An efficient synthesis of 2-(2,2-difluoroethoxy)-6-trifluoromethyl-n-(5,8- dimethoxy-1,2,4-triazolo[1,5-c]pyrimidine-2-yl) benzenesulfonamide: Penoxsulam

Article abstract of DOI:10.3184/174751913X13619014318618

An efficient nine-step synthesis of 2-(2,2-difluoroethoxy)-6- trifluoromethyl-N-(5,8-dimethoxy-1,2,4-triazolo[1,5-c] - pyrimidine-2-yl) benzenesulfonamide has been developed. The starting material 4-nitro-2-(trifluoromethyl)aniline starting material was converted via 2-bromo-4-amino-6-trifluoromethylaniline and 2-bromo-4-acetamido-6- trifluoromethylbenzenesulfonic acid to 2-bromo-6-trilfuoromethylbenzenesulfonic acid. This was then combined with 2-amino-5,8-dimethoxy-1,2,4-triazolo[1.5-c] pyrimidine to give the target molecule. Compared with the reported method, this approach has advantages in its shorter reaction time, milder reaction conditions and easier purifiction. Moreover, the overall yield has been improved to 22.9% which is twice of that of the reported method.

Full text of DOI:10.3184/174751913X13619014318618

JOURNAL OF CHEMICAL RESEARCH 2013
RESEARCH PAPER 197
APRIL, 197–200
An efficient synthesis of 2-(2,2-difluoroethoxy)-6-trifluoromethyl-n-
(5,8-dimethoxy-1,2,4-triazolo[1,5-c]pyrimidine-2-yl) benzenesulfonamide:
penoxsulam
Feifei Wu, Shiguang Gao, Zhiyin Chen, Jinyue Su and Dayong Zhang*
Drug Research Institute, China Pharmaceutical University, 24 RoadTongjia Xiang, Nanjing 210009, P. R. China
An efficient nine-step synthesis of 2-(2,2-difluoroethoxy)-6-trifluoromethyl-N-(5,8-dimethoxy-1,2,4-triazolo[1,5-c]-
pyrimidine-2-yl) benzenesulfonamide has been developed. The starting material 4-nitro-2-(trifluoromethyl)aniline
starting material was converted via 2-bromo-4-amino-6-trifluoromethylaniline and 2-bromo-4-acetamido-6-trifluoro-
methylbenzenesulfonic acid to 2-bromo-6-trilfuoromethylbenzenesulfonic acid. This was then combined with
2-amino-5,8-dimethoxy-1,2,4-triazolo[1.5-c]pyrimidine to give the target molecule. Compared with the reported
method, this approach has advantages in its shorter reaction time, milder reaction conditions and easier purifiction.
Moreover, the overall yield has been improved to 22.9% which is twice of that of the reported method.
Keywords: triazolo[1,5-c]pyrimidine benzenesulfonamide, 4-nitro-2-(trifluoromethyl)aniline, benzenesulfonyl chloride, penox-
sulam
2-(2,2-Difluoroethoxy)-6-trifluoromethyl-N-(5,8-dimethoxy-
1,2,4-triazolo[1,5-c]pyrimidine-2-yl) benzenesulfonamide,
In the original method, a halogen-metal exchange reaction,
dimethoxymethyl reaction and etherification took more than
20 hours. Two of the procedures referred above needed the
protection of inert nitrogen gas. The reagent 1,2-dipropyl-
disulfane discouraged us due to its terrible odour. Moreover,
all of the work ups used vacuum distillation to purify the oily
intermediates except compound 3. In short, this is not an
attractive method because of the very long reaction times,
harsh reaction conditions and complicated work-up. The major
problem was the rather low yield (24%) of the coupling reaction
to form penoxsulam from compound 2 and 3, reducing the
overall yield of the reported method to 11.0%.
penoxsulam (1), is a novel and effective herbicide developed
by Dow AgroSciences in 1999 with the brand name Granite.1
As a member of the triazolo[1,5-c]pyrimidine sulfonamides
class of herbicides, it has been demonstrated competition with
the amino acid leucine for binding to acetolactate synthase
(ALS) isolated from cotton (Gossypium hirsutum).2 It exhibits
higher levels of activity on both grass and broadleaf weeds
than other commercial triazolopyrimidine sulfonamides,3
such as the triazolo[1,5-a]pyrimidine sulfonamides. It is used
primarily in rice because of its broad weed control spectrum
and safety to rice in effective dose.4,5
Most of the research on penoxsulam has been focused on
the partitioning,6 analysis,7 degradation such as photodegrada-
tion,8 and microbial degradation9 in water or soil, mechanism
of resistance,10 effect on weeds and safety evaluation.11 The
synthesis and structure-activity of the triazolopyrimidine
sulfonamides has also been extensively studied during the past
decade.3
Although there are several methods for the synthesis of
triazolo[1,5-c]pyrimidine sulfonamides, such as coupling route
and derivative route, it has been reported3 that penoxsulam
could be prepared via the coupling of 2-amino-5,8-dimethoxy-
1,2,4-triazolo[1,5-c]pyrimidine (2) with 2-trifluoromethyl-6-
difluoroethoxybenzenesulfonyl chloride (3) (Scheme 1).
Methods for the synthesis of compound 2 have been reported
in several papers.12–15 One common high yielding route16 which
used 2-substituted-4-amino-5-methoxypyrimidine as the start-
ing material and did not use hydrazine and cyanogen halide
was reported by Dow Agrosciences LLC. In this paper,
compound 2 was prepared by Edmonds’s method.15 However,
compound 3 has been prepared by a method from the starting
material 1-(methoxymethoxy)-3-(trifluoromethyl) benzene.2
In order to overcome these problems, we examined a more
efficient method for the synthesis of penoxsulam.
Results and discussion
In the light of the steric hindrance blockade of the difluoro-
ethoxyl group in compound 3, we put the etherification reaction
with 2,2-difluoroethanol after the general coupling reaction.
We designed an efficient method for the synthesis of penoxsulam
basedontheliterature17 whichused4-nitro-2-(trifluoromethyl)-
aniline (compound 4) as the starting material (Scheme 2).
The synthesis of penoxsulam involved bromination, reduc-
tion, acetylation, diazotisation, deacetylation, acid hydrolysis,
chlorination, coupling and etherification. Compound 4 was
reacted with hydrogen bromide and hydrogen peroxide to give
5. Reduction of 5 in the presence of stannous chloride in etha-
nol afforded 6. This was followed by acetylation of the amino
group to give 7. With the amino group protected, compound 7
was diazotised and deacetylated. In the presence of the
base sodium ethoxide and t-butyl nitrite, the amino group of
compound 9 was replaced by hydrogen. Compound 11 was
synthesised by chlorination of compound 10 in the presence
phosphorus oxychloride and acetonitrile under reflux and then
Scheme 1 The coupling reaction for the synthesis of penoxsulam.
* Correspondent. E-mail: zhangdayong@cpu.edu.cn

198 JOURNAL OF CHEMICAL RESEARCH 2013
reacted with 2 to give compound 12 with a high yield in
the presence of the catalyst sulfilimine. The target product 1
was formed by etherification. This step was improved by
substantial research.
proceeded under acidic conditions and the best result was
obtained at 0 °C. The conversion of 9 to 10 proceeded under
basic conditions and the best result was obtained at 55 °C.
In order to decrease the steric hindrance the condensation
of 11 with 2 was accomplished successfully with a yield of
up to 92.7% and this was followed by the etherification of 12
to get 1.
This method shortened the reaction time to less than 8 hours
and improved the efficiency considerably. The conditions were
mild and the reagents that were used were inexpensive.
Moreover most of the intermediates were isolated by filtration
without recourse to column chromatography, making the post-
processing more convenient. Finally the overall yield improved
to 22.9% which is twice of that of the reported process
(11.0%).
In order to optimise the route, the next step was to find the
best parameters for each stage. Hydrogen bromide together
with hydrogen peroxide and bromine alone were used as
reagents for the bromination reaction. Considering the volatil-
ity and poisonous nature of bromine, we chose hydrogen
bromide and hydrogen peroxide as the bromination reagent.
In this reaction, the temperature was the key parameter. The
golden yellow substrate did not dissolve well in the polar
solvent below 50 °C. When the temperature reached 80 °C,
there would be a danger due to the presence of hydrogen per-
oxide. A better result was obtained at 60–70 °C. In the second
reduction step, different reducing agents, such as stannous
chloride in ethanol, iron in acetic acid and zinc dust in acetic
acid were screened at 78–80 °C. The results showed that
the optimum yield was obtained in the presence of stannous
chloride. The metal reducing agents made the postprocessing
difficult and product 6 was impure due to the unreacted metals
and less compound 7 was formed in the next step. The
remaining steps could be easily accomplished in our hands and
are not discussed in detail. The diazotisation was a classical
reaction in organic synthesis in which the temperature was
the key parameter. The transformation of compound 7 to 8
Conclusion
An efficient synthesis of 2-(2,2-difluoroethoxy)-6-trifluoro-
methyl-N-(5,8-dimethoxy-1,2,4-triazolo[1,5-c]pyrimidine-2-yl)
benzenesulfonamide has been developed which used 4-nitro-
2-(trifluoromethyl)aniline as the starting material. Compared
with the reported method, this approach has advantages in its
shorter reaction time, milder reaction conditions, and easier
work-up. Moreover, the overall yield has been improved to
22.9% which is twice of that of the reported method.
Scheme 2 An efficient synthesis of penoxsulam (overall yield 22.9%).

JOURNAL OF CHEMICAL RESEARCH 2013 199
(60 mL) in an ice bath. Then the resulting suspension was stirred for
2.5 h at 0–5 °C. The precipitated product was filtered, washed with
water (200 mL) and dried in a vacuum oven at 50 °C to afford 8 as
an off-white solid. Yield: 34.2 g (88.9%). m.p. 182–184 °C. 1H NMR
(DMSO-d6, 300 MHz): δ 2.07 (s, 3H, CH3), 7.9 (d, 1H, J = 1.7 Hz, Ar
H), 8.11 (d, 1H, J = 1.7 Hz, Ar H), 10.41 (s, 1H, NH), 12.20 (br s, 1H,
SO3H). IR (KBr), v/cm−1: 3445, 3316, 3253, 3173, 3091, 1683, 1584,
1524, 1392, 1304, 1193, 1157, 882, 696. ESI-MS m/z: 360.1 [base
peak, M-1]. HRMS: calcd for C9H7BrF3NO4S [M-H]− 359.9153, found
359.9156.
Experimental
Reagents and solvents were obtained from commercial suppliers and
used without purification.Column chromatography was conducted on
silica gel (100–200 mesh) from Qingdao Ocean Chemical Factory.
2-Amino-5,8-dimethoxy-1,2,4-triazolo[1,5-c]pyrimidine (compound
2) was prepared by Edmonds’s method.15 Melting points were recorded
1
on a XT-4 melting point apparatus from Taike, Beijing. H NMR
spectra were obtained in either CDCl3, DMSO-d6 or D2O, used as
purchased, and were recorded on a Bruker 300 MHz, and referenced
to an internal standard of tetramethylsilane (TMS 1H: δ 0.00). 1H–1H
couplings are assumed to be first order and peak multiplicity is
reported as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet),
or br (broad). Mass spectroscopic data were obtained on a Bruker
Esruire 3000 Plus series chromatograph (ESI). IR spectra were
measured using a ThermoFisher Nicolet 470 FT-IR spectrometer.
High-resolution mass spectrometry (HRMS) was performed using a
Waters Micromass LCT Premier spectrometer. Reactions were moni-
tored by thin layer chromatography (TLC) on GF254 silica gel plates
and visualised with ZF-20D ultraviolet analytic apparatus.
2-Bromo-4-amino-6-trifluoromethybenzenesulfonic acid (9): A round
bottomed flask (250 mL) fitted with an additional funnel and mechan-
ical stirrer was charged with compound 8 (28.0 g, 0.074 mol), 37%
hydrochloric (20 mL) and ethanol (100 mL). The resulting mixture
was heated under reflux for 2 h, and then cooled to room temperature.
The solvent was removed in vacuum. The residue was filtered, washed
with ethanol (10 mL) and dried in a vacuum oven at 50 °C to afford 9
1
as a white solid. Yield: 22.2 g (94.3%). m.p. >250 °C. H NMR
(DMSO-d6, 300 MHz): δ 7.02 (s, 1H, Ar H), 7.15 (s, 1H, Ar H), 7.64
(br s, 3H, NH2, SO3H). IR (KBr), v/cm−1: 3433, 3097, 3021, 2676,
1608,1561, 1509, 1298, 1234, 1161, 1115, 1076, 877, 700, 676. ESI-
MS m/z: 317.9 [base peak, M-1]. HRMS: calcd for C7H5BrF3NO3S
[M-H]− 317.9047, found 317.9050.
2-Bromo-4-nitro-6-trifluoromethylaniline (5): Compound 4 (67.9 g,
0.329 mol) and 40% hydrogen bromide (73.1 g, 0.36l mol) were
placed in a round bottomed flask (500 mL) at room temperature. The
resultant reaction mixture was stirred for 10 min and then heated to
60–70 °C. 30% hydrogen peroxide (40.5 g, 0.357 mol) diluted with
water (40 mL) was added slowly to the resultant suspension for 1 h
and the reaction mixture was stirred for 2 h at 60–70 °C. The precipi-
tated solid was filtered off with suction, washed with water (800 mL)
and dried at 60 °C to afford 5 as yellow powder.Yield: 93.2 g (99.2%).
The spectroscopic data of the yellow solid was in accordance with
the reported values.14 m.p. 136–128 °C (lit.14 138–140 °C).1H NMR
(CDC13, 300 MHz): δ 5.44 (br s, 2H, NH2), 8.38 (d, 1H, J = 2.4 Hz,
Ar H-5), 8.52 (d, 1H, J = 2.7 Hz, Ar H-3). IR (KBr), v/cm−1: 3494,
3388, 3200, 1623, 1516, 1482, 1315, 1122, 917, 743, 708, 686.
2-Bromo-4-amino-6-trifluoromethylaniline (6): Stannous chloride
(27.1 g, 0.120 mol) was added to a suspension of 5 (11.4 g, 0.04 mol)
and ethanol (80 mL), and the resultant reaction mixture was heated to
reflux for 3 h. The ethanol was completely distilled off below 55 °C
under reduced pressure and the residue was made alkaline to pH =
11–12 with 20% aqueous sodium hydroxide solution (300 mL). Then
ethyl acetate (200 mL) was introduced and stirred for 30 min. The
unwanted solid was filtered and washed with ethyl acetate (50 mL).
The resultant filtrate was poured into a tap funnel and the organic
solution was washed with water (200 mL×2), and dried with anhy-
drous sodium sulfate (10 g). The solvent was removed under reduced
pressure to afford 6 as a tan solid. Yield: 10.0 g (97.1%). m.p. 45–
47 °C. 1H NMR (CDCl3, 300 MHz): δ 3.34 (br s, 2H, NH2), 4.19 (br s,
2H, NH2), 6.80 (d, 1H, J = 2.4 Hz, Ar H), 7.02 (d, 1H, J = 2.4 Hz, Ar
H). IR (KBr), v/cm−1: 3483, 3445, 3391, 3364, 3297, 3197, 1620,
1485, 1231, 1111, 936, 872, 697. HRMS: calcd for C7H6BrF3N2
[M-H]− 252.9588, found 252.9590.
2-Bromo-6-trifluoromethybenzenesulfonic acid (10):
A round
bottomed flask (250 mL) fitted with a thermometer and mechanical
stirrer was charged with n-butyl alcohol (37.0 g, 0.50 mol), water
(10 mL) and 98% sulfuric acid (14 mL). The resultant mixture was
stirred and cooled to 0–2 °C. The cold suspension was slowly added
to 20% aqueous sodium nitrite solution (38.0 g, 0.55 mol) for 1 h. The
solution obtained above was transferred to a funnel and the organic
layer was washed with aqueous sodium bicarbonate (200 mL) and
sodium chloride solution (150 mL) and dried with anhydrous sodium
sulfate (10 g). The solvent was evaporated to afford a yellow oil
(36.1 g) of butyl nitrite.
Another round bottomed flask (100 mL) fitted with a thermometer
and mechanical stirrer was charged with 9 (15.9 g, 0.05 mol), sodium
(1.2 g, 0.052 mol) and anhydrous ethanol (50 mL). The resultant reac-
tion mixture was stirred and cooled to 0–2 °C. Butyl nitrite (17.0 g,
0.068 mol) obtained above was added. After the ester was added, the
solution was heated to 60 °C for 3 h. The resulting solution was cooled
to 0 °C, followed by the addition of cuprous chloride (0.8 g, 0.004 mol)
catalyst and concentrated sulfuric acid (15 mL). It was then refluxed
for 2 h. The solution was filtered, extracted with ethyl acetate
(150 mL) and water (100 mL×2), dried with anhydrous sodium sulfate
(10 g) and the solvent was removed to obtained yellow oil. Yield:
10.7 g (70.0%). 1H NMR (CDCl3, 300 MHz): δ 1.99 (s, 1H, SO3H),
7.34–7.40 (t, 1H, J = 7.9 Hz, Ar H-4), 7.75 (d, 1H, J = 7.9 Hz, Ar H-5),
7.92 (d, 1H, J = 7.8 Hz, Ar H-3). IR (KBr), v/cm−1: 3475, 3419, 3167,
2120, 1634, 1401, 1238, 1221, 793, 731, 690, 634, 624. ESI-MS m/z:
302.9 [base peak, M-1]; HRMS calcd for C7H4BrF3O3S [M-1]−
302.8938, found 302.8942.
2-Bromo-4-acetamido-6-trifluoromethylaniline (7): A round bot-
tomed flask (250 mL) fitted with an additional funnel, thermometer
and compound 6 (40.3 g, 0.141 mol) and 1, 2-dichloroethane
(150 mL) was introduced. The resultant reaction mixture was stirred
for 30 min at room temperature, and then acetic anhydride (17.3 g,
0.169 mol) was added slowly. The temperature was maintained at
50 °C for 2 h. The solvent was distilled off below 55 °C under reduced
pressure, and then the residue was filtered, washed with water
(200 mL) and dried in a vacuum oven at 50 °C to afford 7 as a grey
solid. Yield: 45.1 g (96.1%). m.p. 152–154 °C. 1H NMR (DMSO-d6,
300 MHz): δ 2.01 (s, 3H, CH3), 5.21 (br s, 2H, NH2), 7.68 (s, 1H, Ar
H), 7.98 (s, 1H, Ar H), 9.95 (s, 1H, NH). IR (KBr), v/cm−1: 3472,
3358, 3287, 3236, 3174, 3120,1661, 1608, 1551, 1485, 1281, 1111,
877, 703, 695. ESI-MS m/z: 319.0, 321 [base peak, M+23, M+25=
1:1]. HRMS: calcd for C9H8BrF3N2O [M-H]− 294.9694, found
294.9699.
2-Bromo-4-acetamido-6-trifluoromethybenzenesulfonic acid (8):
A round bottomed flask (250 mL) fitted with an additional funnel,
thermometer and mechanical stirrer was charged with compound 7
(30.0 g, 0.101 mol), acetic acid (60 mL), 37% hydrochloric acid
(90 mL) and 98% sulfuric acid (2 mL). The resultant reaction mixture
was stirred for 30 min and cooled to 0–2 °C. 25% Aqueous sodium
nitrite solution (8.5 g, 0.123 mol) was slowly added to the cold solu-
tion at 0–5 °C. The resultant suspension was stirred at this temperature
for 1 h until a completely clear solution was formed. The solution
obtained above was added to a mixture of the catalyst cuprous
chloride (0.2 g, 0.001 mol) and sulfur dioxide dissolved in acetic acid
2-Bromo-6-trifluoromethybenzenesulfonyl chloride (11): 10%
Aqueous potassium hydroxide solution (40 g) was added to compound
10 (15.2 g, 0.05 mol) in methanol at room temperature to generate the
potassium salt of compound 10 (17.1 g, 0.05 mol).
A suspension of this potassium salt of compound 10 (3.4 g, 9.9 mol)
in acetonitrile (8 mL), was treated with tetramethylene sulfone (2.5 g,
21 mol) and phosphorus oxychloride (5.0 g, 32 mmol). The resultant
mixture was stirred and heated to reflux for 1 h. The mixture was then
cooled to room temperature, diluted to ice water (40 mL) and extracted
with dichloromethane (100 mL). The organic layer was washed with
water (100 mL×2), dried with anhydrous sodium sulfate (10 g), fil-
tered and the solvent removed in vacuum to afford the crude product
as tan oil. The oil was purified by column chromatography (SiO2,
0–20%, EtOAc/hexane) to afford 11 as light yellow solid. Yield: 2.6 g
(80.9%). m.p. 40–42 °C. This compound was not stable in the analysis
of 1H NMR spectra and mass spectra, and the sulfonyl chloride group
was easily hydrolysed to sulfonic acid. Its structure could be confirmed
by its easy conversion to compound 12.
2-Bromo-6-trifluoromethyl-N-(5,8-dimethoxy-1,2,4-triazolo[1,5-c]
pyrimidine-2-yl)benzenesulfonamide (12): Compound 2 (1.42 g,
4.4 mmol) dissolved in anhydrous acetonitrile was added to a suspen-
sion of anhydrous 3,5-lutidine (2.86 g, 26.7 mmol), compound 11
(0.78 g, 5 mmol) and catalyst sulfilimine (0.10 g, 0.3 mmol). The
resultant mixture was stirred and heated to 45 °C for 24 h. The solu-
tion was cooled to room temperature, acidified by 15% sulfuric acid
(20 mL) and stirred for 30 min. A solid was precipitated from the solu-
tion, filtered, rinsed with water (50 mL) and dried in a vacuum oven at

200 JOURNAL OF CHEMICAL RESEARCH 2013
50 °C to afford compound 12 as a white powder. Yield: 1.9 g (92.7%).
m.p. 181–182 °C. 1H NMR (CDCl3, 300 MHz): δ 3.86 (s, 3H, CH3),
4.09 (s, 3H, CH3), 5.81 (s, 1H, NH), 7.60 (s, 1H, Ar H), 7.70 (t, 1H,
Ar H), 8.08–8.15 (q, 2H, Ar). IR (KBr), v/cm−1: 3431, 3247, 1637,
1572, 1537, 1513, 1398, 1374, 1293, 1177, 1153, 813, 688, 599.
ESI-MS m/z: 482.0, 484.0 [base peak, M+1, M+3]. HRMS: calcd for
C14H11BrF3N5O4S [M+H]+ 481.9745, found 481.9749.
Received 8 January 2013; accepted 23 January 2013
Paper 1301711 doi: 10.3184/174751913X13619014318618
Published online: 19 April 2013
References
1
C.J. Timothy, J.E. Robert, D.J. Richard, A.K. William, P.M. Timothy,
A.P. Mark, C.V-H. John and K.M. Richard, US Patent, 005858924 A, 1999
[Chem. Abstr. 1999, 130, 106469].
2-(2,2-Difluoroethoxy)-6-trifluoromethyl-N-(5,8-dimethoxy-1,2,4-
triazolo[1,5-c]pyrimidine-2-yl) benzenesulfonamide (1): A dry round
bottomed flask (50 mL) under N2 was charged with compound (2.5 g,
5 mmol), copper iodide (0.05 g, 0.25 mmol), 8-hydroxyquinoline
(0.073 g, 0.5 mmol) and tribasic potassium phosphate (2.12 g,
10 mmol). Difluoroethanol (8 mL) was slowly injected to the mixture.
The resultant mixture was heated to reflux for 20 h. Most of the
solvent difluoroethanol was removed under reduced pressure. The
remaining residue was diluted with ethyl acetate (50 mL), washed
with water (50 mL) and dried with anhydrous sodium sulfate. The
organic layer was collected and the solvent removed under reduced
pressure to afford crude tan oil. The oil was purified by column chro-
matography (SiO2, 0–25%, MeOH/EtOAc) to afford compound 1 as a
white solid. Yield: 1.4 g (55.3%). The spectroscopic data of the white
solid was in accordance with the reported values.3 m.p. 220–221 °C
(lit.3 223–224 °C). 1H NMR (CDCl3, 300 MHz): δ 3.85 (s, 3H, CH3),
4.06 (s, 3H, CH3), 4.46–4.54 (t, 2H, J = 12.0 Hz, CHF2), 6.34–6.70
(tt, 1H, J = 56.7 Hz), 7.58 (s, 1H, CH), 7.62–7.66 (m, 2H, J = 6.5 Hz,
Ar), 7.75–7.77 (d, 1H, J = 7.9 Hz), 11.94 (s, 1H, NH). IR (KBr),
v/cm−1: 3463, 3362, 3127, 3003, 2359, 2324, 1638, 1537, 1314, 1315,
1179, 1158, 942, 801, 630. ESI-MS m/z: 484.2 [base peak, M+1];
HRMS calcd for C16H14F5N5O5S 484.0714, found [M+H]+ 484.0716.
2
3
4
5
M.V. Subramanian, V. Loney-Gallant, J.M. Dias and L.C. Mireles, Plant
Physiol., 1991, 96, 341.
T.C. Johnson, T.P. Martin, R.K. Mann and M.A. Pobanz, Bioorg. Med.
Chem., 2009, 17, 4230.
J.A. Bond, T.W. Walker, E.P. Webster, N.W. Buehring and D.L. Harrell,
Weed Technol., 2007, 21, 961.
S.D. Willingham, G.N. Mccauley, S.A. Senseman, J.M. Chandler,
J.S. Richburg, R.B. Lassiter and R.K. Mann, Weed Technol., 2008, 22,
114.
6
7
T.W. Jabusch and R.S. Tjeerdema, J. Agric. Food Chem., 2005, 53, 7179.
D.R. Rubio, L.M. Kamp, M. Heilman, L. Williams and M.F. Rubio,
J. Agric. Food Chem., 2008, 56, 7606.
8
9
T.W. Jabusch and R.S. Tjeerdema, J. Agric. Food Chem., 2006, 54, 5958.
T.W. Jabusch and R.S. Tjeerdema, J. Agric. Food Chem., 2006, 54, 5962.
10 H. Yasuor, M.D. Osuna, A. Ortiz, N.E. Saldain, J.W. Eckert and A.J.
Fischer, J. Agric. Food Chem., 2009, 57, 3653.
11 H.J. Zhang, H.L. Cui, W.D. Zhu and S.H. Wei, Plant Protection, 2011, 37,
177.
12 G.W. Miller and F.L. Rose, J. Chem. Soc., 1963, 5642.
13 J.B. Medwid, R. Paul, J.S. Baker, J.A. Brockman, B.M. Du, W.A. Hallet,
J.W. Hanifin, R.A. Hardey, M. E. Tarrant, L.W. Torley and S. Wrenm,
J. Med. Chem., 1990, 33, 1230.
14 A.G. Michael and W.O. Eric. US Patent 20020037811 A1, 2002 [Chem.
Abstr. 2002, 136, 263172].
15 M.V. Edmonds and G.A. Roth, WO Patent 0198305A1, 2001 [Chem. Abstr.
2001, 136, 53763].
16 C. Bott, C. Hamilton and G. Roth, WO Patent 149861 A1, 2011 [Chem.
Abstr. 2011, 156, 1688].
17 G.L. Grunewald, V.M. Paradkar, B. Pazhenchevsky, M.A.Pleiss, D.J. Sall,
W.L. Seibel and T.J. Reitz, J. Org. Chem., 1983, 48, 2321.
We thank the National Natural Science Foundation of China
(No. 30973607 and No. 81172934) for financial support.
We also thank the Analytical and Testing Center of China
Pharmaceutical University for H NMR, IR, MS and HRMS
measurements.
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