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1.
《合成通讯》2012,42(2):197-206
AbstractThe photocatalytic bromination of 2-arylimidazo[1,2-a]pyridines is described in this paper. This reaction uses the readily accessible and shelf-stable CBr4 as a bromine source. This photocatalytic system is shown to serve as a convenient and practical synthetic protocol for the preparation of 2-aryl-3-bromoimidazo[1,2-a]pyridines. 相似文献
2.
Cyclization of 1-allyl-2-amino-3-acylmethylbenzimidazolium halides under alkaline conditions gave 9-allyl-substituted imidazo[1,2-a]benzimidazoles. Cyclization of the same compounds on heating in concentrated hydrobromic acid was accompanied by addition
of hydrogen bromide at the exocyclic double bond. Competing cyclizations with participation of the 1-(2-bromopropyl) and 3-acylmethyl
substituents in 2-imino-2,3-dihydro-1H-benzimidazole were studied. Functionalization of the imidazo[1,2-a]benzimidazole system was performed via introduction of substituents into the 3-position and replacement of bromine in the
2-bromopropyl group in the 9-position. 相似文献
3.
L. Avallone M. G. Rimoli E. Abignente 《Monatshefte für Chemie / Chemical Monthly》1996,127(8-9):947-953
Summary Prompted by the remarkable pharmacological activity shown by the corresponding carboxylic acids and other analogues, a series of 2-phenylimidazo[1,2-a]pyrazine-3-acetic acids has been prepared. A multi-step method similar to a synthetic procedure used to obtain Zolpidem, an imidazo[1,2-a]pyridine with hypnotic properties has been developed.
Untersuchungen an heterocyclischen Verbindungen, 35. Mitt. Synthese von 2-Phenylimidazo[1,2-a]pyrazin-3-acetaten
Zusammenfassung Angeregt durch die bemerkenswerte pharmakologische Aktivität der entsprechenden Carbonsäuren, wurde eine Reihe von 2-Phenylimidazo[1,2-a]pyrazin-3-acetaten synthetisiert. Zu diesem Zweck wurde eine mehrstufige Methode analog zu jener zur Herstellung von Zolpidem, einem Imidazo[1,2-a]pyridin mit hypnotischen Eigenschaften, entwickelt.相似文献
4.
Preparation of styryl derivatives of 2-phenyl-imidazo [1, 2-a]pyridine 2-(p-Tolyl)-imidazo [1, 2-a]pyridines and 7-methyl-2-phenyl-imidazo [1,2-a]-pyridines can be converted, in dimethylformamide, on reaction with anils of aromatic aldehydes in the presence of potassium hydroxide or potassium t-butoxide, into the corresponding 2-(stilben-4-yl)- and 2-phenyl-7-styry1-imidazo [1, 2-a]-pyridines (‘Anil-Synthesis’). The 2-(p-tolyl)-imidazo [1,2-a]pyridines react far less readily than the 7-methyl-2-phenyl-imidazo[1,2-a]pyridines. 相似文献
5.
V. I. Terenin E. A. Sumtsova E. V. Kabanova A. P. Pleshkova N. V. Zyk 《Chemistry of Heterocyclic Compounds》2004,40(4):436-445
Esters, nitriles, and amides of dipyrrolo[1,2-a:2',1'-c]pyrazines have been synthesized by the acylation of dipyrrolo[1,2-a:2',1'-c]pyrazines and 5,6-dihydrodipyrrolo[1,2-a:2',1'-c]pyrazines with trichloroacetic acid chloride, p-tosyl isocyanate, and isocyanatophosphoric acid dichloride (Kirsanov isocyanate). 相似文献
6.
Reactions of haloketenes with 2-arylideneaminopyridines were examined. Reaction of dichloroketene with 2-benzylideneaminopyridines gave 2,2-dichloro-3-phenyl-3-(2-pyridylamino)propanoic acids and 3-chloro-2-phenylpyrido[1,2-a]pyrimidin-4(4H)-ones. Similar reaction of dichloroketene with 2-(2-furfurylideneamino)-pyridines gave 3-chloro-2-(2-furyl)pyrido[1,2-a]pyrimidin-4-(4H)-ones. Chloroketene and chlorophenylketene also reacted with 2-arylideneaminopyridines to give pyrido[1,2-a]pyrimidin-4(4H)-ones. Ring transformations of pyrido[1,2-a]pyrimidin-4-(4H)-ones were carried out to give 1,8-naphthyridin-4(1H)-ones and imidazo[1,2-a]-pyridines. 相似文献
7.
The Compound 2-(N-Formyl-N-prop-2′-inyl)aminopyridine was cyclised in boiling formic acid to 3-methylimidazo[1,2-a]pyridine, with 3-methylene-2H-imidazo[1,2-a]pyridine as the intermediate. Under similar conditions the 1,3-diprop-2-inylpyrimido[4,5-b]quinoline-2,4-dione resulted from 1-methylimidazo[1,2-a]quinoline-4-carbonic acid-N-2-prop-2′-inylamide and from the 1-prop-2′-inylbenzo[b][1,8]naphthyridin-2-one the 1-methylbenzo[b]imidazo[1,2,3-ij]naphthyridine-4,7-dione as a new ring system, was obtained. 相似文献
8.
Branko Stanovnik Henry Van De Bovenkamp Jurij Svete Ale Hvala Igor Simoni
Miha Tiler 《Journal of heterocyclic chemistry》1990,27(2):359-361
Methyl 2-benzoylamino-3-dimethylaminopropenoate ( 2 ) was introduced as a new reagent for the preparation of fused pyrimidinones 4 from heterocyclic α-amino compounds in acetic acid. In this manner, derivatives of pyrido[1,2-a]pyrimidine 4a,b,f , pyrimido[1,2-b]pyridazine 4g , pyrimido[1,2-c]pyrimidine 4j , pyrazino[1,2-a]pyrimidine 4k , thiazolo[2,3-b]pyrimidine 41 , pyrazolo[1,5-a]pyrimidine 4m , and 1,2,4-triazolo-[1,5-a]pyrimidine 4n were prepared. 相似文献
9.
Transformations of methyl 3-dimethylamino-2-(1-methoxycarbonyl-4-oxo-4H-pyrido[1,2-a]pyrazin-3-yl)acrylate with some cyanomethylenecarbonyl group containing compounds or cyanamide into imidazo-[1,2-a]pyridines, irmdazo[1,2-a]pyrimidines and 2-oxa-6a, 10c-diazaaceanthrylenes are described. 相似文献
10.
The HeI photoelectron (PE) spectra of indole ( 1 ), benzimidazole ( 2 ), indazole ( 3 ), 3-chloro-indazole ( 4 ), imidazo[1,2-b]pyridazine ( 5 ), 6-chloroimidazo[1,2-b]pyridazine ( 6 ), 2-phenyl-imidazo[1,2-b]pyridazine ( 7 ), 2-phenyl-6-chloroimidazo[1,2-b]pyridazine ( 8 ), tetrazolo[1,2-a]-pyridine ( 9 ) and 8-cyanotetrazolo[1,5-a]pyridine ( 10 ) have been recorded. The spectra of 2–10 are of special interest for studying lone pair interactions. The assignment of the PE spectra submitted here, conjointly with the electronic structure of the studied compounds is discussed on the basis of molecular orbital calculations. 相似文献
11.
E. Abignente P. De Caprariis E. Fattorusso L. Mayol 《Journal of heterocyclic chemistry》1989,26(6):1875-1880
The reaction of various heteroarylamines with ethyl 2-benzoyl-2-bromoacetate was used to obtain some imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, imidazo[2,1-b]thiazoles and imidazo[2,1-b]benzothiazoles characterized by the presence of a phenyl moiety on the imidazole ring. In the case of thiazole and benzothiazole derivatives, unexpected by-products were isolated and their structures elucidated. 相似文献
12.
1,2-Diaminopyridinium iodide underwent reaction with ethyl acetoacetate to form 1,4-dihydro-2-methyl-4-oxopyrido[1,2-a]pyrimidin-1-ium iodide, and with acetyl acetone it gave 2,4-dimethylpyrido[1,2-a]pyrimidin-5-ium iodide. Though 2-acetylcyclohexanone gave the corresponding 5-methyl-1,2,3,4-tetrahydropyrido[1,2-a]quinazolin-11-ium iodide, no reaction was observed with 2,6-dimethyl-3,5-heptanedione, 1-benzoylacetone, 1,3-diphenyl-1,3-propanedione and its p-methoxyphenyl derivative. However, 1-aminopyridinium iodide and acetyl acetone in the presence of base gave 3-acetyl-2-methylpyrazolo[1,5-a]pyridine and 1-amino-2-methylpyridinium iodide yielded the corresponding 3-acetyl-2,7-dimethylpyrazolo[1,5-a]pyridine. With ethyl acetoacetate, the latter salt formed 3-ethoxycarbonyl-2,7-dimethylpyrazolo[1,5-a]pyridine but with 2,6-dimethyl substituents in the pyridine ring no condensation occurred. Reaction of 1-amino-2-methylpyridinium iodide with benzaldehyde gave N-benzalimino-2-methylpyridinium iodide which, on treatment with base, resulted in the formation of 2-picoline and benzonitrile, providing a convenient method of deamination. 相似文献
13.
Didier Legroux Jean-Paul Schoeni Christiane Pont Jean-Pierre Fleury 《Helvetica chimica acta》1987,70(1):187-195
2-Aza-1,3-dienes. Access to N-Aminoimidazoles, 3H-Pyrroles, [1,2,4]Triazolo[1,5-a]pyrazines, or Imidazo[1,2-a]pyrazines Nucleophilic attack of 5-(dialkylamino)-2-aza-1,3-diene-1,1-dicarbonitriles (or their 1-methoxycarbonyl analogous) by hydrazines or hydrazdes gives substituted N-aminoimidazoles, [1,2,4]triazolo-[1,5-a]pyrazines, or α-dihydrazino derivatives. With α-amino esters (or analogous), imidazo[1,2-a]pyrazines are produced. Addtion of cyanide anions occurs also with formation of substituted 3H-pyrroles. Structures and rationalisation of this nucleophilic attack are discussed. 相似文献
14.
Pier Luigi Ferrarini Claudio Mori Giampaolo Primofiore Lorella Calzolari 《Journal of heterocyclic chemistry》1990,27(4):881-886
The condensation of 2,6-diaminopyridine and 2-acetamido-6-aminopyridine with β-keto esters in polyphosphophoric acid was studied. In this reaction some 1,8-naphthyridinones, pyrido[1,2-a]pyrimidinones and pyrimido[1,2-a][1,8]naphthyridinones variously substituted were obtained. 相似文献
15.
Goryaeva M. V. Burgart Ya. V. Saloutin V. I. 《Russian Journal of Organic Chemistry》2010,46(3):432-438
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. 相似文献
16.
Istvn Hermecz Pter Forg Zsolt Bcskei Mikls Fehr Jzsef Kksi Gyrgy Szsz 《Journal of heterocyclic chemistry》1996,33(3):799-809
A series of 7,12-dihydropyrimido[1′2′:1,2]pyrido[3,4-b]mdole-4(6H)-ones was prepared by Fischer indolization of 9-arylhydrazono-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrirmdin-4-ones. Quantum chemical calculations (ab initio and AM1) indicate that position 3 of 7,12-dihydropyrimido[1′,2′:1,2]pyrido-[3,4-b]indole-4(6H)-one can be involved in electrophilic substitutions, while position 2 is sensitive towards nucleophilic attack. Bromination of 6-methyl-7,12-tetrahydropyrimido[1′,2′:1,2]pyrido-[3,4-b]indol-4(6H)-one 16 with bromine afforded 3-bromo derivative 25 , which was reacted with cyclic amines to give 2-ammo-7,12-dihydropyrirmdo[1′2′:1,2]pyrido[3,4-b]indol-4(6H)-ones 26–30 in an addition-elimination reaction. Vielsmeier-Haack formylation of compound 16 gave 12-formyl 31 and 3,12-diformyl 32 derivatives (an N-formyl-1-deaza derivative of nauclefidine alkaloid 34 ) at 60° and 100°, respectively. 3,12-Diformyl compound 32 was oxidized to 3-carboxyl derivative 33 with potassium permanganate. The quaternary salt 35 , obtained from compound 16 with dimethyl sulfate, suffered a ring opening on the action of aqueous sodium hydroxide. The new compounds have been characterized by elemental analyses uv, 1H nmr and in some cases by 13C ruler, CD spectra and X-ray investigations. 相似文献
17.
Silvio Massa Federico Corelli Giorgio Stefancich 《Journal of heterocyclic chemistry》1981,18(4):829-830
The reduction of 1-(2-methoxycarbonylphenyl)pyrrole-2-carboxaldehyde by lithium aluminum hydride led to 1-(2-hydroxymethylphenyl)-2-hydroxymethylpyrrole, which was in turn transformed into 4H,6H-pyrrolo-[1,2-a][4,1]benzoxazepine through intramolecular dehydration. The reductive action of sodium borohydride, instead, allowed the preparation of 6-oxo-4H-pyrrolo[1,2-a][4,1]benzoxazepine. 相似文献
18.
Ho Sik Kim Yoshihisa Kurasawa Chiemi Yoshii Minako Masuyama Atsushi Takada Yoshihisa Okamoto 《Journal of heterocyclic chemistry》1990,27(4):1115-1117
The reaction of the 2-substituted 6-chloroquinoxaline 4-oxides 1a or 1b with 2-fold molar amount of methyl propiolate resulted in the 1,3-dipolar cycloaddition reaction to give 8-chloro-1,3-bismethoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 4a or 8-chloro-1,3-bismethoxycarbonyl-4-(morpholin-4-yl)pyrrolo-[1,2-a]quinoxaline 4b , respectively. Compound 4a or 4b was transformed into 8-chloro-3-methoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 5a or 8-chloro-3-methoxycarbonyl-4-(morpholin-4-yl)pyrrolo[1,2-a]-quinoxaline 5b , respectively. The structure of 4a,b was confirmed by the NOE measurement among the C1 -H , C 2-H and C 9-H proton signals of 5a,b . An additional reaction mechanism was proposed for the ring transformation of isoxazolo[2,3-a]quinoxalines into pyrrolo[1,2-a]quinoxalines. 相似文献
19.
I. V. Ukrainets L. A. Grinevich A. A. Tkach O. V. Bevz S. V. Slobodzian 《Chemistry of Heterocyclic Compounds》2009,45(9):1058-1068
1-R-4-Hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid pyrazin-2-ylamides have been synthesized as potential antitubercular
agents. In contrast to pyrimidin-2-ylamides the compounds prepared are brominated by molecular bromine in glacial acetic acid
at position 6 of the quinolone ring rather than in the amide part of the molecule. The 1-N-allyl derivative behaves similarly
but undergoes halocyclization to give 2-bromomethyl-5-oxo-1,2-dihydro-5H-oxazolo[3,2-a]quinoline-4-carboxylic acid pyrazin-2-ylamide. A comparative analysis of the antimycobacterial properties of the synthesized
compounds and their isomeric pyrimidin-2-ylamides has been carried out. 相似文献
20.
By condensing alicyclic β-ketocarboxylates with substituted 2-aminopyridines in polyphosphoric acid or phosphoryl chloride-polyphosphoric acid, numerous 2,3-tri-, tetra-, penta- and hexamethylene-4H-pvrido[1,2-a]pyrimidin-4-ones were synthesized for pharmacological purposes. The stability and several reactions of the title compounds were studied. The 6-substituted-4H-pyrido[1,2-a]pyrimidin-4-ones were transformed into 1,8-naphthyridines in good yields independent of the ring size of ring C . The characteristic differences in the ir and uv spectra of the pyrido-pyrimidines and the corresponding naphthyridines are discussed. Catalytic hydrogenation of the pyrido[1,2-a]pyrimidin-4-ones furnished the corresponding 6,7,8,9-tetrahydropyrido-[1,2-a]pyrimidin-4-one derivatives. It was found that the A and C rings attached to the pyrirnidinone ring in solutions of unsubstituted tetrahydropyrido[1,2-a]pyrimidin-4-ones are flexible, whereas in the 6-methyl derivatives the conformer containing the 6-methyl group in axial position predominates. 相似文献