N1,N1-dimethyl-N3-(3-(trifluoromethyl) phenethyl)propane-1,3-diamine, a new lead for the treatment of human African trypanosomiasis

Article abstract of DOI:10.1016/j.ejmech.2013.12.050

The natural product, convolutamine I (1), has anti-trypanosomal activity however it has a high molecular weight of 473 due to a presence of 3 bromine atoms. The synthesis of the natural product convolutamine I (1) together with its analogues are presented. A SAR study against Trypanosoma brucei brucei led to compounds with improved physico-chemical properties: lower molecular weight and lower log P while maintaining potency (with a slight 2-fold improvement).

Full text of DOI:10.1016/j.ejmech.2013.12.050

European Journal of Medicinal Chemistry 74 (2014) 541e551
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
N1,N1-Dimethyl-N3-(3-(trifluoromethyl)phenethyl)propane-
1,3-diamine, a new lead for the treatment of human African
trypanosomiasisq
Ngoc B. Pham a, Sophie Deydier a, Mehdi Labaied b, Séverine Monnerat b, Kenneth Stuart b,
,
Ronald J. Quinn a
*
a Eskitis Institute for Drug Discovery, Griffith University, Nathan Campus, Brisbane, Queensland 4111, Australia
b Seattle BioMed, 307 Westlake Ave. N, Seattle, WA 98109-5219, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
The natural product, convolutamine I (1), has anti-trypanosomal activity however it has a high molecular
weight of 473 due to a presence of 3 bromine atoms. The synthesis of the natural product convolutamine
I (1) together with its analogues are presented. A SAR study against Trypanosoma brucei brucei led to
compounds with improved physico-chemical properties: lower molecular weight and lower log P while
maintaining potency (with a slight 2-fold improvement).
Received 7 September 2013
Received in revised form
25 November 2013
Accepted 22 December 2013
Available online 9 January 2014
Ó 2014 The Authors. Published by Elsevier Masson SAS. All rights reserved.
Keywords:
Alkaloids
Anti-parasite
Anti-protozoa
Human African trypanosomiasis
1. Introduction
or fatal (3e10%) side effects, resistance is developing and there is a
failure rate of up to 30% [2]; eflornithine which is less toxic, has
Human African trypanosomiasis, also known as African
sleeping sickness, is endemic in the regions of sub-Saharan Africa,
affecting around 70 million people in 36 countries [1]. The disease
is caused by protozoa of the species Trypanosoma brucei and
transmitted through the bite of an infected tsetse fly or passed
from mother to child as the parasite can pass the placenta and
infect the foetus. At the early stage, the trypanosomes multiply in
subcutaneous tissues, blood and lymph and patients develop
insignificant symptoms such as fever, headaches, joint pains and
itching. In time, the parasites cross the bloodebrain barrier and
infect the central nervous system and patients start to develop
confusion, sensory disturbances, poor coordination and sleep cycle
disturbance. Without treatment, African sleeping sickness is fatal
[1]. Current treatment for the neurological stage includes mel-
arsoprol, an arsenical derivative known to have many undesirable
compliance issues and is only effective against the Trypanosoma
brucei gambiense subspecies [3]; or a combination treatment of
nifurtimox and eflornithine which is less toxic but not effective
against the Trypanosoma brucei rhodesiense subspecies [1]. New,
safe and effective drugs are urgently needed. As part of a
continuing study for novel entities with high efficacy and less
toxicity for human African trypanosomiasis, we have previously
described the active natural product, convolutamine I (1), isolated
from the bryozoan Amathia tortusa [4]. In order for a new drug to
combat human African trypanosomiasis at the late stage of the
disease, the active drug should be able to pass bloodebrain barrier.
Analyses of central nervous system (CNS) drugs [5,6] showed CNS
drugs have molecular weight (MW) in the range from 141 to 452,
clogP from ꢀ0.66 to 6.1 and topological polar surface area (tPSA)
from 3.2 to 97 Å2. Combined analyses of CNS drugs and drug
candidates have provided guidelines on these physico-chemical
properties [5,6], such as 250 < MW < 355, 1.5 < clogP < 2.7, and
25 < tPSA < 60. In this paper we present a synthetic route to
convolutamine I (1) and a series of analogues designed to lower
MW, clogP and keep tPSA in the CNS drug range while maintaining
activity.
q
This is an open access article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/3.0/).
* Corresponding author. Tel.: þ61 7 3735 6009; fax: þ61 7 3735 6001.
E-mail address: r.quinn@griffith.edu.au (R.J. Quinn).
0223-5234/$ e see front matter Ó 2014 The Authors. Published by Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.ejmech.2013.12.050

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N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
Scheme 1. Synthesis of 1. Reagent and conditions: (a) Br2, H2O, rt, 3 days, 65% yield; (b) MeI, K2CO3, DMF, rt, 65% yield; (c) (i) ClCH2COOEt, NaOEt, dry toluene, (ii) NaOH 30%, (iii)
HCl con., reflux, 13% yield; (d) NH2(CH2)3NMe2, NaBH4/K10, microwave, 10 min, 56% yield, (e) Br2, AcOH/HCl, 80 ꢁC, 85% yield; (f) 3-chloro-N,N-dimethylpropan-1-amine, H2O/
CH2Cl2, 140 ꢁC, 10 min, 60% yield.
2. Results and discussion
397 [M þ H]þ, indicative of two bromine atoms. The 1H NMR
spectrum of 25 shows two aromatic protons at dH 7.65 (s, 1H) and
6.78 (s, 1H), a methoxyl signal at 3.84 (s, 3H), a tripletepentete
triplet pattern for the 1,3-disubstibuted propane unit (NHReCH2e
CH2eCH2eN(Me)2) at dH 2.27 (t, J ¼ 7.2 Hz, 2H), 1.65 (p, J ¼ 7.1 Hz,
2H) and 2.67 (t, J ¼ 7.1 Hz, 2H), a four proton multiplet for the di-
substituted ethane unit at dH 2.84e2.86 (m, 4H), and an N-methyl
signal for 2 eq. methyl groups at dH 2.17 (6H, s). The g-COSY cor-
relations confirm the assignment of the dH 2.27, 1.65, 2.67 to the
NHReCH2eCH2eCH2eN(CH3)2 substructure. The HSQC allows the
assignment of all protons to their directly attached carbons, con-
firming one aromatic proton flanked by two bromine atoms with a
downfield proton chemical shift (dH 7.65) and a downfield carbon
chemical shift for its attached carbon (dC 136.2). The structure
elucidation for 25 is completed with HMBC correlations of the 2 eq.
N-methyl groups at dH 2.17 (s, 6H) to the terminal carbon (dC 58.0)
of the propane unit (NHReCH2eCH2eCH2eN(CH3)2), the proton of
propane unit (dH 2.67) to the second carbon (dC 49.4) of the ethane
unit and the proton of the ethane unit (dH 2.86) to carbons (dC 139.9,
115.0 and 113.9) of the aromatic ring. Compound 26 was distin-
guished from 25 by the two aromatic proton signals at dH 7.47 and
6.67 with a typical coupling constant of 8.8 Hz for two adjacent
aromatic protons. The carbon bearing the proton dH 6.67 had the
chemical shift of dC 111.2, confirming its position being adjacent to
the methoxy bearing carbon and 2,6-dibromo substitutions in the
aromatic ring.
The alkylation reactions were first performed in NaH/DMF or
THF, however this led to multi-alkylated products rather than
mono-alkylated products. Milder basic conditions such as trie-
thylamine in chloroform/ethanol [10], or NaHCO3, SDS in water at
80 ꢁC [11], or Cs2CO3 in DMF at rt [12], failed to produce products.
In the past few years, microwave assisted reactions have been
employed and have successfully delivered high yield, clean
products with short reaction times. The efficiency of microwave
irradiation over the conventional thermal process lies in its
uniform heat delivery to all reactants in a closed reaction vessel.
Monitored with LCeUVeMS for the formation of convolutamine I
(1), the N-alkylation reaction gave the best yield in water/chlo-
roform at 70:30 or 90:10 ratio depending on water solubility of
reagents, at pH10 using sodium hydroxide 2 M, and a microwave
temperature at 140 ꢁC for 10 min. We also found that product
yield was the same if we used sodium hydroxide or triethylamine
for pH adjustment, however the partition purification step was
more efficient if sodium hydroxide was used. Under these opti-
mized conditions, mono-alkylated and di-alkylated products
were obtained in a ratio of 2:1 or 3:1 (mono-alkylation:di-
alkylation) while tri-alkylated amines were not formed as
monitored by LCeUVeMS. If the reaction temperature was
increased to 150 ꢁC or 160 ꢁC, the percentage of di-alkylated
product was also increased.
2.1. Chemistry
Convolutamine I (1) was synthesized by two different routes in
order to facilitate analogue development. In the first route, 3-
hydroxybenzaldehyde (2) was brominated [7] to give the bromi-
nated aldehyde (3) that was then treated with methyl iodide in
DMF in the presence of K2CO3 to give the methoxy brominated
benzaldehyde (4). Carbonecarbon elongation of 4 was performed
via Darzens condensation to give 5 which was subsequently
condensed with N1,N1-dimethylpropane-1,3-diamine in the pres-
ence of mixture of NaBH4 and clay K10 under microwave irradiation
[8] to give 1 (Route 1, Scheme 1).
In the second synthetic route, 3-methoxy phenylethanamine (6)
was brominated in the presence of bromine in acetic acid to give
the 2-,4-,6-tribromo derivative (7). A dimethylaminoethyl side
chain was introduced to 7 by an N-alkylation reaction [9] with alkyl
chloride to give convolutamine I (1) (Route 2, Scheme 1). NMR data
of 1 was consistent with the isolated natural product [4].
Analogues 8, 9, 12, 13, 17, 18 with a one carbon shorter chain
between the phenyl group and the first nitrogen compared to 1
were synthesized by brominating 3-hydroxybenzaldehyde or 4-
hydroxybenzaldehyde and condensation with N1,N1-dimethylpro-
pane-1,3-diamine according to Scheme 2. Compounds 19e22
(Table 1) were synthesized in an analogous route without the
bromination step. The carbon NMR data for this series with 11
distinct signals confirmed one carbon shorter in the side chain of
these analogues. Compounds 8 and 9 had (þ)-LRESIMS 1:3:3:1
cluster of ions indicative of 3 bromine atoms. 8 and 9 had one ar-
omatic proton signal at dH 7.60 and 7.96, respectively, and three
upfield quaternary carbon signals at 105e120 ppm, confirming a
three-bromine-substituted aromatic ring. Compounds 12 and 13
had two singlet aromatic protons para to each other at dH 7.53, 6.86
and 7.73, 7.21, respectively, and two diagnostic quaternary bromi-
nated carbon signals at dC 105e120, confirming a 2,4-dibromo
substituted aromatic ring. Compound 18 had one aromatic signal
at dH 7.63 assigned to 2 eq. protons; its attached carbon had a
chemical shift of dC 133.8, confirming a 2,5-dibromo-4-methoxy
substituted aromatic ring.
Analogues with 2 bromine substituents (25, 26) or no bromine
(29) were synthesized following the reaction sequence of Scheme
2. To achieve a 2 bromine-substituted phenethylamine, a less
acidic condition and a lower reaction temperature (60 ꢁC) were
used (Scheme 3). The intermediates 23 and 24 were used as a
mixture in the N-alkylation step. The mixture of products 25 and 26
was purified and separated by reversed-phase HPLC. All final
compounds and intermediates were fully characterized by the
usual spectroscopic methods (see Experimental section). The
(þ)-LRESIMS of 25 revealed a 1:3:1 cluster of ions at m/z 393/395/

N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
543
Scheme 2. Synthesis of 8e18. Reagent and conditions: a) Br2, AcOH/HCl, 80 ꢁC, 85% yield; (b) Br2, CHCl3, rt, 3 days, 70% yield; (c) Br2, AcONa/AcOH, rt, 1 h, 90% yield; (d) MeI, K2CO3,
DMF, rt, 46e93% yield; (e) NH2(CH2)3NMe2, NaBH4/K10, microwave, 10 min, 56e75% yield.
Compound 30 was synthesized via N-alkylation of 25 with 3-
chloroprop-1-yne under microwave irradiation. Compound 31
was synthesized by reacting 25 with acetyl chloride in chloroform
basified with NaOH. Analogues without the nitrogen terminal
group (32e35) were synthesized using an N-alkylation of inter-
mediate brominated phenethylamine 23. Compound 36 was a
cyclization product of the N-alkylation reaction of 23 and 4-
chlorobut-1-yne under microwave irradiation at 200 ꢁC for
15 min. Compounds with different ring systems were synthesized
in the same reaction sequence as in Scheme 2. Commercial 2-
(naphthalen-2-yl)ethanamine, 2-(pyridin-3-yl)ethanamine, 2-(thi-
loss of activity, indicating that bromine atoms at positions C-4 and
C-6 are important.
Compounds 25e29 investigated the importance of bromine
atom at position C-2, C-4 and C-6 for analogues having a 2-carbon
side chain between the phenyl group and the first nitrogen. Results
showed that 25, with a loss of a bromine atom at C-2, displayed an
increase in activity (IC50 0.3 mM). A complete removal of bromine
atoms resulted in a loss of activity (29). Other rearrangements of
bromine and methoxy groups on the phenyl group were not
effective in retaining activity. As activity was retained by removing
the bromine at C-2, this substitution was retained in the next series
of analogues.
ophen-2-yl)ethanamine,
(2,3-dihydro-1H-inden-2-yl)methan-
amine were treated with 3-chloro-N,N-dimethylpropan-1-amine to
give 37e40. A series of analogues with different substituted groups
on the phenyl group were synthesized in the same reaction
sequence as in Scheme 2 to give 27e29, 41e55 (Fig. 1).
An acetamide or a propyne attached to the first nitrogen aimed
at a reduction of basicity (30, 31) led to a loss of activity. Replacing
the second basic terminal nitrogen with a non-basic terminal group
such as a hydroxy (33), or other terminal alkyne groups (34, 35) led
to a loss of activity. However, replacement with a eNH2 group (32)
2.2. Anti-trypanosomal activity
retained activity (IC50 2 mM). The result suggested the side chain
terminal group should be basic. The result supported the finding in
our previous published paper [3] that the terminal tetrahydropyr-
imidinium group of the side chain in convolutamine J caused
The anti-trypanosomal activity of 1, 8, 9, 12, 13, 17e22, 25e55
was evaluated in vitro against T. b. brucei (Table 1). Synthetic con-
volutamine I (1) exhibited potent activity against T. b. brucei with an
reduction in activity (IC50 13.6
mM). Replacing the brominated
IC50 value of 1.1
m
M, comparable to the isolated convolutamine I.
phenyl group by naphthalene, pyridine, thiophene and 2,3-
dihydro-1H-inden-2-amine (37e40) also gave a loss of activity,
suggesting a phenyl group with large electrophilic substitutes was
important.
These results established that the phenyl group and the side
chain containing 2 basic nitrogen atoms were all important. We
then conducted a series of analogues (41e55) with other halogen-
substituted phenyl groups in place of the non drug-like tri- or di-
brominated phenyl group. Walking a bromine atom or a fluorine
atom around the phenyl group produced a loss of activity (41e46).
Compounds 8, 9, 12, 13, 17e22 examined the importance of the
length between the phenyl group and the first nitrogen of the side
chain of convolutamine I in parallel with the importance of
bromine substitution. Reducing the 2-carbon chain in 1 to a 1-
carbon chain led to a loss of activity for tri-brominated 9, but
retained the activity for di-brominated 12, 13. Removal of all
bromine atoms and replacing the methoxy with a hydroxy group
(19, 20) or retaining the methoxy group (21, 22) gave a loss in ac-
tivity. 4-Methoxy/hydroxy 3,5-dibromo compounds (17e18) had a

544
N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
Table 1
Anti-trypanosomal activity.
Compound
Structure
Activity (IC50
1.1
m
M)
MW
clogP
4.05
tPSA
1
473.0
24.50
8
9
>8
>8
445.0
459.0
2.30
3.76
35.50
24.50
12
13
17
2.2
4.6
>8
366.1
380.1
366.1
1.49
2.99
1.65
35.50
24.50
35.50
18
>8
380.1
2.99
24.5
19
20
21
22
25
>8
>8
>8
>8
0.3
208.3
208.3
222.3
222.3
394.1
0.42
0.40
1.45
1.45
3.2
35.50
35.50
24.50
24.50
24.5
26
4-8
394.1
3.28
24.50
27
28
>8
>8
315.2
315.2
2.51
2.51
24.50
24.50
29
30
>8
>8
236.3
432.2
1.74
3.89
24.50
15.71
31
>8
436.2
2.89
32.78

N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
545
Table 1 (continued )
Compound
Structure
Activity (IC50
2.0
m
M)
MW
clogP
2.46
tPSA
32
33
34
366.1
47.28
41.49
21.26
>8
>8
367.1
347.0
2.57
3.43
35
36
>8
>8
361.1
363.1
3.72
3.99
21.26
12.47
37
38
4e8
>8
256.4
207.3
2.89
0.71
15.27
28.16
39
40
>8
>8
212.3
218.3
1.81
2.00
15.27
15.27
41
>8
285.2
2.67
15.27
42
43
>8
>8
285.2
285.2
2.67
2.67
15.27
15.27
44
>8
224.3
1.66
24.06
45
46
>8
>8
224.3
224.3
1.66
1.66
24.06
24.06
47
>8
240.7
2.50
15.27
15.27
48
49
0.7
240.7
240.7
2.50
2.50
>8
15.27
(continued on next page)

546
N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
Table 1 (continued )
Compound
Structure
Activity (IC50
m
M)
MW
clogP
2.35
tPSA
50
51
52
>8
270.8
24.50
>8
>8
275.2
275.2
3.11
3.11
15.27
15.27
53
>8
275.2
3.11
15.27
54
55
>8
258.8
274.3
2.65
2.78
15.27
15.27
0.5
Scheme 3. Synthesis of 25, 26. Reagent and conditions: (a) Br2, AcOH, 60 ꢁC, 2 h, 85% yield; (b) 3-chloro-N,N-dimethylpropan-1-amine, H2O/CH2Cl2, pH10, 140 ꢁC, 10 min, 60% yield.
However, a chlorine atom at C-3 (48) retained activity (IC50 0.7
m
M)
past twenty years a substantial effort has been devoted to the
incorporation of the trifluoromethyl group into prototype mole-
cules due to its known unique chemical and physiological stability.
In most instances, the trifluoromethyl group has been used to
replace a methyl group or a chlorine atom. The main advantage of
trifluoromethyl-substituted aryl compounds is the ability to in-
crease lipid solubility and thereby enhance the rate of absorption
and transport of the drug across the bloodebrain barrier [13].
while a chlorine atom at C-2 (49) or C-4 (50) produced loss of ac-
tivity. Since compound 48 with one chlorine atom gave comparable
activity to compound 25 and convolutamine I (1), the next series of
analogues was made having 2 chlorine atoms or a combination of 1
chlorine and a methoxy group (50e53). The result showed that
more than one chlorine atom was unfavourable to activity.
Since a chlorine substituent a C-3 (48) was important, we
replaced the chlorine with a trifluoromethyl group (55) to explore if
this modification improves the biological properties. During the
Compound 55 had an IC50 of 0.5
mM, which was as potent as 48 and
two-fold more active than the natural product convolutamine I (1).
Fig. 1. Different halogen substitutions on the phenyl group of 1, 25e29 and 41e55.

N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
547
Compounds 48 and 55 had MW of 240.7 and 274.3 and clogP of
4.2. Activity assay e IC50 measurement
2.50 and 2.78 respectively, compared with the natural product MW
of 473.0, clogP of 4.05. Compounds 48 and 55 had physico-chemical
properties in the region of CNS drugs [5]. Their MW, clogP and tPSA
values were close to the preferred lower limit for CNS drugs (MW at
250, clogP at 2.1 and tPSA at 23) [5]. The structureeactivity study
emphasized the importance of the basicity of the nitrogen in the
side chain (Fig. 2) and demonstrated a great improvement on
compound properties since the new active compounds have a
much lower molecular weight, and better log P values and may
allow further analogue development.
IC50s were determined according to Sykes and Avery [14] with
some modifications. Briefly, a starting inoculum of 2 ꢂ 103 T. b.
brucei 427 bloodstream form parasites were incubated with a range
of two-fold serial dilutions drug concentrations in 96-well culture
plates, in a final volume of 200
mL per well (HMI-9 with 10% FBS),
for 48-h at 37 ꢁCe5% CO2. 20
mL of Alamar BlueÔ was then added to
each well before an additional 4-h incubation in the same culture
conditions. Positive control (parasites in absence of drug) and
negative control (absence of both parasites and drug) culture
conditions were included in each plate. Fluorescence signal was
quantified using SpectraMax M2 Multi-mode plate Reader (Ext:
544 e Em: 590). IC50 values were determined using the GraphPad
Prism5 software. Compounds were tested with three biological
replicates and the value of each biological replicate is the average of
three technical replicates.
3. Conclusion
We have identified lead anti-trypanosoma compounds 48 and
55, which have low micromolar activity. Compounds 48 and 55
have improved drug-like properties compared with the lead nat-
ural product convolutamine I (1). The improvements in the drug-
like profile of 48 and 55 are attributed to the replacement of 3
bromines and one methoxy with a chlorine atom or a tri-
fluoromethyl group. The structureeactivity relationships estab-
lished in the course of designing 48 and 55 may be usefully applied
for future design strategies for potent and drug-like compounds
from brominated natural products.
4.3. Typical procedure for bromination reaction
To
a
cooled solution (5 ꢁC) of 3-hydroxybenzaldehyde
(0.409 mmol, 0.500 g) in glacial acetic acid (8.0 mL, 0.14 mol), Br2
(0.12 mL, 2.3 mmol) was added and stirred for 3 h at r.t. After
completion of the reaction, the reaction was quenched with satu-
rated Na2S2O3 solution and the solvent was removed under vacuum
pressure. The reaction mass was then extracted with ethyl acetate.
The organic layer was dried prior to being purified by RP-HPLC
column to give brominated compounds.
4. Experimental protocols
4.1. General
4.4. Typical procedure for reductive amination reaction (microwave
irradiation)
NMR spectra were recorded at 30 ꢁC on a Varian Inova 600 MHz
and 500 MHz spectrometers. The 1H and 13C chemical shift were
referenced to the CD3OD solvent peaks at dH 4.80 and dC 48.1 ppm,
CDCl3 solvent peaks at dH 7.26 and dC 77.0 ppm. Standard param-
eters were used for the 2D-NMR spectra obtained, which included
g-COSY, gHSQC (1JCH ¼ 140 Hz), gHMBC (nJCH ¼ 8.3 Hz). Mass
spectra were acquired using a Waters ZQ. High-resolution mass
measurement was acquired on a Bruker Daltonics Apex III 4.7e
Fourier transform mass spectrometer, fitted with an Apollo API
In a 0.5e2 mL microwave vial were added 5 mg of clay K10,
2,4,6-tribromo-3-methoxy-benzaldehyde (12 mg, 0.031 mmol,
1 eq.), N,N-dimethyl 1,3-propane diamine (4
mL, 0.031 mmol, 1 eq.)
and 100 L of MeOH. The mixture was stirred for 2 min, sealed and
m
then irradiated for 10 min at 65 ꢁC. A mixture of 5 mg of clay K10
with sodium borohydride 95% (1.25 mg, 0.031 mmol, 1 eq.) was
then added to the reaction mixture, it was sealed and irradiated for
5 min at 100 ꢁC. It was then diluted with MeOH, filtered, concen-
trated to dryness and purified by Flash chromatography (silica gel,
DCM/MeOH/NEt3 80/20/0.01) to give 1 (8.5 mg, 58% yield).
source. A Betasil C18 column (5
m
m, 150 ꢂ 21.2 mm) and Hypersil
m, 250 ꢂ 10 mm) were used for semi-
Phenomenex Luna C18 column (3 m,
BDS C18 column (5
preparative HPLC.
m
A
m
4.6 ꢂ 50 mm) was used for LC/MS controlled by MassLynx 4.1
software. All solvents used for chromatography were Omnisolv
HPLC grade and the H2O used was Millipore Milli-Q PF filtered. All
the starting amines and alkyl halides were obtained from Aldrich
Chemical Co. and were used as such.
4.5. Typical procedure for reductive amination reaction
To a stirred solution of 4-methoxy-benzaldehyde (100 mg,
0.734 mmol, 1 eq.) and N,N-dimethyl 1,3-propane diamine (102 mL,
0.808 mmol, 1.1 eq.) in 2 mL of dry DCM was added a small spatula
of Na2SO4. The resulting mixture was stirred at room temperature
for 22 h. When there is no evidence of starting material by TLC, the
reaction mixture was filtered and concentrated to dryness. It was
then dissolved in MeOH (1 mL) and sodium borohydride 95%
(15 mg, 0.367, 0.5 eq.) was added. The reaction mixture was stirred
at room temperature for 96 h and was then concentrated to dryness
and purified by flash chromatography (silica gel, EtOAc/MeOH/NEt3
90/10/0.1 to 50/50/0.1) to give 22 (45.7 mg, 28% yield).
4.6. Typical procedure for N-alkylation
A mixture of substituted phenylethanamine (0.1 mmol), alkyl
chloride (0.12 mmol) in a waterechloroform (70:30, 0.5 mL) and
NaOH in water to reach pH10 (2 M solution) was placed in a mi-
crowave tube (2 mL). The tube was subjected to MW irradiation at
140 ꢁC for 10 min. After completion of the reaction (monitored by
LC/MS), the product was extracted into ethyl acetate. Removal of
Fig. 2. Structureeactivity relationship study of 1.

548
N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
the solvent under reduced pressure, followed by reversed-phase
HPLC chromatography using wateremethanol as eluent in a
gradient system for 60 min afforded final product and confirmed by
satisfactory 1H and 13C or 2D (g-COSY, HSQC, HMBC) NMR spectra.
(125 MHz, CD3OD) 154.3, 140.2, 133.8 (ꢂ2), 118.8 (ꢂ2), 61.0, 58.6,
52.8, 48.0, 45.4 (ꢂ2), 28.0. HRESIMS(þ): m/z calculated
[C13H21N2O1Br2]þ 379.0015, found 379.0020.
4.7.8. 3-(((3-(Dimethylamino)propyl)amino)methyl)phenol (19)
Obtained as a yellow solid, 75% yield; 1H (500 MHz, CD3OD) dH
7.14 (t, J ¼ 8.0 Hz, 1H), 6.77 (m, 2H), 6.69 (d, J ¼ 8.0 Hz, 1H), 3.66 (s,
2H), 2.58 (m, 2H), 2.33 (m, 2H), 2.22 (s, 6H), 1.70 (p, J ¼ 7.5 Hz, 2H).
13C NMR (125 MHz, CD3OD) 159.0, 142.0, 130.4, 120.4, 116.5, 115.2,
58.7, 54.4, 48.1, 45.4 (ꢂ2), 27.9. HRESIMS(þ): m/z calculated
[C12H21N2O1]þ 209.1648, found 209.1649.
4.7. Synthesis of target compounds
4.7.1. N1,N1-Dimethyl-N3-(2,4,6-tribromo-3-methoxyphenethyl)
propane-1,3-diamine (1)
Obtained as a yellow oil, 3% yield (synthetic route 1), 50% yield
(synthetic route 2); 1H (600 MHz, DMSO-d6) dH 7.96 (s, 1H), 3.78 (s,
3H), 3.04 (m, 2H), 2.63 (m, 2H), 2.56 (m, 2H), 2.22 (m, 2H), 2.09 (s,
6H), 1.52 (t, J ¼ 7.5 Hz, 2H). 13C NMR (150 MHz, DMSO-d6) 154.2,
140.8, 135.8, 120.5, 120.0, 115.9, 61.0, 58.2, 48.0, 48.1, 46.1 (ꢂ2), 38.3,
28.3. HRESIMS(þ): m/z calculated for [C14H22N2O1Br3]þ 470.9276,
found 470.9267.
4.7.9. 4-(((3-(Dimethylamino)propyl)amino)methyl)phenol (20)
Obtained as a yellow solid, 75% yield; 1H (500 MHz, CD3OD) dH
7.06 (dd, J ¼ 8.5, 2.3 Hz, 2H), 6.67 (dd, J ¼ 8.5, 2.3 Hz, 2H), 3.56 (s,
2H), 2.51 (t, J ¼ 7.5 Hz, 2H), 2.26 (t, J ¼ 7.5 Hz, 2H), 1.63 (p, J ¼ 7.5 Hz,
2H). 13C NMR (125 MHz, CD3OD) 157.8, 140.9, 129.4 (ꢂ2), 114.5 (ꢂ2),
57.2, 52.5, 46.6, 44.0 (ꢂ2), 26.5. HRESIMS(þ): m/z calculated
[C12H21N2O1]þ 209.1648, found 209.1649.
4.7.2. N1,N1-Dimethyl-N3-(2,4,6-tribromo-3-methoxybenzyl)
propane-1,3-diamine (8)
Obtained as a yellow oil, 60% yield; 1H (500 MHz, CD3OD) dH 7.60
(s, 1H), 4.19 (s, 2H), 2.99 (m, 2H), 2.85 (m, 2H), 2.56 (s, 6H), 1.87 (t,
J ¼ 7.5 Hz, 2H), 13C NMR (125 MHz, CD3OD) 161.5, 135.0, 135.0,119.6,
116.1, 106.0, 59.4, 54.3, 48.5, 44.4 (ꢂ2), 24.8. HRESIMS(þ): m/z
calculated for C12H18N2O1Br3 442.8963 found 442.8966.
4.7.10. N1-(3-Methoxybenzyl)-N3,N3-dimethylpropane-1,3-diamine
(21)
Obtained as a yellow solid, 66% yield; 1H (500 MHz, CD3OD) dH
7.25 (t, J ¼ 8.0 Hz, 1H), 6.95 (s, 1H), 6.92 (d, J ¼ 8.0 Hz, 1H), 6.83 (d,
J ¼ 8.0 Hz, 1H), 3.81 (s, 3H), 3.75 (s, 2H), 2.63 (m, 2H), 2.38 (m, 2H),
2.26 (s, 6H), 1.73 (t, J ¼ 7.5 Hz, 2H). 13C NMR (125 MHz, CD3OD)
161.3, 141.9, 130.5, 121.7, 115.0, 113.8 58.7, 55.6, 54.3, 48.1, 45.4 (ꢂ2),
27.8. HRESIMS(þ): m/z calculated [C13H23N2O1]þ 223.1805, found
223.1806.
4.7.3. 2,4,6-Tribromo-3-(((3-(dimethylamino)propyl)amino)
methyl)phenol (9)
Obtained as a yellow oil, 59% yield; 1H (500 MHz, CD3OD) dH 7.96
(s, 1H), 4.17 (s, 2H), 3.93 (s, 3H), 2.77 (m, 2H), 2.56 (m, 2H), 2.37 (s,
6H), 1.80 (t, J ¼ 7.5 Hz, 2H). 13C NMR (125 MHz, CD3OD) 155.6, 140.5,
136.9, 123.3, 121.3, 118.4, 61.1, 58.9, 54.3, 48.5, 45.3 (ꢂ2), 27.7.
HRESIMS(þ): m/z calculated for C13H20N2O1Br3 456.9120 found
456.9126.
4.7.11. N1-(4-Methoxybenzyl)-N3,N3-dimethylpropane-1,3-diamine
(22)
Obtained as a yellow solid, 28% yield; 1H (500 MHz, CD3OD) dH
7.29 (d, J ¼ 8.5 Hz, 2H), 6.92 (d, J ¼ 8.5 Hz, 2H), 3.81 (s, 3H), 3.71 (s,
2H), 2.62 (t, J ¼ 7.5 Hz, 2H), 2.38 (t, J ¼ 7.5 Hz, 2H), 2.26 (s, 6H), 1.74
(p, J ¼ 7.5 Hz, 2H). 13C NMR (125 MHz, CD3OD) 160.3, 132.7, 130.7,
114.8, 58.7, 55.7, 53.9, 48.0, 45.4 (ꢂ2), 28.0. HRESIMS(þ): m/z
calculated [C13H23N2O1]þ 223.1805, found 223.1805.
4.7.4. 2,4-Dibromo-5-(((3-(dimethylamino)propyl)amino)methyl)
phenol (12)
Obtained as a yellow solid, 47% yield; 1H (500 MHz, CD3OD) dH
7.53 (s, 1H), 6.86 (s, 1H), 3.70 (s, 2H), 2.66 (t, J ¼ 7.5 Hz, 2H), 2.44 (t,
J ¼ 7.5 Hz, 2H), 2.26 (s, 6H), 1.75 (p, J ¼ 7.5 Hz, 2H). 13C NMR
(125 MHz, CD3OD) 159.2, 138.6, 136.4, 120.5, 112.5, 110.3, 58.7, 53.6,
48.1, 45.2 (ꢂ2), 26.9. HRESIMS(þ): m/z calculated C12H19N2O1Br2
364.9858, found 364.9864.
4.7.12. N1-(2,4-Dibromo-5-methoxyphenethyl)-N3,N3-
dimethylpropane-1,3-diamine (25)
Obtained as a yellow solid, 40% yield; 1H NMR (600 MHz, CDCl3)
dH 7.65 (s, 1H), 6.78 (s, 1H), 3.84 (s, 3H), 2.86 (m, 2H), 2.84 (m, 2H),
2.67 (t, J ¼ 7.1 Hz, 2H), 2.27 (t, J ¼ 7.2 Hz, 2H), 2.17 (s, 6H), 1.65 (p,
J ¼ 7.1 Hz, 2H). 13C NMR (150 MHz, CDCl3) 155.3, 139.9, 136.2, 115.0,
113.9, 110.0, 56.4, 36.9, 49.4, 48.3, 58.0, 45.5 (ꢂ2), 28.0.
HRESIMS(þ): m/z calculated [C14H23N2O1Br2]þ 393.0171, found
393.0172.
4.7.5. N1-(2,4-Dibromo-5-methoxybenzyl)-N3,N3-
dimethylpropane-1,3-diamine (13)
Obtained as a yellow solid, 48% yield; 1H (500 MHz, CD3OD) dH
7.73 (s, 1H), 7.21 (s, 1H), 3.91 (s, 3H), 3.85 (s, 2H), 2.69 (t, J ¼ 7.5 Hz,
2H), 2.42 (t, J ¼ 7.50 Hz, 2H), 2.27 (s, 6H), 1.78 (p, J ¼ 7.5 Hz, 2H). 13
C
NMR (125 MHz, CD3OD) 157.0, 140.6, 136.9, 115.0, 114.8, 111.6, 58.7,
57.0, 53.9, 48.2, 45.5 (ꢂ2), 28.1. HRESIMS(þ): m/z calculated for
4.7.13. N1-(2,6-Dibromo-3-methoxyphenethyl)-N3,N3-
dimethylpropane-1,3-diamine (26)
C
13H21N2O1Br2 379.0015 found 379.0019.
Obtained as a yellow solid, 30% yield; 1H NMR (600 MHz, CDCl3)
dH 7.47 (d, J ¼ 8.8 Hz, 1H), 6.67 (d, J ¼ 8.8 Hz, 1H), 3.88 (s, 3H), 3.28
(tb, 2H), 2.87 (tb, 2H), 2.82 (tb, 2H), 2.40 (tb, 2H), 2.25 (s, 6H), 1.74
(tb, 2H), 13C NMR (150 MHz, CDCl3) 155.8, 139.9, 132.1, 115.9, 115.2,
111.2, 58.4, 55.6, 48.1, 48.0, 45.3 (ꢂ2), 37.8, 27.6. HRESIMS(þ): m/z
calculated [C14H23N2O1Br2]þ 393.0171, found 393.0174.
4.7.6. 2,6-Dibromo-4-(((3-(dimethylamino)propyl)amino)methyl)
phenol (17)
Obtained as a yellow solid, 66% yield; 1H (500 MHz, CD3OD) dH
7.31 (s, 2H), 3.76 (s, 2H), 2.90 (m, 2H), 2.49 (m, 2H), 2.31 (s, 6H), 1.86
(p, J ¼ 7.5 Hz, 2H). 13C NMR (125 MHz, CD3OD) 161.0, 133.5 (ꢂ2),
120.5 (ꢂ2), 115.9, 58.4, 51.8, 47.5, 45.2 (ꢂ2), 25.0. HRESIMS(þ): m/z
calculated [C12H19N2O1Br2]þ, 364.9858, found 364.9858.
4.7.14. N1-(3-Bromo-4-methoxyphenethyl)-N3,N3-
dimethylpropane-1,3-diamine (27)
4.7.7. N1-(3,5-Dibromo-4-methoxybenzyl)-N3,N3-
Obtained as a yellow solid, 60% yield; 1H NMR (600 MHz, CDCl3)
dH 7.38 (s, 1H), 7.10 (d, J ¼ 8.0 Hz, 1H), 6.82 (d, J ¼ 8.0 Hz, 1H), 3.86 (s,
3H), 2.82 (t, J ¼ 7.1 Hz, 2H), 2.71 (t, J ¼ 7.1 Hz, 2H), 2.64 (t, J ¼ 7.2 Hz,
dimethylpropane-1,3-diamine (18)
Obtained as a yellow solid, 50% yield; 1H (500 MHz, CD3OD) dH
7.63 (s, 2H), 3.90 (s, 3H), 3.74 (s, 2H), 2.63 (m t, J ¼ 7.5 Hz, 2H), 2.42
(t, J ¼ 7.5 Hz, 2H, m), 2.30 (s, 6H), 1.75 (p, J ¼ 7.5 Hz, 2H). 13C NMR
2H), 2.27 (t, J ¼ 7.2 Hz, 2H), 2.18 (s, 6H), 1.63 (p, J ¼ 7.2 Hz, 2H). 13
C
NMR (151 MHz, CDCl3) 154.4, 134.0, 133.5, 128.8, 112.1, 111.7, 58.2,

N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
549
56.4, 51.2, 48.4, 45.6 (ꢂ2), 35.2, 28.1. HRESIMS(þ): m/z calculated
(150 MHz, CDCl3) 155.5, 139.3, 136.4, 114.9, 114.0, 110.0, 81.6, 71.7,
56.5, 38.2, 48.1, 36.5. HRESIMS(þ): m/z calculated [C12H14N1O1Br2]þ
345.9436, found 345.9423.
[C14H24N2O1Br]þ 315.1066, found 315.1063.
4.7.15. N1-(5-Bromo-2-methoxyphenethyl)-N3,N3-
dimethylpropane-1,3-diamine (28)
4.7.22. N-(2,4-Dibromo-5-methoxyphenethyl)but-3-yn-1-amine
(35)
Obtained as a yellow solid, 65% yield; 1H NMR (600 MHz, CDCl3)
dH 7.28 (s, 1H), 7.25 (dd, J ¼ 8.5, 1.2 Hz, 1H), 6.70 (dd, J ¼ 8.5, 1.2 Hz,
1H), 2.81 (d, J ¼ 6.6 Hz, 2H), 2.77 (d, J ¼ 6.6 Hz, 2H), 2.65 (t,
Obtained as a yellow solid, 50% yield; 1H NMR (600 MHz, CDCl3)
dH 7.68 (s, 1H), 6.80 (s, 1H), 3.87 (s, 3H), 2.89 (broad, 4H), 2.82 (t,
J ¼ 7.1 Hz, 2H), 2.28 (t, J ¼ 7.1 Hz, 2H), 2.19 (s, 6H), 1.64 (m, 2H). 13
C
J ¼ 7.0 Hz, 2H), 2.40 (d, J ¼ 7.0, 2.5 Hz, 2H), 1.97 (t, J ¼ 2.5 Hz, 2H). 13
C
NMR (150 MHz, CDCl3) 156.9, 133.0, 131.1, 130.1, 112.7, 112.2, 58.2,
55.7, 49.6, 48.3, 45.7 (ꢂ2), 30.8, 28.2. HRESIMS(þ): m/z calculated
[C14H24N2O1Br]þ 315.1066, found 315.1068.
NMR (150 MHz, CDCl3) 155.2, 139.7, 136.4, 115.0, 113.8, 109.2, 82.3,
69.5, 56.4, 48.5, 47.7, 36.8, 19.4. HRESIMS(þ): m/z calculated
[C13H16N1O1Br2]þ 359.9593, found 359.9593.
4.7.16. N1-(3-Methoxyphenethyl)-N3,N3-dimethylpropane-1,3-
diamine (29)
4.7.23. 1-(2,4-Dibromo-5-methoxyphenethyl)pyrrolidine (36)
Obtained as a yellow solid, 40% yield; 1H NMR (600 MHz, CDCl3)
dH 7.67 (s, 1H), 6.91 (s, 1H), 3.88 (s, 3H), 2.96 (m, 2H), 2.75 (m, 2H),
2.70 (m, 4H), 1.95 (t, broad, 4H). 13C NMR (150 MHz, CDCl3) 155.7,
139.9, 136.4, 114.9, 114.2, 110.2, 56.7, 56.1, 53.7 (ꢂ2), 35.5, 23.6 (ꢂ2).
HRESIMS(þ): m/z calculated [C13H18N1O1Br2]þ 361.9749, found
361.9742.
Obtained as a yellow solid, 57% yield; 1H (500 MHz, CD3OD) dH
d
7.26 (t, J ¼ 8.0 Hz, 1H), 6.94 (m, 3H), 3.84 (s, 3H), 2.90 (m, 2H), 2.84
(m, 2H), 2.71 (t, J ¼ 7.5 Hz, 2H), 2.39 (t, J ¼ 7.5 Hz, 2H), 2.26 (s, 6H),
1.74 (p, J ¼ 7.5 Hz, 2H). 13C NMR (125 MHz, CD3OD) 160.3, 140.6,
129.3, 120.6, 114.1, 111.4, 57.4, 54.2, 50.1, 47.4, 43.8 (ꢂ2), 34.7, 25.5.
HRESIMS(þ): m/z calculated [C14H25N2O1]þ, 237.1961, found
237.1965.
4.7.24. N1,N1-Dimethyl-N3-(2-(naphthalen-2-yl)ethyl)propane-1,3-
diamine (37)
4.7.17. N1-(2,4-Dibromo-5-methoxyphenethyl)-N3,N3-dimethyl-N1-
(prop-2-yn-1-yl)propane-1,3-diamine (30)
Obtained as a white solid, 70% yield; 1H NMR (600 MHz, CDCl3)
dH 7.79 (d, J ¼ 8.1 Hz, 1H), 7.78 (d, J ¼ 8.1 Hz, 2H), 7.65 (s, 1H), 7.45e
7.41 (m, 2H) 7.35 (d, J ¼ 8.1 Hz, 1H), 2.96 (m, 4H), 2.67 (t, J ¼ 7.4 Hz,
Obtained as a yellow solid, 35% yield; 1H NMR (600 MHz, CDCl3)
dH 7.67 (s, 1H), 6.80 (s, 1H), 3.87 (s, 3H), 3.42 (s, 2H), 2.85 (t,
J ¼ 7.4 Hz, 2H), 2.74 (t, J ¼ 7.4 Hz, 2H), 2.59 (t, J ¼ 7.3 Hz, 2H), 2.27 (t,
J ¼ 7.4 Hz, 2H), 2.21 (s, 6H), 1.63 (m, 2H). 13C NMR (150 MHz, CDCl3)
155.3, 140.0, 136.4, 115.0, 113.9, 109.8, 57.7, 56.4, 53.3, 51.6, 45.5
(ꢂ2), 42.1, 34.5, 25.7. HRESIMS(þ): m/z calculated [C17H25N2O1Br2]þ
431.0328, found 431.0316.
2H), 2.26 (t, J ¼ 7.4 Hz, 2H), 2.15 (s, 6H), 1.63 (p, J ¼ 7.4 Hz, 2H). 13
C
NMR (150 MHz, CDCl3) 137.7, 133.6, 133.1, 127.5 (ꢂ2), 127.1, 126.8
(ꢂ2), 125.7,125.0, 57.8, 50.6, 47.9, 45.2 (ꢂ2), 36.2, 27.7. HRESIMS(þ):
m/z calculated [C17H25N2]þ 257.2012, found 257.2005.
4.7.25. N1,N1-Dimethyl-N3-(2-(pyridin-3-yl)ethyl)propane-1,3-
diamine (38)
4.7.18. N-(2,4-Dibromo-5-methoxyphenethyl)-N-(3-
(dimethylamino)propyl)acetamide (31)
Obtained as a pale yellow solid, 75% yield; 1H NMR (600 MHz,
CDCl3) dH 8.51 (d, J ¼ 4.5 Hz, 1H), 7.57 (td, J ¼ 7.7, 1.9 Hz, 1H), 7.15 (d,
J ¼ 7.7 Hz, 1H), 7.09 (dd, J ¼ 4.5, 7.7 Hz, 1H), 2.97 (m, 4H), 2.65 (t,
J ¼ 7.3 Hz, 2H), 2.26 (t, J ¼ 7.3 Hz, 2H), 2.17 (s, 6H), 1.62 (p, J ¼ 7.3 Hz,
2H). 13C NMR (150 MHz, CDCl3) 160.5,149.4,136.4,123.4,121.3, 58.1,
49.5, 48.3, 45.6 (ꢂ2), 38.6, 28.1. HRESIMS(þ): m/z calculated
[C12H22N3]þ 208.1808, found 208.1811.
Obtained as a yellow solid, 35% yield; 1H NMR (600 MHz, CDCl3)
dH 7.69 (s, 1H), 6.97 (s, 1H), 3.93 (s, 3H), 3.55 (m, 4H), 3.00 (m, 4H),
2.79 (s, 6H), 2.16 (q, J ¼ 7.5, 2H), 2.08 (s, 3H). 13C NMR (150 MHz,
CDCl3) 171.6, 156.0, 137.4, 136.4, 114.9, 114.5, 111.4, 57.1, 56.4, 48.8,
43.6 (ꢂ2), 43.3, 35.8, 24.0, 21.7. HRESIMS(þ): m/z calculated
[C16H25N2O2Br2]þ 435.0277, found 435.0276.
4.7.26. N1,N1-Dimethyl-N3-(2-(thiophen-2-yl)ethyl)propane-1,3-
diamine (39)
4.7.19. N1-(2,4-Dibromo-5-methoxyphenethyl)propane-1,3-
diamine (32)
Obtained as a yellow solid, 70% yield; 1H NMR (600 MHz, CDCl3)
dH 7.13 (d, J ¼ 5.1 Hz, 1H), 6.92 (dd, J ¼ 5.1, 3.5 Hz, 1H), 6.82
(J ¼ 3.5 Hz, 1H), 3.02 (t, J ¼ 6.9 Hz, 2H), 2.90 (t, J ¼ 6.9 Hz, 2H), 2.67
(t, J ¼ 7.1 Hz, 2H), 2.28 (t, J ¼ 7.2 Hz, 2H), 2.19 (s, 6H), 1.64 (p,
J ¼ 7.2 Hz, 2H). 13C NMR (150 MHz, CDCl3) 142.8, 126.9, 125.1, 123.6,
58.1, 51.3, 48.3, 45.6 (ꢂ2), 30.5, 28.1. HRESIMS(þ): m/z calculated
[C11H21N2S]þ 213.1419, found 213.1412.
Obtained as a yellow solid, 60% yield; 1H NMR (600 MHz, DMSO-
d6) dH 7.81 (s, 1H), 7.27 (s, 1H), 3.88 (s, 3H), 3.12 (m, 4H), 3.05 (t,
J ¼ 7.4 Hz, 2H), 2.93 (t, J ¼ 7.4 Hz, 2H), 2.02 (m, 2H). 13C NMR
(150 MHz, DMSO-d6) 155.0, 137.4, 135.0, 114.9, 114.5, 110.1, 56.4,
45.6, 31.5, 43.7, 35.9, 23.4. HRESIMS(þ): m/z calculated
[C12H19N2O1Br2]þ 364.9858, found 364.9859.
4.7.20. 3-((2,4-Dibromo-5-methoxyphenethyl)amino)propan-1-ol
(33)
4.7.27. N1-((2,3-Dihydro-1H-inden-2-yl)methyl)-N3,N3-
dimethylpropane-1,3-diamine (40)
Obtained as a yellow solid, 70% yield; 1H NMR (600 MHz, DMSO-
d6) dH 7.82 (s, 1H), 7.18 (s, 1H), 3.88 (s, 3H), 3.50 (t, J ¼ 5.9 Hz, 2H),
3.17 (m, 4H), 3.05 (m, 2H), 3.04 (m, 2H), 1.78 (m, 2H). 13C NMR
(151 MHz, DMSO-d6) 155.1, 136.6, 135.3, 114.8, 114.4, 109.9, 56.5,
57.8, 45.8, 31.6, 44.8, 28.5. HRESIMS(þ): m/z calculated
[C12H18N1O2Br2]þ 365.9698, found 365.9691.
Obtained as a yellow solid, 70% yield; 1H NMR (600 MHz, CDCl3)
dH 7.20 (m, 4H), 3.81 (tt, J ¼ 6.8, 4.4 Hz,1H), 3.31 (dd, J ¼ 16.4, 6.7 Hz,
2H), 3.19 (dd, J ¼ 16.3, 4.4 Hz, 2H), 3.12 (t, J ¼ 6.0 Hz, 2H), 2.59 (t,
J ¼ 6.0 Hz, 2H), 2.15 (s, 6H), 1.98 (p, J ¼ 6.0 Hz, 2H). 13C NMR
(150 MHz, CDCl3) 139.3(ꢂ2), 127.5 (ꢂ2), 125.1 (ꢂ2), 59.5, 58.5, 47.5,
44.7 (ꢂ2), 37.5 (ꢂ2), 22.7. HRESIMS(þ): m/z calculated [C14H23N2]þ
219.1856, found 219.1848.
4.7.21. N-(2,4-Dibromo-5-methoxyphenethyl)prop-2-yn-1-amine
(34)
4.7.28. N1-(2-Bromophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (41)
Obtained as a yellow solid, 55% yield; 1H NMR (600 MHz, CDCl3)
dH 7.69 (s, 1H), 6.82 (s, 1H), 3.88 (s, 3H), 3.48 (d, J ¼ 2.4 Hz, 2H), 2.99
(t, J ¼ 7.3 Hz, 2H), 2.91 (t, J ¼ 7.3 Hz, 2H), 2.23 (s, 1H). 13C NMR
Obtained as yellow oil, 70% yield; 1H NMR (600 MHz, CDCl3) dH
7.52 (d, J ¼ 6 Hz, 1H), 7.25e7.20 (m, 2H), 7.06 (m, 1H), 2.93 (t,

550
N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
J ¼ 7.2 Hz, 2H), 2.87 (t, J ¼ 7.2 Hz, 2H), 2.69 (t, J ¼ 7.3 Hz, 2H), 2.29 (t,
J ¼ 7.3 Hz, 2H), 2.19 (s, 6H), 1.65 (ddd, J ¼ 7.3 Hz, 2H). 13C NMR
(150 MHz, CDCl3) 139.7, 133.0, 130.9, 127.9, 127.5, 124.7, 58.2, 49.6,
48.3, 45.7 (ꢂ2), 36.9, 28.2. HRESIMS(þ): m/z calculated
[C13H22N2O1Br]þ 285.0960, found 285.0958.
HRESIMS(þ): m/z calculated [C13H22Cl1N2]þ 241.1466, found
241.1465.
4.7.35. N1-(3-Chlorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (48)
Obtained as white oil, 75% yield; 1H NMR (600 MHz, CDCl3) dH
7.28 (t, J ¼ 7.7 Hz, 1H), 7.26 (s, 1H), 7.24 (d, J ¼ 7.7 Hz, 1H), 7.16 (d,
J ¼ 7.7 Hz, 1H), 2.95 (t, J ¼ 6.9 Hz, 2H), 2.88 (t, J ¼ 6.9 Hz, 2H), 2.77 (t,
J ¼ 7.0 Hz, 2H), 2.35 (t, J ¼ 7.0 Hz, 2H), 2.20 (s, 6H), 1.72 (p, J ¼ 7.0 Hz,
2H). 13C NMR (150 MHz, CDCl3) 141.9, 134.4, 129.9, 129.0, 127.2,
126.6, 58.4, 50.8, 48.8, 45.5 (ꢂ2), 35.6, 27.1. HRESIMS(þ): m/z
calculated [C13H22Cl1N2]þ 241.1466, found 241.1461.
4.7.29. N1-(3-Bromophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (42)
Obtained as yellow oil, 70% yield; 1H NMR (600 MHz, CDCl3) dH
7.35 (s, 1H), 7.33 (d, J ¼ 7.8 Hz, 1H), 7.16e7.11 (m, 2H), 2.85 (t,
J ¼ 7.1 Hz, 2H), 2.76 (t, J ¼ 7.1 Hz, 2H), 2.65 (t, J ¼ 7.0 Hz, 2H), 2.27 (t,
J ¼ 7.2 Hz, 2H), 2.18 (s, 6H), 1.62 (p, J ¼ 7.1 Hz, 2H). 13C NMR
(150 MHz, CDCl3) 142.7, 131.9, 130.1, 129.4, 127.5, 122.6, 58.2, 51.0,
48.4, 45.6 (ꢂ2), 36.2, 28.1. HRESIMS(þ): m/z calculated
[C13H22N2O1Br]þ 285.0960, found 285.0961.
4.7.36. N1-(4-Chlorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (49)
Obtained as white oil, 75% yield; 1H NMR (600 MHz, CDCl3) dH
7.24 (d, J ¼ 8.3 Hz, 2H), 7.13 (d, J ¼ 8.3 Hz, 2H), 2.83 (t, J ¼ 7.1 Hz, 2H),
2.76 (t, J ¼ 7.1 Hz, 2H), 2.63 (t, J ¼ 7.2 Hz, 2H), 2.26 (t, J ¼ 7.2 Hz, 2H),
1.62 (p, J ¼ 7.2 Hz, 2H). 13C NMR (150 MHz, CDCl3) 138.8,132.0,130.2
(ꢂ2), 128.6 (ꢂ2), 58.2, 51.1, 48.4, 45.6 (ꢂ2), 35.9, 28.1. HRESIMS(þ):
m/z calculated [C13H22Cl1N2]þ 241.1466, found 241.1463.
4.7.30. N1-(4-Bromophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (43)
Obtained as yellow oil, 60% yield; 1H NMR (600 MHz, CDCl3) dH
7.40 (d, J ¼ 8.1 Hz, 2H), 7.07 (d, J ¼ 8.0 Hz, 2H), 2.83 (t, J ¼ 7.2 Hz, 2H),
2.74 (t, J ¼ 7.1 Hz, 2H), 2.64 (t, J ¼ 7.1 Hz, 2H), 2.26 (t, J ¼ 7.2 Hz, 2H),
2.17 (s, 6H), 1.63 (p, J ¼ 7.2 Hz, 2H). 13C NMR (150 MHz, CDCl3) 139.3,
131.6 (ꢂ2), 130.6 (ꢂ2), 120.0, 77.4, 76.9, 76.7, 58.1, 51.1, 48.4, 45.6
(ꢂ2), 35.9, 28.1. HRESIMS(þ): m/z calculated [C13H22N2O1Br]þ
285.0960, found 285.0959.
4.7.37. N1-(3-Chloro-4-methoxyphenethyl)-N3,N3-
dimethylpropane-1,3-diamine (50)
Obtained as pale yellow oil, 68% yield; 1H NMR (600 MHz,
CDCl3) dH 7.22 (s, 1H), 7.07 (d, J ¼ 8.3 Hz, 1H), 6.86 (d, J ¼ 8.3 Hz, 1H),
3.88 (s, 3H), 2.85 (t, J ¼ 7.0 Hz, 2H), 2.75 (t, J ¼ 7.0 Hz, 2H), 2.69 (t,
J ¼ 7.1 Hz, 2H), 2.29 (t, J ¼ 7.1 Hz, 2H), 2.17 (s, 6H), 1.66 (p, J ¼ 7.1 Hz,
2H). 13C NMR (150 MHz, CDCl3) 153.6, 133.1, 130.5, 128.1, 122.5,
112.4, 58.4, 56.4, 51.1, 48.7, 45.6 (ꢂ2), 35.0, 27.7. HRESIMS(þ): m/z
calculated [C14H24N2O1Cl]þ 271.1571, found 271.1563.
4.7.31. N1-(2-Fluorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (44)
Obtained as pale yellow oil, 70% yield; 1H NMR (600 MHz, CDCl3)
dH 7.23e7.15 (m, 2H), 7.05 (t, J ¼ 7.5 Hz, 1H), 7.00 (t, J ¼ 7.5 Hz, 1H),
2.85 (dq, J ¼ 11.1, 5.6 Hz, 4H), 2.66 (t, J ¼ 7.1 Hz, 2H), 2.28 (t,
J ¼ 7.1 Hz, 2H), 2.18 (s, 6H), 1.64 (p, J ¼ 7.1 Hz, 2H). 13C NMR
(150 MHz, CDCl3) 162.2, 131.1, 128.0, 127.2, 124.1, 115.5, 58.1, 50.0,
48.3, 45.6 (ꢂ2), 29.9, 28.1. HRESIMS(þ): m/z calculated
[C13H22F1N2]þ 225.1761, found 225.1752.
4.7.38. N1-(3,4-Dichlorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (51)
Obtained as pale yellow oil, 70% yield; 1H NMR (600 MHz, CDCl3)
dH 7.34 (d, J ¼ 8.2 Hz, 1H), 7.30 (d, J ¼ 2.0 Hz, 1H), 7.03 (dd, J ¼ 8.2,
2.0 Hz, 1H), 2.83 (t, J ¼ 7.1 Hz, 2H), 2.74 (t, J ¼ 7.1 Hz, 2H), 2.64 (t,
J ¼ 7.1 Hz, 2H), 2.27 (t, J ¼ 7.2 Hz, 2H), 2.17 (s, 6H), 1.62 (p, J ¼ 7.1 Hz,
2H). 13C NMR (150 MHz, CDCl3) 140.7, 132.4, 130.8, 130.4, 130.2,
128.3, 58.2, 50.8, 48.4, 45.7 (ꢂ2), 35.7, 28.1. HRESIMS(þ): m/z
calculated [C13H21Cl2N2]þ 275.1076, found 275.1073.
4.7.32. N1-(3-Fluorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (45)
Obtained as pale yellow oil, 75% yield; 1H NMR (600 MHz, CDCl3)
dH 7.23 (m, 1H), 6.97 (d, J ¼ 7.5 Hz, 1H), 6.89 (m, 1H), 6.85 (m, 1H),
2.85 (t, J ¼ 7.1 Hz, 2H), 2.78 (t, J ¼ 7.1 Hz, 2H), 2.64 (t, J ¼ 7.1 Hz, 2H),
2.26 (t, J ¼ 7.1 Hz, 2H), 2.17 (s, 6H), 1.63 (m, 2H). 13C NMR (150 MHz,
CDCl3) 163.9, 142.9, 130.0, 124.5, 115.7, 113.2, 58.1, 51.0, 48.4, 45.6
(ꢂ2), 36.2, 28.0. HRESIMS(þ): m/z calculated [C13H22F1N2]þ
225.1761, found 225.1752.
4.7.39. N1-(2,4-Dichlorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (52)
Obtained as white oil, 80% yield; 1H NMR (600 MHz, CDCl3) dH
7.37 (d, J ¼ 2.1 Hz, 1H), 7.25 (d, J ¼ 8.2 Hz, 1H), 7.19 (dd, J ¼ 8.2,
2.1 Hz, 1H), 2.97 (t, J ¼ 7.5 Hz, 2H), 2.91 (d, J ¼ 7.5 Hz, 2H), 2.76 (t,
J ¼ 6.8 Hz, 2H), 2.33 (t, J ¼ 6.8 Hz, 2H), 2.17 (s, 6H), 1.70 (p, J ¼ 6.8 Hz,
2H). 13C NMR (150 MHz, CDCl3) 134.9 (ꢂ2), 133.0, 132.1, 129.5, 127.3,
58.5, 48.9, 48.8, 45.5 (ꢂ2), 33.2, 27.0. HRESIMS(þ): m/z calculated
[C13H21Cl2N2]þ 275.1076, found 275.1079.
4.7.33. N1-(4-Fluorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (46)
Obtained as yellow oil, 70% yield; 1H NMR (600 MHz, CDCl3) dH
7.15 (dd, J ¼ 8.4, 5.6 Hz, 2H), 6.96 (t, J ¼ 8.7 Hz, 2H), 2.83 (t,
J ¼ 7.4 Hz, 2H), 2.76 (t, J ¼ 7.1 Hz, 2H), 2.64 (t, J ¼ 7.1 Hz, 2H), 2.26 (t,
J ¼ 7.2 Hz, 2H), 2.17 (s, 6H), 1.62 (p, J ¼ 7.1 Hz, 2H). 13C NMR
(150 MHz, CDCl3) 160.8, 135.9, 130.2 (ꢂ2), 115.4 (ꢂ2), 58.1, 51.4,
48.4, 45.6 (ꢂ2), 35.7, 28.1. HRESIMS(þ): m/z calculated
[C13H22F1N2]þ 225.1761, found 225.1755.
4.7.40. N1-(2,6-Dichlorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (53)
Obtained as white oil, 75% yield; 1H NMR (600 MHz, CDCl3) dH
7.27 (d, J ¼ 7.6 Hz, 2H), 7.06 (t, J ¼ 7.6 Hz, 1H), 3.12 (m, 2H), 2.83 (m,
2H), 2.71 (t, J ¼ 7.3 Hz, 2H), 2.31 (t, J ¼ 7.3 Hz, 2H), 2.21 (s, 6H), 1.67
(p, J ¼ 7.3 Hz, 2H). 13C NMR (150 MHz, CDCl3) 136.3, 135.7, 128.3
(ꢂ2), 127.9 (ꢂ2), 58.2, 48.1, 47.9, 45.7 (ꢂ2), 32.2, 28.2. HRESIMS(þ):
m/z calculated [C13H21Cl2N2]þ 275.1076, found 275.1077.
4.7.34. N1-(2-Chlorophenethyl)-N3,N3-dimethylpropane-1,3-
diamine (47)
Obtained as white oil, 75% yield; 1H NMR (600 MHz, CDCl3) dH
7.34 (dd, J ¼ 7.6, 1.5 Hz, 1H), 7.24 (dd, J ¼ 7.6, 1.5 Hz, 1H), 7.18 (td,
J ¼ 7.6, 1.5 Hz,1H), 7.14 (td, J ¼ 7.6,1.5 Hz,1H), 2.93 (t, J ¼ 7.2 Hz, 2H),
2.87 (t, J ¼ 7.2 Hz, 2H), 2.68 (t, J ¼ 7.1 Hz, 2H), 2.29 (t, J ¼ 7.1 Hz, 2H),
2.19 (s, 6H), 1.65 (p, J ¼ 7.1 Hz, 2H). 13C NMR (151 MHz, CDCl3) 137.9,
134.3,130.9,129.7,127.7,126.9, 58.2, 49.5, 48.3, 45.7 (ꢂ2), 34.3, 28.2.
4.7.41. N1-(2-Chloro-6-fluorophenethyl)-N3,N3-dimethylpropane-
1,3-diamine (54)
Obtained as yellow oil, 70% yield; 1H NMR (600 MHz, CDCl3) dH
7.15 (d, J ¼ 8.1 Hz, 1H), 7.11 (td, J ¼ 8.1, 5.9 Hz, 1H), 6.95 (td, J ¼ 8.1,

N.B. Pham et al. / European Journal of Medicinal Chemistry 74 (2014) 541e551
551
1.3 Hz, 1H), 2.98 (t, J ¼ 7.5 Hz, 2H), 2.84 (t, J ¼ 7.5 Hz, 2H), 2.69 (t,
Appendix A. Supplementary material
J ¼ 7.1 Hz, 2H), 2.30 (t, J ¼ 7.1 Hz, 2H), 2.20 (s, 6H), 1.66 (p, J ¼ 7.1 Hz,
2H). 13C NMR (150 MHz, CDCl3) 162.2, 135.3, 127.9, 126.2, 125.33,
114.1, 58.2, 48.6, 48.1, 45.7 (ꢂ2), 28.2, 27.4. HRESIMS(þ): m/z
calculated [C13H21N2Cl1F1]þ 259.1371, found 259.1375.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2013.12.050.
References
4.7.42. N1,N1-Dimethyl-N3-(3-(trifluoromethyl)phenethyl)propane-
1,3-diamine (55)
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Obtained as yellow oil, 55% yield; 1H NMR (600 MHz, CDCl3) dH
7.46 (m, 2H), 7.43e7.38 (m, 2H), 2.87 (m, 4H), 2.66 (t, J ¼ 7.1 Hz, 2H),
2.27 (t, J ¼ 7.1 Hz, 2H), 2.17 (s, 6H), 1.63 (m, 2H). 13C NMR (150 MHz,
CDCl3) 143.2, 141.3, 132.3, 128.9 (ꢂ2), 125.5, 123.1, 58.2, 51.2, 48.4,
45.6 (ꢂ2), 36.4, 28.1. HRESIMS(þ): m/z calculated [C14H22N2F3]þ
275.1729, found 275.1731.
[5] A.K. Ghose, T. Herbertz, R.L. Hudkins, B.D. Dorsey, J.P. Mallamo, ACS Chem.
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(2002) 2261e2266.
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We gratefully acknowledge Queensland Smart State Innova-
tion Project Fund e National and International Research Alliances
and Partnerships Program and NIH grants AI75641 and
AI78962. We also thank Dr. H. T. Vu for acquiring the HRESIMS
measurement.