Synthesis and adrenolytic activity of 1-(1H-indol-4-yloxy)-3-(2-(2-methoxy phenoxy)ethylamino)propan-2-ol analogs and its enantiomers. Part 2

Article abstract of DOI:10.1016/j.ejmech.2009.07.012

The synthesis of (2RS)-1-(5-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol and (2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol and its enantiomers, analogs of 1-(1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol ((RS)-9) is described. Compounds were tested for electrographic, antiarrhythmic, hypotensive and spasmolytic activities as well as for α₁-, α₂- and β₁-adrenoceptors binding affinities. The antagonist potency of the new compounds was compared with carvedilol and (RS)-9.

Full text of DOI:10.1016/j.ejmech.2009.07.012

European Journal of Medicinal Chemistry 44 (2009) 5103–5111
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
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Short communication
Synthesis and adrenolytic activity of 1-(1H-indol-4-yloxy)-3-(2-(2-methoxy
phenoxy)ethylamino)propan-2-ol analogs and its enantiomers. Part 2
a
,
a
a
b
*
´
_
´
´
Grazyna Groszek , Agnieszka Nowak-Krol , Tomasz Wdowik , Dariusz Swierczynski ,
**
Marek Bednarski c, Monika Otto c, Maria Walczak d, Barbara Filipek c
,
a Faculty of Chemistry, Rzeszo´w University of Technology, 6 Powstan´co´w Warszawy Avenue, 35-959 Rzeszo´w, Poland
b Institute of Physical Chemistry, Polish Academy of Sciences, 44/52 Kasprzaka, 01-224 Warszawa, Poland
c Laboratory of Pharmacological Screening, Jagiellonian University Medical College, 9 Medyczna, 30-689 Krako´w, Poland
d Department of Pharmacokinetics and Physical Pharmacy, Jagiellonian University Medical College, 9 Medyczna, 30-689 Krako´w, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of (2RS)-1-(5-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-
2-ol and (2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol and
its enantiomers, analogs of 1-(1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol
((RS)-9) is described. Compounds were tested for electrographic, antiarrhythmic, hypotensive and
spasmolytic activities as well as for a1-, a2- and b1-adrenoceptors binding affinities. The antagonist
potency of the new compounds was compared with carvedilol and (RS)-9.
Received 17 January 2009
Received in revised form
12 July 2009
Accepted 16 July 2009
Available online 21 July 2009
Ó 2009 Elsevier Masson SAS. All rights reserved.
Keywords:
Synthesis
Enantiomers
a1-, a2- and b1-Adrenoceptor antagonists
Cardiovascular and spasmolytic activities
1. Introduction
oxide (NO), antioxidant action, b2-agonistic action, Ca2þ entry
blockade and a1-blockade [2].
b
-Adrenolytic drugs have an established position in cardiovas-
In the last decade, a new generation of
tional -adrenoceptor blocking activity was introduced to therapy.
The -blockers (bucindolol, carvedilol, labetalol) have vaso-
dilating properties via relaxation of arterial smooth muscle, with no
reflex tachycardia, as a result of -adrenoceptor blockade. They
have also beneficial effects on the regular circulation in contrast to
classic -blockers [3].
Carvedilol, (2RS)-1-(9H-carbazol-4-yloxy)-3-(2-(2-methox-
yphenoxy)ethylamino) propan-2-ol, is a non-selective -adreno-
b-blockers with addi-
cular disorders’ treatment. Since development of this class of drugs
in the late 50s of XX century, they are administered in the therapy
of hypertension, coronary artery disease, arrhythmia, myocardial
infarct and since several years in heart failure [1]. However, some
adverse side effects, such as proatherosclerotic actions, peripheral
circulatory and respiratory disturbances, erectile dysfunction,
hypoglycemia during diabetic therapy, provocation of coronary
vasospasm, and impaired quality of life, have limited their clinical
a
a/b
b
b
b
use.
b
-Blockers, on the other hand, may increase the risk of severe
ceptor blocking agent which is most commonly used for treating
primary hypertension and stable angina pectoris because of its
vasodilating action [4,5]. Although originally used to treat hyper-
tension, subsequent studies have revealed that carvedilol has effi-
cacy in many other disease processes. Carvedilol improves the
symptom profile in patients with heart failure and stable angina
pectoris, reduces secondary cardiac events after myocardial infarc-
tion, decreases experimental infarct size after myocardial ischemia
and reperfusion injury, and favorably reduces portal pressures in
experimental models of cirrhosis [5,6]. Extensive investigations
have revealed that this agent significantly improves the morbidity of
the patients suffering from chronic heart failure [7].
hypoglycemia in patients with diabetes and hypertension because
they blunt autonomic warning symptoms of hypoglycemia. The
concern that
against their use in patients with diabetes. Recently, much atten-
tion is being paid to -blockers that possess vasodilator actions
b-blockers may mask hypoglycemia has militated
b
produced through different mechanisms, such as release of nitric
* Corresponding author. Tel.: þ48 17 8651751; fax: þ48 17 8543655.
** Corresponding author. Tel.: þ48 12 6205531; fax: þ48 12 6205552.
E-mail addresses: ggroszek@prz.edu.pl (G. Groszek), mffilipe@cyf-kr.edu.pl
(B. Filipek).
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.07.012

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G. Groszek et al. / European Journal of Medicinal Chemistry 44 (2009) 5103–5111
Seeking for structures with potential circulatory activity, we
suggested competitive binding. The results are summarized in
Table 1.
have focused our attention on the carvedilol analogue, compound
(RS)-9 (Fig. 1). The synthesis of this compound (racemate and
enantiomers) was described in Part 1 of the series [8]. (RS)-9 has the
characteristic structural fragment of each b1-adrenergic blocking
agent, namely aminopropan-2-ol moiety. In addition, it contains
indole moiety instead of the carbazole one, which is specific for
carvedilol.
In this part, we report on the preparation of two analogs of
(RS)-9: (2RS)-1-(5-methoxy-1H-indol-4-yloxy)-3-(2-(2-methox-
yphenoxy)ethylamino)propan-2-ol and (2RS)-1-(7-methoxy-1H-
indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol,
as well as their enantiomers. They have methoxy group introduced
to indole aromatic ring into position 5 or 7 (Fig. 2). We also present
the results of in vitro binding affinity to a1-, a2 and b1-adrenergic
receptors, antiarrhythmic and hypotensive activities of these
compounds.
3.2. Effect on normal electrocardiogram (ECG) in vivo in rats
The effect on ECG intervals and heart rate was determined for all
compounds in the same dose of 1 mg kgꢀ1
.
Racemic mixture and both enantiomers of compound 7a
administered iv decreased heart rate by 10–15% up to 15 min after
administration. Compounds (RS)-7a and (S)-7a prolonged P–Q
interval and only enantiomer S of compound 7a slightly prolonged
QRS complex (Table 2). Racemic mixture of compound 7b slightly
prolonged QRS, whereas enantiomer R of compound 7b consider-
ably changed the ECG pattern by significantly decreasing the
number of cardiac beats per minute and prolonged P–Q interval
and QRS complex. Racemic mixture and enantiomer R of compound
7b did not significantly affect the normal ECG in anesthetized rats.
2. Chemistry
3.3. Effect on adrenaline-induced arrhythmia in rats
In anesthetized rats, iv injections of adrenaline (20 m )
g kgꢀ1
The synthesis of target compounds is outlined in Fig. 2.
In the designed synthetic pathway, indole 5 was the key inter-
mediate. The procedure we used was similar to that described by
Fukuyama et al. [9], but we had to modify it to obtain compound 5b.
It comprised: (i) change of protective group from acetyl to benzyl
for compound 3b; (ii) modification of Knoevenagel reaction
conditions, step (d), leading to product 4; and (iii) reductive elim-
ination, step (e), to obtain indole derivative 5. For last two steps, we
applied the procedure as described in Part 1 [8]. Products 7 were
obtained both as racemic mixtures and as individual enantiomers.
To confirm, that deprotection of hydroxyl group took place in ortho
position relative to aldehyde group in substrate 1, X-ray analysis
was made for single crystals of compounds 3b and 7a. The crystal
structures are illustrated by the ORTEP diagrams in Figs. 3 and 4.
caused sinus bradycardia (100%), atrioventricular disturbances,
ventricular and supraventricular extrasystoles (100%) which led to
death of approximately 50% of animals. The tested compounds
administered 15 min prior to adrenaline injection decreased the
number of premature ventricular and supraventricular beats and
reduced mortality.
The ED50 values, a dose producing a 50% inhibition of premature
ventricular beats, in the adrenaline-induced arrhythmia are pre-
sented in Table 3. The compounds administered 15 min before
adrenaline prevented and/or reduced in a statistically significant
manner the number of premature ventricular beats. Compound 7a
and its enantiomers exhibited important antiarrhythmic effects
with ED50 values ranging between 0.38 and 0.53 mg kgꢀ1. The
second tested compound 7b and its enantiomers diminished the
occurrence of extrasystoles and reduced mortality with ED50 values
3. Pharmacological results
ranging between 0.16 and 0.38 mg kgꢀ1
.
3.1. Radioligand receptor binding assay for
-adrenergic receptors
a- and
b
3.4. Influence on blood pressure in rats
The affinity of compounds 7a and 7b and their enantiomers to
Hypotensive activity of compounds 7a and 7b (as racemic
mixture and both enantiomers) was determined after iv adminis-
tration to normotensive anesthetized rats.
the catecholamines binding side of a1-, a2- and b1-adrenoceptors
was measured as a rate of specific displacement of [3H]Prazosin,
[3H]Clonidine and [3H]CGP12177 at the concentrations of 0.2 nM,
2 nM and 0.2 nM, respectively. Compound 7a and its enantiomers
inhibited [3H]Prazosin binding with Ki ranging from 60.9 to
168.8 nM, [3H]Clonidine binding with Ki ranging from 108.8 to
277.2 nM and [3H]CGP12177 binding with Ki ranging from 59.3
to 530.6 nM to cortical a1-, a2- and b1-adrenoceptors, respectively.
Compound 7b and its enantiomers displaced [3H]Prazosin and
[3H]Clonidine from cortical binding sites in low concentration
range (Ki ¼ 11.3–45.8 nM and 43–60.9 nM, respectively). These
compounds also displaced [3H]CGP12177 from its binding sites in
After iv administration hypotensive activity was balanced for
each form of compound 7a. Both enantiomers and racemic mixture
significantly decreased the systolic (12–25%) and diastolic (13–30%)
blood pressures throughout the whole observation period in the
range of doses 0.25–1.0 mg kgꢀ1. In the lowest dose (0.125 mg kgꢀ1
)
of compound 7a and its enantiomers the hypotensive activity dis-
appeared (Fig. 5).
Compound 7b as a racemic mixture in the range of doses 0.25–
1.0 mg kgꢀ1 decreased the systolic blood pressure (7–18%)
throughout the whole observation period and the diastolic blood
pressure (8–19%). In the lower dose (0.125 mg kgꢀ1) this compound
upper concentrations (Ki ¼ 0.89–3.4
mM). The shape of the curves
O
O
*
*
O
N
H
O
N
H
OH
OH
O
O
N
H
N
H
Carvedilol
(RS)-9
Fig. 1. Chemical structure of carvedilol and (RS)-9.

G. Groszek et al. / European Journal of Medicinal Chemistry 44 (2009) 5103–5111
5105
OH
OBn
O
R'
R'
R'
(a)*,(b)
O
(c)
O
(d)
O
NO
NO
2
2
R''
2
R''
3
R''
1
8
10
9
OBn
OH
O
O
3
3
4
R'
NO
R'
5
R'
2
(g)
(e)
(f)
2
2
6
N
H
N
H
NO
2
7
R''
4
R''
5
R''
6
OH
H
N
2
4
5
*
O
O
1
3
7
O
R'
6
1a-7a: R'-H; R''-OCH
3
N
H
1b-7b: R'-OCH ; R''-H
3
R''
7
Fig. 2. Synthetic pathway: (a) fuming HNO3, AcOH, rt.; (*) two extra regioisomers of nitro derivative were obtained for 1a and 1b in para and meta positions to aldehyde group,
respectively, (b) BBr3, CH2Cl2, for 1a ꢀ40 ꢁC / rt., and ꢀ78 ꢁC for 1b; (c) benzyl chloride, K2CO3, KI, CH3CN; (d) CH3NO2, K2CO3, 18-crown-6 ether, 1,4-dioxane, 12 ꢁC / rt, then Ac2O,
NaOAc, 100 ꢁC; (e) H2, Pd/C, EtOH–AcOH; (f) (þ/ꢀ)-epichlorohydrin, w3% NaOH aq., 1,4-dioxane; (g) (2-methoxyphenoxy)ethylamine, CH3CN, 80 ꢁC.
decreased the systolic and diastolic blood pressures only in 30 and
10 min after administration, respectively. Both enantiomers of
compound 7b displayed similar hypotensive activity. These
compounds significantly decreased the systolic blood pressure in
the range of doses 0.125–1.0 mg kgꢀ1 and the diastolic blood
pressure in the doses 1.0 and 0.5 mg kgꢀ1 throughout the whole
observation period. In the lower doses the hypotensive activity
becomes weaker and disappeared in the doses 0.0625 and
0.0312 mg kgꢀ1, respectively for enantiomer R and enantiomer S of
compound 7b (Fig. 6).
compound 7a influenced on the frequency of contractions of iso-
lated rabbit small intestine.
Compound 7b, as a racemic mixture and both enantiomers, at
the highest dose 10ꢀ5 M statistically significantly decreased the
frequency, but only both enantiomers of compound 7b significantly
diminished the amplitude of contractions of isolated rabbit small
intestine (of about 21–22%). In the lower doses compound 7b had
no influence on the frequency and amplitude of contractions of
isolated rabbit small intestine.
4. Discussion
3.5. Influence on isolated rabbit ileum
The aim of our study was to evaluate the cardiovascular activity of
new compounds: 7a, (2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-
(2-methoxyphenoxy)ethylamino)propan-2-ol, and 7b, (2RS)-1-(5-
methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)
propan-2-ol as racemic mixtures and pairs of enantiomers. They are
methoxy derivatives of compound (RS)-9, the chemical structure
Compound 7a, as a racemic mixture and enantiomer S, only
given at doses 10ꢀ5 M and 10ꢀ6 M statistically significantly
decreased the amplitude of contractions of isolated rabbit small
intestine (of about 10–57%) but none of the tested doses of
of which is related to carvedilol, non-selective
b-antagonist with
a1-adrenolytic activity. Carvedilol has adjunctive pharmacologic
properties, including a1-blocking, antioxidant, anti-inflammatory
Fig. 4. ORTEP diagram of (2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-(2-methox-
yphenoxy)ethylamino)propan-2-ol (7a) with the hydrogens omitted for clarity.
Summary of data CCDC 290726.
Fig. 3. ORTEP diagram of 2-(benzyloxy)-3-methoxy-6-nitrobenzaldehyde (3b) with
the hydrogens omitted for clarity. Summary of data CCDC 295392.

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G. Groszek et al. / European Journal of Medicinal Chemistry 44 (2009) 5103–5111
Table 3
Table 1
Prophylactic antiarrhythmic activity in anesthetized rats.
Affinity for different adrenoceptor types in the rat cerebral cortex.
Compound
ED50 iv (mg kgꢀ1
)
Compound
[3H]Prazosin Ki
[nM] ꢂ SEM
[3H]Clonidine Ki
[nM] ꢂ SEM
[3H]CGP12177 Ki
[nM] ꢂ SEM
(RS)-7a
(R)-7a
(S)-7a
(RS)-7b
(R)-7b
(S)-7b
(RS)-9
Carvedilol
Propranolol
0.45 (0.11–1.74)
0.38 (0.10–1.46)
0.53 (0.26–1.10)
0.38 (0.24–0.60)
0.16 (0.06–0.37)
0.30 (0.16–0.57)
0.34 (0.23–0.51)
0.25 (0.12–0.53)
(RS)-7a
(R)-7a
(S)-7a
(RS)-7b
(R)-7b
(S)-7b
75.8 ꢂ 2.7
60.9 ꢂ 1.6
168.8 ꢂ 7.2
21.1 ꢂ 1.7
45.8 ꢂ 6.8
11.3 ꢂ 0.3
89.8 ꢂ 9.5
2.2 ꢂ 0.2a
180.8 ꢂ 3.7
108.8 ꢂ 2.3
277.2 ꢂ 13.2
56.9 ꢂ 0.7
43.0 ꢂ 1.8
60.9 ꢂ 0.2
125.0 ꢂ 5.2
530.6 ꢂ 24.8
59.3 ꢂ 5.8
1600 ꢂ 200
3400 ꢂ 600
886.7 ꢂ 46.9
3.0 ꢂ 0.6
(RS)-9
Carvedilol
1.4 ꢂ 0.4
3.4 ꢂ 0.9
m
m
M
M
1.05 (0.64–1.73)a
0.81 ꢂ 0.06a
a
a
Ref. [11].
Ref. [10].
The compound 7a as a racemic mixture and both enantiomers
had high affinity to adrenergic receptors in rat cerebral cortex.
antiendothelin, antiproliferative, and antiarrhythmic activities that
appear to underlie the outcomes demonstrated in experimental
models and clinical trials [12]. Compound (RS)-9 described in
Part 1 [8], possesses an antiarrhythmic and hypotensive activity
For
a-adrenoceptors (a1 and a2) there were no essential differ-
ences between enantiomers. The greatest discrepancy was
observed in affinity to b1-adrenoceptor. Enantiomer S had 10-fold
and
b- and a-adrenolytic mechanism of action.
greater affinity to b1-adrenoceptors than enantiomer
compound 7a.
Compound 7b did not display large differences (maximally four
times) in adrenoceptor affinity between enantiomers.
R of
Pharmacological properties of compounds 7a and 7b and their
enantiomers were investigated in comparison with carvedilol and
(RS)-9.
These results, especially in the case of compound 7a, give
evidence about the relationship of spatial configuration and affinity
Table 2
Effects of an iv injection of the investigated compounds in dose of 1 mg kgꢀ1 on
heart rate and ECG intervals in anesthetized male Wistar rats (60 mg of thiopental
kgꢀ1 ip).
to
adrenoceptors. The same results were observed for enantiomers of
carvedilol and other -adrenergic antagonists as well as enantio-
b-adrenoceptors and a lack of such a relationship in the case of a-
b
Compound Parameters Time of observation (min)
mers of (RS)-9, tested before [8,13].
0
1
5
15
The antiarrhythmic effects of the novel compounds were
examined on rats using the model of adrenaline-induced
arrhythmia. Compounds 7a and 7b and their enantiomers admin-
istrated iv 15 min before arrhythmogen, prevented or attenuated
the symptoms of adrenaline-induced arrhythmia. The antiar-
rhythmic activity of the tested compounds was similar, but slightly
weaker than that of carvedilol or compound (RS)-9. All tested
compounds were more active than propranolol in this test. Anti-
(RS)-7a
(R)-7a
(S)-7a
(RS)-7b
(R)-7b
(S)-7b
(RS)-9
P–Q (ms)
QRS (ms)
Q–T (ms)
Beats/min
54.4 ꢂ 2.0
22.0 ꢂ 1.0
85.8 ꢂ 2.5
58.8 ꢂ 0.9b
24.2 ꢂ 1.2
87.1 ꢂ 2.3
59.4 ꢂ 0.4c
23.0 ꢂ 0.8
79.2 ꢂ 3.4
57.3 ꢂ 1.1
22.7 ꢂ 0.5
79.2 ꢂ 3.1
332.0 ꢂ 7.4
297.3 ꢂ 4.5d 292.2 ꢂ 6.8d 300.0 ꢂ 7.6
P–Q (ms)
QRS (ms)
Q–T (ms)
Beats/min
54.8 ꢂ 1.3
23.2 ꢂ 0.5
87.2 ꢂ 2.8
292.3 ꢂ 7.6
58.5 ꢂ 1.4
22.7 ꢂ 0.5
89.2 ꢂ 2.3
267.4 ꢂ 9.7
59.7 ꢂ 2.8
23.3 ꢂ 0.6
88.0 ꢂ 2.2
58.0 ꢂ 2.2
24.5 ꢂ 0.8
81.7 ꢂ 2.7
259.0 ꢂ 9.8b 255.2 ꢂ 11.6b
arrhythmic activity of pure b-adrenergic blocking agents is known
P–Q (ms)
QRS (ms)
Q–T (ms)
Beats/min
51.2 ꢂ 2.2
22.4 ꢂ 0.6
81.2 ꢂ 3.4
58.5 ꢂ 2.1b
25.0 ꢂ 0.8a
78.8 ꢂ 5.4
56.7 ꢂ 2.4
24.5 ꢂ 0.8b
94.8 ꢂ 3.4
53.3 ꢂ 1.6
22.5 ꢂ 0.5
83.0 ꢂ 3.9
for years. Also, carvedilol possesses an antiarrhythmic effect. The
electrophysiological properties of carvedilol, and application in
antiarrhythmic therapy were described previously [7,8,14].
324.2 ꢂ 11.0 292.0 ꢂ 9.3b 292.3 ꢂ 8.5b 275.9 ꢂ 7.3d
Hypotensive activity of the investigated compounds was
determined after their iv administration to normotensive anes-
thetized rats. All forms of compound 7a diminished the systolic and
diastolic blood pressures throughout the whole observation period
at a range of doses 0.25–1.0 mg kgꢀ1. In the lower dose the hypo-
tensive effect disappeared. Each enantiomeric form of compound
7b displayed similar hypotensive effect. Compound 7b (R, S and RS)
decreased the systolic blood pressure in the range of doses 0.125–
1.0 mg kgꢀ1 and in a less extent, the diastolic blood pressure. The
hypotensive effect is probably due to adrenoceptor blockade (a1-in
arteries and b1-in heart). In radioligand binding studies we found
P–Q (ms)
QRS (ms)
Q–T (ms)
Beats/min
44.6 ꢂ 2.5
26.7 ꢂ 1.1
108.0 ꢂ 5.8
48.7 ꢂ 2.3
31.3 ꢂ 1.7a
111.4 ꢂ 6.5
51.3 ꢂ 1.3
27.3 ꢂ 1.3
107.3 ꢂ 6.5
48.0 ꢂ 2.7
26.0 ꢂ 1.3
118.0 ꢂ 5.9
396.7 ꢂ 16.6 376.3 ꢂ 13.8 372.9 ꢂ 15.3 364.7 ꢂ 13.8
P–Q (ms)
QRS (ms)
Q–T (ms)
Beats/min
41.3 ꢂ 1.7
23.3 ꢂ 1.1
104.7 ꢂ 2.3
412.3 ꢂ 5.8
45.3 ꢂ 1.3
28.0 ꢂ 1.3b
106.7 ꢂ 2.4
42.7 ꢂ 1.6
28.7 ꢂ 1.7c
106.0 ꢂ 1.9
42.0 ꢂ 1.3
28.7 ꢂ 0.8
113.3 ꢂ 1.8b
387 ꢂ 2.1c
395.5 ꢂ 4.5a 403.2 ꢂ 7.3
P–Q (ms)
QRS (ms)
Q–T (ms)
Beats/min
44.7 ꢂ 1.7
27.3 ꢂ 1.3
110.0 ꢂ 5.5
48.7 ꢂ 2.5
26.0 ꢂ 1.3
107.3 ꢂ 5.6
46.0 ꢂ 1.6
28.7 ꢂ 0.8
111.3 ꢂ 7.1
46.0 ꢂ 1.9
28.0 ꢂ 0.8
118. ꢂ 4.30
393.0 ꢂ 16.2 388.1 ꢂ 15.3 381.0 ꢂ 13.6 367.6 ꢂ 10.8
the difference only in affinity of enantiomers of compound 7a to b1
adrenoceptor. No difference in affinity of isomers of 7a to a1
-
-
P–Q (ms)
QRS (ms)
Q–T (ms)
Beats/min
45.7 ꢂ 2.0
26.4 ꢂ 1.3
72.6 ꢂ 1.7
304.9 ꢂ 8.9
47.2 ꢂ 1.6
28.4 ꢂ 1.2
69.2 ꢂ 1.1
298.7 ꢂ 7.2
48.1 ꢂ 2.4
24.9 ꢂ 1.3
69.0 ꢂ 1.6
294.5 ꢂ 7.7
46.2 ꢂ 1.7
26.9 ꢂ 1.1
72.8 ꢂ 1.3
287.3 ꢂ 7.9
adrenoreceptors was observed. In our research we did not find
essential differences in hypotensive activity between enantiomers
of compounds 7a and 7b after iv administration. In opposite to
carvedilol and (RS)-9, tested before [8], there was no relationship
between the spatial configuration and hypotensive activity.
In the experiment on isolated rabbit ileum, the compounds 7a
and 7b, only in the highest dose of 10ꢀ5 M influenced the amplitude
and/or frequency of isolated rabbit small intestine. Weak spasmo-
lytic activity of the tested compounds seems to confirm that
Carvedilol P–Q (ms)
QRS (ms)
50.0 ꢂ 3.2
21.2 ꢂ 0.8
72.0 ꢂ 3.1
50.0 ꢂ 3.2
22.0 ꢂ 0.6
74.4 ꢂ 2.8
55.0 ꢂ 5.5
22.8 ꢂ 1.0
68.0 ꢂ 3.7
54.6 ꢂ 3.0
23.2 ꢂ 0.8
74.0 ꢂ 2.4
Q–T (ms)
Beats/min
356.7 ꢂ 21.0 345.2 ꢂ 17.7 340.3 ꢂ 14.8 320.4 ꢂ 10.2
Values are the mean ꢂ SEM of 6 experiments. Statistical analyses were performed
using a one-way ANOVA test.
a
p < 0.05.
p < 0.02.
p < 0.01.
p < 0.001.
b
c
hypotensive activity is caused by
spasmolytic one.
a-adrenolytic activity, but not by
d

G. Groszek et al. / European Journal of Medicinal Chemistry 44 (2009) 5103–5111
5107
Time (min)
0
0
1
2
3
5
10
15
20
30
40
50
60
-5
-10
-15
-20
-25
****
***
****
****
***
***
***
****
***
***
***
***
****
****
***
***
***
***
***
***
***
***
****
***
****
****
****
****
****
***
****
(RS)-7a
(R)-7a
(S)-7a
****
****
Fig. 5. Changes in mean blood pressure after iv administration of compound 7a and its enantiomers in the dose of 0.25 mg kgꢀ1. Statistical analyses were performed using a one-
way ANOVA test: ***p < 0.01, ****p < 0.001.
Time (min)
0
0
1
2
3
5
10
15
20
30
40
50
60
-5
-10
-15
-20
-25
*
*
*
**
*
*
**
**
**
*
*
**
*
**
**
**
**
**
**
***
***
**
***
**
***
***
***
(RS)-7b
(R)-7b
(S)-7b
***
Fig. 6. Changes in mean blood pressure after iv administration of compound 7b and its enantiomers in the dose of 0.125 mg kgꢀ1. Statistical analyses were performed using a one-
way ANOVA test: *p < 0.05, **p < 0.002, ***p < 0.01.
5. Conclusion
6. Experimental protocol
The results of this study confirmed that (2RS)-1-(5-methoxy-
1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-
2-ol and (2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-(2-methox-
yphenoxy)ethylamino)propan-2-ol and their enantiomers possess
a1-, a2- and b1-adrenolytic, antiarrhythmic and hypotensive activ-
ities. The results suggest that the antiarrhythmic and hypotensive
effects of the compounds are related to their adrenolytic properties,
but the pharmacological effects of the tested compounds and their
enantiomers were qualitatively weaker than those of carvedilol and
(RS)-9. The introduction of the methoxy group in 5 or 7 position of
indole moiety of compound (RS)-9 attenuates the activity of the
tested compounds relative to compound (RS)-9.
6.1. Chemistry
6.1.1. General
Melting points were determined on a Boe¨tius apparatus and are
uncorrected or on DSC Mettler Toledo Instrument 822e. 1H and 13
C
NMR spectra were recorded on Bruker or Varian (500, 400 or
200 MHz) instruments. Chemical shifts are expressed in ppm (
d
)
referred to TMS, coupling constants (J) are in Hz. IR and UV spectra
were recorded on Perkin–Elmer and Hewlett Packard 8453
instruments, respectively. IR spectra were recorded in KBr pallets
and wavenumbers are expressed in cmꢀ1. Elemental analysis was
done on AE 1108 Carlo Erba apparatus. Mass spectra were obtained

5108
G. Groszek et al. / European Journal of Medicinal Chemistry 44 (2009) 5103–5111
on an AMD-604 or Mariner Spec spectrometers. The X-ray struc-
tures were determined on the ‘KappaCCD’ (Nonius) diffractometer.
Optical rotations were obtained on a Jasco P-1020 or P-2000
apparatus. TLC plates precoated with silica gel 60 F254 was used for
monitoring, and silica gel 230–400 mesh was used for flash column
chromatography (both from Merck).
1H, OH); 11.15 (s, 1H CHO). 13C NMR (125 MHz, CDCl3): 57.7 (OCH3);
111.3; 121.5; 123.3; 141.2; 143.5; 155.8; 191.9 (CHO). IR: 714.0;
733.6; 810.6; 835.5; 1179.2; 1285.4; 1363.6; 1472.1; 1528.9; 1662.5.
EIMS (70 eV) m/z [%]: 197 (Mþ, 100); 179 (Mþ-H2O, 7); 149 (33); 137
(18); 136 (17); 135 (27); 134 (44); 121 (80); 120 (19); 119 (15); 108
(47); 107 (41); 106 (43); 95 (11); 93 (30); 92 (31); 79 (39); 65 (80).
HRMS for C8H7NO5 (Mþ); calcd: 197.0324, found: 197.0327.
6.1.2. Materials
(þ/ꢀ)-1-Chloro-2,3-epoxypropane, was purchased from Aldrich
Chemicals; 99.9% of (S)-(þ) and 99.8% (R)-(ꢀ)-1-chloro-2,3-epox-
ypropane with optical purity 99.0% and 99.9% ee, respectively, were
provided by Chemos GmbH. Fuming nitric acid, d ¼ 1.52, 2,3-
dimethoxybenzaldehyde and 2,5-dimethoxybenzaldehyde, boron
tribromide solution 1.0 M in dichloromethane, were obtained from
Fluka Chemicals.
6.1.4. 6-(Benzyloxy)-3-methoxy-2-nitrobenzaldehyde (3a)
The compound 2a (5.65 g, 0.03 mol) was dissolved in acetoni-
trile (200 mL). Then potassium carbonate (4.1 g, 0.03 mol) was
added and stirred for 10 min in room temperature. Benzyl chloride
(6 mL, 6.6 g, 0.05 mol) and potassium iodide (50 mg) were added.
The reaction mixture was carried out under reflux for 2.5 h, (TLC
monitoring; hexane/ethyl acetate, 3:1). Cooled reaction mixture
was poured to water (1.75 L) and precipitate was filtered off in
vacuum and dried in the air. The product 3a was obtained as a fine
crystalline solid (7.65 g; 93%). The compound 3a was suitable for
upcoming transformation. For physical and spectral analyses the
product was recrystallized from dichloromethane/hexane, and
afforded pale yellow fine crystalline powder, m.p. 146–147 ꢁC. 1H
NMR (400 MHz, CDCl3): 3.85 (s, 3H, OCH3); 5.19 (s, 2H, OCH2Ph);
7.16 (d, J ¼ 9.35, 1H, ArH); 7.25 (d, J ¼ 9.35, ArH); 7.36–7.42 (m, 5H,
ArH); 10.42 (s, 1H, CHO). 13C NMR (100 MHz, CDCl3): 57.1 (OCH3);
71.8 (OCH2Ph); 115.9; 116.7; 119.9; 127.4 (2C); 128.7; 128.9 (2C);
135.2; 138.5; 144.7; 154.3; 186.0 (CHO). IR: 733.4; 813.8; 952.3;
1090.9; 1189.9; 1273.4; 1284.5; 1434.1; 1451.0; 1489.8; 1499.5;
1541.9; 1690.9. EIMS (70 eV) m/z [%]: 287 (Mþ, 2); 92 (8); 91 (100);
79 (1); 65 (6). HRMS for C15H13NO5 (Mþ); calcd: 287.0794, found:
287.0792.
Solvents were distilled and dried if required. Other common
materials were commercial products.
(2-Methoxyphenoxy)ethylamine was obtained according to
literature [15].
[3H]Prazosin, [3H]Clonidine and [3H]CGP12177 were supply by
Perkin–Elmer.
Reference compound, carvedilol, was submitted by Pharma-
ceutical Research Institute, Warsaw, Poland.
6.1.3. 6-Hydroxy-3-methoxy-2-nitrobenzaldehyde (2a)
2,5-Dimethoxybenzaldehyde, 1a, (20 g; 0.12 mol) was dissolved
in acetic acid (450 mL). Reaction mixture was cooled to 10 ꢁC
(water/ice), and then fuming nitric acid (95 mL; 144.4 g; 2.3 mol)
was added dropwise during 25 min while vigorously stirring.
Afterward reaction mixture was allowed to warm to room
temperature and kept for 45 min. The yellow suspension was
poured to mixture of water and crushed ice (2 L). The precipitate
was filtered off in vacuum and rinsed excessively with water and
dried in the air. The mixture of two compounds was obtained; 3,6-
6.1.5. 2-(Benzyloxy)-3-methoxy-6-nitrobenzaldehyde (3b)
Conversion of 2,3-dimethoxybenzaldehyde to derivative 3b was
performed according to procedure described in Sections 6.1.3 and
6.1.4. Nitration of 2,3-dimethoxybenzaldehyde afforded a mixture
of 5- and 6-nitro derivatives. They were separated by a cumber-
some nuisance chromatography on silica gel (100-fold more of
stationary phase to weight of product mixture; eluent: hexane/
ethyl acetate, 1:1). Intermediate 2,3-dimethoxy-5-nitro-
benzaldehyde was obtained with yield of 46%, m.p. 117–118 ꢁC
(EtOAc), and intermediate 2,3-dimethoxy-6-nitrobenzaldehyde
with yield of 36%, m.p. 107.5–109 ꢁC (EtOAc), lit. 108–109 ꢁC [18].
2,3-Dimethoxy-6-nitrobenzaldehyde was subjected to selective
monodemethylation, and afforded 2-hydroxy-3-methoxy-6-nitro-
benzaldehyde, 2b, with yield of 98%, m.p. 103–105.5 ꢁC (EtOAc/
hexane), lit. 92.5–93.5 ꢁC [19]. The latter was converted to product
3b with yield of 90%, m.p. 97–99 ꢁC (dichloromethane/hexane),
lit.108 ꢁC (benzene/petrol ether) [20]. 1H NMR (500 MHz, CDCl3):
4.00 (s, 3H, OCH3); 5.06 (s, 2H, OCH2Ph); 7.05 (d, J ¼ 9.2, 1H, ArH);
7.32–7.41 (m, 5H, ArH); 7.93 (d, J ¼ 9.2, ArH); 10.17 (s, 1H, CHO). 13C
NMR (125 MHz, CDCl3): 56.6 (OCH3); 76.8 (OCH2Ph); 112.6; 121.7;
128.5 (2C); 128.6; 128.8 (2C); 130.6; 136.0; 139.5; 145.7; 158.6; 188.4
(CHO). IR: 702.9; 751.7; 1076.9; 1215.0; 1237.0; 1271.8; 1327.6;
1337.6; 1477.7; 1510.9; 1575.1; 1713.3; 2876.5; 2966.6; 3106.7. UV
dimethoxy-2-nitrobenzaldehyde
and
2,5-dimethoxy-4-nitro-
benzaldehyde (detected by TLC). Part of compound 3,6-dimethoxy-
2-nitrobenzaldehyde was separated from reaction mixture via
crystallization from dichloromethane. Purification of the remaining
residue by flash chromatography on silica gel (300 g; eluent:
hexane/ethyl acetate, 1:1) furnished:
- 3,6-dimethoxy-2-nitrobenzaldehyde as orange crystals
(19.25 g; 76%); m.p. 171 ꢁC (DSC) (dichloromethane), m.p. lit.
171–172 ꢁC [16]. 1H NMR (200 MHz, CDCl3): 3.93 (s, 3H, OCH3);
4.02 (s, 3H, OCH3); 7.18 (d, J ¼ 9.4, 1H, ArH); 7.36 (d, J ¼ 9.4, 1H,
ArH); 10.43 (s, 1H, CHO). IR: 716.9; 826.1; 949.9; 1187.3; 1293.5;
1433.6; 1494.8; 1541.8; 1688.8 (C]O) and
- 2,5-dimethoxy-4-nitrobenzaldehyde was obtained as yellow
crystals (4.47 g, 18%), crystallized from ethyl acetate, m.p.
174.5–175.5 ꢁC, m.p. lit. 163–165 ꢁC (Ethanol) [17].
3,6-Dimethoxy-2-nitrobenzaldehyde (7.1 g; 0.034 mol) was
dissolved in dichloromethane (500 mL). The mixture was cooled to
ꢀ50 ꢁC (acetone/dry ice), then boron tribromide solution in
dichloromethane (1 M; 34 mL; 0.034 mol) was added dropwise.
The reaction mixture turned deep dark blue, and then allowed to
warm up to room temperature. After 2 h reaction was completed
(monitoring on TLC: toluene/methanol, 5:1). Water (400 mL) was
poured into to the reaction mixture and stirred for ca. 20 min. The
organic layer was separated and washed with water and brine, than
dried over anhydrous magnesium sulfate. After evaporating solvent
to dryness, crude product was obtained as a solid. Crystallization
from dichloromethane/hexane afforded phenol 2a as olive crystals
(5.65 g, 85%), m.p. 99.5–101 ꢁC. 1H NMR (500 MHz, CDCl3): 3.91 (s,
3H, OCH3); 7.14 (d, J ¼ 9.3,1H, ArH); 7.35 (d, J ¼ 9.3,1H, ArH); 9.84 (s,
(EtOH), (nm), lmax: 326 (
3
¼ 7500), (c ¼ 0.21 mg/10 mL). Crystal
data: C15H13NO5, MW 287.26, triclinic, P-1, Z ¼ 2, Calculated densi-
ty ¼ 1.437 Mg/m3, a ¼ 8.5710(3) Å, b ¼ 8.7110(2) Å, c ¼ 9.5770(4) Å,
a
¼ 82.678(2)ꢁ,
b
¼ 77.641(2)ꢁ,
g
¼ 72.264(2)ꢁ, V ¼ 663.78(4) Å3,
T ¼ 100(2) K, l[MoK ¼ 0.71073 Å, R1 ¼3.17%, wR1 ¼8.59%, crystal
a]
size 0.2 ꢃ 0.2 ꢃ 0.2 mm3, light green.
6.1.6. 1-(Benzyloxy)-4-methoxy-3-nitro-2-(2-nitrovinyl)benzene
(4a)
Potassium carbonate (3.8 g, 0.028 mol) was suspended in 1,4-
dioxane (100 mL). Then, nitromethane (7.5 mL; 8.48 g; 0.14 mol) was

G. Groszek et al. / European Journal of Medicinal Chemistry 44 (2009) 5103–5111
5109
added and stirred for 10 min at room temperature. The reaction
mixture was cooled to 12 ꢁC and kept for 1 h. Later, compound 3a
(3.94 g; 0.014 mol) was added followed by 18-crown-6 ether
(305 mg; 1.16 mmol). The progress of the reaction was monitored by
TLC (toluene/methanol, 9:1). After 24 h reaction was completed.
Solid from the reaction mixture was filtered off, and then acetic
anhydride (13 mL; 0.14 mol) was added to the filtrate followed by
sodium acetate (200 mg) and heated at 100 ꢁC. The progress of the
reaction was monitored by TLC (toluene/methanol, 9:1). After 2 h
reaction was completed, and then the reaction mixture was poured
into water with ice (1.5 L). The yellow precipitate was filtered off and
dried in the air. The crude product 4a was crystallized from
dichloromethane/hexane to yield yellow crystals (3.71 g; 82%), m.p.
158–161 ꢁC.1H NMR (500 MHz, CDCl3): 3.85 (s,1H, OCH3); 5.21 (s, 2H,
OCH2Ph); 7.12 (br s, 2H, ArH); 7.37–7.43 (m, 5H, ArH); 7.74 (d, J ¼ 13.5,
1H, ]CH); 7.91 (d, J ¼ 13.5, 1H, ]CH). 13C NMR (125 MHz, CDCl3):
57.0 (OCH3); 71.9 (OCH2Ph); 112.5; 115.0; 116.5; 127.2; 127.4 (2C);
128.8; 129.0 (2C); 134.9; 142.2; 142.4; 144.8; 151.7. IR: 802.2; 952.3;
962.3; 1027.3; 1035.2; 1275.0; 1287.4; 1336.6; 1517.7; 1539.3; 1635.3.
EIMS (70 eV) m/z [%]: 330 (Mþ, <1); 193 (3); 91 (100); 65 (7). HRMS
for C16H14N2O6 (Mþ); calcd: 330.0852, found: 330.0843.
chromatography on silica gel and crystallized from dichloro-
methane/hexane and afforded colorless crystals of indole 5b (yield
58%), m.p.152–154 ꢁC, lit. 129–132 ꢁC [9]. 1H NMR (500 MHz,
CDCl3): 3.91 (s, 3H, OCH3); 5.87 (s, 1H, OH); 6.62–6.64 (m, 1H, 3-H);
6.88 (dd, J ¼ 8.6 and 0.75, 1H, ArH); 6.91 (d, J ¼ 8.6, 1H, ArH); 7.13 (t,
J ¼ 2.8, 1H, 2-H); 7.99 (br s, 1H, NH). 13C NMR: 58.4 (OCH3); 99.4;
102.0; 109.7; 117.7; 124.2; 133.2; 138.5; 138.8.
6.1.10. 7-Methoxy-4-(oxiran-2-ylmethoxy)-1H-indole (6a) and
5-methoxy-4-(oxiran-2-yl methoxy)-1H-indole (6b)
Indole derivatives 5a and 5b were converted to epoxide deriv-
atives as described in literature [8,21]. The products 6a and 6b were
obtained as an amorphic solid with yield of 69% and 86%,
respectively.
Product 6a was recrystallized from acetone/hexane, m.p. 96–
98 ꢁC. 1H NMR (500 MHz, CDCl3): 2.78 (dd, J ¼ ꢀ5.0 and 2.7, 1H, 10-
H); 2.90 (dd, J ¼ ꢀ5.0 and 4.2, 1H, 10-H); 3.40–3.43 (m, 1H, 9-H);
3.90 (s, 1H, OCH3); 4.1 (dd, J ¼ ꢀ11.1 and 5.4, 1H, 8-H); 4.28 (dd,
J ¼ ꢀ11.1 and 3.4, 1H, 8-H); 6.4 (d, J ¼ 8.3, 1H, ArH); 6.48 (d, J ¼ 8.3,
1H, ArH); 6.64 (dd, J ¼ 3.1 and 2.3, 1H, 3-H); 7.09 (t, J ¼ 2.8, 1H, 2-H);
8.42 (br s, 1H, NH). 13C NMR (125 MHz, CDCl3): 44.9; 50.4; 55.6
(OCH3); 69.5; 100.4; 100.8; 101.4; 120.3; 122.6; 127.7; 141.5; 146.5.
IR: 717.7; 767.3; 1081.9; 1253.2; 1359.0; 1454.3; 1523.0; 3350.7.
Anal. for C12H13O3N [%]; calcd: C-65.74; H-5.98; N-6.39, found: C-
65.70; H-6.07; N-6.39.
Product 6b was recrystallized from ethyl acetate, m.p. 48–50 ꢁC.
1H NMR (500 MHz, CDCl3): 2.70 (dd, J ¼ ꢀ5.0 and 2.7, 1H, 10-H);
2.83–2.85 (m, 1H, 10-H); 3.38–3.41 (m, 1H, 9-H); 3.88 (s, 3H, OCH3);
4.18 (dd, J ¼ ꢀ11.5 and 5.9,1H, 8-H); 4.39 (dd, J ¼ ꢀ11.5 and 3.55, 1H,
8-H); 6.60–6.61 (m, 1H, 3-H); 6.90 (d, J ¼ 8.7, 1H, ArH); 7.04 (d,
J ¼ 8.7, 1H, ArH); 7.10 (t, J ¼ 2.8, 1H, 2-H); 8.29 (br s, 1H, NH). 13C
NMR (125 MHz, CDCl3): 44.8; 50.8; 58.3 (OCH3); 73.9; 99.5; 106.6;
111.6; 123.0; 125.0; 133.1; 140.5; 144.8. IR: 733.5; 1023.0; 1040.3;
1091.4; 1212.1; 1238.6; 1330.8; 1354.1; 1492.8; 1579.2; 2830.8;
6.1.7. 2-(Benzyloxy)-1-methoxy-4-nitro-3-(2-nitrovinyl)benzene
(4b)
The compound 4b was obtained as described in Section 6.1.6.
The crude product 4b was crystallized from EtOAc/hexane, and
afforded red-orange crystalline solid of compound 4b (87%), m.p.
118–120 ꢁC, lit. 119–120 ꢁC (Methanol) [20]. 1H NMR (500 MHz,
CDCl3): 4.04 (s, 3H, OCH3); 5.03 (s, 2H, OCH2Ph); 7.07 (d, J ¼ 9.2, 1H,
ArH); 7.27–7.28 (m, 2H, ArH); 7.34–7.35 (m, 3H, ArH); 7.47 (d,
J ¼ 13.6, 1H, ]CH); 7.95 (d, J ¼ 13.6, 1H, ]CH); 7.97 (d, J ¼ 9.2, 1H,
ArH). 13C NMR (125 MHz, CDCl3): 56.6 (OCH3); 75.8 (OCH2Ph);
112.3; 121.7; 122.6; 128.7 (2C); 128.8 (2C); 129.0; 130.0; 135.5;
141.9; 142.3; 146.3; 157.5. IR: 747.6; 953.5; 1085.5; 1277.9; 1343.1;
1465.0; 1519.9; 1570.5; 1641.8; 2944.8; 3092.4. UV (CH3CN), (nm),
2931.6; 3326.0. UV (EtOH), (nm), lmax: 271 (
10 mL). Anal. for C12H13NO3 [%]; calcd: C-65.74; H-5.98; N-6.39,
found: C-65.73; H-5.88; N-6.41.
3
¼ 7400), (c ¼ 0.28 mg/
lmax: 278 (
3
¼ 13,700), (c ¼ 0.17 mg/10 cm3).
6.1.8. 7-Methoxy-1H-indol-4-ol (5a)
The compound 4a (4.1 g, 0.012 mol) was suspended in a mixture
of ethanol (110 mL) and acetic acid (13 mL) and stirred with Pd/C
(10%, 0.33 g) under an atmosphere of hydrogen (1 bar) at room
temperature for 8 h. The progress of the reaction was monitored by
TLC (hexane/acetone, 4:1). The catalyst was collected by filtration
through Celite 545, and washed with dichloromethane (200 mL).
Water (100 mL) was added to the filtrate and neutralized with
saturated solution of sodium bicarbonate. The organic layer was
separated and washed with water. Then, organic layer was dried
over anhydrous sodium sulfate and solvent was evaporated to
dryness. The crude product, oil, was purified by column chroma-
tography on silica gel (20 g, eluent: hexane/acetone, 4:1).
Compound 5a was obtained as a pale pink solid (1.63 g, 80%), later
was recrystallized from dichloromethane/petroleum ether, and
afforded colorless fine crystals, m.p. 121.5–124 ꢁC. 1H NMR
(500 MHz, acetone-d6): 3.84 (s, 1H, OCH3); 6.32 (d, J ¼ 8.1, 1H, ArH);
6.43 (d, J ¼ 8.1, 1H, ArH); 6.56 (t, J ¼ 2.6, 1H, 3-H); 7.15 (t, J ¼ 2.6, 1H,
2-H); 7.77 (s, 1H, OH); 10.1 (br s, 1H, NH). 13C NMR (125 MHz,
acetone-d6): 55.9 (OCH3); 100.2; 102.8; 103.0; 120.7; 123.5; 129.0;
141.3; 145.5. IR: 729.0; 1024.0; 1072.7; 1086.8; 1262.0; 1453.1;
1497.0; 1521.8; 3229.7; 3420.5. EIMS (70 eV) m/z [%]: 163 (Mþ,100);
148 (82); 120 (19); 92 (11); 91 (3); 65 (7). HRMS for C9H9NO2 (Mþ);
calcd: 163.0633, found: 163.0641.
6.1.11. (2RS)-1-(7-Methoxy-1H-indol-4-yloxy)-3-(2-(2-
methoxyphenoxy)ethylamino)propan-2-ol ((RS)-7a) and (2RS)-1-
(5-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)
ethylamino)propan-2-ol ((RS)-7b)
The compounds 6a and 6b were converted to final products 7a
and 7b as described in literature [8].
The compound (RS)-7a was obtained as a solid (yield 46%). Crys-
tallization from acetone afforded colorless crystals, m.p. 133–133.5 ꢁC.
1H NMR (500 MHz, acetone-d6): 2.74 (br s, 2H, OH and NH aliph.); 2.85
(dd, J ¼ ꢀ12.0 and 6.7, 1H, 4-H); 2.97 (dd, J ¼ ꢀ12.0 and 4.1, 1H, 4-H);
3.01 (m, 2H, 3-H); 3.78 (s, 3H, OCH3); 3.86 (s, 3H, OCH3); 4.05–4.10 (m,
5H,1,2,5-H); 6.39 (d, J ¼ 8.2,1H, ArH); 6.49 (d, J ¼ 8.2,1H, ArH); 6.53 (dd,
J ¼ 3.0 and 2.2, 7-H); 6.84–6.91 (m, 2H, ArH); 6.94 (dd, J ¼ 7.7 and 1.9,
ArH); 6.97 (dd, J ¼ 7.7 and 1.9, 1H, ArH); 7.16 (m,1H, 6-H); 10.19 (br s,1H,
NH). 13C NMR (125 MHz, acetone-d6): 49.8; 53.4; 55.9 (OCH3); 56.2
(OCH3); 69.9; 70.0; 72.1; 100.5; 100.7; 102.1; 113.4; 115.4; 121.6; 121.7;
122.2; 123.7; 128.7; 142.4; 147.9; 149.8; 151.1. IR: 750.4; 783.6; 1090.7;
1104.4; 1262.7; 1503.0; 1523.7; 1595.8; 3320.1. EIMS (70 eV) m/z [%]:
386(Mþ, 37); 225(12);224(85); 180(28); 164(12); 163(100); 162(15.);
148 (19); 100 (15); 91 (2); 86 (12); 65 (2); 56 (28); 44 (22). HRMS for
C21H26N2O5 (Mþ): calcd 386.1842, found 386.1847. Crystal data:
C21H26N2O5, MW 385.24, orthorhombic, Pccn, Z ¼ 8, Calculated densi-
ty ¼ 1.309 Mg/m3,
a ¼ 12.6350(3) Å,
b ¼ 33.5010(6) Å,
c ¼ 9.2360(15) Å, V ¼ 3909.5(6) Å3, T ¼ 100(2) K, l[MoK ¼ 0.71073 Å,
a
]
6.1.9. 5-Methoxy-1H-indol-4-ol (5b)
Indole derivative 5b was obtained as described in Section 6.1.8.
After work-up the crude product was purified by column
R1 ¼3.94%, wR1 ¼9.98%, crystal size ¼ 0.1 ꢃ0.1 ꢃ0.2 mm3, colorless.
The compound (RS)-7b was obtained chromatographically pure
as a lightly brown oil (yield 77%). 1H NMR (500 MHz, CDCl3): 2.82

5110
G. Groszek et al. / European Journal of Medicinal Chemistry 44 (2009) 5103–5111
(m, 2H, 4-H); 3.02 (t, J ¼ 5.4, 2H, 5-H); 3.80 (s, 3H, OCH3); 3.85 (s,
3H, OCH3); 4.03–4.04 (m, 1H, 2-H); 4.08–4.14 (m, 3H, 1,3-H); 4.27
(dd, J ¼ ꢀ10.4 and 3.5,1H,1-H); 6.52 (br s,1H, 7-H); 6.85 (d, J ¼ 8.75,
1H, ArH); 6.85–6.88 (m, 4H, ArH); 7.02 (d, J ¼ 8.75, 1H. ArH); 7.08 (t,
J ¼ 2.7, 1H, 6-H); 8.79 (br s, 1H, NH). 13C NMR (125 MHz, CDCl3):
48.8; 51.6; 55.8 (OCH3); 58.2 (OCH3); 68.7; 69.2; 76.1; 99.2; 106.7;
110.9; 111.9; 114.1; 120.9; 121.5; 122.7; 125.1; 133.4; 140.3; 144.6;
148.3; 149.7. IR (film): 735.8; 1024.0; 1082.6; 1122.9; 1217.3;
1248.6; 1331.1; 1453.4; 1503.6; 1591.8; 2927.1; 3309.4, 3350.3.
HRMS (ESIþ) for C21H27N2O5 ([M þ H]þ); calcd: 387.1915, found:
387.1917.
a mobile phase a mixture of ethanol and hexane with an addition of
0.1% of ammonium acetate and pumped through the system at
a flow rate of 1 mL minꢀ1. The retention times of (R)-7a and (S)-7a
were 6.6 min, and 8.5 min, respectively. The studied isomers were
well resolved and the ratio of their peak areas was used to estimate
the enantiomeric purity. On the basis of the results obtained, a final
purity of the selected enantiomers was 99.0% and 99.9% ee
respectively.
Finally, in the case of enantiomers (S)-7b and (R)-7b their
separation was done on the chiral stationary reversed phase,
cellulose tris(3,5-dimethylphenylcarbamate) Chiralcel OD-RH
column (5
m
m, 150 ꢃ 4.6 mm, Daicel Chemical Industry, Tokyo,
6.1.12. (2S)-1-(7-Methoxy-1H-indol-4-yloxy)-3-(2-(2-
Japan). The mobile phase consisted of methanol with an addition of
0.1% of ammonium acetate was pumped through the system at
a flow rate of 1 mL minꢀ1. The retention times of (R)-7b and (S)-7b
were 3.7 min, and 4.3 min, respectively. The separation of the
selected compounds gives enantiomers with a final purity of 99.0%
and 99.9% ee respectively.
methoxyphenoxy)ethylamino)propan-2-ol ((S)-7a) and (2S)-1-(5-
methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)
propan-2-ol ((S)-7b)
(S)-(þ)-4-(2,3-Epoxypropoxy)-1H-indole derivatives of 6 were
obtained as described in Section 6.1.10 using (R)-(ꢀ)-1-chloro-2,3-
epoxypropane in lieu of racemic mixture. For intermediate (S)-6a
the yield was 76%, and product was obtained chromatographically
pure as oil. Indole derivative (S)-6a was submitted to addition
reaction with (2-methoxyphenoxy)ethylamine as described for
compound (RS)-7 in Section 6.1.11, and furnished product (S)-7a as
6.2. Pharmacology
6.2.1. Animals
The experiment was carried out on male Wistar rats (180–250 g)
and male rabbits (2.5–3.0 kg). The animals were housed in constant
temperature facilities exposed to 12:12 light–dark cycle and
maintained on a standard pellet diet and tap water was given ad
libitum. Control and experimental groups consisted of 6–8 animals
each. The investigated compounds were administered intrave-
nously at a constant volume of 1.0 mL kgꢀ1. Control animals
received the equivalent volume of solvent.
a solid with yield of 77%, m.p. 97–98 ꢁC (dichloromethane),
25
[
a]
¼ ꢀ4.3ꢁ (c ¼ 1.005 in MeOH).
D
Compound (S)-6b was obtained with yield of 82%, as colorless
crystalline solid m.p. 60–61 ꢁC (EtOAc), [
CHCl3). In contrast to (S)-7a, derivative (S)-7b was obtained as
25
a
]
¼ þ11.25ꢁ (c ¼ 1.03 in
D
sensitive to moisture oil, with yield of 82%.
6.1.13. (2R)-1-(7-Methoxy-1H-indol-4-yloxy)-3-(2-(2-
methoxyphenoxy)ethylamino)propan-2-ol ((R)-7a) and (2R)-1-(5-
methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)
All procedures were conducted according to guidelines of ICLAS
(International Council on Laboratory Animals Science) and
approved by The Local Ethic Committee on Animal
Experimentation.
ethylamino)propan-2-ol ((R)-7b)
(R)-(ꢀ)-4-(2,3-Epoxypropoxy)-1H-indole derivatives of 6 were
obtained as described in Section 6.1.10 using (S)-(þ)-1-chloro-2,3-
epoxypropane in lieu of racemic mixture. For intermediate (R)-6a
the yield was 77%, and the form of product was chromatographi-
cally pure oil. Indole derivative (R)-6a was submitted to addition
reaction with (2-methoxyphenoxy)ethylamine as described for
compound (RS)-7 in Section 6.1.11, and furnished product (R)-7a as
6.2.2. Reference compound
Carvedilol was used as a reference drug.
6.2.3. Statistical analysis
Data are expressed as the mean ꢂ SEM. The statistical signifi-
cance was calculated using a one-way ANOVA. Differences were
considered significant when p < 0.05.
a solid with yield of 62%, m.p. 96–97 ꢁC (dichloromethane),
25
[
a]
¼ þ4.6ꢁ (c ¼ 1.01 in MeOH).
D
Compound (R)-6b was obtained with yield of 78%, as colorless
crystalline solid m.p. 59.5–60.5 ꢁC (EtOAc), [
in CHCl3). In contrast to (R)-7a, derivative (R)-7b was obtained with
6.2.4. Adrenoceptor radioligand binding assay
25
a
]
¼ ꢀ10.36ꢁ (c ¼ 1.15
The experiment was carried out on rat cerebral cortex. [3H]Pra-
zosin (19.5 Ci mmolꢀ1, an a1-adrenergic receptor), [3H]Clonidine
(70.5 Ci mmolꢀ1, an a2-adrenergic receptor) and [3H]CGP12177
(48 Ci mmolꢀ1 an b1-adrenergic receptor) were used. The brains
were homogenised in 20 vol of an ice-cold 50 mM Tris–HCl buffer
(pH 7.6) and were centrifuged at 20,000 ꢃ g for 20 min (0–4 ꢁC). The
cell pellet was resuspended in the Tris–HCl buffer and centrifuged
again. Radioligand binding assays were performed in plates
(MultiScreen/Millipore). The final incubation mixture (final volume
D
yield of 82% as foam sensitive to moisture.
6.1.14. Enantiomeric purity of (S)-7a,b and (R)-7a,b
Enantiomeric purity of (S)-7a and (R)-7a, and (R)-7b and (S)-7b
was assessed using liquid chromatography tandem mass spec-
trometry (ESI-LC/MS/MS) method equipped with an electrospray
ionization interface. Mass spectrometric detection was achieved by
an Applied Biosystems MDS Sciex API 2000 triple quadrupole mass
spectrometer (Concord, Ontario, Canada). The instrument was
coupled to an Agilent 1100 (Agilent Technologies, Waldbronn,
Germany) LC system. The MS/MS detector was operated at unit
resolution in the multiple reactions monitoring mode (MRM),
monitoring the transition of the protonated molecular ions to the
product ions m/z: 387.3 / 224.3 and 387.4 / 180.3 for (RS)-7a and
(RS)-7b, respectively.
300
[3H]Prazosin (0.2 nM), [3H]Clonidine (2 nM) or [3H]CGP12177
(0.2 nM) solution and 30 L of the buffer containing seven to eight
concentrations (10ꢀ11–10ꢀ4 M) of the tested compounds. For
measuring the unspecific binding, phentolamine,10 M (in the case
of [3H]Prazosin), [3H]Clonidine, 10 M (in the case of [3H]Clonidine)
and propranolol, 1
M (in the case of [3H]CGP12177) were applied.
mL) consisted of 240 mL of the membrane suspension, 30 mL of
m
m
m
m
The incubation was terminated by rapid filtration over glass fibre
filters (Whatman GF/C) using a vacuum manifold (Millipore). The
filters were then washed twice with the assay buffer and placed in
scintillation vials with a liquid scintillation cocktail. Radioactivity
was measured in a WALLAC 1409 DSA liquid scintillation counter. All
The separation of the enantiomers of (S)-7a and (R)-7a was
carried out on a normal phase an amylose tris(3,5-dimethylphe-
nylcarbamate) Chiralpak AD column (10
Chemical Industry, Tokyo, Japan) with a gradient elution, using as
m
m, 250 ꢃ 4.6 mm, Daicel

G. Groszek et al. / European Journal of Medicinal Chemistry 44 (2009) 5103–5111
5111
the assays were made in duplicate. The radioligand binding data
Acknowledgements
were analyzed using an iterative curve-fitting routine (GraphPAD/
Prism, Version 3.0, San Diego, CA, USA). Ki values were calculated
from the Cheng and Prusoff equation [22].
This project was supported by Polish Ministry of Scientific
Research and Information Technologies, Grant no. 2 P05F 010 28.
6.2.5. Effect on normal electrocardiogram (ECG)
Electrocardiographic measurement was carried out using the
Ascard B5 Eco apparatus, standard lead II, and paper speed
50 mm sꢀ1. The tested compounds were administered intrave-
nously in a dose of 1.0 mg kgꢀ1. The ECG recording was carried out
immediately before and 1, 5 and 15 min after administration of the
tested compounds. The effect of the compounds on rat ECG
recording was calculated according to Cambridge et al. [23].
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