Studies on the synthesis of 2-acyl-1H-indenes via one-pot palladium-catalysed tandem Heck-aldol reaction

Article abstract of DOI:10.3184/030823410X12731659649772

2-Acyl-1H-indenes were synthesised efficiently by the reaction of o-halogenatedbenzaldehydes (or aryl ketones) with prop-2-en-1-ols via one-pot palladium-catalysed tandem Heck-aldol reaction in moderate to good yields. The optimal reaction conditions have

Full text of DOI:10.3184/030823410X12731659649772

254 RESEARCH PAPER
MAY, 254–258
JOURNAL OF CHEMICAL RESEARCH 2010
Studies on the synthesis of 2-acyl-1H-indenes via one-pot
palladium-catalysed tandem Heck–aldol reaction
Song Tua*, Yong Shaa, Long-he Xub, Zong-yuan Xiaoa, Li-yi Yea and Jun Fanga
aDepartment of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen
361005, P. R. China
bState Key Laboratory of Fine Chemicals, Dalian University ofTechnology, Dalian 116023, P. R. China
2-Acyl-1H-indenes were synthesised efficiently by the reaction of o-halogenatedbenzaldehydes (or aryl ketones) with
prop-2-en-1-ols via one-pot palladium-catalysed tandem Heck–aldol reaction in moderate to good yields. The optimal
reaction conditions have been investigated and it was found that sodium acetate was the most effective base and
in addition tetrabutylammonium chloride and LiCl was crucial for this process. Moreover, it was found that
o-halogenatedbenzaldehydes react with various substituted prop-2-en-1-ols smoothly to produce the title compounds
while 2-bromoacetophenone only reacted with 2-propen-1-ol to give the desired product.
Keywords: 2-acyl-1H-indenes, one-pot, palladium-catalysed, tandem Heck–aldol reaction
2-Acylindenes 3 present potential applications in the synthesis
of pharmaceutical and bioactive materials.1,2 This type of
compound has been synthesised first by the reaction of 1H-
indene-2-acyl chloride with LiCu(CH3)2 at –60 °C.3 Other
reported methods normally used highly functionalised materi-
als or suffered a multistep reaction.4–7 In 1996, Dyker and
Grundt reported briefly that 2-acylindenes could be prepared
by palladium-catalysed domino-Heck–aldol-condensation.8
We considered the synthesis of 2-acetylindenes which were
used as key intermediates in our research.9,10 This process
appears promising for the preparation of a wide variety of
2-acylindenes.
This process was shown in Scheme 1. In order to optimise
the reaction conditions and find the scope and limitations
of this process, various factors which might influence this
reaction were investigated. At the same time, various o-
halogenatedbenzaldehydes (or ketones) and prop-2-en-1-ols
were examined. According to our survey, some new conclu-
sions which differed from the reported literature8 were found
and might provide useful information for the synthesis of
2-acylindenes.
Our initial studies focused on the development of optimal
reaction conditions for this process. We used 2-bromobenzal-
dehyde 1a to react with but-3-en-2-ol 2a for this purpose
First, the influence of base, temperature and reaction time to
the reaction were investigated (Table 1). When 1a reacted with
2a at 110 °C using NaHCO3 as base and PPh3 as additive (the
synthetic process reported in literature8), 3a was not obtained
(Table 1, entry 1). It was also found that when using tetrabutyl-
ammonium chloride (TBAC) and LiCl as additive, NaHCO3 or
Et3N were not efficient enough to produce 3a while the Heck-
type products 4a were obtained in moderate yields (Table 1,
entries 2–4). However, when using NaOAc as base, 1a reacted
with 2a to produce the desired product 3a in 67% (Table 1,
entry 5). When 1a reacted with 2a at 90 °C, 3a was not pro-
duced while the Heck-type product 4a was obtained in the
yield of 74% (Table 1, entry 6). It was also found that the yield
of 3a was decreased when 1a reacted with 2a in a longer
reaction time (Table 1, entries 7 and 8 compared with entry 5).
One of the reasons might be was that some other reaction,
such as the intermolecular aldol reaction, would occur under
these reaction conditions. However, if the reaction time was
too short, the yield of 3a was also low because the Heck-type
intermediate 4a could not be transferred to the target
compounds completely (Table 1, entry 9).
It is well known that quaternary ammonium salt (QX)
and lithium chloride are important additives in an Heck-type
reaction.11 So their influence was also investigated (Table 2).
Surprisingly, it was found that the 3a was not produced when
2-bromobenzaldehyde 1a reacted with prop-2-en-1-ol 2a in
the absence of quaternary ammonium salt while the target
product 3a was given in 62% yield using 2 equiv. of tetrabutyl-
ammonium bromide (TBAB) as an additive (Table 2, entries 1
and 2). It was also found when using tetrabutylammonium
chloride (TBAC) instead of TBAB, the yield of product 3a
increased from 62 to 67% (Table 2, entry 3 compared with
entry 2).
There is a possible mechanism that would explain the role of
quaternary ammonium salt (QX) (Fig. 1).11 Quaternary ammo-
nium salt would involve an exchange process with the base
NaOAc to generate the base [n-Bu4NOAc] which is more
efficient to regenerate the Pd(0) catalyst by deprotonation of
hydridopalladium halide in the organic phase. The higher
promoting efficiency of n-Bu4NCl (compared to n-Bu4NBr)
can be explained if its chloride anion acts as a stabilising agent
when there is no phosphine ligand in the reaction mixture.11,12
It was found that the yield of 3a decreased when 1a reacted
with 2a using TBAB as additive without LiCl (Table 2, entry 4
compared with entry 2). However, when 1a reacted with 2a
using TBAC as additive, addition of LiCl had little effect to the
yield of the product (Table 2, entry 5 compared with entry 3).
It was also found that addition of LiCl had little effect to
the yield of product when the more active aryl halide 2-
iodobenzaldehyde 1b reacted with 2a using TBAB as additive
Scheme 1
* Correspondent. E-mail: tusong_2001@hotmail.com

JOURNAL OF CHEMICAL RESEARCH 2010 255
Table 1 The influence of base, temparature and reaction time to the reactiona
Entry
Base
Time/h
Temp./°C
Yield/%b
3a
4a
1
2
3
4
5
6
7
8
9
NaHCO3c
NaHCO3
Et3Ne
24
4
110
110
110
80
110
90
110
110
110
0d
0
62
56
45
0
74
0
Trace
Trace
Trace
67
4
Et3Ne
10
4
4
24
6.5
2
NaOAc
NaOAc
NaOAc
NaOAc
NaOAc
Trace
0d
32d
0
63
28
aGeneral reaction conditions: 2-bromobenzaldehyde 1a (0.5 mmol), prop-2-en-1-ol 2a (0.6 mmol), DMF 5 mL, Pd(OAc)2 (0.025 mmol),
base (1.25 mmol), tetrabutylammonium chloride (TBAC, 1.0 mmol), LiCl (1.0 mmol).
bIsolated yields.
c10 mol% PPh3 and 0.6 mmol NaHCO3 were used without other additives.
dIndeterminate complex compound was produced.
e4.0 mmol Et3N was used.
Table 2 The influence of quaternary ammonium salt (QX) and LiCl to the reactiona
Entry
1
QXb/equiv.
LiClb/equiv.
3a Yield/%c
1
2
1a
1a
1a
1a
1a
1b
1b
1a
1a
1a
none
2.0
0
62
67
29
64
66
67
47
60
67
TBAB 2.0
TBAC 2.0
TBAB 2.0
TBAC 2.0
TBAB 2.0
TBAB 2.0
TBAC 1.0
TBAC 1.5
TBAC 3.0
2.0
3
2.0
4
None
None
None
2.0
5
6
7
8
2.0
9
2.0
10
2.0
aGeneral reaction conditions: o-halogenatedbenzaldehydes 1 (0.5 mmol), prop-2-en-1-ol 2a (0.6 mmol), DMF 5 mL, Pd(OAc)2 (0.025
mmol), NaOAc (1.25 mmol), quaternary ammonium salt (QX), LiCl, 110 °C, 4 hours.
bThe dosage of quaternary ammonium salt (QX) and LiCl based on the aryl halides.
cIsolated yields.
(Table 2, entry 6 compared with entry 7). The role of LiCl can
also be explained by its involving an exchange process with
n-Bu4NBr to generate n-Bu4NCl, which is more efficient for
regenerating the Pd(0) catalyst as mentioned above.11
In order to avoid the intermolecular aldol reaction and other
side reactions, the concentration of the reactants was reduced
by using excessive solvent. So it was believed that the dosage
of additives would influence the reaction when other reaction
conditions had not changed. It was found when 1a reacted
with 2a using the same dosage of LiCl as additive, the yield of
product 3a was decreased with reducing the dosage of TBAC
(Table 2, entries 8 and 9 compared with entry 3). But further
increasing the dosage of TBAC had little effect on the yield of
product 3a (Table 2, entry 10).
According to the above investigations, the optimum reaction
conditions for the synthesis of 2-acylindenes by the reaction
of o-halogenatedbenzaldehydes with prop-2-en-1-ols via a
palladium-catalysed tandem Heck–aldol reaction should be as
follows: o-halogenatedbenzaldehydes 1 reacted with prop-2-
en-1-ols 2 using Pd(OAc)2 (5 mol%) as the catalyst and NaOAc
(2.5 equiv.) as the base; using tetrabutylammonium chloride
(TBAC 2.0 equiv.) and LiCl (2.0 equiv.) as the additives. The
Fig. 1

256 JOURNAL OF CHEMICAL RESEARCH 2010
Table 3 Synthesis of 2-acyl-1H-indenes by palladium-catalysed tandem Heck–aldol reactiona
Entry
1
2
Time /hb
Product 3
Yield /%c
No.
R1
R2
R3
X
No.
R4
1
2
1a
1a
1a
1c
1c
1d
1d
1e
1e
1f
H
H
H
H
H
H
H
H
Cl
Cl
F
H
H
H
H
H
H
H
H
H
H
H
Cl
Cl
H
H
Br
Br
Br
Br
Br
I
2a
2b
2c
2a
2c
2a
2c
2a
2c
2a
2c
2a
2c
2a
2c
Me
Isopropyl
Ph
Me
Ph
Me
Ph
Me
Ph
Me
Ph
Me
Ph
Me
Ph
4
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
67
48
64
64
66
58
62
63
66
61
58
52
54
64
67
H
4
3
H
4
4
Cl
Cl
F
2.5
2.5
2
5
6
7
F
I
2
8
H
Br
Br
Br
Br
I
I
Br
Br
3
9
H
3
10
11
12
13
14
15
H
1.5
1.5
4
1f
H
F
1g
1g
1h
1h
H
H
H
H
H
H
4
CH3
CH3
2
2
16
17
18
1i
1i
1i
H
H
H
Br
Br
Br
2a
2b
2c
Me
Isopropyl
Ph
2
2
2
3p
3q
3r
63
43
63
d
19
1j
NO2
H
H
Br
2a
Me
4
–
0
a General reaction conditions: o-halogenatedbenzaldehydes 1 (1.0 mmol), prop-2-en-1-ols 2 (1.2 mmol), DMF 10 mL, Pd(OAc)2
(0.05 mmol), NaOAc (2.5 mmol), tetrabutylammonium chloride (TBAC, 2.0 mmol), LiCl (2.0 mmol), 110 °C.
b Reaction time was determined by tracing the starting material o-halogenatedbenzaldehydes with TLC analysis.
c Isolated yields.
d Indeterminate complex compound was produced.
Scheme 2
reaction temperature should be 110 °C and the reaction time
should be around 4 hours.
Under the optimal conditions, various o-halogenatedbenzal-
dehydes 1 and prop-2-en-1-ols 2 were tested and 2-acylindenes
3 were produced in moderate to good yields. The results were
summarised in Table 3.
Initially, 2-bromobenzaldehyde 1a was reacted with prop-2-
en-1-ols 2a, 2b and 2c to give the corresponding 2-acylindenes
3a, 3b and 3c in 67, 48 and 64% yields respectively (Table 3,
entries 1–3). At the same time, it was found that the products
3d–k were efficiently prepared in a short time in moderate to
good yields when halogen substituted o-halogenatedbenzalde-
hydes 1c–f reacted with representative prop-2-en-1-ols 2a and
2c respectively (Table 3, entries 4–11). However, when 2-iodo-
6-chlorobenzaldehyde 1g was tested, 2-acylindenes 3l and 3m
were only obtained in 52 and 54% yields (Table 3, entries 12
and 13). But the reaction of 2-bromo-4-methylbenzaldehyde
1h with prop-2-en-1-ols 2a and 2c also gave 2-acyl-indenes 3n
and 3o in good yields efficiently (Table 3, entries 14 and 15).
When the substrate 1i which bearing a strong electron donat-
ing group reacted with prop-2-en-1-ols 2a–c, the title products
3p, 3q and 3r were also obtained in 63, 43 and 63% yields
respectively(Table 3, entries 16–18). However, when 2-bromo-
4-nitrobenzaldehyde 1j was reacted with prop-2-en-1-ol 2a,
the desired product could not be obtained using the same
reaction conditions (Table 3, entry 19).
Next, 2-bromoacetophenone 1k was tested to broaden the
scope of this process (Scheme 2). Surprisingly, under identical
conditions, only prop-2-en-1-ol 2d reacted with 2-bromoace-
tophenone 1k to produce 3s in 54% yield. However, when

JOURNAL OF CHEMICAL RESEARCH 2010 257
Fig. 2
performed on a Vario EL III elementary analysis instrument and the
results were within 0.3% of the calculated value.
other substituted prop-2-en-1-ols 2a and 2c reacted with 2-
bromoacetophenone 1k, only the Heck-type products 4b and
4c were produced in 74 and 73% yields respectively. Under
similar reaction conditions, prolonging the reaction time to 24
hours did not afford the title products. This result also differed
from those reported.8 The in-depth investigation of reaction of
o-halogenated aryl ketones with substituted prop-2-en-1-ols is
now in progress.
A possible mechanism for this one-pot palladium-catalysed
reaction is shown in Fig. 2. First, o-halogenatedbenzaldehydes
(or ketones) 1 react with prop-2-en-1-ols 2 to form the o-acyl
substituted aryl ketones (or aldehydes) 4 by Heck-type reac-
tion with elimination of palladium hydride towards the hydroxy
side and undergoing tautomerisation to the keto forms (or
aldehyde forms).13–15 Then an intramolecular aldol conden-
sation occurs in the presence of NaOAc and produces 2-
acylindenes 3. The possible mechanism of regeneration of
Pd(0) catalyst by deprotonation of hydridopalladium halide
([H–Pd–X]) in the presence of NaOAc and quaternary
ammonium salt (QX) is shown in Fig. 1.
Synthesis of 2-acylindenes 3a–s; general procedure
The o-halogenatedbenzaldehydes (or 2-bromoacetophenone)
1
(1.0 mmol), prop-2-en-1-ols 2 (1.2 mmol), Pd(OAc)2 (5 mol%), tetra-
butylammonium chloride (TBAC) (2.0 mmol), NaOAc (2.5 mmol)
and LiCl (2.0 mmol) were added to a sealed flask. DMF (10 mL) was
added to the flask after the flask was charged with nitrogen. Then the
flask was placed into a 110 °C oil bath and stirring was continued for
1.5–4 hours (as shown in Table 3). The reaction mixture was extracted
with EtOAc (3 × 20 mL) and washed with brine. The combined
organic layers were dried over anhydrous MgSO4 and concentrated
under vacuum. The residue was purified by flash chromatography
(hexane/EtOAc=5/1) to afford products 2-acyl-1H-indenes 3. The
physical and spectra data of the compounds 2k–o are as follows.
1-(1H-Inden-2-yl)ethanone (3a): Yield 67%; yellowish solid; m.p.
57.3–59.0 °C; 1H NMR (CDCl3, 300 MHz) δ: 2.48 (s, 3H), 3.65
(s, 2H), 7.32–7.37 (m, 2H), 7.48–7.55 (m, 2H), 7.62 (s, 1H); IR (KBr)
ν: 1650, 1555, 1460, 1370, 1335, 1190, 880, 760, 720 cm−1. Anal.
Calcd for C11H10O: C, 83.51; H, 6.37. Found: C, 83.36; H, 6.26%.
1-(1H-Inden-2-yl)-2-methylpropan-1-one (3b): Yield 48%; white
1
solid; m.p. 53.2–55.0 °C; H NMR (CDCl3, 300 MHz) δ: 1.19 (d,
We have developed an efficient and convenient process to
synthesise 2-acylindenes via one-pot palladium-catalysed
reaction. It is found that NaOAc is the most effective base and
addition tetrabutylammonium chloride (TBAC) and LiCl is
crucial for this process. Further applications of this methodol-
ogy for the synthesis of bioactive products are also being
investigated in our laboratories.
J = 6.3 Hz, 6H), 3.38–3.68 (m, 1H), 3.69 (s, 2H), 7.35–7.38 (m, 2H),
7.51–7.57 (m, 2H), 7.66 (s, 1H); IR (KBr) ν: 1710, 1660, 1465, 1380,
1025, 755 cm−1. Anal. Calcd for C13H14O: C, 83.83; H, 7.58. Found:
C 83.95; H, 7.39.
(1H-Inden-2-yl)(phenyl)methanone (3c): Yield 64%; yellowish
1
crystal; m.p. 68.4–69.3 °C; H NMR (CDCl3, 300 MHz) δ: 3.88 (s,
2H), 7.34–7.40 (m, 2H), 7.46–7.58 (m, 6H), 7.82–7.85 (m, 2H); IR
(KBr) ν: 1635, 1560, 1345, 1255, 1205, 1115, 760, 710 cm−1. Anal.
Calcd for C16H12O: C, 87.25; H, 5.49. Found: C, 87.03; H, 5.60%.
1-(6-Chloro-1H-inden-2-yl)ethanone (3d): Yield 64%; yellowish
solid; m.p. 71.8–73.6 °C; 1H NMR (CDCl3, 300 MHz) δ: 2.50 (s, 3H),
3.66 (s, 2H), 7.27–7.28 (m, 1H), 7.32 (dd, J = 8.1 Hz, 2.1 Hz, 1H),
7.48–7.50 (m, 1H, ArH), 7.59 (s, 1H); IR (KBr) ν: 1660, 1550, 1365,
1190, 880, 850 cm−1. Anal. Calcd for C11H9ClO: C, 68.58; H, 4.71.
Found: C, 68.72; H, 4.87%.
(6-Chloro-1H-inden-2-yl)(phenyl)methanone (3e): Yield 66%; yel-
lowish solid; m.p. 82.1–83.8 °C; 1H NMR (CDCl3, 300 MHz) δ: 3.84
(s, 2H), 7.36–7.41 (m, 2H), 7.49–7.63 (m, 5H), 7.83–7.85 (m, 2H); IR
(KBr) ν: 1640, 1565, 1345, 1250, 1215, 1120, 760 cm−1. Anal. Calcd
for C16H11ClO: C, 75.45; H, 4.35. Found: C, 75.62; H, 4.21%.
1-(6-Fluoro-1H-inden-2-yl)ethanone (3f): Yield 58%; yellow oil;
1H NMR (CDCl3, 300 MHz) δ: 2.50 (s, 3H), 3.65 (s, 2H), 7.05-7.11
Experimental
Starting materials o-halogenatedbenzaldehydes 1b, 1c, 1e, 1g and 1j
were synthesised according to our previous reports.10 Prop-2-en-1-ols
2b and 2c were synthesised according to the reported literature.16
Other reagents were purchased from Aldrich and used as received.
DMF and Et3N was distilled and dried over 4Å molecular sieves.
Other solvents were obtained from commercial sources and used
without further purification. Silica gel (100–140 mesh) was used for
column chromatography. Melting points were determined on a Buchi
melting point apparatus and are uncorrected. The spectra of 1H NMR
were recorded in CDCl3 solution on a Varian Mercury V×300 NMR
spectrophotometer with TMS as the internal standard. A Perkin-Elmer
983 was used to determine the IR spectra. Elementary analyses were

258 JOURNAL OF CHEMICAL RESEARCH 2010
(m, 1H), 7.20–7.24 (m, 1H), 7.47–7.52 (m, 1H), 7.60 (s, 1H); IR
(KBr) ν: 1645, 1560, 1345, 1250, 1220, 1115, 760 cm−1. Anal. Calcd
for C11H9FO: C, 74.99; H, 5.15. Found: C, 75.13; H, 5.02%.
(6-Fluoro-1H-inden-2-yl)(phenyl)methanone (3g): Yield 62%; yel-
lowish solid; m.p. 71.1–72.6 °C; 1H NMR (CDCl3, 300 MHz) δ: 3.85
(s, 2H), 7.36–7.45 (m, 2H), 7.50–7.66 (m, 5H), 7.87–7.91 (m, 2H); IR
(KBr) ν: 1640, 1560, 1350, 1240, 1215, 1115, 765 cm−1. Anal. Calcd
for C16H11FO: C, 80.66; H, 4.65. Found: C, 80.51; H, 4.78%.
1-(5-Chloro-1H-inden-2-yl)ethanone (3h): Yield 63%; yellowish
solid; m.p. 67.2–68.9 °C; 1H NMR (CDCl3, 300 MHz) δ: 2.50 (s, 3H),
3.65 (s, 2H), 7.30–7.34 (m, 1H), 7.41–7.45 (m, 1H), 7.47–7.58 (m,
2H); IR (KBr) ν: 1660, 1560, 1370, 1220, 1100, 885 cm−1. Anal. Calcd
for C11H9ClO: C, 68.58; H, 4.71. Found: C, 68.69; H, 4.62%.
(5-Chloro-1H-inden-2-yl)(phenyl)methanone (3i): Yield 66%; yel-
lowish solid; m.p. 78.5–80.2 °C; 1H NMR (CDCl3, 300 MHz) δ: 3.86
(s, 2H), 7.32–7.36 (m, 1H), 7.40–7.43 (m, 1H), 7.48–7.66 (m, 5H),
7.87–7.91 (m, 2H); IR (KBr) ν: 1640, 1555, 1360, 1225, 710 cm−1.
Anal. Calcd for C16H11ClO: C, 75.45; H, 4.35. Found: C, 75.59; H,
4.18%.
1-(5-Fluoro-1H-inden-2-yl)ethanone (3j): Yield 61%; white solid;
m.p. 54.3–55.5 °C; 1H NMR (CDCl3, 300 MHz) δ: 2.49 (s, 3H), 3.63
(s, 2H,), 7.02–7.08 (m, 1H), 7.46 (m, 1H), 7.17–7.27 (m, 1H), 7.57–
7.59 (m, 1H); IR (KBr) ν: 1660, 1560, 1375, 1220, 1095, 885 cm−1.
Anal. Calcd for C11H9FO: C, 74.99; H, 5.15. Found: C, 73.97;
H, 5.12%.
(5-Fluoro-1H-inden-2-yl)(phenyl)methanone (3k): Yield 58%;
white solid;, m.p. 69.8–70.7 °C; 1H NMR (CDCl3, 300 MHz) δ: 3.88
(s, 2H), 7.04–7.11 (m, 1H), 7.20–7.30 (m, 1H), 7.44–7.59 (m, 5H),
7.84–7.88 (m, 2H); IR (KBr) ν: 1635, 1560, 1350, 1230, 705 cm−1.
Anal. Calcd for C16H11FO: C, 80.66; H, 4.65. Found: C, 80.63; H,
4.76%.
(5H-Indeno[5,6-d][1,3]dioxol-6-yl)(phenyl)methanone (3r): Yield
63%; yellowish solid; m.p. 144.8–145.5 °C; H NMR (CDCl3, 300
MHz) δ: 3.80 (s, 2H,), 6.02 (s, 2H), 6.97 (s, 1H), 7.05 (s, 1H, ArH),
7.38–7.57 (m, 4H), 7.79–7.81 (m, 2H); IR (KBr) ν: 1625, 1600, 1545,
1470, 1325, 1230, 940, 715 cm−1. Anal. Calcd for C17H12O3: C, 77.26;
H, 4.58. Found: C, 77.16; H, 4.58%.
1
3-Methyl-1H-indene-2-carbaldehyde (3s): Yield 54%; yellow solid;
1
m.p. 74.0–75.2 °C; H NMR (CDCl3, 300 MHz) δ: 2.57 (s, 3H),
3.64 (s, 2H,), 7.40–7.45 (m, 2H), 7.52–7.60 (m, 2H), 10.24 (s, 1H);
IR (KBr) ν: 1645, 1355, 760 cm−1. Anal. Calcd for C11H10O: C, 83.51;
H, 6.37. Found: C, 83.54; H, 6.37%.
Synthesis of Heck-type products 4b and 4c; general procedure
The procedure for the synthesis of Heck-type products 4b and 4c was
similar with the procedure for the synthesis of 2-acylindenes 3a–s.
4-(2-Acetylphenyl)butan-2-one (4b): Yield 74%; Yellow oil; 1H
NMR (CDCl3, 300 MHz) δ: 2.15 (s, 3H), 2.77 (t, 2H, J = 7.8 Hz), 3.28
(t, 2H, J = 7.8 Hz), 7.31–7.39 (m, 1H), 7.41–7.44 (m, 1H), 7.49–7.54
(m, 1H), 7.80 (dd, 1H, J = 7.8 Hz, 1.5 Hz), 10.19 (s, 1H); IR (KBr) ν:
3020, 1725, 1690, 1610, 1580, 1490, 1450, 810 cm−1. Anal. Calcd for
C12H14O2: C, 75.76; H, 7.42. Found: C, 75.62; H, 7.63%.
3-(2-acetylphenyl)-1-phenylpropan-1-one (4c): Yield 73%; brown-
1
ish-yellow oil; H NMR (CDCl3, 300 MHz) δ: 2.16 (s, 3H), 2.60 (s,
3H), 2.78 (t, 2H, J = 7.8 Hz), 3.08 (t, 2H, J = 7.8 Hz), 7.27–7.39 (m,
2H), 7.41–7.44 (m, 1H), 7.70–7.73 (m, 1H); IR (KBr) ν: 3020, 1720,
1640, 1610, 1580, 1480, 800, 760, 710 cm−1. Anal. Calcd for C17H16O2:
C, 80.93; H, 6.39. Found: C, 80.79; H, 6.58%.
This work was supported by High-Tech Research and Devel-
opment Program of China (No. 2008AA05Z107) and National
Nature Science Foundation of China Grant (No. 20876129).
1-(4-Chloro-1H-inden-2-yl)ethanone (3l): Yield 52%; yellowish
solid; m.p. 63.5–64.8 °C; 1H NMR (CDCl3, 300 MHz) δ: 2.44 (s, 3H),
3.61 (s, 2H), 7.21–7.27 (m, 2H), 7.41–7.45 (m, 1H), 7.58 (s, 1H); IR
(KBr) ν: 1645, 1560, 1460, 1360, 1200, 880, 760, 710 cm−1. Anal.
Calcd for C11H9ClO: C, 68.58; H, 4.71. Found: C, 68.47; H, 4.85%.
(4-Chloro-1H-inden-2-yl)(phenyl)methanone (3m): Yield 54%;
Received 4 March 2010; accepted 13 April 2010
Paper 101037 doi: 10.3184/030823410X12731659649772
Published online: 8 June 2010
1
yellowish solid; m.p. 74.2–76.0 °C; H NMR (CDCl3, 300 MHz) δ:
3.88 (s, 2H), 7.24–7.30 (m, 2H), 7.46–7.58 (m, 5H), 7.81–7.84 (m,
2H); IR (KBr) ν: 1640, 1560, 1350, 1255, 1205, 1120, 760, 710 cm−1.
Anal. Calcd for C16H11ClO: C, 75.45; H, 4.35. Found: C, 75.62; H,
4.15%.
1-(6-Methyl-1H-inden-2-yl)ethanone (3n): Yield 64%; yellowish
solid; m.p. 71.3–72.6 °C; 1H NMR (CDCl3, 300 MHz) δ: 2.42 (s, 3H),
2.48 (s, 3H, COCH3), 3.63 (s, 2H), 7.14–7.18 (m, 1H), 7.33–7.45
(m, 2H), 7.58–7.61 (m, 1H); IR (KBr) ν: 1660, 1555, 1370, 1210,
805 cm−1. Anal. Calcd for C12H12O: C, 83.69; H, 7.02. Found: C,
83.50; H, 7.21%.
(6-Methyl-1H-inden-2-yl)(phenyl)methanone (3o): Yield 67%;
yellow solid; m.p. 92.4–93.6 °C; 1H NMR (CDCl3, 300 MHz) δ: 2.43
(s, 3H), 3.63 (s, 2H), 7.15–7.21 (m, 1H), 7.35–7.58 (m, 6H), 7.80–
7.84 (m, 2H); IR (KBr) ν: 1635, 1550, 1345, 1220, 1115, 705 cm−1.
Anal. Calcd for C17H14O: C, 87.15; H, 6.02. Found: C, 87.32; H,
5.91%.
1-(5H-Indeno[5,6-d][1,3]dioxol-6-yl)ethanone (3p): Yield 63%,
white solid; m.p. 149.1–150 °C; 1H NMR (CDCl3, 300 MHz) δ: 2.45
(s, 3H), 3.58 (s, 2H), 6.01 (s, 2H), 6.98 (s, 2H), 7.55 (s, 1H); IR (KBr)
ν: 1650, 1560, 1470, 1220 cm−1. Anal. Calcd for C12H10O3: C, 71.28;
H, 4.98. Found: C, 71.28; H, 4.96%.
References
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11 T. Jeffery, Tetrahedron, 1996, 52, 10113.
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1-(5H-indeno[5,6-d][1,3]dioxol-6-yl)-2-methylpropan-1-one (3q):
1
Yield 43%; yellow solid; m.p. 87.8–89.0 °C; H NMR (CDCl3, 300
MHz) δ: 1.19 (d, J = 6.9 Hz, 6H), 3.36–3.66 (m, 1H), 3.59 (s, 2H),
6.01 (s, 2H), 6.98 (s, 1H), 6.99 (s, 1H), 7.56 (s, 1H); IR (KBr) ν: 1645,
1550, 1465, 1330, 1200, 1160, 1040, 950 cm−1. Anal. Calcd for
C14H14O3: C, 73.03; H, 6.13. Found: C, 73.21; H, 6.01%.
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15 R.C. Larock, E.K. Yum and H. Yang, Tetrahedron, 1994, 50, 305.
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