Synthesis of 4‐((2‐hydroxynaphthalen‐1‐yl)(aryl)methyl)‐5‐methyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐ones using nano‐Zn‐[2‐boromophenyl‐salicylaldimine‐methylpyranopyrazole]Cl2 nanoparticles

Nano‐Zn‐[2‐boromophenyl‐salicylaldimine‐methylpyranopyrazole]Cl₂ (nano‐[Zn‐2BSMP]Cl₂) as a nanoparticle Schiff base complex and a catalyst was introduced for the solvent‐free synthesis of 4‐((2‐hydroxynaphthalen‐1‐yl)(aryl)methyl)‐5‐methyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐ones by the multicomponent condensation reaction of various aromatic aldehydes, β‐naphthol, ethyl acetoacetate, and phenyl hydrazine at room temperature.     

TiO2‐Nanoparticles Catalyzed Synthesis of New Trifluoromethyl‐4,5‐dihydro‐1,2,4‐oxadiazoles and Trifluoromethyl‐1,2,4‐oxadiazoles

Synthesis of a new series of trifluoromethyl‐4,5‐dihydro‐1,2,4‐oxadiazoles and trifluoromethyl‐1,2,4‐oxadiazoles have been described by utilizing the reactions between amidoximes and trifluoroacetimidoyl chlorides. Trifluoromethyl‐4,5‐dihydro‐1,2,4‐oxadiazoles have been synthesized under mild conditions such as Na₂CO₃, THF‐H₂O, and titanium dioxide nanoparticles as catalyst in good to excellent yields. Also, trifluoromethyl‐1,2,4‐oxadiazoles have been synthesized directly from reaction of amidoximes and trifluoroacetimidoyl chlorides in a one‐pot manner in present of NaH, THF, and titanium dioxide nanoparticle as catalyst.     

Vapor‐Phase Aldolization of n‐Butyraldehyde to 2‐Ethyl‐2‐Hexenal over Solid‐Base Catalysts

Vapor‐phase aldol condensation of n‐butyraldehyde to 2‐ethyl‐2‐hexenal was studied at 1 atm and 150～ 300°C in a fixed‐bed, integral‐flow reactor by using NaX, KX, γ‐Al₂O₃ and Na/NaOH/γ‐Al₂CO₃ catalysts. Ion exchange of NaX zeolite with potassium acetate solution results in a decrease of crystallinity and apparent lowering of surface area, whereas the basic strength is enhanced. Treatment of γ‐Al₂O₃ with NaOH and Na causes a large decrease of the surface area but strong enhancement of the catalyst basicity. The catalytic activity on the basis of unit surface area is in the order Na/NaOH/γ‐Al₂O₃ < KXU < KXW < NaX >γ‐Al₂O₃, in accordance with the relative catalyst basic strength. The molar ratio of trimeric to dimeric products increases with increasing the reaction temperature and the catalyst basic strength except for Na/NaOH/γ‐Al₂O₃. Very high selectivity of 2‐ethyl‐2‐hexenal (>98.5%) was observed for reactions over NaX zeolite at 150°C. Based on the FT‐IR and the catalytic results, the reaction paths are proposed as follows: self‐aldol condensation of n‐butyraldehyde, followed by dehydration produces 2‐ethyl‐2‐hexenal, which then reacts with n‐butyraldehyde and successively dehydrates to 2,4‐diethyl‐2,4‐octadienal and 1,3,5‐triethylbenzene. For the reaction over NaX, the calculated Arrhenius frequency factor and activation energy are 314 mol/g·h and 32.6 kJ/mol, respectively.     

A Magnetically Separable Catalyst for Synthesis of 1‐Phenoxy‐2‐propanol Via Atom‐economic Reaction

A magnetically separable catalyst Al₂O₃‐MgO/Fe₃O₄ was prepared by Al₂O₃‐MgO supported on magnetic oxide Fe₃O₄ and charactered by FT‐IR, XRD and SEM. The mixed oxides afforded high catalytic activity and selectivity for synthesis of 1‐phenoxy‐2‐propanol from phenol and propylene oxide with 80.3% conversion and 88.1% selectivity to 1‐phenoxy‐2‐propanol. Especially, facile separation of the catalyst by a magnet was obtained and the catalytic performance of the recovered catalyst was unaffected even at the forth run.     

Palladium‐Catalyzed Annulation of 1,2‐Diborylalkenes and ‐Arenes with 1‐Bromo‐2‐[(Z)‐2‐bromoethenyl]arenes: A Modular Approach to Multisubstituted Naphthalenes and Fused Phenanthrenes

(Z)‐1,2‐Diaryl‐1,2‐bis(pinacolatoboryl)ethenes underwent double‐cross‐coupling reactions with 1‐bromo‐2‐[(Z)‐2‐bromoethenyl]arenes in the presence of [Pd(PPh₃)₄] as a catalyst and 3 M aqueous Cs₂CO₃ as a base in THF at 80 °C. The double‐coupling reaction gave multisubstituted naphthalenes in good to high yields. Annulation of 1,2‐bis(pinacolatoboryl)arenes with bromo(bromoethenyl)arenes in the presence of a catalyst system that consisted of [Pd₂(dba)₃] (dba=dibenzylideneacetone) and 2‐dicyclohexylphosphino‐2′,6′‐dimethoxybiphenyl (SPhos) under the same conditions produced fused phenanthrenes in good to high yields. The first annulation coupling occurred regiospecifically at the bromoethenyl moiety. This procedure is applicable to the facile synthesis of polysubstituted anthracenes, benzothiophenes, and dibenzoanthracenes through a double annulation pathway by using the corresponding dibromobis[(Z)‐2‐bromoethenyl]benzenes as diboryl coupling partners.     

Cp2ZrCl2‐catalyzed synthesis of 2‐substituted quinozolin‐4(3H)‐ones

Zirconocene dichloride (Cp₂ZrCl₂) in the presence of DMF was found to be a highly efficient catalyst for the synthesis of structurally diverse 2‐substituted quinozolin‐4(3H)‐ones by reaction of anthranilimide with a wide range of aryl aldehydes. Copyright © 2013 John Wiley & Sons, Ltd.     

Silica‐Bound 3‐{2‐[Poly(ethylene Glycol)]ethyl}‐Substituted 1‐Methyl‐1H‐imidazol‐3‐ium Bromide: A Recoverable Phase‐Transfer Catalyst for Smooth and Regioselective Conversion of Oxiranes to β‐Hydroxynitriles in Water

A series of β‐hydroxynitriles were efficiently synthesized from the regioselective ring opening of oxiranes by cyanide anion in the presence of silica‐bound 3‐{2‐[poly(ethylene glycol)]ethyl}‐substituted 1‐methyl‐1H‐imidazol‐3‐ium bromide (SiO₂? PEG? ImBr) as a novel recoverable phase‐transfer catalyst in H₂O (Scheme 1 and Table 2). The workup procedure was straightforward, and the catalyst could be reused over four times with almost no loss of catalytic activity and selectivity.     

Syntheses of 2‐Unsubstituted 1H‐1,3‐Benzazaphospholes from N‐Formyl‐2‐bromoanilides

The phosphonylation of 2‐bromo‐formylanilides 1 with triethyl phosphite in the presence of preformed Pd(0)(triethyl phosphite)_n catalyst furnished 2‐phosphono‐formanilides 2 in good yields. Reduction with excess LiAlH₄ provided mainly N‐methyl‐2‐phosphinoanilines 3 and minor amounts of 1,2‐unsubstituted benzazaphospholes 4 . N‐Methyl‐1,3‐benzazaphospholes 5 were synthesized by the cyclocondensation of 3 with dimethylformamide dimethylacetal (DMFA). A more convenient route to 5 , avoiding the chromatographic separation of 4 , is the reduction of 1 to 2‐bromo‐N‐methylaniline 6 , followed by phosphonylation to 7 , LiAlH₄ reduction, and cyclization with DMFA. The coordination properties at σ²P of benzazaphospholes are characterized by structural data obtained by the crystal structure analysis of ( 5b )W(CO)₅.     

An Efficient One‐Pot Synthesis of 7,7‐Dimethyl‐2‐(2‐oxo‐2H‐chromen‐3‐yl)‐4‐aryl‐7,8‐dihydroquinolin‐5(6H)‐one Derivatives Using Chitosan–SO3H as Biodegradable Organocatalyst

Chitosan sulfonic acid (CS–SO₃H), a biodegradable green catalyst, was found to be an impressive system for one‐pot four‐component reaction of different aromatic aldehydes, 3‐acetylcoumarin, dimedone, and ammonium acetate leading to 7,7‐dimethyl‐2‐(2‐oxo‐2H‐chromen‐3‐yl)‐4‐aryl‐7,8‐dihydroquinolin‐5(6H)‐one under solvent‐free condition. This methodology produces diverse superiorities such as operational simplicity, short reaction time, and high yield. Further, the catalyst can be reused for four times without any noticeable decrease in the catalytic activity.     

Highly efficient AgNO3‐catalyzed approach to 2‐(benzo[d]azol‐2‐yl)phenols from salicylaldehydes with 2‐aminothiophenol, 2‐aminophenol and benzene‐1,2‐diamine

A new, convenient and efficient AgNO₃‐catalyzed strategy for the preparation of 2‐(benzo[d]azol‐2‐yl)phenol derivatives in good to excellent yields (63–98%) is described. The reaction proceeds via condensation/intramolecular nucleophilic addition/oxidation process between substituted salicylaldehydes and 2‐aminothiophenol, 2‐aminophenol or benzene‐1,2‐diamine under mild reaction conditions. Notably, this reaction utilizes cheap AgNO₃ as a readily available and low‐cost benign oxidant at low catalyst loadings with excellent functional group tolerance.     

Selective Synthesis of 2‐Aryl‐1‐benzylated‐1H‐benzimidazoles

An efficient and simple procedure was developed for the green synthesis of various 2‐aryl‐1‐ben‐zylated‐1H‐benzimidazoles in high yields by condensation of o‐phenylenediamine with aldehydes with P₂O₅/SiO₂ as catalyst under solvent‐free and ambient conditions.     

Microwave‐Assisted Expedite Synthesis of 2‐Phenylimidazo[1,2‐a]pyridylquinoxalin‐2(1H)‐ones

An efficient methodology has been developed for the synthesis of quinoxalin‐2(1H)‐one derivatives of 2‐phenylimidazo[1,2‐a]pyridines by microwave‐irradiated Hinsberg heterocyclization between 2‐phenylimidazo[1,2‐a]pyridine‐3‐glyoxalates and o‐phenylenediamine using either montmorillonite K‐10 or Yb(OTf)₃ as catalysts. Montmorillonite K‐10 was proven to be an efficient catalyst for the heterocyclization reaction between sterically hindered glyoxalate and o‐phenylenediamine only under microwave conditions. The use of Yb(OTf)₃/tetrahydrofuran was also found to be an effective catalyst for the above chemical transformation among a series of Lewis acids screened under microwave conditions; however, comparatively lesser yields were obtained as compared with the use of montmorillonite K‐10.     

Copper‐supported β‐cyclodextrin‐functionalized magnetic nanoparticles: Efficient multifunctional catalyst for one‐pot ‘green’ synthesis of 1,2,3‐triazolylquinazolinone derivatives

The green synthesis of 2‐(4‐((1‐phenyl‐1H‐1,2,3‐triazol‐4‐yl)oxy)phenyl)quinazolin‐4(3H)‐one derivatives is reported. The catalyst for this synthesis is copper‐supported β‐cyclodextrin‐functionalized magnetic silica–iron oxide nanoparticles ([Cu@BCD@SiO₂@SPION]). [Cu@BCD@SiO₂@SPION] simultaneously catalyses ‘click’ reaction, oxidation of C? N bond and multicomponent reaction. The desired 1,2,3‐triazolylquinazolinone product is easily obtained in water at room temperature under mild reaction conditions. Another advantage of the catalyst is its reusability. It can simply be isolated using an external magnet and reused in reactions with no significant decrease in catalyst efficiency. Transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometry and Fourier transform infrared spectroscopy are used for exact characterization of the [Cu@BCD@SiO₂@SPION] catalyst.     

Eco‐friendly synthesis of 3,4‐dihydroquinoxalin‐2‐amine,diazepine‐tetrazole and benzodiazepine‐2‐carboxamide derivatives with the aid of MCM‐48/H5PW10V2O40

A heterogeneous material composed of MCM‐48/H₅PW₁₀V₂O₄₀ was produced and used as an efficient, eco‐friendly and highly recyclable catalyst for the one‐pot and multicomponent synthesis of 3,4‐dihydroquinoxalin‐2‐amine, diazepine‐tetrazole and benzodiazepine‐2‐carboxamide derivatives in aqueous media and at room temperature with high yields in short reaction times (40–60 min). The recoverable catalyst was easily recycled at least five times without any loss of catalytic activity. The structures of obtained products were confirmed using ¹H NMR and ¹³C NMR spectra.     

Cationic organotin cluster [t‐Bu2Sn(OH)(H2O)]22+2OTf−‐catalyzed one‐pot three‐component syntheses of 5‐substituted 1H‐tetrazoles and 2,4,6‐triarylpyridines in water

The cationic organotin cluster [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? is easy to prepare and stable in air. The catalytic activity of [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? as a neutral organotin Lewis acid catalyst is probed through the one‐pot three‐component syntheses of 5‐substituted 1H‐tetrazoles from aldehydes, hydroxylamine hydrochloride and sodium azide, and of 2,4,6‐triarylpyridines from aromatic aldehydes, substituted acetophenones and ammonium acetate. The reactions proceed well in the presence of 1 mol% of [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? in water and provide the corresponding 5‐substituted 1H‐tetrazoles and 2,4,6‐triarylpyridines in good to excellent yields. The method reported has several advantages such as the catalyst being neutral, low catalyst loading and use of water as a green solvent.     

An efficient protocol for the one‐pot synthesis of 4‐(2‐(4‐bromophenyl)‐1,2,3‐triazol‐4‐yl)‐3,4‐dihydropyrimidin‐2(1H)‐ones/thiones catalyzed by Mg(NO3)2

A series of novel 4‐(2‐(4‐bromophenyl)‐1,2,3‐triazol‐4‐yl)‐3,4‐dihydropyrimidin‐2(1H)‐ones/thiones were prepared by condensing 2‐(4‐bromophenyl)‐4‐formyl‐1,2,3‐triazole with 1,3‐dicarbonyl compound and urea or thiourea using Mg(NO₃)₂ as an efficient and cheap catalyst. The satisfactory results were obtained with excellent yields and short reaction time. J. Heterocyclic Chem., (2010).     

SiO2 Nanoparticle‐catalyzed Facile and Efficient One‐pot Synthesis of N‐alkyl‐2,5‐bis[(E)‐2‐phenylvinyl]‐1,3‐dioxol‐4‐amine Under Solvent‐free Conditions

1,3‐Dioxole‐4‐amine derivatives have been prepared efficiently in one‐pot reaction using nanosized SiO₂ as a heterogeneous catalyst. The present method does not involve any hazardous organic solvents or catalysts. The high surface‐to‐volume ratio of SiO₂ nanoparticle has promising features for the reaction response such as the short reaction time, good to excellent yields, easy of operation and work‐up procedure, and purification of products by non‐chromatographic methods.     

Synthesis and In Vitro Antibacterial Activities of Novel 2‐Aryl‐3‐(phenylamino)‐2,3‐dihydroquinazolin‐4(1H)‐one Derivatives

An efficient synthesis of novel 2‐aryl‐3‐(phenylamino)‐2,3‐dihydroquinazolin‐4(1H)‐one derivatives using KAl(SO₄)₂.12H₂O (Alum) as a catalyst from an aldehyde and 2‐amino‐N‐phenylbenzohydrazine in ethanol is described. All synthesized derivatives were screened for anti‐bacterial activity. Some compounds exhibited promising anti‐bacterial activity with reference to standard antibiotics.     

Synthesis,Characterization, and Crystal Structure of a Polymeric Copper(II) Complex Derived from 2‐(5‐Chloro‐2‐hydroxybenzylideneamino)‐2‐ethylpropane‐1,3‐diol with Catalytic Oxidation Property

The copper(II) complex [Cu₂L₂(μ_1,3‐NCS)₂]_n · nMeOH [HL = 2‐(5‐chloro‐2‐hydroxybenzylideneamino)‐2‐ethylpropane‐1,3‐diol] was synthesized and characterized by elemental analysis, as well as FT‐IR, and UV/Vis spectroscopy. The structures of the ligand and the complex were confirmed by single‐crystal X‐ray diffraction analyses. The Schiff base ligand coordinates to the copper atoms through the phenolate oxygen and imino nitrogen atoms, and one hydroxyl oxygen atom. The copper atoms are in octahedral coordination. The complex is an active catalyst for the oxidation of cyclooctene and styrene with tert‐butylhydroperoxide as the oxidant under mild conditions.     

Pd‐Catalyzed Cycloisomerization of 4‐Aza‐1,6‐enynes to 3‐Aza‐bicyclo[4.1.0]hept‐2‐enes

A method for the synthesis of bicyclo[4.1.0]heptenes from 1,6‐enynes through Pd‐catalyzed cycloisomerization has been developed. N‐ and O‐tethered 1,6‐enynes were successfully transformed to their corresponding 3‐aza‐ and 3‐oxabicyclo[4.1.0]heptenes in reasonable‐to‐high yields using the catalysts [PdCl₂(CH₃CN)₂]/P(OPh)₃ or [Pd(maleimidate)₂(PPh₃)₂] in toluene. The computational calculations using density functional theory indicate that [PdCl₂{P(OPh)₃}] in the oxidation state Pd^II acts as the active catalyst species for the formation of 3‐azabicyclo[4.1.0]heptenes through 6‐endo‐dig cyclization.