A one-pot synthesis of 2,3-dihydro-2-thioxothieno[2,3-d]thiazoles

Article abstract of DOI:10.1055/s-2001-11440

A variety of 3,5-disubstituted-2,3-dihydro-2-thioxothieno[2,3-d]thiazoles 3a-h including alkyl-, aryl- and heteryl- substituents were synthesized in excellent yields in a one pot re-action between 3-substituted-5-(2-aryl (or heteryl)-2-oxoethyl)-4-oxo-2-thioxo-1,3-thiazolidines 1a-h and either tetraphosphorous decasulfide (Method A) or Lawesson's reagent (Method B). However, fair yields of 3 were also obtained along with unknown oily products when the (E,Z)-5-(2-aryl-2-oxoethylidene) derivatives 2f, g were similarly treated with the same reagents. Structures of products were supported by microanalytical and spectral evidence. A rationalization for the route of conversion is given.

Full text of DOI:10.1055/s-2001-11440

PAPER
413
A One-Pot Synthesis of 2,3-Dihydro-2-Thioxothieno[2,3-d]Thiazoles
Mohamed T. Omar, Nadia K. El-Aasar,* Khaled F. Saied
Chemistry Department, Faculty of Science, Ain Shams University Abbassia, Cairo, Egypt
E-Mail: osmanyo@intouch.com
Received 22 July 2000; revised 16 November 2000
from thiophenes,1 13 and few of which from thiazole de-
rivatives.14,15 The present work is aimed to present a new
and easy one-pot synthesis of this ring system starting
from the readily accessible, well crystalline compounds,
Abstract:
A
variety of 3,5-disubstituted-2,3-dihydro-2-
thioxothieno[2,3-d]thiazoles 3a h including alkyl-, aryl- and heter-
yl- substituents were synthesized in excellent yields in a one pot re-
action between 3-substituted-5-(2-aryl (or heteryl)-2-oxoethyl)-4-
oxo-2-thioxo-1,3-thiazolidines 1a h and either tetraphosphorous namely 3-substituted-5-(2-aryl-2-oxoethyl)-2-thioxo-4-
decasulfide (Method A) or Lawesson’s reagent (Method B). How-
oxo-1,3-thiazolidines 1a g, as well as the respective 5-(2-
ever, fair yields of 3 were also obtained along with unknown oily
aryl-2-oxoethylidene) derivatives 2f, g by reacting them
products when the (E,Z)-5-(2-aryl-2-oxoethylidene) derivatives 2f,
with tetraphosphorous decasulfide or Lawesson’s reagent
g were similarly treated with the same reagents. Structures of prod-
Scheme 1). Compounds 1a g were synthesized following
ucts were supported by microanalytical and spectral evidence. A ra-
tionalization for the route of conversion is given.
the method of Nagase16 by treating the respective aroyl-
propenoic acids with ammonium aryldithiocarbamates,
whereas compounds 2f, g were obtained by the reaction of
Key words: 1,3-thiazolidines, thionation, 1,2-dithiines, thiazoles,
fused thieno-bithienyls, sulfur, heterocycles
1f, g with bromine in glacial acetic acid. Structures of 1
and 2 were based on analytical and spectral evidence. The
1
AMX pattern exhibited in the H NMR spectra of com-
Several multistep methods have been adopted for the syn-
pounds 1, has been collapsed into olefinic singlets in com-
thesis of thieno[2,3-d]thiazoles, most of them starting
Synthesis of 3a h
Scheme 1
Synthesis 2001, No. 3, 413–418 ISSN 0039-7881 © Thieme Stuttgart · New York

414
M. T. Omar et al.
PAPER
Fragmentation pathways of compounds 3a h
Scheme 2
pounds 2. Compounds 2 are undoubtedly mixtures of 3 hours produced excellent yields of the respective
E- and Z-isomers and the integrated proton ratios of the 3,5-disubstituted 2,3-dihydro-2-thioxothieno[2,3-d]thiaz-
olefinic singlets showed that in the cases of 2f and g the oles 3a h, in the former case, and in relatively lower
Z-isomer constitutes 50% of (E,Z)-2f and 19% of (E,Z)- yields, for the latter one. The structures of 3a h were de-
2g, respectively. Configurational assignments are based duced from microanalytical and spectral evidence. The IR
on the assumption that the olefinic protons of the Z-con- spectra of 3 are devoid of any C=O absorption and the 1H
figurated isomers are more deshielded as compared with NMR spectra show neither the AMX pattern of 1 nor the
the E-counterparts. This relationship is an accepted as- olefinic proton of 2. Compounds 3 show molecular ion
sumption in the elucidation of configuration of arylidene peaks as base peaks except 3h where the [R.+] fragment
derivatives of many heterocycles.17
presents the base peak (Table). The abundant fragments
[R.+] and [M.+-R] could be produced through the cleavage
presented in pathway i. Although, formation of the frag-
Thus, thionation of 1a h and (E,Z)-2f, g with tetraphos-
phorous decasulfide or Lawesson’s reagent in xylene for
Table EI-MS Data of 5-Substituted 3-Aryl-2,3-dihydro-2-thioxothieno[2,3-d]thiazoles 3a−h
Compound
Fragments m/z (%)
[M].+
[A].+
[B].+
[C].+
[D].+
R.+
77 (57.8)
3a
3b
3c
3d
3e
325 (100)
339 (100)
331 (100)
345 (100)
248 (16.5)
262 (14.8)
254 (23.8)
254 (14.2)
249 (10.5)
263 (13.4)
255 (12.6)
269 (8.9)
146 (50.9)
160 (38.9)
152 (40.8)
152 (31.2)
102 (28.3)
116 (12.9)
108 (35.5)
108 (23.7)
77 (35.7)
77 (53)
91 (25.1)
91 (58.5)
417 (88.1)
419 (100)a
326 (5.8)
328 (6.6)a
341 (3.6)
343 (3.9)a
224 (18.2)
226 (17.9)a
180 (7.6)
182 (7.3)a
3f
353 (100)
262 (16.4)
262 (37.1)
277 (5)
160 (31.3)
160 (57.5)
116 (11.7)
116 (28.9)
91 (31.6)
3g
373 (100)
279 (2.8)
111 (36.2)
113 (16.4)a
375 (53.5)a
3h
417 (8.5)
419 (8.8)a
326 (14.0)
328 (14.1)a
341 (3.5)
224 (20.3)
226 (20.5)a
180
91 (100)
343 (3.47)a
182a
a M.++ 2 peaks.
Synthesis 2001, No. 3, 413–418 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
A One-Pot Synthesis of 2,3-Dihydro-2-Thioxothieno[2,3-d]Thiazoles
415
Conversion of compounds 1 and 2 into thiophenes 3
Scheme 3
ment [C.+] could be rationalized in terms of the cleavage respective thiophenes21 by heat, the successful conversion
presented in pathway ii, formation via pathway iii is not of 2f, g into fair yields of the respective 3 along with oily
excluded as fragments [B.+], although less abundant, are mixtures containing sulfur, shed doubt on this assump-
recorded in most examples. The pathways i iii are pre- tion, as the 1,4-dithioxo derivatives 5, which are believed
sented in Scheme 2.
to be first formed, are unable to exist in the dienedithiol
form 4‘. Taking into consideration the recent advances in
the chemistry of 1,2-dithiines, where a sulfur atom is eas-
ily extruded either in solutions under mild conditions or
under condition of the mass spectroscopic fragmentation
It has been postulated that the conversion of 1, into the re-
spective thienothiazoles 3 upon treating with tetraphos-
phorous decasulfide or with Lawesson’s reagent has
occurred via the 1,4-dithiono derivatives 4 as sulfurization
of amido and enolizable carbonyl groups is well docu-
to produce thiophenes,21 the conversion of 4
thiazolo-
dithiines 6 3 seems probable. The conversion 4 6 has
occurred, most likely, via a dehydrogenative single elec-
tron cyclization step.
mented.18 20 Although, the conversion 4
3 through the
dienedithiol 4‘ seems to be reasonable in terms of the ease
conversion of (Z,Z)-buta-1,3-diene-1,4-dithiols into the
A possible route for the sulfur extrusion from 6
Scheme 4
Synthesis 2001, No. 3, 413–418 ISSN 0039-7881 © Thieme Stuttgart · New York

416
M. T. Omar et al.
PAPER
Anal. calcd for C18H15NO2S2 (341.4): C, 63.32; H, 4.43; N, 4.10.
Found: C, 63.39; H, 4.23; N, 3.85.
The predominance of 6 versus the ring opened form 5
seems comparable with the preference of the enethiols 4‘
versus the butane-1,4-dithiones 4.
3-Phenyl-5-[2-(thien-2-yl)-2-oxoethyl]-4-oxo-2-thioxo-1,3-thia-
zolidine (1c)
Yield: 2.9 g (87%); mp 130 132 C (toluene/MeOH).
Conversion of (E,Z)-2 into fair yields of 3 could be ratio-
nalized in terms of the configuration around the exocyclic
double bond as only the E-isomers have the proper orien-
tation to cyclize to 6 which is then converted into 3. This
is manifested experimentally in the relative higher yield of
3f as compared with 3g as the E-isomers constitute 50%
and 21% of the E,Z-mixtures of 2f and 2g, respectively.
IR: = 3040 ( CH=CH arom), 2950, 2900 (CH), 1740, 1660 (C=O),
1
1220 (C=S), 750, 690 cm .
1H NMR:
7.775 (dd, 1 H, H-3’, J3’-4’ = 5.0, J3’-5’ = 1.0 Hz), 7.775
(dd, 1 H, H-5’, J4’-5’ = 3.5, J3’-5’ = 1.0 Hz), 7.47 7.62 (m, 3 H, C6H5),
7.288 (dd, 2 H, C6H5, J = 7.8, 1.8 Hz), 7.18 (dd, 1 H, H-4’,
J3’-4’ = 5.0, J4’-5’ = 3.5 Hz), 4.76 (dd, 1 H, HA, JAM = 9.28, JAX = 4.10
Hz), 4.05 (dd, 1 H, HM, JMX = 18, JAM = 9.28 Hz), 3.71 (dd, 1 H, Hx,
JMX = 18.0, JAX = 4.10 Hz).
A rationalization for the sulfur extrusion from 6 is repre-
sented in Scheme 4, in which the ring opened valence iso-
mer 5 undergoes, in the twisted form 7, an intramolecular
Anal. calcd for C15H11NO2S3 (333.4): C, 54.03; H, 3.73; N, 4.2).
Found: C, 54.23; H, 3.43; N, 4.20.
4
2
[ + ] cycloaddition to the episulfide in an irreversible
final step. This stabilization process parallels the sulfur
extrusion in thiepene via thianorcaradien.22 Successful
isolation of episulfides has been reported upon short irra-
diation of dithiines with visible light at 70 C.23
3-(4-Methylphenyl)-5-[2-(thien-2yl)-2-oxoethyl]-4-oxo-2-
thioxo-1,3-thiazolidine (1d)
Yield: 2.7 g (78%); mp 141 143 C (toluene/MeOH).
IR: = 3070 ( CH=CH arom), 2960, 2900, 2850 (CH), 1735, 1660
1
(C=O), 1225 (C=S), 840 cm .
In summary, the method presented represents a new mild,
simple and convenient one pot synthesis of a variety of
3,5-disubstituted-2,3-dihydrothieno[2,3-d]thiazoles 3 in-
cluding alkyl-, aryl- and heteryl-substitutents from the
readily accessible, well crystalline compounds namely
5-(2-aryl-2-oxoethyl)-4-oxo-2-thioxo-1,3-thiazolidines 1.
The synthesis provides also an easy route to the fused
bithienyls 3c, d of anticipated nematocidal activity.24
1H NMR: = 7.769 (dd, 1 H, H-5’, J4’-5’ = 3.8, J3’-5’ = 1.0 Hz), 7.737
(dd, 1 H, H-3’, J3’-4’ = 5.0, J3’-5’ = 1.0 Hz), 7.352, 7.163 (2 d, each 2
H
arom, J = 8.0 Hz), 7.181 (dd, 1 H, H-4‘, J3’-4’ = 5.0, J4’-5’ = 3.8 Hz),
4.731 (dd, 1 H, HA, JAX = 9.2, JAM = 3.2 Hz), 4.047 (dd, 1 H, HM,
MX = 18.2, JAM = 3.2 Hz), 3.697 (dd, 1 H, HX, JMX = 18.2, JAX = 9.2
J
Hz), 2.424 (s, 3 H, CH3).
Anal. calcd for C16H13NO2S3 (347.5): C, 55.31; H, 3.77; N, 4.04.
Found: C, 55.15; H, 3.65; N, 4.05.
3-(4-Methylphenyl)-5-[2-(4-bromophenyl)-2-oxoethyl]-4-oxo-2-
thioxo-1,3-thiazo-lidine (1e)
Yield: 3.65 (87%); mp 160 162 C [CHCl3/light petroleum (bp
60 80 ºC)].
All melting points are not corrected. IR spectra were measured on a
Unicam SP1200 Spectrometer as KBr discs. Unless otherwise stat-
ed, the 1H NMR spectra were measured in CDCl3 on Varian Gemini
200 MHz instrument with chemical shifts ( ) expressed in ppm
downfield from TMS. Mass spectra were recorded on Shimadzu
GC-MS-QP1000EX Instrument operating at 70 eV. Chromatogra-
phy was carried out with Reidel-de Haen Silica gel S 0.063 0.1 mm
on a column with the following dimensions: length = 17 cm and
diameter = 1.7 cm. TLC was performed on Merk Kieselgel 60 F254
aluminium backed plates. 3-Phenyl-5-(2-phenyl-2-oxoethyl)-4-
oxo-2-thioxo-1,3-thiazolidine (1a) and 3-benzyl-5-[2-(4-bro-
mophenyl)-2-oxoethyl]-4-oxo-2-thioxo-1,3-thiazolidine (1h) were
synthesized according to reported methods.25
IR: = 3050 ( CH=CH arom), 2940, 2920, 2880 (CH), 1735, 1680,
1
(C=O), 1235 (C=S), 830 cm .
1H NMR: = 7.84, 7.658 (2 d, each 2 Harom, J = 8.8 Hz), 7.36, 7.16
(2 d, each 2 Harom, J = 8.2 Hz), 4.745 (dd, 1 H, HA, JAM = 9.4,
JAX = 3.2 Hz), 4.09 (dd, 1 H, HM, JMX = 18.6, JAM = 9.4 Hz), 3.705
(dd, 1 H, HX, JMX = 18.6, JAX = 3.2 Hz), 2.405 (s, 3 H, CH3).
Anal. calcd for C18H14BrNO2S2 (420.3): C, 51.43; H, 3.36; N, 3.33.
Found: C, 51.60; H, 3.35; N, 3.37.
3-(4-Methylphenyl)-5-[2-(4-methylphenyl)-2-oxoethyl]-4-oxo-
2-thioxo-1,3-thiazo-lidine (1f)
Yield: 3.1 g (87%); mp 143 145 C (toluene/MeOH).
3-Aryl-5-(2-Aryl-2-oxoethyl)-4-oxo-2-thioxo-1,3-thiazolidines
1b-g; General Procedure
Ammonium aryldithiocarbamate (10.0 mmol) was added portion-
wise to a stirred solution of the respective 3-aroylprop-2-enoic
acid26 in EtOH (10.0 mL) and the mixture was stirred for 30 min at
r.t. The solid precipitated after addition of concd HCl (3 mL) and
boiling (5 min) was filtered off, washed several times with cold
H2O, air dried and recrystallized from the proper solvent to give co-
lourless crystals of the title compounds.
IR: = 3020 ( CH=CH arom), 2930, 2910 (CH), 1740, 1680,
(C=O), 1240 (C=S), 810 cm .
1
1H NMR:
7.87 (d, 2 Harom, J = 8.4 Hz), 7.28, 7.37 (two central
peaks of ABq, 4 Harom), 7.2 (d, 2 Harom, J = 8.4 Hz), 4.735 (dd, 1 H,
HA, JAM = 9.6, JAX = 3.2 Hz), 4.15 (dd, 1 H, HM, JMX = 18.4,
JAM = 9.6 Hz), 3.75 (dd, 1 H, HX, JMX = 18.4, JAX = 3.2), 2.44, 2.425
(2 s, each 3 H, CH3).
3-Phenyl-5-[2-(4-methylphenyl)-2-oxoethyl]-4-oxo-2-thioxo-
1,3-thiazolidine (1b)
Yield: 3.0 g (88%); mp 158 160 C (toluene/MeOH).
Anal. calcd for C19H17NO2S2 (355.5): C, 64.20; H, 4.82; N, 3.94.
Found: C, 63.82; H, 4.25; N, 4.20.
3-(4-Chlorophenyl)-5-[2-(4-methylphenyl)-2-oxoethyl]-4-oxo-
2-thioxo-1,3-thiazolidine (1g)
Yield: 3.25 g (87%); mp 160 162 C (benzene/MeOH).
IR: = 3050 ( CH=CH arom), 2950, 2920, 2860 (CH), 1735, 1680
(C=O), 1235 (C=S), 810, 750, 700 cm .
1
1H NMR:
C6H5), 7.45 7.277 (m, 4 H, Harom), 4.742 (dd, 1 H, HA, JAM = 9.6,
AX = 3.2 Hz), 4.107 (dd, 1 H, HM, JMX = 18.6, JAM = 9.6 Hz), 3.72
(dd, 1 H, Hx, JMX = 18.6, JAX = 3.2 Hz), 2.43 (s, 3 H, CH3).
7.872 (d, 2 H, Harom, J = 8.4 Hz), 7.62 7.53 (m, 3 H,
IR: = 3050 ( CH=CH arom), 2940, 2910, 2860 (CH), 1725, 1675,
1
(C=O), 1225 (C=S), 815 cm .
J
1H.NMR:
(2 d, each 2 Harom, J = 8.6 Hz), 4.731 (dd, 1 H, HA, JAM = 9.2,
7.87, 7.305 (2 d, each 2 Harom, J = 8.2 Hz), 7.52, 7.25
Synthesis 2001, No. 3, 413–418 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
A One-Pot Synthesis of 2,3-Dihydro-2-Thioxothieno[2,3-d]Thiazoles
417
1
JAX = 3.0 Hz), 4.09 (dd, 1 H, HM, JMX = 18.6, JAM = 9.2 Hz), 3.74
(dd, 1 H, HX, JMX = 18.6, JAX = 3.0 Hz), 2.44 (s, 3 H, Me).
IR: = 3080 3000 (CH=CHarom), 1200 (C=S), 800, 750, 700 cm .
1H NMR:
7.70 7.57 (m, 5 H, C6H5), 7.40, 7.215 (2 d, each 2
Anal. calcd for C18H14ClNO2S2 (375.9): C, 57.52; H, 3.75; N, 3.73.
Found: C, 57.35; H, 3.725; N, 3.65.
Harom, J = 8.0 Hz), 7.145 (s, 1 H, H-6), 2.395 (s, 3 H, CH3).
Anal. calcd C18H13NS3 (339.5): C, 63.68; H, 3.86; N, 4.13. Found:
C, 63.64; H, 3.71; N, 4.20.
(E,Z)-3-Aryl-5-(2-aryl-2-oxoethylidene)-4-oxo-2-thioxo-1,3-thi-
azolidines 2f and 2g
3-Phenyl-5-(2-thienyl)-2,3-dihydro-2-thioxothieno[2,3-d]thiaz-
ole (3c)
Yield: 2.9 g (88%, Method A), 3.15 g (95%, Method B); mp 161
163 C.
A mixture of 1f or 1g (3.0 mmol) and Br2 (3.1 mmol) in glacial
AcOH (50 mL) was armed gently for 5 min, during which time HBr
gas ceased to evolve. The reaction mixture was concentrated
(10 mL), poured into cold H2O (100 mL) and the precipitated or-
ange-yellow product was filtered off, washed successively with
cold H2O, air dried and recrystallized once from the proper solvent
to give (E,Z)-2 as orange crystals.
IR: = 3080 3000 (CH=CH arom), 1200 (C=S), 800, 750, 700
1
cm .
1H NMR: = 7.7 7.5 (m, 5 H, C6H5), 7.255 (dd, 1 H, H-5’,
J4’-5’ = 4.8, J3’-5’ = 0.6 Hz), 7.033 (s, 1 H, H-6), 7.01 (dd, 1 H, H-4’,
(E,Z)-3-(4-Methylphenyl)-5-[2-(4-methylphenyl)-2-oxoeth-
ylidene]-4-oxo-2-thioxo-1,3-thiazolidine (2f)
Yield: 3.4 g (96%); mp 220 222 C [CHCl3/light petroleum (bp
40 60 C]
J4’-5’ = 4.8, J3’-4’ = 3.8 Hz), 6.98 (dd, 1 H, H-3’, J3’-4’ = 3.8, J3’-5’ = 0.6
Hz).
Anal. calcd for C15H9NS4 (331.5): C, 54.35; H, 2.74; N, 4.23.
Found: C, 54.31; H, 2.79; N, 4.21.
IR: = 3060 (CH=CH arom), 1730 (br), 1680 (C=O), 1225 (C=S),
822 cm .
1H NMR (DMSO-d6): = 7.18 7.50 (m, 6 Harom), 2.395 2.43 each
(s, 3 H, CH3). E-isomer (65%): 8.16, (d, 2 Harom, J = 8.4 Hz), 8.125
(s, 1 H, =CH). Z-isomer (35%): 7.915 (d, 2 Harom, J = 8.4 Hz), 8.25
(s, 1 H, =CH).
3-(4-Methylphenyl)-5-(2-thienyl)-2,3-dihydro-2-thioxothieno
[2,3-d] thiazole (3d)
Yield: 3.0 g (87%, Method A), 3.15 g (91%, Mehod B); mp 190
192 C.
1
1
IR: = 3080 3000 (CH=CH arom), 1200 (C=S), 800 cm .
1H NMR: = 7.44, 7.43 (two central peaks of ABq, 4 Harom), 7.25
(dd, 1 H, H-5’, J4’-5’ = 5.0, J3’-5’ = 1.2 Hz), 7.08 (dd, 1 H, H-3’,
J3’-4’ = 3.4, J3’-5’ = 1.2 Hz), 7.035 (s, 1 H, H-6), 7.01 (dd, 1 H, H-4’,
Anal. calcd C19H15NO2S2 (353.0): C, 64.57; H, 4.28; N, 3.96.
Found: C, 64.42; H, 4.15; N, 3.72.
(E,Z)-3-(4-Chlorophenyl)-5-[2-(4-methylpheny)-2-oxoeth-
ylidene]-4-oxo-2-thioxo-1,3-thiazolidine (2g)
Yield: 3.55 g (95%); mp 282 284 C (dioxane-toluene).
J
4’-5’ = 5.0, J3’-4’ = 3.4 Hz), 2.36 (s, 3 H, CH3).
Anal. calcd for C16H11NS4 (345.5): C, 55.62; H, 3.21; N, 4.05.
Found: C, 55.42; H, 2.93; N, 4.29.
IR: = 3080 (CH=CH arom), 1725 (br), 1675 (C=O), 1220 (C=S),
830 cm .
1H NMR: = 7.32 7.54 (m, 4 Harom), 2.40 (s, 3 H, CH3). E-isomer
(20%): 8.415, 7.815 (2 d, each 2 Harom, J = 8.8 Hz), 8.01 (s, 1 H,
=CH ). Z-isomer (79%): 8.28, 7.69 (2 d, each 2 Harom, J = 8.4Hz),
8.14 (s, 1 H, =CH).
3-(4-Methylphenyl)-5-(4-bromophenyl)-2,3-dihydro-2-
thioxothieno[2,3-d]thiazole (3e)
Yield: 3.7 g (89%, Method A), 3.9 g (93%, Method B); mp 190 192
°C.
1
1
IR: = 3080 3000 (CH=CH arom), 1200 (C=S), 800 cm .
1H NMR: = 7.58 (central peak of ABq, 4 Harom), 7.38, 7.20 (2 d,
each 2 Harom, J = 7.8 Hz), 7.125 (s, 1 H, H-6), 2.37 (s, 3, CH3).
Anal. calcd for C18H12ClNO2S2 (373.5): C, 57.83; H, 3.24; N, 3.75.
Found: C, 57.58; H, 3.35; N, 3.75.
Anal. calcd for C18H12BrNS3 requires: C, 51.57; H, 2.89; N, 3.35.
Found: C, 51.75; H, 3.00; N, 3.52.
3,5-Disubstituted 2,3-Dihydro-2-thioxothieno[2,3-d]thiazoles
3a h (Methods A and B)
3,5-Di-(4-Methylphenyl)-2,3-dihydro-2-thioxothieno[2,3-d]thi-
A mixture of each of 1a h (3.0 mmol) and finely powdered tetra-
phosphorous decasulfide (0.2 g, 0.45 mmol) (Method A) or Lawes-
son’s reagent27,28 (1.1 g, 2.7 mmol) (Method B) was refluxed in
xylene (25 mL) for 4 h and then poured into H2O (50 mL). The or-
ganic layer was separated, washed successively with H2O, dried
(CaCl2), concentrated (3 mL) and diluted with MeOH (5 mL). The
precipitated solid was filtered off, air dried and recrystallized from
toluene/MeOH to offer colourless crystals of the title compounds.
azole (3f)
Yield: 3.0 g (85%, Method A), 3.2 g (91%, Method B); mp 176 178
C.
IR: = 3030 (CH=CH arom), 1200 (C=S), 800 cm .
1H NMR:
7.14 (2 d, each 2 Harom, J = 8.0 Hz), 7.11 (s, 1 H, H-6), 2.46, 2.36
(2 s, each 3 H, Me).
7.45, 7.43 (two central peaks of ABq, 4 Harom), 7.37,
Anal. calcd for C19H15NS3 (353.5): C, 64.55; H, 4.28; N, 3.96.
Found: C, 64.51; H, 4.21; N, 3.99.
3,5-Diphenyl-2,3-dihydro-2-thioxothieno[2,3-d]thiazole (3a)
Yield: 2.55 g (79%, Method A), 3.0 g (92%, Method B); mp 163
165 C.
3-(4-Chlorophenyl)-5-(4-methylphenyl)-2,3-dihydro-2-
thioxothieno[2,3-d]thiazole (3 g)
Yield: 3.15 g (85%, Method A) 3.3 g (89%, Method B), mp 182
184 C.
1
IR: = 3080 3000 (CH=CH arom), 1200 (C=S), 750, 700 cm .
1H NMR: = 7.67 7.53 (m, 5 H, C6H5), 7.54 7.253 (m, 5 H, C6H5),
7.167 (s, 1 H, H-6).
1
IR: = 3070 (CH=CH, arom), 1200 (C=S), 790 cm .
Anal. calcd for C17H11NS (325.5): C, 62.74; H, 3.41; N, 4.30.
Found: C, 62.75; H, 3.375; N, 4.29.
1H NMR: = 7.505, 7.34 each (2 d, each 2 Harom, J = 8.6 Hz), 7.44,
7.43 (two central peaks of ABq, 4 Harom), 7.16 (s, 1 H, H-6), 2.485
(s, 3 H, CH3).
3-Phenyl-5-(4-methylphenyl)-2,3-dihydro-2-thioxothieno[2,3-
d]thiazole (3b)
Yield: 2.95 g (87%, Method A), 3.1 g (91.45%, Method B); mp
163 165 C.
Anal. calcd for C18H12ClNS3 (373.9): C, 57.82; H, 3.23; N, 3.75.
Found: C, 57.78; H, 3.315; N, 3.87.
Synthesis 2001, No. 3, 413–418 ISSN 0039-7881 © Thieme Stuttgart · New York

418
M. T. Omar et al.
PAPER
(8) Astrakhantseva, N. I.; Zhiryakov, V. G.; Abramenko, P. I.
3-Benzyl-5-(4-bromophenyl)-2,3-dihydro-2-thioxothieno[2,3-
d]thiazole (3h)
Chem. Heterocycl. Compd. (Engl. Transl.) 1976, 12, 1123.
(9) Abramenko, P. I.; Ponomareva, T. K.; Priklonskikh, G. I. Zh.
Vses. Khim. Ova 1978, 23, 711; Chem. Abstr. 1979, 90,
152060.
(10) Abramenko, P.I.; Ponomareva, T. K.; Prinklonskikh, G. I.
Chem. Heterocycl. Compd. (Engl. Transl.) 1979, 15, 387.
(11) Gosie Senryo Gijutsu Kenkyu Kumiai, Jpn. Kokai Tokkyo
Koho, Jap. P 58 38 756 (1983); Chem. Abstr. 1983, 99,
106766.
Yield: 3.69g (86%), Method A), 3.75 g (90%, Method B), mp 182
184 C.
1
IR: = 3060 3030 (CH=CHarom), 1200 (C=S), 810, 750, 700 cm .
1H NMR:
7.39, 7.37 (two central peaks of ABq 4Harom), 7.40
7.50 (m, 5 H, C6H5), 7.075 (s, 1 H, H-6), 5.53 (s, 2 H, CH2Ph).
Anal. calcd C18H12BrNS3 (418.4): C, 51.67; H, 2.89; N, 3.35.
Found: C, 51.62; H, 2.78; N, 3.33.
(12) Pinkin, L. D.; Dzyubenko, V. G.; Abramenko,P. I.; Shpileva,
I. S. Chem. Heterocycl. Compd. (Engl. Transl.) 1987, 23, 345.
(13) Aoki, H.; Kodera, K.;.Hikasa, M.; Okugawa, T. Jap. Kokai
Tokkyo Koho, Jap. Patent 146 960 (1989); Chem. Abstr. 1989,
111, 235045.
(14) Rezessy, B.; Toldy, L.; Horvath, G.; Sohar, P. Tetrahedron
1991, 47, 10045.
(15) Athmani, S.; Farahat M. F.; Iddon, B. J. Chem. Soc., Perkin
Trans. 1 1992, 937.
(16) Nagase, H. Chem. Pharm. Bull. 1974, 22, 1661.
(17) Baumann, N.; Sung, M.;Uliman, F. J. Am. Chem. Soc.1970,
980.
Dailsley, R. W.; Walker, J. J. Chem. Soc. (C) 1971, 3357.
(18) Vyunov, K. A.; Ginak, A. I.; Sochillin, E. G. Khim.
Geterotzikl. Soedin 1971, 27, 192; Chem. Abstr. 1971, 75,
3583.
(19) Grishchuk, A. P. Khim. Geterotsikl. Soedin. 1966, 372; Chem.
Abstr. 1966, 65 13680.
(20) Kibbel, H. U.; Blodorn, H.; Ketcham, R.; Schaumann, E.
Chem. Ber. 1993, 126, 2079.
Reaction of 2f and 2g with Tetraphosphorous Decasulfide or
Lawesson’s Reagent (Methods C and D)
A mixture of 2f or 2g (3.0 mmol) and finely powdered tetraphos-
phorous decasulfide (0.2 g, 0.45 mmol, Method C) or Lawesson’s
reagent27,28 (1.1 g, 2.7 mmol, Method D) was refluxed in xylene/di-
oxane (25 mL, 5:1 v/v) for 4 h, and then poured into H2O (100 mL).
The reddish brown organic layer was separated, washed successive-
ly with H2O, dried (Na2SO4), concentrated (to 10 mL) and chro-
matographed over silica gel. Elution with light petroleum (bp 60
80 °C)/EtOAc (5:1 v/v) gave first the required thienothiazole 3f and
3g and then the yellow oily mixtures. Separation was monitored by
TLC. Separation and identification of the oily products are still in
progress.
3f
Obtained from 2f; yield: 0.15 g (43%, Method C), 0.17 g, 48%,
Method D); mp 176 178 C (CHCl3/light petroleum (bp 40 60
°C), undepressed on admixture with the sample previously obtained
from Methods A and B.
(21) Schroth, W.; Dunger, S.; Billig, F.; Spitzner, R.; Herzschuh,
R.; Vogt, A.; Jende, T.; Israel, G.; Barche, J.; Strohl, D.; Siele,
J. Tetrahedron 1996, 52, 120.
(22) Murata, I. Phosphorous, Sulfur and Silicon 1989, 43, 243.
(23) Block, E.; Page, J.; Toscano, J. P.; Wang, C. X.;Zhang, X.;
DeOrazio, R.; Guo, C.; Sheridan, R. S.;Towers, G. H. N. J.
Amer. Chem. Soc. 1996, 118, 4719.
(24) Campaigne, E.; White, R. L. J. Heterocycl. Chem. 1988, 25,
367.
(25) Omar, M. T.; Youssef, A. S. A.; Kandeel, K. A. Phosphorus
Sulfur and Silicon 2000, 162, 25.
3g
Obtained from 2g; yield: 0.06 g (16%, Method C), 0.075 g, 20%,
Method D); mp 182 184 °C (dioxane/toluene), undepressed on ad-
mixture with the sample previously obtained from Methods A and
B.
References
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Article Identifier:
1437-210X,E;2001,0,03,0413,0418,ftx,en;Z06800SS.pdf
Synthesis 2001, No. 3, 413–418 ISSN 0039-7881 © Thieme Stuttgart · New York