Baylis-Hillman acetates in carbocyclic synthesis: A convenient protocol for synthesis of densely substituted indenes

Article abstract of DOI:10.1016/j.tet.2012.12.069

A simple and facile strategy for synthesis of densely substituted indenes have been developed from Baylis-Hillman acetates in a two step protocol, that is, (1) via treatment with DABCO and then reaction with alkyl 3-oxobutanoates in the presence of K₂CO₃ (2) followed by the intramolecular Friedel-Crafts cyclization of the resulting keto-diesters using titanium tetrachloride.

Full text of DOI:10.1016/j.tet.2012.12.069

Tetrahedron 69 (2013) 1994e2003
Contents lists available at SciVerse ScienceDirect
Tetrahedron
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BayliseHillman acetates in carbocyclic synthesis: a convenient
protocol for synthesis of densely substituted indenes
*
Deevi Basavaiah , Bhavanam Sekhara Reddy, Harathi Lingam
School of Chemistry, University of Hyderabad, Central University (PO), Gachibowli, Hyderabad 500 046, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A simple and facile strategy for synthesis of densely substituted indenes have been developed from
BayliseHillman acetates in a two step protocol, that is, (1) via treatment with DABCO and then reaction
with alkyl 3-oxobutanoates in the presence of K2CO3 (2) followed by the intramolecular FriedeleCrafts
cyclization of the resulting keto-diesters using titanium tetrachloride.
Received 15 November 2012
Received in revised form 20 December 2012
Accepted 26 December 2012
Available online 3 January 2013
Ó 2013 Elsevier Ltd. All rights reserved.
Keywords:
BayliseHillman reaction
FriedeleCrafts reaction
Chemo selectivity
Indene derivatives
Keto-diesters
1. Introduction
functionalized molecules via an interesting atom economy coupling
of activated alkenes with electrophiles under the influence of
FriedeleCrafts reaction is one of the important and useful re-
actions for construction of carbonecarbon bonds and has been
extensively used in various organic synthetic processes.1 Intra-
molecular FriedeleCrafts reaction is one of the methods of choice
for synthesis of many carbocyclic and heterocyclic molecules.1,2
Indene/indane derivatives occupy an important place in the car-
bocyclic frameworks because of the presence of these moieties in
various natural products (1e3, Fig. 1)3 and bioactive compounds
(4e8, Fig. 1).4 Therefore, there has been increasing interest in the
development of simple and facile procedures for synthesis of
indene/indane derivatives via intramolecular FriedeleCrafts cycli-
zation strategies.5 In continuation of our interest in the synthesis of
a catalyst.7 Synthetic and medicinal chemists have used these
densely functionalized molecules, which are generally known as
the BayliseHillman adducts, in developing a number of useful
organic transformation protocols.7,8
carbocyclic compounds,6 we herein report
a facile two-step
methodology for obtaining highly substituted indene derivatives
starting from the BayliseHillman acetates using the intramolecular
FriedeleCrafts reaction as the key step.
2. Results and discussion
The BayliseHillman reaction has been and continues to attract
the attention of synthetic chemists as it provides densely
* Corresponding author. Tel.: þ91 040 23134812; fax: þ91 40 23012460; e-mail
address: dbsc@uohyd.ernet.in (D. Basavaiah).
Fig. 1. Natural products and bioactive molecules with ind(a)ene framework.
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.12.069

D. Basavaiah et al. / Tetrahedron 69 (2013) 1994e2003
1995
Several years ago we demonstrated the application of various
BayliseHillman adducts and their derivatives as substrates in a num-
ber of FriedeleCrafts reactions.9 On the basis of this experience it
occurred to us that it would be interesting to examine the intra-
molecular FriedeleCrafts (FeC) reaction of aromatic substrates (9)
containing one keto and two ester functionalities, as such study will
not only provide densely substituted indene or (and) indanone de-
rivatives but will also throw some light on the mechanism and che-
moselectivities of these intramolecular FriedeleCrafts (FeC)
reactions. Theoretically there is a possibility of formation of three
products, that is, (1) keto cyclization product (10) (2) free ester cycli-
Scheme 3. Reaction of 9a with titanium tetrachloride.
methylene-5-oxohexanoate (9b) as a substrate to examine the
intramolecular FriedeleCrafts reaction. The required keto-diester
9b was prepared from methyl 3-acetoxy-3-(3-methoxyphenyl)-2-
methylenepropanoate (13b) according to the reaction followed
for synthesis of keto-diester 9a. Thus the treatment of allyl acetate
13b (5 mmol) with DABCO (5 mmol) for 15 min at room tempera-
ture in THFeH2O (1:1) followed by reaction with methyl acetoa-
cetate (14a) (5.5 mmol), in the presence of K2CO3 (5.5 mmol) at
room temperature for 6 h provided 9b in 88% isolated yield
(dr z 1:1) (R¼3-OMe, Scheme 2).
zation product (11) (3) a,b-unsaturated ester cyclization product (12)
(Scheme 1). We also felt that such aromatic substrates (9) containing
one keto and two ester functionalities would easily be obtained from
the BayliseHillman acetates (13) via the reaction with suitable
nucleophiles as shown in retro-synthetic sequence (Scheme 1).
For initial studies we have treated 9b (1 mmol), with meth-
anesulfonic acid (2 mmol) in anhydrous dichloromethane (2 mL), at
room temperature for 1 h (addition at 0 ꢀC), which provided para
cyclization product 10b and ortho-cyclization product ortho-10b in
19% and 2% isolated yields, respectively (entry 1, Table 1) along with
65% un-reacted starting material 9b. With a view to confirm the
structures of molecules 10b and ortho-10b, we also obtained single
crystal for these compounds and established their structures by
X-ray data analysis (Figs. 2 and 3).12
Table 1
Optimization: intramolecular FriedeleCrafts cyclization of 9ba
MeO
Me
MeO
+
MeO
O
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
Me
MeO
acid
CO2Me
CO2H
16
+
CO2Me
10b
CH2Cl2
Scheme 1. Retro-synthetic strategy.
Me
Me
9b
ortho-10b
Accordingly we have first selected methyl 3-acetoxy-2-
methylene-3-phenylpropanoate (13a) and methyl acetoacetate
(14a) as reaction partners. Thus the treatment of 13a (10 mmol)
with DABCO (10 mmol) followed by the reaction with 14a
(11 mmol) in the presence of K2CO3 (11 mmol) in THFeH2O (1:1)
provided the desired keto-diester 9a in 75% isolated yield as
a mixture of diastereomers (1:1) (R¼H, Scheme 2).10
Entry
Condition(s)
Product yieldsb [%]
10b
ortho-10b
16
1
2
3
4
5
6
MeSO3H (2 equiv), 0 ꢀC to rt, 1 h
H2SO4 (2 equiv), 0 ꢀC to rt, 1 h
H2SO4 (1 equiv), 0 ꢀC to rt, 1 h
BF3.OEt2 (2 equiv), 0 ꢀC to rt, 1 h
TiCl4 (2 equiv), 0 ꢀC to rt, 1 h
TiCl4 (1 equiv), 0 ꢀC to rt, 4 h
19
46
61
60
76
61
2
10
10
7
20
8
d
35
7
d
d
d
Bold value indicates highest yield (optimized condition).
a
All reactions were carried out on a 1 mmol scale of keto-diester 9b with acid in
CH2Cl2 (2 mL).
b
Yields were based on keto-diester 9b.
Scheme 2. Synthesis of 9a and 9b.
We have then examined the intramolecular FriedeleCrafts re-
action of 9a under different conditions and our attempts were not
successful for obtaining any cyclized product (10a, 11a or 12a R¼H,
R0¼R00¼Me). We also noticed the formation of methyl (2Z)-2-
(chloromethyl)-3-phenylprop-2-enoate (15) in 18% yield along
with un-reacted starting material 9a (76% recovered yield) when
TiCl4 was used to perform the intramolecular FriedeleCrafts
reaction (Scheme 3).11
We have attributed the failure of intramolecular FriedeleCrafts
reaction of 9a to the less nucleophilicity of aromatic carbon(s) for
cyclization. At this stage, it occurred to us that electron donating
group on aromatic ring at appropriate position may enhance the
nucleophilicity of (para and/or ortho) carbon on the aromatic ring to
facilitate the intramolecular FriedeleCrafts cyclization. Accordingly
we selected methyl 4-methoxycarbonyl-3-(3-methoxyphenyl)-2-
Fig. 2. ORTEP diagram of compound 10b.

1996
D. Basavaiah et al. / Tetrahedron 69 (2013) 1994e2003
Table 3
Synthesis of highly substituted indene derivatives (10cej)a
O
CO2R4
CO2R5
CO2R5
CO2R4
Me
R1
R2
R1
R2
TiCl4 (2 eq.)
0 oC to rt
CH2Cl2, 0.5 h
R3
Me
10c-j
R3
R1 = R3 = OMe
9c-j
Entry
Keto-diester
R2
H
OMe
H
OMe
H
OMe
H
R4
R5
Product
Yieldb [%]
1
2
3
4
5
6
7
8
9c
9d
9e
9f
9g
9h
9i
Me
Me
Et
Me
Me
Me
Me
Et
Et
Et
Et
10cc
10d
10ec
10f
10g
10hc
10i
94
92
90
93
95
91
94
93
Fig. 3. ORTEP diagram of compound ortho-10b.
Et
Me
Me
Et
This reaction is indeed encouraging and clearly indicates that
ketone functionality takes part in FriedeleCrafts cyclization in
preference over ester function even in the presence of two ester
functionalities.13 With a view to increase the yield of the indene
derivatives in this reaction strategy, we have examined applica-
bility of various Bronsted and Lewis acids. In this direction we re-
alized that TiCl4 afforded better yields (entry 5, Table 1). Thus,
treatment of 9b (1 mmol) with TiCl4 (2 mmol, 2 M solution in DCM)
as a Lewis acid in dichloromethane (DCM) at room temperature for
1 h (addition at 0 ꢀC), provided 10b (para cyclization product) in
76% and ortho-10b (ortho-cyclization product) in 20% isolated yields
after usual work-up followed by column chromatography. When
H2SO4 was used as a reagent for cyclization, ester group at C-3
position underwent hydrolysis and provided 6-methoxy-1-(1-
methoxycarbonylethenyl)-3-methyl-1H-indene-2-carboxylic acid
(16) in 35% isolated yield along with expected indene esters 10b &
ortho-10b in 46 & 10% yields, respectively.
9j
OMe
Et
10j
a
All reactions were carried out on 1.0 mmol scale of keto-diesters (9cej) with
2 mmol of TiCl4 (1 mL, 2 M solution in CH2Cl2) in CH2Cl2 (2 mL) at room temperature
for 0.5 h.
b
Yields are based on keto-diesters.
Compound 10c, 10e, and 10h were further characterized by single crystal X-ray
c
data analysis (see SD).12
With a view to understand the generality of this reaction we
have prepared representative keto-diesters 9cej in 88e93% iso-
lated yields (dr z 1:1) via the reaction of selected BayliseHillman
acetates 13cef with DABCO followed by treatment with alkyl ace-
toacetates (14a/14b) under similar conditions as in the case of 13a
(or 13b) (Table 2). Subsequent treatment of these keto-diesters
9cej with TiCl4 at room temperature (addition at 0 ꢀC) provided
the resulting indene derivatives (10cej) in 91e95% isolated yields
(Table 3). Structures of the molecules 10c,10e, and 10h were further
confirmed by single crystal X-ray data analysis (See SD) [for ORTEP
diagram of 10h (see Fig. 4)].12
Fig. 4. ORTEP diagram of compound 10h.
After successful transformations of keto-diesters into highly
substituted indene derivatives we also investigated the orthoepara
selectivity in intramolecular FriedeleCrafts reactions. In this di-
rection we have prepared selected BayliseHillman acetates 13gek
and transformed them into keto-diesters (9keo) in 85e96% iso-
lated yields (in 1:1 diastereomeric ratio) (Table 4). Subsequent
Table 2
Synthesis of keto-diesters 9ceja
O
Table 4
CO2R5
CO2R5
CO2R4
Synthesis of keto-diesters (9b, 9keo)a
Me
OAc
R1
R2
COMe
14a-b
R1
R2
CO2R4
O
DABCO
THF-H2O (1:1)
rt, 15 min
CO2Me
CO2Me
K2CO3
rt, 6 h
OAc
Me
14a
R3
R1
R2
CO2R4
R3
13c-f
9c-j
R1
CO2R4
DABCO
COMe
14a: R5 = Me
R1 = R3 = OMe
88-93%
dr = 1:1
14b: R5 = Et
K2CO3
rt, 6 h
THF-H2O (1:1)
rt, 15 min
R2
dr = 1:1
9b, 9k-o
R3
13b, 13g-k
R3
R2 = R3 = H
Productb
Yieldc [%]
85-96%
Entry
Acetate
R2
H
OMe
H
OMe
H
OMe
H
OMe
R4
Keto-ester
1
2
3
4
5
6
7
8
13c
13d
13e
13f
13c
13d
13e
13f
Me
Me
Et
14a
14a
14a
14a
14b
14b
14b
14b
9c
9d
9e
9f
9g
9h
9i
93
88
94
89
91
93
92
90
Entry
Acetate
R1
R4
Productb
Yieldc [%]
1
2
3
4
5
6
13b
13g
13h
13i
13j
13k
OMe
OEt
OPr
OMe
OEt
Me
Me
Me
Et
Et
Et
9b
9k
9l
9m
9n
9o
88
92
96
85
86
91
Et
Me
Me
Et
Et
9j
OPr
a
a
All reactions were carried out on a 5 mmol scale of BayliseHillman acetates
All reactions were carried out on 5 mmol scale of BayliseHillman acetates (13b,
13gek) with 5 mmol of DABCO in THFeH2O (5þ5 mL) at rt for 15 min followed by
addition of 5.5 mmol of methyl acetoacetate (14a) under influence of K2CO3
(5.5 mmol) and stirred at room temperature for 6 h.
(13cef) with 5 mmol of DABCO in THFeH2O (5þ5 mL) at rt for 15 min followed by
addition of 5.5 mmol of keto ester (14a or 14b) under influence of K2CO3 (5.5 mmol)
and stirred at room temperature for 6 h.
b
b
The diastereomeric ratio was determined by the integration ratio of di-
The diastereomeric ratio was determined by the integration ratio of di-
astereomeric acetyl methyl protons.
astereomeric acetyl methyl protons.
c
c
Yields are based on BeH acetates.
Yields are based on BeH acetates.

D. Basavaiah et al. / Tetrahedron 69 (2013) 1994e2003
1997
treatment with TiCl4 under similar conditions as in the case of
3. Conclusion
10bej gave the para cyclized products in major amounts along with
ortho cyclized products in minor amounts (Table 5). The structures
of the molecules 10k, ortho-10k, and 10m were also established by
single crystal X-ray data analysis (see SD).12
In conclusion we have developed a convenient, operationally
simple synthesis of highly substituted indene derivatives from the
acetates of the BayliseHillman adducts in a two step protocol. This
study also throws some light on the competition between keto
cyclization and ester cyclization for intramolecular FriedeleCrafts
reaction in the substrates alkyl 4-alkoxycarbonyl-3-(alkox-
yphenyl)-2-methylene-5-oxohexanoates (9) containing two ester
groups and one keto group in a similar environment. In all these
reactions keto cyclization is preferred over ester cyclization even in
the presence of two ester groups. Thus this investigation has
demonstrated the importance of the BayliseHillman acetates for
designing probes to understanding the chemoselectivity13 profile
in intramolecular FriedeleCrafts reactions.
Table 5
Synthesis of indene derivatives (10b, 10keo, ortho-10b & ortho-10keo)a
O
CO2Me
CO2R4
CO2R4
Me
CO2Me
CO2R4
Me
TiCl4 (2 eq.)
R1
R1
R1
CO2Me
+
CH2Cl2
0 oC to rt, 1 h
Me
10b, 10k-o
9b,9k-o
ortho-10b, ortho-10k-o
Entry
Keto-diester
R1
R4
Product
Yieldb [%]
1
2
3
4
5
6
9b
9k
9l
9m
9n
9o
OMe
OEt
OPr
OMe
OEt
Me
Me
Me
Et
Et
Et
10b/ortho 10b
10kc/ortho-10kc
10l/ortho-10l
76/20
73/21
75/19
74/20
76/18
72/17
4. Experimental section
4.1. General remarks
10mc/ortho-10m
10n/ortho-10n
10o/ortho-10o
OPr
Melting points were recorded on a Superfit (India) capillary
melting point apparatus and are uncorrected. IR spectra were
recorded on a JASCO FT/IR-5300 spectrophotometer, solid samples
were recorded as KBr wafers and liquid samples as thin film be-
tween NaCl plates. 1H NMR (400 MHz) and 13C NMR (100 MHz)
spectra were recorded on a Bruker-AVANCE-400 spectrometer in
a
All reactions were carried out on a 1.0 mmol scale of keto-diesters (9b, 9keo)
with 2 mmol of TiCl4 (1 mL, 2 M solution in CH2Cl2) in CH2Cl2 (2 mL) at room
temperature for 1 h.
b
Yields are based on keto-diesters.
Compounds 10k, ortho-10k, and 10m were further characterized by single
c
crystal X-ray data (see SD).12
deuterochloroform (CDCl3) with tetramethylsilane (TMS,
d
¼0) as
Mechanism for the formation of highly substituted indene de-
rivatives from the keto-diesters is presented in Scheme 4, by taking
reaction between methyl 4-methoxycarbonyl-3-(3-methoxyphenyl)-
2-methylene-5-oxohexanoate (9b) and TiCl4 as a model case.13
Treatment of keto-diester with TiCl4 would generate titanium eno-
late intermediate (17) that might undergo further intramolecular
Michael/FriedeleCrafts reactions leading to the formation of the
indene derivatives, 10b & ortho-10b. It is believed that chelation
controlled titanium enolate species directs the mode of cyclization.
an internal standard for 1H NMR and chloroform-d middle peak of
the triplet (
d
¼77.10 ppm) as an internal standard for 13C NMR.
HRMS spectra were recorded on Bruker maXis ESI-TOF spectrom-
eter. The X-ray diffraction measurements were carried out at 298 K
on a Bruker SMART APEX CCD area detector system or Oxford
Diffraction Xcalibur Eos Gemini diffractometer equipped with
a graphite-mono-chromated Mo-K
of 0.71073 A.
a
radiation with the wavelength
ꢀ
4.2. Representative procedure
4.2.1. Synthesis of methyl 4-methoxycarbonyl-2-methylene-5-oxo-3-
phenylhexanoate (9a). To a stirred solution of methyl 3-acetoxy-2-
methylene-3-phenylpropanoate (13a) (10 mmol, 2.342 g) in
THFeH2O (20 mL, 1:1) was added DABCO (10 mmol, 1.121 g) at
room temperature and reaction mixture was stirred at the same
temperature for 15 min (until complete formation of salt monitored
by TLC). Methyl acetoacetate (14a) (11 mmol, 1.277 g) and K2CO3
(11 mmol, 1.520 g) were added and stirring was continued for
further 6 h at room temperature. Reaction mixture was quenched
by adding 2 N HCl (10 mL), and extracted with diethyl ether
(3ꢁ40 mL). Combined organic layer was dried over anhydrous
Na2SO4. Solvent was evaporated and crude product obtained was
purified by column chromatography (5% ethyl acetate in hexanes,
silica gel) to provide the title compound as a colorless viscous liquid
in 75% (2.180 g) isolated yield. This compound is known in the
literature. Spectral data of our compound are in agreement with the
known data.10
Reaction time: 15 minþ6 h; yield: 75%; Rf (20% EtOAc in hex-
anes) 0.41; colorless viscous liquid; IR (neat):
n 1743, 1716,
1630 cmꢂ1 1H NMR (400 MHz):
; d 1.96 & 2.27 (2s, 3H), 3.47, 3.67,
3.68 & 3.70 (4s, 6H), 4.38 & 4.41 (2d, 1H, J¼12.4 Hz), 4.71 & 4.73 (2d,
1H, J¼12.4 Hz), 5.70 & 5.76 (2s, 1H), 6.27 & 6.29 (2s, 1H), 7.17e7.32
(m, 5H); 13C NMR (100 MHz):
d 28.96, 30.55, 46.01, 46.13, 51.96,
52.01, 52.42, 52.65, 63.28, 64.38, 124.23, 125.16, 127.21, 127.30,
128.18, 128.39, 128.42, 128.60, 138.42, 138.77, 140.59, 141.23, 166.23,
166.38, 167.92, 167.99, 201.21, 201.33; HRMS (ESI) exact mass calcd
for C16H18O5Naþ (MþNa)þ: 313.1052, found: 313.1049.
Scheme 4. Plausible mechanism.

1998
D. Basavaiah et al. / Tetrahedron 69 (2013) 1994e2003
1H & 13C NMR spectra clearly indicate that it is a mixture of two
diastereomers almost in 1:1 ratio. The diastereomeric ratio was
determined by the integration ratio of diastereomeric acetyl methyl
protons.
(d, 1H, J¼2.0 Hz); 13C NMR (100 MHz):
d 14.02, 29.01, 30.81, 46.09,
46.23, 52.54, 52.65, 55.22, 60.97, 61.04, 63.21, 64.35, 98.93, 98.98,
106.35, 106.67, 124.24, 125.30, 140.66, 141.00, 141.30, 141.38, 160.61,
160.72,165.82,165.99,167.96, 201.28, 201.46; HRMS (ESI) exact mass
calcd for C19H24O7Naþ (MþNa)þ: 387.1420, found: 387.1417.
Methyl 4-methoxycarbonyl-3-(3-methoxyphenyl)-2-methylene-
5-oxohexanoate (9b) (dr z 1:1) was prepared in 88% isolated yield
via the treatment of allyl acetate 13b (5 mmol) with DABCO (5 mmol)
for 15 min at room temperature in THFeH2O (1:1) followed by re-
action with methyl acetoacetate (14a) (5.5 mmol), in the presence of
K2CO3 (5.5 mmol) at room temperature for 6 h. Similarly all the
remaining keto-diesters 9ceo were prepared in the similar manner
from the corresponding BH acetates (13cek) (5 mmol) and alkyl
acetoacetates (14a, b) (5.5 mmol). The compounds 9ceo were also
obtained as a mixture of two diastereomers almost in 1:1 ratio. The
diastereomeric ratio was determined by the integration ratio of di-
astereomeric acetyl methyl protons.
4.2.6. Ethyl 4-methoxycarbonyl-2-methylene-5-oxo-3-(3,4,5-
trimethoxyphenyl)hexanoate (9f). Reaction time: (15 minþ6 h);
yield: 89%; Rf (50% EtOAc in hexanes) 0.55; colorless viscous liquid;
IR (neat): n d 1.24 & 1.25
1745, 1716, 1630 cmꢂ1; 1H NMR (400 MHz):
(2t, 3H, J¼6.8 Hz), 2.00 & 2.27 (2s, 3H), 3.53 & 3.70 (2s, 3H), 3.79,
3.80 & 3.82 (3s, 9H), 4.07e4.26 (m, 2H), 4.38 (d, 1H, J¼12.4 Hz), 4.64
& 4.65 (2d, 1H, J¼12.0 Hz), 5.66 & 5.71 (2s, 1H), 6.27 & 6.29 (2s, 1H),
6.46 & 6.48 (2s, 2H); 13C NMR (100 MHz):
d 14.02, 28.97, 30.81,
46.38, 46.52, 52.55, 52.67, 56.01, 56.06, 60.73, 61.00, 61.06, 63.27,
64.39, 105.22, 105.50, 124.09, 125.15, 134.10, 134.50, 136.95, 137.05,
140.72, 141.34, 152.94, 153.09, 165.87, 166.04, 167.90, 168.00, 201.21,
201.54; HRMS (ESI) exact mass calcd for C20H26O8Naþ (MþNa)þ:
417.1525, found: 417.1528.
4.2.2. Methyl 4-methoxycarbonyl-3-(3-methoxyphenyl)-2-
methylene-5-oxohexanoate (9b). Reaction time: 15 minþ6 h;
yield: 88%; Rf (20% EtOAc in hexanes) 0.25; colorless viscous liquid;
IR (neat):
n
1745, 1724, 1630 cmꢂ1; 1H NMR (400 MHz):
d
1.99 & 2.27
4.2.7. Methyl 3-(3,5-dimethoxyphenyl)-4-ethoxycarbonyl-2-
methylene-5-oxohexanoate (9g). Reaction time: (15 minþ6 h);
yield: 91%; Rf (40% EtOAc in hexanes) 0.46; colorless solid, mp:
(2s, 3H), 3.50, 3.68, 3.69 & 3.70 (4s, 6H), 3.76 & 3.77 (2s, 3H), 4.38 &
4.39 (2d, 1H, J¼12.4 Hz), 4.68 & 4.71 (2d, 1H, J¼12.4 Hz), 5.69 & 5.74
(2s, 1H), 6.27 & 6.29 (2s, 1H), 6.71e6.88 (m, 3H), 7.15e7.22 (m, 1H);
59e61 ꢀC; IR (KBr):
n ;
1741, 1712, 1625 cmꢂ1 1H NMR (400 MHz):
13C NMR (100 MHz):
d
28.92, 30.51, 45.94, 46.06, 51.90, 51.96, 52.39,
d
1.04 & 1.22 (2t, 3H, J¼7.2 Hz), 2.03 & 2.26 (2s, 3H), 3.701 & 3.707
52.55, 55.04, 63.21, 64.31, 112.42, 114.08, 114.43, 120.41, 120.57,
124.33, 125.27, 129.35, 129.53, 140.08, 140.44, 140.55, 141.18, 159.50,
159.59, 166.20, 166.36, 167.86, 167.92, 201.07, 201.18; HRMS (ESI)
exact mass calcd for C17H20O6Naþ (MþNa)þ: 343.1158, found:
343.1153.
(2s, 3H), 3.75 (s, 6H), 3.98 & 4.15 (2q, 2H, J¼7.2 Hz), 4.34 & 4.35 (2d,
1H, J¼12.0 Hz), 4.65 (d, 1H, J¼12.4 Hz), 5.67 & 5.74 (2s, 1H),
6.23e6.35 (m, 2H), 6.37e6.46 (m, 2H); 13C NMR (100 MHz):
d 13.80,
14.00, 28.98, 30.70, 46.04, 46.09, 52.04, 52.10, 55.26, 61.55, 61.67,
63.48, 64.53, 98.95, 99.03, 106.51, 106.63, 124.59, 125.40, 140.60,
141.09, 141.14, 141.31, 160.63, 160.76, 166.34, 166.51, 167.47, 201.36,
201.42; HRMS (ESI) exact mass calcd for C19H24O7Naþ (MþNa)þ:
387.1420, found: 387.1418.
4.2.3. Methyl 3-(3,5-dimethoxyphenyl)-4-methoxycarbonyl-2-
methylene-5-oxohexanoate (9c). Reaction time: 15 minþ6 h;
yield: 93%; Rf (40% EtOAc in hexanes) 0.38; colorless solid; mp:
76e79 ꢀC; IR (KBr):
n
1747, 1714, 1630 cmꢂ1
;
1H NMR (400 MHz):
4.2.8. Methyl 4-ethoxycarbonyl-2-methylene-5-oxo-3-(3,4,5-
trimethoxyphenyl)hexanoate (9h). Reaction time: (15 minþ6 h);
yield: 93%; Rf (50% EtOAc in hexanes) 0.56; colorless low melting
d
2.02 & 2.26 (2s, 3H), 3.54, 3.69, 3.700 & 3.706 (4s, 6H), 3.750 &
3.753 (2s, 6H), 4.36 & 4.37 (2d, 1H, J¼12.4 Hz), 4.64 & 4.67 (2d, 1H,
J¼12.4 Hz), 5.67 & 5.72 (2s, 1H), 6.25e6.33 (m, 2H), 6.39 (d, 1H,
solid; mp: 48e50 ꢀC; IR (neat):
(400 MHz):
& 3.72 (2s, 3H), 3.79 & 3.82 (2s, 9H), 3.97 & 4.16 (2q, 2H, J¼7.2 Hz),
4.37 & 4.38 (2d, 1H, J¼12.4 Hz), 4.65 (d, 1H, J¼12.4 Hz), 5.69 & 5.75
(2s, 1H), 6.26 & 6.29 (2s, 1H), 6.47 & 6.49 (2s, 2H); 13C NMR
n ;
1747, 1718, 1630 cmꢂ1 1H NMR
1.02 & 1.23 (2t, 3H, J¼7.2 Hz), 2.02 & 2.27 (2s, 3H), 3.71
J¼2.4 Hz), 6. 41 (d,1H, J¼2.0 Hz), 13C NMR (100 MHz):
d
29.05, 30.81,
d
46.08, 46.21, 52.07, 52.13, 52.60, 52.71, 55.26, 63.23, 64.38, 98.95,
99.00, 106.34, 106.65, 124.55, 125.58, 140.43, 140.92, 141.08, 141.29,
160.65, 160.77, 166.31, 166.47, 167.94, 201.28, 201.41; HRMS (ESI)
exact mass calcd for C18H22O7Naþ (MþNa)þ: 373.1263, found:
373.1266.
(100 MHz):
d 13.82, 14.00, 28.94, 30.70, 46.36, 46.39, 52.08, 52.13,
56.07, 56.10, 60.76, 61.54, 61.70, 63.55, 64.55, 105.40, 105.48, 124.43,
125.24, 134.16, 134.44, 137.04, 140.64, 141.19, 152.96, 153.13, 166.37,
166.54, 167.40, 167.55, 201.30, 201.51; HRMS (ESI) exact mass calcd
for C20H26O8Naþ (MþNa)þ: 417.1525, found: 417.1527.
4.2.4. Methyl 4-methoxycarbonyl-2-methylene-5-oxo-3-(3,4,5-
trimethoxyphenyl)hexanoate (9d). Reaction time: (15 minþ6 h);
yield: 88%; Rf (50% EtOAc in hexanes) 0.48; colorless solid; mp:
64e65 ꢀC; IR (KBr):
n
1747, 1718, 1625 cmꢂ1
;
1H NMR (400 MHz):
4.2.9. Ethyl 3-(3,5-dimethoxyphenyl)-4-ethoxycarbonyl-2-
methylene-5-oxohexanoate (9i). Reaction time: (15 minþ6 h);
yield: 92%; Rf (40% EtOAc in hexanes) 0.37; colorless viscous liquid;
d
2.01 & 2.27 (2s, 3H), 3.53, 3.70, 3.71 & 3.72 (4s, 6H), 3.79 & 3.80 (2s,
3H), 3.824 & 3.827 (2s, 6H), 4.39 & 4.40 (2d, 1H, J¼12.4 Hz), 4.64 &
4.66 (2d, 1H, J¼12.4 Hz), 5.69 & 5.74 (2s, 1H), 6.27 & 6.29 (2s, 1H),
IR (neat):
n ; d [1.03 (t,
1741, 1716, 1625 cmꢂ1 1H NMR (400 MHz):
6.46 & 6.48 (2s, 2H); 13C NMR (100 MHz):
d
28.97, 30.75, 46.32,
J¼7.2 Hz) & 1.19e1.29 (m) (6H)], 2.02 & 2.27 (2s, 3H), 3.74 (s, 6H),
3.98 (q, 1H, J¼7.2 Hz), 4.07e4.22 (m, 3H), 4.33 & 4.35 (2d, 1H,
J¼12.0 Hz), 4.64 & 4.65 (2d, 1H, J¼12.0 Hz), 5.65 & 5.71 (2s, 1H),
6.24e6.33 (m, 2H), 6.40 & 6.42 (2d, 2H, J¼2.0 Hz); 13C NMR
46.46, 52.05, 52.10, 52.56, 52.68, 56.00, 56.05, 60.70, 63.23, 64.35,
105.16, 105.43, 124.36, 125.39, 133.96, 134.36, 136.93, 137.03, 140.45,
141.07, 152.94, 153.09, 166.30, 166.47, 167.87, 167.94, 201.17, 201.45;
HRMS (ESI) exact mass calcd for C19H24O8Naþ (MþNa)þ: 403.1369,
found: 403.1366.
(100 MHz):
d 13.76, 13.96, 14.02, 28.93, 30.70, 46.03, 46.10, 55.21,
60.93, 61.01, 61.49, 61.60, 63.44, 64.48, 98.91, 98.98, 106.50, 106.64,
124.26, 125.10, 140.80, 141.14, 141.36, 160.57, 160.70, 165.82, 166.00,
167.44, 167.48, 201.35, 201.46; HRMS (ESI) exact mass calcd for
C20H26O7Naþ (MþNa)þ: 401.1576, found: 401.1578.
4.2.5. Ethyl 3-(3,5-dimethoxyphenyl)-4-methoxycarbonyl-2-
methylene-5-oxohexanoate (9e). Reaction time: (15 minþ6 h);
yield: 94%; Rf (40% EtOAc in hexanes) 0.46; colorless viscous liquid; IR
(neat):
n
1745,1718,1625 cmꢂ1; 1H NMR (400 MHz):
d
1.23 & 1.24 (2t,
4.2.10. Ethyl 4-ethoxycarbonyl-2-methylene-5-oxo-3-(3,4,5-
trimethoxyphenyl)hexanoate (9j). Reaction time: (15 minþ6 h);
yield: 90%; Rf (50% EtOAc in hexanes) 0.51; colorless low melting
3H, J¼7.2 Hz), 2.01 & 2.26 (2s, 3H), 3.54 & 3.69 (2s, 3H), 3.74 & 3.75 (2s,
6H), 4.07e4.22 (m, 2H), 4.36 (d, 1H, J¼12.4 Hz), 4.60e4.70 (m, 1H),
5.65 & 5.70 (2s, 1H), 6.25e6.32 (m, 2H), 6.39 (d, 1H, J¼2.0 Hz), 6.41
solid; mp: 45e47 ꢀC; IR (neat):
n ;
1743, 1716, 1630 cmꢂ1 1H NMR

D. Basavaiah et al. / Tetrahedron 69 (2013) 1994e2003
1999
(400 MHz):
d
[1.01 (t, J¼6.8 Hz) & 1.19e1.31 (m) (6H)], 2.01 & 2.27
exact mass calcd for C19H24O6Naþ (MþNa)þ: 371.1471, found:
(2s, 3H), 3.79, 3.821 & 3.825 (3s, 9H), 3.97 (q, 1H, J¼6.8 Hz),
4.08e4.25 (m, 3H), 4.36 & 4.37 (2d, 1H, J¼12.4 Hz), 4.62 (d, 1H,
J¼12.4 Hz), 5.66 & 5.73 (2s, 1H), 6.26 & 6.29 (2s, 1H), 6.46 & 6.49 (2s,
371.1481.
4.2.15. Ethyl 4-methoxycarbonyl-2-methylene-5-oxo-3-(3-
propoxyphenyl)hexanoate (9o). Reaction time: (15 minþ6 h);
yield: 91%; Rf (20% EtOAc in hexanes) 0.50; colorless viscous liquid;
2H); 13C NMR (100 MHz):
d 13.75, 13.92, 14.00, 28.87, 30.68, 46.30,
46.35, 55.99, 60.67, 60.93, 61.00, 61.44, 61.60, 63.48, 64.47, 105.37,
105.46, 124.08, 124.89, 134.22, 134.51, 136.95, 140.83, 141.36, 152.87,
153.03, 165.84, 166.01, 167.34, 167.52, 201.23, 201.52; HRMS (ESI)
exact mass calcd for C21H28O8Naþ (MþNa)þ: 431.1682, found:
431.1684.
IR (neat): n d 1.02 (t, 3H,
1747, 1718, 1625 cmꢂ1; 1H NMR (400 MHz):
J¼7.6 Hz), 1.22 & 1.23 (2t, 3H, J¼7.2 Hz), 1.72e1.84 (m, 2H), 1.97 &
2.27 (2s, 3H), 3.50 & 3.70 (2s, 3H), 3.86 & 3.87 (2t, 2H, J¼6.4 Hz),
4.05e4.20 (m, 2H), 4.37 & 4.38 (2d, 1H, J¼12.0 Hz), 4.62e4.73 (m,
1H), 5.66 & 5.71 (2s, 1H), 6.27 & 6.29 (2s, 1H), 6.68e6.86 (m, 3H),
4.2.11. Methyl 3-(3-ethoxyphenyl)-4-methoxycarbonyl-2-methylene-
5-oxohexanoate (9k). Reaction time: (15 minþ6 h); yield: 92%; Rf
(20% EtOAc in hexanes) 0.35; colorless solid; mp: 64e66 ꢀC; IR
7.12e7.20 (m, 1H); 13C NMR (100 MHz):
d 10.49, 14.00, 22.53, 28.99,
30.75, 46.00, 46.13, 52.50, 52.66, 60.97, 61.03, 63.29, 64.44, 69.31,
113.10, 114.55, 114.88, 120.35, 120.55, 124.06, 125.11, 129.32, 129.51,
140.02, 140.39, 140.75, 141.40, 159.05, 159.15, 165.82, 165.98,
167.98, 168.03, 201.37, 201.54; HRMS (ESI) exact mass calcd for
C20H26O6Naþ (MþNa)þ: 385.1627, found: 385.1630.
(KBr):
n ; d 1.39 (t, 3H,
1753, 1716, 1631 cmꢂ1 1H NMR (400 MHz):
J¼7.2 Hz), 1.98 & 2.27 (2s, 3H), 3.50, 3.68, 3.694 & 3.699 (4s, 6H),
3.98 & 3.99 (2q, 2H, J¼6.8 Hz), 4.37 & 4.38 (2d, 1H, J¼12.4 Hz), 4.67
& 4.70 (2d, 1H, J¼12.4 Hz), 5.68 & 5.73 (2s, 1H), 6.27 & 6.29 (2s, 1H),
6.69e6.87 (m, 3H), 7.12e7.21 (m, 1H); 13C NMR (100 MHz):
d
14.80,
4.2.16. Methyl (2Z)-2-(chloromethyl)-3-phenylprop-2-enoate
29.02, 30.71, 46.05, 46.16, 52.06, 52.11, 52.55, 52.71, 63.36, 64.50,
113.15, 114.60, 114.94, 120.44, 120.61, 124.38, 125.40, 129.44, 129.63,
140.04, 140.41, 140.60, 141.24, 158.94, 159.05, 166.33, 166.49, 167.99,
168.06, 201.33, 201.44; HRMS (ESI) exact mass calcd for
C18H22O6Naþ (MþNa)þ: 357.1314, found: 357.1318.
(15). To a stirred solution of methyl 4-methoxycarbonyl-2-
methylene-5-oxo-3-phenylhexanoate (9a) (1 mmol, 0.290 g), in
anhydrous dichloromethane (2 mL), TiCl4 (2 mmol, 1 mL, 2 M so-
lution in dichloromethane) was added at 0 ꢀC. Reaction mixture
was stirred at room temperature for 12 h. Then the reaction mix-
ture was cooled to 0 ꢀC and quenched with water (2 mL) and
extracted with ethyl acetate (3ꢁ20 mL). Combined organic layer
was dried over anhydrous Na2SO4. Solvent was evaporated and the
residue thus obtained on purification by column chromatography
(5% ethyl acetate in hexanes, silica gel) provided methyl (2Z)-2-
(chloromethyl)-3-phenylprop-2-enoate (15) in (0.038 g) 18% iso-
lated yield as a colorless liquid along with un-reacted starting
material 9a in (0.220 g) 76% recovered yield. This compound (15) is
known in the literature. Spectral data of our compound are in
agreement with the known data.9d
4.2.12. Methyl 4-methoxycarbonyl-2-methylene-5-oxo-3-(3-
propoxyphenyl)hexanoate (9l). Reaction time: (15 minþ6 h);
yield: 96%; Rf (20% EtOAc in hexanes) 0.36; colorless viscous liquid;
IR (neat): n d 1.02 (t, 3H,
1741, 1722, 1635 cmꢂ1; 1H NMR (400 MHz):
J¼7.2 Hz), 1.73e1.84 (m, 2H), 1.98 & 2.27 (2s, 3H), 3.50, 3.68, 3.694 &
3.698 (4s, 6H), 3.86 & 3.87 (2t, 2H, J¼6.4 Hz), 4.37 & 4.39 (2d, 1H,
J¼12.4 Hz), 4.67 & 4.70 (2d, 1H, J¼12.4 Hz), 5.68 & 5.74 (2s, 1H), 6.27
& 6.29 (2s, 1H), 6.70e6.87 (m, 3H), 7.12e7.20 (m, 1H); 13C NMR
(100 MHz):
d 10.54, 22.57, 29.03, 30.74, 46.01, 46.14, 52.07, 52.12,
52.56, 52.73, 63.35, 64.50, 69.37, 113.17, 114.57, 114.88, 120.34,
120.52, 124.39, 125.41, 129.42, 129.60, 139.98, 140.35, 140.56, 141.21,
159.12, 159.22, 166.33, 166.48, 167.98, 168.05, 201.37, 201.49; HRMS
(ESI) exact mass calcd for C19H24O6Naþ (MþNa)þ: 371.1471, found:
371.1472.
Reaction time: 12 h; yield: 18%; Rf (10% EtOAc in hexanes) 0.44;
colorless liquid; IR (neat):
3.80 (s, 3H), 4.39 (s, 2H), 7.29e7.43 (m, 3H), 7.47 (d, 2H, J¼7.2 Hz),
7.80 (s, 1H); 13C NMR (100 MHz):
39.22, 52.56, 128.42, 128.95,
129.70, 129.80, 134.19, 143.89, 166.82.
n ;
1718, 1630 cmꢂ1 1H NMR (400 MHz):
d
d
4.2.13. Ethyl 4-methoxycarbonyl-3-(3-methoxyphenyl)-2-
methylene-5-oxohexanoate (9m). Reaction time: (15 minþ6 h);
yield: 85%; Rf (20% EtOAc in hexanes) 0.37; colorless viscous liquid;
4.2.17. Intramolecular FriedeleCrafts reaction of methyl 4-
methoxycarbonyl-3-(3-methoxyphenyl)-2-methylene-5-oxo-hex-
anoate (9b) with TiCl4. To
a stirred solution of methyl 4-
IR (neat):
n
1747, 1718, 1625 cmꢂ1; 1H NMR (400 MHz):
d
1.22 & 1.23
methoxycarbonyl-3-(3-methoxyphenyl)-2-methylene-5-oxo-hex-
anoate (9b) (1 mmol, 0.320 g), in anhydrous dichloromethane (2 mL),
TiCl4 (2 mmol,1 mL, 2 M solution in dichloromethane) was added at
0 ꢀC. After stirring at room temperature for 1 h, reaction mixture was
cooled to 0 ꢀC and quenched with water (2 mL) and extracted with
ethyl acetate (3ꢁ20 mL). Combined organic layer was dried over
anhydrous Na2SO4. Solvent was evaporated. Residue thus obtained
was purified by column chromatography (5% EtOAc in hexanes, silica
gel) to provide methyl 4-methoxy-1-(1-methoxycarbonylethenyl)-
3-methyl-1H-indene-2-carboxylate (ortho-10b) (minor product) and
methyl 6-methoxy-1-(1-methoxycarbonylethenyl)-3-methyl-1H-
indene-2-carboxylate (10b) (major product) in 20% (0.060 g) and 76%
(0.230 g) isolated yields, respectively. ortho-Cyclization product (or-
tho-10b) eluted first (less polar) and para cyclized product (10b)
eluted later (more polar).
(2t, 3H, J¼7.2 Hz), 1.98 & 2.27 (2s, 3H), 3.50 & 3.70 (2s, 3H), 3.76 &
3.77 (2s, 3H), 4.05e4.21 (m, 2H), 4.37 & 4.39 (2d, 1H, J¼12.4 Hz),
4.67 & 4.70 (2d, 1H, J¼12.0 Hz), 5.66 & 5.72 (2s, 1H), 6.27 & 6.29 (2s,
1H), 6.69e6.88 (m, 3H), 7.13e7.22 (m, 1H); 13C NMR (100 MHz):
d
14.00, 29.02, 30.74, 46.01, 46.13, 52.52, 52.69, 55.12, 60.98, 61.05,
63.27, 64.41, 112.45, 114.09, 114.46, 120.52, 120.70, 124.12, 125.15,
129.39, 129.56, 140.15, 140.51, 140.73, 141.37, 159.48, 159.58, 165.80,
165.96, 167.97, 168.01, 201.33, 201.48; HRMS (ESI) exact mass calcd
for C18H22O6Naþ (MþNa)þ: 357.1314, found: 357.1316.
4.2.14. Ethyl 3-(3-ethoxyphenyl)-4-methoxycarbonyl-2-methylene-
5-oxohexanoate (9n). Reaction time: (15 minþ6 h); yield: 86%; Rf
(20% EtOAc in hexanes) 0.38; colorless viscous liquid; IR (neat):
n
1743, 1718, 1630 cmꢂ1; 1H NMR (400 MHz):
d 1.221 & 1.229 (2t, 3H,
J¼7.2 Hz), 1.39 (t, 3H, J¼6.8 Hz), 1.97 & 2.27 (2s, 3H), 3.50 & 3.70 (2s,
3H), 3.94e4.04 (m, 2H), 4.07e4.21 (m, 2H), 4.36 & 4.37 (2d, 1H,
J¼12.4 Hz), 4.66 & 4.69 (2d,1H, J¼12.0 Hz), 5.66 & 5.71 (2s,1H), 6.27
& 6.29 (2s, 1H), 6.69e6.87 (m, 3H), 7.12e7.21 (m, 1H); 13C NMR
4.2.17.1. Methyl 6-methoxy-1-(1-methoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylate (10b). Reaction time: 1 h; yield:
76%; Rf (20% EtOAc in hexanes) 0.39; colorless solid; mp: 88e90 ꢀC;
(100 MHz):
d
13.99, 14.74, 28.99, 30.74, 45.98, 46.11, 52.49, 52.66,
IR (KBr): n d 2.54
1708, 1693, 1630, 1602 cmꢂ1; 1H NMR (400 MHz):
60.95, 61.01, 63.26, 64.42, 113.04, 114.52, 114.87, 120.43, 120.62,
124.03, 125.08, 129.34, 129.52, 140.04, 140.41, 140.74, 141.38, 158.84,
158.94, 165.79, 165.95, 167.96, 168.01, 201.33, 201.51; HRMS (ESI)
(d, 3H, J¼2.0 Hz), 3.74 (s, 3H), 3.80 (s, 3H), 3.81 (s, 3H), 4.85 (s, 1H),
5.39 (s, 1H), 6.11 (s, 1H), 6.89 (dd, 1H, J¼2.0 & 8.4 Hz), 6.93 (d, 1H,
J¼2.0 Hz), 7.37 (d,1H, J¼8.4 Hz); 13C NMR (100 MHz):
d 12.68, 50.88,

2000
D. Basavaiah et al. / Tetrahedron 69 (2013) 1994e2003
51.09, 52.16, 55.54, 109.39, 113.19, 122.28, 124.72, 130.62, 136.71,
139.09, 149.68, 152.91, 160.73, 165.66, 167.38; HRMS (ESI) exact
mass calcd for C17H18O5Naþ (MþNa)þ: 325.1052, found: 325.1054.
Crystal data for 10b: empirical formula, C17H18O5; formula
weight, 302.31; crystal color, colorless; habit, block; crystal di-
mensions, 0.52ꢁ0.40ꢁ0.28 mm3; crystal system, triclinic; lattice
HRMS (ESI) exact mass calcd for C16H16O5Naþ (MþNa)þ: 311.0895,
found: 311.0898.
4.2.19. Methyl 4,6-dimethoxy-1-(1-methoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylate (10c). Reaction time: 0.5 h; yield:
94%; Rf (20% EtOAc in hexanes) 0.34; colorless solid; mp:
ꢀ
ꢀ
type, primitive; lattice parameters, a¼9.6539(10) A, b¼9.7867(10) A,
130e132 ꢀC; IR (KBr):
(400 MHz):
n ;
1715, 1697, 1625, 1597 cmꢂ1 1H NMR
2.73 (d, 3H, J¼2.4 Hz), 3.71 (s, 3H), 3.80 (s, 3H), 3.81 (s,
ꢀ
c¼10.5569(11) A,
a
¼68.543(2),
b
¼64.2280(10),
g
¼61.3790(10);
d
3
V¼772.63(14) A ; space group, pꢂ1; Z¼2; Dcalcd¼1.299 g/cm3;
3H), 3.84 (s, 3H), 4.81 (s, 1H), 5.37 (s, 1H), 6.09 (s, 1H), 6.36 (d, 1H,
ꢀ
ꢀ
F000¼320;
l
(Mo-K
a
)¼0.71073 A; R(Iꢃ2s1)¼0.0473, wR2¼0.1276.
J¼1.6 Hz), 6.51 (s, 1H); 13C NMR (100 MHz):
d 15.64, 50.91, 51.15,
Detailed X-ray crystallographic data is available from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK (for compound 10b CCDC # 903059).
52.16, 55.30, 55.59, 97.63, 100.57, 124.52, 124.69, 128.80, 139.43,
151.69, 154.72,157.16,162.09,165.75, 167.54; HRMS (ESI) exact mass
calcd for C18H20O6Naþ (MþNa)þ: 355.1158, found: 355.1155.
Crystal data for 10c: empirical formula, C18H20O6; formula
weight, 332.34; crystal color, colorless; habit, block; crystal
4.2.17.2. Methyl 4-methoxy-1-(1-methoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylate (ortho-10b). Yield: 20%; Rf (20%
dimensions, 0.36ꢁ0.32ꢁ0.28 mm3; crystal system, monoclinic;
EtOAc in hexanes) 0.45; pale yellow solid; mp: 76e77 ꢀC; IR (KBr):
n
lattice type,
C
centered; lattice parameters, a¼19.345(3) A,
ꢀ
1720, 1703, 1620, 1599 cmꢂ1
;
1H NMR (400 MHz):
d
2.77 (d, 3H,
b¼9.5690(11) A, c¼21.222(4) A,
¼90.00,
b
¼122.10(2),
g
¼90.00;
ꢀ
ꢀ
a
3
ꢀ
J¼2.4 Hz), 3.73 (s, 3H), 3.80 (s, 3H), 3.87 (s, 3H), 4.86 (d,1H, J¼2.0 Hz
unresolved quartet), 5.38 (s, 1H), 6.09 (s, 1H), 6.80 (d, 1H, J¼8.0 Hz),
6.94 (d, 1H, J¼7.2 Hz), 7.22e7.30 (m, 1H); 13C NMR (100 MHz):
V¼3327.8(9) A ; space group, C 1 2/c 1; Z¼8; Dcalcd¼1.327 g/cm3;
ꢀ
F000¼1408;
l
(Mo-K
a
)¼0.71073 A; R(Iꢃ2s1)¼0.0472, wR2¼0.1304.
Detailed X-ray crystallographic data is available from the Cam-
bridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK (for compound 10c CCDC # 903060).
d
15.81, 51.08, 51.14, 52.15, 55.31, 109.52, 116.12, 124.59, 129.87,
130.88, 131.11, 139.15, 149.88, 154.33, 156.45, 165.79, 167.38; HRMS
(ESI) exact mass calcd for C17H18O5Naþ (MþNa)þ: 325.1052, found:
325.1047.
4.2.20. Methyl 1-(1-methoxycarbonylethenyl)-3-methyl-4,5,6-
trimethoxy-1H-indene-2-carboxylate (10d). Reaction time: 0.5 h;
yield: 92%; Rf (20% EtOAc in hexanes) 0.36; pale yellow solid; mp:
Crystal data for ortho-10b: empirical formula, C17H18O5; formula
weight, 302.31; crystal color, pale yellow; habit, block; crystal di-
mensions, 0.60ꢁ0.38ꢁ0.20 mm3; crystal system, triclinic; lattice
80e83 ꢀC; IR (KBr):
(400 MHz):
n ;
1710, 1699, 1625, 1599 cmꢂ1 1H NMR
2.73 (d, 3H, J¼2.4 Hz), 3.72 (s, 3H), 3.81 (s, 3H), 3.85
ꢀ
ꢀ
type, primitive; lattice parameters, a¼8.9453(10) A, b¼9.4121(11) A,
d
ꢀ
c¼10.5433(12) A,
a
¼106.120(2),
b
¼108.691(2),
g
¼103.365(2);
(s, 3H), 3.86 (s, 3H), 3.95 (s, 3H), 4.79 (d, 1H, J¼2.4 Hz, unresolved
V¼756.17(15) A ; space group, pꢂ1; Z¼2; Dcalcd¼1.328 g/cm3;
quartet), 5.38 (s, 1H), 6.10 (s, 1H), 6.70 (s, 1H); 13C NMR (100 MHz):
3
ꢀ
F000¼320;
l
(Mo-K
a
)¼0.71073 A; R(Iꢃ2s1)¼0.0456, wR2¼0.1249.
d 14.71, 50.97, 51.07, 52.11, 56.14, 60.87, 61.42, 103.12, 124.62, 128.59,
ꢀ
Detailed X-ray crystallographic data is available from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK (for compound ortho-10b CCDC #903062).
130.51, 139.25, 141.61, 144.47, 150.10, 153.73, 154.78, 165.49, 167.50;
HRMS (ESI) exact mass calcd for C19H22O7Naþ (MþNa)þ: 385.1263,
found: 385.1261.
4.2.18. Treatment of methyl 4-methoxycarbonyl-3-(3-
methoxyphenyl)-2-methylene-5-oxo-hexanoate (9b) with H2SO4. To
a stirred solution of methyl 4-methoxycarbonyl-3-(3-methoxy-
phenyl)-2-methylene-5-oxohexanoate (9b) (1 mmol, 0.320 g), in
anhydrous dichloromethane (2 mL), H2SO4 (2 mmol, 0.196 g) was
added at 0 ꢀC. After stirring at room temperature for 1 h, reaction
mixture was cooled to 0 ꢀC, quenched with water (2 mL) and
extracted with ethyl acetate (3ꢁ20 mL). Combined organic layer
was dried over anhydrous Na2SO4. Solvent was evaporated,
residue thus obtained was subjected to column chromatography
(5% EtOAc in hexanes, silica gel) to furnish methyl 4-methoxy-1-(1-
methoxycarbonylethenyl)-3-methyl-1H-indene-2-carboxylate
(ortho-10b) in 10%, (0.032 g), methyl 6-methoxy-1-(1-methoxy-
carbonylethenyl)-3-methyl-1H-indene-2-carboxylate (10b) in
46% (0.139 g) and 6-methoxy-1-(1-methoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylic acid (16) in 35% (0.100 g) iso-
lated yields.
4.2.21. Methyl 4,6-dimethoxy-1-(1-ethoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylate (10e). Reaction time: 0.5 h; yield:
90%; Rf (20% EtOAc in hexanes) 0.38; colorless solid; mp: 70e72 ꢀC;
IR (KBr): n d 1.28
1714, 1697, 1625, 1599 cmꢂ1; 1H NMR (400 MHz):
(t, 3H, J¼7.2 Hz), 2.72 (d, 3H, J¼2.4 Hz), 3.71 (s, 3H), 3.79 (s, 3H), 3.84
(s, 3H), 4.19e4.29 (m, 2H), 4.80 (m, 1H, unresolved quartet), 5.38 (s,
1H), 6.11 (s, 1H), 6.36 (d, 1H, J¼2.0 Hz), 6.52 (s, 1H); 13C NMR
(100 MHz):
d 14.11, 15.50, 50.75, 51.22, 55.18, 55.43, 60.79, 97.51,
100.42, 124.48, 128.70, 139.61, 151.59, 154.50, 157.05, 161.98, 165.63,
166.89; HRMS (ESI) exact mass calcd for C19H22O6Naþ (MþNa)þ:
369.1314, found: 369.1316.
Crystal data for 10e: empirical formula, C19H22O6; formula
weight, 346.37; crystal color, colorless; habit, block; crystal di-
mensions, 0.44ꢁ0.36ꢁ0.20 mm3; crystal system, monoclinic; lat-
ꢀ
tice type, primitive; lattice parameters, a¼12.2022(12) A,
ꢀ
ꢀ
a
b¼8.4746(9) A, c¼17.6407(18) A,
¼90.00,
b
¼102.136(2), ¼90.00;
g
V¼1783.4(3) A ; space group, P2(1)/c; Z¼4; Dcalcd¼1.290 g/cm3;
3
ꢀ
Spectral data (IR, 1H, 13C NMR) and mp of the compound 10b &
ortho-10b are in complete agreement with that prepared via the
treatment of 9b with methanesulfonic acid.
F000¼736;
l
(Mo-K
a
)¼0.71073 A; R(Iꢃ2s1)¼0.0616, wR2¼0.1635.
ꢀ
Detailed X-ray crystallographic data is available from the Cam-
bridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK (for compound 10e CCDC # 903061).
4.2.18.1. 6-Methoxy-1-(1-methoxycarbonylethenyl)-3-methyl-
1H-indene-2-carboxylic acid (16). Yield: 35%; Rf (50% EtOAc in
4.2.22. Methyl 1-(1-ethoxycarbonylethenyl)-3-methyl-4,5,6-
trimethoxy-1H-indene-2-carboxylate (10f). Reaction time: 0.5 h;
yield: 93%; Rf (20% EtOAc in hexanes) 0.31; colorless solid; mp:
hexanes) 0.30; pale yellow solid; mp: 176e178 ꢀC; IR (KBr):
n
2800e3200 (b), 1718, 1657, 1601 cmꢂ1; 1H NMR (400 MHz):
d 2.58
(d, 3H, J¼2.0 Hz), 3.80 (s, 3H), 3.82 (s, 3H), 4.85 (s, 1H), 5.47 (s, 1H),
6.15 (s, 1H), 6.90 (dd, 1H, J¼2.4 & 8.4 Hz), 6.94 (s, 1H, unresolved
doublet), 7.40 (d, 1H, J¼8.4 Hz), 12.08 (br s, 1H); 13C NMR
100e103 ꢀC; IR (KBr): 1706, 1615, 1599 cmꢂ1; 1H NMR (400 MHz):
n
d
1.28 (t, 3H, J¼7.2 Hz), 2.73 (d, 3H, J¼2.4 Hz), 3.73 (s, 3H), 3.85 (s,
3H), 3.86 (s, 3H), 3.95 (s, 3H), 4.23 (q, 2H, J¼7.2 Hz), 4.78 (s,1H), 5.41
(s, 1H), 6.13 (s, 1H), 6.71 (s, 1H); 13C NMR (100 MHz):
14.17, 14.71,
50.97, 51.30, 56.15, 60.90, 61.44, 103.11, 124.72, 128.66, 130.52,
(100 MHz):
d
12.96, 50.91, 52.18, 55.56, 109.36, 113.42, 122.66,
d
125.05, 129.95, 136.53, 138.73, 150.19, 155.72, 161.09, 167.28, 170.82;

D. Basavaiah et al. / Tetrahedron 69 (2013) 1994e2003
2001
139.47, 141.62, 144.47, 150.11, 153.66, 154.76, 165.54, 166.98; HRMS
(ESI) exact mass calcd for C20H24O7Naþ (MþNa)þ: 399.1420, found:
399.1422.
(9k) with TiCl4 in dichloromethane following the similar procedure
described for obtaining 10b and ortho-10b (from 9b), provided methyl
6-ethoxy-1-(1-methoxycarbonylethenyl)-3-methyl-1H-indene-2-
carboxylate (10k) (major product) and methyl 4-ethoxy-1-(1-
methoxycarbonylethenyl)-3-methyl-1H-indene-2-carboxylate
(ortho-10k) (minor product) in 73% and 21% isolated yields, re-
spectively, after purification through column chromatography (5%
EtOAc in hexanes, silica gel). ortho-Cyclization product (ortho-10k)
eluted first (less polar) and para cyclized product (10k) eluted later
(more polar).
4.2.23. Ethyl 4,6-dimethoxy-1-(1-methoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylate (10g). Reaction time: 0.5 h; yield:
95%; Rf (20% EtOAc in hexanes) 0.37; brick red color solid; mp:
74e76 ꢀC; IR (KBr):
(400 MHz):
(s, 3H), 3.84 (s, 3H), 4.07e4.28 (m, 2H), 4.81 (s, 1H), 5.36 (s, 1H), 6.10
(s, 1H), 6.36 (s, 1H), 6.49 (s, 1H); 13C NMR (100 MHz):
14.25, 15.52,
n ;
1728, 1678, 1620, 1599 cmꢂ1 1H NMR
d
1.25 (t, 3H, J¼6.8 Hz), 2.73 (s, 3H), 3.801 (s, 3H), 3.807
d
51.04, 52.07, 55.25, 55.54, 59.55, 97.57, 100.50, 124.61, 124.72,
129.18, 139.56, 151.76, 154.38, 157.08, 162.00, 165.24, 167.49; HRMS
(ESI) exact mass calcd for C19H22O6Naþ (MþNa)þ: 369.1314, found:
369.1317.
4.2.27.1. Methyl 6-ethoxy-1-(1-methoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylate (10k). Reaction time: 1 h; yield:
73%; Rf (20% EtOAc in hexanes) 0.49; colorless solid; mp: 77e79 ꢀC;
IR (KBr): n d 1.41
1724, 1685, 1620, 1602 cmꢂ1; 1H NMR (400 MHz):
(t, 3H, J¼7.2 Hz), 2.54 (d, 3H, J¼2.0 Hz), 3.74 (s, 3H), 3.80 (s, 3H), 4.03
(q, 2H, J¼7.2 Hz), 4.84 (s, 1H), 5.38 (s, 1H), 6.10 (s, 1H), 6.87 (dd, 1H,
J¼2.4 & 8.4 Hz), 6.92 (d, 1H, J¼1.2 Hz), 7.36 (d, 1H, J¼8.4 Hz); 13C
4.2.24. Ethyl 1-(1-methoxycarbonylethenyl)-3-methyl-4,5,6-
trimethoxy-1H-indene-2-carboxylate (10h). Reaction time: 0.5 h;
yield: 91%; Rf (20% EtOAc in hexanes) 0.39; colorless solid; mp:
NMR (100 MHz):
d 12.71, 14.85, 50.88, 51.11, 52.19, 63.77, 110.00,
72e74 ꢀC; IR (KBr):
(400 MHz):
n
1720, 1691, 1615, 1599 cmꢂ1
;
1H NMR
113.63, 122.30, 124.72, 130.53, 136.58, 139.13, 149.70, 153.03, 160.14,
165.73, 167.41; HRMS (ESI) exact mass calcd for C18H20O5Naþ
(MþNa)þ: 339.1208, found: 339.1217.
d
1.25 (t, 3H, J¼7.2 Hz), 2.73 (d, 3H, J¼2.4 Hz), 3.81 (s,
3H), 3.85 (s, 3H), 3.86 (s, 3H), 3.95 (s, 3H), 4.10e4.29 (m, 2H), 4.80
(d, 1H, J¼2.0 Hz, unresolved quartet), 5.37 (s, 1H), 6.11 (s, 1H), 6.69
Crystal data for 10k: empirical formula, C18H20O5; formula weight,
316.34; crystal color, pale yellow; habit, plate; crystal dimensions,
0.60ꢁ0.28ꢁ0.08mm3; crystalsystem, triclinic; lattice type, primitive;
(s,1H); 13C NMR (100 MHz):
d 14.19,14.63, 50.97, 52.05, 56.11, 59.68,
60.84, 61.39, 103.07, 124.70, 128.70, 130.90, 139.36, 141.57, 144.56,
150.02, 153.40, 154.70, 165.00, 167.46; HRMS (ESI) exact mass calcd
for C20H24O7Naþ (MþNa)þ: 399.1420, found: 399.1422.
ꢀ
ꢀ
ꢀ
lattice parameters, a¼5.7636(8) A, b¼9.3432(13) A, c¼15.310(2) A,
3
ꢀ
a
¼91.482(2),
b
¼92.853(3), ¼91.267(2); V¼822.9(2) A ; space group,
ꢀ
g
Crystal data for 10h: empirical formula, C20H24O7; formulaweight,
376.39; crystal color, colorless; habit, block; crystal dimensions,
0.52ꢁ0.40ꢁ0.28 mm3; crystal system, monoclinic; lattice type,
Pꢂ1; Z¼2; Dcalcd¼1.277 g/cm3; F000¼336;
l
(Mo-K
a
)¼0.71073 A;
R(Iꢃ2s1)¼0.0622, wR2¼0.1638. Detailed X-raycrystallographicdatais
available from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK (for compound 10k CCDC # 903071).
ꢀ
ꢀ
3
ꢀ
primitive; lattice parameters, a¼10.0264(11) A, b¼16.1212(17) A,
ꢀ
c¼12.7802(13) A,
a¼90.00,
b
¼107.732(2), ¼90.00; V¼1967.6(4) A ;
g
space group, P2(1)/c; Z¼4; Dcalcd¼1.271 g/cm3; F000¼800;
l
4.2.27.2. Methyl 4-ethoxy-1-(1-methoxycarbonylethenyl)-3-
(Mo-K
a
)¼0.71073 A; R(Iꢃ2s1)¼0.0852, wR2¼0.1666 Detailed X-ray
methyl-1H-indene-2-carboxylate (ortho-10k). Yield: 21%; Rf (20%
ꢀ
crystallographic data is available from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK (for
compound 10h CCDC # 903070).
EtOAc in hexanes) 0.56; pale yellow solid; mp: 75e76 ꢀC; IR (KBr):
n
1722, 1697, 1620, 1597 cmꢂ1 1H NMR (400 MHz):
; d 1.47 (t, 3H,
J¼6.8 Hz), 2.78 (d, 3H, J¼2.0 Hz), 3.73 (s, 3H), 3.80 (s, 3H), 4.09 (q,
2H, J¼6.8 Hz), 4.86 (s, 1H), 5.37 (s, 1H), 6.08 (s, 1H), 6.77 (d, 1H,
J¼8.4 Hz), 6.92 (d, 1H, J¼7.6 Hz), 7.19e7.26 (m, 1H); 13C NMR
4.2.25. Ethyl 4,6-dimethoxy-1-(1-ethoxycarbonylethenyl)-3-methyl-
1H-indene-2-carboxylate (10i). Reaction time: 0.5 h; yield: 94%; Rf
(20% EtOAc in hexanes) 0.41; brick red color solid; mp: 56e58 ꢀC;
(100 MHz): d 14.84, 15.80, 51.06, 52.15, 63.72, 110.26, 115.95, 124.53,
129.84,130.79,131.04, 139.20,149.88,154.54,155.84,165.82,167.40;
HRMS (ESI) exact mass calcd for C18H20O5Naþ (MþNa)þ: 339.1208,
found: 339.1204.
IR (KBr):
1.25 (t, 3H, J¼7.2 Hz), 1.28 (t, 3H, J¼7.2 Hz), 2.73 (d, 3H, J¼2.0 Hz),
3.79 (s, 3H), 3.84 (s, 3H), 4.08e4.30 (m, 4H), 4.80 (s, 1H), 5.38 (s, 1H),
6.12 (s, 1H), 6.36 (s, 1H), 6.50 (s, 1H); 13C NMR (100 MHz):
14.19,
n ;
1716, 1689, 1620, 1599 cmꢂ1 1H NMR (400 MHz):
d
Crystal data for ortho-10k: empirical formula, C18H20O5; for-
mula weight, 316.34; crystal color, pale yellow; habit, block;
crystal dimensions, 0.36ꢁ0.32ꢁ0.32 mm3; crystal system, tri-
d
14.28, 15.53, 51.27, 55.30, 55.56, 59.56, 60.86, 97.61, 100.48, 124.69,
129.17, 139.77, 151.78, 154.35, 157.10, 161.99, 165.30, 167.01; HRMS
(ESI) exact mass calcd for C20H24O6Naþ (MþNa)þ: 383.1471, found:
383.1473.
ꢀ
clinic; lattice type, primitive; lattice parameters, a¼6.965(4) A,
ꢀ
ꢀ
3
b¼7.746(4) A, c¼15.540(8) A,
a
¼78.010(9),
b
¼89.915(10),
ꢀ
g
¼80.114(9); V¼807.4(7) A ; space group, Pꢂ1; Z¼2;
ꢀ
Dcalcd¼1.301 g/cm3; F000¼336;
l
(Mo-K
a
)¼0.71073 A; R(Iꢃ2s1)¼
4.2.26. Ethyl 1-(1-ethoxycarbonylethenyl)-3-methyl-4,5,6-
trimethoxy-1H-indene-2-carboxylate (10j). Reaction time: 0.5 h;
yield: 93%; Rf (20% EtOAc in hexanes) 0.39; pale yellow solid; mp:
0.0499, wR2¼0.1372. Detailed X-ray crystallographic data is
available from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK (for compound ortho-10k
CCDC # 903073).
39e40 ꢀC; IR (KBr):
(400 MHz):
n ;
1709, 1697, 1616, 1599 cmꢂ1 1H NMR
1.26 (t, 3H, J¼7.2 Hz), 1.27 (t, 3H, J¼7.2 Hz), 2.73 (d, 3H,
d
J¼2.4 Hz), 3.85 (s, 3H), 3.86 (s, 3H), 3.95 (s, 3H), 4.10e4.31 (m, 4H),
4.77 (d, 1H, J¼2.4 Hz, unresolved quartet), 5.40 (s, 1H), 6.14 (d, 1H,
4.2.28. Treatment of methyl 4-methoxycarbonyl-2-methylene-5-oxo-
3-(3-propoxyphenyl)hexanoate (9l) with TiCl4. Reaction of methyl 4-
methoxycarbonyl-2-methylene-5-oxo-3-(3-propoxyphenyl)hex-
anoate (9l) with TiCl4 in dichloromethane following the similar
procedure described for obtaining 10b and ortho-10b (from 9b),
gave methyl 1-(1-methoxycarbonylethenyl)-3-methyl-6-propoxy-
1H-indene-2-carboxylate (10l) (major product) and methyl 1-(1-
methoxycarbonylethenyl)-3-methyl-4-propoxy-1H-indene-2-
carboxylate (ortho-10l) (minor product) in 75% and 19% isolated
yields, respectively, after purification through column chroma-
tography (5% EtOAc in hexanes, silica gel). ortho-Cyclization
J¼0.8 Hz), 6.70 (d, 1H, J¼0.4 Hz); 13C NMR (100 MHz):
d 14.10, 14.18,
14.59, 51.24, 56.08, 59.63, 60.79, 60.82, 61.37, 103.03, 124.73, 128.71,
130.82,139.53, 141.55,144.49,150.00,153.30,154.65, 165.01,166.91;
HRMS (ESI) exact mass calcd for C21H26O7Naþ (MþNa)þ: 413.1576,
found: 413.1574.
4.2.27. Reaction of methyl 3-(3-ethoxyphenyl)-4-methoxycarbonyl-2-
methylene-5-oxohexanoate (9k) with TiCl4. Treatment of methyl 3-
(3-ethoxyphenyl)-4-methoxycarbonyl-2-methylene-5-oxohexanoate

2002
D. Basavaiah et al. / Tetrahedron 69 (2013) 1994e2003
product (ortho-10l) eluted first (less polar) and para cyclized
product (10l) eluted later (more polar).
4.2.29.2. Methyl 1-(1-ethoxycarbonylethenyl)-4-methoxy-3-
methyl-1H-indene-2-carboxylate (ortho-10m). Yield: 20%; Rf
(20% EtOAc in hexanes) 0.58; pale yellow solid; mp: 44e46 ꢀC;
4.2.28.1. Methyl 1-(1-methoxycarbonylethenyl)-3-methyl-6-
propoxy-1H-indene-2-carboxylate (10l). Reaction time: 1 h; yield:
75%; Rf (20% EtOAc in hexanes) 0.44; pale yellow solid; mp:
IR (KBr): n ;
1716, 1697, 1625, 1601 cmꢂ1 1H NMR (400 MHz):
d
1.27 (t, 3H, J¼7.2 Hz), 2.76 (d, 3H, J¼2.4 Hz), 3.73 (s, 3H), 3.87 (s,
3H), 4.22 (q, 2H, J¼7.2 Hz), 4.85 (d, 1H, J¼2.0 Hz, unresolved quar-
tet), 5.39 (s, 1H), 6.11 (s, 1H), 6.80 (d, 1H, J¼8.4 Hz), 6.95 (d, 1H,
74e76 ꢀC; IR (KBr):
(400 MHz):
n ;
1722, 1685, 1620, 1602 cmꢂ1 1H NMR
1.03 (t, 3H, J¼7.2 Hz), 1.75e1.86 (m, 2H), 2.54 (d, 3H,
d
J¼7.6 Hz), 7.22e7.28 (m, 1H); 13C NMR (100 MHz):
d 14.15, 15.77,
J¼2.4 Hz), 3.74 (s, 3H), 3.80 (s, 3H), 3.92 (t, 2H, J¼6.4 Hz), 4.84 (d,1H,
J¼2.0 Hz, unresolved quartet), 5.38 (s, 1H), 6.10 (s, 1H), 6.88 (dd, 1H,
J¼2.4 & 8.4 Hz), 6.92 (d, 1H, J¼2.4 Hz), 7.36 (d, 1H, J¼8.4 Hz); 13C
51.03, 51.28, 55.30, 60.89, 109.47, 116.09, 124.59, 129.80, 130.93,
131.16, 139.37, 149.89, 154.19, 156.42, 165.79, 166.85; HRMS (ESI)
exact mass calcd for C18H20O5Naþ (MþNa)þ: 339.1208, found:
339.1205.
NMR (100 MHz):
d 10.54, 12.65, 22.59, 50.82, 51.04, 52.13, 69.73,
109.97, 113.59, 122.23, 124.65, 130.46, 136.47, 139.11, 149.64, 152.97,
160.31, 165.66, 167.37; HRMS (ESI) exact mass calcd for
C19H22O5Naþ (MþNa)þ: 353.1365, found: 353.1373.
4.2.30. Treatment of ethyl 3-(3-ethoxyphenyl)-4-methoxycarbonyl-
2-methylene-5-oxohexanoate (9n) with TiCl4. Reaction of ethyl 3-(3-
ethoxyphenyl)-4-methoxycarbonyl-2-methylene-5-oxohexanoate
(9n) with TiCl4 in dichloromethane following the similar procedure
described for obtaining 10b and ortho-10b (from 9b), provided
4.2.28.2. Methyl 1-(1-methoxycarbonylethenyl)-3-methyl-4-
propoxy-1H-indene-2-carboxylate (ortho-10l). Yield: 19%; Rf (20%
EtOAc in hexanes) 0.53; pale yellow solid; mp: 79e80 ꢀC; IR (KBr):
n
methyl
6-ethoxy-1-(1-ethoxycarbonylethenyl)-3-methyl-1H-in-
1718, 1697, 1610, 1597 cmꢂ1
;
1H NMR (400 MHz):
d
1.09 (t, 3H,
dene-2-carboxylate (10n) (major product) and methyl 4-ethoxy-1-
(1-ethoxycarbonylethenyl)-3-methyl-1H-indene-2-carboxylate
(ortho-10n) (minor product) in 76% and 18% isolated yields, re-
spectively, after purification through column chromatography (5%
EtOAc in hexanes, silica gel). ortho-Cyclization product (ortho-10n)
eluted first (less polar) and para cyclized product (10n) eluted later
(more polar).
J¼7.2 Hz),1.82e1.93 (m, 2H), 2.79 (d, 3H, J¼2.4 Hz), 3.73 (s, 3H), 3.80
(s, 3H), 3.99 (t, 2H, J¼6.0 Hz), 4.86 (d, 1H, J¼2.0 Hz, unresolved
quartet), 5.38 (s, 1H), 6.08 (s, 1H), 6.78 (d, 1H, J¼8.4 Hz), 6.92 (d, 1H,
J¼7.6 Hz), 7.19e7.26 (m, 1H); 13C NMR (100 MHz):
d 10.88, 15.83,
22.67, 51.00, 51.14, 52.09, 69.65, 110.16, 115.90, 124.46, 129.83,
130.83, 131.08, 139.27, 149.89, 154.40, 156.00, 165.78, 167.38; HRMS
(ESI) exact mass calcd for C19H22O5Naþ (MþNa)þ: 353.1365, found:
353.1367.
4.2.30.1. Methyl 6-ethoxy-1-(1-ethoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylate (10n). Reaction time: 1 h; yield:
76%; Rf (20% EtOAc in hexanes) 0.40; pale yellow solid; mp:
4.2.29. Treatment of ethyl 4-methoxycarbonyl-3-(3-methoxyphenyl)-
2-methylene-5-oxohexanoate (9m) with TiCl4. Reaction of ethyl 4-
methoxycarbonyl-3-(3-methoxyphenyl)-2-methylene-5-oxohex-
anoate (9m) with TiCl4 in dichloromethane following the similar
procedure described for obtaining 10b and ortho-10b (from 9b),
furnished methyl 1-(1-ethoxycarbonylethenyl)-6-methoxy-3-
methyl-1H-indene-2-carboxylate (10m) (major product) and
58e60 ꢀC; IR (KBr):
(400 MHz):
n ;
1718, 1685, 1615, 1604 cmꢂ1 1H NMR
1.26 (t, 3H, J¼7.2 Hz), 1.40 (t, 3H, J¼7.2 Hz),
d
2.53 (d, 3H, J¼2.0 Hz), 3.74 (s, 3H), 4.03 (q, 2H, J¼7.2 Hz), 4.18e4.27
(m, 2H), 4.82 (d, 1H, J¼2.0 Hz, unresolved quartet), 5.40 (s, 1H),
6.12 (s, 1H), 6.87 (dd, 1H, J¼2.0 & 8.4 Hz), 6.92 (d, 1H, J¼2.0 Hz),
7.36 (d, 1H, J¼8.4 Hz); 13C NMR (100 MHz):
d 12.62, 14.14,
methyl
1-(1-ethoxycarbonylethenyl)-4-methoxy-3-methyl-1H-
14.79, 51.01, 60.87, 63.69, 109.86, 113.64, 122.18, 124.65, 130.54,
136.58, 139.35, 149.66, 152.84, 160.08, 165.66, 166.83; HRMS (ESI)
exact mass calcd for C19H22O5Naþ (MþNa)þ: 353.1365, found:
353.1369.
indene-2-carboxylate (ortho-10m) (minor product) in 74% and 20%
isolated yields, respectively, after purification through column
chromatography (5% EtOAc in hexanes, silica gel). ortho-Cyclization
product (ortho-10m) eluted first (less polar) and para cyclized
product (10m) eluted later (more polar).
4.2.30.2. Methyl 4-ethoxy-1-(1-ethoxycarbonylethenyl)-3-
methyl-1H-indene-2-carboxylate (ortho-10n). Yield: 18%; Rf (20%
EtOAc in hexanes) 0.48; pale yellow solid; mp: 43e45 ꢀC; IR
4.2.29.1. Methyl 1-(1-ethoxycarbonylethenyl)-6-methoxy-3-
methyl-1H-indene-2-carboxylate (10m). Reaction time: 1 h; yield:
74%; Rf (20% EtOAc in hexanes) 0.50; pale yellow solid; mp:
(KBr):
n ; d 1.27
1712, 1630, 1597 cmꢂ1 1H NMR (400 MHz):
(t, 3H, J¼7.2 Hz), 1.46 (t, 3H, J¼6.8 Hz), 2.78 (d, 3H, J¼2.4 Hz),
3.73 (s, 3H), 4.09 (q, 2H, J¼7.2 Hz), 4.22 (q, 2H, J¼6.8 Hz,
unresolved two quartets), 4.84 (d, 1H, J¼2.0 Hz, unresolved
quartet), 5.39 (s, 1H), 6.10 (s, 1H), 6.77 (d, 1H, J¼8.4 Hz), 6.93 (d,
60e62 ꢀC; IR (KBr):
(400 MHz):
n ;
1709, 1695, 1620, 1602 cmꢂ1 1H NMR
1.27 (t, 3H, J¼7.2 Hz), 2.54 (d, 3H, J¼2.0 Hz), 3.74
d
(s, 3H), 3.81 (s, 3H), 4.18e4.28 (m, 2H), 4.83 (s, 1H), 5.41 (s, 1H), 6.13
(s, 1H), 6.88 (dd, 1H, J¼2.0 & 8.4 Hz), 6.93 (d, 1H, J¼1.6 Hz, not
properly resolved), 7.37 (d, 1H, J¼8.4 Hz); 13C NMR (100 MHz):
1H, J¼7.6 Hz), 7.19e7.26 (m, 1H); 13C NMR (100 MHz):
d 14.19,
14.85, 15.78, 51.04, 51.22, 60.91, 63.75, 110.25, 115.97, 124.53,
129.79, 130.89, 131.15, 139.46, 149.93, 154.41, 155.84, 165.85,
166.91; HRMS (ESI) exact mass calcd for C19H22O5Naþ (MþNa)þ:
353.1365, found: 353.1363.
d
12.60, 14.13, 51.00, 55.47, 60.87, 109.26, 113.19, 122.17, 124.65,
130.61, 136.71, 139.30, 149.64, 152.76, 160.69, 165.62, 166.81; HRMS
(ESI) exact mass calcd for C18H20O5Naþ (MþNa)þ: 339.1208, found:
339.1213.
Crystal data for 10m: empirical formula, C18H20O5; formula
weight, 316.34; crystal color, pale yellow; habit, block; crystal
dimensions, 0.40ꢁ0.36ꢁ0.32 mm3; crystal system, triclinic;
4.2.31. Reaction of ethyl 4-methoxycarbonyl-2-methylene-5-oxo-3-(3-
propoxyphenyl)hexanoate (9o) with TiCl4. Ethyl 4-methoxycarbonyl-
2-methylene-5-oxo-3-(3-propoxyphenyl)hexanoate (9o) on treat-
ment with TiCl4 in dichloromethane following the similar procedure
described for obtaining 10b and ortho-10b (from 9b), provided
methyl 1-(1-ethoxycarbonylethenyl)-3-methyl-6-propoxy-1H-
indene-2-carboxylate (10o) (major product) and methyl 1-(1-
ethoxycarbonylethenyl)-3-methyl-4-propoxy-1H-indene-2-
carboxylate (ortho-10o) (minor product) in 72% and 17% isolated
yields, respectively, after purification through column chromatog-
raphy (5% EtOAc in hexanes, silica gel). ortho-Cyclization product
ꢀ
lattice type, primitive; lattice parameters, a¼8.4689(13) A,
ꢀ
ꢀ
a
b¼9.7195(15) A, c¼10.6243(16) A,
¼81.293(3),
b
¼88.068(3),
3
ꢀ
g
¼72.963(3); V¼826.5(2) A ; space group, Pꢂ1; Z¼2;
ꢀ
Dcalcd¼1.271 g/cm3; F000¼336;
l
(Mo-K
a
)¼0.71073 A; R(Iꢃ2s1)¼
0.0500, wR2¼0.1288. Detailed X-ray crystallographic data is
available from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK (for compound 10m CCDC #
903072).

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eluted later (more polar).
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13a with 14a in the presence of DABCO (1.5 equiv) (see Ref: Singh, V.; Madapa,
S.; Batra, S. Synth. Commun. 2008, 38, 2113e2124). We have prepared this
compound 9a using a similar procedure with some modification.
4.2.31.1. Methyl 1-(1-ethoxycarbonylethenyl)-3-methyl-6-
propoxy-1H-indene-2-carboxylate (10o). Reaction time: 1 h; yield:
72%; Rf (20% EtOAc in hexanes) 0.43; pale yellow solid; mp:
41e43 ꢀC; IR (KBr):
(400 MHz):
n ;
1716, 1685, 1620, 1601 cmꢂ1 1H NMR
1.03 (t, 3H, J¼7.6 Hz), 1.26 (t, 3H, J¼7.2 Hz), 1.75e1.86
d
(m, 2H), 2.53 (d, 3H, J¼2.4 Hz), 3.74 (s, 3H), 3.92 (t, 2H, J¼6.8 Hz),
4.225 & 4.230 (2q, 2H, J¼7.2 Hz), 4.82 (d, 1H, J¼2.0 Hz, unresolved
quartet), 5.40 (s, 1H), 6.12 (s, 1H), 6.88 (dd, 1H, J¼2.4 & 8.4 Hz), 6.93
(d, 1H, J¼2.0 Hz, not properly resolved), 7.35 (d, 1H, J¼8.4 Hz); 13C
NMR (100 MHz):
d 10.53, 12.63, 14.15, 22.59, 51.02, 60.89, 69.75,
109.90, 113.68, 122.18, 124.68, 130.53, 136.56, 139.37, 149.67,
152.87, 160.31, 165.70, 166.88; HRMS (ESI) exact mass calcd for
C20H24O5Naþ (MþNa)þ: 367.1521, found: 367.1523.
4.2.31.2. Methyl 1-(1-ethoxycarbonylethenyl)-3-methyl-4-
propoxy-1H-indene-2-carboxylate (ortho-10o). Yield: 17%; Rf (20%
EtOAc in hexanes) 0.52; pale yellow solid; mp: 50e51 ꢀC; IR (KBr):
n
1714, 1695, 1615, 1599 cmꢂ1 1H NMR (400 MHz):
; d 1.09 (t, 3H,
J¼7.6 Hz), 1.27 (t, 3H, J¼7.2 Hz), 1.83e1.93 (m, 2H), 2.79 (d, 3H,
J¼2.4 Hz), 3.74 (s, 3H), 3.99 (t, 2H, J¼6.4 Hz), 4.230 & 4.233 (2q, 2H,
J¼7.2 Hz), 4.85 (d, 1H, J¼2.4 Hz, unresolved quartet), 5.40 (s, 1H),
6.11 (s, 1H), 6.78 (d, 1H, J¼8.0 Hz), 6.93 (d, 1H, J¼7.6 Hz), 7.20e7.26
(m, 1H); 13C NMR (100 MHz):
d 10.85, 14.11, 15.79, 22.62, 50.96,
51.22, 60.84, 69.57, 110.03, 115.82, 124.47, 129.75, 130.80, 131.06,
139.42, 149.85, 154.29, 155.93, 165.77, 166.84; HRMS (ESI) exact
mass calcd for C20H24O5Naþ (MþNa)þ: 367.1521, found: 367.1525.
Acknowledgements
We thank DST (New Delhi) for funding this project. B.S.R. thanks
CSIR and DST (New Delhi) for research fellowships. H.L. thanks CSIR
for her research fellowship. We thank UGC (New Delhi) for support
and for providing some instrumental facilities. We thank the Na-
tional Single-Crystal X-ray facility funded by DST. We also thank
Professor S. Pal, School of Chemistry, University of Hyderabad, for
helpful discussions regarding X-ray data analysis.
Supplementary data
Supplementary data related to this article can be found online at
http://dx.doi.org/10.1016/j.tet.2012.12.069.
References and notes
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Dekker: New York, NY, 1984; (c) Olah, G. A.; Krishnamurti, R.; Prakash, G. K. S.
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Chem. Rev. 2011, 111, PR181ePR214; (e) Sartori, G.; Maggi, R. FriedeleCrafts
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2. (a) Xu, Q.-L.; Dai, L.-X.; You, S.-L. Org. Lett. 2012, 14, 2579e2581; (b) Suzuki, Y.;
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M. Org. Lett. 2011, 13, 3000e3003; (d) Ying, W.; Barnes, C. L.; Harmata, M.
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E.; Indradas, B.; Snowden, R. L.; Sonnay, P. J. Org. Chem. 2009, 74, 5738e5741; (f)
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11. It has been well documented in the literature that treatment of BayliseHillman
acetates with Lewis acid like AlCl3 provides the corresponding allyl chlorides
(see Ref. 9d).
12. Detailed X-ray crystallographic data is available from the CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK for compounds 10b (CCDC # 903059), ortho-10b (CCDC
# 903062), 10c (CCDC # 903060), 10e (CCDC # 903061), 10h (CCDC # 903070),
10k (CCDC # 903071), ortho-10k (CCDC # 903073), and 10m (CCDC # 903072).
13. For recent references on chemoselective intramolecular FriedeleCrafts
reactions see 5a and 5d.