Iron-catalyzed direct sulfenylation and selenylations of phenylpyrazoles: Synthesis of fipronil derivatives with disulfides promoted by a catalytic amount of iodine

Article abstract of DOI:10.1080/00397911.2011.584262

The direct thiolation of phenylpyrazole with disulfide using the FeBr ₃/I₂ complex as the catalyst in MeCN at 80 °C was reported. With the optimum conditions, several fipronil derivatives of 4-sulfenylpyrazole were synthesized by the reaction of 5-amino-1-[2,6-dichloro- 4-(trifluoromethyl)phenyl-lH-pyrazole-3-arbonitrile (1a) with disulfides (2) in moderate to good yields. The coupling reaction with diaryl diselane also occurred under similar conditions.

Full text of DOI:10.1080/00397911.2011.584262

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Iron-Catalyzed Direct Sulfenylation
and Selenylations of Phenylpyrazoles:
Synthesis of Fipronil Derivatives with
Disulfides Promoted by a Catalytic
Amount of Iodine
Mei Xu a , Xiao Hong Zhang a & Ping Zhong a b
a College of Chemistry and Materials Science, Wenzhou University ,
Wenzhou , China
b Oujiang College, Wenzhou Universtity , Wenzhou , China
Accepted author version posted online: 12 Jan 2012.Published
online: 02 Aug 2012.
To cite this article: Mei Xu , Xiao Hong Zhang & Ping Zhong (2012) Iron-Catalyzed Direct
Sulfenylation and Selenylations of Phenylpyrazoles: Synthesis of Fipronil Derivatives with
Disulfides Promoted by a Catalytic Amount of Iodine, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 42:23, 3472-3481, DOI:
10.1080/00397911.2011.584262
To link to this article: http://dx.doi.org/10.1080/00397911.2011.584262
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Synthetic Communications1, 42: 3472–3481, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2011.584262
IRON-CATALYZED DIRECT SULFENYLATION AND
SELENYLATIONS OF PHENYLPYRAZOLES: SYNTHESIS
OF FIPRONIL DERIVATIVES WITH DISULFIDES
PROMOTED BY A CATALYTIC AMOUNT OF IODINE
Mei Xu,1 Xiao Hong Zhang,1 and Ping Zhong1,2
1College of Chemistry and Materials Science, Wenzhou University,
Wenzhou, China
2Oujiang College, Wenzhou Universtity, Wenzhou, China
GRAPHICAL ABSTRACT
Abstract The direct thiolation of phenylpyrazole with disulfide using the FeBr3/I2 complex
as the catalyst in MeCN at 80 ꢀC was reported. With the optimum conditions, several fipronil
derivatives of 4-sulfenylpyrazole were synthesized by the reaction of 5-amino-1-[2,6-
dichloro-4-(trifluoromethyl)phenyl-lH-pyrazole-3-arbonitrile (1a) with disulfides (2) in
moderate to good yields. The coupling reaction with diaryl diselane also occurred under similar
conditions.
Keywords Direct thiolation; FeBr3=I2-catalyzed system; fipronil derivatives; selenylpyra-
zole; sulfenylpyrazole
INTRODUCTION
N-Phenylpyrazole derivatives have attracted great attentions because of their
biological activities.[1] For example, fipronil,[2] 5-amino-1-(2,6-dichloro-4-trifluoro-
methylphenyl)-4-trifluoromethylsulfinyl-lH-pyrazole-3-carbonitrile (I, Fig. 1), is an
important phenylpyrazole insecticide. Moreover, many fipronil analogs that have a
thio group, such as fipronil sulfide (II),[3] sulfone (III),[4] and ethiprole (IV), with
4-EtSO replacing the 4-CF3SO of (I) or ethiprole sulfide (V),[5] were also surprisingly
Received March 17, 2011.
Address correspondence to Xiao Hong Zhang or Ping Zhong, College of Chemistry and Materials
Science, Wenzhou University, Wenzhou 325035, China. E-mail: kamenzxh@163.com; zhongp0512@163.com
3472

SYNTHESIS OF FIPRONIL DERIVATIVES
3473
Figure 1. Fipronil (I) and analogs (II, III, IV, V).
found to have the same insecticidal activity. We believe that the fipronil derivatives of
4-sulfenylpyrazole, with 4-alkyl(aryl) thio replacing 4-CF3SO of (I), may have the
same high insecticidal activity.
The traditional synthesis of sulfenylpyrazole often used RSCl or ArSCl,[6] which
are very toxic and difficult to prepare. Lin et al. and Lange et al.[7] have reported
preparation of the 4-sulfenylpyrazole based on the reaction of 4-bromopyrazole with
disulfide, which was undesirable from the viewpoint of atom economy. The synthesis
of sulfenylpyrazole by other ways was reported rarely. In our group, we have been
devoted to exploring different ways to introduce thio groups at the pyrazole moiety.
For example, in 2006, we introduced alkylthio at the pyrazole ring by the reaction
of 5-amino-1-(2,6-dichloro-4-trifluoromethylphenyl)-3-cyanopyrazolyldisulfied with
alkyl halide in the presence of sodium dithionite at room temperature.[8] In 2008,
alkenyl sulfides of pyrazole were synthesized by the reaction of disulfied with terminal
alkynes in the presence of CuI, rongalite, and Cs2CO3.[9] Subsequently, a novel and
solvent-free protocol for the synthesis of sulfenylpyrazole by the copper-catalyzed
oxidative S-arylation of disulfides with aryltrimethoxysilanes was reported.[10] We
also have sucessfully synthesized sulfenylpyrazole by the reaction of disulfiedes with
organoboronic acids in the presence of copper catalysts.[11]
However, in view of these different methods, 5-amino-1-(2,6-dichloro-4-
trifluoromethylphenyl)-3-cyanopyrazolyl disulfide must be synthesized based on the
reaction of 5-amino-1-(2,6-dichloro-4-trifluoromethylphenyl)-3-cyanopyrazolyl (1a)
with S2Cl2, which had a foul odor. We envisioned that sulfenylpyrazole could be
Scheme 1.

3474
M. XU, X. H. ZHANG, AND P. ZHONG
synthesized by the direct thiolation of pyrazole with disulfide, considering that the
direct thiolation of hetercycles compounds is of current interest. Here, we report a
protocol for the direct thiolation of phenylpyrazole with disulfide using the FeBr3=
I2 complex as the catalyst in MeCN at 80 ꢀC (Scheme 1). Moreover, the coupling
reaction of pyrazole with diaryl diselane also occurred under similar conditions.
We started with the coupling reaction of 5-amino-1-[2,6-dichloro-4-(trifluoro-
methyl)phenyl-lH-pyrazole-3-carbonitrile (1a) with 1,2-diphenyldisulfane (2a) to
assess the catalyst activity and determine the optimal reaction conditions, and the
results are summarized in Table 1. Initially, a series of Lewis acids, including FeF3,
Table 1. Screening optimal conditionsa
Solvent Isolated
yieldb (%)
Entry
Fe (mol %)
FeF3 (10) MeCN
1
2
66
76
FeCl3 (10) MeCN
FeBr3 (10) MeCN
Fe(C5H7O2 MeCN)3 (10)
3
82
20
c
4
d
5
Fe(C5H7O2 MeCN F3)3 (10)
FeBr3 (10) MeCN
— MeCN
75
6e
7f
0
50
8
FeBr3 (5) MeCN
FeBr3 (20) MeCN
FeBr3 (10) MeCN
FeBr3 (10) MeCN
FeBr3 (10) DCE
FeBr3 (10) tolune
FeBr3 (10) THF
FeBr3 (10) DMF
FeBr3 (10) MeCN
70
82
9
10g
11h
12
13
14
15
16i
52
23
50
66
23
Trace
81
aReaction conditions: 1a (0.4 mmol), 2a (0.2 mmol), Fe (10 mol%),
and I2 (10 mol%) in solvent (3 mL) at 80 ꢀC for 42 h.
bIsolated yield.
cThe structure
dThe structure
.
.
eWithout I2.
fI2 (100 mol%).
gAt 100 ꢀC.
hAt room temperature.
iUnder N2..

SYNTHESIS OF FIPRONIL DERIVATIVES
3475
Table 2. Synthesis of 4-sulfenylated pyrazole by FeBr3=I2-catalyzed 4-sulfenylation of disulfides (2b–2h)
with pyrazoles (1a, 1b, 1c)a
Entry
Pyrazole 1a–c
R1
Product
Yield (%)b
1
4-MeC6H4 (2b)
3ab(11)
92
2
3
(1a)
(1a)
4-MeOC6H4 (2c)
4-ClC6H4 (2d)
3ac(11)
3ad(11)
3ae(11)
3af
73
93
4
5
6
(1a)
(1a)
(1a)
4-FC6H4 (2e)
3-FC6H4 (2f)
4-NO2C6H4 (2 g)
95
55
Trace
7
(1a)
Benzyl (2 h)
3ah(11)
90
8
9
(2a)
(2c)
3ba
3bc
74
90
(1b)
10
11
(2a)
(2c)
3ca
3cc
75
64
(1c)
aReaction conditions: 1 (0.4 mmol), 2 (0.2 mmol), FeBr3 (10 mol%), and I2 (10 mol%) in MeCN (3 mL)
at 80 ꢀC for 42 h.
bIsolated yield.
FeCl3, FeBr3, iron (III) 2, 4-pentanedionate [Fe(C5H7O2)3], and iron(III) trifluoro-
pentanedirnat [Fe(C5H7O2F3)3], were tested (entries 1–5). We found that the yield
is 82% in the presence of FeBr3 after 42 h at 80 ꢀC (entry 3), and that the other Lewis
acid catalysts were inferior to FeBr3. Moreover, FeBr3 was found to be less effective
in the absence of iodine (entry 6), while 50% yield of product 3aa was isolated using
100 mol% of iodine alone (entry 7). Among the amounts of FeBr3 and the reaction
temperatures examined, 20 mol% of FeBr3 combined with 80 ꢀC gave the same
and the best yield (entry 7) with the 10 mol% of FeBr3. A number of other solvents
were also examined [dichloroethane (DCE), toluene, tetrahydrofuran (THF),

3476
M. XU, X. H. ZHANG, AND P. ZHONG
Table 3. Synthesis of 4-selenylated pyrazole by FeBr3=I2-catalyzed 4-selenylations of diselenides (2i–2j)
with pyrazoles (1a, 1b, 1c)a
Entry
Pyrazole 1
R2
Product
Yield (%)b
1
Phenyl (2i)
4ai
46
2
3
4
(1a)
(1b)
benzyl (2j)
(2i)
4aj
4bi
4bj
78
32
56
(2j)
5
6
(2i)
(2j)
4ci
4cj
55
53
(1c)
aReaction conditions: 1 (0.4 mmol), 2i and j (0.2 mmol), FeBr3 (10 mol%), and I2 (10 mol%) in MeCN
(3 mL) at 80 ꢀC for 42 h.
dimethylformamide (DMF); entries 12–15], and they were less effective than aceonitrile.
We then examined the scope with respect to phenylpyrazole 1a, 1b, 1c and disulfides
2b–2h under the optimized conditions; typical results are shown in Table 2. Initially,
a variety of disulfides were examined with pyrazole (1a) (entries 1–7). The results
demonstrated that diaryldisulfides 2b–2g, bearing either electron-donating or
electron-withdrawing groups, underwent direct thiolation of pyrazole (1a) (entries
1–5) smoothly, but the disulfide with nitro groups 2g gave an unsatisfactory result
(entries 6). To our delight, the reaction conditions are compatible with dialkyl disul-
fides 1; 2-dibenzyldisulfane (2h), for instance, underwent the reaction with pyrazole

SYNTHESIS OF FIPRONIL DERIVATIVES
3477
Scheme 2. Working mechanism.
(1a), FeBr3, and I2 smoothly in 90% yield (entry 7). Subsequently, other substituted
pyrazoles 1b and 1c were investigated (entries 8–11) under the standard conditions.
It was noteworthy to discover that the reaction can give good yields.
The direct selenylation of pyrazoles with 1,2-diphenyl diselane and 1,2-dibenyl-
diselane were also tested under the standard conditions, and the results are summar-
ized in Table 3. In the presence of FeBr3 and I2, pyrazoles 1a, 1b, and 1c underwent the
4-selenylation reaction with 1,2-diphenyl diselane and 1,2-dibenyl diselane smoothly
to afford the corresponding 4-selenylated pyrazoles in moderate to good yields.
A possible working mechanism, as outlined in Scheme 2, was proposed on the
basis of reported mechanisms.[12] The reaction can take place in the presence of iodine
alone (Table 1, entry 6), which suggests an electrophilic addition process. Initially,
intermediate RSI (A), which is afforded in situ by the reaction of RSSR (2) with I2,
undergoes the electrophilic addition to 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)
phenyl-lH-pyrazole-3-carbonitrile (1), leading to intermediate B with the aid of FeBr3
catalyst. Deprotonation of intermediate B gives the desired product and HI. The
reaction of HI with RSSR (2) may take place to provide the active intermediate
RSI (A) and an inactive RSH intermediate.
In summary, we have developed a protocol for the synthesis of sulfenylated
pyrazoles via iron-catalyzed direct thiolation of pyrazoles and disulfides with the
aid of I2. In comparison with the reported synthesis of sulfenylpyrazole, the present
FeBr3=I2 system has advantages of good efficiency, simple operation, low cost, and
security for regioselective sulfenylation of pyrazole. Moreover, the direct selenylation
of pyrazoles with 1,2-diphenyldiselane and 1,2-dipbenyldiselane are also conducted
efficiently to afford the corresponding 4-selenated pyrazoles in moderate to good
yields using the FeBr3=I2 system.
EXPERIMENTAL
Chemicals were either purchased or purified by standard techniques. 1H NMR
and 13C NMR spectra were measured on a 300-MHz spectrometer (1H, 300 MHz;

3478
M. XU, X. H. ZHANG, AND P. ZHONG
13C, 125 MHz), using CDCl3 and actone-d6 as the solvent with tetramethylsilane
(TMS) as an internal standard at room temperature. The coupling constants J are
given in hertz (Hz). The high-resolution mass spectrometer was a Waters Micromass
GCT Premier (EIþ, 70 eV). All reactions are happen under an air atmosphere.
Column chromatography was performed using EM silica gel 60 (300–400 mesh).
Typical Experimental Procedure of the Iron-Catalyzed Sulfenylations
of Pyrazoles (1) with Disulfides (2) in the Presence of I2
A mixture of 5-amino-1-[2, 6-dichloro-4-(trifluoro methyl)-phenyl pyrazole-
3-carbonitrile 1a (0.2 mmol), 1,2-diphenyldisulfane 2a (0.1 mmol), FeBr3 (10 mol%),
and I2 (10 mol%) in MeCN (3 mL) was stirred at 80 ꢀC for the indicated time until
complete consumption of starting material as monitored by thin-layer chromato-
graphy (TLC). After the reaction was finished and cooled down, the mixture was
poured into ethyl acetate, which was dried over anhydrous Mg2SO4, and evaporated
under vacuum. The residue was purified by flash column chromatography (petroleum
ether=ethyl acetate) to afford the desired product.
5-Amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-(3-fluorophenyl)
thio-1H-pyrazole-3-carbonitrile (3af)
White solid, mp 242–244 ꢀC (uncorrected); 1H NMR (500 MHz, acetone-d6) d:
7.27 (s, 2H), 6.65–6.50 (m, 1H), 6.18–6.02 (m, 3H), 5.52 (brs, 2H); 13C NMR
(125 MHz, actone-d6) d: 164.0 (d, J ¼ 245.2 Hz), 153.3, 140.7, 137.3, 136.7, 134.8 (q,
J ¼ 34.0 Hz), 133.1, 131.8, 127.4, 123.3 (q, J ¼ 271.5 Hz), 122.1, 113.3 (d, J ¼ 21.5 Hz),
113.2, 112.8 (d, J ¼ 24.5 Hz), 89.5; LRMS (EI, 70 eV) m=z (%): 446 (Mþ, 100); HRMS
(ESI) for C17H8Cl2F4N4S (Mþ) calcd.: 445.9783; found: 445.9782.
5-Amino-1-[2-chloro-4-(trifluoromethyl)phenyl]-4-phenythio-1H-
pyrazole-3-carbonitrile (3ba)
1
White solid, mp 136–137 ꢀC (uncorrected); H NMR (300 MHz, actone-d6) d:
7.30 (s, 1H), 7.17–7.10 (m, 2H), 6.49–6.31 (m, 5H), 5.25 (brs, 2H); 13C NMR
(125 MHz, actone-d6) d: 153.3, 137.9, 136.5, 132.8, 132.3 (2C), 129.9 (q, J ¼ 45.0 Hz,
1C), 129.7, 128.7, 128.6, 126.7 (2C), 126.6, 122.8 (q, J ¼ 271.3 Hz, 1C), 113.7, 102.3,
90.7; LRMS (EI, 70 eV) m=z (%): 394 (Mþ, 100). HRMS (ESI) for C17H10ClF3N4S
(Mþ) calcd.: 394.0267; found: 394.0270.
5-Amino-1-[2-chloro-4-(trifluoromethyl)phenyl]-4-(4-methoxyphenyl)
thio-1H-pyrazole-3-carbonitrile (3bc)
1
White solid, mp 130–131 ꢀC (uncorrected); H NMR (300 MHz, actone-d6) d:
8.07 (s, 1H), 7.97–7.89 (m, 2H), 7.23 (d, J ¼ 9.0 Hz, 2H), 6.87 (d, J ¼ 9.0 Hz, 2H),
6.02 (brs, 2H), 3.74 (s, 3H); 13C NMR (125 MHz, actone-d6) d: 159.7, 152.8, 137.8,
136.6, 132.8, 132.0, 130.9 (q, J ¼ 33.4 Hz, 1C), 130.3 (2C), 129.6, 128.6, 128.1, 124.1
(q, J ¼ 270.3 Hz, 1C), 115.8 (2C), 113.9, 93.3, 55.7; LRMS (EI, 70eV) m=z (%): 424
(Mþ, 100). HRMS (ESI) for C18H12ClF3N4OS (Mþ) calcd.: 424.0374; found: 424.0374.

SYNTHESIS OF FIPRONIL DERIVATIVES
3479
5-Amino-1-[2-chloro-5-(trifluoromethyl)phenyl]-4-phenylthio-1H-
pyrazole-3-carbonitrile (3ca)
1
White solid, mp 142–143 ꢀC (uncorrected) (lit.1 mp 136–137 ꢀC); H NMR
(300 MHz, actone-d6) d: 7.28 (s, 1H), 7.15–7.08 (m, 2H), 6.47–6.29 (m, 5H), 5.22
(brs, 2H); 13C NMR (125 MHz, actone-d6) d: 153.3, 137.9, 136.5, 132.8, 132.3,
131.2, 130.8 (q, J¼ 33.5 Hz, 1C), 130.1 (2C), 129.7, 128.6, 126.7 (2C), 126.6, 124.3
(q, J¼270.4 Hz, 1C), 113.7, 90.8; LRMS (EI, 70 eV) m=z (%): 394 (Mþ, 100). HRMS
(ESI) for C17H10ClF3N4S (Mþ) calcd.: 394.0267; found: 394.0266.
5-Amino-1-[2-chloro-5-(trifluoromethyl)phenyl]-4-(4-methoxyphenyl)
thio-1H-pyrazole-3-carbonitrile (3cc)
1
White solid, mp 127–129 ꢀC (uncorrected); H NMR (300 MHz, actone-d6) d:
7.22 (s, 1H), 7.12–7.05 (m, 2H), 6.39 (d, J ¼ 9.0 Hz, 2H), 6.03 (d, J ¼ 9.0 Hz, 2H),
5.17 (brs, 2H), 2.89 (s, 3H); 13C NMR (125 Hz, actone-d6) d: 159.8, 152.7, 137.8,
136.6, 132.8, 132.0, 131.3 (q, J ¼ 33.4 Hz, 1C), 130.2 (2C), 129.6, 128.5, 128.0,
125.3, 122.1 (q, J ¼ 270.5 Hz, 1C), 115.7, 113.8, 93.2, 55.6; LRMS (EI, 70 eV) m=z
(%): 424 (Mþ, 100). HRMS (ESI) for C18H12ClF3N4OS (Mþ) calcd.: 424.0374;
found: 424.0375.
5-Amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-phenylselanyl-
1H-pyrazole-3-carbonitrile (4ai)
1
White oil; H NMR (300 MHz, actone-d6) d: 8.11 (s, 2H), 7.32–7.23 (m, 5H),
6.15 (brs, 2H); 13C NMR (125 MHz, actone-d6) d: 153.4, 137.4 (2C), 137.0, 134.7
(q, J ¼ 33.8 Hz, 1C), 134.0, 132.8, 132.0, 130.3 (2C), 129.2 (2C), 127.3 (2C), 123.3
(q, J ¼ 271.4 Hz, 1C), 113.9, 85.6; LRMS (EI, 70 eV) m=z (%): 476 (Mþ, 100). HRMS
(ESI) for C17H9Cl2F3N4Se (Mþ) calcd.: 475.9322; found: 475.9321.
5-Amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-benylselanyl-
1H-pyrazole-3-carbonitrile (4aj)
1
White solid, mp 153–155 ꢀC (uncorrected); H NMR (300 MHz, actone-d6) d:
8.05 (s, 2H), 7.25–7.19 (m, 5H), 5.64 (brs, 2H), 3.96 (s, 2H); 13C NMR (125 MHz,
actone-d6) d: 153.0, 139.7, 137.4 (2C), 137.2, 134.5 (q, J ¼ 33.8 Hz, 1C), 134.1,
129.9 (2C), 129.3 (2C), 127.7 (2C), 127.4, 123.4 (q, J ¼ 271.3 Hz, 1C), 114.1, 86.0,
32.3; LRMS (EI, 70 eV) m=z (%): 490 (Mþ, 100). HRMS (ESI) for C18H11Cl2F3N4Se
(Mþ) calcd.: 489.9478; found: 489.9477.
5-Amino-1-[2-chloro-4-(trifluoromethyl)phenyl]-4-Phenylselanyl-1H-
pyrazole-3-carbonitrile (4bi)
Yellow solid, mp 139–140 ꢀC (uncorrected); 1H NMR (300 MHz, actone-d6) d:
8.12 (s, 1H), 8.02–7.82 (m, 2H), 7.37–7.26 (m, 5H), 5.96 (brs, 2H); 13C NMR
(125 MHz, actone-d6) d: 153.4, 137.8, 136.6, 133.0, 132.8, 132.7, 131.0 (q, J ¼ 33.5 Hz,
Hz, 1C), 130.3 (2C), 129.6 (2C), 129.5, 128.5 (2C), 125.5 (q, J ¼ 270.3 Hz, 1C), 114.2,

3480
M. XU, X. H. ZHANG, AND P. ZHONG
85.9; LRMS (EI, 70 eV) m=z (%): 442 (Mþ, 100). HRMS (ESI) for C17H10ClF3N4Se
(Mþ) calcd.: 441.9711; found: 441.9710.
5-Amino-1-[2-chloro-4-(trifluoromethyl)phenyl]-4-Benzylselanyl-1H-
pyrazole-3-carbonitrile (4bj)
1
Yellow liquid; H NMR (300MHz, CDCl3) d: 7.75–7.61 (m, 3H), 7.26–7.1 (m,
5H), 3.88 (brs, 2H), 3.69 (s, 2H); 13C NMR (125MHz, CDCl3) d: 150.7, 138.6, 135.7,
135.1, 132.8, 131.6, 130.9 (q, J ¼ 33.7Hz, 1C), 128.9 (2C), 128.5 (2C), 128.3, 127.1,
126.9, 122.7 (q, J ¼ 271.1 Hz, 1C), 112.9, 88.3, 32.5; LRMS (EI, 70eV) m=z (%): 456
(Mþ, 100). HRMS (ESI) for C18H12ClF3N4Se (Mþ) calcd.: 455.9868; found: 455.9871.
5-Amino-1-[2-chloro-5-(trifluoromethyl)phenyl]-4-Phenylselanyl-1H-
pyrazole-3-carbonitrile (4ci)
1
Brown solid; mp 154–155 ꢀC (uncorrected); H NMR (300 MHz, actone-d6) d:
8.13–7.98 (m, 3H), 7.38–7.24 (m, 5H), 5.97 (brs, 2H); 13C NMR (125 MHz,
actone-d6) d: 153.4, 137.8, 136.6, 133.1, 132.8 (2C), 131.0 (q, J ¼ 33.5 Hz, 1C),
130.3 (2C), 129.6 (2C), 129.5, 128.5, 127.4, 124.2 (q, J ¼ 270.1 Hz, 1C), 114.2, 86.0;
LRMS (EI, 70 eV) m=z (%): 442 (Mþ, 100). HRMS (ESI) for C17H10ClF3N4Se
(Mþ) calcd.: 441.9711; found: 441.9713.
5-Amino-1-[2-chloro-5-(trifluoromethyl)phenyl]-4-Benzylselanyl-1H-
pyrazole-3-carbonitrile (4cj)
1
Yellow oil; H NMR (300 MHz, CDCl3) d: 7.75–7.61 (m, 3H), 7.24–7.11 (m,
5H), 4.12 (brs, 2H), 3.7 (s, 2H); 13C NMR (75 MHz, CDCl3) d: 150.7, 138.6,
135.7, 135.1, 132.8, 131.6, 130.8 (q, J ¼ 33.7 Hz, 1C), 128.9 (2C), 128.5 (2C), 128.3,
127.1, 127.0, 122.3 (q, J ¼ 271.1 Hz, 1C), 112.9, 88.3, 32.5, 141.3, 139.4, 135.5,
130.3, 128.8, 125.6, 124.6, 122.2, 120.7, 119.0, 110.8, 99.2, 12.1; LRMS (EI, 70 eV)
m=z (%): 456 (Mþ, 100). HRMS (ESI) for C18H12ClF3N4Se (Mþ) calcd.: 455.9868;
found: 455.9869.
ACKNOWLEDGMENTS
The authors thank the National Natural Science Foundation of China (No.
20972114) and Zhejiang Provincial Natural Science Foundation of China (Y4100578).
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