Synthesis, cytotoxicity testing, and structure-activity relationships of novel 6-chloro-7-(4-phenylimino-4h-3,1-benzoxazin-2-yl)-3-(substituted)-1,4,2- benzodithiazine 1,1-dioxides

Article abstract of DOI:10.1002/ardp.201000183

A new series of 16 6-chloro-1,1-dioxo-7-{4-[(4-R¹-phenyl)imino]- 4H-3,1-benzoxazin-2-yl}-3-(substituted amino)-1,4,2-benzodithiazines 7-22 was prepared in order to evaluate the cytotoxic activity against six human cancer cell lines. The structures of the new compounds were confirmed by IR, ¹H-, and ¹³C-NMR, elemental analysis and in the cases of 11 and 31 by X-ray crystal structure analysis. This analysis showed that contrary to our earlier report the structures contain a benzoxazine ring instead of the proposed quinazolinone ring. The bioassay indicated that the benzodithiazine derivatives 7-22 possess cancer cell growth-inhibitory properties. Some compounds showed a high level of selectivity for certain cell lines. The most active compounds 11, 12, 16, 19, 21, and 22 exhibited potency higher or comparable to cisplatin. The compounds were particularly effective in LCLC-103H and MCF-7 cell lines with IC₅₀ values of 0.49-1.60μM. Quantitative structure activity relationships (QSAR) revealed that a chloro substituent R¹ in the phenyl ring as well as the shape of the substituted amino group at R² (e.g., unsaturation is beneficial) are important for potency.

Full text of DOI:10.1002/ardp.201000183

Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
431
Full Paper
Synthesis, Cytotoxicity Testing, and Structure–Activity
Relationships of Novel 6-Chloro-7-(4-phenylimino-4H-3,1-
benzoxazin-2-yl)-3-(substituted)-1,4,2-benzodithiazine 1,1-
dioxides
Elz˙bieta Pomarnacka1, Anita Kornicka1, Anna Kuchnio1,2, Maike Heinrichs2, Renate Gru¨nert2, Maria
Gdaniec3, and Patrick J. Bednarski2
1
´
´
Department of Chemical Technology of Drugs, Medical University of Gdansk, Gdansk, Poland
2 Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Ernst-Moritz-Arndt-
University Greifswald, Greifswald, Germany
3
´
Faculty of Chemistry, A. Mickiewicz University, Poznan, Poland
A new series of 16 6-chloro-1,1-dioxo-7-{4-[(4-R1-phenyl)imino]-4H-3,1-benzoxazin-2-yl}-3-(substituted
amino)-1,4,2-benzodithiazines 7–22 was prepared in order to evaluate the cytotoxic activity against six
1
human cancer cell lines. The structures of the new compounds were confirmed by IR, H-, and 13C-
NMR, elemental analysis and in the cases of 11 and 31 by X-ray crystal structure analysis. This analysis
showed that contrary to our earlier report the structures contain a benzoxazine ring instead of the
proposed quinazolinone ring. The bioassay indicated that the benzodithiazine derivatives 7–22
possess cancer cell growth-inhibitory properties. Some compounds showed a high level of
selectivity for certain cell lines. The most active compounds 11, 12, 16, 19, 21, and 22 exhibited
potency higher or comparable to cisplatin. The compounds were particularly effective in LCLC-103H
and MCF-7 cell lines with IC50 values of 0.49–1.60 mM. Quantitative structure activity relationships
(QSAR) revealed that a chloro substituent R1 in the phenyl ring as well as the shape of the substituted
amino group at R2 (e.g., unsaturation is beneficial) are important for potency.
Keywords: 6-Chloro-7-(4-phenylimino-4H-3,1-benzoxazin-2-yl)-3-(substituted)-1,4,2-benzodithiazine 1,1-dioxides /
Cytotoxic activity / QSAR
Received: June 15, 2010; Revised: October 14, 2010; Accepted: October 15, 2010
DOI 10.1002/ardp.201000183
Introduction
anticancer agents [1–5] and potent inhibitors of HIV-1 inte-
grase (MBSAs) [6]. We also found that cyclic sulfonamide
derivatives of 2-amino-8-chloro-5,5-dioxo[1,2,4]triazolo[2,3–b]
[1,4,2]benzodithiazine (B, Fig. 1) [7, 8] or of type C–D (Fig. 1)
possess interesting in-vitro anticancer properties [9–11]. In
addition, various 1,3-benzoxazine derivatives have been
found to show versatile bioactivities such as antimicrobial,
antiviral, antifungal [12], anti-human coronavirus [13], and
anticancer activity [14].
Aryl and heteroarylsulfonyl sulfonamides are attracting
attention as anticancer agents. Our systematic studies on
the synthesis of 1,4,2-benzodithiazine-1,1-dioxides and their
subsequent transformation into N-(azolyl or azinyl)-2-mercap-
tobenzenesulfonamides A (Fig. 1) have resulted in promising
Correspondence: Patrick J. Bednarski, Department of Pharmaceutical
and Medicinal Chemistry, Institute of Pharmacy, Ernst-Moritz-Arndt-
University Greifswald, F.-L.-Jahn Str. 17, D-17487 Greifswald, Germany.
E-mail: bednarsk@uni-greifswald.de
In the search for more potent and selective agents against
cancer, we report the synthesis of 16 new compounds of type
E and the results of their in-vitro evaluation for cytotoxic
activity. The scaffold of this class of compounds consists of
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E. Pomarnacka et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
as well as with a new one 11 with the goal to establish the
more discrete structural features of these compounds.
Unexpectedly, X-ray structure analysis showed that com-
pounds are 6-chloro-7-{4-[(4-R1-phenyl)imino]-4H-3,1-benzoxa-
zin-2-yl}-3-R2-1,4,2-benzodithiazine dioxides (Figs. 2–4), and
not the quinazolinone structure we previously reported [15].
The mechanism of the reaction pathway was not investi-
gated but it can be postulated as follows. First, the reaction of
carboxamide 2 or 3 with thionyl chloride involves the initial
formation of unstable intermediate A, which with evolution
of the hydrogen chloride giving rise to formation intermedi-
ate B. In turn, the latter intermediate subsequently under-
goes an intramolecular cyclocondensation with evolution
molecule of the sulfur dioxide to afford the final products
4–6. Carboxamides 2 or 3 did not undergo the intramolecular
cyclization (Scheme 1) in the presence of dehydrating agents
such as phosphorous oxychloride or thionyl chloride to
obtain quinazolinone C [18–20].
Figure 1. Structures of A–E.
two moieties: 1,1-Dioxo-1,4,2-benzodithiazine and 1,3-benz-
oxazine. The objective of this drug-design approach was to
merge these two moieties to enhance their activity against
cancer cells. Our previous studies with this class of com-
pounds showed that electronic character of the benzodithi-
azine ring system substituent at position-3 was an important
factor influencing cytotoxicity [15]. However, in this previous
publication we reported that the compounds were quinazo-
linone derivates. Based on X-ray crystal structure analysis of
two representative compounds we now correct the structures
to be benzoxazine derivatives. Herein, the effects of further
structural modifications on antitumor activity were explored
within two structural domains: The benzodithiazine ring
(substituent R2) and substituents of benzoxazine moiety
(R1-phenyl). A correlation between the structures of these
derivatives and the potency to inhibit the growth of cancer
cells was investigated by using quantitative structure activity
relationship (QSAR) methods.
Furthermore, nucleophilic displacement of the 3-methyl-
thiol group of 4–6 by the appropriate amine in boiling meth-
anol proceeded with elimination of methyl mercaptane,
leading to the target benzodithiazines 7–22 in 27-78% yields
(Scheme 2). All final products were characterized by IR and
NMR spectroscopy as detailed in the experimental section.
Elemental analyses were in accordance with the proposed
structures.
Molecules 11 and 31 [15] with their labeling scheme are
shown in Figures 2 and 3. Bonding geometries of the benzox-
azin-4-imine and 1,4,2-benzodithiazin-3-amine 1,1-dioxide
units are similar to those found in previously reported struc-
tures [10, 11],[21–24]. Bond lengths indicate a double bond
˚
character at C14-N19 [1.274(2) and 1.254(6) A] and C16-N24
˚
[1.262(3) and 1.257(6) A], a relevant degree of single bond for
˚
C25-N24 [1.417(3) and 1.426(6) A] and a strong conjugation in
Results and discussion
the amidine N3-C3-N31 fragment with the C–N bond lengths
˚
in the range 1.299(7) to 1.320(8) A.
Chemistry
The analogous parts for the two molecules have very
similar conformations as shown in Fig. 4, where superposi-
tion of the molecular structures of 11 and 31 is presented.
A 1,1-dioxo-1,4,2-dithiazine ring with the lone pairs of
electrons on the S atom is known to prefer the boat confor-
mation [25] and this conformation is adopted by this ring in
both molecules, leading to their butterfly shape. The central
part that comprises a 3,1-benzoxazine system and the frag-
ment of 1,4,2-benzodithiazine unit, consisting of the benzene
ring and S substituent atoms, is virtually planar with dihe-
dral angles between the two parts being 3.6 and 6.18 in 11 and
31, respectively.
The previously described methods were employed for the
synthesis of 6-chloro-3-methylthio-1,1-dioxo-1,4,2-benzodi-
thiazin-7-carbonyl chloride 1 [16, 17]. The reaction of 1 with
the appropriate 2-aminobenzanilide was carried out in boil-
ing toluene in the presence of pyridine and afforded the
expected N-[2-(phenylcarbamoyl)phenyl]-6-chloro-1,1-dioxo-3-
methylthio-1,4,2-benzodithiazin-7-carboxamide 2–3 in 80%
yield. Treatment of 2–3 with an excess of thionyl chloride
under reflux gave rise to the novel 6-chloro-7-{4-[(4-R1-phenyl)-
imino]-4H-3,1-benzoxazin-2-yl}-3-methylthio-1,4,2-benzodi-
thiazine 1,1-dioxides 4, 5, and 6 [15].
The spectroscopic data do not allow straightforward dis-
crimination between the quinazolone structure and alterna-
tive benzoxazine. Therefore, X-ray crystallography was
undertaken with a previously described compound 31 [15]
Biology
A microtiter based assay based on the staining of adherent
cells with crystal violet was used to quantify the antiprolifer-
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Synthesis, Cytotoxicity Testing, and SAR
433
Scheme 1. Proposed mechanism of the formation of benzoxazines 4–6.
ative potential of the new compounds on human cancer cell
lines. Details of this test have been published elsewhere [26, 27].
Primary screening of compounds 7–22 for antiproliferative
activity took place on three human cancer cell lines: A-427,
DAN-G and LCLC-103. All compounds showed inhibition of
cell growth by more than 50% at 20 mM in one or more of the
cell lines. Secondary screening to determine potency was
performed on a panel of 6 human cancer cell lines: RT-4
(urinary bladder transitional cell cancer), 5637 (urinary blad-
der cancer), DAN-G (pancreas cancer), LCLC-103H (large cell
lung cancer), A-427 (lung cancer), and MCF-7 (breast cancer).
Table 1 lists the average IC50 values calculated from the dose-
response data obtained from three independent exper-
iments. The IC50 is the concentration required to inhibit cell
growth by 50% compared to the untreated control over a 96 h
treatment period [26].
lead to further increases in potency. In the series of deriva-
tives 7–22, the compounds differ in a substituent at the
position 3 of the benzodithiazine scaffold and in substitution
in the position 4 of the phenyl attached to the benzoxazine
moiety (chlorine, hydrogen or methyl group).
Based to the substituent at position 3 (R2), compounds can
be divided into three groups: 9–11 possessing an aliphatic
chain, 12–22 with a pyridine moiety and 7–8 with the mor-
pholine entity. The cytotoxicity of compounds with the
morpholine moiety is much lower than of the other
benzodithiazines, although their selectivity towards the
5637 cell line is apparent. The most active group appears
to be those with pyridine substituent. However, the mean
IC50 value of the compound 11 with allylamino group is
lower comparable to pyridine substituted compounds 12,
16, and 21.
The present results show that further structural modifi-
cation of earlier tested benzodithiazine derivatives [15] can
A comparison with activity of anticancer-agent cisplatin
indicates that benzodithiazines 7–22 possess very good cell
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E. Pomarnacka et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
Scheme 2. Synthesis of 6-chloro-7-(4-phenylimino-4H-3,1-benzoxazin-2-yl)-3-(substituted)-1,4,2-benzodithiazine dioxides 7–31.
growth inhibitory properties. The values of the IC50 were
taken from a previously published study [26] conducted in
analogous conditions to our assay. In general these results
show the greatest similarities in activity of tested benzodi-
thiazines to the alkylating agents like cisplatin and DACH-Pt.
The LCLC-103H cell line is the most sensitive of the six cell
lines. In this cell line some of the compounds showed similar
(16, 19, and 21) or even greater (10–13 and 22) potency com-
pared to cisplatin. Moreover, the RT-4 cell line was susceptible
to cell growth inhibition by 12 < 19 < 22 < 11 < 14 < 16,
which was similar or greater than cisplatin in the case of
compounds 13, 21, and 18.
Quantitative structure activity relationship studies
QSAR are frequently used in medicinal chemistry to estab-
lish a predictive relationship between structure and potency
[28]. In search of possible QSAR with our data, multiple
regression analysis was performed with 18 quantitative
descriptors for the amines at R2 and two indicator variables
for either a chlorine atom or a methyl group at R1 (see Table
S1, Supplementary Material). The dependent variable was
the –log of the IC50 values. The compounds used in the QSAR
analysis included the 16 compounds described in this work
as well as 8 compounds, 23–30 (Scheme 2) reported in an
earlier study [15]. The range in the IC50 values for the
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Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
Synthesis, Cytotoxicity Testing, and SAR
435
Figure 2. View of the molecular structure of 11 with the DMSO
solvent molecule. Displacement ellipsoids are drawn at the 50%
probability level. Disorder of the allyl group is not shown.
Figure 3. View of the molecular structure of 13 [15] with the
isopropanol solvent molecule. Displacement ellipsoids are drawn
at the 50% probability level. Disorder of the phenylethylene group
is not shown.
Figure 4. Superposition of the molecules 1 and 13 [15] (only the
˚
fitted atoms are labeled; r.m.s. 0.054 A).
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Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
24 compounds was ca. 20-fold in the RT-4, DAN-G and the
MCF-7 lines, 12-fold in the LCLC-103H line and less than 6-
fold in the remaining two lines. Both the IC50 values for the
individual cell lines as well as the average IC50 values over
identified as having a positive influence while in the three
parameter equation the kappa shape index, order 1 (KSI-1)
[29] has a positive effect while too large a molar volume (MV)
is detrimental.
ꢁlogðIC50Þall lines ¼ 0:024ðꢀ0:006Þ USA þ 0:306ðꢀ0:091Þ ICl þ 4:336ðꢀ0:249Þ
n ¼ 24 rCV2 ¼ 0:400 r ¼ 0:768 s ¼ 0:252 F ¼ 15:139
(1)
(2)
ꢁlogðIC50Þall lines ¼ 0:442ðꢀ0:094ÞKSI-1 ꢁ 0:024ðꢀ0:008ÞMV þ 0:367ðꢀ0:074ÞICl þ 4:811ðꢀ0:175Þ
n ¼ 24 rCV2 ¼ 0:585 r ¼ 0:861 s ¼ 0:282 F ¼ 19:082
all six lines where included in the analysis.
In the cases of three individual cell lines where significant
correlations where found, the unsaturated surface area of the
group at R2 and the presence of a chlorine atom at R1 were
again important determinates for activity. This was particu-
larly apparent when the data was fitted to the two best
parameters, as in the cases of Eqs. (3), (5), and (7). In the cases
of the cell lines LCLC-104H and RT-4, inclusion of a second
indicator variable for the methyl group at R1 improved the
correlation considerably (see Eqs. (4) and (6)). This was not
unexpected because the methyl is bioisoteric with Cl.
The best correlations were found with the data from the
averaged IC50 values for all six lines, where the IC50 values
differed by a factor of maximal 24-fold (see Table S1).
Significant correlations where also found with three individ-
ual cell lines (LCLC-104H, RT-4, and MCF-7). The remaining
three cell lines (DAN-G, A-427, and 5637) gave much poorer
correlations, which were in many cases no longer significant
(data not shown). Cross-validation of the data was performed
by the leave-one-out procedure and is reported as the cross-
ꢁLlgðIC50ÞLCLC ¼ 0:011ðꢀ0:003ÞUSA þ 0:568ðꢀ0:135Þ ICl þ 5:048ðꢀ0:131Þ
n ¼ 24 rCV2 ¼ 0:419 r ¼ 0:747 s ¼ 0:350 F ¼ 13:23
(3)
(4)
(5)
(6)
ꢁlogðIC50ÞLCLC ¼ 0:010ðꢀ0:003ÞUSA þ 0:718ðꢀ0:123ÞICl þ 0:462ðꢀ0:148ÞICH3 þ 4:925ðꢀ0:117Þ
n ¼ 24 rCV2 ¼ 0:597 r ¼ 0:838 s ¼ 0:393 F ¼ 15:72
ꢁlogðIC50ÞRT4¼ 0:013ðꢀ0:003ÞUSA þ 0:4544ðꢀ0:119ÞIClþ4:912ðꢀ0:115Þ
n ¼ 24 rCV2 ¼ 0:502 r ¼ 0:767 s ¼ 0:327 F ¼ 15:01
ꢁlogðIC50ÞRT4 ¼ 0:012ðꢀ0:003ÞUSA þ 0:575ðꢀ0:112ÞIClþ0:371ðꢀ0:135ÞICH3þ4:813ðꢀ0:106Þ
n ¼ 24 rCV2 ¼ 0:757 r ¼ 0:838 s ¼ 0:357 F ¼ 15:67
validated squared correlation coefficient rCV2.
In the case of the MCF-7 cell line, the inclusion of the three
best parameters in the regression equations still indicated
that the shape of the substituent at R2 is important but now
the saturated surface area (SSA) is detrimental while the
water accessible surface area (WASA) is beneficial to activity
(Eq. (8)). The result that the saturated surface area is detri-
mental is consistent with the regression equations that
showed the unsaturated surface area to be beneficial because
the one parameter is the opposite of the other.
Equations (1) and (2) show the results of the multiple
regression analysis for two and three best variables for the
average IC50 values of all lines. The single most important
parameter contributing to good activity is the presence of a
chlorine atom at position R1 of the phenyl ring, as evidence
by the indicator variable ICl in both equations. The shape of
the substituent at R2 also appears to influence activity; in the
two variable equation the unsaturated surface area (USA) was
ꢁlogðIC50ÞMCF7 ¼ 0:011ðꢀ0:003ÞUSA þ 0:370ðꢀ0:108ÞIClþ5:011ðꢀ0:105Þ
n ¼ 24 rCV2 ¼ 0:370 r ¼ 0:755 s ¼ 0:287 F ¼ 13:90
(7)
(8)
ꢁlogðIC50ÞMCF7 ¼ ꢁ0:013ðꢀ0:003ÞSSA þ 0:012ðꢀ0:002ÞWASA þ 0:316ðꢀ0:088ÞIClþ4:925ðꢀ0:244Þ
n ¼ 24 rCV2 ¼ 0:610 r ¼ 0:855 s ¼ 0:325 F ¼ 18:10
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Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
Synthesis, Cytotoxicity Testing, and SAR
437
(s, 1H, H-5 benzodit.), 8.36 (s, 1H, H-8 benzodit.), 10.40 (s, 1H, NH),
11.09 (s, 1H, NH) ppm.
Conclusion
The above data show the usefulness of uniting benzoxazine
and benzodithiazine moieties to build a scaffold with good
cytotoxic activity. It can be concluded that the shape (e.g.,
unsaturation) of the substituents R2 of the benzodithiazine
ring system as well as a chlorine or methyl group in the
phenyl ring at R1 positively influence the cytotoxicity
potency of the compounds. Further structural modification
along the lines of the QSAR may help to further increase the
potency of this interesting new class of cytotoxic compounds.
N-[2-(4-chlorophenylcarbamoyl)phenyl]-6-chloro-1,1-
dioxo-3-methylthio-1,4,2-benzodithiazin-7-carboxamide 3
Starting from 2-amino-N-(4-chlorophenyl)benzamide (2.71g);
yield: 4.4 g (80%); mp 242–2448C. IR (KBr, cmꢁ1) 3276 (NH),
1666 (CO), 1628, 1603 (C N), 1350, 1165 (SO2). 1H-NMR
–
–
(200 MHz, DMSO-d6): d 2.72 (s, 3H, SCH3), 7.28–7.45 (m, 3H,
aromat.), 7.54–7.82 (m, 4H, aromat.), 7.93 (d, J ¼ 7.7 Hz, 1H,
aromat.), 8.15 (s, 1H, H-5 benzodit.), 8.32 (s, 1H, H-8 benzodit.),
10.58 (s, 1H, NH), 10.94 (s, 1H, NH) ppm.
6-Chloro -7-{4-[(4-R1-phenyl)imino]-4H-3,1-benzoxazin-
2-yl}-3-methylthio-1,4,2-benzodithiazine
1,1-dioxides 4–5
A mixture of carboxamide 2 or 3 (10 mmol) and thionyl chloride
(50 mL) was refluxed for 30 h. The thionyl chloride was distilled
off (808C) then to the residue toluene was added (2 ꢂ 40 mL) and
distilled off (1118C). The dry residue was recrystallized from
anhydrous toluene (100 mL) to give 4 or 5.
Experimental
Chemistry
General
Melting points are uncorrected and were determined on a Bu¨chi
SMP-20 apparatus (Bu¨chi Labortechnik, Flawil, Switzerland). The
IR spectra were recorded on 1600 FTIR Perkin Elmer (Perkin
Elmer, Norwalk, CT, USA) spectrometer by using potassium bro-
mide pellets and frequencies were expressed in cmꢁ1. The 13C–
and 1H-NMR spectra were obtained on a Varian Gemini (50 MHz
and 200 MHz) or Varian Unity Plus (125 MHz and 500 MHz)
spectrometers (Varian Inc., Palo Alto, CA, USA). The chemical
shift values d were expressed in ppm relative to the residual
solvent signal at 2.50 or 7.26 ppm and 39.5 or 77 ppm, respect-
ively. The analytical results for C, H, and N were within ꢀ0.4% of
the theoretical values and results are reported in Table S2
(Supplementary Material). The starting 6-chloro-3-methylthio-
1,1-dioxo-1,4,2-benzodithiazin-7-carboxylic acid [16], 6-chloro-3-
methylthio-1,1-dioxo-1,4,2-benzodithiazin-7-carbonyl chloride 1
[17], N-[2-(phenylcarbamoyl)phenyl]-6-chloro-1,1-dioxo-3-methyl-
thio-1,4,2-benzodithiazin-7-carboxamide [15], and 6-chloro-1,1-
dioxo-3-methylthio-7-[4-(phenylimino)-4H-3,1-benzoxazin-2-yl]-
1,4,2-benzodithiazine 6 [15] were obtained by the previously
described methods.
6-Chloro-1,1-dioxo-7-{4-[(4-methylphenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-methylthio-1,4,2-benzodithiazine 4
Starting from 2 (5.32 g); yield: 1.3 g (25.3%); mp 256–2588C. IR
1
(KBr, cmꢁ1) 1670 (N C), 1630, 1605 (C N), 1345, 1170 (SO ). H-
–
–
–
–
2
NMR (500 MHz, CDCl3): d 2.36 (s, 3H, PhCH3), 2.74 (s, 3H, SCH3),
7.03 (d, J ¼ 8 Hz, 2H, PhCH3), 7.09 (d, J ¼ 8 Hz, 2H, PhCH3), 7.48
(s, 1H, H-5 benzodit.), 7.59 (t, J ¼ 7.3 Hz, 1H, aromat.), 7.64 (d,
J ¼ 8.3 Hz, 1H, aromat.), 7.76 (t, J ¼ 7.3 Hz, 1H, aromat.), 8.46 (d,
J ¼ 7.8 Hz, 1H, aromat.), 8.66 (s, 1H, H-8 benzodit.) ppm; 13C-NMR
(500 MHz, CDCl3): d 16.69 (SCH3), 20.97 (CH3), 119.0, 122.58,
125.86, 127.28, 127.56, 127.64, 128.28, 129.13, 129.47, 129.90
(two overlapping signals), 129.95, 130.51, 131.91, 134.71, 135.45,
–
–
138.04, 142.35 (aromat.), 146.97, 152.22 (C N), 179.91 (N C)
ppm.
–
–
6-Chloro-1,1-dioxo-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-methylthio-1,4,2-benzodithiazine 5
Starting from 3 (5.52 g); yield: 3.8 g (70%); mp 228–2308C. IR (KBr,
N-[2-(R1-Phenylcarbamoyl)phenyl]-6-chloro-1,1-dioxo-3-
methylthio-1,4,2-benzodithiazin-7-carboxamides 2, 3
To a suspension of compound 1 (3.42 g, 10 mmol) and 2-amino-N-
(p-tolyl or 4-chlorophenyl)benzamide (11 mmol) in anhydrous
toluene (120 mL), pyridine (0.8 mL, 10 mmol) in anhydrous
toluene (50 mL) was added. The reaction mixture was stirred
at reflux for 48 h and then left overnight at room temperature.
The precipitate was filtered off, washed with toluene (5 mL),
dried and suspended in 0.5% aqueous K2CO3 (200 mL). The mix-
ture was stirred for 1 h, filtered off, washed successively with
water (2 ꢂ 50 mL), methanol (20 mL), and dried. In this manner,
the following compounds were obtained.
cmꢁ1) 1670 (N C), 1630, 1605 (C N), 1345, 1170 (SO ). 1H-NMR
–
–
–
–
2
(200 MHz, CDCl3): d 2.72 (s, 3H, SCH3), 7.09 (d, J ¼ 8.7 Hz, 2H,
PhCl), 7.32 (d, J ¼ 8.7 Hz, 2H, PhCl), 7.48 (s, 1H, H-5 benzodit.),
7.52–7.63 (m, 2H, aromat.), 7.72 (ddd, J ¼ 1.5 Hz, J ¼ 8.2 Hz,
J ¼ 8.5 Hz, 1H, aromat.), 8.31 (ddd, J ¼ 7.7 Hz, J ¼ 8.8 Hz, J ¼ 1.2 Hz,
1H, aromat.), 8.64 (s, 1H, H-8 benzodit.) ppm. 13C-NMR (200 MHz,
CDCl3): d 16.94 (SCH3), 119.66, 124.14 (two overlapping signals),
127.28, 127.56, 127.88, 129.25, 129.47 (two overlapping signals),
129.83, 130.07, 130.17, 130.27, 134.72, 134.79, 134.96, 138.0,
–
–
142.47 (aromat.), 151.57, 152.86 (C N), 180.07 (N C) ppm.
–
–
General procedure for preparation of 6-chloro-1,1-dioxo-7-
{4-[(4-R1-phenyl)imino]-4H-3,1-benzoxazin-2-yl}-3-R2-1,4, 2-
benzodithiazines 7–22
A mixture of the corresponding benzodithiazine 4–6 (1 mmol)
and the appropriate amine (1.1 mmol) in dry methanol (20 mL)
was stirred at room temperature for 10 h and then refluxed until
the evolution of MeSH had ceased (20–40 h) [Caution: because of
high toxicity, MeSH should be trapped in an aqueous NaOH
N-[2-(4-methylphenylcarbamoyl)phenyl]-6-chloro-1,1-
dioxo-3-methylthio-1,4,2-benzodithiazin-7-carboxamide 2
Starting from 2-amino-N-p-tolylbenzamide (2.48 g); yield: 4.5 g
(85%); mp 268–2708C. IR (KBr, cmꢁ1) 3267 (NH), 1650 (CONH),
1
1600 (C N), 1335, 1170 (SO ). H-NMR (200 MHz, DMSO-d ): d 2.27
–
–
2
6
(s, 3H, CH3Ph), 2.74 (s, 3H, CH3S), 7.13 (d, J ¼ 8.4 Hz, 2H, aromat.),
7.37 (t, J ¼ 7.3 Hz, 1H, aromat.), 7.54–7.68 (m, 3H, aromat.), 7.79
(d, J ¼ 7.3 Hz, 1H, aromat.), 8.04 (d, J ¼ 8.1 Hz, 1H, aromat.), 8.17
ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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438
E. Pomarnacka et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
solution]. The precipitate was filtered off, washed successively
with methanol (5 mL), chloroform (5 mL), and dried. In this
manner, the following compounds were obtained:
3-Allylamino-6-chloro-1,1-dioxo-7-
{4-[(4-chlorophenyl)imino]-4H-3,1-benzoxazin-2-yl}-1,4,2-
benzodithiazine 11
Starting from 5 (0.53 g) and allylamine (0.07 g); yield: 0.28 g (52%);
mp 235–2368C. IR (KBr, cmꢁ1) 3235 (NH), 1679 (N C), 1630 (C N),
–
–
6-Chloro-1,1-dioxo-7-{4-[(4-methylphenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-morpholino-1,4,2-benzodithiazine 7
Starting from 4 (0.51 g) and morpholine (0.096 g); yield: 0.29 g
–
–
4.02 (d,
1315, 1150 (SO2). 1H-NMR (200 MHz, DMSO-d6):
d
J ¼ 5.04 Hz, 2H, NCH2), 5.20 (ddd, J ¼ 3.7 Hz, J ¼ 6.4 Hz,
J ¼ 12.2 Hz, 2H, ¼CH2), 5.75–5.95 (m, 1H, CH¼ ), 7.22 (d,
J ¼ 8.5 Hz, 2H, PhCl), 7.36 (d, J ¼ 8.5 Hz, 2H, PhCl), 7.53–7.67
(m, 2H, aromat.), 7.8 (t, J ¼ 7.3 Hz, 1H, aromat.), 8.08 (s, 1H, H-5
benzodit.), 8.22 (d, J ¼ 7.3 Hz, 1H, aromat), 8.40 (s, 1H, H-8 benzo-
dit.), 10.05 (s, 1H, NH) ppm. 13C-NMR (DMSO-d6): d 45.69 (NHCH2),
117.61 (¼CH2), 119.26, 124.28 (two overlapping signals), 126.42,
127.23, 127.56, 128.32, 128.94 (two overlapping signals), 129.80,
130.16, 130.53, 131.62, 132.74, 133.71, 134.74, 135.35 142.15 (aro-
(53%); mp 276–2788C. IR (KBr, cmꢁ1) 1673 (N C), 1630 (C N),
–
–
–
–
1320, 1160 (SO2). 1H-NMR (200 MHz, CDCl3): d 2.33 (s, 3H, CH3),
3.62–4.05 (m, 8H, 4 ꢂ CH2), 6.95–7.10 (m, 2H, PhCH3), 7.18–7.31
(m, 2H, PhCH3), 7.49 (s, 1H, H-5 benzodit.), 7.50–7.80 (m, 3H,
aromat.), 8.39 (d, J ¼ 7.7Hz, 1H, H-5 aromat.), 8.62 (s, 1H, H-8
benzodit.) ppm.
–
–
mat.), 144.33 (CH¼ ), 146.17, 152.48 (C N), 161.93 (N C) ppm.
6-Chloro-1,1-dioxo-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-morpholino-1,4,2-benzodithiazine 8
Starting from 5 (0.53 g) and morpholine (0.096 g); yield: 0.3 g
–
–
6-Chloro-1,1-dioxo-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[(3-pyridylmethyl)amino]-1,4,2-
benzodithiazine 12
(52.6%); mp 245–2478C. IR (KBr, cmꢁ1) 1665 (N C), 1625 (C N),
–
–
–
–
1310, 1160 (SO2). 1H-NMR (200 MHz, CDCl3): d 3.53–4.1 (m, 8H,
4 ꢂ CH2), 7.11 (d, J ¼ 8.5 Hz, 2H, PhCl), 7.31 (d, J ¼ 8.5 Hz, 2H,
PhCl), 7.52 (s, 1H, H-5 benzodit.), 7.47–7.62 (m, 2H, aromat.),
7.67–7.76 (m, 1H, aromat.), 8.33 (d, J ¼ 7.7 Hz, 1H, aromat.),
8.61 (s, 1H, H-8 benzodit.) ppm.
Starting from 5 (0.53 g) and 3-(aminomethyl)pyridine (0.12 g);
yield: 0.46 g (78%), mp 242–2448C. IR (KBr, cmꢁ1) 3180, 3105 (NH),
1665 (N C), 1625 (C N), 1320, 1160 (SO ). 1H-NMR (200 MHz,
–
–
–
–
2
DMSO-d6): d 4.64 (s, 2H, NCH2), 7.22 (d, J ¼ 8.6 Hz, 2H, PhCl), 7.32–
7.46 (m, 3H, PhCl and H-5 pyrid.), 7.55–7.67 (m, 2H, H-4 pyrid. and
aromat.), 7.71–7.87 (m, 2H, aromat.), 8.1 (s, 1H, H-5 benzodit.),
8.22 (d, J ¼ 7.0 Hz, 1H, aromat), 8.41 (s, 1H, H-8 benzodit.), 8.51
(d,d, J ¼ 4.7 Hz, J ¼ 1.5 Hz, 1H, H-6 pyrid.), 8.57 (d, J ¼ 1.8 Hz,
1H, H-2 pyrid.), 10.36 (s,1H, NH) ppm. 13C-NMR (DMSO-d6): d 44.55
(NCH2), 119.26, 124.28 (two overlapping signals), 127.23 127.62,
128.32, 128.94 (two overlapping signals), 129.81, 130.21, 130.59,
131.52, 132.48, 133.67, 134.74, 135.42, 142.14, 144.33 (aromat.),
123.92, 126.43 (C-3 and 5 pyrid.), 135.96 (C-4 pyrid), 149.12,
6-Chloro-1,1-dioxo-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-isopropylamino-1,4,2-
benzodithiazine 9
Starting from 5 (0.53 g) and 2-aminopropane (0.11 g, 18 mmol);
yield: 0.22 g (40%); mp 284–2858C. IR (KBr, cmꢁ1) 3240 (NH), 1675
(N C), 1625 (C N), 1305, 1150 (SO ). 1H-NMR (200 MHz, DMSO-
–
–
–
–
2
d6): d 1.18 (d, J ¼ 6.6 Hz, 6H, 2 ꢂ CH3), 4.04–4.21 (m, 1H, CH), 7.23
(d, J ¼ 8.5 Hz, 2H, PhCl), 7.36 (d, J ¼ 8.5 Hz, 2H, PhCl), 7.56–7.68
(m, 2H, aromat.), 7.76–7.86 (m, 1H, aromat.), 8.07 (s, 1H, H-5
benzodit.), 8.23 (d, J ¼ 7.9 Hz, 1H, aromat.), 8.39 (s, 1H, H-8
benzodit.), 9.77 (s,1H, NH) ppm. 13C-NMR (50 MHz, DMSO-d6): d
21.71 (2C, 2 ꢂ CH3), 46.45 (CH), 119.26, 124.29 (two overlapping
signals), 126.43, 127.23, 127.51, 128.32, 128.94 (two overlapping
signals), 129.80, 130.09, 130.52, 131.78, 133.87, 134.75, 135.29,
–
–
–
–
149.46 (C-2 and 6 pyrid.), 146.16, 152.47 (C N), 162.35 (N C) ppm.
6-Chloro-1,1-dioxo-7-{4-[(4-methylphenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[(3-pyridylmethyl)amino]-1,4,2-
benzodithiazine 13
Starting from 4 (0.51 g) and 3-(aminomethyl)pyridine (0.12 g);
yield: 0.29 g (52%); mp 210–2128C. IR (KBr, cmꢁ1) 3180 (NH), 1668
–
–
142.16, 144.33 (18C, aromat.), 146.19, 152.51 (C N), 160.67 (N C)
ppm.
(N C), 1628, 1603 (C N), 1312, 1160 (SO ). 1H-NMR (500 MHz,
–
–
–
–
–
–
2
DMSO-d6): d 2.28 (s, 3H, CH3), 4.65 (s, 2H, NCH2), 7.09–7.15 (m, 2H,
aromat.), 7.21 (d, J ¼ 8.3 Hz, 2H, aromat.), 7.40 (dd,
J ¼ 4.9 Hz, J ¼ 7.8 Hz, 1H, H-5 pyrid.), 7.60 (d, J ¼ 7.8 Hz, 2H,
aromat.), 7.75 (d, J ¼ 7.8 Hz, 1H, H-4 pyrid.), 7.85 (t, J ¼ 7.8 Hz,
1H, aromat.), 8.1 (s, 1H, H-5 benzodit.), 8.29 (dd,
J ¼ 1.0 Hz, J ¼ 8.3 Hz, 1H, aromat), 8.40 (s, 1H, H-8 benzodit.),
8.51 (d, J ¼ 4.7 Hz, 1H, H-6 pyrid.), 8.57 (d, J ¼ 1.9 Hz, 1H, H-2
pyrid.), 10.36 (s,1H, NH) ppm. 13C-NMR (DMSO-d6): d 20.9 (CH3),
44.96 (NCH2), 119.26, 125.7, 127.04, 127.74, 127.93, 128.89,
130.36, 130.42, 130.48, 131.08, 131.99, 132.92, 134.24, 135.40,
135.46, 135.88, 140.75, 142.55 (aromat.), 123.46, 124.38, (C-3 and
5 pyrid.), 136.40 (C-4 pyrid), 149.56, 149.90 (C-2 and 6 pyrid.),
6-Chloro-1,1-dioxo-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-(3-hydroxypropylamino)-1,4,2-
benzodithiazine 10
Starting from 5 (0.53 g) and 3-amino-1-propanol (0.083 g); yield:
0.15 g (27%); mp 210–2118C. IR (KBr, cmꢁ1) 3500, 3360 (NH, OH),
1670 (N C), 1625 (C N), 1320, 1150 (SO ). 1H-NMR (200 MHz,
–
–
–
–
2
DMSO-d6): d 1.69 (q, J ¼ 6.6 Hz, 2H, CH2), 3.36–3.54 (m, 4H, CH2N,
CH2OH), 4.57 (t, J ¼ 4.8 Hz, 1H, OH), 7.22 (d, J ¼ 8.7 Hz, 2H, PhCl),
7.36 (d, J ¼ 8.7 Hz, 2H, PhCl), 7.54–7.69 (m, 2H, aromat.), 7.74–
7.86 (m, 1H, aromat.), 8.07 (s, 1H, H-5 benzodit.), 8.22 (d,
J ¼ 7.0 Hz, 1H, aromat.), 8.4 (s, 1H, H-8 benzodit.), 9.84 (s, 1H,
NH) ppm. 13C-NMR (50 MHz, DMSO-d6): d 31.38 (-CH2-), 41.2
(CH2N), 58.32 (CH2OH), 119.26, 122.29 (two overlapping
signals), 126.43, 127.22, 127.53, 128.32, 128.94 (two overlapping
signals), 129.79, 130.09, 130.49, 131.75, 133.82, 134.74, 135.3,
–
–
147.10, 152.92 (C N), 162.77 (N C) ppm.
–
–
6-Chloro-1,1-dioxo-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[2-(2-pyridyl)ethylamino]-1,4,2-
benzodithiazine 14
–
–
142.15, 144.33 (18C, aromat.), 146.18, 152.49 (C N), 161.68 (N C)
ppm.
Starting from from 5 (0.53 g) and 2-(2-aminoethyl)pyridine
(0.15 g, 12 mmol); yield: 0.28 g (46%); mp 216–2178C. IR (KBr,
–
–
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Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
Synthesis, Cytotoxicity Testing, and SAR
439
1
cmꢁ1) 3185 (NH), 1670 (N C), 1625 (C N), 1325, 1160 (SO ). H-
J ¼ 6.7 Hz, 2H, CH2), 7.05–7.4 (m, 6H, Ph and H-5 pyrid.), 7.5–7.83
(m, 4H, H-4 pyrid. and aromat.), 8.06 (s, 1H, H-5 benzodit.), 8.23 (d,
J ¼ 7.9 Hz, 1H, aromat.), 8.35–8.55 (m, 3H, H-2,6 pyrid. and H-8
benzodit.), 9.93 (s, 1H, NH) ppm. 13C-NMR (DMSO-d6): d 30.99
(CH2), 44.51 (NCH2), 119.47, 122.43 (two overlapping signals),
126.39, 127.18, 127.52, 129.0 (two overlapping signals), 129.75,
130.36, 130.42, 131.59, 133.62, 134.24, 134.54, 135.35, 142.12,
145.29 (aromat.), 123.82, 124.35 (C-3 and 5 pyrid.), 136.51 (C-4
–
–
–
–
2
NMR (200 MHz, DMSO-d6): d 3.04 (t, J ¼ 7.2 Hz, 2H, CH2), 3.76 (t,
J ¼ 7 Hz, 2H, CH2), 7.22 (d, J ¼ 8.6 Hz, 2H, PhCl), 7.24–7.32 (m,
2H, H-3 and H-5 pyrid.), 7.36 (d, J ¼ 8.6 Hz, 2H, ClPh), 7.56–7.86
(m, 4H, H-4 pyrid. and 3H aromat.), 8.07 (s, 1H, H-5 benzodit.), 8.22
(d, J ¼ 7.0 Hz, 1H, aromat.), 8.4 (s, 1H, H-8 benzodit.), 8.51 (d,
J ¼ 4.7 Hz, 1H, H-6 pyrid.), 9.95 (s, 1H, NH) ppm. 13C-NMR (DMSO-
d6): d 36.03 (CH2), 43.18 (NCH2), 119.27, 124.3 (two overlapping
signals), 126.43, 127.23, 127.55, 128.32, 128.94 (two overlapping
signals), 129.81, 130.13, 130.5, 131.67, 133.76, 134.75, 135.32,
142.16, 144.33 (aromat.), 122.06, 123.57, (C-3 and 5 pyrid.), 136.88
–
pyrid.), 148.01, 150.14 (C-2 and 6 pyrid.), 145.34, 152.66 (C N),
–
–
161.98 (N C) ppm.
–
–
(C-4 pyrid), 146.2, 149.42 (C-2 and 6 pyrid.), 152.5, 158.2 (C N),
–
–
6-Chloro-7-{4-[(4-methylphenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[2-(3-pyridyl)ethylamino]-1,1-
dioxo-1,4,2-benzodithiazine 18
161.84 (N C) ppm.
–
6-Chloro-1,1-dioxo-7-{4-[(4-methylphenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[2-(2-pyridyl)ethylamino]-1,4,2-
benzodithiazine 15
Starting from from 4 (0.51 g) and 3-(2-aminoethyl)pyridine
(0.15 g, 12 mmol); yield: 0.34 g (60%); mp 249–2518C. IR (KBr,
cmꢁ1) 3180 (NH), 1688 (N C), 1625 (C N), 1325, 1160 (SO ). H-
1
–
–
–
–
2
Starting from 4 (0.51 g) and 3-(aminoethyl)pyridine (0.13 g);
NMR (200 MHz, DMSO-d6): d 2.27 (s, 3H, CH3), 2.91 (t, J ¼ 6.1 Hz,
2H, CH2), 3.64 (t, J ¼ 6.0 Hz, 2H, CH2), 7.05–7.39 (m, 5H, 4H,
PhCH3 and H-5 pyrid.), 7.54–7.88 (m, 4H, H-4 pyrid. and aromat.),
8.06 (s, 1H, H-5 benzodit.), 8.27 (d, J ¼ 7.8 Hz, 1H, aromat), 8.34–
8.50 (m, 3H, H-2,6 pyrid. and H-8 benzodit.), 9.94 (s, 1H, NH) ppm.
13C-NMR (DMSO-d6): d 20.45 (CH3), 30.99 (CH2), 44.49 (NCH2),
119.82, 123.79 (two overlapping signals), 125.27, 126.59,
127.29, 127.45, 128.44, 129.48, 129.93, 130.56, 131.62, 133.81,
134.22, 134.97, 135.37, 140.32, 142.10 (aromat.), 122.59, 123.02
(C-3 and 5 pyrid.), 136.52 (C-4 pyrid.), 148.03, 150.16 (C-2 and 6
yield: 0.30 g (53%): mp 213–2148C. IR (KBr, cmꢁ1) 3242 (NH),
1674 (N C), 1626, 1603 (C N), 1312, 1160 (SO ). 1H-NMR
–
–
–
–
2
(500 MHz, DMSO-d6) d 2.28 (s, 3H, CH3), 3.04 (t, J ¼ 7.2 Hz, 2H,
CH2), 3.77 (t, J ¼ 7.3 Hz, 2H, NCH2), 7.10–7.32 (m, 6H, H-3 and H-5
pyrid., 4H aromat.), 7.63–7.68 (m, 2H, H-4 pyrid. and aromat.),
7.72 (t, J ¼ 7.8 Hz, 1H, aromat.), 7.84 (t, J ¼ 7.8 Hz, 1H, aromat.),
8.06 (s, 1H, H-5 benzodit.), 8.29 (d, J ¼ 7.8 Hz, 1H, aromat.), 8.39
(s, 1H, H-8 benzodit.), 8.51 (d, J ¼ 3.9 Hz, 1H, H-6 pyrid.), 9.96 (s,
1H, NH) ppm. 13C-NMR (DMSO-d6): d 20.9 (CH3), 36.46 (CH2), 43.63
(NCH2), 119.26, 124.03 (two overlapping signals), 125.71, 127.04,
127.74, 127.86, 128.89, 130.37 (two overlapping signals), 130.98,
132.14, 134.35, 135.40, 135.46, 135.78, 140.75, 142.56 (aromat.),
122.52, 123.47, (C-3 and 5 pyrid.), 137.34 (C-4 pyrid.), 147.09,
–
–
pyrid.), 146.63, 152.49 (C N), 161.91 (N C) ppm.
–
–
6-Chloro-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[(6-chloro-3-pyridylmethyl)amino]-1,1-
–
–
149.87 (C-2 and 6 pyrid.), 152.94, 158.65 (C N), 162.24 (N C) ppm.
–
–
dioxo-1,4,2-benzodithiazine 19
Starting from 5 (0.53 g) and 5-(aminomethyl)-2-chloropyridine
(0.18 g, 13 mmol); yield: 0.40g (63%); mp 277–2788C. IR (KBr,
6-Chloro-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[2-(3-pyridyl)ethylamino]-1,1-
dioxo-1,4,2-benzodithiazine 16
cmꢁ1) 3165 (NH), 1665 (N C), 1630 (C N), 1320, 1160 (SO ).
–
–
–
–
2
1H-NMR (200 MHz, DMSO-d6): d 4.64 (s, 2H, NCH2), 7.22 (d,
J ¼ 8.6 Hz, 2H, PhCl), 7.36 (d, J ¼ 8.6 Hz, 2H, PhCl), 7.46–7.67
(m, 3H, aromat. and H-5 pyrid.), 7.71–7.87 (m, 2H, H-4 pyrid. and
aromat.), 8.1 (s, 1H, H-5 benzodit.), 8.22 (d, J ¼ 7.7 Hz, 1H, aro-
mat.), 8.4 (s, 2H, H-8 benzodit. and H-2 pyrid.), 10.31 (s, 1H, NH)
ppm. 13C-NMR (DMSO-d6): d 43.76 (NCH2), 119.26, 124.27 (two
overlapping signals), 127.23, 127.63, 128.32, 128.92 (two over-
lapping signals), 129.81, 130.23, 130.59, 131.47, 132.17, 133.66,
134.74, 139.7, 142.14, 144.34 (aromat.), 124.48, 126.43 (C-3 and 5
pyrid.), 135.43 (C-4 pyrid.), 149.68 (two overlapping signals of C-2
Starting from from 5 (0.53 g) and 3-(2-aminoethyl)pyridine
(0.15 g, 12 mmol); yield: 0.48 g (78%); mp 288–2908C. IR (KBr,
cmꢁ1) 3190 (NH), 1685 (N C), 1620(C N), 1325, 1160 (SO ). 1H-
–
–
–
–
2
NMR (200 MHz, DMSO-d6): d 2.91 (t, J ¼ 6.9 Hz, 2H, CH2), 3.65 (t,
J ¼ 6.9 Hz, 2H, CH2), 7.23 (d, J ¼ 8.7 Hz, 2H, PhCl), 7.28–7.41 (m,
3H, H-5 pyrid. and ClPh), 7.56–7.72 (m, 3H, H-4 pyrid. and aro-
mat.), 7.81 (dd, J ¼ 7.5 Hz, J ¼ 1.5 Hz, 1H, aromat.), 8.08 (s, 1H,
H-5 benzodit.), 8.22 (dd, J ¼ 8.4 Hz, J ¼ 1.6 Hz, 1H, aromat.), 8.4
(s,1H, H-8 benzodit.), 8.42 (d, J ¼ 1.6 Hz, 1H, H-2 pyrid.), 8.45 (dd,
J ¼ 4.6 Hz, J ¼ 2.0 Hz, 1H, H-6 pyrid.), 9.93 (s, 1H, NH) ppm.
13C-NMR (DMSO-d6): d 31.0 (CH2), 44.52 (NCH2), 119.26, 123.86,
124.29 (two overlapping signals), 127.57, 128.32, 128.94 (two
overlapping signals), 129.80, 130.15, 130.51, 131.58, 133.69,
134.26, 134.74, 136.5, 142.15, 144.33 (aromat.), 126.43, 127.23
(C-3,5 pyrid.), 135.35 (C-4 pyrid.), 147.99, 150.12 (C-2 and 6 pyrid.),
–
–
and 6 pyrid.), 146.17, 152.46 (C N), 162.43 (N C) ppm.
–
–
6-Chloro-3-[(6-chloro-3-pyridylmethyl)amino]-1,1-
dioxo-7-[4-(phenylimino)-4H-3,1-benzoxazin-2-yl]-1,4,2-
benzodithiazine 20
Starting from 6 (0.50 g) and 5-(aminomethyl)-2-chloropyridine
–
–
146.18, 152.48 (C N), 161.95 (N C) ppm.
–
–
(0.18 g, 13 mmol); yield: 0.45 g (76%); mp 251–2538C. IR (KBr,
1
cmꢁ1) 3210 (NH), 1680 (N C), 1625 (C N), 1315, 1160 (SO ). H-
–
–
–
–
2
6-Chloro-1,1-dioxo-7-[4-(phenylimino)-4H-3,1-
benzoxazin-2-yl]-3-[2-(3-pyridyl)ethylamino]-1,4,2-
benzodithiazine 17
NMR (200 MHz, DMSO-d6): d 4.62 (s, 2H, NCH2), 7.02–7.4 (m, 5H,
Ph), 7.43–7.69 (m, 3H, aromat., H-5 pyrid.), 7.71–7.89 (m, 2H, H-4
pyrid. and aromat.), 8.07 (s, 1H, H-5 benzodit.), 8.23 (d, J ¼ 7.2 Hz,
1H, aromat.), 8.4 (s, 2H, H-8 benzodit. and H-2 pyrid.), 10.20 (br.s,
1H, NH) ppm. 13C-NMR (DMSO-d6): d 43.9 (NCH2), 119.46, 122.41
(two overlapping signals), 124.50, 126.39, 127.18, 127.55, 129.0
(two overlapping signals), 129.75, 130.33, 130.45, 131.58, 132.31,
Starting from from 6 (0.50 g) and 3-(2-aminoethyl)pyridine
(0.15 g, 12 mmol); yield: 0.32 g (56%); mp 272–2738C. IR (KBr,
1
cmꢁ1) 3190 (NH), 1685 (N C), 1620 (C N), 1325, 1160 (SO ). H-
–
–
–
–
2
NMR (200 MHz, DMSO-d6): d 2.90 (t, J ¼ 6.7 Hz, 2H, CH2), 3.64 (t,
ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

440
E. Pomarnacka et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
133.76, 139.50, 139.69, 142.10 (aromat.), 124.35, 124.47 (C-3 and 5
pyrid.), 135.38 (C-4 pyrid.), 149.67 (two overlapping signals of C-2
Crystal data for 31: C29H21ClN4O3S2 ꢃ C3H8O, monoclinic, space
˚
group P21/c, a ¼ 21.0555(8), b ¼ 10.3818(4), c ¼ 13.8548(6) A,
and 6 pyrid.), 145.28, 152.67 (C N), 162.27 (N C) ppm.
b ¼ 93.378(4)8, V ¼ 3023.3(2) A , Z ¼ 4, dx ¼ 1.391 g cmꢁ3
,
, 25 149 data were collected up
crystal with dimensions 0.6 ꢂ 0.4 ꢂ
3
˚
–
–
–
–
m(Mo Ka) ¼ 0.309 mmꢁ1
to 2max ¼ 508 for
a
6-Chloro-7-{4-[(4-methylphenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[(6-chloro-3-pyridylmethyl)amino]-1,1-
0.01 mm3 (Rint ¼ 0.0748, Rs ¼ 0.0977). Final R indices for 2718
reflections with I > 2s(I) and 372 refined parameters are:
R1 ¼ 0.0687, wR2 ¼ 0.1830 (R1 ¼ 0.1352, wR2 ¼ 0.2174 for all
5319 data). The phenylethylene fragment of the molecule is
disordered over two orientations with the occupancy factors
equal to 0.69 and 0.31. The disordered fragment was refined
isotropically with common isotropic displacement parameter
for each orientation and restraints imposed on its geometry.
Crystallographic data for compounds 11 and 31 have been
deposited with the Cambridge Crystallographic Data Centre,
with the deposition Nos CCDC 768913 & 768914.
dioxo-1,4,2-benzodithiazine 21
Starting from 4 (0.51 g) and 5-(aminomethyl)-2-chloropyridine
(0.18 g, 13 mmol); yield: 0.25 g (42%); mp 221–2238C. IR (KBr,
cmꢁ1) 3225 (NH), 1672 (N C), 1630, 1602 (C N), 1320, 1160 (SO ).
–
–
–
–
2
1H-NMR (500 MHz, DMSO-d6): d 2.28 (s, 3H, CH3), 4.64 (s, 2H,
NCH2), 7.11 (d, J ¼ 6.8 Hz, 1H, H-5 pyrid.), 7.13 (d, J ¼ 8.3 Hz,
2H, PhCH3), 7.20 (d, J ¼ 8.3 Hz, 2H, PhCH3), 7.54 (d, J ¼ 8.3 Hz,
1H, aromat.), 7.66 (d, J ¼ 6.8 Hz, 1H, H-4 pyrid.), 7.8–7.88 (m, 2H,
aromat.), 8.1 (s, 1H, H-5 benzodit.), 8.29 (dd, J ¼ 8.3 Hz,
J ¼ 1.4 Hz, 1H, aromat.), 8.39 (s, 1H, H-8 benzodit), 8.41 (d,
J ¼ 2.4 Hz, 1H, H-2 pyrid.), 10.34 (s, 1H, NH) ppm. 13C-NMR
(200 MHz, DMSO-d6): d 25.86 (CH3), 49.18 (NCH2), 129.90 (two
overlapping signals), 130.63, 132.0, 132.07, 132.71, 133.87,
135.47, 136.05, 136.90, 137.57, 139.85, 140.39, 140.46, 140.90,
145.11 (two overlapping signals), 145.72 (aromat.), 124.2, 128.41
(C-3 and 5 pyrid.), 135.33 (C-4 pyrid.), 152.05, 155.07 (C-2 and 6
In-vitro cytotoxicity studies
The microtiter plate method used for cytotoxicity testing is based
on crystal violet staining of cells and has been described in detail
elsewhere [26, 27]. All the cells were obtained from the German
Collection of Microorganisms and Cell Cultures (DSMZ)
(Braunschweig, FRG). Stock solutions of compounds were pre-
pared in DMSO and diluted 1000-fold with cell culture medium
(RPMI medium þ 10% fetal calf serum) for testing. For IC50
determinations, all substances were tested at 5 serially diluted
concentrations. The corrected T/C values (T/Ccorr) for each con-
centration were calculated with the following equation:
–
–
pyrid.), 147.49, 157.87 (C N), 167.84 (N C) ppm.
–
–
6-Chloro-7-{4-[(4-chlorophenyl)imino]-4H-3,1-
benzoxazin-2-yl}-3-[(4-pyridylmethyl)amino]-1,1-
dioxo-1,4,2-benzodithiazine 22
Starting from 5 (0.53 g) and 4-(aminomethyl)pyridine (0.18 g,
16 mmol); yield: 0.40 g (68%); mp 247–2498C. IR (KBr, cmꢁ1
)
ðT=CÞcorrð%Þ ¼ ðO:D:TꢁO:D:C;0Þ=ðO:D:CꢁO:D:C;0AÞ ꢂ 100
3200 (NH), 1675 (N C), 1625, 1601 (C N), 1320, 1160 (SO ) 1H-
–
–
–
–
2
where T is the optical density at l ¼ 570 nm (OD570) of the
treated cells at after a 96 h treatment time, C is the OD570 of
the untreated cells after 96 h of growth without substance,
C,0 is the OD570 of the cells on at the time of treatment (i.e.
96 h before T and C). Linear regression analysis of the log
concentration versus the T/Ccorr plots was used to estimate the
concentration of substance that caused a T/Ccorr ¼ 50%
(IC50). At least three independent experiments were done
to determine the IC50 values.
NMR (200 MHz, DMSO-d6): d 4.64 (s, 2H, NCH2), 7.22 (d, J ¼ 8.7 Hz,
2H, PhCl), 7.28–7.46 (m, 4H, PhCl and H-3,5 pyrid.), 7.56–7.68 (m,
2H, aromat.), 7.81 (dd, J ¼ 6.6 Hz, J ¼ 7.6 Hz, 1H, aromat.), 8.12
(s, 1H, H-5 benzodit.), 8.23 (d, J ¼ 7.4 Hz, 1H, aromat.), 8.39 (s, 1H,
H-8 benzodit.), 8.57 (br.s, 2H, H-6 and H-2 pyrid.), 10.2 (br.s, 1H,
NH) ppm. 13C-NMR (200 MHz, DMSO-d6): d 51.10 (NCH2), 129.69
(two overlapping signals), 129.90, 131.85, 132.65, 133.05, 133.76,
134.36 (two overlapping signals) 134.86, 135.24, 135.86, 136.04,
136.90, 139.07, 140.18, 140.86, 147.57 (aromat.), 124.68, 128.42
(C-3 and 5 pyrid.), 135.67 (C-4 pyrid.), 151.59, 155.33 (C-2 and 6
–
–
–
pyrid.), 149.75, 157.89 (C N), 168.19 (N C) ppm.
–
Descriptor calculations
Molecular models of the amines R2 were constructed and mini-
mized with the software PCModel (Serena Software, Bloomington,
IN, USA, ver 8.50). The MMX force field of PCModel was used in the
calculation of the following descriptors: the saturated surface area
(SSA), the unsaturated surface area (USA), the polar surface area
(PSA), the molecular volume (molvol) and the molar volume (Mvol)
of each fragment. The structures were imported into the program
CAChe (Fujitsu Biosystems Group, Beaverton, OR, USA, ver
7.5.0.85) and the following descriptors were calculated with the
PM5 semi-empirical method at the PM5 minimum: Dipole
moment (DM), HOMO and LUMO energies, molecular refractivity
(MR), polarizability (P), heat of formation (HF), water assessable
surface area (WASA) and ionization potential (IP). Further descrip-
tors calculated by CAChe were: Molecular weight (MW), logP, and
the kappa shape indexes, orders 1, 2 and 3 (KSI-1, KSI-2, KSI-3).
X-ray crystal structure analysis
The diffraction data for single crystals of compounds 11 and the
previous described 31 [15] were collected at 130 K with a
KumaCCD diffractometer using graphite monochromated Mo
Ka radiation. The intensity data were collected and processed
using Oxford Diffraction CrysAlis Software [30]. The structures
were solved by direct methods with the program SHELXS-97 [22]
and refined by full-matrix least-squares method on F2 with
SHELXL-97 [31].
Crystal data for 11: C24H16Cl2N4O3S2 ꢃ C2H6OS, triclinic, space
˚
group P-1, a ¼ 6.7802(4), b ¼ 10.3058(7), c ¼ 19.8403(9) A,
a ¼ 98.845(5), b ¼ 97.206(4), g ¼ 100.563(6)8, V ¼ 1329.70(13)
3
A , Z ¼ 2, dx ¼ 1.552 g cmꢁ3, m(Mo Ka) ¼ 0.522 mmꢁ1, 19 305
˚
data were collected up to 2max ¼ 52.748 for a crystal with dimen-
sions 0.6 ꢂ 0.04 ꢂ 0.02 mm3 (Rint ¼ 0.0380, Rs ¼ 0.0753). Final
R indices for 3374 reflections with I > 2s(I) and 360 refined
parameters are: R1 ¼ 0.0309, wR2 ¼ 0.0629 (R1 ¼ 0.0649,
wR2 ¼ 0.0723 for all 5402 data). The allyl group shows a minor
disorder.
Correlation analysis
Initial multiple regression analysis was performed with the
CAChe ProjectLeader software. The dependent variable used in
ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2011, 344, 431–441
Synthesis, Cytotoxicity Testing, and SAR
441
the calculations was the negative log(IC50). The independent
variables included the descriptors described above as well as
two indicator variables, ICl and ICH3, which were set to 1
when R1 was a chlorine or methyl group, respectively, or set
to 0 when R1 was hydrogen. The program was used to identify the
QSAR equations with the data best fitted to one, two and three
variables from all possibilities. Multiple regression analysis of
the best-fitted equations with two and three variables was
repeated with MS-Excel (ANOVA analysis). Leave-one-out cross-
validation was performed with the cross-validated squared cor-
relation coefficient rCV2, correlation with the Pearson corre-
lation coefficient r, and significance was determined by the F-test.
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[14] S. E. Rokita, K. D. Karlin, K. J. Humphreys, L. Li, N. N. Murthy,
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[15] E. Pomarnacka, M. Maruszak, K. Langowska, P. Reszka, P. J.
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´
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We wish to thank the EU for Erasmus scholarships to AK.
The authors have declared no conflict of interest.
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www.archpharm.com