A simple and efficient synthesis of gem-dihydroperoxides from ketones using aqueous hydrogen peroxide and catalytic ceric ammonium nitrate

Ketones were efficiently converted into the corresponding gem-dihydroperoxides in high yields within a short period of time on treatment with aqueous H₂O₂ (50%) in the presence of a catalytic amount of CAN in acetonitrile at room temperature.     

A novel and facile synthesis of 2-(cyclohexylamino)-6,7-dihydro-3-aryl-1H-indole-4(5H)-ones via a one-pot multi-component reaction

A simple and efficient synthesis of 2-(cyclohexylamino)-6,7-dihydro-3-aryl-1H-indole-4(5H)-ones was achieved via a one-pot multi-component reaction of cyclohexyl isocyanide, an aldehyde, a 1,3-dicarbonyl compound, and ammonium acetate in the presence of a catalytic amount of KHSO₄ in acetonitrile.     

An efficient aerobic oxidative aromatization of Hantzsch 1,4-dihydropyridines and 1,3,5-trisubstituted pyrazolines

4-Substituted Hantzsch 1,4-dihydropyridines and 1,3,5-trisubstituted pyrazolines were oxidized to the corresponding pyridines and pyrazoles, respectively, in high yields by molecular oxygen in the presence of catalytic amount of N-hydroxyphthalimide (NHPI) and Co(OAc)₂ in acetonitrile at room temperature.     

Catalytic nucleophilic activation of acetonitrile via a cooperative catalysis of cationic Ru complex, DBU, and NaPF6

The development of an efficient catalytic system for the direct addition of acetonitrile under mild amine basic conditions is described. A cooperative catalysis of CpRu complex, DBU, and NaPF₆ enables chemoselective and catalytic generation of nucleophiles from barely acidic acetonitrile, which is integrated into the addition to aldehydes, imines, and activated ketones. Mechanistic investigations revealed that the three catalyst components work together to achieve high catalytic efficiency.     

Effects of solvent and base on the palladium-catalyzed amination: PdCl2(Ph3P)2/Ph3P-catalyzed selective arylation of primary anilines with aryl bromides

A readily accessible catalytic system, PdCl₂(Ph₃P)₂/Ph₃P, was developed for the selective arylation of primary anilines with aryl bromides. The strong influence of solvents and bases on the catalytic activity was observed. In refluxing o-xylene, triphenylphosphine shows high efficiency for Pd-catalyzed intermolecular amination reactions. By changing the bases, mono- and diarylation of primary amines could be selectively achieved in high yields. Moreover, the catalytic system showed good toleration for the steric hindrance of anilines. A series of N,N,N′,N′-tetraaryl-1,1′-biphenyl-4,4′-diamines, important intermediates of OLED hole transport materials, were synthesized facilely via coupling reactions between 4,4′-diaminobiphenyls and aryl bromides.     

A new catalytic system for the copolymerization of dicyclopentadiene with CO: PdCl2/phen/M(CF3SO3)n

A new three-component catalytic system, PdCl₂/phen/M(CF₃SO₃)_n, was studied in the copolymerization of dicyclopentadiene (DCPD) with CO. It was found that the PdCl₂/phen/CF₃SO₃H catalytic system gave a very low catalytic activity, and the PdCl₂/phen/M(CF₃SO₃)_n catalytic system exhibited high activity when M(CF₃SO₃)_n was introduced instead of CF₃SO₃H. The resultant cooligomer was analyzed using various techniques such as FT-IR, ¹H NMR, ¹³C NMR, DSC and TGA. The results indicated that the copolymer was a polyspiroketal (PS) of CO and DCPD. Due to the tension of the ring of DCPD, the degree of copolymerization is low and the degree of crystallinity is also not high. The effects of ligands, M(CF₃SO₃)_n, solvents, 1,4-benzoquinone/PdCl₂ molar ratio, and temperatures on the copolymerization have been discussed in detail. The results showed that this novel catalytic system exhibited highly efficient activity, especially when 1,10-phenanthroline (phen) was used as ligand and Cu(CF₃SO₃)₂ was used as cocatalyst. The corresponding reaction rate was 49 000 g PS/molPd h when the reaction was carried out at 60 °C and 3.0 MPa of CO. The weight average molecular weight (M_w) and the number average molecular weight (M_n) of the resultant cooligomer were 1180 g/mol and 564 g/mol, respectively.     

TPD study on Cr/MgO catalysts for acrylonitrile synthesis from acetonitrile and methanol

Summary The TPD technique was used to investigate the desorption behaviour of methanol and acetonitrile on the Cr/MgO catalyst prepared by an impregnation method. Catalytic properties of the Cr/MgO catalysts for acrylonitrile synthesis from acetonitrile and methanol were also studied. The catalytic activities are related to the dissociative desorption temperature of CH₃OH or CH₃CN on the catalysts.     

FeCl3-catalyzed propargylation of aromatic compounds with propargylic acetates

A new method for the synthesis of propargylated aromatic compounds is developed. The reaction was carried out at room temperature in the presence of a catalytic amount of FeCl₃ in acetonitrile, high product yields were obtained with excellent regioselectivity and the reaction proceeded smoothly without exclusion of moisture or air.     

Study on Fe/MgO catalysts for acrylonitrile synthesis from acetonitrile and methanol

A series of Fe/MgO catalysts were prepared and used for acrylonitrile synthesis from acetonitrile and methanol. The catalysts were characterized by means of XRD, CO₂-TPD and CH₃OH-TPD. The Fe/MgO catalysts exhibit high catalytic activity and selectivity to acrylonitrile, which is due to the combined effect of Fe and MgO. This revised version was published online in August 2006 with corrections to the Cover Date.     

BF3·OEt2-catalyzed tandem Prins Friedel-Crafts reaction: a novel synthesis of sugar fused diarylhexahydro-2H-furo[3,2-b]pyrans

d-Glucose based homoallylic alcohol reacts smoothly with various aldehydes in the presence of arenes and a catalytic amount of BF₃·OEt₂ under mild conditions to afford a novel series of 5,7-diaryl-hexahydro-2H-furo[3,2-b]pyrans in good yields with high cis-selectivity.     

Co-catalyzed reductive cyclization of azido and cyano substituted α,β-unsaturated esters with NaBH4: enantioselective synthesis of (R)-baclofen and (R)-rolipram

Sodium borohydride in combination with a catalytic amount of CoCl₂ has been found to be an excellent catalytic system in reductive cyclizations of suitably substituted azido and cyano groups of α,β-unsaturated esters to afford γ and δ-lactams in high yields. The process has been demonstrated for the enantioselective synthesis of (R)-baclofen, (R)-rolipram, and (R)-4-fluorophenylpiperidinone, a key intermediate for (−)-paroxetine.     

AlCl3-NaI(NaBr)-t-BuOH: mild, chemo- and stereoselective reagents for hydrohalogenation of propiolic derivatives

(Z)-β-Iodo-propenamides and -β-iodo-propenoic esters were selectively prepared in high yields, at room temperature, through reaction of 2-propynamides and 2-propynoic esters, respectively, with AlCl₃ and NaI in the presence of t-BuOH in dichloromethane. These experimental conditions are compatible with the presence of acid sensitive acetal groups. Alternative use of EtOH or H₂O in place of t-BuOH was investigated. (Z)-Bromo-propenamides and corresponding esters were prepared according to a similar procedure using sodium bromide in refluxing acetonitrile.     

Mild and regioselective iodination of aromatic compounds with N,N′-diiodo-N,N′-1,2-ethanediylbis(p-toluenesulphonamide)

N,N′-Diiodo-N,N′-1,2-ethanediylbis(p-tolouenesulphonamide) [NIBTS] and catalytic trifluoroacetic acid can be used for the regioselective iodination of aromatic compounds in acetonitrile under mild conditions in excellent yields.     

Sonogashira reaction on pyridinium N-heteroarylaminides

The reactivity of N-(5-iodopyridin-2-yl)aminide in a copper-free Sonogashira cross-coupling process is reported. The reaction proceeds on using PdCl₂(PPh₃)₂ and DABCO as the base under microwave irradiation in acetonitrile or water as solvents. The process can also be carried out by traditional heating in acetonitrile on using Pd(AcO)₂/DABCO with Cs₂CO₃.     

ZnCl2-catalyzed hydrodefluorination of gem-difluoromethylene derivatives with lithium aluminum hydride

Hydrodefluorination of gem-difluoromethylene derivatives with lithium aluminum hydride in the presence of a catalytic amount of ZnCl₂ in good to high yields was described. A possible mechanism is also suggested.     

InCl3 as an efficient catalyst for synthesis of oxazolines under thermal, ultrasonic and microwave irradiations

Efficient synthesis of 2-oxazolines by the reaction of nitriles with β-aminoalcohols using InCl₃ as catalyst under reflux conditions is reported. This catalyst can be successfully applied to the chemoselective conversion of dicyanobenzenes to their corresponding mono- and bis-oxazolines. The application of ultrasonic and microwave irradiation improved the yields and reduced the reaction times. Another advantage of this catalytic system is its ability to carry out large-scale reactions under ultrasonic and MW irradiations. Alkylnitriles such as acetonitrile was also converted to its corresponding 2-methyloxazoline in the presence of catalytic amounts of InCl₃.     

Unprecedented InCl3-catalyzed formation of cis-fused perhydrofuro[2,3-b]oxepines

2-Methylindole and its N-substituted derivatives react smoothly with 2,3-dihydrofuran (DHF) in the presence of a catalytic amount of InCl₃ under mild conditions to afford the corresponding 2-methyl-3-perhydrofuro[2,3-b]oxepin-4-yl-1H-indole derivatives in fairly good yields with high diastereoselectivity, while 3,4-dihydro-2H-pyran (DHP) affords exclusively 5,5-di(1H-3-indolyl)-1-pentanol derivatives in high yields under similar reaction conditions.     

Catalytic oxidation of primary aromatic amines with sodium periodate catalyzed by Mn(III)salophen complex supported on polystyrene-bound imidazole

The catalytic activity of Mn(III)salophen complex supported on polystyrene-bound imidazole, [Mn(salophen)Cl-PSI], was studied in the oxidation of primary aromatic amines in acetonitrile/water, using sodium periodate as an oxygen source. Amines were oxidized efficiently to their corresponding azo derivatives in the presence of this catalyst. The heterogeneous catalyst showed high stability and reusability in the oxidation reactions and could be reused several times without loss of its activity. The effect of different solvents was studied in the oxidation of p-toluidine and CH₃CN/H₂O was chosen as the solvent.     

Stereoselective glycosylation of endo-glycals by microwave- and AlCl3-assisted catalysis

α-2-Deoxyglycosides were synthesized in good to excellent yields by microwave-assisted reaction of endo-glycals with various O-nucleophiles in the presence of catalytic amount of AlCl₃. These glycosyl additions occurred with high α-stereoselectivity and were complete in 5-35 min in 65-93% yield.     

Pressure and Temperature Effects on the Molecular Rotation in Acetonitrile-Water Mixtures

NMR spin-lattice relaxation time (T ₁) measurements were performed for ¹⁴N of acetonitrile in acetonitrile (CH₃CN)—H₂O mixtures and for ²H of heavy water in CH₃CN—D₂O mixtures at 30°C up to 294.2 MPa together with those for ²H in CH₃CN—D₂O mixtures at 10 and 20°C under atmospheric pressure over the whole composition range of the mixtures. IR absorption spectra for CH₃CN—H₂O and CH₃CN—10 mol% HDO/D₂O mixtures were obtained at 30°C under atmospheric pressure. Densities and viscosities of CH₃CN—H₂O mixtures were also measured under high pressure. The rotational correlation times for D₂O [τ _c (D)] and acetonitrile [τ _c (N)] were determined from T ₁ measurements. Under atmospheric pressure, τ _c (D) exhibits a small maximum around 10 mol% of acetonitrile at each temperature, and the maximum position is almost independent of temperature. These results suggest that the dipole–dipole interaction between acetonitrile and water molecules plays an important role in determining the rotational motion of water molecules in the mixtures. This is supported by the variation of the peak for the bending vibration of water molecules with composition. The decreases in τ _c (D) and τ _c (N) at higher acetonitrile contents are ascribed to the formation of acetonitrile dimer, trimer, and oligomer aggregates. Except for τ _c (D) in the water-rich region, the pressure coefficients of τ _c (D) and τ _c (N) are positive which is understood as a simple compression effect. Furthermore, the composition of mixture at which τ _c (D) and τ _c (N) show a maximum shifted to higher acetonitrile content with increasing pressure. These results are discussed in terms of the pressure effect on the equilibria of acetonitrile monomers with the aggregates of acetonitrile in the mixtures.