16-脱氢孕烯醇酮醋酸酯的环境友好合成法

Instead of environmentally toxic chromium oxidant, singlet oxygen generated photcchemically was used as environmentally friendly and benign oxidizing agent to accomplish the transformation of pseudodiosgenin diacetate to diosone efficiently in a low toxic and less expensive solvent acetone. Accordingly 16-dehydropregnenolone acetate(16-DPA), an important intermediate for preparation of steroidal drugs, was prepared in good yield (75%) when photoreaction was run in acetone/acetic anhydride/pyridine system. The mild reaction condition as well as simple and environmentally friendly process made the method commercially viable and important for production of 16-DPA in industrial scale.     

A new type of symmetrical banana-shaped material based on N-methyldiphenylamine as a core moiety exhibiting an Ad→A2 transition

The synthesis and characterization of a homologous series of Schiff bases consisting of an N-methyldiphenylamine moiety as the central core is reported, which exhibits smectic A phase and transitions from the partial bilayer SmA_d phase to the bilayer SmA₂ phase as the temperature is lowered.     

Synthesis and characterization of an MRI Gd‐based probe designed to target the translocator protein

DPA‐713 is the lead compound of a recently reported pyrazolo[1,5‐a]pyrimidineacetamide series, targeting the translocator protein (TSPO 18 kDa), and as such, this structure, as well as closely related derivatives, have been already successfully used as positron emission tomography radioligands. On the basis of the pharmacological core of this ligands series, a new magnetic resonance imaging probe, coded DPA‐C₆‐(Gd)DOTAMA was designed and successfully synthesized in six steps and 13% overall yield from DPA‐713. The Gd‐DOTA monoamide cage (DOTA = 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid) represents the magnetic resonance imaging reporter, which is spaced from the phenylpyrazolo[1,5‐a]pyrimidineacetamide moiety (DPA‐713 motif) by a six carbon‐atom chain. DPA‐C₆‐(Gd)DOTAMA relaxometric characterization showed the typical behavior of a small‐sized molecule (relaxivity value: 6.02 mM^?1 s^?1 at 20 MHz). The good hydrophilicity of the metal chelate makes DPA‐C₆‐(Gd)DOTAMA soluble in water, affecting thus its biodistribution with respect to the parent lipophilic DPA‐713 molecule. For this reason, it was deemed of interest to load the probe to a large carrier in order to increase its residence lifetime in blood. Whereas DPA‐C₆‐(Gd)DOTAMA binds to serum albumin with a low affinity constant, it can be entrapped into liposomes (both in the membrane and in the inner aqueous cavity). The stability of the supramolecular adduct formed by the Gd‐complex and liposomes was assessed by a competition test with albumin. Copyright © 2013 John Wiley & Sons, Ltd.     

Total synthesis of 4-F3t-neuroprostane and its 4-epimer

The first synthesis of 4-F_3t-Neuroprostane 1a and its 4-epimer is described. This molecule presents an important contribution to the study of neuronal oxidative stress in DHA-ω3 depleted brain. The key step involves the introduction of two unsaturated side chains into the chiral polyfunctional cyclopentane 4 via E selective HWE reaction and Z selective Wittig olefination for α and ω chains, respectively.     

Optical probes for detection and quantification of neutrophils’ oxidative burst. A review

Neutrophils, also known as polymorphonuclear leukocytes (PMN), are the most common type of white blood cells, comprising about 50-70% of all white blood cells. In the event of inflammatory processes, neutrophils display increased mobility, tissue influx ability, prolonged life span, and an increased phagocytic capacity, constituting the initial participants in the cellular defense of the organism. One of the most important defense systems of neutrophils corresponds to their ability to mediate a strong oxidative burst through the formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). While oxidative burst is important for the elimination of invading microorganisms, the overproduction of ROS and RNS or the impairment of endogenous antioxidant defenses may result to detrimental effects to the host. The nature and the extent of ROS and RNS production by neutrophils in response to different stimuli is, consequently, a matter of extensive research, with scientific reports showing an enormous variability on the detection methodologies employed. This review attempts to provide a critical assessment of the most common approaches to identify and quantify reactive species formed during the neutrophils’ oxidative burst. The detection mechanisms and performance, as well as advantages and limitations of the different methodologies, are scrutinized, focusing on the use of fluorimetric, chemiluminometric and colorimetric probes.     

3－N，N－二甲基－1，3－丙二胺／冰醋酸催化下的Knoevenagel缩合反应

对硝基苯磺酰基乙腈与芳香醛在３－Ｎ，Ｎ－二甲基－１，３－丙二胺（ＤＰＡ）／冰醋酸催化下可顺利地发生Ｋｎｏｅｖｅｎａｇｅｌ缩合反应，生成２－（４－硝基苯磺酰基肉桂腈类化合物，产率８３％～９８％。但与水杨醛反应生成的产物是六元环内酯，其结构经元素分析、ＩＲ、￣１ＨＮＭＲ和ＭＳ确证。     

Study on polymerization and structure of polydiphenylamine

The electrochemical oxidation of diphenylamine in acetonitrile produces an adherent uniform polymer film which exhibits mutiple colour variation(yellow-green-blue) in a wide range of potential scan. The polymerization mechanism and the structure of the polymer were studied by cyclic voltammetry, FT-IR and in situ ESR. The results indicate that the electrochemical polymerization of diphenylamine belongs to a cationic radical polymerization process. During electrolysis, only oligomers were initialy produced, then polymer film was formed on the electrode surface. The electropolymerization performs via the 4,4' C-C phenyl-phenyl coupling mechanism.     

Stereoselective synthesis of farnesylphosphoryl β-d-arabinofuranose

Decaprenylphosphoryl β-d-arabinofuranose (DPA) is a key arabinose donor in mycobacteria. In an effort to establish a practical synthetic scheme for DPA, the synthesis of nerylphosphoryl and farnesylphosphoryl β-d-arabinofuranoses has been developed. The products were obtained by coupling of a suitably protected β-d-arabinofuranosyl phosphate intermediate with activated forms of the C₁₀ nerol and C₁₅trans,trans-farnesol and subsequent deprotection.     

DPA(TCNQ)2的烧孔阈值电压对脉宽的依赖关系

合成了一种新的二元电荷转移复合物DPA(TCNQ)2（二丙胺-7,7,8,8-四氰基对亚甲基苯醌)，并得到了其单晶ab面的STM高分辨图像，表面晶格常数与体相晶格常数的XRD数据完全一致.用STM成功地写入了5×5的信息点阵，并在5.1 μm×5.1 μm的面积上写入更大规模的信息点阵，写入的可靠性和稳定性都很高.实验发现，烧孔阈值电压强烈依赖于脉宽,这一现象不支持场致蒸发的机理.理论分析表明，它支持热化学烧孔的机理.     

3—N,N—二甲基—1,3—丙二胺／冰醋酸催化下的Knoevenagel缩合反应

对硝基苯磺酰基乙腈与芳香醛在３－Ｎ，Ｎ－二甲基－１，３－丙二胺（ＤＰＡ）／冰醋酸催化下可顺利地发生Ｋｎｏｅｖｅｎａｇｅｌ缩合反应，生成２－（４－硝基苯磺酰基肉桂腈类化合物，产率８３％～９８％。但与水杨醛反应生成的产物是六元环丙酯，其结构经元素分析，ＩＲ，ＨＮＭＲ和ＭＳ确证。