Stability of some aryllithiums in the presence of cyano group: synthesis of biaromatic cyanoarylboronic acids and silanes

Lithium diisopropylamine (LDA)-mediated deprotonation reactions of halogenated cyanobenzyloxy-benzenes and cyanobiphenyls were investigated. The resultant organolithium derivatives were converted into the corresponding arylboronic acids or silanes. It was found that the stability of the obtained aryllithiums towards isomerization to the respective benzyllithiums depends strongly on the number of fluorine atoms in the phenyl ring and on the position of the cyano group. Halogenated cyanobiaryls were selectively deprotonated in the position flanked by two halogen atoms; however, the yield depended strongly on the reaction conditions. Addition of LDA to the cyano group was observed on the lithiation of 4-cyano-3?,5?-dichlorobiphenyl rather than deprotonation. Copyright © 2012 John Wiley & Sons, Ltd.Cyanoarylboronic acids and silanes have been obtained by lithiation of aryloxymethyl-benzonitriles or dihalogeno-cyanobiphenyls and the subsequent reaction with B(OR)3 or Me3SiCl. The stability of the obtained cyano-aryllithiums depends on the position of the cyano group and the number of fluorine atoms in the phenyl ring

Posted on 9 May 2012 | 10:58 am

Microwave-promoted piperidination of halopyridines: a comparison between Ullmann, Buchwald–Hartwig and uncatalysed SNAr reactions

A comparative study between the most used methodologies for the preparation of piperidinyl pyridines (Buchwald–Hartwig reaction, Ullmann reaction and nucleophilic aromatic substitution (SNAr)) by microwave-assisted piperidination of halopyridines is reported. Our results suggest that the Ullmann reaction is most effective for less reactive halopyridines, while uncatalysed SNAr is sufficient for more reactive ones. Copyright © 2012 John Wiley & Sons, Ltd.Microwave piperidination of halopyridines: a comparison between Ullmann, Buchwald-Hartwig and uncatalysed SNAr reactions.

Posted on 9 May 2012 | 10:58 am

Synthesis of a layered crystalline AlSPP and reusable catalysts for epoxidation of unfunctionalized olefins

A type of organic–inorganic hybrid material layered crystalline AlSPP (AlSPP) was prepared under simple conditions, completely different to the traditional hydrothermal methods, by the reaction of oligo-styrenyl phosphonic acid with aluminum acetate and sodium dihydrogen phosphate. The microstructure of AlSPP was characterized by X-ray diffraction, FT-IR, atomic absorption spectroscopy, N2 volumetric adsorption, atomic force microscopy, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. Based on the experimental date, the ideal structure model of AlSPP is proposed, which indicated that the layered crystalline AlSPP samples are special lamellar structure with many cavums, holes, channels and ravines on the surface, the interlamellar region and interlayer surfaces of the particles. Therefore AlSPP possesses excellent properties and has potential applications for heterogeneous asymmetric catalyst supports. Copyright © 2012 John Wiley & Sons, Ltd.(a) The two or more neighboring -PO3H2 groups (there is a oligo-styrenyl chain between and connected them) are in same colloidal precipitation; (b) The two neighboring -PO3H2 groups (there is a oligo-styrenyl segment between and linked them) are in different colloidal precipitation. In the aggregation process of the colloidal precipitation into bigger particles, many precipitation particles link each other to form even bigger hybrid AlSPP precipitation particles, a great deal of channels, holes and cavums with different volume and shapes are gradually formed. Therefore, if precipitation particles link in the form of model b, different length and shape of channels, holes and cavums will come into being. And if the particles link in the form of model a, the channels, holes and cavums with smaller volume will be formed and cover on the surface of the small precipitation particles.

Posted on 9 May 2012 | 10:51 am

ZnI2-promoted homologation of ferrocenylacetylene and aldehydes: an efficient synthesis of ferrocene-containing allenes

A concise and efficient protocol for the first synthesis of ferrocene-containing allenes based on the homologation reaction of ferrocenylacetylene and aldehydes promoted by ZnI2 was developed. The present method was applicable to many kinds of substituted aldehydes, providing good to excellent yields of ferrocene-containing allenes. Copyright © 2012 John Wiley & Sons, Ltd.A concise and efficient protocol for the first synthesis of ferrocene-containing allenes based on the homologation reaction of ferrocenylacetylene and aldehydes promoted by ZnI2 was developed. The present method was applicable to many kinds of substituted aldehydes providing good to excellent yields of ferrocene-containing allenes.

Posted on 9 May 2012 | 10:50 am

The influence of some triphenylantimony(V) catecholates and o-amidophenolates on lipid peroxidation in vitro

A number of catecholates (complexes 1–3, 6) and o-amidophenolates (complexes 4, 5) of triphenylantimony(V) was examined in the process of lipid peroxidation of liver homogenates and sperm of Russian sturgeon (Acipenser gueldenstaedti B.), and human red blood cells. It was shown that the influence of complexes 1–6 on lipid peroxidation process in model systems depends on the nature of redox-active ligand and varies from weak anti- and pro-oxidant (catecholates 1, 6) to pronounced antioxidant (catecholates and o-amidophenolates 2–5). It was found that the complexes 2–5 are the more effective inhibitors of lipid peroxidation than standard antioxidant ionol. Copyright © 2012 John Wiley & Sons, Ltd.The activity of triphenylantimony(V) catecholates (complexes 1-3, 6) and o-amidophenolates (complexes 4, 5) in the LP of model systems (liver homogenates and sperm of Russian sturgeon (Acipenser gueldenstaedti B.), and human red blood cells) depends on the nature of redox-active ligand, type of model system and varies from weak anti- and prooxidant (1, 6) to pronounced antioxidant (2-5). The antioxidant activity of complexes from the second group exceeds the activity of ionol and has a pronounced effect in time.

Posted on 9 May 2012 | 10:50 am

EDITED BY ARMANDO CÓRDOVA Catalytic Asymmetric Conjugate Reactions Wiley-VCH, 2010, 464 pp. Price £115.00 / €138.00 (hardcover) ISBN-978-3-527-32411-8

Posted on 8 May 2012 | 1:25 pm

EDITED BY LEONARD R. MACGILLIVRAY Metal-Organic Frameworks: Design and Application Wiley, 2010, 368 pp. Price £83.50 / €100.20 (hardcover) ISBN-978-0-470-19556-7

Posted on 8 May 2012 | 1:25 pm

Metal organic chemical vapor deposition of ZnO from ?-ketoiminates

ZnO is a high-mobility electron conductor being considered for high-throughput electronics in flexible and transparent formats. We demonstrated the Zn ?-ketoiminate system, based on acetylacetimine with N-propyl, isopropyl, and butyl groups, as a vehicle for preparing ZnO thin films for electronic applications. Surface carbon was a primary impurity, and the precursors studied afforded films with the lowest surface carbon contamination at deposition temperatures near 400°C. Thermal annealing of the films reduced the surface carbon content and afforded semiconducting materials. Annealing also gave larger-grained, better connected films. Thinner films were associated with semiconducting as opposed to ohmic behavior; such films will be adaptable for transparent logic circuits. Copyright © 2012 John Wiley & Sons, Ltd.We demonstrated the Zn ?-ketoiminate system, based on acetylacetimine with N-propyl, isopropyl, and butyl groups, as a vehicle for preparing Zno thin films for electronic applications. Thermal annealing of the films reduced the surface carbon content and afforded semiconducting materials.

Posted on 27 April 2012 | 12:23 pm

Cyclopalladated ferrocenylimine as an efficient catalyst for the syntheses of diarylmethane derivatives

The cyclopalladated ferrocenylimine adducts Ia–c were evaluated in the Suzuki cross-coupling reaction of benzyl halides with arylboronic acids. The tricyclohexylphosphine adduct Ia exhibited highly catalytic activity for the coupling of aryl and heteroaryl boronic acids containing various functional groups with benzylic bromides and chlorides (up to 99% yield), furnishing diarylmethane derivatives with low catalyst loading (1?mol%). It is worth noting that catalyst Ia can be reused eight times without losing its catalytic activity. Copyright © 2012 John Wiley & Sons, Ltd.The cyclopalladated ferrocenylimine adducts Ia-c were evaluated in the Suzuki cross-coupling reaction of benzyl halides with arylboronic acids. The tricyclohexylphosphine adduct Ia exhibited highly catalytic activity for the coupling of aryl and heteroaryl boronic acids containing various functional groups with benzylic bromides and chlorides (up to 99% yield) furnishing diarylmethane derivatives with low catalyst loading (1?mol %). It is noting that catalyst Ia can be reused for eight times without losing its catalytic activity.

Posted on 25 April 2012 | 8:46 am

EDITED BY BRUNO PIGNATARO Ideas in Chemistry and Molecular Sciences: Where Chemistry Meets Life Wiley-VCH, 2010, 358 Price £85.00 / €102.00 (hardcover) ISBN -978-3-527-32541-2

Posted on 17 April 2012 | 5:45 am

Synthesis and cytostatic activity of Pt(II) complexes of intramolecularly coordinated phosphine and stibine ligands

The intramolecularly coordinated phosphine and stibine ligands L1PPh2 (1), L2PPh2 (2) and L2SbPh2 (3) containing Y,C,Y-chelating ligands, L1?=?2,6-(tBuOCH2)2C6H4? and L2?=?2,6-(Me2NCH2)2C6H4?, were prepared and characterized. The treatment of these ligands 1–3 with PtCl2 yielded complexes trans-{[2,6-(tBuOCH2)2C6H3]PPh2}2PtCl2 (4), cis-{[2,6-(Me2NCH2)2C6H3]PPh2}PtCl2 (5), and cis-{[2,6-(Me2NCH2)2C6H3]SbPh2}PtCl2 (6) as the result of different ability of the starting compounds 1–3 to complex platinum centre. Compounds 1–6 were characterized by 1H, 13C and 31P NMR spectroscopy and electrospray ionization mass spectrometry, and molecular structures of 3–6 were determined by X-ray diffraction analysis. The substitution reactions of complexes 4–6 were also studied. The reaction of 5 and 6 with NaI yielded complexes {[2,6-(Me2NCH2)2C6H3]PPh2}PtI2 (7) and {[2,6-(Me2NCH2)2C6H3]SbPh2}PtI2 (8), while the same reaction of 4 with NaI did not proceed. As the compounds 7 and 8 structurally resemble cisplatin, complex {{[2-(Me2NCH2)-6-(Me2NHCH2)C6H3]PPh2}PtCl2}+Cl? (9) was prepared as water-soluble platinum complex. The cytotoxic effect of complex 9 was evaluated on human T-lymphocytic leukemia cells MOLT-4 (IC50?=?27.6?±?1.8 µmol l?1) and human promyelocytic leukemia HL-60 (IC50?=?55.9?±?4.9 µmol l?1). Copyright © 2012 John Wiley & Sons, Ltd.An intramolecularly coordinated phosphine and stibine ligands L1PPh2 (1), L2PPh2 (2) L2SbPh2 (3) containing Y,C,Y-chelating ligands, L1 = 2,6-(tBuOCH2)2C6H4- and L2 = 2,6-(Me2NCH2)2C6H4-, were treated with PtCl2 to give complexes trans-{[2,6-(tBuOCH2)2C6H3]PPh2}2PtCl2 (4), cis-{[2,6-(Me2NCH2)2C6H3]PPh2}PtCl2 (5), and cis-{[2,6-(Me2NCH2)2C6H3]SbPh2}PtCl2 (6). Complex {{[2-(Me2NCH2)-6-(Me2NHCH2)C6H3]PPh2}PtCl2}+Cl- (9) was also prepared as a water soluble platinum complex. Cytotoxic effect of complex 9 was evaluated on human T-lymphocytic leukemia cells MOLT?-?4 (IC50 = 27.6 ± 1.8 µmol/L) and human promyelocytic leukemia HL?-?60 (IC50 = 55.9 ± 4.9 µmol/L).

Posted on 13 April 2012 | 11:26 am

Epoxidation of styrene with molecular oxygen catalyzed by a novel oxovanadium(IV) catalyst containing two different kinds of ligands

A novel type of oxovanadium(IV) 8-hydroxyquinoline (8-Q) complex and oxovanadium(IV) acetylacetonate (acac) complex were synchronously anchored on to amino-modified SBA-15 (named VO(acac:8-Q)-SBA-15) and examined as a catalyst for styrene oxidation. The structure of the synthesized catalyst was characterized by means of X-ray diffraction (XRD), FT-IR, diffusion reflection UV–visible, inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). Characterizations with FT-IR, diffusion reflection UV-visible, ICP-AES and TG suggested the incorporation of oxovanadium(IV) complex in amino-modified SBA-15. XRD and SEM results indicated that SBA-15 remained intact throughout the grafting procedure. It was found that VO(acac:8-Q)-SBA-15 catalyst was more active than single-ligand catalysts VO(acac)2-SBA-15 and VO(8-Q)2-SBA-15 and that the product selectivity varied in cases of different oxidants. The catalyst VO(acac:8-Q)-SBA-15 with two different ligands showed high yield of styrene oxide (45.8%) and good recoverability when using air as oxidant. Copyright © 2012 John Wiley & Sons, Ltd.A novel oxovanadium(IV) catalyst (VO(acac:8-Q)-SBA-15) simultaneously containing 8-Hydroxyquinoline (8-Q) and acetylacetonate (acac) ligands has been successfully prepared. The catalyst showed high yield of styrene oxide (45.8%) and good recoverability for the epoxidation of styrene.

Posted on 13 April 2012 | 11:15 am

Synthesis, spectral investigation and biological interphase of drug-based cytotoxic square pyramidal coordination compounds

We have synthesized ciprofloxacin-based metal complexes of bipyridine derivatives [Cu(CFL)(An)Cl].2H2O (where CFL?=?ciprofloxacin and A?=?bipyridines e.g. A1?=?4-(4-fluorophenyl)-6-p-tolyl-2,2?-bipyridine, A6?=?4-(4-(benzyloxy)phenyl)-6-(4-bromophenyl)-2,2?-bipyridine, etc.). The ligands and complexes were characterized using analytical (C, H, N elemental analysis, TGA and magnetic measurement) and spectroscopic methods (1H and 13C NMR, FT-IR, fast atom bombardment mass and reflectance spectroscopy). The products were evaluated by screening for DNA interaction activity on herring sperm DNA and studies suggest intercalative mode of DNA binding. The antimicrobial activity was determined in terms of minimum inhibitory concentration. Superoxide dismutase mimic studies were performed using the NADH/PMS/NBT system. The brine shrimp bioassay was also carried out to study the in vitro cytotoxic properties of the synthesized metal complexes. Copyright © 2012 John Wiley & Sons, Ltd.Square pyramidal copper(II) complexes have been synthesized using ciprofloxacin and bipyridines. Their cytotoxic, antibacterial, DNA interaction and SOD mimic activity have also been evaluated.

Posted on 12 April 2012 | 10:53 am

Symmetric and dissymmetric N-heterocyclic carbene rhodium(I) complexes: a comparative study of their catalytic activities in transfer hydrogenation reaction

Six new [RhBr(NHC)(cod)] (NHC?=?N-heterocyclic carbene; cod?=?1,5-cyclooctadiene) type rhodium complexes (4–6) have been prepared by the reaction of [Rh(?-OMe)(cod)]2 with a series of corresponding imidazoli(in)ium bromides (1–3) bearing mesityl (Mes) or 2,4,6-trimethylbenzyl (CH2Mes) substituents at N1 and N3 positions. They have been fully characterized by 1?H, 13?C and heteronuclear multiple quantum correlation NMR analyses, elemental analysis and mass spectroscopy. Complexes of type [(NHC)RhBr(CO)2] (NHC?=?imidazol-2-ylidene) (7b–9b) were also synthesized to compare ?-donor/?-acceptor strength of NHC ligands. Transfer hydrogenation (TH) reaction of acetophenone has been comparatively studied by using complexes 4–6 as catalysts. The symmetrically CH2Mes-substituted rhodium complex bearing a saturated NHC ligand (5a) showed the highest catalytic activity for TH reaction. Copyright © 2012 John Wiley & Sons, Ltd.Six new [RhBr(NHC)(cod)] type rhodium complexes have been prepared and characterized. Transfer hydrogenation (TH) reaction of acetophenone has been comparatively studied by using these complexes as catalysts to compare the effect of substituted aryl and benzyl groups to nitrogen atom of the imidazol(in)-2-ylidene.

Posted on 12 April 2012 | 10:44 am

Synthesis, characterization and anticancer studies of ferrocenyl complexes containing thiazole moiety

A ferrocenyl ligand was prepared from condensation of l,l?-diacetylferrocene with 2-amino-5-methylthiazole, to give the ligand. This ligand forms 1:1 complexes with lead(II), cobalt(II), nickel(II), copper(II) and zinc(II) in good yield. Characterization of the ligand and complexes was carried out using IR, NMR, electronic absorption, magnetic susceptibility, molar conductivity and elemental analysis. Anticancer activity of the prepared ligand and its complexes against breast cancer cell line MCF-7 was determined. The anticancer activity of the new complexes was accompanied by significant increase in the activity of superoxide dismutase, with a parallel decrease in the activities of catalase and glutathione peroxidase and reduced glutathione level. Accordingly, the overproduction of free radicals allowed reactive oxygen species-mediated cancer cell death. The results suggest that the complexes possess significant anticancer activity comparable to cisplatin. Copyright © 2012 John Wiley & Sons, Ltd.A ferrocenyl ligand was prepared and exploited to prepare complexes with some transition metals. Anticancer activity against breast cancer cell line MCF-7 was determined and compared with cisplatin.

Posted on 12 April 2012 | 9:57 am

Synthesis, physicochemical characterization and biological activity of nano complexes of iron(III) of 3(2'-hydroxyphenyl)-5-(4?-substituted phenyl) pyrazolines and aspartic acid

Mixed ligand complexes of Iron(III) with aspartic acid and 3(2?-hydroxy phenyl)-5-(4?-substituted phenyl) pyrazolines of type [Fe(C4O4NH6)2(C15H12N2OX)] and [Fe(C4O4NH6)(C15H12N2OX)2], where (C4O4NH6)?=?aspartate, (C15H12N2OX)?=?deprotonated 3(2?-hydroxyphenyl)-5-(4?-substituted phenyl) pyrazolines (X?=?H, CH3, OCH3, Cl), have been synthesized. These newly synthesized derivatives have been physicochemically characterized by elemental analysis (C, H, N, Cl and Fe), magnetic moment data, thermogravimetric analysis, molar conductance, cyclic voltammetry, spectral analysis (UV–visible, IR, far IR and fast atom bombardment mass spectrometry). Scanning electron microscopy, transmission electron microscopy and X-ray powder diffraction studies have been carried out for powdered samples, which show nanometric particles of these derivatives. Antibacterial and antifungal potential of free pyrazoline and some iron(III) complexes have been evaluated. Copyright © 2012 John Wiley & Sons, Ltd.Mixed ligand complexes of iron(III) with aspartic acid and 3(2’-hydroxy phenyl)-5-(4’-substituted phenyl) pyrazolines have been synthesized and physico-chemically characterized. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) studies have been carried out for powdered sample, which show nanometric particles for these derivatives. Antimicrobial activity shows that these complexes can be used as precursor of nano antibiotic and nano antifungal drug.

Posted on 11 April 2012 | 12:45 pm

An efficient solid-phase synthesis of substituted benzofuran using selenium-bound resin

A very efficient solid-phase synthesis of substituted benzofuran using polymer-supported selenium resin is described. The advantages of the new method are good yields, high purity, straightforward operations, broad range and high diversity of products, lack of odor, and good stability of the resins. The easy work-up procedure makes the method suitable for building parallel libraries. Copyright © 2012 John Wiley & Sons, Ltd.A library of substituted benzofuran has been synthesized using polymer-supported selenium resin. The advantages of the solid-phase synthesis method are good yields, high purity, straightforward operations, broad range and high diversity of the products, lack of odor, and good stability of the resins.

Posted on 10 April 2012 | 10:45 am

Copolymerization of styrene and norbornene with ?-diketiminato nickel/methylaluminoxane catalytic system

Styrene–norbornene (S-N) copolymerizations were carried out using ?-diketiminato nickel complexes CH{C(CF3)NAr}2NiBr (Ar?=?2,6-iPr2C6H3, 1; Ar?=?2,6-Me2C6H3, 2) in the presence of methylaluminoxane. The influence of the comonomer feed content and polymerization temperature on the conversion and composition of the copolymers with the catalytic system was investigated. An increase in the feed ratio of S/N led to an increase in the incorporated styrene content of the resulting copolymer. NMR characterization of the copolymers generated with the catalytic systems showed that the random S-N copolymers are produced. Differential scanning calorimetric determination of the copolymers shows higher Tg values than polystyrene, and gel permeation chromatographic measurements have shown that the copolymers possess rather narrow molecular weight distributions, suggesting that the copolymerization take place at a single active site. Copyright © 2012 John Wiley & Sons, Ltd.?-Diketiminato nickel complexes were studied for catalytic polymerization of styrene and norbornene in the presence of MAO. An increase in the feed ratio of styrene/norbornene (S/N) led to an increase in the incorporated styrene content of the resulting copolymer. Structure characterization of the copolymers generated with the catalytic systems showed that the random styrene-norbornene copolymers are produced.

Posted on 10 April 2012 | 10:43 am