Synthesis of functionalized 2-pyrrolidinones via domino reactions of arylamines, ethyl glyoxylate and acetylenedicarboxylates

Article abstract of DOI:10.1016/j.tet.2012.11.018

An efficient and practical synthetic method for the functionalized 2-pyrrolidinones was successfully developed via the domino reactions of ethyl glyoxylate and acetylenedicarboxylate with 2 M arylamines in the presence of benzoic acid as catalyst. When tw

Full text of DOI:10.1016/j.tet.2012.11.018

Tetrahedron 69 (2013) 589e594
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Synthesis of functionalized 2-pyrrolidinones via domino reactions of
arylamines, ethyl glyoxylate and acetylenedicarboxylates
*
Hong Gao, Jing Sun, Chao-Guo Yan
College of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou 225002, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 31 July 2012
Received in revised form 15 October 2012
Accepted 6 November 2012
Available online 13 November 2012
An efficient and practical synthetic method for the functionalized 2-pyrrolidinones was successfully
developed via the domino reactions of ethyl glyoxylate and acetylenedicarboxylate with 2 M arylamines
in the presence of benzoic acid as catalyst. When two kinds of amines were used in the reaction, the
stronger nucleophilic aliphatic amine preferentially added to acetylenedicarboxylate to form the reactive
intermediate
b
-enamino ester and the reaction showed high regioselectivity.
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Pyrrolidinone
Electron-deficient alkyne
b
-Enamino ester
Domino reaction
1. Introduction
biologically active heterocyclic compounds,23 here we wish to
report the results of the one-pot domino reaction of arylamines,
acetylenedicarboxylates and ethyl glyoxylate.
Pyrrole and its derivatives are the important structural motifs
that are widely present in numerous natural products, synthetic
pharmaceuticals and molecular metarials.1,2 As a consequence,
versatile synthetic methods have been developed for the syn-
thesis of these privileged molecules.3,4 Recently, The multicom-
ponent reactions containing active Huisgen’s 1,4-dipoles, which
were generated in situ from the addition of nucleophiles to
electron-deficient alkynes, have become one of the efficient
methods for preparation diverse substituted pyrroles.5e8 As for
some examples, Huisgen’s 1,4-dipoles derived from additions of
alkyl(aryl) isocyanides to dimethyl acetylenedicarboxylate reacted
with succinimide,9 cyclobutene-1,2-diones,10 benzoyl chloride11
all resulted in functionalized pyrroles. Triarylphosphine induced
domino reactions of acetylenedicarboxylates with some un-
saturated compounds12e15 and tertiary amines as well as other
catalyst assisted domino reactions16e20 are also efficient synthetic
methods for the functionalized pyrroles. Very recently, Jiang re-
ported three-component reactions of aromatic aldehydes, aryl-
amines and acetylenedicarboxylates to give 3-arylamino-2-
pyrrolidinones.21 We also found that this three-component re-
action could afford novel 3-hydroxyl or 3-arylamino-2-
pyrrolidinones and 2-hydroxytetrahydropyridines under differ-
ent condition.22 In order to establish the scope and limitation of
this reaction and develop efficient routes for the preparation of
2. Results and discussion
Initial studies were carried out by reactions of p-methylaniline,
dimethyl acetylenedicarboxylate and ethyl glyoxylate in ethanol
with p-toluenesulfonic acid as catalyst according to our previously
established reaction condition.22 After workup, we were satisfied to
find that the expected 3-arylamino-2-pyrrolidinone 1b (Table 1,
entry 2) was obtained in 50% yield. When acetic acid was used as
catalyst, the yield of 1b was increased to 55% yield. But benzoic acid
could afford 1b in 70% yield. If increasing of amount of benzoic acid
from 0.5 to 1.5 M, the yields of products were nearly same. Thus
benzoic acid proved to be the catalyst of choice and it was adopted
for all future studies. With the optimal conditions in hand, we then
examined the scope of the one-pot three-component reaction. At
first various arylamines were employed in the reaction (Table 1,
entries 1e6). It can be seen that all of the reactions proceeded
smoothly to afford the corresponding 2-pyrrolidinones 1aef in
good yields. Arylamines with electron-donating methyl, methoxyl
groups and weak electron-withdrawing chloro groups reacted ef-
ficiently to yield the desired products. Diethyl acetylenedicarbox-
ylate could also be successfully used in the reaction and the
expected products 1gej were obtained in relatively lower yields
(Table 1, entries 7e10). The structures of the functionalized 2-
pyrrolidinones were fully characterized by 1H and 13C NMR,
HRMS, IR spectra, and were further confirmed by single crystal X-
* Corresponding author. E-mail address: cgyan@yzu.edu.cn (C.-G. Yan).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.11.018

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H. Gao et al. / Tetrahedron 69 (2013) 589e594
Table 1
Synthesis of the functionalized 2-pyrrolidinones 1aeka
ArHN
CO R
CO R
2
2
PhCO H
2
2 ArNH
+
OHCCO C H
+
5
2
2
2
C H O H
CO C H
5
2
5
2
2
O
N
CO R
2
Ar
Entry
Compd
Ar
R
Yield (%)b
1
2
3
4
5
6
7
8
9
10
1a
1b
1c
1d
1e
1f
1g
1h
1i
p-CH3OC6H4
p-CH3C6H4
m-CH3C6H4
C6H5
CH3
CH3
CH3
CH3
CH3
CH3
C2H5
C2H5
C2H5
C2H5
72
70
50
64
55
58
70
45
70
47
p-ClC6H4
m-ClC6H4
p-CH3OC6H4
p-CH3C6H4
p-ClC6H4
1j
m-ClC6H4
a
Reaction conditions: amine (4.0 mmol), alkyne (2.0 mmol), ethyl glyoxylate (2.0 mmol) benzoic acid (0.5 mmol) in ethanol (10 mL) at rt for 48 h.
Isolated yield.
b
ray diffraction studies performed on compounds 1a and 1g (Figs. 1
and 2).
To explain the mechanism of this one-pot three-component
imine (B) gave the intermediate (C). Then the intramolecular nu-
cleophilic addition of amino group to carbonyl group in adduct (B)
produced a cyclic intermediate (C). At last the intramolecular re-
action of arylamino group to carbonyl group in ester moiety in
intermediate (C) with the elimination of methanol gave the final
polysubstituted 3-arylamino-2-pyrrolidinones 1. In this proposed
reaction mechanism 2 M anilines reacted with other two substrates
reaction, a plausible reaction course was proposed based on the
previously reported reactions,21,22 which is illustrated in Scheme 1.
The first reaction is the formation of active b-enamino ester (A) by
the addition of arylamine to acetylenedicarboxylate. The second
reaction is the formation of imine (B) from the condensation of
arylamine with ethyl glyoxylate with the catalysis of p-toluene-
to form the b-enamino ester (A) and the imine (B) intermediates.
sulfonic acid. Thirdly Michael addition of b-enamino ester (A) to
Fig. 1. Molecular structure of 2-pyrrolidinone 1a.
Scheme 1. Formation mechanism of 2-pyrrolidinone.
Having established an efficient route to the polysubstituted 2-
pyrrolidinones, we next turned our attention to examine the re-
actions containing two different kinds of amines. At first one aryl-
amine and one aliphatic amine, such as benzylamine were
introduced in the reaction with a one-pot domino procedure. Thus
benzylamine firstly reacted with dimethyl acetylenedicarboxylate
in ethanol at room temperature for 10 min for the formation of the
active intermediate b-enamino ester. Then one molar arylamine
and ethyl glyoxylate as well as benzoic acid was added. The reaction
proceeded smoothly at room temperature for 24 h to give the de-
sired 2-pyrrolidinones 2aeg in good yield (Table 2, entries 1e7).
Fig. 2. Molecular structure of 2-pyrrolidinone 1g.

H. Gao et al. / Tetrahedron 69 (2013) 589e594
591
Table 2
Synthesis of the polysubstituted 2-pyrrolidinones 2aeoa
Entry
Compd
R
Ar
Yield (%)b
1
2
3
4
5
6
7
8
2a
2b
2c
2d
2e
2f
2g
2h
2i
2j
2k
2l
2m
2n
2o
CH2C6H5
CH2C6H5
CH2C6H5
CH2C6H5
CH2C6H5
CH2C6H5
CH2C6H5
CH2CH2C6H5
CH2CH2C6H5
CH2CH2C6H5
CH(CH3)C6H5
CH(CH3)C6H5
CH(CH3)C6H5
p-ClC6H4
p-CH3C6H4
p-CH3OC6H4
C6H5
p-ClC6H4
p-BrC6H4
p-CH3C6H4
p-CH3OC6H4
p-CH3C6H4
p-CH3OC6H4
p-ClC6H4
p-CH3C6H4
p-CH3OC6H4
p-ClC6H4
75
65
50
45
40
55
70
66
58
43
55
60
35
40
60
9
10
11
12
13
14
15
p-CH3C6H4
p-ClC6H4
p-CH3OC6H4
a
Reaction conditions: amine (2.0 mmol), alkyne (2.0 mmol) in ethanol at rt for 10 min; then ethyl glyoxylate (2.0 mmol), arylamine (2.0 mmol), benzoic acid (0.5 mmol) for
48 h.
b
Isolated yield.
Then the similar reactions containing 2-phenylethylamine or 1-
phenylethylamine also successfully resulted in the expected 2-
pyrrolidinones in moderate yields 2hem (Table 2, entries 8e13).
If two arylamines having substituents with larger different electron
effects were employed in the reaction by using above sequential
procedure, the desired 2-pyrrolidinones 2n and 2o were also suc-
cessfully prepared in lower yields (Table 2, entries 8e13). On other
cases we found that a mixture of two kinds of polysubstituted 2-
pyrrolidinones would be formed and this mixture is very difficult
to separate and gave nearly same analytical data, which was clearly
could be employed in the reaction to give more substituted 2-
pyrrolidinones. We also proposed rational reaction mechanisms
and established the scope and limitation of this reaction, which
enabled further modification that led to molecular diversity. The
potential uses of the reaction in synthetic and medicinal chemistry
might be quite significant.
3. Experimental section
3.1. Typical procedure for the preparation of functionalized
2-pyrrolidinones 1aej
caused by the reversible equilibrium reaction of formations of b-
enamino ester and arylimine and their sequential cross re-
actions.24,25 Taken together, these one-pot sequential reactions
provided fifteen new 2-pyrrolidinone derivatives, of which the
compound 2d was characterized by X-ray crystallography (Fig. 3).
A mixture of arylamine (4.0 mmol) and acetylenedicarboxylate
(2.0 mmol) in 5.0 mL ethanol was stirred at room temperature for
10 min. Then ethyl glyoxylate (2.0 mmol, 50% soln in toluene,
0.45 g) and benzoic acid (0.5 mmol, 0.060 g) were added to it. The
solution was stirred at room temperature for two days. The
resulting precipitates were collected by filtration and washed with
cold alcohol to give the pure product.
Compound 1a: light yellow solid, 72%, mp 122e123 ꢀC; 1H NMR
(600 MHz, CDCl3)
d
: 8.27 (s,1H, NH), 7.44 (d, J¼9.0 Hz, 2H, ArH), 7.13
(d, J¼9.0 Hz, 2H, ArH), 6.88 (d, J¼9.0 Hz, 2H, ArH), 6.85 (d, J¼8.4 Hz,
2H, ArH), 5.32 (s, 1H, CH), 4.17e4.12 (m, 1H, CH), 4.10e4.05 (m, 1H,
CH), 3.80 (s, 3H, OCH3), 3.79 (s, 3H, OCH3), 3.73 (s, 3H, CH3), 1.11 (t,
J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.6, 164.6, 163.6,
157.9, 157.5, 145.0, 130.9, 129.4, 125.5, 124.1, 114.2, 113.6, 100.5, 62.1,
61.8, 55.4, 51.3, 14.0; IR (KBr) n: 3305, 2950, 2836, 2064, 1713, 1632,
1511, 1462, 1382, 1302, 1243, 1186, 1109, 1029, 875, 830, 761 cmꢁ1
;
MS (m/z): 903.09 ([2MþNa]þ) 100%. HRMS (ESI) calcd for
C
23H23N2O7 ([MꢁH]þ): 439.1511. Found: 439.1512.
Fig. 3. Molecular structure of 2-pyrrolidinone 2d.
Compound 1b: light yellow solid, 70%, mp 139e141 ꢀC; 1H NMR
(600 MHz, CDCl3)
d
: 8.27 (s, 1H, NH), 7.45 (d, J¼9.0 Hz, 2H, ArH), 7.16
(d, J¼8.4 Hz, 2H, ArH), 7.12 (d, J¼8.4 Hz, 2H, ArH), 7.07 (d, J¼8.4 Hz,
2H, ArH), 5.38 (s, 1H, CH), 4.17e4.05 (m, 2H, CH2), 3.73 (s, 3H, CH3),
2.34 (s, 3H, CH3), 2.32 (s, 3H, CH3), 1.11 (t, J¼6.9 Hz, 3H, CH3); 13C
In summary we were successfully developed a one-pot domino
reaction of arylamine, ethyl gloxylate and acetylenedicarboxylate
and provided a convenient procedure for the preparation of the
functionalized 2-pyrrolidinones in good yields. Furthermore, by
using one-pot sequential reaction procedure, two kinds of amines
NMR (150 MHz, CDCl3) d: 168.5, 164.6, 163.5, 136.1, 135.2, 135.2,
134.0, 129.7, 129.0, 123.7, 121.9, 101.3, 61.9, 61.8, 51.7, 21.0, 20.9, 14.0;
IR (KBr) : 3247, 2969,1744,1695,1520,1445, 1366,1249,1199,1134,
n

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H. Gao et al. / Tetrahedron 69 (2013) 589e594
1026, 938, 817 cmꢁ1; MS (m/z): 839.20 ([2MþNa]þ) 100%. HRMS
(ESI) calcd for C23H23N2O5 ([MꢁH]þ): 407.1612. Found: 407.1612.
Compound 1c: light yellow solid, 50%, mp 106e109 ꢀC; 1H NMR
3337, 3286, 3045, 2987, 2920, 2867, 2591, 1905, 1718, 1641, 1514,
1462, 1402, 1363, 1290, 1245, 1183, 1111, 1027, 946, 888, 814,
761 cmꢁ1; MS (m/z): 867.06 ([2MþNa]þ) 100%. HRMS (ESI) calcd for
(600 MHz, CDCl3)
d
: 8.24 (s, 1H, NH), 7.46 (s, 1H, ArH), 7.34 (d,
C
24H25N2O5 ([MꢁH]þ): 421.1769. Found: 421.1765.
J¼8.4 Hz, 1H, ArH), 7.24e7.19 (m, 2H, ArH), 7.01 (t, J¼9.6 Hz, 4H,
Compound 1i: light yellow solid, 70%, mp 119e121 ꢀC; 1H NMR
ArH), 5.40 (s, 1H, CH), 4.14e4.10 (m, 2H, CH2), 3.72 (s, 3H, CH3), 2.34
(600 MHz, CDCl3)
d
: 8.30 (s, 1H, NH), 7.56 (d, J¼8.4 Hz, 2H, ArH),
(s, 6H, CH3), 1.11 (t, J¼8.4 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d
:
7.34 (d, J¼8.4 Hz, 2H, ArH), 7.28 (d, J¼9.0 Hz, 2H, ArH), 7.11 (d,
J¼8.4 Hz, 2H, ArH), 5.39 (s, 1H, CH), 4.26e4.18 (m, 2H, CH2),
4.15e4.11 (m, 2H, CH2), 1.25 (t, J¼6.9 Hz, 3H, CH3), 1.15 (t, J¼7.2 Hz,
168.5, 164.5, 163.6, 144.5, 139.1, 138.3, 137.8, 136.5, 128.9, 128.2,
127.1, 126.2, 124.2, 122.7, 120.8, 118.9, 102.0, 61.9, 61.8, 51.4, 21.5,
21.4, 14.0; IR (KBr)
n
: 3234, 3080, 2968, 1739, 1694, 1651, 1594, 1549,
3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.1, 164.0, 163.5, 143.9,
1492, 1447, 1395, 1357, 1276, 1199, 1024, 896, 786 cmꢁ1; MS (m/z):
407.29 ([Mꢁ1]þ) 100%. HRMS (ESI) calcd for C23H23N2O5 ([MꢁH]þ):
407.1612. Found: 407.1613.
136.4, 135.1, 131.6, 130.7, 129.3, 128.6, 124.7, 122.8, 103.5, 62.2, 61.6,
60.7, 14.1, 14.0; IR (KBr) : 3470, 3229, 3121, 3063, 2983, 1904, 1743,
n
1697, 1637, 1595, 1542, 1493, 1379, 1334,1286, 1216, 1099, 1033, 889,
827, 772 cmꢁ1; MS (m/z): 461.27 ([Mꢁ1]þ) 100%. HRMS (ESI) calcd
for C22H19Cl2N2O5 ([MꢁH]þ): 461.0677. Found: 461.0672.
Compound 1d: light yellow solid, 64%, mp 109e111 ꢀC; 1H NMR
(600 MHz, CDCl3)
7.35 (d, J¼15.0 Hz, 4H, ArH), 7.19 (d, J¼2.4 Hz, 4H, ArH), 5.42 (s, 1H,
CH), 4.14e4.09 (m, 2H, CH2), 3.71 (s, 3H, CH3), 1.10 (s, 3H, CH3); 13
NMR (150 MHz, CDCl3) : 168.4, 164.5, 163.7, 144.3, 138.0, 136.6,
129.2, 128.4, 126.3, 125.4, 123.5, 121.9, 102.2, 62.0, 61.8, 58.4, 51.4,
18.4, 14.0, 13.9; IR (KBr) : 3289, 3063, 2986, 1741, 1717, 1672, 1639,
d: 8.28 (s, 1H, NH), 7.59 (d, J¼2.7 Hz, 2H, ArH),
Compound 1j: white solid, 47%, mp 99e101 ꢀC; 1H NMR
C
(600 MHz, CDCl3) d: 8.28 (s, 1H, NH), 7.74 (s, 1H, ArH), 7.54 (t,
d
J¼8.1 Hz, 1H, ArH), 7.33 (t, J¼8.1 Hz, 1H, ArH), 7.26 (d, J¼7.8 Hz, 1H,
ArH), 7.21 (t, J¼3.9 Hz, 1H, ArH), 7.20e7.17 (m, 2H, ArH), 7.10e7.08
(m, 1H, ArH), 5.42 (s, 1H, CH), 4.28e4.15 (m, 4H, CH2), 1.26 (t,
J¼6.9 Hz, 3H, CH3), 1.18 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz,
n
1594, 1498, 1470, 1452, 1370, 1300, 1251, 1230, 1201, 1119, 1019, 919,
817, 763 cmꢁ1; MS (m/z): 379.31 ([Mꢁ1]þ) 100%. HRMS (ESI) calcd
for C21H19N2O5 ([MꢁH]þ): 379.1299. Found: 379.1301.
CDCl3) d: 168.0, 163.9, 143.4, 139.1, 137.7, 135.0, 134.1, 130.2, 129.4,
126.3, 123.4, 121.6, 121.5, 119.3, 104.3, 62.3, 61.6, 60.8, 14.1, 14.0; IR
(KBr) : 3464, 3238, 3121, 3070, 2982, 2913, 1743, 1697, 1636, 1590,
Compound 1e: white solid, 55%, mp 164e165 ꢀC; 1H NMR
n
(600 MHz, CDCl3)
d
: 8.30 (s, 1H, NH), 7.55 (d, J¼8.4 Hz, 2H, ArH),
1541, 1480, 1393, 1333, 1296, 1212, 1120, 1034, 929, 872, 781 cmꢁ1
;
7.35 (d, J¼8.4 Hz, 2H, ArH), 7.29 (d, J¼9.0 Hz, 2H, ArH), 7.11 (d,
J¼9.0 Hz, 2H, ArH), 5.38 (s, 1H, CH), 4.19e4.16 (m, 1H, CH),
4.12e4.09 (m, 1H, CH), 3.76 (s, 3H, CH3), 1.13 (t, J¼6.9 Hz, 3H, CH3);
MS (m/z): 461.25 ([Mꢁ1]þ) 100%. HRMS (ESI) calcd for
C
22H19Cl2N2O5 ([MꢁH]þ): 461.0677. Found: 461.0676.
13C NMR (150 MHz, CDCl3)
d: 168.0, 164.3, 163.4, 144.1, 136.3, 135.1,
3.2. Typical procedure for the preparation of functionalized
131.7, 130.8, 129.3, 128.6, 124.9, 122.8, 102.9, 62.2, 61.5, 51.6, 14.0; IR
2-pyrrolidinones 2aeo
(KBr) n: 3243, 3121, 3070, 2992, 1743, 1698, 1652, 1592, 1542, 1452,
1363, 1291, 1211, 1095, 1019, 939, 882, 831 cmꢁ1; MS (m/z): 447.30
([Mꢁ1]þ) 100%. HRMS (ESI) calcd for C21H17Cl2N2O5 ([MꢁH]þ):
447.0520. Found: 447.0522.
In a round bottom flask a mixture of aliphatic amine or aryl-
amine (2.0 mmol) and acetylenedicarboxylate (2.0 mmol) in 5.0 mL
ethanol was stirred at room temperature for 10 min. Then aryl-
amine (2.0 mmol), ethyl glyoxylate (2.0 mmol, 50% soln in toluene,
0.45 g) and benzoic acid (0.5 mmol, 0.060 g) were added to it. The
solution was stirred at room temperature for two days. The
resulting precipitates were collected by filtration and washed with
cold alcohol to give the pure product.
Compound 1f: white solid, 58%, mp 110e112 ꢀC; 1H NMR
(600 MHz, CDCl3) d: 8.27 (s, 1H, NH), 7.72 (s, 1H, ArH), 7.50 (d,
J¼7.8 Hz, 1H, ArH), 7.31 (t, J¼8.1 Hz, 1H, ArH), 7.24 (s, 1H, ArH),
7.20e7.17 (m, 3H, ArH), 7.07 (d, J¼7.8 Hz, 1H, ArH), 5.40 (s, 1H, CH),
4.21e4.13 (m, 2H, CH2), 3.77 (s, 3H, CH3), 1.15 (t, J¼7.2 Hz, 3H, CH3);
13C NMR (150 MHz, CDCl3)
d
: 167.9, 164.2, 163.4, 143.7, 139.0, 137.7,
Compound 2a: white solid, 75%, mp 100e102 ꢀC; 1H NMR
135.0, 134.0, 130.2, 129.4, 126.3, 125.5, 123.6, 121.7, 121.6, 119.2,
103.7, 62.3, 61.5, 51.7, 14.0; IR (KBr) : 3390, 3242, 3120, 3073, 2977,
(600 MHz, CDCl3)
d
: 7.43 (d, J¼8.4 Hz, 2H, ArH), 7.34 (d, J¼4.8 Hz,
n
4H, ArH), 7.29e7.26 (m, 1H, ArH), 7.18 (d, J¼8.4 Hz, 2H, ArH), 5.29 (s,
1H, CH), 5.21 (s, 1H, CH), 5.05 (d, J¼15.0 Hz, 1H, CH), 4.14e4.09 (m,
1H, CH), 4.07e4.01 (m, 1H, CH), 3.74 (s, 3H, CH3), 2.33 (s, 3H, CH3),
2388, 1961, 1735, 1699, 1652, 1590, 1541, 1480, 1441, 1393, 1355,
1266, 1210, 1021, 939, 889, 850, 789 cmꢁ1; MS (m/z): 447.25
([Mꢁ1]þ) 100%. HRMS (ESI) calcd for C21H17Cl2N2O5 ([MꢁH]þ):
447.0520. Found: 447.0517.
1.09 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.9,
136.3, 134.0, 129.7, 128.7, 127.6, 127.5, 122.3, 61.7, 51.1, 21.0, 14.0; IR
Compound 1g: light yellow solid, 70%, mp 119e121 ꢀC; 1H NMR
(KBr) n: 3476, 3327, 3060, 2995, 2922, 2322, 1942, 1752, 1704, 1643,
(600 MHz, CDCl3)
d
: 8.27 (s,1H, NH), 7.44 (d, J¼9.0 Hz, 2H, ArH), 7.13
1515, 1449, 1371, 1303, 1239, 1109, 1025, 970, 922, 816, 766 cmꢁ1
;
(d, J¼8.4 Hz, 2H, ArH), 6.88 (d, J¼9.0 Hz, 2H, ArH), 6.85 (d, J¼8.4 Hz,
2H, ArH), 5.33 (s, 1H, CH), 4.25e4.16 (m, 2H, CH2), 4.12e4.08 (m, 2H,
CH2), 3.80 (s, 3H, OCH3), 3.79 (s, 3H, OCH3), 1.23 (t, J¼6.9 Hz, 3H,
HRMS (ESI) calcd for C23H23N2O5 ([MꢁH]þ): 407.1612. Found:
407.1610.
Compound 2b: yellow solid, 65%, mp 138e141 ꢀC; 1H NMR
CH3), 1.12 (t, J¼6.9 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.7,
(600 MHz, CDCl3)
d
: 8.29 (s, 1H, NH), 7.56 (d, J¼9.0 Hz, 2H, ArH),
164.4, 163.6, 157.9, 157.4, 144.9, 130.9, 129.4, 125.4, 124.2, 114.3,
7.32 (d, J¼9.0 Hz, 2H, ArH), 7.13 (d, J¼9.0 Hz, 2H, ArH), 6.86 (d,
J¼9.0 Hz, 2H, ArH), 5.36 (s,1H, CH), 4.18e4.15 (m,1H, CH), 4.11e4.08
(m, 1H, CH), 3.81 (s, 3H, OCH3), 3.75 (s, 3H, CH3), 1.13 (t, J¼7.2 Hz,
113.6, 101.0, 62.2, 61.8, 60.3, 55.4, 14.2, 14.0; IR (KBr)
n: 3464, 3405,
3287, 2985, 2923, 2836, 2550, 2057, 1893, 1742, 1713, 1633, 1511,
1459, 1377, 1303, 1243, 1183, 1109, 1030, 946, 879, 832, 761 cmꢁ1
;
3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.3, 164.7, 163.5, 157.7,
MS (m/z): 931.02 ([2MþNa]þ) 100%. HRMS (ESI) calcd for
145.0, 135.3, 131.4, 130.6, 129.2, 125.8, 125.6, 124.2, 122.8, 114.3,
113.7, 113.6, 100.7, 62.1, 61.4, 58.5, 55.4, 51.5, 14.0; IR (KBr) : 3251,
3056, 2987, 2839, 1699, 1640, 1503, 1449, 1376, 1297, 1220, 1114,
1032, 937, 830, 779 cmꢁ1; MS (m/z): 443.36 ([Mꢁ1]þ) 100%. HRMS
(ESI) calcd for C22H20ClN2O6 ([MꢁH]þ): 443.1015. Found: 443.1015.
Compound 2c: white solid, 50%, mp 77e79 ꢀC; 1H NMR
C
24H25N2O7 ([MꢁH]þ): 453.1667. Found: 453.1663.
n
Compound 1h: white solid, 45%, mp 144e146 ꢀC; 1H NMR
(600 MHz, CDCl3)
d
: 8.25 (s,1H, NH), 7.46 (d, J¼8.4 Hz, 2H, ArH), 7.16
(d, J¼7.8 Hz, 2H, ArH), 7.11 (d, J¼7.8 Hz, 2H, ArH), 7.07 (d, J¼8.4 Hz,
2H, ArH), 5.38 (s,1H, CH), 4.24e4.15 (m, 2H, CH2), 4.12e4.09 (m, 2H,
CH2), 2.33 (s, 3H, CH3), 2.32 (s, 3H, CH3), 1.22 (t, J¼7.2 Hz, 3H, CH3),
(600 MHz, CDCl3)
d
: 7.57 (d, J¼7.8 Hz, 2H, ArH), 7.39 (t, J¼8.4 Hz, 2H,
1.12 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d
: 168.6,
ArH), 7.35 (d, J¼4.8 Hz, 4H, ArH), 7.30e7.28 (m, 1H, ArH), 7.23 (t,
J¼7.8 Hz, 1H, ArH), 5.34 (s, 1H, CH), 5.24 (s, 1H, CH), 5.07e5.03 (m,
1H, CH), 4.15e4.10 (m, 1H, CH), 4.07e4.02 (m, 1H, CH), 3.75 (s, 3H,
164.2, 163.7, 144.5, 136.0, 135.4, 135.0, 134.1, 129.6, 129.0, 123.5,
121.9, 101.8, 61.9, 60.4, 21.0, 20.9, 14.1, 14.0; IR (KBr) n: 3464, 3414,

H. Gao et al. / Tetrahedron 69 (2013) 589e594
593
CH3), 1.08 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d
: 168.7,
1676, 1617, 1513, 1477, 1385, 1307, 1222, 1116, 1026, 915, 829,
757 cmꢁ1; HRMS (ESI) calcd for C24H25N2O6 ([MꢁH]þ): 437.1718.
Found: 437.1715.
136.5, 129.1, 128.7, 127.6, 127.5, 126.3, 122.1, 61.8, 51.1, 14.0; IR (KBr)
n
: 3465, 3356, 3074, 3026, 2941, 2046, 1956, 1743, 1680, 1618, 1497,
1448, 1371, 1291, 1231, 1122, 1021, 972, 899, 812, 757 cmꢁ1; HRMS
(ESI) calcd for C22H21N2O5 ([MꢁH]þ): 393.1456. Found: 393.1456.
Compound 2d: white solid, 45%, mp 111e113 ꢀC; 1H NMR
Compound 2j: white solid, 43%, mp 119e120 ꢀC; 1H NMR
(600 MHz, CDCl3)
d
: 7.53 (d, J¼8.4 Hz, 2H, ArH), 7.35 (d, J¼8.4 Hz,
2H, ArH), 7.31 (t, J¼7.8 Hz, 2H, ArH), 7.23 (t, J¼9.0 Hz, 3H, ArH), 5.26
(600 MHz, CDCl3)
d
: 7.55 (d, J¼8.4 Hz, 2H, ArH), 7.35 (d, J¼12.0 Hz,
(s, 1H, CH), 4.17e4.10 (m, 2H, CH2), 4.09e4.02 (m, 2H, CH2), 3.74 (s,
6H, ArH), 7.29 (d, J¼5.4 Hz, 1H, ArH), 5.30 (s, 1H, CH), 5.20 (d,
J¼2.4 Hz, 1H, CH), 5.06e5.03 (m, 1H, CH), 4.17e4.11 (m, 1H, CH),
4.09e4.04 (m, 1H, CH), 3.75 (s, 3H, CH3), 1.11 (t, J¼7.2 Hz, 3H, CH3);
3H, CH3), 2.92 (t, J¼7.2 Hz, 2H, CH2), 1.10 (t, J¼7.2 Hz, 3H, CH3); 13
C
NMR (150 MHz, CDCl3) d: 168.6, 138.4, 135.2, 131.5, 129.2, 128.9,
128.6, 126.5, 123.0, 61.8, 51.1, 14.0; IR (KBr) n: 3452, 3331, 3025,
13C NMR (150 MHz, CDCl3)
d
: 168.6, 135.2, 131.6, 129.3, 128.8, 127.5,
2950, 2401, 2317, 1883, 1740, 1676, 1619, 1487, 1380, 1306, 1223,
1089, 1018, 915, 826, 753 cmꢁ1; HRMS (ESI) calcd for C23H22ClN2O5
([MꢁH]þ): 441.1223. Found: 441.1221.
123.1, 61.9, 51.2, 14.0; IR (KBr) n: 3361, 3034, 2984, 2948, 1739, 1681,
1620, 1490, 1446, 1378, 1314, 1204, 1098, 1023, 970, 913, 849,
809 cmꢁ1; HRMS (ESI) calcd for C22H20ClN2O5 ([MꢁH]þ): 427.1066.
Found: 427.1066.
Compound 2k: light orange solid, 55%, mp 148e150 ꢀC; 1H
NMR (600 MHz, CDCl3)
d
: 7.38 (d, J¼6.6 Hz, 2H, ArH), 7.34e7.29
Compound 2e: white solid, 40%, mp 127e128 ꢀC; 1H NMR
(m, 4H, ArH), 7.22 (d, J¼6.6 Hz, 1H, ArH), 7.16 (d, J¼7.2 Hz, 2H,
ArH), 6.14 (s, 1H, CH), 5.25 (d, J¼21.6 Hz, 1H, CH), 4.10e4.02 (m,
2H, CH2), 3.76 (s, 3H, CH3), 2.31 (s, 3H, CH3), 1.59 (d, J¼6.6 Hz, 3H,
(600 MHz, CDCl3)
d
: 7.50 (s, 4H, ArH), 7.35 (d, J¼6.6 Hz, 4H, ArH),
7.29 (d, J¼6.0 Hz, 1H, ArH), 5.30 (s, 1H, CH), 5.19 (s, 1H, CH),
5.06e5.02 (m, 1H, CH), 4.16e4.12 (m, 1H, CH), 4.09e4.05 (m, 1H,
CH), 3.75 (s, 3H, CH3), 1.11 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz,
CH3), 1.07 (s, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.7, 136.2,
133.9, 129.7, 128.7, 128.6, 127.1, 125.9, 122.4, 61.7, 51.1, 24.3, 20.9,
14.0; IR (KBr) : 3457, 3327, 3022, 2974, 2927, 1931, 1740, 1699,
CDCl3)
d
: 168.5, 135.7, 132.2, 128.8, 127.5, 123.3, 119.4, 62.0, 51.2,
n
14.0; IR (KBr)
n
: 3458, 3360, 3032, 2982, 2948, 1927, 1739, 1681,
1623, 1515, 1454, 1381, 1311, 1202, 1116, 1021, 906, 807, 760 cmꢁ1
;
1619, 1487, 1446, 1378, 1315, 1203, 1116, 1061, 1020, 912, 845,
808 cmꢁ1; HRMS (ESI) calcd for C22H20BrN2O5 ([MꢁH]þ): 471.0197.
Found: 471.0230.
HRMS (ESI) calcd for C24H25N2O5 ([MꢁH]þ): 421.1769. Found:
421.1768.
Compound 2l: light yellow solid, 60%, mp 125e127 ꢀC; 1H NMR
Compound 2f: white solid, 55%, mp 98e100 ꢀC; 1H NMR
(600 MHz, CDCl3)
d
: 7.38 (d, J¼8.4 Hz, 2H, ArH), 7.34 (t, J¼6.6 Hz,
(600 MHz, CDCl3)
d
: 7.43 (d, J¼8.4 Hz, 2H, ArH), 7.35e7.32 (m, 4H,
2H, ArH), 7.32e7.27 (m, 2H, ArH), 7.22 (t, J¼7.2 Hz, 1H, ArH),
6.90e6.87 (m, 2H, ArH), 6.14 (s, 1H, CH), 5.21 (d, J¼22.2 Hz, 1H, CH),
4.13e4.06 (m, 1H, CH), 4.04e3.99 (m, 1H, CH), 3.79 (d, J¼4.8 Hz, 3H,
CH3O), 3.76 (s, 3H, CH3), 1.59e1.56 (m, 3H, CH3), 1.08 (t, J¼7.2 Hz,
ArH), 7.29e7.26 (m, 1H, ArH), 7.18 (d, J¼8.4 Hz, 2H, ArH), 5.30 (s, 1H,
CH), 5.21 (s, 1H, CH), 5.05 (t, J¼10.2 Hz, 1H, CH), 4.24e4.17 (m, 2H,
CH2), 4.09e4.05 (m, 2H, CH2), 2.33 (s, 3H, CH3), 1.27 (t, J¼7.2 Hz, 3H,
CH3), 1.10 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.9,
3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.7, 158.0, 129.3, 128.7,
136.2, 134.0, 129.7, 128.7, 127.6, 127.5, 122.3, 61.7, 60.0, 21.0, 14.4,
128.6, 127.1, 125.9, 125.8, 124.5, 114.3, 61.6, 55.4, 51.1, 24.3, 14.0; IR
(KBr) : 3456, 3325, 3070, 2973, 2930, 2840, 2045, 1741, 1698, 1622,
14.0; IR (KBr)
n
: 3473, 3312, 3053, 2983, 2917, 2322, 2087, 1753,
n
1704, 1645, 1513, 1450, 1368, 1302, 1237, 1108, 1028, 983, 921, 875,
813, 766 cmꢁ1; HRMS (ESI) calcd for C24H25N2O5 ([MꢁH]þ):
421.1769. Found: 421.1765.
1514, 1455, 1380, 1305, 1244, 1200, 1116, 1026, 906, 846, 808,
762 cmꢁ1; HRMS (ESI) calcd for C24H25N2O6 ([MꢁH]þ): 437.1718.
Found: 437.1718.
Compound 2g: light orange solid, 70%, mp 89e91 ꢀC; 1H NMR
Compound 2m: white solid, 35%, mp 156e158 ꢀC; 1H NMR
(600 MHz, CDCl3)
d
: 7.43 (d, J¼8.4 Hz, 2H, ArH), 7.34 (t, J¼6.6 Hz, 4H,
(600 MHz, CDCl3)
d
: 7.50 (d, J¼8.4 Hz, 2H, ArH), 7.33 (t, J¼6.6 Hz, 6H,
ArH), 7.29e7.27 (m, 1H, ArH), 6.91 (d, J¼8.4 Hz, 2H, ArH), 5.24 (d,
J¼19.2 Hz, 2H, CH2), 5.06e5.02 (m, 1H, CH), 4.24e4.17 (m, 2H, CH2),
4.09e4.06 (m, 2H, CH2), 3.80 (s, 3H, CH3O), 1.27 (t, J¼7.2 Hz, 3H,
ArH), 7.23 (d, J¼6.0 Hz, 1H, ArH), 6.09 (s, 1H, CH), 5.24 (s, 1H, CH),
4.12e4.10 (m, 1H, CH), 4.07e4.02 (m, 1H, CH), 3.77 (s, 3H, CH3), 1.59
(d, J¼6.6 Hz, 3H, CH3), 1.09 (t, J¼4.8 Hz, 3H, CH3); 13C NMR
CH3), 1.11 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3)
d
: 168.9,
(150 MHz, CDCl3)
d: 168.5, 135.2, 131.6, 129.2, 128.7, 127.2, 125.8,
158.0, 129.3, 128.7, 127.6, 127.5, 124.5, 114.4, 61.7, 59.9, 55.4, 14.3,
123.2, 61.9, 51.2, 24.4, 14.0; IR (KBr) n: 3456, 3331, 3088, 2975, 2928,
14.0; IR (KBr)
n
: 3452, 3340, 2981, 2934, 2839, 2048, 1736, 1704,
1785, 1711, 1681, 1624, 1489, 1379, 1309, 1203, 1116, 1021, 907, 848,
808, 761 cmꢁ1; HRMS (ESI) calcd for C23H22ClN2O5 ([MꢁH]þ):
441.1223. Found: 441.1223.
1684, 1620, 1515, 1450, 1382, 1301, 1246, 1196, 1117, 1085, 1030, 970,
812 cmꢁ1; HRMS (ESI) calcd for C24H25N2O6 ([MꢁH]þ): 437.1718.
Found: 437.1715.
Compound 2n: white solid, 40%, mp 139e141 ꢀC; 1H NMR
Compound 2h: light yellow solid, 66%, mp 126e127 ꢀC; 1H NMR
(600 MHz, CDCl3)
d
: 8.24 (s, 1H, NH), 7.44 (d, J¼8.4 Hz, 2H, ArH),
(600 MHz, CDCl3)
d: 7.41 (d, J¼7.8 Hz, 2H, ArH), 7.31 (t, J¼7.8 Hz, 2H,
7.24 (t, J¼8.1 Hz, 1H, ArH), 7.19e7.18 (m, 3H, ArH), 7.14 (d, J¼8.4 Hz,
1H, ArH), 7.07 (d, J¼7.8 Hz, 1H, ArH), 5.39 (s, 1H, CH), 4.16e4.08 (m,
2H, CH2), 3.74 (s, 3H, CH3), 2.33 (s, 3H, CH3), 1.12 (t, J¼6.9 Hz, 3H,
ArH), 7.25 (d, J¼4.2 Hz, 1H, ArH), 7.22 (t, J¼7.2 Hz, 2H, ArH), 7.18 (d,
J¼8.4 Hz, 2H, ArH), 5.26 (s, 1H, CH), 4.16e4.09 (m, 2H, CH2),
4.07e4.01 (m, 2H, CH2), 3.73 (s, 3H, CH3), 2.93 (t, J¼7.8 Hz, 2H, CH2),
2.33 (s, 3H, CH3), 1.09 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz,
CH3); 13C NMR (150 MHz, CDCl3)
d: 168.2, 164.3, 163.4, 143.9, 139.2,
136.4, 134.0, 133.8, 129.8, 129.7, 129.3, 129.0, 125.2, 123.7, 123.4,
122.1, 121.9, 121.5, 103.5, 62.1, 62.0, 51.6, 21.0, 14.0; IR (KBr) : 3468,
CDCl3)
d: 168.9, 138.5, 136.2, 134.0, 129.7, 129.0, 128.6, 126.5, 122.4,
n
61.7, 51.0, 21.0, 14.0; IR (KBr)
n
: 3458, 3331, 3028, 2953, 1953, 1887,
3297, 3059, 2969, 1797, 1748, 1714, 1645, 1587, 1516, 1468, 1370,
1296, 1243, 1106, 1030, 932, 859, 811, 761 cmꢁ1; MS (m/z): 427.26
([Mꢁ1]þ) 100%. HRMS (ESI) calcd for C22H20ClN2O5 ([MꢁH]þ):
427.1066. Found: 427.1068.
1741, 1679, 1618, 1513, 1480, 1382, 1305, 1224, 1114, 1021, 918, 812,
755 cmꢁ1; HRMS (ESI) calcd for C24H25N2O5 ([MꢁH]þ): 421.1769.
Found: 421.1765.
Compound 2i: white solid, 58%, mp 100e101 ꢀC; 1H NMR
Compound 2o: yellow solid, 60%, mp 138e141 ꢀC; 1H NMR
(600 MHz, CDCl3)
d
: 7.40 (d, J¼9.0 Hz, 2H, ArH), 7.31 (t, J¼7.8 Hz, 2H,
(600 MHz, CDCl3)
d
: 8.29 (s, 1H, NH), 7.56 (d, J¼9.0 Hz, 2H, ArH),
ArH), 7.24 (d, J¼9.0 Hz, 2H, ArH), 7.22 (d, J¼7.2 Hz, 1H, ArH), 6.91 (d,
J¼9.0 Hz, 2H, ArH), 5.21 (s, 1H, CH), 4.21e4.09 (m, 2H, CH2),
4.07e4.01 (m, 2H, CH2), 3.80 (s, 3H, CH3), 3.73 (s, 3H, CH3), 2.93 (t,
J¼7.2 Hz, 2H, CH2), 1.09 (t, J¼7.2 Hz, 3H, CH3); 13C NMR (150 MHz,
7.32 (d, J¼9.0 Hz, 2H, ArH), 7.13 (d, J¼9.0 Hz, 2H, ArH), 6.86 (d,
J¼9.0 Hz, 2H, ArH), 5.36 (s,1H, CH), 4.18e4.15 (m,1H, CH), 4.11e4.08
(m, 1H, CH), 3.81 (s, 3H, OCH3), 3.75 (s, 3H, CH3), 1.13 (t, J¼7.2 Hz,
3H, CH3); 13C NMR (150 MHz, CDCl3)
d: 168.3, 164.7, 163.5, 157.7,
CDCl3)
d
: 168.9, 158.0, 138.5, 129.3, 128.9, 128.6, 126.5, 124.5, 114.4,
145.0, 135.3, 131.4, 130.6, 129.2, 125.8, 125.6, 124.2, 122.8, 114.3,
113.7, 113.6, 100.7, 62.1, 61.4, 58.5, 55.4, 51.5, 14.0; IR (KBr) : 3251,
61.6, 55.4, 51.0, 14.0; IR (KBr)
n
: 3454, 3330, 2949, 2838, 2050, 1740,
n

594
H. Gao et al. / Tetrahedron 69 (2013) 589e594
€
6. Wrtz, S.; Rakshit, S.; Neumann, J. J.; Droge, T.; Glorius, F. Angew. Chem., Int. Ed.
2008, 47, 7230e7233.
3056, 2987, 2839, 1699, 1640, 1503, 1449, 1376, 1297, 1220, 1114,
1032, 937, 830, 779 cmꢁ1; MS (m/z): 443.36 ([Mꢁ1]þ) 100%. HRMS
(ESI) calcd for C22H20ClN2O6 ([MꢁH]þ): 443.1015. Found: 443.1015.
7. (a) Bernini, R.; Fabrizi, G.; Sferrazza, A.; Cacchi, S. Angew. Chem., Int. Ed. 2009, 48,
8078e8081; (b) Neumann, J. J.; Suri, M.; Glorius, F. Angew. Chem., Int. Ed. 2010,
49, 7790e7794.
8. (a) Du, Y.; Liu, R.; Linn, G.; Zhao, K. Org. Lett. 2006, 8, 5919e5922; (b) Yu, W.; Du,
Y.; Zhao, K. Org. Lett. 2009, 11, 2417e2420; (c) Liu, W. B.; Jiang, H. F.; Huang, L. B.
Org. Lett. 2010, 12, 312e315.
Acknowledgements
9. Shaabani, A.; Teimouri, M. B.; Arab-Ameri, S. Tetrahedron Lett. 2004, 45,
8409e8413.
10. Nair, V.; Menon, R. S.; Deepthi, A.; Devi, B. R.; Biju, A. T. Tetrahedron Lett. 2005,
46, 1337e1339.
This work was financially supported by the National Natural
Science Foundation of China (Grant No. 21172189) and the Priority
Academic Program Development of Jiangsu Higher Education
Institutions.
11. Yavari, I.; Mokhtarporyani-Sanandaj, A.; Moradi, L.; Mirzaei, A. Tetrahedron
2008, 64, 5221e5225.
12. Kamijo, S.; Kanazawa, C.; Yamamoto, Y. Tetrahedron Lett. 2005, 46, 2563e2566.
13. Yavari, I.; Djahaniani, H. Tetrahedron Lett. 2006, 47, 2953e2956.
14. Asghari, S.; Tajbakhsh, M.; Taghipour, V. Tetrahedron Lett. 2008, 49, 1824e1827.
15. Alizadeh, A.; Rostamnia, S.; Zhu, L. G. Tetrahedron Lett. 2010, 51, 4750e4754.
16. Nakano, H.; Ishibashi, T.; Sawada, T. Tetrahedron Lett. 2003, 44, 4175e4177.
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3401e3404.
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3937e3941.
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1625e1628.
Supplementary data
Crystallographic data 1a (CCDC 875483), 1g (CCDC 875484) and
2d (CCDC 875485) been deposited at the Cambridge Crystallo-
graphic Database Centre. These data can be obtained free of charge
via www.ccdc.ac.ck./data_request/cif. Supplementary data related
to this article can be found online at http://dx.doi.org/10.1016/
j.tet.2012.11.018.
20. Ghabraie, E.; Balalaie, S.; Bararjanian, M.; Bijanzadeh, H. R.; Rominger, F. Tet-
rahedron 2011, 67, 5415e5420.
21. Zhu, Q.; Jiang, H. F.; Li, J.; Liu, S.; Xia, C.; Zhang, M. J. Comb. Chem. 2009, 11,
685e696.
References and notes
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