Electrophilic trifluoromethylthiolation of carbonyl compounds

Article abstract of DOI:10.1002/chem.201403409

A general method for the α-trifluoromethylthiolation of carbonyl compounds, without prefunctionalization, has been developed. Aldehydes, ketones, esters, amides, keto-esters, alkaloids, and steroids have been trifluoromethylthiolated with good yields. This work, proposing a new reagent for electrophilic trifluoromethylthiolation, provides a route towards the original synthesis of various trifluoromethylthiolated molecules for further applications.

Full text of DOI:10.1002/chem.201403409

DOI: 10.1002/chem.201403409
Communication
&
Synthetic Methods
Electrophilic Trifluoromethylthiolation of Carbonyl Compounds
Sꢀbastien Alazet,[a, b] Luc Zimmer,[b, c] and Thierry Billard*[a, b]
Carbonyl compounds constitute a large family of interesting
building blocks for various syntheses.[7] Furthermore, a wide
Abstract: A general method for the a-trifluoromethylthio-
range of bioactive and natural compounds possess a carbonyl
function.[8] Consequently, a-trifluoromethylthiolated carbonyl
molecules could be of great interest for further applications.
To date, few a-trifluoromethylthiolation reactions of carbonyl
compounds have been described in the literature. If such com-
pounds can react with CF3SCl,[9] the high toxicity[10] of this gas-
eous reagent precludes its utilization. Keto-esters (and b-dike-
tones) are the most studied compounds. These compounds
can be trifluoromethylthiolated with electrophilic reagents
(Figure 1; 2–4). Some asymmetric reactions have also been de-
veloped with tertiary keto-esters.[11]
lation of carbonyl compounds, without prefunctionaliza-
tion, has been developed. Aldehydes, ketones, esters,
amides, keto-esters, alkaloids, and steroids have been tri-
fluoromethylthiolated with good yields. This work, propos-
ing a new reagent for electrophilic trifluoromethylthiola-
tion, provides a route towards the original synthesis of
various trifluoromethylthiolated molecules for further ap-
plications.
Fluorinated molecules are often studied for a wide range of
applications, particularly in life science.[1] However, a major
problem concerns transmembrane permeation, which is crucial
for the biodisponibility of therapeutic molecules and, conse-
quently, for the administrated dose of the drug candidate.[2]
The trifluoromethylthio group (CF3S) is one of the most lipo-
philic substituents known[3] and, consequently, its presence in
organic molecules can provide crucial physicochemical modifi-
cations.[4] Because of the growing interest in such substituents,
reliable methods for their introduction into organic molecules
are increasingly required.
Figure 1. Reagents for electrophilic trifluoromethylthiolation.
Numerous methods to introduce this group into organic
substrates have been described in the literature.[5] However,
these methods are, in general, indirect methods or require spe-
cific skills to manipulate aggressive reagents. From a retrosyn-
thetic point of view, the direct disconnection of the CF3S
group from the target molecule constitutes a more classical
strategy for synthetic chemists non-specialized in fluorine
chemistry. Recently, some elegant methods have emerged to
propose such reactions.[5a,6]
Enantioselective trifluoromethylthiolations of oxindoles have
also been performed by using 4 or CF3SAg.[12] With the excep-
tion of the trifluoromethylthiolation of an aldehyde,[11c] no reac-
tions of other simple carbonyl compounds have been de-
scribed with electrophilic reagents. On the contrary, several
esters and ketones have been trifluoromethylthiolated with nu-
cleophilic reagents, starting from diazo compounds with
CF3SAg or CF3SCu,[13] or from a-bromo ketones with (S)-tri-
fluorothiocarbonate.[14]
These methods are interesting, but they suffer some draw-
backs. For the nucleophilic method, the necessary use of the
relatively unstable CF3SÀ anion confers some limitations to
such a strategy. The method developed by Zard,[14] uses an (S)-
trifluorothiocarbonate to generate this anion in situ. This
method is an interesting alternative, but requires the prelimi-
nary preparation of a-bromo ketones. Electrophilic trifluorome-
thylthiolations, using reagents 2–4, have been applied to
a more restricted family of compounds. Furthermore, the re-
agents, 2, developed by Shen and co-workers,[11c] and 4, re-
cently reintroduced by Rueping, Shen, and co-workers,[11a,15]
are prepared by using the CF3SÀ anion, which requires some
precautions and relevant expertise because of its instability. Re-
agent 3, developed by Shibata,[11f] has circumvented this draw-
[a] S. Alazet, Dr. T. Billard
Institute of Chemistry and Biochemistry (ICBMS - UMR CNRS 5246)
Universitꢀ de Lyon, Universitꢀ Lyon 1, CNRS
43 Bd du 11 novembre 1918–69622 Lyon (France)
E-mail: Thierry.billard@univ-lyon1.fr
[b] S. Alazet, Prof. L. Zimmer, Dr. T. Billard
CERMEP - in vivo imaging
Groupement Hospitalier Est
59 Bd Pinel - 69003 Lyon (France)
[c] Prof. L. Zimmer
Lyon Neuroscience Research Center
(UMR CNRS 5292, UMR INSERM 1028)
Groupement Hospitalier Est
59 Bd Pinel - 69003 Lyon (France)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201403409.
Chem. Eur. J. 2014, 20, 1 – 6
1
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
&
These are not the final page numbers! ÞÞ

Communication
back, but the scope of reactivity is relatively restrained to only
a few keto-esters.
In this context, trifluoromethanesulfenamide 1a can be
easily prepared, starting from commercially available reagents,
which can be used without any specific experimental exper-
tise.[16] This substrate has proved to be an efficient electrophilic
trifluoromethylthiolating reagent.[17]
Consequently, to extend the reactivity of 1a, and to expand
the availability of a-trifluoromethylthiolated carbonyl com-
pounds, reactions between 1a and enolizable carbonyl com-
pounds have been envisaged. Unfortunately, no attempts have
succeeded to form the expected a-trifluoromethylthiolated
acetophenone starting from 1a. Hypothesizing that 1a is not
electrophilic enough to react with enolates, a more reactive
derivative has been targeted. Therefore, an amine bearing
a stronger electron-withdrawing group has been used to syn-
thesize new reagent 1b.[16] This compound can be prepared
on a 20 g scale with an overall yield of 80%. This new reagent
has been used for the a-trifluoromethylthiolation of the eno-
late of acetophenone (5a) (Table 1).
Table 1. Reaction of 1b with enolate of 5a.
Entry
Base [(equiv)]
T [8C]
1b [(equiv)]
6a [%][a]
1
2
3
4
5
6
tBuOLi (1.1)
tBuONa (1.1)
LiHMDS (1.1)
LDA (1.1)
LDA (1.2)
tBuOLi (1.2)
0
0
À78
À78
À78
0
1.2
1.2
1.2
1.2
2.2
2.4
60
55
50
60
88
64
Figure 2. a-trifluoromethylthiolation of various carbonyl compounds.
[a] 2.4 equiv of LDA, 08C. [b] 24 h at 08C. Yields shown are of isolated prod-
ucts; values in parentheses are yields as determined by 19F NMR spectrosco-
py using PhOCF3 as an internal standard.
[a] Yield of products, as determined by 19F NMR spectroscopy using
PhOCF3 as an internal standard. LiHMDS=lithium hexamethyl disilazide.
starting from acetophenone (5a). These results confirm that
the CF3S group is a strong electron-withdrawing group.
These conditions for a-trifluoromethylthiolation (Table 1, en-
tries 4 or 5) have also been extended to carbonyl compounds
(Figure 2).
Regardless of the base used, only the product of bistrifluoro-
methylthiolation, 6a, is observed. By using 2.2 equivalents of
1b, compound 6a is formed in good yield (entries 5 and 6).
Such results suggest that the monoadduct, 7a, could also be
deprotonated to react with 1b. However, if diisopropylamine,
generated from lithium diisopropylamide (LDA), can, eventual-
ly, deprotonate 7a, in the case of tBuOLi or tBuONa, no base is
generated apart from the lithium sulfonamide 8-Li, arising
from the reaction of 1b. Such species are known to be very
weak bases, therefore, the potential role of 8-Li in this reaction
must be elucidated.[18]
In general, the reaction gives good results, for example, for
the acetophenone, only bis-addition is observed with primary
compounds (6a–d). These bistrifluoromethylthiolated products
were obtained with good yields when using 2.2 equivalents of
1b. With secondary compounds, the monotrifluoromethylthio-
lated products, 7, are generally the major, or often, the only
compounds formed. This result can be rationalized by the
Consequently, monoadduct 7a has been prepared by decar-
boxylation of 8n (see Figure 2) and then engaged in a a-tri-
fluoromethylthiolation reaction by using only 8-Li as a base
(Scheme 1). The formation of 6a was observed with good
yield, confirming the ability of 8-Li to deprotonate 7a. It
should be noted that these conditions did not work when
Scheme 1. a-trifluoromethylthiolation of 7a with 8-Li as a base. Ts=tosyl.
&
&
Chem. Eur. J. 2014, 20, 1 – 6
www.chemeurj.org
2
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

Communication
steric hindrance of 7 preventing the approach of the hindered
base (8-Li or diisopropylamine) for the second deprotonation.
In the case of tetralone, the bis-adduct, 6g, can be obtained
after a longer reaction time, at room temperature, whereas no
bis-addition is observed with cyclohexanone (7h). This reaction
also provides good results with amides (6c and 7k), esters (6d
and 7j), and a free carboxylic acid (7l). With an Oppolzer’s re-
agent, the mono a-trifluoromethylthiolated product (7m) is
obtained with good yields and with a diastereoisomeric ratio
of 85:15. As previously described in the literature with other
reagents,[11] keto-esters can also be a-trifluoromethylthiolated
(7n–o). For 7o, the moderate yield observed could be rational-
ized by the steric hindrance of the tertiary starting material.
Schiff bases of glycine have also been a-trifluoromethylthiolat-
ed with good yields (7p–q). It should be noted that the ob-
tained compounds are occasionally difficult to purify because
of their volatilities, and especially because some of the ob-
tained compounds are in equilibrium with their enol forms
(due to the high acidity of the a hydrogen atom), which are
difficult to elute from silica. This can explain the variations ob-
served between the crude and isolated yields.
Scheme 2. Base-catalyzed a-trifluoromethylthiolation. [a] 24 h. [b] 5 min.
Yields shown are those of isolated products; values in parentheses are yields
as determined by 19F NMR spectroscopy using PhOCF3 as an internal stan-
dard. EWG=electron-withdrawing group.
tained than with the stoichiometric conditions. In the case of
Schiff bases (7p–q) the reaction is very rapid and only 5 min
was required for the completion of the reaction.
This methodology has been applied, as follows, to more
elaborate compounds, possessing some biological activities
(Figure 3).
To extend such strategies to the synthesis of various valu-
able building blocks, a-bromo carbonyl compounds have also
been engaged in the trifluoromethylthiolation reaction
(Scheme 3).
Scheme 3. a-trifluoromethylthiolation of a-bromo compounds. Yields shown
were determined by 19F NMR spectroscopy using PhOCF3 as an internal stan-
dard.
Figure 3. a-trifluoromethylthiolation of bioactive molecules. Yields shown
are of isolated products; values in parentheses are yields as determined by
19F NMR spectroscopy using PhOCF3 as an internal standard.
Depending on the starting compounds (ketone 9a or ester
9d), different products are formed. With bromoacetophenone
9a, expected product 10a is obtained with a small amount of
bistrifluoromethylthiolated compound 6a. On the contrary,
with ester 9d, only the unexpected bistrifluoromethylthiolated
compound 6d is formed. The only conceivable explanation is
to envisage the debromination of 10 by 8-Li, generated during
the formation of 10, to form an enolate that is able to react
with 1b to give 6. The debromination of 10 can only be per-
formed with the non-enol form, which predominates in ester
10d, whereas ketone 10a is mainly in the enol form under the
reaction conditions and, consequently, is “protected” against
the side debromination. This debromination step has been
proven by the successful formation of product 6a by mixing
10a and 1b in the presence of 8-Li.
Good yields were obtained, despite the presence of other
functionalities in the molecules. To our knowledge, the exam-
ple of the santonin, 7s, constitutes the first a-trifluorome-
thylthiolation of a lactone. For santonin and cholestenone,
good diastereomeric ratios have also been observed. The con-
figuration of each major diastereomer (drawn in Figure 3)
could be determined by NOESY and HOESY (HÀF) experiments.
Because the ability of sulfonamide 8-Li to deprotonate
strong acidic hydrogen atoms has been previously underlined,
base-catalyzed conditions with strong acidic starting materials,
such as keto-esters or Schiff base of glycine have been tested
(Scheme 2).
Good yields were obtained under these conditions. Surpris-
ingly, in the case of the keto-esters (5o) better results are ob-
Chem. Eur. J. 2014, 20, 1 – 6
www.chemeurj.org
3
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
&
These are not the final page numbers! ÞÞ

Communication
Finally, since silyl enol ethers are well-known stabilized forms
of enolate, their reactivity with 1b has also been examined
(Scheme 4).
the French Ministry of Research are thanked for their financial
supports. The French Fluorine Network is also thanked for its
support.
Keywords: carbonyl compounds
·
enols
·
fluorine
·
trifluoromethanesulfenamide · trifluoromethylthiolation
[1] a) M. Hird, Chem. Soc. Rev. 2007, 36, 2070–2095; b) T. Hiyama, Organo-
fluorine Compounds: Chemistry and Applications, Springer, Berlin, 2000;
c) P. Kirsch, Modern Fluoroorganic Chemistry: Synthesis Reactivity, Applica-
tions, Wiley-VCH, Weinheim, 2013; d) B. E. Smart, J. Fluorine Chem.
2001, 109, 3–11; e) A. Becker, Inventory of Industrial Fluoro-biochemicals,
Eyrolles, Paris, 1996; f) S. C. Cherkofsky (du Pont de Nemours, E. I., and
Co., USA), US4267184 A, 1981 [Chem. Abstr. 95:61982]; g) W. K. Hag-
mann, J. Med. Chem. 2008, 51, 4359–4369; h) P. Jeschke, ChemBioChem
2004, 5, 570–589; i) B. R. Langlois, T. Billard, S. Large, N. Roques, in Fluo-
rinated Bioactive Compounds in the Agricultural & Medical Fields, Chemi-
cal & Polymer, 1999, pp. 24, 21–24, 28; j) K. Muller, C. Faeh, F. Diederich,
Science 2007, 317, 1881–1886; k) S. Purser, P. R. Moore, S. Swallow, V.
Gouverneur, Chem. Soc. Rev. 2008, 37, 320–330; l) J. Szmuszkovicz, E. M.
Glenn, R. V. Heinzelman, J. B. Hester, Jr., G. A. Youngdale, J. Med. Chem.
1966, 9, 527–536.
[2] a) D. E. Clark, Drug Discovery Today 2003, 8, 927–933; b) J. Kelder,
P. D. J. Grootenhuis, D. M. Bayada, L. P. C. Delbressine, J.-P. Ploemen,
Pharm. Res. 1999, 16, 1514–1519; c) U. Norinder, M. Haeberlein, Adv.
Drug Delivery Rev. 2002, 54, 291–313; d) A. Avdeef, Absorption and Drug
Development: Solubility, Permeability, and Charge State, Wiley, Hoboken,
2012; e) D. A. Smith, C. Allerton, H. Kubinyi, H. Walker, D. K. Walker, R.
Mannhold, G. Folkers, Pharmacokinetics and Metabolism in Drug Design,
Wiley-VCH, Weinheim, 2012.
[3] C. Hansch, A. Leo, R. W. Taft, Chem. Rev. 1991, 91, 165–195.
[4] a) Fluorine in Medicinal Chemistry and Chemical Biology (Ed.: I. Ojima),
Wiley, Chichester, 2009; b) J.-P. Begue, D. Bonnet-Delpon, Bioorganic
and Medicinal Chemistry of Fluorine, John Wiley & Sons, Hoboken, 2008.
[5] a) F. Toulgoat, S. Alazet, T. Billard, Eur. J. Org. Chem. 2014, 2415–2428;
b) V. N. Boiko, Beilstein J. Org. Chem. 2010, 6, 880–921; c) F. Leroux, P.
Jeschke, M. Schlosser, Chem. Rev. 2005, 105, 827–856.
[6] a) A. Tlili, T. Billard, Angew. Chem. 2013, 125, 6952–6954; Angew. Chem.
Int. Ed. 2013, 52, 6818–6819; b) G. Landelle, A. Panossian, S. Pazenok,
J.-P. Vors, F. R. Leroux, Beilstein J. Org. Chem. 2013, 9, 2476–2536.
[7] a) J. Alvarez-Builla, J. J. Vaquero, J. Barluenga, Modern Heterocyclic
Chemistry, Wiley-VCH, Weinheim, 2011; b) F. A. Carey, R. J. Sundberg, Ad-
vanced Organic Chemistry, Springer, New York, 2000, pp. 449–508.
[8] a) E. Fattorusso, W. H. Gerwick, O. Taglialatela-Scafati, Handbook of
Marine Natural Products., Springer-Verlag GmbH, Berlin, 2012; b) G. Ei-
senbrand, W. Tang, Handbook of Chinese Medicinal Plants: Chemistry,
Pharmacology, Toxicology, Wiley-VCH, Weinheim, 2010; c) J. M. Korn-
probst, Encyclopedia of Marine Natural Products, Wiley-VCH, Weinheim,
2010; d) G. Brahmachari, Handbook of Pharmaceutical Natural Products,
Wiley-VCH, Weinheim, 2010; e) S. C. Sweetman, Martindale: The Com-
plete Drug Reference, Pharmaceutical Press, London, 2011.
[9] a) M. Bauer, A. Haas, H. Muth, J. Fluorine Chem. 1980, 16, 129–136; b) H.
Bayreuther, A. Haas, Chem. Ber. 1973, 106, 1418–1422; c) K. Bogdano-
wicz-Szwed, B. Kawałek, M. Lieb, J. Fluorine Chem. 1987, 35, 317–327;
d) A. Kolasa, J. Fluorine Chem. 1987, 36, 29–40; e) S. Munavalli, D. K.
Rohrbaugh, D. I. Rossman, W. G. Wagner, H. D. Durst, Phosphorus Sulfur
and Silicon and the Related Elements 2002, 177, 1021–1031; f) V. I.
Popov, A. Haas, M. Lieb, J. Fluorine Chem. 1990, 47, 131–136; g) W. Zan-
kowska-Jasinska, B. Zaleska, A. Haas, J. Fluorine Chem. 1984, 24, 363–
368.
Scheme 4. a-trifluoromethylthiolation of silyl enol ethers. Yields shown were
determined by 19F NMR spectroscopy using PhOCF3 as an internal standard.
TBAF=tetrabutylammonium fluoride.
With silyl enol ethers of ketones, the bistrifluoromethylthio-
lated products, 6, are always formed. In particular, with tetra-
lone or cyclohexanone the bis-adducts, 6g and 6h, can be pre-
dominantly, or exclusively, obtained, whereas under the previ-
ous basic conditions, specific conditions were required for the
formation of 6g, and 6h was never formed. Such results could
be explained by the generation, during the reaction, of a tetra-
butylammonium sulfonamide (8-NBu4), which should be more
basic than 8-Li, generated during the previous reactions, and
should consequently favor the second deprotonation of the
mono-adducts (7). Danishefsky’s diene can also react under
these conditions to furnish bistrifluoromethylthiolated product
6u. The silyl enol ether of an aldehyde was successfully tri-
fluoromethylthiolated, whereas the more reactive enolate
failed under previous conditions, allowing the formation of
a-CF3S aldehyde 7v.
To conclude, we have described a general method to obtain
a large variety of a-trifluoromethylthiolated carbonyl com-
pounds by using a second generation of trifluoromethanesul-
fenamide (1b). This method allows the synthesis of valuable
building blocks for further syntheses, and can be also applied
to more elaborate substrates for a late trifluoromethylthiola-
tion (see 7r–t). Although in some cases, bistrifluoromethylthio-
lated compounds have been formed, such relatively unknown
compounds can also present some interest for further applica-
tions. The study of the reactivity of the new reagent (1b) is un-
derway and will be published in due course.
[10] E. C. Stump, Chem. Eng. News 1967, 45, 44.
[11] a) T. Bootwicha, X. Liu, R. Pluta, I. Atodiresei, M. Rueping, Angew. Chem.
2013, 125, 13093–13097; Angew. Chem. Int. Ed. 2013, 52, 12856–12859;
b) Q.-H. Deng, C. Rettenmeier, H. Wadepohl, L. H. Gade, Chem. Eur. J.
2014, 20, 93–97; c) X. Shao, X. Wang, T. Yang, L. Lu, Q. Shen, Angew.
Chem. 2013, 125, 3541–3544; Angew. Chem. Int. Ed. 2013, 52, 3457–
3460; d) E. V. Vinogradova, P. Mꢂller, S. L. Buchwald, Angew. Chem. 2014,
126, 3189–3192; Angew. Chem. Int. Ed. 2014, 53, 3125–3128; e) X.
Wang, T. Yang, X. Cheng, Q. Shen, Angew. Chem. 2013, 125, 13098–
Acknowledgements
We thank B. Fenet (University NMR Centre) for his help in the
determination of diastereomer configurations. The CNRS and
&
&
Chem. Eur. J. 2014, 20, 1 – 6
www.chemeurj.org
4
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

Communication
13102; Angew. Chem. Int. Ed. 2013, 52, 12860–12864; f) Y.-D. Yang, A.
Azuma, E. Tokunaga, M. Yamasaki, M. Shiro, N. Shibata, J. Am. Chem.
Soc. 2013, 135, 8782–8785.
[17] a) A. Ferry, T. Billard, B. R. Langlois, E. Bacquꢀ, Angew. Chem. 2009, 121,
8703–8707; Angew. Chem. Int. Ed. 2009, 48, 8551–8555; b) F. Baert, J.
Colomb, T. Billard, Angew. Chem. 2012, 124, 10528–10531; Angew.
Chem. Int. Ed. 2012, 51, 10382–10385; c) A. Ferry, T. Billard, E. Bacquꢀ,
B. R. Langlois, J. Fluorine Chem. 2012, 134, 160–163; d) S. Alazet, K. Ol-
livier, T. Billard, Beilstein J. Org. Chem. 2013, 9, 2354–2357; e) S. Alazet,
L. Zimmer, T. Billard, Angew. Chem. 2013, 125, 11014–11017; Angew.
Chem. Int. Ed. 2013, 52, 10814–10817.
[12] a) M. Rueping, X. Liu, T. Bootwicha, R. Pluta, C. Merkens, Chem.
Commun. 2014, 50, 2508–2511; b) X.-L. Zhu, J.-H. Xu, D.-J. Cheng, L.-J.
Zhao, X.-Y. Liu, B. Tan, Org. Lett. 2014, 16, 2192–2195.
[13] a) M. Hu, J. Rong, W. Miao, C. Ni, Y. Han, J. Hu, Org. Lett. 2014, 16,
2030–2033; b) X. Wang, Y. Zhou, G. Ji, G. Wu, M. Li, Y. Zhang, J. Wang,
Eur. J. Org. Chem. 2014, 3093–3096.
[18] F. G. Bordwell, Acc. Chem. Res. 1988, 21, 456–463.
[14] S.-G. Li, S. Z. Zard, Org. Lett. 2013, 15, 5898–5901.
[15] a) K. Kang, C. Xu, Q. Shen, Org. Chem. Front. 2014, 1, 294–297; b) R.
Pluta, P. Nikolaienko, M. Rueping, Angew. Chem. 2014, 126, 1676–1679;
Angew. Chem. Int. Ed. 2014, 53, 1650–1653.
Received: May 5, 2014
[16] A. Ferry, T. Billard, B. R. Langlois, E. Bacque, J. Org. Chem. 2008, 73,
9362–9365.
Published online on && &&, 0000
Chem. Eur. J. 2014, 20, 1 – 6
www.chemeurj.org
5
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
&
These are not the final page numbers! ÞÞ

Communication
COMMUNICATION
The next generation: A new reagent,
which is more reactive than previous re-
agents, has been designed to perform
trifluoromethylthiolation of a wide
range of carbonyl compounds (see
figure).
&
Synthetic Methods
S. Alazet, L. Zimmer, T. Billard*
&& – &&
Electrophilic Trifluoromethylthiolation
of Carbonyl Compounds
&
&
Chem. Eur. J. 2014, 20, 1 – 6
www.chemeurj.org
6
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!