2-position Of Pyridine Research Articles

Dearomative cyclization of pyridines/isoquinolines with cyclopropenones: access to indolizinones and benzo-fused indolizinones.

Dearomatization reactions provide a rapid approach to construct complicated molecules that are difficult to synthesize by traditional methods from simple aromatic compounds. Herein, we report an efficient dearomative [3+2] cycloaddition reaction of 2-alkynyl pyridines with diarylcyclopropenones, leading to the synthesis of densely functionalized indolizinones in moderate to good yields under metal-free conditions. In addition, this strategy can also be employed in dearomative cyclization of isoquinolines to access a variety of benzo-fused indolizinones. Density functional theory (DFT) calculations revealed that an appropriate substituent at the 2-position of pyridine is crucial to the dearomatization process.

Synthesis of a new functionalized pyridoxine derivatives based on 2-halopyridine-3,4-dicarbonitriles

Two new approaches to the synthesis of functionalized pyridoxine derivatives with hydroxymethyl groups at positions 3 and 4 of the pyridine ring have been implemented based on the transformations of 2-halopyridine-3,4-dicarbonitriles. The first path involves obtaining target compounds with a halogen atom in the 2-position of pyridine by reduction of intermediate pyridine-3,4-dicarboxylates with sodium borohydride. The second approach is based on the reduction of annelated furo[3,4-c]pyridin-3(1H)-ones and allows obtaining both 2-halogen- and 2-alkylamino-substituted pyridoxine derivatives.

Design and synthesis of conformationally constrained hydroxylated 4-phenyl-2-aryl chromenopyridines as novel and selective topoisomerase II-targeted antiproliferative agents

To develop novel selective topoisomerase II inhibitors, we designed and synthesized a series of conformationally constrained hydroxylated 4-phenyl-2-aryl chromenopyridines and evaluated their topoisomerase inhibitory activity and cytotoxicity against three human cancer cell lines (DU145, HCT15, and T47D) and a normal cell line (MCF10A). All of the prepared compounds displayed stronger or similar topoisomerase II inhibitory activity as well as cytotoxicity against three human cancer cell lines compared to etoposide. Compounds 10a, 10g, 11a, 11f, 11g, 12a, 12f, and 12g especially showed stronger topoisomerase II inhibitory activity as compared to etoposide at both 100μM and 20μM. A structure–activity relationship study revealed that hydroxyphenyl moiety at 4-position of pyridine and ortho-hydroxyphenyl or thienyl moiety at 2-position of pyridine has an important role in displaying selective topoisomerase II inhibition. The compound 12b with para-hydroxyphenyl and meta-hydroxyphenyl at 4- and 2-position of pyridine, respectively, showed the most significant cytotoxicity against all three cancer cell lines, whereas less cytotoxicity to a normal cell line as compared to adriamycin.

Hydrothermal Synthesis, Crystal Structure and Characterization of New Coordination Polymer [Co2(pydc)2(H2O)6] n ·2nH2O

A coordination polymer of cobalt(II) containing the pyridine-2,5-dicarboxylate (pydc) ligand and having the composition [Co2(pydc)2(H2O)6]n·2nH2O was prepared by the hydrothermal method. The coordination polymer was characterised by FTIR, single crystal XRD, SEM, TGA–DTA, and N2 Temperature Programmed Desorption, Brunauer, Emmett and Teller surface area. The polymer contains two cobalt(II) ions with slightly distorted octahedral geometry. The carboxylate group at the 2-position of pyridine acts as a bridging ligand between two cobalt metal ions and this expansion leads to formation of a 1-D chain-like coordination polymer. The coordination polymer chains are packed together by well-directed hydrogen bonds to generate a three dimensional mesoporous network. The N2 TPD study shows that the polymer is mesoporous in nature and possesses slit-shaped mesopores with average pore size diameter of 17.78 nm. SEM micrographs show well-defined channels in the solid crystals confirming the porosity of polymer. Thermogravimetric studies indicate the robust nature of the polymer. The polymer undergoes thermal decomposition in well-defined steps leading to the formation of cobaltous oxide as the end-product.

Microwave-Promoted Syntheses of Pyridine Carboxamides and tert-Carboximides from Novel 6-Acetylpyridine-2-carboxylic Acid

A novel 6-acetylpyridine-2-carboxylic acid (4) was obtained occasionally during the synthesis of asymmetric ethyl 6-acetylpyridine-2-carboxylate (3) from 2,6-dipiclinic acid (1). Compounds 3 and 4 could transform mutually under some specific conditions. Two reactions of distinctive types occurred when they reacted with the aromatic amines as precursors, due to different functional groups on the 2-position of pyridine in the molecules of 3 and 4: one was Schiff base condensation and the other was an amidation reaction. From the latter reaction, two series of new compounds, pyridine carboxamides (5a–d) and pyridine tert-carboximides (6a–h), resulted. The relevant reaction mechanism is discussed in detail.

Synthesis of 3,5-Dibromopyridines with –NH(CH2)mSO3Na (m = 3 and 4) Groups at the 2-Position of Pyridine and Use of the Dibromo Compound for Polymer Synthesis

Abstract Reactions of 2-amino-3,5-dibromopyridine with sultones gave 3,5-dibromopyridines with –NH(CH2)mSO3Na (m = 3 and 4) groups at the 2-position of pyridine. The obtained compound served as a starting material for polypyridine with –NH(CH2)mSO3H side chains.

Synthetic Studies on Fungicidal Agent. VII. Reaction of 2-Picoline and Aromatic Primary Amines (or Aromatic Nitro Compounds) in the Presence of Sulfur.

The condensation of 2-picoline with various aromatic primary amines (or nitro compounds) in the presence of sulfur was carried out at elevated temperature. This reaction was tentatively divided into three types : The first type is a simple thiopicolinoyl ; the second, a mixed type, yielding thiopicolinoyl and thiazolyl cyclization products ; and the last, unchanged (or resinous). It is noteworthy that protomeric amino group, such as that of N1-position of sulfanilamide and 2-position of pyridine, was active to some extent for this reaction. Oxidative cyclization of five thiopicolinoyl intermediates (XXI, XXIII, and XXIV) from dianisidine, sulfanilamide, homosulfanilamide, 2-aminopyridine, and 5-nitro-2-aminopyridine with potassium ferricyanide was unsuccessful, but not for (XXII) and (XXV). The chemical structure of these cyclization products was discussed on the basis of their ultraviolet spectral observation and electronic theory. Microbiological activity of these compounds will be reported elsewhere.