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·...     

取代基对2-脲基-4(1H)-嘧啶酮衍生物聚集行为的影响

UPy结构上的6位取代基会影响UPy结构上的离域π电子云的密度,6位取代基的给电子诱导效应越强,π电子云的密度越大,四重氢键的作用越强。脲基嘧啶酮结构即UPy结构的二聚体存在着最低的势能,表明该结构在体系内最为稳定。随着嘧啶环上的电子云密度增加,离域π键间的电子斥力增强,(001)晶面间距d逐渐增大。异氰酸酯结构的空间位阻的增大会阻碍UPy中的氢原子与相邻的嘧啶酮之间的接触,使得氢键作用强度减弱,同时较大的空间位阻会阻碍嘧啶环间的π–π相互作用,使得(001)晶面间距增大。     

取代基对2-脲基-4(1H)-嘧啶酮衍生物聚集行为的影响

2-脲基-4(1H)-嘧啶酮(UPy)结构上的6位取代基会影响UPy的离域π电子云的密度,6位取代基的给电子诱导效应越强,π电子云的密度越大,四重氢键的作用越强。脲基嘧啶酮结构即UPy结构的二聚体的势能最低,表明该结构在体系内最为稳定。随着嘧啶环上的电子云密度增加,离域π键间的电子斥力增强,(001)晶面间距逐渐增大。异氰酸酯结构的空间位阻增大会阻碍UPy中氢原子与相邻嘧啶酮之间的接触,使得氢键作用强度减弱;同时,较大的空间位阻会阻碍嘧啶环间的π-π相互作用,使得(001)晶面间距增大。     

高氯酸镁催化合成1,2,3,4-四氢嘧啶-2-酮

在高氯酸镁催化作用下,由醛、1,3-二羰基化合物、脲(硫脲)合成了一系列1,2,3,4-四氢嘧啶-2-酮,此合成方法反应温和、产率高,并且高氯酸镁具有能重复使用的优点.     

研磨法合成1,2,3,6-四氢嘧啶-2-酮衍生物

以NH₂SO₃H为催化剂, 室温无溶剂条件下, 研磨芳醛、β-酮酸酯和尿素合成了一系列1,2,3,6-四氢嘧啶-2-酮衍生物. 该方法具有反应条件温和、操作简便、环境友好、产率高等优点.     

用聚乙二醇简便合成3-取代-1, 2, 3, 4-四氢吡啶并[3, 2-d]嘧啶-2, 4-二酮

用聚乙二醇作为可溶性聚合物载体和相转移催化剂高效简单的合成了1, 2, 3, 4-四氢吡啶并[3, 2-d]嘧啶类化合物。该合成路线为聚乙二醇与2, 3-吡啶二酸酐反应生成聚乙二醇支载的单酯1,接着1被转化成相应的聚乙二醇支载的酰基叠氮2,2经Curtius重排,与胺加成并同时关环给出目标产物,其总产率为84%-88%。     

3, 4-二氢嘧啶-2-酮衍生物合成研究进展

综述了近十年来3,4-二氢嘧啶-2-酮衍生物合成的研究进展,包括催化合成、固相合成、微波促进合成及天然产物合成中的一些最新研究进展。     

选择性合成双[噻吩并[2,3-d]嘧啶-4(3H)-酮]

以2-氨基-4-三氟甲基-5-甲基-噻吩-3-羧酸乙酯(1)为起始原料制得膦亚胺2.在碳酸钾的催化下,膦亚胺2与芳基异氰酸酯和伯二胺的氮杂Wittig反应制得嘧啶环上2,2’取代的双[噻吩并[2,3-d]嘧啶-4(3H)-酮]3;膦亚胺2与烷基异氰酸酯和伯二胺的氮杂Wittig反应制得嘧啶环上3,3’取代的双[噻吩并[2,3-d]嘧啶-4(3H)-酮]4.化合物3的核磁共振氢谱表明关环反应在嘧啶环的2,2’位;化合物4的核磁共振氢谱表明关环反应在嘧啶环的3,3’位.对合成反应机理的推导及目标产物核磁共振氢谱数据的分析解释了此合成反应的选择性.     

嘧啶的研究:氯对硫醇嘧啶的作用2-酮-4-氨基-5,6-二甲基-1,2-二氢-嘧啶的合成

1.甲醇鈉對於2-乙硫醇基-4,5-二甲基-6-氯代嘧啶在甲醇溶液中生成相應的乙硫醇基嘧啶甲醚。 2.氯對於2-乙硫醇基-4,5-二甲基嘧啶衍生物(I),在水溶液中的作用是特殊的,嘧啶中的不飽和現象不被氯化反應改變而硫醇基團被氧化,形成穩定相應嘧啶碸的衍生物(II),因此製備了2-乙磺醯基-4,5-二甲基-6-甲氧基嘧啶和2-乙磺醯基-4,5-二甲基-6-氯代嘧啶. 3.2-乙硫醇-4,5-二甲基-6-甲氧基嘧啶在甲醇中進行氯化反應,現象甚複雜,並且嘧啶碸的產量很低,2-乙硫醇-4,5-二甲基-6-甲氧基嘧啶在甲醇中被氯氧化,首先形成嘧啶碸,後者並不穩定,再與氯作用形成乙磺醯氯和2-氯代-4,5-二甲基-6-甲氧基嘧啶。 4.嘧啶碸與鹼作用,乙磺醯基被羥基取代,同時在嘧啶環6位上的乙氧基保留,因此2-乙磺醯基-6-甲氧基-4,5-二甲基嘧啶與鹼作用,形成2-酮-5,6-二甲基-4-甲氧基-1,2-二氫嘧啶。 5.酒精-氨的溶液作用在氯代乙磺醯基嘧啶得到氨基-乙磺醯基嘧啶,在氯代乙磺醯基嘧啶中,嘧啶環上2位的乙磺醯基仍保留,而6位土的氯被氨基取代。 6.本文敘述了合成4,5-二甲基-2-氧代-6-氨基嘧啶(或2-酮-4-氨基-5,6-二甲基-1,2-二氫化嘧啶)的新方法。     

萘基薁并[2,1-d]嘧啶-4-胺类衍生物的合成

研究了萘基薁并[2,1-d]嘧啶-4-胺类衍生物的合成方法.以托酚酮、萘乙酸乙酯、N,N-二甲基甲酰胺二甲缩醛(DMF-DMA)及芳香胺为原料,依次经过氯代、缩合、环加成、环化反应得到目标产物.该反应操作简单、条件温和、收率良好.产物的结构经1H NMR,IR及元素分析等得以证实.     

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.     

Preparation and Characterization of Attractive Poly(amino acid)Hydrogels Based on 2-Ureido-4[1H]-pyrimidinone

Self-healing hydrogels with the shear-thinning property are novel injectable materials and are superior to traditional injectable hydrogels.The self-healing hydrogels based on 2-ureido-4[1 H]-pyrimidinone(UPy)have recently received extensive attention due to their dynamic reversibility of UPy dimerization.However,generally,UPy-based self-healing hydrogels exhibit poor stability,cannot degrade in vivo and can hardly be excreted from the body,which considerably limit their bio-application.Here,using poly(l-glutamic acid)(PLGA)as biodegradable matrix,branchingα-hydroxy-ω-amino poly(ethylene oxide)(HAPEO)as bridging molecule to introduce UPy,and ethyl acrylate polyethylene glycol(MAPEG)to introduce double bond,the hydrogel precursors(PMHU)are prepared.A library of the self-healing hydrogels has been achieved with well self-healable and shear-thinning properties.With the increase of MAPEG grafting ratio,the storage modulus of the self-healing hydrogels decreases.The self-healing hydrogels are stable in solution only for 6 h,hard to meet the requirements of tissue regeneration.Consequently,ultraviolet(UV)photo-crosslinking is involved to obtain the dual crosslinking hydrogels with enhanced mechanical properties and stability.When MAPEG grafting ratio is 35.5%,the dual crosslinking hydrogels can maintain the shape in phosphate-buffered saline solution(PBS)for at least 8 days.Loading with adipose-derived stem cell spheroids,the self-healing hydrogels are injected and self-heal to a whole,and then they are crosslinked in situ via UV-irradiation,obtaining the dual crosslinking hydrogels/cell spheroids complex with cell viability of 86.7%±6.0%,which demonstrates excellent injectability,subcutaneous gelatinization,and biocompatibility of hydrogels as cell carriers.The novel PMHU hydrogels crosslinked by quadruple hydrogen bonding and then dual photo-crosslinking of double bond are expected to be applied for minimal invasive surgery or therapies in tissue engineering.     

新型苯并香豆素醛的设计合成及光物理性质研究

设计合成了具有较长发射波长的苯并香豆素醛--8-二乙氨基-2-氧-2H-苯并香豆素醛(BCA),通过吸收和荧光光谱研究其在不同溶剂中的光物理性质.结果表明,BCA具有明显的溶致变色效应和宽的颜色变化范围.随着溶剂极性的增加,其荧光发射可从蓝绿光变到红光,而荧光量子效率则从0.98减小到0.26.     

Lower Rim-Upper Rim Hydrogen-Bonded Adducts of Calix[4]arenes

An upper-rim-substituted calix[4]arene tetracarboxylic acid forms hydrogen-bonded duplexes with lower-rim-substituted tetra(4-pyridyl)- and tetra(3-pyridyl)calix[4]arenes in chloroform. The formation of these adducts was studied by extraction experiments. The association constants determined via (1)H NMR dilution experiments in CDCl(3) are 7.6 x 10(3) and 1.3 x 10(3) M(-1) for the 4-pyridyl and the 3-pyridyl derivative, respectively. IR studies in the solid state and in solution indicate that the interaction is based on hydrogen bonding and that the degree of proton transfer is negligible. VPO measurements support the formation of 1:1 adducts.     

Mn4-硫杂杯[4]芳烃单元的溶剂导向超分子组装

以去叔丁基硫杂杯[4]芳烃与Mn(II)为研究对象,通过改变体系溶剂分别得到了两个四核化合物Mn4(T4A)2 (1)和Mn4(T4A)2(DMF)2(2) (T4A = thiacalix[4]arene)。当反应溶剂为氯仿(CHCl3)和甲醇的混合溶剂时,形成的是以四核锰为结构单元的二维“笼目”(Kagomé)状超分子化合物1,而当反应溶剂为N,N-二甲基甲酰胺(DMF)和甲醇的混合溶剂时,得到的是格子状二维超分子互穿的三维结构化合物2。化合物1具有很大的溶剂占有空隙,是一个潜在的多孔材料,而化合物2是一个紧密堆积的拓展结构。     

Novel intramolecular [4 + 1] and [4 + 2] annulation reactions employing cascade radical cyclizations

Tributyltin hydride and tris(trimethylsilyl)silane promote sequential/cascade free radical cyclization reactions of dienoate tethered vinyliodides or alkynes. These processes produce [4 + 1] and [4 + 2] annulated products. In contrast, the electrochemical reductions of the vinyliodides afford monocyclic compounds. Both the regiochemical and stereochemical courses of the sequential radical cyclizations strongly depend on substrate structure. Especially important is the balance between steric and stereoelectronic (Baldwin's rules) factors that serve to control cyclization regiochemistry.