Synthesis and in-vitro biological activity of macrocyclic urea Chk1 inhibitors

Article abstract of DOI:10.1016/j.bmcl.2007.09.088

A variety of macrocyclic urea compounds were prepared as potent Chk1 inhibitors by modifying the C5 position of the benzene ring of the macrocyclic urea with ether moieties, aliphatic carbon chains, amide and halides. Enzymatic activity less than 20 nM was observed in 29 of 40 compounds. Compounds 14, 46d, and 48j provided the best overall results in the cellular assays as they abrogated doxorubicin-induced cell cycle arrest (IC₅₀ = 3.31, 3.08, and 3.13 μM) and enhanced doxorubicin cytotoxicity (IC₅₀ = 0.54, 1.27, and 0.96 μM) while displaying no single agent activity, respectively.

Full text of DOI:10.1016/j.bmcl.2007.09.088

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry Letters 17 (2007) 6499–6504
Synthesis and in-vitro biological activity of macrocyclic
urea Chk1 inhibitors
Gaoquan Li,* Zhi-Fu Tao, Yunsong Tong, Magdalena K. Przytulinska, Peter Kovar,
Philip Merta, Zehan Chen, Haiying Zhang, Thomas Sowin,
Saul H. Rosenberg and Nan-Horng Lin
Cancer Research, Global Pharmaceutical Research & Development, Abbott Laboratories, Abbott Park, IL 60064, USA
Received 9 August 2007; revised 24 September 2007; accepted 26 September 2007
Available online 29 September 2007
Abstract—A variety of macrocyclic urea compounds were prepared as potent Chk1 inhibitors by modifying the C5 position of the
benzene ring of the macrocyclic urea with ether moieties, aliphatic carbon chains, amide and halides. Enzymatic activity less than
20 nM was observed in 29 of 40 compounds. Compounds 14, 46d, and 48j provided the best overall results in the cellular assays as
they abrogated doxorubicin-induced cell cycle arrest (IC50 = 3.31, 3.08, and 3.13 lM) and enhanced doxorubicin cytotoxicity
(IC50 = 0.54, 1.27, and 0.96 lM) while displaying no single agent activity, respectively.
Ó 2007 Elsevier Ltd. All rights reserved.
More than 50% of cancer cells have mutant p53 and are
O
5
2
5
R
X
O
O
not capable of arresting in the G1 checkpoint.1 As a re-
sult, cancer cells rely on Chk1-dependent S and G2
checkpoints to cope with DNA damages.2–4 Inhibition
of Chk1 abrogates the S and G2 checkpoints and leads
to premature mitotic progression and mitotic catastro-
phe when combined with a DNA damaging agent.5–7
In contrast, normal cells still arrest at G1, via p53, to re-
pair their DNA damages. Therefore, Chk1 inhibitors
should selectively sensitize cancer cells to DNA damag-
ing reagents2–4,8 and be of great therapeutic value in
cancer treatment.
4
4
NH
O
R
R
O
N
O
N
O
N
O
N
N
NH
N
NH
N
NH
H
H
H
N
NH
R
H
R
N
N
N
N
CN
CN
CN
CN
1
2
3
4
Figure 1. Structure of compounds 1, 2, 3, and 4.
patent literature,14,18–20 we synthesized macrocyclic urea
compounds21,22 (2, Fig. 1). Since acyclic ureas with eth-
oxy (3, Fig. 1, IC50 = 31 nM) and amide (4, Fig. 1,
IC50 = 22 nM) substitution at the R5 position were ac-
tive in the Chk1 enzymatic assay, we modified R5 on
the benzene ring of the macrocyclic urea. The chemistry
and biological results of these modifications are pre-
sented here.
Several compounds are already known as Chk1 inhibi-
tors.9–12 UCN-01 is undergoing clinical trials as an anti-
cancer agent.13 Recently, we,14–17 and others,18–20 have
disclosed N-aryl-N0-pyrazinyl ureas (1, Fig. 1) as a
new class of Chk1 inhibitors. Much of our effort was fo-
cused on the modification of R2, which points toward
the ribose pocket of the Chk1 enzyme, and R4, which
points toward the solvent front. Hundreds of acyclic
urea compounds we synthesized showed single-digit
nM enzymatic activity and excellent selectivity.14–16 Be-
cause diaryl ureas have been explored extensively in the
Scheme 1 shows the initial synthesis of the macrocyclic
ureas. After the protection of 2,4-dimethoxyaniline 7
with phthalic anhydride and demethylation with BBr3,
the C5-hydroxy of intermediate 8 was selectively pro-
tected with a TBDPS group, and subsequent allylation
of the C2-hydroxy of intermediate 9 afforded compound
10. Deprotection of compound 10 with hydrazine fol-
lowed by coupling with intermediate 5 (Fig. 2) provided
acyclic urea 12. Grubbs cyclization afforded compound
Keywords: Macrocyclic urea; Chk1 inhibitor.
*
Corresponding author. Tel.: +1 608 265 8216; fax: +1 608 265
4534; e-mail: gaoquanli@wisc.edu
0960-894X/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2007.09.088

6500
G. Li et al. / Bioorg. Med. Chem. Lett. 17 (2007) 6499–6504
from the reaction of compound 26 with morpholine
OH
O
O
Si
via step h) and subsequent deprotection with hydrazine
afforded amino intermediates 22 and 28. The Mitsunobu
reaction of compound 16 with 4-bromo-1-butanol fol-
lowed by substitution and deprotection produced amino
intermediate 25. Compound 29 was converted to the
amino intermediate 33 in four steps via global acetyla-
tion of compound 29; selective removal of the acetyl
group from the resulting phenolic ester; allylation of
O
a,b
c
O
O
95%,90%
N
83%
NH2
OH
N
O
OH
O
7
8
9
Si
O
Si
O
Si
O
O
N
d
e
36%
f
O
89%
88%
N
H
NH
O
N
NH2
O
O
N
O
OH
O
O
O
O
10
11
12
CN
O
a
b
O
c
10
56%
N
52%
97%
N
OH
NH2
N
Si
O
O
O
O
O
O
O
O
O
N
16
17
18
g
h
i
N
NH
N
NH
H
O
O
O
N
NH
100%
57%
2%
H
O
N
O
H
O
N
N
d
c
O
O
N
16
16
N
O
46%
88%
CN
N
O
NH2
N
CN
CN
O
13
14
15
O
19
20
Scheme 1. Reagents and conditions: (a) phthalic anhydride, 180 °C,
15 min; (b) BBr3, CH2Cl2, ꢀ78 to 0 °C, 2 h; (c) tert-butylchlorodiphe-
nylsilane, imidazole, DMF, 50 °C, 72 h; (d) allyl bromide, K2CO3,
acetone, reflux, 12 h; (e) H2NNH2, CH3OH, rt, 2 h; (f) 5, DMF, 70 °C,
12 h; (g) Grubbs catalyst, 2nd generation, CH2Cl2, 40 °C, 12 h; (h)
TBAF, THF, rt, 3 h; (i) 2-dimethylamino-ethanol, di-tert-butylazodi-
carboxylate, PPh3-polymer supported, THF, rt, 12 h.
O
O
N
O
O
O
O
e
c
O
91%
84%
N
NH2
O
21
22
O
O
Br
O
O
N
N
O
O
O
O
f
g
c
O
16
O
85%
36%
81%
N
O
O
N
NH2
O
HN
O
HN
O
O
N
N
25
23
24
N
N
O
O
O
N
CN
CN
O
h
i,c
HO
N
5
6
HO
Br
O
80%
93%,92%
NH2
O
Figure 2. Structure of intermediates 5 and 6, synthesized according to
Ref. 21.
26
28
27
O
O
O
O
NH2
NH
NH
NH
NH
j
k
l
m
13. TBAF deprotection provided compound 14. Mitsun-
obu reaction gave compound 15.
74% for
3 steps
80%
NO2
NO2
Br
NO2
NH2
NO2
OH
29
O
O
O
OH
O
32
30
31
33
Since the Mitsunobu reaction in Scheme 1 did not work
well, we used an alternate strategy in Scheme 2. Com-
pound 10 was deprotected with TBAF to give com-
pound 16, which was then alkylated, and deprotected
with hydrazine to provide amino intermediates 18 and
20. The Mitsunobu reactions of compound 16 with 3-
morpholinopropanol and 5-morpholinopentanol (made
Br
Br
n
m
85%
97%
NH2
NO2
NO2
34
O
36
O
35
F
X
X
X
l
m
82-95%
88-96%
NO2
NH2
NO2
O
O
OH
c
Scheme 2. Reagents and conditions: (a) TBAF, THF, rt, 3 h; (b)
iodomethane, K2CO3, acetone, reflux, 3 h; (c) H2NNH2, CH3OH, rt,
2 h; (d) iodoethane, K2CO3, acetone, reflux, 3 h; (e) 3-morpholino-
propanol, di-tert-butylazodicarboxylate, PPh3-polymer supported,
THF, rt, 12 h; (f) 4-bromo-1-butanol, di-tert-butylazodicarboxylate,
PPh3-polymer supported, THF, rt, 12 h; (g) morpholine, triethylamine,
CH3CN, 60 °C, 12 h; (h) morpholine, CH3CN, 80 °C, 12 h; (i) 16, di-
tert-butylazodicarboxylate, PPh3-polymer supported, THF, rt, 12 h; (j)
acetyl chloride, pyridine, rt, 12 h; (k) K2CO3, MeOH, rt, 72 h; (l) allyl
bromide, K2CO3, acetone, reflux, 6 h; (m) Fe, NH4Cl, EtOH, H2O,
80 °C, 3 h; (n) allyl alcohol, NaH, THF, rt, 12 h; (o) 6, DMF, 70 °C,
12 h; (p) Grubbs catalyst, 2nd generation, CH2Cl2, 40 °C, 12 h; (q)
Rh(I)(PPh3)3Cl, 60 psi H2, THF, rt, 72 h; (r) 5, DMF, 70 °C, 12 h; (s)
5% Pt/C, THF, 50 psi H2, rt, 3 h.
38: X=H
41: X=H
42: X=Cl
43: X=Me
37
39: X=Cl
40: X=Me
R5
R5
R5
O
O
O
N
o
p
q
22, 25,
28, 42
N
NH
N
H
NH
N
H
NH
H
O
O
O
54-94%
31-100%
57-100%
N
N
N
N
N
O
O
O
CN
CN
CN
44
45
46
R5
R5
R5
O
18, 20,
22, 25,
28, 33,
36, 41,
42, 43
O
N
O
N
O
r
s
37-69%
p
N
H
NH
N
H
NH
N
NH
H
O
O
59-100%
27-94%
N
N
N
N
O
O
O
CN
CN
CN
48
49
47

G. Li et al. / Bioorg. Med. Chem. Lett. 17 (2007) 6499–6504
6501
the phenol; and finally iron reduction of the nitro group.
Amino intermediate 36 was synthesized by substitution
and reduction of compound 34. Amino intermediates
41–43 were made through allylation and reduction.
Intermediates 22, 25, 28, and 42 were coupled with inter-
mediate 6 (Fig. 2) separately to afford the corresponding
acyclic ureas. After Grubbs cyclization and hydrogena-
tion, 14-membered ring macrocyclic urea compounds
45a–d and 46a–d were obtained. Moreover, all the ami-
no intermediates in Scheme 2 were coupled with inter-
mediate 5 separately to afford all the corresponding
acyclic urea intermediates. Grubbs cyclization and
hydrogenation provided the 15-membered ring macro-
cyclic urea compounds 48a–j and 49a–j.
ded compound 54. Hydrogenation followed by urea
coupling and Mitsunobu reaction provided acyclic urea
intermediate 57. A triple bond was introduced on the
bromo site of intermediate 51 via the Sonogashira
reaction and intermediate 58 was made. After hydroge-
nation, urea coupling and Mitsunobu reaction, interme-
diate 61 was obtained. Alkylation of compound 16
followed by hydrazine deprotection and urea coupling
afforded intermediate 64. Intermediates 57, 61, and 64
were cyclized to produce compounds 65a–c. THP depro-
tection provided compounds 66a–c. Hydrogenation
afforded compounds 67a–c.
NMR analysis confirmed that the Grubbs cyclization
here provided the cis conformation. The enzymatic
activities14–16,21 of the macrocyclic urea compounds
are listed in Table 1. Compound 13 showed no enzy-
matic activity because the TBDPS group prevented
binding to the enzyme.
As shown in Scheme 3, several alcohol groups were
introduced at the C5 position. Starting material 50 was
benzylated to give intermediate 51. The bromo moiety
was then replaced with vinyl via Stille coupling. After
hydroboration and oxidation, a hydroxyethyl group
was introduced at this position. THP protection affor-
In most cases, the enzymatic activities of the macrocyclic
ureas before and after the hydrogenation of the cycliza-
tion chain are comparable. For example, compounds
45b and 46b both possess IC50 = 4 nM. The other corre-
sponding pairs generally follow the same trend. This
indicates that the hydrogenation of the cyclization chain
did not have a significant effect on the enzymatic activ-
ity. Also, the enzymatic activities of the 15-membered
ring macrocyclic ureas and 14-membered ring macrocy-
clic ureas with the same side group R5 are essentially
equivalent. For example, the corresponding 14-mem-
bered ring versus 15-membered ring pairs of compounds
48c and 45a, 49d and 46b, 49e and 46c have similar
IC50’s. We did not make 16-membered ring macrocyclic
urea compounds here because they are 4- to 5-fold less
than active the 14- and 15-membered ring macrocyclic
urea compounds.22
Br
Br
OH
O
O
b
a
c,d
e
91%
96%
94%
63% for
2 steps
NO2
NO2
NO2
NO2
NO2
OH
OBn
OBn
OBn
OBn
52
50
51
53
54
O
O
O
O
O
O
O
N
O
N
f
g
h
N
H
NH
N
H
NH
47%
77%
88%
OH
O
NH2
OH
N
N
O
O
CN
CN
55
56
57
O
O
O
O
O
O
O
O
O
O
N
i
f
g
h
N
H
NH
N
H
NH
51
57%
36%
100%
94%
OH
O
NH2
N
NO2
OH
N
N
O
O
Comparison of compounds 65a and 66a, compounds 65b
and 66b, and finally compounds 65c and 66c shows that
the enzymatic activity does not change significantly upon
THP deprotection. Also, increasing the side chain by one
methylene group does not cause appreciable change in
the enzymatic activity. Compounds 45a and 45b and
the other analogous pairs have similar IC50’s. This indi-
cates that R5 may be near to or occupy a position in free
space because the enzymatic activity was not sensitive to
the length of the side chain. This is consistent with the X-
ray crystallography data reported in Ref. 16.
OBn
CN
CN
58
59
60
61
O
O
O
O
O
O
O
O
O
O
O
O
j
k
53%
g
O
N
NH
16
H
81%
27%
O
N
NH2
N
N
O
O
CN
62
63
64
R5/THP
R5/OH
R5/OH
O
N
O
N
O
N
l
n
m
N
NH
N
NH
N
NH
57, 61, 64
H
O
H
H
O
O
30-47%
43-100%
23-70%
N
N
N
O
O
O
Comparison of the enzymatic activity of compound
65b–65c, compound 66b–66c, and finally compound
67b–67c shows that in each case the latter of the pair
is more active than the former. The only difference be-
tween these two types of compounds is that compounds
65b, 66b, and 67b have a methylene group directly at-
tached to the C5 position, while compounds 65c, 66c,
and 67c have an oxygen atom at this position. Obvi-
ously, oxygen provides a better interaction between the
small molecule and the enzyme.
CN
CN
CN
65
66
67
Scheme 3. Reagents and conditions: (a) benzylbromide, K2CO3,
acetone, reflux, 3 h; (b) tributyl(vinyl)tin, Pd(PPh3)4, DMF, 80 °C,
12 h; (c) 9-BBN, THF, rt, 12 h; (d) NaOH, H2O2, rt, 6 h; (e) 3,4-
dihydro-2H-pyran, p-TsOHÆH2O, CH2Cl2, rt, 12 h; (f) 20% Pd(OH)2/
C, 60 psi H2, CH3OH, 50 °C, 4 h; (g) 5, DMF, 70 °C, 12 h; (h) allyl
alcohol, di-tert-butylazodicarboxylate, PPh3-polymer supported, THF,
rt, 12 h; (i) tetrahydro-2-(2-propynyloxy)-2H-pyran, Pd(PPh3)2Cl2,
PPh3, CuI, triethylamine, 120 °C, 25 min, microwave; (j) 2-(2-bromo-
ethoxy)-tetrahydro-2H-pyran, K2CO3, acetone, reflux, 3 h; (k)
H2NNH2, CH3OH, rt, 2 h; (l) Grubbs catalyst, 2nd generation,
CH2Cl2, 40 °C, 12 h; (m) CH3CO2H/THF/H2O (4:2:1), 45 °C, 12 h; (n)
5% Pt/C, THF, 50 psi H2, rt, 3 h.
Comparing compounds 48c–e with compound 14, one
can calculate that compounds 48c–e are 6.80-, 5.67-,

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G. Li et al. / Bioorg. Med. Chem. Lett. 17 (2007) 6499–6504
Table 1. Chk1 IC50’s of 15-membered ring and 14-membered ring macrocyclic urea compounds before and after the hydrogenation of the cyclization
chain
R5
O
R5
O
R5
R5
O
N
O
N
O
N
O
N
N
H
NH
N
H
NH
N
H
NH
N
H
NH
(I)
(II)
(III)
(IV)
O
O
N
N
N
N
O
O
O
O
CN
CN
CN
CN
R5
I
II
III
IV
a
a
a
a
Compound
Chk1 IC50
(nM)
Compound
Chk1 IC50
(nM)
Compound
Chk1 IC50
(nM)
Compound
Chk1 IC50
(nM)
13
>10,000
Si
O
–OH
14
15
34
15
N
O
O
48a
48b
48c
37
19
5
49a
49b
49c
25
55
7
O
O
O
45a
45b
45c
4
4
2
46a
46b
46c
2
4
3
N
O
48d
48e
48f
6
49d
49e
49f
3
3
8
O
O
N
O
5
N
H
N
O
16
–Br
–H
–Clb
–Me
48g
48h
48i
48j
12
12
10
15
49g
49h
49i
49j
12
16
11
8
45d
5
46d
6
65a
66a
65b
108
97
O
O
67a
67b
67c
39
24
11
OH
91
O
O
O
66b
69
OH
O
O
65c
66c
19
13
O
OH
a Radiometric assay in the presence of 5 lM of ATP.
b See Ref. 22.
and 6.80-fold more active than compound 14 in the
enzymatic assay. However, comparing compounds 15,
48a, 48b, 65c, and 66c with compound 14, one can see
that the enzymatic activities did not change significantly.
These results indicate that the terminal morpholine
group on the side chain interacted more effectively with
the solvent front16 than the other side chains we intro-
duced. Compounds 45a–c and 46a–c were prepared to
determine if this trend would continue with the analo-
gous 14-membered ring macrocyclic ureas. The excellent
enzymatic assay results of compounds 45a–c and 46a–c
confirmed this hypothesis.
The enzymatic activities of compounds 48f, 48g, 48i, and
48j are better than that of compound 14. However, the
acetamidyl, bromo, chloro, and methyl groups are larger
than the hydroxyl group. It may be interesting to pre-
pare more macrocyclic urea compounds with larger
groups at this position to more fully develop and under-
stand the SAR of these compounds.
A total of 29 compounds were further evaluated in the
MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy-
phenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) cell
proliferation assay and FACS (fluorescence-activated

G. Li et al. / Bioorg. Med. Chem. Lett. 17 (2007) 6499–6504
6503
cell sorting) analysis.6,14–17,21 The MTS assay measures
the amount of surviving cells as an assessment of cyto-
toxicity. FACS analysis measures abrogation of the
G2 checkpoint as an indicator of Chk1-based cellular
mechanism for the compounds. A Chk1 mechanism-
based compound is expected to have little single agent
activity when administered alone in MTS and FACS.
Preferably, the IC50 values should be higher than the
maximum concentration of 59.29 and 10.00 lM used
for MTS and FACS analysis, respectively. In combina-
tion with DNA damaging agents such as doxorubicin
(Dox), the Chk1 inhibitor should significantly enhance
cytotoxicity.
have very good enzymatic activity, however, 12 com-
pounds showed no combination activity in the MTS
cell proliferation assay (>5.93 lM) and 7 compounds
showed no combination activity in the FACS assay
(>10.00 lM).
In Table 2, 12 compounds showed single agent activity
in the MTS assay (<59.29 lM); while no compound
showed single agent activity in the FACS assay (all
>10.00 lM). Since MTS measures cell survival, com-
pounds that had single agent activity could inhibit cell
growth without alteration of the cell cycle profiles. The
fact that most of the compounds were weak in MTS
and inactive in FACS indicated that they lacked non-
mechanism-based cellular profiles, which was consistent
with the Chk1 siRNA data.6
Table 2 shows the results of the above two cellular as-
says, along with the enzymatic assay data (all presented
as IC50 values). Because of compound-to-compound
variabilities concerning such factors as cell permeability,
compounds with good enzymatic activity do not always
have good cellular activity. In Table 2, all 29 compounds
Generally speaking, the two cellular assays correlate
well with each other. Among all 29 compounds, six com-
pounds (48a, 49a, 49b, 49g, 49h, and 67c) did not show
Table 2. Results of the MTS cell proliferation and FACS analysis
a
b
Compound
Chk1 IC50 (nM)
MTS EC50 (lM)
Compound alone
Compound/Doxc
FACS EC50 (lM)
Compound alone
Compound/Doxd
14
15
34
15
4
>59.29
30.38
7.56
3.31
NV
>10.00
>10.00
NDe
0.54
6.06
45b
45df
46df
48a
48b
48c
48e
48f
48g
48h
48if
48j
0.50
>5.93
3.08
NDe
2.19
5
>59.29
>59.29
>59.29
>59.29
>59.29
5.27
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
>10.00
6
1.27
37
19
5
>5.93
NV
4.25
>10.00
2.71
1.18
5
3.04
5.92
1.14
3.43
16
12
12
10
15
25
55
7
39.91
29.37
2.86
3.91
1.05
1.93
39.95
11.90
2.60
3.13
4.53
0.96
>59.29
>59.29
>59.29
4.03
49a
49b
49c
49e
49g
49h
49if
65a
65b
65c
66b
66c
67a
67b
67c
>5.93
>5.93
3.99
>10.00
>10.00
>10.00
1.23
3
8.87
52.77
0.28
12
16
11
97
91
19
69
13
39
24
11
>5.93
>5.93
3.04
>10.00
>10.00
2.65
>59.29
57.57
NV
>5.93
3.13
5.54
3.12
3.12
>59.29
30.86
1.84
1.01
>59.29
>59.29
>59.29
>59.29
>59.29
>5.93
>5.53
>5.93
5.37
1.93
4.48
2.29
>10.00
>5.93
a Tested using HeLa cells, a p53-deficient human cervical cancer cell line.
b Tested using NCI-H1299 cells, a human lung cancer cell line.
c Calculated from the percentages of inhibition by varying concentration of the test compounds above the background inhibition by 100 nM of
doxorubicin, a topoisomerase II inhibitor in clinical use known to confer G2/M checkpoint arrest at this concentration in HeLa cells. The ability of
the compound to sensitize HeLa cells is represented by the ratio of the EC50 values of the compound alone and the compound with 100 nM
doxorubicin.
d Compounds alone (10 lM) caused no alternation in cell cycle distribution in comparison to the DMSO control. Doxorubicin at 500 nM led to a
dramatic shift of cell distribution in comparison with the DMSO control, with most of the cell population in the G2/M phase and a very low
population of apoptotic cells. Increasing the concentration of the compounds such as 14, 46d, and 48j significantly reduced the G2/M population
and simultaneously increased apoptotic cells, which is consistent with the abrogation of the G2 checkpoint arrest and induction of apoptosis.
e Not determined.
f See Ref. 22.

6504
G. Li et al. / Bioorg. Med. Chem. Lett. 17 (2007) 6499–6504
10. Roberge, M.; Berlinck, R. G.; Xu, L.; Anderson, H. J.;
Lim, L. Y.; Curman, D.; Stringer, C. M.; Friend, S. H.;
Davies, P.; Vincent, I.; Haggarty, S. J.; Kelly, M. T.;
Britton, R.; Piers, E.; Andersen, R. J. Cancer Res. 1998,
58, 5701.
11. Eastman, A.; Kohn, E. A.; Brown, M. K.; Rothman, J.;
Livingstone, M.; Blank, D. H.; Gribble, G. W. Mol.
Cancer Ther. 2002, 1, 1067.
any activity in either of the two cellular assays. Fourteen
compounds (14, 46d, 48c, 48e, 48f, 48g, 48h, 48i, 48j, 49i,
65b, 65c, and 67b) showed activity in both cellular as-
says. Among these 14 compounds, compounds 14, 46d,
48c, 48j, 65b, and 67b showed the greatest inhibitory
activity. The most active compounds in the cellular as-
says were compounds 14, 46d, and 48j.
12. Kohn, E. A.; Yoo, C. J.; Eastman, A. Cancer Res. 2003,
63, 31.
In summary, we have modified successfully the C5 posi-
tion of the benzene ring of the macrocyclic urea core.
Forty new macrocyclic urea compounds were prepared
and 29 of these compounds showed excellent Chk1 enzy-
matic activity (<20 nM). Compounds 14, 46d, and 48j
showed the best overall results in all three assays with
IC50’s of 34, 6, and 15 nM; ratios of single agent to com-
bination activity of >59.29 lM/3.31 lM, >59.29 lM/
3.08 lM, and >59.29 lM/3.13 lM in the MTS assay;
and ratios of single agent to combination activity of
>10.00 lM/0.54 lM, >10.00 lM/1.27 lM, and >10.00 lM/
0.96 lM in the FACS assay, respectively. Further inves-
tigation is needed to optimize the design of these Chk1
inhibitors.
13. Sausville, E. A.; Arbuck, S. G.; Messmann, R.; Headlee,
D.; Bauer, K. S.; Lush, R. D.; Murgo, A.; Figg, W. D.;
Lahusen, T.; Jaken, S.; Jing, X.-X.; Roberge, M.; Fuse, E.;
Kuwabara, T.; Senderowicz, A. M. J. Clin. Oncol. 2001,
19, 2319.
14. Li, G.; Li, Q.; Li, T.; Lin, N.-H.; Mantei, R. A.; Sham, H.
L.; Wang, G.T.U.S. Patent 7,056,925, 2006.
15. Wang, G. T.; Li, G.; Mantei, R. A.; Chen, Z.; Kovar, P.;
Gu, W.; Xiao, Z.; Zhang, H.; Sham, H. L.; Sowin, T. J.;
Rosenberg, S. H.; Lin, N.-H. J. Med. Chem. 2005, 48,
3118.
16. Li, G.; Hasvold, L. A.; Tao, Z.-F.; Wang, G. T.;
Gwaltney, S. L.; Patel, J.; Kovar, P.; Credo, R. B.; Chen,
Z.; Zhang, H.; Park, C.; Sham, H. L.; Sowin, T.;
Rosenberg, S. H.; Lin, N.-H. Bioorg. Med. Chem. Lett.
2006, 16, 2293.
References and notes
17. Chen, Z.; Xiao, Z.; Gu, W.-Z.; Xue, J.; Bui, M.; Kovar, P.;
Li, G.; Wang, G.; Tao, Z.-F.; Tong, Y.; Lin, N.-H.; Sham,
H. L.; Wang, J. Y.; Sowin, T. J.; Rosenberg, S. H.; Zhang,
H. Y. Int. J. Cancer 2006, 119, 2784.
18. Keegan, K.; Kesicki, E. A.; Gaudino, J. J.; Cook, A. W.;
Cowen, S. D.; Gurgess, L. E. WO 02/070494, 2002.
19. Boyle, R. G.; Imogai, H. J.; Cherry, D. WO 03/101444,
2003.
1. Zhou, B. B.; Bartek, J. Nat. Rev. Cancer 2004, 4, 1.
2. Kastan, M. B.; Onyekwere, O.; Sidransky, D.; Vogelstein,
B.; Craig, R. W. Cancer Res. 1991, 51, 6304.
3. Li, Q.; Zhu, G.-D. Curr. Top. Med. Chem. 2002, 2, 939.
4. Greenblatt, M. S.; Bennett, W. P.; Hollstein, M.; Harris,
C. C. Cancer Res. 1994, 54, 4855.
5. Powell, S. N.; DeFrank, J. S.; Connell, P.; Eogan, M.;
Preffer, F.; Domkowski, D.; Tang, W.; Friend, S. Cancer
Res. 1995, 55, 1643.
6. Xiao, Z.; Chen, Z.; Gunasekera, A.; Sowin, T. J.;
Rosenberg, S. H.; Fesik, S.; Zhang, H. J. Biol. Chem.
2003, 278, 21767.
20. Santora, V.; Askew, B.; Ghose, A.; Hague, A.; Kim, T. S.;
Laber, E.; Li, A.; Lian, B.; Liu, G.; Norman, M.H.; Smith,
L.; Tasker, A.; Tegley, C.; Yang, K. WO 02/14311, 2002.
21. Lin, N.-H.; Li, G.; Przytulinska, M. K.; Sowin, T. J.;
Sullivan, G. M.; Tao, Z.-F.; Tong, Y.; Wang, L.U.S.
Patent 7,163,939, 2007.
7. Kawabe, T. Mol. Cancer Ther. 2004, 3, 513.
8. Bunch, R. T.; Eastman, A. Clin. Cancer Res. 1996, 2, 791.
9. Jackson, J. R.; Gilmartin, A.; Imburgia, C.; Winkler, J.
D.; Marshall, L. A.; Roshak, A. Cancer Res. 2000, 60, 566.
22. Tao, Z.-F.; Wang, L.; Stewart, K. D.; Chen, Z.; Gu, W.;
Bui, M.-H.; Merta, P.; Zhang, H.; Kovar, P.; Johnson,
E.; Park, C.; Judge, R.; Rosenberg, S. H.; Sowin, T.; Lin,
N.-H. J. Med. Chem. 2007, 50, 1514.