Oxalylation of the 3-oxo-N-phenyl-3-R-propanethioamides

Article abstract of DOI:10.1007/s11172-005-0318-0

Oxalylation of 3-oxo-N-phenyl-3-R-propanethioamides in aprotic solvents in the temperature range from -40°C to +20°C results in 4-acyl-5-phenylamino-2,3-dihydrothiophene-2,3-diones and 2-(2-oxo-2-R- ethylidene)-3-phenyl-1,3-thiazolidine-4,5-diones, while

Full text of DOI:10.1007/s11172-005-0318-0

770
Russian Chemical Bulletin, International Edition, Vol. 54, No. 3, pp. 770—773, March, 2005
Oxalylation of the 3ꢀоxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamides
ꢀ
V. N. Britsun, A. N. Borisevich, L. S. Samoylenko, A. N. Chernega, and M. O. Lozynskii
Institute of Оrganic Chemistry, National Аcademy of Sciences of Ukraine,
5 ul. Murmanskaya, 02094 Kievꢀ94, Ukraine.
Eꢀmail: esipenko@iflab.kiev.ua
Oxalylation of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamides in aprotic solvents in the temꢀ
perature range from –40°С to +20°С results in 4ꢀacylꢀ5ꢀphenylaminoꢀ2,3ꢀdihydrothiopheneꢀ
2,3ꢀdiones and 2ꢀ(2ꢀоxоꢀ2ꢀRꢀethylidene)ꢀ3ꢀphenylꢀ1,3ꢀthiazolidineꢀ4,5ꢀdiones, while in the
presence of potassium carbonate, potassium 4ꢀacylꢀ2,3ꢀdioxoꢀ1ꢀphenylꢀ2,3ꢀdihydroꢀ1Hꢀpyrꢀ
roleꢀ5ꢀthiolates are formed.
Key words: оxalylation, 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamides, cyclization, ring transꢀ
formation, 5ꢀphenylaminoꢀ4ꢀacylꢀ2,3ꢀdihydrothiopheneꢀ2,3ꢀdiones, 2ꢀ(2ꢀoxoꢀ2ꢀRꢀethylꢀ
idene)ꢀ3ꢀphenylꢀ1,3ꢀthiazolidineꢀ4,5ꢀdiones, potassium 4ꢀacylꢀ2,3ꢀdioxoꢀ1ꢀphenylꢀ2,3ꢀ
dihydroꢀ1Hꢀpyrroleꢀ5ꢀthiolates, 4ꢀacylꢀ1ꢀphenylꢀ5ꢀthioxopyrrolidineꢀ2,3ꢀdiones.
3ꢀOxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamides react with
phenylꢀ3ꢀRꢀpropanethioamides can be acylated by oxalyl
electrophilic reagents as ambident nucleophiles,1,2
which makes them promising starting compounds for
the synthesis of diverse heterocycles such as pyrazoles,3
thiazoles,4 and 1,2,4ꢀdithiazolidines.5 However, the
presence of several reaction centers in 3ꢀoxoꢀNꢀphenylꢀ
3ꢀRꢀpropanethioamides does not always allow one to preꢀ
dict unambiguously the reaction route or reaction selecꢀ
tivity.
The reaction of 3ꢀoxoꢀN,3ꢀdiphenylpropanethioamide
with oxalyl chloride has been reported6,7 to proceed as
[3+2]ꢀcyclocondensation giving rise to 2ꢀ(2ꢀoxoꢀ2ꢀ
phenylethylidene)ꢀ3ꢀphenylꢀ1,3ꢀthiazolidineꢀ4,5ꢀdione
and 4ꢀbenzoylꢀ1ꢀphenylꢀ5ꢀthioxopyrrolidineꢀ2,3ꢀdione,
the yield of each product being 30%. Since 3ꢀoxoꢀNꢀ
chloride at the S atom and the active methylene group,
the formation of 2,3ꢀdihydrothiopheneꢀ2,3ꢀdiones is also
possible. This study deals with the influence of solvents,
compounds of a basic nature, and the temperature condiꢀ
tions on the oxalylation of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropaneꢀ
thioamides and the synthesis of 2,3ꢀdihydrothiopheneꢀ
2,3ꢀdiones.
Since Sꢀacylation is thermodynamically less favorable
than Nꢀacylation,8—10 it appeared reasonable to carry out
oxalylation of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamides
in various aprotic solvents under kinetic control condiꢀ
tions, i.e., at ambient or lower temperatures. The results
of oxalylation of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioꢀ
amides are summarized in Scheme 1 and in Table 1.
Scheme 1
1, 3, 4, 5 : R = Me (a), Ph (b)
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 757—760, March, 2005.
1066ꢀ5285/05/5403ꢀ0770 © 2005 Springer Science+Business Media, Inc.

Oxalylation of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamides Russ.Chem.Bull., Int.Ed., Vol. 54, No. 3, March, 2005
771
Table 1. Effect of the nature of the solvent and the base on the
product ratio in oxalylation of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀ
propanethioamides 1a and 1b
Scheme 2
Run*
Solvent
3a 4a 5a 3b 4b 5b
1
2
3**
4
Tetrachloromethane 1.0 1.1
—
—
—
—
1.0 1.2
1.0 1.6
1.0 0.4
1.0 1.9
—
—
Chloroform
Chloroform
Chloroform +
N,Nꢀdimethylꢀ
aniline
1.0 1.0
1.0 0.3
1.0 2.0
—
idineꢀ4,5ꢀdione 4a. It was found that, unlike the deꢀ
scribed 4b, these compounds do not change on refluxing
in hydrogen chlorideꢀcontaining dioxane (2 h) or 1,3ꢀdiꢀ
chlorobenzene (1 h). However, stirring of a solution of
thiopheneꢀ2,3ꢀdione 3a in acetone in the presence of
К2СО3 at 20 °С results in ring transformation of 3a to give
potassium 2,3ꢀdioxopyrroleꢀ5ꢀthiolate 5a in 57% yield
(after 1 h) or in 85% yield (after 3 h). Similarly, on treatꢀ
ment with К2СО3 in acetone, 1,3ꢀthiazolidineꢀ4,5ꢀdione
4a is converted into potassium thiolate 5a. In all probabilꢀ
ity, the ring transformations in thiopheneꢀ2,3ꢀdiones 3a,b
and thiazolidineꢀ4,5ꢀdiones 4b to give pyrroleꢀ2,3ꢀdiones
5a,b are due to the low stability of the S—С=О bond.9,10
Since the 1H NMR signals of the NH protons
of thiopheneꢀ2,3ꢀdiones 3a,b and the OH protons
of 5ꢀthioxopyrrolidineꢀ2,3ꢀdiones 6a,b are close
(13.65—13.67 and 14.62—15.25, respectively), for unamꢀ
biguous identification of compounds 3a,b and 6a,b, we
studied thiopheneꢀ2,3ꢀdione 3a by Xꢀray diffraction.
The general view and selected geometric parameters
of molecule 3a are shown in Fig. 1. The thiophene ring is
planar (the deviations of atoms from the rootꢀmeanꢀsquare
plane do not exceed 0.008 Å), the amine fragment,
C(1)N(1)H(1)C(7), lying virtually in this plane (the corꢀ
responding dihedral angle is only 2.0°). The benzene ring
forms a dihedral angle of 65.0° with the thiophene ring.
The N(1) atom has a planar trigonal configuration, the
sum of the bond angles at this atom being 359.9°. The
effective conjugation of the lone pair of N(1) with the
thiophene ring results in a substantial shortening of
the N(1)—C(1) bond (1.313(2) Å) with respect to the
1.43—1.45 Å value typical of a single N(sp2)—C(sp2) bond.
A characteristic feature of the molecular structure of comꢀ
pound 3a is the formation of rather strong11 intramolecuꢀ
lar hydrogen bond, N(1)—H(1)...О(3), which becomes
even stronger "due to the resonance."12 The geometric
parameters of this Hꢀbond are as follows: N...О, 2.649(2);
N—H, 0.87(2); О...H, 1.96(2) Å; N—H—N, 136(1)°.
Thus, it was shown that oxalylation of 3ꢀoxoꢀNꢀpheꢀ
nylꢀ3ꢀRꢀpropanethioamides in aprotic solvents in the
temperature range from –40 °С to +20 °С results in kiꢀ
netically controlled products, 5ꢀphenylaminoꢀ4ꢀacylꢀ
2,3ꢀdihydrothiopheneꢀ2,3ꢀdiones and 2ꢀ(2ꢀoxoꢀ2ꢀRꢀ
ethylidene)ꢀ3ꢀphenylꢀ1,3ꢀthiazolidineꢀ4,5ꢀdiones, while
oxalylation in the presence of potassium carbonate yields
5
6
Diethyl ether
Diethyl ether +
N,Nꢀdimethylꢀ
aniline
Diethyl ether +
К2СО3
1.0 1.4
1.0 1.7
—
—
1.0 0.9
1.0 1.5
—
—
7
1.0 0.4 3.3 1.0 1.3 4.1
8
9
10
Dioxane
Acetone
1.0 0.7
1.0 1.0
—
—
1.0 0.4
1.0 0.6
—
—
Acetone + К2СО3 1.0 0.3 3.0 1.0 1.2 3.4
* The reaction time is 1 h, T ≈ 20 °С.
** The reaction time is 10 h, T = –40 °С.
We found that, unlike oxalylation in boiling dioxane
for 3 h,6,7 the reaction of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropaneꢀ
thioamides 1a,b with oxalyl chloride carried out for 1 h at
20 °С in aprotic solvents of different polarity affords the
products of acylation at the S atom and the active methylꢀ
ene group, namely, 4ꢀacylꢀ5ꢀphenylaminoꢀ2,3ꢀdihydroꢀ
thiopheneꢀ2,3ꢀdiones (3a,b), and the oxalylation prodꢀ
ucts at the S and N atoms, namely, 2ꢀ(2ꢀoxoꢀ2ꢀRꢀ
ethylidene)ꢀ3ꢀphenylꢀ1,3ꢀthiazolidineꢀ4,5ꢀdiones 4a,b.
The nature of the solvent has little influence on the ratio
of the reaction products, which are formed in approxiꢀ
mately equal amounts (see Table 1, runs 1, 2, 5, 8, 9). The
oxalylation of 1a,b at –40 °С results in a mixture of 3a,b
and 4a,b in which thiopheneꢀ2,3ꢀdiones 3a,b predomiꢀ
nate (run 3). The acylation of propanethioamides 1a,b in
chloroform and diethyl ether in the presence of N,Nꢀdiꢀ
methylaniline yields a mixture of compounds 3a,b and
4a,b in which thiazolidineꢀ4,5ꢀdiones 4a,b are the major
components (runs 4 and 6), whereas oxalylation of 1a,b in
diethyl ether or acetone in the presence of К2СО3 affords
mainly potassium 4ꢀacylꢀ2,3ꢀdioxoꢀ1ꢀphenylꢀ2,3ꢀdiꢀ
hydroꢀ1Hꢀpyrroleꢀ5ꢀthiolates 5a,b, together with thioꢀ
pheneꢀ2,3ꢀdiones 3a,b and thiazolidineꢀ4,5ꢀdiones 4a,b
(runs 7 and 10). Compounds 5a,b were converted into
4ꢀacylꢀ1ꢀphenylꢀ5ꢀthioxopyrrolidineꢀ2,3ꢀdiones 6a,b on
treatment with hydrochloric acid (Scheme 2).
It has been reported previously6 that 1,3ꢀthiazolidineꢀ
4,5ꢀdione 4b is a thermodynamically unstable compound
and, on refluxing in a dioxane—hydrochloric acid mixture
for 2 h, it is converted into pyrrolidineꢀ2,3ꢀdione 6b in
10% yield. Therefore, we studied the thermal and chemiꢀ
cal stability of thiopheneꢀ2,3ꢀdione 3a and 1,3ꢀthiazolꢀ

772
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 3, March, 2005
Britsun et al.
Oxalylation of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamides (genꢀ
eral procedure). Oxalyl chloride 2 (10.5 mmol) in 3 mL of a
solvent was added dropwise with stirring to a solution of 3ꢀoxoꢀ
Nꢀphenylꢀ3ꢀRꢀpropanethioamide 1a,b (10 mmol) in 10 mL of
the solvent. The reaction mixture was kept for 0.5 h at 20 °C and
the solvent was evaporated. The product ratio was determined
C(9)
C(10)
C(8)
O(3)
H(1)
N(1)
C(11)
C(5)
C(7)
1
by H NMR, the integration accuracy being 5%.
C(12)
4ꢀAcetylꢀ5ꢀphenylaminoꢀ2,3ꢀdihydrothiopheneꢀ2,3ꢀdione
(3a) and 4ꢀbenzoylꢀ5ꢀphenylaminoꢀ2,3ꢀdihydrothiopheneꢀ2,3ꢀ
dione (3b). A solution of oxalyl chloride 2 (1.33 g, 10.5 mmol) in
3 mL of chloroform was added dropwise with stirring over a
period of 0.5 h to a solution of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropaneꢀ
thioamide 1a,b (10 mmol) in 10 mL of chloroform at –40 °C.
The reaction mixture was kept for 9.5 h at –40 °C, chloroform
was evaporated, and the crystals that formed were recrystallized
from acetic acid (3a) or twice recrystallized from toluene (3b).
Yield 3a 1.48 g (60%), m.p. 180—182 °C. Found (%): C, 58.42;
H, 3.56; N, 5.64; S, 12.83. C12H9NO3S. Calculated (%):
C, 58.29; H, 3.67; N, 5.66; S, 12.97. 1H NMR (CDCl3), δ: 2.62
(s, MeCO); 7.33—7.48 (m, Ph); 13.65 (br.s, NH). 13C NMR
(DMSOꢀd6), δ: 23.9 (Me); 110.6 (N—C=S); 127.6, 128.3, 128.9,
133.3, 160.8, 176.5, 187.1, 198.0 (MeCO). IR, ν/cm–1: 3050
(Ph); 1760 (C=O); 1710 (C=O); 1620 (C=O); 1430, 1360, 1330.
Yield 3b 1.33 g (43%), m.p. 191—193 °C. Found (%): C, 65.81;
H, 3.44; N, 4.67; S, 10.08. C17H11NO3S. Calculated (%):
C, 66.01; H, 3.58; N, 4.53; S, 10.36. 1H NMR (CDCl3), δ:
7.41—7.77 (m, 2 Ph); 13.67 (br.s, NH). IR, ν/cm–1: 3100 (Ph);
1750 (C=O); 1700 (C=O); 1630 (C=O); 1590, 1420.
C(1)
C(6)
C(2)
S(1)
C(3)
O(2)
C(4)
O(1)
Fig. 1. General view of molecule 3a. Selected bond lengths (Å):
S(1)—C(1), 1.765(2); S(1)—C(4), 1.801(2); C(1)—C(2),
1.407(2); C(2)—C(3), 1.423(2); C(3)—C(4), 1.553(3); and bond
angles (deg): N(1)—C(1), 1.313(2); N(1)—C(7), 1.434(2);
C(1)—S(1)—C(4), 121.6(1); C(1)—N(1)—C(6), 89.68(8).
predominantly thermodynamically controlled potassium
4ꢀacylꢀ2,3ꢀdioxoꢀ1ꢀphenylꢀ2,3ꢀdihydroꢀ1Hꢀpyrroleꢀ5ꢀ
thiolate.
Experimental
2ꢀAcetonylideneꢀ3ꢀphenylꢀ1,3ꢀthiazolidineꢀ4,5ꢀdione (4a) and
2ꢀ(2ꢀoxoꢀ2ꢀphenylethylidene)ꢀ3ꢀphenylꢀ1,3ꢀthiazolidineꢀ4,5ꢀ
dione (4b). A solution of oxalyl chloride (1.33 g, 10.5 mmol) in
3 mL of chloroform was added dropwise with stirring at 20 °C
over a period of 0.5 h to a solution of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀ
propanethioamide 1a,b (10 mmol) and N,Nꢀdimethylaniline
(3.03 g, 25 mmol) in 10 mL of chloroform. The reaction mixture
was kept for 0.5 h and washed with 20 mL of 10% HCl and the
chloroform layer was separated, dried with MgSO4, and conꢀ
centrated. The crystals that formed were recrystallized from
1,3ꢀdichlorobenzene. Yield 4a 1.28 g (52%), m.p. 179—181 °C.
Found (%): C, 58.12; H, 3.80; N, 5.53; S, 13.19. C12H9NO3S.
NMR spectra were recorded on a Varianꢀ300 instrument
operating at 300 МHz (1H) or 75 МHz (13C) in DMSOꢀd6 or
CDCl3 with Me4Si as the internal standard. IR spectra were
measured on a URꢀ20 instrument in КВr pellets.
XꢀRay diffraction of compound 3a. The single crystals of
compound 3a were prepared by slow crystallization from
CH3COOH. The Xꢀray diffraction experiment was carried out
for a crystal with the linear dimensions 0.37×0.40×0.47 mm at
room temperature on a CADꢀ4 Enraf—Nonius automated fourꢀ
circle diffractometer (CuꢀКα radiation, λ = 1.54178 Å, scanꢀ
ning rate ratio 2θ/ω 1.2, θmax = 69°). Altogether 4181 reflections
were collected, 1874 of which were symmetrically independent
(Rint = 0.026). The crystals of compound 3a are monoclinic,
a = 23.195(3), b = 5.678(1), c = 19.527(2) Å, β = 120.47(1)°,
1
Calculated (%): C, 58.29; H, 3.67; N, 5.66; S, 12.97. H NMR
(DMSOꢀd6), δ: 2.15 (s, MeCO); 5.81 (s, CO—CH=); 7.44—7.62
(m, Ph). 13C NMR (DMSOꢀd6), δ: 30.9 (Me); 104.2 (N—C=S);
127.9, 130.0, 134.4, 145.8, 156.0, 185.0, 196.9 (MeCO). IR,
ν/cm–1
: 3100 (Ph); 1745 (C=O); 1690 (C=O); 1600
V = 2214.6(9) Å3, C12H9NO3S, M = 247.3, Z = 8, dcalc
=
1.48 g cm–3, µ = 25.78 cm–1, F(000) = 1024.0, space group C2/c
(No. 15). The structure was solved by the direct method and
refined by least squares in the fullꢀmatrix anisotropic approxiꢀ
mation using the CRYSTALS software.13 The refinement inꢀ
cluded 1731 reflections with I > 3σ(I ) (190 refined parameters,
the number of reflections per parameter 9.1). All hydrogen atꢀ
oms were revealed from the difference electron density synthesis
and refined isotropically. The refinement was performed using
the Chebyshev weighing scheme14 with five parameters: 2.77,
–2.38, 1.08, –1.42, and –0.75. The final R factors were R = 0.047
and RW = 0.047, GOOF = 0.934. The residual electron density
(C=C—C=O); 1580, 1520, 1470, 1430, 1380, 1330. Yield 4b
1.67 g (54%), m.p. 195—197 °C (cf. Ref. 6: 198—199 °C).
Found (%): C, 65.82; H, 3.51; N, 4.79; S, 10.53. C17H11NO3S.
Calculated (%): C, 66.01; H, 3.58; N, 4.53; S, 10.36. The
1H NMR and IR spectra 4b corresponded to those reported
previously.6
Preparation of potassium 4ꢀacetylꢀ2,3ꢀdioxoꢀ1ꢀphenylꢀ2,3ꢀ
dihydroꢀ1Hꢀpyrroleꢀ5ꢀthiolate (5a) and 4ꢀbenzoylꢀ2,3ꢀdioxoꢀ1ꢀ
phenylꢀ2,3ꢀdihydroꢀ1Hꢀpyrroleꢀ5ꢀthiolate (5b). A solution of
oxalyl chloride (1.33 g, 10.5 mmol) in 3 mL of acetone was
added dropwise with stirring at 20 °C over a period of 0.5 h to a
suspension of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamide 1a,b
(10 mmol) and freshly calcined К2CO3 (4.28 g, 31 mmol) in
10 mL of acetone. The reaction mixture was kept for 0.5 h, the
precipitate was filtered off and treated with hot water (2×7 mL),
the aqueous solution was filtered and cooled, and the crystals of
from the difference Fourier series was 0.22 and –0.26 е•Å–3
.
The absorption corrections were applied by azimuthal scanꢀ
ning.15 The full set of Xꢀray diffraction data for compound 3a
is deposited with the Cambridge Structural Database
(CCDC 244043).

Oxalylation of 3ꢀoxoꢀNꢀphenylꢀ3ꢀRꢀpropanethioamides Russ.Chem.Bull., Int.Ed., Vol. 54, No. 3, March, 2005
773
5a,b precipitated. The yield of 5a was 1.71 g (60%), m.p.
294—296 °C. Found (%): C, 50.32; H, 2.57; N, 5.05; S, 11.03.
was filtered and cooled, resulting in crystallization of 5a, yield
1.21 g, 85% (1.05 g, 74%).
C
12H8KNO3S. Calculated (%): C, 50.51; H, 2.83; N, 4.91;
S, 11.24. 1H NMR (DMSOꢀd6), δ: 2.34 (s, Me); 7.16—7.41 (m,
Ph). 13C NMR (DMSOꢀd6), δ: 30.8 (Me); 113.8 (N—C=S);
127.7, 128.2, 129.5, 134.7, 163.1, 175.2, 190.3, 197.7 (MeCO).
IR, ν/cm–1: 3000 (Ph); 1730 (C=O); 1680 (C=O); 1620 (C=O);
1570, 1520, 1460, 1410, 1370. Yield 5b 1.84 g (53%), m.p.
290—293 °C. Found (%): C, 59.02; H, 3.11; N, 3.92; S, 9.01.
References
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C
17H10KNO3S. Calculated (%): C, 58.77; H, 2.90; N, 4.03;
S, 9.23. 1H NMR (DMSOꢀd6), δ: 7.24—7.63 (m, 2 Ph).
13C NMR (DMSOꢀd6), δ: 113.1 (N—C=S); 127.3, 129.0, 129.2,
129.5, 130.6, 135.0, 140.7, 163.4, 173.1, 189.3, 197.3 (Ph—CO).
IR, ν/cm–1: 3100 (Ph); 1740 (C=O); 1670 (C=O); 1610 (C=O);
1510, 1460, 1440.
4ꢀAcetylꢀ5ꢀthioxoꢀ1ꢀphenylpyrrolidineꢀ2,3ꢀdione (6a) and
4ꢀbenzoylꢀ5ꢀthioxoꢀ1ꢀphenylpyrrolidineꢀ2,3ꢀdione (6b). 10% HCl
(2 mL) was added dropwise to a solution of potassium thiolate
5a or 5b (5 mmol) in 8 mL of hot water. The precipitate that
formed was filtered off and dried. The yield of 6a was 1.12 g
(91%), m.p. 180—182 °C. Found (%): C, 58.02; H, 3.46; N, 5.77;
S, 13.04. C12H9NO3S. Calculated (%): C, 58.29; H, 3.67;
N, 5.66; S, 12.97. 1H NMR (CDCl3), δ: 2.72 (s, Me); 7.26—7.52
(m, Ph); 14.62 (s, OH). IR, ν/cm–1: 3100 (Ph); 2600 (SH); 1790
(C=O); 1740 (C=O); 1600 (C=O); 1510, 1460, 1400, 1370. The
yield of 6b was 1.44 g (93%), m.p. 213—215 °C (cf. Ref. 6:
215 °C). Found (%): C, 65.90; H, 3.44; N, 4.78; S, 10.54.
6. W. ZankowskaꢀJasinska and J. Eilmes, Rocz. Chem., 1973,
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7. B. Zaleska, Monatsh. Chem., 1986, 117, 671.
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Betteridge, CRYSTALS, Issue 10, Chemical Crystallography
Laboratory, Univ. of Oxford, 1996.
C
17H11NO3S. Calculated (%): C, 66.01; H, 3.58; N, 4.53;
S, 10.36. The 1H NMR and IR spectra of 6b corresponded to
those reported previously.6 13C NMR (DMSOꢀd6), δ: 114.0
(N—C=S); 127.9, 128.5, 129.3, 132.4, 134.0, 138.2, 164.2, 165.1,
188.4, 198.1 (Ph—CO).
Recyclisation of 4ꢀacetylꢀ5ꢀphenylaminoꢀ2,3ꢀdihydrothioꢀ
pheneꢀ2,3ꢀdione (3a) and 2ꢀacetonylideneꢀ3ꢀphenylꢀ1,3ꢀthiazolꢀ
idineꢀ4,5ꢀdione (4a) to potassium 4ꢀacetylꢀ2,3ꢀdioxoꢀ1ꢀphenylꢀ
2,3ꢀdihydroꢀ1Hꢀpyrroleꢀ5ꢀthiolate (5a). A suspension of thioꢀ
pheneꢀ2,3ꢀdione 3a (or 1,3ꢀthiazolidineꢀ4,5ꢀdione (4a))
(5 mmol) and freshly calcined К2CO3 (1.38 g, 10 mmol) in 6 mL
of acetone was stirred for 3 h at 20 °C. The precipitate was
filtered off and dissolved in 8 mL of hot water, and the solution
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1979, 35, 698.
15. A. C. T. North, D. C. Phillips, and F. S. Mathews, Acta
Crystallogr. (A), 1968, 24, 351.
Received July 26, 2004
in revised form October 15, 2004