Syntheses and properties of dithia-tetrahomodiaza-calix[4]arenes bridged by cystine unit

Article abstract of DOI:10.1002/jhet.5570400302

Dithia-tetrahomodiaza-calix[4]arenes were synthesized by the cyclization reactions of bis(3-(chloromethyl)-2-hydroxyphenyl) sulfide with cystine peptides in moderate yields. Conformational analysis of the macrocycles by using nmr spectroscopy reveled that

Full text of DOI:10.1002/jhet.5570400302

405
Syntheses and Properties of
May-Jun 2003
Dithia-tetrahomodiaza-calix[4]arenes Bridged by Cystine Unit
Kazuaki Ito*, Akane Suzuki, Naoto Ito, Hiroyuki Teraura and Yoshihiro Ohba
Department of Chemistry and Chemical Engineering, Faculty of Engineering,
Yamagata University, Yonezawa 992-8510, Japan
Received December 11, 2002
Dithia-tetrahomodiaza-calix[4]arenes were synthesized by the cyclization reactions of bis(3-(chloro-
methyl)-2-hydroxyphenyl)sulfide with cystine peptides in moderate yields. Conformational analysis of the
macrocycles by using nmr spectroscopy reveled that the cyclophanes adopt a cone-like form as a preferable
conformation and the cystine bridge moiety is incorporated in the cavity. The calixarene analogs can extract
2+
2+
transion metals such as Zn and Cu ions from an aqueous phase into chloroform.
J. Heterocyclic Chem., 40, 405 (2003).
Introduction.
present paper, we report the synthesis of dithia-tetraho-
modiaza- calix[4]arenes in which four methylene bridges
During the last two decades, the large number of pub-
lished studies concerning calixarenes demonstrates a sub-
stantial interest in this class of molecules. Due to consider-
able synthetic effort, many calixarenes, in particular cal-
ixarene derivatives bearing a variety of functional groups
at the small (lower) and/or large (upper) rims have been
synthesized [1,2]. However, only recently a new class cal-
ixarene derivatives was reported in which the methylene
bridges between the phenolic moieties was replaced by
hetero atoms leading to heterocalixarenes [3-6]. These het-
eroatom bridges offer promising alternative to the original
design of this class molecules leading to dramatic changes
of their dynamic and complexation properties. In the
(-CH -) were replaced by two epithio groups (-S-) and two
2
dihomoaza bridges (-CH NRCH -), their structural analy-
2
2
sis and metal extraction ability.
Results and Discussion.
Bis(3-(chloromethyl)-2-hydroxyphenyl)sulfide (5) were
prepared by a chlorination of the corresponding bis(hydrox-
ymethyl) compound (4) using thionyl chloride [7]. Cystine
peptides (3b-3d) were synthesized by a solution phase
synthetic method according to the literature. We carried out
the cyclization reaction of 5a with L-cystine dimethyl ester
(3a) in the presence of sodium carbonate at room tempera-
ture in N,N-dimethyl formamide, and obtained dithia-tetra-

406
K. Ito, A. Suzuki, N. Ito, H. Teraura and Y. Ohba
Vol. 40
homodiaza-calix[4]arene (1a) bridged by cystine unit in 15
% yield (Scheme 1). Similarly, reactions of 5a with cystine
peptides (3b and 3c) afforded the corresponding macro-
cycles (1b and 1c) in 2 and 3 % yields, respectively [8].
Analogous reaction of 5b with 3a also gave 1d in 20 %
yield. When we used cystine peptide 3d in the reaction with
5, macrocycles (2a and 2b) were afforded in 35 and 19 %
yields, respectively (Scheme 2) [9].
The structures of the macrocycles (1 and 2) were
established on the basis of their Fab-mass, nmr, and ir

May-Jun 2003
Syntheses and Properties of Dithia-tetrahomodiaza-calix[4]arenes
407
spectral data, and elemental anaylsis. The assignment of
proton and carbon atoms was obtained by using 2D nmr
experiments. In H-nmr spectra of 1 in deuteriochloroform
bonding not only with a hydroxyl group but also with the
adjacent nitrogen atom [11]. In the ir spectra of 1 in chloro-
form, the OH stretching vibrations appeared in the range of
3330-3380 cm as broad bands. These spectral data indi-
cate the existence of intramolecular hydrogen bonding.
1
at 20 °C, the phenolic OH signals were observed in the
range of δ 9.2-10.5 ppm [10]. Lowering the temperature to
–60 °C slowed down the rate of proton exchange, and two
signals with equal intensity appear (1a: δ 8.50, 10.97 ppm,
1b: δ 9.25, 11.71 ppm, 1c:δ 9.52, 12.00 ppm, 1d: δ 8.50,
10.88 ppm). Considering that a nitrogen atom is a good
proton acceptor, the OH peaks observed at lower magnetic
field are assigned to the OH proton formed by hydrogen
-1
The intramolecular hydrogen bonding in 1 is somewhat
weaker than that of tetrahomodiazacalix[4]arene (δ ca.
OH
-1
1
9 and 11-12 ppm, ν 3270-3290 cm ) [12]. The H- and
C-nmr spectra of 1 show a C symmetry pattern. The
OH
13
2
Corey-Pauling-Koltum model consideration of 1 implied
5
0
-5
-8
250
300
350
wavelength / [nm]
Figure 4. CD Spectra of 1 in chloroform at 20 °C

408
K. Ito, A. Suzuki, N. Ito, H. Teraura and Y. Ohba
Vol. 40
that it adopts a cone conformation because it is difficult to
construct a 1,2-alternate model.
spectra of 1a and 1d in the range of 55 °C to –60 °C in
deuteriochloroform. Lowering the temperature resulting in
The nOe correlations observed for 1a as shown in
Figure 1 strongly suggest that the cystine bridge is located
in the cavity of the cyclophane moiety. This is further
a decrease in the ∆δH H value and in an increase in the
g h
∆δH H values (Table 1). The OH proton was observed as
e
f
two kinds of peaks and shifted down field at low
temperature. These results imply that cooling enhances the
contribution of the twisted form.
supported by the fact that the chemical shift of H (δ 1.34
a
ppm) and H (δ 1.90 ppm) protons of 1a were observed at
b
higher magnetic field compared with analogous compound
We also studied the solvent extraction of various metals
ions (Li , Na , K , Rb , Cs , Zn , Cu ) by 1a from an
aqueous phase to a chloroform phase. Although 1a could
+
+
+
+
+
2+
2+
(2a) (H : 3.22 ppm, H : 3.32 ppm) due to shielding by the
a
b
phenyl rings. Analogously, nOe cross peak were observed
for 1c, between methyl protons of the valine residue and
+
hardly extract alkali metal ions (percent extraction; Li
+
+
+
+
aromatic proton H (Figure 1), implying that the cystine
(5%), Na (9 %), K (2 %), Rb (2 %), Cs (2 %)), the
transition metal ions (percent extraction; Zn (61 %),
Cu (83 %)) were extracted effectively. Considering that
k
2+
peptide bridge is also located in the cavity.
2+
Since it is known that cyclophanes can bind quaternary
ammonium ions, we used α-methylbenzyl trimethyl-
ammonium iodide as a guest, measuring the complexation
calixarene can not extract any metal ions, these results can
be rationalized by assuming that two epithio groups and
dihomoaza bridges of 1a can play an important role in the
extraction of the transition metal ions [13,14].
1
by means of H nmr spectroscopy in deuteriochloroform
solution. However, the chemical shifts of the quaternary
ammonium iodide scarcely changed in the presence of 1. It
may relate that the cystine bridge is located in the cavity.
In conclusion, we have demonstrated the first synthesis
of chiral dithia-tetrahomodiaza-calix[4]arenes from the
cyclization of bis(3-(chloromethyl)-2-hydroxyphenyl)-
sulfide with cystine derivatives. Nmr and circular dichro-
ism spectra of the macrocycles (1) show chiral transmis-
sion from the bridge to the cyclophane moiety. The macro-
Considering that the ∆δ values of the ArCH N methyl-
2
ene protons are expected to be sensitive to the dihedral
angle between the methylene proton and the adjacent
aromatic ring, the different between ∆δH H (0.63 ppm)
e
f
2+
cycle can extract transion metal ions such as Zn and
and ∆δH H (0.18 ppm) for 1a implies that sulfur-bridged
g
h
2+
Cu by solvent extraction method.
phenol dimer moieties adopted a twisted form (Figure 2).
Since the smaller ∆δ values are ascribed to the CH H
g
h
methylene protons, it is reasonable to assume that the
methylene protons are located in an equivalent magnetic
field (conformation A in Figure 3). In contrast, the larger
EXPERIMENTAL
Melting points were measured using a Yanagimoto Micro
1
13
Melting Point Apparatus. H and C nmr spectra were measured
with Varian Mercury 200 and Varian INOVA 500 spectropho-
tometers, using tetramethylsilane as an internal standard. Ir spec-
tra were taken on a Horiba FT-200 spectrophotometer. Fab ms
spectra were measured on JEOL AX-350 spectrometer, using
m-nitrobenzyl alcohol as a matrix. Column chromatography on
silica gel (Kieselgel 60, 63-200 mm, 70-230 mesh, Merck). All
amino acid were used in the L-form. Cystine peptides (3b, 3c, and
3d) and bis(2-hydroxy-3-(hydroxymethyl)phenyl)sulfide (4) were
prepared according to the methods reported in literature [7,8].
∆δ values (CH H ) indicate that the adjacent aromatic ring
e
f
adopts a somewhat standup form (conformation B in
Figure 3). A similar tendency was also observed in 1b
(∆δH H : 1.12 ppm and ∆δH H : 0.90 ppm), 1c (∆δH H :
e
f
g
h
e f
1.24 ppm and ∆δH H : 0.74 ppm), and 1d (∆δH H : 0.61
g
h
e f
ppm and ∆δH H : 0.14 ppm). Based on these considera-
g
h
tions, the sulfur-bridged phenol dimer moieties of 1 are
considered to adopt a twisted structure as shown in Figure
2. The chirality of the L-cystine bridge prefers to form the
left-hand isomer in Figure 2. In other words, the central
chirality of the bridges transfers to the cyclophane moiety.
To prove the existence of chirality in the sulfur-bridged
phenol dimer unit, we measured the circular dichroism
spectra in chloroform at 20 °C. The circular dichroism
spectra of 1 were clearly observed at ca. 300 nm (1a: 305
nm (θ -18900), 1b: 304 nm (θ -66800), 1c: 304 nm
(θ -37300), 1d: 307 nm (θ -29400)) due to the phenol chro-
mophore, supporting the assumption that the dihydroxy
diphenyl sulfide moieties assume a chiral conformation
(Figure 4) [12]. In contrast, the circular dichroism spectral
intensity of 2 was fairly small (2a: 298 nm (θ 6100), 2b:
303 nm (θ -2800)). This indicates that the cystine bridge of
1 efficiently transfers chirality in this system.
Synthesis of Bis(3-(chloromethyl)-2-hydoxyphenyl)sulfide (5).
To a solution of bis(2-hydroxy-3-(hydroxymethyl)phenyl)-
sulfide (4) (7.6 mmol) in dry benzene (45 ml) was added a solu-
tion of thionyl chloride (5.5 ml, 76 mmol) in dry benzene (20 ml)
at room temperature over 1 h. After the addition was complete,
the mixture was stirred at room temperature for 4 h. Removal of
benzene gave 5 as a colorless oil.
1
Compound 5a was obtained as colorless oil. H nmr (deuterio-
chloform): δ 1.23 (18H, s, t-Bu), 4.68 (4H, s, CH ), 6.36 (2H, bs,
2
13
OH), 7.29 (4H, s, Ar-H). C nmr (deuteriochloform): δ 31.1,
42.4, 119.1, 123.8, 128.6, 131.2, 144.5, 151.6. Fab-mass m/z 426
+
(M+H) .
Anal. Calcd. for C H O Cl S C, 61.82; H, 6.60. Found C,
22 28
2
2 2
61.77; H, 6.55.
Compound 5b was obtained as coloress oil. H nmr (deuterio-
chloroform): δ 2.22 (6H, s, Me), 4.65 (4H, s, CH ), 6.40 (bs, 2H,
1
In order to evaluate the temperature dependence of this
2
1
chirality, we measured variable temperature H nmr
OH), 7.10 (2H, d, J=1.5 Hz, Ar-H), 7.12 (2H, d, J=1.5 Hz, Ar-H).

May-Jun 2003
Syntheses and Properties of Dithia-tetrahomodiaza-calix[4]arenes
409
13
d, J=2.0 Hz, H ), 7.77 (2H, d, J=2.0 Hz, H ), 10.51 (4H, bs, OH).
C nmr (deuteriochloform): δ 20.6, 20.9, 27.2, 31.3, 31.4, 34.0,
C nmr (deuteriochloroform): δ 20.4, 41.9, 119.2, 124.2, 131.0,
i
l
+
13
132.4, 134.7, 151.7. Fab-mass m/z 343 (M+H) .
Anal. Calcd. for C H O Cl S C, 55.98; H, 4.70. Found C,
36.8, 52.2, 52.5, 54.1, 57.7, 64.3, 119.5, 121.4, 121.6, 121.9,
16 16
2
2 2
55.79; H,4.80.
127.5, 131.9, 132.9, 134.1, 142.8, 143.1, 154.4, 155.1, 171.5,
-1
172.4. Ir (chloroform) cm : 3330 (ν ), 1749 (ν ), 1684
OH
CO
+
General Procedure for the Preparation of Dithia-tetrahomodiaza-
calix[4]arenes (1).
(amide I), 1506 (amide II). Fab-mass m/z: 1176 (M+H) .
Anal. Calcd. for C H N O S : C, 63.34; H, 7.37; N, 4.77.
62 86
4 10 4
To a suspension of sodium carbonate (159 mg, 1.5 mmol) in
dry N,N-dimethyl formamide (10 ml) were added a solution of 3
(0.25 mmol) in dry N,N-dimethyl formamide (10 ml) and a solu-
tion of 5 (214 mg, 0.5 mmol) in dry N,N-dimethyl formamide
(10 ml) simultaneously at 30 °C over 0.5 h. After the addition
was completed, the mixture was stirred at 30 °C for 10 h.
Removal of N,N-dimethyl formamide under a reduced pressure
below 40 °C gave pale yellow oily residue, which was subjected
to column chromatography on silica gel using hexane:ethyl
acetate 4:1 as an eluent to give 1 as crystals.
Found: C, 63.55; H, 7.21; N, 4.55.
Compound 1d was obtained in 20 % yield mp 253-255 °C. H
nmr (deuteriochloform): δ 1.74 (2H, dd, J=9.0, 12.5 Hz, H ),
1
a
2.24 (12H, s, CH ), 2.26 (2H, d, J=12.5 Hz, H ), 3.60 (2H, d,
3
b
J=12.5 Hz, H ), 3.81 (12H, s, CH ), 3.88 (2H, d, J=9.0 Hz, H ),
e
3
c
4.04 (2H, d, J=13.0 Hz, H ), 4.18 (2H, d, J=14.5 Hz, H ), 4.21
g
h
(2H, d, J=13.5 Hz, H ), 6.80 (2H, s, H ), 6.90 (2H, s, H ), 7.37
f
j
k
(2H, s, H ), 7.44 (2H, s, H ), 9.30 (2H, bs, OH), 9.78 (2H, bs,
l
i
13
OH). C nmr (deuteriochloform): δ 20.2, 32.1, 51.7, 60.3, 60.4,
120.7, 120.9, 122.0, 122.9, 129.1, 129.5, 132.6, 136.2, 136.8,
1
Compound 1a was obtained in 15 % yield mp 140-145 °C. H
nmr (deuteriochloroform): δ 1.15 (18H, s, t-Bu), 1.24 (18H, s,
-1
155.1, 170.1. Ir (chloroform) cm : 3380 (ν ), 1732 (ν ). Fab-
OH
CO
+
mass m/z: 786 (M+H) .
Anal. Calcd. for C H N O S : C, 58.14; H, 5.65. Found: C,
t-Bu), 1.34 (2H, dd, J=10.5, 14.0 Hz, H ), 1.90 (2H, dd, J=2.0,
a
38 44
2 8 4
14.0 Hz, H ), 3.57 (2H, d, J=13.5 Hz, H ), 3.74 (6H, s, CO CH ),
b
e
2
3
58.20; H, 5.42.
3.87 (2H, dd, J=2.0, 10.5 Hz, H ), 3.92 (2H, d, J=13.0 Hz, H ),
c
g
General Procedure for the Preparation of Macrocycles (2).
To a suspension of sodium carbonate (159 mg, 1.5 mmol) in
dry N,N-dimethyl formamide (10 ml) were added a solution of 5
(0.5 mmol) in dry N,N-dimethyl formamide (10 ml) and a solu-
tion of 3d (268 mg, 0.5 mmol) in dry N,N-dimethyl formamide
(10 ml) simultaneously at 30 °C over 1 h. After the addition was
completed, the mixture was stirred at 30 °C for 10 h. Removal of
N,N-dimethyl formamide under a reduced pressure below 40 °C
gave pale yellow oily residue, which was subjected to column
chromatography on silica gel using ethyl acetate as an eluent to
give 2 as crystals.
4.10 (2H, d, J=13.0 Hz, H ), 4.19 (2H, d, J=13.5 Hz, H ), 6.91
h
f
(2H, d, J=2.5 Hz, H ), 7.05 (2H, d, J=2.5 Hz, H ), 7.43 (2H, d,
j
k
13
J=2.5 Hz, H ), 7.65 (2H, d, J=2.5 Hz, H ), 9.20 (4H, bs, OH).
C
l
i
nmr (deuteriochloroform): δ 31.4, 31.5, 34.0, 41.8, 51.6, 56.4,
59.4, 59.9, 120.8, 121.0, 121.6, 122.5, 128.8, 129.4, 132.2, 133.3,
-1
142.8, 143.0, 154.2, 155.1, 169.9. Ir (chloroform) cm : 3380
+
(ν ), 1734 (ν ). Fab-mass m/z: 978 (M+H) .
OH
CO
Anal. Calcd. for C H N O S : C, 63.90; H, 7.01; N, 2.87.
52 68
2 8 4
Found: C, 64.10; H, 6.89; N, 2.91.
1
Compound 1b was obtained in 2 % yield mp 190-193 °C. H
nmr (deuteriochloroform): δ 1.27 (18H, s, t-Bu), 1.33 (18H, s,
t-Bu), 2.69 (2H, dd, J=1.5, 11.5 Hz, CHHPh), 2.95 (2H, dd,
1
Compound 2a was obtained in 35 % yield mp 146-148 °C. H
nmr (deuteriochloform): δ 1.28 (18H, s, t-Bu), 1.78 (4H, m, H
g
J=9.5, 14.5 Hz, H ), 3.25 (2H, dd, J=11.0, 11.5 Hz, CHHPh),
a
and H ), 1.97 (2H, m, H ), 2.25 (2H, m, H ), 2.33 (2H, m, H ),
h
f
e
j
3.28 (2H, dd, J=4.0, 14.5 Hz, H ), 3.33 (2H, dd, J=1.5, 11.0 Hz,
b
2.94 (2H, m, H ), 3.19 (2H, m, H ), 3.22 (2H, dd, J=5.0, 13.5 Hz,
i
d
H ), 3.40 (2H, d, J=13.0 Hz, H ), 3.54 (2H, d, J=14.5 Hz, H ),
d
h
f
H ), 3.32 (2H, dd, J=6.5, 13.5 Hz, H ), 3.35 (2H, bs, H ), 3.73
a
b
k
3.60 (6H, s, CO CH ), 4.29 (2H, d, J=13.0 Hz, H ), 4.64 (2H,
2
3
g
(6H, s, CO CH ), 4.33 (2H, d, J=13.5 Hz, H ), 4.83 (2H, ddd,
2
3
l
ddd, J=4.0, 5.0, 9.0 Hz, H ), 4.66 (2H, d, J=14.5 Hz, H ), 6.83-
c
e
J=5.0, 6.5, 6.5 Hz, H ), 7.04 (2H, bs, H ), 7.40 (2H, bs, H ), 7.92
c
m
n
6.87 (6H, m, Ph-H), 7.20 (2H, d, J=2.0 Hz, H ), 7.63 (2H, d,
k
13
(2H, d, J=6.5 Hz, NH). C nmr (deuteriochloform): δ 23.3, 30.1,
J=2.0 Hz, H ), 7.81 (2H, d, J=2.0 Hz, H ), 10.50 (4H, bs, OH).
i
l
31.4, 39.6, 51.6, 52.7, 53.7, 67.7, 119.8, 123.2, 127.8, 131.1,
13
C nmr (deuteriochloform): δ 27.5, 31.4, 31.5, 34.0, 34.1, 39.5,
-1
142.9, 153.4, 170.8, 174.0. Ir (chloroform) cm : 3395 (ν ),
OH
52.4, 52.7, 55.0, 56.6, 63.0, 119.4, 121.0, 121.6, 121.8, 126.2,
1745 (ν ), 1668 (amide I), 1508 (amide II). Fab-mass m/z: 817
CO
127.8, 128.2, 129.4, 130.4, 133.3, 134.8, 137.9, 143.0, 154.4,
+
(M+H) .
-1
155.1, 170.5, 170.8. Ir (chloroform) cm : 3330 (ν ), 1749
OH
Anal. Calcd. for C H N O S : C, 58.80; H, 6.91. Found C,
40 56
4 8 3
(ν ), 1684 (amide I), 1506 (amide II). Fab-mass m/z: 1272
CO
(M+H) .
58.90; H, 6.70.
Compound 2b was obtained in 19 % yield mp 128-132 °C.
+
Anal. Calcd. for C H N O S : C, 66.11; H, 6.82; N, 4.41.
1
70 86
4
10
4
H nmr (deuteriochloform): δ 1.79 (4H, m, H and H ), 1.99
g h
Found: C, 65.98; H, 6.91; N, 4.22.
Compound 1c was obtained in 3 % yield mp 130-132 °C. H
(2H, m, H ), 2.22 (6H, s, 6H), 2.25 (2H, m, H ), 2.33 (2H, m,
f
e
1
H ), 2.93 (2H, m, H ), 3.19 (2H, m, H ), 3.23 (2H, dd, J=5.0,
j
i
d
nmr (deuteriochloform): δ 0.74 (6H, d, J=7.0 Hz, CH ), 1.06
14.0 Hz, H ), 3.31 (2H, bs, H ), 3.33 (2H, dd, J=6.5, 14.0 Hz,
3
a
k
(6H, d, J=7.0 Hz, CH ), 1.25 (18H, s, t-Bu), 1.27 (18H, s, t-Bu),
H ), 3.73 (6H, s, CO CH ), 4.29 (2H, d, J=13.5 Hz, H ), 4.81
3
b
2
3
l
2.50 (2H, m, CH(CH ) ), 2.77 (2H, d, J=10.0 Hz, H ), 2.81 (2H,
(2H, ddd, J=5.0, 6.5, 6.5 Hz, H ), 6.86 (2H, bs, H ), 7.22 (2H,
3 2
d
c
m
13
dd, J=12.0, 14.0 Hz, H ), 3.31 (2H, dd, J=3.5, 14.0 Hz, H ), 3.50
bs, H ), 7.94 (2H, bs, NH). C nmr (deuteriochloform): δ 20.3,
a
b
n
(2H, d, J=12.0 Hz, H ), 3.71 (2H, d, J=14.5 Hz, H ), 3.76 (6H, s,
23.3, 30.0, 39.8, 51.7, 52.7, 53.6, 57.3, 67.6, 120.1, 123.7,
129.3, 131.7, 134.7, 153.7, 170.8, 174.0. Ir (chloroform) cm :
g
e
-1
CO CH ), 4.24 (2H, d, J=12.0 Hz, H ), 4.70 (2H, ddd, J=3.5, 3.5,
2
3
h
12.0 Hz, H ), 4.95 (2H, d, J=14.5 Hz, H ), 6.93 (2H, bs, NH),
3396 (ν ), 1747 (ν ), 1670 (amide I), 1508 (amide II). Fab-
mass m/z: 733 (M+H) .
c
f
OH
CO
+
7.02 (2H, d, J=2.0 Hz, H ), 7.06 (2H, d, J=2.0 Hz, H ), 7.61 (2H,
j
k

410
K. Ito, A. Suzuki, N. Ito, H. Teraura and Y. Ohba
Vol. 40
[4] K. Kumagai, H. Hasegawa, S. Miyanari, Y. Sugawara,
Y. Sato, T. Hori, S. Ueda, H. Kamiyama, and S. Miyano, Tetrahedron
Lett., 38, 3971 (1997).
Anal. Calcd. for C H N O S : C, 55.72; H, 6.05. Found C,
55.65; H, 5.99.
34 44
4 8 3
Solent Extraction.
[5] H. Takemura, J. Incl. Phenom., 42, 169 (2002).
[6] J. L. Sessler, W.-S. Cho, V. Lynch, and V. Kral., Chem., Eur.
J., 8, 1134 (2002).
[7] Y. Ohba, K. Moriya, T. Sone, Bull. Chem. Soc. Jpn., 64, 576
(1991).
-4
To a 30 ml vial tube were pipetted a solution of 1a (5 x 10
M) in chloroform (10 ml) and aqueous solution (10 ml)
containing a metal ion (1 x 10 M), pH buffer (5 x 10
-4
-2
M
Tris-HCl at pH 8.0). The mixture was shaken for 30 min. The
total concentration of metal species remaining in aqueous
phase was measured by Zeeman atomic absorption spectro-
meter.
[8] H. Huang, L.-J. Mu, J.-P. Cheng, J.-M. Lu and X.-B. Hu,
Synth. Commun., 28, 4639 (1998).
[9] Reactions of 5 with benzyl amine and L-amino acid methyl
ester instead of cystine derivatives under several reaction conditions did
not give any product except polymeric materials.
1
[10] The phenolic OH protons of 2 in the H NMR spectra are too
broad to observe the signal even at –60 °C in deuteriochloroform.
[11] K. Ito, Y. Ohba and T. Sone, J. Heterocyclic Chem, 35, 1317
(1998).
[12] K. Ito, T Ohta, Y. Ohba and T. Sone, J. Heterocyclic Chem.,
37, 79 (2000).
REFERENCES AND NOTES
[1] C. D. Gutsche, “Calixarene,” Royal Society of Chemistry,
London, 1989.
[2] C. D. Gutsche, “Calixarene Revisited,” Royal Society of
Chemistry, London, 1998.
[13] S.-K. Chang and I. Cho, J. Chem. Soc., Perkin Trans 1, 211
(1986).
[3] S. Ibach, V. Prautzsch, F. Vogtle, C. Chartrouv and J. Gloe,
Acc. Chem. Res., 32, 729 (1999).
[14] N. Iki, N. Morohashi, F. Narumi, and S. Miyano, Bull. Chem.
Soc. Jpn., 71, 1597 (1998).