Analysis and improvement of an anion-templated rotaxane synthesis

Article abstract of DOI:10.1002/1522-2675(200206)85:6<1578::AID-HLCA1578>3.0.CO;2-L

A series of new rotaxanes with axles different in length was prepared. Following the synthetic protocol utilizing a known anion template effect (Scheme 1), surprisingly low yields in the order of 2 - 5% were obtained (Scheme 3), which furthermore signific

Full text of DOI:10.1002/1522-2675(200206)85:6<1578::AID-HLCA1578>3.0.CO;2-L

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Helvetica Chimica Acta Vol. 85 (2002)
Analysis and Improvement of an Anion-Templated Rotaxane Synthesis
by Christoph A. Schalley*, Gabriele Silva, Carl Friedrich Nising, and Petra Linnartz
¬
Kekule-Institut f¸r Organische Chemie und Biochemie der Universit‰t Bonn, Gerhard-Domagk-Str. 1,
D-53121 Bonn (e-mail: c.schalley@uni-bonn.de)
A series of new rotaxanes with axles different in length was prepared. Following the synthetic protocol
utilizing a known anion template effect (Scheme 1), surprisingly low yields in the order of 2 5% were obtained
(Scheme 3), which furthermore significantly depended on the nature of the stopper (Fig. 1). Variations in the
synthetic procedures and computational results from Monte Carlo simulations allowed us to analyze the origin
of these findings: The rotaxane wheel 3 acts as a noncovalently bound −protecting group× for the stopper
nucleophile. The protection of the nucleophilic phenolate O-atom depends much on the steric demands of the
stoppers (see 2 vs. 10) which induce different conformations of the wheel. Based on this model, an improved
synthetic scheme is suggested.
1. Introduction.
The synthesis of rotaxanes, catenanes, and other types of
mechanically interlocked molecules [1] strongly relies on the operation of efficient
template effects [2]. There exist different apparoches including inter alia those based on
the tetrahedral [3] or octahedral [4] coordination geometry of metal ions, p-donor/p-
acceptor interactions [5], and H-bonding involving ammoniums ions [6] or neutral
amides [7]. The latter is believed to play a crucial role in the formation of a trefoil knot
with twelve amide bonds [8]. Recently, Vˆgtle and co-workers reported [9] the high-
yield rotaxane synthesis shown in Scheme 1, which is based on the recognition of
phenolate stopper 2À within the macrocyclic rotaxane wheel 3. Two H-bonds bind the
trityl phenolate with a surprisingly high binding constant of K > 105 mÀ1 [9][10] so that
the equilibrium is shifted far to the side of the stopper-wheel complex 2À ¥ 3. If the axle-
center piece 1 is added to the reaction mixture, the semi-axle 4 is formed either in a
direct reaction of 1 with free 2À, or in a reaction of 1 and 2À ¥ 3 followed by deslipping
that occurs due to the much lower strength of the H-bonds formed between the wheel
and the semi-axle ether O-atom. Finally, the semi-axle 4 reacts with 2À ¥ 3 to yield the
rotaxane 5 ¥ 3 in up to 95% yield.
For deslipping experiments [11], we attempted to synthesize rotaxanes with axle-
center pieces of different lengths, i.e., 9a j (obtained from 6 and 7a j via 8a j, see
Scheme 2), and stoppers of intermediate size such as 10 (Scheme 3). Surprisingly, the
rotaxane yields decreased dramatically for the rotaxanes discussed here, even to below
5%. Instead, large amounts of the free axle were isolated as the by-product. Three
questions arise from these findings: i) Why does the yield of rotaxane depend so much
on the nature of the stopper? ii) If this is due to an unfavorable competition between
axle and rotaxane formation, why is the free axle formed so much faster than the
rotaxane if 10 is applied as the stopper instead of 2? iii) What is the influence of the
center piece?

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Scheme 1. Rotaxane Synthesis as Described in [9]. Semi-axle 4 is formed under basic conditions from the axle-
center piece 1 and tritylphenol stopper 2. In a second step, 4 reacts with the stopper-wheel complex 2À ¥ 3 to yield
the rotaxane 5 ¥ 3.
Br
Br
1
K2CO3
O
Br
CH2Cl2
O
4
O
O
O
O
OH
N
N
H
H
H
N
H
N
O
O
O
O
2
N
H
N
H
K2CO3
CH2Cl2
O
H
N
H
N
O
1
2
46
O
O
O
N
N
H
38
H
39
H
H
N
N
20
O
2·3
5·3
3
Scheme 2. Synthesis of the Axle-Center Pieces 9a j with Central Alkyl Chains of Different Lengths
K2CO3
MeCN
O
O
OH
4
4'
Br
Br
OH
HO
HO
n
1
n
1'
7a-j
8a-j
70–90%
6
HBr (47%)
CH2Cl2
a n = 3
f n = 8
b n = 4
c n = 5
d n = 6
e n = 7
g n = 9
h n = 10
i n = 11
j n = 12
O
O
1
1'
Br
Br
n
4
4'
9a-j
92–96%
In this contribution, we first describe our attempts to optimize the rotaxane
synthesis, including changes of the reaction time, the use of different bases for
deprotonation of the phenolate, and the use of silver salts as bromide scavengers. The
latter modification strengthens the electrophilicity of the semi-axle by forming the
highly reactive benzyl cation almost instantaneously. Subsequently, the stopper-wheel
complexes are examined by molecular modeling. Significant geometric differences are

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Helvetica Chimica Acta Vol. 85 (2002)
Scheme 3. Competition between Formation of the Free Axle at a Reaction Rate k1 and the Rotaxane with a Rate
k2. Note that the equilibrium between the free stopper phenolate 10À and the phenolate-wheel complex 10À ¥ 3 is
completely shifted to the side of the complex as indicated by a binding constant of K > 105 mÀ1. Together with
the product ratio, one concludes that k1 must be at least six orders of magnitude higher than k2. The broken
arrow indicates the possibility that the stopper-wheel complex 10À ¥ 3 might also react in a way to produce the
free axle instead of the rotaxane.
OH
O
O
a n = 3
b n = 4
c n = 5
d n = 6
e n = 7
f n = 8
g n = 9
h n = 10
i n = 11
j n = 12
Br
Br
n
10
9a-j
K2CO3
in situ
CH2Cl2
O
O
Br
n
O
11a-j
O
O
O
O
O
O
O
O
N
H
N
H
N
H
N
H
–1
M
K > 105
O
H
N
H
N
H
N
H
N
10 ·3
3
O
11a-j k2
11a-j
O
10
?
O
O
O
N
N
H
O
11a-j k1
H
n
H
N
H
N
O
O
O
O
n
O
O
O
12a-j
(ca. 95%)
12a-j·3
(2 - 5%)
k1 >>> k2 ?

Helvetica Chimica Acta Vol. 85 (2002)
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observed for 2À ¥ 3 and 10À ¥ 3, which are in excellent qualitative agreement with the
experimental observations and give answers to the two questions above. The wheel
protects the stopper phenolates against attack by the semi-axle electrophile. This effect
depends much on the geometric demand of the stopper. Finally, a modified protocol
that improves the yield of rotaxanes significantly without much reducing the
practicability of the synthetic approach is described.
2. Synthetic Aspects and Attempts Aimed at ImprovingRotaxane Yield.
To
ensure comparability, the rotaxanes depicted in Fig. 1 were all repeatedly prepared
according to the protocol described by Vˆgtle and co-workers [9] and obtained with the
given yields. It is obvious that both the stoppers and the axle-center pieces strongly
influence on the rotaxane yields. While 5 ¥ 3 is formed almost quantitatively, the yield
drops significantly to 50 60%, if the smaller di(tert-butyl)phenol stopper is used.
Analogously, the combination of the tritylphenol stopper with center pieces 9f h gave
much higher yields (30 35%) than the same reaction aiming at rotaxanes 12a j ¥ 3 by
using the smaller stopper 10 (2 5%). Not only the stopper has a significant effect on
the yield, also the center piece plays a role, which becomes obvious when comparing
rotaxane 5 ¥ 3 with 14f h ¥ 3 and 13 ¥ 3 with 12a j ¥ 3 (Fig. 1).
When we first obtained yields of ca. 3% with rotaxane 12a ¥ 3, we hypothesized that
deslipping of the rotaxane would occur at a high rate and thus would explain the large
amount of free axle 12a formed during the reaction time of six days. However, such a
fast deslipping is not in agreement with the corresponding rates of similar rotaxanes
[11], which have a half-life at 608 on the order of 50 to 80 h and thus, at room
temperature, should be much longer-lived. Nevertheless, the reaction time was varied
from two to eight days in an effort to confirm higher yields at shorter time intervals.
However, this was not found. Together, these two results rule out deslipping as the
reason for the low rotaxane yields with the di(tert-butyl)phenol stopper 2.
Next, the role of the base was examined. It is not quite clear how fast deprotonation
of the phenolate occurs when potassium carbonate is used as the base. Definitely, in the
solid-liquid two-phase system with CH2Cl2, [18]crown-6 or its dibenzo derivative are
required as a phase-transfer catalyst. To completely deprotonate the phenol prior to the
reaction, stopper 10 was dissolved in CH2Cl2, and 1 equiv. of BuLi was added, followed
by the wheel 3 (Scheme 4,a). While the lithium phenolate did not precipitate, the
stopper-wheel complex immediately formed a white solid upon addition of the wheel.
The precipitate could easily be dissolved again by addition of [15]crown-5 which
‡
formed a complex with the Li ion and thus provided solubility. After addition of the
axle-center piece 9a, the reaction was complete within less than 24 h. The yields of
rotaxane 12a ¥ 3 and free axle 12a did not change significantly. Consequently, the base is
not the important factor, which can be understood if one assumes a rapid protonation-
deprotonation equilibrium prior to a slower, rate-determining nucleophilic displace-
ment reaction.
Finally, the role of the electrophile was tested. Since the reaction of a benzyl
bromide with a nucleophile is probably an SN1-type reaction, the electrophile might
play a more important role than the nucleophile. In nonpolar solvents like CH2Cl2,
however, formation of the benzyl cation is energetically unfavorable, so that addition of
a silver salt to precipitate the bromide and replace it with a more weakly binding

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Helvetica Chimica Acta Vol. 85 (2002)
O
O
O
O
O
O
O
O
O
O
N
N
H
N
H
N
H
H
H
N
H
N
H
N
H
N
O
O
5·3
13·3
(50–60%)
(80–95%)
O
O
O
O
O
O
O
O
O
O
N
N
H
N
N
H
O
O
H
H
n
n
H
N
H
N
H
H
N
O
O
N
O
O
12a-j·3
(2–5%)
14f-h·3
(30–35%)
Fig. 1. Rotaxane yields depending on the stoppers and center pieces. The yields of 5 ¥ 3 and 13 ¥ 3 are taken from
[9] and [11], resp.
counterion can be expected to yield better results. A solution of the stopper-wheel
complex 10À ¥ 3 was prepared as described above and then treated with the axle-center
piece 9a and 2 equiv. of AgNO3 or AgBF4 as bromide scavengers (Scheme 4,b). The
silver salts did not dissolve in CH2Cl2, but upon sonication for 15 min, AgBr was

Scheme 4. Variations of the Synthetic Protocol Aiming at an Improvement of the Rotaxane Yield. a) Complete deprotonation of the stopper 10 gives rise to an almost
quantitative complex formation with the wheel. b) Addition of a silver salt as bromide scavenger significantly increases the electrophilicity of the center piece by
benzyl-cation formation.
a)
O
O
O
O
N
H
N
H
O
OH
BuLi
3
O
H
N
H
N
[15]crown-5
11a
1 d
10
10 ·3
O
10
O
O
O
N
H
N
H
O
3
H
N
H
N
O
O
11a
AgNO3
O
b)
15 min
sonication
O
O
N
N
OH
O
BuLi
3
H
H
12a·3
O
H
N
H
N
(3–5%)
[15]crown-5
O
O
10
10 ·3
10

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Helvetica Chimica Acta Vol. 85 (2002)
formed concomitantly with the corresponding benzyl cations, which rapidly reacted
with the stopper-wheel complex. According to TLC, the reaction was finished within
15 min and again produced the same ratio of rotaxane and free axle. Thus, also the
electrophile does not exert significant influence on the products ratio.
From these results, the mechanistic scenario depicted in Scheme 3 can be derived. In
situ, the semi-axles 11a j are formed from phenol 10 and the center pieces 9a j.
Simultaneously, the phenolate 10À forms the stopper-wheel complex 10À ¥ 3 in an
equilibrium which is shifted completely to the side of the complex (K > 105 mÀ1). To
explain an approximate 9 :1 ratio of free axles 12a j and rotaxanes 12a j ¥ 3, two
competing reactions must be taken into account. While the formation of the free axles
from the semi-axles and the free phenolate proceeds at a rate k1, the rotaxane is
produced at a much lower rate k2. Taking into account a lower limit for the binding
constant of 105 mÀ1 and a product ratio of ca. 20 :1 in favor of the free axle, k1 must at
least be four to five orders of magnitude higher than k2, a factor that translates into
quite a large difference in the activation barrier (DEA). Two possible effects might
contribute to such an effect: i) The phenolate is H-bound, if complexed to the amide
protons of the tetralactam macrocycle. This might reduce the nucleophilicity of the
phenolate O-atom. However, this effect should similarly affect both stoppers 2 and 10.
Furthermore, in an SN1 displacement, nucleophilicity is not expected to be the
dominant factor. ii) Thus, steric effects might be invoked to rationalize the findings. The
phenolate O-atom can be expected to be buried within the cavity of the macrocycle so
that the attack path of the electrophile is obstructed by the wheel. Of course, this
analysis is based on the Arrhenius equation and assumes that the pre-exponential factor
of both reactions is closely similar. This assumption is, however, probably not entirely
correct, because the pre-exponential factor contains entropic contributions to the
activation barrier, which may be different for the free phenolate as compared to the
stopper-wheel complex. Nevertheless, the difference in EA must be significant with the
consequence that the competition between the two reactions characterized by k1 and k2
is likely not the only reason for the observed product ratio.
3. Molecular Modeling. To examine the steric requirements of the stopper-wheel
complexes 2À ¥ 3 and 10À ¥ 3 in greater detail, force-field calculations were performed
with the Amber* force field [12] as implemented in the MacroModel 7.1 program
package [13]. For a detailed mechanistic picture, one, of course, would have to calculate
not only the minima on the potential-energy surfaces, but also the transition structures.
This is, however, not feasible with molecules of the size and flexibility of the complexes
under discussion. Nevertheless, searching for the energetically most favorable
conformations of the stopper-wheel complexes may serve as a good approximation
and may at least give some indication why the reactivities of the two stoppers differ so
much.
To find those lowest-energy conformations (Figs. 2 and 3), Monte Carlo conforma-
tional searches were carried out in which 1000 structures were calculated for each of the
complexes. The differences between the two structures are clearly visible. While the
phenolate O-atom of the tritylphenol-derived stopper 2À is well-accessible for the
incoming electrophile in 2À ¥ 3 (Fig. 2, top left), it is buried under the Me groups of the
wheel×s dimethylaniline subunits in 10À ¥ 3 (Fig. 3, top left). Viewed from the opposite

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Fig. 2. Lowest-energy conformation of the tritylphenolate-wheel complex 2À ¥ 3 out of a 1000-step Monte Carlo
conformational search (Amber* force field as implemented in the MacroModel 7.1 program package). The tBu
group attached to the wheel is omitted. The complex is shown in the direction of the attacking electrophile (top
left), from the side (top middle), and from the side opposed to the electrophile (top right). The phenolate O-
atom although buried within the cavity is somewhat exposed towards attack of the electrophile. The bottom
picture shows the insertion of the stopper into the wheel. The frontal isophthalic acid is omitted to provide an
unobstructed view. Van der Waals radii of the remote wheel atoms are shown as dotted surfaces. The numbers
give distances in ä between the two pairs of Me groups as indicated; numbers in parentheses are average
distances of the thirty most favorable conformations).
direction (Figs. 2 and 3, top right), i.e., the side blocked by the stopper itself, the
phenolate O-atom of 2À ¥ 3 is hardly visible, while that of 10À ¥ 3 is much more freely
exposed to the environment. Consequently, attack of the electrophilic semi-axle seems
to be preferred through the wheel for 2À ¥ 3, while the formation of the axle might well

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Fig. 3. Lowest-energy conformation of the di(tert-butyl)phenolate-wheel complex 10À ¥ 3 shown in analogy to
Fig. 2. The complex offers a much more narrow attack path to the electrophile.
occur on the same side of the wheel for 10À ¥ 3. This process would lead to the free axle,
while 2À ¥ 3 would yield the rotaxane.
It is interesting to analyze the two structures in some more detail. The stoppers
induce quite different conformations of the wheel. For 2À ¥ 3, the two isophthalic acid
subunits are not parallel (Fig. 2, top middle), with the one involved in H-bonding being
tilted by ca. 408 against the other one. In 10À ¥ 3, both isophthalic acid building blocks
are more or less parallel (Fig. 3, top middle). Even more telling is the view at the
bottom of Figs 2 and 3. The two dimethylaniline rings neighboring the H-bonding site
are almost parallel for 2À ¥ 3, opening a rather comfortable −access road× for the semi-
axle. Instead, these rings are conically tilted with the two upper Me groups hindering
the electrophile to react in a rotaxane-producing way. These differences can be
quantified by the distances between the Me groups as indicated in Figs. 2 and 3. While

Helvetica Chimica Acta Vol. 85 (2002)
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the C ¥¥¥ C distance is almost 7 ä for complex 2À ¥ 3, it is almost 2 ä smaller for 10À ¥ 3.
Vice versa, the two Me groups on the other side of the wheel are more distant in the
latter case than for 2À ¥ 3 (8.6 ä vs. 7.3 ä).
The differences between the two conformations become even clearer when one
takes a closer look at the H-bonding pattern (Fig. 4). The nucleophilic, negatively
charged phenolate O-atom bears three lone pairs, two of which are involved in the
formation of the two H-bonds to the two amide protons. The third, which is likely the
reactive one, forms the axle with the semi-axle benzyl cation. The two different
conformations also differ with respect to the location of this lone pair. For 2À ¥ 3, it is
positioned exactly as required for productive rotaxane formation (arrow in Fig. 4,a),
while it is located on the same side of the wheel as the stopper for 10À ¥ 3 (Fig. 4,b).
Consequently, for the di(tert-butyl)phenol stopper, formation of the free axle will be
preferred even from the stopper-wheel complex.
These arguments are in excellent agreement with the experimental findings and
offer a good rationalization for the differences in the behavior of the two stoppers.
However, one might argue that a simple force-field calculation might be somewhat
uncertain. Therefore, we looked for other conformation among the higher-energy
structures optimized during the Monte Carlo search. Indeed, two families of
conformations exist for both stopper-wheel complexes1), of which the two structures
discussed above are representative. However, these structures are not evenly
distributed over the energy range of the calculations. While for 2À ¥ 3, structures with
a conformation similar to that depicted in Fig. 2 dominate, in particular for lower
energies (the first 26 structures all belong to this family and have calculated energies of
formation in a range of 26 kJ/mol above the lowest-energy conformer), for 10À ¥ 3,
more geometries like that in Fig. 3 are found at lower energies, while conformations
similar to that in Fig. 2 become more frequent at higher energies. Six of those structures
similar to that in Fig. 3 exist among the lowest ten conformers, but only eight among the
first 30 conformers. This is also reflected in the Me ¥¥¥ Me distances. The values in
parentheses give the average distances for the thirty lowest-energy conformers of each
complex. Still, there is a difference between the two complexes of almost 1 ä (6.4 ä for
2À ¥ 3 vs. 5.6 ä for 10À ¥ 3). Thus, one can expect that 2À ¥ 3 more frequently populates the
open conformation that leads to the rotaxane, while 10À ¥ 3 prefers the other geometry
that forms the free axle.
Of course, this picture does not rule out the possibility that the free stopper reacts
more quickly than the stopper-wheel complex. However, the scenario developed with
the help of molecular modeling offers a second alternative, which avoids the
assumption of the large difference in activation energies for axle and rotaxane
formation. Instead of competition between the free stopper and the stopper-wheel
complex, the reaction may also involve competition between the two different
conformations of the stopper-wheel complex, one giving rise to the rotaxane, the other
1
)
A third family was found among the structures higher in energy for 10À ¥ 3 in which the stopper is not
inserted into the wheel with one Bu group as in Fig. 3, but rotated by 908 and positioned in a coplanar
t
fashion relative to the wheel. In these conformations, the two tBu groups of the stopper are located in close
proximity to the two Me groups of the neighboring dimethylaniline rings and force these two aromatic rings
into a conical conformation similar to that shown in Fig. 3. Consequently, these conformations will have an
effect similar to that of those represented by the structure shown in Fig. 3.

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Fig. 4. Stopper-wheel complexes a) 2À ¥ 3 and b) 10À ¥ 3 in a side view with the remote parts of the wheel shown as
dotted Van der Waals surfaces. The solid atoms represent the stoppers and the isophthalic diamide subunit
involved in H-bonding. The arrows point to the free electron pair of the phenolate O-atom not H-bound to the
two amide protons and thus indicate the preferred attack path of the electrophile.
yielding the free axle (dotted arrow in Scheme 3). The observed product distributions
may nevertheless be due to a combination of both effects.
4. The Axle-Center Pieces.
Although we cannot give as nearly detailed a
rationalization for the influence of the axle-center pieces, one can, of course, speculate
why the yields are smaller for the longer, ether-bearing center pieces in 12a j ¥ 3 and
14f h ¥ 3 (Fig. 1). One issue, certainly, is flexibility. The transition structure for the
reaction giving rise to the rotaxanes is expected to be entropically unfavorable, because
it requires a rather precise arrangement of the reaction partners inside the cavity of the
macrocycle. Consequently, a rather flexible center piece might require that a larger
number of rotations around the central single bonds be frozen out and, thus, would be
entropically disfavored over a less-flexible center piece such as 1. Another effect might
be due to differences in solvation. While the center pieces 9a j bear ether groups that
make the attached aromatic rings somewhat more electron rich, such groups are absent
in 1. However, for the time being, the details of these influences remain unknown and
speculative.
5. A Synthetic Protocol ImprovingRotaxane Yields and Practicability. As neither
changes in the reaction time nor the use of different bases or silver salts as bromide
scavengers led to an improved rotaxane yield, there was not much room left for a
further optimization. More competitive solvents reduce the strength of the H-bonds in

Helvetica Chimica Acta Vol. 85 (2002)
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the stopper-wheel complex and thus have a negative influence on the template effect.
Consequently, CH2Cl2 is the best compromise between low polarity and the absence of
H-bond donors or acceptors on the one hand and the solubility of the reaction partners
on the other. According to our experience, other solvents do not increase the yield of
rotaxane, because either the components are not soluble enough or the solvents are too
competitive and interfere with the template effect by H-bond formation.
Ayield of 2 5% in a synthesis of a rotaxane is nevertheless rather disappointing, in
particular as the preparation of the wheel involves a macrocyclization step that
proceeds at rather low yields (30 50%) as well and requires a tedious chromato-
graphic purification to separate the wheel from catenanes, larger wheels, and polymers
formed simultaneously, even under high-dilution conditions. Thus, we searched for
other ways to improve the synthetic scheme. One possibility is, of course, to not only
isolate the rotaxane from the reaction mixture, but to also recover the remaining
portion of the macrocycle and recycle it in another reaction. However, this procedure
still requires quite an effort during chromatography with very high consumption of
stationary phase and solvents.
Since the axle-center pieces and the stoppers are either commercially available at
low cost or straighforward to produce in larger quantities, the wheel is the most
precious material required for the synthesis of the rotaxanes. Thus, it would be a
significant improvement, if an excess of center piece and stopper would lead to an
increased consumption of the wheel. Relative to the amount of wheel used as the
reactant, higher yields would be achieved; simultaneously, also an accordingly large
excess of the free axle would be formed, which can, however, be separated from the
rotaxane by chromatography due to a difference in the Rf values of ca. 0.5 (rotaxane Rf
0.2 0.3 and axle Rf 0.7 0.75 in CH2Cl2/AcOEt 30 :1).
With some optimization, the rotaxane yields could be increased significantly to 20
25% relative to the wheel by adding six additional portions of 1 equiv. of the center
piece and 2 equiv. of the stopper to the reaction mixture at equivalent time intervals of
several hours (Protocol B, see Exper. Part). The stepwise procedure turned out to work
somewhat better than the addition of the total amount of all the reactants at the
beginning of the reaction. Of course, adding more aliquots of center pieces and stoppers
(as long as there is an excess of base present) may even give rise to higher yields. To find
the optimum for a given rotaxane, many factors should be taken into account, e.g., the
costs of the stoppers and center pieces, chromatographic separability of the rotaxane
from the excess of the free axle, deslipping as a competing reaction for stoppers of
smaller sizes, or the reaction time.
6. Conclusions. Starting from a notoriously unsuccessful synthesis of rotaxanes, we
found a surprising influence of stopper geometry on the rotaxane yield. An analysis of
the template effect by a series of experiments and Monte Carlo calculations offers an
interesting and conclusive rationalization for these findings. Based on this model, a
synthetic protocol improving the yield and practicability was developed and used for
the synthesis of new rotaxanes with different axle lengths.

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We are grateful to Prof. Fritz Vˆgtle for generous support and fruitful discussions. C.A.S. thanks the Fonds
der Chemischen Industrie for a Liebig Fellowship and the Deutsche Forschungsgemeinschaft for financial
support. C.F.N. is grateful to the Studienstiftung des Deutschen Volkes for a fellowship.
Experimental Part
Monte Carlo Conformational Searches. The two stopper-wheel complexes 2À ¥ 3 and 10À ¥ 3 were examined
with the Amber* force field [12]. The lowest-energy conformers out of 1000 structures were determined with
the Monte Carlo algorithm as implemented in the MacroModel 7.1 program package [13]. Closure bonds were
placed in the macrocycle (one of the amide bonds) and the two spirocyclohexane moieties. While the aromatic
rings and the amide moieties were constrained to planarity, all single bonds (with the exception of the Me
groups) were selected to allow rotations into other conformations. Finally, phenolate and wheel were treated as
independent molecules able to move relative to each other. In order not to increase the number of degrees of
freedom more than necessary, the tBu group attached to the wheel was omitted. At the same time, this
symmetrized the wheel so that no distinction between the two possible binding sides was necessary. The energy
range for structures to store in the output file was set to 50 kJ/mol above the lowest-energy conformer.
General. The 4-(triphenylmethyl)phenol (2) and 3,5-di(tert-butyl)phenol (10) were used as purchased from
Lancaster and Aldrich, resp. Macrocycle 3 [14], compounds 8a c, 9a, and 9b [15] and rotaxanes 5 ¥ 3 [9] and 13 ¥
3 [11] were synthesized according to well-established literature procedures. CC ˆ column chromatography.
NMR Spectra: Bruker instruments at 250, 300, or 400 MHz for 1H and 62.5, 75, or 100 MHz for 13C; solvent
signal as internal standard; d in ppm, J in Hz; in general, the formation of a rotaxane led to upfield shifts of the
signals for the aromatic protons in the axle-center pieces due to the anisotropy of the aromatic rings
incorporated in the wheel (signals easily detected at d(H) ca. 6.0 and 6.7) ppm; chx ˆ spirocyclohexane moieties.
EI-, FAB- (Kratos Concept 1 H) and MALDI-TOF (Micromass MALDI-TofSpec-E) mass spectra: in m/z (rel.
%); standard matrices 3-nitrobenzyl alcohol and 2,5-dihydroxybenzoic acid, resp.; isotope patterns in MALDI-
MS (not superimposed by fragmentations such as H losses) in excellent agreement with calc. patterns based on
the elemental composition and natural isotope abundances; signals present for the protonated or sodiated wheel
in all MALDI and FAB-MS of rotaxanes, due to partial deslipping upon ionization or formed from the rotaxane
loss of one stopper and dethreading of the remaining semi-axle. Elemental analyses were unsatisfying due to
unavoidable problems, NMR-detectable inclusion of solvent molecules in the wax-like rotaxanes.
Compounds 8a j: General Procedure. A mixture of 4-hydroxybenzyl alcohol (0.1 mol), the corresponding
1,w-dibromoalkane 7a j (0.05 mol) and K2CO3 (0.2 mol) in MeCN (500 ml) was refluxed for 24 h. After
cooling to r.t., the MeCN was evaporated and the residue partitioned between H2O and CH2Cl2. The aq. phase
was extracted several times with CH2Cl2 and the combined org. phase dried (MgSO) and evaporated.
Compounds 8a j precipitated as white solids and were purified by recrystallization from acetone.
1
4,4'-[Hexane-1,6-diylbis(oxy)]bis[benzenemethanol] (8d). H-NMR (250 MHz, CDCl3/CD3OD 2 :1): 1.32
1.40 (m, 2 CH2); 1.55 1.70 (m, 2 CH2); 3.85 (t, 2 CH2O); 4.41 (s, 2 CH2OH); 6.73 (AA' of AA'XX', 3J ˆ 8.6,
4 arom. H); 7.15 (XX' of AA'XX', 3J ˆ 8.6, 4 arom. H). 13C-NMR (62.5 MHz, CDCl3/CD3OD 2 :1): 160.1; 134.9;
.
‡
‡
130.5; 116.1; 69.7; 66.0; 31.0; 27.6. FAB-MS (C20H26O4): 330.2 (15, M ), 313.2 (100, [M ‡ H À H2O] ).
4,4'-[Heptane-1,7-diylbis(oxy)]bis[benzenemethanol] (8e). 1H-NMR (300 MHz, CDCl3/CD3OD 2 :1):
1.30 1.44 (m, 3 CH2); 1.52 1.71 (m, 2 CH2); 3.87 (t, 2 CH2O); 4.45 (s, 2 CH2OH); 6.75 (AA' of AA'XX',
3J ˆ 8.6, 4 arom. H); 7.18 (XX' of AA'XX', 3J ˆ 8.6, 4 arom. H). 13C-NMR (75 MHz, CDCl3/CD3OD 2 :1): 160.3;
.
‡
‡
‡
134.9; 130.3; 116.2; 69.8; 66.0; 30.9; 30.8; 27.7. FAB-MS: 344.1 (5, C21H28O4 ; M ), 327.1 (100, [M ‡ H À H2O] ).
4,4'-[Octane-1,8-diylbis(oxy)]bis[benzenemethanol] (8f). 1H-NMR (250 MHz, CDCl3/CD3OD 2 :1): 1.30
1.48 (m, 4 CH2); 1.58 1.70 (m, 2 CH2); 3.82 (t, 2 CH2O); 4.42 (s, 2 CH2OH); 6.76 (AA' of AA'XX', 3J ˆ 8.6,
4 arom. H); 7.13 (XX' of AA'XX', 3J ˆ 8.6, 4 arom. H). 13C-NMR (62.5 MHz, CDCl3/CD3OD 2 :1): 159.5; 134.7;
.
‡
‡
‡
129.8; 116.1; 70.5; 66.2; 30.3; 30.2, 27.1. FAB-MS: 358.2 (4, C22H30O4 ; M ), 341.2 (100, [M ‡ H À H2O] ).
4,4'-[Nonane-1,9-diylbis(oxy)]bis[benzenemethanol] (8g). 1H-NMR (250 MHz, CDCl3/CD3OD 2 :1):
1.32 1.71 (m, 7 CH2); 3.90 (t, 2 CH2O); 4.60 (s, 2 CH2OH); 6.92 (AA' of AA'XX', 3J ˆ 8.6, 4 arom. H); 7.25
(XX' of AA'XX', 3J ˆ 8.6, 4 arom. H). 13C-NMR (62.5 MHz, CDCl3/CD3OD 2 :1): 160.2; 134.7; 130.0; 116.4;
.
‡
‡
‡
69.7; 66.0; 29.9; 29.8; 29.7; 27.7. FAB-MS: 372.0 (3, C23H32O4 ; M ), 355.0 (100, [M ‡ H À H2O] ).
4,4'-[Decane-1,10-diylbis(oxy)]bis[benzenemethanol] (8h). 1H-NMR (300 MHz, CDCl3/CD3OD 2 :1):
3
1.22 1.46 (m, 6 CH2); 1.64 1.80 (m, 2 CH2); 3.91 (t, 2 CH2O); 4.50 (s, 2 CH2OH); 6.86 (AA' of AA'XX', J ˆ
8.6, 4 arom. H); 7.22 (XX' of AA'XX', 3J ˆ 8.6, 4 arom. H). 13C-NMR (75 MHz, CDCl3/CD3OD 2 :1): 158.9;
.
‡
‡
133.6; 128.9; 114.8; 68.5; 64.5; 29.9; 29.8; 29.7; 26.4. FAB-MS: 386.3 (5, C24H34O4 ; M ), 369.2 (100, [M ‡ H À
‡
H2O] ).

Helvetica Chimica Acta Vol. 85 (2002)
1591
4,4'-[Undecane-1,11-diylbis(oxy)]bis[benzenemethanol] (8i). 1H-NMR (300 MHz, CDCl3/CD3OD 2 :1):
3
1.25 1.47 (m, 7 CH2); 1.60 1.77 (m, 2 CH2); 3.87 (t, 2 CH2O); 4.46 (s, 2 CH2OH); 6.77 (AA' of AA'XX', J ˆ
8.6, 4 arom. H); 7.15 (XX' of AA'XX', 3J ˆ 8.6, 4 arom. H). 13C-NMR (75 MHz, CDCl3/CD3OD 2 :1): 160.3;
.
‡
‡
134.9; 130.3; 116.2; 69.9; 66.0; 31.2; 31.2; 31.1; 31.0; 30.4; 29.8; 27.7. FAB-MS: 400.2 (3, C25H36O4 ; M ), 383.2
‡
(100, [M ‡ H À H2O] ).
4,4'-[Dodecane-1,12-diylbis(oxy)]bis[benzenemethanol] (8j). 1H-NMR (300 MHz, CDCl3/CD3OD 2 :1):
3
1.22 1.46 (m, 8 CH2); 1.62 1.80 (m, 2 CH2); 3.91 (t, 2 CH2O); 4.47 (s, 2 CH2OH); 6.82 (AA' of AA'XX', J ˆ
8.6, 4 arom. H); 7.21 (XX' of AA'XX', 3J ˆ 8.6, 4 arom. H). 13C-NMR (75 MHz, CDCl3/CD3OD 2 :1): 158.9;
.
‡
‡
133.5; 128.9; 114.8; 68.5; 64.5; 29.9; 29.9; 29.8; 29.6; 29.4; 26.4. FAB-MS: 414.2 (4, C26H38O4 ; M ), 397.2 (100,
‡
[M ‡ H À H2O] ).
Compounds 9a j. General Procedure [15]. Compounds 8a j (20 mmol) were added to a two-phase system
of 47% HBr soln. (50 ml) and CH2Cl2 (150 ml) and stirred rapidly for 1 h. After extraction of the mixture with
CH2Cl2, the org. layers were washed with sat. NaHCO3 soln. and brine and dried (MgSO4). After evaporation,
the remaining solids were immediately used for rotaxane synthesis.
1,1'-[Pentane-1,5-diylbis(oxy)]bis[4-(bromomethyl)benzene] (9c). 1H-NMR (300 MHz, CDCl3): 1.50 1.60
(m, 1 CH2); 1.75 1.90 (m, 2 CH2); 3.95 (t, 2 CH2O); 4.45 (s, 2 CH2Br); 6.89 (AA' of AA'XX', 3J ˆ 8.7,
4 arom. H); 7.30 (XX' of AA'XX', 3J ˆ 8.7, 4 arom. H). 13C-NMR (75 MHz, CDCl3): 159.6; 130.8; 130.2; 115.2;
.
‡
‡
‡
68.2; 34.4; 29.4; 23.1. EI-MS (70 eV): 444 (2), 442 (5), 440 (2, C19H22Br2O2 ; M ), 363 (69), 361 (70, [M À Br] ),
.
‡
‡
‡
282 (2, [M À 2Br] ), 257 (29), 255 (27, [BrCH2C6H4OC5H10] ), 107 (100, [HOC6H4CH2] ).
1,1'-[Hexane-1,6-diylbis(oxy)]bis[4-(bromomethyl)benzene] (9d). 1H-NMR (250 MHz, CDCl3): 1.51 1.63
(m, 2 CH2); 1.72 1.88 (m, 2 CH2); 3.90 (t, 2 CH2O); 4.38 (s, 2 CH2Br); 6.75 (AA' of AA'XX', 3J ˆ 8.7,
4 arom. H); 7.33 (XX' of AA'XX', 3J ˆ 8.7, 4 arom. H). 13C-NMR (62.5 MHz, CDCl3): 160.2; 130.9; 130.1; 115.5;
.
‡
‡
68.8; 33.9; 29.5; 23.1. EI-MS (70 eV): 458 (3), 456 (6), 454 (3, C20H24Br2O2 ; M ), 377 (39), 375 (40, [M À
.
‡
‡
‡
Br] ), 296 (5, [M À 2Br] ), 107 (100, [HOC6H4CH2] ).
1,1'-[Heptane-1,7-diylbis(oxy)]bis[4-(bromomethyl)benzene] (9e). 1H-NMR (300 MHz, CDCl3): 1.51
1.63 (m, 3 CH2); 1.70 1.89 (m, 2 CH2); 3.85 (t, 2 CH2O); 4.43 (s, 2 CH2Br); 6.90 (AA' of AA'XX', 3J ˆ 8.7,
4 arom. H); 7.31 (XX' of AA'XX', 3J ˆ 8.7, 4 arom. H). 13C-NMR (75 MHz, CDCl3): 159.6; 130.8; 130.1; 115.1;
.
‡
‡
68.4; 34.4; 29.6; 29.5; 26.3. EI-MS: (70 eV): 472 (1), 470 (2), 468 (1, C21H26Br2O2 ; M ), 391 (59), 389 (61, [M À
.
‡
‡
‡
Br] ), 310 (4, [M À 2Br] ), 107 (100, [HOC6H4CH2] ).
1
1,1'-[Octane-1,8-diylbis(oxy)]bis[4-(bromomethyl)benzene] (9f). H-NMR (250 MHz, CDCl3): 1.50 1.57
(m, 4 CH2); 1.69 1.85 (m, 2 CH2); 3.91 (t, 2 CH2O); 4.49 (s, 2 CH2Br); 6.85 (AA' of AA'XX', 3J ˆ 8.7,
4 arom. H); 7.29 (XX' of AA'XX', 3J ˆ 8.7, 4 arom. H). 13C-NMR (62.5 MHz, CDCl3): 159.5; 131.0; 130.2; 115.3;
.
‡
‡
68.3; 34.4; 29.6; 29.5; 26.3. EI-MS (70 eV): 486 (2), 484 (4), 482 (2, C22H28Br2O2 ; M ), 405 (65), 403 (64, [M À
.
‡
‡
‡
Br] ), 324 (6, [M À 2Br] ), 107 (100, [HOC6H4CH2] ).
1,1'-[Nonane-1,9-diylbis(oxy)]bis[4-(bromomethyl)benzene] (9g). 1H-NMR (250 MHz, CDCl3): 1.50 1.90
(m, 7 CH2); 3.95 (t, 2 CH2O); 4.49 (s, 2 CH2Br); 6.85 (AA' of AA'XX', 3J ˆ 8.7, 4 arom. H); 7.25 (XX' of
AA'XX', 3J ˆ 8.7, 4 arom. H). 13C-NMR (62.5 MHz, CDCl3): 159.5; 130.5; 129.8; 115.0; 68.5; 34.6; 29.6; 29.5;
.
‡
‡
‡
29.4; 26.1. EI-MS (70 eV): 500 (3), 498 (5), 496 (2, C23H30Br2O2 ; M ), 419 (54), 417 (55, [M À Br] ), 338 (3,
.
‡
[M À 2Br] ‡ ), 107 (100, [HOC6H4CH2] ).
1,1'-[Decane-1,10-diylbis(oxy)]bis[4-(bromomethyl)benzene] (9h). 1H-NMR (250 MHz, CDCl3): 1.45
1.70 (m, 6 CH2); 1.73 1.91 (m, 2 CH2); 3.95 (t, 2 CH2O); 4.50 (s, 2 CH2Br); 6.85 (AA' of AA'XX', 3J ˆ 8.7,
4 arom. H); 7.33 (XX' of AA'XX', 3J ˆ 8.7, 4 arom. H). 13C-NMR (62.5 MHz, CDCl3): 159.0; 130.2; 129.8; 114.5;
.
‡
‡
67.9; 34.0; 29.5; 29.3; 29.1; 26.2. EI-MS (70 eV): 514 (2), 512 (5), 510 (3, C24H32Br2O2 ; M ), 433 (69), 431 (70)
.
‡
‡
‡
[M À Br] ), 352 (7, [M À 2Br] ), 107 (100, [HOC6H4CH2] ).
1,1'-[Undecane-1,11-diylbis(oxy)]bis[4-(bromomethyl)benzene] (9i). 1H-NMR (300 MHz, CDCl3): 1.44
1.69 (m, 7 CH2); 1.76 1.87 (m, 2 CH2); 3.89 (t, 2 CH2O); 4.43 (s, 2 CH2Br); 6.92 (AA' of AA'XX', 3J ˆ 8.7,
4 arom. H); 7.29 (XX' of AA'XX', 3J ˆ 8.7, 4 arom. H). 13C-NMR (75 MHz, CDCl3): 159.6; 130.8; 130.1; 115.2;
.
‡
‡
68.5; 34.3; 29.9; 29.8; 29.8; 29.6; 26.4. EI-MS (70 eV): 528 (2), 526 (4), 524 (4, C25H34Br2O2 ; M ), 447 (45), 445
.
‡
‡
‡
(46, [M À Br] ), 464 (5, [M À 2Br] ), 107 (100, [HOC6H4CH2] ).
1,1'-[Dodecane-1,12-diylbis(oxy)]bis[4-(bromomethyl)benzene] (9j). 1H-NMR (300 MHz, CDCl3): 1.28
1.56 (m, 8 CH2); 1.69 1.85 (m, 2 CH2); 3.94 (t, 2 CH2O); 4.49 (s, 2 CH2Br); 6.84 (AA' of AA'XX', 3J ˆ 8.7,
4 arom. H); 7.31 (XX' of AA'XX', 3J ˆ 8.7, 4 arom. H). 13C-NMR (75 MHz, CDCl3): 159.3; 130.4; 129.7; 114.7;
.
‡
‡
68.0; 34.1; 29.5; 29.4; 29.3; 29.2; 26.0. EI-MS (70 eV): 542 (3), 540 (5), 538 (3, C26H36Br2O2 ; M ), 461 (49), 459
.
‡
‡
‡
(48, [M À Br] ), 478 (4, [M À 2Br] ), 107 (100, [HOC6H4CH2] ).
Rotaxanes: Protocol A, General Procedure [9]. Wheel 3 was stirred in CH2Cl2 together with 1 equiv. of the
dibromide axle-center piece 9a j, 2 equiv. of the stopper 2 or 10, 0.25 equiv. of dibenzo[18]crown-6, and an

1592
Helvetica Chimica Acta Vol. 85 (2002)
excess of K2CO3 for 6 days. After evaporation, the rotaxane was purified by CC (CH2Cl2/AcOEt gradient
30 :1 ! 10 :1, silica gel (40 63 m)). The rotaxanes were obtained as colorless wax-like, sometimes oily
substances, the melting points of which could not be determined.
Rotaxanes: Protocol B, General Procedure. Wheel 3 was stirred in CH2Cl2 together with 1 equiv. of the
dibromide axle-center piece 9a j, 2equiv. of the stopper 2 or 10, 0.5 equiv. of dibenzo[18]crown-6, and an excess
of K2CO3 for 3 days. During this period, six additional portions of 1 equiv. of 9a j and 2 equiv. of the stopper
each were added after more or less equidistant time intervals. The rotaxane was purified by CC (see above).
Rotaxane 12a ¥ 3: Protocol C, via Complete Deprotonation prior to Axle Formation. Stopper 10 was
dissolved in CH2Cl2 and cooled in an ice bath to 08. Slowly, 1 equiv. of BuLi in hexanes was added for complete
deprotonation. After warming to r.t., wheel 3 was added in an equimolar amount. The generation of the stopper
wheel complex 10À ¥ 3 was indicated by the formation of a precipitate which completely dissolves again after
addition of 1 equiv. of [15]crown-5. Addition of the axle-center piece and stirring for 24 h yielded the rotaxane
and free axle, which were purified by CC (see above).
Rotaxane 12a ¥ 3: Protocol D, via Complete Deprotonation of the Stopper and Addition of AgNO3 as a
Bromide Scavenger. The stopper wheel complex 10À ¥ 3 was generated as described in Protocol C. After addition
of the axle-center piece, 2 equiv. of AgNO3 (or AgBF4) was added. The silver salt was hardly soluble in CH2Cl2,
and sonication for 15 to 30 min was applied to increase the reactive surface. Immediately, AgBr precipitated.
After completion of the reaction, the precipitate was filtered off and the filtrate purified as indicated above.
[2]{1,1'-[Propane-1,3-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31,(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane (12a ¥ 3): Rf 0.18 (CH2Cl2/AcOEt 30 :1). Yield 3% (A), 23% (B).
1H-NMR (400 MHz,C2D2Cl4): 1.25 (s, 4 tBu (axle)); 1.44 (s, 1 tBu (wheel)); 1.60 (br., 2 CH2 (chx)); 1.68 (q, 3J ˆ
6.0, 2 H, CH2 (axle)); 1.74 (br., 4 CH2 (chx)); 1.98 (s, 4 Me (wheel)); 2.00 (s, 4 Me (wheel)); 2.41 (br., 4 CH2
(chx)); 3.85 (t, 3J ˆ 6.0, 2 CH2O (axle)); 4.59 (s, 2 CH2O (axle)); 6.14 (AA'of AA'XX', 3J ˆ 8.5, 4 arom. H
(axle)); 6.54 (XX' of AA'XX', 3J ˆ 8.5, 4 arom. H (axle)); 6.66 (br. s, 4 NH); 7.04 (s, 2 arom. H (axle)); 7.08
(s, 4 arom. H (wheel)); 7.10 (s, 4 arom.H (wheel)); 7.32 (s, 4 arom. H (axle)); 7.66 (s, 1 arom. H (wheel)); 7.68
(t, 3J ˆ 7.7, 1 arom. H (wheel )) ; 7.80 (s, 1 arom. H (wheel)); 8.17 (d, 3J ˆ 7.7, 2 arom. H (wheel)); 8.21
(s, 2 arom. H (wheel)). 13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.9; 28.5; 31.0; 31.2; 31.8; 34.6; 35.0; 35.4; 45.3;
64.7; 69.7; 108.5; 114.4; 114.5; 114.6; 115.7; 126.6; 126.7; 128.5; 128.9; 129.1; 130.9; 131.1; 134.2; 134.4; 134.9;
‡
‡
135.0; 148.7; 152.3; 157.6; 157.8; 164.8; 165.2. MALDI-TOF-MS 1662.9 (67, C109H132KN4O8 , [M ‡ K ]), 1646.9
‡
‡
‡
‡
(100, [M ‡ Na] ), 998.7 (27, [wheel ‡ K] ), 982.8 (65, [wheel ‡ Na] ), 960.8 (66, [wheel ‡ H] ).
[2]{1,1'-[Butane-1,4-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl]benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31,(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane (12b ¥ 3): Rf 0.20 (CH2Cl2/AcOEt 30 :1). Yield 5% (A), 21% (B).
1H-NMR (400 MHz, C2D2Cl4): 1.25 (s, 4 tBu (axle)); 1.44 (s, 1 tBu (wheel)); 1.61 (br., 2 CH2 (chx)); 1.65 1.84
(m, 6 CH2 (chx, axle)); 1.98 (s, 4 Me (wheel)); 2.01 (s, 4 Me (wheel)); 2.42 (br., 4 CH2 (chx)); 3.75 (t, 3J ˆ 6.9,
2 CH2O (axle)); 4.60 (s, 2 CH2O (axle)); 6.15 (AA' of AA'XX', 3J ˆ 8.5, 4 arom. H (axle)); 6.56 (XX' of
AA'XX', 3J ˆ 8.5, 4 arom. H (axle)); 6.66 (br. s, 4 NH); 7.04 (s, 2 arom. H (axle)); 7.09 (s, 4 arom. H (wheel));
7.10 (s, 4 arom. H (wheel)); 7.29 (s, 4 arom. H (axle)); 7.72 (s, 1 arom. H (wheel)); 7.73 (t, 3J ˆ 7.7, 1 arom. H
(wheel)); 7.85 (s, 1 arom. H (wheel)); 8.21 (d, 3J ˆ 7.7, 2 arom. H (wheel)); 8.23 (s, 2 arom. H (wheel)).
13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.5; 25.7; 29.5; 31.0; 31.2; 31.8; 34.6; 35.0; 35.8; 45.3; 64.7; 67.4; 108.6;
114.3; 114.4; 114.6; 115.7; 126.5; 126.7; 128.5; 128.7; 129.1; 130.9; 131.1; 134.1; 134.3; 135.0; 152.3; 157.6; 158.0;
‡
‡
‡
164.8; 165.2. MALDI-TOF-MS: 1678.8 (12, C110H134KN4O8 [M ‡ K ]), 1662.8 (87, [M ‡ Na] ), 999.4 (15,
‡
‡
‡
[wheel ‡ K] ), 983.4 (100, [wheel ‡ Na] ), 961.4 (65, [wheel ‡ H] ).
[2]{1,1'-[Pentane-1,5-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane (12c ¥ 3): Rf 0.21 (CH2Cl2/AcOEt 30 :1). Yield 5% (A), 19% (B).
1H-NMR (400 MHz, C2D2Cl4): 1.20 1.30 (m, 1 CH2 (axle)); 1.25 (s, 4 Bu (axle)); 1.43 (s, 1 tBu (wheel)); 1.62
t
(br., 2 CH2 (chx)); 1.65 1.84 (m, 6 CH2 (chx, axle)); 1.98 (s, 4 Me (wheel)); 2.01 (s, 4 Me (wheel)); 2.41 (br.,
4 CH2 (chx)); 3.72 (t, 3J ˆ 6.2, 2 CH2O (axle)); 4.60 (s, 2 CH2O (axle)); 6.17 (AA' of AA'XX', 3J ˆ 8.5, 4 arom. H
(axle)); 6.46 (XX' of AA'XX', 3J ˆ 8.5, 4 arom. H (axle)); 6.67 (br. s, 4 NH); 7.05 (s, 2 arom. H (axle)); 7.09
(s, 4 arom. H (wheel)); 7.10 (s, 4 arom. H (wheel)); 7.35 (s, 4 arom. H (axle)); 7.69 (s, 1 arom. H (wheel)); 7.70
(t, 3J ˆ 7.7, 1 arom. H (wheel)); 7.84 (s, 1 arom. H (wheel)); 8.20 (d, 3J ˆ 7.7, 2 arom. H (wheel)); 8.22

Helvetica Chimica Acta Vol. 85 (2002)
1593
(s, 2 arom. H (wheel)). 13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.9; 28.5; 31.0; 31.1; 31.2; 31.8; 34.7; 35.0; 35.4;
45.3; 64.7; 69.7; 108.6; 114.4; 114.5; 114.6; 115.7; 126.5; 126.7; 128.5; 128.9; 129.1; 130.9; 131.1; 134.2; 134.3;
‡
134.9; 135.0; 148.8; 152.3; 157.6; 158.1; 158.4; 164.7; 165.1. MALDI-TOF-MS: 1692.0 (42, C111H136KN4O8 [M ‡
‡
‡
‡
‡
‡
K ]), 1676.0 (100, [M ‡ Na] ), 99.2 (20, [wheel ‡ K] ), 983.2 (88, [wheel ‡ Na] ), 961.2 (91, [weel ‡ H] ).
[2]{1,1'-[Hexane-1,6-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane 12d ¥ 3): Rf 0.21 (CH2Cl2/AcOEt 30 :1): Yield 3% (A), 16% (B).
1H-NMR (400 MHz, C2D2Cl4): 1.20 1.30 (m, 2 CH2 (axle)); 1.25 (s, 4 tBu (axle)); 1.44 (s, 1 tBu (wheel)); 1.62
(br., 2 CH2 (chx)); 1.65 1.84 (m, 6 CH2 (chx, axle)); 1.98 (s, 4 Me (wheel)); 2.01 (s, 4 Me (wheel)); 2.42 (br., 4
CH2 (chx)); 3.73 (t, 3J ˆ 6.5, 2 CH2O (axle)); 4.60 (s, 2 CH2O (axle)); 6.17 (AA' of AA'XX', 3J ˆ 8.3, 4 arom. H
(axle)); 6.45 (XX' of AA'XX', 3J ˆ 8.3, 4 arom. H (axle)); 6.67 (br. s, 4 NH); 7.05 (s, 2 arom. H (axle)); 7.09
(s, 4 arom. H (wheel)); 7.10 (s, 4 arom. H (wheel)); 7.36 (s, 4 arom. H (axle)); 7.69 (s, 1 arom. H (wheel)); 7.71
(t, 3J ˆ 7.8, 1 arom. H (wheel)); 7.84 (s, 1 arom. H (wheel)); 8.22 (d, 3J ˆ 7.8, 2 arom. H (wheel)); 8.23
(s, 2 arom. H (wheel)). 13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.9; 25.6; 28.5; 29.5; 31.0; 31.1; 31.2; 31.8; 34.7;
35.0; 35.4; 45.3; 67.7; 68.3; 108.6; 114.2; 114.5; 114.6; 115.7; 126.5; 126.7; 128.5; 128.8; 129.1; 130.9; 131.0; 134.1;
‡
‡
134.3; 135.0; 152.3; 157.6; 158.2; 158.4; 164.7; 165.1. MALDI-TOF-MS: 1706.1 (78, C112H138KN4O8 [M ‡ K ]),
‡
‡
‡
‡
1690.0 (100, [M ‡ Na] ), 998.8 (61, [wheel ‡ K] ), 982.8 (97, [wheel ‡ Na] ), 960.8 (71, [wheel ‡ H] ).
[2]{(1,1'-[Heptane-1,7-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane (12e ¥ 3): Rf 0.23 (CH2Cl2/AcOEt 30 :1). Yield 5% (A), 22% (B).
1H-NMR (400 MHz, C2D2Cl4): 1.20 1.30 (m, 3 CH2 (axle)); 1.25 (s, 4 tBu (axle)); 1.44 (s, 1 tBu (wheel)); 1.63
(br., 2 CH2 (chx, axle)); 1.65 1.84 (m, 6 CH2 (chx)); 1.98 (s, 4 Me (wheel)); 2.01 (s, 4 Me (wheel)); 2.42 (br., 4
CH2 (chx)); 3.73 (t, 3J ˆ 6.8, 2 CH2O (axle)); 4.60 (s, 2 CH2O (axle)); 6.17 (AA' of AA'XX', 3J ˆ 8.2, 4 arom. H
(axle)); 6.55 (XX' of AA'XX', 3J ˆ 8.2, 4 arom. H (axle)); 6.67 (br. s, 4 NH); 7.05 (s, 2 arom. H (axle)); 7.08
(s, 4 arom. H (wheel)); 7.11 (s, 4 arom. H (wheel)); 7.36 (s, 4 arom. H (axle)); 7.69 (s, 1 arom. H (wheel)); 7.71
(t, J ˆ 7.5, 1 arom. H (wheel)); 7.84 (s, 1 arom. H (wheel)); 8.22 (d, 3J ˆ 7.5, 2 arom. H (wheel)); 8.23
(s, 2 arom. H (wheel)). 13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.9; 25.7; 25.8; 28.9; 29.5; 31.0; 31.1; 31.2; 31.8;
34.6; 35.0; 35.8; 45.3; 64.7; 68.5; 108.6; 114.4; 114.6; 114.7; 115.7; 126.5; 126.7; 128.5; 128.8; 129.1; 130.9; 131.0;
‡
‡
134.1; 134.3; 135.0; 152.3; 157.6; 158.2; 164.7, 165.1. MALDI-TOF-MS: 1720.3 (99, C113H140KN4O8 [M ‡ K] ),
‡
‡
‡
‡
1704.3 (100, [M ‡ Na] ), 999.1 (73, [wheel ‡ K] ), 983.1 (84, [wheel ‡ Na] ), 961.1 (72, [wheel ‡ H] ).
[2]{1,1'-[Octane-1,8-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane (12f ¥ 3): Rf 0.24 (CH2Cl2/AcOEt 30 :1). Yield 4% (A), 22% (B).
1H-NMR (400 MHz, C2D2Cl4): 1.20 1.30 (m, 4 CH2 (axle)); 1.25 (s, 4 tBu(axle)); 1.44 (s, 1 tBu (wheel)); 1.60
1.84 (m, 4 CH2 (chx, axle)); 1.97 (s, 4 Me (wheel)); 2.01 (s, 4 Me (wheel)); 2.42 (br. 4 CH2 (chx)); 3.73 (t, 3J ˆ 6.5,
2 CH2O (axle)); 4.60 (s, 2 CH2O (axle)); 6.17 (AA' of AA'XX', 3J ˆ 8.0, 4 arom. H (axle)); 6.55 (XX' of
AA'XX', 3J ˆ 8.0, 4 arom. H (axle)); 6.67 (br. s, 4 NH); 7.05 (s, 2 arom. H (axle)); 7.08 (s, 4 arom. H (wheel));
7.10 (s, 4 arom. H (wheel)); 7.37 (s, 4 arom. H (axle)); 7.69 (s, 1 arom. H (wheel)); 7.71 (t, 3J ˆ 7.6, 1 arom. H
(wheel)); 7.84 (s, 1 arom. H (wheel)); 8.22 (d, 3J ˆ 7.6, 2 arom. H (wheel)); 8.23 (s, 2 arom. H (wheel)).
13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.9; 25.7; 29.0; 29.1; 31.0; 31.1; 31.2; 31.3; 31.8; 34.6; 35.0; 35.4; 45.3; 67.9;
68.6; 108.6; 114.3; 114.7; 115.7; 126.5; 126.7; 128.7; 129.1; 129.3; 130.9; 131.0; 134.1; 134.3; 135.0; 148.8; 152.3;
‡
‡
‡
157.6; 158.3; 164.7; 165.1. MALDI-TOF-MS: 1734.3 (52, C114H142KN4O8 [M ‡ K ]), 1718.3 (100, [M ‡ Na] ),
‡
‡
982.9 (85, [wheel ‡ Na] ), 960.9 (79, [wheel ‡ H] ).
[2]{1,1'-[Nonane-1,9-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane (12g ¥ 3): Rf 0.25 (CH2Cl2/AcOEt 30 :1). Yield 2% (A), 17% (B).
1H-NMR (400 MHz, C2D2Cl4): 1.20 1.30 (m, 5 CH2 (axle)); 1.25 (s, 4 tBu (axle)); 1.44 (s, 1 tBu (wheel)); 1.60
1.84 (m, 8 CH2 (chx, axle)); 1.97 (s, 4 Me (wheel)); 2.01 (s, 4 Me (wheel)); 2.42 (br., 4 CH2 (chx)); 3.74 (t, 3J ˆ
6.5, 2 CH2 (axle)); 4.61 (s, 2 CH2O (axle)); 6.17 (AA' of AA'XX', 3J ˆ 7.8, 4 arom. H (axle)); 6.55 (XX' of
AA'XX', 3J ˆ 7.8, 4 arom. H (axle)); 6.67 (br. s, 4 NH); 7.05 (s, 2 arom. H (axle)); 7.08 (s, 4 arom. H (wheel));
7.10 (s, 4 arom. H (wheel)); 7.37 (s, 4 arom. H (axle)); 7.69 (s, 1 arom. H (wheel)); 7.71 (t, 3J ˆ 7.7, 1 arom. H
(wheel)); 7.84 (s, 1 arom. H (wheel)); 8.22 (d, 3J ˆ 7.7, 2 arom. H (wheel)); 8.23 (s, 2 arom. H (wheel)).

1594
Helvetica Chimica Acta Vol. 85 (2002)
13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.9; 25.8; 29.0; 29.1; 29.3; 31.0; 31.1; 31.2; 31.3; 31.8; 34.6; 35.0; 35.4; 45.3;
68.6; 70.1; 108.6; 114.7; 115.7; 126.5; 126.7; 128.7; 129.1; 130.9; 131.0; 132.1; 134.1; 134.3; 135.0; 148.8; 152.3;
‡
‡
‡
157.6; 158.3; 164.7; 165.1. MALDI-TOF-MS: 1748.3 (38, C115H114KN4O8 [M ‡ K ]), 1732.3 (100, [M ‡ Na] ),
‡
‡
983.1 (99, [wheel ‡ Na] ), 961.0 (92, [wheel ‡ H] ).
[2]{1,1'-[Decane-1,10-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
21.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane (12h ¥ 3): Rf 0.26 (CH2Cl2/AcOEt 30 :1). Yield 4% (A), 21% (B).
1H-NMR (400 MHz, C2D2Cl4): 1.20 1.30 (m, 4 Me (axle)); 1.25 (s, 4 tBu (axle)); 1.44 (s, 1 tBu (wheel)); 1.60
1.84 (m, 8 CH2 (chx, axle)); 1.97 (s, 4 Me (wheel)); 2.00 (s, 4 Me (wheel)); 2.42 (br. 4 CH2 (chx)); 3.74 (t, 3J ˆ 6.6,
2 CH2O (axle)); 4.61 (s, 2 CH2O (axle)); 6.17 (AA' of AA'XX', 3J ˆ 7.4, 4 arom. H (axle)); 6.55 (XX' of
AA'XX', 3J ˆ 7.4, 4 arom. H (axle)); 6.67 (br. s, 4 NH); 7.05 (s, 2 arom. H (axle)); 7.08 (s, 4 arom. H (wheel));
7.10 (s, 4 arom. H (wheel)); 7.37 (s, 4 arom. H (axle)); 7.69 (s, 1 arom. H (wheel)); 7.71 (t, 3J ˆ 7.7, 1 arom. H
(wheel)); 7.85 (s, 1 arom. H (wheel)); 8.22 (d, 3J ˆ 7.7, 2 arom. H (wheel)); 8.23 (s, 2 arom. H (wheel)).
13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.9; 25.8; 26.2; 29.0; 29.1; 29.3; 31.0; 31.1; 31.3; 31.8; 34.6; 35.0; 35.4;
45.3; 68.6, 70.1; 108.7; 114.7; 115.7;126.5; 126.7; 128.7; 129.1; 130.9; 131.0; 132.1; 134.1; 134.3; 135.0; 148.7; 152.3;
‡
‡
153.9; 157.6; 158.3; 164.7; 165.1. MALDI-TOF-MS: 1762.2 (30, C116H146KN4O8 [M ‡ K ]), 1746.2 (100, [M ‡
‡
‡
‡
Na] ), 983.2 (54, [wheel ‡ Na] ), 960.5 (39, [wheel ‡ H] ).
[2]{1,1'-[Undecane-1,11-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-bu-
tyl)-5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.2.3.6
.
216.19.221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-
20',1''-cyclohexane]-8',14',26',32'-tetrone}rotaxane (12i ¥ 3): Rf 0.28 (CH2Cl2/AcOEt 30 :1). Yield 5% (A), 24%
1
t
(B). H-NMR (400 MHz, C2D2Cl4): 1.20 1.30 (m, 7 CH2 (axle)); 1.25 (s, 4 tBu (axle)); 1.44 (s, 1 Bu (wheel));
1.60 1.84 (m, 8 CH2 (chx, axle)); 1.97 (s, 4 Me (wheel)); 2.00 (s, 4 Me (wheel)); 2.42 (br. 4 CH2 (chx)); 3.74
(t, 3J ˆ 6.5, 2 CH2O (axle)); 4.61 (s, 2 CH2O (axle)); 6.17 (AA' of AA'XX', 3J ˆ 7.8, 4 arom. H (axle)); 6.55 (XX'
of AA'XX', 3J ˆ 7.8, 4 arom. H (axle)); 6.67 (br. s, 4 NH); 7.05 (s, 2 arom. H (axle)); 7.08 (s, 4 arom. H (wheel));
7.10 (s, 4 arom. H (wheel)); 7.37 (s, 4 arom. H (axle)); 7.69 (s, 1 arom. H (wheel)); 7.72 (t, 3J ˆ 7.7, 1 arom. H
(wheel)); 7.84 (s, 1 arom. H (wheel)); 8.22 (d, 3J ˆ 7.7, 2 arom. H (wheel)); 8.23 (s, 2 arom. H (wheel)).
13C-NMR (100 MHz, C2D2Cl4): 18.6; 22.9; 25.8; 29.0; 29.1; 29.4; 29.5; 31.0; 31.1; 31.2; 31.3; 31.8; 34.6; 35.0;
35.4; 35.8; 45.3; 68.7; 70.1; 108.6; 114.5; 115.7; 126.5; 126.7; 128.7; 129.1; 130.9; 131.0; 132.1; 134.1; 134.3; 135.0;
‡
‡
148.8; 152.3; 157.6; 158.3; 164.7; 165.1. MALDI-TOF-MS: 1776.3 (22, C117H148KN4O8 [M ‡ K ]), 1760.3 (100,
‡
‡
‡
‡
[M ‡ Na] ), 1737.3 (3, [M ‡ H] ), 983.2 (82, [wheel ‡ Na] ), 960.5 (96, [wheel ‡ H] ).
[2]{1,1'[Dodecane-1,12-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene]}-{11'-(tert-bu-
tyl)5',17',23',35',38',40',43',45'-octamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane (12j ¥ 3). Rf 0.29 (CH2Cl2/AcOEt 30 :1). Yield 3% (A), 19% (B).
1H-NMR (400 MHz, C2D2Cl4): 1.20 1.30 (m, 8 CH2 (axle)); 1.25 (s, 4 tBu (axle)); 1.44 (s, 1 tBu (wheel)); 1.60
1.84 (m, 8 CH2 (chx, axle)); 1.98 (s, 4 Me (wheel)); 2.00 (s, 4 Me (wheel)); 2.43 (br., 4 CH2 (chx)); 3.74 (t, 3J ˆ
6.6, 2 CH2O (axle)); 4.61 (s, 2 CH2O (axle)); 6.17 (AA' of AA'XX', 3J ˆ 7.8, 4 arom. H (axle)); 6.54 (XX' of
AA'XX', 3J ˆ 7.8, 4 arom. H (axle)); 6.67 (br. s, 4 NH); 7.05 (s, 2 arom. H (acle)); 7.08 (s, 4 arom. H (wheel));
7.10 (s, 4 arom. H (wheel)); 7.37 (s, 4 arom. H (axle)); 7.69 (s, 1 arom. H (wheel)); 7.72 (t, 3J ˆ 7.8, 1 arom. H
(wheel)); 7.84 (s, 1 arom. H (wheel)); 8.22 (d, 3J ˆ 7.8, 2 arom. H (wheel)); 8.23 (s, 2 arom. H (wheel)).
13C-NMR (100 MHz, C2D2Cl4): 18.5; 22.9; 25.8; 29.0; 29.2; 29.3; 29.4; 31.0; 31.1; 31.2; 31.3; 34.6; 35.0; 35.4; 45.3;
68.6; 70.1; 108.7; 114.7; 115.7; 126.5; 126.7; 128.7; 129.1; 130.9; 131.0; 132.1; 134.1; 134.3; 135.0; 152.3; 157.6;
‡
‡
‡
158.3; 164.7; 165.1. MALDI-TOF-MS: 1790.0 (13, C118H150KN4O8 [M ‡ K ]), 1773.9 (95, [M ‡ Na] ), 1750.9
‡
‡
‡
(5, [M ‡ H] ), 983.2 (83, [wheel ‡ Na] ), 960.5 (100, [wheel ‡ H] ).
[2]{1,1'-[Octane-1,8-diylbis(oxy)]bis[4-{[4-(triphenylmethyl)phenoxy]methyl}benzene]}-{11'-(tert-butyl)-
5',17',23',35',38',40',43',45'-oxtamethyldispiro[cyclohexane-1,2'-[7,15,25,33]tetraazaheptacyclo[32.2.2.23.6.216.19
.
221.24.19.13.127.31]hexatetraconta[3,5,9,11,13(44),16,18,21,23,27,29,31(39),34,36,37,40,42,45]octadecaene-20',1''-cy-
clohexane]-8',14',26',32'-tetrone}rotaxane 14f ¥ 3: Rf 0.29 (CH2Cl2/AcOEt 30 :1). Yield 35% (A). 1H-NMR
(400 MHz, CDCl3): 1.20 1.40 (m, 4 CH2 (axle)); 1.36 (s, 1 tBu (wheel)); 1.50 1.73 (m, 8 CH2 (chx, axle)); 1.97
(s, 4 Me (wheel)); 1.99 (s, 4 Me (wheel)); 2.34 (br. 4 CH2 (chx)); 3.72 (t, 3J ˆ 6.5, 2 CH2O (axle)); 4.61 (s, 2 CH2O
(axle)); 6.17 (AA' of AA'XX', 3J ˆ 7.8, 4 arom. H (axle)); 6.55 (XX' of AA'XX', 3J ˆ 7.8, 4 arom. H (axle)); 6.84
(br. s, 4 NH); 7.01 7.07 (m, 10 arom. H (axle, wheel)); 7.10 7.25 (m, 6 Ph); 7.60 (s, 1 arom. H (wheel)); 7.70
(t, 3J ˆ 7.4, 1 arom. H (wheel)); 7.80 (s, 1 arom. H (wheel)); 8.19 (d, 3J ˆ 7.4, 2 arom. H (wheel)); 8.22
(s, 2 arom. H (wheel)). 13C-NMR (100 MHz, CDCl3): 14.2; 18.8; 21.0; 23.0; 26.0; 29.3; 31.2; 35.4; 35.8; 45.4;

Helvetica Chimica Acta Vol. 85 (2002)
1595
60.4; 64.3; 68.7; 70.2; 113.5; 115.0; 117.2; 121.4; 123.9; 126.0; 126.8; 126.9; 127.0; 128.7; 129.1; 129.3; 131.0; 132.1;
132.4; 134.7; 135.0; 140.1; 146.8; 148.9; 154.3; 156.2; 158.6; 164.9; 165.4. MALDI-TOF-MS: 1995.2 (35,
‡
‡
‡
‡
C137H140KN4O8 [M ‡ K ]), 1978.2 (100, [M ‡ Na] ), 960.5 (98, [wheel ‡ H] ).
Free Axles. The anal. data of 12c, which is formed as the undesired major product in the reaction of 10À ¥ 3
and 9c, is given as representative for the other free axles formed in the rotaxane synthesis.
1,1'-[Pentane-1,5-diylbis(oxy)]bis[4-{[3,5-di(tert-butyl)phenoxy]methyl}benzene] (12c). 1H-NMR
(400 MHz, CDCl3): 1.24 (s, 4 tBu); 1.60 (q, 3J ˆ 6.5, 1 CH2); 1.78 (−q×, J ˆ 6.5, 4 H); 3.93 (t, 3J ˆ 6.5, 2 CH2O);
3
4.90 (s, 2 CH2OAr), 6.76 (s, 4 arom. H (stopper)); 6.83 (AA' of AA'XX', 3J ˆ 8.7, 4 arom. H); 6.96 (s, 2 arom. H
(stopper)); 7.29 (XX' of AA'XX', 3J ˆ 8.7, 4 arom. H. 13C-NMR (100 MHz, CDCl3): 159.0; 158.6; 152.2; 129.5;
‡
‡
129.4; 115.1; 114.7; 109.2; 69.8; 67.9; 35.0; 31.5; 29.1; 22.8. FAB-MS: 691 (15, C47H63O4 [M À H ]), 487 (100,
‡
‡
‡
‡
[M À OC6H3 À tBu2] . MALDI-TOF-MS: 731 (29, C47H64KO4 [M ‡ K ]), 715 (72, [M ‡ Na] ), 691 (8, [M À
‡
t
‡
H] ), 467 (100, [M À OC6H3 À Bu2] ).
REFERENCES
[1] G. Schill, −Catenanes, Rotaxanes and Knots×, Academic Press, New York, 1971; C. O. Dietrich-Buchecker,
J.-P. Sauvage, Chem. Rev. 1987, 87, 795; J.-P. Sauvage, Acc. Chem. Res. 1990, 23, 319; S. Anderson, H. L.
Anderson, J. K. M. Sanders, Acc. Chem. Res. 1993, 26, 469; R. Hoss, F. Vˆgtle, Angew. Chem. 1994, 106,
389; Angew. Chem., Int. Ed. 1994, 33, 375; D. A. Amabilino, J. F. Stoddart, Chem. Rev. 1995, 95, 2725; J.-C.
Chambron, C. O. Dietrich-Buchecker, V. Heitz, J.-F. Nierengarten, J.-P. Sauvage, C. Pascard, J. Guilhem,
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Received December 17, 2001