Synthesis and pharmacological evaluation of 4-(3,4-dichlorophenyl)-N- methyl-1,2,3,4-tetrahydronaphthalenyl amines as triple reuptake inhibitors

Article abstract of DOI:10.1016/j.bmc.2010.10.034

The present work describes a series of novel chiral amines that potently inhibit the in vitro reuptake of serotonin, norepinephrine and dopamine (triple reuptake inhibitors) and were active in vivo in a mouse model predictive of antidepressant like activi

Full text of DOI:10.1016/j.bmc.2010.10.034

Bioorganic & Medicinal Chemistry 19 (2011) 663–676
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis and pharmacological evaluation of 4-(3,4-dichlorophenyl)-N-methyl-
1,2,3,4-tetrahydronaphthalenyl amines as triple reuptake inhibitors
⇑
Liming Shao , Fengjiang Wang, Scott C. Malcolm, Jianguo Ma, Michael C. Hewitt, Una C. Campbell,
Larry R. Bush, Nancy A. Spicer, Sharon R. Engel, Lakshmi D. Saraswat, Larry W. Hardy, Patrick Koch,
Rudy Schreiber , Kerry L. Spear, Mark A. Varney à
Discovery and Early Clinical Research, Sepracor Inc., 84 Waterford Drive, Marlborough, MA 01752, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
The present work describes a series of novel chiral amines that potently inhibit the in vitro reuptake of
serotonin, norepinephrine and dopamine (triple reuptake inhibitors) and were active in vivo in a mouse
model predictive of antidepressant like activity. The detailed synthesis and in vitro activity and ADME
profile of compounds is described, which represent a previously undisclosed triple reuptake inhibitor
chemotype.
Received 10 August 2010
Revised 10 October 2010
Accepted 13 October 2010
Available online 21 October 2010
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
Triple uptake inhibitor (TRI)
Depression
Antidepressant
Monoamine transporter
1. Introduction
exole) are already used clinically as antidepressants3 and to aug-
ment the effects of traditional antidepressants in treatment of
Commonly used antidepressants increase synaptic availability of
biogenic amines by blocking their transport or reuptake into nerve
terminals, which is the major mechanism for their physiological
inactivation. Examples include norepinephrine and serotonin reup-
take inhibitors (NSRIs) such as venlafaxine and milnacipram, which
inhibit the reuptake of norepinephrine (NE) and serotonin (5-HT),
selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine
(Prozac) and sertraline (Zoloft) and norepinephrine reuptake inhib-
itors (NRIs) such as reboxetine.1 These compounds offer side-effect
advantages over older monoamine oxidase inhibitors (MAOIs),
which block metabolism of biogenic amines to increase synaptic
availability, but offer no clear efficacy advantages. A major drawback
to both reuptake inhibitors and MAOIs is the therapeutic lag2 (slow
onset) associated with their use. The patients must take the drugs for
up to 3 weeks to achieve clinically meaningful symptom relief. Fur-
thermore, the rate of patient response to the treatment is low.
One strategy to reduce therapeutic lag and improve efficacy is
the addition of a dopamine component to a dual reuptake inhibitor
to create a triple reuptake inhibitor (TRI). Dopamine reuptake
inhibitors (e.g., buproprion) and dopamine agonists (e.g., pramip-
refractory patients.4 In addition, deficits in mesocorticolimbic
dopaminergic function have been linked clinically and pre-clini-
cally to anhedonia, which is a core symptom of depression.5
Medicinal chemistry publications and patents from the 1980s
on sertraline analogs disclosed some of the first examples of TRIs.
While sertraline had a (1S,4S)-cis configuration and shows selectiv-
ity for the serotonin transporter, the corresponding (1R,4S)-trans
compound showed potent in vitro inhibition of the serotonin, nor-
epinephrine and dopamine transporters in synaptosomal prepara-
tions of rat brain.6 The TRI theory was further reduced to practice
with DOV-21,9477 and DOV-216,303,8 which both potently inhib-
ited the three monamine transporters (IC50 for 5-HT, NE and DA for
DOV-21,947 = 12, 23, 96 nM and for DOV-216,303 = 14, 20, 78 nM,
respectively), and dose-dependently reduced the duration of
immobility in the forced swim and tail suspension tests in rats,
two models that are highly predictive of antidepressant efficacy
in humans (Fig. 1).
The body of clinical data for triple reuptake inhibitors is
expanding, but has thus far produced mixed results. DOV Pharma-
ceuticals produced the first and only positive Phase II clinical result
for a TRI in 2005. DOV-216,303 was shown in a multicenter, Phase
II study of patients with moderate to severe major depressive dis-
order (n = 67) to be safe and as effective as citalopram.9
In 2009 GSK announced the results of two 10 week, placebo and
active controlled studies (n = 396 and 504 patients) of their bal-
anced TRI (equally potent on SERT, NET and DAT) GSK-372,475
⇑
Corresponding author. Tel.: +1 508 357 7468; fax: +1 508 490 5454.
E-mail address: liming.shao@sepracor.com (L. Shao).
Present address: Evotec, Schnacokenburgallee 114, Hamburg 22525, Germany.
Present address: Cortex Pharmaceuticals, 15231 Barranca Parkway, Irvine, CA
à
92618, USA.
0968-0896/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2010.10.034

664
L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
H
N
H
Cl
Cl
Cl
O
Cl
H
N
H
N
H
Cl
Cl
DOV-21,947
(+)-(3,4-dichlorophenyl)-3-azabicyclo-[3.1.0]-hexane GSK-372,475
DOV-216,303
Figure 1. Structures of DOV-216,303, DOV-21,947 and reported structure of GSK-372,475.
(Fig. 1) in patients with major depressive disorder.10 Neither study
demonstrated a significant benefit for GSK-372,475 versus placebo,
in comparison to a statistically significant improvement in MDD
symptoms for both active controls (venlafaxine and paroxetine).
The hypothesis of the investigators was that the onset of TRI re-
lated side effects thwarted the potential for observing efficacy. Also
in 2009, Sepracor announced that their TRI SEP-225,289 did not
meet its primary efficacy endpoint, reduction in symptoms of
depression following 8 weeks of treatment, in a Phase II, 514 pa-
tients study. Positive control venlafaxine did separate from placebo
and achieve a reduction in the symptoms of depression as judged
by the 17 item HAM-D scale.11 In this study, the measured serum
concentrations of SEP-225,289 were far below expected levels of
exposure for both doses studied and were well below exposure
profiles observed in several Phase I studies. In addition, the side ef-
fect profile seen in the treatment group was similar to the placebo
group and inconsistent with prior clinical observations. While the
clinical data from GSK and Sepracor were disappointing with re-
spect to advancement of a TRI to the marketplace, the results high-
lighted the difficulties inherent in fine-tuning three different
neurotransmitters to create a clinically effective triple reuptake
inhibitor. Significant challenges remain in the discovery of novel
compounds that modulate 5-HT, NE and DA levels to varying
degrees. The present work discloses our efforts to develop novel
TRIs with variable levels of reuptake inhibition at the three
neurotransmitters.
as monoamine reuptake inhibitors (Fig. 2). Our goal was to probe
the SAR of these novel chiral amines as potential TRIs and create
novel chemotypes that possessed varying degrees of reuptake inhi-
bition at SERT, NET and DAT. The synthesis, detailed SAR of the
scaffolds and their inhibition against SERT, NET and DAT are de-
tailed below.
2. Results and discussion
2.1. Chemistry
Synthesis of the initial set of chiral amines (Scheme 1) began
from commercially available
a-tetralone 5, which was reduced
with sodium borohydride and dehydrated with H2SO4 to give al-
kene 6. Dihydroxylation and treatment with p-TsOH gave the key
b-tetralone intermediate 8. Reductive amination provided amines
9 and 10; Eschweiler–Clarke12 alkylation of secondary amine 10
provided tertiary amine 11.
The synthesis of the second set of amines also commenced from
tetralone 5, which was acylated with diethylcarbonate to give mal-
onate derivative 12, then reduced with triethylsilane/TFA to give
ester 13 (Scheme 2). Reduction with LAH was followed by bromin-
ation (to 15) and displacement with sodium azide to give 16. Pri-
mary amine 17 was obtained as a mixtures of diastereomers
after hydrogenation of the azide with Pd/C. The mono (18) and
di-methyl amine (19) derivatives were synthesized via SN2 dis-
placement of the alkyl bromide with methyl and dimethyl amine
solutions, respectively.
While trans-sertraline (1) and congener cis-sertraline (Zoloft)
are known to be monoamine reuptake inhibitors (vida infra), novel
chiral amines 2, 3 or 4 had never, to our knowledge, been reported
HN
NHR
( )n
NHR
Cl
Cl
Cl
Cl
Cl
Cl
2
3
1
(1R,4S)-trans-Sertraline
Triple reuptake inhibitor
NHR
Cl
Cl
4
Figure 2. Novel chiral amines 2, 3 and 4.

L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
665
made using chiral HPLC analyses. For example, authentic samples
could be spiked into enantiomeric and/or diastereomeric mixtures
to allow for a correlation of retention times and structures. Using
the synthetic methods outlined in Scheme 3 and described above,
the absolute configuration of compounds 9a–d, 10a–d, 11a–d,
17a–d and 18a–d (Schemes 3 and 4) could be determined.
O
1. NaBH4
OsO4
NMO
2. H2SO4/SiO2
Ar
Ar
6
5
We also chose to evaluate the one-carbon extended version of
compounds 17–19, with an ethylene linker between the tetralone
and amine moieties (Scheme 5). Starting from the same b-tetralone
8, we carried out a Wittig reaction with dimethyl cyanomethyl-
phosphonate, followed by hydrogenation and reduction to give
racemic 21. Installation of a BOC group allowed chiral separation
to be carried out (Chiral Technologies OD column and a solvent sys-
tem of 90% hexanes/10% IPA/0.1% diethylamine); removal of the BOC
group gave single enantiomer (cis) compounds 21a and 21b.
Ketone 22 was the starting point for the synthesis of the final
set of chiral amines 24a–d (Scheme 6). Pd-catalyzed arylation with
1-bromo-3,4-dichlorobenzene and reductive amination with
methyl amine hydrochloride and sodium cyanoborohydride deliv-
ered the crude target compounds, which could be resolved by chi-
ral HPLC with the OD column and two different solvent systems
(see Supplementary data for details). The relative (cis/trans) config-
urations were determined based on 1H NMR coupling patterns and
by comparison to reported values for similar compounds.13 The
absolute configurations of 24a–d were assigned arbitrarily.
OH
O
OH
1) TsOH; -H2O
2) Chrom.
Ar
8
Ar
7
R3
N
R3R4NH2Cl
NaCNBH3
R4
Ar
R3 = R4 = H
Ar =
9
10 R3 = H, R4= Me
Cl
Cl
CH3
N
CH3
HCOOH
HCHO
10
Ar
11
2.1.1. In vitro pharmacology
Table 1 details the pharmacological characterization of our no-
vel triple reuptake inhibitors – in vitro data on inhibition of human
recombinant serotonin,14 norepinephrine15 and dopamine16
transporters.
For the first set of chiral amines (9a–d, 10a–d and 11a–d), po-
tency against SERT increased as the substitution on the amine in-
creased, with trans mono-methyl amines 10a (IC50 for 5-HT,
6 nM) and cis dimethyl amine 11c (3 nM) as standouts. For NET,
mono-methyl amines such as 10a (IC50 for NE, 27 nM), 10c (IC50
Scheme 1. Synthesis of chiral amines 9–11.
Assignments of relative stereochemistries were made using
NMR techniques (determination of cis- and trans-configurations,
optionally using literature reports for similar compounds). Abso-
lute stereochemistries of selected compounds were determined
by synthesis of key intermediates from commercially-available
(S)-a-tetralone as outlined in Scheme 3, below. Correlations were
O
O
O
O
Et
Et
O
O
EtO2CO2Et
LAH, THF
Et3SiH, TFA
NaH, THF, reflux
Ar
Ar
Ar
12
13
5
OH
Br
N3
NaN3
CBr4, Ph3P
CH2Cl2
DMF, 50 ºC
Ar
Ar
Ar
14
15
16
R3
R4
H2, Pd/C
NH2
N
H
R3
N
Ar =
R4
Cl
Ar
Ar
Cl
18 R3 = H, R4 = Me
19 R3 = R4 = Me
17
Scheme 2. Synthesis of amines 17–19.

666
L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
Determined by NMR and chiral HPLC
comparison to (S)-tetralone cmpds
NMR and Synthesis from (S)-tetralone
NH2
NH2
NH2
NH2
Scheme 1
O
(S)
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
9a
9c
9b
9d
Cl
Cl
NH2
NH2
NH2
NH2
(S)-α-tetralone
Scheme 2
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
17a
17c
17b
17d
Scheme 3. Synthesis of 9a, 9c, 17a and 17c using (S)-a-tetralone starting material, and determination of configuration of 9b, 9d, 17b and 17d by analogy and comparison via
chiral HPLC.
R1
N
R1
N
R1
N
R1
N
R2
R2
R2
R2
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
9a, R1 = R2 = H
9b, R1 = R2 = H
10b, R1 = H, R2 = CH3
11b, R1 = R2 = CH3
9c, R1 = R2 = H
10c, R1 = H, R2 = CH3
11c, R1 = R2 = CH3
9d, R1 = R2 = H
10d, R1 = H, R2 = CH3
11d, R1 = R2 = CH3
10a, R
1
= H, R2 = CH3
11a, R1 = R2 = CH3
R1
R1
N
R1
N
R1
N
N
R2
R2
R2
R2
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
17c, R1 = R2 = H
18a, R1 = H, R2 = CH3
17d, R1 = R2 = H
18b, R1 = H, R2 = CH3
17a, R1 = R2 = H
18c, R1 = H, R2 = CH3
17b, R1 = R2 = H
18d, R1 = H, R2 = CH3
19b, racemic trans, R1 = R2 = CH3
19a, racemic cis, R1 = R2 = CH3
Scheme 4. Absolute configuration of amines 9, 10, 11, 17 and 18a–d and relative configuration of racemic compounds 19a–b.
for NE, 45 nM) and 10d (IC50 for NE, 73 nM) showed good potency,
There was a pronounced effect of chirality at the dichlorophenyl
aromatic position with respect to SERT reuptake inhibition in the
first series of compounds. Compounds derived from (S)-tetralone
showed potent inhibition at SERT compared with (R)-tetralone de-
rived analogs, regardless of substitution of the amine portion of the
compound and cis/trans configuration of the amine and dichloro-
phenyl moieties. The clear preference for the (S)-derived com-
pounds at SERT was quite striking and must be due to the
serotonin transporter having a binding pocket that was nicely
occupied by the (S)-dichlorophenyl tetralone pharmacophore. This
result was also consistent with what the Pfizer group found in their
investigations of sertraline. Only the cis-(1S,4S) and trans-(1R,4S)
while the primary amines provided some of the least potent com-
pounds in the initial set with respect to NET (i.e., compounds 9b
and 9c). Mono-methyl amines such as 10b (IC50 for DA, 62 nM)
and 10d (IC50 for DA, 72 nM) provided good potency against
DAT; the primary and tertiary amines were generally worse than
the secondary amines against DAT for the first set of compounds.
In terms of triple reuptake inhibitor development potential, com-
pound 10a and 10c showed the most potential, with excellent po-
tency against SERT and NET and slightly decreased potency against
DAT. Clinically this might be a benefit in that patients would
achieve symptom relief without a risk of dependence.

L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
667
O
NH2
CN
MeO2POCH2CN
1) H2, Pd/C
2) BH3
Ar
20
Ar
Ar
8
21
NH2
NH2
1. BOC2O
2. Chiral HPLC
3. TFA
Ar =
Cl
Cl
Cl
Cl
Cl
Cl
21a
21b
Scheme 5. Synthesis of amino-ethyl derivatives 21a and 21b.
LiHMDS, tBu3P
Pd(dba)2, toluene
μW
CH3NH2 HCl
NaHCNBH3, MeOH/THF
N
H
O
O
Br
22
23
24
Cl
Cl
Cl
Cl
Cl
Cl
OD column
98/2/0.1 hex/IPA/DEA
and 95/2/3/0.1 hex/MeOH/EtOH/DEA
N
H
N
H
N
N
H
H
Cl
Cl
Cl
Cl
Cl
24a
Cl
Cl
Cl
24b
24c
24d
Scheme 6. Synthesis of d-tetralones 24a–d.
compounds showed reuptake inhibition activity.6a The (R)-tetra-
lone derived compounds showed moderately increased inhibition
of the dopamine transporter compared with their (S)-tetralone de-
rived congeners, although the effect was less pronounced than the
SERT effect described above. The influence of chirality on NET was
less clear in the first series of compounds, as was any preference
for a cis or trans relationship between the dichlorophenyl and
amine moieties (compare trans-10a to cis-10c).
For the amino-methyl derivatives 17–19, the primary and sec-
ondary amines exhibited excellent potency, with a number of ana-
logs active against all three transporters. The most potent SERT
inhibitors were found among the primary amines, with 17a (IC50
for 5-HT, 2 nM) and 17c (IC50 for 5-HT, 1 nM) in the low single dig-
its. The secondary amine 18a was also among the best SERT inhib-
itors (IC50 for 5-HT, 9 nM). NET inhibition was more varied, with
both primary amine 17a (IC50 for NE, 28 nM) and secondary amine
18a (IC50 for NE, 72 nM) providing compounds with potencies
<100 nM. For the dopamine transporter, the most potent inhibitors
were found amongst the primary amines of the second set, with
17a and 17c as standouts. As for TRI potential, primary amine
17a and 17c and secondary amine 18a looked the best, with sero-
tonin and norepinephrine reuptake more potent than dopamine
reuptake inhibition in vitro. Methylene extended compounds 21a
and 21b were both potent inhibitors against the three transporters,
although 21a was superior across all three transporters.
For the amino-methyl series (compounds 17–19), the chirality
at the dichlorophenyl attachment showed a significant impact on
SERT activity with analogs derived from (S)-tetralone being more
potent against SERT, and similar results were also obtained for po-
tency against NET for primary and secondary amines (i.e., com-
pounds 17a–d and 18a–b). For potency against all three
transporters, primary amine 17a was the best compound, while
secondary amines such as 18a showed ratios that might be more
favorable clinically to avoid risks of dependence while providing
maximum amounts of postsynaptic serotonin and norepinephrine.
The d-tetralone compounds 24a–d did not show potent inhibi-
tion against all three transporters in general, with only compound
24a showing potential as a selective sertotonin and dopamine

668
L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
Table 1
inhibition, while the (R)-configured congeners 10b and 10d
showed micromolar inhibition. For the other series of compounds
it was more difficult to correlate the CYP2D6 inhibition with any
one structural feature. The profiled compounds showed minimal
inhibition against CYP1A, 2C9 and 3A4, although 18b and 21b
a
Compound
IC50 (nM)
5-HT
NE
DA
310
Sertraline (zoloftÒ
)
3
50b
46
1830
84
108
6
125
8
107
7
108
3
20
2
19
1
61
9
54
23
16
825
22b
124
731
855
174
27
21
exhibited some CYP2C19 inhibitory activity (IC50 ꢀ2
of the compounds also had significant hERG inhibition; 10b, 10d,
18a and 18c all had IC50’s around 2 M and could pose a concern
lM). Several
1 (trans-sertraline)6a
60b
350
408
894
175
114
62
9a
9b
9c
9d
10a
10b
10c
10d
11a
11b
11c
11d
17a
17b
17c
17d
l
from a safety perspective. When the in vitro ADME data were
viewed as a whole, 10d and 21b stood out as having the best pro-
files. Although both showed some CYP inhibition (CYP2C19 inhibi-
tion for 21b and CYP2D6 for 10d) and both also showed moderate
hERG inhibition, the liabilities were not viewed as fatal flaws. The
potent reuptake inhibition for the two compounds could provide a
reasonable therapeutic index and might make it possible to avoid
concentrations in vivo that could make the CYP and hERG inhibi-
tion a safety concern. With this in mind, compound 10d was cho-
sen as the better of the two based on potency against the three
transporters and profiling in the mouse tail suspension test18
was initiated. The assay is not a model of depression, but is sensi-
tive to the effects of several classes of antidepressants, including
tricyclics, SSRIs and SNRIs.
117
45
281
72
73
167
174
164
98
454
176
273
319
11
111
45
92
125
103
111
484
332
339
32
28
257
92
371
72
18a
18b
18c
18d
126
210
372
565
309
26
158
766
112
1642
7262
19a mixture of cis-enantiomers
19b mixture of trans-enantiomers
311
970
1
79
42
1956
2495
2827
2.1.3. Pharmacology
21a
21b
24a
24b
24c
24d
The HCl salt of 10d was prepared and dosed 3, 10 and 30 mg/kg
po in male mice in the tail suspension test (TST). A 120 min pre-
treatment time was used based on exposure work prior to the as-
say which showed maximal brain levels 120 min after po dosing.
10d showed a nice dose dependent reduction in immobility, which
was statistically significant compared to vehicle at 10 and
30 mg/kg doses (Fig. 3a). The positive control, desipramine, also
50
91
559
212
1616
a
SERT, NET and DAT reuptake inhibition assays were run with at least n = 2 and
five concentrations to generate inhibition curves, from which IC50’s were deter-
mined. Assay performance was monitored by the use of SERT reference compound
fluoxetine (IC50 = 5.2 0.6 nM), NET reference compound nisoxetine (IC50 = 8.3
1.0 nM) and DAT reference compound nomifensine (IC50 = 30.2 2.2 nM).
IC50 values for trans-sertraline were for inhibition of monoamine uptake into rat
brain synaptosomes. Sertotonin and dopamine taken from corpus striatum, nor-
epinephrine from hypothalamus.
showed
a statistically significant reduction in immobility at
100 mg/kg po. Brain and plasma samples taken from the testing
animals showed that the brain to plasma ratio was close to 40 at
the 30 mg/kg dose, with almost 44 lM of 10d in the brain (Table
b
3). Even given the high degree of protein binding we measured
for compound 10d (99% protein binding using mouse plasma pro-
tein), the brain free fraction for compound 10d was estimated to be
ꢀ440 nM, which exceeded the IC50 at all three transporters. Plasma
protein binding can be a surrogate for brain binding if the com-
pound freely diffuses into the brain and no efflux is present (no ef-
flux as judged by A?B/B?A permeability in the CaCO-2 cell line
was seen in the compound series, data not shown).19 The effect
of compound 10d (Fig. 3b), in the TST was also not due to a general
locomotor activation effect; the compounds did not significantly
increase spontaneous locomotor activity in vivo in the first 5 min
at the 10 or 30 mg/kg dose. The 5 min time point was significant
because that is the amount of time the compounds were evaluated
in the TST.
reuptake inhibitor (SDRI). Moving the amino group to the C-3 posi-
tion on the tetralone scaffold appeared to be negative with respect
to broad activities against the three transporters.
2.1.2. In vitro ADME: microsomal stability, CYP and hERG
inhibition
The secondary amines 10a–10d, 18a–18c, racemic primary
amines 21a and 21b and d-tetralones 24a–d were chosen for pro-
filing in CYP and hERG inhibition and microsomal stability assays
based on their potency against the three transporters. All com-
pounds profiled showed exceptional stability in human and mouse
liver microsomes, with t1/2 exceeding 300 min in almost every
case. In the CYP inhibition assay, the compounds began to differen-
3. Conclusions
tiate; significant (IC50 <1 lM) CYP2D6 inhibition was seen for com-
The goal of the present work was to explore the potential of
novel triple reuptake inhibitors as treatments for depression.
We succeeded in that goal by showing a wide range of chiral
amines with potent reuptake inhibition at SERT, NET and DAT.
CYP and hERG inhibition emerged as a problem area for the de-
signed compounds, with most of the compounds showing potent
pounds 10a, 10c, 18a–c, and 21a and potent inhibition for 24a–d
(Table 2). We were not that surprised by the CYP2D6 inhibition
for our test compounds—structurally related cis sertraline shows
mild inhibition of CYP2D6 and can result in a 10–50% elevation
of plasma levels of a co-administered CYP2D6 substrate such as
dextromethmorphan.17 There was also a clear correlation between
CYP2D6 inhibition and the configuration of the dichlorophenyl aro-
matic moiety for compounds 10a–d, which were most closely
structurally related to sertraline. Compounds 10a and 10c, with
an (S)-configuration of the dichlorophenyl aromatic (like sertraline
and trans-sertraline), showed significant (nanomolar) 2D6
inhibition of CYP2D6 and several showing IC50’s <2 lM for the
hERG potassium channel. Compound 10d was shown to be a
promising candidate for further optimization due to its potent
inhibition of SERT, NET and DAT, good stability in vitro and rela-
tively clean profile against the CYPs and hERG. In vivo testing of

L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
669
Table 2
In vitro microsomal stability, CYP and hERG inhibition
Structure
Compound
Microsomal stability t1/2 (min)
Human Mouse
CYP450 inhibition IC50
(
l
M)
hERG IC50 (lM)
1A
2C9
2C19
2D6
3A4
0.8
NH
Sertraline
>120
nta
>10
>10
0.31
1.4
nt
Cl
Cl
Cl
H
N
CH3
10a
>300
>300
>25
>25
>25
0.067
>25
nt
Cl
H
N
CH3
CH3
CH3
10b
>300
120
>25
>25
5.26
1.16
>25
2.32
Cl
Cl
Cl
H
N
10c
>300
>300
>25
>25
>25
0.020
>25
5.27
Cl
H
N
10d
>300
>300
>25
>25
10.15
2.78
17.1
1.60
Cl
Cl
Cl
Cl
CH3
N
H
18a
>300
>300
>25
>25
7.69
0.041
20.1
1.61
CH3
N
H
18b
>300
93
>25
>25
2.17
0.917
>25
nt
Cl
Cl
(continued on next page)

670
L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
Table 2 (continued)
Structure
Compound
Microsomal stability t1/2 (min)
CYP450 inhibition IC50
(
lM)
hERG IC50 (lM)
Human
Mouse
1A
2C9
2C19
2D6
3A4
>25
CH3
NH2
NH2
N
H
18c
>300
>300
>300
>300
>25
>25
6.02
0.154
2.0
Cl
Cl
Cl
21a
>300
>25
>25
3.76
0.265
>25
13.1
Cl
Cl
21b
>300
20.7
>25
1.64
13.8
>25
1.51
Cl
Cl
Cl
Cl
Cl
N
H
24a
24b
24c
24d
106
101
55
20
6
nt
nt
nt
nt
>10
nt
nt
nt
nt
0.008
0.033
0.057
0.495
nt
nt
nt
nt
nt
nt
nt
nt
Cl
N
H
55
7.6
Cl
N
H
95
>10
Cl
N
H
55
>10
Cl
Human microsomal stability data for sertraline taken from Ref. 17. CYP inhibition for sertraline was determined at CEREP, using assay codes 900-1 (1A2), -4 (2C9), -6 (2D6), -2
(2C19) and -3 (3A4). Microsomal stability, CYP and hERG inhibition for all compounds other than sertraline determined at Cyprotex using their standard protocols, with
midazolam as the reference substrate for CYP3A4.
a
nt, not tested.
compound 10d in the mouse tail suspension test confirmed its
potential as an antidepressant; the compound was active at 10
and 30 mg/kg po and its activity was not due to a general loco-
motor activating effect. Given that compound 10d was not the
most potent triple reuptake inhibitor we disclosed in this paper,
and yet was still orally active in vivo in a rodent model of depres-
sion, we feel the triple reuptake inhibition landscape is tremen-
dously fertile with opportunities for development of
antidepressants. Future publications will disclose our efforts
along those lines.

L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
671
Figure 3. (a) Compound 10d in the mouse TST at 3, 10 and 30 mg/kg po. (b) Compound 10d in mouse locomotor activity assay at 5 min time point, at 3, 10, and 30 mg/kg po.
2.2–1.9 (m, total 3H), 1.8 (m, 1H). 13C NMR (CDC13) d 146.9,
146.8, 139.6, 138.9, 138.3, 137.7, 132.3, 132.2, 130.6, 130.5,
Table 3
Whole brain and plasma levels of compound 10d from TST animals
130.3, 130.2, 129.8, 129.7, 129.0, 128.2, 128.1, 128.1, 128.0,
127.9, 127.1, 127.0, 68.1, 67.7, 45.0, 44.4, 30.0, 29.9, 28.9, 28.1.
Compound Dose (mg/kg), po Plasma levels (ng/mL) Brain levels (ng/g)
10d
3
10
30
96
164
344
2830
6021
13,571
4.1.1.2. Synthesis of 1-(3,4-dichlorophenyl)-1,2-dihydronaph-
thalene (6). To a solution of the crude alcohol 4-(3,4-dichloro-
phenyl)-1,2,3,4-tetrahydro-naphthalen-1-ol (53 g) in toluene
(500 mL) was added silica gel coated with sulfuric acid (3%, 14 g).
The mixture was heated to 100 °C and monitored by TLC (prod Rf
(25% EA/hex) = 0.58). After 3 h, the mixture was filtered. The organ-
ic phase was washed with water and sodium bicarbonate solution,
dried (Na2SO4), and evaporated to give the alkene 6 (42 g, 84%) as a
pale-brown solid. GC–MS Rt = 13.55 min, m/z = 274 (M+). 1H NMR
(CDCl3) d 7.4–6.7 (m, 7H), 6.54 (d, J = 9.6 Hz, 1H), 6.0 (m, 1H),
4.08 (t, J = 8.0 Hz, 1H), 2.7 (m, 1H), 2.5 (m, 1H). 13C NMR (CDCl3)
d 143.6, 136.3, 133.8, 132.2, 130.2, 130.2, 128.1, 127.7, 127.2,
126.4, 129.7, 127.4, 42.8, 31.6.
4. Experimental section
4.1. Chemistry
4.1.1. General statement
Reagents were commercial grade and were used as received un-
less otherwise noted. Reactions were run with anhydrous solvents
under an atmosphere of nitrogen unless otherwise noted. Flash
column chromatography was done using an IscoÒ purification sys-
tem on silica gel columns. The structures of all new compounds
were consistent with their 1H, 13C NMR and mass spectra and were
judged to be >95% pure. Purified chiral compounds were all >95%
enantiomeric excess (ee). Chiral chromatography was done using
the designated Chiral Technologies Chiracel 20 micron analytical
(0.46 cm ID ꢁ 25 cm L) column, a flow rate of 1 mL/min with the
designated solvent, with detection by UV at 220 and 254 nM. LC–
MS was performed on an Agilent 1100 Series system connected
to a Micromass Platform LC. GC–MS was performed on a Hewlett
Packard 6890 Series GC System with an HP1 column (30 m,
4.1.1.3. Synthesis of 4-(3,4-dichlorophenyl)-3,4-dihydro-1H-
naphthalen-2-one (8). To a stirring solution of the alkene 6 (3 g,
10.8 mmol) in acetone (40 mL) was added NMO (2 g, 1.6 equiv)
and water (10 mL). After the NMO dissolved, osmium tetroxide
(1.3 mL, 0.1 M in toluene, 5 mol %) was added and the solution was
stirred at ambient temperature for 40 min. Sodium bisulfate
(10 mL, 10% solution in water) was added and the mixture was stir-
red for an additional 30 min. After this time, the solvent was re-
moved in vacuo and the resultant oily solid was partitioned
between MTBE and, sequentially, water and brine. The organic sol-
vent was evaporated to yield the crude diol (3.6 g) as a brown glass.
TLC Rf (50% EA/hex) = 0.14. The crude diol (7) was sufficiently pure
for the next step, and could be confirmed by the three diagnostic
peaks that were discernable in the 1H NMR (4.8, 4.4, 4.2 ppm).
The diol 7 was dissolved in toluene (200 mL). Tosic acid
(600 mg, 30 mol %) was added and the solution was heated to re-
flux in a Dean–Stark trap until the diol was consumed. After 3 h,
the reaction mixture was cooled and most of the toluene was re-
moved. The remaining liquid was partitioned between MTBE and,
sequentially, 10% aqueous KOH, water, and brine. The organic layer
was evaporated and the crude green oil was separated on silica gel
to give the b-tetralone 8 (1.46 g, 46%) as a pale-yellow oil. GC–MS
0.15
l film thickness) coupled to a Hewlett Packard 5973 Series
Mass Selective Detector. Accurate mass measurements were car-
ried out on a Waters Q-TOF micro system.
4.1.1.1. Synthesis of 4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-
naphthalen-1-ol. To a stirring mixture of
chloro-phenyl)-3,4-dihydro-2H-naphthalen-1-one
a
-tetralone 4-(3,4-di-
(53 g, l82
5
mmol) in methanol (400 mL) was added sodium borohydride
(12 g) in portions. The mixture was stirred at ambient temperature
for 3 h. Water was added and the volatile components were re-
moved in vacuo. The aqueous remainder was extracted with ethyl
acetate. The organic phase was separated, washed with water,
dried (Na2SO4), and evaporated to dryness to yield the crude mix-
ture of diastereomeric alcohol 4-(3,4-dichlorophenyl)-1,2,3,4-tet-
rahydro-naphthalen-1-ol (53 g). 1H NMR (CDC13) d 7.58–6.8 (m,
7H), 4.84 (m, 1H), 4.15 (t) and 3.92 (m, total 1H), 2.38 (m) and
Rt = 13.54 min, m/z = 290 (M+). 1H NMR (CDCl3)
J = 8.0 Hz, 1H), 7.3–7.2 (m, 4H), 7.0–6.9 (m, 2H), 4.42 (t,
d 7.39 (d,

672
L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
J = 6.4 Hz, 1H), 3.62 (q, J = 20 Hz, 2H), 2.9 (m, 2H). 13C NMR (CDCl3)
d 208.2, 141.7, 137.7, 133.0, 132.8, 131.0, 130.6, 129.8, 128.7,
127.8, 127.5, 127.1, 45.4, 44.5, 43.8.
dium bicarbonate and extracted with MTBE. The combined organic
layer was washed with brine and evaporated to give a brown-
green oil. The oil was dissolved in MTBE and extracted into 10%
aqueous hydrochloric acid. The aqueous layer was basicified with
KOH and extracted with MTBE. The volatile components were re-
moved in vacuo and the crude green oil was separated on silica
gel to give the methylamine (0.20 g, 54%) as a pale-green oil.
As isolated, the amine was a mixture of four stereoisomers
which were separable on chiral columns. First, the mixture was
separated on a Chiracel OD column (98:2:0.1 Hex/IPA/DEA) to give
three fractions. Symchiral trans (compound 10a) at 12.4 min, race-
mic cis at 15.8 and 17.6 min, and symchiral trans (compound 10b)
at 29.7 min. The racemic cis was then resubmitted to a Chiracel AD
column (98:2:0.1 Hex/IPA/DEA) to give the symchiral cis (Com-
pound 10c) at 20.2 min and symchiral cis (SME compound 10d)
at 27.7 min. Retention times are summarized in Table 5, below.
Absolute stereochemistries of compounds 10a–d were deter-
mined using a combination of NMR techniques (determination of
cis- and trans-configurations) and chiral HPLC analyses using
4.1.1.4. Synthesis of [4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-
naphthalen-2-yl]-amine (9a–d). Ammonium chloride (643 mg,
l0 equiv) was dissolved in methanol (24 mL) by heating to 50 °C.
After it cooled, a solution of ketone 8 (350 mg, 1.202 mmol) in
THF (18 mL) was added followed by sodium cyanoborohydride
(6.0 mL, 5 equiv). The mixture was heated in a 50 °C oil bath over-
night. The reaction was then cooled, quenched with aqueous so-
dium bicarbonate, and extracted with MTBE. The combined
organic layer was washed with brine and evaporated to give a
brown-green oil. The oil was separated on silica gel to give the pri-
mary amine 9 (145 mg, 41%) as a pale-green oil.
As isolated, the amine was a mixture of four stereoisomers
which were separable using chiral columns. First, the mixture
was separated on a Chiracel OD column (90:10:0.1 Hex/IPA/DEA)
to give three fractions. Symchiral trans (compound 9a at
11.9 min, racemic cis at 14.7 min, and symchiral trans (compound
9b) at 22.3 min. The racemic cis was then resubmitted to the Chira-
cel AD column 95:2:3:0.1 Hex/MeOH/EtOH/DEA) to give the sym-
chiral cis (Compound 9c) at 11.1 min and symchiral cis (compound
9d) at 13.9 min. Retention times are summarized in Table 4, below.
Absolute stereochemistries for compounds 9a–d were deter-
mined using a combination of NMR techniques (determination of
cis- and trans-configurations) and chiral HPLC analyses using
authentic samples, which were prepared from commercial (S)-a-
tetralone as described above. The resulting structures indicating
absolute stereochemistries are shown below:
H
N
H
N
H
N
H
N
CH3
CH3
CH3
CH3
Cl
Cl
Cl
Cl
authentic samples, which were prepared from commercial (S)-a-
tetralone as described above. The resulting structures indicating
absolute stereochemistries are shown below:
Cl
Cl
Cl
Cl
10a
10b
10c
10d
4.1.1.5.1. trans-Isomers 10a and 10b. HRMS [M+H]+: calcd for
(10a) C17H18Cl2N 306.0811, found 306.0832; LC–MS Rt = 8.3 min,
m/z = 306 (M+1). GC–MS Rt = 13.64 min, m/z = 305 (M+). 1H NMR
(CDC13) d 7.4–6.8 (m, 7H), 4.26 (t, J = 5.8 Hz, 1H), 3.15 (dd, J = 4.6,
16.2 Hz, 1H), 2.9 (m, 1H), 2.66 (dd, J = 7.8, 16.2 Hz, 1H), 2.43 (s,
3H), 2.0 (m, 2H. 13C NMR (CDC13) d 147.5, 136.8, 135.6, 132.2,
130.6, 130.1, 129.9, 129.8, 129.5, 128.1, 126.7, 126.2, 51.1, 42.5,
37.8, 36.0, 33.7.
NH2
NH2
NH2
NH2
Cl
Cl
Cl
Cl
Cl
9a
Cl
9b
Cl
9c
Cl
9d
4.1.1.5.2. cis-Isomers 10c and 10d. HRMS [M+H]+: calcd for
(10c) C17H18Cl2N 306.0811, found 306.0822; LC–MS Rt = 8.5 min,
m/z = 306 (M+1). GC–MS Rt = 13.82 min, m/z = 305 (M+). 1H NMR
(CDC13) d 7.4–6.7 (m, 7H), 4.08 (dd, J = 5.4, 12.2 Hz,1H), 3.12
(ddd, J = 2.2, 4.7, 15.7 Hz, 1H), 2.93 (ddt, J = 2.9, 4.8, 11.2 Hz, 1H),
2.70 (dd, J = 11.1, 15.7 Hz, 1H), 2.52 (s, 3H), 2.3 (m, 1H), 1.6 (m,
1H). 13C NMR (CDC13) d 146.8, 138.2, 135.8, 132.4, 130.6, 130.5,
130.2, 129.2, 129.0, 128.1, 126.4, 126.1, 55.5, 45.8, 40.5, 37.4, 33.6.
4.1.1.4.1. trans-Isomers 9a and 9b. GC–MS Rt = 13.52 min, m/
z = 291 (M+). 1H NMR (CDC13)
7.4–6.8 (m, 7H), 4.32 (t,
J = 5.4 Hz, 1H), 3.3 (m, 1H), 3.17 (dd, J = 4.9, 16.3 Hz, 1H), 2.7 (m,
1H), 2.1 (m, 2H). 13C NMR (CDC13) d 160.3, 147.2, 136.0, 135.2,
132.3, 130.5, 130.1, 130.0, 129.5, 128.0, 126.9, 126.5, 43.2, 42.9,
40.2, 38.2.
4.1.1.4.2. cis-Isomers 9c and 9d. GC–MS Rt = 13.61 min, m/
z = 291 (M+). 1H NMR (CDC13) d 7.4–6.7 (m, 7H), 4.11 (dd, J = 5.5,
12.1 Hz, 1H), 3.26 (ddt, J = 3.1, 4.9, 11.3 Hz, 1H), 3.07 (ddd, J = 2.2,
4.8, 15.9 Hz, 1H), 2.7 (m, 1H), 2.2 (m, 1H), 1.6 (m, 1H). 13C NMR
(CDC13) d 146.7, 137.8, 135.9, 132.4, 130.6, 130.5, 129.1, 129.1,
128.1, 126.5, 126.2, 130.2, 47.6, 46.0, 44.4, 40.2.
d
4.1.1.6. Synthesis of [4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-
naphthalen-2-yl]-dimethylamine
(11a–d). The
respective
methylamine 10 (e.g., 28.4 mg, 0.0927 mmo1) was dissolved in
96% formic acid (0.5 mL) and 37% aqueous formaldehyde (0.5 mL)
and heated at 100 °C for 2 h. After cooling, the solution was basici-
fied (aq KOH) and extracted with MTBE. The organic phase was
dried with sodium sulfate, filtered, and evaporated to give the
dimethylamine (e.g., 27.1 mg, 93%) as a clear oil.
4.1.1.5. Synthesis of 4-(3,4-dichlorophenyl)-N-methyl-1,2,3,4-
tetrahydronaphthalen-2-amine (10a–d). To a solution of ketone
8 (350 mg, 1.202 mmol) in THF (18 mL) and methanol (24 mL) was
added methylamine hydrochloride (980 mg, 10 equiv). After the
solid dissolved, sodium cyanoborohydride (6.0 mL, 1 M in THF,
5 equiv) was added in one portion. The mixture was heated in a
50 °C oil bath overnight before being quenched with aqueous so-
Absolute stereochemistries for compounds 11a–d were deter-
mined and are shown below:
Table 4
Table 5
Retention times for each diastereomer [min]
Retention times for each diastereomer [min]
9a
9c
9d
9b
10a
10c
10d
10b
trans cis
cis
trans
trans
cis
cis
trans
HPLC Rt (Chiracel OD, 90:10:0.1 Hex/IPA/DEA)
HPLC Rt (Chiracel AD, 95:2:3:0.1 Hex/MeOH/
EtOH/DEA)
11.9
14.7 14.7 22.3
11.1 13.9
HPLC Rt (Chiracel OD, 98:2:0.1 Hex/IPA/DEA)
HPLC Rt (Chiracel AD, 98:2:0.1 Hex/IPA/DEA)
12.4
15.8
20.2
17.6
27.7
29.7

L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
673
1.80 g, 80%). 1H NMR (CDC13) d 1.31–1.54 (m, 1H), 1.92–1.98 (m,
1H), 2.10–2.26 (m, 1H), 2.54–2.71 (m, 1H), 2.92–3.03 (m, 1H),
3.53–3.75 (m, 2H), 4.07 (dd, J = 12 Hz, 5.2 Hz) and 4.25 (t,
J = 3.6 Hz, total 1H), 6.72–7.38 (m, 7H). 13C NMR (CDC13) d 32.0,
32.5, 33.4, 34.6, 37.5, 37.6, 43.3, 46.3, 67.5, 67.9, 126.3, 126.4,
126.6, 127.0, 128.4, 128.5, 129.5, 129.7, 130.2, 130.5, 130.7,
130.9, 132.4, 132.7, 136.7, 136.9, 138.8, 147.5, 147.9.
CH3
N
CH3
N
CH3
N
CH3
N
CH3
CH3
CH3
CH3
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
11a
11b
11c
11d
4.1.1.6.1. trans-Isomers 11a and 11b. LC–MS Rt = 9.0 min,
m/z = 320 (M+l). 1H NMR (CDC13) d 7.4–6.8 (m, 7H), 4.32 (t,
J = 5.4 Hz, 1H), 3.02 (dd, J = 4.8, 16.3 Hz, 1H), 2.84 (dd, J = 9.3,
16.3 Hz, 1H), 2.6 (m, 1H), 2.27 (s, 6H), 2.1 (m, 2H). 13C NMR
(CDC13) d 147.3, 136.6, 136.3, 132.1, 130.5, 130.0, 129.8, 129.5,
128.1, 126.7, 126.2, 129.9, 56.0, 43.3, 41.9, 34.9, 32.1.
4.1.1.10. Synthesis of 3-bromomethyl-l-(3,4-dichlorophenyl)-
1,2,3,4-tetrahydronaphthalene (15). To a solution of compound
14 (1.25 g, 4.07 mmol) and CBr4 (2.33 G, 7.04 mmol) in CH2C12
(15 mL) was added Ph3P (1.82 g, 6.92 mmol) in CH2C12 (15 mL)
at 0 °C. The reaction was allowed to warm to room temperature
overnight, then poured into water (40 mL), extracted with CH2Cl2
(75 mL), dried over Na2SO4, and the solvent was evaporated. The
residue was purified by chromatography, CombiFlash silica gel col-
umn, EtOAC hexanes, EtOAc from 0% to 15%, to give compound 15
as a clear oil (mixture of cis and trans diastereomers, 1.50 g, 99%).
1H NMR: (CDC13) d 1.52–1.62 (m) and 1.97–2.15 (m, total 2H),
2.25–2.30 (m, 1H), 2.64–2.77 (m, 1H), 3.02–3.12 (m, 1H), 3.34–
3.47 (m, 2H), 4.08 (dd, J = 12 Hz, 5.2 Hz) and 4.26 (t, J = 3.6 Hz, total
1H), 6.72–7.39 (m, 7H). 13C NMR (CDC13) d 31.8, 34.6, 35.6, 36.8,
37.2, 39.2, 39.3, 39.4, 43.3, 46.4, 126.5, 126.8, 126.9, 127.2, 128.3,
128.4, 128.6, 129.0, 129.4, 129.5, 129.7, 130.2, 130.5, 130.7,
130.9, 132.5, 132.8, 136.1, 136.3, 138.3, 147.0, 147.5.
4.1.1.6.2.
cis-Isomers 11c and 11d. LC–MS Rt = 9.1 min,
m/z = 320 (M+1). 1H NMR (CDC13) d 7.4–6.7 (m, 7H), 4.07 (dd,
J = 5.3, 12.2 Hz, 1H), 3.1–2.9 (m, 2H), 2.80 (ddt, J = 2.5, 4.9,
11.4 Hz, 1H), 2.37 (s, 6H), 2.3 (m, 1H), 1.65 (q, J = 12.2 Hz, 1H).
13C NMR (CDC13) d 146.9, 138.0, 136.3, 132.4, 130.6, 130.5,
130.3, 129.5, 129.0, 128.1, 126.4, 126.1, 60.3, 46.4, 41.4, 36.8, 32.8.
4.1.1.7. Synthesis of 4-(3,4-dichlorophenyl)-1-oxo-1,2,3,4-tetra-
hydro-naphthalene-2-carboxylic acid ethyl ester (12). To a stir-
red suspension of NaH (60% dispersion in mineral oil, 1.69 g,
42 mmol) in THF (80 mL) under N2 was added dropwise diethylcar-
bonate (4.85 mL, 40 mmol) at room temperature, followed by 4-
(30,40-dichlorophenyl)-3,4-dihydro-l-(2H)-naphthalone
4 (5.82 g,
4.1.1.11. Synthesis of 3-azidomethyl-l-(3,4-dichlorophenyl)-
1,2,3,4-tetrahydronaphthalene (16). A mixture of compound 15
(0.293 g, 0.79 mmol) and sodium azide (0.154 g, 2.38 mmol) in
DMF (5 mL) was stirred at 60 °C for 24 h. The reaction mixture
was filtered and evaporated in vacuo. The residue was partitioned
between water and EtOAc. The organic layer was separated,
washed with water, dried over Na2SO4, and evaporated to give
compound 16 as a pale-yellow oil (mixture of cis and trans diaste-
reomers, ratio = 1:1.1, 0.18 g, 68%). The diastereomers were sepa-
rated using a preparative chiral HPLC procedure (ChiralPak OD
20 mmol) in THF (20 mL). The mixture was refluxed for 48 h, then
cooled to 0 °C. Acetic acid (10 mL) was added dropwise, and the
mixture was extracted with Et2O. The Et2O extracts were washed
with saturated NaHCO3 solution, brine, dried over MgSO4, and
evaporated. The residue was purified by chromatography, Combi-
Flash silica gel column (hexane/CH2C12 = 50:50) to give compound
12 as a clear oil (5.81 g, 80%). 1H NMR (CDC13) d 1.30 (t, J = 7.2 Hz,
3H), 2.77 (dd, J = 16 Hz, 9.6 Hz, 1H), 2.91 (dd, J = 15.6 Hz, 6.4 Hz,
1H), 4.10 (dd, J = 12 Hz, 6.4 Hz, 1H), 4.19–4.30 (m, 2H), 6.87 (d,
J = 6.8 Hz, 1H), 7.00 (dd, J = 8.4 Hz, 2.0 Hz, 1H), 7.27–7.36 (m, 5H),
7.89 (dd, J = 8.4 Hz, 2.0 Hz, 1H), 12.50 (s, 1H). 13C NMR (CDC13) d
14.5, 29.1, 43.4, 61.0, 95.6, 125.0, 127.6, 127.9, 128.1, 130.2,
130.6, 130.7, 131.0, 131.3, 132.8, 140.4, 143.9, 164.8, 172.6.
column; hexanes/MeOH = 98:2;
l = 8 mL/min; and k = 225 nm) to
give compounds 16a–d (retention times: 9.8 min, 12.0 min,
14.5 min and 20.1 min, respectively).
4.1.1.11.1. cis-Isomers 16a and 16b. 1H NMR (CDC13) d 1.92–
2.09 (m, 3H), 2.61 (dd, J = 16.4 Hz, 9.8 Hz, 1H), 3.00 (dd,
J = 16.8 Hz, 4.8 Hz, 1H), 3.29 (d, J = 6.0 Hz, 2H), 4.25 (t, J = 4.8 Hz,
1H), 6.81–6.92 (m, 2H), 7.08–7.15 (m, 2H), 7.18–7.21 (m, 2H),
7.32 (d, J = 6.0 Hz, 1H). 13C NMR (CDC13) d 30.2, 33.4, 35.5, 43.2,
56.8, 126.6, 127.2, 128.3, 128.9, 129.6, 130.4, 130.5, 130.8, 132.5,
136.2, 136.6, 147.5.
4.1.1.8. Synthesis of 4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-
naphthalene-2-carboxylic acid ethyl ester (13). To a solution of
12 (2.81 g, 7.74 mmol) in TFA (30 mL) was added dropwise Et3SiH
(7.42 mL, 46.44 mmol) at 0 °C. Stirring was continued at 0 °C for
2 h. Then, the solvent was evaporated, and the residue was purified
by chromatography, CombiFlash silica gel column, hexane/CH2C12,
CH2C12 from 0% to 50%, to give compound 13 as a clear oil (mixture
of cis and trans diastereomers, 2.63 g, 97%). 1H NMR (CDC13) d
1.18–1.34 (m, 3H), 1.88 (dd, J = 25.2 Hz, 12.4 Hz) and 2.14–2.19
(m, total 1H), 2.25–2.33 (m) and 2.43–2.55 (m, total 1H), 2.67–
2.74 (m) and 2.82–2.92 (m, total 1H), 3.00–3.18 (m, 2H), 4.08–
4.29 (m,, 3H), 6.72–7.42 (m, 7H).
4.1.1.11.2. trans-Isomers 16c and 16d. 1H NMR (CDCl3) d 1.53
(dd, J = 24.8 Hz, 12.4 Hz, 1H), 2.13–2.25 (m, 2H), 2.67–2.74 (m,
1H), 2.94–3.00 (m, 1H), 3.32–3.41 (m, 2H), 4.08 (dd, J = 12 Hz,
5.2 Hz, 1H), 6.74 (d, J = 12.4 Hz, 1H), 7.00–7.08 (m, 2H), 7.14–7.18
(m, 2H), 7.27 (d, J = 7.8 Hz, 1H), 7.38 (d, J = 12.4 Hz, 1H). 13C NMR
(CDC13) d 34.3, 35.4, 38.3, 46.2, 57.3, 126.5, 126.8, 128.4, 129.4,
129.6, 130.6, 130.7, 130.8, 132.7, 136.0, 138.4, 147.1.
4.1.1.9. Synthesis of [4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-
naphthalen-2-yl]-methanol (14). A solution of 13 (2.55 g,
7.3 mmol) in THF (40 mL) was added dropwise to a stirring mix-
ture of LiAlH4 (0.304 g, 8.0 mmol) in THF (20 mL) at 0 °C. The
resulting suspension was stirred at room temperature for 3 h, then,
the mixture was cooled to 0 °C, and water (0.15 mL) was added
dropwise to destroy the excess hydride. The mixture was filtered,
and the solvent was evaporated in vacuo to give a colorless oil.
The residue was purified by chromatography, CombiFlash silica
gel column, MeOH/CH2C12, MeOH from 0% to 3%, to give Com-
pound 14 as a clear oil (mixture of cis and trans diastereomers,
4.1.1.12. Synthesis of (4-(3,4-dichlorophenyl)-1,2,3,4-tetra-
hydronaphthalen-2-yl)methanamine (17a–d). To a solution of
compound 16a (36 mg, 0.108 mmol), in EtOH (5 mL) was added
Pd/C (10%, 13 mg). A hydrogen balloon was attached and the reac-
tion mixture was stirred at room temperature for 15 min. The mix-
ture was filtered and concentrated in vacuo. The residue was
purified by HPLC, AD column, hexanes/IPA/DEA = 90:10:0.05. Com-
pound 17a was obtained as a clear oil (23 mg, 70%).
Compound 17b was prepared from compound 16b (32 mg,
0.096 mmol) according to the procedure outlined above and was
obtained as a clear oil (19 mg, 63%). LRMS m/z 306.2.

674
L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
Compound 17c was prepared from compound 16c (33 mg,
0.099 mmol) following the procedure outlined above and was ob-
tained as a clear oil (26 mg, 86%).
Compound 17d was prepared from 16d (32 mg, 0.096 mmol)
following the procedure outlined above and was obtained as a
clear oil (20 mg, 70%). LRMS m/z 306.2.
Absolute stereochemistries for compounds 14a–d were deter-
mined using a combination of NMR techniques (determination of
cis- and trans-configurations) and chiral HPLC analyses using
2.47–2.56 (m, 3H), 3.21 (dd. J = 12.6 Hz, 2.7 Hz, 1H), 4.23 (t,
J = 3.6 Hz, 1H), 6.81–6.91 (m, 2H), 7.07–7.12 (m, 2H), 7.16–7.20
(m, 2H), 7.29 (d, J = 6.0 Hz, 1H). 13C NMR (CDC13) d 29.6, 34.5,
36.4, 37.1, 43.5, 58.0, 126.4, 126.9, 127.3, 128.4, 129.6, 130.0,
130.2, 130.5, 132.4, 137.1, 137.2, 148.0. LRMS m/z 320.3.
4.1.1.13.2. cis-Diastereomers 18c and 18d. HRMS [M+H]+: calcd
for (18c) C18H20Cl2N 320.0967, found 320.0994, calculated for
(18d) C18H20Cl2N 320.0967, found 320.0976; 1H NMR (CDC13) d
1.35 (br s, 1H), 1.47 (dd, J = 24.9 Hz, 12.3 Hz, 1H), 2.03–2.13 (m,
1H), 2.17–2.24 (m, 1H), 2.48 (s, 3H), 2.58–2.67 (m, 2H), 2.94–
3.11 (m, 1H), 4.06 (dd, J = 12 Hz, 5.2 Hz, 1H), 6.73 (d, J = 12.4 Hz,
1H), 6.97–7.05 (m, 2H), 7.09–7.18 (m, 2H), 7.26 (d, J = 7.8 Hz,
1H), 7.35 (d, J = 12.4 Hz, 1H). 13C NMR (CDC13) d 35.2, 35.3, 37.1,
39.3, 46.5, 58.5, 126.3, 126.6, 128.5, 129.5, 129.6, 130.3, 130.7,
130.9, 132.6, 137.2, 139.0, 147.6. LRMS m/z 320.3.
authentic samples, which were prepared from commercial (S)-a-
tetralone as described in the text. The resulting structures indicat-
ing absolute stereochemistries are shown below:
NH2
NH2
NH2
NH2
4.1.1.14. Synthesis of [4-(3,4-dichlorophenyl)-1,2,3,4-tetrahy-
dro-naphthalen-2-ylmethyl]-dimethylamine (19a, 19b). A mix-
ture of compound 15 (0.40 g, 1.08 mmol) and dimethylamine (2.0 M
in THF, 5.4 mL, 10.8 mmol) in a scaled tube was heated to 100 °C for
5 h. The reaction mixture was evaporated in vacuo. The residue was
purified by chromatography, CombiFlash silica gel column, MeOH/
CH2C12, MeOH from 0% to 5%, to give 16 as a clear oil (mixture of
cis and trans diastereomers, ratio = 1:1.2, 0.253 g, 70%). cis- and
trans-Diastereomers were separated using a preparative HPLC
procedure (ChiralPak OD column; hexanes/EtOH/MeOH/
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
17a
17b
17c
17d
4.1.1.12.1. cis-Isomers 17a and 17b. 1H NMR (CDC13) d 1.75–
1.97 (m, 3H), 2.51 (dd, J = 16.8 Hz, 9.8 Hz, 1H), 2.61–2.70 (m, 2H),
3.02 (dd, J = 16.8 Hz, 5.2 Hz, 1H), 4.24 (t, J = 3.6 Hz, 1H), 6.81-
6.91 (m, 2H), 7.07–7.12 (m, 2H), 7.16–7.20 (m, 2H), 7.29 (d,
J = 6.0 Hz, 1H). 13C NMR (CDC13) d 32.5, 33.8, 35.8, 43.5, 47.8,
126.4, 127.0, 128.4, 129.6, 130.1, 13 0.2, 130 5, 130.9 132.4,
137.1, 148.1. LRMS m/z 306.2.
DEA = 96:2:2:0.05;
l = 8 mL/min; and k = 225 nm) to give a mixture
4.1.1.12.2. trans-Isomers 17c and 17d. 1H NMR (CDC13) d 1.45
(dd, J = 24.9 Hz, 12.3 Hz, 1H), 1.92–2.00 (m, 1H), 2.18–2.24 (m,
1H), 2.58–2.62 (m, 1H), 2.69–2.80 (m, 2H), 2.94–3.01 (m, 1H),
4.06 (dd, J = 12 Hz, 5.2 Hz, 1H), 6.72 (d, J = 12.4 Hz, 1H), 6.99–7.05
(m, 2H), 7.13–7.18 (m, 2H), 7.27 (d, J = 7.8 Hz, 1H), 7.36 (d,
J = 12.4 Hz.: 1H). 13C NMR (CDC13) d 34.7, 38.2, 38.7, 46.5, 48.2,
126.3, 126.6, 128.4, 129.4, 129.5, 130.4, 130.7, 130.8, 132.7,
136.9, 138.9, 147.6. LRMS m/z 306.2.
of cis-enantiomers (19a) and a mixture of trans-enantiomers (19b).
4.1.1.14.1. cis-Diastereomers 19a. 1H NMR (CDC13) d 1.42 (dd,
J = 24.9 Hz, 12.3 Hz, 1H), 2.03–2.13 (m, 1H), 2.15–2.22 (m, 3H),
2.23 (s, 6H), 2.51–2.61 (m, 1H), 2.94–3.10 (m, 1H), 4.06 (dd,
J = 12 Hz, 5.2 Hz, 1H), 6.73 (d, J = 12.4 Hz, 1H), 6.97–7.05 (m, 2H),
7.09–7.18 (m, 2H), 7.26 (d, J = 7.8 Hz, 1H), 7.35 (d, J = 12.4 Hz,
1H). 13C NMR (CDC13) d 33.3, 35.6, 39.7, 46.3, 46.6, 66.6, 126.3,
126.6, 128.5, 129.5, 129.6, 130.3, 130.7, 130.9, 132.6, 137.2,
139.0, 147.7. LRMS m/z 334.3.
4.1.1.13. Synthesis of [4-(3,4-dichlorophenyl)-1,2,3,4-tetrahy-
dro-naphthalen-2-ylmethyl]-methylamine (18a–d). A mixture
of compound 15 (0.342 g, 0.92 mmol) and methylamine (2.0 M in
THF, 4.6 mL, 9.24 mmol) in a sealed tube was heated to 100 °C for
5 h. The reaction mixture was evaporated in vacuo. The residue
was purified by chromatography, CombiFlash silica gel column,
MeOH/CH2Cl2, MeOH from 0% to 5%, to give Compound 18 as a clear
oil (mixture of cis and trans diastereomers, ratio = 1:1.2, 0.201 g,
68%). Compounds18a, 18b, 18c, and 18d were separated using a pre-
parative chiral HPLC procedure (ChiralPak OD column; hexanes/IPA/
4.1.1.14.2. trans-Diastereomers 19b. 1H NMR (CDC13) d 1.82–
2.05 (m, 3H), 2.13 (s, 6H), 2.20–2.25 (m, 2H), 2.50 (dd, J = 12 Hz,
5.2 Hz, 1H), 2.95–3.04 (m, 2H), 4.22 (t, J = 3.6 Hz, 1H), 6.8–1- 6.91
(m, 2H), 7.07–7.12 (m, 2H), 7.16–7.20 (m, 1H), 7.3 (d, J = 6.0 Hz,
1H). 13C NMR (CDC13) d 27.3, 34.6, 36.2, 43.3, 46.0, 65.4, 126.4,
126.9, 127.3, 128.4, 129.6, 130.0, 130.2, 130.5, 132.4, 137.1,
137.2, 148.1. LRMS m/z 334.3.
4.1.1.15. Synthesis of 2-(-1-(3,4-dichlorophenyl)-1,2-dihy-
dronaphthalen-3-yl)acetonitrile (20). To a stirred solution of
diethyl cyanomethyl phosphonate EtO2POCH2CN (0.324 mL,
2 equiv) in THF (2 mL) was added sodium hydride (60 mg, 60% in
oil) in portions. After 30 min, 4-(3,4-dichlorophenyl)-3,4-dihydro-
naphthalen-2(1H)-one (b-tetralone) 8 (291 mg, 1 mmol) was added
as a solution in THF (3 mL). After the mixture was stirred for 2 h at
0 °C, the reaction was quenched with ammonium chloride solution,
extracted with MTBE, dried over sodium sulfate and evaporated. The
residue was separated on silica to give the unsaturated nitrile
(0.24 g, 77%) as a pale-green oil. GC–MS Rt = 14.59 min, m/z = 313
(M+). 1H NMR (CDCl3) d 7.37 (d, J = 8.3 Hz, 1H), 7.3 (m, 2H), 7.2 (m,
2H), 7.00 (dd, J = 2.1, 8.3 Hz, 1H), 6.84 (d, J = 7.4 Hz, 1H), 6.64 (bs,
1H), 4.17 (t, J = 8.1 Hz, 1H), 3.21 (br s, 2H), 2.69 (dd, J = 6.9, 17.3 Hz,
1H), 2.52 (dd, J = 8.4, 17.2 Hz, 1H). 13C NMR (CDCl3) d 143.9, 135.2,
132.9, 132.5, 130.7, 130.5, 130.0, 128.2, 127.7, 127.5, 126.8, 126.4,
116.5, 43.1, 35.1, 25.1.
DEA = 96:10:0.05;
l = 8 mL/min; and k = 225 nm) to give 18a–d
(retention times: 11.2, 14.7, 16.3, and 21.2 min, respectively).
Absolute stereochemistries of compounds 18a–d were deter-
mined using a combination of NMR techniques (determination of
cis- and trans-configurations) and chiral HPLC analyses using
authentic samples, which were prepared from commercial (S)-a-
tetralone as described in the text. The resulting structures indicat-
ing absolute stereochemistries are shown below:
CH3
CH3
CH3
CH3
N
H
N
H
N
H
N
H
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
18a
18b
18c
18d
4.1.1.13.1. trans-Diastereomers 18a and 18b. HRMS [M+H]+:
calcd for (18a) C18H20Cl2N 320.0967, found 320.0975, calculated
for (18b) C18H20Cl2N 320.0967, found 320.0995; LC–MS 1H NMR
(CDC13) d 1.04 (br s, 1H), 1.88–1.97 (m, 3H), 2.39 (s, 3H),
4.1.1.16. Synthesis of 2-(4-(3,4-dichlorophenyl)-1,2,3,4-tetra-
hydronaphthalen-2-yl)acetonitrile. To a solution of the unsatu-
rated nitrile 20 (210 mg, 0.6683 mmol) in 1% wet methanol
(28 mL) was added 5% Pd/C (21 mg). The atmosphere was

L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
675
evacuated under vacuum and refilled with hydrogen from a bal-
loon. The reaction was monitored by HPLC and was stopped after
220 min. The catalyst was removed by filtration (Celite) and the
solvent removed in vacuo. The residue was diluted with DCM
and filtered through an aminopropyl cartridge. The solvent was
stripped to give the intermediate (201 mg, 95%) as a pale-yellow
oil. 1H NMR (CDCl3) d 7.40 (d, J = 8.3 Hz, 1H), 7.3 (m, 1H), 7.2 (m,
2H), 7.1 (m, 1H), 7.02 (dd, J = 2.1, 8.2 Hz, 1H), 6.76 (d, J = 7.7 Hz,
1H), 4.12 (dd, J = 5.4, 12.1 Hz, 1H), 3.06 (ddd, J = 2.4, 4.3, 16.2 Hz,
1H), 2.80 (dd, J = 12.4, 15.6 Hz, 1H), 2.48 (dd, J = 2.6, 6.5 Hz, 2H),
2.3 (m, 2H), 1.66 (q, J = 12.6 Hz, 1H). 13C NMR (CDCl3) d 146.3,
137.6, 135.1, 132.6, 130.6, 130.6, 129.3, 129.0, 128.1, 126.7,
126.6, 118.1, 45.9, 39.6, 35.8, 31.9, 24.2.
4.1.1.20. Synthesis of 1-(3,4-dichlorophenyl)-3,4-dihydronaph-
thalen-2(1H)-one (23). To a stirring solution of b-tetralone (22)
(1.00 g, 6.84 mmol) and Pd(dba)2 (39 mg, 1 mol %) in toluene was
added t-Bu3P (228uL, 10 wt % in hexanes, 1.1%). The solution was
chilled (dry-ice bath) before adding LiHMDS (7.5 mL, 1 M in hex-
anes, 1.1 equiv) followed by 1-bromo-3,4-dichlorobenzene (1 mL,
1.1 equiv). The solution was then allowed to warm to ambient
temperature and heated under microwave radiation for 5 min
(maximum temperature 140 °C). After cooling, the reaction was
quenched with aqueous ammonium chloride and extracted with
MTBE. The organic layer was dried with sodium sulfate, filtered
through Celite, and evaporated. The crude oil was separated on silic
gel to give the title compound (1.45 g, 73%) as a slight brown oil.
This material was assayed as 90% pure. GC–MS Rt = 13.21 min m/
z = 290 (M+). 1H NMR (CDCl3) d 7.37 (d, J = 8.3 Hz, 1H), 7.3–7.2
(m, 3H), 7.17 (d, J = 2.1 Hz, 1H), 6.9 (m, 2H), 4.68 (s, 1H), 3.1 (m,
2H), 2.7 (m, 2H). 13C NMR (CDCl3) d 208.4, 137.7, 136.7, 135.3,
132.7, 131.5, 130.7, 130.5, 129.2, 128.2, 128.1, 127.7, 127.3, 58.6,
37.1, 28.0.
4.1.1.17. Synthesis of 2-(4-(3,4-dichlorophenyl)-1,2,3,4-tetra-
hydronaphthalen-2-yl)ethanamine (21). To a stirring solution
of the nitrile (200 mg, 0.6324 mmol) and THF (8 mL) at ambient
temperature was added borane-THF (4 mL, 6 equiv) dropwise.
After heating in the microwave (maximum temperature 130 °C)
for 5 min, the reaction was cooled, quenched with 6 N HCl, and
washed with MTBE. The aqueous layer was chilled, basicified with
KOH, and extracted with MTBE. The organic layer was evaporated,
diluted with DCM, dried over sodium sulfate, filtered through an
aminopropyl cartridge and evaporated to give amine 21 (101 mg,
50%) as a pale-yellow oil. LC–MS Rt = 9.41 min, m/z = 320 (M+1).
1H NMR (CDCl3) d 7.36 (d, J = 8.2 Hz, 1H), 7.26 (s, 1H), 7.1 (m,
2H), 7.0 (m, 2H), 6.72 (d, J = 7.7 Hz, 1H), 4.05 (dd, J = 5.3, 12.0 Hz,
1H), 2.92 (dd, J = 2.4, 16.4 Hz, 1H), 2.83 (t, J = 7.3 Hz, 2H), 2.60
(m, 1H), 2.1 (m, 1H), 2.0 (M, 1H), 1.6–1.4 (m, 3H). 13C NMR (CDCl3)
d 147.4, 138.5, 137.0, 132.3, 130.6, 130.4, 130.1, 129.3, 129.0,
128.1, 126.2, 125.9, 46.5, 41.0, 40.8, 39.6, 36.9, 32.3.
4.1.1.21. Synthesis of 1-(3,4-dichlorophenyl)-N-methyl-1,2,3,4-
tetrahydronaphthalen-2-amine (24a–d). To a solution of tetra-
lone 23 (400 mg, 1.374 mmol) in THF (10 mL) and methanol
(15 mL) was added methylamine hydrochloride (1.12 g, 10 equiv).
The resultant mixture was stirred at 50 °C. After dissolution
(10 min), sodium cyanoborohydride (6.9 mL, 1 M in THF, 5 equiv)
was added in a single portion. After 20 h, the organic layer was
evaporated, filtered through silica and an aminopropyl cartridge.
The crude oil was then diluted with sodium bicarbonate solution
and extracted with MTBE to give the amine (280 mg, 66%) as a mix-
ture of four stereoisomers (1:1:1:1).
These amines were separated using a Chiracel OD (98:2:0.1
Hex/IPA/DEA) column to give three fractions. The first was pure
E1 (24a); the second was a mixture of E2 and E3; and the third
was pure E4 (24d). The mixture was further separated using a
Chiracel OD (2:3:95:0.1 MeOH/EtOHHex/ DEA) column. The order
of elution of the middle fractions changes between these columns
and was defined based on the OD 98:2:0.1 conditions. Retention
times are summarized in Table 6, below. The relative (cis/trans)
configuration of the compounds was assigned based on 1H NMR
coupling constants; the absolute stereochemistry was assigned
arbitrarily.
4.1.1.18. Enantiomeric separation of 21; synthesis of tert-butyl
2-(4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydronaphthalen-2-
yl)ethylcarbamate. To a solution of the primary amine (100 mg,
0.3122 mmol) in ether (3 mL) was added 10% KOH (1 mL) and
BOC anhydride (136 mg, 2 equiv). After 2 h at ambient tempera-
ture, the solution was extracted with MTBE. The organic phase
was separated and the volatiles removed in vacuo to give the crude
carbamate (208 mg) as a 1:1 mixture with excess BOC anhydride.
Most of the anhydride was removed by washing an MBTE solution
of the crude product with 1 M HCl. This material was separated on
a Chiracel OD semiprep column (90:10:0.1 Hex/IPA/DEA) to give
the fast moving enantiomer (56.2 mg, 50%) and the slow-moving
enantiomer (55.7 mg, 50%). NMR analysis indicated that the
formed enantiomers had cis-configuration. 1H NMR (CDCl3) d
7.36 (d, J = 8.2 Hz, 1H), 7.3 (m, 1H), 7.1 (m, 2H), 7.0 (m, 2H), 6.72
(d, J = 7.7 Hz, 1H), 4.56 (br s, 1H), 4.04 (dd, J = 5.4, 12.0 Hz, 1H),
3.2 (m, 2H), 2.93 (dd, J = 2.6, 16.3 Hz, 1H), 2.60 (dd, J = 12.0,
16.1 Hz, 1H), 2.2 (m, 1H), 1.9 (m, 1H), 1.57 (q, J = 7.1 Hz, 2H),
1.44 (s, 9H). 13C NMR (CDCl3) d 155.9, 147.3, 138.4, 136.7, 132.4,
130.6, 130.4, 130.1, 129.3, 129.0, 128.1, 126.3, 126.0, 46.4, 40.8,
38.1, 37.0, 36.7, 32.3, 28.4.
4.1.1.21.1. cis-Enantiomers 24b (E2) and 24d (E4). LC–MS
Rt = 8.83 min m/z = 306 (M+1). 1H NMR (CDCl3)
d 7.31 (d,
J = 8.3 Hz, 1H), 7.2–7.1 (m, 3H), 7.1–7.0 (m, 1H), 6.9 (m, 2H), 4.32
(d, J = 5.1 Hz, 1H), 3.1–2.8 (m, 3H), 2.50 (s, 3H), 1.9 (m, 1H), 1.6
(m, 1H). 13C NMR (CDCl3) d 142.5, 137.4, 136.4, 132.0, 131.9,
130.5, 129.7, 129.6, 128.8, 126.7, 126.0, 58.5, 48.3, 33.9, 28.1, 23.7.
4.1.1.21.2. trans-Enantiomers 24a (E1) and 24c (E3). LC–MS
Rt = 9.12 min m/z = 306 (M+1). 1H NMR (CDCl3)
d 7.37 (d,
J = 8.2 Hz, 1H), 7.2 (m, 1H), 7.1 (m, 2H), 7.0 (m,1H), 6.97 (dd,
J = 2.0, 8.2 Hz, 1H), 6.69 (d, J = 7.8 Hz, 1H), 3.91 (d, J = 7.7 Hz, 1H),
2.94 (t, J = 6.5 Hz, 2H), 7.51 (td, J = 1.4, 7.5 Hz, 1H), 2.42 (s, 3H),
2.2 (m, 1H), 1.7 (m, 1H). 13C NMR (CDCl3) d 145.1, 137.0, 136.4,
132.5, 131.4, 131.4, 130.8, 130.0, 129.9, 128.4, 126.7, 126.0, 62.3,
51.4, 33.7, 27.1, 25.5.
4.1.1.19. Synthesis of cis and trans-2-(1-(3,4-dichlorophenyl)-
1,2,3,4-tetrahydronaphthalen-3-yl)acetonitrile (21a and 21b). To
a solution of carbamate (20 mg, 0.05585 mmol) in CDCl3 was
added HCl (1 mL, 4 M in dioxane). After 1 h, the mixture was
chilled, quenched with KOH (1 mL, 5 M in H2O), extracted with
MTBE and evaporated. The crude oil was diluted in DCM, filtered
through an aminopropylcartridge and evaporated to give the pure
primary amine 21a (11.5 mg, 64%) as a clear oil.
Table 6
Retention times for each isomer [min]
24a
E1
24b 24c
E2 E3
24d
E4
trans cis
trans cis
HPLC Rt (Chiracel OD, 98:2:0.1 Hex/IPA/DEA)
HPLC Rt (Chiracel OD, 2:3:95:0.1 MeOH/EtOH/
Hex/DEA)
6.0
5.5
6.7
6.2
7.9
7.0
13.7
10.5
The second enantiomer was prepared from the enantiomeric
carbamate using the procedure described above to give the enan-
tiomeric amine 21b (11.1 mg, 62%) as a clear oil.

676
L. Shao et al. / Bioorg. Med. Chem. 19 (2011) 663–676
4.2. In vitro pharmacology
with infrared photocell beams to measure movement of the ani-
mals. Horizontal and vertical activities were measured.
Rats or mice were pretreated with vehicle or test compounds
and placed back in home cage, following which they were individ-
ually placed in locomotor cages and activity was monitored in
5 min intervals for up to 60 min.
The novel compounds described above were tested for their
inhibition of functional uptake of 5-HT,14 NE,15 or DA,16 using re-
combinant transporters expressed in HEK-293, MDCK or CHO-K1
cells as described in the literature. Compounds were tested initially
at 10
l
M in duplicate, and if P50% inhibition of uptake was ob-
Data were analyzed by one way analysis of variance (ANOVA)
followed by post-hoc comparisons where appropriate. An effect
was considered significant if p <0.05.
served, they were tested further at 10 different concentrations in
duplicate in order to obtain full inhibition curves. IC50 values (con-
centration inhibiting control activity by 50%) were then deter-
mined by nonlinear regression analysis of the inhibition curves.
Assay performance was monitored by the use of SERT reference
compound fluoxetine (IC50 = 5.2 0.6 nM), NET reference com-
pound nisoxetine (IC50 = 8.3 1.0 nM) and DAT reference com-
pound nomifensine (IC50 = 30.2 2.2 nM). Replicate studies done
independently on a set of compounds allowed the determination
of values for minimum significant ratios (MSR). MSR is a statistical
measure for how many fold different IC50 values for two com-
pounds (determined only once) must be for those two IC50 values
to be considered significantly different with 95% confidence lim-
its.20 From replicate studies of the effects of 13 reuptake inhibitors
assayed with the human transporters at MDS Pharma on two sep-
arate occasions, MSR values were 2, 2, and 3, respectively, for SERT,
NET and DAT. Similar analysis of the assays performed internally at
Sepracor provided MSR values of 4, 3, and 2, respectively, for SERT,
NET, and DAT. These corresponded to average SD values (on pIC50s)
of 0.2–0.3.
Acknowledgements
The authors thank Zhi-Dong Jiang and Margaret E. Kearney for
their technical support.
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In order to ensure effects of the compounds on immobility time
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activity, locomotor activity was assessed using photocell moni-
tored cages (Med-Associates Inc.). Each test chamber was equipped