Synthesis of some new fused thiopyrano[2,3-d]thiazoles and their derivatives

A series of some new fused thiopyrano[2,3-d]thiazole derivatives have been synthesized by a stereo-selective hetero-Diels-Alder reaction of 5-(2,4-dihydroxy-benzylidene)-4-thioxo-thiazolidine derivatives 3a,b with acrylonitrile, ethyl acrylate, N-phenylmale-imide, ω-nitrostyrene and N-phenyl-1, 3, 4-triazole-2,5-dione. 5-Amino-9-hydroxy-dihydro-benzopyrano[3′,4′:4,5]thiopyrano[2,3-d]thiazol-6-one derivatives 14a,b have been synthesized by Michael addition of 3a,b with malononitrile. Structures and conceivable mechanisms are discussed.     

Pyridine-2(1H)-thione in heterocyclic synthesis: synthesis and antimicrobial activity of some new thio-substituted ethyl nicotinate,thieno[2,3-b]pyridine and pyridothienopyrimidine derivatives

3-(4-Bromophenyl)-2-cyanoprop-2-enethioamide (1) reacted with ethyl 3-oxo-3-phenylpropanoate (2) to give ethyl 4-(4-bromophenyl)-5-cyano-2-phenyl-6-thioxo-1,6-dihydropyridine-3-carboxylate (3). Compound 3 was taken as a starting material for the synthesis of thio-substituted ethyl nicotinate derivatives 5a–d, which underwent cyclization to the corresponding thieno[2,3-b]pyridines 6a–d. Also 3 reacted with hydrazine hydrate to give the pyrazolo[3,4-b]pyridine derivative 7, which upon diazotization gave the diazonium derivative 8. Compound 6a condensed with dimethylformamide–dimethylacetal to afford thieno[2,3-b]pyridine derivative 9, which reacted with different amines 10a–e to afford the pyridothienopyrimidine derivatives 12a–e through the Dimroth rearrangement. Moreover, compound 6a reacted with different reagents to give pyridothienopyrimidine derivatives 14a and b, 17 and pyrazolothienopyridine derivative 18. In addition, acetylating compound 6c with chloroacetylchloride afforded the 3-[(2)-chloroacetylamino]thieno[2,3-b]pyridine derivative 20, which upon cyclization yielded the corresponding 2-chloromethylpyrido[3′,2′:4,5]thieno[3,2-d]pyrimidine derivative 21. Some of the newly synthesized compounds were screened in vitro for their antimicrobial activities.

     

An efficient microwave-assisted synthesis of thieno[2,3- b ]quinolines under solvent-free conditions

A novel and efficient method for the synthesis of substituted thieno[2,3-b]quinolines has been developed. A simple one-pot reaction of 3-formyl-2-mercaptoquinolines 2a–l with 1-chloroacetone, 2-chloroacetamide, ethyl chloroacetate and 2-chloro-1-phenylethanone in presence of catalytic amount of potassium carbonate under microwave irradiation and solvent-free conditions gave thieno[2,3-b]quinolin-2-ylethanone derivatives 3a–e, thieno[2,3-b]quinoline-2-carboxamide derivatives 4a–e, ethyl thieno[2,3-b]quinoline-2-carboxylate 5a–e and phenyl(thieno[2,3-b]quinolin-2-yl)methanone derivatives 6a–e compounds respectively. The structures of all the newly synthesised compounds were elucidated on the basis of elemental analysis, IR, ¹H NMR and mass spectral data.     

Reaction of hydrazonoyl halides 49 1: Synthesis and antimicrobial activity of some new pyrimido[1,2-b][1,2,4,5]tetrazin-6-one,tetrazino[3,2-b]quinazolin-5-one,pyrimidino[1,2-b]1,2,4,5-tetrazin-5-one and triazolo[4,3-a]pyrimidine derivatives

Pyrimido[1,2-b][1,2,4,5]tetrazin-6-one, tetrazino[3,2-b]quinazolin-5-one, pyrimidino[1,2-b]1,2,4,5-tetrazin-5-one and triazolo[4,3-a]pyrimidine derivatives were synthesized from C-(4-methyl-2-phenyl)thiazol-5-oyl-N-phenyl-hydrazonoyl bromide and different pyrimidine-2-thiones. New compounds had their structures confirmed by elemental and spectral analysis and were screened antimicrobial activity.     

Synthese neuer Thieno [2′,3′; 4,5]imidazo[1,2-a]pyridiniumsalze

Syntheses of New Salts of Thieno[2′,3′;4,5]imidazo[1,2-a]pyridines Mesomeric 1-[2-amino-1-cyano-2-thio-]ethene-pyridinium ylides 1 are cyclizized to imidazo[1,2-a]pyridinium ylides 2 in the presence of HgO. S-alkylation of 2 leads to derivatives of 1-R¹-2-thio-3-cyano-imidazo[1,2-a]pyridinium halides 3 or 4 . Alkylation products from 2 with α-haloketones are cyclizized to thieno[2′,3′ 4,5]imidazo[1,2-a]pyridinium salts 5 .     

Synthesis,antimicrobial, anti-inflammatory and antioxidant activity of novel Spiro (imidazo[4′,5′:4,5′]benzo[1,2-e][1, 4] thiazepine)-9,3′-indolines

An efficient synthesis of novel spiro(imidazo[4′,5′:4,5′]benzo[1,2-e][1, 4]thiazepine)-9,3′-indolines has been accomplished from 5-amino-2-mercapto benzimidazole, istains and mercapto acetic acid. Compounds 6 were characterized by IR, ¹H NMR, ¹³C NMR and mass spectral data. The title compounds 6a–6e were evaluated for their antimicrobial, anti-inflammatory and antioxidant activity. Compounds 6a–6e exhibited significant antimicrobial activity, and as potent anti-inflammatory and antioxidant activities as that shown by standard drugs.     

Facile synthesis of novel 6-methyl-5-phenyl-2-sulfido-1,2,3,5-tetrahydro-4H[1,2] oxazolo[4′,5′:5,6]pyrano[2,3-d][1,3,2]diazaphosphinines

A number of 6-methyl-5-phenyl-2-sulfido-1,2,3,5-tetrahydro-4H[1,2]oxazolo[4′,5′: 5,6]pyrano[2,3-d][1,3,2]diazaphosphinines 4–11 were synthesized via an interaction of tetraphosphorus decasulfide and Lawesson’s reagent under different conditions with 6-amino-3-methyl-4-phenyl-4H-pyrano[3,2-d][1,2]oxazole-5-carbonitrile (3). The reaction mechanisms for these products were discussed. Structures of the newly synthesized products were established on the basis of elemental analysis and spectral data.     

Pyrido[2,3-d]pyrimidine-2,7-dithiol in heterocyclic synthesis: Synthesis and characterization of several new fused pyridopyrimidine heterocycles

Pyridine-2(1H)-thione 1 reacted with phenyl isothiocyanate to give pyrido[2,3-d]pyrimidine derivative 3. Compound 3 reacted with halogen containing compounds 4a–d and methyl iodide in dimethylformamide/potassium hydroxide solution at room temperature to give 2,7-bisalkylthiopyrido[2,3-b]pyrimidine derivatives 5a–d and 9, respectively. Compounds 5a–d could be cyclized into thienopyrido[2,3-d]pyrimidine derivatives 6a–d by boiling with ethanolic potassium hydroxide solution. Compound 6a reacted with acetic anhydride or formic acid and gave the corresponding pyrimido[4″,5″:4′,5′]thieno[3′,2′:5,6]pyrido[2,3-d]pyrimidine derivatives 8a,b. Compound 9 reacted with hydrazine hydrate to yield pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine derivative 11 which could be reacted with nitrous acid and dimethylformamide-dimethylacetal (DMF-DMA) and gave the final isolable products corresponding to the pyrazolo[4′,3′:5,6]pyrido[2,3-d]tetrazolo-[5,1-b]pyrimidine and pyrimido[1″,2″:1′,5′]pyrazolo[4′,3′:5,6]pyrido[2,3-d]1 Abbas, A. A., Elneairy, M. A.A. and Mabkhot, Y. N. 2001. J. Chem. Res.(S), 4: 124[Crossref] , [Google Scholar] 2 Riad, B. Y., Negem, A. M., Abdou, S. E. and Daboun, H. A. 1987. Heterocycles, 26: 205[Crossref], [Web of Science ®] , [Google Scholar] 4 Gad-Elkareem, M. A.M. and Abedelhamid, A. O. 2004. Afinidad, 61(513): 427[Web of Science ®] , [Google Scholar]triazolo-[4,3-b] pyrimidine derivatives 13 and 17, respectively. Compound 11 also reacted with some β-dicarbonyl compounds such as acetylacetone (18) and ethyl acetoacetate (20) to yield the corresponding pyrimido[1″,2″:1′,5′]pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine derivatives 19 and 21, respectively. Finally, compound 11 reacted with chloroacetyl chloride (22) to give the corresponding imidazo[1″′,2″′:1″,5″]pyrazolo[4″,3″:5′,6′]pyrido[3′,2′:5,6]pyrimido[2,1-c]1 Abbas, A. A., Elneairy, M. A.A. and Mabkhot, Y. N. 2001. J. Chem. Res.(S), 4: 124[Crossref] , [Google Scholar] 2 Riad, B. Y., Negem, A. M., Abdou, S. E. and Daboun, H. A. 1987. Heterocycles, 26: 205[Crossref], [Web of Science ®] , [Google Scholar] 4 Gad-Elkareem, M. A.M. and Abedelhamid, A. O. 2004. Afinidad, 61(513): 427[Web of Science ®] , [Google Scholar]triazine derivative 23.     

Attempted Synthesis of Bowl-Shaped Polycyclic Aromatic Hydrocarbons via Oxidative Electrocyclization. Products from the Dications of Dibenzo [g,p] chrysene,Tetrabenzo[5.5]fulvalene,and Diphenylmethylidenefluorene

Synthesis of diindeno[1,2,3,4-defg: 1′,2′,3′,4′-mnop]chrysene (1), a portion of the C₆₀ surface, was attempted through oxidative cyclization of tetrabenzo[5.5]fulvalene (2), dibenzo[gp]chrysene (3), and diphenylmethylidenefluorene (4) by SbF₅/SO₂CIF. Compounds 2 and 3 were oxidized to dications which then underwent a single cyclization to give precursors to 1. Compound 4 underwent two oxidative cyclizations to give a precursor to 1. AM1 calculations of the possible products from cyclization were consistent with preferential formation of the cyclized product with the lower ΔHf. Oxidative cyclization may offer a one-pot synthetic alternative for the preparation of unusual polycyclic aromatic hydrocarbons.     

2-Mercapto-4,6-disubstituted nicotinonitriles: versatile precursors for novel mono- and bis[thienopyridines]

A series of novel thieno[2,3-b]pyridines were prepared from the reaction of the appropriate bromoacetylbenzofurans or bromoacetylbenzothiazole with the corresponding pyridinethione derivatives in ethanolic sodium ethoxide at reflux. Moreover, new bis(thieno[2,3-b]pyridine) derivatives have also been synthesized by the reaction of the appropriate bis-bromoacetyl derivatives with the corresponding pyridinethiones in the presence of sodium ethoxide. Attempts to synthesize the target bis(thieno[2,3-b]pyridine) derivatives by bis-alkylation of the corresponding (thieno[2,3-b]pyridin-2-yl)(hydroxyphenyl)methanone with the appropriate dihaloalkanes using a mild base were unsuccessful.     

Regioselective synthesis of new 5-methyl-5H-pyrimido[4′,5′:4,5][1,3]thiazino [3,2-a]perimidines

A convenient and efficient regioselective synthesis of new pyrimido[4′,5′:4,5] [1,3]thiazino[3,2-a]perimidines is described through intermolecular heterocyclization of 2,4-dichloro-5-(chloromethyl)-6-methylpyrimidine and 1H-perimidine-2(3H)-thione in short reaction times under mild conditions.     

Design,synthesis, and antimicrobial activity of novel spiroisoxazolo[2,3-b][1,2,4]thiadiazole-2,2′-thiazolidine- 4′-ones and spiroisoxazolo[2,3-b][1,2,4]oxadiazole-2, 2′-thiazolidine-4′-ones

A new synthetic strategy for the synthesis of novel 6-methyl-3′-aryl spiro[isoxazolo[2,3-b][1,2,4]thiadiazole-2,2′-thiazolidin]-4′-ones (9a–9e) and 6-methyl-3′-aryl spiro[isoxazolo[2,3-b][1,2,4]oxadiazole- 2,2′-thiazolidin]-4′-ones (12a–12e) analogs is described. These compounds showed significant antimicrobial activity against all the standard strains.     

A convenient [hydroxy(tosyloxy)iodo]benzene-mediated one-pot synthesis of 2-arylimidazo[2,1-b]benzothiazoles

Several 2-arylimidazo[2,1-b]benzothiazoles (4) have been conveniently synthesized in one-pot reactions via α-tosyloxylation of enolizable ketones (1) using [hydroxy(tosyloxy)iodo]benzene 2 in acetonitrile, followed by treatment with 2-amino-6-(substituted)benzothiazoles (3). The present protocol offers several advantages towards general access of 2-arylimidazo[2,1-b]benzothiazoles, including an intriguing alternative to the literature protocols, a readily available nontoxic reagent, operational simplicity and an environmentally benign procedure.     

Regioselective synthesis of new 5H,10H-dipyrimido[2,1-b:4′,5′-d][1,3]thiazine: a combined experimental and computational study

Several derivatives of the novel tricyclic system ‘dipyrimido[2,1-b:4′,5′-d][1,3]thiazine’ were synthesized via inter- and intramolecular heterocyclization of 2,4-dichloro-5-(chloromethyl)-6-methylpyrimidine and 6-amino-4-aryl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile in short reaction times under mild conditions. An x-ray analysis together with computational calculations was performed to gain an in-depth understanding of regioselectivity of the reaction.     

Reaction of ethyl N-(6-ethoxycarbonyl-2-methylthiothieno[2,3-d]-pyrimidin-5-yl) formimidate with alkyl- and arylhydrazines: Formation of modified thieno[2,3-d]pyrimidines and thieno[2,3-d:4,5-d]dipyrimidin-4-ones

The reaction of ethyl N-(6-ethoxycarbonyl-2-methyl-thiothieno[2,3-d]pyrimidin-5-yl)formimidate ( 1 ) with methyl-hydrazine, N,N′-dimethyl- and N,N′-diphenylhydrazines separately in refluxing ethanol resulted in hydrolysis of formimidate group to give ethyl 5-amino-2-methylthiothieno[2,3-d] pyrimidine-6-carboxylate ( 2 ). The reaction on 1 with methyl-hydrazine without solvent afforded ethyl 5-amino-2-(1-methyl-hydrazino)thieno[2,3-d]pyrimidine-6-carboxylate ( 3 ), which underwent hydrazone formation with p-nitrobenzaldehyde to give 4 . Treatment of 1 with N,N-dimethylhydrazine afforded a mixture of 3-dimethylamino-7-methylthiothieno[2,3-d:4,5-d']dipyrimidin-4(3H)-one ( 5 ) and 2 . Displacement of methylthio group in 5 with morpholine, piperidine and 4-methylpiperazine gave the corresponding 7-substituted derivatives 6a-c . The reaction of 1 with para-substituted phenylhydrazines resulted in the formation of 3-(p-substituted phenylamino)7-methylthiothieno[2,3-d:4,5-d']dipyrimidin-4 (3H)ones ( 7a-c ).     

Photooxygenation of the Condensation Products of Naphthanthrone

The structure of the polycyclic aromatic hydrocarbon with the absorption maximum at 567 nm, synthesized by the condensation of naphth- anthrone (NT), was deduced to be benzo[rs]dinaphtho[2, 1, 8, 7-klmn:2, 3, 4, 5, 6-vwxyz]hexaphene (BDH) by semi-empirical molecular orbital calculation methods. The photooxygenation of BDH and benzo[op]naphtho[2, 1, 8, 7-hijk]anthra[2, 1, 9, 8-stuva]-pentacene (BNAP) due to irradiate to light with each absorption maximum was investigated by measurering the absorption spectra and applying semi-empirical molecular orbital calculation methods. BNAP is synthesized by the same reaction process together with dibenzo[de:op]dinaphtho[2, 1, 8, 7-hijk : 2′, 1′, 8′, 7′-syuv]pentacene (DDP). BNAP and BDH do not undergo photooxygenation. On the other hand, DDP undergoes photooxygenation. The empirical results were illustrated in terms of difference in heat of reaction, which were 25.5 and 30.2 kJ/mol for BDH and BNAP, respectively. Their values are considerably larger than -3.1 kJ/mol of DDP. The difference in heat of formation seems to be the reason why BDH and BNAP does not undergo photooxygenation.     

One-Pot Synthesis of Spiro[chromeno[2,3-c]pyrazole-4,3′-indoline]-diones Using Sulfonic Acid Functionalized Nanoporous Silica SBA-Pr-SO3H and Study of Their Antimicrobial Properties

A novel and clean one-pot synthesis of spiro[chromeno[2,3-c]pyrazole-4,3′-indoline]-2′,5(6H)-diones via cyclocondensation reaction of isatins, 1,3-cyclohexadiones, and pyrazolone in aqueous media using SBA-Pr-SO₃H (sulfonic acid-functionalized mesoporous silica) as an efficient heterogeneous solid acid catalyst was reported. The antimicrobial activities of synthesized compounds have been tested.     

An efficient one-pot protocol for regioselective synthesis of 3-aryl-6,8-dialkyl-7-thioxo-7,8-dihydropyrimido[4,5-c] pyridazine-5(6H)-ones

A series of 3-aryl-6,8-dialkyl-7-thioxo-7,8-dihydropyrimido[4,5-c]pyridazine-5(6H)-one derivatives have been regioselectively synthesized via the one-pot three-component reaction of 1,3-dimethylthiobarbituric acid and 1,3-diethylthiobarbituric acid with various arylglyoxals in the presence of hydrazinium dihydrochloride in warm ethanol. These new substituted pyrimidopyridazines may be potential monoamine oxidase inhibitors.     

Synthesis,Thermal Stability and Impact Stability of Novel Tetranitro‐Dipyridotetraazapentalene Derivatives

The synthetic details for the construction of three new dipyridotetraazapentalene derivatives, 5H‐pyrido[3″,4″:4′,5′] [1,2,3]triazolo‐ [1′,2′:1,2][1,2,3]triazolo[5,4‐b]pyridin‐6‐ium inner salt ( 8 ), 5H‐pyrido[3″,2″:4′,5′] [1,2,3]triazolo[1′,2′:1,2] [1,2,3]triazolo[5,4‐b]‐pyridin‐6‐ium inner salt ( 15 ) and 5H‐pyrido[2″,3″:4′,5′] [1,2,3]‐triazolo[1′,2′:1,2][1,2,3]triazolo[4,5‐b]pyridin‐6‐ium inner salt ( 16 ) are presented. Nitration of ( 8 ) and ( 15 ) afforded the novel tetranitrodipyridotetraazapentalene derivatives, 2,4,8,10‐tetranitro‐5H‐pyrido[3″,4″:4′,5′][1,2,3]triazolo[1′,2′:1,2][1,2,3]‐triazolo[5,4‐b]‐pyridin‐6‐ium inner salt ( 3 ) and 2,4,8,10‐tetranitro‐5H‐pyrido[3″,2″:4′,5′][1,2,3]triazolo[1′,2′:1,2][1,2,3]‐triazolo[5,4‐b]‐pyridin‐6‐ium inner salt ( 4 ) in good yields. Both isomers, ( 3 ) and ( 4 ), exhibited high thermal stability (differential scanning calorimetric analysis and thermal gravimetric analysis) and were insensitive to impact (hammer/anvil test).     

A facile synthesis of some novel fused [1,2,4]triazolo[3,4-b][1,3,4]thiadiazol derivatives

A series of novel 3-[6-(4-substituted phenyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-3-ylmethyl]-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidin-4(3H)-one derivatives (7a–7h) have been synthesized from 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitrile (1) through a multi-step reaction sequence. The key intermediate (6) on condensation with various substituted aromatic carboxylic acids in the presence of phosphorus oxychloride afforded the series of title compounds (7a–7h). The structures of all newly synthesized compounds were established on the basis of their IR, ¹H-NMR, ¹³C-NMR and liquid chromatography mass spectrometry spectral data.