Hydrogen bonding-mediated foldamer-bridged zinc porphyrin-C60 dyads: ideal face-to-face orientation and tunable donor-acceptor interacion

Article abstract of DOI:10.1016/j.tet.2009.06.087

Four porphyrin-bridge-C₆₀ dyads have been synthesized by covalently linking the chromophores at the opposite ends of a hydrogen bonded arylamide-derived foldamer bridge. For comparison, four C₆₀-free porphyrin derivatives of the same frameworks have also been prepared. The fully hydrogen bonded bridges enable the appended porphyrin and C₆₀ moieties to contact in a face-to-face manner. ¹H NMR, UV-vis and fluorescent investigations in chloroform indicate that such a structural matching remarkably facilitates the intramolecular energy and electron transfer and charge separation between the two chromophores and also retards the recombination of the charge-separated state. Removing one hydrogen bond considerably reduces the energy and electron transfer. Further removing another one leads to no important interaction between the chromophores to occur.

Full text of DOI:10.1016/j.tet.2009.06.087

Tetrahedron 65 (2009) 7718–7729
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Hydrogen bonding-mediated foldamer-bridged zinc porphyrin-C60 dyads:
ideal face-to-face orientation and tunable donor–acceptor interacion
,
Kui Wang a, Yi-Shi Wu b, Gui-Tao Wang a, Ren-Xiao Wang a, Xi-Kui Jiang a, Hong-Bing Fu b
,
*
,
Zhan-Ting Li a
*
a State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China
b Beijing National Laboratory for Molecular Sciences (BNLMS) and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 May 2009
Received in revised form 15 June 2009
Accepted 19 June 2009
Available online 26 June 2009
Four porphyrin-bridge-C60 dyads have been synthesized by covalently linking the chromophores at the
opposite ends of a hydrogen bonded arylamide-derived foldamer bridge. For comparison, four C60-free
porphyrin derivatives of the same frameworks have also been prepared. The fully hydrogen bonded
bridges enable the appended porphyrin and C60 moieties to contact in a face-to-face manner. 1H NMR,
UV–vis and fluorescent investigations in chloroform indicate that such a structural matching remarkably
facilitates the intramolecular energy and electron transfer and charge separation between the two
chromophores and also retards the recombination of the charge-separated state. Removing one hydro-
gen bond considerably reduces the energy and electron transfer. Further removing another one leads to
no important interaction between the chromophores to occur.
Keywords:
Foldamer
Hydrogen bonding
Porphyrin
Ó 2009 Elsevier Ltd. All rights reserved.
C60
Charge transfer
Fluorescence
UV–Vis absorption
1. Introduction
useful frameworks for controlling the interactions between func-
tional segments.17,19 A number of artificial receptors have been
In the past decades, the development of porphyrin-C60 dyads
have received considerable attention due to their rich redox, optical
and photochemical properties.1 A major consideration in the design
of the porphyrin-C60 dyads is the overall molecular topology,
mainly concerning their distance and spatial orientation,2 which
plays a crucial role in controlling the rate of the photoinduced
electron transfer (PET), the efficiency of charge separation (CS) and
the lifetime of the CS state. Both theory and experiment indicate
that, when structurally possible, the dyads prefer to adopt a face-
to-face conformation to maximize the interaction between the two
chromophores and to favor the through-space donor–acceptor di-
alogues such as efficient and rapid quenching of the porphyrin
fluorescence, generation of the C60 excited state and the charge
transfer state.3–5 However, accurate control of such an orientation
has been a challenge synthetically.6–14
developed to bind ionic or neutral molecules or even protein sur-
faces.20–22 Recently, quinoline-derived foldamers have been used as
rigid linkers to regulate the photoinduced charge transfer between
the two connected oligo(p-phenylene vinylene) and perylene bisi-
mide chromophores.23 We herein describe a new class of arylamide
foldamer-derived zinc porphyrin-C60 dyads. The rigidity of the
linkers enables the appended chromophores to orientate in a face-
to-face manner. As a result, the photophysical process between the
two chromophores can be tuned remarkably by simply controlling
the number of the hydrogen bonds.
2. Results and discussion
2.1. Design and synthesis
In the past decade, there has been a considerable interest in
foldamers, linear molecules that are induced by noncovalent forces
to adopt a specific secondary structure.15–17 Among others,18 hy-
drogen bonded oligoamide foldamers have been established as
Four porphyrin-C60 dyads 1–4 have been synthesized. The de-
sign was based on the recent observation that hydrogen bonded
arylamide oligomers can form stable secondary structures.16c,d,17
Compounds 1 and 2 were expected to form six hydrogen bonds to
drive their arylamide bridge to adopt a rigid crescent conformation
and thus to induce the two appended chromophores to arrange in
a face-to-face manner. CPK modeling showed that keeping the six
hydrogen bonds within the plane of their arylamide backbones
* Corresponding authors. Tel.: þ86 21 54925122; fax: þ86 21 64166128.
E-mail addresses: hongbing.fu@iccas.ac.cn (H.-B. Fu), ztli@mail.sioc.ac.cn (Z.-T. Li).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.06.087

K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
7719
would force the two chromophores to contact closely. Therefore, it
was envisioned that strong donor–acceptor interaction would oc-
cur between them. Compounds 3 and 4 have five and four hydrogen
bonds, respectively. Their flexibility should be increasingly high.
Owing to the inherent conjugation of the arylamide unit, 3 and 4
should mainly have two and four low-energy conformations,
depending on the rotation of the amide relative to the appended
benzene rings (see the structures). Except that one similar to that of
1, their another one and three conformations would lead to long-
distance separation for the porphyrin and C60 moieties. A com-
parison of their photophysical properties with those of 1 would
reveal the influence of the hydrogen bonds. Compounds 5–9 were
prepared as control compounds.
The synthetic route for 1 is shown in Scheme 1. Thus, 13 was
first prepared in 3% yield from the reaction of 10,24 1125 and 12 in
refluxed EtCO2H.26 Hydrolysis of 13 with NaOH in refluxed pyr-
idine afforded 14, which was further treated with SOCl2 in
CH2Cl2 to yield 15. With 15 in hand, 17 was prepared by palla-
dium-catalyzed hydrogenation of 1627 in THF and then coupled
with 1828 in CH2Cl2 in the presence of EDCI to yield 19 in 87%
yield. This ester was further hydrolyzed to 20, which was then
reacted with 2129 in CHCl3 to produce 22 in 76% yield. Further
treatment of 22 with 15 in CH2Cl2 afforded 23 in 83% yield. The
latter underwent the Bingel–Hirsch cyclopropanation in PhMe to
afford 24 in 34% yield.30 Finally, treatment of 24 with zinc
acetate in CH2Cl2 and MeOH afforded 1 in 82% yield. Compounds
2–4 were prepared according to similar routes (Schemes 2–4).
Compounds 5–8 were prepared by treating 23, 29, 35 and 41
with zinc acetate, while 9 was prepared from 19 via the Bingel–
Hirsch cyclopropanation. All the compounds were characterized
using 1H and 13C NMR spectroscopy and (high resolution) mass
spectrometry.
CH3
O
CH3
O
Me
O
Me
O
H
H
H
N
H
H3CO
OCH3
OCH3
N
O
N
N
N
N
Hb
O
O
O
OCH3
OMe
Ha
Hc
O
N
H
O
N
H
O
O
OMe
COX
N
N
N
Ar
Ar
Zn
Zn
N
Ar
Ar
NEt2
NEt2
N
N
N
OMe
CHO
1
2
CO2Me
EtCO2H
Ar
Ar
+
NH
N
N
+
relux, 2 h
3%
N
H
Ar
Ar
t-Bu
t-Bu
Me
Me
O
Me
O
Me
O
CHO
10
O
11
12
HN
H
H
H
N
H
MeO
MeO
N
N
N
Ar
O
O
O
O
SOCl2
NaOH,pyridine
CH2Cl2
reflux, 6 h, 100%
OMe
reflux, 12 h
13: X = OMe
14: X = OH
15: X = Cl
N
N
O
O
H
H
O
N
N
N
N
O
Ar
Ar
Zn
Zn
N
MeO
O2N
OMe
CO2Me
Ar
Ar
MeO
H2N
OMe
COX
OMe
CO2Me
H2, Pd-C, THF
r.t., 12 h, 100%
NEt2
NEt2
N
N
N
3
4
16
17
Ar
Ar
MeO
HN
aq. NaOH
Et2NCOCH2CO2H (18)
Me
O
Me
O
Me
O
Me
O
THF, MeOH
reflux, 2 h, 93%
EDCI, DMAP, CH2Cl2
r.t., 12 h, 87%
19: X = OMe
H
H
H
N
H
O
CH2CONEt2
20: X = OH
MeO
OMe
OMe
N
N
N
N
N
MeO
H2N
OMe
NH2
O
O
O
O
MeO
OMe
H
N
OMe
OMe
OMe
15, NEt3, CH2Cl2
21
HN
O
N
N
O
O
H
H
r.t., 2 h, 83%
O
EDCI, CHCl3, r.t., 12 h
76%
N
N
Zn
N
Zn
N
O
OMe
NH2
O
CH2CONEt2
Ar
Ar
Ar
Ar
22
5
NEt2
6
NEt2
N
N
N
MeO
OMe
MeO HN
O
NH OMe
Ar
Ar
O
Me
O
Me
O
Me
O
Me
O
C60, DBU, CBr4, PhMe
r.t., 3 h, 34%
OMe
H
H
H
N
H
MeO
MeO
O
NH
N
N
N
MeO
MeO HN
OMe
NH
N
N
O
O
O
O
O
Ar
Ar
OMe
NEt2
NH OMe
HN
N
N
O
O
H
H
O
O
O
N
N
Zn
N
N
Zn
O
Ar
23
Ar
OMe
O
Ar
Ar
Ar
7
NEt2
OMe
8
NEt2
HN
O
N
N
N
N
N
N
N
Ar
C60
M
Ar
Ar
Ar
NEt2
N
Et2N
O
H
N
Ar = 3,5-di-tert-butylphenyl
Zn(OAc)2, CH2Cl2
Ar
MeOH, r.t., 12 h, 82%
O
24: M = 2H
1: M = Zn
Ar = 3,5-di-tert-butylphenyl
OMe
O
OMe
9
Scheme 1. The synthetic route for compound 1.

7720
K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
N
COX
MeO
HN
OMe
NH2
21, EDCI
15, NEt3, CH2Cl2
acetone
r.t., 12 h, 76%
r.t., 2 h, 87%
O2N
CO2H
CHO
O
37
38
NH
N
N
11, 12, EtCO2H
Ar
Ar
relux, 3 h, 5%
NO2
N
25
CO2Et
HN
OMe
NH
OMe
NH
MeO
HN
MeO
HN
NaOH, THF/H2O
r. t., 4 h, 95%
Ar
MeO
MeO
SOCl2, CH2Cl2
reflux, 12 h
NO2
26: X = OEt
27: X = OH
28: X = Cl
O
O
O
O
H2
Raney Ni
NH2
MeO
HN
OMe
NH
N
N
NH
N
N
THF, r.t.
4 h, 100%
Ar
Ar
Ar
Ar
NH OMe
HN
HN
N
O
O
22
C60
39
40
NEt3, CH2Cl2
r.t., 2 h, 55%
DBU, CBr4
OMe
Ar
Ar
O
NH
PhMe, r.t., 3 h
30%
OMe
NH
MeO
NH
N
N
O
HN
MeO
Ar
Ar
NEt2
HN
O
O
C60
DBU, CBr4
18
PyBOP, NEt3
MeO
HN
OMe
Ar
29
HN
O
PhMe, r.t.
12 h, 31%
CH2Cl2, r.
t.
12 h, 92%
NH OMe
O
NH
N
N
N
Ar
41
Ar
O
O
NEt2
HN
OMe
O
HN
O
Ar
N
N
N
N
MeO
OMe
NH
Ar
C60
M
Ar
NEt2
OMeHN
Zn(OAc)2, CH2Cl2
MeOH, r.t., 12 h, 100%
O
O
Ar
30: M = 2H
2: M = Zn
Ar = 3,5-di-tert-butylphenyl
HN
O
Scheme 2. The synthetic route for compound 2.
Zn(OAc)2
CH2Cl2/MeOH
r.t., 12 h, 100%
N
N
N
M
N
O
C60
Ar
Ar
42: M = 2H
4: M = Zn
NEt2
Ar = 3,5-di-tert-butylphenyl
Scheme 4. The synthetic route for compound 4.
MeO
18
aq. LiOH
MeO
DCC, NEt3
Ar
THF, MeOH
r.t., 2 h, 76%
HN
CO2Me
CH2CONEt2
CH2Cl2, r.t.
12 h, 63%
H2N
CO2Me
CO2H
O
32
31
MeO
MeO
OMe
OMe
H
21
EDCI, CHCl3
2.2. 1H NMR spectroscopy and hydrogen bonding
N
O
HN
O
HN
O
r.t., 12 h, 64%
CH2CONEt2
OMe
CH2CONEt2
The hydrogen bonding in arylamide derivatives have been well-
established.16c,d,17 Because the porphyin and C60 moieties in com-
pounds 1–4 are not close to the hydrogen bonding units, they
should also form stable hydrogen bonding. The 1H NMR spectra of
1–4 are shown in Figure 1. Actually, the signals of their amide hy-
drogens all appeared in the downfield area (>9.50 ppm for 1 and 2)
in the 1H NMR spectra in CDCl3, indicating that these hydrogens
were indeed engaged in intramolecular hydrogen bonding. The
NOESY spectrum of 1 in CDCl3 exhibited strong NOEs between
the amide hydrogens and the neighboring MeO hydrogens (see the
structures). No similar connections were observed between the
amide hydrogens and the related inner located hydrogens, i.e., H-a-c.
These results also supported that the porphyrin and C60 moieties
did not break the hydrogen bonding of the linker. Considering the
high stability of the five membered N–H/N hydrogen bond in 2,16d
2 should also form a similar folding conformation. 1H NMR spectra
also showed that the two chromophores of 1–4 approached each
other, because comparing to those of their C60-free counterparts 5
and 6 (Fig. 4), the signals of the hydrogens of the pyrroles and the
benzenes at the meso positions of 1 and 2 shifted upfield or
downfield pronouncedly, reflecting the shielding and de-shielding
effects of the C60 moiety. Similar shifting was also exhibited for 3
NH2
34
MeO
OMe
33
MeO HN
O
NH
O
C60
DBU, CBr4
15
NEt3, CH2Cl2
r.t., 2 h, 82%
OMe
O
NH
O
PhMe, r.t., 3 h
44%
NH
N
N
Ar
Ar
NEt2
HN
MeO
MeO HN
OMe
NH
35
Ar
O
O
OMe
O
HN
N
N
N
N
O
Ar
C60
M
Ar
NEt2
Zn(OAc)2, CH2Cl
MeOH, r.t., 12 h, 100%
Ar
Ar = 3,5-di-tert-butylphenyl
36: M = 2H
3: M = Zn
Scheme 3. The synthetic route for compound 3.

K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
7721
a
b
c
d
e
f
g
h
10
9
8
7
PPM
Figure 1. Partial 1H NMR spectrum (300 MHz) of compounds (a) 5, (b) 1, (c) 6, (d) 2, (e)
7, (f) 3, (g) 8, and (h) 4 in CDCl3 (5 mM).
and 4 as compared with 7 and 8 (Fig. 1), suggesting that their C60
was also close to the porphyrin unit, albeit the linkers were in-
creasingly flexible with the decrease of the number of the hydrogen
bonds.
Figure 2. The crystal structures of compounds 44 (upper) and 46 (down), highlighting
the three-center hydrogen bonding of the aryl amide backbones.
2.3. Crystal structures
2.4. Steady-state absorption spectroscopy
To further evaluate the stability of the hydrogen bonding
motif of the malonamide segment, we also prepared 44 and 46
from the reactions of 22 with 43 and 17 with 45, respectively
(Scheme 5). Their crystal structures were obtained and are pro-
vided in Figure 2. It can be found that the molonamide hydro-
gens of both compounds were all engaged in the three-center
hydrogen bonding. As expected, the hydrogen bond of the ter-
minal amide oxygen of 46 was remarkably weaker than the
identical one in 44 due to the steric hindrance between its
diethylamino unit and the neighboring methylene unit. Another
amide of 46 was roughly perpendicular to the cyclopropane
plane, suggesting that, even in the absence of the donor–accep-
tor interaction, the C60 in 1 and 2 should be located toward their
porphyrin unit in a face-to-face manner due to the tendency of
the backbones to form the intramolecular hydrogen bonding.
These results are well consistent with the above 1H NMR in-
vestigations, indicating that the new hydrogen bonded linkers
are efficient in controlling the three dimensional orientation of
the two chromophores.
The absorption spectra of 1–9 in CHCl3 are provided in Figure 3.
The absorption in the visible area was dominated by the porphyrin
bands. The porphyrin moiety of 1 exhibited the typical Soret band
(422 nm) and Q-bands (549 and 587 nm), while the porphyrin of 5
featured maxima at 423, 549 and 587 nm (Fig. 3a). Although,
comparing to that of 5, the Soret band of 1 was blue-shifted only by
1 nm, the molar absorption coefficient was decreased by 44%.
Similar weakening (by 37%) was also observed for 2 as compared to
6. These results clearly indicate that considerable photoinduced
electron transfer occurred between the chromophores.6,8 Because
the porphyrin of 2 was attached to the electron-withdrawing pyr-
idine, the values did not reflect the difference of the structural
matching of 1 and 2. Comparing to that of 7 and 8, which lack the
C60 moiety, the molecular absorption coefficient of the Soret band
of 3 and 4 was reduced by 16% and 2%. The result indicates that the
intramolecular hydrogen bonding played a crucial role in driving
the two chromophores together, while the fully hydrogen bonded
frameworks maximized this through a fully defined conformation.
2.5. Steady-state fluorescence spectroscopy
Me
O
MeO
O
H
The emission spectra of the dyads and their porphyrin coun-
terparts were measured in CHCl3 at the 431 nm excitation wave-
length, at which their molar absorption coefficients were identical
(Fig. 4). Both 1 and 5 displayed fluorescence maxima at 598 and
643 nm, but the porphyrin emission of 1 was remarkably quenched
by the attached C60 by a factor of 4.7. Similar quenching was also
observed for 2–4 (by a factor of 3.3, 0.8 and 0.2) by comparing their
emission with that of the C60-free counterparts 6–8. The quenching
efficiency was quickly reduced with the decrease of the number of
the hydrogen bonds. This is consistent with the above UV–vis re-
sult, showing that the linker of 1 and 2 most efficiently located the
C60 at above the porphyrin moiety to enable rapid quenching of the
N
OMe
H
22
MeO
BOP, NEt3
O
N
CHCl3, r.t.
12 h, 90%
H
O
N
O
N
CO2H
N
43
44
Et2N
Me
O
OMe
17
O
NEt3,CH2Cl2
COCl
H
O
Et2N
N
CO2Me
r.t., 24 h, 34%
Et2N
O
46
45
Scheme 5. The synthetic route for compounds 44 and 46.

7722
K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
1.5
1.2
0.9
0.6
0.3
0.0
(a)
1000
800
600
400
(a)
(2)
x 10
200
0
(1)
550
600
Wavelength (nm)
650
700
750
300
400 500
Wavelength (nm)
600
800
600
400
200
0
0.6
0.4
0.2
0.0
(b)
(b)
(2)
(1)
x 7
550
600
Wavelength (nm)
650
700
700
700
750
750
750
300
400 500
Wavelength (nm)
600
1.2
0.8
0.4
0.0
1000 (c)
800
(c)
600
(2)
(1)
400
x 8
200
0
550
600
650
Wavelength (nm)
300
400
500
Wavelength (nm)
600
(d)
1000 (d)
800
0.6
0.4
0.2
0.0
600
(2)
(1)
400
x 6
200
0
550
600
Wavelength (nm)
650
300
400 500
Wavelength (nm)
600
Figure 4. Fluorescent emission spectra in chloroform at 25ꢂC with excitation at
431 nm: (a) 1 (1) and 5 (2), (b) 2 (1) and 6 (2), (c) 3 (1) and 7, and (d) 4 (1) and 8 (2).
Concentrations were 2.0ꢃ10ꢁ6 M.
Figure 3. UV–vis absorption spectra in chloroform at 25ꢂC: (a) 1 (black), 5 (red) and 9
(green), (b) 2 (black), 6 (red) and 9 (green), (c) 3 (black), 7 (red) and 9 (green), and (d) 4
(black), 8 (red) and 9 (green). The concentration was 2.0ꢃ10ꢁ6 M for all the samples.
porphyrin excited singlet state. For dyads 1–4, no C60 emission was
detected in the range of 700–750 nm,31 suggesting that no impor-
tant singlet–singlet energy transfer from porphyrin to C60 occurred.
Therefore, the quenching should be predominantly caused by the
intramolecular electron transfer from the excited singlet state of
porphyrin (P) to C60 to afford the Pꢀþ/C6ꢀꢁ0 charge-separated radical
ion pair (CSRP).
The quenching efficiency of the porphyrin by the attached C60 in
1 and 2 is lower than that revealed for the cyclophane-based dyads
in which the porphyrin and C60 moieties are held together by two
flexible aliphatic chains.7,9 It is reported that in these dyads the
fluorescence of porphyrin is nearly completely quenched by the
attached C60. In these cyclophanes, the two chromophores ap-
proach each other mainly owing to the simple geometric matching,

K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
7723
together with their inherent donor–acceptor interaction. In the
new foldamer-derived systems, without considering the inherent
donor–acceptor interaction, the low-energy conformation is mainly
controlled by the hydrogen bonds. Any re-orientation of the two
chromophores due to and for the intramolecular energy and/or
electron transfer would require a structural deviation from the
minimum energy conformation controlled by the strong hydrogen
bonding.
2.6. Time-resolved fluorescence studies
Picosecond time-resolved fluorescence experiments were
carried out on 1, 3 and 4 and C60-free 5, 7 and 8 in CHCl3 to
further study the effect of the conformational organization on
the photo-induced electron transfer in the dyads. For compari-
son, all the solutions were excited at 540 nm, and the emission
decay profiles were collected at 597 nm. The results are listed in
Table 1. The time profiles of 1, 3 and 4 can be well-fitted with
a bi-exponential function (Fig. 5). Their lifetimes sf1 and sf2 were
evaluated by the curve-fitting method. The fast-decaying com-
ponent (150 ps for 1, 260 ps for 3 and 280 ps for 4, respectively)
can be assignable to the decay of excited zincporphyrin as a re-
sult of electron transfer from it to C60. The second decay com-
ponent may be produced from Pꢀþ/C6ꢀꢁ0 by direct electron transfer
1
from 1P
*
to C60 or the singlet–singlet energy transfer to give C60
*
followed by electron transfer. Since no evidence was obtained
1
for the formation of C60
*
, it should be reasonable to assign it to
an equilibration between 1P
*
and the CSRP state.32 Both sf1 and
sf2 values are increased from 1 to 3 and to 4, which is consistent
with the above steady-state absorption and fluorescence ob-
servations, again reflecting the effect of the intramolecular hy-
drogen bonding on the structural preorganization. The close
contact favored both decaying processes, leading to the shorter
lifetimes for 1.
The shorter-lived component has large amplitude (0.57) for 1,
small amplitude (0.31) for 3 and average amplitude (0.50) for 4,
which may be rationalized by considering the conformational
complexity of the hydrogen bonded dyads. Removal of a hydrogen
bond would not only increase the flexibility of the skeleton, but also
cause variations on the bond length and angle of the concerned
amide group. Both changes should not be linear with the numbers
of the hydrogen bonds, which may lead to the different amplitude.
The fluorescence decay of 5, 7 and 8 was well-fitted with a single-
exponential decay function. Their lifetimes sf1 are comparable,
which can be assigned to the excited porphyrin. This observation
shows that the C60-free linker has no important impact on the
fluorescence decay. The charge separation (CS) rates from 1P
for 1, 3 and 4 were determined from the following equation by
fr (Table 1). It can be
found that the rate was reduced pronouncedly with the decrease of
the hydrogen bonds on the linker, reflecting the increase of the
structural flexibility from 1 to 3 and then to 4. The related quantum
*
to C60
Figure 5. Time profiles of the fluorescence of (a) 1 (purple) and 5 (blue), (b) 3 (purple)
and 7 (blue), and (c) 4 (purple) and 8 (blue) in chloroform at 597 nm upon excitation at
540 nm. Concentrations were 2.0ꢃ10ꢁ5 M and the red was pump pulse.
using the fluorescence lifetimes: kcs¼1/sf1ꢁ1/
s
(Table 1). The FCS is high for all the three dyads, implying that their
C60 moiety is still close to the porphyrin moiety for the charge
separation process to occur, while the highest FCS exhibited by 1
supports that this dyad possesses the most matched relative ori-
entation between the two chromophores.
yields (FCS) were obtained from the equation: FCS¼1ꢁ(sf1
/sfr)
Table 1
a,b
The PET procedure parameters of 1, 3, 4, 5, 7, and 8 in CHCl3
Comp
sf1 (ps)
sf2 (ps)
sfr (ps)
kCS (sꢁ1
)
FCS
2.7. Time-resolved absorption studies
1
5
3
7
4
8
150 (0.57)
610 (0.43)
6.1ꢃ109
3.2ꢃ109
2.9ꢃ109
0.92
1790
1440
1570
To shed more light on the ET process, time-resolved transient
spectra of 1, 3 and 4 in CHCl3 were measured by femtosecond laser
photolysis with excitation wavelength at 400 nm for selective
photoexcitation of zincporphyrin. Global analysis was employed on
twenty kinetic traces within the spectral range of 970–1160 nm,
leading to two decay components, as shown in Figure 6. The decay
260 (0.31)
280 (0.50)
980 (0.69)
1310 (0.50)
0.82
0.82
a
lexc¼540 nm, lobs¼597 nm, concentrations were 2.0ꢃ10ꢁ5 M for all the samples.
b
Values in parentheses are relative amplitudes.

7724
K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
3. Conclusions
0.0020
0.0016
0.0012
0.0008
0.0004
0.0000
We have demonstrated that the hydrogen bonded arylamide
foldamer is a useful linker to control the relative orientation and
consequently the energy and electron transfer of the porphyrin and
C60 moieties. Considering that many donor–acceptor systems have
been established, the porphyrin and C60 moieties in the present
dyads can be readily replaced with other electron donors or ac-
ceptors. The shape of the frameworks can also be readily regulated
by simply changing the position of the substituents for the hydro-
gen bonding. Therefore, this approach may be developed as a gen-
eral strategy to tune the photophysical properties of dyads or even
triads. Since the charge recombination rate of 1 is retarded in the
fully hydrogen bonded architecture, we may expect longer lifetime
of charge separation if another C60 or porphyrin moiety is in-
troduced to form a similar triad or more complexed systems.
Therefore, the work opens many possibilities for the development
of new functional molecules and materials.
0.72 ps
1.25 ns
950
1000
1050
wavelength (nm)
1100
1150
0.0020
0.0016
0.0012
0.0008
0.0004
0.0000
4. Experimental section
4.1. General methods
1.20 ps
1.00 ns
See Ref. 20b.
4.2. Time-resolved fluorescence experiments
The measurements were carried out on the ps time-resolved
fluorescence spectrometer. The 540-nm laser pulses were gener-
ated from a Ti:sapphire regenerative amplifier and used as the
excitation pulses. The pulse energy was about 100 nJ/pulse at the
sample. Fluorescence gathered with the 90-degree-geometry was
dispersed by a polychromator and collected with a photon-count-
ing type streak camera. The data detected by digital camera is
rountinely transferred to PC for analysis with HPDTA software. The
spectral resolution was 0.2 nm and the temporal resolution was
2–100 ps depending on the delay-time-range setting.
1000
1050
wavelength (nm)
1100
1150
950
0.0020
0.0016
0.0012
0.0008
0.0004
0.0000
1.0 ps
0.96 ns
4.3. Time-resolved absorption experiments
The 800-nm laser pulses generated from a Ti:sapphire re-
generative amplifier were frequency doubled and used as the pump
pulses. The residual 800-nm pulses were further attenuated and
focusedinto a 3-mm sapphire plate to generatethe probe pulses. The
time delay between the pump and probe beams were regulated
through a computer-controlled motorized translation stage in the
probe beam. A magic-angle scheme was adopted in the pump-probe
measurement. The temporal resolution between the pump and the
probe pulses was determined to be w150 fs (FWHM). The trans-
mitted light was detected by an InGaAs linear image sensor. The
1150
1000
1050
wavelength (nm)
1100
950
Figure 6. Decay associated spectra obtained from global analysis on several repre-
sentive kinetic traces within the range of 970–1150 nm recorded on the 1600 ps time
scale.
excitation pulsed energy was 0.2
mJ/pulse as measured at the rotat-
ing sample cell (optical path length 1 mm). A typical absorbance of
0.4–0.8 at the excitation wavelength was used. The stability of the
solutions was spectrophotometrically checked before and after each
experiment. Analysis of the kinetic traces derived from time-re-
solved spectra was performed individually and globally using non-
linear least-square fitting to a general sum-of-exponentials function
after deconvolution of instrument response function (IRF). Decay-
associated spectra (DAS) were acquired from global analysis of some
representative kinetic traces at selected wavelengths. All the spec-
troscopic measurements were carried out at room temperature.
associated spectra (DAS) of the short components share a similar
feature, assignable to the excited zincporphyrin. All the DAS of the
three dyads exhibited broad absorption band centered about
1040 nm, which is characteristic of the C60 radical anion. Therefore,
the charge recombination process can be evaluated with time
constants of 8.0ꢃ108 (for 1),1.0ꢃ109 (for 3) and 1.1ꢃ109 (for 4) sꢁ1. It
can be found that the values are decreased notably, indicating that
the charge-recombination rate becomes quicker when the rigidity
of the arylamide framework is reduced. This study, together with
the above transient fluorescence studies, reveals that the fully hy-
drogen bonded dyad 1 not only favors the charge transfer, but also
retards the charge recombination, impling that the charge re-
combination in 1 has been pushed into the Marcus inverted
region.33
4.4. Compound 13
To a solution of 10 (10.6 g, 55.0 mmol) and 11 (36.0 g, 0.17 mol)
in refluxed EtCO2H (500 mL) was added pyrrole 12 (15.3 mL,

K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
7725
0.22 mol) in 0.5 h. The solution was refluxed for 2 h and then
concentrated. The resulting residue was dissolved in toluene
(200 mL) and the solution concentrated again. This process was
repeated for three times and the resulting slurry subjected to col-
umn chromatography (CH2Cl2/n-hexane 1:1) to give 13 as a purple
40.7,14.4,12.9. MS (EI): m/z 352 [M]þ. Anal. Calcd for C17H24N2O6: C,
57.94; H, 6.68; N, 7.95. Found: C, 57.69; H, 6.98; N, 7.49.
4.9. Compound 41
solid (1.88 g, 3%). 1H NMR (300 MHz, CDCl3):
d
9.08 (d, J¼2.4 Hz,1H),
1H NMR (300 MHz, CDCl3):
d 10.55 (s, 1H), 10.43 (s, 1H), 9.44 (s,
8.91 (s, 6H), 8.83 (d, J¼4.8 Hz, 2H), 8.68 (d, J¼2.4 Hz, 1H), 8.32 (dd,
J1¼8.1 Hz, J2¼2.1 Hz, 6H), 8.10–8.06 (m, 6H), 7.80–7.76 (m, 3H), 7.38
(d, J¼8.7 Hz,1H), 4.21 (s, 3H), 3.91 (s, 3H),1.52 (s, 64H), ꢁ2.73 (s, 2H).
MS (MALDI-TOF): m/z 1040 [MþH]þ. Anal. Calcd for C71H82N4O3: C,
82.04; H, 7.95; N, 4.62. Found: C, 82.05; H, 8.08; N, 5.15.
1H), 9.27 (s, 1H), 8.91–8.87 (m, 8H), 8.30 (d, J¼8.4 Hz, 1H), 8.20 (s,
1H), 8.14–8.10 (m, 6H), 7.82 (s, 4H), 7.63 (d, J¼7.8 Hz, 1H), 7.42 (t,
J¼8.7 Hz, 2H), 6.65 (s,1H), 4.36 (s, 3H), 4.07 (s, 3H), 3.96 (s, 3H), 3.44
(s, 2H), 3.42–3.33 (m, 4H), 1.56 (s, 54H), 1.24–1.09 (m, 6H), ꢁ2.66 (s,
2H). 13C NMR (100 MHz, CDCl3):
d 167.6, 164.8, 164.5, 162.5, 157.1,
148.8,148.7,148.6,148.6,146.3, 141.4,141.3,138.3, 136.1,135.7,130.0,
129.8, 129.7, 129.6, 129.2, 122.9, 122.8, 121.5, 121.4, 121.0, 120.8,
120.4, 118.5, 118.3, 115.5,110.0, 95.6, 56.6, 56.4, 56.2, 42.6, 40.9, 39.9,
35.0, 32.3, 31.8, 31.5, 31.3 (d), 14.2, 12.8, 1.1. MS (MALDI-TOF): m/z
1437.0 [MþH]þ. HRMS (MALDI-FT): Calcd for C92H107N8O7 [MþH]þ:
1435.8246. Found: 1435.8257.
4.5. Compound 26
1H NMR (300 MHz, CDCl3):
d
9.18 (d, J¼4.6 Hz, 1H), 9.02 (s, 1H),
8.93 (d, J¼8.8 Hz, 6H), 8.72 (d, J¼4.7 Hz, 2H), 8.35 (d, J¼4.8 Hz, 1H),
8.08 (s, 6H), 7.81 (d, J¼1.2 Hz, 3H), 4.59 (q, J¼7.1 Hz, 2H), 1.55–1.51
(m, 57H), ꢁ2.70 (s, 2H). 13C NMR (100 MHz, CDCl3):
d 165.6, 152.3,
4.10. Compound 20
148.9, 148.8, 148.3, 146.9, 141.1, 141.0, 132.0, 130.2, 129.8, 129.7,
122.6, 122.0, 121.2, 114.6, 62.2, 35.1, 31.8, 31.5, 14.4. MS (MALDI-
TOF): m/z 1024.8 [MþH]þ. HRMS (MALDI-FT): Calcd for C70H82N5O2
[MþH]þ: 1024.6472. Found: 1024.6463.
A solution of 19 (0.50 g, 1.42 mmol) and lithium hydroxide
monohydrate (1.60 g, 15.2 mmol) in MeOH (200 mL) was stirred for
2 h and then concentrated with a rotavapor. The resulting slurry
was added to water (10 mL). The mixture was acidified with diluted
HCl to pH¼2 and then extracted with CHCl3 (20 mLꢃ3). The organic
phases were combined and washed with water (30 mL) and brine
(30 mL), and dried over sodium sulfate. Removal of the solvent
afforded 20 as a white solid (0.48 g, 100%). 1H NMR (300 MHz,
4.6. Compound 14
A
solution of 13 (0.10 g, 0.10 mmol) and NaOH (20 mg,
0.50 mmol) in pyridine (20 mL) and water (4 mL) was heated under
reflux for 6 h and then concentrated with a rotavapor. The resulting
slurry was treated with diluted HCl (0.5 mL) to pH¼3 and then the
mixture extracted with CH2Cl2 (10 mL). The organic phase was
washed with water (10 mL) and brine (10 mL), and dried over so-
dium sulfate. Removal of the solvent under reduced pressure
afforded 14 as a purple solid (0.10 g, 100%). 1H NMR (300 MHz,
CDCl3):
3H), 3.49–3.47 (m, 6H), 1.24 (t, J¼7.5 Hz, 1H), 1.18 (t, J¼7.5 Hz, 1H).
MS (ESI): m/z 338 [M]þ. 13C NMR (100 MHz, CDCl3):
167.7, 164.9,
d 10.21 (s, 1H), 8.96 (s, 1H), 6.54 (s, 1H), 4.08 (s, 3H), 4.01 (s,
d
164.2, 155.8, 154.5, 125.5, 122.2, 109.7, 94.9, 57.0, 56.4, 42.8, 40.9,
40.5, 14.4, 12.9. Anal. Calcd for C16H22N2O6: C, 56.80; H, 6.55; N,
8.28. Found: C, 56.58; H, 6.69; N, 8.01.
CDCl3):
d
8.91 (s, 6H), 8.83 (d, J¼4.8 Hz, 2H), 8.92–8.88 (m, 6H), 8.76
(d, J¼4.8 Hz, 2H), 8.43 (dd, J1¼8.6 Hz, J2¼2.7 Hz, 1H), 8.10–8.07 (m,
4.11. Compound 22
6H), 7.82–7.78 (m, 3H), 7.47 (d, J¼8.7 Hz, 1H), 4.38 (s, 3H), 1.53 (s,
54H), ꢁ2.73 (s, 2H). 13C NMR (100 MHz, CDCl3):
d 165.8, 157.8, 149.0,
A solution of 20 (0.32 g, 1.92 mmol), 21 (0.16 g, 0.48 mmol), EDCI
(0.14 g, 0.72 mmol) and DMAP (80 mg) in CHCl3 (100 mL) was
stirred for 12 h and then washed with saturated aqueous NaHCO3
(50 mL), water (50 mLꢃ3) and brine (50 mL), and dried over so-
dium sulfate. The solvent was removed and the resulting residue
subjected to column chromatography (CH2Cl2/MeOH, 50:1) to give
22 as a pale brown solid (0.14 g, 76%). 1H NMR (300 MHz, CDCl3):
148.8,141.3,141.2, 140.0, 138.5,136.6, 130.0, 129.8, 129.7,121.9,121.7,
121.1, 117.0, 116.2, 110.1, 56.9, 35.1, 31.8. MS (MALDI-TOF): m/z 1026
[MþH]þ. Anal. Calcd for C70H80N4O3: C, 81.99; H, 7.86; N, 5.46.
Found: C, 81.47; H, 7.98; N, 5.08.
4.7. Compound 27
d
10.24 (s, 1H), 9.99 (s, 1H), 8.98 (s, 1H), 8.17 (s, 1H), 6.51 (s, 1H), 6.51
1H NMR (300 MHz, CDCl3):
d
9.18 (d, J¼5.1 Hz, 1H), 9.03 (s, 1H),
(s, 1H), 4.04 (s, 3H), 3.97 (s, 3H), 3.88 (s, 3H), 3.84 (s, 3H), 3.48 (s,
8.96–8.93 (m, 6H), 8.74–8.72 (m, 2H), 8.36 (d, J¼4.5 Hz, 1H), 8.09 (s,
2H), 3.44–3.40 (m, 4H), 1.22 (t, J¼6.9 Hz, 3H), 1.17 (t, J¼7.2 Hz, 3H).
6H), 7.82 (s, 3H), 1.54 (s, 54H), ꢁ2.70 (s, 2H). 13C NMR (100 MHz,
MS (ESI): m/z 489 [MþH]þ. 13C NMR (100 MHz, CDCl3):
d 167.9,
CDCl3):
d 159.6, 148.9, 148.8, 141.1, 141.0, 129.9, 129.7, 122.8, 122.2,
164.0,162.1, 154.8, 153.1,142.8,141.4, 129.9, 125.0, 122.9, 121.4,114.9,
108.6, 97.7, 95.2, 77.2, 57.3, 56.5, 56.2, 42.9, 40.9, 14.4, 13.0. MS-HR
(MALDI-TOF-FT): Calcd for C24H32N4O7Na [MþNa]þ: 511.2173.
Found: 511.2163.
121.2, 35.1, 32.1, 31.8, 31.5, 31.4, 30.4, 29.7. MS (MALDI-TOF): m/z
996.9 [MþH]þ. HRMS (MALDI-FT): Calcd for C68H78N5O2 [MþH]þ:
996.6125. Found: 996.6150.
4.8. Compound 19
4.12. Compound 23
A solution of 17 (1.59 g, 7.55 mmol), 18 (1.26 g, 7.93 mmol), EDCI
(3.69 g, 8.31 mmol) and DMAP (50 mg, 0.4 mmol) in CH2Cl2 (50 mL)
and NEt3 (3.46 mL, 24.9 mmol) was stirred for 12 h and then
washed with diluted aqueous HCl (0.5 N, 25 mL), water (2ꢃ25 mL)
and brine (25 mL), and dried over sodium sulfate. Upon removal of
the solvent with a rotavapor, the crude product was recrystallized
from MeOH to give 19 as a white solid (2.31 g, 87%). 1H NMR
A solution of 14 (0.16 g, 0.15 mmol) and thionyl chloride
(0.72 mL, 9.90 mmol) in CH2Cl2 (30 mL) was heated under reflux for
12 h and then concentrated under reduced pressure to afford 15 as
dark green solid. The solid was dissolved in CH2Cl2 (30 mL) and the
solution added to a stirred solution of 22 (78 mg, 0.15 mmol) and
NEt3 (0.06 mL, 0.51 mmol) in CH2Cl2 (30 mL). The solution was
stirred for 2 h and then washed with diluted HCl (0.1 N, 30 mL),
water (30 mLꢃ2) and brine (30 mL), and dried over sodium sulfate.
After the solvent was removed with a rotavapor, the resulting crude
prude was subjected to flash chromatography (CH2Cl2/MeOH, 50:1)
to give 5 as a purple solid (0.19 g, 83%). 1H NMR (300 MHz, CDCl3):
(300 MHz, CDCl3):
d 10.15 (s, 1H), 8.79 (s, 1H), 6.50 (s, 1H), 3.98 (s,
3H), 3.92 (s, 3H), 3.85 (s, 3H), 3.47–3.36 (m, 6H), 1.24 (t, J¼6.9 Hz,
3H), 1.17 (t, J¼6.9 Hz, 3H). 13C NMR (100 MHz, CDCl3):
d 167.7, 165.7,
164.1, 157.5, 153.4, 124.0,120.5, 111.4, 95.8, 56.5, 56.1, 51.7, 42.8, 40.9,

7726
K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
d
10.43 (s, 1H), 10.04 (s, 1H), 9.68 (s, 1H), 9.49 (s, 1H), 9.28 (d,
8.87 (m, 8H), 8.60 (s, 1H), 8.27 (d, J¼7.8 Hz, 1H), 8.17–8.05 (m, 6H),
7.78 (s, 3H), 7.37 (d, J¼8.1 Hz, 1H), 6.46 (s, 1H), 6.20 (s, 1H), 4.29 (s,
3H), 3.97 (s, 3H), 3.84 (s, 6H), 3.61 (s, H), 4.29–3.61 (m, 4H), 1.50 (s,
J¼2.4 Hz, 1H), 8.91–8.85 (m, 9H), 8.27 (dd, J1¼8.1 Hz, J2¼2.4 Hz, 1H),
8.12–8.07 (m, 6H), 7.79–7.78 (m, 3H), 7.39 (d, J¼8.4 Hz, 1H), 6.55 (s,
1H), 6.41 (s, 1H), 4.31 (s, 3H), 3.99 (s, 3H), 3.96 (s, 3H), 3.89 (s, 3H),
3.87 (s, 3H), 3.39–3.27 (m, 6H), 1.55 (s, 54H), 1.12 (t, J¼7.2 Hz, 3H),
1.08 (t, J¼7.2 Hz, 3H), ꢁ2.70 (s, 1H). 13C NMR (100 MHz, CDCl3):
54H), 1.23 (t, J¼6.6 Hz, 3H), 1.14 (t, J¼6.6 Hz, 3H), ꢁ2.66 (s, 1H). 13
C
NMR (100 MHz, CDCl3):
d 157.1, 148.8, 148.6, 145.0, 144.1, 144.0,
143.5, 143.2, 143.0, 142.3, 141.9, 141.8, 141.7, 141.5, 141.1, 140.5, 138.4,
130.1, 129.8 (d), 129.6, 121.5, 121.1, 120.9, 110.0, 77.2, 73.6, 56.5, 56.4,
55.9, 42.7, 40.2, 35.1, 31.9, 31.8, 29.7, 13.9, 12.7, 1.0. MS (MALDI-TOF):
m/z 2216.8 [MþH]þ. HRMS (MALDI-FT): Calcd for C154H109N8O9
[MþH]þ: 2212.8396. Found: 2213.8312.
d
168.0, 164.0, 162.7, 162.2, 157.3, 153.4, 149.0, 148.9, 148.8 (d), 146.2,
146.1, 141.6, 141.5, 139.0, 135.9, 130.2, 130.0, 129.9, 129.8, 125.8,
122.0, 121.6, 121.5, 121.3, 121.1, 121.1, 121.0, 118.7, 115.7, 114.8, 110.1,
95.9, 95.2, 77.5, 56.8, 56.6 (d), 56.2, 43.0, 41.2, 41.0, 35.2, 35.2, 32.0,
14.5, 13.1. MS (MALDI-TOF): m/z 1497 [MþH]þ. HRMS (MALDI-FT):
Calcd for C94H111N8O9 [MþH]þ: 1495.8452. Found: 1495.8468.
4.17. Compound 30
1H NMR (300 MHz, CDCl3):
d
10.38 (d, J¼2.7 Hz, 1H), 9.97 (s, 1H),
4.13. Compound 29
9.55 (s, 1H), 9.09 (s, 1H), 8.94 (d, J¼4.8 Hz, 1H), 8.90–8.84 (m, 6H),
8.74–8.73 (m, 2H), 8.29 (d, J¼5.7 Hz, 1H), 8.13–8.11 (m, 3H), 8.00–
7.96 (m, 4H), 7.75–7.73 (m, 3H), 6.46 (s,1H), 6.09 (s,1H), 3.97 (s, 3H),
3.85 (s, 3H), 3.74 (s, 3H), 3.47 (s, 3H), 1.47 (s, 54H), 1.18–1.07 (m, 6H),
1H NMR (300 MHz, CDCl3):
d 10.55 (s, 1H), 10.09 (s, 1H), 9.73 (s,
1H), 9.64 (s, 1H), 9.26 (s, 1H), 9.02 (d, J¼4.8 Hz, 1H), 8.94–8.92 (m,
6H), 8.80–8.77 (m, 2H), 8.29 (dd, J1¼4.7 Hz, J2¼0.75 Hz, 1H), 8.10–
8.08 (m, 6H), 8.01 (s,1H), 7.80–7.79 (m, 3H), 6.64 (s,1H), 6.47 (s,1H),
4.06 (s, 3H), 4.02 (s, 3H), 3.95 (s, 1H), 3.92 (s, 3H), 3.42–3.33 (m, 6H),
ꢁ2.77 (s, 2H). 13C NMR (100 MHz, CDCl3):
d 162.4, 161.2, 152.4,
148.8, 145.1, 144.2, 144.0, 143.8, 143.3, 143.0, 142.9, 142.3, 142.0,
141.8, 141.7, 141.3, 141.2, 140.3, 138.2, 131.8, 129.8, 129.7, 122.0, 121.8,
121.1, 115.6, 77.3, 56.3, 56.2, 56.0, 55.9, 42.7, 40.3, 35.1, 31.8, 31.8,
31.5, 31.4, 29.7, 29.6, 29.4, 22.7, 14.1, 13.9, 12.8, 1.03. MS (MALDI-
TOF): m/z 2186.0 [MþH]þ. HRMS (MALDI-FT): Calcd for
C152H106N9O8 [MþH]þ: 2184.8163. Found: 2184.8159.
1.53 (s, 54H), 1.18–1.09 (m, 6H). 13C NMR (100 MHz, CDCl3):
d 167.9,
163.8, 162.1, 161.7, 154.9, 153.2, 152.5, 149.3, 148.9, 148.7, 146.4,
146.2, 141.3, 141.1, 131.7, 130.0, 129.8, 129.7, 127.8, 125.8, 122.3, 122.0,
121.9, 121.2, 120.5, 115.4,115.1, 115.0, 95.9, 95.2, 56.6, 56.5, 56.1, 42.8,
41.0, 40.8, 35.1, 31.9, 31.8, 29.7, 14.3, 12.9. MS (MALDI-TOF): m/z
1467.9 [MþH]þ. HRMS (MALDI-FT): Calcd for C92H108N9O8 [MþH]þ:
1466.8298. Found: 1466.8315.
4.18. Compound 36
4.14. Compound 35
1H NMR (300 MHz, CDCl3):
d 10.46 (s, 1H), 9.26 (s, 1H), 9.15 (d,
J¼2.1 Hz, 1H), 9.01 (s, 1H), 8.81–8.73 (m, 9H), 8.15 (dd, J1¼8.3 Hz,
J2¼1.8 Hz,1H), 8.03–8.01 (m, 7H), 7.68–7.65 (m, 4H), 7.28 (d, J¼8.7 Hz,
1H), 6.82 (d, J¼9.3 Hz,1H), 6.46 (s,1H), 4.17 (s, 3H), 3.88 (s, 3H), 3.76 (s,
3H), 3.75 (s, 3H), 4.17–3.75 (m, 2H), 3.44 (s, 2H), 1.42 (s, 54H), 1.15 (t,
J¼7.5 Hz, 3H),1.05 (t, J¼7.5 Hz, 3H), ꢁ2.76 (s, 2H). 13C NMR (100 MHz,
1H NMR (300 MHz, CDCl3):
d 10.55 (s, H),10.34 (s,1H), 9.49 (s,1H),
9.31 (s, 1H), 8.95–8.90 (m, 8H), 8.31 (d, J¼8.1 Hz, 1H), 8.22 (s, 1H),
8.15–8.12 (m, 6H), 7.83 (s, 3H), 7.76 (d, J¼8.1 Hz,1H), 7.40 (d, J¼8.7 Hz,
1H), 6.92 (d, J¼8.7 Hz, 1H), 6.64 (s,1H), 4.33 (s, 3H), 4.04 (s, 3H), 3.95
(s, 3H), 3.94 (s, 3H), 3.49 (s, 2H), 3.46–3.32 (m, 4H),1.57 (s, 54H),1.20
(t, J¼6.9 Hz, 3H), 1.14 (t, J¼6.9 Hz, 3H), ꢁ2.64 (s, 2H). 13C NMR
CDCl3): d 164.3, 162.4, 159.8, 157.1, 148.8, 148.6, 143.8, 143.7 (d), 143.6,
143.4, 143.1, 143.0, 142.5, 141.9, 141.7, 141.5, 141.4 (d), 140.7, 140.3,
138.2,129.9,129.8,121.5,120.9,118.6,110.3,110.1, 95.6, 77.2, 57.9, 56.6,
56.5, 56.3, 56.1, 42.8, 40.4, 35.0, 31.8, 31.6, 29.7, 22.7,14.1,13.8,12.6,1.0.
MS (MALDI-TOF): m/z 2186.2 [MþH]þ. HRMS (MALDI-FT): Calcd for
C153H107N8O8 [MþH]þ: 2183.8216. Found: 2183.8206.
(100 MHz, CDCl3): d 167.5,164.6,164.4,162.5,157.1,151.1,148.8,148.6,
148.6,146.2 (d),141.5,141.4,138.0,135.7,130.0,129.8 (d),129.6,127.8,
127.3, 124.7, 121.6, 121.4 (d), 120.9 (d), 118.6, 117.9, 115.6, 110.0, 95.8,
56.7, 56.5, 56.4, 56.1, 42.8, 40.9, 40.9, 35.1 (d), 31.8,17.6,14.4,12.9,1.0.
MS (MALDI-TOF): m/z 1467.2 [MþH]þ. MS-HR (MALDI-FT): Calcd for
C93H109N8O8 [MþH]þ: 1465.8389. Found: 1465.8363.
4.19. Compound 42
4.15. Compound 39
1H NMR (300 MHz, CDCl3):
d 10.46 (s, 1H), 10.40 (s, 1H), 9.23 (d,
1H NMR (300 MHz, CDCl3):
d 10.60 (s, 1H), 9.53 (s, 1H), 9.30 (d,
J¼1.2 Hz, 1H), 9.05 (s, 1H), 8.92–8.77 (m, 8H), 8.41 (d, J¼8.7 Hz, 1H),
8.21–7.79 (m, 13H), 7.51 (d, J¼8.1 Hz, 1H), 7.41 (d, J¼8.1 Hz, 1H), 6.53
(s, 1H), 4.32 (s, 3H), 4.00 (s, 3H), 3.83 (s, 3H), 3.76–3.31 (m, 4H), 1.04
(t, J¼7.2 Hz, 3H), 0.89 (t, J¼7.2 Hz, 3H), ꢁ2.66 (s, 2H). 13C NMR
J¼2.4 Hz, 1H), 8.95–8.89 (m, 8H), 8.67 (s, 1H), 8.33 (dd, J1¼8.3 Hz,
J2¼2.4 Hz, 1H), 8.29–8.26 (m, 2H), 8.20 (d, J¼8.1 Hz, 1H), 8.15–8.11
(m, 6H), 7.83 (s, 3H), 7.59 (t, J¼8.1 Hz, 1H), 7.42 (d, J¼8.7 Hz, 1H),
6.60 (s, 1H), 4.33 (s, 3H), 4.03 (s, 3H), 3.92 (s, 3H), 1.57 (s, 54H),
(100 MHz, CDCl3): d 148.8, 148.7, 148.6 (d), 144.1, 143.7, 143.5, 143.3,
ꢁ2.65 (s, 2H). 13C NMR (100 MHz, CDCl3):
d 160.6, 157.1, 148.9, 148.7,
142.7, 142.6, 141.5 (d), 140.1, 139.9, 137.5, 135.8, 130.0, 129.8, 129.6,
129.5, 121.6, 121.5, 120.9, 56.6, 56.5, 56.2, 33.8, 31.9, 31.8, 30.4, 30.2,
29.7, 29.5, 29.4, 26.7, 22.7, 14.2, 14.1, 13.7, 12.7, 1.0. MS (MALDI-TOF):
m/z 2155.4 [MþH]þ. HRMS (MALDI-FT): Calcd for C152H105N8O7
[MþH]þ: 2153.8132. Found: 2153.8101.
148.6, 148.2, 146.5, 141.4 (d), 138.6, 138.1, 136.9, 135.9, 133.3, 130.0,
129.8 (d), 129.6, 125.8, 121.9, 121.7, 121.4, 121.0, 120.7, 119.7, 118.4,
115.4, 110.1, 95.4, 77.2, 56.6, 56.5, 56.2, 35.1, 31.8, 31.4, 1.0. MS
(MALDI-TOF): m/z 1325.3 [MþH]þ. MS-HR (MALDI-TOF-FT): Calcd
for C85H94N7O7 [MþH]þ: 1324.7214. Found: 1324.7209.
4.20. Compound 44
4.16. Compound 24
1H NMR (300 MHz, CDCl3):
d 10.18 (s, 1H), 10.10 (s, 1H), 9.81 (s,
To a stirred solution of 23 (0.15 g, 0.10 mmol), C60 (72 mg,
0.10 mmol), CBr4 (33 mg, 0.10 mmol) in toluene (200 mL) was
added DBU (33 mL, 37 mg, 0.22 mmol). The solution was stirred for
12 h and then concentrated with a rotavapor. The resulting slurry
was subjected to column chromatography (CH2Cl2/MeOH, 250:1) to
give 24 as a dark brown solid (76 mg, 34%). 1H NMR (300 MHz,
1H), 9.60 (s, 1H), 8.99 (s, 1H), 8.62 (s, 1H), 8.33 (d, J¼7.2 Hz, 1H),
7.89–7.84 (m,1H), 7.45–7.41 (m,1H), 6.54 (s,1H), 6.48 (s 1H), 4.02 (s,
3H), 3.93–3.91 (m, 9H), 3.49–3.37 (m, 6H), 1.25–1.14 (m, 6H). MS
(MALDI-TOF): m/z 594.4 [MþH]þ. 13C NMR (100 MHz, CDCl3):
d
229.6, 167.9, 163.8, 162.0, 161.4, 154.9, 153.1, 150.8, 147.9, 145.8,
137.4, 130.6, 125.9, 125.6, 122.5, 122.0, 121.2, 120.4, 115.0, 114.6, 95.7,
95.2, 56.6, 56.5, 56.3, 56.1, 42.9, 41.0, 40.9, 29.7, 14.4, 13.0, 1.01.
CDCl3):
d 10.48 (s, 1H), 9.98 (s, 1H), 9.58 (s, 1H), 9.25 (s, 1H), 8.93–

K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
7727
HRMS (MALDI-FT): Calcd for C30H35N5O8Na [MþNa]þ: 616.2386.
(d, J¼8.4 Hz,1H), 7.07 (s,1H), 6.59(s,1H), 4.33 (s, 3H), 4.03(s, 3H), 3.92
(s, 3H), 3.89 (s, 3H), 3.57 (s, 4H),1.53 (s, 54H),1.11 (t, J¼7.2 Hz, 3H),1.04
Found: 616.23779.
(t, J¼7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3):
d 162.5, 162.4, 156.9,
4.21. Compound 46
150.4 (d), 150.2, 148.5, 148.3, 143.8, 143.7, 143.2, 143.1, 143.0, 142.1,
141.9, 141.5, 140.3, 138.3, 132.3, 132.1 (d), 131.6, 129.8, 129.6, 125.5,
122.4, 120.6, 110.3, 57.9, 56.6, 56.5, 56.3, 56.1, 42.8, 40.4, 35.0, 31.9,
31.8, 30.3, 30.2, 29.7, 29.5, 29.4, 29.3, 29.0, 26.7, 23.2, 22.7, 14.2, 14.1,
13.8,12.6,1.0. MS (MALDI-TOF): m/z 2246.7 [M]þ. HRMS (MALDI-FT):
Calcd for C153H104N8O8Zn [MþH]þ: 2244.7228. Found: 2244.7263.
1H NMR (300 MHz, CDCl3):
d 8.80 (s, 1H), 8.05 (s, 1H), 6.50 (s,
1H), 3.92 (s, 6H), 3.84 (s, 3H), 3.49 (s, 4H), 1.53 (s, 2H), 1.26 (s, 2H),
1.18 (s, 6H). MS (EI): m/z 378 [M]þ. 13C NMR (100 MHz, CDCl3):
d
168.8, 167.5, 165.5, 157.4, 152.4, 123.3, 120.4, 111.6, 95.7, 56.6, 55.9,
51.7, 31.7, 29.7, 14.4. Anal. Calcd for C19H26N2O8: C, 60.30; H, 6.93; N,
7.40. Found: C, 60.31; H, 6.94; N, 7.19.
4.26. Compound 4
4.22. Compound 9
1H NMR (300 MHz, CDCl3):
d 10.42 (s, 1H), 10.23 (s, 1H), 9.15 (s,
1H), 8.99–8.85 (m, 9H), 8.46 (d, J¼7.2 Hz,1H), 8.22–8.10 (m, 4H), 7.98
(s, 3H), 7.82–7.76 (m, 6H), 7.47–7.41 (m, 2H), 6.54 (s,1H), 4.34 (s, 3H),
4.02 (s, 3H), 3.83 (s, 3H), 3.29 (s, 4H), 1.15 (t, J¼7.5 Hz, 3H), 1.00 (t,
1H NMR (300 MHz, CDCl3):
d 9.03 (s, 1H), 8.92 (s, 1H), 6.58 (s,
1H), 4.03 (s, 3H), 3.96 (s, 3H), 3.89 (s, 3H), 4.03–3.89 (m, 4H), 1.40 (t,
J¼7.2 Hz, 3H), 1.30 (t, J¼7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3):
J¼7.5 Hz, 3H). 13C NMR (100 MHz, CDCl3):
d 161.7, 160.2, 156.7, 150.4
d
165.6, 162.7, 159.6, 158.2, 153.3, 145.2 (d), 144.9, 144.7, 144.6, 143.9,
(d), 150.2, 148.4, 148.3 (d), 142.5, 142.1, 142.0, 141.4, 140.0, 139.8,
137.4, 132.3, 132.2 (d), 131.6, 129.9, 129.7, 129.4, 129.1, 125.3, 122.4,
120.6, 109.6, 95.2, 58.0, 56.5, 56.4, 56.0, 42.2, 39.8, 35.5, 35.0, 31.8,
29.7, 29.6, 29.5, 29.3 (d), 29.2, 29.1, 29.0, 25.2, 23.2, 22.7, 14.2, 13.7,
12.7, 1.0. MS (MALDI-TOF): m/z 2155 [MþK]þ. HRMS (MALDI-FT):
Calcd for C152H102N8O7Zn [M]þ: 2214.7178. Found: 2214.7158.
143.1, 143.0 (d), 142.9, 142.3, 142.2 (d), 141.1, 141.0, 139.0, 124.0,
119.9, 111.9, 95.9, 77.2, 58.3, 56.7, 56.2, 51.9, 43.0, 40.5, 13.9, 12.8, 1.0.
MS (MALDI-TOF): m/z 1093.3 [MþNa]þ. HRMS (MALDI-FT): Calcd
for C77H22N2O6Na [MþNa]þ. 1093.1330. Found: 1093.1370.
4.23. Compound 1
4.27. Compound 5
To a stirred solution of 24 (10.0 mg, 0.0045 mmol) in CH2Cl2
(50 mL) was added a solution of zinc acetate (8.0 mg, 0.045 mmol)
in MeOH (3 mL). The solution was stirred for 12 h and then con-
centrated with a rotavapor. The resulting slurry was triturated with
CH2Cl2 (50 mL) and the organic phase washed with saturated
aqueous NaHCO3 (25 mL), water (25 mL) and brine (25 mL), and
dried over sodium sulfate. The solvent was then removed under
reduced pressure to afford 1 as a purple solid (8.5 mg, 82%). 1H NMR
1H NMR (300 MHz, CDCl3):
d 10.43 (s, 1H), 10.00 (s, 1H), 9.62 (s,
1H), 9.45 (s, 1H), 9.25 (d, J¼2.7 Hz, 1H), 9.03–8.96 (m, 8H), 8.84 (s,
1H), 8.30 (dd, J1¼8.3 Hz, J2¼2.4 Hz, 1H), 8.12–8.07 (m, 6H), 7.79–
7.78 (m, 3H), 7.40 (d, J¼8.4 Hz, 1H), 6.58 (s, 1H), 6.43 (s, 1H), 4.33 (s,
3H), 4.00 (s, 3H), 3.98 (s, 3H), 3.90 (s, 3H), 3.88 (s, 3H), 3.34 (s, 2H),
3.31–3.26 (m, 4H), 1.53 (s, 54H), 1.108 (t, J¼7.2 Hz, 3H), 1.039 (t,
J¼7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3):
d 167.7,163.8,162.6,157.0,
(300 MHz, CDCl3):
d
10.41 (s, 1H), 9.89 (s, 1H), 9.49 (s, 1H), 9.14 (s,
155.0, 150.5, 150.4 (d), 150.3, 148.6, 148.5 (d), 148.4, 145.9, 142.1,
142.0, 137.9, 136.3, 132.4, 132.1, 132.0, 131.8, 130.0, 129.7, 129.6,
122.4, 121.2, 120.8, 120.7, 115.5, 114.6, 109.8, 95.8, 95.1, 78.1, 78.0 (d),
77.9, 77.8, 56.6, 56.5, 56.4, 56.0, 42.8, 40.9, 40.7, 35.1, 35.0, 31.8 (d),
31.5 (d), 29.7, 14.3, 12.8. MS (MALDI-TOF): m/z 1560.1 [MþH]þ.
HRMS (MALDI-FT): Calcd for C94H108N8O9ZnNa [MþNa]þ:
1579.7472. Found: 1579.7423.
1H), 8.96–8.88 (m, 8H), 8.48 (s, 1H), 8.21 (d, J¼8.4 Hz, 1H), 8.11–7.97
(m, 7H), 7.72–7.72 (m, 3H), 7.26 (d, J¼8.4 Hz, 1H), 6.34 (s, 1H), 6.07
(s, 1H), 4.21 (s, 3H), 3.87 (s, 3H), 3.74 (s, 3H), 3.72 (s, 3H), 3.499 (s,
3H), 4.21–3.49 (m, 4H), 1.47 (s, 54H), 1.11 (t, J¼7.2 Hz, 3H), 1.04 (t,
J¼7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3):
d 162.3, 161.3, 156.9,
150.6, 150.5 (d), 150.3, 148.6, 148.5, 148.4, 145.0, 144.0, 143.9 (d),
142.9, 142.8, 142.3, 142.2, 142.1, 141.7 (d), 141.0, 140.4, 140.3, 136.4,
135.8, 132.3 (d), 132.2, 131.8 (d), 129.9, 129.8, 129.6, 128.3, 125.5,
122.6, 122.5, 121.8, 120.7, 119.7, 56.5, 56.3, 35.1, 34.2, 32.8, 31.9 (t),
31.8, 30.2, 29.7 (d), 29.5, 27.1, 23.2, 22.7, 14.2, 14.1, 13.9, 12.7. MS
(MALDI-TOF): m/z 2279.0 [MþH]þ. HRMS (MALDI-FT): Calcd for
C154H106N8O9Zn [MþH]þ: 2274.7448. Found: 2274.7369.
4.28. Compound 6
1H NMR (300 MHz, CDCl3):
d 10.60 (s, 1H), 10.15 (s, 1H), 9.74 (s,
1H), 9.65 (s, 1H), 9.18 (s, 1H), 9.01–8.97 (m, 6H), 8.88 (s, 1H), 8.83–
8.82 (m, 2H), 8.32 (d, J¼4.8 Hz, 1H), 8.08 (s, 7H), 7.78 (s, 3H), 7.63 (s,
1H), 6.60 (s, 1H), 6.44 (s, 1H), 4.05 (s, 3H), 4.00 (s, 3H), 3.93 (s, 3H),
3.89 (s, 3H), 3.39–3.27 (m, 6H), 1.15–1.06 (m, 6H). 13C NMR
4.24. Compound 2
(100 MHz, CDCl3):
d 167.8, 163.8, 162.0, 161.9, 154.9, 150.6, 150.4,
1H NMR (300 MHz, CDCl3):
d
10.41 (s, 1H), 9.95 (s, 1H), 9.56 (s,
150.3, 148.9, 148.8, 148.5, 148.4, 146.2, 146.0, 143.6, 142.2, 142.1,
132.9, 132.2, 132.0, 130.7, 129.9, 129.8, 129.7, 128.0, 122.5, 122.4,
120.7, 116.0, 114.8, 95.8, 95.2, 71.5, 56.5, 56.1, 49.3, 42.8, 40.9, 40.8,
36.4, 35.0, 31.8, 31.5, 31.3, 30.2, 29.7, 19.3, 17.5, 14.3, 13.9, 12.9. MS
(MALDI-TOF): m/z 1530.0 [MþH]þ. HRMS (MALDI-FT): Calcd for
C92H105N9O8ZnNa [MþNa]þ: 1550.7163. Found: 1550.72698.
1H), 9.08 (s, 1H), 8.97–8.94 (m, 7H), 8.83–8.82 (m, 2H), 8.45 (s, 1H),
8.28 (d, J¼4.8 Hz, 1H), 8.12–8.10 (m, 3H), 8.00–7.96 (m, 4H), 7.73 (s,
3H), 6.50 (s, 1H), 6.17 (s, 1H), 3.98 (s, 3H), 3.86 (s, 3H), 3.79 (s, 3H),
3.55 (s, 3H), 1.47 (s, 54H), 0.87–0.75 (m, 6H). 13C NMR (100 MHz,
CDCl3):
d 150.9, 150.7, 150.5, 148.9, 148.7, 148.5, 145.1, 143.8, 142.9,
142.3, 142.0, 141.9, 141.7, 140.3, 138.3, 132.6, 132.4, 129.8, 129.7,
129.6, 122.9, 120.9, 77.3, 71.5, 71.0, 61.8, 56.1, 35.1, 31.9, 31.8, 31.7,
29.7, 19.3, 14.1, 14.0, 13.9, 12.8. MS (MALDI-TOF): m/z 2250.5
[MþH]þ. MS-HR (MALDI-FT) Calcd for C152H103N9O8Zn [MþH]þ:
2245.7171. Found: 2245.7216.
4.29. Compound 7
1H NMR (300 MHz, CDCl3):
d 10.55 (s, 1H), 10.12 (s, 1H), 9.45 (s,
1H), 9.26 (d, J¼1.8 Hz, 1H), 9.02–8.96 (m, 8H), 8.83 (s, 1H), 8.30 (dd,
J1¼8.1 Hz, J2¼1.8 Hz, 1H), 8.18 (s, 1H), 8.13–8.11 (m, 6H), 7.81 (s, 3H),
7.73 (dd, J1¼8.1 Hz, J2¼1.5 Hz, 1H), 7.39 (d, J¼8.7 Hz, 1H), 6.90 (d,
J¼9H, 1H), 6.61 (s, 1H), 4.33 (s, 3H), 4.03 (s, 3H), 3.93 (s, 3H), 3.89 (s,
3H), 3.34–3.17 (m, 6H), 1.56 (s, 54H), 1.15 (t, J¼7.2 Hz, 3H), 1.06 (t,
J¼7.2 Hz, 3H). MS (MALDI-TOF): m/z 1529 [M]þ. 13C NMR (100 MHz,
4.25. Compound 3
1H NMR (300 MHz, CDCl3):
d 10.59 (s, 1H), 9.30 (s, 1H), 9.19 (d,
J¼2.1 Hz, 1H), 9.14 (s, 1H), 9.01–8.92 (m, 8H), 8.82 (s, 1H), 8.31 (dd,
J1¼8.3 Hz, J2¼1.8 Hz, 1H), 8.14–8.09 (m, 7H), 8.14–8.09 (m, 4H), 7.42
CDCl3):
d 167.4, 164.4 (d), 162.6, 156.9, 150.5, 150.4, 150.3, 148.6,

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K. Wang et al. / Tetrahedron 65 (2009) 7718–7729
148.5, 148.4 (d), 146.1, 142.1, 142.0, 136.4, 132.4, 132.1, 132.0, 131.7,
129.9, 129.7, 129.6, 127.8,127.2, 124.7,122.3, 120.9, 120.7, 117.9, 110.0,
109.9, 95.8, 56.7, 56.5, 56.4, 56.1, 53.4, 49.2, 42.7, 40.8, 35.1, 35.0,
31.8, 31.6, 31.5, 29.8, 29.7, 28.9, 17.4, 14.3, 12.8, 1.0. HRMS (MALDI-
FT): Calcd for C93H106N8O8Zn [M]þ: 1526.7457. Found: 1526.7420.
TOF): m/z 459 [MþH]þ. HRMS (MALDI-FT): Calcd for C23H30N4O6Na
[MþNa]þ: 481.2074. Found: 481.2058.
4.34. Compound 38
1H NMR (300 MHz, CDCl3):
d 8.70 (s, 1H), 8.41 (s, 1H), 8.38 (s,
4.30. Compound 8
1H), 8.23 (d, J¼7.5 Hz, 1H), 7.97 (s, 1H), 7.70 (t, J¼8.4 Hz, 1H), 6.53 (s,
1H), 3.90 (s, 3H), 3.88 (s, 3H), 3.65 (s, 2H). 13C NMR (100 MHz,
1H NMR (300 MHz, CDCl3):
d 10.50 (s, 1H), 9.24 (s, 1H), 9.09 (s,
CDCl3):
d 141.6, 137.2, 133.0, 130.0, 126.0, 121.9, 120.6, 108.2, 96.7,
56.8, 56.1. MS (ESI): m/z 318 [MþH]þ. HRMS (MALDI-FT): Calcd for
1H), 9.01–8.90 (m, 8H), 8.77 (s, 1H), 8.32 (s, 1H), 8.29 (s, 1H), 8.12–
8.10 (m, 6H), 7.79 (s, 3H), 7.62 (s, 1H), 7.58 (d, J¼7.2 Hz, 1H), 7.36 (d,
J¼8.4 Hz,1H), 7.22 (d, J¼8.4 Hz,1H), 6.49 (s,1H), 4.29 (s, 3H), 3.98 (s,
3H), 3.81 (s, 3H), 2.71 (d, J¼6.6 Hz, 2H), 2.47 (d, J¼6.6 Hz, 2H), 0.72
(t, J¼6.9 Hz, 3H), 0.61 (t, J¼6.9 Hz, 3H). 13C NMR (100 MHz, CDCl3):
C15H16N3O5 [MþH]þ: 318.1083. Found: 318.1085.
4.35. Compound 40
d
166.6, 164.9, 163.4, 162.6, 156.9, 150.4, 150.3, 150.2 (d), 148.5, 148.4
A suspension of 39 (0.82 g, 0.62 mol) and Raney Ni (0.10 g) in
THF was stirred under the bubble of hydrogen gas for 4 h and then
filtrated. The filtrate was concentrated to give 40 as a purple solid
(d), 142.3, 142.2, 138.0, 135.8, 132.3, 132.0 (d), 131.6, 129.9, 129.8,
129.7, 129.1, 123.3, 122.2, 121.3, 120.6, 120.4, 117.9, 109.8, 95.6, 56.6,
56.4, 56.1, 42.2, 40.2, 38.0, 35.0, 31.8, 31.5, 29.7, 14.0, 12.4. MS
(MALDI-TOF): m/z 1500.2 [MþH]þ. HRMS (MALDI-FT): Calcd for
C92H105N8O7Zn [MþH]þ: 1497.7436. Found: 1497.7392.
(0.80 g, 100%). 1H NMR (300 MHz, CDCl3):
d 10.54 (s, 1H), 9.48 (s,
1H), 9.27 (d, J¼2.7 Hz, 1H), 8.92–8.87 (m, 7H), 8.30 (dd, J1¼8.7 Hz,
J2¼1.8 Hz, 1H), 8.12–8.08 (m, 6H), 7.80 (s, 3H), 7.49 (d, J¼8.4 Hz, 1H),
7.20–7.15 (m, 3H), 6.99 (s, 1H), 6.74 (t, J¼2.4 Hz, 1H), 6.62 (s, 1H),
4.34 (s, 3H), 4.04 (s, 3H), 3.92 (s, 3H), 3.78 (s, 2H), 1.54 (s, 54H),
4.31. Compound 32
ꢁ2.68 (s, 2H). 13C NMR (100 MHz, CDCl3):
d 62.6, 157.1, 148.8, 148.7,
A solution of 18 (1.19 g, 12.0 mmol), 31 (2.17 g, 12.0 mmol) and
DCC (2.97 g, 14.4 mmol) in CH2Cl2 (50 mL) was stirred for 12 h and
then washed with diluted aqueous HCl (0.1 N, 25 mL), water
(25 mL) and brine (25 mL), and dried over sodium sulfate. The
solvent was removed and the resulting slurry subjected to flash
chromatography (CH2Cl2/MeOH 100:1) to give 32 as a pale grey
148.6 (d), 146.8, 141.4 (d), 140.0, 138.0, 135.8, 130.0, 129.8 (d), 129.6,
129.3, 125.5, 121.7, 121.4, 120.9, 120.8, 120.7, 117.8, 116.5, 115.6, 114.1,
110.0, 95.7, 78.8, 56.7, 56.5, 56.3, 35.1, 34.9, 31.8, 30.4, 29.7, 29.5,
23.9, 1.0. MS (MALDI-TOF): m/z 1295.8 [MþH]þ. HRMS (MALDI-FT):
Calcd for C85H96N7O5 [MþH]þ: 1294.7486. Found: 1294.7467.
solid (2.49 g, 63%). 1H NMR (300 MHz, CDCl3):
d 10.35 (s, 1H), 8.99
Acknowledgements
(s, 1H), 7.82 (d, J¼9.9 Hz, 1H), 6.92 (d, J¼8.4 Hz, 1H), 3.98 (s, 3H),
3.88 (s, 3H), 3.49 (s, 2H), 3.47–3.37 (m, 4H), 1.24 (t, J¼7.5 Hz, 3H),
We thank the National Natural Science Foundation of China
(Nos. 20621062, 20672137, 20732007, and 20872167), the National
Basic Research Program (2007CB808001) and the Science and
Technology Commission of Shanghai Municipality (09XD1405300)
for financial support.
1.170 (t, J¼7.5 Hz, 3H). 13C NMR (100 MHz, CDCl3):
d 167.5, 166.9,
164.4,152.3, 127.3, 126.4, 122.8, 121.4, 109.5, 56.1, 51.9, 42.8, 40.9 (d),
14.4, 12.9. MS (EI): m/z 322 [M]þ. Anal. Calcd for C16H22N2O5: C,
59.61; H, 6.88; N, 8.69. Found: C, 59.38; H, 7.05; N, 8.33.
4.32. Compound 33
References and notes
A solution of 32 (0.26 g, 0.82 mmol) and lithium hydroxide mon-
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stirred for 2 h and then concentrated. The resulting slurry was tritu-
rated with CHCl3 (20 mL). After workup, the crude product was
recrystallized from MeOH to give 33 as a white solid (0.19 g, 76%). 1H
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