Design, synthesis, and biological activities of novel pyrazole oxime compounds containing a substituted pyridyl moiety

Article abstract of DOI:10.3390/molecules22060878

In this paper, in order to find novel biologically active pyrazole oximes, a series of pyrazole oxime compounds bearing a substituted pyridyl unit were prepared. Bioassays showed that some target compounds were found to have good acaricidal activity against Tetranychus cinnabarinus at a concentration of 500 μg/mL, compound 9q especially displayed potent acaricidal activity against T. cinnabarinus when the concentration was reduced to 100 μg/mL. Interestingly, most target compounds possessed excellent insecticidal activities against Oriental armyworm at 500 μg/mL. Moreover, some compounds were active against Aphis medicaginis and Nilaparvata lugens at 500 μg/mL. Additionally, compounds 9b, 9g, 9l, 9p, 9q, 9r, 9s, 9t, 9u, and 9v displayed significant antiproliferative activities against HepG2 cells with IC50 values of 1.53-17.27 μM, better than that of the control 5-fluorouracil (IC₅₀ = 35.67 μM).

Full text of DOI:10.3390/molecules22060878

molecules
Article
Design, Synthesis, and Biological Activities of Novel
Pyrazole Oxime Compounds Containing a
Substituted Pyridyl Moiety
Cuili Chen 1,2, Jia Chen 3, Haiying Gu 1,2,*, Ning Bao 2 and Hong Dai 3,
*
1
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123,
China; cleancucumber@163.com
School of Public Health, Nantong University, Nantong 226019, China; ningb2000@yahoo.com
College of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, China;
15642891665@163.com
2
3
*
Correspondence: guhy99@21cn.com (H.G.); daihong_2015@aliyun.com (H.D.);
Tel./Fax: +86-513-8501-2913 (H.G. & H.D.)
Academic Editor: Jean Jacques Vanden Eynde
Received: 16 April 2017; Accepted: 23 May 2017; Published: 25 May 2017
Abstract: In this paper, in order to find novel biologically active pyrazole oximes, a series of pyrazole
oxime compounds bearing a substituted pyridyl unit were prepared. Bioassays showed that some
target compounds were found to have good acaricidal activity against Tetranychus cinnabarinus
at a concentration of 500
µg/mL, compound 9q especially displayed potent acaricidal activity
against T. cinnabarinus when the concentration was reduced to 100
µg/mL. Interestingly, most
target compounds possessed excellent insecticidal activities against Oriental armyworm at 500
Moreover, some compounds were active against Aphis medicaginis and Nilaparvata lugens at 500
µ
g/mL.
g/mL.
µ
Additionally, compounds 9b, 9g, 9l, 9p, 9q, 9r, 9s, 9t, 9u, and 9v displayed significant antiproliferative
activities against HepG2 cells with IC50 values of 1.53–17.27 µM, better than that of the control
5-fluorouracil (IC50 = 35.67 µM).
Keywords: pyrazole oxime; pyridyl; synthesis; biological activity
1. Introduction
In the past few decades, heterocycles play a significant role in the research of agricultural
and medicinal chemistry. Pyrazole oxime is a vital five-membered aromatic heterocycle. A lot of
pyrazole oxime derivatives have drawn considerable attention for their extensive biological activities
including insecticidal [1], acaricidal [2], fungicidal [3], antitumor [4], and antiviral activity [5]. For
example, fenpyroximate (Figure 1), a potent acaricide carrying a pyrazole oxime unit, is used to
control some important phytophagous mites such as Tetranychus urticae Koch and Polyphagotarsonemus
latus Banks [
structural modification of fenpyroximate. Recently, Zou et al. reported that thiazole-containing
pyrazole oxime compound (Figure 1) displayed good insecticidal activity [ ], Dai et al. obtained
pyrazole oxime compound (Figure 1) bearing a benzyloxy-linked thiazole unit exhibiting interesting
insecticidal activity besides good acaricidal activity [ ]. Park et al. reported some Fenpyroximate
analogues possessing potential anticancer properties against HepG2 (human hepatoma) cells [ ],
6]. After it appeared on the market in 1991, many chemists began to study the
A
7
B
8
9
and Dai et al. also found some 1,2,3-thiadiazole-containing pyrazole oxime derivatives displaying
satisfactory antitumor activities against Panc-1 (human pancreatic carcinoma) and SGC-7901 (human
gastric cancer) cells [10]. Therefore, pyrazole oxime compounds became a focus of chemical and
pharmaceutical research.
Molecules 2017, 22, 878; doi:10.3390/molecules22060878
www.mdpi.com/journal/molecules

Molecules 2017, 22, 878
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O
N
N
N
N
N
O
N
N
O
O
S
Cl
N
O
N
O
S
N
Cl
N
O
O
O
Cl
Fenpyroximate
A
B
CN
NO2
N
N
CN
N
N
N
S
NH
N
CH3
Cl
N
Cl
N
CH3
Cl
N
Imidacloprid
Thiacloprid
Acetamiprid
O
O
R1
N
CH2NH
R2
OC2H4OC2H5
Cl
CH2NH
Me2CH
C
OC2H4OC2H5
CN
CN
R1= Cl, MeO, EtO
R2= Me, Et, MeS, CHMe2
D
O
O
CH2NH
R
OC2H4OC2H5
Cl
N
CN
R= Me, Et, MeS, CHMe2
E
Figure 1. Structures of fenpyroximate, imidacloprid, thiacloprid, acetamiprid, and compounds A–E.
On the other hand, the pyridyl ring is another important six-membered aromatic heterocycle
containing one nitrogen atom, which plays a vital role in lots of biologically active compounds [11 14].
Many pyridine-based derivatives are found to possess broad spectrum biological activities such
as fungicidal [15], insecticidal [16 18], herbicidal [19], antiviral [20], and anticancer activities [21].
–
–
For instance, imidacloprid, thiacloprid, and acetamiprid (Figure 1), well-known pyridyl-containing
neonicotinoid insecticides, are currently used in the fields of crop protection and animal health due
to their good insecticidal activities and low mammalian toxicity [22]. Recently, Wang et al. reported
the preparation of novel 2-cyanoacrylates
compound (Figure 1) with a substituted pyridyl group, resulting in better biological activity and
broader bioactivity spectra [23]. More recently, Wu et al. found that some 2-cyanoacrylates (Figure 1)
D (Figure 1) and replaced the substituted phenyl ring of
C
E
carrying a benzyloxy-linked pyridyl unit also indicated wonderful bioactivities [24]. So we have reason
to believe that the substituted pyridyl moiety can be used as a significant skeleton in exploring novel
bioactive molecules.
Motivated by the above viewpoints, we conceived that replacement of the esterified phenyl ring
of fenpyroximate with a substituted pyridine group might produce some new compounds with good
biological activities (Figure 2). In this research, we report the synthesis and bioactivities of novel
pyrazole oximes containing a substituted pyridyl moiety.
Cl
N
S
N
N
O
O
N
R1
N
N
O
O
N
O
O
R2
R1 = Me, 4-MeC6H4
R2 = MeO, Me, F, Cl, Br, I, etc.
Fenpyroximate
Target Molecules
Figure 2. The design of the title molecules.

Molecules 2017, 22, 878
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2. Results and Discussion
2.1. Chemistry
As indicated in Scheme 1, 23 pyrazole oxime compounds carrying substituted pyridine moiety
were successfully prepared. Using potassium hydroxide as the base, compound was easily reacted
with 2-mercaptobenzoic acid or 4-mercaptobenzoic acid to give compound . Further reaction with
methanol, under acidic condition, afforded compound in satisfactory yields. The next reaction
with LiAlH4 produced compound in good yields. Then chlorination of compound provided
the key intermediate successfully. The condensation of compound with different substituted
phenols under basic conditions afforded 5-aryloxy substituted pyrazole carbaldehyde ( ), which was
then transformed to 5-aryloxy substituted pyrazole oximes ( ) by the treatment with hydroxylamine
with oximes , under cesium carbonate
9w in good yields. The title compounds
1
2
3
4
4
5
6
7
8
hydrochloride. Finally, the reaction of the key intermediate
5
8
promoting conditions, provided the designed compounds 9a
–
have all been structurally confirmed through 1H NMR, 13C NMR and elemental analyses.
O
O
b
N
S
OCH3
N
S
OH
a
N
Cl
Cl
Cl
Cl
2a, 2b
3a, 3b
1
d
N
S
Cl
c
N
S
OH
Cl
Cl
5a (-S: 2-position)
5b (-S: 4-position)
4a, 4b
Cl
OH
N
O
N
O
S
H3C
H
H3C
H
H3C
H3C
O
g
R2
R2
f
e
N
O
N
N
R1
N
O
N
N
Cl
O
N
N
N
R2
R1
R1
R1
9a-9k (-S: 2-position)
9l-9w (-S: 4-position)
7
6
8
9i: R1 =Me, R2 =4-I
9a: R1 =Me, R2 =4-OMe
9b: R1 =Me, R2 =4-Me
9c: R1 =Me, R2 =2-F
9q: R1 =Me, R2 =4-F
9r: R1 =Me, R2 =4-Cl
9s: R1 =Me, R2 =4-Br
9j: R1 =Me, R2 =2,4-F2
9k: R1 =Me, R2 =2,4-Cl2
9l: R1 =Me, R2 =4-OMe
9d: R1 =Me, R2 =3-F
9e: R1 =Me, R2 =4-F
9t: R1 =Me, R2 =4-I
9m: R1 =Me, R2 =4-Me
9n: R1 =Me, R2 =4-OCF3
9o: R1 =Me, R2 =2-F
9p: R1 =Me, R2 =3-F
9u: R1 =Me, R2 =2,4-F2
9v: R1 =Me, R2 =2,4-Cl2
9f: R1 =Me, R2 =2-Cl
9g: R1 =Me, R2 =4-Cl
9w: R1 =4-MeC6H4, R2 =4-Me
9h: R1 =Me, R2 =4-Br
Scheme 1. Synthesis of the target compounds 9a–9w. Reagents and conditions: (a) 2-mercaptobenzoic
acid or 4-mercaptobenzoic acid, potassium hydroxide, ethanol, reflux for 10 h, 65% for 2a, 70%
for 2b; (b) methanol, concentrated sulfuric acid, reflux for 8 h, 75% for 3a, 83% for 3b; (c) LiAlH4,
tetrahydrofuran, 0◦◦C for 10 min, r.t. for 2 h, 63% for 4a, 71% for 4b; (d) thionyl chloride,
dichloromethane, 0 C for 10 min, r.t. for 3 h, 73% for 5a, 80% for 5b; (e) substituted phenols, potassium
◦
◦
hydroxide, DMF, 40 C for 6 h, then 100 C for 12–20 h, 58–80% for
7; (f) hydroxylamine hydrochloride,
potassium hydroxide, methanol, reflux for 8–15 h, 56–77% for ; (g) compounds
8
5
, potassium carbonate,
cesium carbonate, acetonitrile, reflux for 8–17 h, 53–75% for 9.
2.2. Biological Activities
2.2.1. Acaricidal Activities and Insecticidal Activity
The synthesized compounds 9a
–9w were tested for acaricidal activity against Tetranychus
cinnabarinus and insecticidal activities against Oriental armyworm, Aphis medicaginis and

Molecules 2017, 22, 878
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Nilaparvata lugens. Abamectin and Fenpyroximate were used as the positive controls, respectively.
As displayed in Table 1, some of the target compounds showed good acaricidal activity against
T. cinnabarinus at a concentration of 500
compounds 9m 9p, and 9q were 80.65%, 80.56%, and 80.78%, respectively, which were similar
to that of the control Fenpyroximate. When the dosage was reduced to 100 g/mL, compound 9q was
µg/mL. Among these compounds, the mortalities of
,
µ
still active against T. cinnabarinus with inhibitory value of 70.89%. Besides acaricidal activity, most of
the aimed compounds demonstrated excellent insecticidal activities against Oriental armyworm at a
concentration of 500
µg/mL (Table 2), for instance, compounds 9a, 9c, 9d, 9e, 9f, 9g, 9h, 9i, 9j, 9k, 9l, 9m,
9n 9o 9q 9r 9s 9t, and 9u all had over 90.00% inhibition rates, which were comparable to that of the
,
,
,
,
,
control Abamectin (100.00%). As shown in Table 2, some title compounds indicated good insecticidal
activities against A. medicaginis at a concentration of 500 µg/mL, for example, compounds 9l, 9m, 9p,
9q, 9r, 9s, 9t, and 9u all possessed 100.00% inhibition rates, which were equally to that of the control
Abamectin. Interestingly, some designed compounds showed potent insecticidal activity against
N. lugens and beyond good insecticidal activities against A. medicaginis. Among these compounds,
compounds 9l, 9m, 9o, 9p, 9q, 9r, 9s, and 9u had a >80.00% inhibition rate at 500 µg/mL. Based on
the structure-activity data, we found that when the mercapto group is at the 4-position and R1 is Me,
the substituent R2 at the 4-position of the phenyl ring was methoxy (9l), methyl (9m), fluoro (9q) or
chloro group (9r) or the substituent R2 at the 3-position of phenyl ring was fluoro atom (9p), it was
advantageous to increase the biological activity spectrum.
Table 1. Acaricidal activities of compounds 9a–9w (mortality, %).
Tetranychus cinnabarinus
Compd.
500 µg/mL
100 µg/mL
20 µg/mL
b
9a
0
—
—
9b
9c
0
0
—
—
—
—
9d
9e
0
0
—
—
—
—
9f
9g
0
0
—
—
—
—
9h
9i
0
0
—
—
—
—
9j
9k
9l
9m
0
0
—
—
—
0
—
—
—
—
50.39 ± 0.83 a
80.65 ± 1.32
9n
0
—
—
9o
9p
9q
9r
0
—
0
—
—
80.56 ± 1.05
80.78 ± 0.76
70.89 ± 1.13
30.55 ± 0.35
40.92 ± 1.68
—
—
9s
0
—
—
9t
9u
0
0
—
—
—
—
9v
9w
0
0
—
—
—
—
Fenpyroximate
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
Each value represents the mean ± standard error of three replications; b “—” refers to “not tested”.
a

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Table 2. Insecticidal activities of compounds 9a–9w (mortality, %).
Oriental armyworm
500 µg/mL 100 µg/mL
Aphis medicaginis
500 µg/mL 100 µg/mL
Nilaparvata lugens
500 µg/mL 100 µg/mL
Compd.
9a
9b
9c
9d
9e
9f
9g
9h
9i
9j
9k
9l
9m
9n
9o
9p
9q
9r
9s
9t
9u
9v
9w
100.00 ± 0.00 a
80.23 ± 1.22
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
90.36 ± 1.35
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
60.45 ± 0.82
90.56 ± 1.91
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
100.00 ± 0.00
80.33 ± 0.79
80.25 ± 1.22
100.00 ± 0.00
0
0
0
0
0
—
—
—
—
—
—
—
—
0
0
0
—
0
0
0
0
0
0
0
0
0
0
—
—
0
70.57 ± 1.26
20.41 ± 1.02
0
—
—
—
—
—
—
—
0
0
—
0
0
0
0
0
—
0
—
—
0
0
0
0
0
0
0
0
0
0
50.68 ± 1.72
60.36 ± 0.96
0
0
0
0
—
—
—
100.00
100.00
±
0.00
0.00
20.88 ± 1.52
100.00
100.00
±
0.00
0.00
±
0
—
—
0
±
0
0
0
95.54 ± 1.62
b
100.00
±
±
±
±
±
±
0.00
0.00
0.00
0.00
0.00
0.00
100.00
100.00
±
±
0.00
0.00
—
0
100.00
100.00
100.00
100.00
100.00
0
0
0
0
0
—
—
30.62 ± 0.87
90.66 ± 1.08
0
100.00
±
0.00
40.37 ± 1.18
60.53 ± 1.37
0
0
0
80.68 ± 0.29
50.77 ± 0.42
0
0
0
Abamectin
100.00
±
0.00 100.00
±
0.00 100.00
±
0.00 100.00
±
0.00 100.00
±
0.00
Each value represents the mean ± standard error of three replications; b “—” refers to “not tested”.
a
2.2.2. Anticancer Activities
The inhibitory activity of the target compounds 9a
–
9w against human pancreatic carcinoma cells
(Panc-1), human hepatoma cells (HepG2), and human gastric cancer cells (SGC-7901) were screened
and evaluated in vitro by the MTT method using sorafenib and 5-fluorouracil as positive controls,
respectively. Their IC50 values were presented in Table 3. As can be seen, some title compounds
showed more potent antiproliferative activity on HepG2 cells than Panc-1 and SGC-7901 cells. Among
these compounds, compounds 9b
activities against HepG2 cells with IC50 values of 1.53–17.27
5-fluorouracil (IC50 = 35.67 M). Especially, the inhibitory effect of compound 9r, against HepG2 cell,
,
9g
,
9l
,
9p
,
9q
,
9r
,
9s
,
9t
,
9u, and 9v indicated good antiproliferative
µM, better than that of the control
µ
was 23-fold as strong as that of 5-fluorouracil. Based on the structure-antitumor activity data, we found
that when the mercapto group is at the 4-position and R1 is Me, the 3-fluoro substituted compound 9p
and 4-chloro substituted compound 9r exhibited more potent inhibitory activity against HepG2 cell.
All the above results implied that good biological activities can be achieved through introducing
substituted pyridyl moiety into pyrazole oxime unit. To obtain more active derivatives, further studies
on these compounds are well under way.
Table 3. Antiproliferative activity of compounds 9a–9w.
IC50, µM
Compd.
Panc-1
HepG2
SGC-7901
9a
9b
9c
9d
9e
9f
9g
9h
9i
>40
>40
>40
>40
>40
>40
>40
>40
>40
>40
>40
>40
12.65 ± 0.75
>40
>40
>40
>40
>40
>40
>40
>40
>40
>40
>40
>40
39.35 ± 0.60
>40
39.52 ± 0.51
17.27 ± 2.02
39.02 ± 0.93
>40
9j
9k
>40
>40

Molecules 2017, 22, 878
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Table 3. Cont.
IC50, µM
Compd.
Panc-1
HepG2
SGC-7901
9l
9m
>40
>40
8.72 ± 1.23
>40
>40
>40
9n
9o
>40
>40
33.46 ± 2.55
>40
>40
>40
9p
9q
9r
9s
9t
9u
9v
>40
>40
>40
>40
>40
>40
>40
>40
7.24 ± 0.54
8.27 ± 1.47
1.53 ± 0.79
9.76 ± 2.32
9.13 ± 1.73
15.24 ± 3.05
11.93 ± 2.24
>40
>40
>40
>40
>40
>40
>40
>40
>40
9w
Sorafenib
5-Fluorouracil
11.50 ± 2.32
—
12.10 ± 2.68
—
35.67 ± 3.15
—
“—” refers to not tested.
3. Experimental Section
3.1. Chemistry
3.1.1. General Procedures
All reagents are commercially available and used without further purification except as indicated.
The melting points were determined on an X-4 binocular microscope melting point apparatus
1
(Beijing Tech Instrument Co., Beijing, China) and are uncorrected. H NMR and 13C NMR spectra
1
were measured on a Bruker AV400 spectrometer (400 MHz, H; 100 MHz, 13C, Bruker, Billerica,
MA, USA) in CDCl3 with TMS as an internal standard. Elemental analyses were determined
on a Yanaco CHN Corder MT-3 elemental analyzer (Yanaco, Kyoto, Japan). The intermediate
1-methyl-3-methyl-5-chloro-1H-pyrazole-4-carbaldehyde (6) was prepared according to the reported
procedures [25].
3.1.2. Synthesis of Compound 2
To a solution of 2 (or 4)-mercaptobenzoic acid (3.1 g, 20 mmol), compound
1 (3.3 g, 22 mmol) and
anhydrous ethanol (100 mL) was added potassium hydroxide (2.2 g, 40 mmol) at room temperature.
The resulting mixture was heated to reflux for 10 h. Then it was cooled to room temperature, allowed to
settle for 2 h, and the precipitates were collected by filtration. To the solid was added 100 mL of water,
followed by adding 5% hydrochloric acid to adjust the pH to 2–3. The precipitates were filtered off to
obtain compound
13.11 (s, 1H, COOH); 8.47 (d, J = 2.4 Hz, 1H, Py-H); 7.22–7.92 (m, 6H, Py-H and Ar-H); 4.27 (s, 2H,
CH2). Compound 2b: white solid; yield 70%; m.p. 180–182 ◦C. 1H NMR (DMSO-d6):
12.95 (s, 1H,
2
. Compound 2a: white solid; yield 65%; m.p. 218–219 ◦C. 1H NMR (DMSO-d6):
δ
δ
COOH); 8.43 (d, J = 2.4 Hz, 1H, Py-H); 7.43–7.90 (m, 6H, Py-H and Ar-H), 4.40 (s, 2H, CH2).
3.1.3. Synthesis of Compound 3
To a solution of compound
2 (5.6 g, 20 mmol) in anhydrous methanol (60 mL) was added
concentrated sulfuric acid (2 mL) at room temperature. The resulting mixture was heated to reflux for
8 h and cooled to room temperature, allowed to settle for 1 h, and the precipitates were obtained by
◦
3
. Compound 3a: white solid; yield 75%; m.p. 79–80 C. 1H NMR (CDCl3):
filtration to give compound
8.16 (d, J = 2.4 Hz, 1H, Py-H); 7.97 (d, J = 7.6 Hz, 1H, Ar-H); 7.66 (dd, J1 = 2.4 Hz, J2 = 8.4 Hz, 1H,
δ
Py-H); 6.70–7.46 (m, 4H, Py-H◦and Ar-H); 4.09 (s, 2H, CH2); 3.93 (s, 3H, OCH3). Compound 3b: white
solid; yield 83%; m.p. 101–102 C. 1H NMR (CDCl3):
δ 8.24 (d, J = 2.0 Hz, 1H, Py-H); 7.85 (d, J = 8.4 Hz,
1H, Ar-H); 7.54 (dd, J1 = 2.0 Hz, J2 = 8.0 Hz, 1H, Py-H); 7.18–7.21 (m, 3H, Py-H and Ar-H); 4.07 (s, 2H,
CH2), 3.83 (s, 3H, OCH3).

Molecules 2017, 22, 878
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3.1.4. Synthesis of Compound 4
A solution of intermediate
3
(5.9 g, 20 mmol) in anhydrous tetrahydrofuran (60 mL) was cooled in
an ice-water bath followed by adding lithium aluminum hydride (1.1 g, 40 mmol) in portions. Then the
resulting mixture was stirred at room temperature for 2 h. The reaction mixture was poured into water
(80 mL). The precipitates were filtered off, and the filtrate was continuously extracted with ethyl acetate
(3
Na2SO4, and concentrated in a rotatory evaporator to afford compound
yield 63%; m.p. 80–81 ◦C. 1H NMR (CDCl3):
8.14 (d, J = 2.0 Hz, 1H, Py-H); 7.50 (dd, J1 = 2.4 Hz,
×
50 mL). The combined organic layer was washed by water and brine, dried over anhydrous
4. Compound 4a: white solid;
δ
J2 = 8.0 Hz, 1H, Py-H); 7.21–7.43 (m, 5H, Py-H and Ar-H); 4.70 (s, 2H, CH2); 4.02 (s, 2H, CH2). Anal.
Calcd. for C13H12ClNOS: C 58.75; H 4.55; N 5.27. Found: C 58.88; H 4.63; N 5.16. Compound 4b: white
◦
solid; yield 71%; m.p. 73–74 C. 1H NMR (CDCl3):
δ 8.12 (d, J = 2.4 Hz, 1H, Py-H); 7.56 (dd, J1 = 2.8 Hz,
J2 = 8.0 Hz, 1H, Py-H); 7.22–7.27 (m, 5H, Py-H and Ar-H); 4.66 (s, 2H, CH2); 4.01 (s, 2H, CH2). Anal.
Calcd. for C13H12ClNOS: C 58.75; H 4.55; N 5.27. Found: C 58.63; H 4.66; N 5.39.
3.1.5. Synthesis of Compound 5
A solution of intermediate
4 (5.3 g, 20 mmol) in dichloromethane (30 mL) was cooled in ice-water
bath followed by adding dropwise a mixture of thionyl chloride (8.9 g, 40 mmol) and dichloromethane
(20 mL). The reaction mixture was stirred at room temperature for 3 h. The reaction mixture was
quenched by trash ice, then the organic phase was separated, washed by water and saturated
NaCl solution, dried over anhydrous Na2SO4, and evaporated in vacuo to produce compound
5
.
1
Compound 5a: yellow oil; yield 73%. H NMR (CDCl3):
δ 8.15 (d, J = 2.4 Hz, 1H, Py-H); 7.22–7.53
(m, 6H, Py-H and Ar-H); 4.72 (s, 2H, CH2); 4.06 (s, 2H, CH2). Anal. Calcd. for C13H11Cl2NS: C 54.94;
H 3.90; N 4.93. Found: C 55.07; H 3.79; N 4.81. Compound 5b: white solid; yield 80%; m.p. 70–71 ◦C.
1H NMR (CDCl3):
δ 8.21 (d, J = 2.8 Hz, 1H, Py-H); 7.25–7.58 (m, 6H, Py-H and Ar-H); 4.54 (s, 2H, CH2);
4.04 (s, 2H, CH2). Anal. Calcd. for C13H11Cl2NS: C 54.94; H 3.90; N 4.93. Found: C 54.81; H 3.99;
N 5.05.
3.1.6. General Procedure for the Preparation of 7a–7w
To a solution of substituted phenol (75 mmol) in N,N-dimethylformamide (60 mL) was add◦ed
potassium hydroxide (100 mmol) at room temperature. The reaction mixture was heated to 40 C
for 6 h. Then to the above mixture was added compound
mixture was heated to 100 ◦C for 12–20 h. The reaction solution was poured into water (100 mL) and
was continuously extracted with ethyl acetate (3 50 mL). The combined organic layer was washed
6 (50 mmol) in portions, and the resulting
×
by water and brine, dried over anhydrous Na2SO4, and concentrated in rotatory evaporator to give
compounds 7a–7w, with yields ranging from 58% to 80% [26].
3.1.7. General Procedure for the Preparation of 8a–8w
To a well stirred solution of hydroxylamine hydrochloride (45 mmol) and potassium hydroxide
(45 mmol) in methanol (60 mL) was added compound
7 (30 mmol) at room temperature. The reaction
mixture was heated to reflux for 8–15 h and cooled to room temperature. The reaction solution was
poured into water (100 mL). The resulting precipitate was collected by filtration and washed with
water to afford compounds 8a–8w, with yields ranging from 56% to 77% [26].
3.1.8. General Procedure for the Preparation of 9a–9w
To a well stirred solution of intermediate
5 (6 mmol), compound 8 (5 mmol), and powdered
potassium carbonate (12 mmol) in anhydrous acetonitrile (25 mL) was added Cs2CO3 (1 mmol) at
room temperature, the resulting mixture was heated to reflux for 8–17 h. After cooled to room
temperature, the reaction mixture was filtered. After the solvent had been removed under reduced
pressure, the residue was admixed with water (80 mL) and extracted with ethyl acetate (3 × 50 mL).

Molecules 2017, 22, 878
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The combined organic layer was dried over anhydrous Na2SO4. The solvent was evaporated in
vacuo, and the residue was then subjected to column chromatography using a mixture of petroleum
ether and ethyl acetate as an eluent to produce the title compounds 9a
–
9w, with yields ranging from
53% to 75%. All 23 pyrazole oxime derivatives 9a
–9w were novel and the physical and spectral
data for these compounds are listed below. 1H NMR and 13C NMR spectra are provided in the
Supplementary Materials.
1-Methyl-3-methyl-5-(4-methoxyphenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9a). Yellow oil, yield 62%. H NMR (CDCl3):
δ 8.02 (s, 1H, Py-H), 7.70 (s, 1H,
CH=N), 7.38 (d, J = 8.0 Hz, 1H, Py-H), 7.27 (d, J = 6.4 Hz, 1H, Py-H), 7.09–7.18 (m, 4H, Ar-H), 6.73 (s,
4H, Ar-H), 5.05 (s, 2H, CH2), 3.88 (s, 2H, CH2), 3.68 (s, 3H, OCH3), 3.52 (s, 3H, N-CH3), 2.27 (s, 3H,
CH3); 13C NMR (CDCl3):
δ 155.8, 150.7, 150.1, 149.6, 148.5, 146.9, 141.0, 139.4, 139.1, 133.6, 132.9, 132.6,
130.6, 128.6, 127.9, 123.9, 116.4, 114.9, 99.8, 74.1, 55.7, 36.2, 34.2, 14.9. Anal. Calcd. for C26H25ClN4O3S:
C 61.35; H 4.95; N 11.01. Found: C 61.48; H 4.86; N 11.13.
1-Methyl-3-methyl-5-(4-methylphenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9b). White oil, yield 60%. H NMR (CDCl3):
δ 8.09 (d, J = 2.0 Hz, 1H, Py-H),
7.78 (s, 1H, CH=N), 7.33–7.46 (m, 2H, Py-H and Ar-H), 7.16–7.26 (m, 4H, Ar-H and Py-H), 7.06 (d,
J = 8.4 Hz, 2H, Ar-H), 6.76 (d, J = 8.4 Hz, 2H, Ar-H), 5.12 (s, 2H, CH2), 3.95 (s, 2H, CH2), 3.57 (s, 3H,
N-CH3), 2.35 (s, 3H, CH3), 2.28 (s, 3H, CH3); 13C NMR (CDCl3):
δ 154.7, 150.1, 149.6, 148.2, 146.8, 140.9,
139.2, 139.1, 133.6, 133.2, 132.8, 132.6, 130.6, 130.4, 128.6, 127.9, 123.9, 115.1, 100.0, 74.1, 36.2, 34.2, 20.6,
14.9 Anal. Calcd. for C26H25ClN4O2S: C 63.34; H 5.11; N 11.36. Found: C 63.22; H 5.23; N 11.47.
1-Methyl-3-methyl-5-(2-fluorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9c). Yellow oil, yield 53%. H NMR (CDCl3):
δ 8.10 (d, J = 2.4 Hz, 1H, Py-H), 7.79
(s, 1H, CH=N), 7.44–7.47 (m, 1H, Py-H), 7.12–7.32 (m, 6H, Ar-H and Py-H), 6.96–7.05 (m, 2H, Ar-H),
6.73–6.77 (m, 1H, Ar-H), 5.08 (s, 2H, CH2), 3.96 (s, 2H, CH2), 3.64 (s, 3H, N-CH3), 2.32 (s, 3H, CH3);
13C NMR (CDCl3):
δ 151.6 (d, J = 247 Hz), 150.1, 149.6, 147.3, 146.9, 144.2, 140.4, 139.1, 139.0, 133.6,
132.7, 132.5, 130.5, 128.7, 127.8, 124.6, 124.0, 117.1 (d, J = 17 Hz), 116.7, 99.8, 74.1, 36.1, 34.2, 14.6. Anal.
Calcd. for C25H22ClFN4O2S: C 60.42; H 4.46; N 11.27. Found: C 60.29; H 4.55; N 11.14.
1-Methyl-3-methyl-5-(3-fluorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9d). Yellow oil, yield 55%. H NMR (CDCl3):
δ 8.03 (d, J = 2.0 Hz, 1H, Py-H),
7.73 (s, 1H, CH=N), 7.37–7.40 (m, 1H, Py-H), 7.10–7.24 (m, 6H, Ar-H and Py-H), 6.54–6.74 (m, 3H,
Ar-H), 5.02 (s, 2H, CH2), 3.89 (s, 2H, CH2), 3.52 (s, 3H, N-CH3), 2.28 (s, 3H, CH3); 13C NMR (CDCl3):
δ
163.5 (d, J = 246 Hz), 157.5, 150.1, 149.6, 147.0, 140.5, 139.1, 139.0, 133.7, 132.6, 130.9, 130.8, 130.5,
128.7, 127.8, 124.0, 110.6 (d, J = 29 Hz), 113.4, 103.4 (d, J = 26 Hz), 100.3, 74.1, 36.1, 34.3, 14.7. Anal.
Calcd. for C25H22ClFN4O2S: C 60.42; H 4.46; N 11.27. Found: C 60.53; H 4.34; N 11.20.
1-Methyl-3-methyl-5-(4-fluorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9e). Yellow oil, yield 58%. H NMR (CDCl3):
δ 8.12 (d, J = 2.4 Hz, 1H, Py-H), 7.80
(s, 1H, CH=N), 7.47–7.50 (m, 1H, Py-H), 7.20–7.33 (m, 5H, Py-H and Ar-H), 6.83–7.00 (m, 4H, Ar-H),
5.10 (s, 2H, CH2), 3.98 (s, 2H, CH2), 3.62 (s, 3H, N-CH3), 2.36 (s, 3H, CH3); 13C NMR (CDCl3):
δ
158.7
(d, J = 241 Hz), 152.6, 150.2, 149.6, 147.8, 147.0, 141.6, 140.6, 139.1, 133.7, 132.7, 130.4, 128.7, 127.8, 124.0,
116.4 (d, J = 31 Hz), 74.1, 36.2, 34.2, 14.6. Anal. Calcd. for C25H22ClFN4O2S: C 60.42; H 4.46; N 11.27.
Found: C 60.31; H 4.37; N 11.39.
1-Methyl-3-methyl-5-(2-chlorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9f). Yellow oil, yield 54%. H NMR (CDCl3):
δ 8.10 (d, J = 2.4 Hz, 1H, Py-H), 7.77
(s, 1H, CH=N), 7.41–7.47 (m, 2H, Py-H and Ar-H), 7.17–7.31 (m, 5H, Ar-H and Py-H), 7.10–7.14 (m, 1H,
Ar-H), 7.00–7.04 (m, 1H, Ar-H), 6.65–6.68 (m, 1H, Ar-H), 5.08 (s, 2H, CH2), 3.96 (s, 2H, CH2), 3.62 (s,
3H, N-CH3), 2.34 (s, 3H, CH3); 13C NMR (CDCl3):
δ 152.1, 150.1, 149.6, 147.2, 147.0, 140.4, 139.1, 133.6,
132.7, 132.5, 130.9, 130.5, 128.7, 128.0, 127.8, 124.5, 124.0, 122.7, 115.5, 100.1, 74.2, 36.1, 34.2, 14.6. Anal.
Calcd. for C25H22Cl2N4O2S: C 58.48; H 4.32; N 10.91. Found: C 58.60; H 4.21; N 10.83.

Molecules 2017, 22, 878
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1-Methyl-3-methyl-5-(4-chlorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
◦
phenylmethyl]-oxime (9g). White solid, yield 60%, m.p. 75–77 C. 1H NMR (CDCl3):
δ 8.09 (d, J = 2.4 Hz,
1H, Py-H), 7.78 (s, 1H, CH=N), 7.45–7.48 (m, 1H, Py-H), 7.17–7.29 (m, 7H, Ar-H and Py-H), 6.81 (d,
J = 8.8 Hz, 2H, Ar-H), 5.08 (s, 2H, CH2), 3.96 (s, 2H, CH2), 3.59 (s, 3H, N-CH3), 2.34 (s, 3H, CH3);
13C NMR (CDCl3):
δ 155.2, 150.1, 149.6, 147.1, 147.0, 140.5, 139.1, 139.0, 133.6, 132.6, 132.5, 130.5, 129.9,
128.7, 127.8, 124.0, 116.6, 100.1, 74.1, 36.1, 34.2, 14.6. Anal. Calcd. for C25H22Cl2N4O2S: C 58.48; H 4.32;
N 10.91. Found: C 58.35; H 4.42; N 11.03.
1-Methyl-3-methyl-5-(4-bromophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9h). Yellow oil, yield 59%. H NMR (CDCl3):
δ 8.09 (d, J = 2.0 Hz, 1H, Py-H), 7.78
(s, 1H, CH=N), 7.45–7.48 (m, 1H, Py-H), 7.38 (d, J = 8.8 Hz, 2H, Ar-H), 7.18–7.27 (m, 5H, Ar-H and
Py-H), 6.76 (d, J = 8.8 Hz, 2H, Ar-H), 5.08 (s, 2H, CH2), 3.96 (s, 2H, CH2), 3.59 (s, 3H, N-CH3), 2.34 (s,
3H, CH3); 13C NMR (CDCl3):
δ 155.7, 150.1, 149.6, 147.0, 140.5, 139.1, 133.6, 132.8, 132.6, 132.5, 130.5,
128.7, 127.8, 124.0, 117.1, 116.1, 100.2, 74.2, 36.1, 34.2, 14.5. Anal. Calcd. for C25H22BrClN4O2S: C 53.82;
H 3.97; N 10.04. Found: C 53.69; H 4.08; N 10.14.
1-Methyl-3-methyl-5-(4-iodophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9i). Yellow oil, yield 60%. H NMR (CDCl3):
δ 8.02 (d, J = 2.4 Hz, 1H, Py-H),
7.71 (s, 1H, CH=N), 7.49 (d, J = 8.8 Hz, 2H, Ar-H), 7.38–7.41 (m, 1H, Py-H), 7.11–7.19 (m, 5H, Py-H
and Ar-H), 6.57 (d, J = 8.8 Hz, 2H, Ar-H), 5.00 (s, 2H, CH2), 3.89 (s, 2H, CH2), 3.51 (s, 3H, N-CH3),
2.26 (s, 3H, CH3); 13C NMR (CDCl3): δ 155.6, 149.1, 148.6, 146.0, 139.4, 138.1, 138.0, 137.8, 132.6, 131.7,
131.5, 129.4, 127.7, 126.8, 123.0, 116.6, 99.2, 85.4, 73.2, 35.2, 33.2, 13.5. Anal. Calcd. for C25H22ClIN4O2S:
C 49.64; H 3.67; N 9.26. Found: C 49.78; H 3.56; N 9.38.
1-Methyl-3-methyl-5-(2,4-difluorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9j). Yellow oil, yield 56%. H NMR (CDCl3):
δ 8.10 (d, J = 2.0 Hz, 1H, Py-H), 7.78
(s, 1H, CH=N), 7.46–7.49 (m, 1H, Py-H), 7.19–7.30 (m, 5H, Ar-H and Py-H), 6.88–6.93 (m, 1H, Ar-H),
6.70–6.75 (m, 2H, Ar-H), 5.06 (s, 2H, CH2), 3.97 (s, 2H, CH2), 3.65 (s, 3H, N-CH3), 2.32 (s, 3H, CH3);
13C NMR (CDCl3):
δ 148.6 (d, J = 332 Hz), 148.3 (d, J = 308 Hz), 141.2, 140.2, 139.1, 138.9, 133.6, 132.5,
131.1, 130.3, 128.7, 128.5, 127.8, 124.0, 117.5, 111.0 (d, J = 23 Hz), 105.6 (d, J = 22 Hz), 105.4 (d, J = 22 Hz),
99.5, 74.1, 36.1, 34.2, 14.4. Anal. Calcd. for C25H21ClF2N4O2S: C 58.31; H 4.11; N 10.88. Found: C 58.45;
H 4.04; N 10.76.
1-Methyl-3-methyl-5-(2,4-dichlorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[2-(2-chloropyridin-5-yl-methylthio)
phenylmethyl]-oxime (9k). Yellow oil, yield 57%.1H NMR (CDCl3):
δ 8.10 (d, J = 2.4 Hz, 1H, Py-H),
7.78 (s, 1H, CH=N), 7.41–7.48 (m, 2H, Ar-H and Py-H), 7.05–7.26 (m, 6H, Ar-H and Py-H), 6.59 (d,
J = 8.8 Hz, 1H, Ar-H), 5.05 (s, 2H, CH2), 3.97 (s, 2H, CH2), 3.63 (s, 3H, N-CH3), 2.32 (s, 3H, CH3);
13C NMR (CDCl3):
δ 150.8, 150.1, 149.6, 147.1, 146.5, 140.1, 139.1, 138.9, 133.6, 132.5, 130.5, 130.3, 129.0,
128.7, 127.9, 127.8, 124.0, 123.6, 116.3, 100.1, 74.2, 36.1, 34.3, 14.3. Anal. Calcd. for C25H21Cl3N4O2S:
C 54.80; H 3.86; N 10.23. Found: C 54.93; H 3.76; N 10.12.
1-Methyl-3-methyl-5-(4-methoxyphenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9l). Yellow oil, yield 75%. H NMR (CDCl3):
δ 8.19 (d, J = 2.4 Hz, 1H, Py-H), 7.78
(s, 1H, CH=N), 7.52–7.54 (m, 1H, Py-H), 7.19–7.27 (m, 5H, Py-H and Ar-H), 6.82 (s, 4H, Ar-H), 4.95
(s, 2H, CH2), 4.02 (s, 2H, CH2), 3.78 (s, 3H, OCH3), 3.59 (s, 3H, N-CH3), 2.34 (s, 3H, CH3); 13C NMR
(CDCl3):
δ 155.7, 150.6, 150.2, 149.6, 148.4, 146.8, 141.0, 139.0, 137.0, 133.8, 132.6, 131.5, 130.8, 129.3,
124.1, 116.3, 114.9, 99.8, 75.3, 55.7, 35.8, 34.2, 14.8. Anal. Calcd. for C26H25ClN4O3S: C 61.35; H 4.95;
N 11.01. Found: C 61.23; H 4.85; N 11.10.
1-Methyl-3-methyl-5-(4-methylphenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9m). Yellow oil, yield 73%. H NMR (CDCl3):
δ 8.21 (d, J = 2.4 Hz, 1H, Py-H), 7.81
(s, 1H, CH=N), 7.53–7.56 (m, 1H, Py-H), 7.21–7.24 (m, 5H, Py-H and Ar-H), 7.11 (d, J = 8.4 Hz, 2H,
Ar-H), 6.78 (d, J = 8.4 Hz, 2H, Ar-H), 4.97 (s, 2H, CH2), 4.03 (s, 2H, CH2), 3.60 (s, 3H, N-CH3), 2.37 (s,
3H, CH3), 2.33 (s, 3H, CH3); 13C NMR (CDCl3):
δ 154.7, 150.2, 149.6, 148.1, 146.8, 141.0, 139.0, 137.1,

Molecules 2017, 22, 878
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133.8, 133.2, 132.6, 130.9, 130.4, 129.2, 124.1, 115.1, 100.1, 75.4, 35.9, 34.2, 20.6, 14.9. Anal. Calcd. for
C26H25ClN4O2S: C 63.34; H 5.11; N 11.36. Found: C 63.26; H 5.20; N 11.24.
1-Methyl-3-methyl-5-(4-trifluoromethoxyphenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-
1
methylthio)phenylmethyl]-oxime (9n). Yellow oil, yield 68%. H NMR (CDCl3):
δ 8.19 (s, 1H, Py-H), 7.80
(s, 1H, CH=N), 7.55 (d, J = 6.8 Hz, 1H, Py-H), 7.15–7.23 (m, 7H, Py-H and Ar-H), 6.88 (d, J = 8.8 Hz, 2H,
Ar-H), 4.90 (s, 2H, CH2), 4.02 (s, 2H, CH2), 3.61 (s, 3H, N-CH3), 2.34 (s, 3H, CH3); 13C NMR (CDCl3):
δ 154.8, 150.2, 149.5, 147.2, 146.9, 144.9, 140.2, 139.1, 136.7, 134.0, 132.6, 130.8, 129.2, 124.2, 122.9, 116.5,
100.4, 75.5, 35.7, 34.3, 14.4. Anal. Calcd. for C26H22ClF3N4O3S: C 55.47; H 3.94; N 9.95. Found: C 55.60;
H 3.82; N 9.84.
1-Methyl-3-methyl-5-(2-fluorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
◦
phenylmethyl]-oxime (9o). Yellow solid, yield 61%, m.p. 58–60 C. 1H NMR (CDCl3):
δ 8.19 (d, J = 2.4 Hz,
1H, Py-H), 7.79 (s, 1H, CH=N), 7.52–7.55 (m, 1H, Py-H), 7.14–7.23 (m, 6H, Py-H and Ar-H), 6.98–7.08
(m, 2H, Ar-H), 6.72–6.77 (m, 1H, Ar-H), 4.91 (s, 2H, CH2), 4.02 (s, 2H, CH2), 3.65 (s, 3H, N-CH3), 2.33 (s,
3H, CH3); 13C NMR (CDCl3):
δ 152.0 (d, J = 247 Hz), 150.2, 149.6, 147.3, 147.0, 144.3, 140.4, 139.0, 137.0,
133.9, 132.6, 130.9, 129.2, 124.5, 124.1, 117.1 (d, J = 14 Hz), 116.8, 99.9, 75.4, 35.9, 34.2, 14.5. Anal. Calcd.
for C25H22ClFN4O2S: C 60.42; H 4.46; N 11.27. Found: C 60.51; H 4.34; N 11.40.
1-Methyl-3-methyl-5-(3-fluorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9p). Yellow oil, yield 64%. H NMR (CDCl3):
δ 8.19 (d, J = 2.4 Hz, 1H, Py-H),
7.81 (s, 1H, CH=N), 7.53–7.55 (m, 1H, Py-H), 7.16–7.23 (m, 6H, Py-H and Ar-H), 6.60–6.83 (m, 3H,
Ar-H), 4.93 (s, 2H, CH2), 4.02 (s, 2H, CH2), 3.60 (s, 3H, N-CH3), 2.35 (s, 3H, CH3); 13C NMR (CDCl3):
δ
163.6 (d, J = 248 Hz), 157.6, 150.6, 150.2, 149.6, 147.0, 141.9, 140.9, 140.5, 139.0, 136.9, 133.9, 132.6,
130.8, 129.2, 128.9, 124.1, 110.6 (d, J = 22 Hz), 103.5 (d, J = 21 Hz), 100.3, 75.4, 35.8, 34.2, 14.6. Anal.
Calcd. for C25H22ClFN4O2S: C 60.42; H 4.46; N 11.27. Found: C 60.33; H 4.53; N 11.17.
1-Methyl-3-methyl-5-(4-fluorophenoxy)-1H-pyrazole-4-carbalde◦hyde-O-[4-(2-chloropyridin-5-yl-methylthio)
δ 8.19 (d, J = 2.4 Hz,
phenylmethyl]-oxime (9q). White solid, yield 66%, m.p. 39–41 C. 1H NMR (CDCl3):
1H, Py-H), 7.79 (s, 1H, CH=N), 7.53–7.56 (m, 1H, Py-H), 7.16–7.23 (m, 5H, Py-H and Ar-H), 6.82~7.00
(m, 4H, Ar-H), 4.93 (s, 2H, CH2), 4.02 (s, 2H, CH2), 3.60 (s, 3H, N-CH3), 2.34 (s, 3H, CH3); 13C NMR
(CDCl3):
δ 158.6 (d, J = 241 Hz), 152.6, 150.2, 149.6, 147.7, 147.0, 140.7, 139.1, 136.9, 133.9, 132.6, 130.8,
129.2, 124.1, 116.6, 116.4 (d, J = 14 Hz), 100.0, 75.4, 35.8, 34.3, 14.6. Anal. Calcd. for C25H22ClFN4O2S:
C 60.42; H 4.46; N 11.27. Found: C 60.36; H 4.38; N 11.38.
1-Methyl-3-methyl-5-(4-chlorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9r). Yellow oil, yield 70%. H NMR (CDCl3):
δ 8.19 (d, J = 2.0 Hz, 1H, Py-H), 7.79
(s, 1H, CH=N), 7.53–7.56 (m, 1H, Py-H), 7.21–7.26 (m, 5H, Py-H and Ar-H), 7.15 (d, J = 8.4 Hz, 2H,
Ar-H), 6.81 (d, J = 9.2 Hz, 2H, Ar-H), 4.92 (s, 2H, CH2), 4.02 (s, 2H, CH2), 3.60 (s, 3H, N-CH3), 2.33 (s,
3H, CH3); 13C NMR (CDCl3):
δ 155.1, 150.2, 149.5, 147.2, 147.0, 140.4, 139.1, 136.8, 133.9, 132.6, 130.8,
130.0, 129.2, 128.8, 124.1, 116.7, 100.3, 75.5, 35.8, 34.3, 14.4. Anal. Calcd. for C25H22Cl2N4O2S: C 58.48;
H 4.32; N 10.91. Found: C 58.61; H 4.20; N 10.82.
1-Methyl-3-methyl-5-(4-bromophenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9s). Yellow oil, yield 68%. H NMR (CDCl3):
δ 8.19 (d, J = 2.0 Hz, 1H, Py-H), 7.79
(s, 1H, CH=N), 7.54–7.56 (m, 1H, Py-H), 7.39 (d, J = 8.8 Hz, 2H, Ar-H), 7.14–7.23 (m, 5H, Py-H and
Ar-H), 6.76 (d, J = 8.8 Hz, 2H, Ar-H), 4.92 (s, 2H, CH2), 4.03 (s, 2H, CH2), 3.60 (s, 3H, N-CH3), 2.34 (s,
3H, CH3); 13C NMR (CDCl3):
δ 155.7, 150.2, 149.5, 147.0, 146.9, 140.5, 139.1, 136.9, 133.9, 132.8, 132.5,
130.8, 129.2, 124.1, 117.0, 116.1, 100.2, 75.4, 35.7, 34.2, 14.5. Anal. Calcd. for C25H22BrClN4O2S: C 53.82;
H 3.97; N 10.04. Found: C 53.95; H 3.85; N 9.92.
1-Methyl-3-methyl-5-(4-iodophenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9t). Yellow oil, yield 65%. H NMR (CDCl3):
δ 8.20 (d, J = 2.4 Hz, 1H, Py-H),
7.79 (s, 1H, CH=N), 7.53–7.60 (m, 3H, Py-H and Ar-H), 7.14–7.24 (m, 5H, Py-H and Ar-H), 6.65 (d,

Molecules 2017, 22, 878
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J = 8.8 Hz, 2H, Ar-H), 4.92 (s, 2H, CH2), 4.03 (s, 2H, CH2), 3.59 (s, 3H, N-CH3), 2.33 (s, 3H, CH3);
13C NMR (CDCl3):
156.6, 150.2, 149.6, 147.0, 146.9, 140.5, 139.1, 138.9, 136.9, 133.9, 132.6, 130.9, 129.3,
δ
124.1, 117.6, 100.3, 86.5, 75.5, 35.8, 34.3, 14.5. Anal. Calcd. for C25H22ClIN4O2S: C 49.64; H 3.67; N 9.26.
Found: C 49.73; H 3.79; N 9.15.
1-Methyl-3-methyl-5-(2,4-difluorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9u). Yellow oil, yield 63%. H NMR (CDCl3):
δ 8.19 (d, J = 2.4 Hz, 1H, Py-H), 7.78
(s, 1H, CH=N), 7.54–7.56 (m, 1H, Py-H), 7.16–7.37 (m, 5H, Py-H and Ar-H), 6.91–6.94 (m, 1H, Ar-H),
6.71–6.74 (m, 2H, Ar-H), 4.91 (s, 2H, CH2) 4.02 (s, 2H, CH2), 3.66 (s, 3H, N-CH3), 2.31 (s, 3H, CH3);
13C NMR (CDCl3):
δ 149.6, 148.9 (d, J = 334 Hz), 148.6 (d, J = 316 Hz), 147.1, 140.6, 140.3, 139.0, 137.0,
133.9, 132.6, 130.8, 129.1, 128.7, 124.2, 124.1, 117.5, 111.0 (d, J = 21 Hz), 105.6 (d, J = 21 Hz), 99.6, 75.4,
35.8, 34.2, 14.3. Anal. Calcd. for C25H21ClF2N4O2S: C 58.31; H 4.11; N 10.88. Found: C 58.18; H 4.23;
N 10.99.
1-Methyl-3-methyl-5-(2,4-dichlorophenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-methylthio)
1
phenylmethyl]-oxime (9v). Yellow oil, yield 66%. H NMR (CDCl3):
δ 8.19 (s, 1H, Py-H), 7.78 (s, 1H,
CH=N), 7.43–7.56 (m, 2H, Py-H and Ar-H), 7.08–7.23 (m, 6H, Py-H and Ar-H), 6.59 (d, J = 8.8 Hz, 1H,
Ar-H), 4.90 (s, 2H, CH2) 4.02 (s, 2H, CH2), 3.63 (s, 3H, N-CH3), 2.32 (s, 3H, CH3); 13C NMR (CDCl3):
δ 150.9, 150.2, 149.6, 147.2, 146.5, 140.1, 139.0, 136.9, 133.9, 132.6, 130.8, 130.5, 129.1, 129.0, 127.9, 124.1,
123.6, 116.3, 100.1, 75.4, 35.8, 34.2, 14.2. Anal. Calcd. for C25H21Cl3N4O2S: C 54.80; H 3.86; N 10.23.
Found: C 54.67; H 3.97; N 10.35.
1-(4-Methylphenyl)-3-methyl-5-(4-methylphenoxy)-1H-pyrazole-4-carbaldehyde-O-[4-(2-chloropyridin-5-yl-
1
methylthio)phenylmethyl]-oxime (9w). Yellow oil, yield 65%. H NMR (CDCl3):
δ 8.20 (d, J = 2.4 Hz,
1H, Py-H), 7.81 (s, 1H, CH=N), 7.51–7.54 (m, 1H, Py-H), 7.45 (d, J = 8.4 Hz, 2H, Ar-H), 7.15–7.22 (m,
5H, Py-H and Ar-H), 7.14 (d, J = 8.4 Hz, 2H, Ar-H), 7.03 (d, J = 8.4 Hz, 2H, Ar-H), 6.77 (d, J = 8.8 Hz,
2H, Ar-H), 4.97 (s, 2H, CH2), 4.01 (s, 2H, CH2), 2.43 (s, 3H, CH3), 2.31 (s, 3H, CH3), 2.27 (s, 3H, CH3);
13C NMR (CDCl3):
δ 154.8, 150.2, 149.6, 148.1, 147.5, 140.8, 139.0, 137.1, 135.1, 133.9, 133.1, 132.6,
130.9, 130.3, 129.7, 129.2, 128.9, 124.1, 122.1, 115.3, 101.6, 75.5, 35.9, 21.0, 20.6, 15.1. Anal. Calcd. for
C32H29ClN4O2S: C 67.53; H 5.14; N 9.84. Found: C 67.66; H 5.03; N 9.95.
3.2. Biological Tests
3.2.1. Acaricidal Activity and Insecticidal Activity Assay
All bioassays were performed on representative test organisms reared in the laboratory.
The bioassay was repeated in triplicate. Assessments were made on a dead/alive basis, and mortality
rates were corrected using Abbott’s formula. The acaricidal activities against Tetranychus cinnabarinus,
and insecticidal activities against Aphis medicaginis and Nilaparvata lugens of the target compounds
were tested by the spray method [26]. Under the Potter spray tower, horsebean leaves inoculated
with Tetranychus cinnabarinus were separately treated with solutions of tested compounds. After that,
the resultant horsebean leaves were kept in an observation room for normal cultivation at 24~27 ◦C.
Mortality was assessed 48 h after treatment. Each test was run three times and results were averaged.
Fenpyroximate was used as the control. Activities against Aphis medicaginis were evaluated by the
◦
similar procedure except that the culture temperature was reduced to 20~22 C. Abamectin was
selected as the control. Inhibitions of Nilaparvata lugens were tested on the rice seedlings, which was
inoculated with N. lugens first. After that, the resultant rice seedlings were kept in an observation
room for normal cultivation at 24~27 ◦C. Mortality was assessed 48 h after treatment. All the tests
were run with three duplicates and the results were averaged. Abamectin was also used as the control.
The larvicidal activities of the aimed compounds against Oriental armyworm were evaluated by foliar
application. Corn leaves were dipped into the obtained solutions for 2–3 s. After air-drying, the soaked
leaves were put into a culture dish with a piece of filter paper, followed by inoculation of 10 third-instar
Oriental armyworm larvae per dish. Covered with gauze and then kept in an observation room for

Molecules 2017, 22, 878
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normal cultivation at 24~27 ◦C. Mortality was assessed 48 h after treatment. The individuals who
didn’t respond to the touch of writing brush were recognized as dead. Each test was run three times
and results were averaged. Abamectin as the control compound was tested under the same condition.
3.2.2. Anticancer Activity Assay
Panc-1 (human pancreatic carcinoma cells), HepG2 (human hepatoma cells), or SGC-7901 (human
gastric cancer cells) at 104 cells per well were cultured overnight in 10% FBS DMEM in 96-well
flat-bottom microplates [27]. The cells were incubated in triplicate with, or without, different
concentrations of each test compound for 48 h. During the last 4 h incubation, 30
dye (MTT) solution (5 mg/mL) was added to each well. The resulting MTT-formazan crystals were
dissolved in 150 L DMSO, and absorbance was measured spectrophotometrically at 570 nm using an
µL of tetrazolium
µ
ELISA plate reader. The inhibition induced by each test compound at the indicated concentrations was
expressed as a percentage. The concentration required for 50% inhibition (IC50) was calculated using
the software (Graph Pad Prism, San Diego, CA, USA, Version 4.03).
4. Conclusions
In summary, a number of pyrazole oxime derivatives containing a substituted pyridyl subunit
were synthesized. Preliminary bioassays indicated that some of the title compounds showed wonderful
acaricidal activity against T. cinnabarinus at a concentration of 500
compound 9q still exhibited moderate acaricidal activity against T. cinnabarinus under the concentration
of 100 g/mL. Moreover, some target compounds were active against Oriental armyworm, A. medicaginis,
and N. lugen at 500 g/mL. Furthermore, some compounds such as 9b 9g 9l 9p 9q 9r 9s 9t 9u
and 9v possessed potent antiproliferative activities against HepG2 cells with IC50 values of 12.65,
17.27, 8.72, 7.24, 8.27, 1.53, 9.76, 9.13, 15.24, and 11.93 M, respectively, which were better than that of
5-fluorouracil (IC50 = 35.67 M). Further structural optimization and bioactivities about these pyrazole
µg/mL, among these derivatives,
µ
µ
,
,
,
,
,
,
,
,
,
µ
µ
oximes are currently in progress.
Supplementary Materials: Supplementary materials are available online: Figures S1–S46.
Acknowledgments: This work was funded by the National Natural Science Foundation of China (No. 21372135,
21475070), the Research Foundation of the Six People Peak of Jiangsu Province (No. 2013-SWYY-013).
Author Contributions: H.G. designed the research; C.C., J.C., N.B. performed the research and analyzed the data;
H.D. wrote the paper. All authors read and approved the final manuscript.
Conflicts of Interest: The authors declare no conflict of interest.
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Sample Availability: Samples of the compounds 9a–9w are available from the authors.
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2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
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(CC BY) license (http://creativecommons.org/licenses/by/4.0/).