Microwave-assisted synthesis of 1-{2-[(1-benzyl-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-4-yl)methoxy]phenyl}-3-(3-aryl-1-phenyl-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-4-yl)prop-2-en-1-ones and their antimicrobial activity

A series of new (E)-1-{2-[(1-benzyl-1H-1,2,3-triazol-4-yl)methoxy]phenyl}-3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones (3a–3i) has been synthesized via copper-catalyzed 1,3-dipolar azide-alkyne cycloaddition reaction (CuAAC) of benzyl azide with substituted (E)-3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-1-[2-(prop-2-ynyloxy)phenyl]prop-2-en-1-ones (2a–2i). The synthesized compounds have been characterized by their IR, ^lH, ¹³C NMR spectra, and mass spectroscopy data. All the compounds have been screened for antimicrobial activity.     

Synthesis,characterization, and antimicrobial activity of novel (<Emphasis Type="Italic">E</Emphasis>)-1-(aryl)-3-{3, 5-dimethoxy-4-[(1-(aryl)-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-4-yl)methoxy]phenyl}prop-2-en-1-ones

The new chalcone derivatives containing the 1,2,3-triazole ring system, namely, (E)-1-(aryl)-3-{3,5-dimethoxy-4-[(1-(aryl)-1H-1,2,3-triazol-4-yl)methoxy]phenyl}prop-2-en-1-ones, were synthesized in 65–88% yield by the “click chemistry” reactions of substituted acetophenones, 4-hydroxy-3,5-dimethoxy-benzaldehyde, and different substituted azides. The structure of the compounds was determined by the FT-IR, ¹H NMR, ¹³C NMR, and mass spectroscopic analyses. Compounds 6a–6l were screened for in vitro antimicrobial activity by the agar disc diffusion method.     

Ultrasound- and microwave-assisted synthesis of (E)-1-aryl-3-[2-(piperidin-1-yl)quinolin-3-yl]prop-2-en-1-ones and (E)-1-aryl-3-[2-(pyrrolidin-1-yl)quinolin-3-yl]prop-2-en-1-ones,and their antimicrobial activity

Series of new (E)-1-aryl-3-[2-(piperidin-1-yl)quinolin-3-yl]prop-2-en-1-ones and (E)-1-aryl-3-[2-(pyrrolidin-1-yl)quinolin-3-yl]prop-2-en-1-ones have been efficiently prepared via the Claisen-Schmidt condensation of 2-(piperidin-1-yl)quinoline-3-carbaldehyde and 2-(pyrrolidin-1-yl)quinoline-3-carbaldehyde, respectively, with aryl methyl ketones under conditions of ultrasound and microwave irradiation. Structures of the products have been confirmed by IR, ¹H NMR, ¹³C NMR, and mass spectroscopy, as well as by elemental analysis. Evaluation of the in vitro antibacterial activity against bacterial (Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli) and fungal (Aspergillus niger and Candida metapsilosis) strains has revealed good antimicrobial activity of some of the tested compounds.     

1,5-Electrocyclization of 1-alkyl- 3-[(2Z)-2,4-diaryl-4-oxobut-2-en-1-yl]-1H-benzimidazol-3-ium bromides

Cyclization of 1-alkyl-3-[(2Z)-2,4-diaryl-4-oxobut-2-en-1-yl]-1H-benzimidazol-3-ium bromides occurs in the presence of MeONa at a reduced temperature of 5–10°C via a 1,5-electrocyclization mechanism to give 3a,4-dihydro-3H-pyrrolo[1,2-a]benzimidazoles. These are unstable under the reaction conditions and are readily converted to {1-[2-(alkylamino)phenyl]-4-phenyl-1H-pyrrol-3-yl}(phenyl)methanones.     

Synthesis and characterization of some chalcones and their cyclohexenone derivatives

A series of chalcones and their derivatives have been synthesized. Chalcones, 1-(1,3-benzodioxol-5-yl)-3-(aryl)-prop-2-en-1-ones were prepared by the aldol condensation of 1-(1,3-benzodioxol-5-yl)ethanones and aryl aldehydes. Based-catalyzed condensation of 1-(1,3-benzodioxol-5-yl)-3-(aryl)prop-2-en-1-ones with ethyl acetoacetate yields corresponding ethyl 4-(1,3-benzodioxol-5-yl)-6-(aryl)-2-oxocyclohex-3-ene-1-carboxylates. Some of the synthesized chalcones were reported in the literature; the newly synthesized compounds were characterized by single crystal X-ray studies, IR, ¹H-NMR and LCMS mass spectral analysis.     

A facile synthesis of novel 3-(aryl/alkyl-2-ylmethyl)-2-thioxothiazolidin-4-ones using microwave heating

(Z)-5-(2-(1H-Indol-3-yl)-2-oxoethylidene)-3-(aryl/alkyl-2-ylmethyl)-2-thioxothiazolidin-4-ones (7a–w) have been synthesized by the Knoevenagel condensation reaction of 3-(aryl/alkyl-2-ylmethyl)-2-thioxothiazolidin-4-ones (3a–d) with suitably substituted 2-(1H-indol-3-yl)2-oxoacetaldehydes (6a–g) under microwave conditions. The thioxothiazolidin-4-ones were prepared from the corresponding aryl/alkyl amines (1a–d) and di-(carboxymethyl)-trithiocarbonyl (2). The aldehydes (6a–g) were synthesized from the corresponding acid chlorides (5a–g) using HsnBu₃.     

Microwave assisted synthesis of substituted (<Emphasis Type="Italic">Z</Emphasis>)-2-{[1-phenyl-3-(thiophen-2-yl)-1<Emphasis Type="Italic">H</Emphasis>-pyrazol- 4-yl]methylene}benzofuran-3(2<Emphasis Type="Italic">H</Emphasis>)-ones and their antimicrobial activity

Aurones, pyrazole and thiophene scaffolds are known for their potential antimicrobial activity. Herein, we have synthesized hybrid compounds containing three substituted (Z)-2-{[1-phenyl-3-(thiophen-2-yl)- 1H-pyrazol-4-yl]methylene}benzofuran-3(2H)-ones that had been produced from substituted (E)-1-(2-hydroxyphenyl)- 3-[1-phenyl-3-(thiophen-2-yl)-1H-pyrazol-4-yl]prop-2-en-1-ones in high yields. All synthesized compounds were tested in vitro for their antimicrobial activity. Several of those demonstrated promising activity against some fungal and bacterial strains.     

Gram-scale synthesis of anti-pancreatic flavonoids (±)-8-[1-(4′-hydroxy-3′-methoxyphenyl)prop-2-en-1-yl]-chrysin and -galangin

Gram-scale total synthesis of (±)-8-[1-(4′-hydroxy-3′-methoxyphenyl)prop-2-en-1-yl]-galangin (1) and -chrysin (2) has been accomplished in eight steps from commercially available phloroglucinol and three steps from commercially available chrysin, respectively, featuring an efficient introduction of C(8) (1-prop-2-en-1-yl)phenyl moiety in the natural products through chemo- and regioselective cinnamylation and regioselective aromatic Claisen rearrangement.     

Azolyl-substituted 1,2,3-triazoles

Huisgen reaction of (E)-1,5-diarylpent-2-en-4-yn-1-ones and (E)-1,5-diarylpent-1-en-4-yn-3-ones afforded 1-aryl-3-(5-aryl-1H-1,2,3-triazol-4-yl)prop-2-en-1-ones and 3-aryl-1-(5-aryl-1H-1,2,3-triazol-4-yl)-prop-2-en-1-ones, respectively. (E)-1-Aryl-3-(5-phenyl-1H-1,2,3-triazol-4-yl)prop-2-en-1-ones reacted with hydrazine hydrate and phenylhydrazine to give 72–93% of 4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-5-phenyl-1H-1,2,3-triazoles which underwent dehydrogenation on heating in boiling acetic acid with formation of the corresponding pyrazole derivatives. The molecular structures of (E)-3-phenyl-1-(5-phenyl-1H-1,2,3-triazol-4-yl)prop-2-en-1-one and 4-[3-(4-methylphenyl)-1-phenyl-4,5-dihydro-1H-pyrazol-5-yl]-5-phenyl-1H-1,2,3-triazole were studied by X-ray analysis. 4-(3-Aryl-4,5-dihydro-1H-pyrazol-5-yl)-5-phenyl-1H-1,2,3-triazoles showed toxicity against Daphnia magna.     

13C NMR spectra of some 1,2-disubstitutedN-vinyl-1H-1,2,4-triazoles

¹³C NMR spectra (20 and 75 MHz, in DMSO-d₆) of a series of 1,3-diaryl-3-(1H-1,2,4-triazol-1-yl)- and 1,3-diaryl-2-(1H-1,2,4-triazol-1-yl)prop-2-en-1-ones were registered. It was shown that the chemical shifts of both the carbon atom of the alkene group and C(3) reflect regio- and stereoisomerism of these compounds. Taking this into account the isomeric structures of several 1,3-diaryl-3-(1H-1,2,4-triazol-1-yl)prop-2-en-1-ones were identified and the configurations relative to the double bond of a number of 1,3-diaryl-2-(1H-1,2,4-triazol-1-yl)prop-2-en-1-ones were determined.     

Synthesis,studies and in vitro antibacterial activity of some 5-(thiophene-2-yl)-phenyl pyrazoline derivatives

In the present investigation, a novel series of pyrazolines 2a–2d were synthesized by the cyclization of various -1-[2-(alkoxy) phenyl]-3-(thiophen-2-yl) prop-2-en-1-one 1a–1d with N-substituted phenyl hydrazine and thiosemicarbazide in the presence of CH₃COOH and NaOH in ethanol which lead to the formation of new pyrazolines. The structures of these compounds were elucidated by, IR, ¹H-NMR, ¹³C-NMR, ESI-MS spectral data and their purities were confirmed by elemental analyes. The in vitro antibacterial activity of these compounds was evaluated against two Gram-positive and two Gram-negative bacteria Aeromonas hydrophila, Yersinia enterocolitica, Listeria monocytogenes, and Staphylococcus aureus by microdilution method and then the minimum inhibitory concentration (MIC) of these compounds was determined. The results showed that compounds 1-[2-(benzyloxy) phenyl]-5-(thiophen-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl (2b) and 1-[2-(naphthalen-2-ylmethoxy) phenyl]-5-(thiophene-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole-4-yl (2d) showed most promising antibacterial activity as compared to the antibiotics gentamicin and tetracycline in (Table 1, Table 2).     

Microwave Assisted Synthesis and Antimicrobial Activity of (E)-1-{2/3/4-[(1-Aryl-1H-1,2,3-triazol-4-yl)methoxy]phenyl}-3-(2-morpholinoquinolin-3-yl)prop-2-en-1-ones

Russian Journal of General Chemistry - A novel series of (E)-1-{2/3/4-[(1-aryl-1H-1,2,3-triazol-4-yl)methoxy]phenyl}-3-(2-morpholinoquinolin-3-yl)prop-2-en-1-ones is synthesised from terminal...     

Synthesis and characterization of novel 2-(1-benzyl-3-[4-fluorophenyl]-1H-pyrazol-4-yl)-7-fluoro-4H-chromen-4-one derivatives

Novel 1-benzyl-3-(4-fluorophenyl)-1H-pyrazole-4-carbaldehydes 3a to 3e were synthesized via Vilsmeier-Haack reaction of the appropriate 1-benzyl-2-(1-(4-fluorophenyl)ethylidene)hydrazines, derived from 4-fluoroacetophenone 1 with substituted 2-benzylhydrazines 2a to 2e . The base catalyzed condensation of 1-benzyl-3-(4-fluorophenyl)-1H-pyrazole-4-carbaldehydes 3a to 3e with 1-(4-fluoro-2-hydroxyphenyl)ethanone 4 gave (E)-3-(1-benzyl-3-(4-fluorophenyl)-1H-pyrazol-4-yl)-1-(4-fluoro-2-hydroxyphenyl)prop-2-en-1-ones 5a to 5e . On cyclization with dimethyl sulfoxide (DMSO)/I₂, compounds 5a to 5e gave 2-(1-benzyl-3-(4-fluorophenyl)-1H-pyrazol-4-yl)-7-fluoro-4H-chromen-4-ones 6a to 6e . Structures of all novel compounds were confirmed by infrared (IR), proton nuclear magnetic resonance (¹H NMR), carbon nuclear magnetic resonance (¹³C NMR), and mass spectral data. All the synthesized compounds were screened for their antibacterial activities.     

Synthesis of some 1- and 2-carboxyalkyl substituted benzimidazoles and their derivatives

Mono- and disubstituted benzimidazoles were synthesized during alkaline hydrolysis or reactions with ethyl chloroacetate of 1-phenyl substituted 4-(1H-benzimidazol-2-yl)-2-pyrrolidinones. The properties of the synthesized ethyl-[2-(1-(substituted phenyl)-5-oxopyrrolidinyl-3-yl)-1H-benzimidazolyl]ethanoates have been investigated and their benzimidazolium chlorides, 1-carboxymethylbenzimidazoles, condensation products of 2-{2-[1-(3-methylphenyl)-5-oxo-3-pyrrolidinyl]-1H-benzimidazol-1-yl}acetohydrazide with various aromatic aldehydes and aliphatic ketones have been obtained.     

Hypervalent triphenyl and diphenyl tin coordination compounds derived from 2-(1H-benzimidazol-2-yl)phenol

Reactions of 2-(1H-benzimidazol-2-yl)phenol (1) and SnPh₃Cl, SnPh₂Cl₂ and SnCl₄ were investigated. One tetracoordinated triphenyltin(IV) compound: triphenyltin-2-(1H-benzimidazol-2-yl)phenolate] (3) and its adducts: [O → Sn] dimethylsulfoxide triphenyltin-[2-(1H-benzimidazol-2-yl)phenolate] (4), [O → Sn] aqua triphenyltin-[2-(1H-benzimidazol-2-yl)phenolate] (5) [O → Sn] ethanol triphenyltin-[2-(1H-benzimidazol-2-yl)phenolate] (6), [N → Sn] pyridine triphenyltin-[2-(1H-benzimidazol-2-yl)phenolate] (7), where 1 acts as a monodentate ligand bound through the phenol oxygen, were obtained. In the pentacoordinated compounds 4-7, the tin atom has tbp geometry. The three phenyl groups are in equatorial positions, whereas the benzimidazole and the Lewis base are in apical positions. Two hexacoordinated tin compounds: diphenyltin-bis[2-(1H-benzimidazol-2-yl-κN)phenolate-κO] (8), dichlorotin-bis[2-(1H-benzimidazol-2-yl-κN)phenolate-κO] (9) bearing two bidentate ligands are reported. The coplanar ligands in 8 and 9 form six membered rings by oxygen and nitrogen coordination. The tin geometry is all-trans octahedral. In 8 the two phenyl groups, and in 9 the two chlorine atoms are perpendicular to the plane of the ligands. Compounds were identified in solution mainly by ¹H, ¹³C and ¹¹⁹Sn NMR and in the solid state by X-ray diffraction analysis.     

Iron pentacarbonyl assisted photochemical route to 2,5- and 2,6-divinyl-substituted 1,4-benzoquinones from 1-ene-3-ynes

Photochemical reaction between the enynes, (Z)-1-methoxybut-1-ene-3-yne, 1 or isopropenyl acetylene, 2 with CO in presence of Fe(CO)₅ yields the 2,6- and 2,5-divinyl-substituted 1,4-benzoquinones: 2,6-bis{(Z)-2-methoxyvinyl}-1,4-benzoquinone (3, 42%), 2,5-bis{(Z)-2-methoxyvinyl}-1,4-benzoquinone (4, 31.5%), [{η²,η²:2,6-di(prop-1-en-2-yl)-1,4-benzoquinone}tricarbonyliron] (5, 45%), and {η²,η²:2,5-di(prop-1-en-2-yl)-1,4-benzoquinone}tricarbonyliron] (6, 65%).     

Synthesis and in-vitro-antibacterial activity of [5-(furan-2-yl)-phenyl]-4,5-carbothioamide-pyrazolines

Cyclization of various different alkoxy [1-[2-(alkoxy)phenyl]-5-(furan-2-yl)-prop-2-en-1-one] chalcone with thiosemicarbazide in the presence of NaOH in ethanol afforded a series of novel 1-N-substituted cyclized pyrazoline analogues [5-(furan-2-yl)-3-[2-(alkoxy) phenyl]-4,5-dihydro-1H-pyrazole-1-carbothioamide 2a–2d. The structures of these compounds were elucidated by IR, ¹H NMR, ¹³C NMR, Fab mass spectrometry and their purities were confirmed by elemental analyses. In vitro antibacterial activity of these compounds were evaluated by the disk diffusion assay and then the minimum inhibitory concentration (MIC) strain of two Gram-positive and two Gram-negative bacteria like Aeromonas hydrophila, Yersinia enterocolitica, Listeria monocytogenes, and Staphylococcus aureus, among all the compounds, alkoxy [5-(furan-2-yl)-2-(benzyloxy)phenyl]-4,5-dihydro-1H-pyrazole-1-carbothioamide 2b and 5-(furan-2-yl)-1-[2-(naphthalen-2-ylmethoxy) phenyl]-4,5-dihydro-1H-pyrazole-1-carbothioamide 2d showed the most promising antibacterial agent when compared to gentamicin and tetracycline.     

Cyclocondensation of n-(prop-2-yn-1-yl)- and n-(penta-2,4-diyn-1-yl)- <Emphasis Type="Italic">o</Emphasis>-phenylenediamines with phenyl isothiocyanate and carbon disulfide

The cyclocondensation of N-(prop-2-yn-1-yl)-o-phenylenediamines with phenyl isothiocyanate leads to the formation of 1-(prop-2-yn-1-yl)-1,3-dihydro-2H-benzimidazole-2-thiones irrespective of the substituent nature at the triple bond. Reactions of both mono- and diacetylenic derivatives of o-phenylenediamine with carbon disulfide in the presence of KOH proceed with the formation of two heterocyclic nuclei simultaneously. From N-(prop-2-yn-1-yl)-o-phenylenediamines containing an aryl substituent at the triple bond, and N-(penta-2,4-diyn-1-yl)-o-phenylenediamines 2-methylidene-2,3-dihydro[1,3]thiazolo[3,2-a]benzimidazoles are formed. The latter are readily isomerized under the action of base giving thiazolo[3,2-a]benzimidazoles. The cyclocondensation of N-(alk-2-yn-1-yl)-o-phenylenediamines with CS₂ leads to [1,3]thiazino[3,2-a]benzimidazoles.     

The synthesis and characterisation of N-(1-carbamoyl-1,1-dialkyl-methyl)-(S)-prolinamides and related pyrrolidin-2-yl-4,5-dihydro-1H-imidazol-5-ones as potential enantioselective organocatalysts

The acylation of substituted 2-aminopropanamides with (2S)-Boc-proline, (2S)-Cbz-proline and (2S)-Bn-proline was used to prepare substituted 1-protected N-(1-carbamoyl-1,1-dialkyl-methyl)-(S)-prolinamides (74-89%), whose subsequent deprotection gave N-(1-carbamoyl-1,1-dialkyl-methyl)-(S)-prolinamides (94-95%). The enantiomerically pure N-(1-carbamoyl-1,1-dialkyl-methyl)-(S)-prolinamides obtained were tested as organocatalysts for the aldol reaction of cyclohexanone with 4-nitrobenzaldehyde, with yields ranging from 38% to 79% ee. The highest enantioselectivity (89% ee) was achieved by catalysis with N-(1-carbamoyl-cyclopentyl)-(S)-prolinamide (methanol, l0% HCl). By the action of sodium methoxide, Boc-N-(1-carbamoyl-cyclopentyl)-(S)-prolinamide was quantitatively cyclised to 2-(1-Boc-pyrrolidin-2-yl)-1,3-diazaspiro[4.4]non-1-en-4-one, which was accompanied by racemisation at the stereogenic centre of the proline skeleton. Alternatively, the substituted 4,4-dialkyl-2-pyrrolidin-2-yl-4,5-dihydro-1H-imidazol-5-ones were prepared by oxidation of 4,4-dialkyl-2-((2S)-1-Boc-pyrrolidin-2-yl)-4,5-dihydro-1H-imidazolidin-5-ones (54-69%). In an acid medium, 2-pyrrolidin-2-yl-1,3-diazaspiro[4.4]non-1-en-4-one and (4S)-4-isopropyl-4-methyl-2-pyrrolidin-2-yl-4,5-dihydro-1H-imidazol-5-one underwent racemisation. Conversely, the free base of (2S)-2-pyrrolidin-2-yl-1,3-diazaspiro[4.4]non-1-en-4-one very easily underwent oxidation to give the achiral 2-(4,5-dihydro-3H-pyrrol-2-yl)-1,3-diazaspiro[4.4]non-1-en-4-one.     

Synthesis,characterization and anticancer evaluation of 2-(naphthalen-1-ylmethyl/naphthalen-2-yloxymethyl)-1-[5-(substituted phenyl)-[1,3,4]oxadiazol-2-ylmethyl]-1H-benzimidazole

In the present study o-phenylenediamine and naphtene-1-acetic acid/2-naphthoxyacetic acid were used as a starting material through a series of steps and 2-(naphthalen-1-ylmethyl/Naphthalen-2-yloxymethyl)-1H-benzimidazol-1-yl]acetohydrazide 5a, 5b were obtained. In the first series 1,3,4-oxadiazole derivatives have been synthesized from Schiff base of the corresponding hydrazide i.e. 2-[2-(naphthalen-1-ylmethyl)-1H-benzimidazol-1-yl]acetohydrazide 5a by using Chloramin-T. In the second series 1,3,4-oxadiazole has been synthesized from 2-{2-[(naphthalen-2-yloxy)methyl]-1Hbenzimidazol-1-yl}acetohydrazide 5b by using phosphorous oxychloride and aromatic acid. These compounds were evaluated by IR, NMR, Mass spectrometry, elemental analysis and finally in vitro anticancer evaluation was carried out by NCI 60 Cell screen at a single high dose (10–5 M) on various panel/cell lines. One compound 7c was found to be the most active on breast cancer cell line and compounds 4b and 7d were moderately active.