The synthesis of (±) cis-trikentrin a

The synthesis of a novel sponge metabolite is described, utilising an aryl radical cyclisation to form the substituted indane system.     

Synthesis and Crystal Structure of a New Dinuclear Manganese(Ⅱ) Manganese(Ⅲ) Complex of a Macrocyclic Ligand

A mixed-valence dinuclear manganese complex, [MnⅡMnⅢL](ClO4)·1/2MeOH, where L is a macrocyclic ligand derived from the cyclocondensation of sodium 2,6-diformyl-4-methylphenolate with N,N-bis(2-aminoethyl)-2-hydroxybenzyl amine, was obtained and its structure was determined by X-ray diffraction. The orange crystal is a monoclinic system with space group P21/c and lattice parameters a=1.1617(4), b=1.4005(3), c=1.4641(3) nm, β=113.03(2)°, and Z=2. The crystal structure shows that each pendant-arm is bonded in a bidentate fashion to the adjacent metal atom and that both the arms are on the same side of the macrocycle. The two Mn atoms are bridged by two μ2-phenoxy oxygen atoms of the tetra-imine macrocycle, and each Mn atom, locating in a trigonal prismatic coordination environment(N3O3), is six-coordinated by the two imine nitrogen atoms, one tertiary nitrogen atom and a pendant phenol moiety apart from the two oxygen atoms.     

Synthesis of a C(9)—C(13) fragment of acutiphycin from levoglucosan

Alkylation of (1R,2R,5R)-2-benzenesulfonyl-6,8-dioxa-bicyclo[3.2.1]octan-3-one, which is accessible from levoglucosan, afforded (1R,2R,5R)-2-benzenesylfonyl-2,4,4-trimethyl-6,8-dioxabicyclo[3.2.1]octan-3-one. This was further converted into (1S,2R,3S,5R)-2,4,4-trimethyl-6,8-dioxabicyclo[3.2.1]octan-3-ol representing the C9—C13 fragment of acutiphycin molecule.     

Chemo-Enzymic Synthesis of a Four-Chiral-Center Portion of A-23187(Calcimycin)

A-23l87(calcimycin)[']wasisolatedfromthecultUresofstrePtomyceschartreusensiS.Itisauniquedivalentcati0nionphoreandcharacteristicallyfrOmslipophilicmetalioncomplexeswhichareeffectiveiniontransportacrosslipidbhoer.TillnowhundredsofpaPersareaccumulatingontheaPplicationofthisionphoreasaneffectivepr0befortheinvolvementofmetalionsinthecontrol0fnumerousPhysiologicalprocesses.BesidesitSspecificbiologicalfunctionsitalsohasauniquestrUctUretoattractmuchattentionofsyntheticchemist.lthassevenchiralcente…     

Development of a N-acetyl-β-D-glucosaminidase (NAG) assay on a centrifugal lab-on-a-compact-disc (Lab-CD) platform

A centrifugal microfluidic platform, which is also known as lab-on-a-compact-disc (Lab-CD), was developed for use as a urinary N-acetyl-β-D-glucosaminidase (NAG) activity assay. In this work, Lab-CD design, centrifugal operations and analytical procedures were established. Automated liquid handling on Lab-CD processes, such as fluid transport, sample metering, mixing, and fluorescence detection are accomplished using a portable Lab-CD system. The linearity of the NAG assay using 4-methylumbelliferyl-N-acetyl-β-D-glucosaminide (4-MU-GlcNAc) was found to be acceptable in the range of 2.5 to 20 U L(-1); the relative standard deviations for the fluorescence intensity of eight samples (7.5 U L(-1)) was 6.4%. Clinical diagnostics is one of the most promising applications for Lab-CD technologies. All the benefits of miniaturization, such as reduced sample requirement, reduced reagent consumption and automation, are realized in this investigation.     

A short total synthesis of (±)-epimeloscine and (±)-meloscine enabled by a cascade radical annulation of a divinylcyclopropane

The first stereoselective synthesis of epimeloscine has been accomplished in 13 total steps with a longest linear sequence of 10 steps. The core of the synthesis takes only five steps, the key ones being acylation, stereoselective tandem radical cyclization of a divinylcyclopropane to make two rings, and group-selective ring-closing metathesis of the resulting divinylcyclopentane to make the last ring.     

Synthesis of a ball-chain system C_(60) aza-derivative

Nitrenes generated by thermolysis of alkyl azides were found to add to C60 in chloroben-zene solvent. The product was isolated by means of silica gel chromatography and identified by field desorption mass spectroscopy and 13C NMR spectroscopy.     

Solid-state electrochemiluminescence of a novel iridium(Ⅲ) complex

The sofid-state ECL behavior of a water-insoluble bis-cyclometalated (pq)2Ir(N-phMA) complex is presented, in which pq is a 2-phenylquinoline anion and N-phMA is N-phenyl methacrylamide, a monoanionic bidentate ligand. The MWNTs/(pq)2Ir(N-phMA) film, MWNTs/Ru(bpy)32+ film and (pq)2Ir(N-phMA) directly modified glassy carbon electrode were fabricated; only the MWNTs/(pq)2Ir(N-phMA) film can produce steady ECL in the presence of tri-n-propylamine as a coreactant.     

Application of Mn(Ⅱ) as a Mimetic Enzyme of Horseradish Peroxidase

HRP is a most commonly used enzyme in H2O2 and glucose detection1, owing to its 2strong activity and quite good selectivity. However, natural HRP has manyshortcomings, such as its expensiveness and instability; the experimental conditions andstorage environment are inconvenient. Therefore, the search for a replacement3-6 forHRP has become an important and interesting work. This paper describes a catalytic spectrophotometry method for the determination ofH2O2 based on …     

Synthesis and Conductivity of a One-dimensional Polymer of a Copper(Ⅱ)-porphyrazine with Sulfur Bridges

Phthalocyanines(Pcs)andtheirpolyinershavebeenasubjectofgreatinterestduetotheirhighthermalstabilityanduniquephotoelectricpropertiesl4.Ithasbeenfoundthatsomeelectronicfunctionsofthemetalthioporphyrazinesandtheirconjugatedpolymers,suchasgas-sensitivityphotosensitivity,photoconductivityandelectrocatalyticactivity,aremorepeculiarthancorrespondingPcs5'6.Oneofourinterestsistodesignanovelpolymerofmetalporphyrazines(PMPzs)withswitchingpointsunderthecontrolofachangingexternalfieIdorenvironment.Inthepr…     

On a novel tentative stereochemical microstructure based explanation of β relaxation of poly(vinylchloride) (PVC)

A set of PVC samples with various stereochemical microstructures, especially the mmmr and the mmmmrx (x = m or r placement) repeating stereosequences, termini of isotactic sequences, has been prepared whether by changing the temperature of polymerization or by S_N2 substitution reaction which was demonstrated to occur through a highly stereospecific mechanism. The stereochemical microstructures were accurately analysed by ¹³C NMR spectroscopy. For purposes of stating the microstructure/β relaxation relationship, the mechanical behaviour of all samples was studied by a dynamic mechanical thermal analyser (DMTA). The results are discussed on the ground of earlier fundamental contributions within the framework of the property/stereochemical microstructure relationships as abundantly studied in our laboratory. Basically it is shown that β relaxation decreases in both temperature and intensity with the content of the aforementioned microstructures, thereby suggesting that relaxation to stem from the enhanced free volume and favoured rotational motion facilities of the mmmr pentad under GTGTTG⁻TT conformation.     

Efficient Synthesis of a New Series of Piperidine Ring-Modified Analogs of (±)-threo-Methyl Phenyl(piperidin-2-yl)acetate

A series of novel piperidine ring modified analogs of (±)-threo-methyl phenyl(piperidin-2-yl)acetate was synthesized by direct alkylation and reductive amination procedure, using sodium borohydride over molecular sieves. The chemical structures of these compounds were established based on mass spectra, ¹H NMR spectra, and CHN elemental analysis data. Several significant modifications in the literature methodologies were made to make the reaction more efficient, and good yields were generally obtained.     

Off-on-off Luminescent Switching of a Novel Ru(II) Complex

There has been explosive interest in the synthesis and applications of novel Ru(II) polypyridyl complexes with respect to molecular sensors1,2, switches3, and sensitizers of Gr鋞zel solar cells based on nanocrystalline TiO24. Here we report a novel Ru(II) complex, which can serve as pH-induced remarkable off-on-off luminescent switch. Scheme 1 The acid-base equilibria of the complex UV-vis absorption and emission spectroscopic pH titration experiments of the Ru complex wit…     

Synthesis of (±)-ircinianin,a marine sponge sesterterpene

A biogenetic-type synthesis of (±)-ircinianin (1) via intramolecular Diels-Alder reaction of 2 is described.     

Synthesis and Electrochemical Properties of a New Tetraazamacrocyclic Complex of Silver (Ⅰ)

Themetalmacrocycliccomplexeswiththeirunusualoxidationstateshaveattractedmuchinterest.Silver(Il)andsi1ver(IlI)compoundsareusuallyunstab1eduetotheirstrongoxidation.Butsometetraazamacrocyclicligandscandirectlygivestablecom-plexesofsiIver(Il)throughdisproportionatedreactionofsilver(I).12fIere,wereportthesynthesisandeIectrochemicalbehaviorofanewsilver(Il)com-plexAgL(CIO')2(L=5,7,l2,l4-tetraethyl-5,l2-dimethyl-l,4,8,ll-tetraazacyclotetradec-4,l1-diene).Therelativeinformationaboutothersilver(1I…     

Synthesis,structure and magnetism of a hydrogen-bond-linked three-dimensional network of a novel nickel(II)–cobalt(II)–nickel(II) complex containing a new macrocyclic mononuclear complex ligand

A novel trinuclear complex, [Co(NiL)₂(H₂O)₂](ClO₄)₂ · 2C₂H₅OH, was prepared by self-assembly using [NiL] as a new complex ligand; L is the dianion of dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. The structure of the trinuclear complex was determined by X-ray crystallography. The Co^II ion is at the center of the trinuclear complex cation and occupies a distorted octahedral O₆ environment, approximating to O _h with a ⁴ T _1g ground state for Co^II that has an unquenched spin–orbit coupling reflected in the magnetic properties. Two Ni^II ions reside in completely same and slightly distorted square-planar N₄ coordination geometries. Co^II and each Ni^II are bridged by an oxamido group from one of the two macrocyclic ligands (L). O—H...O and ... interactions link the trinuclear fragments, perchlorate ions and C₂H₅OH molecules to form a three-dimensional supramolecular architecture.     

Synthesis of alkyl (α-phenylthioalkenyl) ketones containing a (Z)-trisubstituted olefinic fragment

Warren"s method, which has been proposed for the synthesis of -phenylthiodialkyl ketones, appeared to be inefficient for the preparation of their alkenyl alkyl analogs. The latter were prepared in good yields by alkenylation of alkyl phenylthiomethyl ketones with alkenyl bromides.     

Synthesis of a new complex Chromium (Ⅲ) 2-mercaptonicotinate

Chromium is an essential trace element for mammals[1-3].Diabetes is a chronic disease with major health consequence.Studies show that the occurrence of diabetes have great thing to do with the chromium deficient。Almost 40 years after the first report of glucose tolerance factor(GTF) [4] no conclusive evidence for an isolable ,biologically active form of chromium exited。Three materials have been proposed to be the biologically active form of chromium:“glucose tolerance factor”,chromium Pi…     

Electrogeneration and characterization of a poly(pyrrole–nickel (II) chlorin) electrode

We describe herein, the electrochemical properties of an hydroporphyrin of Ni(II) substituted by two pyrrole groups in organic media (THF and CH₂Cl₂). In the anodic region it has been shown that the electrochemical behaviour of this complex investigated by cyclic voltammetry and coulometry coupled with UV–visible spectroscopy is strongly dependent on the nature of the solvent.Furthermore, the electrochemical oxidation of the pyrrrole groups has led to the first example of an electrogenerated polypyrrole–metallochlorin film. The resulting modified electrodes exhibit the same electrochemical properties as the monomer free in solution. Preliminary experiments have also demonstrated the possibility to study electrochemically this polymeric film in CH₃CN contrary to the Ni(II) chlorin, which is insoluble in this medium.