Synthesis and herbicidal activity of novel 4-acyl-2,5-disubstituted-3- hydroxypyrazoles and 4-arylcarbonyl-3-substitutedisoxazol-5-ones

Article abstract of DOI:10.1002/jhet.1659

Two series of novel 4-acyl-2,5-disubstituted-3-hydroxypyrazoles 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h and 4-arylcarbonyl-3-substitutedisoxazol-5-ones 7a, 7b, 7c, 7d, 7e, 7f, 7g, 7h, 7i were synthesized by the Scotton-Baumann reaction of 2,5-disubstituted-2,4-dihydro-pyrazol-3-ones 1 or 3-substituted-4H-isoxazol-5- ones 6 and various acyl chlorides, followed by the Fries rearrangement in the presence of calcium hydroxide and calcium oxide as the catalyst. Their structures were confirmed by IR, ¹H NMR, mass spectroscopy, and elemental analyses. ¹H NMR indicated that compounds 3 existed in enol forms and compounds 7 in keto configurations. The results of preliminary bioassays showed that some of the title compounds 3 and 7 exhibited moderate to good herbicidal activities against Brassica campestris L. at the concentration of 100 mg/L. Isoxazole compounds 7 showed better herbicidal activity against B. campestris L. than pyrazole compounds 3 did at the concentration of 100 mg/L. Moreover, most of the isoxazole compounds displayed higher herbicidal activity against B. campestris L. than Echinochloa crus-galli. However, these compounds showed weak herbicidal activities at the concentration of 10 mg/L.

Full text of DOI:10.1002/jhet.1659

Month 2013
Synthesis and Herbicidal Activity of Novel 4-Acyl-2,5-disubstituted-3-
hydroxypyrazoles and 4-Arylcarbonyl-3-substitutedisoxazol-5-ones
a
a
a
Hong Song,a,b Wei-Bing Feng, Feng Cheng and De-Qing Shi
*
aKey Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal
University, Wuhan 430079, Hubei, China
bWuhan Bioengineering Institute, Yangluo 430415, Hubei, China
*
E-mail: chshidq@mail.ccnu.edu.cn
Received December 4, 2011
DOI 10.1002/jhet.1659
Published online 00 Month 2013 in Wiley Online Library (wileyonlinelibrary.com).
H C
H C
Cl
O
O
N
N
R
N
CH
N
CH
Cl
N
R
R
O
N
N
Caa(OH) /CaO
1,4-dioxane
Cl
S
N
N
or
N
O
or
N
N
S
N
R
Cl
N
N
+
OH
OH
N
N
N
O
R
R
2b
2a
1
3a-3d
3e-3h
O
R
R
O
O
Et N
Ca(OH) /CaO
Ar
+
HCl.NH OH
N
R
OC H
O
N
ArCOCl
O
O
O
5
6
7a-7i
Two series of novel 4-acyl-2,5-disubstituted-3-hydroxypyrazoles 3a–3h and 4-arylcarbonyl-3-substitutedi-
soxazol-5-ones 7a–7i were synthesized by the Scotton–Baumann reaction of 2,5-disubstituted-2,4-
dihydro-pyrazol-3-ones 1 or 3-substituted-4H-isoxazol-5-ones 6 and various acyl chlorides, followed by the
Fries rearrangement in the presence of calcium hydroxide and calcium oxide as the catalyst. Their structures
were confirmed by IR, 1H NMR, mass spectroscopy, and elemental analyses. 1H NMR indicated that
compounds 3 existed in enol forms and compounds 7 in keto configurations. The results of preliminary bioas-
says showed that some of the title compounds 3 and 7 exhibited moderate to good herbicidal activities against
Brassica campestris L. at the concentration of 100 mg/L. Isoxazole compounds 7 showed better herbicidal
activity against B. campestris L. than pyrazole compounds 3 did at the concentration of 100 mg/L. Moreover,
most of the isoxazole compounds displayed higher herbicidal activity against B. campestris L. than Echinochloa
crus-galli. However, these compounds showed weak herbicidal activities at the concentration of 10mg/L.
J. Heterocyclic Chem., 00, 00 (2013).
INTRODUCTION
RESULTS AND DISCUSSION
(4-Hydroxyphenyl)pyruvate dioxygenase (EC 1.13.11.27,
HPPD), an a-keto acid-dependent nonheme iron(II) dioxy-
genase, catalyzes the second step in the catabolism of
tyrosine, a reaction involving decarboxylation, substituent
migration, and aromatic oxygenation, the conversion of
(4-hydroxyphenyl)pyruvate (HPP) to homogentisate. By
inhibiting the production of homogentisate, tocopherols
and plastoquinones can no longer be synthesized. Continued
scientific interest in HPPD has arisen from the importance
of this enzyme in the treatment of type 1 tyrosinemia and
alkaptonuria and also as a target for the development of
herbicides [1–5]. Some commercially HPPD inhibitors,
including mesotrione, sulcotrione, and isofluxatole, are used
as selective broad leaf herbicides [6–10]. To find novel
HPPD inhibitor lead compounds with high activity and
low toxicity, on the basis of the commercially HPPD
herbicides, pyrazoxyfen, and isoxaflutole as lead com-
pounds, we designed and synthesized two series of novel
4-acyl-2,5-disubstituted-3-hydroxypyrazoles 3 and 4-aroyl-
3-substitutedisoxazol-5-ones 7. Herein, we would like to
report the synthesis and herbicidal activities of the title
compounds 3 and 7 in this article (Scheme 1).
The target compounds 3 and 7 were synthesized by
the Scotton–Baumann reaction of 2,5-disubstituted-
2,4-dihydro-pyrazol-3-ones 1 or 3-substituted-4H-isoxazol-
5-ones 6 and various acyl chlorides followed by the
Fries rearrangement in the presence of calcium hydroxide
and calcium oxide as the catalyst. On one hand, calcium
hydroxide can remove hydrochloride formed in the
Scotton–Baumann reaction, so it can improve the yields
of the Scotton–Baumann reaction [11,12]. On the other
hand, calcium ion can form the complex with the 4-acyl-
3-hydroxypyrazole and 4-acylisoxazol-5-one and prevent
the multi-acylation reaction.
The structures of compounds 3 and 7 were deduced from
their spectral data (IR, 1H NMR, and EIMS) and elemental
analyses, which were listed in the experimental part. In the
1H NMR spectra of 3a, the two methyl protons attached
pyrazole and thiadiazole rings displayed as two singlets
with chemical shift d 2.0 and 2.8, respectively; in some
1
cases, the OH proton cannot be found in their H NMR
spectra; the aromatic protons exhibited as multiple peaks
with chemical shifts d ca. 7.4–8.4; 1H NMR data indicated
1
that compounds 3 existed in enol forms. In the H NMR
© 2013 HeteroCorporation

H. Song, W.-B. Feng, F. Cheng, and D.-Q. Shi
Vol 000
Scheme 1. Synthetic route to compounds 3 and 7.
H C
H C
Cl
O
O
N
N
R
N
CH
N
CH
Cl
N
R
R
O
N
N
Caa(OH) /CaO
1,4-dioxane
Cl
S
N
N
or
N
O
or
N
N
S
N
R
Cl
N
N
+
OH
OH
N
N
N
O
R
R
2b
2a
1
3a-3d
3e-3h
O
R
R
O
O
Et N
Ca(OH) /CaO
Ar
+
HCl.NH OH
N
R
OC H
O
N
ArCOCl
O
O
O
5
6
7a-7i
spectra of 7a, the methyl protons attached isoxazole
ring displayed as a singlet with chemical shift d 2.7; the
aromatic protons exhibited as multiple peaks with chemical
shifts d ca. 7.2–8.2; the proton linking to the saturated
carbon of isoxazole displayed a singlet with chemical shifts
d 5.4, which indicated that the compounds existed in keto
configurations; IR spectra of compounds 3 and 7 showed
normal stretching absorption bands, indicating the existence
of OH (~3450 cmÀ1), Ar-H (~3050 cmÀ1), C═O (~1750,
~1650 cmÀ1), Ar (1580, 1510, 1480 cmÀ1). The EI mass
spectra of compounds 3c and 7a revealed the existence of
the molecular ion peaks m/z 320 and 203, respectively, and
related fragment ion peaks, which were in good accordance
with the given structures of products.
Herbicidal activity. The preliminary herbicidal activity
(in vitro) of the title compounds 3 and 7 against Brassica
campestris L. (rape) and Echinochloa crus-galli (barnyard
grass) has been investigated at the dosages of 100 and
10mg/L according to the method described in the
experimental section and are listed in Table 1. The results
of preliminary bioassays showed some of the title compounds
3 and 7 that exhibited moderate to good herbicidal activities
against dicotyledonous plants (B. campestris L.) at the
concentration of 100 mg/L. For example, compounds
3f, 3h, 7b, 7c, 7d, 7f, and 7g possessed 77.0%,
86.3%, 84.8%, 96.7%, 92.5%, 81.3%, and 82.5%
inhibition against B. campestris L., respectively, at the
concentration of 100 mg/L. For the preliminary structure–
activity relationships, we noticed that most of the isoxazole
compounds 7 showed better herbicidal activity against
B. campestris L. than pyrazole compounds 3 did at the
concentration of 100 mg/L; for compounds 3, firstly, the
compound when R1 is phenyl showed better activity
against B. campestris L. than those when R1 is methyl;
secondly, these compounds containing 1,2,3-thiadiazole
ring seem to display better activity than those containing
1,2,3-triazole ring did. As for compounds 7, firstly, the
different substituents in benzene ring have some influence
on the herbicidal activity; these compounds with chlorine
in the benzene ring exhibited better herbicidal activity than
those with methyl and fluorine substituted did; secondly,
the compounds when R3 is methyl showed better activity
than those of phenyl did. Compounds 3 and 7 showed
better activity, which can be explained as follows: both of
hydroxyl and carbonyl groups in the compounds 3 and 7
can combine with Fe(II) ion tightly, so they exhibit better
HPPD inhibitory activity.
Moreover, these compounds displayed higher herbicidal
activity against dicotyledonous plant (B. campestris L.)
than monocotyledonous one (E. crus-galli). However,
Table 1
The herbicidal activities of compounds 3 and 7 (in vitro, percent inhibition).
Brassica campestris
Echinochloa crus-galli
Brassica campestris
Echinochloa crus-galli
root test
cup test
root test
cup test
Compound
100 mg/L
10 mg/L
100 mg/L
10 mg/L
Compound
100 mg/L
10 mg/L
100 mg/L
10 mg/L
3a
3b
3c
3d
3e
3f
68.6
65.1
63.5
53.6
49.2
77.0
40.0
86.3
40.9
20.0
15.8
14.0
11.3
38.6
25.3
45.6
40.0
40.0
25.0
40.0
25.0
15.0
20.0
35.0
25.0
15.0
10.0
20.0
15.0
10.0
10.0
10.0
7a
7b
7c
7d
7e
7f
7g
7h
7i
71.5
84.8
96.7
92.5
78.6
81.3
82.5
48.0
79.8
40.2
40.6
54.3
67.6
43.7
45.8
42.4
38.2
42.5
35.0
20.0
20.0
45.0
30.0
20.0
35.0
20.0
35.0
10.0
10.0
10.0
15.0
10.0
10.0
10.0
10.0
15.0
3g
3h
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2013
Synthesis and Herbicidal Activity of Novel 4-Acyl-2,
5-disubstituted-3-hydroxypyrazoles and 4-Arylcarbonyl-3-substitutedisoxazol-5-ones
Data for 3b (R1 = CH3, R2 = 4-ClC6H4). Light yellow solid,
yield: 84%, mp 139–141ꢀC; 1H NMR (CDCl3, 600 MHz): d 1.96
(s, 3H, CH3), 2.81 (s, 3H, CH3), 7.46 (d, J = 8.4 Hz, 2H, Ar-H),
7.81 (d, J = 9.0 Hz, 2H, Ar-H); IR (KBr) υ: 3148 (OH), 3045
(ArH), 1670 (C═O), 1618, 1556, 1598 (Ar) cmÀ1; EIMS
(70 eV): m/z 334 (M+, 5), 320 (96), 306 (44), 277 (43.7), 245
(32.7), 235 (23.8), 207 (39), 181 (28.8), 139 (39.8), 111 (100),
81(29.6), 69 (38.8). Anal. Calcd for C14H11ClN4O2S: C, 50.23;
H, 3.31; N, 16.74. Found: C, 50.32; H, 3.25; N, 16.83.
these compounds showed weak herbicidal activities at
the concentration of 10 mg/L. Further biological activity
evaluation and their structure–activity relationship investi-
gation are on the way.
In conclusion, two series of novel 4-acyl-2,5-disubstituted-
3-hydroxypyrazoles 3a–3h and 4-aroyl-3-substitutedisoxazol-
1
5-ones 7a–7i were designed and synthesized. H NMR
indicated that compounds 3 existed in enol forms and com-
pounds 7 in keto configurations. The results of preliminary
bioassays showed some of the title compounds 3 and 7 that
exhibited moderate to good herbicidal activities against
dicotyledonous plants (B. campestris L.) at the concentration
of 100 mg/L. Isoxazole compounds 7 showed better
herbicidal activity against B. campestris L. than pyrazole
compounds 3 did.
Data for 3c (R1 = CH3, R2 = 4-FC6H4). Light yellow solid,
yield: 85%, mp 174–176ꢀC; 1H NMR (CDCl3, 600 MHz): d 1.96
(s, 3H, CH3), 2.81 (s, 3H, CH3), 7.20 (t, J = 8.4 Hz, 2H, Ar-H),
7.20 (dd, J = 4.8 Hz, J = 7.8 Hz, 2H, Ar-H); IR (KBr) υ: 3125
(OH), 3057 (ArH), 1671 (C═O), 1618, 1561, 1509 (Ar) cmÀ1
;
EIMS (70 eV): m/z 318 (M+, 7.8), 290 (65), 262 (22.4), 229
(18.4), 218 (67.4), 178 (34.5), 109 (44.7), 95 (100), 75 (26.7).
Anal. Calcd for C14H11FN4O2S: C, 52.82; H, 3.48; N, 17.60.
Found: C, 52.71; H, 3.58; N, 17.74.
Data for 3d (R1 = C6H5, R2 = C6H5). Light brown solid, yield:
89%, mp 170–172ꢀC; 1 H NMR (CDCl3, 600 MHz): d 2.60 (s, 3H,
CH3), 7.19–7.21 (m, 4H, Ar-H), 7.28–7.32 (m, 1H, Ar-H), 7.39
(t, J = 7.8 Hz, 1H, Ar-H), 7.51 (t, J = 7.2 Hz, 2H, Ar-H), 7.93
(d, J = 7.2 Hz, 2H, Ar-H); IR (KBr) υ: 3214 (OH), 3036 (ArH),
1676 (C═O), 1621, 1555, 1515 (Ar) cmÀ1. Anal. Calcd for
C19H14N4O2S: C, 62.97; H, 3.89; N, 15.46. Found: C, 63.06; H,
3.97; N, 15.30.
EXPERIMENTAL
Melting points were determined with a WRS-1B digital
melting point apparatus (Shanghai, China) and were uncorrected.
1H NMR spectra was recorded with a Varian Mercury PLUS 600
(600 MHz) spectrometer (Palo Alto, CA) with TMS as the inter-
nal reference and CDCl3 as the solvent, whereas mass spectra
were obtained with a Finnigan TRACEMS2000 spectrometer
(USA) using the EI method. IR spectra were measured by a
Nicolet NEXUS470 spectrometer (ThermoNicoletCorporation,
USA). Elemental analyses were performed with an Elementar
Vario ELШ CHNSO elemental analyzer (Elementar, Germany).
1 and 6 were synthesized by b-keto ester with various hydrazines
or hydroxy amine according to the reported methods [13,14];
4-methyl-1,2,3-thiadiazole-5-carbonyl chloride 2a and 1-[(6-
chloropyridin-3-yl)methyl]-5-methyl-1,2,3-triazol-4-carbonyl chlo-
ride 2b were synthesized by the reported procedures [15,16],
respectively. All of the solvents and materials were reagent grade
and purified as required.
Data for 3e (R1 = CH3, R2 = C6H5). Colorless solid, yield:
87%, mp 215–217ꢀC; 1H NMR (CDCl3, 600 MHz): d 2.57
(s, 3H, CH3), 2.70 (s, 3H, CH3), 5.58 (s, 2H, CH2), 7.31
(t, J = 7.2 Hz, 1H, Ar-H), 7.38 (d, J = 8.4 Hz, 1H, Py-H), 7.46 (t,
J = 7.8 Hz, 2H, ArH), 7.52 (d, J = 8.4 Hz, 1H, Py-H), 7.82 (d,
J = 8.4 Hz, 2H, Ar-H), 8.41 (s, 1H, Py-H), 15.75 (s, 1H, OH);
IR (KBr) υ: 3442 (OH), 3039 (ArH), 1624 (C═O), 1586, 1489,
1452 (Ar) cmÀ1; EIMS (70 eV): m/z 408 (M+, 2.0), 327 (29.8),
253 (15), 207 (17), 147 (29.1), 127 (17.9), 113 (27.8), 99
(39.8), 85 (100), 71 (80.3), 57 (62.5). Anal. Calcd for
C20H17ClN6O2: C, 58.75; H, 4.19; N, 20.56. Found: C, 58.92;
H, 4.28; N, 20.43.
Data for 3f (R1 = CH3, R2 = 4-ClC6H4).
Colorless solid,
General procedure for the synthesis of 4-acyl-2,5-disubstituted-
3-hydroxypyrazoles 3 and 4-aroyl-3-substitutedisoxazol-5-
ones 7. To the stirred solution of 2,5-disubstituted-2,4-dihydro-
pyrazol-3-ones 1 (5mmol) or 3-substituted-4H-isoxazol-5-ones 6
(5mmol) in anhydrous dioxane (15 mL), the powders of Ca(OH)2
(0.59 g, 8 mmol) and CaO (0.11 g, 2 mmol) was added at 80ꢀC.
After the addition was completed, the solution was stirred
under reflux for 20 min. Acyl chloride (5 mmol) in anhydrous
dioxane (5 mL) was added dropwise with strong stirring. After
the addition was completed, the mixture was stirred under
reflux until the reaction was finished (monitored by TLC).
After the mixture was cooled to room temperature, dilute
hydrochloric acid (2 mol/L, 7.5 mL) was added; the mixture
was allowed to stir for 30 min, and water (20 mL) was added.
The solid was collected by filtration and recrystallized from
the mixture of ethanol and water (V/V 1:1) to give 3 or 7 in
68–92% yields.
yield: 83%, mp 184–185ꢀC; 1H NMR (CDCl3, 600 MHz):
d 2.55 (s, 3H, CH3), 2.70 (s, 3H, CH3), 5.59 (s, 2H, CH2), 7.39
(d, J = 7.8 Hz, 1H, Py-H), 7.42 (d, J = 8.4 Hz, 2H, Ar-H), 7.54
(d, J = 8.4 Hz, 1H, Py-H), 7.81 (d, J = 8.4 Hz, 2H, Ar-H), 8.41
(s, 1H, Py-H), 15.95 (s, 1H, OH); IR (KBr) υ: 3435 (OH),
3041 (ArH), 1632 (C═O), 1589, 1573, 1495, 1448 (Ar) cmÀ1
.
Anal. Calcd for C20H16Cl2N6O2: C, 54.19; H, 3.64; N, 18.96.
Found: C, 54.12; H, 3.47; N, 19.07.
Data for 3g (R1 = CH3, R2 = 4-FC6H4).
Light red solid,
yield: 83%, mp 85–86ꢀC; 1H NMR (CDCl3, 600 MHz): d
2.56 (s, 3H, CH3), 2.71 (s, 3H, CH3), 5.59 (s, 2H, CH2),
7.15 (t, J = 8.4 Hz, 2H, Ar-H), 7.38 (d, J = 8.4 Hz, 1H, Py-H),
7.53 (d, J = 8.4 Hz, 1H, Py-H), 7.79 (dd, J = 4.2 Hz,
J = 8.4 Hz, 2H, ArH), 8.41 (s, 1H, Py-H), 15.82 (s, 1H,
OH); IR (KBr) υ: 3427 (OH), 3047 (ArH), 1637 (C═O),
1588, 1568, 1482, 1445 (Ar) cmÀ1
. Anal. Calcd for
Data for 3a (R1 = CH3, R2 = C6H5). Light brown solid, yield:
C20H16ClFN6O2: C, 56.28; H, 3.78; N, 19.69. Found: C,
56.21; H, 3.81; N, 19.75.
1
76%, mp 93–95ꢀC; H NMR (CDCl3, 600 MHz): d 1.96 (s, 3H,
Data for 3h (R1 = C6H5, R2 = C6H5).
Light yellow solid,
CH3), 2.81 (s, 3H, CH3), 7.36 (t, J = 6.6 Hz, 1H, Ar-H), 7.50
yield: 84%, mp 160–162ꢀC; 1H NMR (CDCl3, 600 MHz): d
2.61 (s, 3H, CH3), 5.55 (s, 2H, CH2), 7.33–7.41 (m, 5H, Ar-H),
7.47–7.53 (m, 3H, Ar-H), 7.63 (d, J = 7.8 Hz, 2H, Py-H), 7.90
(d, J = 9.0 Hz, 2H, Ar-H), 8.39 (s, 1H, Py-H), 15.94 (s,
(t, J = 8.4Hz, 2H, Ar-H), 7.82 (s, 2H, Ar-H); IR (KBr) υ: 3176
(OH), 3048 (ArH), 1682 (C═O), 1615, 1552, 1500 (Ar) cmÀ1
.
Anal. Calcd for C14H12N4O2S: C, 55.99; H, 4.03; N, 18.65.
Found: C, 55.83; H, 4.15; N, 18.71.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

H. Song, W.-B. Feng, F. Cheng, and D.-Q. Shi
Vol 000
1H, OH); IR (KBr) υ: 3431 (OH), 3044 (ArH), 1629 (C═O),
1591, 1570, 1493, 1450 (Ar) cmÀ1; EIMS (70 eV): m/z 470
(M+, 3.5), 340 (48.3), 284 (23.4), 177 (100), 161 (57.9), 149
(47.3), 121 (18.8), 91(16.5). Anal. Calcd for C25H19ClN6O2: C,
63.76; H, 4.07; N, 17.85. Found: C, 63.91; H, 4.24; N, 17.97.
Data for 7a (R3 = CH3, Ar = C6H5). Colorless solid, yield:
(m, 6H, Ar-H), 7.59 (d, J = 7.8 Hz, 2H, Ar-H); IR (KBr) υ:
3131 (ArH), 1784, 1697 (C═O), 1646, 1597, 1472 (Ar) cmÀ1
;
EIMS (70 eV): m/z 299 (M+, 2), 141 (33), 139 (100), 111 (22),
75 (13), 44 (6). Anal. Calcd for C16H10ClNO3: C, 64.12; H,
3.36; N, 4.67. Found: C, 64.04; H, 3.41; N, 4.59.
Data for 7i (R3 = C6H5, Ar = 4-FC6H4). Light yellow solid,
yield: 72%, mp 113–115ꢀC; 1H NMR (CDCl3, 600 MHz): d 5.78
(s, 1H, CH), 7.20 (d, J = 7.8 Hz, 2H, Ar-H), 7.49–7.56 (m, 5H,
Ar-H), 8.02 (dd, J = 4.2 Hz, J = 7.8 Hz, 2H, Ar-H); IR (KBr) υ:
1
75%, mp 76–78ꢀC; H NMR (CDCl3, 600 MHz): d 2.70 (s, 3H,
CH3), 5.41 (s, 1H, CH), 7.48–7.50 (m, 2H, Ar-H), 7.61
(t, J = 7.2 Hz, 1H, Ar-H), 7.89 (d, J = 7.8 Hz, 2H, Ar-H); IR
(KBr) υ: 3126 (ArH), 1785, 1696 (C═O), 1595, 1501 (Ar)
cmÀ1; EIMS (70 eV): m/z 203 (M+, 2), 105 (100), 77 (58), 51
(12). Anal. Calcd for C11H9NO3: C, 65.02; H, 4.46; N, 6.89.
Found: C, 64.95; H, 4.50; N, 6.77.
3138 (ArH), 1777, 1695 (C═O), 1650, 1593, 1478 (Ar) cmÀ1
.
Anal. Calcd for C16H10FNO3: C, 67.84; H, 3.56; N, 4.94.
Found: C, 68.96; H, 3.39; N, 5.02.
Herbicidal activity (in vitro). The herbicidal evaluation of
compounds 3 and 7 were carried out in the laboratory of
biological activities test, State Key Laboratory of Elemento-
organic Chemistry, Nankai University, China. Compounds 3
and 7 were determined with B. campestris L. and E. crus-galli
as samples of annual dicotyledonous and monocotyledonous
plants, respectively, using a previously reported procedure [16].
For all of the bioassay tests, each treatment was repeated twice.
Data for 7b (R3 = CH3, Ar = 2-ClC6H4). Light yellow solid,
yield: 79%, mp 111–113ꢀC; 1H NMR (CDCl3, 600 MHz): d 2.71
(s, 3H, CH3), 5.43 (s, 1H, CH), 7.38 (t, J = 7.8 Hz, 1H, Ar-H),
7.47 (d, J = 7.2 Hz, 3H, Ar-H); IR (KBr) υ: 3131 (ArH), 1789,
1692 (C═O), 1590, 1518 (Ar) cmÀ1
. Anal. Calcd for
C11H8ClNO3: C, 55.60; H, 3.39; N, 5.89. Found: C, 55.44; H,
3.35; N, 5.98.
Data for 7c (R3 = CH3, Ar = 3-ClC6H4). White solid, yield:
Treatment.
The emulsions of purified compounds were
1
92%, mp 89–91ꢀC; H NMR (CDCl3, 600 MHz): d 2.71 (s, 3H,
prepared by dissolving them in N,N-dimethylformamide (100 mL)
with the addition of Tween 20 (2mL). The mixture of the same
amount of water, N,N-dimethylformamide, and Tween 20 was
used as control.
CH3), 5.45 (s, 1H, CH), 7.44 (t, J = 7.8 Hz, 1H, Ar-H), 7.58
(d, J = 8.4 Hz, 1H, Ar-H), 7.79 (d, J = 7.8 Hz, 1H, Ar-H), 7.87
(s, 1H, Ar-H); IR (KBr) υ: 3132 (ArH), 1798, 1699 (C═O),
1646, 1598, 1571 (Ar) cmÀ1; EIMS (70 eV): m/z 237 (M+, 6),
141 (31), 139 (100), 111 (28), 75 (17). Anal. Calcd for
C11H8ClNO3: C, 55.60; H, 3.39; N, 5.89. Found: C, 55.76; H,
3.51; N, 5.94.
Inhibition of the root-growth of rape (B. campestris L.). Rape
seeds were soaked in distilled water for 4 h before being placed on a
filter paper in a 6-cm Petri plate, to which 2 mL of inhibitor solution
had been added in advance. Usually, 10 seeds were used on each
plate. The plate was placed in a dark room and allowed to germinate
for 72 h at 28Æ 1ꢀC. The lengths of 10 rape roots selected from
each plate were measured, and the means were calculated. The
percentage inhibition was used to describe the control efficiency
of the compounds. The herbicidal activity was listed in Table 1.
Inhibition of the seedling growth of barnyard grass (E.
crus-galli). Ten E. crus-galli seeds were placed into a 50-mL
cup covered with a layer of glass beads and a piece of filter paper
at the bottom, to which 6 mL of inhibitor solution had been added
in advance. The cup was placed in a bright room, and the seeds
were allowed to germinate for 72 h at 28 Æ 1ꢀC. The heights of
the above-ground parts of the seedlings in each cup were
measured, and the means were calculated. The percentage
inhibition was used to describe the control efficiency of the
compounds. The herbicidal activity is also listed in Table 1.
Data for 7d (R3 = CH3, Ar = 4-ClC6H4). White solid, yield:
91%, mp 136–138ꢀC; 1H NMR (CDCl3, 600 MHz): d 2.71 (s, 3H,
CH3), 5.43 (s, 1H, CH), 7.48 (d, J = 7.8 Hz, 2H, Ar-H), 7.87 (d,
J = 7.8 Hz, 2H, Ar-H); IR (KBr) υ: 3130 (ArH), 1794, 1675
(C═O), 1640, 1585, 1577 (Ar) cmÀ1
. Anal. Calcd for
C11H8ClNO3: C, 55.60; H, 3.39; N, 5.89. Found: C, 55.51; H,
3.49; N, 5.63.
Data for 7e (R3 = CH3, Ar = 2-FC6H4). White solid, yield:
76%, mp 120–121ꢀC; 1H NMR (CDCl3, 600 MHz): d 2.71
(s, 3H, CH3), 5.43 (s, 1H, CH), 7.37–7.40 (m, 1H, Ar-H), 7.47
(t, J = 7.2 Hz, 3H, Ar-H); IR (KBr) υ: 3142 (ArH), 1776, 1705
(C═O), 1645, 1608, 1476 (Ar) cmÀ1; EIMS (70 eV): m/z 221
(M+, 3), 141 (29), 139 (100), 111 (32), 75 (19), 44 (36). Anal.
Calcd for C11H8FNO3: C, 59.73; H, 3.65; N, 6.33. Found: C,
59.92; H, 3.49; N, 6.41.
Data for 7f (R3 = CH3, Ar = 4-FC6H4). White solid, yield:
89%, mp 130–132ꢀC; 1H NMR (CDCl3, 600 MHz): d 2.70
(s, 3H, CH3), 5.42 (s, 1H, CH), 7.18 (d, J = 7.8 Hz, 2H, Ar-H),
7.97 (dd, J = 5.4 Hz, J = 7.8 Hz, 2H, Ar-H); IR (KBr) υ: 3144
(ArH), 1771, 1708 (C═O), 1641, 1605, 1482 (Ar) cmÀ1. Anal.
Calcd for C11H8FNO3: C, 59.73; H, 3.65; N, 6.33. Found: C,
59.61; H, 3.59; N, 6.27.
Acknowledgments. This work was supported by the Natural Science
Foundation of China (Grant No. 20872046), Natural Science
Foundation of Wuhan Municipal Education Bureau (No. 2010019),
and the Fundamental Research Funds for the Central Universities
(No. CCNU09A02013).
Data for 7g (R3 = CH3, Ar = 4-CH3C6H4).
Light yellow
1
solid, yield: 77%, mp 85–87ꢀC; H NMR (CDCl3, 600 MHz): d
2.44 (s, 3H, CH3), 2.70 (s, 3H, CH3), 5.39 (s, 1H, CH), 7.29
(d, J = 7.8 Hz, 2H, Ar-H), 7.82 (d, J = 8.4 Hz, 2H, Ar-H); IR
(KBr) υ: 3128 (ArH), 1786, 1692 (C═O), 1638, 1601, 1478
(Ar) cmÀ1; EIMS (70 eV): m/z 217 (M+, 1.5), 119 (100), 91
(45), 65 (13), 44 (7). Anal. Calcd for C12H11NO3: C, 66.35; H,
5.10; N, 6.45. Found: C, 66.29; H, 5.01; N, 6.37.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

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