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Table 2 continued 9 10 11 12 N hydrazine hydrate. Based on the data given in Table 2, the reaction appears to be compatible with both aryl and alkyl substitutions. All the reactions were clean, smooth, and provided the products 1{1–18} in good and high yields. The compounds were purified by column chromatography using 5–10% MeOH in CH2Cl2 as the eluent. All the final 2-amino- 1H-imidazoles 1{1–18} were characterized by 1 H and 13 C NMR spectroscopy. Their compositions were also confirmed by HRMS. 123 7 8 13 14 N N N N N N N N N N N N N N H N H N H N H N N H N Octyl N H Pentyl Hexyl PMB Br Br Cyclooctyl Br N H N H Bu PMB Br Br Br Br Br O O O O O O O O SO 2Me Br Cl Cl F SO 2Me NO 2 Mol Divers Cl Pentyl HN N 61 N H 1{9} Hexyl HN HN N N H N N H 1{7} SO 2Me 1{10} Cl PMB N Br HN N H 1{11} F SO 2Me 69 44 Cyclooctyl HN N 66 N H 1{12} Bu HN N 83 N H 1{13} NO 2 73 Octyl HN N 79 N H 1{8} PMB HN N 89 N H 1{14} In conclusion, we have developed a simple and practical microwave-assisted procedure for the preparation of substituted 2-amino-1H-imidazoles. We have investigated a onepot synthesis and cleavage of 2-hydroxy-2,3-dihydroimidazo [1,2-a]pyrimidinyl-4-ium bromides by hydrazine hydrate and found microwave irradiation to be very effective in this regard. A small library of 2-amino-1H-imidazoles was synthesized for screening for potential antiviral and antibacterial activities.
Mol Divers Table 2 continued All the reactions were carried out on a 4 mmol scale of 2-alkylaminopyrimidine 4 with 1.15 equiv of α-bromoketone 5 in MeCN (3 mL) a Isolated yield after column chromatography Experimental section Microwave irradiation experiments 15 16 17 N A monomode CEM-Discover microwave reactor (CEM Corporation, P.O. Box 200, Matthews, NC 28106) was used in the standard configuration as delivered, including proprietary software. All the experiments were carried out in sealed microwave process vials (10 mL) at the maximum power and temperature, as indicated in the tables. After completion of the reaction, the vial was cooled to 50 ◦ C via air-jet cooling before it was opened. General procedure for the one-pot two-step microwaveassisted synthesis of 2-amino-1H-imidazoles 1{1–18} In a microwave, vial (10 mL) was successively dissolved in dry MeCN (3 mL), the corresponding 2-aminopyrimidine (4 mmol) and α-bromoketone (4.6 mmol). The reaction tube was sealed and irradiated in a microwave reactor at a ceiling temperature of 80 ◦ C and a maximum power of 50 W for 30 min. After the reaction mixture was cooled with an air flow for 15 min, hydrazine hydrate (0.9 mL, 28 mmol of a 64% solution, 7 equiv.) was added, and the mixture was irradiated at a ceiling temperature of 90 ◦ C and a maximum power of 50 W for another 10 min. After the reaction mixture was cooled, hydrazine hydrate was removed by distillation with toluene (3 × 20 mL). The resulting residue was purified by column chromatography (silica gel; MeOH-DCM 1:9 v/v with 0.5% of 6 N ammonia in MeOH) to afford 1 as amorphous solid. 18 N N N N N H N N N N H N H N H Bu OMe Br Br Br Br O O O O SMe NO 2 OMe Bu HN HN OMe HN HN N N H N N H N N H N N H 1{15} 1{16} 1{17} 1{18} SMe NO 2 OMe Acknowledgments The support for this project was provided by the Research Fund of the <strong>University</strong> of Leuven and by the F.W.O. (Fund for Scientific Research—Flanders (Belgium)). E.D.S. is grateful to the <strong>University</strong> of Leuven for obtaining a postdoctoral fellowship, and S.B. to Erasmus Mundus External Cooperation Window Lot 15 India (EMECW15) for obtaining a scholarship. The authors thank Ir. B. Demarsin for HRMS measurements. References 1. Cafieri F, Fattorusso E, Mangoni A, Taglialatela Scafati O (1996) Dispacamides anti-histamine alkaloids from Caribbean agelas sponges. Tetrahedron Lett 3: 3587–3590. doi:10.1016/ 0040-4039(96)00629-6 2. Kobayashi J, Ohizumi Y, Nakamura H, Hirata Y (1986) A novel antagonist of serotonergic receptors, hymenidin, isolated from the Okinawan marine Sponge Hymeniacidon sp. Experientia 42: 1176–1177. doi:10.1007/BF01941300 3. Carmely S, Ilan M, Kashman Y (1989) 2-Amino imidazole alkaloids from the marine sponge leucetta chagosensis. Tetrahedron 45: 2193–2200. doi:10.1016/S0040-4020(01)80079-X 4. Bedoya Zurita M, Ahond A, Poupat C, Potier P (1989) Première synthèse totale de la girolline. Tetrahedron 45: 6713–6720. doi:10. 1016/S0040-4020(01)89141-9 5. Gross H, Kehraus S, Koenig GM, Woerheide G, Wright AD (2002) New and biologically active imidazole alkaloids from two sponges of the genus leucetta. J Nat Prod 65: 1190–1193. doi:10. 1021/np020050c 6. HassanW,EdradaR,EbelR,WrayV,BergA,VanSoestR, Wiryowidagdo S, Proksch P (2004) New imidazole alkaloids from the indonesian sponge leucetta chagosensis. J Nat Prod 67: 817–822. doi:10.1021/np0305223 7. Copp BR, Fairchild CR, Cornell L, Casazza AM, Robinson S, Ireland CM (1998) Naamidine A is an antagonist of the epidermal growth factor receptor and an in vivo active antitumor agent. J Med Chem 41: 3909–3911. doi:10.1021/jm980294n 88 53 61 60 123
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Saurashtra University Re - Accredit
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JANUARY-2011 Statement under O. Ph.
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Acknowledgment This thesis arose in
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since I was a child. My Mother Hans
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CHAPTER - 2 Microwave Assisted Synt
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5.5 Results and discussion 156 5.6
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Ms Mesyl MW Microwave NBS N-bromosu
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1. Microwave Assisted Organic Synth
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1.4 Heating Mechanism In microwave
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1.5. Effects of solvents Every solv
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1.7 Application of microwave in org
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aromatic amines, Lancini’s group
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1.9 2-Aminoimidazole Alkaloids The
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Recently group of Erik 83 described
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1.10 Methods for the preparation of
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R 1 O X R 2 NH 2 H 2N NAc R 1 HN R
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this manifold, was reported in 1925
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Another route to 4(5)-acyl-2-amino-
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this series of compounds against th
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documented. Extra care is needed be
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Very recently the research group of
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OH a,b O N H2N N Boc N 3 H N R N N
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1.12.2 Biofilm Growth Cycle 1) Plan
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can survive both the onslaught of a
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[26] Leadbeater, N. E. (2004) Chemi
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[86] Kreutzberger, A. (1962) J. Org
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Microwave Assisted Synthesis & Stru
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2.1 Introduction As described in ch
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2.3 Proposed Mechanism: Regarding t
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No. 12 60 120 traces 84 a All react
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the development of biofilm related
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In first instance, a series of 2-hy
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Br N N N R 1 OH Br N N N R 1 OH Fig
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do have a very strong effect agains
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2.6 Conclusion In the present study
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2.8 Biological assays 2.8.1 Static
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2.9 Experimental protocol: 2.9.1 Ge
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temperature of 80 °C and a maximum
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29.5,29.4, 29.2, 27.0, 22.6, 14.1.
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Yield: 78 %. 1 H NMR (300 MHz, CDCl
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N Br N N C 14H 29 OH Yield: 72 %. 1
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(75.5 MHz, CDCl3): δ = 167.7, 154.
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N Br N N C 14H 29 OH Cl Yield: 90 %
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2-(3,4-Dichlorophenyl)-2-hydroxy-1-
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N Br N N C 8H 17 OH NO 2 Yield: 49
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C3H7 HN N N H Cl Cl Yield : 70 %. 1
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(s, 1H), 3.16 (s, 3H), 1.80 (m, 2H)
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5-(4’-Nitrobiphenyl-4-yl)-N-octyl
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2.11 Representative NMR spectra 2.1
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2.11.3 10.4329 0.7429 151.5720 10.0
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[21] Matz C, McDougald D, Moreno A.
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Chapter-3 Structure Activity Relati
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imidazoles, where the addition of a
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3.4 Result and Discussion It was fo
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No. H 2N Compound Code N N C8H17 R1
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medium used in the set-up to monito
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H 2N N N N H2N N R R Figure-1 Effec
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3.5.3 Cyclo-alkyl 2-aminoimidazoles
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3.6. Conclusion In the present stud
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3.8. Experimental protocols 3.8.1 G
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122.6, 54.6, 33.3(×2), 27.3 (×2),
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Yield: 52 %. 1 H NMR (300 MHz, CDCl
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5-(4-Chlorophenyl)-1-cyclooctyl-1H-
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Yield: 50 %. Mp: 76-78 ° C. 1 H NM
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5-(4-Chlorophenyl)-1-cyclobutyl-1H-
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Yield: 66%. 1 H NMR (300 MHz, CDCl3
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3.10 Representative NMR spectra 3.1
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3.11 References [1] (a) Alvi K. A,
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Copper Catalyzed Microwave Assisted
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4.1 Introduction There are only a f
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(Table-1, No- 6). Next reaction tem
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No. Product, Yield b (%) No. Produc
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4.4 Possible Mechanism Regarding th
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4.7 Experimental protocols 4.7.1 Ge
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Page 181 and 182: SUMMARY The work represented in the
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