Synthesis and Acid-Catalyzed Cyclization of 2-Alkenylstilbenes: A New Approach to the Substituted Indenes

Article abstract of DOI:10.1002/cjoc.201500587

A base-catalyzed ring-opening of 1-benzylisochromans 1 firstly produced 2-alkenylstilbenes 2, which then underwent a mild acid-catalyzed intramolecular cyclization to furnish 1,2-disubstituted indenes 3 in high yields. Subsequently, a base-catalyzed isomerization of the 1,2-disubstituted indenes 3 afforded the more stable 2,3-disubstituted indenes 4 in almost quantitative yields.

Full text of DOI:10.1002/cjoc.201500587

FULL PAPER
DOI: 10.1002/cjoc.201500587
Synthesis and Acid-Catalyzed Cyclization of 2-Alkenylstilbenes:
a New Approach to the Substituted Indenes
Wei Ding, Xiaoxin Shi,* and Xia Lu
Department of Pharmaceutical Engineering, School of Pharmacy, East China University of Science and Technology,
Shanghai 200237, China
A base-catalyzed ring-opening of 1-benzylisochromans 1 firstly produced 2-alkenylstilbenes 2, which then un-
derwent a mild acid-catalyzed intramolecular cyclization to furnish 1,2-disubstituted indenes 3 in high yields. Sub-
sequently, a base-catalyzed isomerization of the 1,2-disubstituted indenes 3 afforded the more stable 2,3-disub-
stituted indenes 4 in almost quantitative yields.
Keywords isochroman, stilbene, indene, cyclization, ring-opening, synthetic methodology
Introduction
on the above synthetic route.
Indene is a privileged structural motif in natural pro-
ducts,[1] pharmaceuticals[2] and functional materials.[3]
Indenes can also be used as ligands for many organo-
metallic complexes.[4] Consequently, indenes are a kind
of extremely important compounds, and have attracted
much attention of synthetic chemists. Up to now, vari-
ous synthetic methods for the formation of indenes have
been reported. These known methods include the dehy-
dration of indanols,[5] the cyclodehydration of aryl allyl-
lic alcohols,[6] the ring expansion of vinylcyclopro-
penes,[7] the cycloaddition of alkenylcyclopropanes with
aldehydes, imines and acetals,[8] the intramolecular
Friedel-Crafts cyclization of aryl 1,3-butadienes[9] and
cinnamaldehydes,[10] the transition metal-catalyzed cy-
cloaddition of various aryl compounds with alkynes[11]
and alkenes,[12] and some other miscellaneous meth-
ods.[13] However, considering the enormous importance
of indenes and their derivatives, development of more
efficient, practical, benign and low-cost new methods
for the synthesis of substituted indenes remains to be
highly desirable.
We have investigated a new synthetic route (Scheme
1) toward indenes starting from 1-benzyl-isochromans 1,
which can be readily prepared via oxa-Pictet-Spengler
reaction.[14] As can be seen in Scheme 1, a base-cata-
lyzed ring-opening of 1-benzyl-isochromans 1 firstly
produced 2-alkenyl-stilbenes 2; an acid-catalyzed in-
tramolecular cyclization of 2-alkenyl-stilbenes 2 then
furnished 1,2-disubstituted indenes 3; a base-catalyzed
isomerization of the 1,2-disubstituted indenes 3 finally
afforded the more stable 2,3-disubstituted indenes 4.
Herein, we want to report the details of the investigation
Scheme 1 The new synthetic route of indenes from 1-benzyl-
isochromans
R2
R1
R4
R3
R2
R1
R3
O
Base
elimination
Acid
cyclization
R4
2
1
R3
R3
R2
R1
R2
R1
Base
isomerization
R4
R4
4
3
Results and Discussion
At first, we tried the base-catalyzed ring-opening of
1-benzyl-6,7-dimethoxyisochroman 1a under various
conditions, the results are summarized in Table 1. As
can be seen from the Table 1, when compound 1a was
treated with a strong base in dimethylsulfoxide (DMSO),
(E)-4,5-dimethoxy-2-vinylstilbene 2a could be obtained
(Table 1, Entries 1－8), and the reaction of compound
1a with 3 equivalent of potassium hydroxide in DMSO
at 120 ℃ for 1 h furnished the product 2a in the best
yield (Entry 1). When compound 1a was treated with a
weak base in DMSO at 120 ℃, no reaction took place
at all (Entries 9－12). Notably, DMSO is very crucial
for the reaction, because when the reaction was per-
formed in other solvents such as ethanol, isopropanol,
propanol, butanol, ethylene glycol, 1,4-dioxane, 1,2-di-
*
E-mail: xxshi@ecust.edu.cn; Tel.: 0086-021-64252052; Fax: 0086-021-64252052
Received August 13, 2015; accepted September 27, 2015; published online November 13, 2015.
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cjoc.201500587 or from the author.
1276
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Chin. J. Chem. 2015, 33, 1276—1286

Synthesis and Acid-Catalyzed Cyclization of 2-Alkenylstilbenes
methoxyethane (DME) and N,N-dimethylformamide
(DMF), no reaction happened, and almost none of
product 2a could be detected (Entries 13－20).
chromans 1 to 2-alkenylstilbenes 2 was proposed in
Scheme 3. A strong base (KOH or NaH) would first re-
act with isochromans 1 to form the intermediate anions
I-1. Anions I-1 would then rapidly undergo ring-
opening via β-elimination to give the intermediate
compounds I-2. Next, when the reaction was performed
under condition A, the compounds I-2 would react with
KOH via path a to form the anions I-3, which would
finally undergo β-elimination to afford compounds 2.
When the reaction was performed under condition B,
the compounds I-2 reacted with ethyl acetate via path b
to give acetates I-4. Esters I-4 would then react with
NaH to form the anions I-5, which then underwent
β-elimination to afford compounds 2. Isolation of some
intermediates might support the above mechanism.
When the treatment of isochroman 2b with 3 equivalent
of KOH in DMSO at 120 ℃ (condition A) was
quenched at a mid-point, an intermediate compound 6
(Scheme 2) and product 2b were isolated. Also, when
the treatment of isochroman 1i with 4 equivalent of
NaH in DMSO/EtOAc (5∶1, V∶V) at 80 ℃ (condi-
tion B) was stopped at a mid-point, an intermediate
compound 7 (Scheme 2) and product 2i were isolated.
With the 2-alkenylstilbenes 2a－2n in hand, we next
attempted the acid-catalyzed cyclization of these com-
pounds. We first tried the acid-catalyzed cyclization of
(E)-4,5-dimethoxy-2-vinylstilbene 2a under various
conditions, the results are summarized in Table 3. As
can be seen from Table 3, when the reaction was per-
formed in chloroform or dichloromethane at reflux for 1
h by using 0.1 equivalent of p-toluenesulfonic acid
(PTSA) as the catalyst, 5,6-dimethoxy-1-methyl-2-
phenyl-1H-indene 3a was obtained in good yields (Ta-
ble 3, Entries 1 and 2). Other five solvents have been
examined, but the cyclization was sluggish in theses
solvents (Entries 5－9). Various Bronsted acids and
Lewis acids have been used as the catalyst in dichloro-
methane, but all of these tested acids did not work well
(Entries 10－15).
Table 1 Conversion of compound 1a to compound 2a under
various conditions
4
6
MeO
3
4
5
2
MeO
MeO
1
O
base
7
MeO
1
solvent, oC
T
2a
1a
Entry
Solvent
Base (equiv.) T/℃ t/h Yielda/%
1
2
3
4
5
6
7
8
9
10
11
12
13
DMSOb
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO/EtOAcd
DMSO
DMSO
DMSO
KOH (3)
KOH (2)
KOH (1)
KOH (3)
KOH (3)
NaOH (3)
EtONa (3) 120 1
NaH (4)
Et3N (3)
120 1
120 2
120 4
100 2
93
72c
31c
65c
16c
91
42c
81c
0e
80
3
120 1
80
1
120 3
K2CO3 (3) 120 3
Na2CO3(3) 120 3
Cs2CO3 (3) 120 3
0e
0e
DMSO
0e
EtOH
KOH (3)
78f
2
0e
14
15
16
17
i-PrOH
KOH (3)
KOH (3)
KOH (3)
KOH (3)
82f
2
2
2
0e
0e
0e
0e
n-Propanol
n-Butanol
97f
117f
HOCH2CH2OH
120 2
18
19
20
1,4-Dioxane
DMEg
DMFh
KOH (3)
KOH (3)
KOH (3)
101f
84f
2
2
0e
0e
0e
120 2
a Isolated yields. b Dimethylsulfoxide. c 10%―75% of compound
1a was recovered. d DMSO/EtOAc＝5∶1 (V∶V). e No reaction.
f Refluxing. g 1,2-Dimethoxyethane. h N,N-Dimethylformamide.
The above PTSA-catalyzed cyclization is applicable
to all the fourteen 2-alkenylstilbenes 2a－2n, the corre-
sponding 1,2-disubstituted indenes 3a－3n were ob-
tained in good yields (see Table 4). When the substituent
R3 is H (Table 4, Entries 1－12), the cyclization was
fast in the refluxing chloromethane (40 ℃). When the
substituent R3 is methyl or butyl group (Table 4, Entries
13 and 14), the cyclization was relatively slow, and
should be performed in the refluxing chloroform (61
℃).
A possible mechanism for the acid-catalyzed cycli-
zation of 2-alkenylstilbenes 2 to form indenes 3 was
proposed in Scheme 4. Electrophilic addition of proton
to the vinyl group would first produce carbon cations
I-6, which would then smoothly undergo cyclization to
afford indane cations I-7. Deprotonation of the cations
I-7 would furnish the indenes 3.
Subsequently, we tried the above base-catalyzed
ring-opening of variously substituted isochromans 1, the
corresponding substituted 1-alkenylstilbenes 2 were
accordingly obtained, and the results are summarized in
Table 2. As can be seen from Table 2, a total of fourteen
isochromans 1a－1n were tested for the reaction, condi-
tions A and B were employed for different substrates
according to the patterns of substituents. Both condi-
tions A and B were applicable for the reaction of iso-
chromans 1a－1h (Table 2, Entries 1－8), while only
the condition B was applicable for the reaction of iso-
chromans 1i－1n (Entries 9－14). If condition A was
applied to the reaction of benzyl-halogenated isochro-
mans 1i－1n, halogen atoms (F, Cl, or Br) on benzyls
would be partially replaced by OH. For example, when
condition A was applied to the reaction of isochroman 1l,
compound 2l and compound 5 (Scheme 2) were then
obtained in 46% and 34% yields, respectively.
Intrestingly, it was found that the 1,2-disubstituted
indenes 3 could be readily transformed into the more
A plausible mechanism for the conversion of iso-
Chin. J. Chem. 2015, 33, 1276—1286
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1277

Ding, Shi & Lu
FULL PAPER
stable 2,3-disubstituted indenes 4 (see Scheme 5) via a
base-catalyzed isomerization. When indenes 3a－3n
were heated in pyridine (100 ℃) for 6 h, the more sta-
ble 2,3-disubstituted indenes 4a－4n could be obtained
in almost quantitative yields (＞98%). It was observed
that when 0.5－1.0 equivalent of NaOH or KOH was
Table 2 Conversion of 1-benzylisochromans 1 to 2-alkenylstilbenes 2
4
R2
R3
3
2
O
R2
R1
R3
1
Condition A or B
R1
R4
R4
2
1
Entry
1
R1
R2
R3
R4
H
Conditiona
A (or B)
A (or B)
A (or B)
A (or B)
A (or B)
A (or B)
A (or B)
A (or B)
B
Product 2
2a
Yieldb/%
93 (81)c
90 (75)c
92 (79)c
88 (76)c
94 (82)c
84 (74)c
92 (80)c
93 (83)c
86
1
OMe
OMe
OMe
OMe
OMe
OMe
H
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
H
1a
1b
1c
1d
1e
1f
2
H
4-OMe
3-OMe
4-OBn
3,4-(OMe)2
3-CF3
H
2b
3
H
2c
4
H
2d
5
H
2e
6
H
2f
7
H
1g
1h
1i
2g
8
H
H
2-OEt
2,4-(Cl)2
2-Cl
2h
9
OMe
OMe
OMe
OMe
OMe
OMe
H
2i
10
11
12
13
14
H
B
80
1j
2j
H
4-Br
B
82
1k
1l
2k
H
4-F
B
80
2l
Me
n-Bu
2-Cl
B
72
1m
1n
2m
2n
2-Cl
B
70
a Condition A: KOH (3.0 equiv.), DMSO, 120 ℃, 1 h; Condition B: NaH (4.0 equiv.), DMSO/EtOAc (5∶1, V∶V), 80 ℃, 1 h. b Isolated
yield. c The yields in parenthesis were obtained under the condition B.
Scheme 2 Structure of some related compounds
MeO
MeO
OAc
MeO
MeO
MeO
MeO
OH
Cl
Cl
OH
OMe
5
6
7
Scheme 3 Plausible mechanism for the conversion of isochromans 1 to 2-alkenylstilbenes 2
R2
R1
R3
OH
R2
R1
R3
OH
R2
R1
R3
β-elimination
KOH
- OH
O
Path a
(condition A)
R4
R4
R4
R2
R1
R3
I-2
I-3
I-1
Path
(condition B)
b
R4
KOH or NaH
2
R2
R1
R3
OAc
R2
R1
R3
R2
R1
R3
O
OAc
NaH
- OAc
R4
I-5
1
R4
I-4
R4
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Chin. J. Chem. 2015, 33, 1276—1286

Synthesis and Acid-Catalyzed Cyclization of 2-Alkenylstilbenes
Table 3 Conversion of compound 2a to compound 3a
used as the catalyst, this isomerization also worked at 65
－80 ℃ in some polar solvents such as methanol,
ethanol, propanol, isopropanol and DMSO albeit only in
moderate yields. As can be seen in Scheme 5, the indene
ions I-8 might be involved during the isomerization.
MeO
MeO
acid
solvent
MeO
MeO
oC
T
3a
2a
Conclusions
Entry Solvent
Acid (equiv.)
PTSAb (0.1)
PTSAb (0.1)
PTSAb (0.05)
PTSAb (0.02)
PTSAb (0.5)
PTSAb (0.5)
PTSAb (0.5)
PTSAb (0.2)
PTSAb (0.5)
CF3CO2H (0.5)
HCl (0.5)
T/℃ t/h Yielda/%
1
2
CHCl3
CH2Cl2
CH2Cl2
CH2Cl2
DMF
61c
40c
40c
40c
80
1
1
3
5
2
2
2
2
2
2
3
2
2
2
2
83
85
In summary, a new synthetic approach to highly sub-
stituted indenes has been developed. 1-Benzyl-iso-
chromans 1 were efficiently transformed to 2-alkenyl-
stilbenes 2 via a base-catalyzed ring-opening under
condition A (KOH in DMSO at 120 ℃) or condition B
(NaH in DMSO/EtOAc at 80 ℃). Both conditions A
and B were applicable for non-halogenated 1-benzyliso-
chromans 1a－1h, only condition B was applicable for
halogenated 1-benzylisochromans 1i－1n in order to
avoid replacement of halogen atoms on the benzyl
groups. 2-Alkenylstilbenes 2 were readily converted to
indenes 3 in high yields via an acid-catalyzed cycliza-
tion, and p-toluenesulfonic acid (PTSA) was found to be
the best catalyst for the cyclization. Finally, 1,2-disub-
stituted indenes 3 were smoothly isomerized into the
more stable 2,3-disubstituted indenes 4 in pyridine at
100 ℃ in almost quantitative yields. The above-de-
scribed method can be easily scaled up, and would be
quite practical and useful for the synthesis of highly
substituted indenes due to some advantages such as high
efficiency, environment-friendly reaction conditions,
free of toxic transition metal catalysts or other expen-
sive reagents.
3
72d
43d
11d
57d
32d
79d
38d
29d
25d
9e
4
5
6
EtOAc
EtOH
77c
78c
50
7
8
Toluene
THF
9
66c
40c
40c
25
10
11
12
13
14
15
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
BF3•OEt2 (0.5)
FeCl3 (0.5)
25
7e
SnCl4 (0.5)
25
12e
16e
ZnCl2 (0.5)
25
a Isolated yield. b para-Toluenesulfonic acid. c Refluxing. d 15%－
65% of compound 2a was recovered. The reaction was compli-
e
cated.
Table 4 PTS-catalyzed cyclization of various substituted 2-alkenylstibenes 2 to give the corresponding indenes 3
R3
R2
R1
R3
R2
R1
R4
R4
3
2
Entry
1
2
R1
R2
R3
H
R4
Solvent
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CHCl3
PTSA (equiv.)
T/℃ t/h
40b
3
Yielda/%
3a 85
0.5 3b 88
1 3c 83
2a OMe
2b OMe
2c OMe
2d OMe
2e OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
H
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.1
0.1
0.1
0.1
0.25
0.25
1
2
H
4-OMe
3-OMe
4-OBn
3,4-(OMe)2
3-CF3
H
40b
40b
40b
40b
40b
40b
40b
40b
40b
40b
40b
61b
61b
3
H
4
H
0.5 3d 92
0.5 3e 91
5
H
6
2f
2g
2h
2i
OMe
H
H
1
2
2
1
1
1
1
3f
75
7
H
3g 82
3h 84
8
H
H
2-OEt
2,4-(Cl)2
2-Cl
9
OMe
OMe
H
3i
3j
81
80
10
11
12
13
14
2j
H
2k OMe
2l OMe
H
4-Br
3k 89
3l 79
H
4-F
2m OMe
Me
n-Bu
2-Cl
2.5 3m 92
2.5 3n 91
2n OMe
2-Cl
CHCl3
a Isolated yield. b Refluxing.
Chin. J. Chem. 2015, 33, 1276—1286
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Ding, Shi & Lu
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Scheme 4 Mechanism for the conversion of compounds 2 to 3
R3
H
R3
R2
R1
R3
R2
R1
R3
H
R2
R1
R2
R1
- H
R4
R4
R4
R4
I-7
3
2
I-6
Scheme 5 Conversion of 1,2-disubstituted indenes 3 to the more stable 2,3-disubstituted indenes 4
R3
R3
R3
R2
R1
R2
R1
H
R2
R1
Pyridine
100 oC, 6 h
R4
R4
R4
> 98% yields
for 4a - 4n
3a - 3n
4a 4n
I-8
-
Experimental
mL), a dispersion of sodium hydride (800.0 mg, 60%
w/w, 20.00 mmol) in mineral oil was then added in por-
tions. The mixture was heated to 80 ℃, and then stirred
at this temperature for around 1 h. The reaction was
monitored by TLC (EtOAc/hexane, 1∶10, V∶V). After
the reaction was complete, the mixture was cooled
down to room temperature. Ethyl acetate (80 mL) and
an aqueous HCl solution (0.5 mol/L, 80 mL) were
added, the mixture was then vigorously stirred for 10
min. Two phases were separated, and the aqueous phase
was extracted once more with ethyl acetate (30 mL).
Organic extracts were combined, and dried over anhy-
drous MgSO4. Evaporation of solvent under vacuum
gave the crude product, which was purified by flash
chromatography (EtOAc/hexane, 1 ∶ 20) to afford
compound 2i (1.441 g, 4.299 mmol) in 86% yield.
General methods
1H NMR and 13C NMR spectra were acquired on a
Bruker AM-400 instrument, chemical shifts were given
on the delta scale as parts per million with tetramethyl-
silane (TMS) as the internal standard. IR spectra were
recorded on Nicolet Magna IR-550 spectrometer. Mass
spectra were recorded on HP5989A equipment. Melting
points were determined on a Mel-TEMP II apparatus.
Column chromatography was performed on silica gel
(Qingdao Ocean Chemical Corp.). All chemicals were
analytically pure, and were used as such from commer-
cial suppliers. Starting compounds 1-benzyl-isochro-
mans 1a－1n could be readily prepared via oxa-Pictet-
Spengler reaction,[14] the experimental procedures for
the preparation of these compounds are included in the
supporting information.
Characterization data of 2-alkenylstilbenes 2a－2n
(E)-1,2-Dimethoxy-4-styryl-5-vinylbenzene
2a
White crystals, m.p. 100－101 ℃. 1H NMR (400 MHz,
CDCl3, TMS) δ: 3.93 (s, 3H), 3.96 (s, 3H), 5.31 (d, J＝
10.9 Hz, 1H), 5.57 (d, J＝17.3 Hz, 1H), 6.89 (d, J＝
16.1 Hz, 1H), 6.98 (s, 1H), 7.07 (s, 1H), 7.08 (dd, J1＝
17.3 Hz, J2＝10.9 Hz, 1H), 7.26 (t, J＝7.3 Hz, 1H),
7.32－7.43 (m, 3H), 7.51 (d, J＝7.7 Hz, 2H); 13C NMR
(100 MHz, CDCl3) δ: 148.97, 148.91, 137.65, 134.37,
129.40, 129.34, 128.73, 128.44, 127.52, 126.44, 126.08,
114.93, 108.82, 108.54, 55.98, 55.92. IR (KBr film) ν:
2931, 2827, 1597, 1509, 1270, 1208, 1182, 1099, 960,
897, 761 cm−1. HRMS (EI): calcd for C18H18O2 [M]＋:
266.1307; found 266.1305.
(E)-1,2-Dimethoxy-4-(4-methoxystyryl)-5-vinyl-
benzene 2b White crystals, m.p. 73－74 ℃; 1H NMR
(400 MHz, CDCl3, TMS) δ: 3.84 (s, 3H), 3.93 (s, 3H),
3.95 (s, 3H), 5.29 (d, J＝11.0 Hz, 1H), 5.56 (d, J＝17.3
Hz, 1H), 6.84 (d, J＝16.0 Hz, 1H), 6.91 (d, J＝8.0 Hz,
2H), 6.98 (s, 1H), 7.05 (s, 1H), 7.08 (dd, J1＝17.3 Hz,
J2＝11.0 Hz, 1H), 7.24 (d, J＝16.0 Hz, 1H), 7.45 (d,
J＝8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 159.21,
148.95, 148.63, 134.44, 130.47, 129.05, 128.91, 128.78,
127.62 (2C), 123.97, 114.63, 114.14 (2C), 108.78,
108.41, 55.96, 55.91, 55.35. IR (KBr film) ν: 2934,
2830, 1604, 1512, 1277, 1244, 1209, 1180, 1099, 1033,
997, 953 cm−1. HRMS (EI): calcd for C19H20O3 [M]＋:
Typical procedure for the conversion of 1-benzyl-
isochromans 1a－1h to 2-alkenylstilbenes 2a－2h
under condition A (see Table 2)
Isochroman 1a (1.422 g, 5.001mmol) was dissolved
in DMSO (15 mL), and the powdered KOH (0.845 g,
15.06 mmol) was then added. The mixture was heated to
120 ℃, and then stirred at this temperature for around 1
h. The reaction was monitored by TLC (EtOAc/hexane,
1∶10). After the reaction was complete, the mixture
was cooled down to room temperature. Ethyl acetate (60
mL) and an aqueous HCl solution (0.5 mol/L, 60 mL)
were added, and the mixture was vigorously stirred for
10 min. Two phases were separated, and the aqueous
phase was extracted once more with ethyl acetate (30
mL). Organic extracts were combined, and dried over
anhydrous MgSO4. Evaporation of solvent under vac-
uum gave the crude product, which was purified by
flash chromatography (EtOAc/hexane, 1∶20) to afford
compound 2a (1.238, 4.650 mmol) in 93% yield.
Typical procedure for the conversion of 1-benzyl-
isochromans 1a－1n to 2-alkenylstilbenes 2a－2n
under condition B (see Table 2)
Isochroman 1i (1.766 g, 5.000 mmol) was dissolved
in a mixed solvent of DMSO (15 mL) and EtOAc (3
1280
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© 2015 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2015, 33, 1276—1286

Synthesis and Acid-Catalyzed Cyclization of 2-Alkenylstilbenes
296.1412; found 296.1414.
108.61, 55.98, 55.91; IR (KBr film) ν: 2932, 2829, 1597,
1512, 1325, 1210, 1158, 1112, 1099, 898 cm−1. HRMS
(EI): calcd for C19H17F3O2 [M]＋ : 334.1181; found
334.1178.
(E)-1,2-Dimethoxy-4-(3-methoxystyryl)-5-vinyl-
benzene 2c Colorless oil. 1H NMR (400 MHz, CDCl3,
TMS) δ: 3.84 (s, 3H), 3.92 (s, 3H), 3.95 (s, 3H), 5.30
(dd, J1＝11.0 Hz, J2＝1.2 Hz, 1H), 5.56 (dd, J1＝17.3
Hz, J2＝1.2 Hz, 1H), 6.81 (dd, J1＝7.8 Hz, J2＝2.5 Hz,
1H), 6.85 (d, J＝16.1 Hz, 1H), 6.98 (s, 1H), 7.05 (s, 1H),
7.02－7.14 (m, 3H), 7.27 (dd, J1＝7.9 Hz, J2＝7.8 Hz,
1H), 7.37 (d, J＝16.1 Hz, 1H); 13C NMR (100 MHz,
CDCl3) δ: 159.93, 148.99, 139.13, 134.35, 129.67 (2C),
129.47, 129.21, 128.34, 126.43, 119.13, 114.95, 113.02,
111.82, 108.89, 108.62, 55.98, 55.92, 55.28; IR (neat) ν:
2997, 2935, 2833, 1599, 1510, 1463, 1265, 1205, 1157,
1104, 1044, 863 cm−1. HRMS (EI): calcd for C19H20O3
[M]＋: 296.1412; found 296.1412.
(E)-4-Methoxy-1-styryl-2-vinylbenzene
2g
Colorless oil. 1H NMR (400 MHz, CDCl3, TMS) δ: 3.90
(s, 3H), 5.45 (dd, J1＝11.0 Hz, J2＝1.3 Hz, 1H), 5.72
(dd, J1＝17.4 Hz, J2＝1.3 Hz, 1H), 6.92 (dd, J1＝8.6 Hz,
J2＝2.7 Hz, 1H), 6.95 (d, J＝15.8 Hz, 1H), 7.07 (d, J＝
2.7 Hz, 1H), 7.16 (dd, J1＝17.4 Hz, J2＝11.0 Hz, 1H),
7.31 (t, J＝7.3 Hz, 1H), 7.41 (d, J＝15.6 Hz, 1H), 7.42
(dd, J1＝7.3 Hz, J2＝7.4 Hz, 1H), 7.56 (d, J＝7.4 Hz,
2H), 7.57 (d, J＝17.4 Hz, 1H); 13C NMR (100 MHz,
CDCl3) δ: 159.28, 137.85, 137.79, 135.05, 129.33,
128.71 (2C), 128.62, 127.62, 127.41, 126.44 (2C),
126.06, 116.80, 114.16, 111.35, 55.35; IR (neat) ν: 3026,
2937, 2833, 1599, 1561, 1496, 1288, 1265, 1245, 1165,
1030, 962, 915 cm−1. HRMS (EI): calcd for C17H16O
[M]＋: 236.1201; found 236.1202.
(E)-1-(4-(Benzyloxy)styryl)-4,5-dimethoxy-2-vinyl-
benzene 2d White crystals, m.p. 108－109 ℃. H
1
NMR (400 MHZ, CDCl3, TMS) δ: 3.92 (s, 3H), 3.95 (s,
3H), 5.09 (s, 2H), 5.29 (d, J＝11.1 Hz, 1H), 5.56 (d, J＝
17.3 Hz, 1H), 6.83 (d, J＝16.1 Hz, 1H), 6.97 (d, J＝8.2
Hz, 2H), 6.98 (s, 1H), 7.04 (s, 1H), 7.07 (dd, J1＝17.3
Hz, J2＝11.1 Hz, 1H), 7.24 (d, J＝16.1 Hz, 1H), 7.33 (t,
J＝7.2 Hz, 1H), 7.39 (dd, J1＝7.4 Hz, J2＝7.2 Hz, 2H),
7.43 (d, J＝7.4 Hz, 2H), 7.44 (d, J＝8.2 Hz, 2H); 13C
NMR (100 MHz, CDCl3) δ: 158.53, 149.13, 148.83,
137.04, 134.57, 130.87, 129.25, 129.00, 128.92, 128.69
(2C), 128.09, 127.71 (2C), 127.56 (2C), 124.26, 115.23
(2C), 114.72, 109.08, 108.72, 70.18, 56.06, 56.02; IR
(KBr film) ν: 2930, 2830, 1604, 1511, 1457, 1275, 1251,
1209, 1179, 1100, 1028, 841 cm−1. HRMS (EI): calcd
for C25H24O3 [M]＋: 372.1725; found 372.1723.
(E)-1-(2-Ethoxystyryl)-4-methoxy-2-vinylbenzene
2h Colorless oil. 1H NMR (400 MHz, CDCl3, TMS) δ:
1.37 (t, J＝7.0 Hz, 3H), 3.74 (s, 3H), 3.98 (q, J＝7.0 Hz,
2H), 5.27 (dd, J1＝11.0 Hz, J2＝1.2 Hz, 1H), 5.55 (dd,
J1＝17.4 Hz, J2＝1.2 Hz, 1H), 6.73－6.81 (m, 2H), 6.85
(dd, J1＝7.6 Hz, J2＝7.5 Hz, 1H), 6.91 (d, J＝2.5 Hz,
1H), 7.02 (dd, J1＝17.4 Hz, J2＝11.0 Hz, 1H), 7.11 (dd,
J1＝7.5 Hz, J2＝7.4 Hz, 1H), 7.15 (d, J＝16.3 Hz, 1H),
7.33 (d, J＝16.3 Hz, 1H), 7.42－7.49 (m, 2H); 13C
NMR (100 MHz, CDCl3) δ: 159.09, 156.39, 137.65,
135.22, 129.44, 128.36, 127.65, 126.99, 126.84, 126.47,
124.58, 120.68, 116.45, 114.12, 112.09, 111.20, 63.94,
55.34, 15.00. IR (neat) ν: 2978, 2935, 2834, 1600, 1561,
1493, 1453, 1393, 1289, 1260, 1242, 1045, 970 cm−1.
HRMS (EI): calcd for C19H20O2 [M]＋: 280.1463; found
280.1463.
(E)-1-(2,4-Dichlorostyryl)-4,5-dimethoxy-2-vinyl-
benzene 2i White crystals, m.p. 118－119 ℃.1H
NMR (400 MHz, CDCl3, TMS) δ: 3.96 (s, 3H), 3.98 (s,
3H), 5.34 (dd, J1＝11.0 Hz, J2＝1.2 Hz, 1H), 5.59 (dd,
J1＝17.3 Hz, J2＝1.2 Hz, 1H), 7.00 (s, 1H), 7.07 (dd,
J1＝17.3 Hz, J2＝11.0 Hz, 1H), 7.09 (s, 1H), 7.20 (d,
J＝16.1 Hz, 1H), 7.25 (dd, J1＝8.5 Hz, J2＝2.1 Hz, 1H),
7.35 (d, J＝16.1 Hz, 1H), 7.42 (d, J＝2.1 Hz, 1H), 7.60
(d, J＝8.5 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ:
149.43, 149.05, 134.40, 134.20, 133.68, 133.24, 129.29,
129.52, 129.18, 127.82, 127.30, 127.20, 124.11, 115.44,
109.03, 108.85, 56.01, 55.92. IR (KBr film) ν: 2936,
1600, 1510, 1466, 1270, 1208, 1188, 1100, 1045, 992,
868 cm−1. HRMS (EI): calcd for C18H16Cl2O2 [M]＋:
334.0527; found 334.0530.
(E)-1-(3,4-Dimethoxystyryl)-4,5-dimethoxy-2-vin-
ylbenzene 2e White crystals, m.p. 93－94 ℃. H
1
NMR (400 MHz, CDCl3, TMS) δ: 3.89 (s, 3H), 3.92 (s,
3H), 3.94 (s, 3H), 3.95 (s, 3H), 5.30 (dd, J1＝11.0 Hz,
J2＝1.0 Hz, 1H), 5.57 (dd, J1＝17.3 Hz, J2＝1.0 Hz,
1H), 6.83 (d, J＝16.0 Hz, 1H), 6.86 (d, J＝8.7 Hz, 1H),
6.98 (s, 1H), 7.01－7.07 (m, 3H), 7.09 (dd, J1＝17.3 Hz,
J2＝11.0 Hz, 1H), 7.24 (d, J＝16.0 Hz, 1H); 13C NMR
(100 MHz, CDCl3) δ: 149.10, 148.96, 148.81, 148.68,
134.40, 130.78, 129.25, 129.03, 128.67, 124.20, 119.57,
114.62, 111.23, 108.88, 108.76, 108.50, 55.93 (2C),
55.89 (2C); IR (KBr film) ν: 3003, 2932, 2838, 1602,
1516, 1464, 1270, 1205, 1157, 1139, 1099, 1021, 948
cm−1. HRMS (EI): calcd for C20H22O4 [M]＋: 326.1518;
found 326.1518.
(E)-1,2-Dimethoxy-4-(3-(trifluoromethyl)styryl)-
5-vinylbenzene 2f White crystals, m.p. 97－98 ℃.
1H NMR (400 MHz, CDCl3, TMS) δ: 3.94 (s, 3H), 3.96
(s, 3H), 5.34 (d, J＝11.0 Hz, 1H), 5.58 (d, J＝17.3 Hz,
1H), 6.90 (d, J＝16.1 Hz, 1H), 6.99 (s, 1H), 7.06 (s, 1H),
7.08 (dd, J1＝17.3 Hz, J2＝11.0 Hz, 1H), 7.44 (d, J＝
16.1 Hz, 1H), 7.43－7.53 (m, 2H), 7.68 (d, J＝7.2 Hz,
1H), 7.73 (s, 1H); 13C NMR (100 MHz, CDCl3) δ:
(E)-1-(2-Chlorostyryl)-4,5-dimethoxy-2-vinylben-
1
zene 2j White crystals, m.p. 109－110 ℃. H NMR
(400 MHz, CDCl3, TMS) δ: 3.94 (s, 3H), 3.96 (s, 3H),
5.32 (d, J＝11.0 Hz, 1H), 5.57 (d, J＝17.3 Hz, 1H),
6.98 (s, 1H), 7.07 (dd, J1＝17.3 Hz, J2＝11.0 Hz, 1H),
7.09 (s, 1H), 7.19 (dd, J1＝7.9 Hz, J2＝7.6 Hz, 1H),
7.26 (d, J＝16.3 Hz, 1H), 7.27 (dd, J1＝8.2 Hz, J2＝7.9
Hz, 1H), 7.36 (d, J＝16.3 Hz, 1H), 7.39 (d, J＝8.2 Hz,
2
149.33, 149.04, 138.45, 134.19, 131.12 (q, JCF＝32.1
Hz, 1C), 129.84, 129.33, 129.11, 127.90, 127.74, 127.71,
1
3
124.18 (q, JCF＝272.3 Hz, CF3), 123.87 (q, JCF＝3.8
3
Hz, 1C), 123.09 (q, JCF＝3.8 Hz, 1C), 115.36, 109.01,
Chin. J. Chem. 2015, 33, 1276—1286
© 2015 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
1281

Ding, Shi & Lu
FULL PAPER
1H), 7.66 (d, J＝7.6 Hz, 1H); 13C NMR (100 MHz,
CDCl3) δ: 149.40, 149.17, 135.90, 134.43, 133.41,
129.93, 129.92, 128.85, 128.50, 128.32, 127.06, 126.66,
125.49, 115.34, 109.10, 109.06, 56.14, 56.06; IR (KBr
film) ν: 3021, 2920, 2833, 1598, 1512, 1449, 1270,
1208, 11 00, 1031, 957, 850, 742 cm−1. HRMS (EI):
calcd for C18H17ClO2 [M]＋: 300.0917; found 300.0915.
(E)-1-(4-Bromostyryl)-4,5-dimethoxy-2-vinylben-
1H), 7.19 (dd, J1＝7.7 Hz, J2＝7.6 Hz, 1H), 7.25 (d, J＝
16.1 Hz, 1H), 7.27 (dd, J1＝8.0 Hz, J2＝7.6 Hz, 1H),
7.35 (d, J＝16.1 Hz, 1H), 7.39 (d, J＝8.0 Hz, 1H), 7.67
(d, J＝7.7 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ:
149.21, 148.34, 135.94, 133.23, 133.04, 130.23, 129.79,
129.16, 128.22, 127.51, 127.05, 126.90, 126.47, 124.78,
109.33, 109.02, 56.01, 55.92, 33.06, 31.68, 22.33, 13.98.
IR (KBr film) ν: 2992, 2911, 2826, 1602, 1501, 1436,
1270, 1202, 1101, 1010, 954, 761 cm−1. HRMS (EI):
calcd for C22H25ClO2 [M]＋: 356.1543; found 356.1546.
1
zene 2k White crystals, m.p. 102－103 ℃. H NMR
(400 MHz, CDCl3, TMS) δ: 3.93 (s, 3H), 3.95 (s, 3H),
5.32 (d, J＝11.0 Hz, 1H), 5.57 (d, J＝17.3 Hz, 1H),
6.81 (d, J＝16.0 Hz, 1H), 6.97 (s, 1H), 7.04 (s, 1H),
7.06 (dd, J1＝17.3 Hz, J2＝11.0 Hz, 1H), 7.36 (d, J＝
8.2 Hz, 2H), 7.37 (d, J＝16.0 Hz, 1H), 7.47 (d, J＝8.2
Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 149.14,
149.02, 136.61, 134.26, 131.77 (2C), 129.62, 128.03,
127.96, 127.87 (2C), 126.80, 121.13, 115.17, 109.00,
108.55, 55.99, 55.92; IR (KBr film) ν: 2922, 2838, 1598,
1509, 1469, 1268, 1207, 1183, 1099, 1001, 962, 863
Typical procedure for the conversion of 2-alkenyl-
stilbenes 2 to 1,2-disubstituted indenes 3
p-Toluenesulfonic acid (87.00 mg, 0.5052 mmol)
was added into a solution of compound 2a (1.332 g,
5.001mmol) in CH2Cl2 (65 mL). The solution was
heated to about 40 ℃, and then stirred at reflux for
around 1 h. The reaction was monitored by TLC
(EtOAc/hexane, 1∶10). After the reaction was com-
plete, the mixture was cooled down to room temperature.
A dilute potassium carbonate aqueous solution (1 mol/L,
10 mL) was added, and the mixture was vigorously
stirred for 10 min. Two phases were separated, and the
aqueous phase was extracted again with CH2Cl2 (25
mL). The organic extracts were combined, and dried
over anhydrous MgSO4. The organic solution was con-
centrated under vacuum to give the crude product,
which was purified by flash chromatography (EtOAc/
hexane, 1∶15) to afford compound 3a (1.132 g, 4.250
mmol) in 85% yield.
cm−1. HRMS (EI): calcd for C18H17BrO2 [M] ＋
344.0412; found 344.0416.
:
(E)-1-(4-Fluorostyryl)-4,5-dimethoxy-2-vinylben-
1
zene 2l White crystals, m.p. 67－68 ℃. H NMR
(400 MHz, CDCl3, TMS) δ: 3.93 (s, 3H), 3.95 (s, 3H),
5.30 (dd, J1＝11.0 Hz, J2＝0.9 Hz, 1H), 5.57 (dd, J1＝
17.3 Hz, J2＝0.9 Hz, 1H), 6.83 (d, J＝16.1 Hz, 1H),
6.98 (s, 1H), 7.00－7.11 (m, 4H), 7.29 (d, J＝16.1 Hz,
1H), 7.46 (dd, J1＝8.6 Hz, J2＝5.5 Hz, 2H); 13C NMR
1
(100 MHz, CDCl3) δ: 162.25 (d, JCF＝247.0 Hz, 1C),
4
148.97, 148.93, 134.31, 133.84 (d, JCF＝3.3 Hz, 1C),
3
129.38, 128.25, 128.11, 127.88 (d, JCF＝7.9 Hz, 2C),
2
Characterization data of 1,2-disubstituted indenes
3a－3n
125.84, 115.63 (d, JCF＝21.6 Hz, 2C), 114.98, 108.85,
108.47, 55.96, 55.91; IR (KBr film) ν: 2935, 2855, 1602,
1512, 1462, 1274, 1229, 1207, 1183, 1099, 995, 861
cm−1. HRMS (EI): calcd for C18H17FO2 [M]＋: 284.1213;
found 284.1211.
5,6-Dimethoxy-1-methyl-2-phenyl-1H-indene 3a
White crystals, m.p. 154－155 ℃. 1H NMR (400 MHz,
acetone-d6, TMS) δ: 1.30 (d, J＝7.5 Hz, 3H), 3.83 (s,
3H), 3.85 (s, 3H), 3.91 (q, J＝7.5 Hz, 1H), 7.05 (s, 1H),
7.11 (s, 1H), 7.19 (s, 1H), 7.26 (t, J＝7.5 Hz, 1H), 7.40
(dd, J1＝8.0 Hz, J2＝7.5 Hz, 2H), 7.58 (d, J＝8.0 Hz,
2H); 13C NMR (100 MHz, CDCl3) δ: 151.37, 148.48,
147.45, 142.25, 136.12, 135.61, 128.61, 126.91, 126.53,
125.57, 107.21, 104.69, 56.34, 56.16, 44.13, 17.58
(CH3); IR (KBr film) ν: 2969, 2930, 1606, 1491, 1465,
1448, 1317, 1220, 1114, 1052, 882, 764 cm−1. HRMS
(EI): calcd for C18H18O2 [M] ＋ : 266.1307; found
266.1309.
1-((E)-2-Chlorostyryl)-4,5-dimethoxy-2-((E)-prop-
1-en-1-yl)benzene 2m White crystals, m.p. 79—80
℃. 1H NMR (400 MHz, CDCl3, TMS) δ: 1.92 (dd, J1＝
6.6 Hz, J2＝1.7 Hz, 3H), 3.92 (s, 3H), 3.94 (s, 3H), 6.03
(dq, J1＝15.5 Hz, J2＝6.6 Hz, 1H), 6.71 (dd, J1＝15.5
Hz, J2＝1.7 Hz, 1H), 6.90 (s, 1H), 7.08 (s, 1H), 7.19 (dd,
J1＝7.8 Hz, J2＝7.7 Hz, 1H), 7.25 (d, J＝16.1 Hz, 1H),
7.27 (dd, J1＝8.0 Hz, J2＝7.7 Hz, 1H), 7.34 (d, J＝16.1
Hz, 1H), 7.38 (d, J＝8.0 Hz, 1H), 7.67 (d, J＝7.8 Hz,
1H); 13C NMR (100 MHz, CDCl3) δ: 149.22, 148.34,
135.93, 133.24, 130.21, 129.80, 129.09, 128.36, 128.27,
127.41 (2C), 126.93, 126.54, 124.79, 109.27, 108.88,
56.01, 55.89, 18.83; IR (KBr film) ν: 2989, 2909, 2830,
5,6-Dimethoxy-2-(4-methoxyphenyl)-1-methyl-
1
1H-indene 3b White crystals, m.p. 145－146 ℃. H
NMR (400 MHz, CDCl3, TMS) δ: 1.32 (d, J＝7.4 Hz,
3H), 3.82 (q, J＝7.4 Hz, 1H), 3.85 (s, 3H), 3.93 (s, 3H),
3.94 (s, 3H), 6.90 (s, 1H), 6.94 (d, J＝8.0 Hz, 2H), 6.95
(s, 1H) 7.03 (s, 1H), 7.45 (d, J＝8.0 Hz, 2H); 13C NMR
(100 MHz, CDCl3) δ: 158.82, 151.14, 148.48, 147.15,
141.94, 136.47, 128.48, 127.73 (2C), 123.79, 114.13
(2C), 107.33, 104.51, 56.39, 56.17, 55.32, 44.18, 17.81;
IR (KBr film) ν: 2957, 2931, 2833, 1605, 1508, 1491,
1315, 1250, 1217, 1110, 1030, 832 cm−1. HRMS (EI):
calcd for C19H20O3 [M]＋: 296.1412; found 296.1412.
1599, 1503, 1438, 1268, 1206, 1104, 1008, 953, 756
＋
cm−1. HRMS (EI): calcd for C19H19ClO2 [M]
314.1074; found 314.1071.
:
1-((E)-2-Chlorostyryl)-2-((E)-hex-1-en-1-yl)-4,5-
1
dimethoxybenzene 2n Colorless oil. H NMR (400
MHz, CDCl3, TMS) δ: 0.94 (t, J＝7.1 Hz, 3H), 1.32－
1.43 (m, 2H), 1.43－1.54 (m, 2H), 2.20－2.30 (m, 2H),
3.93 (s, 3H), 3.95 (s, 3H), 6.01 (dt, J1＝15.6 Hz, J2＝7.1
Hz, 1H), 6.69 (d, J＝15.6 Hz, 1H), 6.91 (s, 1H), 7.08 (s,
1282
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© 2015 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2015, 33, 1276—1286

Synthesis and Acid-Catalyzed Cyclization of 2-Alkenylstilbenes
5,6-Dimethoxy-2-(3-methoxyphenyl)-1-methyl-
1H-indene 3c White crystals, m.p. 123－124 ℃. H
CDCl3, TMS) ν: 1.41 (d, J＝7.5 Hz, 3H), 3.91 (s, 3H),
3.95 (q, J＝7.5 Hz, 1H), 6.90 (dd, J1＝8.2 Hz, J2＝2.2
Hz, 1H), 7.09 (s, 1H), 7.11 (d, J＝2.2 Hz, 1H), 7.32 (t,
J＝7.5 Hz, 1H), 7.35 (d, J＝8.2 Hz, 1H), 7.45 (dd, J1＝
8.1 Hz, J2＝7.5 Hz, 2H), 7.58 (d, J＝8.1 Hz, 1H); 13C
NMR (100 MHz, CDCl3) δ: 158.15, 151.54, 150.48,
136.67, 135.69, 128.65 (2C), 126.96, 126.58 (2C),
125.46, 121.45, 112.09, 109.75, 55.60, 44.21, 17.55; IR
(KBr film) ν: 2933, 1617, 1509, 1557, 1476, 1455, 1432,
1355, 1295, 1228, 1122, 1027, 874 cm−1. HRMS (EI):
calcd for C17H16O [M]＋: 236.1201; found 236.1203.
2-(2-Ethoxyphenyl)-6-methoxy-1-methyl-1H-in-
1
NMR (400 MHz, acetone-d6, TMS) δ: 1.30 (d, J＝7.4
Hz, 3H), 3.83 (s, 3H), 3.85 (s, 6H), 3.89 (q, J＝7.4 Hz,
1H), 6.85 (dd, J1＝8.1 Hz, J2＝1.2 Hz, 1H), 7.04 (s, 1H),
7.07－7.17 (m, 3H), 7.18 (s, 1H), 7.31 (dd, J1＝8.1 Hz,
J2＝7.9 Hz, 1H); 13C NMR (100 MHz, acetone-d6) δ:
160.10, 151.08, 149.12, 148.23, 142.49, 137.08, 136.11,
129.55, 125.99, 118.97, 112.34, 111.91, 108.09, 105.56,
55.72, 55.52, 54.61, 43.92, 17.23; IR (KBr film) ν: 2983,
2936, 2833, 1604, 1578, 1490, 1459, 1322, 1218, 1113,
1052, 877, 785 cm−1. HRMS (EI): calcd for C19H20O3
[M]＋: 296.1412; found 296.1410.
1
dene 3h Colorless oil. H NMR (400 MHz, CDCl3,
2-(4-(Benzyloxy)phenyl)-5,6-dimethoxy-1-methyl-
1H-indene 3d White crystals, m.p. 165－166 ℃. H
TMS) δ: 1.32 (d, J＝7.5 Hz, 3H), 1.52 (t, J＝7.0 Hz,
3H), 3.90 (s, 3H), 4.08－4.23 (m, 3H), 6.87 (dd, J1＝8.2
Hz, J2＝2.2 Hz, 1H), 6.98 (d, J＝8.0 Hz, 1H), 7.02 (dd,
J1＝7.7 Hz, J2＝7.6 Hz, 1H), 7.08 (d, J＝2.2 Hz, 1H),
7.20 (s, 1H), 7.27 (dd, J1＝8.0 Hz, J2＝7.7 Hz, 1H),
7.33 (d, J＝8.2 Hz, 1H), 7.42 (d, J＝7.6 Hz, 1H); 13C
NMR (100 MHz, CDCl3) δ: 157.95, 156.55, 151.43,
148.46, 137.18, 129.82, 128.14, 128.02, 125.19, 121.26,
120.60, 112.14, 111.82, 109.42, 63.87, 55.59, 45.88,
17.12, 14.96; IR (neat) ν: 2976, 1597, 1490, 1478, 1451,
1289, 1242, 1124, 1036, 918 cm−1. HRMS (EI): calcd
for C19H20O2 [M]＋: 280.1463; found 280.1465.
1
NMR (400 MHz, CDCl3, TMS) δ: 1.36 (d, J＝7.5 Hz,
3H), 3.84 (q, J＝7.5 Hz, 1H), 3.95 (s, 3H), 3.97 (s, 3H),
5.13 (s, 2H), 6.93 (s, 1H), 6.98 (s, 1H), 7.05 (d, J＝8.9
Hz, 2H), 7.07 (s, 1H), 7.37 (t, J＝7.1 Hz, 1H), 7.40－
7.53 (m, 6H); 13C NMR (100 MHz, CDCl3) δ: 158.04,
151.08, 148.47, 147.17, 141.95, 137.00, 136.43, 128.73,
128.63 (2C), 128.02, 127.73 (2C), 127.50 (2C), 123.90,
115.06 (2C), 107.31, 104.50, 70.10, 56.38, 56.16, 44.17,
17.81; IR (KBr film) ν: 2968, 2932, 1603, 1555, 1490,
1456, 1335, 1315, 1245, 1218, 1109, 830, 743 cm−1.
HRMS (EI): calcd for C25H24O3 [M]＋: 372.1725; found
372.1728.
2-(2,4-Dichlorophenyl)-5,6-dimethoxy-1-methyl-
1
1H-indene 3i White crystals, m.p. 129－130 ℃. H
2-(3,4-Dimethoxyphenyl)-5,6-dimethoxy-1-meth-
yl-1H-indene 3e White crystals, m.p. 139－140 ℃.
1H NMR (400 MHz, acetone-d6, TMS) δ: 1.29 (d, J＝
7.5 Hz, 3H), 3.82 (s, 3H), 3.83 (s, 3H), 3.84 (s, 3H),
3.85 (q, J＝7.5 Hz, 1H), 3.88 (s, 3H), 6.97 (d, J＝8.3
Hz, 1H), 6.99 (s, 1H), 7.00 (s, 1H), 7.07 (dd, J1＝8.3 Hz,
J2＝1.7 Hz, 1H), 7.15 (s, 1H), 7.20 (d, J＝1.7 Hz, 1H);
13C NMR (100 MHz, acetone-d6) δ: 151.28, 149.64,
149.10, 149.00, 147.86, 142.20, 136.54, 128.79, 124.00,
119.21, 112.03, 110.38, 108.25, 105.34, 55.78, 55.54,
55.28, 55.25, 43.89, 17.55; IR (KBr film) ν: 2960, 2835,
1599, 1554, 1511, 1491, 1463, 1320, 1240, 1215, 1113,
1022, 852 cm−1. HRMS (EI): calcd for C20H22O4 [M]＋:
326.1518; found 326.1521.
NMR (400 MHz, CDCl3, TMS) δ: 1.22 (d, J＝7.5 Hz,
3H), 3.95 (s, 3H), 3.96 (s, 3H), 4.11 (q, J＝7.5 Hz, 1H),
7.01 (s, 1H), 7.048 (d, J＝5.6 Hz, 1H), 7.050 (d, J＝5.6
Hz, 1H), 7.277 (s, 1H), 7.280 (s, 1H), 7.49 (s, 1H); 13C
NMR (100 MHz, CDCl3) δ: 148.53, 148.01, 147.89,
141.86, 135.58, 133.79, 133.37, 132.97, 131.59, 130.72,
130.15, 127.04, 106.95, 105.01, 56.32, 56.18, 46.27,
16.23; IR (KBr film) ν: 2959, 2923, 1606, 1564, 1495,
1463, 1333, 1220, 1117, 1057, 1010, 890 cm−1. HRMS
(EI): calcd for C18H16Cl2O2 [M]＋ : 334.0527; found
334.0523.
2-(2-Chlorophenyl)-5,6-dimethoxy-1-methyl-1H-
indene 3j White crystals, m.p. 117－118 ℃. 1H
NMR (400 MHz, acetone-d6, TMS) δ: 1.17 (d, J＝7.5
Hz, 3H), 3.84 (s, 3H), 3.86 (s, 3H), 4.14 (q, J＝7.5 Hz,
1H), 7.07 (s, 1H), 7.09 (s, 1H), 7.20 (s, 1H), 7.31 (dd,
J1＝7.9 Hz, J2＝7.6 Hz, 1H), 7.38 (dd, J1＝7.6 Hz, J2＝
7.5 Hz, 1H), 7.47 (d, J＝7.5 Hz, 1H), 7.51 (d, J＝7.9 Hz,
1H); 13C NMR (100 MHz, acetone-d6) δ: 149.12, 148.76,
148.46, 141.94, 135.83, 135.15, 132.21, 131.18, 130.38,
130.25, 128.24, 127.07, 107.89, 105.79, 55.70, 55.53,
46.11, 15.76; IR (KBr film) ν: 2964, 2925, 2867, 1607,
1494, 1467, 1334, 1220, 1117, 1051, 1010, 889 cm−1.
HRMS (EI): calcd for C18H17ClO2 [M]＋: 300.0917;
found 300.0914.
5,6-Dimethoxy-1-methyl-2-(3-(trifluoromethyl)-
1
phenyl)-1H-indene 3f Colorless oil. H NMR (400
MHz, acetone-d6, TMS) δ: 1.31 (d, J＝7.5 Hz, 3H), 3.83
(s, 3H), 3.86 (s, 3H), 3.98 (q, J＝7.5 Hz, 1H), 7.07 (s,
1H), 7.20 (s, 1H), 7.29 (s, 1H), 7.55－7.66 (m, 2H),
7.83 (d, J＝7.4 Hz, 1H), 7.88 (s, 1H); 13C NMR (100
MHz, acetone-d6) δ: 149.25, 149.21, 148.68, 142.70,
2
136.71, 135.66, 130.49 (q, JCF＝31.8 Hz, 1C), 130.00
(q, 4JCF＝1.1 Hz, 1C), 129.52, 127.75, 124.54 (q, 1JCF＝
271.7 Hz, CF3), 123.04 (q, 3JCF＝3.9 Hz, 1C), 122.68 (q,
3JCF＝3.9 Hz, 1C), 107.93, 105.78, 55.66, 55.51, 43.81,
16.94; IR (KBr film) ν: 2964, 2834, 1609, 1559, 1491,
1465, 1332, 1295, 1221, 1164, 1118, 1074, 875 cm−1.
HRMS (EI): calcd for C19H17F3O2 [M]＋ : 334.1181;
found 334.1183.
2-(4-Bromophenyl)-5,6-dimethoxy-1-methyl-1H-
1
indene 3k White crystals, m.p. 130－131 ℃. H
NMR (400 MHz, acetone-d6, TMS) δ: 1.30 (d, J＝7.4
Hz, 3H), 3.84 (s, 3H), 3.87 (s, 3H), 3.90 (q, J＝7.4 Hz,
1H), 7.06 (s, 1H), 7.17 (s, 1H), 7.19 (s, 1H), 7.53 (d, J＝
8.5 Hz, 1H), 7.58 (d, J＝8.5 Hz, 1H); 13C NMR (100
6-Methoxy-1-methyl-2-phenyl-1H-indene
White crystals, m.p. 69－70 ℃. H NMR (400 MHz,
3g
1
Chin. J. Chem. 2015, 33, 1276—1286
© 2015 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
1283

Ding, Shi & Lu
FULL PAPER
MHz, acetone-d6) δ: 149.68, 149.17, 148.44, 142.55,
135.88, 134.86, 131.62 (2C), 128.25 (2C), 126.63,
120.02, 108.00, 105.63, 55.68, 55.51, 43.78, 17.06; IR
(KBr film) ν: 2966, 2926, 1563, 1545, 1486, 1462, 1328,
1220, 1115, 1051, 1008, 824 cm−1. HRMS (EI): calcd
for C18H17BrO2 [M]＋: 344.0412; found 344.0411.
chromatography (EtOAc/hexane, 1∶15, V∶V) to af-
ford compound 4a (652.5 mg, 2.450 mmol) in 98%
yield.
Characterization data of 2,3-disubstituted indenes
4a－4n
5,6-Dimethoxy-3-methyl-2-phenyl-1H-indene 4a
White crystals, m.p. 146－147 ℃. 1H NMR (400 MHz,
acetone-d6, TMS) δ: 2.28 (s, 3H), 3.67 (s, 2H), 3.83 (s,
3H), 3.87 (s, 3H), 7.04 (s, 1H), 7.15 (s, 1H), 7.26 (t, J＝
7.5 Hz, 1H), 7.41 (dd, J1＝7.6 Hz, J2＝7.5 Hz, 2H),
7.51 (d, J＝7.6 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ:
148.52, 147.43, 140.41, 139.09, 137.74, 134.91, 134.48,
128.38, 128.06, 126.33, 107.84, 103.03, 56.36, 56.26,
40.74, 12.19; IR (KBr film) ν: 2997, 2937, 1606, 1489,
1464, 1319, 1303, 1207, 1139, 1059, 843, 774 cm−1.
HRMS (EI): calcd for C18H18O2 [M]＋: 266.1307; found
266.1307.
2-(4-Fluorophenyl)-5,6-dimethoxy-1-methyl-1H-
indene 3l White crystals, m.p. 147－148 ℃. 1H
NMR (400 MHz, acetone-d6, TMS) δ: 1.29 (d, J＝7.5
Hz, 3H), 3.83 (s, 3H), 3.85 (s, 3H), 3.89 (q, J＝7.5 Hz,
1H), 7.04 (s, 1H), 7.07 (s, 1H), 7.17 (dd, J1＝8.8 Hz, J2
＝8.7 Hz, 2H), 7.18 (s, 1H), 7.61 (dd, J1＝8.7 Hz, J2＝
5.5 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 161.99 (d,
1JCF＝246.7 Hz, 1C), 150.27, 148.53, 147.48, 142.05,
136.02, 131.86 (d, 4JCF＝3.4 Hz, 1C), 128.01 (d, 3JCF＝
2
7.8 Hz, 2C), 125.36, 115.56 (d, JCF＝21.5 Hz, 2C),
107.20, 104.67, 56.34, 56.16, 44.26, 17.52. IR (KBr
film) ν: 2965, 2932, 1600, 1558, 1506, 1491, 1465,
1450, 1328, 1310, 1221, 1115, 837 cm−1. HRMS (EI):
calcd for C18H17FO2 [M]＋: 284.1213; found 284.1211.
2-(2-Chlorophenyl)-1-ethyl-5,6-dimethoxy-1H-
indene 3m White crystals, m.p. 83－84 ℃.1H NMR
(400 MHz, CDCl3, TMS) δ: 0.50 (t, J＝7.4 Hz, 3H),
1.62－1.78 (m, 1H), 1.86－2.00 (m, 1H), 3.93 (s, 3H),
3.94 (s, 3H), 4.23 (t, J＝4.7 Hz, 1H), 6.98 (s, 1H), 7.028
(s, 1H), 7.034 (s, 1H), 7.20 (dd, J1＝7.7 Hz, J2＝7.6 Hz,
1H), 7.28 (dd, J1＝7.8 Hz, J2＝7.6 Hz, 1H), 7.34 (d, J＝
7.8 Hz, 1H), 7.44 (d, J＝7.7 Hz, 1H); 13C NMR (100
MHz, CDCl3) δ: 148.36, 147.54, 147.37, 139.83, 136.88,
135.47, 132.67, 131.52, 130.94, 130.42, 127.97, 126.77,
107.17, 104.80, 56.33, 56.11, 51.86, 23.10, 8.53; IR
(KBr film) ν: 2964, 1606, 1496, 1469, 1453, 1340, 1297,
1220, 1117, 1058, 1035, 888 cm−1. HRMS (EI): calcd
for C19H19ClO2 [M]＋: 314.1074; found 314.1076.
5,6-Dimethoxy-2-(4-methoxyphenyl)-3-methyl-
1
1H-indene 4b White crystals, m.p. 135－136 ℃. H
NMR (400 MHz, acetone-d6, TMS) δ: 2.25 (s, 3H), 3.62
(s, 2H), 3.82 (s, 6H), 3.86 (s, 3H), 6.98 (d, J＝8.7 Hz,
2H), 7.00 (s, 1H), 7.13 (s, 1H), 7.44 (d, J＝8.7 Hz, 2H);
13C NMR (100 MHz, CDCl3) δ: 158.20, 148.48, 147.17,
140.63, 138.77, 134.63, 133.09, 130.40, 129.12 (2C),
113.87 (2C), 107.88, 102.87, 56.38, 56.25, 55.31, 40.78,
12.14; IR (KBr film) ν: 2932, 2832, 1607, 1510, 1493,
1461, 1351, 1317, 1251, 1211, 1180, 1035, 847 cm−1.
HRMS (EI): calcd for C19H20O3 [M]＋: 296.1412; found
296.1411.
5,6-Dimethoxy-2-(3-methoxyphenyl)-3-methyl-
1
1H-indene 4c White crystals, m.p. 93－94 ℃. H
NMR (400 MHz, CDCl3, TMS) δ: 2.30 (s, 3H), 3.67 (s,
2H), 3.85 (s, 3H), 3.93 (s, 3H), 3.96 (s, 3H), 6.82 (dd,
J1＝8.0 Hz, J2＝2.1 Hz, 1H), 6.92 (s, 1H), 7.00 (d, J＝
2.1 Hz, 1H), 7.05 (d, J＝7.8 Hz, 1H), 7.08 (s, 1H), 7.32
(dd, J1＝8.0 Hz, J2＝7.8 Hz, 1H); 13C NMR (100 MHz,
CDCl3) δ: 159.57, 148.51, 147.47, 140.33, 139.13,
138.90, 134.86, 134.78, 129.32, 120.68, 114.01, 111.50,
107.79, 103.02, 56.35, 56.26, 55.25, 40.82, 12.24; IR
(KBr film) ν: 2938, 2833, 1600, 1512, 1490, 1458, 1350,
1315, 1255, 1216, 1181, 847 cm−1. HRMS (EI): calcd
for C19H20O3 [M]＋: 296.1412; found 296.1412.
2-(2-Chlorophenyl)-5,6-dimethoxy-1-pentyl-1H-
1
indene 3n Colorless oil. H NMR (400 MHz, CDCl3,
TMS) δ: 0.73 (t, J＝6.9 Hz, 3H), 0.82－0.96 (m, 1H),
0.96－1.18 (m, 5H), 1.53－1.70 (m, 1H), 1.76－1.90
(m, 1H), 3.92 (s, 3H), 3.94 (s, 3H), 4.22 (t, J＝5.0 Hz,
1H), 6.98 (s, 1H), 6.99 (s, 1H), 7.04 (s, 1H), 7.20 (dd,
J1＝7.8 Hz, J2＝7.6 Hz, 1H), 7.27 (dd, J1＝7.6 Hz, J2＝
7.5 Hz, 1H), 7.33 (d, J＝7.5 Hz, 1H), 7.44 (d, J＝7.8 Hz,
1H); 13C NMR (100 MHz, CDCl3) δ: 148.34, 147.96,
147.46, 140.30, 136.67, 135.55, 132.68, 131.09, 130.94,
130.37, 127.97, 126.74, 107.31, 104.79, 56.36, 56.11,
51.12, 31.92, 30.23, 23.99, 22.29, 13.90; IR (neat) ν:
2-(4-(Benzyloxy)phenyl)-5,6-dimethoxy-3-methyl-
1
1H-indene 4d White crystals, m.p. 155－156 ℃. H
NMR (400 MHz, CDCl3, TMS) δ: 2.27 (s, 3H), 3.63 (s,
2H), 3.92 (s, 3H), 3.96 (s, 3H), 5.10 (s, 2H), 6.90 (s, 1H),
7.02 (d, J＝8.2 Hz, 2H), 7.07 (s, 1H), 7.30－7.44 (m,
5H), 7.46 (d, J＝7.3 Hz, 2H); 13C NMR (100 MHz,
CDCl3) δ: 157.45, 148.50, 147.20, 140.63, 138.73,
137.07, 134.65, 133.19, 130.67, 129.14 (2C), 128.63
(2C), 128.00, 127.50 (2C), 114.82 (2C), 107.89, 102.89,
70.10, 56.39, 56.26, 40.78, 12.19; IR (KBr film) ν: 2919,
2861, 1604, 1580, 1492, 1467, 1456, 1311, 1233, 1207,
1179, 845 cm−1. HRMS (EI): calcd for C25H24O3 [M]＋:
372.1725; found 372.1723.
2930, 1608, 1491, 1474, 1306, 1255, 1140, 1066, 845
＋
cm−1. HRMS (EI): calcd for C22H25ClO2 [M]
356.1543; found 356.1541.
:
Typical procedure for the conversion of 1,2-disubsti-
tuted indenes 3 to 2,3-disubstituted indenes 4
Compound 3a (665.8 mg, 2.500 mmol) was dis-
solved in pyridine (3 mL), and the resulting solution
was then stirred and heated to 100 ℃. Stirring was con-
tinued at 100 ℃ for approximately 6 h. After that,
pyridine was removed by evaporation under vacuum to
give the crude product, which was purified by flash
2-(3,4-Dimethoxyphenyl)-5,6-dimethoxy-3-meth-
yl-1H-indene 4e White crystals, m.p. 147－148 ℃.
1284
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© 2015 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2015, 33, 1276—1286

Synthesis and Acid-Catalyzed Cyclization of 2-Alkenylstilbenes
1H NMR (400 MHz, acetone-d6, TMS) δ: 2.29 (s, 3H),
3.65 (s, 2H), 3.84 (s, 3H), 3.85 (s, 3H), 3.880 (s, 3H),
3.881 (s, 3H), 7.00 (d, J＝8.3 Hz, 1H), 7.02 (s, 1H),
7.06 (dd, J1＝8.3 Hz, J2＝2.0 Hz, 1H), 7.11 (d, J＝2.0
Hz, 1H), 7.14 (s, 1H); 13C NMR (100 MHz, CDCl3) δ:
148.73, 148.49, 147.79, 147.23, 140.51, 138.90, 134.58,
133.37, 130.75, 120.55, 111.48, 111.26, 107.83, 102.88,
56.36, 56.25, 55.94, 55.92, 40.88, 12.18; IR (KBr film)
ν: 2956, 2837, 1598, 1515, 1492, 1462, 1343, 1300,
1208, 1167, 1055, 1022, 850 cm−1. HRMS (EI): calcd
for C20H22O4 [M]＋: 326.1518; found 326.1515.
Hz, 1H), 7.50 (d, J＝2.1 Hz, 1H); 13C NMR (100 MHz,
CDCl3) δ: 148.50, 147.64, 138.99, 137.52, 136.44,
135.52, 135.42, 134.38, 133.30, 132.07, 129.52, 126.80,
107.83, 103.24, 56.36, 56.28, 41.52, 11.81; IR (KBr
film) ν: 2953, 2911, 2830, 1578, 1492, 1470, 1343,
1302, 1254, 1205, 1143, 1058, 842 cm−1. HRMS (EI):
calcd for C18H16Cl2O2 [M]＋: 334.0527; found 334.0525.
2-(2-Chlorophenyl)-5,6-dimethoxy-3-methyl-1H-
indene 4j White crystals, m.p. 113－114 ℃. 1H
NMR (400 MHz, CDCl3, TMS) δ: 2.03 (s, 3H), 3.66 (s,
2H), 3.92 (s, 3H), 3.96 (s, 3H), 6.94 (s, 1H), 7.09 (s, 1H),
7.20－7.31 (m, 3H), 7.44 (d, J＝8.0 Hz, 1H); 13C NMR
(100 MHz, CDCl3) δ: 148.45, 147.48, 139.25, 137.77,
136.96, 136.82, 135.49, 133.67, 131.34, 129.70, 128.27,
126.43, 107.90, 103.22, 56.38, 56.29, 41.63, 11.78. IR
(KBr film) ν: 2935, 2916, 2831, 1607, 1495, 1469, 1350,
1306, 1252, 1206, 1138, 1058, 834 cm−1. HRMS (EI):
calcd for C18H17ClO2 [M]＋: 300.0917; found 300.0915.
2-(4-Bromophenyl)-5,6-dimethoxy-3-methyl-1H-
5,6-Dimethoxy-3-methyl-2-(3-(trifluoromethyl)-
1
phenyl)-1H-indene 4f Colorless oil. H NMR (400
MHz, CDCl3, TMS) δ: 2.29 (s, 3H), 3.67 (s, 2H), 3.93 (s,
3H), 3.96 (s, 3H), 6.93 (s, 1H), 7.08 (s, 1H), 7.49 (d, J＝
4.6 Hz, 1H), 7.50 (d, J＝4.7 Hz, 1H), 7.60 (dd, J1＝4.6
Hz, J2＝4.7 Hz, 1H), 7.68 (s, 1H); 13C NMR (100 MHz,
CDCl3) δ: 148.62, 147.84, 139.90, 138.43, 137.33,
2
136.18, 134.90, 131.11, 130.77 (q, JCF＝32.0 Hz, 1C),
128.81, 124.51 (q, 3JCF＝3.9 Hz, 1C), 124.29 (q, 1JCF＝
indene 4k White crystals, m.p. 170－171 ℃. H
1
3
272.4 Hz, CF3), 122.80 (q, JCF＝3.9 Hz, 1C), 107.71,
NMR (400 MHz, CDCl3, TMS) δ: 2.29 (s, 3H), 3.64 (s,
2H), 3.95 (s, 3H), 3.98 (s, 3H), 6.94 (s, 1H), 7.09 (s, 1H),
7.32 (d, J＝8.6 Hz, 2H), 7.53 (d, J＝8.6 Hz, 2H); 13C
NMR (100 MHz, CDCl3) δ: 148.58, 147.64, 140.13,
137.69, 136.58, 135.28, 134.79, 131.47 (2C), 129.52
(2C), 120.13, 107.75, 103.06, 56.33, 56.25, 40.56, 12.24.
IR (KBr film) ν: 2931, 2831, 1574, 1488, 1462, 1346,
1311, 1227, 1208, 1143, 1056, 843 cm−1. HRMS (EI):
calcd for C18H17O2Br [M]＋: 344.0412; found 344.0406.
2-(4-Fluorophenyl)-5,6-dimethoxy-3-methyl-1H-
indene 4l White crystals, m.p. 118－119 ℃. 1H NMR
(400 MHz, CDCl3, TMS) δ: 2.29 (s, 3H), 3.65 (s, 2H),
3.95 (s, 3H), 3.99 (s, 3H), 6.94 (s, 1H), 7.10 (s, 1H),
7.11 (dd, J1＝8.8 Hz, J2＝8.7 Hz, 2H), 7.42 (dd, J1＝8.8
Hz, J2＝5.5 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ:
161.48 (d, 1JCF＝246.1 Hz, 1C), 148.54, 147.46, 140.23,
103.16, 56.30, 56.23, 40.58, 12.17; IR (KBr film) ν:
2953, 2835, 1606, 1491, 1445, 1335, 1294, 1207, 1117,
1057, 845, 808 cm−1. HRMS (EI): calcd for C19H17F3O2
[M]＋: 334.1181; found 334.1181.
5-Methoxy-3-methyl-2-phenyl-1H-indene
4g
1
White crystals, m.p. 54－55 ℃. H NMR (400 MHz,
CDCl3, TMS) δ: 2.28 (s, 3H), 3.67 (s, 2H), 3.86 (s, 3H),
6.77 (dd, J1＝8.1 Hz, J2＝2.0 Hz, 1H), 6.93 (d, J＝2.0
Hz, 1H), 7.28 (t, J＝7.5 Hz, 1H), 7.35 (d, J＝8.1 Hz,
1H), 7.41 (dd, J1＝7.8 Hz, J2＝7.5 Hz, 2H), 7.47 (d, J＝
7.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 159.23,
149.03, 141.87, 137.63, 134.67, 134.62, 128.43 (2C),
128.28 (2C), 126.75, 123.80, 110.61, 105.06, 55.60,
40.29, 12.02; IR (KBr film) ν: 2918, 2835, 1605, 1580,
1483, 1442, 1289, 1217, 1174, 1063, 1027, 831 cm−1.
HRMS (EI): calcd for C17H16O [M]＋: 236.1201; found
236.1205.
4
137.99, 134.69, 134.35, 133.80 (d, JCF＝3.3 Hz, 1C),
129.50 (d, 3JCF＝7.8 Hz, 2C), 115.26 (d, 2JCF＝21.3 Hz,
2C), 107.80, 103.01, 56.34, 56.24, 40.85, 12.09. IR
(KBr film) ν: 2921, 2851, 1607, 1571, 1493, 1469, 1347,
1310, 1224, 1210, 1140, 1056, 838 cm−1. HRMS (EI):
calcd for C18H17FO2 [M]＋: 284.1213; found 284.1215.
2-(2-Chlorophenyl)-3-ethyl-5,6-dimethoxy-1H-in-
2-(2-Ethoxyphenyl)-5-methoxy-3-methyl-1H-in-
1
dene 4h Colorless oil. H NMR (400 MHz, CDCl3,
TMS) δ: 1.34 (t, J＝7.0 Hz, 3H), 2.08 (s, 3H), 3.71 (s,
2H), 3.86 (s, 3H), 4.02 (q, J＝7.0 Hz, 2H), 6.76 (dd,
J1＝8.1 Hz, J2＝2.3 Hz, 1H), 6.92 (d, J＝2.3 Hz, 1H),
6.93 (d, J＝7.9 Hz, 1H), 6.95 (dd, J1＝7.7 Hz, J2＝7.6
Hz, 1H), 7.21 (d, J＝7.6 Hz, 1H), 7.25 (dd, J1＝7.9 Hz,
J2＝7.7 Hz, 1H), 7.33 (d, J＝8.1 Hz, 1H); 13C NMR
(100 MHz, CDCl3) δ: 158.97, 156.53, 148.63, 140.65,
135.69, 135.45, 131.08, 128.30, 126.95, 123.59, 120.26,
112.19, 110.16, 104.88, 63.76, 55.61, 40.93, 14.93,
11.89; IR (neat) ν: 2978, 2932, 1606, 1578, 1473, 1447,
1288, 1249, 1216, 1045, 1035, 802, 753 cm−1. HRMS
(EI): calcd for C19H20O2 [M] ＋ : 280.1463; found
280.1461.
1
dene 4m White crystals, m.p. 90－91 ℃. H NMR
(400 MHz, CDCl3, TMS) δ: 1.15 (t, J＝7.6 Hz, 3H),
2.46 (q, J＝7.6 Hz, 2H), 3.64 (s, 2H), 3.92 (s, 3H), 3.96
(s, 3H), 6.98 (s, 1H), 7.10 (s, 1H), 7.21－7.29 (m, 3H),
7.44 (dd, J1＝7.5 Hz, J2＝2.1 Hz, 1H); 13C NMR (100
MHz, CDCl3) δ: 148.30, 147.36, 142.40, 138.07, 137.63,
137.26, 136.01, 133.77, 131.26, 129.60, 128.38, 126.47,
108.06, 103.61, 56.36 (2C), 41.70, 19.55, 13.45; IR
(KBr film) ν: 2961, 2931, 2830, 1607, 1494, 1462, 1317,
1255, 1209, 1140, 1071, 844, 769 cm−1. HRMS (EI):
calcd for C19H19ClO2 [M]＋: 314.1074; found 314.1076.
2-(2-Chlorophenyl)-5,6-dimethoxy-3-pentyl-1H-
2-(2,4-Dichlorophenyl)-5,6-dimethoxy-3-methyl-
1
1H-indene 4i White crystals, m.p. 129－130 ℃. H
1
NMR (400 MHz, CDCl3, TMS) δ: 2.05 (s, 3H), 3.66 (s,
2H), 3.95 (s, 3H), 3.99 (s, 3H), 6.97 (s, 1H), 7.11 (s, 1H),
7.21 (d, J＝8.2 Hz, 1H), 7.29 (dd, J1＝8.2 Hz, J2＝2.1
indene 4n Colorless oil. H NMR (400 MHz, CDCl3,
TMS) δ: 0.81 (t, J＝7.0 Hz, 3H), 1.14－1.31 (m, 4H),
1.48－1.65 (m, 2H), 2.44 (t, J＝7.7 Hz, 2H), 3.64 (s,
Chin. J. Chem. 2015, 33, 1276—1286
© 2015 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
1285

Ding, Shi & Lu
FULL PAPER
Nienhuis, R. J.; Fried, H. E.; Pagani, G. A. J. Org. Chem. 1981, 46,
5125.
2H), 3.92 (s, 3H), 3.95 (s, 3H), 6.97 (s, 1H), 7.09 (s, 1H),
7.21－7.30 (m, 3H), 7.44 (dd, J1＝7.5 Hz, J2＝2.0 Hz,
1H); 13C NMR (100 MHz, CDCl3) δ: 148.26, 147.36,
141.11, 138.41, 138.19, 137.31, 135.98, 133.77, 131.33,
129.61, 128.33, 126.44, 108.00, 103.74, 56.37, 56.33,
41.67, 31.69, 28.19, 26.10, 22.32, 13.94; IR (neat) ν:
2931, 2858, 1608, 1492, 1476, 1361, 1306, 1256, 1210,
1140, 1067, 845, 756 cm−1. HRMS (EI): calcd for
C22H25ClO2 [M]＋: 356.1543; found 356.1545.
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Supporting Information
Experimental procedures for the preparation of
1-benzyl-isochromans 1a－1n; Characterization data of
compounds 1a－1n, 5, 6 and 7; Copies of spectra of 1H
and 13C NMR of compounds 1a－1n, 2a－2n, 3a－3n,
4a－4n, 5, 6 and7.
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Womack, G. B.; Angeles, J. G.; Fanelli, V. E.; Heyer, C. A. J. Org.
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Acknowledgement
We are grateful to the National Natural Science
Foundation of China (No. 20972048) for the financial
support of this work
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(Zhao, X.)
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