N-alkylated 3,5-bis(arylidene)-4-piperidones. Synthetic approaches, x-ray structure and anticancer activity

Article abstract of DOI:10.1002/jhet.5570450315

(Chemical Equation Presented) In a search for cytotoxic fluorescent materials a series of N-alkylated and N,N-dialkylated 3,5-bis(arylidene) piperidones was synthesized. Alkylation of 3,5-bis(arylidene)-4-piperidone afforded quaternary salts only while condensation of N-alkyl-4-piperidones with substituted benzaldehydes was a convenient route to the corresponding N-alkylated compounds. Compounds and their pharmaceutically acceptable salts demonstrated high activity against resistant human lung carcinoma cell line A549 with IC₅₀ values in the range of 0.3-6.5 μM.

Full text of DOI:10.1002/jhet.5570450315

May-Jun 2008
729
N-Alkylated 3,5-bis(arylidene)-4-piperidones. Synthetic
Approaches, X-ray Structure and Anticancer Activity
Michael V.Makarova, Irina L.Odinets*a, Konstantin A. Lyssenkoa, Ekaterina Yu.
Rybalkinab, Ilya V. Kosilkinc, Mikhail Yu. Antipina,c, Tatiana V. Timofeevac
aA.N.Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova str., 28,
119991 Moscow, Russia
bInstitute of Carcinogenesis, Blokhin Russian Cancer Research Center, Russian Academy of Medical Science,
Kashirskoe sh. 24, 115478 Moscow, Russia
cNew Mexico Highlands University, Las Vegas, NM 87701, USA
Received May 8, 2007
O
O
O
N
R1C6H4C(O)H
AlkHal
X = H
R1
N
X
R1
R1
R1
Hal
Alk
N
X
Alk
X = H, Alk
R1 = F, NO2, NMe2; Alk = Et, Pr, Bu; Hal = Br, I
In a search for cytotoxic fluorescent materials a series of N-alkylated and N,N-dialkylated 3,5-
bis(arylidene)piperidones was synthesized. Alkylation of 3,5-bis(arylidene)-4-piperidone afforded
quaternary salts only while condensation of N-alkyl-4-piperidones with substituted benzaldehydes was a
convenient route to the corresponding N-alkylated compounds. Compounds and their pharmaceutically
acceptable salts demonstrated high activity against resistant human lung carcinoma cell line A549 with
IC50 values in the range of 0.3-6.5 µM.
J. Heterocyclic Chem., 45, 729 (2008).
INTRODUCTION
NH-3,5-bis(arylidene)-4-piperidones
having also anti-inflammatory [6a], antibacterial [6b] and
antioxidative [6c] properties. Thus, curcumin and other
enones were supposed to have multiple targets and
interacting macromolecules within the cell [3,5]. It should
be mentioned also that a few N-alkylated 3,5-bis-
(arylidene)-4-piperidones as curcumin analogues were
reported as good free radical scavengers possessing also
high cytostatic properties. However, the above mentioned
properties were attributed to the presence of hydroxyl
groups in the para-position of aromatic rings and alkoxy
groups at the adjacent aromatic carbon atoms [10].
According to the Dimmock’s hypothesis [1] for 3,5-
bis(arylidene)-4-piperidones the molecular modification
at the nitrogen atom such as N-acylation 2a, affects the
capacity of transportation of these biologically active
molecules acting as a thiol acylators via the cellular
membrane and therefore results in significantly higher
level of anticancer activity. Similar approach comprises
phosphorylation of such NH-piperidones (compounds 2b,
Recently
1
bearing F, Cl, NO2 or NMe2 substituents in the para-
position of the aromatic ring (Scheme 1) were found to
possess cytotoxic and antitumor activity [1-3]. In addition,
their hydrochloride salts were well tolerated in mice (up
to 240 mg/kg) [3]. The idea of their synthesis and
evaluation of antineoplastic properties initially was based
on the reasons that such compounds may be considered as
Mannich base of a dienone and α,β-unsaturated ketones
display anticancer properties via the supposed mechanism
of action comprising interaction with cellular thiols with
little or no affinity for hydroxyl and amino groups in
nucleic acids [4]. Among those curcumin (1,7-bis(4-
hydroxy-3-methoxyphenyl)-1,6-heptadien-3,5-dione),
a
natural component of the rhizome of curcuma longa
possessing a conjugated structure, proved to be the
powerful chemopreventive and anticancer agent [5]
Scheme 1
O
O
R1
N
H
1
R1
R1
N
R1
Y
2a,b
R1 = Cl, F, NO2, OMe
R1 = NMe2
2a: Y = C(O)CH3, C(O)OEt, C(O)CH=CH2
2b: Y = P(O)(OCH2CF3)2, P(O)(OPh)2, P(O)Me(OPh)

730
M. Makarov, I. Odinets, K.Lyssekko, E.Rubalkina, I.Kosilkin, M.Antipin, T. Timofeeva
Vol 45
Scheme 1) [7]. Both acylated and phosphorylated
compounds may be considered as pro-drugs giving the
parent NH-compound via hydrolysis in vivo under the
action of the suitable enzymes.
Fluorescent properties of the compounds belonging to
the class of 3,5-bis(arylidene)-4-piperidones were
reported for the first time for the corresponding N-methyl
derivatives [8,9]. Therefore, despite the rupture of N-
C(alkyl) bond in such compounds in vivo resulting NH-
piperidones 1 is less obvious comparing with derivatives
2a,b, it was of interest to estimate the anticancer activity
of such N-alkyl substituted substances. Thus, in this paper
we report our results on the synthesis, structural
characterization, and assessment of anticancer activity of
a series of N-alkylated 3,.5-bis(arylidene)-4-piperidones
and their derivatives with quaternized nitrogen atom.
Therefore, 1,5-diaryl-3-oxo-1,4-pentadienyl pharmaco-
phore group observed both in alicyclic unsaturated enones
and cyclic piperidone derivatives was speculated as
interacting with cellular constituents while the nature of
the group on the heterocyclic nitrogen atom in the latter
ones could influence the cytotoxic properties of a
compound. In other words, it can increase the cytotoxic
properties by facilitating of the cytotoxin approach to a
specific binding site or reduce them preventing their
interaction.
RESULTS AND DISCUSSION
Synthesis of drug candidates. Principally, the target
N-alkyl-3,5-bis(arylidene)-4-piperidones may be prepared
either by direct alkylation of the preformed skeleton of
3,5-bis(arylidene)-4-piperidones or by the condensation of
Recent
observations
demonstrated
fluorescent
properties of some representatives of 3,5-bis(arylidene)-4-
piperidones [7-9]. Natural fluorescence in the case of
cytotoxic materials might be very helpful in tracking of
their cellular pathway. Structure-activity relationships
allow suggesting that cytotoxic activity increases with the
increase of electron withdrawing properties of the phenyl
ring substituents, which at the same time decrease the
fluorescent activity. Combination of anti-tumor activity
and two-photon fluorescent properties makes this type of
compounds exceedingly prospective as drug-candidates
for photodynamic chemotherapy of superficial malignant
tumors and will aid in tracing their pathways during
chemotherapeutic treatment. Therefore, in order to
N-alkyl-4-piperidones
with
substituted
aromatic
aldehydes in the presence of acid or base. However,
taking into account commercial availability of the
piperidin-4-one hydrochloride salt monohydrate, it seams
reasonable to use condensation reaction of piperidin-4-
one with appropriate aldehyde followed by introduction of
an alkyl group into the corresponding 3,5-bis(arylidene)-
4-piperidone by interaction with halogenoalkane.
Assuming that nucleophilicity of the nitrogen atom of
an arylidenepiperidone could be diminished by the
Scheme 2
O
O
5
6
4
7
8
AlkI
3'
2'
3
2
11
9
10
CH3CN, K2CO3
R1
N
R1
R1
N
R1
Alk
Alk
H
I
3a,b
R1 = NMe2 (3a), F (3b)
4a-d
R1 = NMe2; Alk = Et (4a), n-Pr (4b), n-Bu (4c)
R1 = F; Alk = Et (4d)
Table 1
Reaction of bis(arylidene)piperedones 3a,b with iodoalkanes via Scheme 2.
Run
Starting
AlkJ
3a (3b)/AlkJ
Temp, ºC
Time, h
Yield of 4, %a
substrate
1
2
3
4
5
6
3a
3a
3a
3a
3a
3b
EtJ
EtJ
n-PrJ
n-PrJ
n-BuJ
EtJ
1.3/1
5/1
5/1
5/1
5/1
5/1
20-25
20-25
20-25
80
80
80
30
24
12
70
∼100(64)
100(78)
0
75(37)
70(44)b
50c(28)
80
20-25
a According to the 1H NMR data, in brackets isolated yields after purification. b isolated as complex with KJ. c according
to the 19F NMR spectrum
develop efficient antitumor agents among the
bis(arylidene)-4-piperidone derivatives it seems necessary
to find the appropriate balance between these two
essential features.
influence of electron-withdrawing carbonyl group, the
reaction would require good alkylating agent, for
example, iodoalkane. In order to test these assumption, we
carried out the reaction of 3,5-bis[4-(dimethylamino)-

May-Jun 2008
N-alkylated 3,5-bis(arylidene)-4-piperidones
731
benzylidene]piperidin-4-one 3a with 1.3 equivalents of
iodoethane using biphasic system K2CO3/CH3CN (Table
1, run 1). Surprisingly, the reaction mixture comprised
mainly the starting compound 3a and the quaternary salt
4a according to the NMR data. Pure quaternary salt may
be easily obtained by crystallization of reaction product
from CH2Cl2 – Et2O. When the alkylation of 3,5-bis[4-
(dimethylamino)benzylidene]piperidin-4-one 3a was
carried out with five equivalents of iodoethane, the salt 4a
was the sole reaction product (Scheme 2, Table 1, run 2).
When 3a was treated with less reactive bromoethane, a
mixture of the starting substrate 3a and the quaternary salt
4a-Br was obtained as well. However the 4a-Br salt
bearing bromine anion was isolated in a low yield. It is
noteworthy, that interaction of piperidin-4-one with
bromoethane taken in equimolar amounts, resulted in N-
ethyl-piperidin-4-one as the only reaction product (see
Experimental part).
Figure 1. The general view of 4d in representation of atoms by thermal
ellipsoid plots (p=50%). The selected bond lengths (Å): O(1)-C(1)
1.224(3), N(1)-C(3) 1.505(3), N(1)-C(4)
1.508(3), N(1)-C(20)
1.514(3),N(1)-C(22) 1.524(3), C(1)-C(2) 1.485(4), C(1)-C(5) 1.486(4),
C(2)-C(6) 1.340(4), C(5)-C(13) 1.349(4); bond angles (º): C(3)-N(1)-
C(4) 108.7(2), C(2)-C(1)-C(5) 117.8(2), C(1)-C(2)-C(6) 116.7(2), C(1)-
C(5)-C(13), 116.9(2).
Although the quaternization of 3a with iodoethane
proceeded smoothly at room temperature, it turned out
that both n-iodopropane and n-iodobutane did not alkylate
bisbenzylidenepiperidin-4-one 3a under presented
conditions (Table 1, run 3). However, performing the
same reactions in refluxing acetonitrile affords the corre-
sponding piperidonium salts 4b,c (Table 1, runs 4, 5).
Alkylation of para-fluorine substituted derivative 3b
proceeds in similar manner with compound 3a giving the
corresponding salt. Nevertheless, the increase of electron
withdrawing properties of the substituent R1 changes the
reaction course. Namely, interaction of 3,5-bis(4-
nitrobenzylidene)piperidin-4-one with iodoethane gave N-
obtained earlier for similar compounds [6,7,8,11-15].
Taking into consideration the general similarity of the
spectral data we also assigned the structures of
compounds 4a-c to E,E-isomers. Principal geometrical
parameters of 4d are in range of standard values with
typical lengthening of the N-C bonds from the protonated
nitrogen N(1) to values 1.50 Å. The heterocyclic
piperidone ring of 4d has the flattened chair conformation
(Figure 1) with the significant deviation of N(1) and slight
deviation of C(1) atoms by 0.701(4) and - 0.109(4) Å
respectively from the plane formed by C(2), C(3), C(4)
and C(5) atoms (rms deviation 0.012 Å) caused by sp2
character of carbon atom C(1). It should be noted that for
similar compounds deviation of C(1) atom from such
plane might be positive or negative [11-15] so central core
conformation of these molecules might be described as
flattened chair or boat; this conformation also can be
characterized as a sofa.
1
monoalkylated product (ca. 35-45% according H NMR)
which we failed to separate from other products of non-
identified structure.
Therefore, in contrast to piperidin-4-one, the alkylation
of its 3,5-arylidene derivatives bearing substituents
possessing either donor or moderate acceptor properties in
the para-position of phenyl rings proceeds according to
the quaternization scheme. An interesting feature of some
quaternary salts prepared in this study is their ability to
form strong complexes with potassium iodide (bromide).
For example, recrystallization of crude reaction mixtures
resulted in co-crystallizates of 4a-Br, 4c, and 4d with
potassium bromide or potassium iodide correspondingly
rather than the individual salts. In the case of 4d, the
crystallized product also contained iodoethane (this
fact was unambiguously confirmed by 1H-NMR
spectroscopy). Moreover, repeated crystallization did not
remove potassium iodide (bromide) from the above
products. Pure salts 4a-Br and 4d were obtained only
after washing their complexes with water.
To obtain the desired N-monoalkylated bis(arylidene)-
piperidones 6a-d, we have chosen the other possibility
that was mentioned above and performed a condensation
of pre-alkylated N-alkyl-piperidones with the corre-
sponding aromatic aldehydes followed by transformation
of the hydrochloride salts to the free bases (Scheme 3).
Condensation of aromatic aldehydes with N-alkyl-4-
piperidones may be performed in the presence of either
acid or base. The conditions which were reported in
literature include the application of aqueous ethanolic
potassium hydroxide or hydrogen chloride in absolute
ethanol [16].
The structure of representative quaternary salt 4d was
confirmed by X-ray data. Both olefinic bonds have E
configuration, which is in agreement with the results
In some cases, alkylpiperidone is able itself to catalyze
this reaction. Indeed, condensation of N-methyl-4-

732
M. Makarov, I. Odinets, K.Lyssekko, E.Rubalkina, I.Kosilkin, M.Antipin, T. Timofeeva
Vol 45
Scheme 3
O
R1
+
HC
O
2
N
X
HCl/AcOH
O
O
K2CO3
CH2Cl2, H2O
R1
N
R1
R1
N
R1
xHCl
Alk
6a-e
Alk
5a-e
Alk = Me, R1 = NMe2 (a), NEt2 (b), NO2 (c), F (d)
Alk = Et, R1 = NO2 (e)
piperidone with aldehydes proceeds smoothly when
carried out in boiling ethanol [17]. Sometimes organic
solvent is not present, and a mixture of aldehyde and
alkyl-4-piperidone is heated in the presence of
concentrated hydrochloric acid [18]. In the present work
we have used the procedure described by Dimmock et al.
[2a], i.e. bubbling of gaseous hydrogen chloride through
the solution of N-alkyl-4-piperidone and aldehyde in
glacial acetic acid. Under these conditions the interaction
proceeds smoothly to give the hydrochlorides of the
desired compounds in 69-90% yield depending on the
substituents in the reacting substrates. The free bases were
easily obtained on treatment with potassium carbonate in
water/CH2Cl2 two-phase system. Both salts 5 and free
bases 6 were isolated as solids of bright-yellow to dark-
orange color.
Cytotoxic activity. The cytotoxic activity of 12
compounds synthesized was tested on human cell line
A549 (lung carcinoma). This cell line is known to be
rather stable for drugs as possessing ABC-transporters,
namely BCRP, LRP, MDR1 (proteins responsible for
multiple drug resistance) [9]. The choice of such cell line
was connected with our suggestion that good results in
this particular case would provide even better activity
when applying non-resistant tumor cell lines.
active that a parent NH-piperidone 3a and the most active
one among the compounds tested. Alkylated piperidones
6c,e and the corresponding hydrochloride salts 5c,e
bearing NO2 substituents in the benzene rings possess
excellent cytotoxic activity for this cell line (IC50<1.5,
Table 2) which was at least twice higher than that for
Melphalan. The activity in this series of compounds
reduced with decreasing of acceptor properties and
appearance of donor properties of the substituents R1, i.e.
for compounds 5d, 6d (R1=F) and 5a,b, 6a,b (R1=NAlk2).
In all the cases salts 5 were slightly more active that the
corresponding free bases 6. Such higher activity is
apparently attributed to the better solubility of salts 5 in
aqueous media in comparison with 6. On the other hand,
for the salts 4, the above-mentioned compound 4a with
R1=NMe2 was more then 10-fold active than its analogue
4d with the p-fluorine atoms. Therefore, we may mention
the clear tendency: formation of piperidonium structures
Table 2
In vitro growth inhibition concentrations (IC50) of the
testedcompounds against A549 tumor cell line
Cmpd.
R1
Alk
Alk/H
Hal
IC50 (µM)
3a
3b
3c
4a
NMe2
F
NO2
NMe2
F
NMe2
NMe2
NEt2
NEt2
NO2
NO2
F
-
-
H
H
H
Et
Et
H
-
-
1.4±0.4
-
-
0.8±0.07
0.4±0.1
For comparison the activity of parent NH-piperidons
3a-c bearing the same substituents in the phenyl rings was
estimated in the same assay. Anticancer agent Melphalan
(Sarcolysin) was used as a positive control similar to
assays of cytotoxic properties of other 3,5-bis(arylidene)-
4-piperidone derivatives described in literature [1-7]. It
should be noted that the activity of some analogues of
compounds 6 against non-resistant murine tumor cell lines
was reported in ref. 6.
Et
J
0.30±0.05
4.0±0.2
5.00±0.17
5.00±0.26
4.00±0.13
6.5±0.2
4d
5a
Et
J
Cl
-
Me
Me
Me
Me
Me
Me
Me
Me
Et
6a
5b
6b
5c
H
-
Cl
H
-
H
-
Cl
Cl
Cl
0.72±0.01
1.50±0.05
1.50±0.07
3.0±0.2
6c
5d
6d
5e
F
In principle, introduction of alkyl groups to the
heterocyclic nitrogen atom resulted in decrease of
cytotoxic activity excluding compound 4a being more
NO2
NO2
H
-
1.3±0.1
1.50±0.05
4.0±0.1
6e
Melphalan
Et

May-Jun 2008
N-alkylated 3,5-bis(arylidene)-4-piperidones
733
(dimethylamino)benzylidene]piperidin-4-one 3a (0.36 g,
1
mmol), iodoethane (0.78 g, 5 mmol) and potassium carbonate
(0.41 g, 3 mmol) was stirred in CH3CN (10 mL) for about 80
hours at room temperature. Then CH2Cl2 was added to the
reaction mixture, and inorganic salts were filtered off. Volatiles
were removed in vacuum. The solid was dissolved in CH2Cl2,
and the solution was filtered. After evaporation of the solvent,
result in increase of the biological activity in a series of
bis(3,5-arylidene)piperidin-4-ones.
As mentioned above, the presence of conjugated bonds
system results in fluorescent properties of 3,5-bis-
(arylidene)piperid-4-one derivatives (two-photon
absorption) [7-9]. Fluorescent properties of the compounds
obtained allowed one to estimate their distribution in cancer
cells and such experiment was performed using compound
6b as a representative example. The result presented in
Fig. 2 indicated that the substance does not enter the cell
nuclei and is located in cell cytoplasm only (blank and
white spots on the Figure respectively).
the solid (0.54 g) was crystallized from
CH3CN/Et2O to give compound 4a (0.42 g, 78 %) as red-orange
solid. Mp. 235 °C (decomp.). 1H NMR (CDCl3) δ: 1.21 (t, 3JHH
a mixture of
=
7.1 Hz, 6H, N(CH2CH3)2), 3.05 (s, 12H, 2 N(CH3)2), 3.70 (q,
3JHH = 7.1 Hz, 4H, N(CH2CH3), 5.06 (m, 4H, NCH2), 6.73 (d,
3JHH = 8.9 Hz, 4H, C6H4), 7.36 (d, 3JHH = 8.9 Hz, 4H, C6H4), 8.10
(s, 2H, CH=). 13C NMR (CDCl3) δ: 7.91 (N+CH2CH3), 38.85
(NCH3), 53.63 (N+CH2CH3), 58.59 (N+CH2 (cyclic)), 111.79 (C8,
C10), 117.57 (C6), 120.21 (CH=C), 133.15 (C7,C11), 144.21
(CH=C), 151.60 (C9), 180.00 (C=O). IR (KBr) ν, cm-1: 2972,
2917, 2855, 1655 (C=O), 1614 (C=C), 1574, 1522, 1443, 1371,
1314, 1280, 1231, 1186, 1171, 1127, 984, 941, 818. Anal. Calcd.
for C27H36IN3O: C, 59.45%; H, 6.65%; N, 7.70%. Found: C,
59.28%; H, 6.74%; N, 7.61%.
When the reactants were used in 1:1.3 molar ratio the salt 4a
was isolated in 64% yield after recrystallization from
CH2Cl2/Et2O as red-orange solid.
(3E,5E)-3,5-Bis[4-(dimethylamino)benzylidene]-1,1-diethyl-
4-oxopiperidinium bromide (4a-Br). Using similar procedure
and starting from 3a (0.36 g, 1 mmol) and bromoethane (0.55 g,
5 mmol), complex of compound 4a-Br with potassium bromide
was isolated as red-orange solid (0.18 g, 35 %). Anal. Calcd. for
(C27H36BrN3O)5•KBr: C, 62.09%; H, 6.95%; N, 8.05%. Found:
Figure 2. Fluorescence image of the A 549 cells, taken 2 hours after
treatment with 6b compound (1 µM). The nuclei were stained by
Hoechst 33258 (black spots).
1
C, 62.14%; H, 7.02%; N, 7.75%. Mp. 230 – 233 °C. H NMR
3
(CDCl3) δ: 1.21 (t, JHH = 7.1 Hz, 6H, N(CH2CH3)2), 3.05 (s,
3
12H, 2 N(CH3)2), 3.70 (q, JHH = 7.1 Hz, 4H, N(CH2CH3), 5.06
In conclusion, for the synthesis of N-C1-C4-alkylated
3,5-bis(arylidene)-4-piperidones useful as anticancer
drug-candidates which activity depends on the lipophilic
nature of molecular structure as well as their solubility in
body liquids, a condensation of preformed N-alkyl-4-
piperidones with the substituted benzaldehydes presents
only one convenient route.
3
(m, 4H, NCH2 (cyclic), 6.73 (d, JHH = 8.9 Hz, 4H, C6H4), 7.36
3
(d, JHH = 8.9 Hz, 4H, C6H4), 8.10 (s, 2H, CH=). This complex
was treated with a mixture of water (15 mL) and CH2Cl2 (15
mL). Organic phase was separated, dried over Na2SO4 and
evaporated at reduced pressure to afford free compound 4a-Br as
red-orange solid (0.15 g, 30 %) with the same 1H NMR. Mp. 230
– 233 °C (decomp.). Anal. Calcd. for C27H36BrN3O: C, 65.05%;
H, 7.28%; N, 8.43%. Found: C, 64.73%; H, 7.19%; N, 8.05%.
(3E,5E)-3,5-Bis[4-(dimethylamino)benzylidene]-4-oxo-1,1-
dipropylpiperidinium iodide (4b). A mixture of 3,5-bis[4-
EXPERIMENTAL
(dimethylamino)benzylidene]piperidin-4-one 3a (0.36 g,
1
NMR spectra were recorded with a Bruker AMX-400
spectrometer (1H, 400.13, 19F, 376.3 and 13C, 100.61 MHz) using
residual proton signals of deuterated solvent as an internal
standard (1H, 13C) and CFCl3 (19F) as an external standard. The
13C NMR spectra were registered using the JMODECHO mode;
the signals for the C atom bearing odd and even numbers of
protons have opposite polarities. IR spectra were recorded in
mmol), iodopropane (0.85 g, 5 mmol) and calcined potassium
carbonate (0.61 g, 4.4 mmol) was refluxed with stirring in
CH3CN (10 mL) for about 24 h. Then CH2Cl2 was added to the
reaction mixture, and inorganic salts were filtered off. Volatiles
were removed in vacuum, and the solid (0.5 g) was crystallized
twice from a mixture of CH3CN/Et2O to give compound 4b
(0.21 g, 37 %) as dark-red solid. Mp. 223 – 226 °C (decomp.).
3
1H NMR (CDCl3) δ: 0.97 (t, JHH
= 7.0 Hz, 6H,
KBr pellets on
a
Fourier-spectrometer “Magna-IR750”
(Nicolet), resolution 2 cm-1, 128 scans. Melting points were
uncorrected. The starting 3,5-bis(arylidene)4-piperidones 3a-c
were obtained by the known procedures including condensation
of piperidine-4-one with the corresponding aldehydes in glacial
acetic acid in the presence of gaseous hydrogen chloride as
reported in ref. [2a] and had the same physical-chemical
constants as described in literature [2a]. N-Methyl-piperidone
was obtained from Aldrich and used without further purification.
(3E,5E)-3,5-Bis[4-(dimethylamino)benzylidene]-1,1-diethyl-
N(CH2CH2CH3)2), 1.55 (m, 4H, N(CH2CH2CH3)2), 3.05 (s, 12H,
2 N(CH3)2), 3.55 (m, 4H, N(CH2CH2CH3)2), 5.11 (m, 4H, NCH2
3
3
(cyclic), 6.73 (d, JHH = 8.7 Hz, 4H, C6H4), 7.36 (d, JHH = 8.7
Hz, 4H, C6H4), 8.11 (s, 2H, CH=). 13C NMR (CDCl3) δ: 10.47
(N+CH2CH2CH3), 15.68 (N+CH2CH2CH3), 39.88 (NCH3), 59.57
(N+CH2 (cyclic)), 60.14 (N+CH2CH2CH3), 111.87 (C8,C10),
117.65 (C6), 120.28 (CH=C), 133.20 (C7,C11), 144.31 (CH=C),
151.66 (C9), 179.98 (C=O). IR (KBr) ν, cm-1: 2963, 2930, 2873,
1661 (C=O), 1612 (C=C), 1575, 1522, 1436, 1373, 1315, 1278,
1231, 1184, 1167, 1131, 989, 814, 522. Anal. Calcd. for
4-oxopiperidinium iodide (4a).
A mixture of 3,5-bis[4-

734
M. Makarov, I. Odinets, K.Lyssekko, E.Rubalkina, I.Kosilkin, M.Antipin, T. Timofeeva
Vol 45
C29H40IN3O: C, 60.73%; H, 7.03%; N, 7.33%. Found: C,
60.89%; H, 7.04%; N, 7.51%.
(3E,5E)-1-Methyl-3,5-bis(4-fluorobenzylidene)-4-oxopiper-
idinium chloride (5d). N-Methyl-piperidin-4-one (1.02 g, 9
mmol) and 4-fluorobenzaldehyde (2.23 g, 18 mmol) were
dissolved in glacial acetic acid (15 mL). Hydrogen chloride
prepared from ammonium chloride (2.6 g, 48 mmol) was bubbled
through the solution. The reaction solution was allowed to stay at
room temperature for about 40 hours. During this period, the
reaction mixture got crimson color, and the formation of the
precipitate was observed. The precipitate was filtered off and
washed with acetic acid. The light-yellow precipitate was dried in
vacuum at 145 ºC to give pure 5d (2.08 g, 64%). The mother
liquor and the washings were combined, and acetic acid was
removed in vacuum. Acetone (5 mL) was added to the residue,
and yellow powder (0.19 g) was filtered off. Drying of this
powder in vacuum at 145 ºC afforded an additional amount of 5d
(0.16 g). Total yield of 5d was 2.24 g, 69%. Mp. 248 – 251 °C
(3E,5E)-1,1-Dibutyl-3,5-bis[4-(dimethylamino)benzylid-
ene]-4-oxopiperidinium iodide (4c). Using the similar
procedure except the reaction time (see, Table 1) the salt 4c as
dark-red solid complex with KI (0.26 g, 37%) of composition
(4c)9•KI was obtained from 3a (0.36 g, 1 mmol) and iodobutane
(0.92 g, 5 mmol) after double recrystallization from a mixture of
CHCl3/hexane. The mother liquor was evaporated and the
remaining compound was subjected to column chromatography
on silica gel. Elution with a mixture of acetone/CH2Cl2 = 1/1
followed by crystallization afforded an additional amount (0.05
g) of compound (4c)9•KI. Total yield of the complex was 0.31
1
3
g, 44%. Mp. 162 – 165 °C. H NMR (CDCl3) δ: 0.88 (t, JHH
=
3
7.0 Hz, 6H, N(CH2CH2CH2CH3)2), 1.36 (sextet, JHH = 7.0 Hz,
4H, N(CH2CH2CH2CH3)2), 1.46 (m, 4H, N(CH2CH2CH2CH3)2),
3.06 (s, 12H, 2 N(CH3)2), 3.56 (m, 4H, N(CH2CH2CH3)2), 5.11
(m, 4H, NCH2 (cyclic), 6.74 (d, 3JHH = 7.9 Hz, 4H, C6H4), 7.36 (d,
3JHH = 7.9 Hz, 4H, C6H4), 8.11 (s, 2H, CH=). 13C NMR (CDCl3) δ:
13.44 (N+CH2CH2CH2CH3), 19.25 (N+CH2CH2CH2CH3), 23.82
(N+CH2CH2CH2CH3), 39.87 (NCH3), 58.36 (NCH2), 59.54
(NCH2), 111.84 (C8,C10), 117.77 (C6), 120.29 (CH=C), 133.14
(C7,C11), 144.30 (CH=C), 151.63 (C9), 180.11 (C=O). Anal. Calcd.
for (C31H44IN3O)9•KI: C, 60.05%; H, 7.15%; N, 6.78%, I, 22.74%.
Found: C, 60.04%; H, 7.11%; N, 6.65%, I, 22.50%.
1
(decomp). H NMR (DMSO-d6) δ: 2.97 (s, 3H, NCH3), 4.64 (m,
3
3
4H, NCH2 (cyclic)), 7.38 (appeared t, JHH = JFH = 8.8 Hz, 4H,
C6H4), 7.64 (dd, 3JHH = 8.5 Hz, 3JFH = 5.5 Hz, 4H, C6H4), 7.88 (s,
2H, CH=). 19F-{1H} NMR (DMSO-d6) δ: -109.5. 13C NMR
2
(DMSO-d6) δ: 42.36 (NCH3), 53.12 (NCH2), 116.29 (d, C8, JCF
21.0 Hz), 127.05 (CH=C), 130.36 (d, C6, 4JCF 2.9 Hz), 133.60 (d,
3
1
C7, JCF 8.8 Hz), 138.58 (CH=C), 163.15 (d, C9, JCF 250 Hz),
181.55 (C=O). Anal. Calcd. for C20H18ClF2NO: C, 66.39%; H,
5.01%; N, 3.87%. Found: C, 66.24%; H, 5.01%; N, 3.77%.
Compounds 5a-c were obtained from N-methyl-piperidin-4-
one (5.1 mL, 0.044 mol) and 0.088 mol of the corresponding
substituted aldehyde following the procedure for 5d.
(3E,5E)-1,1-Diethyl-3,5-bis(4-fluorobenzylidene)-4-oxo-
piperidinium iodide (4d). A mixture of 3,5-bis(4-fluorobenz-
ylidene)piperidin-4-one (0.46 g, 1.5 mmol), iodoethane (1.18 g,
7.5 mmol) and calcined potassium carbonate (0.43 g, 3.0 mmol)
was stirred in CH3CN (10 mL) for 70 h (19F monitoring). Then
CH2Cl2 was added to the reaction mixture, and inorganic salts
were filtered off. Volatiles components were removed in
vacuum, and the solid was recrystallized from a mixture of
CHCl3/Et2O to give 0.36 g of the complex formed by 4d,
iodoethane, and potassium iodide. Anal. Calcd. for
(C23H24F2INO)10•(C2H5I)4•3KI: C, 47.05%; H, 4.31%; N, 2.31%.
Found: C, 47.08%; H, 4.17%; N, 2.44%. The complex was
added into 10 mL of water, then stirred for 15 min and left under
the water layer for 48 h. After filtration and drying over
phosphorus pentoxide the analytically pure compound 4d was
isolated in 28% (0.21 g) as bright-yellow powder. Mp. 192 - 195
(3E,5E)-3,5-Bis[4-(dimethylamino)benzylidene]-1-methyl-
4-oxopiperidinium chloride (5a). Yield 90 %. Mp. 245 – 248
1
°C (decomp.). H NMR (DMSO-d6) δ: 3.01 (s, 3H, NCH3), 3.04
3
(s, 12H, 2 N(CH3)2), 4.62 (m, 4H, NCH2 (cyclic)), 6.85 (d, JHH
3
= 8.9 Hz, 4H, C6H4), 7.42 (d, JHH = 8.9 Hz, 4H, C6H4), 7.78 (s,
2H, CH=), 11.17 (br. s, N+H).IR (KBr) ν, cm-1: 3012, 2896,
2349, 1674 (C=O), 1608 (C=C), 1561, 1552, 1433, 1367, 1317,
1280, 1235, 1192, 1168, 979, 941, 809, 577, 529. Anal. Calcd.
for C24H29N3O·2HCl: C, 64.28%; H, 6.97%; Cl, 15.81%; N,
9.37%. Found: C, 63.94%; H, 7.06%; Cl, 15.62%; N, 9.28%.
(3E,5E)-3,5-Bis[4-(diethylamino)benzylidene]-1-methyl-4-
oxopiperidinium chloride (5b). Yield 87%. Mp. 233-234 °C
3
(decomp.). 1H NMR (D2O) δ: 1.03 (t, JHH 7.6 Hz, 12H,
3
N(CH2CH3)2), 2.94 (s, 3H, NCH3), 3.57 (q, JHH = 7.6 Hz, 8H,
1
3
°C (decomp). H NMR (CDCl3) δ: 1.19 (t, JHH = 7.2 Hz, 6H,
3
N(CH2CH3)2), 3.70 (q, JHH = 7.2 Hz, 4H, N(CH2CH3), 5.29 (m,
N(CH2CH3)2), 4.65 (br, NCH2 (cyclic) partially overlapped by
3
signal of H2O in D2O), 7.50 (d, JHH = 8.9 Hz, 4H, C6H4), 7.57
3
3
4 H, NCH2 (cyclic)), 7.21 (appeared t, JHH = JFH = 8.5 Hz, 4H,
C6H4), 7.48 (dd, 3JHH = 8.5 Hz, 3JFH = 5.4 Hz, 4H, C6H4), 8.21 (s,
2H, CH=). 19F-{1H} NMR: -109.91 ppm (CDCl3). Anal. Calcd.
for C23H24F2INO: C, 55.77%; H, 4.88%; N, 2.83%. Found: C,
55.79%; H, 4.97%; N, 2.84%.
3
(d, JHH = 8.9 Hz, 4H, C6H4), 8.03 (s, 2H, CH=). IR (KBr) ν,
cm-1: 2967, 2926, 2511, 2458, 1685, 1615, 1575, 1520, 1472,
1431, 1354, 1314, 1278, 1264, 1177, 1158, 977, 818, 568, 511.
Anal. Calcd. for C28H37N3O•2.25HCl: C, 65.47%; H, 7.70%; N,
8.18%. Found: C, 65.52%; H, 7.50%; N, 8.20%.
1-Ethyl-piperidin-4-one. A mixture of piperidone hydrate
hydrochloride (1.08 g, 0.007 mol) and calcinated potassium
carbonate (1.24 g, 0.009 mol) in CH3CN (12 mL) was stirred for
2.5 h. Inorganic salts were filtered off and washed with CH3CN
(4 mL). Filtrate and washings were combined and mixed with
bromoethane (0.80 g, 0.007 mol) and calcinated potassium
carbonate (1.24 g, 0.009 mol). Reaction mixture was stirred for
21 h. Inorganic salts were filtered off and washed with benzene.
The solvent was removed in vacuum; the remaining liquid was
dissolved in benzene and the solution was filtered. Evaporation
of benzene afforded 1-ethyl-piperidin-4-one (0.55 g, 62 %) as
(3E,5E)-1-Methyl-3,5-bis(4-nitrobenzylidene)-4-oxopiper-
idinium chloride (5c). Yield 74%. Mp. 250-251 °C (decomp.).
1H NMR (DMSO-d6) δ: 2.99 (s, 3H, NCH3), 4.70 (s, 4H, NCH2
3
(cyclic)), 7.83 (d, JHH = 8.7 Hz, 4H, C6H4), 8.01 (s, 2H, CH=),
3
8.35 (d, JHH = 8.7 Hz, 4H, C6H4), 11.08 (br. s, N+H). IR (KBr)
ν, cm-1: 3108, 2928, 2450, 1680 (C=O), 1614 (C=C), 1599, 1593
(C=C), 1519 (NO2, νas), 1466, 1414, 1348 (NO2, νs), 1317, 1265,
1170, 1109, 852, 756, 686. Anal. Calcd. for C20H17N3O5•HCl: C,
57.77%; H, 4.36%; Cl, 8.53%; N, 10.11%. Found: C, 57.74%;
H, 4.38%; Cl, 8.68%; N, 10.01%.
1
3
light yellow liquid. H NMR (CDCl3) δ: 1.00 (t, JHH = 7.0 Hz,
3H, NCH2CH3), 2.32 (m, 4H), 2.40 (q, JHH = 7.0 Hz, 2H,
(3E,5E)-1-Ethyl-3,5-bis(4-nitrobenzylidene)-4-oxopiperi-
dinium chloride (5e). N-ethyl-piperidin-4-one (0.70 g, 5.5
mmol) and 4-nitrobenzaldehyde (1.51 g, 10 mmol) were mixed
3
NCH2CH3), 2.61 (m, 4H) (cf. [19]).

May-Jun 2008
N-alkylated 3,5-bis(arylidene)-4-piperidones
735
in glacial acetic acid (25 mL). Hydrogen chloride prepared from
ammonium chloride (3 g, 56 mmol) was bubbled through the
solution. The reaction solution was allowed to stay at room
temperature for approximately 72 hours. The crystals formed
were collected, washed with acetone and dried in air to give 5e
as yellow crystals (0.95 g, 44 %). Mp. 250-251 °C (decomp.).1H
987, 820. Anal. Calcd. for C28H37N3O: C, 77.92%; H, 8.64%; N,
9.74%. Found: C, 78.01%; H, 8.67%; N, 9.64%.
(3E,5E)-1-Methyl-3,5-bis(4-nitrobenzylidene)-piperidin-4-
one (6c). Yield 89 %. Mp. 222 – 225 °C. (lit.: Mp.229 – 231 °C
1
[17]). H NMR (CDCl3) δ: 2.49 (s, 3H, NCH3), 3.79 (s, 4H,
3
NCH2 (cyclic)), 7.53 (d, JHH = 8.9 Hz, 4H, C6H4), 7.83 (s, 2H,
3
CH=), 8.29 (d, 3JHH = 8.9 Hz, 4H, C6H4). IR (KBr) ν, cm-1: 1670
(C=O), 1598, 1589 (C=C, aromatic), 1510 (NO2, νas), 1342
(NO2, νs), 1328, 1314, 1251, 1167, 1106, 980, 928, 861, 850,
802, 757, 688. Anal. Calcd. for C20H17N3O5: C, 63.32%; H,
4.52%; N, 11.08%. Found: C, 63.47%; H, 4.51%; N, 11.04%.
(3E,5E)-1-Ethyl-3,5-bis(4-nitrobenzylidene)piperidin-4-one
(6e). After the solvent was removed in vacuum, the crude
product was recrystallized from a mixture of CH2Cl2/heptane to
give a bright yellow solid 6e in 72 %. Mp. 178 – 183 °C
NMR (DMSO-d6) δ: 1.24 (t, JHH 7.0 Hz, 3H, NCH2CH3), 3.40
(br, NCH2CH3, partially overlapped by signal of H2O in DMSO-
3
d6), 4.64 (m, 4H, NCH2 (cyclic), 7.86 (d, JHH = 8.7 Hz, 4H,
3
C6H4), 8.35 (d, JHH = 8.7 Hz, 4H, C6H4), 8.01 (s, 2H, CH=),
11.13 (s, 1H, N-H). IR (KBr) ν, cm-1: 3104, 2928, 2452, 1685
(C=O), 1617, 1601 (C=C), 1593, 1515 (NO2, νas), 1414, 1341
(NO2, νs), 1319, 1260, 1195, 1116, 1105, 990, 864, 853, 814,
756, 689. Anal. Calcd. for C21H20ClN3O5: C, 58.68%; H, 4.69%;
N, 9.78%. Found: C, 58.61%; H, 4.77%; N, 9.64%.
3
(decomp.). 1H NMR (CDCl3) δ: 1.05 (t, JHH = 7.0 Hz, 3H,
(3E,5E)-1-Methyl-3,5-bis(4-fluorobenzylidene)-piperidin-
4-one (6d). A suspension of 1-methyl-3,5-bis(4-fluorobenzylid-
ene)-4-oxopiperidinium chloride 5d (0.51 g, 1.4 mmol) and
potassium carbonate (1.54 g, 11 mmol) in a mixture of water (10
mL) and CH2Cl2 (15 mL) was stirred for about 3 hours at room
temperature. The yellow organic solution was separated and
dried over Na2SO4. After removal of dichlorometane in vacuum,
and the desired compound 6d (0.45 g, 98%) was obtained as
NCH2CH3), 2.61 (q, 3JHH = 7.0 Hz, 2H, NCH2CH3), 3.80 (m, 4H,
NCH2 (cyclic)), 7.53 (d, JHH = 8.8 Hz, 4H, C6H4), 7.81 (s, 2H,
3
3
CH=), 8.28 (d, JHH = 8.8 Hz, 4H, C6H4). 13C NMR (CDCl3) δ:
12.16 (NCH2CH3), 51.29 (NCH2CH3), 54.07 (NCH2), 123.74
(C8 C10), 130.71 (C7 C11) 134.05 (CH=C), 135.75 (CH=C),
,
,
141.26(C6), 147.48 (C9), 186.36 (C=O). IR (KBr) ν, cm-1: 1679
(C=O), 1600, 1592 (C=C, aromatic), 1513 (NO2, νas), 1346
(NO2, νs), 1310, 1261, 1231, 1172, 1109, 989, 853, 756, 687.
Anal. Calcd. for C21H19N3O5: C, 64.12%; H, 4.87%; N, 10.68%.
Found: C, 64.07%; H, 4.78% N, 10.69%
1
light-yellow powder. Mp. 174 – 177 °C. H NMR (CDCl3) δ:
2.47 (s, 3H, NCH3), 3.76 (m, 4H, NCH2 (cyclic)), 7.11 (appeared
3
t, 3JHH = JFH = 8.6 Hz, 4H, C6H4), 7.37 (dd, 3JHH = 8.6 Hz, 3JFH
=
5.5 Hz, 4H, C6H4), 7.78 (s, 2H, CH=). 19F-{1H} NMR (CDCl3)
X-ray Crystallography. Crystals of 4d suitable for X-ray
diffraction were grown by slow evaporation of CH3CN/Et2O
solution. Crystallographic data for 4d (C23H24F2NOI) at 100K:
crystals (0.40×0.24×0.20 mm) are monoclinic, space group
δ: -110.6 ppm. 13C NMR (CDCl3) δ: 45.70 (NCH3), 56.77
(NCH2), 115.58 (d, C8, C10, 2JCF = 22.0 Hz), 131.17 (d, C6, 4JCF
=
3.7 Hz), 132.17 (d, C7, C11, JCF = 8.8 Hz), 132.49 (CH=C),
135.09 (CH=C), 162.74 (d, C9, 1JCF = 251 Hz), 186.37 (C=O). IR
(KBr) ν, cm-1: 2850, 2782, 1672 (C=O), 1613, 1601 (C=C),
1580, 1509, 1504, 1458, 1411, 1293, 1273, 1232, 1227, 1175,
1160, 1130, 1107, 1086, 1056, 983, 924, 853, 835, 791. Anal.
Calcd. for C20H17F2NO: C, 73.83%; H, 5.27%; N, 4.31%. Found:
C, 73.81%; H, 5.19%; N, 4.35%.
3
P21/c, a= 9.377(2),
b
=
14.511(3), c= 15.742(3) Å,
β=105.560(7)°, V= 2063.5(7) Å3, Z=4 (Z'=1), M= 495.33, dcalc
=
1.594 gcm-3, µ(MoKα)=15.83 cm-1, F(000)= 992. Intensities of
15498 reflections were measured with an APEX II CCD
diffractometer at 100K (λ(MoKα)=0.71072Å, 2θ<59°) and 5469
independent reflections (Rint= 0.0449) were used in the further
refinement. The structure was solved by direct method and
refined by the full-matrix least-squares technique against F2 in
the anisotropic-isotropic approximation. The refinement
converged to wR2= 0.0901 and GOF=0.967 for all independent
reflections (R1=0.0337 was calculated based on F for 4215
observed reflections with I>2σ(I)). All calculations were
performed using SHELXTL PLUS 5.0 [20]. Crystallographic
data (excluding structure factors) for the structures reported in
this paper have been deposited to the Cambridge
Crystallographic Data Centre as supplementary no. CCDC
635654. Copies of the data can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge CB2 1EZ UK
The free bases 6a-c,e were obtained according to the similar
procedure.
(3E,5E)-3,5-Bis[4-(dimethylamino)benzylidene]-1-methyl-
piperidin-4-one (6a). Yield 86 %. Mp. 229 – 232 °C (lit.:
Mp.223 – 225 °C [17]). 1H NMR (CDCl3) δ: 2.48 (s, 3H, NCH3),
2.99 (s, 12H, 2 N(CH3)2), 3.78 (s, 4H, NCH2 (cyclic)), 6.69 (d,
3JHH = 8.9 Hz, 4H, C6H4), 7.32 (d, 3JHH = 8.9 Hz, 4H, C6H4), 7.76
(s, 2H, CH=). 13C NMR (CDCl3) δ: 39.86 (NCH3), 45.60
(NCH3), 57.14 (NCH2 (cyclic)), 111.48 (C8, C10), 123.17 (C6),
128.92 (CH=C), 132.33 (C7, C11), 136.35 (CH=C), 150.38 (C9),
186.26 (C=O). IR (KBr) ν, cm-1: 2941, 1654 (C=O), 1615
(C=C), 1579, 1524 (C=C, aromatic), 1433, 1372, 1310, 1285,
1232, 1163, 1052, 986, 811, 514. Anal. Calcd. for C24H29N3O: C,
76.77%; H, 7.78%; N, 11.19%. Found: C, 76.74%; H, 7.82%; N,
11.14%.
(Fax:
(internat.)
+44-1223/336-033;
E-mail:
deposit
@ccdc.cam.ac.uk).
Biological evaluations. Cell line used for estimation was
A549 - human lung carcinoma cell line. Cells were grown in
RPMI-1640 medium (Sigma-Aldrich, UK) supplemented with
10% fetal bovine serum (FBS, HyClone, USA), 2 mML-
glutamine and gentamicin.
Cells were plated at a density of 2x105 cells/mL in culture
medium with increasing drug concentrations. The compounds
were primary dissolved in dimethylsulphoxide (DMSO) and the
using solutions were in FBS free culture medium. Control
preparations contained similar amounts of DMSO. Plates were
incubated for 48 h at 37oC in a humidified atmosphere
containing 5%CO2. After incubation the percentage survival of
(3E,5E)-3,5-Bis[4-(diethylamino)benzylidene]-1-methyl-
1
piperidin-4-one (6b). Yield 92 %. Mp. 195 – 198 °C. H NMR
3
(CDCl3) δ: 1.18 (t, JHH = 7.0 Hz, 12H, N(CH2CH3)2), 2.49 (s,
3
3H, NCH3), 3.38 (q, JHH = 7.0 Hz, 8H, N(CH2CH3)2), 3.79 (s,
3
4H, NCH2 (cyclic)), 6.66 (d, JHH = 8.9 Hz, 4H, C6H4), 7.32 (d,
3JHH = 8.9 Hz, 4H, C6H4), 7.75 (s, 2H, CH=). 13C NMR (CDCl3)
δ: 12.42 (N(CH2CH3)2), 44.18 (N(CH2CH3)2), 45.76 (NCH3),
57.29 (NCH2 (cyclic)), 110.83 (C8, C10), 122.37 (C6), 128.62
(CH=C), 132.67 (C7, C11), 136.19 (CH=C), 147.88 (C9), 186.35
(C=O). IR (KBr) ν, cm-1: 2968, 1660 (C=O), 1587, 1519, 1432,
1355, 1315, 1288, 1268, 1199, 1179, 1172, 1152, 1075, 1012,

736
M. Makarov, I. Odinets, K.Lyssekko, E.Rubalkina, I.Kosilkin, M.Antipin, T. Timofeeva
Vol 45
[6a] Jobin, C.; Bradham, C.A.; Russo, M.P.; Juma, B.; Narula,
A.S.; Brenner, D.A. Sartor, R.B. J.Immunol., 1999, 163, 3474. [b]
Kumar, S.; Narain, U.; Misra, K. Bioconjugate Chem., 2001, 12, 464. [c]
Ahmad N.; Katiyar, S.K.; Mukhtar H. In Oxidants and antioxidants in
cutaneous biology. Thiele, J.; Elsner, P.; Eds., KARGER, Jena, 2001,
pp.128-139.
[7] Odinets, I. L.; Artyushin, O. I.; Goryunov, E. I.; Lyssenko, K.
A.; Rybalkina, E. Yu.; Kosilkin, I. V.; Timofeeva, T. V.; Antipin, M.
Yu. Heteroatom Chem. 2005, 16, 497.
the cells was recorded. The viable cells were determined by
trypan blue exclusion. Each compound including parent NH-
piperidones 3a-c was examined in triplicate and the IC50 values
were determined graphically. The concentrations of compounds
used were 5x10-5, 10-5, 10-6, 10-7M. Commercially available
Melphalan (Sarcolysin) purchased from Arkelan-Glaxo was
used as a positive control in the assay.
Acknowledgement. Authors are grateful for support from
NIH via RIMI program, grant 1P20MD001104-01 and from
Russian Basic Research Foundation, grant 05-03-32692.
[8] Nesterov, V. N.; Timofeeva, T. V.; Sarkisov, S. S.;
Leyderman, A.; Lee, C. Y.-C.; Antipin, M. Yu. Acta Cryst. 2003, C59,
605-608.
[9] Szakacs, G.; Annerau, J.-P.; Lababidi, S.; Shankavaram, U.;
Arciello, A.; Bussey, K. J.; Reinhold, W.; Guo, Y.; Kruh, G. D.;
Reimers, M.; Weinstein, J. N.; Gottesman, M. M. Cancer Cell 2004, 6,
129.
[10] Youssef, K. M.; El-Sherbeny, M. A. Arch. Pharm. Chem. Lif.
Sci. 2005, 338, 181.
[11] Jia, Z.; Quail, J. W.; Arora V. K.; Dimmock, J. R. Acta Cryst.
1989, C45, 1119.
[12] Jia, Z.; Quail, J. W.; Arora V. K.; Dimmock, J. R. Acta Cryst.
1989, C45, 1117.
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