Synthesis and herbicidal activity of O,O-dialkyl N-[2-(5,7-dimethyl-[1,2,4] triazolo[1,5-a]pyrimidin-2-yloxy)benzoxyl]-1-amino-1-substitutedbenzyl phosphonates

Article abstract of DOI:10.1002/jhet.292

(Chemical Equation Presented) A series of novel 1,2,4-triazolo[1,5-a] pyrimidine derivatives containing an α-amino phosphonate moiety 5 were designed and synthesized by the multi-step reactions. Their structures were clearly confirmed by spectroscopic data (IR, ¹H NMR, ³¹P NMR, MS) and elemental analysis, compound 5b was further determined by X-ray diffraction crystallography. The results of preliminary bioassay indicated that some of the title compounds 5 possessed moderate herbicidal activities against dicotyledonous plants (Brassica campestris L) at the concentration of 100 mg/L. For example, compound 5i possessed 92.0% inhibitory activity against B. campestris L and showed better activity than that of the commercialized herbicide Bispyribac-sodium; however, compounds 5 displayed weak herbicidal activity at the concentration of 10 mg/L.

Full text of DOI:10.1002/jhet.292

162
Synthesis and Herbicidal Activity of O,O-Dialkyl N-[2-(5,7-
dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yloxy)benzoxyl]-1-
amino-1-substitutedbenzyl Phosphonates
Vol 47
Wu Tang and De-Qing Shi*
Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of
Chemistry, Central China Normal University, Wuhan 430079, Hubei, People’s Republic of China
*E-mail: chshidq@mail.ccnu.edu.cn
Received July 5, 2009
DOI 10.1002/jhet.292
Published online 8 January 2010 in Wiley InterScience (www.interscience.wiley.com).
A series of novel 1,2,4-triazolo[1,5-a]pyrimidine derivatives containing an a-amino phosphonate moi-
ety 5 were designed and synthesized by the multi-step reactions. Their structures were clearly confirmed
1
by spectroscopic data (IR, H NMR, 31P NMR, MS) and elemental analysis, compound 5b was further
determined by X-ray diffraction crystallography. The results of preliminary bioassay indicated that
some of the title compounds 5 possessed moderate herbicidal activities against dicotyledonous plants
(Brassica campestris L) at the concentration of 100 mg/L. For example, compound 5i possessed 92.0%
inhibitory activity against B. campestris L and showed better activity than that of the commercialized
herbicide Bispyribac-sodium; however, compounds 5 displayed weak herbicidal activity at the concen-
tration of 10 mg/L.
J. Heterocyclic Chem., 47, 162 (2010).
INTRODUCTION
thetic route is listed in Scheme 1, the molecular struc-
ture of compound 5b is shown in Figure 2. Crystallo-
graphic data (excluding structure factors) for the struc-
ture have been deposited with the Cambridge Crystallo-
graphic Data Center as supplementary publication
CCDC No. 734888 (available free of charge at http://
www.ccdc.cam.ac.uk/conts/retrieving/html or from the
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK).
a-Amino phosphonic acid and their ester derivatives,
as bioisosteres of natural amino acids, are receiving an
increasing attention in medicinal chemistry and pesticide
science due to their wide biological activities, such as
enzyme inhibition, antibiotics, and haptens of catalytic
antibodies, fungicides, herbicides, plant regulators and
plant virucides [1–7]. Recently, 1,2,4-Triazolopyrimidine
derivatives exhibited wide biological activities and were
used as herbicides in plant protection [8–12]. A lot of
triazolopyrimidine sulfonamide herbicides, such as Clor-
ansulam-methyl, Flumetsulam, Diclosulam, Penoxsulam
and Metosulam (Fig. 1), were commercialized, these
herbicides acted as acetolactate synthase (ALS) inhibi-
tors, which have been identified as a very fruitful acting
target for herbicides in the last decades [13]. To find
novel potent and selective herbicide lead compounds,
we have designed a series of novel 1,2,4-triazolo[1, 5-
a]pyrimidine derivatives containing an a-amino phos-
phonate moiety 5. The target compounds 5 were eval-
uated for herbicidal activities in this paper. The syn-
RESULTS AND DISCUSSION
Synthesis and structure determination of title com-
pounds 5. 5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-
2-methylsulfone 1 were prepared using 3-amino-1,2,4-
triazole-5-thiol and acetyl acetone as the starting materi-
als, followed by S-alkylation and oxidation by H2O2
and NaWO4 in good yield. 2-(5,7-Dimethyl-[1,2,4]
triazolo[1,5-a]pyrimidin-2-yloxy)benzoic acid 3 was pre-
pared by the reaction of 1 and methyl 2-hydroxyben-
zoate in the presence of sodium hydroxide in refluxing
toluene, followed by the saponification in the presence
C
V
2010 HeteroCorporation

January 2010 Synthesis and Herbicidal Activity of O,O-Dialkyl N-[2-(5,7-dimethyl-[1,2,4]triazolo-
[1,5-a]pyrimidin-2-yloxy)benzoxyl]-1-amino-1-substitutedbenzyl Phosphonates
163
Figure 1. Structures of some commercial triazolopyrimidine-2-sulfonamide herbicides.
of aqueous sodium hydroxide. 3 reacted with a-amino-
phosphonates 4 to generate the target compounds 5 in
good yields in mild condition using dicyclohexylcarbo-
diimide (DCC) as the dehydration agent. The structures
of target compounds 5 were characterized from their
the experimental section. The results of preliminary bio-
assy indicated that some of the title compounds 5 pos-
sessed moderate herbicidal activities against dicotyledo-
nous plants (B. campestris L) at the concentration of 100
mg/L. For example, compound 5i possessed 92.0% inhib-
itory activity against B. campestris L and showed better
herbicidal activity than that of the commercialized herbi-
cide Bispyribac-sodium. Futhermore, most of compounds
5 showed stronger inhibitory activity against dicotyledo-
nous plants (B. campestris L) than that of monocotyledo-
nous plants (Radix E. crus-galli). However, compounds 5
displayed weak herbicidal activity at the concentration of
10 mg/L. Further herbicidal evaluation (in vivo) and the
structure–activity relationships are under investigation.
Conclusion. In summary, we have designed and syn-
thesized one series of novel 1,2,4-triazolo[1,5-a]pyrimi-
dine derivatives containing an a-amino phosphonate
moiety 5. The results of preliminary bioassy indicated
that some of the title compounds 5 possessed moderate
herbicidal activities against dicotyledonous plants (B.
campestris L) at the concerntration of 100 mg/L.
1
spectral data (IR, H NMR, 31P NMR, EI-MS) and ele-
mental analysis, compound 5b was further determined by
single crystal X-ray diffraction analysis (see Fig. 2). In
1
the H NMR spectra of 5, the CH proton linking with the
phosphonyl group displayed doublet of doublet due to
coupling with P atom and NH proton with the coupling
constant of 21 and 9.0 Hz, respectively. While the NH
and pyrimidine protons appeared as a singlet with chemi-
cal shift atd 6.8 and 8.0, respectively. The IR spectra of
compounds 5 showed normal stretching absorption bands
indicating the existence of the NH (ꢀ3240 cmꢁ1), C¼¼O
(ꢀ1660 cmꢁ1), P¼¼O (ꢀ1225 cmꢁ1), PAOAC (ꢀ1025
cmꢁ1) moieties. The ESI-MS of compounds 5 revealed
the existence of their molecular ion peaks, which were in
accordance with the given structures of products 5.
Herbicidal activities. The herbicidal activity values
of the title compounds 5 against Brassica campestris L
(rape) and Echinochloa crus-galli (barnyard grass) has
been investigated at the dosages of 100 and 10 mg/L
compared with the commercially available herbicide,
Bispyribac-sodium according to the method described in
EXPERIMENTAL
The melting points of the products were determined on an
XT-4 binocular microscope (Beijing Tech Instrument, Beijing,
Scheme 1. Synthesis of the title compounds 5.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

164
W. Tang and D.-Q. Shi
Vol 47
Figure 2. Molecular structure of compound 5b. [Color figure can be viewed in the online issue, which is available at www.interscience.
wiley.com.]
China) and were uncorrected. The IR spectra were recorded on
a Nicolet NEXUS470 spectrometer as KBr pellets with absorp-
.
tion given in cmꢁ1 1H and 31P NMR spectra were performed
silica gel using petroleum ether/acetone (1:1 v/v) as the eluent,
giving a white solid, yield: 68%, mp: 141–142ꢂC. Anal. Cacld
for C15H14N3O3: C, 60.40; H, 4.73; N, 18.78. Found: C,
60.17; H, 4.91; N, 18.55.
on a Varian Mercury-PLUS400 (400 MHz) or Varian Mercury
Plus-600 (600 MHz) spectrometer at room temperature in
CDCl3 with TMS and 85% H3PO4 as the internal and external
standards, respectively. Mass spectra was measured on an
Applied Biosystems API 2000 LC/MS/MS (ESI-MS) spectro-
meter. Elemental analysis was taken on a Elementar Vario EL
III elemental analysis instrument. X-ray diffraction was carried
out on a Bruker Smart 1000 CCD diffractometer (Germany).
Analytical thin layer chromatography (TLC) was performed on
silica gel GF254. Column chromatographic purification was car-
ried out using silica gel. Unless otherwise noted, all materials
were commercially available and were used directly without fur-
ther purification. All solvents were dried and redistilled before
use. 5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-methylsulfone
1 were prepared by the annulation reaction of 3-amino-1,2,4-tri-
azole-5-thiol with acetyl acetone, followed by S-alkylation and
oxidation by H2O2 and NaWO4 according to the reported proce-
dure [14], yield 82%, m.p. 187–188ꢂC. Dialkyl a-amino phos-
phonates 4 were prepared from aromatic aldehyde, ammonium
hydroxide and dialkyl phosphites in moderate yields according
to the reported synthetic protocols [15,16].
Synthesis of methyl 2-(5,7-dimethyl-[1,2,4]triazolo[1,5-
a]pyrimidin-2-yloxy)benzoate 2. Methyl 2-hydroxy-benzoate
(0.91 g, 6 mmol), sodium hydroxide (0.24 g, 6 mmol) and
anhydrous toluene (60 mL) were stirred under reflux for 3h,
while the water was removed away during the reaction time.
5,7-Dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-methylsulfone 1
(2.26 g, 10 mmol) was added and stirred under reflux for 10 h
till the reaction completed (monitored by TLC). The solid was
filtered off, and the solvent was removed under a reduced pres-
sure, the residue was purified by column chromatography on
Synthesis of 2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimi-
din-2-yloxy)benzoic acid 3. Methyl 2-(5,7-dimethyl-[1,2,4]tri-
azolo[1,5-a]pyrimidin-2-loxy)benzoate 2 (1.19 g, 4 mmol), so-
dium hydroxide (0.32 g, 8 mmol), water (10 mL) and ethanol
(10 mL) were stirred at 80–90ꢂC for 1–2 h. The solution was
acidified by dilute hydrochloride, The crude product was col-
lected by filtration, washed by ethyl ether, the product was
obtained as a yellow solid, yield: 80%, mp: 103–104ꢂC. Anal.
Cacld for C14H12N4O3: C, 59.15; H, 4.25; N, 19.71. Found: C,
59.30; H, 4.19; N, 19.47.
General synthetic procedure for O,O-dialkyl N-[2-(5,7-di-
methyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yloxy)benzoxyl]-1-
amino-1-substitutedbenzyl
phosphonate
5. 2-(5,7-di-
methyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yloxy)benzoic acid 3
(0.284 g, 1.0 mmol), O,O0-diethyl a-amino (substituted phenyl)
methylphosphonate 4 (1.0 mmol) and anhydrous chloroform (5
mL) were added to a 50 mL three-necked flask at 273 K, DCC
(0.225 g, 1.1 mmol) in anhydrous chloroform (5 mL) was
added dropwise slowly. The mixture was allowed to be stirred
at room temperature overnight. After the solvent was removed
under a reduced pressure, the residue was purified by column
chromatography on silica gel using petroleum ether/acetone
(1:2 v/v) as the eluent, giving the target compounds as a light
yellow solid or liquid.
O,O-Diethyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyri-
midin-2-yloxy)benzoxyl]-1-amino-1-(p-tolyl) methyl phos-
phonate (5a). Yellow oil, yield 68%; IR (KBr): t 3230
(NAH), 2985 (Ph-H), 1652 (C¼¼O), 1562, 1465, 1426 (Ph),
1248 (P¼¼O), 1025 (PAOAC) cmꢁ1
;
1H NMR (CDCl3, 600
MHz): d 1.12 (t, J ¼ 7.2 Hz, 3H, CH2CH3), 1.21 (t, J ¼ 7.2
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

January 2010 Synthesis and Herbicidal Activity of O,O-Dialkyl N-[2-(5,7-dimethyl-[1,2,4]triazolo-
[1,5-a]pyrimidin-2-yloxy)benzoxyl]-1-amino-1-substitutedbenzyl Phosphonates
165
Hz, 3H, CH2CH3), 2.26 (s, 3H, CH3), 2.64 (s, 3H, CH3), 2.67
(s, 3H, CH3), 3.83–3.85 (m, 1H, CH2), 3.95–3.97 (m, 1H,
CH2), 4.00–4.04 (m, 2H, CH2), 5.67 (dd, J ¼ 9.6 Hz, J ¼ 20.1
Hz, 1H, PCH), 6.80 (s, 1H, pyrimidine-H), 7.01 (d, J ¼ 7.8
Hz, 2H, ArH), 7.28–7.37 (m, 4H, ArH), 7.49 (t, J ¼ 7.8 Hz,
1H, ArH), 7.99 (d, J ¼ 7.8 Hz, 1H, ArH), 8.09 (s, 1H, NH);
ESI-MS: m/z 562 (Mþ þ K-1, 5%), 546 (Mþ þ Na-1, 23%),
523.7 (Mþ, 100%), 267 (10%). Anal. Cacld for C26H30N5O5P:
C, 59.65; H, 5.78; N, 13.38. Found: C, 59.47; H, 5.51; N,
13.24.
(dd, J ¼ 8.8 Hz, J ¼ 21.0 Hz, 1H, PCH), 6.83 (s, 1H, pyrimi-
dine-H), 7.08 (d, J ¼ 8.0 Hz, 1H, ArH), 7.29–7.39 (m, 3H,
ArH), 7.46–7.53 (m, 2H, ArH), 8.02 (d, J ¼ 8.0 Hz, 1H,
ArH), 8.22 (s, 1H, NH). Anal. Cacld for C25H26Cl2N5O5P: C,
51.91; H, 4.53; N, 12.11. Found: C, 52.13; H, 4.27; N, 12.04.
O,O-Diethyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyri-
midin-2-yloxy)benzoxyl]-1-amino-1-(4-bromophenyl) methyl
phosphonate (5f). Yellow solid, m.p. 119–120ꢂC, yield 88%;
IR (KBr): t 3235 (NAH), 2992 (Ph-H), 1672 (C¼¼O), 1556,
1459, 1430 (Ph), 1245 (P¼¼O), 1026 (PAOAC) cmꢁ1
;
1H
O,O-Diethyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyri-
midin-2-yloxy)benzoxyl]-1-amino-1-phenylmethyl phospho-
nate (5b). Yellow solid, m.p. 136–137ꢂC, yield 69%; IR
(KBr): t 3238 (NAH), 2982 (Ph-H), 1658 (C¼¼O), 1558, 1463,
NMR (CDCl3, 400 MHz): d 1.15 (t, J ¼ 7.2 Hz, 3H,
CH2CH3), 1.24 (t, J ¼ 7.2 Hz, 3H, CH2CH3), 2.66 (s, 6H,
2CH3), 3.90–4.06 (m, 4H, 2CH2), 5.65 (dd, J ¼ 9.2 Hz, J ¼
20.6 Hz, 1H, PCH), 6.83 (s, 1H, pyrimidine-H), 7.29–7.38 (m,
4H, ArH), 7.51 (t, J ¼ 7.6 Hz, 1H, ArH), 7.98 (d, J ¼ 8.0 Hz,
1H, ArH), 8.10 (s, 1H, NH). Anal. Cacld for C25H27BrN5O5P:
C, 51.03; H, 4.63; N, 11.90. Found: C, 51.34; H, 4.90; N,
11.73.
O,O-Diethyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyri-
midin-2-yloxy)benzoxyl]-1-amino-1-(2-chlorophenyl) methyl
phosphonate (5g). white solid, m.p. 144–145ꢂC, yield 68%;
IR (KBr): t 3417, 3236 (NAH), 2990 (Ph-H), 1665(C¼¼O),
1
1420 (Ph), 1252 (P¼O), 1026 (PAOAC) cm-1; H NMR (400
MHz, CDCl3): d 1.12 (t, J ¼ 7.2 Hz, 3H, CH2CH3), 1.21 (t, J
¼ 7.2 Hz, 3H, CH2CH3), 2.65 (s, 3H, CH3), 2.69 (s, 3H,
CH3), 3.81–3.87 (m, 1H, CH2), 3.93–4.05 (m, 3H, 2CH2), 5.71
(dd, J ¼ 9.6 Hz, J ¼ 20.6 Hz, 1H, PCH), 6.81 (s, 1H, pyrimi-
dine-H), 7.18–7.25 (m, 3H, ArH), 7.27–7.43 (m, 4H, ArH),
7.50 (t, J ¼ 8.0 Hz, 1H, ArH), 8.01 (d, J ¼ 7.6 Hz, 1H, ArH),
8.15 (dd, J ¼ 4.0 Hz, J ¼ 9.0 Hz, 1H, NH); 31P NMR
(CDCl3, 162 MHz): d 19.58; ESI-MS: m/z 547 (Mþ þ K-1,
5%), 531.5 (Mþ þ Na-1, 14%), 509.1 (Mþ, 100%), 266.6
(5%). Anal. Cacld for C25H28N5O5P: C, 58.93; H, 5.54; N,
13.75. Found: C, 59.12; H, 5.68; N, 13.51.
1626, 1557, 1479 (Ph), 1233 (P¼¼O), 1025 (PAOAC) cmꢁ1
;
1H NMR (CDCl3, 600 MHz): d 1.10 (t, J ¼ 7.2 Hz, 3H,
CH2CH3), 1.26 (t, J ¼ 7.2 Hz, 3H, CH2CH3), 2.65 (s, 3H,
CH3), 270 (s, 3H, CH3), 3.80–3.82 (m, 1H, CH2), 3.92–3.95
(m, 1H, CH2), 4.11–4.14 (m, 2H, CH2), 6.26 (dd, J ¼9.0 Hz, J
¼ 20.7 Hz, 1H, PCH), 6.81 (s, 1H, pyrimidine-H), 7.10–7.14
(m, 2H, ArH), 7.32 (d, J ¼ 10.2 Hz, 2H, ArH), 7.37 (d, J ¼
7.8 Hz, 1H, ArH), 7.49 (d, J ¼ 7.8 Hz, 1H, ArH), 7.53 (d, J
¼ 7.2 Hz, 1H, ArH), 8.02 (d, J ¼ 8.4 Hz, 1H, ArH), 8.27 (s,
1H, NH); 31P NMR (CDCl3, 243 MHz): d 18.89; ESI-MS: m/z
581.6 (Mþ þ K-1, 3%), 563.8 (Mþ þ Na-1, 7%), 543.4 (Mþ,
100%), 266.8 (2%). Anal. Cacld for C25H27ClN5O5P: C,
55.20; H, 5.00; N, 12.88. Found: C, 54.97; H, 4.73; N, 12.60.
O,O-Diethyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyri-
midin-2-yloxy)benzoxyl]-1-amino-1-(4-fluorophenyl) methyl
phosphonate (5h). Yellow solid, m.p. 147–148ꢂC, yield 73%;
IR (KBr): t 3241 (NAH), 2995 (Ph-H), 1662 (C¼¼O), 1622,
O,O-Diethyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyri-
midin-2-yloxy)benzoxyl]-1-amino-1-(4-chlorophenyl) methyl
phosphonate (5c). yellow solid, m.p. 121–123ꢂC, yield 75%;
IR (KBr): t 3228 (NAH), 2987 (Ph-H), 1663 (C¼¼O), 1561,
1468, 1418 (Ph), 1246 (P¼¼O), 1019 (PAO¼¼C) cmꢁ1
;
1H
NMR (CDCl3, 400 MHz): d 1.15 (t, J ¼ 7.2 Hz, 3H,
CH2CH3), 1.23 (t, J ¼ 7.2 Hz, 3H, CH2CH3), 2.66 (s, 6H,
CH3), 3.88–4.07 (m, 4H, 2CH2), 5.68 (dd, J ¼ 8.0 Hz, J ¼
20.8 Hz, 1H, PCH), 6.83 (s, 1H, pyrimidine-H), 7.15 (d, J ¼
8.0 Hz, 2H, ArH), 7.34–7.38 (m, 4H, ArH), 7.52 (t, J ¼ 6.8
Hz, 1H, ArH), 8.00 (d, J ¼ 8.0 Hz, 1H, ArH), 8.07 (s, 1H,
NH); ESI-MS: m/z 565.8 (Mþ þ Na-1, 17%), 543.8 (Mþ,
100%), 266.9 (12%). Anal. Cacld for C25H27ClN5O5P: C,
55.20; H, 5.00; N, 12.88. Found: C, 55.03; H, 4.87; N, 12.95.
O,O-Diethyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimi-
din-2-yloxy)benzoxyl]-1-amino-1-(4-methoxyphenyl) methyl
phosphonate (5d). Yellow solid, m.p. 89–90ꢂC, yield 67%; IR
(KBr): t 3236 (NAH), 2992 (Ph-H), 1661 (C¼¼O), 1564, 1466,
1554, 1485 (Ph), 1230 (P¼¼O), 1021 (PAOAC) cmꢁ1
;
1H
NMR (CDCl3, 600 MHz): d 1.14 (t, J ¼ 7.2 Hz, 3H,
CH2CH3), 1.22 (t, J ¼ 7.2 Hz, 3H, CH2CH3), 2.65 (s, 3H,
CH3), 2.67 (s, 3H, CH3), 3.87–3.90 (m, 1H, CH2), 3.96–3.99
(m, 1H, CH2), 4.00–4.06 (m, 2H, CH2), 5.68 (dd, J ¼ 9.0 Hz,
J ¼ 20.4 Hz, 1H, PCH), 6.81 (s, 1H, pyrimidine-H), 6.88 (t, J
¼ 9.0 Hz, 2H, ArH), 7.33–7.42 (m, 4H, ArH), 7.51 (t, J ¼ 7.2
Hz, 1H, ArH), 8.00 (d, J ¼ 8.4 Hz, 1H, ArH), 8.08 (s, 1H,
NH). Anal. Cacld for C25H27FN5O5P: C, 56.92; H, 5.16; N,
13.28. Found: C, 57.12; H, 5.27; N, 13.65.
1425 (Ph), 1242 (P¼¼O), 1025 (PAOAC) cmꢁ1
;
1H NMR
(CDCl3, 400 MHz): d 1.12 (t, J ¼ 7.2 Hz, 3H, CH2CH3), 1.24
(t, J ¼ 7.2 Hz, 3H, CH2CH3), 2.67 (s, 3H, CH3), 2.68 (s, 3H,
CH3), 3.84 (s, 3H, OCH3), 3.86–4.05 (m, 4H, 2CH2), 5.68 (dd,
J ¼ 9.4 Hz, J ¼ 20.8 Hz, 1H, PCH), 6.83 (s, 1H, pyrimidine-
H), 7.01 (d, J ¼ 8.8 Hz, 2H, ArH), 7.27–7.37 (m, 4H, ArH),
7.51 (d, J ¼ 7.6 Hz, 1H, ArH), 7.98 (d, J ¼ 9.6 Hz, 1H,
ArH), 8.10 (s, 1H, NH). Anal. Cacld for C26H30N5O6P: C,
57.88; H, 5.60; N, 12.98. Found: C, 58.05; H, 5.85; N, 12.81.
O,O-Diethyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimi-
din-2-yloxy)benzoxyl]-1-amino-1-(2,4-dichlorophenyl) methyl
phosphonate (5e). Yellow solid, m.p. 96–97ꢂC, yield 85%; IR
(KBr): t 3232 (NAH), 2996 (Ph-H), 1668 (C¼¼O), 1560, 1461,
O,O-Dibutyl N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyri-
midin-2-yloxy)benzoxyl]-1-amino-1-(phenyl) methyl phos-
phonate (5i). Yellow oil, yield 52%; IR (KBr): t 3236
(NAH), 2998 (Ph-H), 1654 (C¼¼O), 1618, 1550, 1482 (Ph),
1225 (P¼¼O), 1025 (PAOAC) cmꢁ1
;
1H NMR (CDCl3, 600
MHz) d: 0.79 (t, J ¼ 7.8 Hz, 3H, CH2CH3), 0.83 (t, J ¼ 7.2
Hz, 3H, CH2CH3), 1.20–1.53 (m, 8H, 2CH2CH2), 2.68 (s, 3H,
CH3), 2.70 (s, 3H, CH3), 3.72–3.75 (m, 1H, CH2), 3.87–3.90
(m, 1H, CH2), 3.93–3.99 (m, 2H, CH2), 5.72 (dd, J ¼ 9.0 Hz,
J ¼ 20.4 Hz, 1H, PCH), 6.80 (s, 1H, pyrimidine-H), 7.17–7.22
(m, 3H, ArH), 7.33 (t, J ¼ 7.2 Hz, 1H, ArH), 7.35 (d, J ¼ 8.0
Hz, 1H, ArH), 7.42 (d, J ¼ 7.2 Hz, 2H, ArH), 7.49 (t, J ¼ 7.2
1432 (Ph), 1246 (P¼¼O), 1028 (PAOAC) cmꢁ1
;
1H NMR
(CDCl3, 400 MHz): d 1.13 (t, J ¼ 8.0 Hz, 3H, CH2CH3), 1.29
(t, J ¼ 8.0 Hz, 3H, CH2CH3), 2.66 (s, 3H, CH3), 2.68 (s, 3H,
CH3), 3.86–3.99 (m, 2H, CH2), 4.11–4.15 (m, 2H, CH2), 6.18
Journal of Heterocyclic Chemistry
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W. Tang and D.-Q. Shi
Vol 47
Table 1
Inhibition of the seedling growth of barnyard grass
[Radix Echinochloa crus-galli]. Ten Radix 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 germi-
nate for 72 h at 28 6 1ꢂC. The heights of the above-ground
parts of the seedlings in each cup were measured, and the
mean values were calculated. The percentage inhibition was
used to describe the control efficiency of the compounds. The
herbicidal activity is also listed in Table 1.
The herbicidal activities of compounds 5a–5i (in vitro, relative
inhibitory rate %, concentration, mg/L).
Brassica
campestris
root test
Echinochloa
crusgalli cup
test
Compounds
100
10
100
10
5a
5b
5c
5d
5e
5f
5g
42.9
52.1
39.7
29.0
45.3
33.6
34.1
7.0
15.4
26.6
0
25.9
30.5
29.5
19.5
15.1
14.6
11.6
20.0
23.4
72.4
13.1
21.0
0
19.2
14.0
4.7
0
11.7
9.0
0
Acknowledgments. The authors are grateful to the Natural Sci-
ence Foundation of China (Grant No. 20872046), and the Natural
Science Foundation of Hubei Province (Grant No. 2008CDB086)
for the financial support.
6.2
6.2
7.6
46.9
5h
5i
Bispyribac-sodium
0
92.0
69.8
31.3
65.6
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet