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Entecavir can significantly inhibit the replication of HBV-DNA, reduce the HBV-DNA level in blood se- rum. But suffering from low oral bioavailability, entecavir has low intestinal membrane permeability and poor meta- bolic stability. In this study, 12 different derivatives of entecavir 4'-ester were regioselectively synthesized and their apical-to-basolateral permeabilities across Caco-2 cells and HBV-DNA inhibitory efficacies were evaluated. Most of the compounds showed high permeabilities across Caco-2 cells compared with entecavir, compounds 5b and 5e also exhibited comparable anti-HBV activities with that of entecavir, especially. 相似文献
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Xi GONG Xiao Xiao YANG De Xin WANG 《中国化学快报》2006,17(4):469-472
Eight N-substituted diketopiperazines (DKPs) were synthesized by solid-phase protocols. The introduction of iminodiacetic acid (Ida) and followed another α-amino acid residue as the precursor of DKP framework made the present synthesis to be very facile and efficient. 相似文献
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Xiaoyu LiuXiaozhen Jiao Qian WuChengsen Tian Renze LiPing Xie 《Tetrahedron letters》2012,53(29):3805-3807
A practical synthesis of Entecavir (1) has been accomplished in 10 steps with 21% overall yield. The key steps to construct the five-membered carbocyclic framework 2 are a ring-closing metathesis and a diethyl-aluminum 2,2,6,6-tetramethyl piperidide (DA-TMS) mediated epoxide isomerization. Furthermore, the guanine was introduced by modified Mitsunobu reaction. 相似文献
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影响有机合成选择性和收率的因素主要包括反应机理、反应温度、立体效应、副反应等。由于缺乏相关数据和方法,一般很难对反应的影响因素(如溶剂和反应温度)进行理论预测,这使得合成路线的优化非常繁琐耗时。本论文基于反应的可能机理,在估算活化能的基础上,利用物理化学原理对温度的影响进行了讨论。结果表明,运用物理化学原理进行简单分析即可对有机合成路线的优化提供有益的理论指导。 相似文献
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DaLiYIN JiYuGUO XiaoTianLIANG 《中国化学快报》2003,14(7):670-672
AF-5 was synthesized through a convergent method. The key step was the Robinson annulation using a key intermediate pentyl vinyl ketone. 相似文献
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Cai Hong XU Ning ZHOU Ze Min XIE Center for Molecular Science Institute of Chemistry the Chinese Academy of Sciences Beijing 《中国化学快报》2000,11(9)
Since the pioneering work of Verbeek', considerable attention has focussed on researchdevoted to the preparation of silicon nitride- and silicon carbide- based ceramic materials.Owing to their promising potential for the formation of high-purity non-oxide siliconbased ceramics, organosilicon compounds (precursors) have attracted considerableinterest in recent years 2. The structures and the chemical composition of the precursorsstrongly effect the properties of the final ceramic materials. Acc… 相似文献
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本文报道根据Corey和Seebach“羰基反应活性逆转”原理合成二茂铁基α-二酮的新途径。用锂化二茂铁基二噻烷与一个酯反应,再经HgCl_2-CdCO_3水解得到标题化合物。共合成16种酰基二茂铁基二噻烷和13种二茂铁基α-二酮化合物。除两种外,其余均为新二茂铁衍生物。所有产物的结构都由元素分析、IR和~1H NMR谱确定。本文讨论了反应中二茂铁衍生物在结构及性质上的特点和产物的IR和~1H NMR谱。 相似文献
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Mohamed Abdel‐Megid 《合成通讯》2013,43(18):3211-3218
Condensation of 4‐acetyl‐5,6‐diphenyl‐2,3‐dihydropyridzin‐3‐one (1) with dimethylformamide dimethylacctal (DMFDMA) afforded the enaminone 2. This could be converted into the pyrazolylpyridazine derivative 4 on reaction with hydrazine hydrate and into pyridazinylpyridazinone 7a,b via coupling with aromatic diazonium salts and subsequent treatment with active methylene compounds. The reaction of 6 with dimethyl acetylenedicarboxylate in the presence of triphenylphosphine afforded the pyridazinylpyridazine derivative 8. Compound 1 converted into 9 upon reflux in acetic acid in the presence of ammonium acetate and afforded 10 on reflux in acetic acid. 相似文献
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二茂铁甲醛是有机合成化学中一个重要的中间体,利用它可以合成各种功能二茂铁衍生物.然而异环取代的二茂铁甲醛因合成难度较大使其应用受到限制,1'-碘代二茂铁甲醛分子内因为有较多的反应活性点,从而被广泛应用到功能金属有机分子的设计合成中.合成该物质的传统方法不仅路线长,且需要使用昂贵的金属有机试剂.我们利用改进后的合成方法,以二茂铁为起始原料经三步反应合成了1'-碘代二茂铁甲醛.该方法不仅缩短了合成路线,简化了反应条件,且避免使用苛刻的反应条件和贵重的有机锂(锡)试剂,是目前合成该化合物最简单的方法. 相似文献
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The axially chiral monophosphine 2-(diphenylphosphino)-2′-methoxy-1,1′-binaphthyl (MeO-MOP) is a versatile ligand. We report a shorter (four steps from chiral BINOL), more atom-economical synthetic route to MeO-MOP. (R)-BINOL is transformed into its monomethyl ether by the Mitsunobu reaction, and the latter is reacted with triflic anhydride to give its triflate. The C-P coupling of the triflate and diphenylphosphine oxide catalyzed by palladium give a phosphine oxide, the precursor of (R)-MeO-MOP, which is reduced with trichlorosilane to furnish (R)-MeO-MOP. 相似文献
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Doan Pham Minh Jocelyn Ramaroson Ange Nzihou Patrick Sharrock Guy Depelsenaire 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):112-120
Abstract Thermal synthesis of sodium cyclotriphosphate (SCTP) – Na3P3O9 was investigated in the temperature range of 150 °C to 750 °C using sodium chloride (NaCl) and 85 wt% orthophosphoric acid (H3PO4) as economical starting materials. Reaction temperature had a crucial impact on the chloride elimination rate and the formation of SCTP. The best result was obtained at 600 °C with 96% of elimination of the initial chloride as hydrochloric acid and 84% of selectivity in SCTP. At lower temperatures, residual chloride contents were high. At higher temperatures (650 °C and 750 °C), SCTP was melted and transformed into glassy products. 相似文献
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CO2化学利用的一条新途径 总被引:3,自引:0,他引:3
C02开发利用一直是世界各国大型化工企业异常关注的研究课题,但是,由于C02结构稳定,化学活性差,因而决定了该领域的研究课题难度较大,进展比较缓慢.本文报道了一种利用天然气还原C02制备会成气的最新研究结果,该过程不仅可以为破一化学工业提供廉价原料,从而开辟一条极重要的非石油原料的化学工业路线,而且对减缓全球性温室效应也具有一定的社会意义.1实验日分1·1催化剂制备按表1所列组成,以7-AI。0。、硝酸镍、硝酸镁和稀土硝酸盐为原料,采用常规浸渍法参照文献[‘]制备催化剂.1·Zfffe反应评价催化反应评价采用双套管… 相似文献
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A multi-step reaction route was developed to synthesize boron nitride(BN) nanoparticles via the reaction between NaN3 and BCl3 in a benzene-thermal solution. By means of this route, the crystallinity of BN nanoparticles was improved via increasing the reaction steps. Meanwhile, a phase transformation from hexagonal BN(hBN) or turbostratic BN(tBN) to cubic BN(cBN) occurred, resulting in the increase of cBN content. Moreover, the content of cBN also slightly increased when the temperature was elevated from 265 ℃ to 280 ℃. 相似文献
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A new low‐temperature synthesis route of the strongly red‐emitting Eu2+ activated nitride phosphor CaAlSiN3 is presented. The fluorides CaSiF6 and AlF3 were used as a source of metal ions and Li3N as a nitrogen source. A KCN/LiCl flux system was employed to lower the temperature of the reaction from 1100 to 750 °C. The course of the reaction was studied by differential thermal analysis, and the product of the reaction was inspected by X‐ray powder diffraction and luminescence measurements of CaAlSiN3:Eu. 相似文献
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The authors developed a simple solvothermal route to synthesis of PbS nanocrystals in the mild binary mixed solvent made of diethylenetriamine (DETA) and water. Two kinds of PbS nanostructures (dice‐like and cubic) have been successfully synthesized in the binary mixed solvothermal system at 150 °C by changing the sulfur source. The products were characterized by X‐ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The results show that the as‐prepared dice‐like PbS crystals have a hole on each of their faces. To elucidate the relationship between reaction systems and the morphologies of the final products, the authors also investigated the crystal growth by using different sulfur source. Based on the experimental results, the possible growth mechanism of the dice‐like PbS crystals was proposed. 相似文献