Synthesis and herbicidal activities of novel 3-(α-hydroxymethylene) pyrrolidine-2,4-dione derivatives containing a cyclopropane moiety

Article abstract of DOI:10.1002/jhet.909

A variety of novel 3-(α-hydroxymethylene)pyrrolidine-2,4-dione derivatives containing a cyclopropane moiety were designed and synthesized in satisfactory yields. Their structures were confirmed by ¹H NMR and HRMS. The bioassays indicated that most of the title compounds displayed some extent herbicidal activities at 100 mg/mL.

Full text of DOI:10.1002/jhet.909

2
02
Synthesis and Herbicidal Activities of Novel 3-(a-Hydroxymethylene)
Vol 50
pyrrolidine-2,4-dione Derivatives Containing a Cyclopropane Moiety
a
a
a
a
b
a
You-quan Zhu, * Jin Zhang, Yan-wei Yuan, Li-fen Xie, Hai-zhen Xu, Xiao-mao Zou, *
a
and Hua-zheng Yang
a
State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Tianjin 300071,
People’s Republic of China
College of Chemistry, Tianjin Normal University, Tianjin 300387, People’s Republic of China
b
*
E-mail: zyq8165@nankai.edu.cn
Received January 23, 2011
DOI 10.1002/jhet.909
Published online 20 March 2013 in Wiley Online Library (wileyonlinelibrary.com).
O
3
N
R3
1
R NHCH CO C H (9)
R1
2
2
2
5
OC H
2
5
R1
R2
R2
2 CH OH,CH ONa
O
O
3
3
8
O
O
5
A variety of novel 3-(a-hydroxymethylene)pyrrolidine-2,4-dione derivatives containing a cyclopropane
1
moiety were designed and synthesized in satisfactory yields. Their structures were confirmed by H NMR
and HRMS. The bioassays indicated that most of the title compounds displayed some extent herbicidal
activities at 100 mg/mL.
J. Heterocyclic Chem., 50, 202 (2013).
INTRODUCTION
syntheses via acetoacetic esters [11], via Meldrum’s acid
[
12,13], and via mixed malonic esters [14] are practically
Heterocyclic compounds are significant in modern
organic and agrochemical chemistry due to their presence
in a majority of well-known pharmaceutical preparations
useful, although not always satisfactory in yield. In this
paper, considering the properties of acyl chlorides (6) and
the starting materials’ availability, b-keto esters (8) were
synthesized through a general and versatile method based
on the noteworthy reactivity of Meldrum’s acid.
Compound 5 can be synthesized by acetylation of
pyrrolidine-2,4-dione followed by the aroyl group’s
migration [15] or reaction of aroyl acetates with N-alkyl
aminoacetates [16]. We preferred the latter method to prepare
the target products 5 for its less toxic reagents and greater
convenience. Intermediate 8 was reacted with 9 in refluxing
absolute xylene to give the target compound 5 (Scheme 1).
This reaction was assumed to go through a nucleophilic
addition/elimination reaction. During this process, an inter-
mediate amide’s formation and a cyclizative condensation
were involved.
Structure–activity relationship. A series of the related
target products 5 were prepared and their herbicidal
activities were tested, and the results listed in Table 4
shows that most of the target products 5 exhibited a
higher inhibition rate for Brassica campestris than that
for E. crus-galli at 100 mg/mL and this result indicated
the selectivity of this kind compounds was effected by
the halogen’s introduction(such as 5s).
[1]. For these reasons, we have for a long time been inter-
ested in the synthesis of new heterocycles of potential
pharmaceutical value. Recently, our attentions were focused
on the preparation of compound 1 through a modification
of the natural product 2 [2–7], which was inhibitory to-
ward 4-hydroxyphenylpyruvate dioxygenase (HPPD, EC
1
.13.11.27) with an IC = 18 mM [8]. The bioassay results
50
1
showed that when R was electron-donating, compound 1
exhibited better herbicidal activities [3–7]. In particular,
1
2
3
when R , R , and R were 2,4-dimethoxy, iso-propyl, and
hydrogen, respectively, compound 1 provided 93% control
of Echinochloa crus-galli at pre-emergence at 187.5 g/ha.
It was also noticed that a-ketoisocaproate (3) serve as
natural substrates for HPPD [9]. In light of these findings
and subsequent comparisons of the molecular structures of
both HPPD enzyme substrates and triketone type inhibitors,
Lin and co-workers reported 2- cyclopropanoylcyclohexane-
1
,3-dione(4) exhibited higher in vitro inhibition activity
against HPPD (IC = 6 mM) [10]. In order to find valuable
5
0
new lead compounds with high herbicidal activities,
compounds 5 were designed and synthesized through
replacement of the aryl group of compound 1 by different
cyclopropyl groups. In this paper, we described the synthesis
and herbicidal activities of some 3-[(a-hydroxy(cyclopropyl)
methylene] pyrrolidine-2,4-diones 5 (Figure 1, Scheme 1).
3
For B.campestris at 100 mg/mL, when the substituent R
was iso-propyl, propyl, allyl, and cyclo-propyl, the
corresponding compounds 5 (except for 5m, 5p) generally
exhibited better herbicidal activity than those compounds 5
(
3
R = butyl and sec-butyl) 2), as a result of substituent steric
RESULTS AND DISCUSSION
hindrance.
Preparations. Among the many methods for synthesizing
b-keto esters of the type RCOCH CO C H , three classical
For E. crus-galli at 100 mg/mL, most of the target
compounds 5 exhibited moderate herbicidal activity, but
2
2 2 5
©
2013 HeteroCorporation

March 2013
203
Synthesis and Herbicidal Activities of Novel 3-(a-Hydroxymethylene)
pyrrolidine-2,4-dione Derivatives
O
O
O
R2
Compounds 8a–8d were synthesized as the literature
described [12,13,17,18]. Meldrum’s acid (0.01 M) was dissolved
in 75 mL of methylene chloride, and the reaction mixture was
HO
O
N
NH
CO -
2
R1
R3
O
ꢀ
placed under nitrogen and brought to 0 C with an ice bath;
O
3
pyridine (0.02M) was then added by means of a dropping funnel.
The appropriate acid chloride (0.01M) was added over a 30-min
period to the vigorously stirred mixture. After the final addition,
the solution was allowed to rise to room temperature and allowed
to stand for 3 h. The reaction was monitored by TLC (silica gel).
Upon termination, the mixture was then washed with 30mL of
4 N HCl, 2% sodium bicarbonate, and distilled water saturated
2
1
O
O
OH
O
R3
HO
N
R2
R1
O
4
5
4
with sodium chloride. The dried (MgSO ) organic phase was
filtered and crude 7a–7d was obtained by solvent removal in
vacuo and not further purified. The residue crude 7a–7d was
resolved in 10 mL of ethanol and refluxed for 2 h. The solvent
was removed, and the residue was purified by flash silica gel
Figure 1. Chemical structures of compounds 1–5.
Scheme 1
ꢀ
O
chromatography using petroleum ether (60–90 C) and ethyl
O
acetate as the eluent to yield 8a–8d. All of the compounds were
identified by H NMR spectroscopy. Their yields of compounds
8a–8d are listed in Table 1.
O
1
O
R1
R2
Cl
O
R1
O
O
R2
General synthetic procedure for 5a–5s. Compounds 5a–5s
were synthesized as the literature described [6,7,16].
O
O
O
6
7
A mixture of 8 (3 mmol) and 9 (3.13 mmol) in dry xylene
ꢀ
(
5 mL) was heated at 125–130 C with stirring for 24 h. The
C H OH
R1
R2
2
5
OC H
2
5
cooled solution was added to methanolic CH ONa, prepared from
3
O
O
Na metal (3.35 mmol) and methanol (4 mL) at room temperature
with stirring. After the aforementioned mixture was stirred at
room temperature for 48 h, water (20 mL) was added to the reac-
tion mixture and the organic layer was separated and extracted
twice with water. The original water layer and the extracts were
combined and acidified to pH 2–3 with 2N HCl under cooling.
The acidic solution was extracted three times with chloroform
8
O
3
R3
1
R NHCH CO C H (9)
N
2
2 2 5
R1
R2
2
CH OH,CH ONa
3 3
O
O
5
(
30 mL), and the extracts were washed with saturated brine and
1
2
3
when R , R , and R were methyl, methyl, and iso-propyl,
respectively, compound 5s showed about 89% inhibiting
rate. Considering that compound 5s also possessed
excellent herbicidal activity (about 95%) for B.campestris,
then dried over Na SO . The solvent was removed under reduced
2
4
pressure to give crude product 5, which was purified by flash
column chromatography on silica gel, using ethyl acetate–petroleum
ether as the eluant to afford the pure target product. The melting
points and yields of compounds 5a–5s are listed in Table 2, and
1
2
compound 5 (R , R = methyl) will be our next research
emphasis.
1
their H NMR are listed in Table 3.
Bioassays. The herbicidal activities of the title compounds
(5a–5s) were evaluated using a previously reported procedure [4,5].
Treatment. The emulsions of purified compounds were prepared
by dissolving them in 100 mL of N,N-dimethylformamide with the
addition of a little Tween 20 and proper water. There were two
In summary, a variety of novel 3-(a-hydroxymethylene)
pyrrolidine-2,4-dione derivatives were designed and syn-
thesized in satisfactory yields and the bioassays indicated
that most of the title compounds displayed some extent
herbicidal activities.
EXPERIMENTAL
Table 1
1
Yields and H NMR data of compound 8.
All chemicals were purchased from commercial sources and
purified by recrystallization or distillation. NMR spectra were
recorded on a Bruker DPX 400 spectrometer (Bruker BioSpin
AG industriestrasse 26CH-8117, Fallanden, Switzerland.); data
1
2
ꢀ
R
R
Yield (%)
mp ( C)
8
8
a
b
Cl
Br
Cl
Br
88
82
liquid
liquid
1
for H are reported as follows: chemical shift (ppm), integration,
multiplicity (s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet;
and br, broad), coupling constant (Hz), and number. The melting
points were determined on an X-4 binocular microscope melting
point apparatus (Beijing Tech Instruments Co., Beijing, China)
and are uncorrected. High resolution mass spectra were recorded
on a VARIAN 7.0 T direct inlet instrument (IonSpec Corpora-
tion, Lake Forest, USA). Solvents were fractionally distilled
before use.
1.21 (s, 3H), 1.28–1.31 (m, 6H), 2.12 (t, J = 8.2 Hz, 1H), 2.25
(d, J = 8.0 Hz, 1H), 3.54 (q, J = 15.1 Hz, 2H), 4.21 (q, J = 7.1 Hz,
2H),6.80 (d, J = 8.5 Hz, 1H)
8
8
c
d
CH
CF
3
CH
Cl
3
44
85
liquid
liquid
3
1
(
.16 (s, 3H), 1.22 (t, J = 7.1 Hz, 3H), 1.27 (s, 3H), 2.24
t, J = 8.5 Hz, 1H), 2.31 (d, J = 8.0 Hz, 1H), 3.47 (q, J = 14.7 Hz,
H), 4.14 (q, J = 7.1 Hz, 2H), 6.88 (d, J = 9.1 Hz, 1H)
2
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

2
04
Y. Q. Zhu, J. Zhang, Y. W. Yuan, L. F. Xie, H. Z. Xu, X. M. Zou, and H. Z. Yang
Vol 50
Table 2
Melting points, yields, and mass data of compounds 5a–5s.
1
2
3
ꢀ
R
R
R
mp/ C
Yield (%)
MS (ESI, m/z):
À
À
5
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
Cl
Cl
Cl
Cl
Cl
Cl
Br
Br
Br
Br
Br
Br
Cl
Cl
Cl
Cl
Cl
Cl
CH
Cl
Cl
Cl
Cl
Cl
Cl
Br
Br
Br
Br
Br
Br
C
iso–C
cyclo–C
allyl
C
sec-C
C
iso–C
cyclo–C
allyl
C
sec-C
C
iso-C
cyclo-C
allyl
C
sec-C
iso-C
3
H
7
liquid
113–114
liquid
liquid
liquid
liquid
liquid
liquid
liquid
liquid
liquid
liquid
54–55
82–84
liquid
liquid
liquid
72–74
liquid
58
58
18
58
47
56
43
51
27
50
30
28
60
54
37
41
32
45
54
330.0675[(M À H) ,100%]
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
3
H
7
330.0669[(M À H) ,100%]
À
3
H
5
5
5
328.0515[(M À H) ,100%]
À
328.0513[(M À H) ,100%]
À
4
H
9
344.0826[(M À H) ,100%]
À
4
H
9
344.0826[(M À H) ,100%]
À
+
3
H
7
419.9639[(M À H) ,100%]
3
H
7
443.9587[(M + Na) ,100%]
À
3
H
417.9485[(M À H) ,100%]
À
417.9482[(M À H) ,100%]
À
4
H
9
433.9795[(M À H) ,100%]
À
4
H
9
435.9931[(M + H) ,100%]
À
+
CF
CF
CF
CF
CF
CF
3
3
H
7
364.0930[(M À H) ,100%]
3
3
3
3
3
3
H
7
388.0898[(M + Na) ,100%]
À
3
H
362.0772[(M À H) ,100%]
À
362.0771[(M À H) ,100%]
À
4
H
9
378.1089[(M À H) ,100%]
À
4
H
H
9
378.1089[(M À H) ,100%]
À
3
CH
3
3
7
290.1762[(M À H) ,100%]
Table 3
1
H NMR of compounds 5a–5s.
1
H NMR d (ppm)
5
a
0.94 (t, J = 7.3 Hz, 3H), 1.35 (s,3H), 1.36(s,3H), 1.56–1.67(m,2H), 2.42(t, J = 8.8 Hz,1H), 3.23(d, J = 8.5 Hz, 1H), 3.40 (t, J = 7.2 Hz,2H), 3.72
s, 2H,),6.23 (d, J = 9.3 Hz,1H)
1.14 (s, 3H), 1.15 (s, 3H), 1.28 (d, J = 5.4 Hz, 6H), 2.34 (t, J = 8.7 Hz, 1H), 3.15 (d, J = 8.4 Hz, 1H),3.61 (s, 2H), 4.38–4.45 (m, J = 6.6 Hz, 1H),
.16 (d, J = 9.1 Hz, 1H)
(
5
b
6
5
5
c
d
0.72–0.80 (m, 4H), 1.26 (s, 3H), 1.28 (s, 3H), 2.34 (t, J= 9.0 Hz, 1H), 2.62–2.68 (m, 1H), 3.14 (d, J= 8.4 Hz, 1H), 3.61 (s, 2H), 6.15 (d, J=9.1Hz, 1H)
1.35 (s, 3H), 1.36 (s, 3H), 2.43 (t, J = 8.8 Hz, 1H), 3.24 (d, J = 8.4 Hz, 1H), 3.71 (s, 2H), 4.04–4.06 (m, 2H), 5.19–5.22 (m, 1H), 5.26–5.28 (m, 1H),
5
.73–5.81 (m, 1H), 6.22 (d, J = 9.2 Hz, 1H)
0.96 (t, J = 7.3 Hz, 3H), 1.31–1.40 (m, 2H), 1.35 (s, 3H), 1.36 (s, 3H), 1.53–1.60 (m, 2H), 2.42 (t, J = 8.7 Hz, 1H), 3.23 (d, J = 8.5 Hz, 1H ), 3.44
t, J = 7.2 Hz, 2H), 3.72 (s, 2H), 6.23 (d, J = 9.2 Hz, 1H)
0.82 (t, J = 7.4 Hz, 3H), 1.12 (d, J = 6.7 Hz, 3H), 1.25–1.29 (m, 6H), 1.42–1.51 (m, 2H), 2.34 (t, J = 8.8 Hz, 1H), 3.16 (d, J = 8.5 Hz, 1H),
.49–3.62 (m, 2H), 4.11–4.20 (m, 1H), 6.15–6.19 (d-d, J = 4.8, J = 9.2, 1H)
0.95 (t, J= 7.4 Hz, 3H), 1.34 (s, 3H), 1.36 (s, 3H), 1.57–1.66 (m, J= 7.3 Hz, 2H), 2.34 (t, J= 8.7 Hz, 1H), 3.24 (d, J= 8.4 Hz, 1H), 3.40 (t, J= 7.3 Hz, 2H),
.72 (s, 2H), 6.75 (d, J= 8.9 Hz, 1H)
1.14 (s, 3H), 1.15 (s, 3H), 1.26–1.28 (m, 6H), 2.26 (t, J = 8.6 Hz, 1H), 3.16 (d, J = 8.4 Hz, 1H), 3.60(s, 2H), 4.37–4.46 (m, J = 6.7 Hz,1H), 6.68
d, J = 8.8 Hz, 1H)
5
5
5
5
e
(
f
3
1
2
g
h
3
(
5
5
i
j
0.72–0.80 (m, 4H), 1.26 (s, 3H), 1.28 (s, 3H), 2.26 (t, J= 8.6 Hz, 1H), 2.64–2.70 (m, 1H), 3.15 (d, J= 8.5 Hz, 1H), 3.60 (s, 2H), 6.66 (d, J=8.8Hz, 1H)
1.34 (s, 3H), 1.36 (s, 3H), 2.37 (t, J = 8.6 Hz, 1H), 3.25 (d, J = 8.4Hz, 1H), 3.71 (s, 2H), 4.04–4.06(m, 2H), 5.19–5.22 (m, 1H), 5.26–5.29 (m, 1H),
5
.72–5.81 (m, 1H), 6.74 (d, J = 8.8 Hz,1H)
0.88 (t, J = 7.3 Hz, 3H), 1.24–1.33 (m, 8H), 1.46–1.53 (m, 2H), 2.27 (t, J = 8.6 Hz, 1H), 3.16 (d, J = 8.4 Hz, 1H), 3.37 (t, J = 7.1 Hz, 2H), 3.65
s, 2H), 6.67 (d, J = 8.9 Hz, 1H)
0.83 (t, J = 7.4 Hz, 3H), 1.12 (d, J = 6.5 Hz, 3H), 1.27–1.29 (m, 6H), 1.42–1.51 (m, 2H), 2.26 (t, J = 8.6 Hz, 1H), 3.17 (d, J = 8.5 Hz, 1H),
.50–3.64 (m, 2H), 4.78–4.82 (m, 1H), 6.69 (d, J = 5.3 Hz, 1H)
0.95 (t, J = 7.3 Hz, 3H), 1.39 (s, 3H), 1.41 (s, 3H), 1.56–1.68 (m, J = 7.2 Hz, 2H), 2.53 (t, J = 9.0 Hz,1H), 3.36 (d, J = 8.4 Hz, 1H), 3.41
t, J = 7.2 Hz, 2H), 3.74 (s, 2H), 6.89 (d, J = 9.6 Hz, 1H)
1.14 (s, 3H), 1.15 (s, 3H), 1.31 (d, 6H), 2.44 (t, J = 8.8 Hz, 1H), 3.27 (d, J = 8.4 Hz, 1H), 3.62 (s, 2H),4.38–4.44 (m, J = 6.5 Hz, 1H),
.81 (d, J = 9.6 Hz, 1H)
0.72–0.81 (m, 4H), 1.30 (s, 3H), 1.32 (s, 3H), 2.44 (t, J = 9.0 Hz, 1H), 2.64–2.70 (m, 1H), 3.26 (d, J = 8.4 Hz, 1H), 3.62 (s, 2H), 6.79
d, J = 9.6 Hz, 1H)
1.30 (s, 3H), 1.33 (s, 3H), 2.46 (t, J = 9.0 Hz, 1H), 3.28 (d, J = 8.42 Hz, 1H), 3.64 (s, 2H), 3.96–3.98 (m, 2H), 5.11–5.20 (m, 1H), 5.63–5.73
m, 1H), 6.80 (d, J = 9.6 Hz, 1H)
0.96 (t, J = 7.32 Hz, 3H), 1.29–1.41 (m, 8H), 1.53–1.60 (m, 2H), 2.52 (t, J = 9.0 Hz, 1H), 3.35 (d, J = 8.41 Hz, 1H), 3.45 (t, J = 7.40 Hz, 2H),
.74 (s, 2H), 6.88 (d, J = 9.6 Hz, 1H)
0.83 (t, J = 7.4 Hz, 3H), 1.12 (d, J = 6.8 Hz, 3H), 1.27–1.29 (m, 6H), 1.41–1.51 (m, 2H), 2.44 (t, J = 8.9 Hz, 1H), 3.28 (d, J = 8.5 Hz, 1H),
.51–3.63 (m, 2H), 4.11–4.20 (m, 1H), 6.80–6.84 (m, 1H)
1.19 (s, 3H), 1.21 (s, 3H), 1.30 (d, J = 18.3 Hz, 6H), 1.69 (s, 3H), 1.72 (s, 3H), 2.51 (t, J = 6.7 Hz, 1H), 2.76 (d, J = 5.6 Hz, 1H), 3.65 (s, 2H),
.46–4.53 (m, J = 6.8 Hz, 1H), 5.02 (d, J = 7.9 Hz, 1H)
5
5
5
5
5
5
5
5
5
k
(
l
3
m
n
o
p
q
r
(
6
(
(
3
3
s
4
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

March 2013
Synthesis and Herbicidal Activities of Novel 3-(a-Hydroxymethylene)
205
pyrrolidine-2,4-dione Derivatives
Table 4
Herbicidal activity of compounds 5a–5s (percent inhibition; concentration
00 mg/mL).
inhibition was used to describe the control efficiency of the
compounds. The herbicidal activity is summarized in Table 4.
1
Brassica campestris
Echinochloa crus-galli
Acknowledgments. We are grateful for financial support by the
National Basic Research Program of China (No. 2010CB126103)
and the National Natural Science Foundation of China
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
94.8
94.8
92.2
94.8
75.9
87.0
74.0
83.7
79.8
92.8
60.3
66.8
0
92.2
85.7
0
5.7
60.3
94.8
30.0
44.3
42.0
44.3
41.4
40.0
35.0
22.0
15.0
74.1
12.8
12.8
39.2
32.3
43.1
35.0
33.1
23.7
89.4
(
NO.20772066, NO.21072108).
REFERENCES AND NOTES
[1] Graupner, P. R.; Carr, A.; Clancy, E.; Gilbert, J.; Bailey, K. L.;
Derby, J.-A.; Clifford, B. C. J Nat Prod 2003, 66, 1558.
[
[
2] Wu, Y. C.; Hu, F. Z.; Yang, H. Z. Chin J Pestic Sci 2001, 3(3), 1.
3] Zhu, Y. Q.; Si, X. K.; Zou, X. M.; Liu, B.; Yang, H. Z. Chin J
Org Chem 2007, 27, 385.
[4] Zhu, Y. Q.; Zou, X. M.; Hu, F. Z.; Yao, C. S.; Liu, B.; Yang,
H. Z. J Agric Food Chem 2005, 53, 9566.
[5] Zhu, Y. Q.; Liu, P.; Si, X. K.; Zou, X. M.; Liu, B.; Song, H. B.;
Yang, H. Z. J Agric Food Chem 2006, 54, 7200.
[6] Zhu, Y. Q.; Yao, C. S.; Zou, X. M.; Hu, F. Z.; Liu, B.; Yang,
H. Z. Molecules 2005, 10, 427.
[7] Zhu, Y. Q.; Hu, F. Z.; Zou, X. M.; Yao, C. S.; Liu, B.; Li, Y.
H.; Yang, H. Z. Chin J Org Chem 2005, 25, 419.
[8] Meazza, G.; Scheffler, B. E.; Tellez, M. R.; Rimando, A. M.;
Romagni, J. G.; Duke, S. O.; Nanayakkara, D.; Khan, I. A.; Abourashed,
E. A.; Dayan, F. E. Phytochemistry 2002, 60, 281.
replicates for each treatment. The mixture of the same amount of
water, N,N-dimethylformamide and Tween 20 was used as control.
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, 15 seeds
were used on each plate. The plate was placed in a dark room
[
9] Baldwin, J. E.; Crouch, N. P.; Lee, M.-H.; MacKinnon, C. H.;
Zhang, Z. H. Bioorg Med Chem Lett 1996, 6, 1503.
10] Lin, Y. L.; Wu, C. S.; Lin, S. W.; Yang, D. Y. Bioorg Med
[
Chem Lett 2000, 10, 843.
[11] Shriner, R. L.; Schmidt, A. G.; Roll, L. J. ‘Organic Syntheses’,
Collect. Vol. 2, Wiley, New York. N.Y., 1943, p 266; Guha, M.and
Nasipuri, D. ‘Organic Syntheses’, Collect. Vol. 5, 1973, p 384; Viscontini M.
and Merckling, N. Helv Chim Acta 1952, 35, 2280.
ꢀ
and allowed to germinate for 65 h at 28 (Æ1) C. The lengths of
[
[
12] Yuji O.; Kiyoshi S.; Osamu Y. J Org Chem 1978, 43(10), 2087.
13] Frank D. M.; Giles D. M. Jr.; Richard T. B. J Agric Food
1
0 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 is summarized in Table 4.
Chem 1989, 37(2), 501.
[14] (a) Breslow, D. S.; Baumgarten, E.; Hauser, C. R. J Am Chem
Soc, 1944, 66, 1286; (b) Taylor, E. C.; McKillop, A. Tetrahedron 1967,
23, 897; (c) Bowman, R. E.; Fordham, W. D. J Chem Soc, 1951, 2758;
Inhibition of the seedling growth of barnyard grass
(
d) Pichat, L.; Beaucout, J.-P. Synthesis 1973, 537.
15] Heather, J. B.; Milano, P. D. Acylated diketonic compounds.
EP 0186117, 1986.
(
E. crus-galli L. BeauV). 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 5 mL of inhibitor solution
had been added in advance. The cup was placed in a bright room,
[16] Matsuo, K.; Kitaguchi, I.; Takata, Y.; Tanaka, K. Chem Pharm
Bull 1980, 28, 2494.
ꢀ
and the seeds were allowed to germinate for 65h at 28 (Æ1) C.
[17] Jiang, H.; Zhang, J. M.; Du, W. Q.; Zhu, S. Z. Chin J Org
The heights of the aboveground parts of the seedlings in each
cup were measured and the means calculated. The percentage
Chem 2007, 25, 86.
[18] David D.; Sidney A. B. J Am Chem Soc 1948, 70, 3426.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

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