Complete assignment of the1H and13C NMR spectra of resveratrol derivatives

Article abstract of DOI:10.1002/mrc.910

Contract/grant sponsor: Korea Ministry of Marine Affairs and Fishery The complete ¹H and ¹³C chemical shift assignments of six derivatives of resveratrol [(E)-5-[2-(4-hydroxyphenyl)ethenyl]-1,3-benzenediol] that possess leukotriene D

Full text of DOI:10.1002/mrc.910

MAGNETIC RESONANCE IN CHEMISTRY
Magn. Reson. Chem. 2001; 39: 768–770
Spectral Assignments and Reference Data
Complete assignment of the 1H and 13C
NMR spectra of resveratrol derivatives
its well-known activity against cell proliferation, is also known to
exhibit antagonistic activity against leukotriene D4 (LTD4) receptors.
In order to improve this anti-LTD4 activity, we have previously
1
carried out structural modifications based on structure–activity.
1
2
3
The present work deals with the structural elucidation of synthesized
trimethoxystilbene derivatives of resveratrol. For these derivatives,
dimethoxy groups are located at positions 3 and 5, but the third
methoxy group can be positioned as an ortho, meta or para substituent
in the other phenyl ring. Since the molecule can be in either the cis
or trans configuration, a total of six isomers exist (Scheme 1). In
Dongsoo Koh, Kwan Ha Park, Jihyun Jung,
3
4
3∗
Heejung Yang, K. Hun Mok and Yoongho Lim
1
Department of Applied Chemistry, Dongduk Women’s University, Seoul
36-716, Korea
Department of Marine Biomedical Sciences, Kunsan National Univer-
sity, Chonbuk 573-702, Korea
Department of Applied Biology and Chemistry, Konkuk University,
Seoul 143-701, Korea
Oxford Centre for Molecular Sciences, New Chemistry Laboratory,
University of Oxford, Oxford OX1 3QH, UK
1
2
0
1
the case of 3,5-dimethoxyphenyl-4 -methoxyphenylethene, the H
1
3
and C NMR data were easily assigned because of its symmetric
structure. However, the complete assignments of the ortho and
meta isomers were difficult because of very close chemical shifts
for the protons at the double bond and those of the two phenyl
3
4
1
13
groups. We report here the complete H and C NMR chemical
shift assignments for 2–7 on the basis of COSY, HMQC, HMBC
and NOESY experiments, along with computer-aided molecular
modeling (CAMM).
Received 9 May 2000; Revised 31 May 2001; Accepted 20 June 200l
The complete 1H and 13C chemical shift assign-
ments of six derivatives of resveratrol [(E)-5-[2-(4-
hydroxyphenyl)ethenyl]-1,3-benzenediol] that possess
leukotriene D4 receptor antagonistic activities are
described. Two-dimensional COSY, HMQC, HMBC and
NOESY experiments, along with molecular modeling cal-
culations, were employed to distinguish unambiguously
between different configurations of the stilbene moiety.
Copyright  2001 John Wiley & Sons, Ltd.
OH
HO
OH
KEYWORDS: NMR; 1H NMR; 13C NMR; resveratrol; structure
1
INTRODUCTION
Resveratrol [(E)-5-[2-(4-hydroxyphenyl)ethenyl]-1,3-benzenediol] is
a stilbene derivative naturally found in the bark of Morus alba
and also in the skin of grapes (Vitis vinifera), and in addition to
RESULTS AND DISCUSSION
Most of the 1H and 13C chemical shift assignments of 2–7 were
achieved in a straightforward manner. Two H signals at 7.02 and
1
0
7
.45 ppm of trans-3,5-dimethoxyphenyl-2 -methoxyphenyl ethene
Ł
(2) were found to be correlated with each other and were observed
Correspondence to: Prof. Yoongho Lim, Department of Applied Biology and
Chemistry, Konkuk University, Hwayang-Dong 1, Kwangjin-Ku, Seoul
1
to share the same coupling constant value (16.4 Hz). In addition,
HMQC spectra indicated that these protons were attached to 1
3
C
43-701, Korea. E-mail: yoongho@konkuk.ac.kr
Contract/grant sponsor: Korea Ministry of Marine Affairs and Fishery.
signals observed at 129.6 and 124.5 ppm belonging to the ethenyl
Table 1. Complete assignments of the NMR data of derivatives 2 and 3
2
3
Assignment
υ13
C
υ1H (J, Hz)
CHn
υ13
C
υ1H (J, Hz)
CHn
1
2
3
4
5
6
7
8
140.5
105.1
161.5
100.3
161.5
105.1
129.6
124.5
126.7
157.5
111.4
129.3
121.2
127.0
—
6.68 (d, 2.2)
—
s
d
s
139.6
107.2
160.9
100.3
160.9
107.2
130.7
126.9
126.7
157.7
111.1
129.3
120.7
130.8
—
6.39 (d, 2.3)
—
s
d
s
6.36 (t, 2.2)
—
d
s
6.26 (t, 2.3)
—
d
s
6.68 (d, 2.2)
7.02 (d, 16.4)
7.45 (d, 16.4)
—
d
d
d
s
6.39 (d, 2.3)
6.53 (d, 12.2)
6.69 (d, 12.2)
—
d
d
d
s
0
1
0
2
—
s
—
s
0
3
6.83 (d, 8.2)
7.20 (dd, 7.5, 8.2)
6.92 (dd, 7.5, 7.5)
7.55 (d, 7.5)
d
d
d
d
6.82 (d, 8.2)
7.15 (dd, 7.5, 8.2)
6.75 (dd, 7.5, 7.5)
7.22 (d, 7.5)
d
d
d
d
0
4
0
5
0
6
3-OMe
5
5.8
3.77 (s)
3.82 (s)
q
q
55.5
55.9
3.55 (s)
3.74 (s)
q
q
5
2
-OMe
0
-OMe
55.9
DOI: 10.1002/mrc.910
Copyright  2001 John Wiley & Sons, Ltd.

769
Spectral Assignments and Reference Data
The 1H and 13C NMR data for cis-3,5-dimethoxyphenyl-2 -
methoxyphenylethene 3 could be easily assigned based on the results
for 2. Its complete assignments are listed in Table 1. Unlike 2 and 3,
0
MeO
MeO
MeO
MeO
1
OMe
2′
0
0
0
0
7
1′
in order to distinguish between H-2 , H-4 , H-5 and H-6 of trans-3,5-
0
3
8
dimethoxyphenyl-3 -methoxyphenylethene 4, NOESY spectra and
OMe
2
′
CAMM calculations were performed. While the distance between
0 0
˚
the 3 -methoxy protons and H-4 was 3.8 A, the distances between the
MeO
0
0
0
0
H-5 and 3 -methoxy protons and the H-6 and 3 -methoxy protons
2
4
3
were 5.7 and 6.1 A˚ , respectively. In the former case, the NOE signal
would be expected to be strong, whereas in the latter cases it would
be weak. As shown in Fig. 1, while an NOE cross peak between the
MeO
MeO
0
signals at 6.77 and 3.75 ppm assigned to 3 -methoxy protons could
be observed, those among 7.05 and 3.75 ppm or 7.21 and 3.75 ppm
1
could not be found. As a result, the H resonance at 6.77 ppm is
3
′
MeO
MeO
3′
OMe
OMe
0
assigned to H-4 . According to calculations by CAMM, the distance
OMe
0
0
˚
between the 3 -methoxy protons and H-2 was predicted to be 2.4 A,
and this was to be found so in the NOESY spectrum (Fig. 1) where
the signal at 3.75 ppm shows another strong cross peak at 7.00 ppm,
5
0
hence allowing its assignment to H-2 . Complete assignments of the
NMR data of derivative 4 are listed in Table 2.
4
′
OMe
OMe
MeO
4′
OMe
3.65
3.70
3.75
6
7
Scheme 1. Structures of resveratrol derivatives 2—7.
3
3
3
.80
.85
.90
group C-7orC-8, respectively. Derivative 2was therefore determined
to be in the trans configuration based on these observations. Long-
0
1
range couplings amongst C-2 and three H signals at 7.20, 7.55,
and 7.45 ppm were observed from the HMBC spectra. From the
1
COSY spectrum, the H signal at 7.20 ppm was correlated with 6.83
1
and 6.92 ppm, allowing the four H signals at 6.83, 6.92, 7.20, and
3.95
0 0 0 0
.55 ppm to be assigned to H-3 , H-4 , H-5 and H-6 , respectively.
7
1
3
Their corresponding C signals were at 111.4, 121.2, 129.3, and
4.00
1
1
27.0 ppm, respectively. The H signal at 7.45 ppm belonging to the
7.3
7.2
7.1
7.0
6.9
6.8
ethenyl group was found to be H-8 due to long-range coupling to
three C signals at 127.0 (doublet), 140.5 (singlet) and especially
57.5 ppm (singlet, C-2 ). Complete assignments of these and all
ppm
1
3
0
1
Figure 1. NOESY spectrum between 6.7 and 7.3 ppm (t
4.0 ppm (t ) of derivative 4.
2
) and 3.6 and
1
13
other H and C NMR data of 2 are listed in Table 1.
1
Table 2. Complete assignments of the NMR data of derivatives 4 and 5
4
5
Assignment
υ13
C
υ1H (J, Hz)
CHn
υ13
C
υ1H (J, Hz)
CHn
1
2
3
4
5
6
7
8
138.6
103.9
160.3
99.4
—
6.64 (d, 2.2)
—
s
d
s
139.5
107.2
160.9
100.3
160.9
107.2
130.8
130.9
138.9
114.3
159.8
113.7
129.6
121.9
—
6.43 (d, 2.3)
—
s
d
s
6.37 (t, 2.2)
—
d
s
6.31 (t, 2.3)
—
d
s
160.3
103.9
128.3
128.4
137.9
111.2
159.2
112.7
128.9
118.6
6.64 (d, 2.2)
6.97 (d, 16.3)
7.01 (d, 16.3)
—
d
d
d
s
6.43 (d, 2.3)
6.53 (d, 12.2)
6.58 (d, 12.2)
—
d
d
d
s
0
1
0
2
7.00 (s)
d
s
6.82 (dd, 2.6, 1.6)
—
d
s
0
3
—
0
4
0
6.77 (d, 8.1)
7.21 (dd, 7.7, 8.1)
7.05 (d, 7.7)
d
d
d
6.74 (dd, 2.6, 7.9)
7.15 (dd, 7.9, 7.6)
6.86 (dd, 1.6, 7.6)
d
d
d
5
0
6
3-OMe
5
4.4
3.74 (s)
3.75 (s)
q
q
55.6
55.5
3.64 (s)
3.67 (s)
q
q
5
3
-OMe
0
-OMe
54.5
Copyright  2001 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2001; 39: 768–770

770
Spectral Assignments and Reference Data
Table 3. Complete assignments of the NMR data of derivatives 6 and 7
6
7
Assignment
υ13
C
υ1H (J, Hz)
CHn
υ13
C
υ1H (J, Hz)
CHn
1
2
3
4
5
6
7
8
140.1
104.7
161.4
100.0
161.4
104.7
126.9
129.1
130.3
128.2
114.5
159.8
114.5
128.2
—
s
d
s
138.7
105.8
159.8
98.9
—
s
d
s
6.65 (d, 2.2)
—
6.43 (d, 2.2)
—
6.37 (t, 2.2)
—
d
s
6.31 (t, 2.2)
—
d
s
159.8
105.9
127.9
129.4
128.8
129.5
112.8
158.0
112.8
129.5
6.65 (d, 2.2)
6.90 (d, 16.0)
7.03 (d, 16.0)
—
d
d
d
s
6.43 (d, 2.2)
6.44 (d, 12.8)
6.51 (d, 12.8)
—
d
d
d
s
0
1
0
2
7.44 (d, 8.8)
6.88 (d, 8.8)
—
d
d
s
7.20 (d, 8.4)
6.75 (d, 8.4)
—
d
d
s
0
3
0
4
0
5
6.88 (d, 8.8)
7.44 (d, 8.8)
d
d
6.75 (8.4)
7.20 (d, 8.4)
d
d
0
6
3-OMe
5
5.72
3.82 (s)
3.82 (s)
q
q
54.4
54.4
3.65 (s)
3.76 (s)
q
q
5
4
-OMe
0
-OMe
55.76
The 1H and 13C NMR data for cis-3,5-dimethoxyphenyl-30-
methoxyphenylethene (5) could be assigned in the same manner
as for 4 and its complete assignments are listed in Table 2. For 6
and 7, since the two phenyl groups are symmetric, all signals of the
H and C NMR data could be easily determined. Their complete
assignments are listed in Table 3.
were acquired with a 1 s relaxation delay using 32 K data points.
pulse was 9.7 µs with a spectral width of 4 kHz. 1
C
3
The 90
NMR and DEPT spectra were obtained for a spectral width of
pulse was 9.6 µs. Two-
°
8 kHz, collecting 64 K data points. The 90
°
1
13
dimensional spectra were acquired with 2048 data points for t2 and
256 for t1 increments.
As shown in Tables 1–3, regardless of the substituted position
ortho, meta or para) of the monomethoxy group, the H chemical
1
(
Calculations
shifts of trans isomers were observed more downfield shifted than
those of the corresponding cis isomers. Therefore, the trans and cis
isomers of the derivatives commonly possessing the stilbene moiety
All calculations were performed using MSI (San Diego, CA,
USA) software on a Silicon Graphics INDY R4400 workstation.
The potentials were arranged using a consistent valence force
field and the calculation was performed for 500 ps. Among
1
could be distinguished through the comparison of the H NMR data.
5
00 calculated structures, 10 structures with the lowest total energy
were superimposed.
EXPERIMENTAL
Materials
Acknowledgement
Derivatives 2–7 were prepared according to the published
The authors are grateful to the Korea Ministry of Marine Affairs and
Fishery (The Korea Sea Grant Program 2000).
3
procedures. Wittig reaction of 3,5-dimethoxybenzaldehyde with
the corresponding methoxybenzylphosphonium chloride in a two-
phase solvent system (aqueous NaOH and CH2Cl2) furnished a
mixture of trans (2, 4 and 6) respectively) and cis (3, 5 and 7) deriva-
tives in 78–87% yield. Column chromatographic separation gave the
corresponding pure trans and cis isomers.
REFERENCES
1
2
3
. Koh D, Park KH, Lee H, Jung J, Kim K, Cho S, Lim Y. Agric. Chem.
Biotechnol. 2000; 43: 281.
. Breitmaier E, Voelter W. Carbon-13 NMR Spectroscopy. VCH: New
York, 1987.
. Zhang F-J, Harvey RG. J. Org. Chem. 1998; 63: 2771.
NMR spectra
All NMR measurements were performed on a Bruker Avance 400
spectrometer system (9.4 T) at 298 K. The 1H NMR, C NMR,
DEPT, COSY, HMQC, HMBC and NOESY spectra were collected
13
4
4. Jung J, Kim L, Lee C, Cho Y, Ahn S, Lim Y Magn. Reson. Chem.
2001; 39: 406–410.
in CDCl3 with TMS as an internal reference. The concentration
of the samples was 50 mM. For H NMR analysis, 16 transients
1
Copyright  2001 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2001; 39: 768–770