P2O5/SiO2 as an Efficient Reagent for the Preparation of Z -Aldoximes Under Solvent-Free Conditions

Abstract

A facile and efficient method for the preparation of Z-aldoximes is improved by means of P₂O₅/SiO₂ reagent in solvent-free media. Advantages of this method are the use of inexpensive and selective reagent, with high yields in simple operation, and short reaction time under solvent-free conditions.     

OH−/Silica-Mediated One-Pot Synthesis of Dithiocarbamates Under Solvent-Free Conditions

Abstract

An efficient, versatile, and environmentally benign method for the synthesis of dithiocarbamates under solvent-free conditions is reported. The Michael addition of electron-deficient alkenes with alkyl or aryl amines and CS₂ in the presence of OH^?/silica in a one-pot three-component reaction protocol gave the corresponding dithiocarbamates in good to excellent yields. This method is suitable for a wide range of amines and a variety of Michael acceptors in solvent-free conditions. The results of the present work show the desired products in excellent yields.     

Organic-salt-mediated highly regioselective N3-alkylation of 2-thiophenytoin via Michael reaction under solvent-free conditions

A regioselective N3-alkylation of 5,5-diphenyl-2-thiohydantoin (2-thiophenytoin) using a very efficient mild base K₂CO₃ and α,β-unsaturated esters in the presence of organic salt TBAB (tetrabutylammonium bromide) at room temperature has been reported (3b–3h). The selectivity of this reaction is excellent and products have been produced in good yields under solvent-free conditions. The increase of the reaction temperature to 70°C mostly disappeared this selectivity and afforded only the N1,N3-dialkylated derivatives of 2-thiophenytoin in good yields (4b–4g). We were unable to selectively N3-alkylate 2-thiophenytoin with ethyl acrylate at both room temperature and 70°C under the same conditions (4a). Dimethyl and diethyl fumarates cannot work as Michael acceptors and were hydrolyzed to fumaric acid under reaction conditions.     

TETRABUTYLAMMONIUM PEROXYDISULFATE IN ORGANIC SYNTHESIS. XII.[1] A CONVENIENT AND PRACTICAL PROCEDURE FOR THE SELECTIVE OXIDATION OF THIOLS TO DISULFIDES WITH TETRABUTYLAMMONIUM PEROXYDISULFATE UNDER SOLVENT-FREE CONDITIONS

ABSTRACT

An efficient method for the oxidative coupling of thiols to their corresponding disulfide by (n-Bu₄N₂)S₂O₈ in high yields under solvent-free conditions is described. The reaction was applicable to a variety of thiols with high chemoselectivity.     

Conventional and Microwave-Assisted Facile One-Pot Synthesis of N-Substituted Pyrrole-2,3,4,5-tetracarboxylates Under Neat Conditions

Highly substituted pyrroles 3a,f were prepared conveniently in a reaction of (dimethyl- and diethyl-)acethylenedicarboxylates 1a–b with N-(methyl- and aryl-) hydroxylamines 2a–d in the presence of NaHCO₃ using both conventional heating and microwave irradiation. Excelent yields of the very pure products were isolated under solvent-free conditions both at classical as well as microwave heating.     

Solvent-free reductive amination of aromatic aldehydes catalyzed by CeCl3·7H2O

Abstract

CeCl₃·7H₂O is found to be an efficient catalyst in the one-pot reductive amination of aromatic aldehydes under solvent-free conditions. Selectivity is observed in the reaction of cinnamaldehyde with aromatic amines, providing an alternative green route to the synthesis of N-cinnamyl anilines. The reaction conditions are mild and the desired product is obtained in good yields.     

[Bmim]Br3对酮的选择性单溴化反应

在无溶剂和室温条件下, 三溴化1-丁基-3-甲基咪唑([Bmim]Br₃)选择性地与酮反应, 以90%～96%的产率生成相应的α-溴代酮. 该方法反应条件温和、产率高、选择性好、环境友好.     

The Synthesis and Bioactivity of Dimethyl (2,3- Dihydrobenzo[b][1,4]Dioxin-6-Yl)(Aryl Amino)Methylphosphonates

Abstract

A new series of α-aminophosphonates have been synthesized by a one-pot three-component reaction of 2,3-dihydrobenzo[b][1,4]dioxine-6-carbaldehyde, various amines, and dimethyl phosphite by using nano-TiO₂ as a catalyst under solvent-free conditions at 50°C. The major advantages of the present method are high yields, short reaction times, recyclable catalyst, and solvent-free reaction conditions. Among these new structurally diversified set of α-aminophosphonates, dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(3-nitrophenylamino) methylphosphonate and dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(4-fluoro-3-nitro-phenyl-amino) methylphosphonate have shown higher antioxidant activity in diphenyl picryl hydrazyl (DPPH) scavenging, reducing power assay, and lipid peroxidation methods.     

NH4H2PO4/SiO2: a recyclable,efficient heterogeneous catalyst for crossed aldol condensation reaction

Abstract

Crossed aldol condensation of aromatic aldehydes with cyclic ketones in the presence of catalytic amount of NH₄H₂PO₄/SiO₂ (as a safe, green, and cheap heterogeneous catalyst) under solvent-free condition afforded α,?-bis(substituted-benzylidene) cycloalkanones in high yields. This method is general with respect to all types of aromatic aldehydes and is an eco-friendly procedure. And the catalyst is easily prepared, stable, reusable, and efficient under the reaction conditions.     

无溶剂条件下合成2-[3-氧代-1,3-二(未)取代苯基丙基]-1,2,3,4-四氢萘-1-酮

以3,4-二氢-1-萘酮和查尔酮为原料, 在 K₂CO₃-NaOH 存在下, 无溶剂室温研磨反应, 方便地得到2-[3-氧代-1,3-二(未)取代苯基丙基]-1,2,3,4-四氢萘-1-酮. 该方法具有反应条件温和、操作简单和产率较高等优点, 并通过IR, ¹H NMR, 元素分析确定了产物的结构, 3b晶体结构通过X衍射测定.     

无溶剂中性条件下分子I2或Fe(NO3)3·9H2O/NaI原位生成的I2催化醇与甲酸甲酰化反应

 Different alcohols were formylated by formic acid under solvent-free conditions in the presence of iodine as the catalyst with good-to-high yields at room temperature. I₂ generated in situ from Fe(NO₃)₃·9H₂O/NaI also catalyzed the formylation of the alcohols under solvent-free conditions. This gives a green and efficient reaction at room temperature, in which the use of toxic and corrosive molecular I₂ is avoided.     

A rapid, solvent-free, ligandless and mild method for preparing aromatic ketones from acyl chlorides and arylboronic acids via a Suzuki-Miyaura type of coupling reaction

Aromatic ketones were synthesized via a palladium catalyzed cross-coupling reaction of boronic acids with acyl chlorides in the presence of Na₂CO₃ at room temperature under solvent-free conditions. The ligand-free and mild reaction conditions, highly rapid reaction rate and good to excellent yields are important features of this method.     

A Green and Efficient Approach for the Synthesis of 3-Chalcogen Benzo[b]Furans via I2-Mediated Cascade Annulation Reaction of 2-Alkynylanisoles at Room Temperature in Water

Abstract

An efficient and green aqueous protocol to access 3-chalcogen benzo[b]furan derivatives has been developed. The reaction can proceed via I₂-mediated intramolecular annulation reaction of 2-alkynylanisoles with diaryl disulfides (diselenides) in water or under solvent-free conditions at room temperature. With the participation of I₂, a variety of 3-chalcogen benzo[b]furan derivatives were obtained in good to excellent yields. This reaction was considered to work via an iodocyclization cascade mechanism and the intermediate 3-iodo-2-phenylbenzofuran was detected by GC-MS.     

Stannous Chloride–Promoted Synthesis of S-Allyl-N-aryl Dithiocarbamates under Solvent-Free Conditions

Abstract

A highly efficient method of synthesis of S-allyl-N-aryl dithiocarbamates using SnCl₂ as a catalyst under solvent-free conditions is described. The mild reaction conditions, high yields, and shorter reaction period illustrate the good synthetic utility of this method.     

H6P2W18O62·14H2O as an efficient catalyst for the green synthesis of α-aminophosphonates from α-amino acids

Abstract

A simple, efficient and eco-friendly protocol has been described for the synthesis of α-aminophosphonates via Kabachnik-Fields reaction, catalyzed by H₆P₂W₁₈O₆₂·14H₂O as a reusable catalyst. The reaction was realized by condensation of amino acids, various aromatic aldehydes and triethylphosphite under solvent-free conditions, the corresponding α-aminophosphonates were formed in good yields. All the new products were characterized by IR, ¹H, ¹³C and ³¹P-NMR analyses. This method offers advantages such as simplicity workup with the green aspects, good yields and short reaction times.     

Facile synthesis of 3-substituted indoles containing highly polarized double bonds

In this paper, an effective procedure is described for the synthesis of novel indoles containing highly polarized double bonds. The strategy involves the preparation of (indolylmethyl)malononitriles via the one-pot three-component reaction of an aldehyde, malononitrile and indole in the presence of Zn(OAc)₂/NaOAc under silent and ultrasonic conditions. The reaction further proceeds through oxidative elimination under solvent-free conditions in the presence of Ca(OCl)₂ to furnish indolylacrylonitriles in high yields and short reaction times.     

First sonochemical,simple and solvent-free synthesis of chiral tert-butanesulfinimines using silica supported p-toluenesulfonic acid

A solvent-free, versatile procedure has been developed for the effective synthesis of tert-butanesulfinylimines of a variety of aldehydes using chiral tert-butanesulfinamides under green, sonochemical conditions. This method utilizes silica supported p-toluenesulfonic acid (pTSA·SiO₂) as an efficient, safer and inexpensive catalyst under aerobic conditions. The practicable simplicity, easy preparation of the catalyst from readily available substances, high substrate scope, excellent yields of products in short reaction times and environmentally benign (solvent-free sonochemical) conditions are the exceptional assets of this finding.     

Synthesis of 1-Substituted 4(1H)-Quinazolinones Under Solvent-Free Conditions

Abstract

Heating a mixture of 2-(N-alkylamino)benzoic acids, triethyl orthoformate, and ammonium acetate under solvent-free conditions generated 1-substituted 4(1H)-quinazolinones in 73?99% yields. Moreover, a possible reaction pathway was proposed.     

An efficient hydrocyanation of α, β-unsaturated diesters with TMSCN catalyzed by MgI2 etherate

Abstract

A mild, efficient and highly regioselective addition of trimethylsilyl cyanide (TMSCN) to α,β-unsaturated diesters has been achieved by using MgI₂ etherate as catalyst under solvent-free conditions. This protocol provides the corresponding β-cyano esters in high yields.     

KF/Al2O3 as an Efficient,Green, and Reusable Catalytic System for the Solvent-Free Synthesis of N-Alkyl Derivatives of Sulfonamides via Michael Reactions

KF/Al ₂ O ₃ efficiently catalyzes the microwave-assisted Michael addition of sulfonamides to α,β-unsaturated esters under solvent-free conditions to afford N-alkyl derivatives of sulfonamides as biologically interesting compounds in high yields and in short reaction times. In this reaction, N,N-dialkylsulfonamides are also produced, but in very low yields.