Discovery of (2-benzoylethen-1-ol)-containing 1,2-benzothiazine derivatives as novel 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibiting-based herbicide lead compounds

Article abstract of DOI:10.1016/j.bmc.2015.11.032

A series of (2-benzoylethen-1-ol)-containing benzothiazine derivatives was synthesized, and their herbicidal activities were first evaluated. The bioassay results indicated that some of 3-benzoyl-4-hydroxy-2-methyl-2H-1,2-benzothiazine-1,1-dioxide derivatives displayed good herbicidal activity in greenhouse testing, especially, compound 4w had good pre-emergent herbicidal activities against Brassica campestris, Amaranthus retroflexus and Echinochloa crusgalli even at a dosage of 187.5 g ha^-1. More importantly, compound 4w displayed significant inhibitory activity against Arabidopsis thaliana HPPD and was identified as the most potent candidate with IC₅₀ value of 0.48 μM, which is better than the commercial herbicide sulctrione (IC₅₀ = 0.53 μM) and comparable with the commercial herbicide mesotrione (IC₅₀ = 0.25 μM). The structure-activity relationships was studied and provided some useful information for improving herbicidal activity. The present work indicated that (2-benzoylethen-1-ol)-containing 1,2-benzothiazine motif could be a potential lead structure for further development of novel HPPD inhibiting-based herbicides.

Full text of DOI:10.1016/j.bmc.2015.11.032

Accepted Manuscript
Discovery of (2-Benzoylethen-1-ol)-Containing 1, 2-Benzothiazine Derivatives
as Novel 4-Hydroxyphenylpyruvate Dioxygenase (HPPD) Inhibiting-Based
Herbicide Lead Compounds
Kang Lei, Xue-Wen Hua, Yuan-Yuan Tao, Yang Liu, Na Liu, Yi Ma, Yong-
Hong Li, Xiao-Hua Xu, Chui-Hua Kong
PII:
S0968-0896(15)30156-5
DOI:
http://dx.doi.org/10.1016/j.bmc.2015.11.032
BMC 12680
Reference:
Bioorganic & Medicinal Chemistry
To appear in:
Received Date:
Revised Date:
Accepted Date:
14 October 2015
23 November 2015
24 November 2015
Please cite this article as: Lei, K., Hua, X-W., Tao, Y-Y., Liu, Y., Liu, N., Ma, Y., Li, Y-H., Xu, X-H., Kong, C-
H., Discovery of (2-Benzoylethen-1-ol)-Containing 1, 2-Benzothiazine Derivatives as Novel 4-
Hydroxyphenylpyruvate Dioxygenase (HPPD) Inhibiting-Based Herbicide Lead Compounds, Bioorganic &
Medicinal Chemistry (2015), doi: http://dx.doi.org/10.1016/j.bmc.2015.11.032
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Discovery of (2-Benzoylethen-1-ol)-Containing 1, 2-Benzothiazine Derivatives as Novel
4-Hydroxyphenylpyruvate Dioxygenase (HPPD) Inhibiting-Based Herbicide Lead
Compounds
Kang Lei,a,b Xue-Wen Hua,a,b Yuan-Yuan Tao,a,b Yang, Liu,a,b Na, Liu,a,b Yi Ma,a Yong-Hong Li,a
Xiao-Hua Xu,*a,b and Chui-Hua Kongc
a State Key Laboratory of Elemento-Organic Chemistry, Institute of Elemento-Organic Chemistry,
Nankai University, Tianjin, China
b Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China
c College of Resources and Environmental Sciences, China Agricultural University, Beijing, China
* Correspondence to: Xiao-Hua Xu, E-mail: xiaohuaxu@nankai.edu.cn
1

Abstract: A series of (2-benzoylethen-1-ol)-containing benzothiazine derivatives was synthesized,
and their herbicidal activities were first evaluated. The bioassay results indicated that some of
3-benzoyl-4-hydroxy-2-methyl-2H-1, 2-benzothiazine-1, 1-dioxide derivatives displayed good
herbicidal activity in greenhouse testing, especially, compound 4w had good pre-emergent
herbicidal activities against Brassica campestris, Amaranthus retroflexus and Echinochloa
crusgalli even at a dosage of 187.5 g ha-1. More importantly, compound 4w displayed significant
inhibitory activity against Arabidopsis thaliana HPPD and was identified as the most potent
candidate with IC50 value of 0.48 μM, which is better than the commercial herbicide sulctrione
(IC50 = 0.53 μM) and comparable with the commercial herbicide mesotrione (IC50 = 0.25 μM). The
structure-activity relationships was studied and provided some useful information for improving
herbicidal activity. The present work indicated that (2-benzoylethen-1-ol)-containing 1,
2-benzothiazine motif could be a potential lead structure for further development of novel HPPD
inhibiting-based herbicides.
Keywords: Synthesis; Benzothiazine; Herbicide activity; 4-Hydroxyphenylpyruvate dioxygenase;
Structure-activity relationships
2

1. Introduction
4-Hydroxyphenylpyruvate dioxygenase (HPPD) is a member of the class of non-heme iron
oxygenase enzymes.1–3 It catalyzes the conversion of 4-hydroxyphenylpyruvate (HPP) to
homogentisate (HGA) and carbon dioxide in the presence of oxygen and ferrous ion.4–7 In plants,
HGA formed by the action of HPPD is utilized as the aromatic precursor for tocopherols and
plastoquinone.8 Plastoquinone is the redox cofactor for phytoene desaturase, a key enzyme in the
biosynthesis of photoprotectant carotenoids. Thus, the inhibition of HPPD prevents the normal
functioning of phytoene desaturase in the synthesis of carotenoids, which will result in unique
bleaching symptom in sunlight and finally caused necrosis and death of plants.7, 9–11
For many years, HPPD has been an important target of interest in the agrochemical industry,
and many efforts have been made in the screening and synthesis of HPPD inhibitors, which have
lead to a considerable number of HPPD inhibiting-based herbicides. 12–18 Thus far, some of HPPD
inhibiting-based herbicides (Fig. 1), such as mesotrione, sulcotrione, tefuryltrione, tembotrione,
topramezone and pyrasulfotole, have reached the market place. HPPD inhibiting-based herbicides
show many advantages, such as low application rate, low toxicity, broad-spectrum weed control,
excellent crop selectivity and safety towards the environment.13,15,17 A survey of the known HPPD
inhibiting-based herbicides revealed that most of them have the same structural characteristic, i.e.,
the common chemical motif of them is the presence of (2-benzoylethen-1-ol) (Fig. 1) as the
minimum substructure, which can bind to the iron(II) of HPPD.19 An extensive review of the
literature on HPPD inhibiting-based herbicides indicated that modification of the benzoyl group is
an effective way to obtain new derivatives with improved herbicidal activity.13,20,21 Based on the
above fact, we become interesting in synthesizing and evaluating the herbicidal activities of
various compounds that contains (2-benzoylethen-1-ol) substructure to find novel HPPD
inhibiting-based herbicides.
Figure 1. Chemical structures of the commercially HPPD inhibiting-based herbicides and
their common substructure
1, 2-Benzothiazines is a heterocyclic scaffold of paramount importance in drug chemistry.
During last decades, many 1, 2-benzothiazine derivatives had been successfully synthesized and
patented for
a
wide range of biological activities, including anti-inflammatory,22–27
antimicrobial,28 antiallergic29, antidepressant30 and antithrombotic31 properties. Recently,
pyrazolo-containing 1, 2-benzothiazine derivatives were reported as potent hepatitis C virus (HCV)
3

replication inhibitors and anti-HIV-1 agents.32,33 Although the derivatives of 1, 2-benzothiazine
have been extensively studied in medical chemistry, examinations of them as agrochemicals are
still very scarce, especially with respect to their herbicidal activities. As a continuation of our
work on synthesizing and evaluating the herbicidal activities of compounds that contain
(2-benzoylethen-1-ol)
substructure,34
we
have
synthesized
a
series
of
(2-benzoylethen-1-ol)-containing 1, 2-benzothiazine derivatives. Herein, we wish to report the
detailed synthesis, herbicidal activities and in vitro HPPD inhibitory activity of a series of
3-benzoyl-4-hydroxy-2-methyl-2H-1, 2-benzothiazine-1, 1-dioxide derivatives (Fig. 2 I).35 For
comparison, a series of 3-benzoyl-4-hydroxy-1-methyl-1H-2, 1-benzothiazine-2, 2-dioxide
derivatives (Fig. 2 II) were also synthesized and their herbicidal activities were evaluated to
discuss the structure–activity relationships (SARs). To the best of our knowledge, this is the first
report on the herbicidal activities of (2-benzoylethen-1-ol)-containing benzothiazine derivatives.
Figure 2. Chemical structures of I and II
2. Methods and materials
Unless otherwise stated, all reactions were carried out under an argon atmosphere, and all
1
commercially available reagents were used without further purification. H NMR and 13C NMR
were obtained at 400 MHz and 100 MHz, respectively, using Bruker AV400 spectrometer in
CDCl3 or DMSO-d6 solution with TMS as the internal standard. Chemical shifts are given in δ
values. Coupling constants were reported in Hertz (Hz). High-resolution mass spectra were
conducted using an Ionspec 7.0T spectrometer by ESI-FTICR technique. The single-crystal
structure of compounds 4o and 15a were determined on a Rigaku Saturn 724 CCD area-detector
diffractometer. The melting points were determined on an X-4 binocular microscope melting point
apparatus (Beijing Tech Instruments Co., Beijing, China) and were uncorrected.
2.1. X-ray diffraction
Compounds 4o and 15a were recrystallised from a mixture of chloroform and methanol to
afford a suitable single crystal. Crystallographic data for compounds 4o and 15a had been
deposited with the Cambridge Crystallographic Data Centre as supplementary publications with
the deposition numbers 1425395 and 1425396, respectively. The data can be obtained free of
charge from http://www.ccdc.cam.ac.uk/.
2.2. Herbicidal activities
2.2.1. Inhibition of the root growth of rape (Brassicacampestris L.)36-38
Emulsions of target compounds and mesotrione were prepared by dissolving them in 100 μL of
DMF adding a few drops of Tween-80 and dispersing in water. A mixture of the same amount of
water, DMF and Tween-80 was used as control. 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 and allowed to germinate for 65 h at 28 ± 1 °C. The lengths of ten rape roots randomly
selected from each plate were measured, and the means were calculated. The percentage of
inhibition was used to describe the control efficiency of the compounds. Each treatment was
4

performed triplicate.
2.2.2. Inhibition of the seedling growth of Barnyard Grass [Echinochloa crusgalli (L.)
Beauv.]36-38
Emulsions of target compounds and mesotrione were prepared according to above method. A
mixture of the same amount of water, DMF and Tween-80 was used as control. Ten Echinochloa
crusgalli 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, and the seeds were allowed to germinate for 65 h at 28 ± 1 °C. 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.
Each test was performed in triplicate.
2.2.3. Greenhouse Tests37,38
Emulsions of the test compounds and mesotrione were prepared according to above method.
The emulsions were sprayed using a laboratory belt sprayer at 750 L ha−1. All the experiments
were performed under natural light conditions at 18 – 28 °C. Additionally, adverse weather
lighting was provided using sodium vapour lamps with a 12 : 12 h light : dark photoperiod.
2.3. Preparation of HPPD and the Evaluation of HPPD Inhibitors
Recombinant Arabidopsis thaliana HPPD (AtHPPD) was prepared and purified according the
reported method.39-44 Our coupled enzyme assays for the in vitro activity and inhibition of HPPD
were measured by a modification of methods previously reported in the literature.45 Assays were
performed in 96-well plates at 30 °C using a UV/Vis plate reader to monitor the formation of
maleylacetoacetate at 318nm (ɛ330=13500 M−1 cm−1). Before assays were conducted, all reaction
components were pre-equilibrated at 30 °C for at least 10 min. The inhibitor and HPPD were
preincubated for 20 min to reach a steady state in practical kinetic measurement, followed by the
addition of a mixture of appropriate amounts of HPPA, 100 μM of FeCl2, 2 mM of sodium
ascorbate, 50 mM of HEPES buffer (pH 7.0) and HGD (150 nM). The amount of HGD activity
was predetermined to be in large excess of the HPPD activity to ensure that the reaction was
tightly coupled. Each experiment was repeated at least 3 times and the values were averaged.
HPPD inhibitors were dissolved in dimethyl sulfoxide (DMSO) for stock solution and diluted to
various concentrations with reaction buffer just before use. The IC50 values were then calculated
based on the plot of plotting the residue activity against the concentration of inhibitor at certain
concentrations of substrate.
2.4. Computational Methods
Molecular modeling was performed using SYBYL 6.91 software, and the comparative
molecular field analysis (CoMFA) method has been performed according to our previous papers.
46,47 The herbicidal activities of 23 compounds (compounds 4a-4w, for training sets compounds)
against Brassica campestris at 1500 g ha-1 under post-emergence condition used to derive the
CoMFA analyses model were listed in Table 5. The activity was expressed in terms of ED by the
formula ED=log [I/(100 - I)×MW], where I is the percent control efficacy and MW is the
molecular weight of the tested compounds. The compound 4o, owing to the determination of the
crystal structure, was used as a template to build the other molecular structures. Each structure
was fully geometry-optimized using a conjugate gradient procedure based on the TRIPOS force
field and Gasteiger and Hückel charges. Because these compounds share a common skeleton, 23
atoms marked with an asterisk were used for root-mean-square (RMS) fitting onto the
5

corresponding atoms of the template structure. CoMFA steric and electrostatic interaction fields
were calculated at each lattice intersection on a regularly spaced grid of 2.0 Ǻ. The grid pattern
was generated automatically by the SYBYL/CoMFA routine, and an sp3 carbon atom with a van
der Waals radius of 1.52 Ǻ and a +1.0 charge was used as the probe to calculate the steric
(Lennard-Jones 6-12 potential) field energies and electrostatic (Coulombic potential) fields with a
distance-dependent dielectric at each lattice point. Values of the steric and electrostatic fields were
truncated at 30.0 kcal/mol. The CoMFA steric and electrostatic fields generated were scaled by the
CoMFA-STD method in SYBYL. The electrostatic fields were ignored at the lattice points with
maximal steric interactions. A partial least-squares approach was used to derive the 3D QSAR, in
which the CoMFA descriptors were used as independent variables and ED values were used as
dependent variables. The cross-validation with the leave-one-out option and the SAMPLS
program, rather than column filtering, was carried out to obtain the optimal number of components
to be used in the final analysis. After the optimal number of components was determined, a
non-cross-validated analysis was performed without column filtering. The modeling capability
(goodness of fit) was judged by the correlation coefficient squared, r2, and the prediction
capability (goodness of prediction) was indicated by the cross-validated r2 (q2).
3. Results and discussion
3.1. Chemistry
As shown in Scheme 1 (Path A), compounds 4a–4i were synthesized according to the reported
methods.33,35,48 Saccharin sodium salt
1 was reacted with α-bromo ketone in N,
N-dimethylformamide (DMF) to provide the alkylated products 2a–2i in excellent yield.
Gabriele-Colman type ring expansion of the five-membered isothiazole ring of compounds 2a–2i
to the six-membered thiazine ring yielded compounds 3a–3i, which were further reacted with
methyl iodide under base condition to result in the target products 4a–4i. Target compounds
4j–4w were synthesized according to our developed method (Scheme 1 Path B). The key mediate
compound 8 was first synthesized according to the reported method,49 with slight modification. By
reacting saccharin sodium salt 1 with methyl chloroacetate in DMF under reflux conditions,
methyl [1, 1-dioxido-3-oxo-1, 2-benzisothiazol-2(3H)-yl]acetate 5 was obtained in excellent yield.
Gabriele-Colman type ring expansion of compound 5 yielded methyl 4-hydroxy-2H-1,
2-benzothiazine-3-carboxylate 1, 1-dioxide 6. Compound 6 was refluxed with concentrated
hydrochloric acid to get 2H-1, 2-benzothiazin-4(3H)-one 1, 1-dioxide 7, which were further
reacted with methyl iodide and cesium carbonate under mild condition to result in 2-methyl-2H-1,
2-benzothiazin-4(3H)-one 1, 1-dioxide 8. Subsequently, intermediate compounds 9a–9n were
synthesized by the reaction of compound 8 with a series of benzoic acid derivatives in the
presence of sodium hydride (NaH) in DMF, which was treated with potassium cyanide (KCN) and
18-crown-6 at ambient temperature to give the target compounds 4j–4w.
As shown in Scheme 2, target compounds 15a–15j were synthesized according to the reported
methods.50-52 1-Methyl-1H-2, 1-benzothiazin-4(3H)-one 2, 2-dioxide 13 was synthesized by
condensation of methane sulfonyl chloride with methyl anthranilate followed by N-methylation
and base catalyzed cyclization. Subsequently, compounds 14a–14j were synthesized by the
reaction of compound 13 with a series of benzoyl chloride derivatives in the presence of NaH in
DMF, which was treated with KCN and 18-crown-6 at ambient temperature to give the target
compounds 15a–15j.
1
The structures of all target compounds were confirmed by H NMR, 13C NMR and HRMS
6

spectral data. In addition, the crystal structures of 4o and 15a were further determined by X-ray
diffraction analysis (CCDC 1425395 and CCDC 1425396; Fig. 3).
O
Path A
R
Br
OH
O
OH O
O
O
O
R
R
NaOH, CH3I
MeOH/H2O
Na, MeOH
Reflux
NNa+
N
NH
N
DMF
R
S
S
S
S
O
O
O
O
O
O
O
O
4a-4i
1
2a-2i
3a-3i
2a,3a,4a R=H
2f,3f,4f R=4-F
2b,3b,4b R=3-F
2c,3c,4c R=3-Cl
2d,3d,4d R=3-Br
2e,3e,4e R=3-OMe
2g,3g,4g R=4-Cl
2h,3h,4h R=4-Br
2i,3i,4i R=4-OMe
Path B
O
OH
O
O
O
O
O
ClCH2COOMe
DMF, Reflux
Na, MeOH
Reflux
HCl, Reflux
O
NNa+
O
N
NH
NH
S
S
O
S
O
S
O
O
O
O
O

5
6
7
O
N
R
O
OH O
O
CH3I,DMF
Cs2CO3
NaH, DMF
Et3N, KCN
R
N
N
18-crown-6
DCM
S
S
O
O
S
O
O
Cl
O
O
R
O
8
9a-9n
4j-4w
9a,4j R=4-NO2
9h,4q R=2-Cl-4-F
9b,4k R=4-SO2Me
9c,4l R=2-Cl-3-Cl
9d,4m R=2-Cl-5-Cl
9e,4n R=3-Cl-4-Cl
9f,4o R=3-Cl-5-Cl
9g,4p R=2-Cl-4-Cl
9i,4r R=2-Cl-4-Br
9j,4s R=2-Br-4-Cl
9k,4t R=2-Br-4-Br
9l,4u R=2-Cl-4-NO2
9m,4v R=2-Cl-4-CF3
9n,4w R=2-Cl-4-SO2Me
Scheme 1. The synthetic route of target compounds 4a–4w
O
O
O
O
MsCl, Py
DMF, rt
CH3I, Cs2CO3
DMF, rt
NaH
O
O
O
DMF,rt
S O
O
N
NH2
NHMs
N
O S O
10
11
12
13
O
R
OH
O
O
O
N
R
NaH, DMF
Et3N, KCN
S
18-crown-6
DCM
O
N
S
O
O
Cl
R
O
14a-14j
14a,15a R=H
14b,15b R=4-F
14c,15c R=4-Cl
14d,15d R=4-Br
14e,15e R=4-OMe
15a-15j
14f,15f R=4-NO2
14g,15g R=4-SO2Me
14h,15h R=2-Cl-4-Cl
14i,15i R=2-Cl-4-F
14j,15j R=2-Cl-4-Br
Scheme 2. The synthetic route of target compounds 15a–15l
7

Figure 3. Crystal structures of 4o (left) and 15a (right)
3.2. Herbicidal activity in vitro and preliminary SARs study
The herbicidal activities of compounds 4a–4w and 15a–15j were preliminary determined with
Brassica campestris root test and Echinochloa crusgalli cup test. Also, the herbicidal activities of
intermediate compounds 3a–3i were evaluated. Mesotrione was selected as a positive control. The
bioassay results were shown in Table 1. It was found that most of the target compounds 4a–4w
showed good herbicidal activities against Brassica campestris and Echinochloa crusgalli at 100
μg mL-1, especially, compound 4p was the most active compound with 90.0% and 100%
inhibition against Brassica campestris and Echinochloa crusgalli at 100 μg mL-1, respectively,
superior even to mesotrione. Compounds 3a–3i and 15a–15j showed moderate herbicidal
activities against Brassica campestris at 100 μg mL-1, but showed very low or even no herbicidal
activities against Echinochloa crusgalli. Parallel activity contrasting between compounds 3a–3i
and 4a–4i against Brassica campestris and Echinochloa crusgalli at 100 μg mL-1 were performed.
As shown in (Fig. 4A), series 4 always displayed better herbicidal activities against Brassica
campestris and Echinochloa crusgalli at 100 μg mL-1 than that of series 3 in a whole, indicating
that the methyl group at the N-2 position of the ring B would be essential for herbicidal activity.
Subsequently, parallel activity contrasting between compounds 4a, 4f–4k, 4p–4r and compounds
15a–15j was performed. (Fig. 4B) It was found that that series 4 had better herbicidal activities
against Brassica campestris and Echinochloa crusgalli at 100 μg mL-1 than that of series 15 in a
whole, indicating that the position between NCH3 group and O=S=O group was very important for
herbicidal activity.
Table 1. Herbicidal Activity of Compounds 3a–3e, 4a–4l and 15a–15j (Percent Inhibition) a
OH O
OH O
OH O
2

5
2
5
2
R
R
R
3
4
3
3
C
B
N
S
O O
O
S
NH
S
O O
4
4
N
O
5
3
4
15
Brassica campestris root test
Echinochloa crusgalli cup test
Comp.
R
H
10 µg mL-1
100 µg mL-1
10 µg mL-1
100 µg mL-1
15.4±1.1
30.4±0.4
23.6±1.0
21.4±1.3
3a
3b
3c
3d
0
0
0
0
0
8.8±0.4
3-F
3-Cl
3-Br
53.4±0.6
76.8±0.8
61.7±1.2
13.9±0.7
19.6±0.4
5.0±0.3
8

3e
3f
3-OMe
4-F
39.1±0.7
73.0±1.8
33.1±1.4
60.5±0.7
44.7±0.2
12.6±0.5
67.9±0.7
87.3±2.1
87.4±1.0
86.6±0.6
75.9±0.9
72.4±1.3
93.4±0.8
70.2±0.6
0
0
8.2±0.7
8.2±0.4
7.7±0.6
0
0
0
15.3±1.8
29.3±1.0
22.6±0.7
13.2±1.0
28.3±1.6
81.2±0.8
84.9±0.9
71.5±1.9
49.5±0.8*
58.5±1.3
88.6±1.8
59.3±0.6
18.6±1.2
39.8±0.9*
37.6±1.5*
26.4±0.4*
40.7±1.2*
13.5±1.6
29.3±0.5
100
3g
4-Cl
0
3h
4-Br
0
3i
4-OMe
H
0
4a
9.0±0.5
12.5±1.1
29.0±0.9
16.9±0.4
13.6±0.3
0
4b
3-F
36.2±0.8
4c
3-Cl
18.7±0.9
4d
3-Br
20.7±0.4
4e
3-OMe
4-F
0
4f
55.3±2.0
14.0±1.1
25.2±1.6
9.1±0.7
0
4g
4-Cl
47.3±1.5
4h
4-Br
0
4i
4-OMe
4-NO2
4-SO2Me
2-Cl-3-Cl
2-Cl-5-Cl
3-Cl-4-Cl
3-Cl-5-Cl
2-Cl-4-Cl
2-Cl-4-F
2-Cl-4-Br
2-Br-4-Cl
2-Br-4-Br
2-Cl-4-NO2
2-Cl-4-CF3
2-Cl-4-SO2Me
H
0
4j
40.2±0.7
95.6±1.1
94.8±0.7
79.6±0.9
78.8±1.7
0
11.6±0.9
19.7±0.7
17.8±0.7
16.9±1.4
0
4k
43.4±0.5
4l
0
4m
4n
0
0
4o
0
23.3±1.8
90.0±1.3
84.3±1.5
88.4±2.1
76.4±0.6
74.0±1.2
71.6±1.4
87.3±0.3
82.1±0.9
31.0±0.6
51.9±0.8
68.5±1.3
65.6±1.5
85.2±2.0
34.9±1.9
23.0±0.9
78.7±0.7
65.6±1.4
71.3±0.5
89.7±1.2
22.3±1.1
37.7±0.8*
17.4±0.9*
34.3±1.6*
26.3±0.8*
30.8±1.2*
21.1±1.1*
50.7±0.9*
54.8±1.0*
0
4p
42.8±0.9
4q
26.9±1.1
79.3±0.6**
80.2±2.4**
81.7±1.3**
100
4r
0
4s
0
4t
12.8±1.8
4u
18.0±0.6
69.5±0.6**
80.7±0.2**
85.6±0.8**
0
4v
43.7±2.3
4w
15a
15b
15c
15d
15e
15f
15g
15h
15i
15j
Mesotrione
16.4±1.7
0
4-F
0
0
0
4-Cl
0
0
0
4-Br
0
0
0
0
4-OMe
4-NO2
4-SO2Me
2-Cl-4-Cl
2-Cl-4-F
2-Cl-4-Br
/
0
0
0
0
0
0
0
0
23.4±0.9
10.6±0.5
7.4±0.8
80.3±0.4
0
12.0±0.4
10.7±0.7
13.1±1.1
90.5±2.1**
0
0
85.8±0.6**
a Each value represents the average of three experiments; * Partial bleaching symptom; **
Complete bleaching symptom
9

Figure 4. Parallel activity contrasts between compounds 3a–3i and compounds 4a–4i, between
compounds4a, 4f–4k, 4p–4r and compounds 15a–15j against Brassica campestris (left) and
Echinochloa crusgalli (right). The inhibition activity was tested at 100 μg mL-1 and expressed in
ordinate
It was very interesting that the treated Echinochloa crusgalli by some compounds developed
bleaching symptom, especially, compounds 4q–4s and 4u–4w had made Echinochloa crusgalli
bleached completely, which possibly implying these compounds had the similar herbicide
mechanism with mesotrione. Noteworthy, the treated Echinochloa crusgalli by compounds
15h–15j did not develop the bleaching symptom as the corresponding isomers 4p–4r, possibly
implying the position between NCH3 group and O=S=O group had important impact on the
herbicide mechanism.
3.3. Herbicidal activity in greenhouse tests and further SARs study
Based on the above bioassay results, compounds 4a–4w were chosen to test on four species
representative of monocotyledonous and dicotyledonous plants at a dosage of 1500 g ha-1 in the
glasshouse. As the bioassay data shown in Table 2, some of the target compounds, such as
compounds 4p, 4r, 4s and 4t–4w, were found to display good herbicidal activities. We were
encouraged to observe that compound 4w displayed 100 % inhibition activities against all weeds
tested under the pre-emergence condition, equal to the commercial herbicide mesotrione;
compounds 4v also exhibited 100 % control against Brassica campestris, Amaranthus retroflexus
and Echinochloa crusgalli under the pre-emergence condition. It was very interesting that the
treated monocotyledonous plants Echinochloa crusgalli and Digitaria sanguinalis by compound
4w developed bleaching symptom, followed by necrosis, which indicated the typical
characteristics of HPPD-inhibiting based herbicides.
Subsequently, the most activity compound 4w against all weeds tested under pre-emergence
condition were further measured using dose reduction with serial two-fold dilution. As the results
10

shown in Table 3, the herbicidal activities of compound 4w became progressively lower against
Echinochloa crusgalli and Digitaria sanguinalis at concentrations of 750 g ha-1, 375 g ha-1 and
187.5 g ha-1, whereas the control compound mesotrione still showed 100 % inhibition at these
concentrations. The results indicated that compound 4w had lower herbicidal activity than the
commercial herbicide mesotrione. The present compound showed good herbicidal activities with
92.0 %, 89.8 % and 80.4 % inhibition against Brassica campestris, Amaranthus retroflexus and
Echinochloa crusgalli even at a dose of 187.5 g ha-1, respectively, which comparable with
mesotrione, indicating that compound 4w had certain herbicidal activity and could be served as a
lead compound for further optimization.
Table 2. Herbicidal Activity of Compounds (Percent Inhibition) (Rate=1500 g ha-1)a
Brassica
Amaranthus
retroflexus
Echinochloa
crusgalli
Digitaria
campestris
sanguinalis
Comp.
pre
post
pre
0
post
31.2±1.7
28.8±0.6
55.2±1.0
70.7±1.9
36.8±2.0
45.6±0.7
55.4±1.1
27.7±1.0
0
pre
post
pre
post
0
13.3±1.4
5.0±0.5
5.0±0.7
0
18.1±0.7
44.9±1.0
46.7±1.1
30.3±1.7
39.6±0.9
37.3±1.4
37.7±1.5
71.8±1.0
0
0
0
0
0
4a
4b
4c
4d
4e
4f
47.6±0.8
0
0
0
0
0
0
27.5±1.3
0
18.0±0.6
6.8±0.5
59.6±0.9
29.9±1.6
35.9±1.7
69.1±0.9
59.6±0.8
0
55.1±1.2
28.3±1.4
0
0
20.2±1.3
0
38.0±0.8
5.1±1.0
9.6±1.5
0
0
10.0±0.6
19.7±1.3
0
0
21.9±1.1
19.0±0.6
10.0±0.5
0
0
33.3±1.2
4g
4h
4i
0
18.5±1.4
0
0
0
0
0
0
0
0
0
0
0
46.4±0.9
50.2±1.3
85.5±0.8
78.6±1.7
0
20.7±1.3
16.9±0.7
56.9±1.2
95.9±1.0
0
44.0±0.8
41.4±1.4
44.8±1.5
39.2±0.9
0
0
7.1±0.9
0
5.0±0.5
27.4±0.8
0
0
4j
7.0±0.9
12.9±1.7
57.0±1.4
0
11.6±1.6
20.0±0.4
22.5±0.6
0
4k
4l
0
24.0±1.6
0
4m
4n
4o
4p
4q
4r
4s
0
0
0
0
0
0
0
0
100
100
96.1±0.7
47.6±1.4
85.8±0.5
77.2±2.0
94.0±0.9
82.2±1.5
100
58.6±1.0
48.8±1.1
28.8±1.4
31.4±1.3
54.0±1.6
38.4±2.0
85.6±1.2
90.4±0.6
100
78.8±1.0*
73.7±0.8
94.1±1.1
61.0±1.0
44.8±1.2*
100
26.6±1.1**
13.4±1.0*
67.7±1.4*
17.3±0.8*
6.6±1.2**
47.6±2.3*
81.0±0.6*
93.0±1.4**
100
81.8±0.9* 51.3±1.1*
38.4±2.2
77.4±1.1
81.7±1.3
100
53.8±2.0
91.4±0.6
93.3±1.2
87.4±1.0
96.8±0.7
100
47.3±1.4
71.4±1.9
77.1±0.9
20.0±0.5
0
11.4±0.7
61.8±1.1* 41.8±0.9*
4t
100
0*
31.7±2.1
100
37.5±1.8
13.3±1.7*
58.0±1.3*
100
4u
4v
4w
100
100
100
100
100
100
100
100
100
100
100
Mesotrione
a
Each value represents the average of three experiments; * Partial bleaching symptom; **
Complete bleaching symptom
Table 3. Further herbicidal testing of compound 4w (pre-emergence)
Rate (g
ha-1)
750
Brassica
campestris
100
Amaranthus
retroflexus
100
Echinochloa
crusgalli
100
Digitaria
sanguinalis
74.6±1.6**
29.4±0.7*
Comp.
4w
375
100
100
94.7±0.6**
11

187.5
750
92.0±1.7
100
89.8±1.4
100
80.4±1.0**
100
20.0±1.1
100
mesotrione
375
100
100
100
100
187.5
100
100
100
100
a
Each value represents the average of three experiments; * Partial bleaching symptom; **
Complete bleaching symptom
Based on the bioassay data in greenhouse tests, SARs was discussed. It was found that the
changes of substituent on the benzene ring A affected the herbicidal activity. To better understand
the SARs for herbicidal activity, CoMFA was performed. Brassica campestris data of compounds
4a–4w at 1500 g ha-1 under post-emergence condition was used to derive the CoMFA analyses
model. As listed in Table 4, a predictive CoMFA model was established with the conventional
correlation coefficient r2 = 0.963 and the cross-validated coefficient q2 = 0.798. The contributions
of steric and electrostatic fields are 68.1 % and 31.9 % as shown in Figure 5, respectively. The
observed and calculated activity values are listed in Table 5. The models showed a good
predictability on these compounds.
Table 4. Summary of CoMFA analysis
Contribution
r2
q2
Compound
steric electrostatic
68.1 % 31.9 %
CoMFA 0.963 0.798
4s
Table 5. Experimental and calculated activity of compounds in training set and test set
Compounds
ED
PDCoMFA
20.44
44.07
42.38
29.21
39.10
33.54
50.05
45.72
0
Compounds
ED
78.60
0
PDCoMFA
65.16
0
4a
4b
4c
4d
4ea
4f
18.10
44.90
46.70
30.30
39.60
37.30
52.70
37.70
0
4m
4n
4o
4p
4q
4ra
4s
0
0
99.90
53.80
91.40
93.30
87.40
96.80
99.90
99.90
83.52
67.22
94.27
90.01
96.07
98.23
97.18
92.47
4g
4h
4i
4ja
4k
4l
4t
4ua
4v
4w
46.40
50.20
85.50
45.23
56.21
88.13
ED: experimental value; PDCoMFA: predictive value by CoMFA; a Represent the compounds in test
set
Figure 5. (A) Steric maps from the CoMFA model. (B) Electrostatic maps from the CoMFA
12

model
The steric field contour map is plotted in Figure 5A. The green displays a position where a
bulky group would be favorable for higher herbicidal activity. As shown in Figure 5A, the
CoMFA steric contour plots obviously indicated that a green region is located around the
2-positions of the benzene ring. This means that the bulky substituents at 2-positions will increase
the herbicidal activity. The electrostatic contour plot is shown in Figure 5B. The blue contour
defines a region where an increase in the positive charge will result in an increase in the activity,
whereas the red contour defines a region of space where increasing electron density is favorable.
As shown in Figure 5B, the target compounds bearing an electron-withdrawing group at the 2- or
4-position of the benzene ring and an electron-donating group at the 3-position displayed higher
activity. These results provide useful information for improving herbicidal activity.
3.4. In Vitro HPPD Inhibitory Activity
As mentioned above, the treated Echinochloa crusgalli and Digitaria sanguinalis by some
compounds, such as compounds 4p–4w, caused significant bleaching symptom. Thus, it was
speculated that these compounds would be served as potential HPPD inhibitors. In order to prove
this conjecture, the in vitro HPPD inhibitory activities of compounds 4p–4w were evaluated
subsequently. As shown in Table 6, most of compounds 4p–4w displayed significant inhibitory
activity against the AtHPPD. For example, compounds 4p, 4t and 4w showed good potency with
IC50 value of 0.69 μM, 0.86 μM and 0.48 μM, respectively. Compound 4w was identified as the
most potent candidate with IC50 value of 0.48 μM against AtHPPD, which is better than the
commercial herbicide sulctrione and comparable with mesotrione. These results indicated that
compound 4w could be a potential lead compound for further development of novel HPPD
inhibiting-based herbicide.
Table 6. Biological activity of compounds 4p–4w against AtHPPD
Compounds
IC50 (μM)
Compounds
IC50 (μM)
4p
0.69 ± 0.031
1.44 ± 0.087
1.66 ± 0.087
1.37 ± 0.045
0.25 ± 0.012
4t
4u
0.86 ± 0.045
1.13 ± 0.069
1.57 ± 0.090
0.48 ± 0.024
0.53 ± 0.055
4q
4r
4v
4s
4w
Mesotrione
4. Conclusion
Sulctrione
In conclusion, a series of 3-benzoyl-4-hydroxy-2-methyl-2H-1, 2-benzothiazine-1, 1-dioxide
and 3-benzoyl-4-hydroxy-1-methyl-1H-2, 1-benzothiazine-2, 2-dioxide derivatives were
synthesized, and their herbicidal activities were firstly evaluated. The preliminary herbicidal
results indicated that most of 3-benzoyl-4-hydroxy-2-methyl-2H-1, 2-benzothiazine-1, 1-dioxide
derivatives showed good herbicidal activities against Brassica campestris and Echinochloa
crusgalli at a concentration of 100 μg mL-1. The preliminary study of structure–activity
relationships indicated that the methyl group at the N-2 position of the ring B, and the position
between NCH3 group and SO2 group played an important role on the herbicidal activity. The
results of greenhouse experiments showed that compounds 4w displayed good pre-emergent
herbicidal activities against Brassica campestris, Amaranthus retroflexus and Echinochloa
crusgalli even at a dosage of 187.5 g ha-1, which is comparable with the commercial herbicide
mesotrione. Most surprisingly, compounds 4w showed the best HPPD inhibition activity with an
IC50 value of 0.47 μM, which is better than the commercial herbicide sulctrione (IC50 = 0.53 μM)
13

and comparable with mesotrione (IC50 = 0.25 μM). The promising results suggested that
compound 4w is well worth further optimization as a potential HPPD inhibiting-based herbicide
lead compound. Further structural optimization of compound 4w is still ongoing.
5. Experiment
5.1. General procedure for compounds (2a-2i):
A mixture of 1 (2.0 g, 10 mmol) and α-bromoacetophenone (2.0 g, 10 mmol) in N,
N-dimethylformamide (DMF) (20 mL) was taken in a round bottom flask and was heated at
100 °C for 1 h. Contents were then cooled to room temperature and poured over ice cooled water
(100 ml) resulting in the formation of a light yellow solid, which was filtered to give desired
product 2a (2.5 g, yield: 83 %). The rest of compounds were prepared by the similar procedure to
2a.
5.2. General procedure for compounds (3a-3i):
Sodium metal (0.5 g, 21 mmol) and dry methanol (20 ml) was allowed to reflux until all the
metal dissolved. To this solution, 2a (2.5 g, 8.4 mmol) was added in a single portion. Temperature
of the mixture was maintained at 55 °C for 30 min till the completion of reaction. The contents
were then cooled to 5 °C and poured over an ice-water mixture. Hydrochloric acid (2 N) was
added to the mixture till the pH became approximately 3. The precipitates formed were filtered
and dried to get the product 3a as a yellow solid (2.0 g, yield: 80 %). The rest of compounds were
prepared by the similar procedure to 3a.
5.3. General procedure for compounds (4a-4i):
Compound 3a (2.0 g, 6.7 mmol) was dissolved in ethanol (10 mL) and was treated with
aqueous sodium hydroxide (1 M, 7.4 mL) followed by iodomethane (1.0 g, 6.7 mmol) and was
stirred at room temperature for 12 h. Hydrochloric acid (2 N) was added to the mixture till the pH
became approximately 3. The resulting suspension was filtered, and the solid was washed with
water and dried to give desired product 4a as a yellow solid (1.7 g, yield: 79 %). The rest of
compounds were prepared by the similar procedure to 4a.
Data for (4a): yield 79 %; yellow solid; m.p. 160–162 °C; 1H NMR (400 MHz, CDCl3) δ: 15.83
(s, 1H), 8.26 – 8.21 (m, 1H), 8.20 – 8.16 (m, 2H), 7.97 – 7.92 (m, 1H), 7.86 – 7.79 (m, 2H), 7.66 –
7.60 (m, 1H), 7.54 (t, J = 7.6 Hz, 2H), 2.71 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 190.9, 169.3,
136.3, 134.9, 133.7, 132.9, 129.4, 128.8, 128.6, 127.8, 124.3, 118.8, 40.0; HRMS: calcd for
C16H13NO4S [M+H]+ 316.0565, found 316.0640.
Data for (4b): yield 82 %; yellow solid; m.p. 142–143 °C; 1H NMR (400 MHz, CDCl3) δ: 15.69
(s, 1H), 8.24 – 8.22 (m, 1H), 8.04 (d, J = 7.8 Hz, 1H), 7.97 – 7.95 (m, 1H), 7.85 – 7.81 (m, 3H),
7.56 – 7.50 (m, 1H), 7.35 – 7.28 (m, 1H), 2.73 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 188.3,
168.7, 161.4 (d, J = 247.9 Hz), 135.8 (d, J = 7.1 Hz), 135.3, 132.9, 131.9, 129.3 (d, J = 7.6 Hz),
127.6, 126.82, 124.34 (d, J = 3.2 Hz), 123.39, 118.90 (d, J = 21.1 Hz), 117.80, 115.19 (d, J = 23.3
Hz), 39.15; HRMS: calcd for C16H12FNO4S [M+H]+ 334.0471, found 334.0545.
Data for (4c): yield 81 %; light yellow solid; m.p. 131–132 °C; 1H NMR (400 MHz, CDCl3) δ:
15.64 (s, 1H), 8.27 – 8.21 (m, 1H), 8.17 (d, J = 7.7 Hz, 1H), 8.05 (s, 1H), 8.00 – 7.92 (m, 1H),
7.87 – 7.79 (m, 2H), 7.60 (d, J = 7.9 Hz, 1H), 7.49 (t, J = 7.9 Hz, 1H), 2.72 (s, 3H); 13C NMR
(100 MHz, CDCl3) δ: 189.4, 169.66, 136.52, 136.31, 134.78, 133.93, 133.03, 132.84, 129.87,
129.08, 128.56, 127.86, 127.76, 124.44, 118.84, 40.21; HRMS: calcd for C16H12ClNO4S [M+H]+
350.0176, found 350.0249.
Data for (4d): yield 78 %; light yellow solid; m.p. 149–150 °C; 1H NMR (400 MHz, CDCl3) δ:
14

15.62 (s, 1H), 8.24 – 8.21 (m, 2H), 8.19 (s, 1H), 7.99 – 7.93 (m, 1H), 7.88 – 7.79 (m, 2H), 7.75 (d,
J = 8.2 Hz, 1H), 7.42 (t, J = 7.9 Hz, 1H), 2.72 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 189.3,
169.6, 136.7, 136.3, 135.7, 133.9, 133.0, 131.9, 130.1, 128.6, 128.2, 127.9, 124.4, 122.7, 118.8,
40.2; HRMS: calcd for C16H12BrNO4S [M+H]+ 393.9670, found 393.9743.
Data for (4e): yield 72 %; light yellow solid; m.p. 143–144 °C; 1H NMR (400 MHz, CDCl3) δ:
15.64 (s, 1H), 8.18 – 8.08 (m, 1H), 7.86 – 7.83 (m, 1H), 7.74 – 7.69 (m, 3H), 7.59 (s, 1H), 7.36 (t,
J = 8.0 Hz, 1H), 7.07 (dd, J = 8.3, 2.5 Hz, 1H), 3.82 (s, 3H), 2.63 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ: 190.9, 169.0, 159.5, 136.4, 136.2, 133.7, 132.9, 129.7, 128.7, 127.7, 124.3, 121.9, 119.6,
118.8, 113.6, 55.5, 40.0; HRMS: calcd for C17H15NO5S [M+H]+ 346.0671, found 346.0745.
Data for (4f): yield 74 %; yellow solid; m.p. 183–184 °C; 1H NMR (400 MHz, CDCl3) δ: 15.75 (s,
1H), 8.27 – 8.16 (m, 3H), 7.97 – 7.88 (m, 1H), 7.84 – 7.78 (m, 2H), 7.24 – 7.16 (m, 2H), 2.70 (s,
3H); 13C NMR (100 MHz, CDCl3) δ: 189.5, 169.2, 165.6 (d, J = 255.5 Hz), 136.2, 133.8, 133.0,
132.2 (d, J = 9.2 Hz), 131.2 (d, J = 3.1 Hz), 128.7, 127.8, 124.4, 118.7, 115.8 (d, J = 21.8 Hz),
99.9, 40.1; HRMS: calcd for C16H12FNO4S [M+H]+ 334.0471, found 334.0545.
Data for (4g): yield 86 %; yellow solid; m.p. 165–167 °C; 1H NMR (400 MHz, CDCl3) δ: 15.72
(s, 1H), 8.25 – 8.20 (m, 1H), 8.16 (d, J = 8.6 Hz, 2H), 7.98 – 7.93 (m, 1H), 7.87 – 7.79 (m, 2H),
7.52 (d, J = 8.6 Hz, 2H), 2.72 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 188.4, 168.6, 138.4, 135.2,
132.8, 132.2, 131.9, 129.9, 127.9, 127.6, 126.8, 123.4, 117.8, 39.1; HRMS: calcd for
C16H12ClNO4S [M+H]+ 350.0176, found 350.0249.
Data for (4h): yield 82 %; yellow solid; m.p. 205–207 °C; 1H NMR (400 MHz, CDCl3) δ: 15.69
(s, 1H), 8.24 – 8.17 (m, 1H), 8.05 (d, J = 8.5 Hz, 2H), 7.96 – 7.90 (m, 1H), 7.84 – 7.78 (m, 2H),
7.67 (d, J = 8.5 Hz, 2H), 2.70 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 189.6, 169.6, 136.3, 133.9,
133.7, 133.0, 131.9, 130.9, 128.6, 128.1, 127.8, 124.4, 118.8, 40.2; HRMS: calcd for
C16H12BrNO4S [M+H]+ 393.9670, found 393.9743.
Data for (4i): yield 78 %; yellow solid; m.p. 164–165 °C; 1H NMR (400 MHz, CDCl3) δ: 16.05 (s,
1H), 8.28 – 8.22 (m, 2H), 8.22 – 8.16 (m, 1H), 7.93-7.92 (m, 1H), 7.83 – 7.74 (m, 2H), 7.03 – 6.94
(m, 2H), 3.91 (s, 3H), 2.73 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 189.4, 168.7, 163.6, 136.1,
133.4, 132.9, 132.0, 129.0, 127.7, 127.5, 124.2, 118.6, 113.9, 55.6, 40.0; HRMS: calcd for
C17H15NO5S [M+H]+ 346.0671, found 346.0745.
5.4. Methyl (1, 1-dioxido-3-oxo-1, 2-benzisothiazol-2(3H)-yl) acetate (5):
A mixture of 1 (41.0 g, 0.2 mol) and methyl chloroformate (21.6 g, 0.2 mol) in DMF (300 ml)
was taken in a round bottom flask and was heated at 138 °C for 2 h. Contents were then cooled to
room temperature and poured over ice cooled water (1000 ml) resulting in the formation of a
white solid, which was filtered and washed with cold water. The solid was dried and recrystallized
from methanol to get the product 5 as a white solid (48.1 g, yield: 94.3%).
5.5. Methyl 4-hydroxy-2H-1, 2-benzothiazine-3-carboxylate 1, 1-dioxide (6):
Sodium metal (6.9 g; 300 mmol) and dry methanol (400 ml) was allowed to reflux until all the
metal dissolved. To this solution, 5 (30.2 g; 118.4 mmol) was added in a single portion.
Temperature of the mixture was maintained at 55 °C for 30 min till the completion of reaction.
The contents were then cooled to 5 °C and poured over an ice-water mixture. Hydrochloric acid (2
N) was added to the mixture till the pH became approximately 3. The precipitates formed were
filtered and dried at 70 °C to get the product 6 as a white solid (26.4 g, yield: 87 %).
5.6. 2H-1, 2-benzothiazin-4(3H)-one 1, 1-dioxide (7):
Compound 6 (25.5 g, 0.1 mol) was added to concentrated hydrochloric acid (300 mL) and
15

refluxed for 8 h. The crude material was then poured into ice-water mixture and the precipitate
was collected by suction filtration, washed with cold water and dried to give the desired product 7
as a white solid (9.4 g, yield: 48 %).
5.7. 2-Methyl-2H-1, 2-Benzothiazin-4(3H)-one 1, 1-dioxide (8):
A mixture of 7 (2.0 g, 10 mmol), cesium carbonate (3.6 g, 11 mmol) and iodomethane (1.4 g,
10 mmol) in DMF (20 ml) was taken in a round bottom flask and was stirred at room temperature
until the starting material had disappeared. The mixture was poured into water and extracted with
ethyl acetate. The combined organic phase was dried with anhydrous sodium sulfate, filtered and
removed by rotary evaporation to yield brown viscous oil. The oil was scratched from ethyl
acetate and petroleum ether (1/10 by volumn) to give desired product 8 as a light yellow solid (1.4
g, yield: 66 %).
5.8. General procedure for compounds (4j-4w):
A solution of compound 8 (1.1 g, 5 mmol) in DMF (10 mL) was added to sodium hydride (0.26
g, 7.5 mmol of a 60 % suspension in mineral oil which had been washed with benzene by
decantation) at 0 °C. After stirring for 10 min, 4-nitrobenzoyl chloride was added during 20 min.
The solution was stirred at 25 °C for 1 h and then evaporated. The residue was suspended in water
and extracted with ethyl acetate. The combined organic phase was dried with anhydrous sodium
sulfate, filtered and removed by rotary evaporation to yield 9a as brown viscous oil, which was
used in the next step without further purification.
A solution of compound 9a (1.0 g, 2.7 mmol) in dichloromethane (10 mL) was added to
triethylamine (0.4 g, 4 mmol), 18-Crown-6 (71 mg, 0.3 mmol) and potassium cyanide (91 mg,
1.4mmol). The mixture was stirred at 25 °C for 48 h. The mixture was poured into water and
extracted with dichloromethane. The combined organic phase was dried with anhydrous sodium
sulfate, filtered and removed by rotary evaporation. The residue was scratched from ethyl acetate
and ethanol (1/1 by volumn) to give desired product to 4j as a yellow solid (734 mg, yield: 41 %).
The rest of compounds were prepared by the similar procedure to 4j.
Data for (4j): yield 41 %; yellow solid; m.p. 196–197 °C; 1H NMR (400 MHz, CDCl3) δ: 15.45 (s,
1H), 8.42 – 8.36 (m, 2H), 8.35 – 8.29 (m, 2H), 8.27 – 8.18 (m, 1H), 7.98–7.95 (m, 1H), 7.91 –
7.82 (m, 2H), 2.70 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 188.3, 170.8, 149.9, 140.2, 136.3,
134.3, 133.2, 130.5, 128.3, 128.0, 124.6, 123.7, 119.1, 40.4; HRMS: calcd for C16H12N2O6S
[M+H]+ 361.0416, found 361.0492.
Data for (4k): yield 32 %; light yellow solid; m.p. 223–225 °C; 1H NMR (400 MHz, CDCl3) δ:
15.47 (s, 1H), 8.38 – 8.30 (m, 2H), 8.27 – 8.20 (m, 1H), 8.16 – 8.10 (m, 2H), 8.00 – 7.94 (m, 1H),
7.89 – 7.82 (m, 2H), 3.15 (s, 3H), 2.70 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 187.7, 169.6,
142.7, 138.5, 135.3, 133.3, 132.2, 129.2, 127.3, 126.9, 126.5, 123.6, 118.0, 43.3, 39.4; HRMS:
calcd for C17H15NO6S2 [M+H]+ 394.0341, found 394.0416.
Data for (4l): yield 43 %; light yellow solid; m.p. 209–210 °C; 1H NMR (400 MHz, CDCl3) δ:
14.89 (s, 1H), 8.25 – 8.20 (m, 1H), 7.95 – 7.90 (m, 1H), 7.87 – 7.82 (m, 2H), 7.64 (d, J = 7.9 Hz,
2H), 7.39 (t, J = 7.9 Hz, 1H), 2.68 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 191.8, 168.7, 136.4,
136.4, 134.1, 133.0, 132.5, 129.6, 128.4, 128.2, 127.8, 127.5, 125.2, 124.5, 119.2, 40.0; HRMS:
calcd for C16H11Cl2NO4S [M+H]+ 383.9786, found 383.9861.
1
Data for (4m): yield 41 %; light yellow solid; m.p. 184–185 °C; H NMR (400 MHz, CDCl3) δ:
14.88 (s, 1H), 8.22 (dd, J = 5.9, 3.2 Hz, 1H), 7.94 (dd, J = 5.9, 3.0 Hz, 1H), 7.88 – 7.80 (m, 2H),
7.69 (s, 1H), 7.46 (s, 2H), 2.69 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 191.1, 168.9, 136.5, 135.8,
16

134.2, 133.0, 132.8, 131.9, 131.4, 129.9, 129.5, 128.2, 127.8, 124.6, 119.3, 40.1; HRMS: calcd for
C16H11Cl2NO4S [M+H]+ 383.9786, found 383.9861.
Data for (4n): yield 38 %; yellow solid; m.p. 212–214 °C; 1H NMR (400 MHz, CDCl3) δ: 15.55
(s, 1H), 8.22 – 8.18 (m, 1H), 8.17 (d, J = 2.0 Hz, 1H), 8.12 (dd, J = 8.4, 2.0 Hz, 1H), 7.93 (dt, J =
5.3, 3.0 Hz, 1H), 7.84 – 7.79 (m, 2H), 7.60 (d, J = 8.4 Hz, 1H), 2.71 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ: 188.1, 169.9, 137.5, 136.2, 134.6, 134.1, 133.3, 133.1, 131.1, 130.7, 128.8, 128.5, 127.9,
124.5, 118.8, 40.3; HRMS: calcd for C16H11Cl2NO4S [M+H]+ 383.9786, found 383.9861.
Data for (4o): yield 43 %; yellow solid; m.p. 221–222 °C; 1H NMR (400 MHz, CDCl3) δ: 15.47
(s, 1H), 8.25 – 8.19 (m, 1H), 8.03 (d, J = 1.8 Hz, 2H), 7.99 – 7.94 (m, 1H), 7.90 – 7.81 (m, 2H),
7.60 (t, J = 1.8 Hz, 1H), 2.74 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 186.9, 169.0, 136.4, 135.3,
134.4, 133.1, 132.1, 131.5, 127.3, 126.9, 126.6, 123.6, 117.8, 39.3; HRMS: calcd for
C16H11Cl2NO4S [M+H]+ 383.9786, found 383.9861.
1
Data for (4p): yield 32 %; light yellow solid; m.p. 158–160 °C; H NMR (400 MHz, CDCl3) δ:
14.92 (s, 1H), 8.23 (dd, J = 5.9, 3.1 Hz, 1H), 7.96 – 7.90 (m, 1H), 7.88 – 7.81 (m, 2H), 7.73 (d, J =
8.3 Hz, 1H), 7.56 (d, J = 1.9 Hz, 1H), 7.43 (dd, J = 8.3, 2.0 Hz, 1H), 2.67 (s, 3H); 13C NMR (100
MHz, CDCl3) δ: 191.4, 168.7, 137.6, 136.4, 134.1, 133.0, 132.7, 132.4, 131.5, 130.3, 128.3, 127.8,
127.1, 124.5, 119.3, 40.0; HRMS: calcd for C16H11Cl2NO4S [M+H]+ 383.9786, found 383.9861.
Data for (4q): yield 33 %; light yellow solid; m.p. 174–175 °C; 1H NMR (400 MHz, CDCl3) δ:
14.97 (s, 1H), 8.27 – 8.18 (m, 1H), 7.97 – 7.91 (m, 1H), 7.88 – 7.78 (m, 3H), 7.29 – 7.26 (m, 1H),
7.16 (td, J = 8.4, 2.3 Hz, 1H), 2.66 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 191.5, 168.5, 163.6 (d,
J = 255.5 Hz), 136.4, 134.0, 133.0, 133.0 (d, J = 10.5 Hz), 132.4 (d, J = 9.5 Hz), 130.5 (d, J = 3.3
Hz), 128.3, 127.8, 124.5, 119.3, 118.0 (d, J = 25.0 Hz), 114.2 (d, J = 21.4 Hz), 39.9; HRMS: calcd
for C16H11ClFNO4S [M+H]+ 368.0081, found 368.0157.
1
Data for (4r): yield 27 %; light yellow solid; m.p. 171–172 °C; H NMR (400 MHz, CDCl3) δ:
14.89 (s, 1H), 8.20 (dd, J = 5.8, 3.2 Hz, 1H), 7.91 (dd, J = 5.8, 3.2 Hz, 1H), 7.84 – 7.79 (m, 2H),
7.69 (d, J = 1.7 Hz, 1H), 7.63 (d, J = 8.3 Hz, 1H), 7.55 (dd, J = 8.3, 1.7 Hz, 1H), 2.64 (s, 3H); 13
C
NMR (100 MHz, CDCl3) δ: 190.4, 167.6, 135.4, 133.1, 132.1, 131.9, 131.3, 130.5, 128.9, 127.2,
126.8, 124.5, 123.5, 118.2, 38.9; HRMS: calcd for C16H11BrClNO4S [M+H]+ 427.9281, found
427.9355.
1
Data for (4s): yield 21 %; light yellow solid; m.p. 159–160 °C; H NMR (400 MHz, CDCl3) δ:
14.86 (s, 1H), 8.23 – 8.16 (m, 1H), 7.92 – 7.89 (m, 1H), 7.85 – 7.78 (m, 2H), 7.71 (d, J = 1.9 Hz,
1H), 7.69 (d, J = 8.3 Hz, 1H), 7.45 (dd, J = 8.3, 2.0 Hz, 1H), 2.65 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ: 192.2, 168.7, 137.6, 136.5, 134.7, 134.1, 133.3, 133.0, 131.5, 128.2, 127.8, 127.6, 124.5,
120.2, 119.1, 39.9; HRMS: calcd for C16H11BrClNO4S [M+H]+ 427.9281, found 427.9355.
Data for (4t): yield 29 %; light yellow solid; m.p. 134–136 °C; 1H NMR (400 MHz, CDCl3) δ:
14.87 (s, 1H), 8.26 – 8.18 (m, 1H), 7.96 – 7.88 (m, 2H), 7.87 – 7.80 (m, 2H), 7.63 (s, 2H), 2.68 (s,
3H); 13C NMR (100 MHz, CDCl3) δ: 192.3, 168.6, 136.4, 136.0, 135.1, 134.1, 133.0, 131.6, 130.5,
128.2, 127.8, 125.6, 125.2, 124.5, 119.0, 40.0; HRMS: calcd for C16H11Br2NO4S [M+H]+
471.8776, found 471.8849.
Data for (4u): yield 36 %; light yellow solid; m.p. 202–203 °C; 1H NMR (400 MHz, CDCl3) δ:
14.69 (s, 1H), 8.39 (d, J = 2.0 Hz, 1H), 8.27 (dd, J = 8.5, 2.1 Hz, 1H), 8.24 – 8.18 (m, 1H), 7.95 –
7.88 (m, 2H), 7.87 – 7.80 (m, 2H), 2.65 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 190.4, 169.3,
149.2, 140.0, 136.4, 134.5, 133.2, 132.7, 131.3, 127.9, 125.5, 124.8, 121.8, 119.2, 40.3; HRMS:
calcd for C16H11ClN2O6S [M+H]+ 395.0026, found 395.0100.
17

1
Data for (4v): yield 32 %; light yellow solid; m.p. 175–177 °C; H NMR (400 MHz, CDCl3) δ:
14.81 (s, 1H), 8.27 – 8.19 (m, 1H), 7.98 – 7.91 (m, 1H), 7.91 – 7.83 (m, 3H), 7.80 (s, 1H), 7.70 (d,
J = 7.9 Hz, 1H), 2.68 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 191.1, 169.1, 137.7, 136.5, 134.3,
133.1, 132.0, 130.9, 128.1, 127.9, 127.4 (q, J = 4.2 Hz), 124.6 (s), 123.7 (dd, J = 7.2, 3.6 Hz),
119.3, 40.1; HRMS: calcd for C17H11ClF3NO4S [M+H]+ 418.0049, found 418.0123.
1
Data for (4w): yield 40 %; light yellow solid; m.p. 224–226 °C; H NMR (400 MHz, CDCl3) δ:
14.65 (s, 1H), 8.19 – 8.11 (m, 1H), 8.04 (s, 1H), 7.91 (d, J = 7.9 Hz, 1H), 7.85 (t, J = 7.3 Hz, 2H),
7.78 (dd, J = 8.8, 5.0 Hz, 2H), 3.08 (s, 3H), 2.59 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 189.7,
168.2, 142.6, 138.3, 135.3, 133.4, 132.2, 131.6, 130.4, 128.3, 126.9, 126.9, 124.5, 123.7, 118.2,
43.4, 39.3; HRMS: calcd for C17H14ClNO6S2 [M+H]+ 427.9951, found 428.0027.
5.9. Methyl 2-(methylsulfonamido)benzoate( 11):
To a stirred solution of methyl 2-aminobenzoate (25.0 g, 165.6 mmol) in pyridine (200 mL) at
0 °C, methane sulfonyl chloride (13 mL, 168 mmol) was added drop wise and the mixture stirred
at 25 °C for 3 h. After completion, the reaction was quenched with ice cold water and extracted
with ethyl acetate (3 x 200 mL). The organic layer was washed with water (50 mL), brine (50 mL),
dried with anhydrous sodium sulfate and concentrated. The resulting crude product eluted at ethyl
acetate in hexane (1/4 by volumn). The fractions with product were concentrated to obtain methyl
2-(methylsulfonamido) benzoate as white solid (37.0 g, yield: 98 %).
5.10.
Methyl 2-(N-methylmethylsulfonamido)benzoate (12):
To a solution of methyl 2-(methylsulfonamido) benzoate (37.0 g, 162 mmol) in DMF (300 mL),
cesium carbonate (79.0 g, 242.4 mmol) was added slowly and stirred for 12 h. To this mixture,
excess methyl iodide (12 mL, 193.9 mmol) was added and the mixture stirred at 25 °C for 16 h.
After completion, the mixture was quenched with saturated ammonium chloride solution (100
mL). The aqueous layer was extracted with ethyl acetate (3 x 300 mL) and the combined organic
layer was washed with water (100 mL), brine (50 mL), dried over anhydrous sodium sulfate and
concentrated to obtain methyl 2-(N-methylmethylsulfonamido)benzoate as white solid (28.0 g,
71 %).
5.11.
2, 2-Dioxo-1-methyl-2, 1-benzothiazin-4(3H)-one (13):
To a suspension of benzene washed sodium hydride (2.3 g; 96 mmol) in dry DMF (30 mL), a
solution of 2-(N-methylmethylsulfonamido) benzoate (11.7 g; 48 mmol) in dry DMF (70 mL) was
added and stirred at room temperature for 1.5 h. After completion of the reaction (as indicated by
TLC), the contents were poured into cold hydrochloric acid (2 N) to get the precipitates, which
were dried at room temperature to get 2, 2-dioxo-1-methyl-2, 1-benzothiazin-4(3H)-one as white
solid (9.1 g, 90 %).
5.12.
General procedure for compounds (15a-15j):
A solution of compound 13 (1.1 g, 5 mmol) in DMF (10 mL) was added to sodium hydride (0.3
g, 7.5 mmol of a 60% suspension in mineral oil which had been washed with benzene by
decantation) at 0 °C. After stirring for 10 min, benzoyl chloride (1.4 g, 10 mmol) was added
during 20 min. The solution was stirred at 25 °C for 1 h and then evaporated. The residue was
suspended in water and extracted with ethyl acetate. The combined organic phase was dried with
anhydrous sodium sulfate, filtered and removed by rotary evaporation to yield 14a as brown
viscous oil, which was used in the next step without further purification.
A solution of compound 14a (0.9 g, 2.8 mmol) in dichloromethane (10 mL) was added to
triethylamine (0.4 g, 4 mmol), 18-Crown-6 (71 mg, 0.3 mmol) and potassium cyanide (91 mg,
18

1.4mmol). The mixture was stirred at 25 °C for 48 h. The mixture was poured into water and
extracted with dichloromethane. The combined organic phase was dried with anhydrous sodium
sulfate, filtered and removed by rotary evaporation. The residue was scratched from ethyl acetate
and ethanol (1/1 by volumn) to give desired product 15a as yellow solid (572 mg, yield: 36 %).
The rest of compounds were prepared by the similar procedure to 15a.
Data for (15a): yield 36 %; light yellow solid; m.p. 208–210 °C; 1H NMR (400 MHz, CDCl3) δ:
8.19 (dd, J = 8.0, 1.4 Hz, 1H), 7.86 (dd, J = 5.2, 3.3 Hz, 2H), 7.73 – 7.67 (m, 1H), 7.65 – 7.59 (m,
1H), 7.53 (dd, J = 10.4, 4.7 Hz, 2H), 7.38 – 7.31 (m, 1H), 7.23 (d, J = 8.3 Hz, 1H), 3.39 (s, 3H);
13C NMR (100 MHz, CDCl3) δ: 193.2, 177.4, 142.1, 137.2, 135.6, 132.5, 128.2, 128.1, 128.1,
123.9 , 120.3, 117.9, 115.2, 32.1; HRMS: calcd for C16H13NO4S [M+H]+ 316.0565, found
316.0640.
Data for (15b): yield 33 %; light yellow solid; m.p. 138–140 °C; 1H NMR (400 MHz, CDCl3) δ:
8.19 (dd, J = 7.9, 1.1 Hz, 1H), 7.96 – 7.88 (m, 2H), 7.76 – 7.68 (m, 1H), 7.36 (t, J = 7.6 Hz, 1H),
7.22 (dd, J = 17.8, 8.9 Hz, 3H), 3.40 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 191.8, 177.2, 165.4
(d, J = 254.1 Hz), 141.9, 135.7, 133.4 (d, J = 3.0 Hz), 131.1 (d, J = 9.4 Hz), 128.1, 124.1, 120.2,
117.9, 115.4 (d, J = 22.0 Hz), 115.1, 32.2; HRMS: calcd for C16H12FNO4S [M+H]+ 334.0471,
found 334.0545.
Data for (15c): yield 38 %; light yellow solid; m.p. 170–172 °C; 1H NMR (400 MHz, CDCl3) δ:
8.19 (d, J = 7.4 Hz, 1H), 7.82 (d, J = 8.4 Hz, 2H), 7.72 (t, J = 7.3 Hz, 1H), 7.50 (d, J = 8.4 Hz, 2H),
7.36 (t, J = 7.6 Hz, 1H), 7.24 (d, J = 8.3 Hz, 1H), 3.40 (s, 3H); 13C NMR (100 MHz, CDCl3) δ:
191.9, 177.2, 142.0, 138.9, 135.8, 135.6, 129.8, 128.5, 128.2, 124.1, 120.1, 117.9, 115.1, 32.2;
HRMS: calcd for C16H12ClNO4S [M+H]+ 350.0176, found 350.0249.
Data for (15d): yield 30 %; light yellow solid; m.p. 178–180 °C; 1H NMR (400 MHz, CDCl3) δ:
8.18 (dd, J = 8.0, 1.2 Hz, 1H), 7.73 (t, J = 6.4 Hz, 3H), 7.65 (d, J = 8.6 Hz, 2H), 7.35 (t, J = 7.6 Hz,
1H), 7.23 (d, J = 8.3 Hz, 1H), 3.39 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 191.1, 176.2, 141.0,
134.9, 134.8, 130.4, 128.8, 127.1, 126.5, 123.0, 119.0, 116.9, 114.1, 31.1; HRMS: calcd for
C16H12BrNO4S [M+H]+ 393.9670, found 393.9743.
Data for (15e): yield 24 %; light yellow solid; m.p. 135–136 °C; 1H NMR (400 MHz, CDCl3) δ:
8.14 (dd, J = 8.0, 1.0 Hz, 1H), 7.92 (d, J = 8.8 Hz, 2H), 7.72 – 7.63 (m, 1H), 7.32 (t, J = 7.6 Hz,
1H), 7.21 (d, J = 8.2 Hz, 1H), 7.00 (d, J = 8.8 Hz, 2H), 3.88 (s, 3H), 3.37 (s, 3H); 13C NMR (100
MHz, CDCl3) δ: 191.5, 177.4, 163.5, 141.9, 135.3, 131.2, 129.2, 128.0, 124.1, 120.8, 118.1, 114.9,
113.5, 55.5, 32.5; HRMS: calcd for C17H15NO5S [M+H]+ 346.0671, found 346.0745.
1
Data for (15f): yield 39 %; yellow solid; m.p. 162–164 °C; H NMR (400 MHz, CDCl3) δ: 8.36
(d, J = 8.6 Hz, 2H), 8.22 (d, J = 7.9 Hz, 1H), 7.96 (d, J = 8.6 Hz, 2H), 7.76 (t, J = 7.3 Hz, 1H),
7.38 (t, J = 7.6 Hz, 1H), 7.26 (d, J = 8.3 Hz, 1H), 3.40 (s, 3H); 13C NMR (100 MHz, CDCl3) δ:
191.6, 176.9, 149.6, 142.9, 142.2, 136.3, 129.0, 128.3, 124.2, 123.4, 119.4, 117.9, 115.1, 31.9;
HRMS: calcd for C16H12N2O6S [M+H]+ 361.0416, found 361.0492.
Data for (15g): yield 27 %; light yellow solid; m.p. 195–197 °C; 1H NMR (400 MHz, CDCl3) δ:
8.19 (d, J = 7.9 Hz, 1H), 8.07 (d, J = 8.3 Hz, 2H), 7.97 (d, J = 8.3 Hz, 2H), 7.76 – 7.69 (m, 1H),
7.35 (t, J = 7.6 Hz, 1H), 7.23 (d, J = 8.3 Hz, 1H), 3.38 (s, 3H), 3.11 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ: 191.9, 177.1, 143.3, 142.2, 136.2, 128.9, 128.3, 127.2, 124.2, 119.5, 117.9, 115.1, 44.4,
32.0; HRMS: calcd for C17H15NO6S2 [M+H]+ 394.0341, found 394.0416.
Data for (15h): yield 31 %; light yellow solid; m.p. 161–163 °C; 1H NMR (400 MHz, CDCl3) δ:
8.21 (dd, J = 8.0, 1.2 Hz, 1H), 7.75 – 7.66 (m, 1H), 7.50 (d, J = 1.7 Hz, 1H), 7.43 (d, J = 8.2 Hz,
19

1H), 7.39 – 7.29 (m, 2H), 7.20 (d, J = 8.3 Hz, 1H), 3.39 (s, 3H); 13C NMR (100 MHz, CDCl3) δ:
190.9, 176.6, 142.6, 137.1, 136.3, 135.1, 131.5, 129.8, 128.8, 128.3, 127.0, 123.8, 118.9, 117.6,
115.1, 31.7; HRMS: calcd for C16H11Cl2NO4S [M+H]+ 383.9786, found 383.9861.
Data for (15i): yield 32 %; light yellow solid; m.p. 209–211 °C; 1H NMR (400 MHz, DMSO) δ:
8.03 (d, J = 7.9 Hz, 1H), 7.78 (t, J = 7.2 Hz, 1H), 7.64 – 7.54 (m, 2H), 7.44 (d, J = 8.3 Hz, 1H),
7.38 – 7.31 (m, 2H), 3.33 (s, 3H); 13C NMR (100 MHz, DMSO) δ: 187.3, 172.8, 162.9 (d, J =
250.4 Hz), 142.5, 136.0, 135.4 (d, J = 2.6 Hz), 131.6 (d, J = 11.2 Hz), 131.0 (d, J = 9.6 Hz), 127.9,
124.1, 120.2, 118.9, 117.5 (d, J = 25.4 Hz), 115.5, 114.8 (d, J = 21.7 Hz), 32.1; HRMS: calcd for
C16H11ClFNO4S [M+H]+ 368.0081, found 368.0157.
1
Data for (15j): yield 34 %; light yellow solid; m.p. 190–192 °C; H NMR (400 MHz, CDCl3) δ:
8.24 (dd, J = 8.0, 1.5 Hz, 1H), 7.78 – 7.71 (m, 1H), 7.69 (d, J = 1.7 Hz, 1H), 7.56 (dd, J = 8.2, 1.8
Hz, 1H), 7.42 – 7.32 (m, 1H), 7.23 (d, J = 8.3 Hz, 1H), 3.43 (s, 1H); 13C NMR (100 MHz, CDCl3)
δ: 189.9, 175.6, 141.5, 135.3, 134.5, 131.5, 130.5, 128.9, 127.8, 127.3, 123.9, 122.8, 117.9, 116.5,
113.9, 30.6; HRMS: calcd for C16H11BrClNO4S [M+H]+ 427.9281, found 427.9355.
Acknowledgements
This work was supported by Special Fund for Agro-scientific Research in the Public Interest
(grant No. 201403030). The authors are very grateful to Prof. Yang GuangFu, Yang WenChao
and Wu Lei (Key Laboratory of Pesticide and Chemical Biology, College of Chemistry, Central
China Normal University, Wuhan, China) for providing the preparation of HPPD and the
evaluation of HPPD Inhibitors.
References and notes
1. Ryle, M. J.; Hausinger, R. P. Curr. Opin. Chem. Biol. 2002, 6, 193.
2. Neidig, M. L.; Decker, A.; Choroba, O. W.; Huang, F. l.; Kavana, M.; Moran, G. R.; Spencer,
J. B.; Solomon, E. I. Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 12966−12973.
3. He, P.; Moran, G. R. Curr. Opin. Chem. Biol. 2009, 13, 443−450.
4. Kovaleva, E.G. and Lipscomb, J. D. Nat. Chem. Biol. 2008, 4,186–193.
5. Brownlee, J.M.; Johnson-Winters, K.; Harrison, D. H.T. and Moran, G. R. Biochemistry. 2004,
43, 6370–6377.
6. Raspail, C.; Graindorge, M.; Moreau, Y.; Crouzy, S.; Lefèbvre, B.; Robin, A. Y. et al. J. Biol.
Chem. 2011, 286, 26061–26070.
7. Wu, C. S.; Huang, J. L.; Sun, Y. S. and Yang, D. Y. J. Med. Chem. 2002, 45, 2222–2228.
8. Norris, S. R.; Barrette, T. R. and DellaPenna, D. Plant Cell. 1995, 7, 2139–2149.
9. Purpero, V. M.; Moran, G. R. Biochemistry. 2006, 45, 6044−6055.
10. Yang, C.; Pflugrath, J. W.; Camper, D. L.; Foster, M. L.; Pernich, D. J.; Walsh, T. A.
Biochemistry. 2004, 43, 10414−10423.
11. Borowski, T.; Bassan, A.; Siegbahn, P. E. Biochemistry. 2004, 43, 12331−12342.
12. López-Ramos, M. and Perruccio, F. J. Chem. Inf. Model. 2010, 50, 801.
13. Beaudegnies, R.; Edmunds, A. J. F.; Fraser, T. E. M.; Hall, R. G.; Hawkes, T. R.; Mitchell, G.;
Schaetzer, J.; Wendeborn, S.; Wibley, J. Bioorg. Med. Chem. 2009, 17, 4134–4152.
14. Witschel, M. Bioorg. Med. Chem. 2009, 17, 4221.
15. Mitchell, G.; Bartlett, D. W.; Fraser, T. E. M.; Hawkes, T. R.; Holt, D. C.; Townson, J. K.;
Wichert, R. A. Pest Manag. Sci. 2001, 57, 120.
16. van Almsick, A.; Benet-Buchholz, J.; Olenik, B.; Willms, L. Bayer Crop Sci. J. 2009, 62, 5.
17. Ahrens, H.; Lange, G.; Müller, T.; Rosinger, C.; Wilms, L.; van Almsick, A. Angew. Chem.,
20

Int. Ed. 2013, 52, 9388.
18. van Almsick, A. Outlooks Pest Manag. 2009, 20, 27–30.
19. Lin, Y. L.; Wu, C. S.; Lin, S. W.; Yang, D. Y. Bioorg. Med. Chem. Lett. 2000, 10, 843−845.
20. Lee, D.L.; Prisbylla, M. P. Cromartie, T. H.; Dagarin, D. P.; Howard, S. W.; Provan, W. M. et
al. Weed Sci. 1997, 45, 601–609.
21. Ryan, K. P.; Maganbhai, P. K.; Paul, S. T.; Todd, S. B. and Edmund, T. A. WO Patent
2011031658 A1, 2011.
22. Lomabardino, J. G.; Wiseman, E. H.; McLamore, W. M. J. Med. Chem. 1971, 14, 1171–1175.
23. Türck, D.; Busch, U.; Heinzel, G.; Narjes, H.; Nehmiz, G. Clin. Drug Invest. 1995, 9,
270–276.
24. Engelhardt, G.; Homma, D.; Schlegel, K. et al. Inflamm Res. 1995, 44, 422–433.
25. Myung, P. S.; Soon, K. K. Bull. Korean Chem. Soc. 2000, 21, 1249–1250.
26. Caruso, I.; Montrone, F.; Boari, L. Adv Ther. 1994, 11, 132–138.
27. Soler, J. E. US Patent 45634527, 1986.
28. Giuseppe, M.; Arnaldo, F.; Patrizia, T. US Patent 466878426, 1987.
29. Ikeda, T.; Kakegawa, H.; Miyataka, H.; Matsumoto, H.; Satoht, T. Bio. Med. Chem. Lett.
1992, 2, 709–714.
30. Krapcho, J.; Turk, C. F. US Patent 3929783, 1975.
31. Constantine, J. W. Nature. 1967, 214, 1084–1086.
32. Barreca, M. L.; Manfroni, G.; Leyssen, P.; Winquist, J.; Kaushik-Basu, N.; Paeshuyse, J.;
Krishnan, R.; Iraci, N.; Sabatini, S.; Tabarrini, O.; Basu, A.; Danielson, U. H.; Neyts, J.
Cecchetti, V. J. Med. Chem. 2013, 56, 2270–2282.
33. Aslam, S.; Ahmad, M.; Athar, M. M.; Ashfaq, U. A.; Gardiner, J. M.; Montero, C.; Detorio,
M.; Parvez, M.; Schinazi, R. F. Med. Chem. Res. 2014, 23, 2930–2946.
34. Liu, B.; Xie, L. G.; Xu, X. H.; Li, Y. H. Chinese J. Org. Chem. 2011, 31, 2067–2073.
35. Although the scaffold of compound I was reported as potential 11β-hydroxysteroid
dehydrogenase 1 inhibitor, any biological data in pesticide formulation were not disclosed.
(Kim, S. H.; Ramu, R.; Kwon, S. K.; Lee, S. H.; Kim, K. Y.; , Ahn, L. H. et al. Bioorg. Med.
Chem. Lett. 2010, 20, 1065–1069.)
36. Ogawa, H.; Yamada, I.; Arai, K.; Hirase, K.; Moriyasu, K.; Schneider, C. et al. Pest Manag.
Sci. 2001, 57, 33–40.
37. Wang, B. L.; Duggleby, R. G.; Li, Z. M.; Wang, J. G.; Li, Y. H.; Wang, S. H. et al. Pest
Manag. Sci. 2005, 61, 407–412.
38. Zhang, M.; Xu, X. H.; Cui, Y.; Xie, L. G. and Kong, C. H. Pest Manag. Sci. 2012, 68,
1512–1522.
39. Wang, D. W.; Lin, H. Y.; Cao, R. J.; Chen, T.; Wu, F. X.; Hao, G. F.; Chen, Q.; Yang, W. C.;
Yang, G. F. J. Agric. Food Chem. 2015, 63, 5587–5596.
40. Wang, D. W.; Lin, H. Y.; Cao, R. J.; Yang, S. G.; Chen, Q.; Hao, G. F.; Yang, W. C.; Yang,
G. F. J. Agric. Food Chem. 2014, 62, 11786−11796.
41. Wang, D. W.; Lin, H. Y.; Cao, R. J.; Ming, Z. Z.; Chen, T.; Hao, G. F.; Yang, W. C.; Yang, G.
F. Pest Manag. Sci. 2015, 71, 1122−1132.
42. Xu, Y. L.; Lin, H. Y.; Ruan, X.; Yang, S. G.; Hao, G. F.; Yang, W. C.; Yang, G. F. Eur. J. Med.
Chem. 2015, 92, 427−438.
43. Xu, Y. L.; Lin, H. Y.; Cao, R. J.; Ming, Z. Z.; Yang, W. C.; Yang, G. F. Bioorg. Med. Chem.
21

2014, 22, 5194−5211.
44. Wang, D. W.; Lin, H. Y.; Cao, R. J.; Yang, S. G.; Chen, T.; He, B.; Chen, Q.; Yang, W. C.;
Yang, G. F. Acta Chimica Sinica. 2015, 73, 29−35.
45. Schmidt, S. R. M ller, C. R.; Kress, W. Eur. J. Biochem. 1995, 228, 425−430.
46. Liu, X. H.; Shi, Y. X.; Ma, Y.; He, G. R.; Dong, W. L.; Zhang, C.Y.; Wang, B. L.; Wang, S.
H.; Li, B. J.; Li, Z. M. Chem. Biol. Drug Des. 2009, 73, 320–327.
47. Liu, X. H.; Shi, Y. X.; Ma, Y.; Zhang, C. Y.; Dong, W. L.; Li, P.; Wang, B. L.; Li, B. J.; Li, Z.
M. Eur. J. Med. Chem. 2009, 44, 2782–2786.
48. Kim, S. H.; Kwon, S.W.; Chu, S.Y.; Lee, J. H.; Narsaiah, B.; Kim, C. H.; Kim, K. Y.; Ahn, J.
H. et al. Chem. Pharm. Bull. 2011, 59, 46–52.
49. Brooke, E. W.; Davies, S. G.; Mulvaney, A. W.; Okada, M.; Pompeo, F.; Sim, E.; Vickers, R.
J.; Westwood, I. M. Bioorg. Med. Chem. Lett. 2003, 13, 2527–2530.
50. Coppo, F. T.; Fawzi, M. M. J. Heterocyclic Chem. 1998, 35, 983–987.
51. Muhammad, S.; Islam Ullah, K.; Muhammad Nadeem, A.; Waseeq Ahmad, S. Asian J. Chem.
2011, 23, 2101–2105.
52. Muhammad, S.; Muhammad, Z. U. R.; Islam Ullah, K.; Muhammad Nadeem, A.; Siraj
Ahmed. K. J. Chil. Chem. Soc. 2011, 56, 527–531.
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