Design, Synthesis and Biological Evaluation of N-((2-phenyloxazol-4-yl)methyl) Pyrimidine Carboxamide Derivatives as Potential Fungicidal Agents

Article abstract of DOI:10.1515/hc-2020-0117

Twelve N-((2-phenyloxazol-4-yl)methyl) pyrimidine carboxamide derivatives were designed, synthesized, and characterized by 1H NMR, 13C NMR, and HRMS. The fungicidal activities of these new compounds against Sclerotinia sclerotiorum, Botrytis cinereal, and Colletotrichum fragariae were evaluated. The results indicated that compounds 5b, 5f, and 5g displayed potential fungicidal activities against tested fungi, especially 5f exhibited IC50 value of 28.9 mg/L against S. sclerotiorum. Moreover, the compounds 5f and 5g showed IC50 values of 54.8 mg/L and 62.2 mg/L against C. fragariae respectively, which shows that they were more active than the commercial fungicide hymexazol. The superficial structure-activity relationships were discussed, which may be of benefit for the development of fungicides and discovery of novel fungicides.

Full text of DOI:10.1515/hc-2020-0117

Heterocycl. Commun. 2020; 26: 185–191
Research Article
Open Access
DDaenlisngigHunan,gS, SyhunmtinhZehesnigsanadnYodng-BXiainoClhoenggi*cal Evaluation of
N-((2-phenyloxazol-4-yl)methyl) Pyrimidine
Carboxamide Derivatives as Potential Fungicidal
Agents
https://doi.org/10.1515/hc-2020-0117
Received October 14, 2020; accepted November 28, 2020.
Abstract: Twelve N-((2-phenyloxazol-4-yl)methyl) pyri- Introduction
midine carboxamide derivatives were designed, synthe-
sized, and characterized by 1H NMR, 13C NMR, and HRMS. Plant diseases are one of the main causes of crops reduc-
The fungicidal activities of these new compounds against tion, around 80% of which result from fungi infections
Sclerotinia sclerotiorum, Botrytis cinereal, and Colletotri- [1,2]. Furthermore, human health is harmed because
chum fragariae were evaluated. The results indicated that of the mycotoxins that are produced by the fungi [3,4].
compounds 5b, 5f, and 5g displayed potential fungicidal Undoubtedly, rational application of fungicides is an
activities against tested fungi, especially 5f exhibited IC50 effective method for fungal control. However, most fungi
value of 28.9 mg/L against S. sclerotiorum. Moreover, the have developed resistances or cross-resistances to the
compounds 5f and 5g showed IC50 values of 54.8 mg/L commercial fungicides [5]. Therefore, development and
and 62.2 mg/L against C. fragariae respectively, which discovery of novel fungicides with high-efficiency and
shows that they were more active than the commercial lower toxicity is tremendously necessary and needed
fungicide hymexazol. The superficial structure-activity with great urgency.
relationships were discussed, which may be of benefit
The oxazole skeleton is of extraordinary importance in
for the development of fungicides and discovery of novel the design of active fungicidal molecules. Recently, lots of
fungicides.
oxazole derivatives with potential fungicidal activity have
been discovered [6-9]. Studies suggest that the oxazole
Keywords: Oxazole derivative, Synthesis, Fungicidal acti- derivatives display a broad spectrum of antifungal acti-
vities, Structure-activity relationship
vity. Moreover, there are many oxazole derivatives being
developed for the commercial fungicides (Figure 1a), such
as famoxadone [10], hymexazol [11], and oxadixyl [12].
On the other hand, the pyrimidine ring is a remarkable
moiety in various bioactive molecules including anti-
fungal, antimicrobial, anticancer and anti-inflammatory
agents [13]. In particular, pyrimidine derivatives hold
a pivotal position in the structure of fungicides design,
*Corresponding author: Yong-Xian Cheng, School of Pharmaceutical
Sciences, Shenzhen University Health Science Center, Shenzhen
518060, China; E-mail: yxcheng@szu.edu.cn
Danling Huang, School of Pharmaceutical Sciences, Shenzhen
University Health Science Center, Shenzhen 518060, China
Shumin Zheng, School of Pharmaceutical Sciences, Shenzhen
University Health Science Center, Shenzhen 518060, China
Open Access. © 2020 Huang et al., published by De Gruyter.ꢀ
Attribution alone 4.0 License.
ꢀThis work is licensed under the Creative Commons

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186ꢁ
D. Huang et al.: Design, Synthesis and Biological Evaluation of N-((2-phenyloxazol-4-yl)methyl) Pyrimidine
Figure 1ꢀThe design of fungicidal 2-aryl-oxazole derivatives containing pyrimidine
and have yielded the commercial products of pyrimetha- Result and discussion
nil [14], fenarimol [15], mepanipyrim [16], and ferimzone
[17] (Figure 1b). Literature showed that the introduction of The target compounds, N-((2-(4-substituted-phenyl)oxa-
a pyrimidine fragment was beneficial to the improvement zol-4-yl)methyl)pyrimidine carboxamides (5a-5l) were
of fungicidal activities of compounds [18-20]. Toshihiro synthesized as outlined in Scheme 1. Initially, the ske-
et al. [21] gave the systematic structure-activity relation- leton of the oxazole ring was built by a Bredereck reac-
ship (SAR) of pyrimidine derivatives. They found that tion [22]. The 2-aryl-4-chloromethyl oxazole (2a-2d) was
the pyrimidine ring introduced the same substituents at obtained via reaction between 1,3-dichloroacetone and
o
the different positions and influenced the bioactivities amide (1a-1d) and heating at 130 C. The Gabriel reac-
of the compounds remarkably. Inspired by this work, tion [23] was carried out to shift 2a-2d to the key inter-
formamide derivatization on different positions of pyrimi- mediates 4a-4d. In brief, potassium phthalimide was
dine was considered in our design strategy. In our effort reacted with the corresponding 4-chloromethyl oxazole
to seek novel compounds with potential fungicidal acti- (2a-2d) in N,N-dimethylformamide (DMF) at 80 oC. Then,
vities, we tried to use a molecular hybridization strategy these synthesized phthalimide derivates (3a-3d) were
to combine the active fragment oxazole and pyrimidine further treated with hydrazine hydrate in ethanol at
via an amido bond (Figure 1c), in which R was chosen as reflux temperature to result in the corresponding (2-aryl-
a hydrogen atom, methyl, methoxyl, or trifluoromethyl oxazol-4-yl)methanamine. Afterwards, amine hydro-
and Ar was fixed as 2 - pyrimidinyl, 4 – pyrimidinyl or 5 – chloride derivatives 4a-4d were generated by addition
pyrimidinyl. Herein, we report the synthesis of 12 pyrimi- of concentrated hydrochloric acid to (2-aryl-oxazol-4-yl)
dine amide derivatives containing 2-phenyl-oxazole and methanamine.
their fungicidal activities against three fungi, Sclerotinia
Finally, condensation reaction between 4a-4d and
sclerotiorum, Botrytis cinereal, and Colletotrichum fraga- pyrimidine carboxylic acid was carried out in the pre-
riae, which are known as the main pathogenic fungi in sence of 2-(7-Azabenzotriazol-1-yl)-N,N,N’,N’-tetramethy-
agriculture. Furthermore, the apparent SAR of these com- luronium hexafluorophosphate (HATU) to obtain target
pounds were discussed.
compounds 5a-5l, whose structures were identified by 1H

D. Huang et al.: Design, Synthesis and Biological Evaluation of N-((2-phenyloxazol-4-yl)methyl) Pyrimidineꢁ
ꢁ187
NMR, 13C NMR, and HRMS as detailed in the experimental cinerea at 100 mg/L. In addition, 5f and 5g showed similar
section. The final step of the synthesis gave satisfactory effects against C. fragariae to the commercial product
yields (≥ 80%) and the overall yield of the synthesis route hymexazol. Finally, as shown in Table 2, the IC50 values of
reported here was over 50%, which demonstrated that the the better bioactive compounds (5b, 5f and 5g) were given.
synthesis pathway shown in Scheme 1 is reasonable and It revealed that 5f (54.8 mg/L) and 5g (62.2mg/L) display
available.
lower IC50 value against C. fragariae than that of hymexa-
The structures and fungicidal activities against zol (148.9mg/L).
S. sclerotiorum, B. cinereal, and C. fragariae were shown in
The superficial structure-activity relationship presen-
Table 1. All target compounds were screened at three con- ted a general trend. On the basis of the bioassay data, the
centrations including 100 mg/L, 50 mg/L, and 30 mg/L. substituents R and Ar reflected a momentous relationship
As a result, 5f and 5g showed better fungicidal activi- with the activities. When Ar remained constant, the influ-
ties against the three test fungi (Figure 2). In detail, for ence of R on the fungicidal activities showed a regular
S. sclerotiorum, 5f, 5g, 5j displayed over 60% inhibition change. The fungicidal activities of target compounds
rate at the concentration of 100 mg/L. In particular, 5f is enhanced when the R is a CF3 rather than any other
displayed 45.6% inhibition rate against S. sclerotiorum substituent. Taking the assay concentration of 100 mg/L
at 30 mg/L, while 5g and 5j showed less activities (13.0% for example, compound 5f (75.6% inhibition rates) is more
and 28.7%) at the equivalent concentration. On the other active than 5e (69.1% inhibition rates), 5g (39.1% inhibition
hand, 5f and 5g exhibited over 50% inhibition against B. rates), or 5h (no effect) against S. sclerotiorum. Ordinarily,
Scheme 1ꢂSynthesis The synthesis route of a compound library based on oxazole derivatives as building blocks 5a-5i. Reagents and
conditions: i) 1,3-dichloroacetone, neat, 130 oC; ii) Potassium phthalimide, DMF, 80 oC; iii) Hydrazine hydrate, EtOH, reflux, then 37% HCl,
rt; iv) Pyrimidine carboxylic acid, HATU, Et3N, DMAP, DCM, 0 oC and then room temperature
Table 1ꢂ Inhibition ratio(%) of compounds 5a-5l and hymexazol against S. sclerotiorum, B. cinerea, and C. fragariae
Compound
Ar
R
S. Sclerotiorum (mg/L)
B. Cinerea (mg/L)
50
C. Fragariae (mg/L)
50 100
30
50
100
30
100
30
a
5a
5b
5c
5d
5e
5f
A1
A1
A1
A1
A2
A2
A2
A2
A3
A3
A3
A3
H
CF3
-
-
-
-
5.80
18.36
2.42
6.8
12.56
38.65
3.86
-
19.59
29.73
13.51
-
19.92
43.24
25.00
6.3
24.32
57.43
52.03
30.8
-
4.78
4.78
3.7
5.22
5.22
13.04
-
20.27
10.14
-
OCH3
CH3
H
-
-
10.0
-
7.9
3.04
18.26
66.09
67.83
19.8
19.13
50.87
12.17
8.9
39.13
75.65
69.13
17.2
10.14
38.16
10.63
13.3
-
18.84
49.76
31.40
17.2
6.76
9.18
3.38
-
27.05
53.14
51.69
28.6
7.73
29.95
8.70
12.16
29.05
23.65
16.3
10.14
10.81
18.92
-
14.86
45.27
48.65
22.9
10.81
17.57
17.57
-
CF3
45.65
5g
5h
5i
OCH3
CH3
H
13.04
-
-
34.78
62.17
28.26
4.9
13.51
37.16
21.62
-
5j
CF3
OCH3
CH3
28.70
16.91
4.35
-
5k
5l
-
-
14.8
82.2
6b
88.5
92.8
100
72.4
78.9
38.8
36.9
44.6
ameans no effect. bHymexazol.

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188ꢁ
D. Huang et al.: Design, Synthesis and Biological Evaluation of N-((2-phenyloxazol-4-yl)methyl) Pyrimidine
Table 2ꢂIC50 values of the target compounds against S. sclerotiorum, B. cinerea, and C. fragariae
Compound
S. sclerotiorum
B. cinerea
C. fragariae
IC50 (mg/L) Regression
equation
R2
IC50
(mg/L)
Regression
equation
R2
IC50
(mg/L)
Regression
equation
R2
5b
92.6
28.9
40.0
10.4
y=0.0061x
+0.1139
y=0.0073
+0.1792
y=0.0065x
+0.1533
y=0.0072x
+0.4217
0.780
0.845
0.654
0.642
146.0
51.7
116.8
4.4
y=0.0038x
+0.0378
y=0.0051x
+0.1596
y=0.004x
+0.0664
y=0.003x
+0.575
0.992
0.755
0.459
0.774
118.8
y=0.004xc
+0.0968
y=0.0049x
+0.1851
c0.0053x
+0.116
0.971
0.941
0.832
0.908
5f
54.8
5g
62.2
Hymexazol
148.9
y=0.0038x
+0.0619
Figure 2ꢂThe fungicidal efficacy of 5f and 5g
the influence of R on improved activity may be concluded
as follows: CF3 > OCH3 > H > CH3. In addition, when R is
kept invariant, modification of the Ar moiety from A3 and
A1 to A2 group increased the fungicidal activity evidently.
For example, the fungicidal activities against S. sclerotio-
rum are correlated as follows: 5e > 5i > 5a, 5f > 5j > 5b, and
5g > 5h > 5c.
Experimental Section
Synthesis and characterization
Melting points (m.p.) were measured on a MP450 mel-
ting-point apparatus (Shandong Nanon Instrument LTD,
CITY, China). The NMR spectra were recorded on a Bruker
AV-500 spectrometer (Bruker, Karlsruhe, Germany) with
TMS as an internal standard. HRESIMS was measured by
a Shimazu LC-20AD AB SCIEX triple TOF 5600+ MS spec-
trometer (Shimadzu Corporation, Tokyo, Japan). Column
chromatography was performed using 200-300 mesh
silica gels. The solvents and reagents were dried prior to
use. The general synthetic methods for compounds 5a-5l
are detailed in Scheme 1 and brief procedures are shown
below. Each target compound was identified and verified
by 1H NMR, 13C NMR, and HRESIMS.
Conclusion
In this paper, we synthesized and investigated N-((2-phe-
nyloxazol-4-yl)methyl) pyrimidine carboxamide deriva-
tives in vitro for their fungicidal activities against three
fungi, namely S. sclerotiorum, B. Cinerea, and C. fragariae.
It was noted that compounds 5f and 5g showed fungici-
dal activities against these three fungi. Especially, 5f and
5g displayed lower IC50 values than hymexazol (a posi-
tive control) against C. fragariae. With these findings, the
apparent structure–activity relationships were discussed. Synthesis of 4-(chloromethyl)-2-arlyloxazole (2a) and its
Our current study indicated that the present target com-
pounds should be worthwhile for further study as the
analogues (2b-2d)
lead compounds in the search for discovering potential A mixture of benzamide (1.81 g, 15 mmol) and 1,3-dichlo-
fungicides. roacetone (1.9 g, 17 mmol) was ground thoroughly. Then

D. Huang et al.: Design, Synthesis and Biological Evaluation of N-((2-phenyloxazol-4-yl)methyl) Pyrimidineꢁ
ꢁ189
the mixture was heated to liquation and the reaction tem- to obtain blown oil. Then the oil was dissolved in 10 mL
perature was kept at 130 oC for 4 h. Once cooled to room acetone, then added 0.5 mL concentrated hydrochloric
temperature, 150 mL EA was poured into the product acid to precipitate a large amount of solid. The precipitate
and it was washed twice with saturated Na2CO3 solution. was separated by filtration and washed twice with 20 mL
The EA layer was dried over Na2SO4, filtered and evapo- acetone, dried in vacuum to afford 4a as white solid (2.4 g,
rated. The residue was purified by chromatography on a 88% yields for two steps). The analogues (4b-4d) could be
silica gel column using petroleum ether (PE) and ethyl synthesized by the method similar to that described in the
acetate (EA) as the eluents to afford 2a as a white powder synthesis of 4a.
2.6 g (90% yield). The analogues (2b-2d) could be syn-
(2-Phenyloxazol-4-yl)methanamine hydrochlo-
1
thesized by the method similar to that described in the ride (4a): White solid; 88% yield; H NMR (600 MHz,
synthesis of 2a.
DMSO-d6) δ 8.59 (s, 3H), 8.30 (s, 1H), 8.09 – 7.87 (m, 2H),
4-(Chloromethyl)-2-phenyloxazole (2a): White 7.66 – 7.41 (m, 3H), 4.03 (d, J = 0.8 Hz, 2H). 13C NMR (150
1
solid; 90% yield; H NMR (600 MHz, CDCl3) δ 8.02 (dd, MHz, DMSO-d6) δ 161.4, 138.8, 135.8, 131.5, 129.8, 126.9,
J = 6.7, 3.0 Hz, 2H), 7.67 (s, 1H), 7.58 – 7.35 (m, 3H), 4.56 126.4, 34.7.
(s, 2H). 13C NMR (150 MHz, CDCl3) δ 162.3, 138.8, 136.2,
(2-(4-(Trifluoromethyl)phenyl)oxazol-4-yl)metha-
130.7, 128.8, 127.0, 126.5, 37.1.
namine hydrochloride (4b): Brown solid; 73% yield ;1H
4-(Chloromethyl)-2-(4-(trifluoromethyl)phenyl) NMR (600 MHz, DMSO-d6) δ 8.68 (s, 3H), 8.40 (s, 1H), 8.19
1
oxazole (2b): White solid; 85% yield; H NMR (500 (d, J = 8.1 Hz, 2H), 7.94 (d, J = 8.3 Hz, 2H), 4.05 (q, J = 5.7 Hz,
MHz, CDCl3) δ 8.16 (d, J = 8.1 Hz, 2H), 7.76 (s, 1H), 7.72 (d, 2H). 13C NMR (150 MHz, DMSO-d6) δ 160.0, 139.7, 136.2,
J = 8.3 Hz, 2H), 4.59 (d, J = 0.8 Hz, 2H).13C NMR (125 MHz, 131.07 (q, J = 32.0 Hz), 130.4, 127.2, 126.80 (q, J = 3.6 Hz),
CDCl3) δ 160.9, 139.3, 136.9, 132.31 (q, J = 32.7 Hz), 130.1, 124.32 (q, J = 272.3 Hz), 34.6.
126.8, 125.85 (q, J = 3.8 Hz), 124.8, 122.7, 36.8.
(2-(4-Methoxyphenyl)oxazol-4-yl)methanamine
4-(Chloromethyl)-2-(4-methoxyphenyl)oxazole hydrochloride (4c): White solid; 85% yield; 1H NMR (600
(2c): White solid; 87% yield; 1H NMR (600 MHz, CDCl3) MHz, DMSO-d6) δ 8.59 (s, 3H), 8.21 (s, 1H), 8.08 – 7.81 (m,
δ 8.10 – 7.87 (m, 1H), 7.66 (t, J = 0.8 Hz, 1H), 7.08 – 6.79 2H), 7.13 – 7.04 (m, 2H), 3.99 (s, 2H), 3.83 (s, 3H).13C NMR
(m, 1H), 4.57 (d, J = 0.9 Hz, 2H), 3.86 (s, 2H). 13C NMR (150 (150 MHz, DMSO-d6) δ 161.8, 161.5, 138.0, 135.5, 128.2, 119.5,
MHz, CDCl3) δ 162.5, 161.6, 138.5, 135.6, 128.2, 119.8, 114.2, 115.2, 55.9, 34.7.
55.4, 37.2.
(2-(p-Tolyl)oxazol-4-yl)methanamine hydrochlo-
1
4-(Chloromethyl)-2-(p-tolyl)oxazole (2d): White ride (4d): White solid; 82% yield; H NMR (600 MHz,
1
solid; 92% yield; H NMR (500 MHz, CDCl3) δ 7.93 (d, DMSO-d6) δ 8.58 (brs, 3H), 8.25 (s, 1H), 7.88 (d, J = 8.2 Hz,
J = 8.2 Hz, 2H), 7.68 (s, 1H), 7.26 (d, J = 8.0 Hz, 2H), 4.57 2H), 7.38 (d, J = 8.0 Hz, 2H), 4.01 (s, 2H), 2.38 (s, 3H). 13C
(d, J = 0.7 Hz, 2H), 2.40 (s, 3H). 13C NMR (125 MHz, CDCl3) NMR (150 MHz, DMSO-d6) δ 161.6, 141.4, 138.4, 135.6, 130.3,
δ 162.6, 141.1, 138.6, 135.9, 130.0, 129.5, 129.3, 126.5, 124.3, 126.4, 124.3, 34.7, 21.5.
37.2, 21.5.
Synthesis of N-((2-phenyloxazol-4-yl)methyl)pyrimidine-
2-carboxamide (5a) and its analogues (5b-5i)
Synthesis of 4-(aminomethyl)-2-arlyl oxazole (4a) and its
analogues (4b- 4d)
To a solution of pyrimidine-2-carboxamide (58.5 mg,
To a solution of 2a (2.6 g, 13.5 mmol) in 30 mL DMF was 0.48 mmol), Et3N (202 mg, 2.0 mmol), HATU (273.6 mg,
added potassium phthalimide (3.0g, 16.2mmol) in por- 0.72 mmol) and 4-dimethylaminopyridine (DMAP, 87.8 mg,
o
tions. After the mixture was stirred at 80 C for 5 h, the 0.72 mmol) in 10 mL dichloromethane (DCM), 4a (100 mg,
o
mixture was poured into ice water and the precipitate 0.48 mmol) was added under 0–5 C and kept stirring for
was collected by filtration and washed with water. 3a was 30 minutes. Then the mixture was stirred at ambient tem-
obtained as blown solid. Then 3a was mixed with 150 mL perature for 5 h. The reaction mixture was poured into
ethanol and hydrazine hydrate (50%, 5.2 g, 53.0 mmol). saturated NH4Cl aqueous solution (10 mL). The organic
After 5 h under reflux, the precipitate was separated by layer was washed twice with 5 mL saturated sodium
filtration and the solvent of filtrate was removed under chloride solution and dried over Na2SO4 and evaporated.
reduced pressure. The mixture was poured into ice water The residue was recrystallized from ethanol to afford 5a
and the aqueous phase was extracted with EA. The as a white powder (123.6 mg, 92% yield). The derivatives
organic layer was washed twice with water and dried over (5b-5i) could be synthesized by the method similar to that
Na2SO4, filtered, and concentrated under reduced pressure described in the synthesis of 5a.

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D. Huang et al.: Design, Synthesis and Biological Evaluation of N-((2-phenyloxazol-4-yl)methyl) Pyrimidine
N-((2-phenyloxazol-4-yl)methyl)pyrimidine- 35.5. HRMS m/z calcd for C16H11F3N4O2 (M-H)- 347.0761;
2-carboxamide (5a): White solid; 92% yield; m.p. 145 - Found 347.0758.
146 °C; 1H NMR (500 MHz, CDCl3) δ 8.89 (d, J = 4.9 Hz, 2H),
N-((2-(4-methoxyphenyl)oxazol-4-yl)methyl)
8.07 – 8.00 (m, 3H), 7.72 (s, 1H), 7.46 – 7.43 (m, 3H), 4.69 pyrimidine-4-carboxamide (5g): White solid; 87%
(d, J = 5.8 Hz, 2H). 13C NMR (125 MHz, CDCl3) δ 162.3, 162.1, yield; m.p. 127 - 129 °C H NMR (500 MHz, CDCl3) δ 9.25
1
157.5, 157.5, 138.2, 135.8, 130.5, 128.8, 127.3, 126.4, 122.6, 35.9. (d, J = 1.2 Hz, 1H), 8.98 (d, J = 5.0 Hz, 1H), 8.48 (brs, 1H),
HRMS m/z calcd for C15H12N4O2 (M-H)- 279.0887; Found 8.13 (dd, J = 5.0, 1.3 Hz, 1H), 8.07 – 7.87 (m, 2H), 7.65 (s, 1H),
279.0887.
7.08 – 6.79 (m, 2H), 4.63 (d, J = 5.8 Hz, 2H), 3.86 (s, 3H).
N-((2-(4-(trifluoromethyl)phenyl)oxazol-4-yl) 13C NMR (125 MHz, CDCl3) δ 162.7, 162.3, 161.5, 159.2, 157.8,
methyl)pyrimidine-2-carboxamide (5b): White solid; 156.1, 137.8, 135.1, 128.1, 120.0, 118.6, 114.2, 55.4, 35.7. HRMS
90% yield ; m.p. 139 - 140 °C; 1H NMR (500 MHz, CDCl3) δ m/z calcd for C16H14N4O3 (M-H)- 309.0993; Found 309.0989.
8.89 (d, J = 4.9 Hz, 2H), 8.15 (d, J = 8.2 Hz, 2H), 7.78 (s, 1H),
N-((2-(p-tolyl)oxazol-4-yl)methyl)pyrimidine-
7.72 (d, J = 8.3 Hz, 2H), 7.46 (t, J = 4.9 Hz, 1H), 4.70 (d, J = 4-carboxamide(5h):Whitesolid;80%yield;m.p.157-159°C
5.9 Hz, 2H). 13C NMR (125 MHz, CDCl3) δ 162.3, 160.6, 157.5, 1H NMR (600 MHz, DMSO-d6) δ 9.30 (t, J = 5.9 Hz, 1H), 8.97
157.5, 138.8, 136.7, 126.7, 130.4, 25.9, 125.8, 122.7, 35.8. HRMS (d, J = 4.9 Hz, 2H), 8.00 (s, 1H), 7.84 (d, J = 8.2 Hz, 2H),
m/z calcd for C16H11F3N4O2 (M-H)- 347.0761; Found 347.0759. 7.69 (t, J = 4.9 Hz, 1H), 7.33 (d, J = 8.0 Hz, 2H), 4.46 (dd, J =
N-((2-(4-methoxyphenyl)oxazol-4-yl)methyl) 6.0, 0.8 Hz, 2H), 2.35 (s, 3H). 13C NMR (150 MHz, DMSO-d6)
pyrimidine-2-carboxamide (5c): White solid; 93% yield; δ 162.9, 161.2, 158.3, 158.2, 141.0, 139.7, 136.6, 130.2, 126.3,
1
m.p. 59 - 60 °C; H NMR (500 MHz, CDCl3) δ 8.88 (d, J = 124.7, 123.6, 35.9, 21.5. HRMS m/z calcd for C16H14N4O2 (M-H)-
4.8 Hz, 2H), 7.96 (d, J = 8.7 Hz, 2H), 7.67 (s, 1H), 7.45 (d, J = 293.1044; Found 293.1047.
4.8 Hz, 1H), 6.96 (d, J = 8.7 Hz, 2H), 4.66 (d, J = 5.7 Hz,
N-((2-phenyloxazol-4-yl)methyl)pyrimidine-
3H), 3.86 (s, 3H). 13C NMR (125 MHz, CDCl3) δ 162.3, 162.2, 5-carboxamide(5i):Whitesolid;83%yield;m.p.134-136°C
161.5, 157.5, 157.5, 137.9, 135.2, 128.1, 122.6, 120.1, 114.2, 76.8, 1H NMR (500 MHz, CDCl3) δ 9.32 (s, 1H), 9.16 (s, 1H), 8.00
55.4, 35.9. HRMS m/z calcd for C16H14N4O3 (M-H)- 309.0993; (dd, J = 6.6, 2.9 Hz, 2H), 7.73 (s, 1H), 7.47 (dd, J = 4.9, 1.6 Hz,
Found 309.0991.
3H), 7.22 (s, 1H), 4.63 (d, J = 5.4 Hz, 2H). 13C NMR (125 MHz,
N-((2-(p-tolyl)oxazol-4-yl)methyl)pyrimidine- CDCl3) δ 163.3, 162.4, 160.6, 155.7, 137.5, 135.8, 130.8, 128.9,
2-carboxamide(5d):Whitesolid;89%yield;m.p.170-172°C; 127.6, 126.9, 126.4, 35.7. HRMS m/z calcd for C15H12N4O2
1H NMR (600 MHz, DMSO-d6) δ 9.30 (t, J = 5.9 Hz, 1H), 8.98 (M-H)- 279.0887; Found 279.0887.
(d, J = 4.9 Hz, 2H), 8.01 (s, 1H), 7.85 (d, J = 8.2 Hz, 2H), 7.70
N-((2-(4-(trifluoromethyl)phenyl)oxazol-4-yl)
(t, J = 4.9 Hz, 1H), 7.34 (d, J = 8.0 Hz, 2H), 4.47 (dd, J = methyl)pyrimidine-5-carboxamide (5j): White solid;
6.0, 0.9 Hz, 2H), 2.37 (s, 3H). 13C NMR (150 MHz, DMSO-d6) 81% yield; m.p. 170 - 172 °C H NMR (500 MHz, CDCl3) δ
1
δ 162.9, 161.2, 158.4, 158.2, 141.0, 139.7, 136.6, 130.2, 126.3, 9.32 (s, 1H), 9.16 (s, 2H), 8.11 (d, J = 8.2 Hz, 3H), 7.77 (s, 1H),
124.7, 123.5, 35.9, 21.5. HRMS m/z calcd for C16H14N4O2 (M-H)- 7.71 (d, J = 8.3 Hz, 3H), 7.19 (brs, 1H), 4.64 (d, J = 5.4 Hz, 2H).
293.1044; Found 293.1040.
13C NMR (125 MHz, CDCl3) δ 163.4, 160.9, 160.7, 155.7, 138.1,
N-((2-phenyloxazol-4-yl)methyl)pyrimidine- 136.6, 132.37 (d, J = 32.8 Hz), 130.1, 127.5, 126.7, 126.0, 125.9
4-carboxamide (5e): White solid; 90% yield; ; 1H NMR (q, J = 3.7 Hz), 123.71 (d, J = 272.3 Hz), 35.8. HRMS m/z calcd
(500 MHz, CDCl3) δ 9.25 (d, J = 1.2 Hz, 1H), 8.98 (d, J = 5.0 for C16H11F3N4O2 (M-H)- 347.0761; Found 347.0759.
Hz, 1H), 8.49 (brs, 1H), 8.14 (dd, J = 5.0, 1.3 Hz, 1H), 8.09 –
N-((2-(4-methoxyphenyl)oxazol-4-yl)methyl)
7.99 (m, 2H), 7.70 (s, 1H), 7.53 – 7.36 (m, 4H), 4.65 (d, J = 5.8 pyrimidine-5-carboxamide (5k): White solid; 83%yield;
Hz, 2H).13C NMR (125 MHz, CDCl3) δ 162.7, 162.2, 159.2, 157.9, m.p. 166 – 167 °C 1H NMR (500 MHz, CDCl3) δ 9.27 (s, 1H),
156.0, 138.0, 135.6, 130.6, 128.8, 127.2, 126.4, 118.6, 35.6. 9.15 (s, 2H), 7.89 (d, J = 8.9 Hz, 2H), 7.63 (s, 1H), 7.51 (s, 1H),
HRMS m/z calcd for C15H12N4O2 (M-H)- 279.0887; Found 6.93 (d, J = 8.9 Hz, 2H), 4.57 (d, J = 5.3 Hz, 2H), 3.83 (s, 3H).
279.0886.
13C NMR (125 MHz, CDCl3) δ 163.8, 162.7, 162.0, 160.9, 156.2,
N-((2-(4-(trifluoromethyl)phenyl)oxazol-4-yl) 137.7, 135.6, 128.4, 128.0, 120.1, 114.7, 55.8, 39.0, 36.2. HRMS
methyl)pyrimidine-4-carboxamide (5f): White solid; m/z calcd for C16H14N4O3 (M-H)- 309.0993; Found 309.0991.
90% yield; m.p. 122 - 124 °C H NMR (500 MHz, CDCl3) δ
1
N-((2-(p-tolyl)oxazol-4-yl)methyl)pyrimidine-
9.26 (d, J = 1.0 Hz, 1H), 8.99 (d, J = 5.0 Hz, 1H), 8.53 (s, 1H), 5-carboxamide(5l):Whitesolid;89%yield;m.p.158-159°C
8.16 – 8.13 (m, 3H), 7.76 (s, 1H), 7.72 (d, J = 8.3 Hz, 2H), 4.67 1H NMR (600 MHz, DMSO-d6) δ 9.38 (t, J = 5.5 Hz, 0H), 9.32
(d, J = 5.9 Hz, 2H). 13C NMR (125 MHz, CDCl3) δ 162.8, 160.7, (s, 0H), 9.20 (s, 1H), 8.11 (s, 1H, 7.85 (d, J = 8.2 Hz, 1H), 7.33
159.3, 157.9, 155.9, 138.6, 136.4, 132.14 (q, J = 32.7 Hz), 130.3, (d, J = 8.0 Hz, 1H), 4.54 – 4.37 (m, 2H), 2.36 (s, 3H). 13C NMR
126.7, 125.83 (q, J = 3.8 Hz), 123.76 (d, J = 272.4 Hz), 118.6, (150 MHz, DMSO-d6) δ 163.6, 161.3, 160.5, 156.4, 141.0, 139.5,

D. Huang et al.: Design, Synthesis and Biological Evaluation of N-((2-phenyloxazol-4-yl)methyl) Pyrimidineꢁ
ꢁ191
containing thiazole and oxazole moieties. J Agric Food Chem. 2019
Sep;67(36):10018–31.
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136.9, 130.2, 128.1, 126.3, 124.7, 36.0, 21.5. HRMS m/z calcd
for C16H14N4O2 (M-H)- 293.1044; Found 293.1042.
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The antifungal activities of the above compounds against
S. sclerotiorum, B. cinerea, and C. fragariae were tested
by the method described in the literature [24]. Briefly, 0.5
mL mycelial plugs of the pathogens were prepared and
transferred into PDA plates supplemented with indicated
concentration of the compounds, respectively. The same
volumes of DMSO were used as a control and all the plates
were incubated at room temperature and the growth rate
was evaluated by the colony diameters in triplicate. The
experiment was repeated thrice. The inhibition rate of the
test compounds against three fungi was calculated by the
below formula, where C represents the diameter of fungi
growth on untreated PDA, T represents the diameter of
fungi on treated PDA, and I is the inhibition rate.
I (%) = [(C - T) ∕ (C-0.4)] × 100%.
Research funding: This work was financially supported
by the National Key Research and Development Program
of China “Research and Development of Comprehensive
Technologies on Chemical Fertilizer and Pesticide Reduc-
tion and Synergism” (2017YFD0201402).
Conflict of interest: Authors state no conflict of interest.
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