Perchloric Acid–Doped Polyaniline as an Efficient and Reusable Catalyst for the Synthesis of 2-Substituted Benzothiazoles

2-Substituted benzothiazoles have been efficiently synthesized in good yields by the condensation reaction of o-aminothiophenol with aldehydes in the presence of a catalytic amount of perchloric acid–doped polyaniline (HClO₄/PANI). The low cost, simple recovery, and efficient reusability are remarkable characteristics of this catalyst.     

γ-Al2O3-Supported 12-Tungstosilicic Acid as an Efficient Heterogeneous Catalyst for the Synthesis of α-Aminonitrile

The multicomponent Strecker reaction using trimethylsilyle cyanide was performed in very short reaction times, and α-aminonitriles were prepared in excellent yields in the presence of a catalytic amount of alumina-supported tungstosilicic acid.     

Synthesis of Di- and Tri-Substituted Imidazole-4-carboxylates via PBu3-Mediated [3 + 2] Cycloaddition

Some new di- and trisubstituted imidazole-4-carboxylates were prepared from amidoacetic acids 3 in the present report. The key step to establish such imidazole-4-carboxylates stemmed from the PBu₃-mediated [3 + 2] cycloaddition between in situ–generated Δ2-oxazolinone 4 and ethyl cyanoformate6. Our results indicated that trisubstituted imidazoles 7–20 were afforded in better yields than those of disubstituted imidazoles 21–27.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

(NH4)3PW12O40 as an Efficient and Reusable Catalyst for the Synthesis and Deprotection of 1,1‐Diacetates

An efficient method for the synthesis of 1,1‐diacetates (acylals) from different aldehydes in the presence of (NH₄)₃PW₁₂O₄₀ and acetic anhydride under solvent‐free conditions at ambient temperature is achieved. Selective conversion of aldehydes was observed in the presence of ketones. The deprotection of acylals has also been achieved using (NH₄)₃PW₁₂O₄₀ in methanol. The catalyst was found to possess good activity and considerable level of reusability.     

Synthesis of Bicyclic Imidazoles via [2 + 3] Cycloaddition between Nitriles and Regioselectively Generated α-Imino Gold Carbene Intermediates

The cyclic α-imino gold carbene intermediate B is most likely generated in situ via regioselective nitrene transfer from an azido group to a tethered terminal alkyne in the presence of a gold catalyst and at ambient temperature. This highly electrophilic intermediate can react with a weakly nucleophilic nitrile, which is used as the reaction solvent, to deliver a bicyclic imidazole rapidly in an overall bimolecular [2 + 2 + 1] cycloaddition and in mostly serviceable yield. The competing intramolecular Huisgen reaction, although likely also catalyzed by gold, is minimized by using AuCl(3) as the catalyst.     

Unexpected Direct Synthesis of N-Vinyl Amides through Vinyl Azide–Enolate [3+2] Cycloaddition

The unexpected synthesis of industrially important N-vinyl amides directly from aldehydes and α,β-unsaturated N-vinyl amides from esters is reported. This reaction probably proceeds through an initial [3+2] azide–enolate cycloaddition involving a vinyl azide generated in situ. A survey of the reaction scope and preliminary mechanistic findings supported by quantum computational analysis are reported, with implications for the future development of atom-efficient amide synthesis. Intriguingly, this study suggests that (cautious) reevaluation of azidoethene as a synthetic reagent may be warranted.     

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.     

Sulfonic Acid Functionalized Nano Γ-Al2O3: a New,Efficient, and Reusable Catalyst for Synthesis of Thioamides

Abstract

Sulfonic acid functionalized nano γ-Al₂O₃ is easily prepared by the reaction of nano γ-Al₂O₃ with 1,3-propane sulfone. This reagent can be used as an eficient catalyst for the synthesis of thioamides. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered for several times.     

K5CoW12O40 · 3H2O: Heterogeneous Catalyst for the Strecker‐Type Aminative Cyanation of Aldehydes and Ketones

One‐step synthesis of α‐aminonitriles was successfully carried out by a three‐component condensation of aldehydes or ketones, amines, and potassium cyanide in the presence of a catalytic amount of K₅CoW₁₂O₄₀·3H₂O as an efficient, reusable, and nontoxic catalyst.     

Crystal structure and properties of H3[PMo12O40] · 3C2H6O

The title compound H₃[PMo₁₂O₄₀]· 3C₂H₆O was prepared and characterized by X-ray crystallography, its i.r. spectrum, cyclic voltammetry and e.s.r. spectra. The anion of the title compound is a Keggin-type heteropoly structure based upon a central PO₄ tetrahedron surrounded by 12 MoO₆ octahedra arranged in four groups of three edge-shared octahedra Mo₃O₁₃. Weak hydrogen bonds exist between the organic solvent molecules and the heteropoly anion. The catalytic activity of the title compound was determined by the synthesis of butyl acetate. The conversion of n-BuOH reached 93.3% and the yield of MeCO₂Bu-n was 92.0% when the ratio of MeCO₂H to n-BuOH, catalyst amount, reaction time, reaction temperature were 2:1, 0.24% of the reactants (50 mg), 2.0 h and 115 120 °C, respectively.     

A Clean and Expedient Synthesis of Pyrido[1,4]oxazepino Spiropyrrolidines Through One-Pot,Three-Component [3 + 2] Cycloaddition Reaction

One-pot three component synthesis of novel pyrido[1,4]-oxazepine fused spiropyrrolidines has been accomplished in good yields by 1,3-dipolar cycloaddition reaction of azomethine ylide, derived from paraformaldehyde and sarcosine with (E)-4-benzylidene-hexahydro-1H-pyrido[2,1-c][1,4]-oxazepine-3(7H)-one as dipolarophiles derived from Baylis-Hillman adducts. The effect of solvent on the [3 + 2]-cycloaddition reaction is also studied.     

Synthesis and Characterization of a One- dimensional Molybdenum Oxide （H2enMe）[Mo3O10]

A hybrid organic-inorganic material (H2enMe)[Mo3O10] (C3H12Mo3N2O10, Mr = 523.97) has been synthesized under hydrothermal conditions and its crystal structure was determined by X-ray diffraction. It crystallizes in the orthorhombic system, space group Pnma with a = 12.430(2), b = 7.6089(12), c = 11.9553(19) , V = 1130.7(3) 3, Dc = 3.078 g/cm3, Z = 4, μ(MoKa) = 3.328 mm1, F(000) = 1000, the final R = 0.0256 and wR = 0.0716 for 1314 observed reflections with I > 2σ(I). A total of 11780 reflections were measured and 1325 were unique (Rint = 0.0244). It consists of infinite one-dimensional edge-sharing MoO6 octahedral chains with [Mo3O10]2 moieties. The protonated diaminopropane cations are located between the chains and linked to the oxygen atoms of the inorganic skeletal backbones by hydrogen bonds. It is indicated that the as-synthesized compound displays photochromic property in the solid state.     

Lacunary Derivative [HPW9O34]8− as Reusable and Active Catalyst for Alcohol Oxidation in Water

Abstract

An effective and reusable catalytic system for the oxidation of alcohols was developed based on ?-Na₈HPW₉O₃₄. The oxidation was conducted in water using hydrogen peroxide as oxidant. Good yields of ketones were obtained in oxidation of secondary alcohols, and the catalyst was recycled 10 times without obvious loss in activity.     

[α‐PW12O40]3− Immobilized on Ionic Liquid–Modified Polymer as a Heterogeneous Catalyst for Alcohol Oxidation with Hydrogen Peroxide

Ionic liquid–modified polystyrene resin beads were demonstrated to be an appropriate support for polyoxometalate. In this heterogeneous catalytic system, alcohols can be efficiently oxidized to corresponding carbonyl groups with H₂O₂ in CH₃CN. The catalyst can be easily recovered by filtration and recycled without apparent loss of catalytic performance.     

KAl(SO4)2 · 12H2O as a Recyclable Lewis Acid Catalyst for Synthesis of Some Amidoalkyl Naphthols Under Solvent-Free Conditions

A general and practical one-pot synthesis of amidoalkyl naphthols derivatives using KAl(SO₄)₂ · 12H₂O as catalyst is described. This method provides several advantages such as short reaction times, good yields, and simple workup procedure.     

New Synthesis of 2,4,6,8-Tetramethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione Using Etidronic Acid as a “Green” Catalyst

Russian Journal of Organic Chemistry - A new method has been developed for the synthesis of 2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione in 62% yield using etidronic acid...     

Hybrid Tungstocuprate [Cu(2,2'-bpy)3]2H4[CuW12O40]·6H2O Based on Keggin Polyoxoanion [CuW12O40]6-with CuⅡas Heteroatom

A novel hybrid tungstocuprate(Ⅱ) [Cu(2,2'-bpy)3]2H4[CuW12O40]·6H2O(2,2'-bpy=2,2'-bipyridine) was synthesized via hydrothermal method and characterized using elemental analyses, IR, UV, XPS, TG-DSC, EPR, and X-ray single crystal diffraction. The structural analysis shows that the complex consists of an unusual Keggin-type polyoxoanion [CuW12O40]6- and a pair of chiral complex cations [Cu(2,2'-bpy)3] together with four protons and six crystallization water molecules, and the Keggin polyoxoanion is connected with [Cu(2,2'-bpy)3] via multiple C-H…O hydrogen bonds resulting in a dimer.     

Synthesis and Characterization of a New Cyclotriphosphate [C8H 11 NH 3 ] 3 P 3 O 9 ·3H 2 O

Among the various categories of phosphates, the number of organic cation cyclotriphosphates remains limited. In this work, we report the chemical preparation, crystal structure, thermal analysis, and spectroscopic investigations of a new cyclotriphosphate [C₈H₁₁NH₃]₃P₃O₉·3H₂O. It is characterized by X-ray diffraction, infrared spectroscopy, nuclear magnetic resonance, and thermal analysis. This compound is a triclinic P unit cell with the following parameters: a = 13.949(4), b = 9.867(3), c = 14.180(2) Å, α = 92.22(2), β = 119.27(2), γ = 85.10(10)°, V = 1696.1(8) Å ³ , and Z = 2. Its structure has been determined and refined to R = 0.041 and R_w = 0.062, using 4527 independent reflections. The atomic arrangement can be described by corrugated thick layers built by [P₃O₉]^3- anions, ammonium groups, and water molecules. The organic entities are located between these layers. H-bonds connecting the different species play an important role in the tridimensionnal network cohesion. This compound is also characterized by infrared spectroscopy, nuclear magnetic resonance, and thermal analysis.     

Synthesis, crystal structure, and thermal analysis of hexahydrogen dodecavanadate of composition [NH3 · H2O]6 · H6[Ca4V12O40] · 6H2O

Dihydrogen dodecavanadate of composition [NH₃ · H₂O]₆ · H₆[Ca₄V₁₂O₄₀] · 6H₂O was synthe-sized and studied by X-ray crystallography and TGA analyses. The crystals are cubic, space group I $\bar 4$ 3m;; unit cell parameters: a = 13.518(2) ?, V = 2470.4(3) ?³, ??_calc = 2.2334 g/cm³, Z = 2.