Sodium Hydrogen Sulfate as Effective and Reusable Heterogeneous Catalyst for the One-pot Preparation of 14H-[(Un)substituted phenyl]-dibenzo[a,j]xanthene Leuco-dye Derivatives

NaHSO₄•H₂O has been used as an efficient catalyst for the one-pot preparation of 14H-[(un)substituted phenyl]-dibenzo[a,j]xanthene leuco-dye derivatives by condensation of β-naphthol with substituted benzaldehydes under microwave and thermal conditions. This method has the advantages of high yields, a green reaction, an efficient and cost-effective method, simple procedures, short reaction time, and easy workup.     

An Efficient Synthesis of 2-Oxazolidinones by Palladium-catalyzed Oxidative Carbonylation of β-Aminoalcohols and 2-Aminophenol under Mild Conditions

Oxidative carbonylation of β-aminoalcohols and 2-aminophenol in Pd(OAc)2/I2 catalytic system to produce the corresponding 2-oxazolidinones was conducted with high yields and selectivities in short reaction time. Mild reaction conditions, high catalytic turnover frequency value, improved yields and selectivities are the remarkable features exhibited by this process.     

Iodine-catalyzed Efficient Synthesis of β-Keto Esters from Aldehydes and Ethyl Diazoacetate Under Solvent-free Conditions

An efficient procedure for the synthesis of β-keto esters from the reaction of aldehydes and ethyl diazoa-cetate catalyzed by iodine at room temperature under solvent-free conditions has been described. The catalytic procedure has the advantages of easily available catalyst,mild reaction conditions,high yields,and easy work-up.     

A mild,simple and efficient method for selectiveα-monobromination of 1,3-diketones and β-ketoesters using pyridinium bromochromate

Pyridinium bromochromate has been found to be a highly efficient and selective reagent for theα-monobromination of 1,3-diketones andβ-keto-esters in the absence of base,Lewis acid,or other catalyst.The products were formed in high to excellent yields under mild reaction conditions and in short reaction times.     

P-Dodecylbenzenesulfonic acid(DBSA),a Brфnsted acid-surfactant catalyst for Biginelli reaction in water and under solvent free conditions

We report herein the use of p-dodecylbenzenesulfonic acid(DBSA) as a catalyst for a one-pot Biginelli reaction to afford 3,4- dihydropyrimidinone derivatives in good to excellent yields.This reaction proceeds efficiently in water and under solvent free conditions.Comparisons of results indicate that although the yields are high and comparable for both methods,the reaction times are considerably shorter under solvent free conditions.     

Liquid-Phase Synthesis of Methyl (2Z)-2-Arylsulfonylmethyl-2- alkenoates from PEG-Supported α-Phenylselenopropionate

Treatment of lithio derivative of novel PEG-supported a-phenylselenopropionate with aldehydes, followed by oxidation-elimination with 30% hydrogen peroxide, formed Baylis-Hillman products, which were then reacted with sodium arylsulfinate. The resulting sulfonylated products were cleaved from the PEG efficiently affording methyl (2Z)-2-arylsulfonylmethyl-2-alkenoates in good yields and high purities.     

Solvent-free synthesis of substituted fve membered heterocycles: One-pot reaction of primary amine and alkyl propiolate or isothiocyanate in the presence of oxalyl chloride简

A novel, convenient and efficient approach to the synthesis of pyrrole and imidazole derivatives via the reaction between primary amines, alkyl propiolates or isothiocyanate and oxalyl chloride is described. The method offers several advantages including high yields of products and performing reaction under solvent-free conditions.     

高效和可重复使用的Zr-MCM-41催化剂催化Strecker反应合成氨基腈类化合物(英文)

The synthesis and characterization of Zr-MCM-41 nanoreactors and their catalytic activity in the synthesis of new amino nitrile derivatives by the Strecker reaction in high yields and in short reaction times is reported.     

Synthesis of the 1,3-oxathiolanes using asymmetrically oxiranes

An efficient synthesis of 1,3-oxathiolane-2-imin derivatives is described via one-pot reaction between arylisothiocyanats, asymmetrically substituted oxiranes and catalytic amount of methanol.The mild reaction conditions and high yields of the products exhibit the good synthetic advantage of this method.     

A simple and effcient approach to one-pot synthesis of mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates catalyzed by InCl3简

An efficient and straightforward procedure has been developed for the synthesis of highly substituted mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates via a one-pot, four-component domino reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in the presence of InCl3 （20 mol%） in MeOH at ambient temperature. The salient advantages of this method are mild reaction conditions, environmentally benign, high to excellent yields, shorter reaction times, easy operation and no column chromatographic separation.     

KF-蒙脱土催化下丙二腈与α,β-不饱和酮的迈克尔加成反应

本论文研究了KF-蒙脱土催化下丙二腈与α,β-不饱和酮的迈克尔加成反应,研究发现在不同的反应温度下可以得到加成和环化两种不同的产物。该方法和现有的方法相比具有产率高、反应条件温和、操作简单、试剂易得等优点。     

Microwave‐induced Stereoselectivity in Synthesis of trans‐4‐Aryl‐3‐methyl‐6‐oxo‐4,5,6,7‐tetrahydro‐2H‐pyrazolo[3,4‐b]pyridine‐5‐carbonitriles

A facile synthesis of trans isomers of 4‐aryl‐3‐methyl‐6‐oxo‐4,5,6,7‐tetrahydro ‐ 2H ‐ pyrazolo[3,4‐b]pyridine‐5‐carbonitriles via three‐component condensation reaction of an aldehyde, 3‐amino‐5‐methylpyrazole and ethyl cyanoacetate in acetonitrile has been developed under microwave irradiation. This one‐pot reaction proceeds without any catalyst in short times and gives the product in high selectivities and high yields.     

Brominated poly(isobutylene‐co‐para‐methylstyrene) (BIMS)‐clay nanocomposites: Synthesis and characterization

In this work, preparation and properties of different nanoclays modified by organic amines (octadecyl amine, a primary amine, and hexadecyltrimethylammonium bromide, a tertiary amine) and brominated polyisobutylene‐co‐paramethylstyrene (BIMS)‐clay nanocomposites are reported. The clays and the rubber nanocomposites have been characterized with the help of Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X‐ray diffraction (XRD). The X‐ray diffraction peaks observed in the range of 3 °–10 ° for the modified clays disappear in the rubber nanocomposites. TEM photographs show predominantly exfoliation of the clays in the range of 12 ± 4 nm in the BIMS. In the FTIR spectra of the nanocomposites, there are common peaks of virgin rubber as well as those of the clays. Excellent improvement in mechanical properties like tensile strength, elongation at break, and modulus is observed on incorporation of the nanoclays in the BIMS. Structure‐property correlation in the above nanocomposites is attempted. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4489–4502, 2004     

An Efficient Synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one Derivatives via Multi‐Component Approach

An easy, highly efficient and a new convenient one‐pot, two‐step approach to the synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one is described. These compounds were synthesized from 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐4‐hydroxy‐6‐methyl‐3,4‐dihydro‐2H‐pyran‐2‐one and α‐bromoketones in good yields. The compounds 4 were synthesized by a multi‐component reaction between 1 , 2 , and 3 and the prominent features of this protocol are mild reaction conditions, operation simplicity, and good to high yields of products.     

Selective Synthesis of 1,2‐Diarylpyrrolo[3,4‐b]pyridine‐5,7‐diones via Cyclization Reaction of β‐Enamino Imides with Cinnamaldehydes

The novel 1,2‐diaryl substituted pyrrolo[3,4‐b]pyridine‐5,7‐diones were selectively synthesized in high yields by the base catalyzed cyclization reaction of 3‐arylamino‐1‐methyl‐1H‐pyrrole‐2,5‐diones with cinnamaldehyde and its derivatives in acetonitrile at room temperature. However, when piperidinium trifluoroacetate was employed as catalyst, the reaction afforded a mixture of 1,2‐diaryl and 1,4‐diaryl substituted pyrrolo[3,4‐b]pyridine‐5,7‐diones in comparable yields.     

Efficient Synthesis of α‐Benzylidene‐γ‐methyl‐γ‐butyrolactones

A concise synthesis of α‐benzylidene‐γ‐methyl‐γ‐butyrolactones 5a – g from substituted benzaldehydes is described. Compounds 1a – g on reaction with phosphorane 2 , provide the pentenoates 3a – g , which can be hydrolyzed to the acids 4a – g . The latter are cyclized to the corresponding butyrolactones 5a – g in excellent yields. The pentenoates 3a – g , on acid catalyzed cyclization, also provide 5a – g in very high yields.     

Facile Access to cis‐2,6‐Disubstituted Tetrahydropyrans by Palladium‐Catalyzed Decarboxylative Allylation: Total Syntheses of (±)‐Centrolobine and (+)‐Decytospolides A and B

cis‐2,6‐Tetrahydropyran is an important structural skeleton of bioactive natural products. A facile synthesis of cis‐2,6‐disubstituted‐3,6‐dihydropyrans as cis‐2,6‐tetrahydropyran precursors has been achieved in high regio‐ and stereoselectivity with high yields. This reaction involves a palladium‐catalyzed decarboxylative allylation of various 3,4‐dihydro‐2H‐pyran substrates. Extending this reaction to 1,2‐unsaturated carbohydrates allowed the achievement of challenging β‐C‐glycosylation. Based on this methodology, the total syntheses of (±)‐centrolobine and (+)‐decytospolides A and B were achieved in concise steps and overall high yields.     

A One‐Pot Biginelli Synthesis of 6‐Unsubstituted 5‐Aroylpyrimidin‐2(1H)‐ones and 6‐Acetyl‐1,2,4‐triazin‐3(2H)‐ones

The three‐component Biginelli‐like cyclocondensation reaction of enamines 1 , urea, and aldehydes in dioxane/acetic acid efficiently afforded the corresponding 6‐unsubstituted 3,4‐dihydropyrimidin‐2(1H)‐ones 2 in good yields (Scheme 1, Table). The corresponding reaction of azaenamine (=hydrazone) 7 with benzaldehyde and urea afforded 6‐acetyl‐1,2,4‐triazin‐3(2H)‐ones in good yields (Scheme 3).     

立体选择性合成2-(a-噻吩甲酰基)-3-取代苯基-4-乙氧羰基-5-甲基-反式-2,3-二氢呋喃

溴化(a-噻吩甲酰基)甲基三苯鉮1与3-取代苯甲叉基-2,4-戊二酮 2以碳酸钾为碱,在苯中55℃条件下反应,可以较好的收率、高立体选择性地生成反-2-(a-噻吩甲酰基)-3-取代苯基-4-乙氧羰基-5-甲基-2,3-二氢呋喃3。产物结构均经波谱予以确定。本文还提出了生成产物的可能机理。     

Novel synthesis of 3‐phenylazo‐1,5‐benzothiazepines, ‐1,5‐benzoxazepines and ‐1,5‐benzodiazepines via a one‐pot reaction

Novel polysubstituted ‐1,5‐benzothiazepine, ‐1,5‐benzoxazepine, and ‐1,5‐benzodiazepine were prepared in good yields by the reaction of hydrazono derivatives with o‐thioaminophenol, o‐aminophenol and o‐phenylenediamine via a one‐pot reaction.