Synthesis and structure-activity relationships of 3-aminobenzophenones as antimitotic agents

Article abstract of DOI:10.1021/jm0305974

A new series of 3-aminobenzophenone compounds as potent inhibitors of tubulin polymerization was discovered based on the mimic of the aminocombretastatin molecular skeleton. Lead compounds 5 and 11, with alkoxy groups at the C-4 position of B-ring, were p

Full text of DOI:10.1021/jm0305974

J . Med. Chem. 2004, 47, 2897-2905
2897
Syn th esis a n d Str u ctu r e-Activity Rela tion sh ip s of 3-Am in oben zop h en on es a s
An tim itotic Agen ts
J ing-Ping Liou,†,§ J ang-Yang Chang,‡,§ Chun-Wei Chang, Chi-Yen Chang,‡ Neeraj Mahindroo,†
Fu-Ming Kuo,† and Hsing-Pang Hsieh*,†
Division of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Taipei, Taiwan, Republic of
China and Division of Cancer Research, National Health Research Institutes, Taipei, Taiwan, Republic of China
Received November 26, 2003
A new series of 3-aminobenzophenone compounds as potent inhibitors of tubulin polymerization
was discovered based on the mimic of the aminocombretastatin molecular skeleton. Lead
compounds 5 and 11, with alkoxy groups at the C-4 position of B-ring, were potent cytotoxic
agents and inhibitors of tubulin polymerization through the binding to the colchicine-binding
site of tubulin. The corresponding antitubulin activities of 5 and 11 were similar to or greater
than combretastatin A-4 and AVE-8063. Replacement of the methoxy group with a chloro group
in the B ring of aminobenzopheneones (3, 8, and 9) caused drastic decrease in cytotoxic and
antitubulin activity except in compounds 4 and 10, which could result from a unique alignment
between chloro and amino groups located at the para position to each other. SAR information
revealed that introduction of an amino group at the C-3 position in B ring of benzophenones,
in addition to a methoxy group at the C-4 position, plays an important role for maximal
cytotoxicity.
Ch a r t 1
In tr od u ction
Microtubules are dynamic structures that play a
crucial role in cellular division and are recognized as
an important target for anticancer therapy.1 A number
of naturally occurring compounds, such as paclitaxel,
epothilone A, vinblastine, combretastatin A-4, dolastatin
10, and colchicines, all exhibit their anticancer proper-
ties by interfering with the dynamics of tubulin poly-
merization and depolymerization, resulting in mitotic
arrest.2 Combretastatin A-4 (CA-4), a natural product
isolated by Pettit and co-workers in 1982 from the South
African bush willow tree Combretum caffrum, strongly
inhibits the polymerization of tubulin by binding to the
colchicine site.3 CA-4 exerts potent cytotoxicity against
a variety of human cancer cells including multidrug
resistant (MDR) cancer cell lines.4 Moreover, CA-4 has
been demonstrated to elicit selective and irreversible
shutdown of blood flow to neoplastic cells while leaving
the blood supply to healthy cells intact.5
Despite its very potent cytotoxic and antitubulin
activities in vitro, CA-4 as an antimitotic agent showed
poor antitumor effects in in vivo models due to, at least
in part, its limited water solubility.1 On the other hand,
CA-4P, a disodium phosphate prodrug, displayed potent
antivascular and antitumor effects in a wide range of
preclinical tumor models5 and is currently in phase II
clinical trials. Due to the dual antivascular/antitumor
features of CA-4P, a number of diverse ligands designed
to mimic CA-4 have been synthesized6 and are broadly
categorized as CA-4 derivatives and CA-4 analogues.
The CA-4 derivatives6,7 (Chart 1), for example, CA-4P,7a
CA-1P7b (Oxi-4503), AC-7700,7c not only demonstrate
substantial antivascular activity in tumor blood flow,
distinguishing it from the normal tissues,8,9 but also
show antitumor effects in some tumor models,10 alone
or in combination with the other chemotherapeutic
drugs, such as cisplatin, carboplatin, 5-FU, and doxo-
rubicin, or radiotherapeutic treatment.11 The CA-4
analogues12 (Chart 2), containing a variety of hetero-
* Corresponding author. Division of Biotechnology and Pharmaceu-
tical Research, National Health Research Institutes, 9F, 161, Sec. 6,
Min-Chiuan East Road, Taipei 114, Taiwan, Republic of China.
Phone: 886-2-2653-4401 ext. 6577; fax: 886-2-2792-9703; e-mail:
hphsieh@nhri.org.tw.
† Medicinal Synthetic Laboratory, Division of Biotechnology and
Pharmaceutical Research.
‡ Division of Cancer Research.
§ These authors contributed equally.
10.1021/jm0305974 CCC: $27.50 © 2004 American Chemical Society
Published on Web 04/20/2004

2898 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 11
Liou et al.
Ch a r t 2
cyclic moieties, such as oxadiazolines, imidazoles, ox-
azolines, benzothiophenes, benzofurans, indoles, thia-
zoles and tetrazoles, not only display efficient inhibition
of tubulin polymerization but also exert potent cellular
growth inhibition in different cancer lines including
MDR cancer cells. It is worthy to note that some of CA-4
analogues, such as imidazole-based CA-412b and 2-aroyl-
5-methoxyindoles,13 exhibited oral availability leading
to solid tumor regression in in vivo tumor models.
Ohsumi and co-workers reported a series of ami-
nocombretastatins in 1998.7c Among these derivatives,
AVE-8063, with an amino group replacing the hydroxyl
group at the C-3 position of CA-4, showed potent
antitubulin activity and cytotoxicity against murine
colon 26 adenocarcinoma cells.9c Its serine-prodrug AVE-
8062 (formally AC-7700) was found to possess more
potent antivascular and antitumor activities in com-
parison with CA-4P.9c,14 Additionally, Hori and co-
workers have demonstrated that AVE-8062 exerts
antivascular and antitumor effects both in rapidly
proliferating transplanted tumors and in relatively
slowly proliferating primary tumors induced by chemi-
cal carcinogens.14 Since early 2002, AVE-8062 is un-
dergoing phase I clinical trials in the Europe and the
US.15 Phenstatin, another CA-4 derivative designed
from CA-4 skeleton by replacing the olefin group with
a carbonyl group while retaining 3-hydroxy-4-methoxy-
benzene as B-ring, was discovered as a potent antitu-
bulin agent by Pettit’s lab.7d
We have been actively engaged in searching for novel
antimitotic benzophenone-type molecules that target
tubulin16 and have revealed that the presence of an
amino group at the C-2 position of the benzophenone
ring, for example 2-aminobenzophenones 1 and 2,
increased cytotoxic activity by 100-fold compared to the
corresponding compounds with a hydroxyl group at the
C-2 position.16a In continuation of our work in this field,
we designed a series of 3-aminobenzophenone com-
pounds based on the structures of AVE-8063 and
phenstatin (Chart 3) and report herein their synthesis
and cytotoxic activities against a variety of human
cancer cells including an MDR-positive cancer cell line,
antitubulin activity, and the ability of colchicine com-
petition-binding.
Resu lts a n d Discu ssion
Ch em istr y. The general method for the synthesis of
3-aminobenzophenones is shown in Scheme 1. The
preparation involved a straightforward reaction se-
quence with high yields (overall 54-70% in three
steps): (1) Grignard reaction of (3,4,5-trimethoxyphen-
yl)magnesium bromide with various substituted 3-ni-
trobenzaldehydes yielded the corresponding secondary
benzyl alcohols A; (2) pyridinium dichromate (PDC)
oxidation of A to the corresponding 3-nitrobenzophen-
ones B; and (3) reduction of the nitro group in B with
Fe/AcOH to afford the desired substituted 3-aminoben-
zophenones C.
Most of the methoxy- or chloro-substituted 3-ni-
trobenzaldehydes were commercially available except
for the 3-chloro-5-nitrobenzaldehyde 18 and 3-methoxy-
5-nitrobenzaldehyde 22, which were synthesized as
shown in Schemes 2 and 3, respectively. Compound 18
was obtained via a three-step synthesis starting from
commercially available 3,5-dinitrobenzyl alcohol (Scheme
2). Selective reduction of 3,5-dinitrobenzyl alcohol with
ammonium sulfite in methanol afforded the correspond-
ing 3-amino-5-nitrobenzyl alcohol which was converted
to 3-chloro-5-nitrobenzyl alcohol by Sandmeyer reaction
in the presence of NaNO2 and CuCl2. Finally, PDC
oxidation of which then gave the desired benzaldehyde
18.17 Another key building block 3-methoxy-5-nitroben-
zaldehyde 22 was obtained from 3,5-dinitrobenzoic acid
via sequential reactions: nucleophilic addition by lithium
methoxide in hexamethylphosphoric triamide18 followed
by BH3 reduction and PDC oxidation as shown in
Scheme 3.
To elongate the chain length of the alkoxy group at
the C-4 position, a series of 4-alkoxy-3-nitrobenzalde-
hydes 24-26 were synthesized (Scheme 4) by base-
promoted O-alkylation of 4-hydroxy-3-nitrobenzalde-
hyde with ethyl, propyl, and isopropyl iodide in the

3-Aminobenzophenones as Antimitotic Agents
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 11 2899
Ch a r t 3
Sch em e 1a
a
Reagents and conditions: (a) THF, 0-25 °C; (b) PDC, CH2Cl2, 25 °C; (c) Fe, AcOH, EtOH, reflux
presence of K2CO3 in anhydrous CH3CN in 75-82%
yield. The reduction of the benzylic carbonyl group of
compound 5 to the methylene with an efficient protocol
utilizing NaBH4/TFA at room temperature afforded 14
in 62% yield (Scheme 5).
Biologica l Eva lu a tion . (A) In Vitr o Cell Gr ow th
In h ibitor y Activity. The synthesized aminobenzophen-
ones 1-14 were evaluated for their cytotoxic activities
against three types of human cancer cell lines, oral
epidermoid carcinoma KB cells, colorectal carcinoma
HT29 cells, and stomach carcinoma TSGH cells, as well
as one type of MDR-positive cell line: KB-VIN10 cells,
overexpressed P-gp 170/MDR (Table 1).
We first evaluated the cytotoxic effect of an amino
substitution at the C-3 position. Newly synthesized
phenstatin analogue 5, with an amino group at the C-3
position on the B-ring, exhibited similar or greater
cytotoxic activity than phenstatin. Changing the posi-

2900 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 11
Liou et al.
Sch em e 2a
a
Reagents and conditions: (a) (NH4)2S, MeOH, reflux; (b) NaNO2, HCl, then CuCl2, 60 °C; (c) MnO2, CH2Cl2, 25 °C; (d)
3,4,5-trimethoxyphenylmagnesium bromide, THF, 0-25 °C; (e) PDC, CH2Cl2, 25 °C; (f) Fe, AcOH, EtOH, reflux
Sch em e 3a
a
Reagents and conditions: (a)LiOCH2, HMPA, 25 °C; (b) BH3, THF, 0-25 °C; (c) PDC, CH2Cl2, 25 °C; (d) 3,4,5-trimethoxyphenyl-
magnesium bromide, THF, 0-25 °C; (e) PDC, CH2Cl2, 25 °C; (f) Fe, AcOH, EtOH, reflux
Sch em e 4a
a
Reagents and conditions: (a) K2CO3, Etl, PrI, or i-PrI, CH3CN, reflux; (b) 3,4,5-trimethoxyphenylmagnesium bromide, THF, 0-25
°C; (c) PDC, CH2Cl2, 25 °C; (d) Fe, AcOH, EtOH, reflux
Sch em e 5a
a
Reagents and conditions: (a) 3,4,5-trimethoxyphenylmagnesium bromide, THF, 0-25 °C; (c) PDC, CH2Cl2, 25 °C; (d) Fe, AcOH, EtOH,
reflux. (d) NaBH4, TFA, CH2Cl2, 25 °C
tion of the methoxy group on the B-ring from C-4 to C-5
and C-6, as in compounds 6 and 7, respectively, de-
creased cytotoxicity by 5- to 10-fold as compared to 5.
Similar tendencies were also observed in the 2-ami-
nobenzophenone series (1 vs phenstatin and 1 vs 2).
Replacement of a methoxy group (5, 6, and 7) with a
chloro group (8, 9, and 10) was then examined. It is
interesting to note that compound 10 with a chloro
group at the C-6 position maintains substantial potency
as compared to 5, while substitution at the C-4 and C-5
positions (8 and 9) resulted in significant decrease in
cytotoxicity. A comparison of substituent effect by chloro
and methoxy groups in 2-aminobenzophenones and
3-aminobenzophenones (1 vs 3, 2 vs 4, 5 vs 8, 6 vs 9,
and 7 vs 10) indicates that chloro substitution in
2-aminobenzophenones was more tolerated than in
3-aminobenzophenones. A surprising observation was
that a chloro group located at the para position to an
amino group (4 and 10) retained potency in cytotoxicity
assay, although it was previously reported that replace-
ment of a methoxy group with a chloro group resulted
in a decrease of potency.16b Moreover, chloro substitution
at the C-5 position of 2-aminobenzophenones (4 vs 2)
as well as at the C-6 position of 3-aminobenzophenones
(10 vs 7) showed maximal effects. Replacing a carbonyl
group (5) with a methylene group (14) resulted in
complete loss of activity indicating that the carbonyl
moiety between A-ring and B-ring is critical for activity.
To understand the steric effect of alkoxy substituents
at the C-4 position, we synthesized ethoxy, propyloxy,
and isopropyloxy compounds 11, 12, and 13, respec-
tively. Although compound 11 retained substantial
cytotoxicity in comparison with 5 and phenstatin,
further increase in the bulkiness of the alkoxy moiety
resulted in drastic decrease in potency. This revealed
that steric effect of the substitutions at the crucial C-4
position of B-ring in aminobenzophenones significantly
influences their cytotoxic activities. This is consistent

3-Aminobenzophenones as Antimitotic Agents
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 11 2901
Ta ble 1. IC50 Values (nM ( SDa) of Aminobenzophenone
Analogues (1-14), Phenstatin, AVE-8063, and CA-4
Ta ble 2. Inhibition of Tubulin Polymerization by
Aminobenzophenone Analogues (1-14), Phenstatin, AVE-8063,
and CA-4
cell type (IC50 nM ( SD)a
inhibition of tubulin polymerization
compd
KB
KB-Vin10
HT29
TSGH
26 ( 3
100 ( 12
800 ( 63
185 ( 29
33 ( 4
compound
IC50 (µM ( SD)a
17j
27j
3
32 ( 17
127 ( 35
710 ( 91
195 ( 18
32 ( 2
590 ( 31
306 ( 45
800 ( 88
24 ( 8
42 ( 7
1
2
3
4
5
6
7
8
9
10
11
12
13
14
0.4 ( 0.1
1.0 ( 0.2
2.7 ( 0.5
0.1 ( 0.1
0.3 ( 0.2
2.6 ( 0.6
2.9 ( 0.7
11 ( 2
352 ( 87
800 ( 73
162 ( 28
31 ( 6
148 ( 26
1000 ( 33
218 ( 42
33 ( 9
47o
5
6
7
8
9
10
11
12
13
14
307 ( 53
324 ( 26
163 ( 14
400 ( 78
157 ( 33
497 ( 67
3800 ( 278 4000 ( 396 4000 ( 729
1400 ( 128 2900 ( 35
180 ( 45
59 ( 11
3800 ( 260 8600 ( 460 9000 ( 850 4800 ( 244
900 ( 84
>10000
1900 ( 77
163 ( 29
45 ( 7
1500 ( 25
157 ( 31
42 ( 16
125 ( 18
40 ( 9
17 ( 3
0.6 ( 0.2
0.7 ( 0.3
42 ( 8
800 ( 33
>10000
30 ( 4
7.5 ( 2
2.4 ( 5
1300 ( 169 900 ( 47
>10000
560 ( 28
7.9 ( 8
>10000
170 ( 5
7.7 ( 9
45 ( 12
6.4 ( 0.8
> 50
Phenstatin7j 30 ( 6
AVE-80637c 8.2 ( 1
Phenstatin
AVE-8063
CA-4
0.4 ( 0.2
0.3 ( 0.2
1.0 ( 0.3
CA-47j
2.1 ( 3
260 ( 6
a
SD: standard deviation, all experiments were independently
performed at least three times.
a
SD: standard deviation, all experiments were independently
performed at least three times.
with observations in other literature reports on CA-4
derivatives19 which suggest that the tolerance of alkoxy
substitution in CA-4 family is limited up to ethoxy
substitution.
A comparison between cytotoxic activities of 5, phen-
statin, AVE-8063, and CA-4 reveals that the introduc-
tion of an amino group at the C-3 position is beneficial
for potency especially against HT29 and TSGH cells.
This result is in agreement with our observation in the
2-aminobenzophenone series (1 vs phenstatin). Hence,
it may be concluded that an amino group located at the
B-ring, either at the C-2 or C-3 position, seems to play
an integral role in the inhibition of cellular growth.
Moreover, all synthesized 3-aminobenzophenones 6-13
overcome MDR-positive resistant cells (KB-Vin10),
indicating 3-aminobenzophenones are not substrates for
efflux pump.
(B) In h ibition of Tu bu lin P olym er iza tion . As CA-
4, phenstatin, and AVE-8063 have been well docu-
mented to show interactions with tubulin, 14 synthe-
sized aminobenzophenones were evaluated for their
antitubulin polymerization activities as shown in Table
2. The results demonstrated that the cytotoxicities of
the aminobenzophenones correlated well with the in-
hibitory ability of tubulin polymerization. For instance,
six compounds 1, 2, 4, 5, 10, and 11 exhibited strong
antitubulin activities (IC50 e 1.0 µM) and exhibited
higher cytotoxic activities than the other eight ami-
nobenzophenones. It is interesting to note that two
chloro-containing compounds 4 and 10 with a chloro
group located at the para position to an amino group
possess a unique alignment which imparts them with
10-fold more potency than the other two chloro-contain-
ing compounds 8 and 9 in the antitubulin activity assay.
Another unexpected observation is that compound 4
(IC50 ) 0.1 µM) displays 3- to 10-fold more potent
antitubulin activity than AVE-8063 and CA-4 (0.3 µM
and 1.0 µM) but shows only moderate cytotoxic activity.
Taking into account the influence of methoxy substi-
tutent, we found that both 4′-methoxy 5 (IC50 ) 0.3 µM)
and 4′-ethoxy 11 (IC50 ) 0.7 µM) showed similar or
greater antitubulin activities than CA-4, phenstatin,
and AVE-8063. Shifting methoxy substitution to differ-
ent positions (5 vs 6 and 7) or changing to a more bulky
F igu r e 1. Inhibition of colchicine binding to MAP-rich tubulin
for compounds 1, 5, 7, 10, and AVE-8063 at 1, 5, 10, and 50
µM.
alkoxy substitution (5 vs 11 and 12) led to a decrease
in activity. The order of inhibition of tubulin polymer-
ization by aminobenzophenones with methoxy groups
in the B-ring is 5 = 1 > 2 > 6 = 7, indicating that a
methoxy substitutent at the C-4 position plays an
important role to impart both strong antitubulin and
cytotoxic activities while the position of amino group is
more flexible and can either be at the C-2 or C-3
position.
(C) In h ibition of Colch icin e Bin d in g Activity. To
examine the binding affinity of aminobenzophenones to
the colchicine-binding domain, we selected the com-
pounds 1, 5, 7, and 10 to determine their ability to
compete for colchicine-binding sites. It was observed
that 1 and 5 showed strong inhibition of colchicine-
binding which was correlated with their strong antitu-
bulin and cytotoxic activities whereas compound 7 was
less potent in tubulin polymerization due to weak
binding affinity to colchicine-binding sites (Figure 1).
Additionally, it is suggested that 3-amino-6-chloro-
substituted compound 10 exhibited relatively potent
cytotoxicity resulting from effective inhibition of tubulin
polymerization and colchicine-binding activity.

2902 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 11
Liou et al.
6 mmol) in portions. After 16 h, the reaction mixture was
filtered through a pad of Celite. The filtrate was concentrated
in vacuo, and the residue was purified by flash chromatogra-
phy to obtain desired substituted 3-nitrobenzophenone.
P r oced u r e C. A stirred suspension of substituted 3-ni-
trobenzophenone (1 mmol) and iron powder (0.50 g) in ethanol
(5 mL), acetic acid (5 mL), water (2 mL), and 37% hydrochloric
acid (1 drop) was vigorously stirred and refluxed. After 1 h,
the reaction mixture was cooled and filtered through Celite.
The filtrate was diluted with sat. NaHCO3 and extracted by
CH2Cl2 (10 mL × 3). The combined organic layers were dried
over MgSO4 and evaporated. The residue was further purified
by flash chromatography to yield desired substituted 3-ami-
nobenzophenone.
Con clu sion s
In our newly synthesized 3-aminobenzophenone se-
ries, lead compounds 5 and 11, with alkoxy groups at
the C-4 position of B-ring, are potent cytotoxic agents
and inhibitors of tubulin polymerization through the
binding with the colchicines-binding site of tubulin. The
compounds 5 and 11 exhibit cytotoxic activity with IC50
range from 31 to 59 nM in a variety of human cell lines
from different organs. They also show similar or greater
antitubulin activities than CA-4, phenstatin, and AVE-
8063. In addition, the methoxy group should preferably
be located at the C-4 position for better activity rather
than at the C-5 or C-6 position and the tolerance of
alkoxy substitution at the C-4 position could be extended
up to an ethoxy group. Furthermore, replacement of the
methoxy group with a chloride at the C-4 and C-5
positions (8 and 9) results in significant decrease in
cytotoxicity. Notably, with a chloro moiety located at the
para position to an amino group, compounds 4 and 10
possess an unique alignment to produce both strong
cytotoxic and antitubulin activities. The complete loss
of activity in 14 indicates a carbonyl linker between
A-ring and B-ring is critical for activity. Examination
of the SAR in aminobenzophenone analogues revealed
that introduction of an amino group in the B ring plays
an integral role for maximal cytotoxicity though its
position appears to be more flexible as compared to
methoxy group and can either be at the C-2 or C-3
position.
(b) (2-Am in o-4-ch lor op h en yl)(3,4,5-tr im eth oxyp h en yl)-
m eth a n on e (3). The title compound was obtained in 70%
overall yield from 3,4,5-trimethoxyphenyl bromide and 4-chloro-
2-nitrobenaldehyde in three steps following procedures A-C;
1
mp 129-130 °C. H NMR (300 MHz, CDCl3): δ 3.86 (s, 6H, 2
× OCH3), 3.91 (s, 3H, OCH3), 6.14 (br, 2H), 6.56 (dd, J ) 1.8,
8.4 Hz, 1H), 6.73 (d, J ) 1.8 Hz, 1H), 6.85 (s, 2H), 7.42 (d, J
) 8.4 Hz, 1H). 13C NMR (CDCl3): δ 56.2, 60.8, 106.4, 115.6,
116.0, 116.3, 134.5, 135.1, 139.8, 140.5, 151.3, 152.4, 196.7.
MS (EI) m/z: 321 (M+, 100%), 323 (M + 2, 34%). HRMS (EI)
for C16H16ClNO4 (M+): calcd, 321.0774; found, 321.0771. Anal.
(C16H16ClNO4) C, H, N.
(c) (3-Am in o-4-m eth oxyp h en yl)(3,4,5-tr im eth oxyp h en -
yl)m eth a n on e (5). The title compound was obtained in 66%
overall yield from 3,4,5-trimethoxyphenyl bromide and 4-meth-
oxy-3-nitrobenaldehyde following procedures A-C; mp 146.5
°C. 1H NMR (300 MHz, CDCl3): δ 3.88 (s, 6H, 2 × OCH3),
3.93 (s, 3H, OCH3), 3.94 (s, 3H, OCH3), 6.82 (d, J ) 8.4 Hz,
2H), 7.02 (s, 1H), 7.21 (dd, J ) 8.1, 2.1 Hz, 1H), 7.26 (s, 1H).
13C NMR (CDCl3): δ 55.7, 56.3, 60.9, 107.2, 108.8, 115.6, 122.1,
130.3, 133.3, 135.9, 141.1, 150.5, 152.4, 194.7. MS (EI) m/z:
317 (M+, 100%), 274 (43%). HRMS (EI) for C17H19NO5 (M+):
calcd, 317.1271; found, 317.1267. Anal. (C17H19NO5) C, H, N.
(d ) (3-Am in o-5-m eth oxyp h en yl)(3,4,5-tr im eth oxyp h en -
yl)m eth a n on e (6). The title compound was obtained in 61%
overall yield from 3,4,5-trimethoxyphenyl bromide and 3-meth-
oxy-5-nitrobenaldehyde 16 following procedures A-C; mp 165
Exp er im en ta l Section
(A) Gen er a l Meth od s. Melting points were determined on
a Yanaco (MP-500D) melting point apparatus and are uncor-
rected. Nuclear magnetic resonance (1H NMR and 13C NMR)
spectra were obtained with a Varian Mercury-300 spectrom-
eter operating at 300 MHz and at 75 MHz, respectively, with
chemical shift in parts per million (ppm, δ) downfield from
TMS as an internal standard. High-resolution mass spectra
(HRMS) were measured with a Finnigan (MAT-95XL) electron
impact (EI) mass spectrometer. Elemental analyses were
performed on a Heraeus CHN-O Rapid microanalyzer. Flash
column chromatography was done using silica gel (Merck
Kieselgel 60, No. 9385, 230-400 mesh ASTM). Monitoring of
reaction by TLC used Merck 60 F254 silica gel glass backed
plates (5 × 10 cm); zones were detected visually under
ultraviolet irradiation (254 nm) or by spraying with phospho-
molybdic acid reagent (Aldrich) followed by heating at 80 °C.
All solvents were dried according to standard procedures. All
reagents were used as purchased without further treatment
unless otherwise stated. All reactions were carried out under
an atmosphere of dry nitrogen.
(B) Ch em istr y. (a ) Gen er a l P r oced u r e for th e P r ep a -
r a tion of Su bstitu ted 3-Am in oben zop h en on e Der iva -
tives (3, 5-13). P r oced u r e A. 3,4,5-Trimethoxyphenylmag-
nesium bromide (1.0 M) prepared from 3,4,5-trimethoxyphenyl
bromide16a (8.08 mmol) and magnesium turnings (8.9 mmol)
in anhydrous tetrahydrofuran (8-9 mL) was added slowly to
the corresponding substituted 3-nitrobenzoaldehydes in tet-
rahydrofuran (10 mL) at 0 °C. The reaction mixture was
warmed to room temperature, and stirring was continued for
another 30 min. A saturated NH4Cl solution (10 mL) was
slowly added to hydrolyze the adduct at 0 °C, and the mixture
was extracted with EtOAc (10 mL × 3). The combined organic
layers were dried over MgSO4, filtered, and concentrated in
vacuo. The residue was purified by flash column to furnish
desired benzyl alcohol.
1
°C. H NMR (300 MHz, CDCl3): δ 3.80 (s, 3H, OCH3), 3.88 (s,
6H, 2 × OCH3), 3.94 (s, 3H, OCH3), 6.43 (t, J ) 2.25 Hz, 1H),
6.68-6.69 (m, 2H), 7.08 (s, 2H). 13C NMR (CDCl3): δ 55.4, 56.3,
60.9, 104.6, 104.9, 107.5, 109.2, 132.4, 139.5, 141.6, 147.3,
152.4, 160.1, 195.2. MS (EI) m/z: 317 (M+, 100%). HRMS (EI)
for C17H19NO5 (M+): calcd, 317.1265; found, 317.1264. Anal.
(C17H19NO5) C, H, N.
(e) (3-Am in o-6-m eth oxyp h en yl)(3,4,5-tr im eth oxyp h en -
yl)m eth a n on e (7). The title compound was obtained in 59%
overall yield from 3,4,5-trimethoxyphenyl bromide and 2-meth-
oxy-5-nitrobenaldehyde following procedures A-C. 1H NMR
(300 MHz, CDCl3): δ 3.67 (s, 3H, OCH3), 3.83 (s, 6H, 2 ×
OCH3), 3.92 (s, 3H, OCH3), 6.68 (t, J ) 2.4 Hz, 1H), 6.79 (dd,
J ) 2.1, 8.7 Hz, 1H), 6.83 (d, J ) 8.7 Hz, 1H), 7.10 (s, 2H). 13
C
NMR (CDCl3): δ 56.1, 56.3, 60.8, 107.3, 113.2, 115.9, 118.1,
129.4, 132.6, 139.9, 142.4, 150.0, 152.7, 195.2. MS (EI) m/z:
317 (M+, 100%). Anal.(C17H19NO5) C, H, N.
(f) (3-Am in o-4-ch lor op h en yl)(3,4,5-tr im eth oxyp h en yl)-
m eth a n on e (8). The title compound was obtained in 69%
overall yield from 3,4,5-trimethoxyphenyl bromide and 4-chloro-
3-nitrobenaldehyde following procedures A-C; mp 125-126
°C. 1H NMR (300 MHz, CDCl3): δ 3.87 (s, 6H, 2 × OCH3),
3.93 (s, 3H, OCH3), 7.02 (s, 2H), 7.04 (dd, J ) 8.1, 2.1 Hz, 1H),
7.20 (d, J ) 1.8 Hz, 1H), 7.32 (d, J ) 8.1 Hz, 1H). 13C NMR
(CDCl3): δ 56.6, 60.9, 107.4, 116.3, 120.2, 123.0, 128.8, 132.2,
137.0, 141.8, 142.7, 152.5, 194.5. MS (EI) m/z: 321 (M+, 100%),
323 (M + 2, 41%). HRMS (EI) for C16H16ClNO4 (M+): calcd,
321.0764; found, 321.0766. Anal. (C16H16ClNO4) C, H, N.
(g) (3-Am in o-4-ch lor op h en yl)(3,4,5-tr im eth oxyp h en yl)-
m eth a n on e (9). The title compound was obtained in 58%
overall yield from 3,4,5-trimethoxyphenyl bromide and 3-chloro-
5-nitrobenaldehyde 15 following procedures A-C; mp 120-
121 °C. 1H NMR (300 MHz, CDCl3): δ 3.87 (s, 6H, 2 × OCH3),
P r oced u r e B. To a stirred solution of benhydrol (4 mmol)
and 4 Å molecular sieves (0.60 g) in dichloromethane (20 mL)
at room temperature was added pyridinium dichromate (PDC,

3-Aminobenzophenones as Antimitotic Agents
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 11 2903
3.93 (s, 3H, OCH3), 4.23 (br, 2H), 7.03 (s, 2H), 7.05 (d, J )
room temperature for 16 h. The reaction was quenched with
sat. NaHCO3, extracted with CH2Cl2, and then evaporated the
organic layer to dryness in vacuo. The residue in the presence
of 4 Å molecular sieve (0.38 g) was directly dissolved in
dichloromethane (20 mL), followed by addition of pyridinium
dichromate (PDC) (1.43 g, 3.8 mmol) and stirred for 5 h at
room temperature. The reaction mixture was filtered through
a pad of Celite and washed by EtOAc. The filtrate was dried
over MgSO4 and concentrated in vacuo. The residue was
purified by flash chromatography (EtOAc:n-hexane ) 1:3) to
afford the desired aldehyde 22 as a pale yellow solid (0.33 mg,
71%); mp 96 °C. 1H NMR (300 MHz, CDCl3): δ 3.96 (s, 3H,
OCH3), 7.71 (t, J ) 1.2 Hz, 1H), 7.97 (t, J ) 2.1 Hz, 1H), 8.28
(t, J ) 1.2 Hz, 1H), 10.03 (s, 1H).
2.1, 1H), 7.20 (d, J ) 1.8 Hz, 1H), 7.32 (d, J ) 8.1 Hz, 1H).13
C
NMR (CDCl3): δ 56.3, 61.0, 107.4, 116.3, 120.2, 123.0, 128.8,
132.2, 137.0, 141.7, 142.8, 152.5, 194.5. MS (EI) m/z: 321 (M+,
100%), 323 (M + 2, 38%). HRMS (EI) for C16H16ClNO4 (M+):
calcd, 321.0770; found, 321.0769. Anal. (C16H16ClNO4) C, H,
N.
(h ) (5-Am in o-2-ch lor oph en yl)(3,4,5-tr im eth oxyph en yl)-
m eth a n on e (10). The title compound was obtained in 64%
overall yield from 3,4,5-trimethoxyphenyl bromide and 2-chloro-
1
5-nitrobenaldehyde following procedures A-C. H NMR (300
MHz, CDCl3): δ 3.83 (s, 6H, 2 x OCH3), 3.91 (s, 3H, OCH3),
6.63 (d, J ) 3 Hz, 1H), 6.70 (dd, J ) 2.7, 8.4 Hz. 1H), 7.07 (s,
2H), 7.18 (d, J ) 8.4 Hz, 1H). MS (EI) m/z: 321 (M+, 100%),
323 (M + 2, 39%). HRMS (EI) for C16H16ClNO4 (M+): calcd,
321.0773; found, 321.0770. Anal. (C16H16ClNO4) C, H, N.
(n ) 4-Eth oxy-3-n itr oben za ld eh yd e (24). To a solution of
4-hydroxy-3-nitrobenzaldehyde (1.00 g, 5.98 mmol) in aceto-
nitrile (20 mL) were added potassium carbonate (1.65 g, 11.96
mmol) and ethyl iodide (1.00 mL, 11.96 mmol). The reaction
mixture was heated under reflux for 15 h and quenched by
cold water. The solution was extracted by EtOAc (15 mL × 3),
dried over MgSO4, and concentrated in vacuo. The residue was
further purified by flash chromatography (EtOAc:n-hexane )
1:3) to yield the desired aldehyde 24 as a white solid (0.95 g,
(i) (3-Am in o-4-eth oxyp h en yl)(3,4,5-tr im eth oxyp h en yl)-
m eth a n on e (11). The title compound was obtained in 62%
overall yield from 3,4,5-trimethoxyphenyl bromide and 4-ethoxy-
3-nitro- benaldehyde 24 following procedures A-C; mp 128-
1
129 °C. H NMR (300 MHz, CDCl3): δ 1.48 (t, J ) 7 Hz, 3H),
3.87 (s, 6H, 2 × OCH3), 3.94 (s, 3H, OCH3), 4.14 (q, J ) 7 Hz,
2H), 6.78 (d, J ) 8.4 Hz, 1H), 7.01 (s, 2H), 7.17 (dd, J ) 1.95,
8.2 Hz, 1H), 7.24 (d, J ) 2.1 Hz, 1H). 13C NMR (CDCl3): δ15.0,
56.3, 60.9, 64.0, 107.2, 109.5, 115.6, 122.1, 130.1, 133.3, 135.9,
141.0, 149.9, 152.4, 194.7. MS (EI) m/z: 331 (M+, 46%), 274
(100%). HRMS (EI) for C18H21NO5 (M+): calcd, 331.1416;
found, 331.1418. Anal. (C18H21NO5) C, H, N.
1
82%). H NMR (300 MHz, CDCl3): δ 1.52 (t, J ) 6.9 Hz, 3H),
4.29 (q, J ) 7.2 Hz, 2H), 7.19 (d, J ) 8.7 Hz, 1H), 8.05 (dd, J
) 8.7, 2.1 Hz, 1H), 8.31 (d, J ) 2.1 Hz, 1H), 9.91 (s, 1H). MS
(EI) m/z: 195 (M+, 100%)
(o) 3-Nitr o-4-p r op oxyben za ld eh yd e (25). The title com-
pound was obtained as a pale yellow solid in 80% yield in a
similar manner for the preparation of 24 by use of propyl iodide
(j) (3-Am in o-4-p r op oxyp h en yl)(3,4,5-tr im eth oxyp h en -
yl)m eth a n on e (12). The title compound was obtained in 70%
overall yield from 3,4,5-trimethoxyphenyl bromide and 3-nitro-
4-propoxybenaldehyde 25 following procedures A-C; mp 86
1
instead of ethyl iodide. H NMR (300 MHz, CDCl3): δ 1.09 (t,
J ) 7.5 Hz, 3H), 1.91 (m, J ) 7.2 Hz, 2H), 4.17 (t, J ) 6.3 Hz,
2H), 7.20 (d, J ) 8.7 Hz, 1H), 8.05 (dd, J ) 8.7, 2.1 Hz, 1H),
8.30 (d, J ) 1.8 Hz, 1H), 9.91 (s, 1H). MS (EI) m/z: 209 (M+,
100%).
1
°C. H NMR (300 MHz, CDCl3): δ 1.08 (t, J ) 7 0.5 Hz, 3H),
1.88 (h, J ) 7.5 Hz, 2H), 3.87 (s, 6H, 2 × OCH3), 3.92 (s, 3H,
OCH3), 4.04 (q, J ) 6.45 Hz, 2H), 6.79 (d, J ) 8.1 Hz, 1H),
7.01 (s, 2H), 7.18 (dd, J ) 2.1, 8.4 Hz, 1H), 7.25 (d, J ) 1.8
Hz, 1H). 13C NMR (CDCl3): δ10.7, 22.6, 56.3, 60.9, 69.9, 107.2,
109.5, 115.6, 122.1, 130.0, 133.3, 135.9, 141.0, 150.0, 152.3,
194.7. MS (EI) m/z: 345 (M+, 78%), 303 (100%). HRMS (EI)
for C19H23NO5 (M+): calcd, 345.1582; found, 345.1579. Anal.
(C19H23NO5) C, H, N.
(p ) 4-Isop r op oxy-3-n itr oben za ld eh yd e (26). The title
compound was obtained as pale white crystals in 73% yield in
a similar manner for the preparation of 24 by use of isopropyl
1
iodide instead of ethyl iodide. H NMR (300 MHz, CDCl3): δ
1.45 (d, J ) 6 Hz, 6H), 4.82 (m, J ) 6 Hz, 1H), 7.19 (d, J ) 8.7
Hz, 1H), 8.03 (dd, J ) 8.4, 1.8 Hz, 1H), 8.27 (d, J ) 2.1 Hz,
1H), 9.89 (s, 1H). MS (EI) m/z: 209 (M+, 100%).
(k ) (3-Am in o-4-isop r op oxyp h en yl)(3,4,5-t r im et h oxy-
p h en yl)m eth a n on e (13). The title compound was obtained
in 54% overall yield from 3,4,5-trimethoxyphenyl bromide and
4-isopropoxy-3-nitrobenaldehyde 26 following procedures A-C;
(C) Biology. (a ) Ma ter ia ls. Regents for cell culture were
obtained from Gibco-BRL Life Technologies (Gaitherburg,
MD). Microtubule-associated protein (MAP)-rich tubulin was
purchased from Cytoskeleton, Inc. (Denver, CO). [3H]Colchi-
cine (specific activity, 60-87 Ci/mmol) was purchased from
PerkinElmer Life Sciences (Boston, MA).
1
mp 98-99 °C. H NMR (300 MHz, CDCl3): δ 1.40 (d, J ) 5.7
Hz, 6H), 3.87 (s, 6H, 2 × OCH3), 3.93 (s, 3H, OCH3), 4.66 (p,
J ) 6.0 Hz, 1H), 6.79 (d, J ) 8.4 Hz, 1H), 7.01 (s, 2H), 7.17
(dd, J ) 2.1, 8.1 Hz, 1H), 7.24 (d, J ) 1.8 Hz, 1H). 13C NMR
(CDCl3): δ 22.2, 56.2, 60.9, 70.5, 107.2, 110.7, 115.8, 121.9,
129.8, 133.3, 136.5, 140.9, 148.7, 152.3, 194.6. MS (EI) m/z:
345 (M+, 30%), 303 (100%). HRMS (EI) for C19H23NO5 (M+):
calcd, 345.1566; found, 345.1571. Anal. (C19H23NO5) C, H, N.
(b) Cell Gr ow th In h ibitor y Assa y. Human oral epider-
moid carcinoma KB cells, colorectal carcinoma HT29 cells, and
stomach carcinoma TSGH were maintained in RPMI-1640
medium supplied with 5% fetal bovine serum. KB-VIN10 cells
were maintained in growth medium supplemented with 10 nM
vincristine, generated from vincristine-driven selection, and
displayed overexpression of P-gp170/MDR (unpublished data).
Cell in logarithmic phase were cultured at a density of 5000
cells/mL/well in a 24-well plate. KB-VIN10 cells were cultured
in drug-free medium for 3 days prior to use. The cells were
exposed to various concentrations of the test drugs for 72 h.
The methylene blue dye assay was used to evaluate the effect
of the test compounds on cell growth as described previously.20
The IC50 value resulting from 50% inhibition of cell growth
was calculated graphically as a comparison with the control.
Compounds were examined in at least three independent
experiments, and the values shown for these compounds are
the mean and standard deviation of these data.
(c) Tu bu lin P olym er iza tion in Vitr o Assa y. Turbidi-
metric assays of microtubules were performed as described by
Bollag et al.21 MAP-rich tubulin (2 mg/mL) in 100 µL buffer
containing 100 mM PIPES (pH 6.9), 2 mM MgCl2, 1 mM GTP,
and 2% (v/v) dimethyl sulfoxide were placed in 96-well micro-
titer plate in the presence of test compounds. The increase in
absorbance was measured at 350 nm in a PowerWave X
Microplate Reader (BIO-TEK Instruments, Winooski, VT) at
(l) 2-Meth oxy-5-(3,4,5-tr im eth oxyben zyl)p h en yla m in e
(14). To a solution of 5 (0.20 g, 0.63 mmol) in dichloromethane
(10 mL) was added sodium borohydride (0.05 g, 1.26 mmol) at
room temperature. After 10 min, trifluoroacetic acid (0.23 mL,
3.15 mmol) was added dropwise to the reaction mixture. The
reaction was stirred for 16 h at room temperature. The mixture
was diluted with cold sat. NaHCO3 and extracted into CH2Cl2
(10 mL × 3). The solvents were evaporated, and the concen-
trate was purified by flash column on silica gel eluting with
15:1 CH2Cl2/MeOH to yield the desired product as a yellow
1
solid (0.12 g, 62%). H NMR (300 MHz, CDCl3): δ 3.80-3.84
(m, 14H), 6.38 (s, 2H), 6.52-6.56 (m, 2H), 6.71 (d, J ) 7.8 Hz,
1H). MS (EI) m/z: 303 (M+, 100). 13C NMR (CDCl3): δ 41.6,
55.4, 55.9, 60.7, 105.5, 110.0, 115.2, 118.2, 133.2, 135.7, 137.0,
145.4, 152.6. MS (EI) m/z: 345 (M+, 30%), 303 (100%). HRMS
(EI) for C19H23NO5 (M+): calcd, 345.1566; found, 345.1571.
Anal. (C19H23NO5) C, H, N.Anal. (C17H21NO4) C, H, N.
(m ) 3-Meth oxy-5-n itr oben za ld eh yd e (22). To a stirred
solution of 3-methoxy-5-nitrobenzoic acid (0.50 g, 2.53 mmol)
in tetrahydrofuran at 0 °C was added 1.0 M BH3/THF (13 mL,
12.65 mmol) dropwise. This solution was allowed to stir at

2904 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 11
Liou et al.
Okano, A.; Tsuji, T.; Akiyama, Y.; Tsuruo, T.; Saito, S.; Hori,
K.; Sato, Y. Evaluation of Antivascular and Antimitotic Effects
of Tubulin Binding Agents in Solid Tumor Therapy. J pn. J .
Cancer Res. 1999, 90, 1387-1395.
37 °C and recorded every 30 s for 30 min. The area under the
curve (AUC) used to determine the concentration that inhib-
ited tubulin polymerization to 50% (IC50). The AUC of the
untreated control and 10µM of colchicine was set to 100% and
0% polymerization, respectively, and the IC50 was calculated
by nonlinear regression in at least three experiments.22
(d ) [3H] Colch icin e Bin d in g Assa y. The assay was
basically performed according to the method of Lambeir and
Engelborghs.23 MAP-rich tubulin was incubated with [3H]-
colchicine in the presence of various concentrations of test
compounds in a buffer containing 0.05 M PIPES (pH 6.9), 1
mM MgCl2, and 1 mM GTP. After incubating at room tem-
perature for 1 h, the samples were centrifuged through
Sephadex G-50 columns (Amersham Biosciences, Piscataway,
NJ ). The eluates in the flow-through were analyzed for
radioactivity by scintillation counting.
(10) (a) Hill, S. A.; Chaplin, D. J .; Lewis, G.; Tozer, G. M. Schedule
Dependence of Combretastatin A4 Phosphate in Transplated and
Spontaneous Tumor Models. Int. J . Cancer 2002, 102, 70-74.
(b) Boehle, A. S.; Sipos, B.; Kliche, U.; Kalthoff, H.; Dohrmann,
P. Combretastatin A-4 Prodrug Inhibits Growth of Human Non-
Small Cell Lung Cancer in a Murine Xenotransplant Model. Ann.
Thorac. Surg. 2001, 71, 1657-1665.
(11) (a) Morinaga, Y.; Suga, Y.; Ehara, S.; Harada, K.; Nihei, Y.;
Suzuki, M. Combination Effect of AC-7700, a Novel Combret-
astatin A-4 Derivative, and Cisplatin against Murine and
Human Tumors in Vivo. Cancer Sci. 2003, 94, 200-204. (b) Li,
L.; Rojianai, A. M.; Siemann, D. W. Preclinical Evaluations of
Therapies Combining the Vascular Targeting Agent Combret-
astatin A-4 Disodium Phosphate and Conventional Anticancer
41Therapies in the Treatment of Kaposi’s Sarcoma. Acta Oncol.
2002, 41, 91-97. (c) Grosios, K.; Loadman, P. M.; Swaine, D. J .;
Pettit, G. R.; Bibby, M. C. Combination Chemotherapy with
Combretastatin A-4 Phosphate and 5-Fluorouracil in an Experi-
mental Murine Colon Adenocarcinoma. Anticancer Res. 2000,
20, 29-234. (d) Nelkin, B. D.; Ball, D. W. Combretastatin A-4
Ack n ow led gm en t. We thank Dr. Chun-Chen Liao
of National Tsing Hua University for his valuable
suggestions concerning the manuscript and Mr. Yu-
Ching Liu for his technical assistance. The authors are
also grateful to National Health Research Institutes,
Taiwan, Republic of China for financial support.
and Doxorubicin Combination Treatment is Effective in
a
Preclinical Model of Human Medullary Thyroid Carcinoma.
Oncol. Rep. 2001, 8, 157-160. (e) Murata, R.; Overgaard, J .;
Horsman. M. R. Combretastatin A-4 Disodium Phosphate:
a
Vascular Targeting Agent that Improves the Antitumor Effects
of Hyperthermia, Radiation, and Mild Thermoradiotherapy. Int.
J . Radiat. Oncol. Biol. Phys. 2001, 51, 1018-1024.
Su p p or tin g In for m a tion Ava ila ble: Elemental analyses
data are available for compounds 3, 5-14. The material is
available free of charge via the Internet at http://pubs.acs.org.
(12) For CA-4 analogues: (a) Shirai, R.; Takayama, H.; Nishikawa,
A.; Koiso, Y.; Hashimoto, Y. Asymmetric Synthesis of Antimitotic
Combretadioxolane with Potent Antitumor Activity Against
Multi-Drug Resistant Cells. Bioorg. Med. Chem. Lett. 1998, 8,
1997-2000. (b) Wang, L.; Woods, K. W.; Li, Q.; Barr, K. J .;
McCroskey, R. W.; Hannick, S. M.; Gherke, L.; Credo, R. B.; Hui,
Y. H.; Marsh, K.; Warner, R.; Lee, J . Y.; Zielinski-Mozng, N.;
Frost, D.; Rosenberg, S. H.; Sham, H. L. Potent, Orally Active
Heterocycle-based Combretastatin A-4 Analogues: Synthesis,
Structure-Activity Relationship, Pharmacokinetics, and in Vivo
Antitumor Activity Evaluation. J . Med. Chem. 2002, 45, 1697-
1711. (b) Szczepankiewicz, B. G.; Liu, G.; J ae, H. S.; Tasker, A.
S.; Gunawardana, I. W.; von Geldern, T. W.; Gwaltney, S. L. II;
Wu-Wong, J . R.; Gehrke, L.; Chiou, W. J .; Credo, R. B.; Alder,
J . D.; Nukkala, M. A.; Zielinski, N. A.; J arvis, K.; Mollison, K.
W.; Frost, D. J .; Bauch, J . L.; Hui, Y. H.; Claiborne, A. K.; Li,
Q.; Rosenberg, S. H. New Antimitotic Agents with Activity in
Multi-Drug-Resistant Cell Lines and in Vivo Efficacy in Murine
Tumor Models. J . Med. Chem. 2001, 44, 4416-4430. (c) Pinney,
K. G.; Bounds A. D.; Dingeman, K. M.; Mocharla, V. P.; Pettit,
G. R.; Bai, R.; Hamel, E. A New Anti-Tubulin Agent Containing
The Benzo[b]thiophene Ring System. Bioorg. Med. Chem. Lett.
1999, 9, 1081-1086. (d) Flynn, B. L.; Hamel, E.; J ung, M. K.
One-Pot Synthesis of Benzo[b]furan and Indole Inhibitors of
Tubulin Polymerization. J . Med. Chem. 2002, 45, 2670-2673.
(13) (a) Mahboobi; S.; Pongratz; H.; Hufsky; H.; Hockemeyer; J .;
Frieser; M.; Lyssenko; A.; Paper; D. H.; Bu¨rgermeister; J .;
Bo¨hmer; F. D.; Fiebig; H. H.; Burger; A. M.; Baasner; S.; Beckers;
T. Synthetic 2-Aroylindole Derivatives as a New Class of Potent
Tubulin-Inhibitory; Antimitotic Agents. J . Med. Chem. 2001, 44,
4535-4553. (b) Beckers; T.; Reissmann; T.; Schmidt; M.; Burger;
A. M.; Fiebig; H. H.; Vanhoefer; U.; Pongratz; H.; Hufsky; H.;
Hockemeyer; J .; Frieser; M.; Mahboobi; S. 2-Aroylindoles; a
Novel Class of Potent; Orally Active Small Molecule Tubulin
Inhibitors. Cancer Res. 2002, 62, 3113-3119.
(14) (a) Hori, K.; Saito, S. Microvascular Mechanisms by which the
Combretastatin A-4 Derivative AC7700 (AVE8062) Induces
Tumor Blood Flow Stasis. Br. J . Cancer 2003, 89, 1334-1344.
(b) Hori, K.; Saito, S.; Sato, Y.; Akita, H.; Kawaguchi, T.;
Sugiyama, K.; Sato, H. Differential Relationship between Changes
in Tumour Size and Microcirculatory Functions Induced by
Therapy with an Antivascular Drug and with Cytotoxic Drugs:
Implications for the Evaluation of Therapeutic Efficacy of
AC7700 (AVE8062). Eur. J . Cancer 2003, 39, 1957-1966. (c)
Nihei, Y.; Suga, Y.; Morinaga, Y.; Ohishi, K.; Okano, A.; Ohsumi,
K.; Hatanaka, T.; Nakagawa, R.; Tsuji, T.; Akiyama, Y.; Saito,
S.; Hori, K.; Sato, Y.; Tsuruo, T. A Novel Combretastatin A-4
Derivative, AC-7700, Shows Marked Antitumor Activity against
Advanced Solid Tumors and Orthotopically Transplanted Tu-
mors. J pn. J . Cancer Res. 1999, 90, 1016-1025.
Refer en ces
(1) Li, Q.; Sham, H. L. Discovery and Development of Antimitotic
Agents That Inhibit Tubulin Polymerisation for the Treatment
of Cancer. Expert Opin. Ther. Pat. 2002, 12, 1663-1702.
(2) Hamel, E. Antimitotic Natural Products and Their Interactions
with Tubulin. Med. Res. Rev. 1996, 16, 207-231.
(3) Pettit, G. R.; Cragg, G. M.; Herald, D. L.; Schmidt, J . M.;
Lohavanijaya, P. Isolation and Structure of Combretastatin.
Can. J . Chem. 1982, 60, 1374-1376.
(4) McGown, A. T.; Fox, B. W. Differential Cytotoxicity of Combre-
tastatins A1 and A4 in Two Daunorubicin-Resistant P388 Cell
Lines. Cancer Chemother. Pharmacol. 1990, 26, 79-81.
(5) (a) Tozer, G. M.; Kanthou, C.; Parkins, C. S.; Hill, S. A. The
Biology of the Combretastatins as Tumour Vascular Targeting
Agents. Int. J . Exp. Pathol. 2002, 83, 21-38. (b) Griggs, J .;
Metcalfe, J . C.; Hesketh, R. Targeting Tumour Vasculature: the
Development of Combretastatin A4. Lancet. Oncol. 2001, 2, 82-
87.
(6) Nam, N. H. Combretastatin A-4 Analogues as Antimitotic
Antitumor Agents. Curr. Med. Chem. 2003, 10, 1697-1722.
(7) For CA-4 derivatives: (a) Pettit, G. R.; Rhodes, M. R. Antine-
oplastic Agents 389. New Syntheses of the Combretastatin A-4
Produrg. Anti-Cancer Drug Design 1998, 13, 183-191. (b) Pettit,
G. R.; Lippert, J . W., III. Antineoplastic Agents 429. Syntheses
of the Combretastatin A-1 and Combretastatin B-1 Produrgs.
Anti-Cancer Drug Des. 2000, 15, 203-216. (c) Ohsumi, K.;
Nakagawa, R.; Fukuda, Y.; Hatanaka, T.; Morinaga, Y.; Nihei,
Y.; Ohishi, K.; Suga, Y.; Akiyama, Y.; Tsuji, T. Novel Combre-
tastatin Analogues Effective against Murine Solid Tumors:
Design and Structure-Activity Relationships. J . Med. Chem.
1998, 41, 3022-3032. (d) Pettit, G. R.; Toki, B.; Herald, D. L.;
Verdier-Pinard, P.; Boyd, M. R.; Hamel, E.; Pettit, R. K.
Antineoplastic Agents. 379. Synthesis of Phenstatin Phosphate.
J . Med. Chem. 1998, 41, 1688-1695.
(8) (a) Dark, G. G.; Hill, S. A.; Prise, V. E.; Tozer, G. M.; Pettit, G.
R.; Chaplin, D. J . Combretastatin A-4, an Agent that Displays
Potent and Selective Toxicity toward Tumor Vasculature. Cancer
Res. 1997, 57, 1829-1834. (b) Tozer, G. M.; Prise, V. E.; Wilson,
J .; Locke, R. J .; Vojnovic, B.; Stratford, M. R. L.; Dennis, M. F.;
Chaplin, D. J . Combretastatin A-4 Phosphate as
a Tumor
Vascular-Targeting Agent: Early Effects in Tumors and Normal
Tissues. Cancer Res. 1999, 59, 1626-1634. (c) Hill, S. A.; Tozer,
G. M.; Pettit, G. R.; Chaplin, D. J . Preclinical Evaluation of the
Antitumor Activity of the Novel Vascular Targeting Agent Oxi
4503. Anticancer Res. 2002, 22, 1453-1458.
(9) (a) Hori, K.; Saito, S.; Kubota, K. A Novel Combretastatin A-4
Derivative, AC-7700, Strongly Stanches Tumour Blood Flow and
Inhibits Growth of Tumors Developing in Various Tissues and
Organs. Br. J . Cancer 2002, 86, 1604-1614. (b) Hori, K.; Saito,
S.; Nihei, Y.; Suzuki, M.; Sato, Y. Antitumor Effects Due to
Irreversible Stoppage of Tumor Tissue Blood Flow: Evaluation
of a Novel Combretastatin A-4 Derivative, AC-7700. J pn. J .
Cancer Res. 1999, 90, 1026-1038. (c) Nihei, Y.; Suzuki, M.;
(15) Thorpe, P. E.; Chaplin, D. J .; Blakey, D. C. The First Interna-
tional Conference on Vascular Targeting: Meeting Overview.
Cancer Res. 2003, 63, 1144-1147.
(16) (a) Liou, J . P.; Chang, C. W.; Song, J . S.; Yang, Y. N.; Yeh, C.
F.; Tseng, H. Y.; Lo, Y. K.; Chang, Y. L.; Chang, C. M.; Hsieh,
H. P. Synthesis and Structure-Activity Relationship of 2-Ami-
nobenzophenone Derivatives as Antimitotic Agents. J . Med.

3-Aminobenzophenones as Antimitotic Agents
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 11 2905
Chem. 2002, 45, 2556-2562. (b) Hsieh, H. P.; Liou, J . P.; Lin,
Y. T.; Mahindroo, N.; Chang, J . Y.; Yang, Y. N.; Chern, S. S.;
Tan, U. K.; Chang, C. W.; Chen, T. W.; Lin, C. H.; Chang, Y. Y.;
Wang, C. C. Structure-Activity and Crystallographic Analysis
of Benzophenone Derivatives - the Potential Anticancer Agents.
Bioorg. Med. Chem. Lett. 2003, 13, 101-105.
(20) Finlay, G. J .; Baguley, B. C.; Wilson, W. R. A Semiautomated
Microculture Method for Investigating Growth Inhibitory Effects
of Cytotoxic Compounds on Exponentially Growing Carcinoma
Cells. Anal. Biochem. 1984, 139, 272-277.
(21) Bollag, D. M.; McQueney, P. A.; Zhu, J .; Hensens, O.; Koupal,
L.; Liesch, J .; Goetz, M.; Lazarides, E.; Woods, C. M. Epothilones,
a New Class of Microtubule-stabilizing Agents with a Taxol-like
Mechanism of Action. Cancer Res. 1995, 55, 2325-2333.
(22) Chang, J . Y.; Hsieh, H. P.; Pan, W. Y.; Liou, J . P.; Bey, S. J .;
Chen, L. T.; Song, J . S. Dual Inhibition of Topoisomerase I and
Tubulin Polymerization by BPR0Y007, a Novel Cytotoxic Agent.
Biochem. Pharmacol. 2003, 65, 2009-2019.
(17) Meindl, W. R.; Angerer, E. V.; Scho¨nenberger, H.; Ruckdeschel,
G. Benzylamines: Synthesis and Evaluation of Antimycobacte-
rial Properties. J . Med. Chem. 1984, 27, 1111-1118.
(18) Herlt, A. J .; Kibby, J . J .; Rickards, R. W. Synthesis of Unlabeled
and Carboxyl-Labeled 3-Amino-5-hydroxybenzoic Acid. Aust. J .
Chem. 1981, 34, 1319-1324.
(19) Cushman, M.; Nagarathnam, D.; Gopal, D.; Lin, C. M.; Hamel,
E. Synthesis and Evaluation of Analogues of (Z)-1-(4-Meth-
oxyphenyl)-2-(3,4,5-trimethoxyphenyl)ethane as Potential Cy-
totoxic and Antimitotic Agents. J . Med. Chem. 1992, 35, 2293-
2306.
(23) Lambier, A.; Engelborghs, Y. A Quantitative Analysis of Tubulin-
colchicine Binding to Microtubules. Eur. J . Biochem. 1980, 109,
619-624.
J M0305974