PhI(OAc)2 and BF3–OEt2 mediated heterocyclization: metal-free synthesis of pyrimidine-annulated oxazolines

A simple high yielding and highly efficient synthesis of oxazoline ring fused with uracil moiety is reported. Hypervalent iodine (PIDA) in the presence of BF₃–OEt₂ generates an effective electrophile to activate uracil C5–C6 double bond leading to heterocyclization.     

FeCl3催化Et2Zn与芳香醛的加成反应研究

以FeCl_3作为催化剂, 研究了Et_2Zn与芳香醛的加成反应, 考察了催化剂、溶剂、催化剂与Et_2Zn用量及温度对该反应的影响. 实验结果表明: 在60℃, 1.2当量Et_2Zn, 甲基环戊基醚为溶剂的反应条件下, 10 mol% FeCl_3可以较高效的将各种芳香醛转化为仲醇.     

Highly Efficient, Four Component, One-pot Synthesis of Tetrasubstituted Imidazoles Using a Catalytic Amount of FeCl3 · 6H2O

An efficient and improved procedure for the synthesis of tetrasubstituted imidazoles by FeCl₃ · 6H₂O catalyzed four-component one-pot synthesis in refluxing ethanol is described.     

Disulfido iron-manganese carbonyl cluster complexes: Synthesis, structure, bonding and properties of the radical CpFeMn2(CO)7(μ3-S2)2

Two new compounds CpFeMn₂(CO)₇(μ₃-S₂)₂ (2) and Cp₃Fe₃Mn(CO)₄(μ₃-S₂)₂(μ₃-S) (3) were obtained by the treatment of [CpFeMn(CO)₅(μ₃-S₂)]₂ (1) with CO at room temperature in the presence of room light. Compound 2 contains two triply bridging disulfido ligands on opposite sides of an open FeMn₂ triangular cluster. EPR and temperature-dependent magnetic susceptibility measurements show that it is paramagnetic with one unpaired electron per formula equivalent. The electronic structure of 2 was established by DFT and Fenske-Hall (FH) molecular orbital calculations which show that the unpaired electron occupies a low lying antibonding orbital that is located principally on the iron atom. The cyclic voltammogram of 2 exhibits one reversible one-electron oxidation wave at +0.34 V and one irreversible one-electron reduction wave at −0.66 V vs. Ag/AgCl. Compound 3 contains three iron atoms and one manganese atom with two triply bridging disulfido ligands and one triply bridging sulfido ligand and has no unpaired electrons. The molecular structures of compounds 2 and 3 were established by single crystal X-ray diffraction analyses.     

Synthesis of Silica@α-Fe2O3 nanospheres by surface-initiated ATRP

We reported a new method to prepare Silica@α-Fe₂O₃ nanospheres by surface-initiated atom transfer radical polymerization (ATRP). Firstly, polymerizable surfactants-modified α-Fe₂O₃ nanoparticles were prepared in water-toluene microemulsion. Then, as-synthesized α-Fe₂O₃ nanoparticles acted as the macro-monomer of surface-initiated ATRP on silica nanospheres to make target product. Morphological characterization of the product was performed using transmission electron microscopy (TEM). Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance UV-vis spectroscopy were used to verify the incorporation of α-Fe₂O₃ nanoparticles on silica nanosphere.     

Kinetics of the radical reactions in pulse radiolyzed RHF — CO2(SF6)-O2-NO gaseous mixtures; RHF = CH3CH2F, CH3CHF2, CH3CF3, CH2FCF3

The kinetics of the peroxy radicals RHFO₂ reactions with NO has been studied by using pulse radiolysis and UV absorption spectroscopy. The rate constants of interaction of oxygen atoms with NO − k ₂ = 2.2±0.2·10⁻¹² cm³·s⁻¹ and NO₂ − k ₃ = 2.1±0.2·10⁻¹¹ cm³·s⁻¹ were found in agreement with the literature values. The bath gases (SF₆ or CO₂) have got minor effect on the rate constants of RHFO₂+NO→NO₂+prod. reactions; RHFO₂ = CH₃CH₂O₂, CH₃CHFO₂, CH₃CF₂O₂, CF₃CH₂O₂, CF₃CHFO₂. The obtained rate coefficients are in the scope of the literature values, although they are lower than those recommended in NIST database. The reasons are discussed.     

FeCl3 catalyzed sp C–H amination: synthesis of aminals with arylamines and amides

A simple and efficient amination of sp³ C–H bonds adjacent to a nitrogen atom in amides was introduced. The reaction was catalyzed by cheap and low toxic iron salt and used arylamines as nitrogen source. It provides a straightforward construction of acyclic aminals under mild conditions.     

Synthesis and characterization of P2O5–ZrO2–SiO2 membranes doped with tungstophosphoric acid (PWA) for applications in PEMFC

Homogeneous, transparent and crack-free P₂O₅–ZrO₂ and P₂O₅–ZrO₂–SiO₂ membranes have been synthesized by the sol–gel process. A first step has been oriented to the optimization of the synthesis and characterization of different compositions by TGA, FE-SEM, FTIR and EIS to choose the best inorganic composition in terms of chemical and mechanical stability, and proton conductivity. The addition of SiO₂ improves the mechanical and chemical stability. On the other hand, compositions with higher content in P₂O₅ have demonstrated lower mechanical and chemical stability against water, but higher proton conductivity. The water retention and high porosity of inorganic membranes leads to high proton conductivity, 10⁻² S/cm, at 140 °C and 100% relative humidity. The second step has been focused in the study of doped inorganic membranes of molar composition 99.65(40P₂O₅–20ZrO₂–40SiO₂)–0.35PWA. The high homogeneity, transparency and SEM-EDX analysis of these membranes indicates no phase separation suggesting that PWA is well dispersed in the inorganic structure. The incorporation of PWA in sol–gel oxides provides an increase of the proton conductivity at low relative humidity due to the adequate distribution of PWA in the inorganic network. Conductivity increases in two orders of magnitude at low humidity (10⁻⁴ S/cm at 50 °C and 62% RH) compared with undoped sol–gel oxide membranes.     

Synthesis and crystal structure of [W3S4(Acac)3(PPh3)3]PF6 · 0.5CHCl3 and [W3S4(Hfac)3(PPh3)2Br] · 2CHCl3

New cluster complexes [W₃S₄(Acac)₃(PPh₃)₃]PF₆ · 0.5CHCl₃ (Acac = CH₃C(O)CHC(O)CH₃) (I) and [W₃S₄(Hfac)₃(PPh₃)₂Br] · 2CHCl₃ (Hfac = CF₃C(O)CHC(O)CF₃) (II) were synthesized. Their molecular and crystal structures were determined by X-ray diffraction. The cis-cis type of coordination of acetylacetonate and hexafluoroacetylacetonate ligands in I and II, respectively, was established, and the PPh₃ ligands were found in the trans-positions with respect to the “capping” sulfide ligand (μ³-S).     

DME Synthesis From CO/H2 over Cu-Mn/?-Al2O3 Catalyst

A γ-alumina-supported copper-manganese oxide catalyst prepared by an impregnation method was used for DME synthesis from CO/H₂ (syngas). The Cu-Mn/γ-Al₂O₃ catalyst exhibits high catalytic activity in CO hydrogenation. The effect of the loading amount of Cu, the ratio of n(Cu)/n(Mn) and the reaction conditions on the activity and selectivity to dimethyl ether (DME) from CO/H₂ (syngas) were investigated. The activity was found to increase with increasing surface area of metallic copper to some extent, but it is not a linear relationship. This indicated that the catalytic activity depends on both the metallic copper area and the synergy between the copper and manganese oxide. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis of β-peroxy-lactones using 30% H2O2

Cyclopropyl carbinols 1a-e react with H₂O₂ in the presence of concd H₂SO₄ at 0-5 °C to furnish the corresponding hydroperoxides 2a-e in 45-82% yields. This efficient trapping of cyclopropylmethyl cations by the hydroperoxy group has been exploited to prepare compounds 14-23, a new series of cyclopropyl substituted β-peroxy-lactones.     

Kinetics of Synthesis of Ba1.0Co0.7Fe0.2Nb0.1O3-δ through Solid-Solid Reaction

The mechanism of solid-solid reaction between BaCO₃ and Co₃O₄/Fe₂O₃/Nb₂O₅ has been investigated by means of non-isothermal thermogravimetry and differential scanning calorimetry (DSC) under flowing air gas conditions at atmospheric pressure with a new solid-solid reaction model. The effects of high speed agitating mixing and ball-milling mixing processes on the synthesis kinetics were also studied. The synthesis kinetics of Ba_1.0Co_0.7Fe_0.2Nb_0.1O_3-δ from the BaCO₃ and Co₃O₄/Fe₂O₃/Nb₂O₅ particles was calculated by applying the modified model. The results indicated that the overall reaction process was considered involving two stages: addition reaction between BaCO₃ and Co₃O₄/Fe₂O₃/Nb₂O₅ particles in the first stage and solution reaction between BaCoO₃, BaFeO₃, and BaNbO₃ to form a homogeneous Ba_1.0Co_0.7Fe_0.2Nb_0.1O_3-δ phase in the second stage. The new model matched well with the experimental data. The apparent activation energy of addition reaction stage of the high speed agitating mixing sample was estimated to be 376.76 kJ·mol⁻¹, which was only 3/4 of that of the ball-milling mixing sample (494.76 kJ·mol⁻¹). These results indicated that the high-speed agitating process could enhance atomic diffusion and facilitate the subsequent reaction, thus it is believed as a more effective, energy saving, and environmentally benign mixing process.     

Molecular and crystal structures of [FeCl(HMPA)3(H2O)2]2+(FeCl4) 2? · 3HMPA

IR and single-crystal X-ray diffraction study are carried out for compound, C₃₆H₁₁₂Cl₉Fe₃N₁₈O₈P₆(I). It crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 14.2992(3), b = 21.4351(4), c = 25.5407(5) ?, V = 7828.3(3) ?³, ρ_calcd = 1.553 g/cm³, Z = 4. The FeCl fragment is coordinated with chlorine atom of two water molecules and three HMPA molecules to form a cation, with a distorted octahedral coordinate geometry. In the crystal I, the cation is linked with HMPA by the O-H…O hydrogen bond. The chiral crystal is formed through self-assembly even from achiral molecules.     

Crystal structure of K2[Mo3(PdPPh3)S4(C2O4)3(H2O)3]·0.5H2O

By the reaction of [Mo₃S₄(C₂O₄)₃(H₂O)₃]²⁻ with PdCl₂ and NH₄H₂PO₂ as a reducing agent, followed by the addition of PPh₃, a new oxalate cuboidal cluster complex [Mo₃(PdPPh₃)S₄(C₂O₄)₃(H₂O)₃]²⁻ is obtained. It was isolated and structurally characterized as K₂[Mo₃(PdPPh₃)S₄(C₂O₄)₃(H₂O)₃]·0.5H₂O. Original Russian Text Copyright ? 2008 by A. L. Gushchin, M. N. Sokolov, D. Yu. Naumov, and V. P. Fedin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 4, pp. 775–778, May–June, 2008.     

Iodine-catalyzed efficient synthesis of azaarene substituted 3-hydroxy-2-oxindole derivatives through sp3 C–H functionalization

Iodine-catalyzed benzylic sp³ C–H bond functionalization of lutidines or picolines to isatins is described. This synthetic method provides a rapid entry towards biologically interesting 3-azaarene substituted 3-hydroxy-2-oxindole derivatives.     

Synthesis and Crystal Structure of the π-Complex 5CuCl?Si(O–CH2–CH=CH2)4

This paper discusses the results of synthesis and X-ray diffraction analysis (DARCH single crystal diffractometer, MoK radiation) of a -complex of copper(I) chloride with tetraallyloxysilane 5CuClSi(O–CH₂–CH=CH₂)₄ (space group P4/n, a = 13.813(2), c = 5.9424(7) , Z = 2). Structural data for other olefin complexes of copper(I) are used to analyze the structural effect of the restricted disordering of the guest molecule with conservation of the high general symmetry of the structure introduced by the olefin molecule.     

FeCl3·6H2O-catalyzed selective conjugate reduction of alkylidene-β-keto esters and alkylidene-1,3-diketones

FeCl₃·6H₂O/triethylsilane composite catalyst system is successfully developed for the selective conjugate reduction of carbon-carbon double bond of Michael acceptor-alkylidene-β-keto esters and alkylidene-1,3-diketones under mild reaction conditions to afford the corresponding saturated β-keto esters and 1,3-diketones. The process involves the iron-catalyzed hydrosilylation, followed by in situ hydrolysis of silyl enol ether. The optimal reaction conditions include 20?mol% of FeCl₃·6H₂O and triethylsilane in dichloromethane at room temperature. A broad range of substrates undergoes the reduction in 1, 4-selective manner to afford the corresponding saturated compounds in excellent yields.     

α-Phenylselenenylation of aldehydes and ketones with diphenyl diselenide mediated by KF/Al2O3

The utility of KF/Al₂O₃ for the synthesis of α-phenylseleno aldehydes and ketones from the corresponding aldehydes or ketones and diphenyl diselenide has been investigated. Simple stirring of a mixture of aldehyde or ketone and diphenyl diselenide in the presence of KF/Al₂O₃ at room temperature selectively produces the corresponding α-phenylseleno aldehyde or ketone in good to excellent yields.     

Synthesis and crystal structure of [Mo3S4(Dppen)3Cl3]PF6 · 1.5CH2Cl2 and [W3S4(Dppe)3Br3]2ZnBr4 · 5.5CH3CN

New cluster complexes [Mo₃S₄(Dppen)₃Cl₃]PF₆ · 1.5CH₂Cl₂ (Dppen = cis-Ph₂PCH=CHPPh₂) (I) and [W₃S₄(Dppe)₃Br₃]₂(ZnBr₄)₂ · 5.5CH₃CN (Dppe = Ph₂PCH₂CH₂PPh₂) (II) were synthesized. Their molecular and crystal structures were determined by X-ray diffraction. Diphoshine ligands in the complexes I and II are coordinated in the bidentate mode, providing an arrangement of three chelate rings, giving rise to chirality.