超声法合成3,4-二氢嘧啶-2(1H)-酮衍生物

以取代芳醛（1a~1h）,乙酰乙酸乙酯(2)和脲(3)为原料,MMT/CuCl₂为催化剂,乙醇为溶剂,在超声条件下经Beginelli反应合成了8个3,4-二氢嘧啶-2(1H)-酮衍生物（4a~4h）,其结构经¹H NMR和IR确证。以4a为例,分别采用单因素法和正交实验法研究了催化剂、溶剂、反应温度、超声时间和物料比r［n(1a): n(2) :n(3)］对4a产率的影响。结果表明：在最优反应条件(1a 2.4 mol, r=1.2 : 1.0 : 1.0, MMT/CuCl₂20 mol%, EtOH 1 mL,于90 ℃超声15 min)下,4a产率88.4%。 MMT/CuCl₂循环使用3次,产率基本不变。     

微波辐射促进选择性合成4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮和嘧啶-2(1H)-酮

探讨了在微波加热条件下,芳香醛、取代苯乙酮和尿素的三组分反应在N,N-二甲基甲酰胺(DMF)中制得4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮类化合物,收率为68%～84%.若在反应体系中加入三甲基氯硅烷,该三组分反应则高产率(66%～87%)地生成相应的脱氢产物4,6-二芳基嘧啶-2(1H)-酮类化合物.该反应具有反应条件温和、产物收率高、操作方便等优点,为4,6-二芳基-嘧啶-2(1H)-酮类药物中间体的合成提供了一条全新的路线.     

硝酸镧高效催化合成3,4-二氢嘧啶-2(1H)-(硫)酮

报道了以La(NO3)3催化芳香醛、β-酮酯和脲或硫脲-锅法合成3,4-二氢嘧啶-2(1H)-(硫)酮的简单、有效方法.与经典Biginelli反应条件相比,它具有产率高、反应时间短和操作简单等优点.所有目标化合物的结构经元素分析、IR、13C NMR和1H NMR确证.     

2-脲基-4[1氢]-嘧啶酮四氢键萘-蒽超分子组装体系:"通过键"机制的单重态能量传递

设计合成了基于2-脉基-4[1氢]-嘧啶酮AADD四氢键萘-葱超分子组装体系UPNa·UPAn.稳态和时间分辨荧光光谱研究表明UPNa·UPAn四氢键组装体可以发生从茶到葱的高效、快速的单重态能量传递过程.体系内光诱导单重态能量传递的速度和效率远大于通过F(o)rster机制的单重态能量传递速率,表明组装体系UPNa·...     

氯化亚锡催化“一锅法”合成N1-取代的3,4-二氢嘧啶-2(1H)-酮

以芳香醛、乙酰乙酸乙酯(甲酯)、单取代脲为原料,氯化亚锡为催化剂,在无溶剂、80℃条件下,通过三组分"一锅法"合成了一系列N1-取代的3,4-二氢嘧啶-2(1H)-酮衍生物。考察了催化剂用量和反应温度对产品收率的影响。通过IR、~1H NMR、~(13)C NMR和元素分析对目标产物结构进行确证,提出了可能的催化作用机理。本文的合成方法具有催化剂活性高、廉价易得和反应时间短、条件温和、产率高、绿色环保等优点。     

二氧化硅负载磷钨酸催化合成3,4-二氢嘧啶-2(1H)-酮衍生物

以取代苯甲醛、乙酰乙酸乙酯和尿素为原料,以溶胶凝胶法制备二氧化硅负载的磷钨酸（H3PW12O40/SiO2）为催化剂,催化合成3,4-二氢嘧啶-2(1H)-酮,考察了三组分摩尔比、反应温度、催化剂用量及反应时间对反应收率的影响。 研究表明,H3PW12O40/SiO2是合成3,4-二氢嘧啶-2(1H)-酮的良性催化剂,在取代苯甲醛的用量为0.04 mol,反应温度为90 ℃的条件下,收率可达73.1%~88.4%。 催化剂和产品结构分别经IR、XRD、SEM和1H NMR、IR、MS等技术手段表征。     

4(3H)-嘧啶酮及其类似物互变异构的理论研究

采用密度泛函理论,在B3LYP/6-311G**基组水平上,计算并考察了4(3H)-嘧啶酮及其类似物(5-氟-4(3H)-嘧啶酮、4-巯基嘧啶和5-氟-4-巯基嘧啶)醇式结构和酮式结构进行结构互变质子迁移过程中的2种可能途径:(a)分子内质子迁移;(b)水助质子迁移.计算结果表明,途经b所需要的活化能较小.研究还表明,氢键在降低反应活化能方面起着重要的作用.     

4-(4-吡啶基)嘧啶-2-磺酸钠与过渡金属组装的三维氢键网络结构

4-(4-吡啶基)嘧啶-2-磺酸钠(NaL²)与金属盐(M=Mn,Zn,Co,Fe)组装分别得到4个配合物,其分子式为[ML₂·4H₂O]·2H₂O。氢键在这些化合物的超分子结构中起了重要作用。4种配合物中磺酸基的氧原子没有螯合金属离子,而是作为氢键的受体,同时水分子作为氢键给体和受体起到双重作用。另外,在配合物2～4中,杂环上的碳原子也起到供体的作用与磺酸基的氧原子形成氢键。     

新型2-氨基-呋喃并[2,3-d]嘧啶-4(3H)-酮衍生物的合成及抗肿瘤活性

报道应用aza-Wittig反应,采用易得的原料,在温和的条件下,以78%～90%的产率有效的合成了新型2-氨基-呋喃并[3,2-d]嘧啶-4(3H)-酮衍生物5,其结构经IR,1H NMR,MS和元素分析确认.为进一步得到结构确认,化合物5c经X射线衍射分析证实.运用噻唑蓝(MTT)标准法对化合物5进行了体外抗肿瘤活性的测定,其中5f对肺癌细胞A459的IC50值为18.4μmol/L,显示出潜在良好的抗肿瘤活性.     

3,4-二氢-1-(4-哌啶基)-2(1H)-喹啉酮的合成

以苄胺为原料,经6步反应得到新型抗高血压药OPC-21268的中间体3,4-二氢-1-(4-哌啶基)-2(1H)-喹啉酮,总收率13．9％．     

Photoinduced triplet-triplet energy transfer via the 2-ureido-4[1H]-pyrimidinone self-complementary quadruple hydrogen-bonded module

Phosphorescence quenching and flash photolysis experiments demonstrate that photoinduced intra-assembly triplet-triplet energy transfer can take place via a 2-ureido-4[1H]-pyrimidinone-bridged benzophenone-naphthalene assembly I with a rate constant of 3.0 x 106 s-1 and an efficiency of 95% in CH2Cl2. This new finding suggests that with high binding strength and directionality, the 2-ureido-4[1H]-pyrimidinone hydrogen-bonded module may serve as a new model to illustrate the fundamental principles governing the triplet-triplet energy-transfer process through hydrogen bonds.     

Inner-assembly singlet energy transfer in naphthalene-anthracene system linked by 2-ureido-4{1H}-pyrimidinone binding module

Naphthalene-naphthalene, anthracene-anthracene, and naphthalene-anthracene assemblies 1.1, 2.2, and 1.2 linked by 2-ureido-4{1H}-pyrimidinone binding module were synthesized. Fluorescence quenching and lifetime measurements demonstrate that the inner-assembly singlet energy transfer from naphthalene to anthracene in 1.2 occurs with the efficiency of ca. 89% and rate constant of ca. 9.8 × 10⁸ s⁻¹. Föster energy transfer mechanism operates in this energy transfer process.     

First fluorescent sensor for fluoride based on 2-ureido-4[1H]-pyrimidinone quadruple hydrogen-bonded AADD supramolecular assembly

A simple, highly selective, neutral, fluorescent sensor for fluoride anions is reported. It is based on 2-ureido-4[1H]-pyrimidinone quadruple hydrogen-bonded AADD supramolecular assembly, and its assembling and disassembling processes are also able to respond to external stimuli reversibly.     

结构受阻对取代苯乙烯基吡嗪光物理行为的影响

有关藻类化合物衍生物的荧光发光及其顺反异构化是长期来一直受到广泛注意的问题［’，2］，近年来特别在发现了街的两侧苯环联有推、拉电子能力基团、构成了分子内共轭的电行转移化合物后，其荧光发射有了较大幅度的增长［3，4］，使人们对这一问题的研究更加关切．由于荧光的增长会导致异构化反应的减少，促使人们提出所谓的激发态多衰变通道的观点［5，6］以激发的英分子为例；已认识到其中的双键扭转应为异构化（无辐射衰变的一种）的主要通道，而蔑分子的平面态或双键二侧单键的扭转态则是荧光发射（辐射衰变）的主要途径·所有这些看…     

Self-assembled pentamers and hexamers linked through quadruple-hydrogen-bonded 2-ureido-4[1H]-pyrimidinones

The preorganization of bifunctional 2-ureido-4-pyrimidinones mediated by either 1,3-substituted adamantane or meta-substituted phenylene ring linkers leads to the preferred formation of stable pentameric (1)(5) and hexameric (2)(6) assemblies, respectively. Despite the high binding constant of the 2-ureido-4-pyrimidinone dimers and the highly preorganized structure of the monomer, the predominant formation of cycles (1)(5) and (2)(6) in solution occurs only within a specific concentration range.     

Synthesis and reactions of [tris(trimethylsilyl)methyl]ethyl dichlorosilane

The crowded dichlorosilane TsiSiEtCl₂, (1), (Tsi = (Me₃Si)₃C) was prepared from the reaction between EtSiCl₃ and TsiLi, then it was reduced with LiAlH₄ to give TsiSiEtH₂, (2). The hydride (2) was then treated with two equivalents of ICl/CCl₄ or Br₂/CCl₄ to produce TsiSiEtI₂, (3), and TsiSiEtBr₂, (4), respectively. The reaction of compound (2) with one equivalent of ICl/CCl₄ gives TsiSiEtHI, (5). This product reacted with H₂O/dioxane in the presence of AgClO₄ or with dry MeOH to produce TsiSiEtHOH, (6), and TsiSiEtHOMe, (7), respectively. The compound (3) reacted with H₂O in DMSO/CH₃CN to give TsiSiEt(OH)₂, (8), and the compound TsiSiEtIOMe, (9), was prepared from the reaction of the compound (7) with ICl/CCl₄. When the dichloride (1) was treated with NaOMe/MeOH it gave (Me₃Si)₂CHSiEt(OMe)₂. It is suggested that the reaction proceeds through an elimination-addition mechanism. The dichloride (1) was also treated with KSCN, NaN₃ or NaOCN in CH₃CN to give S_N2 substitution products. All the new products were characterized by FTIR, ¹H NMR, and ¹³C NMR spectroscopy, mass spectrometry and elemental analysis.     

The First Intramolecular Charge Transfer Transition Based on 2-Ureido-4[1H]-pyrimidinone Binding Module

The first intramolecular charge transfer transition based on 2-ureido-4[1H]-pyrimidinone binding module was reported.     

Acid catalysed methanolysis of 2,5-diazabicyclo[2.2.2]octane-3,6-diones: scope and limitations

The selective methanolysis of 2,5-diazabicyclo[2.2.2]octane-3,6-dione systems is a key step in a synthetic procedure leading to 4-amino-6-oxo-2-piperidinecarboxylate systems. This reaction seems to be primarily governed by steric hindrance caused by the substituents at the 1- and 4-bridgehead positions of the dione. In absence of bulky substituents the methanolysis is directed by the secondary or tertiary nature of the two lactam moieties.     

Super-tough and rapidly self-recoverable multi-bond network hydrogels facilitated by 2-ureido-4[1H]-pyrimidone dimers

Multi-bond network(MBN) hydrogels contain hierarchical dynamic bonds with different bond association energy as energy dissipation units,enabling super-tough mechanical properties.In this work,we copolymerize a protonated 2-ureido-4[1 H]-pyrimidone(UPy)-contained monomer with acrylic acid in HCl solution.After removing excess HCl,UPy motifs are deprotonated and from dimers,thus generating an UPy-contained MBN hydrogel.The obtained MBN hydrogels(75 wt% watercontent) exhibit super-tough mechanical properties(0.39 MPa to 2.51 MPa tensile strength),with tremendous amount of energy(1.68 MJ/m³ to 11.1 MJ/m³) dissipated by the dissociation of UPy dimers.The introduction of ionic bonds can further improve the mechanical properties.Moreover,owing to their dynamic nature,both UPy dimers and ionic bonds can re-associate after being dissociated,resulting in excellent self-recovery ability(around 90% recovery efficiency within only 1 h).The excellent self-recovery ability mainly originates from the re-association of UPy dimers based on the high dimerization constant of UPy motifs.     

Effect of Substituents on Aggregation Behaviors of Stilbazole and Stilbazolium Derivatives

Stilbazole and stilbazolium derivatives with dialkylaniline as electron pushing substituents and pyridine or pyridinium substituents as electron drawing substituents were synthesized and their aggregation behaviors were studied by UV‐visible, fluorescence and surface photovoltage spectroscopies. Experimental results indicate that the formation of aggregates can be mediated by the electron drawing ability of the substituents introduced for those compounds all bearing strong electron pushing substituent. When the electron drawing substituent is pyridine group, the molecules tend to aggregate in head‐to‐tail manner, whereas the substituent is pyridinium group, the molecules tend to aggregate in face‐to‐face manner. The effect of electron pushing and drawing ability of the substituents on the aggregation behavior is further analyzed in terms of frontier orbital interactions.