bluuebunny/crossref_metadata_2025 huggingface dataset:
μ‐1,3‐ (trans) and μ‐1,2‐ (cis) Bonding in Squarato‐Bridged Dinuclear Copper(II) and Nickel(II) Complexes Derived from Polypyridyl Amines
Authors: Massoud Salah S. , Mautner Franz A. , Vicente Ramon , Louka Febee R.
Published: July 2008

A novel series of dinuclear squarato‐bridged copper(II) and nickel(II) complexes [Cu2(TPA)2(μ1,3‐C4O4)](ClO4)2·4H2O (1), [Cu2(MeDPA)2(μ1,3‐C4O4)(H2O)4](ClO4)2 (2) and [Ni2(TPA)2(μ1,2‐C4O4)(H2O)2](ClO4)2 (3) [C4O42– = dianion of 3,4‐dihydroxycyclobut‐3‐en‐1,2‐dione (squaric acid), MeDPA = N‐methylbis(2‐pyridylmethyl)amine, TPA = tris(2‐pyridylmethyl)amine] were synthesized and structurally characterized by X‐ray crystallography. The spectral and structural characterizations as well as their magnetic properties are reported. In this series, the structures consist of the ClO4– groups as counterions and the C4O42– anions bridging the two MII centers in a μ‐1,3‐ (1 and 2) or in a μ‐1,2‐bis(monodentate) (3) bonding fashion. The coordination geometry around the five‐coordinate CuII centers in 1 is a distorted trigonal bipyramid, where the coordination environment is achieved by the four N‐donor atoms of the TPA ligand and one oxygen atom of the bridging squarato ligand. The complexes 2 and 3 adopt a distorted octahedral geometry. The six‐coordinate 4+2 environment in 2 is achieved by the three N‐atoms of the MeDPA ligand, by an oxygen atom of a bridging squarato ligand and, at longest distances, by two oxygen atoms from coordinated water molecules. In the nickel complex 3, the geometry is attained by the four N‐atoms of TPA and by two oxygen atoms supplied by a coordinated water molecule and by a bridging squarato ligand. The results manifested the effects of the blocking amine variations on the structure and on the bonding mode of the bridging squarato ligand. The complexes show antiferromagnetic coupling with |J| = 9.1 and 1.2 cm–1 in the μ‐1,3‐bridged squarato compounds 1 and 2, and with J = –1.4 cm–1 in the corresponding μ‐1,2‐bridged squarato complex 3. The magnetic properties are discussed in relation to other related compounds and the structural data.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Functionalization of Gold Nanoparticles by Iron(III) Complexes Derived from Schiff Base Ligands
Authors: Mayer Cédric R. , Cucchiaro Gregory , Jullien Josseline , Dumur Frédéric , Marrot Jérôme , Dumas Eddy , Sécheresse Francis
Published: July 2008

A series of iron(III) complexes derived from a variety of pentadentate Schiff base ligands, namely salten [H2salten = bis(3‐salicylideneaminopropyl)amine] derivatives, have been synthesized and further used to stabilize and functionalize gold nanoparticles (Au‐NPs). The iron complexes have been specifically designed to interact with the Au‐NPs through an ambidentate thiocyanate ligand or through a pendant thiol group carried by the salten derivative ligand. The gold nanocomposites have been synthesized either by direct reduction of AuIII in the presence of iron complexes or by coordination chemistry on prefunctionalized gold nanoparticles; in the latter case Au‐NPs bearing pendant empty salten cages have been treated with FeIII to generate the iron complexes. Steric and electrostatic repulsions have been tuned to obtain stable colloidal solutions or to induce the precipitation of the gold nanocomposites. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
On the Role of Tyrosine as Catalytic Base in Nitrile Hydratase
Authors: Hopmann Kathrin H. , Himo Fahmi
Published: July 2008

Nitrile Hydratases (NHases) catalyze the conversion of nitriles to their corresponding amides. Two NHase classes exist, the FeIII‐NHases and the CoIII‐NHases. Both harbour an intriguing active site, with a low‐spin metal ion coordinated to deprotonated back‐bone amides and oxidized cysteine residues. So far it has not been possible to conclusively determine the reaction mechanism of NHase. Here we employ density functional theory to investigate the recent proposal that a fully conserved second‐shell tyrosine residue is the catalytic base of nitrile hydratase (J. Biol. Chem. 2007, 282, 7397–7404). In the proposed mechanism, the tyrosine is suggested to be in the tyrosinate state and to mediate nitrile hydration through activation of a water molecule, which attacks the metal‐bound substrate. We have explored this mechanism employing quantum chemical active site models on the basis of the CoIII‐NHase from P. thermophila JCM 3095 and the FeIII‐NHase from R. erythropolis N‐771. Potential energy curves and optimized transition states are presented. The computed barriers for the two models are a few kcal/mol above the experimental value, indicating that the conserved second‐shell tyrosine could function as the catalytic base of NHase. To further evaluate the likelihood of this mechanism, we estimated the pKa value of the second‐shell tyrosine in each model. We also provide estimates of the energy involved in the exchange of a metal‐bound water molecule with a nitrile substrate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
The Reaction of N,N′‐Di‐tert‐butylthiourea (dtbtu) with Antimony(III) Halides – Formation of the Triply Bridged [(dtbtu)SbX2(μ‐X)2(μ‐dtbtu)SbX2(dtbtu)] (X = Cl, Br) Dimers
Authors: Barnes Nicholas A. , Godfrey Stephen M. , Pritchard Robin G. , Ratcliffe Shane
Published: July 2008

The reactions of N,N′‐di‐tert‐butylthiourea (dtbtu) with SbX3 (X = Cl, Br) in a 2:1 dtbtu/SbX3 ratio unexpectedly lead to products with a 3:2 dtbtu/SbX3 ratio. These complexes have been shown by X‐ray crystallographic studies to exist as triply bridged dimers, [(dtbtu)SbX2(μ‐X)2(μ‐dtbtu)SbX2(dtbtu)], (X = Cl, 1; X = Br, 2), which feature one bridging dtbtu ligand and two bridging halides. The geometry at antimony is highly distorted octahedral. This distortion is partly due to the bridging ligands, but there is also evidence for the presence of stereochemically active lone pairs. In 1 the lone pair appears to be located towards an edge of the octahedron between a terminal and a bridging halide. The situation is similar in 2, but the distortion is considerably greater at one of the antimony atoms than at the other. In contrast, the reaction of dtbtu with SbI3 yields a 1:1 complex, [SbI3(dtbtu)] (3), which is likely to be polymeric with bridging iodide ligands. The low solubility of the iodide complex has precluded characterisation by X‐ray crystallography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Structure and Shape Evolution of Bi1–xLaxFeO3 Perovskite Microcrystals by Molten Salt Synthesis
Authors: Chen Jun , Yu Ranbo , Li Lihong , Sun Ce , Zhang Teng , Chen Houwen , Xing Xianran
Published: July 2008

A facile and environmentally friendly synthesis method has been employed to prepare micron or submicron single‐crystal Bi1–xLaxFeO3 with different particle shapes. Various forms of the crystallite are obtained, such as cubic, tetragonal, and semi‐sphere crystallites, by means of molten salt synthesis. The thermal stability of BiFeO3 perovskite is greatly enhanced by substitution with LaFeO3. The pure phase ofBi1–xLaxFeO3 can be obtained without the use of the rapid thermal technique by introducing with small amounts of LaFeO3 into BiFeO3. The structure of Bi1–xLaxFeO3 changes from rhombohedral BiFeO3 (R3c) to orthorhombic LaFeO3 (Pnma) with an intermediate orthorhombic phase (C222), which is demonstrated by the X‐ray diffraction, Raman spectoscopy, and electron diffraction. The formation of Bi1–xLaxFeO3 can be completed in a short time (i.e. 30 min), as the reaction temperature reaches the melting point of NaCl. For the synthesis of Bi0.4La0.6FeO3, the nuclei occur with an irregular tetragonal shape in the initial nucleation stage and then grow with a regular tetragonal profile in the following growth stage. The Bi1–xLaxFeO3 crystal growth was revealed to follow the Ostwald ripening mechanism.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
19F NMR Spectroscopic Investigation of the Reaction of Bis(pentafluorophenyl)borinic Acid with a “Proton Sponge”: Deprotonation, Trimerization and Stepwise Dearylation
Authors: Donghi Daniela , Maggioni Daniela , Beringhelli Tiziana , D'Alfonso Giuseppe
Published: July 2008

The reaction of Ar2BOH (1, Ar = C6F5) with the proton sponge bis(dimethylamino)naphthalene (DMAN) in CD2Cl2 solution caused a series of strictly interlaced processes that have been investigated by variable‐temperature 1H and 19F NMR spectroscopy. The very slow equilibrium between the monomeric and cyclic trimeric forms of Ar2BOH was strongly accelerated by the presence of a catalytic amount of DMAN. Upon addition of stoichiometric DMAN (0.33 equiv.), all Ar2BOH was converted into a mixture of two boroxinate anions, namely [Ar6B3O3H2]– (2) and [Ar5B3O3H]– (3), in which the ratio of the two anions varied according to the reaction conditions. The formation of the dearylated anion 3 (accompanied by equimolar pentafluorobenzene) has been attributed to a reaction process parallel to that leading to the hexaaryl anion 2, involving base‐catalyzed hydrolysis of monomeric perfluoroborinic acid to its boronic analogue, followed by aggregation and condensation. Water plays a catalytic role in this process. In the presence of a small excess of DMAN, complete and instantaneous dearylation of 2 to 3 was observed. At temperatures lower than 233 K, the pentaaryl anion 3 was in equilibrium with its conjugate base. Slow further dearylation occurred at temperatures higher than 263 K, cleanly affording the tetraaryl anion [Ar4B3O3]– (5). Anions 3 and 5 have also been obtained in high yields from the condensation reaction between Ar2BOH and ArB(OH)2 (in the ratio 2:1 and 1:2, respectively), in the presence of stoichiometric DMAN. Mechanisms responsible for the stepwise dearylation from 2 to 3 and then from 3 to 5 have been discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Hydrocarboxylation of Terminal Alkenes in Supercritical Carbon Dioxide
Authors: Tortosa Estorach Clara , Orejón Arantxa , Ruiz Núria , Masdeu‐Bultó Anna M. , Laurenczy Gábor
Published: July 2008

The catalytic hydrocarboxylation of linear alkenes to carboxylic acids using supercritical carbon dioxide as a solvent was studied. High selectivities in acids have been obtained. The best results were achieved when adding a perfluorinated surfactant to the reaction mixture (93 % conversions and ca. 80 % selectivity). Comparative multinuclear high‐pressure NMR spectroscopic studies in [D8]THF and in supercritical CO2show the formation of Pd0species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Silver(I) and Copper(I) Coordination Polymers Based on Thiaoxa‐Macrocycles
Authors: Kim Hyun Jee , Song Mi Ryoung , Lee So Young , Lee Jai Young , Lee Shim Sung
Published: July 2008

Two S2O2‐macrocycles with different ring size (L1: 17‐ and L2: 18‐membered) were synthesised and structurally characterised by X‐ray analysis. Reactions of L1 and L2 with silver(I) salts (ClO4– and NO3–) afforded respective ligand‐ and/or anion‐directed complexes 1–4 with different topologies; single‐stranded 1D coordination polymer [AgL1(ClO4)(DMSO)]n (1), double‐stranded 1D coordination polymer {[Ag2(L1)2(NO3)2]·DMSO}n (2), cyclic dimer [Ag2(L2)2(ClO4)2]·CH2Cl2·CH3OH (3) and 2D polymeric sheet [Ag(L2)NO3]n (4). Meanwhile, reactions of these two ligands with copper(I) iodide afforded 1D (5) and 2D (6a) coordination polymers linked with a rhomboid‐type Cu–I2–Cu unit, respectively. The formation of such discrete and continuous supramolecular complexes is discussed in terms of discrimination of the anion effect, ligand flexibility as well as interligand π‐π stacking interaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Substituent Effects in the Solid‐State Assembly of Silver(I) Complexes of 4‐Substituted 3,6‐Di(2‐pyridyl)pyridazines
Authors: Constable Edwin C. , Housecroft Catherine E. , Neuburger Markus , Reymann Sébastien , Schaffner Silvia
Published: July 2008

The reactions of one equivalent of silver(I) tetrafluoroborate with one equivalent of 4‐R‐3,6‐di(2‐pyridyl)pyridazine ligands (R = n‐C10H21, 4‐O2NC6H4, 4‐MeOC6H4, 4‐F3CC6H4, 4‐NCC6H4, 3,5‐Br2C6H3, 3,5‐(MeO)2C6H3) in acetonitrile are reported. All complexes have been structurally characterized, and are found to belong to one of four differentsolid‐state structure types: [AgL2][BF4], [Ag2L2][BF4]2, {[Ag3L2][BF4]3}n and {[Ag2(NCMe)2L2][BF4]2}n. For the bulk samples of these compounds, elemental analyses are consistent with formulations of [AgL2][BF4], [Ag2L2][BF4]2, but the two polymeric complexes analyse as 1:1 Ag:L complexes. In solution, 1H and 13C NMR spectra reveal only one ligand environment at room temperature for each product.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
N‐Heterocyclic Carbenes in Lewis Acid/Base Stabilised Phosphanylboranes
Authors: Adolf Ariane , Vogel Ulf , Zabel Manfred , Timoshkin Alexey Y. , Scheer Manfred
Published: July 2008

The reactions of 2‐borane‐1,3,4,5‐tetramethylimidazoline (BH3·NHCMe) with selected phosphane adducts of the Lewis acids B(C6F5)3 and Ga(C6F5)3 are studied. Among others, adducts (C6F5)3Ga·PH2Cp* (1a) and (C6F5)3B·PH2Cp* (2) are used as starting materials. When the (C6F5)3Ga–phosphane adducts 1a and (C6F5)3Ga·PPhH2 are treated with BH3·NHCMe, the Lewis acid/base stabilised phosphanylboranes (C6F5)3Ga·P(Cp*)HBH2·NHCMe (3a) and (C6F5)3Ga·P(Ph)HBH2·NHCMe (3b) are formed, respectively, by a hydrogen elimination reaction. In contrast, the reaction of BH3·NHCMe with the (C6F5)3B–phosphane adducts (C6F5)3B·PH2R [R = H, R = Cp* (2) and R = Ph] in CH2Cl2 at room temperature leads to the formation of a salt with the general formula [(C6F5)3BH][RPH2·BH2·NHCMe] (4a: R = H, 4b: R = Cp*, 4c: R = Ph). To synthesise the Lewis acid/base stabilised phosphanylborane with (C6F5)3B as a Lewis acid and 1,3,4,5‐tetramethylimidazolylidene (NHCMe) as a Lewis base, a different synthetic pathway was applied: the replacement reaction of the Lewis base. At room temperature, NHCMe displaced the amine in (C6F5)3B·P(Ph)HBH2·NMe3 to yield (C6F5)3B·P(Ph)HBH2·NHCMe (5). All compounds were comprehensively characterised by spectroscopic methods. Compounds 1a, 1b, 2, 3a, 3b and 5 were additionally characterised by X‐ray crystallographic analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Copper(II) Complexes of Tridentate Schiff Bases of 5‐Substituted Salicylaldehydes and Diamines – The Role of the Substituent and the Diamine in the Formation of Mono‐, Di‐ and Trinuclear Species – Crystal Structures and Magnetic Properties
Authors: Rigamonti Luca , Cinti Antonio , Forni Alessandra , Pasini Alessandro , Piovesana Olivo
Published: July 2008

We describe some copper(II) complexes with tridentate anionic Schiff bases, L–, derived from the monocondensation of some 5‐substituted salicylaldehydes (5‐G‐salH, G = H, NO2 and OMe) with ethylenediamine (en) or 1,3‐diaminopropane (tn). Mononuclear [CuL(py)]+, dinuclear [Cu2L2]2+ and trinuclear [Cu3L3(μ3‐OH)]2+ compounds have been obtained, and factors affecting the nuclearity of complexes were investigated and found to depend on reaction conditions, the nature of G and the length of the diamine. The crystal structures of seven representative compounds have been determined. Magnetic studies on a dinuclear and a trinuclear species were also carried out, and the results were interpreted on the basis of the structural data and current superexchange models. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Iron and Cobalt Complexes of Tridentate N‐Donor Ligands in Ethylene Polymerization: Efficient Shielding of the Active Sites by Simple Phenyl Groups
Authors: Zabel Dirk , Schubert Anett , Wolmershäuser Gotthelf , Jones Robert L. , Thiel Werner R.
Published: July 2008

Tridentate 2,6‐bis[3(5)‐pyrazolyl]pyridines and 2,6‐bis(4‐pyrimidinyl)pyridine were synthesized and characterized spectroscopically and by single‐crystal X‐ray structure analysis. The derived complexes with FeCl2 and CoCl2 were investigated for their activity in the ethylene polymerization in the presence of methylalumoxane (MAO). Iron and cobalt catalysts bearing the ligand 2,6‐bis[5‐butyl‐1‐(4‐nitrophenyl)pyrazol‐3‐yl]pyridine showed moderate catalytic activity and gave PE with high molecular weight, although the aryl substituents are not equipped with additional bulky side chains in the 2,6‐positions to shield the metal centre. This can be explained by the geometric parameters of the pyrazole units, which provide efficient shielding of the active site, even with unsubstituted aryl groups. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis, Structure, Spectroscopic Studies and Magnetic Properties of the Tetrakis(5,7‐dichloro‐8‐quinolinolato)gadolinium(III) Complex
Authors: Artizzu Flavia , Bernot Kevin , Caneschi Andrea , Coronado Eugenio , Clemente‐Juan Juan M. , Marchiò Luciano , Mercuri Maria Laura , Pilia Luca , Serpe Angela , Deplano Paola
Published: July 2008

The synthesis and structural characterization of the neutral gadolinium tetrakis‐type complex with 5,7‐dichloro‐8‐quinolinolato (H5,7ClQ) ligands, [Gd(5,7ClQ)2(H5,7ClQ)2Cl], is reported. The GdIII ion is epta coordinated to one chloride ion and to four ligands: two N,O‐chelated monoanions and two as zwitterionic (+NH and O–) monodentate oxygen donors. Electronic and vibrational spectra provide suitable markers to distinguish the presence of deprotonated and protonated ligands. The magnetic behaviour of this compound was investigated and explained by taking into account that π–π stacking interactions between the (H5,7ClQ) ligands give rise to a ferromagnetic interaction between the gadolinium centres. The GdIII derivatives provide magnetic evidence for the presence of stacking interactions, which are usually undetectable in optically active ErIII derivatives.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Tetrahedral Assembly with Lanthanides: Toward Discrete Polynuclear Complexes
Authors: Hamacek Josef , Bernardinelli Gérald , Filinchuk Yaroslav
Published: July 2008

We report on the preparation of discrete 3D tetrametallic edifices containing trivalent lanthanides (Eu–Lu). Their formation is thermodynamically controlled through self‐assembly with a new tripodal ligand L possessing short binding strands. X‐ray crystallography shows that four nine‐coordinate cations adopt a regular tetrahedral arrangement in the solid state. These remarkable, highly charged structures are maintained in solution, as demonstrated by NMR spectroscopy, ESI‐MS and spectrophotometry.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Chlorinated Biphenyls by Suzuki Cross‐Coupling Using Diamine or Diimine‐Palladium Complexes
Authors: Kylmälä Tuula , Kuuloja Noora , Xu Youjun , Rissanen Kari , Franzén Robert
Published: July 2008

Several novel diimines (Salen‐type ligands) 2a–2i and their reduced diamine counterparts 3b,3d–3g and 3i form complexes 4a–4i, 5b,5d–5g, and 5i with PdCl2 in DMF or methanol. Using 1 mol‐% of the isolated complexes 4e and 5f many polychlorinated biphenyls (PCBs) can be prepared in moderate to excellent yields according to the Suzuki cross‐coupling protocol with contact to air. Several 4‐acetylbiphenyls prepared by this method can be converted in moderate yields into the corresponding biphenylcarboxylic acids (BCAs) by alkaline cleavage. An X‐ray crystal structure determination confirms the structure of complex 5f.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Optically Active (Peptido‐carbene)palladium Complexes: Towards True Solid‐Phase Combinatorial Libraries of Transition Metal Catalysts
Authors: Jensen Jakob F. , Worm‐Leonhard Kasper , Meldal Morten
Published: July 2008

This work explores the potential of forming transition metal catalysts by combinatorial solid‐phase peptide chemistry to produce catalysts with enzyme‐like properties of stereoselectivity, regioselectivity and even substrate selectivity. A series of new functionalised carbene precursors/donors – imidazolium salts – each containing both amino acid and carboxylic acid functionality was synthesised in solution. The readily accessible carbene precursors were incorporated within the backbones of peptides attached to PEGA resin, by standard solid‐phase peptide coupling techniques. The synthetic strategy gave easy access to both mono‐ and didentate ligand systems, providing folded structures around the central transition metal atoms, with different degrees of steric congestion and bite angles. Changing the number of incorporated amino acids between the two carbene donors facilitated variation of the properties of the complexes. Both ligand systems were complexed to palladium(II) by standard base treatment, and the Pd complexes were studied by mass spectrometry and NMR spectroscopy. The monodentate (carbene)palladium complexes were each the product of enolisation of a neighbouring carbonyl group and loss of a proton, followed by coordination of the oxy anion to the palladium atom. The established methods are suitable for the combinatorial synthesis of palladium catalysts on solid support. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Catalytic Hydrogenation of 5,6‐Dihydro‐4H‐1,2‐oxazines Bearing a Functionalized Methylene Group at C‐3
Authors: Sukhorukov Alexey Yu. , Lesiv Alexey V. , Eliseev Oleg L. , Khomutova Yulia A. , Ioffe Sema L. , Borissova Alexandra O.
Published: July 2008

The catalytic hydrogenation of readily available methyl 2‐(5,6‐dihydro‐4H‐1,2‐oxazin‐3‐yl)acetates 6 has been studied. Dihydrooxazines 6 without an alkoxy substituent at C‐6 under mild hydrogenation conditions in methanol produce a dynamic mixture of enamines 7 and tetrahydro‐2‐furanamines 7′(α + β). These products can be transformed into 1,4‐amino alcohols 8 under more robust hydrogenation conditions or into isomeric dihydrofurans 9 and 10 if the reduction is carried out in glacial acetic acid. Reduction of dihydrooxazines 6h,i, which possess an alkoxy substituent at C‐6, under similar conditions affords pyrrolidine derivatives 12, 13 and 14. A general mechanistic scheme for the hydrogenation reaction that involves an initial N–O bond cleavage has been suggested. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Reusable Porphyrinatoiron(III) Complex Supported on Activated Silica as an Efficient Heterogeneous Catalyst for a Facile, One‐Pot, Selective Synthesis of 2‐Arylbenzimidazole Derivatives in the Presence of Atmospheric Air as a “Green” Oxidant at Ambient Temperature
Authors: Sharghi Hashem , Beyzavi Mohammad Hassan , Doroodmand Mohammad Mahdi
Published: July 2008

An efficient and highly selective synthesis of 2‐arylbenzimidazoles by condensation of a wide range of aryl aldehydes bearing electron‐donating or ‐withdrawing substituents and phenylenediamines in a single pot using a catalytic amount of (meso‐tetrakis(o‐chlorophenyl)porphyrinato)iron(III) chloride (5 mol‐%) in excellent isolated yields is described. The reactions were performed in the presence of atmospheric air as a “green” oxidant at ambient temperature in ethanol without any additives. To benefit from the recovery and reuse of the catalyst, a new iron(III) porphyrin–silica heterogeneous catalyst was prepared by simple and successful impregnation of (meso‐tetrakis(o‐chlorophenyl)porphyrinato)iron(III) chloride onto activated commercial chromatographic silica gel. The silica was modified by treatment with HCl solution followed by NaOH solution, giving rise to the transformation of –O– strained siloxane atoms and silanol–OH groups into terminal negatively charged silanol–O– groups. The heterogeneous catalyst was characterized by powdered X‐ray diffraction (XRD), scanning electronic microscopy (SEM), atomic force microscopy (AFM), thermogravimetry (TG) to analyse for nitrogen adsorption, and Raman and FTIR spectroscopy. Leaching experiments showed that the catalyst is most strongly anchored to the activated support after 10 cycles. T(o‐Cl)PPFeIII–SiO2 was successfully used for all runs performed by the homogeneous catalyst and exhibited high isolated yields, selectivity, reusability, and the potential for large‐scale synthesis. Mechanistically, the high‐valent oxido‐iron(IV)–porphyrin could be the key intermediate in this efficient and highly selective synthesis of benzimidazole derivatives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Lewis Acid Catalyzed Addition of Pyrazoles to Alkynes: Selective Synthesis of Double and Single Addition Products
Authors: Tsuchimoto Teruhisa , Aoki Kazuki , Wagatsuma Tatsuya , Suzuki Yuichi
Published: July 2008

Silver and zinc salts were found to efficiently catalyze the addition of an N–H bond of pyrazoles to alkynes. With silver triflate as a catalyst, two pyrazoles regioselectively attacked the same carbon atom of the C≡C bond of aliphatic terminal alkynes to give gem‐dipyrazolylalkanes predominantly. Replacement of silver triflate with zinc triflate allows us to achieve double addition of pyrazoles to aromatic terminal alkynes. In contrast to the selective double addition, the corresponding single addition of aliphatic and aromatic terminal alkynes exclusively proceeded in the presence of a catalytic amount of silver nitrate. Internal alkynes also participated in the single addition reaction with the aid of silver triflate as a catalyst. The notable feature of this protocol is the utilization of an addition reaction being optimal from environmental and atom‐economical points of view. The reaction mechanism is also described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis and Phase Structures of Novel π‐Acceptor Discotic Liquid Crystalline Compounds Having a Pyrenedione Core
Authors: Yasutake Mikio , Fujihara Takashi , Nagasawa Akira , Moriya Keiichi , Hirose Takuji
Published: July 2008

Several π‐acceptor discotic liquid crystalline compounds were synthesized by using a pyrenedione unit as a core. Terrace‐like and band‐like structures were revealed by polarized optical microscopy (POM) observations and XRD measurements. In conjunction with the results of the single‐crystal structure analysis of analogous crystalline compounds, all of the liquid crystalline compounds were confirmed to form a discotic lamellar phase DL2. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Elimination Mechanisms in the Aminolysis of Sulfamate Esters of the Type NH2SO2OC6H4X – Models of Enzyme Inhibitors
Authors: Spillane William J. , O'Byrne Andrew , McCaw Cheryl J. A.
Published: July 2008

The kinetics of the reaction of 4‐nitrophenyl sulfamate NH2SO2OC6H4NO2‐4 (1a) in acetonitrile (ACN) with a series of pyridines (pKa range ca. 8 units) and alicyclic amines (pKa range ca. 3.6 units) has been studied in the presence of excess amine at various temperatures. The compounds 1a–1f are important as model substrates for the medicinally important sulfamate esters 667‐coumate and emate and analogues. Pseudo‐first‐order rate constants (kobsd.) have been obtained mainly by the release of 4‐nitrophenol/4‐nitrophenoxide. Slopes of plots of kobsd. vs. [amine] gave second‐order rate constants (k2), and Brönsted plots were biphasic for the aminolysis (with alicyclic amines) with an initial slope β1 = 0.53 and a subsequent slope β2 = 0.19. The change in slope occurs near the first pKa of 1a (17.9) in ACN. Leaving‐group effects were probed by using the same series of phenyl sulfamates, i.e. 1a–f and the alicyclic amines N‐formylpiperazine and pyrrolidine. The reactions were considered to be dissociative in nature involving E2‐ and E1cB‐ type mechanisms with the phenyl sulfamate anion 2 being involved in pyridine and in the weaker alicyclic amines (β1 segment) and a phenyl sulfamate dianion 3 being involved with the stronger alicyclic bases (β2 segment). The calculation of Leffler indices (α) for bond‐forming (base···H+) and bond‐breaking (S–OAr) steps allows fuller interpretation of the mechanisms occurring, which are seen as having the N‐sulfonylamines, HN=SO2 and –N=SO2 on the reaction pathways leading to products. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Modular Routes Towards New N,O‐Bidentate Ligands Containing an Electronically Delocalised β‐Enaminone Chelating Backbone
Authors: Beckmann Udo , Eichberger Eva , Lindner Monika , Bongartz Melanie , Kunz Peter C.
Published: July 2008

Polyketones are synthesised by a transition‐metal‐catalysed copolymerisation of olefins and carbon monoxide. Nickel complexes with N,O‐chelating ligands turned out to be promising catalysts in that field. In this work a series of new N,O ligands with an electronically delocalised β‐enaminone backbone were synthesised and fully characterised. The ligand design was inspired by the ligand found in the most efficient nickel catalyst for polyketone synthesis and developed to a highly modular LEGO®‐like arsenal of reactions to versatile substituted β‐enaminone ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Convergent and Selective Synthesis of Pyrrolidinones, Piperidinones, Dihydropyridinones and Pyridinols from a Common Intermediate – Potential Precursors of Bioactive Products
Authors: Jida Mouhamad , Ollivier Jean
Published: July 2008

Titanium‐mediated cyclopropanation of natural and unnatural β‐amino acid derivatives provides azabicyclo[3.1.0]hexan‐1‐ols as mixtures of diastereomers that are separable by silica‐gel chromatography. Depending on the ring cleavage procedure employed, these compounds lead efficiently to diverse intermediates for the synthesis of pharmaceuticals. Thus, depending on the experimental conditions, basic treatment can furnish racemic pyrrolidinones as a mixture of diastereomers and piperidinones. In contrast, the synthesis of optically active dihydropyridinones was achieved through a one‐pot FeCl3/AcONa reaction or performed by using bis(sym‐collidine)iodine hexafluorophosphate. Furthermore, whereas the palladium‐mediated hydrogenolysis of these dihydropyridinones furnished both chiral piperidinones and original pyridinols, a CeIV‐promoted radical process yielded chiral tricyclic piperidinones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
The Use of a Bifunctional Copper Catalyst in the Cross‐Coupling Reactions of Aryl and Heteroaryl Halides with Terminal Alkynes
Authors: Wu Minyan , Mao Jincheng , Guo Jun , Ji Shunjun
Published: July 2008

Copper‐catalyzed cross‐coupling reactions of aryl halides and heteroaryl halides with terminal alkynes were carried out in DMF at 110–130 °C to provide the corresponding coupling products in satisfactory‐to‐good yields by using inexpensive 8‐hydoxyquinoline as the ligand. Noteworthy is that the bifunctional copper catalyst was successfully applied in this alkynylation reaction for the first time.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Catalytic Version of and Reuse in Hypervalent Organo‐λ3‐ and ‐λ5‐iodane Oxidation
Authors: Ochiai Masahito , Miyamoto Kazunori
Published: July 2008

Hypervalent organoiodanes are one of the most valuable classes of oxidants for use in oxidative transformations of various kinds of functionalities in modern organic synthesis. This microreview provides an overview of the recently developed aryl iodide‐catalyzed oxidations, in which hypervalent organoiodanes(III and V) generated in situ serve as the actual oxidants. We also summarize recent attempts to improve the efficiency of recyclable hypervalent organoiodanes in oxidations, updating Togo's and Sakuratani's 2002 review.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Stannylated Allyl‐ and Vinylphosphonates via Molybdenum‐Catalyzed Hydrostannations
Authors: Jena Nivedita , Kazmaier Uli
Published: July 2008

Syntheses of stannylated allyl and vinylphosphonates by molybdenum‐catalyzed hydrostannation of the corresponding propargyl‐ and alkynylphosphonate derivatives proceed with high regioselectivities. The stannylated phosphonates obtained are versatile building blocks for further modifications, such as iodinations or cross coupling reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
γ‐(Hydroxyalkyl)naphthalene‐tetracarboxdiimides: Organic White Pigments
Authors: Langhals Heinz , Ritter Ulrike
Published: July 2008

Naphthalene‐1,8:4,5‐tetracarboxdiimides were prepared from cyanoacetic acid and its alkylation, reduction and condensation with naphthalenetetracarboxylic dianhydride and exhibit strong light‐scattering and opacifying properties. Applications are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Some 2,2′:6′,2″‐Terpyridines Disubstituted in Positions 6 and 6″ with Head‐to‐Tail Oriented Amino Acids and Dipeptides: A Simple Entry to a Reversible Inducer of Folding in Amino Acid Sequences
Authors: Annunziata Rita , Benaglia Maurizio , Puglisi Alessandra , Raimondi Laura , Cozzi Franco
Published: July 2008

The 2,2′:6′,2″‐terpyridine scaffold has been identified as a conformationally discrete structural element potentially capable of inducing reversible folding in substituents, attached through suitable spacers to its 6,6″‐positions, by metal complexation/decomplexation or by protonation/deprotonation. The synthesis of some terpyridine–amino acids and terpyridine–dipeptide conjugates is described. The assembly of these conjugates has been achieved by connecting NH2‐ and CO2H‐protected glycine, alanine, and valine residues or antiparallel oriented AlaGly/GlyAla chains to the terpyridine scaffold through phenylacetylene spacers. Preliminary experiments showed that upon addition of Zn2+ to the amino acid substituted transoid terpyridine systems, folded cisoid complexes were formed. Also, bis(protonation) of the dipeptide‐substituted system resulted in the formation of a folded adduct. Reversibility of the folding process was shown by Zn2+ removal with triethylamine or deprotonation with aqueous ammonia. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A New One‐Pot Synthetic Approach to the Highly Functionalized (Z)‐2‐(Buta‐1,3‐dienyl)phenols and 2‐Methyl‐2H‐chromenes: Use of Amine, Ruthenium and Base‐Catalysis
Authors: Ramachary Dhevalapally B. , Narayana Vidadala V. , Ramakumar Kinthada
Published: July 2008

A practical and simple one‐pot multi‐catalysis process for the synthesis of highly substituted benzo[b]oxepines 5, (Z)‐2‐(buta‐1,3‐dienyl)phenols 6 and 2‐methyl‐2H‐chromenes 7 from simple starting materials was achieved for the first time through ring‐closing metathesis/base‐induced ring opening/[1,7]‐sigmatropic hydrogen shift reactions. The synthesis of privileged (Z)‐2‐(buta‐1,3‐dienyl)phenols 6 via base‐induced ring opening of highly functionalized benzo[b]oxepines 5 is described(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Functionalized Isobenzomorphans by Two‐Step Cyclocondensation of 1,3‐Bis(trimethylsilyloxy)‐1,3‐butadienes with Isoquinolines
Authors: Yawer Mirza A. , Hussain Ibrar , Gütlein Jörg‐Peter , Schmidt Andreas , Jiao Haijun , Reinke Helmut , Spannenberg Anke , Fischer Christine , Langer Peter
Published: July 2008

A great variety of functionalized 7,8‐benzo‐anellated 9‐azabicyclo‐[3.3.1]nonan‐3‐ones were prepared by methyl or benzyl chloroformate‐mediated condensation of isoquinolines with 1,3‐bis(silyloxy)‐1,3‐butadienes and subsequent TFA‐mediated cyclization. The hydroxy group could be functionalized by Suzuki reactions of the corresponding enol triflates. The N‐benzyloxycarbonyl‐substituted products were successfully deprotected. The decarboxylation allowed the synthesis of the parent 7,8‐benzo‐anellated 9‐azabicyclo[3.3.1]nonan‐3‐ones. The products can be regarded as functionalized isobenzomorphans – simple structural analogues of morphine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Hyperbranched rolling circle amplification as a rapid and sensitive method for species identification within the Cryptococcus species complex
Authors: Kaocharoen Sirada , Wang Bin , Tsui Kin Ming , Trilles Luciana , Kong Fanrong , Meyer Wieland
Published: July 2008

The Cryptococcus species complex contains two closely related basidiomycetous yeasts: Cryptococcus neoformans and C. gattii, which cause cryptococcosis in humans and other animals. The species and varieties are characterized, by different clinical, epidemiological, biochemical and molecular features. The currently used identification methods are either time‐consuming or not anymore commercially available. However, a rapid, sensitive and robust assay for the detection of these pathogens is vital for early diagnosis and appropriate treatment decisions. To overcome those limitations, four padlock probes targeting species‐specific single nucleotide polymorphisms at the internal transcribed spacers (ITSs) of the RNA gene locus were developed and applied during isothermal hyperbranched rolling circle amplification (HRCA). The probes were tested against 99 samples, including 94 clinical cryptococcal cultures, three closely related Cryptococcus species, and two clinical specimens. The use of the padlock probes and the combination of probe signal amplification by HRCA provided a quick and sensitive assay for the accurate identification of C. neoformans var. grubii, C. neoformans var. neoformans and C. gattii. HRCA was also useful to detect hybrids, when they were heterozygous at the ITS locus. The HRCA results were in agreement with previous genotyping data based on PCR fingerprinting, amplified fragment length polymorphism and ITS sequencing.
Simultaneous determination of p‐hydroxybenzoic acid and parabens by capillary electrophoresis with improved sensitivity in nonaqueous media
Authors: Blanco Eva , Casais María del Carmen , Mejuto María del Carmen , Cela Rafael
Published: July 2008

New methods based on nonaqueous capillary electrophoresis (NACE) were developed as promising alternatives for the simultaneous separation and determination of p‐hydroxybenzoic acid (PHBA) and a group of parabens (methyl, ethyl, propyl, butyl and benzyl p‐hydroxybenzoates), with good resolution and excellent sensitivity. As an effective on‐line preconcentration technique, large‐volume sample stacking (LVSS) was successfully combined with NACE allowing significant sensitivity enhancement. Identification and quantification of the analytes were performed by diode array detection (DAD). The influence of different parameters, such as buffer apparent pH, concentration of electrolyte, temperature, applied voltage and sample volume, on the efficiency, resolution and sensitivity of the electrophoretic separation was studied. The analytical performance was evaluated, and both NACE‐DAD and LVSS‐NACE‐DAD methods showed good linearity, precision and instrumental LODs at low ng/mL levels. These LODs were compared with those described in the literature, and it was found that NACE‐DAD method was comparable to GC‐MS, while LVSS‐NACE‐DAD procedure achieved sensitivity similar to LC‐MS, LC‐MS/MS and GC‐MS/MS, even using conventional ultraviolet‐visible absorption detection. To test their suitability, proposed methods were evaluated for the analysis of PHBA and parabens at low and sub‐ng/mL levels in environmental water samples.
A low‐leakage sample plug injection scheme for crossform microfluidic capillary electrophoresis devices incorporating a restricted cross‐channel intersection
Authors: Chang Chin‐Lung , Hou Hui‐Hsiung , Fu Lung‐Ming , Tsai Chien‐Hsiung
Published: July 2008

This study develops a crossform CE microfluidic device in which a single‐circular barrier or a double‐circular barrier is introduced at the cross‐channel intersection. Utilizing a conventional crossform injection scheme, it is shown that these barriers reduce sample leakage and deliver a compact sample band into the separation channel, thereby ensuring an enhanced detection performance. A series of numerical and experimental investigations are performed to investigate the effects of the barrier type and the barrier ratio on the flow streamlines within the microchannel and to clarify their respective effects on the sample leakage ratio and sample plug variance during the injection process. The results indicate that a single‐circular barrier injector with a barrier ratio greater than 20% and a double‐circular barrier injector with a barrier ratio greater than 40% minimize the sample leakage ratio and produce a compact sample plug. As a result, both injectors have an excellent potential for use in high‐quality, high‐throughput chemical analysis procedures and in many other applications throughout the micro‐total analysis systems field.
Epstein–Barr virus upregulates phosphorylated heat shock protein 27 kDa in carcinoma cells using the phosphoinositide 3‐kinase/Akt pathway
Authors: Fukagawa Yuki , Nishikawa Jun , Kuramitsu Yasuhiro , Iwakiri Dai , Takada Kenzo , Imai Shousuke , Satake Masaaki , Okamoto Takeshi , Fujimoto Masanori , Okita Kiwamu , Nakamura Kazuyuki , Sakaida Isao
Published: July 2008

Gastric cancer is the most common cancer in Japan and infection with Epstein–Barr virus (EBV) is responsible for about 10% of gastric cancers worldwide. Although EBV infection may be involved at an early stage of gastric carcinogenesis, the mechanisms underlying its involvement remain unknown. To investigate the role of EBV in gastric carcinogenesis, we performed proteomic analyses of an EBV‐infected gastric carcinoma cell line NU‐GC‐3 (EBV(+)) and its uninfected control (EBV(−)). 2‐DE was combined with MS to identify differentially expressed proteins. We found that EBV infection upregulated one of the phosphorylated heat shock protein 27 kDa (HSP27). The phosphorylated HSP27 isoform which increased in EBV(+) cells can be induced by both heat shock and arsenite. The increase of phosphorylated HSP27 in EBV(+) cells was reduced by treatment with the phosphoinositide 3‐kinase (PI3K) inhibitors (LY294002 and wortmannin). In addition, we found increased levels of phosphorylated Akt in EBV(+) cells. These findings suggest that EBV infection upregulates the phosphorylation of HSP27 via the PI3K/Akt pathway. Thus, activation of the PI3K/Akt pathway may contribute to the establishment of a malignant phenotype in EBV‐infected gastric carcinomas.
Supercritical fluid extraction as an on‐line clean‐up technique for determination of riboflavin vitamins in food samples by capillary electrophoresis with fluorimetric detection
Authors: Zougagh Mohammed , Ríos Ángel
Published: July 2008

An automatic method for the separation and determination of riboflavin (RF) vitamins (RF, flavin mononucleotide and flavin adenine dinucleotide) in food samples (chicken liver, tablet and powder milk) is proposed. The method is based on the on‐line coupling of a supercritical fluid extractor (SFE) with a continuous flow‐CE system with guided optical fiber fluorimetric detection (CF‐CE‐FD). The whole SFE‐CF‐CE‐FD arrangement allowed the automatic treatment of food samples (clean‐up of the sample followed by the extraction of the analytes), and the direct introduction of a small volume of the extracted plug to the CE‐FD system for the determination of RF vitamins. Fluorescence detection introduced an appropriated sensitivity and contributed to avoid interferences of nonfluorescent polar compounds coming from the matrix samples in the extracted plug. Electrophoretic responses were linear within the 0.05–1 μg/g range, whereas the detection limits of RF vitamins were in the 0.036–0.042 μg/g range. The proposed arrangement opens up interesting prospects for the direct determination of polar analytes in complex samples with a good throughput and high level of automation.
Characterization of poly(4‐vinylpyridine 1‐oxide) by free‐solution capillary electrophoresis and micellar electrokinetic chromatography
Authors: Beneito‐Cambra Miriam , Herrero‐Martínez José M. , Ramis‐Ramos Guillermo
Published: July 2008

The migration characteristics of poly(4‐vinylpyridine 1‐oxide) (PVP‐NO) in phosphate buffers of acidic pH (20 mM H3PO4 or NaH2PO4) have been studied using both free‐solution capillary electrophoresis (FSCE) and MEKC. To inhibit adsorption, 250 mM o‐phosphoethanolamine (2‐aminoethyl dihydrogen phosphate) was used. In FSCE, PVP‐NO showed a narrow peak and a broader band, both having anionic behavior. These peak and band were attributed to the free and aggregated or micellized PVP‐NO forms, respectively. According to surface tension measurements, the CMC of SDS in the BGE was 1.8 and 0.48 mM in the absence and in the presence of 1000 µg/mL PVP‐NO, respectively, and the association of the polymer with SDS was completed at 9.7 mM SDS. Using MEKC, a narrow peak and a broader band also appeared at SDS concentrations of ca. 1 mM, and their intensity increased with the SDS concentration. These peak and band were attributed to the formation of mixed micelles constituted by both free PVP‐NO/SDS and aggregated PVP‐NO/SDS, respectively. The determination of PVP‐NO by FSCE in commercial additives for laundry was demonstrated.
Identification of shrimp species in raw and processed food products by means of a polymerase chain reaction‐restriction fragment length polymorphism method targeted to cytochrome b mitochondrial sequences
Authors: Pascoal Ananías , Barros‐Velázquez Jorge , Cepeda Alberto , Gallardo José M. , Calo‐Mata Pilar
Published: July 2008

A novel PCR‐RFLP method has been developed for the identification of six commercially relevant penaeid shrimp species in raw and processed food products. The method can be completed within 8 h. To implement the method, PCR amplification with the crustF/crustR primers, targeted to the amplification of a ca. 181 bp region of the cytochrome b (cytb) mitochondrial gene in penaeid shrimps, was coupled to restriction analysis with CviJI, DdeI and NlaIV. The method was also applied successfully to the identification of shrimp species in complex processed foods, including this type of shellfish as an added‐value food ingredient. The small size of this molecular target facilitates amplification from fresh, frozen, or precooked samples, where DNA fragmentation may be relevant and fragment size critical. We also report the first cytb mitochondrial sequences described to date for the species Farfantepenaeus notialis, Parapenaeus longirostris and Pleoticus muelleri, and these nearly triplicate current knowledge of reference nucleotide sequences in this mitochondrial region for this group of species. The cytb mitochondrial gene may also be considered as a molecular marker for identification and phylogenetic purposes in penaeid shrimp species.
Galectin‐3/MAC‐2, Ras and PI3K activate complement receptor‐3 and scavenger receptor‐AI/II mediated myelin phagocytosis in microglia
Authors: Rotshenker Shlomo , Reichert Fanny , Gitik Miri , Haklai Ronit , Elad‐Sfadia Galit , Kloog Yoel
Published: July 2008

The removal of degenerated myelin is essential for repair in Wallerian degeneration that follows traumatic injury to axons and in autoimmune demyelinating diseases (e.g., multiple sclerosis). Microglia can remove degenerated myelin through phosphatidylinositol‐3‐kinase (PI3K)‐dependent phagocytosis mediated by complement receptor‐3 (CR3/MAC‐1) and scavenger receptor‐AI/II (SRAI/II). Paradoxically, these receptors are expressed in microglia after injury but myelin is not phagocytosed. Additionally, Galectin‐3/MAC‐2 is expressed in microglia that phagocytose but not in microglia that do not phagocytose, suggesting that Galectin‐3/MAC‐2 is instrumental in activating phagocytosis. S‐trans, trans‐farnesylthiosalicylic (FTS), which inhibits Galectin‐3/MAC‐2 dependent activation of PI3K through Ras, inhibited phagocytosis. K‐Ras‐GTP levels and PI3K activity increased during normal phagocytosis and decreased during FTS‐inhibited phagocytosis. Galectin‐3/MAC‐2, which binds and stabilizes active Ras, coimmunoprecipitated with Ras and levels of the coimmunoprecipitate increased during normal phagocytosis. A role for Galectin‐3/MAC‐2 dependent activation of PI3K through Ras, mostly K‐Ras, is thus suggested. An explanation may thus be offered for deficient phagocytosis by microglia that express CR3/MAC‐1 and SRAI/II without Galectin‐3/MAC‐2 and efficient phagocytosis when CR3/MAC‐1 and SRAI/II are co‐expressed with Galectin‐3/MAC‐2. © 2008 Wiley‐Liss, Inc.