Synthesis and anticancer activity of 2-amino-8-chloro-5,5-dioxo[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazine derivatives

Article abstract of DOI:10.1016/S0968-0896(02)00638-7

A new series of 1-(6-chloro-1,1-dioxo-1,4,2-benzodithiazin-3-yl)-4-arylsemicarbazides (4-16) were obtained. Intramolecular ring closure in semicarbazides 4-16 upon treatment with phosphorus oxychloride resulted in the formation of 2-amino-8-chloro-5,5-dioxo[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazines 17-29 with potential antitumor activity. The structures of these compounds were confirmed on the basis of elemental analysis, spectral data and X-ray analysis. Compounds 17-29 were screened at the US National Cancer Institute (NCI) for their activities against a panel of 59 tumor cell lines, and relationships between structure and antitumor activity in vitro are discussed. The benzodithiazines 18, 19, 23, 28 and 29 were inactive, whereas the other compounds exhibited reasonable activity against numerous human tumor cell lines. The prominent compound 17 showed significant activity against the leukemia SR cell line (log GI₅₀=-7.67, log TGI=-6.90 and log LC₅₀=-4.77).

Full text of DOI:10.1016/S0968-0896(02)00638-7

Bioorganic & Medicinal Chemistry 11 (2003) 1259–1267
Synthesis and Anticancer Activity of 2-Amino-8-chloro-5,5-
dioxo[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazine Derivatives
.
Elzbieta Pomarnackaa,* and Maria Gdaniecb
a
´
Department of Chemical Technology of Drugs, Medical University of Gdansk,
´
107 Gen.J.Hallera Str., 80-416 Gdansk, Poland
Faculty of Chemistry, A.Mickiewicz University, 60-780 Poznan , Poland
b
´
Received 13 September 2002; revised 14November 2002; accepted 29 November 2002
Abstract—A new series of 1-(6-chloro-1,1-dioxo-1,4,2-benzodithiazin-3-yl)-4-arylsemicarbazides (4–16) were obtained. Intramolec-
ular ring closure in semicarbazides 4–16 upon treatment with phosphorus oxychloride resulted in the formation of 2-amino-8-
chloro-5,5-dioxo[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazines 17–29 with potential antitumor activity. The structures of these com-
pounds were confirmed on the basis of elemental analysis, spectral data and X-ray analysis. Compounds 17–29 were screened at the
US National Cancer Institute (NCI) for their activities against a panel of 59 tumor cell lines, and relationships between structure
and antitumor activity in vitro are discussed. The benzodithiazines 18, 19, 23, 28 and 29 were inactive, whereas the other com-
pounds exhibited reasonable activity against numerous human tumor cell lines. The prominent compound 17 showed significant
activity against the leukemia SR cell line (log GI50=ꢀ7.67, log TGI=ꢀ6.90 and log LC50=ꢀ4.77).
# 2003 Elsevier Science Ltd. All rights reserved.
Results and Discussion
Introduction
The sulfonamides constitute an important class of ther-
apeutic agents in current medicinal science and various
structurally novel sulfonamide derivatives have recently
been reported to show substantial antitumor and anti-
HIV activities.1ꢀ4 Although they have a common chem-
ical motif of an aromatic/heterocyclic sulfonamide,
there are a variety of mechanisms for their anticancer
action, such as disruption of microtubule assembly, cell
cycle arrest in the G1 phase, functional suppression of
the transcriptional activator NF-Y, angiogenesis inhibi-
tion as well as carbonic anhydrase inhibition.5 Our sys-
tematic studies on the synthesis of 1,4,2-benzodithiazine
1,1-dioxides, and their subsequent transformation into
N-(azolyl or azinyl)-2-mercaptobenzenesulfonamides (I,
MBSAs) resulted in promising anticancer agents6ꢀ13 or
potent inhibitors of HIV-1 integrase.14ꢀ17 We also
found that cyclic sulfonamide derivatives of 8-chloro-
5,5-dioxoimidazo[1,2-b][1,4,2]benzodithiazine of type II
possessed interesting anticancer properties (Fig. 1).18,19
This prompted us to investigate further the chemistry
and biological activity of the related new heterocyclic
ring system III.
The reaction of 6-chloro-3-methylthio-1,1-dioxo-1,4,2-
benzodithiazine 1–3 with the appropriate 4-arylsemi-
carbazides20 were performed in boiling methanol to give
1-(6-chloro-1,1-dioxo-1,4,2-benzodithiazin-3-yl)-4-aryl-
semicarbazides 4–16. When the semicarbazides 4–16, in
turn, were subjected to the reaction with POCl3 the tar-
get 8-chloro-2-arylamino-5,5-dioxo-7-R1-[1,2,4]tria-
zolo[2,3-b][1,4,2]benzodithiazines 17–29 were obtained
in 27–56% of separated yields (Scheme 1). A probable
mechanism of the reaction course is shown in Scheme 2.
First, upon treatment of semicarbazides 4–16 with
POCl3 imidoyl chloride of type A is formed, which
undergoes intramolecular ring closure with evolution of
HCl to give triazolo[4,3-b][1,4,2]benzodithiazine B.
Under acidic conditions, a scission of SO2–N bond
takes place with formation of a sulfonyl chloride D,
which, in turn cyclizes to a more stable triazo-
lo[2,3-b][1,4,2]benzodithiazines 17–29. The structures of
the compounds 4–16 and the final products 17–29 were
1
confirmed by elemental analyses, IR, H NMR and 13C
NMR spectrophotometry. It is worth noting, however,
that the spectroscopic data did not allow straightfor-
ward discrimination between the actual triazo-
lo[2,3-b][1,4,2]benzodithiazine structure and the
*Corresponding author. E-mail: zopom@farmacja.amg.gda.pl
0968-0896/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0968-0896(02)00638-7

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E.Pomarnacka, M.Gdaniec / Bioorg.Med.Chem.11 (2003) 1259–1267
Figure 1.
Scheme 1. Synthesis of 8-chloro-2-arylamino-5,5-dioxo[1,24]triazolo[2,3-b][1,4,2]benzodithiazines 17–29. Reagents: (a) 4-arylsemicarbazide, MeOH,
reflux; (b) (1) POCl3, reflux/18 h; (2) ice/H2O, pH=7; (3) recrystallization from DMF.
alternative
triazolo[4,3-b][1,4,2]benzodithiazine
B
079(3) A, H14ꢂ ꢂ ꢂN10 2.46(3) A, <N14–H14ꢂ ꢂ ꢂN10
178ꢁ]. The dimer structure leads to a pair of short C–
Hꢂ ꢂ ꢂS contacts [C16ꢂ ꢂ ꢂS40 3.638(2) A, C16–H16 0.96(3)
A, H16ꢂ ꢂ ꢂS40 2.83(3) A, <C16–H16ꢂ ꢂ ꢂS40 178ꢁ] between
the two molecules (Fig. 2).
(Scheme 2). Therefore, X-ray crystallography was
undertaken on representative compound 26 with a view
to reveal some more discrete structural features of these
compounds.
The molecule of 26 has a butterfly shape due to the
conformation of the central 1,4,2-dithiazine ring which
is intermediate between boat and chair and to the vir-
tually coplanar arrangement of the phenyl and triazole
moieties (dihedral angle of 16.7ꢁ) stabilized by weak
intramolecular C20–H20ꢂ ꢂ ꢂN13 interaction (H20ꢂ ꢂ ꢂN13
2.35 A, <C20–H20ꢂ ꢂ ꢂN13 117ꢁ). The C–S and C–N
bond lengths [1.728(2) and 1.676(2) A, respectively] of
the sulfonamido group are slightly shorter than the
corresponding bond lengths of similar, however acyclic,
arylsulfonamides.21ꢀ23 The C3–N1 and C12–N13 bonds
of 1.316(3) and 1.305(3) A are the shortest of the tri-
azole moiety and show considerable double-bond char-
acter. In crystals the molecules of 26 form
centrosymmetric dimers via a pair of weak N–Hꢂ ꢂ ꢂN
hydrogen bonds [N14ꢂ ꢂ ꢂN10 3.249(3) A, N14–H14.
All the 5,5-dioxo[1,2,4]triazolo[2,3-b][1,4,2]benzodithi-
azines 17–29 synthesized were submitted to the US
National Cancer Institute (Bethesda, MD, USA) for in
vitro testing against a panel approximately 60 tumor cell
lines. Cell lines, derived from nine different cancer types:
leukemia, lung, colon, CNS, melanoma, ovarian, renal,
prostate and breast. The compounds were tested at five
concentrations at 10-fold dilution. A 48-h continuous
drug exposure protocol was used and sulphorhodamine
B (SRB) protein assay was used to estimate cell growth.
Details of this test system and the information which is
encoded by the activity pattern over all cell lines, have
been published.24,25 The antitumor activity of a test
compound is given by three parameters for each cell
line: GI50, molar concentration of the compound that
inhibits 50% net cell growth; TGI molar concentration

E.Pomarnacka, M.Gdaniec / Bioorg.Med.Chem.11 (2003) 1259–1267
1261
Scheme 2. Proposed mechanism of the formation of the 2-arylamino-5,5-dioxo[1,24]triazolo[2,3-b][1,4,2]benzodithiazines 17–29.
insensitive cell lines are included with the highest con-
centration tested. The discovery of compounds with
new selectivity patterns is one of the intentions of the
screening program.
The following is to be noted regarding the tumor cell
growth inhibition data with the tested compounds.
Compounds 18, 19, 23, 28 and 29 were inactive (log
GI50>ꢀ4), whereas the other compounds 17, 20, 21, 22
and 24–27 exhibited reasonable antineoplastic activity
against most of the human cell lines (Table 1). Rela-
tively highest sensitivity to the compounds described
here was found for leukemia (SR, CCRF-CEM), ovar-
ian cancer (IGROVI, OVCAR-3), CNS cancer (SF-539)
and lung cancer (HOP-92). The nature and location of
substituents essentially influence cytotoxic activity of
derivatives and differentiate sensitivity of tumor cell
lines. The presence of the nitrile group at the position 7
essentially increased the cytotoxicity, as seen in the ser-
ies of structural analogues 17, 21, 26 and 20, 24, 28
varied by R1 (CN, CH3 or COOCH3). Generally, the
most active compounds were 17, 20 and 26 (Table 2).
Different cancer cell lines of the same tumor type pos-
sessed a variable response to inhibition of growth in the
presence of the new derivatives. For example, the SR
leukemia cells were susceptible to inhibition by 17 (log
GI50=ꢀ7.67, log TGI=ꢀ6.90 and log LC50=ꢀ4.77),
whereas other leukemia cell lines (such as CCRF-CEM,
HL-60, KL-562, etc.) showed a lower level of inhibition
(log GI50 ranged from ꢀ5.70 to ꢀ5.88). The same sit-
uation has been evidenced in the case of diverse ovarian
cancer cell lines, with compound 26 acting as a potent
inhibitor against the IGROV1 line (log GI50=ꢀ7.16,
log TGI=ꢀ5.84and log LC 50=ꢀ5.32). Furthermore,
the substitution of the arylamino group at the position 2
by the electron-withdrawing chlorine atom led to inac-
tive compounds 19 and 23.
Figure 2. View of the hydrogen-bonded dimer of 26 showing short
intra- and intermolecular contacts (A) and atom labeling.
of the compound leading to total inhibition; and LC50,
molar concentration of the compound leading to 50%
net cell death. Furthermore, a mean graph midpoint
(MG_MID) is calculated for each of the mentioned
parameters, giving an averaged activity parameter over
all cell lines. For the calculation of the MG_MID,

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E.Pomarnacka, M.Gdaniec / Bioorg.Med.Chem.11 (2003) 1259–1267
Table 1. Overview of the results of the in vitro antitumor screening for compounds 17–29aꢀd
Compd
No. of the cell lines
investigated
No. of the cell lines giving positive log GI50b (M), log GTIc (M), and log LC50d (M)
log GI50b (M) log GTIc (M) log LC50d (M)
No.
Range
No.
Range
No.
Range
17
20
21
22
2458
25
26
27
59
52
53
53
58
56
55
57
59
52
53
53
ꢀ7.67 to ꢀ5.08
ꢀ6.30 to ꢀ4.79
ꢀ5.70 to ꢀ4.49
ꢀ5.77 to ꢀ4.45
ꢀ6.50 to ꢀ4.75
ꢀ5.66 to ꢀ4.21
ꢀ7.16 to ꢀ4.97
ꢀ5.93 to ꢀ4.74
58
50
48
40
40
35
54
57
ꢀ6.90 to ꢀ4.73
ꢀ5.53 to ꢀ4.28
ꢀ5.16 to ꢀ4.15
ꢀ5.36 to ꢀ4.06
ꢀ5.03 to ꢀ4.04
ꢀ5.20 to ꢀ4.02
ꢀ5.84to ꢀ4.60
ꢀ5.33 to ꢀ4.40
50
41
23
2
5
7
ꢀ5.30 to ꢀ4.18
ꢀ5.18 to ꢀ4.07
ꢀ4.47 to ꢀ4.02
ꢀ4.35 to ꢀ4.19
ꢀ4.31 to ꢀ4.07
ꢀ4.40 to ꢀ4.01
ꢀ5.32 to ꢀ4.16
ꢀ5.14to ꢀ4.07
56
55
57
52
48
aData obtained from the NCI’s in vitro disease-oriented human tumor cells screen (see Table 2 and refs 24and 25 for details). Compound 18, 19, 23,
28 and 29 were inactive.
bThe log of the molar concentration that inhibits 50% net cell growth.
cThe log of the molar concentration giving total growth inhibition.
dThe log of the molar concentration leading to 50% net cell death.
Conclusion
methanol (100 mL) was refluxed until the evolution of
MeSH had ceased (40–50 h) [CAUTION: because of
high toxicity, MeSH should be trapped in an aqueous
NaOH solution]. The precipitate was filtered off,
washed with methanol and dried.
We have therein described an efficient procedure for
obtaining derivatives of 5,5-dioxo[1,2,4]triazolo[2,3-b]
[1,4,2]benzodithiazine, a novel tricyclic ring system use-
ful as a lead structure for the design of antitumor
agents. Compounds 17 and 20 were the most potent of
all derivatives tested. At the present stage, we may infer
that the anticancer activity of the new compounds
depends on the electronic character of all substituents.
The mechanism of the antitumor activity and further
variations of the parent structure are currently being
investigated to improve both potency and selectivity
and to get more detailed information on the SAR.
In this manner, the following semicarbazides were
obtained.
1-(6-Chloro-1,1-dioxo-7-carbamoyl-1,4,2-benzodithiazin-
3-yl)-4-phenylsemicarbazide (4). 3.0 g (70%), mp 264–
265 ꢁC; IR (KBr) 3439, 3350, 3206 (NH), 1688 (CONH),
1668 (CONH2), 1650 (C¼N), 1319, 1165 (SO2) cmꢀ1
;
1H NMR (DMSO-d6) d 6.94–7.53 (m, 5H, ar.), 7.84 (s,
1H, NH), 7.94(s, 1H, H-5), 8.08 (s, 1H, H-8), 8.15 (s,
1H, NH), 8.98 (s, 1H, HN-2), 9.42 (s, 1H, HN-4), 11.37
(br.s, 1H, HN-1); 13C NMR (DMSO-d6) d 119.23.
122.95, 124.28, 129.03, 129.65, 130.15, 131.54, 133.76,
137.65, 139.20 (ar.), 154.66 (C¼N), 166.35 (CONH2),
169.73 (CONH). Anal. calcd for C15H12ClN5O4S2: C,
42.30; H, 2.83; N, 16.44. Found: C, 42.39; H, 3.01; N
16.37.
Experimental
Melting points are uncorrected and were determined on
a Buchi SMP-20 apparatus. The IR spectra were
recorded on 1600 FTIR Perkin-Elmer spectrometer as
potassium bromide pellets and frequencies are expres-
1
sed in cmꢀ1. The 13C NMR and H NMR spectra were
obtained on a Tesla BS-587 spectrometer (80 MHz)*
and Varian Gemini (200 MHz) spectrometer in dime-
thyl sulfoxide-d6. The chemical shift values d are
expressed in ppm relative to tetramethylsilane as inter-
nal standard and coupling constants (J) are in Hertz.
Abbreviations are as follows: s, singlet; d, doublet; br,
broad; m, multiplet. The analytical results for C, H,
and N were within Æ0.4% of the theoretical values.
Mass spectrum was recorded on Finningan MAT 95
(DCI) spectrometer at 70 eV. The starting 6-chloro-1,1-
dioxo-3-methylthio-1,4,2-benzodithiazines 1–3 were
obtained according to methods described previously:
1;26 2;27 3.28
1-(6-Chloro-1,1-dioxo-7-carbamoyl-1,4,2-benzodithiazin-
3-yl)-4-(4-methylphenyl)semicarbazide (5). 3.6 g (82%),
mp 275–277 ꢁC; IR (KBr) 3350, 3206 (NH), 1688
(CONH), 1655 (CONH2), 1625 (C¼N), 1310, 1160
1
(SO2) cmꢀ1; H NMR (DMSO-d6) d 2.24(s, 3H, CH ),
3
7.02–7.40 (m, 4H, ar.), 7.84 (s, 1H, NH2), 7.93 (s, 1H,
H-5), 8.07 (s, 1H, H-8), 8.15 (s, 1H, NH2), 8.92 (s, 1H,
HN-2), 9.31 (s, 1H, HN-4), 11.34 (br.s, 1H, HN-1).
Anal. calcd for C15H14ClN5O4S2: C, 43.68; H, 3.20; N,
15.92. Found: C, 43.79; H, 3.10; N 15.69.
1-(6-Chloro-1,1-dioxo-7-carbamoyl-1,4,2-benzodithiazin-
3-yl)-4-(4-chlorophenyl)semicarbazide (6). 3.6 g (78%),
mp 276–278 ꢁC; IR (KBr) 3350, 3205 (NH), 1688
(CONH), 1655 (CONH2), 1615 (C¼N), 1310, 1165
1
(SO2) cmꢀ1; H NMR (DMSO-d6) d 7.28–7.57 (m, 4H,
General procedure for preparation of 1-(6-chloro-1,1-di-
oxo-7-R1-1,4,2-benzodithiazin-3-yl)-4-(4-R2,3-R3,5-R4-
phenyl)semicarbazides (4–16). A stirred mixture of the
appropriate 3-methylthiobenzodithiazine 1–3 (10
mmol), the proper 4-arylsemicarbazide (10 mmol), and
ar.), 7.85 (s, 1H, NH2), 7.94(s, 1H, H-5), 8.07 (s, 1H, H-
8), 8.15 (s, 1H, NH2), 9.09 (s, 1H, HN-2), 9.59 (s, 1H,
HN-4), 11.38 (br.s, 1H, HN-1). Anal. calcd for
C15H11Cl2N5O4S2: C, 39.13; H, 2.40; N, 15.21. Found:
C, 39.19; H, 2.50; N 15.41.

E.Pomarnacka, M.Gdaniec / Bioorg.Med.Chem.11 (2003) 1259–1267
1263
Table 2. Inhibition of in vitro cancer cell lines by selected 8-chloro-2-arylamino-5,5-dioxo[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazines 17, 20 and 26a
Panel cell line
Response parameters: (A) log GI50b (M), (B), log TGIc (M), (C) log LC50 d (M) and MG_MID e
Compd 17
Compd 20
Compd 26
A
B
C
A
B
C
A
B
C
Leukemia
CCRF-CEM
HL-60 (TB)
K-562
MOLT-4
RPMI-8226
SR
e
e
ꢀ5.77
ꢀ5.70
ꢀ5.84
ꢀ5.88
ꢀ6.36
ꢀ7.67
ꢀ5.97
ꢀ5.77
ꢀ5.83
ꢀ5.95
nt
ꢀ5.36
ꢀ4.47
e
e
ꢀ5.60
ꢀ5.58
ꢀ5.49
ꢀ5.61
ꢀ5.75
ꢀ5.69
ꢀ5.05
ꢀ4.11
e
ꢀ5.30
ꢀ4.95
ꢀ5.39
ꢀ4.73
ꢀ6.90
ꢀ4.60
ꢀ4.71
ꢀ5.20
ꢀ4.10
e
e
e
ꢀ4.18
e
e
ꢀ4.28
ꢀ5.14
ꢀ5.33
ꢀ5.27
e
nt
nt
e
ꢀ4.10
ꢀ4.10
ꢀ4.77
ꢀ6.29
ꢀ5.47
Non-small cell lung cancer
A 549/ATCC
EKVX
HOP-62
HOP-92
NCI-H226
NCI-H23
NCI-H322M
NCI-H460
NCI-H522
ꢀ5.49
ꢀ5.35
ꢀ5.71
ꢀ6.45
ꢀ5.57
ꢀ5.75
5.57
ꢀ4.95
ꢀ4.77
ꢀ5.39
ꢀ5.24
ꢀ4.99
ꢀ5.43
ꢀ5.04
ꢀ4.95
ꢀ5.30
ꢀ4.47
ꢀ4.34
ꢀ4.79
ꢀ5.06
ꢀ5.56
nt
ꢀ4.97
ꢀ5.75
nt
ꢀ4.48
ꢀ4.67
ꢀ5.03
nt
ꢀ4.58
ꢀ5.36
nt
ꢀ4.18
ꢀ5.41
ꢀ5.19
ꢀ5.70
ꢀ5.85
ꢀ5.61
ꢀ5.76
ꢀ5.36
ꢀ5.03
—
ꢀ4.83
ꢀ4.73
ꢀ5.34
ꢀ5.43
ꢀ4.83
ꢀ5.35
ꢀ4.79
ꢀ4.64
ꢀ5.62
ꢀ4.42
ꢀ4.36
ꢀ4.94
ꢀ5.00
ꢀ4.30
ꢀ4.86
ꢀ4.40
ꢀ4.27
ꢀ5.28
ꢀ4.32
e
ꢀ5.06
e
nt
ꢀ4.40
ꢀ5.11
ꢀ4.50
ꢀ4.27
ꢀ4.64
ꢀ4.20
ꢀ4.91
nt
ꢀ5.54
ꢀ5.50
ꢀ4.91
ꢀ4.43
ꢀ5.71
ꢀ5.73
ꢀ5.34
ꢀ4.88
Colon cancer
COLO 205
HCC-2998
HCT-116
HCT-15
HT29
KM12
SW-620
e
ꢀ5.72
ꢀ5.81
ꢀ5.65
ꢀ5.79
ꢀ5.78
ꢀ5.78
ꢀ5.89
ꢀ5.43
ꢀ5.52
ꢀ5.31
ꢀ5.44
ꢀ5.24
ꢀ5.48
ꢀ5.5
ꢀ5.14
ꢀ4.96
ꢀ4.46
nt
ꢀ5.45
ꢀ5.65
ꢀ5.47
ꢀ5.80
ꢀ5.71
ꢀ5.65
nt
ꢀ4.84
ꢀ5.22
ꢀ4.90
ꢀ5.53
ꢀ5.42
ꢀ5.23
nt
ꢀ4.42
ꢀ4.67
ꢀ4.43
ꢀ5.27
ꢀ5.13
ꢀ4.66
nt
ꢀ5.24nt
ꢀ4.88
nt
ꢀ5.66
ꢀ5.60
ꢀ5.74
ꢀ5.72
ꢀ5.62
ꢀ5.20
ꢀ5.09
ꢀ5.30
ꢀ5.35
ꢀ5.31
ꢀ4.42
ꢀ4.24
ꢀ4.50
ꢀ4.93
ꢀ5.01
ꢀ5.10
e
ꢀ5.17
ꢀ5.30
Melanoma
LOX IMVI
MALME 3M
M14
SK-MEL-2
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
e
e
ꢀ5.77
ꢀ5.84
ꢀ5.63
ꢀ5.70
ꢀ5.66
ꢀ5.44
ꢀ5.85
ꢀ5.78
ꢀ5.38
ꢀ5.53
ꢀ5.23
ꢀ5.24
ꢀ5.28
ꢀ4.84
ꢀ5.55
ꢀ5.49
ꢀ5.54
ꢀ5.95
ꢀ5.25
ꢀ5.12
ꢀ5.49
ꢀ5.12
ꢀ5.84
ꢀ5.40
ꢀ5.04
ꢀ5.53
ꢀ4.55
ꢀ4.71
ꢀ4.85
ꢀ4.68
ꢀ5.48
ꢀ4.81
nt
nt
nt
ꢀ5.22
ꢀ4.61
ꢀ4.63
ꢀ4.68
ꢀ4.42
ꢀ5.25
ꢀ5.19
ꢀ5.12
ꢀ5.68
ꢀ5.36
nt
ꢀ5.53
ꢀ5.12
ꢀ4.93
ꢀ5.41
ꢀ5.13
ꢀ4.77
nt
ꢀ4.99
ꢀ4.69
ꢀ4.61
ꢀ4.87
ꢀ4.57
ꢀ4.37
nt
ꢀ4.49
ꢀ4.35
ꢀ4.28
ꢀ4.41
e
ꢀ4.31
ꢀ4.37
ꢀ4.31
ꢀ5.11
ꢀ4.31
Prostate cancer
PC-3
DU-145
ꢀ5.79
ꢀ5.77
ꢀ5.49
ꢀ5.41
ꢀ5.19
ꢀ5.05
nt
ꢀ5.50
nt
ꢀ4.90
nt
ꢀ4.41
ꢀ5.51
ꢀ5.82
ꢀ4.91
ꢀ5.48
ꢀ4.41
ꢀ5.41
CNS cancer
SF-268
SF-295
SF-539
SNB-19
SNB-75
U251
ꢀ5.59
ꢀ5.75
ꢀ5.65
ꢀ5.73
ꢀ5.46
ꢀ5.74
ꢀ5.01
ꢀ5.39
ꢀ5.34
ꢀ5.34
ꢀ4.85
ꢀ5.45
ꢀ4.48
ꢀ5.04
ꢀ5.04
ꢀ4.86
ꢀ4.33
ꢀ5.16
ꢀ5.66
ꢀ5.55
ꢀ5.72
ꢀ5.17
ꢀ5.63
ꢀ5.71
ꢀ5.26
ꢀ5.04
ꢀ5.40
ꢀ4.67
ꢀ5.12
ꢀ5.37
ꢀ4.72
ꢀ4.48
ꢀ5.08
ꢀ4.27
ꢀ4.51
ꢀ5.03
ꢀ5.70
ꢀ5.57
ꢀ5.85
ꢀ5.44
nt
ꢀ5.30
ꢀ5.06
ꢀ5.54
ꢀ4.82
nt
ꢀ4.80
ꢀ4.53
ꢀ5.23
ꢀ4.23
nt
ꢀ5.67
ꢀ5.22
ꢀ4.66
Ovarian cancer
IGROV1
ꢀ5.64
ꢀ5.95
ꢀ5.44
ꢀ5.69
ꢀ5.79
ꢀ5.32
ꢀ5.20
ꢀ5.61
ꢀ4.85
ꢀ5.42
ꢀ5.45
ꢀ4.80
ꢀ4.61
ꢀ5.27
ꢀ4.36
ꢀ5.14
ꢀ5.11
ꢀ4.39
ꢀ6.30
ꢀ5.80
ꢀ5.10
ꢀ5.55
nt
ꢀ5.77
ꢀ5.48
ꢀ4.66
ꢀ5.02
nt
ꢀ5.39
ꢀ5.15
ꢀ4.27
ꢀ4.43
nt
ꢀ7.16
ꢀ5.79
ꢀ5.84
ꢀ5.31
ꢀ5.52
ꢀ5.42
ꢀ5.84
ꢀ5.49
ꢀ5.44
ꢀ4.76
ꢀ4.96
ꢀ4.82
ꢀ5.32
ꢀ5.20
ꢀ5.03
ꢀ4.38
ꢀ4.39
ꢀ4.41
OVCAR-3
OVCAR-4
OVCAR-5
OVCAR-8
SK-OV-3
ꢀ5.18
ꢀ4.66
ꢀ4.24
Renal cancer
768-0
A498
ACHN
CAKI-1
RXF 393
SN12C
TK-10
e
e
ꢀ5.66
ꢀ5.08
ꢀ5.76
ꢀ5.85
ꢀ5.76
ꢀ5.76
ꢀ5.54
ꢀ5.78
ꢀ4.95
ꢀ4.68
ꢀ5.47
ꢀ5.57
ꢀ5.26
ꢀ5.47
ꢀ5.08
ꢀ5.44
ꢀ4.20
ꢀ4.34
ꢀ5.18
ꢀ5.28
ꢀ4.49
ꢀ5.19
ꢀ4.51
ꢀ5.09
ꢀ5.65
ꢀ4.79
ꢀ5.51
ꢀ5.49
ꢀ5.80
ꢀ5.59
nt
ꢀ5.48
ꢀ4.97
ꢀ5.94
ꢀ5.62
ꢀ5.71
ꢀ5.09
ꢀ5.54
ꢀ5.70
ꢀ4.86
ꢀ4.65
ꢀ5.63
ꢀ5.14
ꢀ5.26
ꢀ4.65
ꢀ5.05
ꢀ5.25
ꢀ4.39
ꢀ4.33
ꢀ5.31
ꢀ4.59
ꢀ4.69
ꢀ4.28
ꢀ4.53
ꢀ4.69
ꢀ4.50
ꢀ4.97
ꢀ4.90
ꢀ5.49
ꢀ5.15
nt
ꢀ4.22
ꢀ4.37
ꢀ4.41
ꢀ5.18
ꢀ4.50
nt
UO-31
ꢀ5.31
ꢀ5.36
ꢀ4.39
(continued on next page)

1264
E.Pomarnacka, M.Gdaniec / Bioorg.Med.Chem.11 (2003) 1259–1267
Table 2 (continued)
Panel cell line
Response parameters: (A) log GI50b (M), (B), log TGIc (M), (C) log LC50 d (M) and MG_MID e
Compd 17
Compd 20
Compd 26
A
B
C
A
B
C
A
B
C
Breast cancer
MCF 7
NCI/ADR-RES
MDA-MB-231/ATCC
HS 578T
MDA-MB-435
MDA-N
BT 549
T-47D
MG_MID
e
ꢀ5.58
ꢀ5.74
ꢀ5.68
ꢀ5.73
ꢀ5.76
nt
ꢀ5.61
ꢀ5.81
ꢀ5.74
ꢀ4.79
ꢀ5.45
ꢀ5.19
ꢀ5.17
ꢀ5.43
nt
ꢀ5.09
ꢀ5.19
ꢀ5.25
ꢀ5.73
ꢀ5.61
ꢀ5.51
ꢀ5.57
ꢀ5.52
nt
ꢀ5.67
ꢀ5.49
ꢀ5.54
ꢀ5.18
ꢀ5.19
ꢀ4.89
ꢀ4.80
ꢀ4.98
nt
ꢀ5.22
ꢀ4.50
ꢀ4.97
ꢀ4.53
ꢀ4.07
ꢀ5.64
ꢀ5.09
ꢀ5.45
ꢀ5.49
ꢀ5.31
ꢀ5.27
ꢀ5.87
ꢀ5.77
ꢀ5.56
ꢀ5.13
ꢀ4.60
ꢀ4.82
ꢀ4.74
ꢀ4.76
ꢀ4.72
ꢀ5.20
ꢀ5.43
ꢀ5.06
ꢀ4.53
ꢀ4.16
ꢀ5.16
ꢀ4.54
ꢀ4.32
ꢀ4.31
e
e
e
ꢀ5.10
ꢀ4.41
ꢀ4.38
ꢀ4.32
ꢀ4.57
ꢀ5.09
ꢀ4.56
nt
nt
ꢀ4.53
ꢀ4.60
e
e
ꢀ4.69
ꢀ4.44
aData obtained from the NCI’s in vitro disease-oriented human tumor cells screen (see refs. 24and 25 for details).
bThe log of the molar concentration that inhibits 50% net cell growth.
cThe log of the molar concentration giving total growth inhibition.
dThe log of the molar concentration leading to 50% net cell death. MG_MID=mean graph midpoint=arithmetical mean value for all tested cancer
cell lines. If the indicated effect was not attainable within the used concentration interval, the highest tested concentration was used for the calcu-
lation.
eThe values log TGI or log LC50 >ꢀ4.00; nt, not tested.
1-(6-Chloro-1,1-dioxo-7-carbamoyl-1,4,2-benzodithiazin-
3-yl)-4-(3,5-dimethylphenyl)semicarbazide (7). 3.1
1H, H-5), 8.0 (s, 1H, H-8), 9.05 (s, 1H, HN-2), 9.52 (s,
1H, HN-4), 11.21 (s, 1H, HN-1)*. Anal. calcd for
C15H12Cl2N4O3S2: C, 41.77; H, 2.80; N, 12.99. Found:
C, 41.85; H, 3.05; N 12.90.
g
(68%), mp 222–224 ꢁC; IR (KBr) 3445, 3310, 3210
(NH), 1688 (CONH), 1660 (CONH2), 1610 (C¼N),
1
1325, 1165 (SO2) cmꢀ1; H NMR (DMSO-d6) d 2.28 (s,
6H, 2ꢃCH3), 6.66 (s, 1H, ar.), 7.12 (brs, 2H, ar.), 7.86
(s, 1H, NH), 7.95 (s, 1H, H-5), 8.08 (s, 1H, H-8), 8.16 (s,
1H, NH), 8.93 (s, 1H, HN-2), 9.25 (s, 1H, HN-4), 11.34
(br.s, 1H, HN-1); 13C NMR (DMSO-d6) d 21.37
(2ꢃCH3), 117.0, 124.26, 124.51,129.64, 130.16, 131.58,
133.74, 137.63, 137.97, 139.03 (ar.), 154.58 (C¼N),
166.34(CONH 2), 169.78 (CONH). Anal. calcd for
C17H16ClN5O4S2: C, 44.98; H, 3.55; N, 15.42. Found:
C, 44.79; H, 3.50; N 15.63.
1-(6-Chloro-1,1-dioxo-7-methyl-1,4,2-benzodithiazin-3-
yl)-4-(3,5-dimethylphenyl)semicarbazide (11). 3.5
g
(83%), mp 246–248 ꢁC; IR (KBr) 3279, 3126 (NH), 1690
(CONH), 1620 (C¼N), 1281, 1160 (SO2) cmꢀ1
;
1H
NMR (DMSO-d6) d 2.24(s, 6H, 2 ꢃCH3), 2.45 (s, 3H,
CH3), 6.64–6.67 (m, 1H, ar.), 7.08–7.18 (m, 2H, ar.),
7.97 (s, 1H, H-5), 8.03 (s, 1H, H-8), 8.90 (s, 1H, HN-2),
9.23 (s, 1H, HN-4), 11.23 (br.s, 1H, HN-1); 13C NMR
(DMSO-d6) d 19.57 (7-CH3), 21.37 (2ꢃCH3), 116.97,
124.45, 126.59, 128.48, 130.29, 137.36, 137.74, 137.79,
137.93, 139.06 (ar.), 154.29 (C¼N), 169.94(CONH).
Anal. calcd for C17H17ClN4O3S2: C, 48.05; H, 4.03; N,
13.18. Found: C, 48.09; H, 4.15; N, 13.31.
1-(6-Chloro-1,1-dioxo-7-methyl-1,4,2-benzodithiazin-3-
yl)-4-phenylsemicarbazide (8). 3.15 g (79%), mp 216–
218 ꢁC; IR (KBr) 3324, 3284, 3218 (NH), 1695 (CONH),
1
1349, 1155 (SO2) cmꢀ1; H NMR (DMSO-d6) d 2.42 (s,
3H, 7-CH3), 6.97–7.53 (m, 5H, Ph), 7.94(s, 1H, H-5),
8.01 (s, 1H, H-8), 8.94(s, 1H, HN-2), 9.39 (s, 1H, HN-4),
11.23 (s, 1H, HN-1). Anal. calcd for C15H13ClN4O3S2:
C, 45.39; H, 3.30; N, 14.12. Found: C, 45.15; H, 3.54; N
14.26.
1-(6-Chloro-1,1-dioxo-7-methyl-1,4,2-benzodithiazin-3-
yl)-4-(3,5-dimethoxyphenyl)semicarbazide (12). 3.85 g
(83%), mp 225–226 ꢁC; IR (KBr) 3289, 3170 (NH), 1695
(CONH), 1616 (C¼N), 1346, 1150 (SO2) cmꢀ1
;
1H
NMR (DMSO-d6) d 2.44 (s, 3H, CH3), 3.70 (s, 6H,
2ꢃOCH3), 6.14–6.20 (m, 1H, ar.), 6.75 (d, J=2.3 Hz,
2H, ar.), 7.95 (s, 1H, H-5), 8.01 (s, 1H, H-8), 8.94(s, 1H,
HN-2), 9.37 (s, 1H, HN-4), 11.22 (br.s, 1H, HN-1); 13C
NMR (DMSO-d6) d 19.57 (7-CH3), 55.31 (2ꢃOCH3),
94.84, 97.39, 126.59, 127.84, 128.49, 130.27, 137.38,
137.83, 140.98, 160.78 (ar.), 154.54 (C¼N), 169.88
(CONH). Anal. calcd for C17H17ClN4O5S2: C, 44.68; H,
3.75; N, 12.26. Found: C, 44.59; H, 4.05; N, 12.21.
1-(6-Chloro-1,1-dioxo-7-methyl-1,4,2-benzodithiazin-3-
yl)-4-(4-methylphenyl)semicarbazide (9). 3.0 g (73%),
mp 225–227 ꢁC; IR (KBr) 3283, 3189 (NH), 1684
(CONH), 1320, 1152 (SO2) cmꢀ1; 1H NMR (DMSO-d6)
d 2.23 (s, 3H, CH3), 2.43 (s, 3H, 7-CH3), 7.07–7.39 (m,
4H, Ph), 7.95 (s, 1H, H-5), 8.0 (s, 1H, H-8), 8.88 (s, 1H,
HN-2), 9.27 (s, 1H, HN-4), 11.21 (s, 1H, HN-1). Anal.
calcd for C16H15ClN4O3S2: C, 46.76; H, 3.68; N, 13.65.
Found: C, 46.53; H, 3.49; N 13.74.
1-(6-Chloro-1,1-dioxo-7-methoxycarbonyl-1,4,2-benzodi-
thiazin-3-yl)-4-phenylsemicarbazide (13). 3.6 g (82%),
mp 225–227 ꢁC; IR (KBr) 3326, 3215 (NH), 1738, 1718,
1703 (CO), 1670 (CONH), 1600 (C¼N), 1325, 1165
1-(6-Chloro-1,1-dioxo-7-methyl-1,4,2-benzodithiazin-3-
yl)-4-(4-chlorophenyl)semicarbazide (10). 3.8 g (88%),
mp 237–239 ꢁC; IR (KBr) 3271, 3189 (NH), 1689
(CONH), 1313, 1152 (SO2) cmꢀ1; 1H NMR (DMSO-d6)
d 2.42 (s, 3H, 7-CH3), 7.25–7.65 (m, 4H, Ph), 7.95 (s,
(SO2) cmꢀ1 1H NMR (DMSO-d6) d 3.89 (s, 3H,
;
OCH3), 6.8–7.54(m, 5H, ar.), 8.17 (s, 1H, H-5), 8.36 (s,
1H, H-8), 9.0 (s, 1H, HN-2), 9.44 (s, 1H, HN-4), 11.46

E.Pomarnacka, M.Gdaniec / Bioorg.Med.Chem.11 (2003) 1259–1267
1265
(br.s, 1H, HN-1). Anal. calcd for C16H13ClN4O5S2: C,
43.59; H, 2.97; N, 12.70. Found: C, 45.73; H, 3.15; N,
12.92.
131.36, 132.33, 134.98, 139.91, 141.19 (ar.), 152.1, 161.51
(C¼N). Anal. calcd for C15H8ClN5O2S2: C, 46.21; H,
2.06; N, 17.96. Found: C, 46.10; H, 2.15; N, 17.70.
1-(6-Chloro-1,1-dioxo-7-methoxycarbonyl-1,4,2-benzodi-
thiazin-3-yl)-4-(4-methylphenyl)semicarbazide (14). 3.6 g
(79%), mp 224–225 ꢁC; IR (KBr) 3324, 3205 (NH),
1740, 1721 (CO), 1666 (CONH), 1605 (C¼N), 1314,
8-Chloro-2-(4-methylphenylamino)-5,5-dioxo[1,2,4]tria-
zolo[2,3-b][1,4,2]benzodithiazine-7-carbonitrile (18). 1.1 g
(27%), mp 213–214 ꢁC; IR (KBr) 3360 (NH), 2234
1
(CN), 1602 (C¼N), 1363, 1190 (SO2) cmꢀ1; H NMR
1
1165 (SO2) cmꢀ1; H NMR (DMSO-d6) d 2.24(s, 3H,
(DMSO-d6) d 2.25 (s, 3H, CH3), 7.14(d, J=8.06 Hz,
2H, ar.), 7.44 (d, J=8.06 Hz, 2H, ar.), 8.59 (s, 1H, H-9),
9.03 (s, 1H, H-6), 10.04(s, 1H, NH); 13C NMR
(DMSO-d6) d 20.63 (CH3), 113.05 (CN), 114.42, 117.41,
129.65, 130.58, 131.03, 131.33, 132.32, 134.94, 137.42,
141.19 (ar.), 152.14, 161.64 (C¼N). Anal. calcd for
C16H10ClN5O2S2: C, 47.58; H, 2.49; N, 17.34. Found:
C, 47.39; H, 2.34; N, 17.15.
CH3), 3.9 (s, 3H, OCH3), 7.05–7.42 (m, 5H, arom.), 8.18
(s, 1H, H-5), 8.37 (s, 1H, H-8), 8.94(s, 1H, HN-2), 9.32
(s, 1H, HN-4), 11.44 (br.s, 1H, HN-1). Anal. calcd for
C17H15ClN4O5S2: C, 44.88; H, 3.32; N, 12.31. Found:
C, 44.99; H, 3.15; N, 12.39.
1-(6-Chloro-1,1-dioxo-7-methoxycarbonyl-1,4,2-benzodi-
thiazin-3-yl)-4-(3,5-dimethylphenyl)semicarbazide (15).
3.3 g (70%), mp 205–207 ꢁC; IR (KBr) 3350, 3283
(NH), 1737, 1721 (CO), 1680 (CONH), 1615 (C¼N),
8-Chloro-2-(4-chlorophenylamino)-5,5-dioxo[1,2,4]tria-
zolo[2,3-b][1,4,2]benzodithiazine-7-carbonitrile (19). 1.3 g
(30%), mp 238–239 ꢁC; IR (KBr) 3383 (NH), 2233
1
1317, 1165 (SO2) cmꢀ1; H NMR (DMSO-d6) d 2.21 (s,
1
6H, 2ꢃCH3), 3.9 (s, 3H, OCH3), 6.62–6.67 (m, 1H, ar.),
7.05–7.14(m, 2H, ar.), 8.17 (s, 1H, H-5), 8.36 (s, 1H, H-
8), 8.93 (s, 1H, HN-2), 9.24 (s, 1H, HN-4), 11.42 (br.s,
1H, HN-1); 13C NMR (DMSO-d6) d 21.35 (2ꢃCH3),
53.32 (OCH3), 117.03. 124.57, 127.04, 130.2, 130.86,
134.55, 135.64, 137.99, 138.95, 139.24 (ar.), 154.56
(C¼N), 163.77 (CO), 169.4(CONH). Anal. calcd for
C18H17ClN4O5S2: C, 46.10; H, 3.65; N, 11.94. Found:
C, 46.23; H, 3.75; N, 12.12.
(CN), 1601 (C¼N), 1361, 1190 (SO2) cmꢀ1; H NMR
(DMSO-d6) d 7.40 (d, J=8.7 Hz, 2H, ar.), 7.57 (d,
J=8.7 Hz, 2H, ar.), 8.6 (s, 1H, H-9), 9.05 (s, 1H, H-6),
10.03 (s, 1H, NH); 13C NMR (DMSO-d6) d 113.07
(CN), 114.39, 118.85, 125.3, 129.15, 131.07, 131.33,
132.32, 134.96, 138.89, 141.23 (ar.), 152.16, 161.2
(C¼N). Anal. calcd for C15H7ClN5O2S2: C, 42.46; H,
1.66; N, 16.50. Found: C, 42.25; H, 1.55; N, 16.27.
8-Chloro-2-(3,5-dimethylphenylamino)-5,5-dioxo[1,2,4]-
triazolo[2,3-b][1,4,2]benzodithiazine-7-carbonitrile (20).
1.16 g (28%), mp 237–238 ꢁC; IR (KBr) 3320 (NH),
1-(6-Chloro-1,1-dioxo-7-methoxycarbonyl-1,4,2-benzodi-
thiazin-3-yl)-4-(3,5-dimethoxyphenyl)semicarbazide (16).
4g (80%), mp 178–180 ꢁC; IR (KBr) 3300, 3170 (NH),
1734(CO), 1685 (CONH), 1616 (C ¼N), 1307, 1156
1
2238 (CN), 1616 (C¼N), 1370, 1185 (SO2) cmꢀ1; H
NMR (DMSO-d6) d, 2.26 (s, 6H, 2ꢃCH3), 6.62 (s, 1H,
ar.), 7.18 (s, 2H, ar.), 8.61 (s, 1H, H-9), 9.04(s, 1H, H-
6), 10.0 (s, 1H, NH); 13C NMR (DMSO-d6) d 21.56
(2ꢃCH3), 113.07 (CN), 114.40, 115.14, 123.45, 130.99,
131.30, 132.25, 134.93, 138.2, 139.78, 141.17 (ar.), 152.0,
161.57 (C¼N). Anal. calcd for C17H12ClN5O2S2: C,
48.86; H, 2.89; N, 16.75. Found: C, 48.79; H, 2.65; N,
16.80.
(SO2) cmꢀ1 1H NMR (DMSO-d6) d 3.69 (s, 6H,
;
2ꢃOCH3), 3.9 (s, 3H, OCH3), 6.14–6.21 (m, 1H, ar.),
6.68–6.77 (m, 2H, ar.), 8.17 (s, 1H, H-5), 8.36 (s, 1H, H-
8), 8.99 (s, 1H, HN-2), 9.42 (s, 1H, HN-4), 11.44 (br.s,
1H, HN-1). Anal. calcd for C18H17ClN4O7S2: C, 43.16;
H, 3.42; N, 11.18. Found: C, 42.99; H, 3.65; N, 11.27.
General procedure for the preparation of 8-chloro-2-ary-
lamino-7-R1-5,5-dioxo[1,2,4]triazolo[2,3-b][1,4,2]benzodi-
thiazines (17–29). A stirred mixture of the appropriate
semicarbazide 4–16 (10 mmol) and phosphorus oxy-
chloride (70 mL) was refluxed for 18 h. After cooling,
the solution obtained was poured onto crashed ice (300
g) and stirred at room temperature for 10 h. The pre-
cipitated solid was collected by filtration, washed thor-
oughly with water (pH=7), dried and recrystallized
from dimethylformamide (10–15 mL).
8-Chloro-7-methyl-2-phenylamino-5,5-dioxo[1,2,4]tria-
zolo[2,3-b][1,4,2]benzodithiazine (21). 2.1 g (55%), mp
229–231 ꢁC; IR (KBr) 3375 (NH), 1601 (C¼N), 1335,
1
1165 (SO2) cmꢀ1; H NMR (CD3)2CO d 2.59 (s, 3H,
CH3), 6.96–7.74(m, 5H, ar.), 8.09 (s, 1H, H-9), 8.29 (s,
1H, H-6), 9.02 (s, 1H, NH). Anal. calcd for
C15H11ClN4O2S2: C, 47.55; H, 2.92; N, 14.79. Found:
C, 47.61; H, 2.98; N, 14.77.
8-Chloro-7-methyl-2-(4-methylphenylamino)-5,5-diox-
o[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazine (22). 2.2 g
(56%), mp 216–218 ꢁC; IR (KBr) 3335 (NH), 1609
(C¼N), 1360, 1180 (SO2) cmꢀ1; 1H NMR (DMSO-d6) d
2.25 (s, 3H, CH3Ph), 2.55 (s, 3H, 8-CH3), 7.04–7.61 (m,
4H, ar.), 8.25 (s, 1H, H-9), 8.39 (s, 1H, H-6), 9.98 (s, 1H,
NH)*. Anal. calcd for C16H13ClN4O2S2: C, 48.91; H,
3.33; N, 14.26. Found: C, 48.99; H, 3.45; N, 14.37.
In this manner, the following benzodithiazines were
obtained.
8 - Chloro - 2 - phenylamino - 5,5 - dioxo[1,2,4]triazolo[2,3 -
b][1,4,2]benzodithiazine-7-carbonitrile (17). 1.12
g
(29%), mp 215–217 ꢁC; IR (KBr) 3312 (NH), 2238 (CN),
1618 (C¼N), 1376, 1180 (SO2) cmꢀ1; 1H NMR (DMSO-
d6) d 6.98 (t, J=7.3 Hz, 1H, ar.), 7.28–7.41 (m, 2H, ar.),
7.57 (d, J=7.69 Hz, 2H, ar.), 8.62 (s, 1H, H-9), 9.06 (s,
1H, H-6), 10.17 (s, 1H, NH); 13C NMR (DMSO-d6) d
113.05 (CN), 114.4, 117.35, 121.73, 129.27, 131.06,
8-Chloro-2-(4-chlorophenylamino)-7-methyl-5,5-diox-
o[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazine (23). 2.06 g
(50%), mp 240–241 ꢁC; IR (KBr) 3359 (NH), 1604

1266
E.Pomarnacka, M.Gdaniec / Bioorg.Med.Chem.11 (2003) 1259–1267
(C¼N), 1350, 1180 (SO2) cmꢀ1; 1H NMR (DMSO-d6) d
2.55 (s, 3H, 8-CH3), 7.36–7.62 (m, 4H, ar.), 8.26 (s, 1H,
H-9), 8.39 (s, 1H, H-6), 10.28 (s, 1H, NH); MS (70 eV)
1725 (CO), 1616 (C¼N), 1370, 1185 (SO2) cmꢀ1
;
1H
NMR (DMSO-d6) d, 2.24(s, 6H, 2 ꢃCH3), 3.92 (s, 3H,
OCH3), 6.59 (s, 1H, ar.), 7.17 (s, 2H, ar.), 8.44 (s, 1H,
H-9), 8.63 (s, 1H, H-6), 9.97 (s, 1H, NH); 13C NMR
(DMSO-d6) d 21.57 (2ꢃCH3), 53.57 (OCH3), 115.13,
123.42, 128.42, 130.21, 130.50, 130.61, 132.02, 132.63,
138.2, 139.84(ar.), 152.45, 161.59 (C ¼N), 163.26 (CO).
Anal. calcd for C18H15ClN4O4S2: C, 47.94; H, 3.35; N,
12.42. Found: C, 47.99; H, 3.61; N, 12.25.
m/z:
412
(M+,
100%).
Anal.
calcd
for
C15H10Cl2N4O2S2: C, 43.59; H, 2.43; N, 13.56. Found:
C, 43.70; H, 2.55; N, 13.68.
8-Chloro-2-(3,5-dimethylphenylamino)-7-methyl-5,5-diox-
o[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazine (24). 1.8 g
(44%), mp 234–235 ꢁC; IR (KBr) 3315 (NH), 1615
(C¼N), 1365, 1180 (SO2) cmꢀ1; 1H NMR (DMSO-d6) d
2.26 (s, 6H, 2ꢃCH3), 2.55 (s, 3H, 8-CH3), 6.61 (s,1H,
ar.), 7.19 (s, 2H, ar.), 8.25 (s, 1H, H-9), 8.37 (s, 1H, H-
6), 9.94(s, 1H, NH); 13C NMR (DMSO-d6) d 19.52 (7-
CH3), 21.56 (2ꢃCH3), 115.10, 123.32, 125.85, 127.88,
129.77, 130.57, 138.15, 138.33, 139.93, 140.08 (ar.),
153.08 (C¼N), 161.56 (C¼N). Anal. calcd for
C17H15ClN4O2S2: C, 50.18; H, 3.71; N, 13.76. Found:
C, 50.23; H, 3.65; N, 13.67.
Methyl 8 - chloro - 2 - (3,5 - dimethoxyphenylamino) - 5,5-
dioxo[1,2,4]triazolo[2,3 - b][1,4,2]benzodithiazine - 7 - car-
boxylate (29). 1.6 g (33%), mp 194–196 ꢁC; IR (KBr)
3345 (NH), 1737(CO), 1612 (C¼N), 1363, 1180 (SO2)
1
cmꢀ1; H NMR (DMSO-d6) d, 3.72 (s, 6H, 2ꢃOCH3),
3.92 (s, 3H, OCH3), 6.15 (s, 1H, ar.), 6.75–6.87 (m, 2H,
ar.), 8.45 (s, 1H, H-9), 8.63 (s, 1H, H-6), 10.09 (s, 1H,
NH); 13C NMR (DMSO-d6) d 53.57 (OCH3), 55.32
(2ꢃOCH3), 93.24, 96.34, 128.44, 130.27, 130.64, 132.07,
132.67, 138.17, 141.49, 161.12 (ar.), 152.38, 161.37 (C¼N),
163.27 (CO). Anal. calcd for C18H15ClN4O6S2: C, 44.76;
H, 3.14; N, 11.60. Found: C, 44.79; H, 3.05; N, 11.52.
8-Chloro-2-(3,5-dimethoxyphenylamino)-7-methyl-5,5-di-
oxo[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazine (25). 1.8 g
(41%), mp 220–221 ꢁC; IR (KBr) 3400 (NH), 1609
(C¼N), 1354, 1150 (SO2) cmꢀ1; 1H NMR (DMSO-d6) d,
2.50 (s, 3H, 8-CH3), 3.73 (s, 6H, 2ꢃOCH3), 6.15 (t,
J=2.13 Hz, 1H, ar.), 6.80 (d, J=2.18 Hz, 2H, ar.), 8.25
(s, 1H, H-9), 8.37 (s, 1H, H-6), 10.05 (s, 1H, NH); 13C
NMR (DMSO-d6) d 19.52 (CH3), 55.31 (2ꢃOCH3),
93.14, 96.32, 125.88, 127.92, 129.82, 130.56, 138.35,
140.09, 141.57, 161.11 (ar.), 153.02 (C¼N), 161.35
(C¼N). Anal. calcd for C17H15ClN4O4S2: C, 46.52; H,
3.44; N, 12.76. Found: C, 46.60; H, 3.55; N, 12.67.
X-ray structure analysis
Crystal data for C16H11ClN4O4S2: triclinic, space
ꢀ
group P1, a=7.6220(7), b=7.8922(9), c=16.1453(10)
A, a=91.099(7), b=99.906(6), g=114.945(10)ꢁ,
V=862.89(14) A3, Z=2, dx=1.627 g cmꢀ3, T=293 K.
Data were collected for a crystal with dimensions
0.5ꢃ0.3ꢃ0.2 mm on a KumaCCD diffractometer using
graphite monochromated Mo Ka radiation. Final R
indices for 2724reflections with I >2s(I) and 289
refined parameters are: R1=0.0365, wR2=0.0914
(R1=0.0408, wR2=0.0951 for all 3026 data). Atom
labeling is shown in Figure 1. Tables of atomic coordi-
nates, bond lengths, and bond angles have been depos-
ited with the Cambridge Crystallographic Data Centre.
These tables may be obtained on request from the
Director, Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK.
Methyl 8 - chloro - 2 - phenylamino - 5,5 - dioxo[1,2,4]tria-
zolo[2,3-b][1,4,2]benzodithiazine-7-carboxylate (26). 1.45
g (34%), mp 232–233 ꢁC; IR (KBr) 3320 (NH), 1709
1
(CO), 1616 (C¼N), 1370, 1150 (SO2) cmꢀ1; H NMR
(DMSO-d6) d, 3.92 (s, 3H, OCH3), 6.97 (t, J=7.3 Hz,
1H, ar.), 7.34(t, J=7.8 Hz, 2H, ar.), 7.57 (d, J=7.9 Hz,
2H, ar.), 8.46 (s, 1H, H-9), 8.65 (s, 1H, H-6), 10.15 (s,
1H, NH); 13C NMR (DMSO-d6) d 53.55 (OCH3),
117.33, 121.68, 128.45, 129.25, 130.25, 130.61, 132.04,
132.63, 138.19, 139.95 (ar.), 152.49, 161.53 (C¼N),
163.25 (CO). Anal. calcd for C16H11ClN4O4S2: C, 45.44;
H, 2.62; N, 13.24. Found: C, 45.950; H, 2.65; N, 13.20.
Acknowledgements
This work was supported by the Polish State Committee
for Scientific Research (Grant 4P05F 007 19). We also
thank Dr. V.L. Narayanan from NCI (Bethesda, MD,
USA) for the in vitro screening. Moreover, we wish to
express our thanks to Professor F. Sca˛czewski, Depart-
ment of Chemical Drug Technology, Medical Uni-
versity of Gdansk for the valuable discussions.
Methyl 8 - chloro - 2 - (4 - methylphenylamino) - 5,5 - diox-
o1,2,4[1,2,4]triazolo[2,3-b][1,4,2]benzodithiazine-7-carbox-
ylate (27). 1.65 g (38%), mp 209–210 ꢁC; IR (KBr) 3350
(NH), 1736 (CO), 1606 (C¼N), 1366, 1165 (SO2) cmꢀ1
;
1H NMR (DMSO-d6) d, 2.26 (s, 3H, CH3), 3.94(s, 3H,
OCH3), 7.15 (d, J=8.42 Hz, 2H, ar.), 7.46 (d, J=8.42
Hz, 2H, ar.), 8.45 (s, 1H, H-9), 8.65 (s, 1H, H-6), 10.05
(s, 1H, NH); 13C NMR (DMSO-d6) d 20.62 (CH3),
53.55 (OCH3), 117.40, 128.43, 129.63, 130.25, 130.51,
130.61, 132.02, 132.61, 137.46, 138.17 (ar.), 152.51,
161.66 (C¼N), 163.26 (CO). Anal. calcd for
C17H13ClN4O4S2: C, 46.73; H, 2.99; N, 12.82. Found:
C, 46.90; H, 3.13; N, 12.83.
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