CeCl3·7H2O Catalyzed,Microwave-Assisted High-Yield Synthesis of α-Aminophosphonates and their Biological Studies

Abstract

A new class of diethyl(3,5-dibromo-4-hydroxyphenylamino) (substituted phenyl/heterocyclic) methylphosphonates 4(a–j) has been synthesized by one-pot three component simultaneous reaction (Kabachnik–Fields) of 4-amino-2,6-dibromophenol 1, substituted heterocyclic/phenyl aldehydes 2(a–j), and diethylphosphite 3 using a Lewis acid catalyst, CeCl₃·7H₂O (5 mol%) under microwave irradiation as well as conventional conditions. It was observed that microwave irradiation method is more facile, efficient, and advantageous with respect to reaction time and yields. The structures of all the synthesized compounds were supported by analyzing IR, ¹H/¹³C/³¹P NMR, and mass spectral data. The synthesized compounds were screened for their in vitro antimicrobial and antioxidant activities.     

An Efficient Synthesis of 1,5-Thiadiazepines and 1,5-Benzodiazepines by Microwave-Assisted Heterocyclization

A novel and efficient method for the synthesis of substituted thiazepines and diazepines has been developed. A simple one-pot reaction of chalcones 1a–f with 1-amino-2-mercapto-5-phenyl-1,3,4-triazole and o-phenylenediamine in the presence of a catalytic amount of sodium acetate under microwave irradiation gave 2-(3,8-diphenyl-7,8-dihydro[1,2,4]triazolo[3,4-b][1,3,4]thiadiazepin-6-yl)phenoles 2a–f and 2-(2-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)phenoles 3a–f, respectively. The structure of all the synthesized compounds was elucidated on the basis of elemental analysis, IR, ¹H and ¹³C NMR, and mass spectral data.     

Microwave‐Assisted Elimination Reaction of trans‐4‐(4‐Fluorophenyl)‐3‐chloromethyl‐1‐methylpiperidine on Alumina

Abstract

trans‐4‐(4‐Fluorophenyl)‐3‐chloromethyl‐1‐methylpiperidine 3b was subjected to elimination reaction on alumina or KF‐alumina under solvent‐free conditions and microwave irradiation. Compared with the “classical” method of heating in the presence of an organic base, the microwave‐assisted methodology provided higher yields of 4‐(4‐fluorophenyl)‐3‐methylene‐1‐methylpiperidine 7b (65.5–71%) in considerably shorter reaction times (20–40 min). Furthermore, the exocyclic double bond in 7b underwent rearrangement to the endocyclic double bond to furnish compound 8. The effect of alumina and irradiation time on reaction conversion and the extent of isomerization was examined.     

微波辐射下5-取代-2-硫代海因衍生物的合成

微波辐射下, 由硫氰酸铵与α-氨基酸通过两步反应合成了11种5-取代-2-硫代海因衍生物, 并用¹H NMR, IR和元素分析确证了中间产物和终产物的结构. 对比常规加热方法, 微波辐射具有反应时间短(4 min), 每步反应产率高(85%～93%)的优点. 同时对合成化合物2h的反应历程进行了讨论.     

A Convenient One-Pot Synthesis of Some New 3-(2-Phenyl-6-(2-thienyl)-4-pyridyl)hydroquinolin-2-ones Under Microwave Irradiation and Their Antimicrobial Activities

A series of 3-(2-phenyl-6-(2-thienyl)-4-pyridyl)hydroquinolin-2-ones 4a–o were synthesized in high yields by a one–pot cyclocondensation reaction under Kröhnke's reaction conditions using 2-chloro-3-formyl quinoline 1a–c, 2-acetyl thiophene 2, and various N-phenacylpyridinium bromides 3a–e in a mixture of ammonium acetate and acetic acid by microwave irradiation. All the compounds have been characterized by elemental analysis, FT-IR, ¹H NMR, and ¹³C NMR spectral analysis. These compounds have been screened for their antimicrobial activities.

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.     

INVESTIGATION OF THE EFFECTS OF SOME HEAT SINKS IN MICROWAVE-ASSISTED SYNTHESIS OF SOME BIGINELLI COMPOUNDS

Pyrimidine derivatives 4a–ewere synthesized by Biginelli reaction under microwave irradiation. The effectiveness of different baths or containers including ceramic, silica gel, potsherd, alumina, and molecular sieve as heat sinks in mediating the microwave irradiation for the formation of 4a–ehas been investigated. All one-pot condensations of β -Ketoester 1, aryl aldehyde 2, and (thio)urea 3in heat sinks provide high yields of the desired compounds, particularly when reactions are run at low temperature. In addition, we found that potsherd and ceramic are suitable heat sinks for preparation of these cyclocondensation products under microwave irradiation.     

微波辐射下合成5-(2-甲基/三氟甲基-苯并咪唑-1-亚甲基)-3-(苯基/p-取代苯基)-2H-1',2',4'-三唑[3,4-b]-1

分别采用微波辐射法和加热回流的常规方法, 将1-氨基-2-(2-甲基/三氟甲基-苯并咪唑-1-亚甲基)-5-巯基-1,3,4-三唑与α-溴代芳基乙酮3a～3e反应, 合成了一系列未见文献报道的1,2,4-三唑[3,4-b]-1',3',4'-噻二嗪类化合物4a～4e 和5a～5e. 微波辐射法具有反应时间短、产率高、副反应少等优点. 标题化合物经元素分析, IR, ¹H NMR, MS确证结构.     

微波辅助合成双1,2,4-三嗪化合物及其荧光特性研究

以联苯甲酰、二甲酰肼为原料, 采用微波技术合成了5个双1,2,4-三嗪化合物3, 产率72%～85%, 利用元素分析、MS, IR, ¹H NMR和荧光光谱对其结构进行了表征, 并研究了金属离子对化合物3a的荧光性质的影响. 结果表明, 微波合成具有缩短反应时间、提高产率的优点; Cu^2＋, Ni^2＋等金属离子对化合物3a产生明显的荧光猝灭作用.     

SYNTHESIS OF 4,9-DIMETHYL-8- (6-ARYL-2-THIOXO-1,2,3,6-TETRAHYDRO PYRIMIDIN-4-YL)-FURO[2,3-H]CHROMEN-2-ONES AS ANTIMICROBIAL AGENTS UNDER MICROWAVE IRRADIATION

Acrolyl furochromen-2-ones (3a–i) obtained in good yields on microwave irradiation of furochromen-2-one (1) with various simple and substituted aromatic aldehydes (2a–i). 3a–g on cyclo dehydration with thiourea in domestic microwave oven furnished tetrahydro thiaxopyrimidine furochromen-2-ones 4a–i in high yields. The structures of the newly synthesized compounds were established on the basis of analytical and spectral data, IR, and ¹H NMR.     

Effect of Microwave Irradiation on Reaction of Arylaldehyde Derivatives with Some Active Methylene Compounds in Aqueous Media

Abstract

The effect of microwave irradiation on the condensation reactions of arylaldehydes 1 and active methylene compounds 2 in aqueous media was studied and compared with “classical” conditions. The results show that the condensation was carried out only under microwave irradiation in the presence of ammonium chloride as a catalyst, followed by dehydration, to afford (E)‐olefins 3. The protocol was used to synthesize coumarins by a condensation reaction of salicylaldehyde or its derivatives with various derivatives of ethylacetate 5 (e.g., R³CH₂CO₂Et; R³: CO₂Et, CO₂Me, COMe, CN) in high yields. These investigations will contribute to the development of environmentally friendly and inexpensive processes in organic synthesis.     

Efficient Microwave‐Assisted Synthesis of 9,9‐Bis[4‐(2‐hydroxyethoxy)phenyl]fluorene from 9‐Fluorenone and 2‐Phenoxyethanol

9‐Fluorenone (1) smoothly reacts with phenoxyethanol (2) in the presence of Al³⁺‐montmorillonite catalyst and 3‐mercaptopropionic acid as a cocatalyst under microwave irradiation at 160°C for 10 min to give 9,9‐bis[4‐(2‐hydroxyethoxy)phenyl]fluorene (3) in 81% yield, which was much higher than the yield of 33% obtained by conventional heating using an oil bath. A similar acceleration effect of microwave irradiation was observed in other metal‐cation‐exchanged montmorillonite catalysts as well.     

Expeditious one-pot multicomponent microwave-assisted green synthesis of substituted 2-phenyl Quinoxaline and 7-bromo-3-(4-ethylphenyl) pyrido[2,3-b]pyrazine in water–PEG and water–ethanol

An eco-friendly, expeditious one-pot multicomponent synthesis of substituted 2-phenyl quinoxaline and 7-bromo-3-(4-ethylphenyl) pyrido[2,3-b]pyrazine 4a–k in water–ethanol from easily available starting materials as acetophenone 1, succinamide 2, aromatic amine 3, in situ-generated α-iodo acetophenone from acetophenone, succinamide and catalyzed by silver iodide in combination with green solvent polyethylene glycol-400 and water (2:1) under microwave irradiation. The newly developed protocol with excellent yield of products in very short time of reaction by avoiding the use of lacrimatic α-chloro and α-bromocarbonyl compounds, volatile, toxic organic hazardous solvents, and reagents is the advantage of this research work. The final products were confirmed by their characterization data such as FTIR, ¹H NMR, ¹³C NMR, Mass, HRMS and were compared with its reported method.     

A highly efficient,simple, and ecofriendly microwave-induced synthesis of indolyl chalcones and pyrazolines

Abstract

One-pot synthesis of indolyl chalcones (3a–c) employing indole-3-carboxaldehyde (1) and heteroaryl active methyl compounds (2a–c) under microwave irradiation is described. The indolyl chalcones (3a–c) are transformed into medicinally important pyrazolines (5a–f) using different hydrazines. Application of microwave irradiation leads to many remarkable advantages, such as solvent- and catalyst-free reaction conditions, simple work up procedure, shorter reaction time, in addition to ecofriendly ‘green chemistry’ economical and environmental impacts.     

Microwave-Assisted Synthesis of Some Pyrimidine Derivatives

Oxo-and thioxopyrimidines 4a–i were synthesized using the Biginelli three-component cyclocondensation reaction of an appropriate β-diketone, arylaldehyde, and (thio)urea under microwave irradiation. Yields of products following recrystallization from ethanol were of the order of 65–90%. ¹H and ¹³C NMR spectroscopy and elemental analysis were used for structural assignment.     

Nickel(II) complexes with mono(imino)pyrrole ligands: preparation,structure and ethylene polymerization behavior

A series of unsymmetrical mono(imine)pyrroles (L1–L3) were synthesized by microwave irradiation from 2-acetylpyrrole and a series of dimethylanilines with two methyl groups at different positions on the aniline ring. A simplified synthetic method was initiated to prepare the corresponding nickel complexes NiL₂ (1–3) with direct condensation of mono(imine)pyrrole and nickel chloride. The compounds were determined using a suite of techniques (i.e. ¹H NMR, ¹³C NMR, IR, EA, MS). L1–L3 and 3 were further characterized by X-ray crystal diffraction. The structure of 3 showed that the ligand chelated to nickel with 2?:?1 M ratio, in spite of a 1?:?1 rate of charge. Application of 1–3 in ethylene polymerization indicated that mono(imino)pyrrole nickel complexes showed low activities. The polymerization reaction time and temperature, as well as the ligand structure, influenced the catalytic performance to some extent. Experimental data showed higher activity as –CH₃ on the aniline ring is closer to the imine group.     

Three component one-pot synthesis of novel pyrimidino thiazolidin-4-ones catalyzed by activated fly ash

Abstract

2-Phenyl-3-(4,6-diarylpyrimidin-2-yl) thiazolidin-4-ones, 12–22, were synthesized with good yields in a short reaction time by the “one-pot” multicomponent reaction of the appropriate 2-amino-4,6-diarylpyrimidines, benzaldehyde, and thioglycolic acid under microwave irradiation in the presence of activated fly ash catalyst. The characterization of these compounds was confirmed by melting point, elemental analysis, MS, FT-IR, and one-dimensional NMR (¹H and ¹³C) spectroscopic data.     

Synthesis of Some Benzotriazole-Substituted Perimidines

2-substituted perimidines 3(a–g) were prepared from an acid-catalyzed reaction of 1,8-diaminonaphthalene with carboxylic acids using microwave irradiation. Addition of these perimidines to 1-chloromethyl benzotriazole in the presence of the sodium amide under reflux conditions gave benzotriazole-substituted perimidines 5(a–f). Yields of these products following recrystallization from water were of the order of 60–65%. IR and ¹HNMR spectra and elemental analysis were used for identification of these compounds.     

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.     

Zeolite as an efficient and recyclable activation surface for the synthesis of bis-thiazolidinones: theoretical screening owing to experimental biology

Abstract

Zeolite 5Å has been used as an efficient and cost effective activating catalyst for the synthesis of bis-thiazolidinones 4 (a–h) starting from bis-imines 3 (a–h) and thioacetic acid. The reactions were performed under microwave irradiation in solventless condition. The catalyst was recycled and used for several times. This reaction is scalable to multigram scale and the methodology has resulted in an efficient synthesis. A benign, environmentally friendly, efficient, and extremely fast procedure for synthesis of bis-thiazolidinones has been demonstrated. The produced bis-thiazolidinone molecules were characterized on the basis of elemental analysis, IR, mass, and ¹H-NMR spectral data. The synthesized moieties were screened virtually using some of bioinformatical softwares and discussed.     

微波作用下1-苯基-5-[5-(芳胺羰基甲硫基)-4-苯基-1,2,4-三唑-3-甲硫基]四唑的合成及生物活性

采用微波和相转移催化法通过1-苯基-5-(4-苯基-1,2,4-三唑-5-巯基-3-甲硫基)四唑(2)与2-氯乙酰芳胺(3)反应高效、快速地合成了10种尚未见文献报道的1-苯基-5-[5-(芳胺羰基甲硫基)-4-苯基-1,2,4-三唑-3-甲硫基]四唑. 其结构经 IR, ¹H NMR, ¹³C NMR 和元素分析表征. 生物活性实验结果表明, 该类化合物在较低浓度下部分化合物对小麦芽有很好的促进作用.