing synthesis. The second distinctive strategy used in the new synthesis is that allyloxycarbonyl and allyl groups are used for the protection of two guanine bases and two internucleotide bonds, respectively. These four allylic protectors can be removed all at once by the organopalladium-catalyzed reaction under neutral conditions. Thus, deprotection of the protected cGpGp precursor was achieved in the present synthesis in a shorter step and under milder conditions than the deprotection achieved in the existing synthesis, which uses diphenylacetyl and o-chlorophenyl groups as protectors for two guanine bases and two internucleotide bonds, respectively, whose full removal requires two different procedures including rather harsh basic treatment. As a result, technical loss and decomposition of the target product in the new synthesis is remarkably reduced. 相似文献
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A new method has been found for the synthesis of pyrazoleacetate esters from pyrazolaldehyde. By a new tandem reaction, in which methyl 4‐pyrazoleacetate was reacted with carbon disulfide and iodomethane, thieno[2,3‐c]pyrazole was synthesized. This was an easy method for the synthesis of this type of heterocycle. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 303–305, 1999 相似文献
4.
Gürol Okay 《合成通讯》2013,43(11-12):2125-2132
The new method for the stereoselective synthesis of disubstituted diene ester was successfully applied to a highly stereoselective synthesis of E, Z-diene ester (1). 相似文献
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<正>A convenient method for the synthesis of ezetimibe analogs as cholesterol absorption inhibitors was described.The key step in the synthesis was the intramolecular ring formation through Mitsunobu reaction.Furthermore,a new series of analogs was designed and synthesized. 相似文献
6.
David L. Snitman Richard J. Himmelsbach R.Curtis Haltiwanger David S. Watt 《Tetrahedron letters》1979,20(27):2477-2480
A new method for the synthesis of highly substituted catechols involving the decarboxylation of an α,β-epoxyenone was developed and employed in a synthesis of two diterpenes, cryptojaponol and taxodione. 相似文献
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A new oxidation method for DNA synthesis was developed by the use of 1,1-dihydroperoxycyclododecane in CH2Cl2-EtOAc under anhydrous conditions. This new oxidizer was successfully applied to the synthesis of oligodeoxyribonucleotides that involves an oxidation step for conversion of phosphite intermediates to phosphate derivatives. 相似文献
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Three new routes were established for the synthesis of biologically active murrayaquinone A and a new method was developed for synthesis of murrayanine from the same starting material as 4-hydroxy carbazole. During the synthetic course a few novel observation were recorded, which include two one pot reaction sequences and C–N bond cleavage by sodium cyanoborohydride. 相似文献
9.
G.B. Dharma RaoM.P. Kaushik 《Tetrahedron letters》2011,52(39):5104-5106
A simple and efficient trans-acetoacylation method for the synthesis of β-keto ester derivatives has been described using ytterbium(III) triflate as a new catalyst under solvent-free condition. This method was found to be efficient and convenient for the synthesis of a wide variety of β-keto ester derivatives. 相似文献
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A new and efficient method was developed for the synthesis of novel gem-difluoromethylene-containing isocyanide, which can be used as a building block for the synthesis of difluorinated pseudopeptides via Ugi reaction. 相似文献
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Bergeron-Brlek M Giguère D Shiao TC Saucier C Roy R 《The Journal of organic chemistry》2012,77(6):2971-2977
A catalytic synthesis of novel biaryl-linked divalent glycosides was achieved using an electroreductive palladium-catalyzed iodoaryl-iodoaryl coupling reaction. This new method was optimized for the synthesis of divalent biaryl-linked mannopyranosides that was subsequently generalized toward several carbohydrate substrates with yields up to 96%. 相似文献
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Viacheslav Lysenko Dr. Kostiantyn Shvydenko Prof. Kostiantyn Nazarenko Dr. Svitlana Shishkina Eduard Rusanov Prof. Aleksandr Kostyuk 《European journal of organic chemistry》2023,26(17):e202300142
A convenient method for the synthesis of 10- and 11-membered azalactams via reductive cleavage of bicyclic systems featuring an amidine fragment was studied. It was found that the ring-expansion reaction of bicyclic dihydropyrimidones depends on the ring size of saturated fragment, substituents in the pyrimidone core and reaction conditions. A new efficient method for the synthesis of medium ring azalactams by reductive cleavage of quaternary salts of annulated dihydropyrimidones was proposed as well. The obtained medium ring azalactams with a secondary amine function were used in the synthesis of bicyclic heteroaromatic systems. 相似文献
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A new and convenient one-pot method for the preparation of unsymmetrical selenides has been developed. In the presence of cesium hydroxide, molecular sieves, and DMF, benzeneselenol undergoes direct alkylation with various alkyl halides for the synthesis of alkyl phenyl selenides in moderate to excellent yields. Another method to prepare unsymmetrical organoselenides was also completed by coupling terminal alkynes with benzeneselenyl bromide. As an application, the synthesis of a selenopeptide was also accomplished. Furthermore, this methodology was extended to the synthesis of an organoselenide on solid support. 相似文献
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Salo PK Pertovaara AM Salo VM Salomies HE Kostiainen RK 《Journal of combinatorial chemistry》2003,5(3):223-232
A high-performance thin-layer chromatography (HPTLC) method was developed for fast evaluation of the purity of solid-phase synthesis products. The results obtained were in good agreement with results obtained by the LC-MS method (r(2) = 0.8404) or by the LC-UV method (r(2) = 0.8053), confirming the suitability of HPTLC for purity analysis of combinatorial syntheses. The synthesis products can be quantified and identified by measuring UV densitograms or in situ UV spectra or by ESI-MS after isolation of the zone of interest. A new, simple, and fast method for transferring the zone of the analyte from the plate to the ESI-MS equipment is described. The new HPTLC method enables rapid and efficient analysis of approximately 40 samples in parallel. As such, it offers a cheaper and easier way to analyze the purity of synthesis products than the commonly used LC-UV-MS. 相似文献
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A new method for the synthesis of 3-N-phthaloyl homophenylalanine lactone has been developed and its mechanism was proposed. 相似文献
17.
L. Giribabu Ch. Vijay Kumar A. Surendar V. Gopal Reddy M. Chandrasekharam P. Yella Reddy 《合成通讯》2013,43(23):4141-4147
A novel, highly efficient, single‐step synthesis of subphthalocyanines using microwave irradiation of phthalonitrile and boron trichloride in 1‐chloronaphthalene was accomplished for the first time. This provides a new preparative method for the synthesis of subphthalocyanines with reduced reaction times and improved yields. 相似文献
18.
A New and Efficient Synthesis of Wedelolactone Derivatives 总被引:1,自引:0,他引:1
A new and facile method based on an intermolecular cycloaddition was described for the synthesis of wedelolactone derivatives. 相似文献
19.
Dr. Yoko Yasuno Iho Mizutani Yuki Sueuchi Yuuka Wakabayashi Nozomi Yasuo Dr. Keiko Shimamoto Prof. Dr. Tetsuro Shinada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5145-5148
Catalytic asymmetric hydrogenation of dehydroamino acid esters with biscarbamate protection was examined for the first time to prepare optically active amino acids. The new method was successfully applied to the synthesis of new cystine–glutamate exchanger inhibitors. 相似文献
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An advanced, known intermediate for discodermolide synthesis was prepared by an efficient sequence from the readily available fermentation product oleandomycin. The scheme makes use of a new method for the direct cleavage of aminoglycosides, a critical double-bond isomerization, and a selective protection of two of three hydroxyl groups in a modified oleandolide. This synthesis illustrates a new strategy, "deconstruction-reconstruction", for accessing stereochemically complex polyketide building blocks. 相似文献