Modification of biologically active amides and amines with the fluorine-containing heterocycles 9. γ-Carbolines modified by the 2-trifluoromethylimidazo-[1,2-a]pyridin-6-yl fragment

γ-Carbolines can act as nucleophiles efficiently replacing the fluorine atom in 3-fluoro-2-trifluoromethylimidazo[1,2-a]pyridines in the presence of KOH. Radioligand binding method was used to study the influence of the synthesized N-modified carbolines on the neuronal NMDA-receptors.     

Modification of biologically active amides and amines with fluorine-containing heterocycles 8. γ-Carbolines modified with the 2-(2-trifluoromethylimidazo[1,2-a]pyridin-6-yl)ethyl fragment

An approach to modification of biologically active g-carbolines with the 2-(2-trifluoromethylimidazo[1,2-a]pyridin-6-yl)ethyl fragment was proposed. The modification involves a reaction of 2-trifluoromethyl-6-vinylimidazo[1,2-a]pyridine with g-carbolines. The effect of the compounds obtained on neuronal NMDA receptors was studied by the radioligand binding method.     

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.     

Unexpected Recyclization of 1H-δ-Carbolines to Pyrrolo[1,2-a]indoles

When 1H-2-methyl-1-p-nitrophenyl-3-ethoxycarbonylpyrido[3,2-b]indole (1) is heated in alcoholic solutions of ammonia, we observe a previously unknown recyclization leading to formation of 2-alkoxycarbonyl-3-methyl-9-p-nitrophenylimino-9H-pyrrolo[1,2-a]indoles (3,6).     

Synthesis of 11-aryl-11H-indeno[1′,2′:4,5]imidazo[1,2-a]pyridines via dehydrative cyclization of aryl(2-arylimidazo[1,2-a]pyridin-3-yl)methanols

A series of 11-aryl-11H-indeno[1′,2′:4,5]imidazo[1,2-a]pyridines was obtained via AlCl₃-promoted, dehydrative cyclization of the corresponding aryl(2-arylimidazo[1,2-a]pyridin-3-yl)methanols in moderate to good yields. The synthesized compounds can be considered as conformationally restricted, privileged aza-heterocyclic scaffold bearing triarylmethane analogs.     

Rapid and efficient one-pot microwave-assisted synthesis of 2-phenylimidazo[1,2-a]pyridines and 2-phenylimidazo[1,2-a]quinoline in water–PEG-400

An effective, expeditious, environmentally benign one-pot synthesis of 2-phenylimidazo[1,2-a]pyridines and 2-phenylimidazo[1,2-a]quinoline from easily available starting materials as aromatic carbonyl compound, 2-amino pyridine, succinamide, and in situ generated α-iodo acetophenone in combination with green solvent PEG-400 and water (2:1) under microwave irradiation. The newly developed protocol with excellent yield of product in very short time of reaction by avoiding the use of lachrymatric α-chloro and α-bromocarbonyl compounds, volatile, toxic organic and hazardous solvents, reagents is the advantage of this research work. The final products were confirmed by their characterization data such as ¹H NMR, ¹³C NMR, high resolution mass spectrometry (HRMS) and were compared with its reported method.     

Dipyrrolo[1,2-a; 2′,1′-c]pyrazines. 4. Aminomethylation of alkyl substituted dipyrrolo[1,2-a; 2′,1′-c]pyrazines and 5,6-dihydrodipyrrolo[1,2-a; 2′,1′-c]pyrazines

We have studied the aminomethylation reaction of alkyl substituted dipyrrolo[1,2-a; 2,1-c]pyrazines and their 5,6-dihydro analogs using different aminomethylating agents. Use of alkoxydialkylaminomethanes (aminoacetals) as Mannich reagents leads to the highest yields of the aminomethylated dipyrrolopyrazines. The compounds prepared have been studied by mass spectrometry.For Communication 3, see [1].M. V. Lomonosov State University, Moscow 119899. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 949–957, July, 1998.     

Synthesis of Substituted Pyrido[1,2-a]benzimidazoles by Ruthenium-Catalyzed C−H Bond Activation and Tandem Cyclization of 2-Arylimidazo[1,2-a]pyridines with Iodonium Ylides

Ruthenium-catalyzed C−H bond activation and tandem cyclization of 2-arylimidazo[1,2-a]pyridines with iodonium ylides proceed efficiently. For the first time, the easily available iodonium ylides and inexpensive ruthenium complex were employed to synthesize pyrido[1,2-a]benzimidazole derivatives in good yields under simple and easy-to-operate conditions. Several primary mechanism investigations and synthetic applications involving gram-scale preparation, derivatization reactions and the transformation of iodonium ylide generated in situ have also been conducted.     

Dipyrrolo[1,2-a; 2′,1′-c]pyrazines. 5. Azo coupling of dipyrrolo[1,2-a;2′,1′-c]pyrazines and 5,6-dihydrodipyrrolo[1,2-a; 2′,1′-c]pyrazines

We have synthesized a series of previously unreported azo dyes via the azo coupling of alkyl substituted dipyrrolopyrazines with aryldiazonium chloride. For this type of substrate where one or both -positions of the pyrrole rings of the molecules are not occupied by substituents, electrophilic attack was found to occur initially at carbon atom C₍₃₎.For communication 4 see [1]M. V. Lomonosov State University, Moscow 119899, Russia Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 236–240, February, 1999.     

Diversity-Oriented Synthesis of [2.2]Paracyclophane-derived Fused Imidazo[1,2-a]heterocycles by Groebke-Blackburn-Bienaymé Reaction: Accessing Cyclophanyl Imidazole Ligands Library

This report describes the synthesis of a [2.2]paracyclophane-derived annulated 3-amino-imidazole ligand library through a Groebke-Blackburn-Bienaymé three-component reaction (GBB-3CR) approach employing formyl-cyclophanes in combination with diverse aliphatic and aromatic isocyanides and heteroaromatic amidines. The GBB-3CR process gives access to skeletally-diverse cyclophanyl imidazole ligands, namely 3-amino-imidazo[1,2-a]pyridines and imidazo[1,2-a]pyrazines. Additionally, a one-pot protocol for the GBB-3CR by an in situ generation of cyclophanyl isocyanide is demonstrated. The products were analyzed by detailed spectroscopic techniques, and the cyclophanyl imidazo[1,2-a]pyridine was confirmed unambiguously by single-crystal X-Ray crystallography. The cyclophanyl imidazole ligands can be readily transformed to showcase their useful utility in preparing N,C-palladacycles through regioselective ortho-palladation.     

Regioselective synthesis of 2-trivinylsilyl-2Н,3Н-[1,3]thia- and -selenazolo[3,2-a]pyridin-4-ium chlorides

Russian Chemical Bulletin -     

Heterocyclizations of Di- and Tricarbonyl Indole Derivatives. Synthesis of β-Carbolines, 3H-[1,2,5]Triazepino-[5,4-a]indol-4(5H)-one,and 5,10-Dihydro[1,2]diazepino-[4,5-b]indol-4(3H)-one

Russian Journal of Organic Chemistry - A synthetic approach to β-carbolines has been proposed on the basis of heterocyclization of ethyl 2-(2-benzoyl-1H-indol-3-yl)acetate with...     

Dipyrrolo[1,2-a; 2′,1′-c]pyrazines. 1. Quantum-chemical study of dipyrrolo[1,2-a; 2′,1′-c]pyrazines in electrophilic substitution reactions

The semiempirical quantum-chemical method PM3 has been used in a study of the electronic and spatial structure of dipyrrolo[l , 2-a; 2,1-cjpyrazines and 5,6-dihydrodipyrrolo[1,2-a; 2,1-cjpyrazines, and also their reactivities in electrophilic substitution reactions (protonation, acylation).M. V. Lomonosov Moscow State University, Moscow 119899 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1559–1565, November, 1995. Original article submitted September 13, 1995     

Synthesis of Substituted Imidazo[1,2-a]Pyridin-3-yl-Acetic Acids by Multicomponent Condensation of 2-Aminopyridines with Arylglyoxals and Meldrum’s Acid

Chemistry of Heterocyclic Compounds - A simple and effective method for the synthesis of substituted imidazo[1,2-a]pyridin-3-yl-acetic acids has been developed based on the multicomponent...     

Temperature-Gradient-Directed NMR Monitoring of a [3 + 3]-Cyclocondensation Reaction Between Alkynone and Ethyl 2-Amino-1H-indole-3-carboxylate Toward the Synthesis of Pyrimido[1,2-a]indole Catalyzed by Cs2CO3

We describe a NMR strategy to resolve temperature-gradient-monitored real-time chemical reaction involving a [3 + 3]-cyclocondensation reaction between alkynone and ethyl 2-amino-1H-indole-3-carboxylate toward the synthesis of pyrimido[1,2-a]indole catalyzed by Cs₂CO₃. The in situ NMR study clearly indicates that the reactant undergoes [3 + 3]-cyclocondensation reaction through a concerted mechanism, resulting in the product formation. The detailed NMR spectroscopic data led to the optimization of the reaction conditions and quantitative analysis of the product accurately and efficiently.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Synthesis of Angular [1,2,5]Oxadiazolo[3,4-b]pyrazino-[1′,2′ : 1,2]pyrrolo[2,3-e][1,4]diazepine by Stepwise Reaction of Pyrrolo[1,2-a]pyrazinetrione with 3,4-Diaminofurazan

Russian Journal of Organic Chemistry - Diaminofurazan reacted with 8-benzoyl-2-phenyl-3,4-dihydropyrrolo[1,2-a]pyrazine-1,6,7(2H)- trione to give addition product of the amino group to the double...     

Synthesis and Structure of 2-(1Н-Indol-1-yl)-6-ferrocenyl-4-(2-chloroimidazo[1,2-a]pyridin-3-yl)pyrimidine

A 2,4,6-trisubstituted pyrimidine including a 2-(1H-indol-1-yl) substituent was synthesized by the reaction of 1-ferrocenyl-3-(2-chloroimidazo[1,2-a]pyridin-3-yl)propanone with 2,5-dimethoxytetrahydrofuran. The structure of the synthesized compound was confirmed by IR and ¹Н NMR spectroscopy, and X-ray diffraction analysis. It has been shown that the ferrocene-containing compounds synthesized in the present work all demonstrate intramolecular charge transfer which is evidenced by the observation of the corresponding absorption bands with λ ^abs_max > 480 nm. The oxidation potential of ferrocene (E ^Fc_ox ) in all the compounds is higher than 700 mV.

     

Five-membered 2,3-dioxo heterocycles: XCVII. Reaction of 3-aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones with Fischer’s base

3-Aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones reacted with 1,3,3-trimethyl-2-methylidene-2,3-dihydro-1H-indole (Fischer’s base) to give (2Z)-1-aryl-2-[3-oxo-3,4-dihydroquinoxalin-2(1H)-ylidene]-5-(1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene)pentane-1,3,4-triones.     

Synthesis and Crystal Structure of 3-Phenyl-10b-benzyl-1,10b-dihydroimdazo[5,1-a]isoquinoline

Praziquantel, 2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-one, is a novel antiparasitic drug possessing one chiral center.[1] In the study of structure-activity relationship of praziquantel we were interested in its structural modification. 1-Benzyl Reissert compound of isoquinoline is required as starting materials for the synthesis of praziquantel analogues with modified chiral centers. On the other hand, we want to know what could be obtained when 1-benzyl Reissert compounds were exposed to high pressure catalytic hydrogenation. In this paper we report the results in the hydrogenation of 1-benzyl Reissert compound.