Synthesis and Analgesic Activity of Some 1-Benzofurans, 1-Benzothiophenes and Indoles

Synthesis of Cytotoxic Benzofurans and Ethers Derivatives of Paeonol

Paeonol is a broadly studied natural product due to its many biological activities. Using a methodology previously employed by our research group, 11 derivatives of paeonol were synthesized (seven of them are unpublished compounds), including four ethers and seven benzofurans. Additionally, we determined the crystal structure of one of these ether derivatives (1 a) and of five benzofuran derivatives (2 a, 2 b, 2 c, 2 f and 2 g) by single crystal X-ray diffraction. To continue studying the cytotoxicity of this natural product and its derivatives, all compounds were tested against two cancer cell lines, HCT116 and MCF-7. Compounds 2 b, 2 e, and 2 g were considered active against the colorectal adenocarcinoma cells HCT116 (Growth inhibition >60 %). Compound 2 e showed an IC50 of 0.2 μM and was selected for further analysis, results reinforce its anticancer potential.

Palladium(0)-catalyzed single and double isonitrile insertion: a facile synthesis of benzofurans, indoles, and isatins

A palladium(0)-catalyzed cascade process consisting of isonitrile insertion and α-Csp(3)-H cross-coupling can be achieved for the synthesis of benzofurans and indoles. The construction of isatins by a Pd-catalyzed cascade reaction incorporating double isonitrile insertion, amination, and hydrolysis has also been achieved. The key features of this work include diverse heterocycle synthesis, phosphine-ligand-free reaction conditions, a one-pot procedure, simple and commercially available starting materials, broad functional-group compatibility, and moderate to good reaction yields.

Synthesis and preliminary biological evaluation of new anti-tubulin agents containing different benzoheterocycles

A new series of compounds, in which the 2-amino-4-methoxyphenyl ring of phenstatin analogue 5 was replaced with 2- or 3-amino-benzoheterocycles, was synthesized and evaluated for antiproliferative activity and inhibition of colchicine binding. The lack of activity of 3',4'-dimethoxy- and 4'-methoxy-benzoyl derivatives (8 and 9, respectively) indicates that the 3',4',5'-trimethoxybenzoyl moiety is critical for the activity. Two compounds, 7 and 11, displayed potent antiproliferative activity, with IC50 values ranging from 25 to 100 nM against a variety of cancer cell lines. Derivative 11 was more active than CA-4 as an inhibitor of tubulin polymerization. The results demonstrated that the antiproliferative activity was correlated with inhibition of tubulin polymerization.

Syntheses of 3-acetoacetylaminobenzo[b]furan derivatives having cysteinyl leukotriene 2 receptor antagonistic activity

Novel 3-acetoacetylaminobenzo[b]furan derivatives having a modified triene system at the 3-position were synthesized starting with 3-aminobenzo[b]furans. The enol isomers, 3-[(3-hydroxybut-2-enonyl)amino]benzo[b]furans (), of the 3-acetoacetylaminobenzo[b]furans were obtained as stable isomers owing to formation of a hydrogen bonding between the enol hydroxyl group and the amidocarbonyl group. The planarity of the C-2 substituent through the C-3 side chain suggested the existence of a modified conjugational triene system in the enol compound. Cysteinyl leukotriene 1 and 2 receptor antagonistic activities for these compounds were evaluated. 2-(4-Cyanobenzoyl or ethoxycarbonyl)-3-[(2-cyano-3-hydroxybut-2-enonyl)amino]benzo[b]furans (, ) were moderately active.

Combinatorial synthesis of libraries of indole derivatives

The synthesis of two indole derivative libraries is described. 2-Acyl-3-amino-indoles 4 can easily be accessed by treatment of the intermediates 3 with bases in a one-pot reaction sequence whereas the reaction of the isolated intermediates 5 (R(3)=aromatic-, heteroaromatic, or cycloalkyl) with acid chlorides yielded the novel indole derivatives 6. The products were purified by reversed phase column chromatography and obtained in multi-milligram quantities in acceptable yields.

Synthesis and Analgesic Activity of Some Substituted 1-Benzofurans and 1-Benzothiophenes

2-Benzoyl- and 2-(pyridylcarbonyl)-1-benzofuran-3-amines were prepared from 2-hydroxybenzonitrile and corresponding bromoethanone derivatives. 2-Benzoyl- and 2-(pyridylcarbonyl)-1-benzothiophene-3-amines were prepared analogously from 2-sulfanylbenzonitrile. 2-Benzoyl-1-benzofuran-3-amine treated with acetic anhydride or ethyl chloroformate provided the corresponding N-acetyl or N-ethoxycarbonyl derivatives. These N-activated compounds were alkylated with ethyl bromoacetate to provide ethyl N-acetyl-N-(2-benzoyl-1-benzofuran-3-yl)glycinate and ethyl N-(2-benzoyl-1-benzofuran-3-yl)-N-ethoxycarbonylglycinate, respectively. Their mild hydrolysis gave the corresponding glycine derivatives. Methylation of ethyl N-(2-benzoyl-1-benzofuran-3-yl)carbamate gave the corresponding N-methyl carbamate, which was hydrolyzed to N-methyl-(2-benzoyl-1-benzofuran-3-yl)amine. 2-Benzoyl-7-methoxy-1-benzofuran-3-amine and 2-(4-methoxybenzoyl)-1-benzofuran-3-amine were demethylated with boron tribromide to the corresponding hydroxy derivatives; their O-alkylation with ethyl bromoacetate than gave ethyl [(3-amino-2-benzoyl-1-benzofuran-7-yl)oxy]acetate and ethyl {4-[(3-amino-1-benzofuran-2-yl)carbonyl]phenoxy}acetate, respectively. The mild hydrolysis of these esters provided corresponding acids. Similarly, alkylation of the hydroxy derivatives with (dimethylamino)propyl chloride gave corresponding (dimethylamino)propoxy derivatives. 2-Hydroxybenzonitrile treated with 2-bromo-1-(2-, 3-, or 4-pyridyl)ethan-1-one provided the respective 2-(pyridylcarbonyl)-1-benzofuran-3-amine. Similar 2-(pyridylcarbonyl)-1-benzothiophene-3-amines were prepared analogously from 2-sulfanylbenzonitrile. 2-Benzoyl-3-(bromomethyl)-1-benzofuran treated with dimethylamine, 1-methylpiperazine, and sodium 1-methylpiperidine-4-thiolate gave the corresponding alkylation products. Several compounds were found to exhibit considerable analgesic activity.