Yb(OTf)3-catalyzed synthesis of pyrroles under solvent-tree conditions

Ayb(Otf)3-catalyzed approach for the synthesis of pyrroles under solvent-free conditions was achieved,which could afford the desired products with yields ranged from moderate to excellent.     

Gallium trichloride-catalyzed conjugate addition of indole and pyrrole to α,β-unsaturated ketones in aqueous media

Michael addition of indole and pyrrole to a variety ofα,β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl_3 in aqueous media to afford the corresponding products in good to excellent yields.     

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

The cycloaddition of N-acyliminium cations with some deactivated alkenes such asα,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 BF_3·OEt_2 could be reacted withα,β-unsaturated ketones and esters to afford stereoselectively the cycloaddition products 6-acylisoindolo[2,1-a] quinolin-11-ones in moderate to high yields.     

Doebner condensation in ionic liquids [Bmim]BF_4 and [Bpy]BF_4 to synthesize α,β-unsaturated carboxylic acid

Ionic liquids[Bmim]BF_4 and[Bpy]BF_4 were employed as environmentally benign media in Doebner condensation to synthesizeαβ-unsaturated carboxylic acid.The good results showed that[Bmim]BF_4 and[Bpy]BF_4 were efficient media for Doebner condensation,which could be recycled easily.The highest yields could reach 93%and 90%in[Bmim]BF_4 and[Bpy]BF_4,respectively.     

Facile Aldol Reaction Between Unmodified Aldehydes and Ketones in Bronsted Acid Ionic Liquids

A series of condensation reactions of unmodified ketones and aromatic aldehydes to prepare α,β-unsaturated carbonyl compounds by means of Aldol reactions in Bronsted acid ionic liquids(BAILs)was explored.1-Butyl-3-methylimidazolium hydrogen sulphate(BMImHSO4)acting as an effective media and catalyst in aldol reactions was compared with other BAILs,with the advantages of high conversion and selectivity.The product was easily isolated and the left ionic liquid can be readily recovered and reused at least 3 times with almost the same efficiency.The scope and limitation of the present method were explored and the possible catalytic mechanism was speculated.     

Chemoselective Catalytic Hydrogenation of α,β-Unsaturated Ketones and α,β-Unsaturated Carboxylic Esters

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Catalytic conjugate addition of indole toα,β-unsaturated ketones by Co（ClO4）-2·6H2O/bis-Schiff base complexes

Co（ClO₄）)₂·6H₂O/bis-Schiff base complexes promoted the conjugate addition of indole toα,β-unsaturated ketones under mild conditions,giving the corresponding addition products with high yields.And the complex has been characterized with XRD and IR.     

Cu(OTf)_2-catalyzed ring-opening of epoxides with anilines:A convenient synthesis of β-amino alcohols

The regioselective ring-opening of epoxides with aniline and p-chlorop niline catalyzed by copper(Ⅱ) triflate provides the corresponding β-amino alcohols in excellent yields.     

One-step synthesis ofα,β-unsaturated arylsulfones by a novel multicomponent reaction of aromatic aldehydes,chloroacetonitrile, benzenesulfinic acid sodium salt

A new and green method for the synthesis of α,β-unsaturated arylsulfones had been achieved through the condensation of aromatic aldehydes,chloroacetonitrile,benzenesulfinic acid sodium salt in the presence of l-butyl-3-methyl imidazolium hydroxide([bmim]OH) in EtOH under reflux.The ionic liquid was recovered and recycled for subsequent reactions.The advantages of this protocol were non-toxic,easy work-up and good yields.     

A facile synthesis of 2,3-dihydro-2-aryl-4（1H）-quinazolinones catalyzed by scandium（Ⅲ） triflate

2,3-Dihydro-2-aryl-4(1H)-quinazolinones were prepared in good yields via condensation of o-aminobenzamide with aldehydes promoted by a catalytic amount of Sc(OTf)_3 under mild conditions.     

α,α-二乙酰基二硫缩烯酮与α,β-不饱和酮的加成反应研究

α,α-diacetyl ketene thioacetals had been investigated as odorless thiol equivalents in thia-Michael addition reaction.Under solvent-free conditions,a series of reactions between α,α-diacetyl ketene thioacetals and α,β-unsaturated ketones were carried out promoting by concentrated hydrochloric acid.The corresponding thia-Michael adducts in high yields were obtained.Furthermore,a mechanism for this thia-Michael addition reaction was proposed preliminary.     

Chemoselective hydrogenation of α,β-unsaturated aldehydes with modified Pd/C catalyst

Selective hydrogenation of α, β-unsaturated aldehydes with modified Pd/C catalyst was developed.The reduction of C=O bond could be efficiently inhibited by the addition of carbonates,and high selectivity to the corresponding saturated aldehydes was achieved under mild conditions.This protocol provides an alternative for efficient preparation of saturated aldehydes.     

Microwave-assisted synthesis of α-hydroxy aromatic ketones from α-bromo aromatic ketones in water

A reaction ofα-bromo aromatic ketones in water with microwave irradiation gave the correspondingα-hydroxy aromatic ketones in good yields.The use of microwaves was found to significantly improve yields and shorten the reaction time.This reaction afforded a very clean,convenient method for the synthesis ofα-hydroxy aromatic ketones.     

Polyethylene glycol radical-initiated aerobic propargylic oxidation in dense carbon dioxide

The selective aerobic oxidation of alkynes to correspondingα,β-acetylenic ketones was achieved in polyethylene glycol/dense CO₂/O₂ biphasic system without any catalyst or additive.The effects of reaction parameters,e.g.temperature,CO₂ pressure,PEG molecular weight and loading on the reaction were carefully examined.Moreover,various substrates worked well in the presence of PEG 1000 under 5 MPa of CO₂ and 2 MPa of O₂ at 100℃for 12 to 24 h and acceptable yield and selectivity could be obtained in most cases.Preliminary mechanistic investigations were also discussed.     

A Novel Green Preparation of α,α'-Bis (substituted benzylidene)-cycloalkanones Promoted by FeCl3·6H2O in Ionic Liquid

α, α'-Bis(substituted benzylidene)cycloalkanones were efficiently prepared fromcycloalkanones and benzaldehydes in [bmim][BF4] by using iron(Ⅲ) chloride hexahydrate as acatalyst. It is shown that [bmim][BF4] and iron(Ⅲ) chloride hexahydrate can be quantitativelyrecovered and be reused effectively for many times. Compared with the known methods, thisnovel process has the advantage of being an environmentally benign process together with goodyields and mild reaction conditions.     

Two new α,β-unsaturated butyrolactone derivatives from Pleione bulbocodioides

Two newα,β-unsaturated butyrolactone derivatives,4-(4″-hydroxybenzyl)-3-(3′-hydroxy-phenethyl)furan-2(5H)-one(1)and 3-(3′-hydroxyphenethyl)furan-2(5H)-one(2),together with one known phenolic compound(3),were isolated from the tubers of Pleione bulbocodioides(Franch.)Rolfe.Their structures were elucidated by analysis of spectroscopic data.     

Two new guaianolide-type sesquiterpenoids from Kadsura interior

Two new guaianolide-type sesquiterpenoids,4β,9β-dihydroxy-1α,5α-H-guaia-6,10(14)-dien(1) and 4β,9β,10α-trihydroxy-1α,5α-H-guaia-6-en(2),along with four known sesquiterpenoids(3a,3b,4 and 5),were isolated from Kadsura interior.Their structures and configurations were elucidated by spectroscopic methods including 2D-NMR and HR-MS techniques.Compounds 3a and 3b were obtained as a pair of enantiomers,and their structure and absolute configuration were established from their extensive NMR spectra and by single-crystal X-ray analysis.     

Keggin类杂多化合物催化α,β-不饱和羰基化合物环氧化

在乙睛溶剂中考察了一系列杂多化合物和过氧化氢水溶液催化的各种缺电子的α,β-不饱和羰基化合物的环氧化反应.在所研究的杂多化合物中,二缺位的[γ-SiW10(H2O)2O34](Bu4N)4显示出了最高的活性.