SYNTHESIS OF BENZO[1,2-b: 5,4-b′]- DIFURANYL-TRIAZOLES, -OXADIAZOLES, -THIAZOLIDINONES, -THIADIAZOLES,AND THE USE OF DNA IN EVALUATION OF THEIR BIOLOGICAL ACTIVITY

Benzo[1,2-b:5,4-b′]difuran-2-carbohydrazides 5a, b were reacted with aryl or alkyl isothiocyanates to give the corresponding thiosemicarbazides 6a–h. Cyclization of the substituted thiosemicarbazides with sodium hydroxide led to the formation of benzo[1,2-b:5,4-b′]difuranyl-1,3,4-triazoles 7a–f. Desulfurization of thiosemicarbazides by mercuric oxide gave benzo[1,2-b:5,4-b′]difuranyl-1,3,4-oxadiazoles 8a–f. Treatment of thiosemicarbazides with ethyl bromoacetate or α-bromopropionic acid yielded benzo[1,2-b:5,4-b′]difuranyl-carbonyl-hydrazono-4-thiazolidinones 9a–f and 10a–f, respectively. Furthermore, the reaction of the thiosemicarbazides with phosphorus oxychloride gave benzo[1,2-b:5,4-b′]difuranyl-1,3,4-thiadiazoles 11a–f. Some compounds in this study were biologically evaluated for their ability to bind to DNA.     

Synthesis and biological assessment of novel cyanopyridine derivatives

New pyridine derivatives bearing p-dimethyl amino phenyl and p-bromophenyl moieties at position-4 and 6 have been prepared. The behavior of pyridone derivative 2 toward ethyl chloroacetate followed by hydrazine hydrate gave pyridinyl acetohydrazide derivative 7, and its behavior toward carbon electrophiles has been investigated by its reaction with aromatic aldehydes, ethyl acetoacetate, acetyl acetone, cyclohexanone, phthalic anhydride, maleic anhydride, and isatin affording the pyridine derivatives 8a–e to 16, respectively. Treatment of compound 2 with acrylonitrile in Et₃N, yielded the N- alkylated derivative 17. Some pyrazole derivatives have been synthesized by interaction of the chalcone 1 with hydrazine hydrate afforded pyrazole derivative 18. Treatment of compound 18 with benzoyl chloride and or acetic anhydride resulted in the formation of the acylated compounds 19 and 20. Elemental and spectroscopic pieces of evidence characterized all the newly synthesized compounds. Some of the synthesized compounds were tested for their antibacterial activities against Gram-positive and Gram-negative bacteria.     

Novel Syntheses and Reactions of Polynuclear Heterocyclic Derivatives Derived From Thioxopyridopyrimidine,With a New Ring System

Pyridopyrimidine derivatives 2 reacted with hydrazonoylchloride derivatives and yielded triazolopyridopyrimidines 6a–f. Compound 4b reacted with aliphatic acids and afforded triazolo-pyridopyrimidines 7a,b, and the reaction with carbon disulfide afforded 10-mercapto-triazolopyridopyrimidine (10). Moreover, the reaction of 4b with β -ketoesters afforded 10-pyrazolyl-pyridopyrimidines derivatives 11, 13, 14, and 15. Compound 4b reacted with nitrous acid to give tetrazolopyridopyrimidine 16, which reduced to 10-amino-derivative 17. On the other hand, the reaction of 4b with aromatic aldehydes afforded arylidines derivatives 18a–c, which were later cyclized to triazolo-pyridopyrimidines deivatives 19a–c. Finally, 4b reacted with α-haloketones to give triazines derivativrs 20, with new ring systems.     

SYNTHESIS OF POLYFUSED THIENO(2,3-b)THIOPHENES PART 1: SYNTHESIS OF THIENOPYRIMIDINE DERIVATIVES

Abstract

3,4-Diamino-2,5-dicarbethoxythieno(2.3-b)thiophene 1 reacted with malononitrile or ethyl cyanoacetate to afford bis(thienopyrimidin-4-one) derivatives 2_a.b The reaction of compound 1 with o-aminothiophenol, o-aminophenol or o-phenylenediamine gave benzothiazolyl-, benzoxazolyl-, benzoimidazolylthienothiophene 3_a-c, Chloroacetylation of compound 1 and reacting the resulting compound 4 with malononitrile furnished thienopyrolopyrimidine 6. Fusion of compound 1 with formamide yielded bis(thienopyrimidine) 7 which reacted with POCI₃/PCl₅ to yield the corresponding chloro derivative 8 which was converted into the corresponding hydrazine derivative 9. Treatment of compound 1 with CS₂, NaOH and 1,2 dibromoethane produced the corresponding 1.3 dithiolane 11 which also treated with chloroacetyl chloride or ethyl mercaptoacetate to get the corresponding β-lactame 12 or thiazolidinone 13. On reacting compound 1 with CS₂, NaOH and (CH₃)₂S0₄ produced the corresponding bi(dithiocarbamate methyl ester) 14 which treated with hydrazine hydrate to yield the corresponding bis(thienopyrimidine) derivative 15. This compound reacted with Lawesson's reagent (LR) to give the desired compounds 16 and 17. While its reaction with (CH₃)₂ SO₄ and NaOH furnished the corresponding methyl derivative 18. Fusion of compound 18 with aniline afforded compound 19. Compound 19 was allowed to react with ethyl acetoacetate, acetylacetone, α-oxoketene dithioacetal, ethoxymethylene malononitrile or LR to get the described compounds 2O_a.b-24 respectively.     

SYNTHESIS OF SOME NEW 3-ARYLOXYMETHYL- 4-PHENYL-5-(N-SUBSTITUTED CARBOXAMIDOMETHYLTHI0)-S-TRIAZOLES

Abstract

3-Aryloxymethyl-4-phenyl-5-mercapto-s-triazoles (I_a-c) have been synthesized and reacted with N-chloroacetyl derivatives of aromatic and/or heterocyclic amines to yield 5-(N-aryl/heterocyclyl)-carboxamidomethyl thio-s-triazole derivatives 2_a-o and 3_a-o respectively. Reaction of I_a-u with ethyl chloroacetate gave the corresponding esters 4_a-c which were reacted with hydrazine hydrate to give hydrazides 5_a-c. Condensation of 5_a-c with aromatic aldehydes gave Schiff s bases 6_a-u with on cycloaddition reaction with thioglycolic acid yielded 4-thiazolidinones 7_a-g. Some of these compounds were screened in vitro for their antibacterial activities.     

New N,S-Substituted Dienes from Mono(thio)substituted-2-nitrohalo-1,3-diene and Some Amines

Mono(thio)substituted nitrodiene compound 1 reacted with 2a–f and yielded 3a–f in methylene chloride. Compound 1 gave 7 by the reaction with 6. Compounds 5a–c were obtained by the reactions of 4a–c with 1. 3a also has been structurally characterized using single-crystal X-ray diffraction analyses.     

Pyridazine Derivatives and Related Compounds,Part 17: 1 The Synthesis of Some 3-Substituted Pyridazino[3′, 4′:3, 4]pyrazolo[5, 1-c]-1,2,4-triazines and Their Antimicrobial Activity

The reaction of the hydrazide of pyridazino[3′, 4′:3, 4]pyrazolo[5, 1-c]-1,2,4-triazine-3-carboxylic acid 3 with carbon disulfide in the presence of potassium hydroxide gave the 1,3,4-oxadiazole-2-thione derivative 4. The methylation of this product in an alkaline medium proceeds at the sulfur atom. The reaction of 3 with KOH and carbon disulfide followed by addition of hydrazine hydrate afforded the 4-amino-1,2,4-triazole derivative 6. Compound 3, when heated either with ammonium thiocyanate or with potassium thiocyanate, afforded the same product 7, which underwent cyclodehydration in the presence of acetyl chloride, which led to the 2-acetylamino-1,3,4-thiadiazole derivative 8. In a basic medium, the product was 1,2,4-triazole-3-thione derivative 9. The reaction of 3 with phenyl isothiocyanate provided thiosemicarbazide derivative 10, which underwent cyclodehydration in a basic medium and gave the 1,2,4-triazole derivative 11. The reaction of 3 with formic acid yielded the 3-carboxyl-2′-(formyl)hydrazine derivative 12. The refluxing of the latter with phosphorus pentasulfide in xylene yielded compound 14 (65%). The reaction of compound 12 with phosphorus pentoxide afforded compound 15. Some representative examples were screened for antimicrobial activity.     

Facile Syntheses of Some Thieno[2,3-d] Pyrimidine Derivatives

In one-pot synthesis 2-arylidene-5,6,7,8-tetrahydrothiazolo[3,2-a] cyclopenteno-thieno[2,3-d] pyrimidine-3,5-diones (3) were prepared via the reaction of a ternary mixture of 2-thioxo-1,3,4,5,6,7-hexahydr cyclopentinothieno [2,3-d]-4-one (2), chloroacetic acid and a proper aldehyde. Compound 2 reacted with 3-chloropent-2, 4-dione in ethanolic potassium hydroxide yielding the S-acetyl acetone derivative 5f . The latter compound reacted with hydrazine hydrate and phenyl hydrazine yielded the 2-pyrazolthio derivative 10a, b. Compound 5f also underwent cyclization on heating with acetic acid—pyridine solution to give 11. The 2-methylthio derivative 5a, when treated with hydrogen peroxide gave the corresponding oxidized product 9.     

Studies of Thiazolopyridines,Part 6: Synthesis and Antimicrobial Evaluation of Some Novel Thiazolo[3,2-a] Pyridine and Thiazolo[2′,3′:6,1]-pyrido[2,3-d]pyrimidine Derivatives

Condensation of thiazolinone 1 with aromatic aldehydes yielded the corresponding methylidene derivatives 2a–f. Cyclization of compounds 2a–f with arylidenemalononitrile 3 (1:1 molar ratio) in ethanol in the presence of piperidine furnished the novel thiazolo[3,2-a]pyridines 5a–v, via Michael adduct 4. Compounds 5p, r were cyclized with malononitrile in the presence of piperidine to yield thiazolo[3,2-a][1,8]naphthryidines 7a, b. Thiazolo-[2′,3′:1,6]pyrido[2,3-d]pyrimidine 9a–cwere obtained by cyclization of compounds 5c, p, r with formic acid. The structure of the synthesized compounds was established by analytical and spectral data. Also, some of the synthesized compounds were screened for antimicrobial activity in vitro.     

Studies on 2-Aminothiophenes: Synthesis,Transformations, and Biological Evaluation of Functionally-Substituted Thiophenes and Their Fused Derivatives

Abstract

Heterocyclic enamines1 reacted with ethyl acetoacetate to afford the corresponding amide derivatives2. Treatment of2 with carbon disulphide yielded the dipotassium salts3which reacted in-situ with a variety of α -haloketones to give the respective substituted thiophenes5,8, and13. The reactivity of the latter products towards various chemical reagents was studied to yield their fused thiophene derivatives7,10,12, and14, respectively. Some representative compounds were tested for antimicrobial activity.     

Synthesis,reactions, and antioxidant activity of 3-(pyrrol-1-yl)-4,6-dimethyl selenolo[2,3-b]pyridine derivatives

Ethyl 4,6-dimethyl-3-(pyrrol-1-yl) selenolo[2,3-b]pyridine-2-carboxylate (2) was synthesized by the reaction of previously prepared ethyl 3-amino-4,6-dimethyl selenolo[2,3-b]pyridine-2-carboxylate (1) with 2,5-dimethoxytetrahydrofuran in acetic acid. The pyrrolyl ester (2) was converted into the corresponding carbohydrazide 3 which reacted with acetyl acetone, aromatic aldehydes, carbon disulfide in pyridine, and sodium nitrite to afford the corresponding dimethyl pyrazolyl 4, arylidene carbohydrazides 5a–d, oxadiazolyl thiole 6, and caboazide compound 8, respectively. The carboazide 8 reacted with different alcohols and amines to give the corresponding carbamates 9a–c and the aryl urea derivatives 10a–d. Heating of carboazide 8 in dry xylene afforded the pyridoselenolo-pyrrolopyrazinone 11. The latter compound was used as a versatile starting precursor for synthesis of other pyridoselenolo-pyrrolopyrazine compounds. The newly synthesized compounds and their derivatives were characterized by elemental analysis and spectroscopy (IR, ¹H-NMR, and mass spectra). Some of the newly synthesized pyrrolyl selenolopyridine compounds showed remarkable antioxidant activity compared to ascorbic acid.     

SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF SOME NEW PYRIDO[3′,2′:4,5]THIENO[3,2-d]- PYRIMIDINE DERIVATIVES

5-Acetyl-3-amino-4-aryl-6-methylthieno[2,3-b]pyridine-2-carboxamides (1a, b) were reacted with aromatic aldehydes or with some cycloalkanones to give the corresponding tetrahydropyridothienopyrimidinone derivatives 2a–f and 4a–d . The reaction of compound 1b with urea and/or carbon disulfide has been carried out and their products were identified. Some representative compounds were screened in vitro for their antimicrobial activities.     

Reaction of 2-Thioxo-4-Thiazolidinones Toward Lawesson's Reagent,Phosphorus Pentasulfide,Dialkylaminophosphines, and Phosphorus Ylides

Abstract

2-Thioxo—3-allyl-4-thiazolidinone 1a reacts with Lawesson's reagent (LR, 2) to give the ethylenic product 5 through a coupling reaction along with the dithioxo compound 6. Coupling reaction products of types 8 and 9 are also produced upon reacting thiazolidinones 1 and with the appropriate tris(diallkylamino) phosphine reagent (3 a,b). Reaction of the thiazolidinone 1a with the ylidenetriphenylphosphorane reagents 4 a–c proceeds according to the Wittig mechanism yielding ethylenes 10a–c, respectively. Structural elucidations for the new products were based upon compatible analytical and spectroscopic measurements as well a confirmatory single crystal X-ray structure for 5.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the related elements to view the free supplemental file.     

SOME REACTIONS OF 3-AMINO-2-CARBOETHOXY-4,6-DIMETHYLTHIENO[2,3-b]-PYRIDINE. SYNTHESIS OF SOME NEW THIENOPYRIDOPYRIMIDINES

Abstract

Thienopyridine oxazinone (1) has been prepared and explored as a precursor by its reaction with some reagents namely, ammonium acetate, aliphatic amines, aromatic amines, hydrazine hydrate, thiosemicarbazide, and ethyl glycinate to give pyridothienopyrimidines (11-VII). The pyrimidinone compound (11) was converted to the 4-chloro derivative (X) by its reaction with excess POCl₃ Interaction of the 4-chlorocompound (X) with some reagents namely, hydrazine hydrate, methyl amine, aniline, sodium thiophenolate, ethyl glycinate, thiosemicarbazide and thiourea, yielded pyridothieno-pyrimidine derivatives (XI-XVII) substituted at 4-position, respectively.     

Synthesis,Reactions, and Characterization of 6-Amino-4-(Benzo[b]Thiophen-2-YL)-2-Thioxo-1, 2-Dihydropyridine-3, 5-Dicarbonitrile

Abstract

Benzothiophene -2- carbaldehyde 1 reacted with 2-cyanoethanethioamide 2 in 1:2 molar ratios to give the corresponding 6-amino-4-(benzo[b]thiophen-2-yl)-2-thioxo-1, 2-dihydropyridine-3,5-dicarbonitrile 6. The synthetic potentiality of compound 6 was investigated via its reaction with active halogen-containing reagents to afford the corresponding thieno[2,3-b]pyridine derivatives 11a,b, 14, 16, and 19. Also, compound 6 reacted with hydrazine hydrate to give the pyrazolo[3,4-b]pyridine derivative 21. Compound 21 condensed with 4-(2-thienyl)benzaldehyde to afford pyrazolo[3,4-b]pyridine derivative 23. Structural elucidation of all the newly synthesized heterocyclic compounds was based on elemental analyses, IR, ¹H NMR, and mass spectra.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Facile synthesis of some new functionalized 2-selenoxopyrimidines

Abstract

Some new functionalized 2-selenoxodihydropyrimidines 1–6 were synthesized in good yields via a simple one-pot reaction. The simple method depended on the reaction of selenourea with some nitrile active methylene compounds under basic-catalyzed conditions. Also, treatment of selenourea with each of malononitrile and ethyl cyanoacetate in the presence of benzaldehyde under the same basic reaction conditions afforded the 2-selenoxopyrimidine-5-carbonitriles 7 and 8, respectively. Furthermore, selenourea reacted with benzaldehyde and different β-dicarbonyl compounds under Biginelli reaction conditions to afford the 2-selenoxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates 10, 11 and 13. Using acetylacetone as a substrate in Biginelli reaction yielded the unexpected 5-benzylidene-4,6-dimethyl-pyrimidine-2(5H)-selenone (14). The structures of the synthesized compounds were established on the basis of elemental analysis, IR, ¹H- and ¹³C-NMR and mass spectral data.     

Studies on organophosphorus compounds: Synthesis and reactions of [1,2,4,3]triaza‐phospholo[4,5‐a]quinoxaline derivative

2,4‐Bis‐(4‐methoxyphenyl)‐1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide (Lawesson's reagent) ( 1 ) reacted with 2‐hydrazino‐3‐methyl‐quinoxaline ( 2 ) to give [1,2,4,3]‐triazaphospholo[4,5‐a]quinoxaline derivative 3 . The Mannich reaction using different amines on compound 3 gave Mannich bases 4a–d . Also, compound 3 reacted with formaldehyde to give the corresponding 2‐hydroxymethyl derivative 5 , which upon reaction with thionyl chloride gave the corresponding chloromethyl derivative 6 . Treatment of compound 6 with some thiols yielded the corresponding sulfides 7a–d . Acylation of compound 3 gave acylated compounds 8a,b . Compound 9 , which was prepared through the reaction of compound 3 with ethyl cyanoacetate, was investigated as a starting material for the synthesis of some new heterocyclic systems 10–13 . Also, reaction of compound 9 with carbon disulfide and 2 equivalents of methyl iodide in a one‐pot reaction yielded the corresponding ketene‐S,S‐acetal 14 , which in turn reacted with bidentates to give some new heterocycles 15–17 . © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:520–529, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20473     

Synthesis of Some Pyridothienopyrazolopyrimidopyrimidine and Mercaptomethylpyrazolopyrimidine Derivatives

Mercaptomethylpyrazolopyrimidine (2) was synthesized and reacted with ethyl chloroacetate to afford ethyl pyrazolpyrimidinylmethylmercapto acetate ( 3) , which in turn was converted into the corresponding carbohydrazide 4 . Carbohydrazide 4 reacts with a variety of reagents to give different pyrazolopyrimidines ( 5–12 ). Chloromethyl-pyrazolopyrimidine (1) reacts with chloropyridine to give compound 13 , which was subjected in a series of reactions to give new compounds 14–20 .     

Synthesis of fused 1,2,4-triazines as potential antimicrobial and antitumor agents

5-Benzylidene-3-(p-chlorophenyl)-2-aminothiocarbonyl-1,2,4-triazine (2) was prepared via condensation of oxazolinone (1) with thiosemicarbazide. Fused 1,2,4-triazine derivatives (3, 4 and 9) were synthesized from the reaction of compound 2 with ω-bromomethyl aryl ketones, ethyl chloroacetate, and acetic anhydride. Treatment of 4 with acetic anhydride and aromatic aldehydes yielded the corresponding acetyl, diacetyl derivatives (6 and 7) and 7-benzylidene-5-(p-chlorophenyl)-4-thioxo-3-arylidene-1,2,4-triazino [2,1-a]-1,2,4-triazine-1,8-diones (8). The electron impact mass spectra of both the above series of compounds have also been recorded and their fragmentation pattern is discussed. All synthesized fused 1,2,4-triazine derivatives were primary in vitro screened for their antimicrobial and antitumor activity.

     

PYRAZOLONES AS VERSATILE PRECURSORS FOR THE SYNTHESIS OF FUSED AND BINARY HETEROCYCLES

The reaction of pyrazolone bearing a β-ketoester moiety with aliphatic dibasic functional reagents in ethanol afforded the binary ring heterocycles 2, 6, and 10. Whereas, when using an excess of the dibasic reagent, the dipyrazolo [3,4-c: 3′, 4′-f] [1,2]diazepine derivative 5 was, obtained. On the other hand, when compound 1 reacted with hydrazine hydrate in acetic acid, it furnished the pyrazolo[3,4-b]pyridine derivative 7 in which the hydrazine hydrate acts as a monofunctional reagent. Also, the reaction of 1 with m-anisidine according to Knorr synthesis gave the α,β-unsaturated ketone derivative 9 in lieu of the anticipated quinolone derivative 8. Furthermore, treatment of compound 1 with aromatic dibasic functional reagents afforded 11 and 13. Eventually, compound 11 was annelated through its reaction with ammonium carbonate to give pyrazolo[3,4-b]pyrido[6,5-b]benzodiazepin 12.