Synthesis of N-aryl trifluoromethylarylketoimines by palladium-catalyzed Suzuki coupling reaction of N-aryltrifluoroacetimidoyl chlorides with aryl boronic acids

Article abstract of DOI:10.1016/j.jfluchem.2010.04.011

A highly efficient Suzuki reaction between N-aryltrifluoroacetimidoyl chlorides and aryl boronic acids using Pd(PPh₃)₄ as a catalyst has been developed. This route allows for selective synthesis of N-aryl trifluoromethylarylketoimines in high yields under mild reaction conditions.

Full text of DOI:10.1016/j.jfluchem.2010.04.011

Journal of Fluorine Chemistry 131 (2010) 856–860
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Synthesis of N-aryl trifluoromethylarylketoimines by palladium-catalyzed
Suzuki coupling reaction of N-aryltrifluoroacetimidoyl chlorides with aryl
boronic acids
*
Chun-Lin Li, Mu-Wang Chen, Xing-Guo Zhang
College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
A R T I C L E I N F O
A B S T R A C T
Article history:
A highly efficient Suzuki reaction between N-aryltrifluoroacetimidoyl chlorides and aryl boronic acids
using Pd(PPh3)4 as a catalyst has been developed. This route allows for selective synthesis of N-aryl
trifluoromethylarylketoimines in high yields under mild reaction conditions.
ß 2010 Elsevier B.V. All rights reserved.
Received 25 March 2010
Received in revised form 30 April 2010
Accepted 30 April 2010
Available online 8 May 2010
Keywords:
Ketoimine
Suzuki reaction
Trifluoroacetimidoyl chlorides
1. Introduction
etoimines [5,7], but aromatic compounds were limited to electron-
rich phenols. Therefore, the discovery of new readily available
Organofluorine compounds have attracted considerable atten-
tion due to their wide range of applications in the pharmaceutical
and agrochemical industries [1]. In particular, trifluoromethyl-
substituted molecules have become a subject of intense investiga-
tions in recent years because of their relevant properties [2].
Trifluoromethyl arylketoimines, a class of versatile building blocks
or precursor products, played an important role in the synthesis of
CF3-containing functional molecules. For example, some fluorinat-
ed indolines could be prepared from trifluoromethyl ketoimines
and 2-p-tolylsulfinylalkylbenzenes by a tandem process [3]. The
CF3-containing chiral amines could also be synthesized from
trifluoromethyl arylketoimines by an asymmetric alkylation
reaction [4]. Fluorinated bis(phenoxyketimine)titanium com-
plexes, the catalysts for polymerization of propylene, were also
prepared from CF3-containing arylketoimines [5]. Usually, tri-
fluoromethyl arylketoimines were synthesized via condensation
reaction of trifluoromethyl ketones with amines under high
temperature conditions [6]. However, some substituted-aryl
trifluoromethylketoimines are unavailable because of the scarcity
of 1-(substituted-aryl)-2,2,2-trifluoroethanones. Friedel–Crafts re-
action of N-aryltrifluoroacetimidoyl chlorides with aromatic
compounds provides another access for trifluoromethyl arylk-
fluorine sources for efficient and concise synthesis route to
trifluoromethyl arylketoimines remains a challenging area for
exploration.
The Suzuki cross-coupling reaction is a powerful and widely
used method for the formation of carbon-carbon bond and for
the synthesis of biaryls and multi-substituted ethylenes [8].
Considerable aryl halides and vinyl halides were coupled with
boronic acids to afford aryl- and vinylarenes, respectively.
However, imidoyl chlorides which bearing a chlorine atom at sp2
carbon, have never been explored for the coupling reaction with
aryl boronic acids. Usually, phosphine or nitrogen ligands were
used to improve the efficiency and to control selectivity of
Suzuki coupling reactions, and much attention has been paid to
design complicated ligands or palladium complexes [9]. Recent-
ly, Sarkar and co-workers described their work in the Suzuki
reactions using Schiff bases as effective ligands [10]. N-
Aryltrifluoroacetimidoyl chlorides [11], bearing Schiff base’s
structure moiety, are versatile intermediates in the synthesis of
CF3-containing compounds [12]. We envisioned whether they
could be used as both ligand and reactant in Suzuki coupling
reactions to provide N-aryl trifluoromethylarylketoimines which
were key materials in our research. Herein, we wish to report a
simple and efficient protocol for the synthesis of trifluoromethyl
arylketoimines by palladium-catalyzed Suzuki coupling reac-
tions of N-aryltrifluoroacetimidoyl chlorides with aryl boronic
acids (Scheme 1).
* Corresponding author. Tel.: +86 577 8668 9615; fax: +86 577 8668 9615.
E-mail address: zxg@wzu.edu.cn (X.-G. Zhang).
0022-1139/$ – see front matter ß 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2010.04.011

C.-L. Li et al. / Journal of Fluorine Chemistry 131 (2010) 856–860
857
Table 2
Palladium-catalyzed Suzuki coupling reaction.a
Scheme 1.
2. Results and discussion
The reaction between N-(4-tolyl)-2,2,2-trifluoroacetimidoyl
chloride (1a) and phenyl boronic acid (2a) in toluene was selected
as a model reaction to optimize the reaction conditions. As shown
in Table 1, various palladium catalysts were firstly tested (entries
1–4). The results indicated that the coupling reaction could be
catalyzed by either Pd(0) or Pd(II) catalyst, and Pd(PPh3)4 provided
the highest yield of target product 3 (87% entry 4). Subsequently, a
series of bases were investigated, the results suggested that bases
have dramatic effects on the yields of cross-coupling product
(entries 4–8). We were delighted to observe the reaction provided
target product 3 in 97% yield in the presence of 3 equiv. of
K3PO4ꢀ3H2O (entry 8). During the examination of solvent (entries
9–11), some polar solvents (such as DMF, THF and dioxane) were
found less effective than toluene. We also observed that the yields
of product 3 decreased obviously when the amount of Pd(PPh3)4
reduced or reaction temperature decreased (entries 12 and 13).
With these promising results in hand, we decided to explore the
scope of the Suzuki coupling reaction. As listed in Table 2, a series
of N-aryltrifluoroacetimidoyl chlorides and aryl boronic acids were
investigated under the optimized conditions. Initially, a series of
aryl boronic acids bearing different substitutes were tested by their
reaction with substrate 1a or 1b (entries 1–8). The results revealed
that both electron-rich and electron-deficient phenyl boronic acids
are suitable substrates for the coupling reaction and provided the
corresponding trifluoromethyl arylketoimines in good to excellent
yields (entries 1–4). The reactions between imidoyl chlorides and
polycyclic or heterocyclic aryl boronic acids also proceeded
smoothly to provide trifluoromethyl arylketoimines in moderate
yields (entries 5–7). Naphthalen-1-yl boronic acid 2f and furan-3-
yl boronic acid 2 g, for instance, underwent the coupling reaction
with substrate 1b successfully to afford the corresponding
Entry 1 Ar=
2 Ar0=
Product Yield
(%)b
1
2
4-CH3–C6H4 (1a)
4-Cl–C6H4 (2b)
4-F–C6H4 (2c)
4
5
91
90
79
81
65
61
57
98
71
90
75
78
74
71
83
73
61
58
95
94
74
86
4-CH3–C6H4 (1a)
4-CH3–C6H4 (1a)
4-CH3–C6H4 (1a)
4-CH3–C6H4 (1a)
4-CH3O–C6H4 (1b)
4-CH3O–C6H4 (1b)
4-CH3O–C6H4 (1b)
C6H5 (1c)
3
3-NO2–C6H4 (2d)
4-CH3O–C6H4 (2e)
naphthalen-1-yl (2f)
naphthalen-1-yl (2f)
furan-3-yl (2g)
C6H5 (2a)
6
4
7
5
8
6
9
7
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
8
9
C6H5 (2a)
10
11
12
13
14
15
16
17
18
19
20
21
22
4-Cl–C6H4 (1d)
C6H5 (2a)
2-NO2–C6H4 (1e)
2-CH3–C6H4 (1f)
4-Cl–C6H4 (1d)
C6H5 (2a)
C6H5 (2a)
2-CH3O–C6H4 (2h)
2-CH3O–C6H4 (2h)
3-NO2–C6H4 (2d)
4-CH3O–C6H4 (2e)
4-CH3–C6H4 (2i)
2-CH3O–C6H4 (2h)
4-Cl–C6H4 (2b)
4-F–C6H4 (2c)
4-CH3–C6H4 (1a)
4-CH3O–C6H4 (1b)
2-CH3–C6H4 (1f)
2-NO2–C6H4 (1e)
2-CH3–C6H4 (1f)
4-CH3O–C6H4 (1b)
4-CH3O–C6H4 (1b)
4-Cl–C6H4 (1d)
4-Cl–C6H4 (2b)
4-CH3O–C6H4 (2e)
4-Cl–C6H4 (1d)
23
C6H5 (2a)
Trace
a
Reaction conditions: 1 (0.5 mmol), 2 (0.6 mmol), Pd(PPh3)4 (5 mol%), K3PO4ꢀ3H2O
(1.5 mmol) in toluene (3 mL) at 100 8C for 8 h.
b
Isolated yield.
ketoimines in 61% and 57% yields, respectively (entries 6 and 7).
Subsequently, various N-aryltrifluoroacetimidoyl chlorides were
evaluated by their reaction with phenyl boronic acid 2a (entries 8–
12). The results demonstrated that the reaction was well-tolerated
to a range of imidoyl chlorides with different substitutes attaching
to benzene ring, such as 4-methoxy, 4-chloro, 2-methyl and 2-
nitro. In the further exploration of the scope of N-aryltrifluor-
oacetimidoyl chlorides and aryl boronic acids (entries 13–22), we
found that the steric effect affected the reaction to some extent. For
example, the reaction between N-(2-tol)trifluoroacetimidoyl
chloride (1f) and 2-methoxyphenyl boronic acid (2h) provided
desired product in a low yield (58%, entry 18). It is worth noting
that the strong electron-withdrawing ability of trifluoromethyl
group is essential to this Suzuki coupling reaction. Without the
activation of C–Cl bond by trifluoromethyl, the coupling reaction
did not work. For example, only trace amount of the desired
product could be obtained when N-(4-tol)acetimidoyl chloride was
treated with phenyl boronic acid (2a) under the standard
conditions (entry 23).
Table 1
Optimization of reaction conditions.a
Entry
[Pd] (mol%)
Solvent
Base
T (8C)
Yield
(%)b
1
2
PdCl2 (5)
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
1,4-dioxane
DMF
Cs2CO3
100
100
100
100
100
100
100
100
100
100
100
100
80
59
73
65
87
84
37
79
97
45
8
Pd(OAc)2 (5)
Pd2(dba)3 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (2)
Pd(PPh3)4 (5)
Cs2CO3
3
Cs2CO3
4
Cs2CO3
5
NaOH
3. Conclusion
6
Et3N
7
K2CO3
8
K3PO4ꢀ3H2O
K3PO4ꢀ3H2O
K3PO4ꢀ3H2O
K3PO4ꢀ3H2O
K3PO4ꢀ3H2O
K3PO4ꢀ3H2O
In summary, we have developed a practical palladium-catalyzed
coupling method for the synthesis of N-aryl trifluoromethylarylk-
etoimines. In the presence of Pd(PPh3)4 and K3PO4ꢀ3H2O, a variety of
N-aryltrifluoroacetimidoyl chlorides underwent the palladium-
catalyzed Suzuki coupling reactions with various aryl boronic acids
successfully to afford the corresponding N-aryl trifluoromethylar-
ylketoimines in moderate to excellent yields. Work to extend the
application of N-aryl trifluoromethylarylketoimines in organic
9
10
11
12
13
THF
64
85
88
Toluene
Toluene
a
Reaction conditions: 1a (0.5 mmol), phenyl boronic (0.6 mmol), base (1.5 mmol),
solvent (3 mL) at 100 8C for 8 h.
b
Isolated yield.

858
C.-L. Li et al. / Journal of Fluorine Chemistry 131 (2010) 856–860
synthesis is currently underway. For example, these coupling
productsarebeingused inasymmetricreduction reactiontoprepare
CF3-containing chiral secondary amines.
143.5, 148.1, 153.9 (JC–F = 33.6 Hz); 19F NMR (282.2 MHz, CDCl3)
d:
ꢁ69.92; MS (ESI): m/z = 309 (M+H+); HRMS (EI) calcd. for
C15H11F3N2O2 (M+) 308.0767, found 308.0768.
+
4.1.5. 4-Methyl-N-(2,2,2-trifluoro-1-(4-
4. Experimental
methoxyphenyl)ethylidene)benzenamine 7
Chemicals were either purchased or purified by standard
techniques. 1H NMR and 13C NMR spectra were measured on a 300
or 500 MHz spectrometer (1H: 300 MHz, 13C: 75 or 125 MHz, 19F:
282.2 MHz), using CDCl3 as the solvent with tetramethylsilane
(TMS) as an internal standard at room temperature. Chemical
Pale yellow oil. IR (thin film): 3017, 1663, 1251, 1213, 1188,
1128 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
: 2.27 (s, 3H), 3.78 (s, 3H),
6.68 (d, J = 8.2 Hz, 2H), 6.80 (d, J = 8.8 Hz, 2H), 7.02 (d, J = 8.2 Hz,
2H), 7.19 (d, J = 8.8 Hz, 2H); 13C NMR (75 MHz, CDCl3)
: 20.8, 55.2,
120.1 (JC–F = 277.4 Hz), 120.7, 127.7, 128.7, 129.2, 130.5, 134.9,
d
shifts are given in
d
relative to TMS, the coupling constants J are
144.9, 155.8 (JC–F = 33.0 Hz), 160.8; 19F NMR (282.2 MHz, CDCl3)
d:
given in Hz. All reactions under nitrogen atmosphere were
conducted using standard Schlenk techniques. Column chroma-
tography was performed using EM Silica gel 60 (300–400 mesh).
ꢁ69.87; MS (ESI): m/z = 294 (M+H+); HRMS (EI) calcd. for
C
16H14F3NO+ (M+) 293.1022, found 293.1024.
4.1.6. 4-Methyl-N-(2,2,2-trifluoro-1-(naphthalen-1-
yl)ethylidene)benzenamine 8
4.1. General procedure for synthesis of N-aryl
trifluoromethylarylketoimines
Pale yellow oil. IR (thin film): 1506, 1319, 1212, 1187, 1134,
777 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 2.08 (s, 3H), 6.68 (d,
J = 8.2 Hz, 2H), 6.79 (d, J = 8.2 Hz, 2H), 7.42–7.45 (m, 4H), 7.60–7.62
(m, 1H), 7.71–7.87 (m. 2H); 13C NMR (125 MHz, CDCl3)
: 20.8,
A mixture of N-aryltrifluoroacetimidoyl chlorides (0.5 mmol),
aryl boronic acids (0.6 mmol), Pd(PPh3)4 (2.9 mg, 0.025 mmol) and
K3PO4ꢀ3H2O (399 mg, 1.5 mmol) in 3 mL toluene was stirred at
100 8C for 8 h. The reaction was monitored by TLC and GC analysis.
After the reaction was finished, the solvent was evaporated under
reduced pressure. Purification of the residue and elution with 25:1
petroleum ether/ethyl acetate give the products 3–25.
d
120.1 (JC–F = 277.5 Hz), 120.8, 123.4, 124.7, 124.9, 126.5, 127.1,
127.2, 128.5, 129.1, 129.9, 130.4, 133.2, 135.9, 144.1, 156.5 (JC–
F = 33.8 Hz); 19F NMR (282.2 MHz, CDCl3)
d
: ꢁ69.84; MS (ESI): m/
z = 314 (M+H+); HRMS (EI) calcd. for C19H14F3N+ (M+) 313.1073,
found 313.1076.
4.1.1. 4-Methyl-N-(2,2,2-trifluoro-1-phenylethylidene)benzenamine
4.1.7. 4-Methoxy-N-(2,2,2-trifluoro-1-(naphthalen-1-
yl)ethylidene)benzenamine 9
3
Pale yellow oil. IR (thin film): 3020, 1667, 1198, 1130, 970,
Pale yellow oil. IR (thin film): 1601, 1505, 1251, 1212, 1186,
698 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 2.24 (s, 3H), 6.65 (d,
J = 8.2 Hz, 2H), 6.98 (d, J = 8.2 Hz, 2H), 7.20–7.38 (m, 5H); 13C NMR
(75 MHz, CDCl3) : 20.9, 119.9 (JC–F = 277.4 Hz), 121.0, 128.6,
1131, 778 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
: 2.58 (s, 3H), 6.52 (d,
J = 6.8 Hz, 2H), 6.78 (d, J = 6.8 Hz, 2H), 7.42–7.47 (m, 4H), 7.58–7.61
(m, 1H), 7.80–7.90 (m, 2H); 13C NMR (125 MHz, CDCl3)
d:
d
129.4, 130.1, 130.3, 132.4, 135.3, 144.3, 156.4 (JC–F = 33.4 Hz); 19
F
55.1,113.7, 120.3 (JC–F = 277.5 Hz), 123.7, 124.8, 125.0, 126.6,
127.1, 127.3, 128.6, 129.5, 129.8, 130.4, 133.3,139.3, 154.7 (JC–
NMR (282.2 MHz, CDCl3)
d
: ꢁ69.86; MS (ESI): m/z = 264 (M+H+);
HRMS (EI) calcd. for C15H12F3N+ (M+) 263.0916, found 263.0919.
F = 33.8 Hz), 158.3; 19F NMR (282.2 MHz, CDCl3)
d
: ꢁ69.84; MS
(ESI): m/z = 330 (M+H+); HRMS (EI) calcd. for C19H14F3NO+ (M+)
4.1.2. N-(1-(4-Chlorophenyl)-2,2,2-trifluoroethylidene)-4-
methylbenzenamine 4
329.1022, found 329.1026.
Pale yellow oil. IR (thin film): 3022, 1668, 1191, 1129, 1093,
4.1.8. 4-Methoxy-N-(2,2,2-trifluoro-1-(furan-3-
yl)ethylidene)benzenamine 10
968 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 2.27 (s, 3H), 6.65 (d,
J = 8.2 Hz, 2H), 7.02 (d, J = 8.2 Hz, 2H), 7.17 (d, J = 8.4 Hz, 2H), 7.43
(d, J = 8.4 Hz, 2H); 13C NMR (75 MHz, CDCl3)
: 20.9, 119.8 (JC–
F = 277.4 Hz), 121.6, 127.0, 128.5, 129.3, 130.1, 134.2, 136.5, 144.1,
Pale yellow oil. IR (thin film): 1653, 1505, 1244, 1211, 1185,
d
1166, 1132, 740 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 3.82 (s, 3H),
5.97 (s, 1H), 6.77–6.81 (m, 2H), 6.87–6.92 (m, 2H), 7.26–7.27 (m,
1H), 7.56 (m, 1H); 13C NMR (125 MHz, CDCl3)
: 55.4, 109.8, 113.9,
115.2, 119.9 (JC–F = 276.3 Hz), 120.0, 141.6, 142.8, 146.3, 148.6 (JC–
155.1 (JC–F = 33.8 Hz); 19F NMR (282.2 MHz, CDCl3)
(ESI): m/z = 298 (M+H+); HRMS (EI) calcd. for C15H11ClF3N+ (M+)
d
: ꢁ69.87; MS
d
297.0527, found 297.0528.
F = 33.8), 157.4; 19F NMR (282.2 MHz, CDCl3)
m/z = 270 (M+H+); HRMS (EI) calcd. for C13H10F3NO2 (M+)
d
: ꢁ69.84; MS (ESI):
+
4.1.3. 4-Methyl-N-(2,2,2-trifluoro-1-(4-
269.0658, found 269.0659.
fluorophenyl)ethylidene)benzenamine 5
Pale yellow oil. IR (thin film): 3017, 1670, 1192, 1128, 1058,
4.1.9. 4-Methoxy-N-(2,2,2-trifluoro-1-
966 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 2.27 (s, 3H), 6.66 (d,
J = 8.2 Hz, 2H), 6.98–7.03 (m, 4H), 7.20–7.26 (m, 2H); 13C NMR
(75 MHz, CDCl3) : 20.8, 119.8 (JC–F = 277.5 Hz), 120.8, 128.2,
129.0, 129.5, 130.9,131.0, 144.2, 155.3 (JC–F = 33.8 Hz), 163.4 (JC–
phenylethylidene)benzenamine 11
Ref. [6a], Pale yellow oil. Yield IR (thin film): 1668, 1506, 1250,
d
1211, 1197,1129, 780 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 3.74 (s,
3H), 6.74–6.78 (m, 4H), 7.24–7.27 (m, 2H), 7.32–7.39 (m, 3H); 13
NMR (75 MHz, CDCl3) : 55.2, 118.2, 120.0 (JC–F = 276.8 Hz), 133.3,
C
F = 250.1 Hz); 19F NMR (282.2 MHz, CDCl3)
ꢁ109.05 (s, 1F); MS (ESI): m/z = 282 (M+H+); HRMS (EI) calcd. for
d
: ꢁ69.89 (s, 3F),
d
128.6, 130.1, 130.7, 138.1, 139.7, 155.4 (JC–F = 33.0 Hz), 157.8; 19
F
C
15H11F4N+ (M+) 281.0822, found 281.0826.
NMR (282.2 MHz, CDCl3)
d
: ꢁ69.86; MS (ESI): m/z = 280 (M+H+).
4.1.4. 4-Methyl-N-(2,2,2-trifluoro-1-(3-
4.1.10. N-(2,2,2-Trifluoro-1-phenylethylidene)benzenamine 12
Ref. [6a], Pale yellow oil. IR (thin film): 2916, 1669, 1196, 1133,
971, 698 cmꢁ1 1H NMR (300 MHz, CDCl3)
: 6.73–6.76 (m, 2H),
7.02–7.06 (m, 1H), 7.17–7.22 (m, 3H), 7.25–7.35 (m, 4H); 13C NMR
(125 MHz, CDCl3) :119.8 (JC–F = 277.5 Hz), 120.5, 125.3, 128.5,
nitrophenyl)ethylidene)benzenamine 6
Pale yellow oil. IR (thin film): 3018, 1669, 1519, 1351, 1193,
;
d
1129, 968 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
: 2.25 (s, 3H), 6.62 (d,
J = 8.2 Hz, 2H), 7.01 (d, J = 8.2 Hz, 2H), 7.52 (m, 2H), 8.12 (s, 1H),
8.21–8.25 (m, 1H). 13C NMR (75 MHz, CDCl3)
: 20.8, 118.5 (JC–
F = 276.8 Hz), 120.5 120.7, 123.8, 129.7, 129.9, 131.8, 134.6, 136.2,
d
d
128.7, 128.8, 130.0, 130.2, 147.1, 157.0 (JC–F = 33.8); 19F NMR
(282.2 MHz, CDCl3)
d
: ꢁ69.84; MS (ESI): m/z = 250 (M+H+).

C.-L. Li et al. / Journal of Fluorine Chemistry 131 (2010) 856–860
859
4.1.11. 4-Chloro-N-(2,2,2-trifluoro-1-phenylethylidene)benzenamine
3H), 6.49 (m, 1H), 6.78 (d, J = 8.8 Hz, 2H), 7.00–7.02 (m, 2H), 7.16–
7.21 (m, 3H); 13C NMR (75 MHz, CDCl3)
: 17.6, 55.1, 118.4, 120.1
(JC–F = 278.3 Hz), 122.0, 124.8, 126.2, 127.7, 128.0, 130.2, 130.5,
13
d
Ref. [6a], Pale yellow oil. IR (thin film): 3080. 1667, 1191, 1128,
1090, 768 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 6.67 (d, J = 8.4 Hz,
2H), 7.13–7.21 (m, 4H), 7.31–7.35 (m, 3H); 13C NMR (75 MHz,
CDCl3) : 119.8 (JC–F = 277.5 Hz), 122.1, 125.3, 128.7, 129.1, 130.2,
146.6, 156.0 (JC–F = 33.0 Hz), 161.0; 19F NMR (282.2 MHz, CDCl3)
d:
ꢁ69.85; MS (ESI): m/z = 294 (M+H+); HRMS (EI) calcd. for
d
C
16H14F3NO+ (M+) 293.1022, found 293.1024.
131.0, 137.1, 145.6, 157.7 (JC–F = 33.9 Hz); 19F NMR (282.2 MHz,
CDCl3)
d
: ꢁ69.93; MS (ESI): m/z = 284 (M+H+).
4.1.18. 2-Nitro-N-(2,2,2-trifluoro-1-p-tolylethylidene)benzenamine
20
4.1.12. 2-Nitro-N-(2,2,2-trifluoro-1-phenylethylidene)benzenamine
Pale yellow oil. IR (thin film): 3019, 1670, 1518, 1350, 1194,
14
1128, 763 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
: 2.22 (s, 3H), 6.61 (d,
J = 8.9 Hz, 1H), 6.92–7.00 (m, 2H), 7.13–7.16 (m, 1H), 7.20–7.22 (m,
2H), 7.29–7.35 (m, 2H); 13C NMR (75 MHz, CDCl3)
: 17.8, 118.5,
Ref. [13], Pale yellow oil. IR (thin film): 1670, 1521, 1352, 1194,
1129, 753 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 6.02 (d, J = 8.3 Hz,
1H), 7.16–7.22 (m, 1H), 7.35–7.45 (m, 6H), 8.08 (d, J = 8.3 Hz, 1H);
13C NMR (75 MHz, CDCl3)
: 119.3 (JC–F = 278.9 Hz), 120.5, 125.0,
d
119.8 (JC–F = 277.5 Hz), 125.1, 126.1, 128.2, 128.4, 128.5, 130.1,
130.3, 130.4, 146.1, 156.5 (JC–F = 33.8 Hz); 19F NMR (282.2 MHz,
d
125.2, 128.1, 128.7, 129.4, 129.8, 130.1, 131.1, 143.1, 156.9 (JC–
CDCl3)
d
: ꢁ69.92; MS (ESI): m/z = 309 (M+H+); HRMS (EI) calcd. for
F = 33.6 Hz); 19F NMR (282.2 MHz, CDCl3):
z = 295 (M+H+).
d
: ꢁ69.95; MS (ESI): m/
C15H11F3N2O2 (M+) 308.0767, found 308.0768.
+
4.1.19. 2-Methyl-N-(2,2,2-trifluoro-1-(2-
4.1.13. 2-Methyl-N-(2,2,2-trifluoro-1-
methoxyphenyl)ethylidene)benzenamine 21
phenylethylidene)benzenamine 15
Pale yellow oil. IR (thin film): 3020, 1665, 1250, 1196,
Ref. [6a], Pale yellow oil. IR (thin film): 3032, 1666, 1197, 1128,
746 cmꢁ1 1H NMR (300 MHz, CDCl3)
: 2.25 (s, 3H), 6.43 (d,
J = 8.7 Hz, 1H), 6.97 (m, 2H), 7.15–7.17 (m, 1H), 7.22–7.36 (m, 5H);
13C NMR (75 MHz, CDCl3)
: 17.7, 118.5, 119.9 (JC–F = 277.5 Hz),
1127,1042, 756 cmꢁ1 1H NMR (300 MHz, CDCl3)
; d: 2.27 (s, 3H),
;
d
3.61 (s, 3H), 6.38 (d, J = 7.7 Hz, 1H), 6.77 (d, J = 8.3 Hz, 1H), 6.83–
6.95 (m, 3H), 7.12 (m, 2H), 7.26–7.33 (m, 1H); 13C NMR (75 MHz,
d
CDCl3)
d: 17.6, 55.2, 114.0 (JC–F = 277.8 Hz), 117.4, 118.0, 119.9,
125.1, 126.1, 127.2, 128.2, 128.5, 128.8, 130.3, 130.4, 146.1, 156.6
120.4, 125.2, 125.5, 129.0, 129.3, 130.0, 131.6, 146.5, 156.6 (JC–
(JC–F = 33.2 Hz); 19F NMR (282.2 MHz, CDCl3)
m/z = 264 (M+H+).
d
: ꢁ69.82; MS (ESI):
F = 33.0 Hz), 164.5; 19F NMR (282.2 MHz, CDCl3)
d
: ꢁ69.84; MS
(ESI): m/z = 294 (M+H+); HRMS (EI) calcd. for C16H14F3NO+ (M+)
293.1022, found 293.1024.
4.1.14. 4-Chloro-N-(2,2,2-trifluoro-1-(2-
methoxyphenyl)ethylidene)benzenamine 16
4.1.20. N-(1-(4-Chlorophenyl)-2,2,2-trifluoroethylidene)-4-
methoxybenzenamine 22
IR (thin film): 1667, 1252, 1190, 1127, 1094, 1042, 748 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
J = 9.0 Hz, 1H), 6.86–6.91 (m, 1H), 7.08–7.12 (m, 3H), 7.28–7.31 (m,
1H). 13C NMR (75 MHz, CDCl3)
: 55.3, 119.6 (JC–F = 277.5 Hz),
120.6, 121.3, 128.5, 128.7, 129.2, 130.8, 132.0, 133.6, 146.2, 156.6,
d
: 3.60 (s, 3H), 6.67–6.70 (m, 2H), 6.78(d,
Ref. [14], Pale yellow oil. IR (thin film): 3079. 1665, 1250, 1192,
1128, 1093, 1042, 848 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
: 3.76 (s,
3H), 6.75–6.79 (m, 4H), 7.19 (d, J = 8.4 Hz, 2H), 7.32–7.34 (m, 2H);
13C NMR (75 MHz, CDCl3)
: 55.3, 119.9 (JC–F = 277.1 Hz), 123.2,
d
d
156.8 (JC–F = 34.8 Hz); 19F NMR (282.2 MHz, CDCl3)
d
: ꢁ69.85. MS
128.9, 129.3, 129.6, 130.1, 136.4, 139.4, 153.9 (JC–F = 33.2 Hz),
(ESI): m/z = 314 (M+H+); HRMS (EI) calcd. for C15H11ClF3NO+ (M+)
158.0; 19F NMR (282.2 MHz, CDCl3)
(M+H+).
d
: ꢁ69.90; MS (ESI): m/z = 314
313.0476, found 313.0478.
4.1.15. 4-Methyl-N-(2,2,2-trifluoro-1-(2-
4.1.21. 4-Methoxy-N-(2,2,2-trifluoro-1-(4-
methoxyphenyl)ethylidene)benzenamine 17
fluorophenyl)ethylidene)benzenamine 23
Pale yellow solid IR (thin film): 3020, 1665, 1251, 1211, 1195,
Pale yellow oil. IR (thin film): 1669, 1253,1194, 1128, 1042,
1126,1043, 852 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 2.20 (s, 3H),
3.62 (s, 3H), 6.67 (d, J = 8.2 Hz, 2H), 6.90–6.95 (m, 2H), 7.08–7.10
(m, 1H), 7.28–7.32 (m, 3H); 13C NMR (75 MHz, CDCl3)
: 20.9, 55.4,
846 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
: 3.74 (s, 3H), 6.74–6.77 (m,
4H), 7.00–7.05 (m, 2H), 7.22–7.26 (m, 2H); 13C NMR (75 MHz,
CDCl3) : 55.2, 119.9 (JC–F = 277.5 Hz), 123.2, 126.5, 130.8, 131.0,
133.0, 139.5, 154.3, (JC–F = 33.8 Hz), 155.0, 163.4 (JC–F = 250.5 Hz);
d
d
119.8 (JC–F = 277.4 Hz), 120.5, 128.5, 128.7, 129.0, 129.4, 129.9,
130.2, 135.2, 145.0, 155.6 (JC–F = 34.5 Hz), 156.8; 19F NMR
19F NMR (282.2 MHz, CDCl3)
d
: ꢁ69.91(s, 3F), ꢁ109.04 (s, 1F); MS
(282.2 MHz, CDCl3)
d
: ꢁ69.83; MS (ESI): m/z = 294 (M+H+); HRMS
(ESI): m/z = 298 (M+H+); HRMS (EI) calcd. for C15H11F4NO+ (M+)
(EI) calcd. for C16H14F3NO+ (M+) 293.1022, found 293.1024.
297.0771, found 297.0774.
4.1.16. 4-Methoxy-N-(2,2,2-trifluoro-1-(3-
4.1.22. 4-Chloro-N-(1-(4-chlorophenyl)-2,2,2-
trifluoroethylidene)benzenamine 24
nitrophenyl)ethylidene)benzenamine 18
Pale yellow oil. 1670, 1521, 1352, 1252,1196, 1128, 1042,
Pale yellow oil. IR (thin film): 3081, 1668, 1193, 1128, 1092,
873 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
: 3.75 (s, 3H), 6.70–6.75 (m,
4H), 7.52–7.55 (m, 2H), 8.23–8.27 (m, 2H); 13C NMR (75 MHz,
CDCl3) : 55.3, 119.6 (JC–F = 276.8 Hz), 123.2, 123.8, 125.0, 125.2,
848 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 6.67–6.71 (m, 2H), 7.14–
7.22 (m, 4H), 7.29–7.34 (m, 2H); 13C NMR (75 MHz, CDCl3)
: 119.6
(JC–F = 277.7 Hz), 121.9, 125.1, 128.7, 129.2, 130.0, 131.3, 136.9,
d
d
130.0, 132.2, 134.6, 138.7, 148.3, 152.4 (JC–F = 34.5 Hz), 158.3; 19
F
145.2, 156.4 (JC–F = 34.2 Hz); 19F NMR (282.2 MHz, CDCl3)
d:
NMR (282.2 MHz, CDCl3)
HRMS (EI) calcd. for
324.0717.
d
C
: ꢁ69.93; MS (ESI): m/z = 325 (M+H+);
ꢁ69.93; MS (ESI): m/z = 318 (M+H+); HRMS (EI) calcd. for
15H11F3N2O3 (M+) 324.0716, found
C
14H8ClF3N+ (M+) 316.9980, found 316.9982.
+
4.1.23. 4-Chloro-N-(2,2,2-trifluoro-1-(4-
4.1.17. 2-Methyl-N-(2,2,2-trifluoro-1-(4-
methoxyphenyl)ethylidene)benzenamine 25
methoxyphenyl)ethylidene)benzenamine 19
Pale yellow oil. IR (thin film): 1664, 1250, 1211, 1196, 1127,
1041, 846 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d: 2.21 (s, 3H), 3.76 (s,
Pale yellow solid. IR (thin film): 3080, 1666, 1251, 1189, 1128,
1093, 1042, 846 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
: 3.80 (s, 3H),
6.67 (d, J = 8.6 Hz, 2H), 6.78 (d, J = 8.6 Hz, 2H), 7.12–7.18 (m, 4H);

860
C.-L. Li et al. / Journal of Fluorine Chemistry 131 (2010) 856–860
[5] J.B. Edson, Z. Wang, E.J. Kramer, G.W. Coates, J. Am. Chem. Soc. 130 (2008) 4968–
13C NMR (75 MHz, CDCl3)
d
: 55.2, 119.9 (JC–F = 277.5 Hz), 121.9,
4977.
127.7, 129.1, 130.5, 130.6, 133.4, 146.0, 157.3 (JC–F = 33.5 Hz),
[6] (a) M. Abid, M. Savolainen, S. Landge, J. Hu, G.K.S. Prakash, G.A. Olah, B. Torok, J.
Fluorine Chem. 128 (2007) 587–594;
161.1; 19F NMR (282.2 MHz, CDCl3)
d
: ꢁ69.88; MS (ESI): m/z = 314
(M+H+); HRMS (EI) calcd. for C15H11ClF3NO+ (M+) 313.0476, found
313.0478.
(b) A.S. Kiselyov, Tetrahedron Lett. 40 (1999) 4119–4122;
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(a) N. Miyaura, in: F. Diederich, A. de Meijere (Eds.), Metal-Catalyzed Cross-
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We thank the National Natural Science Foundation of China (No.
20872112) and Zhejiang Provincial Natural Science Foundation of
China (Nos. Y407116 and Y4080169) for financial support.
(a) D.J.M. Snelders, G. van Koten, R.J.M.K. Gebbink, J. Am. Chem. Soc. 131 (2009)
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