Synthesis of selenosemicarbazides and 1,2,4-triazoles

Article abstract of DOI:10.3987/COM-06-10725

Acyl isoselenocyanates (1) were prepared from KSeCN and acyl chlorides in situ. Reactions of the acyl isoselenocyanates (1) with phenylhydrazine gave 2-phenyl-1,2-dihydro-3H-1,2,4-triazole-3-selones (2) and selenosemicarbazides (3). The obtained selenosem

Full text of DOI:10.3987/COM-06-10725

HETEROCYCLES, Vol. 68, No. 6, 2006
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HETEROCYCLES, Vol. 68, No. 6, 2006, pp. 1191 - 1200. © The Japan Institute of Heterocyclic Chemistry
Received, 10th March, 2006, Accepted, 24th April, 2006, Published online, 25th April, 2006. COM-06-10725
SYNTHESIS OF SELENOSEMICARBAZIDES AND 1,2,4-TRIAZOLES
Mamoru Koketsu,a,* Yusuke Yamamura,b and Hideharu Ishiharab,*
aDivision of Instrumental Analysis, Life Science Research Center, Gifu
University, Gifu 501-1193, Japan
bDepartment of Chemistry, Faculty of Engineering, Gifu University, Gifu
501-1193, Japan
koketsu@cc.gifu-u.ac.jp
Abstract – Acyl isoselenocyanates (1) were prepared from KSeCN and acyl
chlorides in situ. Reactions of the acyl isoselenocyanates (1) with
phenylhydrazine gave 2-phenyl-1,2-dihydro-3H-1,2,4-triazole-3-selones (2) and
selenosemicarbazides (3). The obtained selenosemicarbazides (3) were refluxed
in the presence of triethylamine in THF and trapped with alkyl halides to obtain
the corresponding 3-alkylseleno-1-phenyl-1H-1,2,4-triazoles (5) in moderate
yields.
INTRODUCTION
Several works on reactions of acyl isothiocyanates with hydrazines have been described in the literatures.1
4-Benzoyl-1-phenylthiosemicarbazide was obtained as the main product from the reaction of benzoyl
isothiocyanate with phenylhydrazine. Using an excess of hydrazine in an alcoholic solvent, a mixture of
triazolethione and benzoylhydrazide was afforded. With equimolar quantities of reactants, the reaction
gave 1,4-dibenzoylthiosemicarbazide and its salt with hydrazine. In contrast, reactions of acyl
isoselenocyanates with hydrazines have little been studied, though reactions with amines have been
reported.2 We confirmed that reactions of the acyl isoselenocyanates with phenylhydrazine afforded
2-phenyl-1,2-dihydro-3H-1,2,4-triazole-3-selones (2) and selenosemicarbazides (3). The treatment of
selenosemicarbazides (3) with alkyl halides in the presence of triethylamine gave the corresponding
3-alkylseleno-1-phenyl-1H-1,2,4-triazoles (5). Herein, we report the reactions of the acyl
isoselenocyanates with phenylhydrazine and synthesis of novel compounds (2) and (5).

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HETEROCYCLES, Vol. 68, No. 6, 2006
RESULTS AND DISCUSSION
Acyl isoselenocyanates (1) were prepared by reactions of acyl chloride with KSeCN as intermediate.3
Reactions of five kinds of acyl isoselenocyanates (1) with phenylhydrazine were carried out at room
temperature or -80°C for 1 h to afford 4-acyl-1-phenylselenosemicarbazides (3) as major products and
2-phenyl-1,2-dihydro-3H-1,2,4-triazole-3-selones (2)4 as minor ones, respectively. The reactions at -80°C
gave (3) in moderate yields. The reactions at room temperature afforded a mixture of products (2) and (3)
except the reaction with pivaloyl isoselenocyanate (Table 1). The structure of 3 was confirmed by X-Ray
crystal structure. In the case of acetyl, propionyl and butyryl isoselenocyanates, though the products (2)
and (3) were confirmed formation in the reaction mixture from the result of TLC monitoring, they could
not be isolated due to the decomposition during the process of purification by a silica gel column
chromatography. In the case of reactions of isothiocyanates with hydrazine, similar reactions afforded
different structures, 1,2,4-triazoline-3-thione1g or 1,2,4-triazoline-3-thiol as sole product.1b,1e,5 In the
present reaction, the selenosemicarbazides (3) were formed major product instead of cyclic compound (2).
Pedersen reported the preparation of selenosemicarbazides by the reaction of alkyl isoselenocyanates with
hydrazine in ethanol.6 But the reactions did not give cyclic compound, 1,2,4-triazoline-3-selone.
Table 1 Reaction of acyl isoselenocyanates with phenylhydrazine
O
Se
N
HN N
2
H
N
O
O
THF
PhNHNH2
1 h
R
Se
+ KSeCN
+
R
N
H
N
H
Ph
10 min
R
Cl
R
NCSe
Ph
1
3
Yield (%)a
R
Reaction Temp.
2
38
trace
5
trace
15
trace
20
trace
0
3
rt
-80°C
rt
-80°C
rt
-80°C
rt
-80°C
rt
23
48
5
32
27
41
16
17
30
12
p-CH3C6H4 (a)
C6H5 (b)
p-CH3OC6H4 (c)
p-ClC6H4 (d)
t-Bu (e)
-80°C
0
a: Isolated yield.
The X-Ray crystal structure of 1-phenyl-4-p-toluoylselenosemicarbazide (3a) was studied. An ORTEP
drawing, depicted in Figure 1, shows the crystal structure of 3a.7 The sum of the three angles around each
of the C1 and C2 atoms was 359.9°, the torsion angles of Se1-C1-N1-N2, Se1-C1-N3-C2, C1-N3-C2-O1
and C1-N3-C2-C3 were 3.0°, -166.9°, -1.3° and 179.2°, respectively, showing that the arrangement of

HETEROCYCLES, Vol. 68, No. 6, 2006
1193
C9
C7
C8
C6
C5
Se1
C1
N3
C2
C3
C4
N1
O1
N2
C10
C11
C15
C14
C12
C13
Figure 1 X-Ray crystal structure of 3a.
Table 2 Synthesis of 3-alkylseleno-1H-1,2,4-triazoles (5) from 1-phenyl-4-p-toluoylselenosemicarbazides (3a)
O
Se
H
N
H3C
N
Se
RX (4)
THF, Et3N
reflux, 1 h
N
H
N
H
Ph
R
reflux, 1 h
N N
H3C
Ph
3a
5
RX
Product
RX
Product
Yield
(%)a
Yield
(%)a
4
5
4
5
H3C
H3C
N
N
Se
Se
CH3
CH3
CH3
CH3I
5a 70
(CH3)2CHI
5d
61
N
N
N
N
Ph
Ph
Ph
H3C
H3C
N
N
Se
Se
Se
C2H5
C2H5I
5b 86
5c 71
cycloC6H11I
BnBr
5e
5f
55
61
N
N
N
N
N
Ph
Ph
H3C
H3C
N
N
Se
C3H7
n-C3H7I
N
N
N
N
Ph
H3C
H3C
N
N
Se
Se
C3H7
n-C3H7Br
5c 35
CH2=CHCH2Br
5g
59
N
N N
Ph
Ph
a: Isolated yield.

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HETEROCYCLES, Vol. 68, No. 6, 2006
N2, N1, C1, Se1, N3, C2 and C3 atoms was almost planar. The four C-N bond and a N-N bond lengths of
C10-N2 (1.406(9) Å) N1-N2 (1.404(7) Å), C1-N1 (1.292(9) Å), N3-C1 (1.402(8) Å) and C2-N3
(1.409(8) Å) in 3a are shorter than the typical value of 1.47 Å.8 These results can be attributed to the
delocalization of π electrons and lone pair electrons on nitrogen atoms. The nitrogen atoms in 3a has sp2
rather than sp3 character. Both inter- and intramolecular hydrogen bonds were observed (Figure 1). It is
shown that the flexibility of the molecule is restricted by H-bonding between hydrogen atom on N1 atom
and the O1 atom.
Cyclization of 1-phenyl-4-p-toluoylselenosemicarbazides (3a) in the presence of triethylamine was
proceeded then trapped by alkyl halides (4) at reflux and led to moderate yields of seven different
3-alkylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazoles
(5)
(Table
2).
In
the
case
of
1-alkyl-4-phenylthiosemicarbazides, similar reaction afforded 1,2,4-triazole-3-thiol.1b,1e In the present
reaction, the corresponding 1,2,4-triazole-3-selenol could not be isolated because of instability of the
selenol, therefore, alkyl halides (4) was used as a trapping reagent to afford cyclic compound (5). In order
to compare the structure of 2-phenyl-1,2-dihydro-3H-1,2,4-triazole-3-selones (2) with one of
3-alkylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazoles
(5),
reaction
of
2-phenyl-5-p-tolyl-1,2-dihydro-3H-1,2,4-triazole-3-selone (2a) with ethyl iodide was carried out. The
reaction afforded 3-ethylseleno-2-phenyl-5-p-tolyl-2H-1,2,4-triazole (6) in 61% yield (Scheme 1).
DMSO
rt, 1 h
N
N
N
N
+
C2H5I
Se
Se
C2H5
HN
N
(2 equiv.)
Ph
Ph
2a
6
61%
SCHEME 1
From the 1H-, 13C- and 77Se NMR data, the difference of structures between compounds (5) and (6) was
confirmed. The 13C NMR spectra of compound (6) shows the peaks for triazole ring carbons at 146.1 ppm
and 163.1 ppm, while the corresponding signals of compound (5b) are at 153.8 ppm and 155.0 ppm. The
77Se NMR chemical shifts of 5 and 6 are observed at 270.8 ppm and 290.7 ppm, respectively. The results
indicated that both compounds are different structures. From these results, the formations of products (2),
(3) and (5) could be explained by the mechanism described in Scheme 2. The formation of 2 is initiated
on the nucleophilic addition of phenylate amine of phenylhydrazine to isoselenocyanate carbon of 1,
affording the 2-phenyl-1,2-dihydro-3H-1,2,4-triazole-3-selones (2), whereas the formation of 3 is initiated
on the nucleophilic addition of terminal amine of the phenylhydrazine to isoselenocyanate carbon of 1,
affording the 1-phenylselenosemicarbazides (3). The formation of 5 is initiated on the intramolecular

HETEROCYCLES, Vol. 68, No. 6, 2006
1195
nucleophilic addition of nitrogen atom to carbonyl carbon of 3, affording the
3-alkylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazoles (5). Thus, products (2) and (5) are obtained as the
products bearing phenyl group at different position.
HO
R
H
N
O
Se
R
R
N
N
N
N
EtI
-H2O
Ph
Se
Et
Se
Se
R
N
H
N
HN
N
HN
N
NH2
Ph
Ph
O
Ph
2
6
H2NNHPh
R
N C Se
+
O
Se
H
N
1
R
N
H
N
H
Ph
3
O
Se
HO
H
N
H
N
R
R
N
N
N
-H2O
R'X (4)
R
R
N
H
N
H
Ph
+
SeR'
Et3N
Se
Se
N
N
N
N
H
N
H
Ph
Ph
Ph
3
5
SCHEME 2
In conclusion, reactions of the acyl isoselenocyanates (1) with phenylhydrazine gave
1,2-dihydro-3H-1,2,4-triazole-3-selones (2) and selenosemicarbazides (3), respectively. The obtained
selenosemicarbazides (3) were used as starting materials for the synthesis of heterocycles to afford the
corresponding
3-alkylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazoles
(2) was used for
(5)
whereas
synthesis of
1,2-dihydro-3H-1,2,4-triazole-3-selones
the
3-ethylseleno-2-phenyl-5-p-tolyl-2H-1,2,4-triazole (6).
EXPERIMENTAL
General
The 77Se chemical shifts were expressed in ppm deshielded with respect to neat Me2Se in CDCl3 or
DMSO.
Synthesis
of
2-phenyl-5-p-tolyl-1,2-dihydro-3H-1,2,4-triazole-3-selone
(2a)
and
1-phenyl-4-p-toluoylselenosemicarbazide (3a). To a solution of KSeCN (0.28 g, 2 mmol) in dry THF (5
mL) p-toluoyl chloride (0.13 mL, 1 mmol) in dry THF (5 mL) was added dropwise for 5 min at ambient
temperature with stirring. The mixture was stirred for 10 min. Phenylhydrazine (0.10 mL, 1 mmol) in dry
THF (5 mL) was added to the above mixture and stirred for 15 min. The reaction mixture was extracted
with dichloromethane and washed with water. The combined organic layer was dried over sodium sulfate
and evaporated to dryness. The residue was diluted with ether and the solid triazole (2a) (0.12 g, 38 %)

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HETEROCYCLES, Vol. 68, No. 6, 2006
1
was recovered by filtration. mp 160.1-161.0ºC; IR (KBr): 3056, 1598, 1505, 1463, 1243 cm-1; H NMR
(500 MHz, DMSO): δ 2.38 (s, 3H), 7.36 (d, 2H, J = 7.6 Hz), 7.49 (t, 1H, J = 7.6 Hz), 7.57 (t, 2H, J = 7.6
13
Hz), 7.93 (d, 2H, J = 7.6 Hz), 8.04 (d, 2H, J = 7.6 Hz), 14.7 (brs, 1H); C NMR (125 MHz, DMSO): δ
21.1, 121.7, 124.7, 126.2, 128.3, 128.7, 129.7, 138.1, 141.3, 151.5, 158.5; 77Se NMR (75 MHz, DMSO):
δ 88.7; MS (FAB): m/z = 316 [M+1]+; HRMS: m/z = 315.0275, Calcd. for C15H13N3Se, Found 315.0316.
The ether layer was evaporated to dryness. The residue was purified by flash column chromatography on
silica gel using n-hexane: dichloromethane (1:1) as eluent to give 3a (0.08 g, 23%). mp 137.1-139.8ºC; IR
(KBr): 3230, 1670, 1604, 1492, 1264 cm-1; 1H NMR (500 MHz, CDCl3): δ 2.46 (s, 3H), 6.96 (d, 2H, J =
8.0 Hz), 7.01 (t, 1H, J = 7.5 Hz), 7.26-7.34 (m, 4H), 7.43 (brs, 1H), 7.78 (d, 2H, J = 8.0 Hz), 9.40 (brs,
1H), 12.8 (brs, 1H); 13C NMR (125 MHz, CDCl3): δ 21.7, 114.6, 122.5, 127.7, 127.9, 129.4, 129.9,
77
145.09, 145.14, 166.8, 177.5; Se NMR (75 MHz, CDCl3): δ 296.8; MS (CI): m/z = 334 [M+1]+; Anal.
Calcd for C15H15N3OSe: C, 54.22; H, 4.55; N, 12.65. Found: C, 53.80; H, 4.64; N, 12.50.
2,5-Diphenyl-1,2-dihydro-3H-1,2,4-triazole-3-selone (2b) mp 151.7-152.0ºC; IR (KBr): 3060, 1560,
1
1470, 1240 cm-1; H NMR (500 MHz, DMSO): δ 7.47 (t, 1H, J = 7.7 Hz), 7.51-7.59 (m, 5H), 7.98-8.05
(m, 4H), 14.7 (brs, 1H); 13C NMR (125 MHz, DMSO): δ 124.5, 124.9, 126.3, 128.5, 128.7, 129.2, 131.3,
138.1, 151.5, 158.7; 77Se NMR (75 MHz, DMSO): δ 89.8; MS (FAB): m/z = 302 [M+1]+; HRMS: m/z =
301.0118, Calcd. for C14H11N3Se, Found 301.0129.
4-Benzoyl-1-phenylselenosemicarbazide (3b) mp 123.4-125.7ºC; IR (KBr): 3181, 1679, 1600, 1514,
1474, 1263 cm-1; 1H NMR (500 MHz, CDCl3): δ 6.95 (d, 2H, J = 7.6 Hz), 7.00 (t, 1H, J = 7.6 Hz), 7.29 (t,
2H, J = 7.6 Hz), 7.44 (d, 1H, J = 8.4 Hz), 7.50 (t, 2H, J = 7.6 Hz), 7.63 (t, 1H, J = 7.6 Hz), 7.86 (d, 2H, J
= 7.6 Hz), 9.45 (brs, 1H), 12.8 (d, 2H, J = 7.6 Hz); 13C NMR (125 MHz, CDCl3): δ 114.7, 122.6, 127.7,
77
129.3, 129.4, 130.8, 134.0, 145.1, 166.9, 177.4; Se NMR (75 MHz, CDCl3): δ 303.4; MS (EI): m/z =
319 [M]+; Anal. Calcd for C14H13N3OSe: C, 52.84; H, 4.12; N, 13.20. Found: C, 52.54; H, 4.21; N, 13.16.
5-p-Methoxyphenyl-2-phenyl-1,2-dihydro-3H-1,2,4-triazole-3-selone (2c) mp 146.1-147.6ºC; IR
(KBr): 3006, 1614, 1508, 1458, 1241 cm-1; 1H NMR (500 MHz, DMSO): δ 3.84 (s, 3H), 7.12 (d, 2H, J =
8.6 Hz), 7.48 (t, 1H, J = 7.7 Hz), 7.56 (t, 2H, J = 7.7 Hz), 7.98 (d, 2H, J = 8.6 Hz), 8.03 (d, 2H, J = 7.7
Hz), 14.3 (brs, 1H); 13C NMR (125 MHz, DMSO): δ 55.5, 114.7, 116.7, 124.8, 128.0, 128.3, 128.7, 138.1,
151.4, 158.3, 161.5; 77Se NMR (75 MHz, DMSO): δ 87.2; MS (FAB): m/z = 332 [M+1]+; HRMS: m/z =
331.0224, Calcd. for C15H13N3OSe, Found 331.0212.
4-p-Anisoyl-1-phenylselenosemicarbazide (3c) mp 152.1-153.6ºC; IR (KBr): 3237, 1665, 1602, 1498,
1254 cm-1; 1H NMR (500 MHz, CDCl3): δ 3.88 (s, 3H), 6.93-7.03 (m, 5H), 7.29 (t, 2H, J = 7.7 Hz), 7.42
13
(d, 1H, J = 7.7 Hz), 7.84 (d, 2H, J = 8.6 Hz), 9.32 (brs, 1H), 12.8 (brs, 1H, J = 7.6 Hz); C NMR (125
MHz, CDCl3): δ 55.6, 114.5, 114.6, 122.4, 122.6, 129.4, 129.9, 145.2, 164.2, 166.3, 177.6; 77Se NMR (75

HETEROCYCLES, Vol. 68, No. 6, 2006
1197
MHz, CDCl3): δ 293.9; MS (EI): m/z = 349 [M]+; Anal. Calcd for C15H15N3O2Se: C, 51.73; H, 4.34; N,
12.07. Found: C, 51.50; H, 4.40; N, 12.01.
5-p-Chlorophenyl-2-phenyl-1,2-dihydro-3H-1,2,4-triazole-3-selone (2d) mp 167.5-169.0ºC; IR (KBr):
3062, 1608, 1500, 1454, 1239 cm-1; 1H NMR (500 MHz, DMSO): δ 7.50 (t, 1H, J = 7.9 Hz), 7.57 (t, 2H,
J = 7.9 Hz), 7.65 (dd, 2H, J = 1.8, 8.8 Hz), 8.01 (d, 2H, J = 7.9 Hz), 8.04 (d, 2H, J = 8.8 Hz), 14.8 (brs,
1H); 13C NMR (125 MHz, DMSO): δ 124.5, 124.9, 126.3, 128.5, 128.8, 129.2, 131.3,138,1, 151.5, 158.8;
77Se NMR (75 MHz, DMSO): δ 88.7; MS (FAB): m/z = 335 [M+1]+; HRMS: m/z = 334.9728, Calcd. for
C14H10N3ClSe, Found 334.9759.
4-p-Chlorobenzoyl-1-phenylselenosemicarbazide (3d) mp 137.2-138.9ºC; IR (KBr): 3178, 1670, 1595,
1259 cm-1; 1H NMR (500 MHz, CDCl3): δ 6.95 (d, 2H, J = 7.6 Hz), 7.02 (t, 1H, J = 7.6 Hz), 7.30 (t, 2H, J
= 7.6 Hz), 7.42 (brs, 1H), 7.49 (t, 2H, J = 8.4 Hz), 7.82 (d, 2H, J = 8.4 Hz), 9.41 (brs, 1H), 12.7 (brs, 1H);
13C NMR (125 MHz, CDCl3): δ 114.6, 122.6, 129.09, 129.14, 129.4, 129.6, 140.6, 145.0, 165.9, 177.2;
77Se NMR (75 MHz, CDCl3): δ 309.3; MS (CI): m/z = 354 [M+1]+; Anal. Calcd for C14H12N3OClSe: C,
47.68; H, 3.43; N, 11.91. Found: C, 47.35; H, 3.49; N, 11.80.
1-Phenyl-4-pivaloylselenosemicarbazide (3e) mp 84.4-85.8ºC; IR (KBr): 3224, 1680, 1502, 1187 cm-1;
1H NMR (500 MHz, CDCl3): δ 1.30 (s, 9H), 6.91 (d, 2H, J = 7.9 Hz), 6.99 (t, 1H, J = 7.9 Hz), 7.28 (t, 2H,
13
J = 7.9 Hz), 7.40 (brs, 1H), 8.75 (brs, 1H), 12.6 (brs, 1H); C NMR (125 MHz, CDCl3): δ 26.8, 39.7,
114.6, 122.4, 129.3, 145.0, 177.1, 179.3; 77Se NMR (75 MHz, CDCl3): δ 288.3; MS (CI): m/z = 300
[M+1]+; Anal. Calcd for C12H17N3OSe: C, 48.33; H, 5.75; N, 14.09. Found: C, 47.98; H, 5.71; N, 13.96.
Synthesis of 3-methylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazole (5a) To a solution of 3a (0.17 g, 0.5
mmol) in dry THF (5 mL), triethylamine (0.07 mL, 0.5 mmol) was added and the reaction mixture was
refluxed for 1 h. MeI (4a) (0.06 mL, 1 mmol) was added to the reaction mixture, and the mixture was
stirred at reflux for 1h. The reaction mixture was extracted with diethyl ether and washed with saturated
NaCl solution. The combined organic layer was dried over sodium sulfate and evaporated to dryness. The
residue was purified by flash column chromatography on silica gel using n-hexane: ether (2:1) as eluent
1
to give 5a (0.11 g, 70%). mp 113.0-114.1ºC; IR (KBr): 1501, 1459, 1260 cm-1; H NMR (500 MHz,
CDCl3): δ 2.34 (s, 3H), 2.56 (s, 3H, 2J 77Se-1H = 11.5 Hz), 7.12 (d, 2H, J = 8.0 Hz), 7.32-7.44 (m, 7H); 13C
NMR (125 MHz, CDCl3): δ 6.1, 21.4, 124.6, 125.3, 128.71, 128.75, 129.2, 129.3, 138.1, 140.3, 154.2,
77
155.2; Se NMR (75 MHz, CDCl3): δ 158.7; MS (EI): m/z = 329 [M]+; Anal. Calcd for C16H15N3Se: C,
58.54; H, 4.61; N, 12.80. Found: C, 58.61; H, 4.85; N, 12.52.
3-Ethylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazole (5b) mp 95.1-95.4ºC; IR (KBr): 1496, 1450, 1258
cm-1; 1H NMR (500 MHz, CDCl3): δ 1.60 (t, 3H, J = 7.9 Hz), 2.34 (s, 3H), 3.23 (q, 2H, J = 7.9 Hz), 7.12
13
(d, 2H, J = 7.9 Hz), 7.32-7.43 (m, 7H); C NMR (125 MHz, CDCl3): δ 16.0, 20.4, 21.3, 124.6, 125.3,

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HETEROCYCLES, Vol. 68, No. 6, 2006
128.7, 129.16, 129.24, 138.1, 140.2, 153.8, 155.0; 77Se NMR (75 MHz, CDCl3): δ 270.8; MS (EI): m/z =
343 [M]+; Anal. Calcd for C17H17N3Se: C, 59.65; H, 5.01; N, 12.28. Found: C, 59.24; H, 5.09; N, 12.02.
3-Propylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazole (5c) mp 67.6-68.5ºC; IR (KBr): 1495, 1451, 1256
cm-1; 1H NMR (500 MHz, CDCl3): δ 1.06 (t, 3H, J = 7.5 Hz), 1.90 (sixtet, 2H, J = 7.5 Hz), 2.34 (s, 3H),
3.22 (t, 2H, J = 7.5 Hz), 7.12 (d, 2H, J = 7.5 Hz), 7.31-7.43 (m, 7H); 13C NMR (125 MHz, CDCl3): δ 14.4,
77
21.3, 23.8, 28.8, 124.6, 125.2, 128.65, 128.70, 129.1, 129.2, 138.1, 140.2, 154.0, 155.0; Se NMR (75
MHz, CDCl3): δ 234.1; MS (EI): m/z = 357 [M]+; Anal. Calcd for C18H19N3Se: C, 60.67; H, 5.37; N,
11.79. Found: C, 60.55; H, 5.58; N, 11.44.
3-Isopropylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazole (5d) mp 91.4-92.5ºC; IR (KBr): 1494, 1433,
1252 cm-1; 1H NMR (500 MHz, CDCl3): δ 1.59 (d, 3H, J = 6.9 Hz), 1.62 (d, 3H, J = 6.9 Hz), 2.35 (s, 3H),
13
3.91-4.01 (m, 1H), 7.12 (d, 2H, J = 7.5 Hz), 7.32-7.44 (m, 7H); C NMR (125 MHz, CDCl3): δ 21.4,
24.6, 34.0, 124.6, 125.3, 128.7, 128.8, 129.2, 129.3, 138.1, 140.3, 154.0, 155.0; 77Se NMR (75 MHz,
CDCl3): δ 357.6; MS (EI): m/z = 357 [M]+; Anal. Calcd for C18H19N3Se: C, 60.67; H, 5.37; N, 11.79.
Found: C, 60.46; H, 5.55; N, 11.59.
3-Cyclohexylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazole (5e) mp 112.7-114.1ºC; IR (KBr): 1500, 1449,
1
1250 cm-1; H NMR (500 MHz, CDCl3): δ 1.30-1.49 (m, 3H), 1.58-1.65 (m, 1H), 1.69-1.81 (m, 4H),
2.18-2.26 (m, 2H), 2.35 (s, 3H), 3.82-3.91 (m, 1H), 7.12 (d, 2H, J = 8.0 Hz), 7.33-7.44 (m, 7H); 13C NMR
(125 MHz, CDCl3): δ 21.4, 25.7, 26.6, 34.4, 43.1, 124.6, 125.3, 128.7, 128.8, 129.17, 129.24, 138.1,
140.2, 153.8, 155.0; MS (EI): m/z = 397 [M]+; Anal. Calcd for C21H23N3Se: C, 63.63; H, 5.85; N, 10.60.
Found: C, 63.38; H, 6.01; N, 10.32.
3-Benzylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazole (5f) mp 84.6-86.0ºC; IR (KBr): 1594, 1498, 1453,
1255 cm-1; 1H NMR (500 MHz, CDCl3): δ 2.35 (s, 3H), 4.49 (s, 2H), 7.12 (d, 2H, J = 8.0 Hz), 7.19-7.46
13
(m, 12H); C NMR (125 MHz, CDCl3): δ 21.4, 30.1, 124.5, 125.3, 127.0, 128.5, 128.7, 128.8, 129.1,
77
129.2, 129.3, 138.1, 138.3, 140.4, 154.2, 155.1; Se NMR (75 MHz, CDCl3): δ 307.9; MS (EI): m/z =
405 [M]+; Anal. Calcd for C22H19N3Se: C, 65.35; H, 4.74; N, 10.39. Found: C, 64.95; H, 4.99; N, 10.09.
3-Allylseleno-1-phenyl-5-p-tolyl-1H-1,2,4-triazole (5g) mp 102.2-103.7ºC; IR (KBr): 1496, 1450, 1256
cm-1; 1H NMR (500 MHz, CDCl3): δ 2.35 (s, 3H), 3.88 (d, 2H, J = 7.5 Hz), 5.04 (d, 1H, J = 9.7 Hz), 5.24
(d, 1H, J = 16.6 Hz), 6.08-6.18 (m, 1H), 7.13 (d, 2H, J = 8.0 Hz), 7.32-7.44 (m, 7H); 13C NMR (125 MHz,
CDCl3): δ 21.4, 28.9, 117.4, 124.5, 125.3, 128.7, 128.8, 129.2, 129.3, 134.5, 138.1, 140.3, 153.6, 155.1;
77Se NMR (75 MHz, CDCl3): δ 274.5; MS (EI): m/z = 355 [M]+.
3-Ethylseleno-2-phenyl-5-p-tolyl-2H-1,2,4-triazole (6) mp 85.0-86.5ºC; IR (KBr): 1595, 1504, 1335
cm-1; 1H NMR (500 MHz, CDCl3): δ 1.58 (t, 3H, J = 7.5 Hz), 2.39 (s, 3H), 3.35 (q, 2H, J = 7.5 Hz), 7.25
(d, 2H, J = 8.0 Hz), 7.42 (t, 1H, J = 7.5 Hz), 7.50 (t, 2H, J = 7.5 Hz), 7.61 (d, 2H, J = 7.5 Hz), 8.06 (d, 2H,

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13
J = 8.0 Hz); C NMR (125 MHz, CDCl3): δ 15.6, 21.4, 23.1, 124.1, 126.3, 128.0, 128.6, 129.2, 129.3,
137.8, 139.2, 146.1, 163.1; 77Se NMR (75 MHz, CDCl3): δ 290.7; MS (EI): m/z = 343 [M]+; Anal. Calcd
for C17H17N3Se: C, 59.65; H, 5.01; N, 12.28. Found: C, 59.49; H, 5.16; N, 11.91.
ACKNOWLEDGEMENTS
This work was supported by a Grant-in-Aid for Science Research from the Ministry of Education, Culture,
Sports, Science and Technology of Japan (No. 15550030 and 17550099) to which we are grateful.
REFERENCES AND NOTES
1. (a) A. R. Katritzky, X. Cai, and B. V. Rogovoy, J. Comb. Chem., 2003, 5, 392. (b) J. M. Kane, M. W.
Dudley, S. M. Sorensen, and F. P. Miller, J. Med. Chem., 1988, 31, 1253. (c) L. L. Whitfield, Jr. and
E. P. Papadopoulos, J. Heterocyclic Chem., 1981, 18, 1197. (d) M. Uher, M. Bosansky, S. Kovac,
and A. Martvon, Coll. Czech. Chem. Commun., 1980, 45, 2804. (e) P. Kutschy, P. Kristian, M.
Dzurilla, and J. Kovac, Coll. Czech. Chem. Commun., 1980, 45, 1692. (f) M. Kulka, Can. J. Chem.,
1980, 58, 2044; M. Augustin, M. Richter, and S. Salas, J. prakt. Chem., 1980, 322, 55. (g) Y.
Ohshiro, N. Ando, M. Komatsu, and T. Agawa, Synthesis, 1985, 276.
2. Reactions of acyl isoselenocayanates with amines have been reported: (a) J. Sibor, D. Zurek, R.
Marek, M. Kuty, O. Humpa, J. Marek, and P. Pazdera, Coll. Czech. Chem. Commun., 1999, 64, 1673.
(b) Z. J. Witczak, Tetrahedron, 1985, 41, 4781. (c) P. Kristian, D. Koscik, and J. Gonda, Coll. Czech.
Chem. Commun., 1983, 48, 3567.
3. (a) G. L. Sommen, A. Linden, and H. Heimgartner, Heterocycles, 2005, 65, 1903. (b) Y. Zhou and H.
Heimgartner, Helv. Chim. Acta, 2000, 83, 539. (c) T. Kanda, H. Aoki, K. Mizoguchi, S. Shiraishi, T.
Murai, and S. Kato, Organometallics, 1996, 15, 5753.
4. There are only few reports regarding triazoleselones: (a) D. Enders, K. Breuer, U. Kallfass, and T.
Balensiefer, Synthesis, 2003, 1292. (b) P. F. De Athayde-Filho, A. M. Simas, S. M. Cruz Goncalves,
and J. Miller, Phosphorus, Sulfur, Silicon, 2000, 161, 115. (c) W. Bocian, J. Jazwinski, and J. L.
Stefaniak, Pol. J. Chem., 1995, 69, 85. (d) E. Bulka and D. Ehlers, J. prakt. Chem., 1973, 315, 155.
5. A. Baxter, C. Bennion, J. Bent, K. Boden, S. Brough, A. Cooper, E. Kinchin, N. Kindon, T.
McInally, M. Mortimore, B. Roberts, and J. Unitt, Bioorg. Med. Chem. Lett., 2003, 13, 2625.
6. C. T. Pedersen, Acta Chem. Scand., 1963, 17, 1459.
7. Crystallographic data for the structural analysis have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication, CCDC No. 297505 for 3a. Copies of
this information can be obtained, free of charge, on application to CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (fax: + 44 1233 336033 or e-mail: deposit@ccdc.cam.ac.uk).

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8. (a) M. M. Muir, C. Osvaldo, L. Bernard, and J. A. Muir, J. Crystallogr. Spectrosc. Res., 1992, 22,
271. (b) E. Ruiz, X. Tang, Y. J. Li, and M. M. Muir, J. Crystallogr. Spectrosc. Res., 1993, 23, 791.
(c) Y. Zhou, A. Linden, and H. Heimgartner, Helv. Chim. Acta, 2000, 83, 1576. (d) M. Koketsu, F.
Nada, and H. Ishihara, Synthesis, 2002, 195. (e) M. Koketsu and H. Ishihara, Curr. Org. Chem.,
2003, 7, 175.