The synthesis and preliminary pharmacological evaluation of a series of substituted 4-phenoxypropyl analogues of the atypical antipsychotic clozapine

Article abstract of DOI:10.1071/CH09345

Herein we report the synthesis, characterization, and preliminary pharmacological activity of a new series of substituted 4′-phenoxypropyl tricyclic analogues of clozapine as potential antipsychotic agents for the treatment of schizophrenia. The lead comp

Full text of DOI:10.1071/CH09345

Full Paper
CSIRO PUBLISHING
Aust. J. Chem. 2010, 63, 116–124
www.publish.csiro.au/journals/ajc
The Synthesis and Preliminary Pharmacological Evaluation
of a Series of Substituted 4ꢀ-Phenoxypropyl Analogues
of the Atypical Antipsychotic Clozapine
Ben Capuano,A,B Ian T. Crosby,A Fiona M. McRobb,A Anna Podloucka,A
David A. Taylor,A Amelia Vom,A and Elizabeth YurievA
AMedicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences,
Monash University (Parkville Campus), 381 Royal Parade, Parkville, Vic. 3052, Australia.
BCorresponding author. Email: ben.capuano@pharm.monash.edu.au
Herein we report the synthesis, characterization, and preliminary pharmacological activity of a new series of substituted
4ꢀ-phenoxypropyl tricyclic analogues of clozapine as potential antipsychotic agents for the treatment of schizophrenia.The
lead compound (3) for this investigation was designed based on a revised model derived from the structural hybridization
of the commercial therapeutics clozapine (1) and haloperidol (2). The compounds described in this paper probe the
biochemical effects of introducing a variety of electron-withdrawing and electron-donating substituents with the primary
focus on the para-position of the introduced distal aromatic ring. The target compounds were readily prepared in three
steps using the key intermediate lactam (8-chloro-10,11-dihydro-5H-dibenzo[b,e][1,4]diazepine-11-one, 9), piperazine
and commercially available substituted phenols. The chemistry and structural characterization of this series of substituted
4ꢀ-phenoxypropyl analogues of clozapine are described. Preliminary in vitro results on the pharmacological effects of the
ring substituents on affinity for dopamine D4 and serotonin 5-HT2A receptors are discussed. Psychosis-related in vivo
animal behavioural data for compounds identified with potential from the receptor binding screen are also presented.
Manuscript received: 18 June 2009.
Manuscript accepted: 27 July 2009.
Introduction
published in an earlier study,[6] pharmacologically exhibited
a clozapine-like profile. Compound 3 was designed based on
a revised model derived from the structural hybridization of
the commercial therapeutics clozapine (1) and haloperidol (2),
and this compound forms the basis of the current investi-
gation. The novel compounds described in the present paper
investigate the biochemical effects of introducing a variety of
electron-withdrawing and electron-donating substituents on the
aryl ring of the phenoxypropyl moiety. Substituents on the
remote ring were chosen on the basis of favourable biochemical
data from previous work.[1] Our primary focus was substituent
effects on the para-position of the remote aromatic ring; par-
ticularly in view of the importance of the fluorine atom in
this para-position of haloperidol, which is necessary for pro-
nounced antipsychotic activity.[7] The novel compounds were
screened for their affinity for the target dopamine D4 and sero-
tonin 5-HT2A receptors. Promising candidates that displayed a
clozapine-like receptor profile were further evaluated for their
potential to antagonize apomorphine-induced climbing in mice,
a psychosis-related behavioural model predictive of mesolim-
bic dopaminergic activity and therefore potential antipsychotic
activity.
Schizophrenia is arguably the most debilitating mental ill-
ness, affecting ∼1% of the world population. The prominent
symptoms of this disease state are divided into positive (hal-
lucinations and delusions) and negative (social and emotional
withdrawal) and also encompass cognitive deficits.[1] The cause
of schizophrenia remains unknown but many hypotheses postu-
late neurotransmitter dysfunction involving dopamine and sero-
tonin. Clozapine(1)(Fig. 1), anarchetypalatypicalantipsychotic
agent, exhibits strong dopamine D4 and serotonin 5-HT2A antag-
onist activity and displays unparalleled efficacy in treatment-
resistant patients.[2] Clozapine is also devoid of extrapyramidal
side effects (EPS) owing to its low striatal dopamine D2 affin-
ity. Unfortunately, clozapine’s propensity to induce a potentially
fatal blood disorder, agranulocytosis,[3,4] in 1–2% of patients
excludes its clinical use as a front-line treatment. The immense
success of haloperidol (2) (Fig. 1) in treating the positive symp-
toms of schizophrenia[5] is attributable to its strong affinity for
mesolimbic dopamine D2 receptors. Of particular interest to our
research group is the synthesis of novel tricyclic chemical enti-
ties that exhibit a ‘clozapine-like’ profile by targeting dopamine
D4 and serotonin 5-HT2A receptors in the central nervous system
(CNS). Strong antagonism of the dopamine D4 and serotonin 5-
HT2A receptors relative to the dopamine D2 receptor is believed
to alleviate positive and negative symptoms, respectively, with-
out causing EPS (Parkinsonian-like movement disorders).
The lead compound, 8-chloro-11-[4-(3-phenoxypropyl)
piperazino]-5H-dibenzo[b,e][1,4]diazepine (3, Y = H) (Fig. 1),
Chemistry
The synthetic approach for the preparation of these novel
susbstituted 4ꢀ-phenoxypropyl analogues of clozapine was
based on initial formation of a series of monosubstituted
piperazines (Scheme 1). Commercially available substituted
© CSIRO 2010
10.1071/CH09345
0004-9425/10/010116

Substituted 4ꢀ-Phenoxypropyl Analogues of the Atypical Antipsychotic Clozapine
117
H
N
H
N
Cl
HO
Cl
N
Cl
N
N
N
N
4ꢀ
O
N
N
Clozapine analogues (3)
Haloperidol (2)
O
Clozapine (1)
H3C
Y ꢁ 2-Cl
3-Cl, 3-Br, 3-CH3
4-F, 4-Cl, 4-Br, 4-CH3, 4-OCH3
F
Y
Fig. 1. The chemical structures of the clinically prescribed antipsychotics, clozapine (1) and haloperidol (2), and the new structural template (3)
selected for investigation.
phenols (4a–h), under alkaline conditions in refluxing 1,3-
dibromopropane, were converted to their corresponding sub-
stituted phenoxypropyl bromides (6a–h). These compounds
were isolated as colourless to yellow liquids in 36–66%
yield. Subsequent treatment of the substituted phenoxypropyl
bromides (6a–h) and commercial 3-(4-fluorophenoxy)propyl
chloride (6i) with piperazine (7) in toluene afforded the
desired monosubstituted piperazines (8a–i) as colourless to
bright yellow liquids in 33–89% yield. Compound 8d (1-(3-
(3-bromophenoxy)propyl)piperazine) was purified by column
chromatography as attempts to distill the product under vac-
uum resulted in significant decomposition of the crude product
and pronounced colouration of the distillate. Interestingly, com-
pounds 8b (Y = 3-Cl), 8d (Y = 3-Br), and 8f (Y = 3-CH3)
are commercially available but not reported in the literature
(SciFinder Scholar 2007).
The target amidines (3a–i) were prepared according to
Scheme2, wherebythesynthesizedmonosubstitutedpiperazines
(as the preformed titanium–amine complex following treatment
with the Lewis acid titanium tetrachloride) were coupled to the
key tricyclic lactam (9),[1] affording yellow crystalline solids
in 32–76% yield (except for 3a and 3d, which yielded yellow
foams). The aforementioned yields are unoptimized and repre-
sent the results of a single reaction. The purity and integrity
of the compounds were supported by microanalysis whereby
the elements C, H, and N were found to be within 0.4%
of their calculated values. Some target compounds, recrystal-
lized from methanol/water, crystallized incorporating methanol
in their crystal structure as indicated by their combustion analy-
sis data. In such cases, the methanol of crystallization was also
evident in their 1H NMR spectra.
analogue of clozapine (3, Y = H, 81% I), compounds 3b–e,
which contained the larger halogen atom (Cl and Br) at the
meta- and para-positions, displayed reduced D4.4 affinity; how-
ever, the difference was only marginal. The affinity of the test
compounds for the serotonin 5-HT2A receptor exhibited greater
differentiation within the series (60–91% I) when compared with
clozapine (85% I) and compound 3 (Y = H, 83% I). The para-Cl
(3c) and para-Br (3e) analogues demonstrated the least inhibi-
tion of radioligand at 67% I and 60% I, respectively. Conversely,
the para-F analogue (3i), which shows a structural similarity
to the para-F of haloperidol, displayed encouraging clozapine-
like affinity (81% I) with an overall trend of F > Cl > Br for
5-HT2A receptor affinity. Interestingly, the inclusion of a CH3
(3f–g) or OCH3 (3h) substituent at the meta- or para-positions
waswelltoleratedatthe5-HT2A receptor. Ingeneral, thereceptor
binding data suggest that substituted 4ꢀ-phenoxpropyl analogues
have a favourable rather than a detrimental effect on dopamine
D4.4 and serotonin 5-HT2A affinity relative to clozapine (1)
and compound 3. Based on the preliminary affinity data from
this receptor binding screen, all compounds were further evalu-
ated in a mouse behavioural assay that is predictive of potential
antipsychotic efficacy.
In Vivo Behavioural Studies
The series of substituted 4ꢀ-phenoxylpropyl analogues of cloza-
pine (3a–i) were evaluated in vivo for their ability to antagonize
apomorphine-induced climbing in mice, a psychosis-related
behavioural model predictive of mesolimbic, dopaminergic
activity and, therefore, potential antipsychotic efficacy.[9–12]
The mice were pretreated with clozapine (10 mg kg−1 intra-
peritoneal (ip)) or the test compounds (10 mg kg−1 ip) as
their hydrochloride salts,[1] 30 min before an injection of apo-
morphine hydrochloride (3 mg kg−1 ip), and their climbing
behaviour observed. The assessed results of this behavioural
assay are displayed in Table 2. Clozapine and compound 3
effectively diminished apomorphine-induced climbing in mice
at 10 mg kg−1 ip, displaying 63 and 71% inhibition of climbing,
respectively. The analogues 3h (Y = 4-OCH3) and 3i (Y = 4-F)
were the prominent compounds and significantly antagonized
the apomorphine-induced climbing behaviour in mice, with
the haloperidol-related p-fluorophenoxypropyl analogue (3i)
displaying the best activity with 76% inhibition of climbing.
Compounds 3a (Y = 2-Cl), 3c (Y = 4-Cl), and 3f (Y = 3-CH3),
although exhibiting promising receptor binding profiles, showed
only marginal anticlimbing activity; however, these values were
determined not to be statistically significant. We were pleased
Receptor Binding Studies
Details of the in vitro assays for the synthesized compounds are
described in the Experimental section. Table 1 lists percentage
inhibition (% I) of radioligand binding at a compound concentra-
tion of 10−6 M for the central dopamine D4.4 (the most common
polymorphic variant of the D4 receptor)[8] and central serotonin
5-HT2A receptors for all test compounds. Data for the compound
corresponding to the 4ꢀ-phenoxylpropyl analogue of clozapine
(3, Y = H) are also included for comparative purposes, thereby
assisting in the development of structure–activity relationships.
Our preliminary pharmacological results were pleasing,
whereby all test compounds showed comparable or better affini-
ties (70–86% I) for the dopamine D4.4 receptor relative to
clozapine (72% I). In comparison with the 4ꢀ-phenoxylpropyl

118
B. Capuano et al.
Cl
Br
O
F
6i
OH
Y
(i)
(ii)
Y
HN
N
O
ꢂ
Br
Br
O
H
N
Y
5
4a Y ꢁ 2-Cl
4b Y ꢁ 3-Cl
4c Y ꢁ 4-Cl
4d Y ꢁ 3-Br
4e Y ꢁ 4-Br
4f Y ꢁ 3-CH3
4g Y ꢁ 4-CH3
4h Y ꢁ 4-OCH3
6a Y ꢁ 2-Cl
6b Y ꢁ 3-Cl
6c Y ꢁ 4-Cl
6d Y ꢁ 3-Br
6e Y ꢁ 4-Br
6f Y ꢁ 3-CH3
6g Y ꢁ 4-CH3
6h Y ꢁ 4-OCH3
8a Y ꢁ 2-Cl
8b Y ꢁ 3-Cl
8c Y ꢁ 4-Cl
8d Y ꢁ 3-Br
8e Y ꢁ 4-Br
8f Y ꢁ 3-CH3
8g Y ꢁ 4-CH3
8h Y ꢁ 4-OCH3
8i Y ꢁ 4-F
N
H
7
Scheme 1. Reagents and conditions: (i) NaOH(aq), reflux, 2–3 h; (ii) toluene, 85◦C.
H
N
Cl
N
H
N
N
Y
(i)
HN
N
4ꢀ
ꢂ
O
Cl
N
3a Y ꢁ 2-Cl
3b Y ꢁ 3-Cl
3c Y ꢁ 4-Cl
3d Y ꢁ 3-Br
3e Y ꢁ 4-Br
3f Y ꢁ 3-CH3
3g Y ꢁ 4-CH3
3h Y ꢁ 4-OCH3
3i Y ꢁ 4-F
NH
8a Y ꢁ 2-Cl
8b Y ꢁ 3-Cl
8c Y ꢁ 4-Cl
8d Y ꢁ 3-Br
8e Y ꢁ 4-Br
8f Y ꢁ 3-CH3
8g Y ꢁ 4-CH3
8h Y ꢁ 4-OCH3
8i Y ꢁ 4-F
O
O
9
Y
Scheme 2. Reagents and conditions: (i) TiCl4, anisole, 25 to 55◦C, reflux.
to observe that compound 3e (Y = 4-Br), which exhibited the
least favourable receptor binding profile, was equivalent in
potency to the vehicle and displayed no anticlimbing activity
whatsoever. On the whole, the in vivo data suggest that ring
substitution of the introduced aryl ring of 3 with the desig-
nated electron-withdrawing and electron-donating groups has
quite a variable effect on behavioural activity with no definitive
structure–activity correlation. This may be attributed to insuffi-
cient receptor binding data at target and other receptor systems
implicated in this complex behavioural model, thereby making
it difficult to infer a correlation between in vitro binding data
and in vivo behavioural findings. Pharmacokinetic factors may
also influence the variability of the intercompound relationship
from a pharmacological point of view.
3c (Y = 4-Cl), and 3e (Y = 4-Br) demonstrating reduced inhi-
bition of radioligand at the 5-HT2A receptor. From the binding
data, it was proposed that both receptor systems are certainly tol-
erant to ring substitution of the aryl system, with reduced activity
associated with the larger halogens in the para-position.
An in vivo behavioural investigation of this series iden-
tified two noteworthy target compounds 3h (Y = 4-OCH3)
and 3i (Y = 4-F) that significantly diminished apomorphine-
induced climbing in mice with the haloperidol-derived p-
fluorophenoxypropyl analogue (3i) as the standout.These results
compared favourably with the anticlimbing properties of clozap-
ine and compound 3.An interesting structural feature associated
with 3h and 3i is that both substituents are located at the
para-position and contain the hydrogen-bonding acceptor atoms
oxygen and fluorine, respectively. These atoms may be involved
in a key hydrogen-bond interaction with a significant amino
acid residue(s) of the target receptors, thereby highlighting and
discriminating their anticlimbing activity from the remaining
members of the series. The propensity for fluorine to exhibit
hydrogen-bond acceptor properties is well documented in the
literature, wherein the C(sp2)–F· · ·H–O bond is approximately
one-quarter the strength of a C–O· · ·H–O bond.[13] A further
series of substituents containing a range of hydrogen-bonding
groups would need to be explored in order to support and
strengthen this hypothesis; for example, a prospective variant
Conclusions
A series of substituted 4ꢀ-phenoxypropyl analogues of clozapine
were synthesized and characterized to investigate the biochem-
ical effects of introducing various electron-withdrawing and
electron-donating substituents on the aryl ring of the phe-
noxypropyl moiety. The in vitro receptor binding data revealed
that all target analogues displayed favourable affinity for the
dopamine D4.4 and serotonin 5-HT2A receptors compared with
clozapine and compound 3, with compounds 3b (Y = 3-Cl),

Substituted 4ꢀ-Phenoxypropyl Analogues of the Atypical Antipsychotic Clozapine
119
Table 1. Preliminary binding studies
The behavioural results herein have identified two additional
H
unique analogues that may afford potential antipsychotic activ-
ity. These compounds, and others recognized previously, require
further in vivo pharmacological evaluations to elucidate their
propensity to induce significant side-effects such as EPS and
drug-induced agranulocytosis. This information is absolutely
necessary in order to confirm an atypical profile and identify a
potential successor to clozapine that exhibits a clinical advantage
in the treatment of schizophrenia.
N
Cl
N
N
4ꢀ
N
O
3a–i
Experimental
General
Y
Melting points were determined on a Reichert Micromelting
point apparatus and are uncorrected. Elemental analyses of
samples dried under vacuum were carried out by Microana-
lytical Service, Chemistry Department, University of Queens-
land, Brisbane or Chemical and Micro Analytical Services Pty
Ltd, Belmont, Victoria, Australia. IR spectra were recorded on
Bio-Rad FTS 3500GX utilizing Merlin software for solids with
KBr powder as background and on a Hitachi 270-30 infrared
spectrophotometer with NaCl discs for oils, or as a neat com-
poundonaScimitarSeriesVarian800Fourier-transform(FT)-IR
spectrophotometer with a PIKE Technologies MIRacle atten-
uated total reflectance (ATR) accessory. UV-Vis spectra were
recorded as ethanolic solutions on a Pharmacia Biotech Ultra-
spec 2000 UV-VIS spectrometer utilizing Swift II software.
Wavelengths of maximum absorbance (λmax) are quoted with
respective absorptivities (ε). 1H and 13C NMR spectra were
recorded at 300.13 and 75.47 MHz respectively in CDCl3 using
a Brüker Avance DPX 300 spectrometer equipped with a Sili-
Compound
Y
–
Binding affinity
Percentage inhibition (% I) at 10−6 M
Dopamine D4.4
[3H]spiperone
Serotonin 5-HT2A
[3H]ketanserin
Clozapine
3
72
81
80
74
71
74
70
85
84
86
84
1
3
1
3
1
2
1
1
3
1
3
85
83
91
70
67
83
60
85
80
82
81
1
1
3
1
2
4
5
1
5
2
2
H
3a
3b
3c
3d
3e
3f
3g
3h
3i
2-Cl
3-Cl
4-Cl
3-Br
4-Br
3-CH3
4-CH3
4-OCH3
4-F
Determined in duplicate by MDS Pharma Services (Taiwan).
1
con Graphics work station. Chemical shifts (δ) for all H and
13C spectra are reported in parts per million (ppm) using tetram-
ethylsilane (TMS, 0 ppm) and deuterated chloroform (CDCl3,
77.16 ppm[14]) as the reference, respectively, unless otherwise
stated. In reporting spectral data, the following abbreviations
have been used: s, singlet; d, doublet; t, triplet; q, quartet; p,
quintet; m, multiplet; br, broad; app, apparent; J, coupling con-
stant in Hz; C, quaternary carbon; CH, methine carbon; CO,
carbonyl carbon; CH2, methylene carbon; CH3, methyl carbon.
Electrospray ionization (ESI) mass spectra (MS) were deter-
mined in positive ion mode using a Micromass Platform II
mass spectrometer. High-resolution MS were determined using a
Brüker BioApex II FTICR mass spectrometer. TLC was carried
out routinely on silica gel 60F254 precoated plates (0.25 mm,
Merck). Flash column chromatography was carried out using
Merck silica gel 60, 230–400 mesh ASTM. All solvents were
distilled before use. All chemicals used were purchased from
Sigma–Aldrich Pty Ltd.
Table 2. Antagonism of apomorphine-induced climbing in mice
Compounds were tested as their hydrochloride salts at a dose of 10 mg kg−1
ip (intraperitoneal). *Compounds with statistically significant (P < 0.05)
activity
Compound
Climbing indexA
% Inhibition of climbing
Apomorphine
Vehicle
18.2 1.5
0.4 0.4
–
–
Clozapine
3
6.8 2.6*
5.2 3.2*
14.2 3.1
15.8 3.2
13.8 3.4
17.8 1.0
18.4 0.8
12.2 3.0
15.0 2.6
8.4 3.7*
4.3 3.6*
63
71
22
13
24
2
3a
3b
3c
3d
3e
3f
3g
3h
3i
0
33
18
54
76
General Procedure for the Preparation of Substituted
Phenoxypropyl Bromides[15]
A substituted phenol (10 g) was dissolved with stirring in a
solution of sodium hydroxide (1.1 equiv.) in water (10 mL). The
resulting solution was added dropwise to excess refluxing 1,3-
dibromopropane (2 equiv.). The reaction mixture was heated at
reflux for 2–3 h, cooled to room temperature, then extracted
with diethyl ether (3 × 50 mL). The combined organic extracts
were washed with aqueous 0.5 M NaOH (2 × 30 mL), water
(3 × 30 mL), dried over anhydrous sodium sulfate, filtered and
then concentrated under vacuum to yield a liquid. Vacuum dis-
tillation or column chromatography afforded the title compound
as a colourless liquid, unless otherwise indicated.
AValues represent the mean s.e.m. climbing index.
could be the phenolic analogue (Y = 4-OH), which is simply
derived from treatment of the p-methoxy analogue 3h with
boron tribromide. This novel phenolic analogue, in addition
to possessing a hydrogen-bond acceptor atom, also contains a
hydrogen-bond donor atom, which may exhibit greater in vivo
efficacy through reinforced hydrogen-bonding interactions with
the receptors of interest.

120
B. Capuano et al.
The following substituted phenoxypropyl bromides (6a–h)
were prepared in this manner.
3-(4-Methoxyphenoxy)propyl Bromide 6h
Colourless liquid (7.30 g, 36%), bp 128–130◦C/0.5 mmHg
(lit.[23] 126–127◦C/1 mmHg). δH 6.84 (4H, app s, H2ꢀ, H3ꢀ, H5ꢀ,
H6ꢀ), 4.05 (2H, t, J 6, H3), 3.76 (3H, s, OCH3), 3.59 (2H, t, J
6.5, H1), 2.29 (2H, app p, J 6.5, H2). δC 154.2 (C), 153.0 (CH),
115.7 (CH), 114.8 (C), 66.2 (CH2), 55.9 (CH3), 32.6 (CH2), 30.2
(CH2).
3-(2-Chlorophenoxy)propyl Bromide 6a
Pale yellow liquid (11.3 g, 58%), bp 120–125◦C/3.5 mmHg
(lit.[16] 118–120◦C/5 mmHg). δH 7.43 (1H, dd, J 8, 2, H3ꢀ), 7.31
(1H, app td, J 7.5, 2, H5ꢀ), 7.03–6.95 (2H, m, H4ꢀ, H6ꢀ), 4.23
(2H, t, J 6, H3), 3.73 (2H, t, J 6.5, H1), 2.43 (2H, app p, J 6, H2).
δC 154.3 (C), 130.2 (CH), 127.7 (CH), 123.2 (C), 121.7 (CH),
113.7 (CH), 66.5 (CH2), 32.4 (CH2), 30.0 (CH2).
General Procedure for the Preparation of Monosubstituted
Piperazines[1]
To a solution of a substituted phenoxypropyl bromide (6a–h), or
commercially available 3-(4-fluorophenoxy)propyl chloride (6i)
(1 equiv.), in toluene was added anhydrous piperazine (4 equiv.).
The solution was heated at 85◦C for 2 h, unless otherwise stated,
after which it was cooled, filtered and the filtrate evaporated
to dryness under vacuum. The resulting residue was then par-
titioned between aqueous hydrochloric acid (2 M, 50 mL) and
dichloromethane (50 mL) and the aqueous phase washed with
dichloromethane (2 × 50 mL). The aqueous phase was adjusted
to pH 14 with solid sodium hydroxide, then extracted with
dichloromethane (3 × 100 mL).The organic fractions were com-
bined, washed with water (2 × 50 mL), brine (50 mL), dried over
anhydrous sodium sulfate, filtered and then concentrated under
vacuum to yield an oil. Vacuum distillation or flash column
chromatography afforded the title compound as a liquid, unless
otherwise indicated.
3-(3-Chlorophenoxy)propyl Bromide[17] 6b
Pale yellow liquid (11.1 g, 57%), bp 115–118◦C/3 mmHg. δH
7.21 (1H, app t, J 8, H5ꢀ), 6.92–6.98 (2H, m, H2ꢀ, H4ꢀ), 6.81
(1H, m, H6ꢀ), 4.10 (2H, t, J 6, H3), 3.60 (2H, t, J 6.5, H1), 2.33
(2H, app p, J 6, H2). δC 159.6 (C), 135.1 (C), 130.4 (CH), 121.3
(CH), 115.2 (CH), 113.2 (CH), 65.8 (CH2), 32.4 (CH2), 29.9
(CH2).
3-(4-Chlorophenoxy)propyl Bromide 6c
Pale yellow liquid (11.0 g, 57%), bp 135–138◦C/0.4 mmHg
(lit.[18] 108–110◦C/0.2 mmHg; lit.[15] 128–134◦C/0.2 mmHg).
δH 7.22 (2H, d, J 7.5, H3ꢀ, H5ꢀ), 6.82 (1H, d, J 7.5, H2ꢀ, H6ꢀ),
4.08 (2H, t, J 6, H1), 3.58 (2H, t, J 6.5, H3), 2.30 (2H, p, J 6, H2).
δC 157.5 (C), 129.5 (CH), 126.0 (C), 116.0 (CH), 65.9 (CH2),
32.5 (CH2), 30.0 (CH2).
The following monosubstituted piperazines (8a–i) were pre-
pared in this manner.
1-(3-(2-Chlorophenoxy)propyl)piperazine 8a
3-(3-Bromophenoxy)propyl Bromide[19] 6d
A solution of 3-(2-chlorophenoxy)propyl bromide (6a, 7.55 g,
30.2 mmol) in toluene (150 mL) reacted with piperazine (10.8 g,
125 mmol), and after workup afforded a yellow liquid (2.83 g,
37%). Bp 170–178◦C/1.4 mmHg (lit.[24] 174–175◦C/2 mmHg).
δH 7.34 (1H, dd, J 8, 1.5, H3ꢀꢀ), 7.18 (1H, app td, J 7.5, 1.5, H5ꢀꢀ),
6.94–6.83 (2H, m, H4ꢀꢀ, H6ꢀꢀ), 4.08 (2H, t, J 6.5, H3ꢀ), 2.89 (4H,
m, H3, H5), 2.54 (2H, t, J 7.5, H1ꢀ), 2.48 (4H, m, H2, H6), 2.00
(2H, app p, J 6.5, H2ꢀ), 1.72 (1H, s, H4). δC 154.6 (C), 129.9
(CH), 127.6 (CH), 123 (C), 121.3 (CH), 113.6 (CH), 67.4 (CH2),
55.2 (CH2), 54.6 (CH2), 46.1 (CH2), 26.4 (CH2).
Yellow liquid (11.0 g, 62%), bp 124–126◦C/0.9 mmHg. δH 7.16–
7.05 (3H, m, H2ꢀ, H4ꢀ, H5ꢀ), 6.83 (1H, d app t, J 6, 2, H6ꢀ), 4.08
(2H, t, J 5.5, H3), 3.58 (2H, t, J 6.5, H1), 2.30 (2H, app p, J
6, H2). δC 159.5 (C), 130.6 (CH), 124.0 (CH), 122.9 (C), 118.1
(CH), 113.8 (CH), 65.8 (CH2), 32.3 (CH2), 29.8 (CH2).
3-(4-Bromophenoxy)propyl Bromide 6e
Pale yellow liquid (11.2 g, 66%), bp 118–124◦C/0.7 mmHg
(lit.[20] 169◦C/12 mmHg). δH 7.37 (2H, d, J 9, H3ꢀ, H5ꢀ), 6.78
(2H, d, J 9, H2ꢀ, H6ꢀ), 4.06 (2H, t, J 5.5, H3), 3.58 (2H, t, J 6.5,
H1), 2.30 (2H, app p, J 6, H2). δC 158.0 (C), 132.5 (CH), 118.0
(C), 116.5 (CH), 65.2 (CH2), 32.4 (CH2), 30.0 (CH2).
1-(3-(3-Chlorophenoxy)propyl)piperazine 8b
A solution of 3-(3-chlorophenoxy)propyl bromide (6b, 8.00 g,
32.6 mmol) in toluene (200 mL) reacted with piperazine (11.2 g,
130 mmol) and after workup afforded a bright yellow liquid
(4.37 g, 53%). Bp 181–184◦C/40 mmHg. δH 7.11–7.16 (1H, m,
H5ꢀꢀ), 6.86–6.89 (2H, m, H2ꢀꢀ, H4ꢀꢀ), 6.73–6.76 (1H, m, H6ꢀꢀ),
3.96 (2H, t, J 6.5, H3ꢀ), 2.86 (4H, m, H3, H5), 2.45 (2H, t, J 7,
H1ꢀ), 2.39 (4H, m, H2, H6), 1.92 (2H, app p, H2ꢀ), 1.69 (1H, s,
H4). δC 159.9 (C), 130.2 (CH), 120.2 (CH), 115.0 (CH), 113.2
(CH), 66.6 (CH2), 55.7 (CH2), 54.7 (CH2), 46.2 (CH2), 26.6
(CH2).
3-(3-Methylphenoxy)propyl Bromide 6f
Colourless liquid (11.0 g, 52%), bp 100–102◦C/1.5 mmHg
(lit.[21] 144–148◦C/10 mmHg). δH 7.22 (1H, app t, J 7.5, H5ꢀ),
6.84–6.75 (3H, m, H2ꢀ, H4ꢀ, H6ꢀ), 4.13 (2H, t, J 6, H3), 3.64
(2H, t, J 6.5, H1), 2.38 (3H, s, CH3), 2.33 (2H, app p, J 6.5, H2).
δC 158.9 (C), 139.7 (C), 129.4 (CH), 115.6 (CH), 65.4 (CH2),
32.7 (CH2), 30.2 (CH2), 21.7 (CH3).
1-(3-(4-Chlorophenoxy)propyl)piperazine 8c
A solution of 3-(4-chlorophenoxy)propyl bromide (6c, 5.04 g,
20.2 mmol) in toluene (100 mL) reacted with piperazine
(7.02 g, 81.5 mmol) and after workup afforded a pale yel-
low liquid (3.45 g, 67%). Bp 170–174◦C/0.4 mmHg (lit.[25]
158◦C/0.2 mmHg). δH 7.17 (2H, d, J 9, H3ꢀꢀ, H5ꢀꢀ), 6.78 (2H,
d, J 9, H2ꢀꢀ, H6ꢀꢀ), 3.94 (2H, t, J 6.5, H3ꢀ), 2.85 (4H, m, H3, H5),
2.45 (2H, t, J 7.5, H1ꢀ), 2.40 (4H, m, H2, H6), 1.91 (2H, app p,
J 7, H2ꢀ), 1.57 (1H, s, H4). δC 157.6 (C), 129.1 (CH2), 124 (C),
3-(4-Methylphenoxy)propyl Bromide 6g
Colourless liquid (8.45 g, 40%), bp 112–114◦C/0.2 mmHg
(lit.[22] 155–160◦C/21 mmHg). δH 7.07 (2H, d, J 8.5, H3ꢀ, H5ꢀ),
6.79 (2H, d, J 8.5, H2ꢀ, H6ꢀ), 4.05 (2H, t, J 6, H3), 3.58 (2H,
t, J 6.5, H1), 2.29 (2H, app p, J 6, H2), 2.28 (1H, s, CH3). δC
156.7 (C), 130.3 (C), 130.1 (CH), 114.6 (CH), 65.6 (CH2), 32.6
(CH2), 30.2 (CH2), 20.6 (CH3).

Substituted 4ꢀ-Phenoxypropyl Analogues of the Atypical Antipsychotic Clozapine
121
115.7 (CH2), 66.5 (CH2), 55.5 (CH2), 54.6 (CH2), 46.0 (CH2),
26.4 (CH2).
(CH), 67.1 (CH2), 56.0 (CH2), 55.9 (CH3), 54.7 (CH2), 46.2
(CH2), 26.8 (CH2).
1-(3-(4-Fluorophenoxy)propyl)piperazine[28] 8i
1-(3-(3-Bromophenoxy)propyl)piperazine 8d
A solution of 1-(3-chloropropoxy)-4-fluorobenzene (6i, 10.0 g,
53.0 mmol) in toluene (250 mL) reacted with piperazine (18.3 g,
212 mmol) and after workup afforded a pale yellow liquid,
(8.01 g, 63%). Bp 175–176◦C/0.9 mmHg. δH 6.95 (2H, app t,
J 8.5, H3ꢀꢀ, H5ꢀꢀ), 6.82 (2H, dd, J 8.5, 4.5, H2ꢀꢀ, H6ꢀꢀ), 3.94 (2H,
t, J 6.5, H3ꢀ), 2.87 (4H, m, H3, H5), 2.47 (2H, t, J 7.5, H1ꢀ), 2.41
(4H, m, H2, H6), 1.93 (2H, app p, J 6.5, H2ꢀ), 1.63 (1H, s, H4).
δC 156.4 (d, J 261, CF), 154.9 (C), 115.1 (d, J 23, C), 114.9 (d,
J 8, C), 66.3 (CH2), 55.2 (CH2), 54.1 (CH2), 45.6 (CH2), 26.0
(CH2).
A solution of 3-(3-bromophenoxy)propyl bromide (6d, 7.56 g,
25.7 mmol) in toluene (150 mL) reacted with piperazine (9.22 g,
107 mmol) and after workup and flash column chromatography
(90:9:1, dichloromethane/methanol/25% w/v aqueous ammo-
nia) afforded a pale yellow liquid (6.86 g, 89%). δH 7.12 (1H,
app t, J 8.5, H5ꢀꢀ), 7.08–7.03 (2H, m, H2ꢀꢀ, H4ꢀꢀ), 6.82 (1H, ddd,
J 8, 2.5, 1, H6ꢀꢀ), 3.99 (2H, t, J 6.5, H3ꢀ), 2.90 (4H, m, H3, H5),
2.49 (2H, t, J 7.5, H1ꢀ), 2.44 (4H, m, H2, H6), 1.96 (1H, s, H4),
1.94 (2H, app p, J 7, H2ꢀ). δC 159.5 (C), 130.2 (CH), 123.3 (CH),
122.4 (C), 117.4 (CH), 113.2 (CH), 66.1 (CH2), 55.4 (CH2), 54.3
(CH2), 45.8 (CH2), 26.1 (CH2).
General Procedure for the Preparation of the Tricyclic
Amidines (3a–i)
1-(3-(4-Bromophenoxy)propyl)piperazine[26] 8e
To a solution of the monosubstituted piperazine (8a–i)[1,29]
(5.10 mmol, 5 equiv.) in anhydrousanisole (5 mL) under nitrogen
was added a solution of titanium tetrachloride in toluene (1.0 M,
1.12 mL, 1.12 mmol, 1.1 equiv.). The mixture was warmed
to 50◦C and a hot solution of 8-chloro-10,11-dihydro-5H-
dibenzo[b,e][1,4]diazepine-11-one (9) (250 mg, 1.02 mmol) in
anhydrous anisole (15 mL) was then added. The mixture was
heated at reflux for 4 h, after which time it was cooled and
then evaporated to dryness under vacuum. The brown-coloured
residue was partitioned between ethyl acetate (50 mL) and aque-
ous sodium hydroxide (2 M, 30 mL), the mixture filtered under
vacuum and the residue washed with ethyl acetate (20 mL). The
organic layer was separated and the aqueous phase extracted
with ethyl acetate (2 × 50 mL). The organic fractions were com-
bined, washed with water (2 × 30 mL), dried (anhydrous sodium
sulfate), evaporated to dryness and the resulting oily residue
purified using flash column chromatography. The major product
fractions were evaporated to dryness, and where appropriate, the
residual solid recrystallized from a suitable solvent system.
The following compounds were prepared in this manner.
A solution of 3-(4-bromophenoxy)propyl bromide (6e, 5.0 g,
17.0 mmol) in toluene (100 mL) reacted with piperazine (5.86 g,
68.0 mmol) and after workup and flash column chromatography
(90:9:1, dichloromethane/methanol/25% w/v aqueous ammo-
nia) afforded a colourless liquid (4.03 g, 52%). δH 7.33 (2H,
d, J 7, H3ꢀꢀ, H5ꢀꢀ), 6.78 (2H, d, J 9, H2ꢀꢀ, H6ꢀꢀ), 3.96 (2H, t, J
6.5, H3ꢀ), 2.88 (4H, m, H3, H5), 2.47 (2H, t, J 7.5, H1ꢀ), 2.42
(4H, m, H2, H6), 1.93 (3H, app p, J 7, H2ꢀ), 1.72 (1H, s, H4).
δC 158.3 (C), 132.3 (CH), 116.5 (CH), 112.8 (C), 66.7 (CH2),
55.8 (CH2), 54.7 (CH2), 46.2 (CH2), 26.6 (CH2).
1-(3-(3-Methylphenoxy)propyl)piperazine 8f
A solution of 3-(3-methylphenoxy)propyl bromide (6f, 8.00 g,
34.9 mmol) in toluene (200 mL) reacted with piperazine (12.0 g,
140 mmol) and after workup afforded a pale yellow liquid
(2.73 g, 33%). Bp 180–184◦C/0.5 mmHg. δH 7.12 (1H, app t,
J 7.5, H5ꢀꢀ), 6.74–6.67 (3H, m, H2ꢀꢀ, H4ꢀꢀ, H6ꢀꢀ), 3.97 (2H, t, J
6.5, H3ꢀ), 2.87 (4H, m, H3, H5), 2.47 (2H, t, J 7.5, H1ꢀ), 2.40
(4H, m, H2, H6), 2.30 (3H, s, CH3), 1.93 (2H, app p, J 6.5, H2ꢀ),
1.64 (1H, s, H4). δC 159.1 (C), 139.4 (CH), 129.2 (C), 121.4
(CH), 115.4 (CH), 111.5 (CH), 66.2 (CH2), 55.9 (CH2), 54.7
(CH2), 46.2 (CH2), 26.7 (CH2), 21.6 (CH3).
8-Chloro-11-(4-(3-(2-chlorophenoxy)propyl)piperazin-
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3a
Purified by flash chromatography (4:1 ethyl acetate/hexane),
1-(3-(4-Methylphenoxy)propyl)piperazine[27] 8g
yellow foam, yield 66% (Found:
11.9. C26H26Cl2N4O requires C 64.8, H 5.4, N 11.7%.)
νmax(FTIR)/cm−1 3298, 1598, 1555. λmax/nm (ε/M−1 cm−1
C 64.5, H 5.6, N
A solution of 3-(4-methylphenoxy)propyl bromide (6g, 8.02 g,
35.0 mmol) in toluene (100 mL) reacted with piperazine (12.0 g,
140 mmol) and after workup afforded a pale yellow liquid
(5.35 g, 66%). Bp 177–180◦C/0.5 mmHg. δH 7.05 (2H, d, J 8.5,
H3ꢀꢀ, H5ꢀꢀ), 6.78 (2H, d, J 8.5, H2ꢀꢀ, H6ꢀꢀ), 3.96 (2H, t, J 6.5,
H3ꢀ), 2.87 (4H, m, H3, H5), 2.41–2.50 (6H, m, H1ꢀ, H2, H6),
2.26 (3H, s, CH3), 1.94 (2H, app p, J 6.5, H2ꢀ), 1.75 (1H, s, H4).
δC 156.9 (C), 129.8 (CH), 129.7 (C), 114.4 (CH), 66.4 (CH2),
55.8 (CH2), 54.7 (CH2), 46.2 (CH2), 26.7 (CH2), 20.4 (CH3).
)
229 (41500), 262 (18400), 291 (12300). δH 7.35–7.06 (4H, m,
H1, H3, H3ꢀꢀꢀ, H5ꢀꢀꢀ), 7.01–6.78 (6H, m, H2, H4, H6, H9, H4ꢀꢀꢀ,
H6ꢀꢀꢀ), 6.59 (1H, d, J 8, H7), 5.00 (1H, s, H5), 4.10 (2H, t, J 6.5,
H3ꢀꢀ), 3.46 (4H, m, H2ꢀ, H6ꢀ), 2.61 (2H, t, J 7, H1ꢀꢀ), 2.55 (4H, m,
H3ꢀ, H5ꢀꢀ), 2.02 (2H, app p, J 6.5, H2ꢀꢀ). δC 162.8 (C), 154.6 (C),
152.9 (C), 141.9 (C), 140.6 (C), 131.9 (CH), 130.3 (CH), 129.0
(C), 127.8 (CH), 126.8 (CH), 123.5 (C), 123.1 (CH), 121.4 (CH),
120.0 (CH), 113.6 (CH), 67.3 (CH2), 55.0 (CH2), 53.2 (CH2),
47.3 (CH2), 26.6 (CH2). m/z (ESI 20V) 485.2 (M[37Cl2]H+,
12%), 483.3 (M[37Cl,35Cl]H+, 66%), 481.2 (M[35Cl2]H+, 100).
1-(3-(4-Methoxyphenoxy)propyl)piperazine[25] 8h
A solution of 3-(4-methoxyphenoxy)propyl bromide (6h,
5.11 g, 0.02 mol) in toluene (100 mL) reacted with piperazine
(7.17 g, 0.08 mol) and after flash column chromatography
(90:9:1, dichloromethane/methanol/25% w/v aqueous ammo-
nia) afforded a pale yellow liquid (2.68 g, 52%). δH 6.81 (4H,
br s, H2ꢀꢀ, H3ꢀꢀ, H5ꢀꢀ, H6ꢀꢀ), 3.94 (2H, t, J 6.5, H3ꢀ), 3.74 (3H, s,
H2ꢀꢀꢀ), 2.87 (4H, m, H3, H5), 2.46 (6H, m, H1ꢀ, H2, H6), 1.95
(3H, m, H2ꢀ, H4). δC 153.9 (C), 153.4 (C), 115.7 (CH), 114.8
8-Chloro-11-(4-(3-(3-chlorophenoxy)propyl)piperazin-
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3b
Purifiedbyflashchromatography(1:1ethylacetate/hexane), yel-
low microprisms (acetone/hexane), yield 63%. Mp 106.5–107◦C
(Found: C 64.8, H 5.4, N 11.8. C26H26Cl2N4O requires C 64.8,
H 5.4, N 11.7%.) νmax(FTIR)/cm−1 3296, 1596, 1557. λmax/nm

122
B. Capuano et al.
(ε/M−1 cm−1) 262 (19100), 297 (11700). δH (acetone[D6])
7.36–7.25 (3H, m, H1, H3, H5ꢀꢀꢀ), 7.08–6.98 (2H, m, H4, H2),
6.98–6.79 (6H, m, H6, H7, H9, H2ꢀꢀꢀ, H4ꢀꢀꢀ, H6ꢀꢀꢀ), 6.52 (1H,
s, H5), 4.11 (2H, t, J 6.5, H3ꢀꢀ), 3.42 (4H, m, H2ꢀ, H6ꢀ), 2.55
(2H, t, J 7, H1ꢀꢀ), 2.52 (4H, m, H3ꢀ, H5ꢀ), 1.97 (2H, app p, J
6.5, H2ꢀꢀ). δC 164.0 (C), 161.2 (C), 155.0 (C), 143.5 (C), 142.9
(C), 135.3 (C), 132.8 (CH), 131.5 (CH), 131.0 (CH), 128.6
(C), 127.0 (CH), 124.7 (C), 123.5 (CH), 123.4 (CH), 121.4
(CH), 121.3 (CH), 121.2 (CH), 115.6 (CH), 114.3 (CH), 67.3
(CH2), 55.5 (CH2), 53.9 (CH2), 48.3 (CH2), 27.5 (CH2). m/z
(ESI 20V) 485.2 (M[37Cl2]H+, 11%), 483.3 (M[37Cl,35Cl]H+,
65%), 481.2 (M[35Cl2]H+, 100).
H3ꢀꢀ), 3.42 (4H, m, H2ꢀ, H6ꢀ), 2.61–2.49 (6H, m, H3ꢀ, H5ꢀ, H1ꢀꢀ),
1.97 (2H, app p, J 6.5, H2ꢀꢀ). δC (acetone[D6]) 163.6 (C), 159.2
(C), 155.2 (C), 143.1 (C), 142.5 (C), 133.0 (CH), 132.8 (CH),
131.0 (CH), 128.3 (C), 126.9 (CH), 124.4 (C), 123.42 (CH),
123.36 (CH), 121.3 (CH), 121.1 (CH), 117.5 (CH), 112.5 (C),
67.2(CH2), 55.5(CH2), 53.8(CH2), 48.3(CH2), 27.4(CH2). m/z
(ESI 20V) 529.5 (M[81Br,37Cl]H+, 26%) 527.3 (M[79Br,37Cl
or 81Br,35Cl]H+, 100), 525.3 (M[79Br,35Cl]H+, 86). ESI high-
resolution MS: found m/z 525.1063 (MH+). Calculated for
C26H2779Br35ClN4O: m/z 525.1057.
8-Chloro-11-(4-(3-(3-methylphenoxy)propyl)piperazin-
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3f
8-Chloro-11-(4-(3-(4-chlorophenoxy)propyl)piperazin-
Purified by flash chromatography (4:3 ethyl acetate/hexane),
yellow microneedles (dichloromethane/hexane), yield 76%. Mp
112.5–113◦C (Found: C 70.0, H 6.7, N 11.8. C27H29ClN4O
requires: C 70.3, H 6.3, N 12.2%.) νmax(FTIR)/cm−1 3294,
1597, 1556. λmax/nm (ε/M−1 cm−1) 262 (18600), 297 (11500).
δH (acetone[D6]) 7.36–7.29 (2H, m, H1, H3), 7.13 (1H, app t,
J 7.5, H5ꢀꢀꢀ), 7.08–6.70 (2H, m, H2, H4), 6.95 (1H, d, J 2.5,
H9), 6.88 (1H, d, J 8.5, H6), 6.81 (1H, dd, J 8.5, 2.5, H7), 6.75–
6.71 (3H, m, H2ꢀꢀꢀ, H4ꢀꢀꢀ, H6ꢀꢀꢀ), 6.52 (1H, s, H5), 4.05 (2H, t,
J 6.5, H3ꢀꢀ), 3.42 (4H, m, H2ꢀ, H6ꢀ), 2.57–2.52 (6H, m, H3ꢀ,
H5ꢀ, H1ꢀꢀ), 2.28 (3H, s, CH3), 1.95 (2H, app p, J 6.5, H2ꢀꢀ). δC
(acetone[D6]) 164.1 (C), 160.3 (C), 155.0 (C), 143.5 (C), 142.9
(C), 140.1 (C), 132.8 (CH), 131.0 (CH), 130.1 (CH), 128.6 (C),
127.0 (CH), 124.7 (C), 123.5 (CH), 123.4 (CH), 122.1 (CH),
121.4 (CH), 121.2 (CH), 116.2 (CH), 112.4 (CH), 66.7 (CH2),
55.7 (CH2), 54.0 (CH2), 48.4 (CH2), 27.7 (CH2), 21.6 (CH3).
m/z (ESI 20V) 463.3 (M[37Cl]H+, 35%), 461.3 (M[35Cl]H+,
100), 459.3 (20). ESI high-resolution MS: found m/z 461.2118
(MH+). Calculated for C27H3035ClN4O: m/z 461.2108.
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3c
Purified by flash chromatography (4:1 ethyl acetate/hexane),
yellow prisms (methanol/water), yield 47%. Mp 172–173◦C
(Found: C 64.9, H 5.5, N 11.6. C26H26Cl2N4O requires: C
64.9, H 5.4, N 11.6%.) νmax (FTIR)/cm−1 3362, 1594, 1558.
λmax/nm (ε/M−1 cm−1) 229 (40700), 261 (18200), 290 (12600).
δH (acetone[D6]) 7.38–7.24 (4H, m, H1, H3, H3ꢀꢀꢀ, H5ꢀꢀꢀ), 7.10–
6.78 (7H, m, H2, H4, H6, H7, H9, H2ꢀꢀꢀ, H6ꢀꢀꢀ), 6.52 (1H, s,
H5), 4.08 (2H, t, J 6.5, H3ꢀꢀ), 3.42 (4H, m, H2ꢀ, H6ꢀ), 2.49–
2.59 (6H, m, H3ꢀ, H5ꢀ, H1ꢀꢀ), 1.96 (2H, app p, J 6.5, H2ꢀꢀ).
δC (acetone[D6]) 163.1 (C), 158.1 (C), 154.1 (C), 142.5 (C),
142.0 (C), 131.9 (CH), 130.1 (CH), 129.2 (CH), 127.6 (C), 126.0
(CH), 124.7 (C), 123.7 (C), 122.5 (CH), 122.4 (CH), 120.4 (CH),
120.3 (CH), 120.2 (CH), 120.1 (CH), 116.1 (CH), 66.3 (CH2),
54.6 (CH2), 52.9 (CH2), 47.4 (CH2), 26.5 (CH2). m/z (ESI 20V)
483.2 (M[37Cl2]H+, 62%), 481.2 (M[37Cl,35Cl]H+, 100), 479.2
(M[35Cl2]H+, 19).
8-Chloro-11-(4-(3-(3-bromophenoxy)propyl)piperazin-
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3d
8-Chloro-11-(4-(3-(4-methylphenoxy)propyl)piperazin-
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3g
Purified by flash chromatography (4:1 ethyl acetate/hexane),
yellow foam, yield 36% (Found:
C
59.5,
H
5.1,
N
Purified by flash chromatography (4:1 ethyl acetate/hexane),
yellow prisms (methanol/water), yield 53%. Mp 154.5–156.5◦C
(Found: C 70.4, H 6.4, N 12.2. C27H29ClN4O requires: C 70.3, H
6.3, N 12.2%.) νmax(KBr)/cm−1 3292, 2920, 2852, 1598, 1558.
λmax/nm (ε/M−1 cm−1) 225 (35500), 261 (18200), 297 (12000).
δH (acetone[D6]) 7.36–7.26 (m, 2H, H1, H3), 7.08–6.99 (m, 4H,
H2, H4, H3ꢀꢀꢀ, H5ꢀꢀꢀ), 6.96 (m, 1H, H9), 6.88–6.75 (m, 4H, H6,
H7, H2ꢀꢀꢀ, H6ꢀꢀꢀ), 6.52 (s, 1 H, H5), 4.02 (t, J 6.5, 2H, H3ꢀꢀ), 3.41
(m, 4H, H2ꢀ, H6ꢀ), 2.60–2.50 (m, 6H, H1ꢀꢀ, H3ꢀ, H5ꢀ), 2.23 (s, 3H,
CH3), 1.93 (2H, app p, J 6.5, H2ꢀꢀ). δC (acetone[D6]) 164.0 (C),
158.1 (C), 154.9 (C), 143.4 (C), 142.9 (C), 132.7 (CH), 130.9
(CH), 130.6 (CH), 130.1 (C), 128.5 (C), 126.9 (CH), 124.6 (C),
123.40 (CH), 123.35 (CH), 121.3 (CH), 121.1 (CH), 115.2 (CH),
66.8 (CH2), 55.7 (CH2), 53.8 (CH2), 48.2 (CH2), 27.6 (CH2),
20.5 (CH3). m/z (ESI 20V) 463.3 (M[37Cl]H+, 36%), 461.3
(M[35Cl]H+, 100).
10.4. C26H26BrClN4O requires: C 59.4, H 5.0, N 10.7%.)
νmax(FTIR)/cm−1 3355, 1598, 1556. λmax/nm (log10 ε) 229
(41800), 263 (18900), 292 (12600). δH (acetone[D6]) 7.35–7.28
(2H, m, H1, H3), 7.21 (1H, app td, J 8, 2, H5ꢀꢀꢀ), 7.08–6.92 (6H,
m, H2, H4, H9, H2ꢀꢀꢀ, H4ꢀꢀꢀ, H6ꢀꢀꢀ), 6.88 (1H, d, J 8, H6), 6.80
(1H, dd, J 8.5, 2.5, H7), 6.51 (1H, s, H5), 4.09 (2H, t, J 6, H3ꢀꢀ),
3.42 (4H, m, H2ꢀ, H6ꢀ), 2.62–2.46 (6H, m, H3ꢀ, H5ꢀ, H1ꢀꢀ), 1.95
(2H, app p, J 6.5, H2ꢀꢀ). δC (acetone[D6]) 163.1 (C), 160.3 (C),
154.1 (C), 142.5 (C), 142.0 (C), 131.9 (CH), 130.9 (CH), 130.1
(CH), 127.6 (C), 126.1 (CH), 123.7 (C), 123.4 (CH), 122.5 (CH),
122.4 (C), 120.4 (CH), 117.6 (CH), 113.8 (CH), 66.3 (CH2), 54.5
(CH2), 52.9(CH2), 47.4(CH2), 26.5(CH2). m/z (ESI20V)529.5
(M[81Br,37Cl]H+, 26%), 527.3 (M[79Br,37Cl or 81Br,35Cl]H+,
100), 525.3 (M[79Br,35Cl]H+, 83).
8-Chloro-11-(4-(3-(4-bromophenoxy)propyl)piperazin-
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3e
8-Chloro-11-(4-(3-(4-methoxyphenoxy)propyl)piperazin-
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3h
Purifiedbyflashchromatography(4:1ethylacetate/hexane), yel-
low microprisms (methanol/water), yield 70%. Mp 160–161◦C
(Found:C57.7, H5.8, N9.8. C26H26BrClN4O·CH3OHrequires:
C 58.1, H 5.4, N 10.0%.) νmax(FTIR)/cm−1 3364, 1595, 1557.
λmax/nm (ε/M−1 cm−1) 229 (42700), 261 (19100), 291 (12900).
δH (acetone[D6]) 7.45–7.38 (2H, m, H1, H3), 7.26–7.37 (2H,
m, H3ꢀꢀꢀ, H5ꢀꢀꢀ), 7.11–6.98 (2H, m, H2ꢀꢀꢀ, H6ꢀꢀꢀ), 6.97–6.78 (5H,
m, H2, H4, H6, H7, H9), 6.52 (1H, s, H5), 4.09 (2H, t, J 6.5,
Purified by flash chromatography (4:1 ethyl acetate/hexane),
yellow prisms (methanol/water), yield 40%. Mp 157.5–158◦C
(Found: C 68.4, H 6.5, N 11.6. C27H29ClN4O2 requires: C
68.0, H 6.1, N 11.8%.) νmax(FTIR)/cm−1 3358, 1595, 1552.
λmax/nm (ε/M−1 cm−1) 227 (38000), 261 (18600), 294 (14100).
δH (acetone[D6]) 7.37–7.27 (2H, m, H1, H3), 7.10–6.98 (2H, m,
H2, H4), 6.94 (1H, d, J 2.5, H9), 6.77–6.90 (6H, m, H6, H7, H3ꢀꢀꢀ,

Substituted 4ꢀ-Phenoxypropyl Analogues of the Atypical Antipsychotic Clozapine
123
H4ꢀꢀꢀ, H5ꢀꢀꢀ, H6ꢀꢀꢀ), 6.52 (1H, s, H5), 4.01 (2H, t, J 6.5, H3ꢀꢀ), 3.73
(3H, s, OCH3), 3.42 (4H, m, H2ꢀ, H6ꢀ), 2.54 (6H, m, H3ꢀ, H5ꢀ,
H1ꢀꢀ), 1.93 (2H, app p, J 6.5, H2ꢀꢀ). δC (acetone[D6]) 163.1 (C),
154.1(C), 153.9(C), 153.3(C), 142.5(C), 142.0(C), 131.9(CH),
130.0 (CH), 127.6 (C), 126.0 (CH), 123.7 (C), 122.5 (CH), 122.5
(CH), 120.4 (CH), 120.2 (CH), 120.1 (CH), 115.4 (CH), 114.5
(CH), 66.4 (CH2), 55.0 (CH3), 54.8 (CH2), 53.0 (CH2), 47.4
(CH2), 26.8 (CH2). m/z (ESI 20V) 479.2 (M[37Cl]H+, 33%),
477.3 (MH+, 100). ESI high-resolution MS: found m/z 477.209
(M[35Cl]H+). Calculated for C27H3035ClN4O2: m/z 477.206.
were pretreated with test compound (10 mg kg−1 ip; 0.1 mL
per 10 g bodyweight) 30 min before an injection of apomor-
phine hydrochloride (3 mg kg−1 ip). Climbing behaviour was
assessed[30] at 5-min intervals over a period of 25 min commenc-
ing 5 min after apomorphine administration, using the following
scoring system: 0 – no paws on the cage, 1 – one paw on the cage,
2 – two paws on the cage, 3 – three paws on the cage, 4 – four
paws on the cage. The score recorded for each animal was based
on the number of paws on the cage at a particular time point, at
the moment the animal was first observed. The mean climbing
score (m.c.s.) was calculated by summation of the total score
per mouse for all mice per dose over the course of the experi-
ment, and dividing that figure by the number of mice per dose.
The results of the experiment were expressed as a mean value
8-Chloro-11-(4-(3-(4-fluorophenoxy)propyl)piperazin-
1-yl)-5H-dibenzo[b,e][1,4]diazepine 3i
per mouse s.e.m (standard error of mean calculated by s/√
,
Purified by flash chromatography (4:1 ethyl acetate/hexane),
yellow microprisms (methanol/water), yield 32%. Mp 172–
174◦C (Found: C 65.0, H 6.1, N 11.2. C26H26ClFN4O·CH3OH
requires:C65.3, H6.1, N11.3%.) νmax(FTIR)/cm−1 3359, 1595,
1558. λmax/nm (ε/M−1 cm−1) 269 (17800), 298 (12500). δH
(acetone[D6]) 7.38–7.27 (2H, m, H1, H3), 7.11–6.77 (9H, m,
H2, H4, H6, H7, H9, H2ꢀꢀꢀ, H3ꢀꢀꢀ, H5ꢀꢀꢀ, H6ꢀꢀꢀ), 6.52 (1H, s, H5),
4.06 (2H, t, J 6.5, H3ꢀꢀ), 3.42 (4H, m, H2ꢀ, H6ꢀ), 2.55 (6H, m,
H3ꢀ, H5ꢀ, H1ꢀꢀ), 1.96 (2H, app p, J 6.5, H2ꢀꢀ). δC (acetone[D6])
and δC (acetone[D6]) 162.9 (C), 157.3 (d, J 238, CF), 155.2 (C),
152.8 (C), 141.9 (C), 140.5 (C), 132.0 (CH), 130.4 (CH), 129.1
(C), 126.8 (CH), 123.5 (C), 123.19 (CH), 123.16 (CH), 120.2
(CH), 120.1 (CH), 115.9 (d, J 23, C), 115.5 (d, J 8, C), 66.8
(CH2), 55.2 (CH2), 53.2 (CH2), 47.3 (CH2), 26.7 (CH2). m/z
(ESI 20V) 467.3 (M[37Cl]H+, 33%), 465.3 (M[35Cl]H+, 100),
463.3 (20).
n
where s is the sample standard deviation and n is the sample size).
The value of percentage inhibition of climbing was calculated
using the following formula.
% Inhibition climbing
[m.c.s. (apomorphine) − m.c.s. (drug)]
=
× 100
m.c.s. (apomorphine)
Statistical Analysis
The statistical analysis was carried out by one-way analysis of
variance (ANOVA) followed by Dunnett’s test for pair-wise com-
parison of drug-treated groups and apomorphine-treated control,
using GraphPad Prism version 4.00 for Windows (GraphPad
Software, SanDiego, CA, USA), with P < 0.05beingconsidered
as statistically significant.
Pharmacology Procedures
Receptor Binding Assays
Acknowledgement
The authors gratefully acknowledge the contributions to this paper by Bach-
elor of Medicinal Chemistry (Monash University) undergraduate students
(Theola Louie, Andrew Lin, Tam Nguyen, Victoria Oliver, and Sean Lim)
and sincerely thank Dr Simon Egan and Mr Stuart Thomson for NMR and
mass spectra of compounds described.
Receptor affinities were determined by MDS Pharma Ser-
vices (Taiwan), by the ability of the tested compounds to
displaceselectiveradioligands.Allassayedcompoundsweredis-
solved in dimethylsulfoxide (DMSO) to a stock concentration of
10−2 M, then diluted with assay buffer to a final concentration
of 10−6 M. The assays were carried out using the following:
(i) for dopamine D4.4 receptors: human recombinant (expressed
in mammalian CHO-K1 cells), [3H]spiperone (0.3 nM) as radio-
ligand, and haloperidol (10 µM) as reference compound for
non-specific binding; (ii) for serotonin 5-HT2A receptors: rat
cortex, [3H]ketanserin (0.5 nM) as radioligand, and ketanserin
(1 µM) as reference compound for non-specific binding. The
binding resultsareexpressed as thepercentage inhibition (% I) of
specific binding at a concentration of 10−6 M for the tested com-
pound and represent the mean of duplicate tubes the maximum
standard error in the mean.
References
[1] B. Capuano, I.T. Crosby, E. J. Lloyd, D.A.Taylor,Aust. J. Chem. 2002,
55, 565. doi:10.1071/CH02093
[2] J. Kane, G. Honigfeld, J. Singer, H. Meltzer, Arch. Gen. Psychiatry
1988, 45, 789.
[3] J. M. Alvir, J. A. Lieberman, A. Z. Safferman,
J. L. Schwimmer, J. A. Schaaf, N. Engl. J. Med. 1993, 329, 162.
doi:10.1056/NEJM199307153290303
[4] Z. C. Liu, J. P. Uetrecht, J. Pharmacol. Exp. Ther. 1995, 275, 1476.
[5] A. P. Holstein, C. H. Chen, Am. J. Psychiatry 1965, 122, 462.
[6] B. Capuano, I. T. Crosby, E. J. Lloyd, A. Podloucka, D. A. Taylor, Aust.
J. Chem. 2008, 61, 930. doi:10.1071/CH08307
[7] F. H. L. Awouters, P. J. Lewi, Arzneimittelforschung 2007, 57, 625.
[8] P. Seeman, H. H. M. Van Tol, Trends Pharmacol. Sci. 1994, 15, 264.
doi:10.1016/0165-6147(94)90323-9
[9] B. Costall, D. H. Fortune, R. J. Naylor, V. Nohria, Eur. J. Pharmacol.
1980, 66, 207. doi:10.1016/0014-2999(80)90144-2
[10] B. Costall, R. J. Naylor, V. Nohria, Br. J. Pharmacol. 1978, 63, 381P.
[11] B. Costall, R. J. Naylor, V. Nohria, Eur. J. Pharmacol. 1978, 50, 39.
doi:10.1016/0014-2999(78)90251-0
[12] B. Costall, R. J. Naylor, V. Nohria, Br. J. Pharmacol. 1980, 68, 175P.
[13] J.A. K. Howard,V. J. Hoy, D. O’Hagan, G.T. Smith,Tetrahedron 1996,
52, 12613. doi:10.1016/0040-4020(96)00749-1
Antagonism of Apomorphine-Induced Climbing
in Mice
Adult female mice (20 to 30 g) were used for all the exper-
iments and housed five per cage under controlled conditions
of temperature (20 1◦C) and 12-h light–dark cycle (lights
on 0600–1800 hours), with free access to food and tap water.
The animals were brought into the laboratory and weighed
1 h before the commencement of the experiments to allow for
acclimatization. All compounds assayed were prepared as their
hydrochloride salts and dissolved in water for injections BP
(British Pharmacopoeia) before ip injection. Mice (five per dose)
[14] H. E. Gottlieb,V. Kotlyar,A. Nudelman, J. Org. Chem. 1997, 62, 7512.
doi:10.1021/JO971176V
[15] K. H. Baggaley, E. A. Watts, EP 49060 1982.

124
B. Capuano et al.
[16] P. E. Gagnon, G. Nadeau, R. Cote, Can. J. Chem. 1952, 30, 592.
doi:10.1139/V52-071
[24] T. Irikura, K. Nishino, M. Kitagawa, H. Uchida, N. Ichinoseki,
G. Shishido, JP 19650306 1968.
[17] E. A. Lunney, S. E. Hagen, J. M. Domagala, C. Humblet, J. Kosinski,
B. D. Tait, J. S. Warmus, M. Wilson, D. Ferguson, J. Med. Chem. 1994,
37, 2664. doi:10.1021/JM00043A006
[18] T. Hogberg, G. Bondesson, N. E. Stjernstrom,Acta Pharm. Suec. 1977,
14, 149.
[25] J. C. Pascal, S. Beranger, H. Pinhas, A. Poizot, J. P. Desiles, J. Med.
Chem. 1985, 28, 647. doi:10.1021/JM50001A019
[26] Y. L. Bennani, L. A. Black, W. J. Dwight, R. Faghih, R. G. Gentles,
H. Liu, K. M. Phelan, A. Vasudevan, H. Q. Zhang, WO 2001066534
2001.
[19] S. K. Thompson, J. S. Frazee, L. S. Kallander, C. Ma, J. P. Marino,
M. J. Neeb, A. Bhat, J. J. Mcatee, R. A. Stavenger, WO 2003082205
2003.
[27] F. Ueda, T. Ozaki, K. Nakamura, WO 9604914 1996.
[28] T. Fex, K. G. Olsson, A. L. Abramo, E. G. Christensson, WO 8604584
1986.
[20] B. Jones, J. Chem. Soc. 1935, 1831. doi:10.1039/JR9350001831
[21] F. C. Copp, H. F. Hodson, US 3099599 1963.
[22] P. E. Gagnon, J. L. Boivin, J. Giguere, Can. J. Res. B 1950, 28B, 352.
[23] N. J. Leonard, W. C. Wildman, J. Am. Chem. Soc. 1949, 71, 3089.
doi:10.1021/JA01177A042
[29] B. Capuano, I. T. Crosby, E. J. Lloyd, A. Podloucka, D. A. Taylor, Aust.
J. Chem. 2003, 56, 875. doi:10.1071/CH03030
[30] N. A. Moore, M. S. Axton, Eur. J. Pharmacol. 1990, 178, 195.
doi:10.1016/0014-2999(90)90475-L