Interaction of (z)-4-bromo-1,3-di(2-thienyl)- 2-buten-1-one with amines, synthesis of di(2-thienyl)azolo[a]pyridines (original) (raw)
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European Journal of Chemistry, 2011
Journal of Chemistry, 2013
Condensation of sodium 3-oxo-3-(1-phenyl-1H-pyrazol-4-yl)prop-1-en-1-olate (2) with several heterocyclic amines, cyanoacetamide, cyanothioacetamide, and 2-cyanoacetohydrazide gives pyrazolo[1,5-a]pyrimidines (5a-d), pyrido[2 ,3 :3,4]pyrazolo[1,5a]pyrimidine (9), benzo imidazo[1,2-a]pyrimidine (10), [1,2,4]triazolo[1,5-a]pyrimidine (11), and pyridine derivatives (12-14). Also, thieno[2,3-b]pyridines (15-18) were synthesized via pyridinethione (13) with -halo ketones and -halo ester. Structures of the newly synthesized compounds were elucidated by elemental analysis, spectral data, alternative synthetic routes, and chemical transformation whenever possible.
HETEROCYCLES, 2000
Substituted 3-amino-4-oxo-4H-pyridino[1,2-α]pyrimidines (6, 7), available in 2 steps from methyl 2-benzyloxycarbonylamino-3-dimethylaminopropenoate (3) and 2-aminopyridines (1, 2), were diazotized into stable diazonium tetrafluoroborates (8, 9). Heating of diazonium salts (8, 9) with primary alcohols furnished alkyl 1-(substituted pyridin-2-yl)-1H-1,2,3-triazoles (11, 12) in 30-70% yields. Quinolizines 1 and their 1-aza analogs, pyridino[1,2-α]pyimidines, 2 are constituents of various naturally occurring alkaloids exhibiting neuroleptic 3 analgesic, 4 antiemetic, 5 antibacterial, 6 and antitumor activity. 7 On the other hand, 1,2,3-triazoles and fused 1,2,3-triazoles also represent an important class of heterocyclic compounds which have found a wide and versatile use in organic synthesis, medicinal chemistry, and industrial applications. 8 For example, 1H-1,2,3-benzotriazole is a highly efficient synthetic auxiliary 9 and numerous 1,2,3-triazole derivatives exhibit diverse biological activities, such as antiviral, 10 fungicidal, 11 muscarinic, 12 antiallergic, 13 anticoccidial, 14 anti-HIV-1, 15 antiepileptic, 16 antiinflammatory, 17 prostaglandin synthesis inhibition, 18 and others. 19 Recently, 2-substituted 3-(dimethylamino)propenoates proved to be simple and efficient reagents for the preparation of various heterocyclic systems. 20,21 For example, 3-substituted 4-oxo-4H-pyridino[1,2-]pyrimidines can be prepared in one step from 2-aminopyridines and 2-substituted 3-(dimethylamino)propenoates. 20-23 Utilization of 2-benzyloxycarbonylamino and 2-vinylamino substituted 3-(dimethylamino)propenoates made 3-amino-4-oxo-4H-pyridino[1,2-]pyrimidines available in two steps and good yields from 2-aminopyridine derivatives. 22,23 In continuation of our research in this field we studied transformations of 3-amino-4-oxo-4H-pyridino[1,2
Synthesis of (pyridinyl)-1,2,4-triazolo[4,3-a]pyridines
Journal of Heterocyclic Chemistry, 1986
Methods for the synthesis of (pyridinyl)1,2,4-triazolo[4,3-u]pyridines were developed. The principal route to the required intermediate 2-chloropyridines was based on rearrangements of mono N-oxides of 2,2'-bipyridine, 2,3'-bipyridine, 3,3'-bipyridine, 2,4'-bipyridine and 4,4'-bipyridine with phosphorus oxychloride. Reaction of 3,3'-bipyridine I-oxide or 2,2'-bipyridine 1-oxide with phosphorus oxychloride gave mixtures of chloro isomers. Reaction with acetic anhydride, 3,3'-bipyridine 1-oxide and 2,2'-bipyridine I-oxide gave exclusively [3,3'-bipyridine]-2(l m o n e and [2,2'-bipyridine]-6(1H)-one, respectively. 1,2,4-Triazolo[4,3-a]pyridines with pyridinyl groups at the 5,6,7 and 8 positions were synthesized.
2015
The synthetic chemistry has gained much attention because of the broad spectrum of biological activities related to structural features of various synthesized molecules. The synthetic chemistry has prominent application in the field of pharmaceutical or medicinal chemistry regarding new drug candidates. In this regard, the three concerned functionalities; 1,3,4-oxadiazole, azomethine and benzo-2-pyrone; have gained much attention because of their notable biological activities. The current research work was an effort to synthesize different molecules bearing these functionalities; 1,3,4-oxadiazole derivatives bearing azomethine functio nality and benzo-2-pyrone derivatives bearing acetamide functionality; and to evaluate their antibacterial and enzyme inhibition potential. Eight (8) different carboxylic acids (I 1-8) were employed to synthesize one hundred thirty three (133) azomethine compounds (VIII 1-133 , Scheme-1) by converting them to corresponding ethyl esters (II 1-8) by ethanol on reflux, carbohydrazides (III 1-8) by hydrazine on stirring at RT (room temperature) or reflux, 1,3,4-oxadiazoles (IV 1-8) by carbon disulfide on reflux, ethyl esters (V 1-8) by ethyl 2bromoethanoate (EBE) on stirring at RT, again carbohydrazides (VI 1-8) with hydrazine on stirring at RT and finally azomethine derivatives (VIII 1-133) with aryl carboxaldehydes (VII 1-19) on stirring at RT. 2,4-Dimethylphenol (IX) was also converted to thirteen (13) compounds (XV 1-13 , Scheme-2) of such type through the same steps except first one for the synthesis of ethyl ester (X) by ethyl 2bromoethanoate (EBE) on reflux. 4-Chloro-1,3-dihydroxybenzene (XVI) was converted to heterocyclic 6chloro-7-hydroxy-4-methylbenzo-2-pyrone (coumarin, XVII) by reaction with ethyl 2-ethanoylethanoate (EEE) in concentrated sulfuric acid. The synthesized benzo-2pyrone molecule was O-substituted by alkyl halides (XVIII 1-9) to synthesize XIX 1-9 and by acyl halides (XX 1-8) to synthesize XXI 1-8 (Scheme-3). The different alkyl/aralkyl/aryl amines (XXII 1-27) were made to react with 2-bromoethanoyl bromide (BEB) on stirring to synthesize a number of new electrophiles (XXIII 1-27 , Scheme-4). These synthesized electrophiles were subjected to react with XVII to synthesize N-substituted acetamide derivatives (XXIV 1-26 , Scheme-5) and then with 4-hydroxybenzo-2-pyrone (XXV) to synthesize XXVI 1-18 (Scheme-6) on stirring at RT. The N-substituted 1,3,4-oxadiazole acetamide derivatives (XXX 1-27 , Scheme-7) of benzo-2-pyrone were synthesized by stirring XXIII 1-27 with 5-{[(6-chloro-4-IX methylbenzo-2-pyron-7-yl)oxy]methyl}-1,3,4-oxadiazol-2-thiol (XXIX), prepared by the same steps as that for 5-[(2,4-Dimethylphenoxy)methyl]-1,3,4-oxadiazol-2-thiol (XII) in Scheme-2. All the proposed structures of synthesized compounds were characterized by IR (Infra Red), PNMR (Proton Nuclear Magnetic Resonance) and EIMS (Electron Impact Mass Spectrometry) spectral data. Ring formation of 1,3,4-oxadiazole and benzo-2-pyrone was confirmed through CNMR (Carbon-13 Nuclear Magnetic Resonance). The compounds have been enriched by their physical data also. All the synthesized compounds were screened against two Gram-positive and three Gramnegative bacteria to evaluate their antibacterial potential with reference of Ciprofloxacin, the reference drug. Along with antibacterial potential, these were also evaluated for their LOX (Lipoxygenase) inhibition potential with reference to Baicalein. Among the 1,3,4-oxadiazole bearing azomethine compounds (Scheme-1 and Scheme-2), VIII 5,7,48,53 & XV 1,8-10 , were the most active against both of the Grampositive bacterial strains and the compounds, VIII 5,53,90,124 , were the most active against all the three Gram-negative bacterial strains. Also against all the five bacterial strains, VIII 5,53 , were the best inhibitors. Against LOX, the compound, XV 9 bearing 5-[(2,4-Dimethylphenoxy)methyl]-1,3,4-oxadiazol-2-yl and 3-nitrobenzylidene, was better inhibitor even than Baicalein, as evident from its four times low IC 50 value. Among the benzo-2-pyrone derivatives (Scheme-3 to Scheme-7), the compounds obtained after alkylation (XIX 1-9) of benzo-2-pyrone were relatively more efficient against the bacterial strains taken into account than the acylated (XXI 1-8) ones. The compounds, XIX 1,2,8,9 , were the active inhibitors of all the bacterial strains. The acetamidic compounds, XXIV 4,15,23,26 presented notably valuable inhibitory potential for all the bacterial strains. The LOX inhibition potential was too much low for these compounds. All the compounds, XXVI 1-18 , were notably active against all the strains but two compounds, XXVI 16,17 , were the most efficient ones. Among the compounds, XXX 1-27 , the Gram-negative strains were efficiently inhibited than Grampositive ones. The best activity was presented by XXX 5,6,10,22. Among the acetamidic 1,3,4-oxadiazole compounds, the molecules bearing alkyl substituted phenyl rings and aralkyl groups with long aliphatic chain resulted in moderate to good activity. The molecules bearing ortho substituted phenyl rings remained active against all the strains, also good to excellent and more efficient against the Gram negative strains. The meta substituted phenyl rings were also good against negative strains but the para R = Different substituents, R 1 = Aryl groups, R 2 = Alkyl/aralkyl groups, R 3 = Alkyl/aryl groups, R 4 = Alkyl/aralkyl/aryl groups, n = 1 or 0. XII
ChemInform, 2005
Reaction of 2-acetylbenzoimidazole 1 with some arylaldehydes under different conditions gave chalcones, 1,5-pentanediones and pyridines. Treatment of chalcones with various types of reagents gave the corresponding new pyridines, thienopyridines, pyrido[2,3:4',5']thieno[3',2'-d]pyrimidin-8-ones via initial addition of active methylene or amino group to the double bond followed by cyclization.