Green Synthesis of Novel 5-Arylazo-2- [(2S, 3S, 4R, 5R)-3, 4, 5- trihydroxy-6-(hydroxymethyl) tetrahydro-2H-pyran-2-yloxy]-4, 6-dimethyl 3-nicotinonitrile

Copyright: © 2017 Areef MMH, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Green Synthesis of Novel 5-Arylazo-2[(2S, 3S, 4R, 5R)-3, 4, 5trihydroxy-6-(hydroxymethyl) tetrahydro-2H-pyran-2-yloxy]-4, 6-dimethyl 3-nicotinonitrile


Introduction
Pyridine nucleus is one of the most interesting nucleus in organic synthesis. Many uses of pyridines derivatives were investigated in the recent decades especially fluorinated derivatives. One of the recent researches discovered that high tuberculostearic activity of pyridine was observed [1,2].
Also from the amazing character of some pyridine is its high fluorescence activities which was used as molecular sensor of picric acid [3].
It has been of great importance in the exploring of some novel antimicrobial compounds in veterinary as well as human medicine worldwide. Genetic mutation and acquisition of mobile drug resistance genes of microorganisms is a very great resistance and barrier in treating animal and human patients with infectious diseases [4,5]. The importance of the synthesis of novel derivatives of pyridine nucleosides due to their potential use to treat various diseases, such as hepatitis cancer and microbial infections [6][7][8][9][10].
Fluorinated derivatives of pyridines are of high significance in pharmaceutical and medicinal chemistry [11]. Synthesis of poly substituted fluroarylazopyridone by using green protocol is of great effect in synthetic chemistry and also in pharmaceutical chemistry [12]. The presence of fluorine atoms in the molecule can change its lipophilicity, which also affect and change the rate of transportation through lipid membranes [13]. Achievement of green and sustainable chemistry protocol instead of classical methods synthetic chemistry nowadays is of high interest, especially in synthesis of some novel Fluro arylazo pyridine derivatives (1a-e) and their nucleosides (3a-e).

Graphical Abstract
Conventional method: To a solution of 2(1H)-pyridone (1a-e) (10 mmol) in DMF (10 ml) where be added potassium hydride (4.76 mmol) where be added under nitrogen and the suspension will be stirred at 60°C. After 2 h, the 2, 3, 4, 6-tetra-O-acetyl-α-D-glucopyranosyl bromide (5) (11 mmol, 4.52 g), was added and the solution will be stirred at room temperature for 18 h. The solvent had been evaporated and the residue had been partitioned between CHCl 3 (30 mL) and water (30 mL). The combined organic extracts where be dried on (Na 2 SO 4 ), filtered and evaporated to dryness. The products had been dried and purified using column chromatography to gain the compounds (2a-e) (Schemes 1 and 2).

General procedure for nucleoside deacetylation
Triethyl amine method: Triethylamine (1.0 mL) had been added to a solution of glucosides (2a-e). (0.001 mol) in (10 mL MeOH and 3 drops of water). The mixture had been stirred for 18 hours at room temperature. The solvent had been evaporated under reduced pressure and the residue was evaporated with MeOH until triethylamine had removed. The residue was crystallized from appropriate solvent to get compounds (3a-e).
Methanol and dry ammonia: A solution of protected glucosides (0.5 g) in 20 mL of dry methanol at 0°C (2a-e) was subjected to passing of dry ammonia for 30 minutes. The reaction mixture was stirred until it had done and was investigated by TLC (10-12 h). The resultant mixture was concentrated under reduced pressure to afford a crude solid. The products were purified using silica gel chromatography (chloroform: methanol, 20:1), then the products were crystallized from methanol to get the final products (3a-e).

Biology
Novel fluroazopyridone compounds were tested for their antimicrobial activity and it was determined using a modified Kirby-Bauer disc diffusion method [14]. Briefly, 100 µl of the test bacteria/ fungi were grown in 10 ml of fresh media until they reached a count of approximately 10 8 cells/ml for bacteria or 10 5 cells/ml for fungi [15]. 100 µl of microbial suspension was spread onto agar plates corresponding to the broth in which they were maintained. Isolated colonies of each organism that might be playing a pathogenic role should be selected from primary agar plates and tested for susceptibility by disc diffusion method. The many media available, NCCLS recommends Mueller-Hinton agar due to [16,17]. It results in good batch-to-batch reproducibility. Disc diffusion method for filamentous fungi tested by using approved standard method (M38-A) developed [18] for evaluating the susceptibilities of filamentous fungi to antifungal agents. Disc diffusion method for yeasts developed by using approved standard method (M44-P) [19]. Plates inoculated with filamentous fungi as Aspergillus flavus at 25°C for 48 hours; Gram (+) bacteria as Staphylococcus aureus, Bacillus subtilis; Gram (-) bacteria as Escherichia coli, Pseudomonas aeuroginosa they were incubated at 35-37°C for 24-48 hours and yeast as Candida albicans incubated at 30°C for 24-48 hours and, then the diameters of the inhibition zones were measured in millimetres [20]. Standard discs of Ampicillin (Antibacterial agent), Amphotericin B (Antifungal agent) served as positive controls for antimicrobial activity but filter discs impregnated with 10 µl of solvent (distilled water, chloroform, DMSO) were used as a negative control. The agar used is Meuller-Hinton agar that is rigorously tested for composition and pH. Further the depth of the agar in the plate is a factor to be considered in the disc diffusion method. This method is well documented and standard zones of inhibition have been determined for susceptible and resistant values. Blank paper disks (Schleicher & Schuell, Spain) with a diameter of 8.0 mm were impregnated 10 µl of tested concentration of the stock solutions. When a filter paper disc impregnated with a tested chemical is placed on agar the chemical will diffuse from the disc into the agar. This diffusion will place the chemical in the agar only around the disc. The solubility of the chemical and its molecular size will determine the size of the area of chemical infiltration around the disc. If an organism is placed on the agar it will not grow in the area around the disc if it is susceptible to the chemical. This area of no growth around the disc is known as a "Zone of inhibition" or" Clear zone". For the disc diffusion, the zone diameters were measured with slipping calipers of the National Committee for Clinical Laboratory Standards. Agar-based methods such as E-test and disk diffusion can be good alternatives because they are simpler and faster than broth-based methods [21][22][23].

Biology
It has been of great importance in the exploring of some novel antimicrobial compounds in veterinary as well as human medicine   of alkali and although anhydrous media is useful to reduce the amount of alkali, but catalytic reaction may be applied. But in fact, a mixture of Triethylamine in MeOH and water be used in deacetylation or a mixture of methanol and dry ammonia where he also used (Table 4).
worldwide. Genetic mutation and acquisition of mobile drug resistance genes of microorganisms is a very great resistance and barrier in treating animal and human patients with infectious diseases. All investigated compounds show different antibacterial and antifungal activities, these results where be due to the newly derivatives formed from fluroazo pyridone and their glucosides. The most active compounds were 1a, 3a, 1c, 3c although most of them showed good activity.