Novel 4-aryl-pyrido[1,2-c]pyrimidines with dual SSRI and 5-HT1A activity. Part 3

Article abstract of DOI:10.1016/j.ejmech.2010.10.026

A number of 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine with 3-(1,2,3,6-tetrahydro-pyridin-4-yl)-1H-indole or 2-methyl-3-(1,2,3,6-tetrahydro- pyridin-4-yl)-1H-indole residues were synthesized for further investigation of SAR in a group of pyrido[1,2-c]pyrimidine derivatives with dual 5-HT _1A/SERT activity. Compounds 8a-8p were found to be potent ligands for both 5-HT_1A and SERT with K_i ranging from 28,3 to 642 nM and 42,4 nM-1,8 μM, respectively. Moreover compounds 8a, 8b, 8c, 8d, 8e and 8g were found to be selective agonists, while 8i as an antagonist of 5-HT _1A presynaptic receptors in the inducible hypothermia test in mice.

Full text of DOI:10.1016/j.ejmech.2010.10.026

European Journal of Medicinal Chemistry 46 (2011) 142e149
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Novel 4-aryl-pyrido[1,2-c]pyrimidines with dual SSRI and 5-HT1A activity. part 3
,
a
a
a
a
Franciszek Herold a , Andrzej Chodkowski , qukasz Izbicki , Jadwiga Tur1o , Maciej Dawidowski ,
*
Jerzy Kleps a, Gabriel Nowak b c, Katarzyna Stachowicz b, Ma1gorzata Dyba1a c, Agata Siwek c,
,
Aleksander P. Mazurek d , Andrzej Mazurek , Franciszek Plucinski
,
e
e
e
ꢀ
a Department of Drug Technology, Faculty of Pharmacy, Medical University of Warsaw, ul. Banacha 1, 02-097 Warszawa, Poland
b Institute of Pharmacology, Polish Academy of Sciences, ul. Sme˛tna 12, 31-343 Kraków, Poland
c Chair of Pharmacobiology, Jagiellonian University, Collegium Medicum, Medyczna 9, PL 30-688 Kraków, Poland
d Department of Drug Chemistry, Medical University of Warsaw, ul. Banacha 1, 02-097 Warszawa, Poland
e National Medicines Institute, ul. Chełmska 30/34, 00-725 Warszawa, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
A number of 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine with 3-(1,2,3,6-tetrahydro-pyridin-4-yl)-
1H-indole or 2-methyl-3-(1,2,3,6-tetrahydro-pyridin-4-yl)-1H-indole residues were synthesized for
further investigation of SAR in a group of pyrido[1,2-c]pyrimidine derivatives with dual 5-HT1A/SERT
activity. Compounds 8ae8p were found to be potent ligands for both 5-HT1A and SERT with Ki ranging
from 28,3 to 642 nM and 42,4 nMe1,8 mM, respectively. Moreover compounds 8a, 8b, 8c, 8d, 8e and 8g
were found to be selective agonists, while 8i as an antagonist of 5-HT1A presynaptic receptors in the
inducible hypothermia test in mice.
Received 1 May 2010
Received in revised form
21 October 2010
Accepted 25 October 2010
Available online 29 October 2010
Keywords:
Antidepressants
Ó 2010 Elsevier Masson SAS. All rights reserved.
Pyrido[1,2-c]pyrimidines
Dual 5-HT1A/SERT activity
1. Introduction
inhibitor properties (Fig. 1.) [20,21]. Such an activity may lead to
a faster desensitization of the 5-HT1A autoreceptors, which in turn
5-HT1A receptors have a major role in the pathogenesis and
treatment of mood disorders [1,2]. Clinical studies have provided
evidence that a reduction in the 5-HT1A receptor function is asso-
ciated with depression [3e7]. Introduction of SSRIs has been
a breakthrough in the treatment of depression compared to TCAs or
MAO-Is. However, this group of drugs possesses some serious
drawbacks that reflect on their efficacy (i.e., long latency period,
moderate patient response, AEs).
It was found that the effects of the treatment with SSRIs can be
augmented by the concomitant use of 5-HT1A ligands (pindolol,
WAY 100635) [8e15]. These observations led to the development of
dual-action drugs as next-generation antidepressants [16e19].
In previous studies we described the synthesis and biological
evaluation of a number of presynaptic 5-HT1A agonists and SERT
could shorten the latency period, which is one of the major draw-
backs of the current therapy, in depression [22e27]. Possessing an
inhibitory action toward 5-HT transporters, these compounds can
be considered a good entry point for novel antidepressant candi-
dates [16e18,28].
In the course of our extensive synthetic studies we established
a facile synthetic route for obtaining unsaturated and saturated
derivatives of pyrido[1,2-c]pyrimidine containing 3-(1,2,3,6-tetra-
hydropyridil-4)-1H-indole moiety with good yields [19,20,29].
This method was applied in a synthesis of new 4-aryl-5,6,
7,8-tetrahydropyrido[1,2-c]pyrimidine with 3-(1,2,3,6-tetrahydro-
pyridin-4-yl)-1H-indole or 2-methyl-3-(1,2,3,6-tetrahydro-pyr-
idin-4-yl)-1H-indole residue, described herein.
2. Results and discussion
Several new derivatives of 4-aryl-tetrahydropyrido[1,2-c]pyrimi-
dine containing 3-(1,2,3,6-tetrahydro-pyridin-4-yl)-1H-indole or its
2-methyl derivative in the pharmacophore portion of the molecule
were obtained (Fig.2). In the 4-aryl-tetrahydropyrido[1,2-c]
pyrimidine system, an aryl substitute in compound 8a consisted of
a non-substituted phenyl ring, whereas, other derivatives possessed
Abbreviations: SERT, serotonin transporter; SAR, structure-activity relationship;
5-HT, serotonin; 8-OH-DPAT, 8-hydroxy-2-(di-n-propylamino)tetraline; Ki, inhib-
itor constant; TMS, tetramethylsilane; SSRIs, selective serotonin inhibitors; TCAs,
tricyclic antidepressants; MAO-Is, monoamine oxidase inhibitors; AE, adverse
event.
* Corresponding author.
E-mail address: franciszek.herold@wum.edu.pl (F. Herold).
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.10.026

F. Herold et al. / European Journal of Medicinal Chemistry 46 (2011) 142e149
143
binding assays ([3H]8-OH-DPAT and [3H]citalopram, respectively).
The data was analyzed using iterative curve-fitting routines to
obtain IC50 values (GraphPAD/Prism, Version 3.0 e San Diego, CA,
USA), which in turn were used to calculate the inhibition constant
Ki according to the Cheng-Prusoff formula (Table 1) [30].
4. SAR analysis
The binding values for compounds 8ae8p for the 5-HT1A
receptor and SERT were used for structure-activity relationship
analysis. The influence of the substituents bound to the 3-(1,2,3,6-
tetrahydropyridin-4-yl)-1H-indole moiety (eCH3 or eH at 2 posi-
tion), the influence of various substitutes at the ortho/para position
of the aryl ring, and the impact of the degree of saturation of the 3-
(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole system (compared to
ref. 1,2) were analyzed.
In binding tests for compounds 8a e8p a very high affinity of
derivatives 8g (Ki ¼ 19.9 nM), 8a (Ki ¼ 28.3 nM), and 8d
(Ki ¼ 32.4 nM) for 5-HT1A receptors was confirmed. The remaining
compounds possessed a high-to-weak binding activity with Ki
ranging from 41.3 nM to 642 nM (Table 1).
Fig. 1. Structure of pyrido[1,2-c]pyrimidines with dual 5-HT1A/SERT activity.
additional eF (8e, 8j), eCl (8f, 8o), eOCH3 (8g, 8k) or eCH3 (8h, 8l)
groups at the ortho position of the phenyl ring, as well as eF (8i, 8p),
eCl (8b), eOCH3 (8d, 8n) or eCH3 (8c, 8m) groups at the para
position.
All new compounds (8ae8p) were characterized by physical
constants, HRMS, 1H, and 13C NMR spectroscopy.
3. In vitro studies
When the effect of the substituent at the indole moiety on Ki
values was analyzed, it was found that compounds with a 3-(1,2,3,6-
The in vitro affinity of target compounds 8a e8p for 5-HT1A
tetrahydropyridin-4-yl)-1H-indole group possessed
a markedly
receptors and SERT in rat brain was assessed using radioligand
higher affinity to the 5-HT1A receptor than the analogous 2-methyl
Fig. 2. Route of synthesis of derivatives 8ae8p. Reagents and conditions: (i) 2-bromopyridine, KOH, DMSO,
D; (ii) H2SO4, CH3COOH, D; (iii) diethyl carbonate, EtONa, EtOH abs., D;
(iv) 1,4-dibromobutane, K2CO3, acetone,
D
; (v) H2, 10% Pt/C, CH3COOH, 40 ꢀC, 60 atm; (vi) 7a-7b, acetionitrile, K2CO3, KI,
D.

144
F. Herold et al. / European Journal of Medicinal Chemistry 46 (2011) 142e149
Table 1
Table 2
Ki [nM] values for compounds 8a e 8p.
The effect of tested compounds on the body temperature in mice.
Compound
R1
R2
R3
Ki 5-HT1A
Ki SERT
Treatment
Dose
(mg/kg)
D
t ꢁ SEM (ꢀC)
8a
8b
8c
8d
8e
8f
8g
8h
8i
8j
8k
8l
8m
8n
8o
8p
H
H
H
H
F
Cl
OCH3
CH3
H
H
Cl
CH3
OCH3
H
H
H
H
F
H
H
H
CH3
OCH3
H
H
H
H
H
H
H
H
H
28,3 ꢁ 0,5
48,6 ꢁ 5,0
46,2 ꢁ 3,7
32,4 ꢁ 0,9
41,3 ꢁ 0,3
62,3 ꢁ 5,4
19,9 ꢁ 0,5
112,2 ꢁ 1,1
62,3 ꢁ 4,8
303,0 ꢁ 25
319,0 ꢁ 17
642,0 ꢁ 1,4
278,7 ꢁ 16
152,9 ꢁ 7,9
393,4 ꢁ 1,7
113,8 ꢁ 5,2
81,7 ꢁ 6,2
44,1 ꢁ 2,5
42,4 ꢁ 5,2
50,4 ꢁ 2,6
68,4 ꢁ 6,3
147,0 ꢁ 5,9
134,3 ꢁ 3,9
69,1 ꢁ 6,2
47,0 ꢁ 0,4
30 min
60 min
90 min
120 min
Vehicle
8a
e
5
10
ꢂ0.0 ꢁ 0.0
ꢂ0.1 ꢁ 0.1
ꢂ0.0 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
ꢂ0.0 ꢁ 0.0
ꢂ0.1 ꢁ 0.1
ꢂ0.1 ꢁ 0.0
ꢂ0.7 ꢁ 0.0b ꢂ0.3 ꢁ 0.1
ꢂ1.1 ꢁ 0.2c ꢂ0.3 ꢁ 0.1
Vehicle
8b
e
ꢂ0.0 ꢁ 0.1
ꢂ0.3 ꢁ 0.1
ꢂ0.0 ꢁ 0.1
ꢂ0.4 ꢁ 0.2
ꢂ0.1 ꢁ 0.1
ꢂ0.1 ꢁ 0.0
ꢂ0.0 ꢁ 0.0
ꢂ0.1 ꢁ 0.0
ꢂ0.3 ꢁ 0.1
2.5
5
ꢂ1.0 ꢁ 0.3c ꢂ0.5 ꢁ 0.2a ꢂ0.4 ꢁ 0.2
H
Vehicle
8c
e
ꢂ0.1 ꢁ 0.1
ꢂ0.0 ꢁ 0.1
ꢂ0.1 ꢁ 0.1
ꢂ0.3 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
ꢂ0.0 ꢁ 0.0
ꢂ0.2 ꢁ 0.1
ꢂ0.1 ꢁ 0.0
ꢂ0.3 ꢁ 0.1
F
CH3
CH3
CH3
CH3
CH3
CH3
CH3
1,3 ꢁ 0,4 [
m
m
M]
M]
5
10
20
ꢂ0.5 ꢁ 0.1a ꢂ0.4 ꢁ 0.1
ꢂ0.6 ꢁ 0.1a ꢂ0.3 ꢁ 0.1
OCH3
CH3
H
H
Cl
1,3 ꢁ 0,3 [
882,0 ꢁ 22
ꢂ1.3 ꢁ 0.2c ꢂ0.9 ꢁ 0.2c ꢂ0.4 ꢁ 0.1
1,8 ꢁ 0,4 [
m
M]
M]
184,1 ꢁ 9,5
Vehicle
8d
e
ꢂ0.1 ꢁ 0.1
ꢂ0.1 ꢁ 0.1
ꢂ0.0 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
0.0 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
5
10
20
ꢂ0.6 ꢁ 0.2a ꢂ0.2 ꢁ 0.1
1,3 ꢁ 0,4 [
m
ꢂ0.8 ꢁ 0.2c ꢂ0.5 ꢁ 0.2a ꢂ0.3 ꢁ 0.1
H
F
147,4 ꢁ 14
ꢂ1.6 ꢁ 0.2c ꢂ0.9 ꢁ 0.2c ꢂ0.5 ꢁ 0.1a ꢂ0.3 ꢁ 0.1
Vehicle
8e
e
ꢂ0.0 ꢁ 0.1
ꢂ0.5 ꢁ 0.0
ꢂ0.1 ꢁ 0.0
ꢂ0.2 ꢁ 0.1
ꢂ0.1 ꢁ 0.1
ꢂ0.1 ꢁ 0.0
ꢂ0.1 ꢁ 0.1
ꢂ0.1 ꢁ 0.0
2.5
5
ꢂ1.3 ꢁ 0.2c ꢂ0.8 ꢁ 0.3c ꢂ0.5 ꢁ 0.2a ꢂ0.3 ꢁ 0.1
derivatives. Analyzing the effect of the substitution of the aryl ring in
4-aryl-tetrahydropyrido[1,2-c]pyrimidine, it could be noted that
substitution with eOCH3 both in para (8d) and ortho (8g) as well
as -CH3 at para position (8c) and fluorine in ortho position (8e) or lack
of substitution (8a), resulted in higher binding values than in the
remaining ligands.
Results of the studies on binding to SERT revealed that the high-
to-weak affinity of the tested compounds to the Ki values ranged
from 42.4 nM to 1.8 mM (Table 1).
Most of the methyl-substituted indole-derivatives possessed
a lower affinity than the non-substituted compounds (compound
8c vs. 8m, 8d vs. 8n, 8e vs. 8j, 8f vs. 8o, 8i vs. 8p). Analyzing
the influence of substitution in the aryl ring of the 4-aryl-tet-
rahydropyrido[1,2-c]pyrimidine moiety on the Ki value it was
found that the highest affinity to SERT was characteristic of
compounds with a fluorine atom at para (8i, 8p) position as well
as derivatives of the methoxy group in the para position
(8n, 8d).
Vehicle
8f
e
ꢂ0.0 ꢁ 0.0
ꢂ0.1 ꢁ 0.1
ꢂ0.1 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
ꢂ0.1 ꢁ 0.0
ꢂ0.1 ꢁ 0.1
ꢂ0.1 ꢁ 0.1
ꢂ0.0 ꢁ 0.0
ꢂ0.1 ꢁ 0.0
5
10
20
ꢂ0.5 ꢁ 0.1a ꢂ0.2 ꢁ 0.1
ꢂ0.7 ꢁ 0.1b ꢂ0.2 ꢁ 0.1
ꢂ1.0 ꢁ 0.2c ꢂ0.6 ꢁ 0.1a ꢂ0.2 ꢁ 0.1
Vehicle
8g
e
ꢂ0.0 ꢁ 0.1
ꢂ0.5 ꢁ 0.1a ꢂ0.3 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
ꢂ0.2 ꢁ 0.0
ꢂ0.2 ꢁ 0.1
ꢂ0.0 ꢁ 0.1
5
10
20
ꢂ0.8 ꢁ 0.2c ꢂ0.5 ꢁ 0.1a ꢂ0.3 ꢁ 0.1
ꢂ0.9 ꢁ 0.2c ꢂ0.5 ꢁ 0.2a ꢂ0.3 ꢁ 0.1
ꢂ0.7 ꢁ 0.2b ꢂ0.5 ꢁ 0.2a ꢂ0.2 ꢁ 0.1
Vehicle
12-OH-DPAT
WAY 100635 0.1
e
ꢂ0.0 ꢁ 0.0
ꢂ0.1 ꢁ 0.0
ꢂ0.1 ꢁ 0.1
ꢂ0.0 ꢁ 0.1
5
ꢂ1.4 ꢁ 0.1c ꢂ1.2 ꢁ 0.1c ꢂ0.7 ꢁ 0.1b ꢂ0.2 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
ꢂ0.1 ꢁ 0.1
ꢂ0.1 ꢁ 0.0
ꢂ0.1 ꢁ 0.1
The tested compounds were administered (ip) 30 min before the test. The absolute
mean body temperatures were within a range of 36 ꢁ 0.5 ꢀC; n ¼ 7e8 mice per
group, ap < 0.05, bp < 0.01, cp < 0.001 vs. respective vehicle.
Table 3
The effect of WAY 100635 on the hypothermia induced by the tested compounds in
mice.
Saturation of the tetrahydropyrido[1,2-c]pyrimidine system
decreased SERT inhibition compared to the unsaturated pyrido[1,2-
c]pyrimidine derivatives previously described in Part 1 [20].
However, the unsaturated 1,2,3,6-tetrahydropyridin-4-yl moiety
had an influence on lowering KiSERT values for 2-methyl-substituted
indole-derivatives compared to the saturated derivatives described
in Part 2 [21].
Compound and dose (mg/kg)
D
t ꢁ SEM (ꢀC)
30 min
60 min
Vehicle þ vehicle
ꢂ0.0 ꢁ 0.0
ꢂ1.1 ꢁ 0.1b
ꢂ0.5 ꢁ 0.2d
ꢂ0.1 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
ꢂ0.2 ꢁ 0.1
Vehicle þ 8a (10)
WAY 100635 (0.1) þ 8a (10)
Vehicle þ vehicle
ꢂ0.0 ꢁ 0.0
ꢂ1.1 ꢁ 0.1b
ꢂ0.2 ꢁ 0.1d
ꢂ0.0 ꢁ 0.0
ꢂ0.6 ꢁ 0.1a
ꢂ0.1 ꢁ 0.1d
Vehicle þ 8b (5)
WAY 100635 (0.1) þ 8b (5)
5. In vivo studies
Vehicle þ vehicle
ꢂ0.1 ꢁ 0.0
ꢂ1.1 ꢁ 0.1b
ꢂ0.4 ꢁ 0.1d
ꢂ0.0 ꢁ 0.0
ꢂ0.4 ꢁ 0.1
ꢂ0.2 ꢁ 0.0
Vehicle þ 8c (20)
WAY 100635 (0.1) þ 8c (20)
Compounds with the most promising affinity for both the
5-HT1A receptor and SERT (8ae8e, 8g, and 8i) were further evalu-
ated in mice for their agonist/antagonist properties toward pre- and
postsynaptic 5-HT1A receptors, using the inducible hypothermia
and forced swimming tests, respectively [31e34]. These pharma-
cological models are commonly used for evaluating 5-HT1A
receptor function.
Vehicle þ vehicle
ꢂ0.1 ꢁ 0.0
ꢂ1.2 ꢁ 0.2b
ꢂ0.3 ꢁ 0.1d
ꢂ0.0 ꢁ 0.1
ꢂ0.7 ꢁ 0.1a
ꢂ0.2 ꢁ 0.1
Vehicle þ 8d (20)
WAY 100635 (0.1) þ 8d (20)
Vehicle þ vehicle
ꢂ0.0 ꢁ 0.0
ꢂ1.3 ꢁ 0.2b
ꢂ0.2 ꢁ 0.1d
ꢂ0.0 ꢁ 0.1
ꢂ0.8 ꢁ 0.2b
ꢂ0.1 ꢁ 0.1c
Vehicle þ 8e (5)
WAY 100635 (0.1) þ 8e (5)
Vehicle þ vehicle
ꢂ0.0 ꢁ 0.1
ꢂ1.0 ꢁ 0.2b
ꢂ0.3 ꢁ 0.1d
0.0 ꢁ 0.1
ꢂ0.6 ꢁ 0.1a
ꢂ0.1 ꢁ 0.1c
Compounds 8a-8e, 8g, similar to 8-OH-DPAT, induced hypo-
thermia in mice (Table 2), whereas, 8i (data not shown), just as
WAY 100635, did not change body temperature in mice (Table
2). The hypothermia induced by compounds 8a (10 mg/kg), 8b
(5 mg/kg), 8c (20 mg/kg), 8d (20 mg/kg), 8e (5 mg/kg), and 8g
(20 mg/kg) was attenuated by WAY 100635 (0.1 mg/kg) (Table
3). At the same time, the decrease in body temperature
induced by 8-OH-DPAT (5 mg/kg) was completely blocked by
WAY 100635 (0.1 mg/kg) (Table 3, 4). Therefore, the decrease
in mouse body temperature, produced by 8a-8e and 8g could
Vehicle þ 8g (20)
WAY 100635 (0.1) þ 8g (20)
Vehicle þ vehicle
ꢂ0.1 ꢁ 0.1
ꢂ1.4 ꢁ 0.1b
ꢂ0.2 ꢁ 0.1d
ꢂ0.1 ꢁ 0.1
ꢂ1.2 ꢁ 0.1b
ꢂ0.1 ꢁ 0.0d
Vehicle þ 8-OH-DPAT (5)
WAY 100635 (0.1)þ8-OH-DPAT(5)
WAY 100635 was administered (sc) 15 min before the investigated compounds,
n ¼ 7e8 mice per group. The test was performed 30 min after injection of the tested
compounds (ip). The absolute mean body temperatures were within
a range
36.0 ꢁ 0.5 ꢀC, ap < 0.01, bp < 0.001 vs. respective vehicle þ vehicle group, cp < 0.01,
dp < 0.001 vs. respective vehicle þ compound group.

F. Herold et al. / European Journal of Medicinal Chemistry 46 (2011) 142e149
145
Table 4
compounds were considered to have a dual 5-HT1A and SERT
activity. In vitro receptor binding studies of newly synthesized
ligands revealed a very high to low binding affinity for 5-HT1A
receptors, as well as a high-to-weak binding affinity for SERT. The Ki
values for both the 5-HT1A receptor and SERT showed that
compounds 8a-8e, 8g and 8i were characterized by the highest
affinity among the new derivatives.
The rest of the described ligands bound both to the 5-HT1A
receptor and SERT with moderate or slight strength and were
characterized by Ki values ranging from intermediate to very high.
It was confirmed that the presence of the non-substituted indole
residue, as well as the fluorine atom at the ortho position or -OCH3
at ortho/para or the -CH3 group at the para position of the phenyl
group in the aryl ring of the 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]
pyrimidine system, had an impact on the affinity toward 5-HT1A
receptors and SERT.
The effect of 8i and WAY 100635 on the 8-OH-DPAT (5 mg/kg)-induced hypothermia
in mice.
Treatment and dose (mg/
kg)
D
t ꢁ SEM (ꢀC)
15 min
30 min
45 min
60 min
Vehicle þ vehicle
ꢂ0.1 ꢁ 0.1 ꢂ0.0 ꢁ 0.0 ꢂ0.1 ꢁ 0.0 ꢂ0.1 ꢁ 0.1
ꢂ1.1 ꢁ 0.1b ꢂ1.4 ꢁ 0.1b ꢂ0.8 ꢁ 0.1a ꢂ0.4 ꢁ 0.1
ꢂ0.7 ꢁ 0.2a ꢂ1.6 ꢁ 0.2bd ꢂ1.1 ꢁ 0.2bd ꢂ0.6 ꢁ 0.1ac
Vehicle þ 8-OH-DPAT
8i (20) þ 8-OH-DPAT
Vehicle þ vehicle
ꢂ0.0 ꢁ 0.0 ꢂ0.1 ꢁ 0.1 ꢂ0.1 ꢁ 0.1 ꢂ0.0 ꢁ 0.1
Vehicle þ 8-OH-DPAT (5) ꢂ1.3 ꢁ 0.1b ꢂ1.4 ꢁ 0.1b ꢂ0.7 ꢁ 0.1a ꢂ0.2 ꢁ 0.1
WAY100635(0.1)þ8-OH- ꢂ0.1 ꢁ 0.1d ꢂ0.1 ꢁ 0.1d ꢂ0.1 ꢁ 0.1d ꢂ0.1 ꢁ 0.1d
DPAT
8i was administered (ip) 45 min, while WAY 100635 (sc) 15 min prior to 8-OH-DPAT,
n ¼ 7e8 mice per group. The absolute mean initial body temperatures were within
the range of 36.0 ꢁ 0.5 ꢀC, ap < 0.01, bp < 0.001 vs. respective vehicle þ vehicle
group, cp < 0.01, dp < 0.001 vs. respective vehicle þ 8-OH-DPAT.
It was also found that the degree of saturation pyridine moiety
bound to the indole had an influence on KiSERT values for 2-methyl-
substituted indole-derivatives.
Results of behavioral studies confirmed that synthesized ligands
possess anticipated agonistic activity toward presynaptic 5-HT1A
receptors, while displaying no postsynaptic action.
be regarded as a measure of its presynaptic 5-HT1A receptor
agonistic activity. Compound 8i (20 mg/kg) attenuated the effect
of 8-OH-DPAT (5 mg/kg) in mice (in the first 15 min), therefore,
8i could be regarded as an antagonist of presynaptic 5-HT1A
receptor (Table 4).
Compounds 8a, 8d, and 8g have been successfully docked to the
5-HT1A model receptor without any steric strains (Fig. 3) [35]. 8a
forms a pretty strong hydrogen bond with Asp30; similarly, 8d
interacts with Asp30 and Asn386, and 8g with Asn386. The affinity of
8a, 8d, and 8g ligands to the serotonin transporter SERT was also
investigated. All three ligands were efficiently docked to the binding
site of SERT, not encountering any steric hindrances (Fig. 4) [35]. The
poses of the ligands, except 8g, inside the binding SERT pocket
seemed to be strongly stabilized by hydrogen bonds formed between
8dandAsp400, Lys490, Glu493, andsimilarly between 8aandLys490
and Glu493. Compound 8g does not bind with SERT via hydrogen
bonds, which may prove its lower affinity to SERT than the 8a and 8d
ligands.
Compounds 8b (2.5 and 5 mg/kg), 8c (10 and 20 mg/kg), 8d (10
and 20 mg/kg), 8e (2.5 and 5 mg/kg), and 8i (10 and 20 mg/kg) were
ineffective in the forced swimming test (data not shown). 8-OH-
DPAT at doses of 1 mg/kg and 2 mg/kg reduced by 45 and 57%,
respectively, the immobility time of mice (F(2,26)
p < 0.0001, data not shown).
¼
53.92,
6. Conclusion
Several new 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine
derivatives possessing 3-(1,2,3,6-tetrahydropyrid-4-yl)-1H-
indole group or its 2-methyl derivatives were synthesized. These
a
Fig. 3. Compound 8d inside the binding 5HT1A pocket. Black dash line denotes hydrogen bond.

146
F. Herold et al. / European Journal of Medicinal Chemistry 46 (2011) 142e149
Fig. 4. Compound 8a inside the binding SERT pocket. Black dash line denotes hydrogen bond.
7. Experimental protocols
is, bromobutylpyrido[1,2-c]pyrimidine-derivatives 6a-i (0.0026 mol)
and 1,2,3,6-tetrahydro-pyridin-4-yl-indoles 7a-b (0.0026 mol), as well
as K2CO3 (0.005 mol), 70 ml of acetonitrile, and a catalytic amount of KI
were stirred and refluxed for four to 5 h. The reaction time was
monitored using TLC. After cooling, the mixture was filtered, and the
filtrate was evaporated to dryness. The crude residue was purified by
crystallization from acetonitrile or by flash chromatography, using
a mixture of CH2Cl2/MeOH (97:3 v/v). Proper fractions were identified
by TLC and evaporated to dryness, giving analytically pure compounds
8aep.
7.1. Chemistry
7.1.1. General remarks
The melting points were determined on an Electrothermal 9100
apparatus with open capillary tubes, and were uncorrected. The
infrared spectra were recorded on a Shimadzu FTIR-8300 spec-
trometer. 1H and 13C-NMR spectra were obtained on a Bruker
AVANCE DMX 400WB instrument in CDCl3 (chemical shifts were
reported in
d units). Coupling constants (J) were in hertz (Hz) and
the internal reference was TMS. For the two-dimensional experi-
ments, the pulse sequences, acquisition, and processing parameters
were taken from the standard Bruker software library. ESI-HRMS
spectra were obtained on Marimer (PE Biosystems) instrument.
Flash column chromatography was carried out on Merck Silica
gel 60 (230e400 mesh ASTM) using the solvent methylene chlo-
ride/methanol (99:1, 97:3, 95:5, v/v). Thin layer chromatography
was run on Merck Silica gel 60 F254 plates, mobile phase of dioxane,
toluene, ethanol, and 25% NH4OH (6,0:3,2:0,5:0,2, v/v). Compounds
were visualized by UV light (254 nm).
8. NMR data
8.1. 2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-yl]-butyl}-
4-phenyl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-1,3-dione (8a)
The title compound was isolated as a white powder, yield: 45%;
m.p. 175e176 ꢀC. 1H NMR (500 MHz)
d
: 1.70 (q, 3J ¼ 6.5, C-6H2), 1.82
(m, C-2xH2, C-3xH2), 1.93 (q, 3J ¼ 6.5, C-7H2), 2.53 (t, 3J ¼ 6.5, C-5H2),
2.66 (ps, CdH2), 2.88 (t, C-4xH2), 3.00 (ps, CeH2), 3.48 (ps, CaH2),
3.95 (t, 3J ¼ 6.5, C-8H2), 4.07 (t, 3J ¼ 6.5, C-1xH2), 6.02 (ps, CbH), 7.04
(d, 3J ¼ 2.0, C-2”H), 7.12 (td, 3J ¼ 8.0, 4J ¼ 1.0, C-5”H), 7.18 (td, C-6”H),
7.21 (dt, 3J ¼ 7.0, 4J ¼ 1.5, C-20H, C-6’H), 7.33 (tt, 3J ¼ 7.5, 4J ¼ 1.5, C-
4’H), 7.40 (m, C-30H, C-50H, C-7”H), 7.77 (d, 3J ¼ 7.5, C-4”H), 8.92 (bs,
NH). HRMS (ESI) calculated for C31H35N4O2:494.6273 (M þ H)þ
found 494.6294.
7.1.1.1. Preparation of 2-(4-bromobutyl)-4-aryl-5,6,7,8-tetrahydro-
pyrido[1,2-c]pyrimidine-1,3-diones (6a-i). The starting compounds
2a-i, 3a-i, 4a-i, 5a-i, and 6a-i were obtained according to proce-
dures described in [20,21,29,36,37].
7.1.1.2. Preparation of 3-(1,2,3,6-tetrahydro-pyridin-4-yl)-1H-indole
(7a). The starting compounds 7a were obtained according to
procedures described in [38].
8.2. 4-(4-chlorophenyl)-2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-
pyridin-1-yl]-butyl}-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-1,3-
dione (8b)
7.1.1.3. Preparation of 2-methyl-3-(1,2,3,6-tetrahydro-pyridin-4-yl-
1H-indole (7b). The starting compound 7b was obtained according
to procedures described in [39].
The title compound was isolated as a white powder, yield: 55%;
m.p.139e140 ꢀC. 1H NMR (500 MHz) : 1.68 (m, C-6H2, C-3xH2),1.76
d
(q, C-2xH2), 1.91 (q, 3J ¼ 6.5, C-7H2), 2.50 (m, C5-H2, CdH2), 2.55 (ps,
C-4xH2), 2.70 (t, 3J ¼ 6.0, CeH2), 3.20 (pd, CaH2), 3.92 (t, 3J ¼ 6.5, C-
8H2), 4.06 (t, 3J ¼ 7.0, C-1xH2), 6.17 (ps, CbH), 7.10 (d, 3J ¼ 2.5, C-2”H),
7.13 (m, C-30H, C-50H, C-5”H), 7.17 (td, 3J ¼ 7.0, 4J ¼ 1.0, C-6”H), 7.36
(dt, 3J ¼ 8.5, 4J ¼ 2.0, C-20H, C-6’H), 7.87 (d, 3J ¼ 7.5, C-4”H), 8.41 (bs,
7.1.1.4. General procedure for synthesis of 2-{4-[4-(1H-indol-3-yl)-
(3,6-dihydro-2H-pyridin-1-yl]-butyl}-4-aryl-5,6,7,8-tetrahydro-pyr-
ido[1,2-c]pyrimidine-1,3-diones (8a-p). Appropriate substrates, that

F. Herold et al. / European Journal of Medicinal Chemistry 46 (2011) 142e149
147
NH). HRMS (ESI) calculated for C31H34N4O2Cl: 529.2365 (M þ H)þ
8.7. 2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-yl]-butyl}-
4-(4-methoxyphenyl)-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-
found 529.2345.
1,3-dione (8g)
8.3. 2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-yl]-butyl}-
4-(4-tolyl)-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-1,3-dione
(8c)
The title compound was isolated as a white powder, yield: 63%;
m.p.158e159 ꢀC. 1H NMR (500 MHz) : 1.70 (m, C-6H2, C-3xH2),1.76
d
(q, C-2xH2),1.90 (q, 3J ¼ 6.5, C-7H2), 2.42 (t, 3J ¼ 6.0, C-5H2), 2.56 (pd,
C-4xH2), 2.70 (t, 3J ¼ 6.0, CeH2), 3.20 (d, 3J ¼ 2.0, CaH2), 3.76 (s, OCH3),
3.92 (m, C-8H2), 4.06 (m, C-1xH2), 6.17 (pt, CbH), 6.93 (d, 3J ¼ 8.0, C-
30H), 6.99 (td, 3J ¼ 7.5, 4J ¼ 1.0, C-50H), 7.10 (m, C-4’H, C-2”H), 7.12 (td,
3J ¼ 8.0, 4J ¼ 1.0, C-5”H), 7.17 (td, 3J ¼ 7.0, 4J ¼ 1.0, C-6”H), 7.33 (m, C-
6’H, C-7”H), 7.88 (d, 3J ¼ 8.0, C-4”H), 8.35 (bs, NH). HRMS (ESI)
calculated for C32H37N4O3: 525.2860 (M þ H)þ found 525.2858.
The title compound was isolated as a white powder, yield: 62%;
m.p. 177e178 ꢀC. 1H NMR (500 MHz)
d
: 1.70 (q, 3J ¼ 6.5, C-6H2), 1.79
(m, C-2xH2, C-3xH2), 1.92 (q, 3J ¼ 6.5, C-7H2), 2.36 (s, CH3), 2.54
(t, 3J ¼ 6.5, C-5H2), 2.66 (ps, CdH2), 2.81 (ps, C-4xH2), 2.96 (ps, CeH2),
3.44 (ps, CaH2), 3.94 (t, 3J ¼ 6.5, C-8H2), 4.06 (t, 3J ¼ 6.5, C-1xH2), 6.05
(ps, CbH), 7.09 (m, C-30H, C-50H, C-2”H), 7.12 (m, 3J ¼ 7.0, 4J ¼ 1.5, C-
5”H), 7.18 (td, 3J ¼ 8.5, 4J ¼ 1.5, C-6”H), 7.20 (m, C-20H, C-6’H), 6.05 (ps,
CbH), 7.80 (d, 3J ¼ 8.0, C-4”H), 8.78 (bs, NH). HRMS (ESI) calculated
for C32H37N4O2: 508.6538 (M þ H)þ found 508.6527.
8.8. 2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-yl]-butyl}-
4-(2-tolyl)-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-1,3-dione
(8h)
8.4. 2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-yl]-butyl}-
4-(4-methoxyphenyl)-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-
1,3-dione (8d)
The title compound was isolated as a white powder, yield: 59%;
m.p. 174e175 ꢀC. 1H NMR (500 MHz)
d
: 1.70 (q, 3J ¼ 6.5, C-6H2), 1.79
(m, C-2xH2, C-3xH2), 1.92 (q, 3J ¼ 6.5, C-7H2), 2.39 (s, CH3), 2.54
(t, 3J ¼ 6.5, C-5H2), 2.66 (ps, CdH2), 2.81 (ps, C-4xH2), 2.92 (ps, CeH2),
3.48 (ps, CaH2), 3.94 (t, 3J ¼ 6.5, C-8H2), 4.09 (t, C-1xH2), 6.05 (ps,
CbH), 7.08 (m, C-30H, C-50H, C-2”H), 7.10 (m, 3J ¼ 7.0, 4J ¼ 1.5, C-5”H),
7.17 (td, 3J ¼ 8.5, 4J ¼ 1.5, C-6”H), 7.20 (d, C-6’H), 6.05 (ps, CbH), 7.80
(d, 3J ¼ 8.0, C-4”H), 8.78 (bs, NH). HRMS (ESI) calculated for
C32H37N4O2: 508.6538 (M þ H)þ found 508.6537.
The title compound was isolated as a white powder, yield: 59%;
m.p. 175e177 ꢀC. 1H NMR (400 MHz) : 1.67 (m, C-6H2, C-3xH2), 1.76
d
(m, C-2xH2), 1.89 (q, 3J ¼ 6.3, C-7H2), 2.51 (m, C-5H2, C-4xH2, CbH2),
2.67 (pt, CaH2), 3.19 (m, CeH2), 3.79 (s, OCH3), 3.91 (t, 3J ¼ 6.4, C-
8H2), 4.07 (t, 3J ¼ 7.2, C-1xH2), 6.15 (m, CdH2), 6.91 (d, C-30H, C-50H),
3
7.04 (d, 3J ¼ 2.4, C-2”H), 7.10 (d, J ¼ 8.8, C-20H, C-6’H), 7.10 (m, C-
5”H), 7.15 (td, 3J ¼ 8.1, 4J ¼ 1.2, C-6”H), 7.31 (d, 3J ¼ 8.0, C-7”H), 7.86
8.9. 4-(4-fluorophenyl)-2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-
pyridin-1-yl]-butyl}-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-1,3-
dione (8i)
(d, 3J ¼ 7.9, C-4”H), 8.64 (bs, NH). 13C NMR (400 MHz)
d: 18.6 (C-6),
21.7 (C-7), 24.6 (C-2x), 25.7 (C-3x), 26.7 (C-5), 29.0 (Cb), 41.6 (C-1x),
42.6 (C-8), 50.3 (Ca), 55.2 (OCH3), 58.2 (C-4x), 111.3 (C-7”), 112.0 (C-
4), 114.0 (C-30, C-50), 117.7 (Cd), 118.9 (C-3”), 119.7 (C-2”), 120.6 (C-
4”), 121.5 (C-5”), 121.8 (C-6”), 125.2 (C-3”a), 125.5 (C-1’), 129.8 (Cc),
131.8 (C-20, C-6’), 136.8 (C-7”a), 149.6 (C-4a), 151.7 (C-1), 159.0 (C-
4’), 162.2 (C-3). HRMS (ESI) calculated for C33H39N4O3: 538.6798
(M þ H)þ found 538.6805.
The title compound was isolated as a white powder, yield: 58%;
m.p.150e151 ꢀC. 1H NMR (500 MHz) : 1.68 (m, C-6H2, C-3xH2), 1.74
d
(q, C-2xH2), 1.91 (q, 3J ¼ 6.5, C-7H2), 2.50 (m, C-5H2, CdH2), 2.56 (ps,
C-4xH2), 2.70 (t, 3J ¼ 6.0, CeH2), 3.20 (d, 3J ¼ 2.5, CaH2), 4.06 (t,
3J ¼ 7.0, C-1xH2), 6.17 (ps, CbH), 7.05e7.20 (m, 7H, C-2”H, C-5”H, C-
6”H), 7.34 (d, 3J ¼ 8.0, C-7”H), 7.88 (d, 3J ¼ 8.0, C-4”H), 8.34 (bs, NH).
HRMS (ESI) calculated for C31H34N4O2F: 513.2660 (M þ H)þ found
513.2684.
8.5. 4-(2-fluorophenyl)-2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-
pyridin-1-yl]-butyl}-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-1,3-
dione (8e)
8.10. 4-(2-fluorophenyl)-2-{4-[4-(2-methyl-1H-indol-3-yl)-3,6-
dihydro-2H-pyridin-1-yl]-butyl}-5,6,7,8-tetrahydropyrido[1,2-c]
pyrimidine-1,3-dione (8j)
The title compound was isolated as a white powder, yield: 65%;
m.p. 181e182 ꢀC 1H NMR (500 MHz) : 1.63 (m, C-6H2, C-3xH2), 1.76
d
(q, C-2xH2), 1.91 (q, 3J ¼ 6.5, C-7H2), 2.51 (m, C-5H2, CdH2), 2.52 (ps,
C-4xH2), 2.71 (t, 3J ¼ 6.0, CeH2), 3.20 (d, 3J ¼ 2.5, CaH2), 4.01 (t,
3J ¼ 7.0, C-1xH2), 6.19 (ps, CbH), 7.09e7.25 (m, 7H, C-2”H, C-5”H, C-
6”H), 7.34 (d, 3J ¼ 8.0, C-7”H), 8.01 (d, 3J ¼ 8.0, C-4”H), 8.42 (bs, NH).
HRMS (ESI) calculated for C31H34N4O2F: 513.2660 (M þ H)þ found
513.2655.
The title compound was isolated as a white powder, yield: 42%;
m.p.164e165 ꢀC. 1H NMR (500 MHz) 1H NMR (500 MHz)
d: 1.64
(q, 3J ¼ 7.0, C-6H2), 1.72 (m, C-2xH2, C-3xH2), 1.91 (q, 3J ¼ 7.0, C-7H2),
2.42 (s, CH3), 2.50 (t, 3J ¼ 7.0, C-5H2), 2.68 (m, C-4xH2, CdH2), 2.86 (t,
CeH2), 3.27 (ps, CaH2), 3.91 (t, 3J ¼ 6.5, C-8H2), 4.10 (t, 3J ¼ 7.5, C-
1xH2), 5.62 (m, CbH) 7.03 (m, 3J1 ¼ 8.0, 3J2 ¼ 7.0, 4J ¼ 1.0, C-5”H),
7.00 (m, C-20H, C-50H, C-6”H), 7.12 (m, C-30H, C-6’H), 7.25 (dt,
3J ¼ 8.0, 4J¼5J¼1.0, C-7”H), 7.53 (d, 3J ¼ 8.0, C-4”H), 8.25 (bs, NH).
HRMS (ESI) calculated for C32H36N4O2F: 526.6443 (M þ H)þ found
526.6438.
8.6. 4-(2-chlorophenyl)-2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-
pyridin-1-yl]-butyl}-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-1,3-
dione (8f)
The title compound was isolated as a white powder, yield: 57%;
8.11. 2-{4-[4-(1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-yl]-butyl}-
4-(4-methoxyphenyl)-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-
1,3-dione (8k)
m.p. 172e173 ꢀC 1H NMR (400 MHz)
d: 1.65 (m, C-5H2), 1.79 (m, C-
2xH2), 1.91 (m, C-7H2), 2.38 (m, C-5H2), 2.56 (m, C-4xH2, CbH2), 2.75
(pt, CaH2), 3.21 (Pd, CeH2), 3.85 (m, C-8H), 4.08 (t, C-1xH2), 5.68
(bps, CdH), 7.02 (td, 3J ¼ 6.9, 4J ¼ 1.0, C-6”H), 7.05 (td, 3J ¼ 7.4,
4J ¼ 1.1, C-5”H), 7.22 (m, C-6’H, C-7”H), 7.29 (m, C-4’H, C-50H), 7.44
(dd, 3J ¼ 6.6, 4J ¼ 2.7, C-30H), 7.54 (d, 3J ¼ 7.7, C-4”H), 8.16 (bs, NH).
HRMS (ESI) calculated for C31H34N4O2Cl: 529.2365 (M þ H)þ found
529.2339.
The title compound was isolated as a white powder, yield: 51%;
m.p. 182e183 ꢀC.1H NMR (500 MHz)
d: 1.71 (m, C-6H2), 1.76 (m, C-
2xH2, C-3xH2), 1.93 (q, C-7H2), 2.40 (s, CH3), 2.43 (t, 3J ¼ 6.5, C-5H2),
2.67 (ps, C-4xH2, CdH2), 2.86 (ps, CeH2), 3.32 (ps, CaH2), 3.77
(s, OCH3), 3.93 (m, C-8H2), 4.06 (t, 3J ¼ 7.0, C-1xH2), 5.63 (ps, CbH2),

148
F. Herold et al. / European Journal of Medicinal Chemistry 46 (2011) 142e149
6.93 (dd, 3J ¼ 8.5, 4J ¼ 1.0, C-30H), 6.99 (td, 3J ¼ 7.5, 4J ¼ 1.0, C-50H),
7.04 (td, 3J ¼ 8.0, 4J ¼ 1.0, C-5”H), 7.10 (m, C-6’H, C-6”H), 7.26
(d, 3J ¼ 7.0, C-7”H), 7.33 (4d, 3J1 ¼ 8.5, 3J2 ¼ 6.0, 4J ¼ 1.5, C-4’H), 7.53
(d, 3J ¼ 7.5, C-4”H), 8.06 (bs, NH). HRMS (ESI) calculated for
C33H39N4O3: 539.3017 (M þ H)þ found 539.3038.
2xH2), 1.91 (m, C-7H2), 2.37 (s, CH3), 2.38 (m, C-5H2), 2.58 (m, C-
4xH2, CbH2), 2.75 (pt, CaH2), 3.21 (Pd, CeH2), 3.89 (m, C-8H(2)), 3.96
(m, 2J ¼ 13.8, 3J ¼ 6.4, C-8H(1)), 4.07 (t, 3J ¼ 7.1, C-1xH2), 5.66 (bps,
CdH), 7.02 (td, 3J ¼ 7.4, 4J ¼ 1.1, C-5”H), 7.06 (td, 3J ¼ 6.9, 4J ¼ 1.0, C-
6”H), 7.20 (m, C-6’H, C-7”H), 7.28 (m, C-4’H, C-50H), 7.44 (dd,
4
3J ¼ 6.6, J ¼ 2.7, C-30H), 7.54 (d, 3J ¼ 7.7, C-4”H), 8.16 (bs, NH). 13
C
8.12. 2-{4-[4-(2-methyl-1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-
yl]-butyl}-4-(2-tolyl)-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-
1,3-dione (8l)
NMR (400 MHz) d
: 12.8 (CH3), 18.4 (C-6), 21.8 (C-7), 24.1 (C-2x), 25.6
(C-3x), 26.3 (C-5), 30.1 (Cb), 41.3 (C-1x), 42.9 (C-8), 50.4 (Ca), 58.1 (C-
4x), 110.0 (C-4), 110.2 (C-7”), 114.7 (C-3”), 119.1 (C-5”), 119.2 (C-4”),
120.8 (C-6”), 122.6 (Cd), 127.1 (C-50), 127.6 (C-3”a), 129.4 (C-4’),
129.6 (C-30), 130.4 (Cc), 131.0 (C-7”a), 132.4 (C-1’), 132.5 (C-6’), 135.0
(C-20, C-2”), 150.4 (C-4a), 151.7 (C-1), 161.2 (C-3). HRMS (ESI)
calculated for C31H34N4O2Cl: 529.0723 (M þ H)þ found 529.0730.
The title compound was isolated as a white powder, yield: 74%;
m.p.162e163 ꢀC. 1H NMR (500 MHz)
d
: 1.69 (m, C-6H2, C-3xH2),1.76
x
0
(q, C-2 H2), 1.91 (m, C-7H2), 2.14 (s, CH3-C2”), 2.37 (s, CH3-C2 ), 2.44
(m, C-5H2), 2.57 (t, 3J ¼ 7.5, C-4xH2), 2.60 (pd, CdH2), 2.75 (t, 3J ¼ 5.5,
CeH2), 3.21 (d, 3J ¼ 3.0, CaH2), 3.93 (m, C-8H2), 4.07 (t, 3J ¼ 7.0, C-
1xH2), 5.65 (ps, CbH), 7.00e7.10 (m, C-30H, C-5”H, C-6”H), 7.17e7.27
(m, C-6’H, C-7”H), 7.54 (d, 3J ¼ 7.5, C-4”H), 8.16 (bs, NH). HRMS (ESI)
calculated for C33H39N4O2: 523.3068 (M þ H)þ found 523.3063.
8.16. 4-(4-fluorophenyl)-2-{4-[4-(2-methyl-1H-indol-3-yl)-3,6-
dihydro-2H-pyridin-1-yl]-butyl}-5,6,7,8-tetrahydropyrido[1,2-c]
pyrimidine-1,3-dione (8p)
The title compound was isolated as a white powder, yield: 63%;
m.p. 164e165 ꢀC. 1H NMR (500 MHz)
d
: 1.71 (q, 3J ¼ 7.0, C-6H2), 1.76
8.13. 2-{4-[4-(2-methyl-1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-
yl]-butyl}-4-(4-tolyl)-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine-
1,3-dione (8m)
(m, C-2xH2, C-3xH2), 1.92 (q, 3J ¼ 7.0, C-7H2), 2.39 (s, CH3), 2.51
(t, 3J ¼ 7.0, C-5H2), 2.66 (m, C-4xH2, CdH2), 2.85 (t, CeH2), 3.30 (ps,
CaH2), 3.94 (t, 3J ¼ 6.5, C-8H2), 4.06 (t, 3J ¼ 7.5, C-1xH2), 5.62 (m,
CbH) 7.03 (m, 3J1 ¼ 8.0, 3J2 ¼ 7.0, 4J ¼ 1.0, C-5”H), 7.08 (m, C-30H, C-
50H, C-6”H), 7.18 (m, C-20H, C-6’H), 7.25 (dt, 3J ¼ 8.0, 4J¼5J¼1.0, C-
7”H), 7.53 (d, 3J ¼ 8.0, C-4”H), 8.20 (bs, NH). HRMS (ESI) calculated
for C32H36N4O2F: 526.6443 (M þ H)þ found 526.6450.
The title compound was isolated as a white powder, yield: 52%;
T.t. 168e170 ꢀC. 1H NMR (400 MHz) : 1.68 (m, C-6H2, C-3xH2), 1.76
d
(m, C-2xH2), 1.90 (q, 3J ¼ 6.6, C-7H2), 2.35 (s, C-10H3), 2.38 (s, C-
9H3), 2.52 (m, C-5H2, CdH2), 2.58 (m, CeH2), 2.71 (t, 3J ¼ 5.7, C-4xH2),
3.18 (m, CaH2), 3.92 (t, 3J ¼ 6.3, C-8H2), 4.06 (t, 3J ¼ 7.3, C-1xH2), 5.68
(m, CbH), 7.04 (m, C-5”H, C-6”H), 7.08 (dt, 3J ¼ 8.1, 4J ¼ 1.7, C-30H, C-
50H), 7.20 (m, C-20H, C-6’H, C-7”H), 7.56 (d, 3J ¼ 7.8, C-4”H), 8.03 (bs,
9. Pharmacology
NH). 13C NMR (400 MHz)
d: 12.8 (C-10), 18.6 (C-6), 21.2 (C-9), 21.8
9.1. In vitro experiments
(C-7), 24.6 (C-2x), 25.8 (C-3x), 26.7 (C-5), 30.6 (Cb), 41.6 (C-1x), 42.6
(C-8), 50.6 (Ca), 53.3 (Ce), 58.5 (C-4x), 110.2 (C-7”), 112.4 (C-4), 115.0
(C-3”), 119.3 (C-4”), 119.3 (C-5”), 120.9 (C-6”), 123.3 (Cd), 127.7 (C-
3”a), 129.2 (C-20, C-6’), 130.3 (C-7”), 130.3 (Cc), 130.6 (C-30, C-50),
130.9 (C-1’), 135.1 (C-2”), 137.4 (C-4’), 149.5 (C-4a), 151.8 (C-1), 162.1
(C-3). HRMS (ESI) calculated for C33H39N4O2: 522.6804 (M þ H)þ
found 522.6809.
All compounds were tested for their affinity towards 5-HT1A
and SERT receptors according to procedures described previously
[20,21].
9.2. In vivo experiments
All the experimental procedures were approved by the Local
Bioethics Commission at the Institute of Pharmacology, Polish
Academy of Sciences in Kraków.
Compounds 8a, 8b, 8c, 8d, 8e, 8f, 8g, and 8i were tested in
induced hypothermia test in mice as well as compounds 8b, 8c, 8d,
8e, and 8i were tested in forced swimming test in mice according to
procedures described previously [20,21].
8.14. 2-{4-[4-(2-methyl-1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-
yl]-butyl}-4-(4-methoxyphenyl)-5,6,7,8-tetrahydropyrido[1,2-c]
pyrimidine-1,3-dione (8n)
The title compound was isolated as a white powder, yield: 42%;
m.p.142e143 ꢀC. 1H NMR (400 MHz) : 1.67 (m, C-6H2, C-3xH2),1.76
d
(bq, C-2xH2), 1.89 (q, 3J ¼ 6.5, C-7H2), 2.36 (s, CH3), 2.52 (m, C-5H2,
C-4xH2), 2.57 (bps, CbH2), 2.71 (pt, CaH2), 3.17 (pd, CeH2), 3.79 (s,
OCH3), 3.92 (t, 3J ¼ 6.3, C-8H2), 4.07 (t, 3J ¼ 7.2, C-1xH2), 5.67 (bps,
CdH2), 6.91 (pd, C-30H, C-50H), 7.02 (td, 3J ¼ 6.9, 4J ¼ 1.0, C-5”H), 7.06
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