4-(2-Aminophenyl)-1,2,3-thia- and -selenadiazoles as a Source of 2-Indolechalcogenolates

Full text of DOI:10.1023/A:1025569009652

Russian Journal of Organic Chemistry, Vol. 39, No. 2, 2003, pp. 284 286. Translated from Zhurnal Organicheskoi Khimii, Vol. 39, No. 2, 2003,
pp. 306 308.
Original Russian Text Copyright
2003 by Petrov, Androsov, Abramow, Dehaen.
SHORT
COMMUNICATIONS
4-(2-Aminophenyl)-1,2,3-thia- and -selenadiazoles
as a Source of 2-Indolechalcogenolates
M. L. Petrov, D. A. Androsov, M. A. Abramov, and W. Dehaen
St. Petersburg State Technological Institute, St. Petersburg, 198013 Russia
Received November 6, 2002
We recently developed a new preparation method
for 2-benzofuranchalcogenolates by cascade de-
composition reaction of 4-(2-hydroxyphenyl)-1,2,3-
thia- and -selenadiazoles initiated by weak bases [1,
2]. The 4-substituted 1,2,3-thia- and -selenadiazoles
treated with strong bases, as potassium ethylate,
butyllithium etc., commonly readily decompose with
nitrogen liberation affording alkynchalcogenolates
[3]. However the 4-(2-hydroxyphenyl)-1,2,3-thia- and
-selenadiazoles decomposed in the presence of so
weak a base as potassium carbonate (see scheme).
Therewith do not arise alkynchalcogenolates but
forms a 2-chalcogenolatebenzofuran anion resulting
from a cascade of reactions: starting with phenolate
formation till intramolecular cyclization involving the
hydroxy group and chalcogenoketene fragment.
and -selenadiazole (II) into 4-(2-aminophenyl-1,2,3-
thia- (III) and -selenadiazole (IV). 4-(2-Nitrophenyl)-
1,2,3-thiadiazole (I) was prepared by treating with
thionyl chloride of o-nitroacetophenone ethylcarb-
azone [4], and 4-(2-nitrophenyl)-1,2,3-selenadiazole
(II) was obtained by reaction of selenium(IV) oxide
with o-nitroacetophenone semicarbazone [5].
However 4-(2-aminophenyl-1,2,3-thia- (III) and
-selenadiazole (IV) did not decompose in the presence
of potassium carbonate as the corresponding hydroxy
derivatives [1, 2]. Only when treated with a strong
base, potassium tert-butylate, these thia- and -selena-
diazoles III, IV liberated nitrogen and transformed
into potassium 2-(2-aminophenyl)-ethynylchalco-
genolates (V, VI).
Potassium 2-(2-aminophenyl)ethynylthiolate under-
went intramolecular cyclization under the action of
ethanol and converted into potassium 2-indolethiolate.
Formation of the latter was confirmed by alkylation
with methyl iodide that furnished in good yield only
2-methylsulfanylindole (VII). Potassium 2-(2-amino-
phenyl)ethynylselenolate (VI) unlike the correspond-
ing thiolate underwent the intramolecular cyclization
only under treatment with acetic acid and immediately
X = S, Se.
Aiming at extension of this method to indole syn-
thesis we reduced 4-(2-nitrophenyl)-1,2,3-thia- (I)
1070-4280/03/3902-0284$25.00 2003 MAIK Nauka/Interperiodica

4-(2-AMINOPHENYL)-1,2,3-THIA- AND -SELENADIAZOLES
285
X = S (III, V, VII), Se (IV, VI, VIII).
afforded in good yield bis(2-indolyl) diselenide (VIII)
disregarding the presence of methyl iodide.
fraction with the product. On removing the solvent
we obtained 0.3 g (55%) of selenadiazole (IV),
red-green crystals with metallic luster, mp 58 60 C,
Rf 0.25 (eluent chloroform). 1H NMR spectrum
(CDCl3), , ppm: 5.05 s (NH2), 6.83 6.89 m (H3 and
H4), 7.26 t.d (H5), 7.51 d.d ( H6), 9.38 s (H5 Ht,
with satellites HSe, J2 42 Hz). 13C NMR spectrum
(CDCl3), C, ppm: 116.9 (C1), 117.5 (C3), 118.5
(C5), 130.4 (C6), 130.6 (C4), 139.4 (C5 Ht, CH, J1
190 Hz), 145.7 (C2), 163.1 (C4 Ht). Mass spectrum,
m/z (Irel, %): M+ 225 (2), [M N2]+ 197 (6),
[M N2 Se]+ 117 (100), 89 (48), 77 (16). Found, %:
C 42.39, 42.45; H 3.29, 3.42. C8H7N3Se. Calculated,
%: C 42.67, H 3.11.
4-(2-Aminophenyl)-1,2,3-thiadiazole (III). To a
dispersion of 2 g of 5% palladium on carbon in
160 ml of ethanol and 1.21 g (5.85 mmol) of
2-(2-nitrophenyl)-1,2,3-thiadiazole (I) was added
1.46 g (29.2 mmol) of hydrazine hydrate. The reac-
tion mixture was boiled for 24 h. On cooling to 20
25 C the reaction mixture was filtered, and the
solvent was removed under reduced pressure. The
resinous residue was subjected to chromatography on
a column 3 25 cm packed with silica gel Merck
70/230, eluent dichloromethane. On removing the
solvent we obtained 0.81 g (78%) of thiadiazole III.
1
Light-red plates, mp 84 85 C. H NMR spectrum
2-Methylsulfanylindole (VII). To a solution of
0.15 g (0.85 mmol) of 4-(2-aminophenyl)-1,2,3-
thiadiazole (III) in 20 ml of anhydrous THF was
added under argon 0.112 g (1 mmol) of potassium
tert-butylate. The reaction mixture was stirred for
15 min till gas evolution completely stopped, and
then 1 ml of ethanol was added. The reaction mixture
was stirred for 10 min more, and then was added
0.18 g (1.275 mmol) of methyl iodide. After stirring
of the reaction mixture for 1 h the solvent was
removed under reduced pressure. The residue was
subjected to chromatography on a column 3 30 cm
packed with silica gel Merck 70/230, eluent hexane
dichloromethane, 1: 3. On removing the solvent we
obtained 0.12 g (85%) of indole (VII). Light-brown
crystals, mp 47 48 C (mp 48 49 C [6]). 1H NMR
spectrum (CDCl3), , ppm: 2.44 s (SCH3), 6.52 s
(H3), 7.07 7.20m (H5 H7), 7.50d (H4), 8.00s (NH).
(CDCl3), , ppm: 5.53 s (NH2), 6.78 6.84 m (H3 and
H5), 7.21 t.d (H4), 7.49 d.d (H6), 8.62 s (H5 Ht).
13C NMR spectrum (CDCl3), , ppm: 114.4 (C1),
117.2, 117.9, 129.5, 130.4 (C5 Ht, CH, J1 190 Hz),
130.8, 145.5 (C2), 163.1 (C4 Ht). Mass spectrum,
m/z (Irel, %): M+ 177 (63), [M N2]+ 149 (78),
[M N2 S]+ 117 (100), 89 (33), 77 (26), 49 (32).
Found, %: C 54.41, 54.22; H 4.08, 4.23. C8H7N3S.
Calculated, %: C 54.23, H 3.95.
4-(2-Aminophenyl)-1,2,3-selenadiazole (IV).
A dispersion of 0.63 g (2.45 mmol) of 4-(2-nitro-
phenyl)-1,2,3-selenadiazole (II), 10 ml of glacial
acetic acid, and 0.69 g (12.32 mmol) of degreased
iron powder was stirred for 2.5 h at heating to 50
60 C in a flask protected from light. On cooling to
20 25 C the reaction product was extracted into
chloroform, and the extract was washed with water
to remove the acetic acid, The chloroform was
removed at reduced pressure, and the resinous residue
was subjected to chromatography on a column 3
20 cm packed with silica gel L 1000/1600, eluent
tetrachloromethane chloroform, 4: 1,collecting the
Bis(2-indolyl) diselenide (VIII). To a solution of
0.15 g (0.67 mmol) of 4-(2-aminophenyl)-1,2,3-
selenadiazole (IV) in 20 ml of anhydrous THF was
added under argon 0.09 g (0.8 mmol) of potassium
tert-butylate. The reaction mixture was stirred for
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 2 2003

286
PETROV et al.
15 min till gas evolution completely stopped, and
then 2 drops of acetic acid were added. The reaction
mixture was stirred for 10 min more, and then was
added 0.143 g (1 mmol) of methyl iodide. After
stirring of the reaction mixture for 1 h the solvent
was removed under reduced pressure. The residue
was subjected to chromatography on a column 3
20 cm packed with silica gel L 100/160, eluent
heptane dichloromethane, 3: 1. On removing the
solvent we obtained 0.08 g (62%) of diselenide VIII.
Light-orange crystals, mp 134 134.5 C, Rf 0.65
Kratos MS 890 instrument with direct admission of
the sample into the ion source, ionizing electrons
energy 70 eV, temperature of ionizing chamber
200 C. The mass of molecular ions in the mass
spectra is given for the principal isotope 80Se. The
reaction progress was monitored by TLC on Silufol
UV-254 plates, development under UV irradiation or
in iodine vapor. All solvents used in the study were
purified and dried by standard procedures.
The study was carried out under financial support
of the Russian Foundation for Basic Research (grant
no. 00-03-32740).
1
(eluent chloroform). H NMR spectrum (CDCl3), ,
ppm: 6.76 s (H3), 7.11 7.26 m (H5 and H6), 7.28 d
(H7), 7.59 d (H4), 8.19 s (NH). 13C NMR spectrum
(CDCl3), , ppm: 111.2 (C7), 113.1 (C2), 120.9 (C5),
121.2 (C4), 122.2 (C3), 124.1 (C6), 128.9 (C8), 138.9
(C1). Mass spectrum, m/z (Irel, %): M+ 392 (4),
[M 2H]+ 390 (9), [M Se]+ 312 (12), [M Se 2H]+
310 (34), [M 2Se]+ 232 (79), [M SeC8H7N]+ 196
(85), [C8H7N]+ 117 (100), [C8H7N NHCH]+ 89
(51). Found, %: C 49.21, 49.31; H 3.15, 3.27.
C16H12N2Se2. Calculated, %: C 48.98; H 3.06.
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Melting points were measured on Boetius heat-
1
ing block. H and 13C NMR spectra were registered
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 2 2003