Hydrindacene-based acetylenic macrocycles with horizontally and vertically ordered functionality arrays

Article abstract of DOI:10.1002/chem.201200716

The macrocyclization of 2,6-diethynyl hydrindacenes (1) with functional groups at mutually perpendicular positions results in the formation of novel macrocycles which, as a result of the hindered rotation of the hydrindacene units, possess directionally persistent peripheral functionalities. The two hydrindacene units in the dimer macrocycle (2) have been shown to interact electronically through their respective butadiyne moieties, whereas the trimer macrocycle (3) demonstrates a moderate degree of geometrical flexibility as a result of the five-membered hydrindacene rings. In addition, these trimer macrocycles contain a central cavity suitably sized for the inclusion of various solvent molecules. These new macrocycles can be further modified by introducing π-conjugated side groups, such as styryl and thienyl groups, as well as by attaching a variety of peripheral ester groups. Copyright

Full text of DOI:10.1002/chem.201200716

FULL PAPER
DOI: 10.1002/chem.201200716
Hydrindacene-Based Acetylenic Macrocycles with Horizontally and
Vertically Ordered Functionality Arrays
Hidetoshi Kawai,*[a, b] Tatsuya Utamura,[b] Erina Motoi,[b] Tomoko Takahashi,[b]
Hiroyoshi Sugino,[b] Manabu Tamura,[b] Masakazu Ohkita,[c] Kenshu Fujiwara,[b]
Takao Saito,[a] Takashi Tsuji,[b] and Takanori Suzuki[b]
Abstract: The macrocyclization of 2,6-
diethynyl hydrindacenes (1) with func-
tional groups at mutually perpendicular
positions results in the formation of
novel macrocycles which, as a result of
the hindered rotation of the hydrinda-
cene units, possess directionally persis-
tent peripheral functionalities. The two
hydrindacene units in the dimer macro-
cycle (2) have been shown to interact
electronically through their respective
butadiyne moieties, whereas the trimer
macrocycle (3) demonstrates a moder-
ate degree of geometrical flexibility as
a result of the five-membered hydrin-
dacene rings. In addition, these trimer
macrocycles contain a central cavity
suitably sized for the inclusion of vari-
ous solvent molecules. These new mac-
rocycles can be further modified by in-
troducing p-conjugated side groups,
such as styryl and thienyl groups, as
well as by attaching a variety of periph-
eral ester groups.
Keywords: alkynes · inclusion com-
pounds · macrocycles · solid-state
structures · through-bond interac-
tions
Introduction
Macrocycles[1] that feature pre-
organized cavities and well-de-
fined structures that are ame-
nable to modification have at-
tracted significant interest to
date on account of their novel
properties and potential appli-
cations.[2] Arylene and ethynylene units have often been
used to form such shape-persistent macrocycles.[3–10] One ex-
ample of a noteworthy property of some planar shape-per-
sistent macrocycles, such as m-phenyleneethynylene macro-
cycles[4] and dehydrobenzo[n]annulenes,[5] is the formation
of an internal void upon self-assembly based on p–p stack-
ing. In addition, belt-shaped macrocycles[7–15] that consist of
rotatable phenylene units—including p-phenyleneethynylene
macrocycles (CPPAs[7,8] and their homologues[9]), cycloary-
lenes,[10] calixarenes,[11] and pillararenes[12]—all feature inter-
nal voids and thus might form molecular complexes with a
variety of guest species. Further unique and interesting
properties might be obtained by modifying the cyclic back-
bones of such macrocycles by attaching various peripheral
functional groups oriented both horizontally and vertically
relative to the plane defined by the macrocycle. However,
additional structural modifications are also necessary to sup-
press rotation of the phenylene scaffolds, and thus to obtain
a well-defined and persistent array of peripheral functional
groups. Fixation of the rotational units within some macro-
cycles can be achieved by increasing their rotational energy
barrier through attaching alkyl chains onto the phenylene
units, or by the addition of covalently bound groups to form
cyclic ladder-shaped structures,[13] as in the case with cavi-
tands[14] and cucurbiturils.[2e] This approach to rotational fix-
ation of the macrocycle, however, limits the options for any
additional modifications of the molecules. An alternative ap-
proach to suppressing rotation is to connect the quaternary
or tertiary carbon atoms on the individual ring units, as is
the case in cyclodextrins and their analogues.[15]
[a] Prof. H. Kawai, T. Saito
Department of Chemistry, Faculty of Science
Tokyo University of Science
1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601 (Japan)
Fax : (+81)3-5228-8255
E-mail: kawaih@rs.tus.ac.jp
[b] Prof. H. Kawai, T. Utamura, E. Motoi, T. Takahashi, H. Sugino,
M. Tamura, Prof. K. Fujiwara, Prof. T. Tsuji, Prof. T. Suzuki
Department of Chemistry, Faculty of Science
Hokkaido University
Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan)
[c] Prof. M. Ohkita
Department of Material Science and Engineering
Graduate School of Engineering
Nagoya Institute of Technology
Gokiso-cho, Showa-ku, Nagoya, 466-8555 (Japan)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201200716.
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In this article, we report the design and synthesis of a
series of novel macrocycles (2–4), all of which are function-
alized in both the horizontal and vertical directions relative
to the plane defined by the macrocyclic backbone
(Scheme 1). These structures were prepared through Eglin-
ble monomer unit for the construction of macrocycles with
directional-persistent peripheral functionalities. Macrocycli-
zation was anticipated to proceed through the coupling of
the ethynyl groups at the C2 and C6 quaternary carbon
atoms of the hydrindacene units, thereby producing novel
macrocycles with horizontally and vertically ordered func-
tionality arrays, whereby rotation of the macrocycle units is
effectively suppressed. At the same time, the five-membered
rings of the hydrindacene units, each of which is puckered
into an envelope conformation, confer a moderate degree of
geometrical flexibility to the macrocycle as a result of ring
flipping. In spite of the inherent flexibility of the five-mem-
bered ring on the basis of ring flipping, however, the struc-
tural stability that results from the formation of macrocyclic
dimers and trimers is enough to maintain the planarity of
the macrocycle, and therefore the mutually perpendicular
directionality between the functional groups X and Z will be
maintained.
Preparation of 4,8-disubstituted hydrindacene derivatives: A
series of 2,2,6,6-hydrindacene tetraesters with vertical sub-
stituents at the 4,8-positions (9a–d) were prepared from the
1,4-disubstituted
2,3,5,6-tetrakis(bromomethyl)benzenes
8a,b[19,20] (Scheme 2). Although several synthetic procedures
for the preparation of methoxy derivative 8a have been re-
ported,[19] all required expensive starting materials such as
duroquinone[19a] or 2,3-dimethylhydroquinone.[19b] For this
reason, we developed a new synthetic route for 8a as depict-
ed in Scheme 2. Methylation of the relatively inexpensive
starting compound 2,3,5-trimethylhydroquinone 5 with CH3I
gave methyl ether 6,[21] and subsequent bromomethylation[22]
of 6 with paraformaldehyde/HBr in AcOH produced mono-
bromide 7.[23] Treatment of 7 with NBS in CH2Cl2 under
Scheme 1. Construction of hydrindacene-based macrocycles 2–4.
ton coupling reactions of the 2,6-diethynylhydrindacenes
1a–d. The details of the synthetic procedures are presented
herein, in addition to the results of X-ray structural analysis
and the optical and redox properties of the resulting macro-
cycles.
Results and Discussion
Molecular design of hydrindacene-based macrocycles: This
novel class of macrocycles, which consists of 2–4, utilizes hy-
drindacene (1,2,3,5,6,7-hexahydro-s-indacene (1)) as the
basic monomer unit. As shown in Scheme 1, the hydrinda-
cene monomer is composed of a rigid aromatic ring with a
five-membered alicyclic ring on either side. We recently re-
ported that hydrindacene might be used as a versatile scaf-
fold[16–18] for the synthesis of various supramolecular assem-
blies, including a rotaxane template[16] and allosteric[17] or
functionality-selective receptors.[18] These varied assemblies
result from the multidimensional modification of hydrinda-
cene based on the addition of substituents X, Y, and Z
(Scheme 1). Substituents X and Y, at the 2,6-positions on
the five-membered rings, and substituent Z, at the 4,8-posi-
tions on the aromatic ring, are all mutually perpendicular to
one another. The two Y substituents at the 2- and 6-posi-
tions are designed as linking groups to produce the macrocy-
cle, whereas the two X groups at the 2- and 6-positions and
the Z groups at the 4- and 8-positions remain in mutually
perpendicular geometrical relationships and are used as the
peripheral functionalities. Accordingly, we expected that the
2,6-diethynyl hydrindacene (Z)-1 would function as a suita-
Scheme 2. Preparation of 4,8-disubstituted hydrindacene derivatives 9a–
d. a) MeI, K2CO3, 2-butanone, 658C, 81%; b) paraformaldehyde, 8%
HBr in AcOH, 508C, 83%; c) hn, N-bromosuccinimide (NBS), CH2Cl2,
408C, 98%; d) diethyl malonate, NaOEt, EtOH/PhH (for 9a) or EtOH
(for 9b), reflux, 53% for 9a; 77% for 9b; e) 2-(tributylstannyl)thio-
phene, [Pd
nacol ester, Pd
(SPhos), THF, 408C, 91%.
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
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Acetylene Macrocycles
FULL PAPER
photoirradiation with a halogen lamp afforded tetrabromide
8a[19] in 66% total yield. Treatment of the tetrabromides
8a,b with diethyl malonate along with NaOEt in EtOH[24]
gave the tetraesters 9a,b. The 4,8-dithienyl and distyryl de-
rivatives 9c,d were prepared by Stille or Suzuki–Miyaura
coupling of the dibromo derivative 9b with 2-(tributylstan-
nyl)thiophene or trans-2-styreneboronic acid pinacol
ester.[25] The molecular structures of 9a,c,d were confirmed
by crystallography and are given in Figure 1.
methods for the introduction of the ethynyl groups, as
shown in Scheme 3. These three routes were: A) the chlor-
oethynylation of enolates as developed by Kende et al.,[26]
B) the conversion of formyl groups to ethynyl groups by the
Corey–Fuchs method[27] following selective reduction of the
gem-diester to the monoaldehyde as developed by Burton
and co-workers,[28] or C) the conversion of formyl groups to
ethynyl groups by the Ohira–Bestmann method.[29]
Initially, 2,6-diethynyl derivative (Z)-1a was prepared by
means of chloroethynylation at the 2,6-positions of (E/Z)-
10a (route A). Decarboxylation of 9a in DMSO gave the
diester (E/Z)-10a. Treatment of (E/Z)-10a with lithium dii-
sopropylamide (LDA) at À408C and the subsequent addi-
tion of an excess amount of dichloroacetylene[26] in diethyl
ether at À208C gave an isomeric mixture of the 2,6-bis(-
chloroethynyl) derivative (E)- and (Z)-11a in 20 and 15%
yields, respectively. The structure of (Z)-11a was confirmed
through X-ray crystallography after chromatographic sepa-
ration of the isomers (Figure 2). Dechlorination[26] of (E)-
11a and (Z)-11a with copper gave (E)-1a and (Z)-1a in 39
and 71% yields, respectively.
Secondly, (Z)-1a was also prepared by an alternative
method through the selective reduction of the gem-diester
to the monoaldehyde by means of the process developed by
Burton et al.,[28] followed by Corey–Fuchs ethynylation[27]
(route B). Reduction of the tetraester 9a with an excess
amount of diisobutylaluminium hydride (DIBAL-H) at
À788C gave an isomeric mixture of the 2,6-dialdehyde (E/
Z)-12a in a ratio of 1:1. Treatment of (E/Z)-12a with CBr4/
Figure 1. X-ray structures of 4,8-disubstituted hydrindacene derivatives
9a, 9c, and 9d. Atoms in thienyl groups of 9c are positionally disor-
dered.
Preparation of 2,6-diethynyl hydrindacene monomer units:
The monomer unit, 2,6-diethynyl derivative (Z)-1a, was pre-
pared from the tetraester 9a by using one of three possible
Scheme 3. Preparation of monomer units (Z)-1a–d. a) NaCl, H2O, DMSO, 1708C, 69%; b) LDA, hexamethylphosphoramide (HMPA), THF, À788C,
then dichloroacetylene in Et2O,[24] À20 to 258C, 20% for (E)-11a, 15% for (Z)-11a; c) Cu powder, AcOH/THF, 708C, 39% for (E)-1a, 71% for (Z)-1a
(from (Z)-11a) and 71% for (Z)-1a (from (Z)-14a); d) DIBAL-H, CH2Cl2, À788C; e) CBr4, PPh3, CH2Cl2, 0 to 258C, 30% for (E)-13a, 31% for (Z)-
13a (two steps, respectively); f) KHMDS, THF, À788C, 92% for (Z)-14a; g) dimethyl 1-diazo-2-oxopropylphosphonate (Ohira–Bestmann reagent),
EtONa, THF À788C, then (E/Z)-12a–d, À78 to 258C, 40% for (E/Z)-1a; 38% for (E/Z)-1b; 45% for (E/Z)-1c; 53% for (E/Z)-1d (1:1, two steps, re-
spectively); h) 1) (Z)-1a, LiOH, H2O/THF, 238C; 2) SOCl2, CH2Cl2, 408C; 3) n-decanol or CH
29% for (Z)-1 f (three steps, respectively).
3CATHUGNTERNGNUN(OCH2CH2)3OH, Et3N, CH2Cl2, 218C, 49% for (Z)-1e,
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H. Kawai et al.
Figure 2. X-ray structures of hydrindacene derivatives.
Scheme 4. Macrocyclization of diethynylhydrindacenes (Z)-1a–f.
[27]
PPh3 gave the 2,6-bis(dibro-
Table 1. Reaction conditions and yields for macrocycles 1a–f.
moethenyl) derivative (E)- and
(Z)-13a in 30 and 31% yields,
respectively. After chromato-
graphic separation of the iso-
mers, treatment of (Z)-13a
with potassium bis(trimethylsi-
lyl)amide (KHMDS) and the
subsequent debromination of
(Z)-14a with copper gave (Z)-
1a in 92% yield. The struc-
tures of (E)-13a, (Z)-14a and
c [mm]
Isolated yields[a] [%]
2 (n=2)
3 (n=3)
4 (n=4)
Oligomer (n=5–6)
Total
1a
1a
1a
1b
1c
1d
1e
1 f
1
10
100
10
10
5
31
42
3
39
52
64
56
18
12
35
13
26
22
13
25
11
4
5
6
8
8
6
55
91
29
90
90
77
81
29
12
8
13
8
–
–
–
–
–
–
10
10
[b]
[a] The product ratios were determined by GPC separation and quantitation. [b] The oligomer could not be
obtained due to its solubility to water.[32]
(Z)-1a
were
confirmed
through X-ray crystallography
and are presented in Figure 2.
starting material (Z)-1 used in the macrocyclization reac-
Lastly, (Z)-1a was more readily prepared by treating the
dialdehyde (E/Z)-12a with Ohira–Bestmann reagent[29]
(route C). Upon addition of (E/Z)-12a to a solution of
Ohira–Bestmann reagent pretreated with NaOEt in THF at
À788C,[30] a 1:1 isomeric mixture of the 2,6-diethynyl deriva-
tive (E/Z)-1a was successfully produced. A similar reaction
scheme that uses K2CO3 as a base in MeOH at room tem-
perature only gave the retro-Claisen product (E/Z)-10a. The
4,8-dibromo-, 4,8-bis(2-thienyl)-, and 4,8-distyryl derivatives
(E/Z)-1b–d were also prepared by route C. The E and Z
isomers of 1a–d were separated by high-performance liquid
chromatography (HPLC).
tion, an effect that is highlighted by the relatively high pro-
portion of dimer formed in the case of 1d, for which a con-
centration of only 5 mm was employed. When either 1 or
10 mm solutions of (Z)-1a were used, the dimer 2a was the
major product, although the total yield of macrocycles was
lower with the 1 mm solution. At a higher concentration of
(Z)-1a (100 mm), a greater proportion of the larger oligom-
ers resulted, with trimer 3a as the major product. In con-
trast, treatment of (Z)-1a (10 mm) with CuACTHNURGTNEUNG(OAc)2 and CuCl
in pyridine resulted in the formation of a complex mixture
of products, and macrocycles 2a–4a were isolated in low
overall yields of 10%.
Modification of the ester groups on the hydrindacene
units of (Z)-1a offers an opportunity to add a wide variety
of moieties to these macrocycles. Saponification of ethyl
ester groups of (Z)-1a with LiOH and subsequent treat-
ments with SOCl2 and 1-decanol or triethyleneglycol mono-
methyl ether gave the decyl ester 1e or the triethyleneglycol
(TEG) ester 1 f.
Macrocyclization of the bromo monomer (Z)-1b or thien-
yl monomer (Z)-1c (10 mm) produced mixtures that con-
tained various sizes, including 2b–4b or 2c–4c, results that
are somewhat similar to those observed when using (Z)-1a.
Following the reaction of styryl monomer (Z)-1d suspended
in MeCN, macrocyclic dimer 2d was preferentially produced
along with a smaller amount of trimer 3d. This distribution
of products was likely obtained because the macrocycliza-
tion of (Z)-1d proceeds under quasi-high dilution conditions
due to the low solubility of this monomer in MeCN. Macro-
cyclization of monomers (Z)-1e and (Z)-1 f under similar
coupling conditions gave macrocyclic dimers 2e and 2 f as
the major products,[32] along with trimers 3e and 3 f.
Macrocyclization of 2,6-diethynyl hydrindacenes (Z)-1a–d:
Macrocyclization of the methoxy monomer (Z)-1a (10 mm)
under modified Eglinton coupling[31] conditions using Cu-
ACHTUNGTRENNUNG(OAc)2 in MeCN successfully produced a series of macrocy-
cles including dimer 2a, trimer 3a, and tetramer 4a, as well
as higher oligomers in good total yields (Scheme 4, Table 1).
The size distribution of the resulting macrocycles in these
crude mixtures varied according to the concentration of the
Dimers 2a–d were less soluble than the other macrocycles
in common organic solvents and were easily isolated by
washing the reaction mixtures with CHCl3. The mother liq-
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Acetylene Macrocycles
FULL PAPER
uors were further separated by gel-permeation chromatogra-
phy (GPC) and macrocycles 3 and 4 were thus also isolated
and characterized by mass spectroscopy.
Peripheral modification of hydrindacene-based macrocycles:
Modification of the ester groups on the macrocycles offers a
means to vary some of the characteristic properties of these
compounds. In this work, we chose to use transesterification,
which allowed us to readily modify the ester groups by reac-
tion with various alkanols. One result of such transesterifica-
tion can be the tuning of the solubility of a macrocycle in
various solvents. Although the macrocycles with long ester
chains (2e,f and 3e,f) were prepared by macrocyclization of
the corresponding monomers (Z)-1e or (Z)-1 f as shown in
Scheme 4, we found that transesterification of macrocycles
can be achieved using Oteraꢁs distannoxane catalyst[33]
(Scheme 5). The ethyl groups on the ester substituents of
Figure 3. X-ray structures of a) 2a·hexane solvate and b) 2b, and
c,d) their packing structures. A solvated hexane molecule in the crystal
of 2a is located outside the cavity and omitted for clarity.
tions on the five-membered rings of the hydrindacene skele-
ton and are separated by a distance of 6.76 or 7.14 ꢂ (for 2a
and 2b, respectively). The resulting cavity in both 2a and 2b
was found to be empty in the crystal structure, thus indicat-
ing that the cavity is too small to include any guest solvent
molecules.
Scheme 5. Transesterification of macrocycles by using Oteraꢁs distannox-
ane.[33]
macrocycles 2 and 3 were easily modified by using Oteraꢁs
distannoxane[33] and 1-dodecanol, 1-decanol, or triethylene-
glycol monomethyl ether. The resulting peripherally modi-
fied macrocycles with long ester chains (2g–i and 3g,h)
demonstrated improved solubility in common organic sol-
vents.
In trimers 3a–c, the macrocyclic frame adopts not a hex-
agonal shape with (pseudo-)D3h symmetry, but rather a dis-
torted rectangular conformation (Figure 4). Two hydrinda-
cene units face one another nearly in parallel at a distance
of 7.70, 8.47, or 8.04 ꢂ for 3a, 3b, and 3c, respectively, and
are positioned at close to right angles to the third hydrinda-
cene unit. The distances spanned by the hydrindacene and
butadiyne units along the long axis of the void are 14.0,
13.4, and 13.8 ꢂ for 3a, 3b, and 3c, respectively. The buta-
diyne moieties along the central portion of the long axis
occupy pseudoequatorial positions, thereby resulting in the
rectangular shape of the macrocycles. X-ray analysis further
demonstrated that one or more solvent molecules, such as
hexane, CHCl3, or cyclohexane, were captured within the
cavities of these trimers. Macrocycles 3a,c, with methoxy or
thienyl groups as vertical substituents, stacked into a colum-
nar structure with an offset packing, thus avoiding intermo-
lecular contact between the methoxy or thienyl groups (Fig-
ure 4a,c). Solvent molecules in the 3a crystals appear to be
strongly held within the macrocycle cavity and were not re-
moved even under vacuum, presumably due to buttressing
effects by the neighboring methoxy groups. Interestingly, the
X-ray structures of hydrindacene-based macrocycles 2–4:
Single crystals of a quality suitable for X-ray crystallography
were obtained for dimers 2a,b, trimers 3a,b,c, and tetramer
4b, although attempts to obtain crystal samples from the
styryl macrocycles 2d and 3d were unsuccessful. X-ray anal-
yses of macrocycles 2a,b and 3a,b,c provided unambiguous
confirmation of their structures and demonstrated a well-or-
dered array of functionalities that consisted of a peripheral
ester along with methoxy (for 2a and 3a), bromo (for 2b
and 3b), or thienyl groups (for 3c) vertical to the macrocy-
clic ring.
The structures determined by X-ray analysis for the
dimers 2a and 2b indicated two hydrindacene units facing
one another in a parallel fashion with a distance between
the two units of 7.86 (for 2a) or 7.70 ꢂ (for 2b; Figure 3).
The butadiyne moieties are arranged in pseudoaxial posi-
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H. Kawai et al.
Figure 4. X-ray structures (top) and their packing structures (middle and bottom) of a) 3a·hexane solvate, b) 3b·(cyclohexane)2 solvate, and c) 3b·-
A
2.5·ACHTUNGTRENNUNG(benzene)2.5 solvate. One methoxy group and one of the ethyl groups of 3a are disordered. Cyclohexanes in 3b are disordered. Five thienyl
macrocycle 3b instead stacked into a tubelike structure with
a 1D channel-like cavity, in which the three butadiynes and
six bromo groups of neighboring macrocycles are in close
proximity at distances of 3.30 to 3.66 ꢂ (Figure 4b). The
highly disordered packing of cyclohexane molecules within
this cavity indicates that such solvent molecules do not un-
dergo specific interactions with the columnar channel.
structure in which the orientation of the butadiyne groups is
pseudoaxial, could account for the observed shrunken tub
structure taking precedence over an open-extended struc-
ture with a larger cavity.
Spectroscopic characterization of the hydrindacene-based
macrocycles
The tetramer 4b has a tub-shaped structure, in which all
butadiyne moieties are located at a pseudoaxial position on
the cyclopentene rings (Figure 5). Four molecules of CH2Cl2
are trapped in the cavity of the tub. Interhalogen interac-
tions between adjacent bromo groups (at a distance of 5.09
and 5.31 ꢂ), as well as a preferred conformation for the
1H NMR spectra: 1H NMR spectra of all macrocycles in
CDCl3 indicated a high degree of symmetry (Dnh) in these
species (Figure 6). Evidently the high symmetry (D3h) of the
trimer 3a in solution differs from the pseudo-C2v symmetry
1
adopted in the crystal. Although the H NMR spectrum of
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Acetylene Macrocycles
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It should be noted that the signals from dimers 2a–d
appear at shifted positions relative to the corresponding sig-
nals of the larger macrocycles 3a–d and 4a–c, as well as
those of the precursor species 1a–d. Notably, one of the sig-
nals from the protons of the five-membered ring of 2a–d
(Hb) appears at an upfield-shifted position around d=
3.5 ppm, an effect that can be attributed to the conforma-
tional rigidity of the hydrindacene units in the dimer. When
the ester group is located at the pseudoaxial position on the
five-membered ring of a hydrindacene unit, the protons
(Hb) of five-membered rings near the ester group experience
a stronger deshielding effect from the carbonyl of the ester
group than from the alkyne group, thereby causing those
signals to appear at lower-field positions (see the Supporting
Information). The larger macrocycles 3a–d and 4a–c, as
well as the precursor species 1a–d, all of which have moder-
ately flexible five-membered rings, exhibit this effect, al-
though the rigid macrocycles 2a–d with ester groups at the
pseudoequatorial position do not. Our conclusion that the
population of ester groups that actually occupies pseudoax-
ial positions is greater in the monomers 1, trimers 3, and tet-
ramers 4 than in the dimers 2
Figure 5. X-ray structure of 4b·ACTHNUTRGNE(UNG CH2Cl2)4 and its packing structure. Hy-
drogen atoms are omitted for clarity.
was also confirmed by observ-
ing that the methylene protons
(Hc) of the ethyl ester groups
of 1a–d, 3a–d, and 4a–c
appear at upfield-shifted posi-
tions (at d=4.1 to 4.2 ppm)
due to shielding from the ben-
zene rings of the hydrindacene
unit relative to the same pro-
tons in 2a–d (at d=4.2 to
4.3 ppm). These observations
indicate that dimers 2a–d pos-
sess a rigid macrocyclic frame-
work, whereas trimers 3 and
tetramers 4, as well as mono-
mers 1, have
a moderately
flexible structure based on flip-
ping of the five-membered
rings.
Figure 6. 1H NMR spectra of a) monomer (Z)-1c; b) macrocycles 2c, c) 3c, and d) 4c; e) monomer (Z)-1d;
f) macrocycles 2d; and g) 3d in CDCl3 at 295 K.
UV-visible and fluorescence
spectra: The spectroscopic
properties of the macrocyclic
3a did not change upon lowering the solution temperature
to À928C in CD2Cl2, the most stable conformer of 3a is
likely to adopt a rectangular shape with C2v symmetry. Ac-
cordingly, this apparent D3h symmetry is achieved by means
of a rapid degenerate conformational change accompanied
by flipping of the alicyclic rings of the hydrindacene units,
since a hexagonal shape would force all alicyclic rings to
adopt an unstable flattened conformation and thus is not fa-
vored for this macrocycle (see Figure S1 in the Supporting
Information). The apparent high symmetry of the tetramer
4a also originates in the rapid conformational changes be-
tween two degenerate folded tub forms.
dimers 2c,d, trimers 3c,d, and monomers 1c,d are shown in
Figure 7. The molar absorption coefficients for each species
show multiplication by the number of chromophoric units in
the structure. From the normalized data obtained by instead
dividing by the number of chromophoric units (see the Sup-
porting Information), it is evident that the molar absorption
per hydrindacene unit shows a hypochromic shift in dimers
2c,d relative to monomers 1c,d. Slight blueshifts were ob-
served in the UV-visible spectra of the dimers 2a–d relative
to 1a–d (3, 1, 5, and 5 nm for 2a, 2b, 2c, and 2d, respective-
ly; Table 2). Additionally, slight redshifts were observed in
the fluorescence spectrum of dimer 2c relative to 1c and 3c
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4519

H. Kawai et al.
mately 1.0 for 9d in CH2Cl2, 0.17 for 2d, 0.61 for 9d as a
solid, respectively). These differences might be due to the
fact that the excited-state energy of the distyrylbenzene
chromophore is lower than that of the butadiyne unit.[37]
Cyclic voltammetry: The interunit interactions[34] within the
macrocyclic dimer were also evident in the redox properties
of the methoxy macrocycles 2a–4a. These macrocycles,
along with reference compounds 1a, 9a, and 1,4-dimethoxy-
durene, were analyzed by cyclic voltammetry in CH2Cl2 that
contained 0.1m Bu4NPF6 as
a supporting electrolyte
(Figure 8). The 4,8-dimethoxyhydrindacene derivatives 1a–
Figure 7. UV/Vis (solid line) and fluorescence spectra (dashed line) of
a) (E)-1c, 2c, and 3c; and b) (E)-1d, 2d, and 3d in CH2Cl2.
Table 2. Optical data of monomers 1a–d and macrocycles 2a–d and 3a–
d.
Absorption
lmax [nm]
Emission
lem [nm]
Stokes shift
[nm]
3a
2a
(Z)-1a
3b
2b
(E)-1b
3c
2c
(E)-1c
3d
2d
284
284
283
286
286
285
295
291
296
339
341
346
–
–
328
–
–
–
353, 366
360, 374
352, 366
395, 417
395, 417
395, 417
–
–
49
–
–
–
58
69
56
56
54
49
Figure 8. Cyclic voltammograms of a) 2a (black line) and b) 3a (gray
line) measured in CH2Cl2 containing 0.1m nBu4NPF6 (Pt electrode, scan
rate: 100 mVsÀ1).
(E)-1d
4a and 9a show reversible oxidation waves around +1.35 V
(E1/2 = +1.29 and +1.42 V for 2a, +1.37 V for 3a, +1.36 V
for 4a, +1.35 V for 1a, and +1.34 V for 9a versus SCE). In
contrast, 1,4-dimethoxydurene shows irreversible oxidation
peaks at a higher potential (E1/2 = +1.48 V). This can be ac-
counted for by considering that the methoxy groups in this
species cannot adopt coplanar arrangements with the ben-
zene nuclei in the cationic state due to steric hindrance, so
that a positive charge cannot be delocalized over the me-
thoxy lone pair.[39] Thus, the reversibility upon oxidation of
the hydrindacene derivatives 1a–4a and 9a can be attribut-
ed to the decrease in steric hindrance around the methoxy
groups on the benzene ring, which is achieved by binding
neighboring alkyl groups on the aromatic ring into alicyclic
structures.[39a–c]
(8 nm redshifted from both 1c and 3c). The methoxy and
bromo derivatives 2a,b and 3a,b are nonfluorescent.
Since the distances of 7.7 to 7.9 ꢂ between the two hy-
drindacene units in the dimers 2a–d are too great to allow
direct interaction in a through-space manner,[34] the larger
Stokes shift observed in 2c relative to trimer 3c might be at-
tributed to the excited-state coupling of the hydrindacene
chromophores of 2 and the butadiyne units arranged verti-
cally between the two hydrindacene units. Due to the over-
lapping of the absorption band of the butadiyne and the hy-
drindacene chromophore in 1a–c (at lmax ꢀ270 nm for each
relevant compound[35,36]), their excited states might be effec-
tively delocalized over the entire molecule in the dimer
structure (see the calculated molecular orbitals (MOs) in
Figure 9 below).[37]
A coupled excited state appears to be energetically unfav-
orable in the case of the styryl macrocycles 2d and 3d. In-
teractions among hydrindacene units were not observed
even in dimer 2d, although a series of styryl-substituted hy-
drindacene derivatives (1d, 2d, 3d, and 9d) efficiently emit
fluorescence bands in the region of 400 nm both in solution
and in the solid state (f=0.89 for 1d, 0.92 for 2d, approxi-
It is interesting to note that dimer 2a shows two well-re-
solved and reversible waves at Eox = +1.29 and +1.42 V,
whereas trimer 3a and tetramer 4a show only one reversible
wave around +1.36 V. Because each hydrindacene unit
should undergo one-electron oxidation at this potential, it is
highly likely that there is an electronic interaction between
the two hydrindacene units in the cation radical 2a+ , which
C
makes further oxidation of 2a+ to the dication 2a2+ diffi-
C
cult. Considering that the analogous tetramethoxy-
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Acetylene Macrocycles
FULL PAPER
ACHTUNGTRENNUNG[7.7]paracyclophane derivative, with an interplanar distance
of 7.38 ꢂ, shows only one reversible peak,[34c] the potential
difference of 0.13 V observed in dimer 2a (with an interpla-
nar distance of 7.86 ꢂ between its two hydrindacene units)
presumably does not stem from through-space interaction,[34]
but rather from through-bond interaction. The absence of
such bond interactions in trimer 3a or tetramer 4a can be
explained by considering their flexible structures. Thus, a
rigid macrocycle framework that favors through-bond inter-
actions is necessary for the stepwise oxidation observed in
the dimer.
Theoretical calculation: To elucidate the observed electronic
interactions between the two hydrindacene units in dimer
2a, we performed density functional theory (DFT) calcula-
tions with regard to both dimers 2a and 2c, as well as radi-
cal cation 2a+ . The optimized geometric parameters of
C
these macrocycles calculated at the B3LYP/6-31G* level[40,41]
are in good agreement with the experimental data obtained
for their solid-state structures. Orbital-coefficient contours
of the HOMOs and LUMOs of dimers 2a,c demonstrate
that a significant interaction exists between the two hydrin-
dacene units through the butadiyne units (Figure 9). The
through-bond coupling between the orbitals of the substitut-
ed benzene portions of the hydrindacene units and those of
the butadiyne units yields the following: bonding
HOMOÀ1, anti-bonding HOMO, bonding LUMO, and anti-
bonding LUMO+1. The calculated gaps between HOMO
and HOMOÀ1 are 0.10 eV (LUMO and LUMO+1:
0.11 eV) for 2a and 0.04 eV (LUMO and LUMO+1:
0.07 eV) for 2c. In the optimized structure of radical cation
2a+ , orbital-coefficient contours of the singly occupied mo-
C
lecular orbital (SOMO) demonstrate that a similar interac-
tion exists between the two hydrindacene units through the
butadiyne units, thus suggesting electronic delocalization in
the one-electron-oxidated state (Figure S3 in the Supporting
Information).
Figure 9. Pictorial presentations of HOMOs and LUMOs in a) macrocy-
clic dimers 2a and b) 2c calculated at the B3LYP/6-31G* level.
able solubility and subsequent assembly into tubelike struc-
tures when in solution, with the result of adjusting their af-
finity towards membranes[2b,i,42] or other substrate surfa-
ces.[2d] The introduction of p-conjugated groups, such as
styryl and thienyl groups (as in 2c,d and 3c,d), or hydrogen-
bonding groups such as amides[17,18] to the 4,8-positions of
the hydrindacene unit could allow the possibility of p-conju-
gated or self-assembled nanotubes. We are currently study-
ing various functionalization options with the goal of assem-
bling such macrocycles into tubular structures.
Conclusion
We have shown that the macrocyclization of a series of (Z)-
2,6-diethynyl hydrindacenes ((Z)-1) with functional groups
at mutually perpendicular positions results in the formation
of novel macrocycles with directionally persistent peripheral
functionalities as a result of rotational fixation of the hydrin-
dacene units. Analysis of the resulting macrocycles has dem-
onstrated several interesting characteristics, including that
the two hydrindacene units in the macrocyclic dimers (2)
might interact electronically through their butadiyne moiet-
ies. The macrocyclic trimers (3) exhibit moderate geometri-
cal flexibility and possess a central cavity that is large
enough to accommodate molecules of common organic sol-
vents. Furthermore, peripheral ester groups were readily
modified to introduce hydrophobic or hydrophilic chains
through the use of Oteraꢁs distannoxane catalyst. Some of
these modified macrocycles could have the capacity for tun-
Experimental Section
General method for the macrocyclization of (Z)-1: A mixture of (Z)-1
and CuACHTNURGTNE(NUG OAc)2 (20 equiv) in CH3CN was heated at reflux for 25 h. After
the mixture was cooled, water was added, and the solution was extracted
with CHCl3. The organic layer was washed with water and brine, dried
over Na2SO4, and then filtered. A small amount of CHCl3 was added to
the white solid obtained by evaporation of the solvent to give a suspen-
sion. Macrocycles 2a–d were obtained by filtration of the suspension.
Chem. Eur. J. 2013, 19, 4513 – 4524
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4521

H. Kawai et al.
Other macrocycles 3a–d, 4a–c, and higher oligomers were separated by
GPC (eluting with CHCl3) of the filtrate.
(1.9 mg, 11%), and higher oligomer (0.7 mg, 4%) as white solids, respec-
tively.
Dimer 2c: M.p. 255.0–259.08C; 1H NMR: d=7.39 (d, J=5.1 Hz, 4H),
7.12 (dd, J=3.6 Hz, 5.1 Hz, 4H), 7.06 (d, J=3.6 Hz, 4H), 4.20 (q, J=
7.1 Hz, 8H), 3.52 (d, J=15.4 Hz, 4H), 3.45 (d, J=15.4 Hz, 8H), 1.28 ppm
(t, J=7.1 Hz, 12H); 13C NMR: d=171.12, 139.01, 138.96, 128.19, 127.18,
127.05, 125.70, 79.82, 67.14, 62.17, 49.41, 44.59, 14.07 ppm; IR (KBr): n˜ =
3101, 2977, 2924 1736, 1235, 1042, 701 cmÀ1; MS (FD): m/z (%): 1027
[M++3] (23), 1026 [M++2] (47), 1025 [M++1] (72), 1024 [M+] (100);
HRMS (FD): m/z: calcd for C60H48O8S4: 1024.2253; found: 1024.2232.
Methoxy macrocycles 2a–4a with ethyl esters: Macrocycles 2a–4a were
prepared from (Z)-1a (28 mg, 68 mmol) and CuACTHNURGTNEUNG(OAc)2 (220 mg,
1.22 mmol) in CH3CN (5.0 mL). GPC separation of the crude product
gave dimer 2a (11.6 mg, 46%), trimer 3a (9.8 mg, 39%), tetramer 4a
(1.5 mg, 6%), and higher oligomer (2.5 mg, 10%) as white solids, respec-
tively.
Dimer 2a: M.p. 269.0–270.08C; 1H NMR: d=4.27 (q, J=7.2 Hz, 8H),
3.73 (s, 12H), 3.44 (d, J=15.6 Hz, 8H), 3.38 (d, J=15.6 Hz, 8H),
1.34 ppm (t, J=7.2 Hz, 12H); 13C NMR: d=171.35, 148.23, 131.18, 79.27,
66.66, 62.21, 59.84, 50.13, 41.96, 14.15 ppm; IR (KBr): n˜ =2978, 1740,
1482, 1290, 1264, 1236, 1090, 1050 cmÀ1; MS (FD): m/z (%): 817 [M++1]
(55), 816 [M+] (100), 408 [M2+] (18); HRMS (FD): m/z: calcd for
C48H48O12: 816.3146; found: 816.3136; elemental analysis calcd (%) for
C48H48O12·H2O: C 69.05, H 6.04; found: C 69.25, H 6.30.
Trimer 3a: M.p. 192.0–194.08C; 1H NMR: d=4.22 (q, J=7.2 Hz, 12H),
3.74 (s, 18H), 3.56 (d, J=15.6 Hz, 12H), 3.31 (d, J=15.6 Hz, 12H),
1.29 ppm (t, J=7.2 Hz, 18H); 13C NMR: d=171.23, 148.06, 131.73, 79.72,
66.62, 62.29, 59.90, 49.11, 41.87, 14.05 ppm; IR (KBr): n˜ =2980, 1738,
1482, 1292, 1234, 1184, 1090, 1048 cmÀ1; MS (FD): m/z (%): 1226 [M+
+2] (46), 1225 [M++1] (85), 1224 [M+] (100), 613 [M2+] (25); HRMS
(FD): m/z: calcd for C72H72O18: 1224.4719; found: 1224.4695; elemental
analysis calcd (%) for C72H72O18·H2O: C 69.55, H 6.00; found: C 69.46, H
6.26.
Tetramer 4a: 1H NMR: d=4.23 (q, J=7.2 Hz, 16H), 3.75 (s, 24H), 3.58
(d, J=15.6 Hz, 16H), 3.34 (d, J=15.6 Hz, 16H), 1.31 ppm (t, J=7.2 Hz,
24H); 13C NMR: d=171.28, 148.05, 131.69, 79.74, 66.6a, 62.30, 59.88,
49.02, 41.94, 14.07 ppm; IR (KBr): n˜ =2928, 1738, 1480, 1292, 1234, 1186,
1090, 1038 cmÀ1; MS (FD): m/z (%): 1634 [M++2] (42), 1633 [M++1]
(100), 1632 [M+] (66), 817 [M2++1] (39), 816 [M2+] (27); HRMS (FD):
m/z: calcd for C96H96O24: 1632.6292; found: 1632.6259.
Trimer 3c: M.p. 186.0–189.08C; 1H NMR: d=7.38 (dd, J=0.75 Hz,
5.1 Hz, 6H), 7.10 (dd, J=3.6 Hz, 5.1 Hz, 6H), 7.00 (dd, J=0.75 Hz,
3.6 Hz, 2H), 4.15 (q, J=7.1 Hz, 12H), 3.64 (d, J=15.8 Hz, 12H), 3.42 (d,
J=15.8 Hz, 4H), 1.22 ppm (t, J=7.1 Hz, 18H); 13C NMR: d=171.22,
138.92, 138.78, 127.54, 127.18, 127.07, 125.71, 79.73, 66.57, 62.20, 48.54,
44.86, 13.40 ppm; IR (KBr): n˜ =3106, 2977, 1736, 1235, 1046, 699 cmÀ1
;
MS (FD): m/z (%): 1540 [M++4] (27), 1539 [M++3] (55), 1538 [M++2]
(90), 1538 [M++1] (100), 1537 [M+] (100), 1463 [M+ÀCO2Et] (22);
HRMS (FD): m/z: calcd for C90H72O12S6: 1536.3348; found: 1536.3356.
Tetramer 4c: M.p. 220.0–223.08C; 1H NMR: d=7.38 (dd, J=0.72 Hz,
4.9 Hz, 8H), 7.11 (dd, J=3.5 Hz, 4.9 Hz, 8H), 7.01 (dd, J=0.72 Hz,
3.5 Hz, 8H), 4.14 (q, J=7.1 Hz, 16H), 3.68 (d, J=15.9 Hz, 16H), 3.42 (d,
J=15.9 Hz, 16H), 1.22 ppm (t, J=7.1 Hz, 24H); 13C NMR: d=171.21,
139.02, 138.67, 127.33, 127.23, 127.07, 79.50, 66.52, 62.25, 48.56, 44.91,
14.00 ppm; IR (KBr): n˜ =3101, 3074, 2976, 2925, 1736, 1236, 1041,
701 cmÀ1; MS (FD): m/z (%): 2054 [M++5] (30), 2053 [M++4] (50), 2052
[M++3] (80), 2051 [M++2] (100), 2050 [M++1] (100), 1540 [M+] (65),
1977 [M++1ÀCO2Et] (33), 1976 [M+ÀCO2Et] (30); HRMS (FD): m/z:
calcd for C120H72O16S8: 2048.4464; found: 2048.4442.
Styryl macrocycles 2d–3d with ethyl esters: Macrocycles 2d–3d were
prepared from (Z)-1d (24.7 mg, 45 mmol) and CuACTHNURGTNEUNG(OAc)2 (165 mg,
0.91 mmol) in CH3CN (9.0 mL). Benzene (5 mL) was added to the crude
product after workup, and the mixture was filtered to give dimer 2d
(10.5 mg, 43%) as a white solid. The filtrate was re-precipitated from
CHCl3/hexane to give 2d (2.9 mg, 12%). GPC separation of the filtrate
gave dimer 2d (2.3 mg, 9%, total 64%), trimer 3d (3.2 mg, 13%), and
higher oligomer (3.6 mg, 15%) as white solids, respectively.
Bromo macrocycles 2b–4b with ethyl esters: Macrocycles 2b–4b were
prepared from (Z)-1b (35 mg, 69 mmol) and CuACTHNURGTNEUNG(OAc)2 (252 mg,
1.39 mmol) in CH3CN (6.9 mL). CHCl3 (3 mL) was added to the crude
product after workup, and the mixture was filtered to give dimer 2b
(11.4 mg, 33%) as a white solid. GPC separation of the filtrate gave
dimer 2b (2.2 mg, 6%, total 39%), trimer 3b (9.2 mg, 26%), tetramer 4b
(4.1 mg, 12%), and higher oligomer (4.6 mg, 13%) as white solids, re-
spectively.
Dimer 2b: M.p. 240–2428C (decomp); 1H NMR: d=4.28 (q, J=7.1 Hz,
8H), 3.56 (d, J=15.4 Hz, 8H), 3.45 (d, J=15.4 Hz, 8H), 1.35 ppm (t, J=
7.1 Hz, 12H); 13C NMR: d=170.41, 140.68, 115.53, 78.94, 67.20, 62.50,
48.38, 46.47, 14.13 ppm; IR (KBr): n˜ =2977, 2925, 2172, 1740, 1443, 1066,
908, 857 cmÀ1; MS (FD): m/z (%): 1016 [M++8] (27), 1015 [M++7] (33),
1014 [M++6] (67), 1013 [M++5] (42), 1012 [M++4] (100), 1011 [M++3]
(31), 1010 [M++2] (68), 1016 [M+] (22); elemental analysis calcd (%) for
C44H36 Br4O8·H2O: C 51.29, H 3.72; found: C 51.23, H 3.55.
Trimer 3b: M.p. 212–2148C (decomp); 1H NMR: d=4.25 (q, J=7.1 Hz,
12H), 3.67 (d, J=16.1 Hz, 12H), 3.42 (d, J=16.1 Hz, 12H), 1.31 ppm (t,
J=7.1 Hz, 18H); 13C NMR: d=170.73, 140.57, 115.13, 79.48, 66.94, 62.60,
47.03, 46.75, 14.03 ppm; IR (KBr): n˜ =2978, 2924, 2172, 1739, 1443, 1236,
1185, 1061, 799 cmÀ1; MS (FD): m/z (%): 1524 [M++12] (28), 1522 [M+
+10] (59), 1520 [M++8] (78), 1518 [M++6] (100), 1516 [M++4] (78),
1514 [M++2] (41), 11512 [M+] (13); elemental analysis calcd (%) for
C66H54Br6O18: C 52.20, H 3.58; found: C 52.39, H 3.86.
Tetramer 4b: M.p. 180–1838C (decomp); 1H NMR: d=4.27 (q, J=
7.1 Hz, 16H), 3.65 (d, J=16.1 Hz, 16H), 3.48 (d, J=16.1 Hz, 16H),
1.34 ppm (t, J=7.1 Hz, 24H); 13C NMR: d=170.77, 140.53, 115.25, 79.65,
66.93, 62.63, 47.09, 46.80, 14.11 ppm; IR (KBr): n˜ =2925, 2172, 1740,
1631, 1442, 1236, 1058, 799 cmÀ1; MS (FD): m/z (%): 2024.4 [M+] (100),
1013.1 [M2+] (43); HRMS (FD): m/z: calcd for C88H72Br8O16: 2015.8287;
found: 2048.4442.
Dimer 2d: M.p. 241.5–242.58C; 1H NMR: d=7.49 (d, J=7.3 Hz, 8H),
7.36 (t, J=7.1 Hz, 8H), 7.28 (d, J=7.1 Hz, 4H), 7.16 (d, J=16.8 Hz, 4H),
6.77 (d, J=16.8 Hz, 4H), 4.30 (q, J=7.1 Hz, 8H), 3.64 (d, J=15.0 Hz,
8H), 3.53 (d, J=15.0 Hz, 8H) 1.36 ppm (t, J=7.1 Hz, 12H); 13C NMR:
d=171.47, 137.74, 137.33, 133.07, 129.65, 128.73, 127.96, 126.55, 125.41,
79.38, 66.65, 62.32, 49.59, 44.39, 14.18 ppm; IR (KBr): n˜ =3055, 3025,
2922, 2853, 2169, 1736, 1631, 1448, 1232, 1046, 968 cmÀ1; MS (FD): m/z
(%): 1106 [M++2] (41), 1105 [M++1] (94), 1104 [M+] (100), 553 [M2+
+1] (24), 552 [M2+
] (46); HRMS (FD): m/z: calcd for C76H64O8:
1104.4601; found: 1104.4632.
Trimer 3d: M.p. 213.5–214.58C; 1H NMR: d=7.45 (d, J=7.1 Hz, 12H),
7.36 (t, J=7.1 Hz, 12H), 7.28 (d, J=7.1 Hz, 6H), 7.01 (d, J=16.5 Hz,
6H), 6.76 (d, J=16.5 Hz, 6H), 4.22 (q, J=7.1 Hz, 12H), 3.73 (d, J=
15.5 Hz, 12H), 3.53 (d, J=15.5 Hz, 12H) 1.28 ppm (t, J=7.1 Hz, 18H);
13C NMR: d=171.47, 137.78, 137.34, 133.26, 129.15, 128.72, 127.92,
126.51, 125.19, 80.06, 66.59, 62.33, 48.67, 44.38, 14.04 ppm; IR (KBr): n˜ =
2925, 2172, 1736, 1629, 1598, 1448, 1250, 1231, 1186, 1038, 966, 751,
692 cmÀ1; MS (FD): m/z (%): 1660 [M++4] (30), 1659 [M++3] (66), 1658
[M++2] (81), 1657 [M++1] (100), 1656 [M+] (70), 829 [M2++1] (75), 828
[M2+] (56); HRMS (FD): m/z: calcd for C114H96O12: 1656.6902; found:
1656.6921.
Acknowledgements
H.K. acknowledges support from the JSPS KAKENHI (no. 20750024),
the Global COE Program (project no. B01: Catalysis as the Basis for In-
novation in Materials Science), MEXT, and the JST PRESTO project.
We are grateful to Prof. Akihiro Orita (Okayama University of Science)
for the kind suggestions and the use of distannoxane catalyst. We thank
Thienyl macrocycles 2c–4c with ethyl esters: Macrocycles 2c–4c were
prepared from (Z)-1c (17.6 mg, 34 mmol) and CuACTHNURGTNEUNG(OAc)2 (124 mg,
0.68 mmol) in CH3CN (3.4 mL). GPC separation of the crude product
gave dimer 2c (9.2 mg, 53%), trimer 3a (3.7 mg, 21%), tetramer 4a
4522
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ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 4513 – 4524

Acetylene Macrocycles
FULL PAPER
Prof. Tamotsu Inabe (Hokkaido University) for use of the X-ray structur-
al analysis system and Prof. Hajime Ito (Hokkaido University) for the
solid-state fluorescence spectra measurements. MS spectra were meas-
ured by Dr. Eri Fukushi and Mr. Kenji Watanabe at the GC-MS NMR
Laboratory (Faculty of Agriculture, Hokkaido University).
c) T. J. Sisto, M. R. Golder, E. S. Hirst, R. Jasti, J. Am. Chem. Soc.
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