乙酸功能化离子液体作为高效、可回收的催化剂用于2-萘酚与芳醛缩合反应(英文)

An efficient solvent‐free protocol for the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes from the condensation of 2‐naphthol with arylaldehydes, using acetic acid functionalized imidazolium salts (1‐carboxymethyl‐3‐methylimidazolium bromide ([cmmim]Br) and 1‐carboxymethy1‐3-me-thylimidazolium tetrafluoroborate([cmmim]BF4) as reusable catalysts, has been developed. The turn over frequency on the catalysts is several times higher than the other previously reported catalysts. Also, thermal gravimetric analysis and powder X‐ray diffraction pattern of the catalysts have been studied.     

Rapid stereoselective access to the tetracyclic core of puupehenone and related sponge metabolites using metal-free radical cyclisations of cyclohexenyl-substituted 3-bromochroman-4-ones

The tetracyclic nucleus of puupehenone, 15-oxopuupehenol and other sesquiterpene-phenol natural products can be assembled stereoselectively in three steps, the last of these being the 6-endo-trig cyclisation of an alpha-keto radical generated from a substituted 2-(2-cyclohexenyl)ethyl 3-bromo-4-chromanone under metal-free conditions.     

Optically high transparency and light color of organosoluble fluorinated polyamides with bulky xanthene pendent groups

New fluorinated polyamides were prepared directly from a diamine, 9,9‐bis[4‐(2‐trifluoromethyl‐4‐aminophenoxy)phenyl]xanthene ( BTFAPX ) with various aromatic dicarboxylic acid chlorides by low‐temperature polycondensation. The polymers were produced with moderate‐to‐high inherent viscosities of 0.65–1.01 dl/g while the weight‐average molecular weight and number‐average molecular weight were in the range of 69,000–82,000 and 39,000–43,000, respectively. Nearly all the polymers were readily soluble in amide‐type polar aprotic solvents [e.g. N, N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidinone], and even in less polar solvents such as dimethyl sulfoxide and pyridine, and afforded transparent, light‐colored, and flexible films upon casting from DMAc solvent. The polymers showed glass transition temperatures between 235 and 284°C, and 10% weight loss temperatures ranging from 495 to 532°C and 476 to 510°C in nitrogen and air, respectively, and char yields higher than 55% at 800°C in nitrogen. All polymers were amorphous and their films exhibited tensile strengths of 64–95 MPa, elongations at break of 6–9%, and tensile moduli of 1.9–2.5 GPa. These polymers had dielectric constants ranging from 3.65 to 4.03 (100 Hz), low‐moisture absorption in the range of 0.56–1.14%, and high transparency with an ultraviolet–visible absorption cut‐off wavelength in the 334–372 nm range. Copyright © 2010 John Wiley & Sons, Ltd.     

呫吨类抗胆碱能化合物的合成研究

呫吨羟基羧酸酯类化合物是一类新型高效的抗胆碱、抗梭曼化合物, 比以往的抗胆碱药物效价有较大幅度的提高,设计合成了一系列新的9-羟基-9-呫吨羧酸酯类抗胆碱化合物. 在合成环状基团的过程中, 探索了取代呫吨环中间体的合成路线; 在氨基醇的合成过程中, 采用10%的Pd/C作催化剂, 并将H2的压力下降到30 kg/cm2, 产率提高到90%, 优化了催化氢化的反应条件; 在目标化合物的合成过程中, 改进了产物的纯化和后处理方法, 简化了操作步骤.     

无催化剂条件下经微波辐射一步合成9-芳基-3,4,5,6,7,9-六氢-1H-氧杂蒽-1,8(2H)-二酮

微波辐射下以芳醛、1,3-环己二酮为原料在无催化剂条件下合成了一系列9-芳基-3,4,5,6,7,9-六氢-1H-氧杂蒽-1,8(2H)-二酮, 该反应时间短、产率高、后处理方便、环境友好.     

无外加催化剂条件下邻取代芳香醛与5,5-二甲基-1,3-环己二酮的反应研究

在DMF溶剂中,不外加催化剂使邻取代芳香醛(1)与5,5-二甲基-1,3-环己三酮(2)发生缩合和加成反应生成3,3,6,6-四甲基-4a-羟基-9-芳基-1,8二氧化-2,3,4,4a,5,6,7,8,9a-十氢化-1H氧杂蒽(3a～3d)。在同样条件下,邻羟基芳香醛与5,5-二甲基-1,3-环己三酮则发生缩合,加成和脱水反应生成3,3-二甲基-9-(5,5-二甲基-3-羟基-2-环己烯-1-酮-2-基)-1-氧代-2,3,4,9-四氢化-1 氧杂蒽(4a～4b)。用单晶X-射线分析法确定了产物3a和4a的晶体结构。     

Highly Sensitive Spectrophotometric Determination of Trace Amounts of Uranium ( Ⅵ ) with Thiocyanate-Basic Xanthene Dye-Gum Arabic Systems

Spectrophotometric determination of molybdenum, zinc, cobalt(Ⅱ), indium, selenium (Ⅳ), iron (Ⅲ), vanadium (Ⅴ), which is based on the ion-associate complexes formed by the reaction of metal ion-thiocyanate anionic complexes with some basic dyes in aqueous solution in the presence of a surfactant has been reported.     

Fundamental Aspects of Xanthene Dye Aggregation on the Surfaces of Nanocluster Polyoxometalates: H- to J-Aggregate Switching

The induced aggregation of the xanthene dye rhodamine B (RhB) on metal oxide centers belonging to the highly symmetric surfaces of precise nanoscale templates with Keplerate (Mo₁₃₂) or toroidal (Mo₁₃₈) structures has been studied. With the joint use of the Langmuir isotherm and full Stern–Volmer models, the thermodynamic reasons for dye adsorption on the nanocluster surface, such as a mixture of monomer, H-aggregate (H-dimer), and J-aggregate forms (which can coexist or switch one into another under the exact conditions), were established: this was shown through UV/Vis and fluorescence spectroscopies. By using the framework of the exciton model, it is shown that the angle (α) between the transition dipole moments of RhB is very sensitive to surface strain inside the dye sub-monolayer. As a result, it is possible to switch from H- to J-aggregates by the post-functionalization of polyoxometalate (POM)-RhB associates by the surfactant bilayer shell, which allows the surface strain to grow. Recommendations are provided for managing the appearance of H- or J-aggregates on metal oxide (or polyelectrolyte) surfaces during photovoltaic or bioimaging applications.     

Development of an AND Logic‐Gate‐Type Fluorescent Probe for Ratiometric Imaging of Autolysosome in Cell Autophagy

The concomitant detection of two biological events facilitates the highly selective and sensitive analysis of specific biological functions. In this article, we report an AND logic‐gate‐type fluorescent probe that can concurrently sense two biological events in living cells: H₂O₂ accumulation and acidification. The probe exhibits a unique fluorescence sensing mechanism, in which a xanthene fluorophore is oxidatively transformed to a xanthone derivative by H₂O₂, thereby resulting in a clear dual‐emission change. This transformation is significantly accelerated under weak acidic conditions, which enables the selective and sensitive detection of H₂O₂ production in an acidic cellular compartment. This unique sensing property was successfully applied to the ratiometric fluorescence imaging of autolysosome formation in selective mitochondrial autophagy (mitophagy), which highlights the utility of this novel probe in autophagy research.