Lewis acid catalyzed cascade reactions of diarylvinylidenecyclopropanes and 1,1,3-triarylprop-2-yn-1-ols or their methyl ethers

Article abstract of DOI:10.1002/chem.200800421

The reactions of vinylidenecyclopropanes 1 with 1,1,3-triarylprop2-yn-1-ols or their methyl ethers 2 in the presence of a Lewis acid selectively produce 4-dihydro-1 H-cyclopenta[b]-naphthalene derivatives 3 or 1,2,3,8- tetrahydrocyclopenta[α]indene derivatives 4 depending on the substituents on the cyclopropane. Good to high yields are obtained under mild conditions. A plausible cascade Meyer-Schuster rearrangement and Friedel-Crafts reaction mechanism has been proposed. Moreover, novel functionalized methylenecyclobutene derivatives 5 could also be obtained in moderate to good yields under similar conditions when strongly electron-donating methoxy groups were introduced into the benzene rings of 2.

Full text of DOI:10.1002/chem.200800421

FULL PAPER
DOI: 10.1002/chem.200800421
Lewis Acid Catalyzed Cascade Reactions of Diarylvinylidenecyclopropanes
and 1,1,3-Triarylprop-2-yn-1-ols or Their Methyl Ethers
Min Shi*[a, b] and Liang-Feng Yao[b]
Abstract: The reactions of vinylidene-
cyclopropanes 1 with 1,1,3-triarylprop-
2-yn-1-ols or their methyl ethers 2 in
the presence of a Lewis acid selectively
produce 4-dihydro-1H-cyclopenta[b]-
naphthalene derivatives 3 or 1,2,3,8-tet-
rahydrocyclopenta[a]indene derivatives
4 depending on the substituents on the
cyclopropane. Good to high yields are
obtained under mild conditions.
plausible cascade Meyer–Schuster rear-
rangement and Friedel–Crafts reaction
A
mechanism has been proposed. More-
over, novel functionalized methylene-
cyclobutene derivatives 5 could also be
obtained in moderate to good yields
under similar conditions when strongly
electron-donating methoxy groups
were introduced into the benzene rings
of 2.
Keywords:
tions Friedel–Crafts reaction
indenes
A
N
·
A
·
A
·
Meyer–Schuster rear-
rangement · naphthalenes
Introduction
and by using Lewis acids as the catalysts because the relief
of ring strain can provide a powerful thermodynamic driving
force.[2,3] Thus far, a number of interesting skeletal conver-
sions of VDCPs have been explored. For example, we have
recently reported an interesting Lewis acid catalyzed intra-
molecular rearrangement of diarylvinylidenecyclopropanes
containing one, two, or three substituents at the 1- and/or 2-
position of the corresponding cyclopropane, which gave
6aH-benzo[c]fluorine derivatives in a double-intramolecular
Friedel–Crafts reaction or indene or naphthalene derivatives
Vinylidenecyclopropanes (VDCPs) are highly strained but
readily accessible and stable molecules that can serve as
useful building blocks in organic synthesis (Scheme 1).[1] It is
known that VDCPs can undergo a variety of ring-opening–
cycloaddition reactions upon heating or photoirradiation
via
an
intramolecular
Friedel–Crafts
reaction
(Scheme 2).[3a,b,c] In addition, we have also succeeded in an
effective Lewis acid catalyzed synthesis of substituted
indene derivatives by the intermolecular reactions of arylvi-
nylidenecyclopropanes 1 with acetals under mild conditions,
which is believed to proceed via regioselective addition of
an oxonium intermediate to an arylvinylidenecyclopropane
and a subsequent intramolecular Friedel–Crafts reaction
(Scheme 3).[3d] These results stimulated us to further explore
the transformation of VDCPs under mild conditions. Previ-
ously, we reported that arylmethylenecyclopropanes (MCPs)
can react with 3-methoxy-1,3,3-triarylprop-1-yne or 1,1,3-tri-
arylprop-2-yn-1-ol to give the corresponding functionalized
methylenecyclobutene, cyclobutane, and cyclopropane deriv-
atives in the presence of a Lewis acid (BF3·OEt2) under
mild conditions.[4a] Herein, we wish to present a highly effi-
cient Lewis acid catalyzed cascade intermolecular reaction
of VDCPs 1 with 1,1,3-triarylprop-2-yn-1-ols or their methyl
ethers 2 that selectively produces 4-dihydro-1H-cyclopen-
ta[b]naphthalene derivatives 3 and 1,2,3,8-tetrahydrocyclo-
Scheme 1. Preparation of vinylidenecyclopropanes.
[a]Prof. Dr. M. Shi
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry
Chinese Academy of Sciences
354 Fenglin Road, Shanghai 200032 (China)
Fax : (+86)21-6416-6128
E-mail: Mshi@mail.sioc.ac.cn
[b]Prof. Dr. M. Shi, Mr. L.-F. Yao
East China University of Science and Technology
130 Mei Long Lu, Shanghai 200237 (China)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200800421. It includes spectro-
scopic data (1H and 13C NMR spectroscopic data) and analytic data
of the compounds shown in Tables 1–5, the X-ray crystal structures of
3a and 4d, and detailed descriptions of experimental procedures.
Chem. Eur. J. 2008, 14, 8725 – 8731
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8725

yields, respectively (Table 1,
entries 7 and 8). In THF, a
trace of 3a was obtained
(Table 1, entry 9) and, in tolu-
ene, complex product mixtures
were
entry 10). Other Lewis acids
such as BF3·OEt2, Sc(OTf)3,
Nd(OTf)3, Sn(OTf)2, and the
Brønsted acid (TfOH) were
not as effective as Zr(OTf)4
formed
(Table 1,
ACHTREUNG
A
ACHTREUNG
ACHTREUNG
under the standard conditions
(Table 1, entries 1–6). When
2b was used as a reactant,
complex product mixtures
were obtained at room temper-
ature (208C) or even at 08C by
using Yb(OTf)3 or BF3·OEt2 as
A
a Lewis acid in DCE (Table 1,
entries 12–14). However, the
Lewis acids BF3·OEt2 and Zr-
A
Scheme 2. Lewis acid catalyzed intramolecular rearrangement of VDCPS 1.
3a in 78 and 85% yields, re-
spectively at À208C (Table 1,
entries 15 and 16). Therefore,
on the basis of the above re-
sults, the best reaction condi-
tions for the formation of 3
were to carry out the reaction
of VDCPs 1 with 2a in DCE
at À208C with Zr
C
Scheme 3. Lewis acid catalyzed intermolecular reaction of VDCPs 1 with acetals.
Table 1. Optimization of the reaction conditions of 1a with 2a or 2b.
penta[a]indene derivatives 4 in good to high yields under
mild conditions.
Entry[a] Lewis acid Solvent T [oC] t [h]R
2
Yield of 3a [%][b]
Results and Discussion
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
BF3·OEt2 DCE
À20
À20
À20
À20
À20
À20
8
6
8
6
6
10
6
6
24
12
6
H
H
H
H
H
H
H
H
H
H
H
2a 80
2a 93
2a 70
2a 85
2a 84
2a 75
2a 86
2a 53
Zr
Sc(OTf)3
TfOH
Nd
A
DCE
DCE
DCE
Lewis acid catalyzed reactions of VDCPs 1 with 1,1,3-triar-
ylprop-2-yn-1-ols or their methyl ethers 2: Initial examina-
tions with diphenylvinylidenecyclopropane (1a) and 1,1,3-
triphenylprop-2-yn-1-ol (2a) or its methyl ether (2b) as the
substrates in the presence of various Lewis acids or a
Brønsted acid (TfOH) in a variety of solvents were aimed at
determining the optimal conditions and the results of these
experiments are summarized in Table 1. We found that the
reaction proceeded smoothly in 1,2-dichloroethane (DCE)
to afford 2-benzhydrylidene-3,4,4,9-tetraphenyl-2,4-dihydro-
1H-cyclopenta[b]naphthalene 3a in 93% yield within 6 h at
G
Sn
Zr
Zr
Zr
Zr
Zr
C
CH2Cl2 À20
MeCN À20
THF
À20
2a trace
2a complex
2a 77
toluene À20
DCE
(OTf)3 DCE
(OTf)3 DCE
À25
RT
0
RT
À20
À20
Yb
Yb
N
6
6
6
6
Me 2b complex
Me 2b complex
Me 2b complex
Me 2b 78
G
BF3·OEt2 DCE
BF3·OEt2 DCE
À208C in the presence of Zr
C
Zr
A
DCE
6
Me 2b 85
[a]All reactions were carried out by using 1a (0.2 mmol), 2 (0.24 mmol)
and Lewis acid (10 mol%) in various solvents (2.0 mL). [b]Isolated
yields.
8726
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Chem. Eur. J. 2008, 14, 8725 – 8731

Lewis Acid Catalyzed Reactions of Diarylvinylidenecyclopropanes
FULL PAPER
Table 2. Zr(OTf)4 catalyzed reactions of VCPs with 1,1,3-triphenyl-prop-2-yn-1-ols.
G
Entry
1
R1
R2
R3
R4
R5
R6
2
R7
R8
Yield of 3 [%][a]
1
2
3
4
5
6
7
8
9
1b
1c
1d
1e
1 f
1g
1h
1a
1a
1a
1i
C6H5
C6H5
C6H5
C6H5
p-MeC6H4
p-FC6H4
p-ClC6H4
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
p-MeC6H4
p-FC6H4
C6H5
C6H5
C6H5
C6H5
C6H5
Me
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
2a
2a
2a
2a
2a
2a
2a
2c
2d
2e
2a
2a
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
3b, 80
3c, 80
3d, 65
3e, 80
3 f, 52
3g, 91
p-FC6H4
p-ClC6H4
p-MeC6H4
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
p-FC6H4
p-ClC6H4
p-MeC6H4
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
3h, 88
3i, 65
p-MeC6H4
p-ClC6H4
p-MeOC6H4
Ph
p-MeC6H4
p-ClC6H4
p-MeOC6H4
Ph
3j, 80[b]
3k, 45
3l, 30
10
11
12
C6H5
Me
C6H5
Me
C6H5
1j
p-ClC6H4
C6H5
Ph
Ph
3m, 81 (1:1)[c]
[a]Isolated yields. [b]24% of 1a was recovered. [c]Ratio of two stereoisomers (R 3’ =H, R4 =p-ClC6H4)/(R3’=Cl, R4 =C6H5).
Under these optimal reaction conditions, we next carried
out this interesting reaction by using a variety of starting
materials 1 and 1,1,3-triarylprop-2-yn-1-ols 2. The results are
summarized in Table 2. As can be seen in Table 2, these re-
actions proceeded smoothly to afford the corresponding 4-
dihydro-1H-cyclopenta[b]naphthalene derivatives 3 in mod-
erate to high yields (Table 2). Substituents on the aromatic
rings of 1 have a modest influence on the reaction outcomes.
Adding a moderately electron-donating group, such as a
methyl group, on the aromatic ring of 1 afforded the corre-
sponding 4-dihydro-1H-cyclopenta[b]naphthalene derivative
3 f in somewhat lower yield (52%) (Table 2, entry 5). Simi-
as the substrates under the standard conditions, 1,2,3,8-tetra-
hydrocyclopenta[a]indene derivatives 4 were obtained in
good yields. The reaction conditions have been carefully ex-
amined in a similar way (Table 3). The examination of
Lewis acids and solvent effects revealed that Sc(OTf)3 is the
A
best catalyst in the reaction of 1k with 2b and DCE is the
solvent of choice (Table 3, entries 1–15). Examination of the
reaction temperature also indicated that this reaction should
Table 3. Optimization of the reaction conditions of 1k with 2b or 2a.
larly, introducing
a strongly electron-donating methoxy
group onto the aromatic ring of 2 produced the correspond-
ing 4-dihydro-1H-cyclopenta[b]naphthalene derivative 3k in
45% yield (Table 2, entry 10). The presence of electron-
withdrawing groups, such as fluoro- or chloro-substituents,
on the benzene rings in R1 and R2 of 1 or at the benzene
rings R7 and R8 of 2 gave the corresponding 4-dihydro-1H-
cyclopenta[b]naphthalene derivatives 3g or 3j in higher
yields (Table 2, entries 6 and 9). A similar result was ob-
tained by using unsymmetrical VDCP 1h (R1 =p-ClC6H4,
R2 =C6H5) as the substrate (Table 2, entry 7). In the case of
aliphatic VDCP substrate 1i (R1 =R2 =Me), the correspond-
ing product 3l was obtained in 30% yield (Table 2,
entry 11). As for VDCP 1j in which R3 and R4 are not iden-
tical, two stereoisomeric mixtures were obtained in a ratio
of 1:1 (Table 2, entry 12). Product structures were deter-
mined from 1H and 13C NMR spectroscopic data, HRMS,
and microanalysis. Furthermore, the X-ray crystal structure
of 3a was determined (Figure 1).[5]
Entry[a]
Lewis acid
Yb(OTf)3
Sc(OTf)3
BF3. OEt2
Solvent
T [oC]Yield of
4a [%][b]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
G
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
CH2Cl2
THF
MeCN
toluene
EtOH
hexane
DCE
DCE
DCE
DCE
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
RT
60
40
40
83
87
85
68
81
82
68
69
72
83
NR
47
40
G
Sn
Zr
U
TfOH
La(OTf)3
Nd(OTf)3
Gd(OTf)3
(OTf)3
(OTf)3
(OTf)3
(OTf)3
(OTf)3
(OTf)3
(OTf)3
(OTf)3
(OTf)3
(OTf)3
E
N
G
Sc
Sc
Sc
Sc
Sc
Sc
Sc
Sc
Sc
Sc
C
28
51
trace
86
93[c]
68[d]
Lewis acid catalyzed reactions of VDCPs 1 containing four
methyl groups on the cyclopropane with 1,1,3-triarylprop-2-
[a]All reactions were carried out by using 1k (0.2 mmol), 2b
(0.24 mmol), and catalyst (10 mol%) in various solvents (2.0 mL). [b]Iso-
lated yields. [c] 2b (0.3 mmol) was used. [d] 2a was used.
yn-1-ols ortheirmethyl ethesr 2
: Interestingly, by using
VDCPs 1k–r with four methyl groups on the cyclopropane
Chem. Eur. J. 2008, 14, 8725 – 8731
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8727

M. Shi and L.-F. Yao
(1.5 equiv) in DCE at 408C by using Sc(OTf)3 (10 mol%) as
A
a Lewis acid. Subsequently, we also examined the generality
of this reaction under these optimized conditions, and the
results of these experiments are summarized in Table 4. As
for the reaction of 1k with 2g and 2i, in which R7 and R8 or
R9 are electron-rich aromatic groups, the corresponding
1,2,3,8-tetrahydrocyclopenta[a]indene derivatives 4c and 4e
were obtained in somewhat lower yields (40 and 55%)
(Table 4, entries 3 and 5). In other cases, the corresponding
1,2,3,8-tetrahydrocyclopenta[a]indene derivatives 4 were ob-
tained in 66–92% yields (Table 4, entries 1–9). As for the
substrates 1p–r containing substituents at the meta- and/or
ortho-position of the benzene ring, the corresponding prod-
ucts 4j–l were obtained in 70, 75, and 25% yields, respec-
tively, suggesting that the sterically encumbered VDCP did
not facilitate the formation of 4 (Table 4, entries 10–12). In
the reaction of 1k with 2j, in which R7 and R8 are not iden-
tical, the corresponding product 4m was formed as E- and
Z-isomeric mixtures (Table 4, entry 13). The product 4n was
formed in 60% yield by using 1,1-diphenyl-prop-2-yn-1-ol
2k as a substrate (Table 4, entry 14). The crystal structure of
4d was determined by X-ray diffraction (Figure 2).[5]
Figure 1. ORTEP drawing of 3a.
be carried out at 408C (Table 3, entries 16 and 17). More-
over, 4a could be obtained in 93% yield by using 1.5 equiv
of 2b under the standard conditions (Table 3, entry 18). By
using 2a as a reactant, 4a was formed in 68% yield under
otherwise identical conditions (Table 3, entry 19). Therefore,
we found that the best reaction conditions for the formation
of 4 were to carry out the reactions of VDCPs 1k–r with 2b
It should be noted that in the reactions of VDCP 1a with
1,1-diphenyl-non-2-yn-1-ol 2l and VDCP 1k with 2-methyl-
4-phenyl-but-3-yn-2-ol 2m under these optimized conditions,
complex product mixtures were formed, respectively, sug-
gesting that R7, R8, and R9 in 2 should be aromatic groups
(Scheme 4).
Table 4. Sc(OTf)3-catalyzed reactions of VCPs 1k–r with 3-methoxy-1,3,3-triarylprop-1-yne.
A
Entry
1
R1
R2
2
R9
R7
R8
Yield of 4 [%][a]
1
2
3
4
5
6
7
8
9
10
11
12
13
1k
1k
1k
1k
1k
1l
1m
1n
1o
1p
1q
1r
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
2b
2 f
2g
2h
2i
2b
2b
2b
2b
2b
2b
2b
2j
C6H5
C6H5
C6H5
C6H5
p-MeOC6H4
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
4a, 93
4b, 79
4c, 40
4d, 67
4e, 55
4 f, 74
4g, 82
4h, 66
4i, 92
4j, 70
p-ClC6H4
p-MeC6H4
p-FC6H4
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
p-ClC6H4
p-MeC6H4
p-FC6H4
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
p-FC6H4
p-MeC6H4
p-ClC6H4
p-MeC6H4
m,p-Cl2C6H3
m,p-(CH3)2C6H3
p-ClC6H4
C6H5
p-FC6H4
p-MeC6H4
p-ClC6H4
C6H4
C6H5
C6H5
4k, 75
4l, 25
o-ClC6H4
C6H5
C6H5
C6H5
C6H5
p-ClC6H4
1k
4m, 95 (40:60)[b]
14
1k
[a]Isolated yields. [b]Ratio of E/Z or Z/E 40:60.
8728
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Chem. Eur. J. 2008, 14, 8725 – 8731

Lewis Acid Catalyzed Reactions of Diarylvinylidenecyclopropanes
FULL PAPER
Exploration of the reaction mechanism: A plausible mecha-
nism based on a Meyer–Schuster rearrangement is outlined
in Scheme 5.[6] In the presence of a Lewis acid, an intermedi-
ate propargylic cation A is produced from 1,1,3-triarylprop-
2-yn-1-ol or its methyl ether 2. Nucleophilic attack of the
central carbon in 1 on intermediate A, along with allylic re-
arrangement affords cationic intermediate B.[7] Cyclization
of intermediate B produces cationic intermediates C and D
via an allylic rearrangement.[8] When R3 =R4 =R5 =R6 =Me,
a Friedel–Crafts reaction with the adjacent aromatic group
takes place to afford 1,2,3,8-tetrahydrocyclopenta[a]indene
derivative 4. When R3 and R4 =aromatic groups, a Friedel–
Crafts reaction with R3 or R4 takes place, presumably due to
steric effects, to afford 4-dihydro-1H-cyclopenta[b]naphtha-
lene derivative 3. The formation of a stable cationic inter-
mediate A is the key step in this reaction because when R7,
R8 or R9 are aliphatic groups, complex mixtures of products
are formed (Scheme 4).
Moreover, we found that, as for the reaction of 1k with
2n, which contains two p-methoxyphenyl groups, a novel
functionalized methylenecyclobutene derivative 5a was
formed in 50% yield instead of the 1,2,3,8-tetrahydrocyclo-
penta[a]indene derivative (Scheme 6). The structure of 5a
Figure 2. ORTEP drawing of 4d.
1
was determined by H and 13C NMR spectroscopic data and
from the DEPT spectrum (see the Supporting Information).
This might be because the intermediate formed, cation E,
produces allyl cationic intermediate F, which can be stabi-
lized by two electron-rich aromatic groups, through an intra-
molecular proton transfer. Subsequent cyclization and de-
protonation afford methylenecyclobutene derivative 5a
(Scheme 6).
Because this functionalized methylenecyclobutene deriva-
tive is quite interesting, we next examined the generality of
this reaction. The results are
Scheme 4. Lewis acid catalyzed reaction of VDCP 1a with 1,1-diphenyl-
non-2-yn-1-ol 2l and VDCP 1k with 2-methyl-4-phenyl-but-3-yn-2-ol 2m.
shown in Table 5. As can be
seen from Table 5, the corre-
sponding functionalized meth-
ylenecyclobutene derivatives
5b–f were obtained in moder-
ate to high yields for a variety
of symmetrical or unsymmetri-
cal VDCPs 1l–p (Table 5, en-
tries 1–5). A sterically hindered
unsymmetrical VDCP 1p pro-
duced the corresponding func-
tionalized methylenecyclobu-
tene derivative 5 f in 50%
yield (Table 5, entry 5).
Conclusion
We have found an interesting
Lewis acid catalyzed intermo-
lecular reaction procedure, in
which VDCPs
1 react with
Scheme 5. Plausible reaction mechanism.
1,1,3-triarylprop-2-yn-1-ols or
Chem. Eur. J. 2008, 14, 8725 – 8731
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www.chemeurj.org
8729

M. Shi and L.-F. Yao
Experimental Section
General methods: Melting points are
uncorrected. 1H and 13C NMR spectra
were recorded at 300 and 75 MHz, re-
spectively. Mass spectra were recorded
by EI, ESI, or Maldi methods, and
HRMS measurements were made on a
Finnegan MA+ mass spectrometer.
Organic solvents were dried by stan-
dard methods when necessary. Satis-
factory CHN microanalyses were ob-
tained with a Carlo–Erba 1106 ana-
lyzer. The commercially obtained re-
agents were used directly without fur-
ther purification. All reactions were
monitored by TLC with Huanghai
GF254 silica-gel-coated plates. Flash
column chromatography was carried
out by using 300–400 mesh silica gel at
increased pressure.
General procedure for Lewis acid cat-
alyzed reactions of arylvinylidenecy-
clopropanes with 1,1,3-triarylprop-2-
yn-1-ols ortheirmethyl ethers : Arylvi-
Scheme 6. Sc(OTf)3-catalyzed reaction of 1k with 2n.
A
nylidenecyclopropane
1,1,3-triarylprop-2-yn-1-ols or their
methyl ethers 2 (0.4 mmol) and Zr(OTf)4 or Sc(OTf)3 (10 mol%) were
1
(0.2 mmol),
N
ACHTREUNG
Table 5. Sc(OTf)3-catalyzed reaction of VDCPs 1l–1p with 2n.
N
added into a Schlenk tube under an argon atmosphere. The reaction mix-
ture was stirred at À208C for 6 h in DCE, then the solvent was removed
under reduced pressure and the residue was purified by flash column
chromatography.
Compound 3a: A yellow solid, m.p. 141–1438C; 1H NMR (300 MHz,
CDCl3, Me4Si): d=3.48 (s, 2H, CH2), 6.02 (d, J=7.5 Hz, 2H, Ar), 6.34 (t,
J=7.5 Hz, 2H, Ar), 6.51–6.73 (m, 6H, Ar), 6.89–6.90 (m, 3H, Ar), 7.04–
7.21 (m, 16H, Ar), 7.26 (d, J=7.8 Hz, 2H, Ar), 7.32 (d, J=7.8 Hz, 1H,
Ar), 7.41 ppm (t, J=7.2 Hz, 2H, Ar); 13C NMR (75 MHz, CDCl3, Me4Si):
d=36.7, 57.4, 124.6, 125.0, 125.2, 125.67, 125.72, 125.9, 126.28, 126.31,
126.8, 127.1, 127.3, 127.6, 128.2, 128.7, 129.0, 129.7, 129.8, 130.07, 130.12,
130.5, 133.8, 134.9, 136.5, 138.7, 139.1, 141.2, 141.9, 144.63, 144.66, 146.0,
Entry
R1
R2
1
Yield of 5 [%][a]
1
2
3
4
5
p-FC6H4
p-FC6H4
p-MeC6H4
p-ClC6H4
C6H5
1l
5b, 86
5c, 84
5d, 96
5e, 98
5 f, 50
p-MeC6H4
p-ClC6H4
p-MeC6H4
m,p-Cl2C6H3
1m
1n
1o
1p
149.3, 152.0 ppm; IR(CH2Cl2): n˜ =3055, 3023, 1597, 1489, 1441, 1265,
G
C6H5
1074, 1030, 1003, 912, 771, 740, 697, 669, 649, 627, 619, 572 cmÀ1; MS
[a]Isolated yields.
(MALDI): m/z (%): 636 [M+]; elemental analysis calcd (%) for
C50H36·0.75CH3(CH2)4CH3: C 93.22, H 6.68, found: C 93.55, H 6.54.
A
Compound 4a: A yellow solid, m.p. 203–2058C; 1H NMR (300 MHz,
CDCl3, Me4Si): d=1.49 (s, 3H, CH3), 1.51 (s, 6H, CH3), 1.70 (s, 3H,
CH3), 5.45 (d, J=7.2 Hz, 1H, Ar), 6.57 (t, J=7.8 Hz, 1H, Ar), 6.80 (t,
J=7.8 Hz, 1H, Ar), 7.07–7.10 (m, 5H, Ar), 7.19–7.47 (m, 12H, Ar),
7.51 ppm (d, J=7.2 Hz, 4H, Ar); 13C NMR (75 MHz, CDCl3, Me4Si): d=
23.0, 26.8, 27.0, 55.4, 63.5, 122.7, 123.9, 125.4, 125.5, 125.8, 126.4, 126.6,
126.7, 127.5, 127.8, 128.1, 129.0, 131.0, 131.6, 133.3, 136.5, 141.7, 142.2,
143.7, 146.0, 146.8, 149.5, 159.7, 163.9 ppm; IR (CH2Cl2): n˜ =3057, 2911,
2840, 1597, 1490, 1440, 1361, 1265, 1077, 1035, 763, 740, 700, 623, 558,
551, 535, 527, 513, 506 cmÀ1; MS m/z (%): 540 (100) [M+], 541 (47), 44
(17), 167 (13), 165 (11), 542 (11), 43 (9), 91 (9); HRMS (EI): m/z: calcd
for C42H36: 529.2817; found: 529.2816.
their methyl ethers 2 to provide 4-dihydro-1H-cyclopen-
ta[b]naphthalene derivatives 3 and 1,2,3,8-tetrahydrocyclo-
penta[a]indene derivatives 4 in good to high yields. A plausi-
ble reaction mechanism has been proposed that is based on
a
cascade Meyer–Schuster rearrangement and Friedel–
Crafts reaction pathway. On the basis of this synthetic proto-
col, a series of novel functionalized naphthalene and indene
derivatives were obtained selectively depending on the sub-
stituents on the cyclopropane, by using easily available re-
agents under mild conditions and in moderate to good
yields. Moreover, novel functionalized methylenecyclobu-
tene derivatives 5 could also be obtained in moderate to
good yields when strongly electron-donating methoxy
groups were introduced into the benzene rings of 2 under
similar conditions. Further studies regarding the mechanistic
details and scope of this process are in progress.
1
Compound 5a, A yellow oil; H NMR (300 MHz, CDCl3, Me4Si): d=0.88
(s, 3H, CH3), 1.49 (s, 3H, CH3), 1.54 (s, 3H, CH3), 3.65 (s, 3H, OCH3),
3.66 (s, 3H, OCH3), 4.52 (s, 1H,=CH), 4.71 (s, 1H,=CH), 6.42 (d, J=
8.7 Hz, 2H, Ar), 6.47 (d, J=8.7 Hz, 2H, Ar), 6.66 (d, J=8.7 Hz, 2H, Ar),
6.90–7.03 (m, 7H, Ar), 7.13–7.24 (m, 6H, Ar), 7.36–7.39 ppm (m, 4H,
Ar); 13C NMR (75 MHz, CDCl3, Me4Si): d=20.8, 21.0, 23.3, 55.0, 55.2,
68.7, 112.56, 112.61, 115.3, 125.7, 126.3, 126.4, 127.2, 129.0, 130.1, 131.3,
131.6, 133.5, 133.8, 133.9, 134.0, 141.8, 143.5, 144.2, 146.9, 155.8, 157.7,
158.2 ppm; IR (CH2Cl2): n˜ =3075, 3062, 3032, 2996, 2965, 2947, 2933,
2905, 2837, 2059, 1957, 1886, 1809, 1659, 1638, 1601, 1573, 1516, 1506,
1494, 1456, 1444, 1433, 1409, 1379, 1369, 1330, 1292, 1269, 1244, 1206,
1185, 1170, 1159, 1146, 1111, 1085, 1072, 1049, 1045, 1038, 1003, 989, 984,
8730
www.chemeurj.org
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2008, 14, 8725 – 8731

Lewis Acid Catalyzed Reactions of Diarylvinylidenecyclopropanes
FULL PAPER
974, 958, 941, 925, 909, 897, 885, 866, 849, 843, 825, 801, 787, 777, 766,
758, 746, 740, 729, 715, 701, 692, 683, 668, 658, 642, 631, 614, 600, 593,
580, 575, 569, 549, 540, 535, 526, 507 cmÀ1; MS (MALDI): m/z: 612 [M+];
HRMS (MALDI): m/z: calcd for C44H40O2Na+: 623.2920 [M+Na]+;
found: 623.2920.
[4]a) L.-F. Yao, M. Shi, Org. Lett. 2007, 9, 5187–5190; b) H. Mayr, E.
Bäuml, Tetrahedron Lett. 1984, 25, 1127–1130.
[5]Crystallographic data for 3a: Empirical Formula: C107H81; Formula
Weight: 1372.72; Crystal Color, Habit: colorless, prismatic; Crystal
System: Triclinic; Lattice Type: Primitive; Lattice Parameters: a=
14.5403(17 Š, b=14.9680(18 Š, c=20.922(3) Š, a=103.976(3)o, b=
103.541(2)o, g=105.537(3)o, V=4033.9(8) Š3; Space group: P1; Z=2;
1calc =1.130 gcmÀ3; F000 =1452; Diffractometer: Rigaku AFC7R; Re-
siduals: R; Rw: 0.0778, 0.1998. Crystallographic data for 4d: Empiri-
cal Formula: C42H34F2; Formula Weight: 576.69; Crystal Color, Habit:
colorless, prismatic; Crystal System: Triclinic; Lattice Type: Primi-
tive; Lattice Parameters: a=11.3929(15 Š, b=15.0062(19 Š,
c=29.245(4) Š, a=98.661(3)o, b=100.657(3)o, g=92.025(3)o, V=
4847.3(11 Š3; Space group: P1; Z=6; 1calc =1.185 gcmÀ3; F000 =1824;
Diffractometer: Rigaku AFC7R; Residuals: R; Rw: 0.0556, 0.0904.
CCDC 646896 (3a) 651602 (4d) and contain the supplementary crys-
tallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[6]a) S. Swaminathan, K. V. Narayanan, Chem. Rev. 1971, 71, 429–438;
b) M. Edens, D. Boerner, C. R. Chase, D. Nass, M. D. Schiavelli, J.
Org. Chem. 1977, 42, 3403–3408.
[7]a) D. Regas, M. M. Afonso, M. L. Rodriguez, J. A. Palenzuela, J. Org.
Chem. 2003, 68, 7845–7852; b) B. Xu, M. Shi, Synlett 2003, 1639–
1642; c) Y. Hayashi, T. Shibata, K. Narasaka, Chem. Lett. 1990, 1693–
1696.
Acknowledgements
We thank the Shanghai Municipal Committee of Science and Technology
(04 JC14083, 06XD14005), Chinese Academy of Sciences (KGCX2–210–
01), and the National Natural Science Foundation of China for financial
support (20472096, 203900502, 20672127, and 20732008).
[1]For a recent review, see: a) H. Maeda, K. Mizuno, J. Synth. Org.
Chem. Japan 2004, 62, 1014–1025; for the synthesis of VDCPs, see:
b) K. Isagawa, K. Mizuno, H. Sugita, Y. Otsuji, J. Chem. Soc. Perkin
Trans. 1 1991, 2283–2285, and references therein. c) J. R. Al-Dulayy-
mi, M. S. Baird, J. Chem. Soc. Perkin Trans. 1 1994, 1547–1548.
[2]For selected recent articles about VDCPs, see: a) H. Maeda, T. Hirai,
A. Sugimoto, K. Mizuno, J. Org. Chem. 2003, 68, 7700–7706; b) D. J.
Pasto, J. E. Brophy, J. Org. Chem. 1991, 56, 4554–4556; c) H. Sugita,
K. Mizuno, T. Saito, K. Isagawa, Y. Otsuji, Tetrahedron Lett. 1992, 33,
2539–2542; d) K. Mizuno, H. Sugita, T. Kamada, Y. Otsuji, Chem.
Lett. 1994, 449–452, and references therein.
[3]For recent contributions from our group on Lewis acid catalyzed
transformations, see: a) G.-C. Xu, L.-P. Liu, J.-M. Lu, M. Shi, J. Am.
Chem. Soc. 2005, 127, 14552–14553; b) G.-C. Xu, M. Ma, L.-P. Liu,
M. Shi, Synlett 2005, 1869–1872; c) Y.-P. Zhang, J.-M. Lu, G.-C. Xu,
M. Shi, J. Org. Chem. 2007, 72, 509–516; d) J.-M. Lu, M. Shi, Org.
Lett. 2006, 8, 5317–5320; e) J.-M. Lu, M. Shi, Org. Lett. 2007, 9,
1805–1808.
[8]Selected papers on such allylic rearrangement: a) H.-U. Siehl, F.-P.
Kaufmann, Y. Apeloig, V. Braude, D. Danovich, A. Berndt, N. Sta-
matis, Angew. Chem. 1991, 103, 1546–1549; Angew. Chem. Int. Ed.
Engl. 1991, 30, 1479–1482; b) C. U. Pittman, J. Chem. Soc. D. 1969,
122–123.
Received: March 8, 2008
Published online: August 7, 2008
Chem. Eur. J. 2008, 14, 8725 – 8731
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8731