Ring opening of DA-cyclopropanes with electron rich arene/heteroarene: Synthesis of 2-(2,2-diarylethyl)malonates

Article abstract of DOI:10.1016/j.tet.2015.12.001

An efficient strategy for nucleophilic ring opening of donor-acceptor (DA)-cyclopropanes with electron rich arenes to provide 2-(2,2-diarylethyl)malonates in excellent yields is described. The reaction was found to be successful with heteroarenes as the n

Full text of DOI:10.1016/j.tet.2015.12.001

Tetrahedron xxx (2015) 1e12
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Ring opening of DA-cyclopropanes with electron rich arene/
heteroarene: synthesis of 2-(2,2-diarylethyl)malonates
Ranadeep Talukdar, Amrita Saha, Deo Prakash Tiwari, Manas K. Ghorai *
Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient strategy for nucleophilic ring opening of donor-acceptor (DA)-cyclopropanes with electron
rich arenes to provide 2-(2,2-diarylethyl)malonates in excellent yields is described. The reaction was
found to be successful with heteroarenes as the nucleophile as well. Reaction of enantiopure DA-
cyclopropane with arene/heteroarene as the nucleophiles afforded the corresponding 2-(2,2-
diarylethyl)malonates with high yield and enantioselectivity (ee 95%). The synthetic utility of the
products was demonstrated by converting them easily into other important synthetic scaffolds like
functionalized cyclohexene and malonic acid derivatives.
Received 26 August 2015
Received in revised form 27 November 2015
Accepted 1 December 2015
Available online xxx
Keywords:
2-(2,2-Diarylethyl)malonates
Ó 2015 Elsevier Ltd. All rights reserved.
DA-cyclopropanes
Nucleophilic ring opening
Electron rich arene
Indole
1. Introduction
where only a limited variety of DA-cyclopropanes were utilized
along with neutral arene nucleophiles. However, there is no report
4
Donor-acceptor (DA)-cyclopropanes being proclaimed as ver-
satile building blocks have received considerable attention in
modern organic synthesis. During the last one decade, there has
been prolific expansion of synthetic utilities of these reactive three
for the synthesis of nonracemic 2-(2,2-diarylethyl)malonates via
ring opening of enantiopure DA-cyclopropane with neutral arenes.
It is worth mentioning that ring opening of DA-cyclopropanes e.g.,
2-arylcyclopropane-1,1-dicarboxylate with arenes can generate
2-(2,2-diaryl)ethyl malonates which can be converted into several
useful synthetic scaffolds upon further synthetic manipulations.
Hence further synthetic exploration to this field of DA-
cyclopropane chemistry is highly desirable.
1
membered carbacycles. Due to the presence of donor and acceptor
functionalities in the ring the intervening CeC bond becomes
weaker and furthermore, the interaction of the acceptor terminal
with a suitable Lewis acid (LA) catalyst makes this bond even more
labile. DA-cyclopropanes mostly tend to undergo two types of
In continuation of our research endeavor with DA-cyclopro-
2
5
synthetic transformations: 1) cycloaddition reactions and 2) ring
panes, we have developed an efficient strategy for the synthesis of
opening reactions.3 In the presence of a Lewis acid catalyst, DA-
cyclopropanes serve as a ‘masked or homo’ Michael acceptor
which can be intercepted by suitable nucleophiles to generate
a number of valuable organic compounds. A large variety of carbon
and heteroatomic nucleophiles, both neutral and anionic in nature,
have been employed for such synthetic transformations. Though
ring opening reactions with anionic nucleophiles are well docu-
mented in the literature, employment of neutral nucleophiles like
arenes and heteroarenes in the ring opening reactions of DA cy-
clopropanes is not much explored. There are a few reports on the
2-(2,2-diarylethyl)malonates via LA-catalyzed ring opening of DA-
cyclopropanes with arenes and heteroarenes. Herein, we report
our results in detail as an article.
2. Results and discussion
As a preliminary study, the reaction of DA-cyclopropane 1a with
1
(
,3,5-trimethoxybenzene 2a (1.5 equiv) in the presence of Yb(OTf)
20 mol %) as the LA catalyst (Table 1) in dichloromethane was
performed to provide the corresponding arylated product 3a in
excellent yield (entry 1, Table 1). Yb(OTf) was chosen as the LA
3
3
fei,4
reaction of DA-cyclopropanes with arenes and heteroarenes.
But to the best of our knowledge, only few reports are available
3
catalyst based on our earlier success with this Lewis acid in domino
ring opening cyclization (DROC) of DA-cyclopropanes for the syn-
5
thesis of several valuable synthetic targets. Surprisingly, when 1,2-
dichloroethane was used as the reaction medium, almost quanti-
tative yield of 3a was achieved (entry 2). In the presence of
*
Corresponding author. Tel.: þ91 512 2597518; fax: þ91 512 2596806; e-mail
address: mkghorai@iitk.ac.in (M.K. Ghorai).
http://dx.doi.org/10.1016/j.tet.2015.12.001
0
040-4020/Ó 2015 Elsevier Ltd. All rights reserved.
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2
R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
Table 1
Optimization study
Entry
Conditions
Time
Yield (%)
1
2
3
4
5
6
7
8
Yb(OTf)
Yb(OTf)
Yb(OTf)
3
3
3
(20 mol %), dichloromethane, rt
(20 mol %), 1,2-dichloroethane, rt
(1.0 equiv), 1,2-dichloroethane, rt
(20 mol %), 1,2-dichloroethane, rt-65
(20 mol %), 1,2-dichloroethane, rt-65
(20mol %), 1,2-dichloroethane, rt-65
(20mol %), 1,2-dichloroethane, rt-65
(20mol %), 1,2-dichloroethane, rt-65
5.0 h
7.0 h
2.0 h
75 min
25 min
45 min
6.0 h
2.0 h
30 min
6.0 h
86
99
96
99
75
92
85
22
53
45
a
ꢀ
C
C
Yb(OTf)
3
a
i
ꢀ
Ti(O Pr)
4
a
ꢀ
C
Sc(OTf)
Zn(OTf)
3
a
ꢀ
ꢀ
2
C
C
a
Cu(OTf)
AlCl
FeCl
2
a
ꢀ
ꢀ
9
1
3
(20 mol %), 1,2-dichloroethane, rt-65
(20 mol %), 1,2-dichloroethane, rt-65
C
C
0a
3
a
ꢀ
Addition was done at rt and then stirred for 75 min at 65 C.
stoichiometric amount of the Lewis acid, the reaction took shorter
time for complete consumption of 1a but the product 3a was ob-
Next, to extend the scope of our strategy further, 2-
heteroarylcyclopropane-1,1-dicarboxylates 1neo and 2-
tained with slightly reduced yield (entry 3). When the reaction was
styrylcyclopropane-1,1-dicarboxylates 1peq were reacted with
1,3,5-trimethoxybenzene under our reaction conditions (Schemes
2 and 3). Pleasingly, the corresponding products 3neq were ob-
tained in excellent yields in all these cases.
ꢀ
performed at 65 C in the presence of 20 mol % of Yb(OTf)
3
, it was
completed in 75 min providing 3a in 99% yield (entry 4). Other
i
Lewis acid catalysts e.g., Ti(O Pr)
4 3 2 2
, Sc(OTf) , Zn(OTf) , Cu(OTf) ,
AlCl and FeCl etc. could not provide better results. In all these
cases, either reaction took longer time for completion and/or 3a
was obtained with reduced yield (entry 5e10). So, we decided to
3
3
It is worth mentioning that in case of styryl substrates 1peq the
nucleophile exclusively attacked the C-2 position of the cyclopro-
pane ring and provided the corresponding products in excellent
0
proceed further using Yb(OTf)
dicloroethane as the solvent at 65 C as the optimum reaction
condition.
3
as the LA-catalyst and 1,2-
yields (Scheme 3). No product formation via S
nucleophile on the double bond was observed.
N
2 attack of the
ꢀ
Diaryl dicarboxylate 3p was converted into cyclohexene de-
rivative upon allylation of malonate group followed by ring closing
metathesis (Scheme 4). This type of cyclohexene ring system is very
close to a biologically active natural product (þ)-methyllinderatin,
To generalize our approach a number of substituted DA-
cyclopropanes (1bem) were studied under the optimized re-
action condition (Scheme 1) and the results are shown in Table 2. It
is important to mention that compounds bearing 1,3,5-
trimethoxybenzene or 1,3,5-trihydroxybenzene ring are found to
7
a potent antimalarial agent.
We also performed ring opening reactions of several substituted
DA-cyclopropanes with indoles as the heteroarenes under our re-
6
exhibit several interesting biological activities.
Scheme 1. Ring opening of DA-cyclopropanes with electron rich arene 2a.
When p-tolyl cyclopropane dicarboxylate 1b was reacted with
a, the corresponding product 3b was obtained in excellent yield
entry 2, Table 2). DA-cyclopropanes bearing electron-rich aryl
groups (1cef) behaved similarly generating the dicarboxylates
cef in excellent yields (entry 3e6). Halogenated substrates (1gej)
also smoothly converted into their corresponding products 3gej
upon reaction with 2a (entry 7e10). When 1-naphthyl substituted
DA-cyclopropane 1k was chosen as the substrate, the correspond-
ing dicarboxylate 3k was obtained in 80% yield (entry 11). 2-
naphthylcyclopropane-1,1-dicarboxylate 1l reacted in a similar
pattern generating 3l in excellent yield (entry 12). Similarly, when
action condition (Scheme 5) and the results are described in Table
3. When N-methyl indole 2b was reacted with 1a, the corre-
sponding dicarboxylate 3r was obtained in 95% yield. When p-
methoxy cyclopropane dicarboxylate 1c was reacted with 2b, the
corresponding product 3s was obtained in excellent yield. DA-
cyclopropane bearing styryl group behaved similarly generating
the dicarboxylate derivative 3t in high yield. DA-cyclopropane 1a
reacts with other substituted N-methyl indoles 2c,d to generate the
corresponding products 3u,v in excellent yields (Table 3).
Allylation of malonate group of diaryl dicarboxylate 3t followed
by ring closing metathesis gave the cyclohexene derivative 7 in
excellent yield (Scheme 6).
2
(
3
2
-mesitylcyclopropane-1,1-dicarboxylate 1m was reacted with
,3,5-trimethoxybenzene 2a, the corresponding product 3m was
obtained in 82% yield.
1
Reactions with other arene and heteroarene nucleophiles like
1,2-/1,4-dimethoxybenzene, 1,3-benzodioxole and thiophene etc.
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R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
3
Table 2
Scope of the reaction with DA-cyclopropanes with arene
(continued on next page)
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4
R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
Table 2 (continued)
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R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
5
Scheme 2. Synthesis of heteroaryl-substituted dicarboxylates.
Scheme 3. Reactivity of styryl cyclopropane dicarboxylates.
Scheme 4. Synthesis of 1,3,5-trimethoxy phenyl cyclohexene derivative.
Scheme 5. Ring opening of DA-cyclopropanes with indoles.
resulted in complicated reaction mixtures probably due to forma-
tion of regioisomers.
LA-coordinated cyclopropane in an S
matization generates the product 3. Reaction of DA-cyclopropane
N
2 fashion followed by aro-
In order to extend the synthetic utility of our protocol, the diaryl
diarboxylate products (3a, 3s) were hydrolyzed to the corre-
sponding malonic acids under reported conditions (Scheme 7). This
type of malonic acid derivatives can be converted to several im-
with heteroarenes follows similar reaction pathways.
3. Conclusion
8
portant compounds of synthetic and biological significance.
In conclusion, we have developed a simple and efficient protocol
To broaden the scope of our strategy, it was extended further for
the synthesis of nonracemic 2-(2,2-diarylethyl)malonates. When
enantiopure cyclopropane (S)-1a (ee >99%) was reacted with 1,3,5-
trimethoxybenzene 2a under our optimized condition, to our great
pleasure the corresponding nonracemic 2-(2,2-diarylethyl)malo-
nate product (R)-3a was obtained in high yield and high enantio-
meric excess (ee 95%). Similar reaction of (S)-1a with N-methyl
indole 2b afforded the nonracemic 2-(2,2-diarylethyl)malonate
product (R)-3r in high yield and high enantiomeric excess (ee 95%)
for the synthesis of highly functionalized 2-(2,2-diarylethyl)malo-
nates via LA-catalyzed ring opening of functionalized DA-
cyclopropanes with arene and heteroarenes. The synthetic signifi-
cance of the strategy was demonstrated by easy conversion of the
products into other important synthetic scaffolds like functional-
ized cyclohexene and malonic acid derivatives etc. Nonracemic
products with high enantioselectivity could be obtained employing
enantiopure cyclopropane as the substrate.
(
Scheme 8).
4
4
. Experimental section
The proposed mechanism of the reaction with DA-cyclopropane
and arene is depicted in Scheme 9. The Lewis acid interacts with
two ester moieties of the substrate 1 and the electrophilicity at the
C-2 position (often benzylic) of the DA-cyclopropane is enhanced.
Next the attack of the arene nucleophile at the C-2 position of the
.1. General experimental
Analytical thin layer chromatography (TLC) was carried out
using silica gel 60 F254 pre-coated plates. Visualization was
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6
R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
Table 3
Scope of the reaction with DA-cyclopropanes with indoles
accomplished with UV lamp or I
2
stain. Silica gel 230e400 mesh
atmosphere of nitrogen using anhydrous solvents. Where appro-
size was used for column chromatography using the combination of
ethyl acetate and petroleum ether as an eluent. Unless noted, all
reactions were carried out in oven-dried glassware under an
priate, solvents and all reagents were purified prior to use following
the guidelines of Perrin and Armarego and Vogel. All racemic 2-
arylcyclopropane-1,1-dicarboxylates were prepared using reported
9
10
Scheme 6. Synthesis of N-methyl indole cyclohexene derivative.
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R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
7
ꢀ
solvent. White solid (192 mg, yield 73%). Mp 55e57 C. R
f
0.35 (20%
ꢁ
1
EtOAc/hexanes). IR (KBr, cm ) 3003, 2954, 2838, 1727, 1607, 1577,
513, 1437, 1376, 1327, 1305, 1287, 1255, 1207, 1177, 1130, 1033, 964,
00, 853, 821, 768, 703. H NMR (500 MHz, CDCl ): d 7.24e7.21 (m,
3
1
9
2
1
H), 6.82 (dd, J¼6.7, 1.9 Hz, 2H), 6.57 (d, J¼15.8 Hz, 1H), 5.66 (dd,
J¼15.8, 8.6 Hz, 1H), 3.79 (s, 3H), 3.75 (s, 3H), 3.72 (s, 3H), 2.72 (q,
J¼8.6 Hz,1H),1.83 (dd, J¼7.6, 5.0 Hz,1H),1.67 (dd, J¼9.0, 5.0 Hz,1H).
13
1
3
C{ H} NMR (125 MHz, CDCl ): d 170.1, 168.1, 159.3, 133.4, 129.6,
1
27.4, 122.2, 114.1, 55.4, 52.9, 52.8, 36.1, 32.0, 21.4; HRMS (ESI-TOF)
Calcd for C16
H18NaO
5
(MþNa)þ 313.1052, found 313.1059.
4.3. General procedure for the synthesis of dialkyl (2-(2,2-
diaryl)ethyl)malonates 3aev
Scheme 7. Hydrolysis of diester 3 to malonic acid derivatives.
To
dichloroethane (DCE) (1.0 mL),
arylcyclopropane-1,1-dicarboxylate 1aeq (1.0 mmol) and the ap-
propriate arene/heteroarene (2.0 mmol) in dry 1,2-
a
suspension of Yb(OTf)
3
(0.2 mmol) in dry 1,2-
a
solution of dialkyl 2-
method.11 (S)-1a was synthesized following literature procedure.12
All commercial reagents were used as received. IR spectra were
recorded either in neat condition or in potassium bromide (KBr)
2
dichloroethane (2.0 mL) was added at room temperature under
ꢀ
N
2
atmosphere and the reaction mixture was heated to 65 C with
1
pellet. Proton nuclear magnetic resonance ( H NMR) spectra were
stirring for appropriate time. After complete consumption of the
starting material (monitored by TLC) the reaction was quenched
with water (2.0 mL). After separating the organic layer, the aqueous
layer was extracted with dichloromethane (4ꢂ2.0 mL). The com-
bined organic extract was washed with brine, dried over anhydrous
sodium sulfate and the solvent was removed under reduced pres-
sure. The crude concentrate was purified by flash column chro-
matography on silica gel (230e400 mesh) using ethyl acetate in
petroleum ether (20%) as the eluent to afford the pure products
recorded at 400 and 500 MHz. Chemical shifts were recorded in
1
parts per million (ppm,
d
) relative to tetramethyl silane (
d
0.00). H
NMR splitting patterns are designated as singlet (s), doublet (d),
double doublet (dd), triplet (t), quartet (q) or multiplet (m). Carbon
13
nuclear magnetic resonance ( C NMR) spectra were recorded at
25 MHz. Mass spectra (MS) were obtained using FAB and ESI mass
1
spectrometer (TOF). Melting point was determined using a hot
stage apparatus and are reported as uncorrected.
3aev as colorless thick liquids or white crystalline or yellowish
4
.2. Dimethyl (E)-2-(4-methoxystyryl)cyclopropane-1,1-
solid.
dicarboxylate (1q)
4.3.1. Dimethyl 2-(2-phenyl-2-(2,4,6-trimethoxyphenyl)ethyl)malo-
The compound was synthesized by reacting dimethyl (E)-2-(3-
4-methoxyphenyl)allylidene)malonate (250 mg, 0.905 mmol) and
nate (3a). The compound was synthesized by reacting dimethyl 2-
phenylcyclopropane-1,1-dicarboxylate 1a (50 mg, 0.213 mmol) and
1,3,5-trimethoxybenzene 2a (72 mg, 0.426 mmol) in presence of
(
trimethylsulphoxonium iodide (239 mg,1.086 mmol) in presence of
NaH (44 mg, 1.086 mmol) in 2.0 mL dry DMF following the litera-
3
catalytic amount of Yb(OTf) (26 mg, 0.043 mmol) in overall 3.0 mL
11
ture reported method. Purified with 3% ethyl acetate in hexane
dry DCE following the mentioned optimized reaction condition.
Scheme 8. Ring opening of enantiopure DA-cyclopropane with electron rich arene and heteroarene.
Scheme 9. Mechanism of the reaction between DA-cyclopropanes and arene.
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8
R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
Purified with 20% ethyl acetate in hexane solvent. Thick colorless
liquid (85 mg, yield 99%). R 0.31 (35% EtOAc/hexanes). IR (Neat,
cm ) 2952, 2841, 1753, 1734, 1606, 1591, 1494, 1454, 1436, 1418,
328, 1222, 1205, 1149, 1119, 1061, 1044, 950, 814. 1H NMR
400 MHz, CDCl ):
7.27 (d, J¼7.8 Hz, 2H), 7.21e7.17 (m, 2H), 7.09 (t,
2H), 4.87 (dd, J¼11.0, 5.5 Hz, 1H), 3.79 (s, 3H), 3.76 (s, 3H), 3.71 (s,
3H), 3.69 (s, 6H), 3.59 (s, 3H), 3.58 (s, 3H), 3.31 (dd, J¼8.6, 5.5 Hz,
f
ꢁ
1
13
1
1H), 2.86e2.80 (m, 1H), 2.60e2.55 (m, 1H). C{ H} NMR (125 MHz,
1
(
3
CDCl ): d 170.5, 170.1, 159.9, 159.7, 152.6, 147.2, 138.4, 122.8, 121.3,
3
d
111.4, 109.9, 91.2, 60.1, 55.7, 55.6, 55.3, 52.4, 52.3, 50.7, 31.9, 31.6;
J¼7.3 Hz, 1H), 6.08 (s, 2H), 4.60 (dd, J¼10.8, 5.7 Hz, 1H), 3.77 (s, 3H),
HRMS (ESI-TOF) Calcd for C24
485.1782.
H
30NaO
9
(MþNa)þ 485.1788, found
3
2
CDCl
.70 (s, 3H), 3.69 (s, 6H), 3.61 (s, 3H), 3.24 (dd, J¼9.2, 5.5 Hz, 1H),
13 1
.94e2.86 (m, 1H), 2.75e2.68 (m, 1H). C{ H} NMR (125 MHz,
): 170.4, 170.1, 160.1, 159.5, 144.5, 127.8, 127.7, 125.5, 111.4,
3
d
4.3.5. Dimethyl 2-(2-(2,4,6-trimethoxyphenyl)-2-(3,4,5-
trimethoxyphenyl)ethyl)malonate (3e). The compound was synthe-
sized by reacting dimethyl 2-(3,4,5-trimethoxyphenyl)cyclopro-
pane-1,1-dicarboxylate 1e (50 mg, 0.154 mmol) and 1,3,5-
trimethoxybenzene 2a (52 mg, 0.309 mmol) in presence of cata-
9
C
1.2, 55.7, 55.3, 52.5, 52.4, 50.8, 37.1, 31.1; HRMS (ESI-TOF) Calcd for
þ
22
H
26NaO
7
(MþNa) 425.1576, found 425.1574.
2
5
For (R)-3a: Optical rotation [
a
]
D
¼þ49.3 (c 0.142, CHCl
3
) for
a 95% ee sample. The enantiomeric excess was determined by chiral
HPLC analysis (CELLULOSE-2 column), HexaneeIsopropanol 95:5,
3
lytic amount of Yb(OTf) (19 mg, 0.031 mmol) in overall 3.0 mL dry
flow rate¼1.0 mL/min, t
R
(1)¼14.72 min (major), t
R
(2)¼18.63 min
DCE following the mentioned optimized reaction condition. Puri-
(
minor).
fied with 25% ethyl acetate in hexane solvent. Thick colorless liquid
ꢁ
1
(
71 mg, yield 93%). R
f
0.25 (35% EtOAc/hexanes). IR (Neat, cm
)
4
.3.2. Dimethyl 2-(2-p-tolyl-2-(2,4,6-trimethoxyphenyl)ethyl)malo-
2938, 2839, 1752, 1735, 1605, 1589, 1508, 1455, 1418, 1327, 1224,
1
nate (3b). The compound was synthesized by reacting dimethyl 2-
p-tolyl)cyclopropane-1,1-dicarboxylate 1b (50 mg, 0.201 mmol)
and 1,3,5-trimethoxybenzene 2a (67 mg, 0.402 mmol) in presence
of catalytic amount of Yb(OTf) (25 mg, 0.040 mmol) in overall
.0 mL dry DCE following the mentioned optimized reaction con-
dition. Purified with 20% ethyl acetate in hexane solvent. Thick
colorless liquid (79 mg, yield 95%). R 0.32 (35% EtOAc/hexanes). IR
KBr, cm ) 2924, 2852, 1752, 1734, 1605, 1590, 1513, 1492, 1454,
1205, 1150, 1125, 1039, 1011, 950, 816. H NMR (400 MHz, CDCl
6.55 (s, 2H), 6.10 (s, 2H), 4.53 (dd, J¼10.8, 5.7 Hz, 1H), 3.79 (s, 6H),
3.78 (s, 3H), 3.77 (s, 3H), 3.73 (s, 6H), 3.69 (s, 3H), 3.62 (s, 3H), 3.22
3
):
(
d
1
3
3
(dd, J¼9.6, 5.5 Hz, 1H), 2.91e2.84 (m, 1H), 2.70e2.63 (m, 1H).
C
1
3
3
{ H} NMR (125 MHz, CDCl ): d 170.4, 170.1, 160.1, 159.4, 152.6, 140.3,
136.0, 110.9, 105.1, 91.2, 60.9, 56.1, 55.7, 55.3, 52.5, 52.4, 50.8, 37.6,
31.7; HRMS (ESI-TOF) Calcd for C25
493.2074.
33
H O
10 (MþH)þ 493.2074, found
f
ꢁ1
(
1
1
435, 1417, 1326, 1221, 1204, 1148, 1118, 1062, 1040, 949, 812. H
NMR (400 MHz, CDCl ):
7.17 (d, J¼7.8 Hz, 2H), 7.01 (d, J¼8.3 Hz,
H), 6.08 (s, 2H), 4.56 (dd, J¼10.8, 5.7 Hz, 1H), 3.77 (s, 3H), 3.69 (s,
H), 3.61 (s, 3H), 3.23 (dd, J¼9.6, 5.5 Hz, 1H), 2.93e2.85 (m, 1H),
t
3
d
4.3.6. Dimethyl 2-(2-(4-( butyl)phenyl)-2-(2,4,6-trimethoxyphenyl)
ethyl)malonate (3f). The compound was synthesized by reacting
dimethyl 2-(4-(tert-butyl)phenyl)cyclopropane-1,1-dicarboxylate
1f (50 mg, 0.172 mmol) and 1,3,5-trimethoxybenzene 2a (58 mg,
2
9
2
d
13
1
3
.73e2.65 (m, 1H), 2.26 (s, 3H). C{ H} NMR (100 MHz, CDCl ):
170.4, 170.1, 160.0, 159.4, 141.4, 134.8, 128.5, 127.7, 111.5, 91.2, 55.7,
3
0.345 mmol) in presence of catalytic amount of Yb(OTf) (21 mg,
5
C
5.3, 52.5, 52.4, 50.8, 36.8, 31.3, 21.0; HRMS (ESI-TOF) Calcd for
0.035 mmol) in overall 3.0 mL dry DCE following the mentioned
optimized reaction condition. Purified with 20% ethyl acetate in
þ
23
H28NaO
7
(MþNa) 439.1733, found 439.1736.
f
hexane solvent. Thick colorless liquid (59 mg, yield 75%). R 0.36
ꢁ1
4.3.3. Dimethyl 2-(2-(4-methoxyphenyl)-2-(2,4,6-trimethoxyphenyl)
(35% EtOAc/hexanes). IR (Neat, cm ) 2954, 2925, 1753, 1736, 1606,
ethyl)malonate (3c). The compound was synthesized by reacting
dimethyl 2-(4-methoxyphenyl)cyclopropane-1,1-dicarboxylate 1c
1591, 1492, 1456,1435, 1417,1327, 1222, 1204,1149, 1119,1063, 1042,
1
950, 815. H NMR (400 MHz, CDCl
3
):
d
7.22 (s, 4H), 6.09 (s, 2H), 4.58
(
0
0
50 mg, 0.189 mmol) and 1,3,5-trimethoxybenzene 2a (64 mg,
(dd, J¼11.0, 6.0 Hz, 1H), 3.77 (s, 3H), 3.70 (s, 6H), 3.69 (s, 3H), 3.61 (s,
.378 mmol) in presence of catalytic amount of Yb(OTf)
3
(23 mg,
3H), 3.24 (dd, J¼9.6, 5.5 Hz, 1H), 2.96e2.88 (m, 1H), 2.74e2.67 (m,
13
1
.038 mmol) in overall 3.0 mL dry DCE following the mentioned
3
1H), 1.27 (s, 9H). C{ H} NMR (125 MHz, CDCl ): d 170.5, 170.1,
optimized reaction condition. Purified with 20% ethyl acetate in
hexane solvent. Thick colorless liquid (80 mg, yield 98%). R 0.30
35% EtOAc/hexanes). IR (Neat, cm ) 2924, 1733, 1605, 1511, 1456,
160.0, 159.5, 148.1, 141.3, 127.5, 124.7, 111.3, 91.1, 55.7, 55.3, 52.5,
f
35 7
52.4, 50.9, 36.8, 34.3, 31.5, 31.4; HRMS (ESI-TOF) Calcd for C26H O
ꢁ
1
(MþH)þ 459.2383, found 459.2383.
(
1
3
1245, 1204, 1148, 1118, 1035, 813. H NMR (400 MHz, CDCl ): d 7.21
(
6
d, J¼8.2 Hz, 2H), 6.77e6.74 (m, 2H), 6.09 (s, 2H), 4.55 (dd, J¼13.2,
4.3.7. Dimethyl
2-(2-(4-fluorophenyl)-2-(2,4,6-trimethoxyphenyl)
.0 Hz, 1H), 3.78 (s, 3H), 3.75 (s, 3H), 3.71 (s, 3H), 3.70 (s, 6H), 3.62
ethyl)malonate (3g). The compound was synthesized by reacting
dimethyl 2-(4-fluorophenyl)cyclopropane-1,1-dicarboxylate 1g
(50 mg, 0.198 mmol) and 1,3,5-trimethoxybenzene 2a (67 mg,
(
(
s, 3H), 3.24 (dd, J¼9.2, 5.5 Hz, 1H), 2.92e2.85 (m, 1H), 2.73e2.65
m, 1H). 13C{ H} NMR (125 MHz, CDCl
): d 170.4, 170.1, 160.0, 159.4,
3
1
1
3
4
57.5, 136.7, 128.7, 113.2, 111.7, 91.2, 55.7, 55.3, 55.2, 52.4, 52.3, 50.9,
3
0.396 mmol) in presence of catalytic amount of Yb(OTf) (25 mg,
0.040 mmol) in overall 3.0 mL dry DCE following the mentioned
optimized reaction condition. Purified with 20% ethyl acetate in
6.5, 31.5; HRMS (ESI-TOF) Calcd for
55.1682, found 455.1669.
C
23
H28NaO
8
(MþNa)þ
f
hexane solvent. Thick colorless liquid (80 mg, yield 96%). R 0.32
ꢁ1
4
.3.4. Dimethyl 2-(2-(2,3-dimethoxyphenyl)-2-(2,4,6-
(35% EtOAc/hexanes). IR (Neat, cm ) 2953, 2842, 1753, 1734, 1606,
trimethoxyphenyl)ethyl)malonate (3d). The compound was syn-
thesized by reacting dimethyl 2-(2,3-dimethoxyphenyl)cyclopro-
pane-1,1-dicarboxylate 1d (50 mg, 0.170 mmol) and 1,3,5-
trimethoxybenzene 2a (57 mg, 0.340 mmol) in presence of cata-
1508,1494, 1455,1436,1418,1326,1221,1205,1150,1119,1063,1041,
1
1016, 950, 816, 797. H NMR (500 MHz, CDCl
3
):
d
7.23 (dd, J¼8.6,
5.5 Hz, 2H), 6.88 (t, J¼8.9 Hz, 2H), 6.09 (s, 2H), 4.57 (dd, J¼11.0,
5.5 Hz, 1H), 3.78 (s, 3H), 3.70 (s, 3H), 3.69 (s, 6H), 3.61 (s, 3H), 3.22
1
3
lytic amount of Yb(OTf)
3
(21 mg, 0.034 mmol) in overall 3.0 mL dry
(dd, J¼9.2, 5.5 Hz, 1H), 2.90e2.84 (m, 1H), 2.71e2.65 (m, 1H).
C
1
DCE following the mentioned optimized reaction condition. Puri-
{ H} NMR (125 MHz, CDCl
3
):
d
170.3, 170.0, 161.0 (d, JCeF¼241 Hz),
fied with 20% ethyl acetate in hexane solvent. Thick colorless liquid
160.2, 159.3, 140.2, 129.2, 129.1, 114.5, 114.3, 111.2, 91.2, 55.6, 55.3,
ꢁ1
(
71 mg, yield 90%). R
f
0.28 (35% EtOAc/hexanes). IR (KBr, cm
)
52.5, 52.4, 50.7, 36.4, 31.2; HRMS (ESI-TOF) Calcd for C22H25NaFO
7
3
004, 2937, 2840, 1734, 1605, 1590, 1494, 1463, 1420, 1326, 1275,
(MþNa)þ 443.1482, found 443.1485.
1
8
218, 1205, 1189, 1151, 1121, 1097, 1065, 1046, 1008, 952, 929, 897,
1
31, 814, 794, 752, 710. H NMR (500 MHz, CDCl
3
):
d
7.05 (d,
4.3.8. Dimethyl 2-(2-(4-chlorophenyl)-2-(2,4,6-trimethoxyphenyl)
J¼8.0 Hz, 1H), 6.95 (t, J¼8.0 Hz, 1H), 6.72 (d, J¼8.0 Hz, 1H), 6.07 (s,
ethyl)malonate (3h). The compound was synthesized by reacting
Please cite this article in press as: Talukdar, R.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.12.001

R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
9
dimethyl 2-(4-chlorophenyl)cyclopropane-1,1-dicarboxylate 1h
50 mg, 0.186 mmol) and 1,3,5-trimethoxybenzene 2a (67 mg,
3.39 (dd, J¼9.2, 5.0 Hz, 1H), 3.07e3.00 (m, 1H), 2.81e2.74 (m, 1H).
3 1
1
(
C{ H} NMR (100 MHz, CDCl
3
): d 170.5, 170.1, 160.1, 159.5, 140.0,
0
.372 mmol) in presence of catalytic amount of Yb(OTf)
3
(23 mg,
133.8, 132.4, 128.6, 126.4, 125.6, 125.0, 124.9, 124.2, 111.1, 91.4, 55.6,
0
.037 mmol) in overall 3.0 mL dry DCE following the mentioned
55.3, 52.5, 50.6, 34.0, 32.0; HRMS (ESI-TOF) Calcd for C26H28NaO
7
optimized reaction condition. Purified with 20% ethyl acetate in
hexane solvent. Thick colorless liquid (73 mg, yield 88%). R 0.31
35% EtOAc/hexanes). IR (Neat, cm ) 2925, 2850, 1752, 1735, 1607,
591, 1491, 1456, 1435, 1418, 1325, 1222, 1205, 1149, 1119,1091, 1062,
(MþNa)þ 475.1733, found 475.1732.
f
ꢁ1
(
1
4.3.12. Dimethyl 2-(2-(naphthalen-2-yl)-2-(2,4,6-trimethoxyphenyl)
ethyl)malonate (3l). The compound was synthesized by reacting
dimethyl 2-(naphthalen-2-yl)cyclopropane-1,1-dicarboxylate 1l
(50 mg, 0.176 mmol) and 1,3,5-trimethoxybenzene 2a (59 mg,
0.352 mmol) in presence of catalytic amount of Yb(OTf) (22 mg,
3
0.035 mmol) in overall 3.0 mL dry DCE following the mentioned
1
1041, 1014, 950, 815. H NMR (500 MHz, CDCl
3
):
d
7.20 (d, J¼8.6 Hz,
2
3
5
H), 7.17e7.14 (m, 2H), 6.08 (s, 2H), 4.56 (dd, J¼10.9, 5.7 Hz, 1H),
.78 (s, 3H), 3.70 (s, 3H), 3.69 (s, 6H), 3.61 (s, 3H), 3.21 (dd, J¼9.2,
13
1
.2 Hz, 1H), 2.89e2.83 (m, 1H), 2.70e2.64 (m, 1H). C{ H} NMR
(
125 MHz, CDCl
3
):
d
170.3, 170.0, 160.3, 159.3, 143.1, 131.0, 129.2,
optimized reaction condition. Purified with 20% ethyl acetate in
1
27.8, 110.9, 91.2, 55.6, 55.3, 52.5, 52.4, 50.7, 36.5, 30.9; HRMS (ESI-
hexane solvent. Thick colorless liquid (71 mg, yield 89%). R
(35% EtOAc/hexanes). IR (Neat, cm ) 2999, 2952, 2841, 1752, 1734,
f
0.31
(MþNa)þ 459.1187, found 459.1187.
ꢁ1
TOF) Calcd for C22
H
25NaClO
7
1
606, 1591, 1493, 1454, 1435, 1418, 1331, 1261, 1224, 1205, 1149, 1118,
1
4.3.9. Dimethyl 2-(2-(4-bromophenyl)-2-(2,4,6-trimethoxyphenyl)
3
1063, 1040, 950, 855, 817, 746. H NMR (400 MHz, CDCl ):
ethyl)malonate (3i). The compound was synthesized by reacting
dimethyl 2-(4-bromophenyl)cyclopropane-1,1-dicarboxylate 1i
d
7.77e7.72 (m, 3H), 7.65 (d, J¼8.2 Hz, 1H), 7.42e7.34 (m, 3H), 6.10
(s, 2H), 4.76 (dd, J¼10.8, 5.3 Hz,1H), 3.78 (s, 3H), 3.71 (s, 3H), 3.69 (s,
6H), 3.63 (s, 3H), 3.30 (dd, J¼9.2, 5.5 Hz, 1H), 3.04e2.97 (m, 1H),
(
50 mg, 0.160 mmol) and 1,3,5-trimethoxybenzene 2a (54 mg,
1
3
1
0
.320 mmol) in presence of catalytic amount of Yb(OTf)
3
(20 mg,
3
2.89e2.81 (m, 1H). C{ H} NMR (100 MHz, CDCl ): d 170.4, 170.1,
0
.032 mmol) in overall 3.0 mL dry DCE following the mentioned
160.2,159.5,142.0,133.4, 131.9, 127.8,127.5,127.2,127.1, 125.6,125.5,
125.0, 111.2, 91.2, 55.7, 55.3, 52.5, 52.4, 50.8, 37.2, 31.0; HRMS (ESI-
optimized reaction condition. Purified with 20% ethyl acetate in
hexane solvent. Thick colorless liquid (69 mg, yield 90%). R 0.30
35% EtOAc/hexanes). IR (Neat, cm ) 2927, 2841, 1734, 1607, 1591,
488,1455,1435,1418,1326,1222,1204,1149,1119,1062,1041,1010,
TOF) Calcd for C26H28NaO
7
(MþNa)þ 475.1733, found 475.1736.
f
ꢁ1
(
1
4.3.13. Dimethyl 2-(2-mesityl-2-(2,4,6-trimethoxyphenyl)ethyl)mal-
onate (3m). The compound was synthesized by reacting dimethyl
2-mesitylcyclopropane-1,1-dicarboxylate 1m (50 mg, 0.181 mmol)
and 1,3,5-trimethoxybenzene 2a (61 mg, 0.362 mmol) in presence
of catalytic amount of Yb(OTf) (23 mg, 0.036 mmol) in overall
3
3.0 mL dry DCE following the mentioned optimized reaction con-
1
9
50, 814. H NMR (500 MHz, CDCl
3
):
d
7.31 (d, J¼8.0 Hz, 2H), 7.14 (d,
J¼8.1 Hz, 2H), 6.08 (s, 2H), 4.55 (dd, J¼10.9, 5.2 Hz, 1H), 3.78 (s, 3H),
3
2
CDCl
.70 (s, 3H), 3.69 (s, 6H), 3.61 (s, 3H), 3.21 (dd, J¼9.5, 5.5 Hz, 1H),
13 1
.88e2.82 (m, 1H), 2.70e2.64 (m, 1H). C{ H} NMR (125 MHz,
): 170.3, 170.0, 160.3, 159.3, 143.6, 130.7, 129.6, 119.2, 110.7,
3
d
9
C
1.1, 55.6, 55.3, 52.5, 52.4, 50.6, 36.6, 30.8; HRMS (ESI-TOF) Calcd for
dition. Purified with 20% ethyl acetate in hexane solvent. Thick
(MþNa)þ 503.0681, found 503.0689.
colorless liquid (66 mg, yield 82%). R
0.35 (35% EtOAc/hexanes). IR
22
H25NaBrO
7
f
ꢁ
1
(KBr, cm ) 2998, 2953, 2840, 1752, 1735, 1607, 1589, 1454, 1436,
1
4.3.10. Dimethyl 2-(2-(3-bromophenyl)-2-(2,4,6-trimethoxyphenyl)
1417, 1327, 1205, 1150, 1122, 1068, 1037, 952, 918, 852, 814, 739. H
NMR (400 MHz, CDCl ):
ethyl)malonate (3j). The compound was synthesized by reacting
dimethyl 2-(3-bromophenyl)cyclopropane-1,1-dicarboxylate 1j
3
d
6.71 (s, 2H), 6.07 (s, 2H), 4.62 (dd, J¼12.8,
4.6 Hz, 1H), 3.77 (s, 3H), 3.70 (s, 3H), 3.69 (s, 3H), 3.65 (s, 6H), 3.54
(
0
50 mg, 0.160 mmol) and 1,3,5-trimethoxybenzene (54 mg,
(dd, J¼10.8, 2.5 Hz, 1H), 3.06 (td, J¼13.5, 2.6 Hz, 1H), 2.24 (s, 6H),
13
1
.320 mmol) in presence of catalytic amount of Yb(OTf)
3
(20 mg,
3
2.18 (s, 3H), 2.21e2.13 (m, 1H). C{ H} NMR (125 MHz, CDCl ):
0
.032 mmol) in overall 3.0 mL dry DCE following the mentioned
d
170.6, 159.9, 159.7, 139.5, 136.8, 134.6, 129.9, 109.6, 91.0, 55.4, 55.3,
optimized reaction condition. Purified with 20% ethyl acetate in
hexane solvent. Thick colorless liquid (70 mg, yield 91%). R 0.33
35% EtOAc/hexanes). IR (Neat, cm ) 2925, 2853, 1730, 1594, 1493,
471, 1442, 1417, 1343, 1311, 1283, 1264, 1223, 1206, 1164, 1152, 1121,
52.4, 52.3, 50.6, 36.9, 32.1, 20.7, 20.2; HRMS (ESI-TOF) Calcd for
(MþH)þ 445.2226, found 445.2228.
f
C
25
33
H O
7
ꢁ
1
(
1
4.3.14. Dimethyl 2-(2-(furan-2-yl)-2-(2,4,6-trimethoxyphenyl)ethyl)
malonate (3n). The compound was synthesized by reacting di-
methyl 2-(furan-2-yl)cyclopropane-1,1-dicarboxylate 1n (50 mg,
0.223 mmol) and 1,3,5-trimethoxybenzene 2a (75 mg, 0.446 mmol)
in presence of catalytic amount of Yb(OTf) (28 mg, 0.045 mmol) in
3
overall 3.0 mL dry DCE following the mentioned optimized reaction
1
1075, 1062, 1031, 989, 894, 860, 814, 795, 783, 704. H NMR
(
400 MHz, CDCl ): 7.42e7.41 (m, 1H), 7.23e7.18 (m, 2H), 7.06 (t,
3
d
J¼7.8 Hz, 1H), 6.08 (s, 2H), 4.56 (dd, J¼11.2, 5.3 Hz, 1H), 3.78 (s, 3H),
3
2
CDCl
.71 (s, 3H), 3.69 (s, 6H), 3.61 (s, 3H), 3.20 (dd, J¼9.6, 5.5 Hz, 1H),
13
1
.89e2.82 (m, 1H), 2.69e2.62 (m, 1H). C{ H} NMR (100 MHz,
): 170.2, 169.9, 160.3, 159.3, 147.0, 130.9, 129.3, 128.5, 126.5,
3
d
condition. Purified with 20% ethyl acetate in hexane solvent. White
ꢀ
1
21.9, 110.5, 91.1, 55.6, 55.3, 52.5, 52.4, 50.6, 36.8, 30.8; HRMS (ESI-
crystalline solid (75 mg, yield 86%). Mp 86e88 C. R
f
0.34 (35%
(MþNa)þ 503.0681, found 503.0689.
EtOAc/hexanes). IR (KBr, cm ) 2953, 2840, 1735, 1607, 1592, 1496,
ꢁ1
TOF) Calcd for C22
H25NaBrO
7
1
458, 1437, 1419, 1326, 1222, 1205, 1151, 1119, 1061, 1040, 1011, 950,
1
4.3.11. Dimethyl 2-(2-(naphthalen-1-yl)-2-(2,4,6-trimethoxyphenyl)
917, 817, 733. H NMR (400 MHz, CDCl
3
):
d
7.21 (dd, J¼1.4 Hz, 1H),
ethyl)malonate (3k). The compound was synthesized by reacting
dimethyl 2-(naphthalen-1-yl)cyclopropane-1,1-dicarboxylate 1k
6.23 (dd, J¼3.2, 1.8 Hz, 1H), 6.09 (s, 2H), 5.98 (d, J¼3.2 Hz, 1H), 4.61
(t, J¼8.0 Hz, 1H), 3.78 (s, 3H), 3.71 (s, 3H), 3.69 (s, 6H), 3.59 (s, 3H),
13
1
(
50 mg, 0.176 mmol) and 1,3,5-trimethoxybenzene 2a (59 mg,
3.26 (d, J¼7.4 Hz,1H), 2.72 (d, J¼7.7 Hz,1H). C{ H} NMR (100 MHz,
0
.352 mmol) in presence of catalytic amount of Yb(OTf)
3
(22 mg,
3
CDCl ): d 170.2, 169.8, 160.4, 159.6, 157.8, 140.2, 110.0, 108.5, 104.2,
0
.035 mmol) in overall 3.0 mL dry DCE following the mentioned
91.2, 55.8, 55.3, 52.5, 52.4, 50.3, 32.0, 30.2; HRMS (ESI-TOF) Calcd
optimized reaction condition. Purified with 20% ethyl acetate in
hexane solvent. Thick colorless liquid (64 mg, yield 80%). R 0.34
35% EtOAc/hexanes). IR (Neat, cm ) 2952, 2840, 1751, 1733, 1606,
492, 1454, 1435, 1418, 1331, 1223, 1205, 1148, 1118, 1061, 1035, 950,
for C20H24NaO
8
(MþNa)þ 415.1369, found 415.1360.
f
ꢁ
1
(
1
4.3.15. Dimethyl
2-(2-(thiophen-2-yl)-2-(2,4,6-trimethoxyphenyl)
ethyl)malonate (3o). The compound was synthesized by reacting
dimethyl 2-(thiophen-2-yl)cyclopropane-1,1-dicarboxylate 1o
(50 mg, 0.208 mmol) and 1,3,5-trimethoxybenzene 2a (70 mg,
1
7
81. H NMR (400 MHz, CDCl
3
): d 8.22e8.20 (m, 1H), 7.78e7.76 (m,
1
H), 7.67e7.63 (m, 2H), 7.43e7.25 (m, 3H), 6.07 (s, 2H), 5.26 (dd,
J¼11.5, 4.6 Hz,1H), 3.75 (s, 3H), 3.74 (s, 3H), 3.69 (s, 6H), 3.60 (s, 3H),
3
0.416 mmol) in presence of catalytic amount of Yb(OTf) (26 mg,
Please cite this article in press as: Talukdar, R.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.12.001

10
R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
0
.042 mmol) in overall 3.0 mL dry DCE following the mentioned
optimized reaction condition. Purified with 20% ethyl acetate in
hexane solvent. Thick colorless liquid (71 mg, yield 84%). R 0.33
35% EtOAc/hexanes). IR (Neat, cm ) 2954, 2925, 2854, 1732, 1606,
590, 1494, 1456, 1418, 1323, 1204, 1149, 1118, 1062, 1037, 950, 815.
121.8, 119.6, 119.0, 117.3, 109.2, 52.6, 52.5, 50.2, 40.7, 35.1, 32.8;
þ
HRMS (EI-TOF) Calcd for C22
For (R)-3r: Optical rotation [
a 95% ee sample. The enantiomeric excess was determined by chiral
H23NO (M) 365.1627, found 365.1623.
4
2
5
f
a
]
D
¼ꢁ14.7 (c 0.102, CHCl
3
) for
ꢁ
1
(
1
HPLC analysis (OD-H column), HexaneeIsopropanol 95:5, flow
1
H NMR (400 MHz, CDCl
3
):
d
7.03 (dd, J¼5.04,1.4 Hz, 1H), 6.85e6.82
rate¼1.0 mL/min, t
R
(1)¼13.81 min (minor), t
R
(2)¼20.10 min
(
m, 2H), 6.09 (s, 2H), 4.83 (dd, J¼10.3, 6.2 Hz, 1H), 3.78 (s, 3H), 3.73
(major).
(
s, 6H), 3.69 (s, 3H), 3.62 (s, 3H), 3.23 (dd, J¼9.4, 5.7 Hz, 1H),
13
1
2
.92e2.85 (m, 1H), 2.78e2.71 (m, 1H). C{ H} NMR (125 MHz,
4.3.19. Dimethyl 2-(2-(4-methoxyphenyl)-2-(1-methyl-1H-indol-3-
yl)ethyl)malonate (3s). The compound was synthesized by react-
ing dimethyl 2-(4-methoxyphenyl)cyclopropane-1,1-dicarboxylate
3
CDCl ): d 170.2, 169.8, 160.4, 159.4, 148.7, 126.0, 123.7, 122.8, 110.7,
91.1, 55.7, 55.3, 52.5, 52.4, 50.6, 33.6, 32.9; HRMS (ESI-TOF) Calcd for
þ
C
20
H
24NaO
7
S (MþNa) 431.1140, found 431.1147.
1c (50 mg, 0.189 mmol) and 1-methylindole 2b (50
mL,
0
.378 mmol) in presence of catalytic amount of Yb(OTf) (24 mg,
3
4
.3.16. Dimethyl (E)-2-(4-phenyl-2-(2,4,6-trimethoxyphenyl)but-3-
0.038 mmol) in overall 3.0 mL dry DCE following the mentioned
enyl)malonate (3p). The compound was synthesized by reacting
dimethyl (E)-2-styrylcyclopropane-1,1-dicarboxylate 1p (50 mg,
optimized reaction condition. Purified with 20% ethyl acetate in
f
hexane solvent. Thick colorless liquid (74 mg, yield 97%). R 0.34 (35%
ꢁ
1
0
.192 mmol) and 1,3,5-trimethoxybenzene 2a (65 mg, 0.384 mmol)
EtOAc/hexanes). IR (Neat, cm ) 2953, 2926, 2854, 1732, 1610, 1583,
1
in presence of catalytic amount of Yb(OTf) (24 mg, 0.038 mmol) in
3
1547, 1511, 1435, 1373, 1327, 1247, 1153, 1034, 807, 742. H NMR
overall 3.0 mL dry DCE following the mentioned optimized reaction
3
(400 MHz, CDCl ): d 7.44e7.42 (m,1H), 7.26e7.15 (m, 4H), 7.03e6.99
condition. Purified with 20% ethyl acetate in hexane solvent. Thick
(m, 1H), 6.85e6.80 (m, 3H), 4.16e4.12 (m, 1H), 3.76 (s, 3H), 3.73 (s,
3H), 3.72 (s, 3H), 3.66 (s, 3H), 3.39 (dd, J¼8.5, 6.6 Hz, 1H), 2.83e2.76
colorless liquid (74 mg, yield 90%). R
f
0.34 (35% EtOAc/hexanes). IR
ꢁ1
13
1
(
Neat, cm ) 2951, 2840, 1733, 1590, 1492, 1453, 1435, 1330, 1218,
3
(m, 1H), 2.59e2.52 (m, 1H). C{ H} NMR (100 MHz, CDCl ): d 170.1,
1
1203, 1147, 1118, 1060, 1038, 966, 949, 812, 742. H NMR (500 MHz,
170.0, 158.2, 137.4, 135.6, 129.0, 127.2, 126.1, 121.8, 119.7, 118.9, 117.7,
114.0, 109.2, 55.3, 52.6, 52.5, 50.2, 39.9, 35.2, 32.8; HRMS (ESI-TOF)
CDCl ): 7.32e7.31 (m, 2H), 7.26e7.23 (m, 2H), 7.16e7.13 (m, 1H),
3
d
6
.59 (dd, J¼15.8, 8.3 Hz, 1H), 6.38 (d, J¼16.0 Hz, 1H), 6.11 (s, 2H),
Calcd for C23
H
25NaNO
5
(MþNa)þ 418.1630, found 418.1631.
4
.12e4.07 (m, 1H), 3.79 (s, 9H), 3.68 (s, 3H), 3.63 (s, 3H), 3.27 (dd,
13
1
J¼8.1, 6.3 Hz, 1H), 2.51e2.47 (m, 2H). C{ H} NMR (125 MHz,
CDCl ): 170.3, 170.1, 160.0, 159.2, 138.1, 132.5, 129.7, 128.4, 126.8,
4.3.20. Dimethyl (E)-2-(2-(1-methyl-1H-indol-3-yl)-4-phenylbut-3-
en-1-yl)malonate (3t). The compound was synthesized by react-
ing dimethyl (E)-2-styrylcyclopropane-1,1-dicarboxylate 1p
3
d
1
26.2, 110.9, 91.2, 55.8, 55.4, 52.5, 52.4, 50.6, 36.8, 32.5; HRMS (ESI-
TOF) Calcd for C24
H28NaO
7
(MþNa)þ 451.1733, found 451.1735.
(50 mg, 0.192 mmol) and 1-methylindole 2b (47
mL, 0.384 mmol) in
presence of catalytic amount of Yb(OTf) (24 mg, 0.038 mmol) in
3
4
.3.17. Dimethyl (E)-2-(4-(4-methoxyphenyl)-2-(2,4,6-
overall 3.0 mL dry DCE following the mentioned optimized reaction
trimethoxyphenyl)but-3-en-1-yl)malonate (3q). The compound
was synthesized by reacting dimethyl (E)-2-(4-methoxystyryl)cy-
clopropane-1,1-dicarboxylate 1q (50 mg, 0.172 mmol) and 1,3,5-
trimethoxybenzene 2a (58 mg, 0.344 mmol) in presence of cata-
condition. Purified with 9% ethyl acetate in hexane solvent. Thick
f
colorless liquid (70 mg, yield 93%). R 0.45 (20% EtOAc/hexanes). IR
ꢁ1
(Neat, cm ) 3055, 3025, 2952, 2925, 2853, 1751, 1733, 1614, 1599,
1546, 1484, 1469, 1448, 1435, 1374, 1328, 1268, 1254, 1225, 1154,
1
lytic amount of Yb(OTf)
3
(21 mg, 0.034 mmol) in overall 3.0 mL dry
1104, 1071, 1042, 1014, 968, 909, 841, 810, 743. H NMR (400 MHz,
DCE following the mentioned optimized reaction condition. Puri-
CDCl
3
):
d
7.68 (d, J¼8.0 Hz, 1H), 7.38e7.19 (m, 5H), 7.13e7.09 (m,
fied with 20% ethyl acetate in hexane solvent. Thick colorless liquid
1H), 6.93 (s, 1H), 6.55 (d, J¼15.8 Hz, 1H), 6.37 (dd, J¼16.0, 8.0 Hz,
ꢁ1
(
70 mg, yield 89%). R
f
0.35 (35% EtOAc/hexanes). IR (Neat, cm
)
1H), 3.82e3.74 (m, 1H), 3.76 (s, 3H), 3.72 (s, 3H), 3.69 (s, 3H), 3.56 (t,
13
1
2
999, 2952, 2838, 1752, 1734, 1607, 1511, 1493, 1454, 1438, 1419,
J¼7.3 Hz, 1H), 2.66e2.59 (m, 1H), 2.54e2.46 (m, 1H). C{ H} NMR
(125 MHz, CDCl ): 170.1, 170.0, 137.4, 132.4, 130.4, 128.6, 128.4,
127.3, 127.1, 126.4, 126.0, 121.9, 119.7, 119.1, 115.9, 109.4, 52.6, 50.2,
38.8, 34.3, 32.8; HRMS (ESI-TOF) Calcd for C24
414.1700, found 414.1682.
1
1
331,1249,1220,1204,1175,1149,1120,1060,1036, 969, 951, 815. H
NMR (400 MHz, CDCl ):
7.24 (d, J¼8.0 Hz, 2H), 6.78 (d, J¼8.7 Hz,
H), 6.45 (dd, J¼14.4, 8.3 Hz, 1H), 6.32 (d, J¼15.8 Hz, 1H), 6.10 (s,
H), 4.05 (q, J¼8.0 Hz, 1H), 3.78 (s, 9H), 3.77 (s, 3H), 3.67 (s, 3H),
3
d
3
d
2
2
3
H
25NNaO
4
(MþNa)þ
13
1
.62 (s, 3H), 3.26 (t, J¼7.7 Hz, 1H), 2.46 (t, J¼7.7 Hz, 2H). C{ H}
NMR (100 MHz, CDCl
3
): d 170.3, 170.2, 159.9, 159.1, 158.6, 130.9,
4.3.21. Dimethyl 2-(2-(4-bromo-1-methyl-1H-indol-3-yl)-2-
phenylethyl)malonate (3u). The compound was synthesized by
reacting dimethyl 2-phenylcyclopropane-1,1-dicarboxylate 1a
(50 mg, 0.213 mmol) and 4-bromo-1-methyl-1H-indole 2c (90 mg,
1
3
4
30.3, 129.1, 127.3, 113.8, 111.1, 91.1, 55.8, 55.4, 55.3, 52.5, 52.4, 50.7,
6.8, 32.6; HRMS (ESI-TOF) Calcd for
81.1838, found 481.1832.
C
25
H30NaO
8
(MþNa)þ
3
0.427 mmol) in presence of catalytic amount of Yb(OTf) (27 mg,
4.3.18. Dimethyl 2-(2-(1-methyl-1H-indol-3-yl)-2-phenylethyl)mal-
0.043 mmol) in overall 3.0 mL dry DCE following the mentioned
onate (3r). The compound was synthesized by reacting dimethyl 2-
phenylcyclopropane-1,1-dicarboxylate 1a (50 mg, 0.213 mmol) and
optimized reaction condition. Purified with 18% ethyl acetate in
f
hexane solvent. Thick colorless liquid (89 mg, yield 94%). R 0.42
ꢁ1
1
-methylindole 2b (53
mL, 0.427 mmol) in presence of catalytic
(35% EtOAc/hexanes). IR (Neat, cm ) 3059, 3027, 2952, 2854, 1751,
1734, 1606, 1550, 1492, 1478, 1451, 1435, 1418, 1330, 1276, 1228,
amount of Yb(OTf) (26 mg, 0.043 mmol) in overall 3.0 mL dry DCE
3
1
following the mentioned optimized reaction condition. Purified
1189, 1153, 1086, 1022, 908, 839, 770, 738, 703. H NMR (400 MHz,
with 15% ethyl acetate in hexane solvent. Yellowish solid (74 mg,
CDCl
3
):
d
7.33e7.13 (m, 6H), 7.02e6.97 (m, 2H), 5.10 (t, J¼7.9 Hz,1H),
ꢀ
yield 95%). Mp 90e92 C. R
cm ) 3026, 2926, 2952, 1751, 1734, 1601, 1547, 1471, 1435, 1374,
f
0.50 (35% EtOAc/hexanes). IR (Neat,
3.74 (s, 3H), 3.70 (s, 3H), 3.65 (s, 3H), 3.52e3.48 (m, 1H), 2.70e2.62
(m, 2H). C{ H} NMR (100 MHz, CDCl
128.4, 128.3, 128.1, 126.3, 125.2, 124.1, 122.5, 117.9, 114.3, 108.7, 52.6,
ꢁ
1
13
1
3
): d 170.1, 169.9, 144.5, 138.4,
1
1
(
329, 1279, 1259, 1226, 1153, 1042, 1014, 809, 742, 704. H NMR
400 MHz, CDCl ):
7.44 (d, J¼8.2 Hz, 1H), 7.32e7.25 (m, 5H),
.20e7.15 (m, 2H), 7.03e6.99 (m, 1H), 6.87 (s, 1H), 4.22e4.18 (m,
3
d
52.5, 50.5, 39.0, 36.7, 33.2; HRMS (EI-TOF) Calcd for C22
H
22BrNO
4
þ
7
1
2
(M) 443.0732, found 443.0736.
H), 3.74 (s, 3H), 3.72 (s, 3H), 3.66 (s, 3H), 3.41e3.37 (m, 1H),
.85e2.77 (m, 1H), 2.64e2.57 (m, 1H). C{ H} NMR (100 MHz,
): 170.0, 169.9, 143.6, 137.3, 128.6, 128.1, 127.2, 126.6, 126.2,
13
1
4.3.22. Dimethyl 2-(2-(5-bromo-1-methyl-1H-indol-3-yl)-2-
phenylethyl)malonate (3v). The compound was synthesized by
CDCl
3
d
Please cite this article in press as: Talukdar, R.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.12.001

R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
11
reacting dimethyl 2-phenylcyclopropane-1,1-dicarboxylate 1a
50 mg, 0.189 mmol) and 5-bromo-1-methyl-1H-indole 2d (50 L,
(24 mg,
.038 mmol) in overall 3.0 mL dry DCE following the mentioned
HRMS (ESI-TOF) Calcd for C19
365.1609.
H
25
O
7
(MþH)þ 365.1600, found
(
0
0
m
.378 mmol) in presence of catalytic amount of Yb(OTf)
3
4.5.2. Dimethyl 5-(1-methyl-1H-indol-3-yl)cyclohex-3-ene-1,1-
optimized reaction condition. Purified with 18% ethyl acetate in
dicarboxylate (7). The compound was synthesized using the pre-
ꢀ
hexane solvent. Yellowish solid (86 mg, yield 91%). Mp 124e126 C.
viously mentioned procedure. Thick colorless liquid (33 mg, yield
ꢁ
1
ꢁ1
R
f
0.45 (35% EtOAc/hexanes). IR (Neat, cm ) 2952, 2925, 2854,
87%). R
f
0.38 (20% EtOAc/hexanes). IR (Neat, cm ) 3027, 2952,
1
750,1733,1601,1544,1477,1435,1376,1339,1274,1224,1152,1072,
2926, 2854, 1734, 1615, 1550, 1470, 1448, 1433, 1374, 1328, 1296,
1248, 1194, 1175, 1130, 1082, 1057, 1014, 946, 845, 741. H NMR
1
1
1
041, 864, 793, 768, 748, 706. H NMR (400 MHz, CDCl
J¼1.4 Hz, 1H), 7.31e7.17 (m, 5H), 7.11 (d, J¼8.7 Hz, 1H), 6.88 (s, 1H),
.14e4.10 (m, 1H), 3.73 (s, 3H), 3.71 (s, 3H), 3.67 (s, 3H), 3.37e3.33
3
):
d
7.53 (d,
(400 MHz, CDCl
7.11e7.07 (m, 1H), 6.83 (s, 1H), 5.88e5.79 (m, 2H), 3.80 (s, 3H), 3.73
(s, 3H), 3.58 (s, 3H), 2.85e2.81 (m, 1H), 2.75e2.70 (m, 1H),
3
):
d
7.61 (d, J¼7.8 Hz, 1H), 7.29e7.19 (m, 2H),
4
13
1
(
(
1
3
m, 1H), 2.77e2.70 (m, 1H), 2.62e2.55 (m, 1H). C{ H} NMR
100 MHz, CDCl ): 169.9, 168.8, 143.1, 136.0, 128.9, 128.7, 127.9,
27.3, 126.8, 124.7, 122.0, 117.0, 112.5, 110.8, 52.7, 52.6, 50.1, 40.4,
1
3
1
3
d
2.60e2.54 (m, 1H), 2.17 (dd, J¼13.3, 10.5 Hz, 1H). C{ H} NMR
(100 MHz, CDCl ): 172.4, 171.7, 137.3, 130.4, 126.9, 125.8, 124.0,
3
d
þ
5.1, 33.0; HRMS (EI-TOF) Calcd for C22
H
22BrNO
4
(M) 443.0732,
121.7, 119.3, 118.8, 117.4, 109.4, 53.6, 52.8, 52.6, 35.3, 32.7, 30.9, 30.6;
found 443.0735.
HRMS (EI-TOF) Calcd for C19
28.1543.
H22NO
4
(MþH)þ 328.1540, found
3
4
.4. General procedure for the synthesis of dimethyl (E)-2-
allyl-2-(4-phenyl-2-arylbut-3-en-1-yl)malonate 4 and 6
4.6. General procedure for the synthesis of 2-(2,2-diaryl)
ethyl)malonic acids from dialkyl (2-(2,2-diaryl)ethyl)malo-
nates 8 and 9
To a suspension of NaH (1.5 mmol) in dry THF (1.0 mL) a solu-
tion of dimethyl (E)-2-(4-phenyl-2-arylbut-3-en-1-yl)malonate 3p
or 3t (1.0 mmol) in the same solvent (2.0 mL) was added at room
To a solution of dialkyl (2-(2,2-diaryl)ethyl)malonates 3a or 3s
(1.0 mmol) in methanol (3.0 mL), a 2(N) aq solution of NaOH
(0.2 mL) was added at room temperature and the reaction mixture
was kept under vigorous stirring for 2 h. Then the reaction mixture
was neutralized with 10% aq HCL solution and the aqueous layer
was extracted with ethyl acetate (5ꢂ2.0 mL). The combined organic
extract was washed with brine, dried over anhydrous sodium sul-
fate and the solvent was removed under reduced pressure. The
crude concentrate was purified by flash column chromatography
on silica gel (230e400 mesh) using ethyl acetate in petroleum ether
(50%) as the eluent to afford the pure products 8 or 9 as colorless
thick liquids.
2
temperature under N atmosphere and stirred for 5 min. Then allyl
bromide (1.5 mmol) was added dropwise and the reaction mixture
ꢀ
was heated to 65 C under stirring for 30 min. After complete
consumption of the starting material (monitored by TLC) the re-
action was quenched with water (2.0 mL). After separating the
organic layer, the aqueous layer was extracted with dichloro-
methane (4ꢂ2.0 mL). The combined organic extract was washed
with brine, dried over anhydrous sodium sulfate and the solvent
was removed under reduced pressure. The crude concentrate was
purified by flash column chromatography on silica gel
(
230e400 mesh) using ethyl acetate in petroleum ether (8%) as
the eluent to afford the pure product 4 and 6 as colorless thick
liquid.
4.6.1. 2-(2-Phenyl-2-(2,4,6-trimethoxyphenyl)ethyl)malonic
8). The compound was synthesized by reacting dimethyl 2-(2-
phenyl-2-(2,4,6-trimethoxyphenyl)ethyl)malonate 3a (50 mg,
0.125 mmol) in 500 L MeOH solvent with 50 L 2(N) aq NaOH
acid
(
0
0
0
4
.5. General procedure for the synthesis of dimethyl 2 ,4 ,6 -
m
m
0
trimethoxy-1,4-dihydro-[1,1 -biphenyl]-3,3(2H)-dicarboxylate
solution following the known reaction condition. Purified with 50%
5
or dimethyl 5-(1-methyl-1H-indol-3-yl)cyclohex-3-ene-1,1-
ethyl acetate in hexane solvent. Thick colorless liquid (44 mg, yield
ꢁ1
dicarboxylate 7
95%). R
606, 1494, 1454, 1418, 1326, 1224, 1205, 1149, 1119, 1061, 1039, 985,
f
0.40 (75% EtOAc/hexanes). IR (Neat, cm ) 2935, 2841, 1713,
1
1
To a solution of Grubbs’ IInd generation catalyst (0.1 mmol) in
dry DCM (0.5 mL), a solution of dimethyl (E)-2-allyl-2-(4-phenyl-2-
arylbut-3-en-1-yl)malonate 4 or 6 in the same solvent (1.0 mL) was
3
949, 813, 783, 747. H NMR (400 MHz, CDCl ): d 7.28e7.25 (m, 2H),
7.22e7.18 (m, 2H), 7.11e7.08 (m, 1H), 6.07 (s, 2H), 4.70 (dd, J¼11.4,
5.04 Hz, 1H), 3.76e3.74 (m, 3H), 3.70e3.62 (m, 6H), 3.30e3.26 (m,
13
1
added at room temperature under N
2
atmosphere and the reaction
1H), 3.00e2.93 (m, 1H), 2.76e2.67 (m, 1H). C{ H} NMR (125 MHz,
CDCl ): 175.4, 175.1, 160.3, 159.5, 144.2, 127.8, 127.7, 125.5, 110.8,
mixture was stirred at room temperature for 6 h. After complete
consumption of the starting material (monitored by TLC) the sol-
vent was removed under reduced pressure. The crude concentrate
was purified by flash column chromatography on silica gel
3
d
91.2, 55.6, 55.3, 50.5, 36.9, 31.0; HRMS (ESI-TOF) Calcd for
C
20
H22NaO
7
(MþNa)þ 397.1263, found 397.1263.
(
230e400 mesh) using ethyl acetate in petroleum ether (8%) as the
4.6.2. 2-(2-(4-Methoxyphenyl)-2-(1-methyl-1H-indol-3-yl)ethyl)
malonic acid (9). The compound was synthesized by reacting di-
methyl 2-(2-(4-methoxyphenyl)-2-(1-methyl-1H-indol-3-yl)ethyl)
eluent to afford the pure product 5 or 7 as colorless thick liquid.
4
.5.1. Dimethyl 5-(2,4,6-trimethoxyphenyl)cyclohex-3-ene-1,1-
malonate 3s (50 mg, 0.126 mmol) in 500
50 L 2(N) aq NaOH solution following the known reaction condi-
tion. Purified with 50% ethyl acetate in hexane solvent. Thick col-
orless liquid (41 mg, yield 89%). R 0.45 (75% EtOAc/hexanes). IR
mL MeOH solvent with
dicarboxylate (5). The compound was synthesized using the
previously mentioned procedure. Thick colorless liquid (33 mg,
yield 81%). R
2
m
ꢁ
1
f
0.37 (20% EtOAc/hexanes). IR (Neat, cm ) 2952,
f
ꢁ1
839, 1735, 1606, 1591, 1495, 1454, 1435, 1332, 1300, 1249, 1223,
(Neat, cm ) 2928, 2856, 1722, 1611, 1547, 1511, 1466, 1423, 1375,
1
1
1
(
(
204, 1174, 1152, 1121, 1079, 1061, 1044, 949, 845, 813. H NMR
400 MHz, CDCl ): 6.10 (s, 2H), 5.63e5.57 (m, 1H), 5.54e5.50
m, 1H), 4.02e3.95 (m, 1H), 3.78 (s, 6H), 3.73 (s, 6H), 3.62 (s, 3H),
1327, 1248, 1178, 1074, 1034, 929, 832, 742. H NMR (400 MHz,
3
d
CDCl
3
):
d
7.42 (d, J¼8.0 Hz, 1H), 7.22e7.13 (m, 4H), 6.99 (t, J¼7.3 Hz,
1H), 6.86e6.79 (m, 3H), 4.24e4.18 (m, 1H), 3.75e3.70 (m, 6H),
13
13
1
2
.82e2.76 (m, 1H), 2.47e2.40 (m, 1H), 2.30e2.26 (m, 2H).
C
3.45e3.42 (m, 1H), 2.86e2.80 (m, 1H), 2.61e2.53 (m, 1H). C{ H}
NMR (100 MHz, CDCl ): 174.7, 158.3, 137.4, 135.3, 129.0, 127.1,
126.1, 121.8, 119.7, 119.0, 117.3, 114.1, 109.3, 55.3, 50.0, 39.9, 35.0,
1
{
H} NMR (125 MHz, CDCl
3
):
d
172.8, 171.8, 159.8, 159.4, 131.6,
3
d
120.7, 112.6, 91.2, 55.9, 55.3, 54.4, 52.7, 52.5, 32.3, 30.2, 29.2;
Please cite this article in press as: Talukdar, R.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.12.001

12
R. Talukdar et al. / Tetrahedron xxx (2015) 1e12
3
3
2.8; HRMS (ESI-TOF) Calcd for C21
66.1345.
H20NO
5
(MꢁH)ꢁ 366.1341, found
3. For ring opening reactions of DA-cyclopropanes: (a) Gladow, D.; Reissig, H.-U. J.
Org. Chem. 2014, 79, 4492; (b) Wales, S. M.; Walker, M. M.; Johnson, J. S. Org.
Lett. 2013, 15, 2558; (c) Beyzavi, M. H.; Lentz, D.; Reissig, H.-U.; Wiehe, A. Eur. J.
Org. Chem. 2013, 269; (d) Gladow, D.; Reissig, H.-U. Helv. Chim. Acta 2012, 95,
1818; (e) Moran, J.; Smith, A. G.; Carris, R. M.; Johnson, J. S.; Krische, M. J. J. Am.
Chem. Soc. 2011, 133, 18618; (f) Harrington, P.; Kerr, M. A. Tetrahedron Lett. 1997,
Acknowledgements
3
8, 5949; (g) Emmett, M. R.; Kerr, M. A. Org. Lett. 2011, 13, 4180; (h) Dulin, C. C.;
MKG thanks IIT-Kanpur and DST, India, for financial support for
conducting this research. RT thanks CSIR, India, AS thanks IIT
Kanpur, India, and DPT thanks UGC, India for fellowships.
Murphy, K. L.; Nolin, K. A. Tetrahedron Lett. 2014, 55, 5280; (i) Nanteuil, F. D.;
Loup, J.; Waser, J. Org. Lett. 2013, 15, 3738; (j) Piccialli, V.; Graziano, M. L.; Iesce,
M. R.; Cermola, F. Tetrahedron Lett. 2002, 43, 8067; (k) Emmett, M. R.; Grover, H.
K.; Kerr, M. A. J. Org. Chem. 2012, 77, 6634; (l) Lifchits, O.; Charette, A. B. Org.
Lett. 2008, 10, 2809; (m) Garve, L. K. B.; Barkawitz, P.; Jones, P. G.; Werz, D. B.
Org. Lett. 2014, 16, 5804.
. (a) Ivanova, O. A.; Budynina, E. M.; Grishin, Y. K.; Trushkov, I. V.; Verteletskii, P.
V. Eur. J. Org. Chem. 2008, 5329; (b) Chagarovskiy, A. O.; Budynina, E. M.; Iva-
nova, O. A.; Grishin, Y. K.; Trushkov, I. V.; Verteletskii, P. V. Tetrahedron 2009, 65,
5385.
Supplementary data
4
1
Supplementary data ( H NMR and 13C NMR spectra for all the
new compounds and HPLC chromatograms of 3a and 3r.) associated
with this article can be found in the online version, at http://
dx.doi.org/10.1016/j.tet.2015.12.001.
5
. (a) Ghorai, M. K.; Talukdar, R.; Tiwari, D. P. Chem. Commun. 2013, 8205; (b)
Ghorai, M. K.; Talukdar, R.; Tiwari, D. P. Org. Lett. 2014, 16, 2204; (c) Talukdar, R.;
Tiwari, D. P.; Saha, A.; Ghorai, M. K. Org. Lett. 2014, 16, 3954.
6
. (a) Singh, I. P.; Bharate, S. B. Nat. Prod. Rep. 2006, 23, 558; (b) Kitao, J.; Kitamura,
N.; Kumo, N.; Arimitsu, K.; Iwasaki, H.; Ozeki, M.; Kurume, A.; Yamashita, M.
Heterocycles 2011, 83, 143; (c) Morimoto, S.; Nonaka, G. I.; Nishioka, I.; Ezaki, N.;
Takizawa, N. Chem. Pharm. Bull. 1985, 33, 2281; (d) Na, M.; Jang, J.; Min, B. S.;
Lee, S. J.; Lee, M. S.; Kim, B. Y.; Oh, W. K.; Ahn, J. S. Bioorg. Med. Chem. Lett. 2006,
References and notes
1. For some representative reviews on DA-cyclopropane chemistry see: (a) De
Simone, F.; Waser, J. Synthesis 2009, 20, 3353; (b) Reissig, H.-U.; Zimmer, R.
Chem. Rev. 2003, 103, 1151; (c) Cavitt, M. A.; Phun, L. H.; France, S. Chem. Soc. Rev.
1
6, 4738.
7
. Portet, B.; Fabre, N.; Roumy, V.; Gornitzka, H.; Bourdy, G.; Chevalley, S.; Sauvain,
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Please cite this article in press as: Talukdar, R.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.12.001