Synthesis and specific nootropic activity of (-)-cytisine derivatives with carbamide and thiocarbamide moieties in their structure

Article abstract of DOI:10.1007/s10600-012-0329-7

N-(methylcytisinyl)-N-substituted ureas, N-substituted cytisine-12- carbamides, and cytisine-12- thiocarbamide were prepared by reaction of (-)-cytisine with urea and thiourea and of (-)-cytisine and its 12-N-methyl-3-amino derivative with isocyanates. Their specific nootropic activity was studied in vivo. The therapeutic index was determined for the lead compound. Promising candidates for further pharmacological testing were found.

Full text of DOI:10.1007/s10600-012-0329-7

Chemistry of Natural Compounds, Vol. 48, No. 4, September, 2012 [Russian original No. 4, July–August, 2012]
SYNTHESIS AND SPECIFIC NOOTROPIC ACTIVITY OF (–)-CYTISINE
DERIVATIVES WITH CARBAMIDE AND THIOCARBAMIDE
MOIETIES IN THEIR STRUCTURE
1*
1
1
1
I. P. Tsypysheva, A. V. Kovalꢀskaya, N. S. Makara, A. N. Lobov,
UDC 547.94:834.2
1
1
1
1,2
I. A. Petrenko, E. G. Galkin, T. A. Sapozhnikova, F. S. Zarudii,
and M. S. Yunusov
1
N-(methylcytisinyl)-Nꢀ-substituted ureas, N-substituted cytisine-12-carbamides, and cytisine-12-
thiocarbamide were prepared by reaction of (–)-cytisine with urea and thiourea and of (–)-cytisine and its
12-N-methyl-3-amino derivative with isocyanates. Their specific nootropic activity was studied in vivo.
The therapeutic index was determined for the lead compound. Promising candidates for further
pharmacological testing were found.
Keywords: (–)-cytisine, nootropic drugs, nicotinic acetylcholine receptor.
Recent research results [1, 2] suggest that disruption of cognitive functions is currently one of the most serious
medical problems in addition to cardiovascular and oncological diseases. The common prevalence of cognitive disorders
increases considerably the significance of medical therapy that is constantly required by patients for treating the disease itself
and accompanying pathologies and for adjusting the emotional status.
One component of combined therapy of cognitive dysfunction is represented by nootropic drugs [3–5] that are indicated
for vascular diseases of the brain, ischemias, chronic cerebrovascular insufficiency (including vascular dementia), skull–brain
injuries, neurodegenerative brain infections, Alzheimer’s disease, disruptions of brain function caused by alcoholism, and
acute neural infections.
O
O
N
N
H
N
H
N
6
R
N
N
N
N
6
O
O
O
N
R
N
+
N
N
H
R
c
O
7a
8
7a
7b
O
d, e
N
11
9
b
12
5
7a, 7b: R = NO
8: R = NH
7
2
2
f
4, 5
NH
O
8
13
4: R = Allyl
5: R = Ph
3
N
b
1
X
a
O
1
N
N
NH
2
O
N
N
R
HN
N
H
2: X = O
3: X = S
9: R = Allyl
10:R = Ph
2, 3
9, 10
O
O
a. (NH ) CO, toluene, 110ꢁC for 2; and (NH ) CS, pentanol, 137ꢁC for 3; b. PhNCO or AllylNCO, benzene, 20ꢁC; c. ONC(CH ) CNO,
2 2
2 2
2 6
benzene, 80ꢁC; d. MeI, K CO , acetone, 56ꢁC; e. HNO , H SO , 20ꢁC; f. H , Pd/C, MeOH, 20ꢁC
2
3
3
2
4
2
Scheme 1
1) Institute of Organic Chemistry, Ufa Scientific Center, RussianAcademy of Sciences, 450054, Ufa, Prosp. Oktyabrya,
71, e-mail: tsipisheva@anrb.ru; 2) Bashkir State Medical University, Ufa, Russia. Translated from Khimiya Prirodnykh
Soedinenii, No. 4, July–August, 2012, pp. 565–570. Original article submitted January 27, 2012.
©
0009-3130/12/4804-0629 2012 Springer Science+Business Media, Inc.
629

TABLE 1. Nootropic Activity of 1–6 and 8–10 at a Dose of 50 ꢂmol/kg and Therapeutic Index of Lead Drug 5
Compound
Mnestic activity, %
LD50, mg/kg
ED50, mg/kg
LD50/ED50
Control
–
71.7
6.1
–
–
400
–
–
–
–
26.5
–
–
–
Piracetama
10600
–
–
–
1
2
3
4
5
6
8
9
30.8
42.7
71.6
92.6
75.2
51.8
42.4
74.0
3500
11.7
299.1
–
–
–
–
–
–
–
–
–
–
–
–
10
______
a
Dose of 400 mg/kg.
Ligands of the nicotinic acetylcholine receptor (nACR) of natural origin, including the quinolizidine alkaloid
(–)-cytisine are positioned as a new group of effective agents for treating cognitive disorders [6–8]. Numerous derivatives of
it involving alkylation and acylation of the secondary N atom and functionalization of the 2-pyridone core were synthesized
during the last decade [9–17]. The activities of (–)-cytisine itself and compounds prepared from it were tested against the
nACR both in vitro and in vivo [9–18]. However, the neuropharmacological activity of (–)-cytisine derivatives with substituted
urea moieties of various structures is insufficiently studied.
We synthesized N-(methylcytisinyl)-Nꢀ-substituted ureas, N-substituted cytisine-12-carbamides, and cytisine-12-
thiocarbamide (Scheme 1) in order to discover among derivatives of the quinolizidine alkaloid (–)-cytisine compounds with
nootropic activity based on their potential choline-positive action and to establish the structure–activity relationship.
Products 2 and 3 were obtained by refluxing (–)-cytisine (1) with urea in toluene and thiourea in amyl alcohol,
respectively, in yields of 92 and 98%. Allyl-derivative 4 and phenyl-derivative 5 were synthesized by the isocyanate method
in quantitative yields [19]. Bimolecular product 6 was obtained by refluxing 1 in benzene with hexamethylene-1,6-diisocyanate
in 68% yield.
The problem of introducing the urea moiety into the cytisine pyridone core was solved in stages. First, 1 was converted
to the 12-N-methyl derivative [9], which was then nitrated by a mixture of conc. HNO and H SO [16]. The yields of 3-nitro-
3
2
4
and 5-nitro- regioisomers 7a and 7b, which were separated by column chromatography over SiO , were 70 and 10%, respectively.
2
Catalytic hydrogenation of 3-nitro product 7a over Pd catalyst [16] gave amine 8 in >98% yield. Subsequent reaction of 8
with allyl- and phenylisocyanate under conditions analogous to those for preparing 4 and 5 produced ureas 9 and 10. The
structures of the prepared compounds were confirmed by NMR spectroscopy, GC–MS, and comparison of physicochemical
constants with the literature.
Specific nootropic activity of 2–6 and 8–10 was studied using the basic model of passive avoidance conditioned
response (PACR) [20]. The reference drugs were piracetam and starting 1. Table 1 presents the test results.
According to the results, 1 at the studied dose, in contrast with its derivatives 2–6 and 8–10 did not exhibit noticeable
nootropic properties (Table 1). The mnestic activity of 1 expressed in percent was 6.1%. Replacing the O in 2 by S affected
insignificantly the mnestic activity. It increased for thioamide 3 from 30.8 to 42.7%. The indices for amine 8 and allylurea 9
also turned out to be low (51.8 and 42.4%). The mnestic activities of 4, 6, and 10 were comparable with that of the reference
piracetam and were 71.6, 75.2, and 74.0%, respectively. The index increased to 92.6% for 5.
The median effective dose (ED ), which was 11.7 mg/kg, and lethal dose (LD ), 3500 mg/kg, were determined for
50
50
the most promising candidate 5. The therapeutic index of this compound that was calculated as the LD /ED ratio was
50
50
significantly higher than that of piracetam and reached 299.1 vs. 26.5.
Thus, the reaction of 1 with urea and thiourea in addition to 1 and its 12-N-methyl-3-amino derivative with isocyanates
produced N-(methylcytisinyl)-Nꢀ-substituted ureas 9 and 10; N-substituted cytisine-12-carbamides 4–6, and cytisine-12-thio-
and –carbamide 2 and 3.
Specific nootropic activities of the resulting derivatives were studied in vivo using a basic model of PACR. The
therapeutic index of the lead compound was established. Promising candidates for further pharmacological testing were
found.
630

EXPERIMENTAL
Commercially available (–)-cytisine (CAS 485-35-8), allylisocyanate (CAS 1476-23-9), phenylisocyanate (CAS
103-71-9), urea (CAS 57-13-6), thiourea (CAS 62-56-6), H SO (98%, CAS 8014-95-7), HNO (CAS 7697-37-2), Pd/C
2
4
3
(10%, CAS 12135-22-7) were used as starting materials. N-Methylcytisine was prepared according to the literature [9]. The
/
course of reactions was monitored by TLC on Alugram plates with an aluminum backing coated by a layer (0.2 mm) of
standard silica gel 60 (Macherey-Nagel, Germany). Column chromatography (CC) was performed over standard silica gel 60
(0.05–0.1 mm) (Macherey-Nagel, Germany). Melting points of crystalline compounds were determined on a Boetius apparatus
(PHMK 05 VEB Wagetechnik Rapido, Radebeul). Optical rotation angles were measured on a PerkinElmer 341LC polarimeter
(Na lamp, wavelength 589 nm). High-resolution mass spectra were recorded in a Thermo Finnigan MAT95XP instrument (EI,
70 eV).
13
PMR and
C NMR spectra were recorded on Bruker Avance III pulsed spectrometers at operating frequency
1
13
500.13 MHz ( H) and 125.47 MHz ( C) using a 5-millimeter probe with a Z-gradient PABBO at constant sample temperature
298 K. Chemical shifts in PMR and C NMR spectra are given in ppm relative to TMS internal standard. 2D H– H COSY
13
1
1
spectra [21] were recorded in standard modes of multi-pulse sequences using the instrument software.
Specific nootropic activity was studied according to the literature [20] using a basic model of PACR. The experiments
were performed on Wistar white rats (180–200 g). Tested compounds and 1 were administered perorally at a dose of
50 ꢂmol/kg; piracetam, at a dose of 400 mg/kg. Distilled H O (control) was given 1 h before training in equal volumes. The
2
test was carried out in two stages, training the routine and reproducing its retention. On the first day of the experiment, the
following parameters were noted. The number of passes into the dark section was a parameter reflecting the training of the
animals (the fewer the passes, the faster the training process). The latent period of the first pass was compared with the
analogous parameter after training. Reproduction of the PACR routine was tested 24 h after training. The latent period of
the first pass, the number of passes into the dark section, and the total time located in the dark section were recorded [22].
Mnestic activity (M ) (improvement of memory under the influence of the tested compounds) was calculated using the formula
t
M = (t – t )/t ·100%, where M was the mnestic activity (%), t , the average residence time of the control animals in the dark
t
k
d
k
t
k
section; and t , the average residence time in the dark section of animals given the test compound [23].
d
Acute toxicity was determined using laboratory white mice (18–22 g) without taking into account the sex for a single
administration into the stomach at doses of 100, 200, 1000, 2000, 3000, 4000, and 5000 mg/kg. Animals were observed
during the acute toxicity test. The times of death, the number of deceased animals, and the clinical display of intoxication were
evaluated for 14 d. Acute toxicity parameters were calculated using the Litchfield–Wilcoxon method [24].
Cytisine-12-carbamide (2). A mixture of 1 (1 g, 5.2 mmol) and urea (0.63 g, 10.5 mmol) in toluene was refluxed
until 1 disappeared completely (TLC monitoring) and concentrated at reduced pressure. The solid was chromatographed over
20
SiO with elution by EtOH:MeOH (9:1) to afford 2 (1.1 g, 92%), mp 203–205°C, [ꢃ] –256.0° (MeOH), HR-MS (EI, m/z):
2
D
+
calcd for C H N O , 233.1159 [M] ; found, 233.1160.
12 15
3 2
PMR spectrum (CDCl , ꢄ, ppm, J/Hz): 2.02 (1H, m, H -8); 2.03 (1H, m, H -8); 2.50 (1H, m, H-9); 3.11 (1H, ddd,
3
anti
syn
2
3
4
2
3
J = 13.0, J
3.86 (1H, ddd, J = 15.6,
= 2.5, J
= 1.3, H -11); 3.13 (1H, dd, J = 12.4, J
= 2.1, H -13); 3.17 (1H, m, H-7);
11exo-9
2
11exo-10exo
exo
13exo-7 exo
3
4
2
3
J
= 6.5,
J
= 1.3, H -10); 4.07 (1H, ddt, J = 12.4,
J = 4.2,
13endo-7
10exo-9
10exo-11exo
exo
4
4
2
3
4
J
= 1.9, J
= 1.9, H
-13); 4.13 (1H, dt, J = 15.6, J
= 0.8, J
= 0.8, H
-10); 4.15
13endo-11endo
2
13endo-8syn
endo
10endo-9
10endo-8anti
endo
4
3
4
4
3
(1H, ddt, J = 13.0, J
= 3.8, J
= 1.9, J
= 1.9, H
-11); 6.34 (1H, dd, J = 7.0, J = 1.3,
11endo-9
11endo-8syn
11endo-13endo
3
endo
5-4
5-3
3
4
3
H-5); 6.41 (1H, dd, J = 8.9, J = 1.3, H-3); 7.45 (1H, dd, J = 8.9, J = 7.0, H-4).
3-4
3-5
4-3
4-5
13
C NMR spectrum (CDCl , ꢄ, ppm): 26.37 (C-8); 28.88 (C-9); 35.95 (C-7); 50.62 (C-10); 51.15 (C-11); 52.00
3
(C-13); 108.54 (C-5); 117.12 (C-3); 141.38 (C-4); 151.52 (C-6); 161.01 (C-14); 165.56 (C-2).
Cytisine-12-thiocarbamide (3). A mixture of 1 (1 g, 5.2 mmol) and thiourea (0.79 g, 10.5 mmol) in amyl alcohol
was refluxed until 1 disappeared completely (TLC monitoring). The resulting crystalline precipitate was filtered off to afford
20
+
3 (1.3 g, 98%), mp 249–251°C, [ꢃ] –292.0° (DMSO), HR-MS (EI, m/z): calcd for C H N OS, 249.0930 [M] ; found,
D
12 15 3
249.0923.
2
3
3
4
PMR spectrum (DMSO-d , ꢄ, ppm, J/Hz): 1.86 (1H, dtt, J = 13.3, J
= 3.4, J
= 3.4, J
= 1.7,
8syn-11endo
6
8syn-7
8syn-9
4
2
3
3
4
J
= 1.7, H -8); 1.93 (1H, dtd, J = 13.3, J
= 3.3, J
= 3.3, J
= 1.0, H -8); 2.49 (1H, m,
8syn-13endo
syn
8anti-7
8anti-9
8anti-10endo
3
anti
2
4
H-9); 3.09 (m, H-11); 3.15 (1H, m, H-7); 3.16 (m, H-13); 3.66 (1H, ddd, J = 15.3, J
= 6.7, J
= 1.0,
10exo-9
3
10exo-11exo
2
3
4
4
H
-10); 3.97 (1H, dt, J =15.3, J
= 1.0, J
= 1.0, H
-10); 6.14 (1H, dd, J = 7.0, J = 1.2, H-5);
exo
10endo-9
10endo-8anti
3
endo 5-4 5-3
3
4
3
6.21 (1H, dd, J = 9.0, J = 1.2, H-3); 7.32 (1H, dd, J = 9.0, J = 7.0, H-4).
3-4
3-5
4-3
4-5
631

13
C NMR spectrum (DMSO-d , ꢄ, ppm): 24.80 (C-8); 27.24 (C-9); 34.08 (C-7); 48.05 (C-10); 52.49 (C-11); 53.50
6
(C-13); 104.81 (C-5); 115.86 (C-3); 138.67 (C-4); 149.28 (C-6); 162.06 (C-2); 181.90 (C-14).
N-Allylcytisine-12-carbamide (4). Compound 4 was prepared according to the literature [19] in 98% yield,
20
+
mp 137–139°C, [ꢃ] –235.0° (CHCl ). HR-MS (EI, m/z): calcd for C H N O , 273.1472 [M] ; found, 273.1480.
D
3
15 19
3
3 2
2
3
4
PMR spectrum (CDCl , ꢄ, ppm, J/Hz): 1.94 (1H, dtd, J = 12.8, J
-8); 2.01 (1H, dtt, J = 12.8, J
H-9); 3.05 (1H, dd, J = 11.4,
= 3.0, J
= 1.6, J
= 3.0, J
= 1.0,
3
8anti-7
8anti-9
8anti-10endo
2
3
3
4
4
H
= 3.3, J
= 3.3, J
= 1.6, H -8); 2.52 (1H, m,
anti
8syn-7
8syn-9
8syn-11endo
8syn-13endo syn
2
3
2
3
J
= 2.3, H -13); 3.08 (1H, m, H-7); 3.10 (1H, ddd, J = 12.8, J
= 2.4,
= 1.6,
13exo-7
exo
11exo-9
4
2
3
3
4
4
J
= 1.2, H -11); 3.64 (1H, dtt, J = 15.7,
J
= 5.6,
J
= 5.6, J
= 1.6, J
11exo-10exo
exo
16A-15
4
16A-17
16A-18trans 16A-18cis
= 1.6, H -16); 3.87 (1H, ddd,
2
3
3
4
H -16); 3.75 (1H, dtt, J = 15.7, J
= 5.6, J
= 5.6, J
= 1.6, J
A
16B-15
16B-17
16B-18trans
16B-18cis
3
B
2
4
3
4
2
4
J = 15.7,
J
= 6.8,
J
= 1.2, H -10); 4.13 (1H, ddt, J = 11.4, J
= 3.4, J
= 1.6,
10exo-9
10exo-11exo
exo
13endo-7
4
13endo-11endo
2
3
4
J
= 1.6, H
-13); 4.14 (1H, ddt, J = 12.8, J
= 3.4, J
= 1.6, J
= 1.6, H
-11); 4.20
= 1.6,
13endo-8syn
endo
11endo-9
11endo-13endo
-10); 4.97 (1H, dq, J
11endo-8syn
endo
2
3
4
3
2
(1H, dt, J = 15.7,
J
= 0.9,
= 1.6,
-18); 5.31 (1H, t,
J
= 0.9,
H
= 10.3, J
10endo-9
10endo-8anti
-18); 5.00 (1H, dq,
endo
18cis-17
18cis-18trans
4
4
3
4
4
3
2
4
J
J
J
J
= 1.6,
J
H
J
= 17.1, J
= 1.6, J
= 1.6,
= 17.1,
18cis-16A
18trans-16B
17-18cis
18cis-16B
cis
18trans-17
18trans-18cis
= 5.6, H-N15); 5.72 (1H, ddt, J
= 5.6, H-17); 6.08 (1H, dd, J =7.0, J = 1.3, H-5); 6.40 (1H, dd, J = 9.1,
18trans-16A
3
3
3
= 1.6, H
J
= 5.6,
J
trans
15-16A
15-16B
17-18trans
3
3
3
3
4
= 10.3,
J
= 5.6,
J
17-16A
17-16B
5-4
5-3
3-4
3
3
= 1.3, H-3); 7.28 (1H, dd, J = 7.0, J = 9.1, H-4).
3-5
4-5
4-3
13
C NMR spectrum (CDCl , ꢄ, ppm): 25.85 (C-8); 27.38 (C-9); 34.59 (C-7); 43.15 (C-16); 49.10 (C-10); 50.38
3
(C-11); 50.99 (C-13); 105.60 (C-5); 114.97 (C-18); 116.82 (C-3); 135.69 (C-17); 139.00 (C-4); 149.65 (C-6); 157.96 (C-14);
163.43 (C-2).
N-Phenylcytisine-12-carbamide (5). Compound 5 was prepared according to the literature [19] in 98% yield,
20
+
mp 119–121°C, [ꢃ] –242° (CHCl ), HR-MS (EI, m/z): calcd for C H N O , 309.1472 [M] ; found, 309.1470.
D
3
18 19
3
2
2
3
3
4
PMR spectrum (CDCl , ꢄ, ppm, J/Hz): 1.87 (1H, dddd, J = 12.8, J
-8); 1.94 (1H, dtt, J = 12.8, J
H-9); 3.10 (1H, m, H-7); 3.05 (1H, dd, J = 12.3,
= 3.6, J
= 2.8, J
= 1.1,
3
8anti-7
= 1.7, J
8anti-9
8anti-10endo
2
3
3
4
4
H
= 3.4, J
= 3.4, J
= 1.7, H -8); 2.40 (1H, m,
anti
8syn-7
8syn-9
8syn-11endo
8syn-13endo syn
2
3
2
3
J
= 2.0, H -13); 3.09 (1H, ddd, J = 11.0, J
= 2.4,
13exo-7
exo
11exo-9
2
4
3
4
2
3
4
J
J
J
= 1.2, H -11); 3.83 (1H, ddd, J = 15.6, J
= 6.7, J
= 1.2, H -10); 4.17 (1H, ddt, J = 12.3,
-13); 4.23 (1H, ddt, J = 11.0,
11exo-10exo
exo
10exo-9
10exo-11exo exo
4
4
2
3
= 3.5,
J
= 1.7,
= 1.7, H
J
= 1.7,
H
J
= 3.4,
-10); 6.03
= 1.5,
13endo-7
13endo-11endo
13endo-8syn
-11); 4.23 (1H, dt, J = 15.6, J
endo
11endo-9
4
2
3
4
= 1.7, J
= 1.1, J
= 1.1, H
= 7.2, J
11endo-8syn
3
11endo-13endo
endo
10endo-9
10endo-8anti
3
endo
4
3
4
4
(1H, dd, J = 6.9, J = 1.1, H-5); 6.36 (1H, dd, J = 9.1, J = 1.1, H-3); 6.94 (1H, tt, J
5-4
5-3
3-4
3-5
19-18(20)
3
19-17(21)
3
3
3
H-19); 7.16 (2H, dd, J
= 7.4, J
= 7.2, H-18(20)); 7.23 (1H, dd, J = 9.1, J = 6.9, H-4); 7.24 (2H, dd,
18(20)-17(21)
18(20)-19 4-3 4-5
3
4
J
= 8.4, J
= 1.5, H-17(21)); 7.52 (1H, br.s, H-15).
17(21)-18(20)
13
17(21)-19
C NMR spectrum (CDCl , ꢄ, ppm): 25.79 (C-8); 27.43 (C-9); 34.59 (C-7); 49.09 (C-10); 50.89 (C-11); 51.35
3
(C-13); 105.66 (C-5); 117.12 (C-3); 120.49 (C-17(21)); 123.02 (C-19); 128.65 (C-18(20)); 139.12 (C-4); 149.37 (C-6); 156.18
(C-14); 163.50 (C-2).
N,N-Hexane-1,6-diyl-bis(cytisinecarbamide) (6). A solution of 1 (0.5 g, 2.6 mmol) in benzene was treated with
hexamethylene-1,6-diisocyanate (0.78 g, 1.4 mmol), refluxed until 1 disappeared completely (TLC monitoring), and concentrated
at reduced pressure. The solid was chromatographed over SiO with elution by benzene:MeOH (9:1) to afford 6 (1.1 g, 68%),
2
20
+
mp 120–123°C, [ꢃ] –168.0° (MeOH), HR-MS (EI, m/z): calcd for C H N O , 548.3106 [M] ; found, 548.3080.
D
30 70 6 4
PMR spectrum (CDCl , ꢄ, ppm, J/Hz): 0.99 (1H, m, H -18); 1.06 (1H, m, H -18); 1.19 (2H, m, H-17);1.95 (1H, dtd,
3
A
B
2
4
3
3
4
2
3
3
J = 12.7,
J
H -16); 3.01 (1H, dd, J = 13.0, J
J
= 3.0,
J
= 3.0, J
= 1.0, H -8); 2.00 (1H, dtt, J = 12.7, J
= 3.3, J
= 3.3,
= 5.0,
= 1.2,
8anti-7
8anti-9
8anti-10endo
anti
8syn-7
8syn-9
4
2
3
3
= 1.6,
J
= 1.6, H -8); 2.51 (1H, m, H-9); 2.92 (1H, dq, J = 12.0, J
= 12.0, J
8syn-11endo
8syn-13endo
2
syn
16A-17
16A-15
3
2
3
4
= 2.2, H -13); 3.08 (1H, ddd, J = 11.0, J
= 2.4, J
A
13exo-7
exo
11exo-9
11exo-10exo
2
2
3
3
H
-11); 3.09 (1H, m, H-7); 3.09 (1H, dq, J = 12.0, J
= 6.9, J
-13); 4.28 (1H, ddt, J = 11.0, J
= 12.0, J
= 5.0, H -16); 3.88 (1H, ddd, J = 15.5,
exo
16B-17
16B-15 B
3
4
2
3
4
4
J
= 1.2, H -10); 4.26 (1H, ddt, J = 13.0, J
= 3.4, J
= 1.6, J
= 1.6,
10exo-9
10exo-11exo
2
exo
13endo-7
4
13endo-11endo
13endo-8syn
2
3
4
H
= 3.4, J
= 1.6, J
= 1.6, H
-11); 4.30 (1H, dt, J = 15.5,
endo
11endo-9
11endo-13endo
3
11endo-8syn
endo
3
4
4
3
3
J
J
= 0.9,
J
= 0.9, H
-10); 5.93 (1H, t, J
= 5.0, J
= 5.0, H-15); 6.10 (1H, dd, J =7.1,
10endo-9
10endo-8anti
endo
15-16A
15-16B
5-4
3
4
3
3
= 1.0, H-5); 6.36 (1H, dd, J = 9.0, J = 1.0, H-3); 7.28 (1H, dd, J = 7.1, J = 9.0, H-4).
5-3
3-4
3-5
4-5
4-3
13
C NMR spectrum (CDCl , ꢄ, ppm): 25.92 (C-18); 25.98 (C-8); 27.52 (C-9); 29.74 (C-16); 34.70 (C-7); 40.29
3
(C-17); 49.17 (C-10); 50.42 (C-11); 50.76 (C-13); 105.93 (C-3); 116.63 (C-5); 139.28 (C-4); 149.90 (C-6); 158.21 (C-14);
163.50 (C-2).
12-Methyl-3-nitrocytisine (7a) and 12-Methyl-5-nitrocytisine (7b). Regioisomers 7a and 7b were prepared
according to the literature [16] in yields of 70 and 10%, respectively.
632

20
+
7a: mp 105–107°C, [ꢃ] –245° (MeOH), HR-MS (EI, m/z): calcd for C H N O , 249.1108 [M] ; found, 249.1121.
D
12 15 3 3
2
3
3
4
PMR spectrum (CDCl , ꢄ, ppm, J/Hz): 1.81 (1H, dtd, J = 13.0, J
= 3.1, J
= 1.6, J
= 3.1, J
= 1.1,
3
8anti-7
8anti-9
8anti-10endo
2
3
3
4
4
H
-8); 1.91 (1H, dtt, J = 13.0, J
= 3.3, J
= 3.3, J
= 1.6, H -8); 2.12 (3H, s,
anti
8syn-7
J
8syn-9
8syn-11endo
8syn-13endo syn
2
3
4
2
3
3H-14); 2.27 (1H, ddd, J = 11.4,
= 2.6,
J
= 1.3, H -11); 2.35 (1H, dd, J = 11.3,
J
= 2.3,
13exo-7
11exo-9
11exo-10exo
exo
2
3
4
H
-13); 2.51 (1H, m, H-9); 2.88 (1H, ddt, J = 11.3, J
= 3.5, J
= 1.6, 4J
= 1.6, H
-13); 2.89
exo
13endo-7
4
13endo-11endo
13endo-8syn
endo
2
3
4
(1H, ddt, J = 11.4, J
= 3.3, J
= 1.6, J
= 1.6, H
-11); 3.12 (1H, m, H-7); 3.97 (1H, ddd,
11endo-9
= 6.5, J
11endo-13endo
11endo-8syn
endo
2
3
4
3
4
J = 15.8, J
= 1.3, H -10); 4.13 (1H, dt, 2J = 15.8, J
= 1.1, J
= 1.1, H
-10);
10exo-9
3
10exo-11exo
exo
10endo-9
10endo-8anti
endo
3
6.16 (1H, d, J = 8.1, H-5); 8.32 (1H, d, J = 8.1, H-4).
5-4
4-3
13
C NMR spectrum (CDCl , ꢄ, ppm): 24.57 (C-8); 27.49 (C-9); 36.27 (C-7); 45.89 (C-14); 51.24 (C-10); 61.48
3
(C-13); 61.80 (C-11); 102.87 (C-5); 134.46 (C-3); 137.85 (C-4); 155.26 (C-6); 161.01 (C-2).
20
+
7b: mp 138–141°C, [ꢃ] –350.0° (MeOH), HR-MS (EI, m/z): calcd for C H N O , 249.1108 [M] ; found, 249.1122.
D
12 15 3 3
3
2
PMR spectrum (CDCl , ꢄ, ppm, J/Hz): 1.83 (2H, t, J
= 3.2, 2H-8); 2.17 (3H, s, 3H-14); 2.26 (1H, ddd, J = 11.1,
3
8-7(9)
3
4
2
3
J
= 3.3, J
= 1.2, H -11); 2.34 (1H, dd, J = 11.4, J
= 2.6, H -13); 2.48 (1H, m, H-9); 2.90 (1H,
11exo-9
2
11exo-10exo
exo
13exo-7 exo
3
4
4
2
3
ddt, J = 11.1, J
= 3.3, J
= 1.6, J
= 1.6, H
-11); 3.28 (1H, ddt, J = 11.4, J
= 3.3,
13endo-7
11endo-9
4
11endo-13endo
11endo-8syn
-13); 3.98 (1H, ddd, J = 15.7, J
endo
3
4
2
4
J
= 1.6, J
= 1.6, H
= 6.2, J
= 1.2, H -10); 4.02
13endo-11endo
13endo-8syn
2
endo
10exo-9
10exo-11exo
3
exo
3
4
(1H, m, H-7); 4.05 (1H, dt, J = 15.7, J
= 1.0, J
= 1.0, H
-10); 6.45 (1H, d, J = 10.0, H-3); 8.13 (1H,
10endo-9
10endo-8anti
endo 3-4
3
d, J =10.0, H-4).
4-3
13
C NMR spectrum (CDCl , ꢄ, ppm): 24.97 (C-8); 27.15 (C-9); 31.75 (C-7); 46.05 (C-14); 51.79 (C-10); 60.12
3
(C-13); 62.00 (C-11); 115.86 (C-3); 128.36 (C-5); 134.97 (C-4); 155.33 (C-6); 162.33 (C-2).
3-Amino-12-methylcytisine (8). Compound 8 was prepared from 7a according to the literature [16] in 98% yield,
20
+
mp 169–172°C, [ꢃ] –113.0° (MeOH), HR-MS (EI, m/z): calcd for C H N O, 219.1366 [M] ; found, 219.1365.
D
12 17
3
3
2
3
4
PMR spectrum (CDCl , ꢄ, ppm, J/Hz): 1.68 (1H, dtd, J = 12.5, J
-8); 1.80 (1H, dtt, J = 12.5,
3H-14); 2.17 (1H, ddd, J = 11.1,
-13); 2.37 (1H, m, H-9); 2.76 (1H, ddt, J = 10.5, J
(1H, m, H-7); 2.85 (1H, ddt, J = 11.1, J
= 3.2, J
= 1.7, J
= 3.2, J
= 1.3,
3
8anti-7
8anti-9
8anti-10endo
2
3
3
4
4
H
J
= 3.4,
J
= 3.4,
J
= 1.7, H -8); 2.09 (3H, s,
anti
8syn-7
J
8syn-9
4
8syn-11endo
8syn-13endo syn
= 1.2, H -11); 2.18 (1H, dd, J = 10.5, J
2
3
2
3
= 2.4,
J
= 2.2,
13exo-7
11exo-9
11exo-10exo
exo
2
3
4
4
H
= 3.4, J
= 1.7, J
= 1.7, H
-13); 2.84
exo
13endo-7
13endo-11endo
4
13endo-8syn
= 1.7, H
endo
2
3
4
= 3.4, J
= 1.7, J
-11); 3.91 (1H, ddd,
11endo-9
11endo-13endo
2
11endo-8syn
endo
2
3
4
3
4
J = 15.1, J
= 6.8, J
= 1.3, H -10); 4.09 (1H, dt, J = 15.1, J
= 1.0, J
= 1.0, H
-10);
endo
10exo-9
3
10exo-11exo
exo
10endo-9
10endo-8anti
3
5.85 (1H, d, J = 7.2, H-5); 6.53 (1H, d, J = 7.2, H-4).
5-4
4-5
13
C NMR spectrum (CDCl , ꢄ, ppm): 26.01 (C-8); 28.00 (C-9); 34.79 (C-7); 46.27 (C-14); 50.18 (C-10); 62.31
3
(C-11); 63.19 (C-13); 104.29 (C-5); 113.03 (C-4); 134.67 (C-3); 138.50 (C-6); 158.30 (C-2).
N-(12-Methylcytisin-3-yl)-Nꢀ-allylurea (9). Compound 9 was prepared according to the literature [19] in 98%
20
+
yield, mp 176–179°C, [ꢃ] –63.3° (CHCl ), HR-MS (EI, m/z): calcd for C H N O , 302.1737 [M] ; found, 302.1711.
D
3
16 22 4 2
2
3
3
4
PMR spectrum (CDCl , ꢄ, ppm, J/Hz): 1.73 (1H, dtd, J = 13.3, J
= 3.4, J
= 3.4, J
= 1.7, H -8); 2.09 (3H, s,
= 1.3,
3
8anti-7
8anti-9
8anti-10endo
2
3
3
4
4
H
-8); 1.83 (1H, ddt, J = 13.3, J
= 3.4, J
= 2.5, J
= 3.4, J
= 1.7, J
anti
8syn-7
8syn-9
8syn-11endo
8syn-13endo
2
syn
2
3
4
3
H-14); 2.21 (1H, ddd, J = 11.3, J
= 1.0, H -11); 2.22 (1H, dd, J = 11.2, J
= 2.4, H -13);
-13); 2.83 (1H, ddt,
11exo-9
11exo-10exo
exo
13exo-7 exo
2
3
4
4
2.36 (1H, m, H-9); 2.80 (1H, ddt, J = 11.2, J
= 3.1, J
= 1.7, J
= 1.7, H
13endo-7
13endo-11endo
= 1.7, H
13endo-8syn
endo
2
3
3
4
4
2
J = 11.3, J
= 3.3, J
= 1.7, J
-11); 2.94 (1H, m, H-7); 3.85 (1H, ddd, J = 15.3,
11endo-9
4
11endo-13endo
11endo-8syn
endo
2
3
4
J
= 6.6, J
= 1.0, H -10); 3.95 (2H, m, H-18); 3.98 (1H, dt, J = 15.3, J
= 1.0, J
= 17.0, J
= 1.0,
= 1.9,
10exo-9
10exo-11exo
-10); 5.08 (1H, dq,
exo
10endo-9
10endo-8anti
4
3
4
3
= 1.7, H -20); 5.24 (1H, dq, J
cis
H
J
= 10.2,
J
endo
trans
20cis-19
20cis-18
20trans-19
3
20trans-18
3
3
3
H
-20); 5.93 (1H, ddt, J
= 17.1, J
= 10.2, J
= 5.9, H-19); 6.11 (1H, d, J = 7.8, H-5); 7.52 (1H, t,
19-20trans
3
19-20cis
19-18 5-4
3
J
= 5.5, H-17); 8.30 (1H, d, J = 7.8, H-4); 8.90 (1H, s, H-15).
17-18
4-5
13
C NMR spectrum (CDCl , ꢄ, ppm): 25.50 (C-8); 27.70 (C-9); 34.61 (C-7); 42.20 (C-18); 46.08 (C-14); 50.76
3
(C-10); 61.96 (C-11); 62.62 (C-13); 106.18 (C-5); 114.81 (C-20); 120.54 (C-4); 128.28 (C-3); 136.37 (C-19); 140.72 (C-6);
156.26 (C-16); 157.70 (C-2).
N-(12-Methylcytisin-3-yl)-Nꢀ-phenylurea (10). Compound 10 was prepared according to the literature [19] in 98%
20
+
yield, mp 109–112°C, [ꢃ] –34.5° (CHCl ), HR-MS (EI, m/z): calcd for C H N O , 338.1737 [M] ; found, 338.1716.
D
3
19 22
3
3
2
2
3
4
PMR spectrum (DMSO-d , ꢄ, ppm, J/Hz): 1.66 (1H, dtd, J = 13.3, J
= 3.4, J
= 3.4, J
= 1.7, H -8); 2.04 (3H, s,
= 1.3,
6
8anti-7
8anti-9
8anti-10endo
2
3
3
4
4
H
-8); 1.79 (1H, ddt, J = 13.3,
J
= 3.4, J
= 2.5, J
= 3.4, J
= 1.7, J
anti
8syn-7
8syn-9
8syn-11endo
8syn-13endo
2
syn
2
3
4
3
H-14); 2.12 (1H, ddd, J = 11.3, J
= 1.0, H -11); 2.16 (1H, dd, J = 11.2, J
= 2.4, H -13);
-13); 2.86 (1H, ddt,
11exo-9
11exo-10exo
exo
13exo-7 exo
2
3
4
4
2.38 (1H, m, H-9); 2.72 (1H, ddt, J = 11.2, J
= 3.3, J
= 1.7, J
= 1.7, H
13endo-7
13endo-11endo
= 1.7, H
13endo-8syn
endo
2
3
4
4
2
J = 11.3, J
= 3.3, J
= 1.7, J
-11); 2.98 (1H, m, H-7); 3.82 (1H, ddd, J = 15.3,
11endo-9
11endo-13endo
11endo-8syn
endo
633

3
4
2
3
4
J
= 6.7, J
= 1.0, H -10); 3.93 (1H, dt, J = 15.3, J
= 1.0, J
= 1.0, H
-10); 6.12 (1H,
10exo-9
10exo-11exo
exo
10endo-9
10endo-8anti
endo
3
3
3
4
d,
J
= 7.8, H-5); 6.98 (1H, tt,
J
= 9.0,
J
= 1.1, H -Ph); 7.27 (1H, dd,
J
= 9.0,
5-4
para-meta
3
para-ortho
4
para
= 1.1, H
meta-para
3
3
J
= 7.3, H
-Ph); 7.45 (1H, dd, J
= 7.3, J
-Ph); 8.02 (1H, d, J = 7.8, H-4); 8.51
20meta-ortho
meta
ortho-meta
ortho-para
ortho
4-5
(1H, s, H-15); 9.52 (1H, s, H-17).
13
C NMR spectrum (DMSO-d , ꢄ, ppm): 24.88 (C-8); 27.00 (C-9); 33.80 (C-7); 45.76 (C-14); 50.23 (C-10); 61.60
6
(C-11); 62.46 (C-13); 103.51 (C-5); 117.69 (C-19); 118.96 (C-4); 121.63 (C-21); 126.62 (C-3); 128.71 (C-20); 139.67 (C-18);
142.15 (C-6); 152.42 (C-16); 156.81(C-2).
ACKNOWLEDGMENT
The work was supported by RFBR Grant No. 12-03-00724-a and RAS Otd. Khim. Nauk Mater. (OKhNM) Program
No. 9 (Medicinal Chemistry: Molecular Design of Physiologically Active Compounds and Drugs).
REFERENCES
1.
2.
http://www.alz.co.uk/research/files/WorldAlzheimerReport.pdf
R. M. Sousa, C. P. Ferri, D. Acosta, E. Albanese, M. Guerra, Y. Huang, K. S. Jacob, A. T. Jotheeswaran,
J. J. Llibre Rodriguez, G. Rodriguez Pichardo, M. Calvo Rodriguez, A. Salas, A. L. Sosa, J. Williams, T. Zuniga,
and M. Prince, Lancet, 374, 1821 (2009).
3.
4.
P. K. Fischhof, B. Saletu, E. Ruther, G. Litschauer, R. Moslinger-Gehmayr, and W. M. Herrmann,
Neuropsychobiology, 26, 65 (1992).
L. G. Neyens, W. C. Alpherts, and A. P. Aldenkamp, Prog. Neuro-Psychopharmacol. Biol. Psychiatry, 19,
411 (1995).
5.
6.
7.
B. Winblad, CNS Drug Rev., 11, 169 (2005).
M. Romanelli and P. Gratteri, Med. Res. Rev., 23, 393 (2003).
M. Romanelli, P. Gratteri, L. Guandalini, E. Martini, C. Bonnacini, and F. Gualtieri, Chem. Med. Chem., 2,
746 (2007).
8.
9.
P. M. Joyner and R. H. Cichewicz, Nat. Prod. Rep., 28, 26 (2011).
C. Canu Boido and F. Sparatore, Farmaco, 54, 438 (1999).
10.
11.
12.
O. Nicolotti, C. Canu Boido, F. Sparatore, and A. Carotti, Farmaco, 57, 469 (2002).
C. Canu Boido, B. Tasso, V. Boido, and F. Sparatore, Farmaco, 58, 265 (2003).
G. Bombieri, F. Meneghetti, R. Artali, B. Tasso, C. Canu Boido, and F. Sparatore, Chem. Biodiversity, 5,
1867 (2008).
13.
B. Tasso, C. Canu Boido, E. Terranova, C. Gotti, L. Riganti, F. Clementi, R. Artali, G. Bombieri, F. Meneghetti,
and F. Sparatore, J. Med. Chem., 52, 4345 (2009).
14.
15.
16.
17.
P. Imming, P. Klaperski, M. T. Stubbs, G. Seitz, and D. Gundisch, Eur. J. Med. Chem., 36, 375 (2001).
N. Houllier, J. Copisetti, P. Lestage, M.-C. Lasne, and J. Rouden, Bioorg. Med. Chem. Lett., 20, 6667 (2010).
E. Marrire, J. Rouden, V. Tadino, and M.-C. Lasne, Org. Lett., 2(8), 1121 (2000).
J. Abin-Carriquiri, G. Costa, J. Urbanavicius, B. Cassels, M. Rebolledo-Fuentes, S. Wonnacott, and F. Dajas,
Eur. J. Pharmacol., 589, 80 (2008).
18.
19.
20.
21.
22.
V. N. Tikhonov, I. V. Komissarov, and V. V. Volobuev, Neirofiziologiya, 35, 26 (2003).
F. Moll and G. Luputiu, Arch. Pharm., 305, 771 (1972).
Handbook of Experimental (Preclinical) Study of New Drugs [in Russian], Moscow, 2005.
K. Nagayama, A. Kumar, K. Wuthrich, and R. R. Ernst, J. Magn. Reson., 40, 321 (1980).
Ya. Buresh, O. Bureshova, and D. Houston, in: Methods and Principal Experiments for Studying the Brain and
Behavior [in Russian], Vysshaya Shkola, Moscow, 1991.
23.
24.
T. A. Gudasheva, R. U. Ostrovskaya, S. S. Trofimov, M. Yu. Kosoi, F. V. Ienkina, Yu. V. Burov, and
A. P. Skoldinov, Khim.-farm. Zh., 11, 1322 (1985).
M. L. Belenꢀkii, Elements of Quantitative Assessment of the Pharmacological Effect [in Russian], Medgiz,
Leningrad, 1963.
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