1H and 13C NMR spectral assignments of novel chromenylchalcones

Article abstract of DOI:10.1002/mrc.3873

Several types of chalcones containing 2H-chromen group were synthesized. Claisen-Schmidt condensation of 2H-chromen-3-carbaldehydes (I) with methoxy substituted acetophenones afforded (E)-3-(2H-chromen-3-yl)-1-(methoxyphenyl) prop-2-en-1-ones (chromenylchalcones, 1-7). Other types of chromenylchalcone, (E)-1-(6-methoxy-2H-chromen-3-yl)-3-(methoxyphenyl)prop-2-en-1-ones (8-13) were also obtained between reaction of methoxy substituted benzaldehydes and 1-(6-methoxy-2H-chromen-3-yl)ethanone (II). Dichromenylchalcones (14-16) were also synthesized through the same reaction between aldehydes (I) and ketone (II). Their complete ¹H-NMR and ¹³C-NMR assignments are reported here and more polysubstituted chromenylchalcones synthesized or isolated from the natural sources in the future can be identified on the basis of the NMR data reported here. Copyright

Full text of DOI:10.1002/mrc.3873

MRC Letters
Received: 31 May 2012
Revised: 19 August 2012
Accepted: 20 August 2012
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/mrc.3873
1H and C NMR spectral assignments of novel
13
chromenylchalcones
Hyuk Yoon,a Seunghyun Ahn,b Doseok Hwang,a Geunhyeong Jo,a
Dong Woon Kim,c Sang Ho Kim,c Dongsoo Kohb and Yoongho Lima*
Several types of chalcones containing 2H-chromen group were synthesized. Claisen–Schmidt condensation of 2H-chromen-3-
carbaldehydes (I) with methoxy substituted acetophenones afforded (E)-3-(2H-chromen-3-yl)-1-(methoxyphenyl)prop-2-en-1-
ones (chromenylchalcones, 1–7). Other types of chromenylchalcone, (E)-1-(6-methoxy-2H-chromen-3-yl)-3-(methoxyphenyl)
prop-2-en-1-ones (8–13) were also obtained between reaction of methoxy substituted benzaldehydes and 1-(6-methoxy-2H-
chromen-3-yl)ethanone (II). Dichromenylchalcones (14–16) were also synthesized through the same reaction between
1
aldehydes (I) and ketone (II). Their complete H-NMR and 13C-NMR assignments are reported here and more polysubstituted
chromenylchalcones synthesized or isolated from the natural sources in the future can be identified on the basis of the NMR
data reported here. Copyright © 2012 John Wiley & Sons, Ltd.
Keywords: NMR; 1 H NMR; 13C NMR; 2D NMR; flavonoid; chalcone
methylvinylketone followed by intramolecular aldol condensa-
tion accounts for the formation of chromene aldehydes (I) or
Introduction
Chalcones are one of the secondary metabolites in plants and
belong to a flavonoid class with C6-C3-C6 skeletone, which are
named A, C, and B-ring [Fig. 1{A)]. Instead of a closed C-ring of
flavonoid, however, C3 skeleton of chalcone is a,b-unsaturated
carbonyl group [Fig. 1(B)]. Because of their diverse biological
activities, various chalcones have been isolated from natural
sources and synthesized, and their NMR data have been
reported.[1–3] Benzoflavones are one of the flavonoids, too, and
contain one more benzene ring attached to A-ring [Fig. 1(C)].
It has been known that they act as potent inhibitors of breast
cancer resistance protein.[4,5] Because of diverse biological activities
of chalcones and benzoflavones, we designed three types of novel
chromenylchalcones combined with chalcone and chromenes,
which are analogs of benzoflavone, and synthesized them: seven
(E)-3-(2H-chromen-3-yl)-1-phenylprop-2-en-1-ones [Fig. 1(D)], six
(E)-1-(6-methoxy-2H-chromen-3-yl)-3-phenylprop-2-en-1-ones [Fig. 1
(E)], and three (E)-3-(2H-chromen-3-yl)-1-(6-methoxy-2H-chromen-3-yl)
prop-2-en-1-ones [Fig. 1(F)]. Because their NMR data can help us
identify newly isolated or synthesized chromenylchalcone deriva-
chromene methyl ketone (II). Claisen–Schmidt condensation of
chromene aldehydes (I) with methoxy substituted acetophenone
under basic conditions afforded (E)-3-(2H-chromen-3-yl)prop-2-en-1-
ones (chromenylchalcones, 1–7) as we described in the previous
report.[6] When chromene methyl ketone (II) was treated with
methoxy substituted benzaldehydes under the same conditions,
other types of chromenylchalcone 8–13 were also obtained.
Dichromenylchalcones (14–16) were synthesized through the
same reaction between chromene aldehydes (I) and chromene
methyl ketone (II). To confirm the structures of the synthetic
compounds, mass spectrometry was performed on a high-resolution
electron impact ionization mass spectrometer (HREIMS, JMS700, Jeol
Ltd., Tokyo, Japan).
NMR spectra
The synthetic chromenylchalcones were dissolved in DMSO-d6.
1
The H and 13C chemical shifts of the deuterated solvent were
2.50 and 39.5 ppm referenced to TMS, respectively. The NMR
samples were prepared at approximately 50 mM, and they
were transferred to a 2.5-mm NMR tube. All NMR experiments
were carried out on a Bruker Avance 400 spectrometer system
1
tives, we report here the complete H and 13C NMR data of 16
chromenylchalcones (Fig. 2).
Experimental
*
Correspondence to: Yoongho Lim, Division of Bioscience and Biotechnology, BMIC,
Konkuk University, Hwayang-Dong 1, Kwangjin-Ku, Seoul 143-701, South Korea.
Email: yoongho@konkuk.ac.kr
Synthesis
All of the chromenylchalcone derivatives (1–16) were synthe-
sized as shown in Scheme 1. Methoxy or bromo substituted
salicylaldehydes were treated with acrolein in the presence
of K2CO3 in dioxane to give corresponding 2H-chromen-3-
carbaldehydes (I). When the same conditions were applied in
reaction between 5-methoxy salicylaldehyde and methylvinylketone,
1-(6-methoxy-2H-chromen-3-yl)ethanone (II) was obtained in
good yield. Michaels addition of salicylaldehydes to acrolein or
a Division of Bioscience and Biotechnology, BMIC, Konkuk University, Seoul 143-701,
South Korea
b Department of Applied Chemistry, Dongduk Women’s University, Seoul 136-714,
South Korea
c
Swine science division, National Institute of Animal Science, RDA, Cheonan
330-801, South Korea
Magn. Reson. Chem. (2012)
Copyright © 2012 John Wiley & Sons, Ltd.

H. Yoon et al.
O
(A)
(C)
(B)
(D)
B
β
O
1'
α
1
1'
A
2
3
B
A
5
C
O
O
B
O
A
1
C
2'
O
O
(E)
O
MeO
1'
2
O
(F)
O
MeO
2
2'
O
O
Figure 1. Structures of (A) flavone, (B) chalcone, (C) benzoflavone, (D)
(E)-3-(2H-chromen-3-yl)-1-phenylprop-2-en-1-one, (E) (E)-1-(6-methoxy-2H-
chromen-3-yl)-3-phenylprop-2-en-1-one, and (F) (E)-3-(2H-chromen-3-yl)-1-
(6-methoxy-2H-chromen-3-yl)prop-2-en-1-one.
(9.4 T; Bruker, Karlsruhe, Germany) at 298 K. For the 1 H NMR
analyses, 16 transients were acquired with a 1 s relaxation
delay using 32 K data points. The 90o pulse duration was of
11.8 ms, and the spectral width was 4800 Hz. The 13C NMR
spectra were obtained with a spectral width of 21,000 Hz using
64 K data points. The 90o pulse duration was of 15.0 ms. For the
two-dimensional experiments including COSY, TOCSY, NOESY,
HMQC, and HMBC, all data were acquired with 2 K Â 256 data
points (t2 Â t1). The mixing time for the NOESY experiment
was 1 s, and the long-range coupling time for HMBC was 70 ms.
Zero-filling of 2 K and the sine-squared bell window function were
applied before Fourier transformation using XWin-NMR (Bruker).[7]
All NMR data were analyzed using Sparky.[8]
Results and Discussion
All chromenylchalcone derivatives (1–16) are novel. The procedure
to assign the NMR data of chromenylchalcone 16, (E)-1-(6-methoxy-
\2H-chromen-3-yl)-3-(8-methoxy-2H-chromen-3-yl)prop-2-en-1-one,
is explained in detail here. Twenty-three peaks were observed in the
13C NMR spectrum. Of them, the most downfield shifted peak at
186.2 ppm was caused by the carbon of ketone group. It showed
1
long-ranged couplings with the H peaks at 7.14 and 7.35 ppm in
the HMBC spectrum, which were attached to the 13C peaks at
120.0 and 139.4 ppm in the HMQC spectrum, respectively, so that
they were assigned C-a and C-b, respectively. In addition, a cross
peak between two protons at 7.14 and 7.35 ppm was observed in
the COSY spectrum. Because H-b was correlated with two protons
at 5.11 and 7.10 ppm attached to two carbons at 65.6 (triplet
carbon) and 131.5 (doublet carbon), respectively; they were
Figure 2. Structures, nomenclature, and HREIMS data of chromenyl-
chalcones 1–16.
wileyonlinelibrary.com/journal/mrc
Copyright © 2012 John Wiley & Sons, Ltd.
Magn. Reson. Chem. (2012)

1H and 13C NMR spectral assignments of novel chromenylchalcones
O
O
O
O
O
determined to be H-2’ and H-4’, respectively. In the HMBC spectrum,
C-4’ was long-range coupled to the proton at 6.81 ppm, and it was
assigned H-5’. C-5’ (120.0ppm), determined on the basis of the
HMQC spectrum, showed a long-ranged coupling with the proton
at 6.98 ppm, so that it was determined H-7’. From the interpretation
of the COSY spectrum, the 1H peak at 6.90 ppm was assigned H-6’.
Because of the long-ranged coupling between the carbon peak at
147.4ppm and H-6’ was observed in the HMBC spectrum, it was
C-8’. The methoxy proton at 3.79 ppm showed a long-ranged
coupling with C-8’, so that it was assigned 8’-OMe. The carbon
(143.1 ppm) showing long-range couplings with H-5’ and H-7’
was determined C-9’. Because the 13C at 122.7 ppm was long-
range coupled to H-6’, it was C-10’. Of the two methoxy
carbons at 55.7 and 55.5 ppm, because the former was assigned
8’-OMe, the later should be 6-OMe. The carbon showing the
long-range coupling with the proton of 6-OMe at 3.75 ppm was
observed at 154.0 ppm, which was assigned C-6. The proton at
6.85 ppm showing the long-ranged coupling with C-6 was H-8.
Likewise, the carbon observed at 121.6 ppm was C-10. A triplet
carbon at 63.8 ppm was C-2. From the interpretation of HMBC,
MeO
CH
CH
H
3
3
H
H
O
O
OH
R = OMe, Br
K CO
K CO
2 3
R
2
3
R
II
I
O
O
H
KOH,
EtOH
KOH,
EtOH
CH
3
MeO
OMe
O
O
MeO
MeO
O
O
OMe
R
8 - 13
1 - 7
O
O
O
MeO
H
MeO
CH
3
KOH
+
O
O
EtOH
MeO
O
O
OMe
I
14 - 16
II
Scheme 1. Synthetic methods used to prepare chromenylchalcones 1–16.
Table 1. The 1 H NMR chemical shifts of chromenylchalcones 1–16
d of 1H (J, Hz)
Position
1
2
3
4
5
6
7
8
2
3
4
8.12(d, 8.8)
7.08(d, 8.8)
—
7.22(d, 2.3)
—
8.10(d, 8.7)
7.07(d, 8.7)
—
—
7.18(d, 8.4)
7.54 (ddd, 1.8,
7.4, 8.4)
7.49(d, 2.7)
—
—
7.19(d, 8.4)
7.54 (ddd, 2.0,
7.5, 8.4)
7.22(d, 2.2)
—
4.96(s)
—
6.79(d, 2.3)
7.23(dd,
2.7, 7.9)
6.80(d, 2.2)
8.06(s)
5
6
7.08(d, 8.8)
8.12(d, 8.8)
—
7.07(d, 8.7)
8.10(d, 8.7)
7.06(d, 7.4)
7.48(dd,
7.49(d, 7.9)
7.62(d, 7.9)
7.06(d, 7.5)
7.43(dd,
2.0, 7.5)
—
6.98(d, 3.0)
7.22(d, 2.3)
7.22(d, 2.2)
—
1.8, 7.4)
7
—
—
—
—
—
—
—
6.93(dd,
3.0, 8.8)
8
—
5.10(s)
7.08(s)
6.82(m)
—
—
5.10(s)
7.12(s)
6.82(m)
—
—
5.14(s)
7.08(s)
7.14(d, 8.4)
6.55(dd,
2.2, 8.4)
—
—
4.98(s)
7.04(s)
6.80(m)
—
—
4.26(s)
7.28(s)
7.57(d, 2.5)
—
—
4.16(s)
7.17(s)
7.56(d, 2.5)
—
—
5.20(s)
7.12(s)
7.41(d, 2.5)
—
6.86(d, 8.8)
7.04(d, 2.2)
6.60(d, 2.2)
—
2’
4’
5’
6’
7.04(d, 2.2)
7’
6.82(m)
6.82(m)
6.82(m)
6.82(m)
6.80(m)
7.36(dd, 2.5,
7.36(dd, 2.5,
7.36(dd,
—
8.7)
8.7)
2.5, 8.6)
8’
6.49(d, 2.2)
6.80(m)
6.85(d, 8.7)
6.85(d, 8.7)
6.84(d, 8.6)
—
a
b
7.28(d, 15.5) 7.22(d, 15.5) 7.18(d, 15.5)
7.43(d, 15.5) 7.45(d, 15.5) 7.42(d, 15.5)
6.79(d, 15.5)
7.33(d, 15.5)
7.02(d, 15.7)
7.24(d, 15.4)
7.79(d, 15.6)
7.21(d, 15.5)
7.49(d, 15.5)
7.26(d, 15.7)
7.42(d, 15.4)
7.55(d, 15.6)
2-OMe
3-OMe
4-OMe
5-OMe
6-OMe
3’-OMe
5’-OMe
6’-OMe
7’-OMe
—
—
—
—
—
3.86(s)
—
—
3.84(s)
—
3.87(s)
—
—
3.84(s)
—
—
—
3.84(s)
3.88(s)
—
3.87(s)
—
—
—
—
—
—
—
3.84(s)
—
—
—
—
—
—
—
—
3.84(s)
—
—
—
—
—
—
—
—
3.75(s)
3.82(s)
3.82(s)
—
—
—
—
—
—
—
—
—
3.73(s)
3.72(s)
3.71(s)
—
—
—
—
—
3.77(s)
—
d of 1H (J, Hz)
—
—
—
—
Position
9
10
11
12
13
14
15
16
2
4
4.94(d, 0.7)
7.92(s)
4.95(d, 0.7)
7.91(s)
4.93(d, 0.9)
7.72(s)
4.95(d, 0.9)
7.99(s)
4.95(s)
8.00(s)
4.93(s)
7.96(s)
4.93(s)
7.93(s)
4.94(s)
7.96(s)
(Continues)
Magn. Reson. Chem. (2012)
Copyright © 2012 John Wiley & Sons, Ltd.
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H. Yoon et al.
Table 1. (Continued)
d of 1H (J, Hz)
9
10
2
11
3
12
4
13
5
14
6
15
7
16
8
Position
1
5
7
6.97(d, 3.0)
7.90(dd,
3.0, 8.8)
6.83(d, 8.8)
—
6.97(d, 3.0)
6.90(dd, 3.0,
8.8)
7.10(d, 3.0)
6.88(dd,
3.0, 8.8)
6.82(d, 8.8)
—
6.97(d, 3.0)
6.91(dd,
6.95(d, 2.6)
6.91(dd,
6.93(s)
6.93(s)
6.95(s)
6.92(m)
6.90(m)
6.93(d, 8.6)
3.0, 8.8)
2.6, 8.8)
8
6.83(d, 8.8)
—
6.84(d, 8.8)
—
6.83(d, 8.8)
7.80(d, 8.5)
7.02(d, 8.5)
—
6.84(m)
5.06(s)
6.83(m)
5.11(s)
—
6.85(d, 8.6)
5.11(s)
—
2’
3’
4’
6.64(s)
—
6.74(s)
—
6.32(s)
—
7.11(d, 8.4)
7.45 (ddd, 1.6,
7.5, 8.4)
—
7.07(s)
7.07(s)
7.10(s)
5’
6.63(m)
—
6.32(s)
7.04(d, 7.5)
7.02(d, 8.5)
6.80(m)
7.13(d, 8.4)
6.81(dd,
1.4, 7.9)
6.90(m)
6.98(dd, 1.4,
7.9)
6’
7’
7.87(d, 8.9)
7.47(s)
—
—
7.93(dd, 1.6, 7.5) 7.80(d, 8.5)
—
6.55(d, 8.4)
—
—
—
—
6.81(m)
—
8’
—
—
—
—
—
6.81(m)
6.49(s)
—
a
b
7.62(d, 15.6) 7.60(d, 15.7) 7.72(d, 15.7)
7.88(d, 15.6) 7.93(d, 15.7) 7.98(d, 15.7)
7.75(d, 15.8)
7.67(d, 15.5)
7.15(d, 15.5)
7.05(d, 15.4)
7.14(d, 15.5)
7.35(d, 15.5)
3.75(s)
—
7.94(d, 15.8)
7.58(d, 15.5)
7.33(d, 15.5)
7.33(d, 15.4)
6-OMe
2’-OMe
3’-OMe
4’-OMe
5’-OMe
6’-OMe
7’-OMe
8’-OMe
3.74(s)
3.90(s)
3.74(s)
3.89(s)
3.74(s)
3.93(s)
3.74(s)
3.89(s)
—
3.74(s)
—
3.74(s)
—
3.75(s)
—
—
—
—
—
—
—
—
3.84(s)
3.87(s)
3.82(s)
3.86(s)
—
3.82(s)
—
—
—
—
—
—
—
—
—
—
—
—
—
—
3.93(s)
—
—
3.71(s)
—
—
—
—
—
—
—
—
3.77(s)
—
—
—
—
—
—
3.79(s)
Table 2. The 13C NMR chemical shifts of chromenylchalcones 1–16
d of 13C
Position
1
2
3
4
5
6
7
8
1
131.2
131.4
114.5
163.7
114.5
131.4
—
139.6
106.3
160.7
104.8
160.7
106.3
—
130.5
130.7
113.9
163.1
113.9
130.7
—
128.7
157.7
112.3
133.0
120.5
129.4
—
139.2
112.7
159.5
119.0
130.0
120.7
—
128.8
157.7
112.4
133.0
120.6
129.5
—
139.4
106.3
160.7
105.0
160.7
106.3
—
—
2
63.9
3
131.8
134.1
113.3
154.0
118.5
116.7
148.9
121.6
136.6
106.7
160.7
102.5
160.7
106.7
—
4
5
6
7
8
—
—
—
—
—
—
—
9
—
—
—
—
—
—
—
10
1’
—
—
—
—
—
—
—
—
—
—
—
—
—
—
2’
65.2
64.61
130.6
132.0
112.2
153.9
116.7
116.3
148.2
122.7
121.4
141.0
188.4
—
64.9
64.5
64.7
65.4
64.9
3’
130.9
131.9
112.7
154.4
117.0
116.7
148.6
123.3
121.9
140.5
187.6
—
126.8
131.5
129.2
108.0
161.7
101.3
155.7
115.3
119.8
140.5
187.0
—
130.2
131.4
112.2
153.9
116.5
116.2
148.0
122.6
126.3
139.4
191.8
55.7
134.8
137.8
132.0
109.8
132.6
117.5
155.5
124.9
122.0
147.1
189.2
—
134.7
137.3
132.0
109.8
132.6
117.6
155.6
125.0
127.2
145.6
192.2
55.7
130.9
130.2
130.0
112.8
133.0
117.7
153.4
124.2
122.2
140.5
188.4
—
4’
5’
6’
7’
8’
—
9’
—
10’
a
b
C = O
2-OMe
—
121.2
142.5
186.5
—
(Continues)
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Copyright © 2012 John Wiley & Sons, Ltd.
Magn. Reson. Chem. (2012)

1H and 13C NMR spectral assignments of novel chromenylchalcones
Table 2. (Continued)
d of 13C
Position
1
2
3
4
5
6
7
8
3-OMe
4-OMe
5-OMe
6-OMe
3’-OMe
5’-OMe
6’-OMe
7’-OMe
—
56.1
—
55.5
—
—
55.5
—
—
—
55.3
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
55.5
—
—
—
55.5
—
—
55.5
—
—
—
—
—
55.4
55.5
55.5
—
—
—
—
—
—
—
—
—
—
—
56.0
—
55.4
—
—
55.4
—
d of 13
—
55.4
—
—
C
Position
9
10
64.1
132.2
132.7
113.2
153.9
118.1
116.6
148.8
121.7
114.2
154.2
97.5
152.9
143.0
111.1
—
11
64.2
132.4
131.7
113.7
153.9
117.9
116.4
148.7
121.7
105.0
161.3
91.0
163.2
91.0
161.3
—
12
13
63.9
131.9
133.4
113.3
153.9
118.2
116.6
148.8
121.7
127.3
130.5
114.4
161.2
114.4
130.5
—
14
15
16
2
64.0
132.1
132.9
113.3
153.9
118.0
116.5
148.7
121.7
115.9
159.8
98.2
163.0
106.3
129.5
—
63.9
131.9
133.7
113.4
153.9
118.3
116.6
148.8
121.6
122.9
158.1
111.8
132.2
120.4
128.0
—
63.8
63.9
63.8
3
131.8
133.8
113.2
154.0
118.5
116.6
148.8
121.6
—
131.9
133.4
113.1
153.9
118.3
116.6
148.8
121.6
—
131.8
133.8
113.2
154.0
118.5
116.7
148.8
121.6
—
4
5
6
7
8
9
10
1’
2’
64.7
64.9
65.6
3’
130.4
131.5
112.2
153.9
116.5
116.2
148.1
122.7
120.2
139.2
186.2
55.4
126.5
131.7
129.2
108.1
161.8
101.2
155.7
115.3
118.5
139.7
186.1
55.4
129.7
131.5
120.0
121.5
114.2
147.4
143.1
122.7
120.0
139.4
186.2
55.5
4’
5’
6’
7’
8’
—
—
—
—
—
9’
—
—
—
—
—
10’
—
—
—
—
—
a
b
117.7
137.0
186.5
55.4
55.8
55.5
—
117.4
136.9
186.5
55.5
56.4
55.8
56.5
—
119.0
133.8
187.4
55.5
56.1
55.5
—
120.6
136.7
186.6
55.4
55.7
—
118.3
142.3
186.4
55.4
—
C = O
6-OMe
2’-OMe
4’-OMe
5’-OMe
6’-OMe
7’-OMe
8’-OMe
—
—
—
55.3
—
—
—
—
—
—
—
—
—
56.1
—
—
—
55.4
—
—
—
—
—
—
—
55.4
—
—
—
—
—
—
—
—
55.7
C-4 (133.8 ppm), C-9 (148.8 ppm), H-7 (6.93 ppm), and H-5
(6.95 ppm) were determined. Two undetermined carbons at
129.7 and 131.8 ppm were decided to be C-3’ and C-3, respec-
tively, based on the long-ranged couplings with H-a and H-b,
respectively. The complete assignments of the 1H and 13C
NMR data of chromenylchalcone 16 are listed in Tables 1
and 2, respectively. Similarly, the 1H and 13C NMR data of
15 chromenylchalcones were acquired and are listed in
Tables 1 and 2, respectively.
Chromenylchalcones synthesized here consist of three types:
(E)-3-(2H-chromen-3-yl)-1-methoxyphenylprop-2-en-1-ones (1–7),
(E)-1-(6-methoxy-2H-chromen-3-yl)-3-methoxyphenylprop-2-en-
1-ones (8–13), and (E)-3-(2H-chromen-3-yl)-1-(6-methoxy-2H-
chromen-3-yl)prop-2-en-1-ones (14–16). Chromenylchalcones
2 and 8 contain the same number and position of the
substituents. Although the 13C chemical shifts of C-2 and C-6
of chromenylchalcone 2 are upfield shifted than those of C-2’
and C-6’ of chromenylchalcone 8, the chemical shift of C-4 of
chromenylchalcone 2 is downfield shifted than C-4’ of chrome-
nylchalcone 8. Likewise, chromenylchalcones 1 and 13 contain
the same number and position of the substituents. The 13C
chemical shifts of C-1–C-6 of chromenylchalcone 1 where ben-
zene ring is attached to ketone group are downfield shifted than
those of C-1’–C-6’ of chromenylchalcone 13 where benzene ring
is attached to C-b. This trend is observed in chromenylchalcones
8–13 where 2H-chromene group is attached to ketone group and
in chromenylchalcones 1, 2, and 4 where 2H-chromene group is
attached to C-b. The 13C chemical shifts contained in 2H-chromene
group except C-2 and C-10 of chromenylchalcones 8–13 are down-
field shifted than those of chromenylchalcones 1, 2, and 4. In
Magn. Reson. Chem. (2012)
Copyright © 2012 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/mrc

H. Yoon et al.
dichromenylchalcones 14–16, even the position of methoxy
group is different with each other, the 13C chemical shift of C-2
is upfield shifted than that of C-2’. The 13C chemical shifts of C-a,
C-b, and carbonyl carbon of (E)-3-(2H-chromen-3-yl)-1-phenylprop-
2-en-1-ones (1–7) are downfield shifted than those of (E)-1-(6-
methoxy-2H-chromen-3-yl)-3-phenylprop-2-en-1-ones (8–13).
The reversed trends are observed in the 1H chemical shifts: The
1H chemical shifts of H-a and H-b of chromenylchalcones 1–7
are upfield shifted than those of chromenylchalcones 8–13.
More polysubstituted chromenylchalcones synthesized or isolated
from the natural sources in the future can be identified on the basis
of the NMR data reported here.
Biogreen21 program (RDA, PJ007982). Hyuk Yoon and Seunghyun
Ahn contributed equally to this work.
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wileyonlinelibrary.com/journal/mrc
Copyright © 2012 John Wiley & Sons, Ltd.
Magn. Reson. Chem. (2012)