Volume 22, Issue 5

A facile synthetic route to an important intermediate 4-amino-2,6-dichloropyridine was developed. Oxidation of 2,6-dichloropyridine as a starting material gave pyridine N -oxide derivative which was subjected to nitration followed by reduction. Subsequent nitration of the product and nucleophilic displacement reaction were carried out to afford fully substituted energetic pyridine derivatives. Most of the synthetic reactions proceeded under mild conditions.

The reaction of arylmethylene derivatives of 3 H -furan-2-ones or 3 H -pyrrol-2-ones with N-benzylidenebenzylamine activated with the AcOAg/Et 3 N system to form spiropyrrolidynes was carried out for the first time.

New hybrid compounds containing flavanone and pyrazoline motifs were synthesized by microwave irradiation and conventional heating methods using one-pot synthetic strategy. The products were evaluated for their antimicrobial activity.

The crystal structure determination of oxazoline-1,2,4-triazine ligand 1f and pyridine-oxazoline ligand 2g was used to analyze their conformational preferences when forming complexes with metals. Proton nuclear magnetic resonance ( 1 H NMR), electrospray ionization mass spectrometry and UV-vis spectroscopy as well as theoretical calculation using molecular mechanics (MM) were adopted to study the composition and geometry of oxazoline-1,2,4-triazine ligands 1 complexes with copper(II) acetate monohydrate. The study revealed that during the complexation, (i) Cu(II) ion is reduced to Cu(I) upon the ligand-to-metal charge transfer transition and (ii) the ligands form with copper(I) 2:1 (L:Cu) complexes of tetrahedral geometry. On the basis of the findings, the catalytic cycle and the active transition state for the enantioselective nitroaldol reaction (the Henry reaction) catalyzed by 1 –Cu are proposed.

The synthesis and characterization of new copper-, magnesium- and cobalt- phthalocyanine complexes are reported. It appears that these complexes are not aggregated in THF in the concentration range of 1×10 −5 –1×10 −6 m . Additional structural and electronic data about the new complexes were obtained by calculations with the application of density functional theory at B3LYP/6-31G(d, p) level.

2-(2,4,6-Trioxo-[1,3,5]triazinan-1-yl)ethyammonium halides 3–5 were prepared starting from 2-(methylthio)-7,8-dihydroimidazo[1,2- a ]-1,3,5-triazin-4(6 H )-thione ( 1 ). First, compound 1 was S4-methylated to give 2,4-bis(methylthio)-6,7-dihydroimidazo[1,2- a ][1,3,5]-triazine ( 2 ) which, in turn, was hydrolyzed with corresponding aqueous solution of hydrogen halide. X-ray crystallographic study revealed that in crystals of 2-(2,4,6-trioxo-[1,3,5]triazinan-1-yl)ethylammonium iodide ( 5 ) a chain of alternatively arranged anions and cations extending along [001] is formed through polymeric (anion-π) n interactions.

5-( N -Ethylcarbazol-3-yl)thiophene-2-carbaldehyde (ECTC), was synthesized by Suzuki coupling reaction and characterized by 1 H NMR, 13 C NMR and elemental analysis. This compound strongly quenches fluorescence of Fe 3+ ion, whereas almost no quenching is observed in the presence of other metal ions including Na + , K + , Mg 2+ , Ca 2+ , Cu 2+ , Mn 2+ and Co 2+ . Under optimized conditions, the fluorescence intensity of ECTC is quenched in a linear fashion by Fe 3+ ion in a wide range of 0.1 μ m –10 μ m with the limit of detection below 0.1 μ m .

Starting with 4-piperidone, new 5,6,7,8-tetrahydroimidazo[2′,1′:2,3]thiazolo [5,4- c ]pyridines were synthesized. Structures of these compounds were confirmed by 1 H NMR, 13 C NMR, MS and elemental analysis.

The reaction of 2-allyl(propargyl)thioquinolin-3-carbaldehyde with halogens (Br or I) results in formation of 1-halogenomethyl(halogenomethylidene)-4-formyl-1,2-dihydrothiazolo[3,2- a ]-quinolinium trihalogenide. In the case of the propargylic derivative the process is stereoselective.

The three-component reaction of triphenylphosphine, dialkyl hex-2-en-4-ynedioate and arylidene-1,3-indanedione in dry DME at room temperature furnishes functionalized triphenylphosphanylidene-substituted 1′,3′-dihydrospiro[cyclopentane-1,2′-inden]-2-enes in 75–92% yields. 1 H NMR spectra and X-ray diffraction analysis indicate that the trans -isomer is predominately formed and the reaction has very high diastereoselectivity.

A four-component reaction including two equivalents of aldehyde, 1 H -indazol-6-amine and 1 H -pyrazol-5(4 H )-one proceeds smoothly to afford a series of spiro[pyrazole-4,8′-pyrazolo[3,4- f ]quinolin]-5(1 H )-ones in high yields under catalyst-free conditions.