Efficient,Green, Solvent-Free Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones via Biginelli Reaction Catalyzed by Cu(NO3)2·3H2O

The synthesis of 3,4-dihydropyrimidin-2-(1H)-ones derivatives via a three-component Biginelli reaction using copper nitrate as a catalyst under solventless conditions is reported, providing a green, rapid, efficient, and convenient method for the preparation of Biginelli compounds in good yields.     

Solvent‐Free Aerobic Chemoselective Oxidation of β‐Ionone catalyzed by N‐Hydroxyphthalimide/Co(acac)2

β‐Ionone was oxidized with O₂ under solvent‐free conditions catalyzed by an N‐hydroxyphthalimide/Co(acac)₂ system in mild conditions with high conversion and excellent selectivity to oxo‐β‐ionone or 5,6‐epoxy‐β‐ionone in different reaction conditions, respectively.     

ZrOCl2 · 8H2O as an Efficient Reagent for the Solvent‐Free Synthesis of 3,4‐Dihydropyrimidin‐2‐(1H)‐ones

ZrOCl₂ · 8H₂O, a commercially available reagent, can be used for the promotion of the synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones under solvent‐free reaction conditions. All reactions were performed at 90°C in good to high yields.     

Convergent One‐Pot Synthesis of 3‐Substituted Quinazolin‐4(3H)‐ones under Solvent‐Free Conditions

A convenient method for the synthesis of 3‐substituted quinazolin‐4(3H)‐ones using the convergent reactions of formic acid, a primary amine, and isatoic anhydride under solvent‐free conditions and with brief microwave irradiation is described.     

SbCl3‐Al2O3–Catalyzed,Solvent‐Free,One‐Pot Synthesis of Benzo[b]1,4‐diazepines

This article explores the use of antimony(III) chloride adsorbed on neutral alumina as an efficient catalyst for the one‐pot synthesis of benzo[b]1,4‐diazepines (83–94%) under solvent‐free conditions. The process is easy, efficient, ecofriendly, and economical.     

Chemoselective and Solvent‐Free Thioacetalization of Aldehydes by a Catalytic Amount of NBS

A chemoselective, straightforward, and rapid method for thioacetalization of aldehydes by use of 1,2‐ethandithiol and a catalytic amount of N‐bromosuccinimide under solvent‐free conditions is reported. The reaction takes place in excellent yields and short reaction times.     

Dodecatungstophosphoric Acid (H3PW12O40): A Novel and Efficient Recyclable Catalyst for Synthesis of 1,1‐Diacetates from Aromatic Aldehydes in Solvent‐Free System and Their Deprotection

A facile and efficient method for the formation of 1,1‐diacetates from a variety of aldehydes in the presence of a catalytic amount of H₃PW₁₂O₄₀ and acetic anhydride was achieved in good yields at room temperature. The deprotection of the resulting acylals is achieved using the same catalyst in acetone.     

Solvent‐Free,One‐Pot Synthesis of Pyrano[2,3‐c]pyrazole Derivatives in the Presence of KF·2H2O by Grinding

Abstract

A solvent‐free, one‐pot process for the preparation of 4H‐pyrans in the presence of KF?·?2H₂O by grinding was achieved. Its advantages are easy workup, mild reaction conditions, high yields, and environmental friendliness.     

Facile One‐Pot Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐one Catalyzed by Zn(NH2SO3)2

An efficient synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones (DHPMS) from aromatic aldehydes, β‐keto ester, and urea (or thiourea) in refluxing ethanol using zinc sulfamate as a catalyst is first described here. Compared to the classical Biginelli reaction, this new method consistently has the advantages of good yields (76–96%), short reaction time (2–5 h), no corrosion of equipment, ease of manipulation, and low‐cost catalyst.     

A Solvent‐Free Procedure for Synthesis of N‐Sulfonylimines Using Microwave Irradiation Catalyzed by ZrO2/S2O8 2− Solid Superacid

Abstract

A solvent‐free synthesis of N‐sulfonylimines from aldehydes with sulfonamides is described using ZrO₂/S₂O₈ ^2? as catalyst under microwave irradiation. This method is fast and high yielding for a range of substrates.     

KHSO4 · H2O/SiO2‐Catalyzed,One‐Pot,Solvent‐Free Synthesis of Pyrazolines,Tetrahydrocarbozoles and Indoles using Microwave Irradiation

A new high‐yielding, operationally simple, solvent‐free, and mild method for preparation of pyrazolines, tetrahydrocarbazoles, and indoles has been developed using KHSO₄ · H₂O impregnated on SiO₂. The reactions have been probed under microwave irradiation (MWI), and ultrasonic and thermal conditions, employing different solid supports. The data revealed that KHSO₄ · H₂O impregnated on SiO₂ under MWI provides the best yields in a shorter time under solvent‐free reaction conditions.     

Solvent‐Free Synthesis of 3‐Amino‐2,4‐dicarbonitrile‐5‐methylbiphenyl by a Grinding Method

A convenient, environmentally friendly, and solvent‐free procedure has been developed for the synthesis of 3‐amino‐2,4‐dicarbonitrile‐5‐methylbiphenyl derivatives. Compared with the classical reaction condition, this new synthetic method has the advantages of excellent yields, easy setup, mild reaction conditions, and environmental friendlines.     

A Mild and Efficient Deprotection of Geminal Diacetates Catalyzed by FeCl3 ·6H2O in Ionic Liquid

The selective deprotection of geminal diacetates promoted by FeCl3·6H2O in the ionic liquid [bmim] [BF4] canbe efficiently achieved in good yields. The ionic liquid and the catalyst can be recycled easily and the process is car ried out under mild conditions.     

Cu(NO3)2 · 3 H2O as an Efficient Reagent for the Chemoselective Trimethylsilylation of Primary Alcohols and Oxidation of Trimethylsilyl Ethers

Abstract

Cu(NO₃)₂ · 3 H₂O can be used as an efficient reagent for the chemoselective trimethylsilylation of primary benzylic and aliphatic alcohols with hexamethyldisilazane (HMDS). This reagent is also able to oxidize the obtained trimethylsilyl ethers to the corresponding carbonyl compounds in the presence of wet SiO₂ and KBr. In this study, all reactions are performed in the absence of a solvent and good-to-high yields are obtained.     

Practical Synthesis of (S)‐(+)‐3‐Octanol by Lipase‐Catalyzed Enantioselective Acetylation

(S)‐(+)‐3‐Octanol (S)‐1 was prepared in high enantiomeric excess through catalyzed acetylation of racemic alcohol 1 by using lipase from Candida antarctica (Chirazyme L‐2) in the presence of vinyl acetate in toluene at 30°C. The pure (S)‐1 was obtained in 73% isolated yield with 62% conversion. Moreover, acetate (R)‐2 was converted to (S)‐1 via mesylation and followed by hydrolysis using sodium bicarbonate solution in 44% yield.     

Solvent‐Free Approach to 3,4‐Dihydropyrimidin‐2(1H)‐(thio)ones: Biginelli Reaction Catalyzed by a Wells–Dawson Reusable Heteropolyacid

The Biginelli reaction is performed in an efficient, simple, solvent‐free procedure, using a small amount of H₆P₂W₁₈O₆₂ · 24H₂O, a reusable heteropolyacid catalyst with Wells–Dawson structure. Both aromatic and aliphatic aldehydes, and different β‐dicarbonyl compounds and urea or thiourea, were used as starting materials. Seventeen examples of dihydropyrimidinones and dihydropyrimidinethiones were prepared by heating the reactants either in refluxing acetonitrile or in the absence of solvent. Operational simplicity, the use of a noncorrosive, reusable catalyst in solventless conditions, short reaction times, and very good to excellent yields in most of the selected examples are the main advantages of the method.     

Synthesis of 2‐Substituted 4,5‐Diphenyloxazoles under Solvent‐Free Microwave Irradiation Conditions

A novel method for the direct conversion of deoxybenzoin into 2‐alkyl‐4,5‐diphenyloxazoles and 2‐aryl‐4,5‐diphenyloxazoles has been developed using treatment of HTIB and nitriles under solvent‐free microwave irradiation conditions.     

Mannich‐Type Reaction Catalyzed by Silica‐Supported Fluoroboric Acid under Solvent‐Free Conditions

Three‐component Mannich‐type reaction of aldehydes, aromatic amines, and silyl enolate proceeded smoothly to afford β‐amino carbonyl compounds with good yields in the presence of a catalytic amount of HBF₄‐SiO₂.     

An Efficient Method for the Synthesis of Acylals from Aldehydes under Solvent‐Free Conditions Catalyzed by Antimony Trichloride

A mild and efficient method has been developed for the preparation of acylals from aldehydes catalyzed by antimony trichloride under solvent‐free conditions in very good to excellent yields. The easy availability, low cost, and ease of handling of the catalyst make this procedure especially attractive for large‐scale synthesis.     

Synthesis,Crystal Structure and Spectral Properties of [Ce(NO3)5(H2O)2]·2(Hphen)·(H2O)

A novel complex [Ce(NO3)5(H2O)2]·2(Hphen)·(H2O) (phen =1,10-phenanthroline) with formula C24H24CeN9O18 and Mr = 866.64 has been synthesized and structurally characterized by X-ray diffraction. It crystallizes in triclinic, space group Pī with a = 7.5534(2), b = 8.083(2), c = 25.8377(6) A, α = 86.847(1), β = 89.937(1), γ = 86.981(1)o, V = 1572.94(6) A3, Dc = 1.830 g/cm3, F(000) = 866, β = 1.545 cm-1 and Z = 2. The final refinement gave R = 0.0486 and wR = 0.1278 for 4852 observed reflections with I > 2σ(I). It consists of discrete [Ce(NO3)5(H2O)2]2- anion, two Hphen+ cations and a lattice water molecule. In the compound, all of the five nitrates are bidentate, and the coordination of Ce(III) is 12. The photo-luminescence of this compound was also investigated.