Extract
Note: Please read the complete
full text with Figures and Tables at
Introduction
Protein tyrosine kinases (PTK) such as epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR),
vascular endothelial growth factor receptor (VEGFR), and platelet-derived growth factor receptor (PDGFR) play important
roles in many of the signal transduction processes that control cell growth, differentiation, mitosis and
apopto-sis[1_3]. EGFR, identified as a PTK in the 1980s, is activated by the binding of its ligands (EGF or
TGF)[4] Mistakenly regulated activity or
overexpression of the receptor have been demonstrated to be related to many human cancers such as breast and liver
cancers[5_8], indicating that EGFR is an attractive target for antitumor drug
discovery[9_13]. In recent years, a large structural variety
of compounds, such as
4-anilinoquinazolines[14],
4-anilinopyrazolo[3,4-d]pyrimidines
[15],
4-anilinoquinoline-3-carbonitriles[16],
7,4-anilinopyrazolo- and
4-anilinopyrrolo-quinazolines[17], were reported as EGFR tyrosine kinase inhibitors. Figure
1includes some representative inhibitors of
EGFR,VEGFR, PDGFR and FGFR which are currently approved drugs or are being
clinical trial.
The indolin-2-one core is a well-known pharmacophore for developing PTK inhibitors (Figure 2). Sun
et al[18,19] developed an extensive structure-activity relationship for the indolin-2-one analogs, suggesting that the inhibitory activity and
selectivity of these compounds against particular PTK depends on the substituents of the indolin-2-one core, especially on
the C-3 position. 3-Substituted indolin-2-ones adopting the Z configuration
(R1 is substituted by pyrrol-2-yls or thien-2-yls)
are potent and selective inhibitors of the FGF tyrosine
kinase[18]. However, compounds with the E configuration
(R1 is substituted by benzylidenyl) show fairly good potency in inhibiting EGFR tyrosine
kinase[19]. The X-ray crystal structures
of the FGFR tyrosine kinase in complex with 3-{[3-(2-carboxyethyl)-4-methylpyrrol-2-yl]methylene}-2-indolinone
(SU5402)[20] revealed that the indolin-2-one core of SU5402 occupied the adenine pocket of the ATP binding site of the tyrosine kinase,
and the substituted groups at the R1 position bound to the hydrophobic pocket of the ATP binding site (Figure 2). SU5402
with the
Z configuration is a selective inhibitor of FGFR and VEGFR. What caught our attention in particular was the biological
activity of E-3-substituted indolin-2-one derivatives. We introduce a
b-pyrrole group into the 3-position of indolin-2-ones to
see whether it would enhance the interaction between indolin-2-one compounds and tyrosine kinase and increase antitumor
activity. Accordingly, a novel class of 3-pyrrole, 5-substituted indolin-2-one derivatives (1a_t) have been synthesized, and
their inhibitory activities against EGFR, FGFR, VEGFR and PDGFR were determined. Significantly, compounds 1g and 1h
showed promising antiproliferative effects in tumor cell lines.
Materials and methods
Chemistry
Design of analogues of
compounds The inhibitory activity and selectivity of indolin-2-one analogs against particular
PTK depends on the C-3 substituted groups of the indolin-2-one core. SU5402 is a selective inhibitor of FGFR and VEGFR,
and bears a Z configuration. Based on the scaffold of SU5402, 20 new analogues (1a_t) (Table 1) were designed and
synthesized. Keeping the key groups of SU5402,
3-substituted indolin-2-one core and pyrrole ring, we used various steric, electronic, and hydrophobic groups to substitute
position 5 of the indolin-2-one core, changed the substituted position between the pyrrole ring and the indolin-2-one core,
and introduced a b-pyrrole group into the 3-position of the indolin-2-ones (Table 1).
Synthetic procedures Figure 3 depicts the sequence of reactions that led to the preparation of compounds 1a_t
using acetonedicarboxylates as the starting materials. In general, dimethyl-1,3-acetonedicarboxylate and
diethyl-1,3-acetonedicarboxylate reacted with
t-butyl acetoacetate by classic Knorr synthesis to produce 2a_b,
respectively[21]. Compounds 2a_b were hydrogenated, decarboxylated and treated by Vilsmeier formylation condition, giving the key
intermediates 5a_d. Indolin-2-ones were commercially available. 5-Bromoindolin-2-one (6) and 5-nitroindolin-2-one (7) were prepared
by bromination and nitration of
indolin-2-one[18], respectively.
5-Carboxyindolin-2-one[18] (8) was
afforded by hydrolysis of 5-chloroacetylindolin-2-one, which
was prepared by chloroacetylation of indolin-2-one. 5-(amino-
sulfonyl) and the other 5-(substituted aminosulfonyl)-indolin-2-ones (compounds 10a_i) were obtained by amidation of
5-(chlorosulfonyl)indolin-2-one (9), which was prepared by sulfonylation of indolin-2-one with chloro-sulfonic acid.
Compounds 1a_t were synthesized by condensing pyrrole aldehydes (5a_d) and 5-substituted indolin-2-ones in the presence of
piperidine.
Biology assay
Tyrosine kinase assays by ELISA The tyrosine kinase assays were measured using the ELISA assay as previously
described[22]. The tyrosine kinase activities of the purified EGFR, FGFR, VEGFR and PDGFR were determined in 96-well ELISA
plates pre-coated with 20 µg/mL Poly(Glu,
Tyr)4:1 (Sigma Chemical Co, St Louis, MO, USA). Briefly, 85µL of 8 µmol/L ATP
solution diluted in kinase reaction buffer solution (50 mmol/L HEPES, pH 7.4, 20 mmol/L
MgCl2, 0.1 mmol/L MnCl2, 0.2
mmol/L Na3VO4), 1 mmol/L dithiothreitol (DTT) was added to each well. Then, 10 µL of diluted compounds were added to each
reaction well at varying concen-trations. 0.1% DMSO
(v/v) was used as the negative control. Experiments at each
concentration were performed in triplicate. The kinase reaction was initiated by the addition of purified tyrosine kinase proteins
diluted in 10 µL of kinase reaction buffer solution. After incubation for 60 min at 37 °C, the plate was washed 3 times with
phosphate buffered saline (PBS) containing 0.1% Tween 20 (T-PBS). Next, 100 µL of antiphosphotyrosine (PY99) antibody
(1:500 dilution) diluted in T-PBS containing 5 mg/mL bovine serum albumin (BSA) was added. After 30 min incubation at 37
°C, the plate was washed 3 times. Goat anti-mouse IgG horseradish peroxidase (100 µL, 1:2000 dilution) diluted in T-PBS
containing 5 mg/mL BSA was added. The plate was reincubated at 37 °C
for 30 min and washed as before. Finally, 100 µL
solution (0.03% H2O2, 2 mg/mL o-phenylenediamine in citrate buffer 0.1 mol/L, pH 5.5) was added and incubated at room
temperature until color emerged. The reaction was terminated by the addition of 100 µL of
H2SO4 (2 mol/L), and
A492 was measured using a multi-well spectrophotometer
(VERSAmaxTM, Charlot-tesville, VA, USA). The inhibition rate (IR; %) was
calculated with Equation 1.
IR=(1_[A492/A492
(control)])×100% (1)
Compounds PD135035, SU5402, SU5416 and TKI30 were used as positive controls for the EGFR, FGFR, VEGFR and
PDGFR kinase, respectively.
Cell growth inhibition assay by sulforhodamine B
(SRB) Three human carcinoma cell lines, A-431 (epidermoid
carcinoma), A-549 (lung carcinoma) and MDA-MB-468 (breast carcinoma), obtained from American Type Culture Collection
(Rockville, MD, USA), were used for the cell proliferation assay. Cells were maintained in RPMI-1640
medium supplemented with 10% (v/v) fetal bovine serum, 2
mmol/L glutamine, 100 U/mL penicillin, and 100 µg/mL streptomycin (Gibco, Grand Island,
NY, USA) in a highly humidified atmosphere of 95% air with 5%
CO2 at 37 °C. The growth inhibition was analyzed by the
sulforhodamine B (SRB; Sigma, USA)
assay[23]. Briefly, the cells were seeded at 6000
cells/well in 96-well plates (Falcon, Oxnard, CA, USA), and allowed to attach overnight. The cells were treated in
triplicate with grade concentrations of compounds at 37
°C for 72 h. Then they were fixed with 10% trichloroacetic acid and incubated for 60 min at 4 °C. The plates were then washed
and dried. SRB solution (0.4% w/v in 1% acetic acid) was added and the culture was incubated for an additional 15 min. After
the plates were washed and dried, the bound stain was solubilized with Tris buffer, and the optical densities were read on the
plate reader (model VERSAmax, Molecular Devices, USA) at 515 nm
(A515). The growth inhibitory rate (GIR) of treated cells
was calculated by Equation 1.
The results were also expressed as
IC50 (the compound concentration required for 50% growth inhibition of tumor cells),
which was calculated by the Logit method. The mean
IC50 was determined from the results of 3 independent tests.
Cell growth inhibition assay by
MTT The cancer cell line Autosomal Dominant Polycystic Kidney disease (ADPKD),
which was provided by Shanghai Changzheng Hospital (Shanghai, China), was used for the cell proliferation assay. The cell
was cultivated in DMEM/F12 (Gibco, USA) supplemented with 100 mL/L fetal calf serum (FCS; Sijiqing Company, Hangzhou,
China), penicillin (100 µg/mL) and streptomycin (100 µg/mL) in a humidified atmosphere of 5%
CO2 at 37 °C. rhEGF was obtained from Calbiochem Company (Darmstadt, Germany).
The growth inhibition was evaluated by the modified MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide)
assay[24]. Briefly, the cells were seeded at
1×104 cells/well in 96-well plates (Falcon, USA), and incubated for 24 h in 100 mL
culture media with 10% FCS. Then the media were replaced by serum-free medium. After 24 h, the media were placed in
triplicate with grade concentrations of compounds, 1 ng/mL hEGF and 2% FCS medium at 37 °C for 72 h. Then the cells were
treated with MTT (Sigma, USA) 10 µL (5 g/L) for 4 h. After the removal of the supernatant, the purple-blue sediment dissolved
in 100 µL/well DMSO, and the optical densities were read on a multi-well scanning spectrophotometer (Labsystems Dragon,
Finland) at 490 nm (A490). The GIR of the treated cells was calculated by Equation 1.
The results were also expressed as
IC50 (the compound concentration required for 50% growth inhibition of tumor cells),
which was fitted by using the sigmoidal fitting model by the Origin7.0
software[25]. The mean IC50 was determined from the
results of 3 independent tests.
Molecular modeling The crystal structures of the kinase domain of EGFR in complex with its inhibitor Tarceva (AQ4774,
PDB entry 1M17)[26] was acquired from the Brook-haven Protein Database (PDB) (http://www.pdb.org). The missing atoms
and residues were reconstructed using Sybyl
6.8[27]. Kollman-united-atom
charges[28],and Gasteiger-Marsili
charges[29] were assigned to the protein and inhibitor, respec-tively.
To find the binding mode of SU5402 and compound
1 with EGFR, the advanced docking program AutoDock
3.0.3[30,31] was used to automatically dock the inhibitors to the binding site of EGFR. The Lamarckian genetic algorithm
(LGA)[31] was applied to identify the binding orientation and conformation of these 2 inhibitors interacting with EGFR. A Solis and
Wets local search performed the energy minimization on a user-specified proportion of the population. The number of
generation, energy evaluation, and docking runs were set to
3.7×105, 1.5×106, and 20, respectively. The docked
conformations of the inhibitor were generated after a reasonable number of evaluations. Typically, 5 binding energy terms used in
current version of AutoDock 3.0[30,31] were
included in the scoring function: the van der Waals interaction represented as a Lennard-Jones 12_6 dispersion/repulsion
term; the hydrogen bonding represented as a directional 12_10 term; the Coulombic electrostatic potential; desolvation upon
binding; and the hydrophobic effect (solvent entropy changes at solute-solvent interfaces).
The whole docking operation in this study could be stated as follows: first, the binding site of EGFR was checked for polar
hydrogen and assigned for partial atomic charges, then a PDBQ file was created, and then atomic solvation parameters were
assigned for the protein. Meanwhile, some of the torsion angles of the inhibitor that would be explored during the molecular
docking stage were defined, allowing the conformation search for the inhibitors during the docking process. Second, the grid
map with 80×80×80 points and a spacing of 0.375Å was calculated using the AutoGrid
program[29] to evaluate the binding energies between the inhibitors and the protein. Third, some important parameters for LGA calculations were reasonably set,
not only the atom types, but also the generations and the number of runs for the LGA algorithm were edited and properly
assigned according to the requirement of the Amber force
field[32,33]. The maximum number of generations, energy evaluations,
and docking runs were set to
3.0×105, 1.5×106, and 30, respectively. Finally, the inhibitor-protein complex derived from
docking was selected according to the criterion of interaction energy combined with geometrical matching quality.
Results
Analogue synthesis and structural
characteristics In total, 20 new compounds (1a_t) were designed and synthe-sized,
and their chemical structures are shown in Table 1. These compounds were synthesized through the routes outlined in Figure
3, and the details for synthetic procedures and structural characterizations are described in the Discussion section.
Only one isomer of the product was detected in thin layer chromatography (TLC) analysis and
1H NMR spectrum. The chemical shifts of the vinyl proton in documented 3-substituted indolin-2-ones were around 7.85_8.53 ppm for the Z isomer,
and 7.45_7.84 ppm for the E isomer[18]. The chemical shifts of the vinyl protons of compounds 1a_t are consistent with that
of the related E isomers reported[18]. The
13C-NMR chemical shifts of the b-carbon of
a, b-unsaturated carbonyl compounds 1d and 1e are 147 ppm and 141 ppm, respectively.
The absolute configuration of 1a was finally confirmed by X-ray structural analysis with a yellow needle single crystal,
obtained by slow evaporation of a dilute solution in
EtOH/H2O (40:1). The X-ray crystal structure of 1a is shown in Figure 4A.
The pyrrole ring and the carbonyl O of the indolin-2-one are at the opposite sides of the double bond, indicating that 1a is E
isomeric. The superposition of the AutoDock predicting conformation of 1a with the X-ray structure is shown in Figure 4B.
The root mean square deviation between these 2 conformations is ~0.386Å, and the major deviation is from the flexible moiety
_CH2CO2CH2CH3
, indicating that the bioactive conformation of 1a is similar to its crystal structure.
Biological activities The enzyme assay data are summarized in Table 1. Disappointingly, most compounds only
displayed low to moderate inhibition activity against EGFR, FGFR, VEGFR and PDGFR at the concentration of 10 µmol/L. To
some extent, compounds 1a, 1b, 1c, 1g, and 1h exhibited a better ability to inhibit the EGFR and VEGFR kinase (percent
inhibition at 10 µmol/L >20.0%) than the FGFR and PDGFR kinase. However, the cellular assay turned out more encouraging
(Table 2). Four human carcinoma cell lines of A-431, A-549, MDA-MB-468 and ADPKD were chosen for the cell proliferation
assay. The results indicate that compounds 1d, 1g and 1h show promising anti-proliferation activities for A-431, A-549 and
MDA-MB-468 (percent inhibition rates at 10 µmol/L>50%; Table 2). It is remarkable that 1d and 1e show fairly good activity
against ADPKD (IC50=0.1 and 3.7 µmol/L, respectively). Compounds 1d and 1g substituted with
_CH2CO2Me and methyl groups in the 3'-C position of the pyrrole ring are much more potent than compounds 1b and 1j substituted with
_CH2CO2Et. The bromination or nitration at the C-5 position of the indolin-2-one core increased the potency (1d>1c, 1g>1e). The
inconsistency between the enzyme activity and the cellular efficiency could imply that the new type of indolin-2-one
compounds might inhibit multiple key proteins involved in the EGFR and VEGFR signaling pathways, not only targeting the
tyrosine kinase, thus leading to the significant antiproliferation effect against EGFR- dependent tumor cell lines, which is
highly relevant to the overexpression of EGFR or VEGFR kinase. The definite mechanism is still under study.
Molecular modeling We docked the structures of SU5402 and compound 1a into the active site of EGFR-TK by using
AutoDock 3.0.3[30,31]. The predicted bioactive conformations of SU5402 and compound 1a are shown in Figure 5. The ATP
binding pocket of EGFR consists of Thr766, Gln767, Leu768, Met769, Gly772, Thr830, Asp831, Val702, Lys721, Ala719, Glu738,
and Met742[5]. This binding pocket can be divided into 3 regions, including 2 hydrophobic regions and an adenine
region[5]. The adenine region mainly comprises Gln767 and
Met769[5]. Hydrophobic region I shaped by Ala719_Lys721,
Leu764_Thr766, Thr830 and Asp831 is located deep inside the ATP binding
pocket[5]. Hydrophobic region II mainly comprises Leu694
and Gly772[5]. SU5402 formed 1 hydrogen bond with Thr766, and 6 hydrophobic interactions with Leu694, Val702, Ala719,
Lys721, Leu830 and Asp831 (Figure 5A). The intramolecular hydrogen bonding between the N atom of the pyrrole ring and
the carboxyl O atom of the indolin-2-one core in SU5402 is responsible for the Z isomeric
form[18] (Figure 5A). When changing the
a-pyrrole ring to a b-pyrrole ring, the distance between these 2 atoms is lengthened, and the introduction of a methyl
group in the 5'-position of the pyrrole ring avoids the intramolecular hydrogen bond formation. Figure 5B shows the
interaction model of compound 1a and EGFR. The indolin-2-one core of compound 1a occupies the adenine pocket of EGFR,
and the pyrrole moiety lies in the hydrophobic region. Compound 1a forms 3 hydrogen bonds with Met769 and Thr830, and
8 hydrophobic interactions with Leu694, Phe699, Val702, Ala719, Ile720, Lys721, Arg817 and Leu820. This binding model is
similar to that of Tarceva and EGFR[26]. The quinazoline and anilino moieties of Tarceva also occupied
the adenine pocket and the hydrophobic region,
respectively[28]. There are more hydrogen bonds and hydrophobic interaction pairs between 1a and
EGFR than with SU5402 and EGFR.
Discussion
In summary, by replacing the a-pyrrole ring at the 3-
position of the indolin-2-one core of Z-SU5402 with a
b-pyrrole ring, and introducing a methyl group at the 5'-position of a
pyrrole ring, we successfully designed and synthesized a series of E-3-substituted indolin-2-ones. Biological assay
indicated that 4 compounds (1d, 1e, 1g, and 1h) exhibited promising inhibitory activity toward the A-549, MDA-MB-468, and
ADPKD cell lines. Compounds 1g and 1h provide a promising new template for further development of antitumor agents.
Appendix
The reagents (chemicals) were purchased from Lancaster (Morecambe, England), Acros (Geel, Belgium) and Shanghai Chemical Reagent
Company (Shanghai, China), and were used without
further purification. Analytical TLC was conducted with HSGF 254
(0.15_0.2 mm thickness; Yantai Huiyou Company, Yantai, China). Yields were not optimized. Melting points were measured in capillary tubes on a SGW X-4 melting
point apparatus (Shanghai Precision & Scientific Instrument Co, LTD, Shanghai, China) without correction. Nuclear magnetic resonance
(NMR) spectra were obtained on a Brucker AMX-400 NMR (TMS as IS; Brucker, Fällanden, Switzerland). Chemical shifts are reported in parts
per million (ppm, d) downfield from tetramethylsilane. Proton coupling patterns were described as singlet (s), doublet (d), triplet (t), quartet
(q), multiplet (m), and broad (br). Low- and high-resolution mass spectra were given with electric, electro-spray, and matrix-assisted laser
desorption ionization from Finnigan MAT-95 spectrometer (Finnigan, Santa Clara, CA, USA).
General procedures for preparations of 2(a_b) are
described as those for 4-benzyl 2-ethyl
3-(2-ethoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2,4-dicarboxylate
(2a) Sodium nitrite (1.38 g, 20 mmol) in water (20 mL) was slowly added while stirring diethyl
acetone-1,3-dicarboxylate (4.04 g, 20 mmol) in acetic acid (100 mL) at 4_8 °C. After 15 min, benzyl acetoacetate (3.84 g, 20 mmol) and anhydrous sodium
acetate (2.50 g, 36 mmol) were added followed by a mixture of zinc dust (3.50 g, 5.3 mmol) and sodium acetate (1.00 g, 12 mmol) during a 5
min period. To keep the product in the solution, acetic acid (10 mL) was added, and the mixture was refluxed for 3 h and poured into water.
The precipitate obtained was filtered, washed with acetic acid (10 mL) and dried to afford 2a (3.21 g, 43%) as a
white solid: mp 149 °C; 1H NMR (400 MHz,
CDCl3): d9.0 (br, 1H), 7.3_7.4 (m, 5H), 5.25 (s, 2H), 4.3
(q, 2H), 4.2 (s, 2H), 4.05 (q, 2H), 2.5 (s, 3H), 1.35 (t, 3H) and
1.2 (t, 3H).
4-benzyl 2-methyl
3-(2-methoxy-2-oxoethyl)-5-methyl-1H- pyrrole-2,4 -dicarboxylate
(2b) was recrystallized from ethanol, yield 41%: mp 148 °C;
1H NMR (400 MHz, CDCl3):
d9.0 (br, 1H), 7.3_7.4 (m, 5H,), 5.25 (s, 2H), 4.2 (s, 2H), 2.5 (s, 3H), 1.35 (s, 3H) and
1.2 (s, 3H).
General procedures for preparation of 3(a_b) are described as those for
4-(2-ethoxy-2-oxoethyl)-5-(ethoxycar-bonyl)-2-methyl-1
H-pyrrole-3-carboxylic acid (3a) Compound 2a (3.21 g, 8.6 mmol) was dissolved in methanol and hydrogenated by 1.2 g of 10%
palladium on carbon for 1.5 h at room temperature. The catalyst was removed by filtration and washed with methanol, and the filtrates were
combined and concentrated to give 3a (2.19 g, 87%) as a pale solid: mp 249 ºC;
1H NMR (400 MHz, CDCl3):
d9.6 (br, 1H), 4.3 (q, 2H), 4.2 (q, 2H), 3.80 (s, 2H), 2.3 (s, 3H,), 1.3 (t, 3H) and
1.2 (t, 3H).
4-(2-methoxy-2-oxoethyl)-5-(methoxycarbonyl)-2-methyl-1
H-pyrrole-3-carboxylic acid (3b) was recrystallized from ethanol,
yield 41%: mp 243 °C; 1H NMR (400 MHz,
CDCl3): d9.6 (br, 1H), 3.80 (s, 2H), 2.3 (s, 3H), 1.3 (s, 3H) and 1.2 (s, 3H).
General procedures for preparations of 4(a_b) are
described as those for ethyl
3-(2-ethoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2-
carboxylate (4a) A solution of the crude acid 3a (2.19 g, 7.4 mmol) and sodium bicarbonate (392 mg, 4.6 mmol) in water (10 mL) was added
with constant stirring to a solution of iodine (1.49 g, 5.8 mmol) and potassium iodide (1.22 g, 7.4 mmol) in water (10 mL). The mixture was
heated at 90 °C during a 1 h period, and then cooled; the solid was filtered, dried and crystallized from methanol. The crude product was
dissolved in methanol (10 mL) and heated to reflux. A solution of potassium iodide (1.52 g, 9.15 mmol) in water (10 mL) was added in a 5 min
period. Thirty-six percent of HCl (13 mL) and sodium hydrosulfite (174 mg, 1 mmol) was then added. After 15 min, the mixture was cooled
and extracted with EtOAc. The organic layer was washed, dried, filtered and condensed to afford 4a (1.53 g, 87%): mp 251 °C;
1H NMR (400 MHz, CDCl3): d 9.1 (br, 1H), 5.98 (s, 1H), 4.3 (q, 2H), 4.2 (q, 2H), 3.80 (s, 2H), 2.3 (s, 3H), 1.3 (t, 3H) and 1.2 (t, 3H).
Methyl 3-(2-methoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2-
carboxylate (4b) was recrystallized from enthanol, yield 89%: mp 238 °C;
1H NMR (400 MHz, DMSO): d5.98 (br, 1H), 3.80 (s, 2H),
2.3 (s, 3H), 1.3(s, 3H) and 1.2 (s, 3H).
General procedures for preparations of 5(a_d) are
described as those for ethyl
3-(2-ethoxy-2-oxoethyl)-4-formyl-5-methyl-1H
-pyrrole-2-carboxylate (5a) 4a 1.53 g, 6.4 mmol was dissolved in dimethylforamide (10 mL) and treated at 0 °C with phosphorus
oxychloride (4.5 mL) at 0 °C , and the mixture was heated on a steam bath for 20 min. The mixture was cooled and poured into water (20 mL);
ammonium hydroxide (50 mL) was added, and the mixture was immediately filtered to remove dark-colored precipitates. The solids were
thoroughly washed with water, and the combined aqueous portion was extracted with ether (20 mL). Evaporation of the ether solution yielded
the crude aldehyde, which was recrystallized from ethanol to give 5a (1.43 g, 84%) as
pale-yellow needles: mp 122 °C; 1H NMR (400 MHz,
CDCl3): d 10.0 (s, 1H), 9.1 (br, 1H), 4.3 (q, 2H), 4.2 (q+s, 4H), 3.80 (s, 2H), 2.3 (s, 3H), 1.3 ( t, 3H) and 1.2 (t, 3H).
Methyl
3-(2-methoxy-2-oxoethyl)-4-formyl-5-methyl-1H
-pyrrole-2-carboxylate (5b) was recrystallized from ethanol, yield 87%: mp132
°C; 1H NMR (400 MHz, CDCl3
): d 10.0 (s, 1H), 9.1 (br, 1H), 4.3 (q, 2H), 2.3 (s, 3H), 1.3 (t, 3H) and 1.2 (t, 3H).
Ethyl
4-formyl-3,5-dimethyl-1H-pyrrole-2-carboxylate (5c) was prepared by using ethyl
3,5-dimethyl-1H-pyrrole-2-carboxylate[35]
as starting materials, and recrystallized from ethanol-water, yield 82%: mp182 °C;
1H NMR (400 MHz, CDCl3): d 10.0 (s, 1H), 9.76(s,1H),
4.29(q, 2H), 2.30 (s, 3H), 2.24 (s, 3H) and 1.35 (t, 3H).
Methyl
4-formyl-3,5-dimethyl-1H-pyrrole-2-carboxylate (5d) was prepared by using methyl
3,5-dimethyl-1H-pyrrole-2-carboxylate[36]
as starting materials, and recrystallized from ethanol-water,
yield 89%: mp185 °C; 1H NMR (400 MHz,
CDCl3): d 9.76 (s, 1H), 3.82 (s, 3H),
2.30 (s, 3H) and 2.24 (s, 3H).
General procedures for preparations of 10(a_i) are
described as those for 5-aminosulfonyl-indolin-2-one
(10a) Chloro-
sulfonic acid (27 mL) was slowly added to indolin-2-one (13.3 g, 100 mmol). The reaction temperature was maintained below 30 °C during the
addition. After the addition, the reaction mixture was stirred at room temperature for 1.5 h, and stirred at 68 °C for 1 h, cooled, and poured
into water. The precipitate was washed with water and dried in a vacuum oven to give compound 9 (11.0 g, 50%), which was used without
further purification. Compound 9 (2.1 g, 9.1 mmol) was added to 10 mL of ammonium hydroxide in ethanol (10 mL) and stirred at room
temperature overnight. The mixture was concentrated and the solid collected by vacuum filtration to give 10a (0.4 g, 20%) as an off-white
solid: EI-MS m/z 211 (M+_1).
5-methylaminosulfonyl-indolin-2-one (10b) was prepared by using compound 9 and methylamine as starting materials, and recrystallized
from dichloromethane, yield 82%: EI-MS m/z 225
(M+_1).
5-morpholinylaminosulfonyl-indolin-2-one (10c) was prepared by using compound 9 and morpholinylamine as starting materials, and
recrystallized from dichloromethane, yield 90%: EI-MS
m/z 282 (M+).
5-(3-chlorophenylamino)sulfonyl-indolin-2-one (10d) was prepared by using compound 9 and 3-chlorophenylamine as starting materials,
and recrystallized from dichloromethane, yield 72%:
EI-MS m/z 321 (M+).
5-(3-fluorophenyl)aminosulfonyl-indolin-2-one (10e) was prepared by using compound 9 and 3-fluorophenylamine as starting materials,
and recrystallized from dichloromethane, yield 80%:
EI-MS m/z 306 (M+).
5-dimethylaminoaminosulfonyl-indolin-2-one (10f) was prepared by using compound 9 and dimethylamine as starting materials, and
recrystallized from dichloromethane, yield 87%: EI-MS
m/z 240 (M+).
5-(3-fluoro-4-chlorophenyl)aminosulfonyl-indolin-2-one (10g) was prepared by using compound 9 and 3-fluoro-4-chlorophenylamine as
starting materials, and recrystallized from dichloromethane, yield 80%: EI-MS
m/z 340(M+).
5-piperidinylaminosulfonyl-indolin-2-one (10h) was prepared by using compound 9 and piperidinylamine as starting materials, and
recrystallized from dichloromethane, yield 80%: EI-MS
m/z 282 (M+).
5-(3-bromophenyl)aminosulfonyl-indolin-2-one (10i) was prepared by using compound 9 and 3-bromophenylamine as starting materials,
and recrystallized from dichloromethane, yield 80%:
EI-MS m/z 340 (M+).
General procedures for preparations of 1(a_t) are
described as those for (E)-ethyl
3-(2-ethoxy-2-oxoethyl)-5-methyl-4-(indolin-2-one-3-ylidene)methyl)
-1H-pyrrole-2-carboxylate (1a) A reaction mixture of indolin-2-one (50 mg, 0.37 mmol) and 5d
(100 mg, 0.37 mol), and 3 drops of piperidine in ethanol (5 mL) was stirred at 90 °C for 5 h. After the mixture cooled, the precipitate was
filtered, washed with cold ethanol, and dried to afford 1a (105mg, 75%) as a yellow solid: mp 215_217 °C.
1H NMR (400 MHz, CDCl3): d
9.90 (br, 1H), 9.20 (br, 1H), 7.82 (s, 1H), 7.20 (t, 2H), 7.09 (t, 1H), 6.90 (m, 2H), 4.33 (q, 2H), 4.08 (q, 2H), 3.80 (s, 3H), 2.21 (s, 3H), 1.36
(t, 3H) and 1.20 (t, 3H); EI-MS m/z 384
(M+); Found: C,
65.86; H, 5.85; N, 7.33.
C21H22N2O5
: requires C, 65.60; H, 5.90; and N, 7.30%.
Crystallographic data of compound 1a
Single crystal of 1a suitable for X-ray crystal structure analysis was obtained by growth under
slow evaporation at 5 °C from dilute solution in
EtOH/H2O (40:1). Crystal data and structure solutions at T=293(2)°K: orthorhombic,
P212121, a=8.5204(18) Å (7), b=10.488(2)Å, c=
11.933(3)Å, V=1004.9(4)Å3, Z=2,
Dx=1.264 Mg/m3, F(000)=404, l(MoKa)=0.71070Å, µ=0.091
mm_1. The intensity data were collected on
a Bruker Smart APEX CCD diffractometer (USA) with graphite mono-chromated
MoKa radiation and phi and omega scan technique [1a:
2qmax=47.00°]. The structures were solved by direct methods using SHELXS-97 (Goettingen,
Germany)[37] and expanded using Fourier
techniques[38]. The non-hydrogen atoms were refined anisotropically. The final cycle offull-matrix least-squares refinement was based on 6109
(1a) unique reflections and 4417 (1a) variable parameters and converged with unweighted and weighted factors of 1a (R1=0.0749 and
Rw2=0.1625). Neutral atom scattering factors were taken from Cromer and
Waber[39]. Anomalous dispersion effects were included in Fcalc, the values
for Df ' and Df ' were those of Creagh and
McAuley[40], the values for the mass attenuation coefficients were those of Creagh and
Hubbell[41]. All calculations were performed using
SHELXL-97[37]. Their crystal structures have been deposited at the Cambridge Crystallographic Data Centre
and allocated the deposition numbers: CCDC 219645 for 1a.
(E)-ethyl 4-((5-bromo-indolin-2-one-3-ylidene)methyl)-3-(2-ethoxy-2-oxo
ethyl)-5-methyl-1H-pyrrole-2-carboxylate (1b) was
recrystallized from ethanol-water, yield 80%: mp 210_212 °C;
1H NMR (400 MHz, CDCl3): d 7.48 (s, 1H), 7.38 (d, 2H), 6.96 (s, 1H), 6.80 (q, 2H),
4.23 (q, 2H), 3.98 (q, 2H), 3.75 (s, 2H), 2.09 (s, 3H),
1.36 (t, 3H) and 1.20 (t, 3H); EI-MS m/z 460
(M+); Found: C, 54.60; H, 4.21; N, 6.04.
C21H21BrN2O5
: requires C, 54.68; H, 4.29; and N,
6.07%.
(E)-methyl 3-(2-methoxy-2-oxoethyl)-5-methyl-4-((indolin-2-one-3-ylidene)
methyl)-1H-pyrrole-2-carboxylate (1c) was
recrystallized from ethanol-water, yield 91%: mp 215 °C;
1H NMR (400 MHz, CDCl3): d 9.10 (br, 1H), 7.70 (s, 1H), 7.38 (t, 2H), 7.19 (s, 1H), 6.78
(t, 2H), 3.90 (s, 3H), 3.88 (s, 2H), 3.67 (s, 3H) and 2.20 (s, 3H); EI-MS
m/z 354 (M+); Found: C, 64.36; H, 5.33; N, 7.69.
C19H18N2O5
: requires C, 64.40; H, 5.12; and N, 7.91%.
(E)-methyl 3-(2-methoxy-2-oxoethyl)-5-methyl-4-((5-bromo-indolin-2-one
-3-ylidene)methyl)-1H-pyrrole-2-carboxylate (1d) was
recrystallized from ethanol-water, yield 91%: mp 243 °C;
1H NMR (400 MHz, CDCl3):
d9.10 (br, 1H), 7.70 (s, 1H), 7.38 (t, 2H), 7.19
(s, 1H), 6.78 (t, 2H), 3.90 (s, 3H), 3.88 (s, 2H), 3.67 (s, 3H) and
2.20 (s, 3H); 13C NMR (75.5 MHz, DMSO):
d12,60, 30.97, 38.87, 39.29, 40.12, 51.61, 112.62, 117.83, 119.09, 123.97, 124.54, 126.33, 130.11, 131.50, 133.35, 141.45, 169.58 and 170.90; EI-MS
m/z 432(M+); Found: C, 52.51; H, 3.88; N, 6.17.
C19H17BrN2O5
: requires C, 52.67; H, 3.95; and N, 6.47%.
(E)-ethyl 3,5-dimethyl-4-((indolin-2-one-3-ylidene)methyl)-1
H-pyrrole-2- carboxylate (1e) was recrystallized from ethanol-water, yield
94%: mp 185 °C; 1H NMR (400 MHz, DMCO):
d 7.55 (s, 1H), 6.83_7.20 (m, 4H), 4.35 (q, 2H), 2.19 (s, 3H), 2.06 (s, 3H) and 1.36 (t, 3H);
13C NMR (75.5 MHz, DMSO):d13.12, 14.27, 60.00, 108.91, 115.72, 120.8, 122.00, 124.32, 126.75, 127.53, 128.33, 131.62, 133.83,
134.15, 147.86, 157.68, 160.07 and 170.42; EI-MS
m/z 310 (M+); Found: C, 69.46; H, 5.65; N, 9.00.
C18H18N2O3
: requires C, 69.66; H, 5.85; and N, 9.03%.
(E)-ethyl 3,5-dimethyl-4-((5-bromo-indolin-2-one-3-ylidene)methyl)-1
H -pyrrole-2- carboxylate (1f) was recrystallized from
ethanol-water, yield 95%: mp 213 °C;
1H NMR (400 MHz, CDCl3): d
9.08 (br, 1H), 7.81 (s, 1H), 7.72 (s, 1H), 7.31 (d, 2H), 7.17 (s, 1H), 6.75 (d, 2H),
4.35 (q, 2H), 2.19 (s, 3H), 2.06 (s, 3H) and 1.36 (t, 3H);
EI-MS m/z 388 (M+); Found: C, 55.44; H, 4.12; N, 7.18.
C18H17BrN2O3
: requires C, 55.54; H, 4.40; and N, 7.20%.
(E)-ethyl
3,5-dimethyl-4-((5-nitro-indolin-2-one-3-ylidene)
methyl)-1H- pyrrole-2-carboxylate (1g) was recrystallized from
ethanol-water, yield 95%: mp 286 °C;
1H NMR (400 MHz, DMSO): d 8.18 (d, 2H), 7.70 (s, 1H), 7.65 (s, 1H), 7.05 (d, 2H), 4.22 (q, 2H), 3.98 (q, 2H),
3.77 (s, 2H), 2.09 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 3H);
EI-MS m/z 355 (M+); Found: C, 60.78; H, 4.75; N, 11.73.
C18H17N3O5
: requires C, 60.84; H, 4.82; and N, 11.83%.
(E)-methyl 3,5-dimethyl-4-((indolin-2-one-3-ylidene)methyl)-1
H-pyrrole-2- carboxylate (1h) was recrystallized from ethanol-water,
yield 94%: mp 213 °C; 1H NMR (400 MHz, DMCO):
d 7.55 (s, 1H), 6.83_7.20 (m, 4H), 3.75 (s, 3H), 2.20 (s, 3H) and 2.06 (s, 3H); EI-MS
m/z 296 (M+); Found: C, 68.89; H, 5.78; N, 9.10.
C17H16N2O3
:requires C, 68.91; H, 5.44; and N, 9.45%.
(E)-methyl 3,5-dimethyl-4-((5-nitro-indolin-2-one-3-ylidene)methyl)-1
H- pyrrole-2-carboxylate (1i) was recrystallized from
ethanol-water, yield 95%: mp 218 °C;
1H NMR (400 MHz, DMSO): d 8.15 (d, 2H), 7.71 (s, 1H), 7.66 (s,
1H), 7.00 (d, 2H), 3.75 (s, 3H), 2.20 (s, 3H) and 2.06 (s, 3H); EI-MS
m/z 341 (M+); Found: C, 59.61; H,
4.58; N, 12.47.
C17H15N3O5
: requires C, 59.82; H, 4.43; and N,
12.31%.
(E)-ethyl
3,5-dimethyl-4-((5-nitro-indolin-2-one-3-ylidene)methyl)-1
H- pyrrole-2-carboxylate (1j) was recrystallized from
ethanol-water, yield 91%: mp 341 °C;
1H NMR (400 MHz, DMSO): d
8.18 (d, 2H), 7.70 (s, 1H), 7.65 (s, 1H), 7.05 (d,
2H), 4.22 (q, 2H),
3.98 (q, 2H), 3.77 (s), 2.09 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 3H);
EI-MS m/z 427 (M+); Found: C, 54.55; H, 4.56; N, 6.10.
C21H21N3O7
: requires C, 54.68; H, 4.59; and N, 6.07%.
(E)-3-((4-(2-ethoxy-2-oxoethyl)-5-(ethoxycarbonyl)-2-methyl-1
H-pyrrol-3-yl)methylene)-indolin-2-one-5-carboxylicacid (1k) was recrystallized from ethanol-water, yield 95%: mp 214 °C;
1H NMR (400 MHz, DMSO): d 7.82 (d, 2H), 7.56 (s, 1H), 7.54 (s, 1H), 6.98 (q, 2H),
4.21 (q, 2H), 3.98 (q, 2H), 3.77 (s, 2H), 2.09 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 3H). EI-MS
m/z 426 (M+); Found: C, 61.25; H, 5.57; N, 6.23.
C22H22N2O7
: requires C, 61.97; H, 5.20; and N, 6.57%.
(E)-ethyl 4-((5-aminosulfonyl-indolin-2-one-3-ylidene)methyl)-3-(2-ethoxy
-2-oxoethyl)-5-methyl-1H-pyrrole-2-carboxylate (1l) was
recrystallized from ethanol, yield 70%: mp 148_150 °C;
1H NMR (400 MHz, CDCl3): d 7.60 (s, 1H), 7.59 (d, 1H), 7.22 (s, 1H), 7.06 (d, 1H),
4.25 (q, 2H), 3.98 (q, 2H), 3.80 (s, 2H), 2.10 (s, 3H), 1.28 (t, 3H) and 1.05 (t, 3H). EI-MS
m/z 461 (M+); HRMS (EI)
m/z calcd
C21H23N3O7
S (M+) 461.1257, found 461.1251.
(E)-ethyl 4-((5-methylaminosulfonyl-indolin-2-one-3-ylidene)methyl)-3-
(2-ethoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2-carboxylate
(1m) was recrystallized from ethanol, yield 67%: mp126 °C;
1H NMR (400 MHz, CDCl3): d 9.31 (s,
1H), 8.41 (s, 1H), 7.8 (s, 1H), 7.63 (d, 1H), 7.42 (s, 1H), 7.00 (d, 1H), 4.32 (q, 2H), 4.10 (q, 2H), 3.80 (s, 2H), 2.42 (s, 3H), 2.10 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 2H); EI-MS
m/z 475 (M+). HRMS (EI)
m/z calcd
C22H25N3O7
S (M+)
475.1413, found 475.1408.
(E)-ethyl 4-((5-morpholinylaminosulfonyl-indolin-2-one-3-ylidene)methyl)-
3-(2-ethoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2-carboxy
late (1n) was recrystallized from ethanol, yield 62%:
mp 185 °C; 1H NMR (400 MHz,
CDCl3): d 9.31 (s, 1H), 8.41 (s, 1H), 7.80 (s, 1H),
7.63 (d, 1H), 7.42 (s, 1H), 7.00 (d, 1H), 4.32 (q, 2H),
4.10 (q, 2H), 3.80 (s, 2H), 3.67 (t, 2H), 2.90 (t, 2H), 2.10 (s, 3H),
1.36 (t, 3H) and 1.20 (t, 2H); EI-MS m/z 531
(M+); HRMS (EI) m/z calcd
C25H29N3O8
S (M+) 531.1675, found 531.1605.
(E)-ethyl 4-((5-(3-chlorophenyl)aminosulfonyl-indolin-2-one-3-
ylidene)methyl)-3-(2-ethoxy-2-oxoethyl)-5-methyl-1
H-pyrrole-2-carboxylate (1o) was recrystallized from ethanol, yield 72%: mp 118_120 °C;
1H NMR (400 MHz, DMSO): d 7.56 (m, 2H), 7.38 (s,1H),
6.80-6.98 (m, 5H), 4.21 (q, 2H), 3.98 (q, 2H), 3.77 (s, 2H),
2.00 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 3H).EI-MS
m/z 571 (M+); HRMS (EI)
m/z calcd
C27H26ClN3O7
S (M+): 571.1180, found 571.1178.
(E)-ethyl 4-((5-(3-fluorophenyl)aminosulfonyl-indolin-2-one-3-ylidene)
methyl)-3-(2-ethoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2-
carboxylate (1p) was recrystallized from ethanol, yield 73%: decomposes over 120 °C;
1H NMR (400 MHz, DMSO): d 7.55 (m, 2H), 7.39 (s,
1H), 6.80_6.98 (m, 5H), 4.21 (q, 2H), 3.98 (q, 2H), 3.77 (s, 2H), 2.00 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 3H); EI-MS
m/z 555 (M+); HRMS (EI)
m/z calcd
C27H26FN3O7
S (M+): 555.1476, found 555.1426.
(E)-ethyl 4-((5-dimethylaminoaminosulfonyl-indolin-2-one-3-ylidene)
methyl)-3-(2-ethoxy-2_oxoethyl)-5-methyl-1H-pyrrole-2-car
boxylate (1q) was recrystallized from ethanol, yield 65%: mp
145 °C; 1H NMR (400 MHz,
CDCl3): d 9.32 (br, 1H), 8.43 (s, 1H),
7.80 (s, 1H), 7.63 (d, 1H), 7.42 (s, 1H), 7.00 (d, 1H), 4.32 (q, 2H),
4.10 (q, 2H), 3.80 (s, 2H), 2.43 (s, 6H), 2.10 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 2H). EI-MS
m/z 489 (M+); HRMS (EI)
m/z calcd
C23H27N3O7
S (M+): 489.1569, found 489.1556.
(E)-ethyl 4-((5-(3-fluoro-4-chlorophenyl)aminosulfonyl-indolin-2-one-3 -ylidene)
methyl)-3-(2-ethoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2-carboxylate (1r) was recrystallized from ethanol, yield 70%: decomposes over 130 °C;
1H NMR (400 MHz, DMSO): d 7.56 (m, 2H),
7.38 (s, 1H), 6.87-6.98 (m, 4H), 4.21 (q, 2H), 3.98 (q, 2H), 3.77 (s, 2H), 2.00 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 3H); EI-MS
m/z 589 (M+); HRMS (EI)
m/z calcd
C27H25ClFN3O7
S (M+): 589.1086, found 589.1056.
(E)-ethyl4-((5-hexahydropiperidinylaminosulfonyl-indolin-2-one-3-ylidene)
methyl)-3-(2-ethoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2-
carboxylate (1s) was recrystallized from ethanol, yield 60%: mp145 °C;
1H NMR (400 MHz, DMSO): d 11.20 (s, 1H), 9.99 (s, 1H), 7.70 (s,
1H), 7.62 (d, 2H), 6.42 (s, 1H), 7.17 (q, 2H), 4.28 (q, 2H), 4.00 (q, 2H), 3.95 (s, 2H), 2.11 (s, 3H), 1.60 (m, 6H), 1.42 (m, 4H), 1.30 (t, 3H)
and 1.15 (t, 3H); EI-MS m/z 530
(M++1); HRMS (EI) m/z calcd
C26H31N3O7
S (M+): 529.1883, found 529.1856.
(E)-ethyl 4-((5-(3-bromophenyl)aminosulfonyl-indolin-2-one-3-ylidene) methyl)-3-(2-ethoxy-2-oxoethyl)-5-methyl-1H-pyrrole-2-
carboxylate (1t) was recrystallized from ethanol, yield 73%: mp 134_138 °C;
1H NMR (400 MHz, DMSO): d7.56 (m, 2H), 7.38 (s, 1H),
6.80_6.98 (m, 5H), 4.21 (q, 2H), 3.98 (q, 2H), 3.77 (s, 2H), 2.00 (s, 3H), 1.36 (t, 3H) and 1.20 (t, 3H); EI-MS
m/z 615 (M+); HRMS (EI)
m/z calcd
C27H26BrN3O7
S (M+): 615.0675, found 615.0672.
References
1 Ullrich A, Schlessinger J. Signal transduction by receptors with tyrosine kinase activity. Cell 1990; 61: 203_12.
2 Aaronson SA. Growth factors and cancer. Science 1991; 254: 1146_53.
3 Boschelli DH, Wu Z, Klutchko SR, Showalter HDH, Hamby JM, Lu GH,
et al. Synthesis and tyrosine kinase inhibitory activity of a series
of 2-amino-8H-pyrido[2,3-d]pyrimidines: identification of potent, selective platelet-derived growth factor receptor tyrosine kinase
inhibitors. J Med Chem 1998; 41: 4365_77.
4 Alexander JB. Chemical inhibitors of protein kinases. Chem Rev 2001; 101: 2541_72.
5 Traxler P, Furet P. Strategies toward the design of novel and selective protein tyrosine kinase inhibitors. Pharmacol Ther 1999; 82:
195_206.
6 Cance WG, Liu ET. Protein kinase in human breast cancer. Breast Cancer Res Treat 1995; 35: 105_14.
7 Chrysogelos SA, Dickson RB. Egf receptor expression, regulation, and function in breast cancer. Breast Cancer Res Treat 1994; 29:
29_40.
8 Yang EB, Wang DF, Cheng Y, Mack P. Expression and functions of growth-factors and growth-factor receptors in liver-cancer. Cancer
J 1997; 10: 319_24.
9 Yang EB, Guo YJ, Zhang K, Chen YZ, Mack P. Inhibition of epidermal growth factor receptor tyrosine kinase by chalcome derivatives.
Biochim Biophys Acta 2001; 1550: 144_50.
10 Traxler P, Bold G, Buchdunger E, Caravatti G, Furet P, Manley P,
et al. Tyrosine kinase inhibitors: from rational design to clinical trials.
J Med Res Rev 2001; 21: 499_512.
11 Kurup A, Garg R, Hansch C. Comparative QSAR study of
tyrosine kinase inhibitors. Chem Rev 2001; 101: 2573_600.
12 Khazaie K, Schirrmacher V, Lichtner RB. EGF receptor in neoplasia and metastasis. Cancer Metast Rev 1993; 12: 255_74.
13 Fry DW, Kraker AJ, McMichael A, Ambroso LA, Nelson JM, Leopold WR,
et al. A specific inhibitor of the epidermal growth factor
receptor tyrosine kinase. Science 1994; 265: 1093_5.
14 Smaill JB, Rewcastle GW, Loo JA, Greis KD, Chan OH, Reyner, EL,
et al. Tyrosine kinase inhibitors. 17. Irreversible inhibitors of the
epidermal growth factor receptor: 4-(phenylamino)quinazoline- and
4-(phenylamino)pyrido[3,2-d]pyrimidine-6-acrylamides bearing
additional solubilizing functions. J Med Chem 2000; 43: 1380_97.
15 Traxeler P, Bold G, Frei J, Lang M, Lydon N, Mett H,
et al. Use of a pharmacophore model for the design of EGF-R tyrosine kinase
inhibitors: 4-(phenylamino)pyrazolo[3,4-d]pyrimidines. J Med Chem 1997; 40: 3601_16.
16 Wissner A, Overbeek E, Reich MF, Floyd MB, Johnson BD, Mamuya N,
et al. Synthesis and structure-activity relationships of
6,7-disubstituted 4-anilinoquinoline-3- carbonitriles. The design of an orally active, irreversible inhibitor of the tyrosine kinase activity of the
epidermal growth factor receptor (EGFR) and the human epidermal growth factor receptor-2 (HER-2). J Med Chem 2003; 46: 49_63.
17 Palmer BD, Trumpp-Kallmeyer S, Fry DW, Nelson JM, Showalter HDH, Denny WA. Tyrosine kinase inhibitors. 11. Soluble analogues
of pyrrolo- and pyrazoloquinazolines as epidermal growth factor receptor inhibitors: synthesis, biological evaluation, and modeling of the
mode of binding. J Med Chem 1997; 40: 1519_29.
18 Sun L, Tran N, Liang C, Tang F, Rice A, Schreck
R, et al. Design, synthesis, and evaluations of substituted
3-[(3-or4-carboxyethyl-pyrrol-2-yl)methylidenyl]indolin-2-ones as inhibitors of VEGF, FGF, and PDGF receptor tyrosine kinases. J Med Chem 1999; 42: 5120_30.
19 Sun L, Tran N, Tang F, App H, McMahon G, Tang C. Synthesis and biological evaluations of 3-substituted indolin-2-ones: a novel class
of tyrosine kinase inhibitors that exhibit selectivity toward particular receptor tyrosine kinases. J Med Chem 1998; 41: 2588_603.
20 Mohammadi M, McMahon G. Structures of the tyrosine kinase domain of fibroblast growth factor receptor in complex with inhibitors.
Science 1997; 276: 955_60.
21 Battersby AR, Hunt E, McDonald E, Paine III JB, Saunders J. Biosynthesis of porphrins and related macrocycles. Part VIII. Enzymic
decarboxylation of uroporphyrinogen-III: structure of an intermediate, phyriaporphyrinogen-III, and synthesis of the corresponding
porphyrin and of two isomeric porphrins. J Chem Soc Perk I 1976; 1008_21.
22 Guo XN, Zhong L, Zhang XH, Zhao WM, Zhang XW, Lin LP,
et al. Evaluation of active recombinant catalytic domain of human
ErbB-2 tyrosine kinase, and suppression of activity by a naturally derived inhibitor, ZH-4B. Biochim Biophys Acta 2004; 1673: 186_93.
23 Wang S, Yang D, Enyedy I. Erbb-2 selective small molecule kinase inhibitors. US patent 2004023957-A1. 2004.
24 Mosmann T. An in
vitro murine model of a penicillin specific IgE anamnestic response. J Immunol Methods 1983; 139: 55_60.
25 Origin. Version 7.0. Northampton, MA: Microcal Software Inc, 2002. [cited 2005 Jul 20]. Available from: www.microcal.com.
26 Berman HM, Westbrook J, Feng Z, Gilliland G, Bhat TN, Weissig H,
et al. The protein data bank. Nucleic Acids Res 2000; 28: 235_42.
27 Sybyl molecular modeling package (Computer program). Version 6.8. St Louis, MO: Tripos Associates, 2000.
28 Weiner SJ, Kollman PA, Case DA, Singh UC, Ghio C, Alagona G,
et al. A new force field for molecular mechanical simulation of
nucleic acids and proteins. J Am Chem Soc 1984; 106: 765_84.
29 Gasteiger J, Marsili M. Iterative partial equalization of orbital electronegativity — a rapid access to atomic charges. Tetrahedron 1980;
36: 3219_88.
30 Morris GM, Goodsell DS, Halliday RS, Huey R, Hart WE, Belew RK,
et al. Automated docking using a Lamarckian genetic algorithm and
an empirical binding free energy function. J Comput Chem 1998; 19: 1639_62.
31 Morris GM, Goodsell DS, Halliday RS, Huey R, Hart WE, Belew RK,
et al. Autodock (Version 3.0.3), Molecular Graphics Laboratory,
Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA, USA. 1999.
32 Case DA, Pearlman DA, Caldwell JW, Cheatham TE III, Ross WS, Simmerling CL,
et al. AMBER 5.1, 5th ed, San Francisco, CA:
University of California; 1997.
33 Liu H, Li Y, Song M, Tan X, Cheng F, Zheng S,
et al. Structure-based discovery of potassium channel blockers from natural products:
virtual screening and electrophysiological assay testing. Chem Biol 2003; 10: 1103_13.
34 POV-ray. Version 3. POV-ray-Team, 1999. [cited 2005 Jul 20]. Available from: www.povray.org.
35 Usack KP, Arnold LD, Barberis CE, Chen HP, Ericsson AM, Gaza-Bulseco GS,
et al. A 13C NMR approach to categorizing potential
limitations of a, b-unsaturated carbonyl systems in drug-like molecules. Bioorg Med Chem Lett 2004; 14: 5503_7
36 John B, Dolphin D. Pyrrole chemistry. An improved synthesis of ethyl pyrrole-2-carboxylate esters from diethyl aminomalonate. J Org
Chem 1985; 50: 5598_604.
37 Sheldrick GM. SHELXS-97: Program for the solution of crystal structure. Germany: Goettingen Univ; 1997.
38 Beurskens PT, Admiraal B, Beurskens G, Bosman WP, Garcia-Granda S, Gould RO,
et al. The DIRIDIF-94 program system. Technical
report of the crystallography laboratory. The Nether-lands: University of Nijmegen, 1994.
39 Cromer DT, Waber JT. International tables for X-ray crystallo-graphy. Vol 4. Kynoch Press and Birmingham: England, 1974.
40 Ibers JA, Hamilton WC. Dispersion corrections and crystal structure refinements. Acta Cryst 1964; 17: 781_2.
41 Creagh DC, Hubbell JH. International tables for crystallography.
In: Wilson AJC editor. Boston: Kluwer Academic Publishers: 1992.
|
