Cinnamic amides of (S)-2-(aminomethyl)pyrrolidines are potent H3 antagonists

Article abstract of DOI:10.1016/j.bmc.2004.03.021

New imidazole-free H₃ antagonists have been found in a series of cinnamic amides of (S)-(aminomethyl)pyrrolidines. The influence of the substituent on the aromatic moiety on the potency and the inhibition of three cytochrome P450 subtypes are also described.

Full text of DOI:10.1016/j.bmc.2004.03.021

Bioorganic & Medicinal Chemistry 12 (2004) 2603–2616
Cinnamic amides of (S)-2-(aminomethyl)pyrrolidines are potent
H3 antagonists
Bernd Peschke,a,* Sonja Bak,a Rolf Hohlweg,b Ingrid Pettersson,c
Hanne Hoffmann Frølund Refsgaard,d Dorthe Viuff e and Karin Rimvalle
aProtein and Peptide Chemistry, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Mꢀaløv, Denmark
bMedChem Research II, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Mꢀaløv, Denmark
cProtein Structure, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Mꢀaløv, Denmark
dDrug Metabolism, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Mꢀaløv, Denmark
eMolecular Pharmacology, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Mꢀaløv, Denmark
Received 21 January 2004; accepted 10 March 2004
Available online 2 April 2004
Abstract—New imidazole-free H3 antagonists have been found in a series of cinnamic amides of (S)-(aminomethyl)pyrrolidines. The
influence of the substituent on the aromatic moiety on the potency and the inhibition of three cytochrome P450 subtypes are also
described.
ꢀ 2004 Elsevier Ltd. All rights reserved.
1. Introduction
peramide,10 GT-2331,11 FUB 470,12 or ciproxifan13
contained an imidazole-moiety. Only very recently, a
number of new, imidazole-free H3 antagonists have been
reported,14–24 some of them showing oral in vivo potency
and favorable pharmacokinetic properties. Similarly to
the reported observations in the literature, we found
that imidazole-free H3 antagonists were superior lead
compounds for an orally available drug candidate,25
compared to our previously prepared imidazole-con-
taining H3 antagonists.
Histamine plays an important role in a variety of bio-
logical processes1;2 ranging from effects as a neuro-
transmitter in the central nervous system (CNS) to
peripheral effects on, for example inflammatory condi-
tions, gastric acid secretion and smooth muscle con-
traction. Due to its importance selective ligands have
been developed for H1, H2 and H3 receptors,3 and also
for the H4 receptor,4;5 that was recently discovered.2
The H3 receptor is a presynaptic histamine receptor,
which was first characterized in rats by Arrang et al.6 in
1983. The human H3 receptor was cloned in 1999 by
Lovenberg et al.7 Information in the literature8 suggests
that a functional antagonist of the H3 receptor could
lead to therapeutics in connection with for example,
attention-deficit hyperactivity disorder, epilepsy, obes-
ity, or Alzheimer’s disease. Therefore we were interested
in identifying functional H3 receptor antagonists that
are active in the CNS after oral administration.
The successful discovery of monoamides of piperazine25
as selective and potent H3 antagonists, inspired us to
explore the possibility of including diversity in the amine
part. Since the lead compounds had shown, that the
constrained piperazine was highly suited, when search-
ing for H3 antagonists, we wanted to apply other, dif-
ferently constrained diamines, rather than open-chain
diamines. As a consequence of the changed topography
of these amines, we expected that a change in the
topography in the acid part would be necessary in order
to obtain new types of H3 antagonists.
Since its discovery selective ligands for the H3 receptor
have been found.9 All the early ligands, such as thio-
2. Results and discussion
Keywords: H3 antagonist; Cinnamic amides; Diamine; Cytochrome P450.
* Corresponding author. Tel.: +45-44-434719; fax: +45-44-663450;
e-mail: bpes@novonordisk.com
Two different strategies for the synthesis of the amine part
were employed. In the first approach BOC-protected
0968-0896/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2004.03.021

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B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
amino alcohols I were oxidized by Swern oxidation to
the corresponding aldehydes II. Reductive amination
with a secondary amine, followed by deprotection fur-
nished diamines III, which were used for coupling with
selected cinnamic acids. However, when starting from
enantiomerically pure amino alcohol derivatives, this
route yielded partially racemized diamines, with enan-
tiomeric excesses of about 90% ee. Therefore, another
reaction sequence was used in these examples. After
forming amides V from BOC-protected amino acids IV
with the corresponding amines by reaction with 1-(3-
dimethylaminopropyl)-3-ethylcarbodiimide hydrochlo-
and the ketone employed were commercially available
or known.35 Acid 636 was prepared analogously from
malonic acid (4), utilizing aldehyde 5 (Scheme 2).
A different strategy, shown in Scheme 3, was chosen for
the synthesis of the cyclopropylcarbonyl-substituted
cinnamic acid 8. Starting from commercially available
bromide 7, a Heck-reaction was performed,37 yielding a
cinnamic ester, which, upon saponification with lithium
hydroxide furnished cinnamic acid 8.
The coupling of amines III and cinnamic acids VI were
performed in all cases utilizing EDAC and DHOBt as
ride
(EDAC)
and
3-hydroxybenzotriazin-4-one
(DHOBt), and removal of the BOC group, the final
reduction with lithium aluminum hydride gave rise to
the diamines III without detectable racemization.26–30
Using either of these reaction sequences, diamines 1, 2,
and 3 were obtained (Scheme 1).
O
Br
a)
HO
39%
O
O
Most of the cinnamic acids were either purchased or
were prepared from the corresponding aldehydes or
ketones by Knoevenagel reaction with malonic acid
according to the literature procedures.31–34 All aldehydes
8
7
Scheme 3. (a) (i) Pd(PPh3)4, CH2@CHCOOEt, NEt3; (ii) LiOH,
dioxane/water.
H
O
OH
( )m
N
( )m
N
a)
( )n
( )n
b)
R1'
BOC
II
BOC
N
I
R1
( )m
m = 1, 2
( )n
n = 0, 1, 2
N
H
R1'
O
O
d)
OH
N
III
R1
( )m
( )m
c)
( )n
( )n
N
N
BOC
BOC
V
IV
N
N
N
N
H
N
H
N
H
2
3
1
Scheme 1. (a) DMSO, (COCl)2, Et3N; (b) (i) HNR1 R10, NaBH(OAc)3, HOAc (ii) TFA; (c) EDAC, DHOBt, Et3N; (d) (i) TFA, (ii) LiAlH4.
H
N
O
O
O
O
a)
HO
+
HO
OH
N
76%
N
N
N
N
4
5
6
Scheme 2. (a) Pyridine, piperidine.

B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
2605
coupling reagent in the presence of an amine base, typi-
cally triethylamine, yielding cinnamic amides VII as de-
picted in Scheme 4. In cases where none racemic chiral
amines had been used, enantiomerical excesses of 90–99%
ee have been found in the experiments, where it was
N
NH
1
determined by capillary electrophoreses. The H NMR
9
characterization of the compounds VII, proved in most
cases to be difficult, because unsymmetrically N,N-
disubstituted amides resulted in two sets of signals,
reflecting the two possible rotamers, which are separable
on the NMR time scale. In summary, the syntheses of all
test compounds 10–41 were accomplished in few steps,
beginning with readily available starting materials. This
easy access resulted in a high number of prepared amides.
Figure 1.
activity at the human H3 receptor, as one might expect
from a very different distance between the amide moiety
and the free amino group, it is surprising, that com-
pound 25 exhibits high antagonist potency in the
[35S]GTPc[S] binding assay.
Starting with the commercially available (S)-2-((pyr-
rolidin-1-yl)methyl)pyrrolidine (9) as a first example for
a possible amine, we prepared compounds 10–13 by
acylation with the respective acids. We chose only a
limited number of acids, which we considered to be a
suitable test set, in order to elucidate whether amides of
amine 9 could give compounds with similar biological
activity to our lead compounds from the piperazine
series.25 We were delighted to see, that amides, derived
from cinnamic acids, namely amides 11 and 13, showed
potencies at the human H3 receptor of 10 and 11 nM,
respectively, in the [35S]GTPc[S] binding assay.38 As a
consequence of these positive results a further investi-
gation based on the above amides was initiated (Fig. 1).
Our next approach was to investigate the influence of
the substitution pattern of the aromatic moiety on the
activity as H3-ligands of the final amides. The results of
which indicated that substitution with bromine is
allowed in all positions. The regioisomeric compounds
11, 27, and 28 all show very similar activities at the hH3
receptor. A combination of two halogen-substitutions,
for example, in the 2-fluoro-4-bromocinnamic amide 41,
resulted in highly potent H3 antagonists. A similar
broad tolerance was found for the position of substitu-
tion, when investigating other types of substituents:
both electron withdrawing substituents like cyano––as
shown in amide 30––or alkanoyl––as in the cycloprop-
ylketone 31, as well as electron-donating substituents
like methoxy groups––as demonstrated with amide 32––
could be found in very potent antagonists. Especially the
potency of dimethoxy-substituted derivatives as in
amides 29 or 33 suggest, that electron-rich cinnamic
amides are well accepted by the hH3 receptor. It should
be noted, however, that amide 33 was chemically
unstable in acidic solutions, forming the inactive Z-
double bond isomer, and hence making this compound
useless as a drug candidate. The screening did not
indicate any activity as H3 antagonist for the Z-isomer.
With respect to this isomerization the stabilities of
compounds 14, 17, and 18 have been investigated,
showing no sign of rearrangement. For all other com-
pounds no isomerization was observed either.
Initially, we investigated the influence of a variation in
the amine moiety on the biological potency of cinnamic
amides 14–26. The results of which showed, that the
(pyrrolidin-1-yl)methyl side chain could be replaced by a
(piperidin-1-yl)methyl side chain, as demonstrated by
compounds 11, 14, or 15 on one hand and compounds
16, 17, or 18 on the other hand. An open-chain side
chain as found in amides 19 or 20, did not, however, give
highly potent compounds. Similarly, a change of the
core pyrrolidine ring resulted in most cases in less potent
compounds: The compounds with (R)-configuration
showed consistently lower activity than their respective
(S)-enantiomers as shown by compounds 11, 14, and 17
versus compounds 21, 22, or 23. Also, compound 24,
which is a racemic mixture, has a surprisingly low
potency, even though the only change in comparison
with amide 11 is the incorporation of a piperidine-
scaffold instead of a pyrrolidine scaffold. Compounds 25
and 26 are examples of cinnamic amides derived from
the two other racemic regioisomeric ((pyrrolid-
inyl)methyl)piperidines. Whereas amide 26 has almost no
This large variety of possible substitutents on the aro-
matic moiety of the cinnamic amides, gave us the
opportunity to choose substituents, which we considered
to be advantageous for the optimization of other
important parameters, such as lack of CYP inhibition,
plasma half life, or blood–brain barrier penetration.
R1
R1'
N
O
H/CH3
O
H/CH3
R1
( )n
NH
( )m
R1'
N
a)
( )
n N
HO
R
R
+
( )m
III
VI
VII
m = 1, 2
n = 0, 1, 2
Scheme 4. (a) EDAC, DHOBt, Et3N.

2606
B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
In this context, we speculated, that the introduction of
trifluoromethyl groups or trifluoromethoxy groups may
have a positive influence on the plasma half life of the
test compounds. Both trifluoromethyl––as in amides 14
or 17––and trifluoromethoxy––as in amides 15 or 18––
were substituents that can be found in compounds with
interestingly high in vitro potency at the hH3 receptor.
as the 1,2,4-triazol-1-yl group in 37. This very potent
compound was found to be equipotent to its analogue
38, where the heterocyclic ring was exchanged with a
phenyl ring.
Having investigated the influence of substitution on the
aromatic moiety, we finally turned our interest toward
the double bond. Substitution on the double bond of the
cinnamic amide is tolerated with small substituents at
the b-carbon: The methyl-substituted analogue 39 is
equipotent with the unsubstituted acryl amide 14. This
knowledge could be helpful, if metabolism at the double
bond should become a serious problem, and shielding of
the double bond is required.
On the other hand, we had concerns about the relatively
high hydrophobicity of these compounds, which may
give problems with unwanted pharmacokinetic proper-
ties such as low solubility or high distribution volume.39
As a consequence of the previous considerations alter-
native compounds were investigated. We were looking
for polar groups, which should not be too abundant in
nature, since we hoped this would enhance the proba-
bility of being inert to degradation by enzymes, and
thereby exhibit a prolonged plasma half life. Another
demand on these groups was that despite their polarity,
hydrogen-bonding capacity should be as low as possible,
which is considered to be a necessity for a reasonable
blood–brain barrier penetration.40–42 Keeping all these
considerations in mind, we thought that sulfones and
sulfonates could be good candidates as substitutents. In
fact the sulfonates 34 and 35 showed high potencies
between 6 and 8 nM as antagonists at the hH3 receptor.
Also the sulfone 36 gave encouraging results.
In summary, we have identified a group of moderately
potent hH3 antagonists in the class of cinnamic amides
of (aminomethyl)pyrrolidines. Interestingly, the potency
is widely independent of the substituent on the aromatic
moiety. However, when the aromatic group is omitted,
as in acrylamide 40, the potency drops significantly
(Table 1).
With such a high number of potent antagonists toward
the hH3 receptor, we investigated the ability of these
compounds to inhibit a number of cytochrome P450
enzymes as a counter-screen. We had observed inhibi-
tion with some of our early imidazole-containing com-
pounds as well as with some of the imidazole-free H3
antagonists, described in the literature.25 An inhibition,
Another possibility for a group with low polar surface
area (PSA) seemed to be heterocyclic substituents, such
Table 1. hH3-[35S]GTPc[S] binding assay
Entry
Ki (nM)
Cl
N
O
10
2148(ꢀ627)
N
O
N
O
11
10.0(ꢀ0.9)
196(ꢀ65)
N
Br
N
O
12
N
Cl
N
O
13
11.2(ꢀ1.4)
4.7(ꢀ0.4)
N
Cl
N
O
14
N
F
F
F

B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
2607
Table 1 (continued)
Entry
Ki (nM)
N
O
O
N
N
15
16
13.4(ꢀ1.9)
O
F
F
F
N
5.9(ꢀ1.0)
Br
N
O
17
18
11.8(ꢀ2.6)
14.2(ꢀ3.0)
N
F
F
F
N
O
N
F
O
F
F
H3C
H3C
N
N
O
O
19
80(ꢀ32)
N
O
F
H3C
H3C
F
F
F
20
21
111(ꢀ11)
57(ꢀ16)
N
O
F
F
N
N
N
Br
O
O
O
22
64(ꢀ11)
N
F
F
F
N
23
24
114(ꢀ20)
250(ꢀ55)
N
F
F
F
N
N
Br
O
25
26
N
N
N
34.3(ꢀ5.7)
Br
Br
O
1099(ꢀ517)
N
(continued on next page)

2608
B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
Table 1 (continued)
Entry
Ki (nM)
N
O
27
28
39.3(ꢀ13.5)
Br
N
O
Br
N
37.3(ꢀ10.1)
N
CH3
N
O
O
29
30
5.5(ꢀ2.4)
6.1(ꢀ1.0)
N
N
O
CH3
N
N
O
O
N
31
2.8(ꢀ0.7)
N
O
N
O
N
32
33
15.9(ꢀ7.2)
12.5(ꢀ3.1)
O
CH3
N
O
CH3
O
N
O
CH3
N
O
N
34
35
7.7(ꢀ1.4)
6.2(ꢀ0.8)
O
O
S
S
CH3
O
N
O
N
O
O
CH3
O
N
O
36
10.2(ꢀ1.1)
N
O
S
CH3
O
N
O
37
38
3.4(ꢀ0.3)
3.7(ꢀ1.3)
N
N
N
N
N
O
N

B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
2609
Table 1 (continued)
Entry
Ki (nM)
N
O
O
CH3
39
40
6.7(ꢀ2.0)
N
N
F
F
F
N
N
363(ꢀ183)
10.9(ꢀ5.5)
CH3
CH3
O
F
41
N
Br
resulting either from a real inhibitor or from a com-
petitive substrate behaving as a pseudoinhibitor, of
some of the cytochrome P450 subtypes can result in
serious problems in patients due to for example drug–
drug interactions. Since our goal was to discover potent
H3 antagonists to be used for clinical purposes, for
example for the treatment of attention deficit disorder,
Alzheimer’s disease or appetite regulation, we can
expect that these patients would typically take more
than one kind of drug. For this reason we wanted to
address this issue as early as possible in our research.
Hence, the compounds, which looked most promising in
the potency screening, were subjected to a test where the
inhibition values of three cytochrome P450 subtypes
(CYP2D6, CYP3A4, and CYP1A2) were determined at
a concentration of 20 lM. The observed data for the
inhibition are shown in Table 2. Four compounds,
namely amides 17, 30, 34, and 36, inhibit all three tested
subtypes only very little or not at all. Looking for a
common feature in these compounds, we concluded that
electron withdrawing substituents, such as trifluoro-
methyl, cyano, or methylsulfonyl, in the para-position of
the aromatic moiety might be beneficial for obtaining
low CYP inhibition. On the other hand, compounds
with a different common feature seem to be strong
CYP2D6 and CYP1A2 inhibitors: compounds like
amides 15 or 41, which both inhibit both of these two
subtypes more than 50%, bear lipophilic side chains on
the aromatic moiety. In general, halogen substitution on
the aromatic moiety results in compounds, which inhibit
CYP2D6 and CYP1A2 moderately, independently from
the position of substitution. This is shown in the series
of compounds 11, 13, 16 and 27. An interesting feature
was found for methoxy substitution. While amide 32,
bearing a methoxy group in the para-position inhibits
CYP2D6 with 36%, CYP3A4 with 28% and CYP1A2
with 7%, compound 29 and compound 33, with two
methoxy groups, are both weaker inhibitors with inhi-
bition values of 22%, 19%, and 4% for compound 29 and
of 12%, 18% and 0% for compound 33, respectively. The
sulfonate 34 shows only limited inhibitory effect.
Table 2. CYP-Inhibition
Entry
CYP2D6-
inhibition (%)
CYP3A4-
inhibition (%)
CYP1A2-
inhibition (%)
The very lipophilic phenyl substituent in compound 38
results in a relatively low inhibitory values, whereas the
triazole 37 exhibits much higher the effects on CYP2D6
and CYP1A2.
11
13
14
15
16
17
18
19
21
22
27
29
30
32
33
34
36
37
38
39
41
24
28
30
62
22
3
2
23
31
20
22
12
18
8
72
44
66
58
64
46
38
39
35
15
21
4
These observations cannot, however, describe the com-
plete picture: A comparison of amide 14 with amide 17
on one hand and amides 22 and 39 on the other hand
reveals large differences in the inhibition data despite the
same substituent on the aromatic moiety. One issue is
the stereochemistry on the acylated pyrrolidine ring. The
(S)-configured derivatives 11 and 14 are less potent
inhibitors than the (R)-configured analogues 21 and 22
for the CYP2D6. Surprisingly the order is just the
opposite for the inhibition of CYP1A2. The influence of
the ring size of the amine is unpredictable: In the pair of
the amides 11 and 16 almost no difference in inhibition
of CYP2D6 and CYP1A2 can be seen, whereas there is a
huge difference in the inhibition of CYP3A4. On the
other hand the piperidine analogue 17 shows in all three
tested cytochrome P450 subtypes a much more favor-
able profile than the pyrrolidine analogue 14. A
44
61
67
56
32
22
0
35
9
24
19
0
9
36
12
15
2
28
18
6
7
0
0
6
0
30
37
20
42
52
7
11
4
a
a
10
78
a Not determined.

2610
B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
comparison of compounds 15, 18, and 19 further shows,
that also the open chain amines, such as in amide 19 do
not influence the inhibitory effects in either direction
dramatically.
r-receptor and at the sodium channel, compound 14
inhibited the binding of the reference compounds by
77%, 86% and 73%, respectively, at a concentration of
10 lM, whereas for the desired binding to the hH3
receptor a Ki of 4.7 nM had been found.
In summary, we concluded, that it was not possible to
develop a clear SAR for cinnamic amides with respect to
CYP inhibition. However, by combination of the
screening results for potent H3 antagonists with the
CYP inhibition data, we had the possibility to identify a
number of very interesting candidates for further
screening. Examples of such as compounds are 14, 17,
18, 30, 34, and 36.
4. Experimental
4.1. [35S]GTPc[S] binding assay
CHO cells, stably expressing the human histamine H3
receptor as described in the literature,7;44 were harvested
and membranes were prepared by threefold homogeni-
zation in a 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethane-
sulfonic acid (HEPES) buffer (20 mM HEPES, 0.1–
10 mM EDTA; pH 7.4). The functional, antagonist
potency of hH3 antagonists was measured as their
ability to inhibit the binding of [35S]GTPc[S] in the
presence of 10 nM (R)-a-methylhistamine (RAMHA).
The test compound was diluted in assay buffer (20 mM
HEPES, 120 mM NaCl, 10 mM MgCl2, pH 7.4) at var-
ious concentrations followed by addition of 10 nM
RAMHA, 3 lM GDP, 2.5 lg membranes, 0.5 mg SPA
beads, and 0.1 nM [35S]GTPc[S]. After 2 h incubation at
room temperature with gentle shaking of the plate, the
plate was centrifuged at 370 RCF for 10 min and sub-
sequently the radioactivity was counted in a Cobra II
auto gamma topcounter. A number of 4–5 experiments
were run for each test compound.
3. Conclusion
The cinnamic amides of (S)-2-((pyrrolidin-1-yl)meth-
yl)pyrrolidines and (S)-2-((pyrrolidin-2-yl)methyl)-
piperidines are potent antagonists at the hH3 receptor.
The fact, that the effects on the hH3 receptor is only
influenced moderately by substituents on the aromatic
moiety, gave us the unique opportunity to optimize
further, in order to obtain compounds, that do not
inhibit three important CYP subtypes. It has to be
stressed, however, that a predictive understanding of the
inhibitory effects of the synthesized compounds on three
CYP subtypes could not be established. Despite these
problems we were able to identify amides 14, 17, 30, and
36 as very promising H3 antagonists. The in vitro
ADME parameters of some of these compounds will be
characterized further, as will their behavior in various
animal models. Surprisingly, the compounds that had
been identified by the described screening procedure
showed only moderate potency at the rat H3 receptor,
the receptor of the standard animal models (Table 3).
Large species differences have been described in the lit-
erature.43 However the reported compounds exhibited
greater potency toward the rat receptor than on the
human receptor. At this point it remains unclear, whe-
ther the compounds are active enough at the rat-H3
receptor in order to use rat-animal-models. On the other
hand, the observed selectivity seems to be quite prom-
ising: As shown in Table 3, no effects on the H1-, H2-, or
H4-receptor could be found for compounds 14 or 17.
Furthermore a screening for 75 different receptors or
enzymes at a concentration of 10 lM showed almost
exclusive selectivity for the H3 receptor for compound
14 (IC50 values >10 lM). At the 5HT1A receptor, the
4.2. Data analysis
The IC50 values of H3 antagonists were calculated by
nonlinear regression analysis using GraphPad Prism
(GraphPad Software, Inc.). The functional Ki values
for the H3 antagonists were calculated from the IC50
values using the Cheng–Prusoff relationship:
Ki ¼ IC50=ð1 þ ðS=EC50ÞÞ where S represents the con-
centration of RAMHA used (10 nM) and EC50 repre-
sents the mean EC50 value (ꢀSEM) of RAMHA in more
than 60 separate agonist [35S]GTPc[S] binding experi-
ments (i.e. 2.70 ꢀ 0.15 nM).
4.3. CYP Inhibition assay
The in vitro CYP subtype activity in the absence and
presence of a test compound (the potential CYP subtype
inhibitor) was determined using a CYP subtype selective
substrate (dextromethorphan for CYP2D6, erythromy-
cin for CYP3A4, and phenacetin for CYP1A2, respec-
tively). Incubations were utilized (200 lL, 37 ꢁC, 10 min)
containing human liver microsomes (HLM, 0.1 mg), [O-
methyl-14C]-dextromethorphan in the CYP2D6-assay
(total conc.: 3 lM ¼ Km), [N-methyl-14C]erythromycin
and erythromycin in the CYP3A4 assay (total conc.:
20 lM ¼ Km), or [O-ethyl-14C]phenacetin and phenacetin
in the CYP1A2-assay (total conc.: 40 lM ¼ Km), the
co-factor NADPH (1 mM) and the test compound
(20 lM). All incubations were performed in triplicate.
The HLM preparations used, were a pool of P15
Table 3. Binding to other histamine receptors
Entry
rH3 Ki
(nM)a
H1 Ki
(nM)b
H2 Ki
(nM)c
H4 Ki
(nM)d
14
17
30
36
53
131
61
>1000
>1000
>1000
>1000
>1000
>1000
e
e
e
e
e
e
45
a rH3-[35S]GTPc[S] binding-assay.
b H1 binding-assay, using 3H-pyrilamine as radioligand.
c H2 binding-assay, using 125I-aminopentidine as radioligand.
d H4 binding-assay, using [2,5-3H]histamine as radioligand.
e Not determined.

B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
2611
donors in order to obtain an average concentration of
CYP subtypes, which is known to differ markedly
between individuals.
(m, 4H); 3.55 (m, 2H); 8.75 (br, 1H); 8.95 (br, 1H); 10.05
(br, 1H).
4.7. rac-3-((Pyrrolidin-1-yl)methyl)piperidine
(3)
The metabolic conversion of [O-methyl-14C]-dextro-
methorphan, [N-methyl-14C]erythromycin, or [O-ethyl-
14C]phenacetin, respectively, were assessed by activated
charcoal extraction followed by liquid scintillation
counting of the supernatant. The thereby measured 14C-
formaldehyde reflected the metabolism of the selective
substrate by CYP subtype.
Compound 3 was prepared as described for compound
2, starting with rac-3-formylpiperidine 1-carboxylic acid
tert-butyl ester46 as starting material.
1H NMR (HCl salt, CDCl3) d 1.80–2.20 (m, 6H), 2.4–
3.2 (m, 9H); 3.50 (m, 3H); 3.75 (m, 1H); 9.30–9.90 (m,
2H).
4.4. Chemistry
(S)-1-((Pyrrolidin-2-yl)methyl)piperidine,27 (S)-2-((N,N-
diethylamino)methyl)pyrrolidine,26 (R)-2-((pyrrolidin-1-
yl)methyl)pyrrolidine,28 ((pyrrolidin-1-yl)methyl)piper-
idine,29 (methanesulfonic acid 4-formylphenyl ester,35
(E)-3-(4-trifluoromethylphenyl)but-2-enoic acid,31 (E)-4-
(methylsulfonyloxy)cinnamic acid,32 and (E)-4-(meth-
ylsulfonyl)cinnamic acid33;33;34 were prepared as
described in the literature.
4.8. (E)-3-(4-(1,2,4-Triazol-1-yl)phenyl)acrylic acid (6)
A mixture of 4-(1,2,4-triazol-1-yl)benzaldehyde (2.0 g,
11 mmol), malonic acid (1.8 g, 17 mmol) and piperidine
(0.159 mL, 1.6 mmol) in pyridine (12 mL) was heated to
90 ꢁC for 2.5 h. It was cooled to room temperature. A
mixture of concd hydrochloric acid and ice (1:4, 200 mL)
was added. The precipitate was collected by filtration. It
was recrystallized from methanol to give 1.9 g (76%) of
compound 6.
4.5. (R)-1-((pyrrolidin-2-yl)methyl)piperidine (1)
1H NMR (DMSO-d6) d 6.60 (d, 1H); 7.65 (d, 1H); 7.90
(AB, 4H); 8.30 (s, 1H); 9.40 (s, 1H); 12.50 (br, 1H).
(R)-1-((pyrrolidin-2-yl)methyl)piperidine (1) was pre-
pared analogously to the method described in the liter-
ature27 for (S)-1-((pyrrolidin-2-yl)methyl)piperidine.
4.9. (E)-3-(4-(Cyclopropylcarbonyl)phenyl)acrylic acid
(8)
1H NMR (CDCl3) d 1.30 (m, 1H); 1.40 (m, 2H); 1.55 (m,
4H); 1.70 (m, 3H); 1.85 (m, 1H); 2.25–2.60 (m, 6H); 2.80
(m, 1H); 3.00 (m, 1H); 3.25 (m, 1H).
A mixture of commercially available (4-bromophenyl)-
(cyclopropyl)methanone (7, 0.450 g, 2.00 mmol), palla-
dium acetate 49 mg, 0.220 mmol), triphenylphosphine
(55 mg, 0.21 mmol), methyl acrylate (0.43 g, 2.50 mmol)
and triethylamine (10 mL, 72 mmol) was heated to
100 ꢁC for 48 h in a closed reaction vial. The reaction
mixture was cooled to room temperature. The solid was
removed by filtration. A mixture of ice and 1 N hydro-
chloric acid was added to the liquid. The mixture was
stirred for 1 h at room temperature. It was extracted
with ethyl acetate (2 · 150 mL). The combined organic
layers were washed with a saturated aqueous solution of
sodium hydrogencarbonate (100 mL) and dried over
magnesium sulfate. The solvent was removed in vacuo.
The crude product was purified by flash chromatogra-
phy on silica (40 g) using a mixture of dichloromethane–
ethyl acetate–heptane (1:1:1) as eluent, to give 217 mg of
(E)-3-(4-(cyclopropylcarbonyl)phenyl)acrylic acid methyl
ester.
4.6. 4-((Pyrrolidin-1-yl)methyl)piperidine (2)
At 0 ꢁC, sodium triacetoxyborohydride45 (22.3 g,
105 mmol) was added to a mixture of 4-formylpiper-
idine-1-carboxylic acid tert-butyl ester (7 g, 35 mmol),
ꢀ
pyrrolidine (3.23 mL, 39 mmol) and 4 A molsieves in
dichloromethane (100 mL). Acetic acid (4 mL, 70 mmol)
was added. The reaction mixture was stirred for 16 h at
room temperature. The solids were removed by filtra-
tion. The filtrate was diluted with tert-butyl methyl ether
(100 mL) and washed with an 1 N aqueous solution of
sodium hydroxide (100 mL). The aqueous phase was
extracted with tert-butyl methyl ether (3 · 100 mL). The
combined organic layers were dried over magnesium
sulfate. The solvent was removed in vacuo. The crude
product was purified by flash chromatography on silica
(90 g), using ethyl acetate/heptane (1:1) and 5% trieth-
ylamine as eluent, to give 1.97 g of 4-((pyrroidin-1-yl)
methyl)piperidine carboxylic acid tert-butyl ester. This
was dissolved in ethyl acetate. A 2.8 M solution of
hydrochloric acid in ethyl acetate (60 mL) was added.
The reaction mixture was stirred for 1 h, to give com-
pound 2 as a hydrochloride salt, which was used for the
amide coupling without further purification.
1H NMR (CDCl3) d 1.05 (m, 2H); 1.25 (m, 2H); 2.65 (m,
1H); 3.85 (s, 3H); 6.55 (d, 1H); 7.62 (d, 2H); 7.75 (d,
1H); 8.05 (d, 2H).
A solution of lithium hydroxide (27 mg, 1.1 mmol) in
water (2.00 mL) was added to a solution of (E)-3-(4-
(cyclopropylcarbonyl)phenyl)acrylic acid methyl ester
(217 mg, 0.94 mmol) in 1,4-dioxane (2.00 mL). 1,4-
Dioxane was added until a clear solution was obtained.
The reaction mixture was stirred for 16 h at room
1H NMR (dihydrochloride salt, CDCl3) d 1.30–1.50 (m,
2H); 1.80–2.10 (m, 6H); 2.70–3.10 (m, 5H); 3.15–3.30

2612
B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
temperature. It was diluted with an 1 N aqueous
solution of sodium hydroxide (50 mL) and washed with
tert-butyl methyl ether (2 · 40 mL). The aqueous
solution was acidified with a 10% aqueous solution of
sodium hydrogen sulfate until pH 3 was obtained. It was
extracted with ethyl acetate (3 · 100 mL). The combined
organic layers were dried over magnesium sulfate. The
solvent was removed in vacuo to give 170 mg (39% over
two steps) of crude compound 8, which was used in the
next step without further purification.
(both d, together 1H); 7.40 (m, 2H); 7.50 (m, 2H); 7.65
(d, 1H); MS: calcd for [M þ H]þ: 363; found: 363.
4.12. 3-(4-Chlorophenyl)-1-((S)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)propan-1-one (12)
1H NMR (CDCl3, two sets of signals) d 1.70–2.20 (m,
8H); 2.30–2.80 (m, 6H); 2.90–3.05 (m, 4H); 3.20–3.60
(m, 2H); 3.80 and 4.25 (both m, together 1H); 7.10 (d,
2H); 7.25 (d, 2H). MS: calcd for [M þ H]þ: 321; found:
321.
1H NMR (DMSO-d6) d 1.05 (m, 4H); 2.95 (m, 1H); 6.70
(d, 1H); 7.65 (d, 1H); 7.85 (d, 2H); 8.05 (d, 2H); 12.60
(br, 1H).
4.13. (E)-3-(4-Chlorophenyl)-1-((S)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (13)
4.10. Typical procedure for amide formation: 1-(4-chloro-
phenyl)-4-((2S)-2-((pyrrolidin-1-yl)methyl)pyrrolidin-1-
yl)butane-1,4-dione (10)
1H NMR (HCl salt, DMSO-d6, two sets of signals) d
1.80–2.15 (m, 8H); 3.10, 3.20, 3.30, 3.45, and 3.55–3.85
(m, together 8H); 4.40 and 4.75 (both m, together 1H);
7.05 and 7.15 (both d, together 1H); 7.50 (m, 3H); 7.80
and 7.90 (both d, together 2H); 10.2 (br, 1H). MS: calcd
for [M þ H]þ: 319; found: 319.
At 0 ꢁC, 1-(3-dimethylaminopropyl)-3-ethylcarbodi-
imide hydrochloride salt (EDAC, 420 mg, 2.20 mmol)
was added to a solution of 3-(4-chlorobenzoyl)propionic
acid (470 mg, 2.20 mmol) and 3-hydroxy-1,2,3-benzo-
triazin-4(3H)-one (DOHBt, 360 mg, 2.20 mmol) in N,N-
dimethylformamide (2 mL) and dichloromethane
(2 mL). The reaction mixture was stirred for 20 min
at 0 ꢁC. A solution of the crude dihydrochloride salt
of (S)-2-((pyrrolidin-1-yl)methyl)pyrrolidine (500 mg,
2.20 mmol) in N,N-dimethylformamide (2 mL) and
triethylamine (2.15 mL, 15.4 mmol) were added succes-
sively. The reaction mixture was stirred for 16 h, while it
was warming up to room temperature. It was diluted
with ethyl acetate (100 mL) and washed with brine
(100 mL). The aqueous phase was dried over magnesium
sulfate. The solvent was removed in vacuo. The crude
product was purified by flash chromatography on silica
(40 g), using a mixture of dichloromethane–methanol–
25% aqueous ammonia (100:10:1) as eluent, to give
120 mg of compound 10.
4.14. (E)-1-((S)-2-((Pyrrolidin-1-yl)methyl)pyrrolidin-1-
yl)-3-(4-(trifluoromethyl)phenyl)propenone (14)
1H NMR (HCl salt, DMSO-d6, two sets of signals) d
1.80–2.15 (m, 8H); 3.10, 3.25, 3.30, 3.45, and 3.55–3.80
(all m, together 8H); 4.40 and 4.80 (both m, together
1H); 7.20 and 7.30 (both d, together 1H); 7.70
and 7.75 (both d, together 1H); 7.75 and 7.80 (both d,
together 2H); 7.95 and 8.10 (both d, together 2H);
10.25 (br, 1H).
MS: calcd for [M þ H]þ: 353; found: 353.
Elemental analysis for HCl salt: C19H23N2OF3ClÆ
HClÆ0.5H2O (353.40Æ36.46Æ0.5 18.02). Calcd: C, 57.36;
H, 6.33; Cl, 8.91; N, 7.04. Found: C, 57.56; H, 6.30; Cl,
8.95; N, 7.07.
1H NMR (CDCl3, two sets of signals) d 1.80–2.20 (m,
8H); 2.40–2.90 (m, 8H); 3.20–4.40 (m, 4H); 4.10
and 4.25 (both t, together 1H); 7.40 (d, 2H); 7.95 (d,
2H).
4.15. (E)-1-((S)-2-((Pyrrolidin-1-yl)methyl)pyrrolidin-1-
yl)-3-(4-(trifluoromethoxy)phenyl)propenone (15)
MS: calcd for [M þ H]þ: 349; found: 349.
1H NMR (CDCl3, two sets of signals) d 1.80 (m, 4H);
1.85–2.20 (m, 4H); 2.40–2.80 (m, 6H); 3.55–3.75 (m,
2H); 4.15 and 4.40 (both m, together 1H); 6.70 and 6.85
(both d, together 1H); 7.20 (d, 2H); 7.55 (d, 2H); 7.65 (d,
1H). MS: calcd for [M þ H]þ: 369; found: 369.
Compound 10 was transferred into its hydrochloride
salt, by dissolving it in ethanol (50 mL). 1 N hydrochloric
acid (12 mL) was added. The solvent was removed in
vacuo. The residue was dissolved in ethanol (50 mL). The
solvent was removed in vacuo. C19H25ClN2O2ÆHClÆ3H2O
(348.88Æ36.46 3Æ18.02). Calcd: C, 51.94; H, 7.34; N, 6.38.
Found: C, 51.31; H, 7.60; N, 7.08.
4.16. (E)-3-(4-Bromophenyl)-1-((S)-2-((piperidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (16)
4.11. (E)-3-(4-Bromophenyl)-1-((2S)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (11)
1H NMR (CDCl3, two sets of signals) d 1.45 (m, 2H); 1.55
(m, 4H); 2.85–2.10 (m, 4H); 2.15–2.70 (m, 6H); 3.55–3.75
(m, 2H); 4.15 and 4.40 (both m, together 1H); 6.70 and
6.95 (both d, together 1H); 7.40 (d, 2H); 7.50 (d, 2H);
7.60 (d, 1H). MS: calc. for [M þ H]+: calcd 377; found:
377.
1H NMR (CDCl3, two sets of signals) d 1.70–2.20 (m,
8H); 2.45–2.80 (m, 6H); 3.60 and 3.70 (both m, together
2H); 4.20 and 4.40 (both m, together 1H); 7.70 and 7.90

B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
2613
4.17. (E)-1-((S)-2-((Piperidin-1-yl)methyl)pyrrolidin-1-
yl)-3-(4-(trifluoromethyl)phenyl)propenone (17)
3.50–3.75 (m, 2H); 4.15 and 4.40 (both m, together 1H);
6.80 and 7.05 (both d, together 1H); 7.65 (AB, 4H); 7.70
(d, 1H). MS: calcd for [M þ H]þ: 367; found: 367.
1H NMR (CDCl3, two sets of signals) d 1.40 (m, 2H);
1.55 (m, 4H); 1.80–2.10 (m, 4H); 2.15–2.70 (m, 6H);
3.55–3.75 (m, 2H); 4.15 and 4.40 (both m, together 1H);
6.80 and 7.05 (both d, together 1H); 7.60 (m, 4H); 7.70
(d, 1H). MS: calcd for [M þ H]þ: 367; found: 367.
4.24. (E)-3-(4-Bromophenyl)-1-(2-((pyrrolidin-1-
yl)methyl)piperidin-1-yl)propenone (24)
1H NMR (CDCl3, two sets of signals) 1.35–1.90 (m,
10H); 2.40–2.90 (m, 7H); 3.90 and 4.25 (both m,
together 1H); 4.60 and 5.05 (both m, together 1H); 6.95
(d, 1H); 7.35 (d, 2H); 7.45–7.65 (m, 3H). MS: calcd for
[M þ H]þ: 377; found: 377.
4.18. (E)-1-((S)-2-((Piperidin-1-yl)methyl)pyrrolidin-1-
yl)-3-(4-(trifluoromethoxy)phenyl)propenone (18)
1H NMR (CDCl3, two sets of signals) d 1.45 (m, 2H); 1.55
(m, 4H); 1.85–2.10 (m, 4H); 2.15–2.70 (m, 6H); 3.50–3.75
(m, 2H); 4.15 and 4.40 (both m, together 1H); 6.70 and
6.90 (both d, together 1H); 7.20 (d, 2H); 7.55 (d, 2H); 7.65
(d, 1H). MS: calcd for [M þ H]þ: 383; found: 383.
4.25. (E)-3-(4-Bromophenyl)-1-(3-((pyrrolidin-1-
yl)methyl)piperidin-1-yl)propenone (25)
1H NMR (CDCl3, two sets of signals) d 1.20–4.25 (m,
19H); 4.35 and 4.55 (both d, together 1H); 6.90 and 7.20
(both d, together 1H); 7.30–7.55 (m, 4H); 7.60 (d, 1H).
MS: calcd for [M þ H]þ: 377; found 377.
4.19. (E)-1-((S)-2-(Diethylaminomethyl)pyrrolidin-1-yl)-
3-(4-(trifluoromethoxy)phenyl)propenone (19)
1H NMR (CDCl3, two sets of signals) d 1.05 (m, 6H);
1.85–2.15 (m, 4H); 2.15–2.80 (m, 6H); 3.50–3.75 (m,
2H); 4.10 and 4.30 (both m, together 1H); 6.70 and 6.90
(both d, together 1H); 7.20 (d, 2H); 7.55 (d, 2H); 7.65
and 7.66 (both d, together 1H). MS: calcd for [M þ H]þ:
371; found: 371.
4.26. 3-(4-Bromophenyl)-1-(4-((pyrrolidin-1-
yl)methyl)piperidin-1-yl)propenone (26)
1H NMR (CDCl3) d 1.20 (m, 2H); 1.80 (m, 5H); 1.90 (m,
2H); 2.35 (d, 2H); 2.50 (m, 4H); 2.80 (t, 1H); 3.10 (t,
1H); 4.10 (d, 1H); 4.70 (d, 1H); 6.90 (d, 1H); 7.35 (d,
2H); 7.50 (d, 2H); 7.55 (d, 1H). MS: calcd for [M þ H]þ:
377; found: 377.
4.20. (E)-1-((S)-2-(Diethylaminomethyl)pyrrolidin-1-yl)-
3-(4-(trifluoromethyl)phenyl)propenone (20)
1H NMR (CDCl3, two sets of signals) d 1.00 (m, 6H);
1.85–2.15 (m, 4H); 2.20–2.80 (m, 6H); 3.60 and 3.70
(both m, together 2H); 4.10 and 4.30 (both m, together
1H); 6.80 and 7.00 (both d, together 1H); 7.60 (AB, 2H);
7.70 and 7.71 (both d, together 1H). MS: calcd for
[M þ H]þ: 355; found: 355.
4.27. (E)-3-(3-Bromophenyl)-1-((S)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (27)
1H NMR (CDCl3, two sets of signals) d 1.70–1.85 (m,
4H); 1.90–2.20 (m, 5H); 2.40–2.75 (m, 6H); 3.60 (t, 1H);
4.15 and 4.40 (both m, together 1H); 6.70 and 6.95 (both
d, together 1H); 7.45 (m, 2H); 7.60 (d, 1H); 7.80 (t, 1H);
MS: calcd for [M þ H]þ: 363; found: 363.
4.21. (E)-3-(4-Bromophenyl)-1-((R)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (21)
1H NMR (CDCl3, two sets of signals) d 1.70–2.20 (m,
8H); 2.45–2.80 (m, 6H); 3.60 and 3.70 (both m, together
2H); 4.15 and 4.40 (both m, together 1H); 7.70 and 7.90
(both d, together 1H); 7.40 (m, 2H); 7.50 (m, 2H); 7.65
(d, 1H); MS: calcd for [M þ H]þ: 363; found: 363.
4.28. (E)-3-(2-Bromophenyl)-1-((S)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (28)
1H NMR (CDCl3, two sets of signals) d 1.50–1.90 (m,
4H); 1.90–2.20 (m, 4H); 2.50–2.85 (m, 6H); 3.55–3.80
(m, 2H); 4.15 and 4.40 (both m, together 1H); 6.65 and
6.85 (both d, together 1H);7.10–7.40 (m, 2H); 7.50–7.70
(m, 2H); 8.05 (d, 1H); MS: calcd for [M þ H]þ: 363;
found: 363.
4.22. (E)-1-((R)-2-((Pyrrolidin-1-yl)methyl)pyrrolidin-1-
yl)-3-(4-trifluoromethylphenyl)propenone (22)
1H NMR (CDCl3, two sets of signals) d 1.80 (m, 4H);
1.90–2.20 (m, 4H); 2.45–1.85 (m, 6H); 3.60 and 3.70
(both m, together 2H); 4.15 and 4.40 (both m, together
1H); 6.80 and 7.00 (both d, together 1H); 7.65 (AB, 4H);
7.70 (d, 1H); MS: calcd for [M þ H]þ: 353; found: 353.
4.29. (E)-3-(2,4-Dimethoxyphenyl)-1-((S)-2-((pyrrolidin-
1-yl)methyl)pyrrolidin-1-yl)propenone (29)
1H NMR (CDCl3, two sets of signals) d 1.75 (m, 4H);
1.85–2.20 (m, 4H); 2.45–2.75 (m, 6H); 3.50–3.75 (m,
2H); 3.82 (s, 3H); 3.85 (s, 3H); 4.15 and 4.40 (both m,
together 1H); 6.45 (m, 2H); 6.75 and 6.90 (both d, to-
gether 1H); 7.45 (dd, 1H); 7.85 and 7.90 (both d, to-
gether 1H). MS: calcd for [M þ H]þ: 345; found: 345.
4.23. (E)-1-((R)-2-((Piperidin-1-yl)methyl)pyrrolidin-1-
yl)-3-(4-(trifluoromethyl)phenyl)propenone (23)
1H NMR (CDCl3, two sets of signals) d 1.45 (m, 2H);
1.55 (m, 4H); 1.85–2.10 (m, 4H); 2.15–2.70 (m, 6H);

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B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
4.30. 4-[(E)-3-Oxo-3-((S)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)propenyl]benzonitrile (30)
4.34. Methanesulfonic acid 4-[(E)-3-oxo-3-((S)-2-((pyr-
rolidin-1-yl)methyl)pyrrolidin-1-yl)propenyl]phenyl ester
(34)
1H NMR (CDCl3, two sets of signals) d 1.75 (m, 4H);
1.85–2.20 (m, 4H); 2.40–2.75 (m, 6H); 3.55–3.75 (m,
2H); 4.15 and 4.40 (both m, together 1H); 6.80 and 7.00
(both d, together 1H); 7.55–7.70 (m, 5H). MS: calcd for
[M þ H]þ: 310; found: 310.
1H NMR (CDCl3, two sets of signals) d 1.75 (m, 4H);
1.85–2.20 (m, 4H); 2.40–2.80 (m, 5H); 3.15 (s, 3H); 3.50–
3.75 (m, 2H); 4.15 and 4.40 (m, 1H); 6.70 and 6.85 (both
d, together 1H); 7.30 (m, 2H); 7.55 (d, 2H); 7.65 (d, 1H).
MS: calcd for [M þ H]þ: 379; found: 379.
4.31. (E)-3-(4-(Cyclopropanecarbonyl)phenyl)-1-((S)-2-
((pyrrolidin-1-yl)methyl)pyrrolidin-1-yl)propenone (31)
4.35. Methanesulfonic acid 4-[(E)-3-oxo-3-((S)-2-((piper-
idin-1-yl)methyl)pyrrolidin-1-yl)propenyl]phenyl ester (35)
1H NMR (CDCl3, two sets of signals, broad signals) d
1.05 (m, 2H); 1.25 (m, 2H); 1.80 (m, 4H); 1.90–2.15 (m,
4H); 2.40–2.80 (m, 6H); 3.60 and 3.70 (both m, together
2H); 4.15 and 4.40 (both m, together 1H); 6.85 and 7.00
(both d, together 1H); 7.40 (d, 2H); 7.75 (d, 1H); 8.00
(m, 2H). MS: calcd for [M þ H]þ: 353; found: 353.
C22H28N2O2ÆHClÆ0.2H2O. Calcd: C, 67.32; H, 7.55; N,
7.14. Found: C, 67.28; H, 7.57; N, 7.12.
1H NMR (CDCl3, two sets of signals) d 1.45 (m, 2H);
1.55 (m, 4H); 1.70–2.15 (m, 4H); 2.15–2.70 (m, 6H);3.15
(s, 3H); 3.60 and 3.70 (both m, together 2H); 4.15 and
4.35 (both m, together 1H); 6.70 and 6.90 (both d, to-
gether 1H); 7.30 (d, 2H); 7.55 (d, 2H); 7.65 (d, 1H). MS:
calcd for [M þ H]þ: 393, found: 393.
4.36. (E)-3-(4-(Methylsulfonyl)phenyl)-1-((S)-2-((piper-
idin-1-yl)methyl)pyrrolidin-1-yl)propenone (36)
4.32. (E)-3-(4-Methoxyphenyl)-1-((S)-2-((piperidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (32)
1H NMR (CDCl3, two sets of signals) d 1.45 (m, 2H);
1.50–1.70 (m, 4H); 1.85–2.15 (m, 4H); 2.15–2.70 (m,
6H); 3.10 (s, 3H); 3.65 and 3.75 (both m, together 2H);
4.20 and 4.40 (both m, together 1H); 6.85 and 7.10 (both
d, together 1H); 7.70 (m, 3H); 7.95 (d, 2H). MS: calcd
for [M þ H]þ: 377; found: 377.
1H NMR (CDCl3, two sets of signals) d 1.45 (m, 2H);
1.55 (m, 4H); 1.85–2.10 (m, 4H); 2.15–2.70 (m, 6H);
3.55–3.75 (m, 2H); 3.85 (s, 3H); 4.15 and 4.40 (both m,
together 1H); 6.60 and 6.75 (both d, together 1H); 6.90
(m, 2H); 7.50 (d, 2H); 7.65 (d, 1H). MS: calcd for
[M þ H]þ: 329; found: 329.
4.37. (E)-1-((S)-2-((Piperidin-1-yl)methyl)pyrrolidin-1-
yl)-3-(4-(1,2,4-triazol-1-yl)phenyl)propenone (37)
4.33. (E)-3-(3,4-Dimethoxyphenyl)-1-((S)-2-((piperidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (33)
1H NMR (CDCl3, two sets of signals) d 1.40 (m, 2H);
1.55 (m, 4H); 1.80–2.15 (m, 4H); 2.15–2.70 (m, 6H); 3.60
and 3.70 (both m, together 2H); 4.20 and 4.40 (both m,
together 1H); 6.75 and 7.00 (both d, together 1H); 7.70
(m, 5H); 8.10 (s, 1H); 8.60 (s, 1H). MS: calcd for
[M þ H]þ: 366; found: 366.
1H NMR (CDCl3, two sets of signals) d 1.40 (m, 2H);
1.55 (m, 4H); 1.80–2.10 (m, 4H); 2.15–2.70 (m, 6H); 3.50–
3.75 (m, 2H); 3.90 (s, 6H); 4.15 and 4.40 (both m, to-
gether 1H); 6.55 and 6.75 (both d, J ¼ 15:2 Hz, together
1H); 6.85 (m, 1H); 7.10 (AB, 2H); 7.65 (d, J ¼ 15:2 Hz,
1H). MS: calcd for [M þ H]þ: 359; found. 359.
4.38. (E)-3-(Biphenyl-4-yl)-1-((S)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)propenone (38)
The hydrochloride salt of compound 33 was dissolved in
water (pH 5 for the solution) and left at room tempera-
ture. After one week only 18% of compound 33 was left,
while (Z)-3-(3,4-dimethoxyphenyl)-1-((S)-2-((piperidin-
1-yl)methyl)pyrrolidin-1-yl)propenone was found.
1H NMR (CDCl3, two sets of signals) d 1.70–2.20 (m,
8H); 2.45–2.80 (m, 6H); 3.60 and 3.70 (t and m, together
2H); 4.20 and 4.40 (both m, together 1H); 6.75 and 6.90
(both d, together 1H); 7.30–7.50 (m, 3H); 7.60 (m, 6H);
7.75 (d, 1H). MS: calcd for [M þ H]þ: 361; found: 361.
4.33.1. (Z)-3-(3,4-Dimethoxyphenyl)-1-((S)-2-((piperidin-
1H
1-yl)methyl)pyrrolidin-1-yl)propenone.
NMR
(CDCl3, two sets of signals) d 1.40 (m, 2H); 1.50–1.70
(m, 4H); 1.70–2.70 (m, 10H); 3.25 (m, 1H); 3.55 (m, 1H);
3.75 and 4.35 (both m, together 1H); 3.85, 3.87, 3.88 and
3.91 (all s, together 6H); 5.93 and 6.10 (both
d, J ¼ 12:7 Hz, together 1H) 6.50 and 6.51 (both
d, J ¼ 12:7 Hz, together 1H); 6.80 (m, 1H); 6.95
and 7.00 (both dd, together 1H) 7.10 and 7.15 (both
d, together 1H). MS: calcd for [M þ H]þ: 359; found:
359.
4.39. (E)-1-(((S)-2-((Pyrrolidin-1-yl)methyl)pyrrolidin-1-
yl)-3-(4-(trifluoromethyl)phenyl)but-2-en-1-one (39)
1H NMR (CDCl3, two sets of signals, broad signals) d
1.65–1.85 (m, 4H); 1.85–2.15 (m, 4H); 2.35–2.80 (m,
6H); 2.50 (s, 3H); 3.40–3.70 (m, 2H); 4.05 and 4.40 (both
m, together 1H); 6.25 and 6.50 (both s, together 1H);
7.55 (m, 2H); 7.65 (d, 2H). MS: calcd for [M þ H]þ: 367;
found: 367.

B. Peschke et al. / Bioorg. Med. Chem. 12 (2004) 2603–2616
2615
12. Krause, M.; Ligneau, X.; Stark, H.; Garbarg, M.;
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4171–4176.
4.40. (E)-4-Methyl-1-((S)-2-((pyrrolidin-1-
yl)methyl)pyrrolidin-1-yl)pent-2-en-1-one (40)
13. Ligneau, X.; Lin, J. S.; Vanni-Mercier, G.; Jouvet, M.;
Muir, J. L.; Ganellin, C. R.; Stark, H.; Elz, S.; Schunack,
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1H NMR (CDCl3, two sets of signals) d 1.05 (t, 6H);
1.75 (m, 4H); 1.85–2.15 (m, 5H); 2.35–2.70 (m, 6H);
3.40–3.60 (m, 2H); 4.05 and 4.30 (both m, together 1H);
6.05 and 6.15 (both d, together 1H); 6.90 and 6.92 (both
t, together 1H). MS: calcd for [M þ H]þ: 251; found:
251.
15. Vasudevan, A.; Conner, S. E.; Gentles, R. G.; Faghih, R.;
Liu, H. Q.; Dwight, W.; Ireland, L.; Kang, C. H.;
Esbenshade, T. A.; Bennani, Y. L.; Hancock, A. A.
Bioorg. Med. Chem. Lett. 2002, 12, 3055–3058.
16. Faghih, R.; Dwight, W.; Gentles, R.; Phelan, K.; Esben-
shade, T. A.; Ireland, L.; Miller, T. R.; Kang, C. H.;
Fox, G. B.; Gopalakrishnan, S. M.; Hancock, A. A.;
Bennani, Y. L. Bioorg. Med. Chem. Lett. 2002, 12, 2031–2034.
17. Faghih, R.; Dwight, W.; Black, L.; Liu, H. Q.; Gentles, R.;
Phelan, K.; Esbenshade, T. A.; Ireland, L.; Miller, T. R.;
Kang, C. H.; Krueger, K. M.; Fox, G. B.; Hancock, A. A.;
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4.41. (E)-3-(4-Bromo-2-fluorophenyl)-1-((S)-2-((pyrrol-
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1H NMR (CDCl3, two sets of signals) d 1.75 (m, 4H);
1.85–2.20 (m, 4H); 2.35–2.75 (m, 6H); 3.50–3.75 (m,
2H); 4.15 and 4.40 (both m, together 1H); 6.85 and 7.05
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18. Meier, G.; Ligneau, X.; Pertz, H. H.; Ganellin, C. R.;
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Acknowledgements
We thank Bjørn Bentzen, Charlotte Fjordager, Bent
Kolling, Rita Nielsen, Vivian Lind Tychsen, and
Dr. Magali Zundel for excellent technical support.
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