Copper-Promoted Trifluoromethanesulfonylation and Trifluoromethylation of Arenediazonium Tetrafluoroborates with NaSO2CF3

Article abstract of DOI:10.1021/acs.joc.5b01295

A tunable chemoselective trifluoromethanesulfonylation and trifluoromethylation of arenediazonium tetrafluoroborates with Langlois' reagent (NaSO₂CF₃) was developed. The Cu₂O-catalyzed reaction in DMSO gave aryl trifluoromethanesulfones as the major products. On the other hand, the trifluoromethylated arenes were produced in the presence of oxidant tert-butyl hydroperoxide, CuBF₄(MeCN)₄, and 2,2′;6′,2 terpyridine (tpy). Both of these transformations proceed under mild conditions and tolerate functional groups.

Full text of DOI:10.1021/acs.joc.5b01295

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The Journal of Organic Chemistry
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CopperꢀPromoted Trifluoromethanesulfonylation
and Trifluoromethylation of Arenediazonium
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Tetrafluoroborates with NaSO2CF3
Ke Zhang,† XiuꢀHua Xu*,‡ and FengꢀLing Qing*,†,‡
†College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, 2999 North
Renmin Lu, Shanghai 201620, China
‡Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese
Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China
Eꢀmail: flq@mail.sioc.ac.cn, xuxiuhua@sioc.ac.cn
Table of Graphic Contents
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Abstract
A tunable chemoselective trifluoromethanesulfonylation and trifluoromethylation of arenediazonium
tetrafluoroborates with Langlois reagent (NaSO2CF3) was developed. The Cu2Oꢀcatalyzed reaction in
DMSO gave aryl trifluoromethanesulfones as the major products. On the other hand, the
trifluoromethylated arenes were produced in the presence of oxidant tꢀbutyl hydroperoxide,
CuBF4(MeCN)4 and 2,2′;6′,2′′ꢀterpyridine (tpy). Both of these transformations proceed under mild
conditions and tolerate functional groups.
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Introduction
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Incorporation of fluorineꢀcontaining groups into aromatic compounds is extremely important in
pharmaceutical and agrochemical industries, because fluorineꢀcontaining groups could impart unique
chemical and physical properties to aromatic compounds including improved metabolic stability, higher
lipophilicity and better bioavailability.1 Consequently, the preparation of fluorinated aromatic
compounds has attached continuous interest in organic synthesis. Recently, tremendous new synthetic
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methods
have
been
developed,
mainly
involving
transitionꢀmetalꢀcatalyzed/mediated
fluorination/fluoroalkylation reactions.2 The Sandmeyer reaction is widely used for the preparation of
functionalized arenes from aryl diazonium salts, which are easily accessible from commercially
available anilines.3 The transformation of anilines to aryl fluorides, named Balz–Schiemann reaction,4 is
a typical example (Scheme 1a). Very recently, the Sandmeyerꢀtype reactions have proven to be an
efficient strategy to introduce fluorineꢀcontaining groups, including trifluoromethyl (CF3),5
trifluoromethylthio (SCF3),6 difluoromethyl (CF2H),7 difluoromethylthio (SCF2H),8 and perfluoroalkyl
(RF),9 into the aromatic rings (Scheme 1b). Inspired by these advances, we wondered if aryl
trifluoromethanesulfones (ArSO2CF3) could be prepared from aryl diazonium salts.
Aryl trifluoromethanesulfones are important structural motifs frequently found in bioactive
compounds,10 chiral catalysts,11 and functional materials12 taking the advantages of the unique properties
of trifluoromethanesulfonyl group (SO2CF3).13 For more than half a century, various methods have been
developed for the preparation of these compounds.2w,14 Among them, the electrophilic and nucleophilic
trifluoromethanesulfonylation (triflylation) of aromatic substrates provided the most direct approaches to
aryl trifluoromethanesulfones. However, the electrophilic triflylation suffered from the narrow substrate
scope and low reaction yields.15 Recently, Avdeenko,16a Shekhar,16b and Singh16c reported the
nucleophilic triflylation of several types of substrates with Langlois reagent (NaSO2CF3) (Scheme 1c).
However, these substrates were not easily available. Herein, we disclose the efficient synthesis of aryl
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trifluoromethanesulfones from the Sandmeyerꢀtype triflylation of easily available aryl diazonium
tetrafluoroborates with NaSO2CF3 (Scheme 1d). This protocol boasts high levels of reactivity and site
selectivity.
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It was noteworthy that at the beginning NaSO2CF3 was developed by Langlois as a
trifluoromethylating reagent.17 In the presence of an oxidant such as tꢀbutyl hydroperoxide (TBHP), the
CF3 radical was generated from NaSO2CF3 and then reacted with electronꢀrich arenes and alkenes.18
Because of the electrophilic nature of CF3 radical, the trifluoromethylation of electronꢀpoor arenes with
NaSO2CF3 has been less explored. In continuous of our recent research interest in trifluoromethylation,19
we also want to report here the copperꢀmediated Sandmeyerꢀtype trifluoromethylation of both electronꢀ
rich and electronꢀdeficient aryl diazonium derivatives with NaSO2CF3 in the presence of TBHP (Scheme
1e). Although the Sandmeyer trifluoromethylation has been independently reported by Fu,5a Wang,5b and
Gooßen5c in 2013 (Scheme 1f), they employed either costly Umemoto reagent or in situ generated
moistureꢀsensitive [AgCF3] and [CuCF3] as trifluoromethyl sources.
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Scheme 1 Preparation of fluorinated aromatic compounds
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Results and Discussion
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We initially investigated the reaction of 4ꢀ(ethoxycarbonyl)benzenediazonium tetrafluoroborate 1a
and NaSO2CF3 in MeCN under N2 atmosphere at room temperature. The trifluoromethanesulfonylated
(triflylated) product 2a was formed in only 3% yield (Table 1, entry 1). A patent also disclosed that the
reaction of 1a with KSO2CF3 in MeCN gave 2a in low yield.20 Inspired by Shekhar’s triflylation
method,16b the addition of Cu2O to the reaction mixture afforded 2a in 20% yield along with the
trifluoromethylated product 3a in 23% yield (entry 2). With these initial results in hand, we continued to
optimize of reaction conditions for selective formation of 2a and 3a. Slightly lower yield of 2a was
observed in DMF, while the yield was sharply increased to 54% in DMSO (entries 3 and 4). Compound
3a was not detected in DMF or DMSO. Other copper salts, including CuTC, CuCN, and Cu(OAc)2,
were then screened (entries 5ꢀ7). However, none of them gave better results. To our delight, the yield of
2a (54%) in the presence of the catalytic amount of Cu2O (10 mol%) was the similar to that of the
stoichiometric amount of Cu2O (entry 8). Finally, the yield of 2a was improved to 62% when 3.0 equiv.
of NaSO2CF3 was used (entry 9).
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Table 1. Optimization of reaction conditionsa
O O
N2+
-
S
Cu salt, ligand
oxidant
CF3
CF3
+
NaSO2CF3
+
BF4
solvent, rt
EtO2C
EtO2C
EtO2C
1a
2a
3a
Entry
Cu salt
ligand
oxidant
Solvent
additive
yield (2a/3a, %)b
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2
3
4
5
MeCN
MeCN
DMF
3/0
─
─
─
─
─
─
─
─
─
─
─
─
─
─
─
─
Cu2O
Cu2O
Cu2O
CuTC
20/23
14/0
54/0
45/0
DMSO
DMSO
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CuCN
DMSO
DMSO
DMSO
DMSO
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
33/0
33/0
53/0
62/0
0/11
0/10
0/15
0/trace
0/9
─
─
─
─
─
─
─
─
─
─
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7
8c
9c,d
Cu(OAc)2
Cu2O
─
─
─
─
Cu2O
─
─
10
Cu2O
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
─
9
11
CuTc
─
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CuBF4(MeCN)4
Cu(OAc)2
─
13
─
14
CuBF4(MeCN)4 Py
CuBF4(MeCN)4 Bipy
CuBF4(MeCN)4 Phen
CuBF4(MeCN)4 Tpy
CuBF4(MeCN)4 Tpy
CuBF4(MeCN)4 Tpy
CuBF4(MeCN)4 Tpy
CuBF4(MeCN)4 Tpy
CuBF4(MeCN)4 Tpy
─
15
0/5
─
16
0/4
─
17
0/24
0/35
0/47
0/14
0/53
0/59
0/65
─
18d
19d,e
20d,e
21d,e
22d,e,f
─
─
TEA
NaHCO3
NaHCO3
NaHCO3
23d,e,f,g CuBF4(MeCN)4 Tpy
aReaction conditions: 1a (0.1 mmol), NaSO2CF3 (0.15 mmol), metal salt (0.1 mol), solvent (2.0 mL), room
temperature, under N2, overnight. Yield determined by 19F NMR spectroscopy using trifluoromethoxybenzene as an
internal standard. c10 mol % Cu2O was used. d3.0 equiv. of NaSO2CF3 was used. e2.0 equiv. of CuBF4(MeCN)4 and 2.0
equiv. of ligand were added. fH2O (0.1 mL) was added. g The reaction temperature was 45 oC.
b
After obtaining the optimal reaction conditions for trifluoromethanesulfonylation, we then focused on
the exploration of trifluoromethylation. It is well known that NaSO2CF3 easily reacts with TBHP to
generate the CF3 radical. Thus, TBHP was added to the reaction mixture to accelerate the decomposition
of NaSO2CF3. As we expected, the formation of 2a was totally inhibited, but the trifluoromethylated
compound 3a was formed in low yield (entry 10). Among the different copper salts evaluated,
CuBF4(MeCN)4 proved to be more efficient than Cu2O, CuTC, and Cu(OAc)2 (entries 11ꢀ13). Notably,
the coordination of the ligand to copper is important to trifluoromethylation. Neither the monodentate
ligand pyridine (py) nor the bidentate ligands 2,2′ꢀbipyridine (bipy) and 1,10ꢀphenanthroline (phen) was
effective (entries 14ꢀ16). To our delight, the tridentate ligand 2,2′;6′,2′′ꢀterpyridine (tpy) had a beneficial
effect on the reactivity, producing 3a in 24% yield (entry 17). Increasing the amount of NaSO2CF3,
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CuBF4(MeCN)4 and tpy improved the yield of 3a to 47% (entries 18 and 19). A poor yield (14%) of 3a
was obtained when triethylamine (TEA) was added (entry 20). In contrast, a slightly higher yield was
gained when NaHCO3 was used as the additive (entry 21). The yield of 3a was further improved to 59%
using small amount of water (0.1 mL) as the coꢀsolvent (entry 22). Finally, the screening of reaction
temperature revealed that compound 3a was formed in highest yield (65%) when the reaction was
conducted at 45 oC (entry 23).
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With the optimized reaction conditions established, we first explored the substrate scope of copperꢀ
catalyzed trifluoromethanesulfonylation of arenediazonium tetrafluoroborates (Scheme 2). In general,
the arenediazonium salts 1 bearing electronꢀwithdrawing groups reacted efficiently to afford the
corresponding triflylated products 2 in moderate to excellent yields. However, the electronꢀdonating
groupꢀbearing substrates led to much lower yields, probably due to the lack of the nucleophilicity of
these arenediazonium salts. The substituents, such as ester, carboxylic acid, nitrile, ketone, sulfonamide
and nitro groups, at different positions of the aromatic ring were all well tolerated (2aꢀ2k). Diꢀ and triꢀ
substituted arenediazonium salts 1lꢀ1p were also compatible under the standard reaction conditions. It
was noteworthy that quinoline derivative 1q proceeded smoothly to give heteroaryl
trifluoromethanesulfone 2q in 45% yield.
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N2+
-
SO2CF3
SO2CF3
1
2
3
4
Cu2O (10 mol %)
+
NaSO2CF3
R
R
DMSO, rt
BF4
1
2
SO2CF3
SO2CF3
5
6
NC
7
8
9
EtO2C
Ac
HO2C
2c, 90%
SO2CF3
2a, 60%
SO2CF3
2b, 52%
SO2CF3
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F3C
Bz
2f, 58%
SO2CF3
2d, 61%
SO2CF3
2e, 70%
SO2CF3
O2N
O2N
NO2
2i, 85%
2g, 61%
2h, 45%
SO2CF3
H
SO2CF3
N
S
O O
O2N
2j, 70%
SO2CF3
2k, 59%
SO2CF3
F3C
Cl
Cl
SO2CF3
O2N
Me
2n, 82%
O2N
2l, 54%
SO2CF3
2m, 65%
Br
SO2CF3
Cl
SO2CF3
O2N
Cl
2o, 65%
O2N
N
2p, 51%
2q, 45%
Scheme 2. Substrate scope of copperꢀcatalyzed trifluoromethanesulfonylation of arenediazonium
tetrafluorobroates. Reaction conditions: 1 (0.2 mmol), NaSO2CF3 (0.6 mmol), Cu2O (0.02 mmol),
DMSO (2.0 mL), room temperature, under N2, overnight. Yields are those of the isolated products.
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Then, the substrate scope of copperꢀmediated trifluoromethylation of arenediazonium
tetrafluoroborates was also investigated. As shown in Scheme 3, a range of arenediazonium
tetrafluoroborates 1 were subjected to the reaction conditions, producing the trifluoromethylated arenes
3 in acceptable yields. The mild reaction conditions allowed the tolerance of electronꢀwithdrawing
groups such as ester (3a and 3s), nitrile (3c), ketones (3d and 3e), nitro group (3g) and sulfonate (3r) as
well as electronꢀdonating groups including aryl group (3t) and amine (3u). Notably, the bromoꢀ
containing substrates (1v and 1w) are also suitable substrates for the reaction, enabling further
functionalization.
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Scheme 3. Substrate scope of copperꢀmediated trifluoromethylation of arenediazonium
tetrafluorobroates. Reaction conditions: 1 (0.2 mmol), NaSO2CF3 (0.6 mmol), CuBF4(MeCN)4 (0.4
mmol), Tpy (0.4 mmol), MeCN/H2O (2.0 mL/0.1 mL), 45 C, under N2, overnight. Yields are those of
o
the isolated products.
A preliminary mechanistic investigation was carried out to understand the trifluoromethylation of
arenediazonium tetrafluoroborates using NaSO2CF3 as trifluoromethyl source. Under the standard
conditions, a radical clock substrate 1y was transformed into cyclized product 4 in 84% yield (Scheme
4a). This result revealed that radical process was involved in this transformation. Furthermore, the
trifluoromethylation reaction was monitored by 19F NMR spectroscopy (see the Supporting Information).
When TBHP was added to the mixture of CuBF4(MeCN)4, NaSO2CF3, and Tpy in MeCN, NaSO2CF3
was totally converted into CuCF3 species. Then treatment of CuCF3 species with arenediazonium
tetrafluoroborate 1w gave trifluoromethylated product 3w in 43 % yield (Scheme 4b).
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CF3
(a)
N2+
O
CuBF4(MeCN)4,Tpy
TBHP
MeCN/H2O, 45 oC
1
2
3
4
-
BF4
+ NaSO2CF3
O
1y
4, 84%
5
6
7
8
N2+
-
CuBF4(MeCN)4
BF4
CF3
(b)
Br
+
TBHP
9
[CuCF3]
species
1w
NaSO2CF3
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14
15
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17
18
19
+
Tpy
Br
3w, 43%
Scheme 4. Mechanistic experiments.
On the basis of the above experimental results, a plausible mechanism of this Sandmeyer
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trifluoromethylation was shown in Scheme 5. The Cu(I) species transferred a single electron to
diazonium salt A to give diazo radical B, which released nitrogen gas with the formation of an aryl
radical C. On the other hand, tꢀBuOOH was transformed into tꢀBuO radical in the presence of Cu(I)
species. Then the reaction of tꢀBuO radical with NaSO2CF3 gave CF3 radical, which reacted with Cu(I)
species to afford the corresponding Cu(II) species D. Finally, the aryl radical C abstracted the CF3 group
from intermediate D to give trifluoromethylated arenes and the Cu(I) species.5c,6b,7,8 As the reaction of
NaSO2CF3 and tꢀBuOOH in presence of Cu salt released CF3 radical rapidly,19f,i the excess amounts of
CuBF4(MeCN)4 and tpy were required to stabilize the CF3 radical in this reaction process.
Scheme 5. Proposed mechanism.
Conclusion
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We have developed
a
tunable copperꢀpromoted trifluoromethanesulfonylation and
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trifluoromethylation of arenediazonium tetrafluoroborates with Langlois reagent by appropriate choice
of the reaction conditions. The triflylation strategy is an important complement to the previously
reported triflylation methods, while the employment of stable and inexpensive NaSO2CF3 as the CF3
source is a valuable extension of the Sandmeyer trifluoromethylation. A variety of functional groups are
well tolerated in these transformations. Thus, these protocols provide an alternative approach for the
preparation of both aryl trifluoromethanesulfones and trifluoromethylated arenes. Work is ongoing to
develop conditions for triflylation of electronꢀrich arenediazonium salts and to reduce the amounts of Cu
salt and ligand in Sandmeyer trifluoromethylation reaction.
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Experimental Section
1
General Experimental Methods. H NMR (TMS as the internal standard), 19F NMR spectra (CFCl3 as
the outside standard and low field is positive), and 13C NMR were recorded on a 400 MHz spectrometer.
Chemical shifts (δ) are reported in ppm, and coupling constants (J) are in Hertz (Hz). The following
abbreviations were used to explain the multiplicities: s = singlet, d = doublet, t = triplet, q = quartet, m =
multiplet. HRMS using ESI were obtained on a ESIꢀFTMS mass spectrometer, HRMS using EI were
obtained on a GCꢀTOF mass spectrometer. The diazonium salts were prepared from the corresponding
anilines following the procedures below and were directly used. Sodium trifluoromethanesulfinate
(NaSO2CF3, 95%) was purchased from TCI and used without further purification. All other starting
materials were purchased from commercial sources and used as received. Unless otherwise noted, all
reagents were obtained commercially and used without further purification. 2a,16b 2b,21 2c,14f 2d,22 2e,23
2f,16b 2g,16b 2h,14f 2i,24 3a,5b 3c,5c 3d,25 3e,5a 3g,26 3r,5b 3s,5b 3t,27 3u,5c 3v,28 3w5b, 3x5b are all known
compounds.
General procedure for the synthesis of arenediazonium tetrafluoroborates
Procedure A5c In a 50 mL roundꢀbottom flask, the aniline (10.0 mmol) was dissolved in a mixture of
absolute ethanol (3.0 mL) and an aqueous solution of HBF4 (40%, 3.1 mL, 20.0 mmol). Tertꢀbutyl
o
nitrite (2.7 mL, 20 mmol) was added dropwise by a syringe to the solution at 0 C. The reaction was
stirred at room temperature for 1 h and diethyl ether (20 mL) was added to precipitate the
arenediazonium tetrafluoroborate. Then the mixture was filtered off and washed with diethyl ether (3 ×
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10 mL). The arenediazonium tetrafluoroborate was dried in vacuo for 30 minutes and used without
further purification.
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3
Procedure B5a To a 50 mL roundꢀbottom flask containing HCl (6 mL) and H2O (6 mL) was added
aniline (25.0 mmol). Aniline hydrochloride crystals were formed at 0−5 oC, and then sodium nitrite
(1.79 g, 26.0 mmol) in H2O (4 mL) was added dropwise, followed by addition of sodium
tetrafluoroborate (3.95 g, 36.0 mmol) in H2O (8 mL). The reaction mixture was allowed to stir for
another 10 min at 5 oC. The arenediazonium salt solid was filtered off and then washed with 5% sodium
tetrafluoroborate (3 × 10 mL), followed by methanol (2 × 15 mL). The crude product was purified by
recrystallization with acetone and cold diethyl ether. The obtained arenediazonium tetrafluoroborate was
dried in vacuo for 30 minutes and used without further purification.
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General procedure for trifluoromethanesulfonylation of arenediazonium tetrafluoroborate
A 25 mL Schlenk tube equipped with a magnetic stir bar was charged with arenediazonium
tetrafluoroborate (0.2 mmol, 1.0 eq.), Cu2O (2.8 mg, 0.02 mmol, 0.1 eq.) and NaSO2CF3 (99.2 mg, 0.6
mmol, 3.0 eq.). The tube was sealed with a septum, evacuated and backfilled with nitrogen for three
times. Then DMSO (2.0 mL) was added by a syringe. The mixture was stirred at room temperature
overnight. Then the reaction mixture was diluted with ethyl acetate (20 mL) and washed with water (15
mL). The combined organic phase was washed with brine, dried over Na2SO4, filtered, and concentrated
under reduced vacuum. The residue was purified by silica gel column chromatography to provide the
desired product.
Ethyl 4-(trifluoromethylsulfonyl)benzoate (2a) Compound 2a was prepared following the general
procedure, starting from 4ꢀ(ethoxycarbonyl)benzenediazonium tetrafluoroborate (52.8 mg, 0.2 mmol)
prepared by procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl
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acetate (10/1) as the eluent, compound 2a was obtained as a white solid (34.5 mg, 60%), mp 46ꢀ48 C.
1H NMR (400 MHz, CDCl3) δ ppm 8.32 (d, J = 8.6 Hz, 2H), 8.13 (d, J = 8.3 Hz, 2H), 4.45 (q, J = 7.1
Hz, 2H), 1.43 (t, J = 7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ ppm 164.4, 137.8, 134.9, 130.8, 130.8,
119.7 (q, JCꢀF = 323.8 Hz), 62.2, 14.2. 19F NMR (376 MHz, CDCl3) δ ppm ꢀ78.09 (s, 3F). MS (EI): m/z
282 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C10H9F3O4S 282.0174; Found: 282.0173.
4-(Trifluoromethylsulfonyl)benzoic acid (2b) Compound 2b was prepared following the general
procedure, starting from 4ꢀcarboxybenzenediazonium tetrafluoroborate (47.2 mg, 0.2 mmol) prepared by
procedure A. After purification by silica gel column chromatography using dichloromethane/methanol
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(20/1) as the eluent, compound 2b was obtained as a white solid (27.1 mg, 52%), mp 250ꢀ255 C. H
NMR (400 MHz, CD3OD) δ ppm 8.39 – 8.27 (m, 2H), 8.18 (d, J = 8.3 Hz, 2H). 13C NMR (100 MHz,
CD3OD) δ ppm 165.8, 138.6, 134.5, 130.8, 130.8, 119.8 (q, JCꢀF = 325.2 Hz). 19F NMR (376 MHz,
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CD3OD) δ ppm ꢀ77.95 (s, 3F). IR (ATR): νmax 3101, 2853, 1697, 1370, 1287, 1204, 1218, 1141, 721,
623, 579 cmꢀ1. MS (EI): m/z 254 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C8H5F3O4S 253.9861;
Found: 253.9855.
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4-(Trifluoromethylsulfonyl)benzonitrile (2c) Compound 2c was prepared following the general
procedure, starting from 4ꢀcyanobenzenediazonium tetrafluoroborate (43.4 mg, 0.2 mmol) prepared by
procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
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(20/1) as the eluent, compound 2c was obtained as a white solid (42.3 mg, 90 %), mp 90ꢀ92 C. H
NMR (400 MHz, CDCl3) δ ppm 8.19 (d, J = 8.4 Hz, 2H), 7.99 (d, J = 8.4 Hz, 2H). 13C NMR (100 MHz,
CDCl3) δ ppm 135.5, 133.5, 131.4, 120.4, 119.5 (q, JCꢀF = 323.9 Hz), 116.5. 19F NMR (376 MHz,
CDCl3) δ ppm ꢀ77.68 (s, 3F). MS (EI): m/z 235 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for
C8H4F3NO2S 234.9915; Found: 234.9911.
1-(4-(Trifluoromethylsulfonyl)phenyl)ethan-1-one (2d) Compound 2d was prepared following the
general procedure, starting from 4ꢀacetylbenzenediazonium tetrafluoroborate (46.8 mg, 0.2 mmol)
prepared by procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl
acetate (10/1) as the eluent, compound 2d was obtained as a white solid (30.8 mg, 61 %), mp 54ꢀ56 oC.
1H NMR (400 MHz, CDCl3) δ ppm 8.27 – 7.95 (m, 4H), 2.68 (s, 3H). C NMR (100 MHz, CDCl3) δ
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ppm 196.3, 143.0, 134.9, 131.2, 129.4, 119.6 (q, JCꢀF = 324.00 Hz), 26.9. 19F NMR (376 MHz, CDCl3) δ
ppm ꢀ78.05 (s, 3F). MS (EI): m/z 252 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C9H7F3O3S
252.0068; Found: 252.0070.
Phenyl(4-(trifluoromethylsulfonyl)phenyl)methanone (2e) Compound 2e was prepared following the
general procedure, starting from 4ꢀbenzoylbenzenediazonium tetrafluoroborate (59.2 mg, 0.2 mmol)
prepared by procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl
acetate (10/1) as the eluent, compound 2e was obtained as a white solid (44.0 mg, 70 %), mp 92ꢀ93 oC.
1H NMR (400 MHz, CDCl3) δ ppm 8.18 (d, J = 8.2 Hz, 2H), 8.07 – 7.97 (m, 2H), 7.90 – 7.75 (m, 2H),
7.71 – 7.63 (m, 1H), 7.54 (t, J = 7.7 Hz, 2H). 13C NMR (100 MHz, CDCl3) δ ppm 194.6, 144.8, 135.9,
134.2, 133.8, 130.9, 130.7, 130.2, 128.8, 119.7 (q, JCꢀF = 324.1 Hz). 19F NMR (376 MHz, CDCl3) δ ppm
ꢀ77.99 (s, 3F). MS (EI): m/z 314 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C14H9F3O3S 314.0224;
Found: 314.0229.
1-(Trifluoromethyl)-4-(trifluoromethylsulfonyl)benzene (2f) Compound 2f was prepared following the
general procedure, starting from 4ꢀ(trifluoromethyl)ꢀbenzenediazonium tetrafluoroborate (52.0 mg, 0.2
mmol) prepared by procedure A. After purification by silica gel column chromatography using nꢀ
hexane/ethyl acetate (20/1) as the eluent, compound 2f was obtained as a white solid (33.1 mg, 58 %),
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mp 38ꢀ40 oC. 1H NMR (400 MHz, CDCl3) δ ppm 8.21 (d, J = 8.2 Hz, 2H), 7.96 (d, J = 8.2 Hz, 2H). 13C
NMR (100 MHz, CDCl3) δ ppm 138.0 (q, J = 33.7 Hz), 135.1, 131.5, 127.0 (q, J = 3.7 Hz), 122.7 (q, JCꢀ
F = 273.5 Hz), 119.62 (q, JCꢀF = 326.3 Hz). 19F NMR (376 MHz, CDCl3) δ ppm ꢀ63.62 (s, 3F), ꢀ77.95 (s,
3F). MS (EI): m/z 278 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C8H4F6O2S 277.9836; Found:
277.9831.
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1-Nitro-4-(trifluoromethylsulfonyl)benzene (2g) Compound 2g was prepared following the general
procedure, starting from 4ꢀnitrobenzenediazonium tetrafluoroborate (47.4 mg, 0.2 mmol) prepared by
procedure B. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
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(20/1) as the eluent, compound 2g was obtained as a white solid (31.2 mg, 61 %), mp 85ꢀ86 C. H
NMR (400 MHz, CDCl3) δ ppm 8.52 (d, J = 8.7 Hz, 2H), 8.28 (d, J = 8.6 Hz, 2H). 13C NMR (100 MHz,
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CDCl3) δ ppm 152.5, 137.0, 132.4, 125.0, 119.5 (q, JCꢀF = 326.0 Hz). F NMR (376 MHz, CDCl3) δ
ppm ꢀ77.57 (s, 3F). MS (EI): m/z 255 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C7H4F3NO4S
254.9813; Found: 254.9812.
1-Nitro-3-(trifluoromethylsulfonyl)benzene (2h) Compound 2h was prepared following the general
procedure, starting from 3ꢀnitrobenzenediazonium tetrafluoroborate (47.4 mg, 0.2 mmol) prepared by
procedure B. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
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(20/1) as the eluent, compound 2h was obtained as a yellow oil (23.2 mg, 45 %). H NMR (400 MHz,
CDCl3) δ ppm 8.89 (t, J = 2.0 Hz, 1H), 8.71 (dd, J = 8.3, 1.9 Hz, 1H), 8.45 – 8.32 (m, 1H), 7.96 (t, J =
8.0 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ ppm 148.7, 136.0, 133.7, 131.6, 131.0, 125.9, 119.5 (q, JCꢀF
= 325.8 Hz). 19F NMR (376 MHz, CDCl3) δ ppm ꢀ77.57 (s, 3F). MS (EI): m/z 255 [M+]. HRMS (EIꢀ
TOF): m/z [M+] Calcd for C7H4F3NO4S: 254.9813; Found: 254.9817.
1-Nitro-2-(trifluoromethylsulfonyl)benzene (2i) Compound 2i was prepared following the general
procedure, starting from 2ꢀnitrobenzenediazonium tetrafluoroborate (47.4 mg, 0.2 mmol) prepared by
procedure B. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
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(20/1) as the eluent, compound 2i was obtained as a yellow oil (43.6 mg, 85 %). H NMR (400 MHz,
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CDCl3) δ ppm 8.25 – 8.21 (m, 1H), 7.92 – 7.97 (m, 1H), 7.92 – 7.86 (m, 2H). C NMR (100 MHz,
CDCl3) δ ppm 150.0, 137.8, 134.1, 132.9, 126.0 (q, JCꢀF = 2.2 Hz), 125.4, 119.8 (q, JCꢀF = 327.9 Hz).
19F NMR (376 MHz, CDCl3) δ ppm ꢀ73.39 (s, 3F). MS (EI): m/z 255 [M+]. HRMS (EIꢀTOF): m/z [M+]
Calcd for C7H4F3NO4S: 254.9813; Found: 254.9819.
1-Nitro-4-(trifluoromethylsulfonyl)naphthalene (2j) Compound 2j was prepared following the general
procedure, starting from 4ꢀnitronaphthaleneꢀ1ꢀdiazonium tetrafluoroborate (57.4 mg, 0.2 mmol)
prepared by procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl
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acetate (20/1) as the eluent, compound 2j was obtained as a yellow solid (42.7 mg, 45 %), mp 75ꢀ77 oC.
1H NMR (400 MHz, CDCl3) δ ppm δ 9.00 – 8.84 (m, 1H), 8.58 (d, J = 8.1 Hz, 1H), 8.32 (d, J = 8.3 Hz,
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1H), 8.12 (d, J = 8.1 Hz, 1H), 7.90 (m, 2H). C NMR (100 MHz, CDCl3) δ ppm 153.3, 133.9, 131.6,
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131.0, 130.5, 125.4, 124.9 (q, JCꢀF = 1.5 Hz), 123.6, 120.1, 120.0 (q, JCꢀF = 325.5 Hz). F NMR (376
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MHz, CDCl3) δ ppm ꢀ77.03 (s, 3F). IR (ATR): νmax 3098, 2927, 1534, 1364, 1209, 1108, 855, 804, 768,
621, 561 cmꢀ1. MS (EI): m/z 305 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C11H6F3NO4S: 304.9970;
Found: 304.9962.
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N-(p-tolyl)-4-(trifluoromethylsulfonyl)benzenesulfonamide (2k) Compound 2k was prepared following
the general procedure, starting from 4ꢀ(Nꢀ(pꢀtolyl)sulfamoyl)ꢀbenzenediazonium tetrafluoroborate (72.2
mg, 0.2 mmol) prepared by procedure A. After purification by silica gel column chromatography using
nꢀhexane/ethyl acetate (5/1) as the eluent, compound 2k was obtained as a white solid (44.8 mg, 59 %),
mp 131ꢀ135 oC. 1H NMR (400 MHz, CDCl3) δ ppm 8.11 (d, J = 8.2 Hz, 2H), 8.00 – 7.97 (m, 2H), 7.09
(d, J = 8.0 Hz, 2H), 6.95 (d, J = 7.9 Hz, 2H), 6.64 (s, 1H). 2.31 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
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ppm 146.8, 137.0, 135.4, 132.3, 131.5, 130.3, 128.6, 123.3, 119.6 (q, JCꢀF = 325.8 Hz), 20.9. F NMR
(376 MHz, CDCl3) δ ppm ꢀ77.78 (s, 3F). IR (ATR): νmax 3273, 3096, 1512, 1382, 1214, 1167, 1078,
927, 824, 635, 520 cmꢀ1. MS (EI): m/z 379 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C14H12F3NO4S2:
379.0160; Found: 379.0164.
1-Chloro-2-(trifluoromethyl)-4-(trifluoromethylsulfonyl)benzene (2l) Compound 2l was prepared
following the general procedure, starting from 4ꢀchloroꢀ3ꢀ(trifluoromethyl)benzenediazonium
tetrafluoroborate (58.9 mg, 0.2 mmol) prepared by procedure A. After purification by silica gel column
chromatography using nꢀhexane/ethyl acetate (20/1) as the eluent, compound 2l was obtained as a white
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solid (33.8 mg, 54 %), mp 36ꢀ38 C. 1H NMR (400 MHz, CDCl3) δ ppm 8.34 (s, 1H) , 8.16 (d, J = 8.2
Hz, 1H), 7.87 (d, J = 8.4 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ ppm 142.2, 134.7, 133.5, 130.8 (q, JCꢀ
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F = 32.9 Hz). 130.0 (q, JCꢀF = 5.4 Hz), 121.5 (q, JCꢀF = 274.2 Hz), 119.5 (q, JCꢀF = 325.8 Hz). F NMR
(376 MHz, CDCl3) δ ppm ꢀ63.36 (s, 3F), ꢀ77.78 (s, 3F). IR (ATR): νmax 3096, 1595, 1468, 1378, 1311,
1145, 1081, 837, 643, 580, 494 cmꢀ1. MS (EI): m/z 312 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for
C8H3ClF6O2S: 311.9446; Found: 311.9444.
2-Chloro-1-nitro-4-((trifluoromethyl)sulfonyl)benzene (2m) Compound 2m was prepared following
the general procedure, starting from 3ꢀchloroꢀ4ꢀnitrobenzenediazonium tetrafluoroborate (54.2 mg, 0.2
mmol) prepared by procedure A. After purification by silica gel column chromatography using nꢀ
hexane/ethyl acetate (20/1) as the eluent, compound 2m was obtained as a white solid (37.8 mg, 65 %),
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mp 58ꢀ60 C. H NMR (400 MHz, CDCl3) δ ppm 8.25 (d, J = 1.8 Hz, 1H), 8.11 (dd, J = 8.5, 1.8 Hz,
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1H), 8.07 (d, J = 8.4 Hz, 1H). C NMR (100 MHz, CDCl3) δ ppm 152.8, 135.8, 134.2, 130.1, 129.0,
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126.5, 119.4 (q, JCꢀF = 326.0 Hz). F NMR (376 MHz, CDCl3) δ ppm ꢀ77.24 (s, 3F). IR (ATR): νmax
3100, 3015, 1544, 1373, 1212, 1079, 169, 632, 491 cmꢀ1. MS (EI): m/z 289 [M+]. HRMS (EIꢀTOF): m/z
[M+] Calcd for C7H3ClF3NO4S: 288.9423; Found: 288.9426.
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2-Methyl-4-nitro-1-(trifluoromethylsulfonyl)benzene (2n) Compound 2n was prepared following the
general procedure, starting from 2ꢀmethylꢀ 4ꢀnitrobenzenediazonium tetrafluoroborate (50.2 mg, 0.2
mmol) prepared by procedure A. After purification by silica gel column chromatography using nꢀ
hexane/ethyl acetate (20/1) as the eluent, compound 2n was obtained as a white solid (44.4 mg, 82 %),
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mp 59ꢀ60 C. H NMR (400 MHz, CDCl3) 8.32 – 8.26 (m, 3H), 2.87 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ ppm 152.0, 144.7, 135.4, 135.0, 128.0, 121.9, 119.8 (q, JCꢀF = 326.4 Hz). 20.9. 19F NMR (376
MHz, CDCl3) δ ppm ꢀ77.50 (s, 3F). IR (ATR): νmax 3105, 3034, 1538, 1360, 1202, 1133, 1044, 901,
802, 697, 626, 581, 530 cmꢀ1. MS (EI): m/z 269 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for
C8H6F3NO4S: 268.9970; Found: 268.9973.
2-Chloro-4-nitro-1-(trifluoromethylsulfonyl)benzene (2o) Compound 2o was prepared following the
general procedure, starting from 2ꢀchloroꢀ4ꢀnitrobenzenediazonium tetrafluoroborate (54.2 mg, 0.2
mmol) prepared by procedure A. After purification by silica gel column chromatography using nꢀ
hexane/ethyl acetate (20/1) as the eluent, Compound 2o was obtained as a light yellow oil (37.9 mg,
65%). 1H NMR (400 MHz, CDCl3) δ ppm 8.49 (d, J = 2.1 Hz, 1H), 8.43 (d, J = 8.7 Hz, 1H), 8.37 (dd, J
= 8.8, 2.1 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ ppm 152.2, 137.8, 136.1, 135.5, 127.9, 122.4, 119.6
(q, JCꢀF = 326.9 Hz). 19F NMR (376 MHz, CDCl3) δ ppm ꢀ75.28(s, 3F). IR (ATR): νmax 3103, 1538,
1385, 1356, 1214, 1129, 898, 773, 683, 621, 577, 349 cmꢀ1. MS (EI): m/z 289 [M+]. HRMS (EIꢀTOF):
m/z [M+] Calcd for C7H3ClF3NO4S: 288.9423; Found:, 288.9428.
1-Bromo-3-chloro-5-nitro-2-(trifluoromethylsulfonyl)benzene (2p) Compound 2p was prepared
following the general procedure, starting from 2ꢀbromoꢀ6ꢀchloroꢀ4ꢀnitrobenzenediazonium
tetrafluoroborate (70.1 mg, 0.2 mmol) prepared by procedure A. After purification by silica gel column
chromatography using nꢀhexane/ethyl acetate (20/1) as the eluent, compound 2p was obtained as a white
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solid (38.3 mg, 51%), mp 72ꢀ75 C. H NMR (400 MHz, CDCl3) δ ppm 8.61 (d, J = 2.3 Hz, 1H), 8.42
(d, J = 2.3 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ ppm 150.0, 141.3, 135.1, 130.5, 128.3, 127.3, 119.6
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(q, JCꢀF = 328.5 Hz). F NMR (376 MHz, CDCl3) δ ppm ꢀ74.77 (s, 3F). R (ATR): νmax 3088, 2921,
1538, 1395, 1344, 1223, 1130, 1101, 779, 739, 624, 579, 464 cmꢀ1. MS (EI): m/z 369 [M+]. HRMS (EIꢀ
TOF): m/z [M+] Calcd for C7H2BrClF3NO4S: 366.8529; Found: 366.8531.
3-(Trifluoromethylsulfonyl)quinoline (2q) Compound 2q was prepared following the general
procedure, starting from quinolineꢀ3ꢀdiazonium tetrafluoroborate (48.6 mg, 0.2 mmol) prepared by
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procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate (5/1)
as the eluent, compound 2q was obtained as a white solid (24.3 mg, 45%), mp 67ꢀ69 oC. 1H NMR (400
MHz, CDCl3) δ ppm 9.33 (d, J = 2.3 Hz, 1H), 8.94 (d, J = 2.3 Hz, 1H), 8.29 (d, J = 8.4 Hz, 1H), 8.07 (d,
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J = 8.4 Hz, 1H), 8.05 – 8.01 (m, 1H), 7.83 – 7.78 (m, 1H). C NMR (100 MHz, CDCl3) δ ppm 150.9,
147.5, 142.0, 134.8, 130.0, 129.7, 129.2, 126.1, 124.5, 119.7 (q, JCꢀF = 325.2 Hz). 19F NMR (376 MHz,
CDCl3) δ ppm ꢀ78.16 (s, 3F). IR (ATR): νmax 3072, 2924, 1608, 1364, 1203, 1125, 1062, 838, 671, 576,
515 cmꢀ1. MS (EI): m/z 261 [M+]. HRMS (EIꢀTOF): m/z [M+] Calcd for C10H6F3NO2S: 261.0071;
Found: 261.0068.
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General procedure for trifluoromethylation of arenediazonium tetrafluoroborate with NaSO2CF3.
A 25 ml Schlenk tube equipped with a magnetic stir bar was charged with CuBF4(MeCN)4 (125.8 mg,
0.4 mmol, 2.0 eq.), Tpy (93.3 mg, 0.4 mmol, 2.0 eq.), NaHCO3 (33.6 mg, 0.4 mmol, 2.0 eq.) and
NaSO2CF3 (98.5 mg, 0.6 mmol, 3.0 eq.). The tube was sealed with a septum, evacuated and backfilled
with N2 for three times. Then MeCN (1.0 mL) and deionized water (0.1 mL) were added. The red brown
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mixture was stirred at 23 C for 5 min. Then TBHP (70 wt%, 138.7 mg, 1.0 mmol, 5.0 eq.) was added
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dropwise by a microsyringe. The reaction mixture was heated to 45 C. A solution of arenediazonium
tetrafluoroborate (0.2 mmol, 1.0 eq.) in MeCN (1.0 mL) was added dropwise by a syringe during 15
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min. Then the reaction mixture was stirred at 45 C for overnight. After that, saturated ammonium
chloride aqueous solution was added. The resulting mixture was filtered by Celite, eluted with diethyl
ether. The water phase was extracted with diethyl ether (2 × 15 mL). The combined organic phase was
washed with brine, dried over Na2SO4, filtered, and concentrated under reduced vacuum. The residue
was purified by silica gel column chromatography to provide the desired product.
Ethyl 4-(trifluoromethyl)benzoate (3a) Compound 3a was prepared following the general procedure,
starting from 4ꢀ(ethoxycarbonyl)benzenediazonium tetrafluoroborate (52.8 mg, 0.2 mmol) prepared by
procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
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(20/1) as the eluent, compound 3a was obtained as a light yellow oil (27.2 mg, 62%). H NMR (400
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MHz, CDCl3) 8.15 (d, J = 8.1 Hz), 7.69 (d, J = 8.1 Hz), 4.41 (q, J = 7.0 Hz), 1.41 (t, J = 7.1 Hz). C
NMR (100 MHz, CDCl3) δ ppm 165.4, 134.3 (q, JCꢀF = 32.7 Hz), 133.7, 129.9, 125.3 (d, JCꢀF = 3.7 Hz),
123.7 (q, JCꢀF = 272.7 Hz), 61.5, 14.2; 19F NMR (376 MHz, CDCl3) δ ppm ꢀ63.18 (s, 3F).
4-(Trifluoromethyl)benzonitrile (3c) Compound 3c was prepared following the general procedure,
starting from 4ꢀcyanobenzenediazonium tetrafluoroborate (43.8 mg, 0.2 mmol) prepared by procedure
A. After purification by silica gel column chromatography using nꢀpentane as the eluent, compound 3c
1
was obtained as a white solid (19.9 mg, 58%). H NMR (400 MHz, CDCl3) δ ppm 7.81 (d, J = 8.3 Hz,
13
2H), 7.76 (d, J = 8.3 Hz, 2H). C NMR (100 MHz, CDCl3) δ ppm 134.6 (d, JCꢀF = 33.3 Hz), 132.7,
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126.2 (q, JCꢀF = 3.7 Hz), 123.1 (q, JCꢀF = 273.0 Hz), 117.4, 116.1. 19F NMR (376 MHz, CDCl3) δ ppm ꢀ
1
2
3
63.58 (s, 3F).
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1-(4-(Trifluoromethyl)phenyl)ethan-1-one (3d) Compound 3d was prepared following the general
procedure, starting from 4ꢀacetylbenzenediazonium tetrafluoroborate (46.8 mg, 0.2 mmol) prepared by
procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
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(20/1) as the eluent, compound 3d was obtained as a colorless oil (20.8 mg, 55%). H NMR (400 MHz,
CDCl3) δ ppm 8.13 – 7.99 (m, 2H), 7.81 – 7.65 (m, 2H). 13C NMR (100 MHz, CDCl3) δ ppm 196.9,
19
139.7, 134.5 (q, JCꢀF = 32.4 Hz), 128.6, 125.7 (q, JCꢀF = 3.8 Hz), 123.1 (q, JCꢀF = 272.8 Hz), 26.8. F
NMR (376 MHz, CDCl3) δ ppm ꢀ63.58 (s, 3F).
Phenyl(4-(trifluoromethyl)phenyl)methanone (3e) Compound 3e was prepared following the general
procedure, starting from 4ꢀbenzoylbenzenediazonium tetrafluoroborate (59.2 mg, 0.2 mmol) prepared by
procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
1
(20/1) as the eluent, compound 3e was obtained as a white solid (25.3 mg, 50%). H NMR (400 MHz,
CDCl3) δ ppm 7.90 (d, J = 8.0 Hz, 2H), 7.83 – 7.79 (m, 1H), 7.76 (d, J = 8.1 Hz, 2H), 7.67 – 7.61 (m,
1H), 7.54 – 7.47 (m, 1H). 13C NMR (100 MHz, CDCl3) δ ppm 197.0, 140.8, 136.8, 133.8 (q, JCꢀF = 32.7
Hz), 133.1, 130.1, 130.0, 128.5, 125.4 (q, JCꢀF = 3.8 Hz), 123.7 (q, JCꢀF = 274.1 Hz). 19F NMR (376
MHz, CDCl3) δ ppm ꢀ63.05 (s, 3F).
1-Nitro-4-(trifluoromethyl)benzene (3g) Compound 3g was prepared following the general procedure,
starting from 4ꢀnitrobenzenediazonium tetrafluoroborate (47.4 mg, 0.2 mmol) prepared by procedure B.
After purification by silica gel column chromatography using nꢀhexane/ethyl acetate (50/1) as the eluent,
1
compound 3g was obtained as a colorless oil (19.0 mg, 50%). H NMR (400 MHz, CDCl3) δ ppm 8.36
(d, J = 8.5 Hz, 2H), 7.84 (d, J = 8.5 Hz, 2H). 13C NMR (100 MHz, CDCl3) δ ppm 150.0, 136.1 (q, JCꢀF
=
33.1 Hz), 126.8 (q, JCꢀF = 3.8 Hz), 124.1 123.0 (q, JCꢀF = 272.9 Hz). 19F NMR (376 MHz, CDCl3) δ ppm
ꢀ63.24 (s, 3F).
Ethyl 4-(trifluoromethyl)benzenesulfonate (3r) Compound 3r was prepared following the general
procedure, starting from 4ꢀ(ethoxysulfonyl)benzenediazonium tetrafluoroborate (60.0 mg, 0.2 mmol)
prepared by procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl
1
acetate (20/1) as the eluent, compound 3r was obtained as a colorless oil (20.4 mg, 40%). H NMR (400
MHz, CDCl3) δ ppm 8.08 – 8.01 (m, 2H), 7.83 (d, J = 8.2 Hz, 2H), 4.28 – 4.11 (m, 2H), 1.34 (t, J = 7.1
13
Hz, 3H). C NMR (100 MHz, CDCl3) δ ppm 140.0, 135.4 (q, JCꢀF = 33.3 Hz), 128.4, 126.4 (q, JCꢀF
3.6 Hz), 123.1 (q, JCꢀF = 273.2 Hz), 67.7, 14.8. 19F NMR (376 MHz, CDCl3) δ ppm ꢀ63.33 (s, 3F).
=
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Ethyl 2-(trifluoromethyl)benzoate (3s) Compound 3s was prepared following the general procedure,
starting from 2ꢀ(ethoxycarbonyl)benzenediazonium tetrafluoroborate (52.8 mg, 0.2 mmol) prepared by
procedure B. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
1
2
3
4
5
6
1
(20/1) as the eluent, compound 3s was obtained as a light yellow oil (14.4 mg, 30%). H NMR (400
7
8
9
MHz, CDCl3) δ ppm 7.89 – 7.69 (m, 2H), 7.67 – 7.49 (m, 2H), 4.40 (q, J = 7.1 Hz, 2H), 1.39 (t, J = 7.1
Hz, 3H). 13C NMR (100 MHz, CDCl3) δ ppm 166.9, 131.7, 131.6 (q, JCꢀF = 1.7 Hz), 131.0, 130.1, 128.7
(q, JCꢀF = 32.5 Hz), 126.6 (q, JCꢀF = 5.0 Hz), 123.4 (q, JCꢀF = 273.3 Hz) 62.0, 13.9. 19F NMR (376 MHz,
CDCl3) δ ppm ꢀ59.41 (s, 3F).
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4-(Tert-butyl)-4'-(trifluoromethyl)-1,1'-biphenyl (3t) Compound 3t was prepared following the general
procedure, starting from 4'ꢀ(tertꢀbutyl)ꢀ[1,1'ꢀbiphenyl]ꢀ4ꢀdiazonium tetrafluoroborate (64.8 mg, 0.2
mmol) prepared by procedure B. After purification by silica gel column chromatography using nꢀ
hexane/ethyl acetate (20/1) as the eluent, compound 3t was obtained as a white solid (27.2 mg, 48%). 1H
13
NMR (400 MHz, CDCl3) δ ppm 7.70 (s, 4H), 7.60 – 7.45 (m, 4H), 1.39 (s, 9H). C NMR (100 MHz,
CDCl3) δ ppm 151.4, 144.6, 136.8, 129.0 (q, JCꢀF = 32.3 Hz), 127.2, 126.9, 126.0, 125.6 (q, JCꢀF = 4.1
Hz), 123.0, 34.6, 31.3. 19F NMR (376 MHz, CDCl3) δ ppm ꢀ62.37 (s, 3F).
N-(4-(trifluoromethyl)phenyl)acetamide (3u) Compound 3u was prepared following the general
procedure, starting from 4ꢀacetamidobenzenediazonium tetrafluoroborate (49.8 mg, 0.2 mmol) prepared
by procedure A. After purification by silica gel column chromatography using nꢀhexane/ethyl acetate
1
(5/1) as the eluent, compound 3u was obtained as a white solid (20.3 mg, 55%). H NMR (400 MHz,
13
CDCl3) δ ppm 7.61 (d, J = 8.7 Hz, 2H), 7.56 (d, J = 8.6 Hz, 2H), 7.49 (s, 1H), 2.21 (s, 3H). C NMR
(100 MHz, CDCl3) δ ppm 169.3, 140.6, 126.3 (q, JCꢀF = 3.4 Hz), 124.0 (q, JCꢀF = 271.77 Hz), 119.7,
24.7. 19F NMR (376 MHz, CDCl3) δ ppm ꢀ62.22 (s, 3F).
1-Bromo-3-(trifluoromethyl)benzene (3v) Compound 3v was prepared following the general procedure,
starting from 3ꢀbromobenzenediazonium tetrafluoroborate (54.2 mg, 0.2 mmol) prepared by procedure
B. After purification by silica gel column chromatography using nꢀpentane as the eluent, compound 3v
1
was obtained as a colorless oil (25.8 mg, 58%). H NMR (400 MHz, CDCl3) δ ppm 7.79 (d, J = 2.4 Hz,
13
1H), 7.69 (d, J = 8.1 Hz, 1H), 7.57 (d, J = 7.8 Hz, 2H), 7.36 (t, J = 8.0 Hz, 1H). C NMR (100 MHz,
CDCl3) δ ppm 135.0, 132.5 (q, JCꢀF = 33.0 Hz), 130.4, 128.5 (q, JCꢀF = 3.8 Hz), 123.6 (q, JCꢀF = 3.4 Hz),
123.2 (q, JCꢀF = 272.7 Hz), 122.7. 19F NMR (376 MHz, CDCl3) δ ppm ꢀ62.98 (s, 3F).
1-Bromo-4-(trifluoromethyl)benzene (3w) Compound 3w was prepared following the general
procedure, starting from 4ꢀbromobenzenediazonium tetrafluoroborate (54.2 mg, 0.2 mmol) prepared by
procedure B. After purification by silica gel column chromatography using nꢀpentane as the eluent,
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1
compound 3w was obtained as a colorless oil (28.1 mg, 63%). H NMR (400 MHz, CDCl3) δ ppm 7.61
1
2
3
4
(d, J = 8.3 Hz, 2H), 7.47 (d, J = 8.4 Hz, 2H). 13C NMR (100 MHz, CDCl3) δ ppm 132.1, 129.6 (q, JCꢀF
=
19
33.0 Hz), 126.9 (q, JCꢀF = 3.7 Hz), 126.4 (q, JCꢀF = 1.3 Hz), 123.9 (q, JCꢀF = 272.1 Hz). F NMR (376
5
6
MHz, CDCl3) δ ppm ꢀ62.85 (s, 3F).
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8
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6-(Trifluoromethyl)isobenzofuran-1(3H)-one (3x) Compound 3x was prepared following the general
procedure, starting from 3ꢀoxoꢀ1,3ꢀdihydroisobenzofuranꢀ5ꢀdiazonium tetrafluoroborate (49.6 mg, 0.2
mmol) prepared by procedure A. After purification by silica gel column chromatography using nꢀ
hexane/ethyl acetate (10/1) as the eluent, compound 3x was obtained as a white solid (17.3 mg, 40%).
1H NMR (400 MHz, CDCl3) δ ppm 8.27 – 8.13 (m, 1H), 8.06 – 7.89 (m, 1H), 7.66 (dt, J = 8.0, 0.8 Hz,
1H), 5.40 (s, 2H). 13C NMR (100 MHz, CDCl3) δ ppm 169.5, 149.7, 132.1 (q, JCꢀF = 33.2 Hz), 130.9 (q,
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JCꢀF = 3.3 Hz), 126.7, 123.1 (q, JCꢀF = 3.7 Hz), 123.4 (q, JCꢀF = 272.7 Hz), 123.2, 70.0. F NMR (376
MHz, CDCl3) δ ppm ꢀ62.55 (s, 3F).
Acknowledgment
This work was supported by the National Natural Science Foundation of China (21421002, 21332010,
21272036) and the National Basic Research Program of China (2012CB21600).
Supporting Information Available: Copies of 1H, 19F, and 13C NMR spectra. These material are
available free of charge via the Internet at http://pubs.acs.org.
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