Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 4(12), 42-47, December (2014) Res. J. Chem. Sci.International Science Congress Association 42 Microwave Induced Synthesis of New Fused Oxazole Dabholkar Vijay V *, Mustaqeem Mohammed A, Shinde Navnath.B and Yadav Omprakash G Organic Research Laboratory, Department of Chemistry, Guru Nanak College, G.T.B Nagar, Mumbai-400 037, INDIAAvailable online at: www.isca.in, www.isca.me Received 15th November 2014, revised 8th December 2014, accepted 15th Decmeber 2014 AbstractAn easy, efficient and novel method for the synthesis of 7-(substituted phenyl)-2-thiophene-2-yl-7H-oxazolo[3,2-a]pyridine-5-ol (4) and 7-( substituted phenyl)-2-pheneyl-7H-oxazolo[3,2-a]pyridine-5-ol (5). Representative samples were screened for their anti-microbial activity against Gram- positive bacteria, Gram-negative bacteria, fungi and yeast by using disc diffusion method. All the physico- chemical tests as well as spectral technique are used for confirmation of structure of targeted molecule. Keywords:-Bromoacetothiophenone, -Bromoacetophenone, Fused Oxazoles and Green method. IntroductionThe study of heterocyclic chemistry and compound play very important role in organic field. Substituted oxazole derivatives synthesis is particularly important because of compounds involving the oxazole ring system are known to have diverse range of biological activities in pharmaceutical areas. Oxazoles are continued to be of interest for both their biological activities and synthetic utility3-6. The synthesis of aryl-oxazoles is also the subject of on-going improvements7-8. It is worth mentioning that a combination of a heterocycles moiety fused with a piperidine ring may increase their biological activities or create new medicinal properties due to the different electronic distribution9-10. Oxazole derivatives apply as pesticides, fluorescent whitening agents, lubricants, dyes and pigments11-13. Microwave-induced eco-friendly synthesis of organic compound has become a new facilitated area in synthesizing organic molecule. Chemical reactions which are conducted under the microwave irradiation have many advantages as compared to the conventional method involving very high temperature14. Material and Methods Experimental: Physical constant of all synthesized compounds were determined in open capillary tubes on an electro thermal digital apparatus. The conversion of starting material checked by using thin layer chromatography on silica gel coated aluminum plates (Merck) as adsorbent and UV chamber as visualizing agent. H and 13CNMR spectra were recorded on Varian 600 MHz NMR spectrophotometer using DMSO-d as solvent and TMS as reference (chemical shifts in ppm). C, H, N analysis was recorded on Carlo Erba 1108 (CHN) Elemental Analyzer. Representative procedure for synthesis of(4a): A mixture of 4-phenyl-pyperidine—4,6-dione(0.01 mol), KCO3 (0.02 mol), -Bromoacetothiophenone (2) (0.01 mol) and DMF (0.025 mol), was irradiated in micro-wave. The conversion of starting material checked on TLC. Upon completion, the reaction mass was quenched into ice-cold water. The solid thus generated, was filtered, washed and recrystallised from ethanol to get 7- phenyl-2-thiophene-2-yl-7H-oxazolo[3,2-a]pyridine-5-ol (4a).Representative procedure for synthesis of(5a): A mixture of 4-phenyl-pyperidine—4,6-dione(0.01 mol), KCO3 (0.02 mol), -Bromoacetophenone (3) (0.01 mol) and DMF (0.025 mol), was irradiated in micro-wave. The conversion of starting material checked on TLC. Upon completion, the reaction mass was quenched into ice-cold water. The solid thus generated, was filtered, washed and recrystallised from ethanol to get 2,7-diphenyl-7H-oxazolo[3,2-a]pyridine-5-ol (5a).Spectral Interpretation: 7-(4-Methoxy phenyl)-2-thiophene-2-yl-7H-oxazolo[3,2-a]pyridine-5-ol (4c) Yield: 78%; m.p.=130-132°C: IR (cm-1): 3200 (OH), 1100 (C-O), H NMR (DMSO-d6, / ppm): 3.79 (s, 3H, OCH), 4.7 (t, 1H, CH), 5.2 (s, 1H,= CH), 5.32 (s, 1H,= CH), 5.5 (s, 1H,= CH), 6.80-8.20 (m, 7H, Ar -H), 10.90 (s, 1H, OH), 13C NMR (DMSO-d6, / ppm): 30 (CH), 56.14 (OCH), 74 ( =CH), 75.14 (=CH), 115.5- 148.0 (Ar-C and C=C), 158.41 (=C-OH). LCMS; m/z: 325; Analytical calculation for C1815NO: C, 66.46; H, 4.61; N, 4.53; S, 10.35% Found C, 66.51; H, 4.42; N, 4.23; S, 10.15%. 7- (4-Hydroxy-3-methoxy phenyl) -2-thiophene-2-yl -7H-oxazolo [3,2-a]pyridine-5-ol (4e): Yield: 85%; m.p. =145-148°C: IR (cm-1): 3200 (OH), 1100 (C-O), H NMR (DMSO-d6, / ppm): 3.76 (s, 3H, OCH), 4.71 (t, 1H, CH), 5.2 (s, 1H,= CH), 5.32 (s, 1H,= CH), 5.6 (s, 1H,= CH), 5.3 (s, 1H, CH), 5.6 (s, 1H, OH), 6.80-8.20 (m, 7H, Ar -H), 8.90 (s, 1H, OH), 13C NMR (DMSO-d6, / ppm): 31 (-CH), 56.14 (OCH), 75.0 ( =CH), 76.15 (=CH), 115.5- 148.0 (Ar-C and C=C), 157.40 (=C-OH). LCMS; m/z: 341; Analytical calculation for 1815NOS: C, 63.34; H, 4.39; N, 4.10 % Found C, 63.52; H, 4.42; N, 4.03%. Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(12), 42-47, December (2014) Res. J. Chem. Sci.International Science Congress Association 43 7-(4-Methoxy phenyl)-2-phenyl-7H-oxazolo[3,2-a]pyridine-5-ol (5c): Yield: 80%; m.p. =166°C: IR (cm-1): 3200 (OH),1100 (C-O), H NMR (DMSO-d6, / ppm): 3.76 (s, 3H, OCH), 4.72 (t, 1H, CH), 5.20 (s, 1H,= CH), 5.30 (s, 1H,= CH), 5.4 (s, 1H, CH), 6.80-7.3.20 (m, 9H, Ar -H), 9.95 (s, 1H, OH), 13C NMR (DMSO-d6, / ppm): 34 (-CH), 32 ( =CH), 56.14 (OCH), 77.0 ( =CH), 78.20 (=CH), 115.5- 148.0 (Ar-C and C=C), 157.40 (=C-OH). LCMS; m/z: 319; Analytical calculationfor C2017N0: C, 75.23; H, 5.32; N, 4.38 % Found C, 75.33; H, 5.28; N, 4.47 %.7-(4-Hydroxy phenyl)-2-phenyl-7H-oxazolo[3,2-a]pyridine-5-ol (5d): Yield: 70%; m.p. =126-127°C: IR (cm-1): 3200(OH), 1100 (C-O), H NMR (DMSO-d6, / ppm): 4.7 (t, 1H, CH), 5.0 (s, 1H, OH), 5.15 (s, 1H,= CH), 5.30 (s, 1H,= CH), 5.4 (s, 1H, CH), 6.80-7.3.20 (m, 9H, Ar -H), 9.95 (s, 1H, OH)13C NMR (DMSO-d6, / ppm): 33 (-CH), 75.0 ( =CH), 76.15 (=CH), 115.5- 148.0 (Ar-C and C=C), 157.40 (=C-OH). LCMS; m/z: 35; Analytical calculation for C1917N0: C, 74.75; H, 5.59; N, 4.59 % Found C, 74.33; H, 5.38; N, 4.45 %.Antibacterial and antifungal activities: All the newlysynthesized fused oxazoles were evaluated for their antibacterial activity against Gram-negative bacteria, Gram-positive bacteria, fungi and yeast using disc diffusion method. The zone of inhibition was measured in mm and the activity was compared with standard drug. The data is given in table-2.The sensitivity of micro-organisms to the tested compounds is identified in the following manner*; Highly active =Zone of Inhibition: 15-20 mm, Moderately active = Zone of inhibition: 10-15 mm, Slightly active = Zone of inhibition: 5-10 mm, No activity = Zone of inhibition: 0 mm, * Each result represents the average of triplicate readings.Result and DiscussionIn our present work we have carried out an efficient synthesis of fused oxazole using microwave in excellent yield. Clean reaction profile and good purity of the obtained product in some of the advantages associated with our protocol. The results are summarized in table-1 and table-2. The entire synthesized product were characterized by HNMR 13CNMR, IR, MS and elemental analysis and further, the compound were screened for anti-bacterial activities. Table-1 Characterization data of representative compounds 4 and 5 Compounds R Mol. Formula m.p. °°C %Yields Time (seconds) Color 4a H C 17 H 13 N0 2 S 95 80 120 Light Brown 4b 4-Cl C 17 H 12 N0 2 SCl 152 82 110 Brown 4c 4-OCH 3 C 18 H 15 N0 3 S 130-132 78 90 Dark Green 4d 4-OH C 17 H 12 N0 3 S 176 75 100 Light Brown 4e 3-OCH 3 , 4-OH C 18 H 15 N0 4 S 145-148 85 120 Brown 5a H C 19 H 15 N0 3 109-111 73 120 Light Green 5b 4-Cl C 19 H 14 N0 2 Cl 176-178 75 100 Light Brown 5c 4-OCH 3 C 20 H 17 N0 4 166 80 90 Dark Brown 5d 4-OH C 19 H 15 N0 3 126-127 70 80 Buff 5e 3-OCH 3 , 4-OH C 20 H 17 N0 4 196 77 110 Brown Table-2Antibacterialal activities of some representative compounds Compounds Zone of Inhibition (mm) Gram-negative Gram-positive Fungi Yeast E.coli P.Putide B.Subtilis S.lactis A.niger P.Sp. C.Albicans 4b 16 15 17 19 16 17 9 4c 17 16 19 20 18 10 10 4d 18 19 18 18 19 10 9 4e 19 18 17 19 20 9 9 5b 17 15 17 21 17 10 10 5c 16 17 17 21 19 10 9 5d 15 14 18 19 18 11 9 5e 19 18 20 20 19 10 9 DMSO 0 0 0 0 0 0 0 Ampicilin® 22 21 20 22 23 15 15 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(12), 42-47, December (2014) Res. J. Chem. Sci.International Science Congress Association 44 Conclusion In conclusion, we have developed a rapid and efficient method for the synthesis of fused oxazoles with excellent yields. The main advantage of this method is that reactions were found to clean and has operational simplicity. Since, column chromatography was not required to get the pure products, hence makes more attractive for chemist.Acknowledgement We are thankful to the Management of Guru Nanak College, G.T.B. Nagar, Mumbai for continuous support and respective facilities. We are also thankful to, The Director, TIFR Mumbai for providing spectral data. O O H R (1)COCO N O OH R N O S OH R S Br O Br O DMFDMFMicrowave(2)(3)(4)(5)Scheme-1 Figure-1 IR Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(12), 42-47, December (2014) Res. J. Chem. Sci.International Science Congress Association 45 Figure-2 H1 NMR Figure-3 C13 NMR Figure-4 Mass Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(12), 42-47, December (2014) Res. J. Chem. Sci.International Science Congress Association 46 Figure-5 IR Figure-6 PMR Figure-7 C13 NMR Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(12), 42-47, December (2014) Res. J. Chem. Sci.International Science Congress Association 47 Figure-8 MassReferences1.Griinanger, Paola Vita-Finzi, James E. 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