Facile synthesis of 4H-1,2,4-benzothiadiazine-1,1-dioxides

Article abstract of DOI:10.1080/00397911.2010.494815

o-Bromoarylsulfonylated amidines prepared either by acylation of amidine with o-bromoarylsulfonyl chloride or through the reaction of o-bromoarylsulfoamide with lactime ether underwent Cu(I)-catalyzed intramolecular cyclization to give 4H-1,2,4-benzothiadiazine-1,1-dioxides in good yield. By varying substituents on arylsulfonyl moieties, amidines, and lactime ethers, a small library of structurally diverse 4H-1,2,4- benzothiadiazine-1,1-dioxide derivatives was prepared.

Full text of DOI:10.1080/00397911.2010.494815

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Facile Synthesis of 4H-1,2,4-
Benzothiadiazine-1,1-dioxides
Artem Cherepakha a , Vladimir O. Kovtunenko a , Andrey Tolmachev
a b , Oleg Lukin a b & Konstantin G. Nazarenko c
a National Taras Shevchenko University, ChemBioCenter , Kiev,
Ukraine
b Enamine Ltd. , Kiev, Ukraine
c Institute of Organic Chemistry, National Academy of Sciences of
Ukraine , Kiev, Ukraine
Published online: 02 May 2011.
To cite this article: Artem Cherepakha , Vladimir O. Kovtunenko , Andrey Tolmachev , Oleg Lukin &
Konstantin G. Nazarenko (2011) Facile Synthesis of 4H-1,2,4-Benzothiadiazine-1,1-dioxides, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
41:13, 1977-1989, DOI: 10.1080/00397911.2010.494815
To link to this article: http://dx.doi.org/10.1080/00397911.2010.494815
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Synthetic Communications1, 41: 1977–1989, 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.494815
FACILE SYNTHESIS OF 4H-1,2,4-BENZOTHIADIAZINE-
1,1-DIOXIDES
Artem Cherepakha,1 Vladimir O. Kovtunenko,1
Andrey Tolmachev,1,2 Oleg Lukin,1,2 and
Konstantin G. Nazarenko3
1National Taras Shevchenko University, ChemBioCenter, Kiev, Ukraine
2Enamine Ltd., Kiev, Ukraine
3Institute of Organic Chemistry, National Academy of Sciences of Ukraine,
Kiev, Ukraine
GRAPHICAL ABSTRACT
Abstract o-Bromoarylsulfonylated amidines prepared either by acylation of amidine with
o-bromoarylsulfonyl chloride or through the reaction of o-bromoarylsulfoamide with
lactime ether underwent Cu(I)-catalyzed intramolecular cyclization to give 4H-1,2,4-
benzothiadiazine-1,1-dioxides in good yield. By varying substituents on arylsulfonyl
moieties, amidines, and lactime ethers, a small library of structurally diverse 4H-1,2,4-
benzothiadiazine-1,1-dioxide derivatives was prepared.
Keywords Acylation; amidines; 1,2,4-benzothiadiazine-1,1-dioxide; copper-catalyzed
cyclization; sulfonyl chlorides
INTRODUCTION
The 1,2,4-benzothiadiazine-1,1-dioxide structural unit is found in compounds
possessing antihypertensive,[1,2] antimicrobial,[3] and antiviral[4] (including anti-HIV)
activities. In connection with this, a range of synthetic pathways to the benzothia-
diazine ring system has been developed. The biologically potent 1,2,4-
benzothiadiazine-1,1-dioxide ring is usually assembled through the reaction of
o-aminoaryl-sulfonamides with either orthoesters[5] or acylating reagents.[6,7] The
main disadvantage of this approach is a limited availability of o-aminosulfonamides,
narrowing the chemical space for drug design. An alternative one-pot approach to
the 1,2,4-benzothiadiazine-1,1-dioxide ring is based on the Michael addition of
chlorosulfonyl isocyanate to aniline derivatives followed by the ring closure under
Received February 17, 2010.
Address correspondence to Oleg Lukin, National Taras Shevchenko University, ChemBioCenter,
Volodymyrska St. 62, 01033 Kiev, Ukraine. E-mail: oleg.lukin@univ.kiev.ua
1977

1978
A. CHEREPAKHA ET AL.
Friedel–Crafts conditions.[8] Despite the ease of the latter procedure, the resulting
sulfonylated urea was shown to be hydrolytically unstable under acidic conditions,
giving rise to an open-chain aminosulfonamide. Recently, a Cu(I)-catalyzed coupling
of o-bromobenzylsulfonyl azide with functionalized terminal acetylene and
ammonium chloride was used for the synthesis of the 4H-1,2,4-benzothiadiazine-
1,1-dioxides.[9] However, the diversity of the target compounds is limited by the
availability of functionalized terminal acetylenes. The benzothiadiazine-1,1-dioxides
were also synthesized through
a Fe(III) chloride–mediated cyclization of
o-bromobenzenesulfonamide with various amidines at 120 ꢀC.[10] Under such harsh
conditions, only 4H-1,2,4-benzothiadiazine-1,1-dioxide derivatives bearing simple
hydrocarbon substituents were synthesized.
We have recently reported that 4H-1,2,4-benzothiadiazine-1,1-dioxides can be
easily synthesized by reacting o-chloroarylsulfonamides with lactime ethers.[11] The
reaction proceeds via formation of a sulfonylated amidine intermediate that under-
goes intramolecular cyclization at 160 ꢀC. Like in the preceding case, the reaction
conditions are quite harsh for many functional groups to survive. In addition, the
presence of electron-withdrawing groups such as NO2 or COOCH3 in the
o-chloroarylsulfonamide component was a prerequisite for the successful cyclization
step. Given the advantages and drawbacks of these synthetic routes to the
benzothiadiazine-1,1-dioxide ring system, it becomes clear that further optimization
of the synthetic schemes is necessary to access its diversely functionalized derivatives.
These points of the published procedures prompted us to the following optimal
scheme: First, the cyclization of the sulfonylated amidine should be carried out
under mild conditions, tolerating a majority of functional groups. For this purpose,
the Cu(I)-catalyzed intramolecular arylation of o-bromobenzenesulfonamide inter-
mediates[9] seems to be the best suited cyclization technique. Second, the preparation
of the sulfonylated amidine intermediate should be more straightforward. It should
involve easily accessible building blocks that bear at least one diversity point each
and react under mild conditions.
In this contribution, we describe two efficient approaches to o-bromoarylsulfo-
nylated amidines and their copper-catalyzed intramolecular cyclization to the
corresponding 4H-1,2,4-benzothiadiazine-1,1-dioxides.
RESULTS AND DISCUSSION
As noted, the most common route to sulfonylated amidines is the reaction of
an amidine with a sulfonamide. The latter is usually prepared from the correspond-
ing sulfonyl chloride. Therefore, a direct sulfonylation of amidines with sulfonyl
chlorides would save one synthetic step.[12] Indeed, as shown in Scheme 1 (route
A) the condensation of o-bromoarylsulfonyl chlorides 1 with amidines 2 in the pres-
1
ence of a base readily gives the sulfonylated amidines 3 in good yield (Table 1). H
NMR spectra of compounds 3a–3h recorded in dimethylsulfoxide (DMSO-d6) con-
tain characteristic signals of the NH2 group at 8.2–8.8 ppm and those of aromatic
proton located in the ortho- position to the sulfo- group at 8.5–8.6 ppm (3b–3d)
and 8.1–8.2 (3e–3h). Notably, the signals pertaining to the NH2 protons in com-
pounds 3 appear as either a broad singlet or two singlets dependently on the
R- groups. Analysis of the literature shows that such spectral manifestations are

SYNTHESIS OF 1,2,4-BENZOTHIADIAZINE-1,1-DIOXIDES
1979
Scheme 1. Preparation of the sulfonylated amidine intermediates.
due to a slow on the NMR timescale rotation of the amino group about the C-N
bond rather than a prototropic equilibrium that takes place only in amidine dimers,
forming themselves in low polar solvents and in the solid state.[13] Additionally, the
=
absence of the terminal C N double bond in sulfonylated amidines was recently pro-
ven by means of single-crystal x-ray diffraction.[14] Amino-group proton signals in the
1H NMR spectra of sulfonylated amidines described in the latter work appear at
1
8.6 ppm, which is in agreement with our own NMR data for compounds 3. H and
13C NMR, liquid chromatography=mass spectrometry (LC=MS), and elemental analy-
ses of the sulfonylated amidines 3a–3h confirmed their composition and high purity.
Given our stock availabilities of many functionalized o-bromoarylsulfonyl chlorides
and amidines, the method can be employed in parallel syntheses of combinatorial
libraries of sulfonylated amidines. To introduce additional structural variations into
the sulfonylated amidine structure, a small library of compounds 6 bearing cyclic func-
tionalities was prepared through condensing o-bromoarylsulfonamides with lactime
ethers (Scheme 1, route B, Table 2) according to our own procedure.[11]
Sulfonylated amidines 3 and 6 underwent the Cu(I)-catalyzed cyclization reac-
tion (Scheme 2) to give the corresponding 4H-1,2,4-benzothiadiazine-1,1-dioxides in
Table 1. Sulfonylated amidines obtained via route A
No.
R1
R2
R3
Solvent
Base
Mp (ꢀC)
Yield (%)
3a
3b
3c
3d
3e
3f
H
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
Br
H
H
H
H
H
H
H
H
Br
Br
CH3
CH3
Ph
benzene
dichloromethane
dichloromethane
dichloromethane
dichloromethane
dichloromethane
benzene
K2CO3
K2CO3
KOH
178
194
95
85
92
83
84
87
92
89
71
89
192
197
Pyrrolidin-1-yl
KOH
KOH
SMe
OMe
CH3
Ph
162
166
KOH
K2CO3
KOH
3g
3h
3i
174 (subl.)
164
158
Br
H
benzene
benzene
benzene
CH3
Ph
K2CO3
KOH
3j
H
137

1980
A. CHEREPAKHA ET AL.
Table 2. Sulfonylated amidines obtained via route B
No.
R1
R2
n
Mp (ꢀC)
Yield (%)
6a
6b
6c
6d
6e
H
CO2Me
CO2Me
Br
H
H
H
H
Br
3
3
5
3
3
159
139 (subl.)
148
98
95
97
94
97
179 (subl.)
184
H
Scheme 2. Cyclization of the sulfonylated amidines obtained via routes A and B.
good yield (Table 2). Noteworthy, the use of N,N0-dimethylethylenediamine
(DMEDA) instead of 1,10-phenanthroline as reported by Chang et al.[9] allowed
1
us to achieve generally better conversions and a clean workup. H and 13C NMR
spectra, LC=MS, and elemental analyses of compounds 7 and 8 are fully consistent
Table 3. 4H-1,2,4-Benzothiadiazines 1,1-dioxides (7)
No.
R1
R2
R3
Mp (ꢀC)
Yield (%)
7a
7b
7c
7d
7e
7f
H
CO2Me
CO2Me
CO2Me
CO2Me
Br
H
H
H
H
H
H
H
Br
Br
CH3
CH3
254
261
98
95
97
93
65
95
98
95
98
Ph
303
322
Pirrolidin-1-yl
OMe
CH3
242
320 (subl.)
349
315
7g
7h
7i
Br
H
Ph
CH3
H
Ph
370 (decomp.)
Table 4. 4H-1,2,4-Benzothidiazine-1,1-dioxides (8)
No.
R1
R2
n
Mp (ꢀC)
Yield (%)
8a
8b
8c
8d
8e
H
CO2Me
CO2Me
Br
H
H
H
H
Br
3
3
5
3
3
296
163
163
263
267
99
97
98
98
98
H

SYNTHESIS OF 1,2,4-BENZOTHIADIAZINE-1,1-DIOXIDES
1981
with their structures. Although this method is not applicable to compound 3d, the
corresponding compound 7 can be synthesized through an alternative solid-phase
synthetic route.[7]
CONCLUSIONS
In conclusion, an efficient and flexible approach to various 4H-1,2,4-
benzothiadiazine-1,1-dioxide derivatives was developed. The structural diversity
of the title compounds is achieved by a two-step synthesis proceeding under mild
conditions. First, o-bromoarylsulfonylated amidines, the key precursors, are
obtained by either of two new procedures from readily available building blocks such
as functionalized bromoarylsulfonyl chlorides, amidines and lactime ethers. The
second step consists of a high-yielding Cu(I)-catalyzed cyclization of the intermedi-
ates. The reported approach broadens considerably the scope of the available meth-
ods by including optimized reaction conditions, new reagents, and structural
subunits, such as cyclic sulfonylated amidines.
EXPERIMENTAL
1H (500-MHz) and 13C (125-MHz) NMR spectra were recorded on a Bruker
Avance DRX 500 spectrometer in DMSO-d6 solution with tetramethylsilane
(TMS) as an internal standard. Melting points were measured with a Buchi
¨
melting-point apparatus and are uncorrected. High-performance (HP) LC-MS
analyses were done on an Agilent 1100 LCMSD SL instrument (APCI mode). The
HPLC-MS data for the compounds reported in this work are available from the
authors upon request. Infrared (IR) spectra were recorded on a Perkin-Elmer Spec-
trum BX II Fourier Transform (FT)–IR spectrometer. Elemental analysis was car-
ried out by the Analytical Laboratory of Institute of Organic Chemistry of NAS.
2-Bromobenzenesulfonyl chloride (1a) and 2-bromosulfonyl amide (4a) were pre-
pared by a procedure of Bahlman.[15] 2,5-Dibromosulfonyl chroride (1c), 2,5-
dibromobenzenesulfonyl amide (4c), and 2,4-dibromobenzenesulfonyl (4d) amide
were prepared using the procedure of Huntress and Carten,[16] and 2,4-dibromoben-
zenesulfonyl (1d) chloride was prepared by the procedure of Pezold et al.[17]
2-Bromo-4-carbomethoxybenzenesulfonyl Chloride (1b)
The 2-bromo-4-carboxybenzenesulfonyl chloride precursor was prepared
according to the published procedure.[18] The precursor (140 g, 0.468 mol) was
dissolved in 300 mL of thionyl chloride and refluxed for 4 h. The excess of thionyl
chloride was removed under reduced pressure, and the viscous residue was slowly
poured into 150 ml of methanol at 0 ꢀC. The 2-bromo-4-carbomethoxybenzene-
sulfonyl chloride precipitated from the solution in the form of a white crystalline
powder. The precipitated product was filtered, washed with cold methanol, and dried
in vacuum. Yield of the pure product is 120 g (82%).
1H NMR (500 MHz, DMSO-d6): d ¼ 3.85 (s, 3 H, CO2CH3), 7.74 (s, 2 H,
ArH), 8.47 (s, 1 H, ArH). 13C NMR (125 MHz, DMSO-d6): d ¼ 52.18, 125.74,
128.71, 129.97, 130.96, 135.08, 147.58, 165.98. Calcd. (%) for C8H6BrClO4S: C
30.65, H 1.93. Found: C 30.52, H 1.95.

1982
A. CHEREPAKHA ET AL.
2-Bromo-4-carbomethoxybenzenesulfonamide (4b)
The 2-bromo-4-carboxybenzenesulfonyl chloride (30 g, 0.1 mol) was slowly
added to 100 mL of concentrated water solution of ammonia at 0 ꢀC, and then the
reaction mixture was stirred for 15 min. The solvent was removed under reduced
pressure, and the residue was dissolved in water. The addition of hydrochloric acid
to the latter solution caused precipitation of the 2-bromo-4-carboxybenzenesulfona-
mide (28 g). The compound was purified by recrystallization from ethanol. The pur-
ified substance was dissolved in methanol, and the solution was transferred into a
three-neck flask equipped with a dropping funnel, reflux condenser, and a mechan-
ical stirrer. Then to the stirred solution thionyl chloride (14.2 g, 0.12 mol) was added
drop wise. Upon addition of the thionyl chloride, the reaction mixture was refluxed
for 1 h, and then the solvent was removed under reduced pressure. The residue was
triturated with water, and the white precipitate was filtered, washed with water and
dried under ambient conditions. The crude product can be additionally purified by
recrystallization from methanol=water mixture. Yield 24 g (81.6%); 1H NMR
(500 MHz, DMSO-d6): d ¼ 3.90 (s, 3 H, CO2CH3), 7.80 (s, 2 H, NH2), 8.00 (s, 2
H, ArH), 8.53 (s, 1 H, ArH). 13C NMR (125 MHz, DMSO-d6): d ¼ 53.22, 124.96,
129.65, 129.85, 133.75, 136.42, 143.77, 165.24. Calcd. (%) for C8H8BrNO4S: C,
32.67; H, 2.74; Br, 27.17; N, 4.76. Found: C, 32.58; H, 2.71; Br, 27.05; N, 4.71.
General Procedure for Preparation of Sulfonylated Amidines
(Route A)
A concentrated water solution of the base (see Table 1) was slowly added to a
stirred solution of equimolar amounts of o-bromoarylsulfonyl chloride 1 and ami-
dine hydrochloride 2 in the appropriate solvent at 0 ꢀC. The reaction mixture was
allowed to stir overnight at room temperature. The precipitated sulfonylated ami-
dine 3 was filtered, washed with water and dichloromethane, and dried at ambient
conditions. If further purification is necessary, the product is recrystallized from
ethanol=water.
Selected Data for 3a–3j
N1-(1-Aminoethylidene)-2-bromobenzenesulfonamide (3a). IR: 3409,
ꢁ1
.
1H NMR
=
3324, 3242 (NH), 1637 (NH2), 1541 (C N), 1288, 1146 (SO2) cm
3
(500 MHz, DMSO-d6): d ¼ 2.12 (s, 3 H, CH3), 7.48 (t, JHH ¼ 7 Hz, 1 H, ArH),
3
3
7.55 (t, JHH ¼ 7 Hz, 1 H, ArH), 7.81 (d, JHH ¼ 7 Hz, 1 H, ArH), 8.06 (d,
3JHH ¼ 7 Hz, 1 H, ArH), 8.13 (b.s., 1 H, NH), 8.56 (b.s., 1 H, NH). 13C NMR
(125 MHz, DMSO-d6): d ¼ 22.17, 120.24, 128.24, 129.61, 133.64, 135.45, 142.48,
168.77. Calcd. (%) for C8H9BrN2O2S: C, 34.67; H, 3.27; Br, 23.83; N, 10.11. Found:
C, 34.62; H, 3.21; Br, 23.75; N, 10.19.
Methyl-3-(1-aminoethylidenesulfamoyl)-4-bromobenzoate (3b). IR: 3331,
ꢁ1
.
1H NMR
=
3131 (NH), 1590 (NH2), 1537 (C N), 1292, 1130 (SO2) cm
(500 MHz, DMSO-d6): d ¼ 2.15 (s, 3 H, CH3), 3.90 (s, 3 H, CO2CH3), 7.97 (s, 2
H, ArH), 8.54 (s, 1 H, ArH), 9.12 (b.s., 2 H, NH). 13C NMR (125 MHz, DMSO-d6):
d ¼ 22.06, 53.17, 125.82, 129.53, 129.71, 133.61, 136.37, 143.15, 165.30, 169.18.

SYNTHESIS OF 1,2,4-BENZOTHIADIAZINE-1,1-DIOXIDES
1983
Calcd. (%) for C10H11BrN2O4S: C, 35.84; H, 3.31; Br, 23.84; N, 8.36. Found: C,
35.75; H, 3.22; Br, 23.67; N, 8.15.
Methyl-3-(amino(phenyl)methylenesulfamoyl)-4-bromobenzoate (3c).
1
IR: 3335, 3177 (NH), 1586 (NH2), 1482 (C N), 1297, 1174 (SO2) cmꢁ1. H NMR
=
3
(500 MHz, DMSO-d6): d ¼ 3.90 (s, 3 H, CO2CH3), 7.49 (t, JHH ¼ 8 Hz, 2 H,
3
3
ArH), 7.60 (t, JHH ¼ 8 Hz, 1H, ArH), 7.91 (t, JHH ¼ 8 Hz, 2 H, ArH), 8.00 (s, 2
H, ArH), 8.41 (b.s., 1 H, NH), 8.54 (s, ArH), 9.33 (b.s, 1 H, NH). 13C NMR
(125 MHz, DMSO-d6): d ¼ 52.83, 125.79, 128.57, 128.64, 128.70, 129.49, 130.00,
130.93, 134.27, 135.08, 147.73, 166.00, 166.10. Calcd. (%) for C15H13BrN2O4S: C,
45.35; H, 3.30; Br, 20.11; N, 7.05. Found: C, 45.02; H, 3.37; Br 19.89; N, 6.92.
Methyl-3-(amino(tetrahydro-1H-pyrrolyl)methylenesulfamoyl)-4-bromo-
=
benzoate (3d). IR: 3419, 3326, 3233 (NH), 1586 (NH2), 1558 (C N), 1285, 1193
1
(SO2) cmꢁ1. H NMR (500 MHz, DMSO-d6): d ¼ 1.85 (m, 4 H, CH2), 3.36 (m, 4
H, NCH2), 3.89 (s, 3 H, CO2CH3), 7.014 (b.s., 2 H, NH), 7.93 (s, 2 H, ArH), 8.55
(s, 1 H, ArH). 13C NMR (125 MHz, DMSO-d6): d ¼ 24.87, 25.43, 46.25, 47.88,
53.10, 125.49, 129.33, 129.79, 133.07, 136.36, 144.28, 154.60, 165.42. Calcd. (%)
for C13H16BrN3O4S: C, 40.01; H, 4.13; Br, 20.47; N, 10.77. Found: C, 39.82; H,
4.05; Br, 20.32; N, 10.54.
Methyl-3-(amino(methylthio)methylenesulfamoyl)-4-bromobenzoate
(3e). IR: 3433, 3335 (NH), 1588 (NH2), 1533 (C N), 1283, 1147 (SO2) cmꢁ1. H
1
=
NMR (500 MHz, DMSO-d6): d ¼ 2.32 (s, 3 H, SCH3), 3.9 (s, 3 H, CO2CH3), 8.00
(s, 2 H, ArH), 8.21 (b.s., 1 H, NH), 8.55 (s, 1 H, ArH), 8.93 (b.s., 1 H, NH). 13C
NMR (125 MHz, DMSO-d6): d ¼ 14.24, 53.18, 125.70, 129.55, 130.18, 133.96,
136.52, 142.46, 165.24, 170.34. Calcd. (%) for C10H11BrN2O4S2: C, 32.71; H, 3.02;
Br, 21.76; N, 7.63. Found: C, 32.52; H, 3.09; Br, 21.53; N, 7.52.
Methyl-3-(amino(methoxy)methylene)sulfamoyl)-4-bromobenzoate (3f).
1
IR: 3442, 3321 (NH), 1620 (NH2), 1546 (C N), 1281, 1149 (SO2) cmꢁ1. H NMR
=
(500 MHz, DMSO-d6): d ¼ 3.7 (s, 3 H, OCH3), 3.9 (s, 3 H, CO2CH3), 7.43 (b.s., 1
H, NH), 8.00 (s, 2 H, ArH), 8.45 (b.s., 1 H, NH), 8.60 (s, 1 H, ArH). 13C NMR
(125 MHz, DMSO-d6): d ¼ 53.17, 55.53, 125.53, 129.60, 130.10, 133.92, 136.93,
142.53, 160.64, 165.25. Calcd. (%) for C10H11BrN2O5S: C, 34.20; H, 3.16; Br,
22.75; N, 7.98. Found: C, 34.03; H, 3.24; Br, 22.53; N, 8.02.
N1-(1-Aminoethilidene)-2,5-dibromo-1benzenesulfonamide
=
(3g). IR:
1
3224, 3140 (NH2), 1620 (NH2), 1442 (C N), 1248, 1151 (SO2) cmꢁ1. H NMR
3
(500 MHz, DMSO-d6): d ¼ 2.14 (s, 3 H, CH3), 7.75 (d, JHH ¼ 8 Hz, 1 H, ArH),
3
7.69 (d, JHH ¼ 8 Hz, 1 H, ArH), 8.13 (s, 1 H, ArH), 8.55 (b. s. 2 H, NH). 13C
NMR (125 MHz, DMSO–d6): d ¼ 22.18, 119.36, 120.98, 131.82, 136.29, 137.48,
144.19, 169.18. Calcd. (%) for C8H8Br2N2O2S: C, 26.99; H, 2.26; Br, 44.89; N,
7.87. Found: C, 26.77; H, 2.22; Br, 44.68; N, 7.76.
N1-Amino(phenyl)methylene-2,5-dibromo-1-benzenesulfonamide (3h).
1
IR: 3428, 3315, 3247 (NH), 1617 (NH2), 1512 (C N), 1282, 1140 (SO2) cmꢁ1. H
=
3
NMR (500 MHz, DMSO-d6): d ¼ 7.49 (t, JHH ¼ 7 Hz, 2 H, ArH), 7.60 (t,
3
3
3JHH ¼ 7 Hz, 1 H, ArH), 7.72 (d, JHH ¼ 7 Hz, 1 H, ArH), 7.77 (d, JHH ¼ 7 Hz, 1
3
H, ArH), 7.90 (d, JHH ¼ 7 Hz, 2 H, ArH), 8.28 (s, 1 H, ArH), 8.74 (b.s., 2, H,

1984
A. CHEREPAKHA ET AL.
NH). 13C NMR (125 MHz, DMSO-d6): d ¼ 119.51, 121.07, 128.60, 128.95, 132.30,
133.01, 133.69, 136.60, 137.56, 143.63, 164.07. Calcd. (%) for C13H10Br2N2O2S: C,
37.35; H, 2.41; Br, 38.22; N, 6.70. Found: C, 37.07; H, 2.38; Br, 38.33; N, 6.58.
1
N1-(1-Iminoethylidene)-2,4-dibromo-1-benzenesulfonamide (3i). H NMR
3
(500 MHz, DMSO-d6): d ¼ 2.12 (s, 3 H, CH3), 7.76 (d, JHH ¼ 8 Hz, 1 H, ArH),
3
7.96 (d, JHH ¼ 8 Hz, 1 H, ArH), 8.06 (s, 1 H, ArH), 8.18 (b.s, 1 H, NH), 8.62
(b.s., 1 H, NH). 13C NMR (125 MHz, DMSO-d6): d ¼ 22.11, 121.43, 126.07,
131.11, 131.30, 137.25, 141.99, 169.03. Calcd. (%) for C8H8Br2N2O2S: C, 26.99; H,
2.26; Br, 44.89; N, 7.87. Found: C, 27.05; H, 2.23; Br, 44.52; N, 7.72.
N1-Amino(phenyl)methylene-2,4-dibromo-1-benzenesulfonamide (3j).
1
IR: 3405, 3317, 3228 (NH), 1625 (NH2), 1528 (C N), 1278, 1153 (SO2) cmꢁ1. H
=
3
NMR (500 MHz, DMSO-d6): d ¼ 7.48 (t, JHH ¼ 8 Hz, 2 H, ArH), 7.6 (t,
3
3
3JHH ¼ 8 Hz, 1 H, ArH), 7.80 (d, JHH ¼ 8.5 Hz, 1 H, ArH), 7.88 (d, JHH ¼ 8 Hz,
2 H, ArH), 8.05–8.1 (m, 2 H, ArH), 8.29 (b.s., 1 H, NH), 9.27 (b.s., 1 H, NH).
13C NMR (125 MHz, DMSO-d6): d ¼ 121.59, 126.60, 128.57, 128.89, 131.35,
131.41, 133.05, 133.59, 137.43, 141.30, 163.88. Calcd. (%) for C13H10Br2N2O2S: C,
37.35; H, 2.41; Br, 38.22; N, 6.70. Found: C, 37.02; H, 2.38; Br, 38.03; N, 6.59.
General Procedure for Preparation of Sulfonylated Amidines
(Route B)
Lactime ether 5 (1.2 eq) was added to a solution of o-bromoarylsulfonamide 4
in ethanol. The reaction mixture was refluxed for 8 h, and then the solvent was
removed under reduced pressure. The residue was triturated with water, and the
resulting precipitate was filtered, thoroughly washed with water, and dried at ambi-
ent conditions. If further purification is necessary the product is recrystallized from
methanol.
Selected Data for 6a–6e
2-(2-Bromophenylsulfonylimino)pyrrolidine (6a). IR: 3409, 3321, 3205
.
1H NMR (500 MHz, DMSO-d6):
ꢁ1
3
=
(NH), 1563 (C N), 1300, 1148 (SO2) cm
d ¼ 2.03–1.98 (m, 2 H, CH2), 2.76 (t, JHH ¼ 8.5 Hz, 2 H, CH2), 3.42 (t,
3JHH ¼ 8.5 Hz, 2 H, CH2), 7.48 (t, JHH ¼ 7.5 Hz, 1H, ArH), 7.55 (t, JHH ¼ 7.5 Hz,
3
3
3
3
1 H, ArH), 7.79 (d, JHH ¼ 7.5 Hz, 1 H, ArH), 8.06 (d, JHH ¼ 7.5 Hz, 1 H, ArH),
9.12 (b.s., 1 H, NH). 13C NMR (125 MHz, DMSO-d6): d ¼ 20.92, 32.25, 46.37,
120.20, 128.25, 129.71, 133.58, 135.44, 142.63, 173.16. Calcd. (%) for
C10H11BrN2O2S: C, 39.62; H, 3.66; Br, 26.36; N, 9.24. Found: C, 39.24; H, 3.71;
Br, 26.15; N, 9.17.
Metyl-4-bromo-3-tetrahydro-1H-2-pyrrolydensulfamoylbenzoate (6b).
ꢁ1
.
1H NMR
=
IR: 3382, 3275, 3126 (NH), 1588 (C N), 1281, 1153 (SO2) cm
3
3
(500 MHz, DMSO-d6): d ¼ 2.03 (p, JHH ¼ 7 Hz, 2 H, CH2), 2.79 (t, JHH ¼ 7 Hz, 2
3
H, CH2), 3.43 (t, JHH ¼ 7 Hz, 2 H, CH2), 3.90 (s, 3 H, CO2CH3), 7.97 (s, 2 H,
ArH), 8.55 (s, 1 H, ArH), 9.23 (b.s., 1 H, NH). 13C NMR (125 MHz, DMSO-d6):
d ¼ 20.96, 32.30, 45.38, 53.17, 125.81, 129.55, 129.86, 133.56, 136.36, 143.26,

SYNTHESIS OF 1,2,4-BENZOTHIADIAZINE-1,1-DIOXIDES
1985
163.52, 173.47. Calcd. (%) for C12H13BrN2O4S: C, 39.90; H, 3.63; Br, 22.21; N, 7.76.
Found: C, 40.06; H, 3.58; Br, 22.02; N, 7.82.
Methyl-3-(2-azapanylidensulfamoyl)-4-bromobenzoate (6c). IR: 3419,
1
3326 (NH), 1528 (C N), 1283, 1149 (SO2) cmꢁ1. H NMR (500 MHz, DMSO-d6):
=
d ¼ 1.36–1.60 (m, 2 H, CH2), 1.62–1.70 (m, 2 H, CH2), 2.72 (m, 2 H, CH2), 3.90
(s, 3 H, CO2CH3), 7.97 (s, 2 H, ArH), 8.55 (s, 1 H, ArH), 8.92 (b.s., 1 H, NH).
13C NMR (125 MHz, DMSO-d6): d ¼ 23.20, 28.44, 29.70, 34.54, 43.77, 53.18,
125.88, 129.52, 129.66, 133.64, 136.39, 143.14, 165.27, 173.38. Calcd. (%) for
C14H17BrN2O4S: C, 43.20; H, 4.40; Br, 20.53; N, 7.20. Found: C, 43.05; H, 4.32;
Br, 20.37; N, 7.32.
2-(2,5-Dibromophenylsulfonyliminoꢁ)p1 yrrolidine (6d). IR: 3224, 3140
=
(NH), 1618 (C N), 1301, 1151 (SO2) cm
.
1H NMR (500 MHz, DMSO-d6):
3
3
d ¼ 2.02 (m, 2 H, CH2), 2.97 (t, JHH ¼ 7 Hz, 2 H, CH2), 3.43 (t, JHH ¼ 7 Hz, 2 H,
3
3
4
CH2), 7.74 (d, JHH ¼ 8.5 Hz, 1 H, ArH), 7.69 (dd, JHH ¼ 8.5 Hz, JHH ¼ 2 Hz,
3
ArH), 8.13 (d, JHH ¼ 2 Hz, 1 H, ArH), 9.23 (b.s., 1 H, NH). 13C NMR
(125 MHz, DMSO-d6): d ¼ 20.94, 32.24, 45.40, 121.43, 126.02, 131.22, 131.31,
137.23, 142.09, 173.41. Calcd. (%) for C10H10Br2N2O2S: C, 31.44; H, 2.64; Br,
41.38; N, 7.33. Found: C, 31.21; H, 2.69; Br, 41.39; N, 7.21.
2-(2,4-Dibromophenylsulfonylimino)pyrrolidine (6e). IR: 3205, 3113
ꢁ1
=
(NH) 1563 (C N), 1299, 1151 (SO2) cm
.
1H NMR (500 MHz, DMSO-d6):
3
3
d ¼ 2.01 (t, JHH ¼ 7 Hz, 2 H, CH2), 2.77 (t, JHH ¼ 7 Hz, 2 H, CH2), 3.42 (t,
3
4
3JHH ¼ 7 Hz, 2 H, CH2), 7.6 (dd, JHH ¼ 8 Hz, JHH ¼ 2 Hz, 1 H, ArH), 7.97 (d,
3
3JHH ¼ 8 Hz, 1 H, ArH), 8.04 (d, JHH ¼ 2 H, 1 H, ArH), 9.18 (b.s., 1 H, NH).
13C NMR (125 MHz, DMSO-d6): d ¼ 20.94, 32.24, 45.40, 121.43, 126.02, 131.22,
131.31, 137.23, 142.09, 173.41. Calcd. (%) for C10H10Br2N2O2S: C, 31.44; H, 2.64;
Br, 41.38; N, 7.33. Found: C, 31.25; H, 2.59; Br, 41.72; N, 7.28.
General Procedure for Preparation of 4H-1,2,4-Benzothiadiazine-
1,1-dioxides (7)
Potassium carbonate (2 eq), 5 mol% of Cu (I) iodide, and 10 mol% of DMEDA
were added to a DMF solution of a sulfonylated amidine (3) under argon flow. The
reaction mixture was stirred under argon at 70 ꢀC for 8 h. After that, solvent was
removed at reduced pressure. The residue was dissolved in water and acidified
to pH 1. The precipitate was filtered out, washed with water, and dried at ambient
condition.
Selected Data for 7a–7i
3-Methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide (7a). Mp 254 ꢀC (pre-
1
viously reported 254–255 ꢀC[9]). H NMR (500 MHz, DMSO-d6): d ¼ 2.31 (s, 3 H,
3
3
CH3), 7.30 (d, JHH ¼ 8 Hz, 1 H, ArH), 7.43 (t, JHH ¼ 8 Hz, 1 H, ArH), 7.67 (t,
3JHH ¼ 8 Hz, 1 H, ArH), 7.79 (d, JHH ¼ 8 Hz, ArH), 12.03 (b.s., 1 H, NH). 13C
3
NMR (125 MHz, DMSO-d6): d ¼ 23.20, 120.09, 120.52, 126.18, 126.25, 129.56,

1986
A. CHEREPAKHA ET AL.
136.97, 158.04. Calcd. (%) for C8H8N2O2S: C, 48.97; H, 4.11; N, 14.28. Found: C,
48.75; H, 4.05; N, 14.53.
Methyl-1,1-dioxo-3-methyl-4H-1,2,4-benzothiadiazine-7-carboxylate (7b).
IR: 1244, 1133 (SO2) cmꢁ1. 1H NMR (500 MHz, DMSO-d6): d ¼ 2.34 (s, 3 H, CH3),
3
3
3.90 (s, 3 H, CO2CH3), 7.43 (d, JHH ¼ 9 Hz, 1 H, ArH), 8.18 (dd, JHH ¼ 9 Hz,
4JHH ¼ 2 Hz, 1 H, ArH), 8.25 (d, JHH ¼ 2 Hz, ArH), 12.43 (b.s., 1 H, NH). 13C
3
(125 MHz, DMSO-d6): d ¼ 23.21, 53.01, 118.48, 121.24, 125.47, 127.42, 133.66,
139.14, 158.49, 164.90. Calcd. (%) for C10H10N2O4S: C, 47.24; H, 3.96; N, 11.02.
Found: C, 47.02; H, 3.92; N, 11.15.
Methyl-1,1-dioxo-3-phenyl-4H-1,2,4-benzothiadiazine-7-carboxylate
(7c). IR: 1246, 1123 (SO2) cmꢁ1. 1H NMR (500 MHz, DMSO-d6): d ¼ 3.90 (s, 3 H,
CO2CH3), 7.6–7.68 (m, 2 H, ArH), 7.69–7.82 (m, 2 H, ArH), 8.0–8.1 (m, 2 H, ArH),
3
8.25 (d, JHH ¼ 7.5 Hz, 1 H, ArH), 8.32 (s, 1 H, ArH) 12.55 (b.s., 1 H, NH). 13C
NMR (125 MHz, DMSO-d6): d ¼ 53.11, 119.74, 121.62, 125.30, 128.00, 128.87,
129.45, 131.87, 133.80, 133.81, 139.44, 155.96, 164.98. Calcd. (%) for C15H12N2O4S:
C, 56.95; H, 3.82; N, 8.86. Found: C, 56.72; H, 3.85; N, 8.78.
Methyl-1,1-dioxo-3-(tetrahydro-1H-1-pyrrolyl)-4H-1,2,4-benzothiadia-
zine-7-carboxylate (7d). IR: 1251, 1121 (SO2) cmꢁ1 1H NMR (500 MHz,
.
DMSO-d6): d ¼ 1.8 (m, 4 H, CH2), 3.4–3.65 (m, 4 H, CH2), 3.87 (s, 3 H, CO2CH3),
3
3
7.61 (d, JHH ¼ 8 Hz, 1 H, ArH), 8.10 (d, JHH ¼ 8 Hz, ArH), 8.17 (s, 1 H, ArH),
10.62 (b.s., 1 H, NH). 13C NMR (125 MHz, DMSO-d6): d ¼ 25.19, 47.78, 52.80,
118.30, 123.21, 124.57, 125.19, 133.00, 140.35, 149.19, 165.29. Calcd. (%) for
C13H15N3O4S: C, 50.48; H, 4.89; N, 13.58. Found: C, 50.53; H, 4.82; N, 13.62.
Methyl-1,1-dioxo-3-methoxy-4H-1,2,4-benzothiadiazine-7-carboxylate
(7e). IR: 1251, 1133 (SO2) cmꢁ1. 1H NMR (500 MHz, DMSO-d6): d ¼ 3.87 (s, 3 H,
3
CO2CH3), 3.93 (s, 3 H, OCH3), 7.47 (d, JHH ¼ 8 Hz, 1 H, ArH), 8.14 (d,
3JHH ¼ 8 Hz, 1 H, ArH), 8.22 (s, 1 H, ArH), 12.74 (b.s., 1 H, NH). 13C NMR
(125 MHz, DMSO-d6): d ¼ 52.96, 56.19, 118.21, 121.60, 125.28, 126.41, 133.91,
138.69, 154.67, 164.99. Calcd. (%) for C10H10N2O5S: C, 44.44; H, 3.73; N, 10.37.
Found: C, 44.27; H, 3.68; N, 10.25.
7-Bromo-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide (7f). Mp 320 ꢀC
1
(sublimation; previously reported 333–335 ꢀC[20]). IR: 1281, 1133 (SO2) cmꢁ1. H
3
NMR (500 MHz, DMSO-d6): d ¼ 2.31 (s, 3 H, CH3), 7.28 (d, JHH ¼ 8.5 Hz, 1 H,
3
4
3
ArH), 7.83 (dd, JHH ¼ 8.5 Hz, JHH ¼ 2 Hz, 1 H, ArH), 7.93 (d, JHH ¼ 2 Hz,
ArH). 13C NMR (125 MHz, DMSO-d6): d ¼ 23.14, 117.53, 120.30, 122.84, 126.02,
134.92, 136.40, 157.99. Calcd. for C8H7BrN2O2S: C, 34.93; H, 2.56; Br, 29.04; N,
10.18. Found: C, 34.81; H, 2.52; Br, 29.13; N, 10.08.
7-Bromo-3-phenyl-4H-1,2,4-benzothiadiazine-1,1-dioxide (7g). Mp 349 ꢀC
1
(formerly reported 348–349 ꢀC[20]). H NMR (500 MHz, DMSO-d6): d ¼ 7.55–7.66
3
(m, 2 H, ArH), 766–7.76 (m, 2 H, ArH), 7.93 (d, JHH ¼ 8 Hz, 1 H, ArH), 8.02 (s,
3
1H, ArH), 8.08 (d, JHH ¼ 7 Hz, 2 H, ArH), 12.47 (b.s., 1 H, NH). 13C NMR
(125 MHz, DMSO-d6): d ¼ 118.24, 121.58, 125.90, 128.86, 129.36, 132.02, 133.50,
135.30, 136.53, 155.38. Calcd. (%) for C13H9BrN2O2S: C, 46.31; H, 2.69; Br,
23.70; N, 8.31. Found: C, 46.23; H, 2.66; Br, 23.54; N, 8.27.

SYNTHESIS OF 1,2,4-BENZOTHIADIAZINE-1,1-DIOXIDES
1987
6-Bromo-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide (7h). Mp 315 ꢀC
(formerly reported 312–316 ꢀC[6]). 1H NMR (500 MHz, DMSO-d6): d ¼ 2.32 (s, 3 H,
CH3), 7.46 (s, 1 H, ArH), 7.61 (d, 3JHH ¼ 8 Hz, 1 H, ArH), 7.76 (d, 3JHH ¼ 8 Hz, 1 H,
ArH), 12.12 (b.s., 1 H, NH). 13C NMR (125 MHz, DMSO-d6): d ¼ 23.20, 120.09,
120.52, 126.18, 126.25, 129.56, 136.97, 158.04. Calcd for C8H7BrN2O2S: C, 34.93;
H, 2.56; Br, 29.04; N, 10.18. Found: C, 34.68; H, 2.59; Br, 28.92; N, 10.09.
6-Bromo-3-phenyl-4H-1,2,4-bezothiadiazine-1,1-dioxide (7i). IR: 1251,
1
3
1147 (SO2) cmꢁ1. H NMR (500 MHz, DMSO-d6): d ¼ 7.63 (t, JHH ¼ 8 Hz, 2 H,
3
3
ArH), 7.70 (t, JHH ¼ 8 Hz, 2 H, ArH), 7.83 (d, JHH ¼ 8 Hz, 1 H, ArH), 7.89 (s, 1
H, ArH), 8.05 (d, JHH ¼ 8 Hz, 2 H, ArH), 12.35 (b.s., 1 H, NH). 13C NMR
3
(125 MHz, DMSO-d6): d ¼ 120.98, 121.48, 126.04, 126.35, 128.80, 129.41, 130.06,
132.02, 133.55, 137.32, 155.43. Calcd. (%) for C13H9BrN2O2S: C, 46.31; H, 2.69;
Br, 23.70; N, 8.31. Found: C, 46.28; H, 2.64; Br, 23.14; N, 8.25.
General Procedure for Preparation of 4H-1,2,4-Benzothiadiazine-
1,1-dioxides (8)
Potassium carbonate (2 eq), 5 mol % of Cu (I) iodide, and 10 mol. % of
DMEDA were added to a DMF solution of a sulfonylated amidine (6) under argon
flow. The reaction mixture was stirred under argon at 70 ꢀC for 8 hrs. After that
precipitate was filtered out and solvent was removed at reduced pressure. Residue
diluted with water and filtered out, washed with water and dried at ambient
condition.
Selected Data for 8a–8e
5,5-Dioxo-1H,2H,3H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine (8a). Mp
1H NMR
296 ꢀC (formerly reported 297 ꢀC[19]). IR: 1285, 1147 (SO2) cmꢁ1
.
3
(500 MHz, DMSO-d6): d ¼ 2.13–2.26 (m, 2 H, CH2), 2.97 (t, JHH ¼ 7.5, Hz 2 H,
3
3
CH2), 4.15 (t, JHH ¼ 7.5 Hz, 2 H, CH2), 7.39 (d, JHH ¼ 8 Hz, 1 H, ArH), 7.52 (t,
3JHH ¼ 8 Hz, 1 H, ArH), 7.76 (t, JHH ¼ 8 Hz, 1 H, ArH), 7.87 (d, JHH ¼ 8 Hz, 1
H, ArH). 13C NMR (500 MHz, DMSO-d6): d ¼ 18.24, 33.76, 50.38, 116.77, 121.64,
124.40, 126.67, 133.64, 135.14, 163.81. Calcd. (%) for C10H10N2O2S: C, 54.04; H,
4.53; N, 12.60. Found: C, 54.11; H, 4.48; N, 12.38.
3
3
5,5-Dioxo-7-methyloxycarbonyl-1H,2H,3H-benzo[e]pyrrolo[2,1-c][1,2,4]-
1
thiadiazine (8b). IR: 1292, 1153 (SO2) cmꢁ1. H NMR (500 MHz, DMSO-d6):
d ¼ 2.15–2.3 (m, 2 H, CH2), 2.95–3.1 (m, 2 H, CH2), 3.9 (s, 3 H, CO2CH3),
3
3
4.1–4.3 (m, 2 H, CH2), 7.52 (d, JHH ¼ 8 Hz, 1 H, ArH), 8.24 (d, JHH ¼ 8 Hz, 1
H, ArH), 8.3 (s, 1 H, ArH). 13C NMR (125 MHz, DMSO-d6): d ¼ 18.28, 33.84,
50.74, 53.09, 117.66, 121.34, 125.62, 127.36, 133.78, 138.46, 164.69, 164.86. Calcd.
(%) for C12H12N2O4S: C, 51.42; H, 4.32; N, 9.99. Found: C, 51.32; H, 4.26; N, 10.01.
5,5-Dioxo-7-methyloxycarbonyl-7H,8H,9H,10H,11H-benzo[5,6][1,2,4]-
1
thiadiazino[4,3-a]azepin (8c). IR: 1292, 1167 (SO2) cmꢁ1. H NMR (500 MHz,
DMSO-d6): d ¼ 1.74 (m, 4 H, CH2), 1.82 (m, 2 H, CH2), 3.00 (m, 2H, CH2), 3.90
3
(s, 3 H, CO2CH3), 4.30 (m, 2 H, CH2), 7.80 (d, JHH ¼ 8 Hz, 1 H, ArH), 8.25

1988
A. CHEREPAKHA ET AL.
3
(d, JHH ¼ 8 Hz, 1 H, ArH), 8.30 (s, 1 H, ArH). 13C NMR (125 MHz, DMSO-d6):
d ¼ 24.37, 26.19, 28.01, 38.06, 49.24, 53.09, 117.97, 123.14, 125.43, 127.24, 133.89,
141.50, 164.81, 167.03. Calcd. (%) for C14H16N2O4S: C, 54.53; H, 5.23; N, 9.08.
Found: C, 54.39; H, 5.33; N, 9.13.
7-Bromo-5,5-dioxo-1H,2H,3H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine
(8d). 1H NMR (500 MHz, DMSO-d6): d ¼ 2.1–2.25 (m, 2 H, CH2), 2.96 (t,
3
3
3JHH ¼ 6 Hz, 2 H, CH2), 4.14 (t, JHH ¼ 6 Hz, 2 H, CH2), 7.38 (d, JHH ¼ 8 Hz, 1
H, ArH), 7.95 (d, JHH ¼ 8 Hz, 1 H, ArH), 8.00 (s, 1 H, ArH). 13C NMR
3
(125 MHz, DMSO-d6): d ¼ 18.14, 33.79, 50.60, 117.96, 119.52, 122.96, 126.50,
134.44, 136.42, 164.10. Calcd. (%) for C10H9BrN2O2S: C, 39.88; H, 3.01; Br,
26.53; N, 9.30. Found: C, 39.82; H, 2.97; Br, 26.64; N, 9.23.
6-Bromo-5,5-dioxo-1H,2H,3H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine
(8e). IR: 1290, 1156 (SO2) cmꢁ1. 1H NMR (500 MHz, DMSO-d6): d ¼ 2.12–2.24 (m,
2 H, CH2), 2.98 (t, 3JHH ¼ 8.5 Hz, 2 H, CH2), 4.15 (t, 3JHH ¼ 8.5 Hz, 2 H, CH2), 7.66
(s, 1 H, ArH), 7.70 (d, 3JHH ¼ 8 Hz, 1 H, ArH), 7.81 (dd, 3JHH ¼ 8 Hz, 4JHH ¼ 2 Hz, 1
H, ArH). 13C NMR (125 NHz, DMSO-d6): d ¼ 18.25, 33.82, 50.66, 119.56, 120.53,
126.46, 126.89, 129.61, 136.41, 164.24. Calcd. (%) for C10H9BrN2O2S: C, 39.88; H,
3.01; Br, 26.53; N, 9.30. Found: C, 39.67; H, 3.04; Br, 26.37; N, 9.24.
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