One template, multiple rings: Controlled iterative addition of macrocycles onto a single binding site rotaxane thread

Article abstract of DOI:10.1002/anie.200700933

One for all: The iteration of three simple steps - complexation, macrocyclization, and demetalation - enables the synthesis of multi-ring rotaxanes with only one template site (see picture). This efficient and effective strategy enables both the number and the order in which macrocycles are assembled onto a thread to be controlled with unprecedented precision. (Figure Presented)

Full text of DOI:10.1002/anie.200700933

Angewandte
Chemie
DOI: 10.1002/anie.200700933
Rotaxane Synthesis
One Template, Multiple Rings: Controlled Iterative Addition of
Macrocycles onto a Single Binding Site Rotaxane Thread**
Anne-Marie L. Fuller, David A. Leigh,* and Paul J. Lusby
Dedicated to Sir J. Fraser Stoddart on the occasion of his 65th birthday
The introduction[1] and subsequent spectacular growth[2–8] of
template strategies[2] to molecules with multiple mechanically
interlocked components (rotaxanes,[3,4,8] catenanes,[5,6,8] and
Borromean rings[7]) has revolutionized approaches to their
synthesis. However,despite the many different template
systems and innovative assembly processes developed thus
far,a feature common to all current methods is that they each
employ at least one binding site per macrocycle,that is,a
minimum of nÀ1 templates per n interlocked components.
Here we describe a strategy (Figure 1) for assembling multi-
tially forming rings of type H2L2 to iteratively[8b] generate [2]-,
[3]-,and [4]rotaxanes. Overcoming the restriction of only one
ring per template unit—especially the ability to re-utilize the
template despite the proximity of a previously cyclized
component—should aid the synthesis of increasingly complex
higher order interlocked assemblies (for example,defined
sequences of different rings on a molecular strand).
The single template site iterative assembly of multiple ring
rotaxanes utilizes a square-planar geometry PdII-based “clip-
ping” methodology previously developed[9] as a “classical”
(that is,one macrocycle per binding site) template synthesis of
rotaxanes and catenanes. The metal atom is first bound to a
tridentate 2,6-pyridinedicarboxamide ligand (significantly,
this involves deprotonation of the ligand amide groups[9]).
The resulting complex [L3Pd(CH3CN)][9] is coordinated to a
monodentate pyridine unit on a thread such that subsequent
macrocyclization by ring-closing metathesis (RCM) occurs
around the thread to generate an interlocked architecture.[10]
The key to extending this protocol so that further ligands can
be cyclized around the template after the first is decomplexed,
is the observation that whilst [L3Pd(CH3CN)] will readily
exchange its labile coordinated acetonitrile molecule for a
pyridine unit (see Scheme 1,step a),it does not undergo
tridentate ligand exchange with protonated (that is,metal-
free) versions of the 2,6-pyridinedicarboxamide system (for
Figure 1. An iterative [n]rotaxane synthesis utilizing a single template
unit (shown in purple) and the repetition of three simple steps:
a) complexation of an acyclic ligand (shown in light blue) to the
template site; b) macrocyclization; c) demetalation.
example,H L4 and H2L5; Scheme 1,steps d and g). Thus,a
2
pyridine group on a thread can repetitively be used to replace
acetonitrile ligands of [L3Pd(CH3CN)],with the resulting
complexes then being macrocyclized one at a time.
To demonstrate the effectiveness of this strategy in a
multi-ring rotaxane synthesis,a suitable thread L1 was
prepared (see the Supporting Information) with a single
pyridine unit as the only potential template site and sufficient
space—provided by a C11 alkyl chain—between the stoppers
to accommodate several macrocycles. As anticipated,stirring
L1 with [L3Pd(CH3CN)] in dichloromethane resulted in rapid
formation of [L3PdL1] (92%,Scheme 1,step a). Macrocy-
clization with the Grubbs first-generation RCM catalyst and
subsequent hydrogenation[11] gave the saturated palladium
[2]rotaxane [L4Pd] (72%,Scheme 1,step b). Treatment with
potassium cyanide (Scheme 1,step c) then afforded the
metal-free [2]rotaxane H2L4 in 62% overall yield for the
first iterative cycle.
ring rotaxanes in which just a single ligation site is used to clip
on as many macrocycles as required (and the length of the
thread will permit),through the repetition of three simple
steps. The method (Scheme 1) involves the repetitive coordi-
nation and macrocyclization of a tridentate ligand for
palladium about a stoppered molecular thread (L1),sequen-
[*] A.-M. L. Fuller, Prof. D. A. Leigh, Dr. P. J. Lusby
School of Chemistry
University of Edinburgh
The King’s Buildings, West Mains Road, Edinburgh EH9 3JJ (UK)
Fax: (+44)131-650-6453
E-mail: david.leigh@ed.ac.uk
Homepage: http://www.catenane.net
1
A comparison of the room-temperature H NMR spec-
[**] We thank Dr. D. B. Walker for many useful discussions. This work
was supported by the Royal Society, the EU project STAG, and the
EPSRC.
trum of H2L4 in CD2Cl2 (Figure 2c) with that of the free
components macrocycle H2L2 and thread L1 (Figure 1a and
b,respectively) confirms the interlocked nature of the
product. The most significant differences in the spectra are
Supporting information for this article is available on the WWW
under http://www.angewandte.org or fromthe author.
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Scheme 1. The controlled iterative synthesis of [2]-, [3]-, and [4]rotaxanes H2L4, H2L5, and H2L6. CPK models confirm that the threaded rings
cannot pass through the cavities of each other and so the color of each fragment of a structure reflects its origin in the synthetic sequence.
a) [L3Pd(CH3CN)], CH2Cl2, 5 h, RT, 92%; b) 1. Grubbs catalyst (0.12 equiv), CH2Cl2; 2. ortho-nitrobenzenesulfonylhydrazide (NBSH), Et3N, CH2Cl2,
72% (over 2 steps); c) KCN, CH2Cl2, MeOH, 94%; d) [L3Pd(CH3CN)], CH2Cl2, 5 h, RT, 96%; e) 1. Grubbs catalyst (0.12 equiv), CH2Cl2; 2. NBSH,
Et3N, CH2Cl2, 84% (over 2 steps); f) KCN, CH2Cl2, MeOH, 98%; g) method A: [L3Pd(CH3CN)], CH2Cl2, 3 days, RT, [L3PdH2L5] 51%, iso-
[L3PdH2L5] 37%. Method B: [L3Pd(CH3CN)] (3 equiv), CH2Cl2, D, 7 days, [L3PdH2L5] 81%, iso-[L3PdH2L5] 5%; h) 1. Grubbs catalyst (0.12 equiv),
CH2Cl2; 2. NBSH, Et3N, CH2Cl2; 3. KCN, CH2Cl2, MeOH, 70% (over 3 steps) i) 1. Grubbs catalyst (0.12 equiv), CH2Cl2; 2. NBSH, Et3N, CH2Cl2,
87% (over 2 steps); j) KCN, CH2Cl2, MeOH, 97%.
for the signals of the methylene protons adjacent to the
pyridine group of the thread (Hc and Hg),which are shifted,
particularly that of Hc,upfield in the spectrum of the
[2]rotaxane. The macrocycle phenyl resonances (HE1 and
HF1) are also shielded in the [2]rotaxane while the amide
protons (HC1) move 1.3 ppm downfield,which is indicative of
intercomponent hydrogen bonding with the pyridine unit.[12]
However,small upfield shifts in nearly all the axle signals in
the rotaxane,including the alkyl region,show that this
interaction is rather weak and the macrocycle is able to access
the full length of the thread in CD2Cl2.
of H2L4 to give [L3PdH2L4] (Scheme 1,step d) proceeds in
96% yield in 5 h with no trace of transmetalation to the
1
rotaxane macrocycle. Comparison of the H NMR spectrum
of [L3PdH2L4] in CD2Cl2 (Figure 3b) with that of [L3PdL1]
(Figure 3a) indicates that the displaced macrocycle in the
[2]rotaxane spends a significant amount of time over the ether
unit furthest from the Pd coordination sphere (1.2 ppm
upfield shift of the methyleneoxy resonance of the thread
Hm),presumably at least in part as a result of hydrogen
bonding between the amide and oxygen atom of the ether.[13]
The 1H NMR spectrum of the demetalated [3]rotaxane H2L5
in CD2Cl2 is shown in Figure 2d. The occurrence of the amide
signals at d = 9.4 and 8.6 ppm (HC2 and HC1) suggest that the
hydrogen-bonding interaction between the amide group and
the pyridine ring is appreciably stronger than that between
the amide and ether groups.[12,13]
For the second iterative cycle,repetition of the three steps
(complexation,macrocyclization,and
demetalation,
Scheme 1,steps d–f) starting from [2]rotaxane H 2L4 smoothly
afforded [3]rotaxane H2L5 in 79% overall yield. The crucial
complexation of [L3Pd(CH3CN)] to the free pyridine group
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method A). However,the reaction proved extremely sluggish
using the conditions previously employed (CH2Cl2,293 K),
and after three days the product mixture was separated by
column chromatography to give,somewhat unexpectedly,two
new kinetically stable products in a ratio of 2:3. Mass
spectrometry suggested that the products were isomers of
[L3PdH2L5] (Scheme 1),in which the two macrocycles are
restricted to different regions of the thread by coordination of
[L3Pd] to the pyridine unit. The major product was assigned
1
by H NMR spectroscopy as isomer [L3PdH2L5]. Its spec-
trum (Figure 3c) shows increased shielding of the alkyl region
with respect to the similarly derivatized [2]rotaxane
[L3PdH2L4] (Figure 3b),which suggests that both macro-
cycles are located over the C11 region of the thread. In
contrast,the 1H NMR spectrum (Figure 3d) of the minor
isomer showed no increase in the shielding of the alkyl region
relative to [L3PdH2L4]. Rather,significant shifts of the
thread methyleneoxy (Hc) and stopper protons Ha and He
occur,which indicates that this isomer is iso-[L3PdH2L5],in
which the two macrocycles are separated by the coordinated
{L3Pd} unit.
Whilst the formation of this second isomer appears
surprising given the steric demands of the macrocycle and
the very limited space available between the pyridine ligation
site and the closest bulky stopper,it presumably reflects the
fact that an ether oxygen atom is available on that part of the
thread to which one of the two amide macrocycles can spend
significant time hydrogen bonding. Complexation of [L3Pd]
to the pyridine unit traps that proportion of macrocycles in
that region of the thread and the kinetic stability of the
pyridine–palladium bond inhibits equilibration to the less
sterically hindered isomer. In agreement with this ration-
alization,carrying out the reaction at reflux for 7 days
(Scheme 1,step g,method B) to induce some reversibility in
the formation of the pyridine–palladium bond gave 81% of
[L3PdH2L5] with only a small amount of the minor isomer.
The final macrocyclization and demetalation steps to give
[4]rotaxane H2L6 could be carried out on either the single
isomer [L3PdH2L5] (Scheme 1,steps i and j) or on the
mixture of [L3PdH2L5]/iso-[L3PdH2L5] isomers (Scheme 1,
step h). The [4]rotaxane obtained from these reactions—in
both cases single species—had identical physical properties
and indistinguishable 1H NMR spectra (Figure 2e),again
supporting the structural assignments of [L3PdH2L5] and iso-
[L3PdH2L5]. The 1H NMR spectrum of H2L6 in CD2Cl2
(Figure 2e) shows three sets of amide signals,and further
shielding of both the C11 alkyl chain of the thread and in
particular the methyleneoxy resonances (Hc, Hg, Hh). The
overall yield for the iterative cycle to add the third ring to
generate the [4]rotaxane is a pleasing 68% (by way of single
isomer [L3PdH2L5]).
Figure 2. 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of the metal-free
rotaxanes and their non-interlocked components. a) macrocycle H2L2;
b) thread L1; c) [2]rotaxane H2L4; d) [3]rotaxane H2L5; e) [4]rotaxane
H2L6. The italicized letters and numbers refer to the assignments in
Scheme 1 and the component sequences indicated in the schematic
representations.
Figure 3. 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of the coordina-
tion complexes of [L3Pd] with the thread, [2]rotaxane, and [3]rotaxane.
a) [L3PdL1]; b) [L3PdH2L4]; c) [L3PdH2L5]; d) iso-[L3PdH2L5]. The itali-
cized letters and numbers refer to the assignments in Scheme 1 and
the component sequences indicated in the schematic representations.
In conclusion,we have described methodology for pre-
paring multi-ring rotaxanes through the iterative addition of
macrocycles to a rotaxane thread bearing a single ligation site.
By using this efficient and effective strategy,both the number
and the order in which macrocycles are assembled onto a
thread can be controlled with unprecedented precision.
The final iterative cycle commenced with the reaction of
[3]rotaxane H2L5 with [L3Pd(CH3CN)] (Scheme 1,step g,
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Communications
Bogdan,Y. Rudzevich,M. O. Vysotsky,V. Böhmer,
Chem.
Experimental Section
Commun. 2006,2941 – 2952; m) M. S. Vickers,P. D. Beer, Chem.
Soc. Rev. 2007, 36,211 – 225; n) S. J. Loeb, Chem. Soc. Rev. 2007,
36,226 – 235.
General procedure for the iterative synthesis of an [n]rotaxane from
an [nÀ1]rotaxane or thread: a) Complexation: A solution of the
metal-free 2,6-disubstituted pyridine ligand (L1, H2L4,or H 2L5,0.1–
2.0 mmol) and [L3Pd(CH3CN)] (1 equiv for L1, H2L4; 3 equiv for
H2L5) in anhydrous dichloromethane (30 mL) was stirred for 5 h at
room temperature (7 days at reflux for H2L5) under an atmosphere of
nitrogen. The mixture was then concentrated under reduced pressure
and the crude residue purified by column chromatography to yield the
corresponding complex [L3PdL1] (92%),[ L3PdH2L4] (96%),or
[L3PdH2L5] (81%). b) Macrocyclization: The complex obtained
from (a) was dissolved in anhydrous dichloromethane (200 mL for
1 mmol of substrate) and added via a double-ended needle to a
solution of the first-generation Grubbs catalyst (0.12 equiv) in
anhydrous dichloromethane (850 mL per mmol) under an atmos-
phere of nitrogen. The solution was stirred at room temperature for
18 h,after which it was concentrated under reduced pressure,and the
crude residue subjected to column chromatography to yield the
corresponding unsaturated olefin rotaxane–metal complex. This was
dissolved in dichloromethane (12 mL for 1 mmol of substrate) and
then NBSH (8.0 equiv) and triethylamine (10 equiv) added. The
suspension was then stirred overnight. The resultant orange/brown
solution was washed with sodium bicarbonate (3 ” 75 mL) and the
organic layers combined and concentrated to give the saturated
rotaxane–metal complex [L4Pd] (72% over two steps),[ L5Pd] (84%
over two steps),or L6Pd (87% over two steps). c) Demetalation: A
solution of the rotaxane–metal complex [L4Pd],[ L5Pd],or [ L6Pd]
(typically 0.1–1.0 mmol) in dichloromethane (50 mL) was added to a
solution of potassium cyanide (15 equiv) in methanol (50 mL). The
solution was gently heated until it was colorless,and then the overall
volume reduced to less than 5 mL. The resultant mixture was
dispersed in water (100 mL) and washed with dichloromethane (3 ”
50 mL). The combined organic extracts were washed with further
water (50 mL) and dried over anhydrous magnesium sulfate. After
filtration,the solution was concentrated under reduced pressure to
give the demetalated rotaxane (H2L4 (94%),H L5 (98%),or H L6
[3] For examples of [4]rotaxanes (at least three ring-template sites),
´
see a) P. R. Ashton,R. Ballardini,V. Balzani,M. Belohradsky
M. T. Gandolfi,D. Philp,L. Prodi,F. M. Raymo,M. V. Red-
dington,N. Spencer,J. F. Stoddart,M. Venturi,D. J. Williams, J.
Am. Chem. Soc. 1996, 118,4931 – 4951; b) D. B. Amabilino,P. R.
Ashton,V. Balzani,C. L. Brown,A. Credi,J. M. J. FrØchet,J. W.
Leon,F. M. Raymo,N. Spencer,J. F. Stoddart,M. Venturi,
Am. Chem. Soc. 1996, 118,12012 – 12020; c) T. Dünnwald,R.
Jäger,F. Vögtle, Chem. Eur. J. 1997, 3,2043 – 2051; d) D. Tuncel,
J. H. G. Steinke, Chem. Commun. 2002,496 – 497; e) S. J. Loeb,
D. A. Tramontozzi, Org. Biomol. Chem. 2005, 3,1393 – 1401;
f) F. Arció,T. Chang,S. J. Cantrill,S. I. Khan,J. F. Stoddart,
,
J.
ˇ
Chem. Eur. J. 2005, 11,4655 – 4666; g) W. R. Dichtel,O. S
.
´
Miljanic,J. M. Spruell,J. R. Heath,J. F. Stoddart, J. Am. Chem.
Soc. 2006, 128,10388 – 10390; for multi-ring rotaxane-like
supramolecular complexes,see h) H. Sleiman,P. Baxter,J.-M.
Lehn,K. Rissanen, J. Chem. Soc. Chem. Commun. 1995,715 –
ˇ
´
716; i) D. B. Amabilino,P. R. Ashton,M. Be lohradsky,F. M.
Raymo,J. F. Stoddart, J. Chem. Soc. Chem. Commun. 1995,751 –
753; j) D. B. Amabilino,M. Asakawa,P. R. Ashton,R. Ballar-
ˇ
´
dini,V. Balzani,M. Be lohradsky,A. Credi,M. Higuchi,F. M.
Raymo,T. Shimizu,J. F. Stoddart,M. Venturi,K. Yase,
Chem. 1998, 22,959 – 972; k) J.-P. Collin,J. Frey,V. Heitz,E.
Sakellariou,J.-P. Sauvage,C. Tock, New J. Chem. 2006, 30,1386 –
1389.
New J.
[4] For higher order rotaxanes (at least n-1 ring-template sites for n
components),see a) N. SolladiØ,J.-C. Chambron,C. O. Dietrich-
Buchecker,J.-P. Sauvage, Angew. Chem. 1996, 108,957 – 960;
Angew. Chem. Int. Ed. Engl. 1996, 35,906 – 909; b) N. SolladiØ,
J.-C. Chambron,J.-P. Sauvage, J. Am. Chem. Soc. 1999, 121,
3684 – 3692; c) N. Watanabe,T. Yagi,N. Kihara,T. Takata,
Chem. Commun. 2002,2720 – 2721; d) D. Tuncel,N. Cindir,U.
Koldemir, J. Inclusion Phenom. Macrocyclic Chem. 2006, 55,
373 – 380; for polyrotaxanes,non-monodispersed systems in
which several or many rings are threaded onto a polymer
chain or a rotaxane monomer are polymerized,see the following
reviews e) A. Harada, Acta. Polymer. 1998, 49,3 – 17; f) T.
Takata,N. Kihara,Y. Furusho, Adv. Polym. Sci. 2004, 171,1 – 75;
g) F. Huang,H. W. Gibson, Prog. Polym. Sci. 2005, 30,982 –
1018; h) G. Wenz; B.-H. Han,A. Müller, Chem. Rev. 2006, 106,
782 – 817.
2
2
(97%). For full experimental details and compound characterization
see the Supporting Information.
Received: March 1,2007
Published online: May 25,2007
Keywords: coordination modes · macrocycles · palladium ·
.
polyrotaxanes · rotaxanes · template synthesis
[5] For examples of [4]catenanes (at least three ring-template sites),
see a) C. O. Dietrich-Buchecker,B. Frommberger,I. Lüer,J.-P
Sauvage,F. Vögtle, Angew. Chem. 1993, 105,1526 – 1529;
Angew. Chem. Int. Ed. Engl. 1993, 32,1434 – 1437; b) D.
[1] a) C. O. Dietrich-Buchecker,J.-P. Kintzinger,J.-P. Sauvage,
Tetrahedron Lett. 1983, 24,5095 – 5098; b) J.-P. Sauvage, Acc.
Chem. Res. 1990, 23,319 – 327.
[2] For reviews which highlight various aspects of template strat-
egies to mechanically interlocked architectures,see a) D. B.
Amabilino,J. F. Stoddart, Chem. Rev. 1995, 95,2725 – 2828;
Whang,K.-M. Park,J. Heo,P. Ashton,K. Kim,
J. Am. Chem.
Soc. 1998, 120,4899 – 4900.
[6] For higher order catenanes (at least nÀ1 ring-template sites for n
components),see a) D. B. Amabilino,P. R. Ashton,A. S. Reder,
N. Spencer,J. F. Stoddart, Angew. Chem. 1994, 106,450 – 453;
Angew. Chem. Int. Ed. Engl. 1994, 33,433 – 437; b) D. B.
Amabilino,P. R. Ashton,C. L. Brown,E. Córdova,L. A.
Godínez,T. T. Goodnow,A. E. Kaifer,S. P. Newton,M.
Pietraszkiewicz,D. Philp,F. M. Raymo,A. S. Reder,M. T.
Rutland,A. M. Z. Slawin,N. Spencer,J. F. Stoddart,D. J.
Williams, J. Am. Chem. Soc. 1995, 117,1271 – 1293; c) D. B.
Amabilino,P. R. Ashton,S. E. Boyd,J. Y. Lee,S. Menzer,J. F.
Stoddart,D. J. Williams, Angew. Chem. 1997, 109,2160 – 2162;
Angew. Chem. Int. Ed. Engl. 1997, 36,2070 – 2072; d) D. B.
Amabilino,P. R. Ashton,V. Balzani,S. E. Boyd,A. Credi,J. Y.
Lee,S. Menzer,J. F. Stoddart,M. Venturi,D. J. Williams, J. Am.
Chem. Soc. 1998, 120,4295 – 4307; e) S.-G. Roh,K.-M. Park,G.-J.
Park,S. Sakamoto,K. Yamaguchi,K. Kim, Angew. Chem. 1999,
b) Molecular Catenanes, Rotaxanes and Knots:
A Journey
Through the World of Molecular Topology (Eds.: J.-P. Sauvage,
C. Dietrich-Buchecker),Wiley-VCH,Weinheim, 1999; c) G. A.
Breault,C. A. Hunter,P. C. Mayers, Tetrahedron 1999, 55,5265 –
5293; d) Templated Organic Synthesis (Eds.: F. Diederich,P. J.
Stang),Wiley-VCH,Weinheim,
Busch, Coord. Chem. Rev. 2000, 200–202,5 – 52; f) L. Raehm,
D. G. Hamilton,J. K. M. Sanders, Synlett 2002,1743 – 1761; g) K.
2000; e) T. J. Hubin,D. H.
´
Kim, Chem. Soc. Rev. 2002, 31,96 – 107; h) F. Aricó,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; i) C. Dietrich-Buchecker,
B. X. Colasson,J.-P. Sauvage, Top. Curr. Chem. 2005, 249,261 –
283; j) E. R. Kay,D. A. Leigh, Top. Curr. Chem. 2005, 262,133 –
177; k) S. J. Loeb, Chem. Commun. 2005,1511 – 1518; l) A.
5018
www.angewandte.org
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Chemie
111,671 – 675; Angew. Chem. Int. Ed. 1999, 38,637 – 641; f) P. R.
Ashton,V. Baldoni,V. Balzani,C. G. Claessens,A. Credi,
H. D. A. Hoffmann,F. M. Raymo,J. F. Stoddart,M. Venturi,
A. J. P. White,D. J. Williams, Eur. J. Org. Chem. 2000,1121 –
1130; g) K.-M. Park,S.-Y Kim,J. Heo,D. Whang,S. Sakamoto,
K. Yamaguchi,K. Kim, J. Am. Chem. Soc. 2002, 124,2140 – 2147.
[7] a) 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;
b) K. S. Chichak,A. J. Peters,S. J. Cantrill,J. F Stoddart, J. Org.
Chem. 2005, 70,7956 – 7962; c) S. J. Cantrill,K. S. Chichak,A. J.
Peters,J. F. Stoddart, Acc. Chem. Res. 2005, 38, 1 – 9; d) K. S.
3330; e) C. Gaeta,M. O. Vysotsky,A. Bogdan,V. Böhmer,
Am. Chem. Soc. 2005, 127,13136 – 13137; f) X.-Z. Zhu,C.-F.
Chen, J. Am. Chem. Soc. 2005, 127,13158 – 13159; g) O.
Molokanova,M. O. Vysotsky,Y. Cao,I. Thondorf,V. Böhmer,
Angew. Chem. 2006, 118,8220 – 8224; Angew. Chem. Int. Ed.
2006, 45,8051 – 8055.
J.
[9] a) A.-M. Fuller,D. A. Leigh,P. J. Lusby,I. D. H. Oswald,S.
Parsons,D. B. Walker, Angew. Chem. 2004, 116,4004 – 4008;
Angew. Chem. Int. Ed. 2004, 43,3914 – 3918; b) A.-M. L. Fuller,
D. A. Leigh,P. J. Lusby,A. M. Z. Slawin,D. B. Walker, J. Am.
Chem. Soc. 2005, 127,12612 – 12619; c) D. A. Leigh,P. J. Lusby,
A. M. Z. Slawin,D. B. Walker, Chem. Commun. 2005,4919 –
4921.
Chichak,S. J. Cantrill,J. F. Stoddart,
Chem. Commun. 2005,
3391 – 3393; e) A. J. Peters,K. S. Chichak,S. J. Cantrill,J. F.
Stoddart, Chem. Commun. 2005,3394 – 3396; f) C. D. Pentecost,
A. J. Peters,K. S. Chichak,G. W. V. Cave,S. J. Cantrill,J. F.
Stoddart, Angew. Chem. 2006, 118,4205 – 4210; Angew. Chem.
Int. Ed. 2006, 45,4099 – 4104.
[10] A “threading-and-stoppering” procedure based on
template has also been described: Y. Furusho,T. Matsuyama,
a
PdII
T. Takata,T,MoriuchiT, . Hirao,
9593 – 9597.
Tetrahedron Lett. 2004, 45,
[8] Higher interlocked oligomers,up to a [7]catenane [a) F. Bitsch,
C. O. Dietrich-Buchecker,A.-K. KhØmiss,J.-P. Sauvage,A.
Van Dorsselaer, J. Am. Chem. Soc. 1991, 113,4023 – 4025] and a
[6]rotaxane [b) A. H. Parham,R. Schmeider,F. Vögtle, Synlett
1999,1887 – 1890],have been detected in various reaction
mixtures by mass spectrometry. The latter example,which
features six template sites on the thread for up to five macro-
cycles,was termed an “iterative rotaxane synthesis” by the
authors but is essentially a standard one-pot “threading-and-
stoppering” strategy; for high order catenanes and rotaxanes in
which the threaded rings are covalently connected together,see
c) L. Wang,M. O. Vysotsky,A. Bogdan,M. Bolte,V. Böhmer,
Science 2004, 304,1312 – 1314; d) A. Bogdan,M. O. Vysotsky,T.
Ikai,Y. Okamoto,V. Böhmer, Chem. Eur. J. 2004, 10,3324 –
[11] The L1 component proved unstable to hydrogenation using H2
over Pd/C,although this method had been previously employed
successfully on PdII-coordinated interlocked architectures.[9]
Various alternative reagents and conditions were investigated
of which ortho-nitrobenzenesulfonylhydrazide (NBSH) proved
the most efficacious [see A. G. Myers,B. Zheng,M. Movassaghi,
J. Org. Chem. 1997, 62,7507].
[12] D. A. Leigh,P. J. Lusby,A. M. Z. Slawin,D. B. Walker, Angew.
Chem. 2005, 117,4633 – 4640; Angew. Chem. Int. Ed. 2005, 44,
4557 – 4564.
[13] J. S. Hannam,S. M. Lacy,D. A. Leigh,C. G. Saiz,A. M. Z.
Slawin,S. G. Stitchell, Angew. Chem. 2004, 116,3322 – 3326;
Angew. Chem. Int. Ed. 2004, 43,3260 – 3264.
Angew. Chem. Int. Ed. 2007, 46, 5015 –5019
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
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