PtI2-Catalyzed tandem 3,3-rearrangement/Nazarov reaction of arylpropargylic esters: Synthesis of indanone derivatives

Article abstract of DOI:10.1039/c1ob06138k

An efficient PtI₂-catalyzed tandem reaction of arylpropargylic esters, involving 3,3-rearrangement and Nazarov reaction, has been developed to produce 3-substituted and 3,3-disubstituted indanone derivatives. This approach provided a pathway to the synthesis of indanone skeletons in natural products.

Full text of DOI:10.1039/c1ob06138k

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PAPER
PtI2-Catalyzed tandem 3,3-rearrangement/Nazarov reaction of
arylpropargylic esters: synthesis of indanone derivatives†
Huaiji Zheng,a Xingang Xie,a Juan Yang,a Changgui Zhao,a Peng Jing,a Bowen Fanga and Xuegong She*a,b
Received 11th July 2011, Accepted 18th August 2011
DOI: 10.1039/c1ob06138k
An efficient PtI2-catalyzed tandem reaction of arylpropargylic esters, involving 3,3-rearrangement and
Nazarov reaction, has been developed to produce 3-substituted and 3,3-disubstituted indanone
derivatives. This approach provided a pathway to the synthesis of indanone skeletons in natural
products.
As we know, indanones are indeed one of the most useful fami-
lies of compounds, which can be obtained from arylvinylketones,
The development of new pentannulation reactions continues to
since they are the basis of many biologically active compounds
Introduction
such as taiwaniaquinoids5 (Fig. 1) and other medicinally im-
portant products.6 Thus, pentannulation of aromatic rings has
emerged as an important reaction in the arsenal of synthetic
organic chemistry.7 Several methods such as Sarpong’s7b and
Wang’s7g have been developed to achieve this transformation,
which forms 2-indanone derivatives (Schemes 1 and 2). Nolan
and co-workers reported another interesting example of a Au-
catalyzed cycloisomerization of a propargyl acetate containing an
adjacent aryl fragment (Scheme 3).7e While a 1,2-migration of the
acetate was observed in the previously described study, the current
reaction entailed a formal 1,3-migration of the acetate moiety to
give indene.
be an important pursuit in synthetic organic chemistry due to the
prevalence of five-membered rings in natural products. Among a
variety of approaches for their preparation, the Nazarov reaction is
arguably one of the most versatile and efficient methods.1 However,
most synthetically viable applications of the Nazarov reaction have
to include structural elements to control the double bond position
in the enone product (C→D, eq 1). In addition, strong Lewis acids
and one or more equivalents of promoter are required in most
cases. These problems have historically compromised synthetic
utility. Some of these issues were addressed by Denmark’s silicon-
directed or polarized Nazarov cyclization protocol.2,3 Recent
reports on Pd, Pt or Au catalyzed pentannulation reaction of
enynes render the Nazarov reaction a more attractive method
for cyclopentenone synthesis, due to the significant substrate
flexibility and excellent control of the double bond position in
the cyclopentenone ring.4
Fig. 1 Taiwaniaquinoids of indanones.
Scheme 1 Sarpong’s indene synthesis.
Scheme 2 Wang’s indene synthesis.
aState Key Laboratory of Applied Organic Chemistry, College of Chemistry
and Chemical Engineering, Lanzhou University, Gansu, 730000, P. R. China
bState Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou
Institute of Chemical Physic, Chinese Academy of Sciences Lanzhou, Gansu,
730000, P. R. China. E-mail: shexg@lzu.edu.cn; Fax: (+86)931-8912582
Indeed, aromatic Nazarov reactions are well suited for the
construction of the central indanone or indene moieties of these
natural products. A typical Nazarov intermediate 2 was formed
† Electronic supplementary information (ESI) available: 1H and 13C NMR
spectra of 6, 7 and 9. See DOI: 10.1039/c1ob06138k
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proceeded well in a polar solvent (e.g., CH3NO2), however, in
this case the hydrolysis product 7a was isolated as the main
product in 45% yield (entry 9). Then the Pt(IV) catalysts for
this transformation were also examined; inevitably, they led to
the formation of the hydrolysis product 7a (entries 10–13). Then,
replacement of acetate by the benzoate increased the total yield
of 6, 7, and 8 (entries 14–17). Particularly, the yield of 6b
was significantly increased to 84% by using of 10 mol% PtI2
(entry 14).
Scheme 3 Nolan’s indene synthesis.
from 1,3-enyne esters 1 through 3,3-rearrangement and subse-
quent ionization catalyzed by PPh3AuCl/AgSbF6 (Scheme 4).4c
We envisioned that if the olefins are aromatic rings, 1-indanones
would be synthesized via this protocol though the reaction
would require more energy for the disruption of aromaticity. So
therefore, 3,3-rearrangement and Nazarov reaction of 5, followed
by alkylation of the resulting enolate 6 may lead to the formation
of taiwaniaquinoids (Scheme 5). The Nazarov strategy has been
used by Trauner for synthesis of taiwaniaquinoids.8
With the optimized reaction conditions in hand, a series of
arylpropargylic esters were then investigated under our PtI2-
catalyzed tandem protocol, and various synthetically valu-
able 3-substituted indanone derivatives were obtained in high
yield (Table 2). The side chain containing protecting group
(e.g., Bn and TBS) has no negative influence on the reaction,
and 6c–f were obtained in satisfactory yields. However, important
differences in reactivity were observed depending on the starting
t
materials with the bulky groups (iPr and Bu) closer to the site
of cyclization, higher temperature and longer reaction time were
necessary for the formation of 6g and 6h. This tandem cyclization
is also suitable for substrates 5i–p bearing various substituents
(Me, OMe, Br) on the phenyl ring or other aromatic rings
(naphthalene, N-methylindole); the resulting cyclized products 6i–
p were obtained with yields ranging from 42% to 82%. Surprisingly,
the yields of electron-rich phenylpropargylic benzoates were not
as good as general or even weakly electron-deficient aromatic
compounds. This may be due to the occurrence of a series of
side reactions including hydrolysis to form a complex mixture.
Moreover, 6n and 6p were obtained by regioselective cyclization
on the less hindered position, while 7q was obtained from acetate
substrate by regioselective cyclization on the activated posi-
tion. Likewise, heteroaromatic compound 3-thienylpropargylic
acetate could be converted to thienyl cyclopentanone 7r in 81%
yield.
Scheme 4 Tandem 3,3-rearrangement and Nazarov reaction of propar-
gylic esters.
Under the above conditions, 3,3-disubstituted indanone10
derivatives 6s–u (Table 3) were also obtained in good yield by
PtI2 catalyzed cyclization of tertiary arylpropargylic acetates,
although 3,3-disubstituted substrates have significant impact
on the Nazarov cyclization. Conceivably, 6t and its analogue
could be precursors for the synthesis of natural products such
as taiwaniaquinols, dichroanone, standishinal, etc (Fig. 1). For
further construction of the core 6,5,6 tricyclic skeleton, substrate
5v was tested and gave the desired 6,5,6 tricyclic compound 9 in
35% yield (Scheme 6).
Scheme 5 Nazarov strategy for the synthesis of taiwaniaquinoids.
Results and discussion
Initially, arylpropargylic acetate 5a was selected as a model
substrate to investigate this proposed tandem transformation.
PPh3AuCl/AgSbF6 and other Au catalysts (AuCl, AuCl3) proved
ineffective. When 5a was treated with other Lewis acids
(e.g., InCl3, CuCl, AgOTf, AgSbF6), no reaction occurred yet and
5a was recovered in all cases (entries 1–4, Table 1). In the case
of FeCl3 as catalyst, 5a was completely decomposed (entry 5).
Then we turned our attention to Pt catalysts and 6a and 7a
were obtained in 16% and 17% yield respectively when PtCl2 was
used in toluene at 80 ◦C under an atmosphere of CO (1 atm)
(entry 6), the combination of PtCl2 and CO accelerated the
reaction and coordinated the necessary transformation to proceed
(entries 6 and 7).9 The optimal result was further obtained when
PtI2 was used in toluene at 80 ◦C under an atmosphere of CO,
and only the product enol acetate 6a was isolated in 67% yield
with virtually no hydrolysis and uncyclized products (7a and 8a)
being detected in the crude mixture (entry 8). The reaction also
Scheme 6 Formation of [6,5,6] tricyclic skeleton.
Conclusions
We have developed an efficient method for constructing various
3-substituted and 3,3-disubstituted indanone derivatives via the
PtI2-catalyzed tandem 3,3-rearrangement and Nazarov reaction.
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Table 1 Optimization of the tandem cyclization conditions
Yield (%)a
Entry
R
Catalyst (10 mol%)
Solvent
Temp. (◦C)
Time (h)
6
7
8
1
2
3
4
5
6
7
Ac
InCl3
CuCl
AgOTf
AgSbF6
FeCl3
PtCl2/CO
PtCl2/air
PtI2/CO
PtI2/CO
PtCl4/air
PtCl4/CO
PtBr4/CO
PtI4/CO
PtI2/CO
PtCl4/CO
PtBr4/CO
PtI4/CO
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
CH3NO2
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
80
80
80–120
80
80
80
80
80
80
120
80
80
80
80
80
6
2
6
6
0.5
15
12
2
2
3
2
3
2
2
2
3
2
—
—
—
—
/
16
—
67
—
—
—
—
60
84
10
—
54
—
—
—
—
/
17
—
—
45
12
25c
47
24
—
47
68
28
—
—
—
—
b
/
—
—
—
—
54
—
—
—
—
—
—
—
8
9
10
11
12
13
14
15
16
17
Bz
80
80
a Isolated yield; b Decomposed; c over two steps: i) PtCl4 (10 mol%), CO (1 atm), PhMe, 80 ◦C, 2 h; ii) K2CO3, MeOH, rt
Table 2 Various indanones and their derivatives synthesized from the
Table 3 Cyclization of 3,3-disubstituted substrates
PtI2-catalyzed tandem reactiona
a Isolated yield.
Experimental
General methods
All chemicals were used as received. Solvents THF and toluene
were refluxed with Na, CH2Cl2 was refluxed with CaH2 and freshly
distilled prior to use. All reactions under standard conditions
were monitored by thin-layer chromatography (TLC) on gel F254
plates. The silica gel (200–300 meshes) was used for column
chr◦omatography, and the distillation range of petroleum was 60–
1
90 C. H and 13C NMR spectra were recorded on Bruker AM-
400 MHz instrument, and spectral data were reported in ppm
relative to tetramethylsilane (TMS) as internal standard, Chemical
shifts are reported as d values relative to CDCl3 (d = 7.27 for 1H
NMR and 77.0 for 13C NMR). IR spectra were recorded on a
Nicolet FT-170SX spectrometer. HRMS data were determined on
a Bruker Daltonics APEXII 47e FT-ICR spectrometer.
a Reaction conditions: arylpropargylic ester (0.1 M in toluene), 10 mol%
PtI2, CO (1 atm), 80 ◦C, 2 h. b Isolated yield; c Propargylic acetate was
used; d Reaction time of 4 h; e Reaction time of 4 h at 100 ◦C.
Experimental procedures and characterization data
Typical procedure to prepare arylpropargyl esters. To a stirred
solution of the aryl acetylene (3 mmol) in THF (40 ml) was
added BuLi (3 mmol) under Ar at -78 ◦C. An hour later, the
n
This approach provides a pathway to the synthesis of natural
products containing indanone skeletons. Further studies involving
the synthesis of them are ongoing.
aldehyde or ketone (2 mmol) was added and the mixture was slowly
warmed to room temperature and stirred for 2 h. After addition
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of saturated aqueous ammonium chloride (1 ml), the solvent was
removed under reduced pressure and the residue was dissolved in
diethyl ether, washed with brine, dried over anhydrous Na2SO4
and concentrated to give a residue which was purified by column
chromatography (PE–EtOAc = 5 : 1) to afford the corresponding
propargyl alcohol.
To a stirred solution of the propargylic alcohol (1 mmol) in
dichloromethane (10 ml) was added triethylamine (3 mmol), acyl
chloride (1.2 mmol), and DMAP (0.1 mmol) at 0 ◦C. The resultant
mixture was stirred for 1 h at rt, then quenched by addition
of water, washed with brine, dried over anhydrous Na2SO4. The
solvent was removed under reduced pressure, and the residue was
purified by column chromatography (PE–EtOAc = 20 : 1) to afford
the desired arylpropargyl ester 5 (61–93%).
7-tert-Butyldimethylsiloxy-1-phenylhept-1-yn-3-yl benzoate (5f).
63%; H NMR (400 MHz, CDCl3) d ppm 8.13 (d, J = 7.6 Hz,
1
2H), 7.59 (dd, J = 7.6, 7.6 Hz, 1H), 7.47 (dd, J = 7.6, 7.6 Hz,
2H), 7.49–7.45 (m, 2H), 7.33–7.30 (m, 3H), 5.90 (t, J = 6.8 Hz,
1H), 3.68 (t, J = 6.0 Hz, 2H), 2.08–2.03 (m, 2H), 1.72–1.65 (m,
4H), 0.91 (s, 9H), 0.07 (s, 6H); 13C NMR (100 MHz, CDCl3) d
ppm 165.5, 133.0, 131.9, 130.0, 129.8, 128.5, 128.3, 128.2, 122.3,
86.6, 85.4, 65.0, 62.8, 34.8, 32.3, 25.9, 21.6, 18.3, -5.3; IR v (cm-1):
3063, 2953, 2931, 2858, 2234, 1725, 1265, 1100, 837, 770, 757, 711,
691; HRMS (EIS) calcd. for C26H35O3Si [M+H]+: 423.2350, found
423.2354.
4-Methyl-1-phenylpent-1-yn-3-yl benzoate (5g). 86%; 1H NMR
(400 MHz, CDCl3) d ppm 8.13 (d, J = 7.6 Hz, 2H), 7.59 (dd, J =
7.6, 7.6 Hz, 1H), 7.49–7.46 (m, 4H), 7.32–7.30 (m, 3H), 5.73 (d,
J = 5.6 Hz, 1H), 2.31–2.23 (m, 1H), 1.20 (d, J = 6.8 Hz, 3H),
1.17 (d, J = 6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm
165.6, 133.1, 131.9, 130.1, 129.8, 128.5, 128.4, 128.2, 122.5, 85.9,
85.3, 69.9, 32.9, 18.4, 17.8; IR v (cm-1): 3063, 2967, 2230, 1723,
1267, 1101, 757, 710, 690; HRMS (EIS) calcd. for C19H18NaO2
[M+Na]+: 301.1199, found 301.1194.
1-Phenylpent-1-yn-3-yl acetate (5a). 85%; 1H NMR (400 MHz,
CDCl3) d ppm 7.45–7.44 (m, 2H), 7.33–7.29 (m, 3H), 5.67 (t, J =
6.4 Hz, 1H), 2.12 (s, 3H), 1.89 (dq, J = 6.4, 7.2 Hz, 2H), 1.09 (t,
J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 170.0, 131.8,
128.5, 128.2, 122.3, 86.3, 85.2, 65.6, 28.2, 21.0, 9.4; IR v (cm-1):
2973, 2937, 2878, 2237, 1743, 1231, 1019, 758, 692; HRMS (EIS)
calcd. for C13H15O2 [M+H]+: 203.1067, found 203.1065.
4,4-Dimethyl-1-phenylpent-1-yn-3-yl benzoate (5h). 89%; 1H
NMR (400 MHz, CDCl3) d ppm 8.14 (d, J = 7.6 Hz, 2H), 7.60
(dd, J = 7.6, 7.6 Hz, 1H), 7.49 (dd, J = 7.6, 7.6 Hz, 2H), 7.50–7.46
(m, 2H), 7.32–7.29 (m, 3H), 5.61 (s, 1H), 1.21 (s, 9H); 13C NMR
(100 MHz, CDCl3) d ppm 165.6, 133.1, 131.9, 130.1, 129.8, 128.4,
128.3, 128.2, 122.5, 85.8, 85.5, 72.8, 35.8, 25.8; IR v (cm-1): 3063,
2968, 2227, 1724, 1265, 1104, 757, 710, 690; HRMS (EIS) calcd.
for C20H21O2 [M+H]+: 293.1536, found 293.1534.
1-Phenylpent-1-yn-3-yl benzoate (5b). 83%; 1H NMR
(400 MHz, CDCl3) d ppm 8.14 (d, J = 7.6 Hz, 2H), 7.59 (dd, J =
7.6, 7.6 Hz, 1H), 7.48 (dd, J = 7.6, 7.6 Hz, 2H), 7.50–7.46 (m,
2H), 7.33–7.31 (m, 3H), 5.86 (t, J = 6.4 Hz, 1H), 2.07 (dq, J =
6.4, 7.2 Hz, 2H), 1.20 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3) d ppm 165.5, 133.0, 131.8, 130.0, 129.7, 128.5, 128.3,
128.2, 122.3, 86.4, 85.4, 66.1, 28.3, 9.5; IR v (cm-1): 3062, 2973,
2937, 2878, 2237, 1723, 1267, 1099, 757, 711, 691; HRMS (EIS)
calcd. for C18H17O2 [M+H]+: 265.1223, found 265.1220.
1-p-Tolylpent-1-yn-3-yl benzoate (5i). 80%; 1H NMR
(400 MHz, CDCl3) d ppm 8.13 (d, J = 7.6 Hz, 2H), 7.58 (dd, J =
7.6, 7.6 Hz, 1H), 7.46 (dd, J = 7.6, 7.6 Hz, 2H), 7.38 (d, J = 8.0
Hz, 2H), 7.12 (d, J = 8.0 Hz, 2H), 5.85 (t, J = 6.4 Hz, 1H), 2.35
(s, 3H), 2.05 (dq, J = 6.4, 7.2 Hz, 2H), 1.20 (t, J = 7.2 Hz, 3H);
13C NMR (100 MHz, CDCl3) d ppm 165.5, 138.6, 133.0, 131.7,
130.1, 129.7, 128.9, 128.3, 119.3, 85.7, 85.6, 66.2, 28.4, 21.4, 9.5;
IR v (cm-1): 3063, 3031, 2973, 2936, 2235, 1723, 1510, 1453, 1267,
1100, 713, 690; HRMS (EIS) calcd. for C19H18NaO2 [M+Na]+:
301.1199, found 301.1202.
5-Methyl-1-phenylhex-1-yn-3-yl benzoate (5c). 89%; 1H NMR
(400 MHz, CDCl3) d ppm 8.14 (d, J = 7.6 Hz, 2H), 7.59 (dd, J =
7.6, 7.6 Hz, 1H), 7.48 (dd, J = 7.6, 7.6 Hz, 2H), 7.49–7.46 (m, 2H),
7.32–7.31 (m, 3H), 5.94 (t, J = 6.8 Hz, 1H), 2.02–1.88 (m, 3H),
1.06 (d, J = 2.0 Hz, 6H); 13C NMR (100 MHz, CDCl3) d ppm
165.6, 133.1, 131.9, 130.1, 129.8, 128.5, 128.3, 128.2, 122.4, 86.8,
85.3, 63.9, 43.8, 24.9, 22.5; IR v (cm-1): 3063, 2958, 2870, 2202,
1723, 1268, 1101, 757, 711, 690; HRMS (EIS) calcd. for C20H21O2
[M+H]+: 293.1536, found 293.1530.
1-(4-Methoxyphenyl)pent-1-yn-3-yl benzoate (5j). 76%; 1H
NMR (400 MHz, CDCl3) d ppm 8.13 (d, J = 7.6 Hz, 2H), 7.57
(dd, J = 7.6, 7.6 Hz, 1H), 7.46 (dd, J = 7.6, 7.6 Hz, 2H), 7.42 (d,
J = 8.8 Hz, 2H), 6.84 (d, J = 8.8 Hz, 2H), 5.84 (t, J = 6.4 Hz,
1H), 3.79 (s, 3H), 2.05 (dq, J = 6.4, 7.2 Hz, 2H), 1.18 (t, J = 7.2
Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 165.5, 159.7, 133.3,
132.9, 130.1, 129.7, 128.3, 114.4, 113.8, 85.4, 85.0, 66.3, 55.1, 28.4,
9.5; IR v (cm-1): 3066, 2972, 2936, 2231, 1722, 1605, 1510, 1456,
1250, 1176, 1102, 1030, 834, 714, 691; HRMS (EIS) calcd. for
C19H18NaO3 [M+Na]+: 317.1148, found 317.1142.
1,5-Diphenylpent-1-yn-3-yl benzoate (5d). 93%; 1H NMR
(400 MHz, CDCl3) d ppm 8.07 (d, J = 7.6 Hz, 2H), 7.53 (dd,
J = 7.6, 7.6 Hz, 1H), 7.47–7.40 (m, 4H), 7.30–7.16 (m, 8H), 5.87
(t, J = 6.4 Hz, 1H), 2.93 (t, J = 8.0 Hz, 2H), 2.40–2.26 (m, 2H); 13
C
NMR (100 MHz, CDCl3) d ppm 165.4, 140.7, 133.1, 131.9, 129.9,
129.7, 128.6, 128.5, 128.4, 128.3, 128.2, 126.1, 122.2, 86.3, 85.9,
64.5, 36.5, 31.4; IR v (cm-1): 3427, 3062, 3028, 2930, 2861, 2233,
1722, 1601, 1492, 1450, 1264, 1104, 756, 710, 695; HRMS (EIS)
calcd. for C24H21O2 [M+H]+: 341.1536, found 341.1532.
5-(Benzyloxy)-1-phenylpent-1-yn-3-yl acetate (5e). 75%; 1H
NMR (400 MHz, CDCl3) d ppm 7.46–7.30 (m, 10H), 5.87 (t,
J = 6.8 Hz, 1H), 4.56 (s, 2H), 3.76–3.65 (m, 2H), 2.32–2.16 (m,
2H), 2.10 (s, 3H); 13C NMR (100 MHz, CDCl3) d ppm 169.6,
138.0, 131.7, 128.5, 128.2, 128.1, 127.5, 127.4, 122.1, 86.1, 85.3,
72.9, 65.7, 61.9, 35.0, 20.8; IR v (cm-1): 3083, 3061, 2960, 2863,
2232, 1743, 1492, 1370, 1229, 1099, 1021, 757, 695; HRMS (EIS)
calcd. for C20H21O3 [M+H]+: 309.1485, found 309.1482.
1-(4-Bromophenyl)pent-1-yn-3-yl benzoate (5k). 61%; 1H
NMR (400 MHz, CDCl3) d ppm 8.12 (d, J = 7.6 Hz, 2H), 7.58
(dd, J = 7.6, 7.6 Hz, 1H), 7.49–7.43 (m, 4H), 7.32 (d, J = 6.8 Hz,
2H), 5.81 (t, J = 6.4 Hz, 1H), 2.04 (dq, J = 6.4, 7.2 Hz, 2H), 1.17 (t,
J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 165.5, 133.3,
133.1, 131.5, 129.9, 129.7, 128.3, 122.8, 121.3, 87.6, 84.3, 66.0,
28.2, 9.5; IR v (cm-1): 3065, 2973, 2937, 2238, 1723, 1486, 1266,
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1099, 1069, 825, 711, 688; HRMS (EIS) calcd. for C18H16BrO2
[M+H]+: 343.0328, found 343.0324.
(s, 3H), 1.93 (dq, J = 6.4, 7.2 Hz, 2H), 1.13 (t, J = 7.2 Hz, 3H);
13C NMR (100 MHz, CDCl3) d ppm 170.1, 136.4, 129.7, 128.1,
125.2, 125.1, 112.7, 109.1, 101.1, 87.0, 83.8, 65.9, 32.7, 28.3, 21.1,
9.4; IR v (cm-1): 2972, 2937, 2224, 1738, 1488, 1372, 1332, 1233,
1016, 723; HRMS (EIS) calcd. for C16H18NO2 [M+H]+: 256.1332,
found 256.1335.
1-o-Tolylpent-1-yn-3-yl benzoate (5l). 88%; 1H NMR
(400 MHz, CDCl3) d ppm 8.11 (d, J = 7.6 Hz, 2H), 7.56 (dd, J =
7.6, 7.6 Hz, 1H), 7.44 (dd, J = 7.6, 7.6 Hz, 2H), 7.41 (d, J = 7.2
Hz, 1H), 7.23–7.16 (m, 2H), 7.11 (dd, J = 6.8, 6.8 Hz, 1H), 5.85
(t, J = 6.4 Hz, 1H), 2.43 (s, 3H), 2.04 (dq, J = 6.4, 7.2 Hz, 2H),
1.17 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm
165.6, 140.4, 133.0, 132.1, 130.1, 129.7, 129.3, 128.5, 128.3, 125.4,
122.1, 90.3, 84.4, 66.3, 28.4, 20.6, 9.5; IR v (cm-1): 3065, 2973,
2937, 2231, 1723, 1266, 1099, 759, 712, 689; HRMS (EIS) calcd.
for C19H18NaO2 [M+Na]+: 301.1199, found 301.1193.
1
1-(Thiophen-3-yl)pent-1-yn-3-yl acetate (5r). 76%; H NMR
(400 MHz, CDCl3) d ppm 7.45 (d, J = 2.8 Hz, 1H), 7.24 (dd, J =
2.8, 5.2 Hz, 1H), 7.10 (d, J = 5.2 Hz, 1H), 5.53 (t, J = 6.4 Hz,
1H), 2.10 (s, 3H), 1.86 (dq, J = 6.4, 7.2 Hz, 2H), 1.06 (t, J = 7.2
Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 169.9, 129.9, 129.3,
125.2, 121.3, 86.0, 80.3, 65.6, 28.1, 20.9, 9.3; IR v (cm-1): 3109,
2973, 2937, 2239, 1742, 1368, 1232, 1018, 785, 627; HRMS (EIS)
calcd. for C11H13O2S [M+H]+: 209.0631, found 209.0634.
1-(2-Methoxyphenyl)pent-1-yn-3-yl benzoate (5m). 77%; 1H
NMR (400 MHz, CDCl3) d ppm 8.10 (d, J = 7.6 Hz, 2H), 7.54 (dd,
J = 7.6, 7.6 Hz, 1H), 7.42 (dd, J = 7.6, 7.6 Hz, 2H), 7.41 (d, J = 8.0
Hz, 1H), 7.26 (dd, J = 8.0, 8.0 Hz, 1H), 6.87 (dd, J = 8.0, 8.0 Hz,
1H), 6.82 (d, J = 8.0 Hz, 1H), 5.89 (t, J = 6.4 Hz, 1H), 3.82 (s, 3H),
2.04 (dq, J = 6.4, 7.2 Hz, 2H), 1.17 (t, J = 7.2 Hz, 3H); 13C NMR
(100 MHz, CDCl3) d ppm 165.5, 160.2, 133.8, 132.9, 130.1, 129.9,
129.7, 128.2, 120.2, 111.5, 110.6, 90.3, 81.8, 66.4, 55.6, 28.4, 9.4;
IR v (cm-1): 3067, 2972, 2938, 2234, 1721, 1493, 1457, 1265, 1099,
754, 712; HRMS (EIS) calcd. for C19H19O3 [M+H]+: 295.1329,
found 295.1328.
(5n). 74%; 1H NMR (400 MHz, CDCl3) d ppm 8.13 (d, J = 7.6
Hz, 4H), 7.56 (dd, J = 7.6, 7.6 Hz, 2H), 7.46 (dd, J = 7.6, 7.6 Hz,
4H), 7.41 (s, 4H), 5.83 (t, J = 6.4 Hz, 2H), 2.05 (dq, J = 6.4, 7.2 Hz,
4H), 1.18 (t, J = 7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3) d ppm
165.5, 133.0, 131.6, 129.9, 129.7, 128.3, 122.5, 88.3, 84.9, 66.0,
28.2, 9.5; IR v (cm-1): 3065, 2972, 2934, 2877, 2232, 1721, 1264,
1096, 710; HRMS (EIS) calcd. for C30H27O4 [M+H]+: 451.1904,
found 451.1906.
5-tert-Butyldimethylsiloxy-3-methyl-1-phenylpent-1-yn-3-yl ac-
1
etate (5s). 70%; H NMR (400 MHz, CDCl3) d ppm 7.44–7.41
(m, 2H), 7.29–7.26 (m, 3H), 3.97–3.86 (m, 2H), 2.35–2.28 (m,
1H), 2.20–2.13 (m, 1H), 2.04 (s, 3H), 1.79 (s, 3H), 0.91 (s, 9H),
0.08 (s, 6H); 13C NMR (100 MHz, CDCl3) d ppm 169.1, 131.8,
128.3, 128.1, 122.6, 88.9, 85.3, 74.4, 59.5, 43.9, 27.2, 25.9, 22.0,
18.2, -5.3; IR v (cm-1): 2955, 2932, 2887, 2857, 2236, 1748, 1368,
1236, 1104, 839, 778, 757, 691; HRMS (EIS) calcd. for C20H31O3Si
[M+H]+: 347.2037, found 347.2033.
7-Methoxy-3,7-dimethyl-1-phenyloct-1-yn-3-yl acetate (5t).
1
81%; H NMR (400 MHz, CDCl3) d ppm 7.44–7.41 (m, 2H),
7.29–7.27 (m, 3H), 3.18 (s, 3H), 2.07–1.99 (m, 1H), 2.04 (s, 3H),
1.92–1.83 (m, 1H), 1.76 (s, 3H), 1.65–1.49 (m, 4H), 1.20 (s, 6H);
13C NMR (100 MHz, CDCl3) d ppm 169.2, 131.7, 128.2, 128.1,
122.7, 89.4, 85.0, 75.6, 74.4, 49.0, 41.9, 39.6, 26.5, 24.9, 24.9, 21.9,
18.7; IR v (cm-1): 2973, 2941, 2235, 1745, 1368, 1238, 1155, 1079,
758, 693; HRMS (EIS) calcd. for C19H27O3 [M+H]+: 303.1955,
found 303.1954.
1-(Naphthalen-4-yl)pent-1-yn-3-yl benzoate (5o). 63%; 1H
NMR (400 MHz, CDCl3) d ppm 8.35 (d, J = 8.4 Hz, 1H), 8.14
(d, J = 7.6 Hz, 2H), 7.81 (dd, J = 5.2, 8.0 Hz, 2H), 7.70 (d, J =
6.8 Hz, 1H), 7.59–7.37 (m, 6H), 6.39 (t, J = 6.4 Hz, 1H), 2.15
(dq, J = 6.4, 7.2 Hz, 2H), 1.26 (t, J = 7.2 Hz, 3H); 13C NMR
(100 MHz, CDCl3) d ppm 165.6, 133.3, 133.1, 133.0, 130.8, 130.0,
129.7, 129.0, 128.3, 128.2, 126.8, 126.3, 126.0, 125.0, 119.9, 91.3,
83.6, 66.4, 55.6, 28.4, 9.6; IR v (cm-1): 3060, 2973, 2936, 2878, 2226,
1722, 1265, 1103, 801, 774, 712; HRMS (EIS) calcd. for C22H19O2
[M+H]+: 315.1380, found 315.1376.
1-(2-Phenylethynyl)cyclobutyl acetate (5u). 87%; 1H NMR
(400 MHz, CDCl3) d ppm 7.47–7.45 (m, 2H), 7.31–7.27 (m, 3H),
2.71–2.65 (m, 2H), 2.54–2.46 (m, 2H), 2.08 (s, 3H), 2.04–1.89 (m,
2H); 13C NMR (100 MHz, CDCl3) d ppm 169.0, 131.8, 128.3,
128.1, 122.6, 89.2, 84.2, 72.2, 36.8, 21.3, 14.6; IR v (cm-1): 3000,
2952, 2227, 1746, 1236, 1096, 758, 692; HRMS (EIS) calcd. for
C14H15O2 [M+H]+: 215.1067, found 215.1066.
1,9-Diphenyl-1,8-diyn-3,7-diyl acetate (5v). 76%; 1H NMR
(400 MHz, CDCl3) d ppm 7.44–7.42 (m, 4H), 7.34–7.24 (m, 6H),
5.66 (t, J = 6.4 Hz, 2H), 2.12 (s, 6H), 1.98–1.93 (m, 4H), 1.82–1.77
(m, 2H); 13C NMR (100 MHz, CDCl3) d ppm 169.9, 131.8, 128.6,
128.2, 122.1, 86.1, 85.6, 64.2, 34.2, 21.0, 20.8; IR v (cm-1): 3059,
2931, 2868, 2232, 1743, 1231, 1020, 758, 692; HRMS (EIS) calcd.
for C25H25O4 [M+H]+: 389.1747, found 389.1741.
1-(1-Methyl-1H-indol-5-yl)pent-1-yn-3-yl benzoate (5p). 62%;
1H NMR (400 MHz, CDCl3) d ppm 8.11 (d, J = 7.6 Hz, 2H), 7.76
(s, 1H), 7.55 (dd, J = 7.6, 7.6 Hz, 1H), 7.43 (dd, J = 7.6, 7.6 Hz,
2H), 7.30 (d, J = 8.4 Hz, 1H), 7.22 (d, J = 8.4 Hz, 1H), 7.02 (d,
J = 3.2 Hz, 1H), 6.43 (d, J = 3.2 Hz, 1H), 5.86 (t, J = 6.4 Hz,
1H), 3.73 (s, 3H), 2.04 (dq, J = 6.4, 7.2 Hz, 2H), 1.18 (t, J = 7.2
Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 165.7, 136.4, 132.9,
130.3, 129.8, 129.7, 128.3, 128.2, 125.3, 125.2, 112.8, 109.1, 101.2,
87.1, 83.9, 66.6, 32.8, 28.6, 9.6; IR v (cm-1): 3063, 2972, 2937,
2223, 1719, 1266, 1104, 713; HRMS (EIS) calcd. for C21H20NO2
[M+H]+: 318.1489, found 318.1485.
Typical procedure for the cyclization reactions
A suspension of the arylpropargylic ester (0.15 mmol) and PtI2
(0.015 mmol) in toluene (1.5 ml) under CO (1 atm) at 80 ◦C was
stirred until the starting material disappeared. Then the mixture
was allowed to cool down to room temperature, and the suspension
was directly loaded onto a silica gel column, elution with a 50 : 1
mixture of PE–EtOAc yielded the desired product.
1-(1-Methyl-1H-indol-5-yl)pent-1-yn-3-yl acetate (5q). 66%;
1H NMR (400 MHz, CDCl3) d ppm 7.79 (s, 1H), 7.32 (dd, J =
1.6, 8.4 Hz, 1H), 7.23 (d, J = 8.4 Hz, 1H), 7.05 (d, J = 2.8 Hz, 1H),
6.46 (d, J = 2.8 Hz, 1H), 5.64 (t, J = 6.4 Hz, 1H), 3.75 (s, 3H), 2.14
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1
1-Ethyl-1H-inden-3-yl acetate (6a). oil; H NMR (400 MHz,
(m, 1H), 1.65–1.45 (m, 5H), 0.93 (s, 9H), 0.08 (s, 6H); 13C NMR
(100 MHz, CDCl3) d ppm 163.8, 148.4, 146.0, 138.8, 133.6, 130.1,
129.6, 128.6, 126.5, 125.9, 123.1, 120.4, 118.1, 63.0, 46.8, 33.0,
31.6, 26.0, 23.9, 18.3, -5.3; IR v (cm-1): 3067, 2952, 2930, 2858,
1742, 1466, 1258, 11020, 837, 776, 708; HRMS (EIS) calcd. for
C26H38NO3Si [M+NH4]+: 440.2615, found 440.2620.
CDCl3) d ppm 7.40 (d, J = 6.8 Hz, 1H), 7.28–7.22 (m, 3H), 6.35
(d, J = 2.0 Hz, 1H), 3.49–3.45 (m, 1H), 2.32 (s, 3H), 2.05–1.94
(m, 1H), 1.64–1.53 (m, 1H), 0.96 (t, J = 7.2 Hz, 3H); 13C NMR
(100 MHz, CDCl3) d ppm 168.1, 148.4, 145.8, 138.7, 126.4, 125.8,
123.0, 120.0, 118.0, 47.9, 24.6, 21.2, 11.6; IR v (cm-1): 3067, 2966,
2930, 2875, 1728, 1206, 759; HRMS (EIS) calcd. for C13H15O2
[M+H]+: 203.1067, found 203.1062.
1-Isopropyl-1H-inden-3-yl benzoate (6g). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.26 (d, J = 7.6 Hz, 2H), 7.64 (dd,
J = 7.6, 7.6 Hz, 1H), 7.53 (dd, J = 7.6, 7.6 Hz, 2H), 7.45 (d, J =
7.2 Hz, 1H), 7.40 (d, J = 6.8 Hz, 1H), 7.34–7.25 (m, 2H), 6.48
(d, J = 2.0 Hz, 1H), 3.57 (dd, J = 2.0, 4.0 Hz, 1H), 2.47–2.40 (m,
1H), 1.18 (d, J = 7.2 Hz, 3H), 0.71 (d, J = 7.2 Hz, 3H); 13C NMR
(100 MHz, CDCl3) d ppm 163.9, 148.8, 145.1, 139.4, 133.6, 130.1,
129.5, 128.6, 126.4, 125.7, 118.1, 118.0, 53.2, 30.1, 21.5, 17.5; IR v
(cm-1): 3066, 2961, 2929, 2873, 1740, 1260, 1120, 760, 708; HRMS
(EIS) calcd. for C19H19O2 [M+H]+: 279.1380, found 279.1381.
3-Ethyl-2,3-dihydroinden-1-one (7a/b). This product has been
synthesized before: A. Sani-Souna-Sido, S. Chassaing, P. Pale, and
J. Sommer, Appl. Catal., A 2008, 336, 101.
1-Ethyl-1H-inden-3-yl benzoate (6b). oil; 1H NMR (400 MHz,
CDCl3) d ppm 8.25 (d, J = 7.6 Hz, 2H), 7.62 (dd, J = 7.6, 7.6 Hz,
1H), 7.51 (dd, J = 7.6, 7.6 Hz, 2H), 7.43 (d, J = 7.2 Hz, 1H), 7.39
(d, J = 6.8 Hz, 1H), 7.32–7.22 (m, 2H), 6.52 (d, J = 2.4 Hz, 1H),
3.56–3.52 (m, 1H), 2.09–1.99 (m, 1H), 1.69–1.58 (m, 1H), 1.00
(t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 163.8,
148.5, 145.8, 138.9, 133.6, 130.1, 129.5, 128.6, 126.5, 125.8, 123.1,
120.2, 118.1, 48.1, 24.6, 11.6; IR v (cm-1): 3067, 2964, 2928, 1737,
1261, 1120, 759, 708; HRMS (EIS) calcd. for C18H17O2 [M+H]+:
265.1223, found 265.1222.
1-tert-Butyl-1H-inden-3-yl benzoate (6h). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.27 (d, J = 7.6 Hz, 2H), 7.67 (dd,
J = 7.6, 7.6 Hz, 1H), 7.58 (dd, J = 7.6, 7.6 Hz, 2H), 7.54 (d, J = 7.6
Hz, 1H), 7.39 (d, J = 7.6 Hz, 1H), 7.33 (dd, J = 7.6, 7.6 Hz, 1H),
7.26 (dd, J = 7.6 Hz, 1h), 6.54 (d, J = 2.4 Hz, 1H), 3.43 (d, J = 2.4
Hz, 1H), 1.11 (s, 9H); 13C NMR (100 MHz, CDCl3) d ppm 163.9,
148.7, 144.0, 139.8, 133.6, 130.1, 129.6, 128.6, 126.4, 125.4, 125.1,
119.6, 117.9, 57.8, 34.5, 28.5; IR v (cm-1): 3066, 2960, 2868, 1740,
1261, 1122, 760, 706; HRMS (EIS) calcd. for C20H21O2 [M+H]+:
293.1536, found 293.1541.
1-Isobutyl-1H-inden-3-yl benzoate (6c). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.25 (d, J = 7.6 Hz, 2H), 7.62 (dd, J =
7.6, 7.6 Hz, 1H), 7.52 (dd, J = 7.6, 7.6 Hz, 2H), 7.43 (d, J = 7.2
Hz, 1H), 7.39 (d, J = 6.8 Hz, 1H), 7.32–7.23 (m, 2H), 6.56 (d, J =
2.0 Hz, 1H), 3.66–3.62 (m, 1H), 1.93–1.83 (m, 1H), 1.79–1.72 (m,
1H), 1.43–1.36 (m, 1H), 1.07 (d, J = 6.8 Hz, 3H), 0.98 (d, J = 6.8
Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 163.9, 148.4, 146.6,
138.6, 133.6, 130.1, 129.6, 128.6, 126.4, 125.8, 123.2, 120.6, 118.2,
45.0, 41.1, 27.4, 23.6, 22.3; IR v (cm-1): 3067, 2957, 2927, 2870,
1737, 1261, 1120, 758, 708; HRMS (EIS) calcd. for C20H21O2
[M+H]+: 293.1536, found 293.1539.
1-Ethyl-6-methyl-1H-inden-3-yl benzoate (6i). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.27 (d, J = 7.6 Hz, 2H), 7.66 (dd,
J = 7.6, 7.6 Hz, 1H), 7.55 (dd, J = 7.6, 7.6 Hz, 2H), 7.30 (d, J = 8.0
Hz, 1H), 7.29 (s, 1H), 7.15 (d, J = 8.0 Hz, 1H), 6.48 (d, J = 2.4 Hz,
1H), 3.56–3.52 (m, 1H), 2.45 (s, 3H), 2.12–2.01 (m, 1H), 1.72–1.61
(m, 1H), 1.04 (t, J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) d
ppm 163.9, 148.5, 146.2, 136.3, 135.6, 133.5, 130.1, 129.7, 128.6,
127.2, 124.0, 119.2, 117.8, 47.9, 24.8, 21.6, 11.7; IR v (cm-1): 2964,
2926, 2868, 1742, 1259, 1135, 1097, 817, 706; HRMS (EIS) calcd.
for C19H18NaO2 [M+Na]+: 301.1199, found 301.1201.
1-Phenethyl-1H-inden-3-yl benzoate (6d). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.25 (d, J = 7.6 Hz, 2H), 7.63 (dd,
J = 7.6, 7.6 Hz, 1H), 7.52 (dd, J = 7.6, 7.6 Hz, 2H), 7.44 (d, J =
6.8 Hz, 1H), 7.41 (d, J = 7.2 Hz, 1H), 7.34–7.16 (m, 7H), 6.59
(d, J = 2.0 Hz, 1H), 3.66–3.62 (m, 1H), 2.81–2.66 (m, 2H), 2.35–
2.27 (m, 1H), 1.96–1.86 (m, 1H); 13C NMR (100 MHz, CDCl3) d
ppm 163.8, 148.7, 145.7, 142.1, 138.8, 133.6, 130.1, 129.5, 128.6,
128.4, 126.6, 126.0, 125.9, 123.1, 119.9, 118.2, 46.4, 33.6, 33.5; IR v
(cm-1): 3063, 3026, 2923, 2856, 1741, 1259, 1121, 759, 704; HRMS
(EIS) calcd. for C24H20NaO2 [M+Na]+: 363.1356, found 363.1361.
1-Ethyl-6-methoxy-1H-inden-3-yl benzoate (6j). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.24 (d, J = 7.6 Hz, 2H), 7.66 (dd, J =
7.6, 7.6 Hz, 1H), 7.54 (dd, J = 7.6, 7.6 Hz, 2H), 7.29 (d, J = 8.4
Hz, 1H), 7.04 (d, J = 2.0 Hz, 1H), 6.87 (dd, J = 8.4, 2.4 Hz, 1H),
6.39 (d, J = 2.4 Hz, 1H), 3.86 (s, 3H), 3.55–3.51 (m, 1H), 2.10–1.99
(m, 1H), 1.71–1.60 (m, 1H), 1.02 (t, J = 7.6 Hz, 3H); 13C NMR
(100 MHz, CDCl3) d ppm 163.9, 158.9, 148.3, 147.8, 133.5, 132.0,
130.1, 129.7, 128.6, 118.6, 118.1, 111.9, 109.9, 55.6, 47.9, 24.9,
11.5; IR v (cm-1): 2963, 2920, 2856, 1737, 1602, 1255, 1129, 708;
HRMS (EIS) calcd. for C19H18NaO3 [M+Na]+: 317.1148, found
317.1145.
1-(2-(Benzyloxy)ethyl)-1H-inden-3-yl acetate (6e). oil; 1H
NMR (400 MHz, CDCl3) d ppm 7.38–7.23 (m, 9H), 6.38 (d, J =
2.0 Hz, 1H), 4.54 (s, 2H), 3.75–3.71 (m, 1H), 3.63 (t, J = 6.4 Hz,
2H), 2.33 (s, 3H), 2.30–2.24 (m, 1H), 1.85–1.76 (m, 1H); 13C NMR
(100 MHz, CDCl3) d ppm 168.1, 148.4, 145.7, 138.5, 138.4, 128.3,
127.6, 127.5, 126.5, 125.9, 123.2, 119.9, 118.1, 73.0, 68.6, 43.7,
31.7, 21.1; IR v (cm-1): 3063, 3031, 2929, 2862, 1726, 1606, 1457,
1366, 1209, 1110, 743, 700; HRMS (EIS) calcd. for C20H20NaO3
[M+Na]+: 331.1305, found 331.1311.
6-Bromo-1-ethyl-1H-inden-3-yl benzoate (6k). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.21 (d, J = 7.6 Hz, 2H), 7.63 (dd,
J = 7.6, 7.6 Hz, 1H), 7.54 (dd, J = 7.6, 7.6 Hz, 2H), 7.51 (d, J = 7.6
Hz, 1H), 7.43 (d, J = 8.0 Hz, 1H), 7.23 (d, J = 8.0 Hz, 1H), 6.50 (d,
J = 2.4 Hz, 1H), 3.55–3.51 (m, 1H), 2.07–1.96 (m, 1H), 1.69–1.58
(m, 1H), 0.98 (t, J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) d
ppm 163.7, 147.9, 147.8, 137.9, 133.7, 130.1, 129.6, 129.3, 128.6,
126.5, 120.6, 120.1, 119.4, 48.1, 24.4, 11.5; IR v (cm-1): 3065, 2965,
1-(4-tert-Butyldimethylsiloxybutyl)-1H-inden-3-yl benzoate (6f).
oil; 1H NMR (400 MHz, CDCl3) d ppm 8.27 (d, J = 7.6 Hz, 2H),
7.67 (dd, J = 7.6, 7.6 Hz, 1H), 7.56 (dd, J = 7.6, 7.6 Hz, 2H),
7.48 (d, J = 7.2 Hz, 1H), 7.42 (d, J = 7.2 Hz, 1H), 7.36–7.27
(m, 2H), 6.56 (d, J = 2.0 Hz, 1H), 3.66–3.61 (m, 3H), 2.05–2.01
7760 | Org. Biomol. Chem., 2011, 9, 7755–7762
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2929, 2872, 1743, 1259, 1129, 1101, 818, 706; HRMS (EIS) calcd.
for C18H15BrKO2 [M+K]+: 380.9887, found 380.9896.
Hz, 2H), 7.65 (dd, J = 7.6, 7.6 Hz, 1H), 7.55 (dd, J = 7.6, 7.6 Hz,
2H), 7.30 (s, 1H), 7.29 (s, 1H), 7.12 (d, J = 3.2 Hz, 1H), 6.58 (d,
J = 3.2 Hz, 1H), 6.44 (d, J = 1.6 Hz, 1H), 3.83 (s, 3H), 3.83–3.78
(m, 1H), 2.40–2.30 (m, 1H), 1.78–1.67 (m, 1H), 0.97 (t, J = 7.6
Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 164.8, 153.0, 148.8,
148.7, 133.1, 130.1, 130.0, 128.4, 127.2, 126.4, 120.0, 116.2, 109.5,
55.4, 47.7, 24.7, 11.4; IR v (cm-1): 2961, 2924, 2870, 1738, 1260,
1123, 794, 707; HRMS (EIS) calcd. for C21H20NO2 [M+H]+:
318.1489, found 318.1496.
1-Ethyl-4-methyl-1H-inden-3-yl benzoate (6l). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.25 (d, J = 7.6 Hz, 2H), 7.67 (dd,
J = 7.6, 7.6 Hz, 1H), 7.56 (dd, J = 7.6, 7.6 Hz, 2H), 7.31 (d, J =
7.6 Hz, 1H), 7.19 (dd, J = 7.6, 7.6 Hz, 1H), 7.08 (d, J = 7.6 Hz,
1H), 6.50 (d, J = 2.4 Hz, 1H), 3.55–3.51 (m, 1H), 2.57 (s, 3H),
2.13–2.03 (m, 1H), 1.70–1.59 (m, 1H), 1.03 (t, J = 7.6 Hz, 3H); 13
C
NMR (100 MHz, CDCl3) d ppm 164.5, 149.8, 146.7, 136.6, 133.5,
130.0, 129.8, 129.7, 129.0, 128.7, 125.8, 121.4, 120.9, 47.4, 24.8,
19.0, 11.5; IR v (cm-1): 3065, 2964, 2928, 2867, 1741, 1252, 1110,
769, 706; HRMS (EIS) calcd. for C19H19O2 [M+H]+: 279.1380,
found 279.1384.
8-Ethyl-7,8-dihydro-3-methylcyclopenta[e]indol-6(3H)-one (7q).
◦
1
solid, mp:102–104 C; H NMR (400 MHz, CDCl3) d ppm 7.61
(d, J = 8.4 Hz, 1H), 7.32 (d, J = 8.4 Hz, 1H), 7.17 (d, J = 2.8 Hz,
1H), 6.69 (d, J = 2.8 Hz, 1H), 6.44 (d, J = 1.6 Hz, 1H), 3.86 (s, 3H),
3.66–3.60 (m, 1H), 2.90 (dd, J = 7.6, 18.8 Hz, 1H), 2.47 (dd, J =
2.4, 18.8 Hz, 1H), 2.28–2.18 (m, 1H), 1.71–1.60 (m, 1H), 0.95 (t,
J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 206.2, 154.5,
140.0, 129.9, 129.5, 124.7, 116.7, 109.6, 101.2, 42.5, 39.2, 33.3,
27.8, 11.3; IR v (cm-1): 2961, 2928, 2874, 1692, 1300, 1094, 1055,
801, 735; HRMS (EIS) calcd. for C14H16NO [M+H]+: 214.1226,
found 214.1228.
1-Ethyl-4-methoxy-1H-inden-3-yl benzoate (6m). oil; 1H NMR
(400 MHz, CDCl3) d ppm 8.24 (d, J = 7.6 Hz, 2H), 7.64 (dd, J =
7.6, 7.6 Hz, 1H), 7.53 (dd, J = 7.6, 7.6 Hz, 2H), 7.22 (dd, J =
7.6, 7.6 Hz, 1H), 7.07 (d, J = 7.6 Hz, 1H), 6.79 (d, J = 7.6 Hz,
1H), 6.23 (d, J = 2.0 Hz, 1H), 3.69 (s, 3H), 3.55–3.51 (m, 1H),
2.10–2.00 (m, 1H), 1.70–1.59 (m, 1H), 1.00 (t, J = 7.6 Hz, 3H);
13C NMR (100 MHz, CDCl3) d ppm 164.8, 153.0, 148.8, 148.7,
133.1, 130.1, 130.0, 128.4, 127.2, 126.4, 120.0, 116.2, 109.5, 55.4,
47.7, 24.7, 11.4; IR v (cm-1): 3066, 2963, 2929, 2869, 1740, 1263,
1101, 1062, 776, 747, 707; HRMS (EIS) calcd. for C19H18NaO3
[M+Na]+: 317.1148, found 317.1150.
(6n). oil; 1H NMR (400 MHz, CDCl3) d ppm 8.28 (d, J = 7.6 Hz,
4H), 7.68 (dd, J = 7.6, 7.6 Hz, 2H), 7.57 (dd, J = 7.6, 7.6 Hz, 4H),
7.45 (s, 2H), 6.54 (d, J = 2.0 Hz, 2H), 3.61–3.56 (m, 2H), 2.18–2.08
(m, 2H), 1.72–1.61 (m, 2H), 1.04 (t, J = 7.6 Hz, 3H), 1.01 (t, J = 7.6
Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 163.9, 148.6, 145.1,
137.4, 133.6, 130.1, 129.7, 128.7, 120.2, 113.1, 47.9, 24.9, 11.5; IR
v (cm-1): 2962, 2927, 2871, 1740, 1259, 1177, 1105, 704; HRMS
(EIS) calcd. for C30H27O4 [M+H]+: 451.1904, found 451.1910.
6-Ethyl-5,6-dihydrocyclopenta[b]thiophen-4-one (7r). oil; 1H
NMR (400 MHz, CDCl3) d ppm 7.31 (d, J = 5.2 Hz, 1H), 7.12
(d, J = 5.2 Hz, 1H), 3.43–3.37 (m, 1H), 3.14 (dd, J = 6.4, 18.4 Hz,
1H), 2.62 (dd, J = 2.8, 18.4 Hz, 1H), 1.83–1.66 (m, 2H), 1.05 (t,
J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 197.4, 174.4,
145.6, 130.6, 119.2, 48.1, 39.1, 29.2, 11.6; IR v (cm-1): 2966, 2930,
2877, 2253, 1738, 1705, 1374, 1246, 1047, 917, 733.
1-(2-tert-Butyldimethylsiloxyethyl)-1-methyl-1H-inden-3-yl ac-
etate (6s). oil; 1H NMR (400 MHz, CDCl3) d ppm 7.31–7.29 (m,
1H), 7.25–7.22 (m, 3H), 6.21 (s, 1H), 3.52–3.46 (m, 1H), 3.30–3.24
(m, 1H), 2.30 (s, 3H), 2.14–2.07 (m, 1H), 2.03–1.96 (m, 1H), 1.36
(s, 3H), 0.83 (s, 9H), -0.06 (s, 6H); 13C NMR (100 MHz, CDCl3) d
ppm 167.9, 150.1, 146.5, 137.6, 126.5, 126.2, 125.9, 121.4, 118.3,
60.1, 48.6, 41.2, 25.9, 24.1, 21.2, 18.2, -5.4; IR v (cm-1): 2956, 2930,
2858, 1773, 1205, 1109, 1090, 836, 776, 753; HRMS (EIS) calcd.
for C20H30NaO3Si [M+Na]+: 369.1856, found 369.1858.
3-Ethyl-3H-cyclopenta[a]naphthalen-1-yl benzoate (6o). oil;
1H NMR (400 MHz, CDCl3) d ppm 8.61 (d, J = 9.2 Hz, 1H),
8.37 (d, J = 7.6 Hz, 2H), 7.92 (d, J = 9.2 Hz, 1H), 7.81 (d, J =
8.4 Hz, 1H), 7.72 (d, J = 7.6 Hz, 1H), 7.64–7.61 (m, 3H), 7.51–
7.45(m, 2H), 6.68 (d, J = 2.0 Hz, 1H), 3.69–3.65 (m, 1H), 2.27–2.17
(m, 1H), 1.80–1.69 (m, 1H), 1.03 (t, J = 7.6 Hz, 3H); 13C NMR
(100 MHz, CDCl3) d ppm 164.3, 150.2, 144.9, 133.7, 133.4, 133.2,
130.1, 129.8, 128.8, 128.6, 127.3, 126.5, 126.0, 125.0, 123.4, 121.8,
121.5, 48.0, 24.0, 11.5; IR v (cm-1): 3056, 2963, 2928, 2870, 1742,
1251, 1179, 1132, 1058, 805, 705; HRMS (EIS) calcd. for C22H19O2
[M+H]+: 315.1380, found 315.1383.
1-(4-Methoxy-4-methylpentyl)-1-methyl-1H-inden-3-yl acetate
(6t). oil; 1H NMR (400 MHz, CDCl3) d ppm 7.30–7.27 (m, 1H),
7.26–7.23 (m, 3H), 6.21 (s, 1H), 3.09 (s, 3H), 2.32 (s, 3H), 1.72–1.65
(m, 1H), 1.42–1.24 (m, 4H), 1.41 (s, 3H), 1.05 (s, 6H); 13C NMR
(100 MHz, CDCl3) d ppm 168.0, 150.5, 146.7, 137.8, 126.4, 126.0,
125.9, 121.3, 118.2, 74.5, 50.2, 48.9, 40.2, 39.2, 24.9, 24.9, 23.6,
21.2, 19.5; IR v (cm-1): 2969, 2942, 1771, 1464, 1364, 1206, 1082,
755; HRMS (EIS) calcd. for C19H27O3 [M+H]+: 303.1955, found
303.1958.
(6u). oil; 1H NMR (400 MHz, CDCl3) d ppm 7.63 (d, J = 7.6 Hz,
1H), 7.33–7.21 (m, 3H), 6.59 (s, 1H), 2.58–2.51 (m, 2H), 2.46–2.39
(m, 2H), 2.33 (s, 3H), 2.31–2.17 (m, 2H); 13C NMR (100 MHz,
CDCl3) d ppm 168.1, 149.1, 146.6, 137.3, 126.5, 126.3, 124.1,
121.5, 117.7, 51.8, 29.7, 21.2, 17.1; IR v (cm-1): 2979, 2938, 1769,
1729, 1366, 1206, 1112, 756; HRMS (EIS) calcd. for C14H15O2
[M+H]+: 215.1067, found 215.1064.
3-Ethyl-2,3-dihydrocyclopenta[a]naphthalen-1-one (7o). oil; 1H
NMR (400 MHz, CDCl3) d ppm 9.17 (d, J = 8.4 Hz, 1H), 8.07
(d, J = 8.4 Hz, 1H), 7.90 (d, J = 8.0 Hz, 1H), 7.68 (dd, J = 8.4,
8.4 Hz, 1H), 7.57 (d, J = 8.0 Hz, 1H), 7.56 (dd, J = 8.4, 8.4 Hz,
1H), 3.44–3.38 (m, 1H), 2.97 (dd, J = 7.2, 18.8 Hz, 1H), 2.50 (dd,
J = 2.8, 18.8 Hz, 1H), 2.12–2.02 (m, 1H), 1.66–1.55 (m, 1H), 1.01
(t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) d ppm 207.0,
161.6, 135.7, 132.7, 130.8, 129.3, 128.9, 128.0, 126.6, 124.1, 122.8,
43.1, 39.5, 28.4, 11.5; IR v (cm-1): 3055, 2961, 2927, 2873, 1696,
1513, 1184, 1109, 825, 756; HRMS (EIS) calcd. for C15H14NaO
[M+Na]+: 233.0937, found 233.0940.
2,3,4,4a-Tetrahydro-1-(2-phenylethynyl)-1H-fluoren-9(9aH)-
1
one (9). oil; H NMR (400 MHz, CDCl3) d ppm 7.77 (d, J =
7-Ethyl-1,7-dihydro-1-methylcyclopenta[f ]indol-5-yl benzoate
(6p). oil; H NMR (400 MHz, CDCl3) d ppm 8.29 (d, J = 7.6
7.6 Hz, 1H), 7.58 (dd, J = 7.6, 7.6 Hz, 1H), 7.47–7.26 (m, 7H),
3.67–3.59 (m, 2H), 3.04 (dd, J = 2.4, 6.8 Hz, 1H), 2.28–2.23 (m,
1
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1H), 1.89–1.83 (m, 2H), 1.53–1.39 (m, 2H), 1.07–0.98 (m, 1H);
13C NMR (100 MHz, CDCl3) d ppm 204.2, 158.2, 134.9, 134.4,
131.6, 128.2, 127.7, 127.5, 124.9, 124.2, 123.8, 93.0, 81.2, 54.2,
37.5, 33.1, 28.2, 26.0, 19.8; IR v (cm-1): 3072, 2933, 2858, 2228,
1716, 1604, 758, 692; HRMS (EIS) calcd. for C21H19O [M+H]+:
287.1430, found 287.1425.
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Acknowledgements
This research was supported by the Fundamental Research
Funds for the Central Universities (lzujbky-2010-222), the MOST
(2010CB833200), the NSFC (20872054, 20732002) and program
111.
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7762 | Org. Biomol. Chem., 2011, 9, 7755–7762
This journal is
The Royal Society of Chemistry 2011
©