Quantitative formation of [2]catenanes using copper(I) and palladium(II) as templating and assembling centers: The entwining route and the threading approach

Article abstract of DOI:10.1021/ja021370l

Transition metal-mediated templating and self-assembly have shown powerful potentials for the synthesis of interlocked molecules. These two strategies were combined in designing and preparing a new type of coordination catenanes incorporating Cu(I) and Pd(II) metal centers. The ligand designed here contains a phenanthroline core and pyridine sidearms (compound 1). Using this phenanthroline-pyridine conjugated ligand, two approaches were examined, which were shown to be surprisingly efficient for the catenane synthesis: the entwining route (entwining of two ligands around Cu(I) followed by Pd(II) clipping) and the threading approach (Cu(I)-templated threading of a cyclic ligand on an acyclic ligand followed by the PD(II) clipping of the second ring). In the former method, stepwise treatment of 1 with Cu(CH₃CN)₄PF₆ (templating center) and enPd(NO₃)₂ (assembling center) gives rise to the quantitative formation of CuPd₂ catenane 18. In the latter method, Cu(I) templates the threading of phenanthroline-containing macrocycle 2 on ligand 1, which is followed by Pd(II) clipping to give hetero catenane 20. In both approaches, the formation of catenanes is convincing thanks to the strong templating effect of Cu(I), while the ring closure steps are efficiently furnished by Pd(II)-directed self-assembly.

Full text of DOI:10.1021/ja021370l

Published on Web 04/18/2003
Quantitative Formation of [2]Catenanes Using Copper(I) and
Palladium(II) as Templating and Assembling Centers: The
Entwining Route and the Threading Approach
Christiane Dietrich-Buchecker,*,† Benoˆıt Colasson,† Makoto Fujita,*,‡,§ Akiko Hori,‡,|
Neri Geum,# Shigeru Sakamoto, Kentaro Yamaguchi, and Jean-Pierre Sauvage*,†
Contribution from the Laboratoire de Chimie Organo-Mine´rale, UMR 7513 du CNRS,
UniVersite´ Louis Pasteur, Faculte´ de Chimie, 4, Rue Blaise Pascal, 67070 Strasbourg Cedex,
France, Department of Applied Chemistry, Graduate School of Engineering, The UniVersity of
Tokyo, and CREST, Japan Science and Technology Corporation (JST), Genesis Research
Institute, Inc., 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan, Dankook UniVersity, 8
Hannam-dong, Yongsan-ku, Seoul 140-714, Korea, and Chemical Analysis Center, Chiba
UniVersity, Yayoicho, Inage-ku, Chiba 263-8522, Japan
Received November 21, 2002; E-mail: sauvage@chimie.u-strasbg.fr.
Abstract: Transition metal-mediated templating and self-assembly have shown powerful potentials for the
synthesis of interlocked molecules. These two strategies were combined in designing and preparing a
new type of coordination catenanes incorporating Cu(I) and Pd(II) metal centers. The ligand designed here
contains a phenanthroline core and pyridine sidearms (compound 1). Using this phenanthroline-pyridine
conjugated ligand, two approaches were examined, which were shown to be surprisingly efficient for the
catenane synthesis: the entwining route (entwining of two ligands around Cu(I) followed by Pd(II) clipping)
and the threading approach (Cu(I)-templated threading of a cyclic ligand on an acyclic ligand followed by
the Pd(II) clipping of the second ring). In the former method, stepwise treatment of 1 with Cu(CH3CN)4PF6
(templating center) and enPd(NO3)2 (assembling center) gives rise to the quantitative formation of CuPd2
catenane 18. In the latter method, Cu(I) templates the threading of phenanthroline-containing macrocycle
2 on ligand 1, which is followed by Pd(II) clipping to give hetero catenane 20. In both approaches, the
formation of catenanes is convincing thanks to the strong templating effect of Cu(I), while the ring closure
steps are efficiently furnished by Pd(II)-directed self-assembly.
Introduction
Catenanes have mostly been restricted to organic chemistry
since, traditionally, their backbones consisted of covalent bonds
(usually C-C, C-O, or C-N bonds). In addition, these species
were normally not obtained under thermodynamic control: the
cyclization reaction(s) representing the last step(s) had no
reversibility character.
Interlocking ring systems (catenanes) and threaded rings
(rotaxanes) are presently attracting much attention in relation
to their topological, electronic, and dynamic properties.1-3 In
particular, they represent promising prototypes of switches,
machines, and motors at the molecular level.4-7
The situation changed dramatically when catenanes started
to be prepared using reversible reactions as ring-closing steps.
Coordination chemistry bonds such as Pd(II)-N bonds (N being
a pyridine nitrogen atom) turned out to be particularly well
adapted to the formation of cyclic structures and, in particular,
interlocking rings, under thermodynamic control.8 Organic
chemistry bonds whose formation and cleavage is reversible
have also been used to generate catenanes or rotaxanes.9
† Universite´ Louis Pasteur.
‡ The University of Tokyo.
§ CREST, Japan Science and Technology Corporation (JST).
| Genesis Research Institute, Inc.
# Dankook University.
Chemical Analysis Center, Chiba University.
(1) For early work, see: Schill, G. Catenanes, Rotaxanes and Knots; Academic
Press: New York, 1971.
(2) Sauvage, J.-P., Dietrich-Buchecker, C. Eds. Molecular Catenanes, Rotax-
anes and Knots; Wiley-VCH: Weinheim, 1999.
Transition metals have been incorporated as constitutive
elements in various types of catenanes.10 Another case relies
(3) For recent review articles see: (a) Amabilino, D. B.; Stoddart, J. F. Chem.
ReV. 1995, 95, 2725. (b) Chambron, J.-C.; Dietrich-Buchecker C.; Sauvage,
J.-P. In Templating Self-Assembly and Self-Organisation; Sauvage, J.-P.,
Hosseini, M. W., Eds. ComprehensiVe Supramolecular Chemistry 9;
Pergamon: New York, 1996; pp 43-83. (c) Breault, G. A.; Hunter, C. A.;
Mayers, P. C. Tetrahedron 1999, 55, 5265. (d) Vo¨gtle, F.; Du¨nnwald, T.;
Schmidt, T. Acc. Chem. Res. 1996, 29, 451.
on a Grignard reagent, which allowed the preparation of a Mg2+
-
incorporating catenane.11 Of course, transition metals have also
(4) Collin, J.-P.; Dietrich-Buchecker, C.; Gavin˜a, P.; Jimenez-Molero, M. C.;
Sauvage, J.-P. Acc. Chem. Res. 2001, 34, special issue on Molecular
Machines.
(5) Structure & Bonding, special issue on Molecular Machines and Motors;
Sauvage, J.-P. Ed.; Springer: Berlin, 2001; Vol. 99.
(6) Feringa, B. L. Molecular Switches; Wiley-VCH: Weinheim, 2001.
(7) Collier, C. P.; Mattersteig, G.; Wong, E. W.; Luo, Y.; Beverly, K.; Sampaio,
J.; Raymo, F. M.; Stoddart, J. F.; Heath, J. R. Science 2000, 289, 1172.
(8) (a) Fujita, M.; Ibukuro, F.; Hagihara, H.; Ogura, K. Nature 1994, 367,
720. (b) Hori, A.; Kumazawa, K.; Kusukawa, T.; Chand, D. K.; Fujita,
M.; Sakamoto, S.; Yamaguchi, K. Chem. Eur. J. 2001, 7, 4142, and
references therein.
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J. AM. CHEM. SOC. 2003, 125, 5717-5725
5717

A R T I C L E S
Dietrich-Buchecker et al.
Figure 1. Two prototypes of catenanes, prepared by the Strasbourg group
(a) or the Chiba-Okazaki-Nagoya-Tokyo team (b).
played another important role in catenane chemistry. They
afforded particularly efficient templates, allowing high yields
of the precursors.12 Copper(I) has been used extensively to
gather and orient the various organic fragments to be incorpo-
rated in the catenane. Very generally, the last cyclization step
leading to the desired interlocking ring system used to be a
classical nonreversible reaction (Williamson ether formation
reaction or Glaser-Egglinton oxidative coupling of terminal
acetylenic groups). The only exception of a reversible organic
reaction used in conjunction with transition metal-templated
synthesis of catenanes makes use of the ring-closing metathesis
of olefins.13
The present report describes the use of transition metal centers
both as elements of the rings and as template. This approach
relies on previous work from our two groups (“template”12 and
“self-assembly”14), and it involves thermodynamic control for
both processes: (i) formation of the precursor to be cyclized
and (ii) ring-closing reaction. Preliminary data have been briefly
described as communications.15 We will focus in the present
paper on the synthesis of [2]catenanes constructed around
copper(I) complexes used as scaffolds and cyclized using
palladium(II).
Figure 2. The entwining approach: the two organic fragments (1) are first
coordinated to copper(I) so as to afford an entwined complex. The double
ring closing step is performed using palladium(II) as a “clipping” metal
center.
example of a catenane prepared using a transition metal center
as template.12 It consists of two interlocking 30-membered rings.
The 4-palladium compound (b) is the first catenane obtained
via self-assembly. It is formed quantitatively under thermo-
dynamic control,8 and it also consists of two interlocking 30-
membered rings.
We have previously prepared a doubly interlocking [2]-
catenane using copper(I) as a gathering metal, able to induce
the entwining of two organic fragments, followed by a complex
cyclization step with palladium(II).15 Unexpectedly, the simple
catenane was not obtained because the organic ligands were
too short to afford rings incorporating single palladium(II)
atoms. The dimeric compound, i.e., the 4-crossing [2]catenane,
was obtained instead of the simple system, in agreement with
molecular modeling studies that indicated very clearly that the
doubly interlocking compound was the most stable. In the
present work, to minimize ring strain, we used a large organic
ligand, which was expected to afford nonstrained Pd(II)-
containing rings.
Results and Discussion
Design of the Ligands and Strategy. The two prototypical
catenanes synthesized by our groups are represented in Figure
1. The copper(I)-complexed interlocking system (a) is an
(9) (a) Kidd, T. J.; Leigh, D. A.; Wilson, A. J. J. Am. Chem. Soc. 1999, 121,
1599. (b) Furlan, R. L. E.; Otto, S.; Sanders, J. K. M. Proc. Natl. Acad.
Sci. U.S.A. 2002, 99, 4801. (c) Glink, P. T.; Oliva, A. I.; Stoddart, J. F.;
White A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. 2001, 40, 1870. (d)
Cantrill, S. J.; Rowan, S. J.; Stoddart, J. F. Org. Lett. 1999, 1, 1363. (e)
Rowan, S. J.; Stoddart, J. F. Org. Lett. 1999, 1, 1913. (f) Samori, P; Jaˆckel,
F.; U¨ nsal, O¨ .; Godt, A.; Rabe, P. J. Chem. Phys. Chem. 2001, 7, 461. (g)
Simone, D. L.; Swager, T. M. J. Am. Chem. Soc. 2000, 122, 9300. (h)
Watanabe, N.; Yagi, T.; Kihara, N.; Takata, T. Chem. Commun. 2002, 2720.
(i) Korybut-Daszkiewicz, B.; Wieckowska, A.; Bilewicz, R.; Domagala,
S.; Wozniak, K. J. Am. Chem. Soc. 2001, 123, 9356. (j) Du¨rr, H.; Bossmann,
S. Acc. Chem. Res. 2001, 34, 905. (k) Vo¨gtle, F.; Meier, R.; Hoss, R. Angew.
Chem., Int. Ed. Engl. 1992, 31, 1619.
(10) (a) Kim, K. Chem. Soc. ReV. 2002, 31, 96. (b) McArdle, C. P.; Irwin, M.
J.; Jennings, M. C.; Vittal, J. J.; Puddephatt, R. J. Chem. Eur. J. 2002, 8,
723. (c) Padilla-Tosta, M. E.; Fox, O. D.; Drew, M. G. B.; Beer, P. D.
Angew. Chem., Int. Ed. 2001, 40, 4235. (d) Mingos, D. M. P.; Yau, J.;
Menzer, S.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1995, 34, 1894.
(11) Gruter, G.-J. M.; de Kanter, F. J. J.; Markes, P. R.; Nomot, T.; Akkerman,
O. S.; Bickelhaupt, F. J. Am. Chem. Soc. 1993, 115, 12179.
Two distinct strategies have been followed: (i) the “entwin-
ing” strategy, consisting in intertwining the two organic frag-
ments around Cu(I) before closing the rings with Pd(II), and
(ii) the “threading” approach, with relies on the copper(I)-
directed threading of a presynthesized ring by a coordinating
organic fragment, followed by clipping two appended coordinat-
ing groups by Pd(II) so as to form the second ring. The two
strategies and the chemical structures of the organic precursors
used are represented in Figures 2 and 3.
Synthesis of 1a Using the Ullman Reaction. Ligand 1a was
obtained by a double Ullman reaction16 between 4,7-di-n-hexyl-
2,9-bis[4-(4-hydroxyphenyl)phenyl]-1,10-phenanthroline (3)17
and 4-(4-bromophenyl)pyridine (4).18 The latter reaction was
(12) (a) Dietrich-Buchecker, C. O.; Sauvage, J.-P.; Kintzinger, J.-P. Tetrahedron
Lett. 1983, 24, 5095. (b) Dietrich-Buchecker, C. O.; Sauvage, J.-P.; Kern,
J.-M. J. Am. Chem. Soc. 1984, 106, 3043. (c) Dietrich-Buchecker, C. O.;
Sauvage, J.-P. Chem. ReV. 1987, 87, 795.
(13) Mohr, B.; Weck, M.; Sauvage, J.-P.; Grubbs, R. H. Angew. Chem., Int.
Ed. Engl. 1997, 36, 1308.
(14) Fujita, M. Acc. Chem. Res. 1999, 32, 53.
(16) Kalinin, A. V.; Bower, J. F.; Riebel, P.; Snieskus, V. J. Org. Chem. 1999,
64, 2986.
(17) Kern, J.-M.; Sauvage, J.-P.; Weidmann, J.-L.; Armaroli, N.; Flamigni, L.;
Ceroni, P.; Balzani, V. Inorg. Chem. 1997, 36, 5329.
(18) Fujita, M.; Oka, H.; Ogura, K. Tetrahedron Lett. 1995, 36, 5247.
(15) (a) Ibukura, F.; Fujita, M.; Yamaguchi, K.; Sauvage, J.-P. J. Am. Chem.
Soc. 1999, 121, 11014. (b) Dietrich-Buchecker, C. O.; Geum, N.; Hori,
A.; Fujita, M.; Sakamoto, S.; Yamaguchi, K.; Sauvage, J.-P. Chem.
Commun. 2001, 1182.
9
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Quantitative Formation of [2]Catenanes
A R T I C L E S
was treated with p-bromophenyllithium in diethyl ether at 0 °C
to afford the 2-(p-bromophenyl)-1,10-phenanthroline 9 in 82%
yield after hydrolysis and oxidation by MnO2. Phenanthroline
10 was prepared by reacting 9 again with p-bromophenyllithium
in monosubstitution conditions;20 10 was obtained as a white
solid in 88% yield. Finally, 8 was cross-coupled with 10 under
modified Stille conditions21 ([PdCl2(PPh3)2]/LiCl, toluene, 120
°C) to give ligand 1b in 45% yield as a colorless solid.18
Synthesis of 1b Using Carbon-Carbon Bond Formation
via Suzuki-Miyaura Cross-Coupling Reactions. To avoid
the use of toxic Me3SnCl and to improve the overall yield, we
further studied an alternative approach to 1b. Consequently, we
succeeded in replacing the Stille coupling step by Suzuki-
Miyaura coupling reaction with significant increase in chemical
yield. The synthesis of bromide 7 was also slightly modified.
Thus, 4-bromodiphenyl ether (11) was quantitatively converted
to 4-bromo-4′-iododiphenyl ether (12) using iodine monochlo-
ride in refluxing acetic acid.22 By taking avantage of the fact
that lithiation of compound 12 should occur selectively at the
C-I bond, it was treated with 1 equiv of n-BuLi in Et2O in the
presence of TMEDA23 at -78 °C, and the resulting mixture
was quenched with trimethylborate. After hydrolysis, the free
boronic acid was used without any purification in the next step,
which consists of esterification with 2,2-dimethylpropan-1,3-
diol. The boronic ester 13 was obtained in 70% yield. Classical
conditions for a Suzuki-Miyaura cross-coupling reaction ([Pd-
(PPh3)4], Na2CO3 (2 M), in toluene/water at reflux) were used
to react the boronic ester 13 with 4-bromopyridine hydrochloride
(14), which was deprotonated in situ.19 Controlling the duration
of this reaction was very important since after 2 h the reaction
was probably complete, but beyond, the product underwent a
debromination. It also appeared that the C-Br bond of the
pyridine was more reactive than that of the diphenyl ether
moiety. Thus, the 4-bromo-4′-pyridyldiphenyl ether (7) was
obtained in 80% yield. Several attempts were made to synthesize
the 4-boronic-4′-pyridyldiphenyl ether (16): n-BuLi as well as
t-BuLi did not afford satisfactory results. However, the use of
pinacolato-diboron 15 with 7 in the presence of KOAc and a
catalytic amount of [Pd(dppf)]Cl2 (dppf is 1,1′-bis(diphen-
ylphosphino)ferrocene) in dioxane was very efficient, as the
boronic ester 16 was obtained in 95% yield.24 The last step
required the formation of two carbon-carbon bonds. Once
again, classical conditions for Suzuki cross-coupling reaction
were used, leading to 1b in 80% yield on the gram scale.
Synthesis of [2]Catenanes from Three Components: The
Entwining Route. As a common approach, we first examined
the stepwise synthesis of Cu(I)Pd(II) bimetallic catenane 18 from
ligand 1 according to the route of Figure 2, which involves the
entwining of ligand 1 around a Cu(I) templating center followed
by Pd(II)-mediated ring closure (the entwining route). 1H NMR
spectroscopy showed that both steps proceeded very cleanly.
On complexation with Cu(CH3CN)4‚PF6 (0.5 mol equiv), two
Figure 3. The threading approach: the open-chain ligand is threaded
through the ring (2) thanks to the gathering and threading effect of copper-
(I). The single cyclization step with palladium(II) is carried out as in Figure
2.
Scheme 1. Synthesis of Ligand 1a
performed in refluxing toluene in the presence of Cs2CO3 and
Cu(CH3CN)4‚PF6 over 3 days. After demetalation of the crude
reaction mixture with KCN and purification by chromatography
over silica gel, 1a was obtained in 10% yield as a pale yellow
1
glass (Scheme 1). It could be fully characterized by H NMR
and mass spectroscopy.
Synthesis of 1b Using Carbon-Carbon Bond Formation
via Stille Cross-Coupling Reaction. The overall yield in the
synthesis of 1a is limited by the very low yield of the last step
consisting of the Ullman reaction. To avoid this reaction, the
synthesis of 1b was centered around the commercially available
diphenyl ether moiety (Scheme 2). Thus, 4-bromodiphenyl ether
5 was treated with 4-pyridylboronic acid pinacol ester (6, 0.5
equiv to 5) under Suzuki-Miyaura cross-coupling conditions
to give 7 in 56% yield as colorless microcrystals.19 The bromide
7 was converted into stannyl compound 8 in 84% yield by
lithiation (n-BuLi) followed by stannylation (Me3SnCl). Simul-
taneous introduction of the two p-bromophenyl groups in the 2
and 9 positions of the phenanthroline could not be envisaged
due to the presence of reactive bromine in the target compound.
Nevertheless, the difunctionalized phenanthroline 10 could be
obtained in a two-step synthesis that corresponds to two
successive monosubstitution reactions performed with p-bro-
mophenyllithium at low temperature. Thus 1,10-phenanthroline
(20) (a) Dietrich-Buchecker, C. O.; Nierengarten, J.-F.; Sauvage, J.-P.; Armaroli,
N.; Balzani, V.; De Cola, L. J. Am. Chem. Soc. 1993, 115, 11237. (b)
Dietrich-Buchecker, C. O.; Jime´nez, M. C.; Sauvage, J.-P. Tetrahedron
Lett. 1999, 40, 3395. (c) Eisch, J. J.; King, R. B. In Organometallic
Synthesis; Academic Press: New York, 1982; Vol. 2, p 93.
(21) Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508.
(22) (a) Scarborough, H. A. J. Chem. Soc. 1929, 2361. (b) Brewster, R. Q.;
Strain, F. J. Am. Chem. Soc. 1934, 56, 117.
(23) Krattky, P.; Haslinger, U.; Widhalm, M. Monatsh. Chem. 1998, 129, 1319.
(24) Ishiyama, T.; Murata, M.; Miyaura, N. J. Org. Chem. 1995, 60, 7508. (b)
Ishiyama, T.; Itoh, Y.; Kitano, T.; Miyaura, N. Tetrahedron Lett. 1997,
38, 3447.
(19) (a) Miyaura, N.; Yanagi, T.; Suzuki, A. Synth. Commun. 1981, 11, 513.
(b) Miyaura, N.; Suzuki, A. Chem. ReV. 1995, 95, 2457.
9
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A R T I C L E S
Dietrich-Buchecker et al.
Scheme 2. Synthesis of Ligand 1b via Stille Cross-Coupling Reaction
Scheme 3. Synthesis of Ligand 1b via Suzuki-Miyaura Cross-Coupling Reactions
ligands are orthogonally oriented around the Cu(I) center being
magnetically shielded by each other. Experimentally, ligand 1b
was suspended in a DMF solution of the Cu(I) salt (Scheme
4). A clear red solution resulted after 15 min. In 1H NMR, Hm-1
and Ho-1 are positively shielded by the phenanthroline core,
while H3,8 and H4,7 are negatively shielded (Figure 4b), as we
have previously observed in related catenane precursors.25
Pyridine protons (Hm-4 and Ho-4) are missing probably due to
acid-base interaction with (wet) solvent on the NMR time scale.
(25) Dietrich-Buchecker, C. O.; Marnot, P. A.; Sauvage, J.-P.; Kintzinger, J.-
P.; Malte´se, P. New J. Chem. 1984, 8, 573.
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Quantitative Formation of [2]Catenanes
A R T I C L E S
the melting point of complex 17b was relatively low (191-
192 °C), after clipping by Pd(II) ion, 18b was not molten and
decomposed even at 300 °C, indicating the rigid and highly
charged catenane structure.
In addition to satisfactory NMR, CSI-MS (coldspray ioniza-
tion mass spectrometry)26 also supported the structures of 17b
and 18b. For complex 17b, a clear spectrum with an intense
peak at m/z 1708, which corresponds to single charged [17b-
PF6]+, was obtained. CSI-MS of 18b (CH3CN-DMF, 20 mM)
showed predominant peaks for multicharged [(18b-PF6-
(NO3)n)+(dmf)m](n+1)+: e.g., m/z 546.5 [(18b-PF6-(NO3)3)+
(CH3CN)2]4+, 721.6 [18b-PF6-(NO3)2]3+
.
As previously communicated,15b the same strategy was
applied to the synthesis of alkyl chain-attached catenane 18a
from ligand 1a. The catenane precursor 17a was efficiently
obtained by treating ligand 1a with Cu(CH3CN)4‚PF6 (Scheme
4). In contrast to 1b, ligand 1a showed good solubility in DMF,
and the complexation in CH3CN-DMF (1:1) solution im-
mediately completed upon addition of Cu(CH3CN)4‚PF6. The
formation of 17a as a single product was confirmed by NMR
and CSI-MS studies. The proton NMR spectrum of 17a in CD3-
CN-DMF-d7 showed eight signals in the aromatic region.
Again, pyridine protons are too broadened to be observed. A
parent peak at m/z 2046.2 in CSI-MS was assigned as [17a-
PF6]+. [2]Catenane 18a was quantitatively formed by adding 2
equiv of enPd(NO3)2 into the CH3CN-DMF solution of 17a
in the same way as those for the complexation of 18b. This
product was assigned as catenane 18a on the basis of NMR
and CSI-MS studies. CSI-MS of 18a (CH3CN-DMF, 20 mM)
showed predominant peaks for multicharged [(18a-PF6-
(NO3)n)+(dmf)m](n+1)+: e.g., m/z 548.4 [(18a-PF6-(NO3)4)+-
(dmf)5]5+, 646.7 [(18a-PF6-(NO3)3)+(dmf)2]4+, 834.5 [18a-
PF6-(NO3)2]3+ (Figure 5a). From the red reaction solution, 18a
was isolated as red microcrystals by adding a large amount of
diethyl ether (85%). While previous Pd(II)-linked catenanes that
are interlocked through hydrophobic interactions are dissociated
into monomer rings at low concentrations,8a,14 catenane 18a is
considerably stable even at very low concentration (0.005 mM)
because two rings are held by a Cu(I)-templating center. We
note that, even under MS conditions, dissociation of 18a into a
monomeric ring (en(Pd)‚17a3+ species) was not observed,
consistent with the high stability of catenane 18a.
Figure 4. 1H NMR observation for the preparation of catenane 18b via
entwining route (aromatic region, 500 MHz, 25 °C, 10 mM, TMS as an
external standard): (a) ligand 1b in CDCl3; (b) Cu(I) complex 17b from
1b and Cu(CH3CN)4‚PF6 in DMF-d7; (c) [2]catenane 18b from 17b and
enPd(NO3)2 in DMF-d7.
Scheme 4. Synthesis of [2]Catenane and Its Precursor from
Three Components
Synthesis of a Hetero [2]Catenane from Four Compo-
nents: The Threading Approach. We next examined the
synthesis of hetero [2]catenane 20, which consists of a covalent
ring and a Pd(II)-clipped ring. This catenane is prepared by the
“threading approach”, which includes the threading of preformed
macrocycle 227 on ring precursor 1b by Cu(I) templating
followed by the closure of the second ring by Pd(II) clipping
(Scheme 5).
The catenane precursor 19 was obtained by treating ligands
1b and 2 with Cu(CH3CN)4‚PF6 (1:1:1 molar ratio) in DMF (2
mL) (Scheme 5). As expected, the exclusive formation of
threaded precursor 19 was observed by NMR (Figure 6b). The
selective formation of 19 is driven by the impossible homo
complexation of cyclic 2 (i.e., Cu‚(2)2 formation), as well
documented in our previous studies.12 The proton NMR
By adding diethyl ether to the solution, Cu(I) complex 17b was
precipitated in a pure form in 93% yield as a red microcrystalline
solid.
The precursor 17b was subsequently treated with enPd(NO3)2
for the ring-closure step. On complexation, signals are in general
upfield shifted except for Hm-3 and Ho-3, which are confor-
mationally free before complexation but fixed after complexation
at the negative-shielding region of the phenanthroline core of
another ligand (Figure 4c). From the solution, Cu(I)Pd(II)
complex 18b was precipitated as a reddish purple powder in
92% yield by adding a large amount of diethyl ether. Although
(26) Sakamoto, S.; Fujita, M.; Kim, K.; Yamaguchi, K. Tetrahedron 2000, 56,
955. (b) Yamaguchi, K.; Sakamoto, S.; Imamoto, T.; Ishikawa, S. Anal.
Sci. 1999, 15, 1037.
(27) Dietrich-Buchecker, C.; Sauvage, J.-P. Tetrahedron 1990, 46, 503.
9
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A R T I C L E S
Dietrich-Buchecker et al.
Figure 5. CSI-MS spectra of (a) 18a and (b) 20 (high resolution).
Scheme 5. Synthesis of [2]Catenane and Its Precursor via
Threading Pathway from Four Components
Figure 6. 1H NMR observation for the preparation of catenane 20 via
threading route (aromatic region, 500 MHz, 25 °C, 10 mM, TMS as an
external standard): (a) a mixture of ligand 1b and m-30 2 in CDCl3; (b)
Cu(I) complex 19 from 1b, 2, and Cu(CH3CN)4‚PF6 in DMF-d7; (c) [2]-
catenane 20 from 19 and enPd(NO3)2 in DMF-d7.
(Figure 5b). Addition of diethyl ether to the solution precipitated
Cu(I)Pd(II) catenane 20 as a brown powder in 85% yield.
Both Cu(I)-templating and Pd(II)-clipping steps proceed under
thermodynamic control. Therefore, catenane 20 is expected to
be generated quantitatively regardless of the order of the events.
Thus we also examined the one-step synthesis of 20 by mixing
all the required components at once. Namely, 1b, 2, Cu(CH3-
CN)4‚PF6, and enPd(NO3)2 were combined in 1:1:1:1 stoichi-
ometry in DMF at room temperature. Surprisingly, the one-
step synthesis was very efficient, and after 15 min, the NMR
of the resulting mixture clearly showed the quantitative forma-
tion of the same product (catenane 20) as a single product. This
result demonstrates that, under thermodynamic control, two
different metal centers (Cu(I) and Pd(II)) are selectively
coordinated by their most suitable coordination sites (phenan-
throline and pyridine, respectively). This very high site-
selectivity is ascribed to the remarkable stability of Cu(phen)2
type coordination, which allows the predominant coordination
of the phenanthroline sites on Cu(I) and subsequent interaction
of the Pd(II) center with pyridine residues.
spectrum of 19 in DMF-d7 showed 14 signals in the aromatic
region, five from ring 2, and nine from 1b (pyridine protons
are again missing). Chemical shift changes on complexation
are reasonable: downfield shifting of protons on the phenan-
throline core and upfield shifting of protons on phenylene Hm-1
and Ho-1 of 1b and Hm′ and Ho′ of 2. CSI-MS also confirmed
the structure of 19 with a parent ion peak at m/z 1451.9, which
is assigned as [19-PF6]+. From the solution, Cu(I) complex
19 was precipitated as a purple powder in 95% yield by adding
a large amount of diethyl ether.
Subsequently, [2]catenane 20 was quantitatively formed by
adding enPd(NO3)2 (1 mol equiv) to the DMF solution of 19.
Again, the NMR spectrum was in good agreement with the
structure of the desired [2]catenane 20 (Figure 6c). CSI-MS of
20 in a MeCN-DMF solvent also fully supported the structure
by a prominent peak at m/z 588.5 [(20-PF6-(NO3)2)+(dmf)2]3+
Conclusions
Two distinct strategies (templating and self-assembly) were
combined in designing and preparing a new type of coordination
catenane incorporating Cu(I) and Pd(II) metal centers. Two
approaches were examined and shown to be surprisingly
9
5722 J. AM. CHEM. SOC. VOL. 125, NO. 19, 2003

Quantitative Formation of [2]Catenanes
A R T I C L E S
overnight with 800 mg of wet KCN at room temperature. Progressive
disappearance of the initial red color could be observed. Once the
demetalation was complete, the pale yellow suspension was evaporated
to dryness and taken up in pure H2O, which afforded a yellow
precipitate. The latter was filtered on a filter paper and carefully washed
with water (discard KCN). The 498 mg of yellow solid, obtained upon
drying on a porous dish in air, was submitted to repetitive column
chromatographies (silica gel, CH2Cl2-1% MeOH as eluent) to afford
in 10% yield pure 1a as a pale yellow glass (49.5 mg, 0.05 mmol). 1H
NMR (200 MHz, CDCl3): δ 8.66 (d, 4H, Hm-4, J ) 6.2 Hz), 8.59 (d,
4H, Ho-1, J ) 8.6 Hz), 8.07 (s, 2H, H5,6), 8.03 (s, 2H, H3,8), 7.84 (d,
4H, Hm-1, J ) 8.4 Hz), 7.75 (d, 4H, Ho-2, J ) 8.6 Hz), 7.66 (d, 4H,
efficient: the entwining route (entwining of two ligands on the
Cu(I) template followed by Pd(II) clipping) and the threading
approach (Cu(I)-templated threading of a cyclic ligand on an
acyclic ligand followed by the Pd(II) clipping of the second
ring).
It is particularly interesting that the two powerful strategies,
templating and self-assembly, are complementary to each other.
While the templating method is quite predictable and convincing
for catenane synthesis, it requires two reaction steps (templating
followed by ring closure), and the yield in the latter step is not
always quantitative. On the other hand, the self-assembly method
is effective for the quantitative synthesis of catenanes in a single-
step reaction, but this method is not always predictable and
reliable. By combining these two strategies, we have established
a more powerful method for catenane synthesis. The formation
of the present Cu(I)/Pd(II) catenanes is highly predictable and
convincing thanks to the efficient Cu(I)-templating effect, while
it can be furnished in a single step in quantitative yields by
taking advantage of Pd(II)-directed self-assembly.
Hm-3, J ) 8.8 Hz), 7.52 (d, 4H, Ho-4, J ) 6.2 Hz), 7.19 (d, 4H, Hm-2,
J ) 8.6 Hz), 7.18 (d, 4H, Ho-3, J ) 8.8 Hz), 3.23 (t, 4H, Ha, J ) 7.6
Hz), 1.88 (m, 4H, Hb), 1.52 (m, 4H, Hc), 1.39 (m, 8H, Hd+e), 0.92 (m,
6H, Hf, J ) 6.8 Hz). MS (FAB): m/z 991.2 (MH+).
4-[4-(4-Bromophenoxy)phenyl]pyridine (7). 4-Bromophenyl ether
(5, 6.40 g, 19.5 mmol), 4-pyridylboronic acid pinacol ester (6, 2.00 g,
9.75 mmol), K3PO4 (2.49 g, 11.7 mmol), and [Pd(PPh3)4] (300 mg,
0.260 mmol) were mixed in 1,4-dioxane (150 mL) under argon, and
the mixture was refluxed at 100 °C. After 12 h, the product was
extracted with CHCl3 and purified by column chromatography (CHCl3-
MeOH, 20:1) to give 7 as a pale yellow powder (1.80 g, 56% yield).
Mp: 141-142 °C. 1H NMR (500 MHz, CDCl3): δ 8.67 (brs, 2H,
Experimental Section
General Procedures. All chemicals were of the best commercially
available grade and used without further purification. Ethylenediamine
was used for the cis-protection of Pd(II), as described earlier, to obtain
(en)Pd(NO3)2.28 Dry solvents were distilled from suitable desiccants
(Et2O from Na/benzophenone, dioxane from Na/benzophenone). TME-
DA was dried over NaH under argon for a night and filtered through
an alumina column. Column chromatography was performed with silica
gel 60 (Merck 9385, 230-400 mesh) or aluminum oxide 90 (neutral,
Hm-4), 7.62 (d, J ) 8.6 Hz, 2H, Hm-3), 7.49-7.46 (brs, 2H, Ho-4),
7.48 (d, J ) 8.8 Hz, 2H, Ho-2), 7.10 (d, J ) 8.6 Hz, 2H, Ho-3), 6.95
(d, J ) 8.8 Hz, 2H, Hm-2). 13C NMR (125 MHz, CDCl3): δ 158.0,
155.8, 150.3, 147.4, 133.3, 132.9, 128.5, 121.4, 121.0, 119.1, 116.4.
Anal. Calcd for C17H12OBrN: C, 62.60; H, 3.71; N, 4.29. Found: C,
62.67; H, 3.83; N, 4.18. IR (KBr, cm-1): 1608, 1596, 1579, 1511,
1477, 1234, 1169, 1010, 844, 808, 591, 556. MS (EI): m/z 325.0 (M+).
1
act. II-III, Merck 1097). H and 13C NMR spectra for ligands were
4-[4-(4-Trimethylstannylphenoxy)phenyl]pyridine (8). THF solu-
tion (20 mL) of 7 (1.00 g, 3.07 mmol) was added dropwise to a THF
(40 mL) solution of n-BuLi (2.4 mL, 1.55 M in hexane, 3.70 mmol) at
-80 °C under argon, and the mixture was stirred for 1 h. Me3SnCl
(3.7 mL, 1.0 M in THF, 3.70 mmol) was added to the solution at the
same temperature. After being stirred for 1 h, the mixture was warmed
to room temperature and stirred for 5 h. The product was extracted
with CHCl3 and purified by column chromatography (CHCl3-MeOH,
20:1) to give 8 as a white powder (1.05 g, yield 84%). Mp: 85-86
recorded on either a Bruker WP 200 SY (200 MHz) or a AC 300 (300
MHz) spectrometer with deuterated solvent as the lock and residual
solvent as the internal reference. 1H NMR spectra for complexes 17-
20 and part of the ligand were recorded on a Bruker DRX 500
spectrometer: these data were collected at ambient temperature unless
otherwise noted, and the chemical shift values reported here are with
respect to external TMS standard; 13C NMR, H-H COSY, H-H
NOESY, and C-H COSY spectra were recorded on a Bruker AMX
500 spectrometer. Deuterated solvents were acquired from Cambridge
Isotopic Laboratories, Inc., and used as such for the complexation
reactions and NMR measurements. Infrared spectra were recorded on
a Shimadzu FTIR-8300 spectrometer with samples in compressed KBr
disks. Mass spectra were obtained on a ZAB-HF spectrometer (FAB)
and on a Waters Integrity TM system coupled with a Thermabeam
TM mass detector (EI). CSI-MS data were measured on a four-sector
(BE/BE) tandem mass spectrometer (JMS-700T, JEOL) equipped with
a CSI source. Melting points were determined on a Yanaco MP-500.
4,7-Di-n-hexyl-2,9-bis[4′-(4-pyridyl-4-phenoxy)biphenyl]-1,10-
phenanthroline (1a). 4,7-Di-n-hexyl-2,9-bis[4-(4-hydroxyphenyl)-
phenyl]-1,10-phenanthroline (3, 416 mg, 0.6 mmol), 4-(4-bromophenyl)-
pyridine (4, 234 mg, 1.0 mmol), Cu(CH3CN)4‚PF6 (113 mg, 0.3 mmol),
Cs2O3 (652 mg, 0.5 mmol), and 450 mg of crushed activated 4 Å
molecular sieves were poured, under argon and in the solid state, into
a 50 mL three-necked round-bottomed flask. These solids were
subsequently covered with 3 mL of anhydrous toluene. The resulting
suspension was refluxed (110 °C) under argon during 72 h (5 mL of
toluene and 2 mL of dimethylformamide were added after 24 h to the
mixture in order to allow reasonable stirring). Thereafter solvents were
evaporated to dryness, and the almost black gummy residue was taken
up in a mixture of CH2Cl2, MeCN, and MeOH and submitted to an
anion exchange with a saturated KPF6-H2O solution. After decantation
of the water layer, the remaining dark red organic phase was stirred
1
°C. H NMR (500 MHz, CDCl3): δ 8.63 (d, J ) 6.0 Hz, 2H, Hm-4),
7.60 (d, J ) 8.6 Hz, 2H, Hm-3), 7.49 (d, J ) 8.4 Hz, 2H, Ho-2), 7.46
(d, J ) 6.0 Hz, 2H, Ho-4), 7.10 (d, J ) 8.6 Hz, 2H, Ho-3), 7.06 (d, J
) 8.4 Hz, 2H, Hm-2), 0.30 (s, 9H, -CH3). 13C NMR (125 MHz,
CDCl3): δ 158.4, 156.8, 150.2,147.5, 137.0, 136.8, 132.7, 128.3, 121.2,
118.9, 118.6, -9.5. IR (KBr, cm-1): 1608, 1576, 1485, 1251, 1224,
1169, 807, 802, 769, 712, 530. Anal. Calcd for C20H21NOSn: C, 58.57;
H, 5.16; N, 3.42. Found: C, 58.35; H, 5.10; N 3.29. MS (EI): m/z 396
(M+ - CH3).
Preparation of 2-(p-Bromophenyl)-1,10-phenanthroline (9). A 62
mL portion (100 mmol) of a 1.6 M n-butyllithium solution in hexane
was rapidly added to a degassed solution of p-dibromobenzene (26.0
g, 110 mmol) in anhydrous diethyl ether (150 mL) at room temperature
and titrated. Then 210 mL (63 mmol) of the 0.3 M p-bromophenyl-
lithium solution thus obtained was slowly added, by the means of a
double-ended needle, to a degassed suspension of 1,10-phenanthroline
monohydrate (4.95 g, 25 mmol) in 180 mL of anhydrous Et2O kept at
0 °C. After the resulting dark red solution was stirred for 2 h 30 min
under argon at 2 °C, it was hydrolyzed with water at 0 °C. The bright
yellow Et2O layer was decanted and the aqueous layer extracted three
times with 200 mL portions of CH2Cl2. The combined organic layers
were thereafter rearomatized by successive additions of MnO2 under
effective magnetic stirring (MnO2 Merck No. 805958). This reoxidation,
easily followed by TLC and the disappearance of the yellow color,
was ended after the addition of 73 g of MnO2. After the mixture was
dried over MgSO4, the black slurry could be easily filtered on a sintered
(28) Fujita, M.; Yazaki, J.; Ogura, K. J. Am. Chem. Soc. 1990, 112, 5645.
9
J. AM. CHEM. SOC. VOL. 125, NO. 19, 2003 5723

A R T I C L E S
Dietrich-Buchecker et al.
glass and the filtrate evaporated to dryness to give 14.9 g of crude 9,
which crystallized upon cooling. This crude solid was filtered over a
sintered glass and washed with cold C6H6 and subsequently with cold
Et2O, affording 5.93 g (17.7 mmol) of pure 9. An additional 1.0 g (2.98
mmol) of 9 could be obtained by column chromatography on silica
gel (eluent: CH2Cl2, 1% MeOH). Overall yield: 82% (6.93 g, 20.68
mmol), colorless solid (mp 187-189 °C). 1H NMR (200 MHz,
CDCl3): 9.23 (dd, 1H, H9, J1 ) 4.4 Hz, J2 ) 1.8 Hz), 8.29 (d, 1H, H4,
J ) 8.4 Hz), 8.25 (dd, 1H, H7, J1 ) 8.4 Hz, J2 ) 1.8 Hz), 8.22 (d, 1H,
was stirred overnight and then allowed to warm to room temperature
before hydrolysis with 100 mL of a 4 M HCl solution. The two layers
were separated, and ether was evaporated. The solid was taken up in
100 mL of aqueous Na2CO3 (2 M) and 100 mL of Et2O. The two layers
were separated again. The aqueous layer was acidified and extracted
three times with 100 mL of Et2O. The combined organic layers were
dried over MgSO4 to yield the free acid boronic derivative as a white
solid (0.86 g). This solid was dissolved in 30 mL of benzene with 0.31
g of 2,2-dimethyl-1,3-propanediol (1 equiv) and a catalytic amount of
p-toluenesulfonic acid. This mixture was heated under reflux for 2 h.
Evaporation of the solvent gave 13 as a white solid (1.06 g, 70% yield).
1H NMR (200 MHz, CDCl3): δ 7.78 (d, J ) 8.4 Hz, 2H), 7.44 (d, J
) 9.1 Hz, 2H), 6.96 (d, J ) 9.1 Hz, 2H), 6.91 (d, J ) 8.4 Hz, 2H),
3.77 (s, 4H), 1.03 (s, 6H). 13C NMR (200 MHz, CDCl3): δ 156.1,
153.0, 135.7, 132.7, 129.7, 120.8, 117.8, 116.0, 72.3, 31.9, 21.9. Anal.
Calcd for C17H18O3BBr: C, 56.55; H, 5.03. Found: C, 56.50; H, 4.93.
MS (EI): m/z 360.1 (M+).
H0-1, J ) 8.2 Hz), 8.04 (d, 1H, H3, J ) 8.4 Hz), 7.78 (AB, 2H, H5,6,
J ) 10.2 Hz), 7.66 (d, 2H, Hm-1, J ) 8.8 Hz). Anal. Calc for C18H11N2-
Br: C, 64.50; H, 3.31; N, 8.36. Found: C, 64.75; H, 3.20; N, 8.66. MS
(EI): m/z found 335, calc 335.2.
Preparation of 2,9-Bis(p-bromophenyl)-1,10-phenanthroline (10).
A 25 mL sample of an etheral solution of p-bromophenyllithium
(prepared as above from 2.9 g, 12 mmol of p-dibromobenzenze, and
11 mmol of n-Buli) was slowly added, by means of a double-ended
needle, to a degassed suspension of 9 (2.01 g, 6 mmol) in 70 mL of
anhydrous Et2O maintained at 2 °C. The resulting dark purple solution
was stirred during three further hours at 3 °C. After hydrolysis at 0
°C, decantation, three extractions with CH2Cl2, and rearomatization with
8.0 g of MnO2, 3.05 g of a crude mixture was obtained as a pale yellow
solid. Column chromatography of the latter over silica gel (eluent: CH2-
Cl2, 0.5% MeOH) afforded pure 10 (2.6 g, 5.30 mmol, 88% yield) as
a colorless solid (mp 219-221°C). 1H NMR (200 MHz, CDCl3): 8.33
(d, 4H, Ho-1, J ) 8.8 Hz), 8.33 (d, 2H, H4,7, J ) 8.8 Hz), 8.12 (d, 2H,
Compound 7. To a degassed solution of 4-bromopyridine hydro-
chloride (14, 0.65 g, 3.36 mmol) and [Pd(PPh3)4] (110 mg, 0.17 mmol)
in 80 mL of toluene were added 30 mL of a degassed solution of 2 M
aqueous Na2CO3 and a solution of 13 (1.21 g, 3.36 mmol) in 20 mL of
toluene under argon. It is very important to respect the following
sequence in the additions: (1) 4-iodopyridine in toluene, (2) vacuum/
Ar three times, (3) addition of the catalyst, (4) vacuum/Ar three times,
(5) addition of the degassed solution of Na2CO3, (6) addition of the
degassed solution of the boronic ester. After 2 h of reflux, the reaction
mixture was allowed to cool to room temperature. The solvent was
evaporated, and the crude product was chromatographed over alumina
using hexane-dichloromethane as the eluents. Compound 7 was
obtained (CH2Cl2) as a white solid (0.92 g, 80% yield).
H3,8, J ) 8.4 Hz), 7.81 (s, 2H, H5,6), 7.73 (d, 4H, Hm-1, J ) 8.8 Hz).
Anal. Calc for C24H14N2Br2: C, 58.81; H, 2.88; N, 5.71. Found: C,
59.04; H, 2.79; N, 5.74. MS (EI): m/z found 490, calc 490.2.
2,9-Bis[4′-(4-pyridyl-4-phenoxy)biphenyl]-1,10-phenanthroline (1b).
Compound 8 (400 mg, 0.98 mmol), LiCl (170 mg, 4.00 mmol), and
[PdCl2(PPh3)2] (30 mg, 0.04 mmol) were combined in toluene (50 mL)
under argon. 2,9-Bis(4-bromophenyl)-1,10-phenanthroline (10, 196 mg,
0.40 mmol) in toluene (30 mL) was added to the mixture, and the
mixture was stirred at 120 °C. After 12 h, the product was extracted
with CHCl3 and purified by column chromatography (CHCl3-MeOH,
20:1) to give 1b as colorless crystals (150 mg, yield 45%). Mp: 249-
4-Boronic Ester-4′-pyridyldiphenyl Ether (16). Bis-pinacolato
diboron (15, 0.63 g, 2.48 mmol), 7 (0.74 g, 2.26 mmol), KOAc (0.67
g, 6.78 mmol), and Pd(dppf)Cl2‚CH2Cl2 (55 mg, 0.07 mmol) were
dissolved in freshly distilled dioxane (15 mL). The mixture was stirred
under argon at 80 °C for 14 h. After the solution had cooled to room
temperature, 20 mL of water was added. The dioxane was evaporated
under vacuum, and 100 mL of CH2Cl2 was added. The organic layer
was dried over MgSO4, filtered, and evaporated. The crude was then
purified on a short silica column to give a black oil (yield 95%). The
1H NMR was very nice, and the product was used without other
purification. 1H NMR (200 MHz, CDCl3): δ 8.65 (d, J ) 6.2 Hz, 2H),
7.83 (d, J ) 8,6 Hz, 2H), 7.62 (d, J ) 8.6 Hz, 2H), 7,49 (d, J ) 6.2
Hz, 2H), 7.12 (d, J ) 8.6 Hz, 2H), 7.05 (d, J ) 8.6 Hz, 2H), 1.36 (s,
12H).
1
250 °C. H NMR (500 MHz, CDCl3): δ 8.66 (d, J ) 6.1 Hz, 4H,
Hm-4), 8.59 (d, J ) 8.3 Hz, 4H, Ho-1), 8.35 (d, J ) 8.3 Hz, 2H, H4,7),
8.22 (d, J ) 8.3 Hz, 2H, H3,8), 7.84 (d, J ) 8.3 Hz, 4H, Hm-1), 7.83 (s,
2H, H5,6), 7.75 (d, J ) 8.4 Hz, 4H, Ho-2), 7.65 (d, J ) 8.7 Hz, 4H,
Hm-3), 7.50 (d, J ) 6.1 Hz, 4H, Ho-4), 7.19 (d, J ) 8.7 Hz, 4H, Ho-3),
7.18 (d, J ) 8.4 Hz, 4H, Hm-2). 13C NMR (125 MHz, CDCl3): δ 156.3,
154.2, 153.9, 147.3, 146.0, 143.7, 139.0, 135.9, 134.9, 134.1, 130.2,
126.3, 126.2, 125.9, 125.8, 125.0, 123.8, 119.3, 118.0, 117.5, 116.8.
IR (KBr, cm-1): 1596, 1506, 1484, 1245, 835, 818, 798, 418. Anal.
Calcd for C58H38O2N4‚H2O: C, 82.84; H, 4.74; N, 6.66. Found: C,
82.86; H, 4.68; N, 6.57.
Ligand 1b. To a degassed solution of 2,9-bis(4-bromophenyl)-
1,10-phenanthroline 10 (0.45 g, 0.91 mmol) and [Pd(PPh3)4] (84 mg,
0.07 mmol) in 30 mL of toluene were added 9 mL of a degassed
solution of 2 M aqueous Na2CO3 and a solution of 16 (0.75 g, 2.00
mmol) in 10 mL of toluene under argon. After 17 h of reflux, the
reaction mixture was allowed to cool to room temperature and a
precipitate appeared. It was filtered off and washed with water, toluene,
and ether to yield 0.60 g of the ligand 1b (yield 80%).
4-Bromo-4′-iododiphenyl Ether (12). 4-Bromodiphenyl ether (11,
5 g, 20 mmol) was stirred in 100 mL of acetic acid. ICl (4.9 g, 30
mmol) in 30 mL of acetic acid was added dropwise to the solution at
room temperature. When the addition was over, the solution was heated
at reflux for 2 h. The acetic acid was then evaporated. The solid was
taken up in CH2Cl2. The solution was decolorized with 10% Na2S2O3,
and Na2CO3 was added until pH ) 7. The organic layer was also washed
with water. After extracting with CH2Cl2, drying over MgSO4,
evaporating the solvent, and recrystallizing in hexane, the product was
obtained as a white solid (7.3 g, yield 99%). 1H NMR (200 MHz,
CDCl3): δ 7.63 (d, J ) 9.0 Hz, 2H), 7.45 (d, J ) 8.8 Hz, 2H), 6.88 (d,
J ) 9.0 Hz, 2H), 6.88 (d, J ) 8.8 Hz, 2H).
4-Bromo-4′-diphenyl Ether Boronic Ester (13). A solution of 1.58
g of 12 (4.22 mmol) in 70 mL of diethyl ether was degassed and cooled
to -78 °C. Then, 0.63 mL of TMEDA (4.22 mmol) were added,
followed by 2.7 mL of n-butyllithium in hexane (4.64 mmol). After
stirring for 3 h at -78 °C, a degassed solution of trimethylborate (1.68
g, 17 mmol) in 15 mL of dry Et2O was added via cannula. The reaction
[Cu(1b)2]‚PF6 (17b). Ligand 1b (33.0 mg, 0.04 mmol) and Cu(CH3-
CN)4‚PF6 (7.5 mg, 0.02 mmol) were combined in DMF (1 mL) at room
temperature under argon. The mixture was stirred for 15 min to give
a clear dark red solution. Cu(I) complex 17b was precipitated as a purple
powder by adding a large amount of diethyl ether. Yield: 93%. Mp:
1
191-192 °C dec. H NMR (500 MHz, DMF-d7): δ 9.27 (d, J ) 8.4
Hz, 4H, H4,7), 8.66 (d, J ) 8.4 Hz, 4H, H3,8), 8.62 (s, 4H, H5,6), 8.48
(d, J ) 8.0 Hz, 8H, Hm-3), 8.26 (d, J ) 7.7 Hz, 8H, Ho-1), 7.86 (d, J
) 8.2 Hz, 8H, Ho-2), 7.73 (d, J ) 8.0 Hz, 8H, Ho-3), 7.69 (d, J ) 8.2
Hz, 8H, Hm-2), 7.46 (d, J ) 7.7 Hz, 8H, Hm-1). 13C NMR (125 MHz,
DMF-d7): δ 158.7 (Cq), 157.1 (Cq), 156.7 (Cq), 144.1 (Cq), 140.9
(Cq), 138.44 (CH4,7), 138.39 (Cq), 135.7 (Cq), 129.4 (CHo-1), 129.2
(CHo-2), 129.1 (CHm-3), 127.2 (CH5,6), 126.0 (CHm-1), 125.3 (CH3,8),
9
5724 J. AM. CHEM. SOC. VOL. 125, NO. 19, 2003

Quantitative Formation of [2]Catenanes
A R T I C L E S
120.0 (CHo-3), 119.9 (CHm-2). IR (KBr, cm-1): 1597, 1485, 1244,
1174, 842, 557. CSI-MS m/z 1708.04 [17b - PF6]+.
[Cu(1b)(2)]‚PF6 (19). Ligand 1b (33.0 mg, 0.04 mmol), m-30 228
(22.6 mg, 0.04 mmol), and CuPF6‚4CH3CN (15.0 mg, 0.04 mmol) were
combined in DMF (2 mL) at room temperature under argon. The
mixture was stirred for 15 min to give a clear dark red solution. Cu
complex 19 was isolated as a purple powder by adding a large amount
[Cu(enPd)2(1b)2]‚PF6‚(NO3)4 (18b). Cu(I) complex 17b (18.5 mg,
0.01 mmol) and (en)Pd(NO3)2 (5.8 mg, 0.02 mmol) were combined in
DMF (1 mL) at room temperature, and the mixture was stirred for 30
min. The solution color was slightly changed to reddish brown from
dark red. Cu(I)Pd(II) complex 18b was precipitated as a reddish purple
powder by adding a large amount of diethyl ether, and it was
recrystallized from DMF-MeOH-diethyl ether as deep red microc-
rystals. Yield: 92%. Mp > 300 °C. 1H NMR (500 MHz, DMF-d7): δ
9.64 (d, J ) 6.3 Hz, 8H, Hm-4), 9.14 (d, J ) 8.3 Hz, 4H, H4,7), 8.73 (d,
J ) 6.3 Hz, 8H, Ho-4), 8.70 (d, J ) 8.6 Hz, 2H, Hm-3), 8.61 (d, J )
8.3 Hz, 4H, H3,8), 8.49 (s, 4H, H5,6), 8.25 (d, J ) 8.0 Hz, 8H, Ho-1),
7.89 (d, J ) 8.6 Hz, 8H, Ho-3), 7.60-7.55 (d, 16H, Hm-2 and Ho-2),
7.32 (d, J ) 8.0 Hz, 8H, Hm-1), 3.57 (brs, 8H, H-en). 13C NMR (125
MHz, DMF-d7): δ 159.5 (Cq), 158.3 (Cq), 156.4 (Cq), 152.9 (CHa),
150.7 (Cq), 143.9 (Cq), 140.9 (Cq), 138.4 (Cq), 138.3 (CH4,7), 135.0
(Cq), 131.4 (Cq), 130.2 (CHm-3), 129.6 (CHo-1), 129.1 (Cq), 128.9
(CHm-2 or CHo-2), 127.1 (CH5,6), 125.6 (CHm-1), 124.7 (CH3,8), 123.8
(CHb), 121.8 (CHo-3), 118.7 (CHm-2 or CHo-2), 48.0 (CH2). IR (KBr,
cm-1): 1596, 1486, 1385, 1246, 1174, 841, 557. CSI-MS: m/z 546.5
1
of diethyl ether. Yield: 95%. Mp: 163-164 °C dec. H NMR (500
MHz, DMF-d7): δ 9.43 (d, J ) 8.3 Hz, 2H, H4,7), 9.19 (d, J ) 8.3 Hz,
2H, H4′,7′), 8.96 (s, 2H, H5,6), 8.73 (d, J ) 8.3 Hz, 2H, H3,8), 8.59 (s,
2H, H5′,6′), 8.53 (d, J ) 8.3 Hz, 2H, H3′,8′), 8.47 (d, J ) 7.9 Hz, 4H,
Hm-3), 8.29 (d, J ) 8.0 Hz, 4H, Ho-1), 7.99 (d, J ) 8.4 Hz, 4H, Ho′),
7.88 (d, J ) 8.4 Hz, 4H, Ho-2), 7.74 (d, J ) 7.9 Hz, 4H, Ho-3), 7.69
(d, J ) 8.4 Hz, 4H, Hm-2), 7.45 (d, J ) 8.0 Hz, 4H, Hm-1), 6.67 (d, J
) 8.4 Hz, 4H, Hm′), 4.38-4.15 (brs, 20H, CH2). 13C NMR (125 MHz,
DMF-d7): δ 159.6 (Cq), 158.7 (Cq), 157.10 (Cq), 157.05 (Cq), 156.2
(Cq), 143.9 (Cq), 140.8 (Cq), 138.9 (CH4,7), 138.4 (Cq), 137.9 (CH4′,7′),
135.7 (Cq), 132.9 (Cq), 130.1 (CHo′), 129.4 (CHo-1), 129.14 (CHm-3),
129.06 (CHo-2), 128.7 (Cq), 128.1 (CH5,6), 126.8 (CH5′,6′), 125.8
(CHm-1), 125.1 (CH3,8), 124.6 (CH3′,8′), 120.0 (CHm-2), 119.9 (CHo-3),
113.6 (CHm′), 71.5, 71.0, 69.1, 67.4, 65.8 15.4 (CH2). IR (KBr, cm-1):
1596, 1486, 1245, 1175, 1108, 841,557. CSI-MS m/z 1451.86 [19 -
PF6]+.
[(18b - PF6 - (NO3)3) + (MeCN)2]4+, 721.6 [(18b - PF6
-
(NO3)2)]3+
.
[Cu(enPd)(1b)(2)]‚PF6‚(NO3)2 (20). This complex was obtained as
a brown powder by the reaction of (en)Pd(NO3)2 (2.9 mg, 0.01 mmol)
with 19 (16.6 mg, 0.01 mmol) in DMF (1 mL) in a manner similar to
that of 18b. Yield: 85%. Mp: 262-263 °C dec. 1H NMR (500 MHz,
DMF-d7): δ 9.61 (d, J ) 6.6 Hz, 4H, Hm-4), 9.43 (d, J ) 8.3 Hz, 2H,
[Cu(1a)2]‚PF6 (17a) and [Cu(enPd)2(1a)2]‚PF6‚(NO3)4 (18a). Ligand
1a (9.9 mg, 0.010 mmol) and Cu(CH3CN)4‚PF6 (1.9 mg, 0.005 mmol)
were combined in CH3CN-DMF (1:1, 1 mL) at room temperature.
The mixture was stirred for 15 min to give a clear dark red solution.
In a control experiment using CD3CN-DMF-d7 (1:1), the exclusive
formation of 16a was confirmed by NMR. To the dark red solution of
17a was added (en)Pd(NO3)2 (2.9 mg, 0.010 mmol), and the reaction
mixture was stirred for 1 h at room temperature. From the red reaction
solution, 18a was isolated as red microcrystals by adding a large amount
of diethyl ether (12.5 mg, 85%). Physical properties of 17a: 1H NMR
(500 MHz, CD3CN-DMF-d7): δ 8.91 (s, 4H, H5,6), 8.53 (d, J ) 8.8
Hz, 8H, Ho-2), 8.52 (s, 4H, H3,8), 8.36 (d, J ) 8.3 Hz, 8H, Hm-1), 7.87
(d, J ) 8.5 Hz, 8H, Hm-3), 7.86 (d, J ) 8.8 Hz, 8H, Hm-2), 7.80 (d, J
) 8.5 Hz, 8H, Ho-3), 7.50 (d, J ) 8.3 Hz, 8H, Ho-1), 3.79 and 2.33-
1.93 (m, 40H, -CH2-), 1.53 (t, J ) 6.5 and 7.0 Hz, 12H, -CH3).
CSI-MS data for 17a were obtained by analyzing the CH3CN-DMF
(1:1) solution of 17a (5 mM), which was prepared independently: m/z
2046.2, [17a - PF6]+. Physical properties of 18a: 1H NMR (500 MHz,
CD3CN-DMF-d7): δ 9.67 (d, J ) 6.8 Hz, 8H, Hm-4), 8.72 (d, J )
8.8 Hz, 8H, Ho-2), 8.70 (s, 4H, H5,6), 8.69 (d, J ) 6.8 Hz, 8H, Ho-3),
8.48 (s, 4H, H3,8), 8.32 (d, J ) 8.0 Hz, 8H, Hm-1), 7.97 (d, J ) 8.8 Hz,
8H, Hm-2), 7.40 (d, J ) 8.0 Hz, 8H, Ho-1), 6.49 (brs, 8H), 3.64 and
2.24-1.83 (m, 40H, -CH2-), 1.46 (t, J ) 6.5 and 7.5 Hz, 12H, -CH3).
CSI-MS data for 18a was obtained by analyzing the CH3CN-DMF
(1:1) solution of 18a (0.25 mM), which was prepared independently:
m/z 548.8 [(18a - PF6 - (NO3)4) + (dmf)5]5+, 646.7 [(18a - PF6 -
(NO3)3) + (dmf)2]4+, 834.5 [18a - PF6 - (NO3)2]3+. CSI-HRMS:
calcd for [(18a - PF6 - (NO3)4) + (dmf)5]5+ m/z 548.8238; found
548.8193.
H4,7), 9.02 (d, J ) 8.3 Hz, 2H, H4′,7′), 8.97 (s, 2H, H5,6), 8.74 (d, J )
8.3 Hz, 2H, H3,8), 8.70 (d, J ) 6.6 Hz, 4H, Ho-4), 8.67 (d, J ) 8.7 Hz,
4H, Hm-3), 8.43 (d, J ) 8.3 Hz, 2H, H3′,8′), 8.38 (s, 2H, H5′,6′), 8.28 (d,
J ) 8.1 Hz, 4H, Ho-1), 7.98 (d, J ) 8.5 Hz, 4H, Ho′), 7.86 (d, J ) 8.7
Hz, 4H, Ho-3), 7.62 (d, J ) 8.6 Hz, 4H, Ho-2), 7.54 (d, J ) 8.6 Hz,
4H, Hm-2), 7.31 (d, J ) 8.1 Hz, 4H, Hm-1), 6.62 (d, J ) 8.5 Hz, 4H,
Hm′), 4.36-4.13 (brs, 20H, CH2), 3.56 (brs, 4H, en). 13C NMR (125
MHz, DMF-d7): δ 159.7 (Cq), 159.5 (Cq), 158.2 (Cq), 156.9 (Cq),
155.9 (Cq), 152.9 (CHa), 150.7 (Cq), 143.8 (Cq), 143.7 (Cq), 140.6
(Cq), 138.8 (CH4,7), 138.6 (Cq), 137.8 (CH4′,7′), 135.1 (Cq), 132.5 (Cq),
131.3 (Cq), 130.3 (CHo′), 130.2 (CHm-3), 129.5 (CHo-1), 129.3 (Cq),
128.9 (CHo-2), 128.5 (Cq), 128.1 (CH5,6), 126.6 (CH5′,6′), 125.5 (CHm-1),
124.5 (CH3,8), 124.4 (CH3′,8′), 123.8 (CHb), 121.7 (CHo-3), 118.8
(CHm-2), 113.4 (CHm′), 71.5, 71.0, 70.9, 69.0, 67.3, 65.8, 48.0 (CH2).
IR (KBr, cm-1): 1596, 1487, 1384, 1247, 1176, 842, 557. CSI-
HRMS: calcd for [(20 - PF6 - (NO3)2) + (dmf)2]3+ m/z 588.5172;
found 588.5159.
Acknowledgment. We acknowledge the French Ministry of
National Education for a fellowship (for B.C.).
JA021370L
9
J. AM. CHEM. SOC. VOL. 125, NO. 19, 2003 5725