Oxidative coupling of acridinones: Synthesis of new C2-symmetry atropisomers

Article abstract of DOI:10.1002/jhet.5570450102

(Chemical Equation Presented) The preparation of symmetric 2,2′-dimethoxy-10,10′-biacridinyl-9,9′-dione atropisomers were obtained by the oxidative coupling of 9(10H)-acridinone with 1,3-dibromo-5,5-dimethyl-imidazolidine-2,4-dione.

Full text of DOI:10.1002/jhet.5570450102

Jan-Feb 2008
67
Oxidative Coupling of Acridinones: Synthesis of
New C2-Symmetry Atropisomers
Karine Scarpellini-Charras, Gérard Boyer,* Nathalie Filloux and Jean-Pierre Galy
UMR SYMBIO 6178, Université Paul Cézanne, Case 552, Faculté St-Jérôme,
13397 Marseille Cedex 20, France
E-mail: gerard.boyer@univ-cezanne.fr
Received January 28, 2005
O
R
OCH3
O
R
OCH3
N
N
N
H
H3CO
R
O
The preparation of symmetric 2,2'-dimethoxy-10,10'-biacridinyl-9,9'-dione atropisomers were obtained
by the oxidative coupling of 9(10H)-acridinone with 1,3-dibromo-5,5-dimethyl-imidazolidine-2,4-dione
J. Heterocyclic Chem., 45, 67 (2008).
6
3
COOH
1
Acridine derivatives are well known therapeutic
agents due to their wide range of pharmacological
and biological activities [1], and many C2-symmetry
derivatives have been reported in the literature [2].
We reported previously the prepartion of
symmetrical heterocyclic host compounds related to
bianthryl [3] using unsubstituted 9,9-biacridinyl [4];
but no inclusion compounds were observed with
these derivatives. On the other hand 2,2'-dimethoxy-
9,9'-biacridines atropisomers proved useful in
molecular recognition showing a 'scissor-like' host
conformation and guest inclusion of chloroform in
their crystalline structure [5]. Recently we obtained
the first chiral (aR)-(-)-9,9'-biacridinyl-2,2'-diol
atropisomer enantiomerically pure by derivatization
and recrystallisation [6]. Hence we were interested
in the preparation of new C2 symmetry derivatives
bridged at positions 10,10' and report now the
synthesis of 2,2'-dimethoxy-10,10'-biacridinyl-9,9'-
diones using the corresponding methoxy-9(10H)-
acridinones 4a and 4b.
4'
5
R1
R2
3'
R1
COOH
Br
R2
K2CO3, Cu
+
C2H5OH/
dimethoxyethane
3-4 h, reflux.
4
N
1'
H
H2N
2
2'
1a, R = H
1b, R = OCH3
2a, R2 = OCH3
2b, R2 = CH3
3a, R1 = H, R2 = OCH3, 83 %
3b, R1 = OCH3, R2 = CH3, 69 %
The cyclization of 3a,b could be performed by Friedel-
Crafts acylation in polyphosphoric acid or in sulfuric acid
but the best yields were obtained in polyphosphoric acid
after purification leading to 2-methoxy-9(10H)-acridinone
(4a) and 2-methoxy-7-methyl -9(10H)-acridinone (4b) in
65 % and 95 % yield respectively. Demethylation was
also observed performing the cyclization of anthranilic
acid (3b) in sulfuric acid; leading to the hydroxy
derivative 2-hydroxy-7-methyl-acridin-9(10H)-one (5) in
89 % yield (Scheme 2).
O
R
OCH3
polyphosphoric acid
3 hours, 120 °C
3a-b
3b
4a, R = H, 65 %
4b, R = CH3, 95 %
N
H
O
Our approach towards this synthesis was based on the
preparation of the 2-methoxy- and 2-methoxy-7-methyl-
9(10H)-acridinones (4a) and (4b) followed by oxidative
coupling to yield the desired acridinone dimers.
H3C
OH
sulfuric acid
5
N
H
1/ 0.5 hour,90°C
2/ 0.5 hour, 120 °C
89 %
First, 4'-methoxyphenyl-N-anthranilic acid (3a) and 5-
methoxy-4'-methyl-N-phenylanthranilic acid (3b) were
prepared by Ullmann's reaction between 2-bromo-benzoic
acid and 4-alkylanilines (2a) and (2b). Compound 3a was
obtained by a modified procedure of Krishnegowda using
EtOH as solvant and 2-bromobenzoïc acid [7]; while use
of dimethoxyethane instead of 1-pentanol under reflux
yielded 3b [8] (Scheme 1).
Then, we tried the oxidative homocoupling of 2-meth-
oxy-9(10H)-acridinone (4a) and 2-methoxy-7-methyl-
9(10H)-acridinone (4b), according to Graebe's procedure
with sodium bichromate in acetic acid [9] successfully
used in the laboratory for the preparation of 10,10'-
biacridinyl-9,9'-dione derivatives, [4] and also with
tris(acetyl-acetonato)cobalt(III), in deuteriodimethyl-

68
K. Scarpellini-Charras, G. Boyer, N. Filloux and J.-P. Galy
Vol 45
sulfoxide [10], but these methods did not lead to
satisfactory results. At the same time, benzylic photobro-
mination of 9-chloro-7-methoxy-2-methylacridine with N-
bromosuccinimide [11] and 1,3-dibromo-5,5-dimethyl-
imidazolidine-2,4-dione [12] was studied in the laboratory
to prepare polyacridinic ligands [13], and the best yields
were obtained using 1,3-dibromo-5,5-dimethyl-imidazol-
idine-2,4-dione instead of the commonly employed N-
bromosuccinimide in anhydrous carbon tetrachloride
under reflux (Scheme 3).
Table 1
Equivalents of 1,3-dibromo-5,5'-dimethylimidazolidine-2,4-dione for
the synthesis of 7a-c from 4a.
1,3-dibromo-5,5'-
Entry dimethylimidazolidine- Yield of 7a-c
2,4-dione equivalent
1
2
3
4
5
0.05
0.2
0.5
0.8
1.1
1.1
2
7a (50%)
7b (4%), 7e (10%)
7a (1%), 7b (6%), 7c (34%)
7a (1%), 7b (12%), 7c (33%
7a (1%), 7b (6%), 7c (34%)
mixture 7a/7b (55/45)[b]
7c (50%), mixture 7a/7b (40/60) [b]
6 [a]
7 [c]
O
1
8
2
OCH3
7
8a
9a
4a
1,3-dibromo-5,5-dimethyl
imidazolidine-2,4-dione
carbon tetrachloride
H3C
9
[a] No hꢁ irradiation, [b] isomers were not separated, [c] N-bromo-
succinimide was used instead 1,3-dibromo-5,5-dimethylimidazolidine-
2,4-dione.
10
N
6
3
10a
4b
5
4
N
3 hours, hn, 300 W
55%
6
H3CO
CH3
230-400 mesh). Melting points were determined with an
Electrothermal 9200 melting point apparatus and are
uncorrected. The H- and 13C-nmr spectra were measured on a
O
1
In the case of 4b, only one coupling product, the biacri-
dinyl-9,9'-dione (6) was obtained using 0.2 equivalent of
1,3-dibromo-5,5'-dimethylimidazolidine-2,4-dione, while
coupling and bromination of 4a gave a mixture of
acridinones 7a,c, (Scheme 4).
BRUKER AC 300 (300.13 MHz) spectrometer. Synchronous
excitation-emission fluorescence spectra were recorded with a
Perkin Elmer LS-50 spectrometer interfaced to a personal
computer. The source was a Xenon flash lamp, power equivalent
to 20 kW for 8 μs duration. Samples dissolved in DMF were
filled into a 10 mm fused quartz cell. All the spectra were
computed at 1 nm resolution between 200 to 600 nm. The
fluorescence spectra were collected by synchronous scanning the
excitation and emission monochromator in the 200 to 600 nm
range with constant wavelength difference ꢀꢁ= 30 nm between
them. The step size and band pass of the monochromator were
set to 5 and 4 nm respective1y.
4'-Methoxyphenyl-N-anthranilic acid (3a). A mixture of 2-
bromobenzoic acid (1a) (24.31 g, 0.12 mol), 4-methoxyaniline
(2a) (16 g, 0.13 mol), anhydrous potassium carbonate (41.4 g,
0.17 mol), and copper (0.35 g) in absolute ethanol (200 ml) was
heated under reflux with stirring for 4 hours, and the solvent was
removed in vacuo. The mixture was poured into hot water (400
mL) and filtered. The filtrate was acidified with diluted
hydrochloric acid (6 N) until pH 6 and filtered to yield 20.2 g
(83 %) of a green solid (3a), mp 186°C. TLC/Rf: 0.3
(methylenechloride/ethanol, 6/4). 1H-nmr (deuteriodimethyl
sulfoxide) ꢀ 3.75 (s, 3H, OCH3), 6.67 (ddd, J = 8.0, 7.0 and 0.9
Hz, 1H, H-5), 6.91 (dd, J = 0.9 and 8.3 Hz, 1H, H-3), 6.94 (dd, J
= 2.2 and 8.9 Hz, 2H, H-3'), 7.17 (dd, J = 2.1 and 8.9 Hz, 2 H,
H-2'), 7.31 (ddd, J = 1.6, 7.0 and 8.3 Hz, 1H, H-4), 7.85 (dd, J =
1.6 and 8.0 Hz, 1H, H-6), 9.42 (s, 1H, NH), 12.82 (s, 1H,
COOH). 13C-nmr (deuteriodimethyl sulfoxide) ꢀ 55.2 (OCH3),
111.2 (C-1), 112.8 (C-3), 114.8 (C-3'), 116.2 (C-5), 125.1 (C-2'),
131.7 (C-4), 132.9 (C-4'), 134.2 (C-6), 148.8 (C-2), 156.1 (C-1'),
170.0 (COOH). Anal. Calcd for C14H13NO3: C, 69.12; H, 5.39;
N, 5.76. Found: C, 69.23, H, 5.69, N, 5.54.
O
OCH3
1,3-dibromo-5,5-dimethyl
imidazolidine-2,4-dione
carbon tetrachloride
O
N
N
H3CO
Br
4a
1/ 0.5 hour, 80 °C
2/ 16.5 hours, hn, 300 W
+
N
H
H3CO
7b
O
O
9
7a
1
4
8
8a
2
Br
9a
4a
H3CO
7
10
N
6
3
5a
5
7c
+
N
Br
OCH3
O
However, desired 2,2'-dimethoxy-10,10'-biacri-dinyl-
9,9'-dione 7a was prepared selectively in 50 % yield using
0.05 molar equivalent of 1,3-dibromo-5,5'-dimethyl-
imidazolidine-2,4-dione, whereas mono and dibrominated
acridinones 7b and 7c were obtained, as shown in Table 1
In conclusion, we have reported the oxidative
preparation of a new class of C2-symmetry atropisomers
by the reaction of acridinones with 1,3-dibromo-5,5'-
dimethylimidazolidine-2,4-dione. Further studies of this
reaction are now currently in progress.
5-Methoxy-4'-methyl-N-phenylanthranilic acid (3b).
A
mixture of 2-bromo-5-methoxybenzoic acid (1b) (10 g, 0.043
mol), 4-toluidine (2b) (5.78 g, 54 mmol), anhydrous potassium
carbonate (7.44 g, 54 mmol), copper (1 g) and dimethoxyethane
(100 ml) was heated under reflux with stirring for 3 hours and
the solvent was removed in vacuo. The mixture was poured into
hot water (100 ml) and filtered. The filtrate was acidified with
diluted hydrochloric acid (6 N) until pH 8 and filtered. Then
EXPERIMENTAL
Thin-layer chromatography (TLC) carried out on aluminium
sheets coated with silica gel 60 (Merck 5554). Column
chromatography was performed on silica gel 60 (Merck 9385,

Jan-Feb 2008
Oxidative Coupling of Acridinones: Synthesis of New C2-Symmetry Atropisomers
69
more hydrochloric acid (6 N) was added to the filtrate until pH 4
to yield the anthranilic acid (3b) (7.62 g, 69 %) as a green solid,
mp 160°C. TLC/Rf: 0.4 (methylenechloride/ethanol, 7/3). H-
and filtered to yield 2.34 g (10.4 mmol, 89 %) of 5 as a green
powder, mp 225 °C. TLC/Rf: 0.5 (methylenechloride/ethanol,
7/3). H-nmr (deuteriodimethyl sulfoxide) ꢀ 2.38 (s, 3H, CH3),
1
1
nmr (deuteriodimethyl sulfoxide) ꢀ 2.32 (s, H, CH3), 3.78 (s, 3H,
OCH3), 6.99 (dd, J = 3.0 and 9.5 Hz, 1H, H-4), 7.08 (d, J = 6.1
Hz, 2H, H-2'), 7.13 (d, J = 6.1 Hz, 2H, H-3'), 7.14 (d, J = 9.5 Hz,
1H, H-3), 7.49 (d, J = 3.0 Hz, 1H, H-6). 13C-nmr (deuterio-
dimethyl sulfoxide) ꢀ 20.8 (CH3), 55.8 (OCH3), 110.5 (C-1),
113.9 (C-6), 116.2 (C-4), 122.5 (C-2'), 124.3 (C-3), 129.9 (C-3'),
133.1 (C-4'), 138.4 (C-2), 144.0 (C-1'), 150.8 (C-5), 173.5
(COOH). Anal. Calcd for C15H15NO3: C, 70.02; H, 5.88; N, 5.44.
Found: C, 70.29; H, 5.98; N, 5.61.
7.24 (dd, 1H, J = 2.8 and 8.9 Hz, H-3), 7.39 (d, 1H, J = 8.3 Hz,
H-5), 7.42 (d, 1H, J = 8.9 Hz, H-4), 7.49 (dd, 1H, J = 1.9 and 8.5
Hz, H-6), 7.52 (d, 1H, J = 2.6 Hz, H-1), 7.96 (s, 1H, H-8), 9.51
(s, 1H, OH), 11.49 (s, 1H, NH). 13C-nmr (deuteriodimethyl
sulfoxide) ꢀ 20.7 (CH3), 108.1 (C-1), 117.2 (C-5), 118.8 (C-4),
119.3 (C-9a), 121.4 (C-8a), 124.0 (C-3), 124.9 (C-8), 129.3 (C-
7), 134.4 (C-6), 134.6 (C-4a), 138.7 (C-5a), 151.7 (C-2), 176.0
(C-9). Anal. Calcd for C14H11NO2: C, 74.65; H, 4.92; N, 6.22.
Found: C, 74.33; H, 4.81; N, 6.48.
2-Methoxy-9(10H)-acridinone (4a).
A mixture of 4'-
2,2'-Dimethoxy-7,7'-methyl-10,10'-biacridinyl-9,9'-dione (6).
In a 250 mL pyrex bottle flak, 2-methyl-7-methoxy-9(10H)-
acridinone (4b) (8.37 mmol) was dissolved in freshly distilled
carbon tetrachloride (100 mL) at 80 °C under nitrogen
atmosphere. 1,3-Dibromo-5,5'-dimethyl-imidazolidine-2,4-dione,
(1.92 g, 6.71 mmol, 0.2 equiv.) was added and the mixture was
irradiated for 3 h under stirring with a 300 W halogen
floodlamp. Then the solvent was removed in vacuo and the
residue was chromatographied on silica gel (chloroform/ethyl
acetate: 3/2) to yield 6, as a yellow powder (1.10 g, 55 %), mp
205 °C (from ethanol). TLC/Rf: 0.5 (chloroform/ethyl acetate
methoxyphenylanthranilic acid (3a) (15.4 g, 63 mmol) and 154 g
(1.08 mol) of polyphosphoric acid were heated for 3 h at 120 °C.
The mixture was poured into cold water (200 ml) to yield a
green precipitate witch was basified until pH = 8 with
ammonium hydroxide (10 %), filtered and dried. The recovered
powder was then added to hot ethanol (400 mL), and warmed
one night under stirring. The solution was filtered hot and water
was added (100 mL) to yield a yellow precipitate witch was
collected by filtration and dried to yield 9.3 g (65 %) of 4a, mp
1
260°C. TLC/Rf: 0.3 (methylenechloride/ethanol, 6/4). H-nmr
1
(deuteriodimethyl sulfoxide) ꢀ 3.85 (s, 3 H, OCH3), 7.21 (ddd,
1H, J = 1.0, 7.0 and 8.0 Hz, H-7), 7.40 (dd, 1H, J = 2.9 and 9.1
Hz, H-3), 7.52 (dd, 1H, J = 1.0 and 8.3 Hz, H-5), 7.53 (dd, 1H, J
= 9.1 Hz, H-4), 7.62 (d, 1H, J = 2.9 Hz, H-1), 7.69 (ddd, 1H, J =
1.3, 7.0 and 8.3 Hz, H-6), 8.22 (dd, 1H, J = 1.3 and 8.0 Hz, H-8),
11.73 (s, 1H, NH). 13C-nmr (deuteriodimethyl sulfoxide) ꢀ 55.35
(OCH3), 104.8 (C-1), 117.3 (C-7), 119.2 (C-4), 119.6 (C-9a),
120.7 (C-7), 121.0 (C-8a), 124.3 (C-3), 125.9 (C-8), 133.0 (C-6),
135.7 (C-4a), 140.4 (C-5a), 153.9 (C-2), 175.1 (C-9). Anal.
Calcd for C14H11NO2: C, 74.65; H, 4.92; N, 6.22. Found: C,
74.87; H, 4.75; N, 6.40.
3/2). H-nmr (deuteriodimethyl sulfoxide) ꢀ 2.40 (s, 6H, CH3),
3.86 (s, 6H, OCH3), 6.70 (d, 2H, J = 8.5 Hz, H-5), 6.75 (d, 2H, J
= 9.1 Hz, H-4), 7.24 (dd, 2H, J = 2.8 and 9.1 Hz, H-3), 7.42 (dd,
2H, J = 2.0 and 8.5 Hz, H-6), 7.85 (d, 2H, J = 2.8 Hz, H-1), 8.25
(sbr, 2H, H-8). 13C-nmr (deuteriodimethyl sulfoxide) ꢀ 20.3
(CH3), 55.6 (OCH3), 107.4 (C-1), 113.7 (C-5), 115.7 (C-4),
121.2 (C-9a), 122.8 (C-8a), 124.7 (C-3), 126.6 (C-8), 132.6 (C-
7), 135.2 (C-4a), 136.4 (C-6), 138.6 (C-5a), 155.4 (C-2), 175.8
(C-9). Anal. Calcd for C30H24N2O4: C, 75.61; H, 5.08; N, 5.88.
Found: C, 75.86; H, 5.28; N, 5.63.
General procedure for preparation of (7a-c). A mixture of
2-methoxy-9(10H)-acridinone (4a) (1 g, 4.44 mmol), 1,3-
dibromo-5,5-dimethyl-imidazolidine-2,4-dione, (0.05-2 equiv.),
and freshly distilled carbon tetrachloride (50 mL) was heated
under stirring at 80°C for 0.5 hour and then was irradiated with a
300 W halogen floodlamp for 16.5 hours. The solvent was
removed in vacuo. The residue was dissolved in chloroform and
filtered. The filtrate was evaporated to yield a crude mixture
which was chromatographied on silicagel with chloroform as the
eluant to yield the corresponding mono or bisacridinones (7a-c)
as yellow solids.
2-Methoxy-7-methyl-9(10H)-acridone (4b). One g (3.9 mmol)
of 5-methoxy-4'-methyl-N-phenyl anthranilic acid (3b) and 7 g
(49 mmol) of polyphosphoric acid were heated for 3 h at 120 °C.
The dark mixture was then poored on ice. The obtained solution
was basified until pH = 8 with ammonium hydroxide (10 %). The
yellow precipitate was collected by filtration, washed with water
and dried. The crude solid was washed in hot ethanol (50 ml). The
residue was filtered hot, washed with two portions (10 ml) of hot
ethanol and dried to give 0.88 g (3.7 mmol, 95 %) of 4b as a
yellow powder, mp 300 °C. TLC/Rf: 0.3 (methylenechloride/
1
ethanol, 7/3). H-nmr (deuteriodimethyl sulfoxide) ꢀ 2.40 (s, 3H,
2,2'-Dimethoxy-10,10'-biacridinyl-9,9'-dione (7a). With
1,3-dibromo-5,5-dimethyl-imidazolidine-2,4-dione, (0.05 equiv.,
0.22 mmol). Mp 381 °C (from ethanol). TLC/Rf: 0.5 (chloro-
CH3), 3.84 (s, 3H, OCH3), 7.37 (dd, 1H, J = 2.9 and 8.9 Hz, H-3),
7.43 (d, 1H, J = 8.6 Hz, H-5), 7.50 (d, 1H, J = 8.6 Hz, H-4), 7.52
(dd, 1H, J = 1.9 and 8.4 Hz, H-6), 7.60 (d, 1H, J = 2.7 Hz, H-1),
8.01 (s, 1H, H-8), 11.64 (s, 1H, NH). 13C-nmr (deuteriodimethyl
sulfoxide) ꢀ 20.6 (CH3), 55.3 (OCH3), 104.7 (C-1), 117.3 (C-5),
119.1 (C-4), 119.5 (C-9a), 120.8 (C-8a), 124.1 (C-3), 124.9 (C-8),
129.7 (C-7), 134.5 (C-6), 135.7 (C-4a), 138.6 (C-5a), 153.7 (C-2),
176.2 (C-9). Anal. Calcd for C15H13NO2: C, 75.30; H, 5.48; N,
5.85. Found: C, 75.59; H, 5.63; N, 5.60.
2-Hydroxy-7-methylacridin-9(10H)-one (5). A mixture of 5-
methoxy-4'-methyl-N-phenyl-anthranilic acid (3b) (3 g, 11.7
mmol) and sulfuric acid (30 mL, 95 %) was heated at 90°C
under stirring for 0.5 hour, then at 120°C for 0.5 hour more. The
green solution was added to cold water (300 mL) and basified
until pH = 8 with ammonium hydroxide (10 %). The green
precipitate was collected by filtration, washed with water and
dried. The crude residue was washed with hot toluene (60 mL)
1
form). H-nmr (deuteriochloroform) ꢀ 3.92 (s, 3H, OCH3), 6.65
(d, 2H, J = 9.2 Hz, H-4), 6.69 (dd, 2H, J = 1.0 and 8.5 Hz, H-5),
7.13 (dd, 2H, J = 3.0 and 9.2 Hz, H-3), 7.36 (ddd, 2H, J = 8.2,
1.0 and 7.9 Hz, H-7), 7.50 (ddd, 2H, J = 1.7, 8.2 and 8.5 Hz, H-
6), 8.03 (d, 2H, J = 3.0 Hz, H-1), 8.65 (dd, 2H, J = 1.7 and 7.9
Hz, H-8). 13C-nmr (deuteriochloroform) ꢀ 56.1 (OCH3), 107.9
(C-1), 113.6 (C-5), 115.6 (C-4), 122.0 (C-8a), 123.4 (C-9a),
123.4 (C-7), 128.5 (C-8), 135.0 (C-6), 135.7 (C-4a), 156.3 (C-2),
177.1 (C-9). Anal. Calcd for C28H20N2O4: C, 74.99; H, 4.50; N,
6.25. Found: C, 75.23; H, 4.31; N, 6.10.
2-Bromo-7-methoxyacridin-9(10H)-one (7b). With 1,3-
dibromo-5,5-dimethyl-imidazolidine-2,4-dione, (0.5 equiv., 2.22
mmol). Mp 337 °C (from ethanol), litt. 337-339°C (from acetic
1
acid) [14]. TLC/Rf: 0.4 (chloroform). H-nmr (deuteriodimethyl
sulfoxide) ꢀ 3.84 (s, 3H, OCH3), 7.42 (dd, 1H, J = 8.7 et 2.8 Hz,

70
K. Scarpellini-Charras, G. Boyer, N. Filloux and J.-P. Galy
Vol 45
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24, 977.
H-6), 7.50 (d, 1H, J = 8.9 Hz, H-4), 7.53 (d, 1H, J = 8.7 Hz, H-
5), 7.60 (d, 1H, J = 2.8 Hz, H-8), 7.81 (dd, 1H, J = 2.3 and 8.9
Hz, H-3), 8.28 (d, 1H, J = 2.3 Hz, H-1), 11.90 (s, 1H, NH). 13C-
nmr (CDCl3) ꢀ 55.6 (OCH3), 105.0 (C-8), 113.0 (C-2), 119.6 (C-
5), 120.2 (C-4), 121.0 (C-9a), 121.1 (C-8a), 125.0 (C-6), 128.0
(C-1), 135.8 (C-3), 135.8 (C-5a), 139.4 (C-4a), 154.5 (C-7),
175.2 (C-9). Anal. Calcd for C14H10BrNO2: C, 55.48; H, 3.31; N,
4.61. Found: C, 55.25; H, 3.59; N, 4.80.
2,2'-Dibromo-7,7'-dimethoxy-10,10'-biacridinyl-9,9'-dione
(7c). With 1,3-dibromo-5,5-dimethyl-imidazolidine-2,4-dione,
(2 equiv., 8.88 mmol). Mp 264 °C (from ethanol). TLC/Rf: 0.6
1
(chloroform). H-nmr (CDCl3) ꢀ 3.92 (s, 6H, OCH3), 6.57 (d,
2H, J = 9.2 Hz, H-4), 6.62 (d, 2H, J = 8.9 Hz, H-5), 7.15 (dd,
2H, J = 2.9 and 9.2 Hz, H-3), 7.56 (dd, 2H, J = 2.2 and 8.9 Hz,
H-6), 8.00 (d, 2H, J = 2.9 Hz, H-1), 8.75 (d, 2H, J = 2.2 Hz, H-
8). 13C-nmr (CDCl3) ꢀ 56.1 (OCH3), 108.0 (C-1), 115.4 (C-4),
115.4 (C-5), 117.0 (C-7), 123.1 (C-9a), 123.4 (C-8a), 126.0 (C-
3), 131.0 (C-8), 135.2 (C-4a), 137.9 (C-6), 139.4 (C-5a), 156.62
(C-2), 175.7 (C-9). Anal. Calcd for C28H18Br2N2O4: C, 55.47; H,
2.99; N, 4.62. Found: C 55.66, H 3.18, N 4.83.
REFERENCES
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C. G.; Hammer, G.; Blau, N. F. J. Org. Chem. 1957, 22, 1678.
[13] Filloux, N.; Galy, J.-P. Synlett 2001, 7, 1137.
[14] Bogucka, M.; Ledochowski, Z. Roczniki Chemii, 1966, 40,
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