A New Method for the Preparation of Intermediates for 2,6-Substituted Anthrapyridazones

Article abstract of DOI:10.1002/jhet.2738

A new method for the preparation of 2-substituted 6-chloro-2,7-dihydro-3H-dibenzo[de,h]cynnoline-3,7-diones has been developed. The compounds have been obtained in an original three-step procedure comprising the oxidation of 1-methyl-9,10-anthraquinones with periodate or permanganate/brominating reagent systems, cyclization to 6-chloro-2,7-dihydro-3H-dibenzo[de,h]cynnoline-3,7-dione, and selective alkylation thereof. The selected processes were applied in the efficient scale-up of specific 2,6-substituted 2,7-dihydro-3H-dibenz[de,h]cinnolin-3,7-dione derivatives, currently being investigated pre-clinically as anticancer agents.

Full text of DOI:10.1002/jhet.2738

Month 2016
A New Method for the Preparation of Intermediates for 2,6-Substituted
Anthrapyridazones
*
Marcin Cybulski, Katarzyna Sidoryk, Adam Formela, Olga Michalak, Anna Rosa, Katarzyna Mróz, and
Wioleta Maruszak
Pharmaceutical Research Institute, 8 Rydygiera Street, 01-793 Warsaw, Poland
*
E-mail: m.cybulski@ifarm.eu
Additional Supporting Information may be found in the online version of this article.
Received March 14, 2016
DOI 10.1002/jhet.2738
Published online 00 Month 2016 in Wiley Online Library (wileyonlinelibrary.com).
A new method for the preparation of 2-substituted 6-chloro-2,7-dihydro-3H-dibenzo[de,h]cynnoline-
3,7-diones has been developed. The compounds have been obtained in an original three-step procedure
comprising the oxidation of 1-methyl-9,10-anthraquinones with periodate or permanganate/brominating
reagent systems, cyclization to 6-chloro-2,7-dihydro-3H-dibenzo[de,h]cynnoline-3,7-dione, and selective
alkylation thereof. The selected processes were applied in the efficient scale-up of specific 2,6-substituted
2,7-dihydro-3H-dibenz[de,h]cinnolin-3,7-dione derivatives, currently being investigated pre-clinically as
anticancer agents.
J. Heterocyclic Chem., 00, 00 (2016).
INTRODUCTION
moiety, that is, anthrapyridazone derivatives. It has been
described that an improved solubility and the increase in
the cytotoxic activity may be obtained by introducing
[(alkylamino)alkyl]amino side chains into the positions 2
and 6 of the anthrapyridazone ring. Recently, another
group of asymmetrically 2,6-disubstituted 2,7-dihydro-
3H-dibenz[de,h]cinnoline-3,7-diones has been disclosed.
These analogs exhibit a high cytostatic activity against
MDR tumor cells with the overexpression of different
exporting pumps, MDR-1, BCRP, and MRP, and against
a broad spectrum of resistant cell lines derived from
different tissues and patient organs. Although the new
MDR compound class was successfully synthetized in a
small laboratory scale, we observed several problems
during the preparation of their two intermediates in a
multigram scale: anthraquinone acid (2) and 2-substituted
anthrapyridazones (6, Scheme 1) [18,19].
The established methods for the preparation of
4-substituted 9,10-anthraquinone-1-carboxylic acids (2)
are based on the oxidation of the methyl group in a partic-
ular anthraquinone derivative (1). Both scientific and
patent literature sources describe several methods of the
methyl group oxidation in 1-methyl-9,10-anthraquinones.
The most common one is the oxidation with the diluted
nitric acid under high pressure in a sealed tube at the
temperature of 195–220°C [20,21]. As an alternative,
patent literature discloses a method for the oxidation of
the starting 1-chloro-4-methyl-9,10-antrhtaquinone (1a):
in the solution of the acetic acid in the presence of air
and daylight [22]; in nitrobenzene, by passing chlorine
gas through the reaction mixture at the temperature of
Natural and synthetic 9,10-anthraquinone derivatives are
widely used in the chemical industry and in medicine. The
9,10-anthraquinone moiety occurs as a natural pigment in
plants, fungi, lichens, and insects [1–5]. One of the
anthraquinone classes contains compounds with a carbonyl
substituent, such as those isolated from plants: rhein,
diacerein, and emodic acid [6]. These natural or synthetic
anthraquinones find their application as building blocks
in the synthesis of the compounds with a biological activity
(Fig. 1) [7–10]. Anthraquinones are known for their
laxative [11], antifungal [12], antimalaric [13], and
anticancer properties (Fig. 2) [14]. Mitoxantrone, a
9,10-anthraquinone derivative, has long been registered
as an anticancer therapeutic [15–17]. However, like other
clinical anticancer drugs, it undergoes the phenomenon of
phenotypic, multidrug cross-resistance of tumor cells
(multidrug resistance (MDR)), related to the removal of
drugs from cells via specific transport proteins. The
observed overexpression of transporter proteins in tumors
diminishes the therapeutic effect of drugs and therefore
the effectiveness of therapy. Thus, the occurrence of the
multidrug resistance effect has necessitated studies on
new active compounds against the resistant cells, including
anthraquinone derivatives. To date, a group of compounds
with an additional heterocyclic ring connected to the
anthraquinone core has revealed some activity toward
resistant cancer cells. Among them, the most interesting
profile is displayed by tetracyclic compounds with an
additional pyridazone ring fused to the anthraquinone
© 2016 Wiley Periodicals, Inc.

M. Cybulski, K. Sidoryk, A. Formela, O. Michalak, A. Rosa, K. Mróz, and W. Maruszak
Vol 000
Figure 1. Chemical structures of some derivatives with the anthraquinone core exhibiting an anticancer and/or antifungal activity.
Figure 2. Chemical structures of some anthraquinones isolated from plants (rhein, diacerein, emodic acid, and sennoside A) [6] and insect pigments
(laccaic acid D and kermesic acid) [4].
Scheme 1. Synthetic routes for obtaining 8 (reference route A: (a) 16% HNO3 aq/200°C, (d) PCl5/benzene; present route B: (a) NaIO4/LiBr/80°C, (b)
SO2Cl2/toluene/80% hydrazine monohydrate, and (c) K2CO3/CHCl3/CH3OH).
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2016
A New Method for the Preparation of Intermediates for 2,6-Substituted
Anthrapyridazones
160–170°C [23]. Another known methods involve oxida-
tions with the fuming sulfuric acid or oleum [24,25]. All
the aforementioned procedures require aggressive reagents
and harsh reaction conditions including high pressure and
temperature.
Another major problem in the synthesis of
anthrapyridazones 8 is obtaining their monosubstituted
intermediates 6. According to the known literature
While searching for a milder, easier to handle, and more
economical oxidation of 1-methyl-9,10-anthraquinones,
numerous methods for the oxidation of the methyl group
in aromatic compounds were found [27–30]. We examined
literature procedures with the commonly used oxidants,
that is, potassium permanganate, sodium dichromate,
CrO3, and HNO3 in the atmospheric pressure with no
positive result. It had been reported before that the direct
oxidation of alkylarenes mediated by the sodium
periodate/lithium bromide combination produces benzyl
acetates through benzyl bromides in the acetic acid or
benzoic acids in the diluted inorganic acid [31,32]. Based
on these results, we examined a variety of reaction condi-
tions with or without the bromine source (Table 1) and
the sodium periodate or potassium permanganate in
order to find an effective oxidizing system for 1-chloro-
4-methyl-9,10-anthraquinone (1a) and 1,4-dimethyl-
9,10-anthraquinone (1b). Contrary to literature data, the
oxidation was observed not only in the presence of the lith-
ium bromide. A comparable efficiency was achieved when
using potassium or sodium bromides as the halogen source.
A low transformation level to 4-chloroanthraquinone-
1-carboxylic acid (2a), that is, 3–7%, took place in the
absence of the bromine source or while using sodium chlo-
ride or cuprous bromide as the accompanying salts. The
consumption of the starting 1-methyl-9,10-anthraquinone
derivatives in the presence of the oxidation reagents was
examined by HPLC. The HPLC samples were obtained
after the final workup of the reaction mixtures. An almost
insoluble acid was isolated by a simple filtration. The
filtrate was extracted with chloroform and ethyl acetate in
order to recover the starting material after evaporating
the solvent excess. The organic residues were combined
and homogenized before the HPLC analysis. Attempts
to use other solvent systems (chloroform/diluted sulfuric
acid, tetrahedrofuran/diluted sulfuric acid, methylene
chloride/process water) in order to increase the yield and
shorten the reaction time all failed. The extended reaction
time proved to be an essential factor for the effectiveness
of the oxidation (Table 1). The purity of 4-
chloroanthraquinone-1-carboxylic acid (2a) exceeding
83% was reached in 144h, while the quenching after 48h
resulted in only 16% of the transformation. An increase
in the reaction temperature to 110°C neither shortened
the reaction time nor improved the yield significantly.
The electrophilic ring bromination was neither observed.
Interestingly, the oxidation product was determined in the
bromine-treated reaction mixture with the yield of 22.4%
(Table 1). One of the highest transformations was observed
while using the potassium permanganate/bromine system;
however, that condition was very difficult to apply in a
larger scale because of the problematic separation of hardly
soluble 4-chloroanthraquinone-1-carboxylic from the in-
soluble manganese dioxide inorganic impurity.
methodology
[18,19],
2,7-dihydro-3H-dibenz[de,h]
cinnoline-3,7-diones with the (alkylamino)alkyl substitu-
ent in position 2 of the tetracyclic ring can be obtained
through the condensation of 4-chloroanthraquinone-1-
carboxylic acid (2), previously converted to the respective
chloride, and (alkylamino)alkyl hydrazine derivative
(5) (Scheme 1, reaction d). Thereby, a group of
2-substituted 2,7-dihydro-3H-dibenz[de,h]cinnoline-3,7-
diones with (dimethylamino)ethyl, (dietylamino)ethyl,
(morfoline)ethyl, and (piperidineamino)ethyl spacers was
isolated in the yield of only 20–60% after the purification
by column chromatography. The aforementioned strategy
seems to be problematic in the upscaling process because
of the necessity to obtain harmful (alkylamino)alkyl hydra-
zine precursors (5). The synthesis of 5 includes several
hours of heating of the corresponding (alkylamino)alkyl
chloride (4a–e) with 60–80% hydrazine solution in water
[26]. The resulting product is difficult to characterize, a
high boiling mixture of different compounds, such as di-
substituted (alkylamino)alkyl hydrazines. The purification
requires distillation under reduced pressure of 15–20mbar
and eventually a reliable analytical method to characterize
the expected product. It results in low yields of the hydra-
zine derivatives 5a–e (20–30%).
Taking into consideration the aforementioned limita-
tions, we have decided to search for new, effective, and re-
producible synthetic methods that by allowing us to
prepare intermediates 2 and 6 would lead us to obtain
2,7-dihydro-3H-dibenz[de,h]cinnolin-3,7-dione
tives (8) for preclinical tests.
deriva-
Herein, we describe new improvement methods for the
synthesis of 2 and 6 intermediates: building blocks for
compounds with a cytostatic activity against multidrug
resistance cell lines.
RESULTS AND DISCUSSION
During our studies on the 2,7-dihydro-3H-dibenz[de,h]
cinnolin-3,7-diones (8) synthesis, it was experimentally
verified that only the method using the diluted nitric acid
guarantees an adequate purity of anthraquinone-1-
carboxylic acids. However, it seemed to be problematic
in the upscaling process, because it forced us to use an au-
toclave resistant to the corrosive nitric acid and nitrogen
oxides.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Cybulski, K. Sidoryk, A. Formela, O. Michalak, A. Rosa, K. Mróz, and W. Maruszak
Vol 000
Table 1
Oxidative brominationa of 1a with NaIO4 or KMnO4 and a bromine source.
HPLC purityc
Entry
Bromine source
Oxidant
Solvent
Reaction time (h)
Temp (°C)
1
2
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1b
1c [33]
1c [33]
1d [20]
1d [20]
1e [34]
1e [34]
—
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
KMnO4
KMnO4
—
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
NaIO4
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/H2O
96
48
96
144
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
85
85
85
85
85
60
85
85
85
85
85
85
85
85
85
85
85
85
85
85
90.55
80.54
41.36
14.14
76.44
91.13
30.55
34.93
88.33
91.74
81.83
23.26
75.74
38.50
5.48
15.60
56.67
83.80
21.01
5.09
68.06
63.02
7.24
3.35
12.18
75.03
22.40
61.19
—
LiBr
LiBr
LiBr
LiBr
LiBr
KBr
Chloroform/H2O
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
Chlorobenzene/0.5 M H2SO4 1:1
NaBr
CuBr
NaCl
LiBr
b
Br2b
Br2
LiBr
LiBr
KBr
LiBr
KBr
LiBr
KBr
d
—
d
—
—
—
—
—
d
—
d
—
d
—
d
—
—
aConditions: substrate (3.9 mmol), oxidant (11.7 mmol), metal bromide (11.7 mmol), solvent (20 mL), tetrabutylammonium bromide (10 mol%).
bFor bromine (5.9 mmol).
cDetermination of the HPLC purity for the substrate and product combined after the reaction workup.
dLack of product 2 on the TLC plates.
In addition, effective reaction conditions for obtaining 4-
substituted 9,10-anthraquinone-1-carboxylic acids (2a–b)
were examined for their ability to oxidize 2- and 3-
methyl-9,10-anthraquinone derivatives [20,33,34] (1c–e)
to respective acids (2c–e). Unfortunately, when the sodium
periodate/bromide salt systems were used (Table 1), the
formation of the expected products was not observed on
the TLC plates.
In order to develop an efficient method for the synthe-
sis of intermediates 6, we first verified the literature data.
As it was reported, any attempts to repeat the known
procedure of direct formation of the tetracyclic ring from
acid 2 [18,19] and (alkylamino)alkyl hydrazine substrates
(5) [26] showed that the main problems included: low
yields of the non-commercial substrates 5 synthesis, their
purification by distillation under reduced pressure, and
difficult analytical evaluation. In addition, following the
distillation process the decomposition of compounds 5a
1
and b was observed on the H NMR spectrum. Because
of these technological complications, we preferred to find
original conditions for obtaining
procedure, that is, the reaction of 2 with hydrazine, then
the alkylation of with commercially certified
6 in a two-step
3
2-(dimethylamino)ethyl chloride hydrochloride (4a).
Compound 3 was obtained with 4-chloroanthraquinone-
1-carboxylic acid 2 and 80% hydrazine hydrate in the
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2016
A New Method for the Preparation of Intermediates for 2,6-Substituted
Anthrapyridazones
presence of thionyl chloride with a good 74% yield. In
the second step, the alkylation of 3 required us to try a
variety of electrophilic reagents as well as different
solvents and temperature conditions in order to find the
most efficient method. First of all, literature procedures
for the alkylation of pyridazinones [35–41] were tested.
However, the attempts to directly transfer the published
impurities were detected, except for the substrate and
the product. While the reactions were carried out in alco-
hols MeOH and EtOH (Table 2; entries 16, 17), only
traces of the product were observed. During our system-
atic modifications of reaction conditions, followed by
the examination of the substrate conversion and the purity
of the alkylation processes, it was revealed that chloro-
form may be the most promising medium for this type
of reaction (Table 2; entry 18). The reaction carried out
in the presence of 6 equiv of potassium carbonate at 40°C
for 24h provided 80% of 6a in a crude reaction mixture.
Extending the reaction time to 48h caused a partial
decomposition of product 6a. As a consequence, a
decrease in purity to 70% (Table 2; entry 19) was
observed. Further investigation showed that the alkylation
procedure can be improved by using a mixture of chloro-
form with some amount of polar MeOH as a solvent. The
best result was observed at 20% of MeOH in relation to
the chloroform volume in the presence of 6equiv of po-
tassium carbonate and 5 equiv of 2-(dimethylamino)ethyl
chloride hydrochloride (Table 2; entry 20). This optimized
procedure was verified through the alkylation of 3 with
alkylaminoalkyl chlorides (4b, 4c, 4d, and 4e). In all
experiments, an appropriate product (6b, 6c, 6d, and 6e)
was obtained with a good yield ranging from 80 to
100% (see Experimental section). The structures of all
compounds were confirmed by extended 1H and 13C
NMR experiments as well as HR-MS (Experimental
section). The purity of all products was verified by the
reaction conditions to the alkylation of
3
by
2-(dimethylamino)ethyl chloride hydrochloride (4a)
failed. Initial experiments were performed in DMF or
toluene in the presence of NaH, KOH, or NaOH
(Table 2; entries 1, 2, and 3) because of the fair solubility
of substrate 3 in that solvent/base systems. Unfortunately,
we detected fast decomposition of starting material 3 for
those strong bases. After changing the base for potassium
carbonate, different results for toluene and DMF were
observed. A reaction in nonpolar toluene and at ambient
temperature did not lead to the alkylation of substrate 3.
However, an increase in the reaction temperature resulted
in the decomposition of the starting material. A better
effect was observed for the reaction carried out in DMF
at ambient temperature (Table 2; entry 5), although 6a
was detected with a 55.8% purity. Taking into consider-
ation the results collected from the DMF reactions, a
conversion in other polar solvents, that is, acetone, aceto-
nitrile, DMSO, or NMP, was evaluated. Unfortunately, a
decrease in the 6a formation was observed during these
attempts. The purity varied from about 8% to 33% in
crude reaction mixtures, and numerous unknown
Table 2
Optimization of 3 alkylation condition in a model compound 6a.
HPLC
Entry
Base
Solvent
Reaction time (h)
Temp. (°C)
3
6a
1.
2.
3.
4.
5.
6.
7.
8.
NaH (60%, 1.5 eq.)
KOH, TBAB
DMF
toluene
toluene
DMF
DMF
DMF
acetone
acetonitrile
DMF
24
5
5
rt
rt
50
rt
rt
40
rt
rt
rt
rt
rt
Decomp.
66.6
Decomp.
50.3
13.5
3.7
32.8
26.7
4.2
9.5
10.3
1.0
54.4
11.6
—
—
5.8
—
5.6
55.8
40.4
35.5
28.7
31.3
12.4
30.7
33.7
8.1
NaOH, TBAB
K2CO3 (1.5 eq.)
K2CO3 (3 eq.)
K2CO3 (2 eq.)
K2CO3 (2 eq.)
K2CO3 (2.3 eq.)
K2CO3/KJ (2 eq.)
K2CO3/H2O (2 eq.)
K2CO3 (2 eq.)
K2CO3 (2 eq.)
K2CO3 (2 eq.)
K2CO3 (4 eq.)
K2CO3 (6 eq.)
K2CO3 (6 eq.)
K2CO3 (6 eq.)
K2CO3 (6 eq.)
K2CO3 (6 eq.)
24
24
24
48
48
48
48
4
9.
10.
11.
12.
13.
15.
16.
17.
18.
19.
20.
DMF
DMSO
DMSO
NMP
DMF
MeOH
EtOH
24
6
rt
rt
24
24
24
24
48
24
50
40
40
40
40
40
47.9
a
—
a
—
—
CHCl3
CHCl3
CHCl3/MeOH
1.17
0.08
—
80.0
70.15
90.0
aMonitoring by the TLC method.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Cybulski, K. Sidoryk, A. Formela, O. Michalak, A. Rosa, K. Mróz, and W. Maruszak
Vol 000
C-18 RPHPLC method using acetonitrile–water as the
mobile phase.
solvent A (0.1% trifluoroacetic acid in water) and solvent
B (0.1% trifluoroacetic acid in acetonitrile). The flow rate
of 1.0 mL/min was used. The UV detection was carried
out at 248nm. The samples were prepared at the concentra-
tion of about 0.20mg/mL and were dissolved in
acetonitrile–methanol (4:1). The injection volume was
10 μL. The column was placed in a thermostated column
heater at 30°C.
In conclusion, our results show that the new current pro-
cedure for the preparation of 2-substituted 6-chloro-2,7-
dihydro-3H-dibenzo[de,h]cynnoline-3,7-diones (6) offers
an attractive alternative to the reported methods for the
preparation thereof. These compounds are used as interme-
diates in the synthesis of potential anticancer agents 8 [19].
The three-step process comprises efficient methods of 1-
methyl-9,10-anthraquinones (1a–b) oxidation to the 4-
substituted 9,10-anthraquinone-1-carboxylic acids (2a–b)
and selective alkylation of 3 with commercially available
(alkylamino)alkyl chlorides hydrochloride (4a–e).
4-Chloro-9,10-dihydro-9,10-dioxo-1-anthracenecarboxylic
acid (2a)
Preparation with the NaIO4/LiBr system. The diluted sul-
furic acid (10 mL, 2.5% (v/v)), sodium metaperiodate
(2.5 g, 11.7 mmol), lithium bromide (1.02g; 11.7mmol),
and tetrabutylammonium bromide (0.1 g, 0.3 mmol) were
added to the solution of 1-chloro-4-methylanthraquinone
[22] (1.00g, 3.9 mmol ) in chlorobenzene (10 mL). The re-
action was stirred and heated for 144h at 80–85°C. After
cooling to the ambient temperature, the crude product
was filtered, washed with saturated sodium thiosulfate so-
lution, then with deionized water. The yellow crystals were
air dried and purified by crystallization from
methanol/water. Yield 0.82 g (73%). HPLC purity
99.96%. 126.26. M.p. = 231.5 (228–229°C) [20].
Compound
3
may be easily obtained from 4-
chloroanthraquinone-1-carboxylic acid 2a in a sequence
of reactions with thionyl chloride and 80% hydrazine hy-
drate. However, the application of the proposed oxidation
method to the strategy of the 2,7-dihydro-3H-dibenz[de,
h]cinnolin-3,7-dione derivatives (8) synthesis prolongs
the reaction time, and the ease of manipulation (lower tem-
perature, easier-to-handle oxidation reagents, atmospheric
pressure, andstandard laboratory equipment) seems to be
advantageous in a bigger scale. Although we did not fully
optimize the conditions of the processes, the proposed
experimental procedure allowed us to reproducibly obtain
hundreds of grams of 2a with pharmaceutical purity.
Therefore, it is our belief that further optimization might
shorten the reaction time and be attractive to chemists.
1H NMR (DMSO-d6; 600 MHz) δ 13.25 (m, 1H,
COOH), 8.16 (dd, J = 7.5 Hz, J= 1.5 Hz, 1H, Ar–H), 8.11
(dd, J= 7.5 Hz, J = 1.5 Hz, 1H, Ar–H), 7,99 (d, J =8.2 Hz,
1H Ar–H), 7.94 (ddd, J =7.5 Hz, J = 1.5 Hz, 1H, Ar–H),
7.91 (ddd, J = 7.5 Hz, J =1.5 Hz, 1H, Ar–H), 7.78 (dd,
J = 8.2 Hz, 1H, Ar–H); 13C NMR (DMSO-d6; 600 MHz) δ
181.39, 180.90, 169.53, 137.39, 135.46, 134.84, 134.27,
133.94, 133.85, 132.48, 132.29, 131.99, 129.67, 126.87.
Preparation with the Br2/KMnO4 system. The diluted sul-
furic acid (10 mL, 2.5% (v/v)), potassium permanganate
(0.92 g; 5.8 mmol), and bromine (0.93g; 5.8mmol) were
added to the solution of 1-chloro-4-methylanthraquinone
(1.00 g, 3.9 mmol) in chlorobenzene (10mL). The reaction
was stirred and heated for 96 h at 80–85°C. After cooling to
the ambient temperature, the crude product was filtered and
washed with deionized water. The precipitate was suspended
in acetone (200mL) and stirred for 30 min in the ambient tem-
perature. The inorganic salt was filtered off, and the filtrate
was evaporated in vacuo to give a crude product. After crys-
tallization from methanol/water, 0.84 g of 4-chloro-9,10-
dihydro-9,10-dioxo-1-anthracenecarboxylic was obtained
with the yield 75%. HPLC purity 99.91%.
EXPERIMENTAL
All reagents and solvents were purchased from common
commercial suppliers and were used without further purifi-
cation. The NMR spectra were recorded on a Varian
VNMRS 600, Varian VNMRS 500, and Varian Gemini
200 spectrometers (at 298K) in CDCl3 and DMSO-d6,
using TMS (δ= 0.0 ppm) as an internal standard. Standard
experimental conditions and standard Varian programs
were used. The melting points were measured on a Büchi
melting point apparatus and were uncorrected. The chro-
matographic analysis was performed using Dionex Ulti-
Mate 3000 UHPLC systems. The chromatographic
separation for 2a–b was achieved on a Kinetex C18,
150×4.6-mm, 2.6-μm column using a gradient mixture of
solvent A (0.1% orthophosphoric acid in water) and sol-
vent B (acetonitrile). The flow rate of 1.0 mL/min was
used. The UV detection was carried out at 254nm. The
samples were prepared at the concentration of about
0.25mg/mL and were dissolved in methanol. The injection
volume was 10 μL. The column was placed in a
thermostated column heater at 30°C. The chromatographic
separation for 3, 6a–b was achieved on a XBridge C18,
150×4.6-mm, 3.5-μm column using a gradient mixture of
4-Methyl-9,10-dihydro-9,10-dioxo-1-anthracenecarboxylic
acid (2b).
Sulfuric acid (10 mL, 2.5% (v/v)), sodium
metaperiodate (2.72 g, 12.7 mmol), lithium bromide
(1.10 g; 12.7 mmol), and tetrabutylammonium bromide
(0.1 g, 0.3 mmol) were added to the solution of 1,4-
dimethylanthraquinone [28] (1.00 g, 4.2 mmol) in
chlorobenzene (10 mL). The reaction was stirred and
heated for 144 h at 80–85°C. After cooling to the
ambient temperature, the crude product was filtered,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2016
A New Method for the Preparation of Intermediates for 2,6-Substituted
Anthrapyridazones
washed with the saturated sodium thiosulfate solution,
then with deionized water. The yellow crystals were air
dried (96.07% of the HPLC purity) and purified by
crystallization from methanol/water. Yield 0.69 g (61%).
HPLC purity 99.25%. M.p. = 231–232 (230–231°C) [42].
1H NMR (DMSO-d6; 600MHz) δ 13.52 (m, 1H,
COOH), 8.13 (dd, J =7.5 Hz, J = 1.5 Hz, 1H, Ar–H), 8.09
(dd, J =7.5Hz, J =1.5 Hz, 1H, Ar–H), 7.90 (ddd,
J =7.5 Hz, J = 1.5 Hz, 1H, Ar–H), 7.88 (ddd, J= 7.5 Hz,
J =1.5 Hz, 1H, Ar–H), 7.74 (d, J= 8,0 Hz, 1H Ar–H),
7.66 (dd, J = 8.0 Hz, 1H, Ar–H), 2.77 (s, 3H, CH3); 13C
NMR (DMSO-d6; 600MHz) δ 184.07, 182.47, 170.40,
142.05, 137.89, 134.98, 134.64, 134.12, 133.89, 132.21,
131.43, 131.17, 131.00, 126.78, 126.19, 22.96.
2-[2-(Dimethyloamino)propyl]-6-chloro-2,7-dihydro-3H-dibenzo
[de,h]cynnoline-3,7-dione (6b). To the suspension of 3 (0.5g,
1.77mM) in chloroform (30 mL), K2CO3 (1.5g, 10.85mM)
and 3-dimethylamino-1-propylchloride hydrochloride (1.27g,
8.85mM) were added, then the mixture was stirred at 40°C for
48h (HPLC monitoring). The inorganic solid was filtered and
washed with chloroform (40 mL). The organic residue was
evaporated to dryness, and product 6b was obtained as an
orange solid (0.423 g, HPLC purity 88.02%, 68% yield). HR-
MS (ESI) Calcd for C20H18ClN3O2 [M +H]+: 368.1166.
Found: 368.1159; 1H NMR (CDCl3, 200MHz) δ 8.63 (d, 1H,
J= 8.7 Hz), 8.49 (dd, 1H, J=1.1Hz, J= 8.0Hz), 8.40 (dd, 1H,
J=1.1Hz, J=7.7 Hz), 7.97 (d, 1H, J= 8.7 Hz), 7.75 (ddd, 1H,
J=1.4Hz, J= 7.3 Hz), 7.65 (ddd, 1H, J=1.4Hz, J=7.3Hz),
4.44 (t, 2H, J=7.3Hz, J=14.4Hz), 2.52 (t, 2H, J=6.9Hz,
J= 14.6 Hz), 2.27 (s, 6H), 2.22–2.10 (m, 2H); 13C NMR
(CDCl3, 200MHz) δ 180.66, 158.26, 142.22, 135.82, 134.35,
133.75, 132.44, 132.40, 131.36, 130.17, 128.27, 127.79,
125.53, 123.13, 56.74, 50.18, 45.40, 26.73.
6-Chloro-2,7-dihydro-3H-dibenzo[de,h]cynnoline-3,7-dione
(3).
To the suspension of 4-chloroanthraquinone-1-
carboxylic acid (5) (6 g, 21mM) in 150mL of toluene,
SOCl2 (3.06 mL, 42mM) was added, and the mixture was
stirred at reflux for 1 h. Next, the solution was cooled to
40–50°C, and the hydrazine hydrate (3.06 mL, 63mM,
80%) was added. The reaction mixture was stirred at
reflux for 1.5h. Then AcOEt (75 mL) was added to the
cooled mixture, and the suspension was stirred for 30min.
The precipitate was filtered and washed with AcOEt,
water, and MeOH. The crude product was refluxed with
MeOH (70 mL) for 30min, next the product was filtered,
washed with MeOH, and dried (4.39 g, HPLC purity
94.61%, 74% yield). HR-MS (ESI) Calcd for C15H7N2O2
[M+ Na]+: 305.0079. Found: 305.0094; 1H NMR
(DMSO-d6, 200MHz) δ 13.52 (s, 1H), 8.51 (d, 1H,
J =8.4Hz), 8.40 (d, 1H, J =7.7 Hz), 8.28 (m, 1H), 8.10 (d,
1H, J = 8.5Hz), 7.90–7.81 (m, 1H), 7.80–7.65 (m, 1H);
13C NMR (CDCl3, 200MHz) δ 180.17, 158.74, 140.44,
135.73, 134.27, 134.07, 132.54, 132.11, 130.76, 130.14,
128.63, 127.11, 125.76, 124.08, 122.70.
2-(2-Morfolinethyl)-6-chloro-2,7-dihydro-3H-dibenzo[de,
h]cynnoline-3,7-dione (6c). To the suspension of 3 (0.1g,
0.35mM) in chloroform (10mL) and MeOH (1mL),
K2CO3 (0.29g, 2.12mM) and 4-(2-chloroethyl)morpholine
hydrochloride (0.33 g, 1.77 mM) were added, then the
mixture was stirred at 50°C for 48h (HPLC monitoring).
The inorganic solid was filtered and washed with
chloroform (20mL). The organic residue was evaporated to
dryness. The product was purified by column
chromatography (eluent: chloroform) to afford compound
6c as an orange solid (0.15g, HPLC purity 89.2%, 100%
yield). HR-MS (ESI) Calcd for C21H18ClN3O3 [M+H]+:
1
396.1115. Found: 396.1102; H NMR (CDCl3, 500MHz)
δ 8.56 (d, 1H, J=8.54Hz), 8.39 (d, 1H, J=7.95Hz), 8.33
(dd, 1H, J=0.6Hz, J=7.95Hz), 7.92 (d, 1H, J=8.55Hz),
7.75–7.71 (m, 1H), 7.64–7.60 (m, 1H), 4.53 (t, 2H,
J=6.5Hz, J=13.3Hz), 3.68–3.67 (m, 4H), 2.96 (t, 2H,
J=6.5Hz, J=13.3Hz), 2.63 (brs, 4H); 13C NMR (CDCl3,
500MHz) δ 180.56, 158.31, 142.27, 135.86, 134.38,
133.74, 132.44, 132.41, 131.37, 130.22, 128.28, 127.83,
125.47, 124.37, 122.97, 66.79, 56.52, 53.72, 53.55, 48.35,
29.67.
2-[2-(Dimethyloamino)ethyl]-6-chloro-2,7-dihydro-3H-dibenzo
[de,h]cynnoline-3,7-dione (6a). To the suspension of 3 (0.5g,
1.77 mM) in chloroform (30 mL), K2CO3 (1.5 g, 10.85 mM)
and 2-chloro-N,N-dimethylethylamine hydrochloride (1.4 g,
8.85 mM) were added, then the mixture was stirred at 40°C
for 24h (HPLC monitoring). The inorganic solid was filtered
and washed with chloroform (40mL). The organic layer was
evaporated to dryness, and product 6a was obtained as an
orange solid (0.56g, HPLC purity 90.5%, 86% yield). HR-
MS (ESI) Calcd for C19H16ClN3O2 [M + H]+: 354.1009.
2-[2-(Diethylamino)ethyl]-6-chloro-2,7-dihydro-3H-dibenzo
[de,h]cynnoline-3,7-dione (6d).
To the suspension of 3
(0.1g, 0.35mM) in chloroform (5mL) and MeOH (1mL),
K2CO3 (0.29g, 2.12mM) and 2-chloro-N,N-
1
Found: 354.1000; H NMR (CDCl3, 200MHz) δ 8.56 (d,
diethylethylamine hydrochloride (0.30g, 1.77mM) were
added, then the mixture was stirred at 50°C for 48h
(HPLC monitoring). The inorganic solid was filtered and
washed with chloroform (20mL). The organic residue was
evaporated to dryness. The product was purified by
column chromatography in the solvent system,
successively: chloroform, chloroform/methanol 80:1, to
afford compound 6d as an orange solid (0.110g, HPLC
purity 95%, 83% yield). HR-MS (ESI) Calcd for
1H, J= 8.4Hz), 8.50 (dd, 1H, J=1.1Hz, J=8.0Hz), 8.39
(dd, 1H, J=1.1Hz, J= 7.7 Hz), 7.95 (d, 1H, J= 8.4 Hz), 7.80
(ddd, 1H, J=1.5Hz, J= 7.3 Hz), 7.65 (ddd, 1H, J=1.4Hz,
J= 7.6 Hz), 4.51 (t, 2H, J=6.6Hz, J= 13.2 Hz), 2.95 (t, 2H,
J=6.5Hz, J=13.3 Hz), 2.36 (s, 6H); 13C NMR (CDCl3,
200MHz) δ 180.65, 158.37, 142.22, 135.78, 134.41, 133.73,
132.56, 132.46, 131.39, 130.16, 128.34, 127.80, 125.56,
124.36, 123.11, 57.38, 49.51, 45.56.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Cybulski, K. Sidoryk, A. Formela, O. Michalak, A. Rosa, K. Mróz, and W. Maruszak
Vol 000
C21H20ClN3O2 [M+H]+: 382.1322. Found: 382.1310; H
NMR (CDCl3, 500MHz) δ 8.58 (d, 1H, J=8.54Hz), 8.40
(dd, 1H, J=0.79Hz, J=8.14Hz), 8.33 (dd, 1H, J=0.8Hz,
J=7.95Hz), 7.92 (d, 1H, J=8.54Hz), 7.75–7.72 (m, 1H),
7.64–7.61 (m, 1H), 4.51 (t, 2H, J=6.9Hz, J=14.1Hz),
3.03 (t, 2H, J=6.9Hz, J=14.1Hz), 2.70–2.66 (m, 4H),
1.06 (s, 6H); 13C NMR (CDCl3, 500MHz) δ 180.67,
158.31, 142.22, 135.81, 134.32, 133.76, 132.52, 132.43,
131.38, 130.16, 128.28, 127.81, 125.51, 124.36, 123.08,
50.61, 49.54, 47.33, 11.94.
1
[7] Bhasin, D. k.; Etter, J. P.; Chettiar, S. N.; Mok, M.; Li, P. K.
Bioorg Med Chem Lett 2013, 23, 6864.
[8] Bu, X.; Chen, J.; Deady, L. W.; Smith, C. L.; Baguley, B. C.;
Greenhalgh, D.; Yang, S.; Denny, W. A. Bioorg Med Chem 2005, 13,
3657.
[9] Bu, X.; Deady, L. W.; Finlay, G. J.; Baguley, B. C.; Denny, W. A.
J Med Chem 2001, 44, 2004.
[10] Garcia-Vilas, J. A.; Quesada, A. R.; Medina, M. A. Sci Rep
2015, 5, 8021.
[11] Sakulpanich, A.; Gritsanapan, W. Southeast Asian J Trop Med
Public Health 2009, 40, 835.
[12] Singh, D. N.; Verma, N.; Raghuwanshi, S.; Shukla, P. K.;
Kulshreshtha, D. K. Bioorg Med Chem 2006, 16, 4512.
[13] Batista, R.; de Jesus Silva, A. Jr.; de Oliveira, A. B. Molecules
2009, 14, 3037.
[14] Huang, Q.; Lu, G.; Shen, H. M.; Chung, M. C.; Ong, C. N.
Med Res Rev 2007, 27, 609.
2-[2-(Piperidinamino)ethyl]-6-chloro-2,7-dihydro-3H-dibenzo
[de,h]cynnoline-3,7-dione (6e). To the suspension of 3 (0.1g,
0.35 mM) in chloroform (5mL) and MeOH (1mL), K2CO3
(0.29 g,
2.12 mM)
and
1-(2-chloroethyl)piperidine
[15] Wiseman, L. R.; Spencer, C. M. Drugs Aging 1997, 10, 473.
[16] Dunn, C. J.; Goa, K. L. Drugs Aging 1996, 9, 122.
[17] Faulds, D.; Balfour, J. A.; Chrisp, P.; Langtry, H. D. Drugs
1991, 41, 400.
[18] Stefanska, B.; Arciemiuk, M.; Bontemps-Gracz, M. M.;
Dzieduszycka, M.; Kupiec, A.; Martelli, S.; Borowski, E. Bioorg Med
Chem 2003, 11, 561.
[19] BS-154 SP. Z O.O. Gdansk, Poland, US 9,096,536 B2, 2015.
[20] Heller, G.; Schulke, K. Ber dd chem Ges 1908, 41, 3627.
[21] Castle, R. N.; Kudo, H.; Lee, M. L. Collect Czech Chem
Commun 1991, 56, 2269.
[22] Alfred Eckert D. R., German Patent 383030, 1921; Great Brit-
ain Patent 182487, 1921; Chem Abstr 1922, 16, 4214.
[23] B. Anilin & S. Fabrik, German Patent 259365, 1912; Chem
Abstr 1914, 8, 1190.
[24] Ullman, F.; Minajeff, W. Liebigs Ann 1912, 388, 217.
[25] Fischer, O.; Sapper, A.; et al. J Prakt Chem 1911, 83, 201.
[26] Elslager, E. F.; Weinstein, E. A.; Worth, D. F. J Med Chem
1964, 7, 493.
[27] Lee, D. G. Oxidation of Organic Compounds by Permanganate
Ion and Hexavalent Chromium; Open Court, Pub. Co.: La Salle, IL, 1980.
[28] Fatiadi, A. J. Synthesis 1987, 106, 85.
hydrochloride (0.33 g, 1.77mM) were added, then the
mixture was stirred at 40°C for 48h (HPLC monitoring).
The inorganic solid was filtered and washed with
chloroform (20 mL). The organic residue was evaporated to
dryness. The product was purified by column
chromatography (eluent:chloroform) to afford compound 6e
as an orange solid (0.170 g, HPLC purity 91.1%, 100%
yield). HR-MS (ESI) Calcd for C22H20ClN3O2 [M + H]+:
394.1322. Found: 394.1310; 1H NMR (CDCl3, 500MHz) δ
8.57 (d, 1H, J= 8.54 Hz), 8.45–8.42 (m, 1H), 8.35–8.32 (m,
1H), 7.92 (d, 1H, J=8.54Hz), 7.75–7.71 (m, 1H), 7.63–
7.60 (m, 1H), 4.52 (t, 2H, J=6.9Hz, J=14.1Hz), 2.93 (t,
2H, J=6.9Hz, J=14.0Hz), 2.58 (brs, 4H), 1.60–1.58 (m,
4H), 1.45–1.43 (m, 2H); 13C NMR (CDCl3, 500MHz) δ
180.64, 158.26, 142.21, 135.78, 134.32, 133.75, 132.53,
132.42, 131.36, 130.16, 128.29, 127.78, 125.52, 124.35,
123.11, 56.74, 54.72, 54.55, 48.96, 25.78, 24.16.
[29] Abell, R. D. J. Chem Soc 1951, 1379.
[30] Bastock, T. W.; Clark, J. H.; Martin, K.; Trenbirth, B. W.
Green Chem 2002, 4, 615.
[31] Shaikh, T. M.; Sudalai, A. Tetrahedron Lett 2005, 46, 5587.
[32] Shaikh, T. M. A.; Emmanuvel, L.; Sudalai, A. JOC 2006, 71,
5043.
[33] Naeimi, H.; Namdariyes, R. Dyes Pigm 2009, 81, 259.
[34] Du Pont. US, US 2,519,037, 1950.
[35] Brzezinski, J. Z.; Bzowski, H. B.; Epsztajn, J. Tetrahedron
1996, 52, 3261.
[36] Kaila, N.; Huang, A.; Moretto, A.; Follows, B.; Janz, K.;
Lowe, M.; Thomason, J.; Mansour, T. S.; Hubeau, C.; Page, K.; Morgan,
P.; Fish, S.; Xu, X.; Cara Williams, C.; Saiah, E. J Med Chem 2012, 55,
5088.
Acknowledgments. This work was supported by the National
Centre for Research and Development in Poland grant no.
INNOTECH-K2/IN2/82/183215/NCBR/13 and partly supported
in the framework of the statutory project funded by the Polish
Ministry of Science and Higher Education. The authors would
like to acknowledge M. Kubiszewski and P. Cmoch from the
R&D Analytical Department PRI for the NMR support.
REFERENCES AND NOTES
[37] Cesari, N.; Biancalani, C.; Vergelli, C.; Dal Piaz, V.; Graziano,
A.; Biagini, P.; Ghelardini, C.; Galeotti, N.; Giovannoni, M. P. J Med
Chem 2006, 49, 7826.
[38] Humne, V. T.; Konda, S. G.; Hasanzadeh, K.; Lokhande, P. D.
Chin Chem Lett 2011, 22, 1435.
[39] Cristau, H. J.; Cellier, P. P.; Spindler, J. F.; Taillefer, M. Chem
Eur J 2004, 10, 5607.
[40] Salvatore, R. N.; Yoon, C. H.; Jung, K. W. Tetrahedron 2011,
57, 7785.
[41] Russell Buchman, R.; Scozzie, J. A.; Ariyan, Z. S.; Heilman,
R. D.; Rippin, D. J.; Pyne, W. J.; Powers, L. J.; Matthews, R. J. J Med
Chem 1980, 23, 1398.
[42] Scholl, R.; Keller, A.; Meyer, K.; Penz, H. Justus Liebigs Ann
Chem 1934, 512, 30.
[1] Wolkenstein, K.; Schoefberger, W.; Müller, N.; Oji, T. J Nat
Prod 2009, 72, 2036.
[2] Huang, H.; Wang, F.; Luo, M.; Chen, Y.; Song, Y.; Zhang,
W.; Zhang, S.; Ju, J. J Nat Prod 2012, 75, 1346.
[3] Muangsin, N.; Wisetsakdakorn, W.; Chaichit, N.; Sihanonth,
P.; Petsom, A.; Sangvanich, P. Dyes Pigm 2008, 77, 653.
[4] Shamim, G.; Ranjan, S. K.; Pandey, D. M.; Ramani, R. Eur J
Entomol 2014, 111, 149.
[5] Anthraquinone The Complete Book on Natural Dyes &
PigmentsNIIR Board of Consultants & Engineers Ed.; Asia Pacific Busi-
ness Press Inc.: Delhi, India, 2005.
[6] Dave, H.; Ledvani, L. Indian J Nat Prod Resour 2012, 3, 291.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet