Reaction of ketone hydrazones with diselenium dihalides: Simple synthesis of Δ3-1,3,4-selenadiazolines and 2,5-diarylselenophenes

Article abstract of DOI:10.1246/bcsj.78.1121

Sterically congested cis- and trans-Δ³-1,3,4- selenadiazolines were isolated by one-pot reactions of ketone hydrazones with diselenium dibromide, which suggested the in situ formation of selone and diazoalkane intermediates. The thermolysis of these compounds gave symmetrical olefins, whereas oxidation afforded the corresponding azines. The reaction of acetophenone hydrazones with diselenium dibromide afforded 2,5- diarylselenophenes in moderate yields. The reaction proceeded through selone intermediates.

Full text of DOI:10.1246/bcsj.78.1121

Ó 2005 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 78, 1121–1126 (2005) 1121
Reaction of Ketone Hydrazones with Diselenium Dihalides: Simple
Synthesis of ꢀ3-1,3,4-Selenadiazolines and 2,5-Diarylselenophenes
ꢀ;1;2
Kentaro Okuma,
Toshiharu Izaki,1 Kento Kubo,1 Kosei Shioji,1 and Yoshinobu Yokomori3
1Department of Chemistry, Faculty of Science, Fukuoka University, Jonan-ku, Fukuoka 814-0180
2Advanced Materials Institute, Fukuoka University, Jonan-ku, Fukuoka 814-0180
3Department of Chemistry, National Defense Academy, Hashirimizu, Yokosuka 239-8686
Received November 5, 2004; E-mail: kokuma@fukuoka-u.ac.jp
Sterically congested cis- and trans-ꢀ3-1,3,4-selenadiazolines were isolated by one-pot reactions of ketone hydra-
zones with diselenium dibromide, which suggested the in situ formation of selone and diazoalkane intermediates. The
thermolysis of these compounds gave symmetrical olefins, whereas oxidation afforded the corresponding azines. The
reaction of acetophenone hydrazones with diselenium dibromide afforded 2,5-diarylselenophenes in moderate yields.
The reaction proceeded through selone intermediates.
Sterically congested ꢀ3-1,3,4-selenadiazolines 1 and ꢀ3-
N
N
1,3,4-thiadiazolines are interesting compounds for their syn-
thetic application of sterically crowded olefins.1 It has been re-
ported that the reactions of sterically hindered selones 2 with
sterically hindered diazoalkanes 3 afford 1, which are decom-
posed to the corresponding symmetrical olefins via thermal
twofold extrusion.1,2 2,5-Diarylselenophenes 4 are synthesized
by reacting 1,3-diynes with hydrogen selenide3 and arylacety-
lenes with 1,2,3-selenadiazoles,4 by the high-temperature
reaction of acetophenone anil with elemental selenium,5 and
by treating titanocycle with selenium diselenocyanate6
(Scheme 1).
However, there has been no report on the synthesis of 4
from ketone hydrazones 5. Recently, we reported in a commu-
nication the synthesis of ꢀ3-1,3,4-selenadiazolines 1 by react-
ing ketone hydrazones 5 with diselenium dibromide.7 We re-
port herein on the full details concerning the reaction of 5 with
diselenium dibromide and the synthesis of 4.
R
R
C
C
Ar
R'
Se
Ar
R'
Se
1
4
Scheme 1.
N N
N
NH2
Se
1a
CH2Cl2
-20°C
5a
+ Se2Br2
+ Et3N
+
+
Se
O
2a
6a
Scheme 2.
Treatment of 5a with diselenium dibromide at ꢁ20 ꢂC resulted
in the formation of dispiro[1,1,3,3-tetramethylindane-2-20-
(ꢀ3-10,30,40-selenadiazoline)-50,200-(100,100,300,300-tetramethylin-
dane)] (1a) (53%) along with 1,1,3,3-tetramethylindane-2-
selone (2a) (10%), and 1,1,3,3-tetramethylindan-2-one (6a)
(5%) (Scheme 2). When the reaction was carried out at rt, se-
lone 2a was obtained in 55% yield. Thus, temperature plays
an important role in the formation of 1a (Table 1).
Results and Discussion
Synthesis and Reaction of 1,3,4-Selenadiazolines. ꢀ3-
1,3,4-Selenadiazolines 1 have been synthesized by reacting se-
lenoketones with diazoalkanes.2 Selenoketones 2, however, are
generally unstable and difficult to isolate.1 Barton and co-
workers suggested the formation of 1 as an intermediate in
the synthesis of sterically crowded alkenes by the reaction of
benzophenone phosphoranylidene hydrazone with elemental
selenium.2 Okazaki et al. also suggested the formation of di-
azoalkane intermediates from the reaction of ketone hydra-
zones 5 with diselenium dichloride. They also reported on
the one-pot synthesis of ꢀ3-1,3,4-telluradiazoline by the reac-
tion of ketone hydrazones with tellurium dichloride.8 If the re-
action of ketone hydrazones with diselenium dihalide gives not
only selones 2, but also diazoalkanes 3, ꢀ3-1,3,4-selenadiazo-
line 1 will be formed in a one-pot operation. To confirm this
possibility, we first attempted the reaction of 1,1,3,3-tetrameth-
ylindan-2-one hydrazones (5a) with diselenium dibromide.
The structure of 1a was confirmed by NMR and X-ray crys-
tallographic analyses (Fig. 1, Table 2).9 In contrast to the struc-
ture of other five-membered heterocyclic compounds, such as
1,2,4-trithiolanes,10 the selenadiazoline ring in 1a is planar and
approximately perpendicular to the indane rings. This structure
is similar to that of 1,3,4-telluradiazoline.11
ꢂ
At ꢁ20 C, the yield of 1a was improved, whereas selone
2a was obtained in moderate yield at elevated temperature.
Actually, two groups have reported on the synthesis of sterical-
ly crowded selones by reacting ketone hydrazones with disele-
nium dihalides at elevated temperature. Guziec and Moustakis
Published on the web June 6, 2005; DOI 10.1246/bcsj.78.1121

1122 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Reaction of Ketone Hydrazones with Diselenium Dibromide
Table 1. Reaction of 5a with Diselenium Dibromide
N
N
C
C
Conditions
Products (Yield/%)
C
N
Se
Temp/ꢂC
Time/h
1a
2a
6a
Recovered 5a
NH2
R
R
ꢁ78
ꢁ40
ꢁ30
ꢁ20
0
5
3
2
2
2
1
1
10
26
34
53
3
8
10
11
10
55
55
72
1
1
2
5
7
9
5
75
50
25
0
0
0
cis-1b R=OPh
cis-1c R=Me
cis-1d R=OMe
cis-1e R=H
R
5b R=OPh
5c R=Me
5d R=OMe
5e R=H
0-5 °C
R
CH2Cl2
+
N
N
C
C
rt
reflux
5
0
Se
0
+ Se2Br2/Et3N
trans-1b R=OPh
trans-1c R=Me
trans-1d R=OMe
trans-1e R=H
R
C
O
+
6b R=OPh
6c R=Me
6d R=OMe
6e R=H
R
Scheme 3.
Fig. 1. X-ray crystallographic structure of 1a.
Table 2. Selected Distances and Angles of 1a
Table 3. Reaction of Pivalophenone Hydrazones 5b–5e
with Diselenium Dibromide
ꢁ
Bond length (A)
Se–C1
N1–N1
N1–C1
1.972(3)
1.234(4)
1.488(3)
Products (Yield/%)
Hydrazone 5 Temp/ꢂC
cis-1 trans-1
6
5b
5b
5c
5d
5e
0
rt
0
0
0
1b
1b trace
7
77
52
58
60
56
6b
6b 15
6c 15
6d 10
5
Bond angle (ꢂ)
C1–Se–C1
N1–N1–C1
N1–C1–Se1
88.4(1)
120.6(1)
105.2(2)
1c
1d
1e
5
2
trace
6e
18
synthesized 2a by reacting 5a with diselenium dibromide in
the presence of triethylamine at 50 ꢂC.12 Okazaki et al. report-
ed the synthesis of 2a by reacting diselenium dichloride with
the Grignard reagent of 5a in refluxing benzene.13
N
N
Et3N
Se Br
N
+
2
2
Se
1f 43%
CH2Cl2
We next attempted the reaction of pivalophenone hydra-
zones with diselenium dibromide. Treatment of p-phenoxypi-
valophenone hydrazone (5b) with diselenium dibromide in the
presence of triethylamine at 0 ꢂC resulted in the formation
of cis-2,5-di-t-butyl-2,5-di-p-phenoxyphenyl-ꢀ3-1,3,4-selena-
diazoline (cis-1b), trans-2,5-di-t-butyl-2,5-di-p-phenoxyphen-
yl-ꢀ3-1,3,4-selenadiazoline (trans-1b), and p-phenoxypivalo-
phenone (6b) (Scheme 3). The structures of cis-1b and
NH2
5f
Scheme 4.
R
− N2
[O]
6
1
Se
N2
R'
2
8
1
N
R
trans-1b were confirmed from their H NMR spectra and ele-
R
Se2Br2
Et3N
N
N
mental analyses. The chemical shift of the tert-butyl group
of trans-1b (0.89 ppm) is higher than that of cis-1b (1.19
ppm), whereas the chemical shifts of the aromatic group of
trans-1b (6.91 and 7.01 ppm) are lower than those of cis-1b
(6.57 and 6.80 ppm). These observations suggest that the aro-
matic plane of cis-1b is on the other side of the aromatic plane,
whereas the tert-butyl group of trans-1b is on the aromatic
plane. Other reactions were carried out in a similar manner
(Table 3).
The reaction of 2,2,5,5-tetramethylcyclopentanone hydra-
zone (5f) with diselenium dibromide in the presence of tri-
ethylamine also afforded dispiro[2,2,5,5-tetramethylcyclo-
pentane-1,20-(ꢀ3-10,30,40-selenadiazoline)-500,100-(200,200,500,500-
tetramethylcyclopentane)] (1f) in 43% yield (Scheme 4).
The postulated mechanism for this reaction is depicted in
R'
Se Se
R'
NH2
5
7
R
− Se
R'
Scheme 5.
Scheme 5. The anion of 5 reacts with diselenium dibromide
to afford 1,2,3,4-diselenadiazoline 7. The extrusion of seleni-
um from 7 affords diazoalkane 3 (minor route), whereas N2
is extruded to afford the selone 2 (major route). Selenadiazo-
line 1 is formed by the 1,3-dipolar cycloaddition reaction of
2 with 3, both generated in situ, as shown in Scheme 5. The
proposed mechanism is similar to that of 1,2,4-telluradiazoline
suggested by Okazaki and co-workers.11

K. Okuma et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1123
1d
5a
m-CPBA
Se
N
N
+
0°C
N
N
C
N N
- SeO
C
C
C
Se
1g
Se
Et3N, CH2Cl2
2g
O
O
O
O
O
+ 1a + 2a + 2g + 6a
Me
12
Me
Me
Me
Se2Br2
+
Scheme 6.
Me
O
C
N
N
C
C
C
C
C
Se
O
9a
O
Ph
O
Me
O
Ph
O
Ph
cis-11
Ph
cis-8
Scheme 8.
C
C
C
1b
Ar
Se
Se
Ar
Ar
CH3
Ar
Ar
C NNH2
O
+
O
Ph
C
C
10
Ph
CH3
H3C
Ph
O
13a Ar=C6H5
13b Ar=p-Tol
13c Ar=p-BrC6H4
4a Ar=C6H5
4b Ar=p-Tol
4c Ar=p-BrC6H4 14c Ar=p-BrC H
O Ph
Et3N
14a Ar=C6H5
14b Ar=p-Tol
C
C
C
6
4
Se
O
O
Ar
Ph
Ph
+ Se2Br2
trans-11
trans-8
CH3
Ar
+
N
C
N
C
H3C
Scheme 7.
9b Ar=C6H5
9c Ar=p-Tol
9d Ar=p-BrC6H4
Actually, when the reaction of 5a with diselenium dibro-
mide was carried out in the presence of 1,3,3-trimethylnorbor-
nane-2-selone (2g), unsymmetrical 1,3,4-selenadiazoline 1g
was obtained in 7% yield along with symmetrical selenadiazo-
line 1a (25%) and indane-2-selone 2a (15%), suggesting that
the intermediates of this reaction are diazoalkane 3 and selone
2 (Scheme 6).
Since cis- and trans-1,3,4-selenadiazolines 1b–1e were iso-
lated, we attempted the thermolysis of 1b to confirm the reac-
tion mechanism of the twofold extrusion. Heating trans-1b up
to 170 ꢂC resulted in the formation of cis-olefin (cis-8, 7%) and
trans-olefin (trans-8, 70%), whereas the thermolysis of cis-1b
gave cis-8 (33%) and trans-8 (66%). These results suggested
that the reaction might proceed through biradical intermedi-
ates. Heating of 1b resulted in the extrusion of nitrogen to af-
ford biradical 10, which recombined to give episelenide 11.
Episelenide 11 is too unstable to isolate, affording cis-8 and
trans-8. The biradical intermediate 10 equilibrates to a more
stable conformer, resulting in the formation of both isomers
(Scheme 7).
Scheme 9.
enolizable ketone hydrazones with diselenium dibromide is the
next topic of interest. Treatment of acetophenone hydrazone
(13a) with diselenium dibromide in refluxing benzene resulted
in the formation of 2,5-diphenylselenophene (4a) in 58% yield
along with 2,3-diphenyl-2-butene (E- and Z-14a) (Scheme 9).
When the reaction was carried out at 20 C, acetophenone
azine (9b) was isolated in 13% yield along with 4a and 13a.
The other reactions are shown in Table 4.
The formation of alkene 14a can be explained by the
thermal twofold extrusion of unstable 1,3,4-selenadiazoline.2
Then, how can we account for the formation of selenophene
4? The initially formed 1-phenylethaneselone (2) partially iso-
merizes to eneselenol, which is easily oxidized to the corre-
sponding diselenide 15. A 3,3-sigmatropic rearrangement re-
sulted in the formation of diselone 16, which again isomerized
to another type of eneselenol 17. Hydrogen selenide abstrac-
tion of 17 finally gave selenophene 4 (Scheme 10).
To confirm the formation of 15, we then performed the re-
action of 2-methyl-1-phenylpropan-1-one (isobutyrophenone)
hydrazone (13d) with diselenium dibromide. When the reac-
tion was carried out in refluxing benzene, the corresponding
alkenyl diselenide 15 was obtained in 42% yield along with
a mixture of E- and Z-2,5-dimethyl-3,4-diphenyl-3-hexene
(14d) (Scheme 11).
ꢂ
An alternative route that includes the initial extrusion of se-
lenium is excluded by the following result. The oxidation of
trans-1d with m-CPBA at room temperature resulted in the
formation of p-methoxypivalophenone azine 9a (50%) and
p-methoxypivalophenone hydrazone 5d (30%), suggesting that
the initial fission of the carbon–selenium bond of selenoxide
affords biradical 12, which easily isomerizes to azine 9a
(Scheme 8).
Synthesis of 2,5-Diarylselenophenes. Because eneselenol
is more stable than the corresponding selone,14 the reaction of
Although the detailed reaction mechanism remains to be
clarified, this is the first example of the formation of 2,5-di-

1124 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Reaction of Ketone Hydrazones with Diselenium Dibromide
Table 4. Reaction of Acetophenone Hydrazones 13 with Diselenium Dibromide
Hydrazone
Ar
Products (Yields/%)
Solvent
Temp/ꢂC
13
4
14
9
13a
13a
13a
13a
13a
13b
13c
C6H5
C6H5
C6H5
C6H5
C6H5
p-Tol
p-BrC6H4
Dichloromethane
Benzene
Benzene
Benzene
THF
ꢁ20
20
60
reflux
reflux
reflux
reflux
4a
4a
4a
4a
4a
4b
4c
25
34
45
58
51
48
39
14a
14a
14a
14a
14a
14b
14c
33
33
33
33
30
20
25
9b
9b
9b
9b
9b
9c
9d
20
20
20
20
15
15
20
Benzene
Benzene
Ph
Ar
Ar
Ar
SeH
CH2
Se Se Ar
H3C
H3C
Ph
C
C
Se
Se Se
CH3
C
CH3
H3C
C
NNH2
2
15
C
Ph
CH
H3C
SeH
SeH
Se
Se
Ar
13d
CH3
-H2Se
[3,3]sigmatropic
Ar
15
Et3N
benzene
4
Ar
Ar
Ph
Ph
+ Se2Br2
16
17
C
C
CH3
+
H3C
CH
CH3
14d
CH
Scheme 10.
CH3
arylselenophene 4 from acetophenone hydrazone 13.
In summary, we synthesized 1,3,4-selenadiazoline 1 by re-
acting ketone hydrazone 5 with diselenium dibromide. When
acetophenone hydrazones were used as substrates, 2,5-diaryl-
selenophenes were obtained in moderate yields.
Scheme 11.
Reaction of p-Phenoxypivalophenone Hydrazone 5b with
Diselenium Dibromide. To a solution of p-phenoxypivalophe-
none hydrazone 5b (0.536 g, 2.0 mmol) and triethylamine (0.88
g, 8.0 mmol) in dichloromethane (20 mL) was added a solution
of diseleniumꢂdibromide (0.80 g, 2.2 mmol) in dichloromethane
(10 mL) at 0 C. After stirring for 3 h, the reaction mixture was
poured into water, separated, and extracted from dichloromethane.
The combined extract was dried over magnesium sulfate, filtered,
and evaporated to give a brown solid, which was chromatograph-
ed over silica gel by elution with hexane–dichloromethane (1:1).
A mixture of cis- and trans-2,5-di-t-butyl-2,5-bis(p-phenoxyphen-
yl)-ꢀ3-1,3,4-selenadiazoline (1b) was obtained first. Pivalophe-
none 6b was obtained second (0.025 g, 0.02 mmol). The mixture
was subjected to gel HPLC to give pure trans-1b (0.45 g, 0.77
mmol) and cis-1b (0.041 g, 0.070 mmol). cis-1b: mp 118–119
Experimental
General. All chemicals were obtained from commercial sup-
pliers and were used without further purification. Analytical TLC
was carried out on precoated plates (Merck silica gel 60, F254)
and flash column chromatography was performed with silica
(Merck, 70–230 mesh). NMR spectra (1H at 400 MHz; 13C at
100 MHz) were recorded in CDCl3 solvent, and the chemical
shifts were expressed in ppm relative to internal TMS. The melt-
ing points were uncorrected.
Material. Ketone hydrazones 5a–f were prepared by the re-
action of ketones with hydrazine monohydrate.2a,b,12 Acetophe-
none hydrazones 13a–d were synthesized by a method from the
literature.15 Selone 2g was synthesized by a method from the lit-
erature.2b
Reaction of 1,1,3,3-Tetramethylindan-2-one Hydrazone 5a
with Diselenium Dibromide. To a solution of indan-2-one hy-
drazone 5a (0.40 g, 2.0 mmol) and triethylamine (0.61 g, 6.0
mmol) in dichloromethane (15 mL) was added dropwise a solution
of diselenium dibromide (0.80 g, 2.2 mmol) in dichloromethane
(10 mL) at ꢁ20 ꢂC. After stirring for 3 h, the reaction mixture
was poured into water, separated, and extracted from dichloro-
methane (10 mL ꢃ 2). The combined extract was dried over mag-
nesium sulfate, filtered, and evaporated to give a brown solid,
which was chromatographed over silica gel by elution with hex-
ane–dichloromethane (1:1). Dispiro[1,1,3,3-tetramethylindane-2-
20-(ꢀ3-10,30,40-selenadiazoline)-50,200-(100,100,300,300-tetramethylin-
dane)] (1a) was eluted first (0.24 g, 0.53 mmol). 1a: mp 170–171
ꢂC (lit.16 mp 170 ꢂC). 1,1,3,3-Tetramethylindane-2-selone (2a)
(0.050 g, 0.20 mmol): mp 39–42 ꢂC (lit.17 mp 40–43 ꢂC), and
1,1,3,3-tetramethylindan-2-one (6a) (0.019 g, 0.10 mmol) were
obtained.
ꢂC. H NMR (CDCl3) ꢀ 1.19 (s, 18H, tert-Bu), 6.57 (d, 4H, J ¼
1
9 Hz, Ar), 6.80 (d, 4H, J ¼ 9 Hz, Ar), 7.05 (m, 2H, Ph), 7.13
(m, 4H, Ph), 7.32 (m, 4H, Ph). 13C NMR (CDCl3) ꢀ 28.31
(t-Bu), 40.38 (q-C), 116.63, 118.40, 121.31 (spiro-C), 122.89,
129.45, 129.57, 135.67, 155.35, 157.01 (Ar). Found: C, 70.36;
H, 6.21; N, 5.11%. Calcd for C34H36N2O2Se: C, 69.97; H, 6.22;
N, 4.80%. trans-1b: mp 162–163 ꢂC. 1H NMR (CDCl3) ꢀ 0.89
(s, 18H, tert-Bu), 6.91 (d, 4H, J ¼ 8:0 Hz, Ar), 7.01 (d, 4H, J ¼
8:0 Hz, Ar), 7.11 (m, 2H, Ph), 7.34 (m, 4H, Ph), 7.52 (m, 4H, Ph).
13C NMR (CDCl3) ꢀ 27.64 (t-Bu), 41.62 (q-C), 116.94, 118.91,
123.26, 126.52 (spiro-C), 129.52, 129.56, 137.52, 156.05,
156.68 (Ar). Found: C, 69.93; H, 6.03; N, 4.44%. Calcd for
C34H36N2O2Se: C, 69.97; H, 6.22; N, 4.80%.
Other reactions were carried out in a similar manner. cis-1c: mp
ꢂ
1
104–105 C. H NMR (CDCl3) ꢀ 1.16 (s, 18H, tert-Bu), 2.09 (s,
6H, Me), 6.66 (d, 4H, J ¼ 8:4 Hz, Ar), 7.00 (d, 4H, J ¼ 8:4
Hz, Ar). 13C NMR (CDCl3); ꢀ 20.64 (Me), 28.26 (t-Bu), 40.37 (q-
C), 121.86, 126.77 (spiro-C), 127.95, 135.89, 137.84 (Ar). Found:
C, 67.09; H, 7.93; N, 6.61%. Calcd for C24H32N2Se: C, 67.43; H,

K. Okuma et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1125
7.55; N, 6.55%. trans-1c: mp 181–182 ꢂC. 1H NMR (CDCl3) ꢀ
0.86 (s, 18H, tert-Bu), 2.33 (s, 6H, Me), 7.06 (d, 4H, J ¼ 8:0
Hz, Ar), 7.43 (d, 4H, J ¼ 8:0 Hz, Ar). 13C NMR (CDCl3) ꢀ
21.13 (Me), 27.34 (tert-Bu), 41.45 (q-C), 126.53 (spiro-C),
127.51, 128.15, 136.51, 139.81 (Ar). Found: C, 67.38; H, 7.55;
N, 6.81%. Calcd for C24H32N2Se: C, 67.43; H, 7.55; N, 6.55%.
cis-1d: mp 102–104 ꢂC. 1H NMR (CDCl3) ꢀ 1.15 (s, 18H, t-
Bu), 3.81 (s, 6H, OMe), 6.41 (d, 4H, J ¼ 8:0 Hz, Ar), 7.06 (d,
4H, J ¼ 8:0 Hz, Ar). Found: C, 62.45; H, 7.03; N, 6.19%. Calcd
for C24H32N2O2Se: C, 62.74; H, 7.02; N, 6.10%. trans-1d: mp
124–125 ꢂC. 1H NMR (CDCl3) ꢀ 0.86 (s, 18H, t-Bu), 3.81 (s,
6H, OMe), 6.80 (d, 4H, J ¼ 8:8 Hz, Ar), 7.48 (d, 4H, J ¼ 8:8
Hz, Ar). 13C NMR (CDCl3) ꢀ 27.49 (t-Bu), 41.49 (q-C), 55.10
(OMe), 112.24, 126.58 (spiro-C), 129.44, 135.17, 158.45 (Ar).
Found: C, 62.95; H, 6.86; N, 6.21%. Calcd for C24H32N2O2Se:
8:0 Hz, Ar), 7.04 (d, 4H, J ¼ 8:0 Hz, OPh), 7.09 (t, 2H, J ¼
7:6 Hz, OPh), 7.12 (d, 4H, J ¼ 8:0 Hz, Ar), 7.34 (t, 4H, J ¼
7:6 Hz, OPh). Found: C, 85.48; H, 7.64%. Calcd for C34H36O2:
C, 85.67; H, 7.61%.
Oxidation of ꢀ3-1,3,4-Selenadiazoline 1d. To a solution of
trans-1,3,4-ꢀ3-selenadiazoline 1d (59 mg, 0.1 mmol) in chloro-
form (5 mL) was added a solution of m-chloroperbenzoic acid
(85%, 61 mg, 0.3 mmol) in chloroform (5 mL) at rt. After being
stirred for 2 h, the reaction mixture was filtered and evaporated
to give dark yellow solid, which was chromatographed over silica
gel by elution with hexane–dichloromethane to afford yellow
crystals of azine 9a (20 mg, 0.05 mmol) and p-methoxypivalo-
phenone (11 mg, 0.056 mmol). 9a: mp 124–125 ꢂC. 1H NMR
(CDCl3) ꢀ 0.92 (s, 18H, t-Bu), 3.82 (s, 6H, OMe), 6.87 (d, 4H,
J ¼ 8:8 Hz, Ar), 6.92 (d, 4H, J ¼ 8:8 Hz, Ar). 13C NMR (CDCl3)
ꢀ 28.18 (t-Bu), 37.93 (q-C), 54.86 (OMe), 112.66, 128.52, 129.04,
158.41 (Ar), 164.74 (C=N). Found: C, 75.77; H, 8.76; N, 7.24%.
Calcd for C22H28N2Se: C, 75.35; H, 8.96; N, 7.32%.
ꢂ
1
C, 62.74; H, 7.02; N, 6.10%. trans-1e: mp 163–164 C. H NMR
(CDCl3) ꢀ 0.87 (s, 18H, t-Bu), 7.25 (m, 6H, Ar), 7.56 (br d, 4H,
J ¼ 7:2 Hz, Ar). 13C NMR (CDCl3) ꢀ 27.50 (t-Bu), 41.39 (q-C),
126.84, 126.99 (spiro-C), 127.18, 128.50, 142.93 (Ph). Found:
C, 66.32; H, 6.99; N, 6.27%. Calcd for C22H28N2Se: C, 66.15;
H, 7.07; N, 7.01%. cis-1e could not be isolated.
Reaction of Acetophenone Hydrazone (13a) with Diseleni-
um Dibromide. To a refluxing solution of acetophenone hydra-
zone 13a (0.27 g, 2.0 mmol) and triethylamine (0.61 g, 6.0 mmol)
in benzene (20 mL) was added dropwise a solution of diselenium
Reaction of 2,2,5,5-tetramethylcyclopentanone hydrazone (5f)
with diselenium dibromide was carried out in a similar manner.
Dispiro[2,2,5,5-tetramethylcyclopentane-1,20-(ꢀ3-10,30,40-selena-
diazoline)-500,100-(200,200,500,500-tetꢂramethylcyclopentane)] (1f): mp
ꢂ
dibromide (0.80 g, 2.2 mmol) in benzene (10 mL) at 0 C. After
refluxing for 2 h, the reaction mixture was poured into water, sep-
arated, and extracted from benzene (10 mL ꢃ 2). The combined
extract was dried over magnesium sulfate, filtered, and evaporated
to give a brown solid, which was chromatographed over silica gel
by elution with hexane–dichloromethane (1:1). A mixture of (E)-
and (Z)-2,3-diphenyl-2-butene (14a) (0.11 g, 0.56 mmol) was
eluted first (E:Z–1:5). The spectral data (1H NMR) of the mixture
of 14a were identical with the reported data.18 2,5-Diphenylsele-
nophene (4a) was eluteꢂd next (0.33 g, 1.16 mmol). 4a: mp 171–
ꢂ
125–126 C (lit.16 mp 126–127 C).
Reaction of 5a with Diselenium Dibromide in the Presence
of Selenofenchone (2g). To a solution of 5a (0.40 g, 2.0 mmol),
(1S)-1,3,3-trimethylbicyclo[2.2.1]heptane-2-selone (2g) (0.43 g,
2.0 mmol), and triethylamine (0.88 g, 8.0 mmol) in dichlorometh-
ane (20 mL) was added a solution of diselenium diꢂbromide (0.80
g, 2.2 mmol) in dichloromethane (10 mL) at ꢁ20 C. After stir-
ring for 2 h, the reaction mixture was poured into water, separated,
and extracted from dichloromethane. The combined extract was
dried over magnesium sulfate, filtered, and evaporated to give
brown solid, which was chromatographed over silica gel by elu-
tion from hexane–dichloromethane (1:1). 1,1,3,3-Tetramethylin-
dane-2-selone (2a) (0.075 g, 0.30 mmol) was obtained first. Sele-
nadiazolines 1a (0.085 g, 0.25 mmol) and 1g (0.029 g, 0.07 mmol)
were eluted second. Compound 1g: yellow crystals, mp 172–174
ꢂC. (lit.17 mp 125–128 ꢂC). 1H NMR (CDCl3) ꢀ 0.93 (s, 3H,
Me), 0.97 (s, 3H, Me), 1.03 (s, 3H, Me), 1.10 (s, 3H, Me), 1.16
(s, 3H, Me), 1.40 (s, 3H, Me), 1.42 (s, 3H, Me), 1.45–1.52 (m,
4H, CH2), 1.80 (br, 1H, CH), 1.99 (br s, 1H, CH), 2.77 (br d,
1H, J ¼ 10:0 Hz, CHH), 7.19–7.25 (m, 4H, Ar). 13C NMR
(CDCl3) ꢀ 18.98 (Me), 23.14 (Me), 25.24 (Me), 26.04 (Me),
29.88 (Me), 33.29 (Me), 33.74 (Me), 36.72, 42.41, 48.05, 49.51,
51.76, 57.14, 122.47, 122.85 (spiro-C), 127.21, 127.26, 128.34,
148.41, 148.78. 1,1,3,3,-Tetramethylindan-2-one (6a) was finally
obtained (0.038 g, 0.20 mmol).
ꢂ
173 C (lit.19 170–172 C). Acetopꢂhenone azine (9b) was finally
ꢂ
eluted. mp 122–123 C. (lit.20 123 C)
Another reaction was carried out in a similar manner. 2,5-di-p-
tolylselenophene (4b). mp 192–194 ꢂC (lit.19 mp 192–194 ꢂC).
1H NMR (400 MHz, CDCl3) ꢀ 2.35 (s, 6H), 7.15 (d, 4H, J ¼
7:6 Hz, Tol), 7.37 (s, 2H), 7.44 (d, 4H, J ¼ 7:6 Hz, Tol). 13C NMR
(100 MHz, CDCl3) ꢀ 21.7 (Me), 125.91, 126.20, 129.86, 133.91,
137.72, 149.65. 2,5-bis(p-bromophenyl)selenophene (4c): mp
ꢂ
ꢂ
1
214–216 C (lit.19 mp 214–216 C). H NMR (400 MHz, CDCl3)
ꢀ 7.39–7.41 (m, 6H), 7.47–7.49 (d, 4H, Ar).
Reaction of 2-Methyl-1-phenylpropan-1-one Hydrazone
(13d) with Diselenium Dibromide. To a refluxing solution of
13d (0.16 g, 1.0 mmol) and triethylamine (0.30 g, 3.0 mmol) in
benzene (15 mL) was added a solution of diselenium dibromide
(0.40 g, 1.1 mmol) in benzene (8 mL). After refluxing for 2 h,
the reaction mixture was poured into water, separated, and extract-
ed from benzene (5 mL ꢃ 2). The combined extract was dried
over magnesium sulfate, filtered, and evaporated to give a brown
solid, which was chromatographed over silica gel by elution from
hexane–dichloromethane (1:1). A mixture of (E)- and (Z)-2,5-di-
methyl-3,4-diphenyl-3-hexene (14d) (0.055 g, 0.21 mmol) was
eluted first (E:Z–3:2). The spectral data (1H NMR) of the mixture
of 14d were identical with the reported data.18 1,2-Bis(2-methyl-
1-phenyl-1-propenyl) diselenide (15) was obtained second. 15:
Yellow oil. 1H NMR (400 MHz, CDCl3) ꢀ 1.56 (s, 6H, Me),
2.00 (s, 6H, Me), 6.79 (d, 4H, J ¼ 7:2 Hz, Ph), 7.09–7.12 (m,
6H, Ph). 13C NMR (100 MHz, CDCl3) ꢀ 23.36 (Me), 25.50
(Me), 126.61, 126.84, 127.67, 130.14, 138.24, 142.37. MS: Found:
422.0. Calcd for C20H22Se2: 422.0 (Mþ). Elemental analysis was
failed due to the small impurity of unseparable 14d.
Thermolysis of ꢀ3-1,3,4-Selenadiazoline 1b. trans-Selena-
diazoline 1b (59 mg, 0.10 mmol) was heated at 180 ꢂC for 10
min. The reaction mixture was dissolved into dichloromethane
and filtered. The solution was evaporated to give cis- and trans-
2,2,5,5-tetramethyl-3,4-bis(p-phenoxyphenyl)-3-hexene (8) (1:3)
in 85% yield. The mixture was subjected to gel-HPLC to afford
ꢂ
1
cis-8 (3.0 mg, 0.007 mmol). mp 108–110 C. H NMR (CDCl3)
ꢀ 1.27 (s, 18H, t-Bu), 6.27 (s, 8H, Ar), 6.76 (d, 4H, J ¼ 7:6 Hz,
OPh), 7.00 (t, 2H, J ¼ 7:6 Hz, OPh), 7.26 (t, 4H, J ¼ 7:6 Hz,
OPh). Found: C, 85.44; H, 7.30%. Calcd for C34H36O2: C,
85.67; H, 7.61%. trans-8 (33 mg, 0.070 mmol): mp 159.5–160.5
ꢂC. 1H NMR (CDCl3) ꢀ 0.75 (s, 18H, t-Bu), 6.95 (d, 4H, J ¼

1126 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Reaction of Ketone Hydrazones with Diselenium Dibromide
l ¼ 2n). A good model was found at first using C2=c space group
by direct method (SIR97) but the model was not so good after
refined. Using C2=c space group, another good model was found
by direct method (SIR97). Attempts to refine the structure in this
space group were successful. Crystal data for 1a: FW ¼ 451:52.
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For reviews, see: C. M. Meyers, ‘‘Comprehensive Organic
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ꢁ
Monoclinic, space group C2=c ¼ 25:9960ð7Þ A, b ¼ 6:1170ð2Þ
ꢂ
ꢂ
ꢁ
ꢁ
A, c ¼ 15:7030ð5Þ A, ꢁ ¼ 90:00 , ꢂ ¼ 114:678ð2Þ , ꢃ ¼
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ꢂ
ꢁ 3
2
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4
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8
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9
The X-ray crystallographic data were collected by a DIP
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Image Plate with Cu Kꢁ radiation. The reflections were collected
at room temperature (293 K). Monoclinic C lattice was deter-
mined from systematic absence of lattice (hkl, h þ k ¼ 2n).
C2=c space group was determined from systematic absence (hol,