Synthesis and Spectral Characterization of Some Novel Thiazolyl-Pyrazoline Derivatives Containing 1,2,3-Triazole Moiety

Abstract

A series of novel 3-aryl-5-(2-aryl-1,2,3-triazol-4-yl)-1-(4-aryl-2-thiazoyl)-pyrazolines 6a–6r were synthesized using 2-aryl-4-formyl-1,2,3-triazoles 1a,b as the starting materials. Thus, reacting 1a,b with 1-arylethanones 2a–2c gave 1-aryl-3-(2-aryl-1,2,3-triazol-4-yl)-2-propen-1-ones 3a–3f. The reaction of the latter with thiosemicarbazide afforded 3-aryl-5-(2-aryl-1,2,3-triazol-4-yl)-1-thiocarbamoyl-pyrazolines 4a–4f, which condensed with 2-bromo-1-arylethanones 5a–5c to afford the target compounds 6a–6r. The chemical structures of the compounds were verified by means of their IR, ¹H NMR, ESI-MS spectroscopic data, and elemental analysis.

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GRAPHICAL ABSTRACT     

Synthesis of Some New N‐Substituted Pyrroles,Pyrrolo[1,2‐a]quinazoline,and Diaza‐as‐indacene Derivatives

2‐Phenyl‐1,1,3‐tricyano‐3‐bromopropene 1 reacts with the aromatic amines 2a–f and 6a–c to afford the N‐substituted pyrroles 4a–d, the pyrrolo[1,2‐a]quinazoline derivatives 5a, b, and the diaza‐as‐indacene derivatives 7a–c and 8a–c, presumably via elimination of hydrogen bromide followed by cyclization of the formed acyclic intermediates. All structures are confirmed by analytical and spectral data.     

Studies on Pyrazine Derivatives,XLIV: Synthesis and Tuberculostatic Activity of 4-Substituted 3,4,5,6-Tetrahydro-2H-[1,2′]-Bis-Pyrazine Derivatives

2-chloro-3-cyanopyrazine was a substrate in the syntheses of some potentially tuberculostatic pyrazine derivatives. This compound, upon action of secondary amines, pyrazine derivatives 1-phenyl-, 1-piperonyl-, 1-(4-fluorophenyl)-, 1-(2-pyridil)-, and 1-benzylpiperazine, gave the corresponding nitriles ( 1a–e ). Compounds 1c , d , e were changed into the amidoximes ( 2c , d , e ) by hydroxylamine action. Derivatives 1a–e were transformed into the corresponding thioamides ( 3a–e ) when treated with ammonium polysulphide. Two of these, thioamides, 3a and 3b , in the cyclization reactions with ethylenediamine gave the imidazolines ( 4a , b ) with phenacyl bromide—the thiazole derivatives ( 5a , b ). The compounds obtained were tested in vitro for their tuberculostatic activity. The tuberculostatic activity of compound 5b was the highest: MIC 3.1–7.8 μ g/mL.     

Synthesis and Antiviral Evaluation of Some 5‐N‐Arylaminomethyl‐2‐glycosylsulphanyl‐1,3,4‐oxadiazoles and Their Analogs against Hepatitis A and Herpes Simplex Viruses

N‐Arylaminomethyl‐3H‐1,3,4‐oxadiazole‐2‐thiones 2a,b were prepared from the corresponding N‐arylglycinoylhydrazides. A number of their thioglycoside derivatives 4–7a–c and S‐functionalized analogs 8–11a,b were synthesized by the reaction with different acetobromosugars and acyclic hydroxyalkylating agents. The antiviral activity of a number of the synthesized compounds against herpes simplex virus type 1 (HSV‐1) and hepatitis A virus (HAV) was evaluated. Compounds 5a and 5b showed promising results against HAV.     

STUDIES ON THIAZOLOPYRIDINES. PART 5: SYNTHESIS OF HITHERTO UNKNOWN THIAZOLINONE AND THIAZOLO[3,2-a]PYRIDINE DERIVATIVES HAVING IN THEIR STRUCTURE THE MORPHOLIN-4-YL MOIETY

Condensation of thiazolinone 1 with benzaldehydes 2a, b in ethanolic piperidine afforded the methylidene derivatives 3a, b. Cyclocondensation of compound 3b with malononitrile furnished the novel thiazolo[3,2-a]-pyridine 5. Also, compound 3b was condensed with dimethylformamide-dimethylacetal (DMF-DMA) and triethylortho-formate to yield N,N-dimethylamino 6 and ethoxymethylene 7 derivatives respectively. The novel thiazolo[3,2-a]pyridines 10a, b were obtained by cyclocondensation of compounds 3a, b with benzylidene-malononitriles 8a, b. Similarly, cyclocondensation of compound 3b with benzylidenemalononitrile 11 afforded the thiazolopyridines 12a–c. Ternary condensation of compound (12), 4-morpholinobenzaldehyde 2b and malononitrile (1:1:1 molar ratio) produced the thiazolopyridines 14a–c. When compound 10b was subjected to react with malononitrile in dioxane/piperidine under reflux the novel condensed heterocyclic system 18 was obtained. Treatment of ortho-aminocarbonitrile 10b with formic acid, aromatic aldehyde and triethylorthoformate furnished the thiazolo[2′,3′:1,6] pyrido[2,3-d] pyrimidine 20, azomethine 21a, b and ethoxymethylene 22 derivatives respectively. The structure of the synthesized compounds was established by analytical and spectral data.     

Synthesis and Antimicrobial Activities of Some 6-Methyl-3-Thioxo-2,3-Dihydro-1,2,4-Triazine Derivatives

Abstract

4-Arylidene-imidazole derivatives (4a,b) were readily prepared by reacting 4-am- ino-6-methyl-3–thioxo-2,3–dihydro[1,2,4]triazin-5(4H)-one (1) with 4-arylidene-2-phenyl- 4H-oxazol-5-one (2). Reaction of 1 with some aromatic aldehydes in presence of triethylphosphite exclusively afforded the corresponding aminophosphonates 5a-c. Reaction of 1 with 3-phenyl-1H-quinazoline-2,4-dione (6a) and/or 3-phenyl-2-thioxo-2,3-dihydro- 1H-quinazolin-4-one (6b) gave 2-(6-methyl-5-oxo-3-thioxo-2,5-dihydro-3H-[1,2,4]triazin-4-ylimino)-3-phenyl-2,3-dihydro-1H-quinazolin-4-one (7). Moreover, on treating 1 with 2-phenylbenzo[d][1,3]thiazine-4-thione (8), 6-methyl-4-(2-phenyl-4-thioxo-4H-quinazolin-3-yl)-3-thioxo-3,4-dihydro-2H-[1,2,4]triazine-5-one (9) was obtained in 65% yield. Reaction of 1 with 4-sulfonylaminoacetic acid derivatives (10a,b) afforded the corresponding sulfonamides (11a,b), respectively. Acid hydrolysis of 11a afforded 7-aminomethyl-3-methyl[1,3,4]thiadiazole[2,3-c][1,2,4]triazin-4-one (12). 4-Amino-6-methyl-3-(morpholine-4-ylsulfanyl)-4H-[1,2,4]triazin-5-one (14) was prepared by reacting compound 1 with morpholine in presence of KI/I₂, while 3,3′-bis(4-amino-6-methyl-5-oxo-triazinyl)disulfide (16) was obtained by oxidation of 1 with lead tetraacetate. The antimicrobial activity of the products was evaluated against Gram-positive and Gram-negative bacteria as well as the fungus Candida albicans.

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The Synthesis of Some Pyrazolyl- and Thiazolylthienopyridines

2-acetyl-3-amino-4,6-dimethylthieno[2,3-b]pyridine 1 reacted with dimethoxy-tetrahydrofuran in acetic acid and ethyl cyanoacetate in the presence of ammonium acetate or with NaNO₂ in the presence of an AcOH/HCl mixture to produce 2–4. Compound 2 reacted with aromatic aldehydes, semicarbazide hydrochloride, thiosemicarbazide, and phenyl hydrazine or with hydrazine hydrate to give compounds 5a–c and 11a–d, respectively.

Chalcone 5 reacted with hydrazines, hydroxylamine hydrochloride, or thiourea to produce compounds 6–9. Thiosemicarbazone 11b reacted with α -haloester to produce the corresponding thiazolidinone derivatives 12a, b ; also it reacted with ω -bromoacetophenone to give thiazoline derivatives 13a, b .     

Activated Nitriles in Heterocyclic:Synthesis Novel Syntheses of Imidazo[2,1-b]-1,3-Thiazine Derivatives

Abstract

Several new imidazo[2,1-b]-1,3-thiazine derivatives 4a–c, 8a–c, and 11a–c were synthesised via the reaction of 5,5-diphenyl-2-thiohydantoin (1) with αβ -unsaturated nitriles 2a–c, 5a–c, and 9a–c. The structures of the products were established on the basis of elemental analyses, IR, and ¹H-NMR spectral data.     

Pyridine-2(1H)-thione in Heterocyclic Synthesis: Synthesis of Some New Nicotinic Acid Ester,Thieno[2, 3-b]pyridine,Pyrido[3′, 2′: 4, 5]thieno [3, 2-d]pyrimidine,and Thiazolylpyrazolo[3, 4-b]pyridine Derivatives

Nicotinic acid esters 3a–c were prepared by the reaction of pyridine-2(1H)-thione derivative 1 with α-halo-reagents 2a–c. Compounds 3a–c underwent cyclization to the corresponding thieno[2, 3-b]pyridines 4a–c via boiling in ethanol/piperidine solution. Compounds 4a–c condensed with dimethylformamide-dimethylacetal (DMF-DMA) to afford 3-{[(N,N-dimethylamino)methylene]amino}thieno[2, 3-b]- pyridine derivatives 6a–c. Moreover, compounds 4a–c and 6a–c reacted with different reagents and afforded the pyrido[3′,2′:4, 5]thieno[3, 2-d]pyrimidine derivatives 10a–d, 11a–c, 12a,b, 14a,b, 17, and 19. In addition, pyrazolo[3, 4-b]pyridine derivative 20 (formed via the reaction of 1 with hydrazine hydrate) reacted with ethylisothiocyanate yielded the thiourea derivative 21. Compound 21 reacted with α-halocarbonyl compounds to give the 3-[(3H-thiazol-2-ylidene)amino]-1H-pyrazolo[3, 4-b]pyridine derivatives 23a–c, 25, and 27a,b.     

A CONVENIENT SYNTHESIS OF 1,3-DISUBSTITUTED-4-(1′,3′-DITHIOLANE/DITHIANE-2′-YLIDENE)-2-PYRAZOLIN-5-ONES

1, 3 - Disubstituted- 4 - (1′, 3′- dithiolane /dithiane - 2′- ylidene) - 2 -pyrazolin-5-one derivatives like (1a–c), (2a–c), (3a–c) have been obtained by condensation of 2-pyrazolin-5-ones (1), (2) and (3) with carbon disulfide in presence of triethylamine followed by the reaction with 1,2-dibromoethane (4a), 1,3-dibromopropane (4b) and 1,3-dibromobutane (4c) respectively.     

SYNTHESIS OF NEW 3-SUBSTITUTED AND SPIRO 1,5-BENZODIAZEPIN-2-ONES UNDER PHASE-TRANSFER CATALYSIS CONDITIONS

1,3-Dihydro-4-phenyl-1,5-benzodiazepin-2-one 1 was treated with bromine in 1:1 molar ratio to get the corresponding 3-bromo derivative 2 which in turn reacted with different nucleophiles to get the corresponding 3-substituted derivatives 3–11. The cyclized compounds 4_a , 5_a , 7_a,b , and 9_a–c were achieved on refluxing compounds 4, 5, 6_a,b , or 8 _a–c respectively in diphenyl ether. Compound 1 was benzoylated with benzoyl chloride to give the corresponding 1-benzoyl derivative 12 which reacted with bromine in 1:2 molar ratio to yield the corresponding 3,3-dibromo derivative 13. Spiro benzodiazepines 14_a–d–16 were obtained by reacting compound 13 with the proper bidentates. Compound 1 was treated with formaldehyde and secondary amines or thiols to give Mannich bases or sulphides 17–21, respectively.     

Synthesis,antimicrobial and anticancer activities of some new N-methylsulphonyl and N-benzenesulphonyl-3-indolyl heterocycles: 1st Cancer Update

A series of 1-(N-methyl 2a–c and N-benzenesulphonyl-1H-indol-3-yl)-3-aryl-prop-2-ene-1-ones 3a–c were prepared and allowed to react with urea, thiourea or guanidine and gave the pyrimidine derivatives 4a–c to 9a–c. Base catalyzed reaction of 2a–c or 3a–c with ethyl acetoacetate gave cyclohexanone derivatives 10a–c and 11a–c, respectively. Reaction of the latter compounds with hydrazine hydrate afforded indazole derivatives 12a–c and 13a–c, respectively. On the other hand, condensation of 2c or 3c with some hydrazine derivatives namely, hydrazine hydrate, acetyl hydrazine, phenyl hydrazine and benzyl hydrazine hydrochloride gave pyrazole derivatives 14a,b-17a,b, respectively. Moreover, reaction of 2c or 3c with hydroxyl amine hydrochloride gave isoxazole derivatives 18a,b. The newly synthesized compounds were tested for their antimicrobial activity and showed that, compounds 14a, 14b, 15a and 15b were found to be the most active ones of all the tested compounds toward Salmonella typhimurium (ATCC 14,028) compared to the reference drug chloramphenicol. Eighteen new compounds namely, pyrimidin-2(1H)-ones 4a–c and 5a–c, pyrimidin-2(1H)-thiones 6a–c and 7a–c and pyrimidin-2-amines 8a–c and 9a–c were tested for their in vitro cytotoxicity against human liver carcinoma (HEPG2), human breast cancer (MCF7) and human colon cancer (HCT-116) cell lines and showed that, compounds 4c, 5c, 6c, 8c and 9c were found to be the highly active compounds compared to the reference drug doxorubicin.     

Microwave promoted improved regioselective synthesis of 1H,3H,6H[2]benzopyrano[4,3-d]pyrimidine-2,4-diones by radical cyclisation

In this work, two new effective methodologies have been adopted for the preparation of 5-(2′-bromobenzyloxy)pyrimidine-2,4-diones 6(a–k). In the first methodology, 5-hydroxy uracils 4(a–f) were alkylated with 2-bromobenzyl bromide 5a or 2-bromo-5-methoxy benzyl bromide 5b under phase transfer catalysis condition using lithium hydroxide/tetrabutyl ammonium bromide in N,N-dimethylformamide at 45 °C, and in the second method, the microwave irradiation (MWI) protocol has been exploited by mixing 5-hydroxy uracils 4(a–f) with 30 % excess of 2-bromobenzyl bromide 5a or 2-bromo-5-methoxy benzyl bromide 5b. A catalytic amount of TBAB and potassium carbonate was added and irradiated in an open Erlenmeyer flask in a microwave oven for 3–12 min. The tributyltin hydride-mediated radical cyclisation of 6(a–k) was carried out under MWI to generate 1H,3H,6H[2]benzopyrano[4,3-d]pyrimidine-2,4-diones 7(a–k) in 80–89 % yield, and the reaction time was shortened compared to the previously reported conventional radical cyclisation method.     

Synthesis of some fused heterocyclic systems and their nucleoside candidates

A series of pyridofuro compounds were synthesized from 4-(4-chlorophenyl)-1,2-dihydro-2-oxo-6-(thiophen-2-yl)pyridine-3-carbonitrile (1) as starting material. Alkylation of 1 with ethyl bromoacetate gave the corresponding ester 2, which was condensed with hydrazine hydrate to afford the corresponding acid hydrazide derivative 3. Thrope-Ziegler cyclization of 2 with sodium methoxide gave furo[2,3-b]pyridine derivative 4, which was reacted with thiosemicarbazide, allyl isothiocyanate, formamide or hydrazine hydrate to give furopyridine derivatives 5–8, respectively. The latter compound 8 was cyclized with acetylacetone or formic acid to give the corresponding compounds 9 and 10, respectively. Furthermore, sulfurization of 1 with P₂S₅ gave the corresponding thioxopyridine 11, which was reacted with glycosyl (or galactosyl) bromide, morpholine or piperidine to give the corresponding thioglycoside 12a,b and Mannich base 14a,b derivatives. The deacetylation of 12a,b gave the corresponding deacetylated thioglycosides 13a,b, respectively. All the newly synthesized compounds were characterized by the elemental analyses and spectroscopic evidences (IR, ¹H- and ¹³C NMR).     

SOME NEW S-, S,S- AND N,S-SUBSTITUTED 2-NITRODIENES AND BUTADIENYL-SUBSTITUTED PIPERAZINES

Nitrodiene 1 reacted with 2a, b and gave the novel compounds 3a, b, 4a, b, and 5a. Monosubstituted diene compound 3a gave the compounds 9a with morpholine, 11a with piperidine, and 13a with homopiperazine. Compound 3a gives the thioether compound 15 by the reaction with the dithiol (HS─(CH₂)₂─O─(CH₂)₂─SH) in ethanol containing sodium hydroxide.     

THE NOVEL MACROCYCLIC AND LINEAR-CHAIN THIOETHERS FROM PERCHLOROBUTADIENE AND DITHIOLES

Compounds 3a–c, 4a, b, 5a–c, and 6a, c were obtained from the reactions of perchlorobutadiene (1) with 1,4-butanedithiol (2a), 1,5-pentanethiol (2b), and 2.2′-(ethlene-dioxyl)diethanethiol (2c) in ethanol in the presence of sodium hydroxide. Compounds 7a, b were obtained from the reactions of thioethers 3a, b with m-chlorperbenzoic acid in CHCl ₃ .     

Novel Synthesis of N-Arylpyrrole,Pyrrolo[1,2-a]quinazoline,and Pyrrolo[3,4-d]pyridazine Derivatives

Phenacyl-malononitrile derivatives 1a,b react with dimethyl formamide dimethyl acetal (DMFDMA) in refluxing toluene to afford the enaminones 2a,b respectively. Compounds 2a and 2b react with the aromatic amines (aniline, p-toluidine, p-anisidine) in refluxing ethanol to afford the pyrroles 4a–f and with anthranilonitrile and methyl anthranilate to afford the pyrrolo[1,2-a]quinazolines 5a,b and 6a,b respectively. The pyrrole derivatives 4a–f react with hydrazine hydrate and phenyl hydrazine in refluxing ethanol to afford the pyrrolo[3,4-d] pyridazine derivatives 7a–f and 8a–f respectively.