Synthesis and Evaluation of 1,3,4-Thiadiazole Derivatives Containing Cyclopentylpropionamide as Potential Antibacterial Agent

Article abstract of DOI:10.1002/jhet.3576

This study aimed to identify new strategies for the control of these plant bacterial diseases by combining a pharmacophoric group of different bioactive compounds. A series of 3-cyclopentylpropionamide containing 1,3,4-thiadiazole derivatives was synthesized and characterized via ¹H-NMR, ¹³C-NMR, and HRMS. Bioassay results indicated that compounds 7a, 7d, 7j, 7m, 7n, and 7s had excellent antibacterial activity compared with the positive control. Among them, compound 7a exhibited remarkable inhibitory effect against Xoo with an EC₅₀ of 21.41?μg/mL, which surpassed that of thiodiazole copper (67.71?μg/mL) and bismerthiazol (69.05?μg/mL). Greenhouse condition tests further revealed that 7a had approximately equal curative activity and better protection activity (41.58%) against bacterial leaf blight of rice than that of thiodiazole copper and bismerthiazol (46.86 and 42.25%, respectively). Structure–activity relationship analysis exhibited that sulfone fragment favored inhibition. Overall, this study suggested that derivatives containing 1,3,4-thiadiazole 3-cyclopentylpropanamide can be used as new lead compounds for bactericide studies.

Full text of DOI:10.1002/jhet.3576

Month 2019
Synthesis and Evaluation of 1,3,4-Thiadiazole Derivatives Containing
Cyclopentylpropionamide as Potential Antibacterial Agent
*
*
Min Zhang, Weiming Xu, Kun Wei, Hongwu Liu, Qin Yang, Qin Liu, Liyun Yang, Yuqin Luo, and Wei Xue
State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green
Pesticide and Agricultural Bioengineering, Ministry of Education, Center for Research and Development of Fine
Chemicals, Guizhou University, Guiyang 550025, People’s Republic of China
*E-mail: xuweiming2009@163.com; wxue@gzu.edu.cn
Received January 13, 2019
DOI 10.1002/jhet.3576
Published online 00 Month 2019 in Wiley Online Library (wileyonlinelibrary.com).
This study aimed to identify new strategies for the control of these plant bacterial diseases by combining a
pharmacophoric group of different bioactive compounds. A series of 3-cyclopentylpropionamide containing
1,3,4-thiadiazole derivatives was synthesized and characterized via 1H-NMR, 13C-NMR, and HRMS. Bioas-
say results indicated that compounds 7a, 7d, 7j, 7m, 7n, and 7s had excellent antibacterial activity compared
with the positive control. Among them, compound 7a exhibited remarkable inhibitory effect against Xoo
with an EC50 of 21.41 μg/mL, which surpassed that of thiodiazole copper (67.71 μg/mL) and bismerthiazol
(69.05 μg/mL). Greenhouse condition tests further revealed that 7a had approximately equal curative activity
and better protection activity (41.58%) against bacterial leaf blight of rice than that of thiodiazole copper and
bismerthiazol (46.86 and 42.25%, respectively). Structure–activity relationship analysis exhibited that sul-
fone fragment favored inhibition. Overall, this study suggested that derivatives containing 1,3,4-
thiadiazole 3-cyclopentylpropanamide can be used as new lead compounds for bactericide studies.
J. Heterocyclic Chem., 00, 00 (2019).
INTRODUCTION
Currently, chemical pesticides have frequently been used
to prevent bacterial diseases, such as bismerthiazol and
thiodiazole copper. However, chemical pesticides enhance
the resistance of host plants and cannot effectively treat
infected plants under field conditions because of their low
efficiency and high phytotoxicity [10,11]. Thus, searching
for novel alternative antibacterial agents can still be a
challenge in the field of bactericide [12]. Heterocyclic
compounds have attracted the interest of pharmaceutical
chemists because of their special chemical structures
and diverse biological characteristics [13,14]. 1,3,4-
Thiadiazole derivatives possess widely biological
activities [15], such as antiviral [16,17], antibacterial
[18,19], insecticide [20], antifungal [21,22], anticancer
[23], and anti-inflammatory [24]. Cyclopentane is well
known because of its dimensional structure known as the
half-chair conformation of lower-energy state. However,
cyclopentane has emerged in several active compounds,
especially those connected with a flexible bond (2 carbon
or 3 carbon) and as an important pharmacophore.
Cyclopentamine is a sympathomimetic alkylamine and is
classified as a vasoconstrictor [25]. Peramivir could
Bacterial diseases are very common, and more than 500
kinds of plant bacterial diseases have been recorded.
Among the bacterial diseases, tomato bacterial wilt, citrus
canker, and rice bacterial leaf blight were caused by the
pathogens of Rs, Xac, and Xoo, respectively, which has
attracted considerable attention worldwide. Because of its
high mortality rate with a global distribution and an
unusual wide host range, Rs is one of the most
devastating plant pathogens worldwide [1,2]. Xac is a
common plant disease throughout the areas of tropical
and subtropical world [3] that affects most of the
commercial varieties of citrus, such as citrus canker,
decreases the quality and quantity of citrus fruits, and
results in huge economic losses [4]. Xoo is a pathogenic
Gram-negative bacterium in rice cultivation that can
invade rice xylem tissues through wounds or stomata
[5,6], which causes systemic infection and results in rice
bacterial leaf blight. Rice bacterial leaf blight disease
has a serious impact on each stage of rice growth and
seriously limits the yields of rice with huge economic
impact worldwide. Rice bacterial leaf blight causes a
yield loss of up to 80% [7–9].
protect healthy cells from novel viruses, as
a
neuraminidase inhibitor [26,27]. Candoxatril is a new
© 2019 Wiley Periodicals, Inc.

M. Zhang, W. Xu, K. Wei, H. Liu, Q. Yang, Q. Liu, L. Yang, Y. Luo, and W. Xue
Vol 000
effective therapeutic used in the treatment of people with
mild heart failure. The beneficial effects may begin to
improve the well-being of patients during everyday
activities [28]. Alfaprostol is developed as a stable and
selective analogue of prostaglandin F2α and is widely
used as a potent luteolytic agent in cows, mares, and
several new applications [29,30] (Fig. 1). Furthermore,
drugs containing flexible side chains, such as –CH2CH2–,
are conducive in improving the biological activity in most
cases.
In our previous work [31], we demonstrated that 1,3,4-
thiadiazole derivatives have remarkable antibacterial
activity against plant pathogens; however, no study has
been reported on cyclopentane (flexible side chains) that
focuses on the pharmacophoric group of 1,3,4-thiadiazole.
Biologically active fragments were incorporated by
versatile amides because of the biological importance of
1,3,4-thiadiazole and cyclopentane with flexible side
chains to discover and develop bioactive molecules. Here,
we report a series of novel 3-cyclopentylpropionamide
containing 1,3,4-thiadiazole sulfide or sulfone derivatives,
their synthesis, and antibacterial activity (Scheme 1).
scaffold was successfully accomplished. In the present
work, a solution of thiosemicarbazide and carbon disulfide
and disulfide mixture refluxed for 4 h and acidified with
concentrated HCl to obtain synthetic chemistry involves
the ring closure of thiosemicarbazide into 5-amino-1,3,4-
thiadiazole thiol 2 [32], converting to 1,3,4-thiadiazole
sulfide intermediate 3(a–w) by a substitution reaction
with a halogenated hydrocarbon in an aqueous solution
of potassium hydroxide at room temperature [6,8,12].
Intermediate 5 is obtained by heating to reflux with
thionyl chloride using 3-cyclopentylpropionic acid using
pyridine as a catalyst [33]. Further, intermediate 3(a–w)
and 5 were stirred under dichloromethane for 4 h to
obtain compound 6(a–w). Finally, it was oxidized with
H2O2 under acidic conditions of glacial acetic acid to
obtain a series of 3-cyclopentylpropionamide derivatives
7(a–u) containing 1,3,4-thiadiazole sulfide/sulfone. All
compounds displayed 1H-NMR and 13C-NMR and
HRMS consistent with the assigned structures. For the
1H-NMR spectra of compound 6, the single peak at
12.80–13.36 and 2.73–4.51 ppm reveals the presence of
–CONH and –SCH2–, respectively. For the 1H-NMR
spectra of compound 7, the singlet at 12.55–13.26
and 3.40–5.10 ppm reveals the presence of –CONH and
–SO2CH2– groups, respectively. Moreover, in HRMS
spectra, the considerable abundance of [M + H]+
ions indicated that the structure of the title compounds
is stable.
RESULTS AND DISCUSSION
Chemistry. The multistep synthesis of 3-cyclopentyl
propionamides bearing 1,3,4-thiadiazole sulfide or sulfone
Figure 1. Structure of several drugs containing cyclopentyl fragment. [Color figure can be viewed at wileyonlinelibrary.com]
Scheme 1. Synthetic route to the title compounds. Reagent and conditions: (a) Na2CO3, CS2, reflux, 4 h; (b) R–X, KOH, H2O, 25°C, stir, 8 h; (c) SOCl2,
CH2Cl2; (d) CH2Cl2, 25°C, stir; and (e) H2O2, (NH4)6MoO24.4H2O, acetic acid, stir.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2019
Synthesis and Evaluation of 1,3,4-Thiadiazole Derivatives Containing
Cyclopentylpropionamide as Potential Antibacterial Agent
Bioactivities. In vitro antibacterial activity. The in vitro
antibacterial evaluation of title compounds against Rs, Xoo,
and Xac were tested by the method of turbidimetric assay.
The results are compared with that of commercial
antibacterial agent thiodiazole copper (20% suspending
agent) and bismerthiazol (20% wettable powder), and the
results are listed in Tables 1–3.
copper (62.04% at 100 μg/mL and 39.77% at 50 μg/mL)
and bismerthiazol (56.43 and 44.06%).
As indicated in Table 2, several evaluated compounds
had excellent efficacy against Rs, Xoo, and Xac compared
with that of the positive control. For antibacterial activity
against Rs, compounds 7a, 7h, 7l, 7m, and 7o exhibited
excellent activity, and their control efficacies were 79.27–
92.34% at 100 μg/mL, and compounds 7h, 7l, 7m, and 7o
showed 75.68, 66.06, 73.82, and 72.72% at 50 μg/mL,
respectively, which were better than thiodiazole copper
(48.44% at 100 μg/mL and 26.12% at 50 μg/mL) and
bismerthiazol (52.90 and 37.88%). For Xac, compounds
7a, 7c, and 7f exhibited the most activity with inhibition
of 93.56, 97.47, and 82.23% at 100 μg/mL, which was
superior to thiodiazole copper (56.30% at 100 μg/mL) and
bismerthiazol (69.60% at 100 μg/mL). For antibacterial
activity against Xoo, most compounds indicated
significant activities, compared with the positive control.
At 100 μg/mL, compounds 7a, 7j, 7m, and 7s exhibited
excellent activity, and their control efficacies were 94.03,
83.47, 84.15, and 80.74%, respectively. At 50 μg/mL,
compound 7a exhibited the most activity with inhibition
of 82.97%, which was superior to thiodiazole copper
(62.04% at 100 μg/mL and 39.77% at 50 μg/mL) and
bismerthiazol (56.43 and 44.06%).
Table 1 indicates that most of the title compounds
exerted satisfactory efficacy against Rs, Xoo, and Xac,
compared with the positive control. For the antibacterial
activity against Rs, compounds 6f, 6n, 6t, and 6n
exhibited excellent activity. Their control efficacies at
100 μg/mL were 74.52, 73.90, 69.62, and 80.51%,
respectively, and 54.72, 51.13, 49.55, and 61.20%,
respectively, at 50 μg/mL, which outperforms that of
thiodiazole copper (48.44% at 100 μg/mL and 26.12% at
50 μg/mL) and bismerthiazol (52.90 and 37.88%). For
Xac, compounds 6c, 6d, 6p, 6s, and 6t exhibited
excellent activities, and their control efficacies were
81.12–90.43 and 51.30–66.10% at 100 and 50 μg/mL,
which were preferable to thiodiazole copper (56.30% at
100 μg/mL and 37.49% at 50 μg/mL) and bismerthiazol
(69.60 and 44.38%). For Xoo, 6t exhibited the most
activity with inhibition of 79.9% at 100 μg/mL and
58.55% at 50 μg/mL, which were better than thiodiazole
Table 1
Antibacterial activities of compound 6 (%).
Ralstonia solanacearum
Xac
Xoo
Compound
50 μg/mL
100 μg/mL
50 μg/mL
100 μg/mL
50 μg/mL
100 μg/mL
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
6q
6r
6s
6t
6u
6v
6w
23.25 1.40
33.49 2.40
28.69 2.29
23.31 0.54
40.55 1.12
54.72 0.90
20.78 0.61
42.62 1.91
18.11 4.52
—
45.63 2.10
42.46 0.49
20.10 0.42
51.13 0.33
41.79 1.21
24.13 1.06
47.15 1.56
49.28 1.25
—
56.42 1.25
52.98 0.82
40.10 2.31
26.76 1.45
58.60 1.20
74.52 1.46
—
61.18 0.59
43.59 0.51
66.1 1.15
64.64 0.94
39.04 4.04
31.97 0.45
38.13 7.62
31.44 1.01
38.57 7.01
45.00 0.91
64.06 1.08
41.97 1.22
48.15 4.94
44.56 2.26
42.08 0.37
57.59 0.78
47.75 1.16
25.28 0.46
51.30 1.33
42.37 0.88
24.04 1.26
43.85 5.22
—
70.49 2.69
57.80 1.42
90.43 0.95
79.92 1.99
46.73 1.86
53.56 3.69
47.39 4.54
59.01 1.32
43.89 12.59
55.46 0.17
67.07 0.56
63.11 0.66
58.07 0.58
50.98 0.67
62.55 1.55
81.92 0.21
69.07 0.78
52.27 1.16
83.12 1.94
71.35 1.07
52.94 2.94
63.61 2.92
31.32 1.22
56.30 2.09
69.6 0.79
33.29 1.20
31.43 1.31
37.63 1.08
22.60 1.54
36.42 1.74
25.40 0.93
23.11 2.27
30.71 0.49
28.61 4.30
24.63 3.13
19.36 2.11
38.94 0.78
27.32 1.41
34.72 0.45
31.89 2.56
27.66 2.25
44.82 0.62
36.18 2.03
42.58 0.60
58.55 1.02
33.80 2.07
16.07 1.12
20.32 1.18
39.77 2.77
44.06 1.79
49.33 0.49
52.36 1.44
61.87 0.82
46.53 0.57
48.62 0.87
44.58 1.32
40.48 0.83
51.20 1.10
43.74 2.15
48.26 1.07
36.43 1.78
57.18 0.40
47.83 0.82
58.73 0.66
62.17 1.88
46.07 0.77
59.78 0.87
62.75 0.79
69.44 1.63
79.90 0.80
48.60 1.58
39.43 2.25
47.66 2.72
62.04 0.67
56.43 1.37
62.13 1.37
48.21 1.08
47.82 1.91
67.88 0.42
65.99 2.12
55.29 7.03
73.90 1.04
62.17 0.82
41.75 13.36
63.31 0.63
65.34 0.64
20.19 1.94
69.62 0.20
80.51 0.56
35.39 2.72
63.25 2.26
48.44 4.52
66.89 0.64
49.55 0.62
61.20 1.05
23.69 1.28
40.95 1.22
26.12 3.52
41.46 0.81
Thiodiazole copper
Bismerthiazol
37.49 3.63
44.38 1.14
Journal of Heterocyclic Chemistry
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M. Zhang, W. Xu, K. Wei, H. Liu, Q. Yang, Q. Liu, L. Yang, Y. Luo, and W. Xue
Vol 000
Table 2
Antibacterial activities of target compound 7 (inhibition rate, %).
Ralstonia solanacearum
Xac
Xoo
Compound
50 μg/mL
100 μg/mL
50 μg/mL
100 μg/mL
50 μg/mL
100 μg/mL
7a
7b
7c
7d
7e
7f
7g
7h
7i
7j
7k
7l
7m
7n
7o
7p
39.81 3.26
52.52 0.57
—
38.11 12.36
34.53 1.00
67.63 4.95
32.95 1.86
75.68 2.81
—
41.13 9.02
53.24 3.52
66.06 2.17
73.82 7.88
46.62 13.16
72.72 5.73
34.90 7.79
51.53 10.93
35.86 10.87
43.34 5.87
60.54 6.40
48.47 5.01
26.12 3.25
41.46 0.81
79.52 5.28
73.52 0.40
—
78.28 8.82
48.39 1.28
72.72 5.73
49.35 0.65
80.16 0.81
74.39 3.68
—
77.74 7.92
82.19 1.08
79.27 2.60
60.26 0.93
92.34 1.62
75.71 12.27
70.62 8.32
64.60 6.67
58.80 9.74
76.46 4.88
—
42.31 1.46
38.58 0.59
51.82 12.36
—
20.09 0.67
33.78 1.23
34.79 4.03
16.27 7.34
55.96 5.83
47.39 6.45
—
93.56 5.03
66.42 1.46
97.47 1.99
—
33.41 1.38
82.23 4.24
52.01 0.27
—
64.36 0.73
51.78 3.61
55.21 8.92
44.47 7.82
67.34 1.84
53.69 2.15
53.25 8.13
43.54 2.03
59.01 0.59
43.44 6.15
57.15 0.25
47.00 2.08
53.73 1.27
56.30 2.09
69.6 0.79
82.97 8.49
48.36 1.88
24.58 4.12
51.85 6.55
37.15 1.08
15.72 9.34
31.66 2.11
—
12.75 6.67
60.86 7.20
26.13 0.78
20.45 2.84
59.23 6.33
—
37.84 5.43
33.69 2.67
34.90 12.76
57.47 5.78
53.51 7.85
72.65 3.43
67.18 5.19
39.77 2.77
44.06 1.79
94.03 0.57
68.35 1.39
69.34 7.28
77.85 0.35
52.78 0.93
38.98 9.76
49.94 0.64
—
45.93 2.28
83.47 4.68
—
64.26 0.89
84.15 0.76
78.24 2.57
54.62 4.89
—
—
42.81 2.50
27.53 1.29
45.67 2.88
25.9 7.73
48.95 7.49
30.25 6.62
49.45 0.5
41.19 0.75
38.78 13.85
34.12 4.29
44.38 1.14
7q
7r
7s
7t
—
76.04 4.85
80.74 9.34
75.81 3.59
—
62.04 0.67
56.43 1.37
7u
Thiodiazole copper
Bismerthiazol
48.44 4.52
66.89 0.64
Table 3
EC50 values of several target compounds against Xoo.
Compound
R1
CH3
CH2CH2CH3
CH2CO2C2H5
4-CN-Benzyl
3-F-Benzyl
4-F-Benzyl
—
Toxic regression
r2
EC50 (μg/mL)
7a
7d
7j
7m
7r
7s
y = 2.2958x + 1.952
y = 1.779x + 2.159
y = 1.6039x + 2.707
y = 2.4209x + 1.17
y = 1.6484x + 2.2875
y = 1.773x + 2.1948
y = 1.7806x + 1.7405
y = 1.8829x + 1.537
0.9857
0.9893
0.9747
0.9976
0.9224
0.9809
0.9985
0.9422
21.41 0.85
39.53 1.43
26.89 0.91
38.19 0.63
44.21 1.68
38.21 2.42
67.71 0.79
69.05 1.21
Thiodiazole copper
Bismerthiazol
—
Several compounds displayed excellent antibacterial
activities, and their EC50 values against Xoo were tested,
calculated, and listed in Table 3. Compounds 7a, 7d, 7j,
7m, and 7s showed excellent activity against Xoo, the
EC50 values were 21.41, 39.53, 26.89, 38.19, and
38.21 μg/mL, respectively, which were better than
thiodiazole copper (67.71 μg/mL) and bismerthiazol
(69.05 μg/mL).
In vivo antibacterial activity. The results of antibacterial
activities in vivo are listed in Table 4 and Figure 2.
At 14 days after spraying, the positive control and test
compound were morbidity in total and showed different
disease indexes and different control activities. At
200 μg/mL, compound 7a showed curative activity of
46.61% against rice bacterial leaf blight in vivo, which
surpassed bismerthiazol (30.21%) and thiodiazole copper
(40.86%). Compound 7a displayed remarkable protective
activity of 41.58% against rice bacterial leaf blight,
which has approximately equal activity compared with
bismerthiazol (42.25%) and thiodiazole copper (46.86%).
The leaves treated by compound 7a grew uniformly and
vigorously with small leaf blight.
As previously mentioned, the differences of target
compounds were due to their different moieties of
thioester (compound 6 series) and sulfone (compound 7
series) and with different substituents of R group next to
sulfur. On the basis of the biological test results, the
structure–activity relationship can be evaluated based on
the parallel activity comparison between compound 6 and
7 series against antibacterial activity at the same
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2019
Synthesis and Evaluation of 1,3,4-Thiadiazole Derivatives Containing
Cyclopentylpropionamide as Potential Antibacterial Agent
Table 4
Activity of 7a against rice bacterial leaf blight in vivo at 200 μg/mL.
Curative activity
Protection activity
Morbidity
(%)
Treatment
Disease index (%)
Efficiency (%)a
Disease index (%)
Efficiency (%)a
7a
100
100
100
100
37.86
41.94
49.55
70.91
46.61 1.77b
40.86 1.22c,d
30.12 2.15b,c
/
41.43
37.68
40.95
70.91
41.58 0.94c,d
46.86 0.70d
42.25 1.68b,c,d
/
Thiodiazole copper
Bismerthiazol
Control Check (CK)
Different lowercase letters indicate the values of curative activity, and there was a significant difference between the different treatment groups, p < 0.05.
aStatistical analysis was performed using the analysis of variance method under the condition of equal variances assumed (p > 0.05) and equal variances
not assumed (p < 0.05).
Figure 2. Curative and protection activities of 7a against rice bacterial leaf blight under greenhouse conditions at 200 μg/mL. [Color figure can be viewed
at wileyonlinelibrary.com]
concentration (100 and 50 μg/mL), EC50 values, and
in vivo antibacterial activity test of several used
compounds. Most of the compounds exerted remarkable
antibacterial activity. However, in total, thioester
derivative (compound 6 series) showed lower activities
than that of sulfone derivative (compound 7 series). For
Rs, the antibacterial inhibition values were 6a < 7a,
6b < 7b, 6d < 7d, 6h < 7h, 6k < 7k, 6l < 7l, and
6m < 7m. For Xoo, the antibacterial inhibition values
were 6a < 7a, 6b < 7b, 6c < 7c, 6d < 7d, 6k < 7k,
6l < 7l, and 6m < 7m. The R group mainly includes
alkane and aromatic groups. In general, no obvious
differences were observed between the different
substituents. However, some subtle differences were
observed, in which the length of the alkane carbon chain
has an effect on the activity, and the short carbon chain
favors activity. For Xoo, the antibacterial inhibition
values were 7a > 7b, 7c, 7d, and 7e. When the R group
is aromatic, there are small differences in activities of the
title compounds for electron-donating or electron-
withdrawing groups.
CONCLUSIONS
In summary, two series of derivatives containing 1,3,4-
thiadiazole were designed and synthesized by merging
the structural features of thioester/sulfone and
cyclopentylpropanamide. Bioassay results showed that
several compounds, such as 7a, 7d, 7j, 7m, 7n, and 7s
show excellent antibacterial activity compared with that of
the positive control. Preliminary structure–activity
relationship analysis exhibited that an aromatic amino
acid fragment, such as phenylalanine or tryptophan, is
essential for the inhibition. Among them, compound 7a
exhibited remarkable inhibitory effect against Xoo, in
which its EC50 value is 21.41 μg/mL, which was higher
than that of thiodiazole copper (67.71 μg/mL) and
bismerthiazol (69.05 μg/mL). Furthermore, greenhouse
condition tests revealed that 7a has better protection
activity (41.58%) against bacterial leaf blight of rice than
that of thiodiazole copper and bismerthiazol (46.86 and
42.25%, respectively). These results suggested that 7a can
be extensively developed as potential antibacterial agents.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Zhang, W. Xu, K. Wei, H. Liu, Q. Yang, Q. Liu, L. Yang, Y. Luo, and W. Xue
Vol 000
EXPERIMENTAL
1.78–1.67 (m, 3H, cyclopentane–H), 1.63–1.55 (m, 4H,
cyclopentane–H), 1.52–1.42 (m, 2H, cyclopentane–H),
1.34 (t, J = 7.3 Hz, 3H, CH3), 1.10–1.06 (m, 2H,
cyclopentane–CH2). 13C-NMR (101 MHz, DMSO-d6) δ:
172.14, 159.01, 158.81, 34.58, 32.40, 31.25, 28.48,
Instruments.
The melting points (uncorrected) were
measured with micromelting point apparatus (Beijing
Tech. Instrument, Beijing, China), by tetramethylsilane as
25.13, 15.22. ESI-MS m/z: 286.1 [M + H]+.
1
the internal standard. H-NMR and 13C-NMR were mea-
N-(5-(Allylthio)-1,3,4-thiadiazol-2-yl)-3-cyclopentylpropana
mide (6c). White solid, yield 70.3%, mp 153.9–154.2°С.
sured with a Bruker ASCEND 400 NMR spectrometer
(Bruker Corp., Billerica, MA) and a JEOL-ECX 500
NMR spectrometer (JEOL, Japan) in CDCl3 or
DMSO-d6. Q Exactive apparatus (The United States,
Thermo Scientific) was used conducting HRMS. All
reagents are analytical reagent or CP.
1H-NMR (400 MHz, CDCl3) δ: 13.22 (s, 1H, NH), 6.03–
5.92 (m, 1H, CH), 5.30 (d, J = 16.9 Hz, 1H, CH¼CH2),
5.18 (d, J = 10.0 Hz, 1H, CH¼CH2), 3.86 (d, J = 7.0 Hz,
2H, SCH2), 2.78–2.74 (m, 2H, COCH2), 1.84–1.77 (m,
5H, cyclopentane–H), 1.66–1.58 (m, 2H, cyclopentane–
H), 1.56–1.49 (m, 2H, cyclopentane–H), 1.21–1.12 (m,
2H, cyclopentane–CH2). 13C-NMR (101 MHz, CDCl3) δ:
172.27, 161.00, 159.16, 132.27, 119.29, 39.79, 36.87,
35.49, 32.45, 31.40, 25.15. ESI-MS m/z: 298.10385
Preparation for 5-amino-1,3,4-thiadiazole-2-thiol (2).
A
solution of thiosemicarbazide (0.1 mol) in absolute
ethanol (50 mL), anhydrous sodium carbonate
(0.045 mol), and carbon disulfide (0.1 mol) was added
slowly, refluxed, and stirred for 4 h. The solvent was
removed under reduced pressure, and the solid was
dissolved with 50 mL water and acidified with
concentrated hydrochloric acid to afford corresponding
solid product 11.3 g, yield 85%, mp 233–235°С [31].
[M + H]+.
3-Cyclopentyl-N-(5-(propylthio)-1,3,4-thiadiazol-2-yl)propa
namide (6d).
White solid, yield 67.2%, mp 114.3–
1
115.7°С. H-NMR (400 MHz, CDCl3) δ: 13.22 (s, 1H,
NH), 3.24–3.20 (m, 2H, SCH2), 2.78–2.74 (m, 2H,
COCH2), 1.88–1.81 (m, 5H, cyclopentane–H), 1.79–1.77
(m, 2H, cyclopentane–H), 1.66–1.60 (m, 2H,
cyclopentane–H), 1.56–1.51 (m, 2H, cyclopentane–H),
1.21–1.14 (m, 2H, cyclopentane–CH2), 1.06 (t,
J = 7.4 Hz, 3H, CH3). 13C-NMR (101 MHz, CDCl3) δ:
172.25, 160.61, 160.33, 39.79, 36.03, 35.47, 32.45,
31.43, 25.16, 22.79, 13.27. ESI-MS m/z: 300.1
Preparation for 3-cyclopentylpropanoyl chloride (5).
A
solution of thionyl chloride (0.3 mol) was added to 3-
cyclopentylpropanoic acid (0.1 mol), pyridine (1 mmol)
was added dropwise as catalyst. The mixture was
stirred and heated for reflux for 5 h, then slowly added
to ice water to remove excess oxaloyl chloride and
pyridine, colorless liquid product was afford by
extracting and then vacuum freeze drying at ꢀ50°С for
1 h, yield 83.85% [32].
[M + H]+.
3-Cyclopentyl-N-(5-(isopropylthio)-1,3,4-thiadiazol-2-yl)
propanamide (6e). White solid, yield 44.7%, mp 144.7–
Preparation for 3-cyclopentyl-N-(5-(methylthio)-1,3,4-
thiadiazol-2-yl)propanamide (6a–6w). The intermediate 3
1
145.2°С. H-NMR (400 MHz, CDCl3) δ: 13.27 (s, 1H,
NH), 3.89–3.79 (1H, SCH), 2.79–2.75 (m, 2H,
COCH2), 1.88–1.79 (m, 5H, cyclopentane–H), 1.66–
1.60 (m, 2H, cyclopentane–H), 1.54–1.50 (m, 2H,
cyclopentane–H), 1.46–1.45 (d, J = 6.8 Hz, 6H, 2CH3),
1.18–1.13 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.30, 161.15, 159.11, 40.13,
39.78, 35.50, 32.43, 31.41, 25.15, 23.33. ESI-MS m/z:
(2.1 mmol) was dissolved with 40 mL methylene chloride
and slowly added 3-cyclopentyl propionyl chloride
(2 mmol). The mixture was stirred at room temperature
for 4 h. The mixture was poured into 20 mL water and
extracted with dichloromethane. Then, anhydrous Na2SO4
was used to dry the organic layer and decompress
the solvent. Finally, anhydrous ethanol was used for
recrystallization to obtain the corresponding solid
300.1 [M + H]+.
N-(5-(Butylthio)-1,3,4-thiadiazol-2-yl)-3-cyclopentylpropana
mide (6f). White solid, yield 65.8%, mp 129.6–130.4°С.
products.
3-Cyclopentane-N-(5-(methylthio)-1,3,4-thiadiazol-2-yl)
1H-NMR(400 MHz, CDCl3) δ: 13.23 (s, 1H, NH), 3.26–
3.23 (m, 2H, SCH2), 2.78–2.74 (m, 2H, COCH2), 1.92–
1.78 (m, 5H, cyclopentane–H), 1.76–1.72 (m, 2H,
cyclopentane–H), 1.66–1.59 (m, 2H, cyclopentane–H),
1.55–1.43 (m, 4H, 2CH2), 1.20–1.12 (m, 2H,
cyclopentane–CH2), 0.95 (t, J = 7.4 Hz, 3H, CH3). 13C-
NMR (101 MHz, CDCl3) δ: 172.26, 160.60, 160.39,
39.78, 35.46, 33.82, 32.46, 31.44, 31.36, 25.16, 21.83,
propanamide (6a).
White solid, yield 74.5%, mp 146–
1
146.8°С. H-NMR (400 MHz, CDCl3) δ: 13.24 (s, 1H,
NH), 2.78–2.74 (m, 5H, COCH2, SCH3), 1.91–1.77 (m,
5H, cyclopentane–H), 1.64–1.58 (m, 2H, cyclopentane–
H), 1.56–1.49 (m, 2H, cyclopentane–H), 1.21–1.12 (m,
2H, CH2). 13C-NMR (101 MHz, CDCl3) δ: 172.27,
161.17, 160.47, 39.83, 35.49, 32.42, 31.43, 25.17, 16.04.
ESI-MS m/z: 272.0 [M + H]+.
3-Cyclopentane-N-(5-(ethylthio)-1,3,4-thiadiazol-2-yl)propa
13.57. ESI-MS m/z: 314.1 [M + H]+.
namide (6b). White solid, yield 52%, mp 135–136.2°С.
3-Cyclopentyl-N-(5-(pentylthio)-1,3,4-thiadiazol-2-yl)propa
1H-NMR (400 MHz, DMSO-d6) δ: 12.58 (s, 1H, NH),
3.25–3.19 (m, 2H, SCH2), 2.50–2.46 (m, 2H, COCH2),
namide (6g). White solid, yield 55%, mp 158.6–159.4°С.
1H-NMR (500 MHz, CDCl3) δ: 13.27 (s, 1H, NH), 3.24–
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2019
Synthesis and Evaluation of 1,3,4-Thiadiazole Derivatives Containing
Cyclopentylpropionamide as Potential Antibacterial Agent
3.21 (m, 2H, SCH2), 2.77–2.71 (m, 2H, COCH2), 1.88–
1.76 (m, 7H, cyclopentane–H), 1.62–1.57 (m, 2H,
cyclopentane–H), 1.52–1.50 (m, 2H, CH2), 1.44–1.38 (m,
2H, CH2), 1.36–1.30 (m, 2H, CH2), 1.18–1.11 (m, 2H,
cyclopentane–CH2), 0.90 (t, J = 7.2 Hz, 3H, CH3). 13C-
NMR (126 MHz, CDCl3) δ: 172.36, 160.65, 160.48,
39.85, 35.55, 34.15, 32.54, 31.53, 30.93, 29.09, 25.25,
N-(5-((3-Cyanobenzyl)thio)-1,3,4-thiadiazol-2-yl)-3-cyclopen
tylpropanamide (6l). White solid, yield 68.7%, mp 162.8–
1
163.5°С. H-NMR (400 MHz, CDCl3) δ: 13.18 (s, 1H,
NH), 7.70 (s, 1H, Ar–H), 7.65 (d, J = 7.8 Hz, 1H,
Ar–H), 7.59 (d, J = 7.8 Hz, 1H, Ar–H), 7.45 (t,
J = 7.8 Hz, 1H, Ar–H), 4.49 (s, 2H, SCH2), 2.78–2.74
(m, 2H, COCH2), 1.86–1.77 (m, 5H, cyclopentane–H),
1.62–1.55 (m, 2H, CH2), 1.50–1.46 (m, 2H,
cyclopentane–H), 1.19–1.11 (m, 2H, cyclopentane–CH2).
13C-NMR (101 MHz, CDCl3) δ: 172.17, 161.13, 158.34,
138.14, 133.38, 132.41, 131.55, 129.61, 118.40, 112.89,
39.77, 36.93, 35.44, 32.45, 31.35, 25.14. ESI-MS m/z:
22.30, 14.05. ESI-MS m/z: 328.1 [M + H]+.
N-(5-(sec-Butylthio)-1,3,4-thiadiazol-2-yl)-3-cyclopentylpro
panamide (6h). White solid, yield 56%, mp 86.2–87.4°С.
1H-NMR(400 MHz, CDCl3) δ: 13.36 (s, 1H, NH), 3.71–
3.62 (m, 1H, SCH), 2.79–2.76 (m, 2H, COCH2), 1.88–
1.79 (m, 5H, cyclopentane–H), 1.77–1.73 (m, 2H,
CH2CH3), 1.66–1.60 (m, 2H, cyclopentane–H), 1.56–1.51
(m, 2H, cyclopentane–H), 1.44 (d, J = 6.8 Hz, 3H, CH3),
1.20–1.12 (m, 2H, cyclopentane–CH2), 1.05 (t,
J = 7.4 Hz, 3H, CH3). 13C-NMR (101 MHz, CDCl3) δ:
172.34, 161.13, 159.19, 46.69, 39.79, 35.49, 32.45,
31.42, 29.71, 25.15, 20.92, 11.40. ESI-MS m/z: 314.1
373.1 [M + H]+.
N-(5-((4-Cyanobenzyl)thio)-1,3,4-thiadiazol-2-yl)-3-cyclopen
tylpropanamide (6m). White solid, yield 61%, mp 167.5–
1
168.8°С. H-NMR (500 MHz, CDCl3) δ: 13.21 (s, 1H,
NH), 7.59 (d, J = 8.0 Hz, 2H, Ar–H), 7.49 (d,
J = 8.1 Hz, 2H, Ar–H), 4.48 (s, 2H, SCH2), 2.74–2.71
(m, 2H, COCH2), 1.80–1.74 (m, 5H, cyclopentane–H),
1.59–1.53 (m, 2H, cyclopentane–H), 1.47–1.44 (m, 2H,
cyclopentane–H), 1.15–1.08 (m, 2H, cyclopentane–CH2).
13C-NMR (126 MHz, CDCl3) δ: 172.23, 161.19,
158.43, 141.97, 132.59, 129.78, 118.57, 111.80, 39.84,
[M + H]+.
3-Cyclopentyl-N-(5-((2-methylbutyl)thio)-1,3,4-thiadiazol-2-
yl)propanamide (6i). White solid, yield 77%, mp 100.3–
1
101.6°С. H-NMR (400 MHz, CDCl3) δ: 13.35 (s, 1H,
NH), 3.31–3.26 (m, 1H, SCH), 3.14–3.09 (m, 1H, S–
CH), 2.79–2.75 (m, 2H, COCH2), 1.88–1.77 (m, 7H,
cyclopentane–H, CH2), 1.64–1.60 (m, 2H, cyclopentane–
H), 1.55–1.51 (m, 2H, cyclopentane–H), 1.35–1.24 (m,
1H, CH), 1.20–1.12 (m, 2H, cyclopentane–CH2), 1.04
(d, J = 6.7 Hz, 3H, CH3), 0.93 (t, J = 7.4 Hz,
3H, CH3). 13C-NMR (101 MHz, CDCl3) δ: 172.30,
160.78, 160.53, 40.81, 39.78, 35.45, 34.80, 32.48,
31.45, 28.60, 25.17, 18.73, 11.28. ESI-MS m/z: 328.1
37.42, 35.50, 32.53, 31.42, 25.22. ESI-MS m/z: 373.1
[M + H]+.
3-Cyclopentyl-N-(5-((2-methylbenzyl)thio)-1,3,4-thiadiazol-
2-yl)propanamide (6n).
White solid, yield 88.6%, mp
128.3–129.2°С. 1H-NMR (400 MHz, CDCl3) δ: 13.21
(s, 1H, NH), 7.27 (d, J = 8.0 Hz, 2H, Ar–H), 7.13
(d, J = 7.9 Hz, 2H, Ar–H), 4.44 (s, 2H, SCH2), 2.78–
2.75 (m, 2H, COCH2), 2.33 (s, 3H, CH3), 1.90–
1.77 (m, 5H, cyclopentane–H), 1.66–1.59 (m, 2H,
cyclopentane–H), 1.55–1.47 (m, 2H, cyclopentane–H),
1.25–1.13 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.24, 160.89, 159.66, 137.06,
133.47, 130.77, 130.10, 128.38, 126.34, 39.81, 36.66,
35.58, 32.47, 31.44, 25.16, 19.20. ESI-MS m/z: 362.1
[M + H]+.
Ethyl 2-((5-(3-cyclopentylpropionylamino)-1,3,4-thiadiazol-
2-yl)thio)acetate (6j). White solid, yield 63%, mp 121.2–
121.7°С. 1H-NMR(400 MHz, CDCl3) δ: 13.21 (s, 1H,
NH), 4.25–4.20 (m, 2H, CH2), 4.05 (s, 2H, SCH2), 2.76–
2.72 (m, 2H, COCH2), 1.88–1.77 (m, 5H, cyclopentane–
H), 1.67–1.61 (m, 2H, cyclopentane–H), 1.58–1.52 (m,
2H, cyclopentane–H), 1.28 (t, J = 7.1 Hz, 3H, CH3),
1.17–1.12 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.26, 167.90, 161.19, 158.21,
62.13, 39.72, 35.43, 32.45, 31.42, 25.16, 14.14. ESI-MS
[M + H]+.
3-Cyclopentyl-N-(5-((3-methylbenzyl)thio)-1,3,4-thiadiazol-
2-yl)propanamide (6o).
White solid, yield 71.6%, mp
1
165.6–166.3°С. H-NMR (500 MHz, CDCl3) δ: 13.30 (s,
1H, NH), 7.23–7.17 (m, 3H, Ar–H), 7.11 (s, 1H, Ar–H),
4.44 (s, 2H, SCH2), 2.79–2.76 (m, 2H, COCH2), 2.34 (s,
3H, CH3), 1.86–1.77 (m, 5H, cyclopentane–H), 1.60–
1.57 (m, 2H, cyclopentane–H), 1.50–1.46 (m, 2H.
cyclopentane–H), 1.18–1.13 (m, 2H, cyclopentane–CH2).
13C-NMR (126 MHz, CDCl3) δ: 172.33, 160.89, 159.71,
138.59, 135.77, 129.78, 128.76, 126.14, 39.86, 38.28,
35.58, 32.53, 31.51, 25.21, 21.47. ESI-MS m/z: 362.1
m/z: 378.0 [M + H]+.
N-(5-(Benzylthio)-1,3,4-thiadiazol-2-yl)-3-cyclopentylpropa
namide (6k). White solid, yield 63%, mp 166–167°С. 1H-
NMR (500 MHz, CDCl3) δ: 13.27 (s, 1H, NH), 7.40–7.37
(m, 2H, Ar–H), 7.34–7.26 (m, 3H, Ar–H), 4.47 (s, 2H,
SCH2), 2.79–2.75 (m, 2H, COCH2), 1.88–1.75 (m, 5H,
cyclopentane–H), 1.63–1.55 (m, 2H, cyclopentane–H),
1.53–1.45 (m, 2H, cyclopentane–H), 1.20–1.11 (dd,
J = 19.1, 7.1 Hz, 2H, cyclopentane–CH2). 13C-NMR
(126 MHz, CDCl3) δ: 172.35, 160.99, 159.54, 136.05,
129.10, 128.86, 128.03, 39.88, 38.29, 35.59, 32.55,
31.51, 25.23. ESI-MS m/z: 348.1 [M + H]+.
[M + H]+.
3-Cyclopentyl-N-(5-((4-methylbenzyl)thio)-1,3,4-thiadiazol-
2-yl)propanamide (6p).
White solid, yield 73.8%, mp
1
178.7–179.6°С. H-NMR (400 MHz, CDCl3) δ: 13.21 (s,
1H, NH), 7.27 (d, J = 8.0 Hz, 2H, Ar–H), 7.13 (d,
J = 7.9 Hz, 2H, Ar–H), 4.44 (s, 2H, SCH2), 2.80–2.74
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Zhang, W. Xu, K. Wei, H. Liu, Q. Yang, Q. Liu, L. Yang, Y. Luo, and W. Xue
Vol 000
(m, 2H, COCH2), 2.33 (s, 3H, CH3), 1.88–1.77 (m, 5H,
cyclopentane–H), 1.66–1.59 (m, 2H, cyclopentane–H),
1.53–1.47 (m, 2H, cyclopentane–H), 1.18–1.13 (m, 2H,
cyclopentane–CH2). 13C-NMR(101 MHz, CDCl3) δ:
172.23, 160.84, 159.66, 137.73, 132.85, 129.46, 128.92,
39.81, 38.09, 35.51, 32.46, 31.43, 25.16, 21.18. ESI-MS
172.00, 160.83, 158.80, 140.36, 130.29, 129.30, 125.72,
125.68, 122.60, 39.75, 37.36, 35.47, 32.44, 31.35, 25.12.
ESI-MS m/z: 416.1 [M + H]+.
3-Cyclopentyl-N-(5-((3-methoxybenzyl)thio)-1,3,4-thiadiazol-
2-yl)propanamide (6u).
White solid, yield 49.2%, mp
1
114.3–115.7°С. H-NMR (400 MHz, CDCl3) δ: 13.24 (s,
1H, NH), 7.26–7.22 (m, 1H, Ar–H), 6.97–6.94 (m, 2H,
Ar–H), 6.84–6.81 (m, 1H, Ar–H), 4.45 (s, 2H, SCH2),
3.79 (s, 3H, OCH3), 2.79–2.75 (m, 2H, COCH2), 1.92–
1.77 (m, 5H, cyclopentane–H), 1.63–1.55 (m, 2H,
cyclopentane–H), 1.53–1.47 (m, 2H, cyclopentane–H),
1.20–1.12 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.25, 160.90, 159.85, 159.48,
137.40, 129.79, 121.32, 114.66, 113.37, 55.26, 39.79,
38.24, 35.51, 32.46, 31.42, 25.16. ESI-MS m/z: 378.1
m/z: 362.1 [M + H]+.
3-Cyclopentyl-N-(5-((2-fluorobenzyl)thio)-1,3,4-thiadiazol-2-
yl)propanamide (6q). White solid, yield 59%, mp 145.8–
1
146.2°С. H-NMR (400 MHz, CDCl3) δ: 13.29 (s, 1H,
NH), 7.42–7.38 (m, 1H, Ar–H), 7.28–7.25 (m, 1H,
Ar–H), 7.10–7.04 (m, 2H, Ar–H), 4.51 (s, 2H, SCH2),
2.79–2.76 (m, 2H, COCH2), 1.90–1.79 (m, 5H,
cyclopentane–H), 1.61–1.55 (m, 2H, cyclopentane–H),
1.50–1.47 (m, 2H, cyclopentane–H), 1.20–1.13 (m, 2H,
cyclopentane–CH2). 13C-NMR (101 MHz, CDCl3) δ:
172.29, 162.17, 161.15, 159.70, 159.02, 130.00, 130.96,
129.88, 129.80, 124.32, 124.28, 123.55, 123.40, 115.79,
115.58, 39.77, 35.48, 32.46, 31.42, 25.14. ESI-MS m/z:
[M + H]+.
N-(5-((2-Bromoethyl)sulfonyl)-1,3,4-thiadiazol-2-yl)-3-
cyclopentylpropanamide (6v).
White solid, yield 52.7%,
mp 246.9–247.5°С. 1H-NMR (400 MHz, CDCl3) δ:
13.20 (s, 1H, NH), 3.74–3.69 (m, CH2Br), 3.67–3.63
(m, 2H, SCH2), 2.79–2.75 (m, 2H, COCH2), 1.90–1.79
(m, 5H, cyclopentane–H), 1.65–1.59 (m, 2H,
cyclopentane–H), 1.57–1.52 (m, 2H, cyclopentane–H),
1.20–1.14 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.26, 161.12, 158.28, 39.68,
35.47, 34.91, 32.52, 31.41, 29.23, 25.18. ESI-MS m/z:
366.1 [M + H]+.
3-Cyclopentyl-N-(5-((3-fluorobenzyl)thio)-1,3,4-thiadiazol-2-
yl)propanamide (6r). White solid, yield 66%, mp 145.4–
1
146.2°С. H-NMR (400 MHz, CDCl3) δ: 13.16 (s, 1H,
NH), 7.31–7.27 (m, 1H, Ar–H), 7.16–7.10 (d,
J = 7.7 Hz, 2H, Ar–H), 7.00–6.95 (m, 1H, Ar–H),
4.45 (s, 2H, SCH2), 2.78–2.74 (m, 2H, COCH2), 1.90–
1.75 (m, 5H, cyclopentane–H), 1.64–1.57 (m, 2H,
cyclopentane–H), 1.51–1.47 (m, 2H, cyclopentane–H),
1.17–1.11 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.20, 164.05, 161.60, 161.01,
158.95, 138.70, 138.63, 130.29, 130.21, 124.63,
124.60, 116.07, 115.85, 115.03, 114.82, 39.77, 37.51,
35.47, 32.44, 31.38, 25.13. ESI-MS m/z: 366.1
364.0 [M + H]+.
N-(5-((4-Chlorobenzyl)thio)-1,3,4-thiadiazol-2-yl)-3-
cyclopentylpropanamide (6w). White solid, yield 74.1%,
1
mp 188.4–189.2°С. HNMR (400 MHz, CDCl3) δ: 12.95
(s, 1H, NH), 7.30 (d, J = 6.8 Hz, 4H, Ar–H), 4.43 (s, 2H,
SCH2), 2.74 (s, 2H, COCH2), 1.80 (m, 5H,
cyclopentane–H), 1.54 (m, 4H, cyclopentane–H), 1.15
(m, 2H, cyclopentane–CH2). 13CNMR (101 MHz,
CDCl3) δ: 172.09, 160.86, 159.03, 134.69, 133.81,
130.32, 128.93, 39.78, 37.44, 35.48, 32.45, 31.37, 25.14.
ESI-MS m/z: 382.0 [M + H]+.
[M + H]+.
3-Cyclopentyl-N-(5-((4-fluorobenzyl)thio)-1,3,4-thiadiazol-2-
yl)propanamide (6s). White solid, yield 55.1%, mp 164.3–
165.1°С. 1H-NMR(400 MHz, CDCl3) δ: 13.07 (s, 1H,
NH), 7.37–7.34 (m, 2H, Ar–H), 7.01 (t, J = 8.6 Hz, 2H,
Ar–H), 4.44 (s, 2H, SCH2), 2.77–2.73 (m, 2H, COCH2),
1.87–1.77 (m, 5H, cyclopentane–H), 1.62–1.59 (m, 2H,
cyclopentane–H), 1.53–1.47 (m, 2H, cyclopentane–H),
1.20–1.13 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.21, 160.80, 159.67, 138.53,
135.74, 129.71, 128.74, 126.07, 39.80, 38.28, 35.52,
32.46, 31.44, 25.15, 21.38. ESI-MS m/z: 366.1
Preparation for 3-cyclopentyl-N-(5-(methylsulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7a–7u). After compound 6
(1 mmol) dissolved in glacial acetic acid (20 mL), a
solution of 30% hydrogen peroxide (3 mmol) and
ammonium molybdate (0.005 mmol) were added in
batches, after stirring for 1 h at room temperature and
adding to water (50 mL). The product was filtered and
recrystallized from ethanol give the title compound 7.
3-Cyclopentyl-N-(5-(methylsulfonyl)-1,3,4-thiadiazol-2-yl)
propanamide (7a). White solid, yield 71.8%, mp 187.1–
[M + H]+.
3-Cyclopentyl-N-(5-((4-(trifluoromethyl)benzyl)thio)-1,3,4-
thiadiazol-2-yl)propanamide (6t). White solid, yield 49.2%,
1
187.4°С. H-NMR (400 MHz, CDCl3) δ: 12.73 (s, 1H,
mp 211.8–212.2°С. 1H-NMR (400 MHz, CDCl3) δ:
12.80 (s, 1H, NH), 7.58 (d, J = 8.2 Hz, 2H, Ar–H),
7.51 (d, J = 8.2 Hz, 2H, Ar–H), 4.51 (s, 2H, SCH2),
2.75–2.71 (m, 2H, COCH2), 1.88–1.76 (m, 5H,
cyclopentane–H), 1.61–1.59 (m, 2H, cyclopentane–H),
1.55–1.47 (m, 2H, cyclopentane–H), 1.17–1.10 (m, 2H,
cyclopentane–CH2). 13C-NMR (101 MHz, CDCl3) δ:
NH), 3.40 (s, 3H, SO2CH3), 2.79–2.75 (m, 2H, COCH2),
1.89–1.80 (m, 5H, cyclopentane–H), 1.65–1.62 (m, 2H,
cyclopentane–H), 1.56–1.52 (m, 2H, cyclopentane–H),
1.21–1.12 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.27, 163.93, 163.40, 43.28,
39.70, 35.66, 32.40, 31.27, 25.15. ESI-MS m/z: 304.0
[M + H]+.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2019
Synthesis and Evaluation of 1,3,4-Thiadiazole Derivatives Containing
Cyclopentylpropionamide as Potential Antibacterial Agent
3-Cyclopentyl-N-(5-(ethylsulfonyl)-1,3,4-thiadiazol-2-yl)
propanamide (7b).
δ: 173.09, 162.93, 161.61, 55.03, 34.67, 32.39, 31.06,
25.14, 24.53, 21.13, 13.85. ESI-MS m/z: 346.1 [M + H]+.
White solid, yield 68%, mp 189.7–
190.6°С. 1H-NMR (500 MHz, DMSO-d6) δ: 13.22 (s,
1H, NH), 3.62–3.58 (m, 2H, SOCH2), 2.54–2.51 (m, 2H,
COCH2), 1.73–1.67 (m, 3H, cyclopentane–H), 1.62–1.58
(m, 2H, cyclopentane–H), 1.55–1.53 (m, 2H,
cyclopentane–H), 1.46–1.43 (m, 2H, cyclopentane–H),
1.21 (t, J = 7.3 Hz, 3H, CH3), 1.07–1.03 (t, J = 9.2 Hz,
2H, cyclopentane–CH2). 13C-NMR (126 MHz,
DMSO-d6) δ: 173.15, 163.02, 161.20, 50.20, 34.74,
3-Cyclopentyl-N-(5-(pentylsulfonyl)-1,3,4-thiadiazol-2-yl)
propanamide (7g).
White solid, yield 75%, mp 216.3–
217.1°С. 1H-NMR (400 MHz, DMSO-d6) δ: 13.25 (s,
1H, NH), 3.65–3.65–3.61 (m, 2H, SO2CH2), 2.58–2.54
(m, 2H, COCH2), 1.74–1.62 (m, 7H, cyclopentane–H,
CH2), 1.59–1.53 (m, 2H, cyclopentane–H), 1.52–1.44 (m,
2H, cyclopentane–H), 1.36–1.26 (m, 4H, 2CH2), 1.11–
1.06 (m, 2H, cyclopentane–CH2), 0.83 (t, J = 7.2 Hz, 3H,
CH3). 13C-NMR (101 MHz, DMSO-d6) δ: 173.08,
162.92, 161.62, 55.18, 34.67, 32.39, 31.06, 29.89, 25.13,
32.46, 31.12, 25.21, 7.52. ESI-MS m/z: 318.0 [M + H]+.
N-(5-(Allylsulfonyl)-1,3,4-thiadiazol-2-yl)-3-
22.20, 21.97, 14.08. ESI-MS m/z: 360.1 [M + H]+.
N-(5-(sec-Butylsulfonyl)-1,3,4-thiadiazol-2-yl)-3-
cyclopentylpropanamide (7c). White solid, yield 68%, mp
1
189.7–190.6°С. H-NMR (400 MHz, CDCl3) δ: 12.96 (s,
cyclopentylpropanamide (7h). White solid, yield 75%, mp
1H, NH), 5.94–5.83 (m, 1H, CH), 5.47 (d, J = 10.8 Hz,
1H, CH), 5.36 (d, J = 17.0 Hz, 1H, CH), 4.19 (d,
J = 7.4 Hz, 2H, SO2CH2), 2.81–2.77 (m, 2H, COCH2),
1.90–1.81 (m, 5H, cyclopentane–H), 1.66–1.62 (m, 2H,
cyclopentane–H), 1.56–1.53 (m, 2H, cyclopentane–H),
1.21–1.13 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, CDCl3) δ: 172.38, 164.29, 161.77, 126.61,
123.04, 60.05, 39.70, 35.68, 32.42, 31.30, 25.16. ESI-MS
1
210.1–210.4°С. H-NMR (500 MHz, CDCl3) δ: 12.94 (s,
1H, NH), 3.40–3.40–3.36 (m, 1H, SO2CH), 2.78–2.75
(m, 2H, COCH2), 2.17–2.13 (m, 2H, CH2), 1.83–1.79
(m, 5H, cyclopentane–H), 1.64–1.61 (m, 2H,
cyclopentane–H), 1.54–1.51 (m, 2H, cyclopentane–H),
1.44 (d, J = 6.9 Hz, 3H, CH3), 1.16–1.12 (m, 2H,
cyclopentane–CH2), 1.05 (t, J = 1.05 Hz, 3H, CH3). 13C-
NMR (126 MHz, CDCl3) δ: 172.46, 164.35, 161.68,
62.36, 39.78, 35.76, 32.48, 31.35, 25.22, 22.47, 12.56,
11.19. ESI-MS m/z: 346.1 [M + H]+.
m/z: 330.0 [M + H]+.
3-Cyclopentyl-N-(5-(propylsulfonyl)-1,3,4-thiadiazol-2-yl)
propanamide (7d). White solid, yield 54.6%, mp 185.4–
186.2°С. 1H-NMR (500 MHz, DMSO-d6) δ: 13.22 (s,
1H, NH), 3.60–3.57 (m, 2H, SOCH2), 2.54–2.51 (m, 2H,
COCH2), 1.73–1.65 (m, 5H, cyclopentane–H), 1.62–1.58
(m, 2H, CH2), 1.55–1.51 (m, 2H, cyclopentane–H), 1.48–
1.43 (m, 2H, cyclopentane–H), 1.06–1.04 (m, 2H,
cyclopentane–CH2), 0.93 (t, J = 7.4 Hz, 3H, CH3). 13C-
NMR (126 MHz, DMSO-d6) δ: 173.15, 163.01, 161.67,
56.85, 34.74, 32.46, 31.13, 25.21, 16.55, 12.93. ESI-MS
3-Cyclopentyl-N-(5-((2-methylbutyl)sulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7i). White solid, yield 64.6%,
mp 163.1–165.2°С. 1H-NMR (400 MHz, CDCl3) δ: 13.00
(s, 1H, NH), 3.53–3.48 (m, 1H, SO2CH), 3.34–3.29 (m,
1H, SO2CH), 2.80–2.77 (m, 2H, COCH2), 1.89–1.80 (m,
5H, cyclopentane–H), 1.66–1.62 (m, 2H, cyclopentane–
H), 1.57–1.50 (m, 4H, cyclopentane–H, CH2), 1.43–1.34
(m, 1H, CH), 1.21–1.16 (m, 2H, cyclopentane–CH2),
1.14 (d, J = 6.7 Hz, 3H, CH3), 0.92 (t, J = 7.4 Hz, 3H,
CH3). 13C-NMR (101 MHz, CDCl3) δ: 172.36, 164.06,
163.52, 61.41, 39.76, 35.68, 32.42, 31.27, 29.98, 29.35,
m/z: 332.1 [M + H]+.
3-Cyclopentyl-N-(5-(isopropylsulfonyl)-1,3,4-thiadiazol-2-yl)
propanamide (7e). White solid, yield 72.4%, mp 226.1–
1
25.15, 19.33, 10.76. ESI-MS m/z: 360.1 [M + H]+.
Ethyl 2-((5-(3-cyclopentylpropanamido)-1,3,4-thiadiazol-2-
228.5°С. H-NMR (400 MHz, CDCl3) δ: 13.05 (s, 1H,
NH), 3.67–3.57 (m, 1H, SO2CH), 2.81–2.77 (m, 2H,
COCH2), 1.88–1.80 (m, 5H, cyclopentane–H), 1.65–1.61
(m, 2H, cyclopentane–H), 1.56–1.52 (m, 2H,
cyclopentane–H), 1.48 (d, J = 6.9 Hz, 6H, CH3), 1.20–
1.11 (m, J = 15.1, 7.6 Hz, 2H, cyclopentane–CH2). 13C-
NMR (101 MHz, CDCl3) δ: 172.42, 164.36, 161.25,
56.49, 39.70, 35.69, 32.40, 31.30, 25.14, 15.43. ESI-MS
yl)sulfonyl)acetate (7j).
White solid, yield 89%, mp
1
176.8–178.4°С. H-NMR (500 MHz, CDCl3) δ: 12.99 (s,
1H, NH), 4.48 (s, 2H, SO2CH2), 4.23–4.19 (m,
J = 7.1 Hz, 2H, CH2CH3), 2.78–2.75 (m, 2H, COCH2),
1.87–1.79 (m, 5H, cyclopentane–H), 1.63–1.60 (m, 2H,
cyclopentane–H), 1.53–1.51 (m, 2H, cyclopentane–H),
1.25 (t, J = 7.1 Hz, 3H, CH3), 1.18–1.11 (m, 2H,
cyclopentane–CH2). 13C-NMR (126 MHz, CDCl3) δ:
172.50, 164.66, 162.00, 161.64, 63.15, 59.64, 39.75,
35.73, 32.47, 31.36, 25.22, 14.02. ESI-MS m/z: 376.0
m/z: 344.1 [M + H]+.
N-(5-(Butylsulfonyl)-1,3,4-thiadiazol-2-yl)-3-
cyclopentylpropanamide (7f).
White solid, yield 63.2%,
1
mp 183.3–184.3°С. H-NMR (400 MHz, DMSO-d6) δ:
13.25 (s, 1H, NH), 3.66–3.62 (m, 2H, SO2CH2), 2.58–
2.54 (m, 2H, COCH2), 1.79–1.71 (m, 3H, cyclopentane–
H), 1.66–1.62 (m, 4H, cyclopentane–H, CH2), 1.59–1.55
(m, 2H, cyclopentane–H), 1.50–1.45 (dd, J = 16.9,
5.3 Hz, 2H, cyclopentane–H), 1.39–1.35 (m, 2H, CH2),
1.11–1.06 (m, 2H, cyclopentane–CH2), 0.86 (t,
J = 7.4 Hz, 3H, CH3). 13C-NMR (101 MHz, DMSO-d6)
[M + H]+.
N-(5-(Benzylsulfonyl)-1,3,4-thiadiazol-2-yl)-3-
cyclopentylpropanamide (7k).
White solid, yield 67.3%,
mp 201.4–202.6°С. 1H-NMR (500 MHz, CDCl3) δ:
12.97 (s, 1H, NH), 7.36–7.32 (m, 3H, Ar–H), 7.26 (d,
J = 6.0 Hz, 2H, Ar–H), 4.69 (s, 2H, SO2CH2), 2.78–2.75
(m, 2H, COCH2), 1.89–1.79 (m, 5H, cyclopentane–H),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Zhang, W. Xu, K. Wei, H. Liu, Q. Yang, Q. Liu, L. Yang, Y. Luo, and W. Xue
Vol 000
1.66–1.60 (m, 2H, cyclopentane–H), 1.57–1.53 (m, 2H,
cyclopentane–H), 1.19–1.14 (m, 2H, cyclopentane–CH2).
13C-NMR (126 MHz, CDCl3) δ: 172.38, 164.53, 161.89,
131.16, 129.66, 129.22, 126.05, 62.07, 39.81, 35.78,
3-Cyclopentyl-N-(5-((4-methylbenzyl)sulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7p).
White solid, yield
59.8%, mp 210–211.2°С. 1H-NMR (500 MHz,
DMSO-d6) δ: 13.18 (s, 1H, NH), 7.10 (d, J = 15.7 Hz,
4H, Ar–H), 4.94 (s, 2H, SO2CH2), 2.52–2.49 (m, 2H,
COCH2), 2.25 (s, 3H, CH3), 1.72–1.68 (m, 3H,
cyclopentane–H), 1.57–1.53 (m, 4H, cyclopentane–H),
1.46–1.43 (m, 2H, cyclopentane–H), 1.04–1.02 (m, 2H,
cyclopentane–CH2). 13C-NMR (126 MHz, DMSO-d6) δ:
173.13, 163.18, 161.10, 138.87, 131.68, 129.69, 124.55,
61.09, 34.74, 32.45, 31.07, 25.20, 21.31. ESI-MS m/z:
32.52, 31.37, 25.26. ESI-MS m/z: 380.1 [M + H]+.
N-(5-((3-Cyanobenzyl)sulfonyl)-1,3,4-thiadiazol-2-yl)-3-
cyclopentylpropanamide (7l). White solid, yield 65%, mp
1
168.7–169.0°С. H-NMR (400 MHz, DMSO-d6) δ: 13.29
(s, 1H, NH), 7.88 (d, J = 7.1 Hz, 1H, Ar–H), 7.73 (s, 1H,
Ar–H), 7.62–7.59 (m, 2H, Ar–H), 5.17 (s, 2H, SO2CH2),
2.57–2.54 (m, 2H, COCH2), 1.72 (s, 3H, cyclopentane–
H), 1.63–1.62 (m, 7.8 Hz, 4H, cyclopentane–H), 1.49–
1.48 (d, J = 6.6 Hz, 2H, cyclopentane–H), 1.08 (s, 2H,
cyclopentane–CH2). 13C-NMR (101 MHz, DMSO-d6) δ:
173.15, 163.31, 160.49, 136.63, 135.21, 133.12, 130.39,
129.59, 118.69, 111.95, 60.25, 34.69, 32.38, 31.01,
394.1 [M + H]+.
3-Cyclopentyl-N-(5-((2-fluorobenzyl)sulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7q). White solid, yield 50%,
1
mp 205.6–206.1°С. H-NMR (500 MHz, DMSO-d6) δ:
13.23 (s, 1H, NH), 7.44–7.39 (m, 1H, Ar–H), 7.33 (t,
J = 7.6 Hz, 1H, Ar–H), 7.20–7.16 (m, 2H, Ar–H), 5.02
(s, 2H, SO2CH2), 2.54–2.51 (m, 2H, COCH2), 1.72–1.66
(m, 3H, cyclopentane–H), 1.60–1.56 (m, 2H,
cyclopentane–H), 1.55–1.50 (m, 2H, cyclopentane–H),
1.45–1.43 (m, 2H, cyclopentane–H), 1.07–1.01 (m, 2H,
cyclopentane–CH2). 13C-NMR (101 MHz, CDCl3) δ:
172.21, 170.30, 163.34, 162.49, 160.02, 132.70, 132.67,
131.24, 131.16, 124.63, 124.59, 115.81, 115.66, 115.60,
115.51, 56.30, 39.74, 35.68, 32.39, 31.32, 25.16. ESI-MS
25.13. ESI-MS m/z: 405.1 [M + H]+.
N-(5-((4-Cyanobenzyl)sulfonyl)-1,3,4-thiadiazol-2-yl)-3-
cyclopentylpropanamide (7m). White solid, yield 64.8%,
mp 218.4–219°С. 1H-NMR (500 MHz, DMSO-d6) δ:
13.23 (s, 1H, NH), 7.82 (d, J = 6.9 Hz, 2H, Ar–H), 7.46
(d, J = 7.0 Hz, 2H, Ar–H), 5.19 (s, 2H, SO2CH2), 2.52 (t,
J
= 7.5 Hz, 2H, COCH2), 1.68–1.61 (m, 3H,
cyclopentane–H), 1.60–1.56 (m, 2H, cyclopentane–H),
1.55–1.51 (m, 2H, cyclopentane–H), 1.45–1.43 (m, 2H,
cyclopentane–H), 1.04–1.02 (m, 2H, cyclopentane–CH2).
13C-NMR (126 MHz, DMSO-d6) δ: 173.19, 163.33,
160.65, 133.46, 132.95, 132.77, 118.95, 112.21, 60.80,
m/z: 398.0 [M + H]+.
3-Cyclopentyl-N-(5-((3-fluorobenzyl)sulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7r). White solid, yield 67%,
1
34.75, 32.45, 31.06, 25.20. ESI-MS m/z: 405.1 [M + H]+.
mp 195.4–196.2°С. H-NMR (400 MHz, DMSO-d6) δ:
13.25 (s, 1H, NH), 7.43–7.38 (m, 1H, Ar–H), 7.22 (t,
J = 8.6 Hz, 1H, Ar–H), 7.13 (t, J = 7.7 Hz, 2H, Ar–H),
5.10 (s, 2H, SO2CH2), 2.57–2.53 (m, 2H, COCH2), 1.77–
1.72 (m, 3H, cyclopentane–H), 1.65–1.57 (m, 4H,
cyclopentane–H), 1.51–1.46 (m, 2H, cyclopentane–H),
1.09–1.05 (m, 2H, cyclopentane–CH2). 13C-NMR
(101 MHz, DMSO-d6) δ: 173.15, 163.44, 163.29, 161.01,
160.68, 131.07, 130.98, 130.30, 130.22, 127.97, 127.94,
3-Cyclopentyl-N-(5-((2-methylbenzyl)sulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7n).
White solid, yield
57.4%, mp 196.5–197.1°С. 1H-NMR (400 MHz,
DMSO-d6) δ: 13.23 (s, 1H, NH), 7.25–7.17 (m, 2H, Ar–
H), 7.08–7.04 (m, 2H, Ar–H), 4.98 (s, 2H, SO2CH2),
2.58–2.57–2.53 (m, 2H, COCH2), 2.25 (s, 3H, CH3),
1.77–1.70 (m, 3H, cyclopentane–H), 1.65–1.60 (m, 2H,
cyclopentane–H), 1.58–1.56 (m, 2H, cyclopentane–H),
1.50–1.45 (m, 2H, cyclopentane–H), 1.10–1.06 (m, 2H,
cyclopentane–CH2). 13C-NMR (101 MHz, DMSO-d6) δ:
173.07, 163.15, 161.05, 138.17, 132.31, 129.98, 128.93,
128.85, 127.42, 61.34, 34.67, 32.39, 31.02, 25.13, 21.28.
118.56, 118.34, 116.42, 116.22, 60.61, 34.70, 32.38,
31.00, 25.13. ESI-MS m/z: 398.0 [M + H]+.
3-Cyclopentyl-N-(5-((4-fluorobenzyl)sulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7s).
White solid, yield
60.8%, mp 210.6–211.1°С. 1H-NMR (400 MHz,
DMSO-d6) δ: 13.23 (s, 1H, NH), 7.34–7.31 (m, 2H, Ar–
H), 7.23–7.18 (t, J = 8.9 Hz, 2H, Ar–H), 5.06 (s, 2H,
SO2CH2), 2.57–2.53 (m, 2H, COCH2), 1.77–1.69 (m,
3H, cyclopentane–H), 1.65–1.56 (m, 4H, cyclopentane–
H), 1.52–1.46 (m, 2H, cyclopentane–H), 1.10–1.05 (m,
2H, cyclopentane–CH2). 13C-NMR (101 MHz,
DMSO-d6) δ: 173.09, 164.13, 163.20, 161.69, 160.78,
133.96, 133.88, 124.03, 116.15, 115.93, 60.33, 34.68,
32.39, 30.99, 25.13. ESI-MS m/z: 398.0 [M + H]+.
ESI-MS m/z: 394.1 [M + H]+.
3-Cyclopentyl-N-(5-((3-methylbenzyl)sulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7o). White solid, yield 50%,
mp 179.4–180.1°С. 1H-NMR (400 MHz, CDCl3) δ:
12.79 (s, 1H, NH), 7.21–7.18 (m, 2H, Ar–H), 7.14 (s,
1H, Ar–H), 7.01 (d, J = 6.9 Hz, 1H, Ar–H), 4.66 (s, 2H,
SO2CH2), 2.78–2.75 (m, 2H, COCH2), 2.33 (s, 3H,
CH3), 1.88–1.81 (t, J = 9.5 Hz, 5H, cyclopentane–H),
1.66–1.61 (m, 2H, cyclopentane–H), 1.56–1.54 (m, 2H,
cyclopentane–H), 1.22–1.15 (m, 2H, cyclopentane–CH2).
13C-NMR (101 MHz, CDCl3) δ: 172.27, 164.36, 162.00,
138.99, 131.85, 130.37, 128.92, 128.08, 125.70, 62.00,
39.73, 35.69, 32.44, 31.28, 25.18, 21.34. ESI-MS m/z:
394.1 [M + H]+.
3-Cyclopentyl-N-(5-((4-(trifluoromethyl)benzyl)sulfonyl)-
1,3,4-thiadiazol-2-yl)propanamide (7t).
White solid, yield
83.3%, mp 229.5–230.1°С. 1H-NMR (400 MHz,
DMSO-d6) δ: 13.26 (s, 1H, NH), 7.76 (d, J = 8.1 Hz, 2H,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2019
Synthesis and Evaluation of 1,3,4-Thiadiazole Derivatives Containing
Cyclopentylpropionamide as Potential Antibacterial Agent
Ar–H), 7.53 (d, J = 8.0 Hz, 2H, Ar–H), 5.22 (s, 2H,
SO2CH2), 2.57–2.53 (m, 2H, COCH2), 1.77–1.72 (m,
4H, cyclopentane–H), 1.61–1.59 (m, 3H, cyclopentane–
H), 1.58–1.56 (m, 2H, cyclopentane–H), 1.50–1.45 (m,
2H, cyclopentane–H), 1.10–1.07 (m, 2H, cyclopentane–
CH2). 13C-NMR (101 MHz, DMSO-d6) δ: 173.10,
163.26, 160.69, 132.63, 132.55, 131.86, 129.91,
125.92,125.88, 123.15, 60.61, 34.67, 32.38, 31.00, 25.12.
ESI-MS m/z: 448.0 [M + H]+.
Curative activity of compound 7a against Xoo in vivo.
Compound 7a and commercial controls (thiodiazole
copper and bismerthiazol) were formulated in
drug-containing solutions at 200 μg/mL concentration
containing 0.1% Tween. After planting “Fengyou
xiangzhan” rice seed for approximately one and a half
month, sterile scissors were used to cut the leaf tip by 1
to 2 cm, and the wound was soaked in the bacterial
solution for 10 s. At the same time, the clear water
control and bacterial liquid control without medicament
were set. On the next day, a drug solution with
200 μg/mL concentration was sprayed on the surface of
the rice leaf until a droplet dripped. A total of 20 rice
seedlings were treated for each treatment, which was
repeated three times, and the incidence was evaluated
14 days after application. The length of lesions in rice
leaves was recorded, and the disease index and control
effect were calculated.
Protective activity of compound 7a against Xoo in vivo.
The protection activity against potted plants of Xoo
was assessed under greenhouse conditions. Compound
7a and commercial controls (thiodiazole copper and
bismerthiazol) were formulated in drug-containing
solutions at 200 μg/mL concentration containing 0.1%
Tween. After planting “Fengyouxiangzhan” rice seeds
for approximately one and a half month, the drug-
containing solution was sprayed on the surface of rice
leaves until droplets dripped. On the next day, sterile
scissors were used to cut the leaf tip by 1 to 2 cm, and
the wound was soaked in the bacterial solution for 10 s.
At the same time, the clear water control and bacterial
liquid control without the drug were set. Inoculated rice
plants were grown in a greenhouse (28°C and 61%
relative humidity). A total of 20 rice seedlings were
treated for each treatment, which was repeated three
times, and the incidence was evaluated 14 days after
application. The length of lesions in rice leaves was
recorded, and the disease index and control effect were
calculated.
3-Cyclopentyl-N-(5-((3-methoxybenzyl)sulfonyl)-1,3,4-
thiadiazol-2-yl)propanamide (7u).
White solid, yield
1
85.3%, mp 164.2–164.6°С. H-NMR (400 MH, CDCl3)
δ: 12.55 (s, 1H, NH), 7.22 (d, J = 7.8 Hz, 1H, Ar–H),
6.91–6.79 (m, 3H, Ar–H), 4.67 (s, 2H, SO2CH2), 3.78 (s,
3H, OCH3), 2.76–2.73 (m, 2H, COCH2), 1.83–1.82 (m,
5H, cyclopentane–H), 1.54 (s, 2H, cyclopentane–H), 1.54
(s, 2H, cyclopentane–H), 1.17 (s, 2H, cyclopentane–
CH2). 13C-NMR (101 MHz, CDCl3) δ: 172.18, 164.24,
161.88, 159.92, 130.08, 127.25, 123.28, 116.61, 115.17,
61.97, 55.35, 39.69, 35.66, 32.44, 31.24, 25.17. ESI-MS
m/z: 410.1 [M + H]+.
In vitro antibacterial activity test.
According to the
turbidimeter test, the target compounds were evaluated
in vitro antibacterial activity against Rs, Xac, and Xoo
[34]. Dimethyl sulfoxide in sterile distilled water served
as the blank control, and commercial antibacterial agents,
thiodiazole copper and bismerthiazol, were assayed
together as the positive control under the same conditions.
Nutrient broth (NB) medium (1 L of distilled water, 10 g
of glucose, 3 g of beef extract, 5 g of peptone, and 1 g of
yeast powder, pH 7.0–7.2) was sterilized. Then, NB
(4 mL) and a test compound or commercial bactericide
solution (1 mL) were added to a 15 mL tube, and final
active ingredient concentrations of 100 and 50 μg/mL
were obtained with the addition of bacterial solution. The
tubes were incubated for 24–48 h in a constant
temperature shaker (180 r.p.m., 28 1°C). The optical
density (OD) value (OD595) of the bacterial solution
treated with each concentration of the drug was measured
when the optical density (OD595) of the blank control
group was 0.6 to 0.8 on a microplate reader (Model 680,
Bio-Rad, Hercules, CA). Using the following formula to
calculate the inhibition rate I (%), A represents the
calibration of absorbance values (OD595) of the untreated
The control effect of the curative and protective
activities was calculated according to the following
formula, where A represents the disease index of the
negative control group and B represents the disease index
of the treatment group.
NB medium, and
B represents the calibration of
absorbance values (OD595) of the treated NB medium.
Control effect ð%Þ ¼ ðΑ ꢀ ΒÞ=Α·100:
Inhibition rate Ι ð%Þ ¼ ðΑ ꢀ ΒÞ=Α·100:
EC50 values were tested on three separate growth
inhibition assays and calculated in IBM SPSS STATISTICS.
The disease marker was graded as follows: level 0, no
disease; level 1, the lesions occupy ≤15% of the leaf
area; level 2, the lesions accounted for 16–30% of leaf
area; level 3, the lesions accounted for 31–50% of leaf
area; level 4, the lesions accounted for 51–75% of leaf
area; and level 5, the lesions accounted for more than
76% of leaf area.
In vivo antibacterial activity test.
We used Schaad’s
standard leaf clipping method to evaluate the curative and
protection activities against Xoo in vivo with three
replications [35].
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Zhang, W. Xu, K. Wei, H. Liu, Q. Yang, Q. Liu, L. Yang, Y. Luo, and W. Xue
Vol 000
[14] Liu, H. Y.; Wang, H. X.; Li, X.; Wu, Z.; Li, C. W.; Liu, Y. M.;
Li, Y.; Chen, B. Q. Med Chem Res 2018 27, 1929.
[15] Charitos, G.; Trafalis, D. T.; Dalezis, P.; Potamitis, C.; Sarli,
V.; Zoumpoulakis, P.; Camoutsis, C. Arab J Chem 2016.
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Acknowledgments. The authors gratefully acknowledge the
financial support of the National Natural Science Foundation of
China (nos. 31760532 and 21262009) and Guizhou S&T Project
(no. 20113071).
[17] Shafique, M.; Hameed, S.; Naseer, M. M.; Al-Masoudi, N. A.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet