1,3-Dibromo-5,5-dimethylhydantoin as a useful reagent for efficient synthesis of 3,4-dihydropyrimidin-2-(1<Emphasis Type="Italic">H</Emphasis>)-ones under solvent-free conditions

Efficient syntheses of 3,4-dihydropyrimidin-2-(1H)-ones and the corresponding thioxo derivatives using 1,3-dibromo-5,5-dimethylhydantoin (DBH) catalysis of a one-pot three-component Biginelli reaction of aldehydes, ethyl acetoacetate, and urea or thiourea under microwave irradiation are described. The advantages of this method are its short reaction times, high yields of the products, inexpensive and commercially available catalyst, and solvent-free conditions. Typical isolated yields exceed 70 % for arylaldehydes (9 examples) and aliphatic aldehydes (2 examples).     

InCl3-catalyzed three-component reaction: a novel synthesis of dihydropyrano[3,2-b]chromenediones under solvent-free conditions

Three-component coupling (3CC) of kojic acid, aldehyde and 1,3-dione has been achieved in the presence of 10 mol % InCl₃ under solvent-free conditions to afford the corresponding dihydropyrano[3,2-b]chromenedione derivatives in good yields. This is the first example of the condensation of kojic acid, aldehyde and 1,3-diones to provide a novel series of kojic acid derivatives.     

Condensation Reactions of Sulfur-Containing Chalcone Analogs

Three-component condensation of heterocyclic chalcone analogs containing a thiophene ring with 5,5-dimethylcyclohexane-1,3-dione (dimedone) and ammonia at 140–145°C under pressure afforded functionalized 1,4,5,6,7,8-hexahydroquinoline derivatives; the corresponding triketones were formed under milder conditions (100–105°C). The condensation of 1,3-di(thiophen-2-yl)prop-2-en-1-one with dimedone and ammonia under harsh conditions unexpectedly produced functional 1,2,3,4,5,6,7,8,9,10-decahydroacridine derivative. Heterocyclic chalcone analogs reacted with ethyl acetoacetate in the presence of ammonia to give cyclocondensation products, ethyl 2-oxocyclohex-3-ene-1-carboxylates.     

氯代膦烯化合物与零价钯的氧化加成反应机理探讨

与氯代烯烃或芳烃相反, 氯代膦烯与零价钯的氧化加成反应可以在温和条件下进行. 提出了可能的反应机理. 起始卤代膦烯的结构决定了反应历程和最终产物的结构.     

Microwave-assisted,montmorillonite K-10 catalyzed three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones under solvent-free conditions

An efficient, rapid, and green synthesis of 2H-indazolo[2,1-b]phthalazine-triones has been accomplished under solvent-free conditions by the reaction of phthalhydrazide, aldehydes and 5,5-dimethylcyclohexane-1,3-dione. This approach exploits the synthetic potential of microwave irradiation and Montmorillonite K-10 combination and offers many advantages, such as excellent product yields, shorter reaction time, reusable catalyst, easy isolation of products, and environmentally benign reaction conditions.     

Synthesis of N-heteroaromatic onium betaines of indane-1,3-dione

Betaines are formed in good yields in the reaction of N-heteroaromatic compounds with 2-dicyanomethyleneindane-1,3-dione oxide and its 4- and 5-halo derivatives in dioxane. The corresponding oxides were obtained by oxidation of 2-dicyanomethyleneindane-1,3-dione and its 4- and 5-substituted derivatives with hydrogen peroxide in dioxane. Data from the IR spectra of the compounds are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 889–892, July, 1978.     

微波辐射下无催化剂一锅法合成N-甲基十氢吖啶-1,8-二酮化合物

为了研究从简单易得的原料在无催化剂的条件下一锅法合成N-甲基十氢吖啶-1,8-二酮化合物，我们以各类醛（脂肪醛、芳香醛、二醛）、达咪酮或1,3-环己二酮和甲胺为原料，以乙二醇或水为溶剂，经微波辐射，一步反应得到了一系列N-甲基十氢吖啶-1,8-二酮化合物。反应时间从传统热反应的4-5小时缩短至2-10分钟，产率较高（56-95%），并且不需要使用催化剂。该反应后处理方便，只需要简单洗涤，环境友好，为合成此类化合物提供了一种简便、有效的合成方法。该方法不仅适用于一元脂肪醛、芳香醛，还适用于芳香二醛，因此可以合成含有一个或两个十氢吖啶结构单元的杂环化合物。     

N,N′-Cyclization of carbodiimides with 2-(bromomethyl)acrylic acid. A direct entry to the system 5-methylene-6H-pyrimidine-2,4-dione,a new class of thymine analogues

Carbodiimides react under very mild conditions with 2-(bromomethyl)acrylic acid at both N atoms to give 1,3-disubstituted-5-methylene-6H-pyrimidine 2,4-dione derivatives in moderate to good yields. These products behaved as good Michael acceptors towards a variety of nucleophiles such as bromine, hydrochloric acid, hydrides, etc. A plausible mechanism is proposed based on theoretical approaches and experimental results.     

Efficient One-Pot Synthesis of Tetrahydrobenzo[c]xanthene-1,11-dione Derivatives Under Microwave Irradiation

An efficient one-pot condensation of 4-hydroxylcoumarin, aromatic aldehydes, and 5,5-dimethylcyclohexane-1,3-dione has been achieved with molecular iodine as a catalyst via conventional heating and microwave irradiation techniques, and thus a variety of new tetrahydrobenzo[c]xanthene-1,11-dione derivatives were prepared in good yields.     

A one-pot reaction of (chlorocarbonyl) phenyl ketene with β-ketoamides and thiochromen-2-one

Readily available (chlorocarbonyl)phenyl ketene and a varied set of β-ketoamides were reacted in a one-step procedure to produce 2-pyrone derivatives. β-Ketoamide derivatives are versatile intermediates for the synthesis of heterocyclic compounds. For instance, 1-morpholino-3-phenyl-1,3-propanedione, 1-phenyl-3-piperidino-1,3-propanedione, 1-phenyl-3-pyrrolidino-1,3-propanedione, 1-piperidino-1,3-butanedione, 1-morpholino-2-phenyl ethanone were used in these reactions to produce 2-pyrone derivatives. In addition, the preparation of 4-hydroxy-3-phenylthiochromeno[4,3-b]pyran-2,5-dione derivatives and 4-hydroxy-7-methyl-3-phenyl pyrano[3,2-c]chromeno-2,5-dione were described. For the synthesis of these compounds 4-hydroxy-2H-thiochromen-2-ones and 4-hydroxy-8-methyl-2H-chromen-2-one were reacted with (chlorocarbonyl)phenyl ketene and the final products were isolated in good yields.     

Microwave-Assisted,Multicomponent, Ecofriendly Synthesis of 3-Bihetaryl-2-oxindole Derivatives Grafted with Phenothiazine Moiety

A series of 3-(3′-pyrrolyl)-2-oxindoles incorporating the phenothiazine moiety has been synthesized under both conventional and microwave heating conditions via multicomponent reaction of 3-(2-(phenothiazin-2-yl)-2-oxoethylidene)-2-oxindole derivatives, acyclic and cyclic 1,3-dicarbonyl compounds, and ammonium acetate. The resulting 2-oxindole derivatives underwent selective chloroacetylation at both the oxindole and the phenothiazine NH groups. Treatment of the dichloroacetylated compound with 2 mol of sodium azide in acetone under reflux gave the corresponding monoazide with concomitant dechloroacetylation of the N-chloroacetyl group of the oxindole ring. Huisgen 1,3-dipolar cycloaddition of the resulted alkyl azide with diethyl acetylene–dicarboxylate afforded the corresponding triazole derivative in good yield. Furthermore, the dichloroacetylated compound could be easily cyclized into 4-(3-oxo-2,3-dihydroxazolo[3,2-a]indol-9-yl)-1H-pyrrole-3-carboxylate derivative by treatment with sodium hydride in dry toluene. The yields and rate of reactions significantly improved under microwave heating conditions.     

Microwave Assisted Synthesis of Pyridone Derivatives

A series of pyridone derivatives were synthesized by the reaction of aromatic aldehydes, 1,3‐dicarbonyl compounds and ammonium acetate under microwave irradiation in the absence of solvent. The reactions were completed within 3‐5 min to give the desired products in 72.4‐86.2% yields.     

Allylsilane and diallylsilane reactions with functionalized ethylene ketals or benzodioxoles

The bis-allylation of ethylene ketal and catechol ketal derivatives of 2,5-hexanedione occurred with a great stereoselectivity. The tetraallylation of bis-catechol ketal derivatives of 2,5-hexanedione and 2-methyl-1,3-cyclohexanedione or the diallylation of 4-phenylbutan-2-one derivatives arise in good yields and these compounds were suitable substrates for ring-closing metathesis leading to 4,4-dialkylcyclopentenes. Condensation of 1,8-bistrimethylsilyl-2,6-octadiene (Bistro) with 4-phenylbutan-2-one catechol ketal derivatives or 2-methylcyclohexan-1,3-dione mono catechol ketal afforded in good yields cyclic and tricyclic products 12 or 23, respectively.     

A practical access to novel 2-amino-5-arylidene-1,3-thiazol-4(5H)-ones via sulfur/nitrogen displacement under solvent-free microwave irradiation

A new effective approach to the synthesis of a small library of 2-amino-5-arylidene-1,3-thiazol-4(5H)-ones was reported using solvent-free reaction conditions under microwave irradiation. In the first step, rhodanines were subjected to Knoevenagel condensation with aryl aldimines according to a facile one-pot protocol. Then the (5Z)-5-arylidene rhodanine derivatives were transformed directly into the corresponding 2-amino-1,3-thiazol-4(5H)-ones by sulfur/nitrogen displacement reaction under microwaves with retention of configuration and good overall yields.     

Synthesis of 2-substituted 5-(1,3-dithiolan-2-ylidene)-1,3-dioxane-4,6-dione derivatives

Some 2-substituted 5-(1,3-dithiolan-2-ylidene)-1,3-dioxane-4,6-dione derivatives 3 were prepared from the condensation reaction of 1,3-dithiolan-2-ylidenemalonic acid ( 2 ) with carbonyl compounds in 40–93% yields.     

3-芳氧基-1-丙胺类HIV-1 Tat/PCAF BRD抑制剂的合成及生物活性

为了研究HIV-1 Tat/PCAF BRD抑制剂的构效关系, 合成了6个3-芳氧基-1-丙胺类化合物. 以取代的2-硝基苯酚为起始原料, 在常规加热和微波辐射加热下与1,3-二溴丙烷反应合成3-(2-硝基芳氧基)-1-溴丙烷(3), 结果显示, 微波辐射加热比常规加热下的反应速度明显加快, 收率有所提高. 3和邻苯二甲酰亚胺钾进行N-烷基化反应合成了2-[3-(芳氧基)-丙基]二氢异吲哚-1,3-二酮, 再经肼解得到了目标化合物, 所有化合物的结构均经FTIR, ¹H NMR, ¹³C NMR及HRMS确证. ELISA检测法测定了它们体外抑制HIV-1 Tat/PCAF BRD的活性, 并对影响活性的因素进行了讨论.     

A One Pot Synthesis of 5-Phenyl-1,3-Dioxane-4,6-Dione Derivatives

A general procedure for synthesis of 5-phenyl-1,3-dioxane-4,6-dione derivatives is described. The synthesis involves the cycloaddition of (α-chlorocarbonyl)phenyl ketene with carbonyl compounds to generate the corresponding substituted 2-oxetanone's which is readily transformed to the final products in one step. The 1,3-dioxane-4,6-dione is a rigid cyclic structure, and can undergo easy hydrolysis.     

微波辐射下一步合成9-芳基-1,2,3,4,5,6,7,8,9,10-十氢-1,8-吖啶二酮

以芳醛、1,3-环己二酮、醋酸铵为原料在无溶剂条件下经微波辐射合成了一系列9-芳基-1,2,3,4,5,6,7,8,9,10-十 氢-1,8-吖啶二酮. 该反应的反应时间短、产率高、环境友好、后处理方便. 产物的结构经红外光谱、核磁共振谱表征, 3d的结构经单晶X射线衍射进一步确证.     

Reaction of iodonium ylides of 1,3-dicarbonyl compounds with HF reagents

Reaction of dibenzoylmethane with (diacetoxyiodo)benzene in the presence of KOH in MeCN quantitatively gave the corresponding iodonium ylide, which was treated with a HF reagent to afford the corresponding 2-fluorinated dibenzoylmethane in 14-50% yields. The similar reaction of the iodonium ylides obtained from 1-phenylbutan-1,3-dione, ethyl benzoylacetate, and ethyl p-nitrobenzoylacetate with TEA·3HF gave the corresponding fluorinated products in 17-34% yields. It is suggested that the fluorinated products were formed through the C-protonation of the ylide, followed by displacement with fluoride ion. The same reaction of the iodonium ylide of dibenzoylmethane with concentrated HCl gave the corresponding chlorinated product in 45% yield.     

Iridium catalyzed alkylation of 2′-hydroxyacetophenone with alcohols under thermal or microwave conditions

2′-Hydroxyacetophenone was alkylated with a range of substituted benzyl and heteroaryl alcohols to afford the corresponding C-alkylated products in good yields under microwave irradiation. The C-alkylated products were reacted with bromoacetonitrile to afford 2-amino-3-benzyl 1,4-naphthoquinone derivatives in moderate yields.