Facile Synthesis of Triarylpyrimidines with Microwave‐Irradiated Reactions of N‐Phenacylpyridinium Chloride

In a system of ammonium acetate and acetic acid under microwave irradiation, N‐phenacylpyridinium chloride 1 reacted with 2 mol of aromatic aldehydes 2a–h to give 2,4,6‐triarylpyrimidine 3a–h, reacted with pyridinecarboxaldehyde 4a–c and acetophenone 5 to yield bipyridine derivatives 6a–c. The structure of the products was characterized with ¹H NMR, ¹³C NMR, IR, and mass spectroscopy.     

Solvent-Free Crossed Aldol Condensation of Cyclic Ketones with Aromatic Aldehydes Assisted by Microwave Irradiation

Summary. A fast alumina-promoted crossed aldol-condensation reaction of aldehydes and cyclic ketones under microwave irradiation is described. This process is simple, efficient, and environmentally benign and proceeds in fairly high yield without any self-condensation.     

Reactions of β-Pinene with Aromatic Aldehydes

Aromatic aldehydes add to β-pinene under Lewis acid catalyzed Prins reaction conditions and yield the corresponding homoallylic alcohols. The reactions proceed in poor yield when electron donating substituents are present on the aromatic ring.     

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.     

微波促进的5-氯-3-甲基-1-苯基-4-吡唑甲醛与氯化N-苯乙酮基吡啶及芳酰肼的缩合反应

5-氯-3-甲基-1-苯基-4-吡唑甲醛(1)在微波辐射下, 与氯化N-苯乙酮基吡啶(2)和取代苯乙酮3在醋酸铵/醋酸体系中一锅煮反应, 高产率地生成了吡唑基取代的吡啶衍生物4a～4e. 1与芳酰肼在微波辐射下反应, 则形成了酰腙类化合物6a～6g. 1与羟胺在微波辐射下缩合可生成肟7a和腈7b的混合物.     

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     

超声辐射下水相介质中金属锡引发芳香醛酮的烯丙基化反应

超声波作用下, Sn/H₂O体系中, 芳香醛酮在室温下进行烯丙基化反应, 45 min内得到60%～98%的烯丙基化产物.     

Efficient Synthesis of Dicycloalkenopyridines： One-pot Multicomponent Condensation of Aldehydes with Cyclic Ketones

Under microwave irradiation, the one-pot multicomponent condensation reaction of three moles of aromatic aldehydes with two moles of cyclic ketones having free α,α'-methylene positions such as cyclopentanone or cyclohexanone in the presence of ammonium acetate and acetic acid afforded dicycloalkenopyridines with two α-arylidene groups in high yields. Under the similar reaction condition, the reaction of aromatic aldehydes with 1-tetralone having only one α-methylene position alternatively resulted in 10-ary...     

Microwave Assisted Oxidation of Aromatic Aldehydes

Aromatic aldehydes are converted to carboxylic acids in 6-8 minutes, and in the absence of any external promoting agent, under microwave irradiation conditions.     

芳香醛与丙二酸亚异丙酯的固相缩合反应

二甲基芳亚甲基二氧六环二酮;芳香醛与丙二酸亚异丙酯的固相缩合反应     

微波辐射金属铝诱发芳香醛的还原偶联反应

一系列芳香醛在Al-TiCl3-CH2Cl2体系中反应12h,以20％～70％的产率得1,2-二醇产品,相同体系中微波辐射8rain相应1,2-二醇的产率达65％～94％.微波辐射下合成1,2-二醇的优点是时间短、产率高、操作简单.     

Comparison of Conventional and Microwave Assisted Reactions Giving Aromatic Oxazolidines

Summary. By reaction of aromatic aldehydes with (-)-ephedrine aromatic 1,3-oxazolidines can be obtained. The reaction was carried out either at conventional conditions or by microwave heating. The different diastereomeric ratios were determined by means of ¹H NMR spectroscopy.Received December 19, 2002; accepted December 23, 2002 Published online June 2, 2003     

Studies on the Neodymium-induced Pinacol Coupling of Aromatic Aldehydes and Ketones in Aqueous Media

1,2-Diols are very useful synthons for a variety of organic synthesis1, which have been used as intermediates for the construction of the skeletons of the biologically important natural products2. Within the last several years, various metals, such as Mg3…     

Study of SNAr Reactions of Halobenzenes with Imidazole under Ultrasonic and Microwave Irradiation

Summary. Nucleophilic aromatic substitution reactions with imidazole of haloarenes having strongly electron-withdrawing groups were studied under ultrasonic and microwave irradiations. The course of the S_NAr reactions was found to be strongly dependent on the electron-withdrawing properties of the substituents as well as on the leaving ability of the halogen atom. Microwave irradiation allowed to shorten the reaction time and to increase the yields compared with ultrasonic irradiation.     

Studies on the Allylation Reactions of Aldehydes and Ketones with Lanthanum in Water

The allylation reactions of aldehydes and ketones were carried out in 25%–98% (or 29%–96%) yield with La/SnCl₂/H₂O under ultrasound irradiation (or stirring) at rt for 1 h (or 4 h). The main advantage of the present procedure is the higher yield and the environmentally benign method.     

Allylation Reactions of Aromatic Aldehydes with Antimony in Aqueous Media Under Ultrasonic Irradiation

The allylation reactions of aromatic aldehydes with allyl bromide were carried out in 89–98% yield with Sb-H₂O-KF-CH₃OH under ultrasound irradiation at rt for 2.5 h. The reactions in the same system gave allylic alcohols in 30–69% yield with stirring for 24 h. The main advantages of the present procedure are shorter reaction time, better yield, and environmental friendliness.     

微波干法催化醛酮与胺的缩合反应

利用微波辐射和固体中性Al2 O3 载体催化醛酮与胺的缩合反应的方法合成了十六种亚胺 ,研究了微波功率、作用时间、产物提取方式等因素对反应的影响 ;与无微波作用的一般合成方法相比 ,该法明显地提高反应速度及产率 ;文中用低极性熔点递变物质灌装毛细管的方法观测微波作用下反应温度 ,探讨微波作用化学反应的机理 ,其机理除与微波加热作用有关外还与分子间氢键及分子的缔合性有关。     

超声波辐射下金属锰引发芳香醛的偶联反应

超声波引发下Mn-H2O-HOAc体系中进行的一系列芳香醛的偶联反应,室温反应3 h得到45%～71%的邻二醇产品.     

Clean Synthesis in Water：Darzens Condensation Reaction of Aromatic Aldehydes with Phenacyl Chloride

The Darzens condensation reaction of aromatic aldehydes with phenacyl chloride proceeded very efficiently in a water suspension medium in the presence of triethylbenzylammonium chloride and only trans-2,3-epoxy-1,3-diaryl-1-propanones were formed which can be isolated simply by filtration.The structures of these compounds were confirmed by elemental analysis,IR and ^1H NMR spectra.Therir configurations are in agreement with that of the same compounds reported in the literature.Compared to the classical Darzens condensation,this new method has the advantages of good yields,high stereoselectivity,low running cost inexpensive and environmentally benign procedure.     

芳香醛与硫代巴比妥酸的缩合反应研究

通过微波辐射、用水作溶剂及在醋酸铵催化下的固相研磨等，研究了芳香醛与 硫代巴比妥酸的缩合反应。在三种反应条件下都得到了5-芳亚苄基硫代巴比妥酸， 并通过IR，~1H NMR和元素分析确定了产物的结构。