Thiocyanation of Aromatic and Heteroaromatic Compounds using Ammonium Thiocyanate and I2O5

Thiocyanation of indoles, pyrrols, and anilines has been efficiently achieved using ammonium thiocyanate as a thiocyanation agent and I₂O₅ as an oxidant.     

NbCl5 as an Efficient Catalyst for Chemoselective Synthesis of 1,1-Diacetates Under Solvent-Free Conditions

A mild and efficient method for the chemoselective preparation of 1,1-diacetates catalyzed by NbCl₅(5 mmol%) under solvent-free conditions has been developed. The yields are in the range of 93–98%. This protocol offered several advantages, including low catalyst loading, good yields, short reaction times, and environmentally friendliness.     

AlCl3/PCC-SiO2-Promoted Oxidation of Azaindoles and Indoles

Abstract

A simple and efficient method is described for the oxidation of 7-azaindoles and indoles to 7-azaisatins and isatins using pyridinium chlorochromate–silica gel (PCC-SiO₂) with the aid of Lewis acid catalyst aluminium chloride (AlCl₃) in dichloroethane. Simplicity of the reaction conditions, easy workup procedure, and good yields are the key features of this protocol.     

Highly Regioselective Ring Opening of Epoxides with Thiols Catalyzed by SbCl3 Under Solvent-Free Conditions

The ring-opening reaction of epoxides with thiols by SbCl ₃ supported on Kieselguhr under solvent-free conditions, afforded high yields of β-hydroxy sulfides. Nucleophilic attack of the thiols occurs regioselectively at the less hindered side of the epoxides.     

Solvent-Free C-Benzoylation and N-Benzoylation Reactions Using Microwave Heating

An ecofriendly and efficient microwave-irradiated solvent-free benzoylation method was developed. The procedure for C-benzoylation used 50 mol% AlCl₃ as a Lewis acid catalyst at 130 °C and was completed in 10 min. The isolated yield was between 71% and 100%. N-benzoylation was conducted in a catalyst-free environment at 130 °C in 10 min. The isolated yield was between 80% and 100%.

Chemoselective Deprotection of Thioacetals/Thioketals Using HIO3 in the Presence of Wet SiO2 Under Mild Solvent-Free Conditions

Abstract

HIO ₃ in the presence of wet SiO ₂ is highly efficient and a mild reagent for selective deprotection of a variety of thioacetals/thioketals to the corresponding parent carbonyl compounds at room temperature and under solvent-free conditions.     

Fe(HSO4)3 Promoted Trimethylsilylation of Alcohols and Phenols in Solution and Under Solvent-Free Conditions

Summary. Alcohols and phenols are efficiently converted to their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of Fe(HSO₄)₃ in solution and under solvent-free conditions.     

Simple and Highly Efficient Catalytic Thiocyanation of Aromatic Compounds in Aqueous Media

Two simple, mild, and efficient procedures for the thiocyanation of N‐heterocycles, substituted anilines (electron‐rich and electron‐deficient), and N‐substituted aromatic amines at room temperature are reported (Table 3). The first uses H₂O₂ as pollution‐free oxidant and the second H₅IO₆; both with the reagent potassium thiocyanate in H₂O as solvent. These procedures provided the target thiocyanates after a short reaction time in good to excellent yields and high regioselectivity.     

Highly Efficient Synthesis of Substituted Benzenes in the Presence of B(HSO4)3 as a New and Reusable Catalyst Under Solvent-Free Conditions

A highly efficient and simple procedure for the synthesis of substituted benzenes is described. A broad range of ketones (alkyl–aryl ketones and cyclic ketones) were condensed via a cyclotrimerization reaction in the presence of catalytic amounts of boron sulfonic acid [B(HSO₄)₃], a new, highly efficient, and reusable catalyst, under solvent-free conditions. All reactions completed in short times without formation of any by-products. The catalyst was recovered and reused successfully for 15 cycles of the reaction.

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

Simple and Efficient Method for Acetylation of Alcohols,Phenols, Amines,and Thiols Using Anhydrous NiCl2 Under Solvent-Free Conditions

Solvent-free acetylation of alcohols, phenols, amines, and thiols with acetic anhydride (Ac₂O) in the presence of 0.1 mol% (13 mg) anhydrous NiCl₂, an inexpensive and easily available catalyst. Excellent yields, short reaction time, and mild reaction conditions are important features of this method.     

Simple and Efficient Method for Acetylation of Alcohols,Phenols, Amines,and Thiols Using Anhydrous NiCl2 Under Solvent-Free Conditions

Solvent-free acetylation of alcohols, phenols, amines, and thiols with acetic anhydride (Ac₂O) in the presence of 0.1 mol% (13 mg) anhydrous NiCl₂, an inexpensive and easily available catalyst, is described. Excellent yields, short reaction time, and mild reaction conditions are important features of this method.     

Synthesis of N-Substituted Pyrroles Under Catalyst- and Solvent-Free Conditions

N-Substituted pyrroles were synthesized under neat conditions by the reaction of aromatic amines with 2, 5-dimethoxytetrahydrofuran in excellent yields.     

Simple Synthesis of Pyrroles Under Solvent-Free Conditions

Paal–Knorr condensation of 2,5-hexadione with primary amines in the presence of a catalytic amount of praseodymium(III) trifluoromethanesulfonate under solvent-free conditions has been accomplished with an excellent yield. This method is a very easy, rapid, and high-yielding reaction for the synthesis of N-substituted pyrrole derivatives.     

Solvent-Free Conditions as an Eco-Friendly Strategy for Synthesis of Organophosphorus Compounds

A series of diverse NH- and CH-acids are used for a one-pot synthesis of stable phosphorus ylides and 1,4-diionic organophosphorus compounds by trapping of the zwitterionic intermediate from the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates under solvent-free conditions. The structural geometry for one of the products was confirmed by single crystal X-ray diffraction analysis.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

AlCl3 as an Efficient Catalyst Toward the Synthesis of 1,6-Dihydropyrazine-2,3-dicarbonitrile Derivatives

Aluminium chloride has been shown to be an efficient catalyst for the multicomponent reactions of diaminomaleonitrile (DAMN), ketones or aldehydes, and isocyanides for the synthesis of 1,6-dihydropyrazine-2,3-dicarbonitrile derivatives using comparative study with various catalysts. Unprecedented use of aromatic and aliphatic aldehydes in this multicomponent reaction (MCR) was demonstrated.

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

Nano-TiO2: An Efficient and Reusable Heterogeneous Catalyst for Ring Opening of Epoxides Under Solvent-Free Conditions

Nano-TiO₂ is an effective heterogeneous catalyst for the ring opening of epoxides with aromatic amines to afford β-amino alcohols in good to excellent yields at room temperature under solvent-free conditions. It was found that the catalyst is recyclable, and the activity of the catalyst was not weakened markedly even after several reaction cycles. In addition, the catalytic activity of TiO₂ strongly depends on particle size or surface area.     

AlCl3-Catalyzed transformations of organo(trichloromethyl) silanes

Reactions of organo(trichloromcthyl)silanes RMc₂SiCCl₃ (R = Me, Ph, Mc₃Si) with aluminum chloride have been studied. The interaction of trimetltyl(tricltlorometltyl)silane with AlCl₃ carried out in cyclohexane or in benzene leads to Me₃SiCHCI₂ (in 75 % yield) or ClMe₂SiCPh₂Me (in 70 % yield), respectively; whereas no conversions are observed inn-hexane and methylene chloride. Treatment of dimetltyl(phenyl)(ricltloromethyl)silane with aluminum chloride in a_n-C₅H₁₂/CH₂CI₂ mixture gives an aromatic cross-linked insoluble polymer. The reaction of pentamethyl(trichloromcthyl)disilane (R = Mc₃Si) with AICl₃ in pentane affords the rearrangement product, Me₃SiCCl₂SiMc₂Cl, in 65 % yield. In methylene chloride the further cleavage of the disilane occurs to yield Me₂SiCl₂ and CH₂=CHMe₂SiCl.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1511-1515, June, 1996.     

One-Pot Synthesis of Phenacyl Esters from Acetophenone, [Bmim]Br3, and Potassium Salts of Carboxylic Acids Under Solvent-Free Conditions

One-pot synthesis of phenacyl esters from acetophenone, [Bmim]Br₃, and potassium salts of carboxylic acids under solvent-free conditions gave the corresponding phenacyl esters with excellent yields.     

Theoretical characterization and many-body expansion analysis of BF3, BCl3, AlF3 and AlCl3 interactions

Summary Metalloid-nonmetal and Metal-nonmetal interactions of BF₃, BCl₃, AlF₃ and AlCl₃ were examined at the matrix Hartree Fock level ofab initio theory. Structural and energetic properties, many-body expansion convergence, short- and long-range components of interaction energies, and group-theoretical parameters were found to uniquely characterize these interactions.