The Biginelli-type reactions of 5-amino-3-arylpyrazole-4-carbonitriles with aldehydes and 1,3-dicarbonyl compounds were studied in details. New pyrazolopyrimidines and pyrazoloquinazolines were synthesized through the reaction of 5-amino-3-arylpyrazole-4-carbonitriles with aromatic aldehydes and active 1,3-dicarbonyls (acetyl acetone, acetoacetanilides or dimedone) in the boiling DMF. The reaction requires no catalysts.

The Tsuji-Trost reaction is palladium-catalyzed substitution using nucleophile with a substrate containing a leaving group in an allylic position. This reaction can be used for the formation of the carbon-carbon, carbon-nitrogen, and carbon-oxygen new bonds by applying appropriate nucleophiles such as active methylenes, enolates, amines, and phenols. The leaving group can be for example acetate, carbonate or a halide.

Herein, we present the synthesis of PHOX ligands from amino alcohols derived from α-pinene and β-pinene. The resulting oxazolines were used as chiral ligands in palladium catalyzed asymmetric allylic substitution reaction. We studied the influence of the leaving group in a substrate and the type of nucleophile for enantioselectivity of the reaction.

One of the main aims of modern organic synthesis is the preparation of the compounds in optically pure form. Reactions catalyzed by transition metals with chiral ligands are widely used in the stereocontrolled syntheses. Chiral diphosphine ligands belong to one of the most important class of ligands employed for the transition metal catalysis. It is important to search for the new structures of this class, as well as new methods for their synthesis.

Herein, we present the synthesis of the new rigid bicyclic chiral diphosphines derived from β-pinene and α-pinene. Diphosphines were prepared in optically pure form and they were applied as ligands in transition metal catalyzed enantioselective reactions.

Acknowledgments 

We wish to thank the financial support received from National Science Centre Preludium 4 No. 2012/07/N/ST5/02194.

Multicomponent reaction of cyclic 1,3-diketones, isatin and malononitrile in water in the presence of graphene oxide decorated Fe₃O₄@ SiO₂ (Fe₃O₄@SiO₂-Go) catalyst leads to the wide range of spirooxindole derivatives in high to excellent yields. Easy preparation, recovery, and eco-friendliness of the catalyst, avoiding the use of any hazardous solvent, shorter reaction time and straightforward work-up procedure consist the remarkable advantages of this protocol.

Pure chiral amines play a key role in many branches of human life, because they are widely applied as starting materials for the total syntheses of natural products or drugs. Moreover, a large number of them exhibit a wide range of bioactivities by acting on the central nervous system, decreasing a blood pressure, and smooth muscle relaxation. On the other hand, optically active amines and their derivatives have been utilized successfully in a widespread modern asymmetric syntheses as chiral catalysts and building blocks.

Several strategies for the synthesis of chiral amines have been reported in the literature. However, there is still a wide requirement to develop better approaches. Herein, we present an alternative method based on the enantioselective reduction of cyclic and acyclic imines with borane using chiral terpenyl spiroborate esters as catalysts. Our earlier studies showed that spiroborate esters can be successfully utilized as catalysts in the enantioselective reduction of ketones, and their derivatives, with borane giving the corresponding alcohols with very good yields and enantiomeric excesses. On the other hand, this class of catalysts are much more stable towards moisture and air than other boron catalysts because of the unique structure containing a characteristic O₃BN framework, where B-N bond is a coordinate bond. These facts make spiroborate esters an interesting and hopeful variant for obtaining chiral compounds.

The azo-azomethine dyes 2-[(4-amino-1,2,5-oxadiazol-3-ylimino)methyl)-4-(phenyl diazenyl]phenol (2a-h) have been synthesized from the condensation reaction of  3,4-diamino -1,2,5-oxadiazole with 2-hydroxy-5-[(E)-(aryldiazenyl)]benzaldehyde(1a-h) in methanol. The structures of dyes have been characterized by elemental analysis, mass, IR, UV-Vis, ¹H and ¹³С NMR spectroscopy. UV–Vis absorption spectra indicated enol–keto tautomeric and positive solvatochromism in compounds 2a-h which is dependent on the substitution, solvent, pH and environment temperature. The synthesized compounds were investigated for their in vitro antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Compounds substituted with electron donating groups, such as, alkyl and methoxy groups showed moderate to mild antioxidant activity. The in-vitro antibacterial activity of all compounds was determined by disc diffusion method. The tested compounds showed varying degree of inhibition against B. cereus and S. aureus strains. However, E.coli and K. pneumonia were not sensitive to any of the tested samples.

Absorption storage systems in combination with solar thermal systems are a potential attempt for the reduction of greenhouse gases.¹ The currently used sorption media like LiCl or LiBr show problems concerning crystallization, corrosion or low storage capacity.^{2, 3} Imidazolium and Choline based ILs in combination with organic anions may be an alternative to the classical hygroscopic salt solutions, because they are able to quickly absorb large amounts of water in an exothermic process. To optimize the sorption system we have screened the latter device parameters, especially the solution behavior of the ILs to determine structure-property relationships and improve the performance. Therefore, a calorimetric analysis offers an insight in the interaction between cation, anion and water.⁴ In combination with other investigation, we hope to obtain a simulation of the sorption process.

1. C. Janiak and S. K. Henninger, Nachr. Chem., 2013, 61, 520-523.
2. P. Wasserscheid and M. Seiler, ChemSusChem, 2011, 4, 459-463.
3. M. Uerdingen, C. Treber, M. Balser, G. Schmitt and C. Werner, Green Chem, 2005, 7, 321-325.
4. T. Brünig, K. Krekić, C. Bruhn and R. Pietschnig, Chem. Eur. J., 2016, DOI: 10.1002/chem.201602723, n/a-n/a.

The reaction of S-alkyl thiobarbiturates with aromatic aldehydes and malononitrile (or arylmethylidenemalononitrile) leads to hitherto unknown 4Н-pyrano[2,3-d]pyrimidines. Plant growth regulating activity and herbicide antidote activity were studied in the series of the obtained compounds. We found that ethyl {[7-amino-6-cyano-5-(4-methoxyphenyl)-4-oxo-3,5-dihydro-4Н-pyrano[2,3-d]pyrimidin-2-yl)thio}acetic acid revealed moderate activity as 2,4-D antidote.

In recent years the development of new and more sophisticated biomaterials have led to the production of different types of implants and prostheses that effectively replace injured or malfunctioning body parts. As a result, there has been an increasing use of these dental, cardiovascular and synthetic substitutes.

The Ti6Al4V alloy has been widely investigated as an implant biomaterial because of its strength, high density and resistance to corrosion processes, as well as a good osseointegration capability.

However, due to its high surface roughness, the alloy is prone to adhesion of both Gram-negative and Gram-positive bacteria, such as P. aeruginosa and S. aureus, respectively. Bacterial adhesion on the surface of titanium-based medical devices begins with the formation of weak Van der Waals bonds. (Rautray et al., 2010) If these pathogens are not promptly removed, they begin to excrete a glue-like substance that anchors them more firmly, and accumulation of new bacteria in this scaffold, called biofilm, occurs. Biofilms are formed by a complex polymeric matrix that protects the pathogens from antibiotics. Hence, once the infection has taken place and the biofilm is formed, it is very difficult to eradicate. These events may ultimately lead to implant failure and the need for its removal, with a high social and economic cost associated. (Ando et al., 2010)

In order to mitigate the proliferation of bacterial biofilms functionalisation and anchoring of bactericidal compounds on the biomaterial have been reported. (Ang et al., 2016)

Some 2-aminoimidazoles, isolated from marine sponges of the genus Leucetta, show antibiotic activity against various pathogenic bacteria (Mai, T. et al. 2015; Žula et al., 2015). In previous studies, it has been observed that 2-aminoimidazole derivatives bearing halide atoms in positions 4 and 5 inhibit by 90% the formation of bacterial biofilms of S. aureus (Fung et al., 2014).

With all this in mind, we have reasoned that a chloro-substituted aminoimidazol would represent an interesting molecule to be anchored on the biomaterial surface, and that it might give the alloy some antibacterial protection.

Hence, the objectives of this piece of work are:

• To synthesise 2-amino-4- (4-chlorophenyl) imidazole using conventional as well as microwave assisted procedures.
• To modify the Ti6Al4V surface and by passivation and silanisation processes, to enable it to generate a high density of functional groups of amino or carbonyl type to facilitate interaction with the 2-aminoimidazole.
• To anchor the 2-amino-4- (4-chlorophenyl) imidazole to the silanised surface by means of non-covalent interactions.
• To characterise the modified material be X-ray photoelectron spectroscopy.

Our results will be presented in this communication.

REFERENCES

Ando, N., Terashima, S. (2010). A novel synthesis of the 2-amino-1H-imidazol-4- carbaldehyde derivatives and its application to the efficient synthesis of 2-aminoimidazole alkaloids, oroidin,hymenidin, dispacamide, monobromodispacamide, and ageladine Aq. Tetrahedron, 66, 6224-6237.

Ang, G., Ruiqiang , H., Chu, P. (2016). Recent advances in anti-infection surfaces fabricated on biomedical implants by plasma-based technology. Surf. Coat. Tech., 1-5.

Fung, S.-Y., Sofiyev, V., Schneiderman, J., Hirschfeld, A., Victor, R., Woods, K., de Voogd, N. (2014) Unbiased screening of marine sponge extracts for anti-inflammatory agent combined with chemical genomics identifies girolline as an inhibitor of protein synthesis. ACS Chem. Biol, 9(1), 247–257.

Mai, T., Tintillier, F., Lucasson, A., Moriou, C., Bonno, E., Petek, S., Magré, K., Al-Mourabit, A., Saulnier, D., Debitus, C. (2015) Quorum sensing inhibitors from Leucetta chagosensis Dendy, 1863. Lett. Appl. Microbiol.,61(4), 311-317.

Rautray, T., Narayanan, R., Kwon, T.-Y., Kim, K.-H. (2010) Review Surface Modification of Titanium and Titanium Alloys by Ion Implantation. J. Biomed. Mater. Res. B Appl. Biomater., 93(2), 581-591.

Žula, A., Kikelj, D., Ilaš, J. (2015) Chemistry of 2-Aminoimidazoles. J. Heterocyclic Chem., 1-11.

Molecular docking study was performed using Maestro Schrödinger suite 8.5 mainly on twenty nine phytoconstituents reported from the plant Aerva lanta for their antimicrobial potential. The crystal structure of protein data bank (PDB-ID: 3SRW) was obtained from RCSB (Research Collaboratory for Structural Bioinformatics) website. The ligands were obtained from the reported literature search of Aerva lanta plant. The top hits were analyzed for their binding affinity with the dihydrofolate reductase enzyme. The docking results revealed that rutin (Glide score: -11.75) exhibited better binding interaction to dihydrofolate reductase receptor.