Synthesis and evaluation of new 1,2,3,4-tetrahydroisoquinoline analogs as antiglioma agents

Article abstract of DOI:10.1007/s00044-010-9356-8

Novel tetrahydroisoquinoline (THI) analogs were designed, synthesized, and their antiglioma activity was evaluated. The results showed that 6,8-dimethoxy-1-(2′-methoxybiphenyl-4-ylmethyl)-1,2,3,4- tetrahydroisoquinoline hydrochloride (25) demonstrated imp

Full text of DOI:10.1007/s00044-010-9356-8

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2011) 20:131–137
DOI 10.1007/s00044-010-9356-8
ORIGINAL RESEARCH
Synthesis and evaluation of new 1,2,3,4-tetrahydroisoquinoline
analogs as antiglioma agents
•
Renukadevi Patil Shivaputra Patil XiangDi Wang
•
•
•
Fei Ma William E. Orr Wei Li Charles R. Yates
•
•
•
•
Eldon E. Geisert Duane D. Miller
Received: 4 February 2010 / Accepted: 28 April 2010 / Published online: 25 May 2010
Ó Springer Science+Business Media, LLC 2010
Abstract Novel tetrahydroisoquinoline (THI) analogs
were designed, synthesized, and their antiglioma activity
was evaluated. The results showed that 6,8-dimethoxy-1-(20-
methoxybiphenyl-4-ylmethyl)-1,2,3,4-tetrahydroisoquino-
line hydrochloride (25)demonstrated improved potency, and
selectivity on C6 rat glioma vs cultured rat astrocytes (EC50
0.63 lM vs. 10.85 lM) compared to our recent lead mole-
cule EDL-155 (EC50 1.5 lM vs. 27.4 lM). The isomers of
25 were isolated using a semi-preparative high-performance
liquid chromatography (HPLC) method, and their in vitro
biological evaluation revealed that (?) 25 was the most
active, and it was nearly 21 fold more potent than (-) 25,
suggesting the antiglioma profile is influenced by stereo-
chemical factors.
primary brain tumors that arise within the central nervous
system in adults (Kleihues et al., 2000; Lefranc et al.,
2005). These are the deadliest of the brain cancers because
surgical excision of these tumors is extremely difficult due
to the invasive nature of tumors derived from glia (Bari-
naga, 1997). Glioblastoma Multiforme (GBM, WHO grade
IV) is the most aggressive form of the gliomas, and
accounts for nearly 60–70% of malignant gliomas (Maciej
et al., 2004). They occur most commonly in adults, ages
45–55, and affect more men than women. In the United
States, approximately 18,000 patients are diagnosed with
GBM each year (Kang et al., 2008), and the mean life
expectancy of these patients is approximately 1 year
(Grossman and Batara, 2004; Kanzawa et al., 2003; Lam
and Breakefield, 2001; Lopez-Gonzalez and Sotelo, 2000).
A common approach used in the treatment of GBM
involves surgery (Berger, 1994), radiation therapy (Shaw,
2000), and various chemotherapeutic regimens (Lesser and
Grossman, 1994). The mainstay for chemotherapy is a
DNA alkylating agent such as Carmustine (BCNU, 1),
Lomustine (CCNU, 2), Temozolamide (TMZ, 3), Mel-
phalan (4), Fluorouracil (5) (Fig. 1). Despite the combined
treatment approach of surgery, radiotherapy, and chemo-
therapy, there has been very little improvement in outcome
for patients with GBM. Among the recent therapeutic
approaches, only the combined therapy of TMZ and radi-
ation treatment in a limited number of patients produced
encouraging clinical results in long-term survival. Thus,
there is a critical need for new and more effective GBM
treatments. Hence, new and more effective chemothera-
peutic drugs are essential to add to the existing multimodal
GBM treatments.
Keywords Glioblastoma multiforme (GBM) ꢀ
Tetrahydroisoquinoline (THI) ꢀ Isomers ꢀ EDL-155 ꢀ
Antiglioma activity
Introduction
Gliomas constitute the most frequent and malignant form
of primary brain tumors. They account for more than 50%
of all brain tumors, and are the most common form of
R. Patil ꢀ S. Patil ꢀ F. Ma ꢀ W. Li ꢀ C. R. Yates ꢀ
D. D. Miller (&)
Department of Pharmaceutical Sciences, College of Pharmacy,
University of Tennessee Health Science Center, Memphis,
TN 38163, USA
e-mail: dmiller@uthsc.edu
Our group has discovered (Mohler et al., 2006) a series
of new biaryl 1,2,3,4-THI derivatives, and conformation-
ally flexible analogs that have potent antiglioma activity in
X. Wang ꢀ W. E. Orr ꢀ E. E. Geisert
Department of Ophthalmology, College of Medicine, University
of Tennessee Health Science Center, Memphis, TN 38163, USA
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Med Chem Res (2011) 20:131–137
Fig. 1 Structures of antiglioma
chemotherapeutic agents
comparison with clinically used antiglioma chemothera-
peutic agents such as BCNU, 5-fluorouracil, and melphalan
(Fig. 1). As a result we found a lead molecule racemic
1-biphenyl-4-ylmethyl-1,2,3,4-tetrahydroisoquinoline-6,7-
diol hydrochloride (EDL-155, Fig. 1), which demonstrated
selective cytotoxic activity against C6 rat glioma cells
relative to cultured rat astrocytes. We compared antiglioma
activity of EDL-155 with standard chemotherapeutic
agents such as BCNU and TMZ in in vitro experiment on
C6 rat glioma versus normal rat astrocytes (EDL-155 EC50
1.5 lM vs. 27.4 lM; BCNU EC50 4.8 lM vs. 54.8 lM;
TMZ EC50 16.5 lM vs. 51.8 lM) (Kang et al., 2008). The
higher potency of racemic EDL-155 prompted us to study
this class of compounds in more detail, and we have
focused on design, syntheses, and chiral resolution of novel
THI analogs. Toward this end, we designed, synthesized,
and screened a series of new 6,8-dihydroxy-THI analogs
for antiglioma activity. Among all these newly synthesized
compounds, THI analog 25 was the most potent antiglioma
agent. We also report here the chiral resolution of the most
potent compound 25 by a semi-preparative high-perfor-
mance liquid chromatography (HPLC) method with the
aim of elucidating the pharmacological profile of the pure
isomers.
anhydrous DMF to obtain compound 9 in excellent yield
(94%). The amide 9 was cyclized using the Bischler–
Napieralski reaction with POCl3 in CH3CN followed by
reduction with NaBH4 to obtain the free amine, which was
then treated with oxalic acid in MeOH to afford the oxalyl
salt (10). Compound 10 was treated with 1 N NaOH in
DCM, and the resulting free amine was allowed to react
with di-tert-butyldicarbonate to give N-Boc-6,8-dime-
thoxy-1,2,3,4-THI derivative (11). The hydrochloride salt
(12) separated as solid when compound 11 was stirred with
2 M HCl in ether at 0°C and allowed to warm to room
temperature. Reaction of 11 with 1 M BBr3 in DCM fur-
nished 6,8-dihydroxy-1,2,3,4-THI hydrobromide salt (13),
which was further reacted with di-tert-butyldicarbonate to
obtain the N-Boc analog of 6,8-dihydroxy-1,2,3,4-THI
(14).
Scheme 2 shows the synthesis of D-ring-modified 6,8-
dihydroxy-1,2,3,4-THI (resorcinol) analogs (compounds 23
and 25). Compounds 16–18 were synthesized according to
the procedure of compounds 9–11 using 4-bromophenyl-
acetic acid 15, and amine 8. Compound 18 was treated with
1 M BBr3 in DCM to get hydrobromide salt (19), which
was then reacted with di-tert-butyl dicarbonate to give
N-Boc-THI derivative (20) in good yield. Compounds 20
and 18 were coupled with 2-methoxyphenylboronic acid
(21) using Suzuki–Miyaura reaction conditions to obtain
the desired compounds 22 and 24, respectively. Finally, the
compounds 22 and 24 were stirred with 2 M HCl in ether
to afford the required hydrochloride salts 23 and 25 in good
yields.
Results and discussion
Chemistry
Target molecules were synthesized according to the
sequence of reactions shown in Schemes 1 and 2 as race-
mic mixtures. 2-Biphenyl-4-yl-N-2-(3,5-dimethoxyphenyl)
ethylacetamide (9) was prepared by reported procedure
(Mohler et al., 2006). Biphenyl-4-yl-acetic acid (7) was
reacted with 2-(3,5-dimethoxyphenyl)ethylamine (8) in
presence of diethylcyanophosphonate, and triethyl amine in
Biological evaluation
An in vitro assay was used to screen all the newly syn-
thesized racemic 1,2,3,4-THI analogs for their effects on
the growth of C6 rat glioma cells relative to cultured rat
astrocytes. In this study, we focused on modification of the
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Med Chem Res (2011) 20:131–137
133
Scheme 1 Reagents and
conditions: a Et3N,
(EtO)2P(O)CN, DMF; b POCl3,
CH3CN; c NaBH4,
(COOH)2ꢀ2H2O, MeOH; d 1 N
NaOH, DCM,
[(CH3)2CꢀCO2]2O, THF; e 2 M
HCl, Ether; f 1 M BBr3, DCM;
g Et3N, [(CH3)2CꢀCO2]2O, THF
Scheme 2 Reagents and
conditions: a Et3N,
(EtO)2P(O)CN, DMF; b POCl3,
CH3CN; c NaBH4,
(COOH)2ꢀ2H2O, MeOH; d 1 N
NaOH, DCM,
[(CH3)2CꢀCO2]2O, THF; e 1 M
BBr3, DCM; f Et3N,
[(CH3)2CꢀCO2]2O, THF; g
Pd(OAc)2, PPh3, Na2CO3, i-
PrOH; h 2 M HCl, Ether
A- and D-rings of THI to see the effect on potency. The A-
ring-modified analogs (12 and 13) have shown moderate
activity against C6 rat glioma as well as selectivity toward
astrocytes (12: EC50 2.31 lM vs. 8.95 lM; 13: EC50
2.09 lM vs. 11.92 lM), whereas compound 11 displayed
lower potency (EC50 7.54 lM), and no effect on astrocytes
but compound 14 showed small decrease in cytotoxicity
(EC50 4.97 lM). Overall the N-substitution lowered the
cytotoxicity as compared to corresponding amine salts. We
next turned our attention to modify the D-ring of THI. The
N-Boc-6,8-dihydroxy-THI 22 lowered activity, and selec-
tivity (EC50 7.34 lM vs. 67.51 lM), whereas correspond-
ing methoxy derivative 24 was much less active (EC50
59.71 lM), and showed no effect on astrocytes. Compound
23 demonstrated the moderate activity, and selectivity
(EC50 2.61 lM vs. 15.73 lM), and it was most comparable
to compound 13 (Table 1). However, compound 25 dis-
played marked increase in activity, and selectivity (EC50
0.63 lM vs. 10.85 lM). This compound was the most
potent, and selective THI analog in this study, and it
showed nearly 2.4-fold increase in the activity in com-
parison with our previous lead molecule EDL-155 (EC50
1.5 lM vs. 27.4 lM). The antiglioma studies were carried
out for all newly synthesized THI analogs including com-
pound 25 as racemic mixture, but stereoisomers often show
different pharmacological activities. Therefore, we
resolved the racemic mixture to investigate the biological
properties of each enantiomer of compound 25.
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Table 1 C6 glioma cytotoxic activity and selectivity of THI analogs
In summary, we successfully synthesized novel A-ring-,
and D-ring-modified 6,8-dihydroxy THI (resorcinol) ana-
logs, and evaluated for their antiglioma activity on C6 rat
glioma vs normal rat astrocytes. The D-ring-modified res-
orcinol derivative 25 demonstrated improved potency and
selectivity in our assay when compared to EDL-155.
Resolution of 25 by a semi-preparative chiral HPLC
method enabled us directly, and efficiently to obtain both
enantiomers with 100% optical purity. The high potency
and selectivity of (?) 25 suggests that the stereochemical
properties influence the pharmacobiological profile of this
class of compounds.
Compound
no.
EC50 lM C6
glioma
EC50 lM
astrocyte
11
7.54
No
effect
12
13
14
18
19
20
22
23
24
2.31
2.09
8.95
11.92
8.58
4.97
10.13
12.61
7.04
28.13
23.90
9.97
7.34
67.51
15.73
2.61
59.71
No
Experimental
effect
25
0.63
0.26
5.39
1.5
10.85
13.08
15.73
27.4
Chemistry
(?) 25
(-) 25
EDL-155
All the reagents and solvents were purchased from Aldrich,
and used without further purification. Melting points were
determined on a Fisher apparatus, and are uncorrected.
Proton NMR spectra were recorded on a Bruker ARX 300
spectrometer (300 MHz), and spectral data were consistent
with assigned structures. Chemical shifts were expressed in
ppm (d); coupling constants (J) are given in Hz. Mass
spectra were collected on a Brucker ESQUIRE electrospray/
ion trap instrument in the positive and negative modes.
Elemental analysis (C, H, N) was performed by Atlantic
Microlab, Inc. (Norcross, GA), and results were within
0.4% of the theoretical values for the formula given.
All the reactions were carried out using little modifica-
tion of reported procedures (Mohler et al., 2006; Nikulin
et al., 2006).
Chiral resolution by HPLC and optical rotation
It is well known that the enantiomers of chiral drugs gen-
erally show significant differences in their pharmacoki-
netics (PK) and pharmacodynamics (PD) and adverse
reactions. Therefore, with the aim of elucidating enantio-
pharmacological profile of compound 25, we performed the
chiral resolution of its precursor N-Boc-THI analog 24 by
HPLC method. We resolved the individual isomers by (R,
R) WHELK-01 chiral HPLC column (Regis technologies,
Morton Grove, IL), which enabled us to directly, and
efficiently obtain both enantiomers in nearly 100% optical
purity with 85:15 ratio of hexane and isopropanol (Fig. 2).
The first fraction eluted at 8.12 min, and second fraction
eluted at 15.00 min. The collected fractions from each
isomer were pooled and evaporated under vacuum to give
the residues as first fraction called isomer-I and second
fraction called as isomer-II. Purity of isomers-I and II were
100% (Fig. 2d, e). After resolution, both the isomers, I and
II of 24, were treated with 2 M HCl in ether to afford
corresponding hydrochloride salts 25-isomers-I & II,
respectively. We examined the specific rotations of
25-isomers-I & II in MeOH solution using DigiPol 781
automatic polarimeter, and their specific rotations were
[a]D = -35.0 and [a]D = ?40.2 (t = 25°C), respectively.
Biological studies revealed that (?) 25 was the most active,
and it was nearly 21 fold more potent than (-) 25 on C6 rat
glioma cell lines [(?) 25: EC50 0.26 lM; (-) 25: EC50
5.39 lM]. This confirmed that the antiglioma activity of
racemic-25 (0.63 lM) was due to primarily the (?) 25.
General procedure for the Suzuki–Miyaura coupling
reactions (Compounds 22, 24)
To a solution of compound (18/20) (1 mmol) in anhydrous
i-PrOH (15 ml), palladium (II)acetate (4 mol%), and tri-
phenylphosphine (8 mol%) were added, and the mixture
was stirred under argon at room temperature for 30 min. To
this mixture, 2-methoxy phenylboronic acid 21 (1.5 mmol),
and Na2CO3 (3 mmol) were added successively, and the
reaction mixture was refluxed for 16 h. After being cooled
and concentrated, the obtained residue was partitioned
between EtOAc and saturated NaHCO3 aqueous solution.
Two layers were separated, and the aqueous phase was
extracted with EtOAc. The combined organic layers were
washed with water followed by brine, and dried over
anhydrous Na2SO4.. The solvent was evaporated under
reduced pressure, and the crude product was purified by
flash column chromatography (Table 2).
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Med Chem Res (2011) 20:131–137
135
Fig. 2 Chiral separation of 24
using LC/DAD. UV spectrum of
isomer-I (a) and isomer-II (b).
Separation of racemic mixture
(c), separated isomer-I (d), and
separated isomer-II (e)
Cytotoxicity assay
flasks. C6 rat glioma cell line was purchased from ATCC
(American Type Culture Collection). Cells were grown in
BME with 10% fetal calf serum culturing media in a 37°C
incubator containing a humid 5% CO2 atmosphere. For the
compounds testing, the cells were trypsinized, and trans-
ferred to 96-well microtiter plates at approximate cell
density of 103 cells/well of C6 glioma, and 104 cells/well of
astrocytes. The cells were grown overnight in 200 ll of
10% FCS BME in a 37°C incubator containing a humid 5%
CO2 atmosphere. All newly synthesized compounds were
dissolved completely to make a 100 lM stock solution, and
diluted to produce a series of concentrations. Immediately
The normal astrocytes for negative control testing were
cultured from the cerebral cortex of 3–4 day old Sprague-
Dawley rat pups as described (McCarthy and DeVellis,
1978), and modified (Geisert and Stewart, 1991) procedure.
The animals were anesthetized by cold, and decapitated,
after which their brains were immediately removed. Placed
the cortices in a Petri-dish containing 10 ml of Hank’s
Balanced Salt Solution (HBSS), and the tissue in 20 ml of
0.1% trypsin in HBSS for 10 min. The astrocytes were
plated at a density of 5 9 103 cells/cm2 into T-75 culture
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Table 2 Physical properties and spectroscopic data of THI analogs
Comp.
no.
Yield
(%)
M.P.
(°C)
1H NMR (d6-DMSO)
Mass m/z
9
94
108–10
d 8.11 (bs, 1H, –NH), 7.64 (d, J = 7.8 Hz, 2H, ArH), 7.56 (d, J = 7.8 Hz, 2H, ArH), 398 [M ? Na]?
7.48–7.43 (m, 2H, ArH), 7.36 (d, J = 6.9 Hz, 1H, ArH), 7.30 (d, J = 7.5 Hz, 2H,
ArH), 6.36–6.33 (m, 3H, ArH), 3.70 (s, 6H, 2*OCH3), 3.43 (s, 2H, –CH2), 3.28–3.26
(m, 2H, –CH2), 2.65 (t, J = 7.2 Hz, 2H, –CH2)
10
73
80
78
181–83
109–11
124–26
d 8.44–8.21 (bs, 1H, NH), 7.68–7.65 (m, 5H, ArH), 7.50–7.44 (m, 2H, ArH), 7.39–7.36 360 [M–
(m, 2H, ArH), 6.49 (s, 1H, ArH), 6.45 (s, 1H, ArH), 4.77–4.73 (m, 1H, –CH), 3.77 (s,
3H, OCH3), 3.73 (s, 3H, OCH3), 3.52–3.44 (m, 2H, CH2), 3.28–3.05 (m, 4H, 2*–CH2)
(CO2H)2 ? H]?
482 [M ? Na]?
11a
12
d 7.62–7.18 (m, 9H, ArH), 6.47 and 6.44 (s, 1H, ArH), 6.35 and 6.33 (s, 1H, ArH),
5.40–5.38 and 5.24–5.22 (m, 1H, –CH), 3.89, 3.80 and 3.75 (s, 6H, 2*OCH3),
3.06–3.02 and 2.89–2.70 (m, 6H, 3*–CH2), 1.26 and 1.00 (s, 9H, [CH3]3)
d 9.29 (s, 1H, –NH2), 8.54 (s, 1H, –NH2), 7.62 (d, J = 7.2 Hz, 4H, ArH), 7.50–7.45 (m, 395 [M–
2H, ArH), 7.38 (d, J = 7.8 Hz, 3H, ArH), 6.50 (s, 1H, ArH), 6.45 (s, 1H, ArH), 4.76
(s, 1H, –CH), 3.77 (s, 3H, OCH3), 3.74 (s, 3H, OCH3), 3.21–3.14 (m, 4H, 2*–CH2),
3.02–2.94 (m, 2H, –CH2)
(HCl) ? H]?
13
92
67
238–40
d 9.99 (bs, 1H, ArOH), 9.38 (bs, 1H, ArOH), 9.08 (bs, 1H, –NH2), 8.22 (bs, 1H, –NH2), 332 [M–
7.70–7.67 (m, 4H, ArH), 7.50–7.26 (m, 5H, ArH), 6.30 (d, J = 2.1 Hz, 1H, ArH),
6.11 (d, J = 2.1 Hz, 1H, ArH), 4.70 (d, J = 8.1 Hz, 1H, –CH), 3.43–3.33 (m, 2H,
–CH2), 3.22–3.04 (m, 2H, –CH2), 2.93–2.80 (m, 2H, –CH2)
(HBr) ? H]?
14a
198–200
d 9.58 and 9.52 (bs, 1H, ArOH), 9.08 and 9.05 (bs, 1H, ArOH), 7.61–7.19 (m, 9H,
ArH), 6.23 and 6.21 (s, 1H, ArH), 6.03 and 6.00 (s, 1H, ArH), 5.36–5.33 and 5.20–
5.17 (m, 1H, –CH), 3.16–3.12 and 2.79–2.61 (m, 6H, 3*–CH2), 1.24 and 0.99 (s, 9H,
[CH3]3)
454 [M ? Na]?
16
17
93
85
86–88
d 8.10 (t, J = 5.1 Hz, 1H, –NH), 7.46 (d, J = 8.4 Hz, 2H, ArH), 7.16 (d, J = 8.1 Hz, 400 [M ? Na]?
2H, ArH), 6.33 (s, 3H, ArH), 3.70 (s, 6H, 2*OCH3), 3.36 (s, 2H, –CH2), 3.27 (q,
J = 7.2, 6.9 Hz, 2H, –CH2), 2.63 (t, J = 7.2 Hz, 2H, –CH2)
168–70
d 8.45–8.20 (bs, 1H, NH), 7.53 (d, J = 8.1 Hz, 2H, ArH), 7.21 (d, J = 8.4 Hz, 2H,
ArH), 6.46 (s, 1H, ArH), 6.42 (s, 1H, ArH), 4.70 (t, J = 6.6 Hz, 1H, –CH), 3.76
(s, 3H, –OCH3), 3.68 (s, 3H, –OCH3), 3.42–3.35 (m, 2H, –CH2), 3.11–2.93 (m, 4H,
2*–CH2)
362 [M–
(CO2H)2 ? H]?
18a
19
85
75
94–96
d 7.49–7.06 (m, 4H, ArH), 6.45 and 6.43 (s, 1H, ArH), 6.34 and 6.32 (s, 1H, ArH),
5.32–5.29 and 5.15–5.12 (m, 1H, –CH), 3.87, 3.79 and 3.74 (s, 6H, 2*OCH3),
2.99–2.94 and 2.80–2.61 (m, 6H, 3*–CH2), 1.26 and 1.04 (s, 9H, [CH3]3)
484 [M ? Na]?
252–54
d 9.94 (s, 1H, ArOH), 9.38 (s, 1H, ArOH), 9.06 (bs, 1H, –NH2), 8.26 (bs, 1H, –NH2), 334 [M–
7.56 (d, J = 7.5 Hz, 2H, ArH), 7.28 (d, J = 7.2 Hz, 2H, ArH), 6.27 (s, 1H, ArH),
6.10 (s, 1H, ArH), 4.64 (d, J = 7.8 Hz, 1H, –CH), 3.28–3.16 (m, 2H, –CH2),
3.09–3.01 (m, 2H, –CH2), 2.84–2.78 (m, 2H, –CH2)
(HBr) ? H]?
20a
22a
77
55
222–24
d 9.57 and 9.50 (s, 1H, ArOH), 9.08 and 9.05 (s, 1H, ArOH), 7.48–7.06 (m, 4H, ArH), 456 [M ? Na]?
6.19 and 6.17 (s, 1H, ArH), 6.03 and 5.99 (s, 1H, ArH), 5.28–5.25 and 5.11–5.09 (m,
1H, –CH), 3.28–3.04 and 2.77–2.57 (m, 6H, 3*–CH2), 1.25 and 1.04 (s, 9H, [CH3]3)
d 9.57 and 9.50 (s, 1H, ArOH), 9.07 and 9.04 (s, 1H, ArOH), 7.38–6.99 (m, 8H, ArH), 484 [M ? Na]?
6.22 and 6.20 (s, 1H, ArH), 6.03 and 6.01 (s, 1H, ArH), 5.38–5.35 and 5.22–5.19 (m,
1H, –CH), 3.80 and 3.74 (s, 3H, OCH3), 3.26–3.08 and 2.80–2.58 (m, 6H, 3*–CH2),
1.26 and 1.02 (s, 9H, [CH3]3)
200–202
23
75
210–12
d 10.05 (s, 1H, ArOH), 9.41 (s, 1H, ArOH), 9.25 (bs, 1H, –NH2), 8.45 (bs, 1H, –NH2), 362 [M–
7.48 (d, J = 7.8 Hz, 2H, ArH), 7.39 (d, J = 7.8 Hz, 2H, ArH), 7.35–7.27 (m, 2H,
ArH), 7.12 (d, J = 8.1 Hz, 1H, ArH), 7.06–7.01 (m, 1H, ArH), 6.33 (s, 1H, ArH),
6.11 (s, 1H, ArH), 4.67 (d, J = 8.7 Hz, 1H, –CH), 3.77 (s, 3H, OCH3), 3.35 (bs, 4H,
2*–CH2), 3.18–3.03 (m, 2H, –CH2)
(HCl) ? H]?
24a
25
51
80
126–28
140–42
d 7.40–7.00 (m, 8H, ArH), 6.45 and 6.43 (s, 1H, ArH), 6.35 and 6.33 (s, 1H, ArH),
5.41–5.39 and 5.26–5.22 (m, 1H, –CH), 3.89, 3.79 and 3.74 (s, 9H, 3*OCH3),
3.04–3.00 and 2.86–2.71 (m, 6H, 3*–CH2), 1.28 and 1.03 (s, 9H, [CH3]3)
512 [M ? Na]?
d 9.31 (s, 1H, –NH2), 8.57 (s, 1H, –NH2), 7.47 (d, J = 7.8 Hz, 2H, ArH), 7.38–7.27 (m, 390 [M–
4H, ArH), 7.12 (d, J = 8.1 Hz, 1H, ArH), 7.06–7.01 (m, 1H, ArH), 6.50 (s, 1H, ArH),
6.45 (s, 1H, ArH), 4.70 (bs, 1H, –CH), 3.76 (s, 6H, 2*OCH3), 3.73 (s, 3H, OCH3),
3.18–3.06 (m, 4H, 2*–CH2), 3.04–2.95 (m, 2H, –CH2)
(HCl) ? H]?
a
In the NMR spectrum, a mixture of conformers of 3:1 ratio was appeared (Nikulin et al., 2006)
123

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Acknowledgments The Authors acknowledge the financial support
from The ED laboratories and The Van Vleet Endowed Professorship
(DDM), Department of Pharmaceutical Sciences, College of Phar-
macy, The University of Tennessee Health science Center.
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