New polyamine-sensitive inhibitors of the NMDA receptor: Syntheses and pharmacological evaluation

Article abstract of DOI:10.1016/j.ejmech.2006.09.017

Derivatives of 5-(4-aminobutyl)-2-thiophene-octylamine, a potent polyamine-sensitive inhibitor of the NMDA receptor, were synthesized and evaluated as inhibitors of [³H]MK-801 binding to rat brain membranes. Alkylations of the terminal amino groups reduced inhibitory potency; only incorporation of the amino group of the short 4-aminobutyl arm into a piperidine ring was tolerated. Substitution of the thiophene nucleus with methyl or ethyl, and its replacement by a benzene nucleus, was of minor influence. The corresponding diguanidines exhibited high potency independent of chain length, whereas their sensitivity to spermine was sharply dependent on chain length. Insertion of an amide bond into the long octylamine arm increased sensitivity to spermine and to Tris buffer. Our results indicate that spermine sensitivity of [³H]MK-801 binding inhibition is responsive to subtle changes in inhibitor structure and represents a promising target for pharmaceutical research.

Full text of DOI:10.1016/j.ejmech.2006.09.017

European Journal of Medicinal Chemistry 42 (2007) 175e197
http://www.elsevier.com/locate/ejmech
Original article
New polyamine-sensitive inhibitors of the NMDA receptor: Syntheses
and pharmacological evaluation
Thomas Pohler a,c, Oliver Schadt c, Daniela Niepel a, Patrick Rebernik b,
¨
a,c
Michael L. Berger b, , Christian R. Noe
*
a Department of Medicinal Chemistry, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria
b Center for Brain Research, Medical University Vienna, Spitalgasse 4, A-1090 Vienna, Austria
c Department of Pharmaceutical Chemistry, Johann Wolfgang Goethe University, D-60439 Frankfurt/Main, Germany
Received 24 December 2005; received in revised form 18 September 2006; accepted 18 September 2006
Available online 15 November 2006
Abstract
Derivatives of 5-(4-aminobutyl)-2-thiophene-octylamine, a potent polyamine-sensitive inhibitor of the NMDA receptor, were synthesized and
evaluated as inhibitors of [3H]MK-801 binding to rat brain membranes. Alkylations of the terminal amino groups reduced inhibitory potency;
only incorporation of the amino group of the short 4-aminobutyl arm into a piperidine ring was tolerated. Substitution of the thiophene nucleus
with methyl or ethyl, and its replacement by a benzene nucleus, was of minor influence. The corresponding diguanidines exhibited high potency
independent of chain length, whereas their sensitivity to spermine was sharply dependent on chain length. Insertion of an amide bond into the
long octylamine arm increased sensitivity to spermine and to Tris buffer. Our results indicate that spermine sensitivity of [3H]MK-801 binding
inhibition is responsive to subtle changes in inhibitor structure and represents a promising target for pharmaceutical research.
Ó 2006 Elsevier Masson SAS. All rights reserved.
Keywords: Polyamine inverse agonist; NMDA receptor; 1,12-Diaminododecane; Spermine; Thiophene
1. Introduction
diaminododecane (1, Table 4) and arcaine (a diguanidine) ap-
pear to counteract this effect (inverse polyamine agonists)
[3e5]; thus, they seem to block the NMDA receptor complex
via the same mechanism as protons do. At higher concentra-
tions, polyamines and inverse polyamine agonists additionally
act as direct NMDA channel blockers [6e9]. Allosteric inhib-
itors, e.g. Ifenprodil, increase the sensitivity of the NMDA
receptor complex to inhibition by protons [10]; they achieve
this effect by interaction with a site which is not a direct target
of polyamines. Our search for polyamine inverse agonists with
increased potency started with a study of long chain diamines
with various chain lengths [5]. To introduce an additional site
for target interaction, we interrupted the carbon chain with
a thiophene nucleus. By placing the nucleus specifically
between the fourth and the fifth carbon atom of 1, we arrived
at 5-(4-aminobutyl)-2-thiophene-octylamine (2, Table 1) [11],
one of the most potent compounds of this class
(IC50 ¼ 0.3 mM). Here we document in detail the syntheses
The glutamate receptor of the NMDA type is an ion chan-
nel with high Ca2þ permeability, its conductance critically
depending on partial depolarization [1]. By virtue of these
properties, NMDA receptors not only play a crucial role in
synaptic plasticity, but also convey a dangerous threat to neu-
rons, since prolonged NMDA receptor stimulation, as it may
occur in stroke, epilepsy, or neurological conditions as Chorea
Huntington, can result in Ca2þ overload. The endogenous
polyamines spermidine and spermine increase frequency and
burst length of NMDA-induced currents in rat hippocampal
neurons, due to relief from a partial block by protons,
even at physiological pH [2]. Compounds like 1,12-
* Corresponding author. Tel.: þ431 4277 62892; fax: þ431 4277 62899.
E-mail address: michael.berger@meduniwien.ac.at (M.L. Berger).
0223-5234/$ - see front matter Ó 2006 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2006.09.017

176
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
Table 1
Influence of N-alkylation on the potency of 2 as inhibitor of [3H]MK-801 binding (50 mM Tris buffer)
R3
R3
R1
R1
N
N
N
R2
S
S
NH2
N
S
R4
R4
H2N
2,5d,5e,5f,5g,5h
12,11a,11b
16
100 spermineb
a
R1
R2
R3
R4
IC50 (mM)
nH
2
H
CH3
H
H
H
0.54 ꢀ 0.18 (31)
5.30 ꢀ 0.94 (6)
358 ꢀ 86 (4)
1.15 ꢀ 0.10 (28)
1.17 ꢀ 0.16 (5)
1.43 ꢀ 0.25 (3)
0.90, 1.00 (2)
1.20, 1.08 (2)
2.21, 2.00 (2)
1.09 ꢀ 0.09 (3)
1.03, 0.95 (2)
1.19 ꢀ 0.19 (3)
1.49 ꢀ 0.24 (3)
8.84 ꢀ 3.94 (24)
7.70 ꢀ 4.96 (6)
2.79 ꢀ 0.67 (4)
2.98, 3.81 (2)
6.57, 7.75 (2)
0.98, 2.12 (2)
9.07 ꢀ 1.71 (3)
8.58, 10.9 (2)
7.67 ꢀ 5.94 (4)
2.96 ꢀ 0.91 (3)
5d
5e
5f
H
CH3
CH3
C3H7
H
CH3
C3H7
CH3
H
CH3
H
114, 147 (2)
5g
5h
12
11a
11b
16
a
CH2]CHCH2
PhCH2
H
CH2]CHCH2
PhCH2
H
H
13.3 ꢀ 1.7 (3)
17.7, 8.67 (2)
0.63 ꢀ 0.06 (3)
2.48, 2.87 (2)
15.2 ꢀ 3.7 (4)
1.13 ꢀ 0.43 (3)
H
H
H
H
H
H
e
H
e
CH3
CH3
H
H
e
H
CH3
H
Hill coefficient.
Attenuation in the presence of 100 mM spermine.
b
of various structural analogues of 2 and their effect on
spermine-stimulated [3H]MK-801 binding. Studies on the
structure/activity relationships (SARs) of this type of com-
pounds are of high interest, since the polyamine modulatory
site of the NMDA receptor may offer a means to influence
this receptor (e.g. to provide neuroprotection) without the risks
associated with full NMDA agonists (that may induce sei-
zures) or direct blockers of the NMDA channel (like phency-
clidine) that may induce psychosis. Our results allow
delineation in more detail of the structural requirements for
addressing the polyamine regulatory site of the NMDA recep-
tor with pharmaceutical agents.
2. Chemistry
N,N-Substituted thiophene-dialkyldiamines 5aeh, 5k
(Scheme 1) were synthesized from dicarboxylic acids as de-
scribed [11]. To generate the corresponding diamides, gaseous
amines were applied as such to the acid chlorides (method A),
whereas liquid amines were coupled by method B (with the Mu-
kaiyama reagent [12]). From the diamides, the desired diamines
were obtained by LiAlH4-reduction (method C) [11]. The termi-
nal amine functions were extended to guanidine residues under
mild conditions with a Boc-protected guanylating reagent [13],
resulting in protected guanidines (Scheme 2). Purification of the
n
X
Y
R1 R2 R3 R4
3a
3b
3c
3k
4a
4b
4c
4d
4e
4f
3
3
3
2
3
3
3
3
3
3
3
3
2
3
3
3
3
3
3
3
3
2
Me
H
H
Me
Et
H
-
-
-
-
-
-
-
-
X
n
Y
Y
H
-
-
-
-
O
O
O
H
-
-
-
-
OH
HO
S
S
Me
H
H
H
H
H
Me
H
H
H
H
H
H
H
Me
H
H
H
H
3a-c
Me
Et
H
H
A
B
H
H
H
Me Me Me Me
X
n
H
H
Pro
All
Bz
H
H
H
H
H
H
H
H
H
Pro
All
Bz
H
H
H
H
H
H
H
H
H
O
4g
4h
4k
5a
5b
5c
5d
5e
5f
H
H
R3
R1
R1
N
N
R2
H
H
R4
H
H
4a-h
C
Me
H
H
H
H
Me
Et
H
H
H
H
H
H
X
n
Y
H
Me
Me
H
H
Me Me Me Me
R3
N
N
R2
H
H
Pro
All
Bz
H
H
H
H
H
Pro
All
Bz
H
H
H
H
H
S
5a-h
R4
5g
5h
5k
H
H
H
H
H
H
Scheme 1. Minor modifications of 2,5-thiophene-dialkyldiamines. Reagents and conditions: method A: THF/oxalyl chloride/bubbling with gaseous amine. Method
B: DCM/Mukaiyama reagent/TEA/liquid amine. Method C: THF/LiAlH4 for 5aeh, TFA/Et3SiH for 5k.

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
177
11b were accessible as described for 2 [11], but the synthesis
of the primary amine 12 required a specific protecting group
strategy, reacting amine 8c to sulfonamide 9c, followed by
FriedeleCrafts acylation and WolffeKishner reduction [11].
Scheme 4 gives an overview of the synthetic pathways lead-
ing to diamines with other aromatic rings inserted into the chain.
The benzylamine derivative 16 was synthesized as described for
2 [11], but using Clemmensen instead of WolffeKishner reduc-
tion. The synthesis of the symmetric diamine 20 started with 2-
fold FriedeleCrafts acylation of dithienylmethane 17 [14] with
succinyl chloride monoethylester, and continued as described
[11]. The synthesis of the phenyl analogue 24 started with the
ester 21. Here, the reduction (from 22 to 23, see Scheme 4)
was achieved by ionic deoxygenation in TFA/Et3SiH [15,16].
The increased potency of 2 in comparison to aliphatic homo-
logues could be due to the p-donor functionality in the chain.
With 28 we synthesized a structurally related compound pro-
viding such a functionality without an aromatic ring. The syn-
thetic route (Scheme 5) started with the alkyne 25 [17],
accessible from 1,4-butandiol. Linkage with THP-protected
8-bromo-octanol by nucleophilic displacement under basic
conditions in THF/hexamethyl phosphoric acid triamide re-
sulted in 26. THP-deprotection and mesylation were followed
m,n:
3,8
4,8
2,6
3,7
2
5i
5j
5k
NH2
H2N
S
n
m
i)
Boc
HN
H
N
H
N
H
N
6i
6j
6k
6
m S
ii)
n
Boc
N
N
Boc
H2N
Boc
H
N
H
N
n
NH2
NH
7
7i
7j
7k
S
m
NH
Scheme 2. 2,5-Thiophene-dialkyldiguanidines. Reagents and conditions: (i)
MeCN/guanylating reagent; (ii) 3 M HCl/AcOEt. [Compound number]: inter-
mediate of synthesis, not isolated.
protected tetra-Boc-guanidines 6 and 6iek by column chroma-
tography and deprotection under acid conditions resulted in the
HCl salts of the diguanidines 7 and 7iek.
As a further side chain modification, we studied the effect
of structural integration of the short arm amino group into a pi-
peridine ring (Scheme 3). The N-methyl derivatives 11a and
X
N
ii
H
N
Y
S
S
S
8
8
O
O
8a: X = CH3; Y = COOEt
[8b]: X = CH3; Y = CH3
[8c]: X = H; Y = H
9c
i
i
O
O
O
N
O
X
N
H
N
N
Y
S
S
8
S
8
O
O
O
O
10c
10a: X = CH3; Y = COOEt
10b: X = CH3; Y = CH3
iii
iii
HN
HN
X
N
H
N
Y
S
S
S
8
8
O
O
11a: X = CH3; Y = H
11b: X = CH3; Y = CH3
11c
iv
HN
NH2
8
S
12
Scheme 3. Piperidine containing analogues 11a, 11band 12. Reagentsand conditions: (i)4-chlorocarbonyl-piperidine carboxylicacidethyl ester/AlCl3/DCE; (ii)2,4,6-
Me3-benzene-SO2Cl/NEt3/DCM; (iii) KOH/N2H4$H2O/ethylene glycol; (iv) Na/naphthaline/DME. [Compound number]: intermediate of synthesis, not isolated.

178
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
O
O
S
S
S
S
S
S
6
MeO
17
21
O
13
i
i
i
O
O
O
O
O
O
O
O
OEt
OH
6
O
O
EtO
OEt
6
MeO
HO
18
22
O
O
O
O
O
14
O
O
HO
HO
C
B
A
O
6
MeO
OMe
S
6
S
S
S
S
23
19
15
NH2
6
NH2
S
16
6
H2N
NH2
H2N
20
24
H2N
Scheme 4. Aromatic diamines 16, 20 and 24. Reagents and conditions: (i) acid chloride/anhydride/AlCl3/DCE; (A) Zn/HClconc/toluene/H2O; (B) N2H4$H2O/KOH/
ethylene glycol; (C) TFA/Et3SiH. Arrow horde: steps have been described earlier [11].
by nucleophilic attack with sodium azide in MeOH. The result-
ing diazide 27 was finally subjected to tin chloride reduction.
Finally, we studied the effect of inserting heteroatoms into
the carbon backbone of the long arm of thiophene-dialkyldi-
amines. Introduction of two oxygens, in addition to the increase
in polarity, was expected to increase rigidity of the long arm
(due to steric gauche alignment). The first ether bond was
formed with 2-(2-thienyl)ethanol 29 [18] and THP-protected
bromo-ethanol in dry DMF with NaH (Scheme 6). After
THP-deprotection, the second ether oxygen was introduced
with bromo-acetic acid and NaH in dry THF. After this critical
step, the final diether 32 was accessible as described [11].
The two amides 35a and 35b made accessible the corre-
sponding polyamines 36a and 36b, with nitrogen atoms in-
serted into the carbon backbone of the long arm of 2
(Scheme 7). The precursor mono-Boc-protected thiophene-di-
alkyldiamines 34a and 34b were coupled with the amino acid
constructs N-a-Boc-alanine and N-a-Boc-glycineeglycine, re-
spectively (active ester coupling). Boc-deprotection under
acidic conditions yielded 35a and 35b, with one or two amide
bonds in the long arm, and reduction with LiAlH4 in THF
yielded the corresponding polyamines 36a and 36b. Other
compounds with amide insertion (38aed, 39 and 40) were
synthesized by solid phase amino acid coupling, using nitro-
phenylcarbonate-activated WangÒ resin [19] or trityl chloride
resin. The resin-coupled amine was subjected to amino acid
active ester coupling (Scheme 8), using HOBt as coupling re-
agent [20]. For synthesis of 42, the amide-interrupted analogue
of 1, mono-Boc-protected 1,8-diaminooctane [21] was cou-
pled with Boc-protected b-alanine (as described for 4feh),
and deprotected (as described for 35a).
O
O
25
i
O
O
O
O
26
6
ii,iii,iv
+
N
N
N
+
N
N
N
6
6
27
3. Pharmacology
v
Specific binding of [3H]MK-801 to rat brain membranes
[22] allows the distinction from each other of positive and
negative modulators of the ion channel associated with the
NMDA receptor, data otherwise accessible in living cells
only. Polyamines and polyamine agonists increase the opening
frequency of the channel and thereby the accessibility of the
binding site for [3H]MK-801, located in the depth of the
H2N
NH2
28
Scheme 5. The alkyne diamine 28. Reagents and conditions: (i) 2-(8-Br-octy-
loxy)-THP/n-BuLi/THF/hexamethyl phosphoric acid triamide; (ii) toluene-
4-sulfonic acid/MeOH; (iii) MeSO2Cl/DCM/TEA; (iv) NaN3/MeOH; (v)
SnCl2/PhSH/TEA.

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
179
channel [6e9]. Inhibition at the glutamate or at the glycine site
would have been masked by the high excess of the co-agonists
added (10 mM each; the EC50 for glycine is 40 nM and that for
glutamate even lower [23]).
OH
O
S
S
29
30
31
i,ii
OH
O
4. Results
iii
4.1. Alkylation of the amino groups
O
The potency of many pharmaceuticals is improved by in-
creasing lipophilicity. Therefore, we were interested in N-alky-
lated derivatives of 2. However, already 5d was 10-fold
weaker than the parent compound (Table 1), and 5e was al-
most inactive. Also the N,N0-propyl derivative 5f was a very
weak inhibitor, whereas the analogous derivatives with allyl
5g and with benzyl 5h acted only slightly weaker than meth-
ylated 5d. If the amino group of the long octylamine arm was
free as in the piperidine analogue 12 and the benzylamine an-
alogue 16, potency was preserved. In the short aminobutyl
arm, the secondary amino group resulting from formation of
a piperidine ring was better tolerated than methylation (com-
pare 11a to 5d). The feasibility of annulating rings to the short
arm of 2 is demonstrated by the encouraging potency of 16.
However, inhibition by this benzylamine was only slightly
influenced by spermine (Table 1, last column). Spermine sen-
sitivity comparable to the parent compound was observed with
the secondary diamine 5d, with the piperidines 12, 11a and
11b and, surprisingly, with the allyl derivative 5g.
O
OH
S
O
H2N
O
NH2
S
32
Scheme 6. The diether 32. Reagents and conditions: (i) 2-(4-Br-butoxy)-THP/
NaH/DMF; (ii) toluene-4-sulfonic acid/MeOH; (iii) NaH/THF/BrCH2COOH.
Arrow horde: steps have been described earlier [11].
channel. If low nanomolar concentrations of the radioligand
are used (we used 5 nM), specific binding of [3H]MK-801
increases with the opening frequency of the channel. An inhib-
itor of [3H]MK-801 binding is likely to act as an inverse poly-
amine agonist, if its potency is markedly reduced in the
presence of 10e100 mM spermine, since it competes with
spermine for the same site, and since 10e100 mM spermine
are high concentrations relative to the EC50 of spermine
(2e3 mM [3e5]). The attenuation factors achieved depend
on buffer concentration and other factors, and meaningful in-
formation is only obtained if several compounds are compared
to each other under identical conditions. Many compounds ex-
hibit mixed inhibitory properties, acting at the polyamine site
and e especially at higher concentrations e also directly at the
4.2. Modifications at the central nucleus
We decided for a thieno nucleus to be inserted into the carbon
chain [11] due to the high expertise of one of us in thiophene
chemistry [24]. There was no specific reason to prefer this
H
N
Boc
4
OH
S
33
H
N
H
N
Boc
4
Boc
4
NH2
NH2
S
34b
S
34a
iii, iv
i, ii
O
O
H
N
H2N
H2N
H2N
NH2
NH2
4
N
H
S
35b
4
N
H
NH2
NH2
S
35a
O
v
v
H
N
H2N
4
N
H
4
N
H
S
36a
S
36b
Scheme 7. Synthesis of peptide and polyamine derivatives. Reagents and conditions: (i) Mukaiyama reagent, AcOEt, TEA, Boc-b-alanine; (ii) TFA/DCM; (iii)
DIC/HOBt/DMF/Boc-Gly-Gly; (iv) TFA/H2O; (v) LiAlH4/THF; Arrow horde: -OH converted to -NH2 via -I and N3 [31].

180
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
R1
CH3
H
R2
H
CH3
H
R3
H
H
H
38a
38b
38c
38d
39
H
N
O
O
4
4
NH
R3
S
Ph
s
o
l
O
O
H
Ph
H
H
CH2Ph
CH2Ph
i
i
O
R1
R1
O
H
N
d
N
N
H
O
S
R3 R2
p
h
a
s
e
ii
O
O
R1
H
N
iv
O
O
H2N
4
N
NH2
NH2
4
N
S
S
O
O
R3 R2
R3 R2
r
e
s
i
38a-d, 39
iii
iv
H
N
n
H2N
4
N
NH2
4
N
NH2
S
S
40
Scheme 8. Solid phase syntheses. Reagents and conditions: (i) protected amino acid in DMF/DIC/HOBt; (ii) piperidine/DMF; (iii) BH3/THF, 1,8-diazabicy-
clo[5.4.0]undec-7-en in MeOH/N-methylpyrrolidinone; (iv) TFA/DCM.
nucleus to any other. Now we show that the benzene analogue 24
did almost as well as the parent compound 2 (Table 2). However,
if the aminobutyl and the octylamine arms of 2 were joined to-
gether by two carbon atoms connected by a triple bond (also rich
in p-electrons), the resulting alkyne 28 was not more potent than
the corresponding saturated alkyldiamine (1,14-diaminotetra-
decane, 37 [5], Table 2). Substituting the parent compound 2
in position 3 or 4 of the thieno ring with methyl or ethyl resulted
in the slightly less potent analogues 5aec (Table 2).
4.3. Modifications in the octylamine arm of 2
While insertion of a second thieno ring was tolerated (20,
Table 3), all other attempts to insert heteroatoms into the
Table 2
Influence of modifications at the central nucleus on the potency of 2 as inhibitor of [3H]MK-801 binding (50 mM Tris buffer)
a
nH
Structure
IC50 (mM)
100 spermineb
NH2
37
28
5.28 ꢀ 1.23 (6)
1.23 ꢀ 0.05 (3)
6.94 ꢀ 1.45 (4)
H2N
8
4
NH
8
2
8.25, 6.73 (2)
1.14, 1.03 (2)
5.38, 5.90 (2)
H2N
4
NH
8
2
24
2
0.87 ꢀ 0.12 (3)
1.29 ꢀ 0.11 (3)
7.95 ꢀ 0.91 (3)
H2N
H2N
4
4
0.54 ꢀ 0.18 (31)
1.08, 1.97 (2)
1.62, 2.66 (2)
1.15 ꢀ 0.10 (28)
1.19, 1.93 (2)
1.25, 1.17 (2)
8.84 ꢀ 3.94 (24)
4.98, 4.07 (2)
5.84, 3.90 (2)
NH2
8
S
5a
5b
H2N
H2N
NH2
4
4
S
S
8
NH2
8
5c
3.29, 3.23 (2)
1.12, 1.00 (2)
2.67, 3.11 (2)
H2N
NH2
4
S
8
a
Hill coefficient.
Attenuation in the presence of 100 mM spermine.
b

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
181
Table 3
Influence of modifications in the long arm on the potency of 2 as inhibitor of [3H]MK-801 binding (10 mM Tris buffer)
30 spermineb
a
Structure
IC50 (mM)
nH
2
0.52 ꢀ 0.32 (46)
1.18 ꢀ 0.19 (43)
15.1 ꢀ 7.1 (24)
16.8 ꢀ 8.2 (3)
H2N
4
NH2
S
20
1.76 ꢀ 0.62 (3)
4.20 ꢀ 2.19 (4)
1.19 ꢀ 0.69 (19)
1.10 ꢀ 0.09 (3)
1.43 ꢀ 0.36 (4)
1.00 ꢀ 0.12 (17)
H2N
H2N
4
4
NH2
NH2
S
S
S
32
16.8 ꢀ 3.6 (4)
51.4 ꢀ 23.7 (8)
O
O
O
35a
H2N
H2N
4
N
H
NH2
S
O
35b
36a
111 ꢀ 61 (6)
5.2 ꢀ 2.2 (4)c
0.95 ꢀ 0.09 (4)
5.48, 12.1 (2)
H
N
4
NH2
N
H
S
O
n.d.
29.0 ꢀ 13.9 (4)
H2N
H2N
4
4
N
NH2
NH2
S
S
H
36b
38a
H
N
282 ꢀ 66 (3)d
n.d.
n.d.
N
H
O
2.21 ꢀ 1.25 (9)
0.96 ꢀ 0.11 (7)
65.4 ꢀ 32.8 (5)
H2N
H2N
4
4
N
H
NH2
NH2
S
S
O
38b
24.7 ꢀ 3.9 (3)
6.81 ꢀ 2.78 (5)
1.25 ꢀ 0.09 (3)
1.34 ꢀ 0.10 (5)
10.3 ꢀ 2.4 (3)
15.0 ꢀ 6.7 (5)
N
H
O
Ph
H2N
H2N
38c
38d
4
4
N
NH2
S
S
H
O
11.7 ꢀ 1.1 (3)
1.37 ꢀ 0.17 (3)
10.1 ꢀ 1.7 (3)
N
H
NH2
Ph
Ph
39
40
16.2, 13.4 (2)
1.56, 2.24 (2)
1.71, 2.44 (2)
O
H2N
H2N
4
N
N
NH2
Ph
S
S
Ph
9.64, 9.62 (2)
1.30, 2.09 (2)
1.66, 2.57 (2)
4
NH2
Ph
a
b
c
d
Hill coefficient.
Attenuation in the presence of 30 mM spermine.
Extracted by computer analysis from biphasic data containing a stimulatory component (EC50 35 mM).
At lower concentrations, stimulation up to 125% was observed (EC50 1.9 mM).
eight-carbon chain resulted in inhibitors at least one order of
magnitude weaker than 2, under our usual assay conditions
(50 mM Tris buffer). Reducing the buffer concentration to
10 mM, however, revealed the considerable potency of 35a,
synthesized originally only as precursor for the triamine 36a.
The amide 35a was almost as potent as the parent compound
(in 10 mM Tris; in 50 mM Tris it was 10 times weaker than 2,
see Fig. 1), and inhibition of [3H]MK-801 binding by 35a was
3e4 times more sensitive to spermine than inhibition by 2 it-
self (Fig. 1). Introduction of a second amide bond resulted in
the diglycyl derivative 35b, lower in potency than 35a by a
factor of 100 and without impressive sensitivity to spermine
(Table 3); 35b served as precursor for the tetraamine 36b.
The polyamines 36a and 36b exhibited mixed properties
(see the footnotes in Table 3), with agonistic stimulation hid-
ing behind inhibition. If the two secondary amino groups in
36b were replaced by oxygens, the resulting diether 32 was
more potent than 36b, but still considerably less potent than
2 (and also less potent than 35a).
The peptidic nature of 35a and 35b opened avenues for
more powerful parallel synthesis procedures for compounds
38aed, 39 and 40. A methyl substituent at position 3 (‘‘a-
position’’) of the propionamide part of 35a was well toler-
ated, with excellent spermine sensitivity (38a), but not in
position 2 (38b). Many amino groups are protected against
oxidation by MAO by methyl substitution in a-position
[25]. Phenyl substitution of 35a was neither tolerated in po-
sition 3 (38c) nor in position 2 (38d), however, some

182
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
O
H2N
NH2
H2N
S
NH2
N
H
S
2
35a
%
%
100
80
60
40
20
0
100
80
60
40
20
0
50mM
TRIS
0
0,1
1
10
100 1000µM
0
0,1
1
10
100 1000µM
%
100
%
100
80
60
40
20
0
80
60
40
20
0
10mM
TRIS
0
0,1
1
10
100 1000µM
0
0,1
1
10
100 1000 µM
Fig. 1. Inhibition of [3H]MK-801 binding by 2 (left) and by its amide analogue 35a (right), in 50 mM (upper row, filled circles: þ100 mM spermine) and in 10 mM
Tris buffer (lower row, grey circles: þ10 mM spermine, filled circles: þ30 mM spermine). Note that spermine and Tris have a stronger influence on inhibition by
35a than on inhibition by 2. Data pooled from at least four experiments.
spermine sensitivity was maintained (factor 10e15) also in
these latter compounds. Exploratory compounds with more
substituents (39 and 40) exhibited moderate potencies with
practically no influence of spermine.
Introduction of an amide bond into the standard polyamine
inverse agonist 1 resulted in 42 (Table 4); spermine sensitivity
of inhibition by 42 was higher than that of inhibition by 1.
Thus, also here a highly spermine-sensitive inhibitor emerged,
however, with relatively poor potency.
demonstrated in our earlier publication [11]. The diguani-
dines 7 and 7iek, however, were all as potent as 2 (Table
5), although their chain length varied considerably. Variable
was only their sensitivity to spermine: only 7i, the shortest
analogue, with the terminal nitrogens at the same
distances from the thieno ring as in 2, exhibited highly
spermine-sensitive inhibition of [3H]MK-801 binding, com-
parable to 2.
5. Discussion
4.4. Diguanidine analogues with various chain lengths
5.1. The terminal amino groups
As the diguanidine arcaine is mentioned in the polyamine
literature at least as often as the diaminoalkanes, we synthe-
sized and evaluated several diguanidine analogues of 2, and
for comparison also 5k, the shorter chain homologue of 2.
The potency of 5k was 10 times lower than that of the
parent compound 2 (Table 5); this critical dependence
of diamine potency on chain length had already been
In this study, we explored the influence of several structural
modifications on the potency of our parent compound 2 as
polyamine-sensitive NMDA receptor blocker. Neither the
modifications at the amino groups, nor the manoeuvres at
the centre of the molecule resulted in any relevant improve-
ment of potency. The relative impact of the various
Table 4
Inhibition of [3H]MK-801 binding (10 mM Tris buffer) by 42, corresponding structurally to 1 with an amide bond interrupting the carbon chain
30 spermineb
a
Structure
IC50 (mM)
nH
1
7.05 ꢀ 2.38 (11)
1.12 ꢀ 0.21 (11)
34.6 ꢀ 5.8 (4)
H2N
H2N
8
NH2
O
42
53 ꢀ 33 (4)
0.88 ꢀ 0.46 (3)
75 ꢀ 64 (4)
8 N
NH2
H
a
Hill coefficient.
Attenuation in the presence of 30 mM spermine.
b

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
183
Table 5
Diguanidine analogues of 2 as inhibitor of [3H]MK-801 binding (10 mM Tris buffer)
Structure IC50 (mM)
30 spermineb
a
nH
5k
2
5.47 ꢀ 1.62 (3)
0.54 ꢀ 0.33 (42)
1.27 ꢀ 0.27 (3)
1.19 ꢀ 0.20 (39)
9.57 ꢀ 2.24 (3)
15.1 ꢀ 7.1 (24)
NH2
NH2
NH2
H2N
2
2
6
S
S
S
H2N
H2N
6
6
H
N
H
N
1.04 ꢀ 0.09 (3)
1.20 ꢀ 0.11 (3)
23.4 ꢀ 7.3 (3)
7i
7j
2
NH
NH
NH
NH
0.74 ꢀ 0.31 (3)
0.31 ꢀ 0.22 (3)
0.77 ꢀ 0.19 (3)
1.65 ꢀ 0.53 (3)
1.22 ꢀ 0.54 (3)
1.76, 1.26 (2)
7.47 ꢀ 3.35 (3)
6.29 ꢀ 2.73 (3)
3.95 ꢀ 1.66 (3)
H2N
2
6
6
NH2
N
H
N
H
S
S
NH
H
N
NH2
7k
7
H2N
N
2
H
NH
NH
H
N
H
N
NH
H2N
2
6
S
NH
a
Hill coefficient.
Attenuation in the presence of 30 mM spermine.
b
modifications, however, may shed some light on the mecha-
nisms of interaction involved. It appears that the primary
amino group at the end of the long octylamine arm was essen-
tial for high potency. For the short aminobutyl arm, a second-
ary amino group was tolerated, but only if integrated into the
carbon chain. Since propyl residues were much less tolerated
than methyl groups, a picture of size-limited targets for the
positively charged amino groups emerges; that allyl and
even benzyl residues were less disturbing than propyl ones
was not necessarily in contradiction to that idea. The p-elec-
trons in these latter substituents might have provided interac-
tion sites for cationic targets [26] at some distance from the
primary target sites, thereby attenuating the negative influence
of size exclusion. The rather limited collection of compounds
of our earlier paper [11] suggested that high potency was cor-
related with high spermine sensitivity. Our new, structurally
more diverse collection does not support such a correlation
(Fig. 2). For example compound 5d, the analogue of 2 with
secondary amino groups, had a 10 times weaker potency
than 2, but similar sensitivity to spermine (Table 1).
To our surprise, the sharp dependence on chain length dem-
onstrated for the potencies of diamine homologues of 2, an ob-
servation that had prompted us to postulate the interaction
with a specific target [11], was not reproduced for the digua-
nidino homologues. They were all practically equipotent to
the diamine 2, but only 7i, corresponding in chain length ex-
actly to 2, exhibited equivalent spermine sensitivity. Thus,
also for the diguanidines absolute potency (IC50) and sensitiv-
ity to spermine (attenuation by 30 mM spermine) differed in
their SARs. Both amino and guanidino groups bear a positive
charge at pH 7.0, however, guanidino groups are more basic
(as e.g. in arginine, pKa 12.5) than amino groups (as e.g. in
lysine, pKa 10.5) [27] and may more successfully compete
for an acidic target site with any arginine residue intrinsic to
the receptor protein.
5.2. The aromatic nucleus
The benzene analogue 24 was nearly equipotent to the
thieno parent compound 2, demonstrating that the orientation
of the alkyl arms attached to the central nucleus was not of
eminent importance. The aromatic nuclei in 2 and 24 might
contribute to improved interaction with the target site either
by their lipophilicity, or by interaction of their p-electrons
with a cationic target [26]. Substitutions increasing the
100
42
38a
35a
1
36a
7i
20
32
2
38c
28
10
38b
38d
11b
11a
5k
5d
37
12
7j
35b
5f
2
24
5g
7k
5b
5a
7
16
5c
5e
40
39
5h
1
0.3
1
10
100
400
IC50 (µM)
Fig. 2. Inhibitory potency of diamines at the NMDA receptor (IC50) is no sig-
nificant predictor of attenuation of inhibition by spermine; filled circles, com-
pounds analysed in 50 mM Tris buffer (attenuation by 100 mM spermine);
open circles, compounds analysed in 10 mM Tris buffer (attenuation by
30 mM spermine); all values are listed in Tables 1e5.

184
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
lipophilicity of the central portion of 2 (as in 5aec, Table 2)
did not increase, but rather decrease potency. But also the al-
kyne 28 e providing p-electrons by a triple bond e was not
more potent than its saturated analogue 37. In both cases, how-
ever, alternative explanations might be given. The substitu-
tions did not only increase lipophilicity, but may also have
been incompatible with tight steric requirements. And the tri-
ple bond in 28 might not only offer p-electrons, but also result
in a change in overall length (slight changes in overall length
can result in huge differences in potency [11], compare 2 with
5k, Table 5). While for a thiophene-interrupted alkyldiamine
chain the optimum position of the p-system was with four
methylenes on one side and eight methylenes on the other
[11], this is not necessarily the case for a triple bond-interrupted
chain. Further studies with additional structural analogues are
needed to clarify these questions.
independent structural lead. The new amide model compound
35a provided inhibition of the NMDA receptor almost as po-
tent as the parent compound 2, with even higher sensitivity to
spermine. The compound was amenable to pharmacokinetic
stabilization by a-methylation (38a) without loss in inhibitory
potency, inviting the in vivo evaluation of this new class of in-
verse polyamine agonists.
7. Experimental protocols
7.1. General chemical procedures
NMR spectra were recorded on a Bruker spectrometer (1H at
200e500, 13C at 50e125 MHz). The chemical shifts are re-
ported in parts per million (d) downfield from tetramethylsilane
(d ¼ 0 ppm). The signal patterns are indicated as s, singlet; bs,
broad singlet; d, doublet; t, triplet; q, quartet; qn, quintet; m,
multiplet. The coupling constants (J ) are given in hertz. Melting
5.3. Modifications in the long arm
The tetraamine 36b (and to some extent also the triamine
36a) exhibited interesting stimulatory (polyamine agonistic)
properties at low micromolar concentrations, in agreement
with well known structural requirements for such a property
(i.e. several positive charges at defined distances from each
other) [3,4]. The weak inhibitory potency of the diether 32 could
have been a consequence not only of reduced lipophilicity, but
also of chain rigidization, extending the critical distance be-
tween the thiophene ring and the terminal amino group. It might
be of interest to test shorter chain homologues. Introduction of
an amide bond led to a new class of compounds with remarkable
properties. Inhibition of [3H]MK-801 binding by 35a exhibited
unprecedented sensitivity to spermine, suggesting that inhibi-
tion of the NMDA receptor by this amide was intimately related
to polyamine regulation. Under low ionic strength conditions,
this new compound was almost as potent as the parent com-
pound 2. Analogous introduction of an amide bond into the
aliphatic diamine 1 returned the highly spermine- and Tris-
sensitive compound 42. The potencies of these amide inhibitors
may depend on target interaction of their uncharged amide moi-
ety, hindered in the presence of excess charged buffer molecules
shielding non-specifically the target site. Exploiting the amena-
bility of amide bond formation, we were able to introduce fur-
ther structural variations by an efficient parallel synthesis
approach. Our demonstration that methyl substitution as in
38a was tolerated without loss in potency offers the prospect
of stabilization against degradation by monoamine oxidase
[25]. It remains to be investigated if also the short butylamine
arm of 35a, and both arms of the parent compound 2 tolerate
such a modification, and whether compounds of this type can
reach their target site in physiological media.
points were determined with a Buchi 530 capillary-tube melt-
¨
ing-point apparatus and are not corrected. TLC’s were per-
formed on silica gel (MerckÔ 60 F-254); reaction products
were visualized by UV fluorescence (254 nm), by exposure to
iodine vapour, or after spraying with 5% ethanolic molybdato
phosphoric acid and subsequent heating. The products were pu-
rified by flash chromatography on silica gel 60 (70e200 mesh
ASTM, 0.063e0.200 mm) purchased by Merck. Products
from solid phase synthesis were obtained in low quantities,
therefore characterization by mass spectroscopy replaced
NMR analysis (electro spray ionization mass spectrometer); ad-
ditionally, they were subjected to purity control by capillary
electrophoresis (CE; in a 100 mM phosphate buffer at
25 ꢁC, voltage 25 kV, 67/60 capillaries). Commercial grade
reagents and solvents were used as supplied with the following
exceptions: DE and THF were freshly distilled from sodium; di-
chlorethane was distilled from phosphorous pentoxide; MeOH
was distilled from magnesium methoxide; PE and DCM were
distilled before use. Abbreviations: AcCN, acetonitrile; AcOEt:
ethyl acetate; AcOH: acetic acid; Boc: tert-butoxycarbonyl; CE:
capillary electrophoresis; DCM: dichlormethane; DE, diethyl
ether; DIC: diisopropylcarbodiimide; DIPEA: diisopropyl-
ethylamine;DME:dimethoxyethane;DMF:dimethylformamide;
DMSO: dimethylsulfoxide; Fmoc-: 9H-fluoren-9-ylmethyloxy-
carbonyl-; HOBt: 1-hydroxybenzotriazol (peptide coupling
reagent); MeOH: methanol; MS, mass spectrometry; PE:
petroleum ether; rt: room temperature; TEA: triethylamine;
TFA: trifluoroacetic acid; THF: tetrahydrofuran; THP:
tetrahydropyranyl.
7.2. Syntheses of N,N-substituted
thiophene-dialkyldiamines
6. Conclusion
Synthesis and evaluation in vitro of various structural ana-
logues of the high potency polyamine inverse agonist 2 re-
sulted in divergent SARs (Fig. 2) for potency and
polyamine-sensitivity, respectively, endorsing the latter as an
7.2.1. Dicarboxylic acid precursors
These precursors were synthesized as described [11]. In the
following, we give the properties of four of them that have not
been described before (Scheme 1).

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
185
7.2.1.1. 8-[5-(3-Carboxy-propyl)-4-methyl-thien-2-yl]-octanoic
acid (3a). Yield: 97% colorless solid, m.p.: 68e69 ꢁC. 1H
NMR (300 MHz; DMSO-d6) d 1.21e1.31 (m, 6H, CH2-(4),
CH2-(5), CH2-(6)), 1.44e1.56 (m, 4H, CH2-(3), CH2-(7)),
1.71 (m, J ¼ 7.4/7.5 Hz, 2H, CH2-(200)), 2.01 (s, 3H, CH3-
(40)), 2.18 (t, J ¼ 7.4 Hz, 2H, CH2-(300)), 2.24 (t, J ¼ 7.3 Hz,
2H, CH2-(2)), 2.58e2.67 (m, 4H, 2HeC(8), 2HeC(100)),
6.48 (s, 1H, H-(30)), 12.05 (bs, 2H, COOH). 13C NMR
(50 MHz; DMSO-d6) d 13.24 (1C, CH3eC(40)), 24.47/31.05
(2C, C(3), C(7)), 26.44 (1C, C(200)), 26.47/29.23 (2C, C(8),
C(100)), 28.33/28.43/28.45 (3C, C(4), C(5), C(6)), 32.80/
33.64 (2C, C(2), C(300)), 127.08 (1C, C(30)), 131.89/134.33/
140.41 (3C, C(20), C(40), C(50)), 174.14/174.48 (2C, COOH).
Analysis: C, H, N for C17H26O4S.
(800)), 2.92 (t, J ¼ 7.3 Hz, 2H, CH2-(3)), 6.57e6.62 (m, 2H,
1H-C(30), 1H-C(40)), 12.06 (s, 2H, COOH). 13C NMR
(50 MHz; DMSO-d6) d 24.45 (C(300)), 24.84 (C(3)), 28.31/
28.41/28.45 (C(400), C(500), C(600)), 29.30 (C(800)), 31.15
(C(700)), 33.61 (C(200)), 35.42 (C(2)), 123.75/124.08 (C(30),
C(40)), 140.66 (C(50)), 142.80 (C(20)), 173.37/174.49 (C(1),
C(10)). Analysis: C, H, N for C15H22O4S.
7.2.2. Substituted diamides from dicarboxylic
acids, method A for gaseous amines
The respective dicarboxylic acid was dissolved under inert
atmosphere in absolute THF. After adding a few drops of ab-
solute pyridine, 1.2 eq. oxalyl chloride were added slowly at rt.
The mixture was stirred at rt for 30 min and then refluxed until
no further gas developed (ca. 1 h). After cooling to 15e20 ꢁC,
the gaseous amine was bubbled in for 30 min, and for another
30 min without cooling. The respective amide was precipitated
by addition of DE, filtered, washed with aqueous bicarbonate
and brine, dried, and purified by normal phase column
chromatography.
7.2.1.2. 8-[5-(3-Carboxy-propyl)-3-methyl-thien-2-yl]-octanoic
1
acid (3b). Yield: 96% yellowish solid, m.p.: 69e70 ꢁC. H
NMR (300 MHz; DMSO-d6) d 1.27 (bs, 6H, CH2-(4), CH2-
(5), CH2-(6)), 1.46e1.51 (m, 4H, CH2-(3), CH2-(7)), 1.76
(m, 2H, CH2-(200)), 2.01 (s, 3H, CH3-(30)), 2.14e2.26 (m,
4H, CH2-(2), CH2-(300), 2.56e2.69 (m, 4H, CH2-(100), CH2-
(8)), 6.49 (s, 1H, H-(40)), 12.01 (bs, 2H, COOH). 13C NMR
(50 MHz; DMSO-d6) d 13.28 (1C, CH3), 24.45/31.00 (2C,
C(3), C(7)), 26.43/27.08 (2C, C(200), C(100)), 28.39/28.45/
28.55 (4C, C(4), C(5), C(6), C(8)), 32.81/33.62 (2C, C(2),
C(300)), 127.31 (1C, C(40)), 131.50 (1C, C(30)), 135.47 (1C,
C(20)), 139.19 (1C, C(50)), 174.10/174.45 (2C, COOH). Anal-
ysis: C, H, N for C17H26O4S.
7.2.2.1. 8-[5-(3-Carbamoyl-propyl)-4-methyl-thien-2-yl]-octa-
noic acid amide (4a). Yield: 67% colorless solid, m.p.:
1
154e156 ꢁC. H NMR (300 MHz; CD3OD-d4) d 1.29e1.39
(m, 6H, CH2-(4), CH2-(5), CH2-(6)), 1.55e1.66 (m, 4H,
CH2-(3), CH2-(7)), 1.85 (m, J1 ¼ 7.4/7.5 Hz, 2H, CH2-(200)),
2.05 (s, 3H, CH3-(40)), 2.15 (t, J ¼ 7.4 Hz, 2H, CH2-(300)),
2.23 (t, J ¼ 7.3 Hz, 2H, CH2-(2)), 2.64e2.71 (m, 4H, CH2-
(8), CH2-(100)), 6.42 (s, 1H, 1H-C(30)). 13C NMR (50 MHz;
DMSO-d6) d 13.39 (s, 1C, CH3eC(40)), 25.19/31.19 (2C,
C(3), C(7)), 26.84 (1C, C(100)), 27.15 (1C, C(200)), 28.48/
28.59/28.71 (3C, C(4), C(5), C(6)), 29.35 (1C, C(8)), 34.38/
35.19 (2C, C(2), C(300)), 127.20 (1C, C(30)), 131.89 (1C,
C(40)), 134.74 (1C, C(20)), 140.43 (1C, C(50)), 174.25/174.74
(2C, 2 ꢂ CONH2). Analysis: C, H, N for C17H28N2O2S.
7.2.1.3. 8-[5-(3-Carboxy-propyl)-3-ethyl-thien-2-yl]-octanoic
1
acid (3c). Yield: 98% yellowish solid, m.p.: 66e68 ꢁC. H
NMR (300 MHz; DMSO-d6) d 1.14 (t, J ¼ 7.6 Hz, 3H,
CH3eCH2-(30)), 1.31e1.39 (m, 6H, CH2-(4), CH2-(5), CH2-
(6)), 1.56e1.67 (m, 4H, CH2-(3), CH2-C(7)), 1.90 (m,
J ¼ 7.4/7.5 Hz, 2H, CH2-(200)), 2.26e2.36 (m, 4H, CH2-(2),
CH2-(300)), 2.47 (q, J ¼ 7.6 Hz, 2H, CH3eCH2-(30)), 2.67 (t,
J ¼ 7.5 Hz, 2H, CH2-(100)), 2.76 (t, J ¼ 7.5 Hz, 2H, CH2-(8)),
6.53 (s, 1H, 1H-(40)). 13C NMR (50 MHz; DMSO-d6)
d 15.81 (1C, CH3eCH2-(30)), 22.34 (1C, CH3eCH2-(30)),
26.04/33.05 (2C, C(3), C(7)), 28.04 (1C, C(200)), 28.46/
30.06/30.15/30.20 (5C, C(4), C(5), C(6), C(8), C(100)), 33.97/
34.92 (2C, C(2), C(300)), 126.86 (1C, C(40)), 136.91/139.93/
141.03 (3C, C(20), C(30), C(50)), 177.21/177.68 (2C,
2 ꢂ COOH). Analysis: C, H, N for C18H28O4S.
7.2.2.2. 8-[5-(3-Carbamoyl-propyl)-3-methyl-thien-2-yl]-octa-
noic acid amide (4b). Yield: 78% colorless solid, m.p.:
144e145 ꢁC. 1H NMR (300 MHz; DMSO-d6) d 1.23 (bs,
6H, CH2-(4), CH2-(5), CH2-(6)), 1.37e1.45 (m, 4H, CH2-
(3), CH2-(7)), 1.71 (m, 2H, CH2-(200)), 1.97e2.07 (m, 7H,
CH2-(2), CH2-(300), CH3-C(30)), 2.53e2.62 (m, 4H, CH2-
(100), CH2-(8)), 6.45 (s, 1H, 1H-C(40)), 6.64/6.70/7.18/7.22 (4
bs, 4H, 2 ꢂ CONH2). 13C NMR (50 MHz; DMSO-d6)
d 13.29 (1C, CH3eC(30)), 25.05/31.03 (2C, C(3), C(7)),
26.96 (1C, C(200)), 27.09 (1C, C(100)), 28.44/28.50/28.62 (3C,
C(4), C(5), C(6)), 28.83 (1C, C(8)), 34.24/35.06 (2C, C(2),
C(300)), 127.20 (1C, C(40)), 131.44 (1C, C(30)), 135.34 (1C,
C(20)), 139.50 (1C, C(50)), 173.81/174.28 (2C, 2 ꢂ CONH2).
Analysis: C, H, N for C17H28N2O2S.
7.2.1.4. 8-[5-(2-Carboxyethyl)-thien-2-yl]-octanoic acid (3k).
This precursor for the synthesis of 5k, a homologue of 2,
was obtained as described [11], with one exception: after Frie-
deleCrafts acylation of 3-(2-thienyl)-propanoic acid methyl-
ester with suberic acid monoethylester chloride, the obtained
ketone was deoxygenated not as the diester, but after hydroly-
sis as the diacid by Et3SiH (as described below for the reduc-
tion of 22 to 23, see Section 7.5.3.2). Yield: 72% white
powder, m.p.: 108 ꢁC. 1H NMR (200 MHz; DMSO-d6)
d 1.26 (s, 6H, CH2-(400), CH2-(500), CH2-(600)), 1.43e1.57 (m,
4H, CH2-(300), CH2-(700)), 2.17 (t, J ¼ 7.2 Hz, 2H, CH2-(200)),
2.48e2.55 (m, 2H, CH2-(2)), 2.67 (t, J ¼ 7.3 Hz, 2H, CH2-
7.2.2.3. 8-[5-(3-Carbamoyl-propyl)-3-ethyl-thien-2-yl]-octa-
noic acid amide (4c). Yield: 59% colorless solid, m.p.:
135e136 ꢁC. 1H NMR (300 MHz; CD3OD-d4) d 1.18 (t,
J ¼ 7.6 Hz, 3H, CH3eCH2-(30)), 1.36e1.46 (m, 6H, CH2-
(4), CH2-(5), CH2-(6)), 1.59e1.70 (m, 4H, CH2-(3), CH2-
(7)), 1.96 (m, J ¼ 7.4/7.5 Hz, 2H, CH2-(200)), 2.21e2.34 (m,

186
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
4H, CH2-(2), CH2-(300)), 2.51 (q, J ¼ 7.6 Hz, 2H, CH3eCH2-
(30)), 2.71 (t, J ¼ 7.5 Hz, 2H, CH2-(100)), 2.79 (t, J ¼ 7.5 Hz,
2H, CH2-(8)), 6.58 (s, 1H, 1H-C(40)). 13C NMR (50 MHz;
CD3OD-d4) d 15.81 (1C, CH3eCH2-(30)), 22.34 (1C, CH3e
CH2-(30)), 26.85/33.07 (2C, C(3), C(7)), 28.46 (1C, C(200)),
28.80/30.09/30.21/30.41 (5C, C(4), C(5), C(6), C(8), C(100)),
35.67/36.50 (2C, C(2), C(300)), 126.81 (1C, C(40)), 136.88/
139.93/141.11 (3C, C(20), C(30), C(50)), 178.70/179.29 (2C,
2 ꢂ CONH2). Analysis: C, H, N for C18H30N2O2S.
in DCM was slowly added. The mixture was boiled until the
reaction was complete. The solvent was evaporated and the
residue dissolved in AcOEt and washed with 1 N HCl and
1 N NaOH. The organic phase was dried, evaporated, and
the residue purified by normal phase chromatography.
7.2.3.1. 8-[5-(3-Propylcarbamoyl-propyl)-thien-2-yl]-octanoic
acid propylamide (4f). Yield: 83% colorless solid, m.p.:
94 ꢁC. 1H NMR (300 MHz; CDCl3-d1) d 0.85 (t, 6H,
2 ꢂ CH3eCH2eCH2eN), 1.26e1.30 (m, 6H, CH2-(4), CH2-
(5), CH2-(6)), 1.34e1.54 (m, 8H, CH2-(3), CH2-(7),
2 ꢂ CH3eCH2eCH2eN), 1.91 (m, 2H, CH2-(200)), 2.04e2.17
(m, 4H, CH2-(2), CH2-(300)), 2.69e2.76 (m, 4H, CH2-(100),
CH2-(8)), 3.09e3.19 (m, 4H, 2 ꢂ CH3eCH2eCH2eN),
6.53e6.61 (m, 2H, 1H-(30), 1H-(40)). 13C NMR (50 MHz;
CDCl3-d1) d 11.31 (2C, 2 ꢂ CH3eCH2eCH2eN), 22.83 (2C,
2 ꢂ CH3eCH2eCH2eN)), 25.69 (1C, C(3)), 27.38 (1C,
C(200)), 28.77/28.96/29.09 (3C, C(4), C(5), C(6)), 29.36/30.00
(2C, C(100), C(8)), 31.47 (1C, C(7)), 35.58/36.77 (2C, C(2),
C(300)), 41.10/41.13 (2C, 2 ꢂ CH3eCH2eCH2eN)), 123.42/
123.88 (2C, C(30), C(40)), 141.65/143.54 (2C, C(20), C(50)),
172.36/172.93 (2C, 2 ꢂ CONHepropyl). Analysis: C, H, N
for C22H38N2O2S.
7.2.2.4. 8-[5-(3-Methylcarbamoyl-propyl)-thien-2-yl]-octanoic
1
acid methylamide (4d). Yield: 87% yellow crystals. H NMR
(300 MHz; CDCl3-d1) d 1.33 (m, 6H, CH2-(4), CH2-(5), CH2-
(6)), 1.62 (m, 4H, CH2-(3), CH2-(7)), 1.97e2.03 (m, 2H,
CH2-(200)), 2.13e2.22 (m, 4H, CH2-(2), CH2-(300)), 2.73 (t,
4H, CH2-(8), CH2-(100)), 2.80 (2s, 6H, 2 ꢂ NeCH3), 5.58 (bs,
2H, 2 ꢂ NH), 6.56 (2d, 2H, 1H-C(30), 1H-C(40)). 13C NMR
(50 MHz; DMSO-d6) d 26.27/32.85 (2C, C(3), C(7)), 26.95
(2C, 2 ꢂ NeCH3), 28.98 (1C, C(200)), 29.91/30.10/30.19/
30.46 (4C, C(4), C(5), C(6), C(100)), 30.95 (1C, C(8)), 36.14/
36.99 (2C, C(2), C(300)), 124.71/125.06 (2C, C(30), C(40)),
142.95/144.57 (2C, C(20), C(50)), 176.28/176.89 (2C,
2 ꢂ CONHCH3). Analysis: C, H, N for C18H30N2O2S.
7.2.2.5. 8-[5-(3-Dimethylcarbamoyl-propyl)-thien-2-yl]-octa-
7.2.3.2. 8-[5-(3-Allylcarbamoyl-propyl)-thien-2-yl]-octanoic
noic acid methylamide (4e). Yield: 83% yellow solid, m.p.:
acid allylamide (4g). Yield: 82% colorless solid, m.p.: 87e
1
1
37e39 ꢁC. H NMR (300 MHz; CDCl3-d1) d 1.33e1.35 (m,
89 ꢁC. H NMR (300 MHz; CDCl3-d1) d 1.33 (bs, 6H, CH2-
6H, CH2-(4), CH2-(5), CH2-(6)), 1.60e1.62 (m, 4H, CH2-(3),
CH2-(7)), 1.96e2.01 (m, 2H, CH2-(200)), 2.27e2.37 (m, 4H,
CH2-(2), CH2-(300)), 2.72 (t, 2H, CH2-(8)), 2.82 (t, 2H, CH2-
(100)), 2.96 (s, 12H, 2Ne(CH3)2), 6.55 (2d, 2H, 1H-C(30), 1H-
C(40)). 13C NMR (50 MHz; CDCl3-d1) d 25.05/26.74/28.86/
29.08/29.30/29.50/30.02/31.54/32.16/33.27/35.27/37.13/
37.20 (14C, C(2), C(3), C(4), C(5), C(6), C(7), C(8), C(300),
C(200), C(100), 4 ꢂ NeCH3), 123.34/123.76 (2C, C(30), C(40)),
141.91/143.47 (2C, C(20), C(50)), 172.53/173.12 (2C,
2 ꢂ CON(CH3)2). Analysis: C, H, N for C20H34N2O2S.
(4), CH2-(5), CH2-(6)), 1.54e1.72 (m, 4H, CH2-(3),
CH2-(7)), 1.95e2.06 (m, 2H, CH2-(200)), 2.14e2.27 (m, 4H,
CH2-(2), CH2-(300)), 2.69e2.84 (m, 4H, CH2-(100), CH2-(8)),
3.84e3.91 (m, 4H, 2 ꢂ H2C]CHeCH2), 5.09e5.22 (m, 4H,
2 ꢂ H2C]CHeCH2), 5.59 (bs, 2H, 2 ꢂ NH), 5.74e5.93 (m,
2H, 2 ꢂ H2C]CHeCH2), 7.53e7.57 (m, 2H, 1H-(30), 1H-
(40)). 13C NMR (50 MHz; CDCl3-d1) d 25.61 (1C, C(3)),
27.31 (1C, C(200)), 28.75/28.94/29.08 (3C, C(4), C(5), C(6)),
29.37/30.00 (2C, C(100), C(8)), 31.46 (1C, C(7)), 35.45/36.62
(2C, C(2), 1C(300)), 41.79/41.83 (2C, 2 ꢂ H2C]CHeCH2),
116.15/116.22 (2C, 2 ꢂ H2C]CHeCH2), 123.44/123.92
(2C, C(30), C(40)), 134.28/134.35 (2C, 2 ꢂ H2C]CHeCH2),
141.58/143.55 (2C, C(20), C(50)), 172.36/172.93 (2C,
2 ꢂ CONHepropyl). Analysis: C, H, N for C22H34N2O2S.
7.2.2.6. 8-[5-(2-Carbamoyl-ethyl)-thien-2-yl]-octanoic acid
amide (4k). Yield: 52% white powder, m.p.: 165e166 ꢁC.
1H NMR (300 MHz; DMSO-d6) d 1.24 (s, 6H, CH2-(400),
CH2-(500), CH2-(600)), 1.39e1.55 (4H, CH2-(300), CH2-(700)),
1.99 (t, J ¼ 7.5 Hz, 2H, CH2-(200)), 2.34 (t, J ¼ 7.2 Hz, 2H,
CH2-(2)), 2.67 (t, J ¼ 7.5 Hz, 2H, CH2-(800), 2.89 (t,
J ¼ 7.5 Hz, 2H, CH2-(3)), 6.56e6.60 (m, 2H, 1H-C(30), 1H-
C(40)), 6.67/6.80/7.21/7.32 (4s, 4H, 2 ꢂ NH2). 13C NMR
(50 MHz; DMSO-d6) d 25.04/25.24 (C(3), C(300)), 28.33/
28.45/28.60 (C(400), C(500), C(600)), 29.31 (C(800)), 31.17
(C(700)), 35.06 (C(200)), 36.67 (C(2)), 123.66/123.83 (C(30),
C(40)), 141.29/142.61 (C(20), C(50)), 172.95/174.33 (C(1),
C(100)). Analysis: C, H, N for C15H24N2O2S.
7.2.3.3. 8-[5-(3-Benzylcarbamoyl-propyl)-thien-2-yl]-octanoic
acid benzylamide (4h). Yield: 74% colorless solid, m.p.:
118e119 ꢁC. 1H NMR (300 MHz; CDCl3-d1) d 1.21e1.32
(m, 6H, CH2-(4), CH2-(5), CH2-(6)), 1.58e1.69 (m, 4H,
CH2-(3), CH2-(7)), 2.02 (m, 2H, CH2-(200)), 2.17e2.29 (m,
4H, CH2-(2), CH2-(300)), 2.73 (t, J ¼ 7.5 Hz, 2H, CH2-(100)),
2.81 (t, J ¼ 7.3 Hz, 2H, CH2-(8)), 4.43 (d, J ¼ 5.7 Hz, 4H,
2 ꢂ CH2ebenzyl), 5.81 (bs, 2H, 2 ꢂ NH), 6.55 (s, 2H, 1H-
C(30), 1H-C(40)), 7.25e7.38 (m, 10H, 2 ꢂ Hebenzyl). 13C
NMR (50 MHz; CDCl3-d1) d 25.62/31.48 (2C, C(3), C(7)),
27.32 (1C, C(200)), 28.77/28.96/29.10/30.03 (5C, C(4), C(5),
C(6), C(8), C(100)), 35.48/36.68 (2C, C(2), C(300)), 43.52 (2C,
2 ꢂ CH2ebenzyl), 123.48/123.99 (2C, C(30), C(40)), 127.44
(2C, 2 ꢂ ( para-arom.)), 127.76/128.65 (8C, 4 ꢂ (ortho-
arom.), 4 ꢂ (meta-arom.)), 138.34/138.41 (2C, 2 ꢂ arom.),
7.2.3. Substituted diamides from dicarboxylic acids,
method B for liquid amines
In absolute DCM, 3 eq. dicarboxylic acid were combined
with 3 eq. Mukaiyama reagent (2-chloro-1-methylpyridinium
iodide) and 6 eq. TEA, and 1 eq. of the liquid amine dissolved

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
187
141.57/143.61 (2C, C(20), C(50)), 172.34/172.91 (2C,
2 ꢂ CONH2). Analysis: C, H, N for C30H38N2O2S.
(2C, C(1), C(400)), 126.91 (1C, C(40)), 136.90/139.98/141.02
(3C, C(20), 1C(30), C(50)). Analysis: C, H,
C18H36N2SCl2$0.4H2O.
N
for
7.2.4. Reduction of diamides to diamines (method C)
Under inert atmosphere, LiAlH4 was dissolved in absolute,
icy THF and the amide was slowly added. The mixture was re-
fluxed until the reactant disappeared (15e30 h). After cooling
to 0 ꢁC, aqueous tartrate was added, the volume reduced by
evaporation, DCM added, and filtered over celite. The residue
was washed with DCM, the combined organic layers washed
with water, dried, and the solvent evaporated. The obtained
raw amine was dissolved in absolute DE, precipitated as the
hydrochloride with gaseous HCl, and further purified by crys-
tallization or by column chromatography.
7.2.4.4. Methyl-{8-[5-(4-methylaminobutyl)-thien-2-yl]-octyl}-
amine dihydrochloride (5d). Yield: 61% colorless solid,
m.p.: 220e230 ꢁC (with decomposition). 1H NMR
(300 MHz; CD3OD-d4) d 1.37 (m, 8H, CH2-(3), CH2-(4),
CH2-(5), CH2-(6)), 1.63e1.75 (m, 8H, CH2-(2), CH2-(7),
CH2-(200), CH2-(300)), 1.68 (s, 6H, 2 ꢂ NeCH3), 2.71e2.82
(m, 4H, CH2-(1), CH2-(400)), 2.98e3.00 (m, 4H, CH2-(8),
CH2-(100)), 6.57 (d, 1H, H-C(30)), 6.61 (d, 1H, H-C(40)). 13C
NMR (50 MHz; CD3OD-d4)
d 25.73/26.20/26.58/28.76/
29.12/29.23/29.68/30.21/32.01/33.40/33.80/44.88 (12C, C(2),
C(3), C(4), C(5), C(6), C(7), C(8), C(100), C(200), C(300),
2 ꢂ NeCH3), 49.13/49.45 (2C, C(1), C(400)), 124.94/125.19
(2C, C(30) C(40)), 142.60/143.93 (2C, C(20) C(50)). Analysis:
C, H, N for C18H36N2SCl2$0.5H2O.
7.2.4.1. 8-[5-(4-Aminobutyl)-4-methyl-thien-2-yl]-octylamine
dihydrochloride (5a). Yield: 60% colorless solid, m.p.:
1
135e140 ꢁC. H NMR (300 MHz; CD3OD-d4) d 1.30e1.40
(m, 8H, CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.56e1.71 (m,
8H, CH2-(2), CH2-(7), CH2-(300), CH2-(200)), 2.64e2.74/
2.87e2.93 (2m, 8H, CH2-(1), CH2-(8), CH2-(400), CH2-(100)),
6.43 (s, 1H, 1H-C(30)). 13C NMR (50 MHz; CD3OD-d4)
d 13.67 (1C, CH3eC(40)), 27.41/28.00/28.09/28.51/29.46/
29.96/30.10/30.19/30.81/32.80 (10C, C(2), C(3), C(4), C(5),
C(6), C(7), C(8), C(100), C(200), C(300)), 40.62/40.75 (2C,
C(1), C(400)), 128.14 (1C, C(30)), 133.44 (1C, C(40)), 135.59
(1C, C(20)), 142.32 (1C, C(50)). Analysis: C, H, N for
C17H34N2SCl2.
7.2.4.5.
{8-[5-(4-Dimethylaminobutyl)-thien-2-yl]-octyl}-di-
methyl-amine dihydrochloride (5e). Yield: 58% colorless
solid, m.p.: 218e219 ꢁC. 1H NMR (300 MHz; CD3OD-d4)
d 1.38 (m, 8H, CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.62e
1.76 (m, 8H, CH2-(2), CH2-(7), CH2-(200), CH2-(300)), 2.72e
2.87 (m, 16H, CH2-(1), CH2-(400), 4 ꢂ NeCH3), 3.08e3.14
(m, 4H, CH2-(8), CH2-(100)), 6.58e6.64 (m, 2H, 1H-C(30),
1H-C(40)). 13C NMR (50 MHz; CD3OD-d4) d 24.95/25.59/
27.40/29.51/29.91/30.07/30.15/30.28/30.93/32.84/43.39 (14C,
C(2), C(3), C(4), C(5), C(6), C(7), C(8), C(100), C(200), C(300),
4 ꢂ NeCH3), 58.69/59.00 (2C, C(1), C(400)), 124.80/125.24
(2C, C(30), C(40)), 142.74/144.66 (2C, C(20), C(50)). Analysis:
C, H, N for C20H40N2SCl2$0.5H2O.
7.2.4.2. 8-[5-(4-Aminobutyl)-3-methyl-thien-2-yl]-octylamine
dihydrochloride (5b). Yield: 68% brown solid, m.p. ꢃ160 ꢁC
1
(decomposition). H NMR (300 MHz; DMSO-d6) d 1.26 (bs,
8H, CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.43e1.58 (m,
8H, CH2-(2), CH2-(7), CH2-(200), CH2-(300)), 2.01 (s, 3H,
CH3eC(30)), 2.56e2.73 (m, 8H, CH2-(1), CH2-(100), CH2-
(400), CH2-(8)), 6.51 (s, 1H, 1H-C(40)), 8.17 (bs, 6H,
2 ꢂ NH3). 13C NMR (50 MHz; DMSO-d6) d 13.33 (s, CH3e
C(30)), 25.85/28.45 (4C, C(3), C(4), C(5), C(6)), 26.3/26.82/
27.96/31.03 (4C, C(2), C(7), C(200), C(300)), 27.10 (1C,
C(100)), 28.77 (1C, C(8)), 38.25/38.38 (2C, C(1), C(400)),
127.32 (1C, C(40)), 131.48 (1C, C(30)), 135.38 (1C, C(20)),
139.37 (1C, C(50)). Molecular weight calculated for
C17H32N2S: 296.52; measured by MS (m/z): 297.3 (M þ H).
7.2.4.6. Propyl-{8-[5-(4-propyllaminobutyl)-thien-2-yl]-octyl}-
amine dihydrochloride (5f). Yield: 72% colorless solid, m.p.
ꢃ240 ꢁC. 1H NMR (300 MHz; CD3OD-d4) d 1.01 (2t,
J1 ¼ 11.2 Hz, J2 ¼ 11.0 Hz, 6H, 2 ꢂ CH3eCH2eCH2eN),
1.36 (bs, 8H, CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.59e
1.79 (m, 12H, CH2-(2), CH2-(200), CH2-(7), CH2-(300),
2 ꢂ CH3eCH2eCH2eN)), 2.69e3.03 (m, 12H, CH2-(1),
CH2-(100), CH2-(8), CH2-(400), 2 ꢂ CH3eCH2eCH2eN),
6.54e6.61 (m, 2H, 1H-C(30), 1H-C(40)). 13C NMR (50 MHz;
CD3OD-d4) d 11.25 (2C, 2 ꢂ CH3eCH2eCH2eN), 20.65
(2C, 2 ꢂ CH3eCH2eCH2eN), 26.56 (1C, C(200)), 27.22/
29.64 (2C, C(2), C(300)), 27.54/29.93/30.10/30.16 (4C, C(3),
C(4), C(5), C(6)), 30.35/30.94 (2C, C(100), C(8)), 32.87 (1C,
C(7)), 48.58/48.67 (2C, C(1), C(400)), 50.49 (2C, 2 ꢂ CH3e
CH2eCH2eN), 124.77/125.21 (2C, C(30), C(40)), 142.83/
144.62 (2C, C(20),C(50)). Analysis: C, H, N for C22H44N2SCl2.
7.2.4.3. 8-[5-(4-Aminobutyl)-3-ethyl-thien-2-yl]-octylamine di-
hydrochloride (5c). Yield: 71% colorless solid, m.p.: not ac-
1
cessible (too hygroscopic). H NMR (300 MHz; CD3OD-d4)
d 1.18 (t, J ¼ 7.6 Hz, 3H, CH3eCH2-(30)), 1.36e1.46 (m,
8H, CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.59e1.80 (m,
8H, CH2-(2), CH2-(7), CH2-(200), CH2-(300)), 2.51 (q,
J ¼ 7.6 Hz, 2H, CH3eCH2-(30)), 2.71 (t, J ¼ 7.4 Hz, 2H,
CH2-(100)), 2.83 (t, J ¼ 6.4 Hz, 2H, CH2-(8)), 2.93e3.00 (m,
4H, CH2-(1), CH2-(400)), 6.61 (s, 1H, 1H-C(40)). 13C NMR
(50 MHz; CD3OD-d4) d 15.82 (1C, CH3eCH2-(30)), 22.32
(1C, CH3eCH2-(30)), 27.43/30.12/30.26 (4C, C(3), C(4),
C(5), C(6)), 27.92/28.46/29.50/33.13 (4C, C(2), C(7), C(200),
C(300)), 28.52 (1C, C(8)), 30.34 (1C, C(100)), 40.57/40.77
7.2.4.7.
Allyl-{8-[5-(4-allylaminobutyl)-thien-2-yl]-octyl}-
amine dihydrochloride (5g). Yield: 76% colorless solid,
1
m.p.: 224e228 ꢁC. H NMR (300 MHz; CD3OD-d4) d 1.36
(m, 8H, CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.59e1.82 (m,
8H, CH2-(2), CH2-(7), CH2-(200), CH2-(300)), 2.68e2.98 (m,
8H, CH2-(1), CH2-(8), CH2-(100), CH2-(400)), 3.62 (2d,
J ¼ 8.4 Hz, 4H, 2 ꢂ H2C]CHeCH2), 5.44e5.57 (m, 4H,

188
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
2 ꢂ H2C]CHeCH2), 5.86e5.97 (m, 2H, 2 ꢂ H2C]CHe
CH2), 6.55e6.60 (m, 2H, 1H-C(30), 1H-C(40)). 13C NMR
(50 MHz; CD3OD-d4) d 26.53 (1C, C(200)), 27.19/29.65 (2C,
C(2), C(300)), 27.53/29.95/30.11/30.17 (4C, C(3), C(4), C(5),
C(6)), 30.35/30.95 (2C, C(100), C(8)), 32.89 (1C, C(7)),
47.96/48.24 (2C, C(1), C(400)), 50.77 (2C, 2 ꢂ H2C]CHe
CH2), 124.11/124.15 (2C, 2 ꢂ H2C]CHeCH2), 124.79/
evaporation, the diguanidine hydrochlorides 7, 7iek were
re-crystallized from MeOH/DE.
7.3.1. tert-Butyl-N-({[8-(5-{4-[2,3-bis(Boc)-guanidino]
butyl}-2-thienyl)octyl]amino}[(Boc)-amino]methylidene)
carbamate (6)
1
Yield: 53% yellowish resin. H NMR (300 MHz; CDCl3-
125.23
(2C,
C(30),
C(40)),
129.24/129.31
(2C,
d1) d 1.27e1.32 (m, 8H, CH2-(3), CH2-(4), CH2-(5), CH2-
(6)), 1.49e1.50 (m, 36H, 4 ꢂ ((CH3)3eO)), 1.55e1.70 (m,
8H, CH2-(200), CH2-(300), CH2-(2), CH2-(7)), 2.70e2.80 (m,
4H, CH2-(100), CH2-(8)), 3.39e3.44 (m, 4H, CH2-(400),
CH2-(1)), 6.56 (s, 2H, 1H-C(30), 1H-C(40)), 8.30 (s, 2H,
NHeC(400), NHeC(1)), 11.50 (s, 2H, 2 ꢂ (CH3)3eOCOe
NH ). 13C NMR (50 MHz; DMSO-d6) d 26.13/27.56/27.72/
28.38/28.49 (7C, C(100), C(200), C(2), C(3), C(4), C(5),
C(6)), 27.95/28.21 (12C, 4 ꢂ (OC(CH3)3)), 28.95 (1C,
C(8)), 29.38 (1C, C(300)), 31.16 (1C, C(7)), 40.18 (2C,
C(400), C(1)), 77.98 (2C, 2 ꢂ NHCOOC(CH3)3), 82.80 (2C,
2 ꢂ C]NCOOC(CH3)3), 123.63/123.83 (2C, C(30), C(40)),
2 ꢂ H2C]CHeCH2), 142.77/144.61 (2C, C(20), C(50)). Anal-
ysis: C, H, N for C22H40N2SCl2$0.25H2O.
7.2.4.8. Benzyl-{8-[5-(4-benzylaminobutyl)-thien-2-yl]-octyl}-
amine dihydrochloride (5h). Yield: 74% colorless solid,
m.p. ꢃ230 ꢁC. 1H NMR (300 MHz; CD3OD-d4) d 1.12e
1.22 (m, 8H, CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.58e
1.77 (m, 8H, CH2-(2), CH2-(7), CH2-(200), CH2-(300)), 2.74
(t, J ¼ 7.3 Hz, 2H, CH2-(8)), 2.82 (t, J ¼ 6.5 Hz, 2H, CH2-
(100)), 2.99e3.08 (m, 4H, CH2-(1), CH2-(400)), 4.20 (d,
J ¼ 3.9 Hz, 4H, 2 ꢂ CH2ebenzyl), 6.55e6.63 (m, 2H, 1H-
C(30), 1H-C(40)), 7.41e7.55 (m, 10H, 2 ꢂ Hebenzyl). 13C
141.99/142.44
(2C,
C(20),
C(50)),
155.18/155.23
152.12
(2C,
(2C,
NMR (50 MHz; CD3OD-d4)
d
26.46/27.10/27.59/29.69/
2 ꢂ NHCOOC(CH3)3),
29.97/30.10/30.17/30.35/30.96/32.89 (10C, C(2), C(3),
C(4), C(5), C(6), C(7), C(8), C(100), C(200), C(300)), 52.38
(2C, 2 ꢂ CH2ebenzyl), 124.79/125.24 (2C, C(30), C(40)),
2 ꢂ C]NCOOC(CH3)3), 163.10 (2C, 2 ꢂ C]NCOOC
(CH3)3). Analysis: C, H, N for C38H66N6O8S.
130.29/130.67/131.01/132.53/132.60
(12C,
2 ꢂ arom.),
7.3.2. tert-Butyl-N-({[6-(5-{2-[2,3-bis(Boc)-guanidino]
ethyl}-2-thienyl)hexyl]amino}[(Boc)-amino]
methylidene)carbamate (6i)
Yield: 9% colorless foam, m.p.: 40e43 ꢁC. 1H NMR
(300 MHz; DMSO-d6) d 1.36e1.38 (m, 4H, CH2-(3), CH2-
142.78/144.66 (2C, C(20), C(50)). Molecular weight calcu-
lated for C30H42N2S: 462.75; measured by MS (m/z):
463.4 (M þ H).
7.2.4.9. 7-[5-(3-Amino-propyl)-thien-2-yl]-octylamine dihydro-
chloride (5k). Yield: 65% brown solid, m.p. ꢃ180 ꢁC. 1H
NMR (300 MHz; DMSO-d6) d 1.25 (s, 8H, CH2-(3), CH2-
(4), CH2-(5), CH2-(6)), 1.52e1.54 (m, 4H, CH2-(2), CH2-
(7)), 1.85 (qn, J ¼ 7.5 Hz, 2H, CH2-(300)), 2.66e2.80 (m, 8H,
CH2-(200), CH2-(400), CH2-(1), CH2-(8)), 6.60e6.64 (m, 2H,
1H-C(30), 1H-C(40)), 7.98e8.09 (m, 6H, 2 ꢂ NH3). 13C
NMR (50 MHz; DMSO-d6) d 25.79/28.28/28.41/28.46 (4C,
C(3), C(4), C(5), C(6)), 26.35/38.04/38.64 (4C, C(200), C(400),
C(1), C(8)), 26.85/31.13 (2C, C(2), C(7)), 28.87 (1C, C(300)),
123.86/124.25 (2C, C(30), C(40)), 140.69/142.84 (2C, C(20),
C(50)). Analysis: C, H, N for C15H30Cl2N2S.
(4)),
1.47e1.70
(m,
40H,
CH2-(2),
CH2-(5),
4 ꢂ (OC(CH3)3)), 2.73 (t, J ¼ 7.5 Hz, 2H, CH2-(6)), 2.99 (t,
J ¼ 6.8 Hz, 2H, CH2-(300)), 3.39 (q, J ¼ 7.0 Hz, 2H, CH2-
(1)), 3.66 (q, J ¼ 6.8 Hz, 2H, CH2-(400)), 6.56/6.63 (2d,
J1 ¼ 3.2 Hz, J2 ¼ 3.2 Hz, 2H, 1H-C(30), 1H-C(40)), 8.29/8.43
(2s, 2H, NHeC(400), NHeC(1)), 11.47e11.49 (m, 2H,
2 ꢂ (CH3)3eOCOeNH ). 13C NMR (50 MHz; DMSO-d6)
d 26.55 (1C, C(3)), 28.01/28.05 (12C, 4 ꢂ (OC(CH3)3)),
28.63 (1C, C(4)), 28.88 (1C, C(2)), 29.71 (1C, C(6)), 29.96
(1C, C(300)), 31.44 (1C, C(5)), 40.88 (1C, C(1)), 42.19 (1C,
C(400)), 79.136/79.21 (2C, 2 ꢂ NHCOOC(CH3)3), 82.96 (2C,
2 ꢂ C]NCOOC(CH3)3), 123.78/124.93 (2C, C(30), C(40)),
138.21 (1C, C(20)), 144.14 (1C, C(50)), 153.09/153.31 (2C,
2 ꢂ NHCOOC(CH3)3), 156.10 (2C, 2 ꢂ C]NCOOC(CH3)3),
163.57/163.64 (2C, 2 ꢂ C]NCOOC(CH3)3). Analysis: C, H,
N for C34H58N6O8S.
7.3. Guanylation of thiophene-dialkyldiamines
The di-Boc-protected pyrazole amidine reagent 1H-pyra-
zole-1-[N,N0-bis(Boc)]carboxamidine was prepared from
1H-pyrazol-1-carboxamidine-HCl with NaH and Boc2O in
THF [13]. The respective diamines 5iek and 2 (Scheme
2) were obtained as described [11] (5i and 5j were only in-
termediates and not isolated; 5k was obtained via 3k and
4k, See Sections 7.2.1.4 and 7.2.2.6) and combined in
AcCN at rt with the di-Boc-protected guanylating reagent.
The mixture was stirred till completion of the reaction
(2e5 h). The solvent was subsequently evaporated, the resi-
due purified by column chromatography, and the products
fully characterized (6, 6iek). The protecting Boc-group
was cleaved off in AcOEt/HClconc (4/1) at rt (30 min). After
7.3.3. tert-Butyl-N-({[7-(5-{3-[2,3-bis(Boc)-guanidino]
propyl}-2-thienyl)heptyl]amino}[(Boc)-amino]methylidene)
carbamate (6j)
Yield: 51% white foam, m.p.: 37e39 ꢁC. 1H NMR
(300 MHz; DMSO-d6) d 1.35 (m, 6H, CH2-(3), CH2-(4),
CH2-(5)), 1.48e1.55 (m, 38H, CH2-(2), 4 ꢂ (OC(CH3)3)),
1.60 (s, 2H, CH2-(6)), 1.92 (q, J ¼ 7.3 Hz, 2H, CH2-(300)),
2.72 (t, J ¼ 7.7 Hz, 2H, CH2-(7)), 2.81 (t, J ¼ 7.6 Hz, 2H,
CH2-(200)), 3.40 (q, J ¼ 7.2 Hz, 2H, CH2-(1)), 3.47 (q,
J ¼ 7.1 Hz, 2H, CH2-(400)), 6.54/6.59 (2d, J1 ¼ 3.3 Hz,
J2 ¼ 3.3 Hz, 2H, 1H-C(30), 1H-C(40)), 8.29/8.36 (2s, 2H,

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
189
NHeC(400), NHeC(1)), 11.50 (s, 2H, 2 ꢂ (CH3)3eOCOe
NH ). 13C NMR (50 MHz; DMSO-d6) d 26.69 (1C, C(3)),
27.34 (1C, C(200)), 28.01/28.25 (12C, 4 ꢂ (OC(CH3)3)),
28.85/28.90 (3C, C(4), C(5), C(7)), 30.01 (1C, C(2)), 30.85
(1C, C(6)), 31.50 (1C, C(300)), 40.04 (1C, C(400)), 40.87 (1C,
C(1)), 79.09/79.13 (2C, 2 ꢂ NHCOOC(CH3)3), 82.89/82.98
(2C, 2 ꢂ C]NCOOC(CH3)3), 123.44/123.90 (2C, C(30),
C(40)), 141.24/143.56 (2C, C(20), C(50)), 153.26 (2C,
2 ꢂ NHCOOC(CH3)3), 156.04/156.13 (2C, 2 ꢂ C]NCOOC
(CH3)3), 163.57/163.60 (2C, 2 ꢂ C]NCOOC(CH3)3). Analy-
sis: C, H, N for C36H62N6O8S.
2.70 (t, J ¼ 7.4 Hz, 2H, CH2-(6)), 2.90 (t, J ¼ 7.1 Hz, 2H,
CH2-(300)), 3.06 (q, J ¼ 6.1 Hz, 2H, CH2-(1)), 3.30e3.33 (m,
2H, CH2-(400)), 6.64/6.72 (2d, J1 ¼ 3.3 Hz, J2 ¼ 3.2 Hz, 2H,
1H-C(30), 1H-C(40)), 7.12e7.60 (m, 8H, 2 ꢂ (NHe
(C]NH )eNH2$HCl)), 7.74e7.81 (m, 2H, 2 ꢂ NHe
(C]NH)eNH2). 13C NMR (50 MHz; DMSO-d6) d 25.66
(1C, C(3)), 27.94 (1C, C(4)), 28.34/28.98/29.20/31.04 (4C,
C(300), C(2), C(5), C(6)), 40.56 (1C, C(1)), 42.01 (1C,
C(400)), 124.00 (1C, C(4)), 125.27 (1C, C(3)), 137.66 (1C,
C(2)), 143.27 (1C, C(5)), 157.04/157.10 (2C, 2 ꢂ NHe
(C]NH)eNH2). Analysis: C, H, N for C14H28Cl2N6S$
0.5H2O. Molecular weight calculated for C14H26N6S:
310.47; measured by MS (m/z): 311.2 (M þ 1).
7.3.4. tert-Butyl-N-({[8-(5-{3-[2,3-bis(Boc)-guanidino]
propyl}-2-thienyl)heptyl]amino}[(Boc)-amino]methylidene)
carbamate (6k)
7.3.7. N-{7-[5-(3-Guanidino-propyl)-thien-2-yl]heptyl}-
guanidine dihydrochloride (7j)
Yield: 89% colorless solid, m.p.: not accessible (too hygro-
Yield: 52% white foam, m.p.: 35e36 ꢁC. 1H NMR
(300 MHz; CDCl3-d1) d 1.32 (s, 8H, CH2-(3), CH2-(4), CH2-
(5), CH2-(6)), 1.49e1.50 (38H, CH2-(2), 4 ꢂ (OC(CH3)3)),
1.58e1.61 (m, 2H, CH2-(7)), 1.93 (q, J ¼ 7.3 Hz, 2H, CH2-
(300)), 2.73 (t, J ¼ 7.6 Hz, 2H, CH2-(8)), 2.82 (t, J ¼ 7.6 Hz,
2H, CH2-(200)), 3.39e3.48 (m, 4H, CH2-(400), CH2-(1)), 6.55/
6.59 (2d, J1 ¼ 3.3 Hz, J2 ¼ 3.3 Hz, 2H, 1H-C(30), 1H-C(40)),
8.32e8.39 (m, 2H, NHeC(400), NHeC(1)), 11.50 (s, 2H,
2 ꢂ (CH3)3eOCOeNH ). 13C NMR (50 MHz; CDCl3-d1)
d 26.77/28.89/28.97/29.11/29.12 (5C, C(2), C(3), C(4), C(5),
1
scopic). H NMR (300 MHz; DMSO-d6) d 1.28 (s, 6H, CH2-
(3), CH2-(4), CH2-(5)), 1.40e1.42 (m, 2H, CH2-(2)), 1.53e
1.55 (m, 2H, CH2-(6)), 1.75 (q, J ¼ 7.4 Hz, 2H, CH2-(200)),
2.66e2.81 (m, 4H, CH2-(100), CH2-(7)), 3.03e3.15 (m, 4H,
CH2-(300), CH2-(1)), 6.60e6.78 (m, 2H, 1H-C(30), 1H-C(40)),
6.85e7.46 (m, 8H, 2 ꢂ NHe(C]NH )eNH2$HCl), 7.77 (t,
J ¼ 5.3 Hz, 1H, NHe(C]NH)eNH2), 7.94 (t, J ¼ 5.2 Hz,
1H, NHe(C]NH)eNH2). 13C NMR (50 MHz; DMSO-d6)
d 25.91/28.24/28.26 (3C, C(3), C(4), C(5)), 26.37/29.29 (2C,
C(100), C(7)), 28.41 (1C, C(2)), 30.49 (1C, C(200)), 31.05
(1C, C(6)), 39.87/40.58 (2C, C(300), C(1)), 123.82/124.10
(2C, C(30), C(40)), 140.97/142.65 (2C, C(20), C(50)), 157.10/
157.19 (2C, 2 ꢂ NHe(C]NH)eNH2). Analysis: C, H, N
for C16H32Cl2N6S$0.5H2O.
C(6)),
27.35
(1C,
C(200)),
28.02/28.26
(12C,
4 ꢂ (OC(CH3)3)), 30.06 (1C, C(8)), 30.85 (1C, C(300)), 31.59
(1C, C(7)), 40.05/40.91 (2C, C(400), C(1)), 79.13/79.17 (2C,
2 ꢂ NHCOOC(CH3)3), 82.91/83.00 (2C, 2 ꢂ C]NCO
OC(CH3)3), 123.41/123.91 (2C, C(30), C(40)), 141.21/143.67
(2C, C(20), C(50)), 153.27 (2C, 2 ꢂ NHCOOC(CH3)3),
156.04/156.14 (2C, 2 ꢂ C]NCOOC(CH3)3), 163.57/163.60
(2C, 2 ꢂ C]NCOOC(CH3)3). Analysis: C, H,
N
for
7.3.8. N-{8-[5-(3-Guanidino-propyl)-thien-2-yl]octyl}-
guanidine dihydrochloride (7k)
C37H64N6O4S.
Yield: 93%, white solid, m.p.: not accessible (too hygro-
scopic). 1H NMR (300 MHz; DMSO-d6) d 1.25 (m, 8H,
CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.39e1.42 (m, 2H,
CH2-(2)), 1.51e1.57 (m, 2H, CH2-(7)), 1.74 (qn, J ¼ 7.6 Hz,
2H, CH2-(200)), 2.64e2.79 (m, 4H, CH2-(100), CH2-(8)),
3.05e3.11 (m, 4H, CH2-(300), CH2-(1)), 6.58e6.63 (m, 2H,
1H-C(30), 1H-C(40)), 7.26 (bs, 8H, 2 ꢂ ((H2N(C]
NH ))$HCl)), 7.83 (t, J ¼ 5.2 Hz, 1H, NHeC(1)), 8.01
(t, J ¼ 5.3 Hz, 1H, NHeC(300)). 13C NMR (50 MHz; DMSO-
d6) d 26.02/28.39/28.46/28.54/28.65 (5C, C(2), C(3), C(4),
C(5), C(6)), 26.41 (1C, C(100)), 29.36 (1C, C(8)), 30.54 (1C,
C(200)), 31.18 (1C, C(7)), 40.64 (2C, C(300), C(1)), 123.86/
124.14 (2C, C(30), C(40)), 141.00/142.73 (2C, C(20), C(50)),
157.08/157.17 (2C, 2 ꢂ NHe(C]NH)eNH2). Analysis: C,
H, N for C17H34Cl2N6S.
7.3.5. N-{8-[5-(4-Guanidino-butyl)-thien-2-yl]octyl}-
guanidine dihydrochloride (7)
Yield: 88% dark yellow solid, m.p.: 105e106 ꢁC. 1H NMR
(200 MHz; DMSO-d6) d 1.25 (m, 8H, CH2-(3), CH2-(4), CH2-
(5), CH2-(6)), 1.43e1.58 (m, 8H, CH2-(200), CH2-(300), CH2-
(2), CH2-(7)), 2.64e2.74 (m, 4H, CH2-(100), CH2-(8)), 3.01e
3.12 (m, 4H, CH2-(400), CH2-(1)), 6.59/6.61 (s, 2H, 1H-C(30),
1H-C(40)), 7.20e7.33 (bs, 8H, 2 ꢂ ((H2N(C]NH ))$HCl)),
7.79e7.88 (m, 2H, NHeC(400), NHeC(1)). 13C NMR
(50 MHz; DMSO-d6) d 25.99/28.38/28.44/28.52/28.62 (5C,
C(2), C(3), C(4), C(5), C(6)), 27.97/28.19 (2C, C(100),
C(200)), 28.92 (1C, C(8)), 29.35 (1C, C(300)), 31.17 (1C,
C(7)), 40.61 (2C, C(400), C(1)), 123.75/123.89 (2C, C(30),
C(40)), 141.84/142.50 (2C, C(20), C(50)), 157.03 (2C,
2 ꢂ C]NCOOC(CH3)3). Analysis: C, H,
N
for
C18H36Cl2N6S.
7.4. The piperidine containing analogues
11a, 11b, and 12
7.3.6. N-{6-[5-(2-Guanidino-ethyl)-thien-2-yl]hexyl}-
guanidine dihydrochloride (7i)
Yield: 91% colorless solid, m.p.: not accessible (too hygro-
scopic). H NMR (300 MHz; DMSO-d6) d 1.30 (s, 4H, CH2-
(3), CH2-(4)), 1.56 (m, 2H, CH2-(2)), 1.65 (m, 2H, CH2-(5)),
Compounds 11a and 11b were prepared from 8a and 8b,
respectively, as described [11], via the protected intermediates
10a and 10b (Scheme 3); for the synthesis of 12, an alternative
route was chosen (described in detail Section 7.4.5). The
1

190
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
starting thiophene alkylamines 8a [28], 8b, and 8c were syn-
thesized from the respective carboxylic acids in two steps
via the amides, as described above (Sections 7.2.2, 7.2.3,
7.2.4); 8b and 8c were used without characterization.
C(1)), 124.89/126.42 (2C, C(30), C(40)), 140.12/145.19 (2C,
C(20), C(50)). Molecular weight calculated for C19H34N2S:
322.56, measured by MS (m/z): 323.4 (M þ 1).
7.4.4. Dimethyl-[8-(5-piperidin-4-ylmethyl-thien-2-yl)-
7.4.1. 4-{5-[8-(Ethoxycarbonyl-methyl-amino)-octyl]-
thieno-2-carbonyl}-piperidine-1-carboxylic acid ethyl
ester (10a)
octyl]-amine dihydrochloride (11b)
1
Yield: 37% colorless solid, m.p.: 196e198 ꢁC. H NMR
(300 MHz; CD3OD-d4) d 1.35e1.95 (m, 17H, CH2-(2), CH2-
(3), CH2-(4), CH2-(5), CH2-(6), CH2-(7), CH2-(300), CH2-
(500), 1H-C(400)), 2.70e3.40 (m, 16H, CH2-(1), CH2-C(400),
CH2-(8), CH2-(200), CH2-(600), 2 ꢂ NeCH3), 6.56e6.61 (m,
2H, 1H-C(300), 1H-C(400)). 13C NMR (50 MHz; CD3OD-d4)
Yield: 27% yellow liquid. 1H NMR (300 MHz; CD3OD-d4)
d 1.22e1.34 (m, 14H, CH2-(3), CH2-(4), CH2-(5), CH2-(6),
2 ꢂ CH3CH2COON), 1.50e1.91 (m, 8H, 2HeC(2), 2He
C(7), 1H-C(300), 1H-C(300), 1H-C(500), 1H-C(500)), 2.86e3.28
(m, 9H, CH2-(1), CH2eC(8), 1H-C(200), 1H-C(600), NeCH3),
3.39e3.51 (m, 1H, 1H-C(400)), 4.09e4.18 (m, 6H, 1H-C(200),
1H-C(600), 2 ꢂ CH3CH2COON), 6.95 (d, J ¼ 3.8 Hz, 1H, 1H-
C(40)), 7.81 (d, J ¼ 3.8 Hz, 1H, 1H-C(30)). 13C NMR
(50 MHz; CDCl3-d1) d 14.65/14.72 (2C, 2 ꢂ CH3CH2COON),
26.55/28.90/29.06 (4C, C(3), C(4), C(5), C(6)), 27.62/27.85
(2C, C(300), C(500)), 28.56/31.26 (2C, C(2), C(7)), 30.63 (1C,
C(1)), 34.25 (1C, NeCH3), 43.25 (2C, C(200), C(600)), 44.57
(1C, C(400)), 61.02/61.30 (2C, 2 ꢂ CH3CH2COON), 125.61
(1C, C(40)), 132.06 (1C, C(30)), 140.58 (1C, C(50)), 155.45
(1C, 1C(20)), 156.12 (1C, NCOOEt)), 156.56 (1C, NCOOEt),
194.42 (1C, C]O). Analysis: C, H, N for C25H40N2O5S.
d
25.61/27.42/29.59/29.94/30.08/30.16/30.93/32.85/37.14/
37.17 (11C, C(2), C(3), C(4), C(5), C(6), C(7), C(8), C(300),
C(400), C(500), CH2eC(400)), 43.40 (2C, 2 ꢂ NeCH3), 45.20
(2C, C(200), C(600)), 59.03 (1C, C(1)), 124.91/126.42 (2C,
C(30), C(40)), 140.14/145.19 (2C, C(20), C(50)). Analysis: C,
H, N for C20H38N2SCl2$0.5H2O.
7.4.5. Synthetic route to the primary amine 12
7.4.5.1. 2,4,6-Trimethyl-N-(8-thien-2-yl-octyl)-benzenesulfona-
mide (9c). The amino group of (8-thien-2-yl-octyl)-amine 8c
(Scheme 3) was sulphonamide-protected under inert atmo-
sphere in absolute DCM. After addition of 1 eq. TEA and
cooling to 0 ꢁC, 1 eq. 2,4,6-trimethylbenzene sulfonyl chloride
dissolved in DCM was slowly (20 min) added and the mixture
stirred overnight at rt without cooling. After washing with
aqueous KHSO4 and drying, the product 9c was purified by
7.4.2. 4-[5-(8-Dimethylamino-octyl)-thieno-2-carbonyl]-
piperidine-1-carboxylic acid ethyl ester (10b)
1
Yield: 67% pale yellow solid, m.p.: 126e128 ꢁC. H NMR
(300 MHz; CDCl3-d1)
d
1.26 (t, J ¼ 7.1 Hz, 3H,
1
CH3CH2COON), 1.29e1.36 (m, 8H, CH2-(3), CH2-(4),
CH2-(5), CH2-(6)), 1.65e1.91 (m, 8H, CH2-(2), CH2-(7),
1H-C(300), 1H-C(300), 1H-C(500), 1H-C(500)), 2.71 (s, 6H,
2 ꢂ NeCH3), 2.80e2.91 (m, 6H, CH2-(1), CH2-(8), 1H-
C(200), 1H-C(600)), 4.09e4.23 (m, 4H, 1H-C(200), 1H-C(600),
CH3CH2COON), 6.82 (d, J ¼ 3.8 Hz, 1H, 1H-C(40)), 7.57
(d, J ¼ 3.8 Hz, 1H, 1H-C(30)). 13C NMR (50 MHz; CDCl3-
d1) d 14.55 (1C, CH3CH2COON), 24.52/26.49/28.47/28.59/
28.75/28.79/30.45/31.02 (9C, C(1), C(2), C(3), C(4), C(5),
C(6), C(7), C(300), C(500)), 42.98/43.15 (4C, C(200), C(600),
2 ꢂ NeCH3), 44.42 (1C, C(400)), 58.05 (1C, C(8)), 61.18
(1C, CH3CH2COON), 125.64 (1C, C(40)), 132.05 (1C,
C(30)), 140.50 (1C, C(50)), 155.33/155.86 (2C, C(20),
NCOOEt), 194.37 (1C, C]O). Analysis: C, H, N for
C23H38N2O3S.
column chromatography. Yield: 56% colorless oil. H NMR
(300 MHz; CDCl3-d1) d 1.18e1.33 (m, 8H, CH2-(3), CH2-
(4), CH2-(5), CH2-(6)), 1.36e1.45 (m, 2H, CH2-(7)), 1.56e
1.63 (m, 2H, CH2-(2)) 2.29 (s, 3H, CH3-para), 2.62 (s, 6H,
2 ꢂ CH3-ortho), 2.76e2.88 (m, 4H, CH2-(1), CH2-(8)), 4.39
(m, 1H, NH)), 6.75 (m, 1H, 1H-C(30)), 6.90 (m, 1H, 1H-
C(40)), 6.94 (s, 2H, 2 ꢂ 1H-Cmeta), 7.09 (m, 1H, 1H-C(50)).
13C NMR (50 MHz; CDCl3-d1) d 20.87 (1C, CH3eCpara),
22.91 (2C, 2 ꢂ CH3eCortho), 26.48/28.86/29.06 (4C, C(3),
C(4), C(5), C(6)), 29.47 (1C, C(7)), 29.82 (1C, C(8)), 31.64
(1C, C(2)), 42.53 (1C, C(1)), 122.70 (1C, C(50)), 123.89
(1C, C(30)). 126.61 (1C, C(40)), 131.90 (2C, 2 ꢂ Cmeta),
133.64/139.03/142.03 (4C, Cipso
145.64 (1C, C(20)). Analysis: C, H, N for C21H31NO2S2.
,
2 ꢂ Cortho
,
2 ꢂ Cmeta),
7.4.5.2.
4-{5-[8-(2,4,6-Trimethyl-benzenesulfonylamino)-
7.4.3. Methyl-[8-(5-piperidin-4-ylmethyl-thien-2-yl)-octyl]-
amine dihydrochloride (11a)
octyl]-thieno-2-carbonyl}-piperidine-1-carboxylic acid ethyl
ester (10c). Compound 9c was (as described in [11]) sub-
jected to FriedeleCrafts acylation by 4-chlorocarbonyl piper-
idine carboxylic acid ethyl ester to yield 58% 10c as a dark
Yield: 33% yellow solid, m.p.: 214e216 ꢁC. 1H NMR
(300 MHz; CD3OD-d4) d 1.35e1.42 (m, 8H, CH2-(3), CH2-
(4), CH2-(5), CH2-(6)), 1.63e1.97 (m, 9H, CH2-(2), CH2-(7),
CH2-(300), CH2-(500), 1H-C(400)), 2.70 (s, 3H, NeCH3), 2.73e
2.79/2.94e3.02 (2m, 8H, CH2-(1), CH2-(8), CH2-(200), CH2-
(600)), 3.39 (m, 2H, CH2eC(400)), 6.61e6.63 (m, 2H, 1H-
C(30), 1H-C(40)). 13C NMR (50 MHz; CD3OD-d4) d 27.14/
27.43/29.60/29.96/30.10/30.15/30.93/32.86/33.59/37.13/37.17
(12C, C(2), C(3), C(4), C(5), C(6), C(7), C(8), C(300), C(400),
C(500), C(700), NeCH3), 45.20 (2C, C(200), C(600)), 50.44 (1C,
1
oil. H NMR (300 MHz; CDCl3-d1) d 1.18e1.29 (m, 11H,
CH2-(3), CH2-(4), CH2-(5), CH2-(6), CH3CH2COON), 1.42
(m, 2H, CH2-(2)), 1.60e1.82 (m, 6H, CH2-(7), 1H-C(300),
1H-C(300), 1H-C(500), 1H-C(500)), 2.28 (s, 3H, CH3-para),
2.62 (s, 6H, 2 ꢂ CH3-ortho), 2.77e2.89 (m, 6H, CH2-(1),
CH2-(8), 1H-C(200), 1H-C(600)), 3.16e3.26 (m, 1H, 1H-
C(400), 4.09e4.25 (m, 4H, 1H-C(200), 1H-C(600),
CH3CH2COON), 5.29 (s, 1H, NH), 6.81 (d, 1H, J ¼ 3.8 Hz,

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
191
1H-C(40)), 6.94 (s, 2H, 2 ꢂ 1H-Cmeta), 7.56 (d, 1H,
7.5. Various aromatic diamines
J ¼ 3.8 Hz, 1H-C(30)). 13C NMR (50 MHz; CDCl3-d1)
d 14.65 (1C, CH3CH2COON), 20.86 (1C, CH3eCpara),
22.89 (2C, 2 ꢂ CH3eCortho), 26.46/28.56/28.79/28.82/28.99/
29.49/30.60/31.20 (9C, C(1), C(2), C(3), C(4), C(5), C(6),
C(7), C(300), C(500)), 42.49 (1C, C(400)), 43.26 (2C, C(200),
C(600)), 44.56 (1C, C(8)), 61.32 (1C, CH3CH2COON),
125.62 (1C, C(40)), 131.88 (2C, 2 ꢂ Cmeta), 132.06 (1C,
C(30)), 133.72 (1C, Cipso), 139.00 (2C, 2 ꢂ Cortho), 140.62
(1C, Cpara), 142.02 (1C, C(50)), 155.47/156.01 (2C, C(20),
CH3CH2COON), 194.43 (1C, C]O). Analysis: C, H, N for
C30H44N2O5S2.
7.5.1. Synthetic route to the benzylamine 16
7.5.1.1. 2-[5-(7-Methoxycarbonyl-heptyl)-thieno-2-carbonyl]-
benzoic acid (14). 8-(2-Thienyl)-octanoic acid methylester
(13, Scheme 4), characterized earlier [11], was FriedeleCrafts
acylated by phthalic acid anhydride as described [11]. Yield:
1
79% colorless solid, m.p.: 91e93 ꢁC. H NMR (300 MHz;
CDCl3-d1) d 1.26e1.40 (m, 6H, CH2-(3), CH2-(4), CH2-(5)),
1.59e1.74 (m, 4H, CH2-(2), CH2-(6)), 2.30 (t, J ¼ 7.5 Hz,
2H, CH2-(7)), 2.86 (t, J ¼ 7.6 Hz, 2H, CH2eC(1)), 3.65 (s,
3H, COOCH3), 6.85 (d, J ¼ 3.5 Hz, 1H, 1H-C(40)), 7.26 (d,
J ¼ 3.5 Hz, 1H, 1H-C(30)), 7.81e7.86 (m, 2H, 1H-C(300),
1H-C(400)), 8.18 (d, J ¼ 8.1 Hz, 1H, 1H-C(200)), 8.51 (d,
J ¼ 7.5 Hz, 1H, 1H-C(500)), 10.42 (s, 1H, COOH). 13C NMR
(50 MHz; DMSO-d6) d 24.33 (1C, C(6)), 28.23/28.37/29.18
(3C, C(3), C(4), C(5)), 30.94/33.17 (3C, C(1), C(2), C(7)),
51.05 (1C, OCOCH3), 125.03/126.05/126.19/127.75/128.23
(5C, C(30), C(40), C(50), C(300), C(600)), 131.68 (1C, C(100)),
133.80/134.31 (2C, C(400), C(500)), 140.94/146.94 (2C, C(20),
C(200)), 158.81/173.25 (3C, C]O, COOH, COOCH3). Analy-
sis: C, H, N for C21H24O5S$0.1H2O.
7.4.5.3. 2,4,6-Trimethyl-N-[8-(5-piperidin-4-ylmethyl-thien-2-
yl)-octyl]-benzenesulfonamide (11c). Compound 10c was sub-
jected to WolffeKishner reduction (as described in [11]) to
1
yield 64% 11c as a pale yellow solid, m.p.: 80e82 ꢁC. H
NMR (300 MHz; CD3OD-d4) d 1.10e1.40 (m, 10H, CH2-
(3), CH2-(4), CH2-(5), CH2-(6), CH2-(7)), 1.45e1.72 (m,
6H, CH2-(2), CH2-(300), CH2-(500)), 2.27 (s, 3H, CH3-para),
2.59 (s, 6H, 2 ꢂ CH3-ortho), 2.52e2.70 (m, 4H, 1H-C(200),
1H-C(600), CH2eC(400)), 2.81 (t, J ¼ 6.9 Hz, 2H, CH2-(8)),
2.96e3.01 (m, 2H, 1H-C(200), 1H-C(600)), 3.28e3.30 (m, 2H,
CH2-(1)), 6.53 (s, 2H, 1H-C(30), 1H-C(40)), 6.99 (s, 2H,
2 ꢂ 1H-Cmeta). 13C NMR (50 MHz; CD3OD-d4) d 20.96 (1C,
1C, CH3eCpara), 23.14 (2C, 2 ꢂ CH3eCortho), 27.50/29.92/
30.15/30.37/30.97/32.82/33.37/39.59 (10C, C(2), C(3), C(4),
C(5), C(6), C(7), C(8), C(300), C(500), CH2eC(400)), 43.14
(1C, C(1)), 46.88 (2C, C(200), C(600)), 124.66/125.84 (2C,
C(30), C(40)), 132.89 (2C, 2 ꢂ Cmeta), 135.89 (1C, Cipso),
140.18 (2C, 2 ꢂ Cortho), 141.37/144.68 (2C, C(20), C(50)),
143.30 (1C, Cpara). Analysis: C, H, N for C27H42N2O2S2.
7.5.1.2. 2-[5-(7-Methoxycarbonyl-heptyl)-thien-2-ylmethyl]-
benzoic acid (15). Compound 14 was subjected to Clemmen-
sen reduction (A in Scheme 4). The amalgam was prepared by
shaking 7.1 eq. Zn powder and 0.14 eq. HgCl2 in aqueous
HCl. After discarding the supernatant, the amalgam was
stirred with 1 eq. of the ketone 14 in toluene/HClconc for
30 min at rt and refluxed for another 3 h. After cooling and di-
lution with 2 N HCl, the aqueous phase was extracted with
AcOEt. After washing with brine and drying, the solvent
was evaporated and the obtained product 15 purified by col-
umn chromatography. Yield: 66% colorless solid, m.p.: 60e
62 ꢁC. 1H NMR (300 MHz; CD3OD-d4) d 1.29e1.34 (m,
6H, CH2-(3), CH2-(4), CH2-(5)), 1.54e1.61 (m, 4H, CH2-
(2), CH2-(6)), 2.28 (t, J ¼ 7.4 Hz, 2H, CH2-(7)), 2.69 (t,
J ¼ 7.5 Hz, 2H, CH2-(1)), 3.63 (s, 3H, COOCH3), 4.48 (s,
2H, CH2eC(600)), 6.52 (m, 2H, 1H-C(30), 1H-C(40)), 7.26e
7.32 (m, 2H, 1H-C(300), 1H-C(400)), 7.41e7.47 (m, 1H, 1H-
C(200)), 7.87 (d, J ¼ 7.3 Hz, 1H, 1H-C(500)). 13C NMR
(50 MHz; CD3OD-d4) d 25.93 (1C, C(6)), 29.84/29.98/30.01
(3C, C(3), C(4), C(5)), 30.93/32.73/34.73/34.89 (4C, C(1),
C(2), C(7), CH2-C(600)), 51.94 (1C, OCH3), 124.50/125.71/
127.49 (3C, C(300), C(30), C(40)), 131.21 (1C, C(100)), 131.86/
132.17/133.08 (3C, C(200), C(400), C(500)), 142.67/143.43/
145.17 (3C, C(20), C(50), C(600)), 170.91/176.01 (2C, COOH,
COOCH3). Analysis: C, H, N for C21H26O4S.
7.4.5.4. 8-(5-Piperidin-4-ylmethyl-thien-2-yl)-octylamine dihy-
drochloride (12). To remove the protecting group from 11c,
6 eq. metallic sodium was added under inert atmosphere at
ꢄ40 ꢁC to 6 eq. naphthalene dissolved in DME. After the so-
lution had turned green (60 min), 1 eq. of the sulphonamide
11c (dissolved in DME) was slowly added (with preservation
of the green color). After stirring without cooling for 2 h, ex-
cess naphthalide was hydrolysed and the mixture distributed
between 2 N NaOH and AcOEt. The organic layer was dried
and evaporated, the residue was precipitated as hydrochloride
and crystallized from MeOH/DE. Yield: 46% colorless solid,
m.p.: 198e201 ꢁC. 1H NMR (300 MHz; CD3OD-d4)
d 1.34e1.44 (m, 10H, CH2-(3), CH2-(4), CH2-(5), CH2-(6),
CH2-(7)), 1.61e1.66 (m, 4H, CH2-(2), 1H-C(300), 1H-C(500)),
1.79e1.89 (m, 3H, 1H-C(300), 1H-C(400) 1H-C(500)), 2.70e
2.76 (m, 4H, CH2eC(400), CH2-(8)), 2.86e3.00 (m, 4H,
CH2-(1), 1H-C(200), 1H-C(600)), 3.33e3.39 (m, 2H, 1H-C(200),
1H-C(600)), 6.57e6.61 (m, 2H, 1H-C(30), 1H-C(40)). 13C
NMR (50 MHz; CD3OD-d4) d 27.40/29.95/30.09/30.15 (4C,
C(3), C(4), C(5), C(6)), 28.51/32.85 (2C, C(2), C(7)), 29.57
(2C, C(300), C(500)), 30.92/37.16 (2C, 1C(8), CH2eC(400)),
37.12 (1C, C(400)), 40.76 (1C, C(1)), 45.18 (2C, C(200),
C(600)), 124.88/126.40 (2C, C(30), C(40)), 140.13/145.18 (2C,
C(20), C(50)). Analysis: C, H, N for C18H34N2SCl2.
7.5.1.3. 8-[5-(2-Aminomethyl-benzyl)-thien-2-yl]-octylamine
dihydrochloride (16). The further steps to 16 were as de-
scribed [11], and the intermediates are not described here.
Yield: 45% (last step) brownish solid, m.p.: 178e182 ꢁC. H
NMR (300 MHz; CD3OD-d4) d 1.34e1.40 (m, 8H, CH2-(3),
CH2-(4), CH2-(5), CH2-(6)), 1.58e1.70 (m, 4H, CH2-(2),
CH2-(7)), 2.75 (t, J ¼ 7.4 Hz, 2H, CH2-(1)), 2.93 (t,
1

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T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
J ¼ 7.4 Hz, 2H, CH2-(8)), 4.18 (s, 2H, CH2-C(100)), 4.24 (s,
2H, CH2-C(600)), 6.54e6.60 (m, 2H, 1H-C(30), 1H-C(40)),
7.35e7.48 (m, 4H, 1H-C(200),1H-C(300), 1H-C(400), 1H-
C(500)). 13C NMR (50 MHz; CD3OD-d4) d 27.39/28.51/
29.93/30.07/30.12/30.93 (6C, C(2), C(3), C(4), C(5), C(6),
C(7)), 32.78 (1C, C(8)), 34.28 (1C, CH2-C(600)), 40.79/41.01
(2C, C(1), CH2eC(100)), 124.90/125.97/128.76/130.33/
130.53/131.80 (6C, C(30), C(40), C(200), C(300), C(400), C(500)),
132.66 (1C, C(100)), 140.56/141.61/145.92 (3C, C(20), C(50),
C(600)). Analysis: C, H, N for C20H32N2SCl2$0.6H2O.
(300 MHz; CDCl3-d1)
d
1.26 (t, J ¼ 7.1 Hz, 3H,
CH3CH2OCO), 1.38e1.40 (m, 4H, CH2-(4), CH2-(5)), 1.63e
1.76 (m, 4H, CH2-(3), CH2-(6)), 1.98 (qn, J ¼ 7.5 Hz, 2H,
CH2-(200)), 2.28e2.37 (m, 4H, CH2-(300), CH2-(2)), 2.71 (t,
J ¼ 7.6 Hz, 2H, CH2-(100)), 2.94 (t, J ¼ 7.3 Hz, 2H, CH2-(7)),
3.68 (s, 3H, CH3OCO), 4.13 (q, J ¼ 7.1 Hz, 2H,
CH3CH2OCO), 7.27 (d, J ¼ 8.1 Hz, 2H, 1H-C(30), 1H-C(50)),
7.89 (d, J ¼ 8.2 Hz, 2H, 1H-C(20), 1H-C(60)). 13C NMR
(50 MHz; CDCl3-d1) d 14.20 (CH3CH2OCO), 24.16/24.77
(2C, C(3), C(6)), 26.04 (1C, C(200)), 28.94 (2C, C(4), C(5)),
33.21/34.24 (2C, C(2), C(7)), 35.02 (1C, C(100)), 38.35 (1C,
C(300)), 51.51 (CH3OCO), 60.13 (CH3CH2OCO), 128.27/
128.63 (4C, C(20), C(30), C(50), C(60)), 135.11 (1C, C(40)),
146.88 (1C, C(10)), 173.62/173.72 (COOCH3, COOCH2CH3),
199.97 (C]O). Analysis: C, H, N for C21H30O5.
7.5.2. The synthetic route to the dithienylmethane
derivative 20
7.5.2.1.
4-{5-[5-(3-Ethoxycarbonyl-propionyl)-thien-2-yl-
methyl]-thien-2-yl}-4-oxo-butyric acid ethyl ester (18). 2,20-
Dithienylmethane (17, Scheme 4 [14]) was FriedeleCrafts
acylated with succinyl chloride monoethylester as described
[11] to yield 32% 18 as a brownish solid, m.p.: 110e
7.5.3.2.
8-[4-(3-Carboxy-propyl)-phenyl]-octanoic
acid
(23). After saponification of 22 in MeOH/H2O (50/1) with
1.5 eq. LiOH, 23 was obtained by deoxygenation, stirring
1 eq. of the free acid (m.p. 118e120 ꢁC) for 15 h at 55e60 ꢁC
with 3 eq. Et3SiH and 5 eq. TFA. After addition of H2O and
acidification with KHSO4, 23 was extracted with AcOEt. After
drying, the solvent was evaporated and the residue purified by
chromatography. Yield: 76%, white solid, m.p.: 121e122 ꢁC.
1H NMR (300 MHz; CD3OD-d4) d 1.28e1.32 (m, 6H, CH2-
(4), CH2-(5), CH2-(6)), 1.54e1.60 (4H, CH2-(3), CH2-(7)),
1.86 (qn, J ¼ 7.5 Hz, 2H, CH2-(200)), 2.23e2.29 (m, 4H, CH2-
(300), CH2-(2)), 2.52e2.61 (m, 4H, CH2-(100), CH2-(8)), 7.07
(s, 4H, arom-H). 13C NMR (50 MHz; CD3OD-d4) d 26.04/
32.68 (2C, C(3), C(7)), 27.96 (1C, C(200)), 30.14/30.22 (3C,
C(4), C(5), C(6)), 34.23/34.92 (2C, C(300), C(2)), 35.68/36.47
(2C, C(100), C(8)), 129.36/129.41 (4C, C(20), C(30), C(50),
C(60)), 140.05/141.50 (2C, C(10), C(40)), 177.44/177.71 (2C,
2 ꢂ COOH). Analysis: C, H, N for C18H24O5.
112 ꢁC. 1H NMR (300 MHz; CDCl3-d1)
d
1.25 (t,
J ¼ 7.1 Hz, 6H, 2 ꢂ CH3CH2OCO), 2.72 (t, J ¼ 6.8 Hz, 4H,
CH2-(2), CH2-(3000)), 3.19 (t, J ¼ 6.8 Hz, 4H, CH2-(3), CH2-
(2000)), 4.14 (q, J ¼ 7.1 Hz, 4H, 2 ꢂ CH3CH2OCO), 4.36 (s,
2H, CH2-(a-thiophene)), 6.92 (d, J ¼ 3.8 Hz, 2H, 1H-C(300),
1H-C(40)), 7.61 (d, J ¼ 3.8 Hz, 2H, 1H-C(3), 1H-C(400)). 13C
NMR (50 MHz; CDCl3-d1) d 14.13 (2C, 2 ꢂ CH3CH2OCO),
28.25 (2C, C(2), C(3000)), 31.28 (1C, CH2-a-thiophene),
33.55 (2C, C(3), C(2000)), 126.95 (2C, C(300), C(40)), 132.16
(2C, C(3), C(400)), 142.70 (2C, C(50), C(200)), 150.47 (2C,
C(20), C(500)), 172.59 (2C, 2 ꢂ COOEt), 190.71 (2C,
2 ꢂ C]O). Analysis: C, H, N for C21H24O6S2.
7.5.2.2. 4-{5-[5-(4-Aminobutyl)-thien-2-ylmethyl]-thien-2-yl}-
butylamine dihydrochloride (20). From 18 we obtained 19
([29], Scheme 4) by WolffeKishner reduction as described
[11]. The steps for the formation of 20 from 19 have been de-
scribed as well [11], and the intermediates are not characterized
here. Yield: 21% (last step) colorless solid, m.p.: not accessible
7.5.3.3. 8-[4-(4-Aminobutyl)-phenyl]-octylamine dihydrochlor-
ide (24). The steps for the formation of diamine 24 from 23
were as described [11], and the intermediates are not charac-
terized here. Yield: 47% (last step) pale greenish powder,
m.p. ꢃ300 ꢁC (decomposition). 1H NMR (300 MHz;
DMSO-d6) d 1.35 (s, 8H, CH2-(3), CH2-(4), CH2-(5), CH2-
(6)), 1.58e1.68 (m, 8H, CH2-(200), CH2-(300), CH2-(2), CH2-
(7)), 2.52e2.65 (m, 4H, CH2-(100), CH2-(8)), 2.87e2.91 (m,
4H, CH2-(400), CH2-(1)), 7.05e7.11 (m, 4H, arom-H). 13C
NMR (50 MHz; CD3OD-d4) d 27.42/30.14/30.18/30.32 (4C,
C(3), C(4), C(5), C(6)), 28.07/28.52/29.32/32.74 (4C, C(200),
C(300), C(2), C(7)), 35.77/36.45 (2C, C(100), C(8)), 40.66/
40.76 (2C, C(400), C(1)), 129.35/129.42 (4C, C(20), C(30),
C(50), C(60)), 140.04/141.52 (2C, C(10), C(40)). Analysis: C,
H, N for C18H34N2Cl2.
1
(too hygroscopic). H NMR (300 MHz; CD3OD-d4) d 1.66e
1.80 (m, 8H, CH2-(2), CH2-(3), CH2-(2000), CH2-(3000)), 2.83/
2.94 (2t, J1 ¼ 6.5 Hz, J2 ¼ 6.7 Hz, 8H, CH2-(1), CH2-(4),
CH2-(1000), CH2-(4000)), 4.20 (s, 2H, CH2-(a-thiophene)), 6.64e
6.70 (m, 4H, 1H-C(30), 1H-C(40), 1H-C(300), 1H-C(400)). 13C
NMR (50 MHz; CD3OD-d4) d 27.89 (2C, C(3), C(2000)), 29.51/
30.39 (4C, C(2), C(4), C(1000), C(3000)), 31.34 (1C, CH2-a-thio-
phene), 40.53 (2C, C(1), C(4000)), 125.24/125.83 (4C, C(30),
C(40), C(300), C(400)), 142.72/144.29 (4C, C(20), C(50), C(200),
1C(500)). Molecular weight calculated for C17H26N2S2:
322.54; measured by MS (m/z): 323.2 (M þ 1).
7.5.3. Synthetic route to 24, the benzene analogue of 2
7.6. The synthetic route to the alkyne diamine 28
7.5.3.1. 8-[4-(3-Methoxycarbonyl-propyl)-phenyl]-8-oxo-octa-
noic acid ethyl ester (22). 4-Phenylbutanoic acid methylester
21 (Scheme 4, commercially available) was FriedeleCrafts
acylated [11] with suberic acid monoethylester chloride to
7.6.1. 2-{[14-Tetrahydro-2H-2-pyranyloxy)-5-tetradecinyl]-
oxy}tetrahydro-2H-pyran (26)
At ꢄ78 ꢁC under inert atmosphere, 1 eq. of n-butyllithium
1
yield 22 (54%) as a white solid, m.p.: 41e42 ꢁC. H NMR
(1.6 M in THF) was added slowly to a solution of 1 eq. of the

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
193
THP-protected 2,5-hexinol 25 [17] in absolute THF. The mix-
ture was allowed to warm to 0 ꢁC and was cooled again to
ꢄ78 ꢁC. The addition of 1 eq. of hexamethyl phosphoric
acid triamide (in absolute THF) was followed slowly
(30 min) by 1 eq. of THP-protected 2,8-bromo-octanol (in ab-
solute THF). The mixture was stirred at rt overnight and
slowly hydrolysed at 0 ꢁC. The organic layer was isolated,
layer was dried and evaporated. The obtained alkyne diamine
28 was dissolved in HCl-saturated MeOH and precipitated as
the hydrochloride by adding DE. The residue was finally vac-
1
uum-dried. Yield: 83% white powder, m.p.: 146e148 ꢁC. H
NMR (200 MHz; DMSO-d6) d 1.27e1.69 (m, 16H, CH2-(2),
CH2-(3), CH2-(8), CH2-(9), CH2-(10), CH2-(11), CH2-(12),
CH2-(13)), 2.11e2.14 (m, 4H, CH2-(4), CH2-(7)), 2.70e
2.77 (m, 4H, CH1-(1), CH2-(14)), 8.18 (s, 6H, 2 ꢂ NH3).
13C NMR (50 MHz; CD3OD-d4) d 18.95/19.35 (2C, C(4),
C(7)), 26.99/27.41 (2C, C(3),C(12)), 27.67/28.46/29.77/
30.08/30.13 (6C, C(2), C(8), C(9), C(10), C(11), C(13)),
40.39/40.74 (2C, C(1), C(14)), 79.87/81.66 (2C, C(5),
C(6)). Analysis: C, H, N for C14H30Cl2N2.
1
dried and evaporated. Yield: 54% colorless liquid. H NMR
(300 MHz; CDCl3-d1) d 1.31e1.74 (m, 28H, CH2-(30), CH2-
(40), CH2-(50), CH2-(2), CH2-(3), CH2-(8), CH2-(9), CH2-
(10), CH2-(11), CH2-(12), CH2-(13), CH2-(300), CH2-(400),
CH2-(500)), 2.10e2.18 (m, 4H, CH2-(4), CH2-(7)), 3.36e
3.39/3.42e3.51/3.71e3.76/3.86e3.89 (4m, 8H, CH2-(60),
CH2-(1), CH2-(14), CH2-(600)), 4.57 (s, 2H, 1H-C(20), 1H-
C(200)). 13C NMR (50 MHz; CDCl3-d1) d 18.58/18.71/19.60/
19.67 (4C, C(40), C(4), C(7), C(400)), 25.48/25.91/26.18/
7.7. The synthetic route to the diether 32
28.79/28.90/29.08/29.34/29.71/30.72/30.76
(12C,
C(30),
7.7.1. 2-(2-Thien-2-yl-ethoxy)-ethanol (30)
C(50), C(2), C(3), C(8), C(9), C(10), C(11), C(12), C(13),
C(300), C(500)), 62.24/62.29 (2C, C(60), C(6)), 67.04 (1C,
C(14)), 67.63 (1C, C(1)), 79.80/80.45 (2C, C(5), C(6)),
98.75/98.81 (2C, C(20), C(200)). Analysis: C, H, N for
C24H42O4.
Under inert atmosphere at 0 ꢁC in dry DMF, 2-(2-thienyl)
ethanol 29 (Scheme 6) [18] was mixed with 1.5 eq. NaH
and stirred for 1.5 h at rt. THP-protected bromo-ethanol
(1.1 eq. in dry DMF) was added slowly, keeping the mixture
at rt. After stirring overnight at 30e40 ꢁC and hydrolysis at
0 ꢁC, solvent was evaporated and the residue purified by col-
umn chromatography. Deprotection in MeOH with a catalytic
amount of toluene-4-sulfonic acid resulted in the alcohol 30.
7.6.2. 1,14-Diazido-tetradec-5-yne (27)
The THP-protected alkynediol 26 was deprotected by stir-
ring in MeOH with a catalytic amount of 0.005 eq. toluene-
4-sulfonic acid at rt. After adding 0.84 eq. K2CO3 and stir-
ring for 1 h at rt, the precipitate was removed by filtration,
the solvent evaporated and the alkynediol purified by column
chromatography. The diol was characterized by NMR analy-
sis (not shown) and converted via the dimesylate to the dia-
zide 27 (Scheme 5): to a solution of 1 eq. of the diol in
absolute DCM, 2 eq. of TEA and 2.2 eq. methane sulfonic
acid chloride were added at 0 ꢁC within 5 min. The mixture
was stirred for 15 min at 0 ꢁC, and overnight at rt. After hy-
drolysis, the organic layer was isolated, dried, and evapo-
rated. The obtained dimesylate was characterized by NMR
analysis (not shown), dissolved in MeOH, and mixed with
2.6 eq. sodium azide (in MeOH). After stirring overnight at
rt, the solvent was evaporated, the residue was dispersed in
water and extracted with DE. The organic layer was dried
and evaporated. Yield (last step): 66% yellow liquid. 1H
NMR (300 MHz; CDCl3-d1) d 1.32e1.71 (m, 14H, CH2-
(2), CH2-(3), CH2-(8), CH2-(9), CH2-(10), CH2-(11), CH2-
(12), CH2-(13)), 2.11e2.22 (m, 4H, CH2-(4), CH2-(7)),
3.23e3.31 (m, 4H, CH2-(1), CH2-(14)). 13C NMR
(50 MHz; CDCl3-d1) d 18.49/18.63 (2C, C(4), C(7)), 26.08
(1C, C(3)), 26.65 (1C, C(12)), 27.91/28.71/28.80/28.97/
29.02 (6C, C(2), C(8), C(9), C(10), C(11), C(13)), 51.02/
51.44 (2C, C(1), C(14)), 79.20/80.92 (2C, C(5), C(6)). Anal-
ysis: C, H, N for C14H24N6.
1
Yield: 70% colorless liquid. H NMR (200 MHz; DMSO-d6)
d 2.30 (t, J ¼ 6.70 Hz, 2H, CH2-(2)), 3.42e3.50 (m, 4H,
CH2-(1), CH2-(20)), 3.60 (t, J ¼ 6.68 Hz, 2H, CH2-(10)), 4.58
(t, J ¼ 5.18 Hz, 1H, OH), 6.87e6.94 (m, 2H, 1H-C(300), 1H-
C(400)), 7.28/7.30 (q, J ¼ 1.28/1.26 Hz, 1H, 1H-C(500)). 13C
NMR (50 MHz; DMSO-d6) d 29.77 (1C, C(2)), 60.18 (1C,
C(1000)), 70.99 (1C, C(10)), 72.05 (1C, C(20)), 123.94 (1C,
C(5 )), 125.25 (1C, C(300)), 126.72 (1C, C(400)), 141.14 (1C,
C(200)). Analysis: C, H, N for C8H12O2S.
7.7.2. [2-(2-Thien-2-yl-ethoxy)-ethoxy]-acetic acid (31)
The alcohol 30 was dissolved in dry THF and added
slowly (1 h) at rt to 7 eq. NaH (dissolved in dry THF) under
inert atmosphere. After stirring for one more hour at rt, 2 eq.
2-bromo-acetic acid (dissolved in dry THF) were added
slowly (4 h) and the mixture refluxed overnight. Excess
NaH was destroyed by addition of water. After evaporation,
the residue was dissolved in water and excess alcohol ex-
tracted with DE. The aqueous layer was acidified with HCl
and extracted with AcOEt. The organic layer was washed,
dried, and evaporated. Yield: 80% colorless liquid. 1H
NMR (200 MHz; DMSO-d6) d 3.01 (t, J ¼ 6.56, 2H, CH2-
(2)), 3.56e3.65 (m, 6H, CH2-(1), eOeCH2eCH2eOe),
4.02 (s, 2H, eOCH2COOH), 6.89e6.95 (m, 2H, 1H-C(40),
1H-C(30)), 7.29/7.32 (q, J ¼ 1.26/1.38 Hz, 1H-C(50)). 13C
NMR (50 MHz; DMSO-d6) d 29.33 (1C, C(2)), 67.19 (1C,
eOeCH2eCH2eO), 69.11 (1C, eOeCH2eCH2eOe),
69.39 (1C, C(1)), 70.57 (1C, eOCH2COOH), 123.57 (1C,
C(50)), 124.87 (1C, C(30)), 126.33 (1C, C(40)), 140.69 (1C,
7.6.3. Tetradec-5-yne-1,14-diamine dihydrochloride (28)
The alkyne diazide 27 was dissolved in AcCN and slowly
dropped into a solution of 3 eq. SnCl2, 12 eq. thiophenol and
9 eq. TEA in AcCN. After stirring for 1 h at rt, 2 N NaOH
was added and the diamine extracted into DCM. The organic
C(20)), 171.26 (COOH). Analysis: C, H,
N
for
C10H14O4S$0.25H2O.

194
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
7.7.3. 4-(5-{2-[2-(2-Amino-ethoxy)-ethoxy]-ethyl}-thien-2-
yl)-butylamine dihydrochloride (32)
7.8.2. 3-Amino-N-{4-[5-(4-aminobutyl)-thien-2-yl]-butyl}-
propionamide dihydrochloride (35a)
The carboxylic acid 31 was further processed to the di-
amine 32. In short, the methylester was FriedeleCrafts acyl-
ated with succinic anhydride [11], the obtained ketone
deoxygenated with Et3SiH as described for the reduction of
22 to 23 (see Section 7.5.3.2), and the final diamine 32 pre-
pared as the dihydrochloride via the dimethylester and the di-
amide [11] (intermediates characterized by NMR analysis, not
shown). Yield: 52% (last step), colorless oil. 1H NMR
(500 MHz; DMSO-d6) d 1.61 (m, 4H, CH2-(3000), CH2-(2000)),
2.67e2.82 (m, 4H, CH2-(4000), CH2-(1000)), 2.91e2.96 (m, 4H,
CH2-(1), eOeCH2eCH2eNH3)), 3.56e3.62 (m, 4H, eOe
CH2eCH2eOe), 3.64e3.74 (m, 4H, CH2-(2), eOeCH2e
CH2eNH3), 6.64/6.68 (d, J1 ¼ 4.45 Hz, J2 ¼ 5.70 Hz, 2H,
1H-C(30), 1H-C(40)), 8.12 (s, 6H, 2 ꢂ NH3). 13C NMR
(125 MHz; DMSO-d6) d 26.38 (1C, C(3000)), 28.00 (1C,
C(4000)), 28.82 (1C, C(1)), 29.94 (1C, C(2000)), 38.40 (2C, e
OeCH2eCH2eNH3, C(1000)), 66.56 (1C, C(2)), 69.35 (1C, e
OeCH2eCH2eO), 69.58 (1C, eOeCH2eCH2eO), 70.97
(1C, eOeCH2eCH2eNH3), 123.97 (1C, C(30)), 124.84
(arom. CH-(40)), 138.66 (1C, C(50)), 142.33 (1C, C(20)). Mo-
lecular weight calculated for C14H26N2O2S: 286.44; measured
by MS (m/z): 287.18 (M þ H).
N-Boc-protected b-alanine was mixed in absolute DCM
with 1.5 eq. 2-chloro-1-methylpyridinium iodide (Mukaiyama
reagent [12]) and 2 eq. TEA. The mono-Boc-protected di-
amine 34a dissolved in DCM was added slowly. The mixture
was refluxed until the reaction was complete. After evapora-
tion, the residue was dissolved in AcOEt and washed twice
with 1 N HCl and 1 N NaOH. After drying, evaporation, and
purification by chromatography, the Boc-groups were removed
in DCM with 20 eq. TFA at rt (ca. 2 h). The solution was
washed with 2 N NaOH, dried, and evaporated. The resulting
diamine 35a was isolated as the hydrochloride from metha-
1
nolic HCl. Yield: 87% colorless solid, m.p.: 253e256 ꢁC. H
NMR (300 MHz; CD3OD-d4) d 1.55/1.74 (m, 8H, CH2e
C(2), CH2-(3), CH2-(200), CH2-(300)), 2.61 (t, J ¼ 6.6 Hz, 2H,
eCOCH2CH2NH3), 2.76e2.83 (m, 4H, CH2-(4), CH2-(100)),
2.94 (m, 2H, CH2-(1)), 3.16e3.24 (m, 4H, CH2-(400), e
COCH2CH2NH3), 6.60e6.63 (m, 2H, 1H-C(30), 1H-C(40)).
13C NMR (50 MHz; DMSO-d6) d 27.87/29.54/29.65/30.35/
30.56/32.85 (7C, eCOCH2CH2NH3, C(2), C(3), C(4), C(200),
C(300), C(400)), 37.42 (1C, C(400)), 40.09/40.56 (2C, C(1),
C(100)), 125.00/125.22 (2C, C(30), C(40)), 143.06/144.08 (2C,
C(20), C(50)), 172.01 (1C, CONH). Analysis: C, H, N for
C15H29N3OSCl2$1.25H2O.
7.8. Peptidic and polyaminic derivatives
7.8.3. N1-{4-[5-(4-Aminobutyl)-thien-2-yl]-butyl}-
The mono-Boc-protected diamines 34a and 34b used as
starting material for the synthesis of 35a and 35b, respectively
(Scheme 7), were prepared via different routes: 34a was de-
rived from 4-[5-(4-aminobutyl)-thien-2-yl]-butylamine [11],
34b in a nine-step process from 2-(2-thienyl)ethanol 29 [18],
that will be outlined only briefly here (Section 7.8.4), since
most reactions have been described elsewhere.
propane-1,3-diamine trihydrochloride (36a)
Under inert atmosphere, 10 eq. LiAlH4 were dissolved in
absolute THF, followed by the amide 35a (in THF). The
mixture was refluxed to the exhaustion of the reactant
(15e30 h), cooled to 0 ꢁC, and hydrolysed by adding aque-
ous tartrate solution. After volume reduction, DCM was
added and precipitate removed by filtration over celite.
The organic layer was washed, dried and evaporated. The
hydrochloride of the triamine 36a was obtained from meth-
anolic HCl and purified by crystallization and/or chromatog-
7.8.1. {4-[5-(4-Aminobutyl)-thiophen-2-yl]-butyl}-carbamic
acid tert-butyl ester (34a)
1
A solution of Boc2O in dioxane was added slowly (20 min)
to a solution of the symmetric diamine 4-[5-(4-aminobutyl)-
thien-2-yl]-butylamine [11] in 2 N NaOH/dioxane. The mix-
ture was stirred overnight at rt, the solvent evaporated, and
the residue distributed between saturated aqueous NaHCO3
and AcOEt. The organic layer was washed with brine and
dried, and the solvent evaporated. The residue was purified
by chromatography. Yield: 23% (for two steps from the di-
raphy. Yield: 59%, colorless solid, m.p. ꢃ230 ꢁC. H NMR
(300 MHz; CD3OD-d4) d 1.69e1.80 (m, 8H, CH2eC(2),
CH2-(3), CH2-(200), CH2-(300)), 2.08e2.19 (m, 2H,
e
e
NHCH2CH2CH2NH2),
2.78e3.22
(m,
12H,
NHCH2CH2CH2NH2, CH2-(1), CH2-(4), CH2-(400), CH2-
(100)), 6.64 (m, 2H, 1H-C(30), 1H-C(40)). 13C NMR
(50 MHz; CD3OD-d4)
30.33 (7C, eNHCH2CH2CH2NH2, C(2), C(3), C(4), C(100),
C(200), C(300)),
37.93/40.55/45.90 (4C,
d
25.28/26.55/27.83/29.53/29.63/
1
amide) yellow solid, m.p.: 74e77 ꢁC. H NMR (300 MHz;
e
CDCl3-d1) d 1.45 (s, 9H, ((CH3)3CO)), 1.48e1.73 (m, 8H,
CH2-(2), CH2-(3), CH2-(200), CH2-(300)), 2.71e2.80 (m, 6H,
CH2-(4), CH2-(100), CH2-(400)), 3.13e3.18 (m, 2H, CH2-(1)),
4.56 (bs, 1H, OCONH ), 6.56 (s, 2H, 1H-C(30), 1H-C(40)).
13C NMR (50 MHz; DMSO-d6) d 28.40 (3C, (CH3)3CO),
28.79/28.91 (2C, C(3), C(300)), 29.46 (1C, C(2)), 29.71/29.90
(2C, C(4), C(400)), 32.74 (1C, C(200)), 40.32 (1C, C(1)),
41.76 (1C, C(100)), 79.10 (1C, (CH3)3CO), 123.57/123.64
(2C, C(30), C(40)), 142.60/142.89 (2C, C(20), C(50)), 155.97
(1C, OCONe). Molecular weight calculated for
C17H30N2O2S: 326.51; measured by MS (m/z): 327.0 (M þ H).
NHCH2CH2CH2NH2, C(1), C(400)), 125.33/125.37 (2C,
C(30), C(40)), 143.35 (2C, C(20), C(50)). Molecular weight
calculated for C15H29N3S: 283.48; measured by MS (m/z):
284.3 (M þ H).
7.8.4. {4-[5-(2-Hydroxyethyl)-thien-2-yl]-butyl}carbamic
acid tert-butyl ester (33)
This intermediate was prepared as the precursor for the
asymmetric, short diamine 34b and was obtained from the
acetic acid ester of 2-(2-thienyl)ethanol 29 (providing
the ethyl arm) and succinic anhydride (providing the butyl

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
195
arm) as described [11]. Deoxygenation of the butyl arm
keto group was achieved with Et3SiH as described for the
reduction of 22 to 23 (see Section 7.5.3.2). The carboxyl
was converted into an amide group (by oxalyl dichloride/
NH3 [11]), and the amide group in turn into an amino group
(by BH3 [30]); the latter was Boc-protected (as described
above in Section 7.8.1) to yield 39% (last two steps) 33
as an oil (solid at <4 ꢁC). 1H NMR (200 MHz; DMSO-
d6) d 1.35e1.57 (m, 13H, BoceCH3, CH2-(2), CH2-(3)),
2.68 (t, J ¼ 6.94 Hz, 2H, CH2-(4)), 2.79e2.95 (m, 4H,
CH2-(1), CH2-(100)), 3.55 (q, J ¼ 6.31 Hz, 2H, eCH2O
(200)), 4.73 (t, J ¼ 5.30 Hz, 1H, eOH), 6.59/6.62 (2d,
J ¼ 3.40/3.40 Hz, 2H, arom. CH-(40), arom. CH-(30)), 6.78
(s, 1H, eNHCO). 13C NMR (50 MHz; DMSO-d6) d 28.26
(BoceCH3), 33.32 (CH2-(100)), 62.03 (eCH2OH (200)),
77.32 (eOCCH3), 123.69 (arom. CH-(30)), 124.52 (arom.
CH-(40)), 138.99 (arom. C(50)), 142.64 (arom. C(20)),
before being added to the mono-Boc-protected diamine 34b
(10% in DMF) and stirred for 2 h at rt. The solvent was evap-
orated and the residue purified by column chromatography.
Deprotection was achieved in TFA containing 5% water (for
no particular reason slightly different from deprotection of
34a described above), to yield the TFA salt 35b quantitatively
1
as a brown oil. H NMR (200 MHz; CD3OD-d4) d 1.40e1.44
(m, 4H, CH2-(200), CH2-(300)), 2.53 (m, 2H, CH2-(100)), 2.64 (m,
4H, CH2-(400), CH2-(2)), 3.13 (t, J ¼ 7.20 Hz, 2H, CH2-(1)),
3.46 (s, 2H, eCOCH2NH3), 3.61 (s, 2H, eCOCH2NHe),
6.35 (m, 2H, 1H-C(30), 1H-C(40)). 13C NMR (50 MHz;
CD3OD-d4) d 27.87 (1C, C(300)), 29.49 (1C, C(400)), 30.31
(1C, C(2)), 30.75 (1C, C(200)), 40.50 (1C, C(400)), 41.53 (1C,
C(1)), 42.22 (1C, eCOCH2NH3), 43.25 (1C, eCOCH2NHe
), 125.49 (1C, C(40)), 126.05 (1C, C(30)), 140.40 (1C, C(20)),
143.90 (1C, C(50)), 167.99/171.19 (2C, 2 ꢂ C]O). Molecular
weight calculated for C14H24N4O2S: 312.44; measured by MS
(m/z): 313.19 (M þ H).
155.58
(eNHCO).
Analysis:
C,
H,
N
for
C15H25NO3S$0.1H2O; Molecular weight calculated 299.44;
measured by MS (m/z): 322.91 (M þ Na), 339.04 (M þ K).
7.8.7. 4-(5-{2-[2-(2-Amino-ethylamino)-ethylamino]-ethyl}-
thien-2-yl)-butylamine tetratrifluoroacetate (36b)
7.8.5. {4-[5-(2-Amino-ethyl)-thiophen-2-yl]-butyl}-
carbamic acid tert-butyl ester (34b)
Compound 36b was obtained from 35b as described above
(Section 7.8.3). For purification, the obtained raw tetraamine
was dissolved in dioxane/2 N NaOH (2/1) and reacted with
6 eq. Boc2O (overnight at rt). After removal of dioxane, the
residue was partitioned between water and AcOEt. The or-
ganic layer was dried and evaporated, and the residue purified
by column chromatography. Deprotection in 95% TFA for 2 h
resulted in the tetraamine 36b. Yield: quantitative as an orange
The OH group of the 2-hydroxyethyl substituent of 33
was transformed into an amino group via eI and eN3
[31] as follows: 2 eq. Ph3P, 2 eq. imidazole, and 2 eq. I2
were dissolved under argon in water-free DCM. After for-
mation of a white precipitate, 33 was slowly added at rt
and stirred overnight. The solvent was evaporated, the ob-
tained iodide purified by column chromatography (yield:
64%) and characterized by NMR (not shown). For conver-
sion to the azide, the iodide was mixed in water-free ace-
tone with 2 eq. NaN3 and refluxed for 48 h. After removal
of the solvent, the residue was distributed between EtOAc
and water. From the dried organic layer the crude azide
was obtained as yellow oil and immediately converted to
the amine by adding 1.65 eq. Ph3P in THF, followed by
2.5 eq. water. After stirring for 50 h at rt, solvents were
evaporated and the residue purified by flash chromatography
(DCM/MeOH/TEA, 30/1/1). Compound 34b was finally ob-
tained as a yellow oil (yield 69%). 1H NMR (200 MHz;
DMSO-d6) d 1.35e1.53 (m, 13H, ((CH3)3CO)), CH2-(2),
CH2-(3)), 2.65e2.75 (m, 4H, CH2-(1), CH2-(4)), 2.85e
2.96 (m, 4H, CH2-(100), CH2-(200)), 6.60 (m, 2H, 1H-C(40),
1H-C(30)), 6.80 (s, 2H, NH2). 13C NMR (50 MHz;
DMSO-d6) d 28.25 (3C, (CH3)3CO)), 28.50 (1C, C(3)),
28.96 (1C, C(4)), 29.03 (2C, C(2), C(100)), 31.18 (1C,
C(1)), 43.52 (1C, C(200)), 77.31 (1C, (CH3)3CO)), 123.82
(1C, C(40)), 124.33 (1C, C(30)), 139.92 (1C, C(50)), 142.59
(1C, C(20)), 155.58 (1C, eOCONe). Molecular weight cal-
culated for C15H24N2O2S: 296.45; measured by MS (m/z):
297.44 (M þ H).
1
oil. H NMR (200 MHz; CD3OD-d4) d 1.57e1.60 (m, 4H,
CH2-(200), CH2-(300)), 2.74e2.86 (m, 6H, CH2-(400), CH2-
(100), CH2-(2)), 3.06e3.33 (m, 10H, CH2-(1),
e
NHCH2CH2NHe, eNHCH2CH2NHþ3 ), 6.65e6.76 (m, 2H,
1H-C(30), 1H-C(40)). 13C NMR (50 MHz; DMSO-d6) d 26.08
(1C, C(300)), 26.47 (1C, C(400)), 27.90 (1C, C(1)), 28.79 (1C,
C(200)), 35.13 (1C, C(100)), 38.54 (1C, eCH2NHþ3 ), 42.63/
42.75 (2C, eNHCH2CH2NHe, eNHCH2CH2NHe), 44.12
(1C, C(2)), 47.81 (1C, eCH2CH2NHþ3 ), 116.43 (eCF3,
J ¼ 292.94 Hz), 124.52 (1C, C(40)), 125.69 (1C, C(30)),
136.03 (1C, C(50)), 143.31 (1C, C(20)), 158.77 (eCOCF3,
J ¼ 33.91 Hz). Molecular weight calculated for C14H28N4S:
284.47; measured by MS (m/z): 285.22 (M þ H).
7.9. Compounds obtained by solid phase synthesis
All solid phase synthesis steps were carried out in cellpor
filter fitted polypropylene syringes and in silylated glass ves-
sels, using 4-[5-(4-aminobutyl)-thien-2-yl]-butylamine [11]
as the first building block. Since the amounts obtained from
solid phase synthesis were insufficient for NMR analysis,
the identity of the end products was verified by CE and by
MS analysis.
7.8.6. 2-Amino-N-({2-[5-(4-aminobutyl)-thien-2-yl]-ethyl-
carbamoyl}-methyl)-acetamide trifluoroacetate (35b)
One equivalent of Boc-protected glycineeglycine was first
stirred for 10 min in DMF with 1 eq. of each HOBt and DIC,
7.9.1. [3-(4-[5-(4-Ammoniobutyl)-2-thienyl]butylamino)-1-
methyl-3-oxopropyl]ammonium ditrifluoroacetate (38a)
4-[5-(4-Aminobutyl)-thien-2-yl]-butylamine (5 eq.) was
coupled in DCM to trityl chloride resin over 14 h. After three

196
T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
washing cycles with DCM/MeOH/DIPEA, Fmoc-protected 3-
amino-3-methylpropionic acid [32] was coupled to the free
amine function (3 h) in a mixture of DIC (3 eq.) and HOBt
(3 eq.) in DMF. After Fmoc-deprotection with a solution of
40% piperidine in DMF over two cycles for 20 min, the resin
was prepared for product release by washing three times with
each of the following solvents: DMF, THF, DCM, MeOH, DE.
Product-splitting in 5% TFA in DCM for 3 h yielded 88% 38a
as a brown oil. Molecular weight calculated for C16H29N3O2S:
311.49; measured by MS (m/z): 312.3 (M þ H).
BH3 in THF (50 eq.) at 50 ꢁC (two cycles over a period of
18 h). Borane complexes were removed by addition of a mix-
ture of 1,8-diazabicyclo[5.4.0]undec-7-en (0.6 mol) in MeOH/
N-methylpyrrolidinone (10/90). Product release as described
for 39. Yield: 65% as a brown oil. Molecular weight calculated
for C29H41N3S: 463.72; measured by MS (m/z): 464.3
(M þ H).
7.10. Diaminododecane (1) with amide insertion
7.10.1. [8-(3-Boc-amino-propionylamino)-octyl]-carbamic
acid tert-butyl ester (41)
7.9.2. [3-(4-[5-(4-Ammoniobutyl)-2-thienyl]butylamino)-2-
methyl-3-oxopropyl]ammonium ditrifluoroacetate (38b)
Same procedure as for 38a. Fmoc-protected 3-amino-2-
methylpropionic acid was used as amino acid component.
Yield: 75% as a brown oil. Molecular weight calculated for
C16H29N3O2S: 311.49; measured by MS (m/z): 312.3 (M þ H).
Mono-Boc-protected 1,8-diaminooctane [21] was coupled
with Boc-protected b-alanine as described for 4feh (7.2.3).
Yield: 71% colorless solid, m.p.: 113e115 ꢁC. 1H NMR
(300 MHz; DMSO-d6) d 1.14e1.21 (m, 8H, CH2-(3), CH2-
(4), CH2-(5), CH2-(6)), 1.21e1.35 (m, 22H, CH2-(2), CH2-
(4),
NHCOCH2CH2NH), 2.83e2.89 (m, 2H, CH2-(1)), 2.95e
3.01 (m, 2H, CH2-(8)), 3.04e3.11 (m, 2H,
4 ꢂ (OC(CH3)3)),
2.17
(t,
J ¼ 7.2 Hz,
2H,
7.9.3. [3-(4-[5-(4-Ammoniobutyl)-2-thienyl]butylamino)-3-
oxo-1-phenylpropyl]ammonium ditrifluoroacetate (38c)
Same procedure as for 38a. Fmoc-protected 3-amino-3-
phenylpropionic acid was used as amino acid component.
Yield: 73% as a brown oil. Molecular weight calculated for
C21H31N3OS: 373.56; measured by MS (m/z): 374.3 (M þ H).
NHCOCH2CH2NH), 6.69e6.73 (m, 1H, NHCOCH2CH2NH ),
7.76 (s, 1H, NHCOCH2CH2NH). 13C NMR (50 MHz; DMSO-
d6)
d
26.20/26.30 (2C, C(3), C(6)), 28.19 (6C,
2 ꢂ (OC(CH3)3)), 28.64/28.68 (2C, C(4), C(5)), 29.02/29.43
(2C, C(2), C(7)), 35.72 (1C, NHCOCH2CH2NH), 36.75 (1C,
NHCOCH2CH2NH), 38.35 (1C, C(8)), 39.77 (1C, C(1)),
77.21/77.48 (2C, 2 ꢂ NHCOOC(CH3)3), 155.39/155.52 (2C,
(CH3)3OCONHC(1), NHCOCH2CH2NHCO), 170.00 (1C,
NHCOCH2CH2NH). Analysis: C, H, N for C21H41N3O5.
7.9.4. [3-(4-[5-(4-Ammoniobutyl)-2-thienyl]butylamino)-3-
oxo-2-phenylpropyl]ammonium ditrifluoroacetate (38d)
Same procedure as for 38a. Fmoc-protected 3-amino-2-
phenylpropionic acid [33] was used as amino acid component.
Yield: 78% as a brown oil. Molecular weight calculated for
C21H31N3OS: 373.56; measured by MS (m/z): 374.3 (M þ H).
7.10.2. 8-(3-Ammonium-propionylamino)-octyl-ammonium
dichloride (42)
7.9.5. (1S )-3-[4-[5-(4-Ammoniobutyl)-2-thienyl]butyl(ben-
zyl)amino]-1-benzyl-3-oxopropylammonium ditrifluoroace-
tate (39)
Compound 41 was deprotected as described for the synthe-
sis of 35a (7.8.2). Yield: (99%) white powder, m.p.: 218e
219 ꢁC. 1H NMR (300 MHz; DMSO-d6) d 1.24e1.28 (m,
8H, CH2-(3), CH2-(4), CH2-(5), CH2-(6)), 1.35e1.38 (m,2H,
CH2-(7)), 1.49e1.54 (m, 2H, CH2-(2)), 2.46 (t, J ¼ 7.1 Hz,
2H, NHCOCH2CH2NH3), 2.71 (t, J ¼ 7.5 Hz, 2H, CH2-(1)),
2.92 (t, J ¼ 7.5 Hz, 2H, NHCOCH2CH2NH3), 2.98e3.05 (m,
2H, CH2-(8)), 8.01 (s, 6H, 2 ꢂ NH3), 8.12e8.16 (m, 1H,
NH). 13C NMR (50 MHz; DMSO-d6) d 25.79/26.25/26.79
(3C, C(4), C(5), C(6)), 28.43/28.87 (3C, C(2), C(3), C(7)),
4-[5-(4-Aminobutyl)-thien-2-yl]-butylamine [15] (5 eq.)
was coupled in DMF to 4-nitrophenylcarbonate-activated
WangÒ resin over 12 h. After three washing cycles with
DMF/DCM/DMF, reductive amination [34] was achieved by
addition of benzaldehyde (3 eq.) and NaCNBH3 in DMF/
AcOH (99/1) over two cycles (2 ꢂ 18 h) at 25 ꢁC. After
repeated washing cycles (DMF, THF, DCM and DMF),
Fmoc-protected (S )-3-amino-4-phenylbutyric acid was cou-
pled for 3 h in a solution of DIC (3 eq.), HOBt (3 eq.) and
DIPEA (10 eq.) in DMF. After Fmoc-deprotection in 40%
piperidine in DMF (2 ꢂ 20 min), the resin was prepared for
product release by washing three times with each of the
following solvents: DMF, THF, DCM, MeOH, DE. Product-
splitting in TFA/DCM (1/1) for 3 h yielded 42% 39 as a brown
oil. Molecular weight calculated for C29H39N3OS: 477.71;
measured by MS (m/z): 478.2 (M þ H).
31.77
(1C,
NHCOCH2CH2NH3),
35.04
(1C,
NHCOCH2CH2NH3), 38.24/38.42 (2C, C(1), C(8)), 169.10
(1C, CO). Analysis: C, H, N for C11H27N3OCl2$0.25H2O.
7.11. Pharmacological evaluation
Specific binding of [3H]MK-801 (17e25 Ci/mmol, ART-
661, ARC Inc., St. Louis USA; NET-972, Perkin Elmer Life
Sciences Inc., Boston, USA) to rat brain membranes (prepared
from hippocampus or from cerebral cortex) was performed as
described [5,11]. Against widespread habits (non-equilibrium
conditions, i.e. incubation time 1 h or shorter, some authors
even prefer the nominal absence of glutamate and glycine),
we prefer conditions close to equilibrium (2 h incubation
7.9.6.
(1S )-3-[4-[5-(4-Ammoniobutyl)-2-thienyl]butyl
(benzyl)amino]-1-benzylpropylammonium ditrifluoroacetate
(40)
Procedure as described for 39. One step before product re-
lease, the amide function was reduced [30] by addition of 1 M

T. Po¨hler et al. / European Journal of Medicinal Chemistry 42 (2007) 175e197
197
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tamate and glycine). Nonspecific binding was defined by bind-
ing of [3H]MK-801 to closed channels, i.e. without addition of
the channel opening co-agonists glutamic acid and glycine, but
with addition of their respective antagonists D-APV (10 mM)
and 5,7-DCKA (1 mM; both from TocriseCookson). When it
turned out that inhibition of [3H]MK-801 binding by some
of our test compounds was extremely sensitive to Tris buffer
concentration, we switched from 50 to 10 mM Tris; to main-
tain equilibrium conditions, incubation time was increased
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nH
the inhibition data to the function B ¼ B0 ꢂ IC50
/
(xnH þ IC50nH) þ NB, where B was the amount of radioligand
bound at various concentrations x of the (inhibitory) test com-
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Parts of this study have been financially supported by
Merck KGaA, Darmstadt, Germany. We sincerely acknowl-
edge the technical support by the following colleagues: E.
Roos and S. Bihler (NMR spectra), I. Prieß, I. Brill and B.
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