Cuso4 - 5h2o: A novel, green, reusable, and environmentally friendly catalyst for the one-pot, four-component synthesis of β-acetamido carbonyl compounds

Article abstract of DOI:10.1080/00397911.2010.529354

Multicomponent reactions for the synthesis of β-acetamido carbonyl compounds have been gained considerable attention in organic synthesis. In this articles, aromatic aldehydes have been employed in a one-pot reaction with enolizable ketones, acetonitrile,

Full text of DOI:10.1080/00397911.2010.529354

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CuSO4 · 5H2O: A Novel, Green, Reusable,
and Environmentally Friendly Catalyst
for the One-Pot, Four-Component
Synthesis of β-Acetamido Carbonyl
Compounds
Farahnaz K. Behbahani a , Neda Doragi a & Majid M. Heravi b
a Department of Chemistry, Karaj Branch, Islamic Azad University,
Karaj, Iran
b Department of Chemistry, School of Sciences, Alzahra University,
Vanak, Tehran, Iran
Accepted author version posted online: 17 Aug 2011. Version of
record first published: 01 Nov 2011
To cite this article: Farahnaz K. Behbahani, Neda Doragi & Majid M. Heravi (2012): CuSO4 · 5H2O:
A Novel, Green, Reusable, and Environmentally Friendly Catalyst for the One-Pot, Four-Component
Synthesis of β-Acetamido Carbonyl Compounds, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 42:5, 705-713
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Synthetic Communications1, 42: 705–713, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.529354
CuSO4 ꢀ 5H2O: A NOVEL, GREEN, REUSABLE, AND
ENVIRONMENTALLY FRIENDLY CATALYST FOR THE
ONE-POT, FOUR-COMPONENT SYNTHESIS OF
b-ACETAMIDO CARBONYL COMPOUNDS
Farahnaz K. Behbahani,1 Neda Doragi,1 and Majid M. Heravi2
1Department of Chemistry, Karaj Branch, Islamic Azad University,
Karaj, Iran
2Department of Chemistry, School of Sciences, Alzahra University,
Vanak, Tehran, Iran
GRAPHICAL ABSTRACT
Abstract Multicomponent reactions for the synthesis of b-acetamido carbonyl compounds
have been gained considerable attention in organic synthesis. In this articles, aromatic
aldehydes have been employed in a one-pot reaction with enolizable ketones, acetonitrile,
benzonitrile, and acetyl chloride in the presence of copper(II) sulfate petahydrate at
ambient temperature to afford the corresponding b-acetamido ketones in very good yields.
New compounds are reported. The use of readily available copper(II) sulfate petahydrate
as a reusable and recyclable catalyst makes this process quite simple, convenient, and
environmentally friendly.
Keywords b-Acetamido carbonyl compounds; catalyst; CuSO4 ꢀ 5 H2O; MCRs; reusable
INTRODUCTION
Recently, CuSO4 ꢀ 5H2O has been used as a Lewis acid catalyst for various
organic transformations such as tetrahydropyranylation–depyranylation of alcohols
and phenols,[1] protection of alcohols and phenols using hexamethyldisilazane,[2] the
one-pot conversion of tetrahydropyrane (THP) ethers to acetates,[3] the chemoselec-
tive synthesis of 1,1-diacetates from aldehydes,[4] the synthesis of quinoxaline deriva-
tives,[5] the synthesis of b-keto esters,[6] the one-pot synthesis of b-hydroxytriazoles
from epoxides,[7] and the synthesis of 1,2,3-triazoles.[8] It is an inexpensive, available,
Received June 27, 2010.
Address correspondence to Farahnaz K. Behbahani, Department of Chemistry, Karaj Branch,
Islamic Azad University, Karaj, Iran. E-mail: Farahnazkargar@yahoo.com
705

706
F. K. BEHBAHANI, N. DORAGI, AND M. M. HERAVI
Scheme 1. Nicomycine.
and extremely safe reagent in chemical reactions. Nowadays, multicomponent reac-
tions (MCRs) are a promising and vital field of chemistry because of the rapid and
efficient synthesis of complicated molecules without the need to isolation intermedi-
ates. It requires minimum effort, which minimizes the environmental loading and is
acceptable from a ‘‘green chemistry’’ point of view.
The MCRs for the synthesis of b-acetamido carbonyl compounds have gained
considerable attention in organic synthesis. The products, containing of b-acetamido
carbonyl skeletons, are found in a number of biologically or pharmalogically impor-
tant compounds such as nikkomycine and neopolyoxines (Scheme 1).[9–11] Recently
it has been reported that b-acetamido ketones can act as a-glocosidase inhibitors.[12]
The best-known route for the synthesis of these compounds is the Dakin–West
reaction,[13] which involves the condensation of an a-amino acid with acetic
anhydride in the presence of a base via an azalactone intermediate.[14] After that,
a number of catalysts such as CoCl2,[15] montmorillonite K-10 clay,[16] Cu(OTf)2=
Sc(OTf)3,[17] silica-supported sulfuric acid,[18] BiOCl,[19] H3PW12O40,[20] ZrOCl2 ꢀ
8H2O,[21] I2,[22] Amberlyst-15,[23] CeCl3 ꢀ 7H2O,[24] H6P2W18O62,[25] FeCl3 ꢀ 6H2O,[26]
ZnO,[27] K5CoW12O40 ꢀ 3H2O,[28] sulfamic acid (SA),[29] heteropolyacid,[30] sulfated
zirconia,[31] zirconium(IV) chloride,[32] ZnO nanoparticles,[33] Fe(ClO4)3 ꢀ 6H2O,[34]
cerium(IV) sulfate,[35] polyaniline-supported acid catalyst,[36] Zr(HSO4),
Mg(HSO4),[37] and Select Flur[38] have been reported as effective catalysts for the
synthesis of b-acetamido carbonyl compounds. However, these procedures have
drawbacks such as long reaction times,[15] high catalyst loadings,[27] or the necessity
for freshly prepared catalyst.[18,20,25] Therefore, there is a need for a greener and cat-
alytically efficient method, which might work under mild and economically cheaper
conditions. In this communication and in continuing our works in catalytic and
MCRs under ecofriendly and solvent-free conditions,[39–43] we disclose a mild and
Scheme 2. Synthesis of b-acetamido carbonyl compounds using CuSO4 ꢀ 5H2O.

CuSO4 ꢀ 5H2O
707
efficient multicomponent condensation reaction utilizing CuSO4 ꢀ 5H2O as a green,
inexpensive, cost-effective, nontoxic, and commercially catalyst for the synthesis of
b-amido carbonyl compounds in the presence of aromatic aldehyde derivatives;
acetophenone derivatives; benzyl, ethyl, and methyl acetoacetate; acetyl chloride;
acetonitrile; and benzonitrile at room temperature (Scheme 2).
RESULTS AND DISCUSSION
To demonstrate the catalytic nature of CuSO4 ꢀ 5H2O, an experiment was con-
ducted in which the reaction of benzaldehyde, acetophenone, acetyl chloride, and
acetonitrile was studied in the absence of catalyst. The reaction was not completed
even after 24 h. Obviously, the catalyst is an essential component of the reaction.
In three separate reactions, a mixture of 4-chlorobenzaldehyde (2.0 mmol), acet-
ophenone (2.0 mmol), acetyl chloride (3.0 mmol), acetonitrile (3.0 mmol), and differ-
ent amounts of CuSO4 ꢀ 5H2O (5.0, 2.5, 1.0 mol%) were stirred at room temperature
without solvent. The conversion was completed within 4.5 h, and the best result was
obtained using 5.0 mol% of CuSO4 ꢀ 5H2O in 92% yield (Table 1). Thus, entry 4 of
Table 1 was selected, and the reactions were continued under similar conditions.
To prove the generality of the optimized reaction conditions, a variety of alde-
hydes with electron-donating and electron-withdrawing groups on the aromatic ring
and enolizable ketones such as acetophenone, 4-nitroacetophnone, and benzyl, ethyl
and methyl acetoacetate were also subjected to Dakin–West reaction in the presence
of CuSO4 ꢀ 5H2O as catalyst. The results showed that the naturality of groups did not
affect the reaction time and yields (Table 2).
In all cases, complete conversion was observed after an appropriate time and
the products were isolated in very good yields. b-Acetamido ketones were also pre-
pared from b-keto esters by the reaction of aromatic aldehydes, acetonitrile, and
acetyl chloride in the presence of CuSO4 ꢀ 5H2O (Table 2, entries 20–25). In almost
1
all cases, anti products were only monitored by H NMR spectra (Table 2, entries
24 and 25), while most articles reported a mixture of anti and syn compounds as
products.[26] Interestingly, it was also found that the products of entries 24 and 25
had not previously been prepared and so they were new compounds. Physical and
spectral data of the entries 24 and 25 have been put in the experimental section.
Table 1. Optimization of CuSO4 ꢀ 5H2O for the synthesis of b-acetamido-b-
(4-chlorophenyl) propiophenone
Entry
X (mol%)
Time (h)
Yield (%)
1
2
3
4
0
24
12
9
15
75
80
92
1
2.5
5
4.5

708
F. K. BEHBAHANI, N. DORAGI, AND M. M. HERAVI
Table 2. Synthesis of b-acetamido carbonyl compounds was catalyzed using CuSO4 ꢀ 5H2O in the pres-
ence of aldehydes, enolizable ketones and ester, acetyl chloride, benzonitrile, and acetonitrile
Mp (ꢁC)
Entry
R1
R2
R3
R4
Time (h)
Yield (%)
Observed
Reported
1
2
H
H
H
H
H
H
Me
Ph
5.0
6.0
6.0
4.0
8.5
9.0
8.5
6.0
7.0
7.2
5.0
5.5
5.8
4.5
4.5
6.0
6.0
5.0
4.5
3
92.5
93.0
95.0
91.0
94.0
90.0
95.0
88.0
89.0
92.0
94.0
87.0
81.0
90.0
92.0
94.0
90.0
92.0
94.0
82
102–104
151–154
101–102
128–129
148
102–104[27]
153–154[26]
101–103[37]
127–129[29]
148–149[16]
142–144[26]
176–179[37]
84–86[35]
139–140[21]
—
130–131[35]
112–114[44]
83–85[16]
147–149[44]
145–147[35]
180–182[26]
—
3
4-NO2
4-OMe
H
Me
Me
Me
Ph
4
5
4-NO2
4-NO2
4-NO2
4-NO2
3-NO2
3-NO2
3-NO2
4-Me
4-Me
4-Br
6
H
143–145
176–180
110–112
136–139
180–181
130
7
4-NO2
4-OMe
H
Me
Me
Me
Me
Me
Me
Me
Me
Me
Ph
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24a
25a
4-NO2
4-OMe
H
Oil
83–84
4-NO2
H
147–149
144–146
177–180
138–140
183–184
110–112
128–130
130–131
110–112
119–120
134–135
149–151
4-Cl
4-Cl
H
H
2-OMe
2-OMe
4-OMe
H
H
Me
Me
Me
Me
Me
Me
Me
Me
Me
4-NO2
H
—
110–112[21]
128–130[26]
131–133[26]
160–161[15]
120–122[44]
—
Me
Me
Me
Et
4-Cl
4-Br
3
84
83
3
4-Br
3
81
88
H
4-Cl
Ben
Ben
3
3
80
—
aNew compounds.
CuSO4 ꢀ 5H2O was chosen as the catalyst because of its moisture stability, reco-
verability, and reusability without any loss of the catalytic activity. Therefore, this
method provides b-amido carbonyl compounds in simple, efficient, and novel green
protocol directly. The mechanism[17,27] may involve the enolic form of the ketone,
which attacks the activated aldehyde to provide a product 2 after exchange of Hþ
from 1. Next, the nitrile attacks 2 with elimination of acetate to give 3. Hydrolysis
of 3 accompanied by tautomerization gave the desired b-amido ketone 4 (Scheme 3).
To show the merits and advantages of using copper(II) sulfate as a catalyst
in the synthesis of N-(3-oxo-1,3-diphenylpropyl) acetamide, our protocol was com-
pared with previously reported methods (Table 3). From the results given in Table 3,
the advantages of our method are evident regarding the yields of the reactions, which
are very important in the chemical industry especially when it is combined by easy
separation.
CONCLUSION
In conclusion, the present work describes a simple, efficient, and green protocol
for the preparation of b-amido carbonyl compounds using CuSO4 ꢀ 5H2O as a

CuSO4 ꢀ 5H2O
709
Scheme 3. Suggested mechanism for the reaction. (Figure is provided in color online.)
reusable catalyst. The salient features of this procedure include very easy workup,
good yields of the products, avoidance of column chromatography, easy and safe
handling, no toxicity, reusability of the catalyst, and synthesis of some new b-acet-
amido carbonyl compounds.
EXPERIMENTAL
Melting points were measured by using the capillary tube method with an
Electrothermal 9200 apparatus. Infrared (IR) spectra were recorded on a Perkin-
Elmer Fourier transform (FT)–IR spectrometer with scanning between 4000 and
.
400 cmꢂ1 1H NMR and 13C NMR spectra were obtained on a Bruker DRX
400-MHZ NMR instrument. Chemicals shifts are reported in parts per million (S)
relative to tetramethylsilane (S 0.0) as internal standard. Elemental analyses were
performed by elemental analyzer Vario EL. Analytical thin-layer chromatography
(TLC) of all reactions was performed on Merck precoated plates (silica gel
60 F-254 on aluminium). All starting materials purchased from Merck Company
and used without more purification.
Synthesis of b-Acetamido Ketone and Esters: General Procedure
A mixture of ketone or benzyl, ethyl, and ethyl acetoacetate (2.0 mmol), alde-
hyde (2.0 mmol), and acetyl chloride (3.0 mmol) in acetonitrile=benzonitrile
(3.0 mmol) was treated with a catalytic amount of CuSO4 ꢀ 5H2O (5.0 mol%) at room
temperature. The progress of reaction was monitored by TLC. Upon completion of
the reaction, a mixture of crushed ice (50 ml) was added to the reaction mixture. The

710
F. K. BEHBAHANI, N. DORAGI, AND M. M. HERAVI
Table 3. Various of catalysts were used in the one-pot, three-component synthesis of N-(3-oxo-1,3-
diphenylpropyl) acetamide
Catalyst
Amount (mol%)
Time (h)
T (ꢁC)
Yield (%)[Ref]
Montmorilonite K-10
Silica sulfuric acid
Sc(OTf)3
2g
78
10
10
10
10
20
100
100
5
7
1.08
30
30
30
4.5
7
70
80
Rt
Rt
Rt
Rt
Rt
Rt
Rt
Rt
Rt
Rt
Rt
80
Rt
Rt
80
80
80
80
80
Rt
80
Rt
Rt
85
Rt
Rt
Rt
Rt
50
Rt
80[45]
91[18]
82[17]
64[17]
69[17]
85[22]
92[19]
59[26]
19[26]
95[20]
90[21]
96[24]
89[23]
90[28]
90[29]
88[33]
40[27]
65[27]
35[27]
20[27]
90[27]
Cu(OTf)2
Bi(oTf)3
I2
BiCl3 or BiOCl
LiClO4
InCl3
0.5
0.5
0.83
5
H3PW12O40
ZrOCl2 ꢀ 8H2O
CeCl3 ꢀ 7H2O
Amberlyst-15
ZnO
20
10
0.2 g
50
5
7
6
6
NH2SO3H
FeCl3 ꢀ 6H2O
CuO
1.41
8
10
50
50
50
50
50
0.5 g
0.7
10
10
20
20
20
20
20
4.8
5
20
20
18
18
6
Fe2O3
CdO
TiO2
ZnO
Nafion-H
Heteropolyacid
ZnO bulk
ZnO nanoparticles
CeSO4
4
96[46
]
0.41
4
86[25]
55[33]
1
83[33]
3.5
0.83
0.5
5
83[35]
Mg(HSO4)2
Zr(HSO4)2
ZrCl4
89[37]
90[37]
80[37]
MgCl2
PANI-H2SO4
CuSO4 ꢀ 5H2O
20
1
30[37]
90[36]
92 (this work)
5
precipated solid was filtered off. The residue was washed with 20 ml of water, and the
crude product was recrystallized from ethyl acetate=n-hexane.
Recycling of the Catalyst
At the end of reaction, ice water was added to the reaction mixture. The pre-
cipated solid was filtered off. Then liquid mother was evaporated, and the catalyst
was removed, washed with dichloromethane and ethyl acetate, dried at 65 ꢁC for
3 h, and reused in another reaction (three runs). The recycled catalyst was subjected
to three reactions without observation of appreciable loss in its activity.
Physical and Spectral Data for New Compounds
Benzyl 2-(acetamido(phenyl)methyl)-3-oxobutanoate (Table 2, Entry
24). Mp 134–135 ꢁC; white solid IR (KBr): 3368.02 (s), 1736.18 (s), 1715.30 (s),

CuSO4 ꢀ 5H2O
711
1650.52 (s), 1528.70 (s), 1458.03 (m), 1373.60 (s), 1293.46 (s), 1244.49 (m), 1140.59
(s), 1097.10 (s), 705.25 (s) cmꢂ1
.
1H NMR (400 MHz, CDCl3) d ¼ 1.93 (s, 3H,
NHCOCH3), 2.13 (s, 3H, CHCOCH3), 4.12 (d, J ¼ 7.98 Hz, 1H, CHCOCH3), 5.11
(s, 2H, OCH2Ph), 5.78 (dd, J ¼ 11.95 Hz, 1H, CHNHCOCH3), 6.94 (d, J ¼ 11.47 Hz,
Hz, 1H, NH), 7.28 (m, 10H, Ar). 13C NMR (CDCl3, 400 MHz) d 203.2, 170.8, 170.0,
143.5, 141.2, 128.6, 127.2, 68.5, 65.1, 57.9, 28.1, 33.6. Elem. anal. C20H21NO4: C,
70.78; H, 6.24; N, 4.13; O, 18.86.
Benzyl 2-(acetamido(4-chlorophenyl)methyl)-3-oxobutanoate (Table 2,
Entry 25). Mp 149–151 ꢁC; white solid. IR (KBr): 3366.24 (m), 1739.29 (s),
1718.12 (m), 1651.24 (s), 1526.22 (s), 1456.25 (w), 1361.20 (m), 1294.42 (s),
1242.56 (m), 1142.41 (s), 1092.07 (m), 694.34 (s) cmꢂ1. 1H NMR (400 MHz, CDCl3)
d ¼ 1.92 (s, 3H, NHCOCH3), 2.14 (s, 3H, CHCOCH3), 4.08 (d, J ¼ 8.01 Hz, 1H,
CHCOCH3), 5.11 (s, 2H, OCH2Ph), 5.70 (dd, J ¼ 11.97, 1H, CHNHCOCH3), 6.89
(d, J ¼ 11.91 Hz, 1H, NH), 7.36–7.28 (m, 9H, Ar). 13CNMR (CDCl3, 400 MHz) d
203.2, 170.8, 170.0, 141.2, 132.0, 128.4, 127.2, 68.5, 65.1, 57.9, 28.1, 23.6 ppm. Elem.
anal. C20H20ClNO4: C, 64.26; H, 5.39; Cl, 9.48; N, 3.75; O, 17.12.
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