Iodine-promoted synthesis of 3-arylindolizine-1-carboxylates from 2-(2-nitro-1-arylethyl)malonates and pyridine

Article abstract of DOI:10.3184/174751913X13737205567934

An efficient and straightforward one-pot synthetic protocol has been developed for the synthesis of 3-arylindolizine- 1-carboxylates via 1,3-dipolar annulation of 2-(2-nitro-1-arylethyl)malonates with pyridine and subsequent aromatisation in the presence of molecular iodine. The structure of methyl 3-(4-methoxyphenyl)indolizine-1-carboxylate (2a) and methyl 3-iodo-2-(4- nitrophenyl)indolizine-1-carboxylate (2f) was further confirmed by X-ray single crystal analysis. Website

Full text of DOI:10.3184/174751913X13737205567934

526 RESEARCH PAPER
SEPTEMBER, 526–530
JOURNAL OF CHEMICAL RESEARCH 2013
Iodine-promoted synthesis of 3-arylindolizine-1-carboxylates from
2-(2-nitro-1-arylethyl)malonates and pyridine
Yun Li, Zhengquan Zhou, Weijian Ye, Juanjuan Liu, Juan Yao and Cunde Wang*
School of Chemistry and Chemical Engineering, Yangzhou University, 180 Siwangting Street, Yangzhou 225002, P. R. China
An efficient and straightforward one-pot synthetic protocol has been developed for the synthesis of 3-arylindolizine-
1-carboxylates via 1,3-dipolar annulation of 2-(2-nitro-1-arylethyl)malonates with pyridine and subsequent aromati-
sation in the presence of molecular iodine. The structure of methyl 3-(4-methoxyphenyl)indolizine-1-carboxylate
(2a) and methyl 3-iodo-2-(4-nitrophenyl)indolizine-1-carboxylate (2f) was further confirmed by X-ray single crystal
analysis.
Keywords: indolizine; 3-arylindolizine-1-carboxylate; molecular iodine; 1,3-dipolar annulation; aromatisation
The indolizine ring is a key structural unit for many natural
products, synthetic pharmaceuticals, and a wide variety of bio-
logically active compounds.1–3 Indolizine derivatives with the
π-conjugated heteroaryl–(hetero)aryl motifs as the fluorescent
core objects have been frequently used in molecular materi-
als.4–7 The novel polysubstituted indolizine derivatives have
been a rich source of candidates with potential pharmaceutical
and fluorescent applications that have encouraged the design
and synthesis of new analogues with increased pharmacologi-
cal activity and photonic luminescence. Thus, to meet the need
of modern drug discovery and molecular materials, the syn-
thetic methodology of polysubstituted indolizines is developed
continually to address the many challenges associated with
the design of new pharmaceutical agents and photoelectric
material. Although, there are several methods for the prepara-
tion of the polysubstituted indolizine derivatives, most current
procedures involve multistep.8–14 The development of efficient
methods for the synthesis of polysubstituted indolizine
derivatives requires attention.
In one of our electroluminescent materials and medicinal
chemistry programmes, we needed 3-arylindolizine-1-car-
boxylates to prepare more complex analogues containing
indolizine core. During the past decade, the development of
synthetic routes to 3-arylindolizine-1-carboxylates has been
the focus of intense research. As a key intermediate, 3-arylin-
dolizine-1-carboxylates were frequently synthesised by multi-
step and metal-catalysed direct functionalisation of indolizines
using an indolizine as a starting material. For example, Xia and
co-worker reported that 3-haloindolizines were synthesised
firstly via Cu(II) halide mediated halogenation of indolizines,
following the Suzuki–Miyaura reaction of 3-haloindolizines
and phenylboronic acid provided 3-arylindolizines.15,16 After-
wards Liu and co-workers developed the direct Suzuki–Miy-
aura-type coupling of indolizines without 3-halo substitutent
with arylboronic acids to synthesis of 3-arylated indolizines.17
Subsequently, You and co-workers described a palladium–
copper bimetallic catalytic system with the assistance of Cu2Cl2
and BQ to yield the arylation of indolizine with arylboronic
acids in one step.18 Gevorgyan and co-workers also reported
the palladium-catalysed direct arylation of indolizines with
aryl bromides. In this reaction, the C–H bond of indolizines
directly coupled with aryl bromides to selectively give the C-3
arylated indolizines.19 Recently, Zhao20 investigated the C-3
arylation of indolizines with aryltrifluoroborate salts in the
presence of a Pd(OAc)2/AgOAc/ KOAc catalytic system to
yield 3-arylated indolizines derivatives. Our continued interest
in expanding the scope and potential application of the 3-
arylated indolizines derivatives prompted us to explore the
feasibility of construction of a 3-arylindolizine-1-carboxylate
skeleton by using 2-(2-nitro-1-arylethyl)malonates as a 1,3-
dipolar addition species under appropriate conditions. Thus,
we designed and synthesised some 3-arylindolizine-1-carbox-
ylates. As a result of this study, we achieved a facile, efficient
and concise synthesis of 3-arylindolizine-1-carboxylates via
1,3-dipolar annulation of 2-(2-nitro-1-arylethyl)malonates
with pyridine and subsequent aromatisation in the presence of
molecular iodine. Here we report our preliminary results and
a proposed mechanism for the process.
Results and discussion
The substrates, 2-(2-nitro-1-arylethyl)malonates, were pre-
pared in excellent yields by the Knoevenagel condensation
of dimethyl malonate with various substituted benzaldehydes,
following the Michael addition with nitromethane under basic
conditions according to the reported procedure.21,22 Then,
methyl 3-(4-methoxyphenyl)indolizine-1-carboxylate (2a)
was chosen as the model product to test the direct 1,3-dipolar
annulation process of 2-(2-nitro-4-methoxyphenylethyl) malo-
nate with pyridine in the presence of molecular iodine at room
temperature, however, no reaction occurred as indicated by
TLC result (Scheme 1). A complex mixture was formed when
the reaction temperature was increased to 80 °C, the isolated
yield in 38% (entry 2, Table 1) was achieved after work-up
and purification by column chromatography. The product
was characterised as methyl 3-(4-methoxyphenyl)indolizine-
1-carboxylate (2a) on the basis of its spectral and analytical
data. The stereochemistry of 2a was obtained from a single
crystal X-ray analysis. ORTEP diagrams of 2a is shown in
Fig. 1. To our delight, reaction of 2-(2-nitro-4-methoxyphenyl-
ethyl) malonate 1a with 2.0 equiv. of iodine in pyridine at
120 °C gave methyl 3-(4-methoxyphenyl) indolizine-1-car-
boxylate (2a) in 65% yield (entry 3, Table 1). Higher reaction
temperature, for example 140 °C, could make the reaction time
shorter, but meanwhile results in a slightly lower yield (entry
4, Table 1). Encouraged by these results, the reaction condi-
tions were then screened with the aim of optimising the yield
of 2a. Increasing the amount of iodine to 2.4 equiv., the yield
in 65% of 2a was obtained (entry 5, Table 1). In view of this,
further increase of the amount of iodine had no significant
effect on the reaction. But decreasing the amount of iodine
to 1.5 equiv., the reaction rate was decelerated along with low
yield (entry 6, Table 1). Moreover, expanding reaction time
had also no significant effect on the reaction (entry 7, Table 1).
The reaction of 2a and pyridine could proceed in other reaction
media, such as DMSO and DMF (entries 8–9, Table 1). Among
these tested solvents (entries 3, 8 and 9, Table 1), pyridine was
demonstrated to be the best. A series of experiments revealed
that the optimal results were obtained when the reaction of
1a with pyridine was performed in the presence of iodine
(2.0 equiv.) at 120 °C for 48 h, whereby the yield of 2a reached
65% (entry 3, Table 1).Thus, having established the optimal
* Correspondent. E-mail: wangcd@yzu.edu.cn

JOURNAL OF CHEMICAL RESEARCH 2013 527
Scheme 1 I2-promoted synthesis of indolizine-1-carboxylate 2a.
Table 1 Optimisation of temperature, time and solvents in the
synthesis of 2a
Entry 1a(mol)/I2(mol)/Pyridine/T(°C)/t(h)/Solventa
Yield/%b
1
2
3
4
5
6
7
8
9
1/2/Pyridine/rt/48/ Pyridine
0
38
65
48
65
42
64
42
18
1/2/Pyridine/80/48/ Pyridine
1/2/Pyridine/120/48/ Pyridine
1/2/Pyridine/140/36/ Pyridine
1/2.4/Pyridine/120/48/ Pyridine
1/1.5/Pyridine/120/48/ Pyridine
1/2/Pyridine/120/56/ Pyridine
1/2/Pyridine(1mL)/120/48/ DMSO
1/2/Pyridine(1mL)/120/48/ DMF
a 1a/I2 (mol/mol). b Isolated yield.
Fig. 2 Molecular structure of 3-iodoindolizine-1-carboxylate
2f, non-hydrogen atoms are shown at the 30% probability
level.
conditions for the 2a synthesis, a series of reactions of sub-
strates 1b–f with pyridine were carried out under the identical
conditions as for 2a in Table 1, entry 3. It was found that the
2-(2-nitro-1-arylethyl)malonates 1 bearing a methoxy, methyl,
chloro or bromo at the 4-position of aryl substituents were tol-
erated under the above conditions to afford the corresponding
3-arylindolizine-1-carboxylates (2a-2e) in moderate yields
(Scheme 2). However, under identical conditions as that for
2a, the reaction of 2-[2-nitro-1-(4-nitrophenyl)ethyl]malonate
(1f) with pyridine in the presence of iodine (2.0 equiv.) at 120
°C for 48 h gave the different indolizine-1-carboxylate (2f) in
62% (entry 6, Table 2). The structure of 2f was further con-
firmed by X-ray single crystal analysis and its spectral and
analytical data (Fig. 2). Crystallographic data of 2a and 2f
were listed in Table 3. Crystallographic data for 2a and 2f have
been deposited with the Cambridge Crystallographic Data
Centre with the deposition number CCDC 809149 and 921514.
These data can be obtained free of charge on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax (+44)
1223 336033, E-mail: deposit@ccdc.cam.ac.uk].23
On the basis of the above experimental results together with
X-ray single crystal analysis, a plausible mechanism for the
synthesis of indolizine-1-carboxylate (2a–f) is proposed as
depicted in Scheme 3–5. The transformation starts from an
intermolecular annulation reaction of 2-(2-nitro-1-arylethyl)
malonates 1 in pyridine in the presence of iodine generating
a key intermediate A. Intermediate methyl 2-(4-methoxyphe-
nyl)-3-nitrocyclopropanecarboxylate was isolated once before
the reaction was completed, its structure was further confirmed
by its spectral and analytical data (Scheme 3).
Subsequently, when the substituent of aromatic ring is
methoxy, methyl, chloro or bromo, selectively nucleophilic
addition of pyridine to intermediate A gives rise to pyridinium
compound, which then undergoes intramolecular nucleophilic
annulation reaction to furnish a tetrahydroindolizine. Finally,
the denitration and aromatisation of tetrahydroindolizine yield
the product 2a–e (Scheme 4).
Additionally, a possible mechanism for the formation of
the indolizine-1-carboxylate 2f is depicted in Scheme 5.
Because of the electron-withdrawing of nitro aromatic ring,
selectively nucleophilic addition of pyridine to α-carbon of
nitrocyclopropane intermediate A gives rise to a pyridinium
compound, following intramolecular annulation reaction to
gives a 3-nitrotetrahydroindolizine. Under the base conditions,
3-nitrotetrahydroindolizine undergoes keto−enol tautomerism
between nitro and α-carbon-hydrogen to form the intermediate
enol. Then the enol intermediate reacts with iodine to furnish a
electrophilic product 3-iodo-3-nitrotetrahydroindolizine. The
final aromatisation achieves via the denitration reaction by the
utilization of nitro as the leaving group to keep 3-postion iodo
substitutent in indolizine-1-carboxylate 2f (Scheme 5).
Fig. 1 Molecular structure of indolizine-1-carboxylate 2a,
non-hydrogen atoms are shown at the 30% probability level.

528 JOURNAL OF CHEMICAL RESEARCH 2013
Scheme 2 Iodine-promoted synthesis of indolizine-1-carboxylates.
Table 2 I2-promoted synthesis of indolizine-1-carboxylates
X-ray crystallographic analysis was performed with a Smart-1000
CCD diffractometer using monochromatic Mo KR radiation (λ)
0.71073 Å) and integrated with the SAINT-Plus program. All calcula-
tions were performed with programs from the SHELXTL crystallo-
graphic software package. The elemental analyses were performed
in a Perkin-Elmer 240C instrument. Flash chromatography was
performed on silica gel (230–400 mesh) eluting with ethyl acetate–
hexanes mixture. All reactions were monitored by TLC. All reagents
and solvents were purchased from commercial sources and purified
commonly before used.
Entry
R
X
Y
Yield/%
1
2
3
4
5
6
4-CH3O
H
4-CH3
4-Br
4-Cl
4-NO2
4-CH3OC6H4
C6H5
4-CH3C6H4
4-BrC6H4
4-ClC6H4
I
H
2a 65
2b 51
2c 58
2d 60
2e 55
2f 62
H
H
H
H
4-O2NC6H4
The syntheses of 2-(2-nitro-1-arylethyl)malonates 1 were achieved
starting from commercially available substituted benzaldehydes,
nitromethane and dimethyl malonate using the standard procedure
In summary, a facile and efficient synthesis of 3-arylindoli-
zine-1-carboxylates has been developed via 1,3-dipolar annu-
lation of 2-(2-nitro-1-arylethyl)malonates with pyridine and
subsequent aromatisation in the presence of molecular iodine
for the generation of a wide range of structurally interesting,
pharmacologically and photoelectrically significant compounds.
This protocol, combining construction and modification of
the 3-arylindolizine-1-carboxylate and 2-arylindolizine-1-
carboxylate skeleton, increases the structural diversity of final
products from readily available starting materials. Further
work on the utilisation and extension of the scope of the meth-
odology is currently under investigation in our laboratory.
Synthesis of indolizine-1-carboxylates (2a–f); general procedure
The appropriate 2-(2-nitro-1-arylethyl)malonates (2 mmol) and iodine
(1.02 mg, 4 mmol) were dissolved in 5 mL of pyridine at room
temperature, and the resultant mixture was stirred under 120 °C for
48 h, the completion of reaction was confirmed by TLC (EtOAc/
hexanes, 1:10). Subsequently, the mixture was cooled to room
temperature, excessive pyridine was removed by decreased pressure.
The residues were added with water (10 mL), then the resultant was
extracted with dichloromethane (2 x 10 mL), the organic phase was
washed with 10% sodium thiosulfate, water and brine, dried over
anhydrous sodium sulfate. After removal of dichloromethane, the
residues were purified by flash chromatography (silica gel, EtOAc/
hexanes, 1/20) to give product 2a–f.
Experimental
Methyl 3-(4-methoxyphenyl)indolizine-1-carboxylate (2a): Yellow
1
All melting points were determined in aYanaco melting point appara-
tus and are uncorrected. IR spectra were recorded in a Nicolet FT-IR
5DX spectrometer. The 1H NMR (600 MHz) and 13C NMR (150 MHz)
spectra were recorded in a Bruker AV-600 spectrometer with TMS as
internal reference in CDCl3 solutions. J values are given in Hz. Only
discrete or characteristic signals for the 1H NMR are reported. The MS
spectra were obtained on a ZAB-HS mass spectrometer with 70 eV.
solid, m.p. 130–132 °C (CH2Cl2/PE); H NMR (CDCl3, 600 MH)
δ (ppm) 8.15 (dd, J = 9.3, 7.2 Hz, 2H), 7.39 (d, J = 7.8 Hz, 2H), 7.29
(s, 1H), 7.15 (d, J = 9.3 Hz, 1H), 6.98 (d, J = 7.8 Hz, 2H), 6.78–6.61
(m, 1H), 3.81 (s, 3H), 3.64 (s, 3H); 13C NMR (150 MHz, CDCl3)
δ 163.6, 162.9, 138.1, 132.2, 131.1(2C), 130.6, 128.2, 127.5, 121.3,
120.0, 115.6, 113.4(2C), 103.5, 55.5, 52.3; IR (KBr, cm−1): 2993,
2838, 1689, 1636, 1609, 1510, 1492, 1223, 1174, 1106, 950, 838;
Scheme 3 Plausible mechanism for the formation of intermediate A.

JOURNAL OF CHEMICAL RESEARCH 2013 529
Table 3 Crystallographic data for compounds 2a and 2f
Entry
Compound 2a
Compound 2f
Empirical formula
Formula weight
Wavelength/Å
Temperature/K
Crystal system
Space group
C17H15NO3
C16H11IN2O4
422.17
281.30
0.71073
0.71073
296(2)
296(2)
Triclinic,
Triclinic,
P-1
P-1
a = 8.3888(14) Å
b = 8.9604(15) Å
c = 10.6074(18) Å
α = 75.211(2) °
β = 71.373(2) °
γ = 84.738(2) °
730.5(2)
a = 8.2774(12) Å
b = 9.9061(14) Å
c = 10.0956(14) Å
α = 83.048(2) °
β = 79.836(2) °
γ = 81.262(2) °
801.6(2)
Unit cell dimensions
Volume/Å3
Z
2
2
Calculated density/g cm−3
Absorption correction
F(000)
1.279
1.749
None
None
296
412
Crystal size/mm
θ range for data collection
h,k,l ranges
0.28 × 0.26× 0.24
2.09 to 27.40 °
–10<h<10, –11<k<11,
–13<l<12
0.28 ×0.26 ×0.24
2.06 to 27.44 °
–10<h<10, –12<k<12,
–12<l<13
Reflections collected/unique
6392/3253
7005/3575
[R(int) = 0.0228]
97.9%
[R(int) = 0.0294]
97.7%
Completeness
Data/restraints/parameters
3253/0/192
1.072
3575/0/209
1.072
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
R1 = 0.0545, wR2 = 0.1695
R1 = 0.0726, wR2 = 0.1898
0.616 and -0.205
R1 = 0.0345, wR2 = 0.0911
R1 = 0.0413, wR2 = 0.1070
1.105 and –0.685
Largest diff. peak and hole/e Å−3
Scheme 4 Plausible mechanism for the formation of 2a–e.
MS(EI)(m/z): 282.09 [(M+H)+] (78%); HRESIMS calcd for C17H15NO3
(M+H)+ 282.1130; found 282.1043; Anal. Calcd for C17H16NO3: C,
72.58; H, 5.37; N, 4.98. Found: C, 72.77; H, 5.28; N, 5.08%.
Methyl 3-phenylindolizine-1-carboxylate (2b):15 Yellow solid, m.p.
Methyl 3-(4-bromophenyl)indolizine-1-carboxylate (2d): Yellow
solid, m.p. 152–154 °C (CH2Cl2/PE); H NMR (CDCl3, 600 MH)
1
δ (ppm) 9.26 (d, J = 7.2 Hz, 1H), 8.22 (d, J = 6.6 Hz, 1H), 7.51–7.45
(m, 4H), 7.29 (s, 1H), 7.12–7.05 (m, 1H), 6.77 (d, J = 7.2 Hz, 1H),
3.86 (s, 3H); 13C NMR (150 MHz, CDCl3) δ 163.3, 138.4, 138.3,
131.8, 131.3(2C), 130.2(2C), 128.5, 128.2, 126.6, 120.4, 120.0, 116.1,
104.2, 52.3; IR (KBr, cm−1): 2946, 1672, 1554, 1512, 825; MS(EI)
(m/z): 330.20 [(M+1)+] (47%); HRESIMS calcd for C16H12BrNO2
(M+H)+ 330.0130; found 330.0067; Anal. Calcd for C16H13BrNO2: C,
58.20; H, 3.66; N, 4.24. Found: C, 58.32; H, 3.56; N, 4.44%.
1
114–116 °C (CH2Cl2/PE); H NMR (CDCl3, 600 MH) δ (ppm) 8.23
(d, J = 9.3 Hz, 1H), 8.20 (d, J = 7.2 Hz, 1H), 7.54–7.42 (m, 4H),
7.39–7.35 (m, 1H), 7.29 (s, 1H), 7.09–7.06 (m, 1H), 6.70–6.66 (m,
1H), 3.87 (s, 3H); 13C NMR (150 MHz, CDCl3) δ 163.6, 139.8, 138.5,
132.0, 131.9, 128.9(2C), 128.8, 128.7, 128.3(2C), 128.2, 121.0, 120.2,
116.1, 52.4; IR (KBr, cm−1): 2954, 1690, 1607, 1519, 1498, 1081, 855,
758; MS(EI)(m/z): 251.02 [M+] (51%); HRESIMS calcd for C16H14NO2
(M+H)+ 252.1025; found 252.0954; Anal. Calcd for C16H13NO2: C,
76.48; H, 5.21; N, 5.57. Found: C, 76.52; H, 5.20; N, 5.68%.
Methyl 3-(4-chlorophenyl)indolizine-1-carboxylate (2e): Yellow
1
solid, m.p. 139–141 °C (CH2Cl2/PE); H NMR (CDCl3, 600 MH)
δ (ppm) 8.27 (d, J = 12 Hz, 1H), 8.23 (d, J = 6.6 Hz, 1H), 7.52–7.47
(m, 4H), 7.27 (s, 1H), 7.10–7.07 (m, 1H), 6.74 (d, J = 7.2 Hz, 1H),
3.91 (s, 3H); 13C NMR (150 MHz, CDCl3) δ 163.0, 149.3, 138.4,
132.6, 131.8, 129.5(2C), 129.3, 129.2, 123.2(2C), 120.4, 119.0, 116.1,
104.2, 52.5; IR (KBr, cm−1): 2946, 2858, 1730, 1652, 1550, 1510,
820; MS(EI)(m/z): 286.20 [(M+1)+] (38%); HRESIMS calcd for
C16H12ClNO2 (M+H)+ 286.0635; found 286.0544; Anal. Calcd for
C16H13ClNO2: C, 67.26; H, 4.23; N, 4.90. Found: C, 67.37; H, 4.09; N,
4.96%.
Methyl 3-(4-methylphenyl)indolizine-1-carboxylate (2c):23 Yellow
solid, m.p. 140–142 °C (CH2Cl2/PE); 1H NMR (DMSO-d6, 600 MH)
δ (ppm) 8.26–8.24 (m, 2H), 7.42 (d, J = 7.8 Hz, 2H), 7.30 (d, J =
7.8 Hz, 2H), 7.22 (s, 1H), 7.07 (t, J = 6.0 Hz, 1H), 6.69 (t, J = 7.2 Hz,
1H), 3.91 (s, 3H), 2.42 (s, 3H); 13C NMR (150 MHz, CDCl3) δ 163.5,
142.6, 138.1, 136.9, 131.1, 128.9(2C), 128.8(2C), 128.4, 127.7, 121.1,
119.9, 115.7, 103.7, 52.2, 21.6; IR (KBr, cm−1): 2945, 2855, 1691,
1547, 1510, 1446, 1365, 1218, 1046, 820, 772, 742, 564; MS(EI)
(m/z): 266.32 [(M+1)+] (70%); HRESIMS calcd for C17H15NO2
(M+H)+ 266.1181; found 266.1099; Anal. Calcd for C17H16NO2: C,
76.96; H, 5.70; N, 5.28. Found: C, 76.88; H, 5.89; N, 5.32%.
Methyl 3-iodo-2-(4-nitrophenyl)indolizine-1-carboxylate (2f):
Yellow solid, m.p. 142–143 °C (CH2Cl2/PE); 1H NMR (CDCl3,
600 MH) δ (ppm) 8.24 (d, J = 8.4 Hz, 2H), 8.19–8.17 (m, 2H), 7.48

530 JOURNAL OF CHEMICAL RESEARCH 2013
Scheme 5 Plausible mechanism for the formation of 2f.
3
4
5
6
7
8
9
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6642.
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7742.
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(d, J = 8.4 Hz, 2H), 7.14–7.11 (m, 1H), 6.89–6.86 (m, 1H), 3.64 (s,
3H); 13C NMR (151 MHz, CDCl3) δ 163.0, 150.4, 146.3, 141.4,
130.6(2C), 130.3, 130.2, 129.7, 124.6(2C), 122.9, 120.0, 117.6, 107.8,
50.4; IR (KBr, cm−1): 3088, 2982, 2938, 1720, 1679, 1595, 1508,
1099, 1042, 858; MS(EI)(m/z): 423.08 [(M+1)+] (49%); HRESIMS
calcd for C16H11IN2O4 (M+H)+ 422.9840; found 422.9750;Anal. Calcd
for C16H12IN2O4: C, 45.52; H, 2.63; N, 6.64. Found: C, 45.38; H, 2.72;
N, 6.88%.
Methyl
2-(4-methoxyphenyl)-3-nitrocyclopropanecarboxylate:
White solid, m.p. 87–89 °C (AcOEt/PE); 1H NMR (CDCl3, 600 MH)
δ (ppm) 7.16 (d, J = 7.2 Hz, 2H), 6.88 (d, J = 7.2 Hz, 2H), 4.73 (dd,
J1 = 6.6 Hz, J2= 8.4Hz, 1H), 4.63 (dd, J1 = 9.0 Hz, J2 = 10.2Hz, 1H),
3.96 (dd, J1 = 7.2 Hz, J2 = 5.4Hz, 1H), 3.80 (s, 3H), 3.65 (s, 3H); 13
C
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7783.
NMR (CDCl3, 150 MHz) δ (ppm) 170.1, 158.2, 129.1(2C), 127.3(2C),
113.4, 78.6, 54.2, 50.9, 38.4, 36.7; IR (KBr, cm−1): 2954, 2837, 1731,
1613, 1552, 1516, 1440, 1384, 1327, 1300, 1257, 1117, 1027, 987,
836, 622.
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J. Heterocyclic Chem., 2007, 44, 783.
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Financial support of this research by the National Natural
Science Foundation of China (NNSFC 21173181) is gratefully
acknowledged by authors. A Project Funded by the Priority
Academic Program Development of Jiangsu Higher Education
Institutions.
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Received 20 May 2013; accepted 17 June 2013
Paper 1301956 doi: 10.3184/174751913X13737205567934
Published online: 6 September 2013
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