Regioselective synthesis of substituted naphthalenes and phenanthrenes by FeCl3-promoted annulation of aryl and naphthyl acetaldehydes with alkynes

Article abstract of DOI:10.1016/j.tet.2012.07.007

The FeCl₃-promoted annulation reaction of aryl acetaldehydes with alkynes has been established, which provides a new and versatile straightforward procedure for the regioselective synthesis of mono-, di-, and polysubstituted naphthalenes under mild conditions. Interestingly, the present catalytic system not only differentiates between internal and terminal alkynes but also shows unprecedented complete Me₃SiOH elimination selectivity for silyl alkyne substrates. Furthermore, the synthesis of a series of substituted phenanthrenes via reactions of nathphyl acetaldehydes with internal alkynes is also achieved for the first time in good yields with excellent regioselectivity.

Full text of DOI:10.1016/j.tet.2012.07.007

Tetrahedron 68 (2012) 7960e7965
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Regioselective synthesis of substituted naphthalenes and phenanthrenes by
FeCl3-promoted annulation of aryl and naphthyl acetaldehydes with alkynes
,b,
Xiuli Bu a, Longcheng Hong a, Ruiting Liu a, Jianquan Hong a, Zhengxing Zhang a, Xigeng Zhou a
*
a Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433, People’s Republic of China
b State Key Laboratory of Organometallic Chemistry, Shanghai 200032, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
The FeCl3-promoted annulation reaction of aryl acetaldehydes with alkynes has been established, which
provides a new and versatile straightforward procedure for the regioselective synthesis of mono-, di-,
and polysubstituted naphthalenes under mild conditions. Interestingly, the present catalytic system not
only differentiates between internal and terminal alkynes but also shows unprecedented complete
Me3SiOH elimination selectivity for silyl alkyne substrates. Furthermore, the synthesis of a series of
substituted phenanthrenes via reactions of nathphyl acetaldehydes with internal alkynes is also achieved
for the first time in good yields with excellent regioselectivity.
Received 16 April 2012
Received in revised form 22 June 2012
Accepted 3 July 2012
Available online 11 July 2012
Keywords:
o-(1-Alkynyl)benzoates
Disulfides
Ó 2012 Elsevier Ltd. All rights reserved.
Sulfoesterification
Bicyclization
Iron (III) chloride
1. Introduction
The development of alternative catalytic methods for the acti-
vation of chemical bonds using iron salts in place of noble metal
The development of new naphthalene- and phenanthrene-
based structures and new methods for their construction has
been of longstanding importance in organic chemistry because of
the frequent existence of such moieties in biologically active com-
pounds as well as their role as valuable synthetic intermediates.1,2
Over the past several years, the metal-promoted benzannulation
of aryl acetaldehydes with arylalkynes has emerged as an efficient
and regioselective method for the construction of substituted
naphthalene derivatives.3 These transformations effect tandem
coupling and cyclization in 1-step with water as the only waste
material. Therefore, in principle, it is an efficient and simple strat-
egy and can be considered as a ‘greener’ approach than the tradi-
tional procedures. Although several efficient Lewis acid catalysts,
such as TiCl4,3b GaCl3,3a and AuCl3/AgSbF6,3c have been developed
in this area, a more diverse selection of catalytic systems is still
highly desirable. In particular the development of the catalysts that
are complementary to the previously reported catalytic systems,
with some behaving similarly, but others displaying behavior un-
precedented in selectivity, is essential. In addition, the question of
whether or not the corresponding phenanthrenes could also be
achieved via similar reactions is still an open issue.
species is currently attracting considerable attention from both
academic and industrial researchers due to their low price, com-
mercial accessibility, environmentally friendly character, and ex-
ceptional reactivity.4 Iron (III) chloride has been utilized in a wide
variety of organic reactions, such as reduction of nitroarenes to
anilines,5 activation of C]O,6 C]N,7 C^C,8 CeH(X),9 and CeO10
bonds, and cross-coupling reactions.4a,11 In seeking to further
broaden the scope of metal-catalyzed benzannulations of aryl ac-
etaldehydes with arylalkynes, we were intrigued by the possibility
that an iron-based species might offer a valuable alternative to
other Lewis acid catalysts in terms of enhanced chemoselectivity.
Herein we describe a new and selective FeCl3-promoted synthesis
of substituted naphthalenes from aryl acetaldehydes and internal
alkynes under mild and convenient reaction condition, including
an unprecedented extension to substituted phenanthrenes.
2. Results and discussion
In our initial experiments phenylacetaldehyde (1a) and diphe-
nylacetylene (2a) were chosen as model substrates for exploring
the optimum reaction conditions. As shown in Table 1, the most
promising results were obtained in the presence of FeCl3. To opti-
mize conditions with FeCl3 as a Lewis acid, we examined the effect
of other reaction parameters. Different solvents were examined
first (Table 1, entries 1e7). In general, use of coordinated solvents
* Corresponding author. Tel./fax: þ86 21 65643769; e-mail address: xgzhou@
fudan.edu.cn (X. Zhou).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.07.007

X. Bu et al. / Tetrahedron 68 (2012) 7960e7965
7961
Table 2
Synthesis of substituted naphthalene derivatives via reaction of aldehydes with
Table 1
internal alkynesa
Optimization of the reaction conditionsa
Entry
Additive (equiv)
Solvent
Time (h)
Yield (%)b
Entry
1
2
R2
R3
3
Yield (%)b
73(63c)
76
69
73
79
79
61
81
86
76
81
73
1
2
3
4
5
6
7
8
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (0.5)
FeCl3 (0.1)
FeCl3 (1.2)
Fe(acac)3 (1.0)
FeCl2 (1.0)
FeCl3$6H2O
InCl3 (1.0)
DCM
CH3NO2
Toluene
THF
CH3CN
DME
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
7
28
28
28
4
3
2
24
14
2
24
26
15
NR
NR
NR
61
12
Trace
73
NR
NR
NR
12
NR
NR
NR
NR
61c
25c
1
2
3
4
5
6
7
8
1a
1a
1a
1a
1b
1b
1b
1b
1b
1c
1c
1c
1c
2a
2b
2c
2d
2a
2b
2c
2d
2e
2a
2b
2c
2d
Ph
Ph
Ph
3aa
3ab
3ac
3ad
3ba
3bb
3bc
3bd
3be
3ca
3cb
3cc
3cd
p-CH3OC6H4
p-CH3C6H4
Ph
p-CH3C6H4
CH2CH3
Ph
Ph
p-CH3OC6H4
p-CH3C6H4
Ph
Ph
Ph
p-CH3OC6H4
p-CH3C6H4
Ph
Ph
p-CH3C6H4
CH2CH3
CH3
Ph
Ph
9
9
10
11
12
13
14
15
16
17
18
19
20
10
11
12
13
2
13
12
2
2
2
2
2
16
14
p-CH3C6H4
CH2CH3
76
a
BiCl3 (1.0)
YCl3 (1.0)
Reaction conditions: Aldehyde (1.2 equiv), alkyne (1.0 equiv), FeCl3 (1.2 equiv),
1,2-DCE (3 mL), rt (18e26 ꢀC), 2 h.
b
Y(OTf)3 (1.0)
TsOH$H2O (0.2)
FeCl3 (0.4)/YCl3 (0.2)
Isolated yield.
Carried out in 8 mmol scale.
c
ꢀ
FeCl3 (0.5)/4 A MS
DCE
a
Reaction conditions: Phenylacetaldehyde (0.34 mmol), diphenylacetylene
(Table 2, entries 1, 5, and 10). The annulation reactions of electron-
rich (entries 2, 3, 6, 7, 11, 12) and electron-neutral (entries 1, 5, 10)
aryl acetylenes proceeded smoothly, and alkylated acetylenes 2d
and 2e also afforded the naphthalene products in good yields (entry
4, 8, 9, 13). However, alkyne bearing the strong electron-
withdrawing substituents, such as dimethyl acetylenedicarbox-
ylate, was inefficient substrate.
(0.28 mmol), solvent (3 mL), rt (18e26 ꢀC).
b
Isolated yield.
Carried out at 50 ꢀC.
c
(e.g., THF, DME) tends to shut down the reacting system, and
non-coordinated solvents (DCM, toluene) were also ineffective,
although small amounts of 3aa were occasionally observed. 3aa
was obtained in 61% yield when 1,2-dichloroethane (1,2-DCE) was
used as solvent. We found that the stoichiometric ratio of FeCl3 and
substrates had a large impact on the yield of the desired product.
When FeCl3 was reduced to 10 mol %, only trace amount of 3aa
could be detected along with recovery of the starting material al-
kyne (Table 1, entry 9). Best yield was obtained when 1.2 equiv of
FeCl3 was applied (Table 1, entry 10). To further improve the yields
in this transformation, the effect of metal source was systematically
examined. It was discovered that use of FeCl2, Fe(acac)3 or
FeCl3$6H2O in place of FeCl3 fails to provide the desired product
(Table 1, entries 11e13). It indicates that the coordination of Fe3þ to
H2O, which is formed during the reaction might prevent the an-
nulation to occur. Moreover, treatment of a mixture of 1a and 2a
with InCl3 in DCE gave 3aa only in low yield (Table 1, entry 14).
Other metals tested showed no activity for the annulation (Table 1,
entries 15e17). In addition, only starting materials were recovered
when FeCl3 was replaced by a Bronsted acid, such as TsOH$H2O
(Table 1, entry 18). Noticeably, FeCl3 can be decreased to a catalytic
Significantly, for the asymmetrically internal acetylenes bearing
different substituents at 1- and 2-positions, only one isomer was
obtained, indicating that these transformations allow for synthesis
of a variety of di- and poly-substituted naphthalenes in good yields
with excellent regioselectivity (entries 2, 4, 6, 8, 9, 11, and 13). The
observed effects of internal alkyne structures on regioselectivity are
clearly in agreement with the involvement of vinyl cations in this
process and suggest that the regioselectivity depends on the elec-
tronic effect. The selectivity would favor the vinyl cation in-
termediate, that is, most stabilized to effect electrophilic attack.
In striking contrast to the observation that the terminal alkynes
are generally more reactive than the internal alkynes in other
metal-catalyzed benzannulation of aryl acetaldehydes and ary-
lalkynes, only trace amount of the desired product could be
detected even with a prolonged heating at 60 ꢀC when the terminal
alkyne PhC^CH was subjected to the present annulation reaction
conditions. After several experiments, we were pleased to find that
replacement of terminal alkynes with silylated internal alkynes
could provide the desired mono- and di-substituted naphthalenes
in 56e78% isolated yields, companying with the elimination of
Me3SiOH (Table 3). The present reaction provides the first probe of
the chemoselectivity of annulation of aryl acetaldehydes and silyl
alkynes. It was found that the reactivity of silyl alkynes is controlled
by the electronic property of the substituents. Silyl acetylene with
electron-deficient aryl, such as p-chlorophenyl silyl acetylene,
reacted smoothly with various aryl-substituted acetaldehydes,
affording the corresponding substituted naphthalenes in satisfac-
tory yields with complete regioselectivity (Table 3, entries 2, 4, and
6). At the same time, electron-rich aryl, like p-methoxylphenyl,
seems to negatively affect the yields, but the regioselectivity
remained essentially constant (Table 3, entries 3 and 7). We then
went to the extent of attempting the reaction of 1a and 2g with
a catalytic amount (20 mol %) of FeCl3. To our delight, the reaction
ꢀ
amount in the presence of 0.2 equiv of YCl3 (entry 19), while 4 A
molecular sieves as a dehydrating reagent gave only a limited im-
provement possibly due to its moderate hydrophilicity, that is, not
enough to compete overwhelmingly against anhydrous FeCl3 under
the involved conditions (entries 20 vs 8). Taking into account the
price of anhydrous YCl3, however, the reactions were carried out
with FeCl3 alone thereafter.
As shown in Table 2, the reaction conditions described above are
effective for the transformation of a number of different substrate
combinations, several functional groups are tolerated. The in-
troduction of either the electron-donating or weak electron-
withdrawing (e.g., chloro) group at the para-position of the nu-
cleophilic benzene ring had only a slight influence on the reactivity
compared with those without a substituent on the aromatic ring

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X. Bu et al. / Tetrahedron 68 (2012) 7960e7965
Table 3
Table 4
Synthesis of substituted naphthalene derivatives via reaction of aldehydes with si-
Synthesis of substituted phenanthrene derivatives via reaction of aldehydes with
lylated alkynesa
substituted alkynesa
CHO
R
FeCl3
rt
R'
R
+
R'
1d
2a-h
3da-dh
Entry
1
2 (R4)
3
Yield (%)b
Entry
1
2
3
Yield (%)b
75
1
2
3
4
5
6
7
8
1a
1a
1a
1b
1c
1c
1c
1a
2f (p-CH3C6H4)
2g (p-ClC6H4)
2h (p-CH3OC6H4)
2g (p-ClC6H4)
2f (p-CH3C6H4)
2g (p-ClC6H4)
2h (p-CH3OC6H4)
2g (p-ClC6H4)
3af
66
78
56
71
70
78
61
58c
3ag
3ah
3bg
3cf
3cg
3ch
3ag
2a
a
2
3
2b
2c
58
69
Reaction conditions: Aldehyde (1.2 equiv), alkyne (1.0 equiv), FeCl3 (1.2 equiv),
1,2-DCE (3 mL), rt (18e26 ꢀC), 2 h.
b
Isolated yield.
FeCl3 (0.2 equiv).
c
worked with catalytic amount of FeCl3 as well, giving 3ag in 58%
yield (Table 3, entry 8). This finding further hints that the key to the
success of the iron-based catalytic cycle relies on the possibility of
preventing the Fe3þ ion from coordinating to the resulting water
through either the judicious avoidance of water formation or the
use of strong dehydrating reagents.
4
5
2d
2f
81
63
Phenanthrene ring is extensively presented in natural products,
pharmaceuticals, materials, and many other important organic
molecules.2 A number of methods for construction of phenan-
threne ring have been developed.12 Although quite efficient, these
reactions usually require the initial synthesis of complex starting
materials or the use of high cost of catalysts; an additional step that
sometimes involves expensive or toxic reagents and requires
chemical separations. Having demonstrated the feasibility of FeCl3-
promoted benzannulation reaction of aryl acetaldehydes with in-
ternal alkynes, we sought to determine whether annulation re-
action of naphthyl acetaldehydes and internal alkynes could also be
achieved. Thus, naphthyl acetaldehyde 1d was prepared and
treated with several different internal alkynes in the presence of
FeCl3 under the reaction conditions similar to those described
above (Table 4). As observed in the related transformations of
substrates bearing aryl nucleophiles, the corresponding substituted
phenanthrenes were also been synthesized in moderate to good
yields with excellent regioselectivity (Table 4, entries 1e4). In ad-
dition, the reaction works well for a variety of silylated alkynes to
give the desilylation products 1-arylphenanthrenes with complete
regioselectivity in moderate yields (Table 4, entries 5e7). The
structures of 3df (Fig. 1), 3dg (Fig. 2) and 3dh (Fig. 3) were further
confirmed by X-ray diffraction analysis.
6
2g
2h
62
55
7
a
Reaction conditions: Aldehyde (1.2 equiv), alkyne (1.0 equiv), FeCl3 (1.0 equiv),
1,2-DCE (3 mL), rt, 2 h.
b
Isolated yield.
Based on the above results, a plausible mechanism for the
formation of 3 is proposed in Scheme 1. Initially, the coordination
of the carbonyl oxygen to FeCl3 followed by electrophilic attack on
the aryl acetylene leads to the formation of a new CeC bond at the
b
carbon of the aryl acetylene as the resulting vinyl carbocation
is stabilized by the aryl group. Then, the intramolecular
FriedeleCrafts reaction of intermediate II effects closure of the
dihydronaphthalene ring, which undergo subsequently the tan-
dem H-transfer/H2O elimination in order to aromatize the rings to
form the product. In case of silylated alkynes, 1,5-hydrogen shift
should be involved along with the preferential elimination of
Me3SiOH or Me3SiOSiMe3. This difference between the elimina-
tion products of silylated alkynes and other alkynes might be
attributed to the stronger oxophilic character and larger steric
hindrance of trimethylsilyl compared with the hydrogen atom.
The observed influence of the resulting water on the loading
Fig. 1. ORTEP plot of the X-ray crystal structure of 3df.
amount of the catalyst and ligand effects provide further evidence
to support our mechanistic hypothesis and suggest that the
bonding strength of iron ion to aldehyde plays a key role in de-
termining the reaction, thereby the compatitive coordination of
H2O to Fe3þ hindering the progress of the catalytic cycle.

X. Bu et al. / Tetrahedron 68 (2012) 7960e7965
7963
3. Conclusions
In conclusion, we have developed a simple, highly regiose-
lective, and versatile protocol to synthesize substituted naphtha-
lene and phenanthrene derivatives via FeCl3 promoted annulation
of aryl and naphthyl acetaldehydes with a variety of internal al-
kynes. The experiments described herein suggest that the co-
ordination of the iron ion to aldehyde plays a key role in
determining the reaction, and is strongly influenced by both the
structure of the Fe catalyst and the competitive coordination of the
newly formed water. Significantly, the present catalytic system not
only differentiates between internal and terminal alkynes but also
shows unprecedented complete Me3SiOH elimination selectivity
for silyl alkyne substrates.
4. Experimental section
4.1. General methods
Fig. 2. ORTEP plot of the X-ray crystal structure of 3dg.
The solvents were dried using the standard technique. The re-
action was carried out under an argon atmosphere. 1H NMR spectra
and 13C NMR specta were recorded at a Bruker 400 MHz using
CDCl3 as solvent. High resolution mass spectra (HRMS) were
recorded on Bruker micrOTOF II using ESI ionization sources.
Melting points were performed on WRS-2 Melting Point Apparatus.
Infrared spectra were recorded on a FTIR spectrometer. The naph-
thalenes 3aa,9a 3ad,4b 3af,9b 3ag,9c 3ah,9d 3bg,9e 3cf,9e 1b,9f 1c,9f
1d,9g were identified by comparing their spectral data with those
reported in the literature.
4.2. General procedure for the synthesis of aldehydes
To a suspension of LiAlH4 in dry THF was added the corre-
sponding acid dissolved in dry THF dropwiselyat room temperature.
Then the mixture was stirred for 2 h and quenched with saturated
NH4Cl. The mixture was extracted with chloroform and dried over
anhydrous Na2SO4. Then the solvent was evaporated and the
product was used without further purification. The crude alcohol
was dissolved in dry DCM and DMP (DesseMartin Periodinane) was
added. The resulting mixture was stirred at room temperature for
2 h and quenched with Na2S2O3/NaHCO3 (v/v¼1/1). The aqueous
phase was extracted with DCM and dried over anhydrous Na2SO4.
The solvent was evaporated to afford the corresponding aldehydes.
Fig. 3. ORTEP plot of the X-ray crystal structure of 3dh.
4.3. General procedure for the synthesis of naphthalene and
phenanthrene derivatives
To a mixture of alkyne and aldehyde in 1,2-DCE was added an-
hydrous FeCl3. The solution was stirred at room temperature until
the alkyne disappeared detected by TLC. Then the solvent was
evaporated and the residue was subjected to chromatography di-
rectly eluting with petro ether to afford the corresponding product.
4.3.1. 1-(4-Methoxyphenyl)-2-phenylnaphthalene (3ab). Pale yel-
low crystal; mp 104.5e105.9 oC; IR (KBr) (cmꢁ1): 3055, 2947, 2927,
n
1607, 1509, 1489, 1458, 1437, 1380, 867, 837, 759, 698 cmꢁ1; 1H NMR
(CDCl3, 400 MHz)
d
7.94 (d, J¼8 Hz, 2H), 7.76 (d, J¼8 Hz, 1H), 7.61 (d,
J¼8.4 Hz, 1H), 7.53e7.49 (m, 1H), 7.46e7.42 (m, 1H), 7.25e7.13 (m,
7H), 6.90e6.86 (m, 2H), 3.83 (s, 3H); 13C NMR (CDCl3, 100 MHz)
d
158.48, 142.33, 138.64, 137.43, 133.16, 132.98, 132.60, 131.32,
130.27, 128.46, 128.01, 127.78, 127.54, 127.00, 126.28, 126.22, 125.77,
113.44, 55.28; HRMS (ESI) calcd for C23H19O (MþH) 311.1436, found
311.1421.
4.3.2. 1,2-Dip-tolylnaphthalene (3ac). Pale yellow crystal; mp
112.5e113.8 ꢀC; IR (KBr) (cmꢁ1): 3045, 3024, 2922, 2850, 1612,
n
Scheme 1. Possible mechanism for the formation of 3.

7964
X. Bu et al. / Tetrahedron 68 (2012) 7960e7965
1514, 1494, 1458, 1371, 857, 811, 749, 724, 682, 590, 585, 554, 539,
508, 431 cmꢁ1; 1H NMR (CDCl3, 400 MHz)
127.67, 127.53, 127.45, 126.74, 126.22, 125.80, 22.17; HRMS (ESI)
calcd for C23H19 (MþH) 295.1487, found 295.1471.
d
7.93 (d, J¼8.4 Hz, 2H),
7.72 (d, J¼8.4 Hz, 1H), 7.61 (d, J¼8.4 Hz, 1H), 7.52e7.49 (m, 1H),
7.44e7.40 (m, 1H), 7.18e7.10 (m, 6H), 7.04 (d, J¼8.4 Hz, 2H), 2.41 (s,
4.3.9. 1-(4-Methoxyphenyl)-7-methyl-2-phenylnaphthalene (3cb).
3H), 2.33 (s, 3H); 13C NMR (CDCl3,100 MHz)
d
139.34,138.33,137.63,
Yellow solid; mp 99.8e101.7 ꢀC; IR (KBr) (cmꢁ1): 3045, 2999, 2922,
n
136.25, 136.20, 135.77, 133.06, 132.83, 131.39, 130.11, 128.71, 128.64,
128.51, 127.95, 127.50, 127.01, 126.19, 125.63, 21.42, 21.26; HRMS
(ESI) calcd for C24H21 (MþH) 309.1643, found 309.1639.
1608, 1511, 1493, 1454, 1289, 1244, 1177, 1030, 840, 824, 762, 752,
702 cmꢁ1; 1H NMR (CDCl3, 400 MHz)
d
7.89 (d, J¼8.8 Hz,1H), 7.85 (d,
J¼8.4 Hz, 1H), 7.55e7.52 (dd, J¼2.8 and 8.8 Hz, 2H), 7.37e7.35 (dd,
J¼2.0 and 8.4 Hz, 1H), 7.24e7.13 (m, 7H), 6.91e6.87 (m, 2H), 3.85 (s,
3H), 2.45 (s, 3H); 13C NMR (CDCl3,100 MHz)
d 158.35,142.49,138.72,
4.3.3. 7-Chloro-1,2-diphenylnaphthalene (3ba). Yellow crystal; mp
149.9e151.8 ꢀC; IR (KBr) (cmꢁ1): 3060, 3024, 1614, 1597, 1586,
n
136.74, 135.96, 133.24, 132.62, 131.46, 131.21, 130.25, 128.00, 127.88,
127.71,127.57,127.27,126.12,125.85,113.38, 55.25, 22.17; HRMS (ESI)
calcd for C24H21O (MþH) 325.1592, found 325.1583.
1487, 1446, 1361, 1258, 1081, 1028, 967, 841, 765, 701 cmꢁ1; 1H NMR
(CDCl3, 400 MHz)
d
7.91 (d, J¼8.4 Hz, 1H), 7.86 (d, J¼8.8 Hz,1H), 7.70
(s, 1H), 7.60 (d, J¼8.4 Hz, 1H), 7.47e7.44 (dd, J¼2.4 and 8.8 Hz, 1H),
7.36e7.31 (m, 3H), 7.25e7.15 (m, 7H); 13C NMR (CDCl3, 100 MHz)
4.3.10. 7-Methyl-1,2-dip-tolylnaphthalene (3cc). Pale yellow crys-
tal; mp 115.4e116.6 ꢀC; IR (KBr) (cmꢁ1): 3040, 3024, 2963, 2937,
n
d
141.68, 139.53, 138.36, 137.10, 133.59, 132.36, 131.43, 131.13, 130.13,
2916, 2850, 1622, 1494, 1432, 1376, 842, 826, 790, 729 cmꢁ1
NMR (CDCl3, 400 MHz)
;
1H
129.61, 128.72, 128.15, 127.79, 127.52, 127.16, 126.72, 126.54, 125.77;
HRMS (ESI) calcd for C22H15Cl (MþH) 314.0862, found 315.0917.
d
7.89 (d, J¼8.8 Hz, 1H), 7.84 (d, J¼8.4 Hz,
1H), 7.53 (d, J¼8.0 Hz, 1H), 7.50 (s, 1H), 7.35 (d, J¼8.4 Hz, 1H),
7.18e7.09 (m, 6H),7.03 (d, J¼8.0 Hz, 2H), 2.44 (s, 3H), 2.42 (s, 3H),
4.3.4. 7-Chloro-1-(4-methoxyphenyl)-2-phenylnaphthalene (3bb).
Yellow solid; mp 118.6e119.2 ꢀC; IR (KBr) (cmꢁ1): 3060, 3024,
n
2.33 (s, 3H); 13C NMR (CDCl3, 100 MHz)
d 139.50, 138.43, 136.97,
2927, 1607, 1504, 1489, 1458, 1443, 1242, 1027, 878, 826, 754,
136.31, 136.11, 135.86, 135.64, 133.15, 131.41, 131.09, 130.10, 128.69,
128.45, 127.89, 127.83, 127.76, 127.24, 125.85, 22.15, 21.43, 21.24;
HRMS (ESI) calcd for C25H23 (MþH) 323.1800, found 323.1786.
698 cmꢁ1; 1H NMR (CDCl3, 400 MHz)
d
7.71 (s,1H), 7.58 (d, J¼8.4 Hz,
1H), 7.45e7.43 (dd, J¼2.0 and 8.4 Hz, 1H), 7.24e7.15 (m, 5H), 7.09 (d,
J¼8.8 Hz, 2H), 6.87 (d, J¼8.8 Hz, 2H), 3.84 (s, 3H); 13C NMR (CDCl3,
100 MHz)
d 158.60, 141.84, 139.64, 136.76, 133.92, 132.44, 132.23,
4.3.11. 2-Ethyl-7-methyl-1-phenylnaphthalene (3cd). Pale yellow
131.15, 130.48, 130.09, 129.55, 128.70, 127.79, 127.27, 126.60, 126.40,
125.79, 113.60, 55.25; HRMS (ESI) calcd for C23H17ClONa (MþNa)
367.0866, found 367.0861.
oil; IR (KBr)
2509, 1489, 1437, 1371, 837, 770, 744, 698 cmꢁ1
400 MHz)
n
(cmꢁ1): 3045, 3014, 2963, 2922, 2870, 1622, 1597,
;
1H NMR (CDCl3,
d
7.83 (d, J¼8.0 Hz, 1H), 7.78 (d, J¼8.4 Hz, 1H), 7.56e7.46
(m, 3H), 7.43 (d, J¼8.4 Hz, 1H), 7.35e7.28 (m, 3H), 7.17 (s, 1H), 2.57
4.3.5. 7-Chloro-1,2-dip-tolylnaphthalene (3bc). Pale yellow crystal;
(q, J¼7.6 Hz, 2H), 2.40 (s, 3H), 1.16 (t, J¼7.6 Hz, 3H); 13C NMR (CDCl3,
mp 138.8e140.0 oC; IR (KBr) (cmꢁ1): 3022, 2923, 2850, 1611, 1511,
n
100 MHz)
d 139.81, 139.53, 137.03, 135.50, 133.30, 130.46, 130.24,
1493, 1433, 1384, 1362, 1112, 1080, 881, 842, 818, 791, 587,
520 cmꢁ1 1H NMR (CDCl3, 400 MHz)
;
d
7.87 (d, J¼8.4 Hz, 1H), 7.83
128.33, 127.70, 127.45, 127.18, 127.03, 126.38, 125.47, 27.16, 22.08,
16.18; HRMS (ESI) calcd for C19H19 (MþH) 247.1487, found 247.1490.
(d, J¼8.8 Hz, 1H), 7.68 (s, 1H), 7.57 (d, J¼8.8 Hz, 1H), 7.44e7.41 (dd,
J¼2.0 and 8.4 Hz, 1H), 7.15 (d, J¼8.0 Hz, 2H), 7.09e7.01 (m, 6H), 2.39
(s, 3H), 2.31 (s, 3H); 13C NMR (CDCl3, 100 MHz)
d 139.41, 138.88,
4.3.12. 1-(4-Chlorophenyl)-7-methylnaphthalene
solid; mp 120.5e122.3 ꢀC; IR (KBr) (cmꢁ1): 3050, 2916, 2845, 1622,
1597, 1489, 1427, 1093, 1016, 816, 749 cmꢁ1 1H NMR (CDCl3,
(3cg). Yellow
n
137.00, 136.61, 136.05, 135.42, 133.87, 132.18, 131.25, 131.06, 130.01,
129.55, 128.93, 128.58, 127.30, 126.53, 125.83, 21.44, 21.25; HRMS
(ESI) calcd for C24H20Cl (MþH) 343.1254, found 343.1230.
;
400 MHz)
d
7.85 (d, J¼4.4 Hz, 1H), 7.83 (d, J¼5.2 Hz, 1H), 7.63 (s, 1H),
7.51e7.43 (m, 5H), 7.37 (dd, J¼1.2 and 7.2 Hz, 2H), 2.48 (s, 3H); 13C
4.3.6. 7-Chloro-2-ethyl-1-phenylnaphthalene (3bd). White oil; IR
NMR (CDCl3, 100 MHz)
d 139.49, 138.35, 136.12, 133.29, 131.47,
(KBr)
1083, 965, 888, 837, 765, 724, 708 cmꢁ1; 1H NMR (CDCl3, 400 MHz)
7.83e7.78 (m, 2H), 7.56e7.47 (m, 4H), 7.39e7.37 (m, 2H),
n
(cmꢁ1): 3055, 2963, 2927, 2870, 1612, 1586, 1499, 1458, 1360,
128.58, 128.33, 128.28, 127.86, 127.16, 124.63, 124.58, 22.12; HRMS
(ESI) calcd for C17H14Cl (MþH) 253.0784, found 253.0757.
d
7.31e7.28 (m, 2H), 2.60e2.54 (q, J¼7.2 Hz, 2H), 1.71e1.13 (t,
4.3.13. 1-(4-Methoxyphenyl)-7-methylnaphthalene
oil; IR(KBr)
(cmꢁ1): 3040, 2999, 2932, 2855, 2829, 1607, 1509,
1458, 1437, 1371, 1278, 1247, 1170, 1032, 821, 790, 759, 569,
518 cmꢁ1 1H NMR (CDCl3, 400 MHz)
(3ch). Yellow
J¼7.2 Hz, 3H); 13C NMR (CDCl3, 100 MHz)
d 140.74, 138.81, 137.06,
n
133.98, 131.82, 130.31, 130.24, 129.42, 128.57, 127.59, 127.54, 127.43,
125.86, 125.41, 27.19, 16.05; HRMS (ESI) calcd for C18H16Cl (MþH)
267.0941, found 267.0930.
;
d
7.82 (dd, J¼4.0 and 8.4 Hz,
2H), 7.71 (s, 1H), 7.48e7.44 (m, 3H), 7.40e7.34 (m, 2H), 7.07 (dd,
J¼2.4 and 6.8 Hz, 2H), 3.92 (s, 3H), 2.47 (s, 3H); 13C NMR (CDCl3,
4.3.7. 7-Chloro-2-methyl-1-phenylnaphthalene (3be). Colorless oil;
100 MHz)
d 158.99, 139.35, 135.75, 133.48, 132.21, 132.10, 131.23,
IR (KBr)
n
(cmꢁ1): 3055, 3019, 2922, 2855, 1617, 1597, 1494, 1442,
128.25, 128.08, 127.23, 127.17, 125.05, 124.63, 113.83, 55.46, 22.11;
HRMS (ESI) calcd for C18H17O (MþH) 249.1279, found 249.1287.
1360, 1129, 1078, 831, 775, 734, 703, 616 cmꢁ1
;
1H NMR (CDCl3,
400 MHz)
d 7.79e7.75 (m, 2H), 7.55e7.42 (m, 5H), 7.38e7.35 (dd,
J¼2.0 and 8.4 Hz, 1H), 7.28e7.26 (m, 2H), 2.25 (s, 3H); 13C NMR
4.3.14. 1,2-Diphenylphenanthrene (3da). Yellow crystal; mp
143.8e144.7 ꢀC; IR (KBr) (cmꢁ1): 3055, 3023, 2924, 1598, 1493,
n
(CDCl3, 100 MHz)
d 139.11, 137.67, 134.57, 133.81, 131.88, 130.31,
130.15, 129.48, 129.03, 128.73, 127.46, 127.15, 125.79, 125.13, 21.03;
HRMS (ESI) calcd for C17H14Cl (MþH) 253.0784, found 253.0778.
1483, 1456, 1443, 1433, 1257, 1025, 828, 795, 759, 750, 701, 684,
584 cmꢁ1 1H NMR (CDCl3, 400 MHz)
; d 8.82 (t, 2H), 7.92 (d,
J¼8.0 Hz, 1H), 7.80e7.66 (m, 5H), 7.40e7.22 (m, 10H); 13C NMR
4.3.8. 7-Methyl-1,2-diphenylnaphthalene (3ca). Yellow crystal; mp
(CDCl3, 100 MHz)
d 141.97, 139.47, 139.41, 138.65, 131.70, 131.65,
121.8e122.7 ꢀC; IR (KBr) (cmꢁ1): 3045, 3019, 2963, 2911, 2845,
n
130.97, 130.27, 130.20, 129.72, 128.64, 128.54, 127.96, 127.73, 127.14,
126.88, 126.83, 126.81, 126.37, 125.38, 123.00, 122.28; HRMS (ESI)
calcd for C26H19 (MþH) 331.1487, found 331.1481.
1627, 1597, 1489, 1437, 1365, 842, 775, 759, 739, 698 cmꢁ1; 1H NMR
(CDCl3, 400 MHz)
7.93 (d, J¼8.8 Hz, 1H), 7.87 (d, J¼8 Hz, 1H), 7.56
(d, J¼8.4 Hz, 1H), 7.50 (s, 1H), 7.39e7.30 (m, 4H), 7.26e7.21 (m, 7H),
2.45 (s, 3H); 13C NMR (CDCl3, 100 MHz)
142.31, 139.29, 138.57,
137.10, 136.07, 132.89, 131.61, 131.17, 130.24, 128.07, 127.91, 127.89,
d
d
4.3.15. 1-(4-Methoxyphenyl)-2-phenylphenanthrene (3db). Yellow
solid; mp 177.6e178.9 ꢀC; IR (KBr) (cmꢁ1): 3050, 3004, 2957, 2922,
n

X. Bu et al. / Tetrahedron 68 (2012) 7960e7965
7965
2850, 1612, 1514, 1458, 1247, 1178, 1029, 821, 761, 750, 701 cmꢁ1; 1H
NMR (CDCl3, 400 MHz)
Supplementary data
d
8.80 (d, J¼3.6 Hz, 1H), 8.78 (d, J¼3.2 Hz,
1H), 7.91 (dd, J¼1.6 and 8.0 Hz, 1H), 7.78e7.62 (m, 5H), 7.28e7.22
(m, 5H), 7.18e7.15 (m, 2H), 6.90 (dd, J¼2.0 and 7.2 Hz, 2H), 3.84 (s,
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.tet.2012.07.007.
3H); 13C NMR (CDCl3, 100 MHz)
d 158.44, 142.13, 139.65, 138.30,
132.65, 131.68, 131.53, 131.29, 130.28, 130.19, 129.74, 128.66, 128.51,
127.78, 127.03, 126.76, 126.27, 125.44, 122.99, 122.10, 113.40, 55.25;
HRMS (ESI) calcd for C27H21O (MþH) 361.1592, found 361.1574.
References and notes
1. For selected papers: (a) Silva, O.; Gomes, E. T. J. Nat. Prod. 2003, 66, 447e449; (b)
Dai, J.; Liu, Y.; Zhou, Y.-D.; Nagle, D. G. J. Nat. Prod. 2007, 70, 1824e1826; (c)
4.3.16. 1,2-Dip-tolylphenanthrene
147.6e148.7 ꢀC; IR (KBr) (cmꢁ1): 3046, 3016, 2918, 2854, 1513,
1490,1455, 840, 812, 775, 746, 587 cmꢁ1; 1H NMR (CDCl3, 400 MHz)
8.80 (d, J¼8.8 Hz, 2H), 7.90 (d, J¼7.6 Hz, 1H), 7.78e7.64 (m, 5H),
7.18e7.13 (m, 6H), 7.07 (d, J¼7.6 Hz, 2H), 2.43 (s, 3H), 2.35 (s, 3H);
13C NMR (CDCl3, 100 MHz)
139.39, 139.15, 138.57, 136.47, 136.29,
(3dc). Yellow
solid;
mp
€
Brasholz, M.; Sorgel, S.; Azap, C.; Reißig, H.-U. Eur. J. Org. Chem. 2007,
3801e3814; (d) Krohn, K.; Kounam, S. F.; Cludius-Brandt, S.; Draeger, S.; Schulz,
B. Eur. J. Org. Chem. 2008, 3615e3618; (e) Lowell, A. N.; Fennie, M. W.; Ko-
zlowski, M. C. J. Org. Chem. 2008, 73, 1911e1918; (f) Li, Z. G.; Jin, Z.; Huang, R. Q.
Synthesis 2001, 2365e2378 and references therein.
2. For reviews: (a) de Koning, C. B.; Rousseau, A.; van Otterlo, W. A. L. Tetrahedron
2003, 59, 7e36; (b) Katritzky, A. R.; Li, J.; Xie, L. Tetrahedron 1999, 55,
8263e8293.
3. (a) Viswanathan, G. S.; Wang., M. W.; Li., C. J. Angew. Chem., Int. Ed. 2002, 41,
2138e2139; (b) Kabalka, G. W.; Ju., Y. H.; Wu., Z. Z. J. Org. Chem. 2003, 68,
7915e7917; (c) Balamurugan, R.; Gudla, V. Org. Lett. 2009, 11, 3116e3119.
4. For reviews, see: (a) Sherry, B. D.; Furstner., A. Acc. Chem. Res. 2008, 41,
1500e1511; (b) Bolm, C.; Legros., J.; Paih., J. L.; Zani., L. Chem. Rev. 2004, 104,
6217e6254; (c) Enthaler, S.; Junge, K.; Beller, M. Angew. Chem., Int. Ed. 2008, 47,
3317e3321; (d) Correa, A.; Mancheno, O. G.; Bolm, C. Chem. Soc. Rev. 2008, 37,
1108e1117; (e) Gaillard, S.; Renaud, J. L. ChemSusChem 2008, 1, 505e509; (f)
n
d
d
135.82, 131.66, 131.46, 131.20, 130.31, 130.06, 129.56, 128.83, 128.73,
128.52, 128.50, 126.93, 126.73, 126.68, 125.51, 122.98, 122.09, 21.42,
21.25; HRMS (ESI) calcd for C28H23 (MþH) 359.1800, found
359.1772.
€
~
4.3.17. 2-Ethyl-1-phenylphenanthrene (3dd). Off-white crystal; mp
84.4e85.6 ꢀC; IR (KBr) (cmꢁ1): 3044, 2960, 2926, 2866, 1598, 1492,
n
ꢁ
Czaplik, W. M.; Mayer., M.; Cvengros., J.; Wangelin., A. J. ChemSusChem 2009, 2,
1458, 1439, 1368, 821, 753, 726, 703 cmꢁ1
400 MHz)
8.74 (t, J¼8.8 Hz, 2H), 7.87 (d, J¼8.0 Hz, 1H), 7.71e7.75
(m, 7H), 7.39e7.35 (m, 3H), 2.63 (q, J¼8.0 Hz, 2H), 1.20 (t, J¼8.0 Hz,
3H); 13C NMR (CDCl3, 100 MHz)
140.54, 139.93, 138.91, 131.40,
;
1H NMR (CDCl3,
396e417.
ꢂ
ꢂ
5. Vass, A.; Dudas, J.; Toth, J.; Varma, R. S. Tetrahedron Lett. 2001, 42, 5347e5349.
6. (a) Yang, L.; Lei, C. H.; Wang, D. X.; Huang, Z. T.; Wang, M. X. Org. Lett. 2010, 12,
3918e3921; (b) Li, H. F.; Yang., J. Y.; Liu., Y. H.; Li., Y. Z. J. Org. Chem. 2009, 74,
6797e6801; (c) Watahiki, T.; Akabane, Y.; Mori, S.; Oriyama, T. Org. Lett. 2003, 5,
3045e3048; (d) Zou, T.; Pi, S. S.; Li, J. H. Org. Lett. 2009, 11, 453e456; (e) Li, Z. X.;
Duan., Z.; Kang., J. X.; Wang., H. Q.; Yu., L. J.; Wu., Y. J. Tetrahedron 2008, 64,
1924e1930.
d
d
131.20, 130.47, 130.37, 128.51, 128.49, 128.41, 127.37, 127.18, 126.68,
126.39, 125.34, 122.79, 122.31, 27.11, 16.01; HRMS (ESI) calcd for
C22H19 (MþH) 283.1487, found 283.1474.
7. (a) Thirupathi, P.; Kim, S. S. J. Org. Chem. 2010, 75, 5240e5249; (b) Wang, Z. Y.;
Sun., X. Y.; Wu., J. Tetrahedron 2008, 64, 5013e5018.
8. (a) Xu, X. B.; Liu., J.; Liang., L. F.; Li., H. F.; Li., Y. Z. Adv. Synth. Catal. 2009, 351,
4.3.18. 1-p-Tolylphenanthrene
83.5e84.3 ꢀC; IR (KBr) (cmꢁ1): 3045, 3019, 2916, 1586, 1504, 1489,
1458, 1412, 1381, 867, 831, 801, 754, 724, cmꢁ1 1H NMR (CDCl3,
400 MHz)
8.77 (t, J¼8.4 Hz, 2H), 7.90 (t, J¼8.4 Hz, 2H), 7.73e7.57
(m, 5H), 7.45 (d, J¼8.0 Hz, 2H), 7.36 (d, J¼8.0 Hz, 2H), 2.51 (s, 3H);
13C NMR (CDCl3, 100 MHz)
141.09, 138.25, 137.04, 131.83, 130.78,
130.54, 130.22, 130.11, 129.12, 128.55, 128.03, 126.87, 126.77, 126.72,
126.09, 124.83, 123.08, 122.08, 21.39; HRMS (ESI) calcd for C21H16Na
(MþNa) 291.1150, found 291.1126.
(3df). White
crystal;
mp
2599e2604; (b) Li, R. S.; Wang., S. R.; Lu., W. J. Org. Lett. 2007, 9, 2219e2222; (c)
n
ꢂ
Cantagrel, G.; de Carne-Carnavalet, B.; Meyer, C.; Cossy, J. Org. Lett. 2009, 11,
;
4262e4265; (d) Hashimoto, T.; Izumi, T.; Kutubi, M. S.; Kitamura, T. Tetrahedron
Lett. 2010, 51, 761e763; (e) Bu, X. L.; Zhang., Z. X.; Zhou., X. G. Organometallics
2010, 29, 3530e3534.
9. (a) Liang, Z. D.; Hou., W. Z.; Du., Y. F.; Zhang., Y. L.; Pan., Y.; Mao., D.; Zhao., K.
Org. Lett. 2009, 11, 4978e4981; (b) Bonnamour, J.; Bolm, C. Org. Lett. 2008, 10,
2665e2667; (c) Kumaraswamy, G.; Murthy, A. N.; Pitchaiah, A. J. Org. Chem.
2010, 75, 3916e3919; (d) Pan, S. G.; Liu., J. H.; Li., H. R.; Wang., Z. Y.; Guo., X. W.;
Li., Z. P. Org. Lett. 2010, 12, 1932e1935.
d
d
10. For selected papers: (a) Iovel, I.; Mertins, K.; Kischel, J.; Zapf, A.; Beller, M.
Angew. Chem., Int. Ed. 2005, 44, 3913e3917; (b) Huang, W.; Shen, Q. S.;
Wang, J. L.; Zhou, X. G. J. Org. Chem. 2008, 73, 1586e1589; (c) Huang, W.;
Zheng, P. Z.; Zhang, Z. X.; Liu, R. T.; Chen, Z. X.; Zhou, X. G. J. Org. Chem.
2008, 73, 6845e6848; (d) Wang, J. L.; Huang., W.; Zhang., Z. X.; Xiang., X.;
4.3.19. 1-(4-Chlorophenyl)phenanthrene (3dg). White solid; mp
95.7e98.7 ꢀC; IR (KBr) (cmꢁ1): 3070, 3060, 3045, 3019, 2916, 1597,
n
ꢂ
Liu., R. T.; Zhou., X. G. J. Org. Chem. 2009, 74, 3299e3304; (e) Guerinot, A.;
1504, 1489, 1448, 1381, 1104, 1016, 1001, 872, 837, 801, 744, 713,
482 cmꢁ1; 1H NMR (CDCl3, 400 MHz)
d
8.77 (d, J¼8.8 Hz, 2H), 7.90
Serra-Muns, A.; Gnamm, C.; Bensoussan, C.; Reymond, S.; Cossy, J. Org. Lett.
2010, 12, 1808e1811; (f) Fan, J. M.; Wan., C. F.; Sun., G. J.; Wang., Z. Y. J. Org.
Chem. 2008, 73, 8608e8611; (g) Xu, T. Y.; Yang., Q.; Li., D. P.; Dong., J. H.; Yu.,
Z. K.; Li., Y. X. Chem.dEur. J. 2010, 16, 9264e9272; (h) Li, B. J.; Xu., L.; Wu.,
Z. H.; Guan., B. T.; Sun., C. L.; Wang., B. Q.; Shi., Z. J. J. Am. Chem. Soc. 2009,
131, 14656e14657; (i) Zhan, Z. P.; Yu., J. L.; Liu., H. J.; Cui., Y. Y.; Yang., R. F.;
Yang., W. Z.; Li., J. P. J. Org. Chem. 2006, 71, 8298e8301; (j) Womack, G. B.;
Angeles., J. G.; Fanelli., V. E.; Indradas., B.; Snowden., R. L.; Sonnay., P. J. Org.
Chem. 2009, 74, 5738e5741; (k) Maeda, S.; Horikawa, N.; Obora, Y.; Ishii, Y. J.
Org. Chem. 2009, 74, 9558e9561; (l) Li, H. H.; Jin., Y. H.; Wang., J. Q.; Tian.,
S. K. Org. Biomol. Chem. 2009, 7, 3219e3221; (m) Xu, T. Y.; Yu., Z. K.; Wang.,
L. D. Org. Lett. 2009, 11, 2113e3116; (n) Xu, X. B.; Xu., X. L.; Li, H. F.; Xie., X.;
Li., Y. Z. Org. Lett. 2010, 12, 100e103; (o) Bu, X. L.; Hong, J. Q.; Zhou, X. G.
Adv. Synth. Catal. 2011, 353, 2111e2118.
(dd, J¼1.2 and 8.0 Hz,1H), 7.78e7.62 (m, 5H), 7.54e7.44 (m, 5H); 13C
NMR (CDCl3, 100 MHz)
d 139.59, 133.47, 131.61, 130.83, 130.43,
129.85,128.62, 127.94, 127.26,126.94,126.90, 126.08, 124.27, 123.06,
122.59; HRMS (ESI) calcd for C20H14Cl (MþH) 289.0784, found
289.0777.
4.3.20. 1-(4-Methoxyphenyl)phenanthrene (3dh). Yellow crystal; 1H
NMR (CDCl3, 400 MHz)
d
8.74 (q, J¼8.8 Hz, 2H), 7.87 (q, J¼8.8 Hz,
2H), 7.71e7.60 (m, 4H), 7.55 (d, J¼7.2 Hz, 1H), 7.45 (d, J¼8.8 Hz, 2H),
7.06 (d, J¼8.4 Hz, 2H), 3.91 (s, 3H); 13C NMR (CDCl3, 100 MHz)
11. For selected papers: (a) Correa, A.; Elmore, S.; Bolm, C. Chem.dEur. J. 2008, 14,
3527e3529; (b) Hatakeyama, T.; Nakagawa, N.; Nakamura, M. Org. Lett. 2009, 11,
4496e4499; (c) Correa, A.; Bolm, C. Adv. Synth. Catal. 2008, 350, 391e394; (d)
Xie, X.; Xu, X. B.; Li, H. F.; Xu, X. L.; Yang, J. Y.; Li, Y. Z. Adv. Synth. Catal. 2009, 351,
1263e1267; (e) Li, Z.; Hong, J. Q.; Weng, L. H.; Zhou, X. G. Tetrahedron 2011, 68,
1552e1559.
d
159.03, 140.74, 133.52, 131.80, 131.38, 130.78, 130.51, 130.18,
128.55, 128.07, 126.85, 126.77, 126.73, 126.09, 124.78, 123.07, 121.97,
113.83, 55.48; HRMS (ESI) calcd for C21H17O (MþH) 285.1279, found
285.1289.
12. For selected papers: (a) Yao, T. L.; Campo., M. A.; Larock., R. C. J. Org. Chem. 2005,
70, 3511e3517; (b) Kim, Y. H.; Lee., H.; Kim., Y. J.; Kim., B. T.; Heo., J. N. J. Org.
Chem. 2008, 73, 495e501; (c) Liu, Y. L.; Liang., Y.; Pi., S. F.; Huang., X. C.; Li., J. H.
J. Org. Chem. 2009, 74, 3199e3202; (d) Catellani, M.; Motti, E.; Baratta, S. Org.
Lett. 2001, 3, 3611e3614; (e) Kanno, K. I.; Liu., Y. H.; Iesato., A.; Nakajima., K.;
Takahashi., T. Org. Lett. 2005, 7, 5453e5456; (f) Jana, R.; Biswas, A.; Samanta, S.;
Ray, J. K. Synthesis 2010, 2092e2100; (g) Yoshikawa, E.; Yamamoto, Y. Angew.
Chem., Int. Ed. 2000, 39, 173e175; (h) Radhakrishnan, K. V.; Yoshikawa., E.;
Yamamoto., Y. Tetrahedron Lett. 1999, 40, 7533e7535.
Acknowledgements
We thank the NNSF of China, 973 program (2009CB825300), the
Research Fund for the Doctoral Program of Higher Education of
China, and Shanghai Leading Academic Discipline Project for fi-
nancial support (B108).