REACTION OF CARBON DISULFIDE WITH ACTIVE METHYLENES: NOVEL SYNTHESIS OF THIOPHENE, THIENOTHIOPHENE, THIENOPYRAZOLE AND THIENOPYRIDINE DERIVATIVES

Full text of DOI:10.1135/cccc19951578

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Mohareb, Sherif, Habashi, Abdel-Sayed, Osman:
REACTION OF CARBON DISULFIDE WITH ACTIVE METHYLENES:
NOVEL SYNTHESIS OF THIOPHENE, THIENO[2,3-b]THIOPHENE,
THIENO[3,2-c]PYRAZOLE AND THIENO[3,2-b]PYRIDINE DERIVATIVES
a
a
a
b
Rafat M. MOHAREB , Sherif M. SHERIF , Adiba HABASHI , Nadia I. ABDEL-SAYED
a
and Samia S. OSMAN
a Department of Chemistry,
Faculty of Science, University of Cairo, Giza, Egypt
b Department of Chemistry,
College for Girls, Ain Shams University, Helioplis, Cairo, Egypt
Received February 7, 1995
Accepted June 10, 1995
Thiophenes are important substances for the synthesis of pharmacologically active
compounds and considered as the fundamental key structure units in sulfur containing
heterocycles1–5. Recently our research group studied the reaction of active methylene
reagents with phenyl isothiocyanate followed by cyclization of the resulted adducts
with α-halocarbonyl compounds to give thiophene as well as thiazole derivatives6–8. In
continuation of this synthetic route we report here the reaction of active methylene
compounds with carbon disulfide in basic dimethylformamide solution followed by cycli-
zation of the resulted intermediate adducts with α-halocarbonyl compounds9–12
.
The reaction of the active methylene compounds Ia–If with equimolar amount of
carbon disulfide in dimethylformamide containing potassium hydroxide afforded the
dipotassium disulfide salts IIa–IIf which were not isolated. Subsequent treatment of IIa
with two-fold molar equivalent of phenacyl bromide gave a single product which was
identified as compound III (Scheme 1). It reacted with two-fold molar equivalent of
each of hydrazine hydrate and phenylhydrazine to give the corresponding 1,1′-dihydro-
bispyrazolo[4,3-b]thiophene derivatives IVa and IVb, respectively.
The reaction of IIb with phenacyl bromide gave the thieno[2,3-b]thiophene deriva-
tive V. Compound V reacted with two-fold molar equivalent of each of hydrazine hy-
drate or phenylhydrazine to afford the corresponding dihydrazone derivative VIa, VIb,
respectively. Reaction of disulfide IIc with phenacyl bromide gave the thiophene deri-
vative VII (Scheme 1). All attempts to further cyclize the compound VII under various
reaction conditions failed. The reaction of VII with ethyl cyanoacetate Ib in absolute
ethanol containing a catalytic amount of piperidine gave the thieno[3,2-b]pyridine deri-
vative VIII (Scheme 2). The reaction of VII with malononitrile Ia gave the thieno[3,2-b]-
pyridine derivative IX. Compound VII reacted with acrylonitrile to afford the
thieno[3,2-b]pyridine derivative X. Formation of X was assumed to take place through
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the intermediate formation of the corresponding cyanoethylated derivative13, cycliza-
tion via water elimination and subsequent autooxidation under the reaction conditions14,15
(Scheme 2). The reaction of VII with equimolar amount of each of hydrazine hydrate or
phenylhydrazine gave products XIa and XIb, respectively. Treatment of IId with two-
fold molar equivalent of phenacyl bromide gave the thieno[2,3-b]thiophene derivative
XII (Scheme 1). Compound XII reacted with hydrazine hydrate and with phenylhydra-
zine to give the hydrazone derivatives XIIIa, XIIIb, respectively.
Similarly, the reaction of IIe with phenacyl bromide gave the thiophene derivative
XIV. Compound XIV reacted with two-fold molar equivalent of both of hydrazine hy-
drate or phenylhydrazine to give the thieno[3,2-c]pyrazole derivatives XVa, XVb, re-
spectively. The reaction of XIV with malononitrile Ia, in dioxane containing a catalytic
SCHEME 1
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Mohareb, Sherif, Habashi, Abdel-Sayed, Osman:
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amount of piperidine, yielded the Knoevenagel condensation product XVI. Our attempts
to cyclize XVI under variety of reaction conditions were unsuccessful.
Reaction of IIf with phenacyl bromide gave the thiophene derivative XVII which
reacted with two-fold molar equivalent of each of hydrazine hydrate or phenylhydra-
zine to give the thieno[2,3-c]pyrazole derivatives XVIIIa, XVIIIb.
Subsequent treatment of the intermediate salt IIa with ethyl bromocyanoacetate16
gave the thieno[2,3-b]thiophene derivative XIX which proceeds through the intermedi-
ate formation of the corresponding dithioether followed by hydrolysis, decarboxylation
and intramolecular cyclization17. Similarly, the reaction of IIb with ethyl bromo-
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Mohareb, Sherif, Habashi, Abdel-Sayed, Osman:
cyanoacetate gave the thieno[2,3-b]thiophene derivative XX. The same reaction se-
quence described above for the formation of XIX was proposed.
EXPERIMENTAL
Melting points are uncorrected. IR spectra (KBr) were obtained on a Pye Unicam SP-1000 spectro-
photometer. 1H NMR spectra (δ, ppm) were measured on a Varian EM 390 spectrometer (90 MHz)
in (CD3)2SO as solvent, using TMS as internal standard. Mass spectra were recorded on an AEI MS
30 spectrometer (70 eV). Analytical data were obtained from the Microanalytical Data Unit at Cairo
University.
Thiophene Derivatives III, V, VII, XII, XIV, XVII, XIX and XX (General Procedure)
To a solution of the active methylene compound Ia–If (0.01 mol) in dimethylformamide (20 ml) con-
taining finely ground potassium hydroxide (0.01 mol), carbon disulfide (0.76 g, 0.01 mol) was added.
The reaction mixture was stirred at 25 °C for 24 h and then treated with an appropriate α-haloketone,
phenacyl bromide (4.0 g, 0.02 mol) or ethyl bromocyanoacetate (3.6 g, 0.02 mol). The reaction mix-
ture was stirred for additional 24 h at 25 °C. The solid product formed upon addition of ice/water
containing a few drops of hydrochloric acid (till pH 6) was collected by filtration.
1,6-Diamino-2,5-dibenzoylthieno[2,3-b]thiophene (III). Crystallized from ethanol, m.p. 89 °C,
1
yield 2.5 g (65%). IR spectrum: 3 480–3 430 (NH2); 3 060 (CH aromatic); 1 685, 1 680 (C=O). H NMR
spectrum: 4.48 s, 4.51 s, 4 H (2 × NH2); 7.32–7.49 m, 10 H (2 × C6H5). Mass spectrum, m/z: 378
(M+). For C20H14N2O2S2 (378.5) calculated: 63.47% C, 3.72% H., 7.40% N, 16.94% S; found:
63.02% C, 3.45% H, 7.12% N, 16.80% S.
6-Amino-2,5-dibenzoyl-1-hydroxythieno[2,3-b]thiophene(V). Crystallized from ethanol, m.p. 210 °C,
yield 2.4 g (63%). IR spectrum: 3 630–3 380 (OH, NH2); 3 055 (CH aromatic); 1 690, 1 680 (C=O).
1H NMR spectrum: 4.84 s, 2 H (NH2); 7.32–7.46 m, 10 H (2 × C6H5); 9.93 s, 1 H (OH). Mass
spectrum, m/z: 379 (M+). For C20H13NO3S2 (379.4) calculated: 63.30% C, 3.45% H, 3.69% N,
16.89% S; found: 63.02% C, 3.34% H, 3.52% N, 17.05% S.
3-Amino-2-benzoyl-5-benzoylmethylthio-4-formamidothiophene (VII). Crystallized from dioxane,
m.p. 112 °C, yield 2.7 g (69%). IR spectrum: 3 460–3 370 (NH2); 3 050 (CH aromatic); 1 710, 1 690,
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1
1 680 (C=O). H NMR spectrum: 4.63 s, 2 H (CH2); 5.34 s, 5.62 s, 4 H (2 × NH2); 7.32–7.48 m, 10 H
(2 × C6H5). Mass spectrum, m/z: 296 (M+). For C20H16N2O3S2 (396.5) calculated: 60.58% C, 4.06% H,
7.06% N, 16.17% S; found: 60.34% C, 4.03% H, 7.41% N, 16.05% S.
2,5-Dibenzoyl-1,6-dimethylthieno[2,3-b]thiophene (XII). Crystallized from dioxane, m.p. 125 °C,
1
yield 2.4 g (66%). IR spectrum: 3 060 (CH aromatic); 1 690, 1 685 (C=O); 1 655 (C=C). H NMR
spectrum: 2.22 s, 2.24 s, 6 H (2 × CH3); 7.29–7.42 m, 10 H (2 × C6H5). Mass spectrum, m/z: 376
(M+). For C22H16O2S2 (376.5) calculated: 70.18% C, 4.28% H., 17.03% S; found: 70.02% C, 4.64% H,
17.22% S.
4-Acetyl-2-benzoyl-5-benzoylmethylthio-3-hydroxythiophene (XIV). Crystallized from ethanol, m.p.
186 °C, yield 2.8 g (72%). IR spectrum: 3 550–3 340 (OH); 3 055 (CH aromatic); 2 985 (CH3); 1 700,
1 690, 1 680 (C=O); 1 655 (C=C). 1H NMR spectrum: 2.23 s, 3 H (CH3); 4.52 s, 2 H (CH2); 7.29–7.48 m,
10 H (2 × C6H5); 9.23 s, 1 H (OH). Mass spectrum, m/z: 396 (M+). For C21H16O4S2 (396.3) calcu-
lated: 63.59% C, 4.06% H, 16.18% S; found: 63.20% C, 3.80% H, 16.01% S.
2-Benzoyl-6-benzoylmethylthio-4-ethoxycarbonyl-3-hydroxythiophene (XVII). Crystallized from
ethanol, m.p. 178 °C, yield 3.0 g (71%). IR spectrum: 3 520–3 320 (OH); 3 050 (CH aromatic); 1 710,
1 690–1 675 (C=O); 1 650 (C=C). 1H NMR spectrum: 1.34 t, 3 H, J = 8.0 Hz (CH3); 4.42 s, 2 H
(CH2); 4.54 s, 2 H (CH2); 7.31–7.49 m, 10 H (2 × C6H5); 10.13 s, 1 H (OH). For C22H18O5S2 (426.5)
calculated: 61.95% C, 4.25% H, 15.03% S; found: 61.66% C, 3.79% H, 14.76% S.
1,6-Diamino-2,5-dicyanothieno[2,3-b]thiophene (XIX). Crystallized from ethanol, m.p. 121 °C,
yield 1.5 g (68%). IR spectrum: 3 450–3 380 (NH2); 2 225, 2 220 (CN). 1H NMR spectrum: 4.28 s, 4.39 s,
4 H (2 × NH2). Mass spectrum, m/z: 220 (M+). For C8H4N4S2 (220.3) calculated: 43.62% C, 1.83% H,
25.43% N, 29.11% S; found: 43.28% C, 1.86% H, 25.18% N, 28.69% S.
1-Amino-2,5-dicyano-6-hydroxythieno[2,3-b]thiophene (XX). Crystallized from dimethylformamide,
1
m.p. 197 °C, yield 1.4 g (62%). IR spectrum: 3 650–3 370 (OH, NH2); 2 225, 2 220 (CN). H NMR
spectrum: 4.51 s, 2 H (NH2); 9.35 s, 1 H (OH). Mass spectrum, m/z: 221 (M+). For C8H3N3OS2
(221.2) calculated: 43.42% C, 1.36% H, 18.99% N, 28.98% S; found: 43.48% H, 1.51% H, 18.58% N,
28.68% S.
Thieno[2,3-c]pyrazoles IV, XI, XV, XVIII and the Thieno[2,3-b]thiophenes VI, XIII (General Procedure)
To a solution of III, V, VII, XII, XIV or XVII (0.01 mol) in ethanol (50 ml), hydrazine hydrate (1.0 g,
0.02 mol) or phenylhydrazine (2.2 g, 0.02 mol except of the compound VII, when 0.01 mol was used)
was added. The reaction mixture was heated under reflux for 12 h and then evaporated in vacuo. The
residue was triturated with diethyl ether and the crystals were collected by filtration.
1,1′-Dihydro[5,6:5′,6′]bisthieno[2,3-c]bipyrazole (IVa). Crystallized from dioxane, m.p. 148 °C,
yield 2.8 g (75%). IR spectrum: 3 430–3 380 (NH); 3 050 (CH aromatic); 1 655 (C=C). 1H NMR
spectrum: 7.32–7.52 m, 10 H (2 × C6H5); 8.82 s, 9.21 s, 2 H (2 × NH). For C20H12N4S2 (372.5)
calculated: 64.49% C, 3.24% H, 15.05% N, 17.21% S; found: 64.19% C, 3.02% H, 14.76% N,
17.48% S.
1,1′-Diphenyl[5,6:5′,6′]bisthieno[2,3-c]bipyrazole (IVb). Crystallized from dioxane, m.p. 124 °C, yield
3.3 g (64%). IR spectrum: 3 050 (CH aromatic); 1 655 (C=C). 1H NMR spectrum: 7.30–7.59 m,
20 H (4 × C6H5). For C32H20N4S2 (524.6) calculated: 73.25% C, 3.84% H, 10.67% N, 12.2% S;
found: 72.98% C, 3.86% H, 10.77% N, 12.50% S.
6-Amino-2,5-dibenzoylhydrazono-1-hydroxythieno[2,3-b]thiophene (VIa). Crystallized from di-
methylformamide, m.p. 105 °C, yield 3.6 g (90%). IR spectrum: 3 620–3 380 (OH, NH2); 3 350 (CH
aromatic); 1 655 (C=C). 1H NMR spectrum: 4.82 s, 2 H (NH2); 5.23 s, 5.30 s, 4 H (2 × NH2); 7.32–7.48 m,
10 H (2 × C6H5); 10.13 s, 1 H (OH). For C20H17N5OS2 (407.5) calculated: 58.94% C, 4.20% H,
17.18% N, 15.73% S; found: 58.67% C, 4.08% H, 17.28% N, 16.02% S.
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Mohareb, Sherif, Habashi, Abdel-Sayed, Osman:
6-Amino-2,5-dibenzoylphenylhydrazono-1-hydroxythieno[2,3-b]thiophene (VIb). Crystallized from
dimethylformamide, m.p. 83 °C, yield 4.0 g (72%). IR spectrum: 3 620–3 302 (OH, NH2, NH); 3 060
1
(CH aromatic); 1 655 (C=C). H NMR spectrum: 4.84 s, 2 H (NH2); 7.32–7.59 m, 20 H (4 × C6H5);
8.28 s, 8.32 s, 2 H (2 × NH); 10.21 s, 1 H (OH). For C32H25N5OS2 (559.7) calculated: 68.74% C,
4.50% H, 12.51% N, 11.45% S; found: 69.04% C, 4.24% H, 12.37% N, 11.18% S.
1-Amino-2-benzoyl-(5H)-6-hydroxythieno[2,3-c]pyrazole (XIa). Crystallized from ethanol, m.p.
146 °C, yield 1.9 g (77%). IR spectrum: 3 580–3 320 (OH, NH2, NH); 3 050 (CH aromatic); 1 695
(C=O); 1 650 (C=C). 1H NMR spectrum: 5.36 s, 2 H (NH2); 7.32–7.46, 5 H (C6H5); 8.26 s, 1 H
(NH); 9.81 s, 1 H (OH). For C12H9N3O2S (259.4) calculated: 55.63% C, 3.52% H, 16.54% N,
12.36% S; found: 55.42% C, 3.80% H, 16.46% N, 12.39% S.
1-Amino-2-benzoyl-6-hydroxy-5-phenylthieno[2,3-c]pyrazole (XIb). Crystallized from ethanol,
m.p. 146 °C, yield 2.0 g (77%). IR spectrum: 3 570–3 390 (OH, NH2, NH); 3 060 (CH aromatic); 1 695
1
(C=O); 1 655 (C=C). H NMR spectrum: 5.31 s, 2 H (NH2); 7.32–7.46 m, 5 H (C6H5); 8.26 s, 1 H
(NH); 9.47 s, 1 H (OH). Mass spectrum, m/z: 335 (M+). For C18H13N3O2S (335.4) calculated:
64.46% C, 3.90% H, 12.52% N, 9.55% S; found: 64.24% C, 4.02% H, 12.38% N, 9.71% S.
2,5-Dibenzoylhydrazono-1,6-dimethylthieno[2,3-b]thiophene (XIIIa). Crystallized from ethanol,
m.p. 215 °C, yield 2.8 g (71%). IR spectrum: 3 440–3 380 (NH2); 3 050 (CH aromatic); 1 660
1
(C=C). H NMR spectrum: 2.24 s, 2.26 s, 6 H (2 × CH3); 4.38 s, 4.40 s, 4 H (2 × NH2); 7.32–7.41 m,
10 H (2 × C6H5). Mass spectrum, m/z: 404 (M+). For C22H20N4S2 (404.6) calculated: 65.31% C,
4.98% H, 13.84% N, 15.84% S; found: 64.89% C, 4.68% H, 13.56% N, 15.88% S.
2,5-Dibenzoylphenylhydrazono-1,6-dimethylthieno[2,3-b]thiophene (XIIIb). Crystallized from di-
methylformamide, m.p. 90 °C, yield 3.3 g (90%). IR spectrum: 3 440–3 340 (NH); 3 050 (CH aromatic);
1
2 980 (CH3); 1 660 (C=C). H NMR spectrum: 2.24 s, 6 H (2 × CH3); 7.28–7.52 m, 20 H (4 × C6H5);
8.28 s, 8.35 s, 2 H (2 × NH). For C34H28N4S2 (556.7) calculated: 73.35% C, 5.06% H, 10.06% N,
11.51% S; found: 72.96% C, 4.91% H, 9.87% N, 11.36% S.
6-Acetyl-5-hydrazino-(1H)-3-phenylthieno[3,2-c]pyrazole (XVa). Crystallized from dimethylform-
amide, m.p. 87 °C, yield 1.9 g (70%). IR spectrum: 3 410–3 370 (NH2, NH); 3 050 (CH aromatic);
1
2 975 (CH3); 1 690 (C=O); 1 650 (C=C). H NMR spectrum: 2.25 s, 3 H (CH3); 4.55 s, 2 H (NH2);
7.32–7.49 m, 5 H (C6H5); 9.29 s, 8.52 s, 2 H (2 × NH). Mass spectrum, m/z: 272 (M+). For
C13H12N4OS (272.3): 57.33% C, 4.44% H, 20.57% N, 11.77% S; found: 57.21% C, 4.56% H,
20.57% N, 11.96% S.
6-Acetyl-1,3-diphenyl-5-phenylhydrazinothieno[2,3-c]pyrazole (XVb). Crystallized from dimethyl-
formamide, m.p. 92 °C, yield 3.0 g (72%). IR spectrum: 3 400–3 380 (NH); 3 050 (CH aromatic); 2 975
1
(CH3); 1 690 (C=O); 1 660 (C=C). H NMR: 2.32 s, 3 H (CH3); 7.32–7.59 m, 15 H (3 × C6H5); 8.31 s,
8.51 s, 2 H (2 × NH). For C25H20N4OS (424.5) calculated: 70.73% C, 4.74% H, 13.19% N, 7.55% S;
found: 70.50% C, 4.56% H, 13.37% N, 7.37% S.
2-Benzoylhydrazono-3,4-dihydroxy-(5H)-thieno[2,3-c]pyrazole (XVIIIa). Crystallized from ethanol,
m.p. 117 °C, yield 1.8 g (67%). IR spectrum: 3 570–3 320 (OH, NH2); 3 060 (CH aromatic); 1 660
(C=C). 1H NMR spectrum: 4.22 s, 2 H (NH2); 7.32–7.43 m, 5 H (C6H5); 8.31 s, 1 H (NH); 9.21 s,
9.24 s, 2 H (2 × OH). For C12H10N4O2S (274.3) calculated: 52.54% C, 3.67% H, 20.42% N, 11.68% S;
found: 52.44% C, 3.48% H, 20.22% N, 11.53% S.
2-Benzoylphenylhydrazono-3,4-dihydroxy-5-phenylthieno[2,3-c]pyrazole (XVIIIb). Crystallized
from ethanol, m.p. 188 °C, yield 2.8 g (65%). IR spectrum: 3 590–3 340 (OH, NH); 3 070 (CH
1
aromatic); 1 660 (C=C). H NMR spectrum: 5.22 s, 1 H (NH); 7.32–7.41 m, 15 H (3 × C6H5); 9.32 s,
9.34 s, 2 H (2 × OH). For C24H18N4O2S (426.5) calculated: 67.58% C, 4.25% H, 13.13% N, 7.51% S;
found: 67.37% C, 3.97% H, 13.28% N, 7.27% S.
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6-Benzoylmethylthio-3-cyano-7-formamido-2-hydroxy-4-phenylthieno[3,2-b]pyridine (VIII)
To a solution of VII (3.9 g, 0.01 mol) in absolute ethanol (40 ml) containing piperidine (0.5 ml),
ethyl cyanoacetate (1.1 g, 0.01 mol) was added. The reaction mixture was heated under reflux for 4 h
then evaporated in vacuo. The remaining product was triturated with ether and the formed solid pro-
duct was collected by filtration. Crystallization from dioxane afforded 2.7 g (62%) of compound VIII,
m.p. 180 °C. IR spectrum: 3 590–3 300 (OH, NH2); 3 050 (CH aromatic); 2 890 (CH2); 2 220 (CN);
1 700, 1 680 (C=O); 1 650 (C=C). 1H NMR spectrum: 4.92 s, 2 H (CH2); 5.72 s, 2 H (NH2); 7.32–7.52 m,
10 H (2 × C6H5); 9.82 s, 1 H (OH). For C23H15N3O3S2 (445.5) calculated: 62.00% C, 3.39% H,
9.43% N, 14.39% S; found: 61.77% C, 3.39% H, 9.26% N, 14.54% S.
2-Amino-6-benzoylmethylthio-3-cyano-7-formamido-4-phenylthieno[3,2-b]pyridine (IX)
To a solution of VIII (3.9 g, 0.01 mol) in dioxane (40 ml) containing piperidine (0.5 ml), malononi-
trile Ia (0.66 g, 0.01 mol) was added. The reaction mixture was heated under reflux for 3 h. The
solid product formed upon pouring into ice/water containing few drops of hydrochloric acid was col-
lected by filtration. Crystallization from dioxane afforded 2.9 g (66%), m.p. 108 °C. IR spectrum:
1
3 460–3 350 (NH2); 3 050 (CH aromatic); 2 890 (CH2); 2 220 (CN); 1 690, 1 680 (C=O). H NMR
spectrum: 4.49 s, 2 H (CH2); 4.82 s, 5.28 s, 4 H (2 × NH2); 7.32–7.41 m, 10 H (2 × C6H5). For
C23H16N4O2S2 (444.5) calculated: 62.14% C, 3.62% H, 12.60% N, 14.4% S; found: 62.32% C, 3.33%
H, 12.78% N, 14.03% S.
6-Benzoylmethylthio-3-cyano-7-formamido-4-phenylthieno[3,2-b]pyridine (X)
To a solution of VII (3.9 g, 0.01 mol) in dioxane (30 ml) containing acetic acid (2 ml), acrylonitrile
(0.53 g, 0.01 mol) was added. The reaction mixture was heated under reflux for 10 h, then evapo-
rated in vacuo. The solid product formed upon triturating the remaining product with ether was col-
lected by filtration. Crystallization from dimethylformamide afforded 2.8 g (66%), m.p. 167 °C. IR
spectrum: 3 410–3 750 (NH2); 3 050 (CH aromatic); 2 896 (CH2); 2 220 (CN); 1 690, 1 685 (C=O).
1H NMR spectrum: 4.45 s, 2 H (CH2); 5.28 s, 2 H (NH2); 7.28–7.51 m, 11 H (2 × C6H5, pyridine
H-2). For C23H15N3O2S2 (429.5) calculated: 64.31% C, 3.51% H, 9.78% N, 14.92% S; found:
64.05% C, 3.55% H, 9.87% N, 15.11% S.
2-Benzoyl-5-benzoylmethylthio-3-hydroxy-4-(2′-cyanocrotononitrilo-3′-yl)thiophene (XVI)
To a solution of XIV (3.9 g, 0.01 mol) in dioxane (20 ml) containing piperidine (0.5 ml), malononi-
trile Ia (0.66 g, 0.01 mol) was added. The reaction mixture was heated under reflux for 6 h and the
solid product, so formed upon dilution with ice/water, was collected by filtration. Crystallization
from dioxane afforded 3.4 g (78%) from compound XVI, m.p. 138 °C. IR spectrum: 3 480–3 320
(OH); 3 050 (CH aromatic); 2 985 (CH3); 2 225, 2 220 (CN); 1 685–1 680 (C=O); 1 660 (C=C).
1H NMR spectrum: 2.34 s, 3 H (CH3); 4.41 s, 2 H (CH2); 7.49–7.54 m, 10 H (2 × C6H5); 10.21 s, 1 H
(OH). For C24H16N2O3S2 (444.5) calculated: 64.84% C, 3.62% H, 6.30% N, 14.42% S; found:
64.63% C, 3.50% H, 6.02% N, 14.26% S.
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