Synthesis of Some New Polyfunctionalized Pyridines

Dicyanopyridine derivatives: One-pot preparation, ACQ-to-AIE transformation, light-conversion quality and photostability

Low cost and strong fluorescence emission are two important guarantees for luminogens used as light conversion agents. By one-pot multicomponent approach and inexpensive starting materials, three dicyanopyridine (DP) derivatives named as DCP (2-amino-6-methoxy-4-phenylpyridine-3,5-dicarbonitrile), DCO (2-amino-6-methoxy-4-(4-methoxyphenyl) pyridine-3,5-dicarbonitrile) and DCC (2-amino-4-(4-cyanophenyl)-6-methoxypyridine-3,5-dicarbonitrile) were designed and synthesized. Meanwhile, the ACQ-to-AIE transformation was successfully realized by altering substituent groups rather than traditional rotor-stator theory. Based on crystal analysis and theoretical calculations, the ACQ-to-AIE transformation is attributed to the tunable stacking modes and intermolecular weak interactions. Owing to matched fluorescence emission, low lost, high yield, and AIE activity, DCC is used as light conversion agents and doped in EVA matrix. The light conversion quality confirms that DCC can not only convert ultraviolet light, but also significantly improve the transmittance of 25 %/40 % EVA, whose photosynthetic photon flux density at 400-500 nm and 600-700 nm increased to 30.67 %/30.21 % and 25.37 %/37.82 % of the blank film, respectively. After 20 h of UV irradiation (365 nm, 40 W), the fluorescence intensities of DCC films can maintain 92 % of the initial values, indicating good photostability in the doping films. This work not only provides an excellent and low-cost light conversion agent, but also has important significance for ACQ-to-AIE transformation of luminogens.

An efficient methodological approach for synthesis of selenopyridines: generation, reactions, anticancer activity, EGFR inhibitory activity and molecular docking studies

In the present work, we successfully synthesized Se-alkyl selenopyridines 1 and 3, selenopheno[2,3-b]pyridine 2, and bis-selenopyridine 4 derivatives using an eco-friendly method by utilizing NaHSe instead of toxic hydrogen selenide. The effect of the temperature on the reaction was screening at various temperatures. The regiospecific reaction of selenopyridine 1 with bromine afforded an unexpected product 4,6-diamino-5-bromo-2-[(cyanomethyl)selenyl]-pyridine-3-carbonitrile (5), which was cyclized to selenopheno[2,3-b]pyridine (7) by refluxing in the presence of TEA. While its treatment with thiophenol and/or p-chlorothiophenol gave 8a, b. On the other hand, its reaction with aminothiophenol afforded 2-(benzo[d]-thiazol-2-yl)-5-bromoselenopheno[2,3-b]pyridine-3,4,6-triamine (9). Also, N-(2-cyano-4-methyl-5H-1-seleno-3,5,8-triazaacenaphthylen-7-yl)acetamide (11) and a novel series of selenoazo dyes 12a-d were synthesized by treatment of selenopheno[2,3-b]pyridine 2 with acetic anhydride and/or diazonium chlorides of aromatic amines, respectively. Then, we ascertained the potential activity of synthesized compounds against highly metastatic prostate cancer cells (PC-3) and osteosarcoma cells (MG-63) and found that 12a, 12b, 12c, and 12d were more cytotoxic than doxorubicin in both tested cell lines, showing nearly the same anticancer activity with IC50 values ranging from 2.59 ± 0.02 µM to 3.93 ± 0.23 µM. Mechanistically, the most potent compounds 12a and 12b proved to be potent EGFR inhibitors with IC50 values of 0.301 and 0.123 µM, respectively, compared to lapatinib as a positive reference (IC50 = 0.049 µM). Moreover, the docking results are in good agreement with the anticancer activity as well as the EGFR inhibitory activity, suggesting these two compounds as promising EGFR anticancer candidates.

Synthesis and Insecticidal Evaluation of 3,5-Dicyanopyridines Against Cotton Aphids via Microwave-Assisted Multicomponent Reactions

Certain 2-amino-6-alkoxy-4-arylpyridine-3,5-dicyanide 1a-e were prepared via a straightforward process using microwave technology rather than conventional methods. This involved reaction of arylidenemalononitrile thru propanedinitrile in the occurrence of sodium alkoxide under MW. While, their positional isomer 4-amino-6-alkoxy-2-arylpyridine-3,5-dicyanide 3a-j have been separated from the reaction of aryl aldehydes with 2-aminoprop-1-ene-1,1,3-tricarbonitrile 2 in the presence of sodium alkoxide using microwave technic. Furthermore, the insecticidal properties of all synthesized compounds were observed with respect to Cotton aphid nymphs and adults. Neonicotinoid pesticides are indicated as the most effective pesticides toward aphids and many other pests. Many insecticides are discovered as novelties. As a result, several pyridine compounds were chemical method synthesized to serve as equivalents of neonicotinoids, a broad class of insecticides. With LC50 value of 0.03 mg/L, components 3g exhibit the highest insecticidal bioactivity. This work discusses how to find new chemicals that could be used as insecticidal agents in the future.

Functionalized Pyridines: Synthesis and Toxicity Evaluation of Potential Insecticidal Agents against Aphis craccivora

Using ultrasound technology instead of traditional methods, some pyridine derivatives were prepared by a simple procedure via a four-component reaction of different aromatic aldehydes, acetyl aryl, sodium alkoxide, and malononitrile, and additionally, all prepared compounds were monitored for insecticidal activities toward nymphs and adults of cowpea aphid. Though a lot of insecticides are discovered as a novelty on the other hand, neonicotinoid compounds are reflected as the most affected insecticides against aphids and many other pests. Thus, some of the pyridine derivatives were chemically prepared as analogues to a large group of insecticides called neonicotinoids. Under laboratory conditions, the toxicity of these components was measured toward adults and nymphs of Aphis craccivora. With respect to the LC50 values, components 1f, 1d, and 1c have the utmost insecticidal bioactivity, with values of 0.080, 0.098, and 0.127 mg/L. This work covers the way to discover novel compounds for the prospective use as insecticidal representatives.

Synthesis, characterization and anticancer activities of Zn2+, Cu2+, Co2+ and Ni2+ complexes involving chiral amino alcohols

A new type of coordination complexes related with the first transition metal and chiral amino alcohols can effectively fight against the human tumour cell line A549 with an IC50 value of 17.71 μM.

Catalyst-Solvent System for PASE Approach to Hydroxyquinolinone-Substituted Chromeno[2,3-b]pyridines Its Quantum Chemical Study and Investigation of Reaction Mechanism

The Pot, Atom, and Step Economy (PASE) approach is based on the Pot economy principle and unites it with the Atom and Step Economy strategies; it ensures high efficiency, simplicity and low waste formation. The PASE approach is widely used in multicomponent chemistry. This approach was adopted for the synthesis of previously unknown hydroxyquinolinone substituted chromeno[2,3-b]pyridines via reaction of salicylaldehydes, malononitrile dimer and hydroxyquinolinone. It was shown that an ethanol-pyridine combination is more beneficial than other inorganic or organic catalysts. Quantum chemical studies showed that chromeno[2,3-b]pyridines has potential for corrosion inhibition. Real time ¹H NMR monitoring was used for the investigation of reaction mechanism and 2-((2H-chromen-3-yl)methylene)malononitrile was defined as a key intermediate in the reaction.