Design and Synthesis of trans-3-(2-(4-((3-(3-(5-Methyl-1,2,4-oxadiazolyl))-phenyl)carboxamido) cyclohexyl)ethyl)-7-methylsulfonyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SB-414796): A Potent and Selective Dopamine D3 Receptor Antagonist

Article abstract of DOI:10.1021/jm030817d

At their clinical doses, current antipsychotic agents share the property of both dopamine D₂ and D₃ receptor blockade. However, a major disadvantage of many current medications are the observed extrapyramidal side-effects (EPS), postulated to arise from D₂ receptor antagonism. Consequently, a selective dopamine D₃ receptor antagonist could offer an attractive antipsychotic therapy, devoid of the unwanted EPS. Using SAR information gained in two previously reported series of potent and selective D3 receptor antagonists, as exemplified by the 2,3,4,5-tetrahydro-1H-3-benzazepine 10 and the 2,3-dihydro-1H-isoindoline 11, a range of 7-sulfonyloxy- and 7-sulfonylbenzazepines has been prepared. Compounds of this type combined a high level of D₃ affinity and selectivity vs D₂ with an excellent pharmacokinetic profile in the rat. Subsequent optimization of this series to improve selectivity over a range of receptors and reduce cytochrome P450 inhibitory potential gave trans-3-(2-(4-((3-(3-(5-methyl-1,2,4-oxidiazolyl))phenyl)carboxamido)cyclohexyl) ethyl)-7-methylsulfonyl-2,3,4,5-tetrahydro-1H-3-benzazepine (58, SB-414796). This compound is a potent and selective dopamine D₃ receptor antagonist with high oral bioavailability and is CNS penetrant in the rat. Subsequent evaluation in the rat has shown that 58 preferentially reduces firing of dopaminergic cells in the ventral tegmental area (A10) compared to the substantia nigra (A9), an observation consistent with a prediction for atypical antipsychotic efficacy. In a separate study, 58 has been shown to block expression of the conditioned place preference (CPP) response to cocaine in male rats, suggesting that it may also have a role in the treatment of cue-induced relapse in drug-free cocaine addicts.

Full text of DOI:10.1021/jm030817d

4952
J . Med. Chem. 2003, 46, 4952-4964
Design a n d Syn th esis of tr a n s-3-(2-(4-((3-(3-(5-Meth yl-1,2,4-oxa d ia zolyl))-
p h en yl)ca r boxa m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr a h yd r o-
1H-3-ben za zep in e (SB-414796): A P oten t a n d Selective Dop a m in e D3
Recep tor An ta gon ist
Gregor J . Macdonald,* Clive L. Branch, Michael S. Hadley, Christopher N. J ohnson, David J . Nash,
Alexander B. Smith, Geoffrey Stemp, Kevin M. Thewlis, Antonio K. K. Vong, Nigel E. Austin, Phillip J effrey,
Kim Y. Winborn, Izzy Boyfield, J im J . Hagan, Derek N. Middlemiss, Charlie Reavill, Graham J . Riley,
J eannette M. Watson, Martyn Wood, Steve G. Parker, and Charles R. Ashby J r.†
GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW, UK, and
Department of Pharmaceutical Sciences, College of Pharmacy and Allied Health Professions, Saint J ohn’s University,
J amaica, New York 11439
Received February 20, 2003
At their clinical doses, current antipsychotic agents share the property of both dopamine D2
and D3 receptor blockade. However, a major disadvantage of many current medications are
the observed extrapyramidal side-effects (EPS), postulated to arise from D2 receptor antagonism.
Consequently, a selective dopamine D3 receptor antagonist could offer an attractive antipsychotic
therapy, devoid of the unwanted EPS. Using SAR information gained in two previously reported
series of potent and selective D3 receptor antagonists, as exemplified by the 2,3,4,5-tetrahydro-
1H-3-benzazepine 10 and the 2,3-dihydro-1H-isoindoline 11, a range of 7-sulfonyloxy- and
7-sulfonylbenzazepines has been prepared. Compounds of this type combined a high level of
D3 affinity and selectivity vs D2 with an excellent pharmacokinetic profile in the rat. Subsequent
optimization of this series to improve selectivity over a range of receptors and reduce cytochrome
P450 inhibitory potential gave trans-3-(2-(4-((3-(3-(5-methyl-1,2,4-oxidiazolyl))phenyl)carboxa-
mido)cyclohexyl)ethyl)-7-methylsulfonyl-2,3,4,5-tetrahydro-1H-3-benzazepine (58, SB-414796).
This compound is a potent and selective dopamine D3 receptor antagonist with high oral
bioavailability and is CNS penetrant in the rat. Subsequent evaluation in the rat has shown
that 58 preferentially reduces firing of dopaminergic cells in the ventral tegmental area (A10)
compared to the substantia nigra (A9), an observation consistent with a prediction for atypical
antipsychotic efficacy. In a separate study, 58 has been shown to block expression of the
conditioned place preference (CPP) response to cocaine in male rats, suggesting that it may
also have a role in the treatment of cue-induced relapse in drug-free cocaine addicts.
In tr od u ction
show significant affinity for several serotonin receptors,
a selective dopamine D3 receptor antagonist could
represent an attractive new antipsychotic therapy,
devoid of the unwanted EPS associated with some
currently marketed drugs.5
The emergence and in vivo evaluation of novel,
selective tool compounds has provided new evidence in
support of the attraction of the dopamine D3 receptor
as a target for antipsychotic therapy. We have recently
reported on the novel 6-cyano-1,2,3,4-tetrahydroiso-
quinoline SB-277011 1, a selective dopamine D3 receptor
Dopaminergic neurotransmission is mediated via five
receptor subtypes (D1-D5) which can be further divided
into two families. D1-like receptors encompass the D1
and D5 receptor, while D2-like receptors account for D2,
D3, and D4 subtypes. A number of currently available
antipsychotic drugs, when administered at their clini-
cally effective dose, share the property of both dopamine
D2 and D3 receptor antagonism.1 As a consequence, their
antipsychotic effects could be mediated via D2 and/or
D3 receptors.2 However, a major disadvantage of many
current therapies are the observed extrapyramidal side-
effects (EPS) which are postulated to arise from block-
ade of the D2 receptors in the striatum.3 By contrast,
D3 receptors are highly expressed in limbic regions such
as the nucleus accumbens and antagonism of these
receptors has been associated with beneficial antipsy-
chotic effects.4 Although a number of the recently
marketed antipsychotic agents, such as olanzapine,
antagonist with high oral bioavailability and CNS
penetration in the rat.6 In an in vivo microdialysis study,
we have shown that SB-277011 dose-dependently in-
hibited the quinelorane-induced decrease in dopamine
release from the rat nucleus accumbens at doses of 0.28
to 2.8 mg/kg po, whereas the compound had no effect
* To whom correspondence should be addressed. Gregor J . Mac-
donald, Department of Medicinal Chemistry, H34-3-039, GlaxoSmith-
Kline Pharmaceuticals, New Frontiers Science Park (North), Third
Avenue, Harlow, Essex, CM19 5AW, UK. Tel.: +44 1279627107. Fax:
+44 1279644100. E-mail: Gregor_J _Macdonald@gsk.com.
† Saint J ohn’s University.
10.1021/jm030817d CCC: $25.00 © 2003 American Chemical Society
Published on Web 10/15/2003

New Dopamine D3 Receptor Antagonist
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4953
F igu r e 1. Dopamine D3 receptor antagonists.
in the rat striatum when dosed at 93 mg/kg po.7 In rats,
prolonged treatment with the atypical antipsychotic
clozapine has been reported to preferentially reduce
firing of dopaminergic cells in the ventral tegmental
area (A10) compared to the substantia nigra (A9)sa
phenomenon which has been used to study atypical
antipsychotic agents.8 When SB-277011 was dosed
chronically to adult male rats for 21 days, the compound
was shown to inhibit dopaminergic cell firing in the A10
region but not in the A9 region, with a minimal effective
dose of 1.0 mg/kg po.9 These data further support the
hypothesis that a selective dopamine D3 receptor an-
tagonist may have atypical antipsychotic properties.
There is also considerable evidence to suggest that
dopamine is one of the key neurotransmitters present
in a series of neurological networks known as the
‘reward circuitry’ and plays an important role in the
behaviors related to the reward and reinforcement of
natural and synthetic substances (i.e., drugs of addic-
tion)10,11. Consequently, it has been postulated that
blocking the action of dopamine in the CNS may
represent one way in which to diminish the incentive
value of drugs of addiction. It has previously been
reported that dopamine D2 receptor antagonists such
as haloperidol can diminish the rewarding/reinforcing
effects of various drugs of addiction; however, blockade
of the D2 receptor can produce significant EPS.10 The
presence of the dopamine D3 receptor in projection
regions of the mesocorticolimbic system has also sug-
gested a role in incentive motivation and consequently
a selective dopamine D3 antagonist could find utility in
reinforcement processes and in the treatment of drug
abuse.12 Indeed, studies13,14 with SB-277011 have shown
that it inhibits cocaine-seeking and cocaine-enhanced
brain reward in rats.
Unfortunately, during the early development of
SB-277011, it was shown that while the compound was
stable in the presence of NADPH and liver microsomes
from rat, dog, cynomolgus monkey, and human, in total
liver homogenates from cynomolgus monkey and hu-
man, the intrinsic clearance was 6- and 35-fold higher,
respectively, than in the liver microsomes from these
species. In the absence of NADPH, SB-277011 was also
rapidly cleared in liver homogenates from cynomolgus
monkey and human, demonstrating that a significant
pathway of metabolism was via an NADPH indepen-
dent, nonmicrosomal oxidative route. This pathway was
sensitive to inhibition with isovanillin, suggesting that
the enzyme responsible was aldehyde oxidase.15 The
involvement of aldehyde oxidase in the metabolism of
SB-277011 indicates that the bioavailability in humans
is likely to be low. Interestingly, the resulting metabolite
from this pathway, containing the corresponding 4-sub-
stituted-2-quinolone group, had a much reduced affinity
for the dopamine D3 receptor (pKi 6.5) and only 5-fold
selectivity over the D2 receptor. It has thus been the
aim of our ongoing research program to design a series
of new dopamine D3 antagonists which are highly potent
(pKi g 8) and selective (g100-fold) over a wide range of
other receptors and ion channels, are orally bioavailable
and CNS penetrant, but which are devoid of the liability
to be metabolized by aldehyde oxidase.
Several other antagonists of the D3 receptor have also
been disclosed in the journal and patent literature,
although selectivity against D2 and 5-HT receptors has
varied widely (2-9) (Figure 1).16-23

4954 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Macdonald et al.
In a previous communication, we described the design
and SAR optimization of a novel series of 7-cyano-
substituted 2,3,4,5-tetrahydro-1H-3-benzazepines, as
exemplified by the cinnamide derivative 10, which had
high dopamine D3 affinity (pKi 8.4; Ki 4 nM) and 130-
fold selectivity over the dopamine D2 receptor.24 This
compound also displayed g100-fold selectivity against
a range of other receptors, low potential to inhibit
cytochrome P450, and good systemic exposure in the rat
and was brain penetrant. However, in vitro metabolism
studies with 10 showed a high clearance rate in human
liver microsomes, precluding further development of this
particular compound. To advance the development of
the benzazepine series, suitable alternative templates
were sought as a basis for further SAR investigations.
We had previously shown in a related publication, which
described the design of novel 2,3-dihydro-1H-isoindo-
lines as selective D3 antagonists,25 that the 5-methyl-
sulfonyloxy isoindoline 11 had high D3 receptor affinity
(pKi 8.3), 100-fold selectivity over the D2 receptor and
had a highly desirable pharmacokinetic profile in the
rat, with low blood clearance (14 mL/min/kg), high oral
bioavailability (77%), and long terminal half-life (5.2 h).
Therefore, we sought to explore the introduction of a
sulfonyloxy group into the benzazepine series in an
attempt to improve the overall in vivo properties of these
particular compounds. Herein we now describe the SAR
analysis of a range of 7-sulfonyloxy- and related 7-sul-
fonyl-2,3,4,5-tetrahydro-1H-3-benzazepines which has
provided potent and selective dopamine D3 receptor
antagonists with high oral bioavailability and excellent
in vivo profiles in the rat.
Ch em istr y
Compounds 18-34 (Table 1) were readily prepared
via an extension of our previously reported route
to 7-substituted 2,3,4,5-tetrahydro-1H-3-benzazepines
(Scheme 1). Thus, reaction of 3-tert-butoxycarbonyl-7-
hydroxy-2,3,4,5-tetrahydro-1H-3-benzazepine 1224 with
methanesulfonyl chloride afforded the sulfonate deriva-
tive 13 in 99% yield. Removal of the tert-butoxycarbonyl
group with trifluoroacetic acid followed by reductive
amination with the previously disclosed6 protected
amino aldehyde 15 gave amine 16 in 80% yield. Sub-
sequent deprotection with trifluoroacetic acid provided
the corresponding amine 17, which was coupled with
the requisite acid using 1-(3-dimethylaminopropyl)-3-
ethylcarbodiimide and 1-hydroxybenzotriazole in dichlo-
romethane to give the targeted compounds 18-34.
Compounds 43-58 (Table 2) were prepared by a
similar process, although in this case, the required
7-substituted benzazepine intermediate 40 was derived
from the unsubstituted benzazepine 36 (Scheme 2).26
Thus, o-phenylene diacetonitrile 35 was cyclized in the
presence of Raney nickel and hydrogen in ethanolic
ammonia at high pressure and temperature to afford
Sch em e 1

New Dopamine D3 Receptor Antagonist
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4955
Sch em e 2
2,3,4,5-tetrahydro-1H-3-benzazepine 36 in 60% yield.
This material was then protected and purified as the
N-acetyl derivative 37. Treatment of 37 with chlorosul-
fonic acid in dichloromethane followed by reductive
methylation provided the N-acetyl-7-methylsulfonyl-
2,3,4,5-tetrahydro-1H-3-benzazepine 39 in 33% yield
over two steps.
Removal of the N-acetyl group was carried out using
aqueous hydrochloric acid at reflux to give the 7-meth-
ylsulfonyl-2,3,4,5-tetrahydro-1H-3-benzazepine 40 in
excellent yield. Use of methodology similar to that
outlined in Scheme 1 then afforded the targeted amides
43-58 in good overall yield.
over the D2 receptor while maintaining the high D3
affinity in this series, further analogues were prepared
to explore the SAR around the amide moiety (21-34).
Replacement of the fluoro substituent by an electron-
donating group such as methoxy similarly provided
compounds of high potency 21-23, but this modification
was generally detrimental to the selectivity profile with
respect to D2 receptors. Incorporation of the 1-naphthyl
group, 24, which had previously been examined as a
tetrahydroisoquinoline derivative,6 resulted in a reduc-
tion of D3 affinity (pKi 8.6), but interestingly >100-fold
selectivity against the D2 receptor was observed for the
first time in this series. Further cross-screening, how-
ever, revealed that the selectivity of 24 vs 5-HT1D
receptors was only 15-fold. Replacement of the 1-naph-
thyl group of 24 with the 5-quinolinyl moiety, as
exemplified by 25, maintained both D3 receptor affinity
and 100-fold selectivity vs D2 receptors. Introduction of
a methyl substituent at C-2 of the quinolinyl group
proved beneficial and resulted in a compound with both
excellent affinity and improved selectivity (26; pKi 8.9;
160-fold selective vs D2). By contrast, the 2-Me-4-
quinolinyl group 27 appeared detrimental to both D3
affinity and selectivity in this series (27 vs 26). Com-
pound 26 was therefore selected for further in vitro
profiling against a range of 5-HT receptors and was
shown to have g100-fold selectivity. Additionally, 26
Resu lts a n d Discu ssion
To provide a direct comparison with the previously
prepared isoindoline 11, the corresponding 4-fluorocin-
namide derivative 18 was first prepared in the 7-sul-
fonyloxy benzazepine series (Table 1). Compound 18 had
an excellent dopamine D3 receptor binding affinity (pKi
9.1) and had 80-fold selectivity against the D2 receptor.
Unfortunately, 18 was shown to be an inhibitor of
cytochrome P450 2D6 with an IC50 of 3 uM. The 3-fluoro
and 2-fluoro analogues, 19 and 20 respectively, also
showed high affinity for the D3 receptor; however,
selectivity vs D2 receptors was not improved compared
to 18. In an attempt to achieve the desired selectivity

4956 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Macdonald et al.
Ta ble 1. Affinities (pKi) of 7-Methylsulfonyloxy-2,3,4,5-Tetrahydro-1H-3-Benzazepiness
a
b
pKi values at the human cloned receptors represent the mean of at least three determinations. D3/D2 selectivity is defined as the
antilogarithm of the difference between D3 and D2 pKi values.
had low inhibitory potential against all the P450
enzymes (all IC50 values >40 uM), thus representing a
marked improvement in the overall profile compared to
18.
From subsequent in vivo evaluation, compound 26
was found to have an excellent pharmacokinetic profile
in the rat, with blood clearance of 18 mL/min/kg, an oral
bioavailability of 79%, and half-life of 5.2 h. A steady-
state CNS penetration study showed that 26 had a
brain:blood ratio of 1.3:1.
However, more extensive in vitro cross screening
revealed that 26 had high affinity for muscarinic recep-
tors (M1, M2, and M3), with selectivity being particularly
low against the M2 subtype (10-fold). In an attempt to
overcome this selectivity issue associated with com-
pound 26, a range of more diverse amide modifications
was explored. From this investigation, a series of
3-substituted biaryl carboxamides (28-34) emerged as
promising new leads (see Table 1). The 1,2,4-oxadiazolyl
derivative 28 showed high D3 receptor affinity (pKi 8.6)
and had 80-fold selectivity vs D2 receptors. This com-
pound had greater than 100-fold selectivity against
5-HT receptors, had low intrinsic clearance in mi-
crosomes, and showed no significant inhibition of cyto-
chrome P450 enzymes. In contrast, although the 2-Me-
1,3-oxazol-5-yl 29 showed exceptional D3 affinity and
160-fold selectivity against D2, the P450 profile was
markedly worse than that of compound 28.
A number of other variations of the five-membered
heterocycle 30-32 were explored, but unfortunately,
selectivity against either the D2 receptor or 5-HT
receptors remained an issue. A balance was obtained
with the 5-Me-1,3-oxazol-2-yl derivative 33 which had
high D3 affinity (pKi 8.5), was 100-fold selective against
D2, and had no significant P450 interactions. In addi-
tion, although affinity for the M2 receptor had not been
totally abolished, an improved selectivity of 25-fold was
obtained. A subsequent in vivo study in the rat showed
that 33 was CNS penetrant (brain:blood; 1.1:1) and had
low blood clearance (21 mL/min/kg).
Further SAR investigations showed that a six-
membered heterocyclic biaryl such as the 2-pyrimidinyl

New Dopamine D3 Receptor Antagonist
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4957
Ta ble 2. Affinities (pKi) of 7-Methylsulfonyl-2,3,4,5-Tetrahydro-IH-3-Benzazepines
a
b
pKi values at the human cloned receptors represent the mean of at least three determinations. D3/D2 selectivity is defined as the
antilogarithm of the difference between D3 and D2 pKi values.
group was also well tolerated with respect to D3 affinity
and selectivity. Compound 34, in addition to being
>100-fold selective against all the 5-HT receptors
screened, also showed an improved selectivity of 50-fold
against the M2 receptor.
an IC50 of 7 uM, a recurrent theme with many of the
substituted cinnamide derivatives.
As observed in the previous sulfonyloxy series (25 and
26), the quinolinyl carboxamide group was beneficial for
maintaining high D3 affinity and selectivity. The cor-
responding sulfone 52 also showed good affinity for the
D3 receptor (pKi 8.4), but was only 80-fold selective
against the 5-HT2B receptor. Interestingly, introduction
of an 8-fluoro substituent on the quinolinyl ring 53
significantly improved the selectivity over the 5-HT2B
receptor to 250-fold. Compound 52 had moderate in vivo
clearance (46 mL/min/kg), excellent oral bioavailability
(91%), and was CNS penetrant (brain:blood ratio of 1.2:
1), comparable with the corresponding sulfonyloxy
derivative 26. Unfortunately, 52 had low selectivity
against muscarinic receptors (M1 10-fold; M2 3-fold and
M3 8-fold), paralleling the data generated in the sulfo-
nyloxy series.
The encouraging overall in vitro and in vivo profile
observed with the 7-methylsulfonyloxy benzazepine
series prompted an extension of this program to exam-
ine the key SAR in the related 7-methylsulfonyl benz-
azepine series. Excellent D3 receptor binding affinities
were retained in this series (Table 2), as highlighted for
example by the 4-fluorocinnamide derivative 43 with
pKi 9.0. Interestingly, in contrast to the corresponding
sulfonyloxy derivatives, >100-fold selectivity vs D2
receptors could be achieved with suitably substituted
cinnamides, such as the mono- and difluoro derivatives
45 and 47 with 100 and 160-fold selectivity, respectively.
The 2-fluorocinnamide 45 also showed a very encourag-
ing cross screening profile and had no significant P450
liabilities. Unfortunately, compound 45 showed high
intrinsic clearance in human liver microsomes. Other
substituents such as cyano were also tolerated, with the
C-2 position being marginally preferred for selectivity
against D2 receptors (48-50). However, 2-cyanocinna-
mide 50 was an inhibitor of cytochrome P450 2C9 with
As in the sulfonyloxy series, 3-biaryl carboxamides
provided compounds with the most promising balance
of in vitro properties. Although 54 and 55 showed the
required levels of affinity and selectivity against the
target receptors, both had extensive P450 liabilities. The
5-methyloxazol-2-yl replacement in 56 provided a solu-
tion for the P450 inhibitory potential, unfortunately

4958 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Macdonald et al.
however at the expense of selectivity (<100-fold against
D2, 5-HT2B, 5-HT2C, and 5-HT4 receptors). The isoxazolyl
57 also had high D3 receptor affinity and selectivity over
the D2 receptor; however, selectivity against the M2
receptor was < 10-fold.
produced by the drug alone. Thus, all animals were
administered either vehicle (methylcellulose, 1 mg/kg
ip) or cocaine (15 mg/kg ip) in the appropriate chamber
of the CPP apparatus every other day for 8 days (i.e., 4
vehicle/cocaine pairings). These chambers were designed
to create a specific environment with distinct cues. On
the ninth day, the cocaine treated rats showed a
significant CPP response, similar to that previously
reported.28 Twenty-four hours after the last pairing,
animals were randomly allocated to receive a single po
injection of vehicle or 0.3, 1, 3, or 10 mg/kg of 58, 3.5 h
before being placed back in the CPP apparatus. The po
administration of either 0.3, 1, 3, or 10 mg/kg of 58
produced a significant decrease in the time the animals
spent in the chamber paired to cocaine on the test day.
It can therefore be concluded that compound 58 blocks
the expression of the CPP response to cocaine. Given
that CPP is hypothesized to be a measure of the ability
of neutral environmental cues to elicit approach behav-
ior following pairing with substrates that are considered
to produce incentive motivation, the results of this study
suggest that compound 58 may have a potential use in
the treatment of cue-induced relapse in drug-free co-
caine addicts.
From this SAR investigation, the 5-methyl-1,2,4-
oxadiazol-2-yl derivative 58 represented the most en-
couraging analogue to be prepared. Compound 58 (SB-
414796) retained good affinity for the D3 receptor (pKi
8.4), was 100-fold selective against the D2 receptor and
a panel of 60 other receptors and ion channels, and 30-
fold selective vs muscarinic M2 receptors. An in vitro
functional assay using microphysiometry in CHO cells
expressing the human cloned D3 and D2 receptors27
showed that 58 lacked any agonist activity and was a
potent D3 receptor antagonist (pKb 8.5), with 100-fold
selectivity over the D2 receptor (pKb 6.5). In addition,
compound 58 showed no significant cytochrome P450
liabilities. The pharmacokinetic profile in the rat was
also excellent (plasma clearance 29 mL/min/kg; oral
bioavailability 85%; terminal half-life 3.5 h), and the
compound was CNS penetrant with a brain:blood ratio
of 0.3:1. In addition, as the HCl salt, compound 58 had
an aqueous solubility of >3 mg/mL at pH 7.4.
Further in vivo evaluation was carried out in anes-
thetized male Sprague-Dawley rats to examine the
effect of chronic administration of compound 58 on the
number of spontaneously active dopamine neurons in
the substantia nigra pars compacta (A9) and ventral
tegmental area (A10). Repeated po administration for
21 days of either 0.3, 1, or 3 mg/kg of 58 produced a
significant decrease in the number of spontaneously
active neurons in the A10 region compared to vehicle-
treated animals. In contrast, none of the doses of 58
significantly altered the number of spontaneously active
neurons in the A9 region compared to vehicle-treated
animals. These data are consistent with data previously
obtained with the selective dopamine D3 receptor an-
tagonist SB-277011.
Con clu sion s
Starting from the previously reported 7-cyano-2,3,4,5-
tetrahydro-1H-3-benzazepine 10, two new series of
7-sulfonyl and 7-sulfonyloxy benzazepines have been
designed. Both series have provided compounds with
high affinity and selectivity for the dopamine D3 recep-
tor in addition to a highly desirable pharmacokinetic
profile in the rat. This study has resulted in the
identification of 58 (SB-414796) which is a potent and
selective D3 antagonist with low potential to inhibit
cytochrome P450 enzymes, low blood clearance (29 mL/
min/kg), and high oral bioavailability (85%) and is brain
penetrant (0.3:1) in the rat. Preliminary biological
evaluation in rats suggest that 58 produces a significant
reduction in dopaminergic cell firing in the ventral
tegmental (A10) but not in the substantia nigra (A9)
brain region compared to vehicle-treated animals. This
suggests that as a selective D3 receptor antagonist, 58
may have the properties of an atypical antipsychotic
agent. Initial data showing that 58 can block the
expression of the conditioned place preference response
to cocaine in male rats may also support the hypothesis
that a selective D3 antagonist could be a potential
treatment for cue-induced relapse in drug addicts. In
can therefore be concluded that compound 58 represents
a novel and exciting pharmacological tool for the further
understanding of the biological significance of dopamine
D3 receptors in the CNS.
Data from established catalepsy and prolactin models
suggest that a selective dopamine D3 antagonist would
have reduced liability to induce the EPS and hyperpro-
lactinaemia associated with conventional antipsychotic
agents. In agreement with this, compound 58 showed
no cataleptic activity at doses up to 100 mg/kg po, and
although levels of prolactin were increased at 30 and
100 mg/kg, these were not statistically significant. In
these models, the typical antipsychotic compound halo-
peridol produced a complete cataleptic response and
increased prolactin levels at doses of 3 mg/kg po.
A study was also conducted to determine the effects
of 58 on the expression of cocaine-induced condition
place preference (CPP) in male Sprague-Dawley rats.
In the CPP paradigm, the primary motivational proper-
ties of a drug, defined as an unconditioned stimulus
(UCS), is repeatedly paired with a previously neutral
set of environmental stimuli. During a course of condi-
tioning, these environmental stimuli can acquire sec-
ondary motivational properties and thus act as condi-
tioned stimuli (CS) that can elicit approach when the
animal is reexposed to the conditioned stimuli. The CPP
paradigm also indicates that neutral stimuli associated
with the pharmacological effects of psychoactive drugs
eventually induce physiological states similar to those
Exp er im en ta l Section
Ch em istr y. Melting points were determined on a Buchi
melting point apparatus and are uncorrected. 1H NMR spectra
were recorded on a Bruker AMX 400, a J EOL GX 270, or a
Bruker AC 250. High-resolution mass spectra were recorded
using a Micromass Q-Tof 2 electrospray mass spectrometer.
Low-resolution mass spectra were recorded using a Fisons VG
Platform. LC-mass spectra (LCMS) were recorded using a
Hewlett-Packard HP 1100 System attached to a Waters
Micromass ZMD electrospray ionization mass spectrometer.
A SORBAX SB C18 3.5 µm (30 × 2.1 mm) column was used
with elution using the following conditions: eluent A, 0.1%

New Dopamine D3 Receptor Antagonist
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4959
TFA/H2O v/v, eluent B, 0.1% TFA/CH3CN v/v; flow rate, 0.75
mL/min. The elution gradient was 5-95% B increased over
1.5 min and then held for 0.5 min A detection wavelength of
215 nm was used. Merck Kieselgel 60 was used for column
chromatography. All solvent evaporation was performed under
vacuum.
Hz), 2.55-2.65 (5 H, m), 2.88-2.95 (4H, m), 3.12 (3H, s), 7.00-
7.02 (2H, m), 7.11 (1H, d, J ) 8 Hz). Mass spectrum (API+):
Found 367 (MH+). C19H30N2O3S requires 366.
tr a n s-3-(2-(4-((5-(2-Met h ylq u in olin yl))ca r b oxa m id o)-
cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tetr ah ydr o-
1H-3-ben za zep in e (26). A mixture of trans-3-(2-(4-aminocy-
clohexyl)ethyl)-7-methylsulfonyloxy-2,3,4,5-tetrahydro-1H-3-
benzazepine 17 (150 mg, 0.41 mmol), 2-methylquinoline-5-
carboxylic acid (92 mg, 0.49 mmol), 1-ethyl-3-(3-dimethylamino
propyl)carbodiimide hydrochloride (86 mg, 0.45 mmol), and
1-hydroxybenzotriazole (5 mg) in dichloromethane (10 mL) was
shaken at room temperature for 18 h. A saturated solution of
sodium bicarbonate (4 mL) was then added and the mixture
shaken for a further 0.25 h. The organic phase was then
applied directly to a silica gel column and eluted with a
gradient of 30-100% ethyl acetate in hexane followed by
0-10% methanol in ethyl acetate to give 26 (161 mg, 74%) as
a colorless solid. 1H NMR (CDCl3) δ: 1.10-1.30 (5H, m), 1.45-
1.50 (2H, m), 1.80-1.90 (2H, m), 2.15-2.20 (2H, m), 2.50-
2.55 (2H, m), 2.60-2.70 (4H, m), 2.73 (3H, s), 2.90-3.00 (4H,
m), 3.13 (3H, s), 4.00-4.15 (1H, m), 5.92 (1H, d, J ) 8 Hz),
6.95-7.15 (3H, m), 7.30 (1H, br s), 7.50-7.55 (1H, m), 7.70-
7.75 (1H, m), 8.00-8.15 (2H, d). Mass Spectrum (API+): Found
536 (MH+). C30H37N3O4S requires 535. The purity was deter-
mined as >98% by LC-MS, retention time 0.68 min.
3-(ter t-Bu t oxyca r b on yl)-7-m et h ylsu lfon yloxy-2,3,4,5-
tetr a h yd r o-1H-3-ben za zep in e (13). A solution of 3-(tert-
butoxycarbonyl)-7-hydroxy-2,3,4,5-tetrahydro-1H-3-benzaze-
pine 1219 (3.00 g, 0.011 mol), methanesulfonyl chloride (1.44
g, 0.013 mol), triethylamine (1.27 g, 0.013 mol), and dichlo-
romethane (50 mL) was stirred at room temperature for 18 h.
The reaction mixture was then partitioned between dichlo-
romethane (50 mL) and a saturated solution of sodium
hydrogen carbonate (50 mL). The organic layer was separated,
washed with water (50 mL), and then dried (Na2SO4). The
solvent was then evaporated in vacuo to give 13 (3.85 g, 99%)
as a pale yellow oil. 1H NMR (CDCl3) δ: 1.48 (9H, s), 2.85-
2.92 (4H, m), 3.13 (3H, s), 3.53-3.56 (4H, m), 7.00-7.03 (2H,
m), 7.13-7.16 (1H, m). Mass spectrum (API+): Found 242 (M
- Boc)H+. C16H23NO5S requires 341.
7-Met h ylsu lfon yloxy-2,3,4,5-t et r a h yd r o-1H -3-b en za -
zep in e (14). A solution of 3-(tert-butoxycarbonyl)-7-methyl-
sulfonyloxy-2,3,4,5-tetrahydro-1H-3-benzazepine 13 (3.8 g,
0.011 mol), trifluoroacetic acid (3.76 g, 0.033 mol), and dichlo-
romethane (50 mL) was heated at 50 °C for 5 h. The solvents
were then evaporated in vacuo, and the residue was parti-
tioned between water (200 mL) and ethyl acetate (150 mL).
The aqueous layer was washed with ethyl acetate (100 mL)
and then basified (pH ) 14) with a 40% solution of sodium
hydroxide. The suspension was then extracted with ethyl
acetate (3 × 150 mL), and the combined organic layers were
then dried (Na2SO4). The solvent was then evaporated in vacuo
The following compounds were prepared in a manner similar
to compound 26.
tr a n s-3-(2-(4-((3-(4-F lu or op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (18). 1H NMR (CDCl3) δ: 1.05-
1.35 (5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m), 2.00-
2.10 (2H, m), 2.50-2.60 (2H, m), 2.60-2.75 (4H, m), 2.90-
3.00 (4H, m), 3.13 (3H, s), 3.80-3.90 (1H, m), 5.38 (1H, d, J )
8 Hz), 6.26 (1H, d, J ) 16 Hz), 7.00-7.15 (5H, m), 7.45-7.50
(2H, m), 7.56 (1H, d, J ) 16 Hz). Mass Spectrum (API+):
Found 515 (MH+). C28H35FN2O4S requires 514. The purity was
determined as >98% by LC-MS, retention time 0.87 min.
tr a n s-3-(2-(4-((3-(3-F lu or op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (19). 1H NMR (CDCl3) δ: 1.05-
1.30 (5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m), 2.00-
2.10 (2H, m), 2.45-2.55 (2H, m), 2.55-2.65 (4H, m), 2.85-
2.95 (4H, m), 3.13 (3H, s), 3.80-3.90 (1H, m), 5.42 (1H, d, J )
8 Hz), 6.33 (1H, d, J ) 16 Hz), 6.95-7.35 (7H, m), 7.56 (1H, d,
1
to give 14 (2.42 g, 90%) as a colorless oil. H NMR (CDCl3) δ:
2.88-3.00 (8H, m), 3.13 (3H, s), 7.00-7.05 (2H, m), 7.12 (1H,
d). Mass spectrum (API+): Found 242 (MH+). C11H15NO3S
requires 241.
tr a n s-3-(2-(4-(N-ter t-Bu toxycar bon ylam in o)cycloh exyl)-
eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tetr a h yd r o-1H-3-ben z-
a zep in e (16). A mixture of 7-(methylsulfonyloxy)-2,3,4,5-
tetrahydro-1H-3-benzazepine 14 (2.00 g, 8.30 mmol) and trans-
2-(1-(4-N-tert-butoxycarbonyl)amino)cyclohexyl acetaldehyde
156 (2.00 g, 8.30 mmol) in dichloroethane (30 mL) was stirred
at room temperature for 5 min before sodium triacetoxyboro-
hydride (1.85 g, 8.72 mmol) was added in a single portion. After
the mixture was stirred at room temperature for 48 h, a
saturated solution of sodium hydrogen carbonate (50 mL) was
added and the two layers separated. The aqueous layer was
extracted with dichloromethane (3 × 60 mL), and the combined
organic layers were dried (Na2SO4). The solvent was then
evaporated in vacuo and the residue purified by column
chromatography (silica gel, ethyl acetate) to give 16 (3.10 g,
J ) 16 Hz). Mass Spectrum (API+): Found 515 (MH+). C28H35
FN2O4S requires 514.
-
tr a n s-3-(2-(4-((3-(2-F lu or op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (20). 1H NMR (CDCl3) δ: 1.05-
1.30 (5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m), 2.00-
2.10 (2H, m), 2.45-2.55 (2H, m), 2.55-2.65 (4H, m), 2.85-
2.95 (4H, m), 3.13 (3H, s), 3.80-3.90 (1H, m), 5.44 (1H, d, J )
8 Hz), 6.49 (1H, d, J ) 16 Hz), 6.95-7.05 (2H, m), 7.05-7.15
(3H, m), 7.25-7.35 (1H, m), 7.40-7.50 (1H, m), 7.65 (1H, d, J
1
80%) as a white solid. H NMR (CDCl3) δ: 0.9-1.25 (7H, m),
1.44 (9H, s), 1.70-1.80 (2H, m), 1.90-2.05 (2H, m), 2.40-2.50
(2H, m), 2.55-2.65 (4H, m), 2.88-2.95 (4H, m), 3.12 (3H, s),
3.36 (1H, br s), 4.34 (1H, br s), 6.98-7.02 (2H, m), 7.08-7.12
(1H, d). Mass spectrum (API+): Found 467 (MH+). C24H38N2O5S
requires 466.
) 16 Hz). Mass Spectrum (API+): Found 515 (MH+). C28H35
-
FN2O4S requires 514. The purity was determined as >98% by
LC-MS, retention time 0.86 min.
tr a n s-3-(2-(4-((3-(4-Met h oxyp h en yl)p r op -2-en yl)ca r -
boxa m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-
tetr a h yd r o-1H-3-ben za zep in e (21). 1H NMR (CDCl3) δ:
1.00-1.30 (5H, m), 1.35-1.50 (2H, m), 1.70-1.85 (2H, m), 2.0-
2.10 (2H, m), 2.45-2.55 (2H, m), 2.55-2.65 (4H, m), 2.85-
3.95 (4H, m), 3.13 (3H, s), 3.83 (3H, s), 3.85 (1H, br m), 5.35
(1H, d, J ) 8 Hz), 6.20 (1H, d, J ) 16 Hz), 6.88 (2H, d, J ) 8
Hz), 6.97-7.05 (2H, m), 7.11 (1H, d, J ) 8 Hz), 7.43 (2H, d, J
) 8 Hz), 7.55 (1H, d, J ) 16 Hz). Mass Spectrum (API+):
Found 527 (MH+). C29H38N2O5S requires 526. The purity was
determined as >98% by LC-MS, retention time 0.84 min.
tr a n s-3-(2-(4-((3-(3-Met h oxyp h en yl)p r op -2-en yl)ca r -
boxa m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-
tetr a h yd r o-1H-3-ben za zep in e (22). 1H NMR (CDCl3) δ:
1.00-1.30 (5H, m), 1.35-1.50 (2H, m), 1.70-1.85 (2H, m), 2.0-
2.10 (2H, m), 2.45-2.55 (2H, m), 2.55-2.65 (4H, m), 2.85-
3.95 (4H, m), 3.13 (3H, s), 3.82 (3H, s), 3.85 (1H, br m), 5.47
tr a n s-3-(2-(4-Am in ocycloh exyl)eth yl)-7-m eth ylsu lfon yl-
oxy-2,3,4,5-tetr a h yd r o-1H-3-ben za zep in e (17). A solution
of trans-3-(2-(4-(N-tert-butoxycarbonylamino)cyclohexyl)ethyl)-
7-methylsulfonyloxy-2,3,4,5-tetrahydro-1H-3-benzazepine 16
(2.45 g, 5.3 mmol), trifluoroacetic acid (8 mL), and dichlo-
romethane (32 mL) were stirred at room temperature, under
argon, for 2 h. The solvents were then evaporated in vacuo,
and the residue was partitioned between water (150 mL) and
ethyl acetate (60 mL). The aqueous layer was removed and
washed with ethyl acetate (50 mL). The aqueous layer was
then basified (pH ) 14) with a 40% solution of sodium
hydroxide. The resultant suspension was extracted with ethyl
acetate (3 × 80 mL), and the combined organic extracts were
dried (Na2SO4). The solvent was evaporated in vacuo to give
1
17 (1.79 g, 93%) as an oil. H NMR (CDCl3) δ: 0.95-1.45 (7H,
m), 1.70-1.80 (2H, m), 1.80-1.90 (2H, m), 2.49 (2H, t, J ) 8

4960 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Macdonald et al.
(1H, d, J ) 8 Hz), 6.35 (1H, d, J ) 16 Hz), 6.85-6.90 (1H, m),
6.95-7.15 (5H, m), 7.27 (1H, t, J ) 7 Hz), 7.56 (1H, d, J ) 16
Hz). Mass Spectrum (API+): Found 527 (MH+). C29H38N2O5S
requires 526. The purity was determined as >98% by LC-MS,
retention time 0.86 min.
m), 7.80 (1H, br s). Mass Spectrum (API+): Found 536 (MH+).
C
30H37N3O4S requires 535.
tr a n s-3-(2-(4-((3-(2-(4-Meth yloxa zolyl))p h en yl)ca r box-
a m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (31). 1H NMR (CDCl3) δ: 1.10-
1.35 (5H, m), 1.40-1.50 (2H, m), 1.80-1.90 (2H, m), 2.05-
2.15 (2H, m), 2.27 (3H, s), 2.45-2.55 (2H, m), 2.60-2.70 (4H,
m), 2.85-2.95 (4H, m), 3.13 (3H, s), 3.90-4.00 (1H, m), 6.05
(1H, d, J ) 8 Hz), 7.00-7.05 (2H, m), 7.10 (1H, d, J ) 9 Hz),
7.45-7.60 (2H, m), 7.90-7.95 (1H, d), 8.05-8.15 (1H, d, J )
8 Hz), 8.3 (1H, s). Mass Spectrum (API+): Found 552 (MH+).
tr a n s-3-(2-(4-((3-(2-Met h oxyp h en yl)p r op -2-en yl)ca r -
boxa m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-
tetr a h yd r o-1H-3-ben za zep in e (23). 1H NMR (CDCl3) δ:
1.00-1.30 (5H, m), 1.35-1.50 (2H, m), 1.70-1.85 (2H, m), 2.0-
2.10 (2H, m), 2.45-2.55 (2H, m), 2.55-2.65 (4H, m), 2.85-
3.95 (4H, m), 3.13 (3H, s), 3.85 (1H, br m), 3.88 (3H, s), 5.40
(1H, d, J ) 8 Hz), 6.47 (1H, d, J ) 16 Hz), 6.85-7.05 (4H, m),
7.13 (1H, d, J ) 7 Hz), 7.31 (1H, m), 7.45 (1H, dd, J ) 7.5, 1.5
Hz), 7.80 (1H, d, J ) 16 Hz). Mass Spectrum (API+): Found
527 (MH+). C29H38N2O5S requires 526.
C
30H37N3O5S requires 552. The purity was determined as
>98% by LC-MS, retention time 0.84 min.
tr a n s-3-(2-(4-(3-(5-(3-Meth ylisoxa zolyl)p h en yl)ca r box-
a m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (32). 1H NMR (CDCl3) δ: 1.10-
1.40 (5H, m), 1.40-1.55 (2H, m), 1.70-1.80 (2H, m), 2.05-
2.20 (2H, m), 2.37 (3H, s), 2.45-2.60 (2H, m), 2.60-2.70 (4H,
m), 2.85-3.00 (4H, m), 3.13 (3H, s), 3.85-4.05 (1H, m), 6.00
(1H, d, J ) 8 Hz), 6.45 (1H, s), 6.95-7.05 (2H, m), 7.05-7.15
(1H, m), 7.52 (1H, t, J ) 9 Hz), 7.75-7.90 (2H, m), 8.10 (1H,
s). Mass Spectrum (API+): Found 552 (MH+). C30H37N3O5S
requires 551.
tr a n s-3-(2-(4-((1-Na p h th a len yl)ca r boxa m id o)cycloh ex-
yl)et h yl)-7-m et h ylsu lfon yloxy-2,3,4,5-t et r a h yd r o-1H -3-
ben za zep in e (24). 1H NMR (CDCl3) δ: 1.15-1.30 (5H, m),
1.45-1.50 (2H, m), 1.80-1.90 (2H, m), 2.15-2.25 (2H, m),
2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.85-2.95 (4H, m), 3.13
(3H, s), 4.00-4.05 (1H, m), 5.78 (1H, d, J ) 8 Hz), 7.00-7.05
(2H, m), 7.10 (1H, d), 7.40-7.60 (4H, m), 7.80-7.90 (2H, m),
8.28 (1H, m). Mass Spectrum (API+): Found 521 (MH+).
tr a n s-3-(2-(4-((3-(2-(5-Meth yloxa zolyl))p h en yl)ca r box-
a m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (33). 1H NMR (CDCl3) δ: 1.10-
1.35 (5H, m), 1.40-1.50 (2H, m), 1.80-1.90 (2H, m), 2.05-
2.15 (2H, m), 2.41 (3H, s), 2.45-2.55 (2H, m), 2.60-2.70 (4H,
m), 2.90-2.95 (4H, m), 3.13 (3H, s), 3.90-4.00 (1H, m), 6.03
(1H, d, J ) 8 Hz), 6.86 (1H, br s), 7.00-7.05 (2H, m), 7.10-
7.15 (1H, m), 7.52 (1H, t, J ) 8 Hz), 7.90-7.95 (1H, m), 8.05-
8.10 (1H, m), 8.30 (1H, br s). Mass Spectrum (API+): Found
552 (MH+). C30H37N3O5S requires 551.
C
30H36N2O4S requires 520. The purity was determined as
>98% by LC-MS, retention time 0.87 min.
tr a n s-3-(2-(4-((5-Qu in olin yl)ca r boxa m id o)cycloh exyl)-
eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tetr a h yd r o-1H-3-ben z-
1
a zep in e (25). H NMR (CDCl3) δ: 1.15-1.35 (5H, m), 1.40-
1.50 (2H, m), 1.80-1.90 (2H, m), 2.15-2.25 (2H, m), 2.45-
2.55 (2H, m), 2.60-2.70 (4H, m), 2.90-2.95 (4H, m), 3.13 (3H,
s), 4.00-4.05 (1H, m), 5.85 (1H, d, J ) 8 Hz), 7.00-7.05 (2H,
m), 7.10 (1H, d, J ) 8 Hz), 7.45-7.50 (1H, m), 7.60-7.70 (2H,
m), 8.17 (1H, d, J ) 8 Hz), 8.72 (1H, d), 8.95(1H, m). Mass
Spectrum (API+): Found 522 (MH+). C29H35N3O4S requires
521. The purity was determined as >98% by LC-MS, retention
time 0.71 min.
tr a n s-3-(2-(4-((3-(2-p yr im id in yl)p h en yl)ca r boxa m id o)-
cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tetr ah ydr o-
1H-3-ben za zep in e (34). 1H NMR (CDCl3) δ: 1.10-1.35 (5H,
m), 1.40-1.50 (2H, m), 1.80-1.90 (2H, m), 2.05-2.15 (2H, m),
2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.85-2.95 (4H, m), 3.13
(3H, s), 3.90-4.00 (1H, m), 6.10 (1H, d, J ) 8 Hz), 7.00-7.05
(2H, m), 7.11 (1H, d, J ) 8 Hz), 7.20-7.30 (2H, m), 7.58 (1H,
t, J ) 8 Hz), 8.00 (1H, d, J ) 8 Hz), 8.58 (1H, d, J ) 8 Hz),
8.70 (1H, s) 8.84 (1H, d, J ) 5 Hz). Mass Spectrum (API+):
Found 549 (MH+). C30H36N4O4S requires 548. The purity was
determined as >98% by LC-MS, retention time 0.79 min.
2,3,4,5-Tetr a h yd r o-1H-3-ben za zep in e (36). To a suspen-
sion of Raney Ni (2.00 g) (prewashed with ethanol (3 × 20 mL))
in ethanol (50 mL) was added a solution of 1,2-phenylenedi-
acetonitrile 35 (7.50 g, 48 mmol) in 2 M NH3 in ethanol (100
mL). The mixture was then hydrogenated at 50 °C and 1000
psi pressure, with shaking, for 24 h. The reaction mixture was
then cooled to room temperature, filtered through a pad of
Kieselguhr, and washed with ethanol (100 mL). The filtrate
was then evaporated in vacuo to give a brown oil which was
purified by column chromatography (silica gel, 2-10% metha-
nol: CH2Cl2) to give 36 as a brown oil (4.25 g, 60%). Mass
spectrum (API+) Found: 148 (MH+). C10H13N requires 147.
3-Acetyl-2,3,4,5-tetr a h yd r o-1H-3-ben za zep in e (37). A
solution of acetic anhydride (6.37 g, 0.062 mol) in dichlo-
romethane (50 mL) was added dropwise to a stirred solution
of 2,3,4,5-tetrahydro-1H-3-benzazepine 36 (8.35 g, 0.057 mol)
and triethylamine (8.7 mL) in dichloromethane (50 mL) at 0
°C under argon. After the mixture was stirred at room
temperature for 18 h, water (80 mL) was added and the organic
layer separated. The organic layer was washed with 0.5 M
hydrochloric acid (50 mL), a saturated solution of sodium
bicarbonate (50 mL), water (50 mL), and then dried (Na2SO4).
Evaporation of the solvent in vacuo gave 37 (10.24 g, 95%) as
tr a n s-3-(2-(4-((4-(2-Met h ylq u in olin yl))ca r b oxa m id o)-
cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tetr ah ydr o-
1H-3-ben za zep in e (27). 1H NMR (CDCl3) δ: 1.10-1.30 (5H,
m), 1.45-1.50 (2H, m), 1.80-1.90 (2H, m), 2.15-2.20 (2H, m),
2.50-2.55 (2H, m), 2.60-2.65 (4H, m), 2.73 (3H, s), 2.90-3.00
(4H, m), 3.13 (3H, s), 4.00-4.15 (1H, m), 5.92 (1H, d, J ) 8
Hz), 7.00-7.15 (3H, m), 7.30 (1H, br s), 7.50-7.55 (1H, m),
7.70-7.75 (1H, m), 8.00-8.15 (2H, d). Mass Spectrum (API+):
Found 536 (MH+). C30H37N3O4S requires 535. The purity was
determined as >98% by LC-MS, retention time 0.73 min.
tr a n s-3-(2-(4-((3-(3-(5-Meth yl-1,2,4-oxadiazolyl))ph en yl)-
ca r b oxa m id o)cycloh exyl)et h yl)-7-m et h ylsu lfon yloxy-
2,3,4,5-tetr a h yd r o-1H-3-ben za zep in e (28). 1H NMR (CDCl3)
δ: 1.10-1.30 (5H, m), 1.40-1.50 (2H, m), 1.80-1.85 (2H, m),
2.05-2.15 (2H, m), 2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.68
(3H, s), 2.90-2.95 (4H, m), 3.13 (3H, s), 3.90-4.00 (1H, m),
6.00 (1H, d, J ) 8 Hz), 7.00-7.05 (2H, m), 7.10 (1H, d, J ) 8
Hz), 7.57 (1H, t, J ) 8 Hz), 7.95-8.00 (1H, m), 8.20 (1H, d),
8.32 (1H, s). Mass Spectrum (API+): Found 553 (MH+).
C
29H36N4O5S requires 552.
tr a n s-3-(2-(4-((3-(5-(2-Meth yloxa zolyl))p h en yl)ca r box-
a m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (29). 1H NMR (CDCl3) δ: 1.10-
1.35 (5H, m), 1.40-1.50 (2H, m), 1.80-1.90 (2H, m), 2.10-
2.20 (2H, m), 2.49 (2H, t, J ) 8 Hz), 2.55 (3H, s), 2.60-2.70
(4H, m), 2.85-2.95 (4H, m), 3.13 (3H, s), 3.90-4.00 (1H, m),
5.92 (1H, d, J ) 8 Hz), 7.00-7.05 (2H, m), 7.10 (1H, d, J ) 8
Hz), 7.25 (1H, m), 7.45 (1H, t, J ) 8 Hz), 7.60-7.75 (2H, m),
8.30 (1H, s). Mass Spectrum (API+): Found 552 (MH+).
C
30H37N3O5S requires 552.
1
a yellow oil which solidified on standing. H NMR (CDCl3) δ:
tr a n s-3-(2-(4-((3-(N-P yr r olyl)p h en yl)ca r boxa m id o)cy-
2.18 (3H, s), 2.85-3.00 (4H, m), 3.55-3.60 (2H, m), 3.72-3.80
(2H, m), 7.10-7.20 (4H, m). Mass Spectrum (API+): Found
190 (MH+). C12H15NO requires 189.
3-Acetyl-7-ch lor osu lfon yl-2,3,4,5-tetr ah ydr o-1H-3-ben z-
a zep in e (38). A solution of 3-acetyl-2,3,4,5-tetrahydro-1H-3-
benzazepine 37 (4.0 g, 0.021 mol) in dichloromethane (25 mL)
cloh exyl)eth yl)-7-m eth ylsu lfon yloxy-2,3,4,5-tetr a h yd r o-
1H-3-ben za zep in e (30). 1H NMR (CDCl3) δ: 1.10-1.30 (5H,
m), 1.40-1.50 (2H, m), 1.80-1.85 (2H, m), 2.10-2.15 (2H, m),
2.45-2.55 (2H, m), 2.60-2.65 (4H, m), 2.90-2.95 (4H, m), 3.13
(3H, s), 3.90-4.00 (1H, m), 5.95 (1H, d, J ) 8 Hz), 6.35-6.40
(2H, m), 7.00-7.05 (2H, m), 7.10-7.15 (3H, m), 7.45-7.55 (3H,

New Dopamine D3 Receptor Antagonist
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4961
was added dropwise to a stirred solution of chlorosulfonic acid
in dichloromethane (25 mL) at -70 °C under argon. After being
warmed to room temperature, the reaction was stirred for 18
h and then poured onto ice/water (200 mL). The resultant
mixture was then extracted with ethyl acetate (3 × 100 mL)
and dried (Na2SO4) and the solvent evaporated in vacuo to give
38 (2.74 g, 45%) as a pale yellow solid. 1H NMR δ (CDCl3):
2.21 (3H, s), 3.0-3.10 (4H, m), 3.60-3.70 (2H, m), 3.74-3.80
(2H, m), 7.35-7.40 (1H, m), 7.80-7.85 (2H, m). Mass spectrum
(API+): Found 288 & 290 (MH+). C12H14ClNO3S requires 287
& 289.
ethyl acetate (30 mL), and then basified (pH ) 14) with a 40%
solution of sodium hydroxide. The oily suspension was then
extracted with ethyl acetate (3 × 60 mL), and the combined
organic layers were dried (Na2SO4). The solvent was evapo-
rated in vacuo to give 42 (1.00 g, 99%) as an off-white solid.
1H NMR (CDCl3) δ: 0.90-1.12 (4H, m), 1.15-1.22 (1H, m),
1.35-1.40 (2H, m), 1.72-1.78 (2H, m), 1.82-1.90 (2H, m),
2.45-2.52 (2H, m), 2.55-2.62 (5H, m), 2.98-3.02 (4H, m), 3.04
(3H, s), 7.27 (1H, d, J ) 7.8 Hz), 7.56 (1H, s), 7.68 (1H, d).
Mass spectrum (API+) 351 (MH+). C19H30N2O2S requires 350.
The following compounds were prepared in a manner similar
to compound 26.
3-Acetyl-7-m eth ylsu lfon yl-2,3,4,5-tetr ah ydr o-1H-3-ben z-
a zep in e (39). To a stirred solution of sodium sulfite (1.60 g,
12. 6 mmol) and sodium hydrogen carbonate (1.14 g, 13.56
mmol) in water (25 mL) was added 3-acetyl-7-chlorosulfonyl-
2,3,4,5-tetrahydro-1H-3-benzazepine 38 (2.60 g, 9.03 mmol) in
tetrahydrofuran (10 mL). The reaction mixture was heated at
75 °C for 2 h and cooled to 30 °C and methyl iodide (2.8 mL,
45.2 mmol) added. After being stirred at 50 °C for 24 h, the
reaction mixture was cooled to room temperature and parti-
tioned between water (50 mL) and ethyl acetate (100 mL). The
aqueous layer was then separated and further extracted with
ethyl acetate (2 × 80 mL). The combined extracts were then
dried (Na2SO4), and the solvent was evaporated in vacuo to
tr a n s-3-(2-(4-((3-(4-F lu or op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr a h y-
1
d r o-1H-3-ben za zep in e (43). H NMR (CDCl3) δ: 1.05-1.20
(5H, m), 1.40-1.45 (2H, m), 1.75-1.85 (2H, m), 2.05-2.15 (2H,
m), 2.50-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-3.05 (4H, m),
3.05 (3H, s), 3.80-3.90 (1H, m), 5.43 (1H, d, J ) 8 Hz), 6.26
(1H, d, J ) 16 Hz), 7.00-7.05 (2H, m), 7.25 (1H, m), 7.45-
7.55 (2H, m), 7.56 (1H, d, J ) 16 Hz), 7.65-7.70 (2H, m). Mass
Spectrum (API+): Found 499 (MH+). C28H35FN2O3S requires
498. The purity was determined as >98% by LC-MS, retention
time 0.80 min.
tr a n s-3-(2-(4-((3-(3-F lu or op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr a h y-
1
give 39 (1.77 g, 73%) as a pale yellow solid. H NMR (CDCl3)
1
2.20 (3H, s), 2.99-3.05 (4H, m), 3.06 (3H, s), 3.61-3.64 (2H,
m), 3.73-3.77 (2H, m), 7.32-7.37 (1H, m), 7.7-7.75 (2H, m).
Mass Spectrum (API+) Found 268 (MH+). C13H17NO3S requires
267.
d r o-1H-3-ben za zep in e (44). H NMR (CDCl3) δ: 1.05-1.30
(5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m), 2.00-2.10 (2H,
m), 2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-3.05 (4H, m),
3.05 (3H, s), 3.80-3.90 (1H, m), 5.44 (1H, d, J ) 8 Hz), 6.33
(1H, d, J ) 16 Hz), 6.95-7.05 (1H, m), 7.10-7.40 (4H, m), 7.56
(1H, d, J ) 16 Hz), 7.60-7.70 (2H, m). Mass Spectrum
(API+): Found 499 (MH+). C28H35FN2O3S requires 498.
tr a n s-3-(2-(4-((3-(2-F lu or op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr a h y-
7-Me t h ylsu lfon yl-2,3,4,5-t e t r a h yd r o-1H -3-b e n za ze -
p in e (40). A solution of 3-acetyl-7-methylsulfonyl-2,3,4,5-tetra-
hydro-1H-3-benzazepine 39 (1.75 g, 6.55 mmol) in 5 M
hydrochloric acid (50 mL) was heated at reflux for 18 h. The
reaction mixture was then cooled to room temperature and
basified (pH ) 12) with solid potassium carbonate, and the
solvent was evaporated in vacuo. The solid residue was
redissolved in water (20 mL) and extracted with ethyl acetate
(5 × 60 mL), and then the combined extracts were dried
(Na2SO4). The solvent was then evaporated in vacuo to give
40 (1.40 g, 95%) as a pale yellow oil. 1H NMR (CDCl3) 1.88
(1H, br s), 2.95-3.13 (8H, m), 3.04 (3H, s), 7.25-7.30 (1H, d),
7.65-7.72 (2H, m). Mass Spectrum (API+): Found 226 (MH+).
1
d r o-1H-3-ben za zep in e (45). H NMR (CDCl3) δ: 1.10-1.30
(5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m), 2.05-2.15 (2H,
m), 2.50 (2H, t, J ) 7 Hz), 2.60-2.70 (4H, m), 2.95-3.05 (4H,
m), 3.05 (3H, s), 3.80-3.95 (1H, m), 5.43 (1H, d, J ) 8 Hz),
6.48 (1H, d, J ) 16 Hz), 7.05-7.15 (2H, m), 7.20-7.40 (2H,
m), 7.45-7.50 (1H, m), 7.65-7.75 (3H, m). Mass Spectrum
(API+): Found 499 (MH+). C28H35FN2O3S requires 498.
tr a n s-3-(2-(4-((3-(3,5-Diflu or op h en yl)p r op -2-en yl)ca r -
boxa m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (46). 1H NMR (CDCl3) δ: 1.00-
1.30 (5H, m), 1.35-1.50 (2H, m), 1.70-1.85 (2H, m), 2.0-2.15
(2H, m), 2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-3.05 (7H,
m), 3.85 (1H, br m), 5.50 (1H, d, J ) 8 Hz), 6.35 (1H, d, J ) 16
Hz), 6.70-6.80 (1H, m), 6.95-7.05 (2H, m), 7.28 (1H, d, J ) 7
Hz), 7.50 (1H, d, J ) 16 Hz), 7.65-7.70 (2H, m). Mass
Spectrum (API+): Found 517 (MH+). C28H34F2N2O3S requires
516. The purity was determined as >98% by LC-MS, retention
time 0.83 min.
C
11H15NO2S requires 225.
tr a n s-3-(2-(4-(N-ter t-Bu toxycar bon ylam in o)cycloh exyl)-
eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr a h yd r o-1H-3-ben za ze-
p in e (41). A solution of 7-methylsulfonyl-2,3,4,5-tetrahydro-
1H-3-benzazepine 40 (1.00 g, 4.44 mmol) and trans-(1-(4-N-
tert-butoxycarbonyl)amino)cyclohexyl acetaldehyde 15 (1.07 g,
4.44 mmol) in 1,2-dichloroethane (20 mL) was stirred at room
temperature for 5 min before sodium triacetoxyborohydride
(0.99 g, 4.66 mmol) was added in a single portion. After being
stirred at room temperature for 48 h, the reaction mixture was
partitioned between water (50 mL) and dichloromethane (100
mL). The aqueous layer was separated and reextracted with
dichloromethane (2 × 50 mL), and the combined organic layers
were dried (Na2SO4). The solvent was then evaporated in vacuo
to give a pale yellow solid which was purified by column
chromatography (silica gel, ethyl acetate:methanol; 9:1) to give
41 (1.80 g, 90%) as a colorless solid. 1H NMR (CDCl3) δ:
0.99-1.14 (4H, m), 1.23-1.29 (1H, m), 1.41-1.46 (2H, m), 1.46
(9H, s), 1.73-1.79 (2H, m), 2.00-2.06 (2H, m), 2.50 (2H, t, J
) 7.6 Hz), 2.62-2.65 (4H, m), 2.99-3.02 (4H, m), 3.05 (3H, s),
3.38 (1H, br s), 4.38 (1H, br s), 7.27-7.30 (1H, d), 7.67-7.74
(2H, m). Mass spectrum: (API+) Found: 351 (M - Boc)H+.
tr a n s-3-(2-(4-((3-(2,6-Diflu or op h en yl)p r op -2-en yl)ca r -
boxa m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (47). 1H NMR (CDCl3) δ: 1.00-
1.30 (5H, m), 1.35-1.50 (2H, m), 1.70-1.85 (2H, m), 2.00-
2.15 (2H, m), 2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-
3.05 (7H, m), 3.87 (1H, br m), 5.45 (1H, d, J ) 8 Hz), 6.66
(1H, d, J ) 16 Hz), 6.80-7.00 (2H, m), 7.20-7.35 (2H, m),
7.60-7.75 (3H, m). Mass Spectrum (API+): Found 517 (MH+).
C
28H34F2N2O3S requires 516. The purity was determined as
>98% by LC-MS, retention time 0.82 min.
tr a n s-3-(2-(4-((3-(4-Cya n op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr a h y-
d r o-1H-3-ben za zep in e (48). 1H NMR (CDCl3) δ: 1.00-
1.3(5H, m), 1.35-1.50 (2H, m), 1.70-1.85 (2H, m), 2.0-2.15
(2H, m), 2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-3.05 (7H,
m), 3.85 (1H, br m), 5.55 (1H, d, J ) 8 Hz), 6.43 (1H, d, J ) 16
Hz), 7.28 (1H, d, J ) 7 Hz), 7.50-7.70 (7H, m). Mass Spectrum
(API+): Found 506 (MH+). C29H35N3O3S requires 505. The
purity was determined as >98% by LC-MS, retention time 0.75
min.
C
24H38N2O4S requires 450.
tr a n s-3-(2-(4-Am in ocycloh exyl)eth yl)-7-m eth ylsu lfon yl-
2,3,4,5-tetr a h yd r o-1H-3-ben za zep in e (42). A solution of
trans-3-(2-(1-(4-N-tert-butoxycarbonyl)amino)cyclohexyl)ethyl-
7-methylsulfonyl-2,3,4,5-tetrahydro-1H-3-benzazepine 41 (1.3
g, 2.89 mmol) in dichloromethane (24 mL) and trifluoroacetic
acid (6 mL) was stirred at room temperature for 2 h. The
reaction mixture was then concentrated in vacuo and the
residue partitioned between water (60 mL) and ethyl acetate
(20 mL). The aqueous layer was separated, extracted with
tr a n s-3-(2-(4-((3-(3-Cya n op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr a h y-

4962 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Macdonald et al.
1
d r o-1H-3-ben za zep in e (49). H NMR (CDCl3) δ: 1.00-1.30
8 Hz), 6.86 (1H, d, J ) 1 Hz), 7.25 (1H, d, J ) 11 Hz), 7.45-
7.55 (1H, m), 7.60-7.70 (2H, m), 7.89 (1H, d, J ) 8 Hz), 8.10
(1H, d, J ) 8 Hz), 8.29 (1H, s). Mass Spectrum (API+): Found
536 (MH+). C30H37N3O4S requires 535.
(5H, m), 1.35-1.50 (2H, m), 1.70-1.85 (2H, m), 2.0-2.15 (2H,
m), 2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-3.05 (7H, m),
3.85 (1H, br m), 5.50 (1H, d, J ) 8 Hz), 6.39 (1H, d, J ) 16
Hz), 7.28 (1H, d, J ) 7 Hz), 7.45-7.80 (7H, m). Mass Spectrum
(API+): Found 506 (MH+). C29H35N3O3S requires 505. The
purity was determined as >98% by LC-MS, retention time 0.76
min.
tr a n s-3-(2-(4-((3-(5-(3-Met h ylisoxa zolyl))p h en yl)ca r -
boxa m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tet-
r a h yd r o-1H-3-ben za zep in e (57). 1H NMR (CDCl3) δ: 1.05-
1.45 (5H, m), 1.50-1.60 (2H, m), 1.75-1.90 (2H, m), 2.05-
2.20 (2H, m), 2.37 (3H, s), 2.50-2.60 (2H, m), 2.60-2.70 (4H,
m), 2.95-3.10 (4H, m), 3.05 (3H, s), 3.85-4.05 (1H, m), 6.03
(1H, d, J ) 8 Hz), 6.45 (1H, s), 7.25-7.30 (1H, m), 7.52 (1H, t,
J ) 9 Hz)), 7.60-7.75 (2H, m), 7.80-7.90 (2H, m), 8.12 (1H,
s). Mass Spectrum (API+): Found 536 (MH+). C30H37N3O4S
requires 535.
tr a n s-3-(2-(4-((3-(3-(5-Meth yl-1,2,4-oxadiazolyl))ph en yl)-
ca r boxa m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-
tetr a h yd r o-1H-3-ben za zep in e (58). 1H NMR (CDCl3) δ:
1.05-1.35 (5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m),
2.05-2.15 (2H, m), 2.41 (3H, s), 2.45-2.55 (2H, m), 2.60-2.70
(4H, m), 2.95-3.05 (4H, m), 3.04 (3H, s), 3.90-4.00 (1H, m),
6.03 (1H, d, J ) 8 Hz), 7.25 (1H, d, J ) 11 Hz), 7.45-7.55
(1H, m), 7.60-7.70 (2H, m), 7.89 (1H, d, J ) 8 Hz), 8.10 (1H,
d, J ) 8 Hz), 8.29 (1H, s). Mass Spectrum (API+): Found 537
(MH+). C29H36N4O4S requires 536.
Biologica l Test Meth od s. In vivo studies were conducted
in compliance with the Home Office Guidance on the operation
of UK Animals (Scientific Procedures) Act 1986 and were
approved by the SmithKline Beecham Procedures Review
Panel.
Clon ed Cell Lin es Exp r essin g D2 a n d D3 Recep tor s.
Human cloned D2 (long) receptors (hD2) expressed in CHO cells
were obtained from the Garvan Intitute of Medical Research,
Sydney, Australia. Human cloned D3 receptors (hD3) expressed
in CHO or NG108-15 cells were obtained from Unite de
Neurobiologie et Pharmacologie (U.109) de l’INSERM, Paris,
France.
Ra d ioliga n d Bin d in g Assa ys. Radioligand binding assays
at hD2 and hD3 receptors were carried out using membranes
from CHO cells. Membranes (5-15 mg of protein) were
incubated with with 0.1 nM [125I]iodosulpride in a buffer
containing 50 mM Tris-HCl, 120 mM NaCl, 5 mM KCl, 2 mM
CaCl2, and 1 mM MgCl2 (pH 7.4) for 30 min at 37 °C in the
presence or absence of competing ligands. Nonspecific binding
was defined with 0.1 mM iodosulpride. Radioligand binding
assays were also performed on 55 receptors, ion channels, and
enzymes by CEREP, Le Bois l’Eveque, B. P. 1,86000 Celle
L’Evescault, France.
Cell Cu ltu r e. CHO cells expressing hD2 receptors were
grown in 50:50 Dulbecco’s Modified Eagles Medium (DMEM;
without sodium pyruvate, with glucose):Ham’s F-12 containing
10% (v/v) foetal bovine serum (FBS). For hD3 CHO clones, the
growth medium was DMEM (without sodium pyruvate, with
glucose) containing 10% FBS, 100 nM methotrexate, 2 nM
glutamine, 500 nM (-)-sulpiride, and 1% (v/v) essential amino
acids. Cells were removed from confluent plates by scraping
and were harvested by centrifugation (200g, 5 min, room
temperature). Following resuspension in 10 mL of fresh culture
medium, an aliquot was counted and the cells passaged at
12 500 or 25 000 cells cm2. Cultures between passages 5 and
30 were used for functional studies.
Deter m in a tion of Extr a cellu la r Acid ifica tion r a tes in
Micr op h ysiom eter . Cells were seeded into 12 mm transwell
inserts (Costar) at 300 000 cells/cup in FBS-containing growth
medium. The cells were incubated for 6h at 37 °C in 95% O2/
5% CO2, before changing to FBS and sulpiride-free medium.
After a further 16-18 h, cups were loaded into the sensor
chambers of the Cytosensor Microphysiometer (Molecular
Devices). The chambers were perfused with running medium
(bicarbonate-free Dulbecco’s modified Eagles medium contain-
ing 2 mM glutamine and 44 mM NaCl) at a flow rate of 100
µL/min and temperature of 37 °C. Each pump cycle lasted 90
s. The pump was on for the first 60 s and the acidification
rate determined between 68 and 88 s, using the Cytosoft
program. Cells were exposed (4.5 min for hD2, 7.5 min for hD3)
tr a n s-3-(2-(4-((3-(2-Cya n op h en yl)p r op -2-en yl)ca r boxa -
m id o)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr a h y-
1
d r o-1H-3-ben za zep in e (50). H NMR (CDCl3) δ: 1.00-1.30
(5H, m), 1.38-1.50 (2H, m), 1.70-1.85 (2H, m), 2.0-2.15 (2H,
m), 2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-3.05 (7H, m),
3.85 (1H, br m), 5.58 (1H, d, J ) 8 Hz), 6.66 (1H, d, J ) 16
Hz), 7.28 (1H, d, J ) 7 Hz), 7.35-7.50 (1H, m), 7.50-7.71 (5H,
m), 7.77 (1H, d, J ) 16 Hz). Mass Spectrum (API+): Found
506 (MH+). C29H35N3O3S requires 505. The purity was deter-
mined as >98% by LC-MS, retention time 0.77 min.
tr a n s-3-(2-(1-(4-(1-Na p h t h a len yl)ca r b oxa m id o)cyclo-
h exyl)et h yl)-7-m et h ylsu lfon yl-2,3,4,5-t et r a h yd r o-1H -3-
ben za zep in e (51). 1H NMR (CDCl3) δ: 1.10-1.35 (5H, m),
1.40-1.55 (2H, m), 1.75-1.85 (2H, m), 2.15-2.25 (2H, m),
2.50-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-3.05 (4H, m), 3.05
(3H, s), 4.00-4.10 (1H, m), 5.80 (1H, d, J ) 8 Hz), 7.25 (1H,
m), 7.45-7.60 (4H, m), 7.65-7.75 (2H, m), 7.80-7.95 (2H, m),
8.25 (1H, m). Mass Spectrum (API+): Found 505 (MH+).
C
30H36N2O3S requires 504.
tr a n s-3-(2-(4-((5-(2-Met h ylq u in olin yl))ca r b oxa m id o)-
cycloh exyl)et h yl)-7-m et h ylsu lfon yl-2,3,4,5-t et r a h yd r o-
1H-3-ben za zep in e (52). 1H NMR (CDCl3) δ: 1.10-1.30 (5H,
m), 1.45-1.50 (2H, m), 1.80-1.90 (2H, m), 2.15-2.20 (2H, m),
2.50-2.55 (2H, m), 2.60-2.70 (4H, m), 2.75 (3H, s), 2.95-3.05
(4H, m), 3.04 (3H, s), 3.95-4.05 (1H, m), 5.82 (1H, d, J ) 8
Hz), 7.20-7.25 (1H, d, J ) 7 Hz), 7.34 (1H, d, J ) 9 Hz), 7.55-
7.70 (4H, m), 8.05-8.10 (1H, d), 8.62 (1H, d). Mass Spectrum
(API+): Found 520 (MH+). C30H37N3O3S requires 519. The
purity was determined as >98% by LC-MS, retention time 0.58
min.
tr a n s-3-(2-(4-((5-(8-F lu or o-2-m eth ylqu in olin yl))ca r box-
am ido)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr ah y-
1
d r o-1H-3-ben za zep in e (53). H NMR (CDCl3) δ: 1.10-1.30
(5H, m), 1.40-1.50 (2H, m), 1.80-1.90 (2H, m), 2.10-2.20 (2H,
m), 2.45-2.50 (2H, m), 2.55-2.65 (4H, m), 2.80 (3H, s), 2.95-
3.05 (4H, m), 3.04 (3H, s), 3.90-4.00 (1H, m), 5.88 (1H, d, J )
8 Hz), 7.20-7.35 (2H, m), 7.40 (1H, d, J ) 9 Hz), 7.45-7.55
(1H, m), 7.60-7.70 (2H, m), 8.60-8.70 (1H, m). Mass Spectrum
(API+): Found 538 (MH+). C30H36FN3O3S requires 537. The
purity was determined as >98% by LC-MS, retention time 0.69
min.
tr a n s-3-(2-(4-((3-(5-(2-Meth yloxa zolyl))p h en yl)ca r box-
am ido)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr ah y-
1
d r o-1H-3-ben za zep in e (54). H NMR (CDCl3) δ: 1.05-1.35
(5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m), 2.05-2.15 (2H,
m), 2.45-2.55 (2H, m), 2.54 (3H, s), 2.60-2.70 (4H, m), 2.95-
3.05 (4H, m), 3.04 (3H, s), 3.90-4.00 (1H, m), 5.94 (1H, d, J )
8 Hz), 7.15-7.25 (2H, m), 7.45 (1H, t, J ) 8 Hz), 7.60-7.75
(4H, m), 7.98 (1H, br s). Mass Spectrum (API+): Found 536
(MH+). C30H37N3O4S requires 535. The purity was determined
as >98% by LC-MS, retention time 0.74 min.
tr a n s-3-(2-(4-((3-(5-(1-Meth ylp yr a zolyl))p h en yl)ca r box-
am ido)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr ah y-
1
d r o-1H-3-ben za zep in e (55). H NMR (CDCl3) δ: 1.05-1.30
(5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m), 2.05-2.15 (2H,
m), 2.50-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-3.05 (4H, m),
3.05 (3H, s), 3.90 (3H, s), 3.90-3.95 (1H, m), 5.79 (1H, d, J )
8 Hz), 6.35 (1H, d, J ) 2 Hz), 7.25 (1H, d), 7.45-7.55 (3H, m),
7.65-7.80 (3H, m), 7.82 (1H, br s). Mass Spectrum (API+):
Found 535 (MH+). C30H38N4O3S requires 534.
tr a n s-3-(2-(4-((3-(2-(5-Meth yloxa zolyl))p h en yl)ca r box-
am ido)cycloh exyl)eth yl)-7-m eth ylsu lfon yl-2,3,4,5-tetr ah y-
1
d r o-1H-3-ben za zep in e (56). H NMR (CDCl3) δ: 1.05-1.35
(5H, m), 1.40-1.50 (2H, m), 1.75-1.85 (2H, m), 2.05-2.15 (2H,
m), 2.41 (3H, s), 2.45-2.55 (2H, m), 2.60-2.70 (4H, m), 2.95-
3.05 (4H, m), 3.04 (3H, s), 3.90-4.00 (1H, m), 6.03 (1H, d, J )

New Dopamine D3 Receptor Antagonist
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4963
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P 450 In h ibition . Cytochrome P450 inhibition profiles were
determined using the protocols outlined in a number of
patents.29 Inhibition against cytochrome P450 1A2 was deter-
mined as described in the literature.30
Con d ition ed P la ce P r efer en ce. Albino, male Sprague-
Dawley rats (150-175 g at the start of handling, Taconic
Farms, Germantown, NY) were used in all studies. An
automated, three-chambered Conditioned Place Preference
apparatus (Iris Ophthalmic, Mt. Sinai, NY) was used, of which
two chambers were identical in dimensions, the two chambers
being separated by plexiglass guillotine doors. The pairing
chambers were composed of distinct visual and tactile cues.
One of the pairing chambers was entirely white, and the
second chamber had white and black checkered boxes. The two
pairing chambers were separated by a third, neutral connect-
ing tunnel, with white/white with black checkered boxes on
the walls and clear plexiglass floors. Each of the chambers had
an infrared microbeam that was wired to a timer. The beams
were arranged such that when the animals leave one chamber,
a mechanism would shut off the timer. After 3 days habitua-
tion and conditioning to the apparatus, rats (n ) 10 per group)
received four daily pairings each of 15 mg/kg ip of cocaine or
1 mL/kg ip of distilled water. On the test day, the animals
being tested in the expression phase received either vehicle
(2% methylcellulose, 1 mL/kg po) or SB-414796 (0.3, 1, 3, or
10 mg/kg po) 4 h before they were placed in the apparatus
and allowed free access to both the chambers for 15 min. The
time spent in each chamber was recorded as described above.
Ca ta lep sy. Catalepsy was assessed by positioning rats with
their hindpaws on the bench and their forelimbs rested on a
1 cm diameter horizontal bar, 10 cm above the bench. The
length of time in this position was recorded to a maximum of
120 s. Vehicle (1% methylcellulose, 2 mL/kg po) or SB-414796
was injected (2 mL/kg). Catalepsy was assessed 180 and 210
min (for habituation purposes) and 240 min after drug
administration. Rats were judged cataleptic and assigned a
score of 1 if they maintained an immobile attitude for 30 s or
more at the 240 min time point; otherwise, they were given a
score of 0. A logistic regression analysis (SAS-RA, version
6.11; SAS Institute Inc.) was used to analyze the data at the
240 min time point.
P la sm a P r ola ctin Levels. Animals were pretreated with
either haloperidol (3 mg/kg po), SB-414796 (10, 30, or 100 mg/
kg po), or vehicle (1% methylcellulose, 2 mL/kg po). After 2 h,
the animals were decapitated, and the blood was collected into
glass vials. Samples were kept at 4 °C overnight, and then
the serum was separated and stored at -70 °C until subse-
quent assay. Serum prolactin was assayed by radioimmuno-
assay (Amersham Life Sciences). Serum prolactin measures
were transformed (log) prior to analysis by analysis of variance
and Dunnett’s t-test (Statistica Version 6.0)
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