Tunable threading/dethreading efficiency of the pseudorotaxane by ether chain length

Article abstract of DOI:10.1016/j.tetlet.2008.06.015

A series of axles containing the tetraethyl ester calix[4]arene derivative unit and 1,5-dioxynaphthalene (DNP) unit, with different lengths of ether chains, have been synthesized. Complexation of the axles and the cyclobis(paraquat-p-phenylene) (CBPQT⁴⁺) has been investigated by UV-vis and ¹H NMR spectra. The effect of the length of ether chain on the threading/dethreading processes has also been demonstrated, which indicated that the efficiency of threading/dethreading process decreases with the extension of ether chain.

Full text of DOI:10.1016/j.tetlet.2008.06.015

Tetrahedron Letters 49 (2008) 4857–4861
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Tunable threading/dethreading efficiency of the pseudorotaxane
by ether chain length
a
Junbo Li a,b, Weidong Zhou a,b, Yuliang Li a, , Huibiao Liu , Canbin Ouyang a,b, Xiaodong Yin a,b
,
*
Haiyan Zheng a,b, Zicheng Zuo a,b
a Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China
b Graduate School of Chinese Academy of Sciences, Beijing 100190, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of axles containing the tetraethyl ester calix[4]arene derivative unit and 1,5-dioxynaphthalene
(DNP) unit, with different lengths of ether chains, have been synthesized. Complexation of the axles
and the cyclobis(paraquat-p-phenylene) (CBPQT4+) has been investigated by UV–vis and 1H NMR spectra.
The effect of the length of ether chain on the threading/dethreading processes has also been demon-
strated, which indicated that the efficiency of threading/dethreading process decreases with the exten-
sion of ether chain.
Received 17 March 2008
Revised 13 May 2008
Accepted 3 June 2008
Available online 6 June 2008
Keywords:
Molecular machine
Pseudorotaxane
Ó 2008 Elsevier Ltd. All rights reserved.
Cyclobis(paraquat-p-phenylene)
Threading/dethreading
Various molecular-level machines such as rotaxanes and caten-
anes have been reported over the last decade.1 The common fea-
ture of these machines is the reversible switching between two
or more states according to a given stimulus.2 Pseudorotaxanes
have been proven to be highly useful precursors for the construc-
tion of the effective artificial molecular-level machines.3 Therefore,
the design and preparation of pseudorotaxanes with this feature
are necessary for the construction and development of artificial
molecular-level machines.4 This is because the threading/deth-
reading processes of the pseudorotaxanes can be conveniently
and reversibly controlled by external stimuli such as light,5 pH,6
electricity,7 etc.
Pseudorotaxanes created from the electron deficient tetracat-
ionic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT4+) and
electron-rich 1,5-dialkoxynaphthalene units have arguably become
one of the most important building blocks for the synthesis of func-
tional supramolecular systems with near-binary redox-controllable
recognition properties.8 The reduction of the CBPQT4+ unit can
induce the expulsion of the electron-rich 1,5-dialkoxynaphthalene
from the cavity. Meanwhile, other stimuli such as the ions,9 tem-
perature10 and pH11 induced dethreading of the CBPQT4+ ring had
also been investigated widely. We designed and synthesized an axle
which consists of a tetraethyl ester calix[4]arene derivative unit
and a 1,5-dioxynaphthalene (DNP) unit. The tetraethyl ester
calix[4]arene unit is a ligand for alkali metal ions and the DNP unit
can complex with the CBPQT4+ ring.12 The designed axle is able to
act both as host toward alkali metal ions and as guest toward the
CBPQT4+ ring. The [2]pseudorotaxane can be assembled from the
complexation of the axle and the CBPQT4+ ring (Scheme 1). Upon
the addition of K+ ions, the tetraethyl ester calix[4]arene complexed
with the K+ ions, which consequently induced the dethreading of
the CBPQT4+ ring due to the electrostatic repulsion.9 18-crown-6
is a good acceptor for K+ ions; and the binding constant of 18-
crown-6 with K+ ions is more than ten times larger than the tetra-
ethyl ester calix[4]arene with K+ ions.13 The addition of excess of
18-crown-6 can capture the K+ ions coordinated with the calix[4]-
arene, which induces the CBPQT4+ ring threading again. Further-
more, in order to suitably design molecular shuttles or molecular
switches in the future with this system, a series of axles with differ-
ent lengths of ether chain between the calix[4]arene derivative and
1,5-dioxynaphthalene have been synthesized and the K+ ions in-
duced dethreading processes have also been investigated.
* Corresponding author. Tel.: +86 10 62588934; fax: +86 10 82616576.
E-mail address: ylli@iccas.ac.cn (Y. Li).
Scheme 1. The threading/dethreading process of the pseudorotaxane.
0040-4039/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2008.06.015

4858
J. Li et al. / Tetrahedron Letters 49 (2008) 4857–4861
Scheme 2. Synthetic route of the CN1, CN2 and CN3.
The tetracationic cyclophane (CBPQT4+
)
was synthesized
field from 8.19 ppm to 7.73 ppm and downfield from 7.56 ppm to
according to the literatures.14 The synthetic routes employed in
the synthesis of CN1, CN2 and CN3 are summarized in Scheme
2.14 The mono-THP protected 1,5-dioxynaphthanlene 2 reacted
with the tosylated ether chain in the presence of K2CO3 and 18-
crown-6 in CH3CN. The crude product was directly deprotected
to afford 3 in 70% yield. Compound 3 reacted with bromoethanol
in DMF to give 4, which was tosylated subsequently to afford 5.
The synthesis of axle CN1 was achieved by the reaction between
Calix–COOH and compound 5 in 83% yield. The syntheses of the
axles CN2 and CN3 were similar to that of the CN1.
7.87 ppm, respectively. These observations suggest strongly that
the plane of the DNP unit in CN1 is parallel and perpendicular,
respectively, with the bipyridinium and the paraphenylene aro-
matic rings present in CBPQT4+ 16
shifted downfield: He
d = +0.03 ppm), Hk (
.
The signals of methylene protons
d = +0.16 ppm), Hi d = +0.03 ppm), Hj
Dd = +0.11 ppm). Furthermore, both protons
(D
(D
(D
in CBPQT4+ and CN1 broadened, indicating the [2]pseudorotaxane
and free species were in fast exchange on the 1H NMR timescale.
Immediately upon the addition of 5 equiv KPF6 to the NMR tube,
the signals of the phenyl protons Hd shifted downfield from
6.95–7.07 ppm to 7.36–7.40 ppm, indicating K+ ions complexed
with the calix[4]arene derivative.10 Moreover, the signals of pro-
Mixing equimolar proportions of CN1 and CBPQT4+ in CH3CN re-
sulted instantaneously in a deep purple color and the absorption
spectra of the mixture showed a charge transfer (CT) band at
523 nm, indicating the formation of the [2]pseudorotaxane
CN1ꢀCBPQT4+. Upon the addition of 5 equiv KPF6 to the solution
of [2]pseudorotaxane in CH3CN, the purple color faded. As shown
in the UV–vis absorption spectrum (Fig. 1a), the CT band absor-
bance at 523 nm decreased intensely. The absorbance value was
reduced from 0.2 to 0.02, indicating the CBPQT4+ ring dethreading
from the CN1. When 10 equiv 18-crown-6 was added to the solu-
tion, the original purple color was recovered and the CT band
absorbance at 523 nm was regenerated. Meanwhile, the CT band
absorbance value was nearly the same as the original absorbance
value, indicating that 18-crown-6 captures the K+ ions from tetra-
ethyl ester calix[4]arene thoroughly. Thus, the [2]pseudorotaxane
CN1ꢀCBPQT4+ was formed again. Although the similar K+/18-
crown-6 induced threading/dethreading process can be clearly ob-
tained (Fig. 1b and c) in the pseudorotaxanes CN2ꢀCBPQT4+ and
CN3ꢀCBPQT4+, we can also conclude some differences: (1) the CT
band absorbance values of the pseudorotaxanes increase from
CN1ꢀCBPQT4+ to CN3ꢀCBPQT4+, indicating the binding constants, be-
tween the axles and CBPQT4+ ring, increase with the extension of
the ether chain; (2) after addition of 5 equiv KPF6, the CT band
absorbance values increase from CN1ꢀCBPQT4+ to CN3ꢀCBPQT4+ yet.
The 1H NMR spectra also depicted this threading/dethreading
process. Figure 2a and b shows the partial 1H NMR spectra of the
CN1 and the CBPQT4+ ring in CD3CN at 25 °C, respectively. After
mixing equimolar amounts of CN1 and CBPQT4+ in CD3CN, the 1H
NMR spectra (Fig. 2c) showed significant changes. The protons
associated with the DNP unit were appreciably shielded compared
to their free analogues, indicating the encircling of the DNP moiety
by the CBPQT4+ ring.15 The signals for protons Hb and Hc shifted up-
field. At the same time, the signals for these protons broadened
with some overlaps with those of protons Hd (see Supplementary
data, Fig. S13). In addition, of the protons associated with the
tons Hb and H shifted downfield from 7.74 ppm to 8.06 ppm and
c
upfield from 7.83 ppm to 7.62 ppm, respectively, indicating the
cyclophane CBPQT4+ dethreaded from the axle CN1. Furthermore,
the signals for the cyclophane CBPQT4+ became less broad, provid-
ing further evidence for the disrupting of the pseudorotaxane
CN1ꢀCBPQT4+ 17
.
When 10 equiv 18-crown-6 was added to the
NMR tube, the 1H NMR spectrum (Fig. 2d) recovered to Fig. 2c,
indicating the K+ ions were captured by the 18-crown-6, and the
cyclophane CBPQT4+ threaded again.
The complexation of axle with the host CBPQT4+ was monitored
by measuring the absorbance of the visible CT band that developed
upon the mixing of the two components. To determine the binding
constants, the 0.1 mM axles (in CH3CN) and 0.2 mM axles (with
5 equiv KPF6, in CH3CN) were spectrophotometrically titrated with
CBPQT4+ (0.01 M, in CH3CN), respectively. The binding constants
were obtained by computer fitting of the experimental data points
to the following equation:18
b½Sꢁ
1
½Sꢁ
¼
A
þ
½R0ꢁK
D
eRS ½R0ꢁ
DeRS
D
In which
measured at a host concentration [S] and a guest concentration
[R0], b is the optical path length,
eRS is the molar absorptivity of
DA is the absorbance of the charge-transfer complex
D
the charge-transfer complex, and K is the equilibrium constant
for the formation of the complex. The experimental data points
were consistent with 1:1 stoichiometry for all the complexes.
The binding constants are summarized in Table 1.
Data from Table 1 showed that the binding constants (K) of the
pseudorotaxanes increased from CN1ꢀCBPQT4+ (518 Mꢂ1
) to
CN3ꢀCBPQT4+ (10040 Mꢂ1). Meanwhile, K1/K2 signified the K+
ions-induced dethreading efficiency of the pseudorotaxanes, which
reduced from 24.1 to 8.5, indicating that the dethreading efficiency
decreased from CN1ꢀCBPQT4+ to CN3ꢀCBPQT4+. The K2b/K2a value
(6.4) is larger than K1b/K1a (4.4), indicating that the electrostatic
repulsion effect between the K+ ions and CBPQT4+ in CN1ꢀCBPQT4+
CBPQT4+ ring, the chemical shifts for protons H and Hd were al-
a
most identical, whereas those of the protons Hb and H shifted up-
c

J. Li et al. / Tetrahedron Letters 49 (2008) 4857–4861
4859
Figure 1. UV–vis spectra showing the CT bands of the pseudorotaxane (a) CN1ꢀCBPQT4+ (1 ꢃ 10ꢂ3 M, CH3CN), (b) CN2ꢀCBPQT4+ (5 ꢃ 10ꢂ4 M, CH3CN), (c) CN3ꢀCBPQT4+
(5 ꢃ 10ꢂ4 M, CH3CN) (black); upon the addition of 5 equiv KPF6 (green); upon the addition of 10 equiv 18-crown-6 (magenta).
Table 1
A comparison of K (Mꢂ1) for [2]pesudorotaxanes in CH3CN solution
a
b
c
K1(without K+ ions)
K2(with K+ ions)
K1/K2
518
21 19
24.1
7
2276 74
137 33
16.6
10040 150
1186 78
8.5
(a) CN1; (b) CN2; (c) CN3.
is stronger than that in CN2ꢀCBPQT4+. Meanwhile, K2c/K2b (8.6) is
larger than K1c/K1b (4.4), indicating the electrostatic repulsion ef-
fect between the K+ ions and CBPQT4+ in CN2ꢀCBPQT4+ is stronger
than that in CN3CBPQT4+. So the electrostatic repulsion effect is re-
duced with the extension of ether chain. In other words, with the
extension of ether chain, the binding constants (K) increase
whereas the K+ ions-induced dethreading efficiency decreases.
The reasons are probably as follows: (a) The extended ether chain
increases the [C–Hꢀ ꢀ ꢀO] hydrogen bond interaction site between
the ether chain and the acidic
a
-bipyridinium hydrogen atom;19
(b) the steric hindrance effect between the calix[4]arene and the
CBPQT4+ ring is reduced with the increasing distance between
them; (c) the electrostatic repulsion effect between the K+ ions
and CBPQT4+ ring decreases with the extension of ether chain.
In conclusion, we have demonstrated a novel threading/deth-
reading process which can be controlled by 18-crown-6/K+. Inter-
estingly, the efficiency of the threading/dethreading process is
Figure 2. Partial 1H NMR spectra (400 MHz, 298 K, CD3CN) of (a) CN1 (2 ꢃ 10ꢂ3 M);
(b) CBPQT4+ (2 ꢃ 10ꢂ3 M); (c) CN1ꢀCBPQT4+ (2 ꢃ 10ꢂ3 M); (d) CN1ꢀCBPQT4+ + 5
equiv KPF6; (e) CN1ꢀCBPQT4+ + 5 equiv KPF6 + 10 equiv 18-crown-6.

4860
J. Li et al. / Tetrahedron Letters 49 (2008) 4857–4861
Schwing-Weill, M. J.; Seward, E. M. J. Am. Chem. Soc. 1989, 111, 8681; binding
constant of 18-crown-6 with K+ in acetonitrile at 298 K is 105.7, see: (b) Gokel,
G. W.; Leevy, W. M.; Weber, M. E. Chem. Rev. 2004, 104, 2723.
able to be tuned by extending the ether chain between the calix[4]-
arene and 1,5-dioxynapathalene. Further work in our laboratory
will focus on the application of this system to suitably design
molecular shuttles and other molecular switches.
14. (a) Asakawa, M.; Dehaen, W.; L’abbé, G.; Menzer, S.; Nouwen, J.; Rayo, F. M.;
Stoddart, J. F.; Williams, D. J. J. Org. Chem. 1996, 61, 9591; (b) Capobianchi, S.;
Doddi, G.; Ercolani, G.; Keyes, J. W.; Mencarelli, P. J. Org. Chem. 1997, 62, 7051;
(c) The synthetic routes are as follows: Compound 3: 5-(Tetrahydro-2H-pyran-
Acknowledgments
2-yloxy)naphthalene-1-ol
2
(800 mg, 3.28 mmol), 2-(20-(200-Ethoxyeth-
oxy)ethoxy)ethyl 4-methyl benzenesulfonate (1.08 g, 3.28 mmol) and K2CO3
(543 mg, 3.93 mmol) were added to the DMF (20 mL). The solution was heated
at 80 °C for 4 h. After the evaporation of the solvent, CH2Cl2 (50 mL) were
added. The solution was washed with water (3 ꢃ 20 mL). Evaporation of the
solvent gave a crude residue which was dissolved in CH2Cl2/CH3OH (1:1,
20 mL). Then a catalytic amount of p-toluenesulfonic acid was added. The
mixture was stirred at room temperature for 12 h. The solvent was evaporated
and the crude product was chromatographed to give 3 (734 mg, 70%) as a pale
yellow oil. 1H NMR (300 MHz, CDCl3): d 7.85 (d, J = 8.5 Hz, 1H), 7.76 (d,
J = 8.5 Hz, 1H), 7.34 (t, J = 7.8 Hz, 1H), 6.86–6.80 (m, 2H), 5.68 (s, 1H), 4.28 (t,
J = 5 Hz, 2H), 3.98 (t, J = 5 Hz, 2H), 3.85–3.79 (m, 2H), 3.73–3.66 (m, 4H), 3.61–
3.58 (m, 2H), 3.52 (q, J = 7.0 Hz, 2H), 1.20 (t, J = 7.0 Hz, 3H). 13C NMR (150 MHz,
CDCl3): d 154.5, 151.5, 128.1, 125.5, 125.2, 125.1, 114.7, 114.1, 109.5, 105.5,
71.1, 70.8, 69.9, 67.9, 66.8, 15.2. EI-MS: m/z calcd for C18H24O5, 320. Found 320.
Anal. Calcd for C18H24O5: C, 67.48; H, 7.55. Found: C, 67.42; H, 7.57. Compound
This work was supported by the National Nature Science Foun-
dation of China (20531060 and 20571078) and the National Basic
Research 973 Program of China.
Supplementary data
General methods, determination of binding constants, the origi-
nal 1H NMR, 13C NMR, ESI, and TOF spectra of all new compounds.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tetlet.2008.06.015.
4: To
a
solution of compound
3 (700 mg, 2.18 mmol) in DMF (10 mL),
bromoethanol (186.4
l
L, 2.6 mmol) and K2CO3 (603 mg, 4.36 mmol) was
References and notes
added. The solution was heated at 80 °C for 12 h. The solvent was
evaporated and CH2Cl2 (50 mL) was added. The solution was washed with
water (3 ꢃ 10 mL) and then dried over anhydrous MgSO4. The crude product
was chromatographed to give 4 (500 mg, 63%) as a pale yellow oil. 1H NMR
(300 MHz, CDCl3): d 7.90–7.83 (m, 2H), 7.38–7.32 (m, 2H), 6.85 (d, J = 7.6 Hz,
2H), 4.30–4.21 (m, 4H), 4.10–4.06 (m, 2H), 4.00–3.97 (m, 2H), 3.82–3.77 (m,
2H), 3.73–3.60 (m, 4H), 3.60–3.56 (m, 2H), 3.52 (q, J = 7.0 Hz, 2H), 1.20 (t,
J = 7.0 Hz, 3H). 13C NMR (150 MHz, CDCl3): d 154.4, 154.1, 126.8, 126.6, 125.2,
125.0, 114.9, 114.2, 105.8, 105.7, 71.0, 70.7, 69.8, 69.6, 67.9, 66.6, 61.6, 15.1. EI-
MS m/z calcd for C20H28O6, 364. Found 364. Anal. Calcd for C20H28O6: C, 65.91;
1. For the recent review: (a) Kay, E. R.; Leigh, D. A.; Zerbetto, F. Angew. Chem., Int.
Ed. 2007, 46, 72; (b) Tian, H.; Wang, Q.-C. Chem. Soc. Rev. 2006, 35, 361; (c) Kim,
K. Chem. Soc. Rev. 2002, 31, 96.
2. (a) Badjic, J. D.; Balzani, V.; Credi, A.; Silvi, S.; Stoddart, J. F. Science 2004,
303, 1845; (b) Zhou, W.-D.; Li, J.-B.; He, X.-R.; Li, C.-H.; Lv, J.; Li, Y.-L.; Wang,
S.; Liu, H.-B.; Zhu, D.-B. Chem.-Eur. J. 2008, 14, 754; (c) Zhou, W. -D.; Chen,
D.-G.; Li, J.-B.; Xu, J.-L.; Lv, J.; Liu, H.-B.; Li, Y.-L. Org. Lett. 2007, 9, 3929; (d)
Li, Y.-J.; Li, H.; Li, Y.-L.; Liu, H.-B. Org. Lett. 2005, 7, 4835; (e) Saha, S.; Flood,
A. H.; Stoddart, J. F.; Impellizzeri, S.; Silvi, S.; Venturi, M.; Credi, A. J. Am.
Chem. Soc. 2007, 129, 12159; (f) Qu, D.-H.; Wang, Q.-C.; Ma, X.; Tian, H.
Chem.-Eur. J. 2005, 11, 5929; (g) Wang, Q.-C.; Qu, D.-H.; Ren, J.; Chen, K.-C.;
Tian, H. Angew. Chem., Int. Ed. 2004, 43, 2661; (h) Saha, S.; Flood, A. H.;
Stoddart, J. F.; Impellizzeri, S.; Silvi, S.; Venturi, M.; Credi, A. J. Am. Chem. Soc.
2007, 129, 12159.
3. (a) Silvi, S.; Arduini, A.; Pochini, A.; Secchi, A.; Tomasulo, M.; Raymo, F. M.;
Baroncini, M.; Credi, A. J. Am. Chem. Soc. 2007, 129, 13378; (b) Vella, S. J.;
Tiburcio, J.; Gauld, J. W.; Loeb, S. J. Org. Lett. 2006, 8, 3421; (c) Chang, K. J.; An, Y.
J.; Uh, H.; Jeong, K. S. J. Org. Chem. 2004, 69, 6556; (d) Balzani, V.; Credi, A.; Marc
hioni, F.; Stoddart, J. F. Chem. Commun. 2001, 1860; (e) Jeong, K. S.; Chang, K. J.;
An, Y. J. Chem. Commun. 2003, 1450.
4. (a) Ashton, P. R.; Balzani, V.; Kocian, O.; Prodi, L.; Spencer, N.; Stoddart, J. F. J.
Am. Chem. Soc. 1998, 120, 11190; (b) Kaiser, G.; Jarrosson, T.; Otto, S.; Ng, Y.;
Bond, A. D.; Sanders, J. K. M. Angew. Chem., Int. Ed. 2004, 43, 1959; (c) Miljanic´,
O. Š.; Dichtel, W. R.; Mortezaei, S.; Stoddart, J. F. Org. Lett. 2006, 8, 4835; (d)
Nguyen, T. D.; Leung, K. C. F.; Liong, M.; Pentecost, C. D.; Stoddart, J. F.; Zink, J. I.
Org. Lett. 2006, 8, 3363; (e) Bunker, B. C.; Huber, D. L.; Kushmerick, J. G.;
Dunbar, T.; Kelly, M.; Matzke, C.; Cao, J. G.; Jeppsen, J. O.; Perkins, J.; Flood, A.
H.; Stoddart, J. F. Langmuir 2007, 23, 31.
5. (a) Silvi, S.; Arduini, A.; Pochini, A.; Secchi, A.; Tomasulo, M.; Raymo, F. M.;
Baroncini, M.; Credi, A. J. Am. Chem. Soc. 2007, 129, 13378; (b) Jeong, K.-S.;
Chang, K.-J.; An, Y.-J. Chem. Commun. 2003, 1450; (c) Chang, K.-J.; An, Y.-J.; Uh,
H.; Jeong, K.-S. J. Org. Chem. 2004, 69, 6556.
6. (a) Rogez, G.; Ribera, B. F.; Credi, A.; Ballardini, R.; Gandolfi, M. T.; Balzani, V.; Li,
Y.; Northrop, B. H.; Stoddart, J. F. J. Am. Chem. Soc. 2007, 129, 4633; (b) Huang,
F.; Switek, K. A.; Gibson, H. W. Chem. Commun. 2005, 3655; (c) Liu, Y.; Ke, C.-F.;
Zhang, H.-Y.; Wu, W.-J.; Shi, J. J. Org. Chem. 2007, 72, 280; (d) Ooya, T.; Inoue, D.;
Choi, H. S.; Kobayashi, Y.; Loethen, S.; Thompson, D. H.; Ko, Y. H.; Kim, K.; Yui,
N. Org. Lett. 2006, 8, 3159.
7. (a) Gorodets, B.; Branda, N. R. Tetrahedron Lett. 2005, 46, 6761; (b)
Braunschweig, A. B.; Northrop, B. H.; Stoddart, J. F. J. Mater. Chem. 2006, 16,
32; (c) Balzani, V.; Becher, O. J.; Credi, A.; Nielsen, M. B.; Raymo, F. M.; Stoddart,
J. F.; Talarico, A. M.; Venturi, M. J. Org. Chem. 2000, 65, 1947.
8. Anelli, P. L.; Ashton, P. R.; Ballardini, R.; Balzani, V.; Delgado, M.; Gandolfi, M. T.;
Goodnow, T. T.; Kaifer, A. E.; Philp, D.; Pietraszkiewicz, M.; Prodi, L.;
Reddington, M. V.; Slawin, M. V.; Spencer, A. M. Z.; Stoddart, J. F.; Vicent, C.;
Williams, D. J. J. Am. Chem. Soc. 1992, 114, 193.
9. Asakawa, M.; Iqbal, S.; Stoddart, J. F.; Tinker, N. D. Angew. Chem., Int. Ed. 1996,
35, 976.
H, 7.74. Found: C, 65.87; H, 7.70. Compound 5: Compound
3 (930 mg,
2.90 mmol), 2-(20-chloroethoxy)ethanol (434 mg, 3.48 mmol), K2CO3 (802 mg,
5.8 mmol) were allowed to react in the same way as described for 4 and
purified by column separation (silica gel) to yield 5 as a white solid (900 mg,
76%). Mp: 32–34 °C. 1H NMR (300 MHz, CDCl3): d 7.89–7.84 (m, 2H), 7.38–7.32
(m, 2H), 6.86 (d, J = 7.6 Hz, 2H), 4.31–4.29 (m, 4H), 4.01–3.98 (m, 4H), 4.00–
3.97 (m, 2H), 3.82–3.77 (m, 2H), 3.73–3.60 (m, 4H), 3.60–3.56 (m, 2H), 3.52 (q,
J = 7.0 Hz, 2H), 1.20 (t, J = 7.0 Hz, 3H). 13C NMR (100 MHz, CDCl3): d 154.6,
154.5, 127.0, 126.9, 125.4, 125.3, 115.0, 114.7, 105.9, 72.9, 71.2, 70.9, 70.0, 69.9,
68.1, 66.8, 62.0, 15.4. EI-MS m/z calcd for C22H32O7, 408. Found 408. Anal. Calcd
for C22H32O7: C, 64.69; H, 7.90. Found: C, 64.60; H, 7.75. Compound 7: To a
solution of compound 4 (400 mg, 1.10 mmol) and p-toluenesulfonyl chloride
(251 mg, 1.31 mmol) in THF (20 mL), the NaOH (97 mg, 2.4 mmol) dissolved in
1 mL of H2O was added at 0 °C; then the solution was stirred at room
temperature for 12 h. After evaporation of the solvent, the crude product was
dissolved in CH2Cl2 (50 mL) and the solution was washed with water
(3 ꢃ 10 mL). The solution was dried with Na2SO4. The solvent was
evaporated and the crude product was chromatographed to give 7 (520 mg,
91%) as a pale yellow oil. 1H NMR (400 MHz, CDCl3): d 7.88 (d, J = 8.5 Hz, 1H),
7.83 (d, J = 8 Hz, 2H), 7.62 (d, J = 8.5 Hz, 1H), 7.32–7.27 (m, 4H), 6.85 (d,
J = 7.6 Hz, 1H), 6.72 (d, J = 7.6 Hz, 1H), 4.51–4.49 (m, 2H), 4.32–4.28 (m, 4H),
4.01–3.98 (m, 2H), 3.81–3.76 (m, 2H), 3.72–3.66 (m, 4H), 3.60–3.57 (m, 2H),
3.52 (q, J = 7.0 Hz, 2H), 2.41 (s, 1H), 1.20 (t, J = 7.0 Hz, 3H). 13C NMR (150 MHz,
CDCl3): d 154.4, 153.5, 145.0, 133.0, 130.0, 128.1, 126.9, 126.6, 125.3, 124.9,
115.3, 114.5, 105.8, 105.6, 71.1, 70.8, 69.9, 68.2, 68.0, 66.7, 65.6, 21.7, 15.3. EI-
MS m/z calcd for C27H34O8S, 518. Found 518. Anal. Calcd for C27H34O8S: C,
62.53; H, 6.61. Found: C, 62.50; H, 6.56. Compound 8: Compound 5 (400 mg,
0.98 mmol) and p-toluenesulfonyl chloride (225 mg, 1.17 mmol) were allowed
to react in the same way as described for 7 and purified by column separation
(silica gel) to yield 8 (520 mg, 94%) as a pale yellow oil. 1H NMR (400 MHz,
CDCl3):d 7.89 (d, J = 8.5 Hz, 1H), 7.81 (d, J = 8.0 Hz, 1H), 7.78 (d, J = 8.5 Hz, 2H),
7.34 (t, J = 8.0 Hz, 2H), 7.25 (d, J = 8.0 Hz, 2H), 6.86 (d, J = 7.6 Hz, 1H), 6.81 (d,
J = 7.6 Hz, 1H), 4.30 (t, J = 4.7 Hz, 2H), 4.23–4.19 (m, 4H), 4.00 (t, J = 4.7 Hz, 2H),
3.91 (t, J = 4.7 Hz, 2H), 3.84–3.80 (m, 4H), 3.73–3.66 (m, 4H), 3.60–3.58 (m, 2H),
3.52 (q, J = 7.0 Hz, 2H), 2.36 (s, 1H), 1.20 (t, J = 7.0 Hz, 3H). 13C NMR (150 MHz,
CDCl3): d 154.5, 154.3, 145.8, 133.0, 130.0, 128.0, 126.9, 126.8, 125.3, 125.1,
114.9, 114.6, 105.8, 105.7, 71.1, 70.8, 70.0, 69.9, 69.4, 69.1, 68.0, 67.9, 66.7,
21.7, 15.3. EI-MS m/z calcd for C29H38O9S, 562. Found 562. Anal. Calcd for
C
29H38O9S: C, 61.90; H, 6.81. Found: C, 61.88; H, 6.75. Compound 9: To a
solution of compound 3 (150 mg, 0.47 mmol) in DMF (10 mL), triethylene-
glycol-di(p-toluenesulfonate) (430 mg, 0.94 mmol) and K2CO3 (130 mg,
0.94 mmol) were added. The solution was heated at 80 °C for 12 h. The
solvent was evaporated and CH2Cl2 (50 mL) was added. The solution was
washed with water (3 ꢃ 10 mL) and then dried over anhydrous MgSO4. The
crude product was chromatographed to give 9 (200 mg, 70%) as a colorless oil.
1H NMR (400 MHz, CDCl3): d 7.88–7.83 (m, 4H), 7.78 (d, J = 8 Hz, 2H), 7.34 (t,
J = 8 Hz, 2H), 7.29 (d, J = 8 Hz, 2H), 6.85–6.82 (m, 2H), 4.30–4.25 (m, 4H), 4.15–
4.13 (m, 2H), 3.99 (t, J = 4.7 Hz, 2H), 3.94 (t, J = 4.7 Hz, 2H), 3.82–3.79 (m, 2H),
3.73–3.57 (m, 12H), 3.52 (q, J = 7.0 Hz, 2H), 2.39 (s, 1H), 1.20 (t, J = 7.0 Hz, 3H).
13C NMR (150 MHz, CDCl3): d 154.5, 154.4, 144.9, 133.1, 129.9, 128.0, 126.9,
126.8, 125.2, 125.1, 114.8, 114.6, 105.8, 77.4, 77.2, 77.0, 71.1, 71.0, 70.9, 70.8,
10. (a) Bria, M.; Cooke, G.; Cooper, A.; Garety, J. F.; Hewage, S. G.; Nutley, M.;
Rabani, G.; Woisel, P. Tetrahedron Lett. 2007, 48, 301; (b) Liu, Y.; Flood, A. H.;
Stoddart, J. F. J. Am. Chem. Soc. 2004, 126, 9150.
11. Matthews, O. A.; Raymo, F. M.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. New.
J. Chem. 1998, 1131.
12. (a) Harris, S. J.; Barrett, G.; Mckervey, M. A. Chem. Commun. 1991, 1224;
(b) Gutsche, C. D.; Dhawan, B.; Levine, J. A.; No, K. H.; Bauer, L. J.
Tetrahedron 1983, 39, 409; (c) Iwamoto, K.; Shinkai, S. J. Org. Chem. 1992,
57, 7066.
13. Binding constant of the tetraethyl ester calix[4]-arene with K+ in acetonitrile at
298 K is 104.5, see (a) Arnaud-Neu, F.; Collins, E. M.; Deasy, M.; Ferguson, G.;
Harris, S. J.; Kaitner, B.; Lough, A. J.; McKervey, M. A.; Marques, E.; Ruhl, B. L.;

J. Li et al. / Tetrahedron Letters 49 (2008) 4857–4861
4861
69.9, 69.4, 68.8, 68.0, 66.7, 21.7, 15.3. EI-MS m/z calcd for C31H42O10S, 606.
Found 606. Anal. Calcd for C31H42O10S: C, 61.37; H, 6.98. Found: C, 61.50; H,
6.90. Compound CN1. Compound 7 (200 mg, 0.39 mmol), Calix–COOH (310 mg,
0.32 mmol) and K2CO3 (45 mg, 0.64 mmol) were added to DMF (20 mL). The
solution was stirred for 10 h at room temperature. Then the solvent was
evaporated and CH2Cl2 (50 mL) was added. The solution was washed with
H2O(3 ꢃ 10 mL). The solution was dried over anhydrous MgSO4 and the solvent
was evaporated. The oil product was chromatographed to obtain the CN1
(350 mg, 83%) as a colorless oil. 1H NMR (400 MHz, CDCl3): d 7.90 (d, J = 8.5 Hz,
1H), 7.86 (d, J = 8.5 Hz, 1H), 7.33 (q, J = 8 Hz, 2H), 6.85–6.76 (m, 6H), 6.75–6.70
(m, 4H), 5.00–4.63 (m, 14H), 4.36–4.29 (m, 4H), 4.20–4.15 (m, 6H), 4.01 (t,
J = 4.7 Hz, 2H), 3.83–3.81 (m, 2H), 3.73–3.67 (m, 4H), 3.61–3.59 (m, 2H), 3.52
(q, J = 7.0 Hz, 2H), 3.22–3.17 (m, 4H), 1.25–1.20 (m, 12H), 1.13–1.03 (m, 36H).
13C NMR (100 MHz, CDCl3): d 170.7, 170.6, 170.4 154.3, 154.0, 153.1, 153.0,
152.8, 145.2, 145.1, 133.7, 133.6, 133.2, 133.1, 124.9, 114.9, 114.5, 105.7, 105.5,
71.0, 70.9, 70.7, 69.8, 67.9, 66.6, 66.2, 62.5, 60.4, 60.3, 33.8, 31.8, 31.4, 31.3,
31.0, 15.2, 14.2. MALDI-TOF m/z calcd for C78H102O17, 1310.7. Found: 1333.9
(M+Na)+, 1391.9 (M+K)+. Anal. Calcd for C78H102O17: C, 71.42; H, 7.84. Found: C,
71.33; H, 7.76. Compound CN2. Compound 8 (140 mg, 0.25 mmol), Calix–
COOH (200 mg, 0.21 mmol) and K2CO3(100 mg, 0.42 mmol) were allowed to
react in the same way as described for CN1 and purified by column separation
(silica gel) to yield CN2 (200 mg, 73%) as a colorless oil. 1H NMR (400 MHz,
CDCl3): 7.88–7.83 (m, 2H), 7.36–7.31 (m, 2H), 6.84–6.75 (m, 10H), 4.88–4.79
(m, 12H), 4.35–4.26 (m, 6H), 4.21–4.18 (m, 6H), 4.01–3.98 (m, 4H), 3.85–3.80
(m, 4H), 3.73–3.66 (m, 4H), 3.60–3.58 (m, 2H), 3.52 (q, J = 7.0 Hz, 2H), 3.21–
3.17 (m, 4H), 1.28–1.19 (m, 12H), 1.08–1.05 (m, 36H). 13C NMR (75 MHz,
CDCl3): d 170.7, 154.4, 153.1, 145.3, 133.6, 126.9, 125.5, 125.3, 114.9, 114.6,
105.8, 71.5, 71.2, 70.9, 70.0, 69.5, 68.0, 66.8, 63.6, 60.5, 34.0, 32.0, 31.5, 15.3,
14.4. MALDI-TOF m/z calcd for C80H106O18, 1354.7. Found: 1377.9 (M+Na)+,
1435.9 (M+K)+. Anal. Calcd for C80H106O18: C, 70.88; H, 7.88. Found: C, 71.03; H,
7.95. Compound CN3. Compound
9 (150 mg, 0.25 mmol), Calix–COOH
(199 mg, 0.21 mmol) and K2CO3 (100 mg, 0.42 mmol) were allowed to react
in the same way as the described for CN1 and purified by column separation
(silica gel) to yield CN3 (210 mg, 76%) as a colorless oil. 1H NMR (400 MHz,
CDCl3): 7.87–7.83 (m, 2H), 7.36–7.31 (m, 2H), 6.84–6.75 (m, 10H), 4.94–4.70
(m, 12H), 4.30–4.26 (m, 6H), 4.21–4.18 (m, 6H), 4.01–3.98 (m, 4H), 3.81–3.76
(m, 4H), 3.72–3.66 (m, 8H), 3.60–3.58 (m, 2H), 3.52 (q, J = 7.0 Hz, 2H), 3.21–
3.17 (m, 4H), 1.28–1.19 (m, 12H), 1.08–1.05 (m, 36H).13C NMR (100 MHz,
CDCl3): d 170.8, 170.7, 154.6, 154.5, 153.2, 145.4, 133.7, 133.6, 133.5, 126.9,
125.6, 125.3, 125.2, 114.9,114.8, 105.9, 71.6, 71.2, 71.0, 70.1, 69.3, 68.1, 66.9,
63.6, 60.6, 34.0, 32.1, 31.6, 15.4, 14.4, 14.3. MALDI-TOF m/z calcd for
C
C
82H110O19, 1398.7. Found: 1421.9 (M+Na)+, 1479.9 (M+K)+. Anal. Calcd for
82H110O19: C, 70.36; H, 7.92. Found: C, 70.31; H, 7.90.
15. (a) Northrop, B. H.; Khan, S. J.; Stoddart, J. F. Org. Lett. 2006, 8, 2159; (b) Dichtel,
W. R.; Miljanic’, O. S.; Spruell, J. M.; Heath, J. R.; Stoddart, J. F. J. Am. Chem. Soc.
2006, 128, 10388.
16. Ikeda, T.; Aprahamian, I.; Stoddart, J. F. Org. Lett. 2007, 9, 1481.
17. Cooke, G.; Garety, J. F.; Hewage, S. G.; Jordan, B. J.; Rabani, G.; Rotello, V. M.;
Woisel, P. Org. Lett. 2007, 9, 481.
18. (a) Connors, K. A. Binding Constant; Wiley: New York, 1987.
p 148; (b)
Bernardo, A. R.; Stoddart, J. F.; Kaifer, A. E. J. Am. Chem. Soc. 1992, 114, 10624;
(c) Goodnow, T. T.; Reddington, M. V.; Stoddart, J. F.; Kaifer, A. E. J. Am. Chem.
Soc. 1991, 113, 4335.
19. Nygaard, S.; Hansen, C. N.; Jeppesen, J. O. J. Org. Chem. 2007, 72, 1617.