Nickel-catalyzed C-F bond activation and alkylation of polyfluoroaryl imines

Article abstract of DOI:10.1016/j.jorganchem.2012.10.013

In this paper we show the C-F bond activation and alkylation in polyfluoroaryl imines. An active trimethylphosphine supported nickel-catalyzed cross-coupling reaction of polyfluoroaryl imines with ZnMe₂ under mild conditions is described. According to the in situ ¹⁹F NMR spectroscopic data, the substrates are quantitatively converted into di-methylation products, while mono-methylation can also be realized under the controlled conditions in moderate yields. Apart from ZnMe₂, other organozinc regents were tried in this system. However, due to the nucleophilicity and steric hindrance, they show much lower reactivity than ZnMe₂. Only in the case of benzylic zinc chloride, the dibenzylation product can be obtained quantitatively by raising temperature to 90 °C. The results reported here will benefit the development of C-F bond activation as well as the diversity of Schiff bases.

Full text of DOI:10.1016/j.jorganchem.2012.10.013

Journal of Organometallic Chemistry 723 (2013) 36e42
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Nickel-catalyzed CeF bond activation and alkylation of polyfluoroaryl imines
*
Xiuxiu Yang, Hongjian Sun, Shumiao Zhang, Xiaoyan Li
School of Chemistry and Chemical Engineering, Shandong University, Shanda Nanlu 27, 250100 Jinan, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
In this paper we show the CeF bond activation and alkylation in polyfluoroaryl imines. An active tri-
methylphosphine supported nickel-catalyzed cross-coupling reaction of polyfluoroaryl imines with
ZnMe2 under mild conditions is described. According to the in situ 19F NMR spectroscopic data, the
substrates are quantitatively converted into di-methylation products, while mono-methylation can also
be realized under the controlled conditions in moderate yields. Apart from ZnMe2, other organozinc
regents were tried in this system. However, due to the nucleophilicity and steric hindrance, they show
much lower reactivity than ZnMe2. Only in the case of benzylic zinc chloride, the dibenzylation product
can be obtained quantitatively by raising temperature to 90 ꢀC. The results reported here will benefit the
development of CeF bond activation as well as the diversity of Schiff bases.
Received 7 August 2012
Received in revised form
3 October 2012
Accepted 4 October 2012
Keywords:
CeF activation
Polyfluoroaryl imines
Trimethylphosphine
Methylation
Ó 2012 Elsevier B.V. All rights reserved.
Nickel complex
1. Introduction
Puddephatt and co-workers published the activation of CeF
bond in polyfluoroaryl imines with Pt2Me4(
m-SMe2)2 in 1992 [13].
CeF bond is one of the strongest single bonds in organic
compounds. Because of the chemical and kinetic inertness of
fluorinated compounds caused by the small size and high electro-
negativity of fluorine atom, fluorinated compounds are of current
interest as valuable pharmaceuticals, agrochemicals, polymers and
some other advanced materials [1]. As a result, there has been
increasing interest in the synthesis of selectively substituted fluo-
rocarbons through the activation of CeF bonds with commercially
available polyfluoroarenes or perfluoroarenes [2e6]. This is not
only a way to higher-value fluorinated compounds but also
meaningful to the degradation of fluorinated inert substances.
Transition-metal catalyzed CeF bond activation and function-
alization have attracted much interest [7e58] including stoichio-
metric reactions [7e28,37] hydrodefluorination [29e36] and
catalytic cross-coupling reactions via CeF bond activation [28,40e
58]. Among cross-coupling reactions, nickel is the base-metal that
shows great potential in CeF bond activation [28,37,42e
46,49,54,55]. Therefore, the catalytic conversion of CeF bond into
CeC bond by nickel complexes is of great importance. In addition,
Schiff bases as well as their metal complexes have been found
useful in various fields, e.g., catalysts, biological activity, analysis,
corrosion. The diversification of Schiff bases especially the fluori-
nated Schiff bases is of great significance [59].
The reaction turned out to be a catalytic cycle by Love with the
introduction of ZnMe2 as the methylation agent in 2007 [47].
Dankwardt reported the palladium and nickel catalyzed cross-
coupling of aryl Grignard reagents with aryl fluorides in
moderate to excellent yields of the corresponding unsymmetrical
biaryls [60]. We chose the trimethylphosphine supported nickel
complexes (Ni(PMe3)4 and Ni(PMe3)3Me2) as catalysts to explore
the C,C-cross-coupling reaction via CeF bond activation. The nickel
complexes are very active not only to the perfluorinated phenyl
imines but also the 2,6-difluorinated phenyl imines in the meth-
ylation reaction with dimethyl zinc via CeF bond activation. In
addition, this catalytic system has very good selectivity between
mono-methylation and di-functionalization under the controlled
experimental conditions.
2. Results and discussion
Table 1 shows the results of the catalytic methylation of (2,6-
difluorobenzylidene)-(2,6-diisopropylphenyl)amine (7a) with
nickel complexes supported by different phosphine ligands. The
supporting ligands are trimethylphosphine (PMe3) and n-butyl-
di(adamantyl)phosphine (Ad2P(n-Bu)). The precursors of nickel
include NiCl2, Ni(PMe3)2Cl2, Ni(COD)2 (COD: 1,5-cyclooctadiene).
Comparing the results of entries 2 and 3; entries 5 and 6, it is
concluded that PMe3 is the better supporting ligand than Ad2P(n-
Bu). From the results of entries 2 and 4 it can be drawn that the
complex Ni(PMe3)2Cl2 is a better pre-catalyst than NiCl2 with PMe3
* Corresponding author. Tel.: þ86 531 88361350; fax: þ86 531 88564464.
E-mail address: xli63@sdu.edu.cn (X. Li).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.10.013

X. Yang et al. / Journal of Organometallic Chemistry 723 (2013) 36e42
37
Table 1
Ni-catalyzed methylation of polyfluoroaryl imines via CeF activation.
Entry
Catalyst (10 mol %)
Conversion (%)
Monomethylated yield (%)b
Dimethylated yield (%)b
Ligand (mol %)
1
2
None
NiCl2
0
39.8
0
40
0
0
None
PMe3
(40)
3
NiCl2
0
100
90
0
72
80
0
0
28
10
0
Ad2P(n-Bu)
(40)
PMe3
(10)
PMe3
(40)
Ad2P(n-Bu)
(40)
4a
5
Ni(PMe3)2Cl2
Ni(COD)2
Ni(COD)2
6
0
a
n ¼ 1.7.
b
Yield based on in situ 19F NMR spectra, and yields are average of 2 times.
as supporting ligands. The combination of Ni(COD)2 with PMe3
(entry 5) has better mono-methylation yield (89%) and selectivity
(80%) than those (yield: 72% and selectivity: 72%) of the combina-
tion of Ni(PMe3)2Cl2 and PMe3 (entry 4). The results in Table 1
indicate that dimethylation is also possible for the difluorinated
phenyl imine (entries 4 and 5). The dimethylated products should
be formed from the mono-methylated intermediates.
(perfluorobenzylidene)benzenamine (3a) as substrate no satisfied
yield (only 10%) for the mono-methylated product (3c) could be
reached (Table 3, entry 3).
For this result there is no reasonable explanation. It is not
understandable that the low yield of this mono-methylation is
relevant to the steric effect of the two isopropyl groups on the
phenyl ring because quantitative dimethylation products were
obtained under the experimental conditions (Table 2, entry 3).
To explore the catalytic conditions some salts (LiBr, NaBr, KBr,
NaCl, NH4Cl, KCl and MnCl2) were tried as additives. No improve-
ments were observed. Further catalytic experiments in different
solvents, such as pentane, diethyl ether, THF, CH3CN did not
improve the yields of mono-methylation.
Compared with the work by Love [47], this research has several
advantages. At first, the nickel complexes as catalysts are cheaper
and easier to prepare. Secondly, the nickel complexes as catalysts
are more active than platinum complexes. This nickel catalytic
system can provide the dimethylation products under controlled
conditions while the Love’s platinum catalytic system gives rise to
mono-methylation products. As far as we know, this is the first time
that CeF bond in 2,6-difluorophenyl imines are activated affording
mono-/di-methylated products (ref. [47]: yield < 10% for mono-
methylation and no dimethylation products) and the dimethyla-
tion is quantitative under the controlled conditions. In the same
manner the catalytic system has ortho-selectivity for both mono-
methylation and dimethylation. It has been found that dimethyl
zinc is a good methylation agent for this catalytic system under
mild conditions. This new catalytic system will be useful in nickel-
catalyzed C,C-coupling reactions involving CeF bond activation to
afford new aryl fluorides.
Table
2 describes the main catalytic results with poly-
fluorophenylmethyleneamines as the substrates. In all reactions the
2,6-difluorogroups werequantitativelydimethylatedin theyields of
100%. For the first five entries (entries 1e5) with the perfluorinated
phenyl imines as the substrates the yields are quantitative. It is
understandable that CeF bond cleavage of the perfluorinated aryl
group is much easier than that of a partly fluorinated aryl ring. In
addition, no mono-methylated intermediates could be isolated with
the ratio of substrate:ZnMe2 of 1:1.2. The experiments show there is
no obvious difference in the catalytic activity between Ni(P-
Me3)3Me2 and Ni(PMe3)4. From the difluorinated phenyl imines
(Table 2, entries 6 and 7) a quantitative transformation can also be
completed with the prolonged reaction time up to 20 h. Based on the
experimental results in Table 2, we know that all of the CeF bond
activation and methylation occur at the ortho-positions of the imine
functional group. This implies that the imine is a directing group
because of the coordination of imine-N atom. In the catalytic path,
the cyclometalation plays an important or/and key role. No CeH
activation products from the aryl ring on the imine-N atom were
observed. This is different from our early publication. Both
Co(PMe3)4 and CoMe(PMe3)4 can activate CeF or CeH bond with
HC]Nas an anchoring group [22]. The Co-methyl group is beneficial
for CeH bond activation because of the thermodynamic contribu-
tion by evolution of methane. A [CNC]-pincer iron(II) complex was
obtained through simultaneous both CeF and CeH activation [23].
The experiments indicate that the bulky substituents on the imine N
atom or the chlorine atom on the aryl ring do not have influence
upon the cross-coupling reaction (Table 2, entries 3, 4 and 7).
Table 3 shows that moderate yields for the mono-methylation
could be reached with stoichiometric amounts of ZnMe2. In
Table 2 ZnMe2 was used in excessive amount (n ¼ 1.2 and 1.5) to
obtain the dimethylated products. It is not easy to find a proper
catalytic condition to get the mono-methylated products without
formation of dimethylated products. With 2,6-diisopropyl-N-
Apart from ZnMe2, other organozinc regents were tried in this
system (Table 4). However, due to the nucleophilicity and steric
hindrance, they show much lower reactivity than ZnMe2. Only in
the case of benzylic zinc chloride, the dibenzylation product could
be obtained quantitatively by raising temperature to 90 ꢀC (Table 4,
entry 3).
3. Conclusion
In conclusion, an active trimethylphosphine supported nickel-
catalyzed cross-coupling reaction of polyfluoroaryl imines with

38
X. Yang et al. / Journal of Organometallic Chemistry 723 (2013) 36e42
Table 2
Ni-catalyzed dimethylation of polyfluoroaryl imines.
F
Ar
Ar
N
N
Ni-catalyst
R
+ n ZnMe2
R
F
Entry
Imine
Dimethylated product
Yield 1/2c (%)
F
F
F
N
F
N
1a
100/94
1b
1a
F
F
F
F
F
F
F
N
N
N
F
F
N
2a
100/89
2b
2a
F
F
F
F
F
F
F
F
N
3a
100/93
3b
3a
F
F
F
F
F
F
F
F
N
4a
100/88
Cl
Cl
4b
4a
F
F
F
F
5a
100/93
100/85
F
F
N
F
F
N
5a
5b
F
F
F
F
F
6b
N
N
N
N
6a
6b
F
F
7b
100/91
7a
7b
a
Ni(PMe3)3Me2 5 mol %, n ¼ 1.2, toluene, 45 ꢀC, 6 h.
Ni(PMe3)4 10 mol %, n ¼ 1.5, toluene, 80 ꢀC, 20 h.
b
c
Yield 1 based on in situ 19F NMR spectra, and yields are average of 2 times; yield 2 is isolated yield.

X. Yang et al. / Journal of Organometallic Chemistry 723 (2013) 36e42
39
Table 3
Ni-catalyzed mono-methylation of polyfluoroaryl imines.
F
F
Ar
Ar
N
N
Ni-catalyst
R
+ 1.0 ZnMe2
R
F
Entry
Imine
Mono-methylated product
Yielde (%)
Ratio (mono-:di-)
F
F
F
F
N
F
F
N
1a
67
67:33
1c
1a
F
F
F
F
F
F
2c
3c
4c
N
F
F
N
F
F
2b
3a
4c
81
81:19
2a
F
F
F
F
3a
F
F
N
F
F
N
N
10
10:90
F
F
F
F
F
4a
F
F
N
F
F
80
80:20
Cl
Cl
F
F
F
5c
F
5a
F
5a
69
69:31
87:13
F
F
N
F
F
N
F
F
F
6a
6c
F
F
F
F
6d
87f
N
N
N
F
F
7c
7a
7d
80f
80:20
N
a
Ni(PMe3)4 5 mol %, toluene, 45 ꢀC, 6 h.
Ni(PMe3)4 5 mol %, toluene, 45 ꢀC, 6.5 h.
Ni(PMe3)4 5 mol %, toluene, 45 ꢀC, 5.5 h.
Ni(PMe3)3Me2 5 mol %, toluene, 80 ꢀC, 2 h.
b
c
d
e
f
Yield based on in situ 19F NMR spectra and yields are average of 2 times.
(Trifluoromethyl)benzene as an internal standard.
ZnMe2 under mild conditions is described. According to the in situ
19F NMR spectroscopic data, the substrates are quantitatively con-
verted into di-methylation products, while mono-methylation can
also be realized under the controlled conditions in moderate yields.
Apart from ZnMe2, other organozinc regents were tried in this
system. However, due to the nucleophilicity and steric hindrance,
they show much lower reactivity than ZnMe2. Only in the case of
benzylic zinc chloride, the dibenzylation product can be obtained

40
X. Yang et al. / Journal of Organometallic Chemistry 723 (2013) 36e42
Table 4
Ni-catalyzed functionalization of 5a with organozinc regentsa.
Entry
RZnX
Conversion (%)
Mono-functionalization yield 1 (%)
Difunctionalization yield 1/2 (%)
1
78
43
35/e
2b
3
100
36
0
5d 100/95
0/e
24
4
<2
trace
trace/e
a
Yield 1 based on in situ 19F NMR spectra and yields are average of 2 times; yield 2 is isolated yield.
Ni(PMe3)4 5 mol %, C6H5CH2ZnCl:5a ¼ 3.0, toluene, 90 ꢀC, 4 h.
b
stirred at 60 ꢀC for 6 h. The reaction mixture was dried under
reduced pressure and extracted three times by pentane and
diethyl ether. The crude product was recrystallized in pentane
or diethyl ether.
quantitatively by raising temperature to 90 ꢀC. The results reported
here will benefit the development of CeF bond activation as well as
the diversity of Schiff bases. Owing to the limitation of the
substrates only seven substances were tested, but we believe this
catalytic system can be expanded to more substrates than tried in
this paper.
B: Nickel-catalyzed dimethylation of N-(2,6-difluorobenzylidene)-
(2,6-diisopropylaniline): To a suspension of an aryl halide
(0.3 mmol) and Ni(PMe3)4 (0.03 mmol) in toluene (3.0 ml), was
injected ZnMe2 (0.45 mmol, in toluene solution) and the
mixture was stirred at 80 ꢀC for 15 h. The reaction mixture was
treated like method A.
4. Experimental section
4.1. General procedures and materials
C: Nickel-catalyzed mono-methylation of (N-((perfluorophenyl)
methylene)aniline): In a Schlenk tube were placed the imines
(0.3 mmol), toluene 3.0 ml and the catalyst Ni(PMe3)4
(0.015 mmol in toluene), then ZnMe2 (0.3 mmol in toluene) was
injected in room temperature. The mixture was heated to 60 ꢀC
for 6 h. The reaction mixture was treated like method A. Because
of the similarity of monofluorinated and bifluorinated products,
a separation by column chromatography or re-crystallization
failed. Therefore, the products are the mixture of mono-
fluorinated and relevant bifluorinated products.
All experiments for cross-coupling reactions were performed
using standard Schlenk techniques under an atmosphere of high
purity nitrogen. 1H, 19F and 13C NMR spectra were recorded on 300
or 400 MHz Bruker instrument. 1H NMR, 13C NMR and 19F NMR are
reported per million (ppm) and are referenced to external standard
(tetramethylsilane: 0 ppm, CDCl3: 76.5 ppm, C6F6 in acetone-d6:
ꢁ162.9 ppm). Coupling constant values were extracted assuming
first-order coupling. The multiplicities are abbreviated as follows:
s ¼ singlet, d ¼ doublet, t ¼ triplet, q ¼ quartet, m ¼ multiplet,
dd ¼ doublet of doublets, td ¼ triplet of doublets. Mass spectra
were recorded on a TOF mass spectrometer.
Na2SO4 and CaCl2 were obtained from commercial sources and
used as received. Acetonitrile was dried by refluxing over CaH2 for
one day. Toluene and pentane and diethyl ether were dried by LiAlH4
for half an hour then used after distillation. ZnMe2 was prepared
from CH3MgBr and ZnCl2 in anhydrous diethyl ether and distillated.
C7H7ZnCl was synthesized by Zn and C7H7Cl in Et2O. C6H11MgCl and
PhMgBr were prepared by C6H11Cl, PhBr with Mg in Et2O. The
concentration was titrated prior to use. Ni(PMe3)3Me2 was prepared
by a published procedure [61]. Imines were prepared by corre-
sponding aldehyde and amines in a small amount of ethanol, and
recrystallized in pentane, diethyl ether or THF [13]. All imines are
light yellow crystals. The yields of imines are from 40% to 60%.
D: Nickel-catalyzed
monomethylation
of
N-(2,6-difluoro-
benzylidene)-(2,6-diisopropylaniline): In a Schlenk tube were
placed the imines (0.3 mmol), toluene 3.0 ml and the catalyst
Ni(PMe3)3Me2 (0.03 mmol in toluene), then ZnMe2 (0.3 mmol in
toluene) was injected in room temperature. The mixture was
heated to 80 ꢀC for 2 h. The reaction mixture was treated like
method A. Because of the similarity of monofluorinated and
bifluorinated products, a separation by column chromatography
orre-crystallizationfailed. Therefore,theproductsarethemixture
of monofluorinated and relevant bifluorinated products.
4.3. Analytical data for products
N-((3,4,5-trifluoro-2,6-dimethylphenyl)methylene)aniline (1b)
(0.36 g, 94%) was obtained from 1a (0.40 g). M. p.: 59.0e60.1 ꢀC. 1H
4.2. General experimental procedure for catalytic reactions
NMR (CDCl3, 300 MHz):
d
8.65 (s, 1H),
d
7.42 (t0, 3JHH ¼ 7.5 Hz, 2H),
3
3
A: Nickel-catalyzed dimethylation of (N-((perfluorophenyl)meth-
ylene)aniline): To a suspension of an aryl halide (0.3 mmol) and
Ni(PMe3)3Me2 (0.015 mmol) in toluene (3.0 ml), was injected
ZnMe2 (0.36 mmol, in toluene solution) and the mixture was
d
7.28 (t, JHH ¼ 6.9 Hz, 1H),
d
7.18 (d, JHH ¼ 7.5 Hz, 2H),
d 2.43 (s,
6H). 19F NMR (CDCl3, 282 MHz):
d
ꢁ140.4 (d, JFF ¼ 20.9 Hz, 2F),
3
d
157.9 (t, 3JFF ¼ 21.5 Hz, 1F). 13C NMR (CDCl3, 75.5 MHz):
d 157.6 (td,
4JCF ¼ 2.3 Hz, 5JCF ¼ 2.3 Hz),
d
151.3 (s),
d
147.2 (ddd, 1JCF ¼ 243.8 Hz,

X. Yang et al. / Journal of Organometallic Chemistry 723 (2013) 36e42
41
3
1
2JCF ¼ 9.8 Hz, JCF ¼ 3.8 Hz),
d
140.0 (dt, JCF ¼ 253.6 Hz,
(m, 3JHH ¼ 6.8 Hz, 2H),
d
2.60 (s, 6H),
d
1.18 (d, 3JHH ¼ 6.9 Hz, 12H).
2JCF ¼ 16.6 Hz),
d
129.0 (td, 3JCF ¼ 3.8 Hz, 4JCF ¼ 3.8 Hz),
d
128.8 (s),
10.8
13C NMR (CDCl3, 75.5 MHz):
d
162.1 (s),
d
149.8 (s),
d
138.6 (s),
122.5 (s),
d
126.0 (s),
d
121.7 (dd, 2JCF ¼ 11.3 Hz, 3JCF ¼ 6.0 Hz),
d
120.1 (s),
d
d
136.9 (s),
27.4 (s),
d
132.0 (s),
d
129.4 (s),
d
128.9 (s),
d
123.5 (s),
d
(s). HRMS (ESI) m/z calcd for C15H12F3N: 263.0922; found:
263.0924.
d
d
23.2 (s), d 21.0 (s). HRMS (ESI) m/z calcd for C21H27N:
293.2143; found: 293.2149.
N-((3,4,5-trifluoro-2,6-dimethylphenyl)methylene)naphthylaniline
(2b) (0.39 g, 89%) was obtained from 2a (0.45 g). M. p.: 107.1e
N-((3,4,5,6-tetrafluoro-2-methylphenyl)methylene)aniline (1c)
1H NMR (CDCl3, 300 MHz):
d
d
8.72 (s,1H),
d
7.42 (t, 3JHH ¼ 7.7 Hz, 2H),
3
3
108.5 ꢀC. 1H NMR (CDCl3, 300 MHz):
d
8.79 (s, 1H),
d
8.24 (m, 1H),
7.28 (t, JHH ¼ 7.2 Hz, 1H),
d
7.20 (d, JHH ¼ 7.5 Hz, 2H),
d 2.62 (s,
3
3
d
7.87 (m, 1H),
d
7.76 (d, JHH ¼ 8.4 Hz, 1H),
d
7.58e7.46 (m, 3H),
3H). 19F NMR (CDCl3, 282 MHz):
d
d
ꢁ141.6 (ddd, JFF ¼ 20.6 Hz,
5
3
d
7.01 (dd, 3JHH ¼ 7.2 Hz, 4JHH ¼ 0.9 Hz, 1H),
d
2.54 (t, 4JHF ¼ 2.0 Hz).
4JFF ¼ 11.0 Hz, JFF ¼ 1.1 Hz, 1F),
ꢁ144.7 (ddd, JFF ¼ 20.6 Hz,
19F NMR (CDCl3, 282 MHz):
d
ꢁ140.3 (d, 3JFF ¼ 21.7 Hz, 2F),
d
ꢁ157.5
4JFF ¼ 11.9 Hz, JFF ¼ 4.5 Hz, 1F),
d
ꢁ152.4 (t0d, JFF ¼ 20.9 Hz,
5
3
(t, JFF ¼ 20.6 Hz, 1F). 13C NMR (CDCl3, 75.5 MHz):
d
158.4 (m),
4JFF ¼ 4.5 Hz, 1F),
d
ꢁ160.1 (t0d, 3JFF ¼ 20.6 Hz, 3JFF ¼ 1.1 Hz, 1F). 13
C
3
d
d
149.6 (s),
d
148.0 (ddd, 1JCF ¼ 244.2 Hz, 2JCF ¼ 9.8 Hz, 3JCF ¼ 3.8 Hz),
NMR (CDCl3, 75.5 MHz): d 152.4 (s), d 151.1 (s), d 147.68 (d,
140.8 (dt, 1JCF ¼ 254.3 Hz, 2JCF ¼ 16.6 Hz),
d
134.2 (s),
d
129.6 (td,
126.7
122.8 (dd, JCF ¼ 11.3 Hz,
11.8 (s). HRMS (ESI) m/z calcd for
1JCF ¼ 252.1 Hz),
d
145.7 (d, JCF ¼ 243.8 Hz),
d
141.2 (d,
d 128.8 (s), d 126.3 (s),
1
3JCF ¼ 3.8 Hz, 4JCF ¼ 3.8 Hz),
d
128.8 (s),
d
128.0 (s),
d
126.8 (s),
d
1JCF ¼ 240.8 Hz),
d
137.8 (d, 1JCF ¼ 234.0 Hz),
2
(s),
d
126.3 (s),
d
126.2 (s),
d
124.0 (s),
d
d 122.1 (s), d 120.2 (s), d 118.5 (s), d 11.4 (s). HRMS (ESI) m/z calcd for
3JCF ¼ 6.0 Hz),
d
112.8 (s),
d
C14H9F4N: 267.0671; found: 267.0670.
C19H14F3N: 313.1078; found: 313.1074.
N-((3,4,5,6-tetrafluoro-2-methylphenyl)methylene)naphthylani-
N-((3,4,5-trifluoro-2,6-dimethylphenyl)methylene)-2,6-diisopro-
pylaniline (3b) (0.41 g, 93%) was obtained from 3a (0.45 g). M.
line (2c) 1H NMR (CDCl3, 300 MHz):
d
8.86 (s, 1H),
d
8.25
3
3
(t0, JHH ¼ 4.8 Hz, 1H),
d
7.87 (t0, JHH ¼ 4.7 Hz, 1H),
d 7.77 (d,
p.: 89.1e90.2 ꢀC. 1H NMR (CDCl3, 300 MHz):
d
8.46 (s, 1H),
d
3JHH ¼ 8.4 Hz, 1H),
d
7.57e7.46 (m, 3H),
d
7.06 (d, 3JHH ¼ 6.6 Hz, 1H),
3
4
5
7.23e7.10 (m, 3H),
d
2.98 (m, JHH ¼ 6.9 Hz, 2H),
d
2.49 (t,
d
2.77 (dd, JHF ¼ 3.0 Hz, JHF ¼ 1.2 Hz, 3H). 19F NMR (CDCl3,
3
4JHF ¼ 2.0 Hz, 6H),
d
1.20 (d, JHH ¼ 6.9 Hz, 12H). 19F NMR (CDCl3,
282 MHz):
d
ꢁ141.6 (ddd, 3JFF ¼ 21.2 Hz, 4JFF ¼ 11.9 Hz, 5JFF ¼ 1.4 Hz,
3
282 MHz):
d
ꢁ140.3 (d, 3JFF ¼ 20.1 Hz, 2F),
d
ꢁ157.2 (t, 3JFF ¼ 20.6 Hz,
1F),
d
ꢁ144.6 (ddd, JFF ¼ 20.9 Hz, 4JFF ¼ 11.9 Hz, 5JFF ¼ 4.8 Hz, 1F),
1F). 13C NMR (CDCl3, 75.5 MHz):
d
160.6 (s),
d
149.7 (s),
d
148.0 (ddd,
d
ꢁ152.1 (t0d, JFF ¼ 20.9 Hz, JFF ¼ 4.8 Hz, 1F),
d
ꢁ160.0 (t0,
3
4
1JCF ¼ 243.0 Hz, JCF ¼ 9.8 Hz, JCF ¼ 3.8 Hz),
d
140.9 (d,
123.4 (s), 123.0
23.9 (s), 11.6 (s).
3JFF ¼ 20.6 Hz, 1F). 13C NMR (CDCl3, 75.5 MHz):
d 152.4 (m), d 148.6
2
3
1JCF ¼ 253.6 Hz),
d
137.4 (s),
d
128.7 (s),
d
124.7 (s),
28.2 (s),
d
d
(s),
d
147.9 (d, 1JCF ¼ 264.9 Hz),
d
145.7 (d, 1JCF ¼ 240.7 Hz),
d 139.8 (d,
2
3
(dd, JCF ¼ 11.3 Hz, JCF ¼ 6.0 Hz),
d
d
d
1JCF ¼ 234.7 Hz),
d
137.8 (d, 1JCF ¼ 239.2 Hz),
d
d
133.5 (s),
125.5 (s),
d
128.1 (s),
123.2 (s),
HRMS (ESI) m/z calcd for C21H24F3N: 347.1861; found: 347.1853.
N-((3,4,5-trifluoro-2,6-dimethylphenyl)methylene)-2-Cl-aniline
(4b) (0.37 g, 88%) was obtained from 4a (0.45 g). M. p.: 94.9e
d
d
127.3 (s),
d
126.4 (s),
d
126.1 (s),
d
125.7 (s),
d
2
122.21 (d, JCF ¼ 17.4 Hz),
d
118.6 (s), d 111.9 (s), d 11.8 (s). HRMS
(ESI) m/z calcd for C18H11F4N: 317.0828; found: 317.0834.
95.6 ꢀC. 1H NMR (CDCl3, 300 MHz):
d
8.62 (s, 1H),
d
7.47 (d,
N-((3,4,5,6-tetrafluoro-2-methylphenyl)methylene)-2,6-diisopro-
pylaniline (3c) HRMS (ESI) m/z calcd for C20H21F4N: 351.1610;
found: 351.1604. A try to isolate 3c failed because of the low yield.
N-((3,4,5,6-tetrafluoro-2-methylphenyl)methylene)-2-Cl-aniline
3JHH ¼ 7.8 Hz, 1H),
d
7.31 (t0, JHH ¼ 7.4 Hz, 1H),
d
7.18 (t0,
3
3JHH ¼ 7.5 Hz, 1H),
d
7.00 (d, JHH ¼ 7.5 Hz, 1H),
d
2.49 (s, 6H). 19
F
3
NMR (CDCl3, 282 MHz):
d
ꢁ140.2 (d, 3JFF ¼ 20.3 Hz, 2F),
ꢁ157.1 (t,
d
3JFF ¼ 21.3 Hz, 1F). 13C NMR (CDCl3, 75.5 MHz):
d
160.4 (s),
d
149.8
141.0
(4c) 1H NMR (CDCl3, 300 MHz):
d 8.69 (s, 1H), d 7.46 (d,
(s),
d
147.9 (ddd, 1JCF ¼ 243.0 Hz, 2JCF ¼ 10.6 Hz, 3JCF ¼ 3.8 Hz),
d
3JHH ¼ 8.1 Hz, 1H),
d
7.30 (t, 3JHH ¼ 7.5 Hz, 1H),
d 7.21e7.15 (m, 1H),
1
2
4
(dt, JCF ¼ 254.3 Hz, JCF ¼ 17.0 Hz),
d
130.3 (s),
127.1 (s),
11.7 (s). HRMS (ESI) m/z
d
129.1 (t,
d
7.10e6.98 (m, 1H),
d
2.70 (d, JHF ¼ 1.8 Hz, 3H). 19F NMR (CDCl3,
3JCF ¼ 4.5 Hz),
d
127.9 (s),
d
127.7 (s),
120.0 (s),
d
d
122.9 (dd,
282 MHz):
d
ꢁ141.4 (dd, 3JFF ¼ 21.2 Hz, 4JFF ¼ 11.3 Hz, 1F),
d
ꢁ144.8
2JCF ¼ 10.6 Hz, 3JCF ¼ 6.4 Hz),
d
d
(ddd, JFF ¼ 20.6 Hz, 4J ¼ 11.6 Hz, JFF ¼ 4.8 Hz, 1F),
d
ꢁ151.6 (t0d,
3
5
calcd for C15H11ClF3N: 297.0532; found: 297.0531.
3JFF ¼ 20.6 Hz, 4JFF ¼ 4.8 Hz, 1F),
d
ꢁ160.2 (t0, 3JFF ¼ 20.6 Hz, 1F). 13
C
N-((3,4,5-trifluoro-2,6-dimethylphenyl)methylene)-4-methyl-
aniline (5b) (0.43 g, 93%) was obtained from 5a (0.48 g). M.
NMR (CDCl3, 75.5 MHz): d 154.1 (m), d 148.6 (s), d
147.9 (ddt0,
1JCF ¼ 252.1 Hz, JCF ¼ 10.6 Hz, JCF ¼ 3.0 Hz),
d 145.7 (dddd,
2
3
p.: 52.5e53.9 ꢀC. 1H NMR (CDCl3, 300 MHz):
d
8.65(s, 1H),
d
7.22 (d,
1JCF ¼ 243.4 Hz, JCF ¼ 9.8 Hz, JCF ¼ 3.8 Hz, JCF ¼ 1.5 Hz),
d
141.4
2
3
4
3
1
1
3JHH ¼ 8.1 Hz, 2H),
d
7.11 (d, JHH ¼ 8.1 Hz, 2H),
d
2.41 (s, 6H, CH3),
(dm, JCF ¼ 258.1 Hz),
d
137.8 (dm, JCF ¼ 250.9 Hz),
d 129.6 (s),
2
d
2.39 (s, 3H). 19F NMR (CDCl3, 282 MHz):
d
ꢁ140.5 (d, 3JFF ¼ 20.3 Hz,
d
127.8 (s),
d
127.2 (s),
d
126.8 (s),
d
122.7 (dd, JCF ¼ 15.5 Hz,
3
2F),
d
d
ꢁ158.2 (t, JFF ¼ 21.0 Hz, 1F). 13C NMR (CDCl3, 75.5 MHz):
3JCF ¼ 4.2 Hz),
d
118.8 (s),
d
118.1 (m), d
11.7 (d, 4JCF ¼ 4.5 Hz). HRMS
2
156.7 (s),
d
148.7 (s),
d
147.2 (ddd, 1JCF ¼ 243.8 Hz, JCF ¼ 9.8 Hz,
(ESI) m/z calcd for C14H8ClF4N: 301.0281; found: 301.0275.
N-((3,4,5,6-tetrafluoro-2-methylphenyl)methylene)-4-methyl-
3JCF ¼ 3.8 Hz),
d
139.9 (dt, 1JCF ¼ 252.8 Hz, 2JCF ¼ 16.6 Hz),
d
136.0 (s),
121.6 (dd,
10.8 (s). HRMS
3
4
d
129.4 (s),
d
129.2 (td, JCF ¼ 4.5 Hz, JCF ¼ 4.5 Hz),
d
aniline (5c) 1H NMR (CDCl3, 300 MHz):
d 8.72 (s, 1H), d 7.22 (d,
2JCF ¼ 11.3 Hz, 3JCF ¼ 6.0 Hz),
d
120.1 (s),
d
20.5 (s),
d
3JHH ¼ 8.1 Hz, 2H),
d
7.12 (m, 2H),
d
2.61 (dd, JHF ¼ 3.0 Hz,
4
(ESI) m/z calcd for C16H14F3N: 277.1078; found: 277.1075.
N-((2,6-dimethylphenyl)methylene)naphthylaniline
5JHF ¼ 1.4 Hz, 3H),
d
2.39 (s, 3H). 19F NMR (CDCl3, 282 MHz):
d
ꢁ141.7
ꢁ144.8
ꢁ152.9
3
4
5
(6b)
(ddd, JFF ¼ 21.5 Hz, JFF ¼ 11.9 Hz, JFF ¼ 1.1 Hz, 1F),
d
3
4
5
(0.37 g, 85%) was obtained from 6a (0.45 g). M. p.: 176.5e177.7 ꢀC.
(ddd, JFF ¼ 20.9 Hz, JFF ¼ 11.9 Hz, JFF ¼ 4.2 Hz, 1F),
d
1H NMR (CDCl3, 300 MHz):
d
8.94 (s, 1H),
d
8.31 (t, JHH ¼ 4.8 Hz,
(t0d, JFF ¼ 20.6 Hz, JFF ¼ 4.2 Hz, 1F),
d
ꢁ160.3 (t0d, JFF ¼ 20.9 Hz,
3
3
4
3
1H),
H, 3H),
2H),
d
7.86 (m, 1H),
d
7.72 (d, 3JHH ¼ 8.4 Hz, 1H),
d
7.55e7.45 (m, Are
7.15e7.13 (m,
2.67 (s, 6H). 13
4JFF ¼ 1.1 Hz, 1F). 13C NMR (CDCl3, 75.5 MHz):
d 151.9 (s), d 149.0 (s),
1
2
d
7.24 (dd, 3JHH ¼ 6.6 Hz, 4JHH ¼ 1.8 Hz, 1H),
d
d
148.0 (dd, JCF
¼
251.3 Hz, JCF
¼
9.1 Hz),
d
146.1 (dd,
141.6 (dm, JCF ¼ 231.7 Hz),
136.9 (s), 129.9 (s), 122.4
120.7 (s), 119.1 (m), 29.7 (s),
2
1
d
7.01 (dd, 3JHH ¼ 7.2 Hz, 4JHH ¼ 0.9 Hz, 1H),
d
C
1JCF ¼ 242.6 Hz, JCF ¼ 9.4 Hz),
d
1
NMR (CDCl3, 75.5 MHz):
d
160.5 (s),
128.6 (s),
125.2 (s),
d
150.0 (s),
128.2 (s),
d
138.3 (s),
127.2 (s),
112.2 (s),
d
133.5
125.9
d
138.3 (dm, JCF ¼ 214.3 Hz),
d
d
d
(s),
(s),
d
132.8 (s),
125.7 (s),
d
129.4 (s),
d
d
d
d
(dd, 2JCF ¼ 15.5 Hz, 3JCF ¼ 4.2 Hz),
d
d
d
d
d
125.4 (s),
d
d
123.7 (s),
d
d
21.0 (s).
d 11.9 (s). HRMS (ESI) m/z calcd for C15H11F4N: 281.0828; found:
HRMS (ESI) m/z calcd for C19H17N: 259.1361; found: 259.1370.
N-(2,6-dimethyl-benzylidene)-2,6-diisopropylaniline
281.0820.
N-((2-methyl-6-fluoro-phenyl)methylene)naphthylaniline (6c)
(7b)
(0.21 g, 91%) was obtained from 7a (0.24 g). M. p.: 50.4e51.8 ꢀC. 1H
1H NMR (CDCl3, 300 MHz):
d
8.98 (s, 1H),
d
8.31 (s, 1H),
d 7.85 (d,
NMR (CDCl3, 300 MHz):
d
8.59 (s, 1H),
d
7.23e7.07 (m, 6H),
d
3.05
3JHH ¼ 4.8 Hz, 1H),
d
7.72 (d, 3JHH ¼ 8.1 Hz, 1H),
d
7.50e7.45 (m, 3H),

42
X. Yang et al. / Journal of Organometallic Chemistry 723 (2013) 36e42
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d
7.32 (m, 1H), d 7.15e6.98 (m, 3H), d
2.88 (s, 3H). 19F NMR (CDCl3,
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4695e4697.
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28 (2009) 5771e5776.
[21] Z. Lian, X. Xu, H. Sun, Y. Chen, T. Zheng, X. Li, Dalton Trans. 39 (2010)
9523e9529.
[22] T. Zheng, H. Sun, J. Ding, Y. Zhang, X. Li, J. Organomet. Chem. 695 (2010)
1873e1877.
282 MHz):
d
ꢁ117.9 (s, 1F). 13C NMR (CDCl3, 75.5 MHz):
d
163.4 (d,
141.0 (s),
127.0 (s),
113.1 (s),
1JCF ¼ 252.8 Hz),
d
155.2 (d, JCF ¼ 6.0 Hz),
d
149.69 (s), d
d
d
d
133.7 (s),
126.1 (s),
112.8 (s),
d
131.2 (d, JCF ¼ 9.8 Hz),
125.8 (s), 125.6 (s),
112.2 (s),
d
128.5 (s),
d
127.4 (s),
d
d
d
d 123.8 (s), d 122.3 (s),
22.14 (s). HRMS (ESI) m/z calcd for C18H14FN:
d
d
d
263.1110; found: 263.1117.
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3122e3126.
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(2012) 1349e1360.
[26] J.A. Hatnean, S.A. Johnson, Organometallics 31 (2012) 1361e1373.
[27] T. Wang, L. Keyes, B.O. Patrick, J.A. Love, Organometallics 31 (2012)
1397e1407.
[28] A. Steffen, M.I. Sladek, T. Braun, B. Neumann, H.-G. Stammler, Organometallics
24 (2005) 4057e4064.
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L. Holland, J. Am. Chem. Soc. 127 (2005) 7857e7870.
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5321e5324.
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N-(2-methyl-6-fluoro-benzylidene)-2,6-diisopropylaniline (7c)
1H NMR (CDCl3, 300 MHz):
d 8.59 (s,1H), d 7.35e6.97 (m, 6H), d 3.00
(m, 3JHH ¼ 6.9 Hz, 2H),
d
2.74 (s, 3H),
d
1.19 (d, 3JHH ¼ 6.9 Hz,12H). 19
F
NMR (CDCl3, 282 MHz):
d
ꢁ118.5 (s,1F). 13C NMR (CDCl3, 75.5 MHz):
1
2
d
163.0 (d, JCF ¼ 251.8 Hz),
140.5 (s), 136.8 (s),
123.7 (s),
(d, JCF ¼ 21.9 Hz), 27.5 (s),
d
157.6 (d, JCF ¼ 9.8 Hz),
d
d
149.7 (s),
126.7 (d,
d 112.9
2
d
d
d
130.9 (d, JCF ¼ 10.6 Hz),
JCF ¼ 3.0 Hz),
d
d
122.5 (s),
d
121.8 (d, JCF ¼ 7.6 Hz),
d
d
23.1 (s),
d
21.3 (d, 5JCF ¼ 2.3 Hz). HRMS
(ESI) m/z calcd for C20H24FN: 297.1893; found: 297.1887.
N-((3,4,5-trifluoro-2,6-dibenzylphenyl)methylene)-4-methyl-
aniline (5d) (0.64 g, 95%) was obtained from 5a (0.45 g). M. p.:
105.7e106.8 ꢀC. 1H NMR (CDCl3, 300 MHz):
d
8.42 (s, 1H),
d
7.26e
3
7.09 (m, 12H),
d
6.76 (d, JHH ¼ 8.4 Hz, 2H),
d 4.31 (s, 4H), d 2.34
(s, 3H). 19F NMR (CDCl3, 282 MHz):
d
ꢁ138.46 (d, 3JFF ¼ 21.2 Hz, 2F,
3
Aryl-Fm),
100 MHz):
d
ꢁ156.8 (t, JFF ¼ 21.2 Hz, 1F, Aryl-Fp). 13C NMR (CDCl3,
d
156.9 (s),
d
148.6 (d, JCF ¼ 2.0 Hz),
d
148.5 (ddd,
d 140.4 (dt,
1JCF ¼ 246.0 Hz, JCF ¼ 10.0 Hz, JCF ¼ 4.0 Hz),
2
3
1JCF ¼ 253.0 Hz, 2JCF ¼ 17.0 Hz),
d
139.0 (s),
128.3 (s), 126.4 (s),
120.6 (s), d 30.6 (s),
d
136.5 (d, JCF ¼ 3.0 Hz),
d
130.5 (s),
d
129.8 (s),
d
128.6 (s),
d
d
d
d
125.3 (td,
20.98 (d,
3JCF ¼ 6.0 Hz, JCF ¼ 6.0 Hz),
d
4
J ¼ 3.0 Hz). HRMS (ESI) m/z calcd for C28H22F3N: 4 29.1704; found:
429.1744.
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Acknowledgments
This work was supported by NSF China No. 21172132.
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