Substitution at C-4 in 3,5-disubstituted 4H-1,2,6-thiadiazin-4-ones

Article abstract of DOI:10.1016/j.tet.2012.01.098

3,5-Diaryl-4H-1,2,6-thiadiazin-4-ones react with NaBH₄ to give the 3,5-diaryl-4H-1,2,6-thiadiazin-4-ols and with MeLi to give 4-methyl-3,5-diaryl-4H-1,2,6-thiadiazin-4-ols. The latter dehydrate with p-toluenesulfonic acid to give (3,5-diarylthi

Full text of DOI:10.1016/j.tet.2012.01.098

Tetrahedron 68 (2012) 2590e2597
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Substitution at C-4 in 3,5-disubstituted 4H-1,2,6-thiadiazin-4-ones
*
Heraklidia A. Ioannidou, Panayiotis A. Koutentis
Department of Chemistry, University of Cyprus, PO Box 20537, 1678 Nicosia, Cyprus
a r t i c l e i n f o
a b s t r a c t
Article history:
3,5-Diaryl-4H-1,2,6-thiadiazin-4-ones react with NaBH4 to give the 3,5-diaryl-4H-1,2,6-thiadiazin-4-ols
and with MeLi to give 4-methyl-3,5-diaryl-4H-1,2,6-thiadiazin-4-ols. The latter dehydrate with p-tol-
uenesulfonic acid to give (3,5-diarylthiadiazin-4-ylidene)methanes. (3,5-Diphenyl-4H-1,2,6-thiadiazin-
4-ylidene)methane 15 suffers mono bromination with NBS to give bromo(3,5-diphenyl-4H-1,2,6-
thiadiazin-4-ylidene)methane 17. Dichloro- and dibromo(3,5-diphenyl-4H-1,2,6-thiadiazin-4-ylidene)
methanes 18 and 19 are formed directly from the 3,5-diphenylthiadiazin-4-one 9 via the Appel reaction
using Ph3P and CCl4 or CBr4, respectively. 3,5-Diarylthiadiazin-4-ones treated with P2S5 give 3,5-
diarylthiadiazine-4-thiones that react with tetracyanoethylene oxide to give the (thiadiazin-4-ylidene)
malononitriles. Finally, the 3,5-diphenylthiadiazine-4-thione 20 reacts with ethyl diazoacetate to give
ethyl 2-(3,5-diphenyl-4H-1,2,6-thiadiazin-4-ylidene)acetate 26. The above reactions show that a variety
of substitutions at C-4 of 3,5-diaryl substituted 1,2,6-thiadiazin-4-ones can be achieved, which extends
the potential applications of this heterocycle. All compounds are fully characterized and a brief com-
parison of their spectroscopic properties is given.
Received 21 November 2011
Received in revised form 14 January 2012
Accepted 31 January 2012
Available online 4 February 2012
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
Various oxidised 1,2,6-thiadiazines such as the sulfoxides and,
more importantly, the sulfones have received considerable attention
in various areas of applied chemistry including the pharmaceutical,1
agrochemical,2 and materials3 sectors. Commercially, an important
1,2,6-thiadiazine is bentazone [3-isopropyl-lH-2,l,3-benzothiadiazin-
4(3H)-one 2,2-dioxide], which is a selective herbicide of long-stand-
ing.4 1,2,6-Thiadiazines that are not oxidised on sulfur are rare.5,6
Scheme 1.
has not prompted extensive studies and the known chemistry of the
dichlorothiadiazines 1 and 2 remains limited. The chlorines in 1 and
2 can be successively displaced by a range of nucleophiles, the sec-
ond requiring more vigorous conditions.7,11,12,14 To the best of our
knowledge there are no reports on the direct intermolecular con-
densation on the C-4 carbonyl of the dichlorothiadiazinone 1. In our
hands, attempts to directly convert the thiadiazinone 1 into the
dicyanomethylene 2 using malononitrile failed. This could be owed
(a) to the partially negative charge of the oxygen atom, which is
stabilized by a positive charge on the sulfur atom in the resonance
forms (Scheme 2) and (b) to the preference for displacement of the
chlorine atoms at positions C-3 and C-5.
Two notable exceptions, 3,5-dichloro-4H-1,2,6-thiadiazin-4-one
(1) and its dicyanomethylene analogue 2, are potentially useful
thiadiazine building blocks.7e13 The former can be readily prepared
from dichloromalononitrile and SCl2, followed by hydrolysis with
formic acid; in good overall yield (78%)7 while the latter from tet-
racyanoethylene (TCNE) and SCl2 (Scheme 1).8,9
While many 5-substituted derivatives of 3-chloro-4H-1,2,6-
thiadiazin-4-ones have high fungicidal activity,14e17 this usefulness
* Corresponding author. Tel.: þ357 99176127; fax: þ357 22892809; e-mail address:
koutenti@ucy.ac.cy (P.A. Koutentis).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2012.01.098

H.A. Ioannidou, P.A. Koutentis / Tetrahedron 68 (2012) 2590e2597
2591
The optical/electrical properties of such oligomers or polymers
could be moderated by manipulation of the thiadiazine C-4 posi-
tion. Below we report our efforts to moderate the C-4 position of
the model compound 3,5-diphenyl-4H-1,2,6-thiadiazin-4-one (9)
together with some related chemistry of 3,5-dithien-2-yl-4H-1,2,6-
thiadiazin-4-one (10).
Scheme 2.
Nevertheless, both dichlorothiadiazine scaffolds 1 and 2 treated
with bidentate bisnucleophiles initially suffer mono chloro sub-
stitution to give intermediates that readily undergo intramolecular
cyclocondensation to give fused thiadiazines (e.g., the reactionwith 2-
aminobenzenethiol 3 to afford the thiazinothiadiazine 4, Scheme 3).11
2. Results and discussion
2.1. Addition reactions
Both 3,5-diphenyl- and 3,5-dithien-2-yl-4H-1,2,6-thiadiazin-4-
ones 9 and 10 were prepared in multigram quantities (up to 5 g)
via SuzukieMiyaura or Stille coupling reactions starting from 3,5-
dichloro-4H-1,2,6-thiadiazin-4-one (1).13 Our study on the chem-
istry of the C-4 position began with the formal addition of hydrogen
and methane across the carbonyl. The mild reduction of the
diphenylthiadiazinone 9 using NaBH4 (2 equiv) in dry MeOH gave
3,5-diphenyl-4H-1,2,6-thiadiazin-4-ol (11) in 90% yield in only
5 min, however, owing to the poor solubility of the dithienylthia-
diazinone 10 in MeOH the analogous reduction of the latter
required a 1:1 mixture of MeOH and DCM (Table 1).
Scheme 3.
Fused 4H-1,2,6-thiadiazines such as acenaphtho[5,6-cd][1,2,6]
thiadiazine (5),18,19 and naphtho[1,8-cd:4,5-c0d0]bis([1,2,6]thiadia-
zine) (6),20 have been studied as examples of ‘extreme quinoids’,
that have ambiguous aromatic character. More recently Torroba
et al., prepared cyclopenta[1,2,6]thiadiazines 7 and 8 starting from
cyclic enaminonitriles,21,22 some of which displayed unusual liquid
crystalline properties or behaved as near infra-red dyes (Scheme 4).
Table 1
Addition reactions of 3,5-diaryl-4H-1,2,6-thiadiazin-4-ones 9 and 10
R1
Conditions
Time (min)
R2
Yields (%)
Ph
NaBH4 (2 equiv), MeOH, 50 ꢀ
C
5
15
H
H
11 (97)
12 (98)
Thien-2-yl
NaBH4 (2 equiv), MeOH/DCM
(1:1), 50 ꢀ
C
Ph
MeLi (4 equiv), THF, 0e10 ꢀC
MeLi (4 equiv), THF, 0e10 ꢀC
60
60
Me
Me
13 (90)
14 (79)
Thien-2-yl
Scheme 4.
Recently, we have demonstrated that CeC coupling reactions
can be applied to 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (1) to
form both symmetrical and non-symmetrical 1,2,6-thiadiazin-4-
ones.13,23 This development in the chemistry of the dichloro-
thiadiazinone 1 could potentially lead to the construction of novel
Addition of methane could also be achieved by treating 3,5-
diphenyl- and 3,5-dithien-2-ylthiadiazinones 9 and 10 with MeLi
in dry THF at 0e10 ꢀC, to give after 1 h 4-methyl-3,5-diphenyl- and
4-methyl-3,5-dithien-2-yl-4H-1,2,6-thiadiazin-4-ols 13 and 14 in
high yields, respectively (Table 1).
Attempts to chlorodehydroxylate or prepare the triflate of 4-
methyl-3,5-diphenyl-4H-1,2,6-thiadiazin-4-ol (13), using SOCl2 or
Tf2O/Et3N, respectively, gave only the dehydrated (3,5-diphenyl-
4H-1,2,6-thiadiazin-4-ylidene)methane (15). In light of this facile
dehydration the diphenyl- and dithienylthiadiazinols 13 and 14
were treated with catalytic p-TSA (10 mol %) in PhMe at ca. 110 ꢀC
for 10 min to afford the corresponding ylidenes 15 and 16 in high
yields (Scheme 6).
p
-conjugated oligomers and polymers (Scheme 5). p-Conjugated
polymers of thiadiazines have been proposed by both Woodward24
and Rees8,10,11 as potentially stable alternatives to the supercon-
ductor poly(sulfur nitride) (SN)x.
ll
l
l
l
l
Scheme 5.
Scheme 6.

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H.A. Ioannidou, P.A. Koutentis / Tetrahedron 68 (2012) 2590e2597
Interestingly, during the attempted chlorodehydroxylation of 4-
such as morpholine for 2 d at 100 ꢀC, o-phenylenediamine in EtOH
heated at reflux for 2 d and thiophenol in refluxing PhMe for 2 d.
The limited reactivity of the dihalomethanes 18 and 19 could be
attributed to steric effects, due to shielding from the phenyl groups.
methyl-3,5-diphenyl-4H-1,2,6-thiadiazin-4-ol (13) with neat SOCl2
we observed traces of a compound that gave a molecular ion of m/z
298 Da with a chlorine isotope pattern tentatively corresponding to
a chloro-dehydration. As such we investigated the possibility of
further halogenating the (thiadiazinylidene)methanes. The
attempted chlorination of the (diphenylthiadiazinylidene)methane
15 using SOCl2 gave mixtures and was abandoned. Nevertheless,
treating (3,5-diphenyl-4H-1,2,6-thiadiazin-4-ylidene)methane (15)
with NBS (1 equiv) in CCl4 at ca. 20 ꢀC, gave bromo(3,5-diphenyl-
4H-1,2,6-thiadiazin-4-ylidene)methane (17) in 80% yield (Scheme
7). The analogous reactions with NCS and NIS at ca. 20 ꢀC gave
only recovered starting material while at ca. 70 ꢀC the former gave
again recovered starting material and the latter gave a complex
reaction mixture (TLC) and no trace of the target compound. The
analogous reaction of (dithienylthiadiazinylidene)methane 16 led
to mainly unreacted starting material and baseline material.
2.3. Preparation of (thiadiazin-4-ylidene)malononitriles
Prior attempts to condense malononitrile and the dichloro-
thiadiazinone 1 to prepare the dicyanomethylene 2 had failed and
this was tentatively owed to the high reactivity of the chlorine
substituents at C-3 and C-5. With the 3,5-diphenyl- and 3,5-
dithien-2-ylthiadiazinones 9 and 10 in hand the C-3 and C-5 po-
sitions were now blocked and the analogous condensation was
reexamined. Treatment of either diphenyl- or dithienylthia-
diazinones 9 and 10 with malononitrile in the presence of bases
such as Et3N, pyridine, t-BuLi or n-BuLi/diisopropylamine in THF or
the use of Lewis acids TiCl4 in PhH or ammonium acetate in Ac2O, or
simply refluxing the mixture in Ac2O afforded only recovered
starting thiadiazinones. Furthermore, the thiadiazinones 9 and 10
were unreactive towards a series of reagents like TCNE, tetracya-
noethylene oxide (TCNEO), MeI, ethyl diazoacetate and the Wittig
reagent (cyanomethyl)triphenylphosphonium chloride with NaH in
THF. Nevertheless, the ylidenemalononitriles could be prepared
from the more reactive thiones 20 and 21.
2.4. Preparation of thiadiazine-4-thiones
Scheme 7.
Alternative routes to ylidenemalononitriles involve cycloaddi-
tion of TCNE or TCNEO to thiones27e29 and fortunately, the thia-
diazine-4-thiones could be readily prepared. The reaction of
thiadiazinones 9 and 10 with of P2S5 (0.5 equiv) in xylenes heated
at ca. 139 ꢀC for 5 h gave the desired 3,5-diphenyl- and 3,5-dithien-
2-yl-4H-1,2,6-thiadiazine-4-thiones 20 and 21 in 68% and 45%
yields, respectively (1 g scales) (Scheme 9). Interestingly, the
analogous reactions with Lawesson’s reagent (0.5 equiv) in dry
toluene or xylenes heated at ca. 110 ꢀC and 139 ꢀC, respectively, for
12 h led to complex mixtures containing mainly unreacted starting
thiadiazinones (by TLC).
Further attempts to bis halogenate by either treating the
methylene 15 or the monobromoylidene 17 with additional NBS (2
and 3 equiv) in either CCl4 or with Br2 in AcOH led to complex
mixtures but no trace of the dibrominated product (by TLC), as such
this was not pursued further.
2.2. Preparation of dihalo(thiadiazin-4-ylidene)methanes
Fortunately, the dihalomethane thiadiazines 18 and 19 could be
preparedviatheAppelreaction.25 Treatingthediphenylthiadiazinone
9 with Ph3P in CCl4 or CBr4 at elevated temperatures in a sealed tube
and prolonged heating gave the desired dichloro(3,5-diphenyl-4H-
1,2,6-thiadiazin-4-ylidene)methane (18) and dibromo(3,5-diphenyl-
4H-1,2,6-thiadiazin-4-ylidene)methane (19), respectively. In the case
of the CCl4 reaction, heating at ca.140 ꢀC under microwave irradiation
MW (250 W) (70 psi) was the best choice for small scale reactions (up
to 0.75 mmol), giving a short reaction time (1 h) (95%) while with
CBr4, heating with microwave irradiation at ca. 140 ꢀC MW (250 W)
(68 psi) led to lower yields (70%) and the best yield was obtained
when a sealed tube was used for 7 h at ca. 150 ꢀC (91%) (Scheme 8).
Scheme 9.
2.5. Preparation of (thiadiazin-4-ylidene)malononitriles
3,5-Diphenyl-4H-1,2,6-thiadiazine-4-thione (20) treated with
TCNE (1.2 equiv) in PhCl heated to ca. 132 ꢀC for 12 h gave 2-(3,5-
diphenyl-4H-1,2,6-thiadiazin-4-ylidene)malononitrile
(22)
in
a moderate 36% yield together with two purple coloured minor side
products that could not be separated or characterized. The reaction
of the dithienylthiadiazinethione 21 with TCNE, however, led to
a complex reaction mixture and this was not altogether surprising
since TCNE was known to react with thiophenes to give tricyano-
vinyl substituted thiophenes at C-230 and in rare cases DielseAlder
adducts can form.31,32 In light of this we then reacted both diphenyl
and dithienylthiadiazine-4-thiones 20 and 21 with TCNEO
(1.2 equiv) in PhMe heated to ca. 110 ꢀC for 40 min and obtained the
desired ylidenemalononitriles 22 and 24 in 72% and 79% yields,
respectively (Scheme 10). Interestingly, the reaction between
Scheme 8. Reagents and conditions: Hal¼Cl, Ph3P (4 equiv), CCl4, MW (250 W), 140 ꢀ
(70 PSl), 1 h, 95%; Hal¼Br, Ph3P (4 equiv), CBr4 (2 equiv), PhH, MW (250 W), 140 ꢀ
(68 PSl), 1 h, 70% or sealed tube, 150 ꢀC, 7 h, 91%.
C
C
The dibromomethane 19 proved to be stable under several re-
ducing conditions: H2 over Pd/C in EtOH or NaBH4 in MeOH, and
In(0) in AcOH but the use of Zn in HCO2H26 led to decomposition of
the starting material. Furthermore, the dichloromethane 18 and
dibromomethane 19 were stable in the presence of nucleophiles,

H.A. Ioannidou, P.A. Koutentis / Tetrahedron 68 (2012) 2590e2597
2593
Scheme 10.
3,5-diphenyl-4H-1,2,6-thiadiazine-4-thione (20) and TCNEO also
gave 3,5-diphenyl-4H-1,2,6-thiadiazine-4-thione oxide (23) as
a minor side product in 12% yield (Scheme 10). The sulfine 23 could
be prepared directly and in high yield (85%) by treating
the diphenylthiadiazinethione 20 with m-CPBA (1.3 equiv) at
ca. 0 ꢀC for 2 min, however, the analogous reaction with the
dithienylthiadiazine-4-thione 21 gave only decomposition (by TLC),
and this was probably owed to the ability of m-CPBA to oxidise the
electron rich thiophenes.33
replacement of oxygen by either sulfur or carbon substituents
shifted the longest wavelength absorption to the red (Table 2). On
switching the C-4 oxygen for the more powerfully electron with-
drawing C(CN)2 red shifts of 97 and 157 nm were observed for the
diphenyl and dithienylthiadiazinylidenes, respectively.
Table 2
Selected spectroscopic data for 3,5-disubstituted 4H-1,2,6-thiadiazines
The mechanistic rationale for the reactions between TCNE and
TCNEO with thiones to give ylidenemalononitriles and also in the
latter case the sulfine has been previously reported.28,29 Briefly,
both reagents cycloadd to the thione, TCNE via [2þ2] and TCNEO
via [2þ3] cycloadditions. The adducts then fragment via retro-
cycloaddition reactions, tentatively losing in the first case thio-
carbonyl cyanide and in the second case carbonyl cyanide and
elemental sulfur, leaving behind the desired ylidenemalononitriles.
It has been postulated that sulfine 23 forms by direct attack of the
thione onto the TCNEO oxygen leading to an effective oxygen
transfer and generation of TCNE as a reaction side product.29
In light of this success we extended the [2þ3] cycloaddition
chemistry of the thiadiazinethiones by reacting both the diphenyl-
and dithienylthiadiazinethiones 20 and 21 with ethyl diazoacetate
(1.5 equiv) in PhMe at ca. 20 ꢀC for 1 h and isolated ethyl 2-(3,5-
diphenyl-4H-1,2,6-thiadiazin-4-ylidene)acetate (26) in 97% yield
from the former (Scheme 11) but failed to obtain a product from the
dithienyl analogue, which gave a complex reaction mixture. Ten-
tatively this could be attributed to the known reactivity of thio-
phenes with ethyl diazoacetate that can lead to competing
cyclopropanation reactions.34
Compound no. R1
X
lmax (DCM)/nm (log
3 )
13C (ppm) C(CN)2
9
Ph
O
348 (3.28)
358 (3.19)
361 (3.19)
392 (2.84)
416 (3.37)
d
18
19
15
20
22
10
16
21
24
Ph
Ph
Ph
Ph
CCl2
CBr2
CH2
S
d
d
d
d
Ph
C(CN)2 445 (3.07)
O
79.0 (in CDCl3)
d
Thien-2-yl
Thien-2-yl CH2
Thien-2-yl
327 (3.74)
395 (3.59)
454 (3.15)
d
S
d
Thien-2-yl C(CN)2 484 (3.29)
78.6 (in CDCl3)
The 13C NMR data of ylidenemalononitriles 22 and 24 also in-
dicated that a considerable negative charge was located on the
central carbon of the malononitrile group [dC C(CN)2 22 (R1¼Ph)
79.0 ppm and 24 (R1¼thien-2-yl) 78.6 ppm] indicating the pres-
ence of a considerable pushepull effect,35 the ‘push’ originating
presumably from the electron rich arenes at C-3 and C-5 and also
from the thiadiazine ring sulfur. The above data tentatively sup-
port that electron transfer occurred from the 3,5-diaryl sub-
stituents to the thiadiazine ring and that modifications at the
C-4 positions strongly affect the properties of these 3,5-
diarylthiadiazinylidenes.
3. Conclusions
Scheme 11.
The modification of 3,5-diphenyl and 3,5-dithien-2-yl-4H-1,2,6-
thiadiazin-4-ones 9 and 10 at the C-4 position using NaBH4 or MeLi
has successfully afforded 4H-thiadiazin-4-ols. Furthermore, various
4H-ylidenemethanes could be prepared either via the dehydration
of 4-methylthiadiazin-4-ols or via the Appel reaction of thiadiazi-
nones with Ph3P and CX4 (X¼Br or Cl), or via cyclo-
additiondretrocycloaddition reactions of the readily prepared
thiadiazinethiones and TCNEO. Spectroscopic studies indicate that
modifying the C-4 position can dramatically alter the longest
wavelength absorption in the visible spectra and this information
2.6. Comparison of selected spectroscopic data of
thiadiazinylidenes
With a range of 4H-1,2,6-thiadiazin-4-ylidenes in hand that
varied at C-4, the absorption properties in the UV/vis absorption
spectra could be compared. This comparison can yield qualitative
information about optical band gaps that can be used in the design
of oligomers or polymers needed for further materials studies. On
comparing the 3,5-diphenylthiadiazines it was clear that the
can be of use for the design of p-extended oligomers and polymers.

2594
H.A. Ioannidou, P.A. Koutentis / Tetrahedron 68 (2012) 2590e2597
4. Experimental
1373w, 1352w, 1287w, 1250w, 1246m, 1088w, 1063m, 1022w, 999s,
926m, 916m, 907w, 856m, 847s, 795w; dH (500 MHz; CDCl3) 7.63
(2H, d, J 3.5, thienyl H), 7.50 (2H, d, J 5.0, thienyl H), 7.12 (2H, dd, J
4.5, 4.5, thienyl H-4), 5.91 (1H, s, CHOH); dC (125 MHz; CDCl3) 146.1
(s), 142.9 (s), 130.6 (d), 127.9 (d), 126.4 (d), 54.0 (d); m/z (EI) 280
(Mþ, 25%), 263 (6), 233 (2), 171 (8), 142 (35), 127 (4), 115 (6), 112 (6),
110 (100), 97 (5), 84 (17), 71 (8), 64 (11), 58 (11), 49 (12).
4.1. General procedures
THF was distilled over sodium in the presence of benzophenone
and Et2O was distilled over CaH2. Reactions were protected by CaCl2
drying tubes. Anhydrous Na2SO4 was used for drying organic ex-
tracts and all volatiles were removed under reduced pressure. All
reaction mixtures and column eluents were monitored by TLC us-
ing commercial glass backed thin layer chromatography (TLC)
plates (Merck Kieselgel 60 F254). The plates were observed under
UV light at 254 and 365 nm. The technique of dry flash chroma-
tography was used throughout for all non-TLC scale chromato-
graphic separations using Merck Silica Gel 60 (less than
0.063 mm).36 Melting points were determined using a PolyTherm-
A, Wagner & Munz, Koefler-Hotstage Microscope apparatus. De-
composition points (decomp.) and mp >250 ꢀC were determined
using a TA Instruments DSC Q1000 with samples hermetically
sealed in aluminium pans under an argon atmosphere, using
heating rates of 5 ꢀC/min. Solvents used for recrystallization are
indicated after the melting point. A CEM Discover Microwave Re-
actor was used for microwave experiments. UV spectra were ob-
tained using a PerkineElmer Lambda-25 UV/vis spectrophotometer
and inflections are identified by the abbreviation ‘inf’. IR spectra
were recorded on a Shimadzu FTIR-NIR Prestige-21 spectrometer
with Pike Miracle Ge ATR accessory and strong, medium and weak
peaks are represented by s, m and w, respectively. 1H and 13C NMR
spectra were recorded on a Bruker Avance 500 machine (at 500 and
125 MHz, respectively). Deuterated solvents were used for homo-
nuclear lock and the signals are referenced to the deuterated sol-
vent peaks. Low resolution (EI) mass spectra were recorded on
a Shimadzu Q2010 GCMS with direct inlet probe. 3,5-Diphenyl-4H-
4.4. 4-Methyl-3,5-diphenyl-4H-1,2,6-thiadiazin-4-ol (13)
To a stirred solution of 3,5-diphenyl-4H-1,2,6-thiadiazin-4-one
(9) (100 mg, 0.376 mmol) in THF (4 mL) at ca. 0 ꢀC protected from
moisture with a CaCl2 drying tube, was added MeLi (0.33 mL,
1.50 mmol) and the mixture was left to warm to ca. 10 ꢀC until no
starting material remained (TLC). The mixture was then diluted
(DCM), washed (H2O), dried (Na2SO4) and adsorbed onto silica.
Chromatography (hexane/DCM, 1:1) gave the title compound 13
(95.6 mg, 90%) as pale yellow needles; mp (DSC) onset 122.9 ꢀC,
peak 123.3 ꢀC (from cyclohexane); Rf 0.33 (hexane/DCM, 1:1).
Found: C, 68.16; H, 5.11; N, 9.83. C16H14N2OS requires C, 68.06; H,
5.00; N, 9.92%; lmax (DCM)/nm 235 (log 3.23), 248 inf (3.14), 284
3
(3.01), 340 (3.03); nmax/cmꢁ1 3333brw (OH), 3055w (Ar CH),
2992w, 1491w, 1439m, 1369m, 1273m, 1179m, 1155w, 1078w,
1057m, 1032w, 1001w, 982w, 947w, 926w, 841w, 818m, 768s, 762s;
dH (500 MHz; CDCl3) 7.82 (4H, d, J 7.5, Ph H), 7.42e7.37 (6H, m, Ph
H), 2.43 (1H, s, OH), 1.66 (3H, s, CH3); dC (125 MHz; CDCl3) 155.8 (s),
135.1 (s), 130.1 (d), 129.6 (d), 128.1 (d), 68.4 (s), 19.0 (CH3); m/z (EI)
282 (Mþ, 7%), 267 (2), 263 (2), 239 (5), 179 (31), 160 (4), 146 (7), 136
(100), 109 (9), 104 (27), 85 (4), 77 (20), 71 (6), 57 (8), 51 (9).
4.5. 4-Methyl-3,5-dithien-2-yl-4H-1,2,6-thiadiazin-4-ol (14)
1,2,6-thiadiazin-4-one
9
and
3,5-di-(thien-2-yl)-4H-1,2,6-
Following the procedure described for compound 13 treatment
of 3,5-dithien-2-yl-4H-1,2,6-thiadiazin-4-one (10) (105 mg,
0.376 mmol) gave the title compound 14 (103 mg, 98%) as yellow
plates; mp 32e34 ꢀC; Rf 0.33 (hexane/DCM,1:1). Found: C, 49.07; H,
3.39; N, 9.66. C12H10N2OS3 requires C, 48.95; H, 3.42; N, 9.51%; lmax
thiadiazin-4-one 10,13 TCNE37 and TCNEO38 were prepared
according to literature procedures.
4.2. 3,5-Diphenyl-4H-1,2,6-thiadiazin-4-ol (11)
(DCM)/nm 277 (log
3
4.23), 354 (3.90), 429 (3.95); nmax/cmꢁ1
To a stirred suspension of 3,5-diphenyl-4H-1,2,6-thiadiazin-4-
one (9) (100 mg, 0.376 mmol) in MeOH (4 mL) at ca. 20 ꢀC, was
added NaBH4 (28.4 mg, 0.75 mmol) and the mixture was placed to
a preheated oil bath at ca. 50 ꢀC until no starting material remained
(TLC). The mixture was then diluted (DCM), washed (H2O) and
dried (Na2SO4) to give the title compound 11 (98 mg, 97%) as yellow
flakes; mp 75e77 ꢀC (from pentane); Rf 0.60 (DCM). Found: C,
67.03; H, 4.62; N, 10.32. C15H12N2OS requires C, 67.14; H, 4.51; N,
10.44%; lmax (DCM)/nm 240 inf (306), 246 (3.07), 277 inf (2.91), 348
(3.03); nmax/cmꢁ1 3356w, 3310w, 3260w (OH), 3059w (Ar CH),
1703w, 1493w, 1445s, 1385m, 1360s, 1265s, 1234w, 1200m, 1182w,
1157w, 1070s, 1040w, 1020s, 969s, 932m, 910w, 847m; dH
(500 MHz; CDCl3) 7.99e7.97 (5H, m, Ph H), 7.47e7.46 (5H, m, Ph H),
6.07 (1H, s, CHOH); dC (125 MHz; CDCl3) 150.3 (s), 136.6 (s), 130.6
(d), 128.8 (d), 126.8 (d), 52.4 (d, CHOH); m/z (EI) 268 (Mþ, 7%), 267
(Mþꢁ1, 7), 252 (21), 251 (6), 221 (100), 220 (43), 149 (25), 137 (11),
135 (9), 121 (7), 116 (14), 103 (36), 77 (36), 51 (18).
3433brw (OH), 3100w and 3076w (Ar CH), 2976w, 1697w, 1647w,
1541m, 1520w, 1418s,1356m, 1267m, 1229m, 1211w, 1169m, 1078w,
1047s, 976w, 949w, 905w, 851s, 812w, 779w; dH (500 MHz; CDCl3)
7.87 (2H, d, J 4.0, thienyl H), 7.42 (2H, d, J 5.0, thienyl H), 7.05 (2H, dd,
J 4.5, 4.5, thienyl H-4), 3.04 (1H, s, COHCH3), 1.62 (3H, s, CH3); dC
(125 MHz; CDCl3) 150.4 (s), 139.5 (s), 130.4 (d), 130.1 (d), 127.7 (d),
66.8 (s), 19.9 (CH3); m/z (EI) 294 (Mþ, 49%), 279 (15), 251 (7), 185
(23), 170 (4), 142 (100), 116 (9), 109 (24), 84 (12), 71 (7), 58 (7).
4.6. (3,5-Diphenyl-4H-1,2,6-thiadiazin-4-ylidene)methane
(15)
To
a stirred solution of 4-methyl-3,5-diphenyl-4H-1,2,6-
thiadiazin-4-ol (13) (50.0 mg, 0.177 mmol) in PhMe (2 mL) at ca.
20 ꢀC was added p-TSA (3.4 mg, 0.018 mmol) and the mixture was
heated at ca. 110 ꢀC (preheated oil bath) until no starting material
remained (TLC). The reaction mixture was then allowed to cool to ca.
20 ꢀC, diluted (DCM) and adsorbed onto silica. Chromatography
(hexane/DCM, 7:3) gave the title compound 15 (42.8 mg, 90%) as
yellow plates; mp 67e68 ꢀC (from cyclohexane); Rf 0.70 (hexane/
DCM, 1:1). Found: C, 72.74; H, 4.67; N, 10.69. C16H12N2S requires C,
4.3. 3,5-Dithien-2-yl-4H-1,2,6-thiadiazin-4-ol (12)
Following the procedure described for the preparation of com-
pound 11, treatment of 3,5-dithien-2-yl-4H-1,2,6-thiadiazin-4-one
(10) (105 mg, 0.376 mmol) in MeOH/DCM (1:1, 4 mL) gave the ti-
tle compound 12 (103 mg, 98%) as yellow needles; mp 110e112 ꢀC
(from cyclohexane); Rf 0.50 (DCM). Found: C, 47.20; H, 2.79; N, 9.87.
C11H8N2OS3 requires C, 47.12; H, 2.88; N, 9.99%; lmax (DCM)/nm 269
72.70; H, 4.58; N,10.60%; lmax (DCM)/nm 247 (log 3.42), 333 (3.09),
3
392 (2.84); nmax/cmꢁ1 3053w (Ar CH), 2955w, 2924w, 2853w,
1593w,1576w,1531m,1489m,1472w,1441m,1396w,1352s,1277m,
1175m,1076m,1028w, 999w, 989m, 968w, 918s, 851w, 841w, 831w,
781s; dH (500 MHz; CDCl3) 7.82e7.81 (4H, m, Ph H), 7.45e7.43 (6H,
m, Ph H), 5.59 (2H, s, CH2); dC (125 MHz; CDCl3) 158.2 (s), 137.2 (s),
130.2 (d), 128.6 (d), 128.5 (s), 127.5 (d), 117.3 (]CH2); m/z (EI) 264
(log
3
3.23), 285 inf (3.10), 381 (3.33), 389 (3.32), 406 inf (3.19);
nmax/cmꢁ1 3480w, 3292brw (OH), 3088w (Ar CH), 1533m, 1425s,

H.A. Ioannidou, P.A. Koutentis / Tetrahedron 68 (2012) 2590e2597
2595
(Mþ, 84%), 263 (100), 185 (4), 160 (67), 134 (6), 115 (42), 109 (5), 103
4.10. Dibromo(3,5-diphenyl-4H-1,2,6-thiadiazin-4-ylidene)
(11), 89 (14), 77 (18), 63 (10), 58 (9), 51 (14).
methane (19)
3,5-Diphenyl-4H-1,2,6-thiadiazin-4-one
(9)
(100 mg,
4.7. (3,5-Dithien-2-yl-4H-1,2,6-thiadiazin-4-ylidene)methane
0.365 mmol), Ph3P (394 mg, 1.50 mmol), CBr4 (249 mg,
0.751 mmol) and dry PhH (1 mL) were placed in a sealed tube and
heated to 150 ꢀC for 7 h until no starting material remained (TLC).
After the reaction was finished, the reaction mixture was diluted
with DCM and adsorbed onto silica. Chromatography (hexane/
DCM, 7:3) gave the title compound 19 (144 mg, 91%) as yellow
plates; mp (DSC) onset 151.7 ꢀC, peak 153.5 ꢀC (from pentane); Rf
0.75 (hexane/DCM, 7:3). Found: C, 45.58; H, 2.42; N, 6.61.
C16H10Br2N2S requires C, 45.52; H, 2.39; N, 6.64%; lmax (DCM)/nm
(16)
Following the procedure described for compound 15 treatment
of 4-methyl-3,5-dithien-2-yl-4H-1,2,6-thiadiazin-4-ol (14) (53 mg,
0.18 mmol) gave the title compound 16 (47.7 mg, 96%) as orange
plates; mp 66e67 ꢀC (from pentane, fridge); Rf 0.70 (hexane/DCM,
1:1). Found: C, 52.22; H, 2.83; N, 10.07. C12H8N2S3 requires C, 52.14;
H, 2.92; N, 10.14%; lmax (DCM)/nm 254 inf (log 3.44), 273 (3.61),
3
299 inf (3.39), 382 (3.57), 395 (3.59); nmax/cmꢁ1 3100w and 3075w
(Ar CH), 1591w, 1520m, 1504w, 1425s, 1352w, 1337w, 1271w,
1231m, 1055m, 955m, 943w, 926m, 920m, 905w, 851s; dH
(500 MHz; CDCl3) 7.65 (2H, dd, J 3.4, 1.3, thienyl H), 7.46 (2H, dd, J
5.3, 1.2, thienyl H), 7.07 (2H, dd, J 5.0, 4.0, thienyl H-4), 5.96 (2H, s,
CH2); dC (125 MHz; CDCl3) 149.6 (s), 141.4 (s), 130.3 (d), 128.4 (s),
127.4 (d), 127.3 (d), 114.8 (CH2); m/z (EI) 276 (Mþ,100%), 243 (6), 231
(4), 192 (5), 167 (13), 140 (8), 121 (19), 109 (9), 97 (7), 77 (14), 69 (7),
58 (9).
245 (log
3
3.33), 261 (3.38), 361 (3.19); nmax/cmꢁ1 3057w (Ar CH),
1557w, 1508w, 1487w, 1441m, 1315s, 1294m, 1277w, 1175m, 1134m,
1076w, 1032w, 1024w, 1009w, 997w, 920w, 862s, 856m, 779s, 766s;
dH (500 MHz; CDCl3) 7.96 (4H, d, J 7.5, Ph H), 7.50e7.42 (6H, m, Ph
H); dC (125 MHz; CDCl3) 149.1 (s), 134.3 (s), 133.6 (s), 130.4 (d), 128.9
(d), 127.6 (d), 91.9 (s); m/z (EI) 424 (Mþþ4, 7%), 422 (Mþþ2, 17), 420
(Mþ, 7), 343 (7), 341 (7), 262 (100), 216 (6), 159 (17), 131 (13), 113
(18), 109 (10), 77 (15), 63 (8), 51 (16).
4.11. 3,5-Diphenyl-4H-1,2,6-thiadiazine-4-thione (20)
4.8. Bromo(3,5-diphenyl-4H-1,2,6-thiadiazin-4-ylidene)
methane (17)
To a stirred solution of 3,5-diphenyl-4H-1,2,6-thiadiazin-4-one
(9) (100 mg, 0.375 mmol) in xylene (4 mL) was added P2S5
(83.5 mg, 0.188 mmol) and the reaction mixture was heated at ca.
139 ꢀC until no starting material remained (TLC). The reaction
mixture was then allowed to cool to ca. 20 ꢀC, filtered through a pad
of silica gel and washed with hexane (30 mL) to remove xylene and
then elution with hexane/DCM (7:3) gave the title compound 20
(72 mg, 68%) as yellow needles; mp 109e110 ꢀC (from pentane/
DCM, at ca. 0 ꢀC); Rf 0.65 (hexane/DCM, 7:3). Found: C, 63.82; H,
3.50; N, 9.95. C15H10N2S2 requires C, 63.80; H, 3.57; N, 9.92%; lmax
To a stirred solution of (3,5-diphenyl-4H-1,2,6-thiadiazin-4-
ylidene)methane (13) (50.0 mg, 0.189 mmol) in CCl4 (2 mL) at ca.
20 ꢀC, was added NBS (33.8 mg, 0.19 mmol) and stirred until no
starting material remained. The reaction mixture was then adsor-
bed onto silica and chromatography (hexane/DCM, 7:3) gave the
title compound 17 (52 mg, 80%) as yellow plates; mp 98e99 ꢀC
(from pentane, fridge); Rf 0.74 (hexane/DCM, 7:3). Found: C, 55.96;
H, 3.19; N, 8.23. C16H11BrN2S requires C, 55.99; H, 3.23; N, 8.16%;
(DCM)/nm 235 inf (log
3
3.43), 253 (3.57), 416 (3.37); nmax/cmꢁ1
lmax(DCM)/nm 246 (log
3
3.51), 350 (3.24), 381 inf (3.08), 397
(3.04); nmax/cmꢁ1 3055w (Ar CH), 1574w, 1506w, 1491w, 1443w,
1341m, 1308w, 1281w, 1238w, 1173w, 1161w, 1074w, 1028w, 1007w,
995w, 974w, 922w, 841m, 802w, 793w, 716s; dH (500 MHz; CDCl3)
7.98e7.96 (2H, m, Ph H), 7.85 (2H, dd, J 7.5, 1.3, Ph H), 7.48e7.46 (6H,
m, Ph H), 6.85 (1H, s); dC (125 MHz; CDCl3) (1 quaternary missing)
153.2 (s), 152.0 (s), 135.7 (s), 130.8 (d), 130.1 (d), 130.1 (s), 129.0 (d),
128.7 (d), 127.8 (d), 127.4 (d), 110.4 (d, CHBr); m/z (EI) 344 (Mþþ2,
11%), 342 (Mþ, 11), 263 (778), 185 (6), 160 (100), 133 (11), 131 (17),
116 (17), 114 (21), 109 (13), 89 (9), 77 (18), 65 (6), 51 (12).
3030w (Ar CH), 1578w, 1466w, 1435w, 1425w, 1329m, 1319m,
1290w, 1271w, 1177w, 1152s, 1072w, 1030w, 1001w, 910w, 824m,
773m; dH (500 MHz; CDCl3) 7.84 (4H, d, J 7.5, Ph H), 7.46e7.42 (6H,
m, Ph H); dC (125 MHz; CDCl3) 191.6 (s, C]S), 169.0 (s), 137.7 (s),
130.6 (d), 128.3 (d), 127.9 (d); m/z (EI) 282 (Mþ, 52%), 281 (Mþꢁ1,
100), 204 (4), 179 (8), 141 (5), 135 (13), 121 (22), 103 (41), 89 (15), 77
(19), 76 (19), 63 (6), 51 (12).
4.12. 3,5-Dithien-2-yl-4H-1,2,6-thiadiazine-4-thione (21)
4.9. Dichloro(3,5-diphenyl-4H-1,2,6-thiadiazin-4-ylidene)
methane (18)
Following the procedure described for compound 20 treatment
of 3,5-dithien-2-yl-4H-1,2,6-thiadiazin-4-one (10) (104 mg,
0.375 mmol) gave the title compound 21 (50 mg, 45%) as bright
green needles; mp 134e136 ꢀC (from cyclohexane); Rf 0.75 (hex-
ane/DCM, 7:3). Found: C, 44.92; H, 2.00; N, 9.45. C11H6N2S4 requires
3,5-Diphenyl-4H-1,2,6-thiadiazin-4-one
(9)
(100 mg,
0.365 mmol), Ph3P (394 mg, 1.50 mmol) and CCl4 (1 mL) were
placed in a MW reactor (250 W) and heated to ca.140 ꢀC (70 psi) for
1 h. The reaction mixture was then allowed to cool to ca. 20 ꢀC,
diluted (DCM) and adsorbed onto silica. Chromatography (hexane/
DCM, 7:3) gave the title compound 18 (119 mg, 95%) as yellow
plates; mp 154e156 ꢀC (from pentane); Rf 0.75 (hexane/DCM, 7:3).
Found: C, 57.75; H, 2.96; N, 8.32. C16H10Cl2N2S requires C, 57.67; H,
C, 44.87; H, 2.05; N, 9.51%; lmax (DCM)/nm 296 (log
3
3.35), 454
(3.15); nmax/cmꢁ1 3088w (Ar CH), 1491w, 1412s, 1391w, 1350s,
1306s, 1260m, 1223w, 1211w, 1161s, 1136w, 1113w, 1078w, 1071w,
1057w, 947w, 914w, 874w, 851m, 839w, 802s; dH (500 MHz; CDCl3)
8.29 (2H, dd, J 4.0, 1.0, thienyl H), 7.56 (2H, dd, J 5.0, 1.5, thienyl H),
7.15 (2H, dd, J 4.5, 4.0, thienyl H); dC (125 MHz; CDCl3) 181.7 (s, C]
S), 160.3 (s), 139.1 (s), 133.6 (d), 132.7 (d), 126.9 (d); m/z (EI) 294
(Mþ, 100%), 293 (93), 261 (5), 210 (4), 185 (12), 147 (7), 141 (26), 139
(25), 127 (12), 115 (14), 109 (80), 95 (24), 71 (16), 69 (18), 58 (14).
3.02; N, 8.41%; lmax(DCM)/nm 247 (log 3.41), 257 inf (3.37), 358
3
(3.19); nmax/cmꢁ1 3059w (Ar CH), 1574w, 1506w, 1489w, 1443m,
1317m, 1296m, 1246w, 1177w, 1138w, 1076w, 1026w, 928s, 914w,
878s, 843w, 781s, 768s; dH (500 MHz; CDCl3) 7.93 (4H, d, J 7.5, Ph
H), 7.50e7.43 (6H, m, Ph H); dC (125 MHz; CDCl3) 148.1 (s), 134.8 (s),
130.4 (d), 128.9 (d), 127.4 (d), 126.2 (s), 121.2 (s); m/z (EI) 336
(Mþþ4, 4%), 334 (Mþþ2, 17), 332 (Mþ, 26), 299 (13), 297 (36), 294
(33), 262 (27), 215 (6), 196 (35), 194 (100), 185 (36), 183 (56), 159
(11), 152 (6), 148 (20), 139 (9), 130 (18), 121 (6), 113 (23), 109 (9), 103
(6), 77 (22), 63 (12), 51 (18).
4.13. 2-(3,5-Diphenyl-4H-1,2,6-thiadiazin-4-ylidene)
malononitrile (22)
To a stirred solution of 3,5-diphenyl-4H-1,2,6-thiadiazine-4-
thione (20) (100 mg, 0.355 mmol) in PhCl (2 mL) was added TCNE
(54.6 mg, 0.426 mmol) and the reaction mixture was heated at ca.

2596
H.A. Ioannidou, P.A. Koutentis / Tetrahedron 68 (2012) 2590e2597
132 ꢀC until no starting material remained (TLC). The reaction
mixture was then allowed to cool to ca. 20 ꢀC, diluted (DCM) and
adsorbed onto silica. Chromatography (hexane/DCM, 1:1) gave the
title compound 22 (35.6 mg, 79%) as yellow needles; mp (DSC) onset
213.2 ꢀC, peak 214.5 ꢀC (from pentane/DCM, 0 ꢀC); Rf 0.40 (hexane/
DCM, 1:1). Found: C, 68.86; H, 3.15; N, 17.73. C18H10N4S requires C,
4.16. Ethyl 2-(3,5-diphenyl-4H-1,2,6-thiadiazin-4-ylidene)
acetate (26)
To a stirred solution of 3,5-diphenyl-4H-1,2,6-thiadiazine-4-
thione (21) (100 mg, 0.355 mmol) in PhMe (4 mL) at ca. 20 ꢀC was
added ethyl diazoacetate (56 mL, 0.533 mmol) and the reaction
68.77; H, 3.21; N, 17.82%; lmax (DCM)/nm 261 (log
3
3.31), 381
mixture was stirred at this temperature until no starting material
remained (TLC). The reaction mixture was then diluted with DCM
(20 mL) and adsorbed onto silica. Chromatography (hexane/DCM,
1:1) gave the title compound 26 as yellow plates; mp (DSC) onset
82.0 ꢀC, peak 84.0 ꢀC (from pentane, at ca. 0 ꢀC); Rf 0.41 (hexane/
DCM, 1:1). Found: C, 67.73; H, 4.85; N, 8.28. C19H16N2O2S requires
(2.91), 445 (3.07); nmax/cmꢁ1 3046w (Ar CH), 2218m (C^N), 1512s,
1491w, 1477s, 1439s, 1343s, 1277m, 1177w, 1159w, 1103w, 1078w,
1028w, 999w, 966w, 939w, 920w, 837w, 818s, 797m, 775m; dH
(500 MHz; CDCl3) 7.87 (4H, br s, Ph H), 7.59 (6H, br s, Ph H); dC
(125 MHz; CDCl3) 150.4 (s), 142.7 (s), 134.7 (s), 132.1 (d), 129.5 (d),
127.8 (d), 111.8 (s, C^N), 79.0 [s, C(C^N)2]; m/z (EI) 314 (Mþ, 23%),
288 (5), 210 (9), 177 (16), 167 (15), 149 (100), 138 (9), 125 (7), 121
(10), 113 (14), 111 (14), 105 (10), 99 (12), 97 (17), 93 (10), 84 (41), 77
(12), 71 (41), 57 (56), 51 (21). Further elution (DCM) gave a mixture
of two purple compounds, which could not be separated or
characterized.
C, 67.84; H, 4.79; N, 8.33%; lmax(DCM)/nm 242 (log
3
3.61), 253
inf (3.58), 276 inf (3.40), 380 (3.39), 385 inf (3.36); nmax/cmꢁ1
3059w (Ar CH), 2982w, 2938w, 2901w, 1703s (C]O), 1599w,
1512w, 1489w, 1472w, 1439m, 1395w, 1368w, 1354m, 1315w,
1267s, 1180w, 1153w, 1123w, 1078w, 1036m, 1007w, 966w, 930w,
876m, 833w, 806w, 776m; dH (500 MHz; CDCl3) 7.96 (2H, d, J 5.0,
Ph H), 7.89 (2H, d, J 7.0, Ph H), 7.48 (3H, br s, Ph H), 7.42e7.40 (3H,
m, Ph H), 3.72 (2H, q, J 7.0, CH2), 0.93 (3H, t, J 7.0, CH3); dC
(125 MHz; CDCl3) 165.3 (s), 152.3 (s), 152.2 (s), 137.8 (s), 135.5 (s),
132.1 (s), 130.7 (d), 130.0 (d), 129.0 (d), 128.7 (d), 128.0 (d), 126.0
(d), 116.6 (d, CHCO2Et), 60.8 (CH2), 13.7 (CH3); m/z (EI) 336 (Mþ,
21%), 307 (9), 291 (6), 262 (100), 216 (3), 204 (2), 185 (9), 160
(55), 133 (8), 121 (5), 116 (13), 109 (10), 103 (7), 89 (8), 77 (19), 65
(7), 51 (8).
4.14. 2-(3,5-Diphenyl-4H-1,2,6-thiadiazin-4-ylidene)
malononitrile (22) and 3,5-diphenyl-4H-1,2,6-thiadiazine-4-
thione oxide (23)
To a stirred solution of 3,5-diphenyl-4H-1,2,6-thiadiazine-4-
thione (20) (100 mg, 0.355 mmol) in PhMe (2 mL) was added
TCNEO (61.3 mg, 0.426 mmol) and the reaction mixture was heated
at ca. 110 ꢀC until no starting material remained (TLC). The reaction
mixture was then allowed to cool to ca. 20 ꢀC, diluted (DCM) and
adsorbed onto silica. Chromatography (hexane/DCM, 1:1) gave the
title compound 22 (88 mg, 79%) as yellow needles; mp (DSC) onset
213.2 ꢀC, peak 214.5 ꢀC (from pentane/DCM, 0 ꢀC), identical to that
described above. Further elution (hexane/DCM, 1:1) gave the title
compound 23 (13.2 mg, 12%) as red flakes; mp 124e125.5 ꢀC (from
pentane/EtOH, at ca. 0 ꢀC); Rf 0.50 (hexane/DCM, 1:1). Found: C,
60.33; H, 3.29; N, 9.31. C15H10N2OS2 requires C, 60.38; H, 3.38; N,
Acknowledgements
The authors thank the Cyprus Research Promotion Foundation
(grant nos. ENISX/0504/08 and NEKYP/0308/02) for financial
support. Furthermore, the authors thank the following organiza-
tions in Cyprus for generous donations of chemicals and glassware:
the State General Laboratory, the Agricultural Research Institute,
the Ministry of Agriculture, MedoChemie Ltd and Biotronics Ltd.
Finally, we thank the A.G. Leventis Foundation for helping to es-
tablish the NMR facility in the University of Cyprus.
9.39%; lmax(DCM)/nm 251 (log 3.18), 284 (3.02), 426 (2.90); nmax/
3
cmꢁ1 3059w (Ar CH), 1483w, 1437w, 1321m, 1302w, 1269w, 1165w,
1142w, 1082s, 1074m, 1030w, 999w, 986w, 922w, 841w, 793m,
770m; dH (500 MHz; CDCl3) 7.95 (2H, d, J 7.0, Ph H), 7.77e7.75 (2H,
m, Ph H), 7.56e7.47 (6H, m, Ph H); dC (125 MHz; CDCl3) 166.0 (s),
153.5 (s), 153.45 (s), 136.2 (s), 135.1 (s), 132.0 (d), 131.1 (d), 129.3 (d),
128.4 (d), 128.0 (d), 127.3 (d); m/z (EI) 298 (Mþ, 100%), 281 (75), 269
(15), 265 (15), 249 (8), 220 (11), 205 (7), 190 (11), 175 (21), 167 (8),
149 (13), 146 (10), 135 (15), 121 (31), 103 (38), 89 (10), 77 (49), 63
(11), 51 (29).
References and notes
1. Breining, T.; Cimpoia, A. R.; Mansour, T. S.; Cammack, N.; Hopewell, P.; Ashman,
C. Heterocycles 1995, 41, 87e94.
2. McKendry, L. H.; Bland, W. P. U.S. Patent. 4,155,746, 1979.
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€
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3
3.45), 281 (3.63),
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422 (3.41), 484 (3.29); nmax/cmꢁ1 3111w and 3094w (Ar CH), 2218m
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1248w, 1225w, 1109w, 1057w, 907w, 858m, 851m, 828w, 816m; dH
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ꢀ
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