Synthesis, structure and properties of some 5-R-4-phenyl-1,2,4-triazole-3-thiol derivatives

Pyrrole, 1,2,4-triazole and indole derivatives belong to the group of aza-heterocyclic compounds, which have been associated with significant advances in the development of new drugs. Combining these heterocycles in one molecule increases the likelihood of detecting among these compounds substances with a certain kind of biological activity. The aim of the work was to optimize the conditions of synthesis and study the properties of S-alkylderivatives of 5-R-4-phenyl-1,2,4- triazole-3-thiol containing pyrrole and indolpropane fragments in their structure. Materials and methods. Pyrrole and indole-3-butanoic acid were used as key starting reagents. 4-Phenyl-5-(pyrrol-2-yl)-1,2,4-triazole-3- thiol was obtained by acylation, hydrazinolysis, nucleophilic addition of phenylisothiocyanate followed by intramolecular heterocyclization. For the synthesis of 5-(3-(indol-3-yl)propyl)-4-phenyl-1,2,4-triazole-3-thiol, the reaction of the interaction of the potassium salt of indole-3-butanoic acid with bromethane was carried out to obtain the appropriate ester. Subsequent stages of chemical conversion included hydrazinolysis reactions, the addition of phenylisothiocyanate, and alkaline cyclization. The structure of the obtained compounds was confirmed by data of elemental analysis, 1 H NMR spectroscopy and IR-spectrophotometry. The individuality of substances was established by using high performance liquid chromatography with diode-array and mass spectrometric detection. Results. S-alkylderivatives of 5-(3-(indol-3-yl)propyl)-4-phenyl-1,2,4-triazole-3-thiol and 4-phenyl-5-(pyrrol-2-yl)-1,2,4-triazole-3-thiol has been synthesized and their structure was established and studied physical properties. The synthesized compounds have been subjected to the in silico molecular docking study against the kinases of anaplastic lymphoma by using the 2XP2 ligand, lanosterol 14-α-demethylase by using the 3LD6 ligand, cyclooxygenase-2 by using the ligand which were downloaded from the protein data bank (PDB). Conclusions. Molecular docking has shown the ability of the synthesized compounds to influence the kinase activity of anaplastic lymphoma, cyclooxygenase-2 and lanosterol-14-α-demethylase.

Research in the field of indole compounds has been and remains relevant in the chemistry of heterocycles [1][2][3]. The reason for this interest is the participation of indole derivatives in the metabolic processes of living systems as biologically active compounds [6]. Derivatives of 1,2,4-triazole and pyrrole, which are structural fragments of a number of known drugs, are of no less interest [4,5]. A variety of chemical modification methods that can be used with respect to these heterocyclic systems, high biological potential with low toxicity give these objects of research all the signs of relevance and practical significance. During the last few years derivatives of indole have attracted much attention because of their special biological activity in medicine and agriculture.

Aim
The aim of our work was to search for promising compounds from the point of biological activity in a series of derivatives that combine heterocyclic fragments of pyrrole, 1,2,4-triazole, and indole.

Materials and methods
The study of physical-chemical properties of the obtained compounds was carried out using methods listed in the State Pharmacopoeia of Ukraine. Melting points were determined in open capillary tubes in a "Stanford Research Systems Melting Point Apparatus 100" (SRS, USA). The elemental analysis (C, H, N) were performed using the "Elementar vario EL cube" analyzer (Elementar Analysensysteme, Germany). IR spectra (4000 -400 cm -1 ) were taken off the module ALPHA-T of Bruker ALPHA FT-IR spectrometer (Bruker optics, Germany). 1 H NMR spectra (400 MHz) were recorded at "Varian-Mercury 400" spectrometer with SiMe 4 as internal standard in DMSO-d 6 solution. Chromatography-mass spectral studies were conducted on the instrument "Agilent 1260 Infinity HPLC" equipped with a mass spectrometer "Agilent 6120" (method of ionization -electrospray (ESI)).
Chemistry butanoate. To a mixture of 0.01 mol of 4-(indol-3-yl)butyric acid and 0.01 mol of sodium bicarbonate was added 15 ml of water. This mixture was boiled for 7 hours and evaporated.
Ethyl 4-(indol-3-yl)butanoate. A mixture of 0.01 mol of sodium 4-(indol-3-yl)butanoate was dissolved in 15.0 ml of DMSO at 80 °C and the equivalent of ethyl bromide was added. It was heated at 80 °C for 12 hours. Cooled down. The resulting solution was slowly poured into 60 ml of water. Orange oil was immediately formed and crystallized into orange crystals. This compound had a characteristic unpleasant odor. The crystalline precipitate formed was filtered off and dried.

4-(Indol-3-yl)butanhydrazide.
To a solution of 0.01 mol of ethyl 4-(indol-3-yl)butanoate in 20 ml of ethanol was added 0.022 mol of hydrazine monohydrate. It was heated to boiling for 6 hours. The resulting solution was slowly poured into 60 ml of water. Yellow crystals were formed immediately. The crystalline precipitate formed was filtered off and dried.

Molecular docking
Molecular docking was performed to obtain structural information on the interaction of the synthesized compounds and the corresponding biological structure. For this purpose, the Х-ray crystal structures of the corresponding biological targets from the protein database (PDB-ID) in complex with the standard ligand were previously downloaded: kinases of anaplastic lymphoma in the complex of crizotinib (2XP2), lanosterol 14-α-demethylase with ketoconazole (3LD6), cyclooxygenase-2 with indomethacin (4Z0L). The ligands (crizotinib, ketoconazole, indomethacin) were previously removed from the primary structures. It was carried out the joining of different ligands to the protein using AUT-ODOCK. The conformations of the ligand were analyzed in terms of energy, hydrogen bonding and hydrophobic interaction between the ligand and the receptor protein. A detailed analy sis of the ligand-receptor interactions was performed and the final coordinates of the ligand and receptor were saved as pdb files. The binding energy (FEB) of all compounds was calculated.
According to the IR spectroscopic data of the compounds 2.7, 2.8 which have triazole-3-thione structure, the observation of C=S stretching bands at 1380-1365 cm -1 and the absence of an absorption at about 2595-2550 cm -1 region cited for SH group have proved that these compounds were in the thionic form. In the IR-spectrum of synthesized alkyl derivatives observe deformation vibrations of alkyl groups in ranges from 630 to 1400 cm -1 and H-C-H fragment in a narrow area of frequency 1475-1370 cm -1 . For example, for CH 3 -group δ-vibrations occupied area at 1373-1380 cm -1 . Valence vibrations of bonds of C-H alkyl groups form bands in area 3100-2850 cm -1 . 840-780 cm -1 occupies a band of average intensity with a complex circuit that has several peaks (skeletal vibrations of C-C bonds). The synthesized compounds are also characterized by valence vibrations of the C=C bond of the aromatic rings at 1563-1515 cm -1 .
In the 1 H NMR spectra of compounds (2.2, 2.6, 2.8, 2.19-2.28) NH proton of the indole ring was seen as singlet at about 10.88-10.14 ppm. The integral intensity of the multiplet signals of the phenyl substituent protons, which are in the range 7.58-6.96 ppm, corresponds to their number in the proposed structures. The signal due to indol-CH 2 -methylene protons, present in all compounds, appeared at 3.03-2.09 ppm, as triplet or multiplet. Protons of the S-alkyl fragments (2.9-2.28) resonate in a strong field as a triplet or multiplet in area 3.21-0.84 ppm.
In the chromatic mass spectra, individual peaks of quasimolecular ions [M+1] are recorded, which have a high intensity, which confirms the structure and identity of the compounds 2.7, 2.8-2.28.   (2.19 (2.20   In order to investigate the probability of detection of molecules with anti-inflammatory activity, the interaction parameters with the active center of cyclooxygenase-2 (COX-2) were studied ( Table 2).
The molecular docking experiment was established that the synthesized compounds 3.6, 3.17-3.26 exhibit free energy of binding values from -7.7 to -8.8 kcal/mol. Molecular docking analysis also has shown that the complexes of the synthesized compounds interact with the 3LD6 protein with the best rates of change in Gibbs free energy in the Trp 213 region.