Reactions of aroylthioureas with acetylenic esters and dibenzoyl ethylene. Selectivity towards the formation of new 1,3-thiazines

Article abstract of DOI:10.1002/jhet.5570440630

(Chemical Equation Presented) A series of 1,3-thiazines has been synthesized by the reactions of N-aroylsubstituted thioureas with ethyl propiolate, dimethyl but-2-ynedioate and (E)-1,4-diphenyl-but-2-ene-1,4-dione. The reaction of antipyrinylphenyl thiourea with π-deficient acetylenic reagents did not afford the corresponding 1,3-thiazines, whereas pyrrolo-pyrazolopyrimidines were obtained.

Full text of DOI:10.1002/jhet.5570440630

Nov-Dec 2007
1431
Reactions of Aroylthioureas with Acetylenic Esters
and Dibenzoyl Ethylene. Selectivity towards the
formation of New 1,3-Thiazines
Ashraf A Aly,* Essam K. Ahmed and Khalad M. El-Mokadam
Chemistry Department, Faculty of Science, El-Minia University, El-Minia, Egypt.
E-mail: ashraf160@yahoo.com. Tel(Fax): +28623468767
Received February 12, 2007
Ph
N
Ph
O
S
O
N
Ar
O
N
N
Ar
1
R
2
R
+
R
Ar
N
N
+
S
O
H
H
S
O
R1 = H, R2 = CO2Et
R1 = R2 = CO2Me
CO2Me
PhOC
Ph
O
Ph
O
N
N
COPh
N
Me
MeO2C
R
N
N
Me
N
N
Ph
N
Ar
N
N
S
O
O
Ph
O
Ph
H
O
COPh
O
A series of 1,3-thiazines has been synthesized by the reactions of N-aroylsubstituted thioureas with ethyl
propiolate, dimethyl but-2-ynedioate and (E)-1,4-diphenyl-but-2-ene-1,4-dione. The reaction of
antipyrinylphenyl thiourea with ꢀ-deficient acetylenic reagents did not afford the corresponding 1,3-
thiazines, whereas pyrrolo-pyrazolopyrimidines were obtained.
J. Heterocyclic Chem., 44, 1431 (2007).
reacted, in presence of sodium hydroxide, with benzoyl
chloride to provide 1-(3-hydroxyphenyl)-6-oxo-1,6-di-
hydro-2-thiomethyl-pyrimidine-4-carboxylic acid methyl
ester [8]. Additionally, it was known that the reaction of
amidinothioureas, imidoylthioureas, thioacylamidines, O-
methyl-1-aryl-2-thioisobiurets, and 1-aryl-isodithiobiurets
with diethyl azodicarboxylate gave the corresponding
thiadiazoles by the oxidative cyclic S-N bond formation
[9]. A series of 3-alkyl-5-methylene-2-arylimino-1,3-thia-
zolidin-4-ones was obtained from the reaction of N-alkyl-
N'-arylthioureas with dimethyl but-2-ynedioate [10a].
Hyrazinothioureas represented by 1-acylthiosemicarbzides
reacted with phenyl propiolate in acetic acid under reflux
to afford traizolothiazines [10b]. In light of the afore-
mentioned, it appears that the tendency of substituted-
thioureas, as simple molecules, is variable from one
reagent to another. The efficiency of our synthetic
program has been concerned with the use of facile and
elegant methods for the preparation of novel heterocycles
rather than those suffering from low yields due to the
multiple steps described in their preparation [11]. Herein
we report on our findings for the synthesis of various
novel thiazinones, during the reaction of various N-aroyl
thioureas with ethyl propiolate, dimethyl but-2-ynedioate
and (E)-1,4-diphenyl-but-2-ene-1,4-dione. It is note
worthy to mention that 1,3-thiazines have their broad
spectrum as anti-microbial agents [12,13].
INTRODUCTION
Five membered ring systems such as imidazolidin-2-
thiones were obtained from the oxidative cyclization of 1-
dibenzoyl-3-aryl-thioureas with bromine-acetophenone in
the presence of excess triethylamine [1,2]. Manaka [3]
reported on the one-pot condensation of aroylthiourea
with ꢀ-halocarbonyl derivatives to afford 2-acylimino-3-
alkyl-3H-thiazolines. 1,2,4-Triazoles were synthesized by
the direct reaction of N-aryl-N'-benzoylthioureas with
hydrazine hydrate [4]. To the best of our knowledge, six
memberd ring systems were only synthesized as salts
from the reaction of aroylthioureas with SOCl2 in ClCH2-
CH2Cl followed by 70% HCIO4 to give 31-94%
diaminoaryl-oxadiazinium perchlorates, whereas 1,3,5-
thiadiazinium salts were prepared by cyclization of aroyl-
thioureas with POCl3 [5]. Recently, Aly and his group
have demonstrated a very convenient procedure to
synthesize fused thiazoles 3 from the reaction of aroyl-
phenyl thioureas with ꢀ-acceptor quinones (2, 2,3,5,6-
tetrachloro-1,4-benzoquinone, 2,3-dichloro-5,6-dicyano-
1,4-benzoquinone and 2,3-dichloro-1,4-naphthoquinone,
Scheme 1) [6]. However, the reactions of compounds 1
with 2,3-diphenylcyclopropenone (4) in acetic acid
afforded the E and Z mixtures of 3-(3'-aroyl-1-substituted-
thioureido)-2,3-diphenylcinnamic acids (5, Scheme 1) [7].
It was reported that 1-benzoyl-3-(4-hydroxy-phenyl)-urea

1432
A. A Aly, E. K. Ahmed and K. M. El-Mokadam
Vol 44
O
O
Cl
Cl
X
O
X
O
O
O
Ar
N
Ph
Ph
HOOC
S
R
S
O
HN
O
COOH
X
X
N
Ph
Ph
4
N
R
N
H
+
2
HN
S
Ar
Ph
N
R
N
H
Ar
Ph
S
R
Ar
O
E-5
Z-5
1
3
Scheme 1. Reactions of aroylsubstituted thioureas 1 with ꢀ-quinones 2 and 2,3-diphenylcyclopropenone (4)
RESULTS AND DISCUSSION
reaction of 1a-c with 6d can be described as due to
nucleophilic attack of the thiol group to the acetylenic
carbon to form the intermediate 12a-c. Thereafter another
nucleophilic attack from the NH electron lone pair to the
carbonyl in 12a-c accompanied with ethanol elimination
affords the heterocyclic compounds 7a-c (Scheme 3).
Surprisingly, on reacting 1-benzoyl-1'H-pyrazol-4'-yl-
thiourea (1d) with 6d or 6e, the reaction proceeded to
give mainly the corresponding fused pyrolopyrimidines
13 and 14 (Scheme 4). Furthermore, the ir and nmr
spectra of 13 and 14 supported the disappearance of any
thione, thiol, and NH groups or protons. Moreover, the
1H nmr spectra did not show the presence of the methyl
group in position-5 of 1d, whereas the pyrrole-CH
appeared as a singlet at ꢀH 7.96 ppm in case of 13. Mass
spectrum and elemental analysis confirmed the
In the present protocol as exhibited in Scheme 2, the
reaction of N-aroyl-phenyl thioureas 1a-c with ethyl
propiolate (6d) and dimethyl but-2-ynedioate ethyl ester
(6e) under reflux in acetic acid yielded the corresponding
1,3-thizinones 7a-c and 8a-c. Generally, it must be
1
pointed out that the H nmr spectra of 7a-c did not reveal
any proton resonances related to the NH- or –SH groups.
Besides, the 13C nmr spectra did not show any significant
carbon signal related to the presence of the C=S. The
carbon signals related to carbonyl of both the NCOAr and
C-4 absorbed at ꢀC 166.0-167.0 and 170.8-172.0 ppm,
respectively were observed. The ir spectra indicated the
presence of another carbonyl group at ꢁmax 1700-1680
cm-1. The H nmr spectra of 7a-c showed the presence of
1
6- and 5-H protons at ꢀC 6.50-6.60 and 7.00-7.15 ppm,
respectively (see the Experimental Section). The 13C nmr
spectra showed the presence of C-5 and C-6 at ꢀC 118.0-
118.8 and 125.8-126.2 ppm, respectively. Besides, the
azomethine carbon (C-2), in the 13C nmr spectra, absorbed
at ꢀC 156.8-158.0 ppm. The ir spectra of compounds 8a-c
revealed brood absorption bands at ꢁmax 1680-1720 cm-1
corresponding to the carboamide, C-4 and ester groups.
The 1H nmr spectrum for 8a, as an example, revealed only
one singlet at ꢀH 7.10 ppm related to 5-H. The 13C nmr
spectrum showed CH-5 at ꢀC 135.0 ppm, whereas the
methyl-carboxylate and methoxy protons absorbed at ꢀC
52.6 and 50.8 ppm (see the Experimental Section). The
spectral data from nmr, mass and ir as well as the
elemental analyses supported that compounds 7a-c and
8a-c have the structure of 4-substituted-N-(4-oxo-3-
phenyl-3,4-dihydro-[1,3]thiazin-(2Z)-ylidene)-benzamides
and 2-[(Z)-4-substituted-benzoyl-imino]-4-oxo-3-phenyl-
3,4-dihydro-2H-[1,3]thiazine-6-methyl esters. From the
aforementioned we excluded any other suggestions such
as formation of products 9a-c (resulting from the
oxidative process), 10a-c or 11a-c (Scheme 2). The
reaction mechanism depends on the presence of a
tautomerism between the NH and the C=S into the
N=C-SH groups in 1a-c (Scheme 3). It is believed that
attachment by the SH group proceeds faster compared to
the aromatic amine (Scheme 3) [6a,14]. Therefore,
1
molecular formula of 13 as C22H16N4O3. The H nmr
spectrum of 13 revealed two doublets of the pyrimidine
ring at ꢀH 6.00 (5-H, J = 8.0 Hz) and 6.60 ppm (6-H, J =
8.2 Hz). The 13C nmr spectrum of 13 showed the
appearance of several distinctive carbon signals as
shown in Figure 1. On the other hand, mass spectrum
and elemental analysis supported the molecular formula
of 14 as C24H18N4O5. The 1H nmr spectrum of compound
14 revealed two singlets at ꢀH 7.40 and 7.90 ppm, which
were in accord to 6-H and –9, respectively. The 13C nmr
1
spectrum confirmed the H nmr spectral data by the
appearance of CH-6 and –9 at ꢀC 127.4 and 128.4 ppm,
respectively. Additionally, the absorptions of numerous
carbon signals in the 13C nmr spectrum of 14 could be
distinguished as shown in Figure 1. Two methyl groups
resonated as two singlets, in the 1H nmr of 14, at ꢀH 3.36
and 3.98 ppm corresponding to the NCH3 and CH3-ester
protons. The complete spectral data is in good agreement
with the structures of either 13 or 14 (see Figure 1 and
the Experimental Section). The NOE experiments of
compounds 13 and 14 supported their proposed
structures. Hence, irradiation of the 9-H resonance in
either 13 or 14, caused strong enhancement of the ortho-
proton resonances of the benzoyl group (ꢀH 7.70-7.74),
whereas that irradiation slightly affected the N-CH3
protons signal (Figure 1).

Nov-Dec 2007
Reactions of Aroylthioureas with Acetylenic Esters and Dibenzoyl Ethylene
1433
Ph
O
S
Ar
N
AcOH, reflux
10-18 h
1
R
O
N
N
Ar
2
Ph
R
+
Ar
N
H
N
H
+
O
NPh
S
O
S
6d,e
1a-c
a, R1 = H, R2 = CO2Et
b, R1 = R2 = CO2CH3
9a-c
7a-c (80-72%)
Ar
1 and 7-11
Ph
a
b
c
4-OCH3-C6H4-
4-CH3-C6H4-
C6H5-
O
N
N
Ar
Ph
Ph
S
O
O
N
S
O
N
S
CO2CH3
N
N
COAr
COAr
CO2Me
8a-c (85-72%)
10a-c
11a-c
Scheme 2. Reaction of ethyl propiolate (6d) and dimethyl but-2-ynedioate ester (6e) with aroyl-substituted thioureas 1a-c;
synthesis of 1,3-thiazin-4-ones 7a-c and 8a-c.
values of the NMR spectra for compounds 13 and 14
along with their distinguished NOE experiments.
CO2Et
6d
Since, the calculated bond distance [15] between the
carbonyl group and the thiol group is found to be 1.6 Å,
we can suggest a type of hydrogen bond is formed
between them. Consequently, this hydrogen bond can
offer the formation of another seven member ring (Figure
2), which indicates high reactivity of the NH group in 1d
compared with the thiol group.
OEt
..
SH
:
O
S
O
- EtOH
..
NH
7a-c
Ph
Ar
N
N
ArCON
H
Ph
1a-c
12a-c
The reaction mechanism, in case of the formation of 13,
can be simply described by nucleophilic attacking of N3 on
terminal acetylenic-CH to form intermediate 15. Thereafter,
the other nitrogen (N1) undergoes nucleophilic attack on the
carbonyl ester to form the salt 16 (Scheme 5).
Tautomerization of the CH3–C=C-C=O group in 16 to typical
CH2=C-C=C-OH group occurred via proton transfer process
(Scheme 5). Spontaneously, cyclization process is occurred
via nucleophilic addition of the exocylic-CH2 on the thiol
carbon accompanied by elimination of ethanol and hydrogen
sulfide (Scheme 5) to give 17. Ultimately, elimination of the
catalyzed proton affords directly compound 13 (Scheme 5).
Scheme 3. Rationale formation of compounds 7a-c
Furthermore, irradiation of the resonances 5-H (or 6-H) of
13 caused mutual strong saturation with 6-H (or 5-H)
(Figure 1). Besides, NOE experiment where the 5-H (ꢀH
6.60 ppm) signal is saturated in 13 affected moderately
the 9-H (ꢀH 7.96 ppm) signal, whereas irradiation of 6-H
(ꢀH 6.00 ppm) in 14 slightly affected of methyl-ester
protons.
Interestingly, irradiation of the N-CH3 protons in either
13 or 14 slightly caused enhancement to both the ortho-N-
Ph protons and 9-H. Figure 1 shows some distinctive ꢀ'
Ph
O
Ph
O
N
N
Ph
N
O
MeO2C
N
N
CH3
N
CH3
6e
O
S
6d
N
N
CH3
Ph
N
H
1d
N
H
AcOH, reflux
12 h
AcOH, reflux
16 h
N
N
CH3
O
O
Ph
Ph
O
O
13 (85%)
Scheme 4. Reaction of N-benzoyl-antipyrinyl thioureas 1d with ꢀ-dificient acetylenes 6d,e
14 (90%)

1434
A. A Aly, E. K. Ahmed and K. M. El-Mokadam
Vol 44
ꢀ = 140.0
ꢀ = 170.8
ꢀ = 7.20-7.23
ꢀ = 139.8
ꢀ = 7.22-7.26
ꢀ = 170.6
ꢀ = 3.98 (51.0)
ꢀ = 166.0
ꢀ = 3.30 (38.9)
ꢀ = 7.96 (128.0)
ꢀ = 6.00 (108.6)
ꢀ = 132.8
O
O
NOE
N
ꢀ = 3.36 (39.4)
ꢀ = 124.0
NOE
CH3
N
3
ꢀ = 132.0
N
CO2Me
CH3
3
N
N
NOE
N
ꢀ = 127.0
9
NOE
NOE
7
7
N
ꢀ = 126.6
NOE
N
O
ꢀ = 142.0
ꢀ = 7.90 (128.4)
O
O
ꢀ = 6.60 (135.4)
ꢀ = 162.6
ꢀ = 7.70-7.74
O
ꢀ = 162.0
ꢀ = 7.98
ꢀ = 7.40 (127.4)
ꢀ = 130.4
ꢀ = 130.6
ꢀ = 127.4
ꢀ = 164.0
ꢀ = 163.8
13
14
Figure 1. Distinctive ꢀ's values and NOE experiments of compounds 13 and 14
during its reaction with (E)-18 and N-[(R)-6-benzoyl-3-
(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-
yl]-4-phenyl-3,6-dihydro-[1,3]-thiazin-(2Z)-ylidene]-4-
methyl-benzamide (19d) was obtained (Scheme 6). The
difference in reactivity during the reaction of 1d with
either 6d and/or 18 might be attributed to the steric effect.
In other meaning, the combination between 1d and 18
might constitute a type of steric that enables the thiol
group to react more easily compared with NH group. The
spectral data along with the elemental analysis excluded
the suggested formation of other products such as 20a-d
(Scheme 6). The reaction mechanism can be simply
outlined as shown in Scheme 6. In conclusion, we have
Ph
N
Ph
N
H
O
O
N
N
SH
S
Me
Me
1d
R
N
N
R
Me
Me
Figure 2. Hydrogen bond formed between
the thiol and carbonyl groups in 1d
In order to explore the above mode of synthesis for
another class of heterocycles, under similar reaction
conditions, the reaction of (E)-1,4-diphenyl-but-2-ene-
1,4-dione (E-18) with thioureas 1a-d successfully
proceeded to afford the corresponding 1,3-thiazines 19a-d
1
thus demonstrated
a very convenient procedure to
(Scheme 6). The H nmr spectrum of 19a, as an example,
synthesize of 1,3-thiazines by the reaction of but-2-
ynedioic acid, propynoic acid ethyl ester, and (E)-1,4-
revealed the presence of OCH3, C-6 (thiazine), C-5
(thiazine) and N-Ph 2 CH2 at ꢀH 3.94, 4.80 ppm (1 H, d, J
= 11.5 Hz), 6.30 (1 H, d, J = 11.4 Hz) and 6.70 (dd, J =
8.0, 1.2 Hz) ppm. The 13C nmr spectrum supported the 1H
nmr spectroscopic data by the distinctive appearance of
the carbon signals represented the thiazine skeleton and
its environments at ꢀC 44.4 (CH-6), 54.0 (OCH3), 100.0
(CH-5), 115.0 (N-Ph 2 CH2'), 116.2 (Ph 2 CH2'), 142.6
(C-4), 144.2 (N-PhC), 160.8 (CH3OArC), 162.8 (C=N, C-
diphenyl-but-2-ene-1,4-dione
with
aroyl-substituted
thioureas under reflux in acetic acid.
EXPERIMENTAL
General Consideration. All mps were recorded on a
1
Gallenkamp apparatus. H NMR and 13C NMR spectra
1
2), 168.0 (N-C=O) and 180.0 ppm (COPh). The H nmr
1
(Bruker AM 400, H: 400.13 MHz, 13C: 100.6 MHz); s =
spectrum of 19a apparently supported the (R)-configura-
tion due to the presence of H-6 in trans-form (J = 11.5
Hz) in relation to H-5 (J = 11.4 Hz). In the case of 19d,
the 13C nmr spectrum revealed several distinctive carbon
signals such as at ꢀC 15.7, 35.8, 45.2, 93.0, 106.0, 130.0,
130.4, 142.0, 143.4, 160.0, 162.0, 166.6, and 179.2 ppm
corresponding to CH3-pyrazole, pyrazole N CH3, CH 6,
CH 5, pyrazole C-4, pyrazole C-3, thiazine C-3, thiazine
C-4, N-Ph C, pyrazole-CO, thiazine C-2, N-C=O and
C=O, respectively (see the Experimental Section).
Compound 1d did not show any abnormal reactivity
singlet, d = doublet, dd = double-doublet and m =
multiplet. The NMR samples were dissolved in dimethyl
sulfoxide-d6 solutions. Coupling constants were expressed
in Hz. Elemental analyses were carried at the Assuit
Microanalysis Center of Assiut University. Mass
spectroscopy was performed with a Finnigan MAT 8430
spectrometer at 70 eV, Institute of Organic Chemistry,
Technical University-Braunschweig, Germany. IR spectra
were run on a Shimadzu 470 spectrometer using
potassium bromide pellets.

Nov-Dec 2007
Reactions of Aroylthioureas with Acetylenic Esters and Dibenzoyl Ethylene
1435
Ph
O
O
Ph
O
N
N
N
CH3
OEt
Ph
N
N
6d
N
CH3
N
O
CH3
+
O
EtO
N
SH
H2C
O
SH
..
H
-O
N
SH
O
N
O
CH3
OEt
16
Ph
N
N
Ph
H
Ph
Ph
H
15
CH3
1d
O
Ph
HO
N
N
N
N
CH3
CH3
N
+
N
+
H2O + H
- H
+
N
OEt
+
CH2
13
N
-O
SH
O
O
- (H2S + EtOH)
O
Ph
Ph
17
Scheme 5. Mechaistic pathway of the reaction of 1d and acetylenic carboxylate 6d
PhOC
Ph
Ph
N
HO
Ph
Ph
:
HN
N
N
Ar
Ar
(E)-18
COPh
O
..
S
O
S
O
H
:
O
SH
H
COPh
COPh
Ph
Ar
N
N
22a-d
21a-d
H
- H2O
Ph
Ph
N
Ph
N
N
Ar
Ph
S
AcOH
24-48 h
PhOC
1a-d
+
S
O
N
COAr
COPh
H
H
COPh
COPh
(E)-18
1, 19 and 20
Ar
20a-d
19a-d (80-90%)
4-OCH3-C6H4-
4-CH3-C6H4-
C6H5-
a
b
c
d
antipyrinyl-
Scheme 6. Reactions of aroyl-substituted thioureas 1a-d with E-1,4-diphenyl- but-2-ene-1,4-dione (E-18);
synthesis of 1,3-thiazines 19a-d.
Starting materials. Aroylthioureas 1a-c and 1d were
dissolving in dry acetone (30-50 mL) and subjected to
preparative plates chromatography (silica gel), toluene: ethyl
acetate (10:1). In the case of reaction of 1a-d with (E)-18, the
formed solid products 19a-d were collected by filtration and the
precipitates were washed with water and ethanol until the odor
of acetic acid disappeared. The obtained products were
recrystallized from the stated solvents.
41-Methoxy-N-[4-oxo-3-phenyl-3,4-dihydro-[1,3]-thiazin-
(2Z)-ylidene]-benzamide (7a) was obtained as yellow crystals
(0.54 g, 80%), mp 260 °C (ethanol); 1H nmr (dimethyl
sulfoxide-d6): ꢀ 3.90 (3 H, s, OCH3), 6.60 (1 H, d, J = 7.0 Hz, 6-
prepared according to literatures [14] and [7], respectively.
Reaction of 1a-d with 6d,e and (E)-18, General procedure.
Into a 250 cm3 two-necked round bottom flask containing a
solution of 1a-d (2 mmol) in glacial acetic acid (50-80 mL), a
solution of 2 mmol of either 6d,e (or E-18) in glacial acetic (20
mL) was dropwisely added with stirring. The mixture was
stirred at room temperature for 1 h and then gently refluxed with
stirring (the reaction was monitored by TLC analyses). In the
case of products 7a-d and 8a-d, the solvent was evaporated
under vacuum and the formed solid products were purified by

1436
A. A Aly, E. K. Ahmed and K. M. El-Mokadam
Vol 44
H), 6.92 (2 H, dd, J= 8.0, 1.4 Hz, Ar H), 7.10 (1 H, d, J = 7.2
Hz, 5-H), 7.34-7.42 (4 H, m, Ar H), 7.75-7.90 (3 H, m, Ar H)
ppm; 13C nmr (dimethyl sulfoxide-d6): ꢀ 53.0 (OCH3), 118.8
(CH-6), 126.2 (CH-5), 126.8 (Ph CH, CH4/), 127.0, 127.6,
128.0, 130.0 (Ar 2 CH), 133.8 (Ar C-CO), 138.9 (N-Ar C),
150.0 (H3COAr C), 158.0 (C-2), 167.0 (= NCOAr), 172.0 (C-4)
ppm; ir (potassium bromide): 3060-2980 (Ar CH, w), 2930-2860
(aliph. CH, m), 1700-1680 (C=O, s), 1600 (C=N, s), 1496 (C=C,
m), 1450 (s), 920 (m) cm-1; uv (CH3CN); ꢁmax nm (log ꢂ) 420
(3.90 ); ms (electron impact, 70 eV): m/z (%) 339 ([M+1], 24%),
338 ([M+], 100), 323 (14), 307 (28), 230 (40), 202 (54), 152
(26), 136 (82), 86 (24), 77 (40). Anal. Calcd. for C18H14N2O3S
(338.39): C, 63.89; H, 4.17; N, 8.28; S, 9.48. Found: C, 63.75;
H, 4.10; N, 8.20; S, 9.40.
107 (16), 92 (10), 77 (26), 64 (14). Anal. Calcd. for C20H16N2O5S
(396.42): C, 60.60; H, 4.07; N, 7.07; S, 8.09. Found: C, 60.75;
H, 4.00; N, 7.00; S, 8.02.
2-[(Z)-4-Methyl-benzoylimino]-4-oxo-3-phenyl-3,4-dihydro]-
2H-[1,3]thiazine-6-carboxylic acid methyl ester (8b) was
obtained as yellow crystals (0.61 g, 80%), mp 198 °C
(methanol); 1H nmr (dimethyl sulfoxide-d6): ꢀ 2.34 (3 H, s,
CH3), 3.94 (3 H, s, ester OCH3), 7.06 (1 H, s, J = 7.2 Hz, 5-H),
6.95-7.30 (7 H, m, Ar H), 7.60 (2 H, dd, J = 8.2, 1.2 Hz, Ar H)
ppm; 13C nmr (dimethyl sulfoxide-d6): ꢀ 32.8 (CH3), 50.4 (ester
OCH3), 125.5 (Ph CH, CH-4/), 126.8, 127.2, 127.6, 128.2 (Ar
2CH), 130.4 (Ar C-CO), 135.4 (CH-5), 137.8 (H3C-Ar C), 138.0
(N-Ar C), 155.2 (C-6), 158.2 (C-2), 165.5 (C=O-ester), 167.6
(=NCOAr), 173.4 (C-4) ppm; ir (potassium bromide): 3084-
3005 (Ar CH, m), 2980-2890 (aliph. CH, m), 1716-1684 (C=O,
br, s), 1608 (C=N, s), 1520 (C=C, s), 1460 (s), 918 (s) cm-1; uv
(CH3CN) ꢁmax nm (log ꢂ) 3.7 (3.50); ms (electron impact, 70
eV): m/z (%) 380 ([M+], 100), 365 (20), 288 (60), 260 (54), 135
(64), 120 (24), 112 (34), 77 (40). Anal. Calcd. for C20H16N2O4S
(380.43): C, 63.15; H, 4.24; N, 7.36; S, 8.43. Found: C, 63.05;
H, 4.20; N, 7.34; S, 8.42.
4'-Methyl-N-[4-oxo-3-phenyl-3,4-dihydro-[1,3]-thiazin-(2Z)-
ylidene]-benzamide (7b) was obtained as yellow crystals (0.48
1
g, 75%), mp 298°C (ethanol); H nmr (dimethyl sulfoxide-d6): ꢀ
2.34 (3 H, s, CH3), 6.58 (1 H, d, J = 7.2 Hz, 6-H), 7.15 (1 H, d, J
= 7.0 Hz, 5-H), 7.28-7.36 (4 H, m, Ar H), 7.60-7.80 (5 H, m, Ar
H) ppm; 13C nmr (dimethyl sulfoxide-d6): ꢀ 32.8 (CH3), 118.4
(CH-6), 126.2 (CH-5), 126.6 (Ph-CH, CH-4/), 127.0, 127.4,
127.8, 129.6 (Ar 2CH), 133.6 (Ar C-CO), 134.6 (CH3Ar C),
138.2 (N-ArC), 157.2 (C-2), 166.6 (=NCOAr), 171.2 (C-4) ppm;
ir (potassium bromide): 3050-2986 (Ar CH, w), 2930-2860
(aliph. CH, m), 1700-1685 (C=O, s), 1596 (C=N, s), 1494 (C=C,
m), 1450 (s), 918 (m) cm-1; uv (CH3CN) ꢁmax nm (log ꢂ) 418
(3.80); ms (electron impact, 70 eV): m/z (%) 322 ([M+], 100),
306 (30), 230 (34), 202 (50), 188 (12), 152 (26), 144 (20), 136
(82), 120 (24), 86 (24), 77 (30). Anal. Calcd. for C18H14N2O2S
(322.39): C, 67.06; H, 4.38; N, 8.69; S, 9.95. Found: C, 67.12;
H, 4.34; N, 8.62; S, 9.90.
2-[(Z)-Benzoylimino]-4-oxo-3-phenyl-3,4-dihydro-2H-[1,3]-
thiazine-6-carboxylic acid methyl ester (8c) was obtained as
1
yellow crystals (0.52 g, 72%), mp 210 °C (methanol); H nmr
(dimethyl sulfoxide-d6): ꢀ 3.94 (3 H, s, ester OCH3), 6.95 (1 H, s,
J = 7.0 Hz, 5-H), 6.94-7.20 (6 H, m, Ph H), 7.40-7.50 (2 H, m, Ph
H), 7.66 (2 H, dd, J = 8.0, 1.2 Hz, Ph H) ppm; 13C NMR
(dimethyl sulfoxide-d6): ꢀ 50.2 (ester-OCH3), 125.0, 125.8 (Ph
CH, CH4/), 126.8, 127.6, 128.0, 128.2 (Ph 2 CH), 130.0 (Ph C-
CO), 134.2 (CH-5), 138.6 (N-Ph C), 155.0 (C-6), 158.0 (C-2),
165.8 (C=O-ester), 167.0 (=NCOPh), 172.6 (C-4) ppm; ir
(potassium bromide): 3070-3008 (Ph CH, m), 1718-1680 (C=O,
br, s), 1610 (C=N, m), 1560 (C=C, m), 1450 (m), 916 (s) cm-1; uv
(CH3CN) ꢁmax nm (log ꢂ) 3.6 (3.40); ms (electron impact, 70 eV):
m/z (%) 366 ([M+], 100), 288 (54), 260 (64), 126 (22), 112 (32),
77 (50). Anal. Calcd. for C19H14N2O4S (366.40): C, 62.29; H,
3.85; N, 7.65; S, 8.75. Found: C, 65.15; H, 3.80; N, 7.64; S, 8.70.
8-Benzoyl-1-methyl-2-phenyl-1H-pyrazolo-[3',4':4,5]pyrrolo-
[1,2-a]-pyrimidine-3,7-(2H,8H)-dione (13) was obtained as
pale brown crystals (0.70 g, 85%), mp 242 °C (ethanol); 1H nmr
(dimethyl sulfoxide-d6): ꢀ 3.30 (3 H, s, NCH3), 6.00 (1 H, d, J =
8.0 Hz, 5-H), 6.60 (1 H, d, J = 8.2 Hz, 6-H), 7.00-7.30 (6 H, m,
Ph H), 7.60-7.70 (2 H, m), 7.96 (1 H, s, pyrrole-H-9), 7.98 (2 H,
dd, J = 8.0, 1.4 Hz, CO-Ph CH2'). 7.96 (1 H, s, pyrrole-H-9)
ppm; 13C nmr (dimethyl sulfoxide-d6): ꢀ 38.9 (NCH3), 108.6
(CH-5), 126.6 (C-9a), 126.8, 127.2 (Ph CH, CH-4/), 127.4 (C-
8a), 128.0 (CH-9), 128.4, 128.6, 128.8, 129.0 (Ph 2CH), 130.6
(Ph-C CO), 132.8 (C-3a), 135.4 (CH-6), 140.0 (N-Ph C), 162.6
(C-7), 163.8 (benzoyl-CO), 170.8 (C-3) ppm; ir (potassium
bromide): 3060-2990 (Ar CH, m), 2960-2840 (aliph. CH, m),
1710 (CO, s), 1680 (C=O, s), 1600 (C=N, m), 1498 (C=C, m),
1450 (m), 922 (m) cm-1; uv (CH3CN) ꢁmax nm (log ꢂ) 390 (3.82).
MS (electron impact, 70 eV): m/z (%) 384 ([M+], 100), 368 (20),
306 (34), 292 (36), 278 (40), 196 (18), 170 (26), 105 (64), 91
(38), 56 (60). Anal. Calcd. for C22H16N4O3 (384.40): C, 68.74; H,
4.20; N, 14.58. Found: C, 68.69, H, 4.30; N, 14.50.
N-[4-Oxo-3-phenyl-3,4-dihydro-[1,3]-thiazin-(2Z)-ylidene]-
benzamide (7c) was obtained as pale yellow crystals (0.44 g,
72%), mp 238 °C (ethyl acetate/benzene); 1H nmr (dimethyl
sulfoxide-d6): ꢀ 6.50 (1 H, d, J = 7.0 Hz, 6-H), 7.00 (1 H, d, J =
7.0 Hz, 5-H), 7.10-7.26 (5 H, m, Ph H), 7.54-7.76 (5 H, m, Ph
H) ppm; 13C nmr (dimethyl sulfoxide-d6): ꢀ 118.0 (CH-6), 125.8
(CH-5), 126.0, 126.8 (Ph-CH, CH-4/), 128.2, 128.6, 128.8, 129.2
(Ph 2CH), 133.8 (Ar C-CO), 138.0 (N-Ph C), 156.8 (C-2), 166.0
(= NCOPh), 170.8 (C-4) ppm; ir (potassium bromide): 3040-
2980 (Ph CH, w), 1700-1682 (C=O, s), 1600 (C=N, s), 1496
(C=C, m), 1450 (s), 918 (s) cm-1; uv (CH3CN) ꢁmax nm (log ꢂ)
410 (3.60); ms (electron impact, 70 eV): m/z (%) 308 ([M+],
100), 230 (26), 202 (48), 188 (16), 150 (24), 142 (20), 136 (32),
105 (60), 86 (20), 77 (26). Anal. Calcd. for C17H12N2O2S
(308.36): C, 66.22; H, 3.92; N, 9.08; S, 10.40. Found: C, 66.12;
H, 3.89; N, 9.00; S, 10.30.
2-[(Z)-4-Methoxy-benzoylimino]-4-oxo-3-phenyl-3,4-
dihydro]-2H-[1,3]thiazine-6-carboxylic acid methyl ester (8a)
was obtained as yellow crystals (0.67 g, 85%), mp 212 °C
1
(ethanol); H nmr (dimethyl sulfoxide-d6): ꢀ 3.90 (3 H, s, ester
OCH3), 3.96 (3 H, s, OCH3), 6.85 (1 H, s, J = 7.0 Hz, 5-H), 7.35-
7.42 (2 H, m, Ar H), 7.48-7.60 (5 H, m, Ar-H), 7.96-7.98 (2 H,
dd, J = 8.0, 1.2 Hz, Ar H) ppm; 13C nmr (dimethyl sulfoxide-d6):
ꢀ 50.8 (OCH3), 52.6 (ester OCH3), 125.8 (Ph CH, CH-4/), 128.9,
130.5, 131.8.8, 132.8 (Ar 2CH), 132.8 (Ar C-CO), 133.8 (CH-
5), 136.4 (N-Ar C), 152.0 (CH3OAr C), 155.0 (C-6), 158.4 (C-
2), 165.4 (C=O-ester), 167.8 (=NCOAr), 171.4 (C-4) ppm; ir
(potassium bromide): 3080-2990 (Ar CH, m), 2960-2870 (aliph.
CH, m), 1720-1680 (C=O, br, s), 1610 (C=N, s), 1500 (C=C, s),
1460 (m), 920 (s) cm-1; uv (CH3CN) ꢁmax nm (log ꢂ) 3.9 (3.60);
ms (electron impact, 70 eV): m/z (%) 396 ([M+], 100), 135 (64),
Methyl 8-benzoyl-1-methyl-3,7-dioxo-1-phenyl-2,3,7,8-tetra-
hydro-1H-pyrazolo-[3',4':4,5]pyrrolo-[1,2-a]-pyrimidine-
5-carboxylate (14) was obtained as pale brown crystals (0.83 g,
1
90%), mp 202 °C (methanol); H nmr (dimethyl sulfoxide-d6): ꢀ
3.36 (3 H, s, NCH3), 3.98 (3 H, s, CH3-ester), 7.10-7.30 (6 H, m,
Ph H), 7.40 (1 H, s, 6-H), 7.60-7.64 (2 H, m), 7.70-7.74 (2 H, m,

Nov-Dec 2007
Reactions of Aroylthioureas with Acetylenic Esters and Dibenzoyl Ethylene
1437
CO-Ph CH2'), 7.90 (1 H, s, 9-H) ppm; 13C nmr (dimethyl
sulfoxide-d6): ꢀ 39.4 (NCH3), 51.0 (CH3-ester), 124.0 (C-9a),
127.0 (C-8a), 127.4 (CH-6), 127.6, 127.8 (Ph-CH, CH-4/), 128.4
(CH-9), 128.0, 128.4, 128.6, 128.8 (2 Ph CH), 130.6 (Ph C-CO),
132.0 (C-3a), 139.8 (N-Ph C), 142.0 (C-5), 162.0 (C-7), 164.0
(benzoyl-CO), 166.0 (CO ester), 170.6 (C-3) ppm; ir (potassium
bromide): 3060-2990 (Ar CH, m), 2960-2840 (aliph. CH, m),
1716 (CO, s), 168.0 (C=O, s), 1600 (C=N, m), 1498 (C=C, m),
1450 (m), 922 (m) cm-1; uv (CH3CN) ꢁmax nm (log ꢂ) 430
(4.24); ms (electron impact, 70 eV): m/z (%) 442 ([M+], 100),
410 (18), 365 (40), 366 (60), 245 (38), 228 (66), 186 (44), 119
(44), 105 (82), 91 (38), 77 (62), 56 (46). Anal. Calcd. for
C24H18N4O5 (442.43): C, 65.15; H, 4.10; N, 12.66. Found: C,
65.30, H, 4.10; N, 12.60.
N-[(R)-6-Benzoyl-3,4-diphenyl-3,6-dihydro-[1,3]thiazin-(2Z)-
ylidene]-4'-methoxy-benzamide (19a) was obtained as pale
brown crystals (0.91 g, 90%), mp 312 °C (ethanol); 1H nmr
(dimethyl sulfoxide-d6): ꢀ 3.94 (3 H, s, OCH3), 4.80 (1 H, d, J =
11.5 Hz, H-6), 6.30 (1 H, d, J = 11.4 Hz, H-5), 6.70 (2 H, dd, J =
8.0, 1.2 Hz), 6.90 (2 H, dd, J = 8.2, 1.4 Hz), 7.00-7.20 (5 H, m),
7.30-7.35 (1 H, m), 7.45-7.64 (7 H, m), 7.80 (2 H, dd, J = 8.2,
1.4 Hz) ppm; 13C nmr (dimethyl sulfoxide-d6): ꢀ 44.4 (CH-6),
54.0 (OCH3), 100.0 (CH-5), 115.0 (N-Ph 2 CH2'), 116.2
(CH3OPh 2CH2'), 118.8 (N-Ph CH4'), 126.0, 126.6 (Ph CH
CH4'), 127.4, 128.0, 128.2, 128.6, 129.4 (Ph 2CH), 132.0, 134.6
(Ph C), 135.6 (CH3OPh-2 CH3'), 136.8 (Ph C-CO), 142.6 (C-4),
144.2 (N-Ph C), 160.8 (CH3O-Ph C), 162.8 (C=N, C-2), 168.0
(N-C=O), 180.0 (COPh) ppm; ir (potassium bromide): 3072-
2980 (Ar CH, m), 2970-2880 (aliph. CH, m), 1700-1690 (C=O,
s), 1598 (C=N, m), 1496 (C=C, m), 1452 (m), 920 (m) cm-1; uv
(CH3CN) nm ꢁmax nm (log ꢂ) 420 (3.83); ms (electron impact,
70 eV): m/z (%) 504 ([M+], 30), 398 (12), 324 (10), 310 (12),
105 (100), 99 (24), 57 (16). Anal. Calcd. for C31H24N2O3S
(504.61): C 73.79, H 4.79, N 5.55, S 6.35. Found C, 73.86; H,
4.80; N, 5.50; S, 6.35.
CO), 142.0 (C-4), 143.4 (N-Ph C), 162.0 (C=N, C-2), 166.6 (N-
C=O), 179.2 (COPh) ppm; ir (potassium bromide): 3080-2996
(Ar CH, m), 1696-1690 (C=O, s), 1600 (C=N, s), 1500 (C=C,
w), 918 (s) cm-1; uv (CH3CN) ꢁmax (log ꢂ) 410 (3.4); ms
(electron impact, 70 eV): m/z (%) 474 ([M+], 32), 396 (38), 368
(34), 264 (34), 186 (20), 105 (100), 91 (24), 77 (60). Anal.
Calcd. for C30H22N2O2S (474.59): C, 75.93; H, 4.67; N, 5.90; S,
6.76. Found C, 76.10; H, 4.70; N, 5.82; S, 6.72.
N-[(R)-6-Benzoyl-3-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-
1H-pyrazol-4-yl]-4-phenyl-3,6-dihydro-[1,3]thiazin-(2Z)-
ylidene]-4-methyl-benzamide (19d) was obtained as pale
brown crystals (1.0 g, 87%), mp 342 °C (acetone); 1H nmr
(dimethyl sulfoxide-d6): ꢀ 1.68 (3 H, s, pyrazole CH3), 2.50 (3
H, s, N-pyrazole CH3), 4.68 (1 H, d, J= 13.8 Hz), 5.40 (1 H, d, J
= 13.9 Hz), 6.70 (2 H, dd, J = 8.0, 1.2 Hz, N-pyrazole-Ph 2CH
2'), 6.95-7.60 (10 H, m), 7.80-7.98 (8 H, m) ppm; 13C nmr
(dimethyl sulfoxide-d6): ꢀ 15.7 (CH3 pyrazole), 35.8 (CH3-N
pyrazole), 45.2 (CH-6), 93.0 (CH-5), 106.0 (pyrazole C-4),
114.2 (N pyrazole Ph 2CH2'), 118.0 (N pyrazole-PhCH 4'),
126.8, 127.0, 127.2 (PhCH 4'), 127.6, 128.0, 128.4, 128.6,
129.0, 129.6, 130.2 (Ph 2 CH), 130.8 (pyrazole C-3), 132.4,
132.8 (Ph C), 136.3 (Ph C-CO), 142.0 (C-4), 143.4 (N-Ph C),
160.0 (pyrazole CO), 162.0 (C=N, C-2), 166.6 (N-C=O), 179.2
(COPh) ppm; ir (potassium bromide): 3080-2994 (Ar CH, m),
2990-2894 (aliph. CH, m), 1706-1692 (C=O, s), 1600 (C=N, s),
1500 (C=C, s), 918 (s) cm-1; uv (CH3CN) ꢁmax nm (log ꢂ) 435
(3.81); ms (electron impact, 70 eV): m/z (%) 584 ([M+], 40), 568
(14), 554 (16), 506 (18), 478 (42), 402 (24), 396 (30), 296 (30),
186 (20), 105 (100), 91 (24), 77 (54). Anal. Calcd. for
C35H28N4O3S (584.70): C, 71.90; H, 4.83; N, 9.58; S, 5.48.
Found C, 72.10; H, 4.80; N, 9.50; S, 5.40.
REFERENCES
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N-(R)-6-Benzoyl-3,4-diphenyl-3,6-dihydro-[1,3]thiazin-(2Z)-
ylidene)-4'-methyl-benzamide (19b) was obtained as pale
brown crystals (0.83 g, 85%), mp 330 °C (ethyl acetate); 1H NMR
(dimethyl sulfoxide-d6): ꢀ 3.38 (3 H, s, CH3), 4.72 (1 H, d, J 13.7
Hz), 5.45 (1 H, d, J = 13.8 Hz), 6.60 (2 H, dd, J = 8.2, 1.2 Hz),
6.95-7.25 (8 H, m), 7.30-7.70 (9 H, m) ppm; 13C NMR (dimethyl
sulfoxide-d6): ꢀ 32.8 (CH3), 44.0 (CH-6), 92.6 (CH-5), 114.8 (N-
Ph 2 CH2'), 118.4 (N-Ph CH4'), 126.0, 126.6 (Ph CH CH4'),
127.2, 127.6, 128.0, 128.2, 128.4, 128.6, 128.8 (Ph 2CH), 132.2,
132.6 (Ph C), 134.8 (CH3CPh C), 136.6 (Ph C-CO), 142.4 (C-4),
143.8 (N-Ph C), 162.2 (C=N, C-2), 166.8 (N-C=O), 179.5 (COPh)
ppm; ir (potassium bromide): 3060-2990 (Ar CH, m), 2980-2886
(aliph. CH, m), 1700-1692 (C=O, s), 1595 (C=N, s), 1496 (C=C,
m), 920 (m) cm-1; uv (CH3CN) ꢁmax nm (log ꢂ) 416 (3.6); ms
(electron impact, 70 eV): m/z (%) 488 ([M+], 28), 472 (20), 396
(40), 368 (24), 324 (20), 312 (24), 172 (24), 108 (38), 91 (30), 77
(100). Anal. Calcd. for C31H24N2O2S (488.61): C, 76.20; H, 4.95;
N, 5.73; S, 6.56. Found C, 76.00; H, 4.90; N, 5.70; S, 6.50.
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[6] a) Aly, A. A.; Ahmed, E. K.; El-Mokadam, K. M. J. Sulf.
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Danilkina, N. A.; Mikhailov, L. E.; Ivin, B. A. In the 3rd Euro-Asian
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[11] a) Aly, A. A. Org. Biomol. Chem. 2003, 1, 756; b) Aly, A. A.
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N-[(R)-6-Benzoyl-3,4-diphenyl-3,6-dihydro-[1,3]thiazin-(2Z)-
ylidene]-benzamide (19c) was obtained as pale brown crystals
(0.74 g, 80%), mp 320 °C (acetone). 1H nmr (dimethyl
sulfoxide-d6): ꢀ 4.70 (1 H, d, J = 13.8 Hz), 5.50 (1 H, d, J = 13.8
Hz), 6.62 (2 H, dd, J = 8.2, 1.2 Hz), 6.95-7.25 (8 H, m), 7.30-
7.70 (9 H, m) ppm; 13C nmr (dimethyl sulfoxide-d6): ꢀ 44.2 (CH-
6), 92.2 (CH-5), 115.2 (N-Ph 2 CH2'), 118.0 (N-Ph CH4'),
125.8, 126.2, 126.8 (Ph CH 4'), 127.4, 128.2, 128.6, 129.0,
129.6, 130.2, 131.0 (Ph 2CH), 132.4, 132.8 (Ph C), 136.3 (Ph C-

1438
A. A Aly, E. K. Ahmed and K. M. El-Mokadam
Vol 44
Tetrahedron 2006, 62, 4498.
[14] Brindley, J. C.; Caldwell, J. M.; Meakins, G. D.; Plackett, S.
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