Trifluoromethylation

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Trifluoromethylation in organic chemistry describes any organic reaction that introduces a trifluoromethyl group in an organic compound.[1][2][3] Trifluoromethylated compounds are of some importance in pharma and agrochemicals. Several notable pharmaceutical compounds have a trifluoromethyl group incorporated: fluoxetine, mefloquine, Leflunomide, nulitamide, dutasteride, bicalutamide, aprepitant, celecoxib, fipronil, fluazinam, penthiopyrad, picoxystrobin, fluridone, norflurazon, sorafenib and triflurazin. A relevant agrochemical is trifluralin The development of synthetic methods for adding trifluoromethyl groups to chemical compounds is actively pursued in academic research.

History

The first to investigate trifluoromethyl groups in relationship to biological activity was F. Lehmann in 1927.[4] An early review appeared in 1958.[5] An early synthetic method was developed by Frédéric Swarts in 1892,[6] based on antimony fluoride. In this reaction benzotrichloride was reacted with SbF3 to form PhCF2Cl and PhCF3. In the 1930s Kinetic Chemicals and IG Farben replaced SbF3 with HF. The McLoughlin-Thrower reaction (1968) is an early coupling reaction using iodofluoroalkanes, iodoaromatic compounds and copper.[7] In 1969 Kobayashi & Kumadaki adapted their protocol for trifluoromethylations.[8][9]

McLoughlin-Thrower reaction (1968)

Reagents

Trifluoromethyltrimethylsilane

Trifluoromethyltrimethylsilane or Ruppert's reagent is a reagent for introducing a trifluoromethyl group introduced in 1984 by Ingo Ruppert[10][11] and was modified by Prakash and Olah for carbonyl compounds in 1989.[12] In the same year Stahly modified the reaction for phenols and anilines.[13] An example is the trifluoromethylation of cyclohexanone in THF using tetrabutylammonium fluoride.[14]

Trifluoromethylation using

Trifluoromethyltrimethylsilane[14]

The substrates can be aryl halides.[15][16] Potassium (trifluoromethyl)trimethoxyborate for this purpose has been synthesised from B(OMe)3, CF3SiMe3, and KF.[17] Aryl functionalization via C-H activation has also been reported[18][19]

Sodium trifluoroacetate

Sodium trifluoroacetate as a reagent for trifluoromethylations was introduced by Matsui in 1981. In the original scope the substrate was an aromatic halide and the metal salt copper(I)iodide.[20][21]

Trifluoromethane

Fluoroform (CF3H) has been employed as a trifluoromethylation reagent for aldehydes in combination with a strong base[22]

Trifluoromethylation fluoroform folleas 1998[22]

Trifluoroiodomethane

Trifluoroiodomethane is a reagent in aromatic coupling reactions. It has also been used with enones, for example with chalcone, a reaction catalysed by diethyl zinc and Wilkinson's catalyst:[23]

Trifluoromethylation using diethyl zinc and Wilkinson's catalyst[23]

Trifluoromethyl Sulfone

Trifluoromethyl Sulfone (PhSO2CF3) and Trifluoromethyl Sulfoxide (PhSOCF3) can be used for trifluoromethylations of electrophiles[24]

Trifluoromethanesulfonyl chloride

Trifluoromethanesulfonyl chloride (or Triflyl Chloride, CF3SO2Cl) can be used in a highly efficient method to introduce a trifluoromethyl group to aromatic and heteroaromatic systems, including known pharmaceuticals such as Lipitor. The chemistry is general and mild, and uses a photoredox catalyst and a light source at room temperature. [25] [26]

Sodium trifluoromethanesulfinate

Sodium trifluoromethanesulfinate (CF3SO2Na) as a trifluoromethylation reagent was introduced by Langlois in 1991.[27] The reaction requires t-butyl hydroperoxide and generally a metal and proceeds through a radical mechanism. The reagent has been applied with heterocyclic substrates[28]

Trifluorination Langlois reagent 2011[28]

Reaction types

Aromatic coupling reactions

In coupling reactions between aromatic compounds and metal-trifluoromethyl complexes the metal is usually copper, Pd and Ni are less prominent.[1] The reactions are stoichiometric or catalytic. In the McLoughlin-Thrower reaction (1962) iodobenzene reacts with trifluoroiodomethane (CF3I) and copper powder in dimethylformamide at 150°C to trifluoromethylbenzene. The intermediate in this reaction type is a perfluoromethyl-metal complex.

A palladium acetate catalysed reaction described in 1982 used zinc powder with the main intermediate believed to be CF3ZnI with Pd(0) is the active catalyst.[29][30] The first copper catalysed coupling was reported in 2009 and based on an iodoarene, a trifluoromethylsilane, copper iodide and 1,10-phenanthroline.[31] Variations include another CF3 donor potassium (trifluoromethyl)trimethoxyborate,[32] the use of aryl boronic acids[33][34] or the use of a trifluoromethyl sulfonium salt[35] or the use of a trifluoromethylcopper(I) phenanthroline complex.[36] A catalytic palladium catalysed reaction was reported in 2010 using aryl halides, (trifluoromethyl)triethylsilane and allylpalladium chloride dimer[37]

Aromatic trifluoromethylation Kitazume 1982[29] Aromatic catalytic

trifluoromethylation Oishi 2009[31]

Radical trifluoromethylation

In radical trifluoromethylation the active species is the trifluoromethyl free radical.[38] Reagents such as bromotrifluoromethane and haloform have been used for this purpose[39][40][41] but in response to the Montreal Protocol alternatives such as trifluoroiodomethane have been developed as replacement.[42][43] One particular combination is CF3I / triethylborane[44][45] Other reagents that generate the CF3 radical are sodium trifluoromethanesulfinate and bis(trifluoroacetyl) peroxide.

Trifluoromethylation using CF3I and triethylborane.

The base is 2,6-lutidine[44]

In the CF3 radical the fluorine atom is an electron-withdrawing group via the inductive effect but also a weak pi donor through interaction of the fluorine lone pair with the radical center's SOMO. Compared to the methyl radical the CF3 radical is pyramidal (angle 17.8°C) with a large inversion barrier, electrophilic and also more reactive. In reaction with styrene it is 440 times more reactive.[46] An early report (1949) describes the photochemical reaction of iodotrifluoromethane with ethylene to 3-iodo-1,1,1-trifluoropropane.[47] Reagents that have been reported for the direct trifluoromethylation of arenes are CF3I, CF3Br (thermal or photochemical), silver trifluoroacetate/TiO2 (photchemical) and sodium trifluoromethanesulfinate/Cu(OSO2CF3)2/tBuOOH.

Nucleophilic trifluoromethylation

In nucleophilic trifluoromethylation the active species is the CF3- anion.[48] In itself this anion is very unstable and collapses into a fluoride anion and difluorocarbene. The trifluoromethyl anion can be stabilized by removing electron density from the carbon atom for example by coordination to a metal like copper[49][50] or by creating a sigma bond to tin or silicon. Ruppert's reagent Me3SiCF3 is based on this last principle.[48] This reagent requires a fluoride initiator, usually a tetraalkylammonium fluoride such as TBAF. The CF3- anion can also be stabilised by trapping it by a strong electrophile that is used in excess. The reactivity of fluoroform in combination with a strong base such as t-BuOH with carbonyl compounds in DMF is an example.[48] Here CF3- and DMF form an hemiaminolate adduct ([Me2NCH(O)CF3]K).[51][52][53][54]

trifluoromethylation using methyl fluorosulfonyldifluoroacetate.

The intermediate is CF3Cu[49]

Electrophilic trifluoromethylation

In electrophilic trifluoromethylation the active trifluoromethyl donor group carries a positive charge.[55][56] The first relevant reagent, a diaryl(trifluoromethyl) sulfonium salt (Ar2S+CF3SbF6-) was developed in 1984 by reaction of an aryltrifluoromethyl sulfoxide 1 with SF3+SbF6− followed by reaction with an electron-rich arene.[57] The reagent was used in trifluoromethylation of a thiophenolate. S-(trifluoromethyl)dibenzothiophenium tetrafluoroborate is a commercially available and known trifluoromethylation reagent based on the same principle first documented in 1990.[58][59] In this type of compound sulfur has been replaced by oxygen, selenium and tellurium. Examples of substrates that have been investigated are pyridine, aniline, triphenylphosphine and the lithium salt of phenylacetylene.

Electrophilic Perfluoroalkylating Agents
5-(Trifluoromethyl)dibenzothiophenium
trifluoromethanesulfonate		 5-(Trifluoromethyl)dibenzothiophenium tetraborate 3,3-Dimethyl-1-(trifluoromethyl)-1,2-benziodoxole

Another group of trifluoromethyl donors are hypervalent iodine(III)–CF3 reagents for example 3,3-dimethyl-1-(trifluoromethyl)-1,2-benziodoxole.[60][61][62][63] Substrates are thiols, alcohols, phosphines, (hetero) arenes,[64] unactivated olefins[65] and unsaturated carboxylic acids.[66]

Trifluoromethylation at a thiol group using hypervalent iodine[64]

Asymmetric trifluoromethylation

In asymmetric trifluoromethylation the trifluoromethyl group is added to the substrate in an enantioselective way.[67] Ruppert's reagent has been used for this purpose in an asymmetric induction approach to functionalise chiral amino acid derivates,[68] carbohydrates,[69] and steroids. Because Ruppert's reagent requires a tetraalkylammonium fluoride, chiral ammonium fluorides have been employed in asymmetric catalysis.[70][71] In the field of electrophilic trifluoromethylation an early contribution involved reaction of a metal enolate with a trifluoromethyl chalcogen salt in presence of a chiral boron catalyst[72]

Asymmetic trifluorination Iseki 1994[70] Asymmetic trifluorination Caron 2003[71]

More recent examples of highly enantioselective methods for the α-trifluoromethylation of carbonyls are available through enamine catalysis of aldehydes (photoredox[73] or iodonium[74]), copper catalysis of β-ketoesters,[75] and radical addition to zirconium enolates.[76]

References

  1. ↑ 1.0 1.1 Aromatic Trifluoromethylation with Metal Complexes Olesya A. Tomashenko and Vladimir V. Grushin Chemical Reviews 2011 111 (8), 4475-4521 doi:10.1021/cr1004293
  2. ↑ Catalysis for fluorination and trifluoromethylation Takeru Furuya, Adam S. Kamlet & Tobias Ritter Nature 473, 470–477 (26 May 2011) doi:10.1038/nature10108
  3. ↑ Besset, T., Schneider, C. and Cahard, D. (2012), Tamed Arene and Heteroarene Trifluoromethylation. Angew. Chem. Int. Ed., 51: 5048–5050. doi:10.1002/anie.201201012
  4. ↑ Lehmann, F. Arch. Exptl. Path. Pharmakol. 1928, 130, 250.
  5. ↑ Yale, Harry L. (1959). "The Trifluoromethyl Group in Medicinal Chemistry". Journal of Medicinal and Pharmaceutical Chemistry 1 (2): 121–133. doi:10.1021/jm50003a001. 
  6. ↑ Swarts (1892). Acad. Roy. Belg 3 (24): 474. 
  7. ↑ A route to fluoroalkyl-substituted aromatic compounds involving fluoroalkylcopper intermediates V.C.R. Mcloughlin, J. Thrower Tetrahedron Volume 25, Issue 24, 1969, Pages 5921–5940 doi:10.1016/S0040-4020(01)83100-8
  8. ↑ Trifluoromethylation of aromatic compounds Yoshiro Kobayashi, Itsumaro Kumadaki Tetrahedron Letters Volume 10, Issue 47, 1969, Pages 4095–4096 doi:10.1016/S0040-4039(01)88624-X
  9. ↑ Fluoroform: an Efficient Precursor for the Trifluoromethylation of Aldehydes Pages 275-283 Benoı̂t Folléas, Ilan Marek, Jean-F. Normant, Laurent Saint-Jalmes Tetrahedron Volume 56, Issue 2, 7 January 2000, Pages 275–283 doi:10.1016/S0040-4020(99)00951-5
  10. ↑ Die ersten CF3-substituierten organyl(chlor)silane Ingo Ruppert, Klaus Schlich, Wolfgang Volbach Tetrahedron Letters Volume 25, Issue 21, 1984, Pages 2195–2198 doi:10.1016/S0040-4039(01)80208-2
  11. ↑ G. K. Surya Prakash; Andrei K. Yudin (1997). "Perfluoroalkylation with Organosilicon Reagents". Chem. Rev. 97 (3): 757–86. doi:10.1021/cr9408991. PMID 11848888. 
  12. ↑ Synthetic methods and reactions. 141. Fluoride-induced trifluoromethylation of carbonyl compounds with trifluoromethyltrimethylsilane (TMS-CF3). A trifluoromethide equivalent G. K. Surya Prakash, Ramesh Krishnamurti, and George A. Olah Journal of the American Chemical Society 1989 111 (1), 393-395 doi:10.1021/ja00183a073
  13. ↑ A new method for synthesis of trifluoromethyl-substituted phenols and anilines G. Patrick Stahly and Donald R. Bell The Journal of Organic Chemistry 1989 54 (12), 2873-2877 doi:10.1021/jo00273a020
  14. ↑ 14.0 14.1 1-TRIFLUOROMETHYL-1-CYCLOHEXANOL Submitted by: Pichika Ramaiah, Ramesh Krishnamurti, and G. K. Surya Prakash Checked by: Zhen-Yu Yang and Bruce E. Smart Org. Synth. 1995, 72, 232 pdf
  15. ↑ Morimoto, H., Tsubogo, T., Litvinas, N. D. and Hartwig, J. F. (2011), A Broadly Applicable Copper Reagent for Trifluoromethylations and Perfluoroalkylations of Aryl Iodides and Bromides. Angew. Chem., 123: 3877–3882. doi:10.1002/ange.201100633
  16. ↑ Aromatic trifluoromethylation catalytic in copper Masahiro Oishi , Hideaki Kondo and Hideki Amii Chem. Commun., 2009, 1909-1911 doi:10.1039/B823249K
  17. ↑ Knauber, T., Arikan, F., Röschenthaler, G.-V. and Gooßen, L. J. (2011), Copper-Catalyzed Trifluoromethylation of Aryl Iodides with Potassium (Trifluoromethyl)trimethoxyborate. Chem. Eur. J., 17: 2689–2697. doi:10.1002/chem.201002749
  18. ↑ Silver-Mediated Trifluoromethylation of Arenes Using TMSCF3 Yingda Ye, Shin Hee Lee, and Melanie S. Sanford Organic Letters 2011 13 (20), 5464-5467 doi:10.1021/ol202174a
  19. ↑ Hafner, A. and Bräse, S. (2012), Ortho-Trifluoromethylation of Functionalized Aromatic Triazenes. Angew. Chem. Int. Ed., 51: 3713–3715. doi:10.1002/anie.201107414
  20. ↑ A CONVENIENT TRIFLUOROMETHYLATION OF AROMATIC HALIDES WITH SODIUM TRIFLUOROACETATE Kiyohide Matsui, Etsuko Tobita, Midori Ando and Kiyosi Kondo Chemistry Letters Vol.10 , No.12(1981)pp.1719-1720 doi:10.1246/cl.1981.1719
  21. ↑ Nucleophilic trifluoromethylation of aryl halides with methyl trifluoroacetate Journal of Fluorine Chemistry, Volume 128, Issue 10, October 2007, Pages 1318-1325 Bernard R. Langlois, Nicolas Roques doi:10.1016/j.jfluchem.2007.08.001
  22. ↑ 22.0 22.1 Fluoroform: an efficient precursor for the trifluoromethylation of aldehydes Pages 2973-2976 Benoît Folléas, Ilan Marek, Jean-F Normant, Laurent Saint Jalmes Tetrahedron Letters Volume 39, Issue 19, 7 May 1998, Pages 2973–2976 doi:10.1016/S0040-4039(98)00391-8
  23. ↑ 23.0 23.1 TRIFLUOROMETHYLATION AT THE alpha-POSITION OF UNSATURATED KETONES: 4-PHENYL-3-(TRIFLUOROMETHYL)BUTAN-2-ONE Kazuyuki Sato, Masaaki Omote, Akira Ando, and Itsumaro Kumadaki Checked by: Scott E. Denmark and Won-jin Chung Org. Synth. 2006, 83, 177 Org. Synth. 2009, Coll. Vol. 11, 336 pdf
  24. ↑ Alkoxide- and Hydroxide-Induced Nucleophilic Trifluoromethylation Using Trifluoromethyl Sulfone or Sulfoxide G. K. Surya Prakash,*Jinbo Hu, and, and George A. Olah Organic Letters 2003 5 (18), 3253-3256 doi:10.1021/ol035045u
  25. ↑ http://f1000.com/13411094#recommendations
  26. ↑ Trifluoromethylation of Arenes and Heteroarenes by Means of Photoredox Catalysis" D. A. Nagib and D. W. C. MacMillan Nature (2011) 480, 224-228 doi:10.1038/nature10647
  27. ↑ Trifluoromethylation of aromatic compounds with sodiumtrifluoromethanesulfinate under oxidative conditions Bernard R. Langlois, Eliane Laurent, Nathalie Roidot Tetrahedron Letters Volume 32, Issue 51, 16 December 1991, Pages 7525–7528 doi:10.1016/0040-4039(91)80524-A
  28. ↑ 28.0 28.1 Innate C-H trifluoromethylation of heterocycles Yining Ji, Tobias Brueckl , Ryan D. Baxter, Yuta Fujiwara, Ian B. Seiple, Shun Su, Donna G. Blackmond, and Phil S. Baran doi:10.1073/pnas.1109059108 PNAS August 30, 2011 vol. 108 no. 35 14411-14415
  29. ↑ 29.0 29.1 PALLADIUM-CATALYZED CROSS-COUPLING REACTIONS BETWEEN ALLYL, VINYL OR ARYL HALIDE AND PERFLUOROALKYL IODIDE WITH ZINC AND ULTRASONIC IRRADIATION Tomoya Kitazume and Nobuo Ishikawa Chemistry Letters Vol.11 , No.1(1982)pp.137-140 doi:10.1246/cl.1982.137
  30. ↑ Ultrasound-promoted selective perfluoroalkylation on the desired position of organic molecules Tomoya Kitazume and Nobuo Ishikawa Journal of the American Chemical Society 1985 107 (18), 5186-5191 doi:10.1021/ja00304a026
  31. ↑ 31.0 31.1 Oishi, M., Kondo, H. & Amii, H. Aromatic trifluoromethylation catalytic in copper. Chem. Commun. 1909–1911 (2009).doi:10.1039/B823249K
  32. ↑ Knauber, T., Arikan, F., Roschenthaler, G.-V. & Gooßen, L. J. Copper-catalyzed trifluoromethylation of aryl iodides with potassium (trifluoromethyl) trimethoxyborate. Chem. Eur. J. 17, 2689–2697 (2011).doi:10.1002/chem.201002749
  33. ↑ Chu, L. & Qing, F.-L. Copper-mediated oxidative trifluoromethylation of boronic acids. Org. Lett. 12, 5060–5063 (2010). doi:10.1021/ol1023135
  34. ↑ Senecal, T. D., Parsons, A. T. & Buchwald, S. L. Room temperature aryl trifluoromethylation via copper-mediated oxidative cross-coupling. J. Org. Chem. 76, 1174–1176 (2011).doi:10.1021/jo1023377
  35. ↑ Cheng-Pan Zhang, Zong-Ling Wang, Prof. Dr. Qing-Yun Chen, Chun-Tao Zhang, Dr. Yu-Cheng Gu and Prof. Dr. Ji-Chang Xiao Copper-mediated trifluoromethylation of heteroaromatic compounds by trifluoromethyl sulfonium salts. Angew. Chem. Int. Edn 50, 1896–1900 (2011).doi:10.1002/anie.201006823
  36. ↑ Morimoto, H., Tsubogo, T., Litvinas, N. D. & Hartwig, J. F. A broadly applicable copper reagent for trifluoromethylations and perfluoroalkylations of aryl iodides and bromides. Angew. Chem. Int. Edn50, 3793–3798 (2011); doi:10.1002/anie.201100633
  37. ↑ Eun Jin Cho,Todd D. Senecal, Tom Kinzel, Yong Zhang, Donald A. Watson,and Stephen L. Buchwald The palladium-catalyzed trifluoromethylation of aryl chlorides Science 328, 1679–1681 (2010) doi:10.1126/science.1190524
  38. ↑ Strategies for nucleophilic, electrophilic, and radical trifluoromethylations Jun-An Ma, Dominique Cahard Journal of Fluorine Chemistry 128 (2007) 975–996 doi:10.1016/j.jfluchem.2007.04.026
  39. ↑ Unusual reactions resulting from the addition on olefins of trifluoromethyl radicals obtained from dissociative electron transfer between electrochemically generated aromatic anion radicals and trifluoromethyl bromide Tetrahedron Letters, Volume 30, Issue 37, 1989, Pages 4961-4964 Claude P. Andrieux, Laurence Gelis, Jean-Michel Saveant doi:10.1016/S0040-4039(01)80554-2
  40. ↑ Perfluoroalkyl-selenation of olefins Tetrahedron Letters, Volume 32, Issue 3, 14 January 1991, Pages 375-378 Kenji Uneyama, Kouichi Kitagawa, Kouichi Kitagawa doi:10.1016/S0040-4039(00)92632-7
  41. ↑ Generation of perfluoroalkyl radicals at low temperature by tellurolate mediated electron transfer Tetrahedron Letters, Volume 32, Issue 50, 9 December 1991, Pages 7425-7426 Kenji Uneyama, Masatomi Kanai doi:10.1016/0040-4039(91)80124-O
  42. ↑ Photocatalyzed reaction of trifluoromethyl iodide with steroidal dienones Gary H. Rasmusson, Ronald D. Brown, and Glen E. Arth The Journal of Organic Chemistry 1975 40 (6), 672-675 doi:10.1021/jo00894a002
  43. ↑ The photochemical rearrangement of a steroidal dienol triflate Tetrahedron Letters, Volume 28, Issue 52, 1987, Pages 6557-6560 Hsuan-Yin Lan-Hargest, John D. Elliott, Drake S. Eggleston, Brian W. Metcalf doi:10.1016/S0040-4039(00)96912-0
  44. ↑ 44.0 44.1 Triethylborane Induced Perfluoroalkylation of Silyl Enol Ethers and Ketene Silyl Acetals with Perfluoroalkyl Iodides Katsukiyo Miura,Yoshihiro Takeyama,Koichiro Oshima and Kiitiro Utimoto Bulletin of the Chemical Society of Japan Vol.64 , No.5(1991) pp.1542-1553 doi:10.1246/bcsj.64.1542
  45. ↑ Triethylborane induced perfluoroalkylation of silyl enol ethers or germyl enol ethers with perfluoroalkyl iodides Tetrahedron Letters, Volume 31, Issue 44, 1990, Pages 6391-6394 Katsukiyo Miura, Masahiko Taniguchi, Kyoko Nozaki, Koichiro Oshima, Kiitiro Utimoto doi:10.1016/S0040-4039(00)97073-4
  46. ↑ Studer, A. (2012), A "Renaissance" in Radical Trifluoromethylation. Angew. Chem. Int. Ed., 51: 8950–8958. doi:10.1002/anie.201202624
  47. ↑ 603. The reactions of fluorocarbon radicals. Part I. The reaction of iodotrifluoromethane with ethylene and tetrafluoroethyleneR. N. Haszeldine J. Chem. Soc., 1949, 2856-2861 doi:10.1039/JR9490002856
  48. ↑ 48.0 48.1 48.2 Nucleophilic trifluoromethylation Some recent reagents and their stereoselective aspects Bernard R. Langlois, Thierry Billard, Solveig Roussel Journal of Fluorine Chemistry 126 (2005) 173–179 doi:10.1016/j.jfluchem.2004.11.007
  49. ↑ 49.0 49.1 NEW, CONVENIENT ROUTE FOR TRIFLUOROMETHYLATION OF STEROIDAL MOLECULES Submitted by: Xiang-Shu Fei, Wei-Sheng Tian, Kai Ding, Yun Wang, and Qing-Yun Chen Checked by: Takayuki Yamakawa and Tohru Fukuyama Org. Synth. 2010, 87, 126 DOI
  50. ↑ Direct Cupration of Fluoroform Alessandro Zanardi, Maxim A. Novikov, Eddy Martin, Jordi Benet-Buchholz, and Vladimir V. Grushin Journal of the American Chemical Society 2011 133 (51), 20901-20913 doi:10.1021/ja2081026
  51. ↑ Electroorganic chemistry. 130. A novel trifluoromethylation of aldehydes and ketones promoted by an electrogenerated base Tatsuya Shono, Manabu Ishifune, Toshio Okada, and Shigenori Kashimura The Journal of Organic Chemistry 1991 56 (1), 2-4 doi:10.1021/jo00001a002
  52. ↑ Coupling of fluoroform with aldehydes using an electrogenerated base Rachid Barhdadi , Michel Troupel and Jacques Périchon Chem. Commun., 1998, 1251-1252 doi:10.1039/A801406J
  53. ↑ Fluoroform: an efficient precursor for the trifluoromethylation of aldehydes Tetrahedron Letters, Volume 39, Issue 19, 7 May 1998, Pages 2973-2976 Benoît Folléas, Ilan Marek, Jean-F Normant, Laurent Saint Jalmes doi:10.1016/S0040-4039(98)00391-8
  54. ↑ Nucleophilic Trifluoromethylation of Carbonyl Compounds and Disulfides with Trifluoromethane and Silicon-Containing Bases Sylvie Large, Nicolas Roques, Bernard R. Langlois The Journal of Organic Chemistry 2000 65 (26), 8848-8856 doi:10.1021/jo000150s
  55. ↑ Electrophilic Perfluoroalkylating Agents Teruo Umemoto Chemical Reviews 1996 96 (5), 1757-1778 doi:10.1021/cr941149u
  56. ↑ Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective Norio Shibata, Andrej Matsnev and Dominique Cahard Beilstein J. Org. Chem. 2010, 6, No. 65. doi:10.3762/bjoc.6.65
  57. ↑ Yagupolskii, L. M.; Kondratenko, N. V.; Timofeeva, G. N. J. Org. Chem. USSR 1984, 20, 103–106.
  58. ↑ Power-variable trifluoromethylating agents, (trifluoromethyl)dibenzothio- and -selenophenium salt system Umemoto Teruo, Ishihara Sumi Tetrahedron Letters Volume 31, Issue 25, 1990, Pages 3579–3582 doi:10.1016/S0040-4039(00)94447-2
  59. ↑ Power-variable electrophilic trifluoromethylating agents. S-, Se-, and Te-(trifluoromethyl)dibenzothio-, -seleno-, and -tellurophenium salt system Umemoto, T.; Ishihara, S. J. Am. Chem. Soc. 1993, 115, 2156–2164. doi:10.1021/ja00059a009
  60. ↑ Eisenberger, P., Gischig, S. and Togni, A. (2006), Novel 10-I-3 Hypervalent Iodine-Based Compounds for Electrophilic Trifluoromethylation. Chemistry - A European Journal, 12: 2579–2586. doi:10.1002/chem.200501052
  61. ↑ Kieltsch, I., Eisenberger, P. and Togni, A. (2007), Mild Electrophilic Trifluoromethylation of Carbon- and Sulfur-Centered Nucleophiles by a Hypervalent Iodine(III)–CF3 Reagent. Angewandte Chemie International Edition, 46: 754–757. doi:10.1002/anie.200603497
  62. ↑ Mild electrophilic trifluoromethylation of secondary and primary aryl- and alkylphosphines using hypervalent iodine(III)–CF3 reagents Patrick Eisenberger , Iris Kieltsch , Nicolas Armanino and Antonio Togni Chem. Commun., 2008, 1575-1577 doi:10.1039/B801424H
  63. ↑ Reactivity of a 10-I-3 Hypervalent Iodine Trifluoromethylation Reagent With Phenols Kyrill Stanek, Raffael Koller, and Antonio Togni The Journal of Organic Chemistry 2008 73 (19), 7678-7685 doi:10.1021/jo8014825
  64. ↑ 64.0 64.1 Organic Syntheses, Vol. 88, p.168 (2011). PREPARATION OF A TRIFLUOROMETHYL TRANSFER AGENT: 1-TRIFLUOROMETHYL-1,3-DIHYDRO-3,3-DIMETHYL-1,2-BENZIODOXOLE Submitted by Patrick Eisenberger, Iris Kieltsch, Raffael Koller, Kyrill Stanek, and Antonio Togni. Checked by Kay M. Brummond and Baptiste Manteau. PDF
  65. ↑ Parsons, A. T. and Buchwald, S. L. (2011), Copper-Catalyzed Trifluoromethylation of Unactivated Olefins. Angew. Chem. Int. Ed., 50: 9120–9123. doi:10.1002/anie.201104053
  66. ↑ He, Z., Luo, T., Hu, M., Cao, Y. and Hu, J. (2012), Copper-Catalyzed Di- and Trifluoromethylation of α,β-Unsaturated Carboxylic Acids: A Protocol for Vinylic Fluoroalkylations. Angew. Chem. Int. Ed., 51: 3944–3947. doi:10.1002/anie.201200140
  67. ↑ Asymmetric Fluorination, Trifluoromethylation, and Perfluoroalkylation Reactions Jun-An Ma and and Dominique Cahard Chemical Reviews 2004 104 (12), 6119-6146 doi:10.1021/cr030143e
  68. ↑ Inhibition of human leukocyte elastase (HLE) by N-substituted peptidyl trifluoromethyl ketones Jerry W. Skiles, Victor Fuchs, Clara Miao, Ronald Sorcek, Karl G. Grozinger, Scott C. Mauldin, Jana Vitous, Philip W. Mui, Stephen Jacober, and Journal of Medicinal Chemistry 1992 35 (4), 641-662 doi:10.1021/jm00082a005
  69. ↑ Synthesis of trifluoromethyl analogue of L-fucose and 6-deoxy-D-altrose Romesh C. Bansal, Barbara Dean, Sen-itiroh Hakomori and Tatsushi Toyokuni J. Chem. Soc., Chem. Commun., 1991, 796-798 doi:10.1039/C39910000796
  70. ↑ 70.0 70.1 Asymmetric trifluoromethylation of aldehydes and ketones with trifluoromethyltrimethylsilane catalyzed by chiral quaternary ammonium fluorides Tetrahedron Letters, Volume 35, Issue 19, 9 May 1994, Pages 3137-3138 Katsuhiko Iseki, Takabumi Nagai, Yoshiro Kobayashi doi:10.1016/S0040-4039(00)76850-X
  71. ↑ 71.0 71.1 Caron, Stéphane; Do, Nga M.; Arpin, Patrice; Larivée, Alexandre Enantioselective Addition of a Trifluoromethyl Anion to Aryl Ketones and Aldehydes Synthesis 2003(11): 1693-1698 doi:10.1055/s-2003-40889
  72. ↑ New Method for Trifluoromethylation of Enolate Anions and Applications to Regio-, Diastereo- and Enantioselective Trifluoromethylation Teruo Umemoto and Kenji Adachi The Journal of Organic Chemistry 1994 59 (19), 5692-5699 doi:10.1021/jo00098a030
  73. ↑ Nagib, David A.; Scott, Mark E.; MacMillan, David W. C. (2009). "Enantioselective α-Trifluoromethylation of Aldehydes via Photoredox Organocatalysis". Journal of the American Chemical Society 131 (31): 10875–10877. doi:10.1021/ja9053338. 
  74. ↑ Allen, Anna E.; MacMillan, David W. C. (2010). "The Productive Merger of Iodonium Salts and Organocatalysis: A Non-photolytic Approach to the Enantioselective α-Trifluoromethylation of Aldehydes". Journal of the American Chemical Society 132 (14): 4986–4987. doi:10.1021/ja100748y. 
  75. ↑ Deng, Qing-Hai; Wadepohl, Hubert; Gade, Lutz H. (2012). "Highly Enantioselective Copper-Catalyzed Electrophilic Trifluoromethylation of β-Ketoesters". Journal of the American Chemical Society 134 (26): 10769–10772. doi:10.1021/ja3039773. 
  76. ↑ Herrmann, Aaron T.; Smith, Lindsay L.; Zakarian, Armen (2012). "A Simple Method for Asymmetric Trifluoromethylation of-Acyl Oxazolidinones via Ru-Catalyzed Radical Addition to Zirconium Enolates". Journal of the American Chemical Society 134 (16): 6976–6979. doi:10.1021/ja302552e. 
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