Catalyst-free, direct, high regio- and chemoselective conversion of epoxides to vicinal haloesters under mild, neutral, and solvent-free conditions

Article abstract of DOI:10.1080/00397911.2011.621097

A catalyst-free, high regio- and chemoselective method is described for the mild conversion of wide varieties of epoxides directly to their corresponding vicinal haloesters using quaternary ammonium halides ^R4N ⁺X^- (X equa

Full text of DOI:10.1080/00397911.2011.621097

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Catalyst-Free, Direct, High Regio- and
Chemoselective Conversion of Epoxides
to Vicinal Haloesters Under Mild,
Neutral, and Solvent-Free Conditions
Ghasem Aghapour a & Razieh Hatefipour a
a School of Chemistry, Damghan University, Damghan, Iran
Accepted author version posted online: 22 Feb 2012.Version of
record first published: 07 Jan 2013.
To cite this article: Ghasem Aghapour & Razieh Hatefipour (2013): Catalyst-Free, Direct, High Regio-
and Chemoselective Conversion of Epoxides to Vicinal Haloesters Under Mild, Neutral, and Solvent-
Free Conditions, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 43:7, 1030-1040
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Synthetic Communications1, 43: 1030–1040, 2013
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2011.621097
CATALYST-FREE, DIRECT, HIGH REGIO- AND
CHEMOSELECTIVE CONVERSION OF EPOXIDES
TO VICINAL HALOESTERS UNDER MILD, NEUTRAL,
AND SOLVENT-FREE CONDITIONS
Ghasem Aghapour and Razieh Hatefipour
School of Chemistry, Damghan University, Damghan, Iran
GRAPHICAL ABSTRACT
Abstract A catalyst-free, high regio- and chemoselective method is described for the mild
conversion of wide varieties of epoxides directly to their corresponding vicinal haloesters
using quaternary ammonium halides R4NþX- (X equals; Cl, Br, I; R ¼ n-butyl, n-pentyl,
n-hexyl) in the presence of an aliphatic or aromatic carboxylic anhydride at room
temperature under neutral and solvent-free conditions.
Keywords Carboxylic anhydride; catalyst-free; epoxide; quaternary ammonium halide;
vicinal haloester
INTRODUCTION
Epoxides are important intermediates in organic synthesis.[1] Their facile regio-
and stereoselective ring-opening reactions with a wide variety of nucleophiles
provide a powerful strategy in organic chemistry.[1–6] However, in most of the
epoxide ring-opening reactions under acidic conditions, the formation of a mixture
of regio-isomers and polymerization is observed. One of the useful nucleophilic reac-
tions of epoxides is their conversion into their vicinal halohydrins,[7] important and
Received July 3, 2011.
Address correspondence to Ghasem Aghapour, School of Chemistry, Damghan University,
Damghan 36715 364, Iran. E-mail: Gh_Aghapour@du.ac.ir
1030

CONVERSION OF EPOXIDES TO VICINAL HALOESTERS
1031
versatile synthons in organic synthesis. Many different reagents or catalysts have
been introduced in various conditions for this purpose.[8,9]
Synthesis of esters has played a most important role in organic synthesis from its
infancy.[10] This importance stemmed from the utility of esters in diverse fields both in
the laboratory and in industry. Ester moieties, irrespective of whether acyclic or cyclic,
constitute major backbones, as well as functional groups of chemical significance, in
numerous natural products and synthetic compounds. Ester groups also play
versatile temporary roles in organic synthesis for protection of carboxylic acids and
hydroxy groups. In this connection, the acetylation of alcohols is one of the most widely
used process for the protection of hydroxy groups, which is routinely carried out by
acid anhydrides or acid chlorides in the presence of tertiary amines,[11] protic or Lewis
acids,[12] or sometimes solid acid catalysts.[13] Many different reagents or catalysts have
also been introduced in various conditions for the esterification reactions.[10]
Although there are several reports concerning the preparation of vicinal halohy-
drins from epoxides using different reagents or catalysts,[8,9] relatively little attention
has been paid to the direct conversion of epoxides into vic-haloesters, although the lat-
ter are superior intermediates in the synthesis of structurally defined bioconjugates[14]
of interest in membranology,[15] enzymology,[16] gene therapy,[17] and drug design.[18]
In addition, these compounds containing two important functional groups (halogen
and ester) have multiple modes of reactivity and represent an interesting and important
subclass. In contrast to simple haloalkanols, which can be conveniently prepared by
cleavage of oxirane derivatives with metal halides under acidic conditions,[4,19] prep-
aration of the corresponding halohydrin esters always poses synthetic problems. The
existing protocols, involving cleavage of the oxirane unit with acyl chlorides (alone[20]
or in combination with CrO2Cl2,[21] CoCl2,[22] a catalytic amount of Bu2SnCl2=
Ph3P,[23] hexaalkylguanidinium chloride,[24] LiClO4 as a catalyst[25]) or related haloacy-
lating system (e.g., TiCl4=EtOAc=imidazole[26]) or with trimethylsilyl halide (TMSX) in
the presence of pyridine and a mixture of carboxylic acid–trifluoroacetic anhydride
(CA-TFAA) under argon at 80ꢀC[27] suffer from certain limitations such as competing
side reactions, performance at high temperature and in acidic media, handling of the
reagent, incompatibility with oxidation- = Lewis acid–sensitive substrates, and perfor-
mance in harmful organic solvents such as CHCl3, CH3CN, or benzene. Another
method based on epoxide ring opening is a SnX2-promoted fission of 2,3-epoxy alcohol
derivatives with TMSX, which after acylation affords O-acetylated vicinal halohydrins
in rather erratic yields and mediocre regioselectivity.[28]
On the other hand, waste prevention and environmental protection are major
requirements in an overcrowded world of increasing demands. Synthetic chemistry
continues to develop various techniques for obtaining better products with less
environmental impact. One of the more promising approaches is solvent-free organic
synthesis.[29] These reactions have many advantages such as reduced pollution, low
costs, and simplicity in process and handling. These factors are especially important
in industry.[30]
Thus, on the basis of these descriptions, the development of simple and efficient
methods for preparation of vicinal haloesters from epoxides especially in neutral and
solvent-free conditions is desirable.
In continuation of our very recent works on the ring opening of epoxides,[31]
especially such as conversion of epoxides to b-chlorohydrins[9d] and also to

1032
G. AGHAPOUR AND R. HATEFIPOUR
2-thiocyanatoalkyl alkanoates,[32] we now report a direct and catalyst-free method
for the conversion of epoxides to vicinal haloesters using quaternary ammonium
halides R4NþX- (X ¼ Cl, Br, I; R ¼ n-butyl, n-pentyl, n-hexyl) in the presence of
an aliphatic or aromatic carboxylic anhydride (R2CO)2O (R2 ¼ CH3, Ph) at room
temperature under neutral and solvent-free conditions (Scheme 1).
First, we took 2,3-epoxypropyl phenyl ether as an example and optimized the
reaction conditions for its conversion to 1-chloro-3-phenoxypropan-2-yl acetate 1
using chloride anion in the presence of acetic anhydride (CH3CO)2O. In this connec-
tion, we found that no desired product 1 was formed using NH4Cl and acetic anhy-
dride in CH3CN or CH2Cl2 as solvent or under solvent-free conditions, at room
temperature or under reflux conditions. Thus, tetrahexylammonium chloride (n-
Hexyl)4NþCl- was used in the presence of acetic anhydride (Ac2O) in various
conditions for this conversion. The results are shown in Table 1. In all of these
catalyst-free reactions, first acetic anhydride was mixed with chloride salt, the reac-
tion mixture was stirred for about 15 min, and then epoxide was added to it.
As shown in this table, this conversion was unsuccessful in the CH2Cl2 or
CH3CN as solvent at room temperature or under reflux conditions. In these cases,
the desired product 1 was obtained in only 0–30% yields using (n-hexyl)4NþCl-=
Ac2O in 1:2 molar ratio after relatively long reaction times (Table 1, entries 6–9).
Under solvent-free conditions, 1 was produced in good yield using (n-hexyl)4
NþCl-= Ac2O in 1.6:1.5 molar ratio at 60 ꢀC after 1 h (Table 1, entry 5) and in poor
yield by 1:0.5 molar ratio of this mixed reagent at room temperature after 22 h
(Table 1, entry 1). The results were better with increasing the amount of acetic anhy-
dride (Table 1, entries 2 and 3). Finally, the best result was obtained in the case of the
entry 4 of this table so that 1 was produced in 95% yield using this mixed reagent
(1:2) at room temperature after 6 h under solvent-free conditions.
We therefore used this conditions (Table 1, entry 4) for the conversion of other
epoxides to their corresponding vicinal haloesters. In this connection, to develop the
applicability of the present method, we exchanged the type of carboxylic anhydride
and also quaternary ammonium halide to benzoic anhydride and tetrabutylammo-
nium bromide or tetrapentylammonium iodide respectively in some cases. However,
these quaternary ammonium halides (1.5 eq.) were used slightly more than tetrahex-
ylammonium chloride for obtaining better results. The results are shown in Table 2.
As shown in this table, epoxides are directly and efficiently converted to vicinal
haloesters in excellent yields by a mixture of R4NþX-=(RCO)2O in 1–1.5:2 molar ratio
at room temperature under mild, neutral, and solvent-free conditions and without a
catalyst. Except for the case of styrene oxide, which produced two regio-isomers
Scheme 1. Direct and catalyst-free conversion of epoxides to vic-haloesters using R4NþX- (X ¼ Cl, Br, I;
R ¼ n-butyl, n-pentyl, n-hexyl) = (R2CO)2O (R2 ¼ CH3, Ph) at room temperature under neutral and
solvent-free conditions. (Figure is provided in color online.)

CONVERSION OF EPOXIDES TO VICINAL HALOESTERS
1033
Table 1. Conversion of 2,3-epoxypropyl phenyl ether to 1-chloro-3-phenoxypropan-2-yl
acetate (1) with a mixture of tetrahexylammonium chloride and acetic anhydride in various
conditions and without using a catalyst
Entry
Solvent
Molar ratioa
Temp. (ꢀC)
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
9
—
—
1:1:0.5
1:1:1
Rt
Rt
22
7
30
75
80
95
60
0
—
—
1:1:1.5
1:1:2
Rt
Rt
6
6
—
1:1.6:1.5
1:1:2
1:1:2
60
Rt
1
CH2Cl2
CH2Cl2
CH3CN
CH3CN
8
Reflux
Rt
Reflux
15
21
21
5
1:1:2
1:1:2
5
30
aMolar ratio is related to epoxide: (n-hexyl)4NþCl-= Ac2O.
(Table 2, entry 6), the reaction of other unsymmetrical epoxides occurred with high
regioselectivity, and the halide anion attacked at the less-hindered side of the epoxide
ring because of the combination of steric and electronic factors.
Under this reaction condition, the ethereal bonds, phenyl ring, carbon–carbon
double bonds, and carbon–halogen bonds as functional groups that are present in
the epoxide molecules remain intact.
To have more insight into the applicability, selectivity, and limitations of the
present method, we studied the possibility of the conversion of 2,3-epoxypropyl phe-
nyl ether to 1 in the presence of some other functional groups in binary mixtures. For
this purpose a binary mixture of 2,3-epoxypropyl phenyl ether and another organic
compound (1:1) was added to a flask containing a stirring mixture of (n-
hexyl)4NþCl-=Ac2O (1:2) at room temperature under solvent-free conditions. The
conversion yields obtained for these selective reactions of different binary mixtures
are shown in Scheme 2. In addition to the various selectivities mentioned, as shown
in this scheme, epoxides can be efficiently converted to their corresponding vicinal
haloesters in the presence of esters, carboxylic acids, aldehydes, amines, and amides
with excellent selectivity using the present method. This excellent chemoselectivity is
probably related to greater reactivity of epoxides compared to these functional
groups in the present reaction medium, which contains both nucleophile (halide
anion) and electrophile (carboxylic anhydride) because of their angle strain.
Although the exact mechanism of this reaction is not clear, it seems that epox-
ide ring concomitantly reacts with both halide anion and carboxylic anhydride from
its less hindered carbon atom and oxygen atom, respectively, converting epoxide to
vicinal haloester directly.
In conclusion, the present investigation has demonstrated that the use of a mix-
ture of quaternary ammonium halides and an aliphatic or aromatic carboxylic anhy-
dride offers a direct, simple, and efficient method, avoiding the use of a catalyst for
the conversion of wide varieties of epoxides to their corresponding vicinal haloesters
in good yields at room temperature under solvent-free conditions. This environmen-
tally friendly method can be efficiently used for preparation of vic-haloesters even in
the presence of many other functional groups with excellent chemoselectivity. Easy

1034
G. AGHAPOUR AND R. HATEFIPOUR
Table 2. Catalyst-free conversion of epoxides to vicinal haloesters using a mixture of R4NþX- (1–1.5 eq.)
(X ¼ Cl, Br, I; R ¼ n-butyl, n-pentyl, n-hexyl) and acetic anhydride or benzoic anhydride (2 eq.) at room
temperature under neutral and solvent-free conditionsa
Entry
Epoxide
vic-Haloesters
Time (h)
Yield (%)b
1
6
95
2
3
4
5
5
6
4
7
92
98
85
97
6
8
79 (19)c, d
7
8
29
7
74
72
9
24
77
aIn all of these reactions, first a mixture of halide salt and carboxylic anhydride was stirred for
15–30 min and then epoxide was added to it.
bIsolated yields.
cYields are based on NMR analysis.
dThe number in parentheses is related to 2-chloro-2-phenylethyl acetate as regioisomeric product.

CONVERSION OF EPOXIDES TO VICINAL HALOESTERS
1035
Scheme 2. Chemoselectivities in the conversion of 2,3-epoxypropyl phenyl ether to
1
using
(n-hexyl)4NþCl-(1 eq.)=Ac2O (2 eq.) at room temperature under solvent-free conditions. (Figure is
provided in color online.)
workup, reduced pollution resulting from lack of using a catalyst and solvent,
availability and ease of handling of reagents, excellent regioselectivity, and operation
under mild and neutral conditions are other advantages of this method.

1036
G. AGHAPOUR AND R. HATEFIPOUR
EXPERIMENTAL
Solvents, reagents, and chemicals were obtained from Merck (Germany) and
Fluka (Switzerland) Chemical Companies. Products are known compounds and were
characterized by their physical or spectral data. Fourier transform–infrared (FT-IR)
spectra were recorded on a Perkin-Elmer RXI spectrophotometer. Nuclear magnetic
resonance spectra were recorded on a Brucker Avance DRX-500 spectrometer.
Thin-layer chromatography (TLC) was carried out on silica-gel 254 analytical sheets
obtained from Fluka.
Typical Procedure for the Conversion of 2,3-Epoxypropyl Phenyl
Ether to 1-Chloro-3-phenoxypropan-2-yl Acetate (1)[25] Using
(n-Hexyl)4NþCl- in the Presence of Acetic Anhydride
Acetic anhydride (2 mmol, 0.189 mL) was added to a flask containing tetrahex-
ylammonium chloride (1 mmol, 0.39 g) at room temperature under solvent-free
conditions. The reaction mixture was stirred until it changed to a homogeneous form
(15 min). Then, 2,3-epoxypropyl phenyl ether (1 mmol, 0.12 mL) was added to the
reaction mixture, and stirring was continued for 6 h so that TLC showed the
completion of the reaction. The crude product was subjected to short column chroma-
tography on silica gel using petroleum bezine as eluent, affording 1, 0.222 g, 95% yield.
1H NMR (CDCl3, 500 MHz): d 2.13 (s, 3H), 3.78–3.82 (dd, 1H, J ¼ 11.67, 5.3 Hz),
3.85–3.88 (dd, 1H, J ¼ 11.68, 5.1 Hz), 4.14–4.20 (m, 2H), 5.32–5.36 (m, 1H),
6.92–7.01 (m, 3H), 7.29–7.32 (m, 2H) ppm; 13C-NMR (CDCl3, 125.77 MHz): d
21.41, 42.96, 66.25, 71.53, 115.01, 121.89, 130.04, 158.60, 170.69 ppm; FT-IR (neat):
3063 (m), 3041 (m), 2961 (s), 2925 (s), 2851 (s), 1747 (s), 1599 (s), 1495 (s), 1222 (s),
1046 (s), 810 (s), 753 (s), 691 (s) cmꢁ1. Mass spectra m=e: 230 (M þ 2, 0.9%), 228
(M, 3%), 137 (M þ 2 – PhO, 22.68%), 135 (M – PhO, 68.83%), 43 (CH3CO, 100%).
Spectral Data
1-Chloro-3-phenoxypropan-2-yl benzoate (5)[25] 1H NMR (CDCl3,
.
500 MHz): d 3.94–4.02 (m, 2H), 4.30–4.37 (m, 2H), 5.58–5.62 (m, 1H), 6.96–7.01
(m, 3H), 7.29–7.33 (m, 2H), 7.45–7.48 (m, 2H), 7.58–7.61 (m, 1H), 8.08–8.10 (m,
2H) ppm; 13C NMR (CDCl3, 125.77 MHz): d 43.14, 66.40, 72.01, 115.17, 121.92,
128.92, 129.94, 130.04, 130.34, 133.88, 158.73, 166.14 ppm; FT-IR (neat): 3063
(w), 3039 (w), 2960 (w), 2882 (w), 1723 (s), 1599 (m), 1588 (m), 1496 (m), 1267 (s),
1242 (s), 1110 (s), 813 (w), 754 (m), 710 (s), 690 (m) cmꢁ1
.
1-Iodo-3-phenoxypropan-2-yl acetate (10). 1H NMR (CDCl3, 500 MHz): d
2.17 (s, 3H), 3.47–3.50 (dd, 1H, J ¼ 10.62, 5.5 Hz), 3.56–3.59 (dd, 1H, J ¼ 10.63,
5.7 Hz), 4.14–4.17 (dd, 1H, J ¼ 10.15, 5.1 Hz), 4.23–4.26 (dd, 1H, J ¼ 10.14, 4.9 Hz),
5.12–5.14 (m, 1H), 6.95–7.04 (m, 3H), 7.33–7.36 (m, 2H) ppm; 13C-NMR (CDCl3,
125.77 MHz): d 3.80, 21.40, 68.42, 71.27, 115.14, 121.89, 130.00, 158.63, 170.49 ppm;
FT-IR (neat): 3062 (w), 3040 (w), 2928 (w), 2876 (w), 1744 (s), 1599 (s), 1588 (m),
1495 (s), 1226 (s), 1172 (m), 1048 (m), 754 (s), 691 (m), 599 (w), 510 (w) cmꢁ1; mass
spectra m=e: 320 (M, 22%), 261 (M – CH3CO2, 1.3%), 227 (M – PhO, 100%), 193
(M – I, 1.47%), 167 (M – PhO – CH3CO2H, 16%), 133 (M – I – CH3CO2H, 44%),

CONVERSION OF EPOXIDES TO VICINAL HALOESTERS
1037
43 (CH3CO, 100%). Anal. calcd. for C11H13IO3 (320.13): C, 41.27; H, 4.09; I, 39.64.
Found: C, 41.23; H, 4.06; I, 39.69.
1-Chloro-3-isopropyloxypropan-2-yl benzoate (3)[25] 1H NMR (CDCl3,
.
500 MHz): d 1.20–1.21 (d, 6H, J ¼ 6.07 Hz), 3.66–3.71 (m, 1H), 3.75–3.79 (m, 2H),
3.86–3.89 (dd, 1H, J ¼ 11.67, 5.24 Hz), 3.92–3.95 (dd, 1H, J ¼ 11.63, 4.59 Hz),
5.36–5.41 (m, 1H), 7.47–7.50 (m, 2H), 7.60–7.63 (m, 1H), 8.10–8.12 (m, 2H) ppm;
13C NMR (CDCl3, 125.77 MHz): d 22.44, 43.68, 66.52, 72.86, 72.94, 128.83,
130.22, 130.25, 133.65, 166.17 ppm.
1-Allyloxy-3-iodopropan-2-yl acetate (8). 1H NMR (CDCl3, 500 MHz): d
2.12 (s, 3H), 3.33–3.37 (dd, 1H, J ¼ 10.47, 5.55 Hz), 3.43–3.47 (dd, 1H, J ¼ 10.46,
5.68 Hz), 3.57–3.60 (dd, 1H, J ¼ 10.42, 5.01 Hz), 3.66–3.69 (dd, 1H, J ¼ 10.42,
4.98 Hz), 4.02–4.05 (m, 2H), 4.90–4.92 (m, 1H), 5.21–5.24 (dd, 1H, J ¼ 10.40,
1.42 Hz), 5.28–5.32 (dd, 1H, J ¼ 17.25, 1.6 Hz), 5.86–5.93 (m, 1H) ppm; 13C NMR
(CDCl3, 125.77 MHz): d 4.36, 21.44, 70.42, 71.79, 72.77, 117.96, 134.59, 170.47 ppm;
FT-IR (neat): 3030 (w), 3013 (w), 2924 (w), 2856 (w), 1747 (s), 1636 (m), 1232 (s),
668 (w), 599 (w), 517 (w) cmꢁ1; mass spectra m=e: 284 (M, 0.3%), 241 (M – CH3CO,
2.9%), 227 (M – C3H5O, 35.2%), 157 (M – I, 100%), 43 (CH3CO, 100%). Anal. calcd.
for C8H13IO3 (284.09): C, 33.82; H, 4.61; I, 44.67. Found: C, 33.89; H, 4.63; I, 44.64.
Trans-1-acetoxy-2-bromocyclohexane (2). Bp ¼ 110–111 ꢀC (12 mm.)
[lit.[33] 109–110 ꢀC (12 mm.)]; FT-IR (neat): 2930 (m), 2862 (m), 1743 (s), 1235 (s),
1038 (m), 696 (w), 602 (w) cmꢁ1
.
Trans-1-benzoyloxy-2-bromocyclohexane (4)[34] 1H NMR (CDCl3,
.
500 MHz): d 1.36–1.39 (m, 1H), 1.47–1.53 (m, 2H), 1.75–1.83 (m, 3H), 2.22–2.32
(m, 2H), 4.01–4.06 (m, 1H), 5.04–5.08 (m, 1H), 7.41–7.45 (m, 2H), 7.53–7.57 (m,
1H), 8.03–8.07 (m, 2H) ppm; 13C NMR (CDCl3, 125.77 MHz): d 23.62, 24.80,
31.00, 35.08, 60.99, 76.77, 128.79, 130.12, 130.70, 133.43, 166.12 ppm; FT-IR (neat):
3069 (w), 3021 (w), 2973 (m), 2930 (w), 2873 (w), 1723 (s), 1602 (w), 1585 (w), 1451
(w), 1270 (s), 1111 (s), 1026 (w), 711 (s), 686 (w) cmꢁ1
2-Chloro-1-phenylethyl acetate (6)[24] 1H NMR (CDCl3, 500 MHz): d 2.14
.
.
(s, 3H), 3.71–3.74 (dd, 1H, J ¼ 11.66, 4.5 Hz), 3.77–3.81 (dd, 1H, J ¼ 11.66, 8.05 Hz),
5.95–5.98 (dd, 1H, J ¼ 8.06, 4.5 Hz), 7.33–7.42 (m, 5H) ppm; 13C-NMR (CDCl3,
125.77 MHz): d 21.40, 46.93, 75.51, 127.09, 129.17, 129.25, 137.64, 170.30 ppm.
2-Chloro-2-phenylethyl acetate (7)[25] 1H NMR (CDCl3, 500 MHz): d 2.06
.
(s, 3H), 4.41–4.44 (dd, 1H, J ¼ 11.74, 5.93 Hz), 4.45–4.49 (dd, 1H, J ¼ 11.74, 7.81 Hz),
5.06–5.09 (dd, 1H, J ¼ 7.71, 5.96 Hz), 7.33–7.42 (m, 5H) ppm; 13C NMR (CDCl3,
125.77 MHz): d 21.15, 60.05, 68.30, 127.83, 129.23, 129.39, 138.06, 170.88 ppm.
1
1-Bromo-3-chloropropan-2-yl acetate (9)[25]. H NMR (CDCl3,
500 MHz): d 2.16 (s, 3H), 3.62–3.64 (m, 2H), 3.78–3.80 (m, 2H), 5.18–5.20 (m, 1H)
ppm; 13C-NMR (CDCl3, 125.77 MHz): d 21.21, 30.71, 43.74, 71.79, 170.24 ppm;
FT-IR (neat): 2962 (m), 2924 (m), 1748 (s), 1373 (m), 1228 (s), 1032 (m), 745 (w),
602 (w) cmꢁ1; mass spectra m=e: 181 (M þ 4 – 37Cl or M þ 2 – 35Cl, 1.5%), 179
(M þ 2 – 37Cl or M – 35Cl, 1.5%), 167 (M þ 4 – CH237Cl or M þ 2 – CH235Cl, 87%),
165 (M þ 2 – CH237Cl or M – CH235Cl, 82%), 158 (M þ 4 – CH3CO2H, 12%), 156

1038
G. AGHAPOUR AND R. HATEFIPOUR
(M þ 2 – CH3CO2H, 51%), 154 (M – CH3CO2H, 38%), 137 (M þ 4 – 81Br or M þ 2 –
79Br, 4.5%), 135 (M þ 2 – 81Br or M – 79Br, 15%), 123 (M þ 4 – CH281Br or M þ 2 –
CH279Br, 17.9%), 121 (M þ 2 – CH281Br or M – CH279Br, 55.2%), 77 (M þ 4 –
CH3CO2H – 81Br or M þ 2 – CH3CO2H – 79Br, 32.8%), 75 (M þ 2 – CH3CO2H –
81Br or M – CH3CO2H – 79Br, 98.6%), 43 (CH3CO, 100%).
ACKNOWLEDGMENTS
We gratefully acknowledge the support of this work by the Damghan
University Research Council.
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