Efficient Room-Temperature Synthesis and Antimicrobial Study of Novel 2-Aroylbenzofuran-3-ols from Substituted Methyl Salicylates and Phenacyl Bromides

The article describes a convenient and efficient synthetic route for the construction of 2-aroylbenzofuran-3-ols from readily available diverse methyl salicylates and phenacyl bromides using K₂CO₃ as catalyst in dimethylformamide as solvent at room temperature. The reaction involves two steps, which occur in quick succession within 1 h to deliver the product with reasonably high yields. All the synthesized 2-aroylbenzofuran-3-ols (4a–u) were subjected for their antimicrobial studies, and some of these have shown prominent activity.

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Novel Four-Step Synthesis of Thioxo-quinazolino[3,4-a]quinazolinone Derivatives

A novel synthesis of thioxo-quinazolino[3,4-a]quinazolinone framework was developed through a four-step reaction starting from isatoic anhydride. The resulting 2-aminobenzamides from the reaction of isatoic anhydride and different amines underwent coupling–cyclization reaction with 2-nitrobenzaldehydes, reduction of nitro group, and then cyclization reaction with carbon disulfide (CS₂). All steps were carried out under easy and user-friendly conditions in a short time without using expensive catalysts or reagents.

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One-Pot Microwave-Assisted Synthesis of 3,4-Disubstituted 2-Quinolinones

An improved one-pot synthesis of 3,4-disubstituted 2-quinolinones is described. The condensation of substituted 2-aminobenzophenone (or 2-aminophenyl alkyl ketone) with acid chlorides was carried out in the presence of triethylamine (or NaH) under microwave reaction conditions (150oC, 200 psi). The reactions were completed within minutes to produce 2-quinolinones in moderate to excellent yields and good purities.

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Synthesis of β-Aryl-β-sulfanyl Ketones by a Sequential One-Pot Reaction Using KF/Al2O3 in Glycerol

The title compounds were synthesized by a sequential one-pot reaction of aryl aldehydes, aryl-methyl ketones, and thiols promoted by KF/Al₂O₃. This methodology affords a large number of β-aryl-β-sulfanyl ketone derivatives from aliphatic and aromatic thiols in good yields and is also applicable for solid substrates.

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Free Radical–Mediated Chemoselective Reduction of Enones

A novel methodology has been devised for the chemoselective reduction of enones involving the use of ⁿ Bu₃SnH and azobisisobutyronitrile. The 1,4-reduction of variously substituted α,β-unsaturated cyclic and acyclic enones has been successfully carried out under free radical reaction conditions. The reaction has been determined to proceed via single-electron transfer.

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CuFe2O4 Nanoparticles: A Magnetically Recoverable and Reusable Catalyst for the Synthesis of Coumarins via Pechmann Reaction in Water

The synthesis of coumarins by hydroxyalkylation of phenols with ethyl acetoacetate (via Pechmann reaction) is attempted using magnetically separable and reusable CuFe₂O₄ nanoparticles in water.

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Optimization of Microwave-Assisted Michael Addition Reaction Catalyzed by L-Proline in Ionic Liquid Medium Using Response Surface Methodology

Michael addition reactions of aldehyde to β-nitrostyrene catalyzed by L-proline were investigated by using controlled, monomode microwave-assisted technique in a closed vessel system. Ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim]NTf₂) was used as the reaction medium to replace the commonly used volatile organic solvents and as a good absorbing solvent during Michael reaction under the influence of microwave irradiation. The Michael product is clean and generates good yields in short reaction times with moderate results on enantioselectivity (ee). In this work, optimization of proline-catalyzed Michael reaction was carried out using response surface methodology (RSM) based on a three-factor-three-level central composite design (CCD). Various reaction parameters including catalyst loading (5–30 mol%), reaction time (5–40 min), and substrate (2–5 equivalent ratio) were investigated. A high Michael yield (96.5%) with 36.9 ee% was obtained at the optimum conditions of 10.0 mol% catalyst loading, 5.0 min reaction time, and 2.0 substrate equivalent ratio.

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Boric Acid–Catalyzed One-Pot Access to 7-Aryl-benzopyrano[4,3-b] benzopyran-6,8-diones Under Aqueous Micellar Conditions

A mild protocol for the synthesis of 7-arylbenzopyrano[4,3-b]benzopyran-6,8-diones by three-component reaction of 4-hydroxycoumarin, aromatic aldehyde, and 5,5-dimethylcyclohexane-1,3-dione (dimedone) with boric acid catalyst under aqueous micellar conditions is described. Good to excellent yield, high selectivity, tolerance of several common functional and protecting groups, and green features including avoidance of organic solvent in the reaction as well as isolation stage and use of nontoxic water-compatible mild Lewis acid catalyst are key attractive features of the protocol.

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Highly Stereoselective Cyclopropanation of Olefins Catalyzed by a Novel C 3-Symmetric Arsine

A novel C ₃-symmetric arsine was employed in the one-pot cyclopropanation of olefins with carbonyl-stabilized arsonium ylides formed in situ from phenacyl bromide in the presence of NaHCO₃. This new arsine demonstrates good stereoselectivity and activity in the one-pot cyclopropanation of arylidenemalononitrile.

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Efficient Deallylation of Allyl Phenyl Ethers by Molecular Iodine in PEG-400 and Their Utility for Flavone Synthesis

Rapid and efficient deallylation of allyl phenyl ethers by molecular iodine (20 mol%) in polyethylene glycol-400 at 60 °C has been reported. This method has short reaction time, readily available catalyst, and reuse of reaction medium with good yield. The utility of this methodology has been extended to flavone synthesis.

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Application of Hantzsch Dihydropyridine in Copper-Catalyzed [3 + 2] Cycloaddition of Terminal Alkynes with Azides

2,6-Dimethyl-3,5-bis(ethoxycarbonyl)-1,4-dihydropyridine (dihydropyridine Hantzsch ester, DHPHE) and CuSO₄ · 5H₂O efficiently accelerated azide–alkyne cycloaddition reactions of both aliphatic and aromatic substrates and gave 1,4-disubstituted 1,2,3-triazoles as the only isomer in good to excellent yields at room temperature with 1 mol% of CuSO₄ · 5H₂O/DHPHE (1:1 in molar ratio). The reaction could be carried out smoothly in methanol in air with high efficiency. DHPHE may play multiple important roles in the reaction: a reducing reagent to generate the catalytic center copper(I) from CuSO₄, a base to help form the intermediate acetylide, and a ligand to stabilize the catalytic copper(I) species via coordination after being transformed to pyridine derivative.

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Synthesis of Bisindolylindeno[1,2-b]quinoxaline and Bisindolylindeno[3,4-b]pyrazine with Poly(N,N′-dibromo-N-ethylnaphthyl-2,7-disulfonamide)

Poly(N,N′-dibromo-N-ethylnaphthyl-2,7-disulfonamide) (PBNS) as novel reagent was synthesized. Bisindolylindeno[1,2-b]quinoxaline and bisindolylindeno[3,4-b]pyrazine derivatives were synthesized in a simple and efficient method from the three-component condensation reaction of indole, indane-1,2,3-trione, and diamine aromatic compounds by PBNS under solvent-free conditions at 80 °C in good to excellent yields, short reaction times, and a simple procedure for new derivatives.

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Green and Reusable Synthetic Procedure for Pyridine N-Oxides Catalyzed by a Lacunary Polyoxometalate

A lacunary Keggin polyoxometalate of K₈[BW₁₁O₃₉H] · 13H₂O was used as an effective and reusable catalyst for pyridine oxidation. Good yields of pyridine N-oxides were obtained in this catalytic system with hydrogen peroxide in water under mild conditions.

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Facile One-Pot Synthesis of 1,2,3-Triazoles Featuring Oxygen,Nitrogen, and Sulfur Functionalized Pendant Arms

A practical and efficient one-pot synthesis of novel 1,2,3-triazoles featuring nitrogen, oxygen, and sulfur functionalized pendant arms has been developed. The click reaction of mono-propargyl derivatives supported by aniline, thiophenol, and benzyl alcohol, with sodium azide and p-substituted benzyl halogenides, renders a series of N-substituted-1,2,3-triazoles in good yields under mild reaction conditions. The catalyst system was based in Cu(OAc)₂ · H₂O, sodium L-ascorbate, and 1,10-phenanthroline monohydrate, and all reactions were performed in a mixture H₂O–ethanol (4:1 v/v). Additionally, the preparation of bis-1,2,3-triazoles supported by di-propargylated aniline was carried out, demonstrating the versatility of the present methodology.

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Mild,Selective Oxidation of Aromatic Alcohols Using β-Cyclodextrin-Functionalized Glass Microparticles: Characterization,Stability, and Application

The surface of glass microparticle (GMP) was functionalized with β-cyclodextrin (→ GMP-β-CD) and was characterized by x-ray photoelectron spectroscopy (XPS). GMP-β-CD was used to catalyze oxidation of alcohols into aldehydes and katones with excellent yield (86–92%). The modified surface of GMP-β-CD showed no change or degradation after repeated use as confirmed from XPS analysis after 10 cycles.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Trifluoroacetic Acid–Catalyzed Synthesis of N-(1-(3-Chlorophenyl)-3-aryl-3-oxopropyl)-2-(4-nitrophenyl)acetamides via Dakin–West Reaction

A series of novel N-(1-(3-chlorophenyl)-3-aryl-3-oxopropyl)-2-(4-nitrophenyl) acetamides were synthesized using p-nitrophenylacetonitrile, m-chlorobenzaldehyde, and aryl methyl ketones as starting materials and trifluoroacetic acid (TFA) as catalyst. This realized an improved Dakin–West reaction in which p-nitrophenylacetonitrile was involved. The chemical structures of up to 15 target molecules were characterized by ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry. This method provides a facile synthetic protocol under more moderate reaction conditions, smaller dosage (0.40 mol%) and hence lower cost of catalyst, and simpler posttreatment in comparison to other known methods. A reaction mechanism is proposed in which hydroxyacetophenone is first catalytically converted into the corresponding acetoxyacetophenone prior to be involved in the subsequent Dakin–West reaction that eventually leads to hydroxyl-acetylated target compounds.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Catalytic Microwave-Promoted Direct Aldol Condensation Using Resin-Bound Secondary Amine

A series of polystyrene-supported imino group-bearing catalysts were prepared. A highly efficient combination of recyclable catalysts and microwave irradiation was developed as a green protocol for the direct aldol reaction. Notably, microwaves greatly shorten the reaction times to only 20 min and improve the yield significantly. Catalyst loading was reduced as well. Different aromatic aldehydes as aldol donors were subjected to our catalyst system and afforded the corresponding products in satisfactory yields. Additionally, the polymer-supported catalysts could be recovered by simple filtration and were reusable for at least four times without significant loss of reactivity.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Solubility of sildenafil citrate in propylene glycol + water mixtures at various temperatures

The solubility of sildenafil citrate (SC) in aqueous mixtures of propylene glycol (PG) was investigated. This study was carried out at different mass fractions of PG ranging from 0.1 to 0.9 at T = 293.2–313.2 K. The solubility of SC in the mixed solutions increased with increasing temperature and PG mass fraction.

The solubility values were correlated by two co-solvency models (Jouyban–Acree model and van’t Hoff–Jouyban–Acree model). The mean relative deviations (MRD) were 5.7% and 5.5%, respectively. Density of the SC-saturated solutions over the entire solvent composition and temperature range was also measured and the results correlated with the Jouyban–Acree model. Furthermore, the apparent thermodynamic properties, dissolution enthalpy, dissolution entropy and Gibbs free energy change of dissolution process of SC in all the mixed solvents were calculated according to van’t Hoff and Gibbs equations. Dissolution of SC in these mixed solvents is an endothermic process.     

Novel,Recyclable, and Thermally Stable Task-Specific Ionic Liquid (TBA Acetate) Medium/Catalyst for the Synthesis of Indolylidinecyclic-1,3- and -1,4-diketones

A simple and efficient synthesis of indolylidinethiazolidnediones (3) and indolylidinecyclic-1,3-diketones (5) has been developed by reaction of indole-3-aldehyde (1) with thiazolidinedione (2) or cyclic-1,3-diketones (4) using tetra butyl ammonium acetate (TBAA) melt as novel, cost-effective, and recyclable ionic liquid under solvent-free green conditions at 100 °C for 15–20 min without additional use of catalyst.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Efficient Method for the Synthesis of α,α′-Bis(arylmethylidene) Cycloalkanones Catalyzed by Bromodimethylsulfonium Bromide

Bromodimethylsulfonium bromide (BDMS)–catalyzed crossed aldol condensation between aromatic aldehydes and ketones is reported to access α,α′-bis(arylmethylidene) cycloalkanones at room temperature in good yields within 3–10 min. The salient features of this method are the simplicity of the procedure, the ready accessibility of the catalyst, and greater yields in relatively short reaction times.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]