A mild highly efficient and green protocol for preparation of N-alk-2′-enoyl cyclic imides using basic ionic liquid [bmlm]OH as base and reaction medium

Article abstract of DOI:10.3184/030823408X356305

An efficient and green protocol for the preparation of N-alk-2′-enoyl cyclic imides at room temperature was developed using a basic ionic liquid, 1-methyl-3-butylimidazolium hydroxide, [bmlm]OH, as a base and a reaction medium.

Full text of DOI:10.3184/030823408X356305

JOURNAL OF CHEMICAL RESEARCH 2008
OCTOBER, 559–561
RESEARCH PAPER 559
A mild highly efficient and green protocol for preparation of N-alk-2'-enoyl
cyclic imides using basic ionic liquid [bmIm]OH as base and reaction medium
Yongjiang Wanga*, Jianwei Maoa and Wen Peib*
aSchool of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Key Laboratory of Agricultural
Products Chemical and Biological Processing Technology of Zhejiang Province, Hangzhou 310023, P. R. China
bCollege of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014, P. R. China
An efficient and green protocol for the preparation of N-alk-2'-enoyl cyclic imides at room temperature was developed
using a basic ionic liquid, 1-methyl-3-butylimidazolium hydroxide, [bmIm]OH, as a base and a reaction medium.
Keywords: N-alk-2'-enoyl cyclic imides, 1-methyl-3-butylimidazolium hydroxide
N-Alk-2'-enoyl cyclic imides are of considerable interest, they
have found increasing applications as important intermediates
in organic synthesis.1-5 However, reports concerning the
synthesis of these compounds are rare, the main route to the
a,b-unsaturated carboxylic acid derivatives involve reactions
of activated carbonyl compound such as an acid chloride with
cyclic imides using BuLi as a base under the temperature
of –78°C in THF.1-2 In the past, we have delineated the
utility of pyridine as base and medium in the reaction and
N-alk-2'-enoyl cyclic imides has been prepared at room
temperature,4 but it suffered from major shortcomings such
as environmentally hazardous residues, low yields in most
examples, and troublesome chemical managing processes.
Recently we successfully synthesised the target molecular
using NaH as base at room temperature and the yields were
raised apparently, but NaH was too dangerous to come into
use in large scale.5 For these reasons, the development of
convenient, general, efficient and green methodologies for the
synthesis of N-alk-2'-enoyl cyclic imides is highly desirable.
In recent times room temperature ionic liquids (RTLs) have
attracted increasing interest in the area of green chemistry.
RTLs containing imidazolium cations can act as a powerful
medium in some organic reactions to accelerate the reaction.6-12
RTLs include acidic, neutral and basic ionic liquids. The
acidic and neutral ionic liquids have been well recognised and
successfully applied in many organic reactions.13-17 However,
the related report about the basic ionic liquids was rare.
We now report the preparation of N-alk-2'-enoyl cyclic
imides from acid chloride with cyclic imides in basic ionic
liquids at room temperature. We chose [bmIm]+[OH]-
(1-methyl-3-butylimidazolium hydroxide) as base and reaction
media and obtained high yield of products (Scheme 1).
Compared with the method proposed before, the protocol was
efficient and green, the products were readily separated from
the ionic liquids and the yields of N-alk-2'-enoyl cyclic imides
were satisfactory(see Table 1).
O
O
[bmIm] +OH-
r.t.
R1
R2
R1
Cl
+
R2H
2
1
3
R1= Me, n-Pr, i-Pr, Ph, 4-NO 2C6H4, 3,4-(CH3O)2C6H3
O
O
O
O
R2= -N
-N
-N
-N
O
O
Scheme 1
downfield from the internal standard tetramethylsilane. Mass spectra
were recorded on a HP 5989B mass spectrometer. Elemental analyses
were carried out on a VarioEL III instrument.
General procedure for the preparation of (3a): To RTLs,
[bmIm]+OH–, (364.0 mg, 2.0 mmol) was added succinimide
(99.0 mg, 1.0 mmol), then the reaction mixture was stirred at room
temperature for 1 h and crotonoyl chloride(104.5 mg, 1.0 mmol)
was added dropwise over 15 min. After that, the reaction mixture
was stirred for 2 h. The reaction mixture was extracted with ether
(3 ¥ 10 ml). The ether layer was separated and the product was
further purified by column chromatography (3:1, petroleum ether/
ethyl acetate), yield: 87%.
N-crotonoylsuccinimide (3a): White solid, m.p.109–111°C
(lit2.108–109°C); IR (KBr) 1731, 1692, 1440, 1416, 1331, 969
cm-1; 1H NMR (CDCl3) d:1.99 (dd, J = 1.7, 7.2 Hz, 3H), 2.82
(t, 4H), 6.42 (dd, J = 1.7, 15.4 Hz, 1H), 7.22–7.26 (m, 1H); 13C NMR
(CDCl3): d:19.1, 29.0, 125.0, 150.6, 164.4, 174.3, 175.0; MS m/z:
168 (M+ + 1, 6.66%), 69 (Base peak); Anal. Calcd for C8H9NO3:
C, 57.48; H, 5.43; N, 8.38. Found: C,57.54; H,5.26; N, 8.45%.
N-crotonoylphthalimide (3b): White solid, m.p.124–126°C;
IR (KBr) 1744, 1685, 1638, 1466, 1446, 958 cm-1; 1H NMR (CDCl3):
d:1.95 (d, J = 7.0 Hz, 3H), 6.68 (d, J = 15.2 Hz, 1H), 7.20–7.27(m,
1H), 7.77 (dd, J = 2.6, 5.2 Hz, 2H), 7.91 (dd, J = 2.8, 5.2 Hz, 2H);
13C NMR (CDCl3): d:168.4,168.2,141.7, 134.0, 130.9,128.7,128.0,
123.7, 123.3,18.8; MS m/z: 215 (M+, 6.72%), 69 (Base peak); Anal.
Calcd for C12H9NO3: C, 66.97; H, 4.22; N, 6.51. Found: C,67.01;
H, 4.20; N, 6.57%.
In summary, we have developed a new protocol for the
preparation of the N-alk-2'-enoyl cyclic imides directly from
a,b-unsaturated carboxylic acid chlorides with cyclic imides
using a basic ionic liquid, [bmIm]+OH-, as base and reaction
media. Further studies of possible applications of the moisture
stable room temperature ionic liquids in the synthesis of acyl
derivatives are being actively pursued.
N-crotonoylpyrrolidin-2-one (3c): IR (film) 1736, 1680, 1639 cm-1;
1H NMR(CDCl3) d:1.94 (d, J = 6.6 Hz, 3H), 2.03 (m, 2H), 2.61 (t,
J = 8.1 Hz, 2H), 3.85 (t, J = 7.2 Hz, 2H), 7.11 (d, J = 15.5 Hz, 1H), 7.25
(m,1H); 13C NMR (CDCl3): d: 175.4, 166.0, 145.7, 123.4, 45.5,33.7,
18.2, 17.0; MS m/z: 153 (M+, 6.65%); Anal. Calcd for C8H11NO2: C,
62.73; H, 7.24; N, 9.14. Found: C, 62.47; H, 7.51; N, 9.20%.
N-crotonoylazepan-2-one (3d): IR (film) 1703, 1655, 1515,
Experimental
Reactions were carried out in a 10 ml flask equipped with a magnetic
stirrer with no special precaution in the fume cupboard. Melting
points were uncorrected. IR spectra were recorded on a Bruker
Vector 22 spectrometer with absorption in cm-1. 1H NMR spectra
were determined on a Bruker AC-400 (400 MHz) spectrometer with
CDCl3 as the solutions. Chemical shifts were expressed in ppm
1463, 968 cm-1; H NMR (CDCl3): d:1.71, 1.82 (m, 6H), 1.90 (dd,
1
J = 1.3, 6.6 Hz, 3H), 2.70–2.73 (m, 2H), 3.90 (t, J = 5.4 Hz, 2H),
6.70–6.73 (m, 1H), 6.94–7.02 (m, 1H); 13C NMR (CDCl3), d:178.1,
168.7, 142.9, 122.5, 43.6, 39.5, 29.3, 28.8, 23.8, 18.3; MS m/z:181
(M+, 20.65), 166 (base peak); Anal. Calcd for C10H15NO2: C, 66.27;
H, 8.34; N,7.73. Found: C,66.19; H, 8.35; N, 7.84%.
N-hex-2-enoylsuccinimide (3e): IR (film) 1803, 1734, 1695, 1632 cm-1;
1H NMR (CDCl3): d:0.94 (t, J = 7.5 Hz, 3H), 1.52 (m, 2H), 2.26 (m,
* Correspondent. E-mail: river0301@163.com

560 JOURNAL OF CHEMICAL RESEARCH 2008
Table 1 N-alk-2'-enoyl cyclic imides products and the yields
Entry
R1
R2
Products
Time/h
3
Yielda,b/%
87
O
1
Me
3a
N-
O
O
N-
2
Me
3b
3
78
O O
N-
3
4
Me
Me
3c
3
3
86
83
N-
3d
O
O
N-
5
n-Pr
3e
3
84
O
O
N-
6
7
n-Pr
n-Pr
3f
3
3
85
79
O
N-
3g
O
N-
8
9
i-Pr
Ph
3h
3i
3
5
81
85
O
N-
O
O
N-
10
Ph
3j
5
66
O
O
11
12
Ph
3k
3l
5
5
70
64
N-
O
N-
4-NO2C6H4
O O
13
3,4-(CH3O)2C6H3
3m
5
57
N-
aAll products were fully characterised by spectroscopic data(IR; 1HNMR; 13CNMR; MS).
bIsolated yield.
2H), 2.80 (s, 4H), 6.37 (d, J = 15.4 Hz, 1H), 7.21(dt, J = 15.9, 7.1 Hz,
1H); 13C NMR (CDCl3): d: 14.2, 21.6,29.2, 35.3, 123.8, 155.4, 164.7,
175.2; MS m/z: 195 (M+, 24.2%); Anal. Calcd for C10H13NO3: C,
61.53; H, 6.71; N, 7.18. Found: C, 61.60; H, 6.61; N, 7.21%.
N-(4-methylpent-2-enoyl)pyrrolidin-2-one (3h): IR (film)1742,
1674, 1634 cm-1; 1H NMR (CDCl3) d:1.08(d, J = 3.2 Hz, 3H),
1.09(d, J = 2.8 Hz, 3H), 2.08–2.00(m, 2H), 2.54–2.51(m, 1H), 2.62
(t, J = 8.0 Hz, 2H) 3.86(t, J = 7.6 Hz, 2H), 7.09 (dd, J = 6.8, 15.4
Hz, 1H), 7.21(d, J = 16.0 Hz, 1H); 13C NMR (CDCl3): d:175.4,
166.5, 156.7, 119.3, 45.6, 33.8, 31.2, 21.2, 17.0; MS m/z: 182(M+
+ 1,44.4%), 96(base peak); Anal. Calcd for C10H15NO2: C, 66.27;
H, 8.34; N,7.73. Found: C, 66.17; H, 8.31; N, 7.48%.
N-cinnamoylsuccinimide (3i): White solid, m.p.118–119°C
(lit2.119–120°C);IR(KBr):1794,1728,1684,1663,1447,1442,995cm-1;
1H NMR (CDCl3): d: 2.87 (s, 4H), 7.03 (d, J = 15.6 Hz, 1H), 7.38–7.46
(m, 3H), 7.59–7.63 (m, 2H), 7.92 (d, J = 15.6 Hz,1H); 13C NMR(CDCl3):
d: 176.2, 166.0, 147.7, 134.2, 131.9, 129.5, 129.2, 128.7, 128.5, 121.2,
29.4; MS m/z: 229 (M+, 9.89%). Anal. Calcd for C13H11NO3: C, 68.11;
H, 4.84; N, 6.11 Found: C, 67.80; H, 4.70; N, 6.10%.
N-hex-2-enoylpyrrolidin-2-one (3f): IR (film) 1737, 1679, 1634,
1
1357, 981 cm-1; H NMR (CDCl3) d: 0.94 (t, J = 7.4 Hz, 3H), 1.52
(m, 2H), 2.04 (m, 2H), 2.25 (m, 2H), 2.61(t, J = 8.1 Hz, 2H), 3.85
(t, J = 7.2 Hz, 2H), 7.08–7.15 (m, 1H), 7.22–7.29 (m, 1H); 13C NMR
(CDCl3) d:175.6, 166.2, 150.5, 122.0, 45.6, 34.1, 33.8, 21.0, 17.0,
13.5; MS m/z: 181 (M+, 9.59%); Anal. Calcd for C10H15NO2: C,
66.27; H, 8.34; N,7.73. Found: C,66.17; H, 8.41; N, 7.79%.
N-hex-2-enoylazepan-2-one (3g): IR (film) 1787, 1729, 1646,
1462, 1378, 977 cm-1; 1H NMR (CDCl3) d: 0.95 (t, J = 7.4 Hz, 3H),
1.49–1.53 (m, 2H), 1.70–1.79 (m, 6H), 2.17–2.22 (m, 2H), 2.72 (t,
J = 6.4 Hz, 2H), 3.90 (t, J = 5.4 Hz, 2H), 6.70(dd, J = 1.4, 15.6 Hz,
1H), 6.94–7.01 (m, 1H); 13C NMR (CDCl3) d: 178.0, 169.0, 147.9,
124.9, 43.6, 39.6, 34.5, 29.3, 28.6, 23.7, 21.4, 13.7; MS m/z: 209
(M+, 23.54), 166 (base peak); Anal. Calcd for C12H19NO2: C, 68.87;
H, 9.15; N, 6.69. Found: C,68.77; H, 9.20; N, 6.83%.
N-cinnamoylphthalimide (3j): White solid, m.p.119–120°C
(lit18.101–102°C); IR(KBr): 1794, 1739, 1677, 1614, 1505, 986
1
cm-1; H NMR (CDCl3): d: 7.38–7.44 (m, 4H), 7.64–7.66 (m, 2H),
7.85–7.87 (m, 2H), 7.97–8.01 (m, 3H); 13C NMR(CDCl3): d:165.5,

JOURNAL OF CHEMICAL RESEARCH 2008 561
163.6, 147.7, 135.3, 134.0, 131.1, 131.0, 128.8, 128.7, 124.3, 119.3;
MS m/z: 277(M+, 9.54%); Anal. Calcd for C17H11NO3: C, 73.64; H,
3.99; N, 5.05. Found: C,73.48; H, 3.88; N, 5.07%.
Received 11 March 2008 ; accepted 7 August 2008
Paper 08/5286 doi: 10.3184/030823408X356305
Published online: 8 October 2008
N-cinnamoylpyrrolidin-2-one (3k): White solid, m.p.101–102°C
(lit.2 101–102°C); IR (KBr): 1769, 1701, 1631, 1495, 1450, 1422 cm-1;
1H NMR (CDCl3): d: 2.08 (tt, J = 6.8 Hz, 7.2 Hz, 2H), 2.66 (t,
J = 6.8 Hz, 2H), 3.93 (t, J = 7.2 Hz, 2H), 7.38–7.41 (m, 3H), 7.61–
7.64 (2H, m), 7.84, 7.95 (AB, J = 15.9 Hz, 2H); 13C NMR (CDCl3)
d:17.2, 34.0, 45.9,119.0, 128.5, 128.8, 130.3, 134.9, 145.5, 166.3,
175.7; MS m/z: 215 (M+, 9.59%); Anal. Calcd for C13H13NO2: C,
72.54; H, 6.09; N, 6.51. Found: C,72.47; H, 6.11; N, 6.62%.
N-(3-(4-nitrophenyl)acryloyl)phthalimide (3l): Pale yellow solid,
m.p. 215–217°C; IR (KBr): 1797, 1739, 1619, 1593, 1516, 1412,
1342, 863 cm-1; 1H NMR (CDCl3): d: 7.57(d, J = 15.6 Hz, 1H), 7.80
(d, J = 8.3 Hz, 2H), 7.89 (t, J = 2.6 Hz, 2H), 7.98(d, J = 15.9 Hz, 1H),
8.02(d, J = 3.1 Hz, 2H), 8.29(d, J = 8.1 Hz, 2H); 13C NMR(CDCl3):
d:165.9, 163.7, 148.7, 143.0, 140.8, 136.1, 131.6, 130.0, 125.2, 124.6,
124.5, 124.3; MS m/z: 322 (M+, 28.28%), 102 (Base peak); Anal.
Calcd for C17H10N2O5: C, 63.36; H, 3.13; N, 8.69. Found: C,63.27;
H, 3.17; N, 8.74%.
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N-(3-(3,4-dimethoxyphenyl)acryloyl)pyrrolidin-2-one (3m): White
solid, m.p.147–148°C; IR(KBr): 1638, 1597, 1513, 1445, 1349 cm-1;
1H NMR (CDCl3) d: 2.05–2.10(m, 2H), 2.66(t, J = 8.0 Hz, 2H),
3.95–3.90(m, 8H), 6.87(d, J = 8.2 Hz, 1H), 7.14(d, J = 1.2 Hz, 1H),
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191(base peak); Anal. Calcd for C15H17NO4: C, 65.44; H, 6.22; N,
5.09. Found: C, 65.29; H, 6.22; N, 5.20%.
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