N-[4-(Methylsulfonylamino)benzyl]thiourea analogues as vanilloid receptor antagonists: Analysis of structure-activity relationships for the 'C-Region'

Article abstract of DOI:10.1016/j.bmc.2003.10.047

We recently reported that N-(4-t-butylbenzyl)-N′-[4- (methylsulfonylamino)benzyl] thiourea (2) was a high affinity antagonist of the vanilloid receptor with a binding affinity of K_i=63 nM and an antagonism of K_i=53.9 nM in rat VR1 heterologously expressed in Chinese hamster ovary (CHO) cells (Mol. Pharmacol. 2002, 62, 947-956). In an effort to further improve binding affinity and antagonistic potency, we have modified the C-region of the lead 4-t-butylbenzyl group with diverse surrogates, such as araalkyl, alkyl, 4-alkynylbenzyl, indanyl, 3,3-diarylpropyl, 4-alkoxybenzyl, 4-substituted piperazine and piperidine. The lipophilic surrogates, arylalkyl and alkyl, conferred modest decreases in binding affinities and antagonistic potencies; the groups having heteroatoms resulted in dramatic decreases. Our findings indicate that 4-t-butylbenzyl is one of the most favorable groups for high receptor binding and potent antagonism to VR1 in this structural series.

Full text of DOI:10.1016/j.bmc.2003.10.047

Bioorganic & Medicinal Chemistry 12 (2004) 371–385
N-[4-(Methylsulfonylamino)benzyl]thiourea analogues as vanilloid
receptor antagonists: analysis of structure–activity relationships
for the ‘C-Region’
Jeewoo Lee,a,* Sang-Uk Kang,a Ju-Ok Lim,a Hyun-Kyung Choi,a Mi-kyung Jin,a
b
Attila Toth,b Larry V.Pearce, Richard Tran,b Yun Wang,b Tamas Szabob
b
and Peter M.Blumberg
aResearch Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Shinlim-Dong, Kwanak-Ku,
Seoul 151-742, South Korea
bLaboratory of Cellular Carcinogenesis and Tumor Promotion, Center for Cancer Research, National Cancer Institute, NIH,
Bethesda, MD 20892, USA
Received 9 October 2003; revised 9 October 2003; accepted 27 October 2003
Abstract—We recently reported that N-(4-t-butylbenzyl)-N0-[4-(methylsulfonylamino)benzyl] thiourea (2) was a high affinity
antagonist of the vanilloid receptor with a binding affinity of Ki=63 nM and an antagonism of Ki=53.9 nM in rat VR1 hetero-
logously expressed in Chinese hamster ovary (CHO) cells (Mol. Pharmacol. 2002, 62, 947–956).In an effort to further improve
binding affinity and antagonistic potency, we have modified the C-region of the lead 4-t-butylbenzyl group with diverse surrogates,
such as araalkyl, alkyl, 4-alkynylbenzyl, indanyl, 3,3-diarylpropyl, 4-alkoxybenzyl, 4-substituted piperazine and piperidine.The
lipophilic surrogates, arylalkyl and alkyl, conferred modest decreases in binding affinities and antagonistic potencies; the groups
having heteroatoms resulted in dramatic decreases.Our findings indicate that 4-t-butylbenzyl is one of the most favorable groups for
high receptor binding and potent antagonism to VR1 in this structural series.
# 2003 Elsevier Ltd.All rights reserved.
1. Introduction
activators by VR1 antagonists has been considered as a
promising strategy to inhibit the transmission of painful
The vanilloid receptor VR11 is a ligand-gated non-
selective cation channel present on polymodal nocicep-
tors, which is activated by protons,2 heat,3 natural
ligands such as capsaicin (CAP),4 resiniferatoxin
(RTX),5 and endogenous substances such as ananda-
mide6 and the lipoxygenase product 12-HPETE.7 VR1
has been cloned from dorsal root ganglia (DRG) of the
rat8 and from the human,9 and is structurally a member
of the transient receptor potential (TRP) family of chan-
nel proteins,10 oligomerizing as a tetramer.11 The vanilloid
receptor is expressed predominantly on unmyelinated
pain-sensing nerve fibers (C-fibers) and small Ad, fibers in
the dorsal root, trigeminal, and nodose ganglia.Since
the activation of the vanilloid receptor triggers cation
influx resulting in excitation of primary sensory neu-
rons, action potentials, and ultimately the central
perception of pain, the blocking of pain-producing
signals from the periphery to the CNS.Proof of princi-
ple for this approach has been provided with VR1
antagonists such as capsazepine, iodo-RTX, urea com-
pounds and N-[4-(methylsulfonylamino)benzyl]thiourea
compounds.
Capsazepine, the first competitive antagonist,12 has only
modest potency and is somewhat non-specific, also
antagonizing voltage sensitive calcium channels13 and
the nicotinic cholinergic receptor14 in rat.In vitro, cap-
sazepine has been shown not only to inhibit capsaicin-
mediated responses in rat,15,16 mouse17 and guinea
pig,18 but also low pH mediated activation of human or
guinea pig but not rat VR1.19,20 5-Iodo-RTX, prepared
semi-synthetically from RTX by iodination, was repor-
ted to display potent antagonism in rat and human
VR1.21,22 More recently, several series of synthetic urea
compounds have been described as VR1 antago-
nists23À26 and, in particular, BCTC was characterized in
vitro and in vivo as a potent, orally-effective, VR1
selective antagonist.25,26 Potential therapeutic applica-
Keywords: Vanilloid Receptor 1; Antagonist.
* Corresponding author.Tel:. +82-2-880-7846; fax: +82-2-888-0649;
e-mail: jeewoo@snu.ac.kr
0968-0896/$ - see front matter # 2003 Elsevier Ltd.All rights reserved.
doi:10.1016/j.bmc.2003.10.047

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J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
tions of these antagonists include chronic pain, such as
that associated with diabetic neuropathy, post-herpetic
neuralgia, arthritis and cluster headache, urologic pro-
blems including detrusor hyperreflexia and bladder
hypersensitivity, and pruritus.1
the N-[4-(methylsulfonylamino)benzyl]thiourea group,
corresponding to the crucial antagonistic pharmaco-
phore, was fixed as the A- and B-regions and the C-
region was substituted with other appropriate hydro-
phobic groups utilized for analysis of capsaicinoid SAR.
In this paper, we describe the synthesis, in vitro char-
acterization using CHO cells heterologously expressing
rat VR1, and structure relationship analysis of a series of
N-4-(methylsulfonylamino)benzyl thiourea analogues.
Vanilloid receptor ligands such as capsaicin have been
divided into three structural regions, the A-, B- and C-
regions,4 as shown in Figure 1.Recently, we discovered
that isosteric replacement of the phenolic OH group in
the A-region of potent agonists by an alkylsulfonyl-
amido group was able to maintain their strong affinities
while modifying their activities from agonism to antag-
onism.27À29 The acid dissociation constant of the NH
group in alkylsulfonamides is close to that of the phe-
nolic OH group.Its effectiveness as a bioisostere in this
setting implies that the NH portion of the alkylsulfon-
amide hydrogen bonds with the receptor site by aligning
itself in a manner closely approximating the phenolic
OH group with respect to both bond distances and
bond angles.Structure activity analysis of alkylsulfon-
amides indicated that the methylsulfonamido group was
optimal for maximal binding and antagonism.29 Conse-
quently, the isosteric replacement of the phenolic OH
group in the potent agonists N-(4-t-butylbenzyl)-N0-(4-
hydroxy-3-methoxybenzyl)thioureas (1, Ki=58.6 nM,
agonism EC50=2.55 nM)30 and N-(3-acyloxy-2-benzyl-
propyl)-N0-(4-hydroxy-3-methoxybenzyl)thioureas (3,
Ki=17.4 nM, agonism EC50=1.97 nM)31 with the
methylsulfonamido group led to the corresponding
potent antagonists, 2 (Ki=63 nM, antagonism Ki=53.9
nM)27 and 4 (Ki=29.3 nM, antagonism Ki=67 nM),29
with high binding affinities, respectively (Fig.1 ).
2. Chemistry
The syntheses of N-[4-(methylsulfonylamino)benzyl]
thiourea analogues were achieved by the general cou-
pling methods between 4-(methylsulfonylamino)benzyl
isothiocyanate (5)29 and the corresponding amines.As
shown in Scheme 1, arylalkyl amines, such as 3,4-dime-
thylphenylmethyl, ethyl, and propyl amines, 4-t-butyl-
phenylmethyl, ethyl amines and 4-trifluoromethylbenzyl,
and oleyl amine were coupled with isothiocyanate (5) to
afford the corresponding thioureas 2, 6–11, respectively.
The syntheses of N-(4-alkynylbenzyl) thiourea analo-
gues were outlined in Scheme 2.4-Iodobenzyl bromide
(12) was converted into N-Boc 4-iodobenzyl amine (14)
in 3 steps.Palladium-catalyzed coupling of 14 with sev-
eral alkynes followed by N-Boc deprotection under
acidic conditions provided 4-alkynylbenzyl amines (20–
24), which underwent the general coupling to provide
thioureas 25–29.The synthesis of the N-(1-methylindan-
5-yl)methyl thiourea analogue was shown in Scheme 3.
5-Bromo indanone (30) was converted into the corres-
ponding cyanide (31) with copper cyanide.The ketone
of 31 was methylated and subsequently eliminated to
provide 3-methylindene (32).Nitrile reduction of 32
followed by the general coupling afforded thiourea 34.
The syntheses of N-(3-phenyl-3-arylpropyl) thiourea
analogues was represented in Scheme 4.The coupling of
cinnamamide (35) with several iodobenzenes by the
Heck reaction32 produced 3-phenyl-3-aryl-2-propen-
amides (36–38, respectively).The 2-propenamides were
reduced to the corresponding propyl amines (43–45),
which, along with commercially available 3,3-diphenyl-
propyl amine (42), underwent the general coupling to
afford thioureas 46–47, respectively.The syntheses of N-
(4-alkoxybenzyl) thiourea analogues were outlined in
Scheme 5.4-Cyanophenol ( 50) was alkylated with sev-
eral halides to produce 4-alkoxybenzonitriles (51–53,
respectively).Nitrile reduction of 51–53 followed by the
general coupling produced thioureas 57–59, respec-
tively. N-piperazinyl thiourea analogues (61, 63, 65)
were prepared starting from 4-phenyl (60), 4-benzyl
(62), and 4-benzhydryl (65) piperazines, respectively, by
following the general coupling method as shown in
Scheme 6.The syntheses of N-piperidinyl thiourea ana-
logues was shown in Schemes 7 and 8.The reaction of
N-Boc ethyl isonipecotate (69) with phenyl Grignard
and subsequent elimination provided 4-diphenylmethylene
piperidine (71), which was hydrogenated to give 4-benz-
hydryl piperidine (73).Reductive amination of tert-butyl-
4-oxo-1-piperidinecarboxylate (75) with 4-isopropylani-
line and 3,4-dimethylaniline followed by N-alkylation
with 3,4-dimethyl benzyl chloride and 4-bromo-2-
As a continuation of our effort to optimize the receptor
binding affinity and antagonistic potency of the lead
antagonists, we have investigated the structure–activity
relationships in the C-region of N-(4-t-butylbenzyl)-N0-
[4-(methylsulfonylamino)benzyl]thiourea (2), in which
Figure 1.

J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
373
Scheme 1.
Scheme 2.
vitro antagonistic potencies of the compounds were
evaluated by measuring antagonism of the 45Ca2+
uptake induced by 50 nM capsaicin and expressed as the
KiÆSEM, respectively, correcting for competition by
capsaicin.All compounds were also evaluated as ago-
nists.Potencies as agonists were expressed as
EC50ÆSEM, and absolute levels of 45Ca2+ uptake were
compared with that induced by a maximally effective
concentration of capsaicin in this system, namely 300
nM.Receptor binding affinities were assessed in terms
of the ability of the compounds to compete for specific
binding of [3H]RTX in the CHO/VR1 system and were
expressed as the KiÆSEM.All values represent the
mean of at least three experiments.Determinations of
lack of effect represent the results of 1 or 2 experiments.
The results are summarized in Table 1.
Scheme 3.
methyl-2-butene produced the correponding four 4-dial-
kylamino piperidines (78–81).The coupling of the
prepared piperidines with isothiocyanate (5) afforded N-
(4-substituted piperidinyl) thioureas (72, 74, 86–89,
respectively).
One-carbon elongation of 4-t-butylbenzyl in the parent
antagonist (2), providing N-(4-t-butylphenylethyl)
thiourea (6), led to reduced potencies both in binding
affinity with a Ki=1260 nM (20-fold) and in antagonism
with an Ki=242 nM (4.5-fold). Since the 3,4-dimethyl-
phenylpropyl group is utilized as the C-region of DA-
5018, a capsaicinoid agonist currently under clinical
trials, 3,4-dimethylphenyl derivatives (7–9) were also
investigated and proved less potent than the corre-
sponding t-butylphenyl analogues.Their antagonism
decreased inversely as the carbon length of the linker
3. Results and discussion
The potencies and activities as agonists and antagonists
of the synthesized VR1 ligands were assessed in vitro by
a
45Ca2+ uptake assay, which was carried out using rat
VR1 heterologously expressed in Chinese hamster ovary
cells (CHO/VR1 cells) as previously described.29 The in

374
J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
Scheme 4.
Scheme 5.
increased.The result from these arylalkyl analogues
suggested that a short and compact lipophilic group,
rather than an extended group, appeared to be preferred
as a C-region for better binding ability and antagonism.
Replacement of the 4-t-butyl group in 2 with a tri-
fluoromethyl group produced compound 10 with mod-
estly reduced potency for binding [Ki=678 nM (11-
fold)] and for antagonism [Ki=308 nM (6-fold)].The N-
oleyl analogue (11), derived from olvanil, exhibited
dramatic loss in binding affinity and antagonism.This
finding confirmed that a linear-type group as a C-region
was not an appropriate candidate for VR1 antagonism,
at least as determined in our assay system.Isosteric
substitutions of the 4-t-butyl group in 2 were investi-
gated with iodo and several alkyne derivatives, such as
ethynyl (26), hexynyl (27), 2-phenylethynyl (28), and 2-
t-butylethynyl (29).The 4-iodo analogue ( 25) showed
significantly reduced binding affinity (ca.30-fold) and
antagonistic potency (6-fold) compared to the parent
compound.Furthermore, it showed partial agonism.
Polarized groups, such as the iodo and trifluoromethyl
groups, did not appear to be appropriate surrogates of
the 4-t-butyl group for binding and antagonism to VR1.
The alkyne analogues (26–29) displayed no antagonism
and very weak binding affinities, except for 29, which
had moderate activity.As a conformationally con-
strained analogue of the 4-t-butylphenyl group, the N-
(1-methylindan-5-yl) analogue (34) was examined and
Scheme 6.
displayed modestly reduced potency in binding affinity
with a Ki=359 nM (6-fold) and unaltered potency in
antagonism with an EC50=65.8 nM. We also investi-
gated N-(3,3-diarylpropyl) analogues as replacements
for the C-region because these groups provided excellent
analgesic activities although their in vitro results were
not available.33 However, their potencies did not exceed
that of the lead compound (1), and displayed moder-
ately reduced potencies both in binding affinities (6-fold
in 46, 4-fold in 47, 1.5-fold in 48 and 2-fold in 49) and
antagonism (4-fold in 46, 10-fold in 47, 2.5-fold in 48
and 7-fold in 49).Interestingly, their activity at the
receptor was susceptible to minor modification on
the benzene ring.Whereas the 4-methylphenyl analogue
(48) showed full antagonism with antagonistic potency
2-fold weaker than parent, the 3-methylphenyl analogue
(47) was a partial antagonist with 10-fold weaker
potency.The sensitivity of the agonistic/antagonistic
character to small variations was also observed in the
SAR of capsazepine surrogates.34
Resiniferatoxin (RTX) is an ultrapotent capsaicin ana-
logue with a binding potency approximately 4 orders of

J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
375
Scheme 7.
Scheme 8.

376
J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
Table 1. Potencies of vanilloid ligands for binding to rat VR1 and for inducing calcium influx in CHO/VR1 cells
Ki (nM) Binding affinity
EC50 (nM) Agonism
Ki (nM) Antagonism
Capsazepine
2
6
7
8
1300 (Æ150)
63 (Æ10)
NEa
NE
520 (Æ12)
53.9 (Æ8.7)
242 (Æ78)
630 (Æ120)
770 (Æ190)
NE
308 (Æ94)
12400 (Æ3900)
329 (Æ82)
NE
1260 (Æ310)
3120 (Æ120)
2090 (Æ570)
4000 (Æ1200)
678 (Æ92)
8200 (Æ2800)
2100 (Æ460)
8300 (Æ1900)
>10,000
NE
Weakb
NE
9
Weakb
NE
NE
10
11
25
26
27
28
29
34
46
47
48
49
57
58
59
61
63
65
67
72
74
86
87
88
89
Weakb
NE
NE
NE
NE
>10,000
NE
NE
NE
NE
1650 (Æ400)
359 (Æ61)
390 (Æ170)
256 (Æ67)
99 (Æ29)
419 (Æ53)
65.8 (Æ5.7)
204 (Æ57)
530 (Æ330)
135 (Æ16)
360 (Æ100)
NE
1460 (Æ380)
NE
NE
137 (Æ28)
>10,000
>4000
Weakb
NE
NE
NE
NE
NE
NE
NE
NE
NE
Weakb
NE
6000 (Æ940)
>10,000
>10,000
2066 (Æ91)
3700(Æ890)
7300 (Æ1400)
>10,000
NE
NE
6100 (Æ2100)
NE
NE
NE
NE
NE
NE
NE
weak
NE
>10,000
2000(Æ590)
>10,000
1900 (Æ360)
>10,000
a NE: not effective at 10 or 30 mM.
b Only fractional calcium uptake compared to 300 nM capsaicin (6, 15%; 9, 48%; 25, 22%; 58, 15%; 88: 20%).
magnitude greater than that of capsaicin.35 The compar-
ison of their structures powerfully argued that a more
complex pharmacophore of the C-region than that of
capsaicin could confer a marked enhancement in potency.
Based in part on previously published structure–activity
relationship studies on RTX,36 we have proposed four
functional groups, 4-hydroxy-3-methoxyphenyl, C20-
ester, C3-keto, and orthophenyl, as principal pharma-
cophores for interaction with the capsaicin binding site
of VR1.The orthophenyl group would reside in the
hydrophobic pocket occupied by the fatty chain in the
capsaicinoid.Interestingly, there are three oxygens next
to the orthophenyl group and they may establish some
polar interactions with the receptor.Recently, Appen-
dino et al.observed that 12-hydroxy (ricinoleyl vanilla-
mide, rinvanil) and 12-acetoxy (ricinoleyl vanillamide
12-acetate) analogues of olvanil showed increased effi-
cacy without greatly altered potency compared to olva-
nil.37 From that observation, they proposed that polar
elements might be present within the apolar pocket
accommodating the acyl residue of capsaicin.However,
this polar element would not establish a hydrogen bond
with the hydroxy of rinvanil, as evidenced by the
observation that its activity was significantly increased
by acetylation.These findings prompted us to explore
lipophilic groups containing heteroatoms capable of
interacting with polar elements in the C-region binding
site of the receptor.The 4- t-butylbenzyl group on the
lead antagonist (2) was substituted with 4-alkoxybenzyl
groups
such
as
4-(benzyloxy)benzyl,
4-(iso-
propoxy)benzyl and 4-butoxybenzyl to provide 57–59,
respectively.The N-(4-benzyloxy)benzyl analogue (57)
showed great reduction in binding affinity and agonism
(with very low potency) rather than antagonism.
Although the isopropoxy group of 58 has a similar size
compared to t-butyl, the binding potency of 58 was
reduced 100-fold compared to the parent compound.
This result suggested that the oxygen atom of the iso-
propoxy group might cause repulsive bumping with
hydrophobic groups in the binding site of the receptor,
resulting in the dramatic loss in binding affinity.
Appropriate position of the polar group in the C-region
is clearly important; the polar group was located remote
from the A,B-region in 12-hydroxy and 12-acetoxy
olvanil, both which showed potent agonism.37 The 4-
butoxybenzyl analogue (59) displayed no detectable
binding affinity or agonism/antagonism in this assay.
Nitrogen containing polar groups were also incorpo-
rated into the C-region.Several 4-substituted piperizine
and piperidine derivatives were investigated as surro-
gates of the 4-t-butylbenzyl group.The 4-phenyl ( 61), 4-
benzyl (63) and 4-diphenylmethyl (65) piperazine ana-
logues exhibited very weak binding affinities and lack of
agonism/antagonism.Similarly, 4-benzyl ( 67), 4-diphe-
nylmethylene (72) and 4-diphenylmethyl (74) piperidine
also showed almost complete loss of affinities for bind-
ing and agonism/antagonism.It is noteworthy that the

J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
377
4-nitrogen of piperazine provided rather favorable
binding because piperazine 63 and 65 had better binding
affinities than the corresponding piperidine analogues
67 and 74, respectively.Finally, 4-disubstituted amino
piperidine analogues (86–89) were prepared as struc-
tural combinations of 4-substituted piperazine and
4-alkylpiperidine.However, none of these analogues
displayed any significant agonism/antagonism and the
3-methyl-2-butenylamino piperidine analogues (86, 88)
showed only weak binding affinity.
combined organic layers were washed with H2O and
brine, dried over MgSO4, filtered, and the filtrate was
concentrated in vacuo.The residue was purified by flash
column chromatography on silica gel with EtOAc/hex-
anes as eluant.
4.2.3. N-(4-tert-Butylphenylethyl)-N0-[-4-(methylsulfony-
lamino)benzyl]thiourea (6). Compound 6 was prepared
by following the general procedure for thiourea synth-
esis (Method A) in 93% yield.: white solid, mp=58 ꢀC;
1H NMR (CDCl3) d 7.33 (d, 2H, J=8.3 Hz), 7.27 (d,
2H, J=8.3 Hz), 7.18 (d, 2H, J=8.3 Hz), 7.10 (d, 2H,
J=8.3 Hz), 6.32 (s, 1H, NHSO2), 5.70 (bs, 1H, NHCS),
5.60 (bs, 1H, NHCS), 4.56 (bs, 2H, NHCH2Ar), 3.72
(bs, 2H, NHCH2CH2Ar), 3.01 (s, 3H, SO2CH3), 2.86 (t,
2H, J=6.8 Hz, NHCH2CH2Ar), 1.31 (s, 9H, C(CH3)3);
MS (FAB) m/z 420 (MH+).Anal.calcd for
C21H29N3O2S2: C, 60.11; H, 6.97; N, 10.01; S, 15.28.
Found: C, 60.39; H, 7.00; N, 9.97; S, 15.24.
In conclusion, on the basis of the recent discovery of N-
(4-t-butylbenzyl)-N0 -[4-(methylsulfonylamino)benzyl]
thiourea (2) as a potent vanilloid receptor antagonist,
the structure–activity relationships of the C-region were
investigated on the template of N-[4-(methylsulfonyl-
amino)benzyl]thiourea, fixed as
A and B-regions.
Diverse surrogates including araalkyl, alkyl, 4-alky-
nylbenzyl, indanyl, 3,3-diarylpropyl, 4-alkoxybenzyl, 4-
substituted piperazine and piperidine were substituted
for the 4-t-butylbenzyl group of 2 in an effort to opti-
mize antagonism.However, none of synthesized com-
pounds showed any significant improvement in binding
affinity and antagonistic potency compared to 2.We
conclude that the 4-t-butylbenzyl group is so far one of
most favorable groups for receptor binding and antag-
onism as was similarly found in a series of capsaicinoid
agonists.
4.2.4. N-(3,4-Dimethylbenzyl)-N0-[-4-(methylsulfonylami-
no)benzyl]thiourea (7). Compound 7 was prepared by
following the general procedure for thiourea synthesis
(Method A) in 94% yield: white solid, mp=110 ꢀC; H
1
NMR (CDCl3) d 6.97–7.25 (m, 7H), 6.68 (s, 1H,
NHSO2), 6.20 (bs, 1H, NHCS), 6.01 (bs, 1H, NHCS),
4.65 (d, 2H, J=5.4 Hz, NHCH2), 4.51 (d, 2H, J=5.2
Hz, NHCH2), 3.00 (s, 3H, SO2CH3), 2.15–2.30 (m, 6H,
2ÂCH3); MS (FAB) m/z 378 (MH+).Anal.calcd for
C18H23N3O2S2: C, 57.27; H, 6.14; N, 11.13; S, 16.99.
Found: C, 57.49; H, 6.16; N, 11.09; S, 16.91.
4. Experimental
4.1. General method
4.2.5. N-(3,4-Dimethylphenylethyl)-N0-[-4-(methylsulfo-
nylamino)benzyl]thiourea (8). Compound 8 was pre-
pared by following the general procedure for thiourea
synthesis (Method A) in 92% yield: white solid,
All chemical reagents were commercially available.
Melting points were determined on a Melting Point
Buchi B-540 apparatus and are uncorrected.Silica gel
column chromatography was performed on silica gel 60,
230-400 mesh, Merck.Proton NMR spectra were
recorded on a JEOL JNM-LA 300 at 300 MHz.Che-
mical shifts are reported in ppm units with Me4Si as
a reference standard.Mass spectra were recorded on a
VG Trio-2 GC-MS.Combustion analyses were per-
formed on an EA 1110 Automatic Elemental Analyzer,
CE Instruments, and were within 0.4% of the calculated
values unless otherwise noted.
mp=134 ꢀC; H NMR (CDCl3) d 7.14–7.25 (m, 4H),
1
6.85–7.05 (m, 3H), 6.68 (s, 1H, NHSO2), 5.90 (bs, 1H,
NHCS), 5.80 (bs, 1H, NHCS), 4.55 (bs, 2H,
NHCH2Ar), 3.66 (bs, 2H, NHCH2CH2Ar), 3.00 (s, 3H,
SO2CH3), 2.93 (t, 1H, J=7 Hz, NHCH2CH2Ar), 2.82
(t, 1H, J=7 Hz, NHCH2CH2Ar), 2.2–2.3 (m, 6H,
2ÂCH3); MS (FAB) m/z 392 (MH+).Anal.calcd for
C19H25N3O2S2: C, 58.28; H, 6.44; N, 10.73; S, 16.38.
Found: C, 58.52; H, 6.47; N, 10.70; S, 16.32.
4.2.6. N-(3,4-Dimethylphenylpropyl)-N0-[-4-(methylsulfo-
nylamino)benzyl]thiourea (9). Compound 9 was pre-
pared by following the general procedure for thiourea
synthesis (Method A) in 94% yield: white solid,
mp=125–127 ꢀC; 1H NMR (CDCl3) d 7.28 (d, 2H,
J=8.3 Hz, 2H), 7.19 (d, 2H, J=8.3 Hz, 2H), 6.85–7.05
(m, 3H), 6.80 (s, 1H, NHSO2), 5.91 (bs, 2H, 2ÂNHCS),
4.56 (bs, 2H, NHCH2Ar), 3.38 (bs, 2H,
NHCH2CH2CH2Ar), 2.99 (s, 3H, SO2CH3), 2.59 (t, 2H,
J=7.3 Hz, NHCH2CH2CH2Ar), 2.20 (d, 6H, 2ÂCH3),
1.90 (m, 2H, NHCH2CH2CH2Ar); MS (FAB) m/z 406
(MH+).Anal.calcd for C 20H27N3O2S2: C, 59.23; H,
6.71; N, 10.36; S, 15.81. Found: C, 59.48; H, 6.74; N,
10.31; S, 15.76.
4.2. General procedure for thiourea synthesis
4.2.1. Method A. A solution of amine (1 mmol) was
treated with 4-(methylsulfonylamino)benzyl isothio-
cyanate (1 mmol, 242 mg) in CH2Cl2 (10 mL), stirred
overnight at room temperature and then concentrated
in vacuo.The residue was purified by flash column
chromatography on silica gel with EtOAc/hexanes as
eluant.
4.2.2. Method B. A solution of amine salt (1 mmol) in
DMF (5 mL) was treated with triethylamine (0.2 mL,
1.5 mmol) and 4-(methylsulfonylamino)benzyl iso-
thiocyanate (242 mg, 1 mmol), and stirred overnight at
room temperature.The reaction mixture was diluted
with H2O and extracted with EtOAc several times.The
4.2.7. N-(4-Trifluoromethylbenzyl)-N0-[-4-(methylsulfo-
nylamino)benzyl]thiourea (10). Compound 10 was pre-

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J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
pared by following the general procedure for thiourea
synthesis (Method A) in 90% yield: white solid,
mp=154 ꢀC; 1H NMR (DMSO-d6) d 9.66 (s, 1H,
NHSO2), 8.03 (bs, 2H, NHCS), 7.67 (d, 2H, J=8.0 Hz),
7.45 (d, 2H, J=7.8 Hz), 7.23 (d, 2H, J=7.8 Hz), 7.15
(d, 2H, J=8.0 Hz), 4.76 (bs, 2H, NHCH2), 4.61 (bs, 2H,
NHCH2), 2.94 (s, 3H, SO2CH3); MS (FAB) m/z 418
(MH+).Anal.calcd for C 17H18F3N3O2S2: C, 48.91; H,
4.35; N, 10.07; S, 15.36. Found: C, 49.25; H, 4.38; N,
10.03; S, 15.31.
copper(I) iodide (38 mg, 0.2 mmol) and dichlorobis
(triphenylphosphine)palladium (I) (70 mg, 0.1 mmol),
and stirred at room temperature for 3 h.The reaction
mixture was diluted with ether, filtered through Celite,
and the filtrate was concentrated in vacuo.The residue
was purified by flash column chromatography on silica
gel with EtOAc/hexanes (1:10) to afford 15 (721 mg,
99%) as a yellow solid: mp=95 ꢀC; 1H NMR (CDCl3) d
7.40 (d, 2H, J=8.0 Hz), 7.18 (d, 2H, J=8.0 Hz), 4.79
(bs, 1H, NH), 4.28 (d, 2H, J=5.1 Hz, CH2), 1.44 (s, 9H,
C(CH3)3), 0.23 (s, 9H, Si(CH3)3).
4.2.8.
N-Oleyl-N0-[-4-(methylsulfonylamino)benzyl]-
thiourea (11). Compound 11 was prepared by following
4.2.12. tert-Butyl N-(4-ethynylbenzyl)carbamate (16). A
solution of 15 (530 mg, 1.75 mmol) in THF (10 mL) was
treated with tetrabutylammonium fluoride (1.0 M, 3.5
mL, 3.5 mmol) and stirred at room temperature for 1 h.
After evaporation, the residue was purified by flash col-
umn chromatography on silica gel with EtOAc/hexanes
(1:5) as eluant to afford 16 (430 mg, 100%) as a white
solid: mp=82 ꢀC; 1H NMR (CDCl3) d 7.45 (d, 2H,
J=8.3 Hz), 7.23 (d, 2H, J=8.3 Hz), 4.85 (bs, 1H, NH),
4.31 (d, 2H, J=5.6 Hz, CH2), 3.06 (s, 1H, CHꢁC), 1.46
(s, 9H, C(CH3)3).
the general procedure for thiourea synthesis (Method
A) in 88% yield: white solid, mp=133 ꢀC; H NMR
1
(CDCl3) d 7.35 (d, 2H, J=8.3 Hz), 7.20 (d, 2H, J=8.3
Hz), 6.53 (s, 1H, NHSO2), 5.85 (bs, 1H, NHCS), 5.34
(m, 2H, CH=CH), 4.71 (bs, 2H, NHCH2), 3.32 (bs, 2H,
NHCH2CH2), 3.02 (s, 3H, SO2CH3), 2.00 (m, 4H,
CH2CH=CHCH2), 1.56 (m, 2H, NHCH2CH2), 1.25–
1.3 (m, 22H), 0.88 (t, 3H, CH3); MS (FAB) m/z 510
(MH+).Anal.calcd for C 27H47N3O2S2: C, 63.61; H,
9.29; N, 8.24; S, 12.58. Found: C, 63.90; H, 9.33; N,
8.20; S, 12.54.
4.2.13. tert-Butyl N-[4-(1-hexynyl)benzyl]carbamate
(17). Compound 17 was prepared from 1-hexyne by fol-
lowing the procedure described for the synthesis of 15 in
98% yield: yellow solid, mp=62 ꢀC; 1H NMR (CDCl3) d
7.35 (d, 2H, J=8.3 Hz), 7.19 (d, 2H, J=8.3 Hz), 4.81 (bs,
1H, NH), 4.29 (d, 2H, J=5.9 Hz, CH2NH), 2.40 (t, 2H,
J=7.1 Hz, C=CCH2), 1.45-1.65 (m, 4H, CH2CH2), 1.46
(s, 9H, C(CH3)3), 0.95 (t, 2H, J=7.3 Hz, CH3).
4.2.9. 4-Iodobenzyl azide (13). A solution of 4-iodo-
benzyl bromide (12) (1.485 g, 5 mmol) in DMF (5 mL)
was treated with sodium azide (0.975 g, 15 mmol) and
stirred at room temperature for 2 h.The reaction mix-
ture was diluted with H2O and extracted with EtOAc
several times.The combined organic layers were washed
with H2O and brine, dried over MgSO4, filtered, and the
filtrate was concentrated in vacuo.The residue was
purified by flash column chromatography on silica gel
with EtOAc/hexanes (1:10) as eluant to afford 13 (1.282
g, 99%) as a white solid: mp=36 ꢀC; 1H NMR (CDCl3)
d 7.70 (d, 2H, J=8.3 Hz), 7.06 (d, 2H, J=8.3 Hz), 4.29
(s, 2H, CH2).
4.2.14. tert-Butyl N-[4-(2-phenylethynyl)benzyl]carba-
mate (18). Compound 18 was prepared from phenyla-
cetylene by following the procedure described for the
synthesis of 15 in 98% yield: yellow solid, mp=136 ꢀC;
1H NMR (CDCl3) d 7.45–7.55 (m, 4H), 7.3–7.38 (m,
3H), 7.27 (d, 2H, J=8.3 Hz), 4.84 (bs, 1H, NH), 4.33 (d,
2H, J=5.6 Hz, CH2NH), 1.47 (s, 9H, C(CH3)3).
4.2.10. tert-Butyl N-(4-iodobenzyl)carbamate (14). A
solution of 13 (1.036 g, 4 mmol) in THF (25 mL) was
treated with triphenylphosphine (1.5 g, 4 mmol) and
H2O (0.36 g, 20 mmol). After being stirred overnight at
room temperature, the reaction mixture was con-
centrated in vacuo.The residue was dissolved in THF
(40 mL) and treated with triethylamine (1.115 mL, 8
mmol) and di-tert-butyl dicarbonate (1.746 mL, 8
mmol).After being stirred at room temperature for 3 h,
the reaction mixture was diluted with H2O and extrac-
ted with EtOAc several times.The combined organic
layers were washed with H2O and brine, dried over
MgSO4, filtered, and the filtrate was concentrated in
vacuo.The residue was purified by flash column chro-
matography on silica gel with EtOAc/hexanes (1:3) as
eluant to afford 14 (1.146 g, 86%) as a white solid:
4.2.15. tert-Butyl N-[4-(3,3-dimethyl-1-butynyl)benzyl]-
carbamate (19). Compound 19 was prepared from tert-
butylacetylene by following the procedure described for
the synthesis of 15 in 99% yield: yellow solid,
ꢀ
1
mp=103 C; H NMR (CDCl3) d 7.34 (d, 2H, J=8.3
Hz), 7.18 (d, 2H, J=8.3 Hz), 4.79 (bs, 1H, NH), 4.28 (d,
2H, J=5.6 Hz, CH2NH), 1.45 (s, 9H, C(CH3)3), 1.31 (s,
9H, CꢁCC(CH3)3).
4.2.16. 4-Iodobenzyl amine trifluoroacetate (20). A
cooled solution of 14 (333 mg, 1 mmol) in CH2Cl2 (5
mL) at 0 ꢀC was treated with trifluoroacetic acid (1 mL).
After being stirred at room temperature for 1 h, the
reaction mixture was evaporated.The residue was dilu-
ted with EtOAc and concentrated in vacuo several times
to afford 20 (330 mg, 95%) as white solid, which was
used for the next coupling with further purification:
mp=164 ꢀC; 1H NMR (acetone-d6) d 7.76 (d, 2H,
J=8.3 Hz), 7.32 (d, 2H, J=8.3 Hz), 4.98 (s, 2H, CH2).
mp=91 ꢀC; H NMR (CDCl3) d 7.65 (d, 2H, J=8.3
1
Hz), 7.03 (d, 2H, J=8.3 Hz), 4.85 (bs, 1H, NH), 4.25 (d,
2H, J=5.8 Hz, CH2), 1.45 (s, 9H, C(CH3)3).
4.2.11. tert-Butyl N-{4-[2-(trimethylsilyl)ethynyl]benzyl}-
carbamate (15). A solution of 14 (666 mg, 2 mmol) in
THF (20 mL) was treated with (trimethylsilyl)acetylene
(0.34 mL, 2.4 mmol), triethylamine (0.557 mL, 4 mmol),
4.2.17. 4-Ethynylbenzyl amine trifluoroacetate (21).
Compound 21 was prepared from 16 by following the

J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
379
procedure described for the synthesis of 20 in 98%
yield.: white solid, mp=182 ꢀC; 1H NMR (acetone-d6) d
7.50 (s, 4H), 5.03 (s, 2H, CH2), 3.69 (s, 1H, CHꢁC).
4.2.24. N-[4-(2-Phenylethynyl)benzyl]-N0-[4-(methylsulfo-
nylamino)benzyl]thiourea (28). Compound 28 was pre-
pared by following the general procedure for thiourea
synthesis (Method B) in 82% yield: white solid,
mp=197 ꢀC; 1H NMR (acetone-d6) d 7.25–7.6 (m, 13H,
Ar), 4.87 (d, 2H, J=6.1 Hz, NHCH2Ar), 4.79 (d, 2H,
J=5.9 Hz, NHCH2Ar), 2.95 (s, 3H, NHSO2CH3); IR
(KBr) 3435, 1627, 1550, 1324, 1136 cmÀ1; MS (FAB) m/
z 450 (MH+).Anal.calcd for C 24H23N3O2S2: C, 64.12;
H, 5.16; N, 9.35; S, 14.26. Found: C, 64.45; H, 5.13; N,
9.30; S,14.15.
4.2.18. 4-(1-Hexynyl)benzyl amine trifluoroacetate (22).
Compound 22 was prepared from 17 by following the
procedure described for the synthesis of 20 in 98%
yield: red solid, mp=160 ꢀC; H NMR (DMSO-d6) d
1
8.20 (bs, 3H, NH+3 ), 7.41 (m, 4H), 4.02 (d, 2H,
CH2NH+3 ), 2.42 (t, 2H, J=6.8 Hz, CꢁCCH2), 1.35–
1.55 (m, 4H, CH2CH2), 0.90 (t, 2H, J=7.1 Hz, CH3).
4.2.19. 4-(2-Phenylethynyl)benzyl amine trifluoroacetate
(23). Compound 23 was prepared from 18 by following
the procedure described for the synthesis of 20 in 88%
yield.: red solid, mp=185ꢀC; 1H NMR (DMSO-d6) d 8.17
(bs, 3H, NH3), 7.4–7.65 (m, 9H), 4.08 (bs, 2H, CH2NH+3 ).
4.2.25. N-[4-(3,3-Dimethyl-1-butynyl)benzyl]-N0-[4-(me-
thylsulfonylamino)benzyl]thiourea (29). Compound 29
was prepared by following the general procedure for
thiourea synthesis (Method B) in 88% yield: white solid,
mp=174 ꢀC; 1H NMR (acetone-d6) d 8.49 (bs, 1H,
NHSO2), 7.25–7.4 (m, 8H, Ar), 4.81 (d, 2H, J=5.6 Hz,
NHCH2Ar), 4.78 (d, 2H, J=5.6 Hz, NHCH2Ar), 2.95
(s, 3H, NHSO2CH3), 1.29 (s, 9H, C(CH3)3); IR (KBr)
3434, 3270, 2927, 1541, 1510, 1319, 1145 cmÀ1; MS
(FAB) m/z 430 (MH+).Anal.calcd for C 22H27N3O2S2:
C, 61.51; H, 6.33; N, 9.78; S, 14.93. Found: C, 61.58; H,
6.31; N, 9.80; S, 14.90.
4.2.20. 4-(3,3-Dimethyl-1-butynyl)benzyl amine trifluoro-
acetate (24). Compound 24 was prepared from 19 by
following the procedure described for the synthesis of 20
in 97% yield: brown solid, mp=180 ꢀC; 1H NMR
(DMSO-d6) d 8.00 (bs, 3H, NH3), 7.36 (d, 2H, J=7.3
Hz), 7.21 (d, 2H, J=7.3 Hz), 3.89 (bs, 2H, CH2NH+3 ),
1.29 (s, 9H, CꢁCC(CH3)3).
4.2.26. 5-Cyano-1-indanone (31). A solution of 5-bromo-
1-indanone (30) (200 mg, 0.95 mmol) in 1-methyl-2-
pyrrolidinone (2 mL) was treated with copper cyanide
(170 mg, 1.9 mmol) and heated at 140 ꢀC for 20 h.After
cooling, the mixture was directly purified by flash col-
umn chromatography on silica gel with EtOAc/hexanes
(1:3) as eluant to afford 31 (158 mg, 76%) as a crystal-
line yellowish solid: mp=128–130 ꢀC; 1H NMR
(CDCl3) d 7.84 (d, 1H, J=7.8 Hz, H-7), 7.81 (bs, 1H,
H-4), 7.66 (dd, 1H, J=7.8, 2 Hz, H-6), 3.22 (t, 2H,
J=5.8 Hz, H-3), 2.78 (m, 2H, H-2); IR (KBr) 2228
4.2.21.
N-(4-Iodobenzyl)-N0-[4-(methylsulfonylamino)-
benzyl]thiourea (25). Compound 25 was prepared by
following the general procedure for thiourea synthesis
(Method B) in 73% yield: white solid, mp=186 ꢀC; H
1
NMR (acetone-d6) d 8.52 (bs, 1H, NH), 7.68 (d, 2H,
J=8.2 Hz), 7.46 (bs, 1H, NH), 7.30 (m, 4H), 7.15 (d,
2H, J=8.0 Hz), 4.78 (m, 4H, CH2NHCSNHCH2), 2.96
(s, 3H, SO2CH3); IR (KBr) 3229, 1543, 1321, 1146
cmÀ1; MS (FAB) m/z 476 (MH+).Anal.calcd for
C16H18IN3O2S2: C, 40.43; H, 3.82; N, 8.84; S, 13.49.
Found: C, 40.62; H, 3.86; N, 8.80; S, 13.45.
(CN), 1714 (C¼O) cmÀ1
.
4.2.22. N-(4-Ethynylbenzyl)-N0-[4-(methylsulfonylamino)
benzyl]thiourea (26). Compound 26 was prepared by
following the general procedure for thiourea syꢀnthesis
4.2.27. 6-Cyano-3-methyl-1H-indene (32). A cooled
solution of 31 (100 mg, 0.64 mmol) in CH2Cl2 (2 mL) at
0 ꢀC was treated with trimethyl aluminum (0.96 mL,
2 M in hexanes, 1.92 mmol) followed by trimethylsilyl
trifluoromethanesulfonate (0.256 mL, 1.28 mmol) and
stirred for 3 h at room temperature.The mixture was
cooled, diluted with H2O, and extracted with ether sev-
eral times.The combined organic layer was con-
centrated and the residue was purified by flash column
chromatography on silica gel with EtOAc/hexanes (1:5)
as eluant to afford 32 (87 mg, 88%) as a colorless oil.:
1H NMR (CDCl3) d 7.69 (bs, 1H, H-7), 7.61 (dd, 1H,
J=7.8, 2 Hz, H-5), 7.38 (d, 1H, J=7.8 Hz, H-4), 6.44
(m, 1H, H-2), 3.37 (m, 2H, H-1), 2.18 (m, 3H, CH3).
1
(Method B) in 80% yield: white solid, mp=158 C; H
NMR (acetone-d6) d 7.54 (bs, 2H, NH), 7.2–7.5 (m,
8H), 4.84 (d, 2H, J=4.9 Hz, NHCH2Ar), 4.77 (d, 2H,
J=5.1 Hz, NHCH2Ar), 3.30 (s, 1H, CꢁCH), 2.93 (s,
3H, NHSO2CH3); IR (KBr) 2918, 1540, 1319, 1146
cmÀ1; MS (FAB) m/z 374 (MH+).Anal.calcd for
C18H19N3O2S2: C, 57.88; H, 5.13; N, 11.25; S, 17.17.
Found: C, 57.59; H, 5.18; N, 11.20; S, 17.13.
4.2.23. N-[4-(1-Hexynyl)benzyl]-N0-[4-(methylsulfonyla-
mino)benzyl]thiourea (27). Compound 27 was prepared
by following the general procedure for thiourea synth-
esis (Method B) in 70% yield: white solid, mp=161 ꢀC;
1H NMR (CDCl3) d 7.34 (d, 2H, J=8.0 Hz), 7.1–7.25
(m, 6H), 6.10 (bs, 1H, NH), 6.00 (bs, 1H, NH), 4.65 (d,
2H, J=5.1 Hz, NHCH2Ar), 4.61 (d, 2H, J=4.9 Hz,
NHCH2Ar), 2.99 (s, 3H, SO2CH3), 2.41 (t, 2H, J=6.8
Hz, CꢁCCH2), 1.4–1.7 (m, 4H, CH2CH2), 0.95 (t, 2H,
CH3); IR (KBr) 3436, 3239, 2931, 1634, 1553, 1323,
1147 cmÀ1; MS (FAB) m/z 430 (MH+).Anal.calcd for
C22H27N3O2S2: C, 61.51; H, 6.33; N, 9.78; S, 14.93.
Found: C, 61.27; H, 6.36; N, 9.75; S, 14.98.
4.2.28. (1-Methyl-indan-5-yl)methylamine hydrochloride
(33). A suspension of 32 (80 mg, 0.515 mmol) and 10%
palladium on carbon (40 mg) in MeOH (5 mL) was
treated with concentrated hydrochloric acid (2 drops)
and hydrogenated under a balloon of hydrogen over-
night.The mixture was filtered through Celite and the
filtrate was concentrated to afford 33 (94 mg, 92%) as a
white solid, which was used for the next step after
washing with ether several times: white solid, mp=198–
200 ꢀC; H NMR (CD3OD) d 7.2–7.3 (m, 3H, Ar), 4.05
1

380
J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
(s, 2H, CH2NH+3 ), 3.18 (m, 1H, H-1), 2.8–3.0 (m, 2H,
H-3), 2.34 (m, 1H, H-2a), 1.60 (m, 1H, H-2b), 1.26 (d,
3H, J=6.8 Hz, CH3).
yield: yellow oil; H NMR (CDCl3) d 6.95–7.4 (m, 9H,
Ar), 5.79 (bs, 1H, NH2), 5.49 (bs, 1H, NH2), 4.47 (t, 1H,
J=7.8 Hz, CH), 2.88 (d, 2H, J=7.8 Hz, CH2), 2.27 (s,
3H, CH3).
1
4.2.29. N-[(1-Methyl-indan-5-yl)methyl]-N0-[4-(methyl-
sulfonylamino)benzyl]thiourea (34). Compound 34 was
prepared by following the general procedure for
thiourea synthesis (Method B) in 52% yield: white solid,
mp=69–71ꢀC; 1H NMR (CDCl3) d 7.0–7.2 (m, 7H, Ar),
6.94 (bs, 1H, NHSO2), 6.30 (bs, 1H, NH), 6.12 (bs, 1H,
NH), 4.64 (d, 2H, J=5.1 Hz, CH2NH), 4.55 (d, 2H, J=5.0
Hz, CH2NH), 3.15 (m, 1H, H-1), 3.98 (s, 3H, SO2CH3),
2.7–2.9 (m, 2H, H-3), 2.30 (m, 1H, H-2a), 1.60 (m, 1H, H-
2b), 1.26 (d, 3H, J=6.8 Hz, CH3); IR (KBr) 3359, 2954,
1556, 1327, 1152 cmÀ1; MS (FAB) m/z 404 (MH+).Anal.
calcd for C20H25N3O2S2 : C, 59.52; H, 6.24; N, 10.41; S,
15.89. Found: C, 59.79; H, 6.28; N, 10.37; S, 15.84.
4.2.35. 3-(3,4-Dimethylphenyl)-3-phenyl-2-propanamide
(41). Compound 41 was prepared from 38 by following
the procedure described for the synthesis of 39 in 99%
yield: white solid; 1H NMR (CDCl3) d 6.95–7.3 (m, 8H,
Ar), 5.66 (bs, 1H, NH2), 5.45 (bs, 1H, NH2), 4.45 (t, 1H,
J=7.8 Hz, CH), 2.90 (d, 2H, J=7.8 Hz, CH2), 2.19 (s,
6H, 2ÂCH3).
4.2.36. 3-(3-Methylphenyl)-3-phenyl-2-propylamine (43).
A cooled solution of lithium aluminium hydride (190
mg, 5 mmol) in THF (5 mL) at 0 ꢀC was treated with a
solution of 39 (478 mg, 2 mmol) in THF (5 mL) drop-
wise.After being refluxed for 4 h, the reaction mixture
was cooled in ice-bath and treated by successive drop-
wise addition of H2O (0.2 mL), 15% NaOH solution
(0.4 mL), and H2O (0.6 mL). After additional stirring
for 30 min, the mixture was filtered by washing with
EtOAc and the filtrate was concentrated in vacuo.The
residue was purified by flash column chromatography
over silica gel with CH2Cl2/MeOH (10:1) as eluant to
afford 43 (347 mg, 77%) as a brown oil.: 1H NMR
(CDCl3) d 6.95–7.4 (m, 9H, Ar), 3.97 (t, 1H, J=7.8 Hz,
CH), 3.30 (bs, 2H, NH2), 2.68 (t, 2H, J=6.8 Hz,
CH2NH2), 2.1–2.3 (s, 5H, CHCH2 and CH3).
4.2.30. 3-(3-Methylphenyl)-3-phenyl-2-propenamide (36).
A mixture of cinnamamide (1 g, 6.8 mmol), 3-iodoto-
luene (1.927 g, 8.84 mmol), triethylamine (1.24 mL, 8.84
mmol), palladium(II) acetate (15 mg, 0.07 mmol) and tri-
O-tolylphosphine (83 mg, 0.27 mmol) in 1,2-dichloro-
benzene (15 mL) was heated at 120 ꢀC for 20 h.The
reaction mixture was diluted with water and extracted
with EtOAc several times.The combined organic layers
were washed with water, dried over Na2SO4, and con-
centrated in vacuo.The residue was purified by flash
column chromatography over silica gel with EtOAc/
hexanes (2:1) as eluant to afford 36 (1.614 g, 90%) as a
1
white solid. H NMR (CDCl3) d 7.1–7.5 (m, 9H, Ar),
6.38 (s, 1H, C=CH), 5.17 (bs, 1H, NH2), 5.00 (bs, 1H,
NH2), 2.35 (s, 3H, CH3).
4.2.37. 3-(4-Methylphenyl)-3-phenyl-2-propylamine (44).
Compound 44 was prepared from 40 by following the
procedure described for the synthesis of 43 in 89%
1
yield: yellow oil; H NMR (CDCl3) d 6.95–7.4 (m, 9H,
4.2.31. 3-(4-Methylphenyl)-3-phenyl-2-propenamide (37).
Compound 37 was prepared from 4-iodotoluene by fol-
lowing the procedure described for the synthesis of 36 in
98% yield: white solid; H NMR (CDCl3) d 7.0–7.5 (m,
9H, Ar), 6.38 (s, 1H, C=CH), 5.26 (bs, 1H, NH2), 5.04
(bs, 1H, NH2), 2.32 (s, 3H, CH3).
Ar), 3.97 (t, 1H, J=7.8 Hz, CH), 3.10 (t, 2H, NH2), 2.68
(t, 2H, J=6.8 Hz, CH2NH2), 2.1–2.3 (s, 5H, CHCH2
and CH3).
1
4.2.38. 3-(3,4-Dimethylphenyl)-3-phenyl-2-propylamine
(45). Compound 45 was prepared from 41 by following
the procedure described for the synthesis of 43 in 91%
1
4.2.32. 3-(3,4-Dimethylphenyl)-3-phenyl-2-propenamide
(38). Compound 38 was prepared from 4-iodo-o-xylene
by following the procedure described for the synthesis
yield: yellow oil; H NMR (CDCl3) d 6.95–7.3 (m, 8H,
Ar), 3.94 (t, 1H, J=7.8 Hz, CH), 2.65 (t, 2H, J=6.8 Hz,
CH2NH2), 2.1–2.2 (s, 8H, CHCH2, 2ÂCH3).
1
of 36 in 98% yield: white solid; H NMR (CDCl3) d
7.0–7.5 (m, 8H, Ar), 6.37 (s, 1H, C=CH), 5.23 (bs, 1H,
NH2), 5.01 (bs, 1H, NH2), 2.26 (s, 3H, CH3), 2.22 (s,
3H, CH3).
4.2.39. N-(3,3-Diphenylpropyl)-N0-[4-(methylsulfonylami-
no)benzyl]thiourea (46). Compound 46 was prepared by
following the general procedure for thiourea syꢀnthesis
1
(Method A) in 96% yield: white solid, mp=77 C; H
4.2.33. 3-(3-Methylphenyl)-3-phenyl-2-propanamide (39).
A suspension of 36 (1.186 g, 5 mmol) and 5% palladium
on carbon (100 mg) in MeOH (20 mL) was hydro-
genated under a balloon of hydrogen for 16 h.The
reaction mixture was filtered and the filtrate was con-
centrated in vacuo to afford 39 (1.16 g, 97%) as a white
solid, which was used for the next step without further
purification.: 1H NMR (CDCl3) d 6.95–7.4 (m, 9H, Ar),
5.18 (bs, 2H, NH2), 4.51 (t, 1H, J=7.8 Hz, CH), 2.94 (d,
2H, J=7.8 Hz, CH2), 2.30 (s, 3H, CH3).
NMR (acetone-d6) d 8.37 (s, 1H, NHSO2), 7.0–7.2 (m,
14H), 6.89 (bs, 2H, NHCS), 4.60 (d, 2H, J=5.6 Hz,
NHCH2Ar), 3.90 (t, 1H, J=7.8 Hz, Ph2CH), 3.33 (m,
2H, CH2CH2NH), 2.82 (s, 3H, SO2CH3), 2.28 (m, 2H,
CH2CH2NH); MS (FAB) m/z 454 (MH+).Anal.calcd
for C24H27N3O2S2: C, 63.55; H, 6.00; N, 9.26; S, 14.14.
Found: C, 63.68; H, 6.03; N, 9.23; S, 14.10.
4.2.40.
N-[3-(3-Methylphenyl)-3-phenylpropyl]-N0-[4-
(methylsulfonylamino)benzyl]thiourea (47). Compound
47 was prepared by following the general procedure for
thiourea synthesis (Method A) in 97% yield: white
solid, mp=73 ꢀC; 1H NMR (CDCl3) d 7.0–7.35 (m,
13H), 6.05 (bs, 2H, NHCS), 4.48 (bs, 2H, NHCH2Ar),
4.2.34. 3-(4-Methylphenyl)-3-phenyl-2-propanamide (40).
Compound 40 was prepared from 37 by following the
procedure described for the synthesis of 39 in 98%

J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
381
3.88 (t, 1H, J=7.8 Hz, Ar2CH), 3.35 (bs, 2H,
CH2CH2NH), 2.94 (s, 3H, SO2CH3), 2.25–2.3 (m, 5H,
CH2CH2NH and CH3); MS (FAB) m/z 468 (MH+).
Anal.calcd for C 25H29N3O2S2: C, 64.21; H, 6.25; N, 8.99;
S, 13.71. Found: C, 64.48; H, 6.22; N, 8.97; S, 13.66.
ane, and concentrated in vacuo.The residue was
triturated with ether and precipitated solid was filtered
to afford 54 (388 mg, 78%) as a white solid, which was
1
used in next step without any further purification: H
NMR (DMSO-d6) d 8.29 (bs, 2H, NH+3 ), 7.3–7.5 (m,
7H, Ar), 7.02 (d, 2H, J=8.5 Hz, Ar), 6.53 (s, 1H,
NH+3 ), 5.12 (s, 2H, PhCH2O), 3.92 (s, 2H, CH2NH+3 ).
4.2.41.
N-[3-(4-Methylphenyl)-3-phenylpropyl]-N0-[4-
(methylsulfonylamino)benzyl]thiourea (48). Compound
48 was prepared by following the general procedure for
thiourea synthesis (Method A) in 95% yield: white solid,
mp=68 ꢀC; 1H NMR (CDCl3) d 7.0–7.35 (m, 13H), 6.04
(bs, 2H, NHCS), 4.48 (bs, 2H, NHCH2Ar), 3.88 (t, 1H,
J=7.5 Hz, Ar2CH), 3.35 (bs, 2H, CH2CH2NH), 2.94 (s,
3H, SO2CH3), 2.25–2.30 (m, 2H, CH2CH2NH and CH3);
MS (FAB) m/z 468 (MH+).Anal.calcd for
C25H29N3O2S2: C, 64.21; H, 6.25; N, 8.99; S, 13.71.
Found: C, 64.40; H, 6.23; N, 8.95; S, 13.64.
4.2.47. 4-Isopropoxybenzylamine hydrochloride (55).
Compound 55 was prepared from 52 by following the
procedure described for the synthesis of 54 in 55%
1
yield: white solid; H NMR (DMSO-d6) d 8.14 (bs, 2H,
NH+3 ), 7.36 (d, 2H, J=8.3 Hz, Ar), 6.93 (d, 2H, J=8.3
Hz, Ar), 4.62 (m, 1H, CH(CH3)2), 3.91 (s, 2H,
CH2NH+3 ), 1.24 (d, 6H, J=5.8 Hz, CH(CH3)2).
4.2.48. 4-Butoxybenzylamine hydrochloride (56). Com-
pound 56 was prepared from 53 by following the proce-
dure described for the synthesis of 54 in 77% yield: white
solid; 1H NMR (DMSO-d6) d 8.21 (bs, 2H, NH+3 ), 7.37
(d, 2H, J=8.3 Hz, Ar), 6.94 (d, 2H, J=8.3 Hz, Ar), 3.9–
4.0 (m, 4H, OCH2 and CH2NH+3 ), 1.66 (m, 2H, CH2),
1.42 (m, 2H, CH2), 0.91 (t, 3H, J=7.3 Hz, CH3).
4.2.42. N-[3-(3,4-dimethylphenyl)-3-phenylpropyl]-N0-[4-
(methylsulfonylamino)benzyl]thiourea (49). Compound
49 was prepared by following the general procedure for
thiourea synthesis (Method A) ) in 96% yield: white
solid, mp=74 ꢀC; 1H NMR (CDCl3) d 7.15–7.3 (m,
9H), 6.9–7.05 (m, 3H), 5.96 (bs, 2H, NHCS), 4.47 (bs,
2H, NHCH2Ar), 3.85 (t, 1H, J=7.6 Hz, Ar2CH), 3.35
(bs, 2H, CH2CH2NH), 2.96 (s, 3H, SO2CH3), 2.31 (m,
2H, CH2CH2NH), 2.18 (d, 6H, J=4.4 Hz, 2ÂCH3); MS
(FAB) m/z 482 (MH+).Anal.calcd for C 26H31N3O2S2:
C, 64.83; H, 6.49; N, 8.72; S, 13.31. Found: C, 64.98; H,
6.46; N, 8.67; S, 13.29.
4.2.49. N-[4-(Benzyloxy)benzyl]-N0-[4-(methylsulfonyl-
amino)benzyl]thiourea (57). Compound 57 was prepared
by following the general procedure for thiourea synthesis
(Method B) in 72% yield.: white solid, mp=181ꢀC; H
1
NMR (acetone-d6) d 7.25–7.4 (m, 11H), 6.95 (d, 2H,
J=8.7 Hz), 5.10 (s, 2H, OCH2Ph), 4.77 (d, 2H, J=5.3 Hz,
NHCH2Ar), 4.71 (d, 2H, J=5.4 Hz, NHCH2Ar), 2.95 (s,
3H, NHSO2CH3); IR (KBr) 3435, 1552, 1138 cmÀ1
.
4.2.43. 4-Benzyloxybenzonitrile (51). A mixture of 4-
cyanophenol (50) (0.6 g, 5 mmol), potassium carbonate
(2.76 g, 20 mmol) and benzyl bromide (1.026 g, 6 mmol)
in acetone (20 mL) was refluxed for 5 h and evaporated.
The residue was diluted with CH2Cl2, washed with H2O,
dried over MgSO4, and concentrated in vacuo.The
residue was purified by flash column chromatography
over silica gel with EtOAc/hexanes (2:1) as eluant to
MS (FAB) m/z 456 (MH+).Anal.calcd for
C23H25N3O3S2: C, 60.63; H, 5.53; N, 9.22; S, 14.08.
Found: C, 60.45; H, 5.56; N, 9.17; S, 13.99.
4.2.50. N-(4-Isopropoxybenzyl)-N0-[4-(methylsulfonyla-
mino)benzyl]thiourea (58). Compound 58 was prepared
by following the general procedure for thiourea synthesis
1
afford 51 (1.025 g, 98%) as a white solid.: H NMR
(CDCl3) d 7.57 (d, 2H, J=8.3 Hz, Ar), 7.3–7.45 (m, 5H,
Ph), 7.01 (d, 2H, J=8.3 Hz, Ar), 5.11 (s, 2H, CH2Ph).
(Method B) in 70% yield: white solid, mp=143 ꢀC; H
1
NMR (acetone-d6) d 7.25–7.35 (m, 6H), 6.85 (d, 2H, J=8.5
Hz), 4.78 (d, 2H, J=4.6 Hz, NHCH2Ar), 4.70 (d, 2H,
J=5.3 Hz, NHCH2Ar), 4.58 (m, 1H, OCH(CH3)2), 2.95 (s,
3H, NHSO2CH3), 1.26 (d, 6H, J=6.1 Hz, CH(CH3)2).
4.2.44. 4-Isopropoxybenzonitrile (52). Compound 52 was
prepared from 2-bromopropane by following the pro-
cedure described for the synthesis of 51 in 84% yield:
white solid; 1H NMR (CDCl3) d 7.56 (d, 2H, J=8.3 Hz,
Ar), 6.91 (d, 2H, J=8.3 Hz, Ar), 4.62 (m, 1H,
CH(CH3)2), 1.36 (d, 6H, J=5.8 Hz, CH(CH3)2).
IR (KBr) 3428, 1551, 1138 cmÀ1; MS (FAB) m/z 408
(MH+).Anal.calcd for C 19H25N3O3S2: C, 55.99; H,
6.18; N, 10.31; S, 15.74. Found: C, 55.69; H, 6.18; N,
10.26; S, 15.82.
4.2.45. 4-Butoxybenzonitrile (53). Compound 53 was
prepared from butyl bromide by following the proce-
dure described for the synthesis of 51 in 85% yield:
white solid; 1H NMR (CDCl3) d 7.56 (d, 2H, J=8.3 Hz,
Ar), 6.94 (d, 2H, J=8.3 Hz, Ar), 4.00 (t, 2H, J=6.6 Hz,
OCH2), 1.78 (m, 2H, CH2), 1.50 (m, 2H, CH2), 0.98 (t,
3H, J=7.3 Hz, CH3).
4.2.51. N-(4-Butoxybenzyl)-N0-[4-(methylsulfonylamino)-
benzyl]thiourea (59). Compound 59 was prepared by fol-
lowing the general procedure for thiourea synthesis
(Method B) in 76% yield: white solid, mp=167ꢀC; H
1
NMR (acetone-d6) d 7.25–7.35 (m, 6H), 6.85 (d, 2H,
J=8.5 Hz), 4.76 (d, 2H, J=4.6 Hz, NHCH2Ar), 4.71 (d,
2H, J=5.3 Hz, NHCH2Ar), 3.96 (t, 2H, J=6.3 Hz,
OCH2), 2.95 (s, 3H, NHSO2CH3), 1.72 (m, 2H,
OCH2CH2), 1.48 (m, 2H, CH2CH3), 0.95 (t, 3H, CH3); IR
(KBr) 3432, 1551, 1139 cmÀ1; MS (FAB) m/z 422 (MH+).
Anal.calcd for C 20H27N3O3S2: C, 56.98; H, 6.46; N, 9.97;
S, 15.21. Found: C, 56.84; H, 6.48; N, 9.92; S, 15.20.
4.2.46. 4-Benzyloxybenzylamine hydrochloride (54). A
mixture of 51 (418 mg, 2 mmol) in THF (10 mL) was
treated with borane methylsulfide (2.0 M in THF, 1.1
mL, 2.2 mmol) and refluxed for 3 h. The reaction mix-
ture was cooled, treated with hydrochloric acid in diox-

382
J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
4.2.52. N-(4-Phenylpiperazinyl)-N0-[4-(methylsulfonyla-
mino)benzyl]thiourea (61). Compound 61 was prepared
by following the general procedure for thiourea synth-
esis (Method A) in 92% yield: white solid, mp=171 ꢀC;
1H NMR (DMSO-d6) d 9.58 (bs, 1H, NHSO2), 8.28 (t,
1H, J=5.1 Hz, NHCH2), 7.2–7.3 (m, 4H, Ph), 7.14 (d,
2H, J=8.0 Hz), 6.94 (d, 2H, J=8.0 Hz), 6.77 (t, 1H,
J=7.3 Hz), 4.75 (d, 2H, J=5.1 Hz, NHCH2), 3.96 (m,
4H, H-2,6), 3.18 (m, 4H, H-3,5), 2.94 (s, 3H, SO2CH3);
IR (KBr) 3400, 2917, 1384, 1151, 668 cmÀ1; MS (FAB)
m/z 405 (MH+).Anal.calcd for C 19H24N4O2S2: C,
56.41; H, 5.98; N, 13.85; S, 15.85. Found: C, 56.61; H,
5.95; N, 13.89; S, 15.79.
Hz, PhCH2), 1.84 (m, 1H, H-4), 1.72 (m, 2H, H-
3,5(eq)), 1.26 (m, 2H, H-3,5(ax)); MS (FAB) m/z 418
(MH+).Anal.calcd for C 21H27N4O2S2: C, 60.40; H,
6.52; N, 10.06; S, 15.36. Found: C, 60.57; H, 6.50; N,
10.00; S, 15.30.
4.2.57. N-(tert-Butoxycarbonyl) ethyl 4-piperidinecar-
boxylate (69). A mixture of ethyl isonipecotate (0.677
g, 3 mmol), di-tert-butyl dicarbonate (0.786 g, 3.6
mmol) and Na2CO3 (0.636 g, 6 mmol) was refluxed in
H2O/THF (10:4 mL) for 1 h.The reaction mixture was
then cooled and extracted with EtOAc several times.
The combined organic layers were washed with brine,
dried over MgSO4, and evaporated.The residue was
purified by flash column chromatography on silica gel
with EtOAc/hexanes (1:1) as eluant to afford 69 (0.741
4.2.53. N-(4-Benzylpiperazinyl)-N0-[4-(methylsulfonyla-
mino)benzyl]thiourea (63). Compound 63 was prepared
by following the general procedure for thiourea synthesis
(Method A) in 92% yield: white solid, mp=124–126 ꢀC;
1H NMR (CDCl3) d 7.15–7.4 (m, 9H, Ar), 6.45 (bs, 1H,
NHSO2), 5.65 (bt, 1H, NHCH2), 4.87 (d, 2H, J=5.1 Hz,
NHCH2), 3.83 (t, 4H, J=5.1 Hz, H-2,6), 3.54 (s, 2H,
PhCH2N), 3.01 (s, 3H, SO2CH3), 2.50 (t, 4H, J=5.1 Hz,
H-3,5); MS (FAB) m/z 419 (MH+).Anal.calcd for
C20H26N4O2S2: C, 57.39; H, 6.26; N, 13.39; S, 15.32.
Found: C, 57.21; H, 6.22; N, 13.34; S, 15.28.
1
g, 96%) as a colorless oil: H NMR (CDCl3) d 4.14 (q,
2H, J=7.3 Hz, CO2CH2CH3), 4.02 (bd, 2H, J=11.5
Hz, H-2,6(eq)), 2.83 (bt, 2H, J=11.5 Hz, H-2,6(ax)),
2.43 (m, 1H, H-4), 1.82–1.92 (m, 2H, H-3,5(eq)), 1.55–
167 (m, 2H, H-3,5(ax)), 1.46 (s, 9H, C(CH3)3), 1.26 (t,
3H, J=7.3 Hz, CO2CH2CH3).
4.2.58. N-(tert-Butoxycarbonyl) 4-[hydroxy(diphenyl)me-
thyl]piperidine (70). A cooled solution of 69 (0.741 g,
2.88 mg) in benzene at 0 ꢀC was treated dropwise
with phenyl magnesium bromide (1 M in THF, 8.84
mL, 8.64 mmol) over 10 min and stirred for 1 h at
room temperature.The reaction mixture was quen-
ched with aqueous NH4Cl solution and extracted with
ether several times.The combined organic layers were
washed with brine, dried over MgSO4, and evaporated
to afford 70 (0.847 g, 80%) as a white solid. mp=192–
4.2.54. 1-Benzhydrylpiperazine (64). To a solution of
benzhydrol (1 g, 5.43 mmol) in CH2Cl2 (10 mL) was
slowly added thionyl chloride (0.48 mL, 6.51 mmol).
The mixture was stirred for 2 h at room temperature
and then concentrated in vacuo.The residue was dis-
solved in acetonitrile (10 mL) and then piperazine (2.3
g, 27.15 mmol) was added. After being stirred overnight
at 70 ꢀC, the mixture was concentrated and partitioned
into CH2Cl2-1N NaOH.The organic phase was col-
lected, dried over MgSO4, filtered and the filtrate was
concentrated to afford 64 (1.1 g, 80%) as a yellow solid,
which was washed with ether andꢀthen used for the next
coupling: white solid, mp=54–57 C; 1H NMR (CDCl3)
d 7.05–7.5 (m, 10H, 2ÂPh), 4.17 (s, 1H, Ph2CHN), 2.78
(t, 4H, J=4.9 Hz, H-2,6), 2.30 (bs, 4H, H-3,5).
194 ꢀC; H NMR (CDCl3) d 7.15–7.5 (m, 10H, 2ÂPh),
1
4.12 (bs, 2H, H-2,6(eq)), 2.83 (t, 2H, J=12.2 Hz, H-
2,6(ax)), 2.55 (m, 1H, H-4), 2.12 (s, 1H, OH), 1.2–1.55
(m, 4H, H-3,5), 1.42 (s, 9H, C(CH3)3); MS (FAB) m/z
368 (MH+).
4.2.59. 4-(Diphenylmethylene)piperidine (71). A mixture
of 70 (0.856 g, 2.33 mmol) and trifluoroacetic acid (8
mL) in CH2Cl2 (8 mL) was stirred for 16 h at room
temperature and then concentrated.The residue was
diluted with 1 N NaOH solution and extracted with
CH2Cl2 several times.The combined organic layers
were washed with brine, dried over MgSO4, and con-
centrated in vacuo to afford 71 (0.574 g, 98%) as a
4.2.55. N-(4-Benzhydrylpiperazinyl)-N0-[4-(methylsulfonyl-
amino)benzyl]thiourea (65). Compound 65 was prepared
by following the general procedure for thiourea synth-
esis (Method A) in 98% yield: white solid, mp=87–
89 ꢀC; H NMR (CDCl3) d 7.05–7.4 (m, 14H, Ar), 5.89
!
ꢀ
(t, 1H, J=5.1 Hz, NHCH2), 4.80 (d, 2H, J=5.1 Hz,
NHCH2), 4.22 (s, 1H, Ph2CHN), 3.78 (m, 4H, H-2,6),
2.92 (s, 3H, SO2CH3), 2.41 (m, 4H, H-3,5); IR (KBr)
3391, 1538, 1323, 1151, 750 cmÀ1; MS (FAB) m/z 495
(MH+).Anal.calcd for C 26H30N4O2S2: C, 63.13; H,
6.11; N, 11.33; S, 12.96. Found: C, 62.98; H, 6.10; N,
11.28; S, 12.89.
white solid.mp=77–78 C; 1H NMR (CDCl3) d 7.1–7.3
(m, 10H, 2ÂPh), 2.91 (t, 4H, J=5.6 Hz, H-2,6), 2.33 (t,
4H, J=5.6 Hz, H-3,5), 2.21 (bs, 1H, NH).
4.2.60. N-[4-(Diphenylmethylene)piperidinyl]-N0-[4-(me-
thylsulfonylamino)benzyl]thiourea (72). Compound 72
was prepared by following the general procedure for
thiourea synthesis (Method A) in 98% yield: white
4.2.56. N-(4-Benzylpiperidyl)-N0-[4-(methylsulfonylami-
no)benzyl]thiourea (67). Compound 67 was prepared by
following the general procedure for thiourea synthesis
(Method A) in 92% yield.: white solid, mp=162–
solid, mp=92–95 ꢀC; H NMR (CDCl3) d 7.1–7.35 (m,
1
14H, Ar), 6.71 (s, 1H, NHSO2), 5.69 (t, 1H, J=4.9 Hz,
NHCH2), 4.87 (d, 2H, J=4.9 Hz, NHCH2), 3.86 (t, 4H,
J=5.8 Hz, H-2,6), 2.99 (s, 3H, SO2CH3), 2.53 (t, 4H,
J=5.8 Hz, H-3,5); IR (KBr) 3268, 2917, 1614, 1537,
1324, 1152 cmÀ1; MS (FAB) m/z 492 (MH+).Anal.
calcd for C27H29N3O2S2 : C, 65.96; H, 5.95; N, 8.55; S,
13.04. Found: C, 66.12; H, 5.91; N, 8.49; S, 12.98.
164 ꢀC; H NMR (CDCl3) d 7.1–7.4 (m, 9H, Ar), 5.64
1
(bt, 1H, NHCH2), 4.86 (d, 2H, J=5.1 Hz, NHCH2),
4.59 (d, 2H, J=12.7 Hz, H-2,6(eq)), 3.02 (s, 3H,
SO2CH3), 2.96 (m, 2H, H-2,6(ax)), 2.56 (d, 2H, J=6.8

J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
383
4.2.61. 4-Benzhydrylpiperidine (73). A suspension of 72
(0.57 g, 2.82 mmol) and 5% palladium on carbon (0.5 g)
in MeOH (50 mL) was hydrogenated under a pressure
of 40 psi for 30 h.The reaction mixture was filtered
through Celite and the filtrate was concentrated in
vacuo to afford 73 as a colorless oil, which was used for
the next step without further purification.: 1H NMR
(CDCl3) d 7.1–7.3 (m, 10H, 2ÂPh), 3.48 (d, 1H, J=11 Hz,
CHPh2), 2.84 (dd, 2H, H-2,6(eq)), 2.24 (s, 1H, NH), 2.07
(m, 1H, H-4), 1.89 (t, 2H, J=11.7 Hz, H-2,6(ax)), 1.53 (t,
2H, J=13.4 Hz, H-3,5(eq)), 1.25 (m, 2H, H-3,5(ax)).
ethylamine (0.7 mL, 4 mmol) in THF (6 mL) was trea-
ted with 4-bromo-2-methyl-2-butene (0.23 mL, 2 mmol)
and refluxed for 4 h.The mixture was evaporated, dilu-
ted with H2O and extracted with EtOAc several times.
The combined organic layers were washed with brine,
dried over MgSO4, and evaporated.The residue was
purified by flash column chromatography on silica gel
with EtOAc/hexanes (1:5) as eluant to afford 78 (317
mg, 82%) as a white solid: mp=107–108 ꢀC; H NMR
1
(CDCl3) d 7.08 (d, 2H, J=8.6 Hz, Ar), 6.68 (d, 2H,
J=8.6 Hz, Ar), 5.10 (m, 1H, >C=CH), 4.20 (bs, 2H,
H-2,6(eq)), 3.76 (d, 2H, J=5.1 Hz, >C=CCH2N), 3.68
(m, 1H, H-4), 2.7-2.85 (m, 3H, H-2,6(ax) and CHMe2),
1.78 (bd, 2H, J=11.7 Hz, H-3,5(eq)), 1.68 (s, 6H,
(CH3)2C=C), 1.56 (m, 2H, H-3,5(ax)), 1.47 (s, 9H,
C(CH3)3), 1.21 (d, 6H, J=6.8 Hz, CH(CH3)2).
4.2.62. N-(4-Benzhydrylpiperidinyl)-N0-[4-(methylsulfonyl-
amino)benzyl]thiourea (74). Compound 74 was prepared
by following the general procedure for thiourea synth-
esis (Method A) in 96% yield.: white solid, mp=104–
107 ꢀC; 1H NMR (CDCl3) d 7.1–7.35 (m, 14H, Ar), 6.67
(s, 1H, NHSO2), 5.66 (t, 1H, J=5.2 Hz, NHCH2), 4.84
(d, 2H, J=5.2 Hz, NHCH2), 4.53 (d, 2H, J=13.4 Hz,
H-2,6(eq)), 3.48 (d, 1H, J=11 Hz, Ph2CH), 3.00 (m, 2H,
H-2,6(ax)), 2.98 (s, 3H, SO2CH3), 2.40 (m, 1H, H-4),
1.62 (m, 2H, H-3,5(eq)), 1.24 (m, 2H, H-3,5(ax)); IR
(KBr) 3398, 2917, 1539, 1322, 1151, 754 cmÀ1; MS
(FAB) m/z 494 (MH+).Anal.calcd for C 27H31N3O2S2 :
C, 65.69; H, 6.33; N, 8.51; S, 12.99. Found: C, 65.88; H,
6.30; N, 8.48; S, 12.93.
4.2.66. N-(tert-Butoxycarbonyl) 4-[N-(3,4-dimethylben-
zyl)-N-(4-isopropylphenyl)amino]piperidine (79). A solu-
tion of 76 (318 mg,
1
mmol) and N,N-
diisopropylethylamine (0.87 mL, 5 mmol) in DMF (5
mL) was treated with 3,4-dimethylbenzyl chloride (0.43
mL, 3 mmol) and heated at 100 ꢀC for 18 h.The mixture
was diluted with H2O and extracted with EtOAc several
times.The combined organic layers were washed with
brine, dried over MgSO4, and evaporated.The residue
was purified by flash column chromatography on silica
gel with EtOAc/hexanes (1:5) as eluant to afford 79 (375
4.2.63. N-(tert-Butoxycarbonyl) 4-(4-isopropylanilino)
piperidine (76). A mixture of 4-isopropylaniline (0.15
mL, 1.1 mmol), tert-butyl-4-oxo-1-piperidinecarbox-
ylate (75) (200 mg, 1 mmol) and 4 A molecular sieve
(400 mg) in CH2Cl2 (5 mL) was stirred for 30 min and
then treated with NaBH(OAc)3 (318 mg, 1.5 mmol).
After being stirred for 2 h at room temperature, the
reaction mixture was diluted with aqueous NaHCO3
solution and extracted with EtOAc several times.The
combined organic layers were washed with brine, dried
over MgSO4, and evaporated.The residue was purified
by flash column chromatography on silica gel with
EtOAc/hexanes (1:2) as eluant to afford 14 (300 mg,
94%) as a white solid: mp=100–101 ꢀC; 1H NMR
(CDCl3) d 7.04 (d, 2H, J=8.5 Hz, Ar), 6.55 (d, 2H,
J=8.5 Hz, Ar), 4.02 (bd, 2H, J=10.2 Hz, H-2,6(eq)),
3.39 (bs, 2H, H-4 and NH), 2.92 (t, 2H, J=11.5 Hz, H-
2,6(ax)), 2.80 (m, 1H, CHMe2), 2.02 (bd, 2H, J=13.2
Hz, H-3,5(eq)), 1.46 (s, 9H, C(CH3)3), 1.32 (m, 2H, H-
3,5(ax)), 1.20 (d, 6H, J=6.8 Hz, CH(CH3)2).
1
mg, 86%) as a colorless oil.: H NMR (CDCl3) d 7.0–
7.08 (m, 5H, Ar), 6.66 (d, 2H, J=8.8 Hz, Ar), 6.59 (d,
2H, J=8.8 Hz, Ar), 4.33 (d, 2H, J=12.7 Hz, NCH2Ar),
4.19 (bs, 2H, H-2,6(eq)), 3.86 (m, 1H, H-4), 2.7–2.85 (m,
3H, H-2,6(ax) and CHMe2), 2.2–2.3 (m, 6H, 2ÂCH3),
1.84 (bd, 2H, J=11 Hz, H-3,5(eq)), 1.5–1.6 (m, 2H, H-
3,5(ax)), 1.44 (s, 9H, C(CH3)3), 1.19 (d, 6H, J=6.8 Hz,
CH(CH3)2).
4.2.67. N-(tert-Butoxycarbonyl) 4-[N-(3,4-dimethylphe-
nyl)-N-(3-methyl-2-butenyl)amino]piperidine (80). Com-
pound 80 was prepared from 77 by following the
procedure described for the synthesis of 78 in 81%
ꢀ
1
yield.: white solid, mp=94–95 C; H NMR (CDCl3) d
6.96 (d, 1H, J=7.8 Hz, Ar), 6.56 (d, 1H, J=2.4 Hz, Ar),
6.50 (dd, 1H, J=7.8, 2.4 Hz, Ar), 5.08 (m, 1H,
>C=CH), 4.19 (bs, 2H, H-2,6(eq)), 3.74 (d, 2H, J=4.9
Hz, >C=CCH2N), 3.64 (m, 1H, H-4), 2.76 (t, 2H,
J=12.2 Hz, H-2,6(ax)), 2.18 (d, 6H, 2ÂCH3), 1.78 (bd,
2H, J=12.2 Hz, H-3,5(eq)), 1.68 (d, 6H, (CH3)2C=C),
1.55 (m, 2H, H-3,5(ax)), 1.46 (s, 9H, C(CH3)3).
4.2.64. N-(tert-Butoxycarbonyl) 4-(3,4-dimethylanilino)-
piperidine (77). Compound 77 was prepared from 3,4-
dimethylaniline by following the procedure described
for the synthesis of 76 in 93% yield.: white solid,
4.2.68. N-(tert-Butoxycarbonyl) 4-[N-(3,4-dimethylben-
zyl)-N-(3,4-dimethylphenyl)amino]piperidine (81). Com-
pound 81 was prepared from 77 by following the
procedure described for the synthesis of 79 in 91%
mp=119 ꢀC; H NMR (CDCl3) d 6.93 (d, 1H, J=7.8
1
Hz, Ar), 6.43 (d, 1H, J=2.4 Hz, Ar), 6.38 (dd, 1H,
J=7.8, 2.4 Hz, Ar), 4.02 (bd, 2H, J=10.2 Hz, H-
2,6(eq)), 3.36 (m, 2H, H-4 and NH), 2.91 (t, 2H, J=11.5
Hz, H-2,6(ax)), 2.16 (d, 6H, 2ÂCH3), 2.02 (bd, 2H,
J=13.2 Hz, H-3,5(eq)), 1.46 (s, 9H, C(CH3)3), 1.2–1.45
(m, 2H, H-3,5(ax)).
1
yield: colorless oil; H NMR (CDCl3) d 6.9–7.1 (m, 4H,
Ar), 6.4–6.6 (m, 2H, Ar), 4.32 (d, 2H, J=12 Hz,
NCH2Ar), 4.20 (bs, 2H, H-2,6(eq)), 3.85 (m, 1H, H-4),
2.78 (t, 2H, J=12.2 Hz, H-2,6(ax)), 2.15–2.3 (m, 12H,
4ÂCH3), 1.81 (bd, 2H, J=12.2 Hz, H-3,5(eq)), 1.55 (m,
2H, H-3,5(ax)), 1.42 (s, 9H, C(CH3)3).
4.2.65. N-(tert-Butoxycarbonyl) 4-[N-(4-isopropylphe-
nyl)-N-(3-methyl-2-butenyl)amino]piperidine (78).
solution of 76 (318 mg, 1 mmol) and N,N-diisopropyl-
A
4.2.69. 4-[N-(4-Isopropylphenyl)-N-(3-methyl-2-butenyl)
amino]piperidine (82). A solution of 78 (318 mg, 1

384
J. Lee et al. / Bioorg. Med. Chem. 12 (2004) 371–385
mmol) in CH2Cl2 (12 mL) was treated with tri-
fluoroacetic acid (3 mL) and stirred for 1 h at room tem-
perature.The mixture was concentrated in vacuo, diluted
with 1 N NaOH solution and extracted with CH2Cl2
several times.The combined organic layers were washed
with brine, dried over MgSO4, and evaporated.The
residue was purified by flash column chromatography on
silica gel with EtOAc/hexanes (2:1) as eluant to afford 82
1.21 (d, 6H, J=6.8 Hz, CH(CH3)2); IR (KBr) 3391,
2957, 1613, 1515, 1325, 1154 cmÀ1; MS (FAB) m/z 529
(MH+).Anal.calcd for C 28H40N4O2S2: C, 63.60; H,
7.62; N, 10.60; S, 12.13. Found: C, 63.78; H, 7.59; N,
10.56; S, 12.09.
4.2.74. N-{4-[N-(3,4-Dimethylbenzyl)-N-(4-isopropylphe-
nyl)amino]piperidinyl} -N0 -[4-(methylsulfonylamino)ben-
zyl]thiourea (87). Compound 87 was prepared by
following the general procedure for thiourea synthesis
(Method A) in 89% yield: white solid, mp=105–108 ꢀC;
1H NMR (CDCl3) d 7.32 (d, 2H, J=8.5 Hz, Ar), 7.17
(d, 2H, J=8.5 Hz, Ar), 6.95–7.15 (m, 3H, Ar), 6.68 (d,
2H, J=8.8 Hz, Ar), 6.61 (d, 2H, J=8.8 Hz, Ar), 6.47
(bs, 1H, NHSO2), 5.64 (t, 1H, J=4.6 Hz, NHCH2), 4.83
(d, 2H, J=4.6 Hz, NHCH2), 4.70 (d, 2H, J=12.9 Hz,
H-2,6(eq)), 4.32 (d, 2H, J=12.2 Hz, ArCH2N), 4.00 (m,
1H, H-4), 3.09 (t, 2H, J=12.7 Hz, H-2,6(ax)), 3.00 (s,
3H, SO2CH3), 2.80 (m, 1H, CHMe2), 2.32 (s, 1H), 2.22
(s, 5H, 2ÂCH3), 1.96 (m, 2H, H-3,5(eq)), 1.65 (m, 2H,
H-3,5(ax)), 1.20 (d, 6H, J=6.8 Hz, CH(CH3)2); IR
(KBr) 3392, 2955, 1612, 1514, 1322, 1152, 753 cmÀ1; MS
(FAB) m/z 579 (MH+).Anal.calcd for C 32H42N4O2S2:
C, 66.40; H, 7.31; N, 9.68; S, 11.08. Found: C, 66.63; H,
7.28; N, 9.64; S, 11.02.
1
(223 mg, 78%) as a colorless oil: H NMR (CDCl3) d
7.91 (bs, 1H, NH), 7.09 (d, 2H, J=8.6 Hz, Ar), 6.69 (d,
2H, J=8.6 Hz, Ar), 5.09 (m, 1H, >C=CH), 3.78 (d,
2H, J=5.1 Hz, >C=CCH2N), 3.70 (m, 1H, H-4), 3.38
(bd, 2H, H-2,6(eq)), 2.75–2.95 (m, 3H, H-2,6(ax) and
CHMe2), 1.8–1.95 (m, 4H, H-3,5), 1.68 (s, 6H,
(CH3)2C=C), 1.21 (d, 6H, J=6.8 Hz, CH(CH3)2).
4.2.70. 4-[N-(3,4-Dimethylbenzyl)-N-(4-isopropylphenyl)
amino]piperidine (83). Compound 83 was prepared
from 79 by following the procedure described for the
1
synthesis of 82 in 92% yield: colorless oil; H NMR
(CDCl3) d 8.2 (bs, 1H, NH), 7.0–7.1 (m, 5H, Ar), 6.67
(d, 2H, J=8.8 Hz, Ar), 6.58 (d, 2H, J=8.8 Hz, Ar), 4.35
(d, 2H, J=7.1 Hz, NCH2Ar), 3.92 (m, 1H, H-4), 3.40
(d, 2H, J=12.4 Hz, H-2,6(eq)), 2.94 (m, 2H, H-2,6(ax)),
2.80 (m, 1H, CHMe2), 2.15–2.3 (m, 6H, 2ÂCH3), 1.9–
2.1 (m, 4H, H-3,5), 1.19 (d, 6H, J=6.8 Hz, CH(CH3)2).
4.2.75. N-{4-[N-(3,4-Dimethylphenyl)-N-(3-methyl-2-bu-
tenyl)amino]piperidinyl}-N0-[4-(methylsulfonylamino)ben-
zyl]thiourea (88). Compound 88 was prepared by
following the general procedure for thiourea synthesis
(Method A) in 93% yield: white solid, mp=163–164 ꢀC;
1H NMR (CDCl3) d 7.34 (d, 2H, J=8.5 Hz, Ar), 7.19
(d, 2H, J=8.5 Hz, Ar), 6.97 (m, 2H, Ar), 6.5–6.6 (m,
2H, Ar and NHSO2), 5.78 (t, 1H, J=4.9 Hz, NHCH2),
5.05 (m, 1H, >C=CH), 4.86 (d, 2H, J=4.9 Hz,
NHCH2), 4.71 (d, 2H, J=13.4 Hz, H-2,6(eq)), 3.7–3.85
(m, 3H, C=CHCH2N and H-4), 3.09 (t, 2H, J=12.4
Hz, H-2,6(ax)), 3.01 (s, 3H, SO2CH3), 2.22 (s, 3H, CH3),
2.16 (s, 3H, CH3), 1.88 (m, 2H, H-3,5(eq)), 1.6–1.75 (m,
8H, H-3,5(ax) and CH=C(CH3)2); IR (KBr) 3391,
2918, 1612, 1510, 1324, 1152, 753 cmÀ1; MS (FAB) m/z
515 (MH+).Anal.calcd for C 27H38N4O2S2: C, 63.00;
H, 7.44; N, 10.88; S, 12.46. Found: C, 63.25; H, 7.42; N,
10.85; S, 12.21.
4.2.71. 4-[N-(3,4-Dimethylphenyl)-N-(3-methyl-2-butenyl)
amino]piperidine (84). Compound 84 was prepared
from 80 by following the procedure described for the
1
synthesis of 82 in 96% yield: colorless oil; H NMR
(CDCl3) d 6.96 (d, 1H, J=7.8 Hz, Ar), 6.57 (d, 1H,
J=2.4 Hz, Ar), 6.50 (dd, 1H, J=7.8, 2.4 Hz, Ar), 5.29
(bs, 1H, NH), 5.08 (m, 1H, >C=CH), 3.77 (d, 2H,
J=5.1 Hz, >C=CCH2N), 3.64 (m, 1H, H-4), 3.27 (d,
2H, J=12.2 Hz, H-2,6(eq)), 2.78 (bt, 2H, H-2,6(ax)),
2.18 (d, 6H, 2ÂCH3), 1.7–1.9 (m, 4H, H-3,5), 1.68 (d,
6H, (CH3)2C=C).
4.2.72. 4-[N-(3,4-Dimethylbenzyl)-N-(3,4-dimethylphenyl)
amino]piperidine (85). Compound 85 was prepared
from 81 by following the procedure described for the
1
synthesis of 82 in 92% yield.: colorless oil; H NMR
(CDCl3) d 6.9–7.1 (m, 4H, Ar), 6.4–6.6 (m, 2H, Ar),
4.34 (d, 2H, J=6.8 Hz, NCH2Ar), 3.87 (m, 1H, H-4),
3.32 (b, 2H, J=12.7 Hz, H-2,6(eq)), 2.87 (m, 2H, H-
2,6(ax)), 2.1–2.3 (m, 12H, 4ÂCH3), 1.8–2.0 (m, 4H, H-
3,5).
4.2.76. N-{4-[N-(3,4-Dimethylbenzyl)-N-(3,4-dimethyl-
phenyl)amino]piperidinyl}-N0 -[4-(methylsulfonylamino)-
benzyl]thiourea (89). Compound 89 was prepared by
following the general procedure for thiourea synthesis
(Method A) in 92% yield: white solid, mp=93–95 ꢀC;
1H NMR (CDCl3) d 7.30 (d, 2H, J=8.3 Hz, Ar), 7.16
(d, 2H, J=8.3 Hz, Ar), 6.9–7.1 (m, 3H, Ar), 6.76 (s, 1H,
Ar), 6.4–6.6 (m, 2H, Ar), 5.73 (t, 1H, J=5.1 Hz,
NHCH2), 4.82 (d, 2H, J=5.1 Hz, NHCH2), 4.69 (d, 2H,
J=12.9 Hz, H-2,6(eq)), 4.30 (d, 2H, J=10.2 Hz,
ArCH2N<), 3.98 (m, 1H, H-4), 3.08 (t, 2H, J=13.2 Hz,
H-2,6(ax)), 2.97 (s, 3H, SO2CH3), 2.22 (s, 5H, 2ÂCH3),
2.18 (s, 3H, CH3), 2.14 (s, 3H, CH3), 1.94 (m, 2H, H-
3,5(eq)), 1.50 (m, 2H, H-3,5(ax)); IR (KBr) 3392, 2919,
1612, 1509, 1322, 1152 cmÀ1; MS (FAB) m/z 565
(MH+).Anal.calcd for C 31H40N4O2S2: C, 65.92; H,
7.14; N, 9.92; S, 11.35. Found: C, 66.13; H, 7.11; N,
9.87; S, 11.30.
4.2.73. N-{4-[N-(4-Isopropylphenyl)-N-(3-methyl-2-bute-
nyl)amino]piperidinyl}-N0 -[4-(methylsulfonylamino)ben-
zyl]thiourea (86). Compound 86 was prepared by
following the general procedure for thiourea synthesis
(Method A) in 95% yield: white solid, mp=72–74 ꢀC;
1H NMR (CDCl3) d 7.33 (d, 2H, J=8.5 Hz, Ar), 7.19
(d, 2H, J=8.5 Hz, Ar), 7.08 (d, 2H, J=8.8 Hz, Ar), 6.76
(bs, 1H, NHSO2), 6.69 (d, 2H, J=8.8 Hz, Ar), 5.78 (t,
1H, J=4.9 Hz, NHCH2), 5.07 (m, 1H, >C=CH), 4.86
(d, 2H, J=4.9 Hz, NHCH2), 4.72 (d, 2H, J=13.4 Hz,
H-2,6(eq)), 3.7–3.85 (m, 3H, C=CHCH2N and H-4),
3.08 (t, 2H, J=12.2 Hz, H-2,6(ax)), 3.00 (s, 3H,
SO2CH3), 2.81 (m, 1H, CHMe2), 1.89 (m, 2H, H-
3,5(eq)), 1.6–1.75 (m, 8H, H-3,5(ax) and >C(CH3)2),

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