Synthesis of bis(2,4-diarylimidazol-5-yl) diselenides from N-benzylbenzimidoyl isoselenocyanates

Article abstract of DOI:10.1002/1522-2675(200204)85:4<1102::AID-HLCA1102>3.0.CO;2-T

The reaction of N-benzylbenzamides 6 with SOCl₂ under reflux gave the corresponding N-benzylbenzimidoyl chlorides 7. Further treatment with KSeCN in dry acetone yielded imidoyl isoselenocyanates 3 (Scheme 2). These compounds, obtained in satisfying yields, proved to be stable enough to be purified and analyzed. Reaction of 3 with morpholine in dry acetone led to the corresponding selenourea derivatives 8. On treatment with Et₃N, the 4-nitrobenzyl derivatives of type 3 were transformed into bis(2,4-diarylimidazol-5-yl) diselenides 9 (Scheme 3). This transformation takes place only when the benzyl residue bears an NO₂ group and the phenyl group is not substituted with a strong electron-donating group. A reaction mechanism for the formation of 9 is proposed in Scheme 4. The key structures have been established by X-ray crystallography.

Full text of DOI:10.1002/1522-2675(200204)85:4<1102::AID-HLCA1102>3.0.CO;2-T

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Helvetica Chimica Acta Vol. 85 (2002)
Synthesis of Bis(2,4-diarylimidazol-5-yl) Diselenides from
N-Benzylbenzimidoyl Isoselenocyanates
by Plamen K. Atanassov1), Yuehui Zhou2), Anthony Linden, and Heinz Heimgartner*
Organisch-chemisches Institut der Universit‰t Z¸rich, Winterthurerstrasse 190, CH-8057 Z¸rich
The reaction of N-benzylbenzamides 6 with SOCl2 under reflux gave the corresponding N-benzylbenzim-
idoyl chlorides 7. Further treatment with KSeCN in dry acetone yielded imidoyl isoselenocyanates 3 (Scheme 2).
These compounds, obtained in satisfying yields, proved to be stable enough to be purified and analyzed.
Reaction of 3 with morpholine in dry acetone led to the corresponding selenourea derivatives 8. On treatment
with Et3N, the 4-nitrobenzyl derivatives of type 3 were transformed into bis(2,4-diarylimidazol-5-yl) diselenides
9 (Scheme 3). This transformation takes place only when the benzyl residue bears an NO2 group and the phenyl
group is not substituted with a strong electron-donating group. A reaction mechanism for the formation of 9 is
proposed in Scheme 4. The key structures have been established by X-ray crystallography.
1. Introduction.
In recent years, interest in the chemistry of Se-containing
compounds has increased remarkably due to their chemical properties [1 4] and
biological activities [5 7]. Although selenium was obtained for the first time by
Berzelius in 1817 [8] and the preparation of the first organoselenium compound, i.e.,
ethylselenol, by Wˆhler and Siemens dates from 1847 [9], most progress in the area of
the synthetic organic chemistry of Se was accomplished more than 100 years later, in
contrast to the chemistry of O- and S-containing organic molecules, which is much
better developed. Currently, organic Se compounds are frequently used in organic
synthesis in many different ways (cf. [10 14] and refs. cited therein).
The properties of Se-containing compounds mostly resemble those of their S
analogues, but some remarkable differences are also observed. Organic Se compounds
are, in some cases, oxidation- and photo-sensitive, and appear, in general, to be less
stable than their S analogues. Furthermore, they are often evil-smelling and very toxic.
Therefore, new approaches to organic Se compounds by using more stable and less
toxic starting materials are an attractive goal. Such products with the potential for use
in the syntheses of Se compounds appear to be aroyl isoselenocyanates 1, which are
easily prepared from aroyl chlorides and KSeCN [15] (cf. [16 18]).
Unfortunately, the intermediates of type 1 could not be isolated in a pure state.
They were obtained as mixtures of monomers and oligomers in low yield, e.g., as
precursors of selenoureas [19][20]. For the preparation of Se heterocycles, N-
phenylbenzimidoyl isoselenocyanates of type 2 were also used [21][22]. They are
relatively stable and, in some reactions, led to products in high yields and of high purity.
In the present research project, we have used N-benzylbenzimidoyl isoselenocyanates 3
1
)
)
Part of the planned Ph.D. thesis, Universit‰t Z¸rich.
Postdoctoral stay at the University of Z¸rich (08.98 12.99).
2

Helvetica Chimica Acta Vol. 85 (2002)
1103
R2
R2
O
N
N
N
C
Se
N
C
Se
N
C
Se
R1
R1
R
1
2
3
as starting materials. They are conveniently prepared from benzylamines and aroyl
chlorides and are stable compounds, too. They proved to be suitable intermediates for
the syntheses of organic Se compounds, e.g., bis(imidazol-5-yl) diselenides.
Diselenides belong to the basic reagents in the organic chemistry of Se [2 4]. The
most important routes to these compounds are the treatment of organic halides with
metal diselenides or reactions that lead to selenols that are further oxidized to give
diselenides (Scheme 1) [23 28] (cf. also [29 35]).
Scheme 1
+
R
Br
R
Se Se
R
2
M2Se2
R
M
Se
2
2
+
[O]
R
Se Se
R
R
SeH
2
NaOH
R
SeCN
2
Diaryl diselenides are of importance in organic as well as in medicinal chemistry.
After in situ oxidation to electrophilic or reduction to nucleophilic intermediates, they
have been extensively used in the synthesis of organic compounds, e.g., as auxiliary
agents to introduce new functional groups under mild conditions [36] or to generate
new stereogenic centers in substrates by means of chiral diselenides [3a]. On the other
hand, bis(imidazol-2-yl) disulfides have been used as an auxiliary in cyclizations to give
macrolides [37] and have also been found to be effective against certain cancer cell
lines [38]. Recently, the highly cytotoxic imidazol-5-yl disulfide polycarpine was
isolated from the Pacific Ocean ascidians Polycarpa aurata and Polycarpa clavata [39],
and the synthesis of the compound was carried out [40]. Furthermore, as mimics of
glutathione peroxidase, the antioxidant activity of aryl diselenides with substituents
containing N- or O-atoms in the proximity of the Se-atom is of current interest [41].

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Helvetica Chimica Acta Vol. 85 (2002)
Some diselenides act as immunostimulants by the induction of cytokines [42], and they
are promising candidates for a new strategy for the chemotherapy of AIDS [43].
In the present paper, we report a practical and efficient method for the preparation
of bis(imidazol-5-yl) diselenides from easily accessible imidoyl isoselenocyanates,
which was developed as part of our efforts to create less-toxic and stable isoseleno-
cyanates as starting materials for Se-containing heterocycles (cf. [20][22]). A similar
method has been used previously for the synthesis of bis[(arylsulfonyl)imidazol-5-yl]
disulfides [44].
2. Results and Discussion. The N-benzylbenzamides 6a l, which are starting
materials for the synthesis of N-benzylbenzimidoyl chlorides 7, were conveniently
prepared by slow addition of benzoyl chlorides 4 to a cooled solution (ca. 08) of the
appropriate benzylamine 5 in pyridine under stirring. Then, the mixture was heated to
908 for 1 h, and the solution was poured into ice-water. The precipitate was washed with
cold H2O and recrystallized from EtOH[45] to give 6 (Scheme 2 and Table 1).
A mixture of 6 and 2 3 equiv. of SOCl2 was then heated to reflux until the
evolution of SO2 ceased (ca. 3 h). The excess of SOCl2 was evaporated, and the crude
imidoyl chloride 7 was dried (24 h, in vacuo)3). This material was dissolved in dry
acetone, and the solution was added under stirring to a freshly prepared solution of
1.1 equiv. of KSeCN in dry acetone at room temperature. After 30 min, the mixture was
poured slowly into ice-water and the precipitate was filtered and air-dried. The crude
product was recrystallized from CH2Cl2/hexane to give imidoyl isoselenocyanate 3 as
yellow crystals4) (Scheme 2 and Table 1). The structures of the isoselenocyanates 3
Scheme 2
O
O
N
Cl
Pyridine
-HCl
H2N
H
+
R2
R1
R1
R2
4
5
6
SOCl2 -SO2
-HCl
R2
Cl
N
KSeCN
N
Acetone
-KCl
R2
R1
N
C
Se
R1
3
7
Surprisingly, no imidoyl chloride was formed in the cases of R1 ˆ Cl or NO2 and R2 ˆ NO2.
3
4
)
)
During crystallization, the product partially decomposed.

Helvetica Chimica Acta Vol. 85 (2002)
1105
Table 1. Yields [%] of the Prepared Amides 6, Isoselenocyanates 3, Selenoureas 8, and Diselenides 9
R1
R2
6
3
8
9
a
b
c
d
e
f
g
h
i
HNO
Br
Cl
F
Me
MeO
CN
CO2Me
NO2
Cl
65
72
67
55
82
78
60
63
28.2
85
80
51.2
47.3
37.8
73.7
43.1
17.6
58.6
33.8
99.5
48.8
58.3
36.9
35.8
37.5
2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
H83
Cl
64.5
75.0
75.6
51.4
90.0
47.0
53.2
46.3
42.6
k
l
55.5
81.0
CN
Cl
have been established on the basis of their spectroscopic and analytical data and, in the
case of 3b, by an X-ray crystal-structure determination (Fig. 1).
The bond lengths in the NˆCˆSe group are very short (1.173(3) ä for CˆN and
1.720(3) ä for CˆSe) and indicate significant p-interactions between these atoms. The
cumulated p-system is further supported by the very large bond angle (176.6(2)8)
involving the N-atom of this group. The molecule has two planar sections: the
nitrophenyl group up to C(5) and the bromophenyl group right through to C(5) and
including N(2)5). These two planes intersect at an angle of 18.60(8)8. The atom C(1)
Fig. 1. ORTEP Plot [46] of the molecular structure of 3b (arbitrary numbering of the atoms; 50% probability
ellipsoids)
5
)
Arbitrary numbering of the atoms used in Fig. 1.

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Helvetica Chimica Acta Vol. 85 (2002)
deviates only slightly from the second plane (0.019(3) ä), whereas the deviation of the
Se-atom is significant (0.115(1) ä).
When 1.1 equiv. of morpholine were added to a stirred solution of 3 in acetone at
room temperature, the yellow color of the solution changed to dark brown. According
to TLC, the reaction was complete within 15 30 min. After ice-water was added to the
mixture, a yellow precipitate was formed. The crude product was recrystallized from
CH2Cl2/hexane, and the structures of the selenourea derivatives 8 were determined
from their spectroscopic data and elemental analyses (Scheme 3 and Table 1). In the
case of 8b, the structure was established by X-ray crystallography (Fig. 2).
The crystal structure of 8b shows that the NHgroup is adjacent to the benzylic CH 2
group, and the CˆN bond is adjacent to the Se-bearing C-atom. The asymmetric unit
also contains one half of a benzene molecule, which sits across a center of inversion.
The NHgroup forms an intermolecular H-bond with the Se-atom of a neighboring
molecule, thereby linking the molecules into infinite one-dimensional chains that run
parallel to the b-axis and have a graph-set motif [47] of C(6).
Scheme 3
R2
R2
HN
O
N
HN
Se
N
C
Se
N
Acetone
N
R1
R1
O
3
8
Et3N
Acetone
R2 = NO2
R2
NO2
N
N
Se
Se
N
H
N
H
N
2
R1
O
R1
9
8'

Helvetica Chimica Acta Vol. 85 (2002)
1107
Fig. 2. ORTEP Plot [46] of the molecular structure of 8b (arbitrary numbering of the atoms; 50% probability
ellipsoids; the solvent molecule has been omitted for clarity)
Compounds of type 8 may exist in two tautomeric forms 8 and 8' (Scheme 3; cf.
[22]). For 8b, the X-ray data show the presence of tautomer 8b in the crystalline state.
The existence of the same tautomer in (D6)DMSO solution was evidenced by 1H-NMR
spectroscopy: in the spectrum of 8b in (D6)DMSO, NHappears as a t at 8.99 ppm and
ArCH2 absorbs at 4.64 as a d (J ˆ 5.6 Hz). Similar signals are observed for 8f (t at 8.85
and d at 4.64 ppm). Given that, in 8b, R2 is an electron-withdrawing group, whereas it is
an electron-donating substituent in 8f, and both compounds were detected as tautomer
of type 8, we deduce by analogy that all prepared selenoureas of type 8 exist in the same
tautomeric form.
Dropwise addition of 1.1 equiv. of Et3N to a stirred solution of 8 in dry acetone led
to the formation of an orange-red precipitate. After the addition of ice-water to the
mixture, an additional amount of the precipitate was formed. Filtration and
recrystallization of the solid material from EtOHgave the diselenides 9a d and 9g
in reasonable yields (Scheme 3 and Table 1). Their structures were deduced from the
elemental analyses and the spectroscopic data, and, in the cases of 9a and 9b, they were
established by X-ray crystallography (Fig. 3).

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Helvetica Chimica Acta Vol. 85 (2002)
Fig. 3. ORTEP Plots [46] of the molecular structures of a) 9b and b) 9a (arbitrary numbering of the atoms; 50%
probability ellipsoids; the solvent molecules have been omitted for clarity)
The crystal structure of 9b shows that the molecule is a dimer of the expected 2,4-
diarylimidazole-5-selenol with the coupling occurring via an SeÀSe bond. The
molecule has crystallographic C2 symmetry, and the asymmetric unit contains one half
of this molecule plus one highly disordered DMF molecule. Each half of the molecule
has two planar sections: the nitrophenyl group, and the five-membered ring with its
bromophenyl substituent. These two planes intersect at an angle of 29.28(9)8. The
SeÀSe bridge links the two halves of the molecule to form an overall sandwich or U-
shaped conformation where the two halves of the molecule lie over and approximately
parallel to one another. The nitrophenyl group in one half overlays and is parallel to the
five-membered ring plus its bromophenyl substituent of the other half of the molecule
and vice versa. Each NHgroup of 9b forms an intermolecular H-bond with the amide
O-atom of a neighboring DMF molecule. The overall crystal packing thus forms a
layered structure with DMF molecules interspersed between the layers.

Helvetica Chimica Acta Vol. 85 (2002)
1109
The crystal structure of 9a is similar to that of 9b with the two 2,4-diarylimidazole
moieties being oriented almost antiparallel to one another. The asymmetric unit
contains one molecule of the diselenide plus two molecules of AcOEt. The two NH
groups of 9a form intermolecular H-bonds with the CˆO O-atom of each of the two
AcOEt molecules. Therefore, these interactions link the three symmetry-independent
moieties in the structure into a single trimeric entity.
A reaction mechanism for the formation of the diselenides of type 9 is proposed in
Scheme 4. Deprotonation of the benzylic CH2 group, which is acidified by the NO2
group in the para position, leads to the carbanion 10. Cyclization by nucleophilic attack
at the isoselenocyanate C-atom gives the 2,4-diaryl-4H-imidazole-5-selenolate 11,
which aromatizes to yield 12. The latter undergoes oxidative dimerization to give the
final product 9.
Scheme 4
R2
R2
R2 = NO2
Et3N
N
N
N
C
Se
N
C
Se
R1
R1
10
3
R2
R2
H
O2
N
N
9
Se
Se
N
N
H
R1
R1
12
11
It is worth mentioning that the reaction fails in the absence of the p-NO2 group in
the benzyl moiety (R2=NO2). Obviously, the benzylic CH2 group is not acidic enough
in these cases to be deprotonated by Et3N. Similarly, the electron-donating substituents
R1 ˆ Me and MeO of the −benzamidine× ring also prevent deprotonation. On the other
hand, halogen substituents, as well as a CN group, in the p-position are tolerated.
In conclusion, bis(imidazol-5-yl) diselenides 9 with R1 ˆ NO2 and R2 not being an
electron-donating group are conveniently accessible via the reaction of isoselenocya-

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Helvetica Chimica Acta Vol. 85 (2002)
nates of type 3 with Et3N. The isoselenocyanates 3 are easily obtained from the reaction
of benzimidoyl chlorides 7 and KSeCN. As N-benzylbenzamides 6 are the starting
materials for the preparation of 7, and KSeCN is smoothly prepared from elemental Se
and KCN in EtOH, the described synthesis of diselenides 9 is cheap and safe as no
highly toxic Se compounds are used.
We thank the analytical units of our institute for spectra and analyses. Financial support of this work by the
Swiss National Science Foundation, the Dr. Helmut Legerlotz-Stiftung, and F. Hoffmann-La Roche AG, Basel, is
gratefully acknowledged.
Experimental Part
1. General. See [20].
2. Preparation of N-Benzylbenzamides. General Procedure. To a cooled soln. of the appropriate
benzylamine (0.036 mol) in pyridine (50 ml, ice-bath) was slowly added the corresponding benzoyl chloride
(0.039 mol) under stirring. After 10 min, the ice-bath was removed, and the mixture was stirred for 3 h at r.t. in
the cases of liquid benzoyl chlorides or for 1 h at 908 when the benzoyl chloride was solid. Then, cold H2O
(100 ml) was added, and the mixture was stirred at 08 for 10 min. The residue was filtered and washed several
times with cold H2O. The crude product was recrystallized from EtOH. When recrystallization was not possible,
the crude product was simply washed with hot EtOH.
N-(4-Nitrobenzyl)benzamide (6a). From 6.79 g (36 mmol) of 4-nitrobenzylamine hydrochloride (5a ¥ HCl)
and 5.60 g (39 mmol) of benzoyl chloride (4a): 6.0 g (65%). Yellowish crystals. M.p. 155.0 156.08 (EtOH).
1H-NMR ((D6)acetone): 8.62 (br. s, NH); 8.18, 7.63 (AA'BB', J ˆ 8.8, 4 arom. H); 7.70 7.40 (m, 5 arom. H);
4.73 (d, J ˆ 6.1, ArCH2NH).
4-Bromo-N-(4-nitrobenzyl)benzamide (6b). From 6.79 g (36 mmol) of 5a ¥ HCl and 8.56 g (39 mmol) of 4-
bromobenzoyl chloride (4b): 8.7 g (72%). Yellowish crystals. M.p. 173.0 174.08 (EtOH). 1H-NMR ((D6)ace-
tone): 8.52 (br. s, NH); 8.19 (AA'BB', J ˆ 8.8, 2 arom. H); 7.89 (CC'DD', J ˆ 8.7, 2 arom. H); 7.80 7.60
(m, 4 arom. H); 4.73 (d, J ˆ 6.0, CH2).
4-Chloro-N-(4-nitrobenzyl)benzamide (6c). From 6.79 g (36 mmol) of 5a ¥ HCl and 6.82 g (39 mmol) of 4-
chlorobenzoyl chloride (4c): 7.0 g (67%). Yellowish crystals. M.p. 168.0 168.28 (EtOH). 1H-NMR ((D6)ace-
tone): 8.52 (br. s, NH); 8.19, 7.65 (AA'BB', J ˆ 8.8, 4 arom. H); 7.96, 7.51 (CC'DD', J ˆ 8.7, 4 arom. H); 4.74
(d, J ˆ 6.0, CH2).
4-Fluoro-N-(4-nitrobenzyl)benzamide (6d). From 6.79 g (36 mmol) of 5a ¥ HCl and 6.18 g (39 mmol) of 4-
fluorobenzoyl chloride (4d): 5.4 g (55%). Yellowish crystals. M.p. 171.0 172.08 (EtOH). 1H-NMR ((D6)ace-
tone): 8.50 (br. s, NH); 8.19, 7.64 (AA'BB', J ˆ 8.8, 4 arom. H); 8.20 7.90 (m, 2 arom. H ); 7.30 7.15
(m, 2 arom. H); 4.73 (d, J ˆ 6.0, CH2).
4-Methyl-N-(4-nitrobenzyl)benzamide (6e). From 6.79 g (36 mmol) of 5a ¥ HCl and 6.03 g (39 mmol) of 4-
methylbenzoyl chloride (4e): 8.0 g (82%). Yellowish crystals. M.p. 172.5 173.68 (EtOH). 1H-NMR (CDCl3):
8.17, 7.49 (AA',BB', J ˆ 8.3, 4 arom. H); 7.71, 7.24 (CC'DD', J ˆ 8.1, 4 arom. H); 6.71 (br. s, NH); 4.72 (d, J ˆ 6.1,
CH2); 2.40 (s, Me).
4-Methoxy-N-(4-nitrobenzyl)benzamide (6f). From 6.79 g (36 mmol) of 5a ¥ HCl and 6.65 g (39 mmol) of
4-methoxybenzoyl chloride (4f): 8.0 g (78%). Yellowish crystals. M.p. 161.7 162.48 (EtOH). 1H-NMR
((D6)acetone): 8.30 (br. s, NH); 8.18, 7.63 (AA'BB', J ˆ 6.8, 4 arom. H); 7.93, 6.99 (CC'DD', J ˆ 7.0, 4 arom. H);
4.71 (d, J ˆ 6.1, CH2); 3.85 (s, MeO).
4-Cyano-N-(4-nitrobenzyl)benzamide (6g). From 5.30 g (28 mmol) of 5a ¥ HCl and 5.0 g (30 mmol) of 4-
cyanobenzoyl chloride (4g): 4.73 g (60%). Yellowish crystals. M.p. 197.0 198.08 (EtOH). This product has been
used for the following reaction without characterization.
Methyl 4-[N-(4-Nitrobenzyl)carbonylamino]benzoate (6h). From 4.15 g (22 mmol) 5a ¥ HCl and 5.0 g
(25 mmol) of methyl 4-(chlorocarbonyl)benzoate (4h): 4.3 g (63%). Yellowish crystals. M.p. 168.0 168.58
(EtOH). 1H-NMR (CDCl3): 8.17, 7.49 (AA'BB', J ˆ 8.7, 4 arom. H); 8.08, 7.86 (CC'DD', J ˆ 8.4, 4 arom. H);
6.95 (br. s, NH); 4.73 (d, J ˆ 5.9, CH2); 3.93 (s, MeO).
N-Benzyl-4-nitrobenzamide (6i). From 6.42 g (60 mmol) of benzylamine (5b) and 11.7 g (63 mmol) of 4-
nitrobenzoyl chloride (4i): 12.7 g (83%). Yellowish crystals. M.p. 144.0 145.08 (EtOH). 1H-NMR (CDCl3):
8.22, 7.94 (AA'BB', J ˆ 8.9, 4 arom. H); 7.50 7.15 (m, 5 arom. H); 6.85 (br. s, NH); 4.62 (d, J ˆ 5.7, CH2).

Helvetica Chimica Acta Vol. 85 (2002)
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4-Chloro-N-(4-chlorobenzyl)benzamide (6k). From 5.0 g (36 mmol) of 4-chlorobenzylamine (5c) and
6.83 g (39 mmol) of 4-chlorobenzoyl chloride (4c): 8.4 g (85%). Yellowish crystals. M.p. 172.0 1738 (EtOH).
1H-NMR ((D6)acetone): 8.21 (br. s, NH); 7.93, 7.49 (AA'BB', J ˆ 8.6, 4 arom. H); 7.40 7.20 (m, 4 arom. H);
4.58 (d, J ˆ 6.0, CH2).
4-Cyano-N-(4-chlorobenzyl)benzamide (6l). From 2.56 g (18 mmol) of 5c and 3.0 g (18 mmol) of 4g: 3.91 g
(80%). This product has been used for the following reaction without characterization.
3. Preparation of Benzimidoyl Isoselenocyanates. General Procedure. A mixture of an N-benzylbenzamide
of type 6 and 2 3 equiv. SOCl2 was heated to reflux until the evolution of SO2 ceased (2 3 h). Excess SOCl2
was evaporated, and the corresponding N-benzylbenzimidoyl chloride was dried in vacuo for 24 h. This crude
material was dissolved in dry acetone, and the soln. was added slowly to a freshly prepared soln. of 1.1 equiv. of
KSeCN in dry acetone under stirring. After stirring the mixture at r.t. for 30 min, it was poured onto ice/H2O,
and the product was filtered by suction and air-dried. The crude product was recrystallized from CH2Cl2/
hexane6).
Similar to N-phenylbenzimidoyl isoselenocyanates of type 2 [10], these products are relatively stable in
solid state at r.t. but decompose slowly in CDCl3 and other organic solvents.
N-(4-Nitrobenzyl)benzimidoyl Isoselenocyanate (3a). From 5.38 g (21 mmol) of 6a: 3.7 g (51.2%).
Yellowish crystals. M.p. 87.0 88.08 (CH2Cl2/hexane)7). IR: 3076w, 3027w, 2921w, 2872w, 2057s, 2017s, 1613s,
1603s, 1577m, 1520s, 1490m, 1448m, 1386w, 1339s, 1309m, 1298m, 1267s, 1206m, 1171m, 1157w, 1109m, 1079m,
1027s. 1H-NMR (CDCl3): 8.22 (AA'BB', J ˆ 8.8, 2 arom. H); 8.15 7.55 (m, 7 arom. H); 4.98 (s, CH2). 13C-NMR
(CDCl3): 147.1, 145.8, 141.5 (3s, 3 arom. C); 138.6 (s, NCSe); 132.4 (s, CN2); 132.1, 128.7, 128.3, 127.6, 123.7 (5d,
‡
9 arom. C); 55.5 (t, CH2). CI-MS (NH3): 348 (16), 347 (14), 346 (100, [M ‡ 1] ), 345 (7), 344 (47), 343 (16), 342
(16), 298 (5), 266 (24), 256 (9), 241 (5), 239 (8). Anal. calc. for C15H11N3O2Se (344.23): C 52.34, H3.22, N 12.21;
found: C 52.63, H3.39, N 12.15.
4-Bromo-N-(4-nitrobenzyl)benzimidoyl Isoselenocyanate (3b). From 8.37 g (25 mmol) of 6b: 5.0 g
(47.3%). Yellowish crystals. M.p. 117.0 117.58 (CH2Cl2/hexane). IR: 3082w, 2849w, 2031s, 1623s, 1597s, 1585s,
1567m, 1511s, 1482s, 1397s, 1346s, 1289m, 1259s, 1195m, 1137s, 1110m, 1069s, 1008s. 1H-NMR (CDCl3): 8.23, 7.60
(AA'BB', J ˆ 8.7, 4 arom. H); 7.85, 7.60 (CC'DD', J ˆ 8.7, 4 arom. H); 4.96 (s, CH2). 13C-NMR (CDCl3): 147.3,
145.7, 140.9, 131.5, 127.1 (4s, 4 arom. C, CN2); 139.5 (s, NCSe); 132.1, 129.1, 128.4, 123.9 (4d, 8 arom. C); 55.7
(t, CH2). Anal. calc. for C15H10BrN3O2Se (423.12): C 42.58, H2.38, N 9.93; found: C 42.57, H2.55, N 9.98.
Crystals suitable for X-ray crystal-structure determination were grown from CH2Cl2/hexane.
4-Chloro-N-(4-nitrobenzyl)benzimidoyl Isoselenocyanate (3c). From 6.7 g (23 mmol) of 6c: 3.3 g (37.8%).
Yellowish crystals. M.p. 106.3 107.68 (CH2Cl2/hexane). IR: 3107w, 3080w, 3059w, 2924w, 2849w, 2076s, 2022s,
1620s, 1599s, 1593s, 1570m, 1510s, 1487s, 1401m, 1353s, 1291m, 1225m, 1196w, 1173m, 1111m, 1089s, 1071s, 1012s,
1001m. 1H-NMR (CDCl3): 8.23, 7.60 (AA'BB', J ˆ 8.7, 4 arom. H); 7.93, 7.44 (CC',DD', J ˆ 8.6, 4 arom. H); 4.98
(s, CH2). 13C-NMR (CDCl3): 147.2, 145.6, 138.5, 130.9 (4s, 4 arom. C); 140.6, 138.8 (2s, NCSe, CN2); 129.0, 128.9,
128.3, 123.7 (4d, 8 arom. C); 55.6 (t, CH2). Anal. calc. for C15H10ClN3O2Se (378.67): C 47.58, H2.66, N 11.10,
found: C 47.42, H2.92, N 11.10.
4-Fluoro-N-(4-nitrobenzyl)benzimidoyl Isoselenocyanate (3d). From 6.16 g (22.5 mmol) of 6d: 6.0 g
(73.7%). Yellowish crystals. M.p. 98.0 99.08 (CH2Cl2/hexane). IR: 3108w, 3081w, 3046w, 2849w, 2069s, 2012s,
1625s, 1600s, 1505s, 1410m, 1400m, 1347s, 1320m, 1292s, 1265s, 1231s, 1197m, 1154s, 1111m, 1101m, 1068s, 1010m.
1H-NMR (CDCl3): 8.23, 7.60 (AA'BB', J ˆ 8.7, 4 arom. H); 8.10 7.90, 7.30 7.15 (2m, 4 arom. H); 4.97 (s, CH2).
13C-NMR (CDCl3): 165.2 (d, 1J(C,F) ˆ 254, 1 arom. C); 147.3, 145.8, 128.8 (3s, 3 arom. C); 140.5, 139.2 (2s,
NCSe, CN2); 129.8 (dd, 3J(C,F) ˆ 9, 2 arom. C); 128.3, 123.8 (2d, 4 arom. C); 115.9 (dd, 2J(C,F) ˆ 22,
2 arom. C); 55.6 (t, CH2). Anal. calc. for C15H10FN3O2Se (362.22): C 49.74, H2.78, N 11.60; found: C 49.74,
H3.05, N 11.54.
6
)
To avoid decomposition during recrystallization, the product was dissolved in CH2Cl2 at r.t., and then
hexane was added. The soln. was concentrated i.v. (448) and then cooled on ice. Within 1 h, yellow crystals
were formed. A red oil (decomposed material) remained on the bottom of the flask. In some cases, the red
oil was formed on the bottom of the flask as a separate layer before crystallization and was separated from
the homogeneous yellow-reddish soln. To avoid decomposition, the temp. during the recrystallization
should be kept as low as possible, and the product should be kept in the soln. as shortly as possible.
In an analogous experiment, almost pure 3a was obtained without recrystallization in 99.5% yield (m.p.
85.5 86.58).
7
)

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Helvetica Chimica Acta Vol. 85 (2002)
4-Methyl-N-(4-nitrobenzyl)benzimidoyl Isoselenocyanate (3e). From 7.0 g (26 mmol) of 6e: 4.0 g (43.1%).
Yellowish crystals. M.p. 94.6 95.68 (CH2Cl2/hexane). IR: 2928w, 2840w, 2075s, 2036s, 1666w, 1620s, 1600s,
1570m, 1520s, 1510s, 1491m, 1403m, 1394m, 1379w, 1341s, 1290m, 1256m, 1196w, 1184m, 1122w, 1108m, 1066m,
1015w. 1H-NMR (CDCl3): 8.22, 7.60 (AA'BB', J ˆ 8.8, 4 arom. H); 7.87, 7.26 (CC'DD', J ˆ 8.3, 4 arom. H); 4.96
(s, CH2); 2.42 (s, Me). 13C-NMR (CDCl3): 147.2, 146.1, 142.9, 129.9 (4s, 4 arom. C, CN2); 138.3 (s, NCSe); 129.5,
128.4, 127.7, 123.8 (4d, 8 arom. C); 55.6 (t, CH2); 21.5 (q, Me). Anal. calc. for C16H13N3O2Se (358.25): C 53.64,
H3.66, N 11.73; found: C 53.68, H3.61, N 11.66.
4-Methoxy-N-(4-nitrobenzyl)benzimidoyl Isoselenocyanate (3f). From 7.4 g (26 mmol) of 6f: 1.7 g (17.6%).
Yellowish crystals. M.p. 93.1 93.38 (CH2Cl2/hexane). IR: 3108w, 3079w, 3002w, 2971w, 2849w, 1999s, 1731w,
1628s, 1606s, 1576s, 1523s, 1509s, 1465m, 1421m, 1342s, 1317m, 1297m, 1253s, 1169s, 1110m, 1057s, 1029s.
1H-NMR (CDCl3): 8.22, 7.59 (AA'BB', J ˆ 8.7, 4 arom. H); 7.93, 6.96 (CC'DD', J ˆ 8.9, 4 arom. H); 4.95
(s, CH2); 3.87 (s, MeO). 13C-NMR (CDCl3): 162.9, 147.2, 146.3, 141.2 (4s, 4 arom. C); 138.5 (s, NCSe); 125.1
(s, CN2); 129.5, 128.4, 123.8, 114.2 (4d, 8 arom. C); 55.6 (q, MeO); 55.5 (t, CH2). Anal. calc. for C16H13N3O3Se
(374.25): C 51.35, H3.50, N 11.23; found: C 51.84, H3.73, N 11.16.
4-Cyano-N-(4-nitrobenzyl)benzimidoyl Isoselenocyanate (3g). From 4.2 g (15 mmol) of 6g: 3.23 g
(58.6%). Yellowish crystals. M.p. 130.0 131.08 (CH2Cl2/hexane). 1H-NMR (CDCl3): 8.24, 7.61 (AA'BB', J ˆ
8.8, 4 arom. H); 8.12, 7.77 (CC'DD', J ˆ 8.6, 4 arom. H); 5.03 (s, CH2). 13C-NMR: 147.4, 145.3, 140.3, 136.5 (4s,
3 arom. C, CN2); 138.8 (s, NCSe); 132.4, 128.3, 128.1, 123.8 (4d, 8 arom. C); 117.9 (s, CN); 115.6 (s, arom. CCN);
55.8 (t, CH2).
Methyl 4-{(Isoselenocyanato)[(4-nitrobenzyl)imino]methyl}benzoate (3h). From 3.77 g (12 mmol) of 6h:
1.63 g (33.8%). Yellowish crystals. M.p. 119.0 120.08 (CH2Cl2/hexane). 1H-NMR (CDCl3): 8.24, 7.62
(AA'BB', J ˆ 8.8, 4 arom. H); 8.13, 8.05 (CC'DD', J ˆ 8.7, 4 arom. H); 5.01 (s, CH2); 3.95 (s, MeO). 13C-NMR:
166.1 (s, COOMe); 147.3, 145.6, 136.3, 133.3 (4s, 4 arom. C); 140.9, 138.7 (2s, CN2, NCSe); 129.9, 128.4, 127.7,
123.9 (4d, 8 arom. C); 55.9 (t, CH2); 52.5 (q, MeO).
N-Benzyl-4-nitrobenzimidoyl Isoselenocyanate (3i). From 11.52 g (45 mmol) of 6i: 4.37 g (28.2%).
Yellowish crystals. M.p. 74.0 75.08 (CH2Cl2/hexane). IR: 3104w, 3073m, 2894w, 2858w, 1994s, 1522s, 1493m,
1454m, 1408m, 1346s, 1267s, 1105w, 1083m, 1072s, 1028m, 1011m. 1H-NMR (CDCl3): 8.29, 8.15 (AA'BB', J ˆ 8.1,
4 arom. H); 7.51 7.28 (m, 5 arom. H); 4.95 (s, CH2). 13C-NMR (CDCl3): 149.7, 138.4, 137.6 (3s, 3 arom. C);
140.8, 138.7 (2s, NCSe, CN2); 128.8, 128.7, 127.9, 127.5, 123.8 (5d, 9 arom. C); 57.2 (t, CH2). Anal. calc. for
C15H11N3O2Se (344.23): C 52.34, H3.22, N 12.21; found: C 52.30, H3.48, N 12.10.
4-Chloro-N-(4-chlorobenzyl)benzimidoyl Isoselenocyanate (3k). From 7.56 g (27 mmol) of 6k: 4.6 g
(46.3%). Yellowish crystals. M.p. 74.0 75.08 (CH2Cl2/hexane). IR: 3037w, 2926w, 2854w, 2074s, 2038s, 1617s,
1590s, 1568s, 1489s, 1399s, 1346m, 1294m, 1277m, 1252s, 1223m, 1196m, 1176m, 1109w, 1089s, 1071s, 1013s. 1H-NMR
(CDCl3): 7.89, 7.41 (AA'BB', J ˆ 8.6, 4 arom. H); 7.40 7.20 (m, 4 arom. H); 4.84 (s, CH2). 13C-NMR (CDCl3):
138.9 (s, NCSe); 139.8, 138.3, 136.6, 133.1, 131.2 (5s, 4 arom. C, CN2); 129.0, 128.9, 128.8, 128.7 (4d, 8 arom. C);
55.9 (t, CH2). Anal. calc. for C15H10Cl2N2Se (368.12): C 48.94, H2.74, N 7.61; found: C 48.66, H2.99, N 7.40.
N-(4-Chlorobenzyl)-4-cyanobenzimidoyl Isoselenocyanate (3l). From 1.95 g (7.2 mmol) of 6l: 1.1 g
(42.6%). Yellow-brownish crystals. M.p. 111.0 112.08. IR: 3093w, 3076w, 2924w, 2888w, 2852w, 2023s, 1615s,
1574m, 1563m, 1490s, 1402s, 1342m, 1317m, 1304m, 1294s, 1277m, 1254s, 1194m, 1173s, 1113w, 1077s, 1014s.
1H-NMR (CDCl3): 8.08, 7.74 (AA'BB', J ˆ 8.6, 4 arom. H); 7.42 7.25 (m, 4 arom. H); 4.88 (s, CH2). 13C-NMR
(CDCl3): 139.7 (s, NCSe); 136.6, 136.2, 133.3, 129.4 (4s, 3 arom. C, CN2); 132.5, 129.2, 128.9, 128.2 (4d,
8 arom. C); 117.9 (s, CN); 115.4 (s, arom. CCN); 56.2 (t, CH2). Anal. calc. for C16H10ClN3Se (358.68): C 53.58,
H2.81, N 11.72; found: C 53.79, H3.01, N 11.42.
4. Preparation of Selenourea Derivatives. 4.1. General Procedure. To a stirred soln. of isoselenocyanates 3 in
acetone, 1.1 equiv. of morpholine was added at r.t. The color of the mixture changed immediately to dark yellow.
After 15 30 min, 3 was completely consumed according to TLC, and to the mixture was added slowly cold H2O
until a yellow precipitate was formed. The solid was filtered by suction, air-dried, and the crude product was
recrystallized from CH2Cl2/hexane.
N'-[(Morpholin-4-yl)(selenocarbonyl)]-N-(4-nitrobenzyl)benzimidamide (8a). From 0.41 g (1.19 mmol) of
3a: 0.51 mg (99.5%). Yellowish crystals. M.p. 169.0 169.58 (EtOH): 1H-NMR (CDCl3): 8.20 (AA'BB', J ˆ 8.7,
2 arom. H); 7.55 7.39 (m, 7 arom. H); 4.70 (d, J ˆ 5.9, ArCH2N); 4.28 (t-like, J ꢀ 4.4, CH2O); 3.80 3.72
(m, CH2O, CH2N); 3.59 3.57 (m, CH2N). 13C-NMR (CDCl3)8)9): 147.3, 145.0, 133.5 (3s, 3 arom. C); 131.1,
8
)
)
The signal for CSe could not be localized.
The signal for CN2 could not be localized.
9

Helvetica Chimica Acta Vol. 85 (2002)
1113
128.7, 128.0, 127.7, 123.9 (5d, 9 arom. C); 66.6, 66.0 (2t, 2 CH2O); 52.5 51.5, 47.5 46.5 (2 br. t, 2 CH2N); 48.0
‡
(t, ArCH2N). CI-MS (NH3): 433 (6, [M ‡ 1] ), 431 (5), 368 (21), 365 (10), 353 (15), 327 (19), 326 (100), 306
(12), 296 (8), 256 (18). Anal. calc. for C19H20N4O3Se (431.34): C 52.90, H4.64, N 12.99; found: C 52.75, H4.85,
N 12.96.
4-Bromo-N'-[(morpholin-4-yl)(selenocarbonyl)]-N-(4-nitrobenzyl)benzimidamide (8b). From 0.34 g
(0.8 mmol) of 3b: 0.20 g (48.8%). Yellowish crystals. M.p. 158.0 159.08 (CH2Cl2/hexane). IR: 3299w, 3077w,
2916w, 2851w, 1605s, 1587s, 1563m, 1478s, 1425m, 1393m, 1347s, 1322m, 1310m, 1285s, 1240m, 1225m, 1198m,
1
1178m, 1124m, 1109s, 1072m, 1027m, 1007m. H-NMR (CDCl3): 8.21 (AA'BB', J ˆ 8.6, 2 arom. H); 7.60 7.50
(m, 4 arom. H); 7.31 (CC'DD', J ˆ 8.4, 2 arom. H); 4.68 (d, J ˆ 6.0, ArCH2N); 4.28 (t-like, J ꢀ 4.7, CH2O); 3.90
1
3.70 (m, CH2O, CH2N); 3.60 3.58 (m, CH2N). H-NMR (600 MHz, (D6)DMSO)): 8.99 (t, J ˆ 5.6, NH); 8.21,
7.65 (AA'BB', J ˆ 8.5, 4 arom. H); 7.67, 7.35 (CC'DD', J ˆ 8.5, 4 arom. H); 4.64 (d, J ˆ 5.7, ArCH2N); 4.05 (t-like,
J ꢀ 4.4, CH2O); 3.59 (t-like, J ꢀ 4.6, CH2O); 3.52 3.49, 3.49 3.45 (2m, 2 CH2N). 13C-NMR (CDCl3)9): 184.6
(s, CSe); 147.6, 144.7, 142.3, 133.0 (4s, 4 arom. C); 132.2, 129.4, 128.1, 124.1 (4d, 8 arom. C); 66.7, 66.2 (2t,
2 CH2O); 53.0 52.0, 48.0 47.0 (2 br. t, 2 CH2N); 48.3 (t, ArCH2N). Anal. calc. for C19H19BrN4O3Se (510.24):
C 44.72, H3.75, N 10.98; found: C 44.42, H4.05, N 10.89.
Crystals suitable for X-ray crystal-structure determination were grown from benzene.
4-Fluoro-N'-[(morpholin-4-yl)(selenocarbonyl)]-N-(4-nitrobenzyl)benzimidamide (8d). From 0.25 g
(0.69 mmol) of 3d: 0.20 g (64.5%). Yellowish crystals. M.p. 171.0 172.08 (CH2Cl2/hexane). IR: 3408w, 3190s,
3063m, 2903m, 2850m, 1602s, 1585s, 1556s, 1518s, 1504s, 1484s, 1435s, 1346s, 1274s, 1255s, 1224s, 1203s, 1184m,
1154m, 1131m, 1114s, 1064m, 1038m, 1023s. 1H-NMR (CDCl3): 8.20, 7.54 (AA'BB', J ˆ 8.7, 4 arom. H); 7.50
7.35, 7.30 7.03 (2m, 4 arom. H); 4.70 (d, J ˆ 6.0, ArCH2NH); 4.28 (t-like, J ꢀ 4.5, CH2O); 4.10 3.70 (m, CH2O,
CH2N); 3.70 3.50 (m, CH2N). 13C-NMR (CDCl3)9): 184.3 (s, CSe); 164.1 (d, 1J(C,F) ˆ 253, 1 arom. C); 147.4,
144.8 (2s, 3 arom. C); 129.9 (dd, 3J(C,F) ˆ 8.8, 2 arom. C); 128.0, 123.9 (2d, 4 arom. C); 115.9 (dd, 2J(C,F) ˆ 22,
2 arom. C); 66.5, 66.0 (2t, 2 CH2O); 51.8, 48.1, 47.4 (3t, 2 CH2N, ArCH2NH). Anal. calc. for C19H19FN4O3Se
(449.34): C 50.79, H4.26, N 12.47; found: C 50.52, H4.42, N 12.40.
4-Methyl-N'-[(morpholin-4-yl)(selenocarbonyl)]-N-(4-nitrobenzyl)benzimidamide (8e). From 0.29 g
(0.8 mmol) of 3e: 0.27 g (75.0%). Yellowish crystals. M.p. 135.0 136.08 (CH2Cl2/hexane). IR: 3242m, 3074w,
2959m, 2916m, 2850m, 1608s, 1582s, 1549s, 1519s, 1473s, 1430s, 1383m, 1346s, 1321m, 1281s, 1219s, 1203s, 1181m,
1111s, 1063m, 1022s. 1H-NMR (CDCl3): 8.21, 7.54 (AA'BB', J ˆ 8.7, 4 arom. H); 7.34, 7.22 (CC'DD', J ˆ 8.1,
4 arom. H); 4.71 (d, J ˆ 5.9, ArCH2NH); 4.40 4.25 (m, CH2O); 4.00 3.69 (m, CH2O, CH2N); 3.69 3.51
(m, CH2N); 2.38 (s, Me). 13C-NMR (CDCl3)9): 184.3 (s, CSe); 147.5, 145.2, 142.0 (3s, 4 arom. C); 129.6, 128.1,
127.8, 124.0 (4d, 8 arom. C); 66.7, 66.1 (2t, 2 CH2O); 52.0, 48.1, 47.5 (3t, 2 CH2N, ArCH2NH); 21.5 (q, Me). Anal.
calc. for C20H22N4O3Se (445.37): C 53.94, H4.98, N 12.58; found: C 53.84, H4.94, N 12.34.
4-Methoxy-N'-[(morpholin-4-yl)(selenocarbonyl)]-N-(4-nitrobenzyl)benzimidamide (8f). From 0.3 g
(0.8 mmol) of 3f: 0.28 g (75.6%). Yellow-gray crystals. M.p. 164.0 164.58 (CH2Cl2/hexane). IR: 3238m,
3107w, 3073w, 2949m, 2917m, 2850m, 2559w, 2452w, 1604s, 1574s, 1517s, 1472s, 1431s, 1389m, 1347s, 1305s, 1287s,
1255s, 1221s, 1206s, 1178s, 1128s, 1111s, 1065m, 1025s. 1H-NMR (CDCl3): 8.19, 7.54 (AA'BB', J ˆ 8.7, 4 arom. H);
7.41, 6.91 (CC'DD', J ˆ 8.8, 4 arom. H); 4.72 (d, J ˆ 6.0, ArCH2NH); 4.29 (t-like, J ꢀ 4.2, CH2O); 3.83 (s, MeO);
3.85 3.65 (m, CH2O, CH2N); 3.55 3.50 (m, CH2N). 1H-NMR (600 MHz, (D6)DMSO)): 8.85 (t, J ˆ 5.4, NH);
8.21, 7.65 (AA'BB', J ˆ 8.8, 4 arom. H); 7.40, 7.00 (CC'DD', J ˆ 8.8, 4 arom. H); 4.64 (d, J ˆ 5.9, ArCH2N); 4.13
4.02 (m, CH2O); 3.81 (s, MeO); 3.62 3.55 (m, CH2O); 3.50 3.45, 3.45 3.40 (2m, 2 CH2N). 13C-NMR
(CDCl3)9): 184.3 (s, CSe); 162.1, 147.1, 145.3 (3s, 4 arom. C); 129.7, 128.2, 124.0, 114.3 (4d, 8 arom. C); 66.7, 66.2
(2t, 2 CH2O); 55.4 (q, MeO); 51.8, 48.1, 47.5 (3t, 2 CH2N, ArCH2NH). Anal. calc. for C20H22N4O4Se (461.37):
C 52.07, H4.81, N 12.14; found: C 52.24, H5.07, N 11.86.
4-Cyano-N'-[(morpholin-4-yl)(selenocarbonyl)]-N-(4-nitrobenzyl)benzimidamide (8g). From 0.30 g
1
(0.8 mmol) of 3g: 0.19 g (51.4%). Yellowish crystals. M.p. 127.0 127.38 (CH2Cl2/hexane). H-NMR (CDCl3):
8.21, 7.52 (AA'BB', J ˆ 8.7, 4 arom. H); 7.70, 7.52 (CC'DD', J ˆ 8.4, 4 arom. H); 4.65 4.45 (m, ArCH2NH);
4.40 4.25 (m, CH2O); 4.00 3.69 (m, CH2O, CH2N); 3.71 3.53 (m, CH2N). 13C-NMR (CDCl3)9): 184.3
(s, CSe); 147.6, 144.2, 114.6 (3s, 3 arom. C); 132.6, 128.6, 128.1, 124.2 (4d, 8 arom. C); 117.9 (s, CN); 114.6 (s,
arom. CCN); 66.5, 66.0 (2t, 2 CH2O); 53.2, 48.3, 47.1 (3t, 2 CH2N, ArCH2NH).
Methyl 4-{[(Morpholin-4-yl)(selenocarbonyl)amino][(4-nitrobenzyl)amino]methyl}benzoate (8h). From
0.25 g (0.62 mmol) of 3h: 0.27 g (90.0%). Yellowish crystals. M.p. 180.0 181.08 (CH2Cl2/hexane). 1H-NMR
(CDCl3): 8.20, 7.54 (AA'BB', J ˆ 8.8, 4 arom. H); 8.06, 7.50 (CC'DD', J ˆ 8.5, 4 arom. H); 5.30 (s, ArCH2N);
4.70 4.60 (m, CH2O); 3.91 (s, MeO); 3.90 3.75 (m, CH2O, CH2N); 3.60 3.50 (m, CH2N). 13C-NMR
(CDCl3)8)9): 166.1 (s, COOMe); 147.5, 144.8, 139.0, 132.3 (4d, 4 arom. C); 129.9, 128.1, 127.9, 124.1 (4d,
4 arom. C); 66.5, 66.0 (2t, 2 CH2O); 52.3 (q, MeO); 51.8, 48.1, 47.5 (3t, 2 CH2N, ArCH2NH).

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Helvetica Chimica Acta Vol. 85 (2002)
N-Benzyl-N'-[(morpholin-4-yl)(selenocarbonyl)]-4-nitrobenzimidamide (8i). From 0.30 g (0.87 mmol) of
3i: 0.20 g (53.2%). Orange-reddish crystals. M.p. 165.0 166.08 (CH2Cl2/hexane): IR: 3445s, 3053w, 2963m,
2925m, 2896m, 2850m, 1625s, 1591s, 1543s, 1514s, 1495m, 1459s, 1424s, 1384m, 1366m, 1341s, 1310s, 1297s, 1279s,
1238m, 1219s, 1209s, 1111s, 1077m, 1063m, 1017s. 1H-NMR (CDCl3): 8.25, 7.60 (AA'BB', J ˆ 8.8, 4 arom. H);
7.45 7.20 (m, 5 arom. H); 4.70 4.50 (m, ArCH2NH); 4.38 4.25 (m, CH2O); 4.00 3.75 (m, CH2O, CH2N);
3.73 3.59 (m, CH2N). 13C-NMR (CDCl3)8)9): 148.9, 136.8 (2s, 3 arom. C); 129.0, 128.9, 128.0, 127.4, 123.9 (5d,
9 arom. C); 66.7, 66.2 (2t, 2 CH2O); 51.8, 48.3, 47.6 (3t, 2 CH2N, ArCH2N). Anal. calc. for C19H20N4O3Se
(431.35): C 52.90, H4.67, N 12.99; found: C 52.74, H4.89, N 12.92.
4-Chloro-N-(4-chlorobenzyl)-N'-[(morpholin-4-yl)(selenocarbonyl)]benzimidamide (8k). From 0.22 g
(0.59 mmol) of 3k: 0.15 g (55.5%). Yellowish crystals. M.p. 173.0 173.58 (CH2Cl2/hexane). IR: 3383w,
3238m, 3051w, 2990w, 2958m, 2915w, 2852m, 1593s, 1567m, 1529s, 1488s, 1472s, 1426s, 1362m, 1335m, 1309m,
1291s, 1279s, 1237m, 1223s, 1207s, 1178m, 1123m, 1112s, 1093s, 1066m, 1024s, 1011s. 1H-NMR (CDCl3): 7.50 7.15
(m, 8 arom. H); 4.65 4.45 (m, ArCH2NH); 4.35 4.15 (m, CH2O); 3.90 3.65 (m, CH2O, CH2N); 3.65 3.50
(m, CH2N). 13C-NMR (CDCl3)8)9): 137.2, 135.8, 133.6, 132.5 (4s, 4 arom. C); 129.3, 129.0, 128.8 (3d, 8 arom. C);
66.7, 66.1 (2t, 2 CH2O); 51.8, 48.1, 46.9 (3t, 2 CH2N, ArCH2NH). Anal. calc. for C19H19Cl2N3OSe (455.24):
C 50.13, H4.21, N 9.23; found: C 49.96, H4.50, N 9.13.
N-(4-Chlorobenzyl)-4-cyano-N'-[(morpholin-4-yl)(selenocarbonyl)]benzimidamide (8l). From 0.30 g
(0.83 mmol) of 3l: 0.30 g (81.0%). Yellowish crystals. M.p. 161.0 162.08. IR: 3384s, 3044w, 2964w, 2926w,
2899m, 2857m, 2237s, 1632m, 1605s, 1522s, 1491s, 1464s, 1426s, 1357m, 1302s, 1290s, 1275s, 1222s, 1206m, 1112s,
1
1064m, 1019s. H-NMR (CDCl3): 7.69, 7.53 (AA'BB', J ˆ 8.4, 4 arom. H); 7.45 7.18 (m, 4 arom. H); 4.65 4.45
(m, ArCH2NH); 4.38 4.22 (m, CH2O); 3.92 3.69 (m, CH2O, CH2N); 3.71 3.53 (m, CH2N). 13C-NMR
(CDCl3)9): 184.3 (s, CSe); 135.4, 133.9 (2s, 3 arom. C); 132.5, 129.2, 128.8, 128.6 (4d, 8 arom. C); 117.9 (s, CN);
114.5 (s, arom. CCN); 66.7, 66.2 (2t, 2 CH2O); 53.2, 48.3, 47.1 (3t, 2 CH2N, ArCH2NH). Anal. calc. for
C20H19ClN4OSe (445.80): C 53.88, H4.30, N 12.57; found: C 53.64, H4.26, N 12.31.
5. Preparation of Bis(imidazol-5-yl) Diselenides. 5.1. General Procedure. Into a soln. of benzimidoyl
isoselenocyanates 3 in dry acetone, 1.1 equiv. Et3N diluted in acetone was dropped under stirring at r.t. A
transient violet color was observed during the addition of Et3N, and, after 20 min, a precipitate was formed. The
mixture was further stirred for 2 h, then ice/H2O was added slowly until a yellow precipitate was formed10),
which was filtered by suction and recrystallized from EtOH.
Bis[4-(4-nitrophenyl)-2-phenylimidazol-5-yl] Diselenide (9a). From 3.44 g (10 mmol) of 3a: 2.0 g (58.3%).
Orange crystals. M.p. 175.0 178.08 (EtOH)11). IR: 3301m, 3065w, 1597s, 1540w, 1509s, 1483s, 1457m, 1413w,
1368w, 1335s, 1209w, 1180w, 1134w, 1158w, 1109s, 1028w. 1H-NMR ((D7)DMF): 13.25 (s, 2 NH); 8.17
(AA'BB', J ˆ 7.7, 4 arom. H); 8.25 7.40 (m, 14 arom. H). 13C-NMR ((D7)DMF): 150.7, 146.8, 145.7 (3s,
6 arom. C); 140.1, 130.1, 112.4 (3s, 6 C of 2 imidazoles); 129.9, 129.3, 127.9, 126.2, 123.7 (5d, 18 arom. C). Anal.
calc. for C30H20N6O4Se2 (686.44): C 52.49, H2.94, N 12.24; found: C 52.55, H2.94, N 12.07.
Bis[2-(4-bromophenyl)-4-(4-nitrophenyl)imidazol-5-yl] Diselenide (9b). From 3.67 g (8.67 mmol) of 3b:
1.35 g (36.9%). Orange crystals. M.p. 253.0 254.08 (EtOH). IR: 3313m, 1596s, 1506s, 1479s, 1433m, 1379w,
1335s, 1208m, 1182w, 1139w, 1108m, 1069m, 1046w, 1008m. 1H-NMR ((D7)DMF): 13.28 (s, 2 NH); 8.14, 8.00
(AA'BB', J ˆ 8.9, 8 arom. H); 7.92, 7.65 (CC'DD', J ˆ 8.6, 8 arom. H). 13C-NMR ((D7)DMF): 149.0, 146.2, 145.4,
122.9 (4s, 8 arom. C); 140.1, 128.7, 112.4 (3s, 6 C of 2 imidazoles); 131.9, 127.5, 127.3, 123.2 (4d, 16 arom. C).
Anal. calc. for C30H18Br2N6O4 Se2 (844.23): C 42.68, H2.15, N 9.95; found: C 42.55, H2.31, N 9.97.
Crystals suitable for X-ray crystal-structure determination were grown from DMF.
Bis[2-(4-chlorophenyl)-4-(nitrophenyl)imidazol-5-yl] Diselenide (9c). From 2.80 g (7.39 mmol) of (3c):
1.00 g (35.8%). Orange crystals. M.p. 278.3 279.08 (EtOH). IR: 3372s, 3318m, 3068w, 2924w, 2437w, 1690w,
1596s, 1508s, 1481s, 1431s, 1380s, 1331s, 1271m, 1199m, 1133m, 1109m, 1087m, 1014m. 1H-NMR ((D7)DMF):
13.29 (s, 2 NH); 8.14 (AA'BB', J ˆ 8.9, 4 arom. H); 8.03 7.91 (m, 8 arom. H ); 7.51 (CC'DD', J ˆ 8.6,
4 arom. H). 13C-NMR ((D7)DMF): 149.6, 146.8, 145.8, 135.1 (4s, 8 arom. C); 140.7, 128.9, 112.7 (3s, 6 C of 2
imidazoles); 129.5, 127.9, 127.8, 123.7 (4d, 16 arom. C). Anal. calc. for C30H18Cl2N6O4Se2 (755.33): C 47.70,
H2.40, N 11.13, found: C 47.47, H2.67, N 11.08.
Bis[2-(4-fluorophenyl)-4-(4-nitrophenyl)imidazol-5-yl] Diselenide (9d). From 2.54 g (7.0 mmol) of 3d:
0.95 g (37.5%). Orange crystals. M.p. 321.0 322.08 (EtOH). IR: 3369m, 3090w, 2921w, 1595s, 1508s, 1493s,
10
)
)
If too much H2O was added, the formation of an emulsion was observed.
In an analogous experiment, almost pure 9a was obtained without recrystallization in 94.0% yield (m.p.
176 1778).
11

Helvetica Chimica Acta Vol. 85 (2002)
1115
1440w, 1333s, 1270w, 1228m, 1159m, 1132w, 1108m, 1014w. 1H-NMR ((D7)DMF): 13.19 (s, 2 NH); 8.50 8.27
(m, 4 arom. H); 8.27 7.98 (m, 8 arom. H); 7.55 7.30 (m, 4 arom. H). 13C-NMR ((D7)DMF): 164.9 (s, 2 ar-
om. CF)12); 149.0, 146.1, 145.8 (3s, 6 arom. C); 140.0, 126.1, 113.0 (3s, 6 C of 2 imidazoles); 127.9 (dd, 3J(C,F) ˆ
8.5, 4 arom. C); 127.3, 123.1 (2d, 8 arom. C); 115.7 (dd, 2J(C,F) ˆ 22, 4 arom. C). Anal. calc. for
C30H18F2N6O4Se2 (722.42): C 49.88, H2.51, N 11.63; found: C 49.58, H2.85, N 11.56.
Bis[2-(4-cyanophenyl)-4-(4-nitrophenyl)imidazol-5-yl] Diselenide (9g). From 0.68 g (1.84 mmol) of 3g:
0.32 g (47.0%). Yellowish crystals. M.p. 331.0 332.08 (EtOH). 1H-NMR ((D7)DMF): 13.50 (s, 2 NH); 8.13
(AA'BB', J ˆ 8.4, 4 arom. H); 8.00 7.80 (m, 12 arom. H). 13C-NMR ((D7)DMF): 149.6, 146.1, 145.8, 133.0 (4s,
8 arom. C); 140.7, 126.0, 111.7 (3s, 6 C of 2 imidazoles); 132.7, 127.2, 125.9, 123.0 (4d, 16 arom. C); 118.7 (s, CN).
6. X-Ray Crystal-Structure Determination of 3b, 8b, 9b, and 9a (see Table 2 and Figs. 1 3)13). All
measurements were performed at low temp. with graphite-monochromated MoKa radiation (l 0.71073 ä)
Table 2. Crystallographic Data for Compounds 3b, 8b, 9b, and 9a
3b
8b
9b
9a
Crystallized from
Empirical formula
CH2Cl2/hexane
benzene
DMF
AcOEt
C15H10BrN3O2Se C19H19BrN4O3Se C30H18Br2N6O4Se2 C30H20N6O4Se2
¥ 0.5(C6H6)
549.24
pale-brown, prism orange, plate
¥ 2(C3H7NO)
990.30
¥ 2(C4H8O2)
862.53
red-orange, prism
Formula weight [g molÀ1
Crystal color, habit
]
423.07
yellow, prism
Crystal dimensions [mm]
Temp. [K]
Crystal system
Space group
0.15 Â 0.20 Â 0.25 0.10 Â 0.12 Â 0.30 0.10 Â 0.25 Â 0.35 0.30 Â 0.32 Â 0.42
160(1)
160(1)
monoclinic
P21/c
160(1)
monoclinic
C2/c
173(1)
monoclinic
P21/c
triclinic
≈
P1
Z
2
4
4
4
Reflections for cell determination
30577
83610
53372
25
2q Range for cell determination [8]
Unit-cell parameters a [ä]
2
55
4
60
4
60
37 40
14.701(3)
19.378(4)
15.012(4)
90
117.54(1)
90
3792(1)
1.511
5.0146(1)
8.6157(2)
18.4948(5)
79.676(1)
87.109(1)
78.978(1)
771.51(3)
1.821
5.5560(1)
13.9170(2)
28.6773(3)
90
90.7483(5)
90
2217.22(6)
1.645
3.532
12.2454(2)
18.3502(3)
17.6110(3)
90
101.8708(6)
90
3872.7(1)
1.698
4.034
b [ä]
c [ä]
a [8]
b [8]
g [8]
V [ä3]
Dx [g cmÀ3
]
m(MoKa) [mmÀ1
Scan type
]
5.039
f and w
55
2.009
w/2q
50
w
f and w
60
2q(max) [8]
60
Total reflections measured
Symmetry-independent reflections
Reflections used [I > 2s(I)]
Parameters refined
Final R
15804
3516
2823
200
0.0373
0.0366
51430
6339
4553
46292
5637
4422
7187
6879
3352
495
0.0501
0.0367
0.005
1.494
284
199
0.0524
0.0522
0.01
0.0460
0.0466
0.01
wR
Weights: p in w ˆ [s2(Fo) ‡ (pFo)2]À1 0.008
Goodness-of-fit
1.942
2.232
2.280
Secondary extinction coefficient
Final Dmax/s
7(2) Â 10À7
0.0008
0.001
1.87; À1.10
0.0006
1.30; À1.22
0.002
0.54; À0.59
D1 (max; min) [e äÀ3
]
0.43; À0.45
12
)
)
This is the left part of the d, the right part overlaps with t of (D7)DMF.
13
Crystallographic data (excluding structure factors) for the structures of 3b, 8b, 9b, and 9a have been
deposited with the Cambridge Crystallographic Data Centre as supplementary publications No. CCDC-
173505 173508. Copies of the data can be obtained, free of charge, on application to the CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: ‡44-(0)1223-336033; e-mail: deposit@ccdc.cam.ac.uk).

1116
Helvetica Chimica Acta Vol. 85 (2002)
either on a Nonius KappaCCD diffractometer fitted with an Oxford Cryosystems Cryostream 700 cooler (3b, 8b,
and 9b) or on a Rigaku AFC5R diffractometer mounted on a 12-KW rotating-anode generator (9a). The data
collection and refinement parameters are given in Table 2, and views of the molecules are shown in Figs. 1 3. In
the cases of 3b, 8b, and 9b, data reduction was performed with HKL Denzo and Scalepack [48]. The intensities
were corrected for Lorentz and polarization effects, and a numerical absorption correction [49] was applied in
the cases of 3b, 8b, and 9b, whereas in the case of 9a, an empirical absorption correction based on Y scans was
applied [50]. The structures were solved by direct methods with SIR92 [51], which revealed the positions of all
non-H-atoms. The non-H-atoms were refined anisotropically. The amine H-atoms of 8b and 9a were placed in
the positions indicated by a difference-electron-density map and their positions were allowed to refine together
with isotropic displacement parameters. All other H-atoms in each structure were fixed in geometrically
calculated positions (d(CÀH) ˆ 0.95 ä) and each was assigned a fixed isotropic displacement parameter with a
value equal to 1.2 Ueq of its parent atom. In the case of 8b, the asymmetric unit also contains one half of a
benzene molecule, which sits across a center of inversion. The asymmetric unit of 9b contains one half of the
organoselenium molecule plus one highly disordered DMF molecule. As it was difficult to model the disordered
DMF molecule adequately, the SQUEEZE [52] function of the program PLATON [53] was used to remove the
contribution of the solvent from the reflection intensity data, and the subsequent solvent free model could be
refined successfully. The asymmetric unit of 9a contains one diselenide molecule and two molecules of AcOEt.
Refinement of each structure was carried out on F using full-matrix least-squares procedures, which minimised
the function Sw(j Fo jÀj Fc j )2. A correction for secondary extinction was applied in the case of 3b. Neutral-
atom-scattering factors for non-H-atoms were taken from [54a] and the scattering factors for H-atoms from
[55]. Anomalous dispersion effects were included in Fc [56]; the values for f ' and f '' were those of [54b], and the
values of the mass attenuation coefficients are those of [54c]. All calculations were performed using the teXsan
[57] crystallographic software package.
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Received November 22, 2001