Simultaneous Synthesis of Pyrazolopyridines and Pyrazolopyrimidinones Under Microwave Irradiation

The direct reaction of o-aminopyrazocarbonitriles and carbonyl compounds to afford pyrazolopyrimidinones was discovered; hence, a simultaneous synthetic method for pyrazolopyridines and pyrazolopyrimidinones was achieved. Under microwave irradiation, better yields of products than those of conventional method were given.     

Microwave Assisted Condensation of Aromatic Methyl Groups with Aromatic Aldehydes

Abstract

Aromatic aldehydes are condensed with 2,4‐dinitro‐1,5‐dimethylbenzene in a Siegrist type coupling. The reported method features microwave irradiation, solvent‐free conditions, and a catalytic amount of piperidine to give a high yield of the corresponding 1,3‐bisstyryl‐4,6‐dinitrobenzenes within a few minutes.     

Synthesis of Substituted Salicylanilides under Microwave Irradiation

Summary. Salicylanilides were prepared in 70–95% yields in 4–8min from phenyl salicylate or phenyl 4-methoxysalicylate and substituted anilines under microwave irradiation under solvent free conditions.Received October 17, 2002; accepted October 22, 2002 Published online July 3, 2003     

One-Pot Synthesis of Salicylanilides by Direct Amide Bond Formation from Salicyclic Acid Under Microwave Irradiation

A highly efficient protocol for the preparation of aromatic amides is described by the direct reactions between salicyclic acid and aromatic amines in the presence of phosphorous trichloride under microwave irradiation. The method has several advantages over the conventional methods, including operational simplicity, good yield, and reduced reaction time.

Traceless Synthesis of Hydantoin by Focused Microwave Irradiation

Hydantoin analogs have shown versatile therapeutic applications and some of them have been approved by FDA as drugs. For example, Fosphenytoin as a sodium channel antagonist is used for the treatment of epilepsy. Phenytoin has antiarrhythmic, anticonvulsant and antineuralgic activities. Ethotoin and Mephenytoin both show anticonvulsant effect. Nilutamide is a non-steroidal orally-active antiandrogen in combination with surgical castration for the treatment of stage D2 metastatic prostate c…     

Solvent‐Free Synthesis of Heterocyclic Thioureas Using Microwave Technology

A new and rapid solvent‐free synthesis of heterocyclic thioureas in a microwave oven has been reported for the first time. Nine heterocyclic thioureas that possess biological activity have been synthesized. The reaction time is short (2–4.5 min) and gives excellent yields (82.9–95.5%).     

Synthesis of Glucosylguanidinohydrazones under Microwave Promotion and Ultrasound Irradiation

Guanylhydrazone derivatives were obtained by the condensation of glucosylated aminoguanidines with 3‐formylchromones in refluxing THF. Target compounds were synthesized by conventional method, microwave promotion and ultrasound irradiation methods. The structure of all new compounds was confirmed by IR, ¹H NMR, ¹³C NMR spectral data and elemental analyses.     

Microwave Irradiation Promoted Synthesis of Aryloxy Acetic Acids

Several aryloxy acetic acids were synthesized under microwave irradiation. The factors, which affect the reaction, were investigated and optimized. It was revealed that the best yields(92. 7%--97.4%) were obtained when the molar ratio of the reactants was n(ArOH) : n(NaOH) : n(CICH2CO2H) = 1：2.5： 1.2 with microwave irradiation power of 640 W for 65--85 s.     

微波辐射下苯并噁唑基吡啶的合成

在微波辐射条件下,利用邻氨基酚和吡啶羧酸在多聚磷酸中的缩合反应,合成了2种苯并唑基取代吡啶 最佳反应条件为:450W辐射4min 相比于常规反应,反应时间大为缩短且产率令人满意     

2,4,6-三芳基吡啶的微波辐射促进合成

微波辐射;查尔酮;缩合反应;吡啶;叶立德     

Rapid Syntheses of Benzyl Acetate Under Microwave Irradiation

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Synthesis of 1H‐Imidazoles Catalyzed by Cu‐Nanoparticle and Its Physicochemical Properties

Series of 1‐arylmethyl‐4, 5‐dihydro‐2‐aryl‐1H‐imidazole were synthesized expeditiously in good yields from 1,2‐diaminoethane and aromatic aldehydes in the presence of Cu nanoparticle under microwave irradiation in solvent‐free method. Monodisperse spherical Cu nanoparticles with a diameter range of 45 ± 8 nm were synthesized by polyol process. The particle size and elemental structure of copper nanoparticles were confirmed by XRD data and was found to be having a face‐centered cubic structure. The resulting substituted imidazoles have been studied in the achievement of degree of drug absorption enhancement as well as the potential associated toxicity on the basis of hypothetical antibacterial pharmacophores and structures that were designed to interact with both of gram‐positive and gram‐negative bacteria. All the synthesized molecules were characterized on the basis of 1H NMR, 13C NMR, mass spectrometry, and elemental data.     

N-烃基邻苯二甲酰亚胺的微波干法催化合成

在K2 CO3 固体碱催化下 ,利用微波辐射 ,邻苯二甲酰亚胺和卤代烃发生取代反应 ,高产率地合成了N -烃基邻苯二甲酰亚胺     

Microwave assisted one-pot tandem three-component synthesis of 2,4,5-triary 1-2-4-dihydro-3H- 1,2,4-triazol-3-one derivatives

This work described a one-pot tandem three-component synthesis of 2,4,5-triaryl-2,4-dihydro-3H- 1,2,4-triazol-3-ones using a simple reaction between phenylhydrazines, benzaldehydes and phenyl isocyanates under microwave irradiation and solvent-free conditions in good to excellent yields.     

Cycloaddition Reaction of Epoxides with Various Alkenes Under Microwave Irradiation

Abstract

The reactivity of gem-dicyano epoxides with various alkenes is studies in solvent free conditions, and in homogeneous solution, under microwave irradiation. Microwave heating of these substrates in solvent, yields carbonyl ylides which give 1-3-dipolar cycloaddition.     

Enhancement of Chemical Reactions by Microwave Irradiation

Microwaves are low electromagnetic energy which induce molecular perturbation by stimulation of ionic diffusion and by enhancement of dipole rotation without causing rearrangement of molecular structures. Microwave energy irradiated on the samples in various liquid media is lost or absorbed to the samples by the following two mechanisms: ionic conduction and dipole rotation. These two effects take place simultaneously to account for the phenomenon of rapid heating associated with many practical applications of microwave irradiation. In contrast to conventional heating, the salient feat ure of “dipole rotation” constitutes one efficient form of “molecular agitation” or “molecular stirring” which can be explored for many aspects in chemical reactions. We will discuss some of the useful application of “molecular agitation” by means of microwave irradiation such as: 1. rapid hydrolysis of proteins and peptides, 2. selective hydrolysis of aspartyl peptide bond, 3. the racemization of amino acids, 4. rapid hydrolysis of sugars, 5. continuous-flow process of microwave reactions, and 6. the enhancement of coupling reactions in peptide synthesis.     

Synthesis of 9-Substituted Berberine Derivatives with Microwave Irradiation

Hyperglycemia is frequently accompanying with hyperlipidemia. To explore the potent drugs with dual-activity and dual-site effects that could reduce blood glucose and blood lipid at the same time, fibrate group with lipid-lowering effect on the 9th position of berberine(BBR) was introduced using the drug design combination principle and the multi-target collaborative treatment method. Moreover, the molecular structure of BBR was modified, and six 9-substituted derivatives of BBR were designed and synthesized, among which, five compounds have never been reported before. In addition, the molecular structures of these derivatives were identified using liquid chromatography-mass spectrometry(LC-MS), ¹H nuclear magnetic resonance(¹H NMR) and ¹³C NMR, respectively. Furthermore, the microwave irradiation experimental technique was applied in the synthesis reaction using the novel microwave synthesizer, which accelerated the reaction rate, enhanced the reaction yield, reduced the reaction by-products, and simplified the post-processing steps. In the meantime, the 9-position regioselective demethylation of BBR was explored through quantum chemical calculation during the synthesis of berberrubine. The computations were consistent with the experimental results, which contributed to deducing the mechanism of its selective methylation.     

Solid State Desemicarbazonation on Clayfen Under Microwave Irradiation

Summary.  A new, efficient, and environmentally benign method for the cleavage of semicarbazones has been achieved by a simple reaction of semicarbazones with clayfen under microwave irradiation. Received January 4, 2001. Accepted (revised) March 1, 2001     

One-Pot Synthesis of N-Substituted 4-Aryl-1,4-dihydropyridines Under Solvent-Free Conditions and Microwave Irradiation

Summary.  The three-component condensation of benzaldehyde derivatives, alkyl propiolates, and primary amines catalyzed by silica gel, zeolite HY, montmorillonite K-10, and acidic alumina under microwave irradiation gave N-substituted 4-aryl-1,4-dihydropyridines in short reaction times and high yields. The best results were obtained with silica gel. Received March 26, 2001. Accepted (revised) June 18, 2001     

Synthesis of Azafluorenones using Zeolites.

A convenient method for the synthesis of various azafluorenones (2a-f & 4a-d) by cyclization of substituted arylpyridines (1a-f & 3a-d) using zeolites are described.