untitled ISSN 215 Synthes 2‐merca Monther F Department of P * Corresponding Tel.: +964.770.5 ARTICLE IN DOI: 10.5155/e Received: 13 Oc Received in rev Accepted: 14 No Published onlin Printed: 31 Mar KEYWORDS 2‐MBT Chalcones Microwave Malononitrile Ultrasonic meth 2‐Aminonicotin 1. Introduct Microwa tacular acce consequence mass, which methods. Hig pathways are [1]. Moreove tional heatin In most cas free techniq alternative to 2‐Mercap possess vario [3,4], anti‐m activity [11 gastroesopha [12]. The N‐a very useful in compounds such as: anti antioxidant [17]. 53‐2249 (Print) sis, charac aptobenzo Faisal Mahd Pharmaceutical Ch g author at: Depart 5514340. Fax: +964 FORMATION eurjchem.7.1.8‐13. ctober 2015 vised form: 06 Nov ovember 2015 ne: 31 March 2016 rch 2016 S hod nonitrile tion ave‐assisted or eleration of e of three‐dim h cannot be gh yields, impr e additional adv er, even reactio ng can be perfo es, microwave ques represent o conventional ptobenzothiazo ous biological a microbial [5‐9 ], carbonic an ageal reflux di aryl‐3‐substitut ntermediates in exhibits wides ibacterial, antif [15], anticance / ISSN 2153‐225 h Europ cterizatio othiazole i *, Rafah Fa emistry, College of tment of Pharmace 4.770.5514340. E‐m 1333 ember 2015 rganic synthes many chemic mensional heat reproduced b oved selectivity vantages of this ons that do not ormed with mi irradiation co ts a powerful, synthesis [2]. ole derivative activities such a 9], anticancer nhydrase inhi isease and ant ted‐5‐pyrazolon n the synthesis spread pharma fungal [13] ant r [16] and anti European Journ Europ 57 (Online)  20 http://dx.doi.org pean Jo Journal web n and ant derivativ adhil Al‐Sma f Pharmacy, Al‐Mus eutical Chemistry, C mail address: dr.mon ABSTRACT An efficient m derivatives (6 irradiation. Th of heterocycli Chalcones int the result con one. The syn Antibacterial types of bacte Cite this: Eur. sis results in cal reactions ing of the rea by classical he y, and clean rea s synthetic tech t occur with co icrowave irradi oupled with so eco‐friendly, es are know as anti‐inflamm [10], anthelm bitor, treatme tihypertensive ne derivatives of biologically acological prop ti‐inflammatory itubercular act nal of Chemistry pean Journal of C 016 Atlanta Pub g/10.5155/eurjc ournal bpage: www. tibacteria ves bearin aism and No tansiriyah Universi College of Pharmacy nther.f71@uomust methods has be 6a‐f) bearing be he reaction proc ic methyl keton ermediate and f nfirms that micro thesized compo activities of the eria; most of the . J. Chem. 2016, spec‐ as a action eating action hnique onven‐ iation. olvent‐ green wn to matory mintic ent of effect s are active perties y [14], ivities (2‐a an i the dive [18 infl the pre thes mer con var clas field forw acti nitr anti 2. E 2.1. 7 (1) (2016) 8‐1 Chemistry lishing House LL chem.7.1.8‐13.13 of Che .eurjchem.co al evaluati ng 2‐amin oor Waleed I ity, Baghdad, 1000 y, Al‐Mustansiriyah tansiriyah.edu.iq (M een described f enzothiazole nu ceeds via one‐po nes (4a), malono final compounds owave method s ounds were cha synthesized com tested compoun 7(1), 8‐13 A literature s amino‐3‐cyanop important grou subject of exte erse biological ], anticancer ammatory and The developm means for tr viously had be se widespread rcaptobenzothi ntaining compo iety of antiba sses, resistance d must respon ward stream o ivity against ba Our goal is to rile and prelim ibacterial agent Experimental . Reagents and 13 LC ‐ All rights re 333 emistry m ion of nov nonicotino Ibrahim 01, Iraq h University, Baghd M.F. Mahdi). for the synthesi ucleus by solven ot four‐compone onitrile, ammon s were also synth showed higher y aracterized by F mpounds have b nds showed sign urvey revealed pyridine) nucle up of heterocycl ensive study in activities, such activity [19], analgesic activ ent of new and reating resistan een susceptible applications an iazole, pyrazolo ounds and in s cterial agents e continues to nd to these cli of new agents cteria [23]. synthesis new minary pharm ts. d chemistries served ‐ Printed y vel onitrile m dad, 10001, Iraq. is of new 2‐am nt free microwa nt by cyclo cond nium acetate an hesized by conve yield and purity t FT‐IR spectrosco been tested agai ificant biologica d that 2‐amino eus derivatives lic compounds n the recent pas h as: antibacte antituberculos vities [21]. different antib nt strains of o e to an older a nd biological sig one and amino pite of the int in multiple u emerge. The p inical challenge with promisin analogues of 2‐ macological eva d in the USA moiety minonicotinonitri ave or ultrasoun densation reactio d aryl aldehyde entional method than convention opy and 1H NM inst four differe al activities. onicotinonitrile s belonging to that have been st. It possesses erial, antifungal sis [20], anti‐ biotics provided organisms that antibiotic [22], gnificance of 2‐ onicotinonitrile troduction of a unrelated drug pharmaceutical es by bringing ng antibacterial ‐aminonicotino aluated as an ile nd on es. ds, nal R. nt e o n s l ‐ d t , ‐ e a g l g l o n Mahdi et al. / European Journal of Chemistry 7 (1) (2016) 8‐13 9 S N S N S N N N S N N N S N N N S N N N SH NH O CH3 O H3C O C C N NH2 CH3 O CH3 CN H2N O O NH2NH2.H2O Ca(OH)2/1,4-dioxane CH3 Cl O X X H3C OCH2CH3 O O 2a CH3 3a 4a H H Conventional method X H O X H O NC CN , , NH4OAc NC CN 5a-f 6a-f Microwave or Ultrasound method Conventional method 1a NH4OAc Compound : 6a 6b 6c 6d 6e 6f X : H Cl N(CH3)2 OH OCH3 NO2 S N N N CH3 HO H3C O Scheme 1 All reagents and solvents were of analytical grade. All solvents were freshly distilled under anhydrous conditions. Microwave reactor (Anton Paar, USA) and Ultrasonic (ELMA) were used as reactor. Melting points were determined by open capillary method on Stuart/Electrothermal an electric melting point apparatus (U.K.) and ascending thin layer chromato‐ graphy (TLC) to check the purity and progress of reactions was run on silica gel (60) F254, Merck (Germany). The identification of compounds was done using a U.V. detector and the chromatograms were eluted with ethylacetate: chloroform (4:6, v:v). IR spectra were recorded on a FT‐IR spectrophotometer Shimadzu as KBr disks. 1H NMR spectra were recorded using DMSO‐d6 as solvent and TMS as internal standard on a Bruker (400 MHz) spectrometer (Chemical shifts represented in δ, ppm). The general routes outlined in Scheme 1 were used to synthesize all compounds. 2.2. General procedure for synthesis of 2‐hydrazinylbenzo [d]thiazole (2a) 2.2.1. Microwave method 2‐Hydrazinylbenzo[d]thiazole (2a) was prepared by microwave method as per the reported earlier [8]. 2.2.2. Ultrasound method 2‐Hydrazinylbenzo[d]thiazole (2a) was prepared by ultrasound methods as per the reported earlier [24]. 2.3. General procedure for synthesis of 1‐(benzo[d]thiazol‐ 2‐yl)‐3‐methyl‐1H‐pyrazol‐5(4H)‐one (3a) 2.3.1. Conventional method Ethyl acetoacetate (0.005 mol, 0.656 g) was added dropwise to 2‐hydrazinobenzothiazole (2a) (0.005 mol, 0.825 g) in round bottom flask with constant stirring at room temperature for 15 min. A precipitate formed quickly. The reaction mixture was poured on crushed ice. The solid was separated, filtered and dried. Compound 3a was recrystallized from ethanol [25]. Color: Deep orange to yellow. Yield: 83%. M.p.: 150‐152 °C. FT‐IR (KBr, , cm‐1): 3078 ν(CH, aromatic), 2964 ν(CH, aliphatic), 1737 ν(C=O, pyrazolone), 1649 ν(C=N), 1614 ν(C=C, aromatic). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.95 (s, 3H, CH3), 3.45 (s, 2H, CH2), 7.28‐7.32 (t, 2H, Ar‐H), 7.37‐7.41 (d, 1H, Ar‐H), 7.60 (d, 1H, Ar‐H). 10 Mahdi et al. / European Journal of Chemistry 7 (1) (2016) 8‐13 2.3.2. Microwave method Ethyl acetoacetate (0.005 mol, 0.656 g) was added dropwise to corresponding 2‐hydrazinobenzothiazole (2a) (0.005 mol, 0.825 g), the mixture was irradiated with microwave (300 W) for 4 min. The cold reaction mixture was treated with ethanol. The solid product was filtered, dried (the solid obtained was recrystallized from ethanol) [26]. Yield: 85%. 2.3.3. Ultrasound method A solution of 2‐hydrazinobenzothiazole (2a) (0.005 mol, 0.825 g) in ethanol (1 mL) was added dropwise to the corresponding ethyl acetoacetate (0.005 mol, 0.656 g) contained in a 25 mL conical flask. The mixture was irradiated in the water bath of an ultrasonic cleaner for 25 min. The cold reaction mixture was treated with ethanol. The solid product was filtered and dried. The solid obtained was recrystallized from ethanol [26]. Yield: 68%. 2.4. Synthesis of 4‐acetyl‐1‐(benzo[d]thiazol‐2‐yl)‐3‐methyl‐ 1H‐pyrazol‐5(4H)‐one (4a) The acylation reaction of compound 3a was prepared as the reported method [27] and purified by recrystallization. Keto‐form (Major tautomer): Color: Colourless. Yield: 75%. M.p.: 161‐163 °C. 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 7.78‐ 7.83 (d, 2H, Ar‐H), 7.60‐7.71 (t, 2H, Ar‐H), 3.73 (s, 1H, CH), 2.93 (s, 3H, CH3), 1.95 (s, 3H, CH3). FT‐IR (KBr, , cm‐1): 3236 ν(broad, OH), 3063 ν(C‐H, aromatic), 2956, 2926 ν(C‐H, aliphatic), 1748 ν(C=O, ketone), 1727 ν(C=O, pyrazolone), 1637 ν(C=N), 1602 ν(C=C, aromatic), 1365 ν(C‐CH3). Enol‐form (Minor tautomer): Color: Yellow. Yield: 25%. M.p.: 173‐176 °C. 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 12.7 (s, 1H, OH), 7.36‐ 7.68 (d, 2H, Ar‐H), 7.25‐7.32 (t, 2H, Ar‐H) , 3.55 (s, 3H, CH3), 1.96 (s, 3H, CH3). 2.5. Synthesis (E)‐1‐(benzo[d]thiazol‐2‐yl)‐4‐(3‐(4‐(substi‐ tuted)phenyl)acryloyl)‐3‐methyl‐1H‐pyrazol‐5(4H)‐one as chalcone derivatives (5a‐f) 4‐Acetyl‐1‐(benzo[d]thiazol‐2‐yl)‐3‐methyl‐1H‐pyrazol‐5 (4H)‐one (4a) (0.0037 mol, 1 g) was dissolved in 10 mL of ethanol in a round bottomed flask followed by (0.0037 mol) of p‐substituted aromatic aldehyde and 4 drops of piperidine were added dropwise within 5 min. The mixture heated for 6 hours at 65 °C. The reaction mixture was cooled; the solid product was collected by filtration, washed with water and recrystallized from ethanol [28]. (E)‐1‐(1‐(benzo[d]thiazol‐2‐yl)‐5‐hydroxy‐3‐methyl‐1H‐ pyrazol‐4‐yl)‐3‐phenylprop‐2‐en‐1‐one (5a): Color: Deep brown. Yield: 65%. M.p.: 89‐91 °C. FT‐IR (KBr, , cm‐1): 3406 ν(OH), 3059 ν(Ar‐H), 2918 ν(aliphatic, CH), 1705 ν(C=O, pyrazolone), 1695 ν(α,β‐unsaturated ketone), 1633 ν(C=N), 1616 ,1518 ν(C=C, Ar). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.56 (s, 3H, CH3), 6.79 (d, 1H, ‐CH=), 6.89 (d, 1H, =CH‐Ar), 7.40‐ 7.96 (m, 7H, Ar‐H), 8.28 (d, 2H, Ar‐H), 9.60 (s, 1H, OH). (E)‐1‐(Benzo[d]thiazol‐2‐yl)‐4‐(3‐(4‐chlorophenyl)acryloyl)‐ 3‐methyl‐1H‐pyrazol‐5(4H)‐one (5b): Color: Deep gray. Yield: 67%. M.p.: 91‐93 °C. FT‐IR (KBr, , cm‐1): 3482 ν(OH), 3037 ν(ArH), 2960 ν(aliphatic, CH), 1710 ν(C=O, pyrazolone), 1696 ν(α,β‐unsaturated ketone), 1619 ν(C=N), 1599, 1590 ν(C=C, Ar), 752 ν(C‐Cl). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.89 (s, 3H, CH3), 3.30 (s, 1H, CH pyrazolone), 6.76 (d, 1H, ‐CH=), 7.48 (d, 1H, =CH‐Ar), 7.48‐7.52 (d, 2H, Ar‐H), 7.59‐7.63 (d, 2H, Ar‐ H), 7.69‐7.78 (m, 2H, Ar‐H) , 8.29 (d, 2H, Ar‐H). (E)‐1‐(1‐(benzo[d]thiazol‐2‐yl)‐5‐hydroxy‐3‐methyl‐1H‐ pyrazol‐4‐yl)‐3‐(4‐(dimethylamino)phenyl)prop‐2‐en‐1‐one (5c): Color: Red. Yield: 80%. M.p.: 249‐252 °C. FT‐IR (KBr, , cm‐1): 3320 ν(OH), 3061 ν(ArH), 2912, 2821 ν(aliphatic, CH), 1715 ν(C=O, pyrazolone), 1677 ν(α,β‐unsaturated ketone), 1662 ν(C=N), 1600, 1550 ν(C=C, Ar), 1375 ν(N‐CH3). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.64 (s, 3H, CH3), 3.03 (s, 6H, ‐N(CH3)2), 6.06 (d, 1H, ‐CH=), 6.79 (d, 2H, Ar‐H), 7.15 (d, 1H, =CH‐Ar), 7.20‐7.32 (d, 2H, Ar‐H), 7.42(d, 2H, Ar‐H), 8.08‐8.18 (d, 2H, Ar‐H), 10.07 (s, 1H, OH). (E)‐1‐(1‐(benzo[d]thiazol‐2‐yl)‐5‐hydroxy‐3‐methyl‐1H‐ pyrazol‐4‐yl)‐3‐(4‐hydroxyphenyl)prop‐2‐en‐1‐one (5d): Color: Deep gray. Yield: 70%. M.p.: 97‐100 °C. FT‐IR (KBr, , cm‐1): 3416 ν(OH), 3063 ν(ArH), 2953 ν(aliphatic, CH), 1714 ν(C=O, pyrazolone), 1688 ν(α,β‐unsaturated ketone), 1612 ν(C=N), 1588, 1515 ν(C=C, Ar), 1246 ν(C‐O, phenolic). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.61 (s, 3H, CH3), 6.62 (d, 2H, Ar‐H), 6.89 (d, 1H,‐CH=), 7.38 (d, 1H, =CH‐Ar), 7.47‐7.53(d, 2H, ArH), 7.59‐7.64 (d, 2H, Ar‐H), 7.80‐7.82 (d, 2H, Ar‐H), 9.55 (s, 1H, OH). (E)‐1‐(Benzo[d]thiazol‐2‐yl)‐4‐(3‐(4‐methoxyphenyl) acryl oyl)‐3‐methyl‐1H‐pyrazol‐ 5(4H)‐one (5e): Color: Brown. Yield: 69%. M.p.: 84‐86 °C. FT‐IR (KBr, , cm‐1): 3072 ν(ArH), 2960 ν(aliphatic, CH), 1710 ν(C=O, pyrazolone), 1690 ν(α,β‐ unsaturated ketone), 1633 ν(C=N), 1600, 1577 ν(C=C, aro‐ matic), 1249 ν(OCH3). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.55 (s, 3H, CH3), 3.69 (s, 1H, CH pyrazolone), 3.81 (s, 3H, OCH3), 6.70 (d, 1H, ‐CH=) 6.89 (m, 2H, Ar‐H), 7.14 (d, 1H, =CH‐ Ar), 7.33‐7.58 (d, 2H, ArH), 7.65‐7.84 (m, 4H, Ar‐H). (E)‐1‐(Benzo[d]thiazol‐2‐yl) ‐3‐methyl‐4‐(3‐(4‐nitrophenyl) acryloyl)‐1H‐pyrazol‐5(4H)‐one (5f): Color: Deep yellow. Yield: 75%. M.p.: 182‐184 °C (Dec.). FT‐IR (KBr, , cm‐1): 3369 ν(OH), 3063 ν(ArH), 2931 ν(aliphatic, CH), 1705 ν(C=O, pyrazolone), 1679 ν(α,β‐unsaturated ketone), 1633 ν(C=N), 1600, 1519 ν(C=C, aromatic), 1489, 1344 ν(NO2). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.53‐1.59 (s, 3H, CH3), 3.35‐3.39 (s, 1H, CH of pyrazolone), 7.18 (d, 1H, ‐CH=), 7.57‐7.85 (m, 4H, Ar‐H), 8.13‐8.18 (d, 1H, =CH‐Ar), 8.37‐8.41 (d, 2H, Ar‐H), 8.87 (d, 2H, Ar‐H). 2.6. Synthesis of 2‐amino‐6‐(1‐(benzo[d]thiazol‐2‐yl)‐3‐ methyl‐5‐oxo‐4,5‐dihydro‐1H‐pyrazol‐4‐yl)‐4‐((4‐subsiti‐ tuted)phenyl) nicotinonitrile as aminonicotinonitrile (6a‐f) 2.6.1. Conventional method To a solution of chalcone (5a‐f) (0.01 mol) in 5 mL ethanol, (0.01 mol, 0.12 g) malononitrile and (0.03 mol, 0.398 g) ammonium acetate were added. Reaction mixture was refluxed at 60 °C for 8 hours, poured into crushed ice water, the product was extracted with 20 mL ethyl acetate. The organic layer was washed with brine, dry over sodium sulphate and evaporated under reduced pressure [29]. 2.6.2. Ultrasound method A mixture of equimolar (0.00075 mol) of malononitrile, substituted aromatic aldehydes and 4‐acetyl‐1‐(benzo[d] thiazol‐2‐yl)‐3‐methyl‐1H‐pyrazol‐5(4H)‐one (4a) ammonium acetate and water (5 mL). The reaction mixture irradiated in ultrasonic bath for 18‐30 min at 50 °C. The reaction was monitored by TLC. Reaction mixture was diluted with water (10 mL), filtered, washed with water and dried to give crude product, and recrystallized from ethanol [30]. 2.6.3. Microwave method A mixture of equimolar (0.00075 mol) of 4‐acetyl‐1‐ (benzo[d]thiazol‐2‐yl)‐3‐methyl‐1H‐pyrazol‐5(4H)‐one (4a) substituted aromatic aldehydes, malononitrile and ammonium acetate (0.0011 mol, 0.085 g) was irradiated by the microwave (7‐9 min, 50 °C, 300 W). Reaction mixture was washed with ethanol. The crude products were recrystallized from ethanol [31]. Mahdi et al. / European Journal of Chemistry 7 (1) (2016) 8‐13 11 2‐Amino‐6‐(1‐(benzo[d]thiazol‐2‐yl)‐3‐methyl‐5‐oxo‐4,5‐ dihydro‐1H‐pyrazol‐4‐yl)‐4‐phenylnicotinonitrile (6a): Color: Dark brown. Yield: 62% (A), 41% (B), 68% (C). M.p.: 160‐163 °C. FT‐IR (KBr, , cm‐1): 3331, 3310 ν(NH2), 3059 ν(ArH), 2926 ν(aliphatic, CH), 2191 ν(CN), 1712 ν(C=O, pyrazolone), 1631 ν(C=N). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 2.08 (s, 3H, CH3), 3.84‐3.89 (s, 1H, ‐CH for methine), 6.98 (s, 1H, CH, 2‐Pyridine), 7.30‐7.72 (m, 7H, Ar‐H), 7.80‐7.99 (d, 2H, Ar‐H), 8.405 (broad s, 2H, NH2). 2‐Amino‐6‐(1‐(benzo[d]thiazol‐2‐yl)‐3‐methyl‐5‐oxo‐4, 5‐dihydro‐1H‐pyrazol‐4‐yl)‐4‐(4‐chlorophenyl) nicotinonitrile (6b): Color: Redish brown. Yield: 66% (A), 43% (B), 69% (C). M.p.: 107‐108 °C. FT‐IR (KBr, , cm‐1): 3336, 3279 ν(NH2), 3059 ν(ArH), 2974 ν(aliphatic, CH), 2171 ν(CN), 1714 ν(C=O, pyrazolone), 1629 ν(C=N), 1055 ν(C‐Cl). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 2.11(s, 3H, CH3), 3.50‐3.53 (s, 1H, ‐C‐H for methine), 7.13 (s, 1H, CH, 2‐Pyridine), 7.46‐7.53 (d, 2H, Ar‐H), 7.55‐7.68 (m, 4H, Ar‐H), 7.84 (d, 2H, Ar‐H), 8.671 (broad s, 2H, NH2). 2‐Amino‐6‐(1‐(benzo[d]thiazol‐2‐yl)‐3‐methyl‐5‐oxo‐4, 5‐ dihydro‐1H‐pyrazol‐4‐yl)‐4‐(4‐(dimethylamino)phenyl) nicotine nitrile (6c): Color: Yellow. Yield: 78% (A), 54% (B), 85% (C). M.p.: 128‐130 °C. FT‐IR (KBr, , cm‐1): 3317, 3232 ν(NH2), 3082 ν(ArH), 2947 ν(aliphatic, CH), 2210 ν(CN), 1707 ν(C=O, pyrazolone), 1620 ν(C=N), 1371 ν(N‐CH3). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.84 (s, 3H, CH3), 3.11 (s, 6H, ‐N(CH3)2), 3.76 (s, 1H, CH for methine), 6.63 (d, 2H, Ar‐H), 7.09 (s, 1H, ‐CH for 2‐Pyridine), 7.39 (d, 2H, Ar‐H), 7.67‐8.12 (m, 4H, Ar‐H), 8.671 (broad s, 2H, NH2). 2‐Amino‐6‐(1‐(benzo[d]thiazol‐2‐yl)‐3‐methyl‐5‐oxo‐4, 5‐ dihydro‐1H‐pyrazol‐4‐yl)‐4‐(4‐hydroxyphenyl) nicotinonitrile (6d): Color: Deep brown. Yield: 67% (A), 46% (B), 73% (C). M.p.: 138‐140 °C. FT‐IR (KBr, , cm‐1): 3373, 3295 ν(NH2), 3061 ν(ArH), 2949 ν(aliphatic, CH), 2216 ν(CN), 1709 ν(C=O, pyrazolone), 1614 ν(C=N). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 2.22 (s, 3H, CH3), 3.71 (s, 1H, CH methine), 6.61‐6.79 (d, 2H, Ar‐H), 7.09 (s, 1H, ‐CH, 2‐Pyridine), 7.67‐7.70 (m, 4H, Ar‐ H), 7.86 (d, 2H, Ar‐H), 8.42 (broad s, 2H, ‐NH2), 9.07 (broad s, 1H, OH). 2‐Amino‐6‐(1‐(benzo[d]thiazol‐2‐yl)‐3‐methyl‐5‐oxo‐4, 5‐ dihydro‐1H‐pyrazol‐4‐yl)‐4‐(4‐methoxyphenyl) nicotinonitrile (6e): Color: Brown. Yield: 68% (A), 53% (B), 75% (C). M.p.: 132‐134°C. FT‐IR (KBr, , cm‐1): 3444, 3420 ν(NH2), 3028 ν(ArH), 2933 ν(aliphatic, CH), 2222 ν(CN), 1701 ν(C=O, pyrazolone), 1635 ν(C=N), 1250 ν(OCH3). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 2.09 (s, 3H, CH3), 3.03 (s, 1H, CH methine), 3.84‐3.89 (s, 3H, OCH3), 6.98 (d, 2H, Ar‐H), 7.12‐7.18 (s, 1H, 2‐ Pyridine), 7.33‐7.72 (m, 4H, Ar‐H), 7.97 (d, 2H, Ar‐H), 8.55 (broad s, 2H, NH2). 2‐Amino‐6‐(1‐(benzo[d]thiazol‐2‐yl)‐3‐methyl‐5‐oxo‐4, 5‐ dihydro‐1H‐pyrazol‐4‐yl)‐4‐(4‐nitrophenyl) nicotinonitrile (6f): Color: Faint orange. Yield: 72% (A), 55% (B), 76% (C). M.p.: 227‐229 °C (Dec.). FT‐IR (KBr, , cm‐1): 3358, 3277 ν(NH2), 3064 ν(ArH), 2929 ν(aliphatic, CH), 2218 ν(CN), 1719 ν(C=O, pyrazolone), 1636 ν(C=N), 1521, 1346 ν(NO2). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 1.61 (s, 3H, CH3), 2.98 (s, 1H, CH methine), 7.23 (s, 1H, 2‐Pyridine), 7.56‐7.86 (m, 4H, Ar‐H), 8.13‐8.18 (d, 2H, Ar‐H), 8.20‐8.26 (d, 2H, Ar‐H), 8.35 (broad s, 2H, NH2). 2.7. Pharmacology 2.7.1. Antimicrobial activity [32] A preliminary antibacterial activity has been carried out according to Well Diffusion Method [33]: The antimicrobial activity of synthesized compounds have been studied in‐vitro against four types of bacteria (Staphylococcus aureus and Streptococcus Pneumoniae as Gram positive bacteria, Klebsiella pneumoniae and Pseudomonas aeruginosa as Gram negative bacteria) obtained from laboratories of Department of Biology, College of Science, Al‐Mustansiriyah University were clinical activated and maintained on nutrient agar medium. Type of media used: Mueller‐Hinton agar for testing antibacterial activity. Ciprofloxacin and ceftriaxone were used as standard drugs for antibacterial activity. Tested compounds were dissolved in dimethylsulphoxide (DMSO) to give final four different concentrations of 500, 250, 125 and 62.5 μg/mL. 2.7.2. Sensitivity assay Well diffusion assay was carried out by using bacterial suspension (1.5×108 CFU/mL) obtained from McFarland turbidity standard (number 0.5) [34]. This was used to inoculate by swabbing the surface of Mueller‐Hinton agar (MHA) plates. The excess liquid was air‐dried under a sterile hood. In each agar plate of tested bacteria five wells were made and (100 μL) of each concentration was added in it. The plates were transferred to be incubated at 37 °C for 24 hours. 3. Results and discussion 5‐Pyrazolones (3a) was synthesized by cyclocondensation of compound 2a with ethyl acetoacetate using conventional, microwave and ultrasound methods. 4‐Acetyl‐1‐(benzo[d] thiazol‐2‐yl)‐3‐methyl‐1H‐pyrazol‐5(4H)‐one (4a) was synthe‐ sized by the acylation of compound 3a with the corresponding acid chloride following Jensen’s procedure and are good crystallizing compounds often obtainable both in the keto form by recrystallization from polar solvents as alcohol‐water or dioxane‐water mixtures, and in the enol form by recrystal‐ lization from non polar solvent as chloroform. [27]. The chalcone derivatives, (E)‐1‐(benzo[d]thiazol‐2‐yl)‐4‐ (3‐(4‐(substituted) phenyl)acryloyl)‐3‐methyl‐1H‐pyrazol‐ 5(4H)‐one as chalcone derivatives (5a‐f) were synthesized by reacting compound 4a with different substituted aromatic aldehydes by using ammonium acetate in ethanol. Finally, the compounds 5a‐f were reacted with malononitrile to give corresponding compound 6a‐j in good yields. The synthesized compounds were characterized by FT‐IR and 1H NMR techniques. The IR spectrum of chalcones (5a‐f) exhibited characteristic band absorption for α,β‐unsaturated ketone group in the region of 1677‐1696 cm‐1. The absorptions bands at around 1588‐1616 cm‐1 were assigned to the existing of conjugated C=C. The aldole condensation of the final compounds (6a‐f) exhibited very similar features and showed the expected bands for the characteristic groups which are present in the compounds, such as NH2 and the CN stretching vibrations is an evidence of ring closure; it showed the appearance of multiple bands in at 3232 and 3444 cm‐1 range due to stretching vibrations of NH2 group, the spectrum exhibited characteristic new absorption band at 2171‐2222 cm‐1 range were assigned to stretching vibrations of CN group. In the proton NMR spectral data, all protons were seen according to the expected chemical shift and integral values. The aromatic protons appeared as multiplet peaks within the range δ 7.00‐7.80 ppm. Singlet signals derived from ‐NH2 and Ar‐H of pyridine ring (6a‐f) structure appeared at δ 8.40‐9.07 and 6.97‐7.09 ppm, respectively. The reaction may proceed via imine formed from aldehyde and ammonium acetate, imine reacts with alkylidene malononitrile (from condensation of aromatic aldehyde with malononitrile) to give the following intermediate, carry on by cycloaddition, isomerization, aromatization to afford the 2‐ amino‐3‐cyanopyridine. Bacterial growth and the antibacterial activity was evaluated by measuring the diameter of the inhibition zone (IZ) around the well in mm, and show that the zone of inhibition increased with the increasing of concentration of the tested compounds (Table 1). 12 Mahdi et al. / European Journal of Chemistry 7 (1) (2016) 8‐13 Table 1. Antibacterial screening data (zone of inhibition in mm) for final compounds 6a‐f, 2‐MBT, ciprofloxacin and ceftriaxone. Compound R Conc. (µg/mL) Inhibition zone (mm) Staphylococcus aureus Streptococcus Pneumoniae Klebsiella Pneumoniae Pseudomonas aeruginosa 6a H 500.0 15 20 20 16 250.0 14 18 17 16 125.0 13 17 15 15 62.5 11 17 13 13 6b Cl 500.0 13 14 12 13 250.0 11 11 13 11 125.0 10 10 10 12 62.5 10 10 10 ‐ 6c N(CH3)2 500.0 19 11 ‐ 12 250.0 18 11 12 11 125.0 17 10 ‐ 11 62.5 13 9 10 10 6d OH 500.0 11 20 18 ‐ 250.0 ‐ 13 16 ‐ 125.0 ‐ 12 14 ‐ 62.5 10 10 13 ‐ 6e OCH3 500.0 ‐ 20 11 13 250.0 ‐ 15 10 12 125.0 10 16 ‐ 10 32.5 10 10 ‐ 10 6f NO2 500.0 11 16 11 11 250.0 ‐ 14 ‐ 10 125.0 ‐ 12 ‐ 10 62.5 9 10 9 ‐ 2‐MBT 500.0 ‐ 13 15 13 250.0 ‐ 12 10 13 125.0 ‐ 11 10 12 62.5 ‐ 11 10 10 Ciprofloxacin 500.0 25 29 32 22 250.0 25 28 34 19 125.0 25 20 30 18 62.5 25 15 29 13 Ceftriaxone 500.0 32 26 10 20 250.0 28 19 ‐ 19 125.0 24 17 10 14 62.5 24 16 4 9 DMSO Pure ‐ ‐ ‐ ‐ All tested compounds exert significant antibacterial activity in comparison to DMSO as control group and an interesting activity against gram positive Staphylococcus aureus unlike the parent compound. In comparison to standard compound (ciprofloxacin), tested compound show lower activity against all tested bacterial species. While for the standard compound (ceftriaxone) the tested compounds showed better activity against Klebsiella Pneumoniae and lower antibacterial effect against the other three species. Finally compound 6a derivative may regard the best one generally and the nitrobenzene (6f) was the least one. 4. Conclusion The area of the synthesis of some novel 2‐amino nicotinonitrile ring derivatives continues to grow, and better methods were developed for the synthesis of these interesting heterocycles to allow the discovery of new drug candidates. The advantages of microwave irradiation under solvent free condition method are high yields, relatively short reaction times, low cost and simple experimental. Various new derivatives of 2‐amino‐6‐(1‐(benzo[d]thiazol‐ 2‐yl)‐3‐methyl‐5‐oxo‐4,5‐dihydro‐1H‐pyrazol‐4‐yl)‐4‐((4‐sub‐ sitituted)phenyl) nicotinonitrile (6a‐f) were synthesized and screened for antibacterial activity, most of these compounds show good antimicrobial activity comparable with marketable compounds and among them hydroxy containing derivative is the only one which exhibited no antibacterial activity against Pseudomonas aeruginosa and benzaldehyde derivative is the best one against Klebsiella pneumonia. Acknowledgements The authors would like to express their deepest gratitude to Al Mustansiriyah Pharmacy College in Baghdad, Iraq for funding and giving permission to access to their laboratory in order to conduct this research work. We would also like to acknowledge the support received from assistant Prof. Ali Hussein Alwan while conducting the research work. References [1]. Singh, V.; Kumar, P.; Sanghi, R. Prog. Polym. Sci. 2012, 37, 340‐364. [2]. 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