Synthesis of 2-spiro-(1,2-dihydroperimid-2-yl)-5,5-dialkyl-2,3,5,6-tetrahydropyrrolo[2,1-a]-isoquinolin-3-ones

2,3-Dioxpyrrolo[2,1-a]isoquinolines react with 1,8-naphthalenediamine in 2-propanol in the presence of p-toluenesulfonic acid to give 2-spiro-(1,2-dihydroperimid-2-yl)-5,5-dialkyl-2,3,5,6-tetrahydro-pyrrolo[2,1-a]isoquinolin-3-ones whose structure was confirmed by X-ray analysis. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1849–1854, December, 2008.     

Imidazo[1,2-a]pyridines. I. Synthesis and inotropic activity of new 5-imidazo[1,2-a]pyridinyl-2(1H)-pyridinone derivatives

A series of 1,2-dihydro-5-imidazo[1,2-a]pyridinyl-2(1H)-pyridonones was synthesized and evaluated for positive inotropic activity, 1,2-Dihydro-5-imidazo[1,2-a]pyridin-6-yl-6-methyl-2- oxo-3-pyridinecarbonitrile (11a) hydrochloride monohydrate (E-1020) was found to be a potent and selective inhibitor of phosphodiesterase III and a long-acting, potent, orally active positive inotropic agent. Additional imidazo[1,2-a]pyridin-2-yl (3a), -3-yl (16), -7-yl (20) and -8-yl (24a) compounds were also prepared. Altering the pyridine substitution from the 2-position to the 6-position produced a 2-fold increase in the i.v. cardiotonic potency (ED50) from 52 to 23 micrograms/kg, while substitution at the 3-, 7- or 8-position reduced potency. In the 2-positional isomers, introduction of halogen groups enhanced the activity and 3-chloro-1,2-dihydro-5-(6-fluoroimidazo[1,2-a] pyridin-2-yl)-6-methyl-2(1H)-pyridinone (3u) was the most potent (i.v. ED50 11 micrograms/kg) in this series. E-1020 is presently under development for the treatment of congestive heart failure.     

Preparation and reactions of some 1,2,3,4-Tetrahydro-2,3-disubstituted 7(or 8)hydroxy-1,4-dioxopyrazino[1,2-a] indoles

1,2,3,4-Tetrahydro-2,3-disubstituted 7(or 8) hydroxy-1,4-dioxopyrazino[1,2-a]indoles have been prepared by the condensation of 6(or 5)benzyloxyindole-2-carbonyl chloride with d1-N- alkylamino acid ethyl esters in the presence of triethyl amine followed by the hydrogenolysis over palladium-carbon. Methylation and alkaline hydrolysis of 1,2,3,4-tetrahydro-2-benzy1-1,4-dioxopyrazino[1,2-a]indole are discussed.     

Synthesis and pharmacological activity of 2-(biphenyl-4-yl)imidazo[1,2-a]benzimidazoles

Russian Chemical Bulletin - An efficient method for the synthesis of novel 9H-imidazo[1,2-a]benzimidazole derivatives containing a biphenyl substituent at position 2 was developed. These compounds,...     

Research on imidazo[1,2-a]benzimidazole derivatives. 22. Synthesis of 2,3-dihydroimidazo[1,2-a]benzimidazoles starting from 2-imino-3-(2-hydroxyethyl)benzimidazolines

A -elimination reaction with the formation of 2-imino-3-vinylbenzimidazolines occurs simultaneously with intramolecular alkylation and the formation of an imidazoline ring in the action of alcoholic alkali on 2-imino-3-(2-chloroethyl) benzimidazolines. The thermolysis of 3-chlorethyl-substituted imines without a solvent or in an inert solvent leads exclusively to 2,3-dihydroimidazo[1,2-a] benzimidazoles. An attempt to obtain the latter directly from 2-imino-3-(2-hydroxyethyl) benzimidazolines by the action of a mixture of thionyl chloride and acetic anhydride on them also leads to ambiguous results.See [1] for communication 21.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 918–925, July, 1986.     

New Synthesis of peri-Fused Tetrahydro[1,3]diazepino[1,2-a]benzimidazoles from 1-Aroylmethyl-2-[(4-hydroxybutyl)amino]benzimidazoles

Russian Journal of Organic Chemistry - Treatment of 2-[(4-hydroxybutyl)amino]-1H-benzimidazole with ω-bromoacetophenones gave 1-aroylmethyl-substituted derivatives which underwent cyclization...     

Efficient Synthesis of New Tetracyclic Benzofuro[3,2-d]-imidazo[1,2-a] pyrimidine-2,5-(1 H,3 H)-diones

The aza‐Wittig reaction of iminophosphorane ( 1 ) with aromaic isocyanates gave carbodiimides ( 2 ), which were allowed to react further with (‐amino ester in the presence of a catalytic amount of sodium ethoxide to give selectively new tetracyclic benzofuro[3,2‐d]imidazo[1,2‐a]pyrimidine‐2,5‐(1H,3H)‐diones ( 5 ) in good yields. X‐ray structure analysis of 5i verified the proposed structure and the reaction selectivity.     

Pyrrolo [1,2-a] [1,3,5] triazine-2,4(1H, 3H)-diones. III—Fragementation under electron-impact

The mass spectra of eight pyrrolo[1,2-a][1,3,5]triazie-2,4(1H, 3H)-diones have been examined. An unusual feature in the fragmentation of those compounds having a 7-alkoxycarbonyl function, namely loss of the whole ester grouping with concomitant hydrogen rearrangement, is discussed.     

Synthesis of pyrimido[1,2-a]benzimidazoles from ethyl 2-ethoxymethylidene-3-oxo-3-(polyfluoroalkyl)propionates

Cyclization of ethyl 2-ethoxymethylidene-3-oxo-3-polyfluoroalkylpropionates with benzimidazol-2-amine in boiling 1,4-dioxane followed two concurrent pathways with participation of fluoroacyl and ethoxycarbonyl fragments and formation of, respectively, ethyl 4-hydroxy-4-polyfluoroalkyl-1,4-dihydropyrimido-[1,2-a]benzimidazole-3-carboxylates and 3-polyfluoroacylpyrimido[1,2-a]benzimidazol-4-ols. Dihydropyrimido[1,2-a]benzimidazole derivatives undergo dehydration to give ethyl 4-(polyfluoroalkyl)pyrimido[1,2-a]benzimidazole-3-carboxylates, whereas the hydroxy group in 3-polyfluoroacylpyrimido[1,2-a]benzimidazol-4-ols is capable of being replaced by the amino group of the second benzimidazole molecule with formation of 4-(1H-benzimidazol-2-ylamino)-3-polyfluoroacylpyrimido[1,2-a]benzimidazoles.     

Chemistry of acyl(imidoyl)ketenes. 8*. Thermolysis of 3-alkoxycarbonyl- 5-phenyl-1,2,4,5-tetrahydropyrrolo[1,2-a]- quinoxaline-1,2,4-triones. Structure of 2-(3-oxo-4-phenyl-3,4-dihydro-2-quinoxalinyl)- 2,4-di(ethoxycarbonyl)-6-phenyl-2,3,5,6-tetrahydro- 1h-pyrido[1,2-a]quinoxaline-1,3,5-trione

3-Alkoxycarbonylmethylene-1-phenyl-1,2,3,4-tetrahydro-2-quinoxalones, obtained by the interaction of dialkyl esters of oxaloacetic acid and N-phenyl-o-phenylenediamine, react with oxalyl chloride with the formation of 3-alkoxycarbonyl-5-phenyl-1,2,4,5-tetrahydropyrrolo[1,2-a]quinoxaline-1,2,4-triones. Alkoxycarbonyl(2-oxo-1-phenyl-1,2-dihydro-3-quinoxalinyl)ketenes, generated on thermal decarbonylation of the latter, are stabilized by participation in a [4+2] cyclodimerization reaction with the formation of 2,4-di(alkoxycarbonyl)-2-(3-oxo-4-phenyl-3,4-dihydro-2-quinoxalinyl)-6-phenyl-2,3,5,6-tetrahydro-1H-pyrido[1,2-a]quinoxaline-1,3,5-triones. The crystal and molecular structure of the di(ethoxycarbonyl) derivative have been investigated by X-ray structural analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1501–1506, October, 2004.     

The thermal decomposition of 1,1′-azo-4,4′-di(N-methylanilino) pyridinium dibromide dihydrate and 1,1′-azo-3,3′-dimethyl-2,2′-diphenylimidazo [1,2-a] pyrimidinium dibromide tetrahydrate

The thermal decomposition of 1,1′-azo-4,4′-di(N-methylanilino) pyridinium dibromide dihydrate (A) and 1,1′-azo-3,3′-dimethyl-2,2′-diphenylimidazo [1,2-a] pyrimidinium dibromide tetrahydrate (B), and the mass spectra of their volatile products, are described. The results show that the water of crystallisation can be

removed from (A) without causing rupture of the tetrazene linkage, but that loss of water from (B) caused breakdown of the molecule. 4-(N-methylanilino)pyridine hydrobromide was the major product formed from (A) after the rupture of the tetrazene linkage, and 3-methyl-2-phenyl imidazo [1,2-a] pyrimidine hydrobromide (F) was formed from (B).     

Cu(I)-catalyzed synthesis of imidazo[1,2-a]pyridines from aminopyridines and nitroolefins using air as the oxidant

A copper-catalyzed method for the synthesis of imidazo[1,2-a]pyridines with aminopyridines and nitroolefins using air as oxidation agent in a one-pot procedure has been developed. In this process, the reaction appears to be very general and suitable for construction of a variety of imidazo[1,2-a]pyridines.     

Investigations in the imidazole series LXXIII. Synthesis of pyrrolo[1,2-a]benzimidazole derivatives from 2-alkyl(aralkyl)benzimidazoles

The synthesis of 2-alkyl(aryl)- and 2-aryl-3-alkyl(aryl)-4-acylmethyl-substituted pyrrolo-[1,2-a]benzimidazoles was accomplished by the reaction of 2-alkyl(aralkyl)benzimidazoles with -haloketones and subsequent cyclization of the resulting 1,3-(diacylmethyl)-2-alkyl-(aralkyl)benzimidazolium halides.See [1] for communication LXXII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 403–404, March, 1972.     

A practical two-step synthesis of imidazo[1,2-a]pyridines from N-(prop-2-yn-1-yl)pyridin-2-amines

The Sandmeyer reaction of differently C-2 substituted N-(prop-2-yn-1-ylamino)pyridines is an efficient, mild, new and practical method for the stereospecific synthesis of (E)-exo-halomethylene bicyclic pyridones bearing the imidazo[1,2-a]pyridine heterocyclic ring system.     

N-(2-Phenoxy)ethyl imidazo[1,2-a]pyridine-3-carboxamides containing various amine moieties: Design,synthesis and antitubercular activity

Seven 2,6-disubstituted N-(2-phenoxy)ethyl imidazo[1,2-a]pyridine-3-carboxamide series containing various amine moieties were designed and synthesized as new anti-TB agents.Many of them show excellent in vitro activity against both drug-sensitive MTB strain H37Rv and two MDR-MTB clinical isolates(MIC:<0.002-0.030 μg/mL).Compounds 2f,5e and 5g display acceptable safety and pharmacokinetic profiles,opening a new direction for further development.     

Cobalt(II) complexes of 5,7-dimethyl[1,2,4]-triazolo-[1,5-a]-pyrimidine. Spectroscopic characterization,XRD study and antimicrobial activity

Summary Several cobalt(II) complexes of 5,7-dimethyl-[1,2,4]-tria-zolo-[1,5-a]-pyrimidine (DMTP) have been prepared and characterized by thermal and spectroscopic techniques. The crystal structure of [Co(DMTP)₂(H₂O)₄]Br₂·2H₂O has been determined by XRD; the metal ion is octahedrally coordinated by two DMTP ligands through the usual N(3) site and four water molecules. Metal binding to N(3) for DMTP is consistent with the electronic properties calculated with the MOPAC programme. All the complexes were screened for their activity against several types of bacteria, showing a broad-spectrum antimicrobial activity.     

Five-membered 2,3-dioxoheterocycles: LXXIII. Synthesis and thermolysis of 3-acylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones

Reactions of (Z)-3-(phenacylidene-2-oxo)-3,4-dihydroquinoxalin-2(1H)-ones and (Z)-3-(3,3-dimethyl-2-oxobutylidene)-3,4-dihydroquinoxalin-2(1H)-one with oxalyl chloride led to the formation of 3-acyl-1Hpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones that at the thermal decarbonylation generated acyl(3-oxoquinoxalin-2-yl)ketenes which underwent the intramolecular stabilization giving 3-acylfuro[3,2-b]quinoxalin-2(4H)-ones.