二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.     

Sodium carbonate mediated regioselective synthesis of novel N-(hydroxyalkyl)cinnamamides

A synthetic protocol for the direct synthesis of N-(hydroxyalkyl)cinnamamides from cinnamates and aminoalcohols in the presence of sodium carbonate as the base is presented. A wide variety of N-(hydroxyalkyl)cinnamamides were isolated in up to 99% yields. The reaction is highly regioselective and yields only N-acylated products by 1,2-addition of aminoalcohols to cinnamates.     

NaNO2/I2 as an alternative reagent for the synthesis of 1,2,3-benzotriazin-4(3H)-ones from 2-aminobenzamides

An efficient transformation of 2-aminobenzamides to 1,2,3-benzotriazin-4(3H)-ones in the presence of sodium nitrite (NaNO₂) and Iodine (I₂) is described. The reaction is proposed to proceed via formation of nitrosyl halide that induces nitrosylation of the amino group of 2-aminobenzamide leading to diazotization followed by intramolecular cyclization.     

核壳结构CdS/ZnS纳米微粒的制备与光学特性

CdS and CdS/ZnS core-shell structure nano particles were synthesized in micro emulsion, and characterized by X-ray diffraction(XRD), transmission electron microscopy (TEM), UV absorption spectra and PL. The average diameter of CdS was about 3.3 nm, and CdS/ZnS core-shell structure was confirmed by XRD and UV. Considering the optical properties of CdS/ZnS core-shell structure nanoparticles which have different ZnS shell thickness, the UV absorption edge of CdS/ZnS becomes as lightred-shift with the thickness of ZnS layer increasing, and the absorption of shortwave band is strongly enhanced at the same time. The PL spectra indicate that ZnS shell layer can greatly eliminate surface defects of CdS nanoparticles and make its band-edge directed recombination increased, and the luminous efficiency of CdS is improved greatly when it has appropriate shell thickness.     

EFFECT OF SUBSTITUTION POSITION OF HYDROXY GROUP AT BENZOIC ACID ON THE LUMINESCENT AND DEGRADATION PROPERTIES OF POLY[DI（CARBOXYPHENYL） SUCCINATE-co-SEBACIC ANHYDRIDE]S

In this work, two new diacids, di（m-carboxyphenyl） succinate （m-dCPS） and di（o-carboxyphenyl） succinate （o- dCPS）, were synthesized by reaction of m-, o-hydroxy benzoic acid with succinic chloride, respectively. Their corresponding copolymers with sebacic acid （SA）, P（m-dCPS：SA） and P（o-dCPS：SA）, were prepared by melt copolycondensation and characterized by NMR, UV and DSC methods. Compared with inherently fluorescent poly[di（p-carboxyphenyl） succinate- co-sebacic anhydride] （P（p-dCPS：SA））, P（m-dCPS：SA） and P（o-dCPS：SA） displayed different luminescent properties. P（m- dCPS：SA） could emit fluorescence under the excitation of both visible and UV light, while P（o-dCPS：SA） could only emit fluorescence when excited with UV light. Degradation rate of the two new copolyanhydrides increased with the increase of SA fraction in the copolymers. In addition, P（o-dCPS：SA） degraded more rapidly than P（m-dCPS：SA） with the same composition. Typical surface-degradation characteristics of these copolyanhydrides were observed.     

Synthesis, Crystal Structure and Characterization of a New Mononuclear Zn(Ⅱ) Complex from Schiff-base Ligand

A new mononuclear [Zn(H-1L)2] (L = 1H-indole-3-ethylene-salicylaldimine) was synthesized through the reaction of Zn(Ac)2, salicylaldehyde and tryptamine in hot ethanol solution and characterized by X-ray crystal structure analysis. The crystal belongs to monoclinic, space group P21/n with a = 15.014(2), b = 10.857(1), c = 17.489(1) , β = 95.49(1)°, V = 2837.8(5) 3, Z = 4, Dc = 1.386 g/cm3, μ = 0.904 mm-1, F(000) = 1232, the final R = 0.0463 and wR = 0.0890 for 4990 independent reflections. In the complex, the Zn2+ ion presents a distorted N2O2 tetrahedral coordination involving two H-1L ligands.     

A new microwave-assisted,three-component reaction of 5-aminopyrazole-4-carboxylates: Selective synthesis of substituted 5-aza-9-deaza-adenines

A series of 5-aza-9-deaza- analogues of purine was effectively prepared using highly selective annulation of 1,3,5-triazine ring onto 5-aminopyrazole-4-carboxylates via a one-pot, multicomponent, microwave-assisted approach. The products were obtained in good yields and high purity. This catalyst-free method was demonstrated to be scalable and highly reproducible in different microwave reactors. Some structural features of the prepared compounds were studied in details using dynamic NMR spectroscopy and X-ray crystallography.     

Total synthesis of (−)-vindoline

In this full paper, a stereocontrolled strategy for the total synthesis of (?)-vindoline is described. This synthetic route features: 1) rapid construction of the stereochemical center at C19 through a highly diastereoselective vinylogous Mannich addition; 2) tandem Heathcock/aza-Prins cyclization to install rings C and E in vindoline; 3) oxidative transformation of β-ketoester to enone; 4) stereoselective inversion of C4 stereochemistry with triphenylphosphine and carbon tetrabromide followed by Brønsted acid.     

Convenient synthesis of 2-(het)arylpyrrolidines via stable 1-pyrrolinium salts

The efficient method for the synthesis of 2-(het)aryl-substituted pyrrolidines possessing exocyclic carbon-carbon double bond via the Mannich-type reaction of stable 3-arylidene-1-pyrrolinium salts with different heterocyclic C-nucleophiles is proposed.     

Exploration of polystyrene-supported 2-isobutoxy-1-isobutoxycarbonyl-1,2-dihydroquinoline (PS-IIDQ) as new coupling agent for the synthesis of 8-substituted xanthine derivatives

Polystyrene-supported 2-isobutoxy-1-isobutoxycarbonyl-1,2-dihydroquinoline (PS-IIDQ), a polymer supported covalent coupling reagent, was successfully employed for the first time in the synthesis of 8-substituted xanthine derivatives. PS-IIDQ was observed to be more efficient than IIDQ and polymer-supported carbodiimide (PS-EDC).     

Synthetic studies toward bicyclic endoperoxides presenting polar side chains

We developed a synthetic strategy for the preparation of tetrahydrofuro[2,3-c][1,2]dioxane and 2,3,8-trioxa[3,3,1]nonanes bearing polar functional groups at C3 and C4, respectively. The synthetic strategy has been applied to the synthesis of 2,3,8-trioxa[3,3,1]nonanes bearing various amides and amines at C3 useful for structure-activity relationships investigation as antiplasmodial compounds. The synthesis of 1 and the reaction conditions identified for its conversion to amides and amines could pose the basis for the use of this class of endoperoxides also in conjugation with other drugs for polypharmacology approaches.