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

2588

J . Med. Chem. 1998, 41, 2588-2603

Syn th esis a n d Biologica l Eva lu a tion s of 3-Su bstitu ted In d olin -2-on es: A Novel

Cla ss of Tyr osin e Kin a se In h ibitor s Th a t Exh ibit Selectivity tow a r d P a r ticu la r

Recep tor Tyr osin e Kin a ses

Li Sun,* Ngoc Tran, Flora Tang, Harald App, Peter Hirth, Gerald McMahon, and Cho Tang*

SUGEN, Inc., 351 Galveston Drive, Redwood City, California 94063

Received February 24, 1998

3-Substituted indolin-2-ones have been designed and synthesized as a novel class of tyrosine

kinase inhibitors which exhibit selectivity toward different receptor tyrosine kinases (RTKs).

These compounds have been evaluated for their relative inhibitory properties against a panel

of RTKs in intact cells. By modifying the 3-substituted indolin-2-ones, we have identified

compounds which showed selective inhibition of the ligand-dependent autophosphorylation of

various RTKs at submicromolar levels in cells. Structure-activity analysis for these compounds

and their relative potency and selectivity to inhibit particular RTKs has determined that (1)

3-[(five-membered heteroaryl ring)methylidenyl]indolin-2-ones are highly specific against the

VEGF (Flk-1) RTK activity, (2) 3-(substituted benzylidenyl)indolin-2-ones containing bulky

group(s) in the phenyl ring at the C-3 position of indolin-2-ones showed high selectivity toward

the EGF and Her-2 RTKs, and (3) the compound containing an extended side chain at the C-3

position of the indolin-2-one (16) exhibited high potency and selectivity when tested against

the PDGF and VEGF (Flk-1) RTKs. Recent published crystallographic data for two of these

3-substituted indolin-2-ones provides a rationale to suggest that these compounds may bind

in the ATP binding pocket of RTKs. The structure-activity analysis supports the use of subsets

of these compounds as specific chemical leads for the development of RTK-specific drugs with

broad application for the treatment of human diseases.

In tr od u ction

potency and specificity toward the EGF RTK. These

chemical classes have provided the basis for the selec-

tion of drug candidates for the treatment of EGF-de-

pendent human cancers. Biochemical and kinetic stud-

ies using the 4-(phenylamino)quinazolines have sug-

gested that these compounds inhibit the EGF RTK in

an ATP-competitive manner.¹³Models based upon the

cAMP-dependent kinase have been used to help define

how these molecules may localize in the ATP binding

pocket of the EGF RTK.^11,13The planar quinazoline

core structure has been proposed to bind to the ATP

binding cleft and the substituents around the core struc-

ture have been suggested to confer specificity through

unique interactions between these inhibitors and a few

kinase-specific amino acid residues present in the ATP

binding sites of the EGF RTK.¹³

Receptor tyrosine kinases (RTKs) have been shown

to be important mediators of cellular signal transduction

in cells.^1,2Many RTKs have been shown to be oncogene

products implicating their role in the transformation

process associated with human cancers.³In this regard,

deregulated RTK activity has been shown to play a role

in abnormal cell functions associated with the growth,

survival, and spread of human tumors.⁴In a broader

sense, increased RTK activity has been implicated in

atherosclerosis, vascular restenosis, fibrosis of the lung,

liver, and kidney, inflammatory disease, and other

immune-mediated disorders.^2,3As a consequence of

these associations, RTKs have been viewed as attractive

therapeutic targets for the development of novel agents

with novel mechanisms to treat human disease.⁵Over

the past decade, many investigators have sought to

identify small molecules that block RTK function.

However, only recently has it been possible to identify

several chemical classes that would inhibit kinase

activity associated with particular RTK types.^6-8In this

regard, in vitro testing of compounds for inhibitory

properties against a wide variety of kinases has pro-

vided the rationale to pursue particular chemical sub-

types as RTK-specific drug leads.

Recently, we have elucidated the crystallographic

structure of 3-substituted indolin-2-ones in the catalytic

core of the fibroblast growth factor (FGF) RTK.¹⁴In this

study, the indolin-2-one core was shown to occupy a site

in which the adenine of adenosine triphosphate binds

and the substituents around the indolin-2-one core were

shown to extend into the hinge region between the two

kinase lobes. In this case, compound 42 (3-[(3-(2-car-

boxyethyl)-4-methylpyrrol-2-yl)methylidenyl]indolin-2-

one) (Table 2) was shown to inhibit the FGF RTK in a

specific manner and induced conformational changes in

the nucleotide-binding loop that may, in part, explain

the potency and specificity of this compound. In the

present study, we provide data to suggest that various

substituents around the indolin-2-one core can contrib-

ute to the potency and specificity of this chemical class

Recent studies to identify inhibitors of the epidermal

growth factor (EGF) RTK have been quite successful.

(Phenylamino)quinazolines,⁹pyridopyrimidines,¹⁰pyr-

rolopyrimidines,¹¹and pyrazolopyrimidines¹²have been

identified and exhibit promising in vitro and in vivo

* To whom correspondence should be addressed.

Published on Web 06/09/1998

Synthesis, Evaluation of 3-Substituted Indolinones

J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2589

Sch em e 1. Preparations of 3-Substituted Indolin-2-ones

Ch a r t 1. Structures and Biological Evaluations of the

Three Lead 3-Substituted Indolin-2-ones (1-3)

of compounds containing different five-membered het-

eroaryl rings, including thiophene (Table 3), furan

(Table 4), and pyrazole (Table 5), at the C-3 position of

indolin-2-one. The impact of the substituents on the

indolin-2-one ring on the potency and selectivity of the

inhibitors was also examined.

on various RTKs. This study provides the basis to

associate subsets of 3-substituted indolin-2-ones as

specific chemical leads for the development of particular

RTK-specific drugs with broad application to the treat-

ment of human diseases.

Ch em istr y

3-Substituted indolin-2-ones were prepared by con-

densing substituted indolin-2-ones and aldehydes or

ketones in the presence of bases (Scheme 1). Indolin-

2-one (oxindole), 5-chlorooxindole, and most of the

aldehydes were commercially available, whereas 5-ni-

tro-, 4-methyl-, 5-bromo-, 5-methyl-, and 6-fluorooxin-

doles and a few aldehydes have been prepared by means

of reported or newly developed methods. 5-Nitrooxin-

dole was prepared by nitration of the oxindole at -5 to

0 °C followed by recrystallization in aqueous acetic

acid.¹⁵4-Methyloxindole has been prepared by reported

procedures.¹⁶6-Fluorooxindole (6) was prepared start-

ing from 2,5-difluoronitrobenzene according to literature

procedures¹⁷with some modifications (Scheme 2). Dis-

placement of o-fluoro substitution of 2,5-difluoroni-

trobenzene with dimethyl malonate followed by hydro-

lytic decarboxylation with 6 N aqueous hydrochloric acid

gave 4-fluoro-2-nitrophenylacetic acid (5). Reductive

cyclization of 5 under hydrogenation conditions resulted

in the generation of 6. 5-Bromooxindole (7) was pre-

pared by bromination of oxindole with NBS in acetoni-

trile at 0 °C (Scheme 2). Synthesis of 5-methyloxindole

(8) was achieved by a Wolff-Kishner-like reduction of

5-methylisatin with hydrazine hydrate (Scheme 2).¹⁸

Most of the aldehydes (9-12) which are not com-

mercially available were prepared by a Vilsmeier formy-

lation reaction starting from commercially available

chemicals (Scheme 3).

Discover y a n d Design of 3-Su bstitu ted

In d olin -2-on es a s RTK In h ibitor s

Using a random-screening approach, we have identi-

fied three related compounds of the 3-substituted indo-

lin-2-ones (1-3 in Chart 1) that exhibited inhibitory

properties against various RTKs using whole-cell ligand-

dependent autophosphorylation assays. As shown in

Chart 1, both 1 and 3 were found to be potent and

selective inhibitors of the vascular endothelial growth

factor (VEGF) [fetal liver kinase-1 (Flk-1)] RTKs, whereas

2 was found to be nonselective for RTK inhibition. A

comparison of the chemical structures of these com-

pounds provided the foundation to suggest that various

structural features may impart changes in RTK speci-

ficity. Compound 1 contains a nitrogen atom attached

to the C-4′ position of the phenyl at the C-3 position of

the indolin-2-one, whereas 2 contains an isosteric me-

thine moiety. In addition, NMR analysis of these

compounds indicated differences in E and Z isomer

populations. Both 1 and 3 exist as Z isomers, but 2

adopts the E isomeric form. This preliminary analysis

suggested that the relative potency and selectivity of

these compounds for inhibition of these kinases may be

sensitive to the substituent at the C-4′ position of 1 or

the predominant Z-E configurations.

To extend these observations, we sought to expand

the chemical diversity of this structural type and

determine the structure-activity relationship (SAR) for

3-substituted indolin-2-one analogues using a panel of

cell-based RTK assays. Five classes of 3-substituted

indolin-2-ones were designed and synthesized: (A)

compound 1 analogues with different substituent(s) on

the phenyl ring at the C-3 position of the indolin-2-one

core (Table 1); (B) compound 3 analogues having dif-

ferent substituent(s) in the pyrrole ring at the C-3

position of indolin-2-one (Table 2); (C-E) three classes

The 3-substituted indolin-2-ones may exist as either

the Z or E isomer depending on the characteristics of

the substituents at the C-3 position of the 3-substituted

indolin-2-one (Tables 1-5). The two isomer forms could

be distinguished by either 1D or 2D NOE analysis

(Chart 2). The Z-configured compounds should show a

NOE effect between the proton at the C-4 position and

the vinyl proton, whereas the E-configured compounds

should have a NOE effect between the proton at the C-4

2590 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14

Sun et al.

Ch a r t 2. Determination of the Configurations for

Sch em e 2. Preparations of 6-Fluoro- (6), 5-Bromo- (7),

and 5-Methyloxindoles (8)

3-Substituted Indolin-2-ones Using NOE Experiments

shifts of its particular proton(s) is summarized in Tables

1-5. For example, NOE experiments demonstrated

that the chemical shifts for the protons at the C-2′ and

C-6′ positions in the phenyl ring at the C-3 position of

the 3-(substituted benzylidenyl)indolin-2-ones (Table 1)

were around 7.85-8.53 ppm for the Z isomer but 7.45-

7.84 ppm for the E isomer. We interpret this to be due

to 2′- or 6′-protons being deshielded by the carbonyl at

the C-2 position of the indolin-2-one ring in the Z isomer

form. In the E isomer form, these protons may be

shielded by the phenyl ring of the indolin-2-one core

structure. Thus, configurations of the compounds within

this series could be assigned based on the chemical

shifts of particular protons, H-2′ and/or H-6′, in the

molecules (Table 1).

Most of 3-(substituted benzylidenyl)indolin-2-ones

which do not have any substitution at the C-4 position

in general existed as the mixtures of both Z and E

isomer forms. Compound 3 analogues (Table 2) con-

taining a pyrrole substituent at the C-3 position of the

3-substituted indolin-2-ones existed exclusively as the

Z isomer forms (Table 2). Indolin-2-ones having 3-sub-

stituted thienyl group (Table 3) existed as Z isomers.

3-[(Substituted pyrazolyl)methylidenyl]indolin-2-ones

(Table 5) having a proton at the N-1′ position in the

pyrazole ring (62) existed as the Z isomer, but the

similar compound with substitution at the N-1′ position

of the pyrazole ring existed as the E isomer (63).

However, compounds with a 3-substituted furanyl moi-

ety existed as E isomers (Table 4).

Sch em e 3. Synthesis of the Corresponding Aldehydes

We have observed the equilibrium between the Z and

E isomer forms in polar solvents, such as methanol and

dimethyl sulfoxide (DMSO), or in the presence of light.

The E isomerism of the 3-(substituted benzylidenyl)-

indolin-2-ones in Table 1 may be the result of the steric

interaction between the carbonyl group at the C-2

position of the indolin-2-one ring and the proton at the

C-2′(6′) position of the phenyl ring in their Z isomeric

forms (Scheme 4). 3-[(Substituted furanyl)methylide-

nyl]indolin-2-ones appear to favor the E isomer form.

This may be due to the electrostatic repulsion between

the C-2 carbonyl oxygen atom of the indolin-2-one and

the O-1′ of furan in their Z isomer form (Scheme 4). On

the other hand, the predominance of the Z isomerism

of the 3-[(substituted pyrrolyl)methylidenyl]indolin-2-

ones and 3-[(substituted pyrazolyl)methylidenyl]indolin-

2-ones may be the result of the intramolecular hydrogen

bonding between the C-2 carbonyl oxygen atom of the

indolin-2-one ring and the proton on the N-1′ of pyrrole

or N-2′ of pyrazole rings (Scheme 4). Replacement of

the proton on the N-1′ position of the pyrrole (50) or

pyrazole (63) ring afforded E-configured compounds due

to the unfavorable interaction between the substitution

at the N-1′ position of the pyrrole or the lone pair at

the N-2′ position of the pyrazole ring and the carbonyl

oxygen atom at the C-2 position of the indolin-2-one ring

position and the proton(s) in the C-3 substitution of the

3-substituted indolin-2-ones. The configurations of

some of the compounds (reference compounds) were

determined using NOE analysis, while the configura-

tions of the remaining compounds were assigned by

comparison of their H NMR spectrum with those of the

reference compounds. The relationship between the

Z-E configuration of a compound and the chemical

1

Synthesis, Evaluation of 3-Substituted Indolinones

J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2591

Sch em e 4. Rationales for the Preferred Z or E

Configuration of 3-Substituted Indolin-2-ones

required to achieve 50% inhibition of tyrosine phospho-

rylation on various RTKs compared to ligand-stimulated

control reactions in the presence of vehicle alone (di-

methyl sulfoxide). Compounds with IC₅₀values greater

than 100 µΜ were considered inactive. The relative

selectivity of a given inhibitor was assessed using

calculated ratios of the IC₅₀values corresponding to

specific RTKs. The results are summarized in Tables

1-5.

The primary goal of this study was to establish an

initial SAR on these novel RTK inhibitors and to

identify compounds with high potency and selectivity

against particular RTKs as chemical leads. Five classes

of compounds were designed and synthesized in order

to provide answers to the following questions: (A) What

are the electronic and steric effects of the substitutions

in the phenyl ring of 1 or in the pyrrole ring of 3 at the

C-3 position of 3-substituted indolin-2-ones on the

inhibitory potency and specificity against various RTKs?

(B) Do different heteroaryl substitutions at the C-3

position of 3-substituted indolin-2-ones influence the

inhibitory activity of this series? (C) Is the Z isomer

the active form? (D) Is the vinyl proton essential for

the inhibitory activity? (E) What is the impact of the

substituent(s) in the indolin-2-one core structure on

potency and selectivity of the inhibitors against various

RTKs.

A. SAR of 3-(Su bstitu ted ben zylid en yl)in d olin -

2-on es. Compounds from Table 1 were synthesized and

represented analogues of the two initial leads, 1 and 2.

These compounds possess substituents on the phenyl

ring at the C-3 position of 3-substituted indolin-2-ones.

As mentioned above, there were two differences when

chemical structures of 1 and 2 were compared. The

former has a nitrogen atom and the latter an isosteric

methine attached to the C-4′ position of the phenyl

group at the C-3 position of 3-substituted indolin-2-one.

In addition, 1 exists as the Z isomer, but 2 exists

predominantly as the E isomer. Compound 1 was

shown to be a selective VEGF (Flk-1) RTK inhibitor,

whereas 2 is a nonselective RTK inhibitor. These

results suggested that electron-rich substitution (4′-

dimethylamino in 1) in the phenyl ring at the C-3

position of 3-substituted indolin-2-ones would have a

large impact on the configuration and subsequently the

inhibitory activity of inhibitors against various RTKs.

On the basis of these preliminary results, we designed,

synthesized, and evaluated a series of analogues of 1

with different electron-rich substituents at the C-4′

position of the phenyl ring at the C-3 position of

3-substituted indolin-2-ones. First we maintained the

nitrogen atom at the C-4′ position of 1 and incorporated

this nitrogen atom into the piperazine, morpholine,

pyrrolidine, or piperidine substitution. Second, we

replaced the 4′-dimethylamino substitution of 1 with

other electron-rich substituents such as a hydroxyl or

alkoxy moiety. Third, we introduced electron-with-

drawing substituents into the phenyl ring at the C-3

position of the indolin-2-ones. Fourth, based on our

knowledge of particular tyrphostins that have bulky

substituents and had been shown to be EGF RTK

inhibitors, bulky substituents, such as tert-butyl or

isopropyl, were added on the phenyl at the C-3 position

of the indolin-2-ones in order to achieve specific EGF

in the Z-configured form. The loss of the intramolecular

hydrogen bonding of such compounds is also responsible

for the E isomeric form. Electrostatic interaction be-

tween the C-2 carbonyl oxygen and partial positively

charged S-1′ of the 3-[(substituted thienyl)methylidenyl]-

indolin-2-ones favors the Z isomer form for the com-

pounds in Table 3.

Resu lts a n d Discu ssion

Structure-activity relationships (SAR) for inhibition

of ligand-dependent tyrosine phosphorylation by the

indolin-2-ones were determined in a panel of NIH3T3

mouse fibroblast lines engineered to overexpress various

RTKs including the human PDGF receptor â, the

murine VEGF receptor (Flk-1), the human EGF recep-

tor, and the human insulin-like growth factor-1 (IGF-

1) receptor.¹⁹To assess homology to the EGF receptor

family-2 (Her-2) (p185^erbB2) kinase activity, the cyto-

plasmic domain of the human Her-2 was engineered to

contain the extracellular and transmembrane domain

of the human EGF receptor. The chimeric receptor was

overexpressed in NIH3T3 cells, and ligand-dependent

Her-2 kinase activity was assessed following stimulation

of the receptor with EGF as described.¹⁹IC₅₀values

were defined as the concentration of a compound

2592 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14

Sun et al.

Ta ble 1. 3-(Substituted benzylidenyl)indolin-2-ones: Preferred Configurations Determined by NMR Experiments and Their

Inhibitory Activities toward Particular RTKs at the Cellular Level

Synthesis, Evaluation of 3-Substituted Indolinones

J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2593

Ta ble 1 (Continued)

RTK inhibitors. Last, to assess the importance of the

vinyl proton, we replaced the vinyl proton in compound

24 by a methyl group in compound 37. The SAR

analysis of these analogues of 1 is presented below.

We incorporated the 4′-nitrogen atom of 1 into dif-

ferent saturated heterocyclic rings to give 16 (4′-

piperazine), 19 (4′-morpholine), 23 (4′-pyrrolidine), and

24 (4′-piperidine). Evaluation of these compounds

indicated that they were inactive against the EGF, Her-

2, and IGF-1 RTKs as is the case of 1. Using the PDGF

RTK assay, 16 was 4-fold more potent and 19 2-fold less

potent than 1. In contrast, 23 and 24 were found to be

inactive against the PDGF RTK activity. However,

their inhibitory activity against the VEGF (Flk-1) RTK

was 2-6-fold less than that of 1. Interestingly, these

compounds showed similar potency against the VEGF

(Flk-1) RTK regardless of their predominant configura-

tions. However, our cocrystal study indicated that the

binding configuration for 16 was the Z form despite its

predominantly E isomer in solution (Table 1).¹⁴There-

fore, the E form of 16 has to be isomerized to the Z form

before or during the interaction with the VEGF (Flk-1)

RTK. Binding of the Z isomer to the catalytic site may

shift the Z-E equilibrium from the E isomer to the Z

form. This hypothesis may help to explain the loss of

potencies of 16, 19, 23, and 24 against the VEGF (Flk-

1) RTK activity relative to 1 which exists only in the

active Z form.

Since the Z configuration may be the preferred form

for the inhibitory activity of these inhibitors against

both the PDGF and VEGF (Flk-1) RTKs, we have

designed and synthesized conformationally constrained

3-substituted indolin-2-ones. In this regard, a methyl

group was introduced at the C-4 position of the 3-sub-

stituted indolin-2-ones in order to provide more steric

interactions with the substituent at the C-3 position.

In this case, the Z isomer form was more favored than

the E form (Scheme 4). Compound 17 and 20 (Table 1)

were prepared by introducing the methyl group at the

C-4 position of 16 and 19 (Table 1), respectively. Both

17 and 20 existed exclusively as Z isomers compared to

the predominant E isomer forms of their respective

parent compounds, 16 and 19. Compound 14, while

existing as a Z isomer like 1, was found to be inactive

against the PDGF RTK activity and about 4-fold less

active (IC₅₀) 3.0 µΜ) than 1 (IC₅₀) 0.8 µΜ) against

the VEGF (Flk-1) RTK activity. Therefore, substitution

at the C-4 position of the indolin-2-one core is unfavor-

able for the inhibitory activities against both the PDGF

and VEGF (Flk-1) RTKs. Compound 17 was found to

be 5-fold less potent than 16 against the PDGF RTK

activity. Compound 20 showed similar potency to 19

when tested against the PDGF and VEGF (Flk-1) RTK

activities despite the unfavorable interaction introduced

by the methyl substituent at the C-4 position. In

conclusion, the actual inhibitory activities of these

3-substituted indolin-2-ones may depend on the balance

between the positive inhibitory effect of the Z-configured

piperazine ring of 17 or the piperidine ring of 20 and

the negative inhibitory impact of the methyl group at

the C-4 position.

Other electron-rich substituents, such as a hydroxyl

or methoxy moiety (25 and 26, respectively) were also

introduced at the C-4′ position of the phenyl substitution

at the C-3 position of the 3-substituted indolin-2-ones.

Compound 25 containing the hydroxyl group at the C-4′

position selectively inhibited the VEGF (Flk-1) RTK

activity with an IC₅₀of 2.7 µΜ. Methylation of this

hydroxyl substitution at the C-4′ position in 25 gave 26

which specifically inhibits VEGF (Flk-1) RTK activity

with an IC₅₀value of 7.6 µΜ. In contrary, inhibitors

having electron-withdrawing substituents at the C-4′

position of the phenyl ring at the C-3 position of

3-substituted indolin-2-ones totally eliminated the in-

hibitory activity against any RTK, as evidenced by 27

and 28. This result suggests that an electron-rich

substituent may be essential for the inhibitory activity

against the VEGF (Flk-1) RTK, probably through an

impact on the equilibrium between Z and E forms.

Electron-rich substituents could establish a highly

2594 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14

Sun et al.

Ta ble 2. 3-[(Substituted pyrrol-2-yl)methylidenyl]indolin-2-ones: Preferred Configurations Determined by NMR Experiments and

Their Inhibitory Activity toward Particular RTKs at the Cellular Level

conjugated system, decrease the energy barrier between

the Z and E forms, and enable the Z-E equilibrium to

be established faster than the one without such electron-

rich substituents.

To examine the effects of the substituents around the

indolin-2-one ring on RTK inhibitory potency and

selectivity, 13, 15, 18, 21, and 22 have been synthesized.

Methyl substitution at the N-1 position of 13 abolishes

the inhibitory activity against the PDGF RTK activity

and results in 28-fold loss in potency against the VEGF

(Flk-1) RTK activity (IC₅₀) 22.6 µΜ) compared to 1.

This result indicated the importance of the proton at

the N-1 position for inhibitory activity of 1 and is in

agreement with our studies derived from the cocrystal

structure of 16 and FGF RTK catalytic domain.¹⁴In

this latter case, the proton at the N-1 position of 16 was

Synthesis, Evaluation of 3-Substituted Indolinones

J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2595

Ta ble 3. 3-[(Substituted thien-2-yl)methylidenyl]indolin-2-ones: Preferred Configurations Determined by NMR Experiments and

Their Inhibitory Activity toward Particular RTKs at the Cellular Level

Ta ble 4. 3-[(Substituted furan-2-yl)methylidenyl]indolin-2-ones: Preferred Configurations Determined by NMR Experiments and

Their Inhibitory Activity toward Particular RTKs at the Cellular Level

found to be involved in a critical hydrogen-bonding

interaction with the carbonyl oxygen of Glu562 within

the catalytic domain.¹⁴Compound 15, 6-fluoro-substi-

tuted 1, was found to be 3.4- and 5.8-fold less potent

than 1 against the PDGF and VEGF (Flk-1) RTK

activities, respectively. Thus, the electron-withdrawing

substituents on the indolin-2-one ring are unfavorable

for inhibitory activity against both the PDGF and VEGF

(Flk-1) RTKs.

To examine the effect of multiple substituents in the

phenyl ring on the RTK inhibitory potency and selectiv-

ity, a series of analogues of 25 and 26 were prepared

with substituents at the C-3′ and/or C-5′ position. In-

terestingly, the compound 25 analogue, 29 (which has

tert-butyl at the C-3′ and C-5′ positions), was found to

be active against not only the VEGF (Flk-1) RTK but

also the EGF and Her-2 RTK activities compared to 25.

In addition, the compound 26 analogue, 34 (which has

tert-butyl substitution at the C-3′ position), selectively

inhibited the Her-2 RTK activity. Compound 33, con-

taining 3′,5′-diisopropyl moieties (compound 25 ana-

logue), was found to be a nonselective RTK inhibitor.

Of particular interest, 36, the 5′-bromo analogue of the

parent 32, was a Her-2-specific inhibitor. Deleting the

5-chloro substitution of 32 resulted in 34 which was

shown to specifically inhibit the Her-2 RTK activity. In

contrary, deleting the 5-chloro substitution in compound

36 switched the selectivity from Her-2-specific to EGF/

Her-2/VEGF (Flk-1) RTK-selective (31). The same

5-chloro substitution in different compounds has an

2596 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14

Sun et al.

Ta ble 5. 3-[(Substituted pyrazol-3-yl)methylidenyl]indolin-2-ones: Preferred Configurations Determined by NMR Experiments and

Their Inhibitory Activity toward Particular RTKs at the Cellular Level

opposite impact on the inhibitory activity of these

inhibitors. This may be the result of different RTK

conformational changes induced by inhibitors containing

different structural features. A similar phenomenon

was observed for the 4-(phenylamino)quinazolines.⁹In

this series, specific inhibition of the EGF and Her-2 RTK

family was accomplished with compounds that contain

bulky lipophilic substitutions in the phenyl ring at the

C-3 position of the 3-substituted indolin-2-ones, whereas

selective inhibitors of the PDGF or/and VEGF (Flk-1)

RTK family contained electron-rich substitutions in the

phenyl ring.

This finding is in agreement with a cocrystal study of

the indolin-2-ones and the FGF RTK catalytic domain.¹⁴

The roles of the substituents in the indolin-2-one core

of these 3-[(substituted pyrrolyl)methylidenyl]indolin-

2-ones in the inhibitory activity against the PDGF and

VEGF (Flk-1) RTKs were evaluated. Compound 38, the

4-methyl analogue of 3, was found to be inactive when

tested against the PDGF RTK activity (IC₅₀> 100 µΜ)

and 79-fold less active (IC₅₀) 31.0 µΜ) than 3 when

tested against the VEGF (Flk-1) RTK activity. There-

fore, substitution at the C-4 position of the indolin-2-

one ring was found to have a negative impact on the

inhibitory activity of compounds when tested against

both PDGF and VEGF (Flk-1) RTK activities. This is

in accordance with conclusions following our SAR

analysis of 3-(substituted benzylidenyl)indolin-2-ones as

shown in Table 1. An electron-withdrawing chloro or

fluoro substitution in the indolin-2-one core of 39 or 40

decreased the potency and selectivity when tested

against the VEGF (Flk-1) RTK activity compared to 3.

The 5-nitro analogue (51) of 3 was found to be a weak

PDGF RTK inhibitor and was found to be inactive when

tested against the VEGF (Flk-1) RTK activity, suggest-

ing that the electron-withdrawing substituents at the

C-5 position of the indolin-2-ones may be detrimental

to inhibitory activities associated with this series of RTK

inhibitors.

To test the importance of the vinyl proton, compound

37, an analogue of 24 (Table 1), was synthesized and

evaluated. Both 37 and 24 exist as E isomers. How-

ever, compound 24, a specific VEGF (Flk-1) RTK inhibi-

tor, can be contrasted to 37 which was found to be

inactive when tested against any RTK activity in the

study. This demonstrates that the vinyl proton is

critical for the inhibitory activity of these novel RTK

inhibitors against VEGF (Flk-1) RTK.

B. 3-[(Su bstitu ted p yr r ol-2-yl)m eth ylid en yl]in -

d olin -2-on es (Com p ou n d 3 An a logu es). Since we

have found that 3 inhibits both VEGF (Flk-1) (IC₅₀

)

0.39 µΜ) and PDGF (IC₅₀) 12.0 µΜ) RTK activities,

we designed a series of inhibitors with different five-

membered rings at the C-3 position of 3-substituted

indolin-2-ones, including pyrrole (Table 2), thiophene

(Table 3), furan (Table 4), and pyrazole (Table 5). In

the pyrrole series (Table 2), most of the compounds were

found to exist as Z isomer forms and found to be inactive

against the EGF, Her-2, and IGF-1 RTK activities.

These compounds were found to be more potent and

selective than 3-(substituted benzylidenyl)indolin-2-ones

against the VEGF (Flk-1) RTK, and a few compounds

showed high inhibitory activity against the PDGF RTK

activity. Methylation at the N-1′ position of the pyrrole

in 3 resulted in a compound (50) that existed as an E

isomer and was shown to be a weak inhibitor of the

VEGF (Flk-1) RTK. This suggested that the Z isomer

is required for inhibiting the VEGF (Flk-1) RTK activity

by these 3-substituted indolin-2-ones.

To assess the impact of the substitutions on the

pyrrole ring of 3 on the inhibitory activity against the

VEGF (Flk-1) RTK, small alkyl or electron-withdrawing

groups were introduced into the pyrrole ring. Inhibitory

activities associated with compounds having small alkyl

and electron-withdrawing polar moieties at both the C-3′

and C-4′ positions in the pyrrole ring of 3 were found to

be either highly selective or specific toward the VEGF

(Flk-1) RTK as in the case of 42 and 44. On the other

hand, most of the compounds with substitutions at the

C-3′ and C-5′ positions in the pyrrole ring of 3 have

shown decreased potency when tested against the PDGF

RTK activity and maintained the good inhibitory activ-

ity when tested against the VEGF (Flk-1) RTK activity.

Compound 45, the 3′,5′-dimethyl analogue²⁰of 3, was

Synthesis, Evaluation of 3-Substituted Indolinones

J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2597

found to be slightly less potent than 3 when tested

against the PDGF (IC₅₀) 20.26 µΜ) and VEGF (Flk-1)

RTK (IC₅₀) 1.04 µΜ), respectively. Interestingly, the

4′-ethyl analogue (47) of 45 was found to be inactive

when tested against all of the RTK activities in the

panel, whereas the 4′-ethoxycarbonyl analogue (48) of

45 was found to be the most potent and selective VEGF

(Flk-1) RTK inhibitor shown in Table 2. In contrast,

compound 49 which has a 3′-ethyl-4′,5′-dimethylpyrrole

at the C-3 position of the indolin-2-ones was found to

be highly potent when tested against the VEGF (Flk-1)

RTK activity (IC₅₀) 0.14 µΜ) and weakly active when

tested against the PDGF RTK activity. These results

suggest that an electron-withdrawing polar substitution

at the C-4′ position of the pyrrole ring of 3 is favorable

for the VEGF (Flk-1) RTK inhibitory activity of these

inhibitors. Therefore, adjustment of substituents at the

C-4′ position could lead to highly potent and selective

inhibitors of the VEGF (Flk-1) RTK. Compound 52, the

4-methyl analogue of 45, was found to be inactive when

tested against the PDGF RTK activity and was found

to be 3-fold more potent than 45 when tested against

the VEGF (Flk-1) RTK activity. This result is in

contrary to the one derived from the 3-(substituted

benzylidenyl)indolin-2-ones. The methyl group at the

C-4 position of 14 (Table 1) has negative impact on the

potency toward both the PDGF and VEGF (Flk-1) RTKs.

In addition, the methyl substitution at the C-4 position

of 38 decreased the potency against both the PDGF and

VEGF (Flk-1) RTKs when compared to 3. Interestingly,

a methyl substitution at the C-5 position of 53 was found

to be 10-fold more potent than 45 when tested against

the VEGF (Flk-1) RTK activities. In summary, these

studies have shown that small electron-donating sub-

stituents at the C-4 or C-5 position were favorable for

inhibitory activity of the compounds containing 3′,5′-

dimethyl-substituted pyrrole at the C-3 position of the

indolin-2-ones when tested against the VEGF (Flk-1)

RTK.

was shown to specifically inhibit the VEGF (Flk-1) RTK

activity (IC₅₀) 7.41 µΜ). Alkylation at the N-1′ position

in the pyrazole ring of 62 resulted in 63 which was found

to be inactive against any RTK activity measured. NOE

NMR experiments indicated that 62 exists as the Z

isomer whereas 63 exists as the E isomer. We suggest

that the proton at the N-1′ position of the pyrazole ring

in 62 may migrate to the N-2′ position and allow

intramolecular hydrogen bonding with the carbonyl

oxygen atom at the C-2 position of the indolin-2-one

(Scheme 4). Such hydrogen bonding may be responsible

for the Z configuration of 62. Methylation at the N-1′

position of the pyrazole ring in 62 may disrupt the

hydrogen bonding and result in a repulsive interaction

between the lone pair electrons at the N-2′ position of

the pyrazole ring and the carbonyl oxygen at the C-2

position of the indolin-2-one. This model may help to

explain why 63 exists as the E isomer and why these

two compounds may have differences in inhibitory

activity against the VEGF (Flk-1) RTK.

Con clu sion s

This report describes the identification, characteriza-

tion, and SAR analysis of a novel chemical series of

tyrosine kinase inhibitors, 3-substituted indolin-2-ones,

which exhibit selectivity toward particular RTKs. In

this report, the potency and selectivity of an inhibitor

using cell-based assays can be further influenced by

many factors including vehicle solubility, membrane

permeability, chemical stability and metabolism, and

alternative targets that may affect RTK activation.

Nonetheless, SAR analysis can be very useful using

these assays to identify chemical leads when performed

with compounds that have similar physical and chemi-

cal properties. In this regard, we have shown that the

potency and selectivity of this chemical series depend

to a large extent on the configuration of the compound

as it relates to substitutions at the C-3 position of the

indolin-2-one core. The 3-[(substituted pyrrolyl-, thi-

enyl-, and pyrazolyl)methylidenyl]indolin-2-ones were

shown to exist exclusively or predominantly as Z

isomers and were also found to be highly selective

toward the VEGF (Flk-1) and/or PDGF RTK activity

while inactive or weakly active against the EGF, Her-

2, and IGF-1 RTK activities. The association of these

inhibitory activities with the Z isomeric forms was found

to be in agreement with our cocrystal studies using 16

and 42 bound in the catalytic core of the FGF RTK.¹⁴

In this latter study, the binding configurations for both

16 and 42 were found to be the Z isomer forms. Since

the primary amino acid sequences of the VEGF (Flk-1)

and PDGF receptor kinase domains are highly homolo-

gous to that of the FGF receptor kinase, we suggest that

the ability of many of the indolin-2-ones to show specific

inhibitory properties on the VEGF (Flk-1) and PDGF

RTKs may be due to the existence of Z isomers that can

bind into the ATP binding pocket of these RTKs. In

addition, the same study showed that the pyrrole ring

and the indolin-2-one ring in 42 are near coplanar due

to the intramolecular hydrogen bonding between the

proton at the N-1′ position and oxygen atom at the C-2

position of 42. The cocrystal X-ray structures of the

catalytic domain of the FGF receptor with 16 and 42

suggest that the 3-substituted indolin-2-one compounds

may bind at the ATP binding site with the indolin-2-

C. 3-[(Su bstitu ted th ien -2-yl)m eth ylid en yl]in -

d olin -2-on es. In the 3-[(substituted thien-2-yl)meth-

ylidenyl]indolin-2-one series (Table 3), we have deter-

mined that most of the compounds exist predominantly

as Z isomers. However, these compounds, in general,

are less potent than the 3-[(substituted pyrrol-2-yl)-

methylidenyl]indolin-2-ones against the VEGF (Flk-1)

RTK. Methyl substitution at the C-4 position of the

indolin-2-one ring eliminated the VEGF (Flk-1) RTK

inhibitory activity as in the case of 57 (IC₅₀> 100 µΜ)

when compared to the parent compound 56 (IC₅₀) 2.30

µΜ).

D. 3-[(Su bstitu ted fu r a n -2-yl)m eth ylid en yl]in -

d olin -2-on es. 3-[(Substituted furan-2-yl)methylidenyl]-

indolin-2-ones (Table 4) were found to exist as E

isomers. Given our model, it is not surprising that these

compounds were found to be weak inhibitors of the

VEGF (Flk-1) RTK and inactive against other RTK

activities measured. In addition, the furan ring is less

electron-rich than a pyrrole or thiophene ring. There-

fore, these electronic effects may also influence the

inhibitory activity of these compounds.

E. 3-[(Su bstitu ted p yr a zol-3-yl)m eth ylid en yl]-

in d olin -2-on es. In the series of 3-[(substituted pyrazol-

3-yl)methylidenyl]indolin-2-ones (Table 5), compound 62

2598 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14

Sun et al.

one ring occupying the adenine binding pocket. Biden-

tate hydrogen bonding between the indolin-2-one flat

core structure in the adenine binding site may play a

crucial role to block entry of ATP in the binding site.

Both the proton at the N-1 position and the oxygen atom

at the C-2 position of the indolin-2-one were found to

be coordinated to the peptide backbone within the

adenine binding cleft. In this regard, alkylation at the

N-1 position of the indolin-2-ones greatly decreases the

inhibitory potency of these 3-substituted indolin-2-ones

(13 vs 1) against both the PDGF and VEGF (Flk-1)

RTKs.

of human diseases including cancers, metastasis, arte-

rial restenosis, various inflammatory diseases including

psoriasis and rheumatoid arthritis, pulmonary fibrosis,

liver cirrhosis, kidney sclerosis, and other diseases. The

potential to design and synthesize 3-substituted indolin-

2-ones with inhibitory properties for various PTK

subtypes supports the use of compounds of this class to

treat a wide variety of human diseases.

Exp er im en ta l Section

NMR spectra were recorded by Acorn NMR using a Nicolet

NT300 or a Nicolet NT360 spectrometer. Tetramethylsilane

(TMS) was used as an internal standard and chemical shifts

are reported in parts per million (δ) downfield from TMS.

Coupling constants are reported in hertz. Mass spectra

(electron spray) were recorded by SYNPEP CORP, using an

API I PLUS spectrometer. Elemental analyses were per-

formed by Galbraith Laboratories, Inc. Elemental analyses

results are within (0.4% of the theoretical values.

In addition, we have suggested that the substitution

around the indolin-2-ones may be the key determinants

for the potency and especially specificity of the inhibi-

tors. A fluoro substitution at the C-6 position of the

3-[(substituted pyrrolyl)methylidenyl]indolin-2-ones

greatly increased the inhibitory activity against the

PDGF RTK (40 vs 3). A chloro substitution at the C-5

position of the 3-[(substituted pyrrolyl)methylidenyl]-

indolin-2-one decreased inhibitory activity against both

the PDGF and VEGF (Flk-1) RTKs (39 vs 3). A strong

electron-withdrawing nitro group was detrimental to the

inhibitory activity of 51 against the VEGF (Flk-1) RTK.

It was also observed that same substitution could have

different impacts on the inhibitory activity of different

inhibitors depending on other substitutions in the

molecules. In this regard, fluoro substitution at the C-6

position of 15 decreased the inhibitory activity against

both the PDGF and VEGF (Flk-1) RTK activities when

compared to 1. This may imply different conformational

changes of the enzyme induced by different inhibitors.

Therefore, different SAR conclusions have been drawn

for different types of 3-substituted indolin-2-ones. On

the other hand, some of the 3-(substituted benzylidenyl)-

indolin-2-ones that were found to be selective for both

the EGF and Her-2 receptors possessed bulky lipophilic

substitutions in the phenyl ring at the C-3 position of

3-(substituted benzylidenyl)indolin-2-ones. This result

may indicate structural differences in the ATP binding

sites when catalytic domains of the EGF and Her-2

RTKs are compared to those of the PDGF and VEGF

(Flk-1) RTKs.

Gen er a l P r oced u r e for 3-(Su bstitu ted ben zylid en yl)-

in d olin -2-on e An a logu es (Com p ou n d 1 An a logu es).

A

reaction mixture of the proper oxindole (1 equiv), aldehyde (1.2

equiv), and piperidine (0.1 equiv) in ethanol 1-2 mL/1 µmol

oxindole) was stirred at 90 °C for 3-5 h. After the mixture

cooled, the precipitate was filtered, washed with cold ethanol,

and dried to give the target compound in over 80% yield. The

analytical data reported here is for the major isomer. The data

for the minor isomer is not reported. The ratios of Z to E

isomers for each compound are shown in Table 1.

(Z)-3-[4-(Dim eth ylam in o)ben zyliden yl]in dolin -2-on e (1):

¹H NMR (300 MHz, DMSO-d₆) δ 10.46 (s, 1H, NH-1), 8.44 (d,

J ) 9.24 Hz, 2H, H-2′,6′), 7.60 (s, 1H, H-vinyl), 7.59 (d, J )

7.82 Hz, 1H, H-4), 7.11 (dt, J ) 1.02, 7.82 Hz, 1H, H-6), 6.93

(dt, J ) 0.89, 7.82 Hz, 1H, H-5), 6.80 (d, J ) 7.82 Hz, 1H,

H-7), 6.73 (d, J ) 9.24 Hz, 2H, H-3′,5′), 3.00 (s, 6H, N(CH₃)₃-

4′); MS m/z (relative intensity, %) 256 (100, [M + 1]^+•). Anal.

(C₁₇H₁₆N₂O‚0.1H₂O) C, H, N.

(Z)-1-Meth yl-3-[4-(dim eth ylam in o)ben zyliden yl]in dolin -

2-on e (13): ¹H NMR (360 MHz, DMSO-d₆) δ 8.47 (d, J ) 9.15

Hz, 2H, H-2′,6′), 7.67 (s, 1H, H-vinyl), 7.66 (d, J ) 7.79 Hz,

1H, H-4), 7.21 (dt, J ) 1.09, 7.79 Hz, 1H, H-6), 7.02 (dt, J )

0.99, 7.79 Hz, 1H, H-5), 6.95 (d, J ) 7.79 Hz, 1H, H-7), 6.78

(d, J ) 9.15 Hz, 2H, H-3′,5′), 3.22 (s, 3H, NCH₃-1), 3.05 (s,

6H, N(CH₃)₂-4′); MS m/z (relative intensity, %) 279 (100, [M

+ 1]^+•), 349 (100, [M + 1]^+•). Anal. (C₁₈H₁₈N₂O) C, H, N.

(Z)-4-Meth yl-3-[4-(dim eth ylam in o)ben zyliden yl]in dolin -

2-on e (14): ¹H NMR (360 MHz, DMSO-d₆) δ 10.40 (s, br, 1H,

NH-1), 8.32 (d, J ) 8.24 Hz, 2H, H-2′,6′), 7.61 (s, 1H, H-vinyl),

7.02 (t, J ) 7.81 Hz, 1H, H-6), 6.67-6.75 (m, 4H, H-5,7,3′,5′),

3.02 (s, 6H, N(CH₃)₂-4′); MS m/z (relative intensity, %) 278

(100, M^+•). Anal. (C₁₈H₁₈N₂O‚0.1H₂O) C, H, N.

(E)-6-Flu or o-3-[4-(dim eth ylam in o)ben zyliden yl]in dolin -

2-on e (15). 2-(4-F lu or o-2-n itr op h en yl)m a lon ic Acid Di-

m eth yl Ester (4). The reaction mixture of sodium hydride

(2.6 g, 108 µmol) and 14.5 g of dimethyl malonate (108 µmol)

in 160 mL of dimethyl sulfoxide was heated to 100 °C for 1 h.

The mixture was cooled to room temperature, and 7.95 g of

2,5-difluoronitrobenzene (70 µmol) was added and stirred for

30 min. The mixture was then heated to 100 °C for 1 h, cooled

to room temperature, and poured into 400 mL of saturated

ammonium chloride solution. The mixture was extracted with

200 mL of ethyl acetate and the organic layer washed with

brine, dried over anhydrous sodium sulfate, and concentrated

under vacuum. The residue was crystallized from methanol

to give 24.4 g (80% yield) of dimethyl 4-fluoro-2-nitrophenyl-

malonate as a white solid. The filtrate was concentrated and

chromatographed on a column of silica gel (ethyl acetate/

hexane, 1:8) to give 5.03 g of dimethyl 4-fluoro-2-nitrophenyl-

malonate (96% total yield): ¹H NMR (360 MHz, DMSO-d₆) δ

8.02 (dd, J ) 8.54, 2.48 Hz, 1H, H-3), 7.68 (dt, J ) 8.54, 2.48

Hz, 1H, H-5), 7.63 (dd, J ) 8.54, 5.63 Hz, 1H, H-6), 5.47 (s,

1H, CH(COOCH₃)₂-1), 3.70 (s, 6H, CH(COOCH₃)₂-1).

In summary of the SAR studies: (1) Proton at the N-1

position of the indolin-2-ones is essential for the inhibi-

tory activity against the PDGF and VEGF (Flk-1) RTKs.

(2) Vinyl proton is critical for 3-substituted indolin-2-

ones to inhibit the PDGF and VEGF (Flk-1) RTKs. (3)

Z Isomeric form is required for the inhibitory activity

against the PDGF and VEGF (Flk-1) RTKs. (4) 3-[(Sub-

stituted pyrrolyl)methylidenyl]indolin-2-ones are the

most potent and selective inhibitors of the PDGF and

VEGF (Flk-1) RTKs. (5) Electron-donating substitution

is preferred for the inhibitory potency of these 3-sub-

stituted indolin-2-ones against the PDGF and VEGF

(Flk-1) RTKs. (6) Bulky lipophilic groups in the phenyl

ring at the C-3 position of 3-(substituted benzylide-

nyl)indolin-2-ones are the key determinants for the

selective inhibitory activity of these inhibitors against

the EGF and Her-2 RTKs.

In conclusion, we described a chemical series that

shows promise in the development of RTK inhibitors

with the capacity to be specific to particular enzymes.

PTK function has been associated with a wide variety

Synthesis, Evaluation of 3-Substituted Indolinones

J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2599

Dimethyl 4-fluoro-2-nitrophenylmalonate (5.0 g, 18.5 µmol)

was refluxed in 20 mL of 6 N hydrochloric acid for 24 h. The

reaction mixture was cooled and the white solid collected by

vacuum filtration, washed with water, and dried to give 3.3 g

(87% yield) of 4-fluoro-2-nitrophenylacetic acid (5): ¹H NMR

(360 MHz, DMSO-d₆) δ 12.5 (s, br, 1H, CH₂COOH-1), 7.96 (d,

J ) 10.21 Hz, 1H, H-3), 7.58-7.61 (m, 2H, H-5,6), and 3.97

(s, 2H, CH₂COOH-1).

4-Fluoro-2-nitrophenylacetatic acid (3.3 g, 16.6 µmol) dis-

solved in 15 mL of acetic acid was hydrogenated over 0.45 g

of 10% palladium on carbon under 60 psi for 2 h. The catalyst

was removed by filtration and washed with 15 mL of methanol.

The combined filtrates were concentrated and diluted with

water. The precipitate was collected by vacuum filtration,

washed with water, and dried to give 1.6 g (70% yield) of

6-fluoroindolin-2-one (6): ¹H NMR (360 MHz, DMSO-d₆) δ

10.43 (s, br, 1H, NH-1), 7.17 (t, J ) 8.13 Hz, 1H, H-4), 6.69

(ddd, J ) 2.22, 8.13, 10.38 Hz, 1H, H-5), 6.60 (dd, J ) 2.22,

9.16, Hz, 1H, H-7), 3.42 (s, 2H, CH₂-3); MS m/z (relative

intensity, %) 153 (100, [M + 1]^+•).

P r ep a r a tion of 15. The title compound was prepared by

condensation of 6 and (dimethylamino)benzaldehyde using the

same method described for analogues of 1: ¹H NMR (360 MHz,

DMSO-d₆) δ 10.56 (s, 1H, NH-1), 7.76 (dd, J ) 7.69, 8.41 Hz,

1H, H-4), 7.61 (d, J ) 8.79 Hz, 2H, H-2′,6′), 7.49 (s, 1H,

H-vinyl), 6.80 (d, J ) 8.79 Hz, 2H, H-3′,5′), 6.78-6.64 (m, 2H,

H-5,7), 3.01 (s, 6H, N(CH₃)₂-4′); MS m/z (relative intensity, %)

283 (100, [M + 1]^+•). Anal. (C₁₇H₁₅FN₂O) C, H, N.

P r ep a r a tion of (E)-3-[4-(1-F or m ylp ip er a zin -4-yl)ben -

zylid en yl]in d olin -2-on e (16). 4-(1-F or m ylp ip er a zin -4-yl)-

ben za ld eh yd e (11). To a solution of 30 mL (0.3 mol) of

dimethylformamide in 20 mL of anhydrous 1,2-dichloroeth-

ane was added dropwise 30 mL (0.3 mol) of phosphorus

oxychloride at 0 °C. The ice bath was removed. The reac-

tion mixture was stirred for an additional 30 min and cooled

in an ice bath. 1-Phenylpiperazine (16.0 g, 0.1 µmol) was

added to the above solution portionwise over 15 min, and

the reaction mixture was stirred at 50 °C for 1 h. The reac-

tion mixture was poured into ice-cold 1 N sodium hydroxide

solution and stirred at room temperature for 1 h. The or-

ganic layer was separated, and the aqueous layer was ex-

tracted with ethyl acetate. The combined organic layer was

washed with brine until pH ) 7, dried over anhydrous sodium

sulfate, and evaporated. The residue was separated on a silica

gel column eluting with a mixture of ethyl acetate and hexane

to afford 9.0 g (41%) of the title compound as a light-yellow

solid: MS (ES) m/z (relative intensity, %) 217 ([M - 1]^+•, 100);

¹H NMR (360 MHz, DMSO) δ 9.74 (s, 1H), 8.11 (s, 1H), 7.73

(d, J ) 9.1 Hz, 2H), 7.08 (d, J ) 9.1 Hz, 2H), 3.39-3.53 (m,

8H).

cooled to -10 °C, and 2.0 g of N-bromosuccinimide (10 µmol)

was slowly added with stirring. The reaction mixture was

stirred for 1 h at -10 °C and for 2 h at 0 °C. The precipitate

was collected, washed with water, and dried to give 1.9 g

(90%yield) of 5-bromoindolin-2-one.

Syn th esis of 18. The title compound was synthesized from

7 and 4-(1-formylpiperazin-4-yl)benzaldehyde by the same

condensation method described for analogues of 1: ¹H NMR

(360 MHz, DMSO) δ 10.54 (s, 1H, NH-1), 8.04 (s, 1H, H-vinyl),

7.73 (d, J ) 1.87 Hz, 1H, H-4), 7.58 (d, J ) 8.76 Hz, 2H,

H-2′,6′), 7.53 (s, 1H, CHO-4′′), 7.30 (dd, J ) 1.87, 8.27 Hz, 1H,

H-6), 7.05 (d, J ) 8.74 Hz, 2H, H-3′5′), 6.77 (d, J ) 8.27 Hz,

1H, H-7), 3.44-3.48 (m, 2H, H-2′′,6′′), 3.27-3.57 (m, 2H,

H-3′′,5′′). Anal. (C₂₀H₁₈BrN₃O₂) C, H, N.

P r ep a r a tion of (E)-3-[4-(Mor p h olin -4-yl)ben zylid en yl]-

in d olin -2-on e (19). 4-(Mor p h olin -4-yl)ben za ld eh yd e (9).

To a solution of 15 mL of dimethylformamide in 50 mL of 1,2-

dichloroethane was added dropwise 10 mL of phosphorus

oxychloride at 0 °C. The ice bath was removed, and the

reaction mixture was stirred for an additional 30 min. 4-Phe-

nylmorpholine (16.3 g) was added to the above solution

portionwise, and the reaction mixture was refluxed for 2 days.

Triethylamine (2.5 mL) was added to the above reaction

mixture, and the reaction mixture was refluxed for 2 days.

The reaction mixture was poured into ice-cold 1 N sodium

hydroxide solution (pH ) 9 after mixing), and the resulting

mixture was stirred at room temperature for 1 h. The organic

layer was separated, and the aqueous layer was extracted with

2 × 20 mL of dichloromethane. The combined organic layer

was washed with brine until pH ) 7, dried over anhydrous

sodium sulfate, and evaporated. The residue was separated

on a silica gel column eluting with a solvent mixture of ethyl

acetate and hexane to afford 12.95 g (68%) of the title

compound as a white solid.

(E)-3-[4-(Mor ph olin -4-yl)ben zyliden yl]in dolin -2-on e (19).

A reaction mixture of 6.66 g of oxindole, 11.50 g of 9, and 5

mL of piperidine in 50 mL of ethanol was stirred at 90 °C for

5 h. After cooling, the precipitate was filtered, washed with

cold ethanol, and dried to yield 15.0 g (98%) of the title

compound as a yellow solid: ¹H NMR (360 MHz, DMSO-d₆) δ

10.45 (s, 1H, NH-1), 7.74 (d, J ) 7.20 Hz, 1H, H-4), 7.66 (d, J

) 8.98 Hz, 2H, H-2′,6′), 7.54 (s, 1H, H-vinyl), 7.20 (t, J ) 7.20

Hz, 1H, H-6), 7.05 (d, J ) 8.98 Hz, 2H, H-3′,5′), 6.86-6.90 (m,

2H, H-5,7), 3.75 (t, J ) 4.77 Hz, 4H, H-2′′,4′′), 3.28 (t, J )

4.77 Hz, 4H, H-3′′,5′′); MS m/z (relative intensity, %) 307 (100,

[M + 1]^+•). Anal. (C₁₉H₁₈N₂O₂) C, H, N.

(Z)-4-Meth yl-3-[4-(m or p h olin -4-yl)ben zylid en yl]in d o-

lin -2-on e (20): ¹H NMR (360 MHz, DMSO-d₆) δ 10.44 (s, 1H,

NH-1), 8.28 (d, J ) 8.98 Hz, 2H, H-2′,6′), 7.62 (s, 1H, H-vinyl),

7.04 (t, J ) 7.69 Hz, 1H, H-6), 6.96 (d, J ) 8.98 Hz, 2H, H-3′,5′),

6.76 (d, J ) 7.69 Hz, 1H, H-5), 6.68 (d, J ) 7.69 Hz, 1H, H-7),

3.74 (t, J ) 4.98 Hz, 4H, H-2′′,6′′), 3.28 (t, J ) 4.98 Hz, 4H,

H-3′′,5′′), 2.57 (s, 1H, CH₃-4); 2D-NOE ¹H NMR showed the

correlation between, H-vinyl and CH₃-4, which confirmed the

Z conformer; MS m/z (relative intensity, %) 320 (100, M^+•).

Anal. (C₂₀H₂₀N₂O₂) C, H, N.

(E)-5-Ch lor o-3-[4-(m or p h olin -4-yl)b en zylid en yl]in d o-

lin -2-on e (21): ¹H NMR (360 MHz, DMSO-d₆) δ 110.59 (s, 1H,

NH-1), 7.67 (d, J ) 2.33 Hz, 1H, H-4), 7.66 (s, 1H, H-vinyl),

7.62 (d, J ) 9.91 Hz, 2H, H-2′,6′), 7.25 (dd, J ) 2.33, 8.20 Hz,

1H, H-6), 7.09 (d, J ) 9.91 Hz, 2H, H-3′,5′), 6.88 (d, J ) 8.20

Hz, 1H, H-7), 3.74-3.77 (m, 4H, H-2′′,4′′), 3.30-3.33 (m, 4H,

H-3′′,5′′). Anal. (C₁₉H₁₇ClN₂O₂‚0.6H₂O) C, H, N.

(E)-3-[4-(1-F or m ylp ip er a zin -4-yl)ben zylid en yl]in d olin -

2-on e (16). A reaction mixture of 133.15 mg (1 µmol) of

oxindole, 228.3 mg (1.2 µmol) of 11, and 3 drops of piperidine

in 2 mL of ethanol was stirred at 90 °C for 5 h. After the

mixture cooled, the precipitate was filtered, washed with cold

ethanol, and dried to yield 199.5 mg (65%) of the title

compound as a yellow solid: MS (ES) m/z (relative intensity,

1

%) 333 (M^+•, 17); H NMR (360 MHz, DMSO) δ 10.52 (s, 1H,

NH-1), 8.11 (s, 1H, CHO-4′′), 7.75 (d, J ) 7.3 Hz, 1H, H-4),

7.67 (d, J ) 8.7 Hz, 2H, H-2′,6′), 7.55 (s, 1H, H-vinyl), 7.21 (t,

J ) 7.3 Hz, 1H, H-5), 7.10 (d, J ) 8.7 Hz, 2H, H-3′,5′), 6.87-

6.92 (m, 2H, H-6,7), 3.31-3.56 (m, 8H). Anal. (C₂₀H₁₉N₃O₂)

C, H, N.

(Z)-3-[4-(1-For m ylp ip er a zin -4-yl)ben zylid en yl]-4-m eth -

ylin d olin -2-on e (17): ¹H NMR (360 MHz, DMSO) δ 10.42 (s,

1H, NH-1), 8.26 (d, J ) 9.14 Hz, 2H, H-2′,6′), 8.09 (s, 1H,

H-vinyl), 7.60 (s, 1H, CHO-1′), 7.03 (t, J ) 7.75 Hz, 1H, H-6),

7.00 (d, J ) 9.14 Hz, 2H, H-3′,5′), 6.74 (d, J ) 7.75 Hz, 1H,

H-5), 6.66 (d, J ) 7.75 Hz, 1H, H-7), 3.51 (m, 4-H, H-2′,6′),

3.36 (m, 4H, H-3′,5′); MS (ES) m/z (relative intensity, %) 348

(100, [M + 1]^+•). Anal. (C₂₁H₂₁N₃O₂‚0.2H₂O) C, H, N.

(E)-5-Br om o-3-[4-(m or ph olin -4-yl)ben zyliden yl]in dolin -

2-on e (22): ¹H NMR (360 MHz, DMSO-d₆) δ 10.53 (s, br, 1H,

NH-1), 7.73 (d, J ) 1.96 Hz, 1H, H-4), 7.57 (d, J ) 9.25 Hz,

2H, H-2′,6′), 7.53 (s, 1H, H-vinyl), 7.30 (dd, J ) 1.96, 8.33 Hz,

1H, H-6), 7.01 (d, J ) 9.25 Hz, 2H, H-3′,5′), 6.76 (d, J ) 8.33

Hz, 1H, H-7), 3.67 (m, 4H, H-2′′,6′′), 3.25 (m, 4H, H-3′′,5′′);

MS m/z (relative intensity, %) 386 (100, [M + 1]^+•). Anal.

(C₁₉H₁₇BrN₂O₂) C, H, N.

(E)-5-Br om o-3-[4-(1-for m ylpiper azin -4-yl)ben zyliden yl]-

in d olin -2-on e (18). P r ep a r a tion of 5-Br om oin d olin -2-on e

(7). Oxindole (1.3 g, 10 µmol) in 20 mL of acetonitrile was

(Z)-3-[4-(P yr r olidin -1-yl)ben zyliden yl]in dolin -2-on e (23):

¹H NMR (300 MHz, DMSO-d₆) δ 10.46 (s, 1H, NH-1), 8.46 (d,

J ) 9.14 Hz, 2H, H-2′,6′), 7.62 (s, 1H, H-vinyl), 7.61 (d, J )

2600 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14

Sun et al.

8.21 Hz, 1H, H-4), 7.10 (dt, J ) 1.09, 8.21 Hz, 1H, H-6), 6.93

(dt, J ) 1.02, 7.65 Hz, 1H, H-5), 6.79 (d, J ) 7.65 Hz, 1H,

H-7), 6.61 (d, J ) 9.14 Hz, 2H, H-3′,5′), 3.33-3.37 (m, 2H,

H-2′′,5′′), 1.95-2.00 (m, 2H, H-3′′,4′′). Anal. (C₁₉H₁₈N₂O) C,

H, N.

CH(CH₃)₂-3′,5′); MS m/z (relative intensity, %) 356 (100, [M +

1]^+•). Anal. (C₂₁H₂₂ClNO₂) C, H, N.

(E)-3-(3-Br om o-5-ter t-bu tyl-4-m eth oxyben zylid en yl)in -

1

d olin -2-on e (31): H NMR (360 MHz, DMSO-d₆) δ 10.64 (s,

1H, NH-1), 7.84 (d, J ) 2.02 Hz, H-2′), 7.68 (d, J ) 2.02 Hz,

1H, H-6′), 7.54 (s, 1H, H-vinyl), 7.51 (d, J ) 7.69 Hz, 1H, H-4),

7.26 (dt, J ) 1.29, 7.75 Hz, 1H, H-6), 6.85-6.87 (m, 2H, H-5,7),

3.93 (s, 3H, OCH₃-4′), 1.37 (s, 9H, C(CH₃)₃-5′); MS m/z (relative

intensity, %) 388 (100, [M + 2]^+•). Anal. (C₂₀H₂₀BrNO₂‚

0.5H₂O) C, H, N.

Syn th esis of (E)-3-[4-(P ip er id in -1-yl)ben zylid en yl]in -

d olin -2-on e (24). 4-(P ip er id in -1-yl)ben za ld eh yd e (10). To

a solution of 2.3 mL of dimethylformamide in 10 mL of 1,2-

dichloroethane was added dropwise 2.8 mL of phosphorus

oxychloride at 0 °C. The ice bath was removed, and the

reaction mixture was stirred for 15 min. 1-Phenylpiperidine

(3.2 mL) was added to the above solution portionwise, and the

reaction mixture was refluxed overnight. The reaction mixture

was poured into ice-cold 2 N sodium hydroxide solution and

stirred at room temperature for 1 h. The organic layer was

separated, and the aqueous layer was extracted with 2 × 20

mL of ethyl acetate. The combined organic layer was washed

with brine until pH ) 7, dried over anhydrous sodium sulfate,

and evaporated. The residue was separated on a silica gel

column eluting with ethyl acetate and hexane to afford 1.5 g

(40%) of the title compound as a white solid.

(E)-3-[4-(P iper idin -1-yl)ben zyliden yl]in dolin -2-on e (24).

A reaction mixture of 134.0 mg of oxindole, 226.8 g of 10, and

3 drops of piperidine in 2 mL of ethanol was stirred at 90 °C

for 5 h. After the mixture cooled, the precipitate was filtered,

washed with cold ethanol, and dried to yield 268.5 mg (88%)

of the title compound as a yellow solid: ¹H NMR (300 MHz,

DMSO-d₆) δ 10.48 9 (s, 1H, NH-1), 7.77 (d, J ) 7.69 Hz, 1H,

H-4), 7.64 (d, J ) 8.91 Hz, 2H, H-2′,6′), 7.51 (s, 1H, H-vinyl),

7.19 (dt, J ) 1.12, 7.69 Hz, 1H, H-6), 7.03 (d, J ) 8.91 Hz, 2H,

H-3′,5′), 6.89 (dt, J ) 0.78, 7.69 Hz, 1H, H-5), 6.86 (d, J )

7.69 Hz, 1H, H-7), 3.36 (s, br, 4H, CH₂-2′′,6′′), 1.60 (s, br, 6H,

CH₂-3′′,4′′,5′′); MS m/z (relative intensity, %) 305 (100, [M +

1]^+•). Anal. (C₂₀H₂₀N₂O) C, H, N.

(Z)-5-Ch lor o-3-(3-ter t-bu tyl-4-m eth oxyben zylid en yl)in -

1

d olin -2-on e (32): H NMR (360 MHz, DMSO-d₆) δ 10.58 (s,

1H, NH-1), 8.53 (d, J ) 2.13 Hz, 1H, H-2′), 8.41 (dd, J ) 2.13,

8.44 Hz, 1H, H-6′), 7.89 (s, 1H, H-vinyl), 7.81 (d, J ) 2.22 Hz,

1H, H-4), 7.18 (dd, J ) 2.22, 8.26 Hz, 1H, H-6), 7.10 (d, J )

8.44 Hz, 1H, H-5′), 6.81 (d, J ) 8.26 Hz, 1H, H-7), 3.90 (s, 3H,

OCH₃-4′), 1.35 (s, 9H, C(CH₃)₃-3′); MS m/z (relative intensity,

%) 342 (100, M^+•). Anal. (C₂₀H₂₀ClNO₂) C, H, N.

(E)-3-(4-Isop r op ylben zylid en yl)in d olin -2-on e (2): ¹H

NMR (300 MHz, DMSO-d₆) δ 10.57 (s, 1H, NH-1), 7.59-7.65

(m, 4H, H-4,vinyl,2′,6′), 7.38 (d, J ) 8.49 Hz, 2H, H-3′,5′), 7.21

(dt, J ) 0.91, 7.82 Hz, 1H, H-6), 6.83-6.88 (m, 2H, H-5,7),

2.94 (h, J ) 6.99 Hz, 1H, CH(CH₃)₂-4′), 1.23 (d, J ) 6.99 Hz,

6H, CH(CH₃)₂-4′); MS m/z (relative intensity, %) 264 (100, [M

+ 1]^+•). Anal. (C₁₈H₁₇NO) C, H, N.

(E)-3-(3,5-Diisop r op yl-4-h yd r oxyben zylid en yl)in d olin -

2-on e (33): ¹H NMR (300 MHz, DMSO-d₆) δ 10.54 (s, 1H,

NH-1), 8.87 (s, br, 1H, OH-4′), 7.74 (d, J ) 7.47 Hz, 1H, H-4),

7.58 (s, 1H, H-vinyl), 7.45 (s, 2H, H-2′,6′), 7.20 (dt, J ) 1.10,

8.37 Hz, 1H, H-6), 6.88 (d, J ) 7.47 Hz, 1H, H-5), 6.87 (dt, J

) 1.03, 8.37 Hz, 1H, H-7), 3.37 (m, 2H, CH(CH₃)₂-3′,5′), 1.20

(d, J ) 6.77 Hz, 12H, CH(CH₃)₂-3′,5′). Anal. (C₂₁H₂₃NO₂) C,

H, N.

(E)-3-(4-Hyd r oxyben zylid en yl)in d olin -2-on e (25): ¹H

NMR (360 MHz, DMSO-d₆) δ 10.46 (s, 1H, NH-1), 10.06 (s,

br, 1H, OH-4′), 7.69 (d, J ) 7.52 Hz, 1H, H-4), 7.62 (d, J )

8.54 Hz, 2H, H-2′,6′), 7.54 (s, 1H, H-vinyl), 7.21 (dt, J ) 1.09,

7.52 Hz, 1H, H-6), 6.86-6.93 (m, 4H, H-3′,5′,5,7); MS m/z

(E)-3-(3-ter t-Bu t yl-4-m et h oxyb en zylid en yl)in d olin -2-

1

on e (34): H NMR (360 MHz, DMSO-d₆) δ 10.50 (s, 1H, NH-

1), 7.66 (d, J ) 7.82 Hz, 1H, H-4), 7.58-7.62 (m, 3H, H-vinyl

and H-2′,6′), 7.20 (t, J ) 7.65 Hz, 1H, H-6), 7.13 (d, J ) 8.26

Hz, 1H, H-5′), 6.84-6.88 (m, 2H, H-5,7), 3.89 (s, 3H, OCH₃-

4′), 1.35 (s, 9H, C(CH₃)₃-3′); MS m/z (relative intensity, %) 308

(100, [M + 1]^+•). Anal. (C₂₀H₂₁NO₂) C, H, N.

(relative intensity, %) 238 (100, [M + 1]^+•). Anal. (C₁₅H₁₁

NO₂) C, H, N.

-

(E)-3-(4-Meth oxyben zylid en yl)in d olin -2-on e (26): ¹H

NMR (360 MHz, DMSO-d₆) δ 10.48 (s, 1H, NH-1), 7.69 (d, J

) 8.82 Hz, 2H, H-2′,6′), 7.64 (d, J ) 7.55 Hz, 1H, H-4), 7.57 (s,

1H, H-vinyl), 7.20 (t, J ) 7.55 Hz, 1H, H-6), 7.08 (d, J ) 8.82

Hz, 2H, H-3′,5′), 6.83-6.88 (m, 2H, H-5,7), 3.83 (s, 3H, OCH₃-

4′); MS m/z (relative intensity, %) 252 (100, [M + 1]^+•). Anal.

(C₁₆H₁₃NO₂) C, H, N.

(E)-3-(4-Br om oben zyliden yl)in dolin -2-on e (27): ¹H NMR

(300 MHz, DMSO-d₆) δ 10.61 (s, 1H, NH-1), 7.70 (d, J ) 8.63

Hz, 2H, H-2′,6′), 7.63 (d, J ) 8.63 Hz, 2H, H-3′,5′), 7.55 (s,

1H, H-vinyl), 7.47 (d, J ) 7.58 Hz, 1H, H-4), 7.22 (t, J ) 7.58

Hz, 1H, H-6), 6.81-6.87 (m, 2H, H-5,7); MS m/z (relative

intensity, %) 300 (100, M^+•). Anal. (C₁₅H₁₀BrNO‚0.3H₂O) C,

H, N.

(E)-3-(4-Ca r boxyben zylid en yl)in d olin -2-on e (28): ¹H

NMR (360 MHz, DMSO-d₆) δ 13.08 (s, br, 1H, COOH-4′), 10.61

(s, br, 1H, NH-1), 8.07 (d, J ) 8.06 Hz, 2H), 7.80 (d, J ) 8.06

Hz, 2H), 7.65 (s, 1H, H-vinyl), 7.45 (d, J ) 7.51 Hz, 1H, H-4),

7.25 (dt, J ) 0.94, 7.53 Hz, 1H, H-6), 6.83-6.90 (m, 2H, H-5,7).

Anal. (C₁₆H₁₁NO₃‚0.125H₂O) C, H, N.

(E)-3-(3,5-Di-ter t-bu tyl-4-h yd r oxyben zyliden yl)in dolin -

2-on e (29): ¹H NMR (360 MHz, DMSO-d₆) δ 10.43 (s, 1H, NH-

1), 7.58 (s, 1H, H-vinyl), 7.57 (d, J ) 6.80 Hz, 1H, H-4), 7.53

(s, 2H, H-2′,6′), 7.19 (t, J ) 6.80 Hz, 1H, H-6), 6.85-6.89

(m, 2H, H-5,7), 1.41 (s, 18H, C(CH₃)₃-3′,5′); MS m/z (rela-

tive intensity, %) 350 (100, [M + 1]^+•). Anal. (C₂₃H₂₇NO₂) C,

H, N.

(Z)-3-(4-Br om oben zyliden yl)-1-m eth ylin dolin -2-on e (35):

¹H NMR (300 MHz, DMSO-d₆) δ 8.33 (d, J ) 8.56 Hz, 2H,

H-2′,6′), 7.83 (s, 1H, H-vinyl), 7.75 (d, J ) 7.42 Hz, 1H, H-4),

7.67 (d, J ) 8.56 Hz, 2H, H-3′,5′), 7.33 (t, J ) 7.42 Hz, 1H,

H-6), 7.07 (t, J ) 7.70 Hz, 1H, H-5), 7.00 (d, J ) 7.70 Hz, 1H,

H-7), 3.20 (s, 3H, NCH₃-1); MS m/z (relative intensity, %) 315

(100, [M + 1]^+•). Anal. (C₁₆H₁₂BrNO) C, H, N.

(E)-3-(3-Br om o-5-ter t-bu tyl-4-m eth oxyben zylid en yl)-5-

1

ch lor oin d olin -2-on e (36): H NMR (360 MHz, DMSO-d₆) δ

10.70 (s, 1H, NH-1), 8.83 (d, J ) 2.15 Hz, 1H, H-2′), 8.38 (d, J

) 2.15 Hz, 1H, H-6′), 7.90 (s, 1H, H-vinyl), 7.82 (d, J ) 1.97

Hz, 1H, H-4), 7.30 (dd, J ) 1.97, 8.16 Hz, 1H, H-6), 6.83 (d, J

) 8.16 Hz, 1H, H-7), 3.92 (s, 3H, OCH₃-4′), 1.39 (s, 9H,

C(CH₃)₃-3′); MS m/z (relative intensity, %) 420 (100, M^+•). Anal.

(C₂₀H₁₉BrClNO₂) C, H, N.

(E)-3-[1-[4-(P ip er id in -1-yl)p h en yl]eth ylid en yl]in d olin -

2-on e (37). The reaction mixture of 142.3 mg of pyrrolidine

(2.0 µmol) and 243.9 mg of 4-(piperidin-1-yl)phenylacetone (1.2

µmol) was refluxed for 1 h in toluene. A Dean-Stark trap

filled with anhydrous sodium sulfate was used to remove

water. Oxindole (133.0 mg, 1.0 µmol) was added to the above

mixture, and the reaction mixture was stirred for an additional

5 h. Toluene was removed by a rotary pump, and the residue

was separated on a silica gel column eluting with ethyl acetate

1

and hexane to give 63.0 mg of the title compound (20%); H

NMR (360 MHz, DMSO-d₆) δ 10.43 (s, 1H, NH-1), 7.21 (d, J

) 8.70 Hz, 2H, H-2′,6′), 7.04 (dt, J ) 1.27, 7.72 Hz, 1H, H-6),

7.01 (d, J ) 8.70 Hz, 2H, H-3′,5′), 6.76 (d, J ) 7.72 Hz, 1H,

H-7), 6.59 (dt, J ) 1.12, 7.72 Hz, 1H, H-5), 6.44 (d, J ) 7.72

Hz, 1H, H-4), 3.25 (t, J ) 5.39 Hz, 4H, CH₂-2′′,6′′), 2.66 (s,

3H, CH₃-vinyl), 1.59-1.64 (m, 6H, CH₂-3′′,4′′,5′′). MS m/z

(relative intensity, %) 319 (100, [M + 1]^+•). Anal. (C₂₁H₂₂N₂O‚

0.6H₂O) C, H, N.

(E)-3-(3,5-Diisopr opyl-4-h ydr oxyben zyliden yl)-5-ch lor o-

in d olin -2-on e (30): ¹H NMR (300 MHz, DMSO-d₆) δ 10.64

(s, 1H, NH-1), 8.94 (s, br, 1H, OH-4′), 7.73 (d, J ) 1.96 Hz,

1H, H-4), 7.66 (s, 1H, H-vinyl), 7.45 (s, 2H, H-2′,6′), 7.26 (dd,

J ) 1.96, 8.36 Hz, 1H, H-6), 6.89 (d, J ) 8.36 Hz, 1H, H-7),

3.31-3.42 (m, 2H, CH(CH₃)₂-3′,5′), 1.21 (d, J ) 6.51 Hz, 12H,

Synthesis, Evaluation of 3-Substituted Indolinones

J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2601

Gen er a l P r oced u r e for 3-[(Su bstitu ted p yr r olyl)m eth -

ylid en yl]in d olin -2-on e An a logu es (Com p ou n d 3 An a -

logu es). A reaction mixture of the proper oxindole (indolin-

2-one) (1 equiv), the appropriate aldehyde (1.2 equiv), and

piperidine (0.1 µmol) in ethanol (1-2 mL/1 µmol oxindole) was

stirred at 90 °C for 3-5 h. After the mixture cooled, the

precipitate was filtered, washed with cold ethanol, and dried

to give the target compound in over 80% yield. The analytical

data reported here belongs to the major isomer. The data for

the minor isomer is not reported. The ratios of Z to E isomers

for each compound are shown in Tables 2-6.

7.14 (m, 2H, H-6,5′), 6.98 (dt, J ) 0.84, 7.59 Hz, 1H, H-5), 6.87

(d, J ) 7.59 Hz, 1H, H-7), 3.60 (s, 3H, CH₂CH₂COOCH₃-3′),

2.69 (t, J ) 7.29 Hz, 2H, CH₂CH₂COOCH₃-4′), 2.56 (t, J ) 7.29

Hz, 2H, CH₂CH₂COOCH₃-3′), 2.26 (s, 3H, CH₃-4′); MS m/z

(relative intensity, %) 311 (56, [M + 1]^+•). Anal. (C₁₈H₁₈N₂O₃)

C, H, N.

(Z)-3-[[3-(Eth oxyca r bon yl)-4-m eth ylp yr r ol-5-yl]m eth -

ylid en yl]in d olin -2-on e (44): ¹H NMR (300 MHz, DMSO-d₆)

δ 13.81 (s, br, 1H, NH-1′), 11.04 (s, br, 1H, NH-1), 7.84-7.85

(m, 2H, H-4,2′), 7.72 (s, 1H, H-vinyl), 7.18 (dt, J ) 1.34, 7.70

Hz, 1H, H-6), 7.02 (dt, J ) 1.02, 7.70 Hz, 1H, H-5), 6.90 (d, J

) 7.70 Hz, 1H, H-7), 4.22 (q, J ) 7.05 Hz, COOCH₂CH₃-3′),

2.54 (s, 3H, CH₃-4′), 1.29 (t, J ) 7.05 Hz, 3H, COOCH₂CH₃-

3′); MS m/z (relative intensity, %) 297 (100, [M + 1]^+•). Anal.

(C₁₇H₁₆N₂O₃) C, H, N.

(Z)-3-[(2,4-Dim eth ylp yr r ol-5-yl)m eth ylid en yl]in d olin -

2-on e (45). A reaction mixture of 134.0 mg of oxindole, 147.8

mg of the 3,5-dimethylpyrrole-2-carboxaldehyde, and 3 drops

of piperidine in 2 mL of ethanol was stirred at 90 °C for 3 h.

After the mixture cooled, the precipitate was filtered, washed

with cold ethanol, and dried to yield 136.7 mg (57%) of the

title compound as a yellow solid: ¹H NMR (300 MHz, DMSO-

d₆) δ 13.36 (s, br, 1H, NH-1′), 10.77 (s, 1H, NH-1), 7.71 (d, J )

7.70 Hz, 1H, H-4), 7.55 (s, 1H, H-vinyl), 7.09 (dt, J ) 1.24,

7.70 Hz, 1H, H-6), 6.97 (dt, J ) 0.97, 7.70 Hz, 1H, H-5), 6.87

(d, J ) 7.66 Hz, 1H, H-7), 6.00 (d, J ) 2.25 Hz, 1H, H-3′), 2.32

(s, 3H, CH₃-4′(2′)), 2.30 (s, 3H, CH₃-2′(4′)); MS m/z (rela-

tive intensity, %) 239 (100, [M + 1]^+•). Anal. (C₁₅H₁₄N₂O) C,

H, N.

1

(Z)-3-[(P yr r ol-2-yl)m eth ylid en yl]in d olin -2-on e (3): H

NMR (360 MHz, DMSO-d₆) δ 13.34 (s, br, 1H, NH-1′), 10.83

(s, 1H, NH-1), 7.71 (s, 1H, H-vinyl), 7.61 (d, J ) 7.68 Hz, 1H,

H-4), 7.33 (s, br, 1H, H-5′), 7.14 (t, J ) 7.68 Hz, 1H, H-6), 6.98

(t, J ) 7.68 Hz, 1H, H-5), 6.88 (d, J ) 7.68 Hz, 1H, H-7), 6.83

(t, J ) 1.71 Hz, 1H, H-3′), 6.33-6.36 (m, 1H, H-4′); MS m/z

(relative intensity, %) 211 (100, [M + 1]^+•). Anal. (C₁₃H₁₀N₂O)

C, H, N.

(Z)-4-Met h yl-3-[(p yr r ol-2-yl)m et h ylid en yl]in d olin -2-

1

on e (38): H NMR (360 MHz, DMSO-d₆) δ 13.50 (s, br, 1H,

NH-1′), 10.87 (s, 1H, NH-1), 7.65 (s, 1H, H-vinyl), 7.32 (d, J )

1.68 Hz, 1H, H-3′), 7.05 (t, J ) 7.76 Hz, 1H, H-6), 6.91 (t, J )

1.63 Hz, 1H, H-5′), 6.80 (d, J ) 7.66 Hz, 1H, H-7), 6.76 (t, J )

7.76 Hz, 1H, H-5), 6.33-6.36 (m, 1H, H-4′), 2.57 (s, 3H, CH₃-

4); MS m/z (relative intensity, %) 247 (100, [M + Na]^+•). Anal.

(C₁₄H₁₂N₂O₃‚0.1H₂O) C, H, N.

(Z)-5-Ch lor o-3-[(p yr r ol-2-yl)m et h ylid en yl]in d olin -2-

1

on e (39): H NMR (360 MHz, DMSO-d₆) δ 13.30 (s, br, 1H,

NH-1′), 10.93 (s, 1H, NH-1), 7.86 (s, 1H, H-vinyl), 7.74 (d, J )

2.27 Hz, 1H, H-4), 7.38-7.40 (m, 1H, H-5′), 7.16 (dd, J ) 2.27,

8.28 Hz, 1H, H-6), 6.88 (d, J ) 8.28 Hz, 1H, H-7), 6.85 (dd, J

) 1.59, 3.44 Hz, 1H, H-3′), 6.37-6.39 (m, 1H, H-4′); MS m/z

(relative intensity, %) 245 (100, M^+•). Anal. (C₁₃H₉N₂OCl) C,

H, N.

(Z)-6-F lu or o-3-[(p yr r ol-2-yl)m et h ylid en yl]in d olin -2-

on e (40): ¹H NMR (360 MHz, DMSO-d₆) δ 13.19 (s, 1H, NH-

1′), 10.98 (s, 1H, NH-1), 7.69 (s, 1H, H-vinyl), 7.61 (dd, J )

5.47, 8.34 Hz, 1H, H-4), 7.32-7.33 (m, 1H, H-5′), 6.76-6.82

(m, 2H, H-5,3′), 7.69 (dd, J ) 2.31, 9.19 Hz, 1H, H-7), 6.33-

6.35 (m, 1H, H-4′); MS m/z (relative intensity, %) 229 (100,

[M + 1]^+•). Anal. (C₁₃H₉FN₂O) C, H, N.

(Z)-3-[(3,4-Dim eth ylp yr r ol-2-yl)m eth ylid en yl]in d olin -

2-on e (41). A reaction mixture of 67.0 mg of oxindole, 73.0

mg of the 3,4-dimethylpyrrole-2-carboxaldehyde, and 2 drops

of piperidine in 2 mL of ethanol was stirred at 90 °C for 3 h.

After the mixture cooled, the precipitate was filtered, washed

with cold ethanol, and dried to yield 87.7 mg (37%) of the title

compound as a yellow solid: ¹H NMR (300 MHz, DMSO-d₆) δ

13.28 (s, br, 1H, NH-1′), 10.82 (s, 1H, NH-1), 7.75 (d, J ) 7.62

Hz, 1H, H-4), 7.62 (s, 1H, H-vinyl), 7.09-7.14 (m, 2H, H-6,5′),

6.98 (dt, J ) 1.03, 7.62 Hz, 1H, H-5), 6.87 (d, J ) 7.62 Hz, 1H,

H-7), 2.25 (s, 3H, CH₃-4′), 2.02 (s, 3H, CH₃-3′); MS m/z (rela-

tive intensity, %) 239 (100, [M + 1]^+•). Anal. (C₁₅H₁₄N₂O) C,

H, N.

(Z)-3-[(3-(2-Ca r b oxyet h yl)-4-m et h ylp yr r ol-2-yl)m et h -

ylid en yl]in d olin -2-on e (42). A reaction mixture of 134.0 mg

(1.0 µmol) of oxindole, 217.43 mg (1.2 µmol) of the 3-(2-

carboxyethyl)-4-methylpyrrole-2-carboxaldehyde, and 3 drops

of piperidine in 3 mL of ethanol was stirred at 90 °C for 3 h.

After the mixture cooled, the precipitate was filtered, washed

with cold ethanol, and dried to yield 172.4 mg (58%) of the

title compound as a yellow solid: ¹H NMR (300 MHz, DMSO-

d₆) δ 13.27 (s, 1H, CH₂CH₂COOH-3′), 10.84 (s, br, 1H, NH-1),

7.67-7.70 (m, 2H, H-4, vinyl), 7.08-7.13 (m, 2H, H-6,5′), 6.97

(dt, J ) 0.99, 7.47 Hz, 1H, H-5), 6.86 (d, J ) 7.47 Hz, 1H,

H-7), 2.92 (t, J ) 7.37 Hz, 2H, CH₂CH₂COOH-3′), 2.32 (t, J )

7.37 Hz, 2H, CH₂CH₂COOH-3′), 2.03 (s, 3H, CH₃-4′); MS m/z

(relative intensity, %) 297 (100, [M + 1]^+•). Anal. (C₁₇H₁₆N₂O₃)

C, H, N.

(Z)-6-Flu or o-3-[(2,4-dim eth ylpyr r ol-5-yl)m eth yliden yl]-

in d olin -2-on e (46): ¹H NMR (300 MHz, DMSO-d₆) δ 13.19

(s, br, 1H, NH-1′), 10.85 (s, 1H, NH-1), 7.00 (dd, J ) 5.48, 8.38

Hz, 1H, H-4), 7.52 (s, 1H, H-vinyl), 6.74-6.79 (m, 1H, H-5),

6.67 (dd, J ) 2.43, 9.17 Hz, 1H, H-7), 5.98 (d, J ) 2.41 Hz,

1H, H-3′), 2.30 (s, 3H, CH₃-2′), 2.23 (s, 3H, CH₃-4′); MS m/z

(relative intensity, %) 257 (100, [M + 1]^+•). Anal. (C₁₅H₁₃

-

FN₂O) C, H, N.

(Z)-3-[(3-Eth yl-2,4-d im eth ylp yr r ol-5-yl)m eth ylid en yl]-

in d olin -2-on e (47). P r ep a r a tion of 3,5-Dim eth yl-4-eth -

ylp yr r ole-2-ca r boxa ld eh yd e (13). To a solution of 2.3 mL

(30 mol) of dimethylformamide in 50 mL of anhydrous 1,2-

dichloroethane was added dropwise 2.8 mL (30 mol) of

phosphorus oxychloride at 0 °C. The ice bath was removed.

The reaction mixture was further stirred for 30 min, and cooled

with ice bath. 2,5-Dimethyl-4-ethylpyrrole (2.46 g, 20 µmol)

was added to the above solution portionwise, and the reaction

mixture was stirred at 50 °C for 3 h. The reaction mixture

was poured into ice-cold 1 N sodium hydroxide solution and

stirred at room temperature for 2 h. The gray precipitate was

filtered and washed with water to a pH of 7. The solid was

dried in an oven overnight to give 13 (2.42 g, 80%): ¹H NMR

(360 MHz, DMSO) δ 11.33 (s, br, 1H, CHO-2), 9.42 (s, 1H, NH-

1), 2.38 (q, J ) 7.55 Hz, 2H, CH₂CH₃-4), 2.20 (s, 3H, CH₃-3),

2.15 (s, 3H, CH₃-5), 0.99 (t, J ) 7.55 Hz, 3H, CH₂CH₃-4).

P r ep a r a tion of 47. Condensation of 13 with oxindole using

the same procedure for analogues of 3 gave 47: ¹H NMR (360

MHz, DMSO-d₆) δ 13.38 (s, br, 1H, NH-1′), 10.69 (s, 1H, NH-

1), 7.69 (d, J ) 7.34 Hz, 1H, H-4), 7.54 (s, 1H, H-vinyl), 7.07

(dt, J ) 1.12, 7.34 Hz, 1H, H-6), 6.96 (dt, J ) 1.07, 7.34 Hz,

1H, H-5), 6.86 (d, J ) 7.34 Hz, 1H, H-7), 2.40 (q, J ) 7.61 Hz,

2H, CH₂CH₃-3′), 2.29 (s, 3H, CH₃-2′(4′)), 2.25 (s, 3H, CH₃-4′-

(2′)), 1.04 (t, J ) 7.61 Hz, 3H, CH₂CH₃-3′); MS m/z (rela-

tive intensity, %) 267 (100, [M + 1]^+•). Anal. (C₁₇H₁₈N₂O) C,

H, N.

(Z)-3-[(2,4-Dim et h yl-3-(et h oxyca r b on yl)p yr r ol-5-yl)-

m eth ylid en yl]in d olin -2-on e (48). A reaction mixture of

134.0 mg of oxindole, 234.3 mg of 4-(ethoxycarbonyl)-3,5-

dimethylpyrrole-2-carboxaldehyde, and 3 drops of piperidine

in 3 mL of ethanol was stirred at 90 °C for 3 h. After the

mixture cooled, the precipitate was filtered, washed with cold

ethanol, and dried to yield 244.6 mg (79%) of the title

compound as a yellow solid: ¹H NMR (300 MHz, DMSO-d₆) δ

13.88 (s, br, 1H, NH-1′), 10.95 (s, br, 1H, NH-1), 7.80 (d, J )

7.53 Hz, 1H, H-4), 7.62 (s, 1H, H-vinyl), 7.15 (dt, J ) 1.10,

(Z)-3-[[3-(2-(Meth oxyca r bon yl)eth yl)-4-m eth ylp yr r ol-

5-yl]m eth ylid en yl]in d olin -2-on e (43): ¹H NMR (360 MHz,

DMSO-d₆) δ 13.31 (s, br, 1H, NH-1′), 10.78 (s, br, 1H, NH-1),

7.74 (d, J ) 7.59 Hz, 1H, H-4), 7.61 (s, 1H, H-vinyl), 7.09-

2602 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14

Sun et al.

7.53 Hz, 2H, H-6), 7.00 (dt, J ) 1.06, 7.53 Hz, 1H, H-5), 6.89

(d, J ) 7.53 Hz, 1H, H-7), 4.21 (q, J ) 7.32 Hz, 2H,

COOCH2CH3-3′), 2.54 (s, 3H, CH₃-4′(2′)), 2.49 (s, 3H, CH₃-

2′(4′)), 1.30 (t, J ) 7.32 Hz, 3H, COOCH₂CH₃-3′); MS m/z

(relative intensity, %) 311 (100, [M + 1]^+•). Anal. (C₁₈H₁₈N₂O₃)

C, H, N.

(Z)-3-[(4-Eth yl-2,3-d im eth ylp yr r ol-5-yl)m eth ylid en yl]-

in d olin -2-on e (49): ¹H NMR (360 MHz, DMSO-d₆) δ 13.39

(s, br, 1H, NH-1′), 10.69 (s, 1H, NH-1), 7.69 (d, J ) 7.67 Hz,

1H, H-4), 7.52 (s, 1H, H-vinyl), 7.07 (dt, J ) 1.11, 7.67 Hz,

1H, H-6), 6.96 (dt, J ) 1.17, 7.67 Hz, 1H, H-5), 6.86 (d, J )

7.67 Hz, 1H, H-7), 2.70 (q, J ) 7.47 Hz, 2H, CH₂CH₃-4′), 2.27

(s, 3H, CH₃-2′(3′)), 1.97 (s, 3H, CH₃-3′(2′)), 1.11 (t, J ) 7.47

Hz, 3H, CH₂CH₃-4′); MS m/z (relative intensity, %) 267 (100,

[M + 1]^+•). Anal. (C₁₇H₁₈N₂O) C, H, N.

(Z)-3-[(2-(Meth ylth io)th ien -5-yl)m eth ylid en yl]in d olin -

2-on e (56). A reaction mixture of 134.0 mg of oxindole, 189.9

mg of the 5-(methylthio)thiophene-2-carboxaldehyde, and 3

drops of piperidine in 2 mL of ethanol was stirred at 90 °C for

3 h. After cooling, the precipitate was filtered, washed with

cold ethanol, and dried to yield 246.6 mg (90%) of the title

compound as an orange solid: ¹H NMR (360 MHz, DMSO-d₆)

δ 10.56 (s, br, 1H, NH-1), 7.98 (s, 1H, H-vinyl), 7.73 (d, J )

4.28 Hz, 1H, H-4′(3′)), 7.64 (d, J ) 7.54 Hz, 1H, H-4), 7.19 (dt,

J ) 1.11, 7.54 Hz, 1H, H-6), 7.13 (d, J ) 4.28 Hz, 1H, H-3′-

(4′)), 6.98 (dt, J ) 0.75, 7.54 Hz, 1H, H-5), 6.85 (d, J ) 7.54

Hz, 1H, H-7), 2.64 (s, 3H, SCH₃-2′); MS m/z (relative intensity,

%) 274 (100, [M + 1]^+•). Anal. (C₁₄H₁₁NOS₂) C, H, N.

(Z)-4-Meth yl-3-[(2-(m eth ylth io)th ien -5-yl)m eth yliden yl]-

in d olin -2-on e (57): ¹H NMR (300 MHz, DMSO-d₆) δ 10.60

(s, br, NH-1), 7.87 (s, 1H, H-vinyl), 7.76 (d, J ) 4.33 Hz, 1H,

H-4′), 7.12 (d, J ) 4.33 Hz, 1H, H-3′), 7.08 (t, J ) 7.92 Hz, 1H,

H-6), 6.78 (d, J ) 7.92 Hz, 1H, H-5), 6.72 (d, J ) 7.92 Hz, 1H,

H-7), 2.63 (s, 3H, SCH₃-2′), 2.57 (s, 3H, CH₃-4); 2D-NOE ¹H

NMR showed the correlation between H-vinyl and CH₃-4,

which confirmed the Z conformer; MS m/z (relative inten-

sity, %) 310 (100, [M + Na]^+•). Anal. (C₁₅H₁₃NOS₂‚0.1H₂O)

C, H, N.

(Z)-3-[(1-Met h ylp yr r ol-5-yl)m et h ylid en yl]in d olin -2-

1

on e (50): H NMR (360 MHz, DMSO-d₆) δ 10.45 (s, 1H, NH-

1), 7.98 (d, J ) 7.38 Hz, 1H, H-4), 7.47 (s, 1H, H-vinyl), 7.17-

7.22 (m, 2H, H-6,5′), 7.05 (dd, J ) 0.88, 3.82 Hz, 1H, H-3′),

6.95 (dt, J ) 1.08, 7.38 Hz, 1H, H-5), 6.88 (d, J ) 7.38 Hz, 1H,

H-7), 6.31 (dd, J ) 2.73, 3.82 Hz, 1H, H-4′), 3.78 (s, 3H, NCH₃-

1′); MS m/z (relative intensity, %) 225 (100, [M + 1]^+•). Anal.

(C₁₄H₁₂N₂O) C, H, N.

(Z)-5-Nit r o-3-[(p yr r ol-2-yl)m e t h ylid e n yl]in d olin -2-

on e (51): H NMR (360 MHz, DMSO-d₆) δ 13.16 (s, br, 1H,

(E)-3-[(2-(Eth ylth io)th ien -5-yl)m eth ylid en yl]in d olin -2-

on e (58): H NMR (360 MHz, DMSO-d₆) δ 10.52 (s, 1H, NH-

1

NH-1′), 11.49 (s, 1H, NH-1), 8.58 (d, J ) 2.10 Hz, 1H, H-4),

8.14 (s, 1H, H-vinyl), 8.08 (dd, J ) 2.10, 8.51 Hz, 1H, H-6),

7.47 (dd, J ) 2.67, 3.66 Hz, 1H, H-5′), 7.05 (d, J ) 8.51 Hz,

1H, H-7), 6.97-6.98 (m, 1H, H-3′), 6.42-6.44 (m, 1H, H-4′);

MS m/z (relative intensity, %) 255 (100, M^+•). Anal.

(C₁₃H₉N₃O₃‚0.1H₂O) C, H, N.

(Z)-4-Meth yl-3-[(2,4-dim eth ylpyr r ol-5-yl)m eth yliden yl]-

in d olin -2-on e (52): ¹H NMR (360 MHz, DMSO-d₆) δ 10.75

(s, br, NH-1), 7.51 (s, 1H, H-vinyl), 7.00 (t, J ) 7.65 Hz, 1H,

H-6), 6.79 (d, J ) 7.93 Hz, 1H, H-5), 6.75 (d, J ) 7.93 Hz, 1H,

H-7), 6.01 (d, J ) 2.81 Hz, 1H, H-3′), 2.57 (s, 3H, CH₃-4),

2.32 (s, 3H, CH₃-2′), 2.24 (s, 3H, CH₃-4′); MS m/z (relative

intensity, %) 253 (100, [M + 1]^+•). Anal. (C₁₆H₁₆N₂O‚0.3H₂O)

C, H, N.

(Z)-5-Meth yl-3-[(2,4-dim eth ylpyr r ol-5-yl)m eth yliden yl]-

in d olin -2-on e (53). P r ep a r a tion of 5-Meth ylin d olin -2-

on e (8). 5-Methylisatin (15.0 g, 10.2 µmol) and 60 mL of

hydrazine hydrate were heated to 140-160 °C for 4 h. The

reaction mixture was cooled to room temperature, poured into

300 mL of ice water, and acidified to pH 2 with 6 N

hydrochloric acid. After standing at room temperature for 2

days the precipitate was collected by vacuum filtration, washed

with water, and dried under vacuum to give 6.5 g (47% yield)

of 5-methylindolin-2-one: ¹H NMR (360 MHz, DMSO-d₆) δ

10.19 (s, 1H, NH-1), 6.98 (s, 1H, H-4), 6.94 (d, J ) 8.11 Hz,

1H, H-6), 6.68 (d, J ) 8.11 Hz, 1H, H-7), 3.39 (s, 2H, CH₂-3),

and 2.22 (s, 3H, CH₃-5).

Syn th esis of 53. The title compound was prepared in the

same way as 3 as described above: ¹H NMR (300 MHz, DMSO-

d₆) δ 13.35 (s, br, 1H, NH-1′), 10.64 (s, 1H, NH-1), 7.52 (s, 1H,

H-4), 7.49 (s, 1H, H-vinyl), 6.89 (d, J ) 7.72 Hz, 1H, H-6), 6.73

(d, J ) 7.72 Hz, 1H, H-7), 5.98 (d, J ) 1.91 Hz, 1H, H-3′), 2.29

(s, 9H, CH₃-5,2′,4); MS m/z (relative intensity, %) 253 (100,

[M + 1]^+•). Anal. (C₁₆H₁₆N₂O) C, H, N.

1), 7.98 (s, 1H, H-vinyl), 7.76 (d, J ) 3.92 Hz, 1H, H-4′(3′)),

7.64 (d, J ) 7.40 Hz, 1H, H-4), 7.17 (dt, J ) 1.13, 7.40 Hz, 1H,

H-6), 6.95-6.99 (m, 2H, H-5,3′(4′)), 6.84 (d, J ) 7.40 Hz, 1H,

H-7), 2.90 (q, J ) 7.49 Hz, 2H, CH₂CH₃-2), and 1.29 (t, J )

7.49 Hz, 3H, CH₂CH₃-2); MS m/z (relative intensity, %) 256

(100, [M + 1]^+•). Anal. (C₁₅H₁₃NOS) C, H, N.

(E)-3-[(F u r a n -2-yl)m eth ylid en yl]in d olin -2-on e (59): ¹H

NMR (360 MHz, DMSO-d₆) δ 10.58 (s, 1H, NH-1), 8.35 (d, J

) 7.55 Hz, 1H, H-4), 8.13 (d, J ) 1.87 Hz, 1H, H-5′), 7.33 (s,

1H, H-vinyl), 7.22-7.26 (m, 2H, H-6,3′), 7.00 (dt, J ) 1.08,

7.55 Hz, 1H, H-5), 6.87 (d, J ) 7.59 Hz, 1H, H-7), 6.78 (dd, J

) 1.87, 3.11 Hz, H-4′); MS m/z (relative intensity, %) 212 (100,

[M + 1]^+•). Anal. (C₁₃H₉NO₂) C, H, N.

(E )-3-[(2-Me t h ylfu r a n -5-yl)m e t h ylid e n yl]in d olin -2-

1

on e (60): H NMR (360 MHz, DMSO-d₆) δ 10.48 (s, 1H, NH-

1), 8.29 (d, J ) 7.78 Hz, 1H, H-4), 7.24 (s, 1H, H-vinyl), 7.22

(t, J ) 7.67 Hz, 1H, H-6), 7.15 (d, J ) 3.28 Hz, 1H, H-4′), 7.01

(t, J ) 7.78 Hz, 1H, H-5), 6.86 (d, J ) 7.67 Hz, 1H, H-7), 6.44

(d, J ) 3.28 Hz, 1H, H-3′), 2.51 (s, 3H, CH₃-2′); MS m/z (rela-

tive intensity, %) 226 (100, [M + 1]^+•). Anal. (C₁₄H₁₁NO₂) C,

H, N.

(E)-3-[(2-E t h ylfu r a n -5-yl)m et h ylid en yl]in d olin -2-on e

(61): ¹H NMR (360 MHz, DMSO-d₆) δ 10.49 (s, 1H, NH-1),

8.31 (d, J ) 7.68 Hz, 1H, H-4), 7.25 (s, 1H, H-vinyl), 7.21 (dt,

J ) 1.08, 7.60 Hz, 1H, H-6), 7.15 (d, J ) 3.16 Hz, 1H, H-4′),

7.00 (dt, J ) 1.08, 7.68 Hz, 1H, H-5), 6.86 (d, J ) 7.60 Hz, 1H,

H-7), 6.45 (d, J ) 3.16 Hz, 1H, H-3′), 2.85 (q, J ) 7.49 Hz, 2H,

CH₂CH₃-2′), 1.29 (t, J ) 7.49 Hz, 3H, CH₂CH₃-2′); MS m/z

(relative intensity, %) 240 (100, [M + 1]^+•). Anal. (C₁₅H₁₃

NO₂) C, H, N.

-

(Z)-3-[(4-Ch lor op yr a zol-3-yl)m et h ylid en yl]in d olin -2-

1

on e (62): H NMR (360 MHz, DMSO-d₆) δ 14.59 (s, 1H, NH-

1′), 11.26 (s, 1H, br, NH-1), 7.86-7.88 (m, 2H, H-4,5′), 7.53 (s,

1H, H-vinyl), 7.30 (dt, J ) 1.03, 7.74 Hz, 1H, H-6), 7.07 (dt, J

) 1.02, 7.74 Hz, 1H, H-5), and 6.94 (d, J ) 7.74 Hz, 1H, H-7);

MS m/z (relative intensity, %) 246 (100, M^+•). Anal. (C₁₂H₈-

ClN₃O) C, H, N.

(Z)-3-[(3-Br om ot h ie n -2-yl)m e t h ylid e n yl]in d olin -2-

1

on e (54): H NMR (300 MHz, DMSO-d₆) δ 10.72 (s, 1H, NH-

1), 8.00 (d, J ) 5.62 Hz, 1H, H-4′(5′)), 7.82 (s, 1H, H-vinyl),

7.65 (d, J ) 7.61 Hz, 1H, H-4), 7.35 (d, J ) 5.62 Hz, 1H, H-5′-

(4′)), 7.26 (dt, J ) 1.03, 7.61 Hz, 1H, H-6), 7.02 (dt, J ) 0.84,

7.61 Hz, 1H, H-5), 6.88 (d, J ) 7.61 Hz, 1H, H-7); MS m/z

(relative intensity, %) 306 (43, M^+•). Anal. (C₁₃H₈BrNOS) C,

H, N.

(E)-3-[(4-Ch lor o-1-m et h ylp yr a zol-3-yl)m et h ylid en yl]-

in d olin -2-on e (63): ¹H NMR (360 MHz, DMSO-d₆) δ 10.57

(s, 1H, NH-1), 8.88 (d, J ) 7.57 Hz, 1H, H-4), 8.19 (s, 1H,

H-vinyl), 7.34 (s, 1H, H-5′), 7.28 (dt, J ) 1.14, 7.57 Hz, 1H,

H-6), 7.02 (dt, J ) 1.07, 7.57 Hz, 1H, H-5), 6.87 (d, J ) 7.57

Hz, 1H, H-7), 4.05 (s, 3H, CH₃-1′); MS m/z (relative intensity,

%) 260 (100, M^+•). Anal. (C₁₃H₁₀ClN₃O) C, H, N.

(Z)-3-[(3-Br om ot h ie n -5-yl)m e t h ylid e n yl]in d olin -2-

1

on e (55): H NMR (300 MHz, DMSO-d₆) δ 10.70 (s, 1H, NH-

1), 8.04 (s, 1H, H-vinyl), 7.95-7.97 (m, 2H, H-2′,4′), 7.59 (d, J

) 7.57 Hz, 1H, H-4), 7.23 (dt, J ) 1.10, 7.57 Hz, 1H, H-6),

7.01 (dt, J ) 0.87, 7.57 Hz, 1H, H-5), 6.87 (d, J ) 7.57 Hz, 1H,

H-7); MS m/z (relative intensity, %) 306 (100, M^+•). Anal.

(C₁₃H₈BrNOS) C, H, N.

Ack n ow led gm en t. The authors would like to thank

Brian Dowd and Sarah Shimer for screening all of the

compounds against various RTKs and Congxin Liang

Synthesis, Evaluation of 3-Substituted Indolinones

J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2603

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for valuable discussions on the cocrystal structures of

inhibitor-FGFR catalytic domain.

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(20) Compound 45 has been named as either 3-[(2,4-dimethylpyrrol-

5-yl)methylidenyl]indolin-2-one or 3-[(3,5-dimethylpyrrol-2-yl)-

methylidenyl]indolin-2-one in this paper and other presenta-

tions. However, the wrong name, 3-[(2,3-dimethylpyrrol-5-

yl)methylidenyl]indolin-2-one, was given in our patent (PCT Int.

Appl. 293pp, WO 9807695).

J M980123I

Article Doi

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

DOI: 10.1021/jm980123i

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Article abstract of DOI:10.1021/jm980123i

Full text of DOI:10.1021/jm980123i

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