Molecules with new topologies derived from hydrogen-bonded dimers of tetraurea calix[4]arenes

Article abstract of DOI:10.1002/chem.200801268

Tetraurea calix[4]arenes 2 have been synthesized in which two adjacent aryl urea residues are connected to a loop by an aliphatic chain -O-(CH ₂)_n-O-. The remaining urea residues have a bulky 3,5-di-tert-butylphenyl residue and an ω-alkenyloxyphenyl residue. Since this bulky residue cannot pass through the loop, only one homodimer (2·2) is formed in apolar solvents, for steric reasons, in which the two alkenyl residues penetrate the two macrocyclic loops. Covalent connection of these alkenyl groups by olefin metathesis followed by hydrogenation creates compounds 3, which consist of molecules with hitherto unknown topology. Their molecular structure was confirmed by ¹HNMR spectroscopy and ESIMS, and for one example by single-crystal X-ray analysis.

Full text of DOI:10.1002/chem.200801268

DOI: 10.1002/chem.200801268
Molecules with New Topologies Derived from Hydrogen-Bonded Dimers of
Tetraurea Calix[4]arenes
Anca Bogdan,[a] Michael Bolte,*[b] and Volker Bçhmer*[a]
Abstract: Tetraurea calix[4]arenes
2
dimer (2·2) is formed in apolar sol-
vents, for steric reasons, in which the
two alkenyl residues penetrate the two
macrocyclic loops. Covalent connection
of these alkenyl groups by olefin meta-
thesis followed by hydrogenation cre-
ates compounds 3, which consist of
molecules with hitherto unknown top-
ology. Their molecular structure was
confirmed by 1H NMR spectroscopy
and ESIMS, and for one example by
single-crystal X-ray analysis.
have been synthesized in which two ad-
jacent aryl urea residues are connected
to a loop by an aliphatic chain -O-
(CH2)n-O-. The remaining urea resi-
dues have a bulky 3,5-di-tert-butylphen-
yl residue and an w-alkenyloxyphenyl
residue. Since this bulky residue cannot
pass through the loop, only one homo-
Keywords: calixarenes · dimers ·
knots · macrocycles · topology
Introduction
for shorter loops.[8] The exclusive heterodimerization of bis-
or tetraloop tetraureas with tetra- or octaalkenyl ureas was
successfully used to prepare bis[2]catenanes,[9] bis[3]cate-
nanes, or even cyclic[8]catenanes.[10]
The preparation of topologically nontrivial molecules is pri-
marily an intellectual challenge.[1] Their controlled synthesis
usually requires a suitable prearrangement of the molecular
building blocks to ensure their correct covalent connec-
tion.[2] The dimerization of calix[4]arenes substituted with
four urea residues at the wide rim[3,4] may be used to ar-
range functional groups attached to these urea residues in
well-defined positions.[5] In this way controlled intramolecu-
lar reactions between these functions are possible.
Alternatively, bis[2]catenanes can be prepared by meta-
thesis of homodimers formed by bisalkenyl monoloop ureas
1
(Figure 1).[9] Starting with
a monoloop (n=8; see
Scheme 1 for n and p nomenclature) bisalkenyl (p=6) com-
pound it was possible to synthesize a bis[2]catenane in
which two loops of different sizes were attached to each cal-
ix[4]arene, whereas for longer alkenyl residues (p=9) a
pure compound could not be isolated from the reaction mix-
ture, although the reaction product clearly had the expected
molar mass according to ESIMS.
We obtained multimacrocyclic molecules from heterodi-
mers with a tetratosyl urea group through a metathesis reac-
G
tion between the alkenyl groups (followed by hydrogenation
of the double bonds).[6,7] Fourfold [2]rotaxanes are formed
[a] Dr. A. Bogdan, Dr. V. Bçhmer
Abteilung Lehramt Chemie, Fachbereich Chemie
Pharmazie und Geowissenschaften, Johannes Gutenberg-Universität
Mainz
Duesbergweg 10–14, 55099, Mainz (Germany)
Fax : (+49)613-1392-5419
E-mail: vboehmer@mail.uni-mainz.de
[b] Dr. M. Bolte
Institut für Anorganische Chemie
J.-W.-Goethe-Universität Frankfurt
Marie-Curie-Straße 11
60439 Frankfurt/Main (Germany
Fax : (+49)697-982-9239
E-mail: bolte@chemie.uni-frankfurt.de
Figure 1. Synthesis of bis[2]catenanes by metathesis of homodimers 1·1
(2”a connections). Possible side reactions through b and subsequent b’
connections are also shown.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200801268.
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FULL PAPER
To obtain bis[2]catenanes, alkenyl groups attached to the
same calixarene must be connected by the metathesis reac-
tion (a connections). In principle, connections between al-
kenyl groups attached to different calixarenes are also possi-
ble (b connections), at least when these groups are in adja-
cent positions in the dimer.[11] Such a b connection would
leave two “isolated” alkenyl groups that could be connected
in a second step to form a product isomeric to the expected
bis[2]catenane (Figure 1). Since the separation of these iso-
mers can be difficult, we were primarily interested to see if
the connection of remote alkenyl residues within the dimer
(b’ connection) is possible at all.
by the splitting of signals after addition of Pirkles reagent. It
is worth noting that the dimerization of 2 can occur stereo-
selectively only between molecules of the same enantiomer.
Hence, the dimer has “structurally” C2 symmetry, which is
reduced to C1 symmetry by the directionality of the hydro-
gen-bonded belt.[15]
1H NMR spectra in CDCl3 or [D6]benzene are in agree-
ment with the formation of a single dimer 2·2 with C1 sym-
metry. They show for instance (in 2d for example) eight sig-
nals for the NHa protons at d=10.06–9.90 ppm (two are
overlapped), eight doublets with meta coupling in the d=
6.41–6.24 ppm region, which have the corresponding signals
at d=8.25–8.0 ppm (eight signals were found in the Cosy
spectra, but four of them are overlapped). The aromatic
protons of the bulky residue appear as two doublets (d=
8.33 and 8.26 ppm) and two broad triplets (d=7.29 and
7.23 ppm). Also the two singlets for tert-butyl groups at d=
1.35 and 1.32 ppm demonstrate that the two 3,5-di-tert-butyl-
phenyl residues are different in the C1-symmetrical dimer.[16]
Olefin metathesis with dimers 2·2 followed by hydrogena-
tion led to a single reaction product, 3b,d in the case of
2b,d, which was isolated in 40 and 57% yield, respectively,
after the usual chromatographic work up. The yield drops to
15–20% for compounds 3a,b with the shorter loop and the
crude product contains several byproducts. In the case of
3b,d, ESI mass spectra were measured for samples dissolved
in chloroform/methanol (2:1) and peaks corresponding to
[M+2Na]2+ (3b) and [M+H+Na]2+ (3d) were observed
with the highest (99–100%) abundance. For compounds
3a,c, samples prepared in a similar way gave spectra in
which the peaks could not be interpreted. Clear ESI mass
spectra were obtained, however, when the samples were dis-
solved in chloroform and tetraethylammonium tetrafluoro-
borate was added. In these cases only the peaks correspond-
ing to [M+Et4N]+ were found with 100% abundance.[17] At
this point it is important to notice that the encapsulation of
the cation took place in minutes and no peak corresponding
to a solvent containing capsule was detected.
Results and Discussion
To check, if alkenyl groups of different calixarenes can be
covalently linked by metathesis within a dimer when they
are not in adjacent positions, we prepared monoloop com-
pounds 2 with one alkenyl urea (of different lengths) and
one bulky urea residue (Figure 2). These compounds should
Figure 2. Dimerization of tetraurea 2 and metathesis reaction (followed
by hydrogenation) of the alkenyl residues within the dimer 2·2 (=b’ con-
nection).
form only one homodimer because, for steric reasons, the
loops cannot overlap and the bulky residue cannot penetrate
the loop.[12] Thus, if an intramolecular metathesis reaction is
possible for such a dimer, the product 3 must contain the
discussed b’ connection.
1H NMR spectra (Figure 3) reveal the expected C1 sym-
metry (no symmetry element), showing for instance eight
low-field signals for NHa of the urea groups and eight pairs
of m-coupled doublets for the aromatic protons of the calix-
arene parts, which are completely resolved for the low-field
part.
Compounds 2 were synthesized in four steps starting with
the bis-BOC protected tetraamine 4,[13] as shown in
Scheme 1: Cyclization with an activated bisurethane[14]
under dilution led to the formation of macrocyclic diureas
(60–80%), which were quantitatively deprotected. Diamines
5a,b were first monoacylated with the activated urethane 7a
to introduce the bulky urea residue (47–52% of 6a,b). Fi-
nally the alkenyl urea residue was introduced analogously
by acylation with 7b,c in the last step to give 2b,d in 60–
80% yield. Alternatively, the alkenyl group was introduced
first by acylation of 5a,b with active ester 7b (44–59% of
6c,d) followed by acylation with 7a in the second step to
give 2a,c in yields of 58–80%. No clear advantage was
found for one of these two possible pathways.
All these results prove that the envisaged b’ connection
was in fact achieved in all cases.
Many early attempts to confirm the complicated connec-
tivities in compounds 3 by crystallography failed. Although
several single crystals were grown from 3d, it was impossible
to solve their structure by X-ray analysis. Since heavy atoms
often facilitate the determination of the structure, we started
the synthesis of compound(s) in which bromine atoms re-
place the tert-butyl groups as the bulky residues. Unfortu-
nately the bromine atoms are too small to ensure a selective
dimerization, at least in combination with a loop of n=10.
After a crystal structure was eventually obtained for 3d
these studies were not continued.
The structure of compounds 2 was confirmed by ESIMS
1
and H NMR spectroscopy in [D6]DMSO or [D8]THF. Since
the molecules are fixed in the cone conformation, they are
chiral (C1 symmetry) and this chirality can be demonstrated
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V. Bçhmer, M. Bolte, and A. Bogdan
Scheme 1. Synthesis of monoloop compounds 2a–d.
Crystal structure: After numerous attempts with various
crystals the structure of 3d could be finally solved. Crystals
were obtained by slow evaporation of a solution in chloro-
form/acetonitrile. Two crystallographically independent mol-
ecules (I, II) were found, in which both calixarene parts
form a hydrogen-bonded capsule. They differ mainly by the
conformation of the aliphatic (CH2)10 chains connecting two
adjacent phenylurea groups (a, b) within each calixarene
part (A ,B) and the (CH2)20 chain connecting the two calix-
arene parts (via c). The capsule includes two acetonitrile
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Hydrogen-Bonded Dimers of Tetraurea Calix[4]arenes
FULL PAPER
Table 1. Comparison of some characteristic crystallographic data.
Dimer
I[a]
II[a]
Tetraester[18]
planes of calix O atoms
distance between centers [Š]
angle [8]
12.819
7.49.5
12.818
0.0
12.487
planes of methylene C atoms
distance between centers [Š]
angle [8]
10.226
3.2
10.217
5.5
9.784
0.0
1
planes of carbonyl C atoms
distance between centers [Š]
angle [8]
Figure 3. Sections of the H NMR-spectrum of 3b in C6D6. Top: aryl NH.
1.422
1.42.9
1.375
0.0
1.100
*
Bottom: calix NH protons ( ), aromatic protons of the calixarene skele-
ton ( ), and aromatic protons of the 3,5-di-tert-butylphenyl groups (*)
*
are indicated and the rest of the signals are the meta-substituted phenolic
rings of the loops.
calixarene A[b]
À
O O distance diagonal [Š]
4.944
3.963
5.025
3.855
58.6[c]
72.1[c]
4.376
62.4
angle calix-phenyl plane/
reference plane [8]
64.9[c]
57.1[c]
63.469.8
70.8[d]
molecules in a roughly antiparallel orientation. Five chloro-
form and five acetonitrile molecules are additionally incor-
porated into the crystal lattice. The molecular conformation
of molecule I is shown in Figure 4a and the packing of mole-
cules I and II is shown in Figure 4b.
56.0[d]
calixarene B[b]
À
O O distance diagonal [Š]
4.951
3.878
62.0[c]
70.9[c]
68.5
4.899
4.211
66.5[c]
67.5[c]
68.0
4.469
64.1
angle calix-phenyl plane/
reference plane [8]
54.2[d]
56.8[d]
[a] Two crystallographically independent molecules. [b] Two calixarene
parts per molecule. [c] Adjacent phenyl rings connected by the loop.
[d] Phenyl ring with the voluminous residue.
ference of both capsules is indicated by the interplanar
angle for the best planes through the phenolic oxygen atoms
(7.4and 9.5 8) and the carbon atoms of the methylene
bridges (3.2/5.58), whereas the cyclic belt of hydrogen bonds
requires nearly parallel planes (1.4/2.98) for the carbonyl
carbons.
The distortion of the single calix[4]arenes may be charac-
terized by the diagonal distances of the phenolic oxygen
atoms, which differ by 0.981 and 1.073 Š for both calixar-
enes forming capsule I and by 1.17 and 0.688 Š for those of
II. They are also indicated by the inclination angles of the
aromatic planes of the calixarene, which range from 54.2 to
72.18. However, these slight distortions are not (necessarily)
caused by the aliphatic chains within and between the cal-
ix[4]arenes, which contain many anti and gauche conforma-
tions characteristic for an unstrained aliphatic chain.
The crystal structure reveals a rather “relaxed” situation
despite the different phenyl substituents attached to the
four urea groups. Probably the difference of the four phe-
nolic units is not pronounced enough, to entirely prevent
the incorporation of the molecules under (slightly) different
orientations in the crystal lattice. Such a disorder, obtained
for instance by rotation around the axis of the dimeric cap-
sule, would explain the difficulties in solving the structure
that we initially faced.
Figure 4. a) Molecular conformation of 3d (molecule I) seen from the
top (left) and from the side (right). Hydrogen atoms are omitted for
clarity. Loops connecting adjacent urea groups within a calixarene are
green and blue; the chain connecting the two calixarenes is yellow.
b) Packing of 3d in the crystal lattice, as seen along the a axis. The two
crystallographically independent molecules are indicated by I and II.
The first crystal structure described for a hydrogen-
bonded dimer of a tetraurea calix[4]arene[18] shows a mole-
cule with a fourfold axis.[19] Such a fourfold symmetry is im-
possible for the present molecule 3d, but the shape of the
capsules itself, without the connecting aliphatic chains is
rather similar, as shown by the values compared in
Table 1.[20] The distance between the centers of the two ref-
erence planes defined by the carbon atoms of the calixarene
methylene bridges is nearly identical for I and II (10.226/
10.217 Š), but significantly larger (by 0.438 Š) than in the
tetraester capsule.[18] A significant distortion and a slight dif-
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V. Bçhmer, M. Bolte, and A. Bogdan
General procedure for the synthesis of the compound 2: A solution of 6 in
THF, the corresponding active urethane 7 (in a molar ratio of 1:1) and
diisopropylethylamine (1 mL) was heated at reflux for 12 h. The reaction
mixture was diluted with dichloromethane and washed with a solution of
K2CO3 until the water phase remained colorless. After drying over
MgSO4, the solvent was evaporated and the product was crystallized
from chloroform/methanol. If the product was not yet pure it was further
purified by column chromatography (THF or ethyl acetate/hexane mix-
ture as the eluent).
Conclusion
Molecules 3 show an interesting and, to the best of our
knowledge, unprecedented topology that can be explained
by the “transformations” shown in Figure 5.
First the nonconnected urea arms can be omitted and the
calixarene macrocycles may be reduced to a point because
they are not involved in catenation. Further deformations fi-
nally lead to a topological representation that may be de-
1
2a: Yield=58%; H NMR ([D6]DMSO, 400 MHz, 258C): d=8.34(s, 1H;
NH), 8.26 (s, 1H; NH), 8.23 (s, 1H; NH), 8.22 (s, 1H; NH), 8.12 (s, 1H;
NH), 8.07 (s, 1H; NH), 8.02 (s, 1H; NH), 8.01 (s, 1H; NH), 7.17 (brt,
1H; Armeta-H), 7.12 (brd, 2H; Ar-H), 7.09 (brt, 1H; Armeta-H), 7.03 (d,
1H; 4Jꢀ1.5 Hz, Arcalix-H), 7.00–6.96 (3 m, 3H; Armeta-H), 6.90 (m, 2H;
Arcalix-H+Ar-H), 6.84(brs, 1H; Ar calix-H), 6.76 (brs, 1H; Arcalix-H), 6.73
(brs, 1H; Arcalix-H), 6.67 (dd, 1H; 3J=8.2 Hz, 4Jꢀ1.0 Hz, Armeta-H),
6.48–6.45 (m, 4H; 2Arcalix-H+2Armeta-H), 6.42–6.38 (m, 5H; Arcalix-H+
4Armeta-H), 5.74–5.67 (m, 1H, =C-H), 4.93–4.83 (m, 2H, =C-H2), 4.27
(d, 4H; 2J=11.44 Hz, Ar-CH2-Arax), 3.85–3.72 (m, 12H; -OCH2), 3.08–
3.00 (m, 4H; Ar-CH2-Areq), 1.93 (m, 2H; -CH2-), 1.83 (m, 10H; -CH2-),
1.59 (m, 4H; -CH2-), 1.36–1.30 (m, 16H; -CH2-), 1.26–1.24(m, 4H; -C H2-
), 1.16(s, 18H; tBu) 0.87 ppm (t, 3J=5.6 Hz, 12H; -CH3); ESIMS: m/z
(%): 1645.01 (100) [M+Na]+.
Figure 5. Illustration of the topology of molecules 3 by graphical simplifi-
cations: a) omission of the bulky “open ended” urea residue;
b) “shrinkage” of the calixarene to a point; and c) graphical rearrange-
ment.
2b: Yield=58%; 1H NMR ([D6]benzene, 400 MHz, 608C): d=9.92 (s,
1H; NH), 9.88 (s, 1H; NH), 9.86 (s, 3H; NH), 9.84(s, 1H; N H), 9.72 (s,
2H; NH), 9.69 (s, 2H; NH), 8.39 (brs, 2H; Armeta-H), 8.23 (brd, 2H; Ar-
H), 8.23–8.21 (m, 2H; Armeta-H), 8.19 (m, 3H; Ar-H+Arcalix-H+Arcalix
-
H), 8.11 (brt, 1H; Armeta-H), 8.09 (d, 4J=1.8 Hz, 1H; Arcalix-H), 8.05
(brt, 1H; Armeta-H), 8.03 (d, 4J=2.6 Hz, 1H; Arcalix-H), 8.02 (d, 4J=
2.6 Hz, 1H; Arcalix-H), 7.96 (brs, 2H; Arcalix-H), 7.92 (d, 4J=1.8 Hz, 1H;
Arcalix-H), 7.61 (m, 2H; Armeta-H+Armeta-H), 7.55 (brt, 1H; Armeta-H),
scribed as follows: Two rings with an attached axle form a
“double” rotaxane by mutual penetration. Additionally the
open ends of the axles are connected to a macrocycle. Thus,
the molecule combines structural elements of rotaxanes and
catenanes and shows in addition some similarities to knots.
To the best of our knowledge, such a topology has not yet
been described and synthetically realized.
3
7.53 (s, 1H; NH), 7.49 and 7.47 (brdd, J=8.1 Hz, 1H; Armeta-H), 7.46 (s,
1H; NH), 7.36 (m, 2H; Armeta-H), 7.29 (brs, 1H; Ar-H), 7.27 (s, 1H;
NH), 7.24(brs, 1H; Ar- H), 7.24(m, 2H; Ar meta-H+NH), 7.22 (t, 3J=
8.2 Hz, 1H; Armeta-H), 7.07 (t, 3J=7.8 Hz, 1H; Armeta-H), 7.03 (t, 1H;
3J=8.2 Hz, Armeta-H), 6.75–6.69 (m, 4H; 2Armeta-H+2NH), 6.62–6.55
(m, 5H; 4Armeta-H+NH), 6.39 (d, 4J=2.0 Hz, 1H; Arcalix-H), 6.33 (m,
4
2H; Arcalix-H), 6.31 (d, J=2.0 Hz, 1H; Arcalix-H), 6.29 (m, 2H; Arcalix-H),
6.19 (d, 4J=2.0 Hz, 1H; Arcalix-H), 6.04(d, 4J=2.0 Hz, 1H; Arcalix-H),
5.85–5.75 (m, 2H; =C-H), 5.05–4.95 (m, 4H; =C-H2), 4.63 (d, 2J=
12.0 Hz, 1H; Ar-CH2-Arax), 4.57 (d, 2J=12.0 Hz, 2H; Ar-CH2-Arax), 4.55
(d, 2J=10.6 Hz, 1H; Ar-CH2-Arax), 4.53 (d, 2J=12.3 Hz, 1H; Ar-CH2-
Arax), 4.48 (d, 2J=11.2 Hz, 1H; Ar-CH2-Arax), 4.46 (d, 2J=11.7 Hz, 1H;
Ar-CH2-Arax), 4.45 (d, 2J=10.9 Hz, 1H; Ar-CH2-Arax), 4.25–3.10 (2”m,
4H; -OCH2), 3.9–3.75 (m, 24H; -OCH2), 3.30 (d, 2J=11.7 Hz, 1H; Ar-
CH2-Areq), 3.25 (d, 2J=11.7 Hz, 1H; Ar-CH2-Areq), 3.24(d, 2J=11.7 Hz,
1H; Ar-CH2-Areq), 3.22 (d, 2J=12.0 Hz, 1H; Ar-CH2-Areq), 3.15 (d, 2J=
11.7 Hz, 1H; Ar-CH2-Areq), 3.13 (d, 2J=11.7 Hz, 1H; Ar-CH2-Areq), 3.06
(d, 2J=12.0 Hz, 1H; Ar-CH2-Areq), 3.01 (d, 2J=12.3 Hz, 1H; Ar-CH2-
Areq), 2.1–1.2 (5”m, 106H; -CH2-), 1.36 (s, 18H; tBu), 1.34(s, 18H;
tBu), 1.0–0.91 ppm (m, 24H; -CH3).
Experimental Section
General: DMF (peptide synthesis grade) was purchased from Acros, the
Grubbs catalyst (first generation) from Strem and deuterated solvents
from Deutero GmbH. All reactions were carried out under nitrogen.
Column chromatography was performed with silica gel (Merck, 0.040–
0.063 mm). 1H and 13C NMR spectra were recorded on
a Bruker
DRX400 Avance Instrument at 400 and 100.6 MHz, respectively. Chemi-
cal shifts were calibrated to the residual signal of the deuterated solvent.
Mass spectra were obtained on a Finnigan MAT 8230 spectrometer.
Syntheses: Compounds 4,[12] 5, and 7b,c were prepared as described pre-
viously.[19] The active urethane 7d was synthesized in three steps and is
reported in the Supporting Information. For compounds 6, 2, and 3, rep-
resentative examples are described herein, together with 1H NMR and
MS data. The remaining compounds and all 13C NMR data are included
in the Supporting Information.
2c: Yield=80%; ESIMS: m/z (%): 1673.16 (100) [M+Na]+.
2d: Yield=60%; ESIMS: m/z (%): 1715.04(100) [ M+Na]+, 1693.07 (46)
[M+H+].
General procedure for the synthesis of 3: A 0.5 mmol solution of 2 in ben-
zene was heated at 608C for 2–6 h and the formation of the homodimer
was confirmed by NMR spectroscopy measurements. After cooling at
room temperature the reaction mixture was purged with nitrogen for
30 min and a solution of the Grubbs catalyst (0.15 mmol/double bond) in
benzene (5 mL) was added in one portion. The reaction mixture was
stirred at room temperature for two days. The catalyst was destroyed by
adding triethylamine (1 mL) and additional stirring for 30 min. The reac-
tion mixture was concentrated at low pressure and hydrogenated in the
presence of platinum dioxide. After filtration and evaporation the crude
product was purified by column chromatography (THF/hexane mixture
as the eluent). The pure compound was obtained after crystallization
from THF/methanol.
General procedure for the synthesis of the compound 6: A solution of
active urethane 7 (0.84mmol) in DMF (peptide synthesis grade, 25 mL)
was added dropwise (5 mLhÀ1) to a solution of diamine 5 (0.7 mmol) and
diisopropylethylamine (1 mL) in DMF (200 mL). The reaction mixture
was stirred for an additional hour and then the solvent was evaporated.
The dry residue was dissolved in dichloromethane and washed with a so-
lution of K2CO3 until the water phase remained colorless. After drying
over MgSO4, the solvent was evaporated and the product was purified by
column chromatography (silica gel, THF or ethyl acetate/hexane mixture
as the eluent). The product was used in the next step after being analyzed
by MS.
6a: Yield=52%; ESIMS: m/z (%): 1398.9 (100) [M+Na]+.
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Hydrogen-Bonded Dimers of Tetraurea Calix[4]arenes
FULL PAPER
3a: M.p.>2708C decomposition without melting; yield=18%; 1H NMR
([D6]benzene, 400 MHz, 25 and 608C): very broad and insignificant;
ESIMS (complex with (C2H5)4N+PF6À): m/z (%): 3348.61 (100)
[M+Et4N]+.
40.4609(10) Š;
a=77.373(2),
b=88.180(2),
g=72.699(2)o;
V=
21755.2(8) Š3; Z=4; colorless block-shaped crystal; STOE-IPDS-II two-
circle diffractometer; T=173 K; MoKa radiation; 2q range=2.82–51.38o;
416706 reflections collected; 81625 independent reflections (Rint
=
0.0949); empirical absorption correction (MULABS);[21] structure solu-
3b: M.p.>2508C decomposition without melting; yield=57%; 1H NMR
([D6]benzene, 400 MHz, 258C): d=10.14(s, 1H; N H), 10.12 (s, 1H; NH),
10.08 (s, 1H; NH), 10.03 (s, 1H; NH), 10.02 (s, 1H; NH), 9.98 (s, 1H;
NH), 9.92 (s, 2H; NH), 8.52 (brs, 3H; Armeta-H), 8.36 and 8.34(brdd,
3J=8.2 Hz, 2H; Armeta-H), 8.33 (d, 4J=1.6 Hz, 2H; Ar-H), 8.33 and 8.31
(brdd, 3J=8.2 Hz, 2H; Armeta-H), 8.33 and 8.31 (brdd, 3J=8.2, 4J=
1.4Hz, 2H; Ar meta-H), 8.28 and 8.26 (brdd, 2H; 3J=8.2 Hz, 4J=1.4Hz,
tion with SHELXS-90;[22] refinement on F2 with SHELXL-97;[23] R1-
A
restraints of 1.50(1) Š for 1–2 and 2.45(1) Š for 1–3 distances. The disor-
dered aromatic ring was refined with restraints of 1.40(1) Š for 1–2 and
2.45(1) Š for 1–3 distances.
CCDC-689511 contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
4
4
Armeta-H), 8.26 (d, 2H; J=1.6 Hz, Ar-H), 8.23 (d, J=2.3 Hz, 1H; Arcalix
-
4
4
H), 8.19 (d, J=2.5 Hz, 1H; Arcalix-H), 8.15 (d, J=2.5 Hz, 1H; Arcalix-H),
8.13 (d, 4J=2.5 Hz, 1H; Arcalix-H), 8.09 (d, 4J=2.5 Hz, 1H; Arcalix-H),
8.05 (d, 4J=2.3 Hz, 1H; Arcalix-H), 8.03 (d, 4J=2.3 Hz, 1H; Arcalix-H),
7.80 (d, 4J=2.3 Hz, 1H; Arcalix-H), 7.64(t, 4J=1.8 Hz, 1H; Armeta-H),
7.62 (s, 2H; NH), 7.59 (t, 4J=1.7 Hz, 1H; Armeta-H), 7.56 (t, 4J=1.8 Hz,
1H; Armeta-H), 7.50 and 7.48 (brdd, 3J=8.1 Hz, 1H; Armeta-H), 7.48 (s,
1H; NH), 7.39 (t, 3J=8.1 Hz, 1H; Armeta-H), 7.36 (s, 1H; NH), 7.310 (t,
3J=8.1 Hz, 1H; Armeta-H), 7.316 (s, 1H; NH), 7.27 (t, 4J=1.5 Hz, 1H;
Ar-H), 7.27 and 7.25 (brdd, 3J=8.2 Hz, 1H; Armeta-H), 7.23 (t, 4J=
Acknowledgements
Financial support by the Deutsche Forschungsgemeinschaft (Bo 523/14-4,
SFB 625) is gratefully acknowledged.
3
3
1.6 Hz, 1H; Ar-H), 7.12 (t, J=8.2 Hz, 1H; Armeta-H), 7.08 (t, J=6.3 Hz,
3
3
1H; Armeta-H), 7.01 (t, J=8.2 Hz, 1H; Armeta-H), 6.99 (t, J=8.1 Hz, 1H;
Armeta-H), 6.88 (s, 1H; NH), 6.68 and 6.66 (dd, 3J=8.2, 4J=1.8 Hz, 1H;
Armeta-H), 6.78 and 6.76 (dd, 3J=8.4, 4J=1.6 Hz, 1H; Armeta-H), 6.70 (m,
1H; Armeta-H), 6.67 and 6.65 (dd, 3J=8.2, 4Jꢀ2 Hz, 1H; Armeta-H), 6.65
and 6.63 (dd, 3J=8.2, 4Jꢀ2 Hz, 1H; Armeta-H), 6.60 (s, 1H; NH), 6.59
[1] Molecular Catenanes, Rotaxanes, and Knots (Eds.: J.-P. Sauvage, C.
Dietrich-Buchecker), Wiley-VCH, Weinheim, 1999; for a recent ap-
pealing example, see: K. S. Chichak, S. J. Cantrill, A. R. Pease, S. H.
Chiu, G. W. V. Cave, J. L. Atwood, J. F. Stoddart, Science 2004, 304,
1308–1312.
[2] For an actual review on “Templated Synthesis of Interlocked Mole-
cules”, see: F. Aricꢁ, J. D. Badjic, S. J. Cantrill, A. H. Flood, K. C.-F.
Leung, Y. Liu, J. F. Stoddart, Top. Curr. Chem. 2005, 249, 203–259.
[3] For early publications, see: K. D. Shimizu, J. Rebek, Jr., Proc. Natl.
Acad. Sci. USA 1995, 92, 12403–12407; B. C. Hamann, K. D. Shimi-
zu, J. Rebek, Jr., Angew. Chem. 1996, 108, 1425–1427; Angew.
Chem. Int. Ed. Engl. 1996, 35, 1326–1329; O. Mogck, V. Bçhmer,
W. Vogt, Tetrahedron 1996, 52, 8489–8496.
[4] For reviews, see: J. Rebek, Jr., Chem. Commun. 2000, 637–643; V.
Bçhmer, M. O. Vysotsky, Aust. J. Chem. 2001, 54, 671–677.
[5] A. Bogdan, Y. Rudzevich, M. O. Vysotsky, V. Bçhmer, Chem.
Commun. 2006, 2941–2952.
[6] M. O. Vysotsky, A. Bogdan, L. Wang, V. Bçhmer, Chem. Commun.
2004, 1268–1269.
[7] For the heterodimerization of aryl and tosylureas, see: R. K. Castel-
lano, B. H. Kim, J. Rebek, Jr., J. Am. Chem. Soc. 1997, 119, 12671–
12672; R. K. Castellano, J. Rebek, Jr., J. Am. Chem. Soc. 1998, 120,
3657–3663; Y. Rudzevich, M. O. Vysotsky, V. Bçhmer, M. S. Brody,
J. Rebek, Jr., F. Broda, I. Thondorf, Org. Biomol. Chem. 2004, 2,
3080–3084.
[8] O. Molokanova, M. O. Vysotsky, Y. Cao, I. Thondorf, V. Bçhmer,
Angew. Chem. 2006, 118, 8220–8224; Angew. Chem. Int. Ed. 2006,
45, 8051–8055.
[9] M. O. Vysotsky, A. Bogdan, T. Ikai, Y. Okamoto, V. Bçhmer, Chem.
Eur. J. 2004, 10, 3324–3330.
[10] L. Wang, M. O. Vysotsky, A. Bogdan, M. Bolte, V. Bçhmer, Science
2004, 304, 1312–1314.
3
4
4
and 6.57 (dd, J=8.2, J=2.1 Hz, 1H; Armeta-H), 6.41 (d, J=2.5 Hz, 1H;
Arcalix-H), 6.32 (m, 4H; Arcalix-H), 6.24(d, 4J=2.5 Hz, 1H; Arcalix-H), 6.21
(d, 4J=2.3 Hz, 1H; Arcalix-H), 6.01 (d, 4J=2.5 Hz, 1H; Arcalix-H), 4.59–
4.40 (m, 8H; Ar-CH2-Arax), 4.3–3.50 (four m, 28H; -OCH2), 3.28–3.07
(m, 8H; Ar-CH2-Areq), 2.1–1.9 (m, 16H; -CH2-), 1.8–1.7 (m, 6H; -CH2-),
1.5–1.1 (m, 80H; -CH2-), 1.37 (s, 18H; tBu), 1.32 (s, 18H; tBu), 1.0–
0.91 ppm (m, 12H; -CH3); ESIMS: m/z (%): 1674.02 (100) [M+2Na]2+
,
3324.94 (61) [M+Na]+.
3c: M.p.>2708C decomposition without melting; yield=15%; 1H NMR
([D6]benzene, 400 MHz, 25 and 608C): very broad and insignificant;
ESIMS (complex of the molecule with C8H20NPF6): m/z (%): 3404.65
(100) [M+Et4N]+.
3d: M.p.>2658C decomposition without melting; yield=37%; 1H NMR
([D6]benzene, 400 MHz, 258C): d=10.13 (s, 1H; NH), 10.06 (s, 1H; NH),
10.05 (s, 1H; NH), 10.03 (s, 1H; NH), 10.00 (s, 1H; NH), 9.97 (s, 1H;
NH), 9.95 (s, 1H; NH), 9.92 (s, 1H; NH), 8.50 (brs, 2H; Armeta-H), 8.44
(brs, 1H; Armeta-H), 8.38 and 8.36 (brdd, 3J=8.2 Hz, 2H; Armeta-H), 8.30
(d, 4J=1.5 Hz, 2H; Ar-H), 8.26 (d, 4J=1.3 Hz, 2H; Ar-H), 8.26 and 8.24
3
4
(brdd, J=8.2 Hz, 2H; Armeta-H), 8.19 (d, J=2.3 Hz, 1H; Arcalix-H), 8.18
(d, 4J=2.3 Hz, 1H; Arcalix-H), 8.16 (d, J=2.0 Hz, 1H; Arcalix-H), 8.13 (d,
4
4J=2.2 Hz, 1H; Arcalix-H), 8.09 (d, 4J=2.5 Hz, 1H; Arcalix-H), 8.08 (d,
4J=2.5 Hz, 1H; Arcalix-H), 8.06 (d, 4J=2.2 Hz, 1H; Arcalix-H), 7.90 (d,
4J=2.3 Hz, 1H; Arcalix-H), 7.62 (s, 1H; NH), 7.60 (brs, 2H; Armeta-H),
7.57 (m, 2H; NH+Armeta-H), 7.53 (brs, 1H; Armeta-H), 7.50 and 7.48
(brdd, 3J=8.1 Hz, 2H; Armeta-H), 7.40 (s, 1H; NH), 7.38 (t, 3J=8.3 Hz,
1H; Armeta-H), 7.35 (s, 1H; NH), 7.27 (m, 2H; Armeta-H+Ar-H), 7.26 (t,
3J=8.1 Hz, 1H; Armeta-H), 7.23 (m, 2H; NH+Ar-H), 7.11 (t, 3J=8.1 Hz,
1H; Armeta-H), 7.08 (brs, 1H; Armeta-H), 7.05 (s, 1H; NH), 7.04(s, 1H;
[11] This was shown for homodimers of tetraalkenyl tetraureas, which
gave in addition to bis[2]catenanes (2 a connections) doubly bridged
monocatenanes (a and b connection) and tetrabridged dimers (2 b
connections); see M. O. Vysotsky, M. Bolte, I. Thondorf, V. Bçhmer,
Chem. Eur. J. 2003, 9, 3375–3382.
NH), 7.01 (t, 3J=8.2 Hz, 1H; Armeta-H), 6.98 (t, 3J=8.4Hz, 1H; Ar meta
-
H), 6.79 (s, 1H; NH), 6.73–6.71 (m, 3H; Armeta-H), 6.66 and 6.64(dd,
4
3J=8.2, 4J=1.7 Hz, 1H; Armeta-H), 6.57 and 6.55 (dd, 3J=8.2, J=2.0 Hz,
4
1H; Armeta-H), 6.56 and 6.54(dd, 3J=7.9, J=2.0 Hz, 1H; Armeta-H), 6.38
4
4
(d, J=2.0 Hz, 1H; Arcalix-H), 6.35 (d, J=2.3 Hz, 1H; Arcalix-H), 6.32 (m,
4H; Arcalix-H), 6.26 (d, 4J=2.2 Hz, 1H; Arcalix-H), 6.19 (d, 4J=2.2 Hz,
1H; Arcalix-H), 4.54–4.41 (m, 8H; Ar-CH2-Arax), 4.00–3.52 (m, 28H;
-OCH2), 3.36–3.18 (m, 8H; Ar-CH2-Areq), 2.1–1.9 (m, 16H; -CH2-), 1.72–
1.63 (m, 6H; -CH2-), 1.5–0.9 (m, 88H; -CH2-), 1.35 (s, 18H; tBu), 1.31 (s,
18H; tBu), 0.99–0.92 ppm (m, 12H; -CH3); ESIMS: m/z (%): 1691.06
[12] D. Braekers, C. Peters, A. Bogdan, Y. Rudzevich, V. Bçhmer, J. F.
Desreux, J. Org. Chem. 2008, 73, 701–706; Y. Rudzevich, Y. Cao, V.
Rudzevich, V. Bçhmer, Chem. Eur. J. 2008, 14, 3346–3354.
[13] M. Saadioui, A. Shivanyuk, V. Bçhmer, W. Vogt, J. Org. Chem.
1999, 64, 3774–3777.
[14] A. Bogdan, M. O. Vysotsky, T. Ikai, Y. Okamoto, V. Bçhmer, Chem.
Eur. J. 2004, 10, 3324–3330.
[15] A. Pop, M. O. Vysotsky, M. Saadioui, V. Bçhmer, Chem. Commun.
2003, 1124–1125.
(100) [M+H+Na]2+, 1680.07 (99) [M+2H]2+, 1702.06 (30) [M+2Na]2+
X-ray structure analysis: 2(C208H282N16O22)·5CHCl3·5C2H3N; Mr =
.
¯
3759.55; triclinic; space group P1; a=20.2740(4), b=28.4843(6), c=
Chem. Eur. J. 2008, 14, 8514– 8520
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8519

V. Bçhmer, M. Bolte, and A. Bogdan
[16] The two tert-butyl groups in the 3,5-position are identical due to fast
Thondorf, V. Bçhmer, V. Rudzevich, Y. Rudzevich, CrystEngComm
2008, 10, 270–272.
À
rotation around the aryl N bond.
[17] Despite their size, tetraethylammonium cations are preferentially in-
cluded as guest; for an X-ray structure, see: I. Thondorf, F. Broda,
K. Rissanen, M. Vysotsky, V. Bçhmer, J. Chem. Soc. Perkin Trans. 2
2002, 1796–1800; this inclusion has been used for the mass spectro-
scopic analysis of dimeric capsules, see: C. A. Schalley, R. K. Castel-
lano, M. S. Brody, D. M. Rudkevich, G. Siuzdak, J. Rebek, Jr., J.
Am. Chem. Soc. 1999, 121, 4568–4579.
[20] These values are the average for two crystallographically independ-
ent molecules present also in the former structure.
[21] R. H. Blessing, Acta Crystallogr. Sect. A 1995, 51, 33–38.
[22] G. M. Sheldrick, Acta Crystallogr. Sect. A 1990, 46, 467–473.
[23] G. M. Sheldrick, SHELXL-97, A Program for the Refinement of
Crystal Structures, University of Gçttingen, Gçttingen (Germany),
1997.
[18] O. Mogck, E. F. Paulus, V. Bçhmer, I. Thondorf, W. Vogt, Chem.
Commun. 1996, 2533–2534.
Received: June 25, 2008
Published online: August 21, 2008
[19] For further crystal structures of tetraurea dimers, see ref. [11] and O.
Molokanova, A. Bogdan, M. O. Vysotsky, M. Bolte, T. Ikai, Y. Oka-
moto, V. Bçhmer, Chem. Eur. J. 2007, 13, 6157–6170; M. Bolte, I.
Please note: Minor changes have been made to Scheme 1 in this publica-
tion in Chemistry—A European Journal Early View. The Editor.
8520
www.chemeurj.org
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2008, 14, 8514– 8520