Synthesis, complexation studies and biological activity of some novel mono and tricyclic cyclophane amides and cyclophane sulfonamides

Article abstract of DOI:10.1016/j.tet.2011.10.046

A series of mono, tricyclic cyclophane tetraamides and cyclophane sulfonamides have been synthesized and characterized from spectral and XRD studies. All the cyclophane amides form charge transfer (CT) complex with TCNQ. The cyclophane amides show moderate to good anti-inflammatory activity. Some of them were active against Gram positive (Klebsiella pneumonia) and Gram negative (Escherichia coli and Staphylococcus aureus) human pathogens.

Full text of DOI:10.1016/j.tet.2011.10.046

Tetrahedron 67 (2011) 9669e9679
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Tetrahedron
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Synthesis, complexation studies and biological activity of some novel mono
and tricyclic cyclophane amides and cyclophane sulfonamides
,
b
Perumal Rajakumar a , Ramar Padmanabhan
*
a Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 600025, India
b Research and Development Centre, Orchid Chemicals and Pharmaceuticals Ltd., Sozhanganallur, Chennai 600119, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of mono, tricyclic cyclophane tetraamides and cyclophane sulfonamides have been synthesized
and characterized from spectral and XRD studies. All the cyclophane amides form charge transfer (CT)
complex with TCNQ. The cyclophane amides show moderate to good anti-inflammatory activity. Some of
them were active against Gram positive (Klebsiella pneumonia) and Gram negative (Escherichia coli and
Staphylococcus aureus) human pathogens.
Received 10 September 2011
Received in revised form 11 October 2011
Accepted 13 October 2011
Available online 20 October 2011
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Tricyclic amides
Tricyclic sulfonamides
Charge transfer complex
TCNQ
Anti-bacterial activity
Anti-inflammatory activity
1. Introduction
Cyclic peptides with fluorophore-tag are useful for the design of
Hg2þ sensors.8 Synthesis of amide-based supramolecular systems
The development of synthetic receptors for anions is of con-
siderable interest because of their potential biomedical and envi-
ronmental applications.1 The discovery of crown ethers led the
breakthrough in the field of molecular recognition.2 Synthesis of
aza-crown ether based cyclophanes with amide linkage would be
of greater interest due to their potential applications in the field of
material science, medicine, biology3 and such molecules strongly
bind with alkali metal ions also. The enhanced applications of aza
crown ethers in supramolecular chemistry4 have influenced the
synthetic chemist to modify the molecular structure. The most
important aspect of supramolecular chemistry is the hosteguest
complexation process. Hence the structures of basic crown ethers
were modified significantly to increase the selectivity and speci-
ficity of guest molecules for complexation. One of the key modifi-
cation is the replacement of oxygen donor atoms by sulfur and/or
by nitrogen atoms.5 The other significant modification is the in-
sertion of functional groups viz., amides and esters in the macro-
cyclic ring system.6
has been reported in the literature.9,10 Supramolecular amides are
also used as molecular clefts,11 molecular receptors,12 and in mo-
lecular recognition13 of biologically interacting substrates including
anti-HIV active macrocyclic amides.14 The chiral macrocyclic tet-
raamides and their transition metal complexes have also been re-
ported.15 Interaction between an electron donor and an electron
acceptor moiety in cyclophane amides could result in the formation
of either a charge transfer (CT) complex or
pep stacking inter-
actions.16e19 Such cyclophane amides are in general called as self-
complementary cyclophane amides. Developing cyclophane am-
ide systems, which exhibit CT complexation, metal complexa-
tion,20,21 and biological activity22 is an ever interesting and
challenging problem. Due to their structural versatility and op-
portunity for synthetic modifications, amide cyclophanes in-
corporating phenyl23 and m-terphenyl unit have received much
attention in the area of CT complexation, ion transportation studies,
and biological activity.24 Hence, it is of interest to synthesize and
study the CT complexation, metal complexation properties, and
biological activity of novel cyclophane amides. Recently, synthesis
of dicationic acridinophanes,25 quinolinophanes,26 carbazolo-
phanes,27 and imidazolophanes28 using various spacers like pyri-
dine, m-terphenyl, and chiral binaphthol has been reported from
our laboratory. Herein, we report the synthesis of monocyclic and
tricyclic cyclophane amides, sulfonamides 1e13 (Figs. 1 and 2) and
Synthesis of mixed aza-oxo-thia macrocyclic tetraamides and
their antimicrobial, cytotoxicity studies were recently reported.7
* Corresponding author. Tel.: þ91 44 2220 2810; e-mail address: perumalraja-
kumar@gmail.com (P. Rajakumar).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.10.046

9670
P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
O
S
HN
O
S
NH
O
O
O
O
N
O
O
NH
NH
HN
HN
NH
NH
HN
HN
NH
S
HN
S
O
O
O
N
O
O
O
O
O
3
2
1
O
O
O
O
O
O
N
N
N
N
N
N
N
N
N
N
N
N
N
O
N
O
O
O
O
O
6
5
4
O
S
N
O
S
O
O
N
N
S
O
N
S
O
O
O
7
Fig. 1. Structure of cyclophane amides and sulfonamides 1e7.
their charge transfer complexation studies with 7,7,8,8-
tetracyanoquinodimethane (TCNQ). We also wish to report the
preliminary biological evaluation of all the synthesized compounds
for their anti-inflammatory and anti-bacterial activities.
at d 47.1. The FTIR spectrum of 3 showed the sulfonyl stretching
frequency at 1631 cmꢀ1 and the mass spectrum showed the mo-
lecular ion peak ([MþH]þ) at m/z 677.6. Similarly the structure of
cyclophane amides 1 and 2 was confirmed from spectral and ana-
lytical data. All the new compounds gave satisfactory FTIR, 1H and
13C NMR, mass spectral, and elemental analysis.
2. Results and discussion
2.1. Chemistry
In order to test the synthetic utility of tetraamine cyclophane 14
for the synthesis of tricyclic cyclophane amides, 1.0 equiv of
cyclophane amine 14 was coupled with 2.0 equiv of each iso-
phthaloyl chloride, pyridine-2,6-dicarboxylic acid chloride,
diphenic acid chloride, and benzene-1,3-disulfonyl chloride in
presence of triethylamine in dry DCM at room temperature under
high dilution conditions. The reaction mixture after usual work-up
afforded the tricyclic cyclophane amides 4, 5, 6, and 7 in 65, 70, 50,
and 75% yields, respectively, after purification by column chroma-
tography (Scheme 2). The 1H NMR spectrum of cyclophane amide 5
displayed four sets of doublets for the N-methylene protons at
The synthetic pathway leading to monocyclic cyclophane am-
ides 1, 2 and sulfonamide 3 (Fig. 1) is outlined in Scheme 1. Reaction
of 1.0 equiv of m-xylylene diamine with 1.0 equiv of each iso-
phthaloyl chloride, pyridine-2,6-dicarboxylic acid chloride, and
benzene-1,3-disulfonyl chloride in presence of triethylamine in dry
dichloromethane at room temperature under high dilution condi-
tions afforded the cyclophane amides 1, 2 and sulfonamide 3 in
about 80, 80, and 60% yields, respectively (Scheme 1). The 1H NMR
spectrum of cyclophane sulfonamide 3 displayed the N-methylene
d
3.80, 5.00, 5.10, and 5.41. The rest of the aromatic protons
appeared between
6.95 and 7.94. In the 13C NMR spectrum of
cyclophane amide 5, the N-methylene carbons appeared at 50.8
and 55.0 and carbonyl carbon at 169.2. The FTIR spectrum of 5
protons as a doublet at
The rest of the aromatic protons appeared between
In the 13C NMR spectrum of 3, the N-methylene carbons appeared
d
4.21 and NH protons as a triplet at
d
8.37.
d
d
6.83 and 8.07.
d
d

P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
9671
O
O
HN
HN
NH
O
O
HN
NH
NH
N
N
NH
O
O
HN
O
O
9
8
O
O
O
S
HN
O
S
NH
NH
NH
HN
S
HN
S
O
O
O
O
O
O
10
11
O
N
N
N
N
O
O
O
O
O
O
N
N
N
O
N
13
12
Fig. 2. Structure of cyclophane amides and sulfonamides 8e13.
showed the carbonyl stretching frequency at 1631 cmꢀ1 and the
mass spectrum showed the molecular ion peak ([MþH]þ) at m/z
739.3. The tetraamide cyclophane 5 gave satisfactory elemental
analysis. The amide 5 was recrystallized from chloroform/acetoni-
trile mixture. XRD studies of compound 5 show that out of four
benzene rings, two of them are parallel to each other. Moreover, the
pyridine moieties are parallel to each other. XRD studies indicate
that intermolecular hydrogen bonding exists between cyclophane
amide 5 and water. The crystal parameters for cyclophane amide 5
are given in Table 1 in Supplementary data and ORTEP diagram is
shown in Fig. 3. Similarly the structure of the tricyclic amide
cyclophanes 4, 6 and sulfonamide 7 was also confirmed from
spectral and analytical data.
amides, sulfonamide with m-terphenyl spacer. The synthetic
pathway leading to monocyclic cyclophane amides 8, 9, 10 and
sulfonamide 11 (Fig. 2) is outlined in Scheme 3. In order to syn-
thesize cyclophane amides with large cavity size to study the
influence of cavity size on CT complexation and biological studies,
diamine 16 was prepared. Reaction of 1.0 equiv of m-terphenyl
dibromide 15 with 2.2 equiv of hexamine in dry chloroform at
reflux resulted in the formation of hexammonium salt, which on
further hydrolysis with hydrochloric acid in EtOH/H2O mixture at
reflux afforded diamine 16 in 90% yield. The 1H NMR spectrum of
diamine 16 displayed the N-methylene protons as a singlet at
d
3.93. The rest of the aromatic protons appeared in the region
d
7.40e7.79. In the 13C NMR spectrum of 16, the N-methylene
Electron rich cyclophanes with large cavities29 are known to
bind electron-deficient guest molecules effectively. Hence, we
focused our attention on the synthesis of monocyclic cyclophane
carbons appeared at d 45.4 and the mass spectrum showed the
molecular ion peak ([MþH]þ) at m/z 289.2. Reaction of 1.0 equiv
of m-terphenyl diamine 16 with 1.0 equiv of each isophthaloyl

9672
P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
9
8
i
ii
2
v
1
iv
NH2
NH2
iii
X
X
15
16
X = Br
i-iii
3
X = NH2
Scheme 1. Reagents and conditions: (i) isophthaloyl chloride, TEA, DCM, rt, 24 h, 1
(80%); (ii) pyridine-2,6-dicarboxylic acid chloride, TEA, DCM, rt, 24 h, 2 (80%); (iii)
benzene-1,3-disulfonyl chloride, TEA, DCM (dry), 24 h, 3 (60%).
vi
vii
5
4
10
11
ii
i
Scheme 3. Reagents and conditions: (i) hexamine, CHCl3, rt, 12 h; (ii) concd HCl, EtOH/
H2O, reflux, 3 h; (iii) NaOH/H2O, rt, 22 (90%); (iv) isophthaloyl chloride, TEA, DCM
(dry), 24 h, 8 (70%); (v) pyridine-2,6-dicarboxylic acid chloride, TEA, DCM (dry), 24 h, 9
(80%); (vi) biphenyl-4,40-dicarboxylic acid chloride, TEA, DCM (dry), 24 h, 10 (80%);
(vii) benzene-1,3-disulfonyl chloride, TEA, DCM (dry), 24 h, 11 (70%).
NH
NH
HN
HN
chloride, pyridine-2,6-dicarboxylic acid chloride, biphenyl-4,40-
dicarboxylic acid chloride, and benzene-1,3-disulfonyl chloride in
presence of triethylamine in dry dichloromethane at room tem-
perature under high dilution conditions afforded the cyclophane
amides, 8, 9, 10, and 11 in about 70, 80, 80, and 70% yields, re-
spectively (Scheme 3). The 1H NMR spectrum of cyclophane
amide 8 displayed the N-methylene protons as a broad singlet at
iv
iii
14
7
6
Scheme 2. Reagents and conditions: (i) isophthaloyl chloride, TEA, DCM, rt, 24 h, 4
(65%); (ii) pyridine-2,6-dicarboxylic acid chloride, TEA, DCM, rt, 24 h, 5 (70%); (iii)
diphenic acid chloride, TEA, DCM, rt, 24 h, 6 (50%); (iv) benzene-1,3-disulfonyl chlo-
ride, TEA, DCM, rt, 24 h, 75%.
d
4.54 and NH protons as a multiplet between
rest of the aromatic protons appeared in the region
In the 13C NMR spectrum of 8, the N-methylene carbons appeared
d
9.19 and 9.24. The
d
7.43e8.49.
Fig. 3. ORTEP diagram of cyclophane amide 5.

P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
9673
at
d
42.5 and the carbonyl carbon at
d
165.6 and 165.9. The FTIR
Reduction of cyclophane imine 17 with sodium borohydride in
toluene/THF/MeOH mixture at 0e5 ꢁC afforded secondary tetra-
amine cyclophane 18 in about 80% yield (Scheme 4). The 1H NMR
spectrum of tetraamine cyclophane 18 displayed the N-methylene
spectrum of 8 showed the carbonyl stretching frequency at
1641 cmꢀ1 and the mass spectrum showed the molecular ion
peak ([MꢀH]ꢀ) at m/z 835.6. Similarly the structure of the amide
cyclophanes 9, 10 and sulfonamide cyclophane 11 was also con-
firmed from spectral and analytical data.
In order to synthesis tricyclic cyclophane tetraamides 12 and 13,
the diamine 16 was used. Reaction of 1.0 equiv of m-terphenyl di-
amine 16 and 1.0 equiv of isophthalaldehyde in ethanol under high
dilution conditions at room temperature resulted in the formation
of cyclophane tetraimine 17 in 90% yield (Scheme 4). The product
slowly precipitated from the reaction mixture during the course of
the reaction and was used without further purification. The 1H
NMR spectrum of tetraimine cyclophane 17 displayed the N-
protons as a singlet at
between
7.27 and 7.71. In the 13C NMR spectrum of 18, the N-
methylene carbons appeared at 51.7 and 52.1 and the mass
d 3.85 and the aromatic protons appeared
d
d
spectrum showed the molecular ion peak ([MþH]þ) at m/z 781.5.
Cyclophane tetraamine 18 of 1.0 equiv was coupled with
2.2 equiv of diphenic acid chloride and biphenyl-4,40-dicarboxylic
acid chloride in presence of triethylamine in dry dichloromethane
at room temperature under high dilution conditions. The reaction
afforded the tricyclic cyclophane amides 12 and 13 in 45 and 50%
yields, respectively (Scheme 4). The 1H NMR spectrum of cyclo-
phane amide 12 displayed N-methylene protons as a pair of dou-
methylene protons as a singlet at
appeared as a singlet at 8.45 and the aromatic protons appeared
between
7.39 and 7.85. In the 13C NMR spectrum of 17, the N-
methylene carbons appeared and N]CH carbons at 64.9 and
d 4.85. The N]CH protons
d
blets at
d
d
3.80, 3.84, a quartet at
4.83 and 4.87. The rest of the aromatic protons appeared between
6.71 and 8.31. In the 13C NMR spectrum of cyclophane amide 12,
49.0 and 52.5 and carbonyl
d 4.62, and a pair of doublets at
d
d
d
161.6, respectively, and the mass spectrum showed the molecular
the N-methylene carbons appeared at
d
ion peak ([MþH]þ) at m/z 773.4.
carbon at d 170.7. The FTIR spectrum of 12 showed the carbonyl
stretching frequency at 1634 cmꢀ1 and the mass spectrum showed
the molecular ion peak ([MþH]þ) at m/z 1193.7. Similarly the
structure of tricyclic cyclophane amide 13 was confirmed from
spectral and analytical data.
2.2. Complexation studies
N
N
Cyclophane amides 1e13 form charge transfer complexes with
7,7,8,8-tetracyanoquinodimethane (TCNQ).30 Complexation studies
of compounds 1e13 with tetracyanoethylene (TCNE) and paraquat
(PQT) were not successful. Cyclophanes 1e13 show UVevis ab-
sorption maxima at 255.0, 258.0, 238.5, 225.5, 261.0, 221.5, 262.0,
255.0, 258.0, 270.5, 241.5, 255.5, and 257.5 nm, respectively. How-
ever, the acceptor TCNQ shows an absorption maximum at
395.0 nm. Cyclophanes, 1e13 form a charge transfer complex with
TCNQ as evidenced by the appearance of absorption maxima at
843.0, 842.5, 742.5, 843.5, 842.0, 742.0, 842.5, 743.5, 742.5, 742.5,
743.0, 743.0, and 743.5 nm, respectively (Table 1 and Fig. 4). The
studies were carried out as outlined below.
i
16
N
N
17
ii
A solution of TCNQ (4.9ꢂ10ꢀ6 M) in a 1:1 mixture of CHCl3/
CH3CN at various dilutions (1, 2, 3, 4, 5, and 6 mL) were prepared
and added to the solution of the cyclophane amide (2.34ꢂ10ꢀ5 M)
in a 1:1 mixture of CHCl3/CH3CN (3 mL) in a quartz cuvette of path
length 1 cm. The UVevis spectrum was also obtained for each of the
sample separately and the changes in the absorbance of CT bands
were recorded. The CT complexation study of 6 with various con-
centrations of TCNQ is shown in Table 2. The plot of (concentration
of cyclophane)/absorbance (Y/A) vs 1/concentration of guest (1/X)
HN
HN
NH
NH
iii
12
Table 1
lmax for cyclophane amides and TCNQ complex of cyclophane amides 1e13
Cyclophane
amide
lmax (nm) of
cyclophane amide
lmax (nm) of
TCNQ complex
1
2
3
4
5
6
7
8
255.0
258.0
238.5
225.5
261.0
221.5
262.0
255.0
258.0
270.5
241.5
255.5
257.5
843.0
842.5
742.5
843.5
842.0
742.0
842.5
743.5
742.5
742.5
743.0
743.0
743.5
18
iv
9
13
10
11
12
13
Scheme 4. Reagents and conditions: (i) isophthalaldehyde, ethanol, rt, 48 h (90%); (ii)
NaBH4, toluene/THF/MeOH, 0e5 ꢁC, 1 h, 18 (80%); (iii) diphenic acid chloride, TEA,
DCM, rt, 24 h, 12 (45%); (iv) biphenyl-4,40-dicarboxylic acid chloride, TEA, DCM, rt,
24 h, 13 (50%).

9674
P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
Cyclophane amide - 6
0.0014
0.0012
0.0010
0.0008
0.0006
0.0004
0.0002
0.0000
0
50000 100000 150000 200000 250000
1/X
Fig. 5. Plot between 1/X and Y/A for cyclophane amide 6.
Table 3
Complexation of TCNQ with cyclophane amides 1e13
Cyclophane amide
Ka (molꢀ1 dm3)
3
[Mꢀ1 cmꢀ1
]
r
1
2
3
4
5
6
7
8
6.34ꢂ103
1.22ꢂ104
8.06ꢂ104
3.79ꢂ104
1.57ꢂ104
7.60ꢂ104
1.11ꢂ104
8.75ꢂ104
1.03ꢂ105
4.64ꢂ103
1.49ꢂ105
6.65ꢂ104
1.32ꢂ105
2.48ꢂ104
1.68ꢂ104
5.96ꢂ103
1.80ꢂ104
2.03ꢂ104
3.18ꢂ103
2.34ꢂ104
5.16ꢂ103
4.46ꢂ103
4.51ꢂ103
4.77ꢂ103
6.87ꢂ103
2.54ꢂ103
0.9997
0.9981
0.9985
0.9991
0.9996
0.9993
0.9999
0.9998
0.9998
0.9999
0.9999
0.9984
0.9991
9
10
11
12
13
Fig. 4. Charge transfer complexation behavior of cyclophane amide 6 with variable
concentration of TCNQ.
2.3. Biological study
was linear (Fig. 5). BenesieHildebrand equation was employed to
calculate Ka values.30 From the slope and the intercept values, Ka
In vitro anti-inflammatory activity was studied by HRBC (human
red blood cells) membrane stabilization method.31 The lysosomal
enzymes released during inflammatory condition produce a variety
of disorders. The extracellular activity of these enzymes is said to be
related to acute or chronic inflammation. The anti-inflammatory
agent acts by either inhibiting the lysosomal enzymes or by stabi-
lizing the lysosomal membranes. The observed data showing the
anti-inflammatory activity of the compounds and the control drug
are given in Table 4. In the present study the anti-inflammatory
activity of these compounds was investigated using HRBC mem-
brane stabilization and prednisolone was used as a standard and
the results are tabulated (Table 4). The anti-inflammatory activities
of all the amide cyclophanes 1e13 are concentration dependent. At
higher concentration, the amide cyclophanes exhibit better anti-
inflammatory activity than at lower concentration. Compound 8
(Ka¼interceptꢂslopeꢀ1) and
3 (
3
¼interceptꢀ1) were evaluated. The
plot was linear suggesting that the predominate species in solution
as a 1:1 complex (Fig. 5).
The Ka, , and r values of the CT complexes formed from 1 to 13
3
with TCNQ are shown in Table 3. All the compounds showed above
effectively forms charge transfer complexes with TCNQ. Cyclo-
phane amide (relatively smaller cavity) 3, 6, and 4 bind TCNQ more
strongly than 5, 2, 7, and 1. However, compounds (larger cavity) 11,
13, and 9 bind TCNQ more strongly than 8, 12, and 10. The nitrogen
atoms of the pyridine ring in the cyclophane amides moderately
influence the binding ability. The sulfonyl groups at the annular
ring in the cyclophane amides also greatly influence the binding
ability. But the influence of other substituents like benzene and
biphenyl toward the binding ability is relatively less when com-
pared with other functional groups. Complexation studies of 1e13
with TCNE and PQT were not successful.
shows the maximum anti-inflammatory activity (89.56% at 400
mL) when compared to the reference drug prednisolone (95.24% at
400 g/mL).
mg/
m
The highest degree of anti-inflammatory activity of cyclophane
amides 1e13 were found to be 72.79, 68.96, 86.56, 74.70, 77.80,
84.30, 76.74, 89.56, 78.05, 62.66, 83.44, 83.77 and 79.31%, re-
Table 2
BenesieHildebrand treatment data of the CT complex formed between the cyclo-
phane amide, 6 and TCNQ
spectively, at 400 mg/mL (Table 4 and Fig. 6).
Concn of guest, [X] (M)
Absorbance, A
[Y]/A (M)
1/[X] (Mꢀ1
)
The anti-bacterial studies were carried out aseptically under
in vitro conditions by ‘cup plate method’.32 All the five cyclophane
amides exhibited different levels of anti-bacterial activity against
the four tested human pathogenic bacteria compared to DMSO as
control. The antimicrobial activities of five different newly syn-
thesized cyclophane amides were evaluated against four human
pathogenic bacteria such as, Escherichia coli, Staphylococcus aureus,
Klebsiella pneumonia, Pseudomonas aeruginosa. The biological
4.9ꢂ10ꢀ6
9.8ꢂ10ꢀ6
14.7ꢂ10ꢀ6
19.6ꢂ10ꢀ6
24.5ꢂ10ꢀ6
29.4ꢂ10ꢀ6
0.023
0.037
0.044
0.050
0.056
0.059
0.001161
0.000722
0.000607
0.000534
0.000477
0.000453
204,081
102,040
68,027
51,020
40,816
34,013
lmax¼742.0 nm; concentration of cyclophane amide, 6¼2.67ꢂ10ꢀ5 M.
Ka¼7.60ꢂ104 Mꢀ1
;
3
¼3.18ꢂ103 [Mꢀ1 cmꢀ1] and r¼0.9993.

P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
9675
Table 4
negative (E. coli and S. aureus) human pathogens. But they are not
active against Gram positive human pathogen P. aeruginosa.
In vitro anti-inflammatory activity of cyclophane amides 1e13 by HRBC membrane
stabilization
Cyclophane amide
Activity (% prevention of lysis)
50 g/mL 100 g/mL 200
4. Experimental
4.1. General
m
m
m
g/mL
400 mg/mL
1
2
3
4
5
6
7
8
9
10
11
12
65.94ꢃ0.36
61.56ꢃ0.27
57.93ꢃ0.16
68.56ꢃ0.24
72.48ꢃ0.42
74.25ꢃ0.25
37.48ꢃ0.42
59.42ꢃ0.89
69.43ꢃ0.23
47.73ꢃ0.33
73.35ꢃ0.52
38.83ꢃ0.14
62.29ꢃ0.16
57.94ꢃ0.39
68.34ꢃ0.61
63.57ꢃ0.43
63.12ꢃ0.49
71.78ꢃ0.33
73.26ꢃ0.13
76.64ꢃ0.23
58.85ꢃ0.31
75.30ꢃ0.29
74.09ꢃ0.56
48.53ꢃ0.21
76.22ꢃ0.47
66.90ꢃ0.54
69.48ꢃ0.31
84.87ꢃ0.36
70.94ꢃ0.50
67.68ꢃ0.31
71.57ꢃ0.19
73.84ꢃ0.49
74.89ꢃ0.29
77.93ꢃ0.16
71.28ꢃ0.34
86.62ꢃ0.21
77.60ꢃ0.22
56.86ꢃ0.39
80.84ꢃ0.97
79.16ꢃ0.31
73.44ꢃ0.41
91.01ꢃ0.45
72.79ꢃ0.34
68.96ꢃ0.22
86.56ꢃ0.12
74.70ꢃ0.10
77.80ꢃ0.28
84.30ꢃ0.38
76.74ꢃ0.15
89.56ꢃ0.42
78.05ꢃ0.15
62.66ꢃ0.27
83.44ꢃ0.57
83.77ꢃ0.24
79.31ꢃ0.59
95.24ꢃ0.21
All the reagents and solvents employed were of the best grade
available and were used without further purification. The melting
points were determined by using a Metler Toledo melting point
apparatus by open capillary tube method and were uncorrected.
Spectroscopic data were recorded by the following instruments:
UV/vis: Shimadzu 2550 spectrophotometer. IR: PerkineElmer se-
ries 2000 FTIR spectrophotometer. NMR: Bruker Avance 400 MHz.
Mass: ESIdPerkinElmer Sciex, API 3000 mass spectrometer and
FAB-mass spectra: Jeol SX 102/DA-6000 mass spectrometer. The
elemental analysis for the compounds was carried out using the
Elementar Vario EL III elemental analyzer (SIPRA LABS LTD.,
Hyderabad, India). Pre-coated silica gel plates from Merck were
used for TLC. Column chromatography was carried out using silica
gel (100e200 mesh) purchased from ACME.
13
Prednisolone
Each value represents meanꢃSD of three observations.
4.2. Procedure for the preparation of tetraimine
A solution of diamine (4.33 g, 15 mmol) in ethanol (400 mL) and
a solution of dialdehyde (2.02 g,15 mmol) in ethanol (400 mL) were
simultaneously added dropwise to a well stirred solution of ethanol
(800 mL) for 6e8 h. After the addition was complete, the reaction
mixture was stirred for another 48 h. The precipitated solid was
filtered, washed with ethanol, and dried.
4.2.1. Tetraimine 17. This product was obtained as off-white solid
(5.22 g, 90%). Found: C, 87.29; H, 5.81; N, 7.31. C56H44N4 requires C,
87.01; H, 5.74; N, 7.25%; mp 176 ꢁC; IR (KBr, cmꢀ1) 1698, 1642, 1600;
dH (400 MHz, CDCl3) 4.86 (s, 8H, CH2N), 7.39 (d, 8H, J¼8.2 Hz),
7.43e7.51 (m, 4H), 7.56 (d, 2H, J¼1.6 Hz), 7.57 (t, 2H, J¼1.4 Hz), 7.60
(d, 10H, J¼8.2 Hz), 7.75 (t, 2H, J¼1.4 Hz), 7.84 (2H, J¼1.6 Hz), 7.85
(2H, J¼1.8 Hz), 8.45 (s, 4H, CHN); dC (100 MHz, CDCl3) 64.9, 126.2,
127.6, 128.7, 129.1, 129.4, 130.0, 130.5, 136.7, 138.5, 140.1, 141.7, 161.6;
MS (ES) m/z: 773.4 [MþH]þ.
Fig. 6. In vitro anti-inflammatory activity of cyclophane amides 1e13.
screening results of cyclophane amides with 10% DMSO as control
and with commercial antibiotics viz. Gentamycin for E. coli, S. au-
reus, Ciprofloxacin for K. pneumonia and Cefotaxime for P. aerugi-
nosa are tabulated (Table 5) in the form of diameter of zone of
inhibition in mm.
4.3. General procedure for the preparation of tetraamines
Further the anti-bacterial activity of the test compound was
dose dependent and it was remarkable at higher concentration. The
diameter of the zone of inhibition of amides 1e7 against bacterial
human pathogens is determined by the cup plate method between
Sodium borohydride (40 mmol) was added to a solution of tet-
raimine (6.5 mmol) in mixture of toluene (375 mL), THF (375 mL),
andmethanol(375 mL)at0e5 ꢁC. Thereactionmixturewasstirredat
0e5 ꢁC for 4 h. To the reaction mixture cold water (750 mL) was
added followed by DCM (750 mL). The layers were separated and
aqueous layer was extracted with DCM (2ꢂ250 mL). The combined
organic layers were washed with brine solution and then dried over
anhydrous potassium carbonate. Removal of the DCM under reduced
pressure gave the corresponding cyclophane tetraamine as a crude
material, which was purified by column chromatography (SiO2).
250 and 2000 mg/mL. The cyclophane amides 4 and 5 show mod-
erate activity against S. aureus. However, cyclophane amides 1e7
did not show any activity against P. aeruginosa. Cyclophane amides
6 and 7 showed remarkable activity against K. pneumonia species
whereas compound 3 showed moderate activity. However, cyclo-
phane amides 1 and 2 show activity in the range of 11.0e12.0
against E. coli (Table 5).
4.3.1. Tetraamine 15. The crude product was purified by column
chromatography (1% MeOH/CHCl3) to give the tetraamine 15 as off-
white solid (2.45 g, 80%), Found: C, 80.86; H, 7.68; N,11.81. C32H36N4
requires C, 80.63; H, 7.61; N, 11.75%; Rf (1% MeOH/CHCl3) 0.40; mp
147 ꢁC; IR (KBr, cmꢀ1) 1442; dH (400 MHz, CDCl3) 1.65 (br s, 4H, NH),
3.78 (s, 16H, CH2N), 7.20 (t, 2H, J¼1.6 Hz), 7.22 (s, 6H), 7.26e7.29 (m,
8H); dC (100 MHz, CDCl3) 53.8, 127.2, 128.0, 128.6, 140.6; MS (ES) m/
z: 477.2 [MþH]þ.
3. Conclusion
In conclusion, we have synthesized various monocyclic and
tricyclic cyclophane amides, sulfonamides with small and large
cavities. Charge transfer complexation studies of all the cyclophane
amides were carried out with TCNQ. Cyclophane amide with rela-
tively large cavity binds TCNQ more strongly than cyclophanes with
smaller cavity. Complexation studies of 1e13 with TCNE and PQT
were not successful. Some of the synthesized cyclophane amides
were active against Gram positive (K. pneumonia) and Gram
4.3.2. Tetraamine 18. The crude product was purified by column
chromatography (1% MeOH/CHCl3) to give the tetraamine 18 as off-
white solid (2.45 g, 80%). Found: C, 86.60; H, 6.82; N, 7.28. C56H52N4

9676
P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
Table 5
Anti-bacterial activity of cyclophane amides 1e13 by cup plate method
Cyclophane amide
Concentration in
m
g/mL
Diameter of zone of inhibition in mm
E. coli
Staphylococcus aureus
Klebsiella pneumonia
Pseudomonas aeruginosa
1
250
500
1000
2000
d
d
d
d
d
d
d
d
d
d
d
d
d
d
11.00ꢃ1.00
12.03ꢃ1.04
2
250
500
1000
2000
d
d
d
d
d
d
d
d
d
d
d
d
d
d
11.00ꢃ0.57
12.10ꢃ1.00
3
250
500
1000
2000
d
d
d
d
d
d
d
d
11.00ꢃ0.63
12.00ꢃ0.55
12.00ꢃ1.05
13.30ꢃ0.57
d
d
d
d
4
250
500
1000
2000
d
d
d
d
12.00ꢃ1.00
12.00ꢃ1.15
13.00ꢃ1.00
14.00ꢃ1.01
d
d
d
d
d
d
d
d
5
250
500
1000
2000
d
d
d
d
11.00ꢃ1.02
12.00ꢃ0.58
14.00ꢃ0.56
15.00ꢃ0.58
d
d
d
d
d
d
d
d
6
250
500
1000
2000
d
d
d
d
d
d
d
d
14.10ꢃ1.02
d
d
d
d
15.00ꢃ0.55
d
d
7
250
500
1000
2000
d
d
d
d
d
d
d
d
10.00ꢃ1.03
12.00ꢃ1.02
15.00ꢃ1.00
15.33ꢃ0.56
d
d
d
d
Standard
250
20.00ꢃ0.58
27.00ꢃ1.00
18.00ꢃ0.56
16.00ꢃ1.00
Each value represents meanꢃSD of three observations.
requires C, 86.12; H, 6.71; N, 7.17%; Rf (1% MeOH/CHCl3) 0.55; mp
168 ꢁC; IR (KBr, cmꢀ1) 1642; dH (400 MHz, CDCl3) 1.72 (br s, 4H, NH),
3.85 (s, 16H, CH2N), 7.27 (merged with CDCl3, 3H), 7.30e7.35 (m,
5H), 7.39 (d, 8H, J¼7.9 Hz), 7.43 (d, 2H, J¼6.8 Hz), 7.49 (d, 4H,
J¼7.5 Hz), 7.54 (d, 8H, J¼7.9 Hz), 7.71 (s, 2H); dC (100 MHz, DMSO-
d6) 51.7, 52.1, 124.8, 125.5, 126.5, 126.6, 127.6, 128.0, 128.6, 128.8,
129.4, 138.5, 139.8, 140.2, 140.7; MS (ES) m/z: 781.5 [MþH]þ.
128.0,128.3,129.8,134.1,134.5,139.6,139.8,165.3,165.8; MS (ES) m/
z: 533 [MþH]þ.
4.4.2. Cyclophane amide 2. The crude product was purified by col-
umn chromatography (5% MeOH/CHCl3) to give the cyclophane am-
ide 2 as off-white solid (1.56 g, 80%). Found: C, 67.56; H, 4.98; N,15.93.
C30H26N6O4 requires C, 67.40; H, 4.90; N,15.72%; Rf (5% MeOH/CHCl3)
0.35; mp 259 ꢁC; IR (KBr, cmꢀ1) 1658, 1534, 1445; dH (400 MHz,
DMSO-d6) 4.48 (br s, 8H, CH2N), 7.11e7.21 (m, 8H), 8.06e8.18 (m, 6H),
9.80 (br s, 4H, NH); dC (100 MHz, DMSO-d6) 42.1, 124.3, 125.5, 128.4,
139.3, 139.5, 148.5, 163.3; MS (FABþ) m/z: 534 [M]þ.
4.4. General procedure for the synthesis of cyclophane
amides
A solution of diamine (7.3 mmol) in dry dichloromethane
(400 mL) and a solution of the corresponding diacid chloride
(7.3 mmol)/disulfonyl chloride (7.3 mmol) in dichloromethane
(400 mL) were simultaneously added dropwise to a well stirred
solution of triethylamine (23.7 mmol) in dry dichloromethane
(1000 mL) for 8 h. After the addition was complete, the reaction
mixture was stirred for another 24 h. The solvent was removed at
reduced pressure and the solid obtained was washed with water
(2ꢂ200 mL) to remove triethylammonium chloride, which was
purified by column chromatography (SiO2).
4.4.3. Cyclophane sulfonamide 3. The crude product was purified
by column chromatography (5% MeOH/CHCl3) to give the
cyclophane amide 3 as off-white solid (1.49 g, 60%). Found: C,
49.91; H, 4.23; N, 8.35. C28H28N4O8S4 requires C, 49.69; H, 4.17;
N, 8.28%; Rf (5% MeOH/CHCl3) 0.40; mp 250 ꢁC (decomposed); IR
(KBr, cmꢀ1) 1631, 1455, 1424; dH (400 MHz, DMSO-d6) 4.21 (d,
8H, J¼6.2 Hz, CH2N), 6.83 (d, 4H, J¼7.4 Hz), 6.91 (t, 2H, J¼7.6 Hz),
7.14 (s, 2H), 7.34 (t, 2H, J¼7.8 Hz), 7.53 (d, 4H, J¼7.7 Hz), 8.07 (s,
2H), 8.37 (t, 4H, J¼6.2 Hz, NH); dC (100 MHz, DMSO-d6) 47.1,
127.5, 129.1, 129.4, 129.8, 130.9, 133.6, 141.8; MS (ES) m/z: 677.6
[MþH]þ.
4.4.1. Cyclophane amide 1. The crude product was purified by col-
umn chromatography (5% MeOH/CHCl3) to give the cyclophane
amide 1 as off-white solid (1.56 g, 80%). Found: C, 72.46; H, 5.38; N,
10.61. C32H28N4O4 requires C, 72.16; H, 5.30; N, 10.52%; Rf (5%
MeOH/CHCl3) 0.40; mp >370 ꢁC; IR (KBr, cmꢀ1) 1638, 1542, 1303;
dH (400 MHz, DMSO-d6) 4.44 (d, 8H, J¼5.9 Hz, CH2N), 7.19e7.30 (m,
8H), 7.48 (t, 2H, J¼7.7 Hz), 7.95e7.99 (m, 4H), 8.28 (s, 2H), 9.08 (t,
4H, J¼5.8 Hz, NH); dC (100 MHz, DMSO-d6) 42.7, 125.2, 126.1, 126.6,
4.4.4. Cyclophane amide 8. The crude product was purified by col-
umn chromatography (5% MeOH/CHCl3) to give the cyclophane
amide 8 as off-white solid (1.22 g, 80%). Found: C, 80.56; H, 5.36; N,
6.75. C54H42N6O4 requires C, 80.36; H, 5.30; N, 6.69%; Rf (5% MeOH/
CHCl3) 0.45;mp185 ꢁC; IR (KBr, cmꢀ1) 1641,1534,1477; dH (400 MHz,
DMSO-d6) 4.54 (br s, 8H, CH2N), 7.43 (d, 8H, J¼6.3 Hz), 7.53 (t, 2H,
J¼7.5 Hz), 7.60e7.63 (m, 6H), 7.67e7.77 (m, 7H), 7.79(s,1H), 7.85 (brs,

P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
9677
1H), 8.05e8.11 (m, 4H), 8.31 (d,1H, J¼2.1 Hz), 8.45 (s,1H), 8.49 (s,1H),
9.19e9.24 (m, 4H, NH); dC (100 MHz, DMSO-d6) 42.5, 124.9, 125.6,
126.8,126.9,128.0,128.1, 129.5,129.9,130.0,131.9, 134.4,134.6,138.7,
139.0, 139.1, 140.7, 165.6, 165.9; MS (ES) m/z: 835.6 [Mꢀ1].
130.7, 131.2, 136.3, 137.4, 137.5, 140.3, 160.7, 170.1, 172.7, 174.3; MS
(ES) m/z: 737.2 [MþH]þ.
4.5.2. Cyclophane amide 5. The crude product was purified by
column chromatography (2% MeOH/CHCl3) to give the cyclophane
amide 5 as off-white solid (0.54 g, 70%). Found: C, 74.92; H, 5.31; N,
11.47. C46H38N6O4 requires C, 74.78; H, 5.18; N, 11.37%; Rf (2% MeOH/
CHCl3) 0.40; mp 370 ꢁC (decomposed); IR (KBr, cmꢀ1) 1631,1421; dH
(400 MHz, CDCl3) 3.80 (d, 4H, J¼14.2 Hz, CH2N), 5.00 (d, 4H,
J¼15.7 Hz, CH2N), 5.10 (d, 4H, J¼15.5 Hz, CH2N), 5.41 (d, 4H,
J¼14.1 Hz, CH2N), 6.96 (t, 6H, J¼7.5 Hz), 7.06 (d, 4H, J¼6.8 Hz),
7.23e7.25 (m, 2H), 7.37 (s, 2H), 7.94 (t, 8H, J¼12.8 Hz); dC (100 MHz,
CDCl3) 50.8, 55.0, 125.7, 126.2, 127.0, 127.5, 128.1, 128.5, 129.1, 137.1,
138.3, 138.6, 152.4, 169.2; MS (ES) m/z: 739.3 [MþH]þ.
4.4.5. Cyclophane amide 9. The crude product was purified by
column chromatography (5% MeOH/CHCl3) to give the cyclophane
amide 9 as off-white solid (1.22 g, 80%). Found: C, 77.56; H, 5.15; N,
10.07. C56H44N4O4 requires C, 77.31; H, 5.05; N, 10.02%; Rf (5%
MeOH/CHCl3) 0.40; mp 198 ꢁC; IR (KBr, cmꢀ1) 1663, 1530, 1444; dH
(400 MHz, DMSO-d6) 4.65 (br s, 8H, CH2N), 7.30e7.48 (m, 9H),
7.52e7.61 (m, 4H), 7.68e7.75 (m, 8H), 7.78e7.86 (m, 2H), 8.21e8.32
(m, 7H), 9.97 (br s, 4H, NH); dC (100 MHz, DMSO-d6) 42.1, 124.6,
124.9, 125.0, 125.5, 126.9, 127.7, 128.1, 128.2, 129.5, 138.8, 139.6,
139.9, 140.6, 148.7, 149.3, 163.4; MS (ES) m/z: 838 [M]þ.
4.5.3. Cyclophane amide 6. The crude product was purified by
column chromatography (2% MeOH/CHCl3) to give the cyclophane
amide 6 as a white solid (0.47 g, 50%). Found: C, 81.32; H, 5.51; N,
6.38%. C60H48N4O4 requires C, 81.06; H, 5.44; N, 6.30%; Rf (2%
MeOH/CHCl3) 0.35; mp 260 ꢁC; IR (KBr, cmꢀ1) 1634, 1406; dH
(400 MHz, CDCl3) 3.20 (br s, 2H, CH2N), 3.48 (distorted doublet, 6H,
CH2N), 4.50 (br s, 2H, CH2N), 5.34 (distorted doublet, 6H, CH2N),
6.35 (t, 4H, J¼7.2 Hz), 6.59 (s, 4H), 6.73 (s, 2H), 7.14 (d, 8H, J¼9.8 Hz),
7.33 (t, 4H, J¼7.5 Hz), 7.45e7.61 (m, 8H), 7.74 (br s, 2H); dC
(100 MHz, CDCl3) 45.5, 52.1, 52.6, 55.1, 124.3, 125.8, 126.2, 127.1,
128.1,128.5,128.8,129.1,129.7,131.2,132.9,134.8,135.3,137.0,138.4,
143.0, 170.3, 171.3; MS (ES) m/z: 889.3 [MþH]þ.
4.4.6. Cyclophane amide 10. The crude product was purified by
column chromatography (5% MeOH/CHCl3) to give the cyclophane
amide 10 as off-white solid (1.20 g, 70%). Found: C, 82.76; H, 5.35;
N, 5.71. C34H26N2O2 requires C, 82.57; H, 5.30; N, 5.66%; Rf (5%
MeOH/CHCl3) 0.35; mp 260 ꢁC (decomposed); IR (KBr, cmꢀ1
)
1639, 1607, 1487; dH (400 MHz, DMSO-d6) 4.56 (s, 4H, CH2N), 7.44
(t, 4H, J¼8.3 Hz), 7.72 (d, 4H, J¼7.9 Hz), 7.88 (d, 6H, J¼8.2 Hz),
8.04e8.27 (m, 6H), 9.20 (t, 2H, J¼5.5 Hz, NH); MS (ES) m/z: 495.1
[MþH]þ.
4.4.7. Cyclophane sulfonamide 11. The crude product was purified
by column chromatography (5% MeOH/CHCl3) to give the cyclo-
phane amide 11 as off-white solid (1.19 g, 70%). Found: C, 63.86;
H, 4.57; N, 5.79%. C52H44N4O8S4 requires C, 63.65; H, 4.52; N,
5.71%; Rf (5% MeOH/CHCl3) 0.40; mp 236 ꢁC; IR (KBr, cmꢀ1) 1603,
1517, 1478; dH (400 MHz, DMSO-d6) 4.07 (d, 8H, J¼5.8 Hz, CH2N),
7.13 (d, 2H, J¼8.2 Hz), 7.29 (d, 4H, J¼7.8 Hz), 7.46 (d, 3H, J¼8.1 Hz),
7.49e7.57 (m, 6H), 7.61 (d, 5H, J¼7.1 Hz), 7.70 (d, 1H, J¼7.8 Hz),
7.74 (d, 1H, J¼7.9 Hz), 7.77 (s, 2H), 7.81e7.86 (m, 2H), 7.93 (dd, 1H,
J¼1.7 Hz), 7.99 (d, 2H, J¼7.7 Hz), 8.12 (s, 1H), 8.24 (s, 1H), 8.29 (t,
1H, J¼6.3 Hz), 8.51 (ABq, 4H, J¼5.8 Hz, NH); dC (100 MHz, DMSO-
d6) 47.1, 127.5, 129.1, 129.4, 129.8, 130.9, 133.6, 141.8; MS (ES) m/z:
981.2 [MþH]þ.
4.5.4. Cyclophane sulfonamide 7. The crude product was purified
by column chromatography (2% MeOH/CHCl3) to give the cyclo-
phane amide 7 as off-white solid (0.69 g, 75%). Found: C, 60.23; H,
4.65; N, 6.42. C44H40N4O8S4 requires C, 59.98; H, 4.58; N, 6.36%; Rf
(2% MeOH/CHCl3) 0.30; mp 370 ꢁC (decomposed); IR (KBr, cmꢀ1
)
1624, 1449, 1334; dH NMR (400 MHz, DMSO-d6) 3.65 (s, 4H, CH2N),
4.17 (s, 4H, CH2N), 4.37 (s, 8H, CH2N), 7.15e7.18 (m, 5H), 7.24e7.29
(m, 8H), 7.53 (d, 1H, J¼7.8 Hz), 7.60 (d, 2H, J¼7.5 Hz), 7.66 (t, 2H,
J¼7.7 Hz), 7.83 (s, 1H), 7.94 (t, 3H, J¼8.8 Hz), 9.13 (br s, 2H); dC
(100 MHz, DMSO-d6) 45.6, 48.9, 49.3, 51.8, 124.0, 127.3, 128.3, 128.7,
128.9, 129.1, 129.2, 129.3, 129.5, 129.6, 130.1, 130.4, 130.8, 131.3,
132.0, 132.3, 136.8, 138.5, 149.4; MS (ES) m/z: 881.1 [MþH]þ.
4.5. General procedure for the synthesis of tricyclic
cyclophane amides
4.5.5. Cyclophane amide 12. The crude product was purified by
column chromatography (2% MeOH/CHCl3) to give the cyclophane
amide 12 as a white solid (0.56 g, 45%). Found: C, 84.81; H, 5.50; N,
4.76. C84H64N4O4 requires C, 84.54; H, 5.41; N, 4.69%; Rf (2% MeOH/
CHCl3) 0.40; mp 272 ꢁC; IR (KBr, cmꢀ1) 1634, 1597; dH (400 MHz,
CDCl3) 3.80, 3.84 (a pair of doublets, 4H, J¼1.7 Hz, CH2N), 4.62 (q,
8H, J¼14.8, 16.1 Hz, CH2N), 4.83, 4.87 (a pair of doublets, 4H, J¼8.1,
7.9 Hz, CH2N), 6.71 (s, 1H), 6.76 (s, 1H), 6.79e6.86 (m, 4H), 6.96 (t,
1H, J¼7.6 Hz), 7.02 (t, 1H, J¼7.5 Hz), 7.09, 7.11 (two doublets, 8H,
J¼2.2 Hz), 7.14e7.18 (m, 8H), 7.32 (d, 2H, J¼1.3 Hz), 7.39 (d, 6H,
J¼0.9 Hz), 7.42e7.47 (m, 5H), 7.50e7.55 (m, 7H), 8.31 (d, 4H,
J¼7.9 Hz); dC (100 MHz, CDCl3) 49.0, 52.5, 125.8, 125.9, 126.1, 127.0,
127.7, 127.9, 128.2, 129.2, 129.3, 129.4, 134.7, 134.8, 137.1, 137.5, 137.6,
138.2, 140.0, 141.6, 170.7; MS (ES) m/z: 1193.7 [MþH]þ.
A solution of tetraamine (1.05 mmol) in dry dichloromethane
(250 mL) and a solution of the corresponding diacid chloride
(2.10 mmol) in dichloromethane (250 mL) were simultaneously
added dropwise to a well stirred solution of triethylamine (4.2 mmol)
in dry dichloromethane (500 mL) for 6 h. After the addition was
complete, the reaction mixture was stirred for another 24 h. The sol-
vent was removed at reduced pressure and the residue obtained was
then dissolved in chloroform (250 mL), washed with water
(2ꢂ200 mL) to remove triethylammonium chloride, and then dried
over anhydrous sodium sulfate. Removal of the chloroform under re-
duced pressure gave the corresponding cyclophane amide as a crude
material, which was purified by column chromatography (SiO2).
4.5.6. Cyclophane amide 13. The crude product was purified by
column chromatography (2% MeOH/CHCl3) to give the cyclophane
amide 13 as a white solid (0.63 g, 50%). Found: C, 84.82; H, 5.48; N,
4.76. C84H64N4O4 requires C, 84.54; H, 5.41; N, 4.69%; Rf (2% MeOH/
CHCl3) 0.35; mp 282 ꢁC; IR (KBr, cmꢀ1) 1634, 1597; dH (400 MHz,
CDCl3) 3.80, 3.84 (two d, 4H, J¼1.7 Hz, CH2N), 4.62 (ABq, 8H, J¼14.8,
16.1 Hz, CH2N), 4.85 (q, 4H, J¼8.0 Hz, CH2N), 6.71 (s,1H), 6.76 (s,1H),
6.79e6.86 (m, 4H) 6.96 (t, 1H, J¼7.6 Hz), 7.02 (t, 1H, J¼7.5 Hz), 7.09,
7.11 (two d, 8H, J¼2.2 Hz), 7.14e7.18 (m, 8H), 7.32 (d, 2H, J¼1.3 Hz),
7.39 (d, 6H, J¼0.9 Hz), 7.42e7.47 (m, 5H), 7.50e7.55 (m, 7H), 8.31 (d,
4.5.1. Cyclophane amide 4. The crude product was purified by col-
umn chromatography (2% MeOH/CHCl3) to give the cyclophane
amide 4 as a white solid (0.50 g, 65%). Found: C, 78.43; H, 5.51; N,
7.72. C48H40N4O4 requires C, 78.24; H, 5.47; N, 7.60%; Rf (2% MeOH/
CHCl3) 0.45; mp 176 ꢁC; IR (KBr, cmꢀ1) 1639, 406; dH (400 MHz,
CDCl3) 4.10 (d, 8H, J¼14.7 Hz, CH2N), 4.81 (d, 8H, J¼14.7 Hz, CH2N),
7.15 (d, 8H, J¼7.5 Hz), 7.23 (d, 4H, J¼7.5 Hz), 7.63 (ABq, 12H,
J¼7.6 Hz); dC (100 MHz, CDCl3) 45.2, 49.4, 51.0, 53.6, 57.1, 124.8,
125.5,127.1,127.1,127.2,127.8,128.0,128.4,128.9,129.0,129.2,130.0,

9678
P. Rajakumar, R. Padmanabhan / Tetrahedron 67 (2011) 9669e9679
4H, J¼7.9 Hz); dC (100 MHz, CDCl3) 49.0, 52.5, 125.8, 125.9, 126.1,
127.0, 127.7, 127.9, 128.2, 129.2, 129.3, 129.4, 134.7, 134.8, 137.1, 137.5,
137.6, 138.2, 140.0, 141.6, 170.7; MS (ES) m/z: 1193.7 [MþH]þ.
in vitro studies. R.P. thanks Orchid Chemicals & Pharmaceuticals
Ltd. for providing the laboratory and analytical facility.
Supplementary data
4.6. Biological activity
X-ray crystal data for cyclophane amide 5 (Table 1) is available.
Crystallographic data for the structure in this paper have been de-
posited with the Cambridge Crystallographic Data Centre as sup-
plementary publication numbers CCDC 743880 and CCDC 743881.
Copies of the data can be obtained, free of charge, on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [e-mail: depos-
it@ccdc.cam.ac.uk]. Supplementary data associated with this article
can be found in online version, at doi:10.1016/j.tet.2011.10.046.
4.6.1. In vitro anti-inflammatory assay. The HRBC membrane sta-
bilization has been used as
a method to study the anti-
inflammatory activity using prednisolone as standard drug. Blood
was collected from healthy volunteers and the collected blood was
mixed with equal volume of sterilized Alsever’s solution (2% dex-
trose, 0.8% sodium citrate, 0.05% citric acid, and 0.42% sodium
chloride). The blood was centrifuged at 1500 rpm and the packed
cells were washed with isotonic sodium chloride (0.85%, pH 7.2)
and a 10% v/v suspension of the packed cells was made with iso-
tonic sodium chloride. The assay mixture contains the cyclophane
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