Synthesis and Antibacterial Activity of Novel Oxazolidinone Analogs Containing Substituted Thiazole/Fused-Bicyclic Groups

IntroductionOxazolidinones, exemplified by linezolid, are anovel class of totally synthetic antibacterial agents withactivities against a variety of clinically important sus-ceptible and resistant Gram-positive pathogenic bacteriasuch as methicillin-resis…     

Synthesis and structure-activity relationship of rhodomyrtone derivatives as antibacterial agent

To study structure-activity relationship of rhodomyrtone against Gram-positive bacteria,structural modification of rhodo-myrtone was carried out to afford its 10 analogues.All compounds were assayed for their antibacterial potency using broth microdilution method.The results indicated that rhodomyrtone exhibited higher antibacterial activity against all Gram-positive bacteria than its analogues,with the exception of rhodomyrtone 6,8-diacetate(3) and oxime analogues 6 and 7 which demonstrated similar activity as the parent compound against Bacillus subtilis and Staphylococcus epidermidis with minimum inhibitory concentration and minimum bactericidal concentration ranged from 1 to 4μg/mL and 2 to 4μg/mL,respectively.In contrast,all analogues displayed no activity against Acinetobacter baumannii.Hydroxyl and ketone groups of rhodomyrtone were elucidated to be essential for the antibacterial property.     

Design,synthesis and antibacterial activity of novel 1-oxacephem analogs

A series of l-oxacephem analogs were synthesized and their antibacterial properties against five strains of Gram-positive and Gram-negative bacteria were evaluated in vitro while ceftazidine was selected as control. Some of the tested compounds, compound 2c in narticular,showed more active aeainst three selected strains than the standard.     

THE SEPARATION,PURIFICATION AND DECOLORIZATION OF NEW ANTIBIOTICS-MILUPEINAN USING ADSORPTION RESIN

1. INTRODUCTION Fig.1 The Chemical Structure of Milupeinan As a new type of antibiotics Milupeinan, not only possesses antibacterial activities against a wide range of Gram-positive and Gram-negative bacteria, but also higgh stability under th…     

Synthesis and biological activities of thio-triazole derivatives as novel potential antibacterial and antifungal agents

A series of novel thio-triazole derivatives including thiols, thioethers and thiones as well as some corresponding triazolium compounds were conveniently and efficiently synthesized from commercially available halobenzyl halides and thiosemicarbazide. All the new compounds were characterized by 1 H NMR, 13 C NMR, FTIR, MS and HRMS spectra. Their antibacterial and antifungal activities in vitro were evaluated against four Gram-positive bacteria, four Gram-negative bacteria and two fungi by two-fold serial dilution technique. The preliminary bioassay indicated that some prepared triazoles exhibited effective antibacterial and antifungal activities. Especially, 3,4-dichlorobenzyl triazolethione and its triazolium derivatives displayed the most potent activities against all the tested strains.     

Synthesis and antibacterial activity of pleuromutilin derivatives with novel C(14) side chain

In order to find novel antibacterial agents with superior antibacterial activity and overcoming multidrug resistance,a series of pleuromutilin derivatives with novel C(14) side chain were synthesized and evaluated for their in vitro antibacterial activities.The results of antibacterial acticities indicated that most of the derivatives showed potent activities against Gram-positive organisms.In particular,compound lOd exhibited the most potent inhibitory activity compared with pleuromutilin and linezoid,emerged as potential molecule for further investigation.     

Synthesis and antibacterial activity of novel [1,2,4]triazolo [3,4-h][1,8]naphthyridine-7-carboxylic acid derivatives

Novel tricyclic fluoroquinolones,[1,2,4]triazolo[3,4-h][1,8]naphthyridine-8-one-7-carboxylic acid derivatives 4a-4h bearing carrying a functional Mannich-base moiety at the C-8 position,were synthesized and evaluated for their antimicrobial activity.The results showed that some compounds with a piperazine side chain exhibited comparable or better antibacterial activity than comparator cirprofloxacin.Furthermore,the targeted compounds also displayed a broad spectrum of activity against resistant strains including both Gram-negative and Gram-positive bacteria.In particular,compound 4h showed an MIC of 0.25 μg/mL in antibacterial assay against multiple drug-resistant Escherichia coli,which represents an about 30-fold increase of potency compared to ciprofloxacin.Thus,their excellent antibacterial activity against resistant strains suggests that triazole-fused fluoroquinolones warrant further optimization as novel anti-infective chemotherapies.     

One-pot synthesis, antibacterial and antifungal activities of novel 2,5-disubstituted-1,3,4-oxadiazoles

A series of novel 2,5-disubstituted-1,3,4-oxadiazoles have been synthesized from long-chain alkanoic and alkenoic acids. The structures of these compounds have been elucidated by elemental and spectral （IR, ^1H NMR, ^13C NMR, MS） analysis. Furthermore, compounds were screened for in vitro antibacterial activity against the representative panel of two Gram-positive and two Gram- negative bacteria. All the synthesized compounds were also tested for their inhibitory action against five strains of fungus. The various compounds show potent inhibitory action against test organisms. 2007 Abdul Rauf. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.     

Study on the synthesis and antimicrobial activity of novel cationic porphyrins

A novel series of quaternary ammonium cationic derivatives based on tetrapyridyl-porphyrin was synthesized.All the compounds were evaluated for their in vitro antibacterial activities against S.aureus,E.coli and P.aeruginosa,and antifungal activities against C.albicans,where microorganisms were exposed and unexposed to the irradiation.The results revealed that some of these compounds,especially,3a and 4a displayed satisfactory antibacterial activity against Gram-positive bacteria S.aureus and moderate an...     

Synthesis and Antimicrobial Properties of the Novel Fluorinated Bis-ammonium Salts with Two Primary Amine Groups

In order to resolve the increasing resistance phenomena of the Gram-negative bacteria against single chain quaternary ammonium salts （QAS）, lysine with a pedant fluorinated bis-ammonium salts was synthesized and its antimicrobial properties were evaluated in this work. The novel fluorinated bis-ammonium salts shows similar activity with conventional single chain quaternary ammonium salts against Gram-positive bacteria but stronger activity against Gram-negative bacteria and yeast compared with the single chained counterpart.     

Theoretical study on tetranuclear boron clusters: B4X4 (X = H, F, Cl, Br, I)

The molecular orbitals for B4H4, B4F4, B4Cl4, B4Br4 and B4I4 have been calculated by using all-electron or effective core potential ab initio method at the self-consistent field level using basis sets with diffuse and polarization functions. The boron-boron and boron-halide (-hydrogen) distances of these cage compounds are optimized with three kinds of basis sets constrained to a tetrahedral symmetry. According to the localization scheme of Boys, four three-centered two-electron (3c2e) B-B-B bonds localized on each of the faces of the B4 tetrahedron are derived for B4X4 clusters. The HOMO-LUMO energy gaps, atomization energies and Mulliken overlap populations of these compounds indicate that the stabilities of the clusters decrease in the sequence of B4F4 > B4Cl4, B4H4 > B4Br4 > B4I4.     

SYNTHESIS AND CHARACTERIZATION OF SIDE CHAIN LIQUID CRYSTATALLINE POLYSILOXANES CONTAINING BENZYL ETHER LINKING UNITS

Side chain liquid crystalline polysiloxanes containing benzyl ether linkingunits were synthesized by the hydrosilylation of poly (methylhydrosiloxane) with a series of4-(4-alkoxybenzyloxy)-4'-allyloxybiphenyl monomers [4-(4-methoxybenzyloxy )-4'-allyloxy-biphenyl(M_1), 4-(4-ethoxybenzyloxy)-4'-allyloxybiphenyl (M_2), 4-(4-propoxybenzyloxy)-4'-allyloxybiphenyl (M_3), 4-(4-butoxybenzyloxy)-4'-allylox(M_4), 4-(4-pentoxy-benzyloxy)-4'-allyloxybiphenyl (M_5), 4-benzyloxy-4'-allyloxybiphenyl (M_6)]. The phasebehavior of monomeric and polymeric liquid crystals was characterized by differential scan-ning calorimetry and optical polarization microscopy where the groups are ranged frommethoxy to pentoxy Both the monomeric and polymeric liquid crystals exhibit 1iquidcrystal behaviors.     

NiTi过渡金属团簇的结构和芳香性的理论研究

在B3PW91/6-311+G(d)计算水平上, 计算并讨论了Ni₄Ti₂, [Ni₄Ti₂]²⁺, [Ni₄Ti₂]^2-与Ni₄Ti₄, [Ni₄Ti₄]²⁺, [Ni₄Ti₄]^2-团簇的几何结构和芳香性. 在构型优化过程中得到了Ni₄Ti₂(D_4h), [Ni₄Ti₂]²⁺(D_4h), [Ni₄Ti₂]^2-(D_4h)和Ni₄Ti₄(D_2h)4个稳定构型, 发现当引入上下2个Ti原子后, Ni₄环成为了平面正方形构型. 核无关化学位移(NICS)计算结果表明, Ni₄Ti₂(D_4h)与Ni₄Ti₄(D_2h)的NICS值为正, 而[Ni₄Ti₂]²⁺(D_4h)和[Ni₄Ti₂]^2-(D_4h)的NICS值为负, 且[Ni₄Ti₂]^2-(D_4h)的NICS值更负. 同时还发现, 由s与d轨道参与形成的反磁性环流是引起[Ni₄Ti₂]²⁺(D_4h)和[Ni₄Ti₂]^2-(D_4h)具有较大芳香性的主要原因; 其中Ti原子主要提供d_z²与s轨道, 而Ni原子主要利用其d_z²与d_x²-y²轨道形成正方形环, 它们之间构成了球状的d轨道环流, 且[Ni₄Ti₂]²⁺(D_4h)和[Ni₄Ti₂]^2-(D_4h)中还有非常明显的π轨道环流.     

C4Sm-4相对稳定性的从头算研究

从五十年代至今，对用通式C；；0：－…＝3，45，6n表征的氧碳化合物（OXOCCbollS）已进行了大显的理论和实验研究，认为它们是一类新的芳香化合物山．用硫、硒等取代氧的类似化合物（一般称为类氧碳化合物或假氧碳化合物，ps。11。10－OX。。CCI．b0118）的研究也有许多报导［     

Generation and collision-induced dissociation of ammonium tetrafluoroborate cluster ions

Singly and doubly charged cluster ions of ammonium tetrafluoroborate (NH4BF4) with general formula [(NH4BF4)nNH4]+ and [(NH4BF4)m(NH4)2]2+, respectively, were generated by electrospray ionization (ESI) and their fragmentation examined using collision-induced dissociation (CID) and ion-trap tandem mass spectrometry. CID of [(NH4BF4)nNH4]+ caused the loss of one or more neutral NH4BF4 units. The n = 2 cluster, [(NH4BF4)2NH4]+, was unique in that it also exhibited a dissociation pathway in which HBF4 was eliminated to create [(NH4BF4)(NH3)NH4]+. Dissociation of [(NH4BF4)m(NH4)2]2+ occurred through two general pathways: (a) 'fission' to produce singly charged cluster ions and (b) elimination of one or more neutral NH4BF4 units to leave doubly charged product ions. CID profiles, and measurements of changing precursor and product ion signal intensity as a function of applied collision voltage, were collected for [(NH4BF4)nNH4]+ and compared with those for analogous [(NaBF4)nNa]+ and [(KBF4)nK]+ ions to determine the influence of the cation on the relative stability of cluster ions. In general, the [(NH4BF4)nNH4]+ clusters were found to be easier to dissociate than both the sodium and potassium clusters of comparable size, with [(KBF4)nK]+ ions the most difficult to dissociate.     

杯芳烃钕/二正丁基镁/六甲基磷酰胺催化4-乙烯基吡啶的均聚及其与苯乙烯的共聚

聚4-乙烯基吡啶[P（4-VP）]是一种功能高分子,由于在吡啶环上有一个碱性的氮原子,它能进一步与酸反应生成各种盐,与卤代烃生成季铵盐以及与金属离子生成配合物,可用作高分子电解质,高分子试剂,高分子功能材料等,因此有不少文献对它的合成进行了报道,合成聚4-乙烯基吡啶及其与苯乙烯（St）的共聚物,除了用丁基锂作引发剂外,过渡金属的Ziegler-Natta催化剂,以及烷基铝和烷基锌等也常被用作催化剂,但用这些催化剂催化所得的聚4-乙烯基吡啶及其与苯乙烯的共聚物产率低,分子量小。     

Eight-vertex tetrametallic structures derived from cubanes: a close relationship between bisdisphenoidal metallaborane and organometallic clusters

The metallaborane Cp4Co4B4H4 and the organometallic cluster Cp4Fe4C4H4 (Cp = eta5-cyclopentadienyl) not only are isoelectronic but also exhibit completely analogous eight-vertex bisdisphenoidal structures. Such structures, as well as the tetracapped tetrahedral structure of the Cp4Fe4(mu3-CO)4 precursor to Cp4Fe4C4H4, can be derived from a cube by insertion of diagonals in each of the six faces. Furthermore, the formation of Cp4Fe4C4H4 from Cp4Fe4(mu3-CO)4 can be described as a double diamond-square-diamond process preserving D2d symmetry throughout the process.     

2-[4-取代苯基-2-氧-3-酰氨基-1-吖丁啶基]-2-苯基乙酸类化合物的合成

用叠氮钠和D-苯基甘氨酸为原料合成了2-[4-取代苯基-2-氧-3-酰氨基-1-吖啶基]-2-苯基乙酸类化合物. 在叠氮乙酰氯和亚胺化合物在三乙胺存在下在-78℃时进行环缩合反应, 可导致立体专一性合成顺-甲基-2-(4-取代苯基-2-酮-3-叠氮-1-吖啶基)-2-苯基乙酸, 催化氢化或硫化氢可减少叠氮基和得到氨基β-内酰胺后者被酰化生成α-酰氨基-β-内酰胺, 在温和碱性条件下选择性地氢化酯基既不会影响β-内酰胺环, 又不全影响酰胺侧链. 合成了二十个标题化合物, 其中九个被表明对β-内酰胺酶有抑制活性.     

Stereoselective Synthesis and Anticancer Activities of New Podophyllotoxin Derivatives:4-β-Cyano-4-Deoxy-4'-Demethylepipodophyllotoxin and 4-β-Carboxyl-4-Deoxy-4'-Demethylepipodophyllotoxin

Podophy1lotoxinl,isolatedfromPodoPhyllumpeIatumL.orPodoPhyllumemodiL.,showshighantitUmoractivity.But,itcatmotbeusedasantitUmoragentclinicallybecauseofitsseriousside-effect.Itssemisyntheticderivatives,EtoPoside2andTeniposide3,arewide-usedasboortantanticancerdrugs'.Howevef,theyhaveseverallimitationssuchaspoorwatersolubilitymetabolicinachvahonanddevelopmentofdrugresistance.Toovercometheselindtations,manyderivahvesofpodophyllotoxinhavebeensynthesizedinmanylaboratories2~5.Ithasbeenrecognisedt…     

Synthesis and α‐glucosidase inhibitory,DPPH scavenging activity of substituted 2‐oxo‐2H‐chromen‐7‐yl‐dihydrogen phosphate derivatives

Series of phosphorylated coumarin derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j ) were synthesized by Pechmann condensation, phosphorylation, and debenzylation reactions in very good yields. Thus, synthesized compounds ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j ) were evaluated for their α‐glucosidase and 1,1‐diphenyl‐2‐picrylhydrazyl scavenging activities; few compounds showed moderate to good activity. J. Heterocyclic Chem., 00 , 00 (2011).