Frutescone A-G, Tasmanone-Based Meroterpenoids from the aerial parts of Baeckea frutescens

Article abstract of DOI:10.1021/acs.joc.6b02643

Frutescone A-G [(1-6), (+)-7, (-)-7], a new group of naturally occurring tasmanone-based meroterpenoids, were isolated from the aerial parts of Baeckea frutescens L. Compounds 1 and 4 featured a rare carbon skeleton with an unprecedented oxa-spiro[5.8] tetradecadiene ring system, existing as two favored equilibrating conformers in CDCl₃ solution, identified by variable-temperature NMR. The regioselective syntheses of 4-7 were achieved in a concise manner by a biomimetically inspired key hetero-Diels-Alder reaction "on water". Compounds 1, 4, and 5 exhibited moderate cytotoxicities in vitro.

Full text of DOI:10.1021/acs.joc.6b02643

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Article
Frutescone A#G, Tasmanone-Based Meroterpenoids
from the aerial parts of Baeckea frutescens
Ji-Qin Hou, Cui Guo, Jian-Juan Zhao, Qi-Wei He, Bao-Bao Zhang, and Hao Wang
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.6b02643 • Publication Date (Web): 28 Dec 2016
Downloaded from http://pubs.acs.org on December 30, 2016
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Frutescone A‒G, TasmanoneꢀBased Meroterpenoids from the
aerial parts of Baeckea frutescens
†
‡
†
†
†
†
†‡
JiꢀQin Hou, Cui Guo, JianꢀJuan Zhao, QiꢀWei He, BaoꢀBao Zhang, Hao Wang*
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†
State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China
Pharmaceutical University, Nanjing 210009, P. R. China
‡
Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, P. R.
China
ABSTRACT: Frutescone A‒G [(1‒6), (+)ꢀ7, (‒)ꢀ7], a new group of naturally occurring
tasmanoneꢀbased meroterpenoids, were isolated from the aerial part of Baeckea frutescens L.
Compounds 1 and 4 featured a rare carbon skeleton with an unprecedented oxaꢀspiro[5.8]
tetradecadiene ring system, existing as two favoured equilibrating conformers in CDCl3
solution, identified by variableꢀtemperature NMR. The regioselective syntheses of 4‒7 were
achieved in a concise manner by a biomimetically inspired key HeteroꢀDiels–Alder reaction
“
on water”. Compounds 1, 4 and 5 exhibited moderate cytotoxicities in vitro.
INTRODUCTION
Baeckea frutescens L. (Myrtaceae), an aromatic shrub, widely distributed in south China,
southeast Asia, and northern Australia, has long been used in folk medicine for treating
1
fever, rheumatism and snake bites. The aerial parts of B. frutescens as the major herb of
“
Compound Huangsong Lotion”, is used clinically in China for the external treatment of
2
gynecological infectious diseases. Previous phytochemical studies of this plant led to the
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7
isolation of phloroglucinols, sesquiterpenoids, flavonoids,
and chromones with
antiꢀinflammatory, antibacterial and cytotoxic activities.
As parts of our ongoing efforts to investigate the structurally attractive and bioactive
constituents, eight unusual tasmanoneꢀbased meroterpenoids, frutescone A‒G [1‒6, (+)ꢀ7,
(‒)ꢀ7] (Figure 1), were isolated from the aerial part of B. frutescens L. Compounds 1 and 4
featured a rare carbon skeleton with an unprecedented oxaꢀspiro[5.8] tetradecadiene ring
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system, existing as two favoured equilibrating conformers in CDCl solution, identified by
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variableꢀtemperature NMR. Meroterpenoid hybrids are characterized by the connection of
12
phloroglucinol to various terpenoid moieties. In this paper, phytochemical studies of a
series of new naturally occurring tasmanoneꢀcoupled caryophyllene or humulene involving
extensive regioꢀ and stereoselectivity would provide positive clues and evidences for the
biomimetic synthesis of the meroterpenoids. The regioselective syntheses of 4‒7 were
achieved in moderate to low yield in a concise manner using a biomimetic
HeteroꢀDielsꢀAlder (HDA) reaction “on water” (Scheme 2). Furthermore, compounds 1, 4
and 5 exhibited moderate antitumor activities in vitro. Herein, we report the isolation,
structural elucidation, possible biosynthesis, and biological activities of 1‒7.
Figure 1. Structures of compounds 1–7
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RESULTS AND DISCUSSION
Frutescone A (1) was obtained as yellowish crystals. Its molecular formula was
+
determined to be C H O by HRESIMS at m/z 441.3365 [M + H] (calcd for C H O ,
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1
441.3363). H NMR spectra recorded at room temperature presented broad and incomplete
1
3
signals (Figure 2), and most of the C NMR signals were extremely low or invisible (Table
1
). Variableꢀtemperature NMR studies of 1 indicated that two equilibrating conformers, in a
1
ratio of approximately 5: 6 ( H NMR integration), existed in CDCl solution at 242K.
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1
Figure 2. Variableꢀtemperature H NMR spectra of 1 in CDCl
3
1
The H NMR spectrum for the major isomer set 1 (Table 2) showed one olefinic proton
[
(
δ 5.35 (1H, t, J = 7.2 Hz)], six methyl groups [δ 1.23, 1.22, 0.80, 0.89 (each 3H, s); 1.13
H H
3H, d, J = 6.4 Hz), 0.75 (3H, d, J = 6.9 Hz)], two vinyl methyl groups [δ 1.71, 1.69 (each
H
1
3
3H, s)] and a methoxyl group [δ 3.74 (3H, s)]. The C NMR and DEPT spectra displayed
H
2
9 carbon resonances categorized into nine methyls, six methylenes, five methines, and nine
quaternary carbons. The HMBC correlations from Meꢀ9 to Cꢀ4 and Cꢀ6, from OMe to Cꢀ4,
from Meꢀ7 and Meꢀ8 to Cꢀ2 and Cꢀ4, from both Meꢀ12 and Meꢀ13 to Cꢀ10, from Hꢀ10 to
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Cꢀ6, and from Hꢀ11 to Cꢀ1 (Figure 3), established the partial structure of isobutyryl
phloroglucinol moiety (1a). Careful comparison of the NMR data of 1 with those of the
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,12b
literature,
indicated the presence of a caryophyllene moietiy (1b), which was further
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confirmed by HMBC correlations from Meꢀ12′ and Meꢀ13′ to Cꢀ1′ and Cꢀ10′, from Meꢀ14′
1
1
to Cꢀ3′ and Cꢀ5′, and from Hꢀ1′ and H ꢀ6′ to Cꢀ8′, as well as the H− H COSY correlations
2
(
Figure 3). Furthermore, the HMBC correlations from Hꢀ10 and H ꢀ15′ to Cꢀ8′, and from
2
H ꢀ15′ to Cꢀ7′ revealed the substructures 1a and 1b were connected via C –C bond. Thus,
2
10
15′
the planar structure of 1 was therefore determined.
Figure 3. Key 2D NMR correlations and X–ray structure of 1 (30% probability level)
In the NOESY spectrum, the cross peak between H ꢀ3′ and Hꢀ5′, and between H ꢀ6′ to
2
2
4
′,5′
Meꢀ14′, indicated an Eꢀgeometry for the double bond (ꢁ ). Due to the flexible
nineꢀmembered ring of caryophyllene, four conformational isomers existed with different
8
dispositions of the exocyclic methylene and olefinic methyl groups. ββ (set 1) and βα (set
2
), as being the two lowestꢀenergy conformations were detected in 1, similar to the
1
2b
caryophylleneꢀbased meroterpenoid isolated from Myrtus communis.
The 2D NMR
correlations found in NMR signals of set 2 were almost the same as those recorded in set 1.
1
1
With the aid of H– H COSY, HSQC, HMBC and NOESY experiments recorded at 242K,
1
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all the H and C NMR signals of 1 were assigned as shown in Table 2.
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Table 1. H and C NMR Data of 1 and 4 in CDCl (298K)
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a
a
1
4
No
δH (J, in Hz)
δ
‒
δH (J, in Hz)
δC
C
c
1
2
3
108.6
188.5
117.4
171.3
43.1
200.3
49.1
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11
12
13
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19
20
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58
59
60
4
5
6
167.7
111.9
‒
c
169.2
10.2
7
8
1.25, s
1.24, s
1.75, s
25.8
‒
1.86, s
‒
c
b
c
‒
9
10
11
9.9
1.19, s
23.3
c
b
c
2.71, brs
‒
‒
‒
‒
‒
‒
b
c
b
c
‒
‒
‒
b
1
1
2
3
21.0
0.84, d (6.8)
21.0
b
c
b
c
‒
‒
‒
‒
‒
‒
‒
‒
‒
‒
‒
‒
‒
c
c
1
2
3
′
′
′
2.49, brs
2.48, brs
b
c
b
c
‒
‒
‒
‒
b
c
b
c
c
c
4′
5′
c
c
5.35, brs
.11, brs
5.35, brs
5.10, brs
5
b
c
b
c
6′
7′
8′
9′
‒
‒
‒
‒
‒
‒
‒
‒
‒
‒
‒
‒
b
c
b
c
c
c
b
c
c
‒
‒
1.34, m
b
c
b
c
10′
11′
‒
‒
‒
32.7
29.9
24.4
16.0
32.3
b
b
c
12′
13′
14′
15′
‒
‒
‒
0.91, s
1.71, s
0.90, s
1.70, s
25.0
c
‒
‒
b
c
b
c
‒
‒
‒
OMe
3.75, s1
61.9
3.81, s
61.7
a
13
b
c
Recorded at 600 ( H) and 150 ( C) MHz. Signals unassigned. Signals invisible.
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1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
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Table 2. H and C NMR Data of 1 and 4 in CDCl (242K)
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ab
ab
1
4
No.
set 1 (ββ)
set 2 (βα)
set 1 (ββ)
δH ( J, in Hz)
set 2 (βα)
δH ( J, in Hz)
δH ( J, in Hz)
δC
δH ( J, in Hz)
δC
δC
δC
1
2
3
106.8
200.5
48.8
107.3
108.1
108.1
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
200.4
48.7
167.5
111.9
166.4
25.9
22.7
10.0
32.2
32.4
22.5
21.0
53.3
30.3
188.7
117.2
171.3
42.9
169.4
10.3
24.7
23.0
31.8
31.8
20.8
20.9
54.5
30.5
188.8
117.2
171.2
42.9
168.7
10.2
24.8
23.1
31.7
32.6
21.4
22.3
52.4
29.7
4
5
6
7
167.2
112.1
166.4
25.7
1.24, s
1.21, s
1.74, s
1.23, s
1.22, s
1.84, s
1.25, s
1.18, s
1.85, s
1.23, s
1.15, s
8
22.8
9
10.1
1.71, s
10
2.64, dt (9.0, 4.2) 32.3
2.70, dd (10.4, 6.7)
1.60
2.64, dq (7.6, 4.2)
2.05, m
0.81, d (6.4)
0.97, d (6.8)
2.45
2.70, dd (10.4, 6.2)
1.59, m
1.12, d (6.4)
0.77, d (6.8)
2.13
1
1
2.05
1.00, d (6.4)
0.80, d (6.9)
2.50
32.2
20.8
20.9
54.9
29.6
1
1
2
3
1.13, d (6.4)
0.75, d (6.9)
2.17
1′
2′a
2′b
3′a
3′b
1.60
1.47
2.46
1.70
1.95
1.51
2.07
1.95
2.01
1.52
2.45
1.60
1.71
1.43
2.05
1.95
36.8
39.9
39.8
37.3
4
5
6
′
′
′
133.2
125.6
23.7
137.8
120.0
22.3
133.2
125.6
23.7
137.7
119.9
22.4
5.07, d (12.1)
2.30
5.35, t (7.2)
2.40
5.06, d (12.1)
2.26
5.34, t (8.1)
2.32
7
7
′a
′b
2.05
1.72
40.9
2.01
1.90
43.2
2.05
1.75
40.3
1.93
1.75
42.8
8
′
85.8
47.8
35.9
31.1
29.9
24.7
16.2
24.6
87.9
46.4
35.1
31.1
29.7
23.1
16.2
23.9
83.7
47.7
36.6
30.9
29.9
24.9
16.2
24.7
85.3
46.2
35.2
32.1
29.7
22.8
16.2
23.9
9′
1.35
1.28
1.57
2.50
1.37, t (9.4)
1.22
1.61
2.45
1
1
0′
1′
12′
13′
14′
15′
0.84, s
0.88, s
1.70, s
1.71
0.80, s
0.89, s
1.69, s
1.90
0.85, s
0.87, s
1.68, s
1.71
0.80, s
0.88, s
1.69, s
1.89
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OMe
3.74, s
62.1
3.74, s
62.1
3.79, s
62.0
3.79, s
62.0
a
1
13
b
Recorded at 600 ( H) and 150 ( C) MHz. Overlapped signals without designating multiplicity.
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1
1
2
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2
2
2
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A single crystal of 1 (Figure 3, CCDC 1495749) was obtained from methanol, and
Xꢀray crystallographic analysis was carried out by using the anomalous dispersion of CuKα
radiation. The crystallized conformer was the preferable ββ conformer with the
C ‒C ‒C ‒C torsional angle of 152.76°. The absolute configuration of 1 was determined
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
3
′
4′
5′
6′
as 10R, 1′R, 8′R, 9′S by refinement of the Flack parameter [0.06 (5)].
Frutescone B (2) was obtained as yellowish crystals. It shared the same molecular
formula of C H O as 1 based on the HRESIMS data. A comparison of the NMR data of 2
2
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3
(Table 3) with those of 1, suggested the presence of the same isobutyryl phloroglucinol
moiety (2a), which was further confirmed by the HMBC correlations (Figure 4). The two
spin systems (H ꢀ3′/H ꢀ2′/Hꢀ1′/Hꢀ9′/H ꢀ10′, and H ꢀ7′/H ꢀ6′/Hꢀ5′/Hꢀ10/Hꢀ11/Meꢀ12 and
2
2
2
2
2
1
1
Meꢀ13) in the Hꢀ H COSY spectrum, together with the HMBC correlations from H ꢀ15′ to
2
Cꢀ7′ and Cꢀ9′, from both Hꢀ1′ to Cꢀ8′, from Meꢀ12′ and Meꢀ13′ to Cꢀ1′ and Cꢀ10′, from
H ꢀ2′ and H ꢀ6′ to Cꢀ4′, and from H ꢀ3′ and Meꢀ14′ to Cꢀ5′ indicated the presence of a
2
2
2
caryophyllene unit (2b). Furthermore, the HMBC correlations from Hꢀ10 to Cꢀ4′ and Cꢀ6′,
and from Hꢀ5′ to Cꢀ11 confirmed that substructure 2a was coupled with 2b through C ‒C
5′
1
0
bond.
1
1
Figure 4. Hꢀ H COSY, HMBC and ROESY correlations of 2‒4
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The relative stereochemistry of 2 could be elucidated by a ROESY experiment. The
NOE correlations of Meꢀ14′/Hꢀ10; Hꢀ5′/Meꢀ12 and Meꢀ13 indicated that Meꢀ14′ and Hꢀ10
were βꢀoriented, while Hꢀ5′ was αꢀoriented.
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52
53
54
55
56
57
58
59
60
Interestingly, HPLC analyses of 2 using different chiral columns showed one sharp signal,
but the crystal exhibited twinning (Figure 5, CCDC 1495761), including two identical units.
The final refinement on the CuKα data resulted in the Flack parameter 0.05 (4), allowing
unambiguous assignment of the absolute structure of 2 (10S, 1′R, 4′R, 5′S, 9′S).
Figure 5. Xꢀray crystallographic twinning structures of 2 (30% probability level)
2 and 3 shared the same planar structures, as deduced by the detail analysis of
HRESIMS and NMR spectroscopic data. The relative stereochemistry of 3 was assigned by
the ROESY spectrum (Figure 4). The correlations of Meꢀ14′/Hꢀ11, together with the
absence of Meꢀ14′/Hꢀ10, and Hꢀ5′/Hꢀ11, Meꢀ12 revealed α orientations of Hꢀ10 and Hꢀ5′,
and β orientation of Meꢀ14′. In addition, the experimental CD curves of 2 and 3 were almost
reverse, suggesting the chiral difference of Cꢀ10 near the chromophore moiety. The
stereochemistry of 3 were designated as 10R, 1′R, 4′R, 5′S, 9′S by Xꢀray crystallographic
analysis (Figure 6, CCDC 1495762).
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1
1
1
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1
1
1
1
1
2
2
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2
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2
2
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2
3
3
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3
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3
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3
4
4
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4
4
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5
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5
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5
5
5
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0
1
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5
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7
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9
0
1
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5
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7
8
9
0
1
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5
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7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 6. Xꢀray crystallographic structures of 3 and 4 (30% probability level)
Frutescone D (4) was obtained as colorless needle crystals with the molecular formula
of C H O established by the HRESIMS data. Interestly, the variableꢀtemperature NMR
2
9
44
3
data of 4 were very similar with those of 1 (Table 2), except for the different ratio of the
existing two atropisomers [approximately 6: 5 of ββ (set 1): βα (set 2)], which indicated that
4
shared the same oxaꢀspiro[5.8] tetradecadiene skeleton. Moreover, the UV absorption
maxima at 204, 248 and 298 nm in 4 were dramatically distinguished from those of 1 (217,
39 nm) (see the Supporting Information), implying a different phloroglucinol moiety (4a),
3
which was further confirmed by the HMBC correlations from Meꢀ7 to Cꢀ2 and Cꢀ4, from
OMe to Cꢀ4, from both Meꢀ8 and Meꢀ9 to Cꢀ4 and Cꢀ6, from Meꢀ12 and Meꢀ13 to Cꢀ10,
from Hꢀ10 to Cꢀ6, and from Hꢀ11 to Cꢀ1 (Figure 4). The linkage of C ‒C between 4a and
1
0
15′
4
b was supported by the HMBC cross peaks from Hꢀ10 to Cꢀ8′, and from Hꢀ15′ to Cꢀ7′.
The relative stereochemistry of 4 was deduced as shown in Figure 1 by a single crystal
Xꢀray MoKα diffraction study (Figure 6, CCDC 1495774). Combining with the comparison
of experimental CD curve (Figure 7) with those of 5 and 6 allowed the absolute
configuration of 4 as 10R, 1′R, 8′R, 9′S.
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1
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Table 3. H and C NMR Data of 2, 3 and 5ꢀ7 in CDCl
3
a
a
a
b
a
2
3
5
6
7
No.
δH ( J, in Hz)
δC
δH ( J, in Hz)
δC
δH ( J, in Hz)
δC
δH ( J, in Hz)
δC
δH ( J, in Hz)
δC
1
2
3
4
5
6
7
8
9
111.8
199.8
49.6
167.6
112.3
167.4
25.2
23.4
9.7
110.4
200.2
49.1
167.9
111.7
165.8
25.8
23.6
9.9
114.8
187.8
118.0
172.1
42.5
169.7
10.0
23.6
23.9
40.4
31.9
20.8
19.3
54.2
21.8
112.6
188.2
117.4
171.9
42.7
168.9
10.1
24.4
23.5
35.8
26.0
26.8
19.7
57.1
23.7
115.2
188.0
117.8
172.2
42.7
170.6
23.8
23.7
10.2
41.5
35.5
18.4
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
1.26, s
1.23, s
1.83, s
2.36, mc
2.02, m
1.26, s
1.25, s
1.81, s
1.88, s
1.32, s
1.23, s
1.89, s
1.30, s
1.28, s
1.34, s
1.24, s
1.90, s
10
11
12
13
1′
2′a
40.7
32.2
2.68, t (4.2)
2.02, m
36.0
26.6
26.8
19.9
57.0
23.7
2.35, d (7.1)
2.70, mc
2.67, t (3.7)
c
c
c
2.05, m
2.03, m
2.10, m
0.88, d (7.1) 20.5
0.80, d (7.1) 20.0
1.15, d (6.9)
0.65, d (6.9)
0.89, d (7.2)
0.75, d (7.2)
1.17, d (6.8)
0.64, d (7.0)
0.75, d (6.6)
0.91, d (7.0)
22.7
143.3
121.1
c
c
c
c
c
2.03, mc
1.75, mc
1.42, m
54.3
22.2
1.60, m
2.10, m
1.56, mc
5.19, mc
c
c
1.54, m
1.83, m
1.59, mc
5.19, m
c
c
2
′b
′a
′b
1.39, m
1.42, m
1.33, m
c
c
c
c
3
2.02, mc
39.3
2.06, m
44.1
2.05, m
39.2
2.03, m
44.5
2.51, mc
2.28, m
45.0
c
c
3
1.84, m
1.55, m
1.90, m
1.47, m
4
5
6
′
′
′
82.7
38.9
36.3
35.5
85.6
39.3
25.2
35.6
82.7
38.4
36.2
35.5
84.2
39.6
25.1
35.7
84.6
40.6
33.4
36.4
c
c
c
c
c
2.10, mc
1.77, m
c
2.14, m
1.78, m
c
2.30, mc
1.53, m
1.76, m
1.56, m
1.71‒1.81, m
2.41, m
1.33, mc
c
7
′a
2.44, mc
2.40, m
2.45, m
2.12, m
c
c
7
′b
2.01, m
2.16, m
2.03, m
2.16, m
8
9
′
′
152.8
42.3
35.5
151.4
41.1
36.8
152.8
42.2
36.0
151.3
41.7
36.6
136.1
124.0
41.6
c
c
2.40, m
2.45, m
2.40, m
2.43, m
5.10, t (8.5)
c
c
1
1
0′a
0′b
1.62, t (9.5)
1.69, m
1.76, t (10.2)
1.70, mc
2.10, mc
c
1.58, m
1.58, m
1.90, m
1
1
1
1
1
1′
2′
3′
4′
5′
33.8
30.7
22.6
21.6
111.2
34.4
29.9
21.9
23.3
111.1
33.7
30.7
22.6
21.3
111.2
34.4
29.9
21.9
23.1
110.9
38.5
25.9
28.5
21.2
18.1
1.03, s
1.01, s
0.99, s
0.93, s
0.96, s
1.32, s
1.02, s
0.99, s
0.99, s
0.93, s
0.96, s
1.29, s
1.11, s
1.09, s
1.02, s
1.62, s
4.94, brs
4.90, brs
4.94, brs
4.88, brs
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3
3
3
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4
4
4
4
4
4
4
4
4
4
4
.87, brs
4.88, brs
OMe
3.78, s 1
61.8
3.76, s
61.8
3.83, s
61.8
3.83, s
61.8
3.85, s
61.8
a
13
b
1
13
c
Recorded at 300 ( H) and 75 ( C) MHz. Recorded at 500 ( H) and 125 ( C) MHz. Overlapped signals without designating multiplicity.
0
1
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4
5
6
7
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9
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Figure 7. Experimental CD spectra of 1−6
Frutescone E (5) and frutescone F (6) were isolated as a pair of Cꢀ10 epimers of
tasmanoneꢀcoupled caryophyllene meroterpenoids characterized with the almost reverse
experimental CD spectra (Figure 7). The structure and relative configurations of 5 and 6
1
1
were elucidated by unambiguous analyses of H− H COSY, HMBC and NOESY spectra
(Figure 8), as well as comparison of NMR data with those of 2‒4. The absolute
configurations were determined to be 10S, 1′R, 4′R, 5′S, 9′S (5) and 10R, 1′R, 4′R, 5′S, 9′S
(
6) by ECD calculation using TDDFT method at the B3LYP/6ꢀ31G(d) level (Figure 9).
1
1
Figure 8. Hꢀ H COSY, HMBC and ROESY correlations of 5‒7
Frutescone G (7) consists of a pair of enantiomers (see the Supporting Information),
with the molecular formula of C H O determined by the HRESIMS data. Comparison of
2
9
44
3
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6
the NMR data of 7 (Table 3) with those of 4‒6 suggested the presence of substructure 7a.
Three spin systems (H ꢀ7′/H ꢀ6′/Hꢀ5′/Hꢀ10/Hꢀ11/Meꢀ12 and Meꢀ13, Hꢀ1′/Hꢀ2′/H ꢀ3′, and
2
2
2
1
1
Hꢀ9′/H ꢀ10′) in the H− H COSY spectrum, and the HMBC correlations from Meꢀ12′ and
2
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Meꢀ13′ to Cꢀ1′ and Cꢀ10′, from Meꢀ15′ to Cꢀ7′ and Cꢀ9′, and from Hꢀ3′ and Meꢀ14′ to Cꢀ5′,
1
2b
led to the construction of a humulene unit (7b) (Figure 8). The HMBC correlations from
Hꢀ10 to Cꢀ4′ and Cꢀ6′, and from Hꢀ5′ to Cꢀ11 indicated that 7a and 7b were connected via
C ‒C bond.
10
5′
The NOESY correlations of Hꢀ1′/H ꢀ3′, H ꢀ7′/Hꢀ9′, and Meꢀ15′/H ꢀ10′ suggested E
2
2
2
1′,2′
8′,9′
geometry of the double bonds (ꢁ , ꢁ ). Meꢀ14′ had obvious crossꢀpeaks with Hꢀ11 and
Meꢀ12, but had no NOE correlation with Hꢀ10. Combined with the absence of NOE
correlation from Hꢀ5′ to Hꢀ11 and Meꢀ12, it was suggested that Meꢀ14′, Hꢀ11 and Meꢀ12
were β orientations, while Hꢀ10 and Hꢀ5′ were α orientations, which were found being the
1
2b,12d
same with those of 3 and 6, as reported in the literature
. Thus, the relative
stereochemistry of 7 was determined as in Figure 1. The chiral stereochemistries of (+)ꢀ7
and (‒)ꢀ7 were designated as 10S, 4′S, 5′R and 10R, 4′R, 5′S, respectively, by the calculated
ECD spectra (Figure 9).
Figure 9. Calculated and experimental ECD spectra of 5 and (‒)ꢀ7
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Scheme 1. Plausible Biosynthetic Pathways of 1−7
The plausible biosynthetic pathway of triketone (flavesone, leptospermone)ꢀcoupled
1
2b,12c
sesquiterpenoids has been previously proposed.
Herein, a different biogenetic
9
precursor, tasmanone (8), is believed to be involved in the biosynthesis of 1‒7. As
illustrated in Scheme 1, the key intermediate 8, βꢀcaryophyllene (9), and αꢀhumulene (10)
4
were reported as the major constituents of B. frutescens essential oil. Selective reduction
and dehydration of 8 to generate the active intermediate A1, which could undergo a HDA
reaction with 9 or 10 to afford 1‒7 in a regioꢀ and stereoselective manner.
Further exploration on the biosynthetic origin led to the regioselective syntheses of 4‒7
initiated with commercially available phloroglucinol (11), 9 or 10 as substrates, as presented
1
0
in Scheme 2. First, acetylation of 11 would give acetyl phloroglucinol (12) , trimethylation
10c
of 12 would provide 13 , which could undergo acid induced retroꢀClaisen condensation
and Knoevenagel condensation to afford the active intermediate 15. HeteroꢀDielsꢀAlder
reaction in toluene/water (3:1) of 15 with 9 or 10, respectively, was followed by
methylation. Notably, the HDA reaction carried out by stirring a toluene solution of the
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1
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5
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5
5
5
5
5
5
5
6
11
substrates “on water”, proceeded at a considerably higher rate and yield than in toluene
alone or solventꢀfree conditions. After twoꢀstep sequences, regiospecific cyclization adducts
4
‒7 were isolated in 60% (4:5:6 = 1.1:1.0:1.1) or 13.5% (7) yield, while the products 1‒3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
were extremely trace due to unfavorable regioselectivity. The acceleration of HDA reaction
“on water” was presumably ascribed to hydrophobic collapse and/or an hydrogenꢀbond
1
1
mediated stabilization of the transition state. Consequently, the NMR spectra and chiral
HPLC analyses of synthetic compounds 4‒7 were compared to those of natural frutescone
D‒G (4‒7) isolated from B. frutescens and found being identical.
Scheme 2. Regioselective Synthesis of 4‒7 via HeteroꢀDiels–Alder Reaction “On water”
The isolates were evaluated for cytotoxicities against three human cancer cell lines
Cacoꢀ2, A549 and HepG2 (Table 4). Compounds 1 and 4 exhibited moderate cytotoxic
activities against Cacoꢀ2 with IC50 values of 8.08 ꢂM and 10.20 ꢂM, respectively.
Compound 5 showed activities against Cacoꢀ2 and A549 with IC value of 7.96 ꢂM and
5
0
12.14 ꢂM.
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Table 4. Cytotoxicity Data of 1‒7 (IC , µM)
5
0
Compound
Cacoꢀ2
A549
HepG2
> 50
1
8.08 ± 2.79
20.07 ± 5.77
2
23.25 ± 3.91 41.33 ± 4.42
14.83 ± 5.97 27.74 ± 4.76
10.20 ± 3.44 26.25 ± 6.10
> 50
3
> 50
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
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29
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31
32
33
34
35
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37
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54
55
56
57
58
59
60
4
> 50
5
7.96 ± 2.56
12.14 ± 5.55
> 50
6
16.51 ± 2.52 39.02 ± 6.02
14.31 ± 4.07 25.71 ± 5.89
> 50
7
> 50
a
doxorubicin
6.03 ± 4.31
doxorubicin was used as a positive control.
6.31 ± 2.89
8.23 ± 2.64
a
In order to verify that the reported compounds 1−7 are indeed natural products, the fresh
aerial parts of B. frutescens were percolated with methanol at room temperature, or
extracted with CH Cl directly by ultrasonator, respectively. The two crude extracts were
2
2
analyzed by HPLCꢀQ/TOFꢀMS or LCꢀMSD Trap methods, respectively (see the Supporting
Information). Compounds 1−7 were detected in above two different crude extracts by
n
comparsion of the HPLC retention times, MS spectra, and UV absorptions with those of
isolates. Thus, compounds 1−7 are proved to be natural occurring products in B. frutescens,
not artifacts produced during the isolation and purification procedure.
CONCLUSION
Frutescone A‒G (1‒7), a new group of naturally occurring unusual tasmanoneꢀbased
meroterpenoids were firstly isolated from B. frutescens L. Biogenetically, compounds 1‒7
1
2
possessed extensive regioꢀ and stereoselective [4+2] cycloaddition architectures, which
largely enriched the chemodiversity of phloroglucinol−terpene derivatives. Compounds 4‒7
as the regioselectively favored [4+2]ꢀcycloaddition adducts were achieved by a biomimetic
HDA reaction “on water”, which not only enabled the structural assignments, but also
established the superior role of water in aspects of rate, yield and selectivity, and could
provide valuable inspiration for ecoꢀfriendly organic synthesis in aqueous suspension. The
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1
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5
6
broaden applicability of this strategy for construction of bioactive tasmanoneꢀbased
phloroglucinols to diverse terpenoids are currently under research in our laboratory.
EXPERIMENTAL SECTION
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
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2
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8
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0
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2
3
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5
6
7
8
9
0
General Experimental Procedures
Column chromatography was performed using silica gel (100–200 and 200–300 mesh),
MCI gel (CHP20P, 75−150 ꢂm), Sephadex LHꢀ20 and ODS (50 ꢂm). Optical rotation was
measured on a polarimeter. UV spectra were recoreded on a UV/vis spectrophotometer
using MeOH as the solvent. IR spectra were carried on a FTꢀIR spectrometer with KBr
disks. CD spectra were obtained on a spectropolarimeter. 1D, 2D NMR spectra were
1
recorded in CDCl on 600, 500 and 300 MHz ( H) NMR spectrometers with TMS as
3
1
1
internal standard. All NMR assignments were based on H− H COSY, HSQC, and HMBC
spectroscopic data. Diffraction data were collected on diffractometers using CuKα and
MoKα radiation. Preparative HPLC and chiral HPLC separations were performed using C8
column (250 × 20 mm, 5 ꢂm) and Chiral ODꢀRH column (250 × 10 mm, 5 ꢂm),
respectively. Both HRESIMS and LCꢀMS analyses was performed on an analytical HPLC
system coupled with a Q/TOF mass spectrometer equipped with an ESI source in positive
mode.
Plant Material
The aerial parts of Baeckea frutescens (Myrtaceae) were collected from Guangxi
province of P. R. China in October of 2014, and authenticated by Prof. MinꢀJian Qin
(Department of Medicinal Plants, China Pharmaceutical University, Nanjing). A voucher
specimen (No. BF201410) was deposited in the Department of Natural Medicinal
Chemistry, China Pharmaceutical University.
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Extraction and Isolation
The dry aerial parts of B. frutescens (18 kg) were extracted with 95% EtOH (100 L)
under reflux (3 × 4 h) at 83 ºC. The combined extracts were concentrated under reduced
pressure to afford a dark green residue extract (2.0 kg), which was suspended in water (3 L)
and successively extracted with petroleum ether (4 × 3 L), chloroform (3 × 3 L) and
nꢀbutanol (4 × 3 L).
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The petroleum ether extract (500 g) was subjected to silica gel column chromatography
with PEꢀEtOAc (100:0→40:60, v/v) as eluent to afford eight fractions (Fr. A‒H). Fr. C (104
g) was further separated into five fractions (Fr. C1‒C5) on a silica gel column (PEꢀEtOAc,
100: 0→30:70, v/v) according to their TLC profiles. Fr. C2 (10.5 g) was subjected to a MCI
gel column with a gradient mixture of MeOHꢀH O (60:40→100:0, v/v ) as eluent to give Fr.
2
C2.1‒6. Then, Fr. C2.4 (310 mg) was then run on an ODS column (MeCNꢀH O,
2
60:40→100:0, v/v), to afford Fr. C2.4.1‒5. Then, Fr. C2.4.4 (183 mg) was applied onto
Sephadex LHꢀ20 (CHCl ꢀMeOH, 50:50) to yield Fr. C2.4.4.1‒3. Then, Fr. C2.4.4.3 was
3
further purified by recycled preparative HPLC (MeCNꢀH O, 90:10, 12 mL/min) to afford 1
2
(7 mg), 3 (10 mg) and 4 (24 mg). Fr. D (73 g) was chromatographed on a silica gel column
with PEꢀEtOAc (100:0→40:60, v/v) as eluent to yield six fractions (Fr. D1‒D6). Fr. D4 was
further subjected to an ODS column using a gradient elution of MeOHꢀH O (65:35→100:0,
2
v/v), Sephadex LHꢀ20 gel column (CHCl ꢀMeOH, 50:50), and recycled preparative HPLC
3
(
MeCNꢀH O, 85:15, 12 mL/min), respectively, to yield 5 (31 mg), 7 (10 mg), 2 (6 mg) and
2
6
(27 mg). Compound 7 was further separated into enantiomers (+)ꢀ7 (1.0 mg, t 13.1 min)
R
and (‒)ꢀ7 (1.0 mg, t 15.9 min) by chiral HPLC using MeCNꢀH O (85:15, 4 mL/min) as the
R
2
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Frutescone A (1). Yellowish crystals (MeOH), mp 198‒200 ºC; [α]D ‒129.0 (c 0.02,
1
13
MeOH); H and C NMR data see Tables 1 and 2; IR (KBr)ν 2951, 2921, 2849, 1657,
max
−1
1
648, 1624, 1557, 1468, 1388, 1128 cm ; UV (MeOH) λ (log ε) 217 (4.45), 339 (3.79)
max
0
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0
nm; CD (MeOH) λmax (ꢁε) 231 (‒0.6), 299 (+8.3), 342 (‒10.0) nm; ESIMS m/z 441 [M +
+
+
H] ; HRESIMS m/z 441.3365 [M + H] (calcd C H O 441.3363).
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D
0
Frutescone B (2). Yellowish crystals (MeOH), mp 202‒204 ºC; [α] +28.6 (c 0.02,
1
13
MeOH); H and C NMR data see Table 3; IR (KBr) ν 2962, 2930, 2870, 1662, 1636,
max
−
1
1
570, 1459, 1384, 1128 cm ; UV (MeOH) λ (log ε) 202 (3.94), 348 (2.87) nm; CD
max
+
(MeOH): λmax (ꢁε) 228 (+8.1), 303 (+2.4), 350 (‒1.5) nm; ESIMS m/z 441 [M + H] ;
+
HRESIMS m/z 441.3367 [M + H] (calcd C H O 441.3363).
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2
D
0
Frutescone C (3). Yellowish crystals (MeOH), mp 193‒197 ºC; [α] +74.7 (c 0.03,
1
13
MeOH); H and C NMR data see Table 3; IR (KBr) ν 2962, 2926, 2873, 1660, 1628,
max
−
1
1568, 1397, 1385, 1130 cm ; UV (MeOH) λ (log ε) 204 (4.13), 342 (3.38) nm; CD
max
+
(
MeOH) λmax (ꢁε) 235 (‒6.2), 301 (‒4.9), 349 (+1.8) nm; ESIMS m/z 441 [M + H] ;
+
HRESIMS m/z 441.3359 [M + H] (calcd C H O 441.3363).
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D
0
Frutescone D (4). Colorless needle crystals (MeOH); mp 175‒177 ºC; [α] +110.0 (c 0.02,
1
13
MeOH); H and C NMR data see Tables 1 and 2; IR (KBr) ν 2950, 2935, 2869, 1664,
max
−
1
1
610, 1400, 1363, 1130 cm ; UV (MeOH) λ (log ε) 204 (4.41), 248 (4.20), 298 (3.90)
max
nm; CD (MeOH) λmax (ꢁε) 211 (‒42.3), 248 (+22.2), 290 (+10.0) nm; ESIMS m/z 441 [M +
+
+
H] ; HRESIMS m/z 441.3357 [M + H] (calcd C H O 441.3363).
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13
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D
Frutescone E (5). Light yellow oil; [α] +96.7 (c 0.1, MeOH); H and C NMR data see
−
1
Table 3; IR (KBr) νmax 2955, 2962, 2869, 1670, 1622, 1465, 1400, 1110 cm ; UV
(
MeOH) λmax (log ε) 203 (4.45), 250 (4.16), 296 (3.81) nm; CD (MeOH) λmax (ꢁε) 207
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(
‒10.5), 251 (+21.8), 292 (+10.5) nm; ESIMS m/z 441 [M + H] ; HRESIMS m/z 441.3363
+
[
M + H] (calcd C H O 441.3363).
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Frutescone F (6). Light yellow oil; [α] ‒51.6 (c 0.1, MeOH); H and C NMR data see
D
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1
Table 3; IR (KBr) νmax 2956, 2931, 1747, 1662, 1616, 1469, 1389, 1130 cm ; UV
(
MeOH) λmax (log ε) 203 (4.38), 249 (4.20), 298 (3.87) nm; CD (MeOH) λmax (ꢁε) 207
+
(
+26.1), 250 (‒7.2), 294 (‒6.8) nm; ESIMS m/z 441 [M + H] ; HRESIMS m/z 441.3363 [M
+
+ H] (calcd C H O 441.3363).
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20
D
20
D
Frutescone G (7). Light yellow oil; [α] +180.0 (c 0.1, MeOH) for (+)ꢀ7, [α] ‒160.0 (c
1
13
0.1, MeOH) for (‒)ꢀ7; H and C NMR data see Table 3; IR (KBr)ν 2958, 2928, 1664,
max
−1
1
624, 1458, 1384, 1121 cm ; UV (MeOH) λ (log ε) 204 (4.06), 252 (3.85), 297 (3.46)
max
nm; CD (MeOH) λmax (ꢁε) 207 (‒9.7), 251 (+17.1), 294 (+9.6) nm for (+)ꢀ7; CD (MeOH)
+
λmax (ꢁε) 207 (+9.7), 251 (‒16.4), 294 (‒9.5) nm for (‒)ꢀ7; ESIMS m/z 441 [M + H] ;
+
HRESIMS m/z 441.3366 [M + H] (calcd C H O 441.3363).
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Xꢀray Crystallographic Analyses
Crystallographic data of 1
C H O , M = 440.64, monoclinic, space group P21 (no. 4), a = 9.11100(10) Å, b =
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3
9.88290(10) Å, c = 14.9752(2) Å, α = 90°, β = 100.1270(10)°, γ = 90°, V = 1327.41(3) Å , Z
−1
3
=
2, T = 291(2) K, ꢀ(CuKα) = 0.592 mm , D = 1.102 g/cm , 11309 reflections measured
calc
Θ
(
14.994° ≤ 2 ≤ 139.392°), 4688 unique (R = 0.0152, R
= 0.0172) which were used in
int
sigma
all calculations. The final R was 0.0355 (I > 2σ(I)) and wR was 0.1040 (all data). The
1
2
2
Goodnessꢀofꢀfit on F was 1.060. Flack parameter = 0.06 (5). (CCDC1495749).
Crystallographic data of 2
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C H O , M = 440.00, monoclinic, space group P21 (no. 4), a = 8.78970(10) Å, b =
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4
2.3070(2) Å, c = 26.0231(3) Å, α = 90°, β = 93.9320(10)°, γ = 90°, V = 2808.42(6) Å , Z =
−
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, T = 288(2) K, ꢀ(CuKα) = 0.562 mm , D = 1.118 g/cm , 26234 reflections measured
calc
0
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7
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9
0
Θ
(
7.95° ≤ 2 ≤ 141.348°), 10061 unique (R = 0.0163, R
= 0.0177) which were used in
int
sigma
all calculations. The final R was 0.0402 (I > 2σ(I)) and wR was 0.1269 (all data). The
1
2
2
Goodnessꢀofꢀfit on F was 1.031. Flack parameter = 0.05 (4). (CCDC 1495761)
Crystallographic data of 3
C H O , M = 440.64, orthorhombic, space group P212121 (no. 19), a = 8.41900(10) Å, b
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3
=
17.21920(10) Å, c = 18.20720(10) Å, α = 90°, β = 90°, γ = 90°, V = 2639.47(4) Å , Z = 4,
−1
3
T = 290(2) K, ꢀ(CuKα) = 0.538 mm , D
= 1.109 g/cm , 23773 reflections measured
calc
Θ
(7.066° ≤ 2 ≤ 142.604°), 5034 unique (R = 0.0194, R
= 0.0142) which were used in
int
sigma
all calculations. The final R was 0.0307 (I > 2σ(I)) and wR was 0.0862 (all data). The
1
2
2
Goodnessꢀofꢀfit on F was 1.039. Flack parameter = ‒0.05 (5). (CCDC 1495762)
Crystallographic data of 4
C H O , M =440.64, monoclinic, space group P21 (no. 4), a = 10.928(2) Å, b = 6.4320
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3
(13) Å, c = 19.345 (4) Å, α = 90°, β = 95.38(3)°, γ = 90°, V = 1353.85(5) Å , Z = 2, T =
−
1
3
2
98(2) K, ꢀ(MoKα) = 0.068 mm , D = 1.08093 g/cm , The R (reflections) was 0.0742
calc
2
(
1121) and wR (reflections) was 0.0978 (2724). The Goodnessꢀofꢀfit on F was 1.001.
2
(CCDC 1495774)
Synthetic Experimental Part
1
0
Acylphloroglucinol (12)
To a stirred suspension of phloroglucinol (11) (10.0 g, 0.079 mol) in a mixture of
CH Cl (80 mL) and nitromethane (80 mL), was added aluminium trichloride (42.3 g, 0.317
2
2
mol, 4 equiv) and the mixture was stirred at room temperature for 30 min. To this dark
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suspension acetyl chloride (5.7 mL, 0.079 mol, 1 equiv) was added slowly by syringe and
refluxed for 3 h untile completion of the reaction checked by TLC. Thereafter, the mixture
was cooled down to room temperature and poured into iceꢀwater followed by evaporation of
the volatiles under reduced pressure. Then, the water phase was extracted by EtOAc (3 ×
160 mL). The combined organic layers were washed with saturated NaCl solution, dried
over Na SO , filtered and concentrated in vacuo. Purification of the residue by silica gel
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4
chromatography (PEꢀEtOAc, 2:1) provided acylphloroglucinol (12) (8.1 g, 61%) as
1
yellowish crystals. H NMR (300 MHz, DMSOꢀd ): δ 12.20 (2H, br s, OH), 10.33 (1H, brs,
6
H
13
OH), 5.80 (2H, s, Ar), 2.54 (3H, s, Me); C NMR (75 MHz, DMSOꢀd ): δ 202.4 (C=O),
6
C
164.7 (Cꢀ4), 164.3 (Cꢀ2, Cꢀ6), 104.0 (Cꢀ1), 94.6 (Cꢀ3, Cꢀ5), 32.3 (COMe). ESIMS m/z 169
+
‒
[M + H] , 167 [M ‒ H] .
ꢀacetylꢀ3, 5ꢀdihydroxyꢀ4, 6, 6ꢀtrimethylcyclohexaꢀ2, 4ꢀdienone (13)
To a solution of acylphloroglucinol (12) (5 g, 29.8 mmol) and tertꢀBuOK (12.4 g, 110
10c
2
mmol, 3.7 equiv) in anhydrous MeOH (70 mL) was added methyliodide (5.6 mL, 89.6
mmol, 3 equiv). The resulting mixture was heated to reflux for 7 h and then cooled down to
room temperature. The mixture was concentrated under reduced pressure and the residue
redissolved in water and acidified with 1 M HCl aqueous solution, before it was extracted
with EtOAc (3 × 150 mL). The combined organic layers were washed with water, dried
over Na SO and concentrated in vacuo. The residue was chromatographed on silica gel
2
4
colunm, eluted with PEꢀEtOAc (9:1 to 4:1) to provide 13 (3.56 g, 57%). Light yellow
1
powder, H NMR (300 MHz, DMSOꢀd ): δ 18.94 (1H, brs, chelatedꢀOH), 2.49 [3H, s,
6
H
1
3
C(O)Me], 1.79 (3H, s, Me), 1.30 (6H, s, Me × 2); C NMR (75 MHz, DMSOꢀd ): δ 199.2
6
C
(C=O), 196.0 (C=O), 188.7 (CꢀOH), 176.1 (CꢀOH), 105.0, 101.8, 48.2 [C(Me) ], 27.7
2
+
‒
[
C(O)Me], 24.3 (Me × 2), 7.2 (Me). ESIMS m/z 211 [M + H] , 209 [M ‒ H] .
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, 5ꢀdihydroxyꢀ4, 6, 6ꢀtrimethylcyclohexaꢀ2, 4ꢀdienone (14)
A suspension of 13 (200 mg, 0.95 mol) in 3 M HCl (20 mL) was refluxed at 110 ºC for 2
h until the starting material had disappeared (TLC control). Thereafter, the mixture was
cooled down to room temperature and extracted with EtOAc (3 × 20 mL). The combined
organic layers were washed twice with water, dried over Na SO , filtered and concentrated
0
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in vacuo. The residue was passed through silica gel column using PEꢀEtOAc (2:1) as eluent
to provide 14 (144 mg, 90%) as light yellow oil. 14 was prone to isomerization, so it was
used immediately for the next step.
(Z/E)ꢀ5ꢀhydroxyꢀ4,6,6ꢀtrimethylꢀ2ꢀ(2ꢀmethylpropylidene)cyclohexꢀ4ꢀeneꢀ1,3ꢀdione (15)
To a suspension of 14 (200 mg, 1.19 mmol) in CH Cl (3.6 mL) was added
2
2
isobutyraldehyde (164 ꢂL, 1.8 mmol, 1.5 equiv) followed by dropwise addition of
piperidine (68 ꢂL, 2.4 mol, 2 equiv) at room temperature. After being stirred for 15 min, the
reaction mixture was quenched with 1 M HCl saturated NH Cl solution (2 mL) and stirred
4
vigorously for 1 h. This mixture was extracted with CH Cl (3 × 5 mL). The combined
2
2
organic layers were dried over Na SO , filtered, and concentrated in vacuo. The residue was
2
4
passed through a short flash silica gel column using CH Cl as eluent to afford 15 (79 mg,
2
2
30%) as yellow oil. 15 was rather unstable and used immediately for the next step.
Frutescone D‒F (4‒6)
A solution of 15 (60 mg, 0.27 mmol) and βꢀcaryophyllene (184 ꢂL, 0.81 mmol, 3 equiv)
in tolueneꢀH O (3:1, 7.2 mL) and was refluxed at 110 ºC for 4 h under a nitrogen
2
atmosphere. The reaction mixture was concentrated to dryness in vacuo and dissolved in
anhydrous EtOAcꢀMeOH (5:1, 3 mL). Then a solution of TMSCHN in diethyl ether (0.5
2
mL, 1 mmol, 2 M in hexane) was added slowly at room temperature under nitrogen
atmosphere, and the mixture was stirred for 2 h. The mixture was concentrated, and the
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residue was subjected to silica gel column chromatography with PEꢀEtOAc (100:0 to 95:5,
v/v) as eluent to yield four fractions (A‒D). Then the fraction B was purified by recycled
preparative HPLC (MeCNꢀH O, 80:20, 12 mL/min) to afford 4 (23.4 mg, 19.7%), 5 (22.0
2
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11
12
13
14
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mg, 18.5%) and 6 (24.5 mg, 20.6%). The synthetic compounds 4‒6 were identical by TLC,
NMR, and chiral HPLC comparison in with the natural products 4‒6. (see the Supporting
1
Information) Compound 4, Light yellow oil, H NMR (500 MHz, CDCl , 298K): δ 1.87
3
H
(3H, s, Meꢀ7), 1.27 (3H, s, Meꢀ8), 1.20 (3H, s, Meꢀ9), 2.73 (1H, brs, Hꢀ10), 0.84 (3H, d, J =
7.1 Hz, Meꢀ12), 2.47 (1H, brs, Hꢀ1′), 5.34 (1H, brs, Hꢀ5′), 5.13 (1H, brs, Hꢀ5′), 1.37 (1H, m,
Hꢀ9′), 0.87 (3H, s, Meꢀ12′), 0.91 (3H, s, Meꢀ13′), 1.71 (3H, s, Meꢀ14′), 3.81 (3H, s, OMe);
1
3
C NMR (125 MHz, CDCl , 298K): δ 108.7 (Cꢀ1), 188.5 (Cꢀ2), 117.4 (Cꢀ3), 171.3 (Cꢀ4),
3
C
43.1 (Cꢀ5), 169.3 (Cꢀ6), 10.1 (Cꢀ7), 23.3 (Cꢀ9), 21.0 (Cꢀ12), 54.8 (Cꢀ1′), 125.9 (Cꢀ5′), 32.3
1
(
Cꢀ11′), 30.0 (Cꢀ12′), 25.1 (Cꢀ13′), 61.8 (OMe). Compound 5, Light yellow oil, H NMR
(
500 MHz, CDCl ): δ 1.87 (3H, s, Meꢀ7), 1.32 (3H, s, Meꢀ8), 1.23 (3H, s, Meꢀ9), 2.35 (1H,
3
H
dd, J = 7.0, 2.4 Hz, Hꢀ10), 2.10‒1.95 (1H, m, Hꢀ11), 0.89 (3H, d, J = 7.1 Hz, Meꢀ12), 0.75
3H, d, J = 7.1 Hz, Meꢀ13), 2.15‒2.05 (1H, m, Hꢀ1′), 1.86‒1.75 (1H, m, Hꢀ2′a), 1.40 (1H, m,
(
Hꢀ2′b), 2.10‒1.95 (1H, m, Hꢀ3′a), 1.89 (1H, m, Hꢀ3′b), 2.14 (1H, m, Hꢀ5′), 1.64‒1.49 (2H,
m, Hꢀ6′), 2.50‒2.37 (1H, m, Hꢀ7′a), 2.10‒1.95 (1H, m, Hꢀ7′b), 2.47‒2.36 (1H, m, Hꢀ9′),
1.80‒1.65 (2H, m, Hꢀ10′), 1.02 (3H, s, Meꢀ12′), 0.99 (3H, s, Meꢀ13′), 0.99 (3H, s, Meꢀ14′),
1
3
4.94 (1H, brs, Hꢀ15′a), 4.87 (1H, brs, Hꢀ15′b), 3.83 (3H, s, OMe); C NMR (125 MHz,
CDCl ): δ 114.8 (Cꢀ1), 187.8 (Cꢀ2), 118.0 (Cꢀ3), 172.1 (Cꢀ4), 42.5 (Cꢀ5), 169.8 (Cꢀ6), 10.0
3
C
(
(
(
(
Cꢀ7), 23.6 (Cꢀ8), 23.9 (Cꢀ9), 40.4 (Cꢀ10), 31.9 (Cꢀ11), 20.8 (Cꢀ12), 19.3 (Cꢀ13), 54.2
Cꢀ1′), 21.8 (Cꢀ2′), 39.2 (Cꢀ3′), 82.6 (Cꢀ4′), 38.5 (Cꢀ5′), 36.2 (Cꢀ6′), 35.5 (Cꢀ7′), 152.8
Cꢀ8′), 42.2 (Cꢀ9′), 36.0 (Cꢀ10′), 33.7 (Cꢀ11′), 30.7 (Cꢀ12′), 22.6 (Cꢀ13′), 21.3 (Cꢀ14′), 111.2
1
Cꢀ15′), 61.8 (OMe). Compound 6, Light yellow oil, H NMR (300 MHz, CDCl ): δ 1.90
3
H
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3H, s, Meꢀ7), 1.31 (3H, s, Meꢀ8), 1.29 (3H, s, Meꢀ9), 2.70 (1H, m, Hꢀ10), 2.08‒2.00 (1H,
m, Hꢀ11), 1.17 (3H, d, J = 6.9 Hz, Meꢀ12), 0.64 (3H, d, J = 6.9 Hz, Meꢀ13), 1.60‒1.53 (1H,
m, Hꢀ1′), 1.63‒1.56 (1H, m, Hꢀ2′a), 1.36 (1H, m, Hꢀ2′b), 2.08‒2.00 (1H, m, Hꢀ3′a), 1.48
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(1H, m, Hꢀ3′b), 1.79 (1H, m, Hꢀ5′), 1.82‒1.70 (2H, m, Hꢀ6′), 2.48‒2.39 (2H, m, Hꢀ7′),
2.48‒2.39 (1H, m, Hꢀ9′), 1.70 (1H, m, Hꢀ10′a), 1.63‒1.56 (1H, m, Hꢀ10′b), 0.94 (3H, s,
Meꢀ12′), 0.97 (3H, s, Meꢀ13′), 1.30 (3H, s, Meꢀ14′), 4.89 (2H, brs, Hꢀ15′), 3.84 (3H, s,
1
3
OMe); C NMR (75 MHz, CDCl ) δ 112.7 (Cꢀ1), 188.3 (Cꢀ2), 117.5 (Cꢀ3), 171.9 (Cꢀ4),
3
42.7 (Cꢀ5), 168.9 (Cꢀ6), 10.1 (Cꢀ7), 24.4 (Cꢀ8), 23.5 (Cꢀ9), 35.8 (Cꢀ10), 26.0 (Cꢀ11), 26.8
(
Cꢀ12), 19.7 (Cꢀ13), 57.1 (Cꢀ1′), 23.7 (Cꢀ2′), 44.5 (Cꢀ3′), 84.2 (Cꢀ4′), 39.7 (Cꢀ5′), 25.1
Cꢀ6′), 35.8 (Cꢀ7′), 151.4 (Cꢀ8′), 41.8 (Cꢀ9′), 36.6 (Cꢀ10′), 34.4 (Cꢀ11′), 29.9 (Cꢀ12′), 21.9
(
(Cꢀ13′), 23.1 (Cꢀ14′), 110.9 (Cꢀ15′), 61.8 (OMe).
±)ꢀFrutescone G (7)
(
A solution of 15 (50 mg, 0.23 mmol) and αꢀhumulene (10) (155 ꢂL, 0.68 mmol, 3 equiv) in
tolueneꢀH O (3:1, 6 mL) and was refluxed at 110 ºC for 4 h under a nitrogen atmosphere.
2
The reaction mixture was concentrated to dryness in vacuo and redissolved in anhydrous
EtOAcꢀMeOH (5:1, 2.5 mL). Then a solution of TMSCHN in diethyl ether (0.35 mL, 0.7
2
mmol, 2 M in hexane) was added slowly at room temperature under nitrogen atmosphere,
and the mixture was stirred for 2 h. The mixture was concentrated in vacuo, and the residue
was subjected to silica gel column chromatography with PEꢀEtOAc (100:0 to 95:5, v/v) as
eluent to yield four fractions (A‒F). Then the fraction D was purified by preparative HPLC
(MeCNꢀH O, 85:15, 12 mL/min) to afford (±)ꢀ7 (13.3 mg, 13.5%). The synthetic racemic
2
mixture (±)ꢀ7 was identical by TLC, NMR, and chiral HPLC in comparison with the natural
product (±)ꢀfrutescone G (7). (see the Supporting Information) Compound 7, Light yellow
1
oil, H NMR (300 MHz, CDCl ): δ 1.34 (3H, s, Meꢀ7), 1.24 (3H, s, Meꢀ8), 1.90 (3H, s,
3
H
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Meꢀ9), 2.67 (1H, t, J = 4.0 Hz, Hꢀ10), 2.17‒2.00 (1H, m, Hꢀ11), 0.75 (3H, d, J = 6.8 Hz,
Meꢀ12), 0.92 (3H, d, J = 6.8 Hz, Meꢀ13), 5.18 (1H, m, Hꢀ1′), 5.18 (1H, m, Hꢀ2′), 2.54‒2.49
(
1H, m, Hꢀ3′a), 2.30‒2.23 (1H, m, Hꢀ3′b), 2.35‒2.25 (1H, m, Hꢀ5′), 1.37‒1.25 (2H, m, Hꢀ6′),
.17‒2.00 (2H, m, Hꢀ7′), 5.10 (1H, m, Hꢀ9′), 2.17‒2.00 (1H, m, Hꢀ10′a), 1.90 (1H, m,
Hꢀ10′b), 1.10 (3H, s, Meꢀ12′), 1.09 (3H, s, Meꢀ13′), 1.01 (3H, s, Meꢀ14′), 1.62 (3H, s,
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1
3
Meꢀ15′), 3.85 (3H, s, OMe); C NMR (75 MHz, CDCl ): δ 115.2 (Cꢀ1), 188.0 (Cꢀ2),
3
C
117.9 (Cꢀ3), 172.1 (Cꢀ4), 42.7 (Cꢀ5), 170.6 (Cꢀ6), 23.8 (Cꢀ7), 23.7 (Cꢀ8), 10.2 (Cꢀ9), 41.5
(Cꢀ10), 35.5 (Cꢀ11), 18.4 (Cꢀ12), 22.8 (Cꢀ13), 143.3 (Cꢀ1′), 121.1 (Cꢀ2′), 45.0 (Cꢀ3′), 84.6
(
Cꢀ4′), 40.6 (Cꢀ5′), 33.4 (Cꢀ6′), 36.4 (Cꢀ7′), 136.1 (Cꢀ8′), 124.0 (Cꢀ9′), 41.6 (Cꢀ10′), 38.5
Cꢀ11′), 25.9 (Cꢀ12′), 28.6 (Cꢀ13′), 21.2 (Cꢀ14′), 18.1 (Cꢀ15′), 61.8 (OMe).
(
Cell viability assay
The effects of the isolates on cells viability were measured by the MTT reduction assay.
5
Cacoꢀ2, A549 and HepG2 human cancer cells were seeded onto 96ꢀwell plates (1 × 10
cells/mL in 100 ꢂL of medium), respectively, and incubated for 24 h at 37 °C in a
humidified atmosphere of 5% CO . Each tumor cell line was exposed to the test compounds
2
at various concentrations in triplicate for 24 h, with doxorubicin as positive control. Then 20
ꢂL MTT solution (5 mg/mL) was added to each well and incubated continuously for
another 4 h at 37 °C. After the supernatant was removed, the formed formazan crystals were
dissolved in DMSO (150 µL/well) by constant shaking for 10 min. The absorbance was
measured on an Infinite M200 Pro (Tecan) microplate reader at a test wavelength of 490 nm.
IC was determined as the concentration that inhibited cell growth by 50% using the MTT
50
assay. The data represent the mean of three experiments performed in triplicate and are
expressed as means ± SD.
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ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the ACS Publications website.
ECD calculations, MS and NMR spectra for 1−7 (PDF).
Crystallographic data for 1 (CIF)
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Crystallographic data for 2 (CIF)
Crystallographic data for 3 (CIF)
Crystallographic data for 4 (CIF)
AUTHOR INFORMATION
Corresponding Author
*Eꢀmail: wanghao@cpu.edu.cn (H. Wang)
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENT
This work was financially supported by the National Natural Science Foundation of China
(No. 81573309), the Open Project Program of Jiangsu Key Laboratory of Drug Screening
(JKLD2015KFꢀ01), the Project Funded by the Priority Academic Program Development of
Jiangsu Higher Education Institutions (PAPD), and the Research and and Innovation Project
for College Graduates of Jiangsu Province 2015 (No. KYLX15_0661).
REFERENCES
(
1) Cheung, S. C.; Li, N. H. Chinese Medicinal Herbs of Hong Kong. Vol. 1; Commercial Press: Hong
Kong, 1991, p 96.
2) Wen, W. ꢀP. China Pharmacist 2004, 7, 599‒601.
(
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(
3) (a) Fujimoto, Y.; Usui, S.; Makino, M.; Sumatra, M. Phytochemistry 1996, 41, 923‒925. (b) Nisa, K.;
Ito, T.; Matsui, T.; Kodama, T.; Morita, H. Phytochem. Lett. 2016, 15, 42‒45. (c) Nisa, K.; Ito, T.;
Kodama, T.; Tanaka, M.; Okamoto, Y.; Asakawa, Y.; Imagawa, H; Morita, H. Fitoterapia 2016, 109,
2
36‒240.
4) (a) Tsui, W. Y.; Brown, G. D. J. Nat. Prod. 1996, 59, 1084‒1086. (b) Dai, D. N.; Thang, T. D.;
Olayiwola, T. O.; Ogunwande, I. A. Int. Res. J. Pure. Appl. Chem. 2015, 8, 26‒32.
5) (a) Jia, B. ꢀX.; Zhou, Y. ꢀX.; Chen, X. ꢀQ.; Wang, X. ꢀB.; Yang, J.; Lai, M. ꢀX.; Wang, Q. Magn.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(
(
Reson. Chem. 2011, 49, 757‒761. (b) Jia, B. ꢀX.; Zeng, X. ꢀL.; Ren, F. ꢀX.; Jia, L.; Chen, X. ꢀQ.; Yang, J.;
Liu, H. ꢀM.; Wang, Q. Food Chem. 2014, 155, 31‒37.
(6) Makino, M.; Fujimoto, Y. Phytochemistry 1999, 50, 273‒277.
(7) (a) Tsui I. Y.; Brown, G. D. Phytochemistry 1996, 43, 871‒876. (b) Satake, T.; Kamiya, K.; Saiki, Y.
Hama, H.; Fujimoto, Y.; Endang, H.; Umar, M. Phytochemistry 1999, 50, 303‒306. (c) Gray, C. A.;
Kaye, P. T.; Nchinda, A. T. J. Nat. Prod. 2003, 66, 1144‒1146.
(
(
(
8) Hübner, M.; Rissom, B.; Fitjer, L. Helv. Chim. Acta. 1997, 80, 1972‒1982.
9) Bick, I. R. C.; Horn, D. H. S. Aust. J. Chem. 1965, 18, 1405‒1410.
10) (a) Müller, H.; Paul, M.; Hartmann, D.; Huch, V.; Blaesius, D.; Koeberle, A.; Werz, O.; Jauch, J.
Angew. Chem. Int . Ed. 2010, 49, 2045‒2049. (b) Morkunas, M.; Dube, L.; Götz, F.; Maier, M. E.
Tetrahedron 2013, 69, 8559‒8563. (c) Nguyen, N. T.; Pham, V. C.; Litaudon, M.; Guéritte, F.; Bodo, B.;
Nguyen, V. T.; Nguyen, V. H. Tetrahedron 2009, 65, 7171‒7176.
(
11) Narayan, S.; Muldoon, J.; Finn, M. G.; Fokin, V. V.; Kolb, H. C.; Sharpless, K. B. Angew. Chem. Int .
Ed. 2005, 44, 3275‒3279.
12) (a) Yang, X. ꢀW.; Li, Y. ꢀP.; Su, J.; Ma, W. ꢀG.; Xu, G. Org. Lett. 2016, 18, 1876−1879. (b) Liu, C.;
(
Ang, S.; Huang, X. ꢀJ.; Tian, H. ꢀY.; Deng, Y. ꢀY.; Zhang, D. ꢀM.; Wang, Y.; Ye, W. ꢀC.; Wang, L. Org.
Lett. 2016, 18, 4004–4007. (c) Zhang, Y. ꢀL.; Chen, C.; Wang, X. ꢀB.; Wu, L.; Yang, M. ꢀH.; Luo, J.;
Zhang, C.; Sun, H. ꢀB.; Luo, J. ꢀG.; Kong, L. ꢀY. Org. Lett. 2016, 18, 4068‒4071. (d) Gao, Y.; Wang, G.
ꢀQ.; Wei, K.; Hai, P.; Wang, F.; Liu, J. –K. Org. Lett. 2012, 14, 5936−5939. (e) Fu, H. ꢀZ.; Luo, Y. ꢀM.; Li,
C. ꢀJ.; Yang, J. ꢀZ.; Zhang, D. ꢀM. Org. Lett. 2010, 12, 656−659. (f) Shao, M.; Wang, Y.; Liu, Z.; Zhang,
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