Donor-acceptor interaction-mediated arrangement of hydrogen bonded dimers

Article abstract of DOI:10.1016/j.tet.2004.06.104

The donor-acceptor interaction-driven supramolecular arrangement of a new series of quadruply hydrogen-bonded homo- and heterodimers have been investigated in chloroform with ¹H NMR and UV-Vis spectroscopy. Two kinds of structurally complementa

Full text of DOI:10.1016/j.tet.2004.06.104

Tetrahedron 60 (2004) 8275–8284
Donor–acceptor interaction-mediated arrangement of hydrogen
bonded dimers
*
Xiao-Qiang Li, Dai-Jun Feng, Xi-Kui Jiang and Zhan-Ting Li
Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
Received 23 April 2004; revised 4 June 2004; accepted 7 June 2004
Available online 21 July 2004
Abstract—The donor–acceptor interaction-driven supramolecular arrangement of a new series of quadruply hydrogen-bonded homo- and
heterodimers have been investigated in chloroform with H NMR and UV–Vis spectroscopy. Two kinds of structurally complementary
1
monomers have been prepared. Monomers 3 and 4 are incorporated with one ureidopyrimidone unit and one electron deficient pyromellitic
diimide (PDI) or naphthalene diimide (NDI) unit, respectively, monomers 5 and 6 are incorporated with two ureidopyrimidone units and one
PDI or NDI unit, respectively, whereas monomers 7 and 8 consist of one electron rich bis-p-phenylene[34]crown-10 unit and one or two
2,7-diamido-1,6-naphthyridine units, respectively. Compounds 3 and 4 exist exclusively as homodimers, respectively. Adding 1 equiv. of 7
to the solution of 3$3 and 4$4 induced them to partially or fully dissociate to produce heterodimers 3$7 and 4$7 due to intermolecular donor–
acceptor interaction and the formation of a new binding mode between the ureidopyrimidone of 3 or 4 and the 2,7-diamido-1,6-naphthyridine
unit of 7. Both 5 and 6 exist as cyclic monomer and dimer in chloroform. Adding 1 equiv. of 8 to the solution of 5 or 6 in chloroform caused
all the cyclic dimer and most of the cyclic monomer to de-cyclize to form new heterodimers 5$8 and 6$8, respectively. 1H NMR and UV–vis
study revealed that heterodimer 5$8 has a structure in which the PDI of 5 is not threaded through the cavity of the bis-p-phenylene[34]crown-
10 unit of 8. In contrast, in addition to the heterodimer similar to 5$8, about 40% of heterodimer 6$8 is generated, in which the PDI of 6 is
threaded through the cavity of the bis-p-phenylene[3]crown-10 unit of 8 due to the increased donor–acceptor interaction between NDI and
bis-p-phenylene[34]crown-10. Steric hindrance and mismatching of the hydrogen bonding moiety play important roles in the arrangement of
the new homo- and heterodimers.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
examples of supramolecular assemblies of such kind are
notably few.7
Nature utilizes the cooperative interaction of discrete non-
covalent forces, including hydrogen bonding, hydrophobic
interaction, metal-ligand coordination, and aromatic stack-
ing, to construct the three dimensional structures and
functions of biomacromolecules.1 One of the major aspects
of supramoleulcar chemistry is to produce new well-defined
unnatural assemblies in a selective and directional way.2 In
the past decade, a large number of artificial supramolecular
architectures have been assembled based on single non-
covalent force, such as transition metal-ligand interaction,3
hydrogen bonding,4 or electrostatic interaction,5 and
hydrophobic interaction.6 Although in principle two or
more different non-covalent interactions may also
function well together, as shown by Nature, to generate
supramolecular systems of defined structures and functions,
Since its first reported by Meijer et al. in 1998,8 the highly
stable, self-complimentary 2-ureido-4[1H]-pyrimidinone-
based AADD-styled (A: hydrogen bonding acceptor, D:
hydrogen bonding donor) quadruple hydrogen bonding
motif has found extensive applications in self-assembly of
discrete supramolecular systems with well-established
structures.9,10 In search of efficient methods for selective
formation of heterodimeric structures from this versatile
self-binding mode, we recently reported that more stable
Keywords: Hydrogen bonding; Donor–acceptor interaction; Self-assembly;
Heterocyclic compounds; Arrangement.
* Corresponding author. Tel.: C86-21-64163300; fax: C86-21-
64166128.; e-mail: ztli@mail.sioc.ac.cn
Chart 1.
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.06.104

8276
X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
Chart 2.
ADDA–DAAD hydrogen bonded heterodimer 1$2 could be
exclusively formed from homodimer 1$1 and diamide 2 in
chloroform (Chart 1).11–13 Previously, we had also found
that two different homodimers could also decompose to
form new quadruple hydrogen bonding heterodimers,13,14 as
a result of additional intermolecular donor–acceptor inter-
action between electron-rich bis-p-phenylene-[34]crown-10
moiety and electron-deficient pyromellitic diimide (PDI)
or naphthalene diimide (NDI) unit.5c,15 The generation
of hydrogen bonded heterodimers from related homo-
dimers driven by additional donor–acceptor interaction
represents a new useful strategy for constructing novel
kind of supramolecular architectures based on two different
non-covalent forces. In this paper, we describe that this
strategy has been utilized for the self-assembly of a novel
series of structurally unique hydrogen bonded heterodimers,
which are driven by intermolecular donor–acceptor
interaction.
2. Results and discussion
Compounds 3-8 have been designed and synthesized for the
present study (Chart 2). It was expected that in chloroform
the identical equivalent of 3 or 4 and 7 will form
heterodimers with a binding mode similar to that of 1$2,
which would also be facilitated by the intermolecular
electrostatic interaction between the electron deficient PDI
unit of 3 or NDI unit of 4 and the electron rich bis-p-
phenylene[34]crown-10 unit, while the binding of 5 or 6
with 8 would produce a macrocyclic dimer, in which the
PDI of 5 or NDI of 6 is threaded through the cavity of bis-p-
phenylene[34]crown-10 of 8 due to the intermolecular
donor–acceptor interaction (Chart 3).
The preparation of 3 and 4 has been described in a recent
report.13 Initial attempts to prepare compounds similar to 5
and 6 but with the linker of 3 or 4 did not succeed. The
Chart 3.

X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
8277
synthesis of 5 and 6 is shown in Scheme 1. Thus, diacid 9
was first produced from the reaction of pyromellitic
dianhydride and 3-amino propionic acid in hot DMF and
then converted into 10 with oxalyl chloride in THF.
Subsequent reaction of 10 with 1113 in refluxing chloroform
in the presence of triethylamine afforded 5 in 33% yield. For
the preparation of 6, 12 was first produced from naphtha-
lene-1,4,5,8-tetracarboxylic dianhydride and 3-amino pro-
pionic acid in hot DMF and then transformed into 13. The
reaction of 13 with 11 in chloroform gave compound 6 in
29% yield.
For the preparation of 7 (Scheme 2), compound 16 was first
prepared in 61% yield from the palladium-catalyzed
reaction of 14 and 15 in hot pyrrolidine. Treatment of 16
with oxalyl chloride in dichloromethane yielded acyl
chloride 17, which was used for the next step without
purification. Compound 20 was then prepared in 67% yield
from the reaction of 18 and 1914a in refluxing chloroform
and hydrolyzed with sodium hydroxide in aqueous ethanol
to 21 in 75% yield. Compound 21 could not be directly
obtained from the reaction of 18 and 19 because it was
converted into 20 upon being generated. Finally, the
reaction of 21 with 17 in refluxing chloroform produced 7
in 49% yield.
Scheme 1.
Scheme 2.
Scheme 3.

8278
X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
The synthetic route for 8 is shown in Scheme 3. Phenol 22
was first treated with excessive amount of 23 in refluxing
acetonitrile to give bromide 24 in 40% yield. Palladium-
catalyzed hydrogenation of 24 in ethyl acetate afforded 25
quantitatively. Compound 25 was then reacted with bromine
to produce 26 in 95% yield. Macrocycle 27 was obtained in
56% yield from 26 in refluxing acetonitrle in the presence of
potassium carbonate and then coupled with 15 to afford 28
in 48% yield. Compound 28 was then converted into 29 with
oxalyl chloride, and 29 was reacted with 21 in refluxing
chloroform to afford 8 in 30% yield. The dioctylmethyl
chain provides good solubility to 7 and 8 in common organic
solvents such as chloroform and dichloromethane.
for 3$3 (Fig. 1a–c). The signals for 3$3 had been assigned
by changing the ratio of 3 and 7 in the solution, while the
ADDA-DAAD binding mode of 3$7 had been established
1
by the H NMR NOESY experiment.11–13 Based on the
relative integrating intensity of the H-1 signal of both
dimers, we determined the yield of heterodimer 3$7 to be ca.
80%. The solution of the 1:1 mixture of 3 and 7 (5 mM) in
chloroform also turned pale orange. The UV–vis spectrum
exhibited a typical charge-transfer absorption band (lmax
Z
465 nm, 3Z45 MK1cmK1), which provides additional
evidence for the formation of heterodimer 3$7. Controlling
experiment had revealed that no detectable absorption
within 400–700 nm could be observed for the 1:1 mixture of
a donor compound and an acceptor compound bearing no
hydrogen bonding moiety in chloroform even at higher
concentration.13,16Therefore, the charge-transfer absorption
was obviously generated as a result of the donor–acceptor
interaction between the PDI unit of 3 and the bis-p-
phenylene[34]crown-10 moiety of 7 in heterodimer 3$7. In
addition, the solution of the 1:1 mixture of 3 and 7 in
Previous study had revealed that both 3 and 4 exist
exclusively as homodimer 3$3 and 4$4 in chloroform,
respectively, and the PDI and NDI unit have no important
effect on the stability of the dimers.13 Adding 1 equiv. of 7
to the solution of 3$3 in chloroform-d caused the dimer to
partially dissociate to form new heterodimer 3$7 (Chart 4).
1
1
DMSO-d6 is colorless, and the H NMR spectrum reveals
The evidence came from the H NMR spectrum, which
shows one set of signals for 3$7 and another set of signals
only the signals of 3 and 7, due to the highly competitive
interaction of the solvent. The fact that only 80% of dimer
3$3 was converted into 3$7 by 1 equiv. of 7 is quite different
from the previous observation that 1$2 could be generated
quantitatively from dimer 1$1 and 2. This may be attributed
to the greater steric hindrance of the dioctylmethyl group
relative to the undecyl group.
Mixing 1 equiv. of 7 with 1 equiv. of 4 in chloroform-d
caused full disruption of dimers 4$4, exclusively affording
heterodimer 4$7 (Chart 4), as indicated by the H NMR
1
1
spectrum (Fig. 1c–e). No detectable H NMR signals of
homodimer 4$4 were observed from the 1H NMR spectrum
within the temperature range of K10 to 55 8C. This
observation clearly demonstrates that the strengthened
donor–acceptor interaction between the bis-p-phenyle-
ne[34]crown-10 moiety of 7 and the NDI unit of 4
remarkably stabilizes the hydrogen bonded heterodimer
4$7 in chloroform.17 A typical, but obviously stronger
charge-transfer absorption band was also displayed for
heterodimer 4$7 in chloroform (lmaxZ470 nm, 3Z139 MK
1 cmK1). Within the measurable concentration range of
10–0.5 mM, the 3 value is concentration-independent,
proving the extremely high stability of the heterodimer,
which is reminiscent of that produced from intramolecular
interaction.
Chart 4.
The 1H NMR spectrum of a relatively concentrated solution
(75 mM) of 5 in chloroform-d displayed two sets of signals
that are typical for the hydrogen bonded NH protons (Fig.
2a). The relatively weaker set of signals (ca. 18% based on
the relative intensity of the NH signal) was decreased in
magnitude upon dilution and vanished when the solution
was diluted to 1.1 mM. The viscosity of the solution was
almost unchanged (!20%) when diluting the solution 110–
1.0 mM. This result indicates that no important amount of
linear supramolecular polymers of 5 were formed in the
solution, which otherwise should cause remarkable increase
of viscosity at the range of high concentration. Molecular
modeling revealed that compound 5 can cyclize intra-
molecularly. In addition, recent study by Meijer had also
demonstrated that flexible linker-connected bifunctional
Figure 1. Partial 400 MHz 1H NMR spectrum (5 mM) of (a) 3, (b) 3C7
(1:1), (c) 7, (d) 4C7, and (e) 4 in CDCl3 at 25 8C.

X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
8279
Figure 3. Partial 1H NMR (400 MHz) spectrum of (a) 5 (10 mM), (b) 5
(10 mM)C8 (5 mM), (c) 5 (10 mM)C8 (10 mM), and (d) 5 (1.5 mM)C8
(1.5 mM) in chloroform-d.
the cyclic dimer was completely converted into the cyclic
monomer at [6]Z1.9 mM (Fig. 2e).
Adding 8 to the solution of 5 in chloroform-d first caused the
less stable cyclic dimer 5$5 to decompose to produce new
heterodimer 5$8 (Fig. 3a and b). With more amount
(1 equiv.) of 8 added, the more stable cyclic monomer 5
also began to de-cyclize to form 5$8 (in ca. 50% yield in the
1:1 mixture of 5 and 8, Figure 3c). Dilution of the 1:1
mixture of 5 and 8 in chloroform-d did not have dramatic
effect on the ratio of heterodimer 5$8 and cyclic monomer 5
(Fig. 3d). Since no detectable charge-transfer absorption
band was observed in the UV–vis spectrum of the 1:1
mixture of 5 and 8 (10 mM) in chloroform and the solution
is colorless, it is reasonable to propose that the new
heterodimer 5$8 in the mixture actually possess a binding
mode in which the PDI unit is not threaded through the
cavity of the bis-p-phenylene[34]crown-10 unit of 8, as
shown in Chart 6, due to the flexibility of the linkers
between the binding moieties and the weakness of the
electrostatic interaction between the PDI unit of 5 and the
bis-p-phenylene[34]crown-10 moiety of 8.
Figure 2. Partial 1H NMR (400 MHz) spectrum of 5 at (a) 75 mM,
(b) 25 mM, and (c) 1.1 mM and 6 at (d) 50 mM and (e) 1.5 mM in
chloroform-d.
2-ureido-4[1H]-pyrimidinone derivatives preferred to form
cyclic structures over linear oligomers and polymers.18
1
Therefore, the two sets of signals shown in the H NMR
spectra can be reasonably assigned to those of cyclic
monomer 5 (ca. in 82% yield) and cyclic dimer 5$5 (Chart
5), respectively, and upon dilution dimer 5$5 was gradually
converted into the more stable cyclic monomer 5 (Fig. 2b
and c). 1H NMR spectroscopy revealed that 6 also existed as
cyclic monomer and cyclic dimer (ca. 40% and 60%,
respectively, at [6]Z75 mM in chloroform-d (Fig. 2d) and
Addition of 1 equiv. of 8 to the solution of 6 in chloroform-d
also caused all the cyclic dimer 6$6 and most cyclic
monomer 6 to dissociate, as indicated by the 1H NMR
spectra (Fig. 4a–c). Different from that observed for the
mixture of 5 and 8, the 1NMR spectrum of the 1:1 mixture of
6 and 8 displayed two new sets of signals, which we
attributed to the formation of two new isomeric hetero-
dimers 6$8. One is that in which the NDI unit of 6 is not
threaded through the cavity of the bis-p-phenylene[34]-
crown-10 unit of 8 (Chart 6). Another one is that in which
the NDI unit of 6 is threaded through the cavity of the bis-p-
phenylene[34]crown-10 unit of 8, as shown in Chart 3.
UV–vis spectrum recorded in chloroform provides evidence
that the threaded heterodimer 6$8 was generated, which
showed a typical charge-transfer absorption band at lmax
Z
470 that is not available for dimer 5$8. The apparent molar
absorption coefficient 3 was determined to be 450 MK1
cmK1, which was also concentration-independent within the
measurable range of concentration of R0.8 mM. This result
can be explained by considering the increased, intermole-
cular steric hindrance within heterodimer 6$8 and also the
stacking weakening between the NDI unit of 6 and the bis-p-
phenylene[34]-crown-10 unit of 8 due to the hydrogen
bonded moiety-induced mismatching and the longer flexible
Chart 5.

8280
X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
Chart 6.
linkers between the binding moiety. The formation of the
threaded heterodimer 6$8 but not 5$8 is consistent with the
stronger donor–acceptor interaction between NDI and bis-p-
phenylene[34]crown-10 than that between PDI and bis-p-
phenylene[3]crown-10.15 The yields of the threaded and
unthreaded heterodimers 6$8 are comparable, and have been
estimated to be approximately 45%, based on the integrating
Adding 1 equiv. of compound 30, which is prepared from 21
and 31 in refluxing chloroform (Scheme 4), to the solution
of 5 or 6 in chloroform-d also caused similar de-cyclization
of the latter’s cyclic dimer and monomer. However, the new
signals are quite broadened (Fig. 4e), suggesting that more
cyclic or linear oligomers are formed between 30 and 5 or 6.
1
intensity of their NH signals in the H NMR spectrum.
3. Conclusion
We have reported the self-assembly of a new series of
multiply hydrogen-bonded heterodimers based on the
quadruple hydrogen bonding DAAD–ADDA mode between
ureidopyrimidone and 2,7-diamino-1,6-naphthyridine dia-
mide monomers. The assembling efficiency of the relatively
complicated supramolecular structures is reduced remark-
ably due to the possible steric hindrance and the structural
flexibility of the linkers between the hydrogen bonding and
the electrostatic binding moieties. It is expected that, by
rigidifying the linking groups and reducing the steric
hindrance produced by the peripheral aliphatic groups in
8, more selective self-assembly of heterodimers similar to
threaded dimers 6$8 or other related supramolecular
architectures might be constructed, which is being investi-
gated in our lab.
Figure 4. Partial 1H NMR (400 MHz) spectrum of (a) 6 (15 mM), (b) 6
(15 mM)C8 (7.5 mM), (c) 6 (15 mM)C8 (15 mM), (d) 6 (2 mM)C8
(2 mM), and (e) 6 (15 mM)C30 (15 mM) in chloroform-d.
4. Experimental
4.1. General methods
Melting points are uncorrected. All reactions were carried
out under an atmosphere of nitrogen. The H NMR spectra
1
were recorded on 400 or 300 MHz spectrometers in the
indicated solvents. Chemical shifts are expressed in parts
per million (d) using residual solvent protons as internal
standards. Viscosity was obtained with a NPJ-S viscosi-
meter. Chloroform (d 7.26 ppm) was used as an internal
standard for chloroform-d. Elemental analysis was carried
out at the SIOC Analytical Center. Unless otherwise
indicated, all commercially available materials were used
as received. All solvents were dried before use following
standard procedures.
Scheme 4.

X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
8281
4.1.1. 3,30-(1,3,5,7-Tetraoxo-5,7-dihydro-1H,3H-pyrrolo
[3,4-f]isoindole-2,6-diyl)-bis-propionic acid (9). A mix-
ture of pyrromellitic dianhydride (1.50 g, 6.90 mmol) and
3-aminopropionic acid (1.40 g, 15.7 mmol) in DMF
(10 mL) was stirred at 120 8C for 4 h. Upon cooling to
room temperature, the resulting solid was filtered, washed
with water and acetone thoroughly to afford compound 9 as
a white powder (1.20 g, 48%). Mp >330 8C (Lit.19 329 8C).
1H NMR (DMSO-d6): d 2.40 (t, JZ6.8 Hz, 4H), 3.41 (t, JZ
6.8 Hz, 4H), 7.98 (s, 2H). MS (ESI): m/z 361 [MCH]C.
Anal. Calcd for C16H12N2O8: C, 53.34; H, 3.36; N, 7.78.
Found: C, 52.99; H, 3.54; N, 7.77.
residue was subjected to flash chromatography (CH2Cl2/
MeOH 200:1) to afford 6 as a yellow solid (150 mg, 29%).
Mp 188–190 8C. IR (cmK1): 3213, 2928, 2856, 1742, 1708,
1
1670, 1585, 1338, 1247, 768. H NMR (CDCl3): d 0.88 (t,
JZ6.0 Hz, 6H), 1.20–1.45 (m, 24H), 1.69–1.71 (m, 4H),
2.46–2.51 (m, 4H), 2.70–2.71 (m, 2H), 3.19–3.28 (m, 4H),
3.69–3.75 (m, 2H), 4.12–4.21 (m, 4H), 4.45 (t, JZ7.2 Hz,
2H), 4.72 (t, JZ12.6 Hz, 2H), 5.72 (s, 2H), 8.47 (s, 4H),
9.80 (s, 2H), 10.82 (s, 2H), 12.74 (s, 2H). MS (ESI): m/z
[MCH]C. Anal. Calcd for C52H66N10O12: C, 61.04; H,
6.50; N, 13.69. Found: C, 61.07; H, 6.74; N, 13.22.
4.1.5. 1,4,7,13,20,23,26,29,32-Decaoxa-15-(4-carboxy-
but-1-ynyl)[13,13]paracyclophane (16). To a stirred
solution of pyrrolidine (4 mL) were added compounds
1413 (0.40 g, 0.65 mmol), Pd(PPh3)4 (80.0 mg, 0.07 mmol,
10%) and 15 (170.0 mg, 1.73 mmol). The reaction mixture
was stirred at 80 8C for 4 h and then cooled to room
temperature. The solvent was evaporated in vacuo and the
residue was triturated with dichloromethane (50 mL). The
organic phase was washed with 1 N hydrochloride (20 mL),
water (20 mL), brine (20 mL), and dried over sodium
sulfate. After the solvent was removed in vacuo, the crude
product was purified by column chromatography (CH2Cl2/
CH3OH 50:1). Compound 16 was obtained as a yellow solid
(0.25 g, 61%). Mp 65–67 8C. IR (cmK1): 3553, 3471, 2882,
2233, 1724, 1604, 1510, 1455, 1234, 839. 1H NMR
(CDCl3): d 2.58 (t, JZ6.0 Hz, 2H), 2.73 (t, JZ6.0 Hz,
2H), 3.71–4.75 (m, 16H), 3.81–3.85 (m, 8H), 3.94–3.97 (m,
8H), 6.55 (d, JZ6.0 Hz, 1H), 6.70–6.75 (m, 5H), 6.89 (d,
JZ3 Hz, 1H). MS (ESI): m/z 633 [MCH]C. Anal. Calcd
for C33H44O12: C, 62.65; H, 7.01. Found: C, 62.54; H, 6.68.
4.1.2. Compound 5. To a solution of 9 (0.10 g, 0.25 mmol)
in THF (5 mL) was added oxalyl chloride (0.2 mL) and 1
drop of DMF. The mixture was heated under reflux for 4 h
and concentrated under reduced pressure to afford crude
compound 10 as an oil, which was used for next step without
further purification. To a stirred solution of compound 11
(0.20 g, 0.62 mmol), NEt3 (0.3 mL) and DMAP (10 mg) in
CHCl3 (15 mL) was added a solution of the above
compound 10 in CHCl3 (5 mL). The mixture was heated
under reflux for 10 h, cooled, washed with dilute aqueous
hydrochloride solution, aqueous sodium carbonate solution,
water, brine and dried over (Na2SO4). After the solvent was
removed in vacuo, the residue was subjected to flash
chromatography (EtOAc/CH2Cl2 2:1) to afford 5 as a white
solid (80 mg, 33%). Mp 232–233 8C. IR (cmK1): 3310,
1
2929, 2856, 1776, 1725, 1656, 1583, 1253, 1182, 725. H
NMR (CDCl3): d 0.90–0.92 (m, 6H), 1.32–1.40 (m, 24H),
1.70–1.72 (m, 4H), 2.52–2.65 (m, 4H), 2.68 (d, d, J1Z
4.8 Hz, J2Z8.7 Hz, 2H), 3.13–3.29 (m, 4H), 3.72–3.76 (m,
2H), 3.85–3.92 (m, 2H), 4.12–4.22 (m, 4H), 4.51–4.53 (m,
2H), 5.78 (s, 2H), 7.91 (s, 2H), 9.96 (s, 2H), 11.24 (s, 2H),
12.92 (s, 2H). MS (ESI): m/z 973 [MCH]C. Anal. Calcd for
C48H64N10O12: C, 59.25; H, 6.63; N, 14.39. Found: C,
59.44; H, 6.39; N, 14.00.
4.1.6. (Dioctyl)acetyl(7-(dioctyl)acetylamino[1,8]naph-
thyri-din-2-yl)amide (20). A suspension of 18 (0.75 g,
2.50 mmol) and 19 (0.16 g, 1.00 mmol), NEt3 (1.00 mL),
and DMAP (20 mg) in chloroform (100 mL) was heated
under reflux for 10 h. Upon cooling to room temperature,
the insoluble material was filtered off and the filtrate was
washed with water, brine, and dried over sodium sulfate.
Upon removal of the solvent under reduced pressure, the
crude product was purified by column chromatography
(hexane/CH2Cl2 5:1 to 1:2) to afford 20 as a yellowish oil
(67%). 1H NMR (CDCl3): d 0.82–0.86 (m, 12H), 1.23–1.28
(m, 48H), 1.46–1.55 (m, 4H), 1.64–1.74 (m, 4H), 2.29–2.35
(m, 2H), 8.13 (d, JZ9.0 Hz, 2H), 8.48 (d, JZ8.7 Hz, 2H),
8.70 (s, 2H). HRMS (MALDI): m/z 693.6020. Calcd for
C44H77N4O2 [MCH]C: 693.6047.
4.1.3. 3,30-(1,3,6,8-Tetraoxo-1,3,6,8-tetrahydro-benzo
[lmn][3,8]phenanthroline-2,7-diyl)-bis-propionic acid
(12).20 A suspension of 1,4,5,8-naphthalenetetracarboxylic
dianhydride (1.00 g, 3.70 mmol) and 3-amino propionic
acid (0.80 g, 9.00 mol) in DMF was heated at 8C for 4 h.
Upon cooling to room temperature, the mixture was poured
into water (50 mL). The resulting solid was filtered, washed
with water and acetone to give compound 12 as a pink
1
powder (1.20 g, 80%). Mp >300 8C (decomp.). H NMR
(DMSO-d6): 2.53 (t, JZ6.4 Hz, 4H), 3.65 (t, JZ6.4 Hz,
4H), 8.46 (s, 4H). MS (ESI): m/z 411 [MCH]C. Anal. Calcd
for C20H14N2O8: C, 58.54; H, 3.44; N, 6.83. Found: C,
57.95; H, 3.46; N, 6.84.
4.1.7. N-(7-Amino-1,8-naphthyridin-2-yl)-2-octyldecoic
amide (21). A solution of 20 (1.25 g, 1.80 mmol) and
NaOH (0.30 g) in ethanol (20 mL) and water (4 mL) was
heated under reflux for 4 h. After work-up as described for
8, the crude product was purified by column chroma-
tography (CH2Cl2/MeOH 20:1) to obtain 21 as a white solid
(0.57 g, 75%). Mp 197–198 8C. 1H NMR (CDCl3): d 0.82–
0.89 (m, 6H), 1.28–1.39 (m, 24H), 1.43–1.56 (m, 2H), 1.64–
1.73 (m, 2H), 2.26–2.32 (m, 1H), 5.45 (s, 2H), 6.66 (d, JZ
8.4 Hz, 1H), 7.81 (d, JZ8.7 Hz, 1H), 7.94 (d, JZ9.0 Hz,
1H), 8.27 (d, JZ9.0 Hz, 1H), 8.57 (s, 1H). MS (MALDI):
m/z 427 [MCH]C. Anal. Calcd for C26H42N4O: C, 73.20;
H, 9.92; N, 13.13. Found: C, 73.30; H, 9.97; N, 13.04.
4.1.4. Compound 6. To a suspension of 12 (0.21 g,
0.50 mmol) in oxalyl chloride (10 mL) was added two
drops of DMF. The mixture was heated under reflux for 12 h
and concentrated in vacuo to give crude compound 13 as an
oil. To a stirred solution of compound 12 (0.36 g,
1.10 mmol), NEt3 (1.0 mL) and DMAP (10 mg) in chloro-
form (15 mL) was added a solution of the above 13 in
chloroform (8 mL). The mixture was heated under reflux for
12 h, cooled, washed with dilute aqueous hydrochloride
solution, aqueous sodium carbonate solution, water, brine
and dried over (Na2SO4). The solvent was removed and the

8282
X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
4.1.8. Compound 7. To a solution of 16 (0.15 g, 0.39 mmol)
in dichloromethane (5 mL) was added oxalyl chloride
(0.2 mL). The solution was stirred for 0.5 h at room
temperature and then concentrated to give crude 17 as an
oil, which was used directly for next step. To a stirred
solution of 21 (0.17 g, 0.39 mmol), NEt3 (0.5 mL) and
DMAP (10 mg) in chloroform (15 mL) was added a solution
of the above 17 in chloroform (5 mL). The mixture was
heated under reflux for 12 h, cooled, washed with water,
brine, and dried (MgSO4). The solvent was then removed
under reduced pressure and the residue was subjected to
flash chromatography (EtOAc/CH2Cl2 2:1) to afford 7 as a
yellowish oil (0.20 g, 49%). IR (cmK1): 3190, 2926, 2856,
ethoxy]-ethoxy]phenol (26). To a solution of 25 (10.8 g,
31.0 mmol) in dichloromethane (100 mL) in an ice bath was
added dropwise a solution of bromine (1.7 mL, 31.0 mmol)
in dichloromethane (50 mL) within 30 min. The mixture
was stirred at 0 8C for 1 h. Then, aqueous NaHSO3 solution
(5%, 100 mL) was added. Stirring was continued until the
mixture became colorless. The organic phase was washed
with water, brine, and dried over sodium sulfate. Upon
removal of the solvent in vacuo, the crude produce was
purified by flash chromatography (AcOEt/petroleum ether
1:4) to afford compound 26 as a colorless oil (13.0 g, 100%).
1H NMR (CDCl3): d 7.03 (d, JZ3.0 Hz, 1H), 6.92 (d, JZ
9.0 Hz, 1H), 6.92 (d, d, J1Z3.0 Hz, J2Z9.0 Hz, 1H), 5.44
(s, 1H), 4.06–4.03 (m, 2H), 3.84–3.78 (m, 4H), 3.74–3.68
(m, 8H), 3.46 (t, JZ6.0 Hz, 2H). HRMS (EI): Calcd for
C14H20Br2O5Na [MCNa]C: 425.9676. Found: 448.9576.
1
2230, 1703, 1609, 1506, 1287, 1137, 855, 804. H NMR
(CDCl3): d 0.85 (t, JZ6.9 Hz, 6H), 1.20–1.29 (m, 24H),
1.50–1.56 (m, 2H), 1.66–1.73 (m, 2H), 2.24–2.30 (m, 1H),
2.83 (s, 4H), 3.68–3.72 (m, 16H), 3.77–3.87 (m, 8H), 3.94–
4.06 (m, 8H), 6.71–6.73 (m, 6H), 6.88 (d, JZ2.4 Hz, 1H),
8.12 (d, d, J1Z1.5 Hz, J2Z9.0 Hz, 2H), 8.22 (s, 1H), 8.45
(d, d, J1Z9.0 Hz, J2Z13.2 Hz, 2H), 8.67 (s, 1H). 13C NMR
(CDCl3): d 14.1, 15.6, 22.7, 27.6, 29.3, 29.5, 29.7, 31.8,
33.1, 36.6, 49.3, 68.1, 68.1, 68.2, 69.7, 69.7, 69.8, 69.8,
70.7, 70.7, 70.8, 70.8, 70.9, 92.3, 113.6, 114.1, 114.6, 115.5,
115.6, 116.1, 118.4, 118.7, 139.0, 139.1, 152.8, 153.0,
4.1.12. 1,4,7,13,20,23,26,29,32-Decaoxa-15,34-dibromo-
[13,13]paracyclophane (27). A suspension of phenol 26
(0.85 g, 2.00 mmol) and potassium carbonate (1.40 g,
10.0 mmol) in acetonitrile (80 mL) was heated under reflux
for 24 h and then cooled to room temperature. The solid was
filtered off and the filtrate was concentrated under reduced
pressure. The resulting residue was triturated with dichloro-
methane (100 mL) and the organic phase was washed with
dilute sodium carbonate solution, water, brine, and dried
over sodium sulfate. Upon removal of the solvent in vacuo,
the crude produce was purified by column chromatography
(CH2Cl2/AcOEt 2:1) to afford 27 as a white solid (0.38 g,
153.0, 153.7, 154.0, 154.0, 154.0, 170.9, 175.8. MS
. Calcd for
C
(MALDI): m/z 1041.6153 [MCH]
C59H85N4O12: 1041.6158.
4.1.9. 4-[2-[2-[2-(2-Bromo-ethoxy)-ethoxy]-ethoxy]-
ethoxy]-phenyl benzyl ether (24). A mixture of 22
(5.70 g, 28.0 mmol), 2321 (45.0 g, 0.14 mol), and potassium
carbonate (7.00 g, 70.0 mmol) in dry acetone (200 mL) was
stirred at room temperature for 1 h and then under reflux for
another 36 h. Upon cooling to room temperature, the solid
was filtered and washed with chloroform. The filtrate was
concentrated under reduced pressure and the resulting
residue was triturated with ether (300 mL). The organic
phase was washed with dilute Na2CO3 solution (1 N), water,
brine, and dried over sodium sulfate. After the solvent was
removed in vacuo, the crude product was purified by column
chromatography (petroleum ether/AcOEt 6:1) to afford the
1
56%). Mp 104–106 8C. H NMR (CDCl3): d 7.08 (d, JZ
3.0 Hz, 2H), 6.78 (d, JZ9.0 Hz, 2H), 6.73 (d, d, J1Z9.0 Hz,
J2Z3.0 Hz, 2H), 4.04–4.07 (m, 4H), 3.99–3.96 (m, 4H),
3.88–3.85 (m, 4H), 3.83–3.80 (m, 4H), 3.78–3.75 (m, 4H),
3.70–3.64 (m, 12H). MS (EI): m/z 694 [M]C. Anal. Calcd
for C28H38Br2O10: C, 48.43; H, 5.52. Found: C, 48.44; H,
5.51.
4.1.13. 1,4,7,13,20,23,26,29,32-Decaoxa-15,34-di(4-car-
boxy-but-1-ynyl)[13,13]paracyclophane (28). To a stirred
solution of pyrrolidine (4 mL) were added compound 27
(0.30 g, 0.43 mmol), Pd(PPh3)4 (80.0 mg, 0.070 mmol,
10%) and 15 (0.30 g, 3.00 mmol). The reaction mixture
was stirred at 80 8C for 4 h and then cooled to room
temperature. The solvent was evaporated in vacuo and the
residue was triturated with dichloromethane (50 mL). The
organic phase was washed with 1 N hydrochloride, water,
brine, and dried over sodium sulfate. After the solvent was
removed in vacuo, the crude product was purified by column
chromatography (CH2Cl2–CH3OH (50:1). Compound 28
was obtained as a yellow solid (0.15 g, 48%). Mp 108–
110 8C. IR (cmK1): 3110, 3045, 2912, 2868, 2233, 1729,
1
desired product as a white solid (5.00 g, 40%). H NMR
(CDCl3): d 7.45–7.32 (m, 5H), 6.92–6.83 (m, 4H), 5.01 (s,
2H), 4.10–4.07 (m, 2H), 3.85–3.68 (m, 12H), 3.47 (t, JZ
6.0 Hz, 2H). MS (EI): m/z 438 [M]C. Anal. Calcd for
C21H27BrO5: C, 57.41; H, 6.19. Found: C, 57.64; H, 6.15.
4.1.10. 4-[2-[2-(2-Propoxyethoxy)-ethoxy]-ethoxy]phenol
(25). A suspension of compound 24 (2.30 g, 4.40 mmol) and
Pd–C (10%, 0.20 g) in ethyl acetate (100 mL) was stirred at
room temperature under 1 atom of hydrogen gas for 8 h. The
solid was then removed by filtration through celite and
washed with dichloromethane. The combined filtrate was
evaporated under reduced pressure and the resulting residue
was purified by column chromatography (CH2Cl2/AcOEt
30:1) to afford compound 25 as a colorless oil (15.0 g, 98%).
1H NMR (CDCl3, 300 Hz): d 6.74 (d, JZ1.2 Hz, 4H), 5.58
(s, 1H), 4.03–4.00 (m, 2H), 3.83–3.77 (m, 4H), 3.75–3.67
(m, 8H), 3.44 (t, JZ6.0 Hz, 2H). MS (EI): m/z 348 [M]C.
Anal. Calcd for C14H21BrO5: C, 48.15; H, 6.06. Found: C,
48.02; H, 5.92.
1
1604, 1505, 1236, 842, 802. H NMR (CDCl3): d 2.61 (t,
JZ6.9 Hz, 4H), 2.76 (t, JZ6.6 Hz, 4H), 3.71–4.73 (m,
12H), 3.79–3.83 (m, 8H), 3.90 (s, 12H), 6.56 (d, JZ9.0 Hz,
2H), 6.72 (d, d, J1Z3 Hz, J2Z9.3 Hz, 2H), 6.88 (d, JZ
3 Hz, 2H). MS (ESI): m/z 752 [MCNa]C. Anal. Calcd for
C38H48O14: C, 62.63; H, 6.64. Found: C, 62.27; H, 6.38.
4.1.14. Compound 8. To a solution of 28 (0.17 g,
0.23 mmol) in dichloromethane (5 mL) was added oxalyl
chloride (0.2 mL). After stirring for 0.5 h at room
temperature, the solution was concentrated in vacuo to
afford 29 as an oil, which was used directly for next step. To
4.1.11. 2-Bromo-4-[2-[2-[2-(2-bromo-ethoxy)-ethoxy]-

X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
8283
4. (a) Conn, M. M.; Rebek, J. Chem. Rev. 1997, 97, 1647.
(b) Zimmerman, S. C.; Corbin, P. S. Struct. Bonding (Berlin)
2000, 96, 63. (c) Brunsveld, L.; Folmer, B. J. B.; Meijer,
E. W.; Sijbesma, R. P. Chem. Rev. 2001, 101, 4071. (d)
Schmuck, C.; Wienand, W. Angew. Chem., Int. Ed. 2001, 40,
4363. (e) Prins, L. J.; Reinhoudt, D. N.; Timmerman, P.
Angew. Chem., Int. Ed. 2001, 40, 2383. (f) Archer, E. A.;
Gong, H.; Krische, M. J. Tetrahedron 2001, 57, 1139. (g)
Cooke, G.; Rotello, V. M. Chem. Soc. Rev. 2002, 31, 275. (h)
Sijbesma, R. P.; Meijer, E. W. Chem. Commun. 2003, 5.
5. (a) Raymo, F. M.; Stoddart, J. F. Chem. Rev. 1999, 99, 1643.
(b) Pease, A. R.; Jeppesen, J. O.; Stoddart, J. F.; Luo, Y.;
Collier, C. P.; Heath, J. R. Acc. Chem. Res. 2001, 34, 433.
(c) Raehm, L.; Hamilton, D. G.; Sanders, J. K. M. Synlett 2002,
1743.
a stirred solution of 21 (0.21 g, 0.49 mmol), NEt3 (0.5 mL)
and DMAP (10 mg) in chloroform (10 mL) was added a
solution of the above 29 in chloroform (5 mL). The mixture
was heated under reflux for 12 h. After work-up, the crude
product was subjected to flash chromatography (EtOAc/
CH2Cl2 1:1) to afford 8 as a yellowish oil (0.10 g, 30%). IR
(cmK1): 3304, 2926, 2855, 2228, 1706, 1610, 1503, 1389,
1
1286, 1136, 855, 803. H NMR (CDCl3): d 0.85 (t, JZ
7.2 Hz, 12H), 1.14–1.25 (m, 48H), 1.41–1.51 (m, 4H), 1.61–
1.70 (m, 4H), 2.25–2.28 (m, 2H), 2.78 (s, 8H), 3.69–3.72
(m, 16H), 3.79–3.82 (m, 8H), 3.95–3.98 (m, 4H), 4.05–4.09
(m, 4H), 6.71 (s, 4H), 6.87 (s, 2H), 8.13 (d, d, J1Z3.6 Hz,
J2Z8.7 Hz, 4H), 8.46–8.51 (m, 4H), 8.99 (s, 2H), 9.63 (s,
2H). MS (ESI): m/z 1545 [MCH]C. Anal. Calcd for
C90H128N8O14: C, 69.92; H, 8.34; N, 7.25. Found: C, 69.49;
H, 8.38; N, 6.94.
6. (a) Hill, D. J.; Mio, M. J.; Prince, R. B.; Hughes, T.; Moore,
J. S. Chem. Rev. 2001, 101, 3893. (b) Bowden, N. B.; Weck,
M.; Choi, I. S.; Whitesides, G. M. Acc. Chem. Res. 2001, 34,
231. (c) Zhao, D.; Moore, J. S. Chem. Commun. 2003, 807.
7. (a) Amabilino, D. B.; Dietrich-Buchecher, C. O.; Livoreil, A.;
4.1.15. Compound 30. This compound was prepared from
21 and 31 by a method analogous to 20. The crude product
was chromatographed (CH2Cl2/MeOH 50:1) to give 30 as a
1
´
´
Perez-Garcıa, L.; Sauvage, J.-P.; Stoddart, J. F. J. Am. Chem.
Soc. 1996, 118, 3905. (b) Hirschberg, J. H. K. K.; Brunsveld,
L.; Ramzi, A.; Vekemans, J. A. J. M.; Sijbesma, R. P.; Meijer,
E. W. Nature 2000, 407, 167. (c) Zhao, X.; Jiang, X.-K.; Shi,
M.; Yu, Y.-H.; Xia, W.; Li, Z.-T. J. Org. Chem. 2001, 66,
7035. (d) Brunsveld, L.; Vekemans, J. A. J. M.; Hirschberg,
J. H. K. K.; Sijbesma, R. P.; Meijer, E. W. Proc. Natl. Acad.
Sci. U.S.A. 2002, 99, 4977. (e) Cary, J. M.; Moore, J. S. Org.
Lett. 2002, 4, 4663. (f) Shao, X.-B.; Jiang, X.-K.; Wang, X.-Z.;
Li, Z.-T.; Zhu, S.-Z. Tetrahedron 2003, 59, 3505. (g) Yang, X.;
Yuan, L.; Yamato, K.; Brown, A. L.; Feng, W.; Furukawa, M.;
Zeng, X. C.; Gong, B. J. Am. Chem. Soc. 2004, 126, 3148.
8. Beijer, F. H.; Sijbesma, R. P.; Kooijman, H.; Spek, A. L.;
Meijer, E. W. J. Am. Chem. Soc. 1998, 120, 6761.
yellow solid (49%). Mp 156–158 8C. H NMR (CDCl3): d
0.84 (t, JZ6.9 Hz, 12H), 1.22–1.54 (m, 52H), 1.63–1.75 (m,
12H), 2.27–2.30 (m, 2H), 2.46 (t, JZ7.2 Hz, 4H), 8.11 (d,
JZ9.0 Hz, 4H), 8.44 (t, JZ8.4 Hz, 4H), 8.65 (s, 4H).
HRMS (MALDI): m/z 991.7435. Calcd for C60H95N8O4
[MCH]C: 991.7476.
Acknowledgements
We thank the Ministry of Science and Technology (No.
G2000078101), the National Natural Science Foundation
(20321202, 20332040, 20372080), and the State Laboratory
of Bioorganic and Natural Products Chemistry of China for
financial support.
´
´
9. For some recent examples, see (a) Gonzalez, J. J.; Gonzalez,
S.; Priego, E. M.; Luo, C.; Guldi, D. M.; de Mendoza, J.;
Martin, N. Chem. Commun. 2001, 163. (b) Rieth, L. R.; Eaton,
R. F.; Coates, G. W. Angew. Chem., Int. Ed. 2001, 40, 2153.
´
(c) Sanchez, L.; Rispens, M. T.; Hummelen, J. C. Angew.
References and notes
Chem., Int. Ed. 2002, 41, 838. (d) Ten Cate, A. T.; Dankers,
P. Y. W.; Kooijman, H.; Spek, A. L.; Sijbesma, R. P.; Meijer,
E. W. J. Am. Chem. Soc. 2003, 125, 6860. (e) Guan, Z.;
Roland, J. T.; Bai, J. Z.; Ma, S. X.; McIntire, T. M.; Nguyen,
M. J. Am. Chem. Soc. 2004, 126, 2058.
1. (a) Voet, D.; Voet, D. J. Biochemistry. 2nd ed.; Wiley: New
York, 1995. (b) Dugas, H. Bioorganic Chemistry. 3rd ed.;
Springer Verlag: Berlin, 1996.
10. For examples of other kinds of self-complementary quadruple
hydrogen bonding motifs, see (a) Lu¨ning, U.; Ku¨hl, C.
Tetrahedron Lett. 1998, 39, 5735. (b) Sessler, J. L.; Wang,
R. Angew. Chem., Int. Ed. 1998, 37, 1726. (c) Corbin,
P. S.; Zimmerman, S. C. J. Am. Chem. Soc. 1998, 120, 9710.
(d) Gong, B.; Yan, Y.; Zeng, H.; Skrzypczak-Jankunn, E.;
Kim, Y. W.; Zhu, J.; Ickes, H. J. Am. Chem. Soc. 1999, 121,
5607. (e) Corbin, P. S.; Lawless, L. J.; Li, Z.-T.; Ma, Y.;
Witmer, M. J.; Zimmerman, S. C. Proc. Natl. Acad. Sci. U.S.A.
2002, 99, 5099.
¨
2. (a) Vogtle, F. Supramolecular Chemistry—An Introduction;
Wiley: Chichester, UK, 1991. (b) Lehn, J.-M. Supramolecular
Chemistry Concepts and Perspectives; VCH: Weinheim, 1995.
(c) Schneider, H.-J.; Yatsimirsky, A. Principles and Methods
in Supramolecular Chemistry; Wiley: New York, 2001.
(d) Steed, J. W.; Atwood, J. L. Supramolecular Chemistry;
Wiley: New York, 2001. (e) Lindoy, L. F.; Atkinson,
I. M. Self-Assembly in Supramolecular Systems; RCS:
Cambridge, 2002.
3. (a) Sauvage, J. P. Transition Metals in Suparamolecular
Chemistry. Wiley, New York, 1999. (b) Lehn, J.-M. Chem.
Eur. J. 1999, 5, 2455. (c) Sanders, J. K. M. Pure Appl. Chem.
2000, 72, 2265. (d) Leininger, S.; Olenyuk, B.; Stang,
P. J. Chem. Rev. 2000, 100, 853. (e) Holliday, B. J.; Mirkin,
C. A. Angew. Chem., Int. Ed. 2001, 40, 2022. (f) Dinolfo,
P. H.; Hupp, J. T. Chem. Mater. 2001, 13, 3113. (g) Sun,
W.-Y.; Yoshizawa, M.; Kusukawa, T.; Fujita, M. Curr. Opin.
Chem. Biol. 2002, 6, 757. (h) Jiang, H.; Lin, W. J. Am. Chem.
Soc. 2003, 125, 8084.
11. Li, X.-Q.; Jiang, X.-K.; Wang, X.-Z.; Li, Z.-T. Tetrahedron
2004, 60, 2063.
12. Zhao, X.; Wang, X.-Z.; Jiang, X.-K.; Chen, Y.-Q.; Li, Z.-T.;
Chen, G.-J. J. Am. Chem. Soc. 2003, 125, 15128.
13. Wang, X.-Z.; Li, X.-Q.; Shao, X.-B.; Zhao, X.; Deng, P.; Jiang,
X.-K.; Li, Z.-T.; Chen, Y.-Q. Chem. Eur. J. 2003, 9, 2904.
14. For representative examples of quadruple hydrogen bonding
heterodimers, see: (a) Corbin, P. S.; Zimmerman, S. C.;
Thiessen, P. A.; Hawryluk, N. A.; Murray, T. J. J. Am. Chem.

8284
X.-Q. Li et al. / Tetrahedron 60 (2004) 8275–8284
Soc. 2001, 123, 10475. (b) Brammer, L. S.; Lu¨ning, U.; Ku¨hl,
C. Eur. J. Org. Chem. 2002, 4054. (c) Zeng, H.; Yang, X.;
Flowers, R. A.; Gong, B. J. Am. Chem. Soc. 2002, 124, 2903.
17. Hamilton, D. G.; Montalti, M.; Prodi, L.; Fontani, M.; Zanello,
P.; Sanders, J. K. M. Chem. Eur. J. 2000, 6, 608.
18. (a) Sijbesma, R. P.; Beijer, F. H.; Brunsveld, L.; Folmer,
B. J. B.; Hirschberg, J. H. K. K.; Lange, R. F. M.; Lowe,
15. For recent examples of supramolecular self-assembly based on
this interaction, see: (a) Hamilton, D. G.; Davies, J. E.; Prodi,
L.; Sanders, J. K. M. Chem. Eur. J. 1998, 4, 608. (b) Hansen,
J. G.; Feeder, N.; Hamilton, D. G.; Gunter, M. J.; Becher, J.;
Sanders, J. K. M. Org. Lett. 2000, 2, 449. (c) Gabriel,
G. J.; Iverson, B. L. J. Am. Chem. Soc. 2002, 124, 15174. (d)
Shao, X.-B.; Wang, X.-Z.; Jiang, X.-K.; Li, Z.-T.; Zhu, S.-Z.
Tetrehedron 2003, 59, 4881. (e) Zhou, Q.-Z.; Jiang, X.-K.;
Shao, X.-B.; Chen, G.-J.; Jia, M.-X.; Li, Z.-T. Org. Lett. 2003,
5, 1955.
¨
J. K. L.; Meijer, E. W. Science 1997, 278, 1601. (b) Sontjens,
S. H. M.; Sijbesma, R. P.; van Genderen, M. H. P.; Meijer,
E. W. Macrocycles 2001, 34, 3815. (c) Folmer, B. J. B.;
Sijbesma, R. P.; Meijer, E. W. J. Am. Chem. Soc. 2001, 123,
2093.
19. Gitis, L. J. Org. Chem. USSR 1966, 2, 1261.
20. Kheifets, G. M.; Martyushina, N. V.; Mikhailova, T. A.;
Khromov-Borisov, N. V. J. Org. Chem. USSR 1977, 13, 1159.
21. Mills, O. S.; Mooney, N. J.; Robinson, P. M.; Watt,
C. I. F.; Box, B. G. J. Chem. Soc., Perkin Trans. 2 1995, 697.
16. Shao, X.-B.; Wang, X.-Z.; Jiang, X.-K.; Li, Z.-T.; Zhu, S.-Z.
Tetrehedron 2003, 59, 4881.