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• 490-11-9 3,4-pyridinecarboxylic acid 

Relevant academic research and scientific papers

First Report on Crystal Engineering of Hg(II) Halides with Fully Substituted 3,4-Pyridinedicarboxamides: Generation of Two-Dimensional Coordination Polymers and Linear Zig-Zag Chains of Mercury Metal Ions

Two new ligands N,N,N′,N′-tetraisopropyl/tetraisobutyl-3,4-pyridinedicarboxamide L1-L2 and six of their Hg(II)X2 complexes (where X = Cl-, Br-, and I-) have been synthesized and characterized. Single crystal X-ray structures of three complexes of L1 (1-3) with HgCl2/Br2/I2 and two complexes of L2 (4-5) with HgCl2/Br2 show that these are two-dimensional (2D) coordination polymers, with three different (one new) topologies and five coordinated Hg(II) ions, in square pyramidal coordination. Complex 6, of L2 with HgI2, is a dimer with a four coordinated tetrahedral Hg(II) ion. The ligands behave as two- or three-connecting linkers for forming coordination polymers (CPs) but only one-connector in the dimer. Various types of hydrogen bonding and other noncovalent interactions have been calculated, analyzed, and discussed for all the complexes and the ligand L1. Although the large size and soft character of iodide coupled with the steric effects of large isobutyl groups are mainly responsible for a change in the primary structure of 6, a significant role of the semilocalized LP···π and C-H···O noncovalent interactions into this has also been found. The latter transform this dimer into a stable 2D hydrogen-bonded network instead of a coordination polymer. The unique halide bridged 2D structure of 1 forms one-dimensional zig-zag chains of metal ions owing to the mercurophilic interactions. Weaker interactions of the same kind further extend along the basic skeleton of 2D CP and are facilitated by LP···π, strong C-H···Cl and C-H···N(py) interactions.

Acetic anhydride mediated condensation of aromatic o-diacid dichlorides with benzimidazoles to provide electro-reducible p-dione adducts

Acetic anhydride mediates a facile and rapid condensation of benzimidazole with aromatic o-diacid dichlorides to precipitate p-dione adducts in excellent yields. Condensation with pyridine-3,4-dicarbonyl dichloride produced a 1:1 mixture of isomeric p-diones. The X-ray crystal structure of one of the latter isomers revealed unusual high density, and inter-layer separation similar to graphite. Cyclic voltammetry demonstrated that p-dione is capable of two consecutive one-electron-reductions with formal potentials influenced by the fused (hetero)aromatic and substituent effects.

Synthesis and Biological Evaluation of Oral Prodrugs Based on the Structure of Gemcitabine

A series of oral prodrugs based on the structure of gemcitabine (2′,2′-difluorodeoxycytidine) were synthesised by introducing an amide group at the N4-position of the cytidine ring. A total of 16 compounds were obtained, and their chemical and biological characteristics were evaluated. The half-maximal inhibitory concentrations (IC50s) for most of these compounds were higher than that of gemcitabine in vitro. Compounds 5d and 5m, the representative compounds, were examined in terms of their physiological stabilities and pharmacokinetics. Compound 5d showed good stability in PBS and simulated intestinal fluid, and an analysis of its pharmacokinetics in mice suggested that the introduction of an amide group to gemcitabine could greatly improve its bioavailability. Further evaluation of compound 5din vivo showed that this compound possesses higher activity than gemcitabine against the growth of HepG2 human hepatocellular carcinoma cells and HCT-116 colon adenocarcinoma cells with less toxicity to animals. These results suggest that compound 5d could be further developed as a potential oral anticancer agent for clinical applications in which gemcitabine is currently used. A series of oral prodrugs based on the structure of gemcitabine were synthesized. Physiological and metabolic stabilities, pharmacokinetics and antitumor activities were evaluated for representative compounds.

Grignard Reactions on Ortho Dicarboxylic Arene Derivatives. Synthesis of 1,3-Dithienylisothianaphthene Compounds

1,3-Dithienylisothianaphthene (10a) is obtained through ring closure of 1,2-dithienoylbenzene (7a). The synthesis of 7a has been accomplished based on a Grignard reaction by adding 2-thiophene-magnesium bromide to 1,2-di(S-(2-pyridinyl)) benzenedithioate (6b) to obtain 7a in a yield of 95%. The use of 6b avoids the formation of the corresponding 3,3-dithienyl-3H-isobenzofuran-1(3H)-one (dithienylphthalide, 8). The same procedure is applied to obtain 1,3-dithienyl-4,5,6,7-tetradeuterioisothianaphthene (10b) and 1,3-dithienyl-4,5,6,7-tetrafluoroisothianaphthene (10c). The synthesis of the 2,3-dithienoylpyridine (12a), 3,4-dithienoylpyridine (12b), and 2,3-dithienoylpyrazine (12c) however fails. The presence of nitrogen in the central ring system influences the result of the Grignard reaction. Possibly the free electron pair of the nitrogen interferes with the formation of a stable six-membered ring intermediate which is essential for the diketone formation.