II. Synthesis and biological evaluation of some bioisosteres and congeners of the antitumor agent, 2-{4-[(7-chloro-2-quinoxalinyl)oxylphenoxy}propionic acid (XK469)

Article abstract of DOI:10.1021/jm0200097

XK469 (1) is among the most highly and broadly active antitumor agents to have been evaluated in our laboratories. Subsequent developmental studies led to the entry of (R)-(+) 1 (NSC 698215) into phase 1 clinical trials (NIH UO1-CA62487). The antitumor me

Full text of DOI:10.1021/jm0200097

3130
J . Med. Chem. 2002, 45, 3130-3137
II. Syn th esis a n d Biologica l Eva lu a tion of Som e Bioisoster es a n d Con gen er s of
th e An titu m or Agen t, 2-{4-[(7-Ch lor o-2-qu in oxa lin yl)oxy]p h en oxy}p r op ion ic
Acid (XK469)
Stuart T. Hazeldine,† Lisa Polin,† J uiwanna Kushner,† Kathryn White,† Nicole M. Bouregeois,‡ Brianna Crantz,‡
Eduardo Palomino,§ Thomas H. Corbett,† and J erome P. Horwitz*,†,‡
Department of Internal Medicine, Division of Hematology and Oncology, Wayne State University School of Medicine,
Barbara Ann Karmanos Cancer Institute, and Walker Cancer Research Institute
Received J anuary 7, 2002
XK469 (1) is among the most highly and broadly active antitumor agents to have been evaluated
in our laboratories. Subsequent developmental studies led to the entry of (R)-(+) 1 (NSC 698215)
into phase 1 clinical trials (NIH UO1-CA62487). The antitumor mechanism of action of 1
remains to be elucidated, which has prompted a sustained effort to elaborate a pharmacophoric
pattern of 1. The present study focused on a strategy of synthesis and biological evaluation of
topologically based, bioisosteric replacements of the quinoxaline moiety in the lead compound
(1) by quinazoline (4a -d ), 1,2,4-benzotriazine (12a -18b), and quinoline (21a -g) ring systems.
The synthetic approach to each of the bioisosteres of 1 utilized the methodology developed in
previous work (see Hazeldine, S. T.; Polin, L.; Kushner, J .; Paluch, J .; White, K.; Edelstein,
M.; Palomino, E.; Corbett, T. H.; Horwitz, J . P. Design, Synthesis, and Biological Evaluation
of Analogues of the Antitumor Agent 2-{4-[(7-Chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid
(XK469). J . Med. Chem. 2001, 44, 1758-1776.), which is extended to the procurement of the
benzoxazole (23a ,b), benzthiazole (23c,d ), pyridine (25a ,b), and pyrazine (27) congeners of 1.
Only quinoline analogues, bearing a 7-halo (21a ,b,d ,e) or a 7-methoxy substituent (21g), showed
antitumor activities (Br > Cl > CH3O > F ≈ I), at levels comparable to or greater than the
range of activities manifested by 1 and corresponding analogues. At high individual dosages,
the (S)-(-) enantiomers of 1 and 21b,d all produce a reversible slowing of nerve-conduction
velocity in the mice, the onset of which is characterized by a distinctive dysfunction of the
hind legs, causing uncoordinated movements. The condition resolves within 5-10 min. However,
at higher dosages, which approach a lethal level, the behavior extended to the front legs, lasting
from 20 min to 1 h. By contrast, the (R)-(+) forms of these same agents did not induce the
phenomenon of slowing of nerve-conduction velocity.
In tr od u ction
Compound 1 (XK469) (Figure 1) is among the most
highly and broadly active antitumor agents to have been
evaluated in our laboratories.1-4 Subsequent develop-
mental studies involved the National Cancer Institute
F igu r e 1.
(NCI), the DuPont Pharmaceuticals Company (DPC),
and our laboratories. The collaborative effort led only
recently to the entry of (R)-(+) 1 (NSC 698215) into
phase 1 clinical trials (NIH UO1-CA62487). The mech-
anism of action of 1 remains unknown, though several
common mechanisms of anticancer drug action have
been excluded.1a In the absence of a validated molecular
target, efforts were initiated to develop a pharmaco-
phoric pattern,1a,b to delineate the supramolecular
interactions of 1 with a putative biological target. It was
found1 that changes in the nature and location of
substituents in ring A of 1 induced significant differ-
ences in both the in vitro and the in vivo activities of
the 2-{4-[(2-quinoxalinyl)oxy]phenoxy)propionic acids.
Thus, the 7-halogen derivatives proved to be the most
active compounds exhibiting an order of relative anti-
tumor activity of F ≈ Cl ≈ Br > I, whereas the 3-, 5-,
6-, and 8-regioisomers of 1 were essentially all inactive.
All alterations of the hydroquinone (1,4) connector
linkage in 1 resulted in inactive compounds. By con-
trast, simple alkyl ester and amide derivatives of 1
showed only minor reductions in activity relative to that
of the free acid. The second phase of this effort to
elaborate a pharmacophore of 1 focused on a classical
strategy of systematic generation and biological evalu-
ation of topologically based, bioisosteric replacement of
the quinoxaline moiety in the lead compound by quinazo-
line, 1,2,4-benzotriazine, and quinoline ring systems,
which was extended to the congeneric benzoxazole,
benzthiazole, pyrazine, and pyridine derivatives.
Ch em istr y
Qu in a zolin es. There is considerable patent litera-
ture that describes the preparation of a wide spectrum
of heterocyclic, ether type, phenoxy fatty acids, including
the bioisosteric structures listed above, which comprise
an important group of herbicides for the selective control
of weed grasses. The synthetic methodology leading to
these agents, which was utilized extensively in our prior
* To whom correspondence should be addressed. Tel: 313-833-0715.
Fax: 313-831-7518. E-mail: horwitz@kci.wayne.edu.
† Wayne State University School of Medicine.
‡ Barbara Ann Karmanos Cancer Institute.
§ Walker Cancer Research Institute.
10.1021/jm0200097 CCC: $22.00 © 2002 American Chemical Society
Published on Web 06/12/2002

Bioisosteres and Congeners of the Agent XK469
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 14 3131
Sch em e 1a
a
Reagents: (a) K2CO3/CH3CN; (b) aqueous NaOH/THF; (c) aqueous HCl; (d) K2CO3/butanone; (e) HCO2NH4/Pd-C/CH3OH; (e) H2/
Pd-C/CH3OH; (f) K2CO3/DMF.
work1a and is quite straightforward, is highlighted in
Schemes 1 and 2. Thus, the etherification of methyl 2-(4-
hydroxyphenoxy)propionate (3) with each of the 2,5-,
2,6-, 2,7-, and 2,8-dichloroquinazolines (Scheme 1, 2a -
d ) was achieved with K2CO3 in acetonitrile2 to provide
the corresponding methyl 2-{4-[(5-, 6-, 7-, and 8-chloro-
2-quinazolinyl)oxy]phenoxy}propionates in good yields.
Hydrolysis of the latter with dilute NaOH, followed by
acidification, gave the propionic acid derivatives (4a -
d ). The precursory dichloroquinazolines (2a -d ) were
prepared via the following known sequence of reac-
tions: (i) selective photolytic (side chain) dichloronation
of the corresponding (commercially available) chloro-o-
tolylisocyanates to the benzal chloride derivatives;3 (ii)
conversion of the latter with anhydrous NH3 to N-
substituted ureas; and (iii) cyclization of each urea with
NH4OH to a chloro-2-quinazolone.4 The latter, on treat-
ment with POCl3, gave the dichloroquinazolines.
anilines, according to the methods of Wolf and Pfister.5a,b
Processes for the preparation of substituted 2-{4-[(1-
oxide-1,2,4-benzotriazin-3-yl)oxy]phenoxy}propionate es-
ters have also been described.6 For example, the reaction
of 3-chloro-1,2,4-benzotriazine-1-oxide (5) and 3, under
the conditions outlined in Scheme 1, provided methyl
2-{4-[(1-oxide-1,2,4-benzotriazin-3-yl)oxy]phenoxy}pro-
pionate (12a ).6 Reduction (HCO2NH4/Pd-C/MeOH) of
the latter yielded methyl 2-{4-[(1,2,4-benzotriazin-3-yl)-
oxy]phenoxy}propionate (12b),6 which, on saponification
and acidification, afforded the unsubstituted 1,2,4-
triazine derivative, 12c. As noted above, simple alkyl
(e.g., methyl and ethyl) esters differ only marginally in
activity ratings from the free carboxylic acid. Moreover,
if an ester failed to show activity, the acid also proved
to be inactive. In accord with these findings, neither
12a -c nor 13a -c manifested significant antitumor
activities (Table 1), which negated the need to saponify
the methyl propionate esters 14b-18b.
1,2,4-Ben zot r ia zin es. Synthesis of the precursory
3-chloro-1,2,4-benzotriazines-1-oxide (Scheme 1, 5-11)
proceeded from correspondingly substituted 2-nitro-
Qu in olin es. The synthesis of a series of 2-{4-[(6- and
7-m on os u bs t it u t ed -2-qu in olin yl)oxy]p h en oxy}-

3132 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 14
Hazeldine et al.
Sch em e 2a
a
Reagents: (a) K2CO3/CH3CN; (b) aqueous NaOH/THF; for 22a , aqueous K2CO3/THF; (c) aqueous HCl; (d) K2CO3/DMF.
Ta ble 1. Evaluation of Selected Analogues of 1 Against Solid Tumors of Mice
no. of
% body
wt. loss at
nadir
regressions
complete
(partial)
enantiomeric
form
injections total dose
drug
deaths
T/C
(%)
log tumor
cell killa
activity
compd no.
SC tumor
IV
(mg/kg)
curesa ratinga
1 (Pos Cont)
1 (Pos Cont)
21a
21b
21b
21b
21c
21d
21d
21e
21f
21g
21g
23a
23b
racemic
R-(+)
racemic
R-(+)
Mam17/Adr*
Panc 03**
Mam17/Adr*
Panc 03**
Panc 03*
Mam17/Adr*
13
7
7
7
7
364
560
324
560
336
300
0/5
0/7
0/5
0/7
0/5
0/5
0
10.3
24.5
14
14.1
0
0
2.82
2.0
1.5
2.3
2.6
3.8
0/5
0/7
0/5
0/7
0/5
0/5
++++
+++
++
+++
+++
++++
+2.5
-1.6
+3.7
-8.9
-10.6
0/7
0/7 (2/7)
racemic
racemic
racemic
R-(+)
racemic
racemic
racemic
racemic
racemic
racemic
racemic
6
insufficient cytotoxcity in culture, not tested in mice
Panc 03**
Mam17/Adr*
Mam17/Adr*
6
6
7
480
352
370
0/4
0/5
0/5
+5.9
-5.5
-4.0
2.8
0
2
3/4
0/5
3.1
4.2
2.1
0/4
0/5
0/5
++++
++++
++
insufficient cytotoxcity in culture, not tested in mice
Mam17/Adr*
Panc 03**
Mam17/Adr*
Mam17/Adr*
6
5
7
7
450
450
462
455
0/5
0/5
0/4
0/3
-5.0
-2.0
-2.3
0
0
45
>100
>100
3.0
0.8
none
none
0/5
0/5
0/4
0/3
++++
+
inactive
inactive
a
See Experimental Section; *, early; **, advanced.
propionic acids (21a -g) is highlighted in Scheme 1.
Several examples of these have been previously de-
scribed in the patent literature in context with the
design of novel herbicides.7 Preparations of intermedi-
ates 7-methoxy-, 7-methyl-, 6-, and 7-chloro-2-quinolinol
have been described by Effenberger and Hartmann,8
whereas syntheses of 7-bromo-2-quinolinol were re-
ported by Campbell et al.9a,b The methodology, employed
by the latter group, was applied successfully to the
preparation of both the 7-fluoro- and 7-iodo-2-chloro-
quinolines. Wherein preparations of (R)-(+) 21b and
21d were required (Table 1), racemic 20 was replaced
with the commercially available (R)-(+) enantiomer to
provide the corresponding product in >99% enantio-
meric excess.
Six-Mem ber ed Heter oa r yl Der iva tives. Prepara-
tions of selected pyrazine and pyridine analogues of 1
were carried out to ascertain the relative importance
of a fused benzene ring to the biological activities of 1
and correspondingly substituted quinoline derivatives.
Preparations of both 2-{4-[(5- and 6-chloro-substituted-
2-pyridyl)oxy]phenoxy}propionic acids (Scheme 2, 25a ,b,
respectively) are the subjects of patents in the herbicide
literature13,14 and are described as well as antiinflam-
matory and analgesic agents.15 Interaction of the com-
mercially available 2,5- and 2,6-dichloropyridines (24a,b,
respectively) with 20 (Scheme 2) with K2CO3 in di-
methyl formamide (DMF), followed by acidification,
provided the corresponding 2-propionic acid derivatives,
25a ,b, respectively. The more reactive electrophilic
2-position of 2,6-dichloropyrazine (26) permitted the
same displacement reaction with 3 to be carried out with
K2CO3 in refluxing acetonitrile. Saponification of the
intermediate ester, followed by acidification, gave the
2-pyrazinyloxy derivative (27).
Six F ive-Mem b er ed H et er oa r yl Der iva t ives.
Preparations of structures 23a -d (Scheme 2), in which
A is O or S, have been described in herbicidal patent
literature for the selective control of weed grasses, e.g.,
23b, Fenoxaprop.10 Processes for the preparation of the
intermediates 2,5-(22a ) and 2,6-dichlorobenzoxazole
(22b) are readily accessible11 as is 2,5-dichlorobenzthia-
zole12 (22c). 2,6-Dichlorobenzthiaziole (22d ) is com-
mercially available.
Biologica l Resu lts a n d Discu ssion
All newly synthesized analogues of 1 were initially
evaluated, as previously described,1a in our in vitro, disk

Bioisosteres and Congeners of the Agent XK469
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 14 3133
diffusion soft agar colony formation assay, to determine
cytotoxicity against leukemias, solid tumors, and normal
cells (see the Experimental Section). None of the quinazo-
line, 1,2,4-benzotriazine, pyrazine, or pyridine congeners
of 1 manifested sufficient activity in culture to warrant
testing in mice. In sharp contrast, the 7-haloquinolines
(21a ,b,d ,e) all exhibited impressive antitumor activities
(Table 1). Interestingly, the 7-bromo derivative (21d )
proved to be the most active, eliciting three out of four
complete regressions (CRs) and a 3.1 log kill against
advanced stage pancreatic ductal adenocarcinoma 03.
On the other hand, the 7-chloro compound (21b) pro-
duced no CRs but a 2.3 log kill against the same tumor.
Similarly, 1, in the same trial, effected no CRs and a
2.0 log kill. In an evaluation against resistant mammary
adenocarcinoma-17/adr (M17/adr, a p-glycoprotein posi-
tive, multiresistant tumor), 21d gave rise to a 4.2 log
kill. Bioisostere 21a , though active (1.5 log kill) against
M17/adr, proved to be inferior to both 21b and 21d . The
relative antitumor activities of the 2-{4-[(7-halo-2-
quinoxalinyl)oxy]phenoxy}propionic acids1a were found
to be F ≈ Cl ≈ Br > I, whereas the corresponding
quinoline derivatives showed an order of activity of Br
> Cl > F ≈ I. The 7-methoxy quinoline analogue (21g)
was also highly active (3.0 log kill) against M17/adr.
However, activity fell off rapidly with dose reduction
(62%), producing only a 1.4 log kill. Despite the limited
testing performed to date, the effect of 7-methoxy
substitution is noteworthy in that the antitumor effects
parallel those of the 7-methoxy analogue of 1. Both the
6-chloro (21c) and the 7-methyl (21f) derivatives showed
insufficient cytotoxicity in culture to warrant testing in
mice. The congeneric benzoxazole derivatives (23a ,b)
indicated modest in vitro activity but failed to exhibit
meaningful cytotoxic results (Table 1) in the treatment
of mice bearing M17/Adr. The pyridines (25a ,b) and
pyrazine (27) congeners failed to show activity in
culture.
prompted the selection of the (R)-(+) form of 1 for phase
1 trials.
Su m m a r y
The second phase of an effort1 to elaborate a phar-
macophore of 1 focused on a strategy of synthesis and
biological evaluation of topologically based, bioisosteric
replacements of the quinoxaline moiety in the lead
compound 1 by quinazoline, 1,2,4-benzotriazine, and
quinoline ring systems. The study was extended to
include the congeneric benzoxazole, benzthiazole, pyra-
zine, and pyridine derivatives. Only the quinoline
analogues bearing a 7-halo or a 7-methoxy substituent
showed levels of antitumor activities (Br > Cl > CH3O
> F ≈ I), comparable to or greater than those mani-
fested by 1 and corresponding analogues.
It is apparent, then, that the interchange of the N4
and C3 atoms of the quinoxaline moiety in 1 to generate
a 7-chloroquinazoline derivative (4c) or the replacement
of the C3 in the quinoxaline ring of 1 by N3 to form a
1,2,4-triazine ring analogue (13c) produce, in both cases,
inactive compounds. By contrast, the exchange of N4 in
1 by C4 generated a group of quinoline antitumor agents
(21a ,b,d ,e,g) of at least equal activity.
The failure of either the pyridine (25a ,b) or the
pyrazine analogues (27) to manifest cytotoxicity points
to the importance, relative to antitumor activity, of a
7-halo- or 7-methoxybenzene moiety of the quinoxaline
and quinoline ring systems of 1 and 21a ,b ,d ,e,g,
respectively. On the other hand, there is at present no
ready explanation of the modest, in vitro activity of the
benzoxazoles (23a ,b) and lack of activity noted for the
benzthiazole derivatives (23c,d ).
At high individual dosages, the S-(-) enantiomers of
1 and 21b,d each produce a reversible slowing of nerve-
conduction velocity in mice, which resolves within 5-10
min. This phenomenon is not observed with correspond-
ing R-(+) enantiomers and is also absent in R-(+) 1.
Toxicit y Differ en ces Am on g E n a n t iom er s a n d
Ra cem ic Mixtu r es. The cumulative long term dose-
limiting toxicity for all of the active agents (21b,d and
1) was the same: gastrointestinal (GI) epithelial dam-
age, with only minor marrow toxicity.16 However, sub-
stantial differences were observed in the immediate
(∼15 s to 1 h), post-IV injection effects of the enanti-
omers of 21b,d and 1. At high individual dosages, the
(S)-(-) enantiomers produce a reversible slowing of
nerve conduction velocity in the mice. This precipitated
a distinctive dysfunction of the hind legs, which folded
backward, causing uncoordinated movements, preclud-
ing, thereby, support of the mouse. The condition
resolved within 5-10 min; however, at higher dosages
(approaching a lethal level), the behavior extended to
the front legs, lasting from 20 min to 1 h. During
recovery, the problem in the movement of the front legs
vanished before the hind legs, indicating that the longer
nerves were more affected than the shorter nerves. By
contrast, the (R)-(+) forms of these same agents did not
induce the observed aberrant behavior. It is important
to point out that interconversion of the (R)-(+) and (S)-
(-) enantiomers of 1 has been reported to occur in
plasma of mice and higher animals with >90% existing
in the (R)-(+) form at equilibrium.17 These findings
Exp er im en ta l Section
Ch em istr y. All commercially available solvents and re-
agents were used without further purification. Fenoxaprop was
obtained from the Fluka Chemical Corp. (U.S.A.). Melting
points were determined on a Thomas-Hoover melting point
apparatus and are uncorrected. Infrared spectra were mea-
sured on a Perkin-Elmer 1330 spectrometer in KBr pellets or
as a thin film. Optical rotations were measured on a J asco
DIP-370 polarimeter at room temperature. Nuclear magnetic
resonance (1H and 13C NMR) spectra were recorded at room
temperature and referenced to a residual solvent signal on
either a Varian Unity 300, Varian Mercury 400, or GE Q300
instruments in the Department of Chemistry, Wayne State
University, Detroit, MI. Chemical shifts are reported in parts
per million downfield from tetramethylsilane (TMS). The
splitting pattern abbreviations are as follows: s, singlet; d,
doublet; t, triplet; q, quartet; b, broad; m, unresolved multiplet.
Mass spectra were recorded on a MS80RFA instrument and
other instruments at Wayne State University. Flash column
chromatography was carried out with silica gel 200-400 mesh,
60 Å (Aldrich), and the crude product was introduced on to
the column as a CHCl3 solution. Thin-layer chromatography
was performed on Whatman PE SIL G/UV (250 µm) plates.
Compounds were visualized by use of 254 or 366 nm light and
I2 vapor. Elemental analyses were performed by M-H-W
Laboratories, Phoenix, AZ.

3134 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 14
Hazeldine et al.
Gen er a l Meth od of P r ep a r a tion of Ester s of Qu in a zo-
lin es, 1,2,4-Ben zotr ia zin es-1-oxid es, Ben zoxa zoles, Ben z-
th ia zoles, a n d P yr a zin es. A mixture of the 2- or 3-chloro-
hetrocycle, 3, anhydrous K2CO3, and an aprotic solvent (CH3-
CN or butanone) was refluxed until the reaction was complete.
The hot mixture was filtered, the residue was washed with
warm acetone, and the filtrate was evaporated to dryness. The
residue was dissolved in CH2Cl2, filtered through silica gel,
and washed with ether. The filtrate was shaken with saturated
NaCl, containing a small amount of 1 N NaOH, followed by
saturated NaCl. The dried solution (MgSO4) was evaporated,
and the crude residue was purified by flash column chroma-
tography where required, followed by crystallization from a
mixture of AcOEt-hexanes (heptane).
Gen er a l Meth od P r ep a r a tion of th e Red u ced of 1,2,4-
Ben zotr ia zin es-1-oxid e Ester s. Meth od A. A mixture of the
1-oxide derivative, HCO2NH4, Pd-C, and CH3OH was refluxed
until the reaction was complete. The solvent was evaporated,
and the residue was mixed with hot AcOEt. The mixture was
filtered through silica gel, the filtrate was evaporated, and the
residue was purified by flash column chromatography. The
product was crystallized from a mixture of AcOEt-hexanes
(heptane).
Meth od B. A mixture of the 1-oxide, 2% Pd-C, and CH3-
OH was shaken with H2 in a Parr apparatus until the reaction
was complete. The catalyst was removed, and the filtrate was
then concentrated and purified by flash column chromatog-
raphy. The product crystallized from a mixture of AcOEt-
hexanes (heptane).
Gen er a l P r oced u r e for Hyd r olysis of Ca r boxylic Acid
Ester s. To a solution of the ester dissolved in tetrahydrofuran
(THF) was added, in portions, 0.1 N base, and the mixture
was stirred overnight at room temperature. The reaction
mixture was concentrated, filtered to remove insoluble mate-
rial, and then cooled and adjusted to pH 3-4 with 0.25 N HCl.
The solid that deposited on further cooling was collected, wash-
ed with ice-water, dried, and crystallized from aqueous eth-
anol. The benzoxazoles and benzthiazoles were crystallized
from a mixture of AcOEt-hexanes. Attempts to crystallize the
1,2,4-benzotriazine derivatives resulted in significant decom-
position.
P r ep a r a t ion of Qu in olin e a n d P yr id in e Ca r b oxylic
Acid s. A mixture of the 2-chlorohetrocycle, 20, anhydrous
base, and DMF was gently refluxed until the reaction was
complete. After it was cooled, the reaction mixture was
concentrated, water was then added, and the solution was
filtered through Celite to remove insoluble material. After it
was cooled, the filtrate was acidified with 1 N HCl to pH 3-4,
and the solid was collected, washed with ice-water, and dried
or extracted with AcOEt. The impure product was dissolved
in AcOEt and filtered through silica gel to remove the dark,
very polar contaminant. The filtrate was then concentrated,
purified by flash column chromatography (if required), and
crystallized from a mixture of AcOEt-hexanes (heptane).
P r ep a r a t ion of t h e 2-Ch lor o-6- a n d 7-Su b st it u t ed
Qu in olin es. Cyclization of the precursory E-(N)-(3-substituted
phenyl)-3-ethoxypropenamides with an electron-withdrawing
substituent (F, Cl, Br, and I) was effected in concentrated H2-
SO4,12,13 whereas cyclization of those bearing an electron-
donating substituent (CH3 and CH3O) was effected in concen-
trated HCl12 to give a mixture of isomeric 2-quinolinols (see
ratios below). Treatment of the crude mixture with POCl3
provided corresponding mixtures of the 2-chloroquinolines. The
2-chloro-7-substituted quinolines (19a ,b,d -g) were obtained
after removal of dark polar contaminants by filtering the latter,
dissolved in CHCl3 through silica gel. Fractional crystallization
of the mixture of solids from 2-propanaol removed the 5-sub-
stituted isomers, providing thereby 19a ,b,d -g.
and 5-fluoro-2-quinolinols in a ratio of 92:8. The product 19a
was obtained, as described above, in the form of white crystals;
1
mp 102-103 °C. H NMR (400 MHz, CDCl3): δ 8.08 (d, J )
8.0 Hz, 1H), 7.81 (dd, J ) 9.2, 6.4 Hz, 1H), 7.65 (dd, J ) 9.6,
2.4 Hz, 1H), 7.38-7.31 (m, 2H).
2,7-Dich lor oqu in olin e (19b). Cyclization of E-(N)-(3-chlo-
rophenyl)-3-ethoxypropenamide gave a mixture of 7- and
5-chloro-2-quinolinols in a ratio of 70:30. The product 19b was
obtained, as described above, in the form of white crystals;
1
mp 121-123 °C. H NMR (300 MHz, CDCl3): δ 8.09 (d, J )
8.7 Hz, 1H), 8.02 (d, J ) 1.8 Hz, 1H), 7.76 (d, J ) 8.7 Hz, 1H),
7.52 (dd, J ) 8.7, 2.1 Hz, 1H), 7.39 (d, J ) 8.7 Hz, 1H).
2,6-Dich lor oqu in olin e (19c). Cyclization of E-(N)-(4-chlo-
rophenyl)-3-ethoxypropenamide gave 6-chloro-2-quinolinol,
which in turn provided 19c as white crystals; mp 162-163
°C. 1H NMR (300 MHz, CDCl3): δ 8.03 (d, J ) 8.7 Hz, 1H),
7.96 (d, J ) 9.0 Hz, 1H), 7.80 (d, J ) 1.8 Hz, 1H), 7.68 (dd, J
) 8.7, 2.1 Hz, 1H), 7.42 (d, J ) 8.7 Hz, 1H).
7-Br om o-2-ch lor oqu in olin e (19d ). Cyclization of E-(N)-
(3-bromophenyl)-3-ethoxypropenamide gave a mixture of 7-
and 5-bromo-2-quinolinol in a ratio of 63:37. The desired
product 19d was obtained as white crystals; mp 120-121 °C.
1H NMR (400 MHz, CDCl3): δ 8.20 (d, J ) 1.6 Hz, 1H), 8.07
(d, J ) 8.0 Hz, 1H), 7.69 (d, J ) 8.0 Hz, 1H), 7.65 (dd, J ) 8.8,
1.6 Hz, 1H), 7.40 (d, J ) 8.8 Hz, 1H).
2-Ch lor o-7-iod oqu in olin e (19e). Cyclization of E-(N)-(3-
iodophenyl)-3-ethoxypropenamide gave a mixture of 7- and
5-iodo-2-quinolinols in a ratio of 57:43. The product 19e was
obtained as light yellow crystals; mp 122-123 °C. 1H NMR
(400 MHz, CDCl3): δ 8.43 (d, J ) 1.6 Hz, 1H), 8.05 (d, J ) 9.2
Hz, 1H), 7.81 (dd, J ) 8.4, 1.6 Hz, 1H), 7.51 (d, J ) 9.2 Hz,
1H), 7.39 (d, J ) 8.0 Hz, 1H).
2-Ch lor o-7-m eth ylqu in olin e (19f). Cyclization of E-(N)-
(3-methylphenyl)-3-ethoxypropen-amide gave a mixture of 7-
and 5-methyl-2-quinolinols in a ratio of 55:45. The product 19f
1
was obtained as white crystals; mp 83-84 °C. H NMR (400
MHz, CDCl3): δ 8.05 (d, J ) 8.0 Hz, 1H), 7.80 (s, 1H), 7.70 (d,
J ) 8.0 Hz, 1H), 7.39 (dd, J ) 8.0, 1.6 Hz, 1H), 7.32 (d, J )
8.8 Hz, 1H), 2.56 (s, 3H).
2-Ch lor o-7-m eth oxyqu in olin e (19g). Cyclization of E-(N)-
(3-methoxyphenyl)-3-ethoxypropenamide gave a mixture of 7-
and 5-methoxy-2-quinolinols in a ratio of 82:18. The desired
product, 19g, was obtained as off-white crystals; mp 99-100
°C. 1H NMR (400 MHz, CDCl3): δ 8.01 (d, J ) 8.0 Hz, 1H),
7.68 (d, J ) 8.8 Hz, 1H), 7.35 (d, J ) 2.8 Hz, 1H), 7.25 (d, J )
8.0 Hz, 1H), 7.20 (dd, J ) 9.2, 2.4 Hz, 1H), 3.93 (s, 3H).
2-{4-[(7-F lu or o-2-q u in olin yl)oxy]p h en oxy}p r op ion ic
Acid (21a ). A mixture of 19a (0.18 g, 1.0 mmol), 20 (0.19 g,
1.0 mmol), anhydrous K2CO3 (0.35 g, 2.5 mmol), and DMF (5
mL) were refluxed overnight. The pure product (0.20 g, 61%
yield) was obtained after crystallization from AcOEt-heptane
as white crystals; mp 135-137 °C. 1H NMR (400 MHz, DMSO-
d6): δ 13.08 (bs, 1H), 8.38 (d, J ) 8.8 Hz, 1H), 7.99 (dd, J )
8.8, 6.4 Hz, 1H), 7.40-7.32 (m, 2H), 7.18 (d, J ) 8.8 Hz, 1H),
7.17-7.12 (m, 2H), 6.94-6.89 (m, 2H), 4.82 (q, J ) 6.8 Hz,
1H), 1.51 (d, J ) 6.4 Hz, 3H). 13C NMR (100 MHz, DMSO-d6):
δ 173.9, 163.6 (d, J ) 245.5 Hz), 163.2, 155.2, 147.6 (d, J )
12.7 Hz), 147.3, 141.0, 130.8 (d, J ) 10.4 Hz), 123.4, 123.2,
116.1, 115.1 (d, J ) 24.5 Hz), 112.7, 111.7 (d, J ) 20.8 Hz),
72.5, 19.0. 19F NMR (376 MHz, CDCl3): δ 76.33 (m). IR
(KBr): 3415 (OH), 1710 (CdO) cm-1. MS (EI): m/z (%) 327
(M+, 59), 282 (15), 268 (15), 254 (67), 238 (8), 226 (4), 209 (4),
198 (3), 151 (5), 146 (100), 126 (12), 119 (7), 91 (7). HRMS
(EI): m/z 327.0910 (M+, calcd for C18H14NFO4, 327.0907). Anal.
(C18H14NFO4) C, H, N.
2-{4-[(7-Ch lor o-2-q u in olin yl)oxy]p h en oxy}p r op ion ic
Acid (21b). Quinoline 19b (1.15 g, 5.81 mmol), 20 (1.06 g, 5.81
mmol), anhydrous K2CO3 (2.00 g, 14.5 mmol), and DMF (25
mL) were refluxed overnight. Pure material (1.68 g, 84% yield)
was obtained after crystallization from AcOEt-heptane as
Cyclization of E-(N)-(4-chlorophenyl)-3-ethoxypropenamide
in concentrated H2SO4 provided 6-chloro-2-quinolinol, which
was then converted and isolated as described above to 2,6-
dichloroquinoline (19c).
2-Ch lor o-7-flu or oqu in olin e (19a ). Cyclization of E-(N)-
(3-fluorophenyl)-3-ethoxy-propenamide gave a mixture of 7-
1
white crystals; mp 149-150 °C. H NMR (400 MHz, DMSO-
d6): δ 13.05 (bs, 1H), 8.40 (d, J ) 8.8 Hz, 1H), 7.96 (d, J ) 8.4
Hz, 1H), 7.66 (d, J ) 2.8 Hz, 1H), 7.48 (dd, J ) 8.8, 2.4 Hz,
1H), 7.24 (d, J ) 8.0 Hz, 1H), 7.18-7.13 (m, 2H), 6.94-6.89

Bioisosteres and Congeners of the Agent XK469
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 14 3135
(m, 2H), 4.82 (q, J ) 6.4 Hz, 1H), 1.51 (d, J ) 7.2 Hz, 3H). 13
C
2-{4-[(7-Met h yl-2-q u in olin yl)oxy]p h en oxy}p r op ion ic
Acid (21f). To quinoline 19f (0.34 g, 1.9 mmol), 20 (0.35 g,
1.9 mmol), and DMF (10 mL) was added, in portions, 60% NaH
(0.23 g, 5.8 mmol), and the mixture was refluxed for 2 h. Pure
material (0.20 g, 32% yield) was obtained, after crystallization
from AcOEt-heptane, as light yellow crystals; mp 183-185
NMR (75 MHz, DMSO-d6): δ 173.6, 162.8, 155.0, 147.1, 146.6,
140.6, 135.0, 129.9, 126.1, 125.6, 124.3, 123.0, 116.0, 113.5,
72.4, 18.7. IR (KBr): 3440 (OH), 1705 (CdO) cm-1. MS (EI):
m/z (%) 343 (M+, 46), 298 (15), 284 (16), 270 (71), 254 (8), 236
(6), 167 (19), 162 (100), 155 (8), 127 (22), 114 (10), 97 (11), 91
(24), 83 (16), 81 (12), 73 (19), 71 (14), 69 (23), 67 (12), 63 (12),
60 (17), 57 (27), 55 (35), 45 (18). HRMS (EI): m/z 343.0609
(M+, calcd for C18H14NClO4, 343.0611). Anal. (C18H14NClO4)
C, H, N. (R)-(+) enantiomer: mp 160-161 °C; [R]D ) +19.5°
(c ) 0.50, 0.1 N NaOH). Chiral HPLC separation ((S) enan-
tiomer, 5.8 min, (R) enantiomer, 8.1 min) using Astec Chiro-
biotic T 250 mm × 4.6 mm, 65% H2O, 35% CH3OH, 20 mM
NH4NO3 at 1 mL/min with detection at 250 nm.
1
°C. H NMR (400 MHz, DMSO-d6): δ 13.03 (bs, 1H), 8.29 (d,
J ) 8.8 Hz, 1H), 7.78 (d, J ) 8.0 Hz, 1H), 7.43 (s, 1H), 7.28 (d,
J ) 8.4 Hz, 1H), 7.16-7.10 (m, 3H), 6.93-6.89 (m, 2H), 4.82
(q, J ) 6.4 Hz, 1H), 2.41 (s, 3H), 1.51 (d, J ) 6.4 Hz, 3H). 13C
NMR (100 MHz, DMSO-d6): δ 173.9, 162.4, 155.1, 147.6, 146.6,
140.6 (2C), 128.0, 127.4, 127.0, 124.0, 123.4, 116.1, 112.3, 72.5,
21.9, 19.1. IR (KBr): 3460 (OH), 1725 (CdO) cm-1. MS (EI):
m/z (%) 323 (M+, 57), 305 (6), 278 (9), 276 (7), 264 (13), 250
(60), 236 (10), 234 (6), 222 (5), 142 (100), 115 (17), 105 (6), 77
(6). HRMS (EI): m/z 323.1164 (M+, calcd for C19H17NO4,
323.1158). Anal. (C19H17NO4) C, H, N.
2-{4-[(6-Ch lor o-2-q u in olin yl)oxy]p h en oxy}p r op ion ic
Acid (21c). Quinoline 19c (0.20 g, 1.0 mmol), 20 (0.18 g, 1.0
mmol), anhydrous K2CO3 (0.35 g, 2.5 mmol), and DMF (5 mL)
were refluxed overnight. Pure material (0.15 g, 44% yield) was
obtained after crystallization from AcOEt-heptane as white
crystals; mp 173-174 °C. 1H NMR (300 MHz, DMSO-d6): δ
13.03 (bs, 1H), 8.32 (d, J ) 9.0 Hz, 1H), 8.02 (s, 1H), 7.60 (s,
2H), 7.25 (d, J ) 8.7 Hz, 1H), 7.14 (d, J ) 8.4 Hz, 2H), 6.90 (d,
J ) 8.4 Hz, 2H), 4.80 (q, J ) 6.6 Hz, 1H), 1.50 (d, J ) 6.6 Hz,
3H). 13C NMR (75 MHz, DMSO-d6): δ 173.5, 162.4, 155.0,
147.2, 144.6, 140.0, 130.6, 129.4, 126.9, 126.6, 123.0, 116.0,
114.3, 72.4, 18.8. IR (KBr): 3425 (OH), 1735 (CdO) cm-1. MS
(EI): m/z (%) 343 (M+, 8), 270 (9), 208 (27), 182 (54), 180 (6),
169 (26), 162 (21), 149 (7), 137 (6), 125 (10), 111 (19), 109 (14),
104 (15), 97 (42), 95 (33), 91 (18), 83 (58), 77 (32), 69 (91), 67
(57), 65 (12), 57 (64), 55 (100), 51 (16). HRMS (EI): m/z
2-{4-[(7-Me t h o x y -2-q u in o lin y l)o x y ]p h e n o x y }p r o -
p ion ic Acid (21g). Quinoline 19g (0.39 g, 2.0 mmol), 20 (0.36
g, 2.0 mmol), anhydrous K2CO3 (0.69 g, 5.0 mmol), and DMF
(10 mL) were refluxed overnight. Pure material (0.45 g, 66%
yield) was obtained after crystallization from AcOEt-heptane
1
as light yellow crystals; mp 164-166 °C. H NMR (400 MHz,
DMSO-d6): δ 13.06 (bs, 1H), 8.25 (d, J ) 8.8 Hz, 1H), 7.78 (d,
J ) 8.8 Hz, 1H), 7.16-7.10 (m, 2H), 7.06 (dd, J ) 8.8, 2.4 Hz,
1H), 7.02 (d, J ) 8.0 Hz, 1H), 6.99 (d, J ) 2.4 Hz, 1H), 6.94-
6.88 (m, 2H), 4.82 (q, J ) 6.4 Hz, 1H), 3.81 (s, 3H), 1.51 (d, J
) 7.2 Hz, 3H). 13C NMR (100 MHz, DMSO-d6): δ 174.0, 162.9,
161.5, 155.1, 148.3, 147.7, 140.5, 129.5, 123.4, 120.9, 117.5,
116.1, 110.5, 107.0, 72.5, 56.1, 19.1. IR (KBr): 3415 (OH), 1735
(CdO) cm-1. MS (EI): m/z (%) 339 (M+, 62), 323 (10), 294 (8),
280 (13), 266 (35), 250 (13), 175 (7), 158 (100), 142 (18), 115
343.0608 (M+, calcd for C18H14NClO4, 343.0611). Anal. (C18H14
NClO4) C, H, N.
-
(10), 77 (6). HRMS (EI): m/z 339.1105 (M+, calcd for C19H17
-
2-{4-[(7-Br om o-2-q u in olin yl)oxy]p h en oxy}p r op ion ic
Acid (21d ). Quinoline 19d (0.79 g, 3.3 mmol), 20 (0.61 g, 3.3
mmol), anhydrous K2CO3 (1.13 g, 8.18 mmol), and DMF (20
mL) were refluxed overnight. Pure material (1.03 g, 82% yield)
was obtained after crystallization from AcOEt-heptane as
NO5, 339.1107). Anal. (C19H17NO5) C, H, N.
2-{4-[(5-C h lo r o -2-b e n zo x a zo ly l)o x y ]p h e n o x y }p r o -
p ion ic Acid (23a ). The methyl ester of 23a was prepared by
refluxing for 4 h a mixture of 22a (0.47 g, 2.5 mmol), 3 (0.49
g, 2.5 mmol), anhydrous K2CO3 (0.41 g, 3.0 mmol), and CH3-
CN (15 mL). Pure material (0.76 g, 87% yield), in the form of
a light yellow oil, was obtained after chromatography (4:1
1
white crystals; mp 160-161 °C. H NMR (400 MHz, DMSO-
d6): δ 13.09 (bs, 1H), 8.39 (d, J ) 8.8 Hz, 1H), 7.88 (d, J ) 9.2
Hz, 1H), 7.80 (d, J ) 1.6 Hz, 1H), 7.60 (dd, J ) 9.2, 1.6 Hz,
1H), 7.25 (d, J ) 8.8 Hz, 1H), 7.18-7.13 (m, 2H), 6.94-6.89
1
hexanes:AcOEt). H NMR (400 MHz, CDCl3): δ 7.46 (d, J )
(m, 2H), 4.82 (q, J ) 6.8 Hz, 1H), 1.51 (d, J ) 7.2 Hz, 3H). 13
C
1.6 Hz, 1H), 7.31 (d, J ) 8.8 Hz, 1H), 7.32-7.28 (m, 2H), 7.19
(dd, J ) 8.4, 2.0 Hz, 1H), 6.97-6.91 (m, 2H), 4.75 (q, J ) 6.8
Hz, 1H), 3.77 (s, 3H), 1.63 (d, J ) 6.4 Hz, 3H). 13C NMR (400
MHz, CDCl3): δ 172.6, 163.5, 156.0, 147.2, 147.0, 142.1, 130.2,
123.8, 121.5, 119.1, 116.5, 110.8, 73.4, 52.7, 18.8. IR (film):
1750 (CdO) cm-1. MS (EI): m/z (%) 347 (M+, 100), 312 (2),
288 (84), 261 (34), 244 (6), 233 (4), 216 (6), 205 (5), 188 (15),
182 (18), 170 (11), 162 (9), 153 (13), 140 (16), 119 (23), 91 (24),
76 (41), 63 (33), 59 (50), 55 (19), 50 (21), 43 (14), 39 (15). HRMS
(EI): m/z 347.0563 (M+, calcd for C17H14NClO5, 347.0561).
NMR (75 MHz, DMSO-d6): δ 173.9, 163.0, 155.3, 147.2, 147.1,
141.0, 130.3, 129.6, 128.5, 124.9, 124.0, 123.3, 116.1, 114.0,
72.5, 19.1. IR (KBr): 3415 (OH), 1705 (CdO) cm-1. MS (EI):
m/z (%) 387 (M+, 42), 342 (10), 328 (10), 314 (31), 300 (6), 285
(7), 256 (22), 236 (13), 206 (53), 199 (18), 185 (10), 171 (8), 157
(8), 127 (44), 115 (15), 111 (13), 97 (27), 91 (28), 83 (33), 73
(57), 69 (45), 60 (58), 57 (56), 55 (69), 43 (100), 41 (66). HRMS
(EI): m/z 387.0107 (M+, calcd for C18H14NBrO4, 387.0106).
Anal. (C18H14NBrO4) C, H, N. (R)-(+) enantiomer: mp 166-
167 °C; [R]D ) +22.0° (c ) 0.50, 0.1 N NaOH). Chiral HPLC
separation ((S) enantiomer, 5.9 min; (R) enantiomer, 8.5 min)
using Astec Chirobiotic T 250 mm × 4.6 mm, 65% H2O, 35%
CH3OH, 20 mM NH4NO3 at 1 mL/min with detection at 250
nm.
Saponification of the methyl ester of 23a (0.61 g, 1.8 mmol)
was effected with 0.1 N K2CO3 (35 mL, 3.5 mmol) in THF (40
mL). The mixture was extracted with AcOEt, followed by
filtration of the dried (MgSO4) extract through silica gel and
evaporation of the clear solution to dryness. Crystallization
of the residue from AcOEt-hexanes gave 23a (0.21 g, 36%
yield) as an off-white solid; mp 167-168 °C. 1H NMR (400
MHz, DMSO-d6): δ 7.65 (d, J ) 8.8 Hz, 1H), 7.61 (d, J ) 2.4
Hz, 1H), 7.43-7.38 (m, 2H), 7.30 (dd, J ) 8.4, 2.0 Hz, 1H),
6.99-6.93 (m, 2H), 4.87 (q, J ) 6.8 Hz, 1H), 1.51 (d, J ) 6.8
Hz, 3H). 13C NMR (400 MHz, DMSO-d6): δ 173.7, 163.8, 156.4,
147.4, 146.8, 142.4, 129.5, 124.0, 122.3, 116.4, 112.1, 72.6, 18.9.
IR (KBr): 2880 (OH), 1725 (CdO) cm-1. MS (EI): m/z (%) 333
(M+, 100), 304 (4), 288 (40), 274 (77), 261 (92), 248 (23), 232
(12), 220 (30), 216 (16), 205 (10), 188 (48), 182 (42), 168 (33),
162 (23), 153 (35), 144 (12), 140 (41), 124 (15), 119 (24), 109
(25), 92 (45), 81 (26), 76 (88), 63 (90), 55 (32), 50 (47), 45 (56),
39 (45). HRMS (EI): m/z 333.0401 (M+, calcd for C16H12NClO5,
333.0404). Anal. (C16H12NClO5) C, H, N.
2-{4-[(7-Iodo-2-qu in olin yl)oxy]ph en oxy}pr opion ic Acid
(21e). Quinoline 19e (0.29 g, 1.0 mmol), 20 (0.18 g, 1.0 mmol),
anhydrous K2CO3 (0.35 g, 2.5 mmol), and DMF (5 mL) were
refluxed overnight. Pure material (0.34 g, 78% yield) was
obtained after crystallization from AcOEt as white crystals;
1
mp 138-140 °C. H NMR (400 MHz, DMSO-d6): δ 13.04 (bs,
1H), 8.34 (d, J ) 9.2 Hz, 1H), 7.99 (s, 1H), 7.73 (dd, J ) 8.4,
1.6 Hz, 1H), 7.68 (d, J ) 8.8 Hz, 1H), 7.23 (d, J ) 8.8 Hz, 1H),
7.18-7.12 (m, 2H), 6.95-6.89 (m, 2H), 4.82 (q, J ) 6.4 Hz,
1H), 1.52 (d, J ) 6.4 Hz, 3H). 13C NMR (100 MHz, DMSO-d6):
δ 173.9, 162.7, 155.2, 147.3, 147.2, 141.0, 136.0, 133.8, 130.0,
125.1, 123.3, 116.2, 114.1, 97.5, 72.6, 19.1. IR (KBr): 3440
(OH), 1735 (CdO) cm-1. MS (EI): m/z (%) 435 (M+, 100), 390
(14), 376 (20), 362 (49), 346 (4), 309 (10), 284 (41), 271 (53),
254 (84), 236 (23), 219 (6), 207 (6), 181 (5), 144 (5), 127 (44),
116 (14), 100 (7), 89 (7), 43 (6). HRMS (EI): m/z 434.9961
(M+, calcd for C18H14NIO4, 434.9966). Anal. (C18H14NIO4) C,
H, N.
Biologic Testin g Meth od s: In Vitr o.1a A brief description
of the methods follows. All materials were initially tested in a
disk diffusion soft agar colony formation assay (disk assay).
The disk assay is designed to compare the relative cytotoxicity

3136 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 14
Hazeldine et al.
of an agent against leukemia cells, solid tumor cells (including
multidrug resistant solid tumors), and normal cells. The
inhibition is expressed in zone units, with 200 units ) 6.5 mm.
On average, a 10-fold dilution of a cytotoxic agent produces a
posttreatment (Rx) approximates the Td values of the tumors
in untreated control mice.
duration of treatment of solid tumor, 5-20 days
330 zone unit change. Activity against
a drug sensitive
antitumor activity
highly active
gross log tumor cell kill
leukemia (L1210 or P388) provides the reference point. The
leukemic cell can represent antiproliferative leukemic active
agents of past discoveries. The agent needs greater activity
against the drug insensitive solid tumors than against the
leukemia cells. Normal fibroblasts were used in current
studies. For the operation of the assay, the tumor cells are
isolated from live tissue, i.e., a tumor growing in a mouse. The
cells are then seeded in the soft agar. The drug is placed on a
filter paper disk (standard hole punch of Whatman no. 1),
which is then placed on top of the soft agar (60 mm plate).
The drug diffuses off the disk as the tumor cells are replicating,
creating a zone of inhibition of colony formation. Those
materials with sufficient cytotoxicity (>400 units) and tumor
selectivity progressed to in vivo evaluation in tumor-bearing
mice as described below.
++++
+++
++
>2.8
2.0-2.8
1.3-1.9
0.7-1.2
<0.7
+
inactive
-
3. Regr ession s for Ad va n ced Sta ged Tu m or s. (i) Partial
regression: regression of the tumor to less than 50% of the
pretreatment size; (ii) complete regression: regression of the
tumor to below limit of palpation (<50 mg); and (iii) cures:
there were no cures in the experiments reported.
4. Non qu a n tita tive Deter m in a tion of An titu m or Ac-
tivity by Tu m or Gr ow th In h ibition (T/C Va lu e). The
treatment and control groups are measured when the control
group tumors reach approximately 700-1200 mg in size
(median of group). The median tumor weight of each group is
determined, including zeros. The T/C value in percent is an
indication of antitumor effectiveness. A T/C equal to or less
than 42% is considered significant antitumor activity by the
Drug Evaluation Branch of the Division of Cancer Treatment
(NCI). A T/C value <10% is considered to indicate highly
significant antitumor activity and is the level used by NCI to
justify a clinical trial if toxicity, formulation, and certain other
requirements are met (termed DN-2 level activity). A body
weight loss nadir (mean of group) of greater than 20% or
greater than 20% drug deaths is considered to indicate an
excessively toxic dosage in a single course trial.
In Vivo. Treatment was carried out against advanced/early
stage pancreatic ductal adenocarcinoma-03 and/or early mam-
mary adenocarcinoma-17/Adr. All are sensitive to 1. The Mam-
17/Adr is
tumor.
a p-glycoprotein positive multidrug resistant
a . Tu m or a n d An im a l Ma in ten a n ce. Mouse tumors were
maintained in the mouse strain of origin and were trans-
planted into the appropriate F1 hybrid (or the inbred mouse
of origin) for therapy trials. Individual mouse body weights
for each experiment were within 5 g, and all mice were over
17 g at the start of therapy. The mice were supplied food and
water ad libitum.
b. Ch em oth er a p y of Solid Tu m or s. The animals were
pooled, implanted subcutaneously with 30-60 mg tumor
fragments by a 12 gauge trocar, and again pooled before
unselective distribution to the various treatment and control
groups (five or six mice per group). For early stage treatment,
chemotherapy was started 1-3 days after tumor implantation
while the number of cells is relatively small (107 to 5 × 107
cells). For advanced stage tumors, treatment was delayed until
the tumors were in the 150-350 mg size (1.5 × 108 to 3.5 ×
108 cells). Tumors were measured with a caliper twice weekly
or three times weekly for the more rapidly growing tumors.
Mice were sacrificed when their tumors reached 1500 mg (i.e.,
before they could cause the animal discomfort). Tumor weights
were estimated from two-dimensional measurements. Dose
schedules were adjusted for toxicity; accordingly, doses re-
ported in Table 1 are not the same, because of the toxicity
encountered at the top dose(s), at which time treatment was
terminated for all doses. Therefore, the highest achieved dose
is reported.
Ack n ow led gm en t. We are grateful for the support
of this research through grants from the National
Institutes of Health (CA82341), the Virtual Discovery
Program of the Barbara Ann Karmanos Institute, and
the J ack and Miriam Schenkman Research Fund.
Thanks are due to the Resource Laboratory of the
Chemistry Department, Wayne State University, De-
troit, MI, wherein instrumental analyses were per-
formed.
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
cedures for the series 4a -d , 12a -c, 13a -c, 14a ,b, 15a ,b,
16a ,b, 17a ,b, 18a ,b, 23c,d , 25a ,b, and 27 not tested in vivo
and chiral HPLC separation of 21b. This material is available
free of charge via the Internet at http://pubs.acs.org/.
c. Tu m or Weigh t. The tumor weight (in mg) ) (a × b2)/2,
where a and b are the tumor length and width in (mm),
respectively.
Refer en ces
(1) (a) Hazeldine, S. T.; Polin, L.; Kushner, J .; Paluch, J .; White,
K.; Edelstein, M.; Palomino, E.; Corbett, T. H.; Horwitz, J . P.
Design, Synthesis and Biological Evaluation of Analogues of the
Antitumor Agent 2-{4-[(7-Chloro-2-quinoxalinyl)oxy]phenoxy}-
propionic acid (XK469). J . Med. Chem. 2001, 44, 1758-1776.
(b) Wermuth, C.-G.; Ganellin, C. R.; Lindberg, P.; Mitscher, L.
A. Glossary of terms used in Medicinal Chemistry (IUAPAC
recommendations 1997). Annu. Rep. Med. Chem. 1998, 33, 385-
395.
(2) Serban, A.; J ensen, W. A. Substituted Phenylamine and Phen-
yloxy-Quinazolines as Herbicides. U.S. Patent 4,675,047, 1987.
(3) Klauke, E.; Oehlmann, L. Herstellung von 2-(Mono-D- und
Trichloromethyl)phenyl-Isocyanates. Synth. Commun. 1978, 8,
377-378.
(4) Sasse, K. Ein einfaches neues Verfahren zur Herstellung 2-sub-
stituierter Chinazoline. Synth. Commun. 1978, 8, 379-382.
(5) (a) Wolf, F. J .; Pfister, K., III. Benzotriazines. U.S. Patent 2,-
489,353, 1949. (b) Wolf, F. J .; Pfister, K, III. Benzotriazines. U.S.
Patent 2,489,354, 1949.
(6) Luckenbaugh, R. W. Benzotriazines Derivatives as Selective
Weed Control Agents. U.S. Patent 4,368,068, 1983.
(7) Yasukazu, U.; Sakata, G.; Kenzi, M.; Yasuo, K. Heterocyclic
Ether Type Phenoxy Fatty Acid Derivatives and Herbicidal
Composition. U.S. Patent 4,629,493, 1986.
d . Qu a n tified En d P oin ts for Assessin g An titu m or
Activity for Solid Tu m or s. The following quantified end
points are used to assess antitumor activity.
1. Tu m or Gr ow th Dela y (T-C Va lu e). T is the median
time (in days) required for the treatment group tumors to reach
a predetermined size (e.g., 1000 mg), and C is the median time
(in days) for the control group tumors to reach the same size.
Tumor-free survivors are excluded from these calculations
(cures are tabulated separately). In our judgment, this value
is the single most important criterion of antitumor effective-
ness because it allows the quantification of tumor cell kill.
2. Ca lcu la tion of Tu m or Cell Kill. For subcutaneously
(SC) growing tumors, the log cell kill is calculated from the
following formula: log cell kill total (gross) ) T-C value in
days (3.32) (Td), where T-C is the tumor growth delay as
described above and Td is the tumor volume doubling time in
days, estimated from the best fit straight line from a log-linear
growth plot of the control group tumors in exponential growth
(100-800 mg range). The conversion of the T-C values to log
cell kill is possible because the Td of tumors regrowing
(8) Effenberger, F.; Hartmann, W. Synthesen Mit â-A¨ thoxy-a¨cryl-
saurechloriden. Chem. Ber. 1969, 102, 3260-3257.

Bioisosteres and Congeners of the Agent XK469
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 14 3137
(9) (a) Campbell, S. F.; Roberts, D. Quinoline Ionotropic Agents. U.S.
Patent 4,710,507, 1987. (b) Alabaster, C.; Bell, A. S.; Campbell,
S. F.; Ellis, P. Henderson, C. G.; Roberts, D. A.; Samuels, G. M.
R.; Stefaniak, M. H. 1(1H)-Quinolones with Cardiac Stimulant
Activity. 1. Synthesis and Biological Activities of (Six-Membered
Heteroaryl)-Substituted Derivatives. J . Med. Chem, 1988, 31,
2048-2056.
(14) Scherter, R.; Rempfler, H. Methyl R-[4-(6′-methyl-5′-carbothi-
amido-pyrid-2-yl)oxy-phenoxy]propionate. U.S. Patent 4,253,866,
1981.
(15) Shin, K. H.; Lim, S. S.; J ung, S. H.; J i, J .; Lee, E. B.; Kim, D. C.;
Shin, K. J .; Kim, D. J .; Park, S. W. Synthesis and Antiinflam-
matory and Analgesic Activities of Pyridyloxy- and Phenoxy-
alkanoic Acid Derivatives. Arch. Pharm. Res. 2000, 23, 17-21.
(16) Polin, L.; White, K.; Kushner, J .; Paluch, J .; Simpson, C.; Pugh,
S.; Edelstein, M. K.; Hazeldine, S.; Fontana, J .; LoRusso, P.;
Horwitz, J . P.; Corbett, T. H. Preclinical Efficacy Evaluations
of XK-469: Dose Schedule, Route and Cross-Resistance Behavior
in Tumor Bearing Mice. Invest. New Drugs 2002, 20, 13-22.
(17) Personal communication: Dr. Ralph E. Parchment, Karmanos
Cancer Institute, Detroit, MI.
(10) Handt, R.; Hu¨rlein, G.; Ko¨cher, H.; Langelu¨ddike, P. Heterocyclic
Phenyl Ethers. U.S. Patent 4,130,413, 1978.
(11) Becherer J .; Handt, R.; Nestler, H. J .; Kussmaul, U. Process for
the Preparation of 2-Chloro-benzoxazoles. U.S. Patent 4,714,-
766, 1987.
(12) Serban, A.; Watson, K. G.; Barton, J . E. D. Phenylamine
Substituted on Amine with a Benzo(Oxa, Thia, or Di)Azole
Group. U.S. Patent 4,314,065, 1982.
(13) Takahashi, R.; Fujikawa, K.; Yokomichi, I.; Tsuji, Y.; Sakashita,
N. Herbicidal Compound, Herbicidal Composition Containing the
Same and Method of Use Thereof. U.S. Patent 4,046,553, 1977.
J M0200097