Reactions of 1-aryl-2,2-dihalogenoethanone oximes with tetrasulfur tetranitride (S4N4): A general method for the synthesis of 3-aryl-4-halogeno-1,2,5-thiadiazoles

Article abstract of DOI:10.1039/a704408i

1-Aryl-2,2-dichloro-7, 1-aryl-2,2-dibromo-8, 1-aryl-2-bromo-2-fluoro-9 and 1-aryl-2-chloro-2-fluoroethanone oximes 10 have been prepared by allowing the corresponding ketones to react with hydroxylamine hydrochloride in EtOH at room temperature. Stereoche

Full text of DOI:10.1039/a704408i

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Reactions of 1-aryl-2,2-dihalogenoethanone oximes with tetrasulfur
tetranitride (S4N4): a general method for the synthesis of
3-aryl-4-halogeno-1,2,5-thiadiazoles
Sung Cheol Yoon, Jaeeock Cho and Kyongtae Kim*
Department of Chemistry, Seoul National University, Seoul 151-742, Korea
1-Aryl-2,2-dichloro-7, 1-aryl-2,2-dibromo-8, 1-aryl-2-bromo-2-fluoro-9 and 1-aryl-2-chloro-2-fluoro-
ethanone oximes 10 have been prepared by allowing the corresponding ketones to react with
hydroxylamine hydrochloride in EtOH at room temperature. Stereochemical assignments for the oximes
1
were made on the basis of H NMR spectroscopic evidence and an X-ray crystallographic analysis of
1-(3-chlorophenyl)-2,2-dichloroethanone oxime 7f. The 1-aryl-2,2-dihalogenoethanone oximes react
with tetrasulfur tetranitride in refluxing 1,4-dioxane to give 3-aryl-4-chloro-1, 3-aryl-4-bromo-2, and
3-aryl-4-fluoro-1,2,5-thiadiazoles 3 in 69–98, 49–99, and 32–65% yields, respectively. A mechanism for the
formation of the 1,2,5-thiadiazoles is proposed.
In order to widen the scope of the reaction with α-halogeno
Introduction
ketoximes, the readily available 1-aryl-2,2,2-trifluoromethanone
oximes 5c were treated with S4N4 in refluxing 1,4-dioxane,6 to
give 5-aryl-5-trifluoromethyl-5H-1,3,2,4,6-dithiatriazines 6 as
the major products. Because of this unexpected result together
with the formation of 2 from the reactions of 5b with S4N4, we
have investigated on the reactions of the 1-aryl-2,2-
dihalogenoethanone oximes 7–10 with S4N4 and describe herein
over results.
3-Aryl-4-halogeno-1,2,5-thiadiazoles 1–3 have attracted much
attention since the 3-chloro-, 3-fluoro, 3-aryl-4-chloro, and/or
3-aryl-4-fluoro-derivatives show herbicidal1 or nematicidal
effects.2 The synthesis of 3-chloro- and 3-aryl-4-chloro-1,2,5-
thiadiazoles has been extensively studied by Weinstock and co-
workers3 in a method involving the reaction of sulfur mono-
chloride (S2Cl2) with α-aminoacetonitrile bisulfate, α-amino-
phenylacetonitrile hydrochloride, isonitrosophenylacetonitrile,
or glyoxime in DMF at different reaction temperatures. This
method has been widely utilized for the synthesis of 3-bromo-
and 3-chloro-1,2,5-thiadiazoles. Alternatively, 3-aryl-4-chloro-
1 and 3-aryl-4-bromo-1,2,5-thiadiazoles 2 have been prepared
by reactions of the corresponding 4-hydroxy compounds with
phosphorous oxychloride3 and phosphorus oxybromide,4
respectively, and 3-aryl-4-fluoro-1,2,5-thidiazoles 3 by treating
the corresponding chloro analogues with potassium fluoride at
elevated temperature.2
Recently we reported a facile and much improved synthesis
of 3-aryl-1,2,5-thiadiazoles 4, by allowing 1-aryl-2-chloroeth-
anone oximes 5a to react with S4N4 in refluxing 1,4-dioxane;5
no chlorine-containing 1,2,5-thiadiazoles 1 were detected.
However, treatment of 1-aryl-2-bromoethanone oximes 5b
under the same conditions gave compounds 2 as the minor
and compounds 4 as the major products (Scheme 1).
Results and discussion
Synthesis of compounds 7–9
Although the synthesis and stereochemistry of E- and Z-5a
and 5b have been much studied,7 the 1-aryl-2,2-dihalogeno-
ethanone oximes 7–10 have received little attention, apart from
2,2-dichloro-1-phenylethanone oxime 7a (Ar = Ph) a patent for
which describes its importance as an anti-herbicide.8 Since
attempted synthesis of 7a according to literature procedures
failed, reactions under different conditions were studied,9 and
compounds 7 finally prepared via the 1-aryl-2,2-dichloro-
ethanones 12; the latter were prepared by chlorination of 1-
arylethanones 11 according to a little modified literature pro-
cedures10 in good to moderate yields (Scheme 2). Reaction
X = Cl
7
X2, AcOH
NH2OH•HCl
EtOH, RT
ArC(=O)CHX2
ArC(O)CH3
40-59 o
C
S4N4
8
X = Br
X = Cl, Br
12 X = Cl
13 X = Br
11
1,4-dioxane, heat
Scheme 2
5a
5c
7
9 or 10
5b
8
times, yields, and melting points of compounds 7 are summar-
ized in Table 1.
Of the compounds 12 prepared,10 12i [Ar = 4-Cl2CH-
C(O)C6H4], 12j [Ar = 3-Cl2CHC(O)C6H4], and 12k [4-Cl2-
CHC(O)biphenyl] are new. All of the compounds 7 except for
7a8 are new and their structures were assigned on the basis of
spectroscopic data and elemental analyses.
Ar
CF3
Ar
Ar
Cl Ar
Br Ar
F
N
NH
S
4 + 2
N
N
N
N
N
N
N
N
S
S
S
S
S
N
6
1
2
3
4
1
The H NMR spectra of compounds 7a–b, 7d, 7g, h and 7j
exhibited two singlets at 6.48 and 7.40, 6.45 and 7.30, 6.41 and
7.60, 6.50 and 7.41, 6.48 and 7.37, 6.47 and 7.34 ppm, respect-
ively, which were assigned to be methine proton signals of E-
and Z-oximes in view of the reported chemical shifts of
methylene protons of Z- (4.42 ppm) and E-2-bromo-1-
phenylethanone oximes (4.30 ppm).7 However, compounds 7c,
ArC(=NOH)CXYZ
5a X = Cl, Y = Z = H
5b X = Br, Y = Z = H
5c X = Y = Z = F
7 X = Y = Cl, Z = H
8 X = Y = Br, Z = H
9 X = Br, Y = F, Z = H
10 X = Cl, Y = F, Z = H
Scheme 1
J. Chem. Soc., Perkin Trans. 1, 1998
109

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Table 1 Reaction times, yields, and melting points of 1-aryl-2,2-
dichloroethanone oximes 7
Table 2 Selected bond lengths (Å) for compound 7fa
Cl(1)᎐C(1)
Cl(2)᎐C(8)
Cl(3)᎐C(8)
O᎐N
1.736(3)
1.768(3)
1.787(3)
1.389(3)
N᎐C(7)
C(4)᎐C(7)
C(7)᎐C(8)
1.282(4)
1.481(4)
1.502(4)
Time Yield Mp
(t/h)
Compd. Ar
(%)a (T/ ЊC)
7a
7b
7c
7d
7e
7f
7g
7h
7i
C6H5
24
24
34
47
48
49
27
72
72
72
86
81
73
58
85
82
84
34
82
53
86
Liquidb
Liquidb
112–114c
Liquidb
92–94c
4-MeC6H4
4-O2NC6H4
3-O2NC6H4
4-BrC6H4
4-ClC6H4
4-FC6H4
3-Cl,4-MeOC6H3
4-Cl2CH(HON᎐C)C6H4
3-Cl2CH(HON᎐C)C6H4
4Ј-Cl2CH(HON᎐C)biphenyl-4-yl 72
a Crystallographic numbering scheme, see Fig. 1.
Table 3 Selected bond angles (Њ) for compound 7fa
98–100d
Liquidb
Liquidd
170–172e
Liquidb
133–135e
C(7)᎐N᎐O
113.9(2)
118.7(3)
119.8(2)
121.6(3)
115.8(2)
N᎐C(7)᎐C(8)
121.1(2)
123.1(2)
112.1(2)
110.1(2)
110.1(2)
C(3)᎐C(4)᎐C(5)
C(3)᎐C(4)᎐C(7)
C(5)᎐C(4)᎐C(7)
N᎐C(7)᎐C(4)
C(4)᎐C(7)᎐C(8)
C(7)᎐C(8)᎐Cl(2)
C(7)᎐C(8)᎐Cl(3)
Cl(2)᎐C(8)᎐Cl(3)
᎐
᎐
᎐
7j
7k
a Crystallographic numbering scheme, see Fig. 1.
a Isolated yield. b E/Z mixture. c,d,e CHCl3, CCl4, and EtOH were used as
solvents for recrystallization, respectively.
Table 4 Reaction times, yields, and melting points of 1-aryl-2,2-
dibromoethanone oximes 8
Time Yield Mp
(t/h)
Compd. Ar
(%)a (T/ЊC)
8a
8b
8c
8d
8e
8f
C6H5
48
72
72
48
48
86
48
36
63
96
72
72
61
58
72
75
80
82
84
74
66
61
76
93
80
Liquidb
105–107c
125–127c
Liquidb
100–101c
108–109d
Liquidb
97–99d
4-MeC6H4
4-O2NC6H4
3-O2NC6H4
4-BrC6H4
4-ClC6H4
4-FC6H4
4-MeOC6H4
3-MeOC6H4
C10H8
8g
8h
8i
80–82d
8j
97–98c
8k
8l
4-Br2CH(HON᎐C)C6H4
3-Br2CH(HON᎐C)C6H4
4Ј-Br2CH(HON᎐C)biphenyl-4-yl 72
176–178d
Liquidb
173–175d
᎐
᎐
᎐
8m
Fig. 1 ORTEP drawing of compound 7f
a Isolated yield. b E/Z mixture. c,d CCl4 and EtOH were used as solvents
for recrystallization, respectively.
7e, and 7f exhibited only a singlet at 7.58, 7.50, and 7.42 ppm.
Therefore, they were assigned as Z-oximes. This was con-
firmed by a X-ray single crystallographic analysis of compound
7f for which Fig. 1 shows an ORTEP drawing and Tables 2 and
3, respectively, list selected bond distances and angles.
1-Aryl-2,2-dibromoethanone oximes 8 were prepared from 1-
aryl-2,2-dibromoethanones 13 under the same conditions as for
compounds 7 in good to moderate yields (Scheme 2). Com-
pounds 13 prepared according to the literature procedures11 are
known except for 13g (Ar = 4-FC6H4, X = Br), 13i (Ar = 3-
MeOC6H4, X = Br), 13k [Ar = 4-Br2CHC(O)C6H4, X = Br], 13l
[Ar = 3-Br2CHC(O)C6H4, X = Br], and 13m (Ar = 4-Br2CH-
C(O)biphenyl, X = Br). Reaction times, yields, and melting
points for compounds 8 are summarized in Table 4.
temperatures >50 ЊC, whereas the reaction proceeded very slow-
ly at <40 ЊC. Reaction times and yields of 9, 10, and 15 are
summarized in Table 5.
All of compounds 15 prepared are known, whereas com-
pounds 9 and 10 are new. 1H NMR spectra of 9a and 10 show
two singlets at 6.71 and 7.54 ppm due to the methine protons
for the E- and Z-forms. For compounds 7–10, it has been found
that where they exist as solids they appear to be solely Z-
isomers, whereas products which are oils are mixtures of E- and
Z-geometrical isomers showing a preference for the latter form.
The formation of Z-isomers in preference to E-isomers may be
due to the ease of formation of hydrogen bonding between the
OH group and the halogen atoms of α,α-dihalogeno ketoximes.
For compounds 8a, 8d, 8g, and 8l, the presence of two sing-
lets at 6.59 and 7.44, 6.42 and 7.59, 6.46 and 7.24, and 6.43 and
7.29 ppm, respectively suggested that, as with compounds 7,
each product was a mixture of E- and Z-oximes. Other com-
pounds 8 exhibited a singlet in the range of 7.18–8.16 ppm,
indicating the formation of a single isomer, i.e. Z-oximes.
Similarly, 1-aryl-2-bromo-9 and 2-chloro-2-fluoro-ethanone
oximes 10 were prepared via the corresponding 1-aryl-2-
halogeno-2-fluoroethanones 15 which were, in turn, prepared
by treatment of 1-aryl-2-fluoroethanones 1412 with bromine or
thionyl chloride, respectively, according to literature pro-
cedures13 (Scheme 3). Yields of 15 decreased with reaction
Reactions of 1-aryl-2,2-dihalogenoethanone oximes 7–10 with
S4N4
The reactions of 7 and 8 with S4N4 in refluxing 1,4-dioxane gave
1 and 2, respectively. Compounds 9 and 10 reacted with S4N4
to give 3 under the same reaction conditions. The reactions of 7
and 8 were quenched when no spot corresponding to 7
(RF ≅ 0.09, C6H6) and 8 (RF ≅ 0.20, C6H6) was observed on
TLC, whereas those of 9 (RF ≅ 0.08, C6H6) and 10 (RF ≅ 0.07,
C6H6) were quenched when the spot corresponding to S4N4
(RF = 0.51, C6H6–hexane, 1:1) had disappeared on TLC by the
time the colour of the solution became reddish brown. Reaction
times, yields and melting points of compounds 1–3 are sum-
marized in Tables 6, 8, and 10, respectively, and their analytical
Br2, AcOH
40-50 o
X = Br
1
C
9
IR, and H NMR data are summarized in Tables 7, 9, and 11,
NH2OH•HCl
EtOH, RT
ArC(O)CH2F
ArC(O)CHXF
respectively.
10
X = Cl
S(=O)Cl2
Of the compounds listed in Table 7, compounds 2a and 2f
were reported to be prepared by treating 3-hydroxy-4-phenyl-
and 3-(4-chlorophenyl)-4-hydroxy-1,2,5-thiadiazoles with phos-
phorus oxybromide in 61 and 85% yields,4 respectively.
14
15
X = Br, Cl
Scheme 3
110
J. Chem. Soc., Perkin Trans. 1, 1998

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Table 5 Reaction times, yields, and melting points of 1-aryl-2-bromo-9 and 2-chloro-2-fluoro-ethanone oximes 10, and 1-aryl-2-halogeno-2-
fluoroethanones 15
Compound Ar
X
Time (t/h)
Yield (%)a
Compound Time (t/h)
Yield (%)a
Mp (T/ЊC)
15a
15b
15c
15d
C6H5
Br
Br
Br
Cl
7
5
9
78
73
71
49
9a
9b
9c
48
48
3
84
91
89
71
Liquidb
94–96c
4-MeC6H4
4-BrC6H4
C6H5
101–103c
Liquidb
15
10
24
a Isolated yield. b E/Z mixture. c CHCl3 was used as a solvent for recrystallization.
Table 6 Reaction times, yields, and melting points of 3-aryl-4-chloro-
1,2,5-thiadiazoles 1
Ar
CHXY
OH
C
N
Time
Yield
(%)c
Compound Ar
(t/h)
Mp (T/ЊC)
7, 8, 9, 10
1a
1b
C6H5
4
3
98
74
31–33c
(lit.,2 31.5–32.5)
Liquid
S4N4
–HX
4-MeC6H4
(lit.,2 27–28)
101–103c
97–98c
X
1c
1d
1e
4-O2NC6H4
3-O2NC6H4
4-BrC6H4
3
4
6
85
94
97
Ar
C
CHY
O
Ar
CHY
S
N
S
69–71c
–N
S
C
N
(lit.,2 74–75.5)
38–39c
N
S
N
O
1f
4-ClC6H4
4-FC6H4
6
3
98
98
N
(lit.,2 37.5–38.5)
35–37c
16
19
1g
(lit.,2 35–36.5)
83–85c
1h
1i
1j
1k
3-Cl-, 4-MeOC6H3 12
84
78
69
91
H
X
S
N
S4N4
129–131d
124–125d
159–161d
b
4-Y-C6H4 b
3
3
5
Ar
N
S
C
S
3-Y-C6H4
4-Y-biphenylb
S
N
N
O
N
a
b
c,d
Isolated yield. Y = 3-chloro-1,2,5-thiadiazol-4-yl.
Hexane and
EtOH were used as solvents for recrystallization, respectively.
17
–H+
The mechanism for the formation of compounds 1–3 is
uncertain as shown in a variety of the reactions with S4N4 pre-
viously studied.14 In order to determine the source of nitrogen
atoms of compounds 1–3, 15N-labelled hydroxylamine hydro-
chloride (15NH2OH HCl, 99 atom%) was used to prepare the
15N-labelled oxime 7f, from which 1f was obtained (Scheme 4).
X
Ar
S
N
C
N
S
–NH(SN)2SO
1, 2, 3
-
N
N
N
S
S
4-ClC6H4
15N
Cl
15NH2OH•HCl
O
S4N4
18
12f
4-ClC6H4(C
=
15NOH)CHCl2
N
Scheme 5
7f
S
1f
The incorporation of an oxime nitrogen into the 1,2,5-
thiadiazoles is in contrast with the proposed mechanism for the
formation of 3,4-diphenyl-1,2,5-thiadiazole by reaction of ben-
Scheme 4
Mass spectral data for 1f obtained from the 15N-labelled oxime
7f shows the fragments having mass number (m/z) 231 (97.6%,
Mϩ) and 233 (76.5%, Mϩ ϩ 2), whereas that of 1f obtained
from 15N-unlabelled oxime 7f shows the fragments of mass
number (m/z) 230 (97.6%, Mϩ) and 232 (82.1, Mϩ ϩ 2). The
results indicate clearly that 15N atom of 7f is involved as one of
the nitrogen atoms of 1,2,5-thiadiazole ring. Since the mass
spectra of 1f formed via 15N-labelled and 15N-unlabelled oximes
7f show the fragments having (m/z) 138 and 137, corresponding
to the molecular weight of 15N-labelled and 15N-unlabelled 4-
chlorobenzonitriles, respectively, the N-5 atom of 1f is thought
to originate from the oxime nitrogen atom.
On the basis of these results, we propose the following path-
way in which nucleophilic attack of the hydroxy group of
dihalogeno ketoximes 7–10 on the tetravalent sulfur atom of
S4N4 gives the intermediate 16; subsequently, nucleophilic dis-
placement of the halogen atom on this by the amide ion
gives a cyclic intermediate 17. Deprotonation of this, followed
by cleavage of the N᎐S and N᎐O bonds gives an imide ion 18,
which then cyclizes to give 1 and HS3N3O. Alternatively, form-
ation of the intermediate 17 might be explained on the basis of
[4 ϩ 2] cycloaddition between S4N4 and the nitroso olefin 1915
which is believed to be readily formed in the presence of base
existing in the reaction mixtures (Scheme 5).
zil monooxime with S N , in which the ᎐NOH group was com-
᎐
4
4
pletely eliminated and the two nitrogen atoms of 1,2,5-
thiadiazole originate from S4N4.16
In conclusion, the geometry of 1-aryl-2,2-dihalogenoeth-
1
anone oximes has been assigned on the basis of H NMR spec-
troscopic data and a X-ray single crystallographic analysis in
which solid oximes appear to be Z-isomers. However, oily liquid
oximes exist as a mixture of E- and Z-isomers, showing prefer-
ence for the latter. We have demonstrated the synthetic utility of
S4N4 by isolation of excellent yields of 1,2,5-thiadiazoles having
a chlorine 1 or a bromine atom 2 at C-3 from the reactions with
1-aryl-2,2-dichloro- 7 and 1-aryl-2,2-dibromo-ethanone oximes
8, respectively. Similarly compounds 3 were obtained from the
reactions with 1-aryl-2-bromo-9 and 1-aryl-2-chloro-2-fluoro-
ethanone oximes 10 in fair yields. It has been shown that the
2-nitrogen atom of 1 has its origin in the oxime nitrogen atom
of 7.
Experimental
All melting points were determined on a Fisher–Johns melting
point apparatus and are uncorrected. IR spectra were obtained
on a Shimadzu IR-470 IR spectrophotometer for samples of
J. Chem. Soc., Perkin Trans. 1, 1998
111

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Table 7 Analytical, IR, and 1H NMR data for 3-aryl-4-chloro-1,2,5-thiadiazoles 1
Found (%) (Required)
Compound
(Formula)
C
H
N
S
νmax a/cmϪ1
δH (CDCl3; 80 MHz)
m/z (EI)
241 (100%, Mϩ), 243 (37.3,
1c
39.7
1.7
17.4
(17.4) (13.3)
13.3
1597, 1517, 1350, 1161, 979,
739, 704
8.44 (4 H, dd, J 15.8, 9.2,
ArH)
(C8H4ClN3O2S) (39.8) (1.7)
M
ϩ ϩ 2), 211 (60.6), 213
(23.1), 195 (27.4), 197 (10.4),
180 (7.0), 160 (29.9)
1d
39.75 1.7
(C8H4ClN3O2S) (39.8) (1.7)
17.4
(17.4) (13.3)
13.3
1523, 1338, 1258, 1174, 998,
899, 877, 835, 810, 765, 717, 8.34 (2 H, d, J 7.9, ArH),
7.64 (1 H, t, J 7.9, ArH),
241 (100%, Mϩ), 243 (37.9,
M
ϩ ϩ 2), 211 (22.6), 213 (8.3),
666
8.83 (1 H, s, ArH)
195 (51.9), 197 (19.3), 180
(9.3), 160 (26.2)
1h
41.4
2.3
10.7
(10.7) (12.2)
12.25
1590, 1504, 1343, 1280,
1159, 1062, 1018, 992, 813,
733, 698
3.83 (3 H, s, MeO), 7.00 (1 260 (100%, Mϩ), 262 (69.2,
H, d, J 8.7, ArH), 7.89 (1 H,
d, J 8.7, ArH), 8.02 (1 H, s,
ArH)
(C9H6Cl2N2OS) (41.4) (2.3)
M
ϩ ϩ 2), 264 (14.2, Mϩ ϩ 4),
245 (40.9), 247 (26.5), 199
(20.2), 167 (17.4)
1i
38.1
1.3
17.7
(17.8) (20.3)
20.4
1351, 1171, 880, 853, 839,
820, 561
8.10 (4 H, s, ArH)
314 (100, Mϩ), 316 (73.9,
(C10H4Cl2N4S2) (38.1) (1.3)
M
ϩ ϩ 2), 318 (17.4, Mϩ ϩ 4),
253 (63.0), 255 (26.6), 221
(19.8), 160 (28.5)
1j
38.1
1.3
17.75 20.4
(17.8) (20.3)
3067, 1339, 1304, 1251,
1170, 969, 826, 799
7.59 (1 H, t, J 14, ArH), 8.18 314 (100%, Mϩ), 316 (73.7,
(2 H, d, J 14, ArH), 8.66 (1
(C10H4Cl2N4S2) (38.1) (1.3)
M
ϩ ϩ 2), 318 (17.0, Mϩ ϩ 4),
H, s, ArH)
253 (54.9), 255 (22.3), 221
(15.8), 160 (30.2)
1k
49.0
2.05
14.3
(14.3) (16.4)
16.4
3079, 3046, 1607, 1458,
1350, 932, 799, 780
7.74 (4 H, d, J 8.2, ArH), 390 (100%, Mϩ), 392 (76.3,
8.06 (4 H, d, J 8.2, ArH)
(C16H8Cl2N4S2) (49.1) (2.1)
M
ϩ ϩ 2), 394 (20.5, Mϩ ϩ 4),
297 (65.5), 263 (30.9), 236
(51.9), 204 (72.6)
a IR spectra for 1c–h were taken neat and KBr was used for those of 1i–k
Table 8 Reaction times, yields, and melting points of 3-aryl-4-bromo-
1,2,5-thiadiazoles 2
dichloro-1-(3-nitrophenyl)ethanone 12d, pale yellow oil (Found:
C, 41.0; H, 2.15; Cl, 30.2; N, 5.9. C8H5Cl2NO3 requires C, 41.1;
H, 2.15; Cl, 30.3; N, 6.0%); νmax(KBr)/cmϪ1 1699 (C᎐O);
᎐
Compd. Ar
Time (t/h) Yield (%)a Mp (T/ЊC)
δH(CDCl3; 80 MHz) 6.63 (1 H, s, CHCl2), 7.76 (1 H, t, J 8,
ArH), 8.48 (2 H, d, J 8, ArH) and 8.89 (1 H, s, ArH); 1-(4-
bromophenyl)-2,2-dichloroethanone 12e, mp 61–62 ЊC (from
CCl4) (lit.,10 61.6–62 ЊC); 1-(4-chlorophenyl)-2,2-dichloro-
ethanone 12f, mp 47–48 ЊC (from CCl4) (Found: C, 42.95; H,
2.3; Cl, 47.8. C8H5Cl3O requires C, 43.0; H, 2.25; Cl, 47.6);
2a
C6H5
3
95
57–59c
(lit.,4 59–60)
27–29c
2b
2c
2d
2e
2f
4-MeC6H4
4-O2NC6H4
3-O2NC6H4
4-BrC6H4
3
3
3
4
3
92
99
98
97
96
101–102c
102–103c
82–84c
νmax(KBr)/cmϪ1 1701 (C᎐O); δ (CDCl ; 80 MHz) 6.58 (1 H, s,
66–67c
᎐
H
3
4-ClC6H4
(lit.,4 60–61)
58–60c
CHCl2) and 7.67 (4 H, dd, J 31, 8, ArH); 2,2-dichloro-1-(4-
fluorophenyl)ethanone 12g, mp 38–40 ЊC (from CCl4) (Found:
C, 46.4; H, 2.4; Cl, 34.3. C8H5Cl2FO requires C, 46.4; H, 2.4; Cl,
2g
2h
2i
4-FC6H4
3
3
5
4
12
3
98
94
95
86
93
49
86
4-MeOC6H4
3-MeOC6H4
2-Naphthyl
75–77c
34.25); νmax(KBr)/cmϪ1 1702 (C᎐O); δ (CDCl ; 80 MHz) 6.62
Liquid
᎐
H
3
2j
70–71c
(1 H, s, CHCl2), 7.17 (1 H, t, J 9, ArH) and 8.08 (2 H, m, ArH);
1-(3-chloro-4-methoxyphenyl)-2,2-dichloroethanone 12h, mp
71–73 ЊC (from CCl4) (lit.,19 72–73 ЊC); 1,4-bis(dichloro-
acetyl)benzene 12i, mp 154–156 ЊC (from CHCl3) (Found: C,
40.0; H, 2.0; O, 10.7. C10H6Cl4O2 requires C, 40.0; H, 2.0; O,
b
2k
2m
2n
4-Y-C6H4b
135–137d
128–129d
176–178d
3-Y-C6H4
4-Y-biphenyl-4-ylb
5
a
b
c,d
Isolated yield. Y = 3-bromo-1,2,5-thiadiazol-4-yl.
Hexane and
10.7%); νmax(KBr)/cmϪ1 1690 (C᎐O); δ (CDCl –[2H ]-DMSO);
EtOH were used as solvents for recrystallization, respectively.
᎐
H
3
6
80 MHz) 7.81 (2 H, s, CHCl2), 8.23 (4 H, s, ArH); 1,3-
bis(dichloroacetyl)benzene 12j, oil (Found: C, 40.0; H, 2.0; O,
10.8. C10H6Cl4O2 requires C, 40.0; H, 2.0; O, 10.7%); νmax(KBr)/
KBr pellets or thin films. 1H NMR spectra were determined on
a Brüker 80 MHz spectrometer using tetramethylsilane as
internal standard; J values are given in Hz. Mass spectra were
obtained by electron impact at 70 eV at the Inter-University
Center for Natural Sciences Research Facilities. Elemental
analyses were determined by the Korea Basic Science Center.
Column chromatography was performed on silica gel (Merck,
70-230, ASTM).
cmϪ1 1700 (C᎐O); δ (CDCl –[2H ]-DMSO; 80 MHz) 7.60 (2 H,
᎐
H
3
6
s, 2CH), 7.70 (1 H, t, J 8, ArH), 8.33 (2 H, d, J 8, ArH) and 8.75
(1 H, s, ArH); 4,4Ј-bis(dichloroacetyl)biphenyl 12k mp 162–
164 ЊC (from CHCl3) (Found: C, 51.15; H, 2.7; O, 8.6.
C16H10Cl4O2 requires C, 51.1; H, 2.7; O, 8.5%); νmax(KBr)/cmϪ1
1693 (C᎐O); δ (CDCl –[2H ]-DMSO; 80 MHz) 7.80 (2 H, s,
᎐
H
3
6
Tetrasulfur tetranitride was prepared by the reaction of sul-
fur monochloride with ammonia gas at room temperature.17
1-Aryl-2,2-dichloroethanones 12 were prepared according to
literature procedures10 except for the amount of chlorine gas
employed (7–10 equiv.) and the reaction temperature (40–
59 ЊC): 2,2-dichloro-1-phenylethanone 12a,18 liquid (Found: C,
50.75; H, 3.2; Cl, 37.0. C8H6Cl2O requires C, 50.9; H, 3.2; Cl,
CHCl2), 7.49 and 7.83 (8 H, 2 d, J 8.3, ArH). 1-Aryl-2,2-
dibromoethanones 13 were prepared by the literature
methods11: 2,2-dibromo-1-phenylethanone 13a mp 36–37 ЊC
(from CCl4) (lit.,11 36 ЊC); 2,2-dibromo-1-(4-methylphenyl)-
ethanone 13b, mp 99–100 ЊC (from CCl4) (lit.,11 98–99 ЊC); 2,2-
dibromo-1-(4-nitrophenyl)ethanone 13c, mp 54–55 ЊC (from
CCl4) (lit.,11 54–55 ЊC); 2,2-dibromo-1-(3-nitrophenyl)ethanone
13d, mp 54–55 ЊC (from CCl4) (lit.,11 55–56 ЊC; 1-(4-bromo-
phenyl)-2,2-dibromoethanone 13e, mp 91–92 ЊC (from CCl4)
(lit.,11 93–94 ЊC); 1-(4-chlorophenyl)-2,2-dibromoethanone 13f,
mp 92–93 ЊC (from CCl4) (lit.,11 93–94 ЊC); 2,2-dibromo-1-(4-
fluorophenyl)ethanone 13g, oil (Found: C, 32.5; H, 1.7; O, 5.4.
37.5%); νmax(KBr)/cmϪ1 1705 (C᎐O): δ (CDCl ; 80 MHz) 6.84
᎐
H
3
(1 H, s, CHCl2), 7.53 (3 H, m, Ph) and 8.08 (2 H, m, Ph); 2,2-
dichloro-1-(4-methylphenyl)ethanone 12b, mp 55–56 ЊC (from
CCl4) (lit.,10 54.5–55.3 ЊC); 2,2-dichloro-1-(4-nitrophenyl)-
ethanone 12c, mp 27–28 ЊC (from CCl4) (lit.,10 27–28 ЊC); 2,2-
112
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
Table 9 Analytical, IR, and 1H NMR data for 3-aryl-4-bromo-1,2,5-thiadiazoles 2
Found (%) (Required)
Compound
(Formula)
C
H
N
S
νmax a/cmϪ1
δH(CDCl3; 80 MHz)
m/z (EI)
2a
39.8
2.1
11.6
13.4
3060, 1442, 1353, 1147, 966,
835
3025, 1615, 1521, 1451,
1410, 1349, 1253, 1189,
1160, 1141, 1040, 1028, 982,
820
1597, 1517 (s), 1349 (s),
1331, 1313, 1297, 1163, 981,
860, 853, 835, 716
3091, 1613, 1532, 1491,
1344, 1262, 1162, 1094,
1078, 1011, 826, 803, 723
1590, 1498, 1450, 1398,
1350, 1142, 958, 813
7.48 (3 H, m, PhH), 7.92 (2 240 (46.6%, Mϩ), 242 (50.3,
(C8H5BrN2S)
2b
(39.85) (2.1)
42.4 2.8
(42.4) (2.8)
(11.6) (13.3)
11.0 12.6
(11.0) (12.6)
H, m, PhH)
ϩ ϩ 2), 135 (100)
2.42 (3 H, s, Me), 7.56 (4 H, 254 (57.2%, Mϩ), 256 (44.0,
M
(C9H7BrN2S)
dd, J 42, 8, ArH)
M
ϩ ϩ 2), 149 (100)
2c
33.6
1.4
14.7
(14.7) (11.2)
11.2
8.23 (4 H, dd, J 14, 8, ArH)
285 (29.2%, Mϩ), 287 (27.5,
M
ϩ ϩ 2), 160 (100)
(C8H4BrN3O2S) (33.6) (1.4)
2d
33.6
1.4
14.7
(14.7) (11.2)
11.2
7.67 (1 H, t, J 7, ArH), 8.32
(2 H, d, J 7, ArH), 8.83 (1 H,
s, ArH)
285 (31.6%, Mϩ), 287 (29.5,
ϩ ϩ 2), 160 (100)
(C8H4BrN3O2S) (33.6) (1.4)
M
2e
30.0
(30.0) (1.3)
1.3
8.7
10.05
7.69 (4 H, dd, J 17, 8, ArH)
318 (44.0%, Mϩ), 320 (89.3,
M
ϩ ϩ 2), 322 (39.9, Mϩ ϩ 4),
(C8H4Br2N2S)
(8.75) (10.0)
213 (100), 215 (95.1)
2f
34.8
1.45
10.1
(10.2) (11.6)
10.8 12.4
(10.8) (12.4)
11.7
1597, 1502, 1451, 1348,
1145, 1092, 1019, 967, 827
3086, 1602, 1517, 1452,
1348, 1237, 1161, 963, 835
8.25 (4 H, dd, J 18, 7, ArH)
274 (18.2%, Mϩ), 276 (22.8,
(C8H4BrClN2S) (34.9) (1.5)
M
ϩ ϩ 2), 169 (100)
2g
37.0
(37.1) (1.6)
1.55
7.14 (2 H, m, ArH), 7.87 (2 258 (73.0%, Mϩ), 260 (73.8,
H, m, ArH)
ϩ ϩ 2), 153 (100), 137
(23.1), 139 (23.8), 121 (30.9)
3.86 (3 H, s, OMe), 7.36 (4 270 (99.2%, Mϩ), 272 (100,
H, dd, J 17, 8, ArH)
ϩ ϩ 2), 165 (71.7), 150
(22.8), 133 (45.6)
3.87 (3 H, s, MeO), 7.03 (1 270 (60.9%, Mϩ), 272 (63.6,
(C8H4BrFN2S)
M
2h
39.8
(39.9) (2.6)
2.6
10.3
11.9
1453, 1349, 1302, 1258,
1181, 1143, 1030, 963, 822
(C9H7BrN2OS)
(10.3) (11.8)
M
2i
39.85 2.6
(39.9) (2.6)
10.3
11.9
3009, 1603, 1585, 1460,
1361, 1250, 1150, 1052,
1003, 863, 791
3056, 1593, 1475, 1331,
1140, 1106, 982, 931, 858,
813, 749
(C9H7BrN2OS)
(10.3) (11.8)
H, m, ArH), 7.47 (3 H, m,
ArH)
M
ϩ ϩ 2), 165 (100)
2j
49.4
(49.5) (2.4)
2.4
9.5
(9.6)
11.1
(11.0)
7.50 (2 H, m, ArH), 7.85 (4 290 (16.2%, Mϩ), 292 (15.3,
(C12H7BrN2S)
H, m, ArH), 8.47 (1 H, s,
ArH)
8.06 (4 H, s, ArH)
M
ϩ ϩ 2), 153 (100)
402 (51.2%, Mϩ), 404 (100,
2k
29.75 1.0
13.8
15.9
3042, 1590, 1465, 1338, 967,
840, 742
(C10H4Br2N4S2) (29.7) (1.0)
(13.9) (15.9)
M
ϩ ϩ 2), 406 (56.7, Mϩ ϩ 4),
297 (47.8), 299 (51.0), 265
(11.6), 267 (11.7), 160 (33.9)
2l
29.8
1.0
13.8
(13.9) (15.9)
15.9
3072, 1342 (s), 1315, 1251,
1168, 966, 821, 794, 689, 534
7.63 (1 H, t, J 15, ArH), 8.12 402 (48.2%, Mϩ), 404 (100,
(2 H, d, J 15, ArH), 8.46 (1
(C10H4Br2N4S2) (29.7) (1.0)
M
ϩ ϩ 2), 406 (52.2, Mϩ ϩ 4),
H, s, ArH)
297 (48.7), 299 (50.0), 265
(21.8), 267 (25.8), 160 (56.1)
480 (49.6%, Mϩ), 482 (100,
2m
40.1
1.7
11.6
13.4
3088, 3045, 1603, 1466,
7.89 (8 H, dd, J 13.6, 8.3,
ArH)
(C16H8Br2N4S2) (40.0) (1.7)
(11.7) (13.35) 1349, 928, 819, 789
M
ϩ ϩ 2), 484 (54.0, Mϩ ϩ 4),
376 (50.2), 378 (49.3), 344
(24.1), 346 (26.2), 204 (46.7)
a IR spectra of 2a–j were taken neat and KBr was used for those of 2k–m.
1.3; O, 6.7%); νmax(KBr)/cmϪ1 1693 (C᎐O); δ (CDCl )–[2H ]-
Table 10 Reaction times, yields, and melting points of 3-aryl-4-fluoro-
1,2,5-thiadiazoles 3
᎐
H
3
6
DMSO; 80 MHz) 7.59 (2 H, s, CHBr2), 7.69 (1 H, t, J 8, ArH),
8.32 (2 H, d, J 8, ArH) and 8.75 (1 H, s, ArH); 4,4Ј-bis-
(dibromoacetyl)biphenyl 13m, mp 216–217 ЊC (from CHCl3)
(Found: C, 34.6; H, 1.8; O, 5.8. C16H10Br4O2 requires C, 34.7;
Compound Ar
Time (t/h) Yield (%)a Mp (T/ЊC)b
3a
3b
3c
3d
C6H5
5
3
3
3
32
47
61
65
45–46 (lit.,2 45)
56–57
H, 1.8; O, 5.8%); νmax(KBr)/cmϪ1 1690 (C᎐O); δ (CDCl –[2H ]-
4-MeC6H4
4-BrC6H4
C6H5
᎐
H
3
6
76–77
DMSO; 80 MHz) 7.79 (2 H, s, CHBr2) and 7.50 and 7.80 (8 H,
2 d, J 8.2, ArH).
45–46 (lit.,2 45)
a Isolated yields. b CCl4 was used as a solvent for recrystallization.
General procedure for the preparation of 1-aryl-2,2-dichloro-
ethanone oximes 7
C8H5Br2FO requires C, 32.5; H, 1.7; O, 5.4%); νmax(KBr)/cmϪ1
To a solution of 12 (6–12 mmol) in EtOH (30 ml) was added
hydroxylamine hydrochloride (18–36 mmol). The mixture was
stirred for an appropriate time at room temperature. The hydro-
chloride salt disappeared slowly as the reaction proceeded and a
clean solution resulted. After solvent removal, water (30 ml)
was added to the reaction mixture to give white solids 7, which
were filtered off and recrystallized from CHCl3. When, upon
addition of water, yellowish white liquids formed at the bottom
of the flask, the mixtures were extracted with EtOAc (100
ml × 2) an the extracts dried (MgSO4). Evaporation of the
extracts gave residues which were chromatographed (silica gel
column: 2 × 10 cm) with benzene as eluent to give compounds 7
contaminated with 12. The crude oximes 7c and 7e were
recrystallized from CHCl3 and that of 7f from CCl4. Yields,
reaction times and melting points of compounds 7 are summar-
ized in Table 1.
1693 (C᎐O); δ (CDCl ; 80 MHz) 6.61 (1 H, s, CHBr ), 7.14 (2 H,
᎐
H
3
2
t, J 8.3, ArH) and 8.16 (2 H, dd, J 8.3, 3.5, ArH); 2,2-dibromo-
1-(4-methoxyphenyl)ethanone 13h, mp 92–93 ЊC (from CCl4)
(lit.,20 92–93 ЊC); 2,2-dibromo-1-(3-methoxyphenyl)ethanone 13i,
oil (Found: C, 35.05; H, 2.6; O, 10.4. C9H8Br2O2 requires C,
35.1; H, 2.6; O, 10.4%); νmax(KBr)/cmϪ1 1693 (C᎐O); δ (CDCl ;
᎐
H
3
80 MHz) 3.26 (3 H, s, MeO), 6.59 (1 H, s, CHBr2) and 6.61–7.11
(4 H, m, ArH); 2,2-dibromo-1-(2-naphthyl)ethanone 13j, mp
100–102 ЊC (from CCl4) (lit.,11 101–102 ЊC); 1,4-bis(dibromo-
acetyl)benzene 13k, mp 166–168 ЊC (from CHCl3) (Found:
C, 25.15; H, 1.3; O, 6.7. C10H5Br4O2 requires C, 25.1; H, 1.3;
O, 6.7%); νmax(KBr)/cmϪ1 1690 (C᎐O); δ (CDCl –[2H ]-DMSO;
᎐
H
3
6
80 MHz) 7.81 (2 H, s, CHBr2) and 8.23 (4 H, s, ArH); 1,3-
bis(dibromoacetyl)benzene 13l, mp 54–55 ЊC (from CHCl3)
(Found: C, 25.1; H, 1.3; O, 6.8. C10H6Br4O2 requires C, 25.1; H,
J. Chem. Soc., Perkin Trans. 1, 1998
113

View Article Online
Table 11 Analytical, IR, and 1H NMR data for 3-aryl-4-fluoro-1,2,5-thiadiazoles 3
Found (%) (Required)
Compd.
(Formula)
C
H
N
S
νmax a/cmϪ1
δH(CDCl3; 80 MHz)
m/z (EI)
3b
55.6
(55.7) (3.6)
3.6
14.4
(14.4) (16.5)
16.6
3072, 1613, 1510, 1435,
1302, 1284, 1190, 1037, 823,
736
3071, 1588, 1495, 1445,
1309, 1124, 958, 810
2.35 (3 H, s, Me), 7.54 (4 H, 194 (100%, Mϩ), 149 (1.06),
(C9H7FN2S)
dd, J 49, 8, ArH)
116 (2.2)
3c
37.05 1.55
(37.1) (1.6)
10.8
(10.8) (12.4)
12.4
7.66 (4 H, dd, J 22, 8, ArH)
258 (100%, Mϩ), 260 (94.7,
(C8H4BrFN2S)
M
ϩ ϩ 2), 215 (2.43), 197
(12.1), 182 (4.3)
a IR spectra were taken neat.
2,2-Dichloro-1-phenylethanone oxime 7a. E/Z mixture (46:54)
(Found: C, 47.0; H, 3.5; N, 6.9. C8H7Cl2NO requires C, 47.1; H,
3.5; N, 6.9%); νmax(neat)/cmϪ1 3296 (OH), 3056 and 1599;
δH(CDCl3; 80 MHz) 6.48 and 7.40 (1 H, 2 s, CHCl2), 7.36 (3 H,
m, ArH), 7.71 (2 H, m, ArH) and 9.61 (1 H, s, br, OH); m/z (EI)
203 (100%, Mϩ), 205 (66.2, Mϩ ϩ 2) and 207 (9.8, Mϩ ϩ 4).
2,2-Dichloro-1-(4-methylphenyl)ethanone oxime 7b. E/Z mix-
ture (41:59) (Found: C, 49.6; H, 4.2; N, 6.4. C9H9Cl2NO
requires C, 49.6; H, 4.2; N, 6.4%); νmax(neat)/cmϪ1 3296 (OH),
3040 and 1603; δH(CDCl3; 80 MHz) 2.33 (3 H, s, Me), 6.45 and
7.30 (1 H, 2 s, CHCl2), 7.38 (4 H, dd, J 16, 8, ArH) and 8.82 (1 H,
s, OH); m/z (EI) 217 (100%, Mϩ), 219 (67.3, Mϩ ϩ 2) and 221
(11.4, Mϩ ϩ 4).
2,2-Dichloro-1-(4-nitrophenyl)ethanone oxime 7c. Z-form
(Found: C, 38.5; H, 2.45; N, 11.2, C8H6Cl2N2O3 requires C,
38.6; H, 2.4; N, 11.25%); νmax(neat)/cmϪ1 3216 (OH), 3040, 1600,
1520s and 1346s; δH(CDCl3–[2H6]-DMSO; 80 MHz) 7.58 (1 H,
s, CHCl2), 8.12 (4 H, dd, J 20, 7, ArH) and 13.07 (1 H, s, OH);
m/z (EI) 248 (100%, Mϩ), 250 (65.9, Mϩ ϩ 2) and 252 (10.5,
Mϩ ϩ 4).
36.4; H, 2.45; N, 8.5; O, 9.8. C10H8Cl4N2O2 requires C, 36.4; H,
2.4; N, 8.5; O, 9.7%); νmax(KBr)/cmϪ1 3280 (OH), 3042 and
1610; δH(CDCl3–[2H6]-DMSO; 80 MHz) 7.18 (2 H, s, CHCl2),
7.50 (2 H, s, ArH), 7.84 (2 H, s, ArH), 11.93 (1 H, s, OH) and
12.70 (1 H, s, OH).
1,3-Bis(dichloroacetyl)benzene dioxime 7j. E/Z mixture
(33:67) (Found: C, 36.45; H, 2.45; N, 8.5; O, 9.6. C10H8Cl4N2O2
requires C, 36.4; H, 2.4; N, 8.5; O, 9.7%); νmax(KBr)/cmϪ1 3290
(OH), 3026 and 1600; δH(CDCl3–[2H6]-DMSO; 80 MHz) 6.47
and 7.34 (2 H, 2 s, 2 × CHCl2), 7.33 (2 H, m, ArH), 8.45 (2 H,
m, ArH) and 11.34 and 12.01 (2 H, 2 s, OH).
4.4Ј-Bis(dichloroacetyl)biphenyl dioxime 7k. Z-form (Found:
C, 47.4; H, 3.0; N, 6.8; O, 7.8. C16H12Cl4N2O2 requires C, 47.3;
H, 3.0; N, 6.9; O, 7.9%); νmax(KBr)/cmϪ1 3280 (OH), 3042 and
1602; δH(CDCl3–[2H6]-DMSO; 80 MHz) 7.70 (2 H, s, CHCl2),
7.49 (4 H, d, J 8.2, ArH), 7.79 (4 H, 2 d, J 8.2, ArH), 11.97 (1 H,
s, OH) and 12.63 (1 H, s, OH).
General procedure for the preparation of 3-aryl-4-chloro-1,2,5-
thiadiazoles 1
2,2-Dichloro-1-(3-nitrophenyl)ethanone oxime 7d. E/Z mix-
ture (36:64) (Found: C, 38.65; H, 2.5; N, 11.2. C8H6Cl2N2O3
requires C, 38.6; H, 2.4; N, 11.25%); νmax(neat)/cmϪ1 3392 (OH),
3040, 1610, 1520s and 1345s; δH(CDCl3–[2H6]-DMSO; 80 MHz)
6.41 and 7.60 (1 H, 2 s, CHCl2), 7.97 (4 H, m, ArH) and 9.50
and 10.12 (1 H, 2 s, OH); m/z (EI) 248 (100%, Mϩ), 250 (63.8,
Mϩ ϩ 2) and 252 (8.9, Mϩ ϩ 4).
1-(4-Bromophenyl)-2,2-dichloroethanone oxime 7e. Z-form
(Found: C, 33.9; H, 2.1; N, 4.9. C8H6BrCl2NO requires C, 34.0;
H, 2.1; N, 4.95%); νmax(neat)/cmϪ1 3312 (OH), 3040 and 1587;
δH(CDCl3–[2H6]-DMSO; 80 MHz) 7.50 (1 H, s, CHCl2), 7.52 (4
H, dd, J 20, 8, ArH), 12.42 (1 H, s, OH); m/z (EI) 281 (100%,
Mϩ), 283 (163.2, Mϩ ϩ 2), 285 (74.8, Mϩ ϩ 4), 287 (9.7,
Mϩ ϩ 6).
To a solution of 7 (0.63–2.3 mmol) in 1,4-dioxane (10–15 ml)
was added S4N4 (0.63–2.3 mmol). The mixture was heated at
reflux until no spot corresponding to 7 was observed on TLC
(RF ≅ 0.09, C6H6), after which the solvent was removed in
vacuo. The residue was extracted with CHCl3 (150 ml) and the
extracts were evaporated. Chromatography of the residue on a
silica gel column (2 × 12 cm) using hexane (200 ml) as eluent
gave sulfur and a minute amount of unknown compounds. Elu-
tion with hexane–benzene (3:1; 120 ml) gave compounds 1.
Elution with the same solvent mixture (1:1; 100 ml) gave
unchanged S4N4. Reaction times, yields, and melting points of
compounds 1 prepared are summarized in Table 6 and their
analytical, IR and 1H NMR data in Table 7.
1-(4-Chlorophenyl)-2,2-dichloroethanone oxime 7f. Z-form
(Found: C, 40.5; H, 2.5; N, 5.9. C8H6Cl3NO requires C, 40.3; H,
2.5; N, 5.9%); νmax(neat)/cmϪ1 3295 (OH), 3040 and 1588;
δH(CDCl3; 80 MHz). 7.42 (1 H, s, CHCl2), 7.45 (4 H, dd, J 23,
8, ArH) and 9.23 (1 H, s, br, OH); m/z (EI) 237 (100%, Mϩ), 239
(97.5, Mϩ ϩ 2) and 241 (30.8, Mϩ ϩ 4).
2,2-Dichloro-1-(4-fluorophenyl)ethanone oxime 7g. E/Z mix-
ture (16:84) (Found: C, 43.2; H, 2.7; N, 6.3. C8H6Cl2FNO
requires C, 43.3; H, 2.7; N, 6.3%); νmax(neat)/cmϪ1 3264 (OH),
3040 and 1597; δH(CDCl3; 80 MHz) 6.50 and 7.41 (1 H, 2 s,
CHCl2), 6.99 (2 H, m, ArH), 7.76 (2 H, m, ArH), 9.83 and 10.23
(1 H, 2 s, br, OH); m/z (EI) 221 (100%, Mϩ), 223 (65.5, Mϩ ϩ 2)
and 225 (11.1, Mϩ ϩ 4).
1-(3-Chloro-4-methoxyphenyl)-2,2-dichloroethanone oxime
7h. E/Z mixture (31:69) (Found: C, 40.2; H, 3.0; N, 5.2.
C9H8Cl3NO2 requires C, 40.3; H, 3.0; N, 5.2%); νmax(neat)/cmϪ1
3360 (OH), 3024 and 1594; δH(CDCl3; 80 MHz) 3.83 (3 H, s,
MeO), 6.48 and 7.37 (1 H, 2 s, CHCl2), 6.91 and 6.95 (1 H, 2 d, J
8.8, 8.2, ArH), 7.60 (2 H, m, ArH) and 8.50 (1 H, s, br, OH); m/z
(EI) 267 (100%, Mϩ), 269 (96.7, Mϩ ϩ 2) and 271 (32.1,
Mϩ ϩ 4).
General procedure for the preparation of 1-aryl-2,2-dibromo-
ethanone oximes 8
The experimental procedures are basically the same as those for
the preparation of 7. Reaction times, yields, and melting points
of compounds 8 are summarized in Table 8.
2,2-Dibromo-1-phenylethanone oxime 8a. E/Z mixture
(29:71) (Found: C, 32.8; H, 2.4; N, 4.75. C8H7Br2NO requires
C, 32.8; H, 2.4; N, 4.8%); νmax(neat)/cmϪ1 3298 (OH), 3046,
1491, 1399, 1281, 996, 950, 845, 781 and 694; δH(CDCl3; 80
MHz) 6.59 and 7.44 (1 H, 2 s, CHBr2), 7.42 (3 H, m, ArH), 7.73
(2 H, m, ArH) and 9.23 and 9.77 (1 H, 2 s, OH).
2,2-Dibromo-1-(4-methylphenyl)ethanone oxime 8b. Z-form
(Found: C, 35.2; H, 2.95; N, 4.5. C9H9Br2NO requires C, 35.2;
H, 2.95; N, 4.6%); νmax(neat)/cmϪ1 3297 (OH), 3040 and 1600;
δH(CDCl3–[2H6]-DMSO; 80 MHz) 2.35 (3 H, s, Me), 6.65 (1 H,
s, CHBr2), 7.58 (4 H, dd, J 54, 8, ArH) and 10.03 (1 H, s, OH);
m/z (EI) 305 (14.4% Mϩ), 307 (27.2, Mϩ ϩ 2), 309 (13.0, Mϩ ϩ 4)
and 134 (100).
2,2-Dibromo-1-(4-nitrophenyl)ethanone oxime 8c. Z-form
(Found: C, 28.5; H, 1.8; N, 8.3. C8H6Br2N2O3 requires C, 28.4;
H, 1.8; N, 8.3%); νmax(neat)/cmϪ1 3296 (OH), 3030, 1602, 1570s
and 1347s; δH(CDCl3)–[2H6]-DMSO; 80 MHz) 7.54 (1 H, s,
1,4-Bis(dichloroacetyl)benzene dioxime 7i. Z-form (Found: C,
114
J. Chem. Soc., Perkin Trans. 1, 1998

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CHBr2), 8.11 (4 H, dd, J 22, 8, ArH) and 10.87 (1 H, s, OH); m/z
(EI) 338 (0.8%, Mϩ), 340 (1.2, Mϩ ϩ 2), 342 (0.7, Mϩ ϩ 4) and
117 (100).
2,2-Dibromo-1-(3-nitrophenyl)ethanone oxime 8d. E/Z mix-
ture (36:64) (Found: C, 28.4; H, 1.8; N, 8.3. C8H6Br2N2O3
requires C, 28.4; H, 1.8; N, 8.3%); νmax(neat)/cmϪ1 3408 (OH),
3088, 1613, 1592s and 1350s; δH(CDCl3–[2H6]-DMSO; 80 MHz)
6.42 and 7.59 (1 H, 2 s, CHBr2), 7.96 (4 H, m, ArH), 9.29 and
9.88 (1 H, 2 s, OH); m/z (EI) 338 (3.2%, Mϩ), 340 (4.8, Mϩ ϩ 2),
342 (2.6, Mϩ ϩ 4) and 117 (100).
1-(4-Bromophenyl)-2,2-dibromoethanone oxime 8e. Z-form
(Found: C, 25.8; H, 1.6; N, 3.8. C8H6Br3NO requires C, 25.8; H,
1.6; N, 3.8%); νmax(KBr)/cmϪ1 3280 (OH), 3041 and 1588;
δH(CDCl3–[2H6]-DMSO; 80 MHz) 7.45 (1 H, s, CHBr2), 7.66 (4
H, dd, J 21, 8, ArH) and 11.10 (1 H, s, OH); m/z (EI) 368 (1.5%,
Mϩ), 370 (5.1, Mϩ ϩ 2), 372 (6.1, Mϩ ϩ 4), 374 (1.7, Mϩ ϩ 6)
and 182 (100).
1-(4-Chlorophenyl)-2,2-dibromoethanone oxime 8f. Z-form
(Found: C, 29.3; H, 1.85; N, 4.3. C8H6Br3NO requires C, 29.35;
H, 1.85; N, 4.3%); νmax(KBr)/cmϪ1 3292 (OH), 3040 and 1591;
δH(CDCl3–[2H6]-DMSO; 80 MHz) 7.42 (1 H, s, CHBr2), 7.59 (4
H, dd, J 35, 8.4, ArH) and 12.59 (1 H, s, OH); m/z (EI) 325
(4.0%, Mϩ), 327 (6.7, Mϩ ϩ 2), 329 (4.8, Mϩ ϩ 4) and 136
(100).
2,2-Dibromo-1-(4-fluorophenyl)ethanone oxime 8g. E/Z mix-
ture (34:66) (Found: C, 30.9; H, 1.9; N, 4.55. C8H6Br2FNO
requires C, 30.9; H, 1.9; N, 4.5%); νmax(neat)/cmϪ1 3288 (OH),
3040 and 1598; δH(CDCl3–[2H6]-DMSO; 80 MHz) 6.46 and 7.24
(1 H, 2 s, CHBr2), 6.45 (4 H, m, ArH) and 8.63 and 9.40 (1 H, 2
s, OH); m/z (EI) 309 (2.0%, Mϩ), 311 (5.5, Mϩ ϩ 2), 313 (3.5,
Mϩ ϩ 4) and 151 (100).
2,2-Dibromo-1-(4-methoxyphenyl)ethanone oxime 8h. Z-form
(Found: C, 33.4; H, 2,8; N, 4.3. C9H9Br2NO requires C, 33.5; H,
2.8; N, 4.3%); νmax(KBr)/cmϪ1 3296 (OH), 3039 and 1603;
δH(CDCl3–[2H6]-DMSO; 80 MHz) 3.87 (3 H, s, MeO), 7.47 (1
H, s, CHBr2), 7.51 (4 H, dd, J 70, 8, ArH) and 10.63 (1 H, s,
OH); m/z (EI) 321 (3.5%, Mϩ), 323 (3.9, Mϩ ϩ 2), 325 (2.9,
Mϩ ϩ 4) and 135 (100).
General procedure for the preparation of 3-aryl-4-bromo-1,2,5-
thiadiazoles 2
To a solution of 8 (1.0–3.6 mmol) in 1,4-dioxane (15 ml) was
added S4N4 (1.0–4.2 mmol). The mixture was heated at reflux
until no spot corresponding to 8 was observed on TLC
(RF ≅ 0.2, C6H6). After solvent removal in vacuo from the reac-
tion mixture, the residue was chromatographed on a silica gel
column (2 × 10 cm, 70–230 mesh). Hexane (200 ml) as eluent
gave sulfur and hexane–benzene (4:1; 200 ml) gave unchanged
S4N4; subsequently the same mixture (2:1; 200 ml) gave com-
pounds 2. Reaction times, yields, and melting points of com-
pounds 2 are summarized in Table 8 and their analytical, IR,
and 1H NMR data in Table 9.
General procedure for the preparation of 1-aryl-2-bromo-2-
fluoroethanones8 14
To a solution of the appropriate 1-aryl-2-fluoroethanone9 13
(5.7–8.0 mmol) in glacial acetic acid (15–30 ml) was added
bromine (7.5–8.2 mmol). The mixture was stirred for 5–10 h at
40–50 ЊC and quenched when no spot corresponding to 13
appeared on TLC (RF ≅ 0.4, ethyl acetate–n-hexane, 1:4). The
reaction mixture was worked up as described in the literature.
Reaction times and yields of 14 are summarized in Table 5.
2-Bromo-2-fluoro-1-phenylethanone 14a, mp 55–56 ЊC (lit.,13
55 ЊC); 2-bromo-2-fluoro-1-(4-methylphenyl)ethanone 14b, mp
64–66 ЊC (Found: C, 46.7; H, 3.95; Br, 34.8. C9H8BrFO
requires C, 46.8; H, 3.9; Br, 34.6%); νmax(KBr)/cmϪ1 1698 (CO);
δH(CDCl3; 80 MHz) 2.41 (3 H, s, Me), 6.67 (d, 1 H, J 51,
CHBrF) and 7.75 (4 H, dd, J 39, 8, ArH); m/z (EI) 230 (51.6%,
Mϩ), 232 (52.9, Mϩ ϩ 2), 151 (32.6) and 91 (100); 2-bromo-2-
fluoro-1-(4-bromophenyl)ethanone 14c, mp 96–98 ЊC (Found: C,
32.4; H, 1.7; Br, 54.2. C8H5Br2FO requires C, 32.5; H, 1.7; Br,
54.0%); νmax(KBr)/cmϪ1 1702 (C᎐O); δ (CDCl ; 80 MHz) 6.69
᎐
H
3
(1 H, d, J 51, CHBrF) and 7.99 (4 H, d, J 8.4, ArH); m/z (EI)
294 (23.8%, Mϩ), 296 (47.1, Mϩ ϩ 2), 298 (19.2, Mϩ ϩ 4), 215
(100) and 217 (98.2); 2-chloro-2-fluoro-1-phenylethanone 14d,
mp 45–46 ЊC (lit.,13 45 ЊC).
2,2-Dibromo-1-(3-methoxyphenyl)ethanone oxime 8i. Z-form
(Found: C, 33.4; H, 2.8; N, 4.4. C9H9Br2NO requires C, 33.5; H,
2.8; N, 4.3%); νmax(KBr)/cmϪ1 3302, 1600, 1507, 1437, 1299,
1189, 1020, 961 and 832; δH(CDCl3–[2H6]-DMSO; 80 MHz)
3.87 (3 H, s, MeO), 7.09 (1 H, m, ArH), 7.48 (1 H, s, CHBr2),
7.52 (3 H, m, ArH) and 9.72 (1 H, s, OH); m/z (EI) 321 (1.9%,
Mϩ), 323 (2.3, Mϩ ϩ 2), 325 (1.7, Mϩ ϩ 4) and 135 (100).
2,2-Dibromo-1-(2-naphthyl)ethanone oxime 8j. Z-form
(Found: C, 40.1; H, 2.65; N, 4.05. C12H9Br2NO requires C, 40.0;
H, 2.6; N, 4.1%); νmax(KBr)/cmϪ1 3280 (OH), 3072 and 1597;
δH(CDCl3–[2H6]-acetone; 80 MHz) 7.45 (2 H, m, ArH), 7.83 (4
H, m, ArH), 8.16 (1 H, s, CHBr2), 8.68 (1 H, s, ArH) and 10.85
(1 H, s, OH); m/z (EI) 341 (2.7%, Mϩ), 343 (3.0, Mϩ ϩ 2), 345
(2.5, Mϩ ϩ 4) and 153 (100).
General procedure for the preparation of 1-aryl-2-bromo-9 and
1-aryl-2-chloro-2-fluoroethanone oximes 10
The experimental procedures are basically the same as those for
the preparation of 7 except for quenching of the reaction by
addition of water to the mixture when no spot corresponding to
13 had appeared on TLC (RF ≅ 0.4, ethyl acetate–hexane, 1:4).
Reaction times, yields, and melting points of 9 and 10 are sum-
marized in Table 5.
2-Bromo-2-fluoro-1-phenylethanone oxime 9a. Z-form (Found:
C, 41.4; H, 3.0; N, 6.0. C8H7BrFNO requires C, 41.4; H, 3.0; N,
6.0%); νmax(neat)/cmϪ1 3312 (OH), 3072, 1452, 1382, 1314,
1159, 1095, 1066, 954, 772 and 398; δH(CDCl3–[2H6]-acetone;
80 MHz) 7.35 (3 H, m, PhH), 7.56 (1 H, d, J 48, CHBrF), 7.64
(2 H, m, PhH) and 10.12 (1 H, s, OH).
1,4-Bis(dibromoacetyl)benzene dioxime 8k. (Found: C, 23.6;
H, 1.6; N, 5.6; O, 6.4. C10H8Br4N2O2 requires C, 23.65; H, 1.6;
N, 5.5; O, 6.3%); νmax(KBr)/cmϪ1 3280 (OH), 3042 and 1610;
δH(CDCl3–[2H6]-DMSO; 80 MHz) 7.18 (2 H, s, 2 × CHBr2),
7.50 (2 H, s, ArH), 7.84 (2 H, s, ArH), 11.93 (1 H, s, OH) and
12.70 (1 H, s, OH).
1,3-Bis(dibromoacetyl)benzene dioxime 8l. (Found: C, 23.7;
H, 1.6; N, 5.5; O, 6.2. C10H8Br4N2O2 requires C, 23.65; H, 1.6;
N, 5.5; O, 6.3%); νmax(neat)/cmϪ1 3296s, 3040, 2880, 1435, 1377,
1264, 1045, 979, 806 and 714; δH(CDCl3; 80 MHz) 6.43 (1 H, s,
CHBr2), 7.29 (1 H, s, CHBr2), 7.30 (2 H, m, ArH), 8.40 (2 H, m,
ArH), 9.21 (1 H, s, OH) and 9.89 (1 H, s, OH).
4,4Ј-Bis(dibromoacetyl)biphenyl dioxime 8m. (Found: C, 33.0;
H, 2.1; N, 4.75; O, 5.45. C16H12Br4N2O2 requires C, 32.9; H, 2.1;
N, 4.8; O, 5.5%); νmax(KBr)/cmϪ1 3285 (OH), 3040 and 1608;
δH(CDCl3–[2H6]-DMSO; 80 MHz) 7.66 (8 H, dd, J 24, 8.3,
ArH), 7.75 (2 H, s, 2 × CHBr2), 11.93 (1 H, s, OH) and 12.52 (1
H, s, OH).
2-Bromo-2-fluoro-1-(4-methylphenyl)ethanone oxime 9b. Z-
form (Found: C, 43.7; H, 3.7; N, 5.8. C9H9BrFNO requires C,
43.9; H, 3.7; N, 5.7%); νmax(neat)/cmϪ1 3296 (OH), 1607, 1514,
1475, 1443, 1094, 1063, 957, 820 and 746; δH(CDCl3–
[2H6]-acetone; 80 MHz) 2.35 (3 H, s, Me), 7.50 (1 H, d, J 50,
CHBrF), 7.61 (4 H, dd, J 43, 8, ArH) and 11.12 (1 H, s, OH);
m/z (EI) 245 (20.4%, Mϩ), 247 (17.4, Mϩ ϩ 2) and 123 (100).
2-Bromo-2-fluoro-1-(4-bromophenyl)ethanone oxime 9c. Z-
form (Found: C, 30.85; H, 1.9; N, 4.5. C8H6Br2FNO requires
C, 30.9; H, 1.9; N, 4.5%); νmax(neat)/cmϪ1 3298 (OH), 1603,
1509, 1430, 1045, 972, 896, 880 and 753; δH(CDCl3–[2H6]-
acetone; 80 MHz) 7.53 (1 H, d, J 48, CHBrF), 7.58 (4 H, dd, J
15, 8, ArH) and 10.94 (1 H, s, OH).
2-Chloro-2-fluoro-1-phenylethanone oxime 10. E/Z mixture
(Found: C, 51.15; H, 3.8; N, 7.45; O, 8.6. C8H7ClFNO requires
C, 51.2; H, 3.8; N, 7.5; O, 8.5%); νmax(neat)/cmϪ1 3312 (OH),
3072, 1572, 1470, 1101, 1066, 967 and 797; δH(CDCl3; 80 MHz)
6.71 and 7.54 (1 H, 2 d, J 48, CHClF), 7.62 (2 H, m, PhH), 7.34
J. Chem. Soc., Perkin Trans. 1, 1998
115

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(3 H, m, PhH), 9.59 and 10.04 (1 H, 2 s, OH); m/z (EI) 187
(31.8%, Mϩ), 189 (11.7, Mϩ ϩ 2), 120 (65.4) and 77 (100).
References
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General procedure for the preparation of 3-aryl-4-fluoro-1,2,5-
thiadiazoles 3
3 (a) L. M. Weinstock, P. Davis, B. Handelsman and R. Tull, J. Org.
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To a solution of 14 (1.5–1.6 mmol) in 1,4-dioxane (15 ml) was
added S4N4 (1.5–1.6 mmol). The mixture was heated at reflux
until no spot corresponding to 14 was observed on TLC
(RF ≅ 0.18, C6H6). After removal of the solvent in vacuo from
the reaction mixture, the residue was chromatographed on a
silica gel column (2 × 10 cm). Hexane (200 ml) as eluent gave a
sulfur and hexane–benzene (4:1; 200 ml) gave unchanged S4N4.
Subsequent elution with the same solvent mixture (2:1; 200 ml)
gave compounds 3. Reaction times, yields, and melting points
of compounds 3 are summarized in Table 10, and their ana-
lytical, IR, and 1H NMR data in Table 11.
8 D. R. Baker and A. D. Gutman, U.S. Patent 4 441 916/1984 (Chem.
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9 When the reaction of 11a with hydroxylamine hydrochloride was
carried out at reflux temperature, a mixture of 7a, 5a, and 2,2,2-
trichloro-1-phenylethanone oxime was formed.
X-Ray structure analysis of compound 7f
Crystal data: C8H6Cl3NO, M = 238.49, Triclinic, a = 6.467
(3), b = 7.218 (2), c = 11.038 (5) Å, α = 85.79 (3), β = 74.33 (4),
γ = 76.13 (3)Њ, V = 481.6 (3) Å3 [by least-squares refinement on
diffractometer angles for 25 automatically centred reflections
with 23 р 2θ р 30Њ, λ = 0.710 96 Å, T = 293 (2) K], space group
10 R. N. McDonald and R. C. Cousine, J. Org. Chem., 1980, 45,
2976.
P1 Z = 2, Dx = 1.645 g cmϪ3, colourless crystals were grown
¯
11 (a) V. P. Kravets, G. I. Chervenyuk and G. V. Grinev, Zh. Org. Khim.,
1966, 2, 1244; (b) K. Kim, J. Cho and S. C. Yoon, J. Chem. Soc.,
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from CHCl3, F(000) = 240.00, µ(Mo-Kα) = 9.1 cmϪ1
.
Data collection and processing. An Enraf-Nonius CAD-4 dif-
fractometer, graphite-monochromated Mo-Kα radiation, ω/2θ
scans with ω scan width (0.65 ϩ 0.35 tan θ)Њ; 1536 reflections
measured (1.8 р θ р 25Њ, 0 р h р 7, Ϫ8 р k р 8, Ϫ12 р l
р 13), giving 1404 with I у 2σ(I ).
12 X. Creary, J. Org. Chem., 1987, 52, 5026.
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and S. Mataka, Chem. Lett., 1976, 627.
Structure solution and refinement. Automatic direct
methods21 (all non-H atoms). Full-matrix least-squares refine-
ment22 on F2 with all non-H atoms anisotropic; hydrogen
atoms were located from the successive electron density maps
and their positions and isotropic thermal parameters were
refined with no constraint. Final R1 [I у 2σ(I)] = 0.0345; wR2
[all data] = 0.1225, S[F2] = 0 for 119 refined parameters (R
indices defined in ref. 21). The final ∆F synthesis showed no
peaks outside the range Ϫ0.417→ϩ0.528 e ÅϪ3. Fig. 1 was
produced using SHELXTL/PC.23 Atomic coordinates and
equivalent isotropic and anisotropic displacement parameters,
and bond distances and angles, have been deposited at the
Cambridge Crystallographic Data Centre and are available on
request. Any such request should be accompanied by a full
bibliographic citation for this work together with the reference
number 207/156.†
15 The formation of the nitroso olefins 19 in the presence of NaHCO3
or Na2CO3 was confirmed by trapping experiments.
16 S. Mataka, K. Takahashi, S. Ishii and M. Tashiro, J. Chem. Soc.,
Perkin Trans. 1, 1979, 2905.
17 Gmelin’s Handbook of Inorganic Chemistry, Sulfur-Nitrogen
Compounds, Part 2 B, ed. B. Heibel, Springer-Verlag, Berlin, 8th
edn., 1984, ch. 5, p.127.
18 F. Weygand and H. J. Bestmann, Chem. Ber., 1957, 90, 1230.
19 K. Kurosawa and K. Yamaguchi, Bull. Chem. Soc. Jpn, 1981, 54,
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20 G. Weber, S. Hauptmann, H. Wilde and G. Mann, Synthesis, 1983,
3, 191.
21 G. M. Sheldrick, SHELXS-86, Acta Crystallogr., Sect. A, 1990, 46,
467.
22 G. M. Sheldrick, SHELXS-93, University of Göttingen, Germany,
1993.
23 G. M. Sheldrick, SHELXTL/PC version 5.03, Siemens Analytical
Instrumentation Inc., Madison, WI, 1994.
Acknowledgements
The authors are grateful for the financial support by the center
for Basic Science Research Institute Program, Ministry of
Education (BSRI-96-3417).
Paper 7/04408I
Received 23rd June 1997
Accepted 11th September 1997
† For details of the deposition scheme, see ‘Instructions for Authors’,
J. Chem. Soc., Perkin Trans 1, available via the RSC web pages (http://
www.rsc.org/authors).
116
J. Chem. Soc., Perkin Trans. 1, 1998