A new, efficient and simple method for the thionation of ketones to thioketones using P4S10/Al2O3

A simple, efficient and new method has been developed for the synthesis of thioketones by thionation of ketones using P₄S₁₀/Al₂O₃ in acetonitrile. It has been found that the P₄S₁₀/Al₂O₃ combination provides a simple and convenient method for the synthesis of thioketones.     

Efficient synthesis of xanthenedione derivatives using cesium salt of phosphotungstic acid as a heterogeneous and reusable catalyst in water

Cs_2.5H_0.5PW₁₂O₄₀ has been reported to be an efficient catalyst for the synthesis of 1,8-dioxo-octahydroxanthene from aldehydes and 1,3-cyclohexanedione/dimedone in water. This approach is environmentally benign with clean synthetic procedure, short reaction time, easy workup procedure, excellent yield, and regeneration of catalyst, which made this protocol efficient and safe.     

Regioselective Ring Opening of Styrene Oxide Catalyzed by MoO2(acac)2

The ring-opening reaction of styrene oxide with various nitrogen, oxygen, and carbon nucleophiles catalyzed by MoO₂(acac)₂ was described. The corresponding ring-opening compounds with nearly 100% regioselectivities were obtained under mild conditions in moderate to good yields. MoO₂(acac)₂ is a highly efficient catalyst for the ring opening of styrene oxide. The reaction serves as a simple and efficient method for the synthesis of 1,2-bifunctional compounds.     

B2O3/Al2O3 as an Efficient and Recyclable Catalyst for the Synthesis of β-Amino Alcohols under Solvent-Free Conditions

A convenient and efficient procedure for the solvent-free synthesis of β-amino alcohols has been achieved via B₂O₃/Al₂O₃-promoted highly regioselective ring opening of epoxides with aromatic amines in good to excellent yields at room temperature. Additionally, the catalyst can be recycled without affecting the catalytic property.     

Ultrasound-promoted green approach for the synthesis of multisubstituted pyridines using stable and reusable SBA-15@ADMPT/H5PW10V2O40 nanocatalyst at room temperature

ABSTRACT

A facile one-pot protocol for the synthesis of 2-amino-3-cyanopyridins using SBA-15@Triazine/H₅PW₁₀V₂O₄₀ as an efficient catalyst under ultrasonic conditions has been developed. The nanohybrid catalyst was prepared by the chemical anchoring of Keggin heteropolyacid H₅PW₁₀V₂O₄₀ onto the surface of SBA-15 mesoporous silica modified with 2-APTS -4,6-bis(3,5-dimethyl-1H-pyrazol- 1-yl)-1,3,5-triazine (ADMPT) linker. Then the nanohybrid was used as a green, efficient, eco-friendly, and highly recyclable catalyst for the one-pot and multi-component synthesis of 2-amino-3-cyanopyridin derivatives from the reaction of aldehydes, malononitrile, cyclic ketones and ammonium acetate under ultrasound waves with good to excellent yields (79–95%) and in a short span of time. This nanocatalyst was characterized by using FT-IR, XRD, SEM, TEM, BET, and EDX techniques.     

One‐Pot Synthesis of Benzimidazoles from o‐Nitroanilines under Microwaves via a Reductive Cyclization

An efficient microwave irradiation synthesis of 2‐substituted benzimidazoles in one step via the Na₂S₂O₄ reduction of o‐nitroanilines in the presence of aldehydes is described. The method is simple and a good option to obtain the title compounds in a very short time.     

H6P2W18O62·18H2O–Catalyzed,Three-Component,One-Pot Synthesis of Indeno[1,2-b]quinoline-7-one Derivatives

In this work, a rapid and efficient one-pot method for the synthesis of indeno[1,2-b]quinoline-7-one derivatives by condensation of 1-naphthylamine, 1,3-indanedione, and different aldehydes in the presence of H₆P₂W₁₈O₆₂·18H₂O as a green and reusable catalyst in refluxing acetic acid is described.     

P2O5/SiO2 as a New,Efficient, and Reusable Catalyst for Preparation of β-Enaminones Under Solvent-Free Conditions

P₂O₅/SiO₂ (30% w/w) was applied as an efficient, heterogeneous, and reusable catalyst for the synthesis of β-enaminones. The reactions were rapidly completed at 80 °C under solvent-free conditions and products were obtained in good to excellent yields.     

(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.     

Silica-Supported LiHSO4 as a Highly Efficient,Mild, Heterogeneous,and Reusable Catalytic System for the Solvent-Free Synthesis of Bis(indolyl)methanes

Silica-supported LiHSO₄ (LiHSO₄/SiO₂) is used as a green, cheap, and efficient catalytic system for the synthesis of bis(indolyl)methanes via the condensation of indoles with carbonyl compounds under solvent-free conditions. The reactions proceed rapidly at room temperature, and the title compounds are obtained in high to excellent yields.     

An efficient synthesis of 5-substituted 1H-tetrazoles via B(C6F5)3 catalyzed [3+2] cycloaddition of nitriles and sodium azide

A simple and efficient protocol is developed for the synthesis of 5-substituted 1H-tetrazole derivatives from various nitriles and sodium azide (NaN₃) via [3+2] cycloaddition reaction using B(C₆F₅)₃ as a catalyst. The present synthetic method displayed significant advantages such as low catalyst loading, mild reaction conditions, low toxicity, easy work-up, high yields, and compatibility with other functional groups.     

Microwave-promoted efficient conversion of acetophenones to 1,3,5-triarylbenzenes catalyzed by H3PW12O40 and nano-silica supported H3PW12O40 as reusable catalysts

H₃PW₁₂O₄₀ and nano-silica supported H₃PW₁₂O₄₀ were found to be efficient heterogeneous catalysts for the preparation of 1,3,5-triarylbenzenes via triple self condensation of acetophenones under microwave irradiation and solvent-free conditions. High yields, short reaction times, easy work-up, easy availability and handling, eco-friendly and reusability of the catalysts are the main aspects of the present method. The catalytic mechanism of 1,3,5-triarylbenzenes synthesis is also proposed.     

Visible-light-mediated facile synthesis of disulfides using reusable TiO2/MoS2 nanocomposite photocatalyst

A nontoxic and inexpensive TiO₂/MoS₂ nanocomposite was prepared and employed as an efficient photocatalyst for the synthesis of symmetrical disulfides under visible light irradiation at room temperature. Both aryl and alkyl thiols survived the reaction conditions, affording the corresponding disulfides in good to excellent yields. The photocatalyst could be easily recovered by simple centrifugation and filtration and reused several times without significant loss in its activity.     

Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Using Ce(SO4)2-SiO2 as a Heterogeneous and Recyclable Catalyst

A simple and efficient synthesis of 3,4-dihydropyrimidinones or thiones is described, using silica-supported ceric sulfate [Ce(SO₄)₂-SiO₂] as a heterogeneous catalyst from an aldehyde, 1,3-dicarbonyl compound, and urea or thiourea at 110 °C under solvent-free conditions. Compared with the classical Biginelli reaction, this new method consistently has better yields, short reaction time, easy separation, and tolerance toward various functional groups.     

Ferric sulfate [Fe2(SO4)3·xH2O]: an efficient heterogeneous catalyst for the synthesis of tetrahydroquinoline derivatives using Povarov reaction

Fe₂(SO₄)₃·xH₂O can be used as an efficient and reusable catalyst for the synthesis of pyrano- and furanotetrahydroquinolines via one-pot three-component Povarov reaction involving aromatic aldehydes, aromatic amines, and cyclic enol ethers. The catalyst is recyclable, economically viable, and environmentally benign. This protocol provides good yields and diastereoselectivity as well as applicability on a wide range of substrates.     

A novel multi-component reaction of indole, formaldehyde, and tertiary aromatic amines

A novel multi-component reaction of indoles, formaldehydes, and tertiary aromatic amines is described for the synthesis of dialkylaminoarylated indoles using silica-supported perchloric acid (HClO₄-SiO₂) as an inexpensive and highly efficient catalyst. The key features of this multi-component reactions are operational simplicity, mild reaction conditions, regioselectivity, and recycling of catalyst.     

Silica-gel-supported Ce(SO4)2·4H2O-mediated cyclization of 2′-amino and 2′-hydroxychalcones under solvent-free conditions

A simple, efficient, and environmentally friendly approach for the synthesis of flavones, aza-flavones, and aza-flavanones from corresponding 2′-hydroxy or 2′-aminochalcones has been developed. The reactions are successfully conducted in presence of silica-gel-supported Ce(SO₄)₂·4H₂O under solvent-free conditions.     

Efficient and green synthesis of 4H-pyran derivatives under ultrasound irradiation in the presence of K2CO3 supported on acidic montmorillonite

Acid-treated montmorillonite coating with K₂CO₃ is used as a catalyst for an efficient, rapid, one-pot synthesis of 4H-pyran derivatives in good yield under ultrasonic irradiation. The catalyst is environmentally benign, easy handling, nontoxic, stable in air, and inexpensive.     

Fe（HSO4）3： An efficient,heterogeneous and reusable catalyst for the synthesis of 14-aryl- or alkyl- 14H-dibenzo[a,j]xanthenes

Fe（HSO4）3 has been used as an efficient and recyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14Hdibenzo[aj]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.     

Synthesis of 3,4-dihydropyridin-2-one derivatives in convergent mode applying bio catalyst vitamin B1 and polymer supported catalyst PEG-SO3H from two different sets of building blocks

Two highly efficient, green protocols have been developed for the synthesis of 3,4-dihydropyridin-2-one derivatives from different starting materials exploring two reaction specific catalysts, vitamin B₁ (VB₁), and PEG-SO₃H. VB₁ catalyzed simple and convenient protocol has been developed for the synthesis of 3,4-dihydropyridin-2-one derivatives by the installation of aldehyde, cyanoacetamide, and 1,3-dicarbonyl compounds. In addition, 3,4-dihydropyridin-2-one derivatives have also been synthesized by simply combining aldehyde, malononitrile, and 1,3-dicarbonyl compounds via the formation of 4H-pyran nucleus and PEG-SO₃H catalyzed one-pot rearrangement.