Synthesis and fungicidal activity of pyrazolecarboxamide containing α-aminoacetanilide moiety

Article abstract of DOI:10.1155/2012/863135

A series of pyrazolecarboxamides containing α-aminoacetanilide moiety (4) were synthesized. These compounds were characterized by IR, MS and 1H NMR. Their fugicidal activities against Rhizoctonia solani, Sclerotinia sclerotiorum, Monilinia fructicola and

Full text of DOI:10.1155/2012/863135

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
2012, 9(1), 211-218
http://www.e-journals.net
Synthesis and Fungicidal
Activity of Pyrazolecarboxamide
Containing -Aminoacetanilide Moiety
α
ZHI-YONG FANG, HONG JIANG* and XIAO-DONG YE
Department of Chemistry
Huazhong Agricultural University, Wuhan 430070, China
Jianghong0066@126.com
Received 30 June 2011; Accepted 27 August 2011
Abstract: A series of pyrazolecarboxamides containing
α-aminoacetanilide
moiety (4) were synthesized. These compounds were characterized by IR,
MS and 1H NMR. Their fugicidal activities against Rhizoctonia solani,
Sclerotinia sclerotiorum, Monilinia fructicola and Alternaria brassicae
were evaluated. The results show that compound 4l and 4p, which bear
only one electron-donating group on the para-position of phenyl or benzyl
group, possessed excellent inhibitory activities against the above four
fungi.
Keywords: Pyrazole, Glycine, Amide, Fugicidal
Introduction
Pyrazole derivatives have attracted considerable attention in chemical and medicinal
research because of their diverse bioactivities. Particularly, they are widely used as
herbicide, fungicide, insecticide, acaricide and antitumor agents1-10. Motivated by the
aforementioned findings, we conceived that introduction of the α-aminoacetanilide moiety
to pyrazole might result in novel compounds with good biological activities (Scheme 1). The
present study reports the synthesis of a new series of pyrazole-carboxamides obtained by
condensation of N-(4-chloro-3-ethyl-1-methyl-5-pyrazole carboxyl) glycine with substituted
anilines or benzylamine, and the tests of their antifungal activities against hazardous fungi
i.e. Rhizoctonia solani, Sclerotinia sclerotiorum, Monilinia fructicola and Alternaria
brassicae, which cause great loss to crops like rice, Brassica napus L., peach, broccoli etc,
were also carried out.

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Z.Y. FANG HONG JIANG et al.
Et
Cl
Et
Cl
Et
Cl
SOCl2
N
N
N
N
N
CONHCH2COOC2H5
N
COOH
COCl
CH3
2
CH3
CH3
1
Et
Cl
Et
Cl
RNH2
DCC/DMAP
N
N
N
N
CONHCH2CONHR
CONHCH2COOH
CH3
CH3
3
4a 4p
4a 2-ClC6H4, 4b 2,6-F2C6H3, 4c 3-ClC6H4, 4d 2,4-Cl2C6H3, 4e 2,4-F2C6H3, 4f 2-CH3OOCC6H4, 4g
C6H5, 4h 2-CH3C6H4, 4i 4-CH3C6H4, 4j 3-NO2C6H4, 4k 4-NO2C6H4, 4l 4-t-butyl benzyl, 4m 2-FC6H4,
4n 3-FC6H4, 4o 3-CF3C6H4, 4p 4-CH3OC6H4
Scheme 1. Synthesis route for target compounds
Experimental
All the chemicals used were purchased from Shanghai Reagent Co. Melting points of all the
1
compounds determined in WRS-1B digital melting apparatus were uncorrected. The H
NMR spectra were obtained with a DPX 600 MHz (or 400 MHz, 300 MHz) spectrometer
with TMS as internal standard, CDCl3 or DMSO-d6 was used as solvent. The IR spectra
were recorded on an Avatar 330 instrument as potassium bromide pellets. The MS spectra
were performed by using an Agilent 1100 LC/ MSD Trap. Yields refer to isolated products.
Preparation of 4-chloro-3-ethyl-1-methyl-5-pyrazole carboxyl chloride (1)
4-Chloro-3-ethyl-1-methyl-5-pyrazole carboxylic acid was prepared according to
literature11. The pyrazole carboxylic acid (8.6 g, 0.0456 mol) and 2 drops of DMF was
dissolved in toluene (60 mL), stirred at room temperature, thionyl chloride (8.0 mL, 0.1013 mol)
o
was added dropwise in 1 h and the resultant reaction mixture was stirred for 6 h at 60 C.
After removal of the solvent and excess of thionyl chloride under reduced pressure, a
viscous liquid residual was collected as the chloride compound (1) (8.85 g, 93.8%).
Preparation of N-(4-chloro-3-ethyl-1-methyl-5-pyrazole carboxyl) glycine (3)
100 mL two necked round bottom flask fitted with a reflux condenser, a dropping funnel
was used, 0.68 g (0.0048 mol) ethyl glycinate hydrogen chloride and 10 mL
dichloromethane was injected into it in ice cold water bath (-1 ∼0 oC) and 2.5 mL
triethylamine added drop wise with stirring. Then 1.0 g (0.0048 mol) 4-chloro-3-ethyl-1-
methyl-5-pyrazole carboxyl chloride (1) in 10 mL dichloromethane was added through a
funnel in 0.5 h. The mixture was stirred around 0 oC until the reaction was completed (TLC
monitor, usually about 3 h). After filtration of the insoluble material from the mixture, the
filtrate was washed with 15 mL 5% HCl, 15 mL 10% NaHCO3, 15 mL water and finally 15 mL
20% brine. The solution was dried over magnesium sulphate and the solvent was evaporated
under reduced pressure. Ethyl N-(4-chloro-3-ethyl-1-methyl-5-pyrazole carboxyl) glycinate
(2) was obtained as white solid. Then 15 mL diethyl ether, 0.4 g NaOH and 5 drops of water
were injected into the flask to make the ester hydrolyzed. After the completion of hydrolysis
by TLC monitor, the corresponding sodium salt was collected by filtration. Finally the
sodium salt was redissolved in 10 mL water and acidified to pH=2∼3 by concentrated HCl.
The precipitate was collected by filtration and dried at 80 oC. A white solid was collected as the
N-(4-chloro-3-ethyl-1-methyl-5-pyrazole carboxyl) glycine (3) (0.53 g, 45.2%), m.p.175∼176
oC. IR(KBr) ν: 3321, 1736, 1643, 1554, 1513 and 1469 cm-1.

Synthesis and Fungicidal Activity of Pyrazolecarboxamide
213
General procedure for the synthesis of 4a-p
The synthesis method was exemplified by the preparation of compound 4a. Compound 3
(1.0 g, 0.004 mol), o-chloroaniline (0.51 g, 0.004 mol), N, N'-dicyclo -hexyl carbodiimide
(DCC, 0.99 g, 0.0048 mol) and 15 mL CH2Cl2 was added successively into 100 mL three
o
necked round bottom flask. After stirring for 15 min in cold water bath ( ∼5 C), 4-dimethyl-
aminepyridine (DMAP, 0.05 g, 0.0004 mol) was added. Then the mixture was warmed to
room temperature and stirred for 4 h. After filtration of insoluble material from the mixture,
the solution was washed with 15 mL 5% NaOH, 15 mL 5% HCl, 15 mL 20% brine. The
solution was dried over magnesium sulphate and the solvent was evaporated under reduced
pressure. Compound 4a was obtained as white solid. After recrystallization in ethanol, pure
white 4a (1.10 g, 77.6%) was provided. Others compounds were synthesized by the way
similar to compound 4a.
N-[2-[(2-Chlorophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4a)
o
Yield 77.6%, white solid, m.p.120.9∼121.3 C; 1H NMR(CDCl3, 400 MHz) δ: 1.166∼1.204
(t, J = 7.6 Hz, 3H, C-CH3), 2.560∼2.617 (q, J = 7.6 Hz, 2H, -CH2CH3), 4.081(s, 3H, N-
CH3), 4.261∼4.275 (d, J = 5.6 Hz, 2H, -CH2-N), 7.004∼7.021 (d, J = 6.8 Hz, 1H, -Ph),
7.193∼7.235 (t, J = 8.4 Hz, 1H, -Ph), 7.297∼7.319 (d, J = 8.8 Hz, 1H, -Ph), 7.447(s, 1H, -
Ph), 8.225 (br s, 1H, -NHPh), 8.264∼8.285 (br s, 1H, -NHCH2); IR (KBr) ν: 3341, 3316,
1708, 1638, 1594, 1527, 1505, 1470, 758 cm-1; MS m/z (%): 355 (M+., 100), 228 (8.6).
N-[2-[(2,6-Difluorophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-
pyrazole -5-carboxamide (4b)
o
Yield 49.4%, white solid, m.p.161.7∼162.3 C; 1H NMR(CDCl3, 600 MHz) δ: 1.231∼1.256
(t, J = 7.2 Hz, 3H, C-CH3), 2.628∼2.665 (q, J = 7.2 Hz, 2H, -CH2CH3), 4.116(s, 3H, N-CH3),
4.385∼4.404 (d, J = 11.4 Hz, 2H, -CH2-N), 6.957∼6.984 (t, J = 7.8 Hz, 2H,-Ph),
7.236∼7.240 (m, 1H, -Ph), 7.607∼7.608 (d, J = 0.6 Hz, 1H, -NHCH2), 7.850 (s, 1H, -NHPh);
IR (KBr) ν: 3417, 3255, 1682, 1669, 1625, 1603, 1536, 1505 cm-1; MS m/z (%): 357 (M+.,
100), 228 (4.8).
N-[2-[(3-Chlorophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4c)
Yield 50.1% white solid, m.p.146.5∼147.3 oC; 1H NMR(CDCl3, 400 MHz) δ: 1.157∼1.194
(t, J = 7.4 Hz, 3H, C-CH3), 2.547∼2.604 (q, J = 7.4 Hz, 2H, -CH2CH3), 4.037(s, 3H, N-
CH3), 4.258∼4.271 (d, J = 5.2 Hz, 2H, -CH2-N), 7.004∼7.026 (d, J = 8.8 Hz, 1H, -Ph),
7.130∼7.193 (m, 1H, -Ph), 7.283∼7.303 (d, J = 8 Hz, 1H, -Ph), 7.568 (s, 1H, -Ph), 7.631 (br
s, 1H, -NH), 8.608 (br s, 1H, -NH); IR (KBr) ν: 3366, 3328, 1704, 1644, 1596, 1530, 1501,
1479 cm-1; MS m/z (%): 355 (M+., 100).
N-[2-[(2,4-Dichlorophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-
pyrazole-5-carboxamide (4d)
o
1
Yield 63.3%, white solid, m.p.159.3∼160.4 C; H NMR(CDCl3, 500 MHz) δ: 1.169∼1.199
(t, J = 7.5 Hz, 3H, C-CH3), 2.563∼2.609 (q, J = 7.5 Hz, 2H, -CH2CH3), 4.079(s, 3H, N-CH3),
4.247∼4.258 (d, J = 5.5 Hz, 2H, -CH2-N), 7.178∼7.185 (d, J =3.5 Hz, 1H, -Ph), 7.193∼7.200 (d,
J = 3.5 Hz, 1H, -Ph), 7.323 (s, 1H, -Ph), 8.248(br s, 1H, -NH), 8.266 (br s, 1H, -NH); IR (KBr) ν:
3407, 3319, 1672, 1650, 1584, 1527, 1505, 1470 cm-1; MS m/z (%): 389 (M+., 100).

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Z.Y. FANG HONG JIANG et al.
N-[2-[(2,4-Difluorophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-
pyrazole-5-carboxamide (4e)
o
Yield 48.6%, white solid, m.p.147.9∼148.0 C; 1H NMR(CDCl3, 500 MHz) δ: 1.166∼1.196
(t, J = 7.5 Hz, 3H, C-CH3), 2.561∼2.606 (q, J = 7.5 Hz, 2H, -CH2CH3), 4.067(s, 3H, N-
CH3), 4.247∼4.258 (d, J =5.5 Hz, 2H, -CH2-N), 6.804∼6.825 (m, 2H,-Ph), 7.448 (s, 1H, -
Ph), 8.105∼8.140 (m, 2H, -NH); IR (KBr) ν: 3344, 3278, 1706, 1637, 1562, 1530, 1505 cm-1;
MS m/z (%): 357 (M+., 100).
N-[2-[(2-Methoxylcarbonylphenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-
1H-pyrazole-5-carboxamide (4f)
Yield 49.6%, white solid, m.p.139.2∼140.1 oC; 1H NMR(CDCl3, 600 MHz) δ: 1.246∼1.271 (t, J
= 7.5 Hz, 3H C-CH3), 2.646∼2.684 (q, J= 7.5 Hz, 2H, -CH2CH3), 3.877(s, 3H,-OCH3), 4.151(s,
3H, N-CH3), 4.354∼4.362 (d, J = 4.8 Hz, 2H, -CH2-N), 7.106∼7.133 (m, 1H, -Ph), 7.513∼7.574
(m, 2H, -Ph), 8.022∼8.038 (m, 1H, -Ph), 8.694 (br s, 1H, -NH), 11.464 (br s, 1H, -NH);IR (KBr)
ν: 3290, 3265, 1691, 1660, 1590, 1524 cm-1; MS m/z (%): 379 (M+., 100),152(7.5).
N-[2-[Phenylamino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-5-
carboxamide (4g)
Yield 80.3%, white solid, m.p.136∼137 oC; 1H NMR(CDCl3, 400 MHz) δ: 1.232∼1.270 (t, J = 7.6
Hz, 3H, C-CH3), 2.623∼2.680 (q, J = 7.6 Hz, 2H, -CH2CH3), 4.115(s, 3H, N-CH3), 4.316∼4.327 (d,
J = 4.4 Hz, 2H, -CH2-N), 7.114∼7.150 (t, 1H), 7.306∼7.344 (t, 2H, -Ph), 7.509∼7.529 (d, J = 4.0
Hz, 2H, -Ph), 7.649∼7.658 (br s, -NH), 8.258 (br s, 1H, -NH) ; IR (KBr) ν: 3350, 3325, 1701, 1637,
1609, 1552, 1527, 1501 cm-1; MS m/z (%): 321 (M+., 100), 228(16.3).
N-[2-[(2-Methylphenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4h)
Yield 61.8%, white solid, m.p.105∼107 oC;1H NMR(CDCl3, 400 MHz) δ: 1.228∼1.266 (t, J = 7.6
Hz, 3H, C-CH3), 2.261 (s, 3H, -CH3Ph), 2.619∼2.676 (q, J = 7.6 Hz, 2H, -CH2CH3), 4.128(s, 3H,
N-CH3), 4.304∼4.318 (d, J = 5.6 Hz, 2H, -CH2-N), 7.072∼7.109 (t, 1H, -Ph), 7.179∼7.228 (q, 2H, -
Ph), 7.604-7.619 (d, J = 6 Hz, 1H, -Ph), 7.824 (br s, 1H, -NH), 7.943 (s, 1H, -NH); IR (KBr) ν:
3417, 3259, 1663, 1590, 1536, 1508 cm-1; MS (70eV) m/z (%): 335 (M+., 100), 228(6.7).
N-[2-[(4-Methylphenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4i)
Yield 62.4%, white solid, m.p.184∼185 oC; 1H NMR(CDCl3, 400 MHz) δ: 1.231∼1.269 (t, J = 7.6
Hz, 3H, C-CH3), 2.317 (s, 3H, -CH3Ph), 2.624∼2.681 (q, J = 7.6 Hz, 2H, -CH2CH3), 4.127 (s, 3H,
N-CH3), 4.280∼4.293 (d, J = 5.2 Hz, 2H, -CH2-N), 7.121∼7.142 (d, J = 8.4 Hz, 2H, -Ph),
7.384∼7.405 (d, J = 8.4 Hz, 2H, -Ph), 7.599 (br s, 1H, -NH), 7.982 (br s, 1H, -NH) ; IR (KBr) ν:
3335, 3278, 1701, 1637, 1612, 1530, 1505, 814 cm-1; MS m/z (%): 335 (M+., 100), 228(6.5).
N-[2-[(3-Nitrophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4j)
Yield 33.0%, pale yellow solid, m.p.186∼188 oC;1H NMR(CDCl3, 400 MHz) δ: 1.237∼1.275 (t, J =
7.6 Hz, 3H, C-CH3), 2.632∼2.689 (q, J = 7.6 Hz, 2H, -CH2CH3), 4.157 (s, 3H, N-CH3), 4.323∼4.337
(d, J = 5.6 Hz, 2H, -CH2-N), 7.485∼7.526 (t, 1H, -Ph ), 7.583 (s, 1H, -Ph), 7.919∼7.939 (d, J = 8 Hz,
1H, -Ph), 7.975∼7.996 (q, 1H, -Ph), 8.420 (s, 1H, -NH), 8.655 (s, 1H, -NH); IR (KBr) ν:
3354, 3300, 1701, 1650, 1600, 1546, 1530, 1505 cm-1; MS m/z (%): 366 (M+., 100).

Synthesis and Fungicidal Activity of Pyrazolecarboxamide
215
N-[2-[(4-Nitrophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4k)
Yield 32.3%, pale yellow solid, m.p.214∼215 oC; 1H NMR(CDCl3, 600 MHz) δ: 1.167∼1.193 (t,
J = 7.8 Hz, 3H, C-CH3), 2.565∼2.603 (q, J = 7.6 Hz, 2H, -CH2CH3), 4.073(s, 3H, N-CH3),
4.246∼4.255 (d, J = 5.4 Hz, 2H, -CH2-N), 7.513 (s, 1H, -NH), 7.649∼7.664 (d, J = 9 Hz, 2H, -
Ph), 8.133∼8.148 (d, J = 9 Hz, 2H, -Ph), 8.851 (s, 1H, -NH);IR (KBr) ν: 3379, 3347, 1713, 1656,
1615, 1562, 1530, 1505, 855 cm-1; MS m/z (%): 366 (M+., 100), 225(50).
N-[2-[(4-tert-butylbenzylyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-
pyrazole-5-carboxamide (4l)
o
1
Yield 96.0%, white solid, m.p.122∼123 C; H NMR(CDCl3, 600 MHz) δ: 1.232∼1.257
(t, J = 7.5 Hz, 3H, C-CH3), 1.304 (s, 9H, -C(CH3)3), 2.629∼2.667 (q, J = 7.6 Hz, 2H, -
CH2CH3), 4.078(s, 3H, N-CH3), 4.142∼4.150 (d, J = 4.8 Hz, 2H, -CH2-N), 4.461∼4.470 (d, J
= 5.4 Hz, 2H -CH2Ph), 6.318(s, 1H, -NH), 7.211∼7.225 (d, J = 8.4 Hz, 2H, -Ph),
7.351∼7.365 (d, J = 8.4 Hz, 2H-Ph), 7.531 (s, 1H,-NH); IR (KBr) ν: 3388, 3354, 2964, 1679,
1647, 1524, 1495 cm-1; MS m/z (%): 391 (M+., 100).
N-[2-[(2-fluorophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4m)
o
Yield 44.4%, white solid, m.p.163∼164 C; 1H NMR(CDCl3, 600 MHz) δ: 1.165∼1.191
(t, J = 7.8 Hz, 3H, C-CH3), 2.562∼2.600 (q, J = 7.6 Hz, 2H, -CH2CH3), 4.069(s, 3H, N-
CH3), 4.252∼4.261 (d, J = 5.4 Hz, 2H, -CH2-N), 7.013∼7.076 (m, 3H, -Ph), 7.536∼7.545
(d, J = 5.4 Hz, 1H, -Ph), 8.256 (s, 1H, -NH), 8.283 (s, 1H, -NH);IR (KBr) ν: 3341, 3290,
1707, 1637, 1619, 1596, 1533, 1508 cm-1; MS m/z (%): 339 (M+., 100), 225 (28.6).
N-[2-[(3-fluorophenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4n)
42.9%, white solid, m.p.151∼152 oC; 1H NMR(CDCl3, 600 MHz) δ: 1.165∼1.191 (t, J = 7.8
Hz, 3H, C-CH3), 2.562∼2.600 (q, J =7.6 Hz, 2H, -CH2CH3), 4.061(s, 3H, N-CH3),
4.214∼4.222 (d, J = 4.8 Hz, 2H, -CH2-N), 6.744∼6.769 (t, 1H,-Ph), 7.169∼7.183 (d, J = 8.4
Hz, 1H, -Ph), 7.269∼7.275 (d, J = 3.6 Hz, 1H, -Ph),7.492∼7.509 (d, J = 10.2 Hz, 1H, -Ph),
7.593 (s, 1H, -NH), 8.421 (s, 1H, -NH);IR (KBr) ν: 3328, 2936, 1701, 1637, 1609, 1536,
1508, 1489 cm-1; MS m/z (%): 339 (M+., 100), 225 (51).
N-[2-[(3-trifluoromethylphenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-
pyrazole-5-carboxamide (4o)
o
1
Yield 38.0%, brown solid, m.p.154∼155 C; H NMR(CDCl3, 600 MHz) δ: 1.244∼1.269
(t, J = 7.5 Hz, 3H, C-CH3), 2.647∼2.685 (q, J = 7.6 Hz, 2H, -CH2CH3), 4.140(s, 3H,
N-CH3), 4.280∼4.288 (d, J = 4.8 Hz, 2H, -CH2-N), 6.846∼6.861 (d, 2H, -Ph), 7.406∼7.421
(m, 2H, -Ph), 7.637 (br s, 1H, -NH), 8.068 (br s, 1H, -NH);IR (KBr) ν: 3357, 3281, 1694,
1641, 1609, 1555, 1527, 1505 cm-1; MS m/z (%): 389 (M+., 100).
N-[2-[(4-methoxylphenyl)amino]-2-oxoethyl]-1-methyl-3-ethyl-4-chloro-1H-pyrazole-
5-carboxamide (4p)
o
1
Yield 75.2%, white solid, m.p.130∼131 C; H NMR(CDCl3, 600 MHz) δ: 1.172∼1.197
(t, J = 7.5 Hz, 3H, C-CH3), 2.176 (s, 3H, O-CH3), 2.571∼2.609 (q, J = 7.6 Hz, 2H, -CH2CH3),

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Z.Y. FANG HONG JIANG et al.
4.078 (s, 3H, N-CH3), 4.233∼4.242 (d, J = 5.4 Hz, 2H, -CH2-N), 7.314∼7.327 (d, J = 7.8 Hz,
1H, -Ph), 7.371∼7.379 (t, J = 4.8 Hz, 1H, -Ph), 7.501∼7.509 (d, J = 4.8 Hz, 1H, -Ph),
7.653∼7.666 (d, J = 7.8 Hz, 1H, -Ph), 7.770 (s, 1H, -NH), 8.310 (s, 1H, -NH); IR (KBr) ν:
3376, 3331, 1701, 1641, 1600, 1562, 1536, 1505 cm-1; MS m/z (%): 379 (M+., 100),152(15.5).
Antifungal activities
Radial fungal-growth assay
The antifungal activity was tested in vitro on Rhizoctonia solani, Sclerotinia sclerotiorum,
Monilinia fructicola and Alternaria brassicae. The activities of the compounds were assayed
as growth inhibition. Each compound was dissolved in acetone plus Tween 80 (1.0%). Equal
volumes of acetone containing tested compounds were added to sterile cool agar media (Potato
Dextrose Agar Difco) to give final 50 mg/L concentration for each substance. The final
acetone concentration did not exceed 1.0% of the final volume in both control and treated
cultures. Compound-amended agar medium was dispersed aseptically onto 9 cm diameter
plastic Petri dishes (10 mL/dish). Each dish was inoculated with a 0.5 cm diameter mycelial
disc of actively growing colonies. Three replicates were used for each compound, together
with controls containing toxicant-free medium. The growth inhibition was calculated from
mean differences between treated and control cultures as a percentage of the latter. The results
were compared with standard fungicide Carbendazim. The growth was determined after 2 days
of incubation for Rhizoctonia solani and Sclerotinia sclerotiorum, 4 days for Monilinia
fructicola and Alternaria brassicae.
Results and Discussion
Synthesis
For the synthesis of compound 2, which was prepared by the amination of acyl chloride (1),
0
the temperature should be controlled around 0 C. When the temperature was higher, the
side reaction of amination between glycinate would take place, leading to polymerization12,
that is, the amino group of one molecule ethyl glycinate could attack the ester group of
another molecule of ethyl glycinate.
Two different strategies were applied to obtain the series of title compounds (4a-4p);
the first one involved the acyl chloride of compound 3 with different anilines, however,
there was side reaction between the acyl chloride group of compound 3 and the amine group
on itself, moreover, the side product was hard to be removed; the second one, which was
applied by this paper, exploited the DCC/DMAP system. DCC can transform the acid into
corresponding anhydride and DMAP can efficiently promote acylation of aniline with acid
anhydrides to give the corresponding amides in good yields13.
1
The H-NMR signals of the two NH units in title compounds were variable, which on
the one hand, correlate with the chemical structure of the phenyl group connected to NH, on
the other hand were strongly influenced by hydrogen bonding. It is well known that the more
hydrogen bonding there is, the more the proton is deshielded and the higher its chemical
shift will be. However, since the amount of hydrogen bonding is susceptible to factors such
as solvation, concentration and temperature, so the chemical shift of NH units were not the
same for all title compounds.
Fungicidal activities
The results of the in vitro fungistatic activity of compounds 4a 4p and commercial fungicide
Carbendazim at 50 mg/L against fungi Rhizoctonia solani, Sclerotinia sclerotiorum, Monilinia

Synthesis and Fungicidal Activity of Pyrazolecarboxamide
217
fructicola and Alternaria brassicae are listed in Table 1, in which the fungistatic activity was
expressed as inhibition percentage. The results in Table 2 showed that the synthesized target
compounds were fairly active against nearly all four fungi to some extent. Compared to the
control Carbendazim (58.7%), some of the compounds showed significant activities against
Sclerotinia sclerotiorum, for example, the inhibition rates compounds 4c, 4f, 4l and 4p were all
above 50% at 50 mg/L. Particularly, for compound 4l, the inhibition rate on Sclerotinia
sclerotiorum was above 80%. Furthermore, compounds 4l and 4p, exhibited very strong
inhibition against the other three fungi. The common structural feature of both was that the
benzene ring or benzyl group (4l) was substituted with only one strong electron-donating
substitute at site-4. Furthermore, when R was benzyl group (viz 4l) instead of a phenyl group,
there was a dramatic increase in the activity, which suggests that the substitute on the amino
moiety likely plays a positive role in the mechanism of their antifungal action.
Table 1. Antifungal activity of title compounds
Inhibitiory percentage, %
Compound
Rhizoctonia
solani
Sclerotinia
sclerotiorum
21.0
Monilinia
fructicola
26.5
Alternaria
brassicae
17.8
0
4a
0
36.1
50.6
8.4
30.6
31.6
22.7
39.4
50.2
32.8
28.4
43.8
32.2
18.9
64.4
34.4
13.9
32.7
69.4
100
13.9
48.9
38.9
32.2
65.0
15.0
27.8
36.1
36.1
9.4
4b
57.8
20.3
24.3
25.6
0
4c
4d
16.0
53.5
22.7
27.9
23.8
23.6
17.1
83.8
29.0
22.6
18.2
54.1
58.7
4e
4f
4g
0
4h
41.9
0
4i
4j
0
4k
62.5
19.9
0
80.6
17.8
12.2
52.2
86.6
92.8
4l
4m
4n
57.4
61.8
100
4o
4p
Carbendazim
Conclusion
On the whole, most of the title compounds exhibited good fungicidal activity. Hence, title
compound could be useful for further optimization work in finding the potential antifungal
compounds.
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