Synthesis of 1-｛ Imidazo[ 1,2-a ] pyridin-2-yl ｝ guaiazulenes

以1-氯乙酰基愈创兰烃奠和取代2-氨基吡啶为原料,一锅法合成了一系列未见文献报道的1-{2-咪唑[1,2-a]吡啶基}愈创兰烃薁衍生物,收率47％ ～ 74％,其结构经1H NMR,IR和元素分析表征.     

Iodine-catalyzed Efficient Synthesis of β-Keto Esters from Aldehydes and Ethyl Diazoacetate Under Solvent-free Conditions

An efficient procedure for the synthesis of β-keto esters from the reaction of aldehydes and ethyl diazoa-cetate catalyzed by iodine at room temperature under solvent-free conditions has been described. The catalytic procedure has the advantages of easily available catalyst,mild reaction conditions,high yields,and easy work-up.     

Microwave-prompted rapid and efficient synthesis of 3-alkyl substituted imidazo[1,5-a]pyridines

Under regular heating and microwave irradiation, 3-alkyl substituted imidazo[1,5-a] pyridines were synthesized from 2,2＇- pyridil, di-2-pyridyl ketone and aliphatic aldehydes in the presence of ammonium acetate and acetic acid. Compared to the traditional heating condition, the reaction time under microwave irradiation was shorter and 3-alkyl imidazo[1,5-a]pyddines were given in higher yield.     

One-pot synthesis of novel pyrido[2,3-d]pyrimidines using HAp-encapsulated-γ-Fe2O3 supported sulfonic acid nanocatalyst under solvent-free conditions

Novel pyrido[2,3-d]pyrimidine derivatives were synthesized through a one-pot three-component approach using HAp-encapsulated-γ-Fe2O3[γ-Fe2O3@HAp-SO3H]catalyzed condensation of 6-arnino-2-（methylthio or ethylthio）pyrimidin-4（3H）-one,Meldrum＇s acid and aryl aldehydes at 60 ℃ and under solvent-free conditions.In this protocol the use of nanocatalyst provided a green,useful and rapid method to generate the products in short reaction times and excellent yields（88%-94%）.     

水相中微波辅助合成咪唑并[1,2-α]吡啶衍生物的研究

开展了水相中硝基烯烃与氨基吡啶反应生成咪唑并[1,2-α]吡啶衍生物的微波辅助合成研究。结果表明:相同反应时间,在微波辅助条件下,生成咪唑并[1,2-α]吡啶衍生物的速率较常规加热条件下增大。一系列咪唑并[1,2-α]吡啶衍生物被高效的合成出来,最高产率达到85%。产物结构经~1H NMR,~(13)C NMR及MS得到确证。该方法具有产率高、操作简单、环境友好等优点。     

1-{2-咪唑[1,2-a]吡啶基}愈创兰烃薁的合成

以1-氯乙酰基愈创兰烃薁和取代2-氨基吡啶为原料,一锅法合成了一系列未见文献报道的1-{2-咪唑[1,2-a]吡啶基}愈创兰烃薁衍生物,收率47%～74%,其结构经1H NMR,IR和元素分析表征。     

Design, Synthesis and Pregnancy-Terminating Activity of 2-Aryl Imidazo[2,1-a]isoquinolines

Introduction Symmetrical trizol bioisosterisms, such as 2-aryl pyrazolo[5,1-a]isoindoles and isoquinolines, pyrazolo- [1,5-a]indoles and quinolines, 2-aryl imidazo[2,1-a]- isoquinolines and isoindoles, 3,5-diaryl-s-triazoles, were shown to be active as non-hormonal post-implantation contragestational agents in various animal species after parenteral administration.1-7 Some compounds had good oral activity.8 Among them, DL204-IT9 [2-(3-ethoxy- phenyl)-5,6-dihydro-s-triazole[5,1-a]isoquinoline…     

2-吡啶基咪唑并[1,2-a]吡啶的水中合成

2-乙酰基吡啶1经溴化反应后得到2-(2-溴乙酰基)吡啶氢溴酸盐2,2在水中与NaHCO3发生中和反应生成2-(2-溴乙酰基)吡啶,不经分离直接于水中和2-氨基吡啶衍生物3a-3h反应生成2-吡啶基咪唑并[1,2-a]吡啶4a-4h.采用核磁共振谱仪、红外光谱仪及质谱仪表征了产物的结构.结果表明,利用该方法可以在温和的反应条件下高产率得到目标产物,且方法操作简便、对环境友好.     

Synthesis of 2-Arylimidazo[1, 2-a]pyrimidines in Ionic Liquids

Room temperature ionic liquids were used as a “green“ recyclable alternative to conventional solvents in the synthesis of pharmaceutically useful compounds 2-arylimidazo[1, 2-a]pyrimidines through Tschotschibabin reaction of a-bromoacetophenones with 2-aminopyrimidine in good yields.     

One-pot synthesis of pyrrolo[1,2-a]quinoxaline and pyrrolo[1,2-a]pyrazine derivatives via the three-component reaction of 1,2-diamines,ethyl pyruvate and α-bromo ketones

A simple synthetic protocol has been developed involving the three-component reaction between 1,2-diamines, ethyl pyruvate and a-bromo ketones in the presence of Fe Cl3 as a catalyst. A number of pyrrolo[1,2-a]quinoxaline and pyrrolo[1,2-a]pyrazine derivatives were synthesized in excellent yields using this protocol.     

Efficient One-pot Synthesis of 12-Aryl-8, 9, 10, 12-tetrahydrobenzo[a]xanthen-11-ones Under Solvent-free Conditions

Multi-component condensation of 2-naphthol, aromatic aldehydes, and cyclic 1,3-dicarbonyl compounds catalyzed by ionic liquid [NSPTEA][HSO₄] was accomplished for the synthesis of a series of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones under solvent-free conditions. High yields, ease recovery, short reaction time and reusability of catalyst are significant advantages. ZrOCl₂·8H₂O was also found to act as an effective catalyst towards this transformation.     

Efficient One-pot Synthesis of Pyrrolo[2,1-a]isoquinoline and Pyrrolo[1,2-a]quinoline Derivatives

A one-pot sequential reaction for efficient synthesis of pyrrolo[2,1-a]isoquinoline and pyrrolo[1,2-a]-quinoline derivatives has been developed. The reaction included firstly the Cu-catalyzed three-component reaction of isoquinoline(quinoline), acetylenedicarboxylate and alkynylbenzene and then Cs₂CO₃-promoted intramolecular cyclization reaction of initially formed 1-alkenyl-2-alkynyl-1,2-dihydroisoquinoline(1,2-dihydroquinoline).     

Copper-catalyzed three-component reaction of imidazo[1,2-a]pyridine with elemental sulfur and arylboronic acid to produce sulfenylimidazo[1,2-a]pyridines

A copper-catalyzed three-component reaction for the synthesis of sulfenylimidazo[1,2-a]pyridines using elemental sulfur as the sulfenylating agents has been developed.     

One-pot Synthesis of 3-Aminoimidazo[1,2-a]pyridines Catalyzed by Heteropolyacids

Condensation of aldehydes, isonitriles and 2‐aminopyridines in the presence of H₃PMo₁₂O₄₀ affords different derivatives of 3‐aminoimidazo[1,2‐a]pyridine in good to excellent yields.     

Ammonium chloride catalyzed one-pot synthesis of imidazo[1,2-a]pyridines

Ammonium chloride as a very inexpensive and readily available reagent efficiently catalyzes one-pot, three-component Groebke condensation reactions of aldehydes, isocyanides, and 2-aminopyridines or 2-aminopyrimidines in methanol to afford the corresponding imidazo[1,2-a]pyridines in high yields at room temperature. Correspondence: Ahmad Shaabani, Department of Chemistry, Shahid Beheshti University, PO Box 19396-4716, Tehran, Iran.     

Solvent-dependence of KI Mediated Electrosynthesis of Imidazo[1,2-a]pyridines

Iodized salts are widely used as mediators to promote C—H functionalization. Solvents and additives have been described as significant roles in these reactions. However, the further electrochemical investigations have rarely been reported. Herein, a KI mediated electrochemical annulation between acetophenones and 2-amniopyridines was developed. We revealed the effect of acids and solvents by cyclic voltammetry(CV), differential pulse voltammetry(DPV), and square wave voltammetry(SWV). The oxidation of 2-aminopyridine is inhibited at the potential window with the addition of strong acids, and the lowest oxidation potential difference of KI was obtained by utilizing EtOH as solvent. The experimental studies also show that the mixture solvent of EtOH/DMSO(9/1, volume ratio) facilitates the electrochemical cyclization due to the solubility improvement of KI. CF₃SO₃H has been screened as the optimal acid. A range of Imidazo[1,2-a]- pyridines have been synthesized in yields of 42% to 96%. Electrochemical investigations present that the KI mediated electro- chemical reaction is probably solvent-dependence.     

Formylation of Furyl-substituted Imidazo[1,2-a]pyridine, Imidazo[1,2-a]pyrimidine and Imidazo[2,1-b]thiazole

Vilsmeier formylation of 2-(2-furyl)-substituted imidazo[1,2-a]pyridine and imidazo[1,2-a]pyrimidine, and also 6-(2-furyl)imidazo[2,1-b]thiazole with 1 mole of reagent occurs at the free position of the imidazole ring, while with an excess of the reagent it also occurs at the position 5 of the furyl group.     

Synthesis of 2,3-Dihydroimidazo[1,2-a]pyridines from 1,3-Diketones

A series of 2-hydroxy-, 2-chloro-, and 2-(2-hydroxyethylamino)-6-aryl-4-polyfluoroalkyl-3-cyanopyridines has been synthesized. The latter react with phosphorus oxychloride to give fluorine containing 2,3-dihydroimidazo[1,2-a]pyridines.     

Synthesis of 6-alkylthioimidazo[1,2-a]pyridines

A number of 6-alkylthio(and sulfonyl)-substituted imidazo[1,2-a]pyridines were synthesized by the reaction of 5-alkylthio- and 5-alkylsulfonyl-2-aminopyridines with -bromoacetophenone and -chlorocyclohexanone in order to search for new compounds that have fungicidal activity. 5-Alkylthio-2-aminopyridines were obtained from the double salt of 5-mercapto-2-aminopyridine with SnCl₂ and HCl by reaction with alkyl halides or tert-C₄H₉OH and 75% H₂SO₄. 5-tert-Butylthio-2-aminopyridine was oxidized by means of KMnO₄ to 5-tert-butylsulfonyl-2-aminopyridine. A double salt was synthesized from 2-aminopyridine-5-sulfonic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 634–638, May, 1979.