Gold-catalyzed skeletal rearrangement of 1-[2-(1 H-isochromen-3-yl)aryl] ethanones with alcohols

Article abstract of DOI:10.1055/s-0031-1291152

A novel gold-catalyzed skeletal rearrangement of 1-[2-(1H-isochromen-3-yl) aryl]ethanones with alcohols to construct a five-membered carbocycle ring onto aromatic systems has been developed. This method serves as the first example of synthesizing inden-1-ones by a gold-catalyzed skeletal rearrangement strategy. Georg Thieme Verlag Stuttgart ? New York.

Full text of DOI:10.1055/s-0031-1291152

PAPER
▌2049
pGapoerld-Catalyzed Skeletal Rearrangement of 1-[2-(1H-Isochromen-3-yl)aryl]-
ethanones with Alcohols
Gold-Catalyzed Synthesis of Inden-1-ones
Wen-Ting Wei,a,b Peng Xie,a,b Jia-Dong Xia,a,b Ye-Xiang Xie,*a Ren-Jie Song,a Jian-Nan Xiang,a Jin-Heng Li*a
a
College of Chemistry and Chemical Engineering, and State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University,
Changsha 410082, P. R. of China
Fax +86(731)88872101; E-mail: jhli@hnu.edu.cn; E-mail: xieyexiang520@126.com
b
Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education), Hunan Normal University,
Changsha 410081, P. R. of China
Received: 07.03.2012; Accepted after revision: 19.04.2012
tions have attracted significant interest because of their
Abstract: A novel gold-catalyzed skeletal rearrangement of 1-[2-
synthetic utility and concept: these transformations are
(1H-isochromen-3-yl)aryl]ethanones with alcohols to construct a
highly efficient and atom-economical and provide oppor-
five-membered carbocycle ring onto aromatic systems has been de-
tunities to rapidly construct complex molecules and dis-
cover new reactions.8,9 Interestingly, this strategy was
applied to construct various carbocycles,8 including in-
dene derivatives.9 To the best of our knowledge, however,
skeletal rearrangement of 1-[2-(1H-isochromen-3-yl)ar-
yl]ethanones with alcohols for the synthesis of inden-1-
ones has not been reported.
veloped. This method serves as the first example of synthesizing in-
den-1-ones by a gold-catalyzed skeletal rearrangement strategy.
Key words: gold, skeletal rearrangement, 1-[2-(1H-isochromen-3-
yl)aryl]ethanones, alcohols, inden-1-ones
Inden-1-one and its derivatives are commonly found in
natural compounds, pharmaceuticals, and functional
materials, as well as being versatile synthetic blocks and
catalysts in organic synthesis.1 Most often, the intramo-
lecular Friedel–Crafts acylation of 3-arylpropanoic acids
and their derivatives is the most direct method for their
construction.2,3 However, the classical Friedel–Crafts
transformation generally require the use of at least an
equivalent amount of either a Lewis or Brønsted acid.3
Thus, it is desirable to develop a catalytic system for these
purposes. Recently, many catalytic methods have been
disclosed,3–7 including the Friedel–Crafts reaction,3
Nazarov cyclization,4 transition-metal-catalyzed annula-
tion,5 and ring-closing metathesis.6 Here, we report a nov-
el route to prepare polysubstituted inden-1-ones by gold-
catalyzed skeletal rearrangement of 1-[2-(1H-isochro-
men-3-yl)aryl]ethanones with alcohols (Scheme 1).
Our study began with the reaction of 1-[2-(4-methyl-1H-
isochromen-3-yl)phenyl]ethanone (1a) with 5 mol%
AuBr3 in THF at 80 °C; however, no reaction was ob-
served (Table 1, entry 1). Gratifyingly, an unexpected
skeletal rearrangement reaction took place in the presence
of MeOH (2a): the desired rearrangement product, 2-[2-
(methoxymethyl)phenyl]-2-methyl-3-methylene-2,3-di-
hydro-1H-inden-1-one (3), was obtained in 10% yield at a
loading of 10 equivalents of MeOH (entry 2).10 In light of
the results, MeOH was employed as the solvent, and the
yield of product 3 was enhanced sharply to 78% (entry 3).
The amount of AuBr3 was subsequently investigated (en-
tries 3–5): 10 mol% AuBr3 gave identical results to those
of 5 mol% AuBr3 (entry 4), whereas the yield was lowered
to 59% when 2 mol% AuBr3 was used (entry 5). Notably,
the reaction cannot take place without gold catalysts (en-
try 6). Screening revealed that gold catalysts, such as
AuCl3, HAuCl4, AuCl, or AuI, have reactivity for the re-
action, but they were less effective than AuBr3 (entries 7–
10). Among the reaction temperature examined, it turned
out the reaction at 80 °C gave the best results (entries 3,
11, and 12). However, other metal catalysts, PtBr2 and
PdBr2, had no effect on the reaction (entries 13 and 14).
O
R4
R3
O
O
R3
R2
R4OH 2
AuBr3, 80 °C, 12 h
R2
R1
R1
O
1
Scheme 1 Gold-catalyzed skeletal rearrangement
With the optimal reaction conditions in hand, the scope of
both 1-[2-(1H-isochromen-3-yl)aryl]ethanones 1 and al-
cohols 2 was explored (Table 2).10 Initially, a number of
alcohols 2b–f were investigated for the reaction with 1-[2-
(4-methyl-1H-isochromen-3-yl)phenyl]ethanone (1a) and
AuBr3 (Table 2, entries 1–5). The results disclosed that
both primary and secondary alcohols were suitable for the
reaction (entries 1–4), but tertiary alcohol (t-BuOH) could
not furnish the desired product 8 (entry 5). It was found
that BnOH (2g) was also less reactive for the reaction (en-
try 6). Subsequently, a variety of 1-[2-(1H-isochromen-3-
Gold is one of the most important transition metal cata-
lysts in organic synthesis, and has been widely used in or-
ganic synthesis for constructing numerous chemical
bonds.8,9 Particularly, gold-catalyzed rearrangement reac-
SYNTHESIS 2012, 44, 2049–2057
Advanced online publication: 01.06.2012
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
DOI: 10.1055/s-0031-1291152; Art ID: SS-2012-H0240-OP
© Georg Thieme Verlag Stuttgart · New York

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W.-T. Wei et al.
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ing
2-[2-(methoxymethyl)phenyl]-3-methylene-2,3-
Table 1 Screening Conditions for Gold-Catalyzed Skeletal Rear-
rangementa
dihydro-1H-inden-1-one (10) in 41% yield (entry 7). In-
terestingly, substrates 1c–l with a methyl group on the 4-
position of the 1H-isochromene moiety were also success-
ful in the rearrangement reaction (entries 8–17). More-
over, screening revealed that several functional groups,
including Me, MeO, OCH2O, F, Cl, and NO2 on the aro-
matic ring of substrates 1 were tolerated well under the
optimal conditions. For example, substrates with three Me
groups on different aryl rings smoothly underwent the re-
action with MeOH and AuBr3, providing the correspond-
ing products 11 and 12 in good yields (entries 8 and 9).
MeO-substituted substrates were also consistent with the
optimal conditions: Substrate with two MeO group
formed the target product 14 in 86% yield (entry 11), and
four MeO-substituted substrate still gave a moderate yield
(entry 12). Gratifyingly, a heterocycle and a protected di-
ol, which were introduced into this system, also make this
methodology more useful for the preparation of pharma-
ceuticals and natural products (entry 13). Importantly,
substituents, Cl and F, were found to be compatible with
the optimal conditions, thereby facilitating additional
modifications at the halogenated positions (entries 14–
16). Interestingly, substrate 1l with two electron-with-
drawing NO2 groups could also react with MeOH and
AuBr3 to give the desired product in moderate yield (entry
17).
O
O
Me
O
[M]
+
MeOH
2a
O
1a
3
Entry [M] (mol%)
Solvent
THF
Temp (°C) Yield (%)b
1
2c
3
4
5
6
7
8
9
AuBr3 (5)
AuBr3 (5)
AuBr3 (5)
AuBr3 (10)
AuBr3 (2)
–
80
80
80
80
80
80
80
80
80
80
100
60
80
80
0
10
78
79
59
0
MeOH–THF
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
AuCl3 (5)
HAuCl4 (5)
AuCl (5)
AuI (5)
20
41
30
33
78
40
trace
trace
10
11
12
13
14
AuBr3 (5)
AuBr3 (5)
PtBr2 (5)
PdBr2 (5)
As shown in Scheme 2, the reactions some other iso-
chromenes 1 were also investigated in the presence of
AuBr3 and MeOH (2a). The results demonstrated that 2-
(1H-isochromen-3-yl)benzaldehyde (1m) was not a suit-
able substrate for the rearrangement reaction: only <5%
yield of the desired product 21 was observed by GC-MS
analysis (Scheme 2, equation 1). It is noteworthy that a
carbonyl group on the 2-position of the 3-phenyl ring in
1H-isochromenes is the key for the occurrence of the re-
action; no reaction takes place using 3-phenyl-1H-iso-
chromene (1n) (Scheme 2, equation 2).
a Reaction conditions: 1a (0.3 mmol), [M], and solvent (2 mL) for 12
h under argon atmosphere.
b Isolated yield.
c Amount of MeOH added: 10 equiv.
yl)aryl]ethanones 1b–l were treated with MeOH (2a) and
AuBr3 (entries 7–17). The results disclosed that 1-[2-(1H-
isochromen-3-yl)phenyl]ethanone (1b) smoothly under-
went the rearrangement reaction to afford the correspond-
Table 2 Gold-Catalyzed Rearrangement of 1-[2-(1H-Isochromen-3-yl)aryl]ethanones 1 with Alcohols 2a
O
R4
O
O
R3
R2
R4OH 2
AuBr3, 80 °C, 12 h
R3
R2
R1
R1
O
1
Entry
Substrate 1
R4OH 2
Product (Yield, %)b
O
O
Et
O
1
EtOH (2b)
O
1a
4 (60)
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Gold-Catalyzed Synthesis of Inden-1-ones
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Table 2 Gold-Catalyzed Rearrangement of 1-[2-(1H-Isochromen-3-yl)aryl]ethanones 1 with Alcohols 2a (continued)
O
R4
O
O
R3
R2
R4OH 2
AuBr3, 80 °C, 12 h
R3
R2
R1
R1
O
1
Entry
Substrate 1
R4OH 2
Product (Yield, %)b
O
O
n-Pr
O
2
n-PrOH (2c)
O
1a
5 (72)
O
O
i-Pr
O
3
i-PrOH (2d)
O
1a
6 (40)
7 (70)
8 (0)
O
O
n-Bu
O
4
5
6
7
8
n-BuOH (2e)
t-BuOH (2f)
BnOH (2g)
MeOH (2a)
MeOH (2a)
O
1a
O
O
O
O
t-Bu
O
O
O
O
1a
O
Bn
O
1a
9 (12)
O
Me
O
1b
10 (41)
O
O
O
Me
O
11 (87)
1c
© Georg Thieme Verlag Stuttgart · New York
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Table 2 Gold-Catalyzed Rearrangement of 1-[2-(1H-Isochromen-3-yl)aryl]ethanones 1 with Alcohols 2a (continued)
O
R4
O
O
R3
R2
R4OH 2
AuBr3, 80 °C, 12 h
R3
R2
R1
R1
O
1
Entry
Substrate 1
R4OH 2
Product (Yield, %)b
O
O
Me
O
9
MeOH (2a)
O
1d
12 (80)
O
O
O
Me
10
11
12
MeOH (2a)
MeOH (2a)
MeOH (2a)
O
1e
13 (46)
O
O
OMe
Me
OMe
O
MeO
MeO
O
1f
14 (86)
O
OMe
OMe
O
O
Me
OMe
MeO
MeO
MeO
OMe
O
OMe
15 (51)
1g
O
O
O
O
O
Me
O
O
O
13
MeOH (2a)
O
O
O
O
16 (89)
1h
O
F
O
O
Me
F
14
15
MeOH (2a)
MeOH (2a)
F
O
F
17 (75)
1i
O
O
Me
O
F
F
F
F
O
1j
18 (81)
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Gold-Catalyzed Synthesis of Inden-1-ones
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Table 2 Gold-Catalyzed Rearrangement of 1-[2-(1H-Isochromen-3-yl)aryl]ethanones 1 with Alcohols 2a (continued)
O
R4
O
O
R3
R2
R4OH 2
AuBr3, 80 °C, 12 h
R3
R2
R1
R1
O
1
Entry
Substrate 1
R4OH 2
Product (Yield, %)b
O
Cl
O
O
Me
Cl
16
17
MeOH (2a)
Cl
O
Cl
19 (60)
1k
O
NO2
O
O
Me
NO2
MeOH (2a)
O2N
O
NO2
20 (60)
1l
a Reaction conditions: 1 (0.3 mmol), alcohol 2 (2 mL), and AuBr3 (5 mol%) at 80 °C for 12 h under argon atmosphere.
b Isolated yield.
O
Me
CHO
O
AuBr3
MeOH
+
(1)
80 °C, 12 h
2a
O
1m
21 (<5%)
O
AuBr3
>95% of 1n
was recovered
(2)
MeOH
+
80 °C, 12 h
2a
1n
Scheme 2 AuBr3-catalyzed rearrangement reactions of other isochromenes 1m,n with MeOH (2a)
O
O
Me
O
MeOH (2a)
AuBr3, 80 °C, 12 h
O
3
1a
AuBr3
Me
Br-
Br2Au
AuBr3
Me
MeOH
O
O
O
O
O
O
O
HBr
H2O
AuBr2
AuBr3
AuBr2
O
D
A
C
B
Scheme 3 Possible mechanism for the gold-catalyzed skeletal rearrangement
© Georg Thieme Verlag Stuttgart · New York
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W.-T. Wei et al.
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Hz, 1 H), 5.64 (s, 1 H), 5.27 (s, 1 H), 4.90 (d, J = 14.5 Hz, 1 H), 4.70
(d, J = 15.0 Hz, 1 H), 3.35 (s, 3 H), 1.59 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 202.5, 153.1, 140.5, 140.1, 138.7,
132.9, 129.5, 127.6, 127.0, 125.9, 124.8, 123.7, 121.9, 107.5, 105.2,
64.9, 52.6, 50.4, 21.8.
LRMS (EI, 70 eV): m/z (%) = 278 (M+, 4), 231 (100), 202 (40).
HRMS (EI): m/z calcd for C19H18O2 (M+): 278.1307; found:
A possible mechanism as outlined in Scheme 3 is pro-
posed.8,9 Complexation of substrate 1a with AuBr3 yields
intermediate A, in which the C=C bond is activated by the
AuBr3 Lewis acid catalyst. Subsequently, the addition of
the oxygen atom of the carbonyl group to the C=C bond
takes place to offer intermediate B, followed by addition
of methanol to intermediate B to form a six-membered
oxocycle intermediate C.9e Intermediate C undergoes the
oxygen-migration-ring-opening-cyclization sequence to
afford intermediate D. Finally, the desired product 3 is ob-
tained from intermediate D together with the regeneration
of the active gold species.
278.1311.
2-[2-(Ethoxymethyl)phenyl]-2-methyl-3-methylene-2,3-di-
hydro-1H-inden-1-one (4)
Yield: 52.6 mg (60%); colorless oil.
IR (KBr): 2926, 1747 cm–1.
In summary, we have described a novel and general meth- 1H NMR (500 MHz, CDCl3): δ = 7.44–7.41 (m, 3 H), 7.23–7.21 (m,
2 H), 7.12 (s, 1 H), 7.02 (s, 1 H), 6.82 (d, J = 7.5 Hz, 1 H), 5.56 (s,
1 H), 5.15 (s, 1 H), 4.78 (d, J = 14.5 Hz, 1 H), 4.61 (d, J = 14.5 Hz,
1 H), 3.78–3.75 (m, 1 H), 3.33–3.30 (m, 1 H), 1.52 (s, 3 H), 1.05 (t,
J = 7.0 Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 207.3, 153.0, 140.5, 140.0, 138.7,
132.8, 129.5, 127.6, 127.0, 125.9, 124.8, 123.7, 121.9, 107.5, 105.2,
64.9, 52.6, 50.4, 21.8, 14.2.
LRMS (EI, 70 eV): m/z (%) = 292 (M+, 8), 247 (40), 157 (82).
od for the construction of 2,3-dihydro-1H-inden-1-ones
by alcohol-induced gold-catalyzed skeletal rearrange-
ment. Importantly, this rearrangement method provides a
new synthetic utility for gold catalysts. Further study of
the detailed mechanism and applications of this gold-
catalyzed rearrangement transformation in organic syn-
thesis are currently underway in our laboratory.
HRMS (EI): m/z for C20H20O2 (M+): 292.1463; found: 292.1467.
NMR spectroscopy was performed on a Bruker Avance spectrome-
ter operating at 500 MHz (1H NMR) and 125 MHz (13C NMR).
Mass spectrometric analysis was performed using GC-MS tech-
nique (Shimadzu GCMS-QP2010) and ESI-Q-TOF (Bruker Micro-
QTOF-II. All melting points are uncorrected.
2-Methyl-3-methylene-2-[2-(propoxymethyl)phenyl]-2,3-di-
hydro-1H-inden-1-one (5)
Yield: 66.1 mg (72%); colorless oil.
IR (KBr): 2931, 1692 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.44–7.40 (m, 3 H), 7.21–7.20 (m,
2 H), 7.10 (t, J = 7.5 Hz, 1 H), 7.00 (t, J = 7.0 Hz, 1 H), 6.81 (d,
J = 7.5 Hz, 1 H), 5.54 (s, 1 H), 5.17 (s, 1 H), 4.80 (d, J = 14.5 Hz, 1
H), 4.62 (d, J = 14.5 Hz, 1 H), 3.68 (t, J = 7.5 Hz, 1 H), 3.22 (t,
J = 7.5 Hz, 1 H), 1.52 (s, 3 H), 1.46–1.41 (m, 2 H), 0.77 (t, J = 7.5
Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 200.8, 153.4, 140.5, 140.2, 133.1,
129.3, 127.6, 127.0, 126.9, 125.8, 124.7, 123.7, 121.7, 107.1, 105.0,
64.8, 64.0, 52.7, 23.1, 22.0, 10.6.
All starting materials were synthesized according to the literature
procedure.9e The analytical and spectral data for 1a are given below.
1-[2-(4-Methyl-1H-isochromen-3-yl)phenyl]ethanone (1a)
IR (KBr): 2925, 1768 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.58 (d, J = 7.5 Hz, 1 H), 7.49–
7.46 (m, 1 H), 7.44–7.41 (m, 2 H), 7.31 (t, J = 7.5 Hz, 1 H), 7.22–
7.20 (m, 2 H), 7.05 (d, J = 7.5 Hz, 1 H), 5.07 (s, 2 H), 2.52 (s, 3 H),
1.99 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 202.5, 149.6, 141.4, 133.6, 133.5,
131.3, 130.3, 128.8, 128.7, 128.0, 127.5, 126.7, 123.6, 121.0, 109.8,
69.2, 29.4, 13.6.
LRMS (EI, 70 eV): m/z (%) = 306 (M+, 4), 231 (100), 217 (22).
HRMS (EI): m/z calcd for C21H22O2 (M+): 306.1620; found:
306.1624.
LRMS (EI, 70 eV): m/z (%): 265 (M+ + 1, 19), 264 (100), 115 (44).
HRMS (EI): m/z calcd for C18H16O2 (M+): 264.1223; found:
264.1226.
2-[2-(Isopropoxymethyl)phenyl]-2-methyl-3-methylene-2,3-di-
hydro-1H-inden-1-one (6)
Yield: 36.7 mg (40%); colorless oil.
IR (KBr): 2919, 1684 cm–1.
Gold-Catalyzed Skeletal Rearrangement Reaction; General
Procedure
1H NMR (500 MHz, CDCl3): δ = 7.49 (d, J = 7.5 Hz, 1 H), 7.42 (t,
J = 8.5 Hz, 2 H), 7.28 (t, J = 4.5 Hz, 1 H), 7.22 (t, J = 6.0 Hz, 1 H),
7.09 (t, J = 8.5 Hz, 1 H), 6.88 (d, J = 2.5 Hz, 1 H), 6.82 (d, J = 7.5
Hz, 1 H), 5.54 (s, 1H), 5.14 (s, 1 H), 4.84 (d, J = 11.0 Hz, 1 H), 4.62
(d, J = 13.0 Hz, 1 H), 3.28–3.23 (m, 1 H), 1.51 (s, 3 H), 1.49 (d,
J = 7.0 Hz, 3 H), 1.46 (d, J = 6.5 Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 197.2, 153.1, 140.5, 140.1, 138.8,
132.9, 129.5, 127.6, 127.0, 125.9, 124.8, 123.7, 121.9, 107.5, 105.2,
71.5, 64.9, 52.6, 21.8, 21.3, 20.7.
To a Schlenk tube were added 1-[2-(4-methyl-1H-isochromen-3-
yl)phenyl]ethanone 1 (0.3 mmol), AuBr3 (5 mol%), and alcohol 2 (2
mL). Then, the tube was charged with argon and the mixture was
stirred at 80 °C (oil bath temperature) for 12 h until complete con-
sumption of starting material as monitored by TLC (eluent: hexane–
EtOAc, 10:1) and GC-MS analysis. After completion of the reac-
tion, the mixture was cooled to r.t., diluted with EtOAc (10 mL),
and the EtOAc layer was washed with brine (3 × 3 mL). The aque-
ous phase was re-extracted with EtOAc (3 × 5 mL). The combined
organic extracts were dried (Na2SO4) and concentrated under vacu-
um. The resulting residue was purified by silica gel column chroma-
tography (hexane–EtOAc, 5:1) to afford the desired product.
LRMS (EI, 70 eV): m/z (%) = 306 (M+, 16), 247 (28), 231 (100).
HRMS (EI): m/z calcd for C21H22O2 (M+): 306.1620; found:
306.1624.
2-[2-(Methoxymethyl)phenyl]-2-methyl-3-methylene-2,3-di-
hydro-1H-inden-1-one (3)
2-[2-(Butoxymethyl)phenyl]-2-methyl-3-methylene-2,3-di-
hydro-1H-inden-1-one (7)
Yield: 67.2 mg (70%); colorless oil.
IR (KBr): 2925, 1740 cm–1.
Yield: 65.9 mg (79%); colorless oil.
IR (KBr): 2928, 1748 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.52–7.49 (m, 3 H), 7.32–7.28 (m,
2 H), 7.18 (d, J = 7.5 Hz, 1 H), 7.10–7.07 (m, 1 H), 6.88 (d, J = 7.0
Synthesis 2012, 44, 2049–2057
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Gold-Catalyzed Synthesis of Inden-1-ones
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1H NMR (500 MHz, DMSO-d6): δ = 7.57–7.55 (m, 1 H), 7.50–7.48
(m, 2 H), 7.33–7.31 (m, 2 H), 7.17 (s, 1 H), 7.09–7.07 (m, 1 H), 6.93
(d, J = 7.5 Hz, 1 H), 5.70 (s, 1 H), 5.36 (s, 1 H), 4.88 (d, J = 15.0 Hz,
1 H), 4.60 (d, J = 15.0 Hz, 1 H), 3.79 (d, J = 9.0 Hz, 1 H), 3.21 (d,
J = 9.5 Hz, 1 H), 1.48 (s, 3 H), 1.36–1.32 (m, 2 H), 1.24–1.20 (m, 2
H), 0.77 (t, J = 7.0 Hz, 3 H).
13C NMR (125 MHz, DMSO-d6): δ = 202.9, 153.1, 140.6, 140.4,
139.3, 133.2, 130.1, 128.2, 127.5, 127.4, 126.5, 125.3, 124.3, 107.0,
106.2, 64.5, 61.6, 52.7, 31.9, 22.2, 19.4, 14.2.
Hz, 1 H), 4.75 (d, J = 13.5 Hz, 1 H), 3.40 (s, 3 H), 2.29 (s, 3 H), 2.27
(s, 3 H), 2.24 (s, 3 H), 2.20 (s, 3 H), 1.53 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 201.5, 155.4, 153.5, 143.5, 139.1,
137.4, 136.7, 136.1, 136.0, 135.8, 135.5, 134.8, 133.9, 106.9, 103.7,
64.8, 52.5, 50.4, 20.2, 20.1, 20.0, 19.8, 19.6.
LRMS (EI, 70 eV): m/z (%) = 334 (M+, 9), 297 (100), 149 (21).
HRMS (EI): m/z calcd for C23H26O2 (M+): 334.1933; found:
334.1937.
LRMS (EI, 70 eV): m/z (%) = 320 (M+, 1), 246 (6), 40 (100).
HRMS (EI): m/z calcd for C22H24O2 (M+): 320.1776; found:
6-Methoxy-2-[4-methoxy-2-(methoxymethyl)phenyl]-2-methyl-
3-methylene-2,3-dihydro-1H-inden-1-one (14)
Yield: 87.2 mg (86%); yellow oil.
IR (KBr): 2922, 1697 cm–1.
1H NMR (500 MHz, DMSO-d6): δ = 7.46 (d, J = 8.5 Hz, 1 H), 7.37
(d, J = 8.5 Hz, 1 H), 7.02 (d, J = 2.0 Hz, 1 H), 6.93–6.91 (m, 1 H),
6.75–6.73 (m, 1 H), 6.51 (d, J = 2.5 Hz, 1 H), 5.49 (s, 1 H), 5.18 (s,
1 H), 4.84 (d, J = 15.0 Hz, 1 H), 4.61 (d, J = 15.0 Hz, 1 H), 3.80 (s,
3 H), 3.64 (s, 3 H), 3.23 (s, 3 H), 1.41 (s, 3 H).
13C NMR (125 MHz, DMSO-d6): δ = 202.2, 159.7, 157.8, 152.8,
140.4, 134.3, 133.2, 132.4, 128.8, 123.6, 116.9, 114.1, 110.0, 108.5,
107.3, 64.8, 56.1, 55.6, 52.4, 50.4, 22.1.
320.1780.
2-[2-(Methoxymethyl)phenyl]-3-methylene-2,3-dihydro-1H-in-
den-1-one (10)
Yield: 32.5 mg (41%); yellow oil.
IR (KBr): 2927, 1752 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.52–7.49 (m, 3 H), 7.32–7.28 (m,
2 H), 7.19 (t, J = 7.5 Hz, 1 H), 7.10–7.07 (m, 1 H), 6.88 (d, J = 7.0
Hz, 1 H), 5.64 (s, 1 H), 5.27 (s, 1 H), 4.89 (d, J = 14.5 Hz, 1 H), 4.71
(d, J = 15.0 Hz, 1 H), 4.41 (s, 1 H), 3.11 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 202.5, 153.1, 140.5, 140.1, 138.7,
132.9, 129.5, 127.6, 127.0, 125.9, 124.8, 123.7, 121.9, 107.5, 105.2,
59.0, 52.6, 50.4.
LRMS (EI, 70 eV): m/z (%) = 338 (M+, 19), 291 (88), 166 (42).
HRMS (EI): m/z calcd for C21H22O4 (M+): 338.1518; found:
338.1522.
LRMS (EI, 70 eV): m/z (%) = 264 (M+, 27), 246 (100), 176 (11).
HRMS (EI): m/z calcd for C18H16O2 (M+): 264.1150; found:
264.1154.
2-[4,5-Dimethoxy-2-(methoxymethyl)phenyl]-5,6-dimethoxy-2-
methyl-3-methylene-2,3-dihydro-1H-inden-1-one (15)
Yield: 60.9 mg (51%); white solid; mp 99.6–100.7 °C.
IR (KBr): 2928, 1701 cm–1.
2-[2-(Methoxymethyl)-4-methylphenyl]-2,6-dimethyl-3-meth-
ylene-2,3-dihydro-1H-inden-1-one (11)
1H NMR (500 MHz, CDCl3): δ = 7.21 (s, 1 H), 7.10 (s, 1 H), 7.09
(s, 1 H), 6.90 (s, 1 H), 5.51 (s, 1 H), 5.23 (s, 1 H), 5.01 (d, J = 6.5
Hz, 1 H), 4.78 (d, J = 6.5 Hz, 1 H), 3.98 (s, 3 H), 3.91 (s, 3 H), 3.90
(s, 3 H), 3.81 (s, 3 H), 2.88 (s, 3 H), 1.60 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 204.6, 155.7, 152.2, 151.6, 148.1,
147.6, 142.0, 130.6, 129.6, 127.4, 112.6, 112.2, 105.5, 104.6, 102.2,
60.4, 57.6, 56.8, 56.3, 56.1, 55.9, 50.9, 22.7.
Yield: 79.9 mg (87%); yellow oil.
IR (KBr): 2931, 1745 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.45 (d, J = 8.0 Hz, 1 H), 7.31–
7.29 (m, 1 H), 7.23 (s, 1 H), 7.03 (s, 1 H), 6.95–6.88 (m, 2 H), 5.47
(s, 1 H), 5.10 (s, 1 H), 4.75 (d, J = 14.5 Hz, 1 H), 4.60 (d, J = 11.0
Hz, 1 H), 3.27 (s, 3 H), 2.30 (s, 3 H), 2.16 (s, 3 H), 1.48 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 203.9, 153.2, 142.8, 139.4, 137.6,
135.5, 132.7, 130.5, 127.8, 126.8, 125.1, 124.1, 121.6, 107.6, 104.0,
64.9, 52.5, 50.5, 21.8, 21.6, 20.9.
LRMS (EI, 70 eV): m/z (%) = 398 (M+, 12), 217 (100), 40 (72).
HRMS (EI): m/z calcd for C23H26O6 (M+): 398.1729; found:
398.1733.
LRMS (EI, 70 eV): m/z (%) = 306 (M+, 22), 171 (100), 40 (82).
HRMS (EI): m/z for C21H22O2 (M+): 306.1620; found: 306.1624.
6-[4-(Methoxymethyl)benzo[d][1,3]dioxol-5-yl]-6-methyl-7-
methylene-6,7-dihydro-5H-indeno[5,6-d][1,3]dioxol-5-one (16)
Yield: 97.7 mg (89%); white solid; mp 102.5–103.4 °C.
IR (KBr): 2930, 1752 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.12 (s, 1 H), 7.07 (s, 1 H), 7.06
(s, 1 H), 6.85 (s, 1 H), 6.07 (d, J = 2.5 Hz, 2 H), 5.92 (d, J = 1.5 Hz,
1 H), 5.89 (d, J = 1.0 Hz, 1 H), 5.46 (s, 1 H), 4.79 (s, 1 H), 3.79 (d,
J = 13.0 Hz, 1 H), 3.73 (d, J = 13.0 Hz, 1 H), 2.88 (s, 3 H), 1.54 (s,
3 H).
13C NMR (125 MHz, CDCl3): δ = 203.6, 154.6, 151.7, 150.2, 146.9,
146.8, 144.3, 131.8, 131.0, 129.3, 114.7, 109.2, 106.0, 102.7, 102.5,
101.2, 100.7, 71.7, 57.5, 57.2, 26.6.
2-[2-(Methoxymethyl)-5-methylphenyl]-2,5-dimethyl-3-meth-
ylene-2,3-dihydro-1H-inden-1-one (12)
Yield: 73.4 mg (80%); colorless oil.
IR (KBr): 2930, 1744 cm–1.
1H NMR (500 MHz, DMSO-d6): δ = 7.40–7.35 (m, 2 H), 7.27–7.22
(m, 2 H), 7.12 (d, J = 8.0 Hz, 1 H), 6.87 (d, J = 8.0 Hz, 1 H), 5.64
(s, 1 H), 5.34 (s, 1 H), 4.84 (d, J = 15.0 Hz, 1 H), 4.55 (d, J = 16.0
Hz, 1 H), 3.19 (s, 3 H), 2.27 (s, 3 H), 2.21 (s, 3 H), 1.43 (s, 3 H).
13C NMR (125 MHz, DMSO-d6): δ = 200.4, 153.1, 140.9, 140.4,
139.8, 136.4, 130.1, 129.0, 127.9, 127.4, 125.3, 124.2, 122.9, 107.3,
106.0, 64.6, 52.8, 50.2, 22.1, 21.6, 21.5.
LRMS (EI, 70 eV): m/z (%) = 366 (M+, 7), 335 (42), 40 (52).
HRMS (EI): m/z calcd for C21H18O6 (M+): 366.1103; found:
LRMS (EI, 70 eV): m/z (%) = 306 (M+, 2), 273 (14), 40 (100).
HRMS (EI): m/z calcd for C21H22O2 (M+): 306.1620; found:
366.1107.
306.1624.
6-Fluoro-2-[4-fluoro-2-(methoxymethyl)phenyl]-2-methyl-3-
methylene-2,3-dihydro-1H-inden-1-one (17)
Yield: 70.7 mg (75%); light yellow oil.
IR (KBr): 2920, 1715 cm–1.
1H NMR (500 MHz, DMSO-d6): δ = 7.63–7.61 (m, 1 H), 7.53–7.50
(m, 1 H), 7.40–7.38 (m, 1 H), 7.22–7.18 (m, 1 H), 7.03–7.00 (m, 1
2-[2-(Methoxymethyl)-4,5-dimethylphenyl]-2,5,6-trimethyl-3-
methylene-2,3-dihydro-1H-inden-1-one (13)
Yield: 46.1 mg (46%); colorless oil.
IR (KBr): 2945, 1746 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.50 (s, 1 H), 7.39 (s, 1 H), 7.07
(s, 1 H), 7.00 (s, 1 H), 5.42 (s, 1 H), 5.17 (s, 1 H), 5.05 (d, J = 11.5
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2049–2057

2056
W.-T. Wei et al.
PAPER
H), 6.84–6.82 (m, 1 H), 5.67 (s, 1 H), 5.35 (s, 1 H), 4.89 (d, J = 15.5
Hz, 1 H), 4.61 (d, J = 15.5 Hz, 1 H), 3.24 (s, 3 H), 1.44 (s, 3 H).
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis.SnoIufproi
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13C NMR (125 MHz, DMSO-d6): δ = 202.3, 151.8, 141.0, 136.7,
136.1, 135.5 (d, J = 7.0 Hz, 1 C), 129.9 (d, J = 8.0 Hz, 1 C), 124.5
(d, J = 9.0 Hz, 1 C), 117.8 (d, J = 23.0 Hz, 1 C), 114.7 (d, J = 21.0
Hz, 1 C), 112.5 (d, J = 23.0 Hz, 1 C), 110.9, 110.7, 106.9, 106.5,
64.3, 52.7, 50.5, 22.2.
LRMS (EI, 70 eV): m/z (%) = 314 (M+, 4), 267 (18), 40 (100).
HRMS (EI): m/z for C19H16F2O2 (M+): 314.1118; found: 314.1122.
References
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5-Fluoro-2-[5-fluoro-2-(methoxymethyl)phenyl]-2-methyl-3-
methylene-2,3-dihydro-1H-inden-1-one (18)
Yield: 76.3 mg (81%); colorless oil.
IR (KBr): 2919, 1716 cm–1.
1H NMR (500 MHz, DMSO-d6): δ = 7.63–7.61 (m, 1 H), 7.53–7.50
(m, 1 H), 7.40–7.38 (m, 1 H), 7.20–7.18 (m, 1 H), 7.03–6.99 (m, 1
H), 6.84–6.82 (m, 1 H), 5.67 (s, 1 H), 5.35 (s, 1 H), 4.90 (d, J = 15.5
Hz, 1 H), 4.61 (d, J = 15.5 Hz, 1 H), 3.24 (s, 3 H), 1.44 (s, 3 H).
13C NMR (125 MHz, DMSO-d6): δ = 201.2, 151.7, 140.9, 136.7 (d,
J = 77.0 Hz, 1 C), 135.5, 135.4, 130.0, 124.5 (d, J = 9.0 Hz, 1 C),
117.8 (d, J = 23.0 Hz, 1 C), 114.7 (d, J = 21.5 Hz, 1 C), 112.5 (d,
J = 23.0 Hz, 1 C), 110.9, 110.7, 106.9, 106.5, 64.3, 52.7, 50.5, 22.2.
LRMS (EI, 70 eV): m/z (%) = 314 (M+, 6), 267 (22), 40 (100).
HRMS (EI): m/z calcd for C19H16F2O2 (M+): 314.1118; found:
314.1122.
6-Chloro-2-[4-chloro-2-(methoxymethyl)phenyl]-2-methyl-3-
methylene-2,3-dihydro-1H-inden-1-one (19)
Yield: 62.5 mg (60%); light yellow oil.
IR (KBr): 2919, 1720 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.23–8.17 (m, 2 H), 8.08 (d,
J = 17.5 Hz, 2 H), 7.51 (d, J = 8.0 Hz, 1 H), 7.40 (d, J = 8.5 Hz, 1
H), 5.65 (s, 1 H), 5.17 (s, 1 H), 5.13 (d, J = 16.0 Hz, 1 H), 5.06 (d,
J = 13.0 Hz, 1 H), 3.00 (s, 3 H), 1.67 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 197.2, 153.1, 140.5, 140.1, 138.8,
132.9, 129.5, 127.6, 127.0, 126.9, 125.9, 124.8, 123.7, 121.9, 105.2,
64.9, 52.6, 50.4, 21.8.
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LRMS (EI, 70 eV): m/z (%) = 346 (M+, 25), 316 (100), 276 (22).
HRMS (EI): m/z calcd for C19H16Cl2O2 (M+): 346.0527; found:
346.0531.
2-[2-(Methoxymethyl)-4-nitrophenyl]-2-methyl-3-methylene-6-
nitro-2,3-dihydro-1H-inden-1-one (20)
Yield: 66.2 mg (60%); yellow oil.
IR (KBr): 2925, 1745 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.29–8.23 (m, 2 H), 8.15 (d,
J = 17.0 Hz, 2 H), 7.57 (d, J = 8.5 Hz, 1 H), 7.45 (d, J = 8.0 Hz, 1
H), 5.65 (s, 1 H), 5.23 (s, 1 H), 5.20 (d, J = 16.0 Hz, 1 H), 5.13 (d,
J = 13.5 Hz, 1 H), 3.06 (s, 3 H), 1.73 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 201.3, 149.5, 149.0, 146.0, 142.4,
142.3, 141.5, 132.1, 124.0, 123.9, 123.8, 123.2, 116.9, 110.7, 110.6,
60.4, 51.1, 50.2, 21.0.
LRMS (EI, 70 eV): m/z (%) = 368 (M+, 9), 202 (23), 40 (100).
HRMS (EI): m/z calcd for C19H16N2O6 (M+): 368.1008; found:
368.1012.
Acknowledgment
The authors thank the National Natural Science Foundation of
China (No. 21172060) and Fundamental Research Funds for the
Central Universities (Hunan University) for financial support.
Synthesis 2012, 44, 2049–2057
© Georg Thieme Verlag Stuttgart · New York

PAPER
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(10) The X-ray single-crystal diffraction analysis of 16 is given in
the Supporting Information.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2049–2057