Michael addition reaction of fluorinated nitro compounds

Article abstract of DOI:10.1002/cjoc.201100412

The Michael addition reactions of fluorinated nitro compounds with electron deficient olefins to give γ-fluoro-γ-nitro-esters, nitriles and ketones which bear a fluorinated quaternary carbon center were reported. The reactions were promoted by TMG, afford

Full text of DOI:10.1002/cjoc.201100412

FULL PAPER
DOI: 10.1002/cjoc.201100412
Michael Addition Reaction of Fluorinated Nitro Compounds†
Huan, Fenga(郇凤)
Hu, Huaweib(胡华伟)
Huang, Yangen*,b(黄焰根)
Chen, Qingyuna(陈庆云)
Guo, Yong*,a(郭勇)
a Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of
Sciences, Shanghai 200032, China
b College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
The Michael addition reactions of fluorinated nitro compounds with electron deficient olefins to give
γ-fluoro-γ-nitro-esters, nitriles and ketones which bear a fluorinated quaternary carbon center were reported. The
reactions were promoted by TMG, affording the desired adducts in acceptable to good yields.
Keywords Michael addition reaction, fluorinated nitro compounds, fluorinated quaternary carbon center
Introduction
has aroused much attention and plenty of synthetic
methodologies for fluorinated ketones have been de-
veloped.[17-19] However, research on the construction of
fluorinated nitro quaternary carbon center is still rare.
Generally speaking, there are two common strategies for
the introduction of the fluorine atom: (a) direct fluorina-
tion of organic compounds with kinds of electrophilic or
nucleophilic fluorinating reagents and (b) the use of
easily available simple fluorine-containing building
blocks. We have synthesized fluoronitroalkanes as use-
ful building blocks for Henry reactions.[20] Meanwhile
The Michael addition reaction has become one of the
most popular carbon-carbon bond forming reactions
ever since its discovery. Because of the broad spectrum
of potential donors and acceptors, this reaction is excep-
tionally versatile and a wide range of synthetically use-
ful adducts bearing various functional groups can be
generated.[1] As nucleophilic donors, nitroalkanes have
already drawn enormous attention[2] because of the easy
manipulation of the nitro functionality into amines (re-
duction), hydrides (radical denitration), aldehydes, ke-
tones (Nef reaction), and other valuable building
blocks.[3]
It is well-known that, due to the unique nature of the
fluorine, the introduction of fluorine into an organic
molecule can profoundly change the properties of the
molecule in many aspects, including lipophilicity,
bioavailability and metabolic stability.[4-14] Especially,
the organofluorine derivatives always have different
bioactivity compared with the non-fluorine containing
compounds. As a result, organofluorine compounds
have found their application in pharmaceuticals. Ac-
cording to incomplete statistics, 20% of pharmaceuticals
and 30%—40% of agrochemicals on market and 30% of
the leading 30 blockbuster drugs on sale contain at least
one fluorine atom.[15,16]
O
O
F
OH
OH
S
O
Me
HO
Me
O
Me
HO
Me
Me
F
F
O
O
F
Fludrocortisone
Advair Diskus
O
F
Cl
OMe
F
OH
OH
N
HO
Et
HO
O
O
O
O
N
F3C
OMe
H
O
O
More specifically, many medicines or biologically
active compounds contain a fluorinated quaternary car-
bon center, such as Fludrocortisone, Advair Diskus (3.6
×109 $ US sales in 2008, top 4), BMS-204352 and
Flurithromycin (Figure 1).[14] Recently, incorporation of
a fluorine atom to α-position of carbonyl compounds
OH
O
BMS-204352
Flurithromycin
Figure 1 Examples of medicines and biologically active com-
pounds containing a fluorinated quaternary carbon center.
*
E-mail: yguo@sioc.ac.cn (Y. Guo); Tel.: 0086-021-54925462; Fax: 0086-021-64166128; hyg@dhu.edu.cn (Y. Huang); Tel.: 0086-021-67792612;
Fax: 0086-021-6779260
Received September 28, 2011; accepted November 29, 2011; published online March 7, 2012.
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cjoc.201100412 or from the author.
† Dedicated to Professor Weiyuan Huang on the occasion of his 90th birthday.
798
© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2012, 30, 798—802

Michael Addition Reaction of Fluorinated Nitro Compounds
we envisioned fluoronitroalkane could also be a good
donor in Michael addition reaction. Herein we wish to
report our recent research of the Michael addition reac-
tion of fluoronitroalkanes to give fluorine-containing
quaternary carbon center adducts.
Afterwards, all of the five nitro compounds 1a—1e
obtained previously were used to react with methyl
acrylate in the presence of TMG in DCM (Table 2, En-
tries 1―5). It was found that 1-fluoro-1-nitrohexane (1a)
was the most active and gave the corresponding Michael
adduct in 85% isolated yield (Table 2, Entry 1). Low
yields (46%) of Michael addition products were ob-
tained when nitro compounds 1d and 1e were used (Ta-
ble 2, Entries 4, 5). The reactions with acrylonitrile gave
similar results. Linear chain aliphatic 1-fluoro-1-nitro-
hexane (1a) gave a better yield (72%) than others
(45%—62%) (Table 2, Entries 6—10).
Two selected fluorinated nitro compounds (1a and
1c) were used to react with methyl vinyl ketone (MVK),
to give the Michael adducts smoothly (Table 2, Entries
11, 12). In order to study the steric effect of the Michael
acceptor, we also performed the reaction of 1c with
(E)-4-phenylbut-3-en-2-one. The reaction showed to be
ineffective which can hardly get the adduct, indicating
that it is quite sensitive to the substituent group on the β
position of the electron deficient olefin.
The synthesis of 4-fluoro-4-nitro-5-phenylpentane-
nitrile (3g) was previously reported by Takeuchi and co-
workers.[21] In their study, the fluorinated nitro sub-
stance [fluoro(nitro)methyl]benzene was obtained by
electrophilic fluorination reaction and sequent decar-
boxylation of ethyl α-nitro carboxylic ester. 4-Fluoro-4-
nitro-5-phenylpentanenitrile (3g) was obtained by Mi-
chael addition reaction in a similar way (Scheme 1). We
found that the fluorinated nitro compounds can be syn-
thesized from the nitro compounds with only one elec-
tron withdrawn group, thus avoiding tedious decar-
boxylation steps.
Results and Discussion
We prepared five fluorinated nitro compounds 1a—
1e which we have used in Henry reaction.[20] In order to
screen the appropriate base for the Michael addition
reaction, the reaction of 1-fluoro-1-nitrohexane (1a) and
methyl acrylate (2a) was chosen as the model reaction.
Among the three bases screened, N,N,N',N'-tetra-
methylguanidine (TMG) was found to be the most ef-
fective catalyst while Et3N failed to promote the reac-
tion, and in the reaction with 1,5-diazabicyclo[4.3.0]-
non-5-ene (DBU) several fluorated compounds were
detected by 19F NMR along with the desired adduct
(Table 1, Entries 1—3). We then studied the effect of
the solvent (Table 1, Entries 4—7). Dipolar solvents,
such as dichloromethane (DCM) and acetonitrile, turned
out to give better results than the nonpolar solvent such
as p-xylene. Decreasing the load of the base led to sharp
decrease of the yield (Table 1, Entries 8, 9). The influ-
ence of the concentration of the reactant was also stud-
ied (Table 1, Entries 10, 11). Best results were given in
0.4 mol/L, while an increase or decrease in concentra-
tion both led to apparently drop in yield.
Table 1 Optimization of reaction conditionsa
F
base
r.t.
+
CO2Me
NO2
F
2a
1a
Scheme 1 The procedure designed by Takeuchi
NO2
CO2Me
CO2Me
KF, FClO3
NaBH4/ EtOH
-20 oC, 2 h, 70%
CO2Me
NO2
Ph
Ph
3a
THF, 22 oC, 1 h
F
NO2
Entry
1
Base
Et3N
Solvent
Time/h
40
Yieldb/%
CN
Ph
F
CN
Ethyl acetate
Ethyl acetate
Ethyl acetate
DCM
NR
15
71
89
68
65
85
30
53
52
59
Ph
F
NO2
NO2
43%
2
DBU
TMG
TMG
TMG
TMG
TMG
TMG
TMG
TMG
TMG
40
3
40
4
24
Conclusions
5
THF
24
In summary, a series of novel α-fluoronitroalkanes
were prepared and applied to the Michael addition reac-
tion with methyl acrylate, acrylonitrile and MVK. The
Michael adducts with a fluorine-containing quaternary
center were obtained in acceptable to good yields. This
method provides a practical method for the preparation
of biologically useful fluorinated derivatives.
6
p-Xylene
Acetonitrile
DCM
24
7
24
8c
9d
10e
11f
24
DCM
24
DCM
24
DCM
24
a
Unless otherwise noted, reactions were performed with 0.2
mmol of 1a, 0.2 mmol of 2a, and 0.1 mmol of base in 0.5 mL
Experimental
solvent. b Yield based on 19F NMR. c 0.02 mmol TMG. d 0.04
e
f
General information for the Michael addition reac-
tion
mmol TMG. 0.2 mL DCM. 1 mL DCM. DCM＝dichloro-
methane, THF＝tetrahydrofuran, DBU＝1,5-diazabicyclo[4.3.0]-
non-5-ene, TMG＝N,N,N',N'-tetramethylguanidine.
All reagents were used as received from commercial
Chin. J. Chem. 2012, 30, 798—802
© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Huan et al.
FULL PAPER
Table 2 Michael addition of fluorinated nitro compoundsa
TMGb
R1
NO2
F
NO2
+
R2
R1
DCM, r.t.
R2
F
Entry
1
Fluorinated nitro compound
Electron deficient olefin
Product
Time/h Yieldc/%
CO2Me
NO2
4
4
19
22
23
23
23
20
26
24
24
27
85
81
70
46
46
72
61
62
48
45
F
NO2
F
1a
3a
NO2
CO2Me
Ph
Ph
2
3
F
NO2
F
3b
1b
Ph
NO2
Ph
F NO2
3c
CO2Me
CO2Me
2a
F
1c
CO2Me
O
NO2
O
F
NO2
4
O
O
F
1d
3d
CO2Me
NO2
F
NO2
5
F
1e
3e
CN
CN
NO2
4
4
6
F
NO2
F
1a
3f
NO2
Ph
Ph
F
NO2
7
F
3g
1b
Ph
NO2
Ph
CN
CN
F
NO2
8
F
2b
1c
3h
CN
CN
O
NO2
O
F
NO2
9
O
O
F
1d
3i
NO2
F
NO2
10
F
1e
3j
O
NO2
4
4
11
12
24
70
F
F
NO2
3k
1a
O
O
2c
Ph
NO2
Ph
24
49
F
F
NO2
1c
3i
a Conditions: fluorinated nitro compounds (1.0 equiv.), electron deficient olefin (1.0 equiv.) and TMG (0.5 equiv.) stirred at room tem-
perature in DCM. b TMG＝N,N,N',N'-tetramethylguanidine. c Isolated yield.
800
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Chin. J. Chem. 2012, 30, 798—802

Michael Addition Reaction of Fluorinated Nitro Compounds
sources, unless specified otherwise, or prepared as de-
scribed in the literature. 1H NMR spectra were recorded
on a Bruker AM 300 (300 MHz) spectrometer with
TMS as an internal standard (negative for upfield). 19F
NMR spectra were recorded on a Bruker AM 300 (282
MHz) with CFCl3 as an external standard (negative for
upfield). 13C NMR spectra were recorded on a Bruker
AV-400 (100 MHz) spectrometer with CDCl3 as an in-
ternal standard (negative for upfield). MS and HRMS
were recorded on a Hewlett-Packard HP-5989A spec-
trometer and a Finnigan MAT-8483 mass spectrometer.
Infrared spectra were measured with a Perkin-Elmer
983 spectrometer. Column chromatography was per-
formed using silica gel (mesh 300—400). All solvents
were purified by standard methods.
21.0 Hz), 27.5 (d, J＝3.3 Hz); IR (neat) ν: 3002, 2955,
－
1
1747, 1570, 1453, 1353, 1201, 1075, 694 cm ; HRMS
(ESI) calcd for C11H12FNO4 [M ＋ Na] ＋ 264.0643,
found 264.0646.
Methyl 5-(1,3-dioxolan-2-yl)-4-fluoro-4-nitropen-
1
tanoate (3d): yellow solid; m.p. 45—47 ℃; H NMR
(CDCl3, 300 MHz) δ: 5.10 (t, J＝5.1 Hz, 1H), 3.97—
3.85 (m, 4H), 3.70 (s, 3H), 2.58—2.51 (m, 5H), 2.30—
2.28 (m, 1H); 19F NMR (CDCl3, 282 MHz) δ: －128.8
(m); 13C NMR (CDCl3, 100 MHz) δ: 171.6, 118.6 (d,
J＝238.0 Hz), 99.0 (d, J＝4.9 Hz), 65.0 (d, J＝6.6 Hz),
52.1, 41.0 (d, J＝19.8 Hz), 32.4 (d, J＝21.0 Hz), 26.9 (d,
J＝4.2 Hz); IR (KBr) ν: 2958, 2903, 1731, 1573, 1441,
－
1
1339, 1213, 1144, 986 cm ; HRMS (ESI) calcd for
C9H14FNO6 [M＋Na]＋ 274.0697, found 274.0698.
Methyl 4-fluoro-4-nitrohept-6-enoate (3e): colorless
oil; 1H NMR (CDCl3, 300 MHz) δ: 5.78—5.64 (m, 1H),
5.29 (d, J＝5.4 Hz, 1H), 5.25 (d, J＝12.9 Hz, 1H), 3.70
(s, 3H), 3.03—2.79 (m, 2H), 2.73—2.45 (m, 3H),
2.36—2.23 (m, 1H); 19F NMR (CDCl3, 282 MHz) δ:
－130.0 (m); 13C NMR (CDCl3, 100 MHz) δ: 171.6,
127.4 (d, J＝3.7 Hz), 122.5, 120.5 (d, J＝241.0 Hz),
52.1, 41.4 (d, J＝21.5 Hz), 31.5 (d, J＝21.5 Hz), 26.9 (d,
General procedure and spectra data
To a solution of methyl acrylate (0.45 g, 3.0 mmol)
in DCM (6 mL) were added α-fluoronitro compounds
(3.0 mmol) and TMG (0.173 g, 1.5 mmol). The reaction
mixture was stirred at room temperature for the time as
given in Table 1 and then the solvent was removed un-
der vacuum. 1 mol•L－ hydrochloric acid (3 mL) was
1
added to neutralize the base. The mixture was extracted
with CH2Cl2 (3 mL×3). The combined organic phases
were dried over anhydrous Na2SO4, filtered and evapo-
rated under vacuum. The residue was purified by flash
column chromatography on silica gel (hexane/EtOAc,
V∶V＝97∶3) to yield the desired addition product.
Methyl 4-fluoro-4-nitrononanoate (3a): colorless oil;
1H NMR (CDCl3, 300 MHz) δ: 3.70 (s, 3H), 2.50—2.27
(m, 6H), 1.32—1.27 (m, 6H), 0.90 (t, J＝6.9 Hz, 3H);
19F NMR (CDCl3, 282 MHz) δ: －129.8 (m); 13C NMR
(CDCl3, 100 MHz) δ: 171.6, 121.4 (d, J＝240.0 Hz),
51.9, 36.9 (d, J＝21.9 Hz), 32.0 (d, J＝21.9 Hz), 30.9,
27.0 (d, J＝2.9 Hz), 22.1, 21.7 (d, J＝3.3 Hz), 13.7; IR
(neat) ν: 2958, 2874, 1744, 1566, 1439, 1320, 1204, 841
J＝4.1 Hz); IR (neat) ν: 3088, 2957, 1743, 1567, 1440,
－
1204, 940, 841 cm 1; HRMS (ESI) calcd for
C8H12FNO4 [M＋Na]＋ 228.0643, found 228.0645.
1
4-Fluoro-4-nitrononanenitrile (3f): colorless oil; H
NMR (CDCl3, 300 MHz) δ: 2.74—2.08 (m, 6H), 1.50—
1.58 (m, 1H), 1.33—1.25 (m, 5H), 0.89 (t, J＝6.9 Hz,
3H); 19F NMR (CDCl3, 282 MHz) δ: －130.0 (m); 13C
NMR (CDCl3, 100 MHz) δ: 120.2 (d, J＝241.0 Hz),
117.2, 36.8 (d, J＝21.0 Hz), 32.6 (d, J＝22.3 Hz), 30.8,
22.1, 21.7 (d, J＝2.9 Hz), 13.7, 11.2 (d, J＝15.3 Hz); IR
(neat) ν: 2960, 2873, 2254, 1568, 1440, 1356, 1139, 840
－
＋
1
cm ; HRMS (ESI) calcd for C9H15FN2O2 [M＋Na]
225.1010, found 225.1011.
4-Fluoro-4-nitro-5-phenylpentanenitrile (3g): yellow
oil; 1H NMR (CDCl3, 300 MHz) δ: 7.37—7.34 (m, 3H),
7.23—7.17 (m, 2H), 3.53—3.36 (m, 2H), 2.80—2.66
(m, 1H), 2.51—2.28 (m, 3H); 19F NMR (CDCl3, 282
MHz) δ: －129.7 (m).
－
＋
1
cm ; HRMS (ESI) calcd for C10H18FNO4 [M＋Na]
258.1112, found 258.1113.
Methyl 4-fluoro-4-nitro-5-phenylpentanoate (3b):
1
white solid; m.p. 56—58 ℃; H NMR (CDCl3, 300
MHz) δ: 7.35—7.30 (m, 3H), 7.22—7.17 (m, 2H), 3.68
(s, 3H), 3.53—3.38 (m, 2H), 2.80—2.40 (m, 3H),
2.39—2.20 (m, 1H); 19F NMR (CDCl3, 282 MHz) δ:
－128.8 (m); 13C NMR (CDCl3, 100 MHz) δ: 171.6,
130.9, 130.2, 128.8, 128.3, 120.7 (d, J＝243.0 Hz), 52.1,
43.2 (d, J＝21.0 Hz), 31.6 (d, J＝21.0 Hz), 27.0 (d, J＝
4.1 Hz); IR (KBr) ν: 2955, 1732, 1564, 1440, 1206
4-Fluoro-4-nitro-4-phenylbutanenitrile (3h): colo-
rless oil; 1H NMR (CDCl3, 300 MHz) δ: 7.64 (d, J＝7.8
Hz, 2H), 7.52—7.47 (m, 3H), 3.22—2.89 (m, 2H),
2.58—2.38 (m, 2H); 19F NMR (CDCl3, 282 MHz) δ:
－130.7 (dd, J＝21.7, 19.7 Hz); 13C NMR (CDCl3, 100
MHz) δ: 131.6 (d, J＝23.0 Hz), 131.7 (d, J＝1.3 Hz),
129.3 (d, J＝1.6 Hz), 125.0 (d, J＝9.1 Hz), 118.0 (d,
J＝240.0 Hz), 117.2, 33.1 (d, J＝21.5 Hz), 11.7(d, J＝
4.6 Hz); IR ν: 3067, 2970, 2907, 2254, 1573, 1498,
1453, 1159, 762.651 cm－ 1; HRMS (ESI) calcd for
C10H9FN2O2 [M＋Na]＋ 231.0540, found 231.0541.
5-(1,3-Dioxolan-2-yl)-4-fluoro-4-nitropentanenitrile
－
＋
1
cm ; HRMS (ESI) calcd for C12H14FNO4 [M＋Na]
278.0799, found 278.0799.
Methyl 4-fluoro-4-nitro-4-phenylbutanoate (3c):
colorless oil; 1H NMR (CDCl3, 300 MHz) δ: 7.68—7.65
(m, 2H), 7.49—7.47 (m, 3H), 3.70 (s, 3H), 3.18—2.87
(m, 2H), 2.56—2.35 (m, 2H); 19F NMR (CDCl3, 282
MHz) δ: －128.6 (dd, J＝23.7, 18.3 Hz); 13C NMR
(CDCl3, 100 MHz) δ: 171.6, 132.8 (d, J＝23.0 Hz),
131.1 (d, J＝1.2 Hz), 129.0 (d, J＝1.6 Hz), 125.2 (d,
J＝8.7 Hz), 119.1 (d, J＝239.0 Hz), 52.1, 32.4 (d, J＝
1
(3i): colorless oil; H NMR (CDCl3, 300 MHz) δ: 5.10
(q, J＝4.5 Hz, 1H), 4.03—3.85 (m, 4H), 2.77—2.50 (m,
5H), 2.41—2.31 (m, 1H); 19F NMR (CDCl3, 282 MHz)
δ: －127.7 (m); 13C NMR (CDCl3, 100 MHz) δ: 116.6
(d, J＝253.3 Hz), 116.2, 97.8 (d, J＝5.3 Hz), 64.1, 64.0,
Chin. J. Chem. 2012, 30, 798—802
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801

Huan et al.
FULL PAPER
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39.6 (d, J＝19.8 Hz), 31.7 (d, J＝21.9 Hz), 10.1 (d, J＝
5.8 Hz); IR (neat) ν: 2970, 2254, 1738, 1566, 1365,
－
1217, 843, 528 cm 1; HRMS (ESI) calcd for
C8H11FNO4 [M＋Na]＋ 241.0595, found 241.0596.
4-Fluoro-4-nitrohept-6-enenitrile (3j): colorless oil;
1H NMR (CDCl3, 300 MHz) δ: 5.74—5.63 (m, 1H),
5.34 (d, J＝9.9 Hz, 1H), 5.29 (d, J＝17.1 Hz, 1H),
3.00—2.88 (m, 2H), 2.77—2.47 (m, 3H), 2.45—2.33
(m, 1H); 19F NMR (CDCl3, 282 MHz) δ: －129.5 (m);
13C NMR (CDCl3, 100 MHz) δ: 126.4 (d, J＝11.0 Hz),
123.3, 119.3 (d, J＝246.0 Hz), 117.1, 41.2 (d, J＝21.0
Hz), 31.0 (d, J＝21.4 Hz), 11.1 (d, J＝5.8 Hz); IR (neat)
ν: 3088, 2987, 2926, 2254, 1644, 1574, 1439, 1358,
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－
1177, 940, 837 cm 1; HRMS (ESI) calcd for
C7H9FN2O2 [M＋Na]＋ 195.0540, found 195.0543.
1
5-Fluoro-5-nitrodecan-2-one (3k): colorless oil; H
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NMR (CDCl3, 300 MHz) δ: 2.69—2.59 (m, 1H), 2.55—
2.22 (m, 5H), 2.16 (s, 3H), 2.12—1.95 (m, 1H), 1.58—
1.42 (m, 1H), 1.13—1.38 (m, 5H), 0.88 (t, J＝6.6 Hz,
3H); 19F NMR (CDCl3, 282 MHz) δ: －129.1 (m); 13C
NMR (CDCl3, 100 MHz) δ: 205.1 (d, J＝1.3 Hz), 121.7
(d, J＝240.2 Hz), 37.0 (d, J＝21.9 Hz), 35.8 (d, J＝2.9
Hz), 30.8, 30.6 (d, J＝21.9 Hz), 29.7, 22.1, 21.7 (d, J＝
2.9 Hz), 13.6; IR (neat) ν: 2960, 2935, 2873, 1723, 1564,
－
1
1468, 1435, 1360, 1170, 843 cm ; HRMS (ESI) calcd
for C10H18FNO3 [M＋Na]＋ 242.1163, found 242.1159.
4-Fluoro-4-nitro-4-phenylbutan-2-one (3l): yellow
oil; 1H NMR (CDCl3, 300 MHz) δ: 7.67—7.64 (m, 2H),
7.48—7.45 (m, 3H), 3.11—2.80 (m, 2H), 2.69—2.46
(m, 2H), 2.17 (s, 3H); 19F NMR (CDCl3, 282 MHz) δ:
－127.5 (dd, J＝25.7, 17.5 Hz); 13C NMR (CDCl3, 100
MHz) δ: 205.1, 133.1 (d, J＝23.1 Hz), 131.1 (d, J＝1.2
Hz), 128.9 (d, J＝1.2 Hz), 125.2 (d, J＝8.7 Hz), 119.5
(d, J＝238.5 Hz), 36.4 (d, J＝2.0 Hz), 31.0 (d, J＝21.1
Hz), 29.9; IR (neat) ν: 2948, 2911, 1722, 1567, 1452,
－
1
1357, 1168, 1001, 715 cm ; HRMS (ESI) calcd for
C11H12FNO3 [M＋Na]＋ 248.0693, found 248.0691.
Acknowledgments
This project was supported by the National Natural
Science Foundation of China (No. 21172241) and the
Science and Technology Commission of Shanghai Mu-
nicipality (No. 11ZR1445700).
References
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www.cjc.wiley-vch.de
© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2012, 30, 798—802