GSC  Vol.1 No.3 , August 2011
Preparation of α-Bromoketones and Thiazoles from Ketones with NBS and Thioamides in Ionic Liquids
Ketones smoothly reacted with NBS in the presence of a catalytic amount of ptoluenesulfonic acid to give α-bromoketones in good yields in typical ionic liquids, such as [bmim]PF6 and [bmpy]Tf2N, and the ionic liquids could be repeatedly used for the same reaction after the extraction of the α-bromoketones. Then, the one-pot conversion of ketones into thiazoles by the treatment with NBS, and subsequently with thioamides could be also carried out in [bmim]PF6 and [bmpy]Tf2N, respectively Thus, [bmim]PF6 and [bmpy]Tf2N could be used as recyclable reaction media for the preparation α-bromoketones and thiazoles from ketones.

Cite this paper
nullY. Izumisawa and H. Togo, "Preparation of α-Bromoketones and Thiazoles from Ketones with NBS and Thioamides in Ionic Liquids," Green and Sustainable Chemistry, Vol. 1 No. 3, 2011, pp. 54-62. doi: 10.4236/gsc.2011.13010.
[1]   A. Benazzouz, T. Boraud, P. Dubedat, A. Boireau, J. M. Stutzmann and C. Gross, “Riluzole Prevents MPTP-Induced Parkinsonism in the Rhesus Monkey: A Pilot Study,” European Journal of Pharmacology, Vol. 284, No. 3, 1995, pp. 299-307. doi:10.1016/0014-2999(95)00362-O

[2]   [A. M. Liberatore, J. Schultz, C. Favre-Guilmard, J. Pommier, P. E. Chabrier and D. Bigg, “Butyl 2-(4-[1.1’- Biphenyl]-4-yl-1H-Imidazol-2-yl)ethylcarbamate, a Potent Sodium Channel Blocker for the Treatment of Neuropathic Pain,” Bioorganic & Medicinal Chemistry Letters, Vol. 17, No. 6, 2007, pp. 1746-1749. doi:10.1016/j.bmcl.2006.12.064

[3]   F. Haviv, J. D. Ratajczyk, R. W. DeNet, F. A. Kerdesky, R. L. Walters, S. P. Schmidt, J. H. Holms, P. R. Young and G. W. Carter, “3-[1-(2-Benzoxazolyl)hydrazino] Pro- panenitrile Derivatives: Inhibitors of Immune Complex Induced Inflammation,” Journal of Medicinal Chemistry, Vol. 31, No. 9, 1988, pp. 1719-1728. doi:10.1021/jm00117a010

[4]   F. Clemence, O. L. Marter, F. Delevalle, J. Benzoni, A. Jouanen, S. Jouquey, M. Mouren and R. Deraedt, “4-Hy- droxy-3-Quinolinecarboxamides with Antiarthritic and Analgesic Activities,” Journal of Medicinal Chemistry, Vol. 31, No. 7, 1988, pp. 1453-1462. doi:10.1021/jm00402a034

[5]   F. W. Bell, A. S. Cantrell, M. Hogberg, S. R. Jaskunas, N. G. Johansson, C. L. Jordon, M. D. Kinnick, P. Lind, J. M. Morin Jr, R. Noreen, B. Oberg, J. A. Palkowitz, C. A. Parrish, P. Pranc, C. Sahlberg, R. J. Ternansky, R. T. Va-sileff, L. Vrang, S. J. West, H. Zhang and X. X. Zhou, “Phenethylthiazolethiourea (PETT) Compounds, a New Class of HIV-1 Reverse Transcriptase Inhibitors. 1. Syn-thesis and Basic Structure-Activity Relationship Studies of PETT Analogs,” Journal of Medicinal Chemistry, Vol. 38, No.

[6]   K. Tsuji and H. Ishikawa, “Synthesis and An-ti-Pseudomonal Activity of New 2-Isocephems with a Dihydroxy- pyridone Moiety at C-7,” Bioorganic & Me-dicinal Che- mistry Letters, Vol. 4, No. 13, 1994, pp. 1661-1606. doi:10.1016/S0960-894X(01)80574-6

[7]   X. H. Gu, X. Z. Wan and B. Jiang, “Syntheses and Bio-logical Activities of Bis(3-Indolyl)thiazoles, Analogues of Marine Bis(Indole)alkaloid Nortopsentins,” Bioorganic & Medicinal Chemistry Letters, Vol. 9, No. 4, 1999, pp. 569-572. doi:10.1016/S0960-894X(99)00037-2

[8]   T. David, P. Enrico and X. Zhunjie, “One-Pot Synthesis of New 2,4,5-Trisubstituted 1,3-Thiazoles and 1,3-Sele- nazoles,” Tetrahedron, Vol. 65, No. 15, 2009, pp. 2982- 2988. doi:10.1016/j.tet.2009.01.104

[9]   X. Zhang, W. T. Teo, S. Chan and P. Chan, “Br?nsted Acid Catalyzed Cyclization of Propargylic Alcohols with Thioamides. Facile Synthesis of Di- and Tri-substituted Thiazoles,” The Journal of Organic Chemistry, Vol. 75, No. 18, 2010, pp. 6290-6293. doi:10.1021/jo101292r

[10]   K. M. Weiss, S. Wei and S. Tsogoera, “Novel One-Pot Process for the Synthesis of 1,3-Thiazoles via Organoca-talysed Epoxidation of Nitro-Olefins,” Organic & Bio-molecular Chemistry, Vol. 9, No. 9, 2011, pp. 3457-3461. doi:10.1039/c1ob05260h

[11]   E. K. Said, B. Sabine and M. Adberrahim, “Solid-Phase Synthesis of Imidazo[1,2-a]pyridines and Imidazo[1,2-a] pyrimidines,” Tetrahedron Letters, Vol. 44, No. 33, 2003, pp. 6265-6267. doi:10.1016/S0040-4039(03)01532-6

[12]   A. Mounir, M. Emmanuel, C. Oliver and C. T. Jean, “A Convenient Synthesis of Linear Pyridinoimidazo[1,2-a]- pyridine and Pyrroloimidazo[1,2-a]Pyridine cores,” Te-trahedron Letters, Vol. 48, No. 47, 2007, pp. 8392-8395. doi:10.1016/j.tetlet.2007.07.223

[13]   A. Hantzsch and J. H. Weber, “Ueber Verbindungen des Thiazols (Pyridins der Thiophenreihe),” Berichte der Deutschen Chemischen Gesellschaft, Vol. 20, No. 2, 1887, pp. 3118- 3132.

[14]   R. H. Wiley and L. C. Behr, “Organic Reactions,” Vol. 6, Wiley, New York, 1951, pp. 367-409.

[15]   G. K. S. Prakash, R. Ismail, J. Garcia, C. Panja, G. Rasul, T. Mathew and G. A. Olah, “α-Halogenation of Carbonyl Compounds: Halotrimethylsilane-Nitrate Salt Couple as an Efficient Halogenating Reagent System,” Tetrahedron Letters, Vol. 5, No. 11, 2011, pp. 1217-1221. doi:10.1016/j.tetlet.2011.01.039

[16]   R. M. Moriarty, R. K. Vaid and G. F. Koser, “[Hydroxy (organosulfonyloxy)iodo]arenes in Organic Synthesis,” Synlett, Vol. 7, 1990, pp. 365-383. doi:10.1055/s-1990-21097

[17]   G. F. Koser, Aldrichimica, 2001, 34, 89-102. papers:

[18]   T. Muraki, H. Togo and M. Yokoyama, “Reactivity and Synthetic Utility of 1-(Arenesulfonyloxy)benziodoxo- lones,” The Journal of Organic Chemistry, Vol. 64, No. 8, 1999, pp. 2883-2889. doi:10.1021/jo9825207

[19]   T. Nabana and H. Togo, “Reactivities of Novel [Hy-droxy(tosyloxy)iodo]arenes and [Hydroxy(phosphorylo- xy)iodo]arenes for α-Tosyloxylation and α-Phosphorylo- xylation of Ketones,” The Journal of Organic Chemistry, Vol. 67, No. 12, 2002, pp. 4362-4365. doi:10.1021/jo0200670

[20]   Y. Misu and H. Togo, “Novel Preparation of 2,1-Ben- zothiazine Derivatives from Sulfonamides with [Hy-droxy(tosyloxy)iodo]arenes,” Organic & Biomolecular Chemistry, Vol. 1, No. 8, 2003, pp. 1342-1346. doi:10.1039/b301330h

[21]   M. Ueno, T. Nabana and H. Togo, “Novel Oxidative α-Tosyloxylation of Alcohols with Iodosylbenzene and p-Toluenesulfonic Acid and Its Synthetic Use for Direct Preparation of Heteroaromatics,” The Journal of Organic Chemistry, Vol. 68, No. 16, 2003, pp. 6424-6426.

[22]   D. Kumar, N. M. Kumar, G. Patel, S. Gupta and R. S. Varma, “A Facile and Eco-friendly Synthesis of Diaryl-thiazoles and Diarylimidazoles in Water,” Tetrahedron Letters, Vol. 52, No. 16, 2011, pp. 1983-1986.

[23]   T. Welton, “Room-Temperature Ionic Liquids. Solvents for Synthesis and Catalysis,” Chemical Reviews, Vol. 99, No. 8, 1999, pp. 2071-2084. doi:10.1021/cr980032t

[24]   P. Wasserscheid and W. Keim, “Ionic Liquids—New ‘Solutions’ for Transition Metal Catalysis,” Angewandte Chemie International Edition, Vol. 39, No. 21, 2000, pp. 3772-3789. doi:10.1002/1521-3773(20001103)39:21<3772::AID-ANIE3772>3.0.CO;2-5

[25]   R. Sheldon, “Catalytic Reactions in Ionic Liquids,” Che- mical Communications, No. 23, 2001, pp. 2399-2407. doi:10.1039/b107270f

[26]   R. A. Sheldon, “Atom Efficiency and Catalysis in Organic Synthesis,” Pure Applied Chemistry, Vol. 72, No. 7, 2001, pp. 1233-1246. doi:10.1351/pac200072071233

[27]   M. J. Earle and K. R. Seddon, “Ionic Liquids. Green Sol-vents for the Future,” Pure Applied Chemistry, Vol. 72, No. 7, 2000, pp. 1391-1398. doi:10.1351/pac200072071391

[28]   H. Zhao, et al., “Poly(Isonicotinic Acid) Modified Glassy Carbon Electrode for Electrochemical Detection of Nore-pinephrine,” Analytica Chimica Acta, Vol. 454, No. 1, 2002, pp. 75-81. doi:10.1016/S0003-2670(01)01543-4

[29]   S. Lee, “Functionalized Imidazolium Salts for Task-Specific Ionic Liquids and Their Applications,” Chemical Communications, No. 10, 2006, pp. 1049-1063. doi:10.1039/b514140k

[30]   D. R. Macfarlane, J. M. Pringle, K. M. Johansson, S. A. Forsyth and M. Forsyth, “Lewis Base Ionic Liquids,” Chemical Communications, No. 18, 2006, pp. 1905-1917.

[31]   J. K. D. Surette, L. Green and R. D. Singer, “1-Ethyl-3- Methylimidazolium Halogenoaluminate Melts as Reaction Media for the Friedel-Crafts Acylation of Ferrocene,” Chemical Communications, No. 24, 2006, pp. 2753-2754. doi:10.1039/cc9960002753

[32]   C. J. Adams, M. J. Earle, G. Roberts, K. R. Seddon, Chem. Commun. 1998, 2097-2098.

[33]   Y. R. Jorapur, C. H. Lee, D. and Y. Chi, “Mono- and Dialkylations of Pyrrole at C2 and C5 Positions by Nuc-leophilic Substitution Reaction in Ionic Liquid,” Organic Letters, Vol. 7, No. 7, 2005, pp. 1231-1254. doi:10.1021/ol047446v

[34]   A. L. Monteiro, F. K. Zinn, R. F. De Souza and J. Dupont, “Asymmetric Hydrogenation of 2-Arylacrylic Acids Cat-alyzed by Immobilized Ru-BINAP Complex in 1-n- Butyl-3-Methy- limidazolium Tetrafluoroborate Molten Salt,” Tetrahedron: Asymmetry, Vol. 8, No. 2, 1997, pp. 177-179. doi:10.1016/S0957-4166(96)00485-5

[35]   P. J. Dyson, D. L. Ellis, D. G. Parker and T. Welton, “Arene Hydrogenation in a Room-Temperature Ionic Li- quid Using a Ruthenium Cluster Catalyst,” Chemical Communications, No. 1, 1999, pp. 25-26. doi:10.1039/a807447j

[36]   C. J. Adams, M. J. Earle and K. R. Seddon, “Stereoselec-tive Hydrogenation Reactions in Chloroaluminate(III) Io-nic Liquids: A New Method for the Reduction of Aromatic Compounds,” Chemical Communications, No. 11, 1999, pp. 1043-1044. doi:10.1039/a901302d

[37]   J. Howarth, K. Hanlon, D. Fayne and P. McCormac, “Moisture Stable Dialkylimidazolium Salts as Heteroge-neous and Homogeneous Lewis Acids in the Diels-Alder Reaction,” Tetrahedron Letters, Vol. 38, No. 17, 1997, pp. 3097-3100. doi:10.1016/S0040-4039(97)00554-6

[38]   J. G. Huddleston and R. D. Rogers, “Room Temperature Ionic Liquids as Novel Media for ‘Clean’ Liquid-Liquid Extraction,” Chemical Communications, No. 16, 1998, pp. 1765-1766. doi:10.1039/a803999b

[39]   C. W. Lee, “Diels-Alder Reactions in Chloroaluminate Ionic Liquids: Acceleration and Selectivity Enhancement,” Tetrahedron Letters, Vol. 40, No. 13, 1999, pp. 2461-2464. doi:10.1016/S0040-4039(99)00249-X

[40]   A. J. Carmichael, M. J. Earle, J. D. Holbrey, P. B. Mc- Cormac and K. R. Seddon, “The Heck Reaction in Ionic Liquids: A Multiphasic Catalyst System,” Organic Letters, Vol. 1, No. 7, 1999, pp. 997-1000. doi:10.1021/ol9907771

[41]   V. Calo, A. Nacci, L. Lopez and N. Mannarini, “Heck Reaction in Ionic Liquids Catalyzed by a Pd-Benzothiazole Carbene Complex,” Tetrahedron Letters, Vol. 41, No. 46, 2000, pp. 8973-8976. doi:10.1016/S0040-4039(00)01592-6

[42]   C. J. Mathews, P. J. Smith and T. Welton, “Palladium Catalysed Suzuki Cross-Coupling Reactions in Ambient Temperature Ionic Liquids,” Chemical Communications, No. 14, 2000, pp. 1249-1250. doi:10.1039/b002755n

[43]   T. Fukuyama, M. Shinmen, S. Nishitani, M. Sato and I. Ryu, “A Copper-Free Sonogashira Coupling Reaction in Ionic Liquids and Its Application to a Microflow System for Efficient Catalyst Recycling,” Organic Letters, Vol. 4, No. 10, 2002, pp. 1691-1694. doi:10.1021/ol0257732

[44]   K. G. Mayo, E. H. Nearhoof and J. J. Kiddle, “Micro-wave-Accelerated Ruthenium-Catalyzed Olefin Metathe-sis,” Organic Letters, Vol. 4, No. 9, 2002, pp. 1567-1570. doi:10.1021/ol025789s

[45]   V. Calo, A. Nacci, L. Lopez and V. L. Lerario, “Stereo-selective Synthesis of Electrophilic Spirocyclopropanes in Ionic Liquids,” Tetrahedron Letters, Vol. 41, No. 46, 2000, pp. 8977-8980. doi:10.1016/S0040-4039(00)01593-8

[46]   G. S. Owens and M. M. Abu-Omar, “Methyltrioxorhe-nium-Catalyzed Epoxidations in Ionic Liquids,” Chemical Communications, No. 13, 2000, pp. 1165-1166. doi:10.1039/b001661f

[47]   J. Howarth, “Oxidation of Aromatic Aldehydes in the Ionic Liquid [Bmim]PF6,” Tetrahedron Letters, Vol. 41, No. 34, 2000, pp. 6627-6629. doi:10.1016/S0040-4039(00)01037-6

[48]   I. A. Ansari and R. Gree, “TEMPO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones in Ionic Liquid [Bmim][PF6],” Organic Letters, Vol. 4, No. 9, 2002, pp. 1507-1509. doi:10.1021/ol025721c

[49]   R. Yanada and Y. Takemoto, “OsO4-Catalyzed Dihy-droxylation of Olefins in Ionic Liquid [Emim]BF4: A Recoverable and Reusable Osmium,” Tetrahedron Letters, Vol. 43, No. 38, 2002, pp. 6849-6852. doi:10.1016/S0040-4039(02)01461-2

[50]   Z. Liu, Z. C. Chen and Q. G. Zheng, “Mild Oxidation of Alcohols with O-Iodoxybenzoic Acid (IBX) in Ionic Liq-uid 1-Butyl-3-Methyl-Imidazolium Chloride and Water,” Organic Letters, Vol. 5, No. 18, 2003, pp. 3321-3324. doi:10.1021/ol0351549

[51]   J. S. Yadav, B. V. S. Reddy, A. K. Basak and A. V. Nar-saiah, “Recyclable 2nd Generation Ionic Liquids as Green Solvents for the Oxidation of Alcohols with Hypervalent Iodine Reagents,” Tetrahedron, Vol. 60, No. 9, 2004, pp. 2131-2135. doi:10.1016/j.tet.2003.12.056

[52]   B. S. Chhikara, S. Tehlan, A. Kumar, Synlett 2005, 63-66.

[53]   X. E. Wu, L. Ma, M. X. Ding and L. X. Gao, “Imidazo-lium Ionic Liquid-Grafted 2,2’-Bipyridine—A Novel Li-gand for the Recyclable Copper-catalyzed Selective Oxi-dation of Alcohols in Ionic Liquid [bmim][PF6],” Chemi-stry Letters, Vol. 34, No. 3, 2005, pp. 312-313. doi:10.1246/cl.2005.312

[54]   X. E. Wu, L. Ma, M. X. Ding and L. X. Gao, “TEM-PO-Derived Task-Specific Ionic Liquids for Oxidation of Alcohols,” ChemInform, Vol. 36, No. 32, 2005, pp. 607-610.

[55]   D. W. Morrison, D. C. Forbes and J. H. Davis Jr, “Base-Promoted Reactions in Ionic Liquid Solvents. The Knoevenagel and Robinson Annulation Reactions,” Te-trahedron Letters, Vol. 42, No. 35, 2001, pp. 6053-6056. doi:10.1016/S0040-4039(01)01228-X

[56]   Y. Y. Xie, Z. C. Chen and Q. G. Zheng, “Organic Reac-tions in Ionic Liquids: Ionic Liquid-Accelerated Cyclo-condensation of α-Tosyloxyketones with 2-Aminopyri- dine,” ChemInform, Vol. 33, No. 50, 2002, pp. 111- 114.

[57]   C. Su, Z. C. Chen and Q. G. Zheng, “Organic Reactions in Ionic Liquids: Knoevenagel Condensation Catalyzed by Ethylenediammonium Diacetate,” Synthesis, Vol. 0, No. 4, 2003, pp. 555-559.

[58]   S. Kitaoka, K. Nobuoka and Y. Ishikawa, “The First Uti-lization of Acidic Ionic Liquid for Preparation of Tetraa-rylporphyrins,” Chemical Communications, No. 17, 2004, pp. 1902-1903. doi:10.1039/b404241g

[59]   A. Sato, Y. Nakamura, T. Maki, K. Ishihara and A. Ya-mamoto, “Zr(IV), Fe(III), Ga(III), and Sn(IV) Binary Me- tal Complexes as Synergistic and Reusable Esterification Catalysts,” Advanced Synthesis & Catalysis, Vol. 347, No. 10, 2005, pp. 1337-1340. doi:10.1002/adsc.200505083

[60]   C. K. Z. Andrade, S. C. S. Takeda, L. M. Alves, J. P. Rodrigues, P. A. Z. Suarez, R. F. Brandao and V. C. D. Soares, “Molecular Sieves in Ionic Liquids as an Efficient and Recyclable Medium for the Synthesis of Imines,” Synlett, Vol. 12, 2004, pp. 2135-2138. doi:10.1055/s-2004-831328

[61]   R. X. Ren, L. D. Zueva and W. Ou, “Formation of ε-Caprolactam via Catalytic Beckmann Rearrangement Using P2O5 in Ionic Liquids,” Tetrahedron Letters, Vol. 42, No. 48, 2001, pp. 8441-8443. doi:10.1016/S0040-4039(01)01850-0

[62]   Y. Deng, F. Shi, J. Beng and K. Quio, “Ionic Liquid as a Green Catalytic Reaction Medium for Esterifications,” Journal of Molecular Catalysis A: Chemical, Vol. 165, No. 1-2, 2001, pp. 33-36. doi:10.1016/S1381-1169(00)00422-2

[63]   J. Fraga-Dubreuil, K. Bourahla, M. Rahmouni, J. P. Ba-zureau and J. Hamelin, “Catalysed Esterifications in Room Temperature Ionic Liquids with Acidic Counteranion as Recyclable Reaction Media,” Catalysis Communications, Vol. 3, No. 5, 2002, pp. 185-190. doi:10.1016/S1566-7367(02)00087-0

[64]   L. Brinchi, R. Germani, G. Savelli, “Ionic Liquids as Reaction Media for Esterification of Carboxylate Sodium Salts with Alkyl Halides,” Tetrahedron Letters, Vol. 44, No. 10, 2003, pp. 2027-2029. doi:10.1016/S0040-4039(03)00179-5

[65]   J. McNulty, S. Cheekoori, J. J. Nair, V. Larichev, A. Ca-pretta and A. J. Robertson, “A Mild Esterification Process in Phosphonium Salt Ionic Liquid,” Tetrahedron Letters, Vol. 46, No. 21, 2005, pp. 3641-3644. doi:10.1016/j.tetlet.2005.03.169

[66]   D. W. Kim, C. E. Song and D. Y. Chi, “New Method of Fluorination Using Potassium Fluoride in Ionic Liquid: Significantly Enhanced Reactivity of Fluoride and Im-proved Selectivity,” Journal of the American Chemical Society, Vol. 124, No. 35, 2002, pp. 10278-10279. doi:10.1021/ja026242b

[67]   C. Chiappe, D. Pieraccini and P. Saullo, “Nucleophilic Displacement Reactions in Ionic Liquids: Substrate and Solvent Effect in the Reaction of NaN3 and KCN with Alkyl Halides and Tosylates,” Journal of the American Chemical Society, Vol. 68, No. 17, 2003, pp. 6710-6715. doi:10.1021/jo026838h

[68]   L. Brinchi, R. Germani and G. Savelli, “Efficient Esteri-fication of Carboxylic Acids with Alkyl Halides Catalyzed by Fluoride Ions in Ionic Liquids,” Tetrahedron Letters, Vol. 44, No. 35, 2003, pp. 6583-6585. doi:10.1016/S0040-4039(03)01693-9

[69]   L. Brinchi, R. Germani and G. Savelli, “Ionic Liquids as Reaction Media for Esterification of Carboxylate Sodium Salts with Alkyl Halides,” Tetrahedron Letters, Vol. 44, No. 10, 2003, pp. 2027-2029. doi:10.1016/S0040-4039(03)00179-5

[70]   S. S. Mohile, M. K. Potdar and M. M. Salunkhe, “An Ionic Liquid-Mediated Expeditious Route to the Syntheses of Diaryl Sulfoxides,” Tetrahedron Letters, Vol. 44, No. 6, 2003, pp. 1255-1258. doi:10.1016/S0040-4039(02)02786-7

[71]   J. S. Yadav, B. V. S. Reddy, A. K. Basak and A. V. Nar-saiah, “[Bmim]PF6 and BF4 Ionic Liquids as Novel and Recyclable Reaction Media for Aromatic Amination,” Tetrahedron Letters, Vol. 44, No. 10, 2003, pp. 2217- 2220. doi:10.1016/S0040-4039(03)00037-6

[72]   S. R. S. S. Kotti, X. Xu, G. Li and A. D. Headly, “Effi-cient Nucleophilic Substitution Reactions of Highly Functionalized Allyl Halides in Ionic Liquid Media,” Te-trahedron Letters, Vol. 45, No. 7, 2004, pp. 1427-1431. doi:10.1016/j.tetlet.2003.12.051

[73]   S. T. Handy, “Grignard Reactions in Imidazolium Ionic Liquids,” The Journal of Organic Chemistry, Vol. 71, No. 12, 2006, pp. 4659-4662. doi:10.1021/jo060536o

[74]   M. C. Law, K. Wong and T. H. Chen, “Grignard Reagents in Ionic Liquids,” Chemical Communications, No. 23, 2006, pp. 2457-2459. doi:10.1039/b602718k

[75]   T. Yoshino, S. Imori and H. Togo, “Efficient Esterification of Carboxylic Acids and Phosphonic Acids with Trialkyl Orthoacetate in Ionic Liquid,” Tetrahedron, Vol. 62, No. 6, 2006, pp. 1309-1317. doi:10.1016/j.tet.2005.09.147

[76]   S. Imori and H. Togo, “Efficient Demethylation of N,N- Dimethylanilines with Phenyl Chloroformate in Ionic Liquids,” Synlett, No. 16, 2006, pp. 2629-2632.

[77]   Y. Tsuchiya, Y. Izumisawa and H. Togo, “3-exo-tet Cyc-lization of 2,2-Disubstituted 1,3-Dihalopropanes with In-dium in Aqueous and Ionic Liquid Solvent System,” Te-trahedron, Vol. 65, No. 36, 2009, pp. 7533-7537. doi:10.1016/j.tet.2009.06.123

[78]   H. M. Meshram, P. N. Reddy, P. Vishnu, K. Sadashiv and J. S. Yadav, “A Green Approach for Efficient α-Halo- genation of β-Dicarbonyl Compounds and Cyclic Ketones Using N-Halosuccinimides in Ionic Liquids,” Tetrahedron Letters, Vol. 47, No. 6, 2006, pp. 991-995. doi:10.1016/j.tetlet.2005.11.141

[79]   R. Rajagopal, D. V. Jarikote, R. J. Lahoti, T. Daniel and K. V. Srinivasan, “Ionic liquid Promoted Regioselective Monobromination of Aromatic Substrates with N-Bro- mosuccinimide,” Tetrahedron Letters, Vol. 44, No. 9, 2003, pp. 1815-1817. doi:10.1016/S0040-4039(03)00092-3

[80]   S. R. K. Pingali, M. Madhav and B. S. Jursic, “An Effi-cient Regioselective NBS Aromatic Bromination in the Presence of an Ionic Liquid,” Tetrahedron Letters, Vol. 51, No. 10, 2010, pp. 1383-1385. doi:10.1016/j.tetlet.2010.01.002

[81]   P. Ruggli and M Herzog, “über die Addition von Benzol an Symm. Dibrom-Diacetyl (Carbonylgruppen und Arom. Kohlenwasserstoffe, 1. Mitt.),” Helvetica Chimica Acta, Vol. 29, No. 1, 1946, pp. 95-101. doi:10.1002/hlca.19460290115

[82]   G. L. Song, “Novel Disubstituted Phenylene-Linked Bis- imidazole Derivatives: Facile Synthesis and Optical Pro- perties,” Helvetica Chimica Acta, Vol. 93, No. 12, 2010, pp. 2397-2405. doi:10.1002/hlca.201000014

[83]   S. Kumar, V. Gawandi, N. Capito and R. Philips, “Subs-tituent Effects on the Reaction of Beta-Benzoylalanines with Pseudomonas Fluorescens Kynureninase,” Bioche-mistry, Vol. 49, No. 36, 2010, pp. 7913-7919.

[84]   J. Wegmann and H. Dahn, “über die Synthese von Aryl-ketolen durch Addition von Aromatischen Kohlen-wasserstoffen in der Diacetylreihe (Carbonylgruppen und arom. Kohlenwasserstoffe, 2. Mitt.),” Helvetica Chimica Acta, Vol. 29, No. 1, 1949, pp. 101-103. doi:10.1002/hlca.19460290116

[85]   A. Arrieta, I. Ganboa and C. Palomo, “Reagents and Synthetic Methods 38. 4-(Dimethylamino)pyridinium Bromide Perbromide as a New Brominating Agent for Organic Compounds,” Synthetic Communications, Vol. 14, No. 10, 1984, pp. 939-945. doi:10.1080/00397918408063764

[86]   P. Hou, “Synthesis of 2-Phenylthiazoles from Alpha- Tosyloxyketones and Thiobenzamide in [Bmim][PF6] Io-nic Liquid at Ambient Temperature,” Journal of the Chi-nese Chemical Society, Vol. 53, Part 4, 2006, pp. 863- 866.

[87]   J. Hummerle, M. Spina, M. Schnuerch and M. Mihovi- lovic, Synthesis 2008, 19, 3099-3107.

[88]   M. Ueno and H. Togo, Synthesis 2004, 16, 2073-2077.

[89]   F. Asinger, “Einwirkung von Schwefel und Ammoniak auf Propiophenon, n-Butyrophenon und i-Butyrophenon,” Organic Chemistry and Biochemistry, Vol. 97, No. 5, 1966, pp. 1510-1522. doi:10.1007/BF00902605

[90]   J. Hummerle, M. Schnuerch and M. D. Mihovilovic, “A Guideline for the Arylation of Positions 4 and 5 of Thia-zole via Pd-Catalyzed Cross-Coupling Reactions,” Te-trahedron, Vol. 65, No. 5, 2010, pp. 8051-8059. doi:10.1016/j.tet.2010.07.081

[91]   Y. Ishiwata and H. Togo, “Title of This Paper,” Synlett, No. 17, 2008, pp. 2637-2641.

[92]   J. N. Kar, R. C. Acharya and M. K. Rout, “Quaternization of Thiazoles,” The Journal of Organic Chemistry, Vol. 38, No. 12, 1973, pp. 2164-2166. doi:10.1021/jo00952a011