Total synthesis of dysidavarone A

Article abstract of DOI:10.1016/j.tet.2016.05.073

Dysidavarone A is a sesquiterpene isolated from the South China Sea sponge Dysidea avara and was reported that it showed significant anticancer activities. Because the compound has unique ‘dysidavarane’ carbon skeleton and potent biological activity, a se

Full text of DOI:10.1016/j.tet.2016.05.073

Accepted Manuscript
Total synthesis of dysidavarone A
Chunhui Yu, Xiaoguang Zhang, Jinghua Zhang, Zhengwu Shen
PII:
S0040-4020(16)30490-2
10.1016/j.tet.2016.05.073
TET 27800
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 15 April 2016
Revised Date: 24 May 2016
Accepted Date: 30 May 2016
Please cite this article as: Yu C, Zhang X, Zhang J, Shen Z, Total synthesis of dysidavarone A,
Tetrahedron (2016), doi: 10.1016/j.tet.2016.05.073.
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ACCEPTED MANUSCRIPT
Total Synthesis of Dysidavarone A
#
, ‡
#, ‡
#,†
*,†
Chunhui Yu , Xiaoguang Zhang , Jinghua Zhang and Zhengwu Shen
†
School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, People’s Republic of China
‡
Shanghai University of Traditional Chinese Medicine, Shanghai 201203, People’s Republic of China
ABSTRACT. Dysidavarone A is a sesquiterpene isolated from the South China Sea sponge Dysidea
avara and was reported that it showed significant anticancer activities. Because the compound has unique
“dysidavarane” carbon skeleton and potent biological activity, a seven-step stereoselective synthesis of
dysidavarone A was developed. The key steps of the synthesis involved stereoselective
reductive-alkylation, intramolecular α-arylation and double bond migration reaction. The
anti-proliferation activities of Dysidavarone A against human kidney carcinoma cell lines 786-O and
human prostate cancer cell lines PC-3 were also assessed.
During the past three decades, many natural products containing quinone or hydroquinone skeleton
1
,2
have been isolated from marine sponges. Most of those compounds were reported to have interesting
3
,4
biological activities including antibacterial, antitumor, antifungal and anti-inflammatory activities.
Dysidavarone A is one of the quinone sesquiterpene isolated from the South China Sea sponge Dysidea
*
To whom correspondence should be addressed. Tel:+86-21-64457997. E-mail:
Jeff_shen_1999@yahoo.com.
#
These authors contributed equally to the paper.
1

ACCEPTED MANUSCRIPT
avara. The compound was reported to have potent antiproliferation activities against four human cancer
5
cell lines. Due to its unique three-dimensional architecture of tetracyclic core and promising biological
activity, dysidavarone A has become thetarget of synthetic laboratories. So far, there are two groups who
6
have completed the total synthesis of dysidavarone A. Herein, we report our studies of the total synthesis
of dysidavarone A from a commercial available starting material 2-methyl cyclohexanone-1, 3-dione.
6
a
Although our synthetic strategy was similar to the Menche’s synthesis , the use of less steric hindered 3,
-diethoxyl benzyl bromide 22 as the alkylation agent, not only improved the yield of reductive alkylation
5
reaction, but also circumvented the deprotection step through direct oxidization of the phenol moiety into
quinone (2). Hence the overall yield of the synthesis was significantly improved. In addition, the
antiproliferation activities of dysidavarone A and its derivatives (Figure 1) against human kidney
carcinoma cells 786-O and human prostate cancer cells PC-3 were also presented.
.
Figure 1. Dysidavarone A and its derivatives
RESULTS AND DISCUSSION
Our initial retrosynthetic analysis of dysidavarone A is outlined in Scheme 1. The two double bonds of
Dysidavarone A can be easily obtained from the Wittig olefination of 4, 8-diketone of compound 5 with
2

ACCEPTED MANUSCRIPT
the subsequent double bond isomerization. The quinone moiety of the dysidavarone A can be derived from
the aromatic ring of compound 5. The compound 5 was envisioned to be synthesized through the alpha
arylation reaction from compound 6. The strategy used for appending the aromatic moiety to the bicyclic
7
sesquiterpene skeleton is well documented and is based upon the stereoselective reductive alkylating of
an enone derivative 8 with a substituted benzyl bromide. The Wieland-Miescher ketone analogue 8 could
8
be readily obtained from 2-methylcyclohexane-1, 3-dione in three steps.
O
OEt
OEt
H
H
OEt
OEt
O
O
O
Dysidavarone A (1)
5
OEt
O
H
OEt
O
OEt
OEt
Br
O
+
O
Br
O
Br
O
OEt
OEt
6
7
8
Scheme 1. Retrosynthetic Analysis of Dysidavarone A
Based on above retrosynthetic analysis, our initial synthetic approach started from the preparation of
compound 7 and compound 8. As illustrated in Scheme 2, the Wieland-Miescher ketone analogue 8 was
prepared smoothly from commercially available 2-methyl cyclohexanone-1,3-dione 9 in three steps with
8
9
3.2% ee according to a previously reported procedure. The substituted benzyl bromide 7 was obtained
from orcinol in five steps with 61.8% overall yield. The key reactions used for the synthesis of compound
7
involving Vilsmeier-Haack reaction, Baeyer-Villiger oxidation and double-bromination with NBS.
3

ACCEPTED MANUSCRIPT
O
O
TsOH, MEG
DCM, rt, 48 h
O
L-phenylalanine
(+)-CSA/DMF
rt to 70 C
85%
ethyl vinyl ketone
O
O
TEA, EtOAC
o
o
7
0 C, 10 h
O
O
O
94%
90%
O
O
9
10
11
8
POCl3 EtO
HO
Et2(SO4)2 EtO
K CO , Acetone
H2O2-KHSO4
EtO
o
2
3
DMF, 100 C, 1 h
MeOH
rt, 4 h
1
8 h
OH
OEt
OEt O
14
OH
97%
91%
90%
OEt
15
12
13
OEt
OEt
OEt
Et (SO )
2
4 2
3.2 eq NBS
EtO
EtO
Br
K CO , Acetone
2
3
hv, CCl , 6 h
4
10 h
Br
9
6%
81%
OEt
1
6
7
Scheme 2. The Synthesis of Compound 7 and 8
Having the compound 7 and compound 8 in hand, as illustrated in Scheme 3, we began to explore the
reductive alkylation reaction and try to synthesize the key intermediate 6. However, despite of various
9
reaction conditions screened, the yield of the reaction is very poor, only small amounts of compound 6
was obtained (8%). Although, the compound 6 can be converted into 18 in 72% yield, the exceptional low
yield of 6 prompted us to focus our investigation on the reductive alkylation reaction. The stepwise
approach of this reaction was examined, the stereoselective Birch reduction of compound 7 went on
smoothly and gave the ketone 17 as a single isomer in 89% yield. However, the subsequent alkylation
reaction was not successful even under vigorous reaction condition.
4

ACCEPTED MANUSCRIPT
o
o
Li, NH , THF, -78 C to -33 C, 7, 8%
3
H
7
O Li, NH ,THF
O
O
H
OEt
OEt
Pd(OAc)2, PPh3
3
o
o
OEt
o
THF, 100 C, 24 h
-
78 C to -33 C
O
various conditions
72%
O
89%
O
O
Br
O
O
8
17
6
OEt
OEt
OEt
H
H
O
OEt
3
OEt
N HCl, THF
O
2
h
O
88%
O
H
OEt
O
1
8
5
OEt
OEt
O
H
OEt
OEt
O
19
Dysidavarone A
Scheme 3. The Initiate Synthetic Approach
We anticipated that the low efficiency of the alkylation is due to the steric hindrance of the
7
ortho-substitutions on the aromatic ring of the benzyl bromide. Hence, the less steric hindrance alkylating
agent, 3, 5-diethoxyl benzyl bromide 22 was selected as the alkylation agent for the reaction (Scheme 4).
The 3, 5-diethoxyl benzyl bromide 22 was readily synthesized from compound 20 in two steps
quantitatively. The reaction between compound 8 and compound 22 went on smoothly and the key
intermediate 23 was obtained in 82% yield under standard reductive-alkylation condition. Since
compound 8 has 5β-Me configuration (Scheme 5), the initial stereoselective hydride SN2 addition at
position 10 and the sequent alkylation occurred from the less hindered α-face of the anion intermediate to
form compound 23 stereoselectively (dr>19:1). The stereochemistry of 23 was confirmed by
two-dimensional NMR spectroscopic methods. The dibromo-substituted compound 24 could also be used
as the alkylation agent in the reductive alkylation reaction and the compound 25 was obtained in 60%
yield. These results indicated that the size of the substituent at the ortho position of benzyl bromide is the
5

ACCEPTED MANUSCRIPT
main factor which affect the yield of this reaction. The bromination of compound 23 with NBS in
methylene chloride gave the compound 25 as the only product in 92% yield.
8
EtO
Et (SO )
OEt
EtO
OEt
H
HO
OH
O
3
Li, NH ,THF
2
4 2
PBr , Py
3
OEt
o
o
O
K CO , Acetone
DCM, rt, 4 h
8%
-78 C to -33 C
2
3
O
1
8 h
8
2%
9
9
7%
OH
21
Br
22
OH
OEt
20
23
NBS
NBS
o
o
DCM, 0 C, 1 h
92%
DCM, 0 C, 1 h
91%
8
OEt
Li, NH ,THF
O
H
Br
3
OEt
o
o
O
Br
-78 C to -33 C
60%
O
OEt
Br
OEt
24
25
H
O
OEt
H
O
2
x-phos, Pd (dba)3
3N HCl, THF
OEt
Ph PCH Br
3
3
O
tBuONa, Diox
00 C, 4 h
tBuOK, toulene
2
h
o
1
40 h
O
OEt
88%
90%
O
92%
O
OEt
2
6
27
O
H
H
H
p-TsOH
OEt
OEt
CrO3
AcOH, H
OEt
2
O
AcOH, rt, 12 h
o
0
C, 0.5 h
8%
6
92%
O
OEt
O
28
2
Dysidavarone A
Scheme 4. The Total Synthesis of Dysidavarone A
The palladium catalyzed intra-molecular cyclization of compound 25 gave the tetracyclic core of the
dysidavarone A in a stereospecific manner in 88% yield. The dioxolane protecting group of compound 26
was removed in the presence of 3N hydrochloric acid in 92% yield and a subsequent Wittig reaction
1
0
formed two exocyclic double bonds in one step in 90% of yield. The key step for accomplishing the
synthesis is to convert the aromatic ring into quinone moiety without affecting the allylic positions of two
exocyclic double bonds. Due to the substitution pattern on the aromatic ring of compound 28, compound 2
was expected as the only product of oxidation. Various oxidants including CAN, salcomine and CrO
3
6

ACCEPTED MANUSCRIPT
were screened. Finally, the CrO
3
was selected as which successfully accomplished the desired oxidation
1
1
and gave compound 2 in 68% yield. The final step for the synthesis of dysidavarone A is to convert the
exocyclic double bond at position 4 of compound 2 into endo-double bond. Again, various acids and
.
Lewis acids were investigated which includes RuCl , RhCl 3H O, PTSA, TFA and HCl. Eventually,
3
3
2
PTSA in AcOH was found to be the best conditions for such double bond migrate reaction, and compound
1
2
2
was successfully converted into dysidavarone A in 90% yield.
.
OH
-
.
O
.
O
Protonation
Li, NH3
8
+
e
O
O
O
O
O
O
8a
8b
8c
X
R
H
-
OH
O
2
3
+
e
O
O
O
O
8d
8e
Scheme 5. The Stereochemistry of Reductive Alkylation
The synthetic dysidavarone A obtained is identical in all respects (NMR, IR, and MS) to natural
dysidavarone A. The total synthesis of dysidavarone A described above requires seven steps from readily
available diketone 8 and proceeds in 34% overall yield. Upon we were finishing this synthesis, Menche’s
group published the first total synthesis of dysidavarone A with a similar strategy. Compared with
Menche’s synthesis, this synthesis used a less steric hindered 3, 5-diethoxyl benzyl bromide 22 as the
alkylation agents, not only improved the yield of reductive alkylation, but also omitted the deprotection
step through direct oxidize the phenol moiety into quinone. The methyl derivative 4 was also obtained
according the same procedure from compound 8 in seven steps in 33% overall yield (Scheme 6).
7

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O
H
O
H
OMe
Br
8
NBS
OMe
OMe
O
o
O
Li, NH ,THF
DCM, 0 C, 1 h
3
o
o
O
H
O
-
78 C to -33 C
Br
OMe
83%
91%
OMe
OMe
29
30
3
8
1
5%
Pd(OAc) , PPh3
2
o
THF, 100 C, 24 h
H
3N HCl, THF
H
OMe Ph
PCH
Br
3
OMe
OMe
3
tBuOK, toulene
0 h, 92%
O
O
2
h, 93%
4
O
O
OMe
O
OMe
OMe
3
4
33
32
o
CrO3
0 C, 0.5 h
67%
AcOH, H O
2
O
O
O
H
H
OMe
p-TsOH
OMe
AcOH, rt, 12 h
9
0%
O
3
4
Scheme 6. The synthesis of methyl derivative of Dysidavarone A
The compounds synthesized above were assessed for the anti-proliferation activities against renal
cancer cell lines 786-O and prostate cancer cell lines PC-3. The GI of the compounds were listed in
5
0
Table 1. All these four compounds tested showed moderate anti-proliferation activities.
Conclusions
In conclusion, dysidavarone A was successfully synthesized in seven steps starting from known
building block 8. Compared with Menche’s approach, this synthesis used a less steric hindered 3,
5
-diethoxyl benzyl bromide 22 as the alkylation agents, not only improved the yield of reductive
alkylation, but also omitted the deprotection step through direct oxidize the phenole moiety into quinone,
thus the overall yield of the synthesis was significantly improved.
8

ACCEPTED MANUSCRIPT
Table 1 The Anti-proliferation Activities of dysidavarone A and Its Derivatives
a
b
7
86-O GI50
PC-3 GI
50
Compound
(
µM)
3.71
6.12
6.37
3.58
<0.02
(µM)
6.71
7.19
7.05
5.61
<0.02
Dysidavarone A (1)
2
3
4
Taxol
a
7
86-O (Human kidney carcinoma cells).
b
PC-3 (Human prostate cancer cells).
Experimental Section
General Experimental Procedures. Optical rotation was measured with a Perkin-Elmer 341 MC
polarimeter. HR-EIMS spectra were obtained with a Q-TOF Micro LC-MS-MS spectrometer, and
ESI-MS spectra with an Agilent 1100 1946 DLC-MS spectrometer. NMR spectra were acquired on a
Varian INOVA 400 MHz and Bruker AM-400 spectrometer with TMS as the internal standard. Data are
reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet, dd = doublet of
doublet, b = broad, q = quartet, m = multiplet). Infrared spectra were measured using film KBr pellet
techniques and were acquired using a Shimadzu FTIR-8400S spectrometer. Column chromatography (CC)
separations were carried out using silica gel H60 (300-400 mesh, Qingdao Haiyang Chemical Group
Corp.). 786-O and PC-3 cells were obtained from Shanghai Institute of Material Medica of Chinese
Academy of Sciences and were grown in RPMI-1640 and DMEM/F12 medium containing 5% fetal
bovine serum.
9

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2
-methyl-2-(3-oxopentyl)cyclohexane-1, 3-dione (10): To a solution of 2-methyl-1, 3-cyclohexadione (9)
(
3.6 g, 28.7 mmol) in ethyl acetate (200 mL) were added triethylamine (5.2 mL, 37.3 mmol) and ethyl
vinyl ketone (3.1 mL, 31.2 mmol). The reaction mixture was heated at 70 °C for 10 hrs and then cooled to
5 °C. The solvent was removed under reduced pressure and the residue was purified by column
2
chromatography eluted with petroleum ether/ethyl acetate (1:2) to give triketone 10 (5.74 g, 94%) as a
1
pink oil. H NMR (400 MHz, CDCl
3
H
) δ : 2.76-2.68 (m, 2H), 2.65-2.57 (m, 2H), 2.40 (t, J=7.2 Hz, 1H),
2
3
.32-2.28 (t, J=7.2, 7.6 Hz, 2H), 2.08-1.99 (m, 3H), 1.94-1.84 (m, 1H), 1.22 (s, 3H), 1.02 (t, J=8.0 Hz,
1
3
3
H); C NMR (100 MHz, CDCl ) δc: 209.8, 209.6, 63.9, 37.3, 36.5, 35.5, 29.3, 19.3, 17.1, 7.2. IR (KBr)
-1
+
νmax: 2976, 2939, 1716, 1686, 1458, 1375, 1364, 1340, 1319, 1115, 1026 cm ; MS [M+H] m/z (%):
2
11.2 (80).
(S)-5, 8a-dimethyl-3, 4, 8, 8a-tetrahydronaphthalene-1, 6 (2H, 7H)-dione (11): A solution of the triketone
1
0 (2.9 g, 13.6 mmol), L-α-phenylalanine (2.26 g, 13.6 mmol) and D-camphorsulfonic acid (1.58 g, 6.8
mmol) in DMF (30 mL) was stirred at 25 °C under argon atmosphere overnight. The mixture was then
heated at 30 °C for 24 hrs, and the temperature was raised in 10 °C intervals every 24 hrs in 4 days. Then
the mixture was stirred at 70 °C for additional 24 hrs. The reactant was poured into cold 5% aqueous
solution of NaHCO (100 mL), extracted with ethyl ether (2 × 60 mL), then dried over anhydrous Na SO .
3
2
4
After removal solvent under reduced pressure, the residue was purified by column chromatography eluted
2
5
with petroleum ether/ethyl acetate (1:3) to give enone 11 (2.22 g, 85%) as a light yellow oil. [α]D +132 (c
1
0
2
1
.85, CHCl ); H NMR (400 MHz, CDCl ) δ : 2.88-2.82 (m, 1H), 2.67-2.63 (m, 1H), 2.53-2.39 (m, 4H),
3
3
H
13
.16-2.03 (m, 3H), 1.80 (s, 3H), 1.78-1.74 (m, 1H), 1.41 (s, 3H); C NMR (100 MHz, CDCl
3
) δc: 212.3,
97.9, 158.4, 130.9, 50.9, 37.6, 33.5, 29.8, 27.5, 23.6, 21.7, 11.5. IR (KBr) νmax: 2974, 2943, 1709, 1647,
1
0

ACCEPTED MANUSCRIPT
-1
+
1
635, 1448, 1420, 1375, 1362, 1317, 1167, 1026 cm ; MS [M+H] m/z (%): 193.2 (100).
(S)-5', 8a'-dimethyl-3', 4', 8', 8a'-tetrahydro-2'H-spiro{[1, 3]dioxolane-2, 1'-naphthalen}-6'(7'H)-one (8):
To a solution of compound 11 (1.75 g, 9.1 mmol) in DCM (17 mL), 2-ethyl-2-methyl-3-dioxolane (17
mL), ethylene glycol (60 mg, 0.9 mmol) and p-toluenesulfonic acid (180 mg, 0.9 mmol) were added. The
solution was stirred at 25 °C for 48 hrs, and then the mixture of triethylamine (1 mL) in DCM (60 mL)
were added. The organic phase was washed with saturated aqueous NaCl solution and dried over
2 4
anhydrous Na SO . The solvent was removed under reduced pressure and the residue was purified by
column chromatography eluted with petroleum ether/ethyl acetate (5:1) to give compound 8 (1.94 g, 90%)
2
5
1
as a light yellow oil. [α]D +115 (c 0.52, MeOH); H NMR (400 MHz, CDCl ) δ : 3.98-3.90 (m, 4H),
3
H
1
3
2
.76-2.63 (m, 1H), 2.53-2.37 (m, 2H), 2.24-2.10 (m, 2H), 1.93-1.57 (m, 8H), 1.33 (s, 3H); C NMR (100
MHz, CDCl ) δc: 198.9, 160.4, 130.4, 113.0, 65.6, 65.3, 45.5, 33.9, 29.9, 26.75, 26.71, 21.7, 21.1, 11.7;
3
-1
+
IR (KBr) νmax: 2941, 2856, 1707, 1686, 1458, 1175, 1262, 1032, 950 cm ; MS [M+H] m/z (%): 237.2
(100).
3
, 5-Diethoxytoluene (13): See compound 21 for similar procedure. Compound 13 was obtained as pale
1
yellow oil in 97% yield; H NMR (400 MHz, CDCl ) δ : 6.32 (d, J=1.6 Hz, 2H), 6.27 (s, 1H), 4.01 (q,
3
H
1
3
J=6.8 Hz, 4H), 2.28 (s, 3H), 1.39 (t, J=6.8 Hz, 6H); C NMR (100 MHz, CDCl ) δc: 160.2, 140.3, 107.8,
3
9
8
8.7, 63.5, 22.0, 15.1; IR (KBr) νmax: 2980, 2922, 1593, 1470, 1391, 1342, 1319, 1292, 1169, 1157, 1065,
-
1
+
18, 687 cm ; MS [M+H] m/z (%): 181.1 (100).
2
, 4-diethoxy-6-methylbenzaldehyde (14): A solution of phosphoryl chloride (12.1 mL, 130.6 mmol) in
dried DMF (24 mL) was added to a stirred solution of 3, 5-Diethoxytoluene (19.6 g, 108.8 mmol) in 34
11

ACCEPTED MANUSCRIPT
o
mL of dried DMF at 100 - 110 C over a period of 30 min under nitrogen atmosphere. Continue stirring at
o
1
00-110 C for 1 hr, the reaction mixture was poured into ice-water. The pH of the aqueous solution was
adjusted to pH 8 with saturated aqueous K CO solution. The precipitate formed was collected and dried
2
3
o
1
to afford 2, 4-diethoxy-6-methylbenzaldehycle (14) (20.6 g, 91%) as an off-white solid. Mp. 92-94 C; H
NMR (400 MHz, CDCl ) δ : 10.5 (s, 1H), 6.28 (s, 2H), 4.08 (q, J=7.2 Hz, 4H), 2.55 (s, 3H), 1.45 (t, J=6.8,
3
H
1
3
7
2
1
.2 Hz, 6H); C NMR (100 MHz, CDCl ) δc: 190.9, 164.9, 164.0, 144.7, 117.5, 109.4, 97.1, 64.5, 63.9,
3
2.5, 14.9, 14.8; IR (KBr) νmax: 2934, 2860, 2777, 1749, 1663, 1603, 1576, 1558, 1456, 1396, 1325, 1292,
-
1
+
163, 1115, 1057, 849, 837, 787, 700, 507 cm ; MS [M+H] m/z (%): 209.2 (100).
2
, 4-diethoxy-6-methylphenol (15): KHSO (2.53 g, 18.6 mmol) and 10% of H O (11.6 mL, 114.0 mmol)
4
2
2
o
were added to a solution of 14 (19.3 g, 92.7 mmol) in methanol (500 mL) sequentially at 4 C. The
mixture was stirred at 25 °C for 4 hrs, 5% aqueous solution of KHSO (15 mL) was added to quench the
3
reaction and the solvent was removed under reduced pressure. The residue was extracted with EtOAc (2 ×
3
50 mL), the extract was washed with water (2 × 150 mL) and dried over Na SO . The solvent was
2 4
o
1
removed under reduced pressure to give 15 (16.4g, 90%) as a light yellow solid. Mp. 116-118 C; H
NMR (400 MHz, CDCl ) δ : 6.34 (d, J=2.4 Hz, 1H), 6.27 (d, J=2.4 Hz, 1H), 5.32 (s, 1H), 4.08 (q, J=6.8
3
H
1
3
Hz, 2H), 3.98 (q, J=6.8 Hz, 2H), 2.23 (s, 3H), 1.44 (t, J=6.8, 7.2 Hz, 3H), 1.39 (t, J=6.8 Hz, 3H); C
NMR (100 MHz, CDCl ) δc: 151.4, 145.3, 137.5, 123.1, 106.9, 97.7, 64.0, 63.5, 15.3, 14.5, 14.4; IR (KBr)
3
-1
+
νmax: 3433, 2924, 2853, 2856, 2362, 1655, 1657, 1458, 1465, 1240, 669 cm ; MS [M+H] m/z (%): 197.3
(100).
1
, 2, 5-triethoxy-3-methylbenzene (16): See compound 21 for similar procedure. Compound 16 was
1
obtained as colorless oil in 96% yield; H NMR (400 MHz, CDCl
3
H
) δ : 6.33 (d, J=2.4 Hz, 1H), 6.27 (d,
1
2

ACCEPTED MANUSCRIPT
1
3
J=2.0 Hz, 1H), 4.03-3.92 (m, 6H), 2.24 (s, 3H), 1.44-1.33 (m, 9H); C NMR (100 MHz, CDCl
3
) δc:
1
2
55.1, 152.8, 140.9, 132.3, 106.9, 99.6, 68.5, 64.3, 63.8, 16.7, 15.9, 15.1; IR (KBr) νmax: 3433, 2930, 2361,
-1
+
330, 1707, 1466, 1331, 1117, 1072, 669 cm ; MS [M+H] m/z (%): 225.1 (20).
2
-bromo-3-(bromomethyl)-1, 4, 5-triethoxybenzene (7): To a solution of 16 (8.0 g, 35.7 mmol) in CCl4
(600 mL) was added AIBN (293 mg, 1.79 mmol) and NBS (20.4 g, 114.3 mmol). The mixture was
refluxed for 4 hrs in the presence of light. The precipitate was filtered off and the filtrate was concentrated
under reduce pressure to give the crude product. The residue was washed with 30 mL petroleum ether
(containing 10% of ethyl acetate) to give compound 7 (11.0 g, 81%) as a pale yellow solid. Mp. 121-125
o
1
C; H NMR (400 MHz, CDCl ) δ : 6.51 (s, 1H), 4.75 (s, 2H), 4.15 (q, J=6.8, 7.2 Hz, 2H), 4.06 (q, J=6.8
3
H
1
3
Hz, 4H), 1.45-1.40 (m, 9H); C NMR (100 MHz, CDCl ) δc: 151.6, 151.2, 141.4, 131.6, 104.9, 100.8,
3
6
1
8.9, 65.3, 64.2, 28.2, 15.2, 14.4; IR (KBr) νmax: 2976, 2934, 2889, 1558, 1657, 1458, 1419, 1387, 1339,
-1
+
244, 1215, 1115, 1034, 1003, 927, 881, 806 cm ; MS [M+H] m/z (%): 381.0 (65).
(4a'S, 5'S, 8a'S)-5', 8a'-dimethylhexahydro-2'H-spiro [[1, 3]dioxolane-2, 1'-naphthalen]-6'(7'H)-one (17):
A solution of compound 8 (200 mg, 0.85 mmol) and H O (15.3 µL, 0.85 mmol) in THF (2 mL) was added
2
drop wise to a solution of Li (24 mg, 3.4 mmol) in liquid ammonia (5 mL) at -78 °C in 30 min. The
reaction mixture was stirred at -35 °C for 1 hr. The reaction was quenched with ammonium chloride (500
mg). 10 mL H O was added into the mixture and then extracted with ethyl ether (2 × 10 mL). The
2
combined organic layer was dried over anhydrous Na SO and concentrated under reduced pressure. The
2
4
residue was purified by column chromatography eluted with petroleum ether/ethyl acetate (5:1) to give 17
2
D
5
1
(180 mg, 89%) as a colourless oil. [α]
3 3 H
−3.6 (c 0.96, CHCl ); H NMR (400 MHz, CDCl ) δ : 3.94-3.84
(m, 4H), 2.42-2.33 (m, 2H), 2.24-2.19 (m, 1H), 1.90-1.89 (m, 1H), 1.76-1.46 (m, 7H), 1.22 (s, 3H). 0.97(d,
1
3

ACCEPTED MANUSCRIPT
13
J=6.4 Hz, 3H); C NMR (100 MHz, CDCl
3
) δc: 212.8, 112.5, 65.1, 64.9, 48.1, 44.9, 42.4, 37.5, 30.7,
-1
2
9.9, 24.9, 22.7, 14.2, 11.7; IR (KBr) νmax: 2951, 2878, 1700, 1445, 1186, 1086, 1040, 916 cm ; MS
+
[
M+H] m/z (%): 239.2 (100).
(4a'S, 5'S, 8a'S)-5'-(2-bromo-3, 5, 6-triethoxybenzyl)-5', 8a'-dimethylhexahydro-2'H-spiro [[1, 3]
dioxolane-2, 1'-naphthalen]-6' (7'H)-one (6): See compound 23 for similar procedure. Compound 6 was
o
25
1
obtained as white solid in 8% yield; Mp. 147-152 C; [α]
CDCl ) δ : 6.50 (s, 1H), 4.08-3.91 (m, 9H), 3.83-3.81 (m, 1H), 3.33 (d, J=13.6 Hz, 1H), 3.07 (d, J=13.6
Hz, 1H), 2.97-2.92 (m, 1H), 2.97-2.92 (m, 1H), 2.34-2.28 (m, 3H), 1.70-1.39 (m, 16H), 1.34 (t, J=6.8, 7.2
D
+29 (c 0.07, EtOH); H NMR (400 MHz,
3
H
1
3
Hz, 3H), 1.02 (s, 3H), 1.01 (s, 3H); C NMR (100 MHz, CDCl ) δc: 215.4, 150.9, 150.6, 142.5, 132.1,
3
1
1
9
12.6, 107.6, 101.1, 67.8, 65.3, 64.9, 64.5, 64.1, 51.1, 47.3, 41.6, 40.1, 34.2, 29.3, 29.1, 22.6, 22.3, 17.8,
5.3, 14.5, 14.4; IR (KBr) νmax: 3369, 2928, 2864, 2361, 1709, 1578, 1383, 1339, 1232, 1184, 1117, 1074,
-1
+
51, 810 cm ; HRMS [M+Na] m/z 561.1796 (calc. 561.1822 for C H BrNaO ).
2
7
39
6
(4aS, 5S, 11S, 12aS)-7, 8, 10-triethoxy-5, 12a-dimethyl-3, 4, 4a, 5, 6, 11, 12, 12a-octahydro-2H-spiro [5,
1
1-ethanodibenzo [a, e] [8] annulene-1, 2'-[1, 3] dioxolan]-13-one (18): See compound 32 for similar
2
5
1
procedure. Compound 18 was obtained as pale yellow foam in 72% yield; [α]D +37 (c 0.075, EtOH); H
NMR (400 MHz, CDCl ) δ : 6.40 (s, 1H), 4.07-3.77 (m, 10H), 3.66 (d, J=8.8, 13.2 Hz, 1H), 1.62-1.31 (m,
3
H
1
3
1
1
1
9
5H), 1.17 (s, 3H), 0.99 (s, 3H); C NMR (100 MHz, CDCl ) δc: 220.7, 151.4, 149.9, 139.2, 128.2, 123.7,
3
11.8, 97.6, 67.7, 64.7, 63.9, 63.4, 46.3, 46.1, 43.3, 42.2, 41.4, 38.6, 29.1, 22.7, 21.9, 17.5, 17.4, 15.3,
4.6, 14.5; IR (KBr) νmax: 2978, 2935, 2880, 2359, 2332, 1718, 1597, 1383, 1331, 1229, 1184, 1072, 1053,
-
1
+
6
14, 802 cm ; HRMS [M+Na] m/z 481.2583 (calc. 481.2561 for C27H38NaO ).
1
4

ACCEPTED MANUSCRIPT
(4aR, 5S, 11S, 12aS)-7, 8, 10-triethoxy-5, 12a-dimethyl-2, 3, 4, 4a, 5, 6, 12, 12a-octahydro-5,
1
1-methanodibenzo [a, e] [8] annulene-1, 13 (11H)-dione (5): See compound 27 for similar procedure.
o
25
D
Compound 5 was obtained as light yellow solid in 88% yield; Mp. 167-170 C; [α] +12 (c 0.065, EtOH);
1
H NMR (400 MHz, CDCl ) δ : 6.39 (s, 1H), 4.07-3.84 (m, 7H), 3.75 (d, J=9.2 Hz, 1H), 3.39 (d, J=17.2
3
H
Hz, 1H), 2.63 (d, J=14.4 Hz, 1H), 2.55-2.49 (m, 3H), 2.22-2.02 (m, 4H), 1.84-1.78 (m, 3H), 1.46-1.25 (m,
1
3
1
6
2H), 1.09 (s, 3H); C NMR (100 MHz, CDCl ) δc: 219.0, 213.4, 151.5, 150.1, 138.9, 127.5, 123.0, 97.4,
3
7.8, 64.1, 63.3, 49.2, 46.9, 46.5, 43.0, 41.6, 39.9, 37.2, 24.9, 22.8, 19.4, 17.5, 15.2, 14.5, 14.4; IR (KBr)
-1
ν
max: 2976, 2938, 2872, 2361, 1718, 1701, 1597, 1470, 1387, 1331, 1232, 1128, 1072, 1036, 974, 800 cm ;
+
HRMS [M+Na] m/z 437.2318 (calc. 437.2298 for C25
H34NaO
5
).
3
, 5-Diethoxybenzyl alcohol (21): A mixture of 3, 5-dihydroxybenzyl alcohol (24 g, 171.3 mmol), diethyl
sulfate (55.9 mL, 428.1 mmol) and potassium carbonate anhydrous (71.0 g, 513.9 mmol) in acetone (500
mL) was refluxed under nitrogen for 18 hrs. After cooling, the solution was filtered, the cake was washed
with acetone (50 mL) and the filtrate was evaporated under reduced pressure. The residue was then
purified by column chromatography eluted with petroleum ether/ethyl acetate (5:1) to give
1
3
6
6
2
,5-Diethoxybenzyl alcohol (21) (32.7 g, 97.3%) as a colorless liquid. H NMR (400 MHz, CDCl
3
) δ
H
:
.51 (d, J=2.4 Hz, 2H), 6.39 (t, J=2.0, 2.4 Hz, 1H), 4.62 (s, 2H), 4.03 (q, J=6.8 Hz, 4H), 1.42 (t, J=6.8 Hz,
1
3
H); C NMR (100 MHz, CDCl ) δc: 159.8, 142.8, 104.6, 100.1, 64.9, 63.0, 14.3; IR (KBr) νmax: 3442,
3
-1
+
980, 2930, 1597, 1456, 1393, 1292, 1171, 1115, 1059, 1032, 972, 841, 708, 689 cm ; MS [M+H] m/z
%): 197.1 (100).
(
1
5
-(bromomethyl)-3, 5-diethoxybenzene (22): PBr
3
(15.8 mL) was added dropwise to a solution of 3,
-diethoxybenzyl alcohol (21) (32.7 g, 166.6 mmol) and pyridine (0.67 mL, 8.3 mmol) in DCM (500 mL)
1
5

ACCEPTED MANUSCRIPT
o
at 0 C. The mixture was stirred at room temperature for 4 hrs. Then the reaction was quenched with ice
water (600 mL), extracted with DCM (2 × 300 mL), washed with brine (2 × 200 mL), dried over
anhydrous Na SO , and concentrated to provide 1-(bromomethyl)-3, 5-diethoxybenzene (22) as a grey
2
4
solid. (42.3g, 98.4%) The crude product can be used for next step of reaction without further purification.
o
1
Mp. 53-56 C; H NMR (400 MHz, CDCl ) δ: 6.54 (d, J=2.4 Hz, 2H), 6.40 (t, J=2.0, 2.4 Hz, 1H), 4.43 (s,
3
1
3
2
1
1
H), 4.03 (q, J=6.8 Hz, 4H), 1.42 (t, J=6.8 Hz, 6H); C NMR (100 MHz, CDCl ) δc: 159.7, 139.1, 107.0,
3
01.0, 63.1, 33.3, 14.3; IR (KBr) νmax: 2972, 2930, 2883, 2862, 1684, 1597, 1558, 1456, 1394, 1317, 1169,
-1
+
113, 1057, 847, 822, 690, 550, 498 cm ; MS [M+H] m/z (%): 259.1 (80).
(4a'S, 5'S, 8a'S)-5'-(3, 5-diethoxybenzyl)-5', 8a'-dimethylhexahydro-2'H-spiro [[1, 3] dioxolane-2,
1
'-naphthalen]-6' (7'H)-one (23): Compound 8 (1.2 g, 5.1 mmol) in dried THF (30 mL) was added
dropwise to a stirred solution of lithium (321 mg, 45.9 mmol) in liquid ammonia (50 mL) at -78 °C under
argon. The resulting solution was refluxed for 1 hrs, and then a solution of 22 (9.16 g, 35.5 mmol) in dried
THF (15 mL) was added. The mixture was allowed to stand for 2 hrs at 25 °C until liquid ammonia be
evaporated. Then, the saturated aqueous ammonium chloride (20 mL) was added, and the mixture was
extracted with diethyl ether (3 × 30 mL). The combined organic layer was washed with brine, dried over
anhydrous Na SO . After removal the solvent under reduced pressure, the residue was purified by column
2
4
chromatography eluted with petroleum ether/ethyl acetate (10:1) to give 23 (1.74 g, 82%) as a white foam.
2
5
1
[
α]D +47 (c 0.03, MeOH); H NMR (400 MHz, CDCl ) δ : 6.31 (t, J=2.0, 2.4 Hz, 1H), 6.24 (d, J=2.0 Hz,
3 H
2
2
H), 4.00 (q, J=6.8 Hz, 4H), 3.91-3.80 (m, 4H), 3.10 (d, J=13.6 Hz, 1H), 2.49 (d, J=13.2 Hz, 1H),
.41-2.38 (m, 1H), 2.31-2.25 (m, 1H), 1.76-1.55 (m, 4H), 1.52-1.37 (m, 11H), 1.13 (s, 3H), 1.10 (s, 3H);
1
3
C NMR (100 MHz, CDCl
3
) δc: 216.3, 159.1, 139.9, 112.2, 108.6, 99.7, 64.6, 64.3, 62.9, 51.8, 44.5, 42.7,
4
1.7, 35.0, 29.7, 27.4, 22.2, 21.9, 21.8, 16.0, 14.4; IR (KBr) νmax: 2978, 2935, 2363, 1699, 1595, 1173,
1
6

ACCEPTED MANUSCRIPT
-
1
+
1
2
5
059, 949, 908, 866, 820, 719, 669 cm ; HRMS [M+Na] m/z 439.2459 (calc. 439.2455 for C25H36NaO ).
-bromo-1-(bromomethyl)-3, 5-diethoxybenzene (24): See compound 25 for similar procedure.
o
1
Compound 24 was obtained as a white solid in 91% yield; Mp. 107-110 C; H NMR (400 MHz, CDCl )
3
δH: 6.62 (d, J=2.8 Hz, 1H), 6.43 (d, J=2.4 Hz, 1H), 4.60 (s, 2H), 4.08 (m, 4H), 1.50 (t, J=6.8 Hz, 3H), 1.54
1
3
(
t, J=6.8, 7.2 Hz, 3H); C NMR (100 MHz, CDCl ) δc: 158.5, 156.0, 137.9, 107.2, 104.8, 100.8, 64.5,
3
6
1
3.4, 33.7, 14.3, 14.2; IR (KBr) νmax: 2982, 2934, 2885, 1603, 1582, 1456, 1391, 1331, 1184, 1117, 1074,
-
1
+
026, 889, 851, 806, 717, 660, 627 cm ; MS [M+H] m/z (%) 337.0 (15).
(4a'S, 5'S, 8a'S)-5'-(2-bromo-3, 5-diethoxybenzyl)-5', 8a'-dimethylhexahydro-2'H-spiro [[1, 3] dioxolane-2,
1
4
'-naphthalen]-6'(7'H)-one (25): To a solution of 23 (1.60 g, 3.84 mmol) in DCM (75 mL), NBS (0.72 g,
o
.03 mmol) was added at 0 °C and the reaction was stirred at 0 C for 1 hrs. The reaction mixture was
quenched with saturated aqueous NaHCO (15 mL). Then the mixture was diluted with H O (30 mL),
3
2
extracted with EtOAc (3 × 60 mL). The combined organic layer was then washed with brine (20 mL),
dried over anhydrous MgSO , and then concentrated under reduced pressure. The residue was purified by
column chromatography eluted with petroleum ether/ethyl acetate (10:1) to give compound 25 (1.83 g,
4
2
5
1
9
6
2
2%) as a white foam. [α]D +10 (c 0.06, MeOH); H NMR (400 MHz, CDCl ) δ : 6.31 (d, J=2.8 Hz, 1H),
3 H
.21 (d, J=2.4 Hz, 1H), 4.03-3.79 (m, 8H), 3.15 (d, J=14.4 Hz, 1H), 3.00 (d, J=14.0 Hz, 1H), 2.47-2.43 (m,
1
3
H), 2.22-2.19 (m, 1H), 1.84-1.81 (m, 1H), 1.65-1.33 (m, 13H), 1.06 (s, 6H); C NMR (100 MHz, CDCl )
3
δc: 216.9, 157.6, 155.3, 138.9, 112.1, 107.7, 107.1, 99.6, 64.5, 64.4, 64.2, 63.0, 51.9, 44.3, 43.4, 41.7,
3
1
5.0, 29.4, 27.8, 22.4, 22.1, 20.6, 16.3, 14.2, 14.1; IR (KBr) νmax: 2982, 2937, 2883, 1697, 1657, 1589,
-
1
+
340, 1178, 1138, 1045, 1020, 951, 806 cm ; HRMS [M+Na] m/z 517.1556 (calc. 517.1560 for
25 5
C H35BrNaO
).
1
7

ACCEPTED MANUSCRIPT
(4aS, 5S, 11S, 12aS)-8,10-diethoxy-5, 12a-dimethyl-3, 4, 4a, 5, 6, 11, 12, 12a-octahydro-2H-spiro [5,
1
1-methanodibenzo [a, e] [8] annulene-1, 2'-[1, 3] dioxolan]-13-one (26): An oven-dried 100 mL
round-bottomed flask was charged with Pd (dba) (439 mg, 0.49 mmol), xant-Phos (232 mg, 0.49 mmol)
2
3
and anhydrous t-BuONa (701 mg, 7.29 mmol). A solution of 25 (1200 mg, 2.43 mmol) in anhydrous
dioxane (30 mL) was added under Ar, and the suspension was heated to reflux for 4 hrs. After cooling to
2
5 °C, the reaction mixture was diluted with EtOAc (30 mL), filtered over celite, and concentrated under
reduced pressure. The residue was purified by column chromatography eluted with petroleum ether/ethyl
1
acetate (12:1) gave 26 (886 mg, 88%) as a pale yellow foam. H NMR (400 MHz, CDCl
3
) δ
H
: 6.32 (s, 1H),
6
.13 (s, 1H), 4.04-3.96 (m, 4H), 3.88-3.77 (m, 4H), 3.66 (d, J=9.2 Hz, 1H), 3.03 (d, J=16.4 Hz, 1H), 2.75
(d, J=16.4 Hz, 1H), 2.64-2.60 (m, 1H), 2.45 (d, J=13.6 Hz, 1H), 1.95 (t, J=9.2, 4.0 Hz, 1H), 1.14 (s, 3H),
1
3
1
6
3
.00 (s, 3H); C NMR (100 MHz, CDCl ) δc: 220.21, 158.1, 156.5, 134.5, 123.3, 111.9, 103.9, 97.5, 64.7,
3
3.9, 62.9, 62.8, 48.5, 46.7, 46.2, 42.0, 41.3, 38.3, 29.1, 22.8, 22.0, 17.3, 14.42, 14.36; IR (KBr) νmax
:
-1
25
D
367, 3337, 2980, 2934, 2883, 1717, 1178, 1134, 1072, 1022 cm ; [α] +43 (c 0.075, MeOH); HRMS
+
+
(
5
ESI ): [M+Na] m/z 437.2303 (calc. 437.2298 for C25H34NaO ).
(
4aR, 5S, 11S, 12aS)-8, 10-diethoxy-5, 12a-dimethyl-2, 3, 4, 4a, 5, 6, 12, 12a-octahydro-5,
1-ethanodibenzo [a, e] [8] annulene-1, 13(11H)-dione (27): 3.0 M hydrochloric acid (9.7 mL, 39.8 mmol)
1
was added to a stirred solution of 26 (1.10 g, 2.66 mmol) in THF (20 mL) at 25 °C. After 2 h stirring, the
reaction was quenched with saturated aqueous sodium hydrogen carbonate (6 mL), and the mixture was
extracted with ethyl acetate (3 × 30 mL). The combined extracts were washed with brine (30 mL), dried
over anhydrous Na
2 4
SO , concentrated under reduced pressure afforded an oily residue, which was purified
by column chromatography using petroleum ether/ethyl acetate (12:1) as elute gave 27 (905 mg, 92%) as
1
8

ACCEPTED MANUSCRIPT
o
25
1
a pale yellow solid. Mp. 147-151 C; [α]
D
+28 (c 0.05, MeOH); H NMR (400 MHz, CDCl
H), 6.09 (s, 1H), 4.03-3.93 (m, 4H), 3.73 (d, J=9.6 Hz, 1H), 3.03 (d, J=16.8 Hz, 1H), 2.76 (d, J=16.4 Hz,
H), 2.57-2.44 (m, 3H), 2.19-2.00 (m, 1H), 1.81-1.73 (m, 2H), 1.47-1.39 (m, 7H), 1.22 (s, 3H), 1.06 (s,
3 H
) δ : 6.29 (s,
1
1
3
4
2
1
3
H); C NMR (100 MHz, CDCl ) δc: 218.5, 213.2, 158.4, 156.6, 133.8, 122.9, 103.8, 97.4, 62.97, 62.92,
3
8.9, 48.1, 46.9, 46.8, 41.4, 39.8, 37.1, 24.9, 22.8, 19.3, 17.4, 14.4, 14.3; IR (KBr) νmax: 2934, 2378, 2303,
-1
+
181, 1705, 1508, 1178, 1121, 1070, 839 cm ; HRMS [M+Na] m/z 393.2039 (calc. 393.2036 for
23 4
C H30NaO
).
(4aR, 5S, 11R, 12aS)-8, 10-diethoxy-5, 12a-dimethyl-1, 13-dimethylene-1, 2, 3, 4, 4a, 5, 6, 11, 12,
1
2a-decahydro-5, 11-methanodibenzo [a, e] [8] annulene (28): A mixture of t-BuOK (3.75g, 33.4 mmol)
and methyltriphenylphosphonium bromide (12.54g, 35.1 mmol) in dry toluene (80 mL) was refluxed at 90
o
C for 1 hr under argon. The resulted solution was cooled to 25 °C. A solution of 27 (650 mg, 1.76 mmol)
o
in toluene (50 mL) was added to above prepared mixture. The reactant was stirred at 90 C for 40 hrs
under argon and quenched with water (60 mL). After extracted with EtOAc (2 × 50 mL), the combined
2 4
organic layer was washed with brine (30 mL), dried over anhydrous Na SO . After concentered under
reduced pressure, the residue was purified by column chromatography eluted with petroleum ether/ethyl
o
25
D
acetate (100:1) gave 27 (580 mg, 90%) as a pale yellow solid. Mp. 85-89 C; [α] +46 (c 0.07, MeOH);
1
H NMR (400 MHz, CDCl ) δ : 6.31 (d, J=2.0 Hz, 1 H), 6.11 (d, J=2.0 Hz, 1H), 4.93 (d, J=0.8 Hz, 1H),
3
H
4
.82 (d, J=1.2 Hz, 1H), 4.51 (d, J=1.2 Hz, 1H); 4.08-3.91 (m, 5H), 2.81 (d, J=16.0 Hz, 1H), 2.46 (d,
1
3
J=15.6 Hz, 1H), 1.81-1.73 (m, 2H), 1.47-1.39 (m, 7H), 1.22 (s, 3H), 1.06 (s, 3H); C NMR (100 MHz,
CDCl ) δc: 158.6, 157.4, 155.9, 155.3, 136.4, 126.3, 104.9, 104.5, 102.9, 97.0, 62.8, 48.7, 46.6, 43.5, 39.3,
3
3
1
8.4, 37.4, 32.7, 26.9, 24.5, 21.9, 20.5, 14.53, 14.48; IR (KBr) νmax: 2972, 2926, 2907, 2868, 1603, 1587,
-1
+
437, 1340, 1285, 1180, 1146, 1122, 1092, 1068, 885, 839 cm ; HRMS [M+Na] m/z 389.2455 (calc.
1
9

ACCEPTED MANUSCRIPT
3
2
89.2451 for C25H34NaO ).
(5R, 6aS, 10aR, 11S)-2-ethoxy-6a, 11-dimethyl-7, 13-dimethylene-5, 6, 6a, 7, 8, 9, 10, 10a, 11,
1
2-decahydro-5, 11-methanodibenzo [a, e] [8] annulene-1, 4-dione (2): A solution of CrO (467 mg, 4.67
3
mmol) in H O (2 mL) and AcOH (8 mL) was added drop wisely to the solution of compound 27 (450 mg,
2
1
.23 mmol) in AcOH (12 mL) at 0 °C. The reaction mixture was stirred at room temperature and
monitored by TLC (petroleum ether/EtOAc=10:1). After 30 min, ice water (20 mL) was added, and the
aqueous layer was extracted with EtOAc (2 × 30 mL). The combined organic layers were washed with
4 2 4
saturated NH Cl solution (30 mL), dried over anhydrous Na SO . After filtration, the solution was
concentration under reduced pressure. The residue was purified by column chromatography using
o
petroleum ether/ethyl acetate (10:1) as elute to give 2 (295 mg, 68%) as a pale yellow solid. Mp. 88-93 C;
2
5
1
[
(
(
(
α]D +17 (c 0.06, MeOH); H NMR (400 MHz, CDCl ) δ : 5.86 (s, 1H), 4.93 (s, 1H), 4.86 (s, 1H), 4.54
3 H
s, 1H), 4.50 (s, 1H), 4.00 (q, J=6.8 Hz, 2H), 3.77 (d, J=10.8 Hz, 1H), 2.75 (d, J=18.4 Hz, 1H), 2.22-1.95
1
3
m, 6H), 1.83-1.79 (m, 1H), 1.70-1.67 (m, 2H), 1.56-1.43 (m, 5H), 1.24 (s, 3H), 1.09 (s, 3H); C NMR
100 MHz, CDCl ) δc: 186.2, 182.3, 157.6, 157.3, 151.5, 148.5, 138.1, 107.1, 105.6, 105.2, 64.6, 48.7,
2.4, 41.6, 38.8, 37.8, 36.7, 32.6, 26.9, 24.3, 21.3, 20.2, 13.4; IR (KBr) νmax: 2930, 2860, 1717, 1647,
3
4
1
-1
+
219, 1111, 1034, 980, 891 cm ; HRMS [M+Na] m/z 375.1937 (calc. 375.1931 for C H NaO ).
2
3
28
3
(5R, 6aS, 10aR, 11S)-2-ethoxy-6a, 7, 11-trimethyl-13-methylene-6, 6a, 10, 10a, 11, 12-hexahydro-5,
1
1-methanodibenzo [a, e] [8] annulene-1, 4(5H, 9H)-dione (1): To a solution of 2 (100 mg, 0.28 mmol) in
o
AcOH (20 mL) was added PTSA (10 mg, 0.06 mmol), the mixture was stirred at 25 C for 12 hrs. Then
the solution was diluted with ice water (50 mL) and extracted into tert-Butyl methyl ether (3 × 20 mL).
2 4
The combined extract was washed with brine (2 × 20 mL), dried over anhydrous Na SO and concentrated
2
0

ACCEPTED MANUSCRIPT
under reduced pressure. The residue was purified by column chromatography eluted with petroleum
o
25
D
ether/ethyl acetate (10:1) to give compound 1 (92 mg, 92%) as a pale solid. Mp = 99-102 C; [α] +119
1
(
c 0.13, MeOH); H NMR (400 MHz, CDCl ) δ : 5.85 (s, 1H), 5.09 (s, 1H), 4.91 (s, 1H), 4.85 (s, 1H),
3
H
4
.00 (q, J=6.8, 7.2 Hz, 2H), 3.72 (d, J=10.4 Hz, 1H), 2.79 (d, J=18.4 Hz, 1H), 2.19-2.22 (dd, J=10.4, 14.0
Hz, 1H), 2.02-1.98 (m, 1H); 1.90-1.85 (m, 1H), 1.69-1.63 (m, 2H), 1.54-1.45 (m, 8H), 1.25 (s, 3H), 1.05
1
3
(
s, 3H); C NMR (100 MHz, CDCl ) δc: 186.2, 182.3, 157.3, 152.0, 148.6, 142.1, 138.8, 118.9, 107.1,
3
1
2
05.1, 64.6, 46.8, 42.4, 41.4, 37.4, 37.2, 36.6, 25.9, 19.96, 19.88, 19.3, 17.5, 13.4; IR (KBr) νmax: 2964,
-1
937, 1697, 1670, 1677, 1630, 1601, 1339, 1279, 1225, 1209, 1161, 1101, 1034, 889, 850 cm ; HRMS
+
[
M+Na] m/z 375.1936 (calc. 375.1931 for C23
H28NaO
3
).
(
4a'S, 5'S, 8a'S)-5'-(3, 5-dimethoxybenzyl)-5', 8a'-dimethylhexahydro-2'H-spiro [[1, 3] dioxolane-2,
'-naphthalen]-6'(7'H)-one (30): See compound 23 for similar procedure. Compound 30 was obtained as
1
2
5
1
white foam in 83% yield; [α]D +27 (c 0.13, MeOH); H NMR (400 MHz, CDCl ) δ : 6.32 (t, J=2.0, 2.4
3
H
Hz, 1H), 6.26 (d, J=2.4 Hz, 1H), 3.91-3.80 (m, 4H), 3.71 (s, 6H), 3.13 (d, J=13.6 Hz, 1H); 3.72 (d, J=13.6
Hz, 1H), 2.48-2.37 (m, 1H), 2.31-2.25 (m, 2H), 1.75-1.65 (m, 3H), 1.54-1.43 (m, 5H), 1.14 (s, 3H), 1.11
1
3
(
s, 3H); C NMR (100 MHz, CDCl
3
) δc: 216.2, 159.8, 140.2, 112.1, 107.9, 98.5, 64.6, 64.3, 54.8, 51.8,
4
1
4
4.4, 42.6, 41.7, 35.0, 29.7, 27.3, 22.2, 21.9, 21.8, 15.9; IR (KBr) νmax: 2943, 2883, 2837, 1701, 1595,
-1
+
460, 1429, 1344, 1294, 1205, 1184, 1151, 1099, 1059, 1045, 910, 829, 708 cm ; HRMS [M+Na] m/z
11.2161 (calc. 411.2142 for C H NaO ).
2
3
32
5
(4a'S, 5'S, 8a'S)-5'-(2-bromo-3, 5-dimethoxybenzyl)-5', 8a'-dimethyl-hexahydro-2'H-spiro [(1, 3)
-dioxolane-2, 1'-naphthalen]-6'(7'H)-one (31): See compound 25 for similar procedure. Compound 31 was
2
5
1
obtained as white foam in 91% yield; [α]
D 3 H
+25 (c 0.08, MeOH); H NMR (400 MHz, CDCl ) δ : 6.34 (d,
2
1

ACCEPTED MANUSCRIPT
J=2.8 Hz, 1H), 6.25 (d, J=2.8 Hz, 1H), 3.89-3.79 (m, 7H), 3.73 (s, 3H), 3.18 (d, J=13.2 Hz, 1H), 3.03 (d,
J=14.0 Hz, 1H), 2.49-2.43 (m, 2H), 2.23-2.19 (m, 1H), 1.84-1.82 (m, 1H), 1.77-1.41 (m, 7H), 1.09 (s, 3H),
1
3
1
6
2
.08 (s, 3H); C NMR (100 MHz, CDCl ) δc: 217.2, 158.4, 155.9, 139.2, 112.2, 107.0, 103.7, 97.9, 64.6,
3
4.3, 55.8, 54.9, 52.1, 44.3, 43.4, 41.8, 35.1, 29.5, 27.8, 22.4, 22.2, 20.8, 16.3; IR (KBr) νmax: 2937, 2881,
-1
856, 1701, 1591, 1458, 1437, 1381, 1340, 1288, 1202, 1163, 1082, 1022, 949, 910 cm ; HRMS
+
[
M+Na] m/z 489.1259 (calc. 489.1247 for C H BrNaO ).
2
3
31
5
(
4aS, 5S, 11S, 12aS)-8, 10-dimethoxy-5, 12a-dimethyl-3, 4, 4a, 5, 6, 11, 12, 12a-octahydro-2H-spiro [5,
1-methanodibenzo [a, e] [8] annulene-1, 2'-[1, 3] dioxolan]-13-one (32): In a sealed tube was charged
with Pd(OAc) (225 mg, 1.0 mmol), PPh (262 mg, 1.0 mmol) and Cs CO (3257 mg, 9.99 mmol), a
1
2
3
2
3
solution of 31 (1550 mg, 3.33 mmol) in anhydrous THF (60 mL) was added, the resulting suspension was
o
heated to 100 C for 24 hrs. After cooling to 25 °C, the reaction mixture was diluted with EtOAc (30 mL),
filtered through celite and then concentrated under vacuum. The residue was purified by column
chromatography eluted with petroleum ether/ethyl acetate (10:1) gave 32 (1093 mg, 85%) as a white foam.
2
D
5
1
[α]
+84 (c 0.05, MeOH); H NMR (400 MHz, CDCl
3 H
) δ : 6.34 (d, J=2.0 Hz, 1H), 6.15 (d, J=2.0 Hz,
1
H), 3.89-3.87 (m, 3H), 3.80-3.78 (m, 7H), 3.65 (d, J=9.2 Hz, 1H), 3.05 (d, J=16.4 Hz, 1H), 2.71 (d,
J=16.4 Hz, 1H), 2.63 (dd, J=4.8, 12.0 Hz, 1H), 2.42 (d, J=13.6 Hz, 1H), 1.95 (dd, J=9.2, 13.6 Hz, 1H),
1
3
1
1
.67-1.33 (m, 7H), 1.15 (s, 3H), 1.00 (s, 3H); C NMR (100 MHz, CDCl ) δc: 219.9, 158.8, 157.4, 134.6,
3
23.4, 111.8, 103.4, 96.5, 64.7, 63.9, 54.9, 54.7, 48.5, 46.7, 46.2, 41.9, 41.3, 38.4, 29.0, 22.8, 21.9, 17.3;
IR (KBr) νmax: 3431, 2976, 2937, 1717, 1609, 1589, 1458, 1339, 1209, 1132, 1074, 1053, 1018, 939, 825
-1
+
cm ; HRMS [M+Na] m/z 409.1994 (calc. 409.1985 for C H NaO ).
2
3
30
5
(4aR, 5S, 11S, 12aS)-8, 10-dimethoxy-5, 12a-dimethyl-2, 3, 4, 4a, 5, 6, 12, 12a-octahydro-5,
2
2

ACCEPTED MANUSCRIPT
1
1-methanodibenzo [a, e] [8] annulene-1, 13(11H)-dione (33): See compound 27 for similar procedure.
o
25
D
1
Compound 33 was obtained as white solid in 93% yield; Mp. 138−143 C; [α] +37 (c 0.07, MeOH); H
NMR (400 MHz, CDCl ) δ : 6.33 (d, J=2.0 Hz, 1H), 6.13 (d, J=1.6 Hz, 1H), 3.81(s, 3H), 3.77 (s, 3H),
3
H
3
3
2
2
1
.72 (d, J=9.6 Hz, 1H), 3.06 (d, J=16.4 Hz, 1H), 2.81 (d, J=16.4 Hz, 1H), 2.59-2.47 (m, 3H), 2.22-2.02 (m,
1
3
H), 1.85-1.76 (m, 2H), 1.53-1.43 (m, 1H), 1.25 (s, 3H), 1.09 (s, 3H); C NMR (100 MHz, CDCl ) δc:
3
18.2, 213.3, 159.1, 157.3, 133.9, 123.0, 103.3, 96.3, 54.9, 54.8, 48.9, 48.1, 46.98, 46.88, 41.3, 39.8, 37.1,
4.9, 22.8, 19.4, 17.4; IR (KBr) νmax: 3475, 2939, 2899, 1705, 1605, 1593, 1489, 1458, 1356, 1207, 1145,
-1
+
4
120, 1053, 976 928, 831 cm ; HRMS [M+Na] m/z 365.1732 (calc. 365.1723 for C21H26NaO ).
(4aR, 5S, 11R, 12aS)-8, 10-dimethoxy-5, 12a-dimethyl-1, 13-dimethylene-1, 2, 3, 4, 4a, 5, 6, 11, 12,
1
2a-decahydro-5, 11-ethanodibenzo [a, e] [8] annulene (34): See compound 28 for similar procedure.
o
25
D
1
Compound 34 was obtained as white solid in 92% yield; Mp. 81−86 C; [α] +66 (c 0.085, MeOH); H
NMR (400 MHz, CDCl ) δ : 6.32 (d, J=2.0 Hz, 1H), 6.13 (d, J=2.0 Hz, 1H), 4.92 (d, J=0.8 Hz, 1H), 4.81
3
H
(d, J=1.2 Hz, 1H), 4.51 (d, J=1.6 Hz, 1H), 3.90 (dd, J=5.2, 5.6 Hz, 1H), 3.84 (s, 3H), 3.77 (s, 3H), 2.82 (d,
J=16.0 Hz, 1H), 2.46 (d, J=16.0 Hz, 1H), 2.27-2.20 (m, 1H), 2.11-2.05 (m, 3H), 1.80-1.54 (m, 3H), 1.23
13
(
s, 3H), 1.13 (s, 3H); C NMR (100 MHz, CDCl
3
) δc: 158.5, 158.1, 156.6, 155.1, 136.5, 126.1, 105.1,
1
2
03.9, 102.9, 95.9, 54.9, 54.8, 48.7, 46.7, 43.5, 39.3, 38.4, 37.3, 32.7, 26.9, 24.5, 21.9, 20.5; IR (KBr) νmax
:
-1
989, 2930, 2854, 1630, 1605, 1593, 1487, 1458, 1354, 1213, 1196, 1088, 1122, 879, 827, 770, 629 cm ;
+
HRMS [M+Na] m/z 361.2143 (calc. 361.2138 for C H NaO ).
2
3
30
2
(5R, 6aS, 10aR, 11S)-2-methoxy-6a, 11-dimethyl-7, 13-dimethylene-5, 6, 6a, 7, 8, 9, 10, 10a, 11,
1
2-decahydro-5, 11-methanodibenzo [a, e] [8] annulene-1, 4-dione (3): See compound 2 for similar
o
25
procedure. Compound 3 was obtained as light yellow solid in 67% yield; Mp. 86-91 C; [α]
D
+19 (c
2
3

ACCEPTED MANUSCRIPT
1
0
.075, MeOH); H NMR (400 MHz, CDCl
3 H
) δ : 5.89 (s, 1H), 4.94 (s, 1H), 4.87 (s, 1H), 4.56 (s, 1H), 4.51
(s, 1H), 3.81 (s, 3H), 3.77 (s, 3H), 2.82 (d, J=16.0 Hz, 1H), 2.46 (d, J=16.0 Hz, 1H), 2.27-2.20 (m, 1H),
1
3
2
1
2
1
.11-2.05 (m, 3H), 1.80-1.54 (m, 3H), 1.23 (s, 3H), 1.13 (s, 3H); C NMR (100 MHz, CDCl ) δc: 185.9,
3
82.2, 158.1, 157.6, 151.4, 148.7, 138.2, 106.9, 105.6, 105.3, 55.7, 48.8, 42.4, 41.6, 38.8, 37.8, 36.8, 32.6,
6.9, 24.4, 21.3, 20.2; IR (KBr) νmax: 2964, 2926, 2877, 1697, 1670, 1647, 1602, 1558, 1458, 1231, 1221,
-
1
+
030, 885, 851, 775 cm ; HRMS [M+Na] m/z 361.1781 (calc. 361.1774 for C H NaO ).
2
2
26
3
(5R, 6aS, 10aR, 11S)-2-methoxy-6a, 7, 11-trimethyl-13-methylene-6, 6a, 10, 10a, 11, 12-hexahydro-5,
1
1-methanodibenzo [a, e] [8] annulene-1, 4(5H, 9H)-dione (4): See compound 1 for similar procedure.
o
25
D
Compound 4 was obtained as light yellow solid in 90% yield; Mp. 95−98 C; [α] +129 (c 0.085, MeOH);
1
H NMR (400 MHz, CDCl ) δ : 5.88 (s, 1H), 5.09 (d, J=3.2 Hz, 1H), 4.92 (s, 1H), 4.86 (s, 1H), 3.81 (s,
3
H
3
2
H), 3.73 (d, J=10.4 Hz, 1H), 2.80 (d, J=18.8 Hz, 1H), 2.20 (dd, J=10.4, 13.6 Hz, 1H), 2.04 (d, J=18.4 Hz,
13
H), 1.90-1.86 (m, 1H), 1.70-1.66 (m, 2H), 1.55-1.49 (m, 5H), 1.26 (s, 3H), 1.06 (s, 3H); C NMR (100
MHz, CDCl ) δ : 185.9, 182.2, 158.1, 157.6, 151.4, 148.7, 138.2, 106.9, 105.6, 105.3, 55.7, 48.8, 42.4,
3
C
4
1
3
1.6, 38.8, 37.8, 36.8, 32.6, 26.9, 24.4, 21.3, 20.2; IR(KBr) νmax: 2959, 2935, 1697, 1670, 1647, 1602,
-1
+
558, 1375, 1340, 1229, 1211, 1099, 1026, 1005, 887, 845 cm ; HRMS [M+Na] m/z 361.1786 (calc.
61.1774 for C H NaO ).
2
2
26
3
IC50 Value Determination for Human Kidney Carcinoma Cell lines 786-O and Human Prostate
Cancer Cell lines PC-3. Human kidney carcinoma cells 786-O and human prostate cancer cells PC-3 were
inoculated into 96 well microtiter plates at 10,000 and 7,500 cells/well in RPMI-1640 and DMEM/F12
medium containing 5% fetal bovine serum. After cell inoculation, the microtiter plates are incubated at
3
2
7° C, 5% CO , 95% air and 100% relative humidity for 24 hrs prior to addition of experimental drugs.
2
4

ACCEPTED MANUSCRIPT
After 24 hrs, two plates of each cell line are fixed in situ with TCA, to represent a measurement of the cell
population for each cell line at the time of compounds addition. At the time of compounds addition,
different compounds dilutions are added to the appropriate microtiter wells already resulting in the
required final drug concentrations. Following compounds addition, the plates are incubated for an
additional 48 hrs at 37 °C, 5% CO , 95% air, and 100% relative humidity. Cells are fixed in situ by cold
2
5
0% (w/v) TCA and incubated for 1 hr at 4 °C. The plates are washed five times with water and air dried.
Sulforhodamine B (SRB) solution (100 µL) at 0.4% (w/v) in 1% acetic acid is added to each well, and
plates are incubated for 10 minutes at room temperature. After staining, unbound dye is removed by
washing five times with 1% acetic acid and the plates are air dried. Bound stain is subsequently
solubilized with 10 mM trizma base, and the absorbance is read on an automated plate reader at a
wavelength of 515 nm.
Acknowledgment
This research was supported by Science & Technology Commission of Shanghai municipality (grant
number: 14401900600) and Jiangsu municipal government (333 high level talent funding project, grant
number: BRA2013081). The authors would like to thank Miss. Runzhong Fu from University of South
California, U.S.A for a very helpful linguistic modification. The authors also appreciate the help provided
by Prof. Peilan He from Shanghai Institute of Material Medica, Chinese Academy of Sciences and Dr.
Yibo Wang from Basilea Pharmaceutica China Ltd.
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2
5

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(
(
(
3) Ciavatta, M. L.; Lopez Gresa, M. P.; Gavagnin, M.; Romero, V.; Melck, D.; Manzo, E.; Guo, Y. W.;
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46-350.
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935-3938. (d) Ling, T.; Rivas, F.; Theodorakis, E. A. Tetrahedron Lett. 2002, 43, 9019-9022. (e)
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(
4
792-4802.
2
6

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2
7

ACCEPTED MANUSCRIPT
Total Synthesis of Dysidavarone A
Chunhui Yu, Xiaoguang Zhang, Jinghua Zhang and Zhengwu Shen*
O
Br
H
7
Steps,
OEt
O
3
4% overall yield
+
O
O
EtO
OEt
O
Dysidavarone A