Synthesis, potency, and in vivo evaluation of 2-piperazin-1-ylquinoline analogues as dual serotonin reuptake inhibitors and serotonin 5-HT1A receptor antagonists

Article abstract of DOI:10.1021/jm900374r

On the basis of the previously reported clinical candidate, SSA-426 (1), a series of related 2-piperazin-1-ylquinoline derivatives 3-16 were synthesized and evaluated as dual-acting serotonin (5-HT) reuptake inhibitors and 5-HT _1A receptor anta

Full text of DOI:10.1021/jm900374r

J. Med. Chem. 2009, 52, 4955–4959 4955
DOI: 10.1021/jm900374r
Synthesis, Potency, and in Vivo Evaluation of 2-Piperazin-1-ylquinoline Analogues as Dual Serotonin
Reuptake Inhibitors and Serotonin 5-HT1A Receptor Antagonists
Dahui Zhou,*,† Gary P. Stack,† Jennifer Lo,† Amedeo A. Failli,† Deborah A. Evrard,† Boyd L. Harrison,†
Nicole T. Hatzenbuhler,† Megan Tran,† Susan Croce,† Soo Yi,† Jeannette Golembieski,‡ Geoffrey A. Hornby,‡ Margaret Lai,‡
Qian Lin,‡ Lee E. Schechter,‡ Deborah L. Smith,‡ Adam D. Shilling,§ Christine Huselton,§ Paul Mitchell, Chad E. Beyer,‡ and
Terrance H. Andree‡
†Chemical Sciences, Wyeth Research, CN 8000, Princeton, New Jersey 08543, ‡Discovery Neurosciences, Wyeth Research, CN 8000, Princeton,
New Jersey 08543, §Drug Safety & Metabolism, Wyeth Research, 500 Arcola Road, Collegeville, Pennsylvania 19426, and
Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
Received March 25, 2009
On the basis of the previously reported clinical candidate, SSA-426 (1), a series of related 2-piperazin-
1-ylquinoline derivatives 3-16 were synthesized and evaluated as dual-acting serotonin (5-HT) reuptake
inhibitors and 5-HT1A receptor antagonists. In particular, compound 7 exhibits potent functional
activities at both the 5-HT transporter and 5-HT1A receptor, good selectivity over the R1-adrenergic
and dopaminergic receptors, acceptable pharmacokinetic properties, and a favorable in vivo profile.
Introduction
phores.9 In one of our initial efforts, we incorporated 6-nitroqui-
pazine10 (2, Figure 1) as the 5-HT transporter moiety. The
resulting compound 3 demonstrated good binding affinity for
both the 5-HT transporter and the 5-HT1A receptor. We then
turned our attention to modification of the substitutent at the C6-
position of the quipazine moiety, and of the “linker” (B region,
Figure 1) between the 8-methyl-2,3-dihydro-[1,4]dioxino[2,3-f]
quinolin-2-yl and 2-quinolinyl core. Herein, we report the synth-
esis and in vitro biological evaluation of compounds 3-16, as
well as in vivo characterization of compound 7.
Selective serotonin reuptake inhibitors (SSRIsa) have
achieved great success in treating depression and related
psychiatric illnesses. While SSRIs are efficacious in 60-80%
of patients, they require weeks of treatment before efficacy is
observed.1 This delay in efficacy is believed to be due to
stimulation of inhibitory 5-HT1A autoreceptors, and the onset
of antidepressant activity is consistent with a time-dependent
desensitization of these autoreceptors.2 The combination of
an SSRI and a 5-HT1A receptor antagonist within one mole-
cule could inhibit the 5-HT transporter while simultaneously
antagonizing 5-HT1A autoreceptors to prevent feedback in-
hibition of neuronal firing. This dual mechanism of action
would maximize serotonergic function and result in an im-
mediate increase in synaptic levels of 5-HT in forebrain
regions. Over the past decade, both preclinical and clinical
datahave positioned SSRI/5-HT1A receptorantagonism asan
important target for the development of new antidepressant
therapeutics.3,4 As a result, this approach has been pursued by
many pharmaceutical companies5,6 and has been the focus of
a major effort in our laboratories.7-9
(S)-2-((4-(1H-Indol-3-yl)-5,6-dihydropyridin-1(2H)-yl)-
methyl)-8-methyl-2,3-dihydro-[1,4]dioxino-[2,3-f]quino-
line (SSA-426, 1, Figure 1),7,8 Wyeth’s first advanced SSRI/
5-HT1A antagonist, was tested extensively in preclinical animal
models, lending further support to the potential of this approach
for the treatment of depression. In vivo, this compound produced
an immediate and dose-dependent increase in cortical extracel-
lular levels of 5-HT following oral administration. This com-
pound also showed efficacy in several behavioral models that are
predictive of antidepressant-like activity.8 To further investigate
the SAR and build chemically diverse series of analogues, we
initiated a study to replace the 3-indolyl tetrahydropyridinyl core
(A region, Figure 1) with other 5-HT transporter pharmaco-
Chemistry
The requisite 2-(piperazin-1-yl)quinolines (2, 22-26, and
30-34) and 2-(homopiperazin-1-yl)quinolines (27-28 and
35) were either commercially available (2, 32-35) or were
readily prepared (22-28 and 30-31) by the method outlined
in Schemes 1-2. The 2-(piperazin-1-yl)- and 2-(homopiper-
azine-1-yl)quinoline intermediates 22-28 were prepared by
nucleophilic aromatic substitution of the corresponding 2-
chloroquinolines 17-20 with the piperazines 21a-c or homo-
piperazine21dinN,N-dimethylformamide andinthepresence
of potassium carbonate at 110-140 ꢀC. The construction of 2-
(piperazin-1-yl)quinoline-6-carbonitrile (30) was achieved in
two steps utilizing a nucleophilic aromatic substitution reac-
tion with piperazine-1-carbaldehyde (29). Subsequent heating
of 2-(4-formylpiperazin-1-yl)quinoline-6-carbonitrile in aqu-
eous sulfuric acid (4.0 M) at 130 ꢀC triggered decarbonylation
to give the piperazine analogue 30. 2-(Piperazin-1-yl)quino-
line-6-carboxamide (31) was obtained from the corresponding
cyano analogue 30 via hydrogen peroxide-catalyzed nucleo-
philic addition of sodium hydroxide (Scheme 2). Finally, the
2-(piperazin-1-yl)- and 2-(homopiperazine-1-yl)quinolines
(2, 22-28, and 30-35) underwent N-alkylation under ther-
mal, basic conditions with (R)-(8-methyl-2,3-dihydro-[1,4]
dioxino[2,3-f]quinolin-2-yl)methyl 4-bromo-benzenesulfo-
nate (36)11 to provide the target compounds 3-16 (Scheme 3).
*To whom correspondence should be addressed. Phone: 732-274-
4423. Fax: 732-274-4405. E-mail: zhoud@wyeth.com.
aAbbreviations: SSRIs, selective serotonin reuptake inhibitors; 5-HT,
serotonin; r-5-HT-T, rat serotonin transporter; h-5-HT1A, human 5-
HT1A receptor; CYP450, cytochrome P450.
Results and Discussion
Structure-Activity Relationships. Compounds were eval-
uated in vitro to determine their binding affinities for both
r
2009 American Chemical Society
Published on Web 07/21/2009
pubs.acs.org/jmc

4956 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 15
Zhou et al.
Scheme 2a
a Reagents and conditions: (a) 1-piperazinecarboxaldehyde (29),
DMF, 130 ꢀC; (b) H2SO4, 130 ꢀC; (c) NaOH, 30% H2O2, DMSO.
region with the goal of further increasing the 5-HT trans-
porter binding affinity while retaining the 5-HT1A receptor
binding affinity. The first modification examined the effect
of introducing a methyl group to the C3-position of the
piperazine, using the C6-unsubstituted analogue 10 as a
starting point. As summarized in Table 1, within the pair
of diastereomers 11 and 12, the (R)-methyl piperazinyl
analogue 12 exhibited better binding affinity for the 5-
HT1A receptor than its corresponding (S)-2-methyl isomer
11 but less affinity for the 5-HT transporter. It was our hope
that minor structural changes, such as introduction of the
C6-cyano on the quipazine ring of compound 12, would
afford an increase in binding affinity for the 5-HT transpor-
ter, as suggested by the enhanced binding affinity of the 6-
cyano analogue 7 when compared with C6-unsubstituted
analogue 10. Surprisingly, this goal was not realized: com-
pound 13 demonstrated a 2.7-fold loss in 5-HT transporter
binding affinity when compared to the compound 12.
In the next aspect of the SAR of the linker B region, we
explored the effect of expansion of the piperazine ring to the
homopiperazine. We prepared the C6-unsubstituted analo-
gue 14 first. It is interesting to note that homopiperazine
analogue 14 exhibited nearly equal potencies for both 5-HT
transporter (Ki =7.40 nM) and the 5-HT1A receptor (Ki =
6.79 nM). However, compound 14 showed an increase in 5-
HT1A receptor intrinsic activity (Imax=58%). Introduction
of an electron withdrawing group (fluoro or cyano) at the
C6-position of quipazine ring, exemplified by analogues 15
and 16, provided further improvement in binding affinities at
both 5-HT transporter and 5-HT1A receptor when compared
to compound 14. However, 5-HT1A receptor partial agonist
functions were retained in compounds 15 and 16.
At this stage, we further examined a few compounds
selected from Table 1 for their functional activities at
the human 5-HT transporter site by incubating test com-
pounds with a human carcinoma cell line (JAR cells)
previously treated with staurosporine to enhance the endo-
genous expression of the 5-HT transporter.16 Because SSRIs
can show different affinities at the rat versus human trans-
porter,17 determination of functional activity was done to
confirm activity at human 5-HT transporters. Compound 7
proved to be one of the most potent 5-HT transporter
inhibitors (IC50 = 57.7 ( 14.6 nM vs IC50 = 145 nM for
compound 1 and IC50=39.4 nM for fluoxetine) in this assay.
Considering that the potency for blocking 5-HT1A receptor is
similar (IC50 = 102.1 ( 19.1 nM), this dual mechanism
compound was tested further in microdialysis and the beha-
vioral model.
Figure 1. Compound Design.
Scheme 1a
a Reagents and conditions: (a) piperazine (21a), or (S)-2-methylpi-
perazine (21b) or (R)-2-methylpiperazine (21c) or 1,4-diazepane (21d),
DMF, 110-140 ꢀC.
the serotonin transporter (r-5-HT-T) and the 5-HT1A recep-
tor (h-5-HT1A). Compounds were also evaluated for their
h-5-HT1A receptor functional activity. Antagonism at the 5-
HT1A receptor was determined using a [35S]-GTPγS binding
assay. WAY-100635 (a 5-HT1A receptor antagonist) and
fluoxetine (a 5-HT transporter inhibitor) were used as re-
ference standards (Table 1).
Our SAR study began with an evaluation of the 6-nitroqui-
pazine analogue 3. Compared to 1, compound 3 showed a
9-fold increase in binding affinity for the 5-HT transporter
(Ki = 0.25 nM) but had weaker affinity for the 5-HT1A
receptor (Ki = 20 nM). Encouraged by these results, we
evaluated the effects of other electron-withdrawing substitu-
tents at the C6-position of the 2-(piperazin-1-yl)quinoline ring.
As summarized in Table 1, replacement of the C6-nitro group
on the quipazine moiety with a C6-halogen resulted in substan-
tially decreased binding affinity for the 5-HT transporter but the
binding affinity for the 5-HT1A receptor was maintained. The
exception was the chloro derivative 5, which showed a 10-fold
decrease in binding affinity for the 5-HT1A receptor. Interest-
ingly, the C6-cyano and C6-carboxamide analogues (7 and 8)
demonstrated a 3-5 fold increase in 5-HT1A receptor binding
affinity compared to the corresponding C6-nitro analogue 3.
Replacement of the C6-nitro group with a trifluoromethoxy
group was found to be less favorable; compound 9 exhibited
reduced binding affinities for both the 5-HT transporter and the
5-HT1A receptor. For comparison purposes, the corresponding
C6-unsubstituted analogue 10 was prepared as well. As depicted
in Table 1, compound 10 had only moderate binding affinities
for both the 5-HT transporter and the 5-HT1A receptor.
After optimization of the C6-substitution of compound 3,
we turned our attention toward modification of the linker B
Further selectivity profiling of compound 7 across the R1
adrenergic receptor and the dopamine receptors is depicted
in Table 2. Selectivity of compound 7 for the R1 adrenergic
receptor was determined by incubating rat cortical mem-
branes with [3H]-prazosin.18 Affinity for the dopamine D2,
D3, and D4 receptors was determined using [3H]-spiperone in

Brief Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 15 4957
Scheme 3a
a Reagents and conditions: (a) (R)-(8-methyl-2,3-dihydro-[1,4]dioxino[2,3-f]quinolin-2-yl)methyl 4-bromobenzenesulfonate (36), Et3N or iPr2EtN,
DMSO, 90 ꢀC.
Table 1. 2-Piperazin-1-ylquinoline Derivatives 3-16a
GTPS
R1
n
R2
r-5-HT-T Ki (nM)b
h-5-HT1AKi (nM)c
Imax
%
IC50 (nM)d
fluoxetine
WAY-100635
2.7
0.9
1
3
2.34 ( 0.59
0.25 ( 0.00
66.0 ( 3.5
0.88 ( 0.54
12.7 ( 1.7
13.8 ( 1.0
17.0 ( 0.1
148.5 ( 47.4
75.0 ( 6.2
10.3 ( 4.9
32.8 ( 13.9
89.6 ( 54.3
7.4 ( 2.3
3.02 ( 0.1
20.0 ( 5.2
32.9 ( 0.5
214.1 ( 15.7
17.2 ( 0.5
3.7 ( 0.5
98.3 ( 1.4
79.0 ( 1.4
100 ( 0
62.0 ( 1.4
96.0 ( 0.7
88.6 ( 6.11
100 ( 0
56.7 ( 11.7
294 ( 153
2165 ( 898
781 ( 255
NO2
1
1
1
1
1
1
1
1
1
1
1
2
2
2
H
H
H
H
H
H
H
H
4
F
Cl
5
6
Br
156 ( 8.9
7
CN
CONH2
OCF3
H
102.1 ( 19.7
164.0 ( 10
588.0 ( 24.0
4870 ( 2641
1899 ( 1556
117 ( 14.0
180 ( 23.4
70.0 ( 18.0
58.0 ( 6.4
8
7.2 ( 0.9
9
172.0 ( 30.4
47.3 ( 7.8
167.0 ( 15.6
5.5 ( 1.7
2.8 ( 1.2
6.8 ( 0.3
85.0 ( 1.4
100 ( 0
10
11
12
13
14
15
16
H
(S)-CH3
(R)-CH3
(R)-CH3
H
76.5 ( 19.1
85.0 ( 1.4
92.0 ( 0.2
58.0 ( 2.8
53.0 ( 1.4
74.0 ( 0.7
H
CN
H
CN
F
H
1.1 ( 0.4
3.9 ( 0.1
2.0 ( 0.2
1.5 ( 0.5
H
70.0 ( 19.0
aKI values are the mean of at least two experiments performed in triplicate, determined from nine concentrations and all Ki values were calculated from
IC50 values using the method of Cheng and Prusoff.12 b Binding affinity at rat cortical 5-HT reuptake sites labeled with [3H]-paroxetine.13 cBinding
affinity at human 5-HT1A receptors in CHO cells labeled with [3H]-8-OH-DPAT.14 d Stimulation of GTPγS35 binding in CHO cells expressing the
5-HT1A receptor.15 Imax is the maximum percent inhibition.
CHO cells transfected with human D2, D3, and D4 recep-
tors.19 Gratifyingly, compound 7 displayed high selectivities
against R1 adrenergic receptor and dopamine D2, D3, and D4
receptors. At this point, we have identified a molecule that
met our primary in vitro criteria. We then proceeded to
evaluate this compound in vivo.
Pharmacokinetic Profile. The pharmacokinetic profile of
compound7wasdeterminedinrats.AssummarizedinTable3,
the iv bolus pharmacokinetics of compound 7 exhibited
moderate clearance, volume of distribution and elimination
half-life. Upon oral administration at 3 mg/kg, compound 7
was quickly absorbed, had a moderate terminal half-life, and
good oral bioavailability. However, upon oral dosing at 10 mg/kg,
both the maximum plasma concentration (Cmax) and systemic
exposure (AUC0-¥) increased in a less than dose-proportional
manner, suggesting saturation of absorption.
In Vivo Microdialysis. An in vivo microdialysis assay was
used to investigate the effect compound 7 on 5-HT levels in rat
dorsal lateral frontal cortex, a brain region intimately linked to
impairments in cognition and motor function in depressed
patients.20 Initially, six dialysate samples were taken prior to
drug injection to demonstrate a steady baseline. At the end of
the sixth baseline sample, animals received an oral administra-
tion of compound 7 (3-30 mg/kg, po) or vehicle (2% Tween 80,
po), and dialysis samples were collected for the following 3 h. As
illustrated in Figure 2, acute administration of compound 7

4958 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 15
Zhou et al.
Table 2. Binding Affinities at R1 Adrenergic and Dopaminergic Recep-
tors
r-R1
Ki (nM)
1110
dopaminergic receptors
compd
h-D2Ki (nM)
1306
h-D3 Ki (nM)
h-D4 Ki (nM)
1418
7
1316
Table 3. Pharmacokinetic Profile of 7 in Ratsa
rat PK
1 mg/kg (iv)b 3 mg/kg (oral)c 10 mg/kg (oral)c
C0 (ng/mL)
Cmax (ng/mL)
Tmax (h)
903
456 ( 227
1.3 ( 0.6
815 ( 189
1 ( 0.0
t1/2 (h)
AUC (h ng/mL)
4
3.8 ( 0.3
2320 ( 759
3.8 ( 0.6
4620 ( 1450
1268
13.2
2.5
3
CL (mL/h/kg)
V
Figure 2. Effects of 7 on extracellular 5-HT in frontal cortex.
*Represents overall significant (p<0.05) treatment effect compared
to vehicle group.
ss (mL/kg)
F (%)
61
36
aResults are expressed as mean ( SD of n=3. b Compound dosed
intravenously in 20/80, DMSO/PEG200; n = 2. c Compound dosed
orally in 2% Tween/0.5% methyl cellulose.
(10-30 mg/kg, po) rapidly and dose-dependently elevated
extracellular levels of 5-HT in the rat frontal cortex, an effect
shown to be similar to acute coadministration of fluoxetine and
WAY-100635.21 This effect was not observed with acute fluox-
etine treatment alone.21 At 30 mg/kg, maximal elevations in 5-
HT were 71% above baseline. These results indicated that
combining a serotonin reuptake inhibitor and a 5-HT1A recep-
tor antagonist component within the compound 7 successfully
limited the negative feedback through blockade of the 5-HT1A
autoreceptor and allowed an immediate increase in synaptic
levels of 5-HT, suggesting rapid onset antidepressant effects.
Resident-Intruder Model. The rat resident-intruder model
described by Mitchell and Redfern22 is sensitive to the effects
of antidepressant mechanisms. The acute treatment with a
wide range of antidepressant drugs commonly reduces the
aggressivebehavior22 ofresidentratswhen confrontedwithan
unknown conspecific intruder. In the test, resident animals
were separated 3 days prior to each test day and housed
individually with food and water available ad libitum. Thirty
min prior tothe social encounter, the residentratsweretreated
with either vehicle or compound 7 (3.3, 10.0, and 30 mg/kg,
sc). A drug-free unfamiliar intruder was then introduced into
the resident rats’ home cage and the ensuing social behavior
recorded on to videotape for 10 min.22 As indicated in
Figure 3, compound 7 demonstrated a dose-dependent reduc-
tion in the level of aggressive behavior (ID50=12.5 mg/kg, sc;
F(3,21) =10.642, p =0.0004) at doses that had no effect on
total behavior score (ID50 . 30.0 mg/kg, sc; F(3,21)=0.832,
p=0.4487), consistent with antidepressant-like effects.
Figure 3. Effects of 7 in rat resident-intruder.
ter inhibitor and a 5-HT1A receptor antagonist has been
achieved. The identity of the substituent at the C6-position
of quipazine and the piperazine linker in the B region are
clearly important. Compound 7 from this series was chosen
for further profiling in vitro and in vivo. This compound
dose dependently increased synaptic 5-HT levels after acute
oral administration in a way consistent with a more rapid
antidepressant-like effect. It was also active in the model
predictive of antidepressant activity. Thus, compound 7
represents an important advancement in this area.
Experimental Section
General Procedure: Preparation of Compounds 3-16. A solu-
tion of [(2R)-8-methyl-2,3-dihydro[1,4]dioxino[2,3-f]quinolin-
2-yl]methyl 4-bromobenzenesulfonate11 (36), 2-(1-piperazinyl)
quinoline, and triethylamine (or diisopropylethyl amine) in
dimethyl sulfoxide was heated under nitrogen at 90 ꢀC for
12 h. The reaction was diluted with saturated aqueous sodium
bicarbonate and extracted three times with methylene chloride.
The combined organic layers were washed three times with
water, dried over anhydrous sodium sulfate, filtered, and con-
centrated in vacuo. The residue was purified by chromatogra-
phy on silica gel (1/44/55 methanol/ethyl acetate/hexanes) to
afford the desired product. The material was dissolved in ethyl
acetate and made into its hydrochloride salt using excess ethe-
real hydrochloric acid.
Cytochrome P450 (CYP450) Inhibition. The CYP450 activ-
ities of compound 7 in human liver microsomes were also
evaluated. As a result, compound 7 showed virtually no inhibi-
tion of CYP2A6 or CYP2D6 (tested up to 100 μM concentra-
tion) and only weakly inhibition of CYP2C9 (IC50=358 μM).
Compound 7 moderately inhibited CYP2C8 and CYP2C19
with IC50=29 and 98 μM, respectively. However, compound 7
exhibited potent inhibition of CYP3A4 (IC50=10 μM).
(2S)-8-Methyl-2-{[4-(6-nitroquinolin-2-yl)piperazin-1-yl]-
methyl}-2,3-dihydro[1,4]dioxino[2,3-f ]quinoline (3). Yield: 48%
of an orange foam. The hydrochloride salt was prepared and
collected as a yellow solid; mp 200 ꢀC (dec). 1H NMR (400 MHz,
DMSO-d6). Anal. (C26H25N5O4 2.75HCl) C, H, N.
3
(2S)-2-{[4-(6-Fluoroquinolin-2-yl)piperazin-1-yl]methyl}-8-
methyl-2,3-dihydro[1,4]dioxino[2,3-f ]quinoline (4). Yield: 54%
of a yellow solid; mp 140-141 ꢀC. 1H NMR (400 MHz,
DMSO-d6). Anal. (C26H25FN4O2) C, H, N.
Summary
In this study, we synthesized a class of 2-(piperazin-1-yl)
quinoline analogues 3-16. The goal of creating a single
molecular entity with dual activities as both a 5-HT transpor-
(2S)-2-{[4-(6-Chloroquinolin-2-yl)piperazin-1-yl]methyl}-8-
methyl-2,3-dihydro[1,4]dioxino[2,3-f ]quinoline (5). Yield: 69% of

Brief Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 15 4959
a light-yellow oil. The hydrochloride salt was prepared and col-
transmission in the frontal cortex. J. Psychopharmacol. 2002, 16
(2), 145–152.
(4) Artigas, F.; Perez, V.; Alvarez, E. Pindolol induces a rapid im-
provement of depressed patients treated with serotonin reuptake
inhibitors. Arch. Gen. Psychiatry 1994, 51, 248–251.
(5) Rocco, V. P; Spinazze, P. G.; Kohn, T. J.; Honigschmidt, N. A.;
Nelson, D. L.; Wainscott, D. B.; Ahmad, L. J.; Shaw, J.; Threlkeld,
P. G.; Wong, D. T.; Takeuchi, K. Advances toward new antide-
pressants beyond SSRIs: 1-aryloxy-3-piperidinylpropan-2-ols with
dual 5-HT1A receptor antagonism/SSRI activities. Part 4. Bioorg.
Med. Chem. Lett. 2004, 14, 2653–2656.
(6) Lovell, P. J.; Blaney, F. E.; Goodacre, C. J.; Scott, C. M.; Smith, P.
W.; Starr, K. R.; Thewlis, K. M.; Vong, A. K.; Ward, S. E.;
Watson, J. M. 3,4-Dihydro-2H-benzoxazinones as dual-acting 5-
HT1A receptor antagonists and serotonin reuptake inhibitors.
Bioorg. Med. Chem. Lett. 2007, 17 (4), 1033–1036.
(7) Tran, M.; Stack, G. P. Antidepressant azaheterocyclymethyl deri-
vatives of 2,3-dihydro-1,4-dioxino [2,3-f]quinoline. U.S. patent US
6,458,802, 2002.
(8) Stack, G.; Tran, M.; Harrison, B.; Gross, J.; Husbands, G. E. M.;
Evrard, D. A.; Rosenzweig-Lipson, S.; Dawson, L. A.; Nguyen, H.
Q.; Spangler, T.; Smith, D.; Hornby, G.; Scerni, R.; Gao, H.;
Kalgaonkar, S.; Zhang, G.; Abou-Gharbia, M.; Kim, C.; Schech-
ter, L.; Andree, T. SSA-426: A combined SSRI/5-HT1A antagonist
for the treatment of depression. 233rd ACS National Meeting,
Chicago, IL, March 25-29, 2007; MEDI-233.
(9) Nikitenko, A.; Evrard, D.; Sabb, A. L.; Vogel, R. L.; Stack, Gary;
Young, M.; Lin, M.; Harrison, B. L.; Potoski, J. R. First Scale-Up:
Problems and Resolutions on the Synthesis of WAY-253752, a
Novel, Dual-Acting SSRI/5HT1A Antagonist. Org. Process Res.
Dev. 2008, 12 (1), 76–80.
(10) Vaatstra, W. J.; Deiman-Van Aalst, W. M.; Eigeman, L. DU
24565, a quipazine derivative, a potent selective serotonin uptake
inhibitor. Eur. J. Pharmacol. 1981, 70 (2), 195–202.
1
lected as orange crystals; mp 209-218 ꢀC. H NMR (400 MHz,
DMSO-d6). Anal. (C26H25ClN4O2 2.5H2O 4HCl) C, H, N.
(2S)-2-{[4-(6-Bromoquinolin-2-yl)piperazin-1-yl]methyl}-8-
methyl-2,3-dihydro[1,4]dioxino[2,3-f ]quinoline (6). Yield: 39%
3
3
1
of an off-white solid; mp 153-154 ꢀC. H NMR (400 MHz,
DMSO-d6). Anal. (C26H25BrN4O2) C, H, N.
2-(4-{[(2S)-8-Methyl-2,3-dihydro[1,4]dioxino[2,3-f ]quinolin-
2-yl]methyl}piperazin-1-yl)-quinoline-6-carbonitrile (7). Yield:
72% of a colorless oil. The hydrochloride salt was prepared and
collected as a yellow powder; mp >275 ꢀC. 1H NMR (400 MHz,
DMSO-d6). Anal. (C27H25N5O2 1H2O 2HCl) C, H, N.
3
3
2-(4-{[(2S)-8-Methyl-2,3-dihydro[1,4]dioxino[2,3-f ]quinolin-
2-yl]methyl}piperazin-1-yl)quino-line-6-carboxamide (8). Yield
44% of a colorless oil. The hydrochloride salt was prepared
and collected as a yellow solid; mp 290 ꢀC (dec). 1H NMR (400
MHz, DMSO-d6). Anal. (C27H27N5O3 1H2O 2HCl) C, H, N.
3
3
(2S)-8-Methyl-2-({4-[6-(trifluoromethoxy)quinolin-2-yl]piper-
azin-1-yl}methyl)-2,3-dihydro-[1,4]dioxino[2,3-f ]quinoline (9).
1
Yield: 77% of a yellow solid; mp 174-176 ꢀC. H NMR (400
MHz, DMSO-d6). Anal. (C27H25F3N4O3) C, H, N.
(2S)-8-Methyl-2-[(4-quinolin-2-ylpiperazin-1-yl)methyl]-2,3-
dihydro[1,4]dioxino[2,3-f ]quinoline (10). Yield: 21% of a light-
brown oil. The hydrochloride salt was prepared and collected as
an orange-brown solid; mp 237-243 ꢀC. 1H NMR (400 MHz,
DMSO-d6). Anal. (C26H26FN4O2 1.25H2O 3HCl) C, H, N.
3
3
(2S)-8-Methyl-2-{[(2S)-2-methyl-4-quinolin-2-ylpiperazin-1-
yl]methyl}-2,3-dihydro[1,4]dioxino-[2,3-f ]quinoline (11). Yield:
62% of an off-white solid; mp 141-144 ꢀC. 1H NMR (400 MHz,
DMSO-d6). Anal. (C27H28N4O2 0.2H2O) C, H, N.
(11) Chan, A, W.; Curran, T. T.; Iera, S.; Chew, W.; Sellstedt, J. H.;
Vid, G.; Feigelson, G.; Ding, Z. Process for preparation of
indolylpyridinylmethyldioxinoquinolines and related compounds.
PCT Int. Appl. WO 2002092602, 2002.
3
(2S)-8-Methyl-2-{[(2R)-2-methyl-4-quinolin-2-ylpiperazin-
1-yl]methyl}-2,3-dihydro[1,4]dioxino-[2,3-f]quinoline (12). Yield:
47% of an off-white solid; mp 78-82 ꢀC. 1H NMR (400 MHz,
(12) Cheng, Y.-C.; Preusoff, W. H. Relationship between the inhibition
constant (Ki) and the concentration which causes 50% inhibition (IC50)
of an enzymatic reaction. Biochem. Pharmacol. 1973, 23, 3099–3108.
(13) Cheetham, S. C.; Viggers, J. A.; Slater, N. A.; Heal, D. J.; Buckett,
W. R. [3H]-paroxetine binding in rat frontal cortex strongly corre-
lates with [3H]5-HT Uptake: effect of administration of various
antidepressant treatments. Neuropharmacology 1993, 32, 737–743.
(14) Dunlop, J.; Zhang, Y.; Smith, D. L.; Schechter, L. E. Characteriza-
tion of 5-HT1A receptor functional coupling in cells expressing the
human 5-HT1A receptor as assessed with the Cytosensor microphy-
simeter. J. Pharmacol. Toxicol. Methods 1998, 40, 47–55.
(15) Lazareno, S.; Birdsall, N. J. Pharmacological characterization of
acetylcholilne-stimulated [35S]-GTPγS binding mediated by hu-
man muscarinic M1-M4 receptors: antagonist studies. Br. J.
Pharmacol. 1993, 109, 1120–1127.
(16) Ramamoorthy, J. D.; Ramamoorthy, S.; Papapetropoulos, A.; Ca-
travas, J. D.; Leibach, F. H.; Ganapathy, V. Cyclic AMP-independent
upregulation of the human serotonin transporter by staurosporine in
choriocarcinoma cells. J. Biol. Chem. 1995, 270, 17189–17195.
(17) Barker, E. L.; Kimmel, H. L.; Blakely, R. D. Chimeric human and
rat serotonin transporters reveal domains involved in recognition
of transporter ligands. Mol. Pharmacol. 1994, 46, 799–807.
(18) Morrow, A.; Creese, I. Characterization of R1-adrenergic receptor
subtypes in rat brain: reevaluation of [3H]WB4101 and [3H]prazo-
sin binding. Mol. Pharmacol. 1986, 29, 321–330.
(19) Schechter, L. E.; Smith, D. L.; Rosenzweig-Lipson, S.; Sukoff, S.;
Dawson, L. A.; Marquis, K.; Jones, D.; Piesla, M.; Andree, T.;
Nawoschik, S.; Harder, J. A.; Womack, M. D.; Buccafusco, J.;
Terry, A. V.; Hoebel, B.; Rada, P.; Kelly, M.; Abou-Gharbia, M.;
Barrett, J. E.; Childers, W. Lecozotan (SRA-333): A Selective
Serotonin1A Receptor Antagonist that Enhances the Stimulated
Release of Glutamate and Acetylcholine in the Hippocampus and
Promotes Procognitive Effects. J. Pharmacol. Exp. Ther. 2005, 314
(3), 1274–1289.
(20) Beyer, C. E.; Boikess, S.; Luo, B.; Dawson, L. A. Comparison of
the effects of antidepressants on norepinephrine and serotonin
concentrations in the rat frontal cortex: an in vivo microdialysis
study. J. Psychopharm. 2002, 16, 297–304.
DMSO-d6). Anal. (C27H28N4O2 0.3H2O) C, H, N.
3
2-((3R)-3-Methyl-4-{[(2S)-8-methyl-2,3-dihydro[1,4]dioxino
[2,3-f]quinolin-2-yl]methyl}pipera-zin-1-yl)quinoline-6-carboni-
trile (13). Yield: 67% of a light-yellow foam. 1H NMR (400 MHz,
DMSO-d6). Anal. (C28H27N5O2 0.4H2O) C, H, N.
3
(2S)-8-Methyl-2-[(4-quinolin-2-yl-1,4-diazepan-1-yl)meth-
yl]-2,3-dihydro[1,4]dioxino[2,3-f]-quinoline (14). Yield: 37% of a
yellow foam. 1H NMR (400 MHz, DMSO-d6). Anal. (C27H28-
N4O2 0.5H2O) C, H, N.
2-(4-{[(2S)-8-Methyl-2,3-dihydro[1,4]dioxino[2,3-f ]quinolin-
2-yl]methyl}-1,4-diazepan-1-yl)-quinoline-6-carbonitrile(15). Yield:
3
1
2% of an off-white solid; mp 80-85 ꢀC. H NMR (400 MHz,
DMSO-d6); HRMS (ES) m/z 466.2237 [M + H]+ calcd; m/z
466.2232 [M+H]+ obsd.
(2S)-2-{[4-(6-Fluoroquinolin-2-yl)-1,4-diazepan-1-yl]methyl}-
8-methyl-2,3-dihydro[1,4]dioxino-[2,3-f]quinoline (16). Yield:
50% of a yellow foam; 1H NMR (400 MHz, DMSO-d6). Anal.
(C27H27FN4O2 1.5H2O 2.5HCl) C, H, N.
3
3
Acknowledgment. The authors thank the members of the
Wyeth Chemical Technology Department for their assistance
in the structural confirmation of the compounds described in
this article, and our senior management, Dr. Magid Abou-
Gharbia and the late Dr. Ronald Magolda, from Wyeth
Chemical and Screening Sciences.
Supporting Information Available: Experimental details for
the synthesis of compounds 3-16 and 22-28 and elemental
analysis results for compounds 3-14 and 16. This material is
available free of charge via the Internet at http://pubs.acs.org.
References
(21) Dawson, L. A.; Nguyen, H. Q. Effects of the 5-HT1A receptor
antagonists on fluoxetine-induced changes in serotonin in rat
frontal cortex. Eur. J. Pharmacol. 1998, 345, 41–46.
(22) Mitchell, P. J.; Redfern, P. H. Animal models of depressive illness:
the importance of chronic drug treatment. Curr. Pharm. Des. 2005,
11, 171–203.
(1) Blier, P.; Bergerpm, R. The use of pindolol to potentiate antide-
pressant medication. J. Clin. Psychiatry 1998, 59 (5), 16–23.
(2) Artigas, F.; Adell, A.; Celada, P. Pindolol augmentation of anti-
depressant response. Curr. Drug Targets 2006, 7 (2), 139–147.
(3) Dawson, L. A.; Nguyen, D. L.; Schechter, L. E. Effect of chronic
fluoxetine and WAY-100635 treatment on serotonergic neuro-