Synthesis of novel quinolone and quinoline-2-carboxylic acid (4-morpholin-4-yl-phenyl)amides: A late-stage diversification approach to potent 5HT1B antagonists

Article abstract of DOI:10.1016/j.bmc.2006.10.037

Multiparallel amenable syntheses of 6-methoxy-8-amino-4-oxo-1,4-dihydroquinoline-2-carboxylic acid-(4-morpholin-4-yl-phenyl)amides (I) and 4-amino-6-methoxy-8-(4-methyl-piperazin-1-yl)-quinoline-2-carboxylic acid (4-morpholin-4-yl-phenyl)amides (II) which facilitate late-stage diversification at the 8-position of (I) and at the 4- and 8-positions of (II) are described. The resulting novel series were determined to contain potent 5HT_1B antagonists. Preliminary SAR data are presented.

Full text of DOI:10.1016/j.bmc.2006.10.037

Bioorganic & Medicinal Chemistry 15 (2007) 939–950
Synthesis of novel quinolone and quinoline-2-carboxylic acid
(4-morpholin-4-yl-phenyl)amides: A late-stage diversification
approach to potent 5HT1B antagonists
Carey L. Horchler,* John P. McCauley, Jr., James E. Hall, Dean H. Snyder,
W. Craig Moore, Thomas J. Hudzik and Marc J. Chapdelaine
CNS Chemistry and Neuroscience, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USA
Received 2 June 2006; revised 5 October 2006; accepted 18 October 2006
Available online 20 October 2006
Abstract—Multiparallel amenable syntheses of 6-methoxy-8-amino-4-oxo-1,4-dihydroquinoline-2-carboxylic acid-(4-morpholin-4-
yl-phenyl)amides (I) and 4-amino-6-methoxy-8-(4-methyl-piperazin-1-yl)-quinoline-2-carboxylic acid (4-morpholin-4-yl-phen-
yl)amides (II) which facilitate late-stage diversification at the 8-position of (I) and at the 4- and 8-positions of (II) are described.
The resulting novel series were determined to contain potent 5HT1B antagonists. Preliminary SAR data are presented.
Published by Elsevier Ltd.
1. Introduction
antidepressant activity than currently available thera-
pies.2,4 Recent studies on 5HT1B selective antagonists
are beginning to substantiate this hypothesis.5 Two
5HT1B antagonists have been shown to be active in ani-
mal models for anxiolytic and antidepressant effects.6
The 5-hydroxytryptamine1 (5HT1) receptor family con-
sists of five receptor subtypes (5HT1A, 5HT1B, 5HT1D
,
5HT1E, and 5HT1F) all of which are G-protein coupled,
seven transmembrane receptors.1 It is thought that there
are potentially four distinct signal transduction mecha-
nisms for these receptors. They both activate and inhibit
adenylate cyclase, modulate potassium channel activity
in the hippocampus, and activate phosphoinositide
(PI) metabolism.1b The 5HT1A receptor has been studied
extensively for its potential in the treatment of depres-
sion, anxiety, and psychosis.1a,2 The 5HT1B,D,F recep-
tors have been primarily indicated in the treatment of
migraine.1a However, the 5HT1B receptor has recently
been targeted for its potential in the treatment of depres-
sion, anxiety, and other serotoninergic neurotransmis-
sion related psychiatric disorders.2b,3 The release of
5-HT is regulated by autoreceptors on the 5-HT nerve
terminals. It has been suggested that antagonists of the
terminal 5HT1 autoreceptors (5HT1B/1D) which block
terminal 5HT1B receptors may effect immediate 5-HT
release, thereby increasing 5-HT transmission at the
synapses and ultimately providing faster clinical
In a continuation of our efforts to discover an orally ac-
tive 5HT1B antagonist for the treatment of anxiety and
depression, we sought to improve on AR-A000002, a
selective 5HT1B antagonist (Fig. 1) which has been
shown to have potential as both an antidepressive and
an anxiolytic agent.6a,7 Pharmacophore model scoring
opposite AR-A000002 and other known 5HT1B antago-
nists led to the identification of the quinolone and
quinoline cores as potential replacements to the
2-aminotetralin core (Fig. 2).
We wished then to evaluate the novel quinoline series as
a new class of 5HT1B antagonists. This necessitated
O
N
H
N
N
O
AR-A000002
N
Keywords: 5HT1B antagonist; 8-Amino-4-oxo-1,4-dihydroquinoline-2-
carboxylic acid amides; 4-Aminoquinoline-2-carboxylic acid amide.
*
Figure 1. The legacy compound, AR-A000002, served as a starting
point for the quinoline series.
Corresponding author. Tel.: +1 302 886 7439; fax: +1 302 886 5382;
e-mail: carey.horchler@astrazeneca.com
0968-0896/$ - see front matter Published by Elsevier Ltd.
doi:10.1016/j.bmc.2006.10.037

940
C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
Y
A provided the 8-bromo-6-methoxy-4-oxo-1,4-dihydro-
quinoline-2-carboxylic acid methyl ester (2) in much
better yield than the corresponding cyclization in
polyphosphoric acid.9 The methyl ester was hydrolyzed
to the acid (3) using lithium hydroxide. The required 8-
bromo-6-methoxy-4-oxo-1,4-dihydroquinoline-2-car-
boxylic acid (4-morpholin-4-yl-phenyl)amide (4) was
prepared through standard coupling of 3 and 4-mor-
pholinoaniline. The Buchwald–Hartwig reaction10 was
envisaged as the means of rapidly introducing a variety
of 8-amino groups into I and II. Attempts to obtain 7
from the unprotected quinolone 4 using tris(dibenzylide-
neacetone)dipalladium(0) (Pd2(dba)3), 2,2-bis(diphe-
nylphospino)-1,10-binaphthalene (BINAP), and cesium
carbonate (Cs2CO3) or potassium fluoride (KF) failed
to elucidate a means of direct conversion. It was conjec-
tured that under the strongly basic reaction conditions,
the increased electron density of the deprotonated
quinolone ring11 was preventing the desired reaction
from occurring. Protection of the 4-oxo group of 4
was accomplished by introduction of a 2-trimethylsila-
nylethoxymethoxy (SEM) group under standard
conditions to afford 8-bromo-6-methoxy-4-(2-trimeth-
ylsilanylethoxymethoxy) quinoline-2-carboxylic acid
(4-morpholin-4-yl-phenyl)amide (5). Complete regiose-
lectivity was confirmed by 2D HMBC NMR experi-
ments. Intermediate 5 was then sucessfully employed
in the coupling reaction to introduce a variety of amines
in generally excellent yields (Table 1). The desired 6-
methoxy-8-amino-4-oxo-1,4-dihydro-quinoline-2-car-
boxylic acid (4-morpholin-4-yl-phenyl)amides 7a–h
were then obtained by the removal of the SEM group
in the presence of HCl.
O
4
X
4
X
6
H
6
8
N
H
8
N
N
N
H
N
O
R1
R2
N
N
O
N
R1
R2
O
O
II
I
X=OMe, F Y=NR'R'', OMe
Figure 2. The quinolone and quinoline cores were targeted as stable
potential 5HT1B antagonists.
syntheses which would allow late-stage diversification of
the 4-oxo-1,4-dihydroquinolines (I) at the 8-position
and of the quinolines (II) at the 4- and 8-positions.
The chemistry developed for these series allowed for
exploration of portions of the molecule which were more
difficult to explore in the 2-aminotetralin core. Within,
we describe multiparallel amenable syntheses (MPS)
which allowed for the expedient evaluation of several
quinoline derivatives as 5HT1B antagonists.
2. Discussion
The synthesis of the 4-oxo-1,4-dihydroquinolines was
initiated by addition of dimethyl acetylenedicarboxylate
to a solution of 2-bromo-4-methoxy aniline8 in anhy-
drous methanol, followed by heating at reflux to afford
2-(2-bromo-4-methoxy-phenylamino)-but-2-enedioic
acid dimethyl ester (1). The key quinolone intermediate
2 (Scheme 1) was obtained by adaptation of the proce-
dure of Heindel et al.9 Cyclization of 1 in DowThermꢀ
O
O
O
R
CO2Me
CO2Me
CO2Me
CO2Me
O
O
R
R
c
d
a
b
+
H
N
N
H
CO2H
N
H
N
H
CO2Me
Br
N
H
Br
Br
e
O
Br
NH2
Br
N
1, R=OMe
8, R=F
2, R=OMe
9, R=F
3
4
R= OMe, F
O
e
SiMe3
SiMe3
SiMe3
O
O
SiMe3
O
N
O
N
O
O
O
O
R
R
O
R
H
f
f
OMe
N
H
N
N
N
CO2Me
O
N
O
N
N
Br
O
Br
R1
R2
R1
R2
N
5
O
6a-h, R=OMe
10, R=F
13, R=OMe
11, R=F
14, R=OMe
O
c
g
O
O
R
R
H
d
N
OH
N
N
H
O
H
O
N
N
N
R1
R2
R1
R2
O
7a-h, R=OMe
7i, R=F
12, R=F
15, R=OMe
Scheme 1. Synthesis of 4-oxo-1,4-dihydroquinolines 7a–i. Reagents and conditions: (a) MeOH, reflux, 8 h, 82–93%; (b) DowThermꢀ A, 240–245 ꢁC,
45 min, 78%; (c) 3 equiv LiOHÆH2O, 3:1:1 THF/MeOH/H2O, RT, 5 h, 95–100%; (d) 2.4 equiv TBTU, 2.4 equiv HOBt, 1.3 equiv 4-morpholinoan-
iline, 4.3 equiv DIEA, DMF, RT, 16 h, 43–58%; (e) 1.5 equiv NaH, 1.3 equiv SEMCl, NMP, RT, 4.5 h, 78–100%; (f) 1.6 equiv appropriate amine,
˚
5 mol % Pd2(dba)3, 0.3 equiv BINAP, 4 equiv Cs2CO3, 4 A molecular sieves, toluene, reflux, 17 h, 75–92%; (g) 0.05 N aq HCl, MeOH, RT, 45 min,
13–80% (yield from 5).

C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
Table 1. Structure–activity relationships of quinolones 7a–i
941
Cl
O
O
H
a,b
X
c
N
3
N
H
N
Br
O
N
H
16
N
O
z
O
N
7a-i
O
Y
N
Y
O
O
Compound
X
Z
Kia (nM)
Yieldb
81
%
d
H
H
N
N
N
N
N
N
7a
OMe
OMe
OMe
OMe
OMe
OMe
OMe
0.9 (n = 3)
N
O
Br
O
N
N
O
17a-b
18a-b
O
N
N
7b
7c
7d
7e
7f
292
3.5
392
35
79
85c
78
a: Y= N(CH3)2
b: Y= NHCH3
N
N
N
N
N
Scheme 2. Diversification at the 4- and 8-positions of the quinolines
18. Reagents and conditions: (a) 9.8 equiv oxalyl chloride, cat. DMF,
CH2Cl2, reflux, 2 h, reaction concentrated; (b) 1.1 equiv 4-morpho-
lino aniline, 3.5 equiv DIEA, CH2Cl2, RT, 1 h, 49% (from 3); (c)
2.0 M appropriate amine in THF, 100 ꢁC, 60–80 psi, 18 h, 87–92%;
N
(d) 1.5 equiv N-methylpiperizine, 6 mol
% Pd2(dba)3, 0.3 equiv
˚
BINAP, 4.7 equiv Cs2CO3, 4 A molecular sieves, toluene, reflux,
20 h, 57–67%.
100
N
N
The synthesis of the desired quinolines 18a and 18b also
employed carboxylic acid 3 (Scheme 2). Diversification
at both the 4- and 8-positions was achieved by treatment
of 3 with oxalyl chloride in methylene chloride and
catalytic DMF, followed by isolation of the 4-chloro
quinoline acid chloride. Subsequent addition of 4-mor-
pholinoaniline and diisopropylethylamine provided
8-bromo-4-chloro-6-methoxyquinoline-2-carboxylic acid
(4-morpholin-4-yl-phenyl)amide (16). Intermediate 16
could then be diversified by sequential displacement of
the 4-chloro group under thermal conditions, followed
by catalytic coupling of amino moities at the 8-bromo
position. Our initial evaluation required displacement
of the chloro group with N,N-dimethyl amine and
N-methyl amine. The 8-bromo-substituted amino-
quinolines 17 proved competent substrates for the
Buchwald–Hartwig reaction affording the 4-amino-6-meth-
oxy-8-(4-methyl-piperazin-1-yl)-quinoline-2-carboxylic acid
(4-morpholin-4-yl- phenyl)amides 18a and 18b in
acceptable yields (Table 2).
>1000 (n = 2) 100
7g
170
100
50
N
N
N
7h
7i
OMe
F
>1000
9.3
N
88d
N
N
a 5HT1B binding affinity was determined as described in Refs. 5d and
13. Geometric mean values reported for multiple experiments.
b Yield of Buchwald–Hartwig coupling reaction from 5.
c Yield from 13.
d Yield from 10.
The 6-fluoroquinolone 7i was prepared in a similar fash-
ion from 2-bromo-4-fluoroaniline. As shown in Scheme
1, the steps in the synthesis for this compound were rear-
ranged such that 8-bromo-6-fluoro-4-oxo-1,4-dihydro-
quinoline-2-carboxylic acid methyl ester
9
was
Table 2. Structure–activity relationships of quinolines 18a–c
protected as the SEM derivative 10 and then subjected
to the Buchwald–Hartwig coupling reaction to give
6-fluoro-8-(4-methyl-piperazin-1-yl)-4-(2-trimethylsilan-
ylethoxymethoxy)-quinoline-2-carboxylic acid methyl
ester 11. The ester was hydrolyzed with concurrent loss
of the SEM group to give the quinolone carboxylic acid
12. Subsequent conversion to the amide provided the
desired 6-fluoro-8-(4-methyl-piperazin-1-yl)-4-oxo-1,4-
dihydro-quinoline-2-carboxylic acid (4-morpholin-4-yl-
phenyl)amide 7i. This alternative route was also
employed for the methoxy derivatives as exemplified in
the alternate synthesis of 7a which is included in Section
4. The route offers the advantage of potential late-stage
diversification at the amide position versus at the 8-ami-
no quinoline position should that be of interest.
Y
X
H
N
N
N
N
O
N
O
18a-c
Compound
X
Y
Kia (nM)
Yield %
18a
18b
18c
OMe
OMe
F
NMe2
NHMe
OMe
51
1300
30
67b
57b
90c
a 5HT1B binding affinity was determined as described in Refs. 5d and
13. Geometric mean values reported for multiple experiments.
b Yield of Buchwald–Hartwig coupling from 17.
c Yield of 18c from 19.

942
C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
The synthesis of 6-fluoro-4-methoxy-8-(4-methyl-pipera-
zin-1-yl)-quinoline-2-carboxylic acid (4-morpholin-4-yl-
phenyl)amide 18c was carried out in a similar manner
(Scheme 3). Sequential treatment of 8-bromo-6-fluoro-
4-oxo-1,4-dihydroquinoline-2-carboxylic acid methyl es-
ter (9) with sodium hydride and iodomethane afforded
8-bromo-6-fluoro-4-methoxyquinoline-2-carboxylic acid
methyl ester (19). Buchwald–Hartwig coupling condi-
tions were employed on the methoxy quinoline com-
pound to introduce the N-methyl piperazine group.
Hydrolysis of 20 and subsequent coupling of the acid
21 with 4-morpholinoaniline afforded the desired 6-fluo-
ro-4-methoxy-8-(4-methyl-piperazin-1-yl)-quinoline-2-
carboxylic acid (4-morpholin-4-yl-phenyl)amide 18c.
yl-3-amino-pyrrolidine derivative 7g exhibited modest
activity while the N,N0-dimethyl-3-amino-pyrrolidine
derivative 7h did not. This result made it apparent that
small changes such as an extra methylene group can
have a dramatic effect on activity.
The intrinsic affinity of 7a, 7c, and 7i was evaluated
using a GTPcS (a hydrolysis resistant analog of guano-
sine triphosphate) binding assay in order to confirm
antagonist properties. Agonist stimulated GTP binding
was measured in a stably transfected CHO cell line
expressing 5HT1B receptors using [35S]GTPcS as previ-
ously described.13,14 Maximal intrinsic affinity (IA)
was defined as the percent maximal 5-HT-induced stim-
ulation by 10 lM compound in the absence of 5-HT
with a negative number indicating full antagonism. All
three compounds were determined to be full antagonists.
(The intrinsic affinities ranged from ꢀ28 to ꢀ34.) Thus,
potent 5HT1B antagonists were obtained within the
4-oxo-1,4-dihydroquinoline series. The DMPK (disposi-
tion metabolism pharmacokinetic) properties of this
series, however, were somewhat disappointing. In par-
ticular, the compounds were found to have no oral
activity as determined in a guinea pig agonist induced
hypothermia model.13,15
Piperazine side chains commonly appear as elements of
5HT1B antagonists.12,5c,3a However, the available struc-
ture activity relationship (SAR) information surround-
ing this substituent is actually rather limited. We
wished to explore a variety of amines as potential piper-
azine surrogates. Binding affinities were determined
using a stably transfected Chinese hamster ovary
(CHO) cell line expressing 5HT1B receptors. The com-
pounds were evaluated in competition assays using
[3H]-GR125743 and Ki values were determined as descri-
bed.5d,13 It is interesting to note that homopiperazine 7a
is more active than the corresponding piperazine deriv-
ative 7c (Table 1). Replacement of either the homopiper-
azine or piperazine with an analogous, noncyclic amine
(7b and 7d, respectively) resulted in significant loss of
activity, indicating that the rigidity of the cyclic amine
was required in these systems. The chirality of the
amines also appeared to be important as exemplified
by 7e and 7f. The (3R)-(+)-3-(dimethylamino)-pyrroli-
dine derivative 7e demonstrated potent activity while
the (S)-enantiomer 7f was inactive. To our knowledge,
such strong chirality effects have not been previously
reported opposite the 5HT1B receptor. The N,N0dieth-
The quinoline compounds 18a–c (Table 2) were expected
to exhibit better DMPK properties than the quinolones
allowing for better blood–brain barrier penetration and
subsequent oral bioavailability due to their reduced
polar surface area16 and decreased basicity. In the
quinoline series, the piperazine side chain at the 8-posi-
tion was held constant and the functional group at the
4-position was examined (Table 2). Replacement of the
carbonyl of the quinolones with an N,N-dimethylamino
group (7c vs 18a) resulted in a diminution of activity.
The N-methyl amino derivative 18b was inactive, imply-
ing that the presence of a hydrogen-bond donor at the
4-position is detrimental to binding. This is also consis-
tent with the decreased basicity of the quinoline nitrogen
of 18a relative to 18b due to unfavorable peri–steric
interactions, which result in poor orbital overlap of
the periplanar dimethyl amino group with the p orbitals
of the ring system. Subsequently, the electron density at
the quinoline nitrogen in 18a is decreased versus 18b.17
Consistent with this hypothesis, the even less basic meth-
oxy compound 18c18 demonstrated improved activity
over 18a. The intrinsic affinity of 18c was determined
to be ꢀ28 using the GTPcS binding assay, demonstrat-
ing this compound to be a full antagonist. It is believed
that the quinoline compounds may have better physical
properties. At present, activity in the guinea pig hypo-
thermia model remains to be determined for quinoline
18c; a positive outcome in this test would be consistent
with achievement of CNS penetration.
OMe
O
F
F
a
b
O
O
N
N
H
Br
O
Br
O
19
9
OMe
OMe
N
F
F
d
H
N
OR
N
N
N
O
N
N
O
N
O
18c
R=Me, 20
R=OH, 21
c
Scheme 3. Synthesis of 6-fluoro-4-methoxy-8-(4-methyl-piperazin-1-
yl)-quinoline-2-carboxylic acid (4-morpholin-4-yl-phenyl)amide
(18c). Reagents and conditions: (a) 1.1 equiv NaH, 1.2 equiv
CH3I, NMP, 2 h, 98% or 1.5 equiv K2CO3, 2 equiv CH3I, DMSO,
70 ꢁC, 1 h, 93%; (b) 1.1 equiv N-methyl piperizine, 2 mol%
3. Conclusions
˚
Pd2(dba)3, 0.12 equiv BINAP, 1.4 equiv Cs2CO3, 4 A molecular
We have developed robust synthetic routes to the
desired quinolones and quinolines. In both cases, the
routes are suitable for MPS and late-stage diversifica-
tion at the 4- and/or 8-position. Diversification of the
sieves, toluene, reflux, 36 h, 90%; (c) 1.1 equiv LiOHÆH2O,
THF:MeOH:H2O, RT, 1 h, 95%; (d) 1.2 equiv 4-morpolinoaniline,
2.0 equiv TBTU, 2.0 equiv HOBt, 4.0 equiv DIEA, DMF, RT,
18 h, 93%.

C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
943
compounds at the amide position is feasible as well. The
quinolones and quinolines have proven to be potent new
5HT1B antagonists. Preliminary SAR has revealed new
areas for optimization of these compounds. The binding
affinities seen within the relatively small subset of poten-
tial cyclic amines tested for the quinolone series suggest
that a variety of amines may potentially serve as surro-
gates for the traditional piperazine side chain. The
homopiperazine appears to be particularly promising.
The pyrrolidine examples provide new evidence that
the chirality of the amines may have dramatic effects
on 5HT1B receptor binding affinity.
110 and 1100 Da in 1 s (total cycle time was 1.1 s) using a
cone voltage of 30 V. The resultant mass spectra were cen-
tered by setting the measured mass for the Leu-Enkepha-
lin protonated molecular ion to its known accurate mass
of 556.2766 Da. This yielded accurate mass determina-
tions for the analyte related mass spectral ions.
4.2. Synthesis of quinolines 7a–7h
4.2.1. 2-(2-Bromo-4-methoxyphenylamino)-but-2-enedioic
acid dimethyl ester (1). A solution of 2-bromo-4-meth-
oxy aniline (6.02 g, 29.8 mmol) in 125 mL anhydrous
methanol was treated with dimethyl acetylenedicarboxy-
late (3.70 mL, 30.2 mmol) and the solution was heated
at reflux under nitrogen for 8 h. The reaction mixture
was cooled, concentrated, and dissolved in hot metha-
nol. Yellow crystals were obtained by filtration (6.93 g,
68%). A second crop of crystals was obtained from eth-
anol (0.942 g, 9%). The filtrates were combined and
purified by flash chromatography on silica gel using
4:1 hexanes/ethyl acetate to afford an additional 1.63 g
4. Experimental
4.1. General methods
All chemicals were reagent grade and were used without
further purification. Solvents were HPLC (high perfor-
mance liquid chromatography) or anhydrous grade.
Reactions were performed under inert (N2) atmosphere.
Column chromatography was performed manually or
on an ISCO CombiFlashꢂ Optix 10. Proton and carbon
nuclear magnetic resonance (NMR) spectra were ac-
quired on a Bruker Avance 300 spectrometer using a
5 mm QNP probe operating at 300.13 MHz for proton
and 75.5 MHz for carbon-13 or a Bruker Avance 400
spectrometer using a 5 mm inverse broadband probe
operating at 400.13 MHz for proton and 100.6 MHz for
carbon-13. For advanced experiments, NMR spectra
were acquired on a Bruker Avance 500 spectrometer using
the 5 mm Bruker triple resonance cryogenically cooled
probe (Cryoprobeꢂ) equipped with Z-gradient. Proton
spectra were acquired at 500.13 MHz and carbon-13
assignments were made based on two- and three-bond
proton-carbon couplings observed in 2D HMBC spectra.
The heteronuclear multiple bond correlation (HMBC)
experiments were typically run on a sample with less than
1 mg of compound dissolved in 0.6 mL CDCl3, using a
gradient pulse sequence. The enhanced sensitivity of the
Cryoprobeꢂ allowed acquisition of the HMBC data in
less than 30 min. The same level of signal using the Avance
400 conventional probe required more than 6 h of acqui-
sition time. Low resolution mass spectra were obtained on
a Micromass LCZ using an APCI (atmospheric pressure
chemical ionization) detection mode and a Zorbax
50 mm · 2.1 mm Stablebond C8 column with a solvent
gradient of 5% B to 90% B over 4 min at 1.4 mL/min
where solvent A = 0.05% TFA in H2O and solvent
B = 90% CH3CN/10% H2O/0.05% TFA. High resolution
electrospray mass spectrometric data were acquired by di-
rect infusion of the compounds in DMSO or MeOH solu-
1
(16%) of product for a total yield of 93%. H NMR
(300 MHz, DMSO-d6) d 9.60 (s, 1H, NH), 7.26 (d, 1H,
Jm = 2.7 Hz, ArH3), 6.93 (dd, 1H, Jo = 8.7, Jm = 2.7 Hz,
ArH5), 6.87 (d, 1H, Jo = 8.7 Hz, ArH6), 5.34 (s, 1H,
C@CH), 3.76 (s, 3H, OCH3), 3.68 (s, 3H, CHCO2CH3),
3.66 (s, 3H, CNCO2CH3); Mass Spec.: Calcd for
[C13H14BrNO5 + H]+
Obs. = 344, 346.
Theor.
m/z = 344,
346;
4.2.2. 8-Bromo-6-methoxy-4-oxo-1,4-dihydroquinoline-2-
carboxylic acid methyl ester (2). DowThermꢀ
(175 mL) was heated to 244 ꢁC and (9.50 g,
A
1
27.6 mmol) was added as a solid in portions over
7 min while maintaining a temperature of 230–240 ꢁC.
The brown reaction mixture was heated at 240–245 ꢁC
for 45 min and then cooled to room temperature. A yel-
low precipitate formed upon cooling. Approximately
100 mL of hexanes was added to the mixture and the
solids were isolated by filtration, washed with additional
hexanes, and dried under high vacuum to afford the
product as a yellow solid (6.73 g, 78%). 1H NMR
(300 MHz, DMSO, d6) d 12.01 (s, 1H, NH), 7.86 (d,
1H, Jm = 2.7 Hz, ArH5), 7.52 (s, 1H, C@CH), 7.48 (d,
1H, Jm = 2.7 Hz, ArH7), 3.93 (s, 6 H, OCH3 and
CO2CH3); Mass Spec.: Calcd for [C12H10BrNO4 + H]+
Theor. m/z = 312, 314; Obs. = 312, 314.
4.2.3. 8-Bromo-6-methoxy-4-oxo-1,4-dihydroquinoline-2-
carboxylic acid (3). To a solution of 2 (3.53 g,
11.3 mmol) in 75 mL 3:1:1 tetrahydrofuran/methanol/
water was added lithium hydroxide monohydrate
(1.367 g, 32.6 mmol). The reaction mixture was stirred
at room temperature for 5 h. The reaction mixture was
concentrated and then poured into water. The solution
was acidified to pH 2 with 1 N HCl and the resulting sol-
ids were isolated by filtration. The solids were then sus-
pended in methanol and filtered to afford the desired
product as a pale yellow solid (2.673 g, 80%). An addi-
tional 0.577 g (17%) of product was isolated from the
methanol filtrates. 1H NMR (300 MHz, DMSO-d6,
TFA Shake) d 7.86 (d, 1H, Jm = 2.7 Hz, ArH5), 7.55
(d, 1H, Jm = 2.7 Hz, ArH7), 7.32 (s, 1H, C@CH), 3.94
tion (20 lg/mL) on
a Micromass QTOF-1 mass
spectrometer operated in the positive ionization mode.
The compounds were diluted with a solution containing
Leucine Enkephalin (approximately 25 lg/mL) dissolved
in water/MeOH (3:7). The infusion rate was 5 ll/min and
the positioning of the electrospray probe was adjusted
such that the signal abundances of the protonated molec-
ular ions from the analytes and the lock mass (Leu-En-
kephalin) were not subject to dead time correction. The
instrument was scanned, in the continuum mode, between

944
C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
(s, 3H, OCH3); Mass Spec.: Calcd for [C11H8BrNO4 + H]+
Theor. m/z = 298, 300; Obs. = 298, 300.
sieves in 30 mL anhydrous toluene were added tris(dib-
enzylidineacetone)dipalladium(0) (Pd2(dba)3) (90.0 mg,
0.098 mmol) and racemic 2,20-bis(diphenylphosphino)-
1,10-binaphthyl (BINAP) (0.358 g, 0.58 mmol). The
resulting reddish brown mixture became lighter in color
upon treatment with cesium carbonate (2.544 g,
7.81 mmol). The reaction mixture was heated at reflux
under nitrogen for 17 h. The clear brown solution was
cooled to room temperature, concentrated, and then
purified by flash chromatography on silica gel using a
slow gradient of 95:5 to 50:50 methylene chloride:meth-
4.2.4. 8-Bromo-6-methoxy-4-oxo-1,4-dihydroquinoline-2-
carboxylic acid (4-morpholin-4-yl-phenyl)amide (4). To a
yellow suspension of 3 (3.446 g, 11.56 mmol), 2-(1H-
benzotriazole-1-yl)-1,1,3,3-tetramethyluronium-tetra-
fluoroborate (TBTU) (9.039 g, 28.15 mmol), and 1-
hydroxybenzotriazole
hydrate
(HOBt)
(3.757 g,
27.8 mmol) in 100 mL dimethylformamide (DMF) were
added 4-morpholinoaniline (2.733 g, 15.3 mmol) and
DIEA (8.2 mL, 50.2 mmol). The resulting maroon solu-
tion was stirred at room temperature under nitrogen for
16 h during which time the reaction became greenish
brown and formed a large amount of precipitate. The
reaction mixture was filtered and the solids washed with
DMF, water, and methanol. Drying under high vacuum
afforded the desired product as a yellow solid (3.09 g,
1
anol to afford the desired product (0.989 g, 81%). H
NMR (300 MHz, DMSO-d6) d 9.88 (s, 1H, NH), 7.73
(s, 1H, ArH3), 7.68 (d, 2H, Jo = 8.9 Hz,
0
0
ArH2 and H6 ),
7.00
(d,
2H,
Jo = 8.9 Hz,
0
0
ArH3 and H5 ), 6.94 (d, 1H, Jm = 2.7 Hz, ArH5), 6.66
(d, 1H, Jm = 2.7 Hz, ArH7), 5.62 (s, 2H, OCH2O), 3.87
(s, 3H, OCH3), 3.80 (t, 2H, J = 8.0 Hz, OCH2CH2Si),
3.73 (t, 4H, J = 4.7 Hz, OCH2CH2N), 3.63 (t, 2H,
J = 5.9 Hz, ArNCH2CH2CH2NCH3), 3.33 (br s, 2H,
ArNCH2CH2NCH3), 3.09 (t, 4H, J = 4.7 Hz,
OCH2CH2N), 2.97 (br s, 2H, ArNCH2CH2NCH3),
2.69 (br s, 2H, ArNCH2CH2CH2NCH3), 2.35 (s, 3H,
NCH3), 2.09 (br s, 2 H ArNCH2CH2CH2NCH3), 0.94
(t, 2H, J = 8.0 Hz, OCH2CH2Si), ꢀ0.03 (s, 9H,
Si(CH3)3); Mass Spec.: Calcd for [C33H47N5O5Si + H]+
Theor. m/z = 622; Obs. = 622.
1
58%). H NMR (300 MHz, DMSO-d6) d 12.13 (s, 1H,
NH), 10.18 (s, 1H, C(O)NH), 7.90 (d, 1H, Jm = 2.7 Hz,
0
0
ArH5), 7.68 (d, 2H, Jo = 9.0 Hz, ArH2 and H 6 ), 7.63
(s, 1H, C@CH), 7.51 (d, 1H, Jm = 2.7 Hz, ArH7), 7.00
0
0
(d, 2H, Jo = 9.0 Hz, ArH3 and H5 ), 3.94 (s, 3H,
OCH3), 3.75 (t, 4H, J = 4.8 Hz, OCH2CH2N), 3.10 (t,
4H, J = 4.8 Hz, OCH2CH2N); Mass Spec.: Calcd for
[C21H20BrN3O4 + H]+ Theor. m/z = 458, 460; Obs. =
458, 460.
4.2.5. 8-Bromo-6-methoxy-4-(2-trimethylsilanylethoxy-
methoxy)-quinoline-2-carboxylic acid (4-morpholin-4-yl-
phenyl)amide (5). A yellow suspension of 4 (3.092 g,
6.75 mmol) in 40 mL N-methylpyrrolidinone (NMP)
was treated with sodium hydride (60% dispersion in
oil, 0.410 g, 10.24 mmol). Gas evolution and warming
were observed and the suspension became light brown
and almost clear. The reaction mixture was stirred for
10 min at room temperature under nitrogen. Addition
of 2-(trimethylsilyl)ethoxymethyl chloride (1.6 mL,
9.1 mmol) resulted in a slightly cloudy, lighter brown
solution. After 4.5 h at room temperature, the reaction
mixture was poured into 300 mL water, stirred for
15 min, and then stored at 0 ꢁC overnight. The solids
were isolated by filtration, suspended in methanol, fil-
tered again, and dried under high vacuum to afford
4.2.7. 6-Methoxy-8-(4-methyl-[1,4]diazepan-1-yl)-4-oxo-
1,4-dihydroquinoline-2-carboxylic acid (4-morpholin-4-
yl-phenyl)amide (7a).
A solution of 6a (0.989 g,
1.59 mmol) in 20 mL methanol was poured into 300 mL
0.05 N hydrochloric acid. The clear dark yellow solution
became cloudy within 5 min. The mixture was stirred at
room temperature for 45 min and then adjusted to pH 7
with 10% sodium hydroxide. The resulting yellow precip-
itate was isolated by filtration, washed with water, and
dried under high vacuum to afford the desired product
1
as a yellow solid (0.629 g, 80%). H NMR (300 MHz,
DMSO-d6) d 9.97 (br s, 1H, C(O)NH), 7.67 (d, 2H,
0
0
Jo = 8.8 Hz, ArH2 and H6 ), 7.47 (br s, 1H, ArH5), 7.00
(s, 1H, C@CH), 6.99 (d, 2H, Jo = 8.8 Hz,
0
0
ArH3 and H5 ), 6.71 (br s, 1H, ArH7), 3.85 (s, 3H,
OCH3), 3.75 (t, 4H, J = 4.6 Hz, OCH2CH2N), 3.70 (br
s, 2H, ArNCH2CH2CH2NCH3), 3.55 (br s, 2H,
ArNCH2CH2NCH3), 3.09 (t, 4H, J = 4.6 Hz,
OCH2CH2N), 2.95 (br s, 2H, ArNCH2CH2NCH3), 2.73
(br s, 2H, ArNCH2CH2CH2NCH3), 2.36 (s,
3H, NCH3), 2.07 (br s, 2H, ArNCH2CH2CH2NCH3);
Mass Spec.: Calcd for [C27H33N5O4 + H]+ Theor.
1
the product as a yellow solid (3.19 g, 80%). H NMR
(300 MHz, DMSO-d6) d 10.18 (s, 1H, C(O)NH), 7.95
(d, 1H, Jm = 2.4 Hz, ArH7), 7.83 (s, 1H, ArH3), 7.69
0
0
(d, 2H, Jo = 9.0 Hz, ArH2 and H6 ), 7.51 (d, 1H,
Jm = 2.7 Hz, ArH5), 7.00 (d, 2H, Jo = 9.0 Hz,
0
0
ArH3 and H5 ), 5.69 (s, 2H, OCH2O), 3.95 (s, 3H,
OCH3), 3.85 (t, 2H, J = 8.0 Hz, OCH2CH2Si), 3.75 (t,
4H, J = 4.7 Hz, OCH2CH2N), 3.10 (t, 4H, J = 4.7 Hz,
OCH2CH2N), 0.94 (t, 2H, J = 8.0 Hz, OCH2CH2Si),
ꢀ0.04 (s, 9 H, Si(CH3)3); Mass Spec.: Calcd for
m/z = 492.2605;
Obs. = 492.2616.
Analysis
for
C27H33N5O4Æ1.0HClÆ0.3H2O: Calculated C, 60.79; H,
6.54; N, 13.13. Found C, 60.82; H, 6.53; N, 13.17.
[C27H34BrN3O5Si + H]+
Theor.
m/z = 588,
590;
4.3. Alternate Synthesis of 7a
Obs. = 588, 590. 2D HMBC: H3 and H5 correlate with
C4; OCH2O correlate with C4.
4.3.1. 8-Bromo-6-methoxy-4-(2-trimethylsilanylethoxy-
methoxy)-quinoline-2-carboxylic acid methyl ester (13).
A brown solution of 2 (6.73 g, 21.6 mmol) in 100 mL N-
methylpyrrolidinone was treated with sodium hydride
(60% dispersion in oil, 1.028 g, 25.7 mmol). Gas
evolution and warming were observed. The reaction
mixture was stirred for 10 min at room temperature
4.2.6. 6-Methoxy-8-(4-methyl-[1,4]diazepan-1-yl)-4-(2-
trimethylsilanylethoxymethoxy)-quinoline-2-carboxylic
acid (4-morpholin-4-yl-phenyl)amide (6a). To a yellow-
green suspension of 5 (1.155 g, 1.96 mmol), N-methylho-
˚
mopiperazine (0.39 mL, 3.14 mmol), and 4 A molecular

C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
945
under nitrogen. Addition of 2-(trimethylsilyl)ethoxym-
ethyl chloride (SEM-Cl) (5.00 mL, 28.3 mmol) resulted
in a slightly cloudy, light brown solution. After 2.5 h
at room temperature, the reaction mixture was poured
into 800 mL water and stirred for 15 min. The resulting
precipitate was isolated by filtration, washed with water,
and dried under high vacuum to afford the product as a
cream colored solid (9.70 g, quantitative yield). 1H
NMR (300 MHz, DMSO-d6) d 7.97 (d, 1H, Jm = 2.7 Hz,
ArH7), 7.79 (s, 1H, C@CH), 7.53 (d, 1H, Jm = 2.7 Hz,
ArH5), 5.70 (s, 2H, OCH2O), 3.99 (s, 6H, OCH3 and
CO2CH3), 3.88 (t, 2H, J = 8.0 Hz, OCH2CH2Si), 0.97
(t, 2H, J = 8.0 Hz, OCH2CH2Si), ꢀ0.04 (s, 9H,
Si(CH3)3); Additional 2D NMR data were used to con-
firm regioselectivity. HMBC experiments confirmed the
proton and carbon assignments and the presence of pro-
ton–carbon coupling between the OCH2O of the SEM
group and the C4 of the quinoline ring system which
can only be present with O-alkylation.; Mass Spec.:
Calcd for [C18H24BrNO5Si + H]+ Theor. m/z = 442,
444; Obs. = 442, 444. Analysis for C18H24BrNO5SiÆ0.15-
H2O: Calculated C, 48.57; H, 5.50; N, 3.15. Found C,
48.09; H, 4.94; N, 3.21.
7.00 (d, 1H, Jm = 2.4 Hz, ArH5), 6.70 (d, 1H,
Jm = 2.4 Hz, ArH7), 4.05–3.99 (m, 2H, ArNCH2
CH2CH2NCH3), 3.87 (s, 3H, OCH3), 3.68–3.60 (m,
2H, ArNCH2CH2NCH3), 3.54–3.47 (m, 2H, ArNCH2
CH2NCH3), 3.41–3.26 (m, 2H, ArNCH2CH2CH2NCH3),
2.82 (d, 3H, J = 4.8 Hz, NCH3), 2.46-2.41 (m, 1H,
ArNCH2CH2CH2NCH3), 2.30–2.25 (m, 1H ArNCH2-
CH2CH2NCH3); Mass Spec.: Calcd for [C17H21
N3O4 + H]+ Theor. m/z = 332; Obs. = 332.
4.3.4. 6-Methoxy-8-(4-methyl-[1,4]diazepan-1-yl)-4-oxo-
1,4-dihydroquinoline-2-carboxylic acid (4-morpho-lin-4-
yl-phenyl)amide (7a). To a solution of 15 (2.10 mmol)
and DIEA (1.4 mL, 8.6 mmol) in DMF (34 mL) were
added TBTU (1.40 g, 4.36 mmol) and HOBt (0.588 g,
4.35 mmol) followed by the addition of 4-morphol-
inoaniline (0.463 g, 2.60 mmol). The resulting dark
brown solution was stirred at room temperature under
nitrogen for 19 h. The reaction mixture was concentrat-
ed in vacuo and the crude product was taken up in
methylene chloride/methanol. Filtration of the resulting
mixture afforded some product as a yellow solid. The fil-
trates were concentrated and partitioned between meth-
ylene chloride and saturated aqueous sodium
bicarbonate. The organic layer was washed with saturat-
ed sodium bicarbonate, dried over MgSO4, filtered, and
concentrated under vacuum to afford a brown solid.
This was suspended in methanol and filtered to afford
the desired product as a yellow solid (0.714 g, 69%).
1H NMR (300 MHz, DMSO-d6) d 9.97 (br s, 1H,
4.3.2. 6-Methoxy-8-(4-methyl-[1,4]diazepan-1-yl)-4-(2-
trimethylsilanylethoxymethoxy)-quinoline-2-carboxylic
acid methyl ester (14). To a clear, light brown solution of
13 (1.01 g, 2.28 mmol), N-methylhomopiperazine
˚
(0.32 mL, 2.57 mmol), and 4 A molecular sieves in
30 mL anhydrous toluene were added Pd2(dba)3
(43.8 mg, 0.048 mmol) and BINAP (169.8 mg,
0.27 mmol). The resulting wine colored solution was
treated with cesium carbonate (1.124 g, 3.45 mmol).
The reaction mixture was heated at reflux under nitro-
gen for 21 h. The resulting pea green reaction mixture
was cooled to room temperature and concentrated.
The crude mixture was purified by flash chromatogra-
phy on silica gel using a gradient of 95:5 to 40:60 meth-
ylene chloride/methanol to afford the desired product as
a yellow foam (1.004 g, 92%). 1H NMR (300 MHz,
DMSO-d6) d 7.67 (s, 1H, ArH3), 6.94 (d, 1H,
Jm = 2.4 Hz, ArH5), 6.66 (d, 1H, Jm = 2.4 Hz, ArH7),
5.60 (s, 2H, OCH2O), 3.94 (s, 3H, CO2CH3), 3.88 (s,
3H, OCH3), 3.82 (t, 2H, J = 8.0 Hz, OCH2CH2Si),
3.75 (br s, 4H, ArNCH2CH2CH2NCH3 and ArNCH2-
CH2NCH3), 3.45 (br s, 2H, ArNCH2CH2NCH3), 3.31
(br s, 2H, ArNCH2CH2CH2NCH3), 2.83 (s, 3H,
NCH3), 2.28 (br s, 2H, ArNCH2CH2CH2NCH3), 0.92
(t, 2H, J = 8.0 Hz, OCH2CH2Si), ꢀ0.04 (s, 9H,
Si(CH3)3); Mass Spec.: Calcd for [C24H37N3O5Si + H]+
Theor. m/z = 476; Obs. = 476.
0
NH), 7.67 (d, 2H, Jo = 8.8 Hz, ArH2 and H60), 7.47
(br s, 1H, ArH5), 7.00 (s, 1H, C@CH), 6.99 (d, 2H,
0
0
Jo = 8.8 Hz, ArH3 and H5 ), 6.71 (br s, 1H, ArH7),
3.85 (s, 3H, OCH3), 3.75 (t, 4H, J = 4.6 Hz,
OCH2CH2N), 3.70 (br s, 2H, ArNCH2CH2CH2NCH3),
3.55 (br s, 2H, ArNCH2CH2-NCH3), 3.09 (t, 4H,
J = 4.6 Hz,
OCH2CH2N),
2.95
(br
s,
2H,
ArNCH2CH2NCH3), 2.73 (br s, 2H, ArNCH2CH2
CH2NCH3), 2.36 (s, 3H, NCH3), 2.07 (br s, 2H,
ArNCH2CH2CH2NCH3); Mass Spec.: Calcd for
[C27H33N5O4 + H]+ Theor. m/z = 492; Obs. = 492.
4.3.5.
8-[(3-Dimethylamino-propyl)-methyl-amino]-6-
methoxy-4-oxo-1,4-dihydroquinoline-2-carboxylic acid
(4-morpholin-4-yl-phenyl)amide (7b). The title compound
was prepared from 5 in the same manner as described
for 7a using N,N,N0-trimethyl-1,3-propanediamine for
the Buchwald–Hartwig coupling except that the SEM
deprotection was carried out using 1.0 M HCl in ether
(30 mL). The product precipitated from the reaction
mixture and was isolated by filtration and washed with
ether to afford the title compound as a cream colored
1
4.3.3. 6-Methoxy-8-(4-methyl-[1,4]diazepan-1-yl)-4-oxo-
1,4-dihydroquinoline-2-carboxylic acid (15). To a light
brown solution of 14 (1.00 g, 2.10 mmol) in 18 mL
3:1:1 tetrahydrofuran/methanol/water was added lithi-
um hydroxide monohydrate (0.267 g, 6.35 mmol). The
reaction mixture was stirred at room temperature for
5 h, acidified to pH 4 with 1 N HCl, and stirred an addi-
tional 20 min. The reaction mixture was concentrated
and dried under high vacuum to afford an orange solid
(0.97 g, quantitative yield). 1H NMR (300 MHz,
DMSO-d6) d 11.06 (s, 1H, NH), 7.53 (s, 1H, C@CH),
solid (0.264 g, 62% yield from 5). H NMR (300 MHz,
DMSO-d6/CF3CO2D) 8.26 (d, 2H, Jo = 8.9 Hz,
0
0
ArH2 and H6 ), 8.19 (s, 1H, ArH5), 7.85 (s, 1H,
C@CH), 7.67 (s, 1H, ArH7), 7.59 (d, 2H, Jo = 8.9 Hz,
0
0
ArH3 and H5 ), 4.03 (s, 3H, OCH3), 3.97 (br s, 4H,
OCH2CH2N), 3.89 (t, 2H, J = 7.2 Hz, ArNCH2CH2),
3.54 (br s, 4H, OCH2CH2N), 3.46 (s, 3H, ArNCH3),
3.15 (t, 2H, J = 7.2 Hz, CH2CH2N(CH3)2), 2.69
(s, 6H, CH2N(CH3)2), 1.91 (br s, 2H, ArNCH2
CH2CH2 N(CH3)2); Mass Spec.: Calcd for [C27H35
N5O4 + H]+ Theor. m/z = 494; Obs. = 494. Analysis for

946
C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
C27H35-N5O4Æ3.1HClÆ2.15H2O: Calculated C, 50.25; H,
6.62; N, 10.82. Found C, 50.28; H, 6.67; N, 10.79.
Calcd for [C27H33N5O4 + H]+ Theor. m/z = 492.2605;
Obs. = 492.2608. Analysis for C27H33N5O4Æ3.6HClÆ0.01-
H2O: Calculated C, 51.92; H, 5.94; N, 11.21. Found C,
51.99; H, 5.88; N, 11.15.
4.3.6. 6-Methoxy-8-(4-methyl-piperazin-1-yl)-4-oxo-1,4-
dihydroquinoline-2-carboxylic acid (4-morpholin-4-yl-
phenyl)amide (7c). The title compound was prepared
from 2 as described in the alternate synthesis for 7a
(see above). The desired product was obtained as a yel-
low solid (0.144 g, 43% yield from 15). 1H NMR
(300 MHz, DMSO-d6/CF3CO2D) 7.90 (d, 2H,
4.3.9.
methoxy-4-oxo-1,4-dihydroquinoline-2-carboxylic
8-((3S)-(ꢀ)-3-Dimethylamino-pyrrolidin-1-yl)-6-
acid
(4-morpholin-4-yl-phenyl)amide (7f). The title compound
was prepared from 5 in the same manner as described
for 7e using (3S)-(ꢀ)-3-(dimethylamino)-pyrrolidine for
the Buchwald–Hartwig coupling. The desired product
was obtained as a yellow solid (0.178 g, 56% yield from
0
0
Jo = 8.9 Hz, ArH2 and H6 ), 7.59 (s, 1H, C@CH), 7.36
0
0
(d, 2H, Jo = 8.9 Hz, ArH3 and H5 ), 7.19 (d, 1H,
Jm = 2.4 Hz, ArH5), 6.95 (d, 1H, Jm = 2.4 Hz, ArH7),
4.09 (t, 2H, J = 11.6 Hz, ArNCH2CH2N), 3.91 (s, 3H,
OCH3), 3.89 (t, 4H, d, 1H, J = 5.4 Hz, OCH2CH2N),
3.66 (t, 2H, J = 11.6 Hz, ArNCH2CH2N), 3.52 (t, 2H,
J = 11.6 Hz, ArNCH2CH2N), 3.38 (t, 4H, J = 5.4 Hz
OCH2CH2N), 3.18 (t, 2H, J = 11.6 Hz, ArNCH2CH2N),
2.97 (s, 3H, NCH3); Mass Spec.: Calcd for [C26H31
N5O4 + H]+ Theor. m/z = 478.2449; Obs. = 478.2440.
Analysis for C26H31N5O4Æ0.2HCl: Calculated C,
64.41H 6.49; N, 14.44. Found C, 64.49; H, 6.29; N,
14.42.
1
5). H NMR (300 MHz, DMSO-d6/CF3CO2D) 8.03 (d,
0
0
2H, Jo = 9.0 Hz, ArH2 and H6 ), 7.63 (d, 2H,
0
0
Jo = 9.0 Hz, ArH3 and H5 ), 7.59 (s, 1H, C@CH), 7.00
(s, 1H, ArH5), 6.65 (s, 1H, ArH7), 4.24-3.91 (m, 6H,
ArNCH2CH(N)CH2CH2), 4.00 (br s, 4H, OCH2CH2N),
3.91 (s, 3H, OCH3), 3.55 (br s, 4H, OCH2CH2N),
2.93 (d, 6H, J = 3.9 Hz, NCH3)2), 2.35-2.29 (m, 1H,
CHN(CH3)2);
Mass
Spec.:
Calcd
for
[C27H33N5O4 + H]+ Theor. m/z = 492.2605; Obs. =
492.2616. Analysis for C27H33N5O4Æ3.0HClÆ0.3H2O:
Calculated C, 53.48; H, 6.08; N, 11.55. Found C,
53.52; H, 6.11; N, 11.51.
4.3.7. 8-[(2-Dimethylamino-ethyl)-methyl-amino]-6-meth-
oxy-4-oxo-1,4-dihydroquinoline-2-carboxylic acid (4-
morpholin-4-yl-phenyl)amide (7d). The title compound
was prepared from 5 in the same manner as described
for 7b using N,N,N0-trimethyl ethylene diamine for the
Buchwald–Hartwig coupling. The desired product was
obtained as a light yellow solid (0.269 g, 77% yield from
4.3.10. 8-[Ethyl-(1-ethyl-pyrrolidin-3-yl)-amino]-6-meth-
oxy-4-oxo-1,4-dihydroquinoline-2-carboxylic acid (4-
morpholin-4-yl-phenyl)amide (7g). The title compound
was prepared from 5 in the same manner as described
for 7b using 3-diethylaminopyrrolidine for the Buch-
wald–Hartwig coupling. A final trituration in diethyl
ether containing a small amount of methanol followed
by filtration and washing with ether afforded the desired
1
5). H NMR (300 MHz, DMSO-d6/CF3CO2D) 8.10 (d,
0
0
2H, Jo = 8.4 Hz, ArH2 and H6 ), 7.69 (s, 1H, ArH5),
7.61 (s, 1H, C@CH), 7.55 (d, 2H, Jo = 8.4 Hz,
1
product as a beige solid (0.163 g, 37% yield from 5). H
NMR (300 MHz, DMSO-d6/CF3CO2D) 8.03 (d, 2H,
0
0
ArH3 and H5 ), 7.44 (s, 1H, ArH7), 4.01 (t, 2H,
J = 6.6 Hz, ArNCH2CH2N), 3.98 (br s, 4H,
OCH2CH2N), 3.98 (s, 3H, OCH3), 3.51 (br s, 4H,
OCH2CH2N), 3.43 (t, 2H, J = 6.6 Hz, ArNCH2CH2N),
3.24 (s, 3H, ArNCH3), 2.83 (s, 6H, CH2N(CH3)2); Mass
Spec.: Calcd for [C26H33N5O4 + H]+ Theor. m/z = 480;
Obs. = 480. Analysis for C26H33N5O4Æ3.15HClÆ1.7H2O:
Calculated C, 49.96; H, 6.38; N, 11.20. Found C,
49.94; H, 6.39; N, 11.17.
0
0
Jo = 9.0 Hz, ArH2 and H6 ), 7.65 (d, 2H, Jo = 9.0 Hz,
0
0
ArH3 and H5 ), 7.58 (s, 1H, C@CH), 6.99 (s, 1H,
ArH5), 6.23 (s, 1H, ArH7), 4.23–4.05 (m, 3H,
ArNCHCH2
& ArNCHCH2N), 4.01 (br s, 4H,
OCH2CH2N), 3.91 (s, 3H, OCH3), 3.90 (br s, 2H,
ArNCHCH2CH2N), 3.58 (br s, 4H, OCH2CH2N),
3.46–3.40 (m, 2H, ArNCH2CH3), 3.27–3.22 (m, 2H,
NCH2CH3), 2.31 (br s, 2H, ArNCHCH2CH2N), 1.28
(t, 3H, J = 7.2 Hz, ArNCH2CH3), 1.24 (t, 3H,
J = 7.2 Hz, NCH2CH3); Mass Spec.: Calcd for
[C29H37N5O4 + H]+ Theor. m/z = 520.2918; Obs. =
520.2907. Analysis for C29H37N5O4Æ4.00HClÆ0.35Et2O:
Calculated C, 52.81; H, 6.49; N, 10.13. Found C,
52.81; H, 6.24; N, 9.89.
4.3.8.
methoxy-4-oxo-1,4-dihydroquinoline-2-carboxylic
8-((3R)-(+)-3-Dimethylamino-pyrrolidin-1-yl)-6-
acid
(4-morpholin-4-yl-phenyl)amide (7e). The title compound
was prepared from 5 in the same manner as described
for 7b using (3R)-(+)-3-(dimethylamino)pyrrolidine for
the Buchwald–Hartwig coupling. A final trituration in
methylene chloride containing a small amount of meth-
anol followed by filtration and washing with methylene
chloride afforded the desired product as a yellow solid
(0.190 g, 59% yield from 5). 1H NMR (300 MHz,
DMSO-d6/CF3CO2D) 10.72 (br s, <1H, CH@CNH),
10.33 (br s, <1H, C(O)NH), 8.07 (d, 2H, Jo = 9.0 Hz,
4.3.11. 6-Methoxy-8-[methyl-(1-methyl-pyrrolidin-3-yl)-
amino]-4-oxo-1,4-dihydroquinoline-2-carboxylic acid (4-
morpholin-4-yl-phenyl)amide (7h). The title compound
was prepared from 5 in the same manner as described
for 7g using N,N0-dimethyl-3-aminopyrrolidine for the
Buchwald–Hartwig coupling except that the hydroscop-
ic material was dissolved in methanol, stirred in the pres-
ence of potassium carbonate, filtered, and concentrated
to dryness prior to the trituration in diethyl ether. This
yielded a brown solid which was purified on silica gel
using a gradient of 100:0 to 80:20 methylene chlo-
ride:methanol as an eluent. After a final trituration in
0
0
ArH2 and H6 ),
7.69
(d,
2H,
Jo = 9.0 Hz,
0
0
ArH3 and H5 ), 7.61 (s, 1H, C@CH), 7.03 (d, 1H,
Jm = 2.4 Hz, ArH5), 6.71 (br s, 1H, ArH7), 4.28-3.91
(m, 6H, ArNCH2CH(N)CH2CH2), 4.03 (t, 4H,
J = 4.4 Hz, OCH2CH2N), 3.91 (s, 3H, OCH3), 3.57 (t,
4H, J = 4.4 Hz, OCH2CH2N), 2.92 (d, 6H, J = 5.7 Hz,
NCH3)2), 2.42–2.32 (m, 1H, CHN(CH3)2); Mass Spec.:

C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
947
methanol, the desired product was obtained as a yellow
solid (0.024 g, 13% yield from 5). H NMR (300 MHz,
C11H7BrFNO3: Calculated C 44.03; H, 2.35; N, 4.67.
Found C, 44.14; H, 2.14; N, 4.70.
1
DMSO-d6/CF3CO2D) 7.95 (d, 2H, Jo = 9.0 Hz,
0
0
ArH2 and H6 ), 7.57 (s, 1H, C@CH), 7.47 (d, 2H,
4.4.3.
8-Bromo-6-fluoro-4-(2-trimethylsilanyl-ethoxy-
0
0
Jo = 9.0 Hz, ArH3 and H5 ), 7.39 (s, 1H, ArH5), 7.36
(s, 1H, ArH7), 4.90–4.70 (m, 1H, ArNCHCH2), 3.95
(s, 3H, OCH3), 3.95–3.50 (m, 6H, OCH2CH2N and
ArNCHCH2N), 3.46 (br s, 4H, OCH2CH2N), 3.44–
3.18 (m, 2H, ArNCHCH2CH2N), 3.07 (m, 3H,
ArNCH3), 2.77 (m, 3H, CH2NCH3), 2.34-2.22 (m, 2H,
methoxy)-quinoline-2-carboxylic acid methyl ester (10).
A 250 mL, 3-necked round-bottomed flask equipped
with a reflux condenser, nitrogen inlet, and magnetic
stirrer was charged with 9 (1.25 g, 4.17 mmol) and
NMP (75 mL). To this solution was cautiously added
sodium hydride (60% dispersion in oil, 183 mg,
4.58 mmol). Since no reaction occured when the reaction
mixture was cooled in an ice bath, the anion was allowed
to form at room temperature for 1 h. The solution
turned a yellow color when the anion had formed. When
this process was complete, 2-(trimethylsilyl)ethoxymeth-
yl chloride (764 mg, 810 lL, 4.58 mmol) was added to
the reaction. The yellow color then disappeared and
the reaction turned a milky white. This mixture was al-
lowed to stir for an additional 1 h. At the end of this
time, the reaction was cautiously quenched with
100 mL of water and then the entire mixture was poured
into 500 mL of water. The resultant solids were collected
by filtration and washed with water. The solids were
dried and the material further purified by silica gel chro-
matography using 20% ethyl acetate in methylene chlo-
ride as eluent. The pure product was recovered as a
colorless solid (1.4 g, 78%). The structural assignment
of the O alkylation product versus the possible N alkly-
ation was made based upon NMR data. 1H NMR
NCHCH2CH2N);
Mass
Spec.:
Calcd
for
[C27H33N5O4 + H]+ Theor. m/z = 492.2605; Obs. =
492.2603.
4.4. Synthesis of Quinoline 7i
4.4.1. 2-(2-Bromo-4-fluoro-phenylamino)-but-2-enedioic
acid dimethyl ester (8). A 150 mL round-bottomed flask
equipped with a reflux condenser, nitrogen inlet and
magnetic stir bar was charged with 2-bromo-4-fluoroan-
iline (9.85 g, 51.8 mmol). The material was then dis-
solved in methanol (85 mL). To this solution was
added dimethylacetylenedicarboxylate (7.37 g, 6.37 mL,
51.8 mmol). The reaction mixture was heated at reflux
for 18 h. The reaction mixture was cooled to room tem-
perature and then placed in a freezer to allow crystals to
form. The product was isolated as yellow plates by filtra-
tion, followed by washing with cold methanol. The
material was dried in a vacuum oven to yield the prod-
uct as a single diastereomer as determined by NMR
(300 MHz, CDCl3)
d 7.89 (dd, 1H, J = 7.8 Hz,
1
Jm = 3.0 Hz, ArH7), 7.83 (dd, 1H, J = 7.8 Hz,
Jm = 3.0 Hz, ArH5), 7.84 (s, 1H, ArH3), 5.53 (s, 2H,
OCH2O), 4.04 (s, 3H, CO2CH3), 3.82 (t, 2H,
J = 8.3 Hz, OCH2CH2Si), 0.96 (t, 2H, J = 8.3 Hz,
OCH2CH2Si), ꢀ0.03 (s, 9 H, Si(CH3)3); Mass Spec.:
Calcd for [C17H21BrFNO4Si + H]+ Theor. m/z = 430,
432; Obs. = 430, 432.
(14.1 g, 82%). H NMR (300 MHz, CDCl3) d 9.61 (br
s, 1H, NH), 7.33 (dd, 1H, J = 8.0 Hz, Jm = 2.9 Hz,
ArH3), 6.94 (dt, 1H, J = 8.1 Hz, Jm = 2.9 Hz, ArH5),
6.79 (dd, 1H, J = 8.9 Hz, J = 5.3 Hz, ArH6), 5.55 (s,
1H, C@CH), 3.76 (s, 3H, CO2CH3), 3.70 (s, 3H,
CO2CH3); Mass Spec.: Calcd for [C12H11BrFNO4 + H]+
Theor. m/z = 332, 334; Obs. = 332, 334.
4.4.4. 6-Fluoro-8-(4-methyl-piperazin-1-yl)-4-(2-trimeth-
ylsilanylethoxymethoxy)-quinoline-2-carboxylic
4.4.2.
8-Bromo-6-fluoro-4-oxo-1,4-dihydroquinoline-2-
acid
carboxylic acid methyl ester (9). A 500 mL, 3-necked
round-bottomed flask equipped with a reflux condenser,
thermocouple adapter, nitrogen inlet, and magnetic stir-
rer was charged with Dowthermꢀ A (150 mL). The sol-
vent was carefully preheated to 250 ꢁC by applying heat
with a heating mantle. After the solvent reached temper-
ature, 8 (14.1 g, 42.5 mmol) was carefully added as a sol-
id portionwise over 20 min. The mixture was allowed to
react at 250 ꢁC for an additional hour. After cooling to
room temperature, 250 mL of hexane were added. Col-
lection of the resultant solids by filtration, followed by
a hexane wash, yielded 9.9 g (78%) of the pure product.
A second crop (0.85 g) contained not additional pure
product but rather a mixture dominated by the decar-
boxylated side product as identified by LC/MS. 1H
NMR (300 MHz, CDCl3) d 9.34 (br s, 1H, NH), 7.98
(dd, 1H, J = 8.4 Hz, Jm = 2.7 Hz, ArH7), 7.08 (dd, 1H,
J = 7.2 Hz, Jm = 2.7 Hz, ArH5), 6.94 (d, 1H,
J = 1.8 Hz, C@CH), 4.07 (s, 3H, CO2CH3); 13C NMR
(300 MHz, CDCl3) d 178.6, 163.2, 160.6, 157.3, 136.8,
134.0, 128.5, 128.4, 125.7, 125.3, 113.2, 113.1, 111.5,
111.2, 54.2; Mass Spec.: Calcd for [C11H7BrFNO3 + H]+
Theor. m/z = 300, 302; Obs. = 300, 302. Analysis for
methyl ester (11). A 250 mL, 3-necked round-bottomed
flask equipped with a reflux condenser, nitrogen inlet,
and magnetic stirrer was charged with 10 (715 mg,
1.66 mmol), Pd2(dba)3 (30 mg, 0.033 mmol), BINAP
˚
(123 mg, 0.20 mmol), 4 A molecular sieves (1 g), and
anhydrous toluene (100 mL). To the stirred suspension
was then added 1-methylpiperazine (183 mg, 203 lL,
1.82 mmol), followed by cesium carbonate (757 mg,
2.32 mmol). The mixture was heated at 80 ꢁC for 18 h.
The reaction mixture was cooled to room temperature
and filtered through a plug of Celite with toluene wash-
ing to remove solid byproducts. Purification by flash
chromatography using a gradient of 5–20% methanol
in methylene chloride as eluent yielded 560 mg (75%)
1
of the desired product. H NMR (300 MHz, CDCl3) d
7.66 (s, 1H, ArH3), 7.29 (dd, 1H, J = 9.3 Hz,
Jm = 2.7 Hz, ArH7), 6.77 (dd, 1H, J = 11.1 Hz,
Jm = 2.7 Hz, ArH5), 5.41 (s, 2H, OCH2O), 3.90 (s, 3H,
CO2CH3), 3.73 (t, 2H, J = 8.3 Hz, OCH2CH2Si), 3.44
(br s, 4H, ArNCH2CH2N), 2.69 (br s, 4H,
ArNCH2CH2N), 2.33 (s, 3H, NCH3), 0.87 (t, 2H,
J = 8.3 Hz, OCH2CH2Si), ꢀ0.10 (s, 9H, Si(CH3)3); Mass

948
C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
Spec.: Calcd for [C22H32FN3O4Si + H]+ Theor. m/z =
450; Obs. = 450.
room temperature and concentrated in vacuo to afford a
pale yellow solid which was kept under nitrogen and
used as quickly as possible.
4.4.5.
6-Fluoro-8-(4-methyl-piperazin-1-yl)-4-oxo-1,4-
dihydroquinoline-2-carboxylic acid (12). Into a 125 mL
Erlenmeyer flask containing tetrahydrofuran (30 mL)
and methanol (30 mL) was placed 11 (560 mg,
1.24 mmol). To this was added with stirring a solution
of lithium hydroxide monohydrate (104 mg, 2.48 mmol)
in water (30 mL). The reaction mixture was stirred for
1 h and then quenched with 2 N HCl (10 mL). The solu-
tion was filtered and the solids washed with 0.5 N HCl
(10 mL). The combined filtrates were concentrated to
give the solid yellow product as the hydrochloride salt
To a yellow solution of the acid chloride in methylene
chloride (20 mL) were added 4-morpholinoaniline
(0.347 g, 1.94 mmol) and DIEA (1.0 mL, 6.1 mmol).
The solution became orange and gas evolution was ob-
served. Within 30 min, solids began to precipitate from
the solution. The reaction mixture was stirred at room
temperature for 1 h. The solids were isolated by filtra-
tion and dried under high vacuum to afford the desired
product (0.406 g, 49%). 1H NMR (300 MHz, DMSO-d6)
d 10.15 (s, 1H, C(O)NH), 8.33 (s, 1H, ArH3), 8.10 (d,
1H, Jm = 2.7 Hz, ArH7), 7.70 (d, 2H, Jo = 9.0 Hz,
(400 mg,
95%).
Mass
Spec.:
Calcd
for
[C15H16FN3O3 + H]+ Theor. m/z = 306; Obs. = 306.
ArH2 and H6 ), 7.56 (d, 1H, Jm = 2.7 Hz, ArH5), 7.01
0
0
0
0
(d, 2H, Jo = 9.0 Hz, ArH3 and H5 ), 4.06 (s, 3H,
OCH3), 3.75 (t, 4H, J = 4.8 Hz, OCH2CH2N), 3.11 (t,
4H, J = 4.8 Hz, OCH2CH2N); Mass Spec.: Calcd for
[C21H19BrClN3O3 + H]+ Theor. m/z = 476, 478;
Obs. = 476, 478.
4.4.6.
6-Fluoro-8-(4-methyl-piperazin-1-yl)-4-oxo-1,4-
dihydroquinoline-2-carboxylic acid (4-morpholin-4-yl-
phenyl)amide (7i). To a 100 mL round-bottomed flask
equipped with a nitrogen inlet and magnetic stirrer
was added 12 (200 mg, 0.59 mmol). The material was
dissolved in DMF (20 mL) and then treated with 4-mor-
pholinoaniline (125 mg, 0.70 mmol). To the stirred solu-
tion were quickly added simultaneously TBTU (379 mg,
1.18 mmol) and HOBt (160 mg, 1.18 mmol). At this
point DIEA (305 mg, 385 lL, 2.36 mmol) was added
via syringe over 5 min. The reaction mixture was stirred
at room temperature for 18 h and then concentrated on
a rotary evaporator under high vacuum to remove the
DMF. The residue was triturated with methanol and
the crude solids were isolated by filtration. The material
was then dissolved in methylene chloride and extracted
with 10% sodium bicarbonate solution. The organic
layer was dried and concentrated. These residues were
then purified by flash chromatography using a gradient
of 5–10% methanol in methylene chloride as eluent. The
material was then crystallized from methanol to give the
pure product as a yellow solid (150 mg, 55%). 1H NMR
(300 MHz, CDCl3) d 10.28 (s, 1H, CH@CNH), 10.24 (s,
4.5.2. 8-Bromo-4-dimethylamino-6-methoxy-quinoline-2-
carboxylic acid (4-morpholin-4-yl-phenyl)amide (17a). A
solution of 16 (0.1512 g, 0.317 mmol) in 2.0 M dimethyl
amine in THF (100 mL) was heated at 100 ꢁC in a Parr
bomb. The pressure was initially at 75–80 psi and then
remained at approximately 60 psi. After 18 h, the reac-
tion mixture was cooled to room temperature, concen-
trated, and dried to afford the crude product as a
brown solid. Purification on silica gel using a gradient
of 100:0 to 95:5 methylene chloride/methanol afforded
1
the clean product (0.142 g, 92%). H NMR (300 MHz,
DMSO-d6) d 10.20 (s, 1H, C(O)NH), 7.90 (d, 1H,
Jm = 2.7 Hz, ArH5), 7.69 (d, 2H, Jo = 9.0 Hz,
0
0
ArH2 and H6 ), 7.60 (s, 1H, ArH3), 7.41 (d, 1H,
Jm = 2.7 Hz, ArH7), 7.01 (d, 2H, Jo = 9.0 Hz,
0
0
ArH3 and H5 ), 3.96 (s, 3H, OCH3), 3.75 (t, 4H,
J = 4.8 Hz, OCH2CH2N), 3.10 (t, 4H, J = 4.8 Hz,
OCH2CH2N), 3.08 (s, 6H, N(CH3)2); Mass Spec.: Calcd
for [C21H19BrClN3O3 + H]+ Theor. m/z = 485, 487;
Obs. = 485, 487.
0
0
1H, C(O)NH), 7.94 (d, 2H, Jo = 9.0 Hz, ArH2 and H6 ),
7.76 (dd, 1H, J = 8.7 Hz, Jm = 2.6 Hz, ArH7), 7.56 (s,
1H, C@CH), 7.22 (dd, 1H, J = 9.3 Hz, Jm = 2.6 Hz,
0
0
ArH5), 7.01 (d, 2H, Jo = 9.0 Hz, ArH3 and H5 ), 3.90
(t, 4H, J = 4.8 Hz, ArNCH2CH2N), 3.21 (t, 4H,
J = 4.8 Hz, ArNCH2CH2N), 3.08 (br s, 4H,
OCH2CH2N), 2.78 (br s, 4H, OCH2CH2N), 2.45 (br s,
3H, NCH3); Mass Spec.: Calcd for [C25H28FN5O3 + H]+
Theor. m/z = 466.2249; Obs. = 466.2262. Analysis for
C25H28FN5O3Æ0.25HCl: Calculated C, 63.26; H, 6.00;
N, 14.76. Found C, 63.38; H, 5.90; N, 14.70.
4.5.3. 4-Dimethylamino-6-methoxy-8-(4-methyl-pipera-
zin-1-yl)-quinoline-2-carboxylic acid (4-morpholin-4-yl-
phenyl)amide (18a). To a suspension of 17a (139.9 mg,
0.288 mmol), N-methylpiperazine (48 lL, 0.43 mmol),
˚
and 4 A molecular sieves in anhydrous toluene
(15 mL) were added Pd2(dba)3 (15.3 mg, 16.7 lmol),
BINAP (63.0 mg, 0.101 mmol), and cesium carbonate
(0.436 g, 1.345 mmol). The resulting wine colored mix-
ture was heated at reflux under nitrogen for 20 h. The
reaction mixture was cooled to room temperature and
concentrated. The crude mixture was purified by flash
chromatography on silica gel using a gradient of 100:0
to 95:5 methylene chloride/methanol to afford the de-
sired product as a yellow solid (96.9 mg, 67%). 1H
NMR (300 MHz, DMSO-d6) d 10.06 (s, 1H, C(O)NH),
4.5. Synthesis of quinolines 18a–b
4.5.1. 8-Bromo-4-chloro-6-methoxy-quinoline-2-carboxyl-
ic acid (4-morpholin-4-yl-phenyl)amide (16). A suspen-
sion of 3, (0.52 g, 1.75 mmol) in methylene chloride
(20 mL) was treated with oxalyl chloride (1.5 mL,
17.2 mmol) and catalytic DMF (3 drops). The reaction
mixture bubbled vigorously and became clearer. The
reaction was heated at reflux for 2 h. LCMS of a sample
quenched in methanol confirmed complete consumption
of starting material. The reaction mixture was cooled to
0
0
7.69 (d, 2H, Jo = 9.0 Hz, ArH2 and H6 ), 7.58 (s, 1H,
0
0
ArH3), 7.58 (d, 2H, Jo = 9.0 Hz, ArH3 and H5 ), 6.95
(d, 1H, Jm = 2.7 Hz, ArH5), 6.76 (d, 1H, Jm = 2.7 Hz,
ArH7), 3.90 (s, 3H, OCH3), 3.75 (t, 4H, J = 4.8 Hz,
OCH2CH2N), 3.37 (br s, 4H, ArNCH2CH2N), 3.10

C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
949
(t, 4H, J = 4.8 Hz, OCH2CH2N), 3.01 (s, 6H, N(CH3)2),
2.71 (br s, 4H, ArNCH2CH2N), 2.35 (s, 3H,
was poured into water (200 mL) and the resulting solids
were collected by filtration and washed with water to
give the O-methylated product after drying (340 mg,
93%).
ArNCH2CH2NCH3);
Mass
Spec.:
Calcd
for
[C28H36N6O3 + H]+ Theor. m/z = 505.2921; Obs. =
505.2923. Analysis for C28H36N6O3Æ0.05H2O: Calculat-
ed C, 66.53; H, 7.20; N, 16.62. Found C, 66.63; H,
7.06; N, 16.52.
Additional 2D NMR data were used to confirm regiose-
lectivity. HMBC experiments confirmed the proton and
carbon assignments and the presence of proton–carbon
coupling between the methyl protons of the methoxy
group and the C4 of the quinoline ring system which
can only be present with O-alkylation. 1H NMR
4.5.4. 6-Methoxy-4-methylamino-8-(4-methyl-piperazin-
1-yl)-quinoline-2-carboxylic acid (4-morpholin-4-yl-phen-
yl)amide (18b). The title compound was prepared from
16 (0.151 g, 0.31 mmol) according to the method de-
scribed for 18a using N-methyl amine to prepare 8-bro-
mo-4-methylamino-6-methoxy-quinoline-2-carboxylic
acid (4-morpholin-4-yl-phenyl)amide (17b) (pale yellow
solid, 0.131 g, 87%). Following the Buchwald–Hartwig
coupling, the title compound was obtained as a yellow
(300 MHz, CDCl3)
d 7.90 (dd, 1H, J = 7.8 Hz,
Jm = 2.7 Hz, ArH7), 7.84 (dd, 1H, J = 8.9 Hz,
Jm = 2.7 Hz, ArH5), 7.64 (s, 1H, ArH3), 4.14 (s, 3H, Ar-
OCH3), 4.08 (s, 3H, CO2CH3); Mass Spec.: Calcd for
[C12H9BrFNO3 + H]+
Theor.
m/z = 314,
316;
Obs. = 314, 316. Analysis for C12H9BrFNO3: Calculat-
ed C 45.89; H, 2.89; N, 4.46. Found C, 45.64; H, 2.68;
N, 4.52.
1
solid (76.7 mg, 57%). H NMR (300 MHz, DMSO-d6)
d 10.17 (s, 1H, C(O)NH), 7.65 (d, 2H, Jo = 9.0 Hz,
0
0
ArH2 and H6 ), 7.33 (d, 1H, J = 4.7 Hz, ArNH) 7.17
(d, 1H, Jm = 2.1 Hz, ArH7), 7.10 (s, 1H, ArH3),
4.6.2. 6-Fluoro-4-methoxy-8-(4-methyl-piperazin-1-yl)-
quinoline-2-carboxylic acid methyl ester (20). To a
250 mL, 3-necked round-bottomed flask equipped with
a reflux condenser, magnetic stirrer, and nitrogen inlet
were added 19 (2.1 g, 6.68 mmol), Pd2(dba)3 (122 mg,
0
0
7.02 (d, 2H, Jo = 9.0 Hz, ArH3 and H5 ), 6.72
(d, 1H, Jm = 2.1 Hz, ArH5), 3.88 (s, 3H, OCH3),
3.75 (t, 4H, J = 4.8 Hz, OCH2CH2N), 3.31 (br s, 4H,
ArNCH2CH2N, under H2O peak), 3.10 (t, 4H,
J = 4.8 Hz, OCH2CH2N), 2.98 (d, 3H, J = 4.7 Hz,
NHCH3), 2.69 (br s, 4H, ArNCH2CH2N), 2.33 (s,
3H, ArNCH2CH2NCH3); Mass Spec.: Calcd for
[C27H34N6O3 + H]+ Theor. m/z = 491.2765; Obs. =
491.2770. Analysis for C27H34N6O3Æ0.25CH2Cl2Æ0.05-
CH3OH: Calculated C, 63.86; H, 6.81; N, 16.37. Found
C, 64.13; H, 6.56; N, 16.04.
˚
0.134 mmol), BINAP (499 mg, 0.802 mmol), 4 A
molecular sieves (1 g), and anhydrous toluene
(80 mL). To the stirred suspension was added 1-meth-
ylpiperazine (736 mg, 815 lL, 7.35 mmol), followed by
cesium carbonate (3.05 g, 9.35 mmol). The mixture
was heated to 80 ꢁC for 36 h. When the reaction was
determined to be complete, it was cooled to room tem-
perature and filtered through a plug of Celite, with tol-
uene washing to remove solid byproducts. Purification
by flash chromatography, using a gradient of 5–20%
methanol in methylene chloride as eluent, yielded the
desired product (2.0 g, 90%). 1H NMR (300 MHz,
4.6. Synthesis of quinolines 18c
4.6.1. 8-Bromo-6-fluoro-4-methoxy-quinoline-2-carboxyl-
ic acid methyl ester (19). A 150 mL, 3-necked round-bot-
tomed flask equipped with a reflux condenser, magnetic
stirrer, and nitrogen inlet was charged with 9 (2.0 g,
6.76 mmol, 1.0 equiv) in NMP (50 mL). Sodium hydride
(60% dispersion in oil, 300 mg, 7.44 mmol) was cau-
tiously added portionwise to the solution at room tem-
perature. A yellow color developed, indicating that
formation of the anion had occurred, with hydrogen
evolution. Stirring of the anion solution was continued
for 1 h, followed by addition of iodomethane (1.14 g,
500 lL, 8.04 mmol) via syringe. The mixture was al-
lowed to react for an additional 2 h and was then cau-
tiously quenched with 20 mL of water. The solids,
which precipitated upon dilution in 1 L of water, were
collected by filtration, washed with water, and dried to
give the pure O-methylated material as of a colorless sol-
id (2.1 g, 98%).
CDCl3)
d 7.55 (s, 1H, ArH3), 7.37 (dd, 1H,
J = 9.0 Hz, Jm = 2.7 Hz, ArH7), 6.87 (dd, 1H,
J = 11.0 Hz, Jm = 2.7 Hz, ArH5), 4.12 (s, 3H, Ar-
OCH3), 4.09 (s, 3H, CO2CH3), 3.53 (br s, 4H,
ArNCH2CH2N),
2.78
(t,
4H,
J = 4.7 Hz,
ArNCH2CH2N), 2.42 (s, 3H, NCH3); 13C NMR
(300 MHz, CDCl3) d 166.2, 163.7, 163.2, 160.4, 152.6,
152.4, 145.2 (2 peaks), 139.6, 124.5, 124.3, 107.0,
106.6, 100.3, 98.2, 97.9, 56.1, 55.0, 52.8, 51.9, 46.2;
Mass Spec.: Calcd for [C17H20FN3O3 + H]+ Theor. m/z =
334; Obs. = 334.
4.6.3. 6-Fluoro-4-methoxy-8-(4-methyl-piperazin-1-yl)-
quinoline-2-carboxylic acid (21). To a 125 mL Erlenmey-
er flask containing THF (30 mL) and methanol (30 mL)
was added 20 (2.1 g, 6.3 mmol). To this solution was
added with stirring a solution of lithium hydroxide
monohydrate (291 mg, 6.9 mmol) in water (30 mL). This
solution was allowed to react for 1 h and then quenched
with 2 N HCl (10 mL). The solution was then filtered
and the solids washed with 0.5 N HCl (10 mL). The
combined filtrates were concentrated to give the solid
yellow product as the hydrochloride salt (2.15 g, 95%).
Mass Spec.: Calcd for [C16H18FN3O3 + H]+ Theor. m/z =
320; Obs. = 320.
Alternatively, a 100 mL, 3-necked round-bottomed flask
equipped with a reflux condenser, nitrogen inlet, and
magnetic stirrer was charged with 9 (350 mg, 1.17 mmol)
and K2CO3 (242 mg, 1.75 mmol). This material was sus-
pended in DMSO (20 mL) and then heated to 70 ꢁC for
1 h. Formation of the anion was apparent when the mix-
ture became cloudy. The mixture was cooled to 35 ꢁC.
Methyl iodide (331 mg, 145 lL, 2.33 mmol, 2.0 equiv)
was added and stirring continued for 2 h. The mixture

950
C. L. Horchler et al. / Bioorg. Med. Chem. 15 (2007) 939–950
F.; Barr, C. L.; Schachar, R.; Roberts, W.; Malone, M.;
Tannock, R.; Basile, V. S.; Beitchman, J.; Kennedy, J. L.
Mol. Psychiatry 2003, 8, 98–102; (d) Smoller, J. W.;
Biederman, J.; Arbeitman, L.; Doyle, A. E.; Fagerness, J.;
Perlis, R. H.; Sklar, P.; Faraone, S. V. Biol. Psychiatry
2006, 59, 460–467.
4.6.4. 6-Fluoro-4-methoxy-8-(4-methyl-piperazin-1-yl)-
quinoline-2-carboxylic acid (4-morpholin-4-yl-phenyl)am-
ide (18c). To a 250 mL, round-bottomed flask equipped
with a nitrogen inlet and magnetic stirrer was added 21
(2.01 g, 6.3 mmol). The material was dissolved in DMF
(20 mL) and then 4-morpholinoaniline (1.35 g,
7.56 mmol) was added. To the stirred solution were
quickly added simultaneously TBTU (4.05 g,
12.6 mmol) and HOBt (1.7 g, 12.6 mmol). At this point,
DIEA (3.25 g, 4.11 mL, 25.2 mmol) was added via syr-
inge over 5 min. The reaction mixture was allowed to
stir at room temperature for 18 h. The DMF was re-
moved by concentration on a rotary evaporator under
high vacuum. The residue was triturated with methanol
and the crude solids were isolated by filtration. The
material was then dissolved in methylene chloride and
extracted with 10% sodium bicarbonate solution. The
organic layer was dried over MgSO4, filtered, and con-
centrated. The residues were purified by flash chroma-
tography using a gradient of 5–10% methanol in
methylene chloride as eluent. The obtained material
was crystallized from methanol to give the pure product
4. (a) Briley, M.; Moret, C. Clin. Neuropharmacology 1993,
16, 387–400; (b) Chenu, F.; Dailly, E.; Bourin, M. Drug
Dev. Res. 2005, 65, 141–146; (c) Mitchell, S. N.; Greens-
lade, R. G.; Cooper, J. Eur. J. Pharmacol. 2001, 432, 19–
27.
5. (a) Berg, S.; Larsson, L.-G.; Renyi, L.; Ross, S. B.;
Thorberg, S.-O.; Thorell-Svantesson, G. J. Med. Chem.
1998, 41, 1934–1942; (b) Selkirk, J. V.; Scott, C.; Ho,
M.; Burton, M. J.; Watson, J.; Gaster, L. M.; Collin,
L.; Jones, B. J.; Middlemiss, D. N.; Price, G. W. Br. J.
Pharmacol. 1998, 125, 202–208; (c) Jorand-Lebrun, C.;
Pauwels, P. J.; Palmier, C.; Moret, C.; Chopin, P.;
Perez, M.; Marien, M.; Halazy, S. J. Med. Chem. 1997,
40, 3974–3978; (d) Gaster, L. M.; Blaney, F. E.;
Davies, S.; Duckworth, D. M.; Ham, P.; Jenkins, S.;
Jennings, A.; Joiner, G.; King, F.; Mulholland, K.;
Wyman, P.; Hagan, J.; Hatcher, J.; Jones, B.; Middle-
miss, D.; Price, G.; Riley, G.; Roberts, C.; Routledge,
C.; Selkirk, J.; Slade, P. J. Med. Chem. 1998, 41, 1218–
1235.
6. (a) Hudzik, T. J.; Yanek, M.; Porrey, T.; Evenden, J.;
Paronis, C.; Mastrangelo, M.; Ryan, C.; Ross, S.; Stenf-
ors, C. J. Pharmacol. Exp. Ther. 2003, 304, 1072–1084; (b)
Dawson, L. A.; Hughes, Z. A.; Starr, K. R.; Storey, J. D.;
Bettelini, L.; Bacchi, F.; Arban, R.; Poffe, A.; Melotto, S.;
Hagan, J. J.; Price, G. W. Neuropharmacology 2006, 50,
975–983.
7. (a) Ahlgren, C.; Eriksson, A.; Tellefors, P.; Ross, S. B.;
Stenfors, C.; Malmberg, A. Eur. J. Pharmacol. 2004, 499,
67–75; (b) Stenfors, C.; Hallerback, T.; Larsson, L.-G.;
Wallsten, C.; Ross, S. B. Naunyn-Schmiedeberg’s Arch.
Pharmacol. 2004, 369, 330–337.
8. Tidwell, T. H.; Buchwald, S. L. J. Am. Chem. Soc. 1994,
116, 11797–11810.
9. Heindel, N. D.; Bechara, I. S.; Lemke, T. F.; Fish, V. B.
J. Org. Chem. 1967, 4155–4157.
1
as a yellow solid (2.83 g, 93%). H NMR (300 MHz,
CDCl3) d 10.05 (s, 1H, C(O)NH), 7.77 (s, 1H, ArH3),
7.71
(dd,
2H,
Jo = 7.0 Hz,
Jm = 2.0 Hz,
0
0
ArH2 and H6 ), 7.45 (dd, 1H, J = 9.3 Hz, Jm = 2.7 Hz
0
0
ArH7), 6.99 (d, 2H, Jo = 7.0 Hz, ArH3 and H5 ), 6.94
(dd, 1H, J = 10.8 Hz, Jm = 2.7 Hz, ArH5), 4.13 (s, 3H,
ArOCH3), 3.88 (t, 4H, J = 4.8 Hz, OCH2CH2N), 3.51
(br s, 4H, ArNCH2CH2N), 3.17 (t, 4H, J = 4.8 Hz,
OCH2CH2N), 2.83 (t, 4H, J = 4.7 Hz, ArNCH2CH2N),
2.47 (s, 3H, NCH3); 13C NMR (300 MHz, CDCl3) d
164.0, 163.9, 163.1, 161.9, 159.8, 151.5, 151.4, 148.2,
148.1, 138.6, 130.8, 124.3, 124.1, 120.5, 116.5, 107.9,
107.5, 99.2, 98.9, 98.2, 66.9, 56.3, 55.4, 52.1, 49.8, 46.3;
Mass Spec.: Calcd for [C26H30FN5O3 + H]+ Theor.
m/z = 480.2405;
Obs. = 480.2419.
Analysis
for
C26H30FN5O3Æ0.45HCl: Calculated C, 62.97; H, 6.19;
N, 14.12. Found C, 63.24; H, 5.88; N, 14.20.
10. (a) Hartwig, J. F. Angew. Chem. Int. Ed. 1998, 37, 2046–
2067; (b) Wolfe, J. P.; Buchwald, S. L. J. Org. Chem. 2000,
65, 1144–1157.
´
11. De la Cruz, A.; Elguero, J.; Goya, P.; Martınez, A.
Tetrahedron 1992, 48, 6135–6150.
Acknowledgments
12. Glennon, R. A.; Westkaemper, R. B. Drug News &
Perspect. 1993, 6, 390–405.
13. Chapdelaine, M.; Davenport, T.; Haeberlein, M.; Horch-
ler, C.; McCauley, J.; Pierson, Ed.; Sohn, D.; WO
2003037872 A1, 2003.
The authors gratefully acknowledge the contributions of
Drs. M. Edward Pierson, Robert T. Jacobs, and Timo-
thy J. Blake.
14. Lazareno, S. In Methods in Molecular Biology; Walker, J.
M., Keen, M., Eds.; Humana Press: Totowa, New Jersey,
1999; pp 231–245, Vol. 106.
References and notes
1. (a) Childers, W. E., Jr.; Robichaud, A. J. Annu. Rep. Med.
Chem. 2005, 40, 17–33; (b) Robichaud, A. J.; Largent, B.
L. Annu. Rep. Med. Chem. 2000, 35, 11–20, Chap. 2; (c)
Roth, B. L.; Chuang, D.-M. Life Sci. 1987, 41, 1051–1064.
2. (a) Barnes, N. M.; Sharp, T. Neuropharmacology 1999, 38,
1083–1152; (b) Blier, P.; de Montigny, C. Trends Phar-
macol. Sci. 1994, 15, 220–226.
3. (a) Halazy, S.; Lamothe, M.; Jorand-Lebrun, C. Exp.
Opin. Ther. Patents 1997, 7, 339–352; (b) Huang, Y.;
Oquendo, M. A.; Harkavy Friedman, J. M.; Greenhill, L.
L.; Brodsky, B.; Malone, K. M.; Khait, V.; Mann, J. J.
Neuropsychopharmacology 2003, 28, 163–169; (c) Quist, J.
15. Hagan, J. J.; Slade, P. D.; Gaster, L.; Jeffrey, P.; Hatcher,
J. P.; Middlemiss, D. N. Eur. J. Pharmacol. 1997, 331,
169–174.
16. Polar surface areas were calculated according to Ertl, P.;
Rohde, B.; Selzer, P. J. Med. Chem. 2000, 43, 3714–
3717, Calculated PSA values were as follows: 7a–h
2
2
2
2
˚
˚
˚
˚
˚
86.4 A , 7i 77.2 A , 10a 73.4 A , 10b 82.2 A , 10c
2
64.2 A ..
17. Girault, G.; Coustal, S.; Rumpf, P. Bull. Soc. Chim. Fr.
1972, 7, 2787–2798.
18. Berthelot, M.; Laurence, C.; Safar, M.; Besseau, F.
J. Chem. Soc. Perkin Trans. 2 1998, 283–290.