Chemistry of 4-dicyanomethylene-1,2,6-thiadiazines

Article abstract of DOI:10.1039/b000964o

The chlorine atoms in 3,5-dichloro-4-dicyanomethylene-1,2,6-thiadiazine 1 are readily displaced by thiophenols in the presence of Huenig's base, the first at -78 °C and the second at 20 °C to give the orange mono- and bis-arylthio derivatives in high yiel

Full text of DOI:10.1039/b000964o

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Chemistry of 4-dicyanomethylene-1,2,6-thiadiazines
Panayiotis A. Koutentis and Charles W. Rees
Department of Chemistry, Imperial College of Science, Technology and Medicine, London,
UK SW7 2AY
1
Received (in Cambridge, UK) 3rd February 2000, Accepted 21st February 2000
The chlorine atoms in 3,5-dichloro-4-dicyanomethylene-1,2,6-thiadiazine 1 are readily displaced by thiophenols in
the presence of Hünig’s base, the first at Ϫ78 ЊC and the second at 20 ЊC to give the orange mono- and bis-arylthio
derivatives in high yield (Table 1). Similarly secondary amines give the red mono- and blue bis-amino compounds
in high yield (Table 2); piperidine, for example, gives the former at Ϫ78 ЊC and the latter at Ϫ30 ЊC. A low limit of
reactivity is reached with diisopropylamine which gives the mono derivative only, in low yield (30%). Reactions with
ammonia and with primary amines are complex since the amines formed can cyclise onto the adjacent cyano group,
aniline giving only a low yield of the pyrrolo[2,3-c][1,2,6]thiadiazine 8. The 4-dicyanomethylene compound 1 is more
reactive than the known 4-oxo analogue 2, but can suffer the added complications of cyano group cyclisation and
hydrolysis of dicyanomethylene to the keto group. 3,5-Dimorpholino-4-dicyanomethylene-1,2,6-thiadiazine 7c is
oxidized to the sulfoxide 9 with MCPBA or N2O4, and 9 reverts to 7c with triphenylphosphine–tetrachloromethane,
all in high yield. Thiadiazine 1 undergoes a complex reaction with DMSO at 20 ЊC to give the three furo[2,3-c]-
[1,2,6]thiadiazines 10, 11 and (tentatively) 12 which could all arise from the initial product 13 of displacement of
chlorine by DMSO, by cyclisation and sulfoxide type rearrangements. Mechanisms are proposed for all new
reactions.
We have recently described1 the synthesis of 3,5-dichloro-4-
dicyanomethylene-4H-1,2,6-thiadiazine† 1 by the addition of
SCl2 to TCNE, and compared 1 with the analogous 4-oxo com-
pound 2.2 The most characteristic reaction of 2 is the displace-
ment of its two chlorine atoms by a range of nucleophiles,2 and
we now describe the effect on such reactions of exchanging the
Scheme 1 Reagents and conditions: (i) ArSH (1.1 equiv.), EtNPri2
4-oxo group for the more powerfully electron-withdrawing and
(1.1 equiv.), DCM, Ϫ78 ЊC, 1 h; (ii) ArSH (1.1 equiv.), EtNPri2 (1.1
more reactive dicyanomethylene group.
equiv.), C6H6, 20 ЊC, 1 h; (iii) EtOH, H2O, 80 ЊC, 30 min, 78%
(Ar = 4-MeOC6H4).
Results and discussion
Reaction of 1 with thiophenols
were poorly soluble in chloroform, DCM and benzene, whilst
the bis(4-methoxyphenylthio) derivative 4d was obtained as a
foam from the usual recrystallisation solvents, 1,2-dichloro-
ethane and cyclohexane. Attempted recrystallisation from
aqueous ethanol gave 3,5-bis(4-methoxyphenylthio)-4H-1,2,6-
thiadiazin-4-one 5 (Ar = 4-MeOC6H4) in good yield (78%). This
showed the ready uncatalysed or self catalysed hydrolysis of
the dicyanomethylene group; the same transformation was
observed with DMSO.
The dichlorothiadiazine 1 reacts with thiophenols in the pres-
ence of a tertiary amine to afford mono- and di-substituted
derivatives 3 and 4 in good to excellent yields (Table 1, Scheme
1). Mono-substitution could be achieved at Ϫ78 ЊC whilst the
second chlorine was replaced smoothly at ca. 20 ЊC. A slight
excess of thiophenol was required since a little disulfide was
always formed by oxidation. In the absence of a tertiary amine
no reaction was observed between the thiophenols and thia-
diazine 1; diisopropylethylamine (Hünig’s base) was preferred
because of its non nucleophilic nature, low viscosity and low
density.
Reaction of 1 with amines
Since the reaction of thiadiazine 1 with ammonia and primary
amines proved to be complex (see below) we next investigated
its reactivity towards secondary amines. Both chlorine atoms
were smoothly displaced to give the red mono-amino deriv-
atives 6 and the blue bis-amino derivatives 7 (Table 2). Non-
sterically hindered amines displaced both chlorines very
readily; piperidine displaced the first chlorine at Ϫ78 ЊC and the
second at Ϫ30 ЊC. Thus considerable care was required to
The solubility of the products was noticeably affected by
the thiophenol substituents. The chloro derivatives 3c and 4c
† Whilst common nomenclature has been used in the Discussion,
a
more formal (IUPAC) nomenclature is used throughout the
Experimental section.
DOI: 10.1039/b000964o
J. Chem. Soc., Perkin Trans. 1, 2000, 1081–1088
This journal is © The Royal Society of Chemistry 2000
1081

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obtain the mono-amino derivatives with slow, monitored
addition of exactly two equivalents of the amine, below 0 ЊC.
Bulky amines gave lower yields of all the tertiary amines
and required more severe conditions for complete reaction. A
limit was reached with diisopropylamine where only the mono-
amino derivative 6g could be obtained, in a maximum yield of
30% with six equivalents of amine in refluxing DCM for three
hours. Refluxing this derivative 6g in neat diisopropylamine
gave some indication (TLC) that the bis-amino product was
being slowly formed, but it appeared to be unstable under the
reaction conditions and could not be isolated.
The reaction of thiadiazine 1 with N-methylaniline required
a relatively long time and an excess of amine for complete dis-
placement of the second chlorine, but the yield of the bis-amine
7e was high (87%). The slow reaction probably results more
from deactivation by the phenyl group than from steric effects.
Diphenylamine was so deactivated towards nucleophilic attack
that thiadiazine 1 was recovered unchanged after several days
treatment with it at reflux in DCM.
Attempts to displace both chlorine atoms of 1 with aniline or
ammonia led to complex reaction mixtures. With aniline, only a
deep red product was obtained in very low yield (5%) and was
tentatively assigned the bicyclic structure, 4-anilino-5-cyano-
7-phenyl-6-phenyliminopyrrolo[2,3-c][1,2,6]thiadiazine 8, on
spectroscopic grounds. This product could result from dis-
placement of both chlorine atoms by aniline, cyclisation of one
anilino group onto the neighbouring cyano group and exchange
of the imino group so formed by aniline (Scheme 2). Similar
cyclisations onto the nitrile carbon have been observed with
other primary amines such as 1,2-diaminobenzene and 1,8-
diaminonaphthalene.3 Such cyclisation cannot occur, of course,
in the reactions of secondary amines with 1 which are uncom-
plicated (Table 2). Treatment of 1 with ammonia gave no clean
Scheme 2 Reagents and conditions: (i) PhNH2, (4 equiv.) DCM, 45 ЊC,
12 h.
products and we therefore attempted to synthesize the amino
derivatives via a Gabriel synthesis.4 The reaction of 1 with
potassium phthalimide and 18-crown-6 in toluene was also
complex but both the mono- and bis-phthalimido derivatives
could be isolated in low yields (25 and 20% respectively).
Attempts to control the reaction to give exclusively the mono-
or bis-phthalimido thiadiazine were unsuccessful and their
deprotection was therefore not pursued.
Comparison of the reactivity of thiadiazine 1 and thiadiazinone 2
From the above results, thiadiazine 1 is seen to react with thio-
phenols to displace both chlorine atoms readily at room
temperature; the thiadiazinone 2 does the same,2 in keeping
with the strong nucleophilicity of the thiols. The bis(arylthio)-
thiadiazines 4 undergo further reaction in aqueous ethanol to
give the C-4 hydrolysed thiadiazinones. With amines, the
reactivity of 1 and 2 depends greatly on the nucleophilicity of
the amine. Sterically demanding amines such as diisopro-
pylamine or deactivated amines such as N-methylaniline react
much less readily, as expected. With reactive amines, thiadiazine
1 shows enhanced susceptibility towards displacement of
the second chlorine over thiadiazinone 2. Thus 1 reacts with
N-methylaniline to give the mono- and bis-derivatives 6e and 7e
at room temperature whereas 2 requires refluxing in neat
N-methylaniline for the second displacement to occur.2 The
reactions of 2 are cleaner than those of 1 since there is little
reactivity other than chlorine displacement. Where possible 1
can also suffer hydrolysis of the dicyanomethylene group or
cyclisation onto a cyano group, resulting in more complex
reactions.
Table 1 The mono and bis(arylthio)-1,2,6-thiadiazines 3a–d and 4a–d
(see Scheme 1)
Compound
Aryl
Yield (%)
3a
4a
3b
4b
3c
4c
3d
4d
C6H5
C6H5
76
92
69
93
96
85
74
98
4-MeC6H4
4-MeC6H4
4-ClC6H4
4-ClC6H4
4-MeOC6H4
4-MeOC6H4
Table 2 The mono and bis(amino)-1,2,6-thiadiazines 6a–g and 7a–f
Compound
R2NH
Equiv. of R2NH
Time/h
Temp./ЊC
Yield (%)
6a
7a
6b
7b
6c
7c
6d
7d
6e
7e
6f
Pyrrolidine
Pyrrolidine
Piperidine
Piperidine
Morpholine
Morpholine
Dibenzylamine
Dibenzylamine
N-Methylaniline
N-Methylaniline
Di-n-propylamine
Di-n-propylamine
Diisopropylamine
2
4
2
5
2
5
2
5
2
1
12
12
24
12
24
12
24
12
24
1
Ϫ5 to 20
Ϫ5 to 45
20 to 45
20 to 45
Ϫ5 to 45
20 to 45
Ϫ5 to 45
20 to 45
Ϫ5 to 20
20 to 45
Ϫ5 to 20
Ϫ5 to 45
45
77
84
81
78
83
76
74
81
85
87
74
82
30
12
2
4
7f
12
3
6g
6
1082
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Oxidation of 4-dicyanomethylene-1,2,6-thiadiazines
1,2,6-Thiadiazine sulfoxides and, more importantly, the sul-
fones have received considerable attention in various areas of
applied chemistry including the pharmaceutical,5 agro-
chemical6 and materials sectors.7 However, the oxidation of 3,5-
substituted-4H-1,2,6-thiadiazines has not been reported. The
oxidation of thiadiazine 1 with MCPBA or with dinitrogen tetra-
oxide was unsuccessful; neither sulfoxide nor starting material
could be recovered. We therefore turned to the oxidation of the
more “electron rich” 3,5-dimorpholinothiadiazine 7c; in spite
of the risk of N-oxidation, 7c was rapidly converted into the
S-oxide 9 in high yield, by the same reagents (Scheme 3). Both
Scheme 4
4-chloro-5-cyano-6-methylthioimino-6H-furo[2,3-c][1,2,6]thia-
diazine 10, 4-chloro-5-cyano-6-oxo-6H-furo[2,3-c][1,2,6]thia-
diazine 11 and, tentatively, 5-cyano-4-hydroxy-6-methylthio-
methylimino-6H-furo[2,3-c][1,2,6]thiadiazine 12 (Scheme 5).
Thiadiazine 1 (2 mmol) in DMSO (2 ml) after 3 h gave 7, 25 and
6% respectively and after 6 h gave 2, 29 and 9% respectively of
the three products. It is possible that the imine 10 was slowly
hydrolysed, or reacted further with DMSO, to give the lactone
11, though both products were observed (TLC) to form equally
rapidly at the start of the reaction.
Scheme 3 Reagents and conditions: (i) MCPBA (1.6 equiv.), DCM,
20 ЊC, (85%) or N2O4 (g), DCM, 20 ЊC, (95%); (ii) Ph3P (3.3 equiv.),
CCl4 (10 equiv.), DCM, 40 ЊC, 1 h (92%).
reactions were accompanied by a rapid colour change from
deep violet [λmax 543 nm (log ε 4.03)] to orange-red [λmax 454 nm
(log ε 3.24)]. In the reaction with dinitrogen tetraoxide care was
required in the work up procedure; any attempt to perform an
aqueous work up or to concentrate the reaction mixture led
to complex mixtures. Since an excess of N2O4 gas was always
used, careful monitoring (TLC) was also required; prolonged
reaction times led to complex mixtures.
The product 9 was obtained as orange needles, mp > 300 ЊC.
Both microanalysis and HRMS gave the formula C14H16N6O3S
and the location of the extra oxygen atom followed from the
spectroscopic data. The IR spectrum showed strong stretching
bands at 1129 and 1112 cmϪ1 supporting the presence of a sulf-
oxide, and the nitrile stretching at 2240 cmϪ1 was less intense
and of higher frequency than that of the starting material 7c
(2207 cmϪ1), indicative of less negative charge delocalised onto
the dicyanomethylene group. This was supported by the 13C
NMR data which showed that the resonance of the central
carbon of the dicyanomethylene group at 90.1 ppm was
deshielded compared to that of 7c (71.7 ppm). The 13C NMR
also showed that the molecule was symmetrical and that there
was a significant barrier to rotation of the morpholino groups
since four separate and well resolved carbon resonances at 66.1,
65.7, 48.4 and 45.6 ppm were observed, whereas in the starting
material 7c the morpholino groups showed only two resonances
at 66.1 and 48.6 ppm. These observations were paralleled in the
1H NMR spectra. The striking change in colour on oxidizing 7c
to the sulfoxide 9 may result from a much diminished delocal-
isation of electrons from the amino groups to the dicyano-
methylene group in the latter. The sulfoxide was reduced back
to thiadiazine 7c (92%) with triphenylphosphine and tetra-
chloromethane;8 triphenylphosphine oxide (94%) was also
isolated and the reaction was accompanied by the expected
colour change from orange-red to deep violet. Without tetra-
chloromethane there was no reaction, even on prolonged reflux
with the phosphine in DCM, and the reducing agent is presum-
ably a reactive species generated from the phosphine and tetra-
chloromethane; compare, for example, references 9 and 10. One
possible sequence is suggested in Scheme 4.
Scheme 5 Reagents and conditions: (i) DMSO, 20 ЊC, 3–6 h.
Compound 10 was obtained as deep red plates that were
thermally very stable, mp > 280 ЊC. Two strong UV absorption
bands, [λmax 488 nm (log ε 4.20) and 359 (4.21)], supported the
presence of the 1,2,6-thiadiazine ring system. Microanalysis
and HRMS gave the molecular formula C7H3ClN4OS2. LRMS
showed strong losses of 15 and 46 Da from the parent ion, m/z
258 (100%) to give 243 (29) and 212 (37) respectively. HRMS
assigned these losses to CH3 and CH2S and LSMS confirmed
that these two ions m/z 243 and 212 were direct fragments from
the parent ion. Furthermore the low mass ion of m/z 47 (28)
was identified as (CH3S)ϩ by HRMS and strongly supported
the presence of a methylthio group. A very weak ion at m/z 197
(2) was seen during the LSMS and tentatively supported the
connectivity of the methylthio group to a nitrogen atom,
CH3SN. 1H NMR revealed a single resonance (2.84 ppm) which
was assigned to that of the methylthio group. 13C NMR showed
seven separate carbon resonances indicating an unsymmetrical
molecule. The carbon resonance at 110.5 ppm was assigned to
the nitrile group and this was supported by a moderate nitrile
stretching band at 2233 cmϪ1 in the IR spectrum, whilst the
high field carbon resonance at 24.4 ppm was assigned to the
methylthio group. Based on the spectroscopic data the methyl-
thioimine structure 10 was assigned to this red compound.
However, this structure was very similar to that of lactone 11,
mp 109–113 ЊC, and yet the melting point of the imine 10
(> 280 ЊC) was much higher. X-Ray diffraction studies11 on
single crystals of the imine confirmed structure 10 and showed
that within the planar molecular sheets there are strong attract-
ive interactions between the nitrile nitrogens of one molecule
and the CH3SN sulfur of another (ca. 3.0 Å); presumably this
interaction, which cannot be present in the lactone 11, is
responsible for the large difference in their melting points.
Reaction of thiadiazine 1 with DMSO
Thiadiazine 1 reacted with neat DMSO at room temperature
to give a deep red mixture which, after aqueous work up
and chromatography, gave three compounds characterized as
J. Chem. Soc., Perkin Trans. 1, 2000, 1081–1088
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Compound 11 was obtained as bright yellow needles, mp
109–113 ЊC, which dissolved readily in DCM. The survival of
the 1,2,6-thiadiazine ring was supported by two UV absorption
bands at λmax 431 nm (log ε 4.27) and 407 (4.45). Microanalysis
and HRMS gave the molecular formula C6ClN3O2S. LRMS
showed a strong loss of 28 Da (CO) from the parent ion m/z 213
(100%) to give 185 (23); HRMS supported this assignment of
CO which suggested the presence of a carbonyl function. IR
spectroscopy showed strong carbonyl stretching at 1816 cmϪ1
typical for lactones, and strong nitrile stretching at 2230 cmϪ1
,
.
13C NMR spectroscopy showed six separate carbon resonances
indicating an unsymmetrical molecule; and one of the carbon
resonances could clearly be assigned to the nitrile at 110.5 ppm.
Compound 12 was obtained as a dark precipitate, mp >
280 ЊC, upon dilution of the reaction mixture with water.
Microanalysis and HRMS gave the molecular formula C8H6-
N4O2S2. Owing to the highly insoluble nature of compound 12
no NMR data were obtained. IR spectroscopy identified strong
nitrile stretching at 2213 cmϪ1, and a broad band at 3300 cmϪ1
indicating the presence of an OH or an NH group; no strong
evidence of carbonyl stretching bands was observed. HRMS
showed a weak parent ion m/z 254 (7%) which readily lost 15
and 46 Da to give the ions 239 (11) and 208 (14) which corre-
sponded to losses of CH3 and CH2S respectively. The spectro-
scopic data were insufficient to confirm a structure for this
compound, but the 3-hydroxy compound 12, or its keto tauto-
mer, were tentatively assigned as the most likely. Attempts
to acetylate the precipitate to improve its solubility were
unsuccessful.
The formation of the three products isolated 10, 11 and 12 is,
we believe, unprecedented, but a rational mechanistic scheme
is proposed (Scheme 6) based on the diverse chemistry of sulf-
oxides.12 DMSO is considered to act as a nucleophile, displacing
a chlorine in 1 to give the salt 13. This could cleave to give the
3-oxido anion 14 which is well set up to cyclise onto the neigh-
bouring cyano group. The resulting bicyclic species 17 could
then undergo the remaining transformations summarized in
Scheme 6. It is also possible that cyclisation could occur in the
first intermediate 13, accompanying the O–S bond cleavage in a
concerted manner, as shown in 20.
Scheme 6
Experimental†
All reactions were carried out under a dry nitrogen atmosphere.
Anhydrous magnesium sulfate was used for drying organic
extracts and volatiles were removed under reduced pressure.
Ether refers to diethyl ether and light petroleum refers to the
fraction bp 60–80 ЊC. Low temperature reactions were per-
formed using ice–salt water baths (Ϫ5 ЊC) or solid CO2–acetone
baths (Ϫ78 ЊC).
All reactions and column eluents were monitored by TLC
using commercial aluminium backed thin-layer chromato-
graphy (TLC) plates (Merck Kieselgel 60 F254). The plates were
observed under UV light at 254 and 350 nm. The technique of
dry flash chromatography was used throughout for all non-
TLC scale chromatographic separations using Sorbsil C60 M40
silica.
Melting points were determined using a Reichert Kofler hot-
stage apparatus. Solvents used for recrystallisation are indicated
after the melting point. UV spectra were obtained using a
Perkin-Elmer Lambda II spectrometer and inflections are iden-
tified by the abbreviation “inf ”. IR spectra were recorded on a
Perkin-Elmer 1710FT spectrometer and strong, medium and
weak peaks are represented by s, m and w respectively. 1H NMR
spectra were recorded on JEOL GSX 270 (at 270 MHz), Bruker
AM300WB (at 300 MHz) and Bruker AM500 (at 500 MHz)
machines. 13C NMR spectra were recorded on JEOL GSX 270
(at 68 MHz), Bruker AM300WB (at 76 MHz) and Bruker
RX-400 (at 100 MHz) machines. Deuterated solvents were used
for homonuclear lock and the signals are referenced to the
deuterated solvent peaks. Mass spectra were recorded on a VG
micromass 7070E or a VG Autospec “Q” mass spectrometer.
Microanalyses were performed on a Perkin-Elmer 2400 CHN
Analyser.
Reaction of (3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)propane-
dinitrile 1 with thiophenols
Monoarylthiothiadiazines 3. (See Scheme 1 and Table 1)
Typical procedure: to a stirred suspension of (3,5-dichloro-4H-
1,2,6-thiadiazin-4-ylidene)propanedinitrile
1 (207 mg, 0.9
mmol) in DCM (3 ml) at Ϫ78 ЊC, under nitrogen, thiophenol
(105 µl, 1.02 mmol) was added followed by the slow addition
of Hünig’s base (174 µl, 1 mmol) at Ϫ78 ЊC. After 1 h no
starting thiadiazine remained (TLC). Chromatography (light
petroleum–DCM, 1:1) gave (3-chloro-5-phenylthio-4H-1,2,6-
thiadiazin-4-ylidene)propanedinitrile 3a (208 mg, 76%) as
orange crystals, mp 138–140 ЊC (from cyclohexane) (Found: C,
47.7; H, 1.7; N, 18.2. C12H5ClN4S2 requires C, 47.4; H, 1.6; N,
18.4%); λmax(DCM)/nm 264 (log ε 3.95), 338 (4.00), 447 (4.20);
νmax(Nujol)/cmϪ1 3077w and 3052w (Ar CH), 2217s (CN),
1576w, 1519s, 1455s, 1282s, 1267s, 1146s, 1075s, 1023m, 999m,
812s, 762s, 753s, 702m, 690m, 628m; δH(270 MHz; CDCl3)
7.67–7.49 (5H, m, Ar H); δC(68 MHz; CDCl3) 153.37, 137.44,
136.43 (Ar C-2), 134.64, 131.75 (Ar C-4), 130.61 (Ar C-3),
126.22 (Ar C-1), 113.75 (CN), 113.14 (CN), 78.64 [C(CN)2];
m/z (EI) 304 (Mϩ, 58%), 277 (Mϩ Ϫ CHN, 17), 269 (Mϩ Ϫ Cl,
1084
J. Chem. Soc., Perkin Trans. 1, 2000, 1081–1088

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14), 246 (50), 242 (29), 237 (Mϩ Ϫ ClS, 20), 210 (35), 185 (13),
135 (C7H5NSϩ, 6), 123 (35), 109 (C6H5Sϩ, 100), 77 (C6H5ϩ, 35),
69 (24), 65 (62).
C-1), 113.98 (CN), 76.77 [C(CN)2]; m/z (EI) 378 (Mϩ, 15%), 320
(Mϩ Ϫ CNS, 4), 287 (2), 242 (26), 218 (24), 210 (8), 185 (13),
154 (4), 141 (23), 135 (C7H5NSϩ, 4), 128 (13), 123 (18), 109
(C6H5Sϩ, 100), 77 (C6H5ϩ, 40), 65 (51).
Similar treatment of 1 with the appropriate thiophenol gave
the following compounds:
Similar treatment of the monoarylthiothiadiazines 3 with
the appropriate thiophenol gave the following compounds:
[3,5-Bis(4-methylphenylthio)-4H-1,2,6-thiadiazin-4-ylidene]-
propanedinitrile 4b. Red-orange needles (93%), mp 154–155 ЊC
(from cyclohexane) (Found: C, 59.0; H, 3.7; N, 13.65. C20H14-
N4S3 requires C, 59.1; H, 3.45; N, 13.8%); λmax(DCM)/nm 230
(log ε 4.43), 266 (4.12), 345 (4.14), 480 (4.10); νmax(Nujol)/cmϪ1
3080w (Ar CH), 2209s and 2198m (CN), 1595w, 1494s, 1428s,
1398m, 1286s, 1179m, 1144m, 1069m, 1017m, 818s, 809s, 741s,
706s; δH(270 MHz; CDCl3) 7.49 (4H, d, J 8.2 Hz, Ar H-2), 7.34
(4H, d, J 7.9 Hz, Ar H-3), 2.48 (6H, s, CH3); δC(68 MHz;
CDCl3) 148.01, 141.87 (Ar C-4), 138.67, 136.32 (Ar C-2),
131.25 (Ar C-3), 123.40 (Ar C-1), 114.04 (CN), 76.50 [C(CN)2],
22.13 (CH3); m/z (EI) 406 (Mϩ, 64%), 348 (Mϩ Ϫ CNS, 18), 315
[3-Chloro-5-(4-methylphenylthio)-4H-1,2,6-thiadiazin-4-
ylidene]propanedinitrile 3b. Orange crystals (69%), mp 175–
178 ЊC (from cyclohexane) (Found: C, 49.0; H, 2.2; N, 17.5.
C13H7ClN4S2 requires C, 49.1; H, 2.2; N, 17.6%); λmax(DCM)/
nm 231 (log ε 4.10), 262 (3.86), 341 (3.94), 450 (4.13);
νmax(Nujol)/cmϪ1 3045w (Ar CH), 2217s (CN), 1596w, 1525s,
1494m, 1456s, 1286s, 1270s, 1149s, 1088m, 1075s, 812s, 756s,
700s, 633m, 600s; δH(270 MHz; CDCl3) 7.47 (2H, d, J 8.4 Hz,
Ar H-2), 7.36 (2H, d, J 7.9 Hz, Ar H-3), 2.50 (3H, s, CH3);
δC(68 MHz; CDCl3) 153.89, 142.46 (Ar C-4), 137.54, 136.38
(Ar C-2), 134.53, 131.51 (Ar C-3), 122.64 (Ar C-1), 113.81
(CN), 113.20 (CN), 78.62 [C(CN)2], 22.21 (CH3); m/z (EI) 318
(Mϩ, 7%), 303 (Mϩ Ϫ CH3, 0.5), 292 (Mϩ Ϫ CN, 2), 283
(Mϩ Ϫ Cl, 2), 257 (Mϩ Ϫ CClN, 56), 242 (34), 224 (9), 123
(Mϩ Ϫ C7H7, 18), 256 (16), 224 (Mϩ Ϫ C8H8NS2, 15), 199 (12),
(C7H7Sϩ, 49), 108 (C6H4Sϩ, 11), 91 (C7H7ϩ, 100), 77 (C6H5
50), 69 (23), 65 (34).
,
137 (37), 123 (C7H7Sϩ, 67), 91 (C7H7ϩ, 100), 79 (39), 77 (C6H5
36), 65 (19).
ϩ
ϩ
,
[3-Chloro-5-(4-chlorophenylthio)-4H-1,2,6-thiadiazin-4-
[3,5-Bis(4-chlorophenylthio)-4H-1,2,6-thiadiazin-4-ylidene]-
ylidene]propanedinitrile 3c. Orange crystals (96%), mp 190 ЊC
(from 1,2-dichloroethane–cyclohexane) (Found: C, 42.5; H, 1.3;
N, 16.3. C12H4Cl2N4S2 requires C, 42.6; H, 1.2; N, 16.6%);
λmax(DCM)/nm 233 (log ε 4.24), 262 (3.94), 339 (3.97), 445
(4.18); νmax(Nujol)/cmϪ1 3085w and 3053w (Ar CH), 2221s
(CN), 1574m, 1525s, 1456s, 1392m, 1285s, 1270s, 1150s, 1093s,
1081s, 1073s, 1012s, 838m, 823s, 807s, 758s, 746s, 700s, 630s;
δH(270 MHz; CDCl3) 7.45 (4H, s, Ar H); δC(68 MHz; CDCl3)
152.85, 138.63 (Ar C-4), 137.86 (Ar C-2), 137.50, 134.88, 131.06
(Ar C-3), 124.63 (Ar C-1), 113.72 (CN), 113.03 (CN), 78.58
[C(CN)2]; m/z (EI) 338 (Mϩ, 7%), 277 (Mϩ Ϫ CClN, 82), 242
(Mϩ Ϫ CCl2N, 71), 157 (13), 143 (C6H4ClSϩ, 53), 108 (C6H4Sϩ,
100), 99 (23), 76 (C6H4ϩ, 31), 69 (19), 63 (20).
[3-Chloro-5-(4-methoxyphenylthio)-4H-1,2,6-thiadiazin-4-
ylidene]propanedinitrile 3d. Orange crystals (74%), mp 110–
111 ЊC (from cyclohexane) (Found: C, 46.8; H, 2.1; N, 16.6.
C13H7ClN4OS2 requires C, 46.7; H, 2.1; N, 16.8%); λmax(DCM)/
nm 244 (log ε 4.27), 266 inf (4.00), 337 (3.94), 450 (4.15);
νmax(Nujol)/cmϪ1 3088w (Ar CH), 2213s (CN), 1589s, 1569m,
1505s, 1495s, 1445s, 1409m, 1289s, 1270s, 1255s, 1178s, 1145s,
1107m, 1072s, 1026s, 831s, 813s, 798m, 752s, 707s, 640m; δH(270
MHz; CDCl3) 7.41 (2H, d, J 8.9 Hz, Ar H-2), 6.97 (2H, d, J 8.9
Hz, Ar H-3), 3.84 (3H, s, CH3O); δC(68 MHz; CDCl3) 162.57
(Ar C-4), 154.44, 138.15 (Ar C-2), 137.50, 134.50, 116.38 (Ar
C-1), 116.26 (Ar C-3), 113.84 (CN), 113.23 (CN), 78.42
[C(CN)2], 56.19 (CH3O); m/z (EI) 334 (Mϩ, 14%), 319 (Mϩ Ϫ
CH3, 0.5), 308 (Mϩ Ϫ CN, 1), 303 (Mϩ Ϫ CH3O, 0.5), 299
(Mϩ Ϫ Cl, 0.5), 273 (Mϩ Ϫ CClN, 54), 258 (23), 230 (10), 139
(C7H7OSϩ, 100), 124 (C6H4OSϩ, 17), 96 (34), 76 (C6H4ϩ, 12), 70
(27), 63 (15).
propanedinitrile 4c. Orange crystals (85%), mp 176–176.5 ЊC
(from 1,2-dichloroethane–cyclohexane) (Found: C, 48.1; H, 1.5;
N, 12.3. C18H8Cl2N4S3 requires C, 48.4; H, 1.8; N, 12.6%);
λmax(DCM)/nm 232 (log ε 4.45), 266 (4.10), 344 (4.09), 473
(4.09); νmax(Nujol)/cmϪ1 3080w (Ar CH), 2186s (CN), 1573m,
1418s, 1392m, 1297s, 1281m, 1266m, 1139m, 1121m, 1089s,
1062s, 1016s, 833s, 823s, 734s, 703m, 650s; δH(270 MHz; CDCl3)
7.47 (4H, d, J 8.9 Hz, Ar H), 7.42 (4H, d, J 8.4 Hz, Ar H); δC(68
MHz; CDCl3) 147.43, 138.41 (Ar C-4), 138.25, 137.85 (Ar C-2),
130.88 (Ar C-3), 125.26 (Ar C-1), 113.87 (CN), 77.81 [C(CN)2];
m/z (EI) 446 (Mϩ, 10%), 411 (Mϩ Ϫ Cl, 1), 355 (2), 277 (Mϩ Ϫ
C7H4ClNS, 18), 242 (14), 175 (13), 157 (24), 143 (C6H4ClSϩ,
100), 123 (23), 111 (C6H4Clϩ, 12), 108 (C6H4Sϩ, 99), 99 (25), 76
(C6H4ϩ, 36), 69 (23), 63 (21).
[3,5-Bis(4-methoxyphenylthio)-4H-1,2,6-thiadiazin-4-
ylidene]propanedinitrile 4d. Red-orange foam (98%); νmax(film)/
cmϪ1 3092w (Ar CH), 2213m (CN), 1591s, 1573s, 1494s, 1461s,
1435s, 1295s, 1251s, 1174s, 1144s, 1107m, 1066m, 1029s, 1007m,
830s, 810m, 799s, 740s, 702s, 666m, 642s; δH(300 MHz; CDCl3)
7.46 (4H, d, J 8.9 Hz, Ar H-2), 6.98 (4H, d, J 8.9 Hz, Ar H-3),
3.86 (6H, s, CH3O); δC(76 MHz; CDCl3) 161.66 (Ar C-4),
147.82, 138.11, 137.53 (Ar C-2), 116.58 (Ar C-1), 115.39 (Ar
C-3), 113.43 (CN), 75.76 [C(CN)2], 55.47 (CH3O); m/z (EI) 438
(Mϩ, 42%), 390 (9), 347 (3), 272 (4), 235 (7), 215 (3), 171 (7), 153
(23), 139 (C7H7OSϩ, 100), 124 (C6H4OSϩ, 16), 96 (16), 70 (5)
(Found: Mϩ, 438.0292. C20H14N4O2S3 requires M, 438.0292).
Attempted crystallisation of the title compound from aqueous
ethanol gave a precipitate of 3,5-bis(4-methoxyphenylthio)-4H-
1,2,6-thiadiazin-4-one 5 (78%) as orange needles, mp 150–
154 ЊC (from EtOH) (Found: C, 51.9; H, 3.2; N, 7.0. C17H14-
N2O3S3 requires C, 52.3; H, 3.6; N, 7.2%); νmax(Nujol)/cmϪ1
Bis(arylthio)thiadiazines 4. Typical procedure: to a stirred sus-
pension of (3-chloro-5-phenylthio-4H-1,2,6-thiadiazin-4-yl-
idene)propanedinitrile 3a (91 mg, 0.30 mmol) in benzene (2 ml)
at 20 ЊC, under nitrogen, thiophenol (37 µl, 0.36 mmol) was
added followed by the slow addition of Hünig’s base (63 µl,
0.36 mmol) at 20 ЊC. After 1 h no starting material remained
(TLC) and chromatograpy (light petroleum–DCM, 1:3) gave
[3,5-bis(phenylthio)-4H-1,2,6-thiadiazin-4-ylidene]propane-
dinitrile 4a (104 mg, 92%) as red-orange plates, mp 177–178 ЊC
(from cyclohexane) (Found: C, 57.0; H, 2.7; N, 14.8. C18H10-
N4S3 requires C, 57.1; H, 2.65; N, 14.8%); λmax(DCM)/nm 264
(log ε 4.12), 343 (4.10), 477 (4.12); νmax(Nujol)/cmϪ1 3059w (Ar
CH), 2206s and 2195m (CN), 1578w, 1489s, 1476s, 1465s, 1442s,
1417s, 1287s, 1177m, 1146s, 1086m, 1070s, 1024m, 1002m, 826s,
742s, 704s, 689s, 666m, 634s, 602s; δH(270 MHz; CDCl3) 7.57–
7.42 (10H, m, Ar H); δC(68 MHz; CDCl3) 147.67, 138.63,
136.41 (Ar C-2), 131.37 (Ar C-4), 130.45 (Ar C-3), 127.01 (Ar
3007w (Ar CH), 1626s (C᎐O), 1593s, 1576w, 1494s, 1467s,
᎐
1439m, 1297s, 1250s, 1177m, 1068m, 1034m, 1024m, 821s, 747s;
δH(270 MHz; CDCl3) 7.40 (4H, d, J 8.7 Hz, Ar H-2), 6.96 (4H,
d, J 8.9 Hz, Ar H-3), 3.84 (6H, s, CH3O); δC(68 MHz; CDCl3)
161.78, 160.94, 160.13, 137.91 (Ar C-2), 117.69 (Ar C-1), 115.88
(Ar C-3), 56.10 (CH3O); m/z (EI) 390 (Mϩ, 97%), 251
(Mϩ Ϫ C7H7OS, 10), 197 (C8H7NOS2ϩ, 7), 165 (C8H7NOSϩ, 8),
139 (C7H7OSϩ, 100), 121 (17), 103 (16), 96 (20), 77 (C6H5ϩ, 20).
Reaction of (3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile 1 with secondary amines
Monoaminothiadiazines 6. (See Table 2) Typical procedure:
to a stirred solution of (3,5-dichloro-4H-1,2,6-thiadiazin-4-
ylidene)propanedinitrile 1 (230 mg, 1 mmol) at Ϫ5 ЊC, pyrrol-
idine (167 µl, 2 mmol) was added slowly. The mixture became
deep red and was allowed to warm to ca. 20 ЊC. Chromato-
J. Chem. Soc., Perkin Trans. 1, 2000, 1081–1088
1085

View Article Online
graphy (light petroleum–DCM, 1:3) gave (3-chloro-5-pyrrol-
idino-4H-1,2,6-thiadiazin-4-ylidene)propanedinitrile 6a (204 mg,
77%) as red crystals, mp 143–144 ЊC (from cyclohexane)
(Found: C, 45.6; H, 2.8; N, 26.2. C10H8ClN5S requires C, 45.3;
H, 3.0; N, 26.4%); λmax(DCM)/nm 248 (log ε 3.87), 330 (3.96),
520 (4.07); νmax(Nujol)/cmϪ1 2214s (CN), 1526s, 1495s, 1475s,
1455s, 1390m, 1378m, 1344m, 1332m, 1275m, 1249m, 1152m,
936m, 815s, 720s, 661m, 629m, 615m; δH(270 MHz; CDCl3)
3.71–3.48 (4H, br s, CH2N), 2.09–2.03 (4H, br s, CH2); δC(68
MHz; CDCl3) 145.70, 136.02, 131.85, 114.51 (CN), 113.30
(CN), 75.17 [C(CN)2], 50.63 (CH2N), 26.03 (CH2); m/z (EI) 265
(Mϩ, 39%), 238 (Mϩ Ϫ CHN, 12), 225 (Mϩ Ϫ C3H4, 6), 210
(Mϩ Ϫ C4H7, 21), 203 (Mϩ Ϫ CHClN, 53), 185 (15), 176
(Mϩ Ϫ C4H6Cl, 32), 169 (9), 161 (Mϩ Ϫ C4H7ClN, 31), 149
(Mϩ Ϫ C5H7ClN, 33), 144 (13), 134 (8), 129 (C5H9N2Sϩ, 6), 108
(C4N2Sϩ, 9), 95 (C5H7N2ϩ, 36), 70 (C4H8Nϩ, 100), 68 (35), 46
(NSϩ, 35).
(from cyclohexane) (Found: C, 52.05; H, 2.7; N, 23.1.
C13H8ClN5S requires C, 51.8; H, 2.7; N, 23.3%); λmax(DCM)/nm
267 (log ε 4.04), 348 (4.10), 505 (3.96); νmax(Nujol)/cmϪ1 3065w
(Ar CH), 2225s (CN), 1596m and 1586m (C᎐N) or (C᎐C),
᎐
᎐
1521s, 1489s, 1465s, 1411s, 1379s, 1317m, 1294s, 1156m, 1134s,
1084s, 1049s, 1026m, 919m, 838w, 812s, 776s, 758m, 724s, 702s,
621s, 601s; δH(270 MHz; CDCl3) 7.46–7.11 (5H, m, Ar H), 3.49
(3H, s, CH3N); δC(100 MHz; CD2Cl2) 145.25, 143.99, 138.15,
133.78, 129.72 (Ar CH), 127.34 (Ar CH), 123.97 (Ar CH),
113.06 (CN), 112.50 (CN), 77.26 [C(CN)2], 40.77 (CH3N); m/z
(EI) 301 (Mϩ, 30%), 275 (Mϩ Ϫ CN, 10), 266 (Mϩ Ϫ Cl, 25),
239 (Mϩ Ϫ CHClN, 47), 234 (21), 105 (C7H7Nϩ, 35), 91 (C6H5-
Nϩ, 13), 77 (C6H5ϩ, 100).
[3-Chloro-5-(di-n-propylamino)-4H-1,2,6-thiadiazin-4-
ylidene]propanedinitrile 6f. Red crystals (74%), mp 70–71.5 ЊC
(from EtOH–water) (Found: C, 49.1; H, 4.55; N, 23.5.
C12H14ClN5S requires C, 48.8; H, 4.75; N, 23.7%); λmax(DCM)/
nm 252 (log ε 3.82), 335 (3.96), 522 (4.00); νmax(Nujol)/cmϪ1
2209s (CN), 1520s, 1484s, 1462s, 1445s, 1430s, 1367s, 1326s,
1311s, 1296s, 1286s, 1239s, 1195s, 1163m, 1140s, 1107s, 1091s,
1042m, 1020m, 946s, 911m, 858m, 824s, 805s, 754m, 746m,
734s, 627m, 606s; δH(270 MHz; CDCl3) 3.68–3.60 (2H, br s,
CH2N), 3.29–3.23 (2H, br s, CH2N), 1.66–1.57 (4H, m, CH2),
0.87 (6H, t, J 7.3 Hz, CH3); δC(68 MHz; CDCl3) 146.67, 136.21,
132.78, 113.70 (CN), 113.09 (CN), 76.03 [C(CN)2], 52.67
(CH2N), 21.52 (CH2), 12.24 (CH3); m/z (EI) 295 (Mϩ, 14%), 266
(Mϩ Ϫ C2H5, 27), 252 (Mϩ Ϫ C3H7, 3), 224 (26), 211 (5), 205
(Mϩ Ϫ C3H5ClN, 11), 197 (8), 188 (6), 163 (16), 134 (3), 129 (3),
100 (C6H14Nϩ, 3), 70 (6), 58 (C3H8Nϩ, 10), 43 (C3H7ϩ, 100).
(3-Chloro-5-diisopropylamino-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile 6g. Lustrous metallic red crystals (30%), mp
123–125 ЊC (from cyclohexane) (Found: C, 49.1; H, 4.5; N, 23.5.
C12H14ClN5S requires C, 48.8; H, 4.75; N, 23.7%); λmax(DCM)/
nm 252 (log ε 3.83), 337 (3.96), 526 (4.00); νmax(Nujol)/cmϪ1
Similar treatment of 1 with the appropriate amine gave the
following compounds:
(3-Chloro-5-piperidino-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile 6b. Red crystals (81%), mp 134–135 ЊC (from
cyclohexane) (Found: C, 47.3; H, 3.8; N, 24.9. C11H10ClN5S
requires C, 47.3; H, 3.6; N, 25.1%); λmax(DCM)/nm 252 (log ε
3.92), 333 (4.03), 510 (4.00); νmax(Nujol)/cmϪ1 2212s (CN),
1500s (C᎐C), 1484s, 1440s, 1388s, 1367s, 1354s, 1326m, 1295s,
᎐
1277s, 1258s, 1243s, 1215s, 1166m, 1150s, 1132s, 1115m, 1075m,
1050s, 1029s, 989m, 935s, 913s, 864s, 857m, 833s, 824s, 803m,
762s, 738s, 636s, 626s, 604s; δH(270 MHz; CDCl3) 3.50–3.36
(4H, br d, CH2N), 1.79–1.75 (6H, br s, CH2); δC(68 MHz;
CDCl3) 148.25, 135.17, 134.38, 113.91 (CN), 113.30 (CN),
75.41 [C(CN)2], 49.93 (CH2N), 25.49 (CH2), 24.59 (CH2); m/z
(EI) 279 (Mϩ, 73%), 253 (Mϩ Ϫ CN, 15), 244 (Mϩ Ϫ Cl, 4), 239
(Mϩ Ϫ C3H4, 27), 225 (Mϩ Ϫ C4H6, 19), 217 (26), 169 (Mϩ Ϫ
C6H10N2, 23), 134 (Mϩ Ϫ C6H10ClN2, 11), 109 (C6H9N2ϩ, 24),
84 (C5H10Nϩ, 91).
2218s (CN), 1526s (C᎐C), 1494s, 1446s, 1406m, 1372s, 1359s,
᎐
(3-Chloro-5-morpholino-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile 6c. Red crystals (83%), mp 169–171 ЊC (from
cyclohexane) (Found: C, 42.9; H, 2.7; N, 24.7. C10H8ClN5OS
requires C, 42.7; H, 2.85; N, 24.9%); λmax(DCM)/nm 251 (log
ε 3.88), 332 (3.99), 490 (4.04); νmax(Nujol)/cmϪ1 2216s (CN),
1317m, 1258s, 1197m, 1170m, 1148s, 1126s, 1048s, 926s, 871m,
820m, 806s, 710s, 633s, 617m, 601m; δH(270 MHz; CDCl3) 3.98–
3.91 (1H, br, CHN), 1.78–1.36 (6H, br, CH3); δC(68 MHz;
CDCl3) 144.24, 137.18, 131.02, 113.31 (CN), 112.87 (CN),
76.55 [C(CN)2], 51.38 (CHN), 21.81 (CH3); m/z (EI) 295 (Mϩ,
6%), 280 (Mϩ Ϫ CH3, 1), 253 (Mϩ Ϫ C3H6, 8), 238 (Mϩ Ϫ
C4H9, 24), 211 (Mϩ Ϫ C6H12, 23), 177 (Mϩ Ϫ C5H9ClN, 36), 58
(C3H8Nϩ, 9), 43 (C3H7ϩ, 100).
1510s (C᎐C), 1484s, 1459s, 1447s, 1396s, 1378m, 1362m, 1332m,
᎐
1312m, 1286s, 1265s, 1233s, 1149m, 1115s, 1063m, 999m, 937m,
929s, 868s, 821s, 772m, 736s, 645s, 632m, 606m; δH(270 MHz;
CDCl3) 3.96–3.89 (4H, br s, CH2O), 3.55–3.51 (2H, br s,
CH2N), 3.29–3.26 (2H, br s, CH2N); δC(68 MHz; CDCl3)
148.56, 135.31, 134.61, 114.09 (CN), 113.05 (CN), 76.39
[C(CN)2], 66.10 (CH2O), 48.94 (CH2N); m/z (EI) 281 (Mϩ,
79%), 255 (Mϩ Ϫ CN, 8), 246 (Mϩ Ϫ Cl, 4), 224 (Mϩ Ϫ C3H5O,
30), 220 (16), 216 (14), 211 (21), 205 (8), 196 (Mϩ Ϫ C4H7NO,
41), 169 (Mϩ Ϫ C5H8N2O, 51), 162 (46), 135 (25), 129 (14), 116
(9), 111 (C5H7N2Oϩ, 16), 108 (C4N2Sϩ, 17), 86 (C4H8NOϩ, 33),
56 (C3H4Oϩ, 100).
(3-Chloro-5-dibenzylamino-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile 6d. Red needles (74%), mp 166–167 ЊC (from
cyclohexane) (Found: C, 61.4; H, 3.6; N, 17.7. C20H14ClN5S
requires C, 61.4; H, 3.6; N, 17.9%); λmax(DCM)/nm 252 (log ε
3.96), 333 (3.95), 502 (4.03); νmax(Nujol)/cmϪ1 3085w, 3058w
Bisaminothiadiazines 7. (See Table 2) Typical procedure: to a
stirred solution of (3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile 1 (230 mg, 1 mmol) at Ϫ5 ЊC, pyrrolidine (334
µl, 4 mmol) was added slowly. The mixture became red then
blue and was allowed to warm to ca. 20 ЊC. After 12 h only
the product was present (TLC) and chromatography (light
petroleum–DCM, 1:3) gave (3,5-dipyrrolidino-4H-1,2,6-thia-
diazin-4-ylidene)propanedinitrile 7a (252 mg, 84%) as blue
crystals, mp 190 ЊC (subl.) (from cyclohexane) (Found: C, 56.2;
H, 5.1; N, 27.7. C14H16N6S requires C, 56.0; H, 5.3; N, 28.0%);
λmax(DCM)/nm 229 (log ε 4.28), 323 (4.15), 591 (4.03);
νmax(Nujol)/cmϪ1 2215s (CN), 1538s, 1500s, 1456s, 1397s,
1378m, 1343s, 1324s, 1299m, 1251m, 1224m, 1188m, 1175m,
1152m, 1108m, 918m, 860m, 837m, 805m, 734s, 681s, 626m,
615m, 595s; δH(270 MHz; CDCl3) 3.67–3.32 (8H, br s, CH2N),
2.00 (8H, br s, CH2); δC(68 MHz; CDCl3) 146.76, 133.03, 115.44
(CN), 70.75 [C(CN)2], 49.80 (br s, CH2N), 25.92 (CH2); m/z (EI)
300 (Mϩ, 48%), 274 (Mϩ Ϫ CN, 9), 203 (Mϩ Ϫ C5H9N2, 8), 200
(16), 161 (2), 149 (2), 129 (4), 116 (3), 103 (6), 95 (6), 70
(C4H8Nϩ, 100), 68 (24).
and 3028w (Ar CH), 2212s (CN), 1603w and 1585w (C᎐N) or
᎐
(C᎐C), 1498s, 1481s, 1455s, 1429s, 1391m, 1353s, 1329m,
᎐
1148m, 1131m, 1054m, 934m, 831m, 812m, 802m, 761m, 737s,
702m, 696m, 638m, 603m; δH(270 MHz; CDCl3) 7.39–7.31 (6H,
m, Ar H), 7.16–7.12 (4H, m, Ar H), 4.67–4.63 (2H, br s,
CH2N), 4.54–4.52 (2H, br s, CH2N); δC(68 MHz; CDCl3)
147.35, 135.87, 135.42, 134.36, 129.80 (Ar CH), 129.42 (Ar
CH), 129.17 (Ar CH), 114.04 (CN), 113.03 (CN), 76.66
[C(CN)2], 54.76 (CH2N); m/z (EI) 391 (Mϩ, 0.5%), 330
(Mϩ Ϫ CClN, 1), 300 (Mϩ Ϫ C7H7, 1.5), 274 (Mϩ Ϫ C8H7N,
0.5), 91 (C7H7ϩ, 100).
Similar treatment of 1 with the appropriate amine gave the
following compounds:
(3,5-Dipiperidino-4H-1,2,6-thiadiazin-4-ylidene)propane-
dinitrile 7b. Blue crystals (78%), mp 149–150 ЊC (from cyclo-
hexane) (Found: C, 58.8; H, 5.9; N, 25.4. C16H20N6S requires C,
58.5; H, 6.1; N, 25.6%); λmax(DCM)/nm 236 (log ε 4.20), 331
[3-Chloro-5-(N-methylanilino)-4H-1,2,6-thiadiazin-4-yl-
idene]propanedinitrile 6e. Red crystals (85%), mp 126–127 ЊC
1086
J. Chem. Soc., Perkin Trans. 1, 2000, 1081–1088

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(4.10), 567 (3.94); νmax(Nujol)/cmϪ1 2213s (CN), 1515s (C᎐C),
(br s, CH2N), 21.44 (CH2), 12.25 (CH3); m/z (EI) 360 (Mϩ,
᎐
1499s, 1474s, 1455s, 1439s, 1397m, 1377m, 1365m, 1352m,
1316m, 1267m, 1220m, 1115m, 1020m, 801m, 731s, 629m;
δH(270 MHz; CDCl3) 3.51–3.48 (4H, br, CH2N), 3.13–3.10
(4H, br, CH2N), 1.79–1.65 (12H, br d, CH2); δC(68 MHz;
CDCl3) 150.30, 132.78, 115.10 (CN), 70.93 [C(CN)2], 49.57
(CH2N), 25.34 (CH2), 24.95 (CH2); m/z (EI) 328 (Mϩ, 93%), 302
(Mϩ Ϫ CN, 12), 274 (Mϩ Ϫ C4H6, 4), 259 (Mϩ Ϫ C5H9, 5), 252
(4), 245 (Mϩ Ϫ C5H9N, 5), 217 (Mϩ Ϫ C6H11N2, 10), 214 (12),
129 (8), 116 (6), 109 (C6H9N2ϩ, 3), 84 (C5H10Nϩ, 100), 69
(C5H9ϩ, 12).
86%), 331 (Mϩ Ϫ C2H5, 40), 317 (Mϩ Ϫ C3H7, 51), 289 (5), 275
(Mϩ Ϫ C6H13, 12), 262 (Mϩ Ϫ C6H12N, 33), 205 (18), 149 (15),
100 (C6H14Nϩ, 100), 70 (19), 58 (C3H8Nϩ, 33), 43 (C3H7ϩ, 94).
N-(4-Anilino-5-cyano-7-phenyl-6H-pyrrolo[2,3-c][1,2,6]-
thiadiazin-6-ylidene)aniline 8
To a stirred solution of (3,5-dichloro-4H-1,2,6-thiadiazin-4-
ylidene)propanedinitrile 1 (115 mg, 0.5 mmol) in DCM (15 ml)
at ca. 20 ЊC, aniline (169 µl, 2 mmol) was added. The mixture
was complex (TLC). Refluxing at 50 ЊC for 12 h gave a deep red
product, and on cooling to ca. 20 ЊC the volatiles were removed.
Chromatography (DCM) gave the title compound 8 (11 mg, 5%)
as red needles, mp 220–225 ЊC (from EtOH); δH(270 MHz;
CDCl3) 8.03–6.97 (15H, m, Ar H), 5.70–5.60 (1H, br, NH);
δH(270 MHz; CDCl3, D2O exchanged) 8.03–6.97 (15H, m, Ar
H); δC(68 MHz; CDCl3) 150.73, 150.71, 149.28, 145.13, 138.06,
133.54, 130.14 (Ar CH), 130.00 (Ar CH), 129.74 (Ar CH),
129.62 (Ar CH), 128.61 (Ar CH), 125.70 (Ar CH), 125.59 (Ar
CH), 125.52 (Ar CH), 122.65 (Ar CH), 121.44, 119.16, 115.62
(CN); m/z (EI) 420 (Mϩ, 100%), 404 (Mϩ Ϫ H2N, 10), 374
(Mϩ Ϫ NS, 7), 343 (Mϩ Ϫ C6H5, 6), 317 (Mϩ Ϫ C7H5N, 4), 301
(7), 267 (6), 236 (3), 210 (Mϩϩ, 7), 194 (5), 162 (11), 132 (3), 113
(7), 103 (C7H5Nϩ, 5), 77 (C6H5ϩ, 34) (Found: Mϩ, 420.1155.
C24H16N6S requires M, 420.1157).
(3,5-Dimorpholino-4H-1,2,6-thiadiazin-4-ylidene)propane-
dinitrile 7c. Blue crystals (76%), mp 190 ЊC (subl.) (from cyclo-
hexane) (Found: C, 50.7; H, 4.6; N, 25.0. C14H16N6O2S requires
C, 50.6; H, 4.8; N, 25.3%); λmax(DCM)/nm 229 (log ε 4.21), 329
(4.10), 543 (4.03); νmax(Nujol)/cmϪ1 2207s (CN), 1509s (C᎐C),
᎐
1471s, 1444s, 1433s, 1395s, 1379s, 1368m, 1351s, 1331m, 1307m,
1286m, 1265s, 1252s, 1200m, 1171m, 1115s, 1067m, 1056m,
1015m, 1006m, 991m, 906m, 866m, 852m, 804m, 744s, 675m,
667m, 650m, 631m, 618m, 594m; δH(270 MHz; CDCl3) 3.90
(8H, br s, CH2O), 3.53–3.38 (4H, br s, CH2N), 3.19–3.06 (4H,
br s, CH2N); δC(68 MHz; CDCl3) 150.09, 130.82, 114.90 (CN),
71.69 [C(CN)2], 66.14 (CH2O), 48.60 (CH2N); m/z (EI) 332
(Mϩ, 100%), 306 (Mϩ Ϫ CN, 1), 275 (Mϩ Ϫ C3H5O, 3), 247
(Mϩ Ϫ C4H7NO, 4), 214 (Mϩ Ϫ C4H8NOS, 15), 189 (7), 161 (5),
157 (5), 135 (5), 129 (11), 116 (5), 108 (2), 104 (4), 86
(C4H8NOϩ, 68), 56 (C3H4Oϩ, 46).
[3,5-Bis(dibenzylamino)-4H-1,2,6-thiadiazin-4-ylidene]-
propanedinitrile 7d. Blue crystals (81%), mp 190–191 ЊC (from
cyclohexane) (Found: C, 73.8; H, 5.3; N, 15.1. C34H28N6S
requires C, 73.9; H, 5.1; N, 15.2%); λmax(DCM)/nm 236 (log
ε 4.23), 338 (4.12), 565 (3.99); νmax(Nujol)/cmϪ1 3168w, 3106w,
3087m, 3060m and 3030m (Ar CH), 2210s (CN), 1604w and
(3-Chloro-5-phthalimido-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile and (3,5-diphthalimido-4H-1,2,6-thiadiazin-
4-ylidene)propanedinitrile
To a stirred solution of (3,5-dichloro-4H-1,2,6-thiadiazin-4-
ylidene)propanedinitrile 1 (125 mg, 0.54 mmol) in toluene
(3 ml) at ca. 20 ЊC was added potassium phthalimide (200 mg,
1.08 mmol) and 18-crown-6 (143 mg, 0.54 mmol). The mixture
became brown and TLC indicated several new products. The
mixture was heated to 80 ЊC for 2 h and allowed to cool to
ca. 20 ЊC. Chromatography (light petroleum–DCM, 1:1) gave
(3-chloro-5-phthalimido-4H-1,2,6-thiadiazin-4-ylidene)propane-
dinitrile (46 mg, 25%) as yellow prisms, mp > 190 ЊC (dec.)
(from 1,2-dichloroethane) (Found: C, 49.3; H, 1.3; N, 20.6.
C14H4ClN5O2S requires C, 49.3; H, 1.2; N, 20.5%); λmax(DCM)/
nm 229 (log ε 4.37), 234 inf (4.33), 246 inf (4.18), 302 (3.33), 406
(4.31); νmax(Nujol)/cmϪ1 3105w and 3070w (Ar CH), 2220s
1587w (C᎐N) or (C᎐C), 1509s, 1495s, 1477s, 1462s, 1452s,
᎐
᎐
1434s, 1397s, 1363s, 1326s, 1296m, 1237s, 1187s, 1149m, 1115m,
1077s, 1030m, 965m, 942m, 860s, 838s, 822m, 750s, 738s, 651m,
633m, 604s; δH(270 MHz; CDCl3) 7.23–7.19 (12H, m, Ar H),
7.05 (8H, m, Ar H), 4.67–4.62 (4H, br d, CH2N), 4.37–4.31
(4H, br d, CH2N); δC(68 MHz; CDCl3) 150.82, 136.28, 131.56,
129.08 (Ar CH), 129.35 (Ar CH), 128.56 (Ar CH), 115.42 (CN),
71.94 [C(CN)2], 54.11 (CH2N); m/z (EI) 552 (Mϩ, 3%), 461
(Mϩ Ϫ C7H7, 3), 369 (Mϩ Ϫ C14H15, 2), 196 (3), 154 (10), 127
(11), 91 (C7H7ϩ, 100).
[3,5-Bis(N-methylanilino)-4H-1,2,6-thiadiazin-4-ylidene]-
propanedinitrile 7e. Blue crystals (87%), mp 176–177 ЊC (from
cyclohexane) (Found: C, 64.4; H, 4.35; N, 22.4. C20H16N6S
requires C, 64.5; H, 4.3; N, 22.6%); λmax(DCM)/nm 257 (log
ε 4.16), 268 (4.17), 360 (4.04), 554 (3.90); νmax(Nujol)/cmϪ1
3100w, 3060w and 3017m (Ar CH), 2209s (CN), 1595s and
1585m (C᎐N) or (C᎐C), 1505s (C᎐C), 1478s, 1451s, 1412s,
1402s, 1380s, 1353s, 1330m, 1310m, 1293m, 1267m, 1212s,
1174m, 1148m, 1135s, 1120m, 1102s, 1047s, 1022m, 892m,
843m, 787m, 766s, 745s, 700s, 659m, 633s, 620m; δH(270 MHz;
CDCl3) 7.33–7.14 (10H, m, Ar H), 3.35 (6H, s, CH3N); δC(68
MHz; CDCl3) 149.64, 145.07, 139.03, 130.07 (Ar CH), 127.10
(Ar CH), 124.71 (Ar CH), 114.85 (CN), 73.77 [C(CN)2], 41.17
(CH3N); m/z (EI) 372 (Mϩ, 74%), 265 (Mϩ Ϫ C7H9N, 7), 234
(Mϩ Ϫ C7H8NS, 23), 106 (C7H8Nϩ, 7), 91 (C6H5Nϩ, 18), 77
(C6H5ϩ, 100).
[3,5-Bis(di-n-propylamino)-4H-1,2,6-thiadiazin-4-ylidene]-
propanedinitrile 7f. Blue crystals (82%), mp 84–87 ЊC (from
EtOH–water) (Found: C, 59.9; H, 7.8; N, 23.0. C18H28N6S
requires C, 60.0; H, 7.8; N, 23.3%); λmax(DCM)/nm 236 (log
ε 4.21), 333 (4.13), 586 (3.99); νmax(Nujol)/cmϪ1 2204s (CN),
1489s, 1451s, 1431s, 1395s, 1383s, 1367s, 1354s, 1342s, 1325m,
1306m, 1272m, 1249m, 1215m, 1189m, 1156s, 1076s, 901m,
862m, 835m, 748s, 634m, 616m; δH(270 MHz; CDCl3) 3.59–
3.50 (4H, br s, CH2N), 3.16–3.11 (4H, br s, CH2N), 1.75–1.46
(8H, br m, CH2), 1.05–0.86 (12H, t, J 7.3 Hz, CH3); δC(68 MHz;
CDCl3) 149.37, 133.68, 115.10 (CN), 71.18 [C(CN)2], 52.26
(CN), 1797s and 1735s (C᎐O), 1611w, 1520s (C᎐C), 1481s,
᎐ ᎐
1471s, 1372s, 1303s, 1220s, 1179m, 1153s, 1096m, 1066s, 909s,
882s, 810s, 788s, 739s, 723s, 713s, 647s, 629m; δH(270 MHz;
CDCl3) 8.05–7.99 (2H, m, Ar H), 7.91–7.86 (2H, m, Ar H);
δ (68 MHz; CDCl ) 164.39 (C᎐O), 144.49, 138.20, 136.70,
᎐
C
3
136.53 (Ar CH), 131.81, 125.98 (Ar CH), 113.02 (CN), 112.67
(CN), 79.17 [C(CN)2]; m/z (EI) 341 (Mϩ, 7%), 315 (Mϩ Ϫ CN,
3), 306 (Mϩ Ϫ Cl, 3), 280 (Mϩ Ϫ CClN, 59), 236 (24), 178 (10),
160 (12), 147 (6), 128 (7), 104 (C7H4Oϩ, 100), 76 (C6H4ϩ, 100),
50 (62), 46 (NSϩ, 18).
Further elution (light petroleum–DCM, 1:1) gave (3,5-
diphthalimido-4H-1,2,6-thiadiazin-4-ylidene)propanedinitrile
(49 mg, 20%) as yellow prisms, mp 275 ЊC (dec.) (from 1,2-
dichloroethane) (Found: C, 58.3; H, 2.05; N, 18.6. C22H8N6O4S
requires C, 58.4; H, 1.8; N, 18.6%); λmax(DCM)/nm 229 (log
ε 4.63), 235 inf (4.59), 246 inf (4.47), 297 (3.76), 306 (3.74), 408
(4.29); νmax(Nujol)/cmϪ1 3095w and 3043w (Ar CH), 2218s
᎐
᎐
᎐
(CN), 1790s and 1741s (C᎐O), 1608m, 1515s (C᎐C), 1485s,
᎐
᎐
1467s, 1353s, 1304s, 1235m, 1205m, 1177m, 1155m, 1133m,
1101m, 1079s, 1063s, 984m, 969s, 885s, 851m, 807m, 787m,
740s, 712s, 668m, 628s; δH(270 MHz; DMSO-d6) 8.17–8.14 (4H,
m, Ar H), 8.06–8.03 (4H, m, Ar H); m/z (EI) 452 (Mϩ, 26%),
426 (Mϩ Ϫ CN, 3), 410 (Mϩ Ϫ CNO, 3), 280 (21), 274 (5), 252
(2), 236 (5), 178 (4), 160 (2), 147 (25), 130 (21), 104 (C7H4Oϩ,
93), 76 (C6H4ϩ, 100).
A final elution (light petroleum–acetone, 3:1) gave an
unknown purple solid (16 mg, 10%), mp 140–150 ЊC (from 1,2-
J. Chem. Soc., Perkin Trans. 1, 2000, 1081–1088
1087

View Article Online
dichloroethane–pentane) (Found: C, 47.0; H, 6.3; N, 11.5%)
νmax(Nujol)/cmϪ1 2163s (CN), 1626w, 1604m, 1511w, 1467s,
1377m, 1349s, 1284m, 1248m, 1233m, 1133m, 1106s, 962s,
838m, 722w; m/z (FAB) 303 (Mϩ or MHϩ, 100%).
N, 20.7. C8H6N4O2S2 requires C, 37.8; H, 2.4; N, 22.0%);
νmax(Nujol)/cmϪ1 3300br (OH), 2213s (CN), 1607s, 1576s,
1523m, 1500s, 1427m, 1318s, 1225s, 1198m, 1100w, 1048m,
1009m, 991m, 917m, 860s, 768s, 760s, 705m, 638m; m/z (EI) 254
(Mϩ, 7%), 239 (Mϩ Ϫ CH3, 11), 221 (Mϩ Ϫ HS, 7), 208
(Mϩ Ϫ NS or CH2S, 14), 194 (11), 177 (19) (Found: Mϩ,
253.9939. C8H6N4O2S2 requires M, 253.9932); LSMS (EI, B/E
of m/z 254) 239 (Mϩ Ϫ CH3, 100%), 223 (34), 208 (36), 194 (13),
177 (4), 169 (7). The filtrate was extracted with DCM (5 × 5 ml)
and the combined DCM fractions were dried, filtered and the
volatiles were removed. Chromatography (DCM) of the residue
gave 4-chloro-5-cyano-6-methylthioimino-6H-furo[2,3-c][1,2,6]-
thiadiazine 10 (27 mg, 5%) as deep red plates, mp > 280 ЊC
(from 1,2-dichloroethane–cyclohexane) (Found: C, 32.5; H, 1.1;
N, 21.5. C7H3ClN4OS2 requires C, 32.6; H, 1.2; N, 21.7%);
λmax(DCM)/nm 257 (log ε 3.88), 359 (4.21), 488 (4.20);
νmax(Nujol)/cmϪ1 2233m (CN), 1636w, 1577s, 1473s, 1376s,
1291m, 1181m, 995s, 919s, 810m, 799m, 761m, 724m, 667m,
608m; δH(500 MHz; CD2Cl2) 2.84 (3H, s, CH3S); δC(100 MHz;
(3,5-Dimorpholino-1-oxo-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile 9
Method 1. To a stirred solution of (3,5-dimorpholino-4H-
1,2,6-thiadiazin-4-ylidene)propanedinitrile 7c (90 mg, 0.27
mmol) in DCM (15 ml) was introduced gaseous N2O4. The deep
purple mixture rapidly became orange and the passage of N2O4
was stopped. TLC indicated no starting thiadiazine but showed
a new orange product. Chromatography (ethyl acetate) gave the
title compound 9 (89 mg, 95%) as orange needles, mp > 300 ЊC
(from THF) (Found: C, 48.5; H, 4.75; N, 24.2. C14H16N6O3S
requires C, 48.3; H, 4.6; N, 24.1%); λmax(DCM)/nm 261 (log
ε 4.25), 315 (3.02), 454 (3.24); νmax(Nujol)/cmϪ1 2240w (CN),
1577s, 1533s, 1455s, 1363m, 1302m, 1276s, 1256m, 1215m,
1129s, 1112s, 1068m, 1053m, 1003m, 903m, 861m, 851m, 806m,
777s, 757s, 643s; δH(270 MHz; DMSO-d6) 3.86–3.66 [10H, m,
4(CH2O)ϩ1(CH2N)], 3.59–3.48 (2H, m, CH2N), 3.40–3.17 [4H,
m, 2(CH2N)]; δC(68 MHz; DMSO-d6) 152.32, 144.97, 111.50
(CN), 90.05 [C(CN)2], 66.06 (CH2O), 65.71 (CH2O), 48.37
(CH2N), 45.56 (CH2N); m/z (EI) 348 (Mϩ, 3%), 332 (Mϩ Ϫ O,
30), 300 (Mϩ Ϫ OS, 4), 243 (3), 214 (5), 189 (3), 162 (6), 135 (4),
129 (6), 112 (C5H8N2Oϩ, 16), 103 (5), 86 (C4H8NOϩ, 39), 77 (7),
70 (9), 55 (75), 42 (83).
CD Cl ) 158.21 (C᎐NSMe), 144.69, 141.44, 124.51, 110.46
᎐
2
2
(CN), 96.16 [᎐C(CN)], 24.39 (CH S); m/z (EI) 258 (Mϩ, 100%),
᎐
3
243 (Mϩ Ϫ CH3, 29), 212 (Mϩ Ϫ CH2S, 37), 185 (Mϩ Ϫ
C2H3NS, 6), 47 (CH3Sϩ, 28), 46 (NSϩ, 16) (Found: Mϩ,
257.9435. C7H3ClN4OS2 requires M, 257.9437); LSMS (EI, B/E
of m/z 258) 243 (Mϩ Ϫ CH3, 100%), 212 (Mϩ Ϫ CH2S, 95), 195
(Mϩ Ϫ CH3NS, 2), 185 (Mϩ Ϫ C2H3NS, 6), 177 (4), 169 (7).
Further elution (DCM) gave 4-chloro-5-cyano-6-oxo-6H-furo-
[2,3-c][1,2,6]thiadiazine 11 (112 mg, 25%) as yellow needles,
mp 109–113Њ C (from cyclohexane) (Found: C, 33.8; N, 19.5.
C6ClN3O2S requires C, 33.8; N, 19.7%); λmax(DCM)/nm 323 inf
(log ε 3.38), 398 inf (4.41), 407 (4.45), 431 (4.27); νmax(Nujol)/
Method 2. To a stirred solution of (3,5-dimorpholino-4H-
1,2,6-thiadiazin-4-ylidene)propanedinitrile 7c (10 mg, 0.03
mmol) in DCM (5 ml) at 20 ЊC, MCPBA (1.1 equiv.) was added
in one portion. After 10 min the mixture still contained starting
material (TLC); however, the introduction of a further portion
of MCPBA (0.5 equiv.) resulted in the complete consumption
of the starting material within 30 min. Chromatography (ethyl
acetate) gave the title compound 9 (8.9 mg, 85%) as orange
needles, identical to that described above.
cmϪ1 2230s (CN), 1816s (C᎐O), 1634w, 1595s, 1568s, 1523w,
᎐
1452s, 1385s, 1354m, 1317m, 1304s, 1160s, 1035m, 950m, 939m,
921s, 816m, 771m, 722s, 708m, 638s; δC(68 MHz; CDCl3)
159.58 (C᎐O), 156.05, 143.67, 130.68, 110.51 (CN), 88.81
᎐
[᎐C(CN)]; m/z (EI) 213 (Mϩ, 100%), 185 (Mϩ Ϫ CO, 23), 167
᎐
(Mϩ Ϫ NS, 19), 157 [Mϩ Ϫ 2(CO), 7], 139 (Mϩ Ϫ CNOS, 9),
132 (14), 96 (8), 74 (CNOSϩ, 22) (Found: Mϩ, 212.9405.
C6ClN3O2S requires M, 212.9400).
Reaction of sulfoxide 9 with triphenylphosphine–tetrachloro-
methane
Acknowledgements
To a stirred solution of (3,5-dimorpholino-1-oxo-4H-1,2,6-
thiadiazin-4-ylidene)propanedinitrile 9 (8.4 mg, 0.024 mmol) in
DCM (5 ml) at 20 ЊC, triphenylphosphine (7 mg, 0.027 mmol)
and tetrachloromethane (0.2 ml) were added. The mixture was
taken to reflux (ca. 45 ЊC) and after 2 h no triphenylphosphine
remained (TLC); however, both the reduced product and start-
ing sulfoxide were present. The addition of more triphenyl-
phosphine (3.2 mg, 0.012 mmol), after 30 min warming,
resulted in the complete consumption of the starting material.
Chromatography (DCM–ether, 1:1) gave (3,5-dimorpholino-
4H-1,2,6-thiadiazin-4-ylidene)propanedinitrile 7c (7.3 mg, 92%)
as a purple solid, identical to that described above. Further
elution (ethyl acetate) gave triphenylphosphine oxide (6.3 mg,
94%), identical to an authentic sample. The experiment was
repeated with the exclusion of tetrachloromethane and on
reflux (ca. 45 ЊC) no reaction was observed until a little
tetrachloromethane was added.
We thank the EPSRC for a Research Studentship (P. A. K),
Professor D. J. Williams for X-ray crystallography, Mr R.
Sheppard for expert help with NMR spectroscopy, MDL
Information Sytems (UK) Ltd for financial support and the
Wolfson Foundation for establishing the Wolfson Centre for
Organic Chemistry in Medical Science at Imperial College.
References
1 P. A. Koutentis, C. W. Rees, A. J. P. White and D. J. Williams, Chem.
Commun., 2000, 303.
2 J. Geevers and W. P. Trompen, Recl. Trav. Chim. Pays-Bas, 1974, 93,
270.
3 P. A. Koutentis and C. W. Rees, unpublished work.
4 M. S. Gibson and R. W. Bradshaw, Angew. Chem., Int. Ed. Engl.,
1968, 7, 919.
5 T. Breining, A. R. Cimpoia, T. S. Mansour, N. Cammack, P.
Hopewell and C. Ashman, Heterocycles, 1995, 41, 87.
6 L. H. McKendry and W. P. Bland, USP 4 155 746/1979 (Chem.
Abstr., 1980, 91, 103730).
Reaction of (3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)-
propanedinitrile 1 with DMSO
7 R. Wigand and J. M. Guerra, J. Photochem. Photobiol. A: Chem.,
1995, 88, 35.
8 J. P. A. Castrillón and H. H. Szmant, J. Org. Chem., 1965, 30, 1338.
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43, 4503.
10 R. A. Amos, J. Org. Chem., 1985, 50, 1311.
11 D. J. Williams, unpublished work.
12 S. Patai, Z. Rappoport and C. J. M. Stirling, The Chemistry of
Sulfones and Sulfoxides, Wiley, Chichester, 1988.
(See Scheme 5)
A solution of (3,5-dichloro-4H-1,2,6-
thiadiazin-4-ylidene)propanedinitrile 1 (483 mg, 2.1 mmol) in
DMSO (2 ml) was stirred for 3 h. The mixture became red and
TLC indicated the presence of several new products. Dilution
of the mixture with water (20 ml) gave a dark grey precipitate
and filtration of this gave 5-cyano-4-hydroxy-6-methylthio-
methylimino-6H-furo[2,3-c][1,2,6]thiadiazine 12 (32 mg, 6%) as
a green-brown precipitate, mp > 280 ЊC (Found: C, 37.3; H, 2.4;
Paper b000964o
1088
J. Chem. Soc., Perkin Trans. 1, 2000, 1081–1088