Substituent chemical shifts of N-arylsuccinanilic acids, N-arylsuccinimides, N-arylmaleanilic acids, and N-arylmaleimides

Article abstract of DOI:10.1002/mrc.2450

NMR spectra of a series of N-arylsuccinanilic acids, N-arylsuccinimides, N-arylmaleanilic acids, and N-arylmaleimides were examined to estimate the electronic effect of the amide and imide groups on the chemical shifts of the hydrogen and carbon nuclei of the benzene ring.

Full text of DOI:10.1002/mrc.2450

Research Article
Received: 20 February 2009
Revised: 14 April 2009
Accepted: 16 April 2009
Published online in Wiley Interscience: 26 May 2009
(www.interscience.com) DOI 10.1002/mrc.2450
Substituent chemical shifts of
N-arylsuccinanilic acids, N-arylsuccinimides,
N-arylmaleanilic acids, and N-arylmaleimides
Hye Sun Lee, Ji Sook Yu and Chang Kiu Lee∗
NMR spectra of a series of N-arylsuccinanilic acids, N-arylsuccinimides, N-arylmaleanilic acids, and N-arylmaleimides were
examined to estimate the electronic effect of the amide and imide groups on the chemical shifts of the hydrogen and carbon
c
nuclei of the benzene ring. Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Keywords: 1H NMR; 13C NMR; succinanilic acids; succinimides; maleanilic acids; maleimides
Introduction
spectra of 1–4 were obtained with a 0.1 M solution in DMSO-d6.
Unambiguous assignments for the signals were made by 1H–1H
COSYand1H–13CHETCORspectroscopy. Thechemicalshiftvalues
for 1H and 13C signals are listed in Tables 2–9.
Maleimides are commonly used in organic synthesis especially
as dienophiles in Diels–Alder reactions[1] and as a compo-
nent in Michael-type addition reactions.[2] For example, the
Michael reaction of enaminones with N-(p-tolyl)maleimide gave
succinimide-containing enaminones which showed interesting
crystallographic phenomena.[3] Once either type of addition takes
place, the result is a derivative of succinimide, which is a 1,4-
dicarbonyl compound. The dicarbonyl system is, in turn, a useful
building block in the synthesis of various alicyclic and heterocyclic
skeletons. N-(m- or p-substituted) maleimides have been used for
in situ carbazole syntheses because the products have potential
antiviral activities.[4]
Z
H
N
O
NH2
O
β
ether
+
O
OH
α
Z
O
O
1
O
Z
Ac2O
In the course of the synthesis of a series of N-phenyl derivatives
of succinimides (2) and maleimides (4) from succinic anhydride
and maleic anhydride, respectively, we observed some remarkable
characteristics of the NMR chemical shifts in both series as
well as for the intermediates, N-phenylsuccinanilic acids (1) and
N-phenylmaleanilic acids (3). Here we report our NMR studies on
these four series.
N
O
2
Z
H
N
O
NH2
O
β
ether
+
O
OH
α
Z
O
O
Results and Discussions
3
Syntheses of N-arylsuccinimides and N-arylmaleimides are widely
reported in literature. Heating succinic or maleic anhydride with
substituted anilines is one of the typical methods.[5] Decar-
boxylative oxidation of N-aryl-γ -lactam-2-carboxylic acids with
(NH4)2Ce(NO3)6 [CAN] – NaBrO3 in refluxing acetonitrile–water
is one of the most novel methods for the synthesis of
N-arylsuccinimides.[6] The succinanilic acids 1 were prepared by
reacting succinic anhydride with m- and p-substituted anilines in
diethyl ether at room temperature.[7] The crude products could
be converted without purification to N-phenylsuccinimides; some
material was purified by recrystallization from various solvents in
order to obtain analytically pure compounds for the NMR studies.
A uniform concentration of 0.1 M is essential for the correlation
study. The maleimides 4 were prepared similarly from maleic an-
hydride and m- and p-substituted anilines.[8] The maleanilic acid
intermediates were also purified by recrystallization. The NMR
O
Z
Ac2O
N
O
4
Z: a, m-NO2; b, m-Br; c, m-Cl; d, m-F; e, m-OCH3; f, m-CH3,
g, p-NO2; h, p-Br; i, p-Cl; j, p-F; k, p-OCH3; l, p-CH3, m, H
∗
Correspondence to: Chang Kiu Lee, Department of Chemistry, Kangwon Na-
tionalUniversity,Chuncheon200-701,Korea.E-mail: cklee410@kangwon.ac.kr
Department of Chemistry, Kangwon National University, Chuncheon 200-701,
Korea
c
Magn. Reson. Chem. 2009, 47, 711–715
Copyright ꢀ 2009 John Wiley & Sons, Ltd.

H. S. Lee, J. S. Yu and C. K. Lee
Table 2. 1H NMR chemical shift values (δ) of 0.1 M succinanilic acids
(1) in DMSO-d6
Table 1. Calculated parameters for the chemical shift values of the
protons and carbons in the benzene ring
o-H m-H p-H
i-C o-C m-C p-C
OH
NH
Hα
Hβ 2-H 3-H 4-H 5-H 6-H CH3
0.32 0.02 −0.25 11.3 −9.1 0.7 −5.1
a
b
c
12.21 10.47 2.54 2.61 8.63
12.15 10.13 2.52 2.56 7.95
12.14 10.14 2.52 2.56 7.81
12.45 10.17 2.52 2.57 7.33
12.13 9.93 2.51 2.55 7.30
12.12 9.86 2.51 2.55 7.43
–
–
–
–
–
–
7.88 7.359 7.88
7.20 7.25 7.46
7.07 7.31 7.42
6.84 7.28 7.58
–
–
–
–
O
O
O
O
N
H
H
O
d
e
f
6.60 7.18 7.09 3.71
6.84 7.16 7.35 2.26
0.36 0.05 −0.17 10.3 −8.5 0.8 −4.1
N
H
O
O
g
h
i
12.19 10.59 2.54 2.63 7.82 8.20
12.15 10.09 2.51 2.55 7.55 7.46
12.14 10.09 2.51 2.55 7.60 7.33
12.13 10.00 2.51 2.54 7.59 7.12
12.12 9.79 2.51 2.51 7.48 6.86
12.12 9.85 2.51 2.54 7.46 7.08
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
H
O
N
–
0.00 0.23 0.14 4.1 −1.5 0.2 −0.5
0.06 0.23 0.13 3.6 −1.1 1.0 −0.2
0.38 −0.02 −0.26 9.7 −8.1 0.2 −4.4
j
–
O
O
k
l
3.71
2.24
m
12.12 9.94 2.52 2.55 7.57 7.28 7.01
N
O
δ = 29.14 ppm shows a correlation with the one at δ = 2.56 ppm
which corresponds to β-CH2. Based on both the HMBC and HMQC
spectra it was possible to assign the signals at δ = 2.52 and
2.56 ppm to the α-CH2 and the β-CH2, respectively. Consequently,
the assignments of 13C signals at δ = 29.14 and 31.55 ppm to the
α-CH2 and the β-CH2 were also confirmed.
N
H
H3C
a
(CH3)3N+
–
0.72 0.40 0.34 19.5 −7.3 2.5
2.4
a
a From Refs [11,12].
Similarly, the HMBC spectroscopy for 3c has confirmed the
correlation of NH with β-CH, leading to the assignments of the
signals at δ = 130.20 and 132.15 ppm to the α-CH and β-CH,
1
Althoughtheassignmentswerestraightforwardusing theCOSY
and the HETCOR spectroscopy, those of the two methylenic
carbons and hydrogens of 1 needed HMBC spectroscopy. The
latter experiment is especially informative for confirming the
relationship of the proton and carbon atoms that are separated by
two or three bonds. The HMBC spectrum of 1c clearly shows the
correlations of the signal at δ = 10.14 ppm, which corresponds
to the proton on the N atom of the secondary amide group,
with the 1-C (δ = 141.19 ppm), the 2-C (δ = 118.83 ppm), and
the 6-C (δ = 117.71 ppm) of the phenyl ring. The proton signal
also correlates with the signals at δ = 171.02 and 31.55 ppm,
which correspond to NHC O and β-CH2, respectively. The
respectively. An AB pattern at δ = 6.32 and 6.47 ppm in the H
NMR spectrum of 3c has also been assigned to the α-CH and β-CH,
respectively.
Fluorophenyl derivatives (d and j in each series) were
prepared to acquire accurate assignments of the chemical shifts
by examining the 1H–19F and 13C–19F coupling constants.[9]
At first, we assigned the approximate substituent corrections
for the succinimidyl group from the spectra of the m- and
p-fluoro derivatives, 2d and 2j, and the unsubstituted compound
2m. With the estimated values and the substituent chemical
shift values listed in the literature,[10] it was possible to assign
all signals of 2. After the complete assignments were made,
other methylenic carbon signal at δ = 29.14 ppm does not more accurate substituent chemical shift corrections for the
show a correlation with the N–H signal. Instead, the signal at succinimidyl groups were calculated by averaging the values
Table 3. 13C NMR chemical shift values (δ) of 0.1 M succinanilic acids (1) in DMSO-d6
COOH
CONH
Cα
Cβ
1-C
2-C
3-C
4-C
5-C
6-C
CH3
a
b
c
174.29
174.27
174.25
174.27
174.34
174.35
174.21
174.29
174.32
174.33
174.40
174.38
174.35
171.49
171.02
171.02
171.01
170.63
170.50
171.73
170.79
170.77
170.48
170.02
170.30
170.56
29.14
29.14
29.14
29.14
29.23
29.30
29.03
29.19
29.20
29.28
29.39
29.32
29.28
31.63
31.55
31.55
31.56
31.56
31.52
31.77
31.55
31.52
31.42
31.37
31.46
31.52
140.85
141.16
141.19
141.50
140.99
139.73
145.91
139.15
138.74
136.21
133.02
137.32
139.80
113.43
121.69
118.83
106.14
105.15
119.94
119.02
121.28
120.91
121.08
120.91
119.40
119.37
148.46
122.05
133.53
162.65
159.99
138.30
125.52
131.99
129.09
115.72
114.30
129.53
129.17
117.99
126.03
123.11
109.84
108.87
124.11
142.44
114.90
126.93
158.27
155.47
132.24
123.40
130.66
125.31
–
131.22
118.10
–
130.88
117.71
–
d
e
f
130.80
115.07
–
55.42
21.71
–
129.96
111.66
129.00
116.59
g
h
i
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
j
–
k
l
55.64
20.92
–
m
c
www.interscience.wiley.com/journal/mrc
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2009, 47, 711–715

Substituent chemical shifts of N-arylsuccinimides and N-Arylmaleimides
Table 4. 1H NMR chemical shift values (δ) of 0.1 M
N-phenylsuccinimides (2) in DMSO-d6
Table 6. 1H NMR chemical shift values (δ) of 0.1 M maleanilic acids (3)
in DMSO-d6
CH2
2-H
3-H
4-H
5-H
6-H
CH3
OH
NH
Hα
Hβ
2-H 3-H 4-H 5-H 6-H CH3
a
b
c
2.81
2.76
2.78
2.78
2.77
2.77
2.82
2.77
2.77
2.77
2.75
2.76
2.78
8.22
7.51
7.39
7.15
6.99
7.06
7.61
7.24
7.31
7.32
7.16
7.13
7.26
–
–
7.77
7.61
7.49
7.28
6.83
7.22
–
7.81
7.45
7.53
7.54
7.40
7.36
–
8.28
7.29
7.27
7.16
6.84
7.04
–
–
–
a
b
c
12.91 10.77 6.36 6.51 8.66
12.93 10.48 6.32 6.47 7.97
12.93 10.49 6.32 6.47 7.83
–
–
–
–
–
–
7.94 7.62 7.91
7.26 7.29 7.50
7.14 7.35 7.46
6.91 7.32 7.61
–
–
–
–
–
–
d
e
f
–
–
d
e
f
?
10.51 6.32 6.46 7.37
–
3.76
2.33
–
13.06 10.36 6.31 6.45 7.32
13.11 10.33 6.31 6.46 7.48
6.67 7.23 7.15 3.73
6.91 7.20 7.39 2.28
–
g
h
i
8.36
7.69
7.56
7.31
7.02
7.28
7.49
g
h
i
12.91 10.87 6.36 6.54 7.86 8.23
12.93 10.46 6.31 6.46 7.59 7.51
12.98 10.47 6.31 6.47 7.65 7.38
12.87 10.42 6.30 6.46 7.63 7.17
13.43 10.38 6.30 6.46 7.54 6.91
13.24 10.37 6.30 6.46 7.51 7.13
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
j
–
–
–
–
j
–
k
l
–
–
–
3.78
2.34
–
k
l
3.73
2.26
–
–
–
–
m
7.40
–
–
m
13.12 10.39 6.31 6.48 7.62 7.33 7.09
group is not surprising because they are all secondary amides.
Slight disparities between the succinamidyl and maleamidyl
groups may be due to the presence of a double bond in the
maleimidyl group.
for the series. Similarly, we were able to establish the substituent
chemical shift values for maleimidyl, HOC( O)CH2CH2C( O)NH-,
and HOC( O)CH CHC( O)NH- groups. The results are listed in
Table 1.
Succinimide and maleimide have a 1,3-dicarbonyl system.
Resonance structures I and II in which the lone-pair electrons
on the N atom are delocalized on the two oxygen atoms may play
a role to these contrasting effects.
One of the striking observations is that the succinimidyl group
causes almost no noticeable change in the chemical shift of the
ortho-H. Maleimidyl group causes a very small deshielding of
ortho-H (0.06 ppm). These are in good contrast to the acetamidyl
[CH3C( O)NH-] group which causes a deshielding of ortho-H by
0.38 ppm.[11] It is even more surprising that both the succinimidyl
and maleimidyl groups cause deshieldings of meta-H by 0.23 ppm
while the acetamido group causes a shielding (−0.02 ppm). The
signals corresponding to para-H are shifted 0.14 and 0.13 ppm to
higher frequencies by the succinimidyl and maleimidyl groups,
respectively, but move to lower frequency (−0.26 ppm) by the
acetamido group.
-1/2
O H
-1/2
O H
H
O
Z
Z
Z
-
+
+
+
:
N
N
N
O
H
O
O
H
H
-1/2
-1/2
The acetamidyl group is considered electron withdrawing
in the inductive sense but electron donating in the reso-
nance sense; this is reflected by its σI (0.29) and σR (−0.25)
values.[13] The Hammett σm and σp values are 0.29 and
−0.25, respectively. The agreement of the calculated parameters
for succinamidyl [HOC( O)CH2CH2C( O)NH-], and maleamidyl
[HOC( O)CH CHC( O)NH-]groupswiththoseforanacetamidyl
I
II
III
Because the lone-pair electrons on the N atom can be
delocalized throughout the two carbonyl groups, the N atom
may have a positive charge which attracts electrons from the
benzene ring. The −I effect should be most profound at the
ortho-C and ortho-H. However, the carbonyl oxygen atom and
Table 5. 13C NMR chemical shift values (δ) of 0.1 M N-phenylsuccinimides (2) in DMSO-d6
CH2
C
O
1-C
2-C
3-C
4-C
5-C
6-C
CH3
a
b
c
29.06
29.11
28.99
28.96
28.96
28.70
29.09
28.99
28.98
28.96
28.86
28.91
28.96
177.07
177.38
177.14
177.11
177.33
177.20
176.94
177.18
177.23
177.45
177.61
177.49
177.42
134.21
134.81
133.31
134.70
134.33
132.93
138.88
132.49
132.07
129.47
125.78
130.61
133.22
122.40
130.48
127.49
114.78
113.51
127.80
128.38
129.64
129.34
129.79
128.78
127.36
127.60
148.26
121.68
134.58
162.23
159.92
138.49
124.62
132.31
129.36
116.25
114.54
129.75
129.28
123.41
131.66
128.62
115.55
114.21
129.02
146.93
121.54
133.05
161.86
159.26
138.07
128.60
130.80
134.14
–
131.40
126.96
–
130.97
126.41
–
d
e
f
130.92
123.80
–
55.79
21.04
–
130.06
119.85
128.87
124.46
g
h
i
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
j
–
k
l
55.83
21.20
–
m
c
Magn. Reson. Chem. 2009, 47, 711–715
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
www.interscience.wiley.com/journal/mrc

H. S. Lee, J. S. Yu and C. K. Lee
Table 7. 13C NMR chemical shift values (δ) of 0.1 M maleanilic acids (3) in DMSO-d6
COOH
CONH
Cα
Cβ
1-C
2-C
3-C
4-C
5-C
6-C
CH3
a
b
c
167.42
167.40
167.40
167.50
167.47
167.39
167.35
167.38
167.38
167.35
167.15
167.29
167.37
164.42
164.04
164.05
164.09
163.70
163.65
164.61
163.85
163.84
163.68
163.32
163.52
163.73
130.80
131.32
130.02
130.77
131.01
131.08
130.71
130.66
130.67
130.77
131.34
131.21
130.91
132.03
132.14
132.15
132.10
132.19
132.05
132.22
132.16
132.17
132.24
131.92
132.08
132.18
140.37
140.78
140.64
140.92
140.26
138.96
145.44
138.52
137.84
135.48
131.41
136.43
138.77
113.92
122.08
119.33
106.74
105.71
120.52
119.56
121.83
121.20
121.82
121.68
120.06
120.01
148.47
122.19
133.60
162.66
160.01
138.53
125.53
132.13
127.55
115.94
114.47
129.70
129.31
118.68
126.79
123.89
110.75
109.82
125.09
142.94
115.88
128.95
158.84
156.31
133.51
124.36
130.76
125.80
–
–
131.32
118.65
130.62
118.28
d
e
f
131.03
115.74
–
55.51
21.68
–
130.12
112.26
129.15
117.21
g
h
i
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
j
–
k
l
55.70
20.98
–
m
are very small compared to any secondary amide group (−4.1
and −5.1 ppm). Because of the two carbonyl groups bound to the
N atom, a resonance structure like III is not likely to contribute,
and the electronic shielding at the para-C should be diminished
significantly. The imide and the phenyl rings should be coplanar
for the resonance structure III to have a significant contribution.
But it is known that the two rings are not in the same plane.[14]
In conclusion, we report that the succinimidyl and maleimidyl
groups of N-arylsuccinimides and maleimides show very close
effects on the 1H and 13C chemical shifts of the N-aryl groups. The
electronic effects of the imidyl groups are strikingly different from
those of the secondary amide groups.
Table 8. 1H NMR chemical shift values (δ) of 0.1 M
N-phenylmaleimides (4) in DMSO-d6
HC CH
2-H
3-H
4-H
5-H
6-H
CH3
a
b
c
7.26
7.20
7.21
7.21
7.17
7.17
7.25
7.20
7.20
7.18
7.15
7.16
7.17
8.29
7.61
7.47
7.23
6.92
7.14
7.69
7.32
7.38
7.39
7.23
7.19
7.32
–
–
8.25
7.60
7.48
7.27
6.98
7.11
–
7.80
7.46
7.52
7.54
7.39
7.36
–
7.86
7.38
7.35
7.25
6.90
7.21
–
–
–
–
–
d
e
f
–
–
–
3.76
2.34
–
–
g
h
i
8.36
7.70
7.56
7.34
7.02
7.28
7.49
–
–
–
–
–
–
–
–
j
–
–
–
–
Experimental
k
l
–
–
–
3.78
2.34
–
–
–
–
NMR spectra
m
7.39
–
–
NMR spectra were recorded on a Bruker DPX-400 FT NMR
spectrometer in the Central Lab of Kangwon National University
at 400 MHz for 1H and 100 MHz for 13C and were referenced
to tetramethylsilane. The solutions were of 0.10 M in DMSO-
d6. Each solution was prepared in a 1-ml cylindrical volumetric
flask by weighing the compound into the flask and filling with
solvent containing 1% TMS. A portion (0.6 ml) of the solution
was transferred into a 5-mm NMR tube, and the spectrum was
obtainedat20 ◦C.ThechemicalshiftvaluesarelistedinTables 2–9.
1H NMR spectra were recorded with acquisition times of 2 s using
a 30◦ pulse width, over a spectral width of 8223 Hz. 13C NMR
spectra were recorded with the acquisition time of 1 s using
30◦ pulse width and a spectral width of 138 847 Hz. Waltz-16
broad-band heteronuclear proton coupling was applied using a
decoupler field strength of 2588 Hz. DEPT-edited 13C NMR spectra
were recorded using recovery delay times of 2 s with 122 µs
90◦ decoupler pulse widths. COSY spectra were recorded using
spectral widths of 4112 Hz and acquisition times of 125 µs in t2
with 512 t1 increments and one order of zero-filling. Recycle delay
time of 1.5 s were applied between each of 16 transients recorded
per t1 increment. Pseudo-echo weighting was applied in both
time domains prior to Fourier transformation. HETCOR spectra
were obtained with polarization transfer and refocusing delays
the ortho-H atom are considered to be a part of a six-membered
ring. The electronic effect of the carbonyl O atom in the proximity
is shielding, whereas that of a positively charged N atom is
deshielding. The two opposing effects on the ortho-H may offset
each other, and therefore the calculated parameter is close to zero
for ortho-H.
The −I effect of the positively charged N atom should affect the
electronic shielding of meta- and para-H atoms. The effect should
be greater for the meta-H atom, which is closer to the N atom
than the para-H atom. This is similar to the larger effect of the
(CH3)3N+ –group on the chemical shift of the meta-H (+0.40) than
that of the para-H (0.34).[11]
The contribution of the resonance structures I and II seems
to have a profound effect on the 13C chemical shifts. Amino
groups, in general, cause a significant deshielding of the ipso-
carbon (ca 10–24 ppm) and a shielding of the ortho-carbon
(ca 5–16.5 ppm).[12] The observed values for the succinimidyl
and maleimidyl groups (4.1 and 3.6 for ipso-C and −1.5 and
−1.1 ppm for ortho-C, respectively) are significantly smaller than
for a typical amino group. It seems apparent that the offsetting
effects are the reason for such small deviations. It should be
pointed out that the effects on the chemical shift of para-C by the
succinimidyl and maleimidyl groups (−0.5 and −0.2, respectively)
1
optimized for JCH = 145 Hz; 2048 transients were recorded for
each of 512 t1 increments with a recycle delay time of 1.5 s.
c
www.interscience.wiley.com/journal/mrc
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2009, 47, 711–715

Substituent chemical shifts of N-arylsuccinimides and N-Arylmaleimides
Table 9. 13C NMR chemical shift values (δ) of 0.1 M N-phenylmaleimides (4) in DMSO-d6
C
C
C
O
1-C
2-C
3-C
4-C
5-C
6-C
CH3
a
b
c
135.43
135.30
135.32
135.26
135.16
135.14
135.61
135.28
135.27
135.21
135.07
135.11
135.22
169.91
170.07
170.08
170.04
170.35
170.47
169.81
170.12
170.17
170.42
170.69
170.53
170.52
133.20
133.58
133.41
133.57
133.12
131.95
138.03
131.42
130.98
128.32
124.56
129.42
132.10
121.64
129.85
127.03
114.31
113.30
127.78
127.24
129.19
128.90
129.59
128.82
127.18
127.39
148.29
121.63
133.47
162.24
159.93
138.84
124.82
132.38
129.41
116.31
114.63
129.84
129.46
122.76
131.27
128.15
115.03
113.82
128.92
146.31
121.02
132.60
161.64
159.12
137.75
128.33
130.81
133.39
–
131.02
126.32
–
131.01
125.93
–
d
e
f
130.94
123.24
–
55.81
21.31
–
130.10
119.54
129.18
124.46
g
h
i
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
j
–
k
l
55.85
21.17
–
m
Compounds
N. H. Lee, J. J. Condoluci, T. S. Gac, M. M. Pou, P. M. Radford,
J. Heterocycl. Chem. 1993, 30, 81.
[5] C. Glidewell, J. N. Low, J. M. S. Skakle, J. L. Wardell, Acta Crystallogr.
All the derivatives of 1, 2, 3, and 4 are all known compounds, and
they were prepared by procedures reported in the literature.[7,8]
2005, C61, o216.
[6] G. Barman, M. Roy, J. K. Ray, Tetrahedron Lett. 2008, 49, 1405.
[7] (a) R. Kluger, J. C. Hunt, J. Am. Chem. Soc. 1989, 111, 5921; (b)
S. F. Martin, C. Limberakis, Tetrahedron Lett. 1997, 38, 2617; (c)
Z. G. Le, Z. C. Chen, Y. Hu, Q. G. Zheng, Synthesis 2004, 995; (d)
J. B. Lan, G. L. Zhang, X. Q. Yu, J. S. You, L. Chen, M. Yan, R. G. Xie,
Synlett 2004, 1095; (e) B. Pal, P. K. Pradhan, P. Jaisankar, V. S. Gir,
Synthesis 2003, 1549; (f) A. Kar, N. P. Argade, Synthesis 2002, 221.
[8] (a) M. P. Cava, A. A. Deana, K. Muth, M. J. Mitchell, Org. Syn. Col.
1973,5,944;(b)K. Kishikawa,M. Naruse,S. Kohmoto,M. Yamamoto,
Acknowledgement
We thank Dr Gary Kwong of 3M Co. for proofreading the
manuscript.
References
K. Yamaguchi, J. Chem. Soc. Perkin Trans. 1 2001, 462; (c)
J. F. W. Keana, M. D. Ogan, Y. Lu, M. Beer, J. Varkey, J. Am. Chem.
Soc. 1986, 108, 7957; (d) W. W. K. R. Mederski, M. Baumgarth,
M. Germann, D. Kux, T. Weitzel, Tetrahedron Lett. 2003, 44, 2133.
[9] F. A. Bovey, L. Jelinski, P. A. Mirau, Nuclear Magnetic Resonance
Spectroscopy (2nd edn), Academic Press, Inc: New York, 1988,
pp 437.
[10] E. Pretsch, P. Buhlmann, C. Affolter, Structure Determination of
Organic Compounds (3rd edn), Springer: Berlin, 2000, Chapts. 4
and 5.
[11] E. Pretsch, P. Buhlmann, C. Affolter, Structure Determination of
Organic Compounds (3rd edn), Springer: Berlin, 2000, p 182.
[12] E. Pretsch, P. Buhlmann, C. Affolter, Structure Determination of
Organic Compounds (3rd edn), Springer: Berlin, 2000, p 98.
[13] N. S. Isaacs, PhysicalOrganicChemistry (2nd edn), Longman: Harlow,
1995, p 152.
[1] Representativeexamplesreportedin2008:(a)D. Akalay,G. Duerner,
M. W. Goebel, Eur. J. Org. Chem. 2008, 2365; (b) M. Hoshino,
H. Matsuzaki, R. Fujita, Chem. Pharm. Bull. 2008, 56, 480; (c)
K. M. Brummond,D. Chen,T. O. Painter,S. Mao,D. D. Seifried,Synlett
2008, 759; (d) S. M. Al-Mousawi, M. A. EL-Apasery, M. H. Elnagdi,
Heterocycles 2008, 75, 1151; (e) N. H. Metwally, Heterocycles 2008,
75, 319; (f) H. Yu, P. H. Lee, J. Org. Chem. 2008, 73, 5183; (g)
S. S. P. Chou, H. C. Wang, P. W. Chen, C. H. Yang, Tetrahedron 2008,
64, 5291; (h) G. Bojase, A. D. Payne, A. C. Willis, M. S. Sherburn,
Angew. Chem. Int. Ed. 2008, 47, 910.
[2] (a) H. Cavdar, N. Saracoglu, Tetrahedron 2005, 61, 2401; (b) L. Zu,
H. Xie, H. Li, J. Wang, W. Jiang, W. Wang, Adv. Syn. Cat. 2007, 349,
1882; (c) S. Bouzroura, L. Hammal, B. Nedjar-Kolli, F. Balegroune,
M. Hamadene, S. Poulain, Syn. Commun. 2008, 38, 448.
[3] S. Cunha,W. Rodovalho,N. R. Azevedo,M. O. Mendonca,C. Lariucci,
[14] D. P. Curran, S. Geib, N. DeMello, Tetrahedron 1999, 55, 5681.
I. Vencato, J. Braz. Chem. Soc. 2002, 13, 629.
[4] W. E. Noland, M. J. Walhstrom, M. J. Konkel, M. E. Brigham,
A. G. Trowbridge, L. M. C. Konkel, R. P. Gourneau, C. A. Scholten,
c
Magn. Reson. Chem. 2009, 47, 711–715
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
www.interscience.wiley.com/journal/mrc