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.     

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.     

MMPP (Magnesium Monoperoxyphthalate) in Acetonitrile; A New Approach to the Synthesis of Lactones via Baeyer-Villiger Oxidation of Cyclic Ketones

A variety of unsubstituted and mono- or di-substituted cycloalkanones can be oxidised with modest excess of magnesium monoperoxyphthalate hexahydrate in acetonitrile to produce the corresponding lactones in a facile, selective, and high yielding manner.     

Chemoselective Reduction and Transesterification of α-Keto Propargylic Esters Mediated by NaBH4 and CeCl3 · 7H2O

An efficient one-pot synthesis of α -hydroxy propargylic esters by chemoselective reduction followed by transesterification using NaBH₄ in combination with CeCl₃ · 7H₂O is described.

RuCl3-DCHA Catalyst System: A Selective Aerobic Oxidation of Primary Benzylic Alcohols Under Mild Conditions

The aerobic oxidation of benzylic alcohols to their corresponding aldehydes was performed in a RuCl₃ · 3H₂O–dicyclohexylamine (DCHA) catalyst system under ambient atmosphere at room temperature. It is noteworthy that the RuCl₃ · 3H₂O–DCHA system displayed a preference for the primary versus secondary benzylic alcohols in both intermolecular and intramolecular competition experiments.     

NaBrO3/NaHSO4 · H2O as a Versatile Reagent System for the Oxidation of Benzylic Alcohols and Aldehydes

The oxidation of benzylic alcohols and aldehydes by NaBrO₃ is efficiently promoted in the presence of NaHSO₄ · H₂O. All reactions were performed under mild and completely heterogeneous conditions in good to high yields.     

Highly Efficient and Selective Deprotection Method for Prenyl,Geranyl, and Phytyl Ethers and Esters Using Borontrifluoride–Etherate

An efficient, simple, and practical method has been developed for the deprotection of prenyl, geranyl, and phytyl ethers and esters of aromatic and aliphatic compounds using borontrifluoride–etherate (BF₃ · OEt₂) at room temperature in good to excellent yields for the first time.

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

Silica‐Supported Sodium Hydrogen Sulfate Catalyzed Facile Transformation of p‐Hydroxybenzyl Alcohols to p‐Hydroxybenzyl Ethers and Thioethers

Abstract

The heterogeneous catalyst, silica‐supported sodium hydrogen sulfate (NaHSO₄ · SiO₂) has been found to be highly efficient in carrying out the transformation of p‐hydroxybenzyl alcohols at room temperature to p‐hydroxybenzyl ethers and thioethers in very high yields.     

Solvent‐Free Chemoselective Synthesis of 1,1‐Diacetates Catalyzed by Cu(NO3)2 · 3H2O

1,1‐Diacetates have been synthesized by the reaction of a variety of aldehydes with acetic anhydride in the presence of cupric nitrate as catalyst under solvent‐free conditions. Ketones were not converted to the corresponding diacetates under these conditions.     

Glycerin and CeCl3 · 7H2O: A New and Efficient Recyclable Reaction Medium for the Synthesis of Quinoxalines

An efficient and environmentally benign process for the synthesis of quinoxalines has been developed using glycerine–cerium chloride as a reaction medium. This method is applicable to a variety of diketones and 1,2-phenylenediamines to afford the corresponding quinoxaline derivatives in excellent yields. The reaction medium was recovered and reused for further reactions without any problem.     

Supramolecular inclusion of a pillared double-layered host by an anion-directed second-sphere coordination

In this paper, we have illustrated the utilisation of a second-sphere coordination approach to construct supramolecular inclusion solids with varieties of guest molecules. A flexible molecule N,N,N′,N′-tetra-p-methylbenzyl-ethylenediamine (L1) bearing doubly protonated H-bond donors was designed, capable of forming N–H…Cl hydrogen bonds with a crystallographically unique chloride anion, to construct an anion-directed ligand. The pillared double-layered host framework was constructed by an anion-directed ligand and primary coordination sphere [CoCl₄]^2 ?  through weak C–H…Cl hydrogen-bonding interactions. A variety of guest molecules, such as p-anisaldehyde, 1,4-dimethoxy-2,5-bis(methoxymethyl)benzene, can be included, leading to the formation of novel supramolecular inclusion solids: [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₈H₈O₂]·0.25[CH₃OH] (1) and [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₁₂H₂₀O₄]·0.5[CH₃OH] (2).

We have presented herein the utilisation of a second-sphere coordination approach to construct supramolecular inclusion solids with a variety of guest molecules. A novel type of a pillared double-layered host framework was constructed by a second-sphere coordination between the anion-directed ligand (L1 = N,N,N′,N′-tetra-p-methylbenzyl-ethylenediamine) and [CoCl₄]^2 ?  through weak C–H…Cl hydrogen-bonding interaction, and a variety of guest molecules, such as p-anisaldehyde, 1,4-dimethoxy-2,5-bis(methoxymethyl)benzene, can be included, leading to the formation of supramolecular inclusion solids: [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₈H₈O₂]·0.25[CH₃OH] (1) and [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₁₂H₂₀O₄]·0.5[CH₃OH] (2)

     

CuSO4 · 5H2O: A Novel,Green, Reusable,and Environmentally Friendly Catalyst for the One-Pot,Four-Component Synthesis of β-Acetamido Carbonyl Compounds

Multicomponent reactions for the synthesis of β-acetamido carbonyl compounds have been gained considerable attention in organic synthesis. In this articles, aromatic aldehydes have been employed in a one-pot reaction with enolizable ketones, acetonitrile, benzonitrile, and acetyl chloride in the presence of copper(II) sulfate petahydrate at ambient temperature to afford the corresponding β-acetamido ketones in very good yields. New compounds are reported. The use of readily available copper(II) sulfate petahydrate as a reusable and recyclable catalyst makes this process quite simple, convenient, and environmentally friendly.     

FeCl3 · 6H2O-Catalyzed Acceleration of the Acylation of Sodium Azide with N-Acylbenzotriazoles

Catalyzed by ferric chloride hexahydrate (FeCl₃ · 6H₂O), the acylation of sodium azide with N-acylbenzotriazoles was greatly accelerated in a mixed solvent of acetone and water. Thus, good to excellent yields of a variety of acyl azides were obtained at room temperature in a short time. Furthermore, because of the complete conversion of N-acylbenzotriazoles and the easy removal of the by-product, purification by column chromatography was no longer required, which made the protocol suitable for large-scale preparation.

ZrOCl2•8H2O-Catalyzed One-Pot Multicomponent Synthesis of β′-Acetamido-β-dicarbonyl Compounds with Special Reference to pref-Selective β′-Acetamido-β-ketoesters

ZrOCl₂ · 8H₂O catalyzes the one-pot synthesis of β′-acetamido-β-dicarbonyl compounds in high yields from aldehyde, enolizable β-dicarbonyl compound, acetyl chloride, and acetonitrile in solvent as well as in solvent-free conditions. β′-Acetamido-β-ketoesters are formed in moderate to exclusive pref-diastereoselectivity.     

Cu(ClO4)2 · 6H2O as an Efficient Catalyst for the Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Under Solvent-Free Conditions

Cu(ClO₄) · 6H₂O efficiently catalyzes the three-component Biginelli reaction of aldehyde, β-dicarbonyl compounds, and urea or thiourea under solvent-free conditions to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones in excellent yields.      

Modified One‐Pot Protocol for the Preparation of Thioglycosides from Unprotected Aldoses via S‐Glycosyl Isothiouronium Salts*

An efficient one‐pot protocol for the direct preparation of thioglycosides starting from unprotected reducing sugars via S‐glycosyl isothiouronium salts is reported. In this one‐pot methodology, BF₃ · OEt₂ has been used as a general catalyst for both per‐O‐acetylation of sugars and conversion of sugar per‐O‐acetates into S‐glycosyl isothiouronium salts, which was allowed to react with alkylating agents in the presence of a base to furnish thioglycosides in excellent yield.     

Ferrous Sulfide/Aqueous Ammonia: Simple,Efficient, and Chemoselective Reagent for the Conversion of Aromatic Azide to Amine

A practical, environmentally benign, rapid, and efficient method for the reduction of aromatic azide to amine is described using FeS/aqueous ammonia in the presence of other reducible functionalities. Application of a novel reducing reagent results in aromatic amines with excellent yield and high chemoselectivity, without need of any purification techniques.     

Aromatization of Hantzsch 1,4-Dihydropyridines with Al(NO3)3·9H2O and/or Fe(NO3)3·9H2O in the Presence of Silica Sulfuric Acid Under Mild and Heterogeneous Conditions

A simple and convenient method for the aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridines is achieved via combination of aluminum or ferric nitrates and silica sulfuric acid as environmentally friendly and novel oxidizing media. This oxidation was carried out in dichloromethane under heterogeneous conditions with good to excellent yields.