POCl3-mediated synthesis of 2-substituted benzimidazolyl-coumarin,benzimidazolyl-indole,and styrylbenzimidazole derivatives

2-Substituted benzimidazolyl heterocycles and styrylbenzimidazoles have been synthesized by the reaction of substituted o-phenylenediamine with different heterocyclic carboxylic acids and cinnamic acid respectively in the presence of POCl₃ as a solvent and catalyst. The proposed reaction has advantageous features of good yields, short reaction times, and operational simplicity. In addition, the scope and limitations were explored, and a plausible reaction mechanism was proposed. The synthesized molecules were characterized by infrared, ¹H NMR, ¹³C NMR, and mass spectral data. Further, single crystals of 2-(1H-indol-2-yl)-1H-benzo[d]imidazole have been developed and structural parameters were collected from x-ray diffraction data.     

New Synthetic Approaches to Substituted Pyridine-2-(1H)-ones Clubbed with Substituted Aryl Diazo Substituents

6-Triazolylpyridone derivatives were synthesized by coupling 4-(4-methoxyphenyl)-6-(1H-1,2,4-triazol-1-yl)-1-(3-chlorophenyl)pyridin-2(1H)-one with substituted benzenediazonium chlorides in the form of two isomers, which were separated by column chromatography and characterized by ¹H and ¹³C NMR. Following the green approach, solvents were avoided as much as possible. The reaction monitoring was carried out by gas chromatography as well as thin-layer chromatography. The scope and limitation of the method are discussed. The structures of all the compounds have been assigned unambiguously on the basis of elemental analysis, infrared, and NMR spectral data and have been evaluated for antimicrobial and antitubercular activities.     

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 and antimicrobial activity of novel quinazolinone–thiazolidine–quinoline compounds

A series of 2-(2-chloroquinolin-3-yl)-5-((aryl)benzylidene)-3-(4-oxo-2-phenylquinazolin-3(4H)-yl)thiazolidin-4-ones (V)_1–12 have been synthesized. In order to establish optimization of different parameters of chemical transformation, that is the reaction pathway for each step and reaction conditions in the each step, in the present paper, different solvents and catalysts were used. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, ¹H NMR and ¹³C NMR spectral data. All the newly synthesized compounds were screened against various strains of bacteria and fungi.     

Synthesis of Ethyl 2‐Amino‐4‐benzoyl‐5‐oxo‐5,6‐dihydro‐4H‐pyrano[3,2‐c]quinoline‐3‐carboxylates by a One‐pot,Three‐Component Reaction in the Presence of TPAB

In this research, in order to synthesize a series of ethyl 2‐amino‐4‐benzoyl‐5‐oxo‐5,6‐dihydro‐4H‐pyrano[3,2‐c]quinoline‐3‐carboxylates, a green and an efficient method is proposed through one‐pot three‐component reaction of substituted arylglyoxals, ethyl cyanoacetate, and 4‐hydroxyquinolin‐2(1H)‐one in the presence of terapropylammonium bromide as a catalyst in good yields. All synthesized new substances were characterized by FTIR, ¹H‐NMR, and ¹³C‐NMR spectral data and elemental analysis.     

Synthesis and characterization of novel benzoxazine-based arylidinyl succinimide derivatives

1,4-Benzoxazine skeleton holds substantial promise for further exploration owing to its immense pharmacological potential. In this pursuit, a series of 20 novel benzoxazine-based arylidinyl succinimide derivatives (23–42) were synthesized in moderate to good yields by the reaction of ethyl 2-(7-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl)acetate (22) with various aromatic aldehydes under Wittig reaction conditions in the presence of triphenylphosphine and ethanol. All these synthesized compounds were fully characterized from their spectral data (¹H, ¹³C, and ²D NMR, IR, UV, high-resolution mass spectroscopy (HRMS)) and further confirmed by X-ray crystallographic analysis of a representative compound (32). Antibacterial activity of obtained arylidinyl succinimide derivatives was evaluated against both Gram-positive and Gram-negative bacterial strains and were found to exhibit insignificant activity as compared to the reference.     

Bis coumarinyl bis triazolothiadiazinyl ethane derivatives: Synthesis,antiviral activity evaluation,and molecular docking studies

A series of novel 3,3′-(3,3′-(dihydroxy/hydroxyethane-1,2-diyl)bis(7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-6,3-diyl))bis(2H-chromen-2-ones) were prepared by the condensation of thiocarbohydrazide with tartaric acid or malic acid followed by various 3-(2-bromoacetyl)-2H-chromen-2-ones in two steps with good yields. All the synthesized compounds were characterized by analytical and spectral (IR, ¹H NMR, ¹³C NMR, and mass) data. These synthesized bis(triazolothiadiazinyl coumarin) compounds were evaluated for broad spectrum of antiviral activity. Among all the tested compounds, compound 5f exhibited antiviral activity against H1N1 virus. The molecular docking studies of these compounds against H1N1 neuraminidase enzyme were performed. The binding affinity and binding values were compared with standard drugs.     

The synthesis and characterization of three new vic -dioximes and their nickel(II), copper(II) and cobalt(II) complexes

Three new vic-dioximes, [L¹H₂], N-(4-ethylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, [L²H₂], N-(4-butylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, and [L³H₂], N-(4-methoxyphenyl)amino-1-acetyl-1-cyclohexenylglyoxime were synthesized from 1-acetyl-1-cyclohexeneglyoxime and the corresponding substituted aromatic amines. Metal complexes of these ligands were also synthesized with Ni(II), Cu(II), and Co(II) salts. These new compounds (ligands and complexes) were characterized with FT–IR, magnetic susceptibility measurement, molar conductivity measurements, mass spectrometry measurements, thermal methods (e.g. thermal gravimetric analysis), ¹H NMR (Nuclear Magnetic Resonance) and ¹³C NMR spectral data and elemental analyses.     

1H and 13C NMR spectral assignments of novel chromenylchalcones

Several types of chalcones containing 2H‐chromen group were synthesized. Claisen–Schmidt condensation of 2H‐chromen‐3‐carbaldehydes (I) with methoxy substituted acetophenones afforded (E)‐3‐(2H‐chromen‐3‐yl)‐1‐(methoxyphenyl)prop‐2‐en‐1‐ones (chromenylchalcones, 1–7). Other types of chromenylchalcone, (E)‐1‐(6‐methoxy‐2H‐chromen‐3‐yl)‐3‐(methoxyphenyl)prop‐2‐en‐1‐ones (8–13) were also obtained between reaction of methoxy substituted benzaldehydes and 1‐(6‐methoxy‐2H‐chromen‐3‐yl)ethanone (II). Dichromenylchalcones (14–16) were also synthesized through the same reaction between aldehydes (I) and ketone (II). Their complete ¹H‐NMR and ¹³C‐NMR assignments are reported here and more polysubstituted chromenylchalcones synthesized or isolated from the natural sources in the future can be identified on the basis of the NMR data reported here. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis,Characterization, and In Vitro Microbial Evaluation of Some New 4H‐Chromene and Quinoline Derivatives of 1H‐Pyrazole

A new series of nine derivatives of 4H‐pyrano[3,2‐c]chromene and 12 derivatives of N‐thiazolyl‐4H‐quinoline of 1H‐pyrazole has been synthesized by one pot base catalyzed cyclocondensation reaction of 1H‐pyrazole‐4‐carbaldehyde, malononitrile, and 4‐hydroxy coumarin or β‐enaminones, respectively. All the synthesized compounds were characterized by elemental analysis, FT‐IR, ¹H NMR, ¹³C NMR spectral data and were further screened, against a panel of pathogenic strains of bacteria and fungi.     

Synthesis and biological activity of novel 4- and 6-(1-alkyl/aryl-1H-benzimidazol-2-yl)benzene-1,3-diols

Abstract  

A one-pot synthesis of new biologically active 4- and 6-(1-alkyl/aryl-1H-benzimidazol-2-yl)benzene-1,3-diols has been developed. The compounds were obtained by the reaction of aryl-modified sulfinylbis[(2,4-dihydroxyphenyl)methanethione] with N-substituted benzene-1,2-diamines. Elemental analysis, IR, ¹H NMR, ¹³C NMR, and mass spectral data were used to elucidate their structures. The developed method offers short reaction times, easy and quick isolation of the products, and good yields. The antiproliferative properties of the synthesized compounds were investigated against a panel of human cancer cell lines. Some of the tested compounds showed significant cytotoxic activity.     

Complexes of some 4f metal ions of the mesogenic Schiff-base,N,N′-di-(4-decyloxysalicylidene)-1′,3′-diaminobenzene: synthesis and spectral studies

A mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′,3′-diaminobenzene, H₂ddsdbz (abbreviated as H₂L), that exhibits a nematic mesophase was synthesized and its structure was studied by elemental analysis, mass spectrometry, NMR, and IR spectral techniques. The Schiff-base, H₂L, upon condensation with hydrated lanthanide(III) nitrates yields Ln^III complexes, [Ln₂(LH₂)₃(NO₃)₄](NO₃)₂, where Ln?=?La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho. Analyses of the IR and NMR spectral data imply bidentate Schiff-base through two phenolate oxygen atoms in its zwitterionic form to Ln^III, rendering the overall geometry of the complexes as a seven-coordinate polyhedron – possibly distorted mono-capped octahedron. Polarizing optical microscope and differential scanning calorimetry studies reveal that despite H₂L being mesogenic, none of the Ln^III complexes synthesized under this study exhibits mesomorphism.     

Synthesis and antimicrobial activity of some novel benzofuran based 1,2,3-triazoles

In the present study, a series of novel {6-[(1H-1,2,3-triazol-4-yl)methoxy]-3-methylbenzofuran-2-yl}(phenyl)methanones (7a–7o) have been synthesized using click chemistry approach. The structures of all newly synthesized compounds were characterized by FT-IR, ¹H and ¹³C NMR, and MASS spectral data. Most of products demonstrated high antimicrobial activity.

     

Synthesis, characterization and electrochemical investigation of a novel vic-dioxime ligand and its some transition metal complexes

4-(Chloroacetyl)diphenyl ether was synthesized from chloroacetyl chloride and diphenyl ether in the presence of AlCl₃ as catalyst in a Friedel-Crafts reaction. Then, its keto oxime and dioxime derivatives were prepared. 4-phenoxy-(N-4-chlorophenylamino)phenylglyoxime (H₂L) was synthesized from 4-(phenoxy)chlorophenylglyoxime and 4-chloroaniline. Ni(II), Co(II) and Cu(II) complexes of H₂L were obtained. The mononuclear Ni(II), Co(II) and Cu(II) complexes of H₂L have a metal–ligand ratio of 1:2 and the ligand coordinates through the two N atoms, as do most of the vic-dioximes. The structure of the ligand was identified by FT-IR, ¹H NMR, ¹³C NMR, ¹³C NMR (APT) spectroscopy and elemental analysis data. The structures of the complexes were characterized on the basis of FT-IR, ICP-AES, UV-Vis, elemental analysis, magnetic susceptibility measurements, and cyclic voltammetry. The electrochemical measurements were obtained by using cyclic voltammetry in DMF solution at room temperature. The electrochemical behaviors of H₂L and its complexes showed that the redox process of H₂L has one irreversible oxidation wave, whereas the redox processes of the complexes have both oxidation and reduction waves with metal centered.     

Synthesis and Antifungal Activity of Novel Quinazolin-4(3H)-one Derivatives

A novel group of 6-iodoquinazolin-4(3H)-one derivatives was prepared starting from 6-iodo-2-ethoxy-4H-3,1-benzoxazin-4-one (3) via action of various nitrogen nucleophiles such as primary and secondary amines, hydrazine hydrate, and its derivatives. The 3-amino-2-hydrazinyl-6-iodoquinazolin-4(3H)-one (15) was used as a key starting material to prepare new heterocyclic compounds. The structures of all synthesized compounds were inferred from the infrared, mass spectral, and ¹H NMR spectral data as well as elemental analysis. The fungicidal activities of the target compounds were preliminarily evaluated.     

Green Synthesis of 1‐(1,2,4‐Triazol‐4‐yl)spiro[azetidine‐2,3′‐(3H)indole]‐2′,4′(1′H)‐diones as Potential Insecticidal Agents

One pot green synthesis of 1‐(1,2,4‐triazol‐4‐yl)spiro[azetidine‐2,3′‐(3H)‐indole]‐2′,4′(1′H)‐diones was carried out by the reaction of indole‐2,3‐diones,4‐amino‐4H‐1,2,4‐triazole and acetyl chloride/chloroacetyl chloride in ionic liquid [bmim]PF₆ with/without using a catalyst. It was also prepared by conventional method via Schiff's bases, 3‐[4H‐1,2,4‐triazol‐4‐yl]imino‐indol‐2‐one. Further, the corresponding phenoxy derivatives were obtained by the reaction of chloro group attached to azetidine ring with phenols. The synthesized compounds were characterized by analytical and spectral (IR, ¹H NMR, ¹³C NMR, and FAB mass) data. Evaluation for insecticidal activity against Periplaneta americana exhibited promising results.     

An Efficient Synthesis of Some Novel 3‐Cyano‐4‐imino‐2‐(methylthio)4H‐pyrido[1,2‐a]pyrimidine and Their Derivatives

Pyrazolo pyrimido pyrimidine ( 4a–k ) was prepared by the reaction of compound 3‐cyano‐4‐imino‐2‐(methylthio)4H‐pyrido[1,2‐a]pyrimidine ( 3 ) with hydrazine hydrate, phenyl hydrazine, 2‐hydrazino benzothiazole, and 6‐substituted hydrazine benzothiazole in N,N‐dimethylformamide and anhydrous potassium carbonate. These synthesized compounds were characterized by elemental analysis IR, ¹H NMR, and mass spectral data.     

Synthesis and characterization of mono- and bicyclic heterocyclic derivatives containing 1,2,4-triazole, 1,3,4-thia-, and -oxadiazole rings

A series of new N- and S-substituted 1,3,4-oxadiazole derivatives were synthesized. 5-Pyridin-3-yl-3-[2-(5-thioxo-4,5-dihydro-l,3,4-thiadiazol-2-yl)ethyl]-1,3,4-oxadiazole-2(3H)-thione and 5-[(5-(pyridin-3-yl)-1,3,4-oxadiazol-2-ylthio)methyl]-N-phenyl-1,3,4-thiadiazol-2-amine were formed by cyclization of 3-(5-pyridin-3-yl-2-thioxo-1,3,4-oxadiazol-3(2H)-ylpropanimidohydrazide and 2-[(5-pyridin-3-yl-1,3,4-oxadiazol-2-yl)thio]thiosemicarbazide with CS₂ and H₂SO₄. On the other hand, a number of new bicyclic 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives were synthesized. 6-Pyridin-3-ylbis[1,2,4]‐triazolo[3,4-b:4′,3′-d][1,3,4]thiadiazole-3(2H)-thione was synthesized by reaction of 6-(hydrazino)-3-pyridine-3-yl[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole with CS₂/KOH/EtOH. The structures of the newly synthesized compounds were elucidated by the spectral and analytical data IR, Mass, and ¹H NMR spectra. Correspondence: Adel A.-H. Abdel-Rahman, Department of Chemistry, Faculty of Science, Menoufia University, Shebin El-Koam, Egypt; Wael A. El-Sayed, National Research Centre, Department of Photochemistry, Cairo, Egypt.     

Synthesis of New Pyrimido[4′,5′:3,4]pyrazolo[1,2‐b]phthalazine‐4,7,12‐triones: Derivatives of a New Heterocyclic Ring System

Several derivatives of the new pyrimido[4′,5′:3,4]pyrazolo[1,2‐b]phthalazine‐4,7,12‐trione ring system have been prepared by the reaction of 3‐amino‐1‐aryl‐5,10‐dioxo‐5,10‐dihydro‐1H‐pyrazolo[1,2‐b]phthalazine‐2‐carbonitriles with aliphatic carboxylic acids in the presence of phosphoryl chloride (POCl₃). The synthesized compounds were characterized on the basis of IR, ¹H NMR, and ¹³C NMR spectral and microanalytical data.     

Synthesis of a Novel Series of 2,3‐Disubstituted Quinazolin‐4(3H)‐ones as a Product of a Nucleophilic Attack at C(2) of the Corresponding 4H‐3,1‐Benzoxazin‐4‐one

A new series of 2,3‐disubstituted quinazolin‐4(3H)‐one derivatives was synthesized by nucleophilic attack at C(2) of the corresponding key starting material 2‐propyl‐4H‐3,1‐benzoxazin‐4‐one (Scheme 2). The reaction proceeded via amidinium salt formation (Scheme 3) rather than via an N‐acylanthranilimide. The structure of the prepared compounds were elucidated by physical and spectral data like FT‐IR, ¹H‐NMR, and mass spectroscopy.