Selective hydroboration of dieneamines. Formation of hydroxyalkylphenothiazines as MDR modulators

Article abstract of DOI:10.1016/j.bmc.2012.05.065

N-dienylphenothiazines synthesized from tetrazolo[1,5-a]pyridinium salts by treatment with phenothiazine were subjected to catalytic hydrogenation to yield N-butylphenothiazines, whereas transformation of these dienes with borane dimethyl sulfide (BH₃ × Me₂S) resulted in selective hydroboration of one double bond and full reduction of the other double bond to give 2-hydroxybutylphenothiazines. Position of the hydroxyl group was supported by NMR spectroscopy and verified by X-ray analysis. Comparison of MDR modulatory activity of the new derivatives revealed that the hydroxybutyl compounds are promising candidates for development of novel MDR inhibitors.

Full text of DOI:10.1016/j.bmc.2012.05.065

Bioorganic & Medicinal Chemistry 20 (2012) 4258–4270
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Selective hydroboration of dieneamines. Formation
of hydroxyalkylphenothiazines as MDR modulators
Daniella Takács a, Ildikó Nagy a,b, Petra Bombicz a, Orsolya Egyed a, Katalin Jemnitz a, Zsuzsanna Riedl a,
József Molnár c, Leonard Amaral d, György Hajós a,
⇑
a Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary
b Bioblocks Magyarország Kft, Mester u. 5, H-1095 Budapest, Hungary
c Department of Medical Microbiology, University of Szeged, Dóm tér10, H-6720 Szeged, Hungary
d Unidade de Micobacterias, Instituto de Higiene e Medicina Tropical, Universidade de Lisboa, Rua da Junqueira, 96, 1394-008 Lisbon, Portugal
a r t i c l e i n f o
a b s t r a c t
Article history:
N-dienylphenothiazines synthesized from tetrazolo[1,5-a]pyridinium salts by treatment with phenothi-
azine were subjected to catalytic hydrogenation to yield N-butylphenothiazines, whereas transformation
of these dienes with borane dimethyl sulfide (BH3 ꢀ Me2S) resulted in selective hydroboration of one
double bond and full reduction of the other double bond to give 2-hydroxybutylphenothiazines. Position
of the hydroxyl group was supported by NMR spectroscopy and verified by X-ray analysis. Comparison of
MDR modulatory activity of the new derivatives revealed that the hydroxybutyl compounds are promis-
ing candidates for development of novel MDR inhibitors.
Received 24 February 2012
Revised 17 May 2012
Accepted 25 May 2012
Available online 5 June 2012
Keywords:
Dieneamine
Hydroboration
Catalytic hydrogenation
Multidrug resistance
P-gp inhibition
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
the overexpression of multispecific ATP-binding cassette trans-
porters (ABC transporters) of cancer cells is widely regarded as
Multidrug resistance (MDR) modulatory activity of large num-
ber of N-substituted phenothiazines is well known from the litera-
ture for a long time.1,2 Some representative derivatives with such
biological activity are shown in Figure 1. Some other related het-
erocyclic derivatives also exhibited valuable biological activities
and proved to be inhibitors of mitotic kinesin Eg5 and trigger apop-
tosis,3 potential antimicrobial agents,1,4–6 antitumor agents,7 anti-
tubercolotic compounds,8 potential chemotherapeutic agents,9
antioxidants.10
Elaborated syntheses of these compounds include basically two
strategies: (a) alkylation of the phenothiazine ring-nitrogen
atom8,13 followed by functionalization of the alkyl chain, and (b)
ring closure of the appropriately functionalized alkyl-diphenyl-
amine by sulfur to yield the phenothiazine ring.14 Comparison of
activities of some recently synthesized N-alkylphenothiazines15 re-
vealed that the optimal length of the alkyl chain is four.16
The chemotherapy to treat cancer often fails mainly due to tu-
mor resistance that may be either an intrinsic feature of the spe-
cific cancer type or may be acquired during the course of initial
chemotherapy. A limited intratumoral drug disposition due to
the main molecular mechanism of MDR. The majority of clinically
important cases of MDR seems to be the result of overexpression of
three ABC transporters: P-glycoprotein (P-gp, ABCB1), multidrug
resistance-associated protein 1 (MRP1, ABCC1), and breast cancer
resistance protein (BCRP, ABCG2).17 An attractive approach to
overcoming MDR is the inhibition of the pumping action of these
transporters.18 Hundreds of compounds able to inhibit P-glycopro-
tein or MRP1 have been identified. Their structural diversity is al-
most as wide as the diversity of substrates recognized by MDR
transporters. The ability of phenothiazine derivatives to increase
the accumulation of cytotoxic drugs in resistant cancer cells was
discovered as early as 1982. Numerous studies have been per-
formed in order to identify structural features important for phe-
nothiazines to constitute good MDR reversing agents.19
2. Results and discussion
Recognition of a new access to N-dienylphenothiazines (2) by
utilization of the ring opening reaction of tetrazolo[1,5-a]pyridini-
um salts (1) by phenothiazine as a nucleophile20–22 prompted us to
explore the synthetic possibility to variously substituted novel
phenothiazines and to test their biological effectiveness in the area
(Scheme 1).
⇑
Corresponding author.
E-mail addresses: ghajos@chemres.hu, hajos.gyorgy@ttk.mta.hu (G. Hajós).
0968-0896/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmc.2012.05.065

D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
4259
S
N
carried out in good yields (52–98%). Also in this case, the bromo
and chloro atoms at the phenyl substituent were substituted by
hydrogen atom and, thus, both 3a and 3b gave the same phen-
yltetrazolylcarbazole 5a.
S
N
S
N
CF3
N
SCH3
Cl
Because of the low yields experienced in some cases and the
non-desired dehalogenation at the phenyl group, elaboration of an-
other reduction method seemed necessary and, thus, reduction
with borane was decided. In this respect we have shown recently20
that treatment of N-dienylphenothiazines (2) with borane di-
methyl sulfide (BH3 ꢀ Me2S) in abs. THF resulted in formation of
tetrazolo[5,1-f][1,2]azaborinin (7) as a new heterocyclic ring sys-
tem (Scheme 3). As the reaction was interpreted by intermediate
formation of the 2-butylborane 6, modification of the reaction con-
ditions seemed to provide a possibility for formation of fully re-
duced and boron-free products.
Thus, when the reaction of 2 with BH3 ꢀ Me2S in THF was
warmed up to room temperature, methanol was added and the
reaction mixture was stirred at room temperature in the presence
of air for prolonged time. A new spot appeared on the TLC of the
reaction mixture and spectral analysis of this new component re-
vealed formation of 4-(2-(4-chlorophenyl)-2H-tetrazol-5-yl)-1-
(10H-phenothiazin-10-yl)butan-2-ol (8b) in poor yield. As this
compound was obviously result of a hydroboration reaction we
had to assume that an oxidative reaction step took place on the
effect of the areal oxygen. Therefore we have repeated this conver-
sion with addition of hydrogen peroxide and found that the
butanol derivative 8 was formed as main product in acceptable
yield (Scheme 4). In order to check whether the earlier isolated
azaborinin compound 7 is an intermediate in the pathway leading
to 8, two azaborinin derivatives (7i and 7j) were prepared
according to the published procedure20, and these compounds
were then subjected to oxidation by hydrogen peroxide in metha-
nol. As a result, 8h and 8i have been obtained in good yields, which
supported the intermediacy of 7 in the course of the hydroboration
reaction.
CH3
CH3
N
N
N
CH3
CH3
thioridazine
trifluoperazine
chloropromazine
Figure 1. N-substituted phenothiazines as established MDR modulators: chloro-
promazine11, trifluoperazine12, and thioridazine.13
For comparative purposes the tetrazolopyridinium salts (1)
were also reacted with carbazole to provide the analogous
dienylcarbazoles (3). In both groups of dienes (2 and 3) the double
bond attached to the tetrazole ring had, in majority, cis configura-
tion, and trans isomers were observed in special cases only.23
Since the known biologically active compounds contained a sat-
urated alkyl chain at the ring-nitrogen atom of the heterocycles,
reduction of the obtained diene was envisaged. A specific struc-
tural advantage of these target products is the length of the alkyl
chain (4 carbon atoms) which was found to be optimal in a recent
study.16 This synthetic plan would represent an unprecedented ap-
proach to N-alkylphenothiazines. As catalytic hydrogenation of N-
ethenylphenothiazine, in spite of the presence of the sulfur atom,
has been carried out successfully24 to yield the N-ethyl compound,
catalytic hydrogenation of the dienylphenothiazines (2) and die-
nylcarbazoles (3) was tried first.
Both dienes (2 and 3) underwent saturation with catalytic
hydrogenation at room temperature (Scheme 2). As expected—
due to the presence of the sulfur atom—the yields strongly varied
(10–99%) in case of reduction of 2. Furthermore, the bromo and
chloro atoms at the phenyl substituent (i.e. with 2b and 2f) also
underwent hydrogenation simultaneously with reduction of the
diene moiety and, thus, both of these dienes resulted in formation
of unsubstituted phenyl rings (4a and 4e, respectively). In contrast
to reduction of 2, hydrogenation of the dienylcarbazoles (3) was
Furthermore, thorough analysis of the reaction mixture ob-
tained with the synthesis of 8i revealed the presence of two
R
R
S
N
Q
N
N
N
N
H
Q
N
N
N
N
N
N
N
S
H
N
N
BF4
N
N
R
2
3
1
entry
Q
R
entry
R
entry
R
a
b
c
H
H
Br
Cl
a
b
c
a
b
c
Br
Cl
Br
Cl
OMe
H
H
OMe
OMe
Me
F
d
e
f
Me
F
d
Me
d
e
H
CF3
Br
g
CF3
OMe
OMe
2-methyl-1,3-
dioxolane
h
i
j
Cl
Cl
Br
OMe
Scheme 1. Ring opening of tetrazolo[1,5-a]pyridinium salts (1) by phenothiazine and carbazole to dienylphenothiazines (2) and dienylcarbazoles (3), respectively.

4260
D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
The assignment of 1H, 13C, 15N resonances for compounds 8i, 9
Q
and 10 followed the regular procedure: collection and analysis of
S
1D (1H, 13C, selective 1D-TOCSY, selective 1D-NOESY) and
Selcat Q-6
Pd/C (10%) / H
2
N
through-bond correlation (1H–13C gHSQC, 1H–13C gHMBC, 1H–15
N
2
N
N
MeOH/ CH Cl
2
abs. TEA
RT, 1 day
2
N
gHMBC) data. The exact position of OH groups was determined
from HMBC measurements. The OH–C2 and OH–C3 crosspeaks in
the gHMBC spectra of 8i and 9 suggested location of the OH substi-
tuent at C2 carbon. A further OH group could be identified at C4
carbon in compound 10, according to the OH–C4 and OH–C3 cross
peaks in the corresponding HMBC spectrum.
N
4
starting
compound
R'
entry
Q
R'
The compound 4-(2-(4-bromophenyl)-2H-tetrazol-5-yl)-1-
(10H-phenothiazin-10-yl)butan-2-ol (8a), which crystallizes in
the triclinic crystal system in the centrosymmetric P-1 space
group, was subjected to structural analysis. The structure was
determined by single crystal X-ray diffraction using a Rigaku R-
a
2a, 2b
2c
H
H
H
b
c
OMe
Me
F
2d
H
H
2e
d
e
Axis Rapid diffractometer with MoKa radiation at room tempera-
CF3
2f
ture (Table 1, Supplementary data). It is an ordered structure, there
is one molecule of 8a in the asymmetric unit (Fig. 2). The unit cell
contains no residual solvent accessible void. The packing coeffi-
cient is 67.3%.
The bond lengths around the heteroatoms in the molecule are
listed in Table 2 (Supplementary data). The angles of the aromatic
rings according to the assignment in Figure 2 are A-B: 6.50(12)o, C-
D: 46.24(13)o, A–C: 20.50(12)o, A–D: 66.66(11)o, B–C: 14.40(13)o
and B–D: 60.64(13)o. The conformation of the molecule is stabi-
lized by weak intramolecular interactions, one C–Hꢁ ꢁ ꢁO, and four
C–Hꢁ ꢁ ꢁN hydrogen bond occurs (Table 3, Fig. 5, Supplementary
data). The intramolecular distance of the B and C ring centroids
is 3.946(2) Å.
H
CF3
2g
f
OMe
2-methyl-1,3-
dioxolane
g
2h
OMe
N
N
Selcat Q-6
Pd/C (10%)/ H
2
N
N
3
N
MeOH/ CH Cl
2
abs. TEA
RT, 1 day
2
5
Hydroboration of butadienes has only sparingly been studied
earlier, most of these results were born in laboratory of H. C.
Brown. Thus, an early paper reported that some butadienes yield
1,3- and 1,4-diols26, monohydroboration of cyclic butadienes gave
allylic and homoallylic products.27 In some special cases monohyd-
roboration was experienced with retention of one of the double
bonds.28 To the best of our knowledge, hydroboration of a 1,3-
diene to a saturated 2-butanol has not yet been reported in the
literature.
R'
starting
entry
R'
H
compound
3a, 3b
3c
a
b
c
OMe
Me
3d
The observed selectivity, that is, formation of the 2-butanol
derivative 8 is obviously due to the presence of the electron releas-
ing tertiary amine moiety provided by the nitrogen atom of the
phenothiazine ring. Product of the other possible hydroboration
(4-butanol) was not detected, only butan-2,4-diol (10) was found
in traces as result of an excessive oxidation.
The hydroboration reaction of dienylphenothiazines proved to
be a general approach to N-phenothiazinylbutan-2-ols and, thus,
a great variety of variously substituted products (8a–i) have been
synthesized in good to excellent yields (Scheme 4).
Two further synthetic modifications have been carried out in or-
der to extend the structural variation of the new alkylphenothia-
zines and alkylcarbazoles:
(a) The above discussed hydroboration reaction was success-
fully applied also for one of the dienylcarbazoles (3c). Transforma-
Scheme 2. Catalytic hydrogenation of dienylphenothiazines (2) and dienylcarbaz-
oles (3).
additional compounds as side-products: the sulfoxide derivative 9
was formed in 25% yield, whereas the dihydroxy compound 10 was
also detected in traces (6%). NMR spectra of these compounds re-
veal that both have been formed as diastereomeric mixtures. For-
mation of these minor products is clearly result of the
subsequent oxidation steps.
Even if our recent study20 on the borazine ring system showed
that the boron atom attached to position 2 of the butyl chain and,
consequently, introduction of the hydroxyl group can be expected
at this position, a firm determination of the structure of 8 seemed
of interest. To this end, NMR structure elucidation and X-ray anal-
ysis have been carried out.
R
R
4'
3'
1' 2'
BH3xMe2S
3"
2
3
Q
4"
4a"
S
abs. THF
N
N
Q
N
2"
1"
2
N
N
N
N
1
4
0°C
RT
N
5"
H2B
8a
8
10a"
5
S
BH2
2
10"
5a"
7
N
6"
7"
N
4
6
9a"
9"
1
3
8"
7
6
Scheme 3. Formation of tetrazolo[5,1-f][1,2]azaborinin (7) from dienylphenothiazines (2).

D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
4261
1. BH3xMe2S
abs. THF, Ar,
0°C RT
Q
2. MeOH
2
S
10 % NaOH
30 % H2O2 (24 h)
OH
2
BH3xMe2S
N
N
N
abs. THF, Ar,
0°C RT
4
1
3
N
N
7
8
R
R
Q
entry
Q
R
a
b
c
7i
7j
Br
H
H
Br
Cl
Cl
Cl OMe
H
OMe
d
e
Me
F
H
H
CF3
CF3
f
Br
g
OMe
Br
h
i
Cl
Cl
OMe
Cl
OH
Cl
OH
O
S
S
OH
N
N
N
N
N
N
N
N
N
N
10
9
OMe
OMe
Scheme 4. Hydroboration reaction of dienylphenothiazines.
Figure 2. The ORTEP diagram of 8a at 50% probability level with atomic labels and ring assignment.25
tion of this compound with BH3 ꢀ Me2S gave the carbazole-
containing 2-butanol (11) in modest yield (33%) (Scheme 5).
(b) As the new alkylphenothiazines and alkylcarbazoles dis-
cussed here contained a tetrazolylbutyl chain whereas in most of

4262
D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
1. BH xMe S/ abs. THF
3
2
N
Ar, 0°C
RT, 1 day
OH
N
N
N
N
2. MeOH, NaOH (10%),
H O (30%),
N
N
N
2
2
N
0°C
RT, 1 day
33%
N
OMe
3c
11
OMe
Scheme 5. Hydroboration of dienylcarbazole (3c).
the earlier established MDR inhibitory compounds (Fig. 1) a propyl
chain attached to the ring-nitrogen atom of the heterocycle, syn-
thesis of a tetrazolylpropylphenothiazine seemed also of interest.
This has been realized as shown in Scheme 6.
The tetrazolylacrolein derivative 12 described by us re-
cently29,30 served proper starting compound for this purpose: its
reaction with phenothiazine and NBS gave the acylphenothiazine
13 which, under the hydroboration reaction underwent reduction.
Most interestingly, in this case the full reduction of the propanone
chain occurred and the product (14) did not contain any OH group
in the alkyl chain.
3. Biological evaluation. Determination of P-gp inhibitor
potency of compounds
Figure 6. Modulation of intracellular RH 123 accumulation in primary rat
hepatocytes cultured for 4 days.
Rhodamin 123 (RH 123) accumulation studies were performed
to characterize the effect of some selected compounds (2c, 4b, 8c,
11, 14) on P-gp dependent transport activity in primary rat hepa-
tocyte cultures.
tion in a concentration dependent manner; however, did not reach
the efficacy of verapamil. The other compounds did not show sig-
nificant P-gp inhibitory potential, though some difference could
have been observed.
2c and 14 did not increase the intracellular RH 123 accumula-
tion at all and, moreover, in the presence of 14 a slight decrease
was observed. 4b slightly enhanced the dye concentration, not
RH 123, a lipophilic cation, a typical P-gp substrate is a subject
to a P-gp dependent extrusion through the plasma membrane. Due
to its fluorescence, dye levels can easily be measured in cell ex-
tracts and accumulation can be observed in intact cells. RH 123
accumulation in cells and efflux from cells is often used to measure
P-gp dependent transport activity. High intracellular steady state
accumulation of the dye is interpreted of low P-gp activity, and
vice versa. Accordingly, inhibition of P-gp enzymes results in a de-
creased efflux of the dye, subsequently in an increased accumula-
tion level. Verapamil, a known P-gp inhibitor was used as a positive
control.31
more than by 20% of the control, even at 100 lM. The inhibitory
potential of the compounds measured showed the following order:
14 < 2c < 4b < 11 < 8c < verapamil. The presence of the 2-butanol
chain seemed to be essential in regard to the P-gp modulator po-
tency of the new alkylphenothiazines. The lack of the OH group
(4b) significantly decreased the rate of inhibition, while substitu-
tion of 2-butanol chain with an unsaturated dienyl (2c) or with a
shorter propyl chain (14) resulted in the complete loss of activity.
Probably, the phenothiazine part of the molecule also takes part in
the interaction with P-gp, as the carbazole derivative (11) showed
much less inhibitory potential.
Cells were loaded with 5 lM RH 123 for 30 min, than incubated
in the absence (control, with 0.1% DMSO) or presence of modula-
tors for 3 h. Data represent mean values S.D. of three experiments
performed in triplicate. Dye accumulation in control cells set to
100%.
Results are summarized in Fig. 6. At first, all compounds were
applied at 100 lM concentration. Then, if a derivative at 100 lM
increased RH 123 accumulation more than twofold of the control,
the concentration dependence of the inhibition was also measured.
8c proved to be the most effective P-gp inhibitor among the com-
pounds measured. It increased the intracellular RH 123 concentra-
4. Conclusions
As a result of our findings, a new convenient synthetic pathway
to a large variety of N-alkyl and hydroxyalkylphenothiazines and
O
1. NBS/ CCl
S
4
1. BH xMe S/ abs. THF
N
N
3
2
O
0°C
RT, 2.5 h
N
N
N
N
2.
N
N
S
N
N
N
N
N
H
2. MeOH, RT, 4 days
20%
S
N
N
toluene,
reflux, 3 h
34%
OMe
12
13
14
OMe
OMe
Scheme 6. Synthetic pathway to a N-tetrazolylpropylphenothiazine derivative.

D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
4263
related carbazoles has been elaborated by utilization of the ob-
served selective hydroboration of the parent dienophenothiazines.
Comparison of the biological tests revealed that the presence of the
hydroxyl group is significantly increases the MDR inhibitory prop-
erty of these compounds and, thus, can be regarded as a valuable
area for discovery of clinically useful new MDR modulators. Fur-
ther structural modifications of these derivatives as well as biolog-
ical evaluation is in progress.
ture have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication number CCDC 862636.
5.3. Method for determination of P-gp inhibitor properties
Hepatocytes were prepared from male Wistar rats (200–250 g)
(Charles River, Budapest) by two-step, in situ liver collagenase per-
fusion according to the method of Seglen.35 Cell viability (>90%)
was determined by trypan blue exclusion. All procedures were ap-
proved by the Institutional Animal Care and Use Committee. Hepa-
tocytes were plated at a density of 1.9 ꢀ 105 cells/cm2 in 24-well
plates precoated with rat tail collagen in Williams Medium E con-
taining 5% of fetal calf serum, 100 nM insulin, 0.1 mg/ml gentami-
cin, 30 nM Na2SeO3, and 0.1 M dexamethasone. Calf serum was
present for the first 24 h then omitted. Cells were maintained at
37 °C in a humidified atmosphere of 95% air-5% CO2. 1 h after plat-
ing, and every day thereafter the medium was changed to Williams
Medium E supplemented with glucagon, insulin, gentamicin, dexa-
methasone, Na2SeO3. RH 123 accumulation experiments were per-
5. Experimental part
5.1. General methods
Melting points were determined on a Büchi apparatus and are
uncorrected. The IR spectra were recorded on a Thermo Nicolet
Avatar 320 FT-IR spectrometer. NMR experiments were carried
out on 300 MHz (for 1H), 400 MHz (for 1H) and 600 MHz (for 1H)
Varian NMR SYSTEM spectrometers by using 5 mm direct detec-
tion 15N–31P/{1H–19F} probes equipped with Z pulse field gradient.
Measurements were performed at +25 °C in CDCl3 or DMSO. 1H and
13C NMR spectra are referenced to residual solvent signals. 15N
shifts are referenced to CH3NO2 (90% in CDCl3) chemical shift stan-
dard. The elemental analysis has been carried out with an Elemen-
tar Vario EL III apparatus (at the Analytical Laboratory for Organic
Chemistry, Research Centre for Natural Sciences, Hungarian Acad-
emy of Sciences, H-1025 Budapest, Pusztaszeri út 59). Chromato-
graphic separations were carried out on silica gel (60 H, Merck).
Reactions were monitored with Merck silica gel 60 F254, TLC plates
(0.25 mm thickness). All the chemicals and solvents were used as
supplied.
formed at 4 days after plating. Cells were preloaded with 5 aM RH
123 in Williams’ Medium E for 30 min and then washed three
times with ice cold Hanks Balaced Salt Solution (HBSS) and incu-
bated with RH 123 free Williams’ Medium E complemented with
the inhibitors or the vehicle as control (0.1% DMSO), respectively
for 3 h. Subsequently, cells were washed with ice cold HBSS and
the cells were lysed with 0.5% of Triton X100/HBSS. The intracellu-
lar RH 123 concentration was measured fluorimetrically at 519/
538 nm.
5.3.1. General procedure for preparation of tetrazolyldienyl-
phenothiazines (2a–j)
To a mixture of sodium hydride suspension (60%, 0.26 g,
6.67 mmol) and phenothiazine derivative in abs. THF (50 cm3)
was added the appropriate 3-aryltetrazolo[1,5-a]pyridin-4-ium
tetrafluoroborate (1) in portions over 20 min, and the mixture
was stirred at room temperature for 2 days. After evaporation of
the reaction mixture, the residue was dissolved in a 1:1 mixture
of EtOAc:water (50 cm3) and the solid product was filtered off.
The aqueous mother liquor was extracted with EtOAc (thrice)
and the organic phase was dried over anhydrous Na2SO4, filtered
and evaporated. The combined organic solvent was evaporated,
the residue was washed with diethyl ether then it was recrystal-
lized from ethyl acetate – unless otherwise stated - to give the
product.
5.2. Single crystal data, data collection and structure refinement
for 8a
Crystal data for 8a: C23H20BrN5OS, Fwt.: 494.41, Colorless, col-
umn, size: 0.50 ꢀ 0.25 ꢀ 0.13 mm, triclinic, space group P-1,
a = 6.3137(13) Å, b = 11.196(3) Å, c = 15.972(4) Å,
a
= 90.96(1)°,
Å3,
Z = 2,
b = 97.645(9)°,
c
= 103.294(9)°,
V = 1087.7(4)
F(000) = 504, Dx = 1.510 mg/m3,
l
= 2.012 mmꢂ1
.
A crystal of 8a was mounted on a loop. Cell parameters were
determined by least-squares using 6535 (3.105° 6 h 6 35.582°)
reflections. Intensity data were collected on an R-Axis Rapid dif-
fractometer (graphite monochromator
Mo-K
a
radiation,
k = 0.71073 Å) at 293(2) K in the range 3.11° 6 h 6 27.48°. A total
of 48448 reflections were collected of which 4983 were unique
5.3.2. 10-((1E,3Z)-4-(2-(4-Bromophenyl)-2H-tetrazol-5-yl)buta-
1,3-dien-1-yl)-10H-phenothiazine (2a)
[R(int) = 0.0324, R(r) = 0.0170]; intensities of 3734 reflections
were greater than 2
r
(I). Completeness to h = 0.999. Empirical
This compound was obtained from 3-(4-bromophenyl)-tetraz-
olo[1,5-a]pyridin-4-ium tetrafluoroborate (1a, 2.00 g, 5.51 mmol)
and phenothiazine (1.21 g, 6.06 mmol) as yellow crystals, 1.98 g
(76%).14
absorption correction was applied to the data (the minimum and
maximum transmission factors were 0.4329 and 0.7800).
The structure was solved by direct methods.32 Neutral atomic
scattering factors are taken from the International Tables for X-
ray Crystallography.33 Anisotropic full-matrix least-squares refine-
ment32,34 on F2 for all non-hydrogen atoms yielded R1 = 0.0387 and
5.3.3. 10-((1E,3Z)-4-(2-(4-Chlorophenyl)-2H-tetrazol-5-yl)buta-
1,3-dien-1-yl)-10H-phenothiazine (2b)
wR2 = 0.0877 for 1332 [I > 2r(I)] and R1 = 0.0573 and
This compound was obtained from 3-(4-chlorophenyl)-tetrazol-
o[1,5-a]pyridin-4-ium tetrafluoroborate (1b, 1.75 g, 5.51 mmol)
and phenothiazine (1.21 g, 6.06 mmol) as yellow crystals, 1.91 g
(81%).14
wR2 = 0.0953 for all (4983) intensity data, (number of parame-
ters = 283, goodness-of-fit = 1.045, the maximum and mean shift/
esd is 0.001 and 0.000). The maximum and minimum residual elec-
tron density in the final difference map was 0.339 and
ꢂ0.360e.Åꢂ3
.
The weighting scheme applied was w = 1/
[r
2(Fo2)+(0.0401P)2 + 0.4050P], where P = (Fo2+2Fc2)/3. Hydrogen
5.3.4. 10-((1E,3Z)-4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-
yl)buta-1,3-dien-1-yl)-10H-phenothiazine (2c)
This compound was obtained from 3-(4-methoxyphenyl)-
tetrazolo[1,5-a]pyridin-4-ium tetrafluoroborate (1c, 1.73 g,
5.51 mmol) and phenothiazine (1.21 g, 6.06 mmol) as yellow-
brown crystals, 1.73 g (74%).14
atomic positions were located in difference maps. Hydrogen atoms
were included in structure factor calculations but they were not re-
fined. The isotropic displacement parameters of the hydrogen
atoms were approximated from the U(eq) value of the atom they
were bonded to. Crystallographic data for the above crystal struc-

4264
D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
5.3.5. 10-((1E,3Z)-4-(2-(p-Tolyl)-2H-tetrazol-5-yl)buta-1,3-dien-
1-yl)-10H-phenothiazine (2d)
This compound was obtained from 3-(p-tolyl)-tetrazolo[1,5-
a]pyridin-4-ium tetrafluoroborate (1d, 1.64 g, 5.51 mmol) and phe-
nothiazine (1.21 g, 6.06 mmol) to give yellow crystals, 1.83 g
(81%).14
5.3.10. 10-((1E,3Z)-4-(2-(4-Bromophenyl)-2H-tetrazol-5-
yl)buta-1,3-dien-1-yl)-2-chloro-10H-phenothiazine (2i)
This compound was obtained from 3-(4-bromophenyl)-tetraz-
olo[1,5-a]pyridin-4-ium tetrafluoroborate (1a, 2.00 g, 5.51 mmol)
and 2-chlorophenothiazine (1.42 g, 6.07 mmol) as yellow crystals,
1.54 g (55%); mp 179–181 °C; (Found: C, 54.29; H, 2.97; N, 13.76;
C
23H15BrClN5S requires C, 54.10; H, 3.00; N, 13.39%); mmax (KBr)/
5.3.6. 10-((1E,3Z)-4-(2-(4-Fluorophenyl)-2H-tetrazol-5-yl)buta-
1,3-dien-1-yl)-10H-phenothiazine (2e)
cmꢂ1: 3087, 2921, 1620, 1583 and 995; 1H NMR (300 MHz; CDCl3)
d (ppm): 6.23 (1H, d, J = 11.4 Hz), 6.62 (1H, t, J = 11.4 Hz), 7.14–7.26
(5H, m), 7.32–7.38 (2H, m), 7.50–7.58 (2H, m), 7.62–7.66 (2H, m),
7.93–7.96 (2H, m); 13C NMR (75 MHz; CDCl3) d (ppm): 104.1,
106.6, 121.0 (2C), 122.3, 122.6, 123.3, 125.7, 125.8, 127.6, 128.2,
128.8, 129.1, 130.2, 132.7 (2C), 133.3, 135.7, 136.3, 140.5, 141.2,
142.5, 164.6; m/z (EI) [M+H]+: 510.10 (C23H15BrClN5S requires
508.82).
This compound was obtained from 3-(4-fluoro)-tetrazolo[1,5-
a]pyridin-4-ium tetrafluoroborate (1e, 1.64 g, 5.51 mmol) and phe-
nothiazine (1.21 g, 6.06 mmol). Recrystallization from acetonitrile
gave yellow crystals, 1.30 g (57%); mp 175–177 °C; (Found: C,
66.45; H, 3.57; N, 16.56; C23H16FN5S requires C, 66.81; H, 3.90;
N, 16.94%); mmax (KBr)/cmꢂ1: 3089, 3063, 1623, 1512 and 995; 1H
NMR (300 MHz; CDCl3) d (ppm): 6.19 (1H, d, J = 11.1 Hz), 6.63
(1H, dd, J = 11.4, 11.1 Hz), 7.15–7.23 (5H, m), 7.30–7.36 (4H, m),
7.54 (2H, m), 7.66 (1H, dd, J = 13.2, 11.4 Hz), 8.01 (2H, m); 13C
NMR (75 MHz; CDCl3) d (ppm): 103.5, 105.8, 116.4 (d, 2JC,F = 21 Hz),
121.4 (d, 3JC,F = 9 Hz), 122.4 (2C), 125.5 (2C), 127.4 (2C), 128.1 (2C),
130.5 (2C), 133.1, 136.6, 141.1, 141.5 (2C), 162.7 (d, 1JC,F = 248 Hz),
164.8; m/z (EI) [M+H]+: 414.20 (C23H16FN5S requires 413.11).
5.3.11. 2-Chloro-10-((1E,3Z)-4-(2-(4-methoxyphenyl)-2H-
tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-phenothiazine (2j)
This compound was obtained from 3-(4-methoxyphenyl)-
tetrazolo[1,5-a]pyridin-4-ium tetrafluoroborate (1c, 2.00 g, 6.35
mmol) and 2-chlorophenothiazine (1.64 g, 7.00 mmol) as yellow-
brown crystals, 1.69 g (59%).16
5.3.12. General procedure for preparation of tetrazolyldienyl-
carbazoles (3a–d)
5.3.7. 10-((1E,3Z)-4-(2-(4-Bromophenyl)-2H-tetrazol-5-yl)buta-
1,3-dien-1-yl)-2-(trifluoromethyl)-10H-phenothiazine (2f)
This compound was obtained from 3-(4-bromophenyl)-tetraz-
olo[1,5-a]pyridin-4-ium tetrafluoroborate (1a, 2.00 g, 5.51 mmol)
and 2-(trifluoromethyl)-10H-phenothiazine (1.62 g, 6.06 mmol)
as yellow crystals, 2.27 g (76%); mp 175–180 °C; (Found: C,
53.44; H, 2.84; N, 12.57; C24H15BrF3N5S requires C, 53.15; H,
2.79; N, 12.91%); mmax (KBr)/cmꢂ1: 3374, 2361, 1623, 1585 and
994; 1H NMR (300 MHz; CDCl3) d (ppm): 6.24 (1H, d, J = 11.4 Hz),
6.40 (1H, t, J = 11.4 Hz), 7.15–7.43 (6H, m), 7.56–7.72 (5H, m),
7.90 (2H, m); 13C NMR (75 MHz; CDCl3) d (ppm): 104.4, 106.9,
To a mixture of sodium hydride suspension (60%, 0.26 g,
6.67 mmol) and carbazole (1.01 g, 6.06 mmol) in abs. THF
(50 cm3) was added the appropriate 3-aryltetrazolo[1,5-a]pyri-
din-4-ium tetrafluoroborate (1, 5.5 mmol) in portions over
20 min, and the mixture was stirred at room temperature for
2 days. After evaporation of reaction mixture the residue was dis-
solved in a 1:1 mixture of EtOAc:water (50 cm3), the solid product
was filtered off and washed thrice with diethyl ether. The products
were isolated after recrystallization from the given solvent.
3
3
118.7 (q, JC,F = 4 Hz), 121.0 (2C), 122.1 (q, JC,F = 4 Hz), 122.7,
1
5.3.13. 9-((1E,3Z)-4-(2-(4-Bromophenyl)-2H-tetrazol-5-yl)buta-
1,3-dien-1-yl)-9H-carbazole (3a)
123.0, 124.5 (q, JC,F = 270 Hz), 126.0, 127.8, 128.3, 128.4, 129.5
2
(q, JC,F = 30 Hz), 132.6 (2C), 135.2, 135.7, 135.8, 136.1, 140.3,
140.6, 142.2, 164.6; m/z (EI) [M+H]+: 542.00 (C24H15BrF3N5S re-
This compound was obtained from 3-(4-bromophenyl)-tetraz-
olo[1,5-a]pyridin-4-ium tetra-fluoroborate (1a, 2.00 g, 5.5 mmol).
Recrystallization from dimethyl formamide/ hexane gave yellow
crystals, 1.5 g (62%); mp 201–206 °C; (Found: C, 62.18; H, 3.16;
N, 15.81; C23H16BrN5 requires C, 62.46; H, 3.65; N, 15.83%); mmax
(KBr)/cmꢂ1: 3351, 3045, 1635, 1497 and 995; 1H NMR (300 MHz;
CDCl3) d (ppm): 6.54 (1H, d, J = 11.4 Hz, H4), 6.87 (1H, dd,
J = 11.7, 11.4 Hz, H3), 7.37 (2H, m, H300 + H600), 7.53 (2H, m,
H200 + H700), 7.65–7.74 (3H, m, H1 + H30 + H50), 7.92 (2H, d,
J = 8.1 Hz, H400 + H500), 8.08–8.14 (4H, m, H20 + H60 + H100 + H800),
8.35 (1H, dd, J = 14.1, 11.7 Hz, H2); 13C NMR (75 MHz; CDCl3) d
(ppm): 110.7 (C2), 111.1 (C100 + C800), 114.0 (C4), 120.4
(C300 + C600), 121.0 (C400 + C500), 121.7 (C20 + C60), 123.4 (C40), 124.9
(C4a00 + C5a00), 126.6 (C200 + C700), 130.9 (C3), 132.9 (C30 + C50),
135.5 (C1), 135.8 (C10), 139.1 (C8a00 + C9a00), 164.5 (Ctetrazole); m/z
(EI) [M+H]+: 442.20 (C23H16BrN5 requires 441.06).
quires 541.02).
5.3.8. 10-((1E,3Z)-4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-
yl)buta-1,3-dien-1-yl)-2-(trifluoromethyl)-10H-phenothiazine
(2g)
This compound was obtained from 3-(4-methoxyphenyl)-tet-
razolo[1,5-a]pyridin-4-ium
tetrafluoroborate
(1c,
1.73 g,
5.51 mmol) and 2-(trifluoromethyl)-10H-phenothiazine (1.62 g,
6.06 mmol) as yellow crystals, 1.06 g (39%).16
5.3.9. 10-((1E,3Z)-4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-
yl)buta-1,3-dien-1-yl)-2-(2-methyl-1,3-dioxolan-2-yl)-10H-
phenothiazine (2h)
This compound was obtained from 3-(4-methoxyphenyl)-
tetrazolo[1,5-a]pyridin-4-ium tetrafluoroborate (1c, 2.00 g,
6.61 mmol) and 2-(2-methyl-1,3-dioxolan-2-yl)-10H-phenothia-
zine (2.00 g, 7.00 mmol) as yellow crystals, 2.97 g (91%); mp
200–203 °C; (Found: C, 65.44; H, 4.99; N, 13.46; C28H25N5O3S re-
quires C, 65.74; H, 4.93; N, 13.69%); mmax (KBr)/cmꢂ1: 3092, 2993,
1622, 1514 and 1033; 1H NMR (300 MHz; CDCl3-DMSO; Me4Si) d
(ppm): 1.64 (3H, s), 3.79–4.02 (7H, m), 6.15 (1H, d, J = 10.8 Hz),
6.65 (1H, dd, J = 11.4, 10.8 Hz), 7.00 (2H, m), 7.17–7.68 (9H, m),
7.91 (2H, m); 13C NMR (75 MHz; CDCl3-DMSO; Me4Si) d (ppm):
27.9, 56.2, 64.7 (2C), 103.9, 105.6, 108.4, 110.0, 115.4 (2C), 119.7,
121.6, 121.9, 123.1, 126.3, 128.3 (2C), 128.5, 129.3, 130.0, 130.3,
137.3, 141.4, 141.9, 144.4, 160.7, 164.7; m/z (EI) [M+H]+: 512.40
(C28H25N5O3S requires 511.17).
5.3.14. 9-((1E,3Z)-4-(2-(4-Chlorophenyl)-2H-tetrazol-5-yl)buta-
1,3-dien-1-yl)-9H-carbazole (3b)
This compound was obtained from 3-(4-chlorophenyl)-3H-
tetrazolo[1,5-a]pyridin-4-ium tetrafluoroborate (1b, 1.75 g,
5.5 mmol). Recrystallization from dimethyl formamide/MeOH gave
yellow crystals, 1.34 g (61%); mp 198–203 °C; (Found: C, 69.28; H,
3.67; N, 17.59; C23H16ClN5 requires C, 69.43; H, 4.05; N, 17.60%);
mmax (KBr)/cmꢂ1: 3045, 1635, 1498, 1454 and 997; 1H NMR
(300 MHz; CDCl3) d (ppm): 6.55 (1H, d, J = 11.1 Hz), 6.87 (1H, dd,
J = 12.0, 11.1 Hz), 7.37 (2H, t, J = 8.1 Hz), 7.51–7.59 (4H, m), 7.68
(1H, d, J = 14.1 Hz), 7.92 (2H, d, J = 8.1 Hz), 8.08–8.11 (2H, m),
8.18–8.21 (2H, m), 8.35 (1H, dd, J = 14.1, 11.1 Hz); 13C NMR

D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
4265
(75 MHz; CDCl3) d (ppm): 110.7 (2C), 111.1, 114.0, 114.4, 120.3
(2C), 120.7 (2C), 121.1 (2C), 124.0, 126.2 (2C), 130.0 (2C), 131.3,
135.5, 135.6, 139.2, 140.5 (2C), 164.0; m/z (EI) [M+H]+: 398.10
(C23H16ClN5 requires 397.11).
122.7 (2C), 125.5 (2C), 127.4 (2C), 127.7 (2C), 129.7, 129.8 (2C),
137.1, 145.5 (2C), 166.9; m/z (EI) [M+H]+: 400.20 (C23H21N5S re-
quires 399.15).
The same product (4a) was also obtained by the following
transformations: hydrogenation of 10-((1E,3Z)-4-(2-(4-chloro-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-phenothiazine
(2b): 0.08 g (43%).
5.3.15. 9-((1E,3Z)-4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-
yl)buta-1,3-dien-1-yl)-9H-carbazole (3c)
This compound was obtained from 3-(4-methoxyphenyl)-
tetrazolo[1,5-a]pyridin-4-ium tetrafluoroborate (1c, 1.73 g,
5.5 mmol). Recrystallization from dimethyl formamide/MeOH gave
yellow crystals, 1.37 g (63%); mp 183–186 °C; (Found: C, 73.22; H,
4.50; N, 17.81; C24H19N5O requires C, 73.27; H, 4.87; N, 17.80%);
mmax (KBr)/cmꢂ1: 3325, 1639, 1514, 1453 and 999; 1H NMR
(300 MHz; CDCl3) d (ppm): 3.88 (3H, s), 6.52 (1H, d, J = 11.4 Hz),
6.80 (1H, t, J = 11.4 Hz), 7.05 (2H, d, J = 7.5 Hz), 7.34 (2H, t,
J = 7.5 Hz), 7.51 (2H, t, J = 7.5 Hz), 7.62 (1H, d, J = 14.1 Hz), 7.90
(2H, d, J = 7.5 Hz), 8.05–8.15 (4H, m), 8.33 (1H, dd, J = 14.1,
11.4 Hz); 13C NMR (75 MHz; CDCl3) d (ppm): 55.7, 110.0, 111.1
(2C), 114.1, 114.7 (2C), 120.3 (2C), 121.2 (2C), 121.6 (2C), 124.8
(2C), 126.6 (2C), 130.4, 130.5, 134.8, 139.1 (2C), 160.4, 164.0; m/z
(EI) [M+H]+: 394.30 (C24H19N5O requires 393.16).
5.3.19. 10-(4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-yl)butyl)-
10H-phenothiazine (4b)
This compound was obtained by hydrogenation of 10-((1E,3Z)-
4-(2-(4-methoxyphenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-
10H-phenothiazine (2c, 0.43 g, 1 mmol) to give the product as
beige crystals, 0.28 g (65%); mp 82–86 °C; (Found: C, 67.07; H,
5.04; N, 16.32; C24H23N5OS requires C, 67.11; H, 5.40; N, 16.30%);
mmax (KBr)/cmꢂ1: 2945, 1512, 1455, 1254 and 999; 1H NMR
(300 MHz; CDCl3)
d (ppm): 1.87–2.09 (4H, m), 2.99 (2H, t,
J = 6.6 Hz), 3.88 (3H, s), 3.93 (2H, t, J = 6.0 Hz), 6.84–6.92 (4H, m),
7.00–7.04 (2H, m), 7.07–7.18 (4H, m), 7.98 (2H, m); 13C NMR
(75 MHz; CDCl3) d (ppm): 25.1, 25.3, 26.2, 46.8, 55.7, 114.6 (2C),
115.4 (2C), 121.3 (2C), 122.4 (2C), 125.2 (2C), 127.2 (2C), 127.5
(2C), 130.5, 145.2 (2C), 160.4, 166.4; m/z (EI) [M+H]+: 430.20
(C24H23N5OS requires 429.16).
5.3.16. 9-((1E,3Z)-4-(2-(p-Tolyl)-2H-tetrazol-5-yl)buta-1,3-dien-
1-yl)-9H-carbazole (3d)
This compound was obtained from 3-(p-tolyl)-tetrazolo[1,5-
a]pyridin-4-ium tetrafluoroborate (1d, 1.64 g, 5.5 mmol). Recrys-
tallization from dimethyl formamide/MeOH gave yellow crystals,
1.30 g (63%); mp 190–195 °C; (Found: C, 76.28; H, 4.86; N, 18.59;
5.3.20. 10-(4-(2-(p-Tolyl)-2H-tetrazol-5-yl)butyl)-10H-
phenothiazine (4c)
This compound was obtained by hydrogenation of 10-((1E,3Z)-
4-(2-(p-tolyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-phenothi-
azine (2d, 0.20 g, 0.5 mmol) to give the product as beige crystals,
0.04 g (20%); mp 71–75 °C; (Found: C, 69.41; H, 5.74; N, 16.86;
C
24H19N5 requires C, 76.37; H, 5.07; N, 18.55%); mmax (KBr)/cmꢂ1
:
3043, 1638, 1494, 1453 and 1000; 1H NMR (300 MHz; CDCl3) d
(ppm): 2.45 (3H, s), 6.52 (1H, d, J = 11.4 Hz), 6.80 (1H, t,
J = 11.4 Hz), 7.25–7.36 (4H, m), 7.51 (2H, t, J = 8.4 Hz), 7.60 (1H,
d, J = 14.1 Hz), 7.90 (2H, d, J = 8.4 Hz), 8.04–8.10 (4H, m), 8.32
(1H, dd, J = 14.1, 11.4 Hz); 13C NMR (75 MHz; CDCl3) d (ppm):
21.6, 111.5, 111.6 (2C), 114.4, 119.9 (2C), 120.7 (2C), 122.0 (2 C),
125.2 (2C), 127.0 (2C), 130.6 (2 C), 130.9, 135.0, 135.3, 139.6
(2C), 140.2, 164.5; m/z (EI) [M+H]+: 378.30 (C24H19N5 requires
377.16).
C24H23N5S requires C, 69.71; H, 5.61; N, 16.94%); mmax (KBr)/
cmꢂ1: 3394, 2877, 1515, 1455 and 1006; 1H NMR (300 MHz;
CDCl3) d (ppm): 1.93–2.05 (4H, m), 2.43 (3H, s), 3.00 (2H, t,
J = 7.0 Hz), 3.92 (2H, t, J = 6.6 Hz), 6.84–6.91 (4H, m), 7.10–7.15
(4H, m), 7.32 (2H, m), 7.94 (2H, m); 13C NMR (75 MHz; CDCl3) d
(ppm): 21.3, 25.2, 25.5, 26.4, 47.0, 115.6 (2C), 119.8 (2C), 122.6
(2C), 125.4 (2C), 127.3, 127.6 (2C), 130.2 (2C), 131.8, 139.8 (2C),
145.4 (2C), 166.6; m/z (EI) [M+H]+: 414.30 (C24H23N5S requires
413.17).
5.3.17. General procedure for preparation of N-tetrazolylbutyl-
phenothiazines (4a–g)
5.3.21. 10-(4-(2-(4-Fluorophenyl)-2H-tetrazol-5-yl)butyl)-10H-
phenothiazine (4d)
A mixture of the appropriate dienylphenothiazine (2, 1 mmol),
Pd/C Selcat Q-6 (10%, 0.30 g) and abs. triethylamine (0.28 cm3,
2 mmol) in MeOH (10 cm3)/CH2Cl2 (2 cm3) was hydrogenated
(1 atm, under atmospheric pressure) at room temperature until
the absorption of hydrogen ceased (1 day). After the Pd/C catalyst
was filtered off, the solvent was removed in vacuo. The residue
was diluted with water, pH was adjusted to 8 by 10% NaHCO3 solu-
tion. The product was extracted with dichloromethane (thrice).
The combined organic phase was dried over anhydrous Na2SO4, fil-
tered and concentrated. The residue was triturated with diethyl
ether and few drops of hexane, then the resulting crystals were col-
lected by filtration.
This compound was obtained by hydrogenation of 10-((1E,3Z)-
4-(2-(4-fluorophenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-
phenothiazine (2e, 0.41 g, 1 mmol) to give the product as beige
crystals, 0.24 g (57%) which became liquid above room tempera-
ture; (Found: C, 66.16; H, 4.84; N, 16.79; C23H20FN5S requires C,
66.17; H, 4.83; N, 16.77%); mmax (liquid film)/cmꢂ1: 2941, 2863,
1514, 1460 and 1236; 1H NMR (300 MHz; CDCl3) d (ppm): 1.92–
2.03 (4H, m), 3.00 (2H, t, J = 6.9 Hz), 3.93 (2H, t, J = 6.6 Hz), 6.84–
6.92 (4H, m), 7.11–7.26 (6H, m), 8.05 (2H, m); 13C NMR (75 MHz;
CDCl3) d (ppm): 25.2, 25.4, 26.3, 47.0, 115.6 (2C), 116.7 (2C, d,
3
2JC,F = 23 Hz), 121.9 (2C, d, JC,F = 2 Hz), 122.6 (2C), 125.4 (2C),
1
127.3 (2C), 127.7 (2C), 133.5, 145.4 (2C), 163.0 (d, JC,F = 249 Hz),
5.3.18. 10-(4-(2-Phenyl-2H-tetrazol-5-yl)butyl)-10H-
167.0; m/z (EI) [M+H]+: 418.30 (C23H20FN5S requires 417.14).
phenothiazine (4a)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-bromo-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-pheno-thiazine
(2a, 0.47 g, 1 mmol) to give a crystalline product 0.04 g (10%)
which became liquid (brown oil) at room temperature; (Found:
C, 69.01; H, 5.01; N, 17.35; C23H21N5S requires C, 69.15; H, 5.30;
N, 17.53%); mmax (liquid film)/cmꢂ1: 2785, 2770, 1506, 1454 and
760; 1H NMR (300 MHz; CDCl3) d (ppm): 1.95–2.02 (4H, m), 3.02
(2H, t, J = 6.8 Hz), 3.93 (2H, t, J = 6.6 Hz), 6.85–6.92 (4H, m), 7.11–
7.15 (4H, m), 7.44–7.56 (3H, m), 8.08 (2H, m); 13C NMR (75 MHz;
CDCl3) d (ppm): 25.3, 25.5, 26.4, 47.0, 115.7 (2C), 120.0 (2C),
5.3.22. 10-(4-(2-Phenyl-2H-tetrazol-5-yl)butyl)-2-
(trifluoromethyl)-10H-phenothiazine (4e)
This compound was obtained by hydrogenation of 10-((1E,3Z)-
4-(2-(4-bromophenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-2-
(trifluoromethyl)-10H-phenothiazine (2f, 0.54 g, 0.99 mmol) to
give the product as beige crystal, 0.07 g (15%); mp 81–83 °C;
(Found: C, 61.72; H, 4.55; N, 14.68; C24H20F3N5S requires C,
61.66; H, 4.31; N, 14.98%); mmax (KBr)/cmꢂ1: 2938, 2872, 1599,
1467 and 998; 1H NMR (300 MHz; CDCl3) d (ppm): 1.95–2.02
(4H, m), 3.02 (2H, t, J = 6.9 Hz), 3.96 (2H, t, J = 6.6 Hz), 6.86–6.96

4266
D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
(2H, m), 7.02 (1H, s), 7.11–7.21 (4H, m), 7.44–7.56 (3H, m), 8.06
(2H, m); 13C NMR (75 MHz; CDCl3) d (ppm): 25.0, 25.2, 26.0,
47.0, 111.8, 115.8, 119.1, 119.7 (2C), 123.1, 124.4, 124.5 (q,
1JC,F = 270 Hz), 127.5 (2C), 127.6, 129.4, 129.6, 130.2, 131.0 (q,
2JC,F = 32 Hz), 134.4, 136.8, 144.3, 145.7, 166.5; m/z (EI) [M+H]+:
468.40 (C24H20F3N5S requires 467.14).
The same product (5a, 0.15 g, 80%) was obtained by hydrogena-
tion of 9-((1E,3Z)-4-(2-(4-chlorophenyl)-2H-tetrazol-5-yl)buta-
1,3-dien-1-yl)-9H-carbazole (3b).
5.3.27. 9-(4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-yl)butyl)-9H-
carbazole (5b)
This compound was obtained by hydrogenation of 9-((1E,3Z)-4-
(2-(4-methoxyphenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-9H-
carbazole (3c, 0.39 g, 1 mmol) to give the product, 0.23 g (57%); mp
100–103 °C; (Found: C, 72.36; H, 5.85; N, 17.77; C24H23N5O re-
quires C, 72.52; H, 5.83; N, 17.62%); mmax (KBr)/cmꢂ1: 2956, 1514,
1463, 1256 and 752; 1H NMR (300 MHz; CDCl3) d (ppm): 1.90–
2.05 (4H, m), 2.99 (2H, t, J = 7.2 Hz), 3.87 (3H, s), 4.37 (2H, t,
J = 6.6 Hz), 7.00 (2H, m), 7.19–7.25 (2H, m), 7.40–7.47 (4H, m),
7.96 (2H, m), 8.08–8.10 (2H, m); 13C NMR (75 MHz; CDCl3) d
(ppm): 25.3, 25.9, 28.5, 42.9, 55.9, 108.8 (2C), 114.8 (2C), 119.0
(2C), 120.4 (2C), 121.3 (2C), 122.9 (2C), 125.6 (2C), 130.7, 140.4,
160.4, 166.2; m/z (EI) [M+H]+: 398.20 (C24H23N5O requires 397.19).
5.3.23. 10-(4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-yl)butyl)-2-
(trifluoromethyl)-10H-phenothiazine (4f)
This compound was obtained by hydrogenatiom of 10-((1E,3Z)-
4-(2-(4-methoxyphenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-2-
(trifluoromethyl)-10H-phenothiazine (2g, 0.49 g, 1.0 mmol) to give
the product as brown crystals, 0.49 g (99%) which became liquid at
room temperature; (Found: C, 59.99; H, 4.16; N, 13.98;
C
25H22F3N5OS requires C, 60.35; H, 4.46; N, 14.08%); mmax (liquid
film)/cmꢂ1 3064, 2940, 1598, 1423 and 1000; 1H NMR
(300 MHz; CDCl3) (ppm): 1.91–2.04 (4H, m), 2.99 (2H, t,
:
d
J = 5.7 Hz), 3.88 (3H, s), 3.95 (2H, t, J = 6.6 Hz), 6.86–6.97 (2H, m),
7.00–7.03 (3H, m), 7.10–7.20 (4H, m), 7.96 (2H, m); 13C NMR
(75 MHz; CDCl3) d (ppm): 24.9, 25.1, 25.9, 47.0, 55.6, 111.7,
114.5 (2C), 115.8, 119.1, 121.2 (2C), 123.1, 124.2, 124.5 (q,
1JC,F = 270 Hz), 127.4, 127.5 (2C), 130.1, 130.3, 131.0 (q,
2JC,F = 32 Hz), 144.2, 145.6, 160.3, 166.2; m/z (EI) [M+H]+: 498.40
(C25H22F3N5OS requires 497.15).
5.3.28. 9-(4-(2-(p-Tolyl)-2H-tetrazol-5-yl)butyl)-9H-carbazole
(5c)
This compound was obtained by hydrogenation of 9-((1E,3Z)-4-
(2-(p-tolyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-9H-carbazole
(3d, 0.38 g, 1 mmol) to give the product, 0.20 g (52%); mp 89–
93 °C; (Found: C, 75.36; H, 6.03; N, 18.57; C24H23N5 requires C,
75.56; H, 6.08; N, 18.36%); mmax (KBr)/cmꢂ1: 2929, 1515, 1469,
1232 and 818; 1H NMR (300 MHz; CDCl3) d (ppm): 1.95–2.05
(4H, m), 2.44 (3H, s), 3.02 (2H, t, J = 7.1 Hz), 4.38 (2H, t,
J = 6.6 Hz), 7.21–7.49 (8H, m), 7.94 (2H, m), 8.09–8.12 (2H, m);
13C NMR (75 MHz; CDCl3) d (ppm): 21.4, 25.3, 25.9, 28.5, 42.9,
108.8 (2C), 119.1 (2C), 119.9 (2C), 120.6 (2C), 123.1 (2C), 125.9
(2C), 130.3 (2C), 134.9, 140.0, 140.6 (2C), 166.5; m/z (EI) [M+H]+:
382.30 (C24H23N5 requires 381.20).
5.3.24. 10-(4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-yl)butyl)-2-
(2-methyl-1,3-dioxolan-2-yl)-10H-phenothiazine (4g)
This compound was obtained by hydrogenation of 10-((1E,3Z)-
4-(2-(4-methoxyphenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-2-
(2-methyl-1,3-dioxolan-2-yl)-10H-phenothiazine
(2h,
0.4 g,
0.78 mmol) to give the product as beige crystals, 0.21 g (53%);
mp 93–94 °C; (Found: C, 65.39; H, 5.79; N, 13.31; C28H29N5O3S re-
quires C, 65.22; H, 5.67; N, 13.58%); mmax (KBr)/cmꢂ1: 2953, 1513,
1254, 1038 and 832; 1H NMR (300 MHz; CDCl3) d (ppm): 1.61
(3H, s), 1.93–2.06 (4H, m), 2.99 (2H, t, J = 6.8 Hz), 3.73 (2H, t,
J = 7.0 Hz), 3.88 (3H, s), 3.93–4.03 (4H, m), 6.86–7.15 (9H, m),
7.97 (2H, m); 13C NMR (75 MHz; CDCl3) d (ppm): 25.3, 25.6, 26.5,
27.8, 47.0, 55.9, 64.6 (2C), 108.9, 112.8, 114.8 (2C), 115.8, 119.7,
121.5 (2C), 122.7, 125.1, 125.4, 127.4 (2C), 127.8, 130.7, 143.0,
145.4 (2C), 160.6, 166.6; m/z (EI) [M+H]+: 516.50 (C28H29N5O3S re-
quires 515.20).
5.3.29. General procedure for preparation of azaborinines (7i–j)
In an inert atmosphere at 0 °C, BH3 ꢀ Me2S (1.2 cm3, 12 mmol)
was added to the suspension of the appropriate dienylphenothi-
azine (3 mmol) and abs. THF (30 cm3). After injection of
BH3 ꢀ Me2S, the mixture was stirred from 0 °C to room tempera-
ture for 1 day. During this time, the starting suspension turned to
be a clear solution. This mixture was cooled to 0 °C and the excess
of BH3 ꢀ Me2S was quenched with cold water (30 cm3). Then the
reaction mixture was made alkaline with Na2CO3 (10% aqueous,)
and extracted with 3 ꢀ 25 cm3 dichloromethane. The organic
phase was dried over anhydrous Na2SO4, filtered and evaporated
under reduced pressure at room temperature. The residue was
purified with flash chromatography on silica gel (gradient from
hexane:CH2Cl2 = 2:1). The solid product was recrystallized from
hexane and diethyl ether. The crystals were collected by filtration.
5.3.25. General procedure for preparation of tetrazolylbutyl-
carbazoles (5a–c)
A suspension of the appropriate dienylcarbazole (3, 1 mmol),
Pd/C Selcat Q-6 (10%, 0.30 g) and abs. triethylamine (0.14 cm3,
1 mmol) in a mixture of MeOH (10 cm3) and CH2Cl2 (2 cm3) was
hydrogenated (1 atm, under atmospheric pressure) at room tem-
perature until the absorption of hydrogen ceased (1 day). After
the catalyst was filtered off, washed with dichloromethane, the
solvent was dried over anhydrous Na2SO4 and evaporated. The res-
idue was dissolved in hot ethanol and a few drops of water was
added, whereupon colorless crystals were separated.
5.3.30. 2-(4-Bromophenyl)-6-((2-chloro-10H-phenothiazin-10-
yl)methyl)-5,6,7,8-tetrahydro-2H-tetrazolo[5,1-
f][1,2]azaborinin-4-ium-5-uide (7i)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-bromo-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-2-chloro-10H-phe-
nothiazine (2i, 1.53 g, 3 mmol) to give yellow crystals, 0.27 g (18%);
mp 149–151 °C; (Found: C, 52.27; H, 3.89; N, 12.99;
5.3.26. 9-(4-(2-Phenyl-2H-tetrazol-5-yl)butyl)-9H-carbazole (5a)
This compound was prepared from 9-((1E,3Z)-4-(2-(4-bromo-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-9H-carbazole
(3a,
0.22 g, 0.5 mmol), to give 0.18 g (98%) of product; mp 94–95 °C;
(Found: C, 74.83; H, 5.58; N, 19.29; C23H21N5 requires C, 75.18;
H, 5.76; N, 19.06%); mmax (KBr)/cmꢂ1: 2942, 1597, 1484, 1233 and
747; 1H NMR (300 MHz; CDCl3) d (ppm): 1.95–2.02 (4H, m), 3.01
(2H, t, J = 7.1 Hz), 4.37 (2H, t, J = 6.4 Hz), 7.19–7.22 (2H, m), 7.39–
7.55 (7H, m), 8.03–8.10 (4H, m); 13C NMR (75 MHz; CDCl3) d
(ppm): 25.3, 25.9, 28.5, 42.9, 108.8 (2C), 119.1 (2C), 120.0 (2C),
120.6 (2C), 123.1 (2C), 125.9 (2C), 129.7, 129.8 (2C), 137.1, 140.6
(2C), 166.6; m/z (EI) [M+H]+: 368.20 (C23H21N5 requires 367.18).
C23H20BBrClN5S requires C, 52.65; H, 3.84; N, 13.35%); mmax (KBr)/
cmꢂ1: 3432, 2922, 2369, 1453 and 1109; 1H NMR (300 MHz;
CDCl3) d (ppm): 1.64–1.70 (2H, m), 2.29–3.12 (5H, m), 3.64–4.06
(2H, m), 6.85–7.51 (7H, m), 7.75 (2H, m), 8.00 (2H, m); 13C NMR
(75 MHz; CDCl3) d (ppm): 21.8, 22.5, 25.2, 52.1, 116.7, 116.9,
121.8 (2C), 122.1, 122.7, 124.0, 125.3, 126.2, 127.5, 127.6, 128.0,
133.4, 133.6 (2C), 134.8, 145.7, 147.8, 162.5; m/z (EI) [M+Na]+:
546.40 (C23H20BBrClN5S requires 524.67).

D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
4267
5.3.31. 6-((2-Chloro-10H-phenothiazin-10-yl)methyl)-2-(4-
methoxyphenyl)-5,6,7,8-tetrahydro-2H-tetrazolo[5,1-
f][1,2]azaborinin-4-ium-5-uide (7j)
This compound was obtained from 2-chloro-10-((1E,3Z)-4-(2-
(4-methoxyphenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-
phenothiazine (2j, 1.38 g, 3 mmol) to give white crystals, 0.63 g
(46%); mp 153–157 °C; (Found: C, 60.20; H, 4.93; N, 14.81;
(2b, 0.86 g, 2.0 mmol) to give white crystals, 0.66 g (73%); mp 95–
100 °C; (Found: C, 61.16; H, 4.17; N, 15.53; C23H20ClN5OS requires
C, 61.39; H, 4.48; N, 15.56%); mmax (KBr)/cmꢂ1: 3230, 2890, 1456,
1097 and 755; 1H NMR (300 MHz; CDCl3) d (ppm): 2.05 (1H, m),
2.13 (1H, br s), 2.21 (1H, m), 3.19 (2H, m), 3.94 (1H, m), 4.06
(1H, m), 4.17 (1H, m), 6.92–6.98 (4H, m), 7.13–7.21 (4H, m), 7.52
(2H, m), 8.03 (2H, m); 13C NMR (75 MHz; CDCl3) d (ppm): 21.9,
32.1, 53.8, 66.4, 116.1 (2C), 120.9 (2C), 123.2 (2C), 126.7 (2C),
127.4 (2C), 127.8 (2C), 129.8 (2C), 135.3, 135.4, 145.3 (2C), 166.8;
m/z (EI) [M+H]+: 450.30 (C23H20ClN5OS requires 449.11).
C
24H23BClN5OS requires C, 60.58; H, 4.87; N, 14.72%); mmax (KBr)/
cmꢂ1: 3337, 2920, 2339, 1454 and 1109; 1H NMR (400 MHz;
CDCl3) d (ppm): 1.64 (1H, m, H7y), 1.71 (1H, m, H6), 2.27 (1H, m,
H7x), 2.40 (1H, br s, H5y), 2.75 (1H, br s, H5x), 2.79 (1H, ddd,
J = 17.7, 10.0, 5.6 Hz, H8y) 3.05 (1H, ddd, J = 17.7, 5.0, 4.9 Hz,
H8x), 3.67 (1H, dd, J = 14.2, 11.1 Hz, Hy), 4.07 (1H, dd, J = 14.2,
3.1 Hz, Hx), 6.84 (1H, dd, J = 8.2, 2.0 Hz, H300), 6.90 (1H, td, J = 7.4,
1.8 Hz, H700), 6.93 (1H, d, J = 2.0 Hz, H100), 6.97 (1H, dd, J = 7.4,
1.8 Hz, H900), 7.01 (1H, d, J = 8.2 Hz, H400), 7.04 (2H, m, H30 + H50),
7.12 (1H, dd, J = 7.4, 1.5 Hz, H600), 7.14 (1H, td, J = 7.4, 1.5 Hz,
H800), 8.01 (2H, m, H20 + H60); 13C NMR (100 MHz; CDCl3) d
(ppm): 21.6 (C6), 22.1 (C8), 25.1 (C7), 51.9 (C), 55.8 (OCH3),
115.0 (C30 + C50), 116.5 (C100), 116.7 (C900), 121.7 (C300), 121.8
(C20 + C60), 122.4 (C700), 123.8 (C4a00), 125.0 (C5a00), 127.3 (C800),
127.4 (C600), 127.8 (C400), 129.0 (C10), 133.2 (C200), 145.6 (C9a00),
147.6 (C10a’’), 161.6 (C40), 161.9 (C8a); m/z (EI) [M+Na]+: 498.50
(C24H23BClN5OS requires 475.14).
5.3.35. 4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-yl)-1-(10H-
phenothiazin-10-yl)butan-2-ol (8c)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-
methoxyphenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-phe-
nothiazine (2c, 1.28 g, 3 mmol). White crystals, 0.89 g (67%); mp
104–107 °C; (Found: C, 64.69; H, 5.23; N, 15.60; C24H23N5O2S re-
quires C, 64.70; H, 5.20; N, 15.72%); mmax (KBr)/cmꢂ1: 3382, 1516,
1460, 1266 and 746; 1H NMR (300 MHz; CDCl3) d (ppm): 2.06
(1H, m), 2.20 (1H, m), 2.53 (1H, br s), 3.15 (2H, m), 3.84–4.19
(6H, m), 6.91–7.04 (6H, m), 7.12–7.21 (4H, m), 7.98 (2H, m,); 13C
NMR (75 MHz; CDCl3) d (ppm): 22.2, 32.5, 53.8, 56.0, 66.8, 114.9
(2C), 116.4 (2 C), 121.6 (2C), 123.4 (2C), 127.0 (2C), 127.7 (2C),
128.1 (2C), 130.7, 145.6 (2C), 160.7, 166.7; m/z (EI) [M+H]+:
446.30 (C24H23N5O2S requires 445.16).
5.3.32. General procedure for preparation of tetrazolylbutan-2-
olphenothiazines (8a–i)
5.3.36. 1-(10H-Phenothiazin-10-yl)-4-(2-(p-tolyl)-2H-tetrazol-5-
yl)-butan-2-ol (8d)
To
a solution of the appropriate dienylphenothiazine (2,
4 mmol) in abs. THF (40 cm3) in a dried, round-bottomed flask
equipped with a side arm and cooled to 0 °C in an argon atmo-
sphere was added BH3 ꢀ Me2S (1.6 cm3, 16 mmol) dropwise by
injection. After addition, the resulting yellow suspension was al-
lowed to warm up to room temperature and maintained at this
temperature for prologued time. After the completion of the rea-
tion (1 day, monitored by TLC), the reaction mixture was cooled
to 0 °C with an ice bath, and treated with methanol (30 cm3),
10% aqueous NaOH (2 cm3) and H2O2 (30% aqueous solution,
2 cm3). This mixture was then stirred at room temperature for 1
more day. The solution was then poured onto ice cold water, acid-
ified with 10% aqueous HCl and extracted with dichloromethane
(3 ꢀ 30 cm3). The combined organic phase was dried over anhy-
drous Na2SO4, filtered and concentrated. The residue was purified
by column chromatography on silica gel using the eluent CH2Cl2
then hexane:EtOAc = 2:1. The crude product (foam) was triturated
with diethyl ether, the mixture was cooled whereupon crystals
deposited. The product was collected by filtration.
This compound was obtained from 10-((1E,3Z)-4-(2-(p-tolyl)-
2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-phenothiazine
(2d,
0.60 g, 1.47 mmol). White crystals, 0.34 g (54%); mp 110–115 °C;
(Found: C, 67.00; H, 5.34; N, 16.48; C24H23N5OS requires C,
67.11; H, 5.40; N, 16.30%); mmax (KBr)/cmꢂ1: 3394, 1514, 1455,
1097 and 747; 1H NMR (300 MHz; CDCl3) d (ppm): 1.75 (1H, br
s), 2.06 (1H, m), 2.23 (1H, m), 2.44 (3H, s), 3.16 (2H, m), 3.92
(1H, m), 4.06 (1H, m), 4.18 (1H, m), 6.90–6.99 (4H, m), 7.13–7.21
(4H, m), 7.32–7.34 (2H, m), 7.95 (2H, m); 13C NMR (75 MHz; CDCl3)
d (ppm): 21.2, 21.9, 32.2, 53.7, 66.5, 116.1 (2C), 119.7 (2C), 123.2
(2C), 126.8 (2C), 127.4 (2C), 127.8 (2C), 130.1 (2C), 134.7, 139.8,
145.3 (2C), 166.4; m/z (EI) [M+H]+: 430.20 (C24H23N5OS requires
429.16).
5.3.37. 4-(2-(4-Fluorophenyl)-2H-tetrazol-5-yl)-1-(10H-
phenothiazin-10-yl)butan-2-ol (8e)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-fluoro-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-phenothiazine
(2e, 0.6 g, 1.45 mmol). Brown crystals, 0.49 g (78%); mp 59–61 °C;
(Found: C, 63.51; H, 4.61; N, 15.95; C23H20FN5OS requires C, 63.72;
H, 4.65; N, 16.16%); mmax (KBr)/cmꢂ1: 3250, 1514, 1454, 1219 and
749; 1H NMR (300 MHz; CDCl3) d (ppm): 1.74 (1H, br s), 2.06
(1H, m), 2.21 (1H, m), 3.16 (2H, m), 3.78–4.24 (3H, m), 6.80–7.07
(3H, m), 7.08–7.26 (7H, m), 8.07 (2H, m); 13C NMR (75 MHz; CDCl3)
5.3.33. 4-(2-(4-Bromophenyl)-2H-tetrazol-5-yl)-1-(10H-
phenothiazin-10-yl)butan-2-ol (8a)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-bromo-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-phenothiazine
(2a, 1.90 g, 4.0 mmol) to give white crystals, 1.7 g (84%); mp 103–
105 °C; (Found: C, 55.93; H, 3.75; N, 13.99; C23H20BrN5OS requires
C, 55.87; H, 4.08; N, 14.17%); mmax (KBr)/cmꢂ1: 3399, 1457, 1001,
825 and 754; 1H NMR (300 MHz; CDCl3) d (ppm): 1.64 (1H, br s),
2.06 (1H, m), 2.23 (1H, m), 3.18 (2H, m), 3.94 (1H, m), 4.06 (1H,
m), 4.17 (1H, m), 6.92–6.98 (4H, m), 7.13–7.26 (4H, m), 7.67–
7.70 (2H, m), 7.97 (2H, m); 13C NMR (75 MHz; CDCl3) d (ppm):
21.9, 32.1, 53.8, 66.4, 116.1 (2C), 121.2 (2C), 123.2 (2C), 126.8
(2C), 127.4 (2C), 127.8 (2C), 132.3, 132.8 (2C), 135.8, 145.3 (2C),
166.9; m/z (EI) [M+H]+: 494.20 (C23H20BrN5OS requires 493.06).
d
(ppm): 21.9, 32.1, 53.8, 66.4, 116.1 (2C), 116.6 (2C, d,
3
2JC,F = 23 Hz), 121.7 (2C, d, JC,F = 8 Hz), 123.2 (2C), 126.8 (2C),
1
127.4 (2C), 127.8 (2C), 145.3 (2C), 162.9 (d, JC,F = 249 Hz), 166.8;
m/z (EI) [M+H]+: 434.40 (C23H20FN5OS requires 433.14).
5.3.38. 4-(2-(4-Bromophenyl)-2H-tetrazol-5-yl)-1-(2-
(trifluoromethyl)-10H-phenothiazin-10-yl)butan-2-ol (8f)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-bromo-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-2-(trifluoromethyl)-
10H-phenothiazine (2f, 0.54 g, 1 mmol). White crystals, 0.23 g
(41%); mp 139–141 °C; (Found: C, 51.07; H, 3.37; N, 12.25;
5.3.34. 4-(2-(4-Chlorophenyl)-2H-tetrazol-5-yl)-1-(10H-
phenothiazin-10-yl)butan-2-ol (8b)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-chloro-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-10H-phenothiazine
C
24H19BrF3N5OS requires C, 51.25; H, 3.41; N, 12.45%); mmax
(KBr)/cmꢂ1 3364, 2937, 1501, 1331 and 1119; 1H NMR
(300 MHz; CDCl3) d (ppm): 2.07 (1H, m), 2.23 (2H, m), 2.66 (1H,
:

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D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
s), 3.18 (2H, m), 3.96 (1H, m), 4.06–4.16 (2H, m), 6.93–7.28 (7H, m),
7.65–7.68 (2H, m), 7.95 (2H, m); 13C NMR (75 MHz; CDCl3) d
(ppm): 21.8, 32.0, 54.0, 66.3, 112.9, 116.7, 120.0, 121.4 (2C),
zol-5-yl)butan-2-ol (8i, 1.25 g, 65%) as white crystal was collected
by filtration; mp 100–102 °C; (Found: C, 60.05; H, 4.62; N, 14.51;
C24H22ClN5O2S requires C, 60.06; H, 4.62; N, 14.59%); mmax (KBr)/
1
123.6, 124.1, 124.5 (q, JC,F = 270 Hz), 125.9, 128.0, 128.1, 128.2,
cmꢂ1: 3393, 2963, 1518, 1456 and 1254; 1H NMR (600 MHz;
DMSO) d (ppm): 1.80 (1H, dddd, J = 13.6, 9.3, 8.1, 5.1 Hz, H3y),
2.13 (1H, dddd, J = 13.6, 9.1, 8.2, 2.6 Hz, H3x), 2.96 (1H, ddd,
J = 15.2, 8.2, 8.1 Hz, H4y), 3.06 (1H, ddd, J = 15.2, 9.1, 5.1 Hz,
H4x), 3.84 (3H, s, OCH3), 3.85 (1H, m, H1y), 3.94 (1H, m, H2),
3.95 (1H, m, H1x), 5.07 (1H, br s, OH), 6.94 (1H, m, H300), 6.95
(1H, m, H700), 7.07 (1H, m, H900), 7.10 (1H, m, H400), 7.11 (1H,
H800), 7.13 (1H, m, H100), 7.15 (2H, m, H30 + H50), 7.18 (1H, m,
H600), 7.87 (2H, m, H20 + H60); 13C NMR (150 MHz; DMSO) d
(ppm): 21.0 (C4), 32.9 (C3), 53.0 (C1), 55.6 (OCH3), 65.3 (C2),
114.9 (C30 + C50), 116.1 (C100), 116.5 (C900), 121.2 (C20 + C60), 122.2
(C700), 123.0 (C5a00), 123.8 (C4a00), 127.2 (C800), 127.7 (C600), 128.1
(C400), 129.6 (C10), 132.4 (C200), 144.4 (C9a00), 146.5 (C10a00), 160.1
2
130.1 (q, JC,F = 32 Hz), 131.6, 133.0 (2C), 135.9, 144.5, 146.2,
166.9; m/z (EI) [M+H]+: 562.30 (C24H19BrF3N5OS requires 561.04).
5.3.39. 4-(2-(4-Methoxyphenyl)-2H-tetrazol-5-yl)-1-(2-
(trifluoromethyl)-10H-phenothiazin-10-yl)butan-2-ol (8g)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-meth-
oxy-phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-2-(trifluoro-
methyl)-10H-phenothiazine (2g, 0.50 g, 1 mmol). White crystals,
0.084 g (16%); mp 126–128 °C; (Found: C, 58.27; H, 4.38; N,
13.63; C25H22F3N5O2S requires C, 58.47; H, 4.32; N, 13.64%); mmax
:
(KBr)/cmꢂ1 3366, 2938, 1517, 1333 and 1120; 1H NMR
(300 MHz; CDCl3) d (ppm): 2.07 (1H, m), 2.23 (1H, m), 2.70 (1H,
br s), 3.16 (2H, m), 3.88 (3H, s), 3.97 (1H, m), 4.06–4.17 (2H, m),
6.94–7.04 (4H, m), 7.11 (1H, s), 7.14–7.20 (3H, m), 7.25 (1H, d,
J = 7.8 Hz), 7.97 (2H, m); 13C NMR (75 MHz; CDCl3) d (ppm): 22.0,
32.4, 54.2, 55.9, 66.7, 112.9, 114.8 (2C), 116.7, 120.0, 121.5 (2C),
(C40), 166.4 (Ctetrazole); 15N NMR (60 MHz; DMSO)
d (ppm):
ꢂ285.2 (N1000), ꢂ92.0 (N2tetrazole), ꢂ87.1 (N1tetrazole), and ꢂ47.9
(N4tetrazole); m/z (EI) [M+H]+: 480.30 (C24H22ClN5O2S requires
479.12).
1
124.0, 124.5 (q, JC,F = 270 Hz), 125.8, 128.0, 128.1, 128.2, 130.1
Column chromatography of the mother liquor resulted in sepa-
ration of two more products. Thus, first the fractions of the less po-
lar component were collected, evaporated and the obtained solid
was recrystallized from dichloromethane to yield 4-(2-chloro-
10H-phenothiazin-10-yl)-1-(2-(4-methoxyphenyl)-2H-tetrazol-5-yl)-
butane-1,3-diol (10, 0.10 g, 6%) as white crystals were collected by
filtration; mp 152–156 °C; (Found: C, 58.13; H, 4.23; N, 13.75;
2
(q, JC,F = 32 Hz), 133.5, 131.6, 144.5, 146.2, 160.6, 166.5; m/z (EI)
[M+H]+: 514.40 (C25H22F3N5O2S requires 513.14).
5.3.40. 4-(2-(4-Bromophenyl)-2H-tetrazol-5-yl)-1-(2-chloro-
10H-phenothiazin-10-yl)butan-2-ol (8h)
This compound was obtained from 10-((1E,3Z)-4-(2-(4-bromo-
phenyl)-2H-tetrazol-5-yl)buta-1,3-dien-1-yl)-2-chloro-10H-phe-
nothiazine (2i, 0.51 g, 1 mmol) to give white crystals, 0.21 g (40%);
mp 101–103 °C; (Found: C, 52.14; H, 3.58; N, 13.28;
C24H22ClN5O3S requires C, 58.12; H, 4.47; N, 14.12%); mmax (KBr)/
cmꢂ1: 3312, 2954, 1516, 1456 and 1257; the obtained diastereo-
meric pair is present in 0.6/0.4 ratio according to NMR spectra
(assignments of the minor component are in italics): 1H NMR
(600 MHz; DMSO) d (ppm): 1.82 (0.4H, ddd, J = 13.8, 9.8, 3.0 Hz,
H3y), 1.98 (0.6H, ddd, J = 12.9, 9.6, 5.4 Hz, H3y), 2.22 (0.4H, ddd,
J= 13.8, 10.3, 2.5 Hz, H3x), 2.37 (0.6H, ddd, J = 12.9, 9.3, 3.0 Hz,
H3y), 3.77 (0.6H, m, H2), 3.85 (3H, s, OCH3), 3.86 (1H, m, H1y),
3.91 (1H, m, H1x), 4.20 (0.4H, m, H2), 5.00 (1H, br s, OH), 5.15
(0.6H, m, H4), 5.16 (0.4H, m, H4), 5.74 (0.4H, br s, OH), 5.81 (0.6H,
br s, OH), 6.90 (0.6, m, H300), 6.91 (0.6H, m, H700), 6.97 (0.4H, m,
H300), 6.98 (0.4H, m, H700), 7.00 (0.6H, m, H900), 7.03 (0.6H, m, H100),
7.06 (0.6H, m, H400), 7.08 (0.6H, m, H800), 7.09 (0.4H, m, H900), 7.11
(0.6H, m, H600), 7.14 (0.4H, m, H400), 7.14 (0.4H, m, H100), 7.16 (0.4H,
m, H800), 7.18 (1.2H, m, H30 + H50), 7.19 (0.8H, m, H30 + H50), 7.21
(0.4H, m, H600), 7.85 (1.2H, m, H20 + H60), 7.96 (0.8H, m,
H20 + H60); 13C NMR (150 MHz; DMSO) d (ppm): 41.3 (C3), 41.4
(C3), 53.0 (C1), 53.4 (C1), 55.7 (OCH3), 61.3 (C4), 62.3 (C4), 62.9
(C2), 63.5 (C2), 115.0 (C30 + C50), 115.1 (C30 + C50), 116.0 (C100),
116.1 (C100), 116.4 (C900), 116.5 (C900), 121.2 (C20 + C60), 121.4
(C20 + C60), 122.0 (C700), 122.1 (C700), 122.9 (C300), 123.0 (C300), 123.1
(C5a00), 123.7 (C4a00), 127.1 (C800), 127.3 (C800), 127.5 (C600), 127.7
(C600), 128.0 (C400), 128.1 (C400), 129.5 (C10), 129.6 (C10), 132.2
(C200), 132.4 (C200), 144.3 (C9a00), 144.5 (C9a00), 146.4 (C10a00), 146.6
(C10a00), 160.2 (C40), 168.5 (Ctetrazole), 169.5 (Ctetrazole); 15N NMR
(60 MHz; DMSO) d (ppm): ꢂ285.3 (N1000), ꢂ92.0 (N2tetrazole),
ꢂ85.3, and ꢂ48.0 (N1tetrazole + N4tetrazole); m/z (EI) [M+Na]+:
518.30 (C24H22ClN5O3S requires 495.11).
C
23H19BrClN5OS requires C; 52.24; H, 3.62; N, 13.24%); mmax
(KBr)/cmꢂ1: 3341, 2926, 1567, 1456 and 999; 1H NMR (300 MHz;
CDCl3) (ppm): 2.08 (1H, m), 2.21 (1H, m), 2.55 (1H, d,
d
J = 1.8 Hz), 3.10–3.28 (2H, m), 3.91 (1H, m), 4.02 (1H, m), 4.17
(1H, m), 6.90–7.00 (4H, m), 7.08–7.20 (3H, m), 7.66–7.69 (2H, m),
7.96–7.99 (2H, m); 13C NMR (75 MHz; CDCl3) d (ppm): 21.9, 32.2,
54.0, 66.5, 116.5, 116.7, 121.3 (2C), 123.2, 123.5, 123.8, 125.2,
126.5, 127.7, 128.0, 128.4, 133.0 (2C), 133.6, 135.9, 144.7, 146.8,
166.9; m/z (EI) [M+H]+: 530.30 (C23H19BrClN5OS requires 528.85).
5.3.41. 1-(2-Chloro-10H-phenothiazin-10-yl)-4-(2-(4-
methoxyphenyl)-2H-tetrazol-5-yl)butan-2-ol (8i), 2-chloro-10-
(2-hydroxy-4-(2-(4-methoxyphenyl)-2H-tetrazol-5-yl)butyl)-
10H-phenothiazine 5-oxide (9), and 4-(2-chloro-10H-
phenothiazin-10-yl)-1-(2-(4-methoxyphenyl)-2H-tetrazol-5-
yl)butane-1,3-diol (10)
A dried, round-bottomed flask, equipped with a side arm, was
cooled to 0 °C under a stream of argon. In the flask 2-chloro-10-
((1E,3Z)-4-(2-(4-methoxyphenyl)-2H-tetrazol-5-yl)buta-1,3-dien-
1-yl)-10H-phenothiazine (2j, 1.84 g, 4.0 mmol) was dissolved in
abs. THF (80 cm3) and BH3 ꢀ Me2S (1.6 cm3, 16 mmol) added drop-
wise to the solution using injection. After addition the resulting
yellow suspension was allowed to warm to room temperature.
After the completion of the reaction (1 day, monitored by TLC),
the reaction mixture was cooled to 0 °C with an ice bath, and
quenched with methanol (40 cm3), NaOH (10% aqueous, 4 cm3)
and H2O2 (30% aqueous, 2 cm3) were added. This mixture was al-
lowed to stir at room temperature for 1 day.
Continued chromatography and collection of the more polar
fractions, evaporation, and recrystallization of the crude product
from ethanol gave 2-chloro-10-(2-hydroxy-4-(2-(4-methoxy-phe-
nyl)-2H-tetrazol-5-yl)butyl)-10H-phenothiazine 5-oxide (9, 0.45 g,
25%) as white crystals were collected by filtration; mp 140–
145 °C; (Found: C, 58.10; H, 4.27; N, 13.82; C24H22ClN5O3S requires
C, 58.12; H, 4.47; N, 14.12%); mmax (KBr)/cmꢂ1: 3377, 2941, 1581,
1515 and 1461; the obtained two diastereomers are present in
0.6/0.4 ratio according to NMR spectra (assignments of the minor
component are in italics): 1H NMR (600 MHz; DMSO) d (ppm):
1.87 (1H, m, H3y), 2.08 (1H, m, H3x), 2.99 (1H, m, H4y), 3.09
The solution was then poured onto ice cold water (60 cm3),
acidified with 10% aqueous HCl and extracted with 3 ꢀ 50 cm3
dichloromethane. The combined organic phase was dried over
anhydrous Na2SO4, filtered and concentrated. The residue was
purified by column chromatography on silica gel using the eluent
CH2Cl2 then hexane:EtOAc = 2:1. The crude product (foam) was
triturated with diethyl ether, cooled and the main product 1-(2-
chloro-10H-phenothiazin-10-yl)-4-(2-(4-methoxyphenyl)-2H-tetra-

D. Takács et al. / Bioorg. Med. Chem. 20 (2012) 4258–4270
4269
(1H, m, H4x), 3.83 (3H, s, OCH3), 4.03 (0.6H, m, H2), 4.11 (0.4H, m,
H2), 4.41 (0.6H, d, J = 15.1 Hz, H1y), 4.43 (0.4H, d, J = 15.1 Hz, H1y),
4.50 (0.6H, d, J = 15.1 Hz, H1x), 4.51 (0.4H, d, J = 15.1 Hz, H1x), 4.88
(0.6H, d, J = 4.8 Hz, OH), 5.00 (0.4H, d, J = 4.8 Hz, OH), 7.15 (2H, m,
H30 + H50), 7.30 (1H, m, H300), 7.31 (1H, m, H700), 7.66 (0.6H, m,
H800), 7.68 (0.4H, m, H8’’), 7.74 (0.4H, d, J = 8.3 Hz, H900), 7.84 (0.6H,
d, J = 1.3 Hz, H100), 7.91 (2H, m, H20 + H60), 7.92 (0.6H, d,
J = 8.3 Hz, H900), 7.94 (1H, m, H600), 7.95 (1H, m, H400), 8.09 (0.4 H,
d, J = 1.3 Hz, H100); 13C NMR (150 MHz; DMSO) d (ppm): 21.0 (C4),
31.9 (C3), 53.1 (C1), 55.6 (OCH3), 66.6 (C2), 67.0 (C2), 114.8
(C30 + C50), 117.3 (C100), 117.5 (C900), 118.0 (C100), 118.3 (C900), 121.0
(C20 + C60), 121.6 (C300), 122.0 (C200), 122.3 (C700), 126.1 (C5a00),
129.6 (C10), 130.0 (C600), 131.7 (C400), 132.5 (C800), 132.7 (C800),
137.1 (C4a00), 138.0 (C9a00), 139.9 (C10a00), 160.0 (C40), 166.2
(300 MHz; CDCl3) d (ppm): 3.88 (3H, s), 7.03 (2H, m), 7.27–7.64
(9H, m), 7.89–8.02 (3H, m); 13C NMR (75 MHz; CDCl3) d (ppm):
55.9, 115.0 (2C), 121.7 (2C), 126.5, 127.2 (2C), 127.3 (2C), 127.4
(2C), 128.2 (2C), 128.3, 130.3 (2C), 132.9, 138.4 (2C), 161.0,
162.5, 163.4; m/z (EI) [M+H]+: 428.30 (C23H17N5O2S requires
427.11).
5.3.44. 10-(3-(2-(4-Methoxyphenyl)-2H-tetrazol-5-yl)propyl)-
10H-phenothiazine (14)
To the green suspension of (E)-3-(2-(4-methoxyphenyl)-2H-tet-
razol-5-yl)-1-(10H-phenothiazin-10-yl)prop-2-en-1-one
(13,
0.21 g, 0.49 mmol) in abs. THF (5 cm3) was added BH3 ꢀ Me2S
(0.2 cm3, 0.16 g, 2.06 mmol) slowly at 0 °C. The color of reaction
mixture changed to yellow, and gas evolution was observed. The
mixture was allowed to warm to room temperature and strirred
for 2.5 h. After evapration of the mixture, MeOH (10 cm3) was
added to the residue at room temperature, intensive gas evolution
was observed, then this mixture was stirred for 4 days. The crude
product was purified by column chromatography using the eluent
CH2Cl2:hexane = 2:1 to give beige crystals, 0.04 g (20%); mp 112–
114 °C; (Found: C, 66.25; H, 5.12; N, 16.78; C23H21N5OS requires
C, 66.48; H, 5.09; N, 16.85%); mmax (KBr)/cmꢂ1: 3063, 2949, 1513,
1459 and 1251; 1H NMR (300 MHz; CDCl3) d (ppm): 2.30–2.42
(2H, m), 3.11 (2H, t, J = 7.4 Hz), 3.87 (3H, s), 4.04 (2H, t,
J = 6.6 Hz), 6.88–7.19 (9H, m), 7.93 (2H, m); 13C NMR (75 MHz;
CDCl3) d (ppm): 23.2, 25.3, 46.6, 56.0, 114.9 (2C), 115.9 (2C),
121.6 (2C), 122.9 (2C), 125.8 (2C), 127.6 (2C), 127.9 (2C), 130.8,
145.5 (2C), 160.7, 166.4; m/z (EI) [M+H]+: 416.20 (C23H21N5OS re-
quires 415.15).
(Ctetrazole); 15N NMR (60 MHz; DMSO)
d
(ppm): ꢂ277.5
(N1000), ꢂ276.5 (N1000), ꢂ92.0 (N2tetrazole), ꢂ86.0, and ꢂ47.8
(N1tetrazole + N4tetrazole); m/z (EI) [M+H]+: 496.30 (C24H22ClN5O3S
requires 495.11).
5.3.42. 1-(9H-Carbazol-9-yl)-4-(2-(4-methoxyphenyl)-2H-
tetrazol-5-yl)butan-2-ol (11)
To a solution of 9-((1E,3Z)-4-(2-(4-methoxyphenyl)-2H-tetra-
zol-5-yl)buta-1,3-dien-1-yl)-9H-carbazole (3c, 0.38 g, 0.96 mmol)
in abs. dichloromethane (25 cm3) in a dried, round-bottomed flask
equipped with a side arm cooled to 0 °C in an argon atmosphere
was added BH3 ꢀ Me2S (0.4 cm3, 4 mmol) dropwise by using injec-
tion. After addition, the resulting yellow suspension was allowed
to warm up to room temperature and maintained at this tempera-
ture. After the completion of the reation (1 day, monitored by TLC),
the reaction mixture was cooled to 0 °C with an ice bath, and trea-
ted with methanol (25 cm3), 10% aqueous NaOH solution (2 cm3)
and 30% aqueous H2O2 (3 cm3). This mixture was then stirred at
room temperature for 1 more day. The solution was then poured
onto ice cold water, acidified with 10% aqueous HCl and extracted
with dichloromethane (3 ꢀ 20 cm3). The combined organic phase
was dried over anhydrous Na2SO4, filtered and concentrated. The
residue was purified by column chromatography on silica gel using
the eluent CH2Cl2 then hexane:EtOAc = 2:1. The crude product
(foam) was triturated with diethyl ether, cooled and the product
was collected by filtration as white crystals, 0.14 g (33%); mp
137–142 °C; (Found: C, 69.33; H, 5.59; N, 16.77; C24H23N5O2 re-
quires C, 69.72; H, 5.61; N, 16.94%); mmax (KBr)/cmꢂ1: 3326, 2931,
1514, 1257 and 755; 1H NMR (300 MHz; CDCl3) d (ppm): 2.16
(2H, m), 2.36 (1H, d, J = 3.6 Hz), 3.18 (2H, m), 3.87 (3H, s), 4.31–
4.39 (3H, m), 7.02 (2H, m), 7.20–7.25 (2H, m), 7.41–7.49 (4H, m),
7.95 (2H, m), 8.08 (2H, m); 13C NMR (75 MHz; CDCl3) d (ppm):
21.8, 32.5, 49.7, 55.6, 70.0, 109.0 (2C), 114.6 (2C), 119.2 (2C),
120.3 (2C), 121.3 (2C), 123.0 (2C), 125.8 (2C), 130.6, 140.8 (2C),
160.4, 166.3; m/z (EI) [M+H]+: 414.20 (C24H23N5O2 requires
413.19).
Acknowledgments
Financial support from the Hungarian Scientific Research Fund
OTKA-NK 77784 and Szeged Foundation for Cancer Research is
gratefully acknowledged. A diffractometer purchase grant from
the National Office for Research and Technology (MU-00338/
2003) is gratefully acknowledged. The results have been achieved
in the frame of the COST action BM0701 ‘‘ATENS’’.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmc.2012.05.065.
References and notes
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5.3.43. (E)-3-(2-(4-Methoxyphenyl)-2H-tetrazol-5-yl)-1-(10H-
phenothiazin-10-yl)prop-2-en-1-one (13)
To the solution of (E)-3-(2-(4-methoxyphenyl)-2H-tetrazol-5-
yl)acrylaldehyde (12, 0.50 g, 2.17 mmol), N-bromo-succimide
(0.42 g, 2.39 mmol) and CCl4 (10 cm3) was added phenotiazine
(0.91 g, 4.56 mmol) dissolved in toluene (10 cm3) and the mixture
was stirring at 110 °C for 3 h. After evaporation of the reaction mix-
ture, the residue was dissolved in dichloromethane (15 cm3). The
organic phase was extracted with water (twice), the organic phase
was dried over anhydrous Na2SO4, filtered and evaporated. The res-
idue was washed with diethyl ether (thrice). It was recrystallized
from acetonitrile and the product (0.32 g, 34%) was filtered off as
yellow crystal; mp 199–204 °C; (Found: C, 64.69; H, 3.96; N,
16.09; C23H17N5O2S requires C, 64.62; H, 4.01; N, 16.38%); mmax
12. Craig, P.; Nodiff, E.; Lafferty, E. J.; Ullyot, G. J. Org. Chem. 1957, 22, 709.
13. Bourquin, J.-P.; Schwarb, G.; Gamboni, G.; Fischer, R.; Ruesch, L.; Guldimann, S.;
Theus, V.; Schenker, E. Helv. Chim. Acta 1958, 41, 1072.
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