Metal-Free Domino One-Pot Decarboxylative Cyclization of Cinnamic Acid Esters: Synthesis of Functionalized Indanes

Article abstract of DOI:10.1021/acs.joc.6b02015

Trifluoroacetic acid promoted unprecedented domino reaction for the synthesis of diverse indanes starting from simple cinnamic acid esters is described. Their formation can be explained via acid triggered decarboxylation of cinnamic acid esters and subsequent inter/intramolecular cyclization. Overall process involves in the intramolecular cleavage of two σ-bonds (C-O and C-C) and inter/intramolecular construction of two/one C-C σ-bond(s). Significantly, this protocol was successful without the aid of any metal salts.

Full text of DOI:10.1021/acs.joc.6b02015

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Article
Metal-Free Domino One-pot Decarboxylative-Cyclization of
Cinnamic Acid Esters: Synthesis of Functionalized Indanes.
Alavala Gopi Krishna Reddy, and Gedu Satyanarayana
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.6b02015 • Publication Date (Web): 16 Nov 2016
Downloaded from http://pubs.acs.org on November 19, 2016
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The Journal of Organic Chemistry
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Metal-Free Domino One-pot Decarboxylative-Cyclization of
Cinnamic Acid Esters: Synthesis of Functionalized Indanes
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Alavala Gopi Krishna Reddy, and Gedu Satyanarayana*
Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi – 502 285, Sangareddy, Telangana,
INDIA
Phone: (040) 2301 6033; Fax: (040) 2301 6003 /32, E-mail: gvsatya@iith.ac.in
ABSTRACT: Trifluoroacetic acid promoted unprecedented domino reaction for the synthesis of diverse
indanes starting from simple cinnamic acid esters is described. Their formation can be explained via acid
triggered decarboxylation of cinnamic acid esters and subsequent inter-/intra-molecular cyclization.
Overall process involves in the intramolecular cleavage of two σ-bonds (C-O and C-C) and inter-/intra-
molecular construction of two/one C-C σ-bond(s). Significantly, this protocol was successful without the
aid of any metal salts.
Introduction
Decarboxylation reaction has emerged as a powerful tool in recent years for the synthesis of various
acyclic/polycyclic, natural/un-natural and biologically active molecules.1 The carboxylic acids and their
derivatives serve as potential synthetic precursors for this purpose.2 Among them, the benzoic acids have
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been applied for the synthesis of structurally diverse arenes.3 Olefinic carboxylic acids and their esters have
been used for the synthesis of olefins via decarboxylation.4 The well-known Krapcho decarboxylation
reaction comprises the loss of an alkoxycarbonyl group from α-carbon, but successful only when there is
another electron-withdrawing group connected to the same α-carbon (i.e. β-keto or β-ester etc.).5 While,
the functionalized benzoic acids have been used for the synthesis of biaryls, biaryl acetylenes and cyclic
systems via the decarboxylation followed by coupling with suitable partners, in the presence of a
transition-metal catalyst.6 The derivatives of malonic acids under decarboxylation furnishes amino acids,
ketals, ketones, naphthalene and quinolone derivatives.7 Most of these decarboxylation reactions are
assisted by expensive metal catalysts and reagents, whilst, the reports on metal-free decarboxylations are
limited.8 Very recently the research group of Kundu et al. established a metal-free decarboxylative
cyclization followed by ring expansion, for the construction of heterocycles.9 The cinnamic acid ester
derivatives, besides being biologically active, are also useful synthetic precursors for various cyclic systems
present in natural products and biologically active compounds.10
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Indane is an ubiquitous core in natural and un-natural compounds of biological importance.11 For example,
the indanes A and B are composites in ignition resistant thermoplastics.11a While, 1-methyl-1-phenyl-
indane C exhibits retinoic acid receptor (RAR) agonistic activity11b and the methyl-phenyl-indane is found
to be a part structure in anti-cancer natural product haouamine-A D11c,d (Figure 1).
Figure 1: Important compounds with indane skeleton.
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The Journal of Organic Chemistry
In continuation to our research interests in the development of one-pot synthetic protocols for the
efficient synthesis of various cyclic systems,12 herein we report an unprecedented trifluoroacetic acid
promoted one-pot13 decarboxylation followed by intermolecular domino carbo-cyclization for the
synthesis of indanes starting from readily available ethyl-3-phenylbut-2-enoates. Significantly, indane
products with a quaternary carbon atom were accomplished using this strategy. Notably, the present
protocol was found successful without the aid of any metal-catalysts. Moreover, this strategy was also
found amenable to carbon tethered cinnamic acid esters and enabled the synthesis of novel indane
products with a quaternary carbon atom. Unlike the Krapcho decarboxylation reaction, the present
method was successful without the support of a second electron-withdrawing group at the α-carbon. It is
worth noting that in our previous reports,12j-n for the synthesis of indanones or lactones, it was observed
that the reaction between cinnamic acid esters and arenes or phenols, exclusively proceeds through an
intermolecular Friedel-Crafts alkylation and intramolecular condensation as key steps, in the presence of
strong protic acid (TfOH)12g or Lewis acid (FeCl3),12e respectively. In addition, exclusive reaction of
cinnamic acid esters without external arenes with TfOH, gave indenones via intramolecular
condensation.12d Surprisingly, in the present study, the same esters upon treatment with trifluoroacetic
acid (i.e. CF3CO2H as reagent and also as medium), totally changed the chemoselectivity as well as the
reaction path and afforded the indanes.
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Results and Discussion
The synthetic study was initiated by choosing cinnamic acid ester 1a as model substrate. Thus, the ester 1a
ο
was reacted with trifluoroacetic acid [(TFA), as a reagent as well as medium] at 120 C for 12 h. To our
delight, the indane 2a was obtained as the sole product in an unprecedented manner (Table 1, entry 1). The
chemical structure of the product 2a was confirmed from its spectroscopic data. We believed that this
reaction might proceed via the formation of the corresponding carboxylic acid (i.e. β-methylcinnamic
acid). This carboxylic acid further would undergo acid mediated decarboxylation and generate the styrene
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intermediate, which in turn could undergo cyclodimerization to afford indane 2a. It is worth noting that
the possible formation of indenone through intramolecular Friedel-Crafts acylation was not observed. To
further improve the yield of 2a, the ester 1a was screened under different conditions (Table 1). Therefore,
1a was subjected with the acetic acid, however, led to the recovery of starting material 1a (Table 1, entry 2).
On the other hand, the reaction with 5 equivalents of TFA in DCE or CHCl3 or DCM, gave the hydrolyzed
cinnamic acid 2a, albeit in poor yields (Table 1, entries 3 to 5). Other solvents such as THF & DMF were
also found ineffective (Table 1, entries 6 & 7). While, the reaction was inconclusive with strong acids, such
as, AlCl3 and trifluoromethane sulfonic acid (TfOH), [i.e. neither the product 2a nor the starting material
1a was obtained (Table 1, entries 8 & 9)]. Also, the reaction with p-TSA and AuCl3 showed no progress
(Table 1, entries 10 & 11). Since the reaction was smooth in TFA, we presumed that the reduction of
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ο
temperature with prolonged reaction time might improve the yield. To our delight, the reaction at 80 C
for 24 h, furnished the indane 2a, in very good yield (Table 1, entry 12). Among all explored reaction
ο
conditions, the conditions with trifluoroacetic acid as solvent at 80 C for 24 h were best and gave the
indane 2a, in very good yield (Table 1, entry 12).
Table 1: Optimization studies for one-pot decarboxylative cyclodimerization to give indane 2a.a
Entry
Acid
Solvent
(mL)
Temp Time Yield Yield
(oC)
(h)
2a
3a
(equiv)
(%)b
(%)b
c
1
-
TFA (3.0)
AcOH (3.0)
DCE (1.0)
120
120
80
12
24
24
62
-
-
c
-
d
-
2
3
TFA
(5 equiv)
TFA
-
38
32
4
CHCl3 (1.0)
80
24
-
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The Journal of Organic Chemistry
(5 equiv)
TFA
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2
3
4
5
5
DCM (1.0)
THF (1.0)
DMF (1.0)
DCE (1.0)
40
70
80
80
48
24
40
24
-
-
-
-
20
(5 equiv)
TFA
d
-
6
6
7
8
9
(5 equiv)
TFA
d
-
10
7
11
12
13
(5 equiv)
AlCl3
e
-
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8
(3 equiv)
c
e
9
-
TfOH (1.0)
DCE (0.5)
80
80
24
24
-
-
-
d
10
p-TSA
(1 equiv)
AuCl3
-
d
11
DCE (1.0)
TFA (3)
80
80
24
24
-
-
(5 mol%)
c
-
12
86
-
aUnless otherwise mentioned, all reactions were carried out by using 100 mg (0.53 mmol) of cinnamic acid ester 1a. Isolated
b
yields of chromatographically pure products. Acid was used as the solvent. dNo progress of the reaction, only the starting
c
material was recovered. eReaction is not clean, no significant spot on TLC is seen.
In order to check the scope and generality of the method, the optimized conditions (Table 1, entry 12) were
applied on other cinnamic acid esters 1a-l. Gratifyingly, the protocol was amenable to those esters 1a-l with
various functional groups on the aromatic ring and furnished the indanes 2a-l (Table 2). Significantly, the
reaction was also compatible with electron donating meta-methoxy group on the aromatic ring of the
cinnamic acid ester 1g and furnished the indane 2g along with minor regio-isomer (Table 2). The
formation of minor regio-isomer can be justified due to the cyclization at the ortho-carbon to the methoxy
group (Table 2). Moreover, the reaction was also performed at low temperatures, however, it showed no
significant improvement of para selectivity towards the cyclization to give exclusively 2g. On the other
hand, to our delight, the reaction with para-methoxy cinnamic acid ester 1i, as anticipated, furnished the
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indane 2h as sole product (Table 2), the dimethyl ether of composite in ignition resistant thermoplastics
(see; compound B, Figure 1). It is worth mentioning that the electron withdrawing groups on the aromatic
ring retarded the reaction. Hence, no product 2i was formed with para-nitro cinnamic acid ester 2i, which
is usual in Friedel-Crafts alkylations (Table 2). Notably, the reaction was also quite successful with
benzophenone derived cinnamic acid ester 1l as well and gave the triphenyl indane 2l, in excellent yield
(Table 2).
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Table 2: Scope of domino decarboxylation and dimerization for indanes 2.a,b,c
Me
COOEt
R2
R2
R1
TFA
80 °C
12 to 48 h
R1
R2
R1
1
2
R2 = Me, Ph
Me
Me
Me
Me
Me
Me
F
Cl
Me
2a
Me
Me
2c
F
Cl
2b
(86%)
(91%)
(89%)
Me
Me
Me
Me
Me
Me
Me
Me
Br
Me
Me
Me
2e
Me
Br
Me
2d
2f
(74%)
(96%)
Me
(76%)
Me
Me
Me
Me
Me
MeO
O2N
MeO
Me
Me
Me
OMe
NO2
dOMe
e
2g
2h
2i
(---)
(86%, 3:1)
(52%)
dimethyl ether of composite
in ignition resistant thermoplastics (B)
Me
Me
Me
Me
Me
Et
Me
Me
Et
2j (65%)
2k (68%)
2l (92%)
a
Reaction conditions: cinnamic acid esters 1a-l (0.53 mmol) in trifluoroacetic acid (3.0 mL) at 80 °C for 12 to 48 h. bYields in the
c
parentheses are isolated yields of chromatographically pure products 2a-l. All the reactions have been carried out on E-isomer
d
of 1. Only the major product of the regio-is0meric mixture is shown, ratio in the parenthesis indicates the ratio of two regio-
isomers. eNo progress of the reaction.
Since the indanes 2 contain no double bond, we presumed that the geometry of the double bond of the
synthetic precursors (i.e. cinnamic acid esters) 1 is insignificant. Thus, the Z-isomer 1’ must also produce
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The Journal of Organic Chemistry
the same indane product 2. Therefore, the Z-isomer 1a’ was subjected, under standard conditions. As
anticipated, the indane 2a (Scheme 1) was formed as the sole product in comparable yield to that obtained
from 1a (i.e. the formation of 2a from 1a; Table 2). It is worth mentioning that the possibility for the
formation of indenone 4a, was not observed, in spite of favorable Z-geometry of the double bond of 1a’ for
intramolecular condensation12d (i.e. Friedel-Crafts acylation) (Scheme 1).
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Scheme 1: Selective formation of indane 2a from the Z-isomer 1a’.
When the reaction was carried out with 3-aryl-3-ethyl prop-2-enoate 5, as expected, resulted a complex
mixture of indanes 6 and 6’. This can be explained via the formation of styrenes 5a & 5b with terminal and
internal double bonds and subsequent homo and hetero cyclodimerization (Scheme 2). On the similar
grounds, it was presumed that tetrasubstituted acrylate, for example, ethyl α,β-dimethyl-beta-
phenylacrylate, would also proceed through the formation of same mixture of alkene intermediates (5a &
5b) that are feasible from the acrylate 5. Hence, it would lead to the same complex mixture of indanes (6 &
6’) that were obtained from 5.
Scheme 2: Formation of mixture of indanes 6 and 6’ from 5.
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Since, the cinnamic acid 3a was formed as the by-product during the course of optimization; we
speculated that the acid 3a may be one of the feasible intermediates. Therefore, the cinnamic acid 3a was
also reacted with TFA, under standard conditions. Gratifyingly, as expected, afforded the indane 2a, in very
good yield (Scheme 3). Thus, it reveals that the acid 3 would be one of the reaction intermediates of this
process. Since, the products 2 have no carbonyl group; we presumed that certainly decarboxylation could
have taken place from the acid 3a to give styrene as the subsequent intermediate. To further confirm this,
the reaction was performed with α-methyl styrene 11a, under established condition. To our delight, as
anticipated, it furnished the indane 2a, in excellent yield (Scheme 3). With these control experiments, it is
confirmed that the acid 3a and styrene 11a are consecutive intermediates of this strategy.
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Scheme 3: Control experiments that proves the intermediacy of the acid 3a and the styrene 11a to give indane 2a.
Moreover the reaction of ethyl (2E)-3,4-dihydronaphthalen-1(2H)-ylideneacetate 7, under established
conditions, gave the α-methyl naphthalene 8 (Scheme 4). With this outcome, we can ascertain sequential
steps for the conversion of 7 to 8, such as: i) formation of acid 7a; ii) decarboxylation to give olefin 7b and
iii) aromatization to give 8. In addition, in this case, the intramolecular aromatization would be the
driving force that could override the intermolecular cyclodimerization.
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Scheme 4: Formation of α-methyl naphthalene 8 from the ester 7.
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After the effective construction of indanes 2a‒i, to further demonstrate the applicability of the method, we
envisioned that cinnamic acid ester 9 with an appropriate carbon tether would furnish the indane 10
(Scheme 5).
Scheme 5: Possibility for the intramolecular cyclization to 10.
The requisite carbon tethered cinnamic acid esters 9 were prepared from simple benzaldehydes 13 by
using stepꢀwise Grignard/Barbier reaction, JefferyꢀHeck and WittigꢀHornerꢀWadsworthꢀEmmons
protocol. Notably, each step of the sequence progressed smoothly and afforded the desired cinnamates
9, as depicted in Table 3.
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Table 3: Schematic results towards the synthesis of cinnamates 9 starting from simple benzaldehydes 13.a
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The Journal of Organic Chemistry
I
R2
COOEt
n
1
2
3
4
5
OH
OH
O
CHO
Pd(OAc)2, Et3N
MgBr
THF
NaH, TEPA
R1
R1
R1
R2
R1
R2
n
THF
0 to reflux, 12h
dry CH3CN
80 °C, 24 h
0 to rt, 2h
n = 1,2
n = 1,2
13
14
15
9
COOEt
O
6
CHO
7
8
9
10
13a
14a (86%)
15a (84%)
9a (88%)
COOEt
OH
O
CHO
11
13b
14b
15b
9b
(87%)
Cl
Cl
(83%)
Cl
(79%)
Cl
12
13
14
COOEt
OH
O
CHO
Br
13c
Br
Et
14c (88%)
Br
Et
15c (69%)
Br
Et
9c (90%)
15
COOEt
16
17
18
OH
O
CHO
Et
13d
14d (91%)
15d (86%)
9d (87%)
19
COOEt
20
21
22
23
24
25
OH
O
CHO
Me
Me
Me
Me
13a
14a
15e
9e
9f
(86%)
(83%)
(82%)
(80%)
(88%)
COOEt
OH
O
CHO
26
Cl
Cl
Cl
Cl
13b
14b
15f
(86%)
27
28
29
COOEt
OH
O
CHO
30
Br
Br
Et
Br
Et
Me
Me
Br
Et
Me
13c
14c
15g
9g
(88%)
(66%)
(91%)
31
32
33
COOEt
OH
O
CHO
Et
Me
13d
14d (91%)
15h (83%)
9h (88%)
34
COOEt
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
OH
O
CHO
OMe
OMe
13a
14a (86%)
15i (86%)
9i (88%)
COOEt
OH
O
CHO
OMe
OMe
OMe
OMe
13a
14a (86%)
15j (82%)
9j (80%)
COOEt
OH
O
CHO
13a
14a (86%)
15k (81%)
NO2
9k (42%)
NO2
COOEt
OH
O
CHO
13a
14e (78%)a
15l (64%)
9l (80%)
aThe yields in the parenthesis are isolated yields of chromatographically pure products. The homo allylic
b
51
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59
60
alcohol 14e was prepared by using zinc mediated Barbier reaction.14
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Finally, these cinnamic acid esters 9a-j were treated with TFA, under established conditions. Gratifyingly,
this intramolecular carbocyclization variant was also found amenable and furnished the novel analogous
indanes 10a-j with a quaternary carbon atom (Table 4). Significantly, the reaction showed good substrate
scope. Also, compatible with alkyl, bromo and chloro substituents on the carbon tethered aromatic ring.
Notably, the reaction was also amenable with electron releasing methoxy groups on the tethered aromatic
moiety (entries 1oi and 10j). In a similar context, as noticed above (Table 2, for compound 2i), electron
withdrawing nitro group retarded the reaction (Table 4, for compound 10k). Gratifyingly, the reaction was
also amenable with the homologated ester 9l and furnished the tetralin derivative 10l (Table 4). It is worth
mentioning that the product 10l accompanied the minor indane as an inseparable mixture. This may be
due to the isomerization of the terminal double bond into internal one and subsequent internal
cyclization. However, after careful column chromatography and by collecting of first few fractions,
relatively pure NMR spectra were obtained for 10l. Gratifyingly, the product C/10a is a RAR transactivator.
Also, interestingly, the compound 10l is a methyl analogue of another RAR agonist 1-phenyl tetralin.
1
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58
59
60
Table 4: Scope of intramolecular domino decarboxylation and cyclization to cyclic products 10.a,b
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COOEt
R1
Me
1
2
TFA
R2
R1
R2
n
80 °C
12 to 24 h
n
3
4
5
6
7
8
9
9
10
n = 1,2
Cl
Br
Me
Me
Me
c
c
d
C/10a
10b
10c
(82%)
(79%)
(86%)
Me
transactivator of RAR
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Et
Cl
Me
Me
Me
Me
c
c
c
10d
10e
10f
(81%)
(74%)
(79%)
Br
Et
Me
Me
Me
Me
Me
MeO
d
c
c,e
10g
10h
10i
(83%)
(74%)
Me
(64%, 5:1)
Me
Me
MeO
MeO
O2N
c
c,f
c
10j
10k
10l
(72%)
(---%)
(52%)
Reaction conditions: acinnamic acid esters 9a‒k (0.53 mmol) in trifluoroacetic acid (3.0 mL) at 80 °C for 12 to 48 h. bYields in the
c
d
parentheses are isolated yields of chromatographically pure products 10a‒k. Reaction was carried out on E-isomer. Reaction
e
was conducted on Z-isomer. Only the major product 10i of the regio-isomeric mixture is shown, ratio in the parenthesis
indicates the ratio of two regio-isomers. fNo progress of the reaction.
It is important to note that the β,β-disubstitution (alkyl/aryl or aryl/aryl) pattern on the cinnamic acid
esters is vital to drive the reaction to give indanes, because when simple ethyl cinnamate 1l (eq. 1), α-aryl
methyl acrylate 16 (eq. 2) and a 1:1 mixture of α-benzyl methyl acrylate 17 and α-methyl-β-aryl methyl
acrylate 17’ (eq. 3) were subjected, under the established conditions, it showed no progress and led to the
recovery of the starting materials (Scheme 6). This can be justified based on the fact that these systems
(eq. 1-3) are devoid of second β-alkyl/aryl groups, hence, may not be easy to facilitate formation of β-
carbocation/double bond isomerization and subsequent decarboxylation step.
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Scheme 6: Scope of the reaction with cinnamates 1l, 16 and 17.
Based on the above control experiments, the overall reaction mechanism for this domino process is shown
in Scheme 7. Initially, the ester 1a would transform into the acid 3a through acid mediated hydrolysis of
ester 1a. Acid promoted decarboxylation of 3a generates the styrene 11a. Finally, the styrene 11a undergoes
cyclodimerization via activation of olefin by the acid and affords the indane 2a (Scheme 7). A similar sort
of mechanism would be proposed for the formation of indane 10a starting from 9a via the formation of
styrene derivative 12a that undergoes subsequent intramolecular carbocyclization (Scheme 7).
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Me
Me
COOEt
Me
1
2
3
4
5
TFA
CF3CO2H
CF3CO2Et
Me
80 °C, 24 h
H
2a
1a
Me Me
Me
H
O
6
7
OH
Me
8
9
intramolecular decarboxylation
and cyclodimerization
3a
H
O
11a
Me
Me
Me
H
10
11
12
13
14
15
16
17
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OH
Me
H
O
O
H
H
H
H
O
Me
H
O
Me
11a
Me
H
H
CO2
COOEt
Me
TFA
80 °C, 24 h
9a
10a
CF3CO2H
CF3CO2Et
intramolecular decarboxylation
and intramolecular cyclization
H
COOH
Me
H
H
12a
and CO2
H
Scheme 7: Possible mechanism for the formation of indanes 2 and 10.
In summary, we have developed a domino inter and intra-molecular carbocyclizations, for the synthesis of
functionalized indanes. Notably, this decarboxylation was promoted by acid without the aid of metal-
catalysts. Significantly, the overall domino protocol involves the cleavage of two σ-bonds (C-O and C-C)
and construction of one or two new C-C σ-bond(s) via carbocylization or cyclodimerization, respectively.
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1
2
3
4
Experimental:
5
6
7
8
9
1
General considerations: IR spectra were recorded on FTIR spectrophotometer. H NMR spectra were recorded
on 400 MHz spectrometer at 295 K in CDCl3; chemical shifts (δ ppm) and coupling constants (Hz) are reported in
standard fashion with reference to either internal standard tetramethylsilane (TMS) (δH =0.00 ppm) or CHCl3 (δH
= 7.25 ppm). 13C NMR spectra were recorded at RT in CDCl3; chemical shifts (δ ppm) are reported relative to
CHCl3 [δC = 77.00 ppm (central line of triplet)]. In the 13C NMR, the nature of carbons (C, CH, CH2 and CH3)
was determined by recording the DEPTꢀ135 spectra, and is given in parentheses and noted as s = singlet (for C), d
10
11
12
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1
= doublet (for CH), t = triplet (for CH2) and q = quartet (for CH3). In the HꢀNMR, the following abbreviations
were used throughout: s = singlet, d = doublet, t = triplet, q = quartet, qui =quintet, sept = septet, dd = doublet of
1
13
doublet, m = multiplet and br. s = broad singlet. The assignment of signals was confirmed by H, C CPD and
DEPT spectra. Highꢀresolution mass spectra (HRꢀMS) were recorded on a QꢀTOF electron spray ionization (ESI)
mode and atmospheric pressure chemical ionization (APCI) modes. All small scale dry reactions were carried out
using Schlenk tubes under inert atmosphere. Reactions were monitored by TLC on silica gel using a combination
of hexane and ethyl acetate as eluents. Reactions were generally run under argon or a nitrogen atmosphere.
Solvents were distilled prior to use; petroleum ether with a boiling range of 60 to 80 °C was used. Trifluoroacetic
acid with the purity of 98% was purchased from local sources and used as received. Acme’s silica gel (60–120
mesh) was used for column chromatography (approximately 20 g per one gram of crude material).
GPꢀ1 (General procedure for the synthesis of esters 9): To the oil suspension of 60% NaH (192.4 mg, 4.8
mmol) in THF (8 mL) at 0 οC under nitrogen atmosphere, was added triethylphosphanoaetate (1.3 g, 5.8 mmol) in
drop wise and allowed the reaction mixture to stir at the same temperature for 0.25 h for the generation of ylide.
To this resultant reaction mixture was added ketone 13 (500‒728 mg, 2.40 mmol) in dry THF (1.5 mL) and
allowed the reaction mixture to stir at 65 οC for 12 h. Progress of the ester 9 formation was monitored by TLC till
the reaction is completed. Then, the mixture was quenched by the addition of aqueous NH4Cl solution and then
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extracted with ethyl acetate (3 × 20 mL). The organic layer was washed with saturated NaCl solution, dried
(Na2SO4), and filtered. Evaporation of the solvent under reduced pressure and purification of the crude material
by silica gel column chromatography (petroleum ether/ethyl acetate) furnished the esters 9 (36‒44%) and 9’ (46‒
58%) as viscous liquid.
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GPꢀ2 (General procedure for the synthesis of indanes 2 and 10): In an oven dried Schlenk tube, were added
ester 1/9 (87.7‒113.5 mg, 0.43 mmol) and trifluoroacetic acid (3.0 mL) at room temperature under nitrogen
atmosphere and allowed the reaction mixture to stir at 80 °C for 12 to 48 h. Progress of the indane 2/10 formation
was monitored by TLC till the reaction is completed. Then, the mixture was quenched by the addition of aqueous
NaHCO3 solution and then extracted with ethyl acetate (3 × 20 mL). The organic layer was washed with saturated
NaCl solution, dried (Na2SO4), and filtered. Evaporation of the solvent under reduced pressure and purification of
the crude material by silica gel column chromatography (petroleum ether/ethyl acetate) furnished the indane 2/10
(65‒94%) as viscous oil/solid and 1ꢀmethylꢀ1ꢀphenylꢀtetralin 10i as viscous oil (52%).
1,1,3ꢀTrimethylꢀ3ꢀphenylindane (2a): GPꢀ2 was carried out with ester 1a (95 mg, 0.50 mmol) and trifluroacetic
acid (3 mL) for indane formation at 80 °C for 24 h. Purification of the crude material by silica gel column
chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 2a (50.7 mg, 86%) as colour
less viscous oil. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(1a) = 0.30, Rf(2a) = 0.90, UV detection]. 1H
NMR (CDCl3 400 MHz): δ=7.30‒7.08 (m, 9H), 2.39 (d, 1H, J = 13.2 Hz), 2.20 (d, 1H, J = 13.2 Hz), 1.67 (s, 3H),
1.33 (s, 3H), 1.02 (s, 3H) ppm. 13C NMR (CDCl3, 100 MHz): δ=152.2 (Cq), 151.0 (Cq), 148.7 (Cq), 128.0 (2 ×
CH), 127.2 (CH), 126.7 (2 × CH), 126.6 (CH), 125.4 (CH), 125.0 (CH), 122.5 (CH), 59.2 (CH2), 50.8 (Cq), 42.8
(Cq), 30.9 (CH3), 30.6 (CH3), 30.4 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1): νmax=2959, 1486, 1401, 1094,
1012, 820 cmꢀ1.
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5ꢀFluoroꢀ3ꢀ(4ꢀfluorophenyl)ꢀ1,1,3ꢀtrimethylindane (2b): GPꢀ2 was carried out with ester 1b (104 mg, 0.50
mmol) and trifluroacetic acid (3 mL) for indane formation at 80 °C for 24 h. Purification of the crude material by
silica gel column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 2b (61.9 mg,
91%) as colour less viscous oil. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(1b) = 0.30, Rf(2b) = 0.90,
UV detection]. 1H NMR (CDCl3 400 MHz): δ = 7.16‒7.08 (m, 3H), 7.01‒6.89 (m, 3H), 6.77 (dd, 1H, J = 9.3 and
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13
2.5 Hz), 2.37 (d, 1H, J = 12.7 Hz), 2.23 (s, 1H, J = 12.7 Hz), 1.66 (s, 3H), 1.33 (s, 3H), 1.03 (s, 3H) ppm. C
NMR (CDCl3, 100 MHz): δ = 163.5 (d, J = 243.6 Hz, Cq), 162.2 (d, J = 244.3 Hz, Cq), 150.8 (d, J = 7.3 Hz, Cq),
147.5 (Cq), 146.0 (d, J = 2.9 Hz, Cq), 128.1 (d, 2C, J = 7.3 Hz, 2 × CH), 123.8 (d, J = 8.8 Hz, CH), 114.8 (d, 2C, J
= 21.3 Hz, 2 × CH), 114.4 (d, J = 22.0 Hz, CH), 111.4 (d, J = 22.0 Hz, CH), 59.5 (t, CH2), 50.2 (d, J = 1.5 Hz,
Cq), 42.4 (Cq), 30.8 (CH3), 30.7 (CH3), 30.4 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1): νmax=2959, 1605, 1507,
1422, 1227, 1163, 1015, 821 cmꢀ1.
5ꢀChloroꢀ3ꢀ(4ꢀchlorophenyl)ꢀ1,1,3ꢀtrimethylindane (2c): GPꢀ2 was carried out with ester 1c (112.4 mg, 0.50
mmol) and trifluroacetic acid (3 mL) for indane formation at 80 °C for 12 h. Purification of the crude material by
silica gel column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 2c (68.1 mg,
89%) as colour less viscous oil. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(1c) = 0.30, Rf(2c) = 0.90,
UV detection]. 1H NMR (CDCl3 400 MHz): δ = 7.28‒7.16 (m, 3H), 7.15‒7.06 (m, 3H), 7.03 (d, 1H, J = 1.9 Hz),
2.34 (d, 1H, J = 12.7 Hz), 2.20 (d, 1H, J = 13.2 Hz), 1.64 (s, 3H), 1.31 (s, 3H), 1.02 (s, 3H) ppm. 13C NMR
(CDCl3, 100 MHz): δ = 150.6 (Cq), 150.3 (Cq), 148.7 (Cq), 132.4 (Cq), 131.5 (Cq), 128.2 (2 × CH), 128.0 (2 ×
CH), 127.7 (CH), 124.9 (CH), 123.9 (CH), 59.1 (CH2), 50.4 (Cq), 42.6 (Cq), 30.6 (2 × CH3), 30.3 (CH3) ppm. IR
(MIRꢀATR, 4000–600 cmꢀ1): νmax = 2958, 1486, 1401, 1095, 1013, 820, 723 cmꢀ1.
5ꢀBromoꢀ3ꢀ(4ꢀbromophenyl)ꢀ1,1,3ꢀtrimethylindane (2d): GPꢀ2 was carried out with ester 1d (134.5 mg, 0.50
mmol) and trifluroacetic acid (3 mL) for indane formation at 80 °C for 12 h. Purification of the crude material by
silica gel column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 2d (94.6 mg,
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96%) as colour semiꢀsolid. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(1d) = 0.30, Rf(2d) = 0.90, UV
detection]. 1H NMR (CDCl3, 400 MHz): δ = 7.41 (dd, 1H, J = 7.8 and 2.0 Hz), 7.37 (dd, 2H, J = 8.3 and 2.0 Hz),
7.19 (d, 1H, J = 2.0 Hz), 7.08 (d, 1H, J = 7.8 Hz), 7.04 (dd, 2H, J = 8.3 and 2.0 Hz), 2.36 (d, 1H, J = 13.2 Hz),
2.36 (d, 1H, J = 13.2 Hz), 1.64 (s, 3H), 1.32 (s, 3H), 1.03 (s, 3H) ppm. 13C NMR (CDCl3, 100 MHz): δ = 151.2
(Cq), 150.7 (Cq), 149.3 (Cq), 131.2 (2 × CH), 130.6 (CH), 128.5 (2 × CH), 127.9 (CH), 124.5 (CH), 120.5 (Cq),
119.7 (Cq), 59.1 (CH2), 50.6 (Cq), 42.7 (Cq), 30.6 (2 × CH3), 30.3 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
1
2
3
4
5
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7
8
9
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ν
max = 2961, 2927, 1485, 1464, 1397, 1368, 1073, 1008, 826 cmꢀ1.
1,3,3,4ꢀTetramethylꢀ1ꢀ(2ꢀmethylphenyl)indane (2e): GPꢀ2 was carried out with ester 1e (102 mg, 0.50 mmol)
and trifluroacetic acid (3 mL) for indane formation at 80 °C for 24 h. Purification of the crude material by silica
gel column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 2e (50.2 mg, 76%)
as colour less viscous oil. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(1e) = 0.30, Rf(2e) = 0.90, UV
detection]. 1H NMR (CDCl3 400 MHz): δ = 7.20‒7.00 (m, 6H, ArH), 6.88 (d, 1H, J=7.5 Hz), 2.58 (d, 1H, J=13.2
13
Hz), 2.48 (s, 3H), 2.22 (s, 3H, CH3), 2.15 (d, 1H, J=13.2 Hz), 1.79 (s, 3H), 1.53 (s, 3H), 1.27 (s, 3H) ppm. C
NMR (CDCl3, 100 MHz): δ = 151.4 (Cq), 147.6 (Cq), 147.4 (Cq), 136.1 (Cq), 133.9 (Cq), 132.5 (CH), 129.6 (CH),
127.5 (CH), 126.9 (CH), 126.0 (CH), 125.2 (CH), 122.6 (CH), 57.9 (CH2), 50.2 (Cq), 44.2 (s, Cq), 30.9 (CH3),
29.5 (CH3), 28.1 (CH3), 22.4 (CH3), 19.3 (CH3) ppm. IR (neat; MIRꢀATR, 4000–600 cmꢀ1): νmax=2958, 1568,
1524, 1455, 1361, 1313, 1192, 1018, 810, 724 cmꢀ1.
1,1,3,5ꢀTetramethylꢀ3ꢀ(4ꢀmethylphenyl)indane (2f): GPꢀ2 was carried out with ester 1f (102 mg, 0.50 mmol)
and trifluroacetic acid (3 mL) for indane formation at 80 °C for 24 h. Purification of the crude material by silica
gel column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 2f (48.8 mg, 74%)
as colour less viscous oil. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(1f) = 0.30, Rf(2f) = 0.90, UV
1
detection]. H NMR (CDCl3 400 MHz): δ = 7.20‒7.05 (m, 6H), 6.95 (s, 1H), 2.41 (d, 1H, J = 13.2 Hz), 2.40 (s,
3H), 2.34 (s, 3H), 2.23 (d, 1H, J = 13.2 Hz), 1.71 (s, 3H), 1.37 (s, 3H), 1.09 (s, 3H) ppm. 13C NMR (CDCl3, 100
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MHz): δ = 149.3 (Cq), 149.1 (Cq), 148.1 (Cq), 136.1 (Cq), 134.8 (Cq), 128.6 (2 × CH), 128.0 (CH), 126.6 (2 ×
CH), 125.4 (CH), 122.2 (CH), 59.5 (CH2), 50.3 (Cq), 42.5 (Cq), 30.8 (2 × CH3), 30.5 (CH3), 21.4 (CH3), 20.9
(CH3) ppm. IR (neat; MIRꢀATR, 4000–600 cmꢀ1): νmax=2956, 1510, 1454, 1360, 1312, 1188, 1018, 816, 725 cmꢀ1.
1
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7
8
9
5ꢀMethoxyꢀ1ꢀ(3ꢀmethoxyphenyl)ꢀ1,3,3ꢀtrimethylindane (2g) and 4ꢀmethoxyꢀ3ꢀ(3ꢀmethoxyphenyl)ꢀ1,1,3ꢀ
trimethylindane (2g'): GPꢀ2 was carried out with ester 1g (110.1 mg, 0.50 mmol) and trifluroacetic acid (3 mL)
for indane formation at 80 °C for 24 h. Purification of the crude material by silica gel column chromatography
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(petroleum ether/ethyl acetate 100:0 to 97:3) furnished 3:1 regioisomeric mixture indanes 2g and 2g′ (63.7 mg,
86%) as colour less viscous liquid. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(1g) = 0.30, Rf(2g and
2g′) = 0.80, UV detection]. 1H NMR (CDCl3 400 MHz; peaks due to the major isomer 2g): δ = 7.19 (dd, 1H, J =
7.8 and 7.8 Hz), 7.07 (d, 1H, J = 8.3 Hz), 6.90‒6.65 (m, 5H), 3.86 (s, 3H), 3.77 (s, 3H), 2.46 (d, 1H, J = 12.7 Hz),
2.21 (d, 1H, J = 12.7 Hz), 1.68 (s, 3H), 1.35 (s, 3H), 1.05 (s, 3H) ppm. 13C NMR (CDCl3, 100 MHz; peaks due to
the major isomer 2g): δ = 159.3 (Cq), 159.2 (Cq), 153.7 (Cq), 153.1 (Cq), 140.6 (Cq), 128.8 (CH), 125.5 (CH),
119.3 (CH), 113.3 (CH), 112.5 (CH), 109.8 (CH), 107.7 (CH), 59.4 (CH2), 55.3 (CH3), 55.0 (CH3), 50.1 (Cq),
42.8 (Cq), 31.1 (CH3), 30.4 (CH3), 30.2 (CH3), 20.9 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1): νmax=2958, 1591,
1507, 1313, 1251, 1183, 1060, 1036, 826 cmꢀ1.
5ꢀMethoxyꢀ3ꢀ(4ꢀmethoxyphenyl)ꢀ1,1,3ꢀtrimethylindane (2h): GPꢀ2 was carried out with ester 1h (110.1 mg,
0.50 mmol) and trifluroacetic acid (3 mL) for indane formation at 80 °C for 24 h. Purification of the crude
material by silica gel column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane
2h (38.5 mg, 52%) as pale yellow viscous liquid. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(1h) =
0.30, Rf(2h) = 0.80, UV detection]. 1H NMR (CDCl3 400 MHz): δ = 7.15‒7.05 (m, 3H), 6.90‒6.75 (m, 3H), 6.63
(s, 1H), 3.78 (s, 3H), 3.77 (s, 3H), 2.34 (d, 1H, J = 13.2 Hz), 2.19 (d, 1H, J = 13.2 Hz), 1.66 (s, 3H), 1.31 (s, 3H),
1.03 (s, 3H) ppm. 13C NMR (CDCl3, 100 MHz): δ = 158.9 (Cq), 157.3 (Cq), 150.5 (Cq), 144.5 (Cq), 143.0 (Cq),
127.6 (2 × CH), 123.1 (CH), 113.2 (2 × CH), 113.1 (CH), 109.9 (CH), 59.7 (CH2), 55.4 (CH3), 55.2 (CH3), 50.1
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(Cq), 42.1 (Cq), 30.9 (2 × CH3), 30.8 (CH3), 30.5 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1): νmax=2954, 1597,
1511, 1311, 1249, 1180, 1035, 825 cmꢀ1.
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5ꢀEthylꢀ3ꢀ(4ꢀethylphenyl)ꢀ1,1,3ꢀtrimethylindane (2j): GPꢀ2 was carried out with ester 1j (109 mg, 0.50 mmol)
and trifluroacetic acid (3 mL) for indane formation at 80 °C for 48 h. Purification of the crude material by silica
gel column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 2j (47.4 mg, 65%)
as colour less viscous oil. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(1j) = 0.30, Rf(2j) = 0.90, UV
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detection]. IR (MIRꢀATR, 4000–600 cmꢀ1): νmax = 2961, 1510, 1455, 1369, 1311, 1017, 828 cmꢀ1. H NMR
(CDCl3 400 MHz): δ = 7.20‒7.05 (m, 6H), 6.94 (s, 1H), 2.75‒2.55 (m, 4H), 2.36 (d, 1H, J = 12.7 Hz), 2.18 (d,
1H, J = 12.7 Hz), 1.67 (s, 3H), 1.33 (s, 3H), 1.30‒1.15 (m, 6H), 1.03 (s, 3H) ppm. 13C NMR (CDCl3, 100 MHz):
δ = 149.5 (Cq), 149.0 (Cq), 148.3 (Cq), 142.6 (Cq), 141.1 (Cq), 127.3 (2 × CH), 126.8 (CH), 126.6 (2 × CH), 124.3
(CH), 122.2 (CH), 59.5 (CH2), 50.4 (Cq), 42.5 (Cq), 30.9 (CH3), 30.7 (CH3), 30.5 (CH3), 28.8 (CH2), 28.2 (CH2),
15.8 (CH3), 15.4 (CH3) ppm.
1,1,3ꢀTrimethylꢀ3ꢀ(2ꢀnaphthyl)ꢀ2,3ꢀdihydroꢀ1Hꢀcyclopenta[b]naphthalene (2k): GPꢀ2 was carried out with
ester 1k (120.2 mg, 0.50 mmol) and trifluroacetic acid (3 mL) for indane formation at 80 °C for 24 h. Purification
of the crude material by silica gel column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished
the indane 2k (57.2 mg, 68%) as colour less viscous liquid. [TLC control (petroleum ether/ethyl acetate 99:1),
Rf(1k) = 0.30, Rf(2k) = 0.90, UV detection]. 1H NMR (CDCl3 400 MHz): δ = 7.90‒7.70 (m, 5H), 7.63 (d, 1H, J =
8.3 Hz), 7.50‒7.20 (m, 4H), 7.27 (dd, 1H, J = 8.3 and 6.8 Hz), 7.20 (d, 1H, J = 6.8 Hz), 7.08 (dd, 1H, J = 8.3 and
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6.8 Hz), 2.44 (d, 1H, J = 13.7 Hz), 2.36 (d, 1H, J = 13.7 Hz), 2.06 (s, 3H), 1.43 (s, 3H), 1.39 (s, 3H) ppm. C
NMR (CDCl3, 100 MHz): δ = 149.4 (Cq), 148.6 (Cq), 142.7 (Cq), 133.9 (Cq), 133.3 (Cq), 131.7 (Cq), 129.7 (Cq),
128.8 (CH), 128.7 (CH), 128.1 (CH), 128.0 (CH), 127.4 (CH), 126.3 (CH), 125.8 (CH), 125.6 (CH), 125.3 (CH),
125.0 (CH), 124.5 (CH), 123.5 (CH), 121.3 (CH), 61.3 (CH2), 52.1 (Cq), 43.3 (Cq), 31.4 (CH3), 31.3 (CH3), 28.1
(CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1): νmax=2960, 1560, 1456, 1377, 1277, 1138, 820, 746 cmꢀ1.
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1ꢀMethylꢀ1,3,3ꢀtriphenylindane (2l): GPꢀ2 was carried out with ester 1l (126 mg, 0.50 mmol) and trifluroacetic
acid (3 mL) for indane formation at 80 °C for 24 h. Purification of the crude material by silica gel column
chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 2l (83 mg, 92%) as colour less
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viscous liquid. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(1l) = 0.30, Rf(2l) = 0.90, UV detection]. H
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NMR (CDCl3 400 MHz): δ = 7.35‒6.95 (m, 19H), 3.39 (d, 1H, J=13.2 Hz), 3.09 (d, 1H, J=13.2 Hz), 1.54 (s, 3H)
ppm. 13C NMR (CDCl3, 100 MHz): δ = 150.5 (Cq), 149.3 (Cq), 148.8 (Cq), 148.5 (Cq), 147.4 (Cq), 128.7 (2 ×
CH), 128.6 (2 × CH), 127.9 (2 × CH), 127.8 (2 × CH), 127.6 (2 × CH), 127.4 (CH), 127.3 (CH), 126.9 (2 × CH),
126.8 (CH), 126.0 (CH), 125.6 (CH), 125.5 (CH), 125.0 (CH), 61.3 (CH2), 60.9 (Cq), 51.1 (Cq), 28.8 (CH3) ppm.
IR (MIRꢀATR, 4000–600 cmꢀ1): νmax=2959, 1594, 1453, 1374, 1277, 1132, 818, 748 cmꢀ1.
Ethylꢀtrimethylꢀphenylindanes (6 and 6'): GPꢀ2 was carried out with ester 5 (102 mg, 0.50 mmol) and
trifluroacetic acid (3 mL) for indane formation at 80 °C for 24 h. Purification of the crude material by silica gel
column chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the mixture of indanes 6 and 6'
(60.1 mg, 91%) as colour less viscous liquid. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(5) = 0.30, Rf(6
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and 6') = 0.90, UV detection]. H NMR (CDCl3 400 MHz): δ = 7.35‒7.00 (m, 8H), 6.84 (d, 1H, J = 7.3 Hz),
2.20‒1.95 (m, 1H), 1.49 (s, 3H, CH3), 1.17 (s, 3H, CH3) 0.91 (d, 3H, J = 7.3 Hz), 0.79 (q, 2H, J = 7.3 Hz), 0.65 (t,
3H, J = 7.3 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ = 151.8 (Cq), 150.8 (Cq), 150.2 (Cq), 127.8 (2 × CH), 127.2
(2 × CH), 127.0 (ArCH), 126.9 (ArCH), 126.7 (ArCH), 125.6 (ArCH), 124.8 (ArCH), 123.2 (ArCH), 55.1 (CH),
52.0 (Cq), 46.2 (Cq), 35.5 (CH3), 33.4 (CH3), 23.1 (CH2), 9.1 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
νmax=2960, 1594, 1457, 1378, 1266, 1136, 820, 724 cmꢀ1. HRꢀMS (APCI+) m/z calculated for [C20H25]+ =
[M+H]+: 265.1951; found: 265.1959.
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1ꢀMethylnaphthalene (8): GPꢀ2 was carried out with ester 7 (108 mg, 0.50 mmol) and trifluroacetic acid (3 mL)
for indane formation at 80 °C for 24 h. Purification of the crude material by silica gel column chromatography
(petroleum ether/ethyl acetate 100:0 to 99:1) furnished the 1ꢀmethylnaphthalene 8 (38 mg, 53%) as colour less
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viscous liquid. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(7) = 0.28, Rf(8) = 0.90, UV detection]. H
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NMR (CDCl3 400 MHz): δ = 8.14 (d, 1H, J = 7.9 Hz), 8.00 (d, 1H, J = 7.4 Hz), 7.86 (d, 1H, J = 7.9 Hz), 7.75‒
7.40 (m, 4H, ArH), 2.84 (s, 3H, CH3) ppm. 13C NMR (CDCl3, 100 MHz): δ = 134.2 (Cq), 133.5 (Cq), 132.6 (Cq),
128.5 (CH), 126.5 (CH), 126.3 (CH), 125.6 (CH), 125.5 (CH), 125.4 (CH), 124.1 (CH), 19.3 (CH3) ppm. IR
(MIRꢀATR, 4000–600 cmꢀ1): νmax=2959, 1590, 1462, 1378, 1276, 1134, 820, 738 cmꢀ1.
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Ethylꢀ3ꢀphenylꢀ5ꢀphenylpentꢀ2ꢀenoate (9a & 9a’): GPꢀ1 was carried out with NaH (192.4 mg, 4.8 mmol),
triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13a (500.0 mg, 2.40 mmol) and dry THF (9 mL) for esters
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formation 9a and 9a’ at 65 C for 12 h. Purification of the crude material by silica gel column chromatography
(petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9a (291.2 mg, 44%) and 9a’ (295.9 mg, 44%) as
colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13a) = 0.35, Rf(9a) = 0.65,
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Rf(9a’)=0.60, UV detection]. H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9a): δ = 7.52‒7.32 (m, 5H),
7.32‒7.19 (m, 4H), 7.17 (t, 1H, J = 7.3 Hz), 6.07 (s, 1H), 4.20 (q, 2H, J = 7.3 Hz), 3.50–3.30 (m, 2H), 2.80–2.65
(m, 2H), 1.30 (t, 3H, J = 7.3 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ = 166.3 (Cq), 159.3 (Cq), 141.5 (Cq), 141.0
(Cq), 129.0 (CH), 128.6 (2 × CH), 128.4 (2 × CH), 128.2 (2 × CH), 126.7 (2 × CH), 125.9 (CH), 117.8 (CH), 59.9
(CH2), 35.1 (CH2), 33.1 (CH2), 14.3 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
νmax = 2980, 2929, 1709, 1623,
1494, 1453, 1349, 1161, 1036, 745, 697 cmꢀ1. HRꢀMS (ESI+) m/z calculated for [C19H21O2]+ = [M+H]+: 281.1536;
found: 281.1546.
Ethylꢀ3ꢀ(4ꢀchlorophenyl)ꢀ5ꢀphenylpentꢀ2ꢀenoate (9b & 9b’): GPꢀ1 was carried out with NaH (192.4 mg, 4.8
mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13b (587.3 mg, 2.40 mmol) and dry THF (9 mL) for
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esters formation 9b and 9b’ at 65 C for 12 h. Purification of the crude material by silica gel column
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chromatography (petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9b (317.5 mg, 42%) and 9b’
(340.3 mg, 45%) as colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13b) = 0.35,
Rf(9b) = 0.65, Rf(9b’) = 0.60, UV detection]. 1H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9b): δ = 7.29 (d,
2H, J = 8.8 Hz), 7.26 (d, 2H, J = 8.8 Hz), 7.22‒7.05 (m, 5H), 5.95 (s, 1H), 4.11 (q, 2H, J = 7.3 Hz), 3.35–3.25 (m,
2H), 2.70–2.55 (m, 2H), 1.22 (t, 3H, J = 7.3 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ = 166.1 (Cq), 157.9 (Cq),
141.2 (Cq), 139.4 (Cq), 134.9 (Cq), 128.8 (2 × CH), 128.4 (2 × CH), 128.3 (2 × CH), 128.0 (2 × CH), 126.0 (CH),
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118.2 (CH), 60.0 (CH2), 35.0 (CH2), 32.9 (CH2), 14.3 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
νmax = 2979,
2928, 1708, 1622, 1492, 1454, 1368, 1261, 1159, 1093, 1011, 824, 746, 697 cmꢀ1. HRꢀMS (ESI+) m/z calculated
for [C19H20ClO2]+ = [M+H]+: 315.1146; found: 315.1143.
Ethylꢀ3ꢀ(4ꢀbromophenyl)ꢀ5ꢀphenylpentꢀ2ꢀenoate (9c & 9c’): GPꢀ1 was carried out with NaH (192.4 mg, 4.8
mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13c (694.1 mg, 2.40 mmol) and dry THF (9 mL) for
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esters formation 9c and 9c’ at 65 C for 12 h. Purification of the crude material by silica gel column
chromatography (petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9c (319.1 mg, 37%) and 9c’
(457.2 mg, 53%) as colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13c) = 0.37,
Rf(9c) = 0.66, Rf(9c’) = 0.62, UV detection]. 1H NMR (CDCl3, 400 MHz, peaks due to Zꢀisomer 9c’): δ = 7.49 (d,
2H, J=8.3 Hz), 7.27 (dd, 2H, J = 7.8 and 7.3 Hz), 7.19 (t, 1H, J = 7.3 Hz), 7.11 (d, 2H, J = 7.8 Hz), 7.06 (d, 2H, J
= 8.3 Hz), 5.90 (s, 1H), 4.00 (q, 2H, J = 7.3 Hz), 2.82–2.60 (m, 4H), 1.10 (t, 3H, J = 7.3 Hz) ppm. 13C NMR
(CDCl3, 100 MHz): δ = 165.6 (Cq), 157.3 (Cq), 140.5 (Cq), 138.6 (Cq), 131.1 (2 × CH), 129.0 (2 × CH), 128.5 (2 ×
CH), 128.2 (2 × CH), 126.2 (CH), 121.8 (Cq), 118.2 (CH), 60.0 (CH2), 41.8 (CH2), 33.7 (CH2), 14.0 (CH3) ppm.
IR (MIRꢀATR, 4000–600 cmꢀ1):
νmax = 2979, 2924, 1722, 1641, 1487, 1454, 1278, 1225, 1160, 1038, 1010, 824,
699 cmꢀ1. HRꢀMS (ESI+) m/z calculated for [C19H20BrO2]+ = [M+H]+: 359.0641; found: 359.0647.
Ethylꢀ3ꢀ(4ꢀethylphenyl)ꢀ5ꢀphenylpentꢀ2ꢀenoate (9d & 9d’): GPꢀ1 was carried out with NaH (192.4 mg, 4.8
mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13d (587.3 mg, 2.40 mmol) and dry THF (9 mL) for
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esters formation 9d and 9d’ at 65 C for 12 h. Purification of the crude material by silica gel column
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chromatography (petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9d (296.2 mg, 40%) and 9d’
(348.1 mg, 47%) as colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13d) = 0.35,
Rf(9d) = 0.65, Rf(9d’) = 0.60, UV detection]. 1H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9d): δ = 7.41 (d,
2H, J = 7.8 Hz), 7.32‒7.10 (m, 7H), 6.08 (s, 1H), 4.20 (q, 2H, J = 7.3 Hz), 3.50–3.30 (m, 2H), 2.80–2.66 (m, 2H),
2.68 (q, 2H, J = 7.8 Hz), 1.30 (t, 3H, J = 7.3 Hz), 1.26 (t, 3H, J = 7.8 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ =
166.5 (Cq), 159.3 (Cq), 145.4 (Cq), 141.7 (Cq), 138.2 (Cq), 128.5 (2 × CH), 128.3 (2 × CH), 128.1 (2 × CH), 126.7
(2 × CH), 125.9 (CH), 116.9 (CH), 59.8 (CH2), 35.3 (CH2), 33.0 (CH2), 28.5 (CH2), 15.4 (CH3), 14.3 (q, CH3)
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ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
νmax = 2980, 2927, 1709, 1621, 1455, 1366, 1263, 1155, 1091, 1013, 825,
750, 699 cmꢀ1. HRꢀMS (ESI+) m/z calculated for [C21H25O2]+ = [M+H]+: 309.1849; found: 309.1846.
Ethyl (2E)ꢀ5ꢀ(4ꢀmethylphenyl)ꢀ3ꢀphenylpentꢀ2ꢀenoate (9e & 9e’): GPꢀ1 was carried out with NaH (192.4 mg,
4.8 mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13e (538.3 mg, 2.40 mmol) and dry THF (9 mL)
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for esters formation 9e and 9e’ at 65 C for 12 h. Purification of the crude material by silica gel column
chromatography (petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9e (303.8 mg, 43%) and 9e’
(332.1 mg, 47%) as colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13e) = 0.35,
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Rf(9e) = 0.65, Rf(9e’) = 0.60, UV detection]. H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9e): δ = 7.52‒
7.31 (m, 5H), 7.12 (d, 2H, J = 7.3 Hz), 7.08 (d, 2H, J = 7.3 Hz), 6.06 (s, 1H), 4.20 (q, 2H, J = 7.3 Hz), 3.45–3.25
(m, 2H), 2.75–2.62 (m, 2H), 2.31 (s, 3H), 1.31 (t, 3H, J = 7.3 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ = 166.3
(Cq), 159.4 (Cq), 141.1 (Cq), 138.5 (Cq), 135.3 (Cq), 128.9 (3 × CH), 128.6 (2 × CH), 128.3 (2 × CH), 126.7 (2 ×
CH), 117.7 (CH), 59.9 (CH2), 34.7 (CH2), 33.3 (CH2), 21.0 (CH3), 14.3 (q, CH3) ppm. IR (MIRꢀATR, 4000–600
cmꢀ1): max = 2979, 2925, 1708, 1621, 1514, 1446, 1368, 1263, 1153, 1038, 1026, 874, 808, 770, 695 cmꢀ1. HRꢀ
ν
MS (ESI+) m/z calculated for [C20H23O2]+ = [M+H]+: 295.1693; found: 295.1691.
Ethylꢀ3ꢀ(4ꢀchlorophenyl)ꢀ5ꢀ(4ꢀmethylphenyl)pentꢀ2ꢀenoate (9f & 9f’): GPꢀ1 was carried out with NaH (192.4
mg, 4.8 mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13f (620.9 mg, 2.40 mmol) and dry THF (9
ο
mL) for esters formation 9f and 9f’ at 65 C for 12 h. Purification of the crude material by silica gel column
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chromatography (petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9f (315.6 mg, 40%) and 9f’
(363.1 mg, 46%) as colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13f) = 0.35,
Rf(9f) = 0.65, Rf(9f’) = 0.60, UV detection]. 1H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9f): δ = 7.38 (d,
2H, J = 8.8 Hz), 7.35 (d, 2H, J = 8.8 Hz), 7.10 (d, 2H, J = 8.3 Hz), 7.07 (d, 2H, J = 8.3 Hz), 6.03 (s, 1H), 4.21 (q,
2H, J = 7.3 Hz), 3.40–3.25 (m, 2H), 2.75–2.60 (m, 2H), 2.31 (s, 3H), 1.31 (t, 3H, J = 7.3 Hz) ppm. 13C NMR
(CDCl3, 100 MHz): δ = 166.1 (Cq), 158.0 (Cq), 139.5 (Cq), 138.2 (Cq), 135.4 (Cq), 134.9 (Cq), 129.0 (2 × CH),
128.8 (2 × CH), 128.3 (2 × CH), 128.0 (2 × CH), 118.1 (CH), 60.0 (CH2), 34.6 (CH2), 33.1 (CH2), 21.0 (CH3),
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14.3 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
νmax = 2980, 2926, 1713, 1624, 1491, 1368, 1172, 1094, 1012,
829 cmꢀ1. HRꢀMS (ESI+) m/z calculated for [C20H22ClO2]+ = [M+H]+: 329.1303; found: 329.1302.
Ethylꢀ3ꢀ(4ꢀbromophenyl)ꢀ5ꢀ(4ꢀmethylphenyl)pentꢀ2ꢀenoate (9g & 9g’): GPꢀ1 was carried out with NaH
(192.4 mg, 4.8 mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13g (727.7 mg, 2.40 mmol) and dry
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THF (9 mL) for esters formation 9g and 9g’ at 65 C for 12 h. Purification of the crude material by silica gel
column chromatography (petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9g (322.7 mg, 36%)
and 9g’ (492.4 mg, 55%) as pale yellow viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5),
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Rf(13g) = 0.37, Rf(9g) = 0.66, Rf(9g’) = 0.62, UV detection]. H NMR (CDCl3, 400 MHz, peaks due to Zꢀisomer
9g’): δ = 7.48 (d, 2H, J = 8.3 Hz), 7.15‒7.02 (m, 4H), 7.00 (d, 2H, J = 8.3 Hz), 5.89 (s, 1H), 3.99 (q, 2H, J = 7.3
Hz), 2.75–2.58 (m, 4H), 2.31 (s, 3H), 1.10 (t, 3H, J = 7.3 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ = 165.7 (Cq),
157.4 (Cq), 138.7 (Cq), 137.4 (Cq), 135.7 (Cq), 131.1 (2 × CH), 129.1 (2 × CH), 129.0 (2 × CH), 128.1 (2 × CH),
121.8 (Cq), 118.1 (CH), 59.9 (CH2), 42.0 (CH2), 33.3 (CH2), 21.0 (CH3), 14.0 (CH3) ppm. IR (MIRꢀATR, 4000–
600 cmꢀ1): max = 2980, 2924, 1721, 1640, 1514, 1490, 1377, 1223, 1158, 1091, 1039, 1014, 830, 809 cmꢀ1. HRꢀ
ν
MS (ESI+) m/z calculated for [C20H22BrO2]+ = [M+H]+: 373.0798; found: 373.0795.
Ethylꢀ3ꢀ(4ꢀethylphenyl)ꢀ5ꢀ(4ꢀmethylphenyl)pentꢀ2ꢀenoate (9h & 9h’): GPꢀ1 was carried out with NaH (192.4
mg, 4.8 mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13h (605.5 mg, 2.40 mmol) and dry THF (9
ο
mL) for esters formation 9h and 9h’ at 65 C for 12 h. Purification of the crude material by silica gel column
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chromatography (petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9h (309.6 mg, 40%) and 9h’
(371.5 mg, 48%) as colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13h) = 0.35,
Rf(9h) = 0.65, Rf(9h’) = 0.60, UV detection]. 1H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9h): δ = 7.42 (d,
2H, J = 8.3 Hz), 7.23 (d, 2H, J = 8.3 Hz), 7.15 (d, 2H, J = 7.8 Hz), 7.09 (d, 2H, J = 7.8 Hz), 6.08 (s, 1H), 4.21 (q,
2H, J = 7.3 Hz), 3.45–3.30 (m, 2H), 2.75–2.62 (m, 2H), 2.68 (q, 2H, J = 7.8 Hz), 2.32 (s, 3H), 1.31 (t, 3H, J = 7.3
Hz), 1.27 (t, 3H, J = 7.8 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ=166.5 (Cq), 159.3 (Cq), 145.4 (Cq), 138.6 (Cq),
138.2 (Cq), 135.3 (Cq), 128.9 (2 × CH), 128.3 (2 × CH), 128.1 (2 × CH), 126.7 (2 × CH), 116.8 (CH), 59.8 (CH2),
34.9 (CH2), 33.2 (CH2), 28.5 (CH2), 21.0 (CH3), 15.4 (CH3), 14.3 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
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ν
max = 2965, 2932, 1707, 1620, 1607, 1453, 1368, 1263, 1155, 1031, 829, 747, 697 cmꢀ1. HRꢀMS (ESI+) m/z
calculated for [C22H30NO2]+ = [M+NH4]+: 340.2271; found: 340.2272.
Ethylꢀ5ꢀ(3ꢀmethoxyphenyl)ꢀ3ꢀphenylpentꢀ2ꢀenoate (9i & 9i’): GPꢀ1 was carried out with NaH (192.4 mg, 4.8
mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13i (576.0 mg, 2.40 mmol) and dry THF (9 mL) for
ο
esters formation 9i and 9i’ at 65 C for 12 h. Purification of the crude material by silica gel column
chromatography (petroleum ether/ethyl acetate 100:0 to 96:4) furnished the esters 9i (305.2 mg, 41%) and 9i’
(357.3 mg, 48%) as colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13i) = 0.25,
Rf(9i) = 0.50, Rf(9i’) = 0.40, UV detection]. 1H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9i): δ = 7.52‒7.32
(m, 5H), 7.18 (dd, 1H, J = 7.8 and 7.8 Hz), 6.82 (d, 1H, J = 7.8 Hz), 6.77 (s, 1H), 6.73 (d, 1H, J = 7.8 Hz), 6.07
(s, 1H), 4.21 (q, 2H, J = 7.3 Hz), 3.79 (s, 3H), 3.41 (dd, 2H, J = 8.3 and 7.8 Hz), 2.72 (dd, 2H, J = 8.3 and 7.8
Hz), 1.31 (t, 3H, J = 7.3 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ=166.3 (Cq), 159.5 (Cq), 159.2 (Cq), 143.1 (Cq),
141.0 (Cq), 129.2 (CH), 129.0 (CH), 128.6 (2 × CH), 126.7 (2 × CH), 120.9 (CH), 117.9 (CH), 114.1 (CH), 111.3
(CH), 59.9 (CH2), 55.1 (CH3), 35.1 (CH2), 32.9 (CH2), 14.3 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1): νmax
=
2966, 2931, 1706, 1621, 1607, 1454, 1369, 1264, 1155, 1032, 748, 697 cmꢀ1. HRꢀMS (ESI+) m/z calculated for
[C20H22NaO3]+ = [M+Na]+: 333.1461; found: 333.1467.
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Ethylꢀ5ꢀ(3,4ꢀdimethoxyphenyl)ꢀ3ꢀphenylpentꢀ2ꢀenoate (9j & 9j’): GPꢀ1 was carried out with NaH (192.4 mg,
4.8 mmol), triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13j (648.2 mg, 2.40 mmol) and dry THF (9 mL) for
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esters formation 9j and 9j’ at 65 C for 12 h. Purification of the crude material by silica gel column
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chromatography (petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9j (293.9 mg, 36%) and 9j’
(359.2 mg, 44%) as colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 85:15), Rf(13j) =
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0.35, Rf(9j) = 0.55, Rf(9j’) = 0.50, UV detection]. H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9j): δ =
7.52‒7.30 (m, 5H), 6.80‒6.60 (m, 3H), 6.04 (s, 1H), 4.19 (q, 2H, J = 7.3 Hz), 3.85 (s, 3H), 3.84 (s, 3H), 3.40 (dd,
2H, J = 8.3 and 7.8 Hz), 2.68 (dd, 2H, J = 8.3 and 7.8 Hz), 1.30 (t, 3H, J = 7.3 Hz) ppm. 13C NMR (CDCl3, 100
MHz): δ=166.3 (Cq), 159.4 (Cq), 148.7 (Cq), 147.2 (Cq), 141.1 (Cq), 134.1 (Cq), 128.9 (CH), 128.5 (2 × CH),
126.7 (2 × CH), 120.3 (CH), 117.9 (CH), 111.8 (CH), 111.1 (CH), 59.8 (CH2), 55.9 (CH3), 55.8 (CH3), 34.6
(CH2), 32.9 (CH2), 14.3 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
νmax = 2965, 2930, 1707, 1620, 1606, 1453,
1368, 1264, 1154, 1110, 1031, 747, 696 cmꢀ1. HRꢀMS (ESI+) m/z calculated for [C21H24NaO4]+ = [M+Na]+:
363.1567; found: 363.1571.
Ethylꢀ5ꢀ(4ꢀnitrophenyl)ꢀ3ꢀphenylpentꢀ2ꢀenoate (9k): GPꢀ1 was carried out with NaH (192.4 mg, 4.8 mmol),
triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13k (612.2 mg, 2.40 mmol) and dry THF (9 mL) for ester
ο
formation 9k at 65 C for 12 h. Purification of the crude material by silica gel column chromatography
(petroleum ether/ethyl acetate 100:0 to 98:2) furnished the ester 9k (327.8 mg, 42%) as pale yellow semiꢀsolid.
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[TLC control (petroleum ether/ethyl acetate 85:15), Rf(13k) = 0.35, Rf(9k) = 0.55, UV detection]. H NMR
(CDCl3, 400 MHz): δ = 8.09 (d, 2H, J = 8.8 Hz), 7.45‒7.36 (m, 5H), 7.35 (d, 2H, J = 8.8 Hz), 6.07 (s, 1H), 4.18
(q, 2H, J = 7.3 Hz), 3.43 (dd, 2H, J = 7.8 and 7.8 Hz), 2.83 (dd, 2H, J = 7.8 and 7.8 Hz), 1.29 (t, 3H, J = 7.3 Hz)
ppm. 13C NMR (CDCl3, 100 MHz): δ=166.2 (Cq), 158.4 (Cq), 149.2 (Cq), 146.4 (Cq), 140.5 (Cq), 129.3 (2 × CH),
129.2 (CH), 128.7 (2 × CH), 126.6 (2 × CH), 123.5 (2 × CH), 118.4 (CH), 60.0 (CH2), 34.8 (CH2), 32.2 (CH2),
14.3 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
νmax = 2970, 2932, 1708, 1619, 1602, 1550, 1453, 1264, 1158,
1050, 1032, 746 cmꢀ1. HRꢀMS (ESI+) m/z calculated for [C19H20NO4]+=[M+H]+: 326.1387; found: 326.1379.
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Ethylꢀ3,6ꢀdiphenylhexꢀ2ꢀenoate (9l & 9l’): GPꢀ1 was carried out with NaH (192.4 mg, 4.8 mmol),
triethylphosphanoaetate (1.3 g, 5.8 mmol), ketone 13l (538.3 mg, 2.40 mmol) and dry THF (9 mL) for esters
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formation 9l and 9l’ at 65 C for 12 h. Purification of the crude material by silica gel column chromatography
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(petroleum ether/ethyl acetate 100:0 to 98:2) furnished the esters 9l (261.4 mg, 37%) and 9l’ (303.8 mg, 43%) as
colour less viscous liquids. [TLC control (petroleum ether/ethyl acetate 95:5), Rf(13l) = 0.35, Rf(9l) = 0.65, Rf(9l’)
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= 0.60, UV detection]. H NMR (CDCl3, 400 MHz, peaks due to Eꢀisomer 9l): δ = 7.40‒7.30 (m, 5H), 7.23 (dd,
2H, J = 7.8 and 7.3 Hz), 7.20‒7.08 (m, 3H), 6.04 (s, 1H), 4.20 (q, 2H, J = 7.3 Hz), 3.20–3.10 (m, 2H), 2.70–2.60
(m, 2H), 1.82–1.65 (m, 2H), 1.30 (t, 3H, J = 7.3 Hz) ppm. 13C NMR (CDCl3, 100 MHz): δ = 166.5 (Cq), 160.3
(Cq), 142.2 (Cq), 141.2 (Cq), 128.9 (CH), 128.5 (2 × CH), 128.4 (2 × CH), 128.2 (2 × CH), 126.7 (2 × CH), 125.7
(CH), 117.7 (CH), 59.9 (t, CH2), 35.9 (CH2), 30.7 (CH2), 30.6 (CH2), 14.3 (q, CH3) ppm. IR (MIRꢀATR, 4000–
600 cmꢀ1): max = 2979, 2931, 1709, 1623, 1494, 1451, 1368, 1157, 1042, 875, 749, 697 cmꢀ1. HRꢀMS (ESI+) m/z
ν
calculated for [C20H23O2]+=[M+H]+: 295.1693; found: 295.1694.
1ꢀMethylꢀ1ꢀphenylindane (10a): GPꢀ2 was carried out with ester 9a (140 mg, 0.50 mmol) and trifluroacetic acid
(3 mL) for indane formation at 80 °C for 24 h. Purification of the crude material by silica gel column
chromatography (petroleum ether/ethyl acetate 100:0 to 99:1) furnished the indane 10a (82.2 mg, 79%) as colour
less viscous liquid. [TLC control (petroleum ether/ethyl acetate 99:1), Rf(9a) = 0.30, Rf(10a) = 0.90, UV
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detection]. H NMR (CDCl3, 400 MHz): δ = 7.30‒7.00 (m, 9H), 3.00–2.75 (m, 2H), 2.45–2.32 (m, 1H), 2.25–
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2.10 (m, 1H), 1.66 (s, 3H) ppm. C NMR (CDCl3, 100 MHz): δ = 150.9 (Cq), 149.0 (Cq), 143.6 (Cq), 128.0 (2 ×
CH), 126.6 (2 × CH), 126.5 (CH), 126.4 (CH), 125.7 (CH), 124.5 (CH), 124.2 (CH), 52.0 (Cq), 44.1 (CH2), 30.4
(CH2), 27.4 (CH3) ppm. IR (MIRꢀATR, 4000–600 cmꢀ1):
763, 724 cmꢀ1.
νmax = 2961, 1492, 1479, 1454, 1372, 1096, 1012, 821,
1ꢀ(4ꢀChlorophenyl)ꢀ1ꢀmethylindane (10b): GPꢀ2 was carried out with ester 9b (157.4 mg, 0.50 mmol) and
trifluroacetic acid (3 mL) for indane formation at 80 °C for 12 h. Purification of the crude material by silica gel
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