Synthesis of linked symmetrical [3] and [5]rotaxanes having an oligomeric phenylene ethynylene (OPE) core skeleton as a π-conjugated guest via double intramolecular self-inclusion

Article abstract of DOI:10.1016/j.tetlet.2008.12.087

Linked symmetrical [3] and [5]rotaxanes consisting of an oligomeric phenylene ethynylene (OPE) framework as a π-conjugated guest moiety and lipophilic permethylated α-cyclodextrins (PM α-CDs), as macrocyclic hosts have been prepared by double intramolecul

Full text of DOI:10.1016/j.tetlet.2008.12.087

Tetrahedron Letters 50 (2009) 1146–1150
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Tetrahedron Letters
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Synthesis of linked symmetrical [3] and [5]rotaxanes having an oligomeric
phenylene ethynylene (OPE) core skeleton as a
via double intramolecular self-inclusion
p-conjugated guest
a
a
a,
Susumu Tsuda a, Jun Terao b, , Yuji Tanaka , Tomoka Maekawa , Nobuaki Kambe
*
*
a Department of Applied Chemisry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
b Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Linked symmetrical [3] and [5]rotaxanes consisting of an oligomeric phenylene ethynylene (OPE) frame-
Received 24 November 2008
Revised 17 December 2008
Accepted 18 December 2008
Available online 25 December 2008
work as a
rocyclic hosts have been prepared by double intramolecular self-inclusion of an OPE guest unit carrying
two PM -CDs followed by capping with bulky stopper groups using click azide–alkyne Huisgen cycload-
dition or Sonogashira coupling. The structures of these linked rotaxanes were determined by MALDI-TOF
mass spectrum and two-dimensional NMR spectroscopy.
p-conjugated guest moiety and lipophilic permethylated a-cyclodextrins (PM a-CDs), as mac-
a
Ó 2008 Elsevier Ltd. All rights reserved.
Oligomeric phenylene ethynylenes (OPEs) are among the most
extensively studied families of molecular electronics materials
due to their interesting photophysical properties including nonlin-
ear optical (NLO) response,1 luminescence,2,3 and electrolumines-
cence.3 We are interested in developing new methods for
The double intramolecular self-inclusion phenomenon of 3 has
been confirmed by 1H NMR employing different solvents and con-
centrations. The NMR spectrum of aromatic protons of 3 in CD2Cl2
reveals the exclusion of the OPE moiety from the cavity of the PM
a-CDs (Fig. 1a). A spectrum in CD3OD at room temperature showed
encapsulation4 of
p
-conjugated compounds in order to realize
higher solubility, fluorescence quantum yields, electrolumines-
cence efficiencies, and chemical stabilities of the -conjugated sys-
tems. Recently we have reported two new synthetic routes to
linked rotaxanes bearing a -conjugated system as a guest and per-
methylated -cyclodextrin (PM
-CD) as a host (Scheme 1).5,6 Our
strategies employed for the syntheses of these linked rotaxanes
were based on intramolecular self-inclusion of a -conjugated lin-
ear guest unit through lipophilic PM -CD linking to the guest moi-
an equilibrium mixture of two species, 3 and its supramolecular
complex (pseudo linked [3]rotaxane) 30 (Fig. 1b). The intensity of
30 decreased and peaks of 3 increased by warming up to 55 °C
(Fig. 1c). When a more hydrophilic medium (CD3OD–D2O = 3:1)
has been used, 3 was completely converted to the supramolecular
complex 30 at room temperature (Fig. 1d). The evidence that the
NMR spectra of 30 at different concentrations in CD3OD showed
no new peaks ascribable to oligomeric and/or polymeric supramo-
lecular complexes may support double intramolecular self-inclu-
p
p
a
a
p
a
ety to form a pseudo [1]rotaxane which then gave rise to a
[1]rotaxane5 also called linked [2]rotaxane by end-capping (Meth-
od 1) or a linked [3]rotaxane6 by dimerization (Method 2). Herein,
we report the synthesis of OPE-based linked [3] and [5]rotaxanes
via double intramolecular self-inclusion and capping with two
end-groups (Scheme 1, Method 3).
Scheme 2 shows the synthetic route of our OPE-based linked
[3]rotaxane. According to this process, modified PM
a-CD diiodide
1 was prepared by the reaction of 6-O-monotosyl PM
a
-CD with
2,5-diiodo-1,4-benzenediol in 93% yield.7 Sonogashira coupling
reaction of 1 with 1-ethynyl-4-[2-(trimethylsilyl)ethynyl]-ben-
zene, followed by deprotection of the trimethylsilyl group gave
modified OPE having two PM
a-CDs 3 in 75% yield over two
steps.8,9
* Corresponding authors. Tel.: +81 75 383 2516; fax: +81 75 383 2514 (J.T.).
E-mail address: terao@scl.kyoto-u.ac.jp (J. Terao).
Scheme 1. Our synthetic routes to linked rotaxanes.
0040-4039/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2008.12.087

S. Tsuda et al. / Tetrahedron Letters 50 (2009) 1146–1150
1147
PM α-CD
PM α-CD
TMS
Pd(PPh3)2Cl2, CuI
-Pr NH, rt
OH
O
O
monotosyl PM α-CD
I
I
I
I
X
X
K2CO3, DMF, 100 °C
i
2
b
a
c
O
O
HO
PM α-CD
PM α-CD
X = TMS
X =H
2
3
K2CO3, MeOH, rt
1
3
COOH
F
N3
COOH
PM α-CD
D
N
N
O
CuSO4·5H2O
N
N
N
CH3OH/H2O = 1/1
O
E
N
Sodium ascorbate
CH3OH/H2O = 1/1
rt
A
C
O
B
PM α-CD
HOOC
PM α-CD
4a
a'
c'
b'
PM α-CD
O
I
PM α-CD
O
Pd(OAc)2, CuI, Na2CO3
3'
tris(3-sulfonatophenyl)phosphine
hydrate sodium salt
O
PM α-CD
CH3OH/H2O = 1/1
rt
4b
Scheme 2. Synthesis of linked symmetrical [3]rotaxanes 4 via double intramolecular self-inclusion of 3.
tained in 89% yield.10 This evidence suggests that pseudo [1]rotax-
ane 30 was formed efficiently in CH3OH–H2O = 1:1. The structure of
this linked [3]rotaxane 4a was confirmed by MALDI-TOF mass
spectrum, GPC analysis, and by 2D TOCSY, COSY, and ROESY
NMR spectra. The NOEs between protons on the OPE moiety and
the internal protons of the PM
tween HA of the OPE moiety and H6 located on the narrow rim of
the PM -CD indicates that two PM -CDs were located in tail-
to-tail arrangement (Fig. 2).
a-CDs were observed. The NOE be-
a
a
In order to elongate the OPE units, we treated 30 with 2,3,5,6-
tetramethyliodobenzene in CH3OH–H2O = 1:1 in the presence of
Pd(OAc)2, CuI, Na2CO3, and tris(3-sulfonatophenyl)phosphine hy-
drate sodium salt and obtained the desired linked [3]rotaxane hav-
ing four phenylene ethynylene units 4b in pure form but in only a
21% yield, probably because of the insolubility of 2,3,5,6-tetram-
ethyliodobenzene in the mixed solvent of H2O and CH3OH.11 This
problem was solved by using [1]rotaxane 8 as a soluble stopper
Figure 1. The aromatic region of 400 MHz 1H NMR spectra of a two PM
a-CD-linked
OPE 3 in several solvents. (a) CD2Cl2 at rt; (b) CD3OD at rt; (c) CD3OD at 55 °C; (d)
CD3OD–D2O = 3: 1 at rt; (e) CD3OD–D2O = 3: 1 at 55 °C.
sion complex 30. In addition, 30 was stable even at 55 °C in the same
hydrophilic medium (Fig. 1e).
In order to fix pseudo linked [3]rotaxane structure by end-cap-
ping the OPE moiety by click reaction, 30 was treated with 4-azido-
benzoic acid having a bulky group in the presence of CuSO4ꢀ5H2O
and sodium ascorbate at room temperature. After purification by
silica gel column chromatography, the desired linked symmetrical
[3]rotaxane having two phenylene ethynylene units 4a was ob-
Figure 2. ROESY NMR spectrum of linked [3]rotaxane 4a in CD2Cl2 at 25 °C.

1148
S. Tsuda et al. / Tetrahedron Letters 50 (2009) 1146–1150
PM α-CD
SMe
(HO)2B
O
CH3OH/H2O = 1/1
O
Pd(OAc)2, K2CO3
X
SMe
AcHN
I
CH3OH/H2O = 1/1
rt
PM α-CD
PM α-CD
O
AcHN
I
X = NHAc
X =NH2
6
7
8
HClaq, 40 °C
5'
5
NaNO2, KI
H2SO4aq, rt
X = I
8
O
O
Pd(OAc)2, CuI, Na2CO3
MeS
SMe
3'
tris(3-sulfonatophenyl)phosphine
hydrate sodium salt
O
O
PM α-CD
PM α-CD
PM α-CDPM
α-CD
CH3OH/H2O = 1/1
rt
4c
Scheme 3. Synthesis of linked [5]rotaxane 4c via double intramolecular self-inclusion of 3.
COOH
O
N
N
N
N
N
N
O
HOOC
5a
PM α-CD
O
O
PM α-CD
5b
PM α-CD
O
O
MeS
SMe
O
O
PM α-CD
PM α-CD
PM α-CD
5c
Figure 3. The structure of reference compounds 5a–c.
unit in the solvent system. As shown in Scheme 3, 8 was prepared
cation with silica gel column chromatography.13 High solubility of
these PM -CD derivatives 1–8 in various organic solvents is
advantageous for their isolation compared with water soluble CD
derivatives. The structure of 4c was also confirmed by MALDI-
TOF mass, 2D NMR. As shown in Figure 4, OPE guest was highly
via self-inclusion of tolan moiety bearing a PM
a-CD following our
a
method reported previously (Method 1).5,12 The reaction of 30 with
the [1]rotaxane as a stopper unit under Sonogashira coupling reac-
tion conditions gave the desired linked symmetrical [5]rotaxane
having six phenylene ethynylene units 4c in 72% yield after purifi-
insulated with four PM a-CDs according to the space-filling model.

S. Tsuda et al. / Tetrahedron Letters 50 (2009) 1146–1150
1149
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Figure 4. A space-filling model of the linked symmetrical [5]rotaxane.
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Table 1
Wavelengths of the absorption and emission maxima and photoluminescence
quantum yieldsa
Sample
kmax,
(nm) [log
e]
kmax,
(nm)
em
Usolution
Usolid
abs
4a
4b
4c
5a
5b
5c
356 [3.82]
364 [3.75]
372 [4.08]
384 [4.70]b
392 [4.28]
392 [4.66]
390, 411
402, 423
413, 436
423b
444
438, 466
0.82
0.92
0.87
0.82b
0.84
0.91
0.14
0.14
0.37
0.003
0.01
0.19
4. Frampton, M. J.; Anderson, H. L. Angew. Chem., Int. Ed. 2007, 46, 1028–1064.
5. Tsuda, S.; Terao, J.; Kambe, N. Chem. Lett. 2009, 38, 76–77.
6. Tsuda, S.; Terao, J.; Tsurui, K.; Kambe, N., in press.
7. Synthesis of 1: 2,5-dihydroxy-1,4-diiodobenzene (1.20 g, 3.33 mmol), 6-O-
monotosyl PM
a-CD (10.0 g, 7.32 mmol), and dry K2CO3 (9.20 g, 66.6 mmol)
were placed in a round-bottomed flask and dried at 100 °C in vacuo. The
mixture was dissolved in DMF (70 mL). The reaction mixture was stirred at
100 °C overnight. The mixture was diluted with EtOAc and washed with
saturated aqueous NaHCO3 and brine. The organic layer was separated and
dried over Na2SO4. The solvent was removed in vacuo, and the residue was
purified by column chromatography on silica gel with EtOAc–EtOH (9:1) as
eluent to yield 1 as an orange solid (8.43 g, 93%). Mp: 138–141 °C; MALDI-TOF
MS: (m/z) 2767 ([M+Na]+, C112H188I2O60Na, calcd 2770); 1H NMR (400 MHz,
CDCl3, 22.3 °C): dH = 7.20 (s, 2H, ArH), 5.13–5.00 (m, 12H, CD-H1), 4.50–3.10 (m,
174H, CD-H, OCH3); Anal. Calcd for C112H188I2O60ꢀH2O: C, 48.94; H, 6.89. Found:
C, 48.62; H, 6.92.
a
Spectra were recorded in CHCl3. Absolute quantum yields were determined by a
calibrated integrating sphere system.
b
In CHCl3–DMSO = 1:1.
The absorption and emission spectra and photoluminescence
quantum yields of linked rotaxanes 4a–c are summarized in Table
1. The elongation of phenylene ethynylene units from two to six re-
sulted in bathochromic shift by about 16 nm. In order to examine
8. Synthesis of 2: 1 (5.49 g, 2.0 mmol) was dissolved in i-Pr2NH (50 mL). Under a
nitrogen atmosphere, Pd(PPh3)2Cl2 (70 mg, 0.10 mmol), CuI (14 mg,
0.10 mmol) and (4-ethynylphenylethynyl)-silane (1.19 g, 6.0 mmol) were
added into the solution, and then the reaction mixture was stirred at room
temperature. The mixture was filtered through a Celite pad and concentrated,
followed by a chromatographic purification on silica gel with EtOAc–EtOH (9:1)
as eluent to yield 2 as orange solid (4.64 g, 80%). Mp: 138–141 °C; MALDI-TOF
MS: (m/z) 2909 ([M+Na]+, C138H214O60Si2Na, calcd 2910); 1H NMR (400 MHz,
CD2Cl2, 21.4 °C): dH = 7.49 (d, J = 8.4 Hz, 4H, ArH), 7.41 (d, J = 8.4 Hz, 4H, ArH),
7.07 (s, 2H, ArH), 5.08–4.92 (m, 12H, CD-H1), 4.83–2.99 (m, 174H, CD-H, OCH3),
0.23 (s, 18H, (CH3)3Si); Anal. Calcd for C138H214O60Si2ꢀH2O: C, 57.01; H, 7.49.
Found: C, 56.90; H, 7.18.
the shielding effect of PM
a-CD, we compared the fluorescence
quantum yields of 4 with that of the corresponding uninsulated
compounds 5a–c (Fig. 3). The uninsulated compounds 5b–c as ref-
erences were intentionally synthesized by the reaction of 3 with
the corresponding iodobenzene derivatives in i-Pr2NH instead of
1:1 solution of H2O and CH3OH. As expected, there are significant
fluorescence enhancements in 4 especially in solid state suggesting
that encapsulation of OPEs by PM
efficient fluorescence properties.
In conclusion, a highly organic-soluble linked [3] and [5]rotax-
anes were prepared via double intramolecular self-inclusion of
a-CD is essential to attain
9. Synthesis of 3: 2 (644 mg, 0.223 mmol) was dissolved in MeOH (8 mL) and
K2CO3 (1.1 g, 7.96 mmol) was added to the solution. Under
a nitrogen
atmosphere, the reaction mixture was stirred at room temperature for
30 min. The mixture was diluted with EtOAc and washed with brine. The
organic layer was separated and dried over Na2SO4. The solvent was removed
under reduced pressure and the residue was purified by column
chromatography on silica gel with EtOAc–EtOH (9:1) as eluent to yield 3 as a
brilliant yellow solid (573 mg, 94%). Mp: >201 °C (decomposed); MALDI-TOF
MS: (m/z) 2768 ([M+Na]+, C132H198O60Na, calcd 2766); 1H NMR (400 MHz,
CD2Cl2, 14.2 °C): dH = 7.53 (d, J = 8.4 Hz, 4H, ArH), 7.47 (d, J = 8.4 Hz, 4H, ArH),
7.09 (s, 2H, ArH), 5.09–4.93 (m, 12H, CD-H1), 4.86–3.01 (m, 176H, CD-H, CCH,
OCH3); Anal. Calcd for C132H198O60ꢀ2H2O: C, 57.01; H, 7.32. Found: C, 56.62; H,
6.97.
an OPE moiety bearing two PM a-CDs and subsequent end-capping
by click reaction or Sonogashira coupling reaction. These linked
rotaxanes are highly soluble in various organic solvents such as
methanol, ethyl acetate, chloroform, toluene, and DMF. The
remarkable fluorescence enhancement was observed in these
linked rotaxanes both in solution and in solid state. This is the first
successful example of rotaxane synthesis via selective double self-
inclusion process.
10. Synthesis of 4a: 3 (116 mg, 42 lmol) was dissolved in MeOH (12 mL) and water
(12 mL) was added in the solution. This suspended solution was stirred at 70 °C
for 1 h. After cooling to ambient temperature were added 4-azido-benzoic acid
(41 mg, 0.25 mmol), CuSO4ꢀ5H2O (21 mg, 170
lmol), and sodium ascorbate
Acknowledgments
(33 mg, 0.34 mmol) into the solution. The mixture was stirred at room
temperature for 24 h. The reaction mixture was treated with HClaq (0.1 N) and
extracted with CH2Cl2. The combined organic layer was washed with saturated
aqueous NaCl solution and dried over anhydrous Na2SO4. The solvent was
removed under reduced pressure and the residue was purified by column
chromatography on silica gel (9:1, CH2Cl2–MeOH (1% v/v TFA(trifluoroacetic
acid)), 9:1, CH2Cl2–MeOH (5% v/v TFA), MeOH) to yield 4a as a pale yellow solid
(116 mg, 89%). Mp: 247–250 °C; MALDI-TOF MS: (m/z) 3093 ([M+Na]+,
C146H208N6O64Na, calcd 3092); 1H NMR (400 MHz, CD2Cl2, 21.5 °C): dH = 8.35
(s, 2H, ArH), 8.16 (d, J = 8.7 Hz, 4H, ArH), 8.12 (d, J = 8.2 Hz, 4H, ArH), 8.09 (d,
J = 8.2 Hz, 4H, ArH), 7.83 (d, J = 8.7 Hz, 4H, ArH), 7.36 (s, 2H, ArH), 5.01–4.70 (m,
12H, CD-H1), 4.56–2.71 (m, 176H, CD-H, CCH, OCH3); Anal. Calcd for
C146H208N6O64ꢀ3H2O: C, 56.11; H, 6.90; N, 2.69. Found: C, 55.91; H, 6.51; N,
2.66.
The authors thank instrumental Analysis Center, Faculty of
Engineering, Osaka University, for 2D NMR experiments. One of
the authors S.T. express his special thanks for The Global COE (cen-
ter of excellence) Program ‘Global Education and Research Center
for Bio-Environmental Chemistry’ of Osaka University.
References and notes
1. (a) Wautelet, P.; Moroni, M.; Oswald, L.; Moigne, J. L.; Pham, A.; Bigot, J.-Y.
Macromolecules 1996, 29, 446–455; (b) Mcllroy, S. P.; Clo, E.; Nikolajsen, L.;
Frederiksen, P. K.; Nielsen, C. B.; Mikkelsen, K. V.; Gothelf, K. V.; Ogilby, P. R. J.
Org. Chem. 2005, 70, 1134–1146; (c) Zhao, Y.; Shirai, Y.; Slepkov, A. D.; Cheng,
L.; Alemany, L. B.; Sasaki, T.; Hegmann, F. A.; Tour, J. M. Chem. Eur. J. 2005, 11,
3643–3658; (d) Robey, S. W.; Ciszek, J. W.; Tour, J. M. J. Phys. Chem. C 2007, 111,
17206–17212; (e) Mongin, O.; Porrès, L.; Charlot, M.; Katan, C.; Blanchard-
Desce, M. Chem. Eur. J. 2007, 13, 1481–1498.
11. Synthesis of 4b: 3 (100 mg, 36 lmol) was dissolved in MeOH (10 mL) under a
nitrogen atmosphere and degassed water (10 mL) was added to the solution.
This suspended solution was stirred at 70 °C for 1 h. After cooling to ambient
temperature were added 2,3,5,6-tetramethyliodobenzene (24 mg, 91
and Na2CO3 (23 mg, 0.22 mmol) into the solution. Then the catalyst solution of
Pd(OAc)2 (0.33 mg, 1.5 mol), tris(3-sulfonatophenyl)phosphine hydrate
lmol)
l

1150
S. Tsuda et al. / Tetrahedron Letters 50 (2009) 1146–1150
sodium salt (1.7 mg, 2.9
lmol), and CuI (0.035 mg, 0.18
lmol) in
C
74H109NO30SNa, calcd 1547); 1H NMR (400 MHz, CDCl3, 23.6 °C): dH = 8.08
water(0.10 mL), and triethylamine (100
l
L) were added. The mixture was
(d, J = 8.3 Hz, 2H, ArH), 7.65 (d, J = 8.3 Hz, 2H, ArH), 7.36 (d, J = 8.3 Hz, 2H, ArH),
7.28 (d, J = 8.3 Hz, 2H, ArH), 7.23 (d, J = 8.8 Hz, 1H, ArH), 6.44 (m, 2H, ArH),
5.10–4.96 (m, 6H, CD-H1), 4.92–2.86 (m, 89H, NH, CD-H, OCH3), 2.51 (s, 3H,
SCH3); Anal. Calcd for C74H109NO30SꢀH2O: C, 57.61; H, 7.25; N, 0.91. Found: C,
57.54; H, 6.93; N, 0.89. Data for 8: A pale yellow solid (1.9 g, 54% yield); mp:
243–246 °C; MALDI-TOF-MS: (m/z) 1657 ([M+Na]+, C74H107IO30SNa, calcd
1658); 1H NMR (400 MHz, CDCl3, 23.2 °C): dH = 8.14 (d, J = 8.3 Hz, 2H, ArH),
7.68 (d, J = 8.3 Hz, 2H, ArH), 7.53 (d, J = 1.5 Hz, 1H, ArH), 7.49 (dd, J = 1.5, 8.3 Hz,
1H, ArH), 7.36 (d, J = 8.5 Hz, 2H, ArH), 7.29 (d, J = 8.5 Hz, 2H, ArH), 7.25 (d,
J = 8.3 Hz, 1H, ArH), 5.09–4.95 (m, 6H, CD-H1), 4.87–2.90 (m, 87H, CD-H, OCH3),
2.52 (s, 3H, SCH3); Anal. Calcd for C74H107IO30S: C, 54.34; H, 6.59. Found: C,
54.07; H, 6.37.
stirred at room temperature for 24 h. The reaction mixture was treated with
dilute aqueous HCl (0.1 N) and extracted with CH2Cl2. The combined organic
layer was washed with saturated aqueous NaCl solution and dried over
anhydrous Na2SO4, and filtered to remove insoluble fractions. The solvent was
removed under reduced pressure and the residue was purified by column
chromatography on silica gel (9:1, EtOAc–EtOH, 8:2, EtOAc–EtOH) to yield 4b
as a pale yellow solid (23 mg, 21%). Mp: >200 °C (decomposed); MALDI-TOF
MS: (m/z) 3036 ([M+Na]+, C152H222O60Na, calcd 3030); 1H NMR (400 MHz,
CD2Cl2, 21.5 °C): dH = 8.07 (d, J = 8.3 Hz, 4H, ArH), 7.71 (d, J = 8.3 Hz, 4H, ArH),
7.40 (s, 2H, ArH), 6.92 (s, 2H, ArH), 5.05–4.73 (m, 12H, CD-H1), 4.58–2.74 (m,
174H, CD-H, OCH3), 2.30 (s, 12H, ArCH3), 2.20 (s, 12H, ArCH3); Anal. Calcd for
C152H222O60ꢀ3H2O: C, 59.59; H, 7.50. Found: C, 59.51; H, 7.31.
13. Synthesis of 4c: 4c was prepared by the procedure similar to that of 4b. The
residue was purified by column chromatography on silica gel (9:1, EtOAc–
12. Syntheses of 5–8: 5–8 were prepared by the procedures similar to those of a
[1]rotaxane reported previously. Data for 6: A white solid; mp: 242–245 °C;
MALDI-TOF-MS: (m/z) 1587 ([M+Na]+, C76H111NO31SNa, calcd 1589); 1H NMR
(400 MHz, CDCl3, 24.0 °C): dH = 8.12 (d, J = 8.3 Hz, 2H, ArH), 7.67 (d, J = 8.3 Hz,
2H, ArH), 7.44 (m, 2H, ArH), 7.35 (m, 4H, NH, ArH), 7.28 (d, J = 8.3 Hz, 2H, ArH),
5.09–4.96 (m, 6H, CD-H1), 4.91–2.85 (m, 87H, CD-H, OCH3), 2.51 (s, 3H, SCH3),
2.21 (s, 3H, CH3CO); Anal. Calcd for C76H111NO31Sꢀ2H2O: C, 56.95; H, 7.23; N,
0.87. Found: C, 57.13; H, 6.87; N, 0.86. Data for 7: A pale yellow solid (2.76 g,
92% yield); mp: 221–225 °C; MALDI-TOF-MS: (m/z) 1546 ([M+Na]+,
EtOH) to yield 4c as
a pale yellow solid (74 mg, 72%). Mp: >260 °C
(decomposed); MALDI-TOF-MS: (m/z) 5783 ([M+Na]+, C280H410O120S2Na,
calcd 5780); 1H NMR (400 MHz, CD2Cl2, 20.4 °C): dH = 8.10 (d, J = 8.6 Hz, 4H,
ArH), 8.07 (d, J = 8.3 Hz, 4H, ArH), 7.69 (d, J = 8.3 Hz, 4H, ArH), 7.66 (d,
J = 8.6 Hz, 4H, ArH), 7.46 (d, J = 7.8 Hz, 2H, ArH), 7.42 (s, 2H, ArH), 7.37 (d,
J = 8.7 Hz, 4H, ArH), 7.25 (d, J = 8.7 Hz, 4H, ArH), 7.21–7.18 (m, 4H, ArH), 5.05–
4.82 (m, 24H, CD-H1), 4.76–2.70 (m, 348H, CD-H, OCH3), 2.48 (s, 6H, SCH3);
Anal. Calcd for C280H410O120S2ꢀ4H2O: C, 57.66; H, 7.22. Found: C, 57.45; H, 6.84.