Multi-step polymer-assisted solution-phase (PASP) library synthesis of functionalized diaminobenzamides

A parallel solution-phase library synthesis of functionalized diaminobenzamides is described. The four-step library synthesis is accomplished using polymer-assisted solution-phase (PASP) synthesis techniques. This high-yielding, multi-step sequence utilizes sequestering resins for the removal of reactants, reactant by-products, and employs a resin capture/release strategy as a key library synthesis step. Step one of the sequence relies on the displacement of an activated fluoro-group from the aromatic ring of 1a, b with a variety of primary amines to introduce the first diversity position. Step two is hydrolysis of the benzoate ester to a benzoic acid which is subsequently captured on a polyamine resin, washed, and released to give 4a, b in pure form. Step three utilizes PASP resins to mediate the amide coupling of a benzoic acid with a variety of primary amines to give the aminonitrobenzamides 5a, b and introduces the second diversity position. Step four is the parallel reduction of the aminonitrobenzamides 5a, b to the functionalized diaminobenzamides 6a, b. This library synthesis proceeds with high overall purities which average 80 % over the 4-step sequence.     

A novel phase-switching protecting group for multi-step parallel solution phase synthesis

A new phase-tag 1 which facilitates the parallel solution phase synthesis of carboxylic acids, esters, and carboxamides is reported. The new phase tag assists compound purification by enabling the selective resin capture of reaction products in either a reversible pH dependent manner (solid-phase extraction), or irreversibly in a Diels-Alder reaction.     

Multistep parallel synthesis of substituted 5-aminobenzimidazoles in solution phase

An efficient solution-phase parallel synthesis of multisubstituted 5-aminobenzimidazoles is described. The two fluorine atoms of 1,5-difluoro-2,4-dinitrobenzene (DFDNB) are sequentially and quantitatively replaced by nucleophiles. Simultaneous reduction of aromatic m-dinitro groups by Pd-C/HCOONH(4) results in 2,4,5-benzenetriamines, which are continuously condensed with aldehydes to successfully construct the benzimidazole ring without additional oxidants. The free aromatic amino group is further modified by anhydrides, isocyanates, isothiocyanates, and sulfonyl chlorides. All the reactions involved here are highly effective in giving the desired products at room temperature. Four diversity points are introduced in the final products.     

Polymer-assisted, multi-step solution phase synthesis and biological screening of histone deacetylase inhibitors

The polymer-assisted solution phase synthesis (PASP) of an array of histone deacetylase (HDAc) inhibitors is described. HDAc inhibitors have considerable potential as new anti-proliferative agents. Selected compounds were shown to inhibit both human endothelial cell proliferation, and the formation of tubules (neovascularisation) in an in vitro model of angiogenesis.     

Efficient solution phase parallel synthesis of norstatine analogs

The reaction of glycidic amides with various functionalized nitriles to afford norstatine analogs in a regio- and diastereoselective fashion (43-99% yield) is described. Utilizing this chemistry, a 20 membered solution phase library was prepared in two steps featuring three points of diversity.     

苯并咪唑衍生物的微波辅助合成研究

开展了邻苯二胺与4-甲基苯甲醛、4-硝基苯甲醛及4-二甲氨基苯甲醛反应生成苯并咪唑衍生物的微波辅助合成研究。用高效液相色谱法(HPLC)测定其产率。结果表明:相同反应时间,在微波辅助条件下,生成苯并咪唑衍生物的反应产率均较常规加热条件下增大,并且芳醛对位上取代基吸电子能力越强,反应产率越高。     

Rapid microwave-assisted solution phase synthesis of substituted 2-pyridone libraries

2-Pyridone and 2-quinolone analogues are well-known biologically active heterocyclic scaffolds. Libraries of 3,5,6-substituted 2-pyridone derivatives are generated by rapid microwave assisted solution phase methods using a one-pot, two-step protocol. The three-component condensation of CH-acidic carbonyl compounds, N,N-dimethylformamide dimethylacetal and methylene active nitriles, leads to 2-pyridones and fused analogues in moderate to good overall yields and high purities. The proposed mechanism of this novel multi-component reaction, structure elucidation of products and intermediates are discussed.     

Design,synthesis, antimicrobial activity and computational studies of novel azo linked substituted benzimidazole,benzoxazole and benzothiazole derivatives

Novel azo linked substituted benzimidazole, benzoxazole, and benzothiazole were synthesized by diazo coupling and characterized by ¹H NMR, elemental analysis, FTIR and UV–vis spectroscopy. The newly synthesized compounds were evaluated for invitro antibacterial activity against Staphylococcus aureus and Escherichia Coli strains by Resazurin microtiter assay method (REMA). The minimum inhibitory concentration (MIC in μg/mL) were used to express the antibacterial activities. The azo linked compounds exhibited good to moderate or high antibacterial activities in vitro. Computational studies were performed to correlate HOMO-LUMO gap with antibacterial activity. The comparative molecular docking studies revealed better insights into binding mechanisms.     

Synthesis of substituted derivatives of imidazo [5, 1-b] benzimidazole

Heating, either molten or in high-boiling solvents, 1-methyl-2-[(N-phenylthiocarbamoyl)amino] (pyrid-4-yl)-methylbenzimidazole, or refluxing with phosphorus oxychloride in benzene acyl derivatives of 1-methyl-2-[(pyrid-4-yl)(amino)]- and 1-methyl-2 [(phenyl)(amino)]-methylbenzimidazoles, gives the corresponding derivatives of the imidazo [5, 1-b] benzimidazole system, hitherto undescribed in the literature.     

Solution-phase parallel synthesis of substituted benzimidazoles

A solution-phase parallel synthesis of o-phenylenediamines is described. These intermediates were then subsequently converted to benzimidazole scaffolds (three-point diversity) in excellent purities and yields. High-throughput purification of this multistep synthetic sequence was accomplished using polymer-bound scavengers and reagents and liquid-liquid extraction protocols.     

Synthesis and spectral-luminescence properties of 2-(2′-tosylaminophenyl)benzimidazole and its substituted derivatives

Tosylamino-substituted 2-arylbenzimidazoles have blue or green fluorescence in the crystalline state and in toluene at room temperature. The effect of the substituents on the position of the absorption and fluorescence bands and on the strength of the intramolecular hydrogen bond was investigated. An anomalously large Stokesian shift within the limits 8800–11450 cm^¡1 is characteristic for compounds that contain an o-tosylamino group.     

Reversed phase liquid chromatography of some benzimidazole derivatives

Summary The retention behaviour of a series of benzimidazole derivatives has been studied as a function of the water content of aqueous methanol and aqueous acetonitrile eluents. The relationship between the retention constant (log k) and the pH of the aqueous phase was linear, with slope values depending on the composition of the aqueous phase, the molecular structure of the compound, and the type of C-18 bonded stationary phase. The type of organic modifier significantly affected the shape of the relationship between log k and the volume fraction of organic modifier in the mobile phase.     

Fully automated multi-step solution phase synthesis using polymer supported reagents: preparation of histone deacetylase inhibitors

The first fully automated multi-step polymer assisted solution phase (PASP) synthesis is described. An array of histone deacetylase (HDAc) inhibitors was prepared by an unattended 4-5 step sequence incorporating in-line 'catch and release' purification.     

N-acyl (substituted) phenylglycine derivatives

Amidoalkylation of three benzoheterocycles, benzimidazole-2-one, 1,3-dihydrobenzo[c]-thiophene 2,2-dioxide and 1,3-dihydro-2,1,3-benzothiadiazole using N-acylhippuric acids was successful. The corresponding phenylglycine analogs were prepared by removal of the N-acyl protecting group.     

Nano ceria catalyzed synthesis of substituted benzimidazole,benzothiazole, and benzoxazole in aqueous media

A series of substituted benzimidazoles, benzothiazoles, and benzoxazoles was synthesized by combining 1,2-phenylenediamine, 2-aminothiophenol, or 2-aminophenol with aryl, heteroaryl, aliphatic, α,β-unsaturated aldehydes in the presence of nano ceria (CeO₂) as an efficient heterogeneous catalyst.     

New benzimidazole derivatives: Design,synthesis, docking,and biological evaluation

The aim of this study was to synthesize novel enaminonitrile derivatives starting from 2-aminobenzimidazole and utilize this derivative for the preparation of novel heterocyclic compounds and assess their function for biological activity screening. The key precursor N-(1H-benzo[d]imidazol-2-yl)carbonohydrazonoyl dicyanide (2) was prepared in pyridine by coupling of diazotized 2-aminobenzimidazole (1) with malononitrile. Compound 2 was subjected to react with various secondary amines such as piperidine, morpholine, piperazine, diphenylamine, N-methylglucamine, and diethanolamine in boiling ethanol to give the acrylonitriles (2Z)-2-((1H-benzo[d]imidazol-2-yl)diazenyl)-3-amino-3-(piperidin-1-yl)acrylonitrile (3), (2Z)-2-((1H-benzo[d]imidazol-2-yl)diazenyl)-3-amino-3-morpholinoacrylonitrile (4), (2Z)-2-((1H-benzo[d]imidazol-2-yl)diazenyl)-3-amino-3-(piperazin-1-yl)acrylonitrile (5), (2Z)-2-((1H-benzo[d]imidazol-2-yl)diazenyl)-3-amino-3-(diphenylamino)acrylonitrile (6), (2Z)-2-((1H-benzo[d]imidazol-2-yl)diazenyl)-3-amino-3-(methyl((2S,3R,4R,5R)-2,3,4,5,6-pentahydroxyhexyl)amino)acrylonitrile (7), and (2Z)-2-((1H-benzo[d]imidazol-2-yl)diazenyl)-3-amino-3-(bis(2-hydroxyethyl)amino)acrylonitrile (8), respectively. It has been found that the behaviour of nitrile derivative 2 towards hydrazine hydrate to the creation of 4-((1H-benzo[d]imidazol-2-yl)diazenyl)-1H-pyrazole-3,5-diamine (9). The reaction of malononitrile with compound 2 in an ethanolic solution catalyzed with sodium ethoxide afforded 4-amino-1-(1H-benzo[d]imidazol-2-yl)-6-imino-1,6-dihydropyridazine-3,5-dicarbonitrile (11). Moreover, malononitrile reacted with 7 in a boiling ethanolic sodium ethoxide solution to give 2-(5-((1H-benzo[d]imidazol-2-yl)diazenyl)-4-amino-6-(methyl((2S,3R,4R,5R)-2,3,4,5,6-pentahydroxyhexyl)amino)pyrimidin-2-yl)acetonitrile (14). Heating 7 in boiling acetic anhydride and pyridine afforded (2R,3R,4R,5S)-6-(((1E)-2-((1-acetyl-1H-benzo[d]imidazol-2-yl)diazenyl)-1-(N-acetylacetamido)-2-cyanovinyl)(methyl)amino)hexane-1,2,3,4,5-pentayl pentaacetate (15). When compound 15 is heated for a long time in refluxing DMF including a catalytic of TEA, cyclization occurs to give the corresponding (2R,3R,4R,5S)-6-((1-acetyl-3-((1-acetyl-1H-benzo[d]imidazol-2-yl)diazenyl)-4-amino-6-oxo-1,6-dihydropyridin-2-yl)(methyl)amino)hexane-1,2,3,4,5-pentayl pentaacetate (16). In addition, triethyl orthoformate was reacted with compound 7 in the presence of acetic anhydride to afford the corresponding ethoxymethyleneamino derivative (2R,3R,4R,5S)-6-(((1E)-2-((1-acetyl-1H-benzo[d]imidazol-2-yl)diazenyl)-2-cyano-1-(((E) ethoxymethylene)amino)vinyl)(methyl)amino)hexane-1,2,3,4,5-pentayl pentaacetate (17). Also, it has been found that heating a mixture of 7 with DMF/DMA in anhydrous xylene yielded compound (1E)-N'-((1E)-2-((1H-benzo[d]imidazol-2-yl)diazenyl)-2-cyano-1-(methyl((2S,3R,4R,5R)-2,3,4,5,6-pentahydroxyhexyl)amino)vinyl)-N,N-dimethylformimidamide (18). In addition, compound 7, when reacted with several acid anhydrides, allowed the matching phthalimide derivatives 19–26. The results showed that compound 14 has significantly higher ABTS and antitumor activities than the other compounds. Molecular modelling was also studied for compounds 22 and 24. The viability of four many cell lines—the African green monkey kidney epithelial cells (VERO), human breast adenocarcinoma cell line (MCF-7), human lung fibroblast cell line (WI-38), and human hepatocellular liver carcinoma cell line (HepG2) was examined to determine the antitumor activities of the newly synthesized compounds. Also, it was found that compounds 9, 11, 15, 16, 22, 23, 24 and 25 are strong against HepG2 cell lines, while 16, 22, and 25 are strong against WI-38 cell lines. Moreover, it was also found that compounds 16 and 22 are strong against VERO cell lines. On the other hand, compounds 7, 14, 15, 16, and 22 are strong while the rest of the other compounds are moderate against the MCF-7 cell line. The result of docking showed that compound 24 got stabilized inside the pocket with a very promising binding score of ? 8.12 through hydrogen bonds with Arg184 and Lys179, respectively.     

Green synthesis of polycyclic benzimidazole derivatives and organic semiconductors

Polycyclic benzimidazole derivatives, an important class of compounds in organic electronics and photovoltaics, were prepared using a solvent-free "green" process based on heating carboxylic acid anhydrides and arylene diamines in the presence of zinc acetate in the solid state. Products were isolated and purified directly by train sublimation of the crude reaction mixtures. The reaction conditions were optimized using various carboxylic acid anhydrides. Optical and electrochemical properties of these materials are also described.     

New efficient route for solid-phase synthesis of benzimidazole derivatives

A simple and efficient method for the solid-phase synthesis of benzimidazole libraries is described. Monoalkylation of various o-phenylenediamines on resin-bound bromoacetamide proceeded smoothly to give the monoalkyl resin-bound o-phenylenediamines in high yields. Subsequent cyclization of the diamines with various aldehydes afforded solid-supported benzimidazoles. Cleavage from the resin gave benzimidazoles in good yields. The present method enabled the introduction of the diversity on the benzene ring of imidazoles. Azabenzimidazoles, such as 4-azabenzimidazoles, 5-azabenzimidazoles, and purines, were also synthesized in good yields with high purities by the same procedure.