The effects of TiO_(2)crystal-plane-dependent Ir-TiO_(x)interactions on the selective hydrogenation of crotonaldehyde over Ir/TiO_(2)catalysts

Three supported Ir/TiO_(2)catalysts,containing anatase TiO_(2)nanocrystals with predominantly exposed{101},{100},and{001}planes,were subjected to various pre-treatments(H2 reduction at different temperatures and O_(2)re-oxidation)and then tested in the vapor phase selective hydrogenation of crotonaldehyde.The pre-treatments significantly altered the Ir-TiO_(x)interactions,including the morphologies and electronic properties of the Ir species and their surface acidity.These interactions were also closely related to the crystal planes of TiO_(2),which further supported the observed reaction behaviors of the various Ir/TiO_(2)catalysts.The best performance was obtained using the Ir/TiO_(2)-{101}catalyst pre-reduced at 300℃,owing to its higher Ir^(0)surface concentration and moderate surface acidity compared to the other catalysts.Moreover,these findings indicated the synergistic role of the Ir-TiO_(x)interface in the reaction,as the interfacial sites were responsible for the adsorption/activation of H_(2)and the C=O bond in the crotonaldehyde molecule.However,pre-reduction at 400℃resulted in partial encapsulation of the Ir particles by TiO_(x)via strong metal-support interactions,which is unfavorable for the catalytic reaction owing to the loss of Ir-TiO_(x)interfacial sites.

Stereoselective cycloaddition of N-acyliminium cations withα,β-unsaturated ketones and esters

The cycloaddition of N-acyliminium cations with some deactivated alkenes such as α,β-unsaturate ketones and esters has been investigated. In most cases, the N-acyliminium cations produced from 3-hydroxy-2-arylisoindol-1-ones in the presence of BFa.OEt2 could be reacted with α,β-unsaturated ketones and esters to afford stereoselectively the cycloaddition products 6-acylisoindolo[2,1- a]quinolin-11-ones in moderate to high yields. C 2009 Wei Zhang. Published by Elsevier B.V, on behalf of Chinese Chemical Society. All rights reserved.

Zero-oxidation state precursor assisted fabrication of highly dispersed and stable Pt catalyst for chemoselective hydrogenation ofα,β-unsaturated aldehydes

The chemoselective hydrogenation ofα,β-unsaturated aldehydes is a key strategy for the synthesis of fine chemicals.Herein,we developed an efficient method of depositing Pt particles on FeO_(x)/SBA-15.This strategy is dependent on using a platinumdivinyltetramethyldisiloxane complex(Pt^(0)-DVTMS)as the precursor,which we demonstrate can be removed through a H_(2)-treatment under mild conditions.This,in turn,allowed for the synthesis of catalysts with well dispersed Pt particles.The presence of FeO_(x) species also aided Pt dispersion;when coated onto SBA-15,FeO_(x) strongly interacted with dissociated Pt species,inhibiting both Pt aggregation and metal leaching.Using cinnamaldehyde as a modelα,β-unsaturated aldehyde,it was demonstrated that this catalyst was highly selective towards the unsaturated alcohol and no obvious loss in activity was observed over five recycles.This catalyst was determined to be significantly more effective than an analogous catalyst prepared using chloroplatinic acid as a precursor,evidencing the importance of using the Pt0-DVTMS precursor.We corroborate the excellent catalytic performance to highly dispersed Pt-species,whereby Pt0 and Pt^(2+) play a critical role in activating H_(2) and the C=O bond.This research demonstrates that the Pt precursor can have a significant impact on the physicochemical properties and thus,the performance of the final catalyst.It also evidences how metal support interactions can dramatically influence selectivity in such hydrogenation reactions.This novel catalyst preparation protocol,using a DVTMS ligand for Pt impregnation,offers a facile approach to the design of multi-component heterogeneous catalysts.

Organocatalytic enantioselective Michael addition reactions of fluoromalonates with α,β-unsaturated aldehydes

A new organocatalytic enantioselective Michael addition of α-fluoromalonate to enals has been developed.The process is efficiently catalyzed by readily available chiral diphenylpyrolinol TES ether under mild reaction conditions to afford versatile highly enantioenriched fluorinated aldehydes.

Enantioselective Organocatalytic Aza-Michael Additions of Phthalimide Derivatives to α,β-Unsaturated Aldehydes

Phthalimide derivatives as nitrogen nucleophiles with α,β-unsaturated aldehydes for asymmetric aza-Michael additions have been reported. The reactions proceed smoothly to afford corresponding Michael adducts in good yields （up to 98%） and enantioselectivities （up to 95% ee）.

Microwave promoted one-pot synthesis of 3-(2′-amino-3′-cyano-4′-arylpyrid-6′-yl)coumarins

A facile procedure for the synthesis of 3-（2′-amino-3′-cyano-4′-arylpyrid-6′-yl） coumarins are being reported starting from 3- acetylcoumarin, aromatic aldehydes and malononitrile. The reactions were carried out on microwave irradiation in good yield with short time and easy work-up. The structures of all the compounds have been confirmed on the basis of their analytical, IR, ^1H NMR, and mass spectral data.

An Abnormal Reaction of N- (2,4-dinitrophenyl)-L-proline with Thionyl Chloride

N- (2,4-Dinitrophenyl)-4-amino-n-butyl aldehyde 3 was obtained with high yield of 80% when N- (2,4-dinitrophenyl)-L-proline 1 reacted with SOCl2 at room temperature. However, the anticipated product N- (2,4-dinitrophenyl)-tetrahydropyrrolyl-2- (4-methylthiophenyl) ketone 2 did not be produced. The mechanism was discussed in this article.

((3-(3-硅胶丙基)硫基)丙基)硫酸酯作为可回收催化剂用于合成4,4'-芳亚甲基-双(1H-吡唑-5-醇)(英文)

Sulfuric acid ([3-(3-silicapropyl)sulfanyl]propyl)ester is employed as a recyclable catalyst for the condensation reaction between aromatic aldehydes and 3-methyl-l-phenyl-5-pyrazolone. This condensation reaction was performed in ethanol under refluxing conditions giving 4,4'-alkylmethylene-bis(3-methyl-5-pyrazolones) in 74-90% yields. The heterogeneous catalyst was recycled and used in eleven runs for the reaction between benzaldehyde and 3-methyl-l-phenyl-5-pyrazolone without losing catalytic activity.

Sulfamic acid:An efficient,cost-effective and green catalyst for crossed-aldol condensation of ketones with aromatic aldehydes under solvent-free

Aromatic aldehydes undergo crossed-aldol condensation with ketones in the presence of catalytic amount of sulfamic acid （SA） to afford the corresponding α,β-unsaturated aldol products under solvent-free conditions in good to high yields at 45-80 ℃.

Regioselective synthesis of α-bromo-α,β-unsaturated carbonyl compounds via photocatalytic α-bromination reactions

A visible light-mediated approach for the preparation of α-bromo-α,β-unsaturated ketones and aldehydes was developed. In comparison to traditional methods that generally take two steps to afford the above compounds, this protocol was highlighted by its operational simplicity, avoiding using hazardous bromine and mild reaction conditions.

Studies on the synthesis of amino acids XII.Solid-liquid phase transfer catalytic dicondensation of 1,4-diacety1-2,5-piperazinedione with aldehydes

3,6-Diarylidene-2,5-piperazinediones(2)and 3-alkylidene-6-arylidene-2,5-piperazfnediones (6)were synthesized from diacetyl-2,5-piperazinedione(1)under solid-liquid phase transfer catalytic conditions.2 could be easily convered to a-amino acid by reducing with zinc powder and hydrolyzing with concentrated hydrochloric acid.The effect of different phase transfer catalysts and reaction con- ditions were studied.

Relationship between oil fume mutagens in ambient air and the deterioration of heated edible oils

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(4S,4'S)-2,2'-(4,6-Dibenzofurandiyl)bis[4,5-dihydro-4-phenyloxazole]-Ni(Ⅱ)Complexes Catalyzed Highly Enantioselective Nitrile Imine Cycloaddition Reactions

The Ni(Ⅱ)-chiral(4S,4'S)-2,2'-(4,6-dibenzofurandiyl)bis[4,5-dihydro-4-phenyloxazole](DBFOX/Ph)-catalyzed asymmetric 1,3-dipolar cycloadditions of nitrile imines to N-α,β-unsaturated acylpyrazoles was presented.This tactic rendered a facile and feasible route to prepare the optically active tetrasubstituted 5-3,5-dimethylpyrazole acyl dihydropyrazole cy-cloadducts bearing one or two contiguous stereocenters in good yields(up to 97%yield)with high regioselectivities(100%)and enantioselectivities(up to 97.5%ee).Following that,chiral cycloadducts could be obtained consistently in good chemical yields with excellent enantioselectivities within the gram scale process,additionally,toward five kinds of derivatization reac-tions like nucleophilic and reduction for further conversion of chiral cycloadducts to related chiral dihydropyrazole derivatives encompassing different substituents.

乳腺浸润微乳头状癌中乙醛脱氢酶-1表型细胞的研究

目的：探讨肿瘤干细胞标志物乙醛脱氢酶-1（aldehyde dehydrogenase-1，ALDH-1）在乳腺浸润性微乳头状癌（ invasive micropapillary carcinoma ，IMPC）原发灶及淋巴结转移灶中的表达及临床意义。方法选取乳腺IMPC伴淋巴结转移103例和非特殊型浸润性导管癌伴淋巴结转移（ invasive ductal carci-noma not otherwise specified ，IDC-NOS）110例的石蜡包埋组织标本，所有入选病例术前均未经放、化疗治疗。免疫组织化学染色技术检测2组肿瘤原发灶和相应的淋巴结转移灶癌组织中ALDH-1的表达、定位和分布情况，并分析其与乳腺癌各临床病理学特征之间的关系及预后意义。结果①IMPC组原发灶及淋巴结转移灶中肿瘤细胞 ALDH-1阳性表达率[原发灶37.9％（39/103）；淋巴结转移灶47.6％（49/103）]，明显高于IDC-NOS组[原发灶21.8％（24/110）；淋巴结转移灶23.6％（26/110）]，差异有统计学意义（P＜0.05）。②IMPC原发灶及淋巴结转移灶中肿瘤细胞ALDH-1阳性表达与患者的肿瘤大小、组织学分级、淋巴结转移、ER阴性状态、PR阴性状态、HER2过表达呈明显正相关（P＜0.05）。③与IDC-NOS组相比，IMPC组患者的无病生存期明显缩短，差异具有统计学意义（ P＝0.003）。淋巴结阳性乳腺IMPC原发灶及淋巴结转移灶肿瘤细胞中 ALDH-1蛋白阳性表达患者的无病生存期明显低于其阴性表达患者，差异有统计学意义（ P＜0.05）。多因素分析乳腺IMPC转移淋巴结中ALDH-1蛋白阳性表达与患者的预后差有关（P＝0.005）。结论 ALDH-1可作为淋巴结阳性乳腺IMPC患者预后不良的指标，且IMPC肿瘤细胞中干细胞的存在可能是导致IMPC高淋巴管侵袭、高淋巴结转移及耐药等恶性生物学行为的重要原因。

Gram-scale preparation of dialkylideneacetones through Ca(OH)_2-catalyzed Claisen-Schmidt condensation in dilute aqueous EtOH

A synthetic method of dialkylideneacetones has been developed. Compared with known protocols, the method employed catalytic Ca(OH)_2 as the cheap, mild base catalyst and dilute aqueous EtOH(20%, v/v)as the green and safe solvent. The procedure was easily operated: In most cases, the product could be isolated by a simple filtration, and purified by washing with water. This paper provided experimental details of the reactions, which could be applied in gram-scale synthesis and should be a very reliable and practical protocol to prepare these useful compounds in laboratory and at the industrial level.

Sulfuric acid {[3-(3-silicapropyl)sulfanyl]propyl}ester a recyclable catalyst for the synthesis of 2-aryl- 1-arylmethyl- 1H- 1,3-benzimidazole derivatives

A highly selective synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzimidazoles from the reaction of o-phenylenediamine and aromatic aldehydes in the presence of sulfuric acid{[3-(3-silicapropyl)sulfanyl]propyl}ester(SASPSPE)in water and at 80℃in good to excellent yields.

Self-Assembly Ultrathin Fe-Terephthalic Acid as Synergistic Catalytic Platforms for Selective Hydrogenation

Alloy nanoparticles(NPs)with numerous exposed catalytic active sites have been extensively studied as efficient heterogeneous catalysts.However,it is challenging to synthesize alloy NP catalysts with high activity while avoiding aggregation.Herein,we report a facile method to encapsulate alloy NPs loaded metal–organic framework(MOF)catalysts(alloy NPs/MOFs)within an ultrathin metal–organic layer using a terephthalic acid(BDC)assisted method.A series of metal-BDC encapsulated PtM/MOFs(M=Fe,Co,and Ni)catalysts were synthesized successfully and showed significantly enhanced catalytic performance toward selective hydrogenation reaction.