N—取代苯基—N‘—（2—甲基苯氧乙酰基）氨基脲的合成及鉴定

以无机碱作催化剂,用不同的Ｎ－取代三氯乙酰苯胺与２－甲基苯氧乙酰肼反应,合成了５种取代氨基脲,产率达８２％以上。     

N—取代三氯乙酰胺合成新脲类化合物及其生物活性的研究：Ⅳ.1—呋喃酰？…

用Ｎ－取代三氯乙酰胺与呋喃甲酰胺肼反应，合成了６个新的１－呋喃酰基－４－芳基氨基脲。其结构经元素分析，ＩＲ和＾１Ｈ ＮＭＲ所证实。生物活性测试表明，其中某些化合物具有一定的除草活性。     

N-(取代苯基)-2-(对氯苯氧乙酰基)氨基脲的合成与表征

以无机碱为催化剂，用不同的Ｎ－（聚代基）三氯乙酰胺与对氯苯氧乙酰肼反应，首次合成了３种新的取代氨基基脲化合物Ｎ－（取代苯基）－２－（对氯苯氧乙酰基）氨基脲，产率７１％以上。     

过硫酸胺与N－［（3－二甲氨基）丙基］丙烯酰胺氧化还原引发体系的研究

过硫酸胺与Ｎ－［（３－二甲氨基）丙基］丙烯酰胺氧化还原引发体系的研究司堃，郭新秋，丘坤元（北京大学化学与分子工程学院北京１００８７１）关键词Ｎ－取代丙烯酰胺，氧化还原体系，反应动力学，端基分析，反应机理Ｎ－［（３一二甲氨基）两基］丙烯酸胺（ＤＭＡＰＡ...     

3－N－取代－5－氟脲嘧啶的制备新方法

报道了一种以Ｐｄ－Ｃ为催化剂，使２－苄氧基－３－Ｎ－取代－５－氟－４－嘧啶酮在室温常压下氢解制备３－Ｎ－取代－５－氟脲嘧啶的新方法，合成了８个３－Ｎ－取代－５－氟脲嘧啶化合物，其中有些化合物具有一定的抗肿瘤活性。     

3—N取代—5—氟脲嘧啶的制备新方法

报道了一种以Ｐｄ－ｃ为催化剂，使２－苄氧基－３－Ｎ－取代－５－氟－４－嘧啶酮在墁常压下氢解制备３－Ｎ－取代－５－氟脲嘧啶的新方法，合成了８个３－Ｎ－取代－５－氟脲嘧啶化合物，其中有些化合物具有一定的抗肿瘤活性。     

N－（N＇，N＇－二甲氨基甲基）丙烯酰胺－过硫酸钾引发丙烯酰胺聚合的研究

Ｎ－（Ｎ＇，Ｎ＇－二甲氨基甲基）丙烯酰胺－过硫酸钾引发丙烯酰胺聚合的研究潘松汉，唐康泰，王贞，王真智中国科学院广州化学研究所，广州，５１０６５０关键词Ｎ－（Ｎ＇，Ｎ＇－二甲氨基甲基）丙烯酰胺、反应动力学、氧化还原体系、相对分子质量及分布为了制备高质量...     

N-取代三氯乙酰胺合成新脲类化合物及其生物活性的研究 Ⅳ.1-呋喃酰基-4-芳基氨基脲的合成

用Ｎ－取代三氯乙酰胺与呋喃甲酰胺肼反应,合成了６个新的１－呋喃酰基－４－芳基氨基脲。其结构经元素分析,ＩＲ和１ＨＮＭＲ所证实。生物活性测试表明,其中某些化合物具有一定的除草活性     

N—取代三氯乙酰胺合成N,N“—多亚甲基双（N‘—（4—氯苯基）脲

通过Ｎ－取代三氯乙酰胺与不同的脂肪二胺反应，合成了５种新的Ｎ，Ｎ”－多亚甲基双（Ｎ’－（４－氯苯基）脲（ＡｒＮＨＣＯＮＨ（ＣＨ２）ｎＮＨＣＯＮＨＡｒ，ｎ＝２～６，Ａｒ＝４－ＣｌＣ６Ｈ４）其结构经元素分析，ＨＮＭＲ和ＩＲ证实。     

N－取代三氯乙酰胺合成N，N″－多亚甲基双［N′－（4－氯苯基）］脲

通过Ｎ－取代三氯乙酰胺与不同的脂肪二胺反应，合成了５种新的Ｎ，Ｎ″－多亚甲基双［Ｎ′－（４－氯苯基）］脲［ＡｒＮＨＣＯＮＨ（ＣＨ２）ｎＮＨＣＯＮＨＡｒ，ｎ＝２～６，Ａｒ＝４－ＣｌＣ６Ｈ４］，其结构经元素分析、１ＨＮＭＲ和ＩＲ证实     

Enantiomer separation by CEC——Enantiomer separation by packed-capillary electrochromatography

Three chiral compounds were successfully separated in a short time with two enantiomer separation models on packed-capillary electrochromatography (CEC). (i) 75 μm I.D. capillaries were packed with 5 μm β-cyclodextrin (β-CD) chiral stationary phase (CSP). Effects of voltage, pH and concentration of organic modifier on electroosmotic flow (EOF) and chiral separations were investigated systematically. Enantiomers of a neutral compound (benzoin) and a neutral drug (mephenytoin) were separated within a short time with high efficiency. Efficiency of 32 000 theoretical plates per meter and resolution (R_s) of 1.42 were achieved for enantiomers of benzoin using a βCD packed column with 6.2 cm packed length. Efficiency of 45 000 theoretical plates per meter and R_s of 3.40 were obtained for enantiomers of mephenytoin. Especially, the enantiomer separation of mephenytion was performed in just 3.4 min with R_s of 2.60. (ⅱ) 75 μm I.D. capillary was packed with octadecylsilica particles (ODS). Chiral separat     

Regioselectivity of olefin oxidation by iodosobenzene catalyzed by metalloporphyrins : control by the catalyst

The regioselectivity of the oxidation of three monosubstituted olefins, 6-phenoxyhex-1-ene, hex-1-ene and styrene, by iodosobenzene in the presence of various Fe-, Mn- or Cr-tetraaryl-porphyrins, was studied. It was found that, besides epoxides, known products from such systems, allylic alcohols and aldehydes were formed, the latter not being derived from the corresponding epoxides. The relative importance of these reactions greatly depends upon both the metal and porphyrin constituents of the catalyst. More particularly, the competition between epoxidation and allylic hydroxylation can be efficiently controlled by non-bonded interactions between the olefin and porphyrin substituents. No hydroxylation of the aromatic rings and no oxidative dealkylation of the ether function was detected.     

Glycosidase inhibition by macrolide antibiotics elucidated by STD-NMR spectroscopy

A glycosynthase approach was attempted to glycodiversify macrolide antibiotics, using DesR, a family-3 retaining beta-glucosidase involved in the self-resistance mechanism of methymycin production. STD-NMR was used to probe enzyme-substrate interactions. Analysis of competitive STD-NMR experiments between erythromycin A and a chromogenic substrate (pNP-beta-d-glucose) with the hydrolytically inactive nucleophile mutants led us to discover a family of unprecedented glycosidase inhibitors. Analysis of kinetic data with wild-type DesR determined that erythromycin is a competitive inhibitor of the glucosidase (IC50 = 2.8 +/- 0.3 microM and Ki = 2 +/- 0.2 microM) with respect to the hydrolysis of pNP-beta-d-glucose. Comparable inhibitory data was obtained for clarithromycin; however, the inhibitory effect of azithromycin was weak and no significant inhibition was observed with methymycin or d-desosamine. This report documents significant inhibition of glycosidases by macrolide antibiotics and provides insight into the design of novel glycosidase inhibitors based on the macrolactone ring of macrolide antibiotics.     

Membrane solubilization by detergent: resistance conferred by thickness

The commonly held model for membrane dissolution by detergents/surfactants requires lipid transport from the inner to the outer bilayer leaflet ('flip-flop'). Although applicable to many systems, it fails in cases where cross-bilayer transport of membrane components is suppressed. In this paper we investigate the mechanism for surfactant-induced solubilization of polymeric bilayers. To that end, we examine the dissolution of a series of increasingly thick, polymer-based vesicles (polymersomes) by a nonionic surfactant, Triton X-100, using dynamic light scattering. We find that increasing the bilayer thickness imparts better resistance to dissolution, so that the concentration required for solubilization, after a fixed amount of time, increases nearly linearly with membrane thickness. Combining our experimental data with a theoretical model, we show that the dominant mechanism for the surfactant-induced dissolution of polymeric vesicles, where polymer flip-flop across the membrane is suppressed, is the surfactant transport through the bilayer. This mechanism is different both qualitatively and quantitatively from the mechanisms by which surfactants dissolve pure lipid vesicles.     

Antibiotic recognition by binuclear metallo-beta-lactamases revealed by X-ray crystallography

Metallo-beta-lactamases are zinc-dependent enzymes responsible for resistance to beta-lactam antibiotics in a variety of host bacteria, usually Gram-negative species that act as opportunist pathogens. They hydrolyze all classes of beta-lactam antibiotics, including carbapenems, and escape the action of available beta-lactamase inhibitors. Efforts to develop effective inhibitors have been hampered by the lack of structural information regarding how these enzymes recognize and turn over beta-lactam substrates. We report here the crystal structure of the Stenotrophomonas maltophilia L1 enzyme in complex with the hydrolysis product of the 7alpha-methoxyoxacephem, moxalactam. The on-enzyme complex is a 3'-exo-methylene species generated by elimination of the 1-methyltetrazolyl-5-thiolate anion from the 3'-methyl group. Moxalactam binding to L1 involves direct interaction of the two active site zinc ions with the beta-lactam amide and C4 carboxylate, groups that are common to all beta-lactam substrates. The 7beta-[(4-hydroxyphenyl)malonyl]-amino substituent makes limited hydrophobic and hydrogen bonding contacts with the active site groove. The mode of binding provides strong evidence that a water molecule situated between the two metal ions is the most likely nucleophile in the hydrolytic reaction. These data suggest a reaction mechanism for metallo-beta-lactamases in which both metal ions contribute to catalysis by activating the bridging water/hydroxide nucleophile, polarizing the substrate amide bond for attack and stabilizing anionic nitrogen intermediates. The structure illustrates how a binuclear zinc site confers upon metallo-beta-lactamases the ability both to recognize and efficiently hydrolyze a wide variety of beta-lactam substrates.