Direct [3+2]-cycloaddition of electron-deficient alkynes with CF3CHN2: Regioselective one-pot synthesis of 3-trifluoromethylpyrazoles

A direct and facile cycloaddition reaction of electron-deficient terminal alkynes with 2,2,2-trifluorodiazoethane under mild conditions to afford a series of 5-substituted 3-trifluoromethylpyrazoles in high yields is described. The potential application of this cycloaddition reaction was demonstrated via the efficient synthesis of a key intermediate of the antiviral drug AS-136A and a fluorinated analog of Tebufenpyrad.     

TBAI-mediated regioselective sulfenylation of indoles with sulfonyl chlorides in one pot

A versatile method for the synthesis of 3-sulfenylated indoles via TBAI promoted sulfenylation of indoles with sulfonyl chlorides in one pot has been presented. This system features highly regioselective, metal-free, easy operation, and shows a broad functional group tolerance leading to excellent yields. And this reaction could be easily conducted in 10?mmol scale with high effectivity. A plausible mechanism is proposed.     

Direct construction of 3',4'-dihydrospiro[pyrrol-3,2'-oxindoles] through a cascade Michael/cyclization reaction of 3-aminoindolin-2-ones with enones/enals

A simple and efficient cascade Michael/cyclization reaction of 3-aminoindolin-2-ones with enones/enals was identified for the synthesis of potentially biologically active 3',4'-dihydrospiro[pyrrol-3,2'-oxindoles], using DBU as an efficient catalyst and ethylene glycol as an environmentally benign solvent. More diverse 3',4'-dihydrospiro[pyrrol-3,2'-oxindoles] analog libraries were prepared in good yields (up to 97%). The structure of 3',4'-dihydrospiro[pyrrol-3,2'-oxindoles] was confirmed by mass spectrometry analysis, NMR analysis and single crystal X-ray diffraction. The main advantages of this method include the availability of startingmaterials, simple experimental operation, short reaction time, as well as high yields observed.     

Selective Metallation of 3-Halothiophenes: Practical Methods for the Synthesis of 2-Bromo-3-formylthiophene

Selective lithiation of 3-bromothiophene was accomplished under controlled conditions without formation of undesired thienyllithium compounds. A thienyl Grignard reagent derived from 2-bromo-3-iodothiophene was transformed into 2-bromo-3-formylthiophene in high selectivity by formylation with dimethylformamide (DMF) at optimal reaction temperature.     

B(C6F5)3-Catalyzed Aza-Friedel–Crafts Reaction of Indolizines with 2-Aryl-3H-indol-3-ones

A Friedel–Crafts reaction of indolizines with 2-aryl-3H-indol-3-ones catalyzed by B(C₆F₅)₃ is described. This protocol gives access to indolizine derivatives that are valuable building blocks in synthetic and pharmaceutical chemistry. The reaction proceeds under mild conditions, affording various C2-quaternary indolin-3-ones based on indolizine with high yields and regioselectivities. Moreover, the synthetic transformations of the target products were realized by N-methylation and trifluoromethane sulfonation.     

A new diastereoselective multicomponent, one-pot strategy for the synthesis of 3-substituted isoindolinones via efficient C-C bond formation

A new three-component reaction among o-phthalaldehyde, N-alkyl/aryl substituted urea, and an aromatic aldehyde has been developed at ambient condition, and a class of isoindolinones with novel C-3 substitution were conveniently synthesized. The general diastereomeric excess as high as over 99% of the products indicated the excellent stereoselectivity posed in this multicomponent reaction.     

L-tert-Leucine derived urea-ammonium salts: Efficient bifunctional phase transfer catalysts for highly diastereo- and enantioselective aza-Henry reaction of isatin-derived N-Boc ketimines with α-aryl nitromethanes

An efficient way of aza-Henry reaction between isatin-derived N-Boc ketimines and α-aryl nitromethanes catalyzed by bifunctional phase transfer catalysts with a quaternary ammonium center derived from L-tert-Leucine has been developed. A series of 3-substituted 3-amino-oxindoles were constructed by this catalytic protocol in excellent yields (90–99%), with high enantioselectivities (83–95%) and diastereoselectivities (79:21–97:3). The asymmetric aza-Henry reaction of N-Boc amidosulfones and α-aryl nitromethanes were also investigated and gave the corresponding products in high to excellent yields (72–97%) with high enantioselectivities (up to 99%) and diastereoselectivities (up to >99:1).     

甲烷氧化偶联催化剂La2O3／SrCO3—BaCO3的催化活性与表征

在甲烷氧化偶联制Ｃ２烃的研究中，人们发现碱土金属与稀土金属组成的复合氧化物催化剂具有高的催化活性［１，２］．稀土化合物作为有希望的工业催化剂之一，已受到广泛的关注．一般认为，它们含有的氧空位对活化甲烷的有效氧物种有利．Ｄｅｂｅｙ等在１％Ｓｒ／Ｌａ２Ｏ...     

Multi‐Gram Scale Synthesis of Chiral 3‐Methyl‐2,5‐trans‐tetrahydrofurans

In this article, we report the rapid and facile synthesis of chiral 3‐methyl‐2,5‐trans‐tetrahydrofurans. This reaction utilizes cheap and easily available starting materials. A domino hydrolysis and intramolecular Michael‐type ring closure reaction was the key step. As a result, synthesis of the desired 3‐methyl‐2,5‐trans‐tetrahydrofurans could be achieved in gram‐scale over seven linear steps with high chemical yield and high diastereoselectivity.     

Benzylation of benzene and substituted benzenes by benzyl chloride over InCl3, GaCl3, FeCl3 and ZnCl2 supported on clays and Si-MCM-41

Liquid phase benzylation of benzene by benzyl chloride to diphenyl methane over InCl₃, GaCl₃, FeCl₃ and ZnCl₂ supported on commercial clays (viz. Montmorillonite-K10, Montmorillonite-KSF and Kaolin) or on high silica mesoporous MCM-41 (at 60, 70 and 80 °C) has been investigated. The supported InCl₃, GaCl₃ and FeCl₃ showed high activity for the benzylation of benzene. The redox function created due to the impregnation of the clays or Si-MCM-41 by InCl₃, GaCl₃, FeCl₃ or ZnCl₂ seems to play a very important role in the benzylation process. Among the catalysts, the InCl₃/Mont.-K10 showed both high activity and high selectivity for the benzylation. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene>toluene>mesitylene>anisole. The InCl₃ (or GaCl₃)/Mont.-K10 (or Si-MCM-41) catalyst showed high benzene benzylation activity even in the presence of moisture in the reaction mixture. The catalyst can also be reused in the benzylation for several times. Kinetics of the benzene benzylation (using excess of benzene) over the supported metal chloride catalysts have also been thoroughly investigated. A plausible reaction mechanism for the benzylation over the supported metal chloride catalysts is proposed.     

Reaction kinetics of glycidyl trimethyl ammonium chloride and chitosan in 1-allyl-3-methylimidazolium chloride

The modification of chitosan in ionic liquids through homogeneous reactions has advantages including shorter time and simple post-treatment and the generated chitosan derivatives have high degrees of subsititution and good reproducibility. In this paper, we studied the reaction kinetics of glycidyl trimethyl ammonium chloride and chitosan in 1-allyl-3-methylimidazolium chloride. Chitosan concentration, temperature, and reaction time were studied to determine their influence on reaction kinetics. The results indicated that reaction rate increased with increases of both chitosan concentration and temperature. A first-order kinetics equation was generated, where the relationship between reaction rate constant and temperature was determined.     

Selective N-Alkylation of 2-Amino-4H-chromene-3-carbonitrile Derivatives with Alcohols Catalyzed by AlCl3 Under the Assistance of CH3COOH

A highly efficient and selective N-alkylation reaction of 2-amino-4H-chromene-3-carbonitrile derivatives using various alcohols as alkylation agent were developed in the presence of AlCl₃ as a catalyst as well as CH₃COOH as an additive, in which the cyano group kept inert and the amino group was alkylated in high yields. All the target products were characterized and determined by infrared(IR), ¹H NMR, ¹³C NMR, and HRMS. And the X-ray structure of product 3ab was obtained. A bimolecular reaction mechanism catalyzed by AlCl₃ was proposed under the assistance of CH₃COOH.     

A green method for the synthesis of bis–indolylmethanes and 3, 3'-indolyloxindole derivatives using cellulose sulfuric acid under solvent-free conditions

<正>A highly efficient green protocol for the preparation of bis-indolylmethanes,bis-2-methylindolylmethanes,bis-1-methylindolylmethanes and 3,3'-diindolyloxindole derivatives from the reaction of indoles with various aldehydes and ketones in the presence of cellulose sulfuric acid under solvent-free conditions is reported.The significant features of this procedure are high yields of the products,mild reaction,solvent-free condition and non-toxicity of the catalyst.     

Highly Efficient InBr3 Catalyzed Michael Addition of Indoles to α, β-Unsaturated Esters

A highly efficient synthetic strategy toward Michael addition of indoles to α,β‐unsaturated esters has been developed using Lewis acid InBr₃ as catalyst. The reactions generated 3‐substituted indoles in high yields with excellent regio‐selectivity in the presence of catalytic amount of InBr₃ under mild reaction conditions. The method is simple, efficient and practical.     

Radical Cation Salt‐initiated Aerobic C−H Phosphorylation of N‐Benzylanilines: Synthesis of α‐Aminophosphonates

A radical cation salt‐initiated phosphorylation of N‐benzylanilines was realized through an aerobic oxidation of the sp³ C?H bond, providing a series of α‐aminophosphonates in high yields. An investigation of the reaction scope revealed that this mild catalyst system is superior in good functional group tolerance and high reaction efficiency. The mechanistic study implied that the cleavage of the sp³ C?H bond was involved in the rate‐determining step.     

Synthesis of a Polymer-bound Sensitizer and its Application in the Photoisomerization of trans-Vitamin D_3 to cis-Vitamin D_3

The photochemistry of the vitamin D family and their precursors has been the subject of extensive studies for many years1-4. Most of the studies focus on the photoisomer- ization of 7-dehydrocholesterol and that of tachysterol to previtamin D3, which is of commercial importance in the synthesis of vitamin D34, 5. Recently the cis/trans isomerization of vitamin D analogs (Scheme 1) draws attention because of its importance in the synthesis of hydroxylated vitamin D metabolites6. However, o…     

Caffeine gold complex supported on magnetic nanoparticles as a green and high turnover frequency catalyst for room temperature A3 coupling reaction in water

A new heterogeneous catalyst derived from gold (III) and supported on caffeine‐coated magnetic nanoparticles, Fe₃O₄@Caff‐Au, has been prepared and characterized using different techniques. This magnetic gold composite shows high catalytic activity in A³ coupling reactions of terminal alkynes, aldehydes and secondary amines. Using this green catalyst, propargylamines are obtained in high turnover frequency in short reaction times using water as solvent at room temperature. This stable and ready accessible catalyst can be easily recycled magnetically for at least nine consecutive runs without significant loss of activity and with slight aggregation of Au species.     

A novel Friedlander-type synthesis of 3-aryl quinolines from 3-oxo-2,3-diaryl-propionaldehydes

3-Aryl quinolines are readily synthesized by a novel Friedländer-type reaction with 3-oxo-2,3-diaryl-propionaldehydes and 2-amino arylaldehydes. A preliminary mechanism of this novel one pot, two-step synthesis has been explored with the proofs of isolation of the enaminone intermediate and the eliminated benzoic acid in this reaction.     

Carbon dioxide-mediated synthesis of 3(2H)-furanones from diyne alcohols

A novel type of carbon dioxide-mediated reaction of diyne alcohols without any metal catalysts was reported. Carbon dioxide held the key to the success of this reaction, in which 3(2H)-furanones were selectively obtained in moderate to high yields.     

三乙基铝-乙酰基丙酮金属配合物-水配合体系引发对二氧环己酮(PDO)开环聚合的研究

近年来,生物降解材料受到了越来越广泛的关注．聚对二氧环己酮(PPDO)具有优异的生物相容性、生物可吸收性、生物降解性和良好的柔韧性,目前已被成功地应用于医用材料领域．而在环境材料如薄膜、板材、发泡材料等领域也具有广泛的应用前景．PPDO作为一种新材料,虽然早在20世纪70年代就已经合成出来,