Synthesis and cytotoxic activity of benzophenanthrolinone analogues of acronycine

Article abstract of DOI:10.1248/cpb.49.1077

Condensation of either 2-bromobenzoic acid (4) or 2-chloro-3-nitrobenzoic acid (5) with suitable amino-quinolines 6 - 8 afforded phenylquinolylamines 9 - 13. Acid mediated cyclizafion gave the corresponding 12H-benzo[b][1,7]phenanthrolin-7-ones 14 and 15, and 12H-benzo[b][1,10]phenanthrolin-7-ones 16 - 18. Compounds 14, 16, and 17 were subsequently N-methylated to 6-demethoxyacronycine and acronycine analogues 19 - 21, whereas reduction of the aromatic nitro group of 18 gave the amino derivative 22. Unsubstituted 12H-benzo[b][1,10]phenanthrolin-7-ones 16, 17, 20, and 21 were devoid of significant cytotoxic activity, whereas 18 and 22, bearing a nitrogen substituent at position 11, were significantly active. Unsubstituted 12H-benzo[b][1,7]phenanthrolin-7-ones 14 and 19, which include a pyridine nitrogen in the same 4-position as the pyran oxygen of acronycine exhibited cytotoxic activities within the same range of magnitude as acronycine itself.

Full text of DOI:10.1248/cpb.49.1077

September 2001
Chem. Pharm. Bull. 49(9) 1077—1080 (2001)
1077
Synthesis and Cytotoxic Activity of Benzophenanthrolinone Analogues of
Acronycine
a
a
Jean-Bernard BONGUI, Abdelhakim ELOMRI, Elisabeth SEGUIN, ,a François TILLEQUIN,b
*
Bruno PFEIFFER,c Pierre RENARD,c Alain PIERRE´,d and Ghanem ATASSI
d
Laboratoire de Pharmacognosie de l’Université de Rouen-Haute Normandie,a Faculté de Pharmacie, 22, Boulevard
Gambetta, F-76183 Rouen Cedex, France, Laboratoire de Pharmacognosie de l’Université René Descartes,b
U.M.R./C.N.R.S. n°8638, Faculté des Sciences Pharmaceutiques et Biologiques, 4, Avenue de l’Observatoire, F-75006
Paris, France, A.D.I.R. et Compagnie,c 1 rue Carle Hébert, F-92415 Courbevoie Cedex, France, and Institut de Recherche
Servier,d 11 rue des Moulineaux, F-92150 Suresnes, France. Received February 13, 2001; accepted May 21, 2001
Condensation of either 2-bromobenzoic acid (4) or 2-chloro-3-nitrobenzoic acid (5) with suitable amino-
quinolines 6—8 afforded phenylquinolylamines 9—13. Acid mediated cyclization gave the corresponding 12H-
benzo[b][1,7]phenanthrolin-7-ones 14 and 15, and 12H-benzo[b][1,10]phenanthrolin-7-ones 16—18. Compounds
14, 16, and 17 were subsequently N-methylated to 6-demethoxyacronycine and acronycine analogues 19—21,
whereas reduction of the aromatic nitro group of 18 gave the amino derivative 22. Unsubstituted 12H-
benzo[b][1,10]phenanthrolin-7-ones 16, 17, 20, and 21 were devoid of significant cytotoxic activity, whereas 18
and 22, bearing a nitrogen substituent at position 11, were significantly active. Unsubstituted 12H-
benzo[b][1,7]phenanthrolin-7-ones 14 and 19, which include a pyridine nitrogen in the same 4-position as the
pyran oxygen of acronycine exhibited cytotoxic activities within the same range of magnitude as acronycine itself.
Key words acronycine; benzophenanthrolinone; cytotoxicity
The acridone alkaloid acronycine (1), which was first iso- throlin-7-ones 14 and 15, and 12H-benzo[b][1,10]phenan-
lated from Acronychia baueri SCHOTT (Rutaceae) in 1948, throlin-7-ones 16—18 was obtained by use of trifluoroacetic
was later found to be a potent anticancer agent.1—5) It is of in- anhydride21,23) or concentrated sulfuric acid.20,24) Methylation
terest because of its activity against a broad spectrum of solid at N-12 using methyl iodide under classical or phase-transfer
tumors, including numerous sarcomas, myelomas, carcino- catalyzed conditions21,23) could only be ensured in the cases
mas, and melanomas.2—6) Nevertheless, its low water-solubil- of compounds 14, 16, and 17, which bear no bulky nitro sub-
ity and moderate potency have severely hampered its clinical stitutent at C-11. This reaction gave access to 6-demethoxy-
trials, which have given so far only poor results.7) Conse- acronycine analogues 12-methyl-12H-benzo[b][1,7]phenan-
quently, the development of structural analogues possessing a throlin-7-one (19) and 12-methyl-12H-benzo[b][1,10]phenan-
basic nitrogen atom able to give water-soluble salts seems throlin-7-one (20), and to acronycine analogue 6-methoxy-
highly desirable.8,9)
12-methyl-12H-benzo[b][1,10]phenanthrolin-7-one (21). Re-
The replacement of the dimethylpyran D ring of acrony- duction of the nitro group of 18 by catalytic hydrogenation
cine by a pyridine unit, present in numerous tetracyclic anti- gave 11-amino-12H-benzo[b][1,10]phenanthrolin-7-one (22).
tumor drugs including the linear ellipticines10—12) and oliva- In contrast, all attempts towards the reduction of the nitro
cines,13—15) and their angular 7H- and 11H-pyridocarbazoles group of 15 failed, most probably due to the almost complete
counterparts,16—19) appeared to us an attractive way to look insolubility of this compound in usual organic solvents.
for new anticancer candidates. In addition, this approach was
consistent with the antitumor activities of several recently de- the new benzophenanthrolin-7-one derivatives was carried
scribed benzophenanthrolinones related to amsacrine.20)
out in vitro on L1210 murine leukemia cell line. The results
This paper deals with the synthesis and cytotoxic proper- (IC50) are reported in Table 1.
Pharmacology The study of the biological properties of
ties of 12H-benzo[b][1,7] and [1,10]phenanthrolinones re-
lated to acronycine, and also to 6-demethoxyacronycine (2) 19 were as potent as acronycine. In the 12H-benzo[b][1,10]-
and 11-aminoacronycine (3), which were shown to exhibit
cytotoxic activities within the same range of magnitude as
acronycine itself.9,21)
The two 12H-benzo[b][1,7]phenanthrolin-7-ones 14 and
Chemistry The key-step of our approach was an Ull-
mann condensation22) of either 2-bromobenzoic acid (4) or 2-
chloro-3-nitrobenzoic acid (5) with suitable aminoquinolines
6—8, to afford the carboxylic phenylquinolylamines 9—13.
Cyclization to the corresponding 12H-benzo[b][1,7]phenan-
Chart 1
Table 1. Cytotoxic Activities of Benzophenanthrolinones 14—22 Compared with Acronycine Derivatives 1—3
Compound
1
2
3
14
15
16
17
18
19
20
21
22
IC50 (mM) L1210 cells
a) ins: insoluble.
10.4
29.9
18.8
15
insa)
Ͼ100
33
7.7
10.7
72.1
80.8
25.4
To whom correspondence should be addressed. e-mail: Elisabeth.Seguin@univ-rouen.fr
© 2001 Pharmaceutical Society of Japan

1078
Vol. 49, No. 9
Chart 2
phenanthrolin-7-one series, compounds 18 and 22 were sig-
nificantly active, whereas 16, 17, 20, and 21 were devoid of
antiproliferative activity.
Results and Discussion
Considering the structure-activity relationships, it appears
that in the 12H-benzo[b][1,10]phenanthrolin-7-one series, only
compounds 18 and 22, bearing a nitrogen substitutent at po-
sition 11, exhibited significant cytotoxic activity. Unsubsti-
tuted compounds 16, 17, 20, and 21 were devoid of signifi-
cant activity. Surprisingly, it should be noted that compound
16, previously prepared as an intermediate in the course of
the preparation of amsacrine analogues, was reported to be
highly cytotoxic.20)
Interestingly, 12H-benzo[b][1,7]phenanthrolin-7-ones 14
and 19, which include a pyridine nitrogen in the same 4-posi-
tion as the pyran oxygen of acronycine exhibited cytotoxic
activities within the same range of magnitude as acronycine
itself. The position of the heteroatom in the heterocyclic D
ring fused onto the A–B–C acridone tricyclic system there-
fore appears to have a dramatic influence on the cytotoxic ac-
tivity.
Experimental
Chemistry Mass spectra were recorded with a Nermag R-10-10C spec-
trometer using electron impact (MS) and/or desorption chemical ionization
(DCI-MS; reagent gas: NH3) techniques. UV spectra (lmax in nm) were de-
termined in spectroscopic grade MeOH on a Beckman Model 34 spec-
trophotometer. IR spectra (nmax in cmϪ1) were obtained in potassium bro-
Chart 3
1
mide pellets on a Perkin-Elmer 257 instrument. H-NMR (d [ppm], J [Hz])
and 13C-NMR spectra were recorded at 300 MHz and 75 MHz, respectively,
using a Bruker AC-300 spectrometer. Column chromatography was con-
ducted using flash silica gel 60 Merck (40—63 mm) with an overpressure of
300 mbars.
7.53 (dd, 1H, Jϭ8; 5 Hz, C3Ј-H), 7.57 (dd, 1H, Jϭ8; 2 Hz, C6Ј-H), 7.73 (t,
1H, Jϭ8 Hz, C7Ј-H), 7.85 (dd, 1H, Jϭ8; 2 Hz, C8Ј-H), 7.96 (dd, 1H, Jϭ8; 2
Hz, C6-H), 8.35 (dd, 1H, Jϭ8; 2 Hz, C4Ј-H), 8.95 (dd, 1H, Jϭ5; 2 Hz, C2Ј-
H), 11.20 (br s, 1H, D2O exch., COOH), 13.10 (br s, 1H, D2O exch., NH).
13C-NMR (75 MHz, DMSO-d6) d: 113.8 (s, C-1), 115.2 (d, C-3), 118.7 (d,
C-5), 120.6 (d, C-6Ј), 124.7 ((s, C-4Јa), (d, C-3Ј)), 126.4 (d, C-8Ј), 130.7 (d,
C-7Ј) 131.6 (d, C-4Ј), 132.9 (d, C-6), 135.3 (d, C-4), 137.8 (s, C-5Ј), 149.2
(s, C-2), 150.0 (s, C-8Јa), 151.8 (d, C-2Ј), 171.4 (s, COOH). MS m/z: 264
(Mϩ), 249, 219. Anal. Calcd for C16H12N2O2: C, 72.71; H, 4.58; N, 10.60.
Found: C, 72.88; H, 4.50; N, 10.45.
3-Nitro-N-(5-quinolyl)anthranilic Acid (10): Treatment of 6 (175 mg, 1.21
mmol) with 2-chloro-3-nitrobenzoic acid (5) (246 mg, 1.22 mmol) under the
conditions previously described for 9 afforded 10 (226 mg, 60%) as yellow
crystals, mp: 205—206 °C. IR (KBr) cmϪ1: 3200—2850, 1630, 1620, 1560,
1350. UV lmax (MeOH) nm (log e): 233 (3.75), 280 (3.68). H-NMR (300
MHz, DMSO-d6) d: 6.79 (dd, 1H, Jϭ8; 2 Hz, C6Ј-H), 7.32 (t, 1H, Jϭ8, C5-
H), 7.56 (dd, 1H, Jϭ8; 5 Hz, C3Ј-H), 7.70 (t, 1H, Jϭ8 Hz, C7Ј-H), 7.82 (dd,
N-(5-Quinolyl)anthranilic Acid (9): A mixture containing 5-aminoquino-
line (6) (216 mg, 1.5 mmol), 2-bromobenzoic acid (4) (301.5 mg, 1.5 mmol),
potassium acetate (438 mg, 4.47 mmol), copper(II) acetate monohydrate (12
mg, 0.06 mmol), triethylamine (0.25 ml, 1.77 mmol), and 2-propanol (8 ml)
was stirred and heated under reflux for 24 h. After cooling and evaporating
the solvent, the residue was treated with 1 N HCl (30 ml) and extracted with
CH2Cl2 (3ϫ25 ml). The organic layer was separated, dried over anhydrous
Na2SO4, filtered, and evaporated under reduced pressure. Column chro-
matography on silica gel (CH2Cl2/MeOH : 80/20) followed by crystallization
from methanol gave 9 (213 mg, 53%) as yellow crystals, mp: 262—263 °C.
IR (KBr) cmϪ1: 3240, 3020, 1680, 1600. UV lmax (MeOH) nm (log e): 264
1
1
(4.19), 342 (3.65). H-NMR (300 MHz, DMSO-d6) d: 6.78 (td, 1H, Jϭ8; 2
Hz, C5-H), 6.93 (dd, 1H, Jϭ8; 2 Hz, C3-H), 7.32 (td, 1H, Jϭ8; 2 Hz, C4-H),

September 2001
1079
C16H10N2O: C, 78.03; H, 4.09; N, 11.37. Found: C, 78.20; H, 4.00; N, 11.49.
11-Nitro-12H-benzo[b][1,7]phenanthrolin-7-one (15): Cyclization of 10
(187 mg, 0.60 mmol) under conditions similar to those described for the
preparation of 14 afforded 15 (152 mg, 87%) as yellow crystals, mp: 290—
291 °C. IR (KBr) cmϪ1: 3200—2900, 1680, 1500, 1290. UV lmax (MeOH)
1H, Jϭ8; 2 Hz, C8Ј-H), 7.90 (dd, 1H, Jϭ8; 2 Hz, C6-H), 8.35 (dd, 1H, Jϭ8;
2 Hz, C4-H), 8.37 (dd, 1H, Jϭ8; 2 Hz, C4Ј-H), 8.94 (dd, 1H, Jϭ5; 2 Hz,
C2Ј-H), 12.41 (br s, 1H, D2O exch., COOH), 13.62 (br s, 1H, D2O exch.,
NH). 13C-NMR (75 MHz, DMSO-d6) d: 119.3 (d, C-5), 121.0 (d, C-6Ј),
122.1 (d, C-8Ј), 123.4 (s, C-1), 123.9 (s, C-4Јa), 124.3 (d, C-3Ј), 124.6 (d, C-
7Ј), 127.1 (d, C-4), 131.9 (s, C-4Ј), 137.2 (s, C-5Ј), 137.4 (d, C-6), 139.0 (s,
C-2), 140.2 (s, C-3), 149.9 (s, C-8Јa), 151.2 (d, C-2Ј), 170.8 (s, COOH). MS
m/z: 309 (Mϩ), 264. Anal. Calcd for C16H11N3O4: C, 62.14; H, 3.58; N,
13.59. Found: C, 62.55; H, 3.46; N, 13.42.
N-(8-Quinolyl)anthranilic Acid (11): 8-Aminoquinoline (7) (216 mg, 1.5
mmol) was reacted with 4 under conditions similar to those described for the
preparation of 9 to afford 11 (163 mg, 41%) as yellow crystals, mp: 266—
267 °C. IR (KBr) cmϪ1: 3200—3000, 1670, 1600. UV lmax (MeOH) nm (log
e): 244 (4.08), 261 (4.30), 378 (3.04). 1H-NMR (300 MHz, DMSO-d6) d:
6.95 (td, 1H, Jϭ8; 2 Hz, C5-H), 7.51 (m, 2H, C4-H, C7Ј-H,), 7.54 (t, 1H,
Jϭ8 Hz, C6Ј-H), 7.60 (dd, 1H, Jϭ8; 5 Hz, C3Ј-H), 7.75 (dd, 1H, Jϭ8; 2 Hz,
C5Ј-H), 7.77 (dd, 1H, Jϭ8; 2 Hz, C3-H), 7.79 (dd, 1H, Jϭ8; 2 Hz, C6-H),
8.35 (dd, 1H, Jϭ8; 2 Hz, C4Ј-H), 8.90 (dd, 1H, Jϭ5; 2 Hz, C2Ј-H), 11.00 (br
s, 1H, D2O exch., COOH), 13.10 (br s, 1H, D2O exch., NH). 13C-NMR (75
MHz, DMSO-d6) d: 112.7 (d, C-3), 116.8 (d, C-5Ј), 117.7 (s, C-1), 120.0 (d,
C-5), 120.2 (d, C-7Ј), 123.2 (d, C-3Ј), 128.0 (d, C-4), 128.7 (s, C-4Јa), 133.1
(d, C-6), 134.9 (d, C-6Ј), 137.4 (d, C-4Ј), 138.8 (s, C-8Ј), 140.4 (s, C-8Јa),
145.5 (s, C-2), 149.6 (d, C-2Ј), 170.2 (s, COOH). MS m/z: 264 (Mϩ), 249,
219. Anal. Calcd for C16H12N2O2: C, 72.71; H, 4.58; N, 10.60. Found: C,
72.80; H, 4.37; N, 10.75.
1
nm (log e): 237 (3.62), 283 (3.49). H-NMR (300 MHz, DMSO-d6) d: 7.50
(t, 1H, Jϭ8 Hz, C9-H), 7.74 (dd, 1H, Jϭ8; 5 Hz, C2-H), 8.04 (d, 1H, Jϭ9
Hz, C5-H), 8.67 (d, 1H, Jϭ9 Hz, C6-H), 8.71 (dd, 1H, Jϭ8; 2 Hz, C3-H),
8.83 (dd, 1H, Jϭ8; 2 Hz, C10-H), 8.98 (dd, 1H, Jϭ8; 2 Hz, C8-H), 9.18 (dd,
1H, Jϭ5; 2 Hz, C1-H), 11.04 (br s, 1H, D2O exch., NH). 13C-NMR (75
MHz, DMSO-d6) e: 116.4 (s, C-12b), 121.1 (d, C-5), 121.9 (d, C-2), 125.6
(d, C-9), 125.7 (s, C-6a), 126.5 (d, C-6), 129.2 (d, C-8), 130.7 (s, C-7a),
131.4 (d, C-1), 136.4 (d, C-10), 141.5 (s, C-12a), 143.9 (s, C-11a), 146.1 (s,
C-11), 151.4 (s, C-4a), 153.0 (d, C-3), 174.1 (s, C-7). MS m/z: 291 (Mϩ).
Anal. Calcd for C16H9N3O3: C, 65.98; H, 3.11; N, 14.43. Found: C, 65.72; H,
3.02; N, 14.26.
12H-Benzo[b][1,10]phenanthrolin-7-one (16): Cyclization of 11 (140 mg,
0.53 mmol) under conditions similar to those described for the preparation
of 14 afforded 16 (80 mg, 61%) as yellow crystals, mp: 271—272°C. IR
(KBr) cmϪ1: 3000—2900, 1640. UV lmax (MeOH) nm (log e): 265 (4.11),
295 (3.90), 320 (3.77), 355 (3.52), 383 (3.32). 1H-NMR (300 MHz, DMSO-
d6) d: 7.36 (td, 1H, Jϭ8; 1 Hz, C9-H), 7.66 (d, 1H, Jϭ9 Hz, C5-H), 7.75 (td,
1H, Jϭ8; 1 Hz, C10-H), 7.82 (dd, 1H, Jϭ8; 5 Hz, C3-H), 8.22 (dd, 1H, Jϭ8;
1 Hz, C11-H), 8.26 (d, 1H, Jϭ9 Hz, C6-H), 8.28 (dd, 1H, Jϭ8; 1 Hz, C8-H),
8.48 (dd, 1H, Jϭ8; 2 Hz, C4-H), 9.08 (dd, 1H, Jϭ5; 2 Hz, C2-H), 12.00 (br
s, 1H, D2O exch., NH). 13C-NMR (75 MHz, DMSO-d6) d: 119.4 (s, C-6a),
120.3 (d, C-11), 120.8 (d, C-5), 123.3 (s, C-7a), 123.4 (d, C-9), 124.2 (d, C-
6), 125.5 (d, C-3), 126.7 (d, C-8), 131.1 (s, C-4a), 134.1 (d, C-10), 137.7 (d,
C-4), 139.6 (s, C-12a), 140.0 (s, C-12b), 141.4 (s, C-11a), 150.1 (d, C-2),
177.4 (s, C-7). MS m/z: 246 (Mϩ). Anal. Calcd for C16H10N2O: C, 78.03; H,
4.09; N, 11.37. Found: C, 78.26; H, 4.35; N, 11.14.
2-(6-Methoxyquinolin-8-ylamino)benzoic Acid (12): 6-Methoxy-8-amino-
quinoline (8) (353 mg, 2.03 mmol) was reacted with 4 under conditions simi-
lar to those described for the preparation of 9 to afford 12 (246 mg, 41%) as
yellow crystals, mp: 203 °C. IR (KBr) cmϪ1: 3150—3000, 1620, 1280. UV
l
max (MeOH) nm (log e): 270 (4.30), 354 (3.76), 375 (3.97). 1H-NMR (300
MHz, DMSO-d6) d: 3.87 (s, 3H, O-CH3), 6.90 (d, 1H, Jϭ2 Hz, C7Ј-H), 6.97
(td, 1H, Jϭ8; 2 Hz, C5-H), 7.28 (d, 1H, Jϭ2 Hz, C5Ј-H), 7.53 (td, 1H, Jϭ8;
2 Hz, C4-H), 7.54 (dd, 1H, Jϭ8; 5 Hz, C3Ј-H), 7.77 (dd, 1H, Jϭ8; 2 Hz, C3-
H), 7.98 (dd, 1H, Jϭ8; 2 Hz, C6-H), 8.23 (dd, 1H, Jϭ8; 2 Hz, C4Ј-H), 8.72
(dd, 1H, Jϭ5; 2 Hz, C2Ј-H), 10.95 (br s, 1H, D2O exch., COOH), 13.15 (br
s, 1H, D2O exch., NH). 13C-NMR (75 MHz, DMSO-d6) d: 56.5 (q, O–CH3),
98.3 (d, C-7Ј), 104.1 (d, C-5Ј), 117.4 (2d, C-1, C-3), 120.5 (d, C-5), 123.7 (d,
C-3Ј), 130.9 (s, C-4Јa), 133.1 (d, C-4), 135.1 (d, C-6), 136.3 (d, C-4Ј), 137.0
(s, C-8Ј), 139.9 (s, C-8Јa), 145.0 (s, C-2), 147.0 (d, C-2Ј), 158.8 (s, C-6Ј),
170.1 (s, COOH). MS m/z: 294 (Mϩ), 279, 261, 249. Anal. Calcd for
C17H14N2O3: C, 69.38; H, 4.79; N, 9.52. Found: C, 69.15; H, 4.62; N, 9.20.
3-Nitro-N-(8-quinolyl)anthranilic Acid (13): Treatment of 7 (175 mg, 1.21
mmol) with 5 (246 mg, 1.22 mmol) under the conditions previously de-
scribed for the preparation of 9 afforded 13 (187 mg, 50%) as yellow crys-
tals, mp: 205—206. IR (KBr) cmϪ1: 3200—2900, 1680, 1620, 1560, 1325.
UV lmax (MeOH) nm (log e): 221 (3.90), 289 (3.73). mp: 205—206. 1H-
NMR (300 MHz, DMSO-d6) d: 6.74 (dd, 1H, Jϭ8; 2 Hz, C7Ј-H), 7.21 (t,
1H, Jϭ8, C5-H), 7.32 (t, 1H, Jϭ8 Hz, C6Ј-H), 7.43 (dd, 1H, Jϭ8; 2 Hz, C5Ј-
H), 7.57 (dd, 1H, Jϭ8; 5 Hz, C3Ј-H), 7.93 (dd, 1H, Jϭ8; 2 Hz, C6-H), 8.31
(dd, 1H, Jϭ8; 2 Hz, C4-H), 8.33 (dd, 1H, Jϭ8; 2 Hz, C4Ј-H), 8.87 (dd, 1H,
Jϭ5; 2 Hz, C2Ј-H), 12.55 (br s, 1H, D2O exch., COOH), 13.70 (br s, 1H,
D2O exch., NH). 13C-NMR (75 MHz, DMSO-d6) d: 109.8 (d, C-5Ј), 119.7
(d, C-5), 120.8 (d, C-7Ј), 123.1 (d, C-3Ј), 123.8 (s, C-1), 127.5 (d, C-4),
128.6 (d, C-6Ј), 129.9 (s, C-4Јa), 132.6 (s, C-8Јa), 137.2 (d, C-6), 137.7 (d,
C-4Ј), 138.5 (s, C-2), 140.1 (s, C-8Ј), 140.7 (s, C-3), 149.6 (d, C-2Ј), 171.0
(s, COOH). MS m/z: 309 (Mϩ), 264. Anal. Calcd for C16H11N3O4: C, 62.14;
H, 3.58; N, 13.59. Found: C, 62.55; H, 3.46; N, 13.42.
6-Methoxy-12H-benzo[b][1,10]phenanthrolin-7-one (17): A solution of
12 (50 mg, 0.17 mmol) and trifluoroacetic anhydride (1 ml, 7.14 mmol) in
anhydrous CH2Cl2 (10 ml) was stirred at room temperature for 3 d. After
evaporation of the solvent, the residue was washed with aqueous NaHCO3
(5%). The aqueous layer was further extracted with CH2Cl2 (2ϫ10 ml). The
organic layers were dried and evaporated to give 17 (30 mg, 64%) as yellow
prisms, mp: 242—243 °C. IR (KBr) cmϪ1: 3220, 2990, 1630. UV lmax
(MeOH) nm (log e): 263 (4.75), 284 (4.47), 349 (3.94). 1H-NMR (300 MHz,
DMSO-d6) d: 4.05 (s, 3H, O-CH3), 6.78 (s, 1H, C5-H), 7.33 (td, 1H, Jϭ8; 1
Hz, C9-H), 7.48 (dd, 1H, Jϭ8; 5 Hz, C3-H), 7.50 (dd, 1H, Jϭ8; 1 Hz, C11-
H), 7.67 (td, 1H, Jϭ8; 1 Hz, C10-H), 8.01 (dd, 1H, Jϭ8; 1 Hz, C8-H), 8.52
(dd, 1H, Jϭ8; 2 Hz, C4-H), 8.79 (dd, 1H, Jϭ5; 2 Hz, C2-H), 9.20 (br s, 1H,
D2O exch., NH). 13C-NMR (75 MHz, DMSO-d6) d: 56.0 (q, O–CH3), 95.9
(d, C-5), 111.5 (s, C-6a), 116.7 (d, C-11), 122.5 (d, C-9), 124.3 (d, C-3),
124.7 (s, C-7a), 127.2 (d, C-8), 130.5 (s, C-4a), 132.7 (d, C-10), 134.2 (s, C-
12a), 138.0 (s, C-12b), 139.9 (s, C-11a), 145.6 (d, C-2), 158.1 (s, C-6), 177.1
(s, C-7). MS m/z: 276 (Mϩ), 261. Anal. Calcd for C17H12N2O2: C, 73.90; H,
4.38; N, 10.14. Found: C, 73.55; H, 4.32; N, 10.25.
11-Nitro-12H-benzo[b][1,10]phenanthrolin-7-one (18): Cyclization of 13
(175 mg, 0.57 mmol) under conditions similar to those described for the
preparation of 14 afforded 18 (143 mg, 70%) as orange crystals, mp: 275—
276 °C. IR (KBr) cmϪ1: 3100—3000, 1620, 1520, 1330. UV lmax (MeOH)
1
nm (log e): 234 (3.80), 272 (3.56). H-NMR (300 MHz, DMSO-d6) d: 7.56
(t, 1H, Jϭ8 Hz, C9-H), 7.78 (d, 1H, Jϭ9 Hz, C5-H), 7.81 (dd, 1H, Jϭ8; 5
Hz, C3-H), 8.41 (dd, 1H, Jϭ8; 2 Hz, C4-H), 8.42 (d, 1H, Jϭ9 Hz, C6-H),
8.89 (dd, 1H, Jϭ8; 2 Hz, C10-H), 8.98 (dd, 1H, Jϭ8; 2 Hz, C8-H), 9.14 (dd,
1H, Jϭ5; 2 Hz, C2-H), 10.92 (br s, 1H, D2O exch., NH). 13C-NMR (75
MHz, DMSO-d6) d: 119.7 (s, C-6a), 122.4 (d, C-5), 123.2 (d, C-6), 123.4 (d,
C-3), 126.3 (d, C-9), 127.9 (s, C-7a), 131.4 (s, C-4a), 132.7 (d, C-8), 136.1
(d, C-10), 136.4 (d, C-11a), 138.1 (d, C-4), 138.2 (s, C-11), 140.7 ((s, C-
12a), (s, C-12b)), 151.5 (d, C-2), 176.6 (s, C-7). MS m/z: 291 (Mϩ). Anal.
Calcd for C16H9N3O3: C, 65.98; H, 3.11; N, 14.43. Found: C, 65.81; H, 2.94;
N, 14.32.
12H-Benzo[b][1,7]phenanthrolin-7-one (14): A solution of 9 (213 mg,
0.86 mmol) in concentrated sulfuric acid (5 ml) was heated at 100 °C for 5 h.
The cooled solution was poured into ice-water and basified with 30% aque-
ous NaOH. The solution was extracted with 2-butanone (3ϫ25 ml). The or-
ganic layers were dried over anhydrous Na2SO4, filtered, and evaporated
under reduced pressure. Recrystallization from ethanol gave 14 (143 mg,
67%) as a yellow crystalline product, mp: 293 °C. IR (KBr) cmϪ1: 3100—
3000, 1620. UV lmax (MeOH) nm (log e): 252 (4.02), 280 (3.75), 303
12-Methyl-12H-benzo[b][1,7]phenanthrolin-7-one (19): To a solution of
14 (127 mg, 0.52 mmol), benzyltriethylammonium chloride (330 mg, 1.45
mmol), and 30% aqueous NaOH (3 ml) in 2-butanone (3 ml) was added
methyl iodide (0.050 ml, 0.80 mmol). The mixture was stirred and refluxed
for 3 h. The cooled solution was diluted with a mixture of CH2Cl2/H2O (10
ml/5 ml). The aqueous solution was extracted with CH2Cl2. The organic
layer was dried over anhydrous Na2SO4, filtered, and evaporated under re-
duced pressure to afford 19 (54 mg, 40%) as yellow crystals, mp: 290 °C. IR
(KBr) cmϪ1: 3000, 2990, 1660, 1280, 750. UV lmax (MeOH) nm (log e):
254 (4.45), 290 (4.71), 332 (3.90), 350 (3.66), 376 (3.84). 1H-NMR (300
1
(3.25), 348 (3.24). H-NMR (300 MHz, DMSO-d6) d: 7.15 (td, 1H, Jϭ8; 1
Hz, C9-H), 7.41 (d, 1H, Jϭ9 Hz, C5-H), 7.67 (m, 2H, C2-H, C10-H), 7.83
(dd, 1H, Jϭ8; 1 Hz, C11-H), 8.37 (dd, 1H, Jϭ8; 1 Hz, C8-H), 8.40 (d, 1H,
Jϭ9 Hz, C6-H), 8.88 (dd, 1H, Jϭ5; 2 Hz, C3-H), 9.48 (dd, 1H, Jϭ8; 2 Hz,
C1-H), 12.50 (br s, 1H, D2O exch., NH). 13C-NMR (75 MHz, DMSO-d6) d:
117.6 (s, C-12b), 119.4 (d, C-11), 119.6 (s, C-6a), 122.3 (d, C-2), 122.9 (s,
C-7a), 123.5 (d, C-9), 123.6 (d, C-5), 126.7 (d, C-8), 127.3 (d, C-6), 132.7 (d,
C-1), 134.2 (d, C-10), 139.4 (s, C-12a), 141.5 (d, C-11a), 151.2 (s, C-4a),
153.4 (d, C-3), 177.0 (s, C-7). MS m/z: 246 (Mϩ). Anal. Calcd for

1080
Vol. 49, No. 9
grown in RPMI medium 1640 supplemented with 10% fetal calf serum, 2
mM L-glutamine, 100 U/ml penicillin, 100 mg/ml streptomycin and 10 mM
HEPES buffer (pH 7.4). The cytotoxicity was measured by microculture
tetrazolium assay essentially as described.25) Cells were exposed to graded
concentrations of the test drug (nine serial dilutions in triplicate) for 48 h.
Results are expressed as IC50 (mean, nϭ3), which is defined as the drug con-
centration inhibiting the absorbance by 50% with respect to that of untreated
cells.
MHz, DMSO-d6) d: 4.32 (s, 3H, N-CH3), 7.42 (td, 1H, Jϭ8; 1 Hz, C9-H),
7.50 (dd, 1H, Jϭ8; 5 Hz, C2-H), 7.66 (d, 1H, Jϭ9 Hz, C5-H), 7.82 (td, 1H,
Jϭ8; 2 Hz, C10-H), 7.91 (dd, 1H, Jϭ8; 2 Hz, C11-H), 8.54 (dd, 1H, Jϭ8; 2
Hz, C8-H), 8.67 (d, 1H, Jϭ9 Hz, C6-H), 8.69 (dd, 1H, Jϭ5; 2 Hz, C3-H),
9.02 (dd, 1H, Jϭ8; 2 Hz, C1-H). 13C-NMR (75 MHz, DMSO-d6) d: 44.6 (q,
N–CH3), 117.0 (d, C-11), 118.9 (d, C-2), 119.8 (d, C-12b), 121.3 (s, C-6a),
122.9 (d, C-9), 124.1 (s, C-7a), 124.5 (d, C-5), 126.7 (d, C-8), 127.1 (d, C-6),
133.6 (d, C-1), 135.0 (d, C-10), 143.8 (s, C-12a), 145.7 (s, C-11a), 151.5 (d,
C-3), 152.2 (s, C-4a), 177.4 (s, C-7). MS m/z: 260 (Mϩ), 245. Anal. Calcd
for C17H12N2O: C, 78.44; H, 4.65; N, 10.76. Found: C, 78.68; H, 4.36; N,
10.80.
12-Methyl-12H-benzo[b][1,10]phenanthrolin-7-one (20): Methylation of
16 (90 mg, 0.36 mmol) under conditions similar to those described for the
preparation of 19 afforded 20 (43 mg, 46%) as yellow crystals, mp: 281 °C.
IR (KBr) cmϪ1: 3100—3000, 1630, 1290, 750. UV lmax (MeOH) nm (log
e): 252 (4.55), 282 (4.65), 344 (4.04), 363 (3.97), 388 (3.99). 1H-NMR (300
MHz, DMSO-d6) d: 4.46 (s, 3H, N-CH3), 7.36 (td, 1H, Jϭ8; 1 Hz, C9-H),
7.51 (dd, 1H, Jϭ8; 5 Hz, C3-H), 7.65 (d, 1H, Jϭ9 Hz, C5-H), 7.73 (td, 1H,
Jϭ8; 1 Hz, C10-H), 7.76 (dd, 1H, Jϭ8; 1 Hz, C11-H), 8.18 (dd, 1H, Jϭ8; 1
Hz, C8-H), 8.53 (d, 1H, Jϭ9 Hz, C6-H), 8.55 (dd, 1H, Jϭ8; 2 Hz, C4-H),
8.93 (dd, 1H, Jϭ5; 2 Hz, C2-H). 13C-NMR (75 MHz, DMSO-d6) d: 43.6 (q,
N–CH3), 117.0 (d, C-11), 121.3 (d, C-5), 122.2 (d, C-9), 122.5 (d, C-6),
122.6 (d, C-6a), 122.8 (d, C-7a), 123.8 (d, C-3), 126.7 (d, C-8), 132.2 (s, C-
4a), 133.3 (d, C-10), 136.1 (d, C-4), 141.5 (s, C-12a), 142.3 (s, C-12b),
145.1 (s, C-11a), 146.6 (d, C-2), 177.6 (s, C-7). MS m/z: 260 (Mϩ), 245.
Anal. Calcd for C17H12N2O: C, 78.44; H, 4.65; N, 10.76. Found: C, 78.32; H,
4.71; N, 10.51.
Acknowledgments Financial support from the Comité Régional de
Haute-Normandie de la Ligue Nationale contre le Cancer is gratefully ac-
knowledged.
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6-Methoxy-12-methyl-12H-benzo[b][1,10]phenanthrolin-7-one (21): Methyl
iodide (0.4 ml, 6.38 mmol) was added to a solution of 17 (55 mg, 0.2 mmol)
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(MeOH) nm (log e): 266 (4.41), 283 (4.28), 385 (3.79). 1H-NMR (300 MHz,
DMSO-d6) e: 4.13 (s, 3H, N-CH3), 4.37 (s, 3H, O–CH3), 6.85 (s, 1H, C5-H),
7.35 (td, 1H, Jϭ8; 1 Hz, C9-H), 7.57 (dd, 1H, Jϭ8; 5 Hz, C3-H), 7.68 (dd,
1H, Jϭ8; 1 Hz, C11-H), 7.74 (td, 1H, Jϭ8; 1 Hz, C10-H), 8.05 (dd, 1H, Jϭ
8; 1 Hz, C8-H), 8.58 (dd, 1H, Jϭ8; 2 Hz, C4-H), 8.80 (dd, 1H, Jϭ5; 2 Hz,
C2-H). 13C-NMR (75 MHz, DMSO-d6) d: 43.2 (q, N–CH3), 56.7 (q,
O–CH3), 96.7 (d, C-5), 113.2 (s, C-6a), 114.5 (d, C-11), 122.1 (d, C-9),
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N, 9.72.
11-Amino-12H-benzo[b][1,10]phenanthrolin-7-one (22): To a solution of
18 (50 mg, 0.17 mmol) in DMF (15 ml), was added 10% Pd/C (20 mg). The
mixture was stirred at room temperature for 2 h under H2 (1 atm.), filtered
and evaporated under reduced pressure. Column chromatography of the
residue on silica gel (solvent: CH2Cl2/MeOH : 97/3 : v/v) gave 22 (40 mg,
90%) as yellow crystals, mp: 259—260 °C. IR (KBr) cmϪ1: 3150, 2980,
1590, 1430, 1595. UV lmax (MeOH) nm (log e): 223 (3.56), 245 (3.19). 1H-
NMR (300 MHz, DMSO-d6) d: 5.85 (s, 2H, NH2) 7.15 (dd, 1H, Jϭ8; 2 Hz,
C10-H), 7.17 (t, 1H, Jϭ8 Hz, C9-H), 7.66 (dd, 1H, Jϭ8; 2 Hz, C8-H), 7.68
(d, 1H, Jϭ9 Hz, C5-H), 7.84 (dd, 1H, Jϭ8; 5 Hz, C3-H), 8.26 (d, 1H, Jϭ9
Hz, C6-H), 8.52 (dd, 1H, Jϭ8; 2 Hz, C4-H), 9.10 (dd, 1H, Jϭ5; 2 Hz, C2-
H), 10.80 (br s, 1H, D2O exch., NH). 13C-NMR (75 MHz, DMSO-d6) d:
115.3 (d, C-9), 118.6 (s, C-6a), 118.8 (d, C-5), 120.6 (d, C-6), 123.7 (d, C-3),
124.0 (d, C-10), 125.3 (d, C-8), 130.5 (s, C-7a), 130.6 (s, C-4a), 137.6 (d, C-
4), 138.1 (s, C-11a), 138.8 ((s, C-11), (s, C-12a)), 139.5 (s, C-12b), 150.0 (d,
C-2), 177.4 (s, C-7). MS m/z: 261 (Mϩ). Anal. Calcd for C16H11N3O: C,
73.55; H, 4.24; N, 16.08. Found: C, 73.69; H, 4.33; N, 15.97.
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Biological Pharmacology Cytotoxicity: Murine leukemia L1210 cells
from the American Type Culture Collection (Rockville Pike, MD) were