氨基噁唑啉呫吨类BACE1抑制剂的特征结构与作用机制

β-分泌酶(BACE1)是治疗阿尔兹海默症(AD)的潜在靶点,BACE1抑制剂的开发已成为治疗AD的重要方向。本文运用比较分子相似性指数(CoMSIA)和分子对接法对66个氨基噁唑啉呫吨类BACE1抑制剂进行模拟分析,建立了可靠的构效关系预测模型(Q~2=0.86,R_(ncv)~2=0.97,R_(pre)~2=0.88),揭示了影响分子抑制活性的重要特征结构信息,发现抑制剂通过与BACE1之间形成的氢键作用和π-π堆积作用占据了分泌酶的S3、S1和S2'三个活性位点。实验所得模型和信息为后续新型高效BACE1抑制剂的结构优化和改造提供了重要的理论指导。     

氨基恶唑啉呫吨类BACE1抑制剂的特征结构与作用机制

β-分泌酶(BACE1)是治疗阿尔兹海默症(AD)的潜在靶点,BACE1抑制剂的开发已成为治疗AD的重要方向。本文运用比较分子相似性指数(CoMSIA)和分子对接法对66个氨基恶唑啉呫吨类BACE1抑制剂进行模拟分析,建立了可靠的构效关系预测模型(Q₂=0.86, R_ncv2=0.97, R_pre2=0.88),揭示了影响分子抑制活性的重要特征结构信息,发现抑制剂通过与BACE1之间形成的氢键作用和π-π堆积作用占据了分泌酶的S3、S1和S2"三个活性位点。实验所得模型和信息为后续新型高效BACE1抑制剂的结构优化和改造提供了重要的理论指导。     

雌激素β受体喹啉类配体的分子对接及3D-QSAR研究

对33个喹啉衍生物的雌激素β受体活性进行了分子对接以及比较分子力场分析(CoMFA)和比较分子相似性指数分析(CoMSIA). 对接结果显示氢键和疏水作用是配体与受体结合的主要因素,同时结果亦显示对接结合能与观测值pIC50具有极显著的线性相关性. 根据对接后各优势构象将33个样本进行叠合并进行CoMFA与CoMSIA研究,均得到了较优的结果,其中以选用立体场、静电场和疏水场建立的CoMSIA模型结果最优,其主成分数,r2,q2（LOO）和r2pred分别为2, 0.894, 0.708和0.802. 构效关系模型分析显示基团的空间位阻、电性及疏水作用是影响活性的主要因素     

氨基乙内酰脲类BACE1抑制剂的特征结构与作用机制

对BACE1抑制剂的研究与开发已成为目前治疗阿尔兹海默症的主要研究方向之一。本文选取105个氨基乙内酰脲类BACE1抑制剂作为研究对象,借助比较分子相似性指数(Comparative Molecular Similarity Index, CoMSIA)和分子对接方法,建立定量构效关系预测模型,研究影响化合物抑制活性的特征结构信息,揭示该类抑制剂与靶标之间的作用模式。结果表明,模型(Q_²=0.45, R_²ncv=0.87, R_²pre=0.85)具有较强的预测能力,抑制剂主要占据了靶标的S3、S1和S2"位点,其主要作用力类型为氢键力。实验所得模型和信息可为日后研究开发新型高效的BACE1抑制剂提供一定的理论指导,节省研究时间与费用。     

马来酰胺类糖原合成酶激酶-3β抑制剂的分子对接和三维定量构效关系

通过分子对接和三维定量构效关系(3D-QSAR)两种方法来确定两类马来酰胺类的糖原合成酶激酶-3β(GSK-3β)抑制剂的结合方式.首先,用分子对接确定抑制剂与GSK-3β的结合模式及其相互作用;然后用比较分子力场分析法(CoMFA)与比较分子相似性指数分析法(CoMSIA)对48个化合物做三维定量构效关系的分析.两种方法得出的交互验证回归系数分别为0.669(CoMFA)和0.683(CoMSIA),证明该模型具有很好的统计相关性,同时也说明该模型具有较高的预测能力.根据该模型提供的信息,设计出9个预测性较好的分子.     

基于糖皮质激素受体调节剂波尼松龙的定量构效关系研究

为了探讨糖皮质激素受体调节剂波尼松龙系列的结构和活性之间的关系,首次使用比较分子力场(CoMFA)和比较分子相似性指数分析(CoMSIA)方法对77个靶标分子建立三维定量构效关系(3D-QSAR)模型.在基于配体叠合的基础上,得到了最好的CoMSIA模型(Q2=0.504,R2ncv=0.849,SEE=0.283,F=56.365和R2pred=0.792).模型的三维等势线图分析说明了疏水性基团在R1取代基位置有利于提高活性,亲水性基团在R2取代基位置有利于提高活性.此外,分子对接分析结果显示了与波尼松龙形成一些氢键的氨基酸Asn564,Gln642,Thr739在糖皮质激素受体调节剂中有重要作用.本文得到的结果能够更好地帮助理解糖皮质激素受体调节剂作用机理,并为今后的药物设计与合成提供了新思路.     

配合物{[Co(5-氨基-8-羟基喹啉)_2]·H_2O}_n的合成及结构研究

以4-[(8-羟基-5-喹啉)偶氮]-苯磺酸与氯化钴为原料,采用溶剂热法通过原位反应合成{[Co(5-氨基-8-羟基喹啉)_2]·H_2O}_n,并通过X-射线单晶衍射方法确定了该配合物的晶体结构.结构分析表明:标题配合物属于斜方晶系,Pbcn空间群,晶胞参数a=1.321(2)nm,b=0.811(2)nm,c=1.511(2)nm,α=β=γ=90.00°,V=1.619(3)nm~3,Z=4,R_1=0.0516,w R_2=0.1025.配合物中存在ππ堆积相互作用和氢键作用,将配合物连接形成三维超分子网络结构.     

由3D-QSAR、分子对接和分子动力学模拟研究吲唑类化合物与PI3Kδ抑制剂的相互作用

磷酸肌醇3-激酶δ(PI3Kδ)参与慢性阻塞性肺疾病的炎性过程并且被鉴定为一个新的潜在治疗靶点。本文采用三维定量构效关系(3D-QSAR)、分子对接和分子动力学方法研究了47个吲唑类化合物与P13Kδ激酶的相互作用,并建立了相应的模型。其中,比较分子场分析(CoMFA)模型q~2=0.719,r~2=0.972;比较分子相似性指数分析(CoMSIA)模型q~2=0.649,r~2=0.983,表明所建的QSAR模型具有稳定可靠的预测能力。CoMFA和CoMSIA等势图形象地描述了不同的场效应对活性的影响,其中立体场、疏水场及氢键受体场对活性有较大的贡献。接着采用分子对接探索小分子化合物与P13Kδ的结合模式,结合模式显示吲唑类化合物主要通过氢键作用与疏水作用与P13Kδ紧密结合,并且通过分子动力学模拟进一步验证了对接结果。最后根据等势图、对接模式和分子动力学模拟获取的信息设计了8个化合物,研究表明它们均能与PI3Kδ较好结合。     

[(QuinH)3Cl](I3)2的合成和分子结构

作者首次合成了单氯合三喹啉氢双三碘基盐[(QuinH)_3Cl](I_3)_2.用红外光谱、紫外—可见光谱法对化合物进行了表征,并用X射线衍射法测定了晶体结构.晶体属三斜晶系,空间群为P(?),a=12.349(2),b=12.878(2),c=11.679(2)(?),α=100.82(1)(?),β=109.02(1)(?),γ=89.58(1)(?),V=1721.8(?)~3,Z=2,D_c=2.29g·cm~(-3).化合物分子由[(QuinH)_3Cl]~(2+)阳离子和Г_3阴离子组成.在配位阳离子中.Cl~-由三个喹啉氢阳离子包围.同时形成三个Cl…H-N分子内氢键.     

MMPs抑制剂咖啡酸苯乙酯衍生物的3D-QSAR及分子对接研究

MMP-2是基底膜降解的关键酶,参与宫颈癌病发的整个过程,被认为是治疗宫颈癌的潜在新靶点。本文采用三维定量构效关系(3D-QSAR)研究32个咖啡酸苯乙酯类化合物与抗宫颈癌肿瘤细胞增殖活性的构效关系,通过比较分子场分析(CoMFA)模型(Q~2=0.638,R~2=0.972)及分子相似性指数分析(CoMSIA)模型(Q~2=0.665,R~2=0.975),表明所建立的QSAR模型具有稳定的预测能力。基于上述两种模型设计了18种新型咖啡酸苯乙酯类抑制剂,其中5种化合物具有较好的抗癌活性,抑制活性最强的为WS-1。将WS-1与MMP-2蛋白结合,结合模式显示WS-1主要通过氢键作用及疏水作用与MMP-2蛋白紧密结合,并能有效地占据MMP-2蛋白的结合位点。本研究构建的3D-QSAR模型也为进一步设计治疗宫颈癌其他抑制剂提供了理论参考。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.