Simple and efficient method for synthesis of novel 4-substituted 1-acylthiosemicarbazides via one-pot multicomponent reactions

Article abstract of DOI:10.1080/00397910902796110

A new one-pot, multicomponent condensation reaction of aldehydes, 2-naphthol, and 1-acylthiosemicarbazides is described as an efficient method for the synthesis of novel 4-substituted 1-acylthiosemicarbazides in the presence of p-toluenesulfonic acid (p-T

Full text of DOI:10.1080/00397910902796110

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Simple and Efficient
Method for Synthesis of
Novel 4-Substituted 1-
Acylthiosemicarbazides via
One-Pot Multicomponent
Reactions
Naser Foroughifar a , Akbar Mobinikhaledi a & Hassan
Moghanian a
a Department of Chemistry, Faculty of Sciences,
Arak University, Arak, Iran
Version of record first published: 08 Sep 2009
To cite this article: Naser Foroughifar, Akbar Mobinikhaledi & Hassan Moghanian
(2009): Simple and Efficient Method for Synthesis of Novel 4-Substituted 1-
Acylthiosemicarbazides via One-Pot Multicomponent Reactions, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic
Organic Chemistry, 39:20, 3668-3676
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Synthetic Communications1, 39: 3668–3676, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902796110
Simple and Efficient Method for Synthesis
of Novel 4-Substituted 1-Acylthiosemicarbazides
via One-Pot Multicomponent Reactions
Naser Foroughifar, Akbar Mobinikhaledi, and Hassan Moghanian
Department of Chemistry, Faculty of Sciences, Arak University,
Arak, Iran
Abstract: A new one-pot, multicomponent condensation reaction of aldehydes,
2-naphthol, and 1-acylthiosemicarbazides is described as an efficient method
for the synthesis of novel 4-substituted 1-acylthiosemicarbazides in the presence
of p-toluenesulfonic acid (p-TSA) as a catalyst under two conditions: organic
solvent and solvent-free media. The present procedure offers several advantages,
such as good yields, low cost, and very easy workup.
Keywords: Acylthiosemicarbazide, condensation, naphthol, one-pot reaction,
solvent-free
INTRODUCTION
Multicomponent reactions (MCRs) are of increasing importance in
organic and medicinal chemistry.[1–3] The strategies of MCRs offer signi-
ficant advantages over conventional linear-type syntheses for their high
degree of atom economy, convergence, ease of execution, and broad
applications. MCRs are particularly useful to generate diverse chemical
libraries of druglike molecules for biological screening.[4,5] In recent
years, the discovery of novel MCRs has become an increasingly active
Received January 13, 2009.
Address correspondence to Naser Foroughifar, Department of Chemistry,
Faculty of Sciences, Arak University, Arak 38156-879, Iran. E-mail:
n_foroughifar@yahoo.com
3668

4-Substituted 1-Acylthiosemicarbazides
3669
area of research, yielding novel chemical scaffolds for drug discovery.
Thus, the development of new multicomponent reactions is a popular
area of research in current organic chemistry.[6–15]
Acylthiosemicarbazides represent versatile synthons for syntheses of
nitrogen-containing heterocycles. The acylthiosemicarbazide moiety pro-
vides an opportunity to perform cyclocondensations as well as addition–
cyclization reactions. The products of these reactions, triazoles,[16,17]
thiazolidinones,[18] and imidazolidinediones,[19] all possess substantial
pharmaceutical potential.[20–22] Therefore, the synthesis of novel acylthio-
semicarbazide derivatives is interesting for both organic synthesis and
medicinal chemistry.
Recently, we reported the reaction of 2-naphthol and aldehydes (2:1)
in the presence of p-TSA to form dibenzoxanthenes.[23] The reaction pro-
ceeds through the in situ formation of ortho-quinone methides (o-QMs),
and 2-naphthol acted as a nucleophile. To expand this type of tandem
process to permit the condensation of the in situ–generated o-QMs with
nucleophiles other than phenols, we utilized urea, amides, and semicarba-
zide hydrochloride (to work as nucleophiles) to produce amidoalkyl
naphthols[24] and 4-semicarbazonoalkyl-2-naphthols.[25]
With the aim of developing a more efficient synthetic process, we
herein describe a practical and inexpensive method for the synthesis of
novel 4-substituted 1-acylthiosemicarbazides 4, employing a three-
component, one-pot condensation reaction of 2-naphthol 1, aldehydes
2, and acylthiosemicarbazides 3 in the presence of p-tolunesulfonic acid
(p-TSA) as a catalyst in solution and solvent-free conditions (Fig. 1).
1-Acylthiosemicarbazides 3 were prepared from acyl chloride and
thiosemicarbazide according to the reported procedure.[26]
In an initial study, to examine the catalytic activity of different
catalysts such as BiCl3, Bi(NO3)3 ꢀ 5H2O, CeCl3 ꢀ 7H2O, ZrCl4, FeCl3,
AlCl3, SnCl2, CuCl2 ꢀ 4H2O, ceric ammonium nitrate (CAN), and
p-TSA in this condensation reaction, benzaldehyde was first reacted with
2-naphthol and benzoylthiosemicarbazide in CH2Cl2 (5 mL) for 18 h at
Figure 1. Synthesis of 4-substituted 1-acylthiosemicarbazides.

3670
N. Foroughifar, A. Mobinikhaledi, and H. Moghanian
room temperature in the presence of the catalyst (0.1 equiv). In the course
of this study, it was found that p-TSA was the most effective catalyst in
terms of yield of the corresponding product (89%); other catalysts formed
the product with yields of 10–41%.
The solvent effect was also examined by reaction of benzaldehyde (1
equiv) and 2-naphthol (1 equiv) with benzoylthiosemicarbazide (1 equiv)
in the presence of p-toluenesulfonic acid (0.1 equiv) in different solvents.
The reaction using CH2Cl2 as a solvent gave the best result (Table 1,
entry 1); hence it was chosen as a solvent for all further reactions.
To evaluate the generality of the process, several examples illus-
trating the present procedure for the synthesis of 4-substituted
1-acylthiosemicarbazides 4 were studied (Table 2, method A). The reac-
tion of the 2-naphthol 1 with various aromatic aldehydes 2 bearing
electron-withdrawing groups (such as nitro, halide), electron-releasing
groups (such as methyl, methoxy), and acylthiosemicarbazides 3 was
carried out in the presence of p-TSA as a catalyst.
In all cases, the corresponding products 4 were obtained in good to
high yields (Table 2, method A). Under the same conditions, aliphatic
aldehydes (such as propionaldehyde or butyraldehyde) and heterocyclic
aldehydes (such as 2-pyridinecarbaldehyde or furfural) were also
examined, and the corresponding products were obtained successfully.
One the other hand, the reactions with acetylthiosemicarbazide were
considered, but the corresponding products were isolated only in trace
amounts.
The reactions were also carried out under solvent-free conditions,
and surprisingly it was found that aldehydes 2 were rapidly (<40 min)
Table 1. Solvent effect on the reaction of benzaldehyde,
2-naphthol, and benzoylthiosemicarbazide catalyzed by p-TSAa
Time
(h)
Yield
(%)b
Entry
Solvent
1
2
3
4
5
6
7
8
CH2Cl2
CHCl3
CH3CN
EtOH
MeOH
THF
1,4-Dioxane
DMF
18
18
18
18
18
18
18
18
89
87
66
71
74
80
82
38
a10 mol%.
bIsolated yields.

4-Substituted 1-Acylthiosemicarbazides
3671
Table 2. Synthesis of 4-substituted 1-acylthiosemicarbazides in the presence of a
catalytic amount of p-TSAa
Method A
Method B
(%)b (min) (%)b
Time Yield Time Yield
(h)
Entry
Aldehyde 1
Benzaldehyde
4-Methylbenzaldehyde
4-Nitrobenzaldehyde
3-Methoxybenzaldehyde
4-Chlorobenzaldehyde
2-Chlorobenzaldehyde
Furfural
2-Pyridinecarbaldehyde
Propionaldehyde
Butyraldehyde
Benzaldehyde
4-Methoxybenzaldehyde 4-NO2 C6H5
Ar 3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
18
15
24
18
12
21
36
36
30
30
15
21
21
15
18
36
30
30
89
92
85
84
87
81
60
65
78
65
88
78
87
83
90
61
71
66
10
8
8
85
87
85
80
81
78
57
55
75
59
82
73
84
80
88
57
66
59
15
10
15
40
30
20
25
6
15
10
10
8
C6H5
4-NO2 C6H5
3-Nitrobenzaldehyde
4-Chlorobenzaldehyde
4-Methyl benzaldehyde
2-Pyridinecarbaldehyde
Propionaldehyde
4-NO2 C6H5
4-NO2 C6H5
4-NO2 C6H5
4-NO2 C6H5
4-NO2 C6H5
4-NO2 C6H5
40
30
30
Butyraldehyde
aMethod A: reactions were carried out with 10 mol% of p-TSA in CH2Cl2 at
room temperature. Method B: reactions were carried out with 5 mol% of
p-TSA under solvent-free conditions at 125ꢁC.
bIsolated yields.
converted to corresponding products 4 when heated at 125ꢁC in the pre-
sence of only 5 mol% of p-TSA (Fig. 1). We examined the reaction using
various aldehydes under solvent-free conditions, and results are summar-
ized in Table 2 (method B).
CONCLUSION
In conclusion, we have developed a highly efficient synthesis of novel
4-substituted 1-acylthiosemicarbazides from aldehydes, 2-naphthol, and
acylthiosemicarbazides in the presence of p-TSA under organic solvent
(method A) and solvent-free conditions (method B). In addition to the effi-
ciency and simplicity provided by method B, this protocol describes a very
fast, green, and low-cost procedure for the synthesis of these products.

3672
N. Foroughifar, A. Mobinikhaledi, and H. Moghanian
EXPERIMENTAL
General
All products were characterized by a comparison of their spectral (IR, 1H
NMR, 13C NMR, and elemental analysis) data. All yields refer to isolated
products. Infrared (IR) spectra were prepared on a galaxy series Fourier
transform (FT)–IR 5000 spectrophotometer using KBr discs. NMR spec-
tra were recorded on a Brucker spectrophotometer (300 MHz) in DMSO
using tetramethylsilane (TMS) as an internal standard. Elemental
analyses were performed on a Vario EL III elemental analyzer.
General Procedure for the Preparation of 4-Substituted
1-Acylthiosemicarbazides (Method A)
A mixture of aldehyde (1 mmol), 2-naphthol (1 mmol), acythiosemicarba-
zide (1 mmol), and p-TSA (0.1 mmol) in CH2Cl2 (5 mL) was stirred at
room temperature for the appropriate time according to Table 2. The
progress of the reaction was monitored by thin-layer chromatography
(TLC). After completion of the reactions, the mixture was filtered, and
the precipitate was washed with H2O (10 mL) and air dried. The crude
products were purified by recrystallization from EtOH or EtOH–H2O.
General Procedure for the Preparation of 4-Substituted
1-Acylthiosemicarbazides (Method B)
p-TSA (0.05 mmol) was added to a mixture of aldehyde (1 mmol),
2-naphthol (1 mmol), and acythiosemicarbazide (1 mmol). The reaction
mixture was stirred magnetically at 125ꢁC for the appropriate time as
shown in Table 2. The reaction progress was followed by TLC. When
the reaction was completed, the mixture was cooled to room temperature,
washed with H2O (10 mL), and air dried. The crude products were
purified by recrystallization from EtOH or EtOH–H2O.
Representative Spectral Data
Table 2, Entry 1
Mp: 193–195ꢁC; IR (KBr): nmax ¼ 3329, 3180, 3068, 2966, 1680, 1629,
1547, 1267, 1143, 1046, 949, 812, 698 cmꢂ1 1H NMR (300 MHz,
;
DMSO-d6): d ¼ 10.67 (s, 1H), 10.23 (s, 1H), 9.82 (s, 1H), 8.81 (s, 1H),

4-Substituted 1-Acylthiosemicarbazides
3673
8.14 (d, J ¼ 7.9 Hz, 1H), 7.92–7.79 (m, 5H), 7.65–7.53 (m, 4H), 7.35 (t,
J ¼ 7.4 Hz, 1H), 7.27–7.15 (m, 6H); 13C NMR (75 MHz, DMSO-d6):
d ¼ 181.5, 167.0, 153.6, 142.5, 132.8, 132.7, 132.6, 129.9, 129.1, 128.6,
128.5, 128.0, 127.7, 127.6, 126.9, 126.3, 123.3, 122.5, 118.9, 118.8, 53.7.
Anal. calcd. for C25H21N3O2S: C, 70.24; H, 4.95; N, 9.83; S, 7.50. Found:
C, 70.08; H, 5.02; N, 9.72; S, 7.58.
Table 2, Entry 4
Mp: 185–187ꢁC; IR (KBr): nmax ¼ 3347, 3063, 2963, 1667, 1627, 1532,
1
1263, 1163, 1045, 954, 814, 693 cmꢂ1; H NMR (300 MHz, DMSO-d6):
d ¼ 10.68 (s, 1H), 10.26 (s, 1H), 9.81 (s, 1H), 8.75 (s, 1H), 8.09 (d,
J ¼ 7.5 Hz, 1H), 7.92–7.79 (m, 5H), 7.67–7.50 (m, 4H), 7.35 (t, J ¼ 7.6 Hz,
Hz, 1H), 7.18–7.08 (m, 2H), 6.80–6.70 (m, 2H), 6.62 (d, J ¼ 7.2 Hz, 1H),
3.67 (s, 3H); 13C NMR (75 MHz, DMSO-d6): d ¼ 181.4, 167.2, 159.6,
153.5, 144.2, 132.8, 132.7, 132.0, 129.9, 129.6, 129.1, 128.5, 128.0,
127.6, 123.3, 122.5, 121.8, 118.9, 118.8, 118.6, 112.5, 111.7, 55.3, 53.6.
Anal. calcd. for C26H23N3O3S: C, 68.25; H, 5.07; N, 9.18; S, 7.01. Found:
C, 68.05; H, 5.13; N, 9.20; S, 7.16.
Table 2, Entry 6
Mp: 196–197ꢁC; IR (KBr): nmax ¼ 3360, 3304, 3209, 3063, 1651, 1625,
1516, 1294, 1145, 1066, 952, 812, 706 cmꢂ1 1H NMR (300 MHz,
;
DMSO-d6): d ¼ 10.71 (s, 1H), 10.33 (s, 1H), 9.90 (s, 1H), 8.77 (s, 1H),
8.11 (d, J ¼ 7.6 Hz, 1H), 7.92–7.80 (m, 5H), 7.63–7.44 (m, 6H), 7.37 (t,
J ¼ 7.4 Hz, 1H), 7.18 (d, J ¼ 8.5 Hz, 1H), 7.10 (d, J ¼ 8.4 Hz, 2H); 13C
NMR (75 MHz, DMSO-d6): d ¼ 181.6, 166.9, 153.6, 142.0, 132.7, 132.6,
132.4, 131.4, 130.2, 129.2, 128.8, 128.6, 128.5, 128.0, 127.8, 123.4,
122.4, 122.3, 120.1, 120.0, 118.9, 118.3, 53.3. Anal. calcd. for
C25H20ClN3O2S: C, 65.00; H, 4.36; N, 9.10; S, 6.94. Found: C, 64.82;
H, 4.30; N, 9.01; S, 7.05.
Table 2, Entry 9
Mp: 171–172ꢁC; IR (KBr): nmax ¼ 3327, 3190, 2963, 2872, 1670, 1630,
1
1549, 1481, 1265, 945, 808, 692 cmꢂ1; H NMR (300 MHz, DMSO-d6):
d ¼ 10.56 (s, 1H), 10.23 (s, 1H), 9.50 (s, 1H), 8.45 (s, 1H), 8.11 (d,
J ¼ 8.5 Hz, 1H), 7.89 (d, J ¼ 7.2 Hz, 2H), 7.80 (d, J ¼ 8.1 Hz, 1H), 7.72
(d, J ¼ 8.9 Hz, 1H), 7.63–7.48 (m, 4H), 7.30 (t, J ¼ 7.4 Hz, 1H), 7.17 (d,
J ¼ 8.8 Hz, 1H), 6.48 (t, J ¼ 8.3 Hz, 1H), 1.95–1.92 (m, 2H), 0.82 (t,

3674
N. Foroughifar, A. Mobinikhaledi, and H. Moghanian
J ¼ 7.4 Hz, 3H); 13C NMR (75 MHz, DMSO-d6): d ¼ 181.2, 166.8, 153.4,
137.4, 132.7, 132.6, 129.2, 129.1, 128.9, 128.5, 128.0, 127.0, 123.1, 122.8,
119.0, 118.8, 53.0, 27.9, 11.4. Anal. calcd. for C21H21N3O2S: C, 66.47; H,
5.58; N, 11.07; S, 8.45. Found: C, 66.24; H, 5.66; N, 10.96; S, 8.69.
Table 2, Entry 11
Mp: 215–217ꢁC; IR (KBr): nmax ¼ 3462, 3346, 3182, 3065, 2978, 1676,
1
1602, 1524, 1346, 1242, 1060, 947, 851, 696 cmꢂ1; H NMR (300 MHz,
DMSO-d6): d ¼ 11.06 (s, 1H), 10.28 (s, 1H), 9.89 (s, 1H), 8.85 (s, 1H),
8.39 (d, J ¼ 8.7 Hz, 2H), 8.12 (d, J ¼ 8.8 Hz, 3H), 7.89–7.80 (m, 3H),
7.56 (t, J ¼ 7.2 Hz, 1H), 7.35 (t, J ¼ 7.5 Hz, 1H), 7.27–7.16 (m, 6H); 13C
NMR (75 MHz, DMSO-d6): d ¼ 181.5, 165.4, 153.5, 150.1, 142.4, 138.0,
132.8, 130.0, 129.6, 129.2, 128.6, 128.5, 127.7, 127.0, 126.3, 124.4, 123.4,
122.5, 118.9, 118.7, 53.9. Anal. calcd. for C25H20N4O4S: C, 63.55; H,
4.27; N, 11.86; S, 6.79. Found: C, 63.37; H, 4.35; N, 11.77; S, 6.90.
Table 2, Entry 15
Mp: 204–205ꢁC; IR (KBr): nmax ¼ 3433, 3343, 3207, 3067, 2964, 1676,
1
1604, 1530, 1346, 1257, 1063, 949, 826, 715 cmꢂ1; H NMR (300 MHz,
DMSO-d6): d ¼ 11.06 (s, 1H), 10.25 (s, 1H), 9.90 (s, 1H), 8.87 (s, 1H),
8.39 (d, J ¼ 8.6 Hz, 2H), 8.13 (d, J ¼ 8.6 Hz, 3H), 7.87–7.82 (m, 3H),
7.54 (t, J ¼ 7.3 Hz, 1H), 7.35 (t, J ¼ 7.4 Hz, 1H), 7.17–7.03 (m, 5H),
2.22 (s, 3H); 13C NMR (75 MHz, DMSO-d6): d ¼ 181.3, 165.4, 153.5,
150.0, 139.4, 138.2, 136.1, 132.8, 129.9, 129.5, 129.1, 128.6, 127.6,
126.3, 124.3, 123.3, 122.5, 118.8, 116.6, 116.4, 53.8, 21.0. Anal. calcd.
for C26H22N4O4S: C, 64.18; H, 4.56; N, 11.52; S, 6.59. Found: C,
64.11; H, 4.63; N, 11.59; S, 6.68.
ACKNOWLEDGMENT
We gratefully acknowledge the financial support from the Research
Council of Arak University.
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