Ring-Enlargement of Dimethylaminopropenoyl Cyclopropanes: An Efficient Route to Substituted 2,3-Dihydrofurans

A convenient and efficient synthesis of substituted dihydrofurans is developed via ring-enlargement of 1-dimethylaminopropenoyl-1-carbamoyl/benzoyl cycloproparres catalyzed by ammonium acetate in acetic acid with high regio- and stereoselectivity. Some of the newly synthesized substituted dihydrofurans are subjected to further synthetic transformation in the presence of NaOH (aq) in ethanol to afford the corresponding 5-aryl-2,3-dihydrofuro[3,2-c]pyfidin-4(5H)-ones in high yields.

携带叠氮和氨侧基的脂肪族聚酯的合成和表征

含有功能侧基生物降解聚合物的制备在近几年中受到广大研究者的极大关注[1,2].目前已经通过环状碳酸酯与丙交酯(LA)和ε-己内酯(CL)等共聚的方法合成了带有羧基[3~5]和羟基[6,7]等的脂肪族聚酯,并在靶向载体、药物控释及组织工程方面得到了应用[2,8].但有关含侧链氨基的聚合物研究的报道很少,且主要集中在氨基酸NCA单体与LA的嵌段共聚方面[9,10],很少得到侧链氨基的无规共聚物.本文通过丙交酯(LA)与环状碳酸酯单体共聚的方法制备了一种侧链带有溴原子的脂肪族聚酯,并将溴原子用叠氮基团取代,通过Cu(Ⅰ)催化的Click反应将其氨基化,得到了侧链带有氨基的脂肪族聚酯.

1,2,3,4-Alternate double cone conformational extreme in the supramolecular assemblies of p-sulfonatocalix[8]arene

Two supramolecular assemblies of p-sulfonato-calix[8]arene were stacked by some infinite 1D 'molecular capsule' chains in which the calixarenes adopt an unprecedented 1,2,3,4-alternate double cone conformation.

Metal-organic frameworks based on the pyridine-2,3-dicarboxylate and a flexible bispyridyl ligand: syntheses, structures, and photoluminescence

Three new metal-organic coordination polymers, [Cu(2,3-pydc)(bpp)]center dot 2.5H(2)O (1), [Zn(2,3-pydc)(bpp)]center dot 2.5H(2)O (2) and [Cd(2,3-pydc)(bpp)(H2O)]center dot 3H(2)O (3) (2,3-pydcH(2) = pyridine-2,3-dicarboxylic acid, bpp 1,3-bis(4-pyridyl)propane), have been synthesized at room temvperature. All complexes have metal ions serving as 4-connected nodes but represent two quite different structural motifs. Complexes 1 and 2 are isomorphous, both of which feature 2D -> 3D parallel interpenetration. Each two-dimensional (2D) layer with (4, 4) topology is interlocked by two nearest neighbours, one above and one below, thus leading to an unusual 3D motif. Complex 3 has a non-interpenetrating 3D CdSO4 framework with cavities occupied by uncoordinated water molecules.

Efficient synthesis of trimethylsilyl-substituted dithieno[2,3-b:3',2'-d]thiophene,tetra[2,3-thienylene] and hexa[2,3-thienylene] from substituted [3,3']Bithiophenyl

Efficient synthetic procedures for the preparation of beta-trithiophenes (dithieno[2,3-b:3',2'-d]thiophene) and two macrocyclic compounds, tetra[2,3-thienylene] and hexa[2,3-thienylene] bearing trimethylsilyl (TMS) groups from 2,2'-dibromo-5,5'-bistrimethylsilanyl[3,3']bithiophenyl are reported. The UV-Vis spectra property and crystal structures of these macrocyclic oligothiophenes are described.

Synthesis and properties of novel polyimides derived from 2,2 ',3,3 '-benzophenonetetracarboxylic dianhydride

A new synthetic route to 2,2',3,3'-BTDA (where BTDA is benzophenonetetracarboxylic dianhydride), an isomer of 2,3',3',4'-BTDA and 3,3',4,4'-BTDA, is described. Single-crystal X-ray diffraction analysis of 2,2',3,3'-BTDA has shown that this dianhydride has a bent and noncoplanar structure. The polymerizations of 2,2',3,3'-BTDA with 4,4'-oxydianiline (ODA) and 4,4'-bis(4-aminophenoxy)benzene (TPEQ) have been investigated with a conventional two-step process. A trend of cyclic oligomers forming in the reaction of 2,2',3,3'-BTDA and ODA has been found and characterized with IR, NMR, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and elemental analyses. Films based on 2,2',3,3'-BTDA/TPEQ can only be obtained from corresponding polyimide (PI) solutions prepared by chemical imidization because those from their polyamic acids by thermal imidization are brittle. PIS from 2,2',3,3'-BTDA have lower inherent viscosities and worse thermal and mechanical properties than the corresponding 2,3',3',4'-BTDA- and 3,3',4,4'-BTDA-based PIs. PIs from 2,2',3,3'-BTDA and 2,3',3',4'-BTDA are amorphous, whereas those from 3,3',4,4'-BTDA have some crystallinity, according to wide-angle X-ray diffraction.

Synthesis and properties of polyimides derived from cis- and trans-1,2,3,4-cyclohexanetetracarboxylic dianhydrides

Cis-1,2,3,4-cyclohexanetetracarboxylic dianhydride (cis-1,2,3,4-CHDA) was synthesized. It was found that under such conditions as heating or boiling in acetic anhydride, cis-1,2,3,4-CHDA could be converted to its trans-isomer. The process of thermal isomerization was monitored by H-1 NMR spectra and the mechanism of conversion was proposed. Their absolute structures of cis- and trans-1,2,3,4-CHDAs were elucidated by single crystal X-ray diffraction. The polycondensations of cis- and trans-1,2,3,4-CHDAs with aromatic diamines such as 4,4'-oxydianiline (ODA), 4,4'-methylenedianiline (MDA), 4,4'-diamino-3,3'-dimethyldiphenylmethane (DMMDA), 4,4'-bis(4-aminophenoxy)benzene (TPEQ), 2,2-bis[4-(4-aminophenoxy)phenyl] propane (BAPP) were studied. It is easy to obtain higher molecular weight polyimides from trans-1,2,3,4-CHDA using conventional one-step or two-step methods. However, higher molecular weight polyimides derived from cis-1,2,3,4-CHDA could not be prepared by the usual methods (solid content ca. 10%) owing to the trend of forming cyclic oligomers.

Novel polyimides derived from 2,3,3 ',4 '-benzophenonetetracarboxylic dianhydride

A series of polyimides (PIs) based on 2,3,3',4'-benzophenonetetracarboxylic dianhydride (2,3,3',4'-BTDA) and 3,3',4,4'-BTDA were prepared by the conventional two-step process. The properties of the 2,3,3',4'-BTDA based polyimides were compared with those of polyimides prepared from 3,3',4,4'-BTDA. It was found that PIs from 2,3,3,4'-BTDA have higher glass transition temperature and better solubility without sacrificing their thermal properties. Furthermore the theological properties of PMR-15 type polyimide resins based on 2,3,3',4'-BTDA showed lower melt viscosity and wider melt flow region (flow window) compared with those from 3,3',4,4'-BTDA. The structure-property relations resulted from isomerism were discussed.

Preparation and gas sensitivity of octa-n-butoxy-2,3-naphthalocyanine copper(II) Langmuir-Blodgett film

The formation process of monolayer of octa-n-butoxy-2,3-naphthalocyanine copper ( I), [CuNc(OBu)(8)], on water subphase was studied. Its multilayers were successifully deposited on the hydrophilic substrates by Z-type deposition mode using LB technique. Stable solid film with a limiting molecular area of 0.74 nm(2) and a collapse pressure of 55 mN/m were formed. The LB film structure was characterized by IR and electronic absorption spectra. Macrocycle of CuNc (OBu)(8) molecules have a face-to-face arrangement in the multilayers. These films have good sensitivities to vapor of alcohols, with the following sequence of sensitivities: i-PrOH>EtOH>MeOH. The response time and recovery time of the LB films to vapor of MeOH, EtOH and i-PrOH[volume fraction (1-5) X 10(-5)] were within 2 and 5 seconds respectively, while those of the LB films to ammonia(1 X 10(-4)) were 30-60 seconds and 4-5 minutes respectively.

Relationship between chemical bond parameters and superconducting temperature in HgBa2Can-1CunO2n+2+delta (n=1, 2, 3, 4)

Bond covalency and valence of elements in HgBa2Can-1CunO2n+2+delta (n = 1, 2, 3, 4) were calculated and their relationship with T-c was discussed. For both oxygen and argon annealed samples, the results indicated that with the increase of n, the trend of bond covalency of Hg-O and Cu-O was the same or opposite compared with that of superconducting temperature. This may suggest that the magnitudes of Cu-O and Hg-O bond covalency are important in governing the superconducting temperature. For the highest T-c sample, Hg had the lowest valence, implying that lower valence of Hg was preferred in order to produce higher T-c. For fixed n, the valence of Cu in oxygen annealed samples was larger than that in argon annealed samples, indicating that oxygen annealed samples produced more carriers than argon annealed samples.

Valence of elements in HgBa2Can-1CunO2n+2+delta (n=1, 2, 3, 4)

Valence of elements in HgBa2Can-1CunO2n+2+delta (n=1, 2, 3, 4) (both argon and oxygen annealed samples) were calculated. The result indicated for both argon and oxygen annealed samples, Hg had the lowest valence for the highest T-c sample. For fixed n, the valence of Cu in oxygen annealed samples was larger than that in argon annealed samples, indicating that oxygen annealed samples produce more carriers than argon annealed samples.

三苯基锡-2-(1,2-亚乙二硫)亚甲基-3-羰基-5-芳基-4-戊烯酸酯的合成及晶体结构

由2-(1,2-亚乙二硫)亚甲基-3-羰基-5-芳基-4-戊烯酸与三苯基氢氧化锡反应,合成了九个标题化合物3.用X射线衍射法测定了3b的晶体结构.该晶体属三斜晶系,空间群Pl,α=0.9074(2)nm,b=1.6809(3)nm,c=2.1834(4)nm,α=77.57(3)°,β=88.04(3)°,γ=89.47(3)°,V=3.2503nm~3,Z=2;R=0.0592.由锡氧原子间距离可推测,该晶体中羧酸根作为双齿配体与锡原子形成了分子内五配位结构.

用激光解吸电离飞行时间质谱快速测定1H-2,3-二氢-1-吡咯里嗪酮衍生物的相对分子质量

采用激光解吸电离飞行时间质谱 (LDI TOF MS)快速测定了 1H 2 ,3 二氢 1 吡咯里嗪酮衍生物相对分子质量 ,初步总结了该类化合物的质谱规律 .实验中不需加入基质 ,实测值与理论计算值相吻合.

三环己基锡-2-(1,2-亚乙二硫)亚甲基-3-羰基-5-芳基-4-戊烯酸酯的结构研究

合成了 3个三环己基锡 -2 -( 1 ,2 -亚乙二硫 )亚甲基 -3-羰基 -5 -芳基 -4 -戊烯酸酯化合物 .用 IR,1 H NMR,1 3 C NMR和 1 1 9Sn NMR光谱及 X射线衍射对所合成的化合物进行了表征 .结果表明标题化合物为四配位、具有畸变四面体结构的锡酯类化合物