Discovery of Tro?ger's base analogues as selective inhibitors against human breast cancer cell line: Design, synthesis and cytotoxic evaluation

Article abstract of DOI:10.1016/j.ejmech.2014.08.044

A library of structurally diverse Tr?ger's base analogues has been constructed via unusual amination of methylene bridge employing Vilsmeier-Haack conditions as well as by the incorporation of five and six membered heterocycles on the aromatic core of Tr?

Full text of DOI:10.1016/j.ejmech.2014.08.044

European Journal of Medicinal Chemistry 86 (2014) 39e47
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
€
Discovery of Troger's base analogues as selective inhibitors against
human breast cancer cell line: Design, synthesis and cytotoxic
evaluation
,
, *
Bhaskar Reddy Manda a, Manjula Alla a *, Roopa Jones Ganji b, Anthony Addlagatta b
a Crop Protection Chemicals Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 607, India
b Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 607, India
a r t i c l e i n f o
a b s t r a c t
Article history:
€
A library of structurally diverse Troger's base analogues has been constructed via unusual amination of
methylene bridge employing VilsmeiereHaack conditions as well as by the incorporation of five and six
Received 3 February 2014
Received in revised form
11 August 2014
Accepted 12 August 2014
Available online 13 August 2014
€
membered heterocycles on the aromatic core of Troger's base framework. The constructed structurally
diverse frameworks were evaluated for their cytotoxic activities against a panel of three human cancer
lines A549 (lung adenocarcinoma), MDAMB-231 (breast) and SK-N-SH (neuroblastoma). From the ac-
tivity profile obtained, a redesign of Troger's base analogues led to the construction of more potent
€
molecular entities. The study led to development of a series of compounds with MDAMB-231 cell line
specific cytotoxicity. Of the 30 compounds synthesized and evaluated, 7 compounds were found to
possess cytotoxicity that is equivalent or better than standard drug doxorubicin against MDAMB-231 cell
line while only one compound was found to be active against SK-N-SH cell line.
© 2014 Elsevier Masson SAS. All rights reserved.
Keywords:
€
Troger's base
VilsmeiereHaack reaction
Amination
Cytotoxicity
1. Introduction
receptors [5], in development of molecular torsion balances [6], in
asymmetric catalysis [7], and as chiral solvating agent [8].
€
€
Troger's base, 2,8-dimethyl-6H,12H-5,11-methanodibenzo[b,f]
Troger's base structural features were utilized in the design and
€
€
[1,8]diazocine (Fig. 1), was first synthesized in 1887 by Julius Troger
development of DNA minor grove binders (Fig. 2). Troger's bases
by the reaction of p-toluidine with methylal [CH2-(OCH3)2] in acidic
conditions [1]. Its correct structure was determined by Spielman in
1935 and assigned as racemic [2]. Later a number of aromatic,
derived from heterocyclic aromatic amines like acridine [9], phe-
nanthroline and proflavine [10] have shown good affinity for DNA.
€
Among these, the geometry of acridine derived Troger's base gives
€
heterocyclic Troger's bases with various functional groups were
rise to a helix shape which can be similar or opposite to the helicity
of DNA, resulting in enantioselective binding to calf-thymus B-DNA
synthesized by using different methylene donors such as para-
formaldehyde, hexamethylenetetramine (HMTA), dimethoxy-
methane, or DMSO and by varying acidic media such as
trifluoroacetic acid (TFA), HCl, or acetic acid [3]. The basic structure
€
[9a] and hence serves as a molecular probe. Racemic Troger's base
containing phenanthroline units are known to cleave DNA in the
presence of Cu2þ ions [11]. Proflavine type Troger's base has also
€
€
of Troger's base features a central bicyclic aliphatic diazocine unit
been used for enantiospecific binding to calf-thymus B-DNA se-
quences containing both A.T and G.C base pairs. Veale et al. re-
ported the synthesis and fluorescence imaging studies of 1,8-
fused with two arene rings, oriented approximately at right angles
to each other (V shaped) [4]. Troger's base also has C2-symmetry
€
€
and chirality that is provided by the two stereogenic bridgehead
nitrogen atoms (inability to invert) of the diazocine ring. The
naphthalimide analogues of Troger's base and illustrated their
rapid uptake by cancer cells [12]. However, limited studies have
€
€
unique geometry of Troger's base has been exploited for many
been reported on Troger's base derivatives as anticancer agents
applications in the field of supramolecular chemistry as molecular
[13].
Earlier, our group has reported the VilsmeiereHaack reaction of
€
Troger's base analogues resulting in an unusual functionalization of
methylene bridge of the diazocine unit [14]. In our continued in-
terest in developing small molecules as cytotoxic agents [15], we
* Corresponding authors.
€
E-mail addresses: manjula@iict.res.in, manjula_alla@yahoo.com (M. Alla),
anthony@iict.res.in (A. Addlagatta).
have expanded our chemistry on Troger's base scaffold in designing
http://dx.doi.org/10.1016/j.ejmech.2014.08.044
0223-5234/© 2014 Elsevier Masson SAS. All rights reserved.

40
B.R. Manda et al. / European Journal of Medicinal Chemistry 86 (2014) 39e47
2.2. Pharmacology
€
In vitro cytotoxicity of all the synthesized Troger's base de-
rivatives was evaluated by MTT-micro cultured tetrazolium assay
against a panel of three human cancer lines A549 (lung adenocar-
cinoma), MDAMB-231 (breast) and SK-N-SH (neuroblastoma). The
€
Fig. 1. Troger's base.
€
Fig. 2. Examples of biologically active Troger's base analogues.
and synthesizing novel derivatives. In this context, we have incor-
porated small heterocyclic groups like morpholine, piperidine,
imidazole, triazole, and tetrazole which are effective pharmaco-
phores into methylene bridge or as substitutions on aromatic ring
IC50 values i.e., the effective concentration at which 50% growth of
the cancer cells was inhibited, were calculated to evaluate the
anticancer activities. All the experiments were carried out in trip-
licates. Activity results are shown in Tables 1 and 2.
€
of Troger's base and evaluated them for anticancer activity. In first
As shown in Table 1, the first phase of compounds showed
moderate to significant cytotoxic activities on MDAMB-231 cell
line. The cytotoxicity of these compounds was found to be depen-
dent on the substituents present on the aromatic ring as well as on
phase, 18 compounds were synthesized. Based on their cytotoxic
activity, a set of 12 new compounds have been synthesized that
displayed improved efficacy against MDAMB-231 cell line.
€
€
the methylene bridge of Troger's base. Among the Troger's base
analogues with simple benzene ring substitutions it was found that
methylene bridge substitutions such as N,N-dimethylamino, N-
alkyl-N-arylamino and N-cycloalkylamino groups showed no
enhancement of activity on MDAMB-231 cell line. However, in N-
alkyl-N-arylamino substitutions, the activity was enhanced. Com-
pound 2b with N-methyl-N-p-tolyl amino group and compound 2h
with N-methyl-N-phenylamino group on methylene bridge were
2. Results and discussion
2.1. Chemistry
€
A series of methylene bridge substituted Troger's base analogues
with N,N-dimethylamino, N-alkyl-N-arylamino and N-cyclo-
alkylamino functionalities have been synthesized.
method for the synthesis of methylene bridge substituted Troger's
base derivatives that employs VilsmeiereHaack conditions has
been adopted. Accordingly, a series of Troger's base analogues were
prepared by the reaction of corresponding formamides with POCl3
(Scheme 1). Target compounds were obtained in good yields.
The crucial precursor 9, required for generation of various
benzene substitutions has been synthesized from commercially
available 4-nitrophenol in two steps i.e., by first reacting 4-
nitrophenol with 1,2-dibromoethane, followed by reduction of
eNO2 group. 4-(2-Bromoethoxy)aniline thus obtained was con-
most potent with IC50 values of 10.72
14.34 0.19 M, respectively. The other compounds in this series
2k, 2e, 2f, 2c, 3, and 2d have shown moderate inhibition with IC50
values 57.50 M, 61.79 M, 72.33 M, 78.14 M, 82.35 M, and
86.76 M respectively. No clear preference for benzene ring sub-
0.54 mM and
A
general
€
m
m
m
m
m
m
€
m
stitutions could be established but alkyl substitutions seem to have
no benefit.
However, none of the compounds in this phase were active
against A549 cell line. Among all the compounds, only compound 3
with piperidine as the bridge substituent and methyl groups on
€
aromatic rings of Troger's base has shown good inhibition against
SK-N-SH cell line with an IC50 of 12.21 0.13 mM. However, intro-
€
€
verted into Troger's base 9, using classic Troger's base formation
duction of morpholine on bridge or changing the substituents on
benzene ring did not improve the inhibition on this cell line.
Selective inhibition of MDAMB-231 cell line in first phase of the
synthesis has encouraged us to design molecules with increasing
conditions i.e., 37% formaldehyde solution in presence of HCl in
EtOH. A series of small heterocyclic ring substituted Troger's base
€
analogues 11(aei) were prepared by the condensation of 9 with
corresponding heteroaryl rings in presence of K2CO3 and acetoni-
trile solvent (Scheme 2). The products were obtained in 74e89%
yield.
With a view to increase the diversity of the library, functional-
ization of the methylene bridge of newly designed analogues was
taken up. The methylene bridge substitution of 9 was carried out
under classic VilsmeiereHaack conditions to afford 12 in 65%
yields. The targeted compounds 13(aec) (Scheme 3) were obtained
€
chain length on aromatic rings of Troger's base and incorporation of
heterocyclic units for the second phase. As shown in Table 2,
compounds 11c, 11d, 11i, 11h, and 13c have exhibited better cyto-
toxicity than the control compound doxorubicin against MDAMB-
231 cell line with IC50 values of 4.29 mM, 4.79 mM, 5.15 mM, 4.82 mM
and 5.80
m
M, respectively. Increase in the chain length on aromatic
€
rings of Troger's base and incorporating heterocyclic units has
indeed improved anticancer activity. Among the heterocycles
€
in good yield by the reaction of Troger's base 12 with corresponding
€
introduced on the Troger's base, five membered rings such as
heterocycles in presence of K2CO3 and acetonitrile (Scheme 3). The
new compounds thus synthesized are completely characterized by
their spectral data before proceeding for biological evaluation.
imidazole, triazole or tetrazole were not as effective as six
membered rings like morpholine, piperidine or piperazine.

B.R. Manda et al. / European Journal of Medicinal Chemistry 86 (2014) 39e47
41
Scheme 1. Synthesis of methylene bridged Troger's base analogues 2ae2l and 3e7. Reaction conditions: (i) DMF, POCl3, 0 ꢀC to r.t., 2e6 h; (ii) heterocyclic formamide, POCl3, r.t.,
4e6 h.
€
Scheme 2. Synthesis of Troger's base analogues 9 and 11ae11i. Reaction conditions: (i) 37% HCHO solution, HCl, EtOH, 0 ꢀC to r.t., 24 h; (ii) RH, K2CO3, CH3CN, reflux, 24 h.
€
Scheme 3. Synthesis of N,N-dimethylamino crowned Troger's base analogues 12 and 13(aec). Reaction conditions: (i) DMF, POCl3, 0 ꢀC to r.t., 5 h; (ii) RH, K2CO3, CH3CN, reflux, 24 h.
€
Morpholine (11c) substitution has brought about best inhibition of
MDAMB-231 cell line. However, no distinct affect of the methylene
bridge substitution was decipherable from the current study.
or N-cycloalkylamino units has no influence on the cytotoxicity
compared to N-alkyl-N-arylamino functionalization. Introduction
of six membered heterocycles with a chain on aromatic rings of
€
Troger's base resulted in better activity compared to five membered
heterocycles and the best activity was obtained with morpholine as
the substituent. Improved and promising anticancer activity of the
3. Conclusion
€
synthesized Troger's base compounds provides the basis for further
In summary, present work describes the synthesis of a series of
exploration of these molecules as therapeutics, specifically against
€
Troger's base analogues by extensive functionalization of both
breast cancer.
methylene bridge as well as benzene ring framework with various
heterocycles in two phases. All the compounds synthesized in the
first phase were tested for anticancer activity against A549,
MDAMB-231 and SK-N-SH cancer cell lines. Several compounds
from this phase showed selective activity against MDAMB-231 cell
line while only compound 3 inhibited the growth of SK-N-SH cell
line and none had any effect on A549 cell line. Several redesigned
compounds synthesized in the second phase were effective in-
hibitors against MDAMB-231 cell line and better than doxorubicin.
Methylene bridge functionalization either with N,N-dialkylamino
4. Experimental protocols
4.1. Materials and methods
All starting materials were obtained from the best known
commercial sources and used as received. All reactions were carried
out in anhydrous conditions. Organic layers were dried over
anhydrous Na2SO4. Thin layer chromatography (TLC) was

42
B.R. Manda et al. / European Journal of Medicinal Chemistry 86 (2014) 39e47
Table 1 (continued)
Table 1
€
IC50 values of Troger's base analogues 1a, 2(ael) and 3e7 on human cancer cell lines.
Entry Compound
IC50 values in
A549
mM
Entry Compound
IC50 values in
A549
mM
SK-N-SH
MDAMB-231
SK-N-SH
MDAMB-231
4
>100
>100
>100
1a
2a
>100
>100
>100
>100
>100
>100
>100
5
6
>100
>100
>100
>100
>100
>100
>100
>100
2b
>100
10.72 0.54
2c
2d
2e
2f
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
78.14 0.97
86.76 8.86
61.79 0.30
72.33 0.38
>100
7
>100
Doxorubicin
8.05 0.37 8.5 0.17
5.96 0.13
a
NT: not tested.
performed on Merck F254 precoated silica gel plates. Visualisation
was accomplished with UV light and/or iodine. Column chroma-
tography was performed on silica gel (60 ꢁ 120 mesh) on a glass
column. Melting points were determined in open capillaries and
are uncorrected. IR spectra were recorded on a FTIR spectrometer as
KBr pellets or neat, 1H and 13C NMR spectra for analytical purpose
were recorded in CDCl3 on a Bruker instrument at 300 MHz, Avance
instrument at 500 MHz and 75 MHz, respectively; chemical shifts
2g
2h
are expressed in d-scale downfield from TMS as an internal stan-
dard. Mass data (ESI) were recorded by quadruple mass spec-
trometry. HRMS data were obtained with the ESI ionization
sources.
14.34 0.19
€
4.2. General procedure for the synthesis of Troger's bases 2ae2l
and 3e7
For compounds 2ae2l, N,N-dimethylformamide (3 mmol) was
cooled in an ice bath and phosphorous oxychloride (3 mmol) added
drop wise. For compounds 3e7, VilsmeiereHaack reagent had to be
formed at 70 ꢀC. After formation of a yellow coloured paste, reac-
2i
>100
>100
>100
€
tion mixture was reached to room temperature. Troger's Base
(1 mmol) dissolved in 10 mL of dry dimethylformamide/dichloro-
methane was added and the reaction mixture stirred at room
temperature for 2e6 h. After completion of the reaction (monitored
by TLC), reaction was quenched with saturated sodium carbonate
solution. The aqueous layer was extracted with dichloromethane
(3 ꢁ 25 mL), the combined organic extracts were washed with
water (3 ꢁ 10 mL), dried and concentrated in vacuo. The crude
product was purified by column chromatography using EtOAc/
Hexane as eluent.
2j
NTa
NTa
NTa
2k
>100
>100
57.5 0.21
2l
3
>100
>100
>100
>100
4.2.1. Synthesis of ( )-2,8-dibromo-N-methyl-N-(p-tolyl)-6,12-
dihydro-5,11-methanodibenzo[b,f][1,5]diazocin-13-amine (2i)
2,8-Dibromo-6,12-dihydro-5,11-methano-dibenzo[b,f][1,5]diaz-
ocine (500 mg, 1.32 mmol) in 15 mL of CH2Cl2 was added to Vils-
meiereHaack reagent prepared by reacting N-methyl-N-(p-tolyl)
12.21 0.13 82.35 3.68
formamide (591 mg, 3.97 mmol) and POCl3 (371 mL, 3.97 mmol),

B.R. Manda et al. / European Journal of Medicinal Chemistry 86 (2014) 39e47
43
Table 2
IC50 values of Troger's base analogues 11(aei) and 13(aec) on MDAMB-231 cell line.
€
Entry
Compound name
IC50 values in mM on MDAMB-231
11a
13a
42.62 1.73
>100
11b
13b
>100
40.35 5.02
11c
13c
4.29 0.11
4.79 0.34
11d
5.15 0.09
11e
11f
>100
57.86 8.13
11g
11h
64.08 4.80
5.80 0.02
11i
4.82 0.20
5.96 0.13
Doxorubicin
and stirred at room temperature for 5 h. Crude product was purified
by column chromatography using 5% EtOAc in hexane as eluent
afforded 2i (433 mg, 66%) as a white foam. 1H NMR (500 MHz,
4.2.2. Synthesis of ( )-(2,8-diiodo-N,N-dimethyl-6,12-dihydro-
5,11-methano-dibenzo[b,f][1,5]diazocin-13-amine (2j)
2,8-Diiodo-6,12-dihydro-5,11-methano-dibenzo[b,f][1,5]diazo-
CDCl3)
d
(ppm): 7.29e7.24 (m, 2H), 7.07 (t, J ¼ 8.0 Hz, 3H), 7.0 (s,1H),
cine (500 mg, 1.05 mmol) in 8 mL of DMF was added to Vils-
6.98e6.91 (m, 4H), 4.97 (s, 1H), 4.70 (d, J ¼ 17.0 Hz, 1H), 4.44 (d,
meiereHaack reagent prepared by reacting DMF (246
mL,
J ¼ 17.0 Hz, 1H), 4.20 (d, J ¼ 17.0 Hz, 1H), 3.76 (d, J ¼ 16.0 Hz, 1H),
3.16 mmol) and POCl3 (296 L, 3.16 mmol), and stirred at room
m
2.79 (s, 3H), 2.30 (s, 3H); 13C NMR (75 MHz, CDCl3)
d
(ppm): 146.7,
temperature for 5 h. Crude product was purified by column chro-
matography using 5% EtOAc in hexane as eluent afforded 2j
(431 mg, 79%) as a white solid, mp 95e96 ꢀC. 1H NMR (500 MHz,
143.7,131.4,130.7, 130.5,130.4,130.1,129.3,129.2,129.1, 127.2, 126.9,
120.8, 116.8, 116.6, 84.9, 59.4, 50.7, 39.1, 20.7; IR (neat, cmꢂ1) 2963,
2865, 1474, 749; MS (ESI) m/z (%) 498 ([MþH], 100), HRMS (ESI)
calcd for C23H22Br2N3 498.01750, found 498.01830.
CDCl3)
d
(ppm): 7.43 (dd, J ¼ 13.3, 6.7 Hz, 2H), 7.24 (s, 1H), 7.18 (s,
1H), 6.85 (d, J ¼ 7.79 Hz, 1H), 6.81 (d, J ¼ 7.79 Hz, 1H), 4.57 (dd,

44
B.R. Manda et al. / European Journal of Medicinal Chemistry 86 (2014) 39e47
J ¼ 16.7, J ¼ 6.8 Hz, 2H), 4.12 (d, J ¼ 16.7 Hz, 1H), 3.80 (d, J ¼ 13.3 Hz,
2H), 2.37 (s, 6H); 13C NMR (75 MHz, CDCl3)
(ppm): 136.2, 136.1,
135.3, 135.2, 131.0, 130.6, 127.6, 127.3, 89.6, 87.6, 58.7, 51.0, 41.3; IR
(KBr, cmꢂ1) 2984, 2823, 1456, 750; MS (ESI) m/z (%) 518 ([MþH],
100), HRMS (ESI) calcd for C17H18N3I2 517.95846, found 517.95809.
HCl addition, the reaction mixture was stirred at r.t. for 24 h. After
completion of the reaction (monitored by TLC), the mixture was
concentrated under reduced pressure until one half of the original
volume remained and made basic with excess NH4OH. The aqueous
phase was extracted with dichloromethane (3 ꢁ 100 mL). The
combined organic layers were washed with saturated NaHCO3 so-
lution (2 ꢁ 100 mL) and dried over Na2SO4. The solvents were
removed under reduced pressure and purified by column chro-
matography using 30% ethyl acetate in hexane as eluent afforded 9
(2.93 g, 27%) as a white solid, mp 105e106 ꢀC. 1H NMR (300 MHz,
d
4.2.3. Synthesis of ( )-2,8-bromo-13-piperidin-1-yl-6,12-dihydro-
5,11-methano-dibenzo[b,f][1,5]diazocine (5)
2,8-Dibromo-6,12-dihydro-5,11-methano-dibenzo[b,f][1,5]diaz-
ocine (498 mg, 1.31 mmol) in 15 mL of DCM was added to Vils-
meiereHaack reagent prepared by reacting piperidine-1-
CDCl3)
d
(ppm): 7.06 (d, J ¼ 8.7 Hz, 2H), 6.75 (dd, J ¼ 2.6, 8.9 Hz, 2H),
carbaldehyde (446 mg, 3.95 mmol) and POCl3 (370
mL,
6.44 (d, J ¼ 2.5 Hz, 2H), 4.64 (d, J ¼ 16.6 Hz, 2H), 4.28 (s, 2H), 4.18 (t,
3.95 mmol) and stirred at room temperature for 6 h. Crude product
was purified by column chromatography using 5% EtOAc in hexane
as eluent afforded 5 (420 mg, 69%) as a white foam. 1H NMR
J ¼ 6.4 Hz, 4H), 4.07 (d, J ¼ 16.8 Hz, 2H), 3.57 (t, J ¼ 6.2 Hz, 4H); 13
C
NMR (75 MHz, CDCl3) d (ppm): 154.4,141.5,128.7,126.0,114.6,112.1,
68.0, 67.1, 58.8, 29.1; IR (neat, cmꢂ1) 2936, 2882, 1486, 1265, 1151,
(300 MHz, CDCl3)
d
(ppm): 7.28e7.19 (m, 2H), 7.06e6.88 (m, 4H),
1034, 750; MS (ESI) m/z (%) 469 ([MþH], 100), HRMS (ESI) calcd for
4.58 (d, J ¼ 16.6 Hz, 2H), 4.12 (d, J ¼ 16.8 Hz,1H), 3.93 (s,1H), 3.77 (d,
C19H21N2O2Br2 466.99643, found 466.99695.
J ¼ 16.4 Hz, 1H), 1.55e1.19 (m, 10H); 13C NMR (75 MHz, CDCl3)
€
d
(ppm): 147.6, 143.6, 131.0, 130.3, 130.0, 129.2, 129.1, 128.8, 127.2,
4.4. General procedure for the synthesis of Troger's bases 11(aei)
126.9, 116.5, 116.1, 88.3, 59.0, 51.2, 49.6, 25.6, 24.8; IR (neat, cmꢂ1
)
€
2965, 2821, 1464, 747; MS (ESI) m/z (%) 462 ([MþH], 100), HRMS
Troger's base 9 (1 mmol) was added to the mixture of amine
(ESI) calcd for C20H22N3Br2 464.03315, found 464.01435.
(2.2 mmol) and K2CO3 (3 mmol) in 15 mL of acetonitrile. The re-
action mixture was refluxed for 24 h. Acetonitrile was removed
under reduced pressure. Water was added (30 mL), reaction
mixture was extracted with dichloromethane (3 ꢁ 50 mL) and
combined organic extracts were washed with water (3 ꢁ 20 mL).
Solvent was removed under reduced pressure, dried over Na2SO4
and purified by column chromatography to afford the desired
product.
4.2.4. Synthesis of ( )-4-(2,8-diiodo-6,12-dihydro-5,11-
methanodibenzo[b,f][1,5]diazocin-13-yl)morpholine (6)
2,8-Diiodo-6,12-dihydro-5,11-methano-dibenzo[b,f][1,5]diazo-
cine (500 mg, 1.05 mmol) in 12 mL of DCM was added to Vils-
meiereHaack reagent prepared by reacting morpholine-1-
carbaldehyde (364 mg, 3.16 mmol), and POCl3 (296
mL,
3.16 mmol) and stirred at room temperature for 6 h Crude product
was purified by column chromatography using 5% EtOAc in hexane
as eluent afforded 6 (418 mg, 71%) as a light brown foam. 1H NMR
4.4.1. Synthesis of ( )-2,8-bis(2-(1H-imidazol-1-yl)ethoxy)-6,12-
dihydro-5,11-methanodibenzo[b,f][1,5]diazocine (11a)
€
(300 MHz, CDCl3)
d
(ppm): 7.44 (td, J ¼ 9.2 Hz, J ¼ 1.7 Hz, 2H),
Troger's base 9 (201 mg, 0.431 mmol) was added to the mixture
7.27e7.17 (m, 2H), 6.81 (dd, J ¼ 15.7, 8.3 Hz, 2H), 4.56 (dd, J ¼ 16.6,
9.1 Hz, 2H), 4.12 (d, J ¼ 16.8 Hz, 1H), 3.98 (s, 1H), 3.78 (d, J ¼ 16.6 Hz,
1H), 3.70e3.56 (m, 4H), 2.86e2.60 (m, 4H); 13C NMR (75 MHz,
of imidazole (65 mg, 0.948 mmol) and K2CO3 (178 mg, 1.29 mmol)
in 15 mL of acetonitrile, purified by column chromatography in
MeOH:EtOAc (1:9) as eluent afforded 11a (160 mg, 84%) as a white
CDCl3)
d
(ppm): 136.3, 136.1, 135.4, 135.1, 131.2, 130.6, 127.6, 127.2,
foam. 1H NMR (300 MHz, CDCl3)
d (ppm): 7.54 (s, 2H), 7.08e6.95
88.0, 87.7, 87.4, 66.8, 58.9, 51.0, 49.3; IR (neat, cmꢂ1) 2923, 2850,
1471, 1262, 1029, 749; MS (ESI) m/z (%) 560 ([MþH], 100), HRMS
(ESI) calcd for C19H20N3OI2 559.96902, found 559.96965.
(m, 6H), 6.69 (dd, J ¼ 2.5, 8.7 Hz, 2H), 6.38 (d, J ¼ 2.5 Hz, 2H), 4.61 (d,
J ¼ 16.8 Hz, 2H), 4.29e4.21 (m, 6H), 4.09 (t, J ¼ 5.0 Hz, 4H), 4.03 (d,
J ¼ 16.8 Hz, 2H); 13C NMR (75 MHz, CDCl3)
d (ppm): 153.8, 140.9,
136.8, 128.3, 128.1, 125.4, 118.8, 113.9, 111.2, 66.9, 66.4, 58.1, 45.8; IR
(neat, cmꢂ1) 2940, 1492, 1235, 1079, 747; MS (ESI) m/z (%) 443
([MþH], 100), HRMS (ESI) calcd for C25H27N6 O2 443.21900, found
443.21689.
4.2.5. Synthesis of ( )-2,8-diiodo-13-(piperidin-1-yl)-6,12-dihydro-
5,11-methanodibenzo[b,f][1,5]diazocine (7)
2,8-Diiodo-6,12-dihydro-5,11-methano-dibenzo[b,f][1,5]diazo-
cine (500 mg, 1.05 mmol) in 12 mL of DCM was added to Vils-
meiereHaack reagent prepared by reacting piperidine-1-
4.4.2. Synthesis of ( )-2,8-bis(2-(1H-1,2,4-triazol-1-yl)ethoxy)-
carbaldehyde (357 mg, 3.16 mmol), and POCl3 (296
m
L,
6,12-dihydro-5,11-methanodibenzo[b,f][1,5]diazocine (11b)
€
3.16 mmol) and stirred at room temperature for 6 h. Crude product
was purified by column chromatography using 5% EtOAc in hexane
as eluent afforded 7 (434 mg, 74%) as a light brown foam. 1H NMR
Troger's base 9 (192 mg, 0.412 mmol) was added to the mixture
of triazole (63 mg, 0.906 mmol) and K2CO3 (171 mg, 1.24 mmol) in
15 mL of acetonitrile, refluxed for 24 h, followed by column chro-
matography in MeOH:EtOAc (1:9) as eluent afforded 11b (146 mg,
80%) as a white solid, mp 161e162 ꢀC. 1H NMR (300 MHz, CDCl3)
(500 MHz, CDCl3)
d
(ppm): 7.42 (t, J ¼ 8.5 Hz, 2H), 7.29e7.15 (m, 2H),
6.81 (dd, J ¼ 15.3, 8.5 Hz, 2H), 4.56 (d, J ¼ 16.6 Hz, 2H), 4.11 (d,
J ¼ 16.6 Hz, 1H), 3.92 (s, 1H), 3.75 (d, J ¼ 16.4 Hz, 1H), 3.92 (s, 3H),
3.75 (d, J ¼ 16.6 Hz, 1H), 1.61e1.18 (m, 10H); 13C NMR (75 MHz,
d
(ppm): 8.16 (s, 2H), 7.91 (s, 2H), 7.02 (d, J ¼ 9.0 Hz, 2H), 6.67 (dd,
J ¼ 3.0, 9.0 Hz, 2H), 6.36 (d, J ¼ 3.0 Hz, 2H), 4.60 (d, J ¼ 17.0 Hz, 2H),
4.49 (t, J ¼ 5.0 Hz, 4H), 4.25 (s, 2H), 4.21 (t, J ¼ 5.0 Hz, 4H), 4.02 (d,
CDCl3)
d (ppm): 148.2, 144.3, 136.0, 135.8, 135.2, 134.9, 131.4, 130.7,
127.5, 127.2, 88.0, 87.5, 87.1, 58.8, 51.0, 49.6, 25.5, 24.8; IR (neat,
cmꢂ1) 2922, 2851, 1470, 1204, 747; MS (ESI) m/z (%) 558 ([MþH],
100), HRMS (ESI) calcd for C20H22N3I2 557.98976, found 557.98983.
J ¼ 17.0 Hz, 2H); 13C NMR (75 MHz, CDCl3)
d (ppm): 154.1, 151.8,
143.8, 141.5, 128.6, 125.9, 114.3, 111.7, 66.9, 65.6, 58.6, 49.0; IR (neat,
cmꢂ1) 2937, 2845, 1493, 1269, 1147, 1046, 736; MS (ESI) m/z (%) 445
([MþH], 100), HRMS (ESI) calcd for C23H25N8 O2 445.20950, found
445.20813.
4.3. Synthesis of ( )-2,8-bis(2-bromoethoxy)-6,12-dihydro-5,11-
methanodibenzo[b,f][1,5]diazocine (9)
4.4.3. Synthesis of ( )-2,8-bis(2-morpholinoethoxy)-6,12-dihydro-
To a mixture of 4-(2-bromoethoxy)aniline (5 gr, 23.2 mmol) in
20 mL ethanol was added 50 mL of 37% formaldehyde solution
followed by 45 mL of concentrated HCl (slow addition) at 0 ꢀC. After
5,11-methanodibenzo[b,f][1,5]diazocine (11c)
€
Troger's base 9 (202 mg, 0.433 mmol) was added to the mixture
of morpholine (83 mg, 0.954 mmol) and K2CO3 (179 mg, 1.30 mmol)

B.R. Manda et al. / European Journal of Medicinal Chemistry 86 (2014) 39e47
45
in 15 mL of acetonitrile, refluxed for 24 h, followed by column
4.4.7. Synthesis of ( )-2,8-bis(2-(4-benzylpiperidin-1-yl)ethoxy)-
chromatography in MeOH:EtOAc (1:9) as eluent afforded 11c
6,12-dihydro-5,11-methanodibenzo[b,f][1,5]diazocine (11g)
(183 mg, 88%) as a white solid, mp 125e126 ꢀC. 1H NMR (300 MHz,
Troger's base 9 (200 mg, 0.429 mmol) was added to the mixture
of 1-benzylpiperazine (165 mg, 0.944 mmol) and K2CO3 (177 mg,
1.28 mmol) in 15 mL of acetonitrile, purified by column chroma-
tography in MeOH:EtOAc (1:9) as eluent afforded 11g (176 mg, 76%)
€
CDCl3)
d
(ppm): 7.05 (d, J ¼ 8.7 Hz, 2H), 6.74 (dd, J ¼ 2.8, 8.7 Hz, 2H),
6.43 (d, J ¼ 2.6 Hz, 2H), 4.63 (d, J ¼ 16.8 Hz, 2H), 4.28 (s, 2H), 4.06 (d,
J ¼ 16.8 Hz, 2H), 4.0 (t, J ¼ 5.7 Hz, 4H), 3.71 (t, J ¼ 4.53 Hz, 8H), 2.74
(t, J ¼ 5.7 Hz, 4H), 2.53 (t, J ¼ 4.53 Hz, 8H); 13C NMR (75 MHz, CDCl3)
as a white solid, mp 115e116 ꢀC; 1H NMR (300 MHz, CDCl3)
d (ppm):
d
(ppm): 155.1, 141.0, 128.5, 125.8, 114.4, 111.7, 67.1, 66.7, 65.8, 58.7,
7.28e7.24 (m, 4H), 7.19e7.11 (m, 6H), 7.02 (d, J ¼ 8.9 Hz, 2H), 6.71
(dd, J ¼ 8.9, 2.9 Hz, 2H), 6.41 (d, J ¼ 2.9 Hz, 2H), 6.61 (d, J ¼ 2.9 Hz,
2H), 4.61 (d, J ¼ 16.6 Hz, 2H), 4.23 (s, 2H), 4.04 (d, J ¼ 16.8 Hz, 2H),
3.98 (t, J ¼ 5.9 Hz, 4H), 2.95e2.90 (m, 4H), 2.70 (t, J ¼ 5.9 Hz, 4H),
2.52 (d, J ¼ 7.0 Hz, 4H), 2.00 (td, J ¼ 2.3, 2.1 Hz, 6H), 1.65e1.58 (m,
57.5, 53.9; IR (neat, cmꢂ1) 2913, 2860, 1492, 1244, 1114, 775; MS
(ESI) m/z (%) 481 ([MþH], 100), HRMS (ESI) calcd for C27H37N4 O4
481.28093, found 481.27918.
4H), 1.36e1.28 (m, 4H) ppm; 13C NMR (75 MHz, CDCl3)
d (ppm):
4.4.4. Synthesis of ( )-di-tert-butyl 4,40-(((6,12-dihydro-5,11-
methanodibenzo[b,f][1,5]diazocine-2,8-diyl)bis(oxy))bis(ethane-
2,1-diyl))bis(piperazine-1-carboxylate) (11d)
155.2, 140.9, 140.5, 129.0, 128.5, 128.0, 125.8, 125.7, 114.4, 111.7, 67.1,
66.1, 58.8, 57.4, 54.2, 43.1, 37.6, 32.1; IR (neat, cmꢂ1) 2914, 2847,
1494, 1271, 1151, 1077, 741; MS (ESI) m/z (%) 657 ([MþH], 100),
HRMS (ESI) calcd for C43H53N4O2 657.41630, found 657.41725.
€
Troger's base 9 (180 mg, 0.386 mmol) was added to the mixture
of tert-butyl piperazine-1-carboxylate (158 mg, 0.849 mmol), and
K2CO3 (160 mg, 1.16 mmol) in 15 mL of acetonitrile, purified by
column chromatography in MeOH:EtOAc (1:9) as eluent afforded
11d (204 mg, 78%) as a white solid, mp 126e127 ꢀC. 1H NMR
4.4.8. Synthesis of ( )-2,8-bis(2-(4-(2-methoxyphenyl)piperazin-1-
yl)ethoxy)-6,12-dihydro-5,11-methanodibenzo[b,f][1,5]diazocine
(11h)
(300 MHz, CDCl3)
d
(ppm): 7.04 (d, J ¼ 8.9 Hz, 2H), 6.74 (dd,
€
Troger's base 9 (200 mg, 0.429 mmol) was added to the mixture
J ¼ 2.8 Hz, 2H), 6.43 (d, J ¼ 2.8 Hz, 2H), 4.63 (d, J ¼ 16.8 Hz, 2H), 4.28
(s, 2H), 4.06 (d, J ¼ 16.8 Hz, 2H), 3.99 (t, J ¼ 5.67 Hz, 4H), 3.42 (t,
J ¼ 4.91 Hz, 8H), 2.75 (t, J ¼ 5.67 Hz, 4H), 2.48 (t, J ¼ 4.91 Hz, 8H),
of 1-(2-methoxyphenyl)piperazine (181 mg, 0.944 mmol) and
K2CO3 (177 mg, 1.28 mmol) in 15 mL of acetonitrile, purified by
column chromatography in MeOH:EtOAc (1:9) as eluent afforded
11h (251 mg, 85%) as a white foam. 1H NMR (300 MHz, CDCl3)
1.45 (s, 18H) ppm; 13C NMR (75 MHz, CDCl3)
d (ppm): 154.97,
154.54, 140.86, 128.47, 125.79, 114.30, 111.57, 79.51, 67.02, 65.74,
58.68, 57.05, 53.14, 28.28 ppm; IR (neat, cmꢂ1) 2973, 2936, 1692,
1493, 1244, 1170, 756; MS (ESI) m/z (%) 679 ([MþH], 100), HRMS
(ESI) calcd for C37H55N6O6 679.41776, found 679.41780.
d
(ppm): 7.05 (d, J ¼ 8.7 Hz, 2H), 7.01e6.97 (m, 2H), 6.95e6.89 (m,
4H), 6.85 (dd, J ¼ 1.1 Hz, 2H), 6.76 (dd, J ¼ 2.7 Hz, 2H), 6.45 (d,
J ¼ 2.7 Hz, 2H), 4.64 (d, J ¼ 16.8 Hz, 2H), 4.23 (s, 2H), 4.14e4.02 (m,
8H), 3.85 (s, 6H), 3.15e3.04 (m, 8H), 2.82 (t, J ¼ 5.8 Hz, 4H),
2.79e2.71 (m, 6H); 13C NMR (75 MHz, CDCl3)
d (ppm): 155.1, 152.1,
141.1, 140.9, 128.5, 125.8, 122.8, 120.9, 118.1, 114.4, 111.7, 111.0, 67.1,
65.9, 58.8, 57.2, 55.2, 53.7, 50.4; IR (neat, cmꢂ1) 2931, 2867, 1496,
1239, 1055, 1024, 748; MS (ESI) m/z (%) 691 ([MþH], 100), HRMS
(ESI) calcd for C41H51N6O4 691.39663, found 691.39767.
4.4.5. Synthesis of ( )-2,8-bis(2-((1-phenyl-1H-tetrazol-5-yl)thio)
ethoxy)-6,12-dihydro-5,11-methanodibenzo[b,f][1,5]diazocine (11e)
€
Trogers base 9 (200 mg, 0.429 mmol) was added to the mixture
of 1-phenyl-1H-tetrazole-5-thiol (168 mg, 0.944 mmol) and K2CO3
(177 mg, 1.28 mmol) in 15 mL of acetonitrile, purified by column
chromatography in MeOH:EtOAc (1:9) as eluent afforded 11e
(230 mg, 81%) as a white solid, mp 73e74 ꢀC. 1H NMR (300 MHz,
4.4.9. Synthesis of ( )-2,8-bis(2-(4-(4-fluorophenyl)piperazin-1-yl)
ethoxy)-6,12-dihydro-5,11-methanodibenzo[b,f][1,5]diazocine (11i)
€
Troger's base 9 (127 mg, 0.272 mmol) was added to the mixture
CDCl3)
d
(ppm): 7.54 (s, 10H), 7.05 (d, J ¼ 8.7 Hz, 2H), 6.74 (dd,
of 1-(4-fluorophenyl)piperazine (108 mg, 0.599 mmol) and K2CO3
(113 mg, 0.817 mmol) in 15 mL of acetonitrile, purified by column
chromatography in MeOH:EtOAc (1:9) as eluent afforded 11i
(134 mg, 74%) as a white solid, mp 154e155 ꢀC. 1H NMR (300 MHz,
J ¼ 2.6, 8.7 Hz, 2H), 6.44 (d, J ¼ 2.8 Hz, 2H), 4.62 (d, J ¼ 17.2 Hz, 2H),
4.32e4.25 (m, 6H), 4.05 (d, J ¼ 17.2 Hz, 2H), 3.71 (t, J ¼ 5.7 Hz, 4H);
13C NMR (75 MHz, CDCl3)
d (ppm): 154.5, 153.9, 141.3, 133.4, 130.1,
129.8, 128.6, 126.0, 123.7, 114.5, 111.7, 67.1, 65.8, 58.7, 32.5; IR (neat,
cmꢂ1) 2925, 1496, 1242, 1151, 1028, 761; MS (ESI) m/z (%) 663
([MþH], 100), HRMS (ESI) calcd for C33H31N10O2S2 663.20674,
found 663.20815.
CDCl3)
d
(ppm): 7.05 (d, J ¼ 8.7 Hz, 2H), 6.98e6.93 (m, 4H),
6.89e6.84 (m, 8H), 6.76 (dd, J ¼ 8.7, 2.7 Hz, 2H), 6.45 (d, J ¼ 2.7 Hz,
2H), 4.64 (d, J ¼ 16.8 Hz, 2H), 4.29 (s, 2H), 4.10e4.02 (m, 6H), 3.12 (t,
J ¼ 4.9 Hz, 8H), 2.82 (t, J ¼ 5.3 Hz, 4H), 2.76e2.68 (m, 8H); 13C NMR
(75 MHz, CDCl3)
d (ppm): 158.7, 155.6, 155.1, 147.8, 141.0, 128.6,
4.4.6. Synthesis of ( )-2,8-bis(2-(4-((4-chlorophenyl)(phenyl)
methyl)piperazin-1-yl)ethoxy)-6,12-dihydro-5,11-methanodibenzo
[b,f][1,5]diazocine (11f)
125.9, 117.9, 117.7, 115.6, 115.3, 114.5, 111.7, 67.2, 65.9, 58.8, 57.1, 53.5,
50.0; IR (neat, cmꢂ1) 2937, 2823, 1509, 1491, 1230, 1152, 825; MS
(ESI) m/z (%) 667 ([MþH], 100), HRMS (ESI) calcd for C39H45N6O2F2
667.35666, found 667.35777.
€
Troger's base 9 (200 mg, 0.429 mmol) was added to the mixture
of 1-((4-chloro)(phenyl)methyl)piperazine (270 mg, 0.944 mmol)
and K2CO3 (178 mg, 1.28 mmol) in 15 mL of acetonitrile, purified by
column chromatography in MeOH:EtOAc (1:9) as eluent afforded
11f (278 mg, 74%) as a white foam. 1H NMR (300 MHz, CDCl3)
4.5. Synthesis of ( )-2,8-bis(2-bromoethoxy)-N,N-dimethyl-6,12-
dihydro-5,11-methanodibenzo[b,f][1,5]diazocin-13-amine (12)
€
d
(ppm): 7.39e7.14 (m,18H), 7.02 (d, J ¼ 8.9 Hz, 2H), 6.71 (dd, J ¼ 8.9,
Following the general procedure 4.2, Troger's base 9 (1 g,
2.6 Hz, 2H), 6.40 (d, J ¼ 2.5 Hz, 2H), 4.61 (d, J ¼ 16.8 Hz, 2H), 4.26 (s,
2H), 4.18 (s, 2H), 4.03 (d, J ¼ 16.9 Hz, 2H), 3.97 (t, J ¼ 5.7 Hz, 4H), 2.74
2.15 mmol) in 10 mL of DMF was added to VilsmeiereHaack reagent
prepared by reacting DMF (499 mL, 6.44 mmol), and POCl3 (603 mL,
6.44 mmol) and stirred at room temperature for 5 h. Crude product
was purified by column chromatography using 10% EtOAc in hexane
as eluent afforded 12 (709 mg, 65%) as a white foam. 1H NMR
(t, J ¼ 5.7 Hz, 4H), 2.62e2.30 (m, 14H), 1.78e1.69 (m, 2H) ppm; 13
C
NMR (75 MHz, CDCl3) d (ppm): 155.1, 142.1, 141.3, 140.9, 132.4, 129.1,
128.6, 128.5, 127.8, 127.1, 125.9, 114.4, 111.6, 75.4, 67.1, 65.9, 58.8,
57.0, 53.7, 51.7; IR (neat, cmꢂ1) 2936, 2809, 1490, 1243, 1154, 757;
MS (ESI) m/z (%) 879 ([MþH], 100), HRMS (ESI) calcd for
(300 MHz, CDCl3)
d
(ppm): 7.02 (dd, J ¼ 9.1, 8.3 Hz, 2H), 6.73 (td,
J ¼ 3.0, 2.3 Hz, 2H), 6.43 (dd, J ¼ 3.0, 2.3 Hz, 2H), 4.59 (d, J ¼ 16.6 Hz,
C
53H57N6O2Cl2 879.39146, found 879.39151.
1H), 4.55 (d, J ¼ 16.6 Hz, 1H), 4.20e4.07 (m, 5H), 3.84e3.69 (m, 5H),

46
B.R. Manda et al. / European Journal of Medicinal Chemistry 86 (2014) 39e47
3.59e3.51 (m, 1H), 2.40 (s, 6H); 13C NMR (75 MHz, CDCl3)
154.4, 154.2, 142.4, 138.2, 129.4, 129.2, 126.6, 126.3, 114.6, 114.3,
111.8, 111.7, 90.3, 68.1, 67.9, 59.5, 51.8, 41.4, 29.3, 29.2; MS (ESI) m/z
d
(ppm):
114.0, 111.5, 111.3, 90.4, 66.8, 65.9, 65.7, 59.6, 57.6, 53.9, 51.8, 41.4,
29.7 ppm; IR (neat, cmꢂ1) 2923, 2853, 1493, 1240, 1116, 1059, 755;
MS (ESI) m/z (%) 524 ([MþH], 100), HRMS (ESI) calcd for C29H42N5
O4 524.32313, found 524.32244.
(%) 512 ([MþH], 100), HRMS (ESI) calcd for
C21H26N3O2Br2
512.05428, found 512.03601.
4.7. Cytotoxicity against three cell lines
€
4.6. General procedure for the synthesis of Troger's bases 13(aec)
Cytotoxicity of synthesized compounds was tested against three
cell lines, human lung cancer cell line (A549), a human breast
cancer cell line (MDAMB-231) and a human neuroblastoma cell line
(SK-N-SH) by MTT-micro cultured tetrazolium assay method [16].
All the experiments were carried out in triplicates. All the three
types of cell lines were seeded to flat bottom 96 well plates
(10,000 cells/100 mL) and cultured in the medium containing 10%
serum, incubated for 24 h in a 5% CO2 humid chamber so that the
cells adhere to the surface.
€
Troger's base 12 (1 mmol) was added to the mixture of amine
(2.2 mmol) and K2CO3 (3 mmol) in 15 mL of acetonitrile. The re-
action mixture was refluxed for 24 h. Acetonitrile was removed
under reduced pressure. Water was added (30 mL), reaction
mixture was extracted with dichloromethane (3 ꢁ 50 mL) and
combined organic extracts were washed with water (3 ꢁ 20 mL).
Solvent was removed under reduced pressure, dried over Na2SO4
and purified by column chromatography to afford the desired
product.
3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bro-
mide (MTT) was dissolved in PBS at 5 mg/mL and sterile filtered.
Different concentrations of the compounds were added to the
4.6.1. Synthesis of ( )-2,8-bis(2-(1H-imidazol-1-yl)ethoxy)-N,N-
dimethyl-6,12-dihydro-5,11-methanodibenzo[b,f][1,5]diazocin-13-
amine (13a)
adhered cells. After 48 h MTT solution (10
the culture plate. Cells were further incubated in the CO2 chamber
for 2 h. Following this, media was removed and 100 L of DMSO was
mL per well) was added to
€
Troger's base 12 (200 mg, 0.393 mmol) was added to the
m
mixture of imidazole (59 mg, 0.864 mmol) and K2CO3 (163 mg,
1.18 mmol) in 15 mL of acetonitrile, purified by column chroma-
tography in MeOH:EtOAc (1:9) as eluent afforded 13a (154 mg, 80%)
added. Absorbance was measured at 562 nm in a multimode micro
plate reader (Tecan GENios).
as a white foam. 1H NMR (300 MHz, CDCl3)
d (ppm): 7.54 (s, 2H),
Acknowledgements
7.06e6.94 (m, 6H), 6.67(td, J ¼ 2.8, 2.6 Hz, 2H), 6.37 (dd, J ¼ 2.6 Hz,
2H), 4.60e4.49 (m, 2H), 4.29e4.20 (m, 4H), 4.13e4.04 (m, 5H),
3.80e3.71 (m, 2H), 2.38 (s, 6H) ppm; 13C NMR (75 MHz, CDCl3)
We are grateful to CSIR for financial support (XII Five Year Plan
Project SMILE). MBR and RJG would like to acknowledge the sup-
port from CSIR, New Delhi for Senior Research Fellowship.
d
(ppm): 155.0, 154.9, 142.0, 137.8, 129.3, 129.1, 126.4, 126.2, 114.4,
114.0, 111.5, 111.3, 90.4, 66.8, 65.9, 65.7, 59.6, 57.6, 53.9, 51.8, 41.4; IR
(neat, cmꢂ1) 2923, 2852, 1461, 1279, 1079, 771; MS (ESI) m/z (%) 486
([MþH], 100), HRMS (ESI) calcd for C27H32N7O2 486.26120, found
486.26251.
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2014.08.044.
4.6.2. Synthesis of ( )-2,8-bis(2-(1H-1,2,4-triazol-1-yl)ethoxy)-
N,N-dimethyl-6,12-dihydro-5,11-methanodibenzo[b,f][1,5]diazocin-
13-amine (13b)
References
€
Troger's base 12 (200 mg, 0.393 mmol) was added to the
€
[1] J. Troger, J. Prakt. Chem. 36 (1887) 225e245.
mixture of triazole (59 mg, 0.864 mmol) and K2CO3 (163 mg,
1.18 mmol) in 15 mL of acetonitrile, purified by column chroma-
tography in EtOAc as eluent afforded 13b (154 mg, 80%) as a white
[2] (a) M.A. Spielman, J. Am. Chem. Soc. 57 (1935) 583e585;
(b) E. Wagner, J. Am. Chem. Soc. 57 (1935) 1296e1298;
(c) T.R. Miller, E.C. Wagner, J. Am. Chem. Soc. 63 (1941) 832e836;
foam. 1H NMR (300 MHz, CDCl3)
d (ppm): 8.17 (s, 2H), 7.91 (d,
€
(d) M. Haring, Helv. Chim. Acta 46 (1963) 2970e2982.
[3] (a) C.S. Wilcox, Tetrahedron Lett. 26 (1985) 5749e5752;
(b) I. Sucholeiki, V. Lynch, L. Phan, C.S. Wilcox, J. Org. Chem. 53 (1988)
98e104;
J ¼ 2.3 Hz, 2H), 6.99 (dd, J ¼ 9.1 Hz, 2H), 6.66 (tdt, J ¼ 3.0, 2.3 Hz,
2H), 6.36 (dd, J ¼ 3.0, 2.3 Hz, 2H), 4.59e4.45 (m, 6H), 4.24e4.02 (m,
5H), 3.79e3.71 (m, 2H), 2.37 (s, 6H); 13C NMR (75 MHz, CDCl3)
(c) D.P. Becker, P.M. Finnegan, P.W. Collins, Tetrahedron Lett. 34 (1993)
1889e1892;
(d) U. Maitra, B.G. Bag, P. Rao, D. Powell, J. Chem. Soc. Perkin Trans. 1 (1995)
2049e2056;
d
(ppm): 154.1, 154.0, 151.9, 151.8, 143.7, 142.6, 129.2, 126.6, 126.4,
114.4, 114.1, 111.7, 111.4, 90.2, 65.8, 65.7, 59.4, 51.7, 49.2, 41.3; IR
(neat, cmꢂ1) 2925, 2837, 1472, 1258, 1035, 736; MS (ESI) m/z (%) 488
([MþH], 100), HRMS (ESI) calcd for C25H30N9O2 488.25170, found
488.25169.
(e) B.G. Bag, U. Maitra, Synth. Commun. 25 (1995) 1849e1856;
(f) J. Cudero, C. Pardo, M. Ramos, E. Gutierrez-Puebla, A. Monge, J. Elguero,
Tetrahedron 53 (1997) 2233e2240;
€
(g) J. Jensen, K. Warnmark, Synthesis (2001) 1873e1877;
€
(h) A. Hansson, J. Jensen, O.F. Wendt, K. Warnmark, Eur. J. Org. Chem. (2003)
3179e3188;
4.6.3. Synthesis of ( )-N,N-dimethyl-2,8-bis(2-morpholinoethoxy)-
6,12-dihydro-5,11-methanodibenzo[b,f][1,5]diazocin-13-amine
(13c)
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€
Troger's base 12 (200 mg, 0.393 mmol) was added to the
mixture of morpholine (59 mg, 0.864 mmol) and K2CO3 (163 mg,
1.18 mmol) in 15 mL of acetonitrile, purified by column chroma-
tography in MeOH:EtOAc (1:9) as eluent afforded 13c (160 mg, 78%)
as a white foam. 1H NMR (300 MHz, CDCl3)
d (ppm): 7.00 (dd,
J ¼ 9.065 Hz, 2H), 6.71 (td, J ¼ 3.022 Hz, 2H), 6.42 (d, J ¼ 3.022 Hz,
2H), 4.56 (dd, J ¼ 16.618 Hz, 2H), 4.11 (d, J ¼ 16.618 Hz, 1H),
4.03e3.95 (m, 4H), 3.83e3.59 (m, 10H), 2.79e2.68 (m, 4H),
2.61e2.45 (m, 8H), 2.39 (s, 6H) ppm; 13C NMR (75 MHz, CDCl3)
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€
€
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d
(ppm): 155.0, 154.9, 142.0, 137.8, 129.3, 129.1, 126.4, 126.2, 114.4,
7015e7041;

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