Synthesis of the phenanthrene and cyclohepta[ a ]naphthalene skeletons via gold(I)-catalyzed intramolecular cyclization of unactivated cyclic 5-(2-arylethyl)-1,3-dienes

Article abstract of DOI:10.1021/jo200445p

The gold(I)-catalyzed hydroarylation of cyclohexa-1,3-dienes bearing an aryl group and a gem-diester in the tether proceeds in a 1,4-addition manner and in a diastereoselective fashion to afford perhydrophenanthrene rings. The reaction proceeded via attack of the aryl group onto the gold-activated cyclic dienes followed by rearomatization and protodeauration to generate perhydrophenanthrenes in good yields. This hydroarylation can be applied to the synthesis of perhydrocyclohepta[a]naphthalenes from aryl-tethered cycloheptadienes and the gold(I) catalyst.

Full text of DOI:10.1021/jo200445p

ARTICLE
pubs.acs.org/joc
Synthesis of the Phenanthrene and Cyclohepta[a]naphthalene
Skeletons via Gold(I)-Catalyzed Intramolecular Cyclization of
Unactivated Cyclic 5-(2-Arylethyl)-1,3-dienes
Ming-Chang P. Yeh,* Ming-Nan Lin, Yi-Shiang Chou, Tern-Chi Lin, and Li-Yu Tseng
Department of Chemistry, National Taiwan Normal University, 88 Ding-Jou Road, Section 4, Taipei 11677, Taiwan, Republic of China
S Supporting Information
b
ABSTRACT: The gold(I)-catalyzed hydroarylation of cyclo-
hexa-1,3-dienes bearing an aryl group and a gem-diester in the
tether proceeds in a 1,4-addition manner and in a diastereose-
lective fashion to afford perhydrophenanthrene rings. The
reaction proceeded via attack of the aryl group onto the gold-
activated cyclic dienes followed by rearomatization and proto-
deauration to generate perhydrophenanthrenes in good yields.
This hydroarylation can be applied to the synthesis of
perhydrocyclohepta[a]naphthalenes from aryl-tethered cycloheptadienes and the gold(I) catalyst.
’ INTRODUCTION
gold(I)-catalyzed hydroarylation of 5-(2-arylethyl)cyclohepta-1,
3-dienes afforded perhydrocyclohepta[a]naphthalene under the
same reaction conditions.
The construction of perhydrophenanthrene building blocks is
an important synthetic goal because such ring skeletons are
present in numerous natural products of biological interest.1
Because the availability of functionalized perhydrophenanthrene
building blocks could greatly facilitate the elaboration of more
complex target molecules, the design of expedient and efficient
synthetic routes to such intermediates has been actively
pursued.2 Many synthetic methods, as the key step, have been
developed in pursuit of perhydrophenanthrenes, including the
Robinson annulation of perhydronaphthalenone derivatives
bearing a tethered methyl ketone3 and the DielsꢀAlder reaction
of perhydronaphthalene derivatives with dienes.4 Among them,
the DielsꢀAlder cycloaddition is generally regarded as a high-
performance method for construction of phenanthrene skele-
tons. Recently, cationic phosphine gold(I) complexes have
emerged as versatile catalysts for electronic activation of unsatu-
rated carbonꢀcarbon bonds toward a variety of nucleophiles
under mild reaction conditions, allowing numerous synthetic
formations of unsaturated systems into useful structural motifs.5
Although gold(III)- and Ag(I)-catalyzed intermolecular Friedelꢀ
Crafts-type reaction of electron-rich phenols with cyclohexa-1,
3-diene followed by intramolecular hydroalkoxylation have been
reported to give benzofurans,6 the cationic gold(I) triphenylpho-
sphine complex (5 mol % of AuPPh3Cl/AgOTf) failed to
catalyze the annulation of phenols with dienes.6a We have now
demonstrated that the phosphine gold(I) can be applied toward
the synthesis of perhydrophenanthrenes by treatment of 5-(2-
arylethyl)cyclohexa-1,3-dienes with a catalytic amount of AuPPh3Cl/
AgOTf. In this transformation, an intramolecular electrophilic
addition of the tethered aryl group onto the gold(I)-activated
cyclohexa-1,3-diene followed by rearomatization and proto-
deauration produced perhydrophenanthrenes. Moreover, the
’ RESULTS AND DISCUSSION
The requisite 5-(2-arylethyl)cyclohexa-1,3-dienes 1aꢀk were
prepared starting from addition of sodium dimethylmalonate to
the (η5-cyclohexadienyl)tricarbonyliron cation salt in THF
according to literature procedures.7 Decomplexation of the
resulting complex with cerium ammonium nitrate (CAN) in
acetone at 0 °C afforded dimethyl 2-cyclohexa-2,4-dienylmalo-
nate. Treatment of the malonate with sodium hydride in THF
followed by addition of the corresponding benzylic bromide
furnished 1aꢀk in 60ꢀ70% overall yields. Seven-membered ring
substrates 12aꢀc were prepared starting from addition of
sodium dimethylmalonate to the (η5-cycloheptadienyl)tricarbo-
nyliron cation salt following the same procedure as described
above for synthesis of 1. Our study of intramolecular gold(I)-
catalyzed cyclization of cyclic aryldienes began with the parent
compound 1a (Scheme 1). Treatment of 1a with 10 mol % of
Ph3PAuCl/AgOTf in refluxing CH2Cl2 for 4 h produced di-
methyl 7,8,8a,10-tetrahydrophenanthrene-9,9(4bH)-dicarboxy-
late (2a) as the sole diastereoisomer isolated in 65% yield
(Scheme 1). Treating 1a with 10 mol % of AgOTf or 20 mol %
of TfOH or BF3 OEt2 in refluxing CH2Cl2 for 4 h failed to give
3
any tetrahydrophenanthrene ring, and 1a was recovered quanti-
tatively in each case. However, compound 2d was isolated in 30%
after stirring 1d with TfOH in refluxing toluene for 20 h. In
general, perhydrophenanthrene ring skeletons require lengthy
synthetic procedures and are constructed via intramolecular
Received: March 4, 2011
Published: April 18, 2011
r
2011 American Chemical Society
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Scheme 1
Scheme 3
Scheme 2
the newly formed carbonꢀcarbon bond. The cis relative stere-
ochemistry of the ring juncture of 4 was fixed by the aryl moiety
aligned with the face of the cyclic diene in which the tethering
chain resides. Allyl gold complex 4 underwent rearomatization
(by deprotonation) to give 5. Isomerization of the η1-allyl gold
followed by protodeauration led to 2a and regenerated the
gold(I) catalyst in the catalytic cycle. The postulated reaction
path is consistent with the reports of nucleophilic addition to
gold activated unsaturated carbonꢀcarbon bonds followed by
deprotonation/protodeauration to generate cyclized products.8a
Moreover, the proposed deprotonation/protodeauration pro-
cess involving a proton shuttle of gold species has been well
documented by Hashmi et al.8b In the current study, the diene
was activated by the cationic gold(I) complex and was then
attacked by the pendant aryl group. However, cyclohexa-1,3-
diene with an arylalkyne moiety in the tethered, for example, 6,
where the diene reacted as a nucleophile and added to the gold-
activated alkyne of 8 followed by attack of the adjacent phenyl
group at the allyl cation, afforded the perhydroacephenanthry-
lene derivative 7 (Scheme 3).5i Related gold-catalyzed cycliza-
tions of enyne-like substrates with phenyl groups attached to the
alkyne moiety, producing polycyclic systems, have been
reported.9 1H NMR studies provided the initial evidence for
support of the structural assignments of 2a. The proton at δ 2.89
as a dd, J = 12.6, 5.2 Hz, was assigned to the proton at C-8a. The
coupling constant of H4bꢀH8a (J4b8a) of 5.2 Hz agrees with the
4.4ꢀ6.0 Hz coupling constant for similarly fused cis-hydrogens
compared to the 10ꢀ11 Hz observed when these protons are
trans.10 The results of the gold(I)-catalyzed cyclization of 5-(2-
arylethyl)cyclohexa-1,3-dienes 1aꢀg to produce perhydrophe-
nanthrenes 2aꢀg are listed in Scheme 1. The relative stereo-
chemistry of products 2aꢀg was assigned as the same cis
relationship between hydrogen atoms at two adjacent stereo-
genic centers on the basis of their close chemical shift values and
similar coupling patterns of the fused protons in their 1H NMR
spectra. Electron-neutral and -rich arenes were proven to be good
substrates, as the yields of desired perhydrophenanthrenes 2aꢀg
ranged from 57% to 92% (Scheme 1). Substrates 1b bearing a
naphthyl group at the tether reacted smoothly with the catalysts
to afford the perhydrobenzo[c]phenanthrene derivative 2b in
DielsꢀAlder reaction at elevated temperature in a sealed tube.4a,c
Moreover, in most cases the DielsꢀAlder reaction of the trienes
leading to perhydrophenanthrenes proceeded in both exo and
endo cycloaddition manners to give a mixture of diastereomeric
isomers.4a,c,f The current approach to the synthesis of the cis-
fused perhydrophenanthrene derivative 2 is achieved without the
use of complex catalysts or critical reaction conditions, only
requiring 10 mol % of Ph3PAuCl/AgOTf in dichloromethane at
reflux for 4 h. The product of the relative stereochemistry as
depicted was obtained as a single diastereomer, which is derived
from 1,4-addition of the phenyl group and a hydrogen atom
across the conjugated diene.
The reaction pathwayleading to 2awas suggested in Scheme 2.
Coordination of the π-bond (C3ꢀC4) of 1a to the Au metal
center from the opposite face of the tethering chain gave the
η2-alkeneꢀgold complex 3. Anti addition of the aryl group to the
Au-alkene moiety generated the σ-allyl gold intermediate 4 with
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Scheme 4
92% isolated yield (Scheme 1). However, substrates with a
bromine atom at the phenyl ring, for example, 2h, or an
electron-withdrawing group, such as an ester or nitrile group,
for example, 2i,j, or a pyridinyl group in the tether, for example,
2k, inhibited the catalytic activity of the gold species, and the
reactions failed to give any cyclized product. An unidentified
mixture of crude oil was formed in each case. It is worthy to
mention that treatment of cyclohexa-1,3-diene and phenol with
5 mol % of Ph3PAuCl/AgOTf in refluxing CH2Cl2 for 16 h failed
to give any benzofuran derivatives.6a In addition, treatment of 1a
with a catalytic amount of AgOTf (5 mol %) in refluxing
dichloroethane (DCE) according to Youn’s protocols gave 2a
in only 28% yield.6b Structure elucidation of the perhydrophe-
nanthrene derivatives 2aꢀc was achieved by X-ray crystallogra-
phy. The cis relative stereochemistry between the fused hydrogen
atoms at the adjacent stereogenic centers further supports the
proposed reaction path suggested for the formation of the
perhydrophenanthrenes (Scheme 2).
proximal methoxy group and the olefin to the gold center of
the proposed initial product 10a would give the chelating
intermediate 10b. The similar chelating intermediates are known
in the literature.11 The postulated intermediate 10b may undergo
a sequential double bond migration by deprotonation of allylic
protons followed by a protodeauration process involving a
proton shuttle as stated previously to form 11.8b
The chemistry can be applied to synthesis of cyclohepta-
[c]phenanthrenes and cyclohepta[a]naphthalenes from seven-
membered ring substrates. Thus, arylcycloheptadienes 12a and
12b, possessing a 2-naphthyl or a 3,4-dimethoxyphenyl group in
the tether (Scheme 4), underwent cyclization smoothly using the
same reaction conditions (10 mol % of Ph3PAuCl/AgOTf in
Interestingly, with two methoxy groups at C-3 and C-5
positions of the arene, for example, 9, the cyclization led to the
conjugated perhydrophenanthrene derivative 11 in 63% yield
under the same reaction conditions. Chelation of both the
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Scheme 5
CH2Cl2 at reflux for 4 h) to provide the cyclohepta[c]phenan-
threne derivative 13a and the cyclohepta[a]naphthalene derivative
14, respectively, as the only stereoisomer in each case and in good
yield. NOESY experiments provided the initial evidence for
support of a cis relationship between the fused hydrogen atoms
of 13a. The structure 13a was further confirmed by X-ray
diffraction analysis. Interestingly, when treated with 10 mol %
of Ph3PAuCl/AgOTf in toluene at 85 °C for 40 h, compound
12a was transformed to both the cis isomer 13a and the trans
isomer 13b in a ratio of 1:3 and in a 57% total yield (Scheme 4).
In this case, the intramolecular FriedelꢀCrafts-type reaction
occurred on both faces of the cycloheptadienyl ring at higher
temperature (ca. 85 °C) and led to both cis and trans isomers.
However, treating 1a with the gold(I) catalyst in toluene at 85 °C
for 40 h gave only cis isomer 2a in 50% yield and none of the trans
isomer was detected. The structure elucidation of the trans
cyclohepta[c]phenanthrene derivative 13b was accomplished
by X-ray diffraction analysis. As expected, the electron-rich
substrate 12b underwent the intramolecular FriedelꢀCrafts-type
reaction in refluxing methylene chloride to afford the cyclohepta-
[a]naphthalene derivative 14 in 72% isolated yield. The relative
stereochemistry of 14 was assigned as the same cis relationship as
that of 13a on the basis of their close chemical shift values and the
similar coupling patterns of the proton at the C-6a position in the
1H NMR spectra.
of 15. The formation of 15 was suggested in Scheme 5.
Coordination of the alkene of the initial formed 13c to the Au
metal center from the exo face produced the η2-gold-alkene 16.
As stated for compound 10a, chelation of both the olefin and the
proximal methoxy group to the gold center of 13c would form
the postulated intermediate 16. The ester group would attack at
the Au-alkene moiety from the endo face to give the tetracyclic
ring skeleton 17, containing an η1-alkylgold bond at the benzylic
position. The stereoselectivity outcome is consistent with anti
addition of nucleophiles to gold(I)ꢀalkene complexes known in
the literature.5h The postulated intermediate 17 underwent
protodeauration and demethylation to afford 15.
In conclusion, a gold-catalyzed 1,4-hydroarylation of unacti-
vated cyclic 5-(2-arylethyl)-1,3-dienes has been successfully
developed. The aryl group added to the terminal position of
the diene in the presence of a catalytic amount of Ph3PAuCl/
AgOTf followed by protodemetalation to afford perhydrophe-
nanthrenes and perhydrocyclohepta[a]naphthalenes. The trans-
formation is characterized by its efficiency, the mild conditions
employed, and the easy formation of the desired carbotricycles in
good yields with cis diastereoselectivity at the fused carbons from
readily available starting substrates. The trans isomer of the
perhydrocyclohepta[c]phenanthrene derivative can be obtained
when treated with a naphthyl-tethered cycloheptadienyl sub-
strate at elevated temperature.
Interestingly, using the same reaction conditions, we were able
to construct the tetracyclic ring skeleton, such as 15, via the initial
hydroarylation followed by intramolecular hydroalkoxylation of a
tethered methyl ester and a hydrogen atom to the double bond of
the cycloheptene ring. Thus, treatment of 12c with 10 mol % of
Ph3PAuCl/AgOTf in CH2Cl2 at reflux for 4 h furnished the
carbotetracycle 15 in 85% isolated yield (Scheme 4). The
product of the relative stereochemistry as depicted was obtained
as a single diastereomer. NOESY (nuclear Overhauser enhance-
ment spectroscopy) experiments and X-ray diffraction analysis
provided the initial evidence for support of all syn relationships
among hydrogen atoms at three contiguous stereogenic centers
’ EXPERIMENTAL SECTION
General Considerations. All reactions were performed in oven-
dried glassware under a nitrogen atmosphere unless otherwise indicated.
Anhydrous solvents or reaction mixtures were transferred via an oven-
dried syringe or cannula. Methylene chloride was predried by molecular
sieves and then by passing through an Al2O3 column.12 Flash column
chromatography followed the method of Still,13 using the indicated
solvents. 1H nuclear magnetic resonance (NMR) spectra were obtained
with 400 and 500 MHz spectrometers. The chemical shifts are reported
in parts per million with either tetramethylsilane (0.00 ppm) or CDCl3
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(7.26 ppm) as internal standard. 13C NMR spectra were recorded with a
100 MHz spectrometer with CDCl3 (77.0 ppm) as the internal standard.
Mass spectra were acquired on a spectrometer at an ionization potential
of 70 eV and were reported as mass/charge (m/e) with percent relative
abundance. High- resolution mass spectra were obtained with a double-
focusing mass spectrometer.
General Procedure for Gold(I)-Catalyzed Intramolecular
Hydroarylation of Cyclic 5-(2-Arylethyl)-1,3-dienes. To an
oven-dried 50 mL round-bottom flask equipped with a stirrer bar and
capped with a rubber septum was added AgOTf (41.6 mg, 0.16 mmol).
The apparatus was evacuated (oil pump) and filled with nitrogen three
times. To the reaction mixture were then added via syringe compound
1a (0.49 g, 1.63 mmol) and PPh3AuCl (0.08 g, 0.16 mmol) in 30 mL of
CH2Cl2. The resulting mixture was stirred at reflux for 4 h. The resulting
reaction mixture was filtered through a bed of Celite. The filtrate was
concentrated in vacuo to give the crude mixture.
J = 12.4, 5.4 Hz, 1 H); 13C NMR (100 MHz, CDCl3) δ 171.0, 170.8,
158.2, 138.7, 130.0, 128.6, 127.5, 123.8, 112.8, 111.9, 57.9, 55.1, 52.7,
52.7, 37.0, 35.8, 29.7, 25.6, 21.5; MS (EI) m/e (%) 330.2 (Mþ, 17), 271.2
(17), 270.2 (42), 239.2 (15), 225.1 (12), 211.2 (100), 210.1 (30), 209.1
(14), 197.1 (10), 196.1 (10), 185.1 (11), 184.1 (11), 179.1 (16), 165.1
(14), 121.1 (35); HRMS (EI) m/e calcd for C19H22O5 330.1469, found
330.1467.
(()-(4bS,8aR)-Dimethyl 3-Phenyl-7,8,8a,10-tetrahydro-
phenanthrene-9,9(4bH)-dicarboxylate (2d). The crude mixture
obtained from intramolecular hydroarylation of 1d (0.68 g, 1.80 mmol)
was purified by flash column chromatography (silica gel, gradient
elution: 5%ꢀ10% ethyl acetate/hexanes) to give 2d (0.62 g, 1.65 mmol,
92%) as a yellow liquid: IR (CH2Cl2) 3031, 2953, 1734, 1647, 1601,
1485, 1435, 1261, 1177, 1046, 970 cmꢀ1; 1H NMR (500 MHz, CDCl3)
δ 7.58ꢀ7.53 (m, 2 H), 7.52 (s, 1 H), 7.43 (t, J = 6.1 Hz, 2 H), 7.37ꢀ7.31
(m, 2 H), 7.23 (d, J = 6.4 Hz, 1 H), 6.34 (m, 1 H), 5.86 (m, 1 H), 3.82 (s,
3 H), 3.80 (m, 1 H), 3.68 (s, 3 H), 3.50 (d, J = 13.8 Hz, 1 H), 3.36 (d, J =
13.8 Hz, 1 H), 2.98 (dd, J = 10.0, 4.4 Hz, 1 H), 2.20 (m, 1 H), 2.10 (td, J =
14.2, 4.0 Hz, 1 H), 1.58 (m, 1 H), 1.42 (qd, J = 9.9, 4.3 Hz, 1 H); 13C
NMR (100 MHz, CDCl3) δ 170.9, 170.7, 141.2, 139.4, 137.8, 130.8,
129.4, 128.6, 128.5, 127.4, 126.9, 126.55, 124.5, 57.7, 52.7, 52.7, 37.1,
35.6, 30.2, 25.6, 21.4; MS (EI) m/e (%) 376.3 (Mþ, 0.8), 317.2 (15),
316.2 (37), 298.2 (14), 285.2 (11), 258.2 (22), 257.2 (100), 255.2 (10),
241.2 (14), 239.2 (12), 238.2 (26), 215.1 (15), 207.1 (12), 202.1 (11),
179.1 (13), 178.1 (16), 167.1 (44), 165.1 (22), 152.1 (12); HRMS (EI)
m/e calcd for C24H24O4 376.1666, found 376.1674.
(()-(4bS,8aR)-Dimethyl 2-Methoxy-7,8,8a,10-tetrahydro-
phenanthrene-9,9(4bH)-dicarboxylate (2e). The crude mixture
obtained from intramolecular hydroarylation of 1e (0.62 g, 1.87 mmol)
was purified by flash column chromatography (silica gel, gradient
elution: 5%ꢀ10% ethyl acetate/hexanes) to give 2e (0.37 g, 1.10 mmol,
60%) as a yellow liquid: IR (CH2Cl2) 3435, 2954, 1731, 1638, 1502,
1434, 1257, 1036, 733 cmꢀ1; 1H NMR (400 MHz, CDCl3) δ 7.16 (d, J =
8.6 Hz, 1 H), 6.72 (d, J = 7.6 Hz, 1 H), 6.65 (s, 1 H), 6.20 (m, 1 H), 5.79
(m, 1 H), 3.78 (s, 3 H), 3.76 (s, 3 H), 3.64 (s, 3 H), 3.60 (s, 1 H), 3.38 (d,
J = 17.2 Hz, 1 H), 3.25 (d, J = 17.2 Hz, 1 H), 2.84 (dd, J = 12.3, 4.7 Hz, 1
H), 2.15 (m, 1 H), 2.03 (m, 1 H), 1.50 (m, 1 H), 1.33 (qd, J = 12.3, 5.4
Hz, 1 H); 13C NMR (100 MHz, CDCl3) δ 170.9, 170.7, 157.3, 133.0,
129.7, 129.0, 128.7, 127.05, 113.4, 113.0, 57.8, 55.0, 52.8, 52.7, 37.2, 34.9,
30.7, 25.6, 21.3; MS (EI) m/e (%) 330.3 (Mþ, 35), 285.2 (10), 271.2
(15), 270.2 (26), 253.2 (13), 239.2 (18), 233.1 (11), 225.1 (13), 212.2
(19), 211.2 (100), 210.1 (14), 209.1 (14), 201.1 (10), 197.1 (10), 196.1
(10), 185.1 (11), 179.1 (11), 171.1 (10), 165.1 (15), 121.1 (13); HRMS
(EI) m/e calcd for C19H22O5 330.1470, found 330.1467.
(()-(4bS,8aR)-Dimethyl 7,8,8a,10-Tetrahydrophenan-
threne-9,9(4bH)-dicarboxylate (2a). The crude mixture obtained
from intramolecular hydroarylation of 1a (0.49 g, 1.63 mmol) was
purified by flash column chromatography (silica gel, gradient elution:
5%ꢀ10% ethyl acetate/hexanes) to give 2a (0.28 g, 0.93 mmol, 57%) as
a white solid: mp 82ꢀ83 °C; IR (CH2Cl2) 2952, 1732, 1647, 1493,
1
1432, 1308, 1176, 1135, 1043 cmꢀ1; H NMR (500 MHz, CDCl3) δ
7.26 (d, J = 10.6 Hz, 1 H), 7.16ꢀ7.07 (m, 3 H), 6.23 (m, 1 H), 5.81 (m,
1 H), 3.78 (s, 3 H), 3.70 (m, 1 H), 3.63 (s, 3 H), 3.41 (d, J = 17.2 Hz, 1 H),
3.29 (d, J = 17.2 Hz, 1 H), 2.89 (dd, J = 12.6, 5.2 Hz, 1 H), 2.16 (m, 1 H),
2.05 (dt, J = 17.8, 5.2 Hz, 1 H), 1.51 (m, 1 H), 1.34 (qd, J = 12.5, 5.4 Hz,
1 H); 13C NMR (100 MHz, CDCl3) δ 171.0, 170.8, 137.5, 131.7, 129.1,
128.8, 127.8, 127.3, 126.5, 125.6, 52.8, 52.7, 57.8, 37.1, 35.6, 30.4, 25.6,
21.5; MS (EI) m/e (%) 300.2 (Mþ, 16), 240.2 (62), 181.1 (100), 178.1
(12), 167.1 (10), 166.1 (21), 165.1 (28), 153.1 (10), 141.1 (11); HRMS
(EI) m/e calcd for C18H20O4 300.1370, found 300.1362. Crystals
suitable for X-ray diffraction analysis were grown from CH2Cl2 and
hexanes.
(()-(4aR,12cS)-Dimethyl 4,4a,6,12c-Tetrahydrobenzo[c]-
phenanthrene-5,5(3H)-dicarboxylate (2b). The crude mixture
obtained from intramolecular hydroarylation of 1b (0.42 g, 1.19 mmol)
was purified by flash column chromatography (silica gel, gradient
elution: 5%ꢀ10% ethyl acetate/hexanes) to give 2b (0.38 g, 1.09 mmol,
91%) as a white solid: mp 146ꢀ147 °C; IR (CH2Cl2) 3429, 1734, 1638,
1432, 1241 cmꢀ1; 1H NMR (400 MHz, CDCl3) δ 8.01 (d, J = 8.4 Hz,
1 H), 7.76 (d, J = 7.9 Hz, 1 H), 7.57 (d, J = 8.3 Hz, 1 H), 7.45 (m, 1 H),
7.39 (m, 1 H), 7.18 (d, J = 8.4 Hz, 1 H), 6.15 (br d, J = 7.6 Hz, 1 H), 5.79
(m, 1 H), 4.61 (m, 1 H), 3.77 (s, 3 H), 3.57 (d, J = 16.4 Hz, 1 H), 3.42 (s,
3 H), 3.34 (d, J = 16.4 Hz, 1 H), 3.24 (m, 1 H), 2.11ꢀ2.05 (m, 2 H),
1.47ꢀ1.59 (m, 2 H); 13C NMR (100 MHz, CDCl3) δ 171.2, 170.5,
133.4, 133.3, 131.2, 130.2, 129.5, 128.7, 1278.0, 127.5, 126.4,125.5,
124.5, 124.3, 58.8, 52.7, 52.5, 37.2, 34.6, 32.2, 23.8, 23.2; MS (EI) m/e
(%) 350.2 (Mþ, 49), 351.3 (10), 291.2 (12), 290.2 (33), 259.2 (14),
231.2 (100), 230.2 (23), 229.2 (14), 216.1 (17), 215.1 (21), 205.1 (11),
203.1 (14), 202.1 (17), 178.1 (10), 141.1 (15); HRMS (EI) m/e calcd
for C22H22O4 350.1520, found 350.1518. Crystals suitable for X-ray
diffraction analysis were grown from CH2Cl2 and hexanes.
(()-(4bS,8aR)-Dimethyl 1-Methoxy-7,8,8a,10-tetrahydro-
phenanthrene-9,9(4bH)-dicarboxylate (2f). The crude mixture
obtained from intramolecular hydroarylation of 1f (0.60 g, 1.81 mmol)
was purified by flash column chromatography (silica gel, gradient
elution: 5%ꢀ10% ethyl acetate/hexanes) to give 2f (0.38 g, 1.14 mmol,
63%) as a yellow liquid: IR (CH2Cl2) 2951, 1734, 1583, 1467, 1436,
1
1259, 1235, 1197, 1104, 1043 cmꢀ1; H NMR (400 MHz, CDCl3) δ
7.13 (t, J = 8.0 Hz, 1 H), 6.87 (d, J = 7.9 Hz, 1 H), 6.63 (d, J = 8.1 Hz,
1 H), 6.21 (m, 1 H), 5.79 (m, 1 H), 3.81 (m, 3 H), 3.77 (m, 3 H), 3.67 (m,
1 H), 3.62 (s, 3 H), 3.59 (d, J = 18.1 Hz, 1 H), 2.91 (d, J = 18.1 Hz,
1 H), 2.84 (m, 1 H), 2.15 (m, 1 H), 2.01 (m, 1 H), 1.53 (m, 1 H), 1.31 (qd,
J = 12.5, 5.5 Hz, 1 H); 13C NMR (100 MHz, CDCl3) δ 171.22, 171.08,
157.04, 138.79, 129.0, 127.4, 126.8, 121.0, 119.8, 106.8, 57.2, 55.3, 52.8,
36.7, 36.4, 35.5, 25.7, 24.5, 21.28; MS (EI) m/e (%) 330.1 (Mþ, 0.1),
271.2 (10), 270.2 (35), 211.1 (100), 210.1 (33), 179.1 (15), 165.1 (14);
HRMS (EI) m/e calcd for C19H22O5 330.1460, found 330.1468.
(()-(4bS,8aR)-Dimethyl 3-Methoxy-7,8,8a,10-tetrahydro-
phenanthrene-9,9(4bH)-dicarboxylate (2c). The crude mixture
obtained from intramolecular hydroarylation of 1c (0.50 g, 1.51 mmol)
was purified by flash column chromatography (silica gel, gradient elution:
5%ꢀ10% ethyl acetate/hexanes) to give 2c (0.32 g, 0.94 mmol, 63%) as
a white solid: mp 102ꢀ103 °C; IR (CH2Cl2) 3439, 1731, 1645, 1500,
1
1435, 1233, 1036 cmꢀ1; H NMR (400 MHz, CDCl3) δ 7.03 (d, J =
8.4 Hz, 1 H), 6.79 (s, 1 H), 6.67 (dd, J = 8.2 Hz, 8.4 Hz, 1 H), 6.20 (m, 1 H),
5.81 (m, 1 H), 3.77 (s, 3 H), 3.75 (s, 3 H), 3.67 (m, 1 H), 3.63 (s, 3 H),
3.34 (d, J = 16.9 Hz, 1 H), 3.21 (d, J = 16.9 Hz, 1 H), 2.89ꢀ2.85 (dd, J =
12.4, 5.2 Hz, 1 H), 2.13 (m, 1 H), 2.05 (m, 1 H), 1.50 (m, 1 H), 1.33 (qd,
(()-(4bS,8aR)-Dimethyl 2,3-Dimethoxy-7,8,8a,10-tetra-
hydrophenanthrene-9,9(4bH)-dicarboxylate (2g). The crude
mixture obtained from intramolecular hydroarylation of 1g (0.18 g,
0.5 mmol) was purified by flash column chromatography (silica gel,
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The Journal of Organic Chemistry
ARTICLE
gradient elution: 5%ꢀ10% ethyl acetate/hexanes) to give 2g (0.12 g,
0.34 mmol, 68%) as a yellow liquid: 1H NMR (400 MHz, CDCl3) δ 6.72
(s, 1 H), 6.60 (s, 1 H), 6.19 (m, 1 H), 5.83 (m, 1 H), 3.84 (s, 3 H), 3.83 (s,
3 H), 3.78 (s, 3 H), 3.65 (s, 3 H), 3.63 (s, 1 H), 3.27 (m, 2 H), 2.87 (m,
(EI) m/e calcd for C23H24O4 364.1675, found 364.1674. Crystals
suitable for X-ray diffraction analysis were grown from CH2Cl2 and
hexanes.
(()-(6aR,11aS)-Dimethyl 2,3-Dimethoxy-6a,7,8,9-tetrahy-
dro-5H-cyclohepta[a]naphthalene-6,6(11aH)-dicarboxylate
(14). The crude mixture obtained from intramolecular hydroarylation of
12b (0.19 g, 0.5 mmol) was purified by flash column chromatography
(silica gel, gradient elution: 5%ꢀ10% ethyl acetate/hexanes) to give 14
(0.13 g, 0.36 mmol, 72%) as a yellow liquid: IR (CH2Cl2) 3011, 1731,
1 H), 2.15 (m, 1 H), 2.07 (m, 1 H), 1.50 (m, 1 H), 1.25 (m, 1 H); 13
C
NMR (400 MHz, CDCl3) δ 171.0, 170.8, 147.9, 147.2, 129.4, 128.8,
127.5, 123.8, 111.6, 110.5, 58.0, 55.8, 52.8, 37.0, 35.3, 30.9, 30.0, 25.6,
21.4; IR (CH2Cl2) 1731, 1660, 1505, 1455, 1242, 1216 cmꢀ1; MS (EI)
m/e (%) 360.3 (Mþ, 70), 300.3 (26), 269.2 (21), 242.2 (17), 241.2
(100), 59.1 (13); HRMS (EI) m/e calcd for C20H24O6 360.1579, found
360.1573.
1
1608, 1505, 1434, 1212, 1142 cmꢀ1; H NMR (400 MHz, CDCl3) δ
6.73 (s, 1 H), 6.65 (s, 1 H), 5.96 (m, 2 H), 3.85 (s, 3 H), 3.81 (s, 3 H),
3.75 (s, 3 H), 3.71 (s, 3 H), 3.65 (m, 1 H), 3.38 (d, J = 17.2 Hz, 1 H), 3.22
(d, J = 17.3 Hz, 1 H), 2.89 (m, 1 H), 2.22 (m, 1 H), 1.85 (m, 1 H),
1.72ꢀ1.65 (m, 2 H), 1.51ꢀ1.39 (m, 2 H); 13C NMR (100 MHz,
CDCl3) δ 171.6, 171.1, 147.5, 147.3, 133.3, 131.2, 129.2, 125.4, 111.2,
110.5, 59.2, 55.9, 55.8, 52.9, 52.6, 41.2, 40.2, 31.4, 28.8, 28.0, 26.0; MS
(EI) m/e (%) 374.2 (Mþ, 52), 314.1 (46), 283.1 (41), 256.1 (20), 255.1
(100), 227.1 (16), 84 (15.5); HRMS (EI) m/e calcd for C21H26O6
374.1740, found 374.1739.
(()-(6S,6aR,11S,11aS)-Methyl 1,3-Dimethoxy-13-oxo-6,6a,7,
8,9,10,11,11a-octahydro-5H-11,6-(epoxymethano)cyclohepta-
[c]naphthalene-6-carboxylate (15). The crude mixture obtained
from intramolecular hydroarylation of 12c (0.19 g, 0.5 mmol) was
purified by flash column chromatography (silica gel, gradient elution:
5%ꢀ10% ethyl acetate/hexanes) to give 15 (0.15 g, 0.42 mmol, 85%) as
a white solid: mp 187ꢀ188 °C; IR (CH2Cl2) 3402, 1727, 1643, 1462,
1250, 1147 cmꢀ1; 1H NMR (400 MHz, CDCl3) δ 6.31 (d, J = 2.0 Hz,
1 H), 6.21 (d, J = 2.0 Hz, 1 H), 4.55 (s, 1 H), 3.81(s, 3 H), 3.80 (s, 3 H),
3.76 (s, 3 H), 3.72 (d, J = 17.2 Hz, 1 H), 3.55 (d, J = 3.2 Hz, 1 H), 3.21 (d,
J = 17.2 Hz, 1 H), 2.48 (m, 1 H, H-6), 2.22 (m, 1 H), 1.97ꢀ1.62 (m,
7 H); 13C NMR (100 MHz, CDCl3) δ 172.0, 171.6, 159.6, 156.8, 134.2,
120.5, 103.4, 97.1, 88.5, 55.5, 55.4, 54.4, 52.4, 40.4, 28.8, 33.0, 32.7, 32.6,
26.5, 22.6; MS (EI) m/e (%) 360.2 (Mþ, 84), 301.2 (70), 273.2 (39),
257.2 (57), 255.2 (21), 248.2 (25), 247.1 (100), 245.1 (25), 215.1 (41),
203.1 (19), 201.1 (40), 189.1 (34), 188.1 (54), 59 (24); HRMS (EI) m/e
calcd for C20H24O6 360.1581, found 360.1573. Crystals suitable for
X-ray diffraction analysis were grown from CH2Cl2 and hexanes.
Dimethyl 2,4-Dimethoxy-5,6,7,8-tetrahydrophenanthrene-
9,9(10H)-dicarboxylate (11). The crude mixture obtained from
intramolecular hydroarylation of 9 (0.18 g, 0.5 mmol) was purified by
flash column chromatography (silica gel, gradient elution: 5%ꢀ10%
ethyl acetate/hexanes) to give 11 (0.12 g, 0.34 mmol, 68%) as a white
solid: mp 148ꢀ150 °C; IR (CH2Cl2) 3372, 2100, 1732, 1644, 1434,
1230 cmꢀ1; 1H NMR (400 MHz, CDCl3) δ 6.34 (s, 1 H), 6.31 (s, 1 H),
3.79 (s, 3 H), 3.74 (s, 3 H), 3.68 (s, 6 H), 3.27 (s, 2 H), 2.64 (m, 2 H),
2.24 (m, 2 H), 1.7 (m, 2 H), 1.63 (m, 2 H); 13C NMR (400 MHz,
CDCl3) δ 171.8, 159.0, 157.5, 136.0, 131.4, 127.9, 117.9, 104.8, 98.2,
59.5, 55.3, 55.1, 52.8, 37.6, 29.9, 27.5, 23.2, 22.7; MS (EI) m/e (%) 360.3
(Mþ, 58), 301.2 (100), 269.2 (70), 242.2 (62), 241.2 (33), 227.2 (11),
226.2 (12); HRMS (EI) m/e calcd for C20H24O6 360.1564, found
360.1573. Crystals suitable for X-ray diffraction analysis were grown
from CH2Cl2 and hexanes.
(()-(8aR,13aS)-Dimethyl 8a,9,10,11-Tetrahydro-7H-cyclo-
hepta[c]phenanthrene-8,8(13aH)-dicarboxylate (13a). The
crude mixture obtained from intramolecular hydroarylation of 12a
(0.45 g, 1.25 mmol) was purified by flash column chromatography
(silica gel, gradient elution: 5%ꢀ10% ethyl acetate/hexanes) to give 13a
(0.28 g, 0.77 mmol, 63%) as a white solid: mp 136ꢀ137 °C; IR (CH2Cl2)
3433, 1729, 1638, 1433, 1243, 1066 cmꢀ1; 1H NMR (500 MHz, CDCl3)
δ 7.92 (d, J = 8.4 Hz, 1 H), 7.79 (d, J = 7.9 Hz, 1 H), 7.66 (d, J = 8.4 Hz,
1 H), 7.46 (d, J = 7.1 Hz, 1 H), 7.44 (d, J = 7.1 Hz, 1 H), 7.20 (d, J = 8.4Hz,
1 H), 5.52 (m, 1 H), 5.09 (m, 1 H), 4.80 (m, 1 H), 3.74 (s, 3 H), 3.60 (s, 3
H), 3.57 (d, J = 16.3 Hz, 1 H), 3.15 (d, J = 16.3 Hz, 1 H), 2.98 (dd, J =
15.3, 8.4 Hz, 1 H), 2.60 (d, J = 15.3 Hz, 1 H), 2.27 (m, 3 H), 2.00 (m,
1 H), 1.79 (m, 1 H); 13C NMR (100 MHz, CDCl3) δ 172.5, 171.3,
133.5, 132.0, 131.7, 130.9, 128.6, 128.1, 127.0, 126.8, 125.9, 124.8, 124.1,
56.6, 52.5, 51.9, 43.3, 38.7, 35.0, 29.6, 25.6, 21.5; MS (EI) m/e (%) 364.3
(Mþ, 99), 305.2 (21), 304.2 (63), 273.2 (21), 245.2 (100), 244.2 (23),
217.1 (31), 216.1 (20), 215.1 (26), 205.1 (21), 203.1 (28), 202.1 (29),
191.1 (28), 178.1 (28) ; HRMS (EI) m/e calcd for C23H24O4 364.1675,
found 364.1674. Crystals suitable for X-ray diffraction analysis were
grown from CH2Cl2 and hexanes.
’ ASSOCIATED CONTENT
Supporting Information. 1H NMR and 13C NMR spec-
S
b
tra of compounds 2aꢀg, 11, 13a,b, 14, and 15 and X-ray
crystallographic information files for compounds 2a,b, 11, 13a,
b, and 15. This material is available free of charge via the Internet
at http://pubs.acs.org.
’ AUTHOR INFORMATION
(()-(8aS,13aS)-Dimethyl 8a,9,10,11-Tetrahydro-7H-cyclo-
hepta[c]phenanthrene-8,8(13aH)-dicarboxylate (13b). The
crude mixture obtained from intramolecular hydroarylation of 12a
(0.45 g, 1.25 mmol) at 85 °C in toluene for 4 h was purified by flash
column chromatography (silica gel, gradient elution: 5%ꢀ10% ethyl
acetate/hexanes) to give 13a (0.065 g, 0.18 mmol, 14%) and 13b (0.20 g,
0.53 mmol, 42%) both as white solids. 13b: mp 137ꢀ139 °C; IR
Corresponding Author
*Fax: 886-2-29324249. E-mail: cheyeh@ntnu.edu.tw.
’ ACKNOWLEDGMENT
1
(CH2Cl2) 3433, 1729, 1638, 1433, 1243, 1066 cmꢀ1; H NMR (400
This work was supported by grants from the National Science
Council (NSC 98-2119-M-003-004-MY3 and NSC 98-2119-M-
003-001-MY2) and National Taiwan Normal University.
MHz, CDCl3) δ 7.87 (d, J = 8.2 Hz, 1 H), 7.77 (m, 1 H), 7.61 (d, J = 8.3
Hz, 1 H), 7.48ꢀ7.38 (m, 2 H), 7.15 (d, J = 8.4 Hz, 1 H), 5.89 (m, 1 H),
5.57 (m, 1 H), 4.55 (m, 1 H), 3.81 (s, 3 H), 3.47 (d, J = 15.4 Hz, 1 H),
3.39 (d, J = 17.9 Hz, 1 H), 3.36 (s, 3 H), 2.65ꢀ2.46 (m, 2 H), 2.41 (m,
1 H), 2.28 (m, 1 H), 2.05ꢀ1.93 (m, 2 H), 1.51 (m, 1 H); 13C NMR (100
MHz, CDCl3) δ 172.8, 170.2, 140.1, 134.9, 133.4, 131.3, 131.1, 130.9,
128.5, 127.2, 126.8, 125.8, 125.0, 124.9, 59.6, 52.6, 51.8, 47.4, 40.4, 40.0,
34.4, 28.1, 26.8; MS (EI) m/e (%) 364.3 (Mþ, 99), 305.2 (21), 304.2
(63), 273.2 (21), 245.2 (100), 244.2 (23), 217.1 (31), 216.1 (20), 215.1
(26), 205.1 (21), 203.1 (28), 202.1 (29), 191.1 (28), 178.1 (28); HRMS
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