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Dichloride
Kinds of Dichloride Terms modified by Dichloride Selected AbstractsOne-Pot Synthesis of Carbamoyl Azides Directly from Primary Alcohols and Oxidation of Secondary Alcohols to Ketones Using Iodobenzene Dichloride in Combination with Sodium AzideADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Xiao-Qiang Li Abstract An effective synthesis of carbamoyl azides directly from primary alcohols using iodobenzene dichloride in combination with sodium azide has been developed. Moreover, the same regent combination was also efficient for the oxidation of secondary alcohols to the corresponding ketones. [source] ChemInform Abstract: A Safe, Convenient and Efficient One-Pot Synthesis of ,-Chloroketone Acetals Directly from Ketones Using Iodobenzene Dichloride.CHEMINFORM, Issue 49 2009Jun Yu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Copper Dipyridine Dichloride as a Mild and Efficient Catalyst for a One-Pot Condensation Biginelli Reaction.CHEMINFORM, Issue 48 2005V. Naveen Kumar No abstract is available for this article. [source] Gold Dichloride and Gold Dibromide with Gold Atoms in Three Different Oxidation States.CHEMINFORM, Issue 18 2003Detlef Schroeder Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Reductive Debromination of vic-Dibromides to Alkenes with Bis(cyclopentadienyl)titanium(IV) Dichloride,Indium System.CHEMINFORM, Issue 16 2002Byung Woo Yoo Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Structure of Cyclic Aryl Thioester Dimer Based on o -Phthaloyl Dichloride and Bis(4-mercaptophenyl) SulfideCHINESE JOURNAL OF CHEMISTRY, Issue 4 2003Guo Qing-Zhong Abstract A cyclic aryl thioester dimer was prepared by the reaction of o -phthaloyl dichloride and bis(4-mercaptophenyl) sulfide in good yield under pseudo-high dilution conditions via interfacial polycondensation. The structure of the cyclic dimer was confirmed by a combination of MALDI-TOF-MS, FITR, gel permeation chromatography and NMR analyses. The X-ray diffraction study of the single crystal of cyclic thioester dimer obtained from two solutions reveals no severe internal strain on the cyclic structure. [source] Development of a Novel Automatic Potentiometric System for Determination of Selenium and Its Application in Pharmaceutical Formulations and Anodic SlimeELECTROANALYSIS, Issue 9 2008Ayman Abstract Poly(vinyl chloride) polymeric membrane sensors containing Sn(IV) phthalocyanine dichloride (SnPC) and Co(II) phthalocyanine (CoPC) as novel electroactive materials dispersed in o -nitrophenyl octylether (o -NPOE) as a plasticizer are examined potentiometrically with respect to their response toward selenite (SeO32,) ions. Fast Nernstian response for SeO32, ions over the concentration ranges 7.0×10,6,1.0×10,3 and 8.0×10,6,1.0×10,3 mol L,l at pH,3.5,8.5 with lower detection limit of 5.0×10,6 and 8.0×10,6 mol L,1 and calibration slopes of ,25.4 and ,29.7,mV decade,1 are obtained with SnPC and CoPC based membrane sensors, respectively. The proposed sensors reveals by the modified separate solution method (MSSM) a good selectivity over different anions which differ significantly from the classical Hofmeister series. A segmented sandwich membrane method is used to determine complex formation constants of the ionophores in situe in the solvent polymeric sensing membranes. Membrane incorporating CoPC in a tubular flow detector is used in a two channels flow injection set up for continuous monitoring of selenite at a frequency of ca. 50 samples h,1. Direct determination of selenium in pharmaceutical formulations and anodic slime gives results in good agreement with data obtained using standard ICP method. [source] Reprogramming of a Malonic N-Heterocyclic Carbene: A Simple Backbone Modification with Dramatic Consequences on the Ligand's Donor PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2010Vincent César Abstract Reaction of N,N, -dimesitylformamidine with dimethylmalonyl dichloride in dichloromethane in the presence of an excess of triethylamine gives the 2-chloro-4,5-dioxohexahydropyrimidine 1. The corresponding diamidocarbene 3 is generated in situ by further deprotonation with KHMDS at ,40 °C and identified by trapping with S8 to give the fully characterized (including X-ray structure) sulfur adduct 4. It also reacts with [RhCl(cod)]2 to yield the NHC complex [RhCl(3)(cod)] (5) (characterized also by X-ray structure). The donor properties of 3 were evaluated against the established IR [,(CO)] scale from [RhCl(3)(CO)2] (6). The average value of ,(CO) = 2045 cm,1 indicates that the diamidocarbene 3 is much less nucleophilic than structurally relevant six-membered NHCs including the anionic diaminocarbenes previously reported in our group. [source] Synthesis and Cytotoxicity Studies of Fluorinated Derivatives of Vanadocene YEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2009Brendan Gleeson Abstract From the reaction of 6-(2-fluoro-4-methoxyphenyl)fulvene (1a), 6-(3-fluoro-4-methoxyphenyl)fulvene (1b) and 6-[4-(trifluoromethoxy)phenyl]fulvene (1c) with LiBEt3H, lithiated cyclopentadienide intermediates (2a,c) were synthesised. These intermediates were then transmetallated to vanadium with VCl4 to yield the benzyl-substituted vanadocenes bis[(2-fluoro-4-methoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3a), bis[(3-fluoro-4-methoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3b), and bis[(4-trifluoromethoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3c). The three vanadocenes 3a,c were characterised by single-crystal X-ray diffraction. All three vanadocenes had their cytotoxicity investigated through MTT-based preliminary in-vitro testing on the LLC-PK and Caki-1 cell lines in order to determine their IC50 values. Vanadocenes 3a,c were found to have IC50 values of 6.0 (+/,4), 35 (+/,7) and 13 (+/,3) ,M on the LLC-PK cell line and IC50 values of 78 (+/,11), 18 (+/,16) and 2.2 (+/,0.5) ,M on the Caki-1 cell line respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Structure,Catalytic Activity Relationship in Bridging Silacycloalkyl Ring Conformations of Constrained Geometry Titanium ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2008Eugene Kang Abstract A series of cyclic silylene-bridged (amidocyclopentadienyl)dichlorotitanium(IV) complexes [TiCl2{,5 -1-(CySitBuN- ,N)-2,3,4,5-R4 -C5}] was prepared, where CySi = silacyclobutyl (a), silacyclopentenyl (b), silacyclopentyl (c), and silacyclohexyl (d); R = H (4), Me (5). The starting silane, dichlorosilacycloalkane CySiCl2 (1), was treated with NaCp (LiCp*), followed by LiNHtBu to yield the cyclic silylene-bridged ligands (R4C5)CySi(NHtBu) [R = H (2); Me (3)]. Subsequent deprotonation with n -butyllithium, followed by transmetalation with TiCl4 yielded the desired constrained geometry complexes (CGCs) (CpCySiNtBu)TiCl2 (4) and (Cp*CySiNtBu)TiCl2 (5). The structures of the resulting cyclopentadienyl- (4b and 4c) and tetramethylcyclopentadienyl(silacycloalkyl)amidotitanium(IV) dichloride (5a, 5c, and 5d) species were studied by using X-ray crystallography to obtain geometrical information on cyclic silylene-modified CGCs. The ethylene polymerization by the cyclic silylene-bridged CGCs 4 and 5 was examined to verify the structure,catalytic activity relationship derived from variation of the size of a cyclic silylene ring. Indeed, the size of the cyclic silylene ring at the 1,1,-position of 4 and 5 affected the catalytic activities through the ethylene polymerization. Systematic increase in the catalytic activities was observed as the cyclic silylene-bridging unit was expanded from a four- to six-membered ring. In the present study, we found that CGCs of TiIV with a six-membered silylene-bridged ligand (5d) produced active catalytic species for the formation of polyethylene with Mw = 42.7,×,10,4 g,mol,1 and Mw/Mn = 2.1 with excellent catalytic activities (20.9 kg,polymer per mmol of Ti). When titanium(IV) dimethyl complex (6d) was applied in continuous polymerization process, impressive high catalytic activity on copolymerization with 1-octene was observed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] The N -Acylated Derivatives of Parent Complex [{(,-SCH2)2NH}Fe2(CO)6] as Active Site Models of Fe-Only Hydrogenases: Synthesis, Characterization, and Related PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2008Li-Cheng Song Abstract A series of N -acylated diiron azadithiolate complexes as H-cluster models was synthesized and structurally characterized. Treatment of parent complex [{(,-SCH2)2NH}Fe2(CO)6] (A) with 2-chloroacetic acid in the presence of dicyclohexylcarbodiimide or with 2-chloroacetyl chloride in the presence of Et3N gave N -chloroacetyl complex [{(,-SCH2)2NC(O)CH2Cl}Fe2(CO)6] (1). Further treatment of 1 with MeC(O)SK afforded N -acetylthioacetyl complex [{(,-SCH2)2NC(O)CH2SC(O)Me}Fe2(CO)6] (2). N -Ethoxylcarbonylacetyl complex [{(,-SCH2)2NC(O)CH2CO2Et}Fe2(CO)6] (3) and N-heterocyclic complexes [{(,-SCH2)2NC(O)C4H3Y-2}Fe2(CO)6] (4, Y = O; 5, Y = S) were produced by reactions of A with EtO2CCH2C(O)Cl, 2-furancarbonyl chloride, and 2-thiophenecarbonyl chloride in the presence of pyridine or Et3N. Similarly, N -malonyl complex [{Fe2(CO)6(,-SCH2)2NC(O)}2CH2] (6) and N -carbonylbenzaldehyde complex [{(,-SCH2)2NC(O)C6H4CHO- p}Fe2(CO)6] (7) could be obtained by reaction of A with malonyl dichloride in the presence of pyridine and with p -CHOC6H4C(O)Cl in the presence of Et3N. More interestingly, further reaction of 7 with PhCHO and pyrrole in a 1:3:4 molar ratio in the presence of BF3·OEt2 followed by p -chloranil yielded the first light-driven type of model complex containing an N -carbonylphenylporphyrin moiety [{(,-SCH2)2NC(O)(TPP)}Fe2(CO)6] (8, TPP = tetraphenylporphyrin group). Whereas the molecular structures of 2, 5, and 7 were established by X-ray crystallography, the electrochemical properties of 2,5 as well as the proton reduction to hydrogen gas catalyzed by 2 and 3 were studied by CV techniques.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis and Structure of Trialkyltantalum Complexes Stabilized by Aminopyridinato LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2006Awal Noor Abstract (4-Methylpyridin-2-yl)(trimethylsilyl)amine (1), (6-methylpyridin-2-yl)(trimethylsilyl)amine (2), and (2,6-diisopropylphenyl)(pyridin-2-yl)amine (3) were deprotonated and used as ligands to synthesize trialkyltantalum complexes. The reaction of 2 equiv. of 1 or 2 with pentabenzyltantalum afforded tribenzyltantalum(V) complexes by toluene elimination. Analogous reaction using 3 failed. Lithiation of 3 followed by the reaction with tribenzyltantalum dichloride gave rise to the corresponding tribenzyl complex. Other alkyltantalum complexes stabilized by this ligand environment can be prepared by treating tantalum pentachloride with 2 equiv. oflithiated 3 to form a bis(aminopyridinato)tantalum trichloride. The reaction of this trichloride with 3 equiv. of alkyllithium compounds like methyllithium affords the corresponding trialkyltantalum complexes. X-ray diffraction studies of four of the synthesized complexes were carried out. They adopt two different coordination environments, either slightly distorted capped octahedrons (sterically less demanding aminopyridinato ligands) or pentagonal bipyramids (bulkier aminopyridinato ligands). The alkyl species were surprisingly stable at elevated temperatures and no formation of mixed alkyl/alkylidene complexes was observed. Alkyl cation formation and the behaviour of a selection of these compounds in olefin polymerization were explored. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Bis(salicylaldiminato)titanium Complexes Containing Bulky Imine Substituents: Synthesis, Characterization and Ethene Polymerization StudiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2005Antti Pärssinen Abstract A series of titanium complexes bearing two anionic [N, O,] bidentate salicylaldiminato ligands, namely bis[(N -salicylidene)anilinato]titanium(IV) dichloride (1), bis[(N -salicylidene)-2,6-dimethylanilinato]titanium(IV) dichloride (2), bis[(N -salicylidene)-2,6-di- i - propylanilinato]titanium(IV) dichloride (3), bis[(N -salicylidene)-(1-naphthalenylimino)]titanium(IV) dichloride (4), bis[(N -salicylidene)-2,6-difluoroanilinato]titanium(IV) dichloride (5), and bis[(N -3-fluorosalicylidene)-2,6-difluoroanilinato]titanium(IV) dichloride (6) have been synthesized with good yields by a two-step procedure. The X-ray structure analysis reveals that in complex 2, titanium has a distorted octahedral coordination sphere in which the oxygen atoms and the chloride ligands form the basal plane. Both the chloride and the phenoxy moieties have a cis orientation and the angle between the chloride ligands is 93.05°. The imine nitrogen atoms complete the octahedral coordination of the Ti center by occupying the axial positions. The newly synthesized (2 and 4,6) and already known complexes (1 and 3) were introduced in detailed ethene-polymerization studies. The activities achieved were low to moderate depending on the size and nature of the imino substituents. The polyethenes (PEs) produced had high molar masses, and the modalities of the molecular weight distributions varyied with polymerization temperature. Based on the results of ab initio calculations and on the experimental data obtained, an explanation for uni- and bimodal polymerization behavior and the differences in catalytic activities are given. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthetic Explorations Towards Sterically Crowded 1,2,3-Substituted Bis(indenyl)zirconium(IV) DichloridesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2005Andreas C. Möller Abstract The systematic synthesis of 1,3-dialkyl-substituted 2-silylindenes and their suitability as zirconocene ligands is discussed. Unexpected reactivities rendered a number of substitution patterns unfeasible, especially for alkyl groups other than methyl in 2-(trimethylsilyl)indene derivatives, and essentially for all derivatives of 2-(dimethylsilyl)indene. The syntheses of rac/meso -bis[1-methyl-2-(trimethylsilyl)indenyl]zirconium(IV) dichloride (12) and bis[1,3-dimethyl-2-(trimethylsilyl)indenyl]zirconium(IV) dichloride (13b) are described. The solid-state structure of the latter displays strong deformations within the ligand framework and an unusually large Cpcentroid -Zr,Cpcentroid angle. Both, 12/MAO and 13b/MAO, displayed ethene and ethene-co-1-hexene polymerization activity. Curiously, 13b/MAO shows an extraordinary monomer selectivity, which can be rationalized by means of DFT calculations on the active site. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Unexpected Rearrangement Leading to Formation of a 1,3-Bis(triphenylphosphonio)prop-1-en-3-idyl CarboxylateEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2010R. Alan Aitken Abstract Whereas biphenyl-4,4,-dicarbonyl dichloride reacts with methylenetriphenylphosphorane to give the expected bis(acylylide) 1, the same reaction of biphenyl-2,2,-dicarbonyl dichloride results in a multistep rearrangement leading to the zwitterionic 2-[1,3-bis(triphenylphosphonio)prop-1-en-3-id-2-yl]biphenyl-2,-carboxylate 2. X-ray crystal structures of both 1 and 2 are reported. [source] Synthesis and Conformational Analysis of Tetrahydroisoquinoline-Fused 1,3,2-Oxazaphospholidines and 1,2,3-OxathiazolidinesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2008Ildikó Schuster Abstract The cyclizations of tetrahydroisoquinoline 1,2-amino alcohols with phenylphosphonic dichloride, bis(2-chloroethyl)phosphoramidic dichloride, thionyl chloride and sulfuryl chloride were utilized to synthesize 1,5,6,10b-tetrahydro-1,3,2-oxazaphospholo[4,3- a]isoquinolines (2, 3), 1,5,10,10a-tetrahydro-1,3,2-oxazaphospholo[3,4- b]isoquinolines (8, 9), 1,5,6,10b-tetrahydro-1,2,3-oxathiazolo[4,3- a]isoquinolines (4,6) anda 1,5,10,10a-tetrahydro-1,2,3-oxathiazolo[3,4- b]isoquinoline (11), which are the first representatives of these ring systems. NMR spectroscopic analysis revealed the existence of conformational equilibria that are fast on the NMR timescale. Theoretical DFT calculations pointed to the participation of generally two preferred conformers in the conformational equilibria; the positions of the equilibria were indicated by the experimental NMR spectroscopic parameters, and they are in good agreement with the theoretically calculated energy differences of the participating conformers. For two compounds, which could be not isolated (10, 12), both the preferred conformers and the stereochemistry could be concluded from the DFT calculation results. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Macrocyclic Cyclo[n]malonates , Synthetic Aspects and Observation of Columnar Arrangements by X-ray CrystallographyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2006Nikos Chronakis Abstract A variety of achiral and chiral macrocyclic oligomalonates were synthesised in a one-step procedure through condensation of malonyl dichloride with ,,,-diols. We have investigated the applicability of this method by varying the length and type of the spacers in the diol. Product distribution analysis revealed that the preferential formation of monomeric, dimeric, or trimeric macrocyclic malonates can be controlled by choosing diols with specific spacers connecting the hydroxy groups. Of special interest are the macrocyclic bismalonates, as they show pronounced crystallisability and arrange into columnar motifs in the solid state. They feature distinctive dihedral angles: all ester moieties adopt anti conformations whereas the planes of the carboxy moieties of each malonate residue arrange in an approximately orthogonal fashion. The latter geometry is enforced by the macrocyclic structures, as revealed by a conformational search in the Cambridge Structural Database. The X-ray diffraction data show that C=O···H,C, and C,O···H,C hydrogen bonds stabilise the columnar arrangement of the dimeric rings with formation of tubular assemblies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] The Extraordinary Cocatalytic Action of Polymethylaluminoxane (MAO) in the Polymerization of Terminal Olefins by Metallocenes: Chemical Change in the Group 4 Metallocene Dimethyl Derivatives Induced by MAO,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2005John J. Eisch Abstract In the polymerization of olefins with Group 4 metallocene dichlorides or dimethyl derivatives as procatalysts the use of polymethylaluminoxane (MAO) as the cocatalyst, especially in extreme excess (102,103 times the metallocene equivalent), has been shown to have an extraordinary accelerating effect on the rate of olefin polymerization, when compared with the cocatalytic action of alkylaluminum halides. In attempts at explaining the greatly superior catalytic activity of MAO in olefin polymerization (the MAO conundrum), hypotheses have generally paralleled the steps involved in the cocatalytic action of RnAlCl3,n, namely the alkylation of Cp2MtCl2, ionization of Cp2Mt(R)Cl into the metallocenium cation, [Cp2Mt,R]+, and anion, [Rn,1AlCl4,n], and subsequent ion-pair separation. In order to understand any differences in catalytic action between such cocatalysts, we have studied the individual action of MAO (100 equiv.) and of MeAlCl2 (1,2 equiv.) on each of the Group 4 metallocene derivatives, Cp2TiCl2, Cp2ZrCl2, Cp2Ti(CH3)2 and Cp2Zr(CH3)2. With MeAlCl2 each of the metallocene derivatives appeared to form the cation, [Cp2Mt,CH3]+, with greater (Ti) or lesser (Zr) ease, because an alkyne such as diphenylacetylene was then found to insert into the Mt,CH3 bond stereoselectively. In striking contrast, treatment of each metallocene with MAO gave two reactions very different from MeAlCl2, namely a steady evolution of methane gas upon mixing and a finding upon hydrolytic workup that the diphenylacetylene present had undergone no insertion into the Mt,CH3 bond but instead had been reductively dimerized completely to (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene. To account for this astonishing difference in chemical behavior between MAO and MeAlCl2 in their cocatalytic activation of Group 4 metallocenes to olefin polymerization, it is necessary to postulate a novel, unique sequence of reaction steps occurring between MAO and the metallocene. If one starts with the metallocene dichloride, then the free TMA present in the MAO would generate the Cp2Mt(CH3)2. This metallocene dimethyl derivative, complexed with an oligomeric MAO unit, would undergo a transfer-epimetallation with added olefin or acetylene to form a metallacyclopropane or metallacyclopropene, respectively. With added diphenylacetylene the resulting 2,3-diphenylmetallacyclopropene would be expected rapidly to insert a second alkyne to form the 2,3,4,5-tetraphenyl-1-metallacyclopentadiene. Simple hydrolysis of the latter intermediate would generate (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene while alternative workup with D2O would give the 1,4-dideuterio derivative of this butadiene. Both such expectations were confirmed by experiment. In the case of added olefin, similar metallacyclopropane and metallacyclopentane intermediates should be produced until ring opening of the latter five-membered ring leads to an open-chain zwitterion, a process having ample precedent in the research of Gerhard Erker. The solution to the MAO conundrum then, namely the extraordinary cocatalytic activity of MAO in olefin polymerization by metallocenes, lies in the unique catalytic activation of the Group 4 metallocene dimethyl derivative, which occurs by transfer-epimetallation of the olefin monomer by the Cp2Mt(CH3)2,MAO complex. The most advantageous Lewis acidic sites in the MAO,oligomeric mixture for such metallocene,MAO complexation are suggested to be terminal Me2Al,O,AlMe, segments of an open-chain oligomer. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] A new bridge in [2.2]cyclophanes: The addition of Se2Cl2 to pseudogeminally substituted bispropargylic alcoholsHETEROATOM CHEMISTRY, Issue 3 2010M. Lucian Birsa The regio- and stereo-specific addition of monoselenium monochloride to pseudogeminally substituted bispropargylic alcohols has been performed under high dilution conditions. The disproportionation reaction of selenium monochloride to selenium dichloride and triselenium dichloride leads to the corresponding divinylic mono- and tri-selenides. The stereochemistry of the newly generated double bond was assigned as Z by 2D NMR experiments. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:126,130, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20586 [source] Synthesis and conformational study of P -heterocyclic androst-5-ene derivativesHETEROATOM CHEMISTRY, Issue 1 2008Éva Frank The reactions of (20R)-3,-acetoxy-21-hydroxymethylpregn-5-en-20-ol (2) and (20R)-3,-acetoxypregn-5-ene-20,21-diol (11) with phenylphosphonic dichloride 3 and aryl dichlorophosphates 4,6 afforded novel types of P -heterocyclic androst-5-ene derivatives 7,10 and 12 as epimeric pairs. The diastereomers were separated by column chromatography and were characterized by NMR spectroscopy. Estimation of the stereostructures of the corresponding epimers by B3LYP/631G(d) DFT ab initio calculations suggested that the six-membered hetero ring in compounds 7b and 8a,10a adopts predominantly a chair conformation, with the P -substituents in their preferred orientation. The cyclic phosphonate moiety in 7a or 8b,10b, however, seems to exist as an equilibrium mixture of chair,distorted- boat or chair,chair forms. The theoretical calculations indicate that the conformational equilibrium is shifted toward the distorted- boat conformer for 7a, with a pseudoequatorial P -phenyl substituent, whereas for 8b,10b the chair conformer with an equatorial P -phenoxy group predominates. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:7,14, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20372 [source] Mechanism of interaction of DNA bases with dichloro-[1-alkyl-2-(naphthylazo)imidazole]palladium(II) complexes: A cytosine caseINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 7 2009Pradip Kumar Ghosh Interaction of cytosine (C) with dichloro-[1-alkyl-2-(,-naphthylazo)imidazole]-palladium(II) [Pd(,-NaiR)Cl2, 1] and dichloro-[1-alkyl-2-(,-naphthylazo)imidazole]-palladium(II) [Pd(,-NaiR)Cl2, 2] complexes {where alkyl R = Me (a), Et (b) or Bz (c)} in acetonitrile (MeCN)-water (50% v/v) medium to yield [{1-alkyl-2-(,-naphthylazo)-imidazole}bis(cytosine)]palladium(II)dichloride (3a, 3b, 3c) and [{1-alkyl-2-(,-naphthylazo)-imidazole}bis(cytosine)]palladium(II)dichloride (4a, 4b, 4c) was studied. The products were characterized by microanalytical data and spectroscopic techniques (FT-IR, UV,vis, and NMR). The reaction kinetics show first-order dependence of the rate on each of the concentration of Pd(II) complex and C. External addition of Cl, ion (LiCl) did not influence this nucleophilic substitution rate process and has proved the cleavage of first PdCl bond is the rate-determining step. Thermodynamic parameters standard enthalpy of activation (,,Ho) and standard entropy of activation (,,So) were determined from variable temperature kinetic studies. The negative values of ,,So indicate that the reaction proceeds through an associative inner sphere mechanism. The magnitude of the second-order rate constant k2 increases in the following order: Pd(NaiEt)Cl2 (b) < Pd(NaiMe)Cl2 (a) < Pd(NaiBz)Cl2 (c) as well as Pd(,-NaiR)Cl2 (1) < Pd(,-NaiR)Cl2 (2), which corroborates with the experimental ,,Ho values. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 463,472, 2009 [source] Highly Efficient Ligands for the Palladium-Assisted Double N -Arylation of Primary Amines for One-Sep Construction of CarbazolesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2010Yibo Zhou Abstract A highly efficient one-pot synthesis of carbazoles via palladium-catalyzed double N -arylation of primary amines with 2,2,-dihalobiphenyls is described using a catalyst system comprised of tris(dibenzylideneacetone)dipalladium(0) (Pd2dba3) and the proazaphosphatrane P(i -BuNCH2CH2)3N (8) or its derivative (t- Bu)2PNP(i- BuNCH2CH2)3N (9a) as the ligand. The process is effective for double N -arylation of 2,2,-biphenyl dibromide, diiodide, and even dichloride with a variety of primary amines including neutral, electron-rich, electron-deficient, and sterically hindered anilines as well as aliphatic amines. [source] One-Pot Synthesis of Carbamoyl Azides Directly from Primary Alcohols and Oxidation of Secondary Alcohols to Ketones Using Iodobenzene Dichloride in Combination with Sodium AzideADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Xiao-Qiang Li Abstract An effective synthesis of carbamoyl azides directly from primary alcohols using iodobenzene dichloride in combination with sodium azide has been developed. Moreover, the same regent combination was also efficient for the oxidation of secondary alcohols to the corresponding ketones. [source] Highly Stereoselective Halocyclopropanation of ,,,-Unsaturated AmidesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Abstract A convenient highly stereoselective synthesis of chloro- and bromocyclopropanamides from di- tri- or tetrasubstituted (E)- or (Z)-,,, - unsaturated amides with total or high stereoselectivity promoted by chromium dichloride or dibromide is described. The transformation of chlorocyclopropanamides into the corresponding ketones or amines is also reported. A mechanism to explain these transformations is proposed. [source] Donor-Stabilized Phosphenium Adducts as New Efficient and Immobilizing Ligands in Palladium-Catalyzed Alkynylation and Platinum-Catalyzed Hydrogenation in Ionic LiquidsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009Samer Saleh Abstract The straightforward synthesis of a new donor-stabilized phosphenium ligand 3d by addition of bromodifurylphosphine to 1,3-dimethylimidazolium-2-carboxylate 1 is described. The obtained ligand exhibits a very strong ,-acceptor character, comparable to that of triphenyl phosphite [P(OPh)3] or of tris-halogenophosphines, with a ,CO(A1) at 2087,cm,1 for its nickel tricarbonyl complex. This ligand, as well as the related 3a which was obtained from chlorodiphenylphosphine, were tested in palladium-catalyzed aryl alkynylation and in the platinum-catalyzed selective hydrogenation of chloronitrobenzenes, both in an ionic liquid phase. In CC bond cross-coupling we observed that the increase of the ,-acceptor character in ligand 3d, due to the introduction of an additional electron-withdrawing group, provides a very efficient catalyst in the alkynylation reaction of aryl bromides with phenylacetylene, including the deactivated 4-bromoanisole or the sterically hindered 2-bromonaphthalene. The catalytic activity decreases with recycling due to the sensitiveness of ligands to protonation in the ionic phase. Conversely, a multiple recycling of the metal/ligand system in non-acidic media was achieved from platinum-catalyzed hydrogenation of m- chloronitrobenzene. The catalytic results obtained by employing the complex of platinum(II) chloride with 3a [trans -PtCl2(3a)2] in comparison with the non-ionic related trans -tris(triphenylphosphine)platinum dichloride [trans -PtCl2(PPh3)2] complex clearly indicate that the simultaneous existence of a strong ,-acceptor character and a positive charge within the ligand 3a significantly increases the life-time of the platinum catalyst. The selectivity of the reaction is also improved by decreasing the undesirable formation of dehalogenation products. This cationic platinum complex trans -PtCl2(3a)2 is the first example of a highly selective catalyst for hydrogenation of chloronitroarenes immobilized in an ionic liquid phase. The system was recycled six times without noticeable metal leaching in the organic phase, and no loss of activity. [source] Selective Oxidative Ligand Coupling of Organoborates Bearing an Alkynyl GroupADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009Toru Amaya Abstract Selective oxidative ligand coupling of alkynyl(triaryl)borates was achieved by treatment with ethoxyvanadyl dichloride [VO(OEt)Cl2] to form the spsp2 carbon-carbon bond. A one-pot procedure through the in situ preparation of the borate was demonstrated using triphenylborane and 1-ethynyl-4-methoxybenzene. [source] Highly Convenient, Clean, Fast, and Reliable Sonogashira Coupling Reactions Promoted by Aminophosphine-Based Pincer Complexes of Palladium Performed under Additive- and Amine-Free Reaction ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009Jeanne Abstract Sequential addition of 1,1,,1,,-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to toluene solutions of (cyclooctadiene)palladium dichloride [Pd(cod)(Cl)2] under nitrogen in "one pot" almost quantitatively yielded the aminophosphine-based pincer complexes {[C6H3 -2,6-(XP{piperidinyl}2)2]Pd(Cl)} (X=NH 1; X=O 2). Complex 1 (and to a minor extent 2) proved to be efficient Sonogashira catalysts, which allow the quantitative coupling of various electronically deactivated and/or sterically hindered and functionalized aryl iodides and aryl bromides with several alkynes as coupling partners within very short reaction times and low catalyst loadings. Importantly, in contrast to most of the Sonogashira catalysts, which either are both air- and moisture-sensitive and/or require the addition of co-catalysts, such as copper(I) iodide [CuI], for example, or a large excess of an amine, the coupling reactions were carried out without the use of amines, co-catalysts or other aditives and without exclusion of air and moisture. Moreover, the desired products were exclusively formed (no side-products were detected) without employing an excess of one of the substrates. Ethylene glycol and potassium phosphate (K3PO4) were found to be the ideal solvent and base for this transformation. Experimental observations strongly indicate that palladium nanoparticles are not the catalytically active form of 1 and 2. On the other hand, their transformation into another homogeneous catalytically active species cannot be excluded. [source] From Mono-Triazolium Salt to Bis-Triazolium Salt: Improvement of the Asymmetric Intermolecular Benzoin CondensationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2008Yajun Ma Abstract A solution to the long-standing challenge of developing a highly effective method for the enantioselective intermolecular benzoin condensation of aromatic aldehydes is described. The chiral bis-bicyclic triazolium salt , 1,3-bis{(S)-5-benzyl-6,8-dihydro-5H -[1,4]oxazino[2,1- c][1,2,4]triazol-2-ium-2-yl}benzene dichloride [(S)- 5a-1] is currently the most efficient precatalyst for the asymmetric variant of the benzoin condensation. [source] Ethylene/,-olefin copolymerization using diphenylcyclopentadienyl-phenoxytitanium dichloride/Al(iBu)3/[Ph3C][B(C6F5)4] catalyst systemsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Hongchun Li Abstract Copolymerization of ethylene with 1-octene and 1-octadecene using constrained geometry catalysts 2-(3,4-diphenylcyclopentadienyl)-4,6-di- tert -butylphenoxytitanium dichloride (1), 2-(3,4-diphenylcyclopentadienyl)-6- tert -butylphenoxytitanium dichloride (2), 2-(3,4-diphenylcyclopentadienyl)-6-methylphenoxytitanium dichloride (3), and 2-(3,4-diphenylcyclopentadienyl)-6-phenylphenoxytitanium dichloride (4) was studied in the presence of Al(iBu)3 and [Ph3C][B(C6F5)4](TIBA/B). The effect of the catalyst structure, comonomer, and reaction conditions on the catalytic activity, comonomer incorporation, and molecular weight of the produced copolymers was also examined. The 1/TIBA/B catalyst system exhibits high catalytic activity and produces high molecular weight copolymers. The melting temperature and the degree of crystallinity of the copolymers show a decrease with the increase in the comonomer incorporation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis of sitting-atop type adducts of diphenyl and dimethyltin(IV) dihalides with meso -tetraarylporphyrinsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2006Abedien Zabardasti Some molecular adducts of dimethyltin(IV) dichloride, diphenyltin(IV) dichloride and diphenyltin(IV) dibromide with para -substituted meso -tetraphenylporphyrin have been prepared. This adducts with general formula [(Me2SnCl2)2H2T(4-X)PP], [(Ph2SnCl2)2H2T(4-X)PP], and [(Ph2SnBr2)2H2T(4-X)PP]; {X= CH3O, CH3, H, and Cl} have been synthesized and characterized by means of 1H NMR, UV-Vis, and elemental microanalysis methods. [source] | |||||||||||||||||||||||||||||||