new diorganotin(iv) complexes of the type ph2snl2, bu2snl2 and me2snl2 of the ligands 2-thioacetic-5-phenyl-1,3,4-oxadiazole (hl1) and benzamidophenylalanine (hl2). have been synthesized and characterized by physico-chemical techniques such as (elemental analysis, and electrolytic conductance) and spectral uv-visible, ir and 1h, 13c and 119sn nmr). monomer structures for the complexes, bidentat...

The reaction of aryl isoselenocyanates 8 with methyl 3-amino-4-chloro-1-ethylpyrrolo[3,2c]quinoline-2-carboxylate (6) in boiling pyridine leads to tetracyclic selenaheterocycles of type 9 in high yield (Scheme 3). A reaction mechanism via an intermediate selenoureido derivative A and cyclization via nucleophilic substitution of Cl by Se is proposed (Schemes 3 and 5). The reaction of 6 with 4-br...

Several new pyrazole, pyridine, [1,2,4]triazolo[1,5-α]pyrimidine, benzimidazo[1,2-a]pyrimidine and 1,2,4-triazolo[3,4-c][1,2,4]triazine derivatives incorporating a thiophene moiety were synthesized from (E)-ethyl 5-(3-(dimethylamino)acryloyl)-4-phenyl-2-(phenylamino)thiophene-3-carboxylate (1). The structures of the newly synthesized compounds were confirmed by IR, ¹H-, (13)C-NMR, mass spectral...

Detailed mechanistic studies on the palladium-catalyzed direct arylation of pyridine N-oxides are presented. The order of each reaction component is determined to provide a general mechanistic picture. The C-H bond cleaving step is examined in further detail through computational studies, and the calculated results are in support of an inner-sphere concerted metalation-deprotonation (CMD) pathw...

The title compound, [Zn(H(2)O)(6)][Zn(C(7)H(4)NO(4))(3)](2), consists of two [Zn(py-2,3-dcH)(3)](-) anions (py-2,3-dcH is 3-carboxy-pyridine-2-carboxylate) and one [Zn(H(2)O)(6)](2+) cation. The anion is a six-coordinate complex located on a threefold rotation axis with a slightly distorted octa-hedral geometry around Zn(2+) ion. The cation is also six-coordinate with an octa-hedral geometry ar...

Arsenic trioxide (As2O3) has been used with success in the treatment of acute promyelocytic leukemia. However, resistance to arsenite agents reduces their efficacy. We have isolated arsenite-resistant human epidermoid carcinoma KB cells, termed KAS. KAS cells were resistant to sodium arsenite (22-fold) and showed a reduced accumulation of arsenite as a result of an active efflux mechanism. Furt...

A new series of pyrazolylpyridines was prepared by reaction of ethyl-3-acetyl-1,5-diphenyl1H-pyrazole-4-carboxylate with the appropriate aldehyde, malononitrile, or ethyl acetoacetate and an excess of ammonium acetate under reflux in acetic acid. Similarly, two novel bipyridine derivatives were prepared by the above reaction using terephthaldehyde in lieu of benzaldehyde derivatives. In additio...

The paper reports the syntheses, crystal structures, thermal and (photo)magnetic properties of spin crossover salts of formula [Fe(bpp)2](C6H8O4)·4H2O (1·4H2O), [Fe(bpp)2](C8H4O4)·2CH3OH·H2O (2·2MeOH·H2O) and [Fe(bpp)2](C8H4O4)·5H2O (2·5H2O) (bpp = 2,6-bis(pyrazol-3yl)pyridine; C6H8O4 = adipate dianion; C8H4O4 = terephthalate dianion). The salts exhibit an intricate network of hydrogen bonds be...

Two novel polyoxotungstate-based rare earth compounds, [(C5H5N-CO2)2Ln(H2O)3]2[H2W12O40] · nH2O (C5H5N-CO2 = pyridine-4-carboxylate; Ln = La3+ (1), n = 5; Ce3+ (2), n = 7), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and TG analyses. The isostructural compounds 1 and 2 exhibit onedimensional (1D) zig-zag chains,...