Volume 21, Issue 4

Montmorillonite K10 is a suitable catalyst in a multicomponent reaction involving an aldehyde, an amine, and thioglycolic acid in N , N -dimethylformamide as solvent at moderate (50°C) to reasonably high (120°C) temperatures to form thiazolidinones. The reaction involves easy workup and purification. Several thiazolidinones were prepared. In particular, campholenic aldehyde obtained from α-pinene was used to synthesize potentially bioactive thiazolidinones. All products were characterized by IR, 1 H NMR, and mass spectra. Preliminary anticancer screening tests revealed that two compounds show anticancer activity and can be taken up for further screening.

An efficient synthesis of new pyrrolopyrimidinones 3a-d and isoxazolopyrimidinones 4a-c from the respective aminocyanopyrroles 1a-d and aminocyanoisoxazoles 2a-c is presented. The synthesized compounds were screened for antimicrobial activity against a panel of bacteria and fungi. Compound 4c exhibits remarkable activity against a broad spectrum of Gram-positive and Gram-negative bacteria and pathogenic fungi.

Reaction of 2-hydrazinoquinazolin-4(3 H )-ones with acetylacetone results in the formation of 1-methyl[1,2,4]triazolo[4,3- a ]quinazolin-5(4 H )-ones instead of 2-(3,5-dimethyl-1 H -pyrazol-1-yl)quinazolin-4(3 H )-ones. Under similar conditions, the 7-hydrazinocarbonyl group in quinazolin-4(3 H )-one moiety is transformed into a pyrazole derivative, which can be replaced by amine with the amide formation.

New 4′-( N -alkylpyrrol-2-yl)-2,2′:6′,2″-terpyridines were synthesized by N -alkylation of a pyrrole substituent with alkyl halides in dimethyl sulfoxide.

5-Methyl-3-(bromomethyl)pyridine is the key intermediate in the synthesis of rupatadine. In this article, a new preparation of 5-methyl-3-(bromomethyl)pyridine hydrobromide is reported, which used 5-methylnicotinic acid as the starting material, with a 65.9% overall yield. This method has the merits of being simple, efficient and environmentally friendly.

A green and simple method for the synthesis of the title compounds 4 by the reaction of 5-chloroacetyl-8-hydroxyquinoline ( 1 ), pentane-2,4-dione ( 2 ), and amines 3 in the presence of a catalytic amount of 1,4-diazabicyclo[2.2.2]octane at 60°C is described. The procedure is amenable for the synthesis of other substituted pyrroles. Short reaction time, environmentally friendly procedure, and excellent yields are the main advantages. The structures of products 4a–n were characterized by 1 H NMR, IR, and MS spectra.

A new fluorescent sensor based on a benzimidazole unit bearing bis(ethoxycarbonylmethyl)amino groups was designed and synthesized. The ligand exhibits strong sensitivity and selectivity for Ag + by enhanced fluorescent intensity in the presence of a wide range of other tested metal ions in methanol. The colorimetric and fluorescent response to Ag + can be conveniently detected even by the naked eye, which offers a facile method for visual detection of Ag + .

New 10 H -benzo[ b ]pyridazino[3,4- e ][1,4]thiazines were prepared and evaluated for inhibitory activity against soybean 15-lipoxygenase enzyme. These compounds were synthesized by the sequential treatment of 4-bromo-3,6-dichloropyridazine with 2-aminothiophenol and a secondary amine with the subsequent heterocyclization in the presence of sodium amide.

New 3-aryl-pyrido[2,1- b ][1,3]benzothiazole derivatives 2a – e were synthesized in excellent yields via the reaction of benzothiazoleacetonitrile ( 1 ) with different aromatic aldehydes. The treatment of 2-(benzo[ d ]thiazol-2-yl)-3-(pyridin-4-yl)acrylonitrile ( 6 ) with malononitrile afforded 1-amino-3-(pyridin-4-yl)-3 H -pyrido[2,1- b ][1,3]benzothiazole-2,4-dicarbonitrile ( 7 ), which was allowed to react with a variety of reagents to provide pyrimido[5′,4′:5,6]pyrido[2,1- b ][1,3]benzothiazole 8 , 9 and [1,3]benzothiazolo[3,2- a ][1,8]naphthyridine 10 , 15 derivatives. All synthesized products were confirmed by elemental analysis, IR, 1 H-NMR, 13 C-NMR, and mass spectral data.

A route to 3-benzylidene-dihydrofurochromen-2-ones from 2 H -chromenes is described. Lactonization of 2 H -chromenes was achieved using a two-step cyclopropanation-rearrangement sequence. Subsequent conversion of these intermediates to the corresponding α-benzylidene lactones was achieved by lithium enolate aldol reaction, followed by base-promoted elimination of the aldolate mesylates. The alkene geometry was found to be base-dependent. While the use of KOBu t favored formation of the E isomer, the application of DBU showed a slight preference for the Z isomer. In further studies, these 3-benzylidene-dihydrofurochromen-2-ones were converted to polyaromatic structures possessing all the required functionality for biflavonoid synthesis.

A series of piperazine- and cyclen-conjugated dehydroabietylamine derivatives were synthesized and characterized by 1 H NMR, 13 C NMR, and HRMS. The in vitro antitumor activities of conjugates 10 – 13 against MCF-7 and HepG-2 tumor cell lines were evaluated using CCK-8 assay. The results show that the synthesized compounds cause a dose-dependent inhibition of cell proliferation and display different antitumor activities with the IC 50 values ranging from 23.56 to 78.92 μ m . Moreover, the antitumor activity of conjugate 10 against the MCF-7 cell line is superior to that of the positive control 5-fluorouracil. In addition, flow cytometric assay revealed that the representative conjugate 10 could induce apoptosis in MCF-7 tumor cells in a dose-dependent manner.

Novel spiro derivatives of piperidone 4a–f were synthesized, characterized, and screened against a panel of different bacterial and fungal strains. The study revealed the potential of these molecules for further development as antimicrobial agents.