An efficient procedure for the synthesis of phenacyl and benzyl azolium salts using fluorous alcohols

Article abstract of DOI:10.1007/s13738-013-0387-1

An efficient procedure for the synthesis of phenacyl and benzyl azolium salts in 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoroisopropanol as fluorous alcohols have been developed. This synthetic methodology has some advantages with the respect to yield, atom efficiency, solvent and reagents used and wastes generated when compared to the currently in use methods. Using this procedure, a range of phenacyl and benzyl azolium salts can be synthesized with good to excellent yields. The pure salts are separated from the reaction mixture by simple filtration and washing with dry ether.

Full text of DOI:10.1007/s13738-013-0387-1

J IRAN CHEM SOC (2014) 11:1189–1196
DOI 10.1007/s13738-013-0387-1
ORIGINAL PAPER
An efficient procedure for the synthesis of phenacyl and benzyl
azolium salts using fluorous alcohols
•
Ali Khalafi-Nezhad Farhad Panahi
•
•
•
Reza Yousefi Yasaman Gholamalipour
Sina Sarrafi
Received: 18 May 2013 / Accepted: 24 November 2013 / Published online: 6 December 2013
Ó Iranian Chemical Society 2013
Abstract An efficient procedure for the synthesis of
phenacyl and benzyl azolium salts in 2,2,2-trifluoroethanol
and 1,1,1,3,3,3-hexafluoroisopropanol as fluorous alcohols
have been developed. This synthetic methodology has
some advantages with the respect to yield, atom efficiency,
solvent and reagents used and wastes generated when
compared to the currently in use methods. Using this pro-
cedure, a range of phenacyl and benzyl azolium salts can
be synthesized with good to excellent yields. The pure salts
are separated from the reaction mixture by simple filtration
and washing with dry ether.
surfactant, catalyst and plant growth-retardant agent [6, 7].
For cationic polymerization of epoxides, benzyl phospho-
nium salts have been used and in this method benzyl cation
acts as initiator [8]. The presence of a benzyl group in non-
aromatic onium cations increases the physicochemical
properties of the related salts. Consequently, new class of
ionic liquids (ILs), based on quaternary ammonium cat-
ions, containing a benzyl group have been prepared and
used for special applications such as sodium battery elec-
trolytes [9–12]. Moreover, benzyl sulfonium and N-ben-
zylpyrimidinium salts are also used in organic
transformations, particularly for the synthesis of hetero-
cyclic compounds by debenzylation of related salts [13–
16]. On the other hand, phenacyl onium salts deserve
special attention, since they have shown widespread
applications in organic and medicinal chemistry. They are
widely used as photoinitiators for both radical and cationic
polymerizations, because phenacyl onium salts upon irra-
diation forms the phenacylium cation or radical via a het-
erolytic/homolytic cleavage of the C–N bond [17–20]. In
fact, one of the most important applications of phenacyl
compounds (especially salts) is their photochemical reac-
tions [21–28]. Phenacyl onium salts have been used as
protecting groups; for example, one of the newer and more
promising photoremovable protecting groups is p-hydrox-
yphenacyl (pHP), which is widely used in synthesis of
biologically active compounds [29–31]. In addition,
phenacyl ammonium salts are used in medicinal chemistry
for chemotherapy of cancer [32]. The antibacterial and
anticancer activities of some of the phenacyl salts have
been reported [33, 34].
Keywords Fluorous alcohols Á Azolium salts Á
Phenacyl Á Benzyl
Introduction
The aromatic substituents of phenacyl and benzyl frag-
ments have been widely used in organic chemistry for their
special applications [1–5]. The salts of these fragments are
more valuable due to their widespread applications in
organic chemistry. Some of the most important applica-
tions of phenacyl and benzyl based salts are reported here
to show their merit and applicability in organic chemistry.
The benzyl quaternary ammonium salts are used as
A. Khalafi-Nezhad (&) Á F. Panahi Á Y. Gholamalipour Á
S. Sarrafi
Department of Chemistry, College of Sciences,
Shiraz University, 71454 Shiraz, Iran
e-mail: khalafi@chem.susc.ac.ir
On the other hand, the application of phenacyl and
benzyl azolium salts is of widespread interest both indus-
trially and academically. There are many active and diverse
research areas employing these compounds, including
R. Yousefi
Protein Chemistry Laboratory (PCL), Department of Biology,
College of Sciences, Shiraz University, Shiraz, Iran
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Table 1 Optimization of conditions for the reaction of benzothiazole
and phenacyl chloride
Entry
Solventa
Temp (°C)
Time (h)
Yield (%)b
1
THF
Reflux
Reflux
Reflux
Reflux
Reflux
100
12
12
12
12
12
12
12
5
73
2
CH3CN
CHCl3
Toluene
CH2Cl2
DMF
–
79
Fig. 1 The chemical structure of 4, 5-dimethyl-3-(2-oxo-2-phenyl-
ethyl)-thiazolium chloride (ALT-711)
3
67
4
74
5
53
organometallic processes, molecular recognition and bio-
logical research [35]. One of the interesting phenacyl
azolium salts is Alagebrium (ALT-711, 4,5-dimethyl-3-(2-
oxo-2-phenylethyl)-thiazolium chloride). The salt has been
used for breaking of the crosslinks, resulting from forma-
tion of the advanced glycation end products (AGEs) in
diabetes mellitus and aging (Fig. 1) [36–39].
6
65
7
100
78
8
HFIP
TFE
Reflux
Reflux
Reflux
Reflux
Reflux
91 (92)c
89 (90)c
55
9
5
10
11
12
EtOH
iPrOH
H2O
12
12
12
64
Trace
ALT-711 can also reverse the stiffening of blood vessel
walls and accordingly it can be used in hypertension and
cardiovascular diseases. In general, this drug can resolve
many problems associated with sugar-mediated protein
cross-linkings [40]. However, the synthetic methods for the
preparation of azolium salts often suffer from some
drawbacks. The most important limitations associated with
these methods are using toxic solvents, low yields, pro-
longed reaction times and tedious workup process [41–43].
The limitations of the currently used methods are often
originated from the absorbent nature of the organic salts
[44]. Therefore, an approach to improve the efficiency of
these methods is the use of fluorous alcohols as strong
hydrogen donating and solvate water agents, to break away
from the water molecules [45]. Because of high ionizing
power and low nucleophilicity of the fluorinated alcohols,
they have been recognized as a green solvent and catalyst
for application in organic transformations. In current study,
TFE and HFIP were applied as the most commonly used
and commercially available fluorinated alcohols [46–51].
Considering the aforementioned synthetic importance of
benzylium and phenacylium salts, we would like to report
an efficient method for the clean synthesis of phenacyl and
benzyl azolium salts using fluorous alcohols.
Reaction condition: benzothiazole (1 mmol) and phenacyl chloride
(1.1 mmol)
a
Dry solvent (3 mL)
b
Isolated yield
c
The yields in practice are for time of 12 h
As seen in Table 1, conducting the reaction in refluxing
THF, CH3CN, CHCl3, toluene and CH2Cl2 solvents for
12 h, provided the expected product 3a with 73, 79, 67, 74
and 53 isolated yield, respectively (Table 1, entries 1–5).
Performing the reaction in DMF at 100 °C afforded the 3a
only with 65 % isolated yield (Table 1, entry 6). To
improve the reaction yield, we next turned our consider-
ation to the use of solvent-free conditions. In conventional
heating at 100 °C, 75 % of desired product was obtained
after 12 h (Table 1, entry 7). Interestingly, when the
reaction was performed in TFE and HFIP solvents an
elevated yield of product obtained (Table 1, entries 8 and
9). It is notable that, in ethanol and iso-propanol solvents
(non-fluorous alcohols) the yield of product decreased to 55
and 64 %, respectively (Table 1, entries 10 and 11). It
seems that the fluorous alcohols can solvate the substrates
efficiently and also activate the C-X bond by its polariza-
tion through flour atoms to undergo in the reaction [52].
As the reaction was also checked in water as solvent, a
trace amount of product produced (Table 1, entry 12).
After optimization study, we investigated the reaction of
benzothiazole with phenacyl halides and benzyl halides to
find the effect of these substrates on the reaction time and
yield (Table 2).
Results and discussion
Initially, to get phenacyl benzothiazolium salts, we tested
the reaction of benzothiazole (1a) and 2-chloro-1-phenyl-
ethanone (2a) as a simple model substrate in various
reaction conditions. The results of optimization studies are
shown in Table 1.
As shown in Table 2, this protocol is general for both
phenacyl and benzyl halides and the kind of X in the
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J IRAN CHEM SOC (2014) 11:1189–1196
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Since the fluorous solvents are reusable, our convenient
procedure for the synthesis of phenacyl and benzyl azolium
salts may bear relation to clinical significance. This prop-
erty of fluorous solvents and the solubility of substrates in
them gave an improvement to their utilization in synthesis
of azolium salts by facilitating the separation of obtained
salt from the reaction mixture.
Table 2 Reaction of phenacyl and benzyl halides with benzothiazole
under optimized conditions
Entry
Y
X
Time (h)
Yield (%)
Conclusions
1
2
3
4
5
6
COCH2
COCH2
CH2
Cl
5
5
6
5
5
5
91
92
91
93
90
93
Br
In conclusion, we have developed an efficient and clean
method for the synthesis of phenacyl and benzyl azolium
salts using fluorous alcohols. It seems that, the stability of
produced salts and high efficiency of this procedure are
resulted from the hydrogen bond donating and solvate
water abilities of fluorous alcohol. The mild conditions
with excellent yields, short reaction times and the sim-
plicity of product isolation and purifications are significant
advantage of this method.
Cl
CH2
Br
CH2
OTs
OTf
CH2
structure of these substrates have no much effect on the
reaction time and yields. Therefore, fluorous alcohols were
selected for excellent synthesis of benzyl and phenacyl
azolium salts.
Having recognized the best reaction conditions (HFIP or
TFE and reflux), we next tested the generality and limita-
tions of the above system with variants of halide and
nucleobase. The reaction appears quite broad with respect
to the substrates examined, providing the desired salts with
good to excellent yields (Table 3).
Experimental
General
Chemicals were purchased from Acros, Merck, and Aldrich
chemical companies and used without further purification.
Solvents were purified and dried according to the reported
methods and stored over molecular sieves [53]. 1H and 13
As seen in Table 3, all of the products were obtained with
good to excellent yields. It was found that this methodology
works with a broad range of substrates. A series of thiazoles
and different phenacyl and benzyl halides were used in this
protocol. Moreover, the reaction of phenacyl chloride with
2-aryl-benzoxazole and benzothiazoles also proceeded
smoothly with longer reaction time, which is probably due to
their lower reactivity. Using this method ALT-711 as a drug
was obtained in high yield (Table 3, entry 9). 1-Benzyl-1H-
benzimidazole produced 90 % of related salt after 8 h
(Table 3, entry 11). Benzoxazoles also convert to the cor-
responding salts using this procedure after 6 h with 90 %
yield (Table 3, entry 12). The activity of 2-aryl-benzoxazole
is less, and therefore the yield decreased to some extent
(Table 3, entries 13 and 14). When caffeine was reacted with
4-bromophenacyl bromide, a new nucleobase salts obtained
which may possess biological activity for application in
medicinal chemistry (Table 3, entry 15).
C
NMR spectra were recorded on a Bruker Avance 250 MHz
spectrometer in DMSO-d6 and D2O solution with TMS as
an internal standard. FTIR spectroscopy (Shimadzu FT-IR
8300 spectrophotometer) was employed for the character-
ization of the compounds. The microanalyses were per-
formed using a Thermofinnigan Flash EA-1112 CHNSO
rapid elemental analyzer. Melting points were determined
in open capillary tubes in a Barnstead Electrothermal 9100
BZ circulating oil melting point apparatus. The reaction
monitoring was accomplished by TLC on silica gel Poly-
Gram SILG/UV254 plates.
Phenacyl onium and benzylium salts; general procedure
To a mixture of phenacyl/benzyl halide (3.1 mmol) and
HFIP or TFE (3 mL), was added nucleobase (3 mmol). The
resulting mixture was stirred at refluxing temperature of
solvents and based on the times reported in Table 3. The
reaction mixture was cooled to room temperature and
suspended in dry ether (20 mL). The filtrate was washed
with dry ether (20 mL) again and dried in oven under
vacuum for 2 h to obtain pure salt.
Given the large number of commercially available
azoles, nucleobase, phenacyl and benzyl halides, the cur-
rent procedure can be used in synthesis of new categories
of phenacylium and benzylium salts for application in
organic- and medicinal chemistry. This method may find
widespread applications in the filed of organic synthesis
and drug discovery.
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Table 3 The product of
reaction of nucleobases and
phenacyl/benzyl halides in
fluorous alcohols
Entry Nucleobase
Halide
Product
Time
(h)
5
Yield
(%)a
91
S
N
O
S
N
1
Cl
Cl
O
3a
S
N
O
2
5
6
93
91
Br
Cl
S
N
Cl
Br
O
3b
3c
S
N
S
N
3
Cl
Cl
S
S
N
4
5
5
7
92
95
Br
Br
N
O2N
NO2
3d
S
N
S
Br
CH3
O
N
O
H3C
H3C
CH3
Br
3e
S
N
O
S
N
6
3
91
H3C
H3C
Cl
O
Cl
3f
S
N
S
N
7
8
8
5
91
92
Cl
Cl
H3C
3g
S
S
N
Br
Br
N
O2N
H3C
H3C
NO2
3h
H3C
H3C
O
9
5
95
S
N
H3C
H3C
Cl
S
N
Cl
O
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J IRAN CHEM SOC (2014) 11:1189–1196
1193
Table 3 continued
3i
S
O
O
10
5
8
91
90
Cl
S
N
N
H3C
Cl
Cl
H3C
O
3j
11
N
N
Cl
N
N
O
3k
O
O
O
12
6
90
N
N
O
Cl
Cl
3l
O
13
10
89
S
N
N
S
Cl
O
NO2
Cl
NO2
3m
14
10
90
Br
S
O2N
OH
O
N
S
N
Br
OH
NO2
O
3n
Me
O
O
O
O
15
10
90
N
N
N
N
Br
O
Br
N
Br
O
N
N
N
Reaction conditions: nucleobase
(3 mmol), phenacyl/benzyl
halide (3.1 mmol) and HFIP or
TFE (3 mL)
Br
3o
a
Isolated yield
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Experimental data for synthesized salts
d = 62.8, 117.0, 118.5, 121.2, 124.6, 126.5, 129.7, 139.6,
144.7, 156.8. Anal. calcd for C14H11BrN2O2S (351.22): C,
47.88; H, 3.16; N, 7.98; S, 9.13. Found: C, 47.88; H, 3.16;
N, 7.98; S, 9.13.
3-(2-Oxo-2-phenylethyl)-1,3-benzothiazol-3-ium bromide
(3a)
Yield: 91 %; white solid; mp 239–241 °C. IR (KBr):
2,978, 1,682, 1,597, 1,504, 1,450, 1,335, 1,234, 995, 764,
.
687, 594 cm-1 1H NMR (250 MHz, DMSO-d6/TMS):
1-(2-Methoxyphenyl)-methyl-4-methylthiazolium bromide
(3e)
d = 6.77 (s, 2H), 7.18 (dd, J = 6.4, 3.4 Hz, 2H), 7.37–7.42
(m, 1H), 7.63–7.69 (m, 1H), 7.86 (d, J = 3.8 Hz, 1H),
8.08–8.12 (m, 1H), 8.38 (d, J = 9.2 Hz, 1H), 8.55 (d,
J = 9.5 Hz, 1H), 8.78 (s, 1H), 10.64 (s, 1H). 13C NMR
(62.9 MHz, DMSO-d6/TMS): d = 70.3, 117.2, 120.4,
125.0, 126.0, 128.2, 128.3, 128.5, 129.0, 133.6, 134.7,
167.0. Anal. calcd for C15H12ClNOS (289.78): C, 62.17; H,
4.17; N, 4.83; S, 11.07. Found: C, 63.15; H, 4.23; N, 4.99;
S, 11.01.
Yield: 95 %; white solid; mp 190–192 °C. IR (KBr):
3,074, 1,578, 1,493, 1,450, 1,373, 1,346, 1,149, 918, 852,
1
752 cm-1. H NMR (250 MHz, D2O/TMS): d = 2.18 (s,
3H), 2.38 (s, 3H), 4.35 (s, 3H), 5.55 (s, 2H), 6.85 (d,
J = 7.5 Hz, 1H), 7.15–7.21 (m, 2H), 7.24–7.29 (m, 2H),
7.88 (s, 1H), 9.55 (d, J = 2.7 1H). 13C NMR (62.9 MHz,
D2O/TMS): d = 13.3, 43.1, 55.4, 112.8, 116.5, 120.7,
122.1, 125.7, 129.2, 144.5, 156.7, 157.4. Anal. calcd for
C12H14BrNOS (300.21): C, 48.01; H, 4.70; N, 4.67; S,
10.68. Found: C, 48.01; H, 4.70; N, 4.67; S, 10.68.
3-[2-(4-Bromophenyl)-2-oxoethyl]-1,3-benzothiazol-3-ium
chloride (3b)
2-Oxo-2-phenyl–ethyl-4-methylthiazolium chloride (3f)
Yield: 93 %; white solid; mp 251–253 °C. IR (KBr):
Yield: 91 %; white solid; mp 239–241 °C. IR (KBr):
2,974, 1,689, 1,578, 1,446, 1,338, 1,230, 1,169, 995, 918,
822, 748, 687, 606 cm-1. 1H NMR (250 MHz, D2O/TMS):
d = 2.36 (d, J = 1.0 Hz, 3H), 6.20 (t, J = 2.0 Hz, 2H),
7.51–7.57 (m, 3H), 7.67–7.73 (m, 1H), 7.83 (s, 1H),
7.97–8.01 (m, 1H), 9.77 (d, J = 2.7 Hz, 1H). 13C NMR
(62.9 MHz, D2O/TMS): d = 15.1, 61.5, 116.0, 127.3,
132.6, 135.9, 144.8, 156.7, 195.4. Anal. calcd for
C12H12ClNOS (253.75): C, 56.80; H, 4.77; N, 5.52; S,
12.64. Found: C, 56.80; H, 4.77; N, 5.52; S, 12.64.
1
2,981, 1,684, 1,507, 1,463, 1,323, 990, 834, 784 cm-1. H
NMR (250 MHz, D2O/TMS): d = 6.82 (s, 2H), 7.79–7.86
(m, 5H), 8.18 (dd, J = 6.5, 3.3 Hz, 1H), 8.60 (d,
J = 5.5 Hz, 1H), 8.75 (d, J = 8.7 Hz, 1H), 10.81 (s, 1H).
13C NMR (62.9 MHz, D2O/TMS): d = 70.8, 118.1, 119.4,
125.2, 127.3, 129.8, 130.5, 135.0, 140.4, 157.8, 195.4.
Anal. calcd for C15H11BrClNOS (413.13): C, 43.61; H,
2.68; N, 3.39; S, 7.76. Found: C, 43.75; H, 2.72; N, 3.48; S,
7.68.
3-Benzyl-1,3-benzothiazol-3-ium chloride (3c)
1-Phenyl-methyl-4-methylthiazolium chloride (3g)
Yield: 91 %; white solid; mp 190–192 °C. IR (KBr):
2,955, 1,581, 1,497, 1,427, 1,281, 1,211, 1,088, 1,041, 887,
.
771, 732, 694 cm-1 1H NMR (250 MHz, D2O/TMS):
Yield: 91 %; white solid; mp 182–187 °C. IR (KBr):
2,958, 2,861, 1,590, 1,473, 1,312, 1,189, 1,140, 845, 743,
678 cm-1
.
1H NMR (250 MHz, DMSO-d6/TMS):
d = 6.08 (s, 2H), 7.35–7.38 (m, 3H), 7.45–7.50 (m, 2H),
7.34–7.86 (m, 2H), 8.22 (d, J = 8.7 Hz, 1H), 8.44 (dd,
J = 7.2, 2.0 Hz, 1H), 10.72 (s, 1H). 13C NMR (62.9 MHz,
D2O/TMS): d = 62.8, 118.1, 119,0, 124.8, 127.4, 128.3,
129.4, 134.1, 141.5, 156.8. Anal. calcd for C14H12ClNS
(261.77): C, 64.24; H, 4.62; N, 5.35; S, 12.25. Found: C,
64.41; H, 4.75; N, 5.56; S, 12.19.
d = 2.37 (t, J = 2.0 Hz, 3H), 5.52 (t, J = 2.5 Hz, 2H),
7.21–7.25 (m, 2H), 7.34–7.38 (m, 3H), 7. 72 (s, 1H), 9.61
(t, J = 2.75 Hz, 1H). 13C NMR (62.9 MHz, DMSO-d6/
TMS): d = 15.7, 55.6, 118.5, 126.2, 130.3, 135.2, 146.5,
158.4. Anal. calcd for C11H12ClNS (225.74): C, 58.53; H,
5.36; N, 6.20; S, 14.20. Found: C, 58.65; H, 5.42; N, 6.31;
S, 14.11.
1-(4-Nitrophenyl)-methyl-benzothiazolium bromide (3d)
1-(4-Nitrophenyl)-methyl-4-methylthiazolium bromide (3h)
Yield: 92 %; pale yellow solid; mp 210–212 °C. IR (KBr):
2,943, 1,601, 1,492, 1,399, 1,141, 1,105, 734, 690,
Yield: 92 %; yellow solid; mp 228–230 °C. IR (KBr):
2,943, 2,854, 1,605, 1,589, 1,446, 1,346, 1,199, 1,141, 856,
1
595 cm-1. H NMR (250 MHz, D2O/TMS): d = 6.25 (s,
1
744, 698, 598, 482 cm-1. H NMR (250 MHz, DMSOd6/
2H), 6.91 (d, J = 7.5 Hz, 2H), 7.66–7.70 (m, 1H), 8.05 (d,
J = 5.5 Hz, 1H), 8.49 (d, J = 5.6 Hz, 1H), 8.62–8.67 (m,
3H), 10.6 (s, 1H). 13C NMR (62.9 MHz, D2O/TMS):
TMS): d = 2.36 (d, J = 1 Hz, 3H), 5.75 (s, 2H), 7.39 (d,
J = 9.0 Hz, 2H), 7. 81 (s, 1H), 8.14 (dd, J = 7.0, 2.0 Hz,
2H), 9.84 (d, J = 2.7 Hz, 1H). 13C NMR (62.9 MHz,
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J IRAN CHEM SOC (2014) 11:1189–1196
1195
DMSO-d6/TMS): d = 16.1, 58.5, 118.8, 122.4, 131.7,
141.9, 147.0, 158.6. Anal. calcd for C11H11BrN2O2S
(315.19): C, 41.92; H, 3.52; N, 8.89; S, 10.17. Found: C,
41.92; H, 3.52; N, 8.89; S, 10.17.
J = 8.5 Hz, 1H), 8.33 (q, J = 17.0, 9.5 Hz, 2H). 13C NMR
(62.9 MHz, DMSO-d6/TMS): d = 65.9, 119.8, 122.5,
126.3, 128.9, 134.1, 137.3, 141.7, 149.2, 197.8. Anal. calcd
for C21H15ClN2O3S (410.87): C, 61.39; H, 3.68; N, 6.82; S,
7.80. Found: C, 61.56; H, 3.77; N, 6.96; S, 7.71.
2-Oxo-2-phenyl–ethyl-4-methyl-5-vinylthiazolium chloride
(3j)
1-(4-Nitrophenyl)-methyl-2-(3-hydroxy-4-methoxyphenyl)-
benzothiazolium bromide (3n)
Yield: 91 %; brown solid; 68–70 °C. IR (KBr): 2,924,
1
1,697, 1,578, 1,446, 1,230, 995, 922, 760, 686 cm-1. H
Yield: 90 %; cream solid; mp 282–284 °C. IR (KBr):
3,445, 2,862, 1,597, 1,520, 1,447, 1,346, 1,176, 856, 694,
NMR (250 MHz, DMSOd6/TMS): d = 2.26 (s, 3H), 5.17
(d, J = 10.7 Hz, 1H), 5.53 (d, J = 11.0 Hz, 1H), 5.87 (d,
J = 17.2 Hz, 1H), 6.46 (s, 2H), 7.39–7.45 (m, 3H),
7.83–7.97 (m, 2H), 10.18 (s, 1H). 13C NMR (62.9 MHz,
D2O/TMS): d = 8.1, 63.2, 120.9, 129.1, 131.3, 134.0,
137.1, 158.4, 198.1. Anal. calcd for C14H14ClNOS
(279.78): C, 60.10; H, 5.04; N, 5.01; S, 11.46. Found: C,
60.10; H, 5.04; N, 5.01; S, 11.46.
598 cm-1
.
1H NMR (250 MHz, DMSO-d6/TMS):
d = 4.79 (s, 3H), 5.80 (s, 2H), 7.56 (d, J = 8.2 Hz, 2H),
7.70 (d, J = 8.5 Hz, 2H), 7.18 (dd, J = 1.5, 4.1 Hz, 2H),
8.29–8.40 (m, 5H). 13C NMR (62.9 MHz, D2O/TMS):
d = 58.1, 114.5, 116.3, 120.8, 122.0, 126.4, 128.6, 131.3,
141.3, 147.1, 152.6. Anal. calcd for C21H17BrN2O4S
(473.34): C, 53.29; H, 3.62; N, 5.92; S, 6.77. Found: C,
53.48; H, 3.72; N, 6.08; S, 6.63.
1-(2-Oxo-2-phenylethyl)-3-benzyl-benzimidazolium
chloride (3k)
2-Oxo-2-(4-bromophenyl)-ethyl-[1,3,7-trimethyl-1H-
purine-2,6(3H,7H)-dionium] bromide (3o)
Yield: 90 %; cream solid; mp 234–236 °C. IR (KBr):
3,200, 1,730, 1,670, 1,560 cm-1
.
1H NMR (250 MHz,
Yield: 90 %; white solid; mp 235–237 °C. IR (KBr):
3,115, 2,960, 1,715, 1,671, 1,605, 1,362, 1,242, 1,031, 980,
D2O/TMS): d = 5.75 (s, 2H), 6.97 (s, 2H), 7.20–7.32 (m,
5H), 7.65–7.78 (m, 3H), 8.10–8.15 (m, 2H), 8.31–8.42 (m,
4H), 10.41 (s, 1H). 13C NMR (62.9 MHz, D2O/TMS):
d = 58.1, 71.0, 119.3, 126.8, 127.6, 129.4, 129.6, 132.3,
134.1, 137.5, 137.8, 197.2. Anal. calcd for C22H19ClN2O
(362.85): C, 72.82; H, 5.28; N, 7.72. Found: C, 72.93; H,
5.35; N, 7.86.
749, 614, 485 cm-1 1H NMR (250 MHz, DMSO-d6/
.
TMS): d = 3.45 (s, 3H), 3.68 (s, 3H), 3.91 (s, 3H), 6.15 (s,
2H), 7.70 (d, J = 7.5 Hz, 2H), 7.82 (d, J = 8.5 Hz, 2H),
9.25 (s, 1H). 13C NMR (62.9 MHz, DMSO-d6/TMS):
d = 30.3, 31.2, 33.4, 51.2, 122.0, 131.1, 138.2, 141.5,
145.9, 152.1, 155.4. Anal. calcd for C16H16Br2N4O3
(472.13): C, 40.70; H, 3.42; N, 11.87. Found: C, 40.91; H,
3.53; N, 11.98.
2-Oxo-2-phenylethyl-benzoxazolium chloride (3l)
Acknowledgments We would like to thank the financial support of
Iran National Science Foundation (INSF)-Grant no. 88001894, also
the financial supports of Research Councils of Shiraz University are
gratefully acknowledged.
Yield: 90 %; white solid; mp 245–247 °C. IR (KBr):
2,977, 1,686, 1,602, 1,512, 1,441, 1,242, 990, 771, 681,
1
592 cm-1. H NMR (250 MHz, D2O/TMS): 6.85 (s, 2H),
7.55–7.58 (m, 3H), 7.85 (dd, J = 5.0, 1.8 Hz, 1H),
8.08–8.11 (m, 1H), 8.33 (d, J = 6.1 Hz, 2H), 8.40 (d,
5.7 Hz, 1H), 8.50 (d, J = 6.5 Hz, 1H), 10.63 (s, 1H).13C
NMR (62.9 MHz, D2O/TMS): d = 69.5, 117.1, 121.4,
125.3, 125.8, 128.0, 128.1, 128.6, 129.5, 135.1, 193.2.
Anal. calcd for C15H12ClNO2 (273.71): C, 65.82; H, 4.42;
N, 5.12. Found: C, 65.82; H, 4.42; N, 5.12.
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