HClO4-SiO2 catalyzed stereoselective synthesis of β-amino ketones via a direct Mannich-type reaction

The HClO₄-SiO₂ catalyzed three-component, one-pot Mannich reaction of ketones, aromatic aldehydes and aromatic amines is carried out in ethanol to afford the corresponding β-amino ketones in good yields and high stereoselectivities in favor of the anti-isomer. Three new compounds are reported.     

Trifluoromethylation of various aromatic compounds by CF3I in the presence of Fe(II) compound, H2O2 and dimethylsulfoxide

Trifluoromethylation of aromatic and hetero-aromatic compounds by CF₃I in the presence of Fe(II) compound, H₂O₂ and dimethylsulfoxide was investigated. Various trifluoromethylated benzene derivatives, six-membered nitrogen-containing aromatic compounds and five-membered hetero-aromatic compounds were obtained under mild conditions. General orientation of electrophilic substitution of aromatic compounds was observed similarly as reported in other radical trifluoromethylation previously.     

Alignment of acentric MoO3F3 anions in a polar material: (Ag3MoO3F3)(Ag3MoO4)Cl

(Ag₃MoO₃F₃)(Ag₃MoO₄)Cl was synthesized by hydro(solvato)thermal methods and characterized by single-crystal X-ray diffraction (P3m1, No. 156, Z=1, a=7.4488(6)Å, c=5.9190(7) Å). The transparent colorless crystals are comprised of chains of distorted fac-MoO₃F₃³⁻ octahedra and MoO₄²⁻ tetrahedra anions, as suggested by the formulas Ag₃MoO₃F₃ and Ag₃MoO₄⁺, and are connected through Ag⁺ cations in a polar alignment along the c-axis. One Cl⁻ anion per formula unit serves as a charge balance and connects the two types of chains in a staggered fashion, offset by . In MoO₄²⁻, the Mo atom displaces towards a single oxide vertex, and in MoO₃F₃³⁻, the Mo displaces towards the three oxide ligands. The ordered oxide-fluoride ligands on the MoO₃F₃³⁻ anion is important to prevent local inversion centers, while the polar organization is directed by the Cl⁻ anion and interchain dipole-dipole interactions. The dipole moments of MoO₃F₃³⁻ and MoO₄²⁻ align in the negative c-axis direction, to give a polar structure with no cancellation of the individual moments. The direction and magnitude of the dipole moments for MoO₃F₃³⁻ and MoO₄²⁻ were calculated from bond valence analyses and are 6.1 and 1.9 debye (10⁻¹⁸ esu cm) respectively, compared to 4.4 debye for polar NbO₆ octahedra in LiNbO₃, and 4.5 debye for polar TiO₆ octahedra in KTiOPO₄ (KTP).     

Intramolecular construction of trifluoromethyl group by the palladium-catalyzed reaction of 2,3,3-trifluoroallylic carbonates with O-nucleophiles

The synthesis of the trifluoromethyl group containing enol ethers by the palladium-catalyzed intermolecular reaction of 2,3,3-trifluoroallylic carbonates with oxygen nucleophiles was accomplished. The reaction proceeds through the intermolecular attack of oxygen nucleophiles on the C-2 carbon atom of the allylic unit, and the intramolecular fluorine atom shift from the C-2 position to the C-3 position. The reactions with several types of alcohols and phenols proceeded smoothly, and afforded the corresponding trifluoromethyl group containing enol ethers in good to high yields.     

Pre-evaluation of metal ions as a catalyst on chemiluminometric sequential injection analysis with luminol-H2O2 system

Catalytic effect of metal ions on luminol chemiluminescence (CL) was investigated by sequential injection analysis (SIA). The SIA system was set up with two solenoid micropumps, an eight-port selection valve, and a photosensor module with a fountain-type chemiluminescence cell. The SIA system was controlled and the CL signals were collected by a LabVIEW program. Aqueous solutions of luminol, H₂O₂, and a sample solution containing metal ion were sequentially aspirated to the holding coil, and the zones were immediately propelled to the detection cell. After optimizing the parameters using 1 × 10⁻⁵ M Fe³⁺ solution, catalytic effect of some metal species was compared. Among 16 metal species examined, relatively strong CL responses were obtained with Fe³⁺, Fe²⁺, VO²⁺, VO₃⁻, MnO₄⁻, Co²⁺, and Cu²⁺. The limits of detection by the present SIA system were comparable to FIA systems. Permanganate ion showed the highest CL sensitivity among the metal species examined; the calibration graph for MnO₄⁻ was linear at the concentration level of 10⁻⁸ M and the limit of detection for MnO₄⁻ was 4.0 × 10⁻¹⁰ M (S/N = 3).     

1,3-Diynes synthesis by homo-coupling of terminal alkynes using a Pd(PPh3)4/Ag2O simple catalyst system

Amine- and copper salt-free palladium-catalyzed homo-coupling reaction of terminal alkynes proceeded efficiently in the presence of silver(I) oxide, which served as both activator and oxidant, in tetrahydrofuran at 60 °C to achieve satisfactory yields of 1,3-diyne compounds. It was demonstrated for the first time by means of XPS analysis that Pd(0) species can be oxidated to Pd(II) by silver(I) oxide.     

Synthesis of dihydrofurans containing trifluoromethyl ketone and heterocycles by radical cyclization of fluorinated 1,3-dicarbonyl compounds with 2-thienyl and 2-furyl substituted alkenes

Manganese(III) acetate based radical cyclization of various fluorinated 1,3-dicarbonyl compounds with 2-thienyl and 2-furyl substituted alkenes produced 3-trifluoroacetyl and 2-trifluoromethyl-dihydrofurans in good yields. The radical cyclizations of 2-methyl-5-[(E)-2-phenylvinyl]furan 2b and 2-[(E)-2-phenylvinyl]thiophene 2c led to the formations of 5-(5-methyl-2-furyl)-4,5-dihydrofuran and 5-(2-thienyl)-4,5-dihydrofuran, respectively. In the reactions of 1,3-dicarbonyls with alkenes, 2-thienyl substituted alkenes formed 4,5-dihydrofurans in higher yields than 2-furyl substituted alkenes.     

Ag3PO4/Ag2S/g-C3N4复合光催化剂的制备与性能

通过沉积法和离子交换法成功地制备了Ag_3PO_4/Ag_2S/g-C_3N_4复合型光催化剂。利用X射线多晶粉末衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、N_2吸附-脱附等温线、紫外-可见漫反射光谱、荧光光谱等手段对样品进行了表征。通过降解罗丹明B考察其可见光催化活性及稳定性,研究了硫化钠与磷酸银物质的量的比值(n_(Na_2S)/n_(Ag_3PO_4))、g-C_3N_4添加量对所制备复合光催化材料性能的影响,同时对光催化机理进行了探讨。结果表明,随着n_(Na2S)/n_(Ag3PO4)的增加,所得复合催化材料活性先增加后降低;当n_(Na2S)/n_(Ag_3PO_4)为1.5%、g-C_3N_4与Ag_3PO_4的质量比为3∶7时制备的催化剂ASC1.5的光催化活性最好,在可见光照射下,40 min内可将罗丹明B完全降解,且5次循环使用后仍保持较高的催化活性。和Ag_3PO_4相比,Ag_3PO_4/Ag_2S/g-C_3N_4复合型光催化材料的活性与稳定性都得到明显提高,这主要归因于复合催化剂比表面积和孔结构的增加,载流子分离效率的提高。光催化机理研究表明,空穴(h~+)、超氧阴离子自由基(·O~(2-))和羟基自由基(·OH)都是光催化过程中的主要活性物种。三者作用大小依次为:h~+·O~(2-)·OH。     

Enantiodivergent synthesis of trans-3,4-disubstituted succinimides by SmI2-mediated Reformatsky-type reaction

An enantiodivergent strategy for the synthesis of trans-3,4-disubstituted succinimides is reported. The key step is a highly trans-stereoselective SmI₂-induced Reformatsky-type reaction of 4-substituted-O-benzoylated malimides with carbonyl compounds. Double chirality transmissions were performed with good to excellent diastereoselectivities.     

Efficient synthesis of indenes by FeCl3·6H2O-catalyzed intramolecular Friedel-Crafts reaction of aryl-substituted allylic alcohols

An efficient procedure for the synthesis of substituted indenes through the FeCl₃·6H₂O-catalyzed intramolecular Friedel-Crafts cyclization of aryl-substituted allylic alcohols has been developed. This method features the easily available starting materials, cheap catalyst, simple manipulation, and mild conditions.     

Synthesis of β-amino carbonyl compounds via a Zn(OTf)2-catalyzed cascade reaction of anilines with aromatic aldehydes and carbonyl compounds

A Zn(OTf)₂-catalyzed cascade reaction of anilines with aromatic aldehydes and carbonyl compounds was described. This one-pot three-component reaction afforded the corresponding β-amino carbonyl compounds, β-amino esters, and β-amino ketones in good to excellent yields. The reaction was also applied for the liquid-phase synthesis of β-amino carbonyl compound library using PEG as a support.     

Baylis-Hillman reaction promoted by a recyclable protic-ionic-liquid solvent-catalyst system: DABCO-AcOH-H2O

A recyclable protic-ionic-liquid solvent-catalyst system, DABCO-AcOH-H₂O, has been developed and used in the Baylis-Hillman reaction of aromatic aldehydes, aliphatic aldehydes, and cinnamaldehydes with acrylates and acrylonitrile, showing comparable performance to free DABCO in traditional solvents. The DABCO-AcOH-H₂O solvent-catalyst system could be reused for at least five times without significant loss of activity.     

Selective formation of 2-imidazolines and 2-substituted oxazoles by using a three-component reaction

Selective formation of 2H‐2‐imidazolines and 2‐substituted oxazoles by using a multicomponent reaction of amines, either aldehydes or ketones, and α‐acidic isocyano amides or esters is described. By selecting the appropriate solvent, Ag^I or Cu^I catalyst, or by employing a weak Brønsted acid, the product formation can be fully controlled and directed quantitatively to the desired heterocyclic scaffold. The described experimental procedures not only significantly increase the scope of compatible inputs for this complexity‐generating three‐component reaction, but also allow for considerable chemical diversity: At least four diversity points in two distinct scaffolds can be exploited in this way.     

Facile synthesis of 1,2,4-triazolines via PPh3-triggered reaction of azodicarboxylate with 2-azidoacrylates

A convenient method for the synthesis of 1,2,4-triazolines by triphenylphosphine-triggered reaction of dialkyl azodicarboxylate with 2-azidoacrylates is described. The cascade reaction procedure is general and efficient.     

Regioselective ring-opening of epoxides with amines using Zn(ClO4)2-Al2O3 as a heterogeneous and recyclable catalyst

A simple and efficient method has been developed for the synthesis of β-amino alcohols by regioselective ring-opening of epoxides with amines in the presence of zinc perchlorate-neutral alumina as a heterogeneous recyclable catalyst at room temperature in high yields.     

Aqueous C-S cross-coupling: synthesis of 2-iminobenzo-1,3-oxathioles via CuCl2·H2O-catalyzed tandem reaction of 2-iodophenols with isothiocyanates

A CuCl₂·H₂O-catalyzed tandem reaction of 2-iodophenol with isothiocyanate in water is described, which provides an environmentally benign, efficient, and practical route for the generation of 2-iminobenzo-1,3-oxathiole. It was noteworthy that most of the products were easily separated from the reaction system by simple filtration.     

Solubility of trans-Co2(CO)6 [3,5-bis(CF3)C6H3P(i-C3H7)2] in dense carbon dioxide

The title compound (1) was prepared by the reaction of 3,5-bis(CF₃)C₆H₃P(i-C₃H₇)₂ (L1) and Co₂(CO)₈. Its solubility in supercritical carbon dioxide was measured at varying temperatures and pressures using a modified analytical extraction device. Solubility data were determined in the temperature and pressure ranges between 40 and 70 °C and between 100 and 300 bar, respectively. The solubility of 1 is lower compared to (p-CF₃C₆H₄)₃P, but much higher than for transition metal complexes bearing phosphines without fluorinated substituents.     

Supramolecular helical architecture assembled by double-helical [Ag2L2] units

A series of new sterically hindered bridged ligand 4,4^′-methylene-N,N^′-bis(phenyl-2-pyridylmethylene)-bis(2,6-dialkylanil)s was efficiently synthesized by the condensation reaction of 4,4^′-methylene-bis(2,6-disubstituted aniline) and benzoyl pyridine. They easily coordinated with Ag(I) to form Ag(I) complexes. The structure of complex [Ag₂L⁴₂][ClO₄]₂ was determined by the single X-ray crystallographic analysis, and the double-helical asymmetric unit containing two [Ag₂L⁴₂] moieties was interconnected with the adjacent unit through hydrogen bonds to form a helical supramolecular architecture.     

One-pot three-component synthesis of α-amino nitriles catalyzed by nano powder TiO_2 P 25

A simple and efficient method has been developed for the synthesis ofα-amino nitriles from aldehydes,amines and trimethylsilyl cyanide（Me₃SiCN） in the presence of a catalytic amount of cyanuric acid at room temperature.     

表面覆盖SiO2用于提高Pt-Pd/CeO2-ZrO2-Al2O3商用柴油机氧化型催化剂的抗硫性

向Pt-Pd/CeO₂-ZrO₂-Al₂O₃ （Pt-Pd/CZA）商用柴油机氧化型催化剂（DOC）中加入多孔SiO₂以提高其抗硫性. 使用多层涂覆法在Pt-Pd/CZA 催化剂表面覆盖一层多孔SiO₂,从而制得SiO₂/Pt-Pd/CeO₂-ZrO₂-Al₂O₃（SiO₂/Pt-Pd/CZA）抗硫DOC. 并使用扫描电子显微镜（SEM）,H₂程序升温还原（H₂-TPR）,氮气吸脱附,X射线能谱（EDX）和热重分析（TGA）等对其进行表征. SEM结果显示,SiO₂层以多孔形式均匀覆盖在催化剂表面. 氮气吸脱附结果表明,所添加的SiO₂的织构性质与Pt-Pd/CZA 催化剂的织构性质相似,因而表面覆盖的SiO₂并未明显改变Pt-Pd/CZA催化剂的比表面积和孔结构. H₂-TPR结果证实表面覆盖的SiO₂不影响Pt-Pd/CZA催化剂的还原性能. EDX和TGA结果说明表面覆盖SiO₂可以抑制硫物种在催化剂表面的形成及累积. 最终,本文所制备的SiO₂/Pt-Pd/CZA催化剂在保持Pt-Pd/CZA商用DOC的高活性及耐久性的同时有效提高了其抗硫性.