Volume 22, Issue 3

One-pot condensation reaction of ethyl acetoacetate, various substituted benzaldehydes and anilines in the presence of TiCl 2 ·2H 2 O yields highly functionalized tetrahydropiperidines. Atom economy, efficiency, and short reaction times are the advantages of the method, which is carried out under mild conditions using easily accessible and inexpensive chemicals. The antimicrobial activity of the synthesized products was evaluated against three Gram-positive and three Gram-negative bacteria, a yeast and a fungus strain using disc diffusion and minimum inhibitory concentration methods.

A convenient synthesis of 1,3,4-oxadiazole containing derivatives of chromeno[4,3- b ]pyridine ( 6a–e , 8a–e and 9a–e ) starting from 4-hydroxycoumarin is presented. The synthesized compounds were screened for in vitro antimicrobial activity against representative bacterial and fungal species. The MIC (minimum inhibitory concentration) of the synthesized compounds ranges between 5 and 15 μg/mL, which is comparable with MIC of standard drugs. Compounds 6c , 8c–e , 9c and 9e have the highest potency for certain bacteria and fungi.

In continuation of our work towards synthesizing bio-active molecules we developed and optimized the methodology for novel N -(3-chloro-2-oxo-4-phenylazetidin-1-yl)-4-(1 H -indol-3-yl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide analogues from readily available starting materials. We focused on the pressing demand to find eco-friendly pathways by means of catalytic optimization of the process. All synthesized compounds were screened for in vitro antibacterial and antifungal activities on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus pyogenes, Candida albicans, Aspergillus niger , and Aspergillus clavatus species.

The synthesis and antitumor activity of substituted benzo[ e ][1,2,4]triazino[2,3- c ][1,2,3]triazin-2-ones – novel electro-deficient tricyclic compounds – are described. These compounds were prepared by treatment of 3-(2-amino-3-R 2 -5-R 3 -phenyl)-6-R 1 -1,2,4-triazin-5(2 H )-ones with sodium nitrite in acetic acid. Spectral properties of synthesized compounds were studied and compared with spectral data of known 3-R-8-R 1 -10-R 2 -2 H -[1,2,4]triazino[2,3- c ]quinazolin-2-ones. These compounds are promising antitumor agents. The most active anticancer compound 3d was studied in dose-depended anticancer activity assay and its selective growth inhibition against breast cancer MDA-MB-468 cell line was established (GI 50 =0.41 μ m ).

N -Benzyl- N ′-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1 H -pyrazol-4-yl)urea (1) was obtained from antipyrine. The reaction of 1 with ethyl bromoacetate produced the 1,3-oxazole derivative 2 . Compounds 5a–c were obtained from antipyrine by three steps via intermediary of the ester 3 and hydrazide 4 . The microwave supported cyclocondensation of 5a–c with 4-chlorophenacyl bromide and ethyl bromoacetate afforded the corresponding 1,3-thiazoles 6 or 1,3-thia(oxa)zolidines 7 . The intramolecular cyclization of 5a–c in the presence of NaOH produced the corresponding triazoles 8a–c . The synthesis of the hybrid compound 9 containing a penicillin skeleton was carried out by the treatment of 8a with (+)-6-aminopenicillanic acid (6-apa) in the presence of formaldehyde. The structural assignments of new compounds were based on their elemental analysis and spectral (IR, 1 H-NMR, 13 C-NMR and LC-MS) data. All compounds except 1 and 7b show moderate antimicrobial activity.

A simple synthetic protocol was developed for the efficient synthesis of functionalized dispiro[indoline-3,1′-cyclobutane-2′,3″-indolines] with high diastereoselectivity. The reaction proceeds by cyclodimerization reaction of 3-phenacylideneoxindoles in the presence of a catalytic amount of photosensitizer Ru(bpy 3 )Cl 2 and visible light.

6-Alkylsulfanyl-1,4-dihydropyridines 5 bearing methoxyphenyl groups at various positions have been prepared by three different approaches. Multidrug resistance modulating (P-glycoprotein and multidrug resistance protein-1 inhibition) activity of 1,4-dihydropyridine derivatives 5 is comparable to that of verapamil.

The lactic acid-catalyzed reactions of ninhydrin and secondary enaminones were conducted by solvent-free grinding at room temperature to yield polycyclic 4b,9b-dihydroxy-4b,5,6,7,8,9b-hexahydroindeno[1,2- b ]indole-9,10-diones.

N -arylsulfonyl-1,2,3-triazoles were synthesized from 1,1-dibromo-2-arylethylenes via a one-pot reaction involving the Cs 2 CO 3 -mediated dehydrobromination process of the dibromoalkenes to produce alkynes followed by the Cu(I)-catalyzed Huisgen cycloaddition of the alkyne intermediates with tosyl azide.

Fused tricyclic heterocycles are useful compounds in many areas of chemistry. In this study, 2,3-diaminoquinolin-4(1 H )one ( 5 ), a key intermediate for the preparation of tricyclic compounds, was prepared from isatoic anhydride in four steps with high yields under mild conditions and an easy workup, with most of the reactions carried out in aqueous medium. Compound 5 was transformed into a series of tricyclic fused products 8 and 9 .