Journal of the Iranian Chemical Society
1
in DMSO-d , respectively. All reactions were monitored by
H NMR (300 MHz, DMSO-d ) δ 7.19–7.28 (m, 1H),
6
6
TLC on silica gel plates (Fluka Kieselgel 60 F254).
7.35–7.45 (m, 4H), 7.53–7.66 (m, 2H), 7.78–8.18 (m,
1
3
1
H), 12.99 (s, 1H, NH). C NMR (75 MHz, DMSO-d )
6
Preparation of catalysts
δ 150.6, 131.2, 129.5, 129.4, 129.3, 128.8, 128.6, 123.3,
1
22.3, 119.4, 111.9.
The NH (CH ) NH BiCl single crystal has been synthe-
2-(p-Tolyl)-1H-benzimidazole (3c): white solid, yield:
3
2 7
3
5
1
sised by slow evaporation, at room temperature, of aqueous
solutions containing stoichiometric amounts of 1,7-diamino-
heptane NH (CH ) NH (acidified with HCl in large excess)
91%; m.p > 266 °C (Lit. [22] 275–276 °C). H NMR
(300 MHz, DMSO-d ) δ 2.35 (s. 3H. CH ), 7.15–7.26 (m,
6
3
1H), 7.30–7.40 (m, 4H), 7.50–7.60 (m, 2H), 7.70–8.06 (m,
2
2 7
2
1
3
and Bismuth(III) oxide Bi O [30]. The method of synthesis
1H), 12.80 (s, 1H, NH). C NMR (75 MHz, DMSO-d )
2
3
6
consists of dissolving primarily the solid 1,7-diaminohep-
tane (98%) in the necessary HCl solution, dissolving the
Bi O (percentage 99.5%) in HCl solution, and then mixing
δ 151.9, 135.1, 129.9, 129.8, 129.5, 127.9, 122.8, 122.0,
119.1, 111.6, 21.4.
2-(4-Nitrophenyl)-1H-benzimidazole (3d): yellow solid,
2
3
1
the obtained two solutions. The stoichiometric amounts of
NH (CH ) NH and Bi O are (2:1). The mixture solution
yield: 95%; m.p>266 °C (Lit. [22] 318–320 °C). H NMR
(300 MHz, DMSO-d ): δ 6.52–7.00 (m, 1H), 7.15–7.35 (m,
2
2 7
2
2
3
6
was taken under temperature ambient for evaporation; after
few days, the colorless single crystals suitable to X-ray struc-
ture determination were obtained [30].
4H), 7.40–7.67 (m, 2H), 7.82–8.20 (m, 1H), 8.81 (s, 1H,
1
3
NH). C NMR (75 MHz DMSO-d ): δ 153.9, 142.8, 134.4,
6
129.9, 129.3, 127.9, 124.3, 117.5, 116.5.
The NH (CH ) NH BiCl and NH (CH ) NH BiCl
5
2-Phenyl benzothiazole (4a): grey solid, yield: 90%; m.p
3
2 6
3
5
3
2 5
3
1
single crystals have been synthesised by the same method
11–113 °C (Lit. [22] 110–114 °C). H NMR (300 MHz,
1
3
used for the synthesis of NH (CH ) NH BiCl , i.e. by slow
DMSO-d ): δ 6.48–6.58 (m, 6H), 6.83–7.02 (m, 3H).
C
3
2 7
3
5
6
evaporation, at room temperature, of aqueous solutions
containing stoichiometric amounts of 1,6-diaminohexane
NH (CH ) NH (or 1,5-diaminoheptane NH (CH ) NH )
NMR (300 MHz, DMSO-d ): δ 167.8, 145.0, 134.9, 138.3,
6
126.0, 123.4, 122.8, 114.0
2-(4-chlorophenyl) benzothiazole (4b): yellow solid,
2
2 6
2
2
2 5
2
1
and bismuth(III) oxide Bi O [31, 32].
yield: 88%; m.p 114 116 °C (Lit. [22] 114–116 °C). H
2
3
NMR (300 MHz, DMSO-d ) δ 7.29:7.47 (m, 1H), 7.54–7.66
6
1
3
Typical experimental procedure for the synthesis
of heterocycles catalyzed by NH (CH ) NH BiCl
(m, 2H), 7.96–8.11 (m, 4H). C NMR (75 MHz, DMSO-
d ) δ 166.4, 153.9, 136.5, 132.1, 129.9, 128.7, 127.3, 126.2,
3
2 5
3
5
6
1
23.4, 122.9
A mixture of an aldehyde (1 mmol), O-phenylenediamine
1 mmol), O-amino thiophenol or O-amino phenol (1 mmol)
and NH (CH ) NH BiCl (1 mol% is equiv to 5.18 mg) was
2-(p-Tolyl) benzothiazole (4c): white solid, yield: 91%;
1
(
m.p 85–87 °C (Lit. [33] 86–89 °C). H NMR (300 MHz,
DMSO-d ) δ 2.33 (s, 3H), 7.30 (d, 2H, J 7.8 Hz), 7.37 (t,
3
2 5
3
5
6
stirred, in solvent-free conditions, at room temperature for
the appropriate time (Table 3). The progress of the reac-
tion was monitored by TLC hexane/ethyl acetate (70:30)
as eluent. After completion of the reaction (monitored by
thin-layer chromatography), the crude reaction mixture was
dissolved in EtOH, and the catalyst was separated out by
simple filtration. The product was recrystallized from etha-
nol to give, respectively, benzimidazole 3, benzothiazole 4
and benzoxazole 5 in high yields (88–97%, Table 3). Prod-
1H, J=7.2, 7.8 Hz), 7.48 (t, 1H, J=7.2, 7.8 Hz), 7.90 (d, 1H,
J=7.8 Hz), 7.99 (d, 2H, J=7.2 Hz), 8.06 (1H, J=8.4 Hz).
13
C NMR (75 MHz, DMSO-d ) δ 167.8, 154.1, 141.9, 134.8,
6
130.7, 130.3, 127.5, 126.3, 125.8, 123.1, 122.7, 121.6, 21.4.
2-(4-Nitrophenyl) benzothiazole (4d): yellow solid, yield:
1
94%; m.p 226–227 °C (Lit. [22] 227–229 °C). H NMR
(300 MHz, DMSO-d ): δ 6.56–7.35 (m, 4H), 7.74–8.21 (m,
6
1
3
4H). C NMR (75 MHz, DMSO-d ): δ 159.4, 149.7, 141.7,
6
132.2, 130.3, 128.8, 127.6, 126.8, 124.9, 123.9, 121.9.
1
13
ucts were identified by comparison of their H and C NMR
spectra and melting points with those of authentic samples
2-Phenyl benzoxazole (5a): brown solid, yield: 93%; m.p
1
100–102 °C (Lit. [33] 100–102 °C). H NMR (300 MHz,
[
22, 33]. Spectroscopic data for synthesised products are
DMSO-d ): δ 6.92:7.29 (m, 2H), 7.44–7.45 (m, 3H),
6
listed as follows:
7.53–7.54 (m, 1H), 7.58–7.59 (m, 1H), 8.08–8.09 (m, 2H).
1
3
2
-Phenyl-1H-benzimidazole (3a): brown solid, yield:
C NMR (75 MHz, DMSO-d ): δ 159.8, 151.6, 140.4,
6
1
9
0%; m.p > 266 °C (Lit. [22] 292–294 °C). H NMR
131.8, 128.9, 127.8, 125.3, 124.8, 119.6, 114.4.
(
300 MHz, DMSO-d ): δ 7.17–7.25 (m, 2H), 7.46–7.53
2-(4-Chlorophenyl) benzoxazole (5b): yellow solid, yield:
6
1
(
m, 3H), 7.59–7.60 (m, 2H), 8.07–8.18 (m, 2H), 12.93 (s,
91%; m.p 144–145 °C (Lit. [33] 144–146 °C). H NMR
1
3
1
1
H, NH). C NMR (300 MHz, DMSO-d ): δ 151.7, 144.3,
(300 MHz, DMSO-d ) δ 7.10:7.37 (m, 2H), 7.45–749 (m,
6
6
35.5, 130.6, 129.4, 126.9, 122.2, 119.3.
2H), 7.51–7.59 (m, 1H), 7.77–7.83 (m, 1H), 8.00–820 (m,
1
3
2
-(4-Chlorophenyl)-1H-benzimidazole (3b): yellow
2H). C NMR (75 MHz, DMSO-d ) δ 158.3, 151.8, 142.0,
6
solid, yield: 90%; m.p > 266 °C (Lit. [22] 288–290 °C).
137.9, 129.2, 128.1, 125.8, 124.8, 119.5, 113.9.
1
3