The reaction of 1,2,3-selenadiazole with olefins

Article abstract of DOI:10.1016/S0022-328X(00)00484-8

When 1,2,3-selenadiazoles synthesized from cyclic ketones were treated with an excess amount of olefins at 130°C, the addition of a vinyl radical, which was generated in situ by the denitrogenation of 1,2,3-selenadiazoles, to a carbon-carbon double bond followed by intramolecular cyclization proceeded efficiently giving the corresponding dihydroselenophenenes in moderate to good yields along with the formation of the corresponding 1,4-diselenins and selenophenes as by-products. In this reaction, the number of carbon atoms on the cyclic ring of the ketones used as the starting materials in the synthesis of the 1,2,3-selenadiazoles plays an important role in the selectivity of the products. In contrast to the reaction of the 1,2,3-selenadiazoles prepared from the cyclic ketones, in the reaction of 1,2,3-selenadiazoles derived from aromatic and linear ketones, the dihydroselenophenene and 1,4-diselenins derivatives were not obtained and the corresponding alkynes were formed as the sole product.

Full text of DOI:10.1016/S0022-328X(00)00484-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 611 (2000) 488–493
The reaction of 1,2,3-selenadiazole with olefins
Yutaka Nishiyama *1, Yasunobu Hada, Kuniko Iwase, Noboru Sonoda *2
Department of Applied Chemistry, Faculty of Engineering and High Technology Research Center, Kansai Uni6ersity, Suita,
Osaka 564-8680, Japan
Received 1 March 2000; accepted 14 April 2000
Abstract
When 1,2,3-selenadiazoles synthesized from cyclic ketones were treated with an excess amount of olefins at 130°C, the addition
of a vinyl radical, which was generated in situ by the denitrogenation of 1,2,3-selenadiazoles, to a carbon–carbon double bond
followed by intramolecular cyclization proceeded efficiently giving the corresponding dihydroselenophenenes in moderate to good
yields along with the formation of the corresponding 1,4-diselenins and selenophenes as by-products. In this reaction, the number
of carbon atoms on the cyclic ring of the ketones used as the starting materials in the synthesis of the 1,2,3-selenadiazoles plays
an important role in the selectivity of the products. In contrast to the reaction of the 1,2,3-selenadiazoles prepared from the cyclic
ketones, in the reaction of 1,2,3-selenadiazoles derived from aromatic and linear ketones, the dihydroselenophenene and
1,4-diselenins derivatives were not obtained and the corresponding alkynes were formed as the sole product. © 2000 Published by
Elsevier Science S.A. All rights reserved.
Keywords: 1,2,3-Selenadiazole; Olefins; Thermolysis; Dihydroselenophene
1. Introduction
Recently, the synthesis of heterocyclic compounds
containing selenium and the utilization of these com-
pounds in organic synthesis have been steadily increas-
ing [1]. Among selenium-containing heterocyclic
compounds, the 1,2,3-selenadiazoles 1 were of interest
as versatile intermediates for the preparation of alky-
nes, because 1 is easily decomposed with the loss of a
nitrogen molecule and selenium atom under light irradi-
ation and thermal conditions [2,3]. Ando and Tokitoh
et al. have examined the reaction of the sterically
protected bicyclic 1,2,3-selenadiazoles 2–3 with various
organic compounds during light irradiation (u\365
nm and u=265 nm) and assumed the formation of
zwitterionic 4 and biradical 5 intermediates [4].
In contrast to the well known reactivity of 1,2,3-sele-
nadiazole under photolysis conditions [5], the reactivity
of the intermediate of 1,2,3-selenadiazoles under ther-
mal conditions has not yet been elucidated [6]. We
examined the reaction of various 1,2,3-selenadiazoles
with olefins in order to elucidate the characteristic
features of the intermediates generated in situ by the
thermal decomposition of the 1,2,3-selenadiazoles.
These results are reported in this paper.
2. Results and discussion
To clarify the characteristic features of the intermedi-
ates generated in situ by the decomposition of the
1,2,3-selenadiazoles under thermal conditions, 1,2,3-se-
1 *Corresponding author. Tel.: +81-6-6368-1121; fax: +81-6-
6339-4026; e-mail: nishiya@ipcku.kansai-u.ac.jp
2 *Corresponding author.
0022-328X/00/$ - see front matter © 2000 Published by Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00484-8

Y. Nishiyama et al. / Journal of Organometallic Chemistry 611 (2000) 488–493
489
Table 2
lenadiazole (1a) derived from cyclohexanone was first
Reaction of 1a with various olefins
treated with ethyl acrylate 6a under various reaction
conditions and these results are shown in Table 1.
When the reaction was carried out in the presence of an
excess amount of 6a (200 equivalents) at 130°C, the
denitrogenation of 1a followed by addition to the un-
saturated carbon–carbon double bond of 6a and subse-
quent cyclization proceeded to give 7a in 82% yield
along with the formation of 1,4-diselenin 8a (11%) and
selenophenene 9a (6%) (entry 5) [7]. The decrease in the
amounts of 6a led to a decrease in the selectivity of 7a
(entries 1–5). The conversion of 1a and the yield of 7a
were affected by the reaction temperature (entries 5–9).
When the reaction was carried out at a higher reaction
temperature (150°C), 7a was also formed in 83% yield
(entry 8). However, at 180°C, the yield of 7a was
slightly decreased due to the preparation of complex
byproducts (entry 9). On the other hand, in the reaction
at 80°C, the reaction was significantly decreased to
afford 7a in 17% yield along with the recovery of 1a
(77%) (entry 6).
Table 2 shows the results of the treatment of 1,2,3-se-
lenadiazole 1a synthesized from cyclohexanone with
various olefins. When 1a was allowed to react with
methyl acrylate 6b and acrylonitrile 6c, in which elec-
tron withdrawing groups were substituted on the car-
bon–carbon double bond, the corresponding
dihydroselenophenes were formed in 76 and 74% yields,
respectively (entries 1 and 2). In the case of methyl
vinyl ketone, the yield of the addition product was
significantly decreased due to the preparation of com-
plex byproducts (entry 3). For this reaction, the alkyl
substituted on the carbon–carbon double bond has a
significant influence on the selectivity between dihy-
droselenophene 7 and 1,4-dihydroselenin 8a. Ethyl
methacrylate 6e also gave the corresponding dihydrose-
lenophene 7e in 63% yield. In contrast to the reaction
of 6e, when methyl crotonate 6f, in which the methyl
group was substituted at the b-position, was treated
with 1a under the same reaction condition as that of 6e,
the addition reaction of the vinyl radical species gener-
ated in situ with 6f was reduced and 7f was formed in
23% yield with the formation of 58% yield of 8a. In the
case of butyl vinyl ether 6g or 1-octene 6h, 8a was also
formed as the main product.
Table 1
Reaction of 1,2,3-selenadiazole with ethyl acrylate under various
reaction conditions
Next, various 1,2,3-selenadiazols derived from cyclic
ketones were treated with an excess amount of methyl
acrylate (6a) (200 equivalents) at 130°C for 15 h, the
results are shown in Table 3. In the case of the 1,2,3-se-
lenadiazoles prepared from the 2- and 4-methylcyclo-
hexanones, the methyl substituent had no influence on
the reactivity for producing the corresponding dihy-
droselenophenes (entries 4 and 5). On the other hand,
the yield of 7 and the selectivity of 7 and 8 were
influenced by the number of carbon atoms in the cyclic
ketones used for the synthesis of the 1,2,3-selanadia-
zoles (entries 1–3). In the reaction of the 1,2,3-selenadi-
azoles prepared from 4-heptanone and acetophenone,
dihydroselenophene and 1,4-dihydroselenine were not

490
Y. Nishiyama et al. / Journal of Organometallic Chemistry 611 (2000) 488–493
Table 3
quent intramolecular cyclization pathway. In fact, when
1a was treated in the absence of an olefin at 150°C for
15 h, 1.4-diselenine was formed in 82% yield (Eq. 1).
The reaction of various 1,2,3-selenadiazoles with COOEt
(1)
On the other hand, in the case of the 1,2,3-selenadia-
zoles derived from linear and aromatic ketones, dihy-
droselenophenen 7, 1,4-diselenide 8 and selenophene 9
were not formed and the corresponding alkynes as the
sole product were formed in good yields. Therefore, the
reaction of the 1,2,3-selenadiazole derived from linear
and aromatic ketones appears to contain another reac-
tion pathway via the retro [2+3] addition reaction
(path 2) or the concerted elimination of moleculer
nitrogen and selenium atom from the radical intermedi-
ate 10 (path 3).
The striking differences observed between the reac-
tion of the 1,2,3-selenadiazoles (1) derived from cyclic
ketones and the reaction of 1 derived from the linear
ketones appears to be explained in terms of the differ-
ence in these geometries. In the case of 1 derived from
the cyclic ketones, the formation of an alkyne via the
retro [2+3] reaction (path 2) or concerted elimination
(path 3) path was suppressed due to the difficulty in the
formation of the transition states 12 and 13 due to the
cyclic ring, therefore, the homolytic cleavage of N–Se
of 1 and subsequent elimination of the nitrogen
molecule predominantly proceeded to generate the vinyl
radical 11.
In summary, we examined the reaction of 1,2,3-sele-
nadiazoles with an excess amount of olefins at 130°C.
In the case of the 1,2,3-selenadiazole derived from
cyclic ketones, the addition of a vinyl radical, which
was generated in situ by the denitrogenation of the
1,2,3-selenadiazoles, to a carbon–carbon double bond
followed by intramolecular cyclization proceeded effi-
ciently giving the corresponding dihydroselenophenenes
in moderate to good yields. In contrast to the reaction
of the 1,2,3-selenadiazoles prepared from cyclic ke-
tones, in the reaction of the 1,2,3-selenadiazoles derived
from aromatic and linear ketones, the corresponding
alkynes were formed as the sole product.
formed, but the corresponding alkyne was predomi-
nantly formed (Scheme 1).
We cannot explain the decomposition reaction path-
ways of the 1,2,3-selenadiazoles under thermal condi-
tions in detail, however, possible reaction pathways are
shown in Scheme 2. In the case of the 1,2,3-selnadia-
zoles derived from cyclic ketones, the results of the
reaction of 1 with olefins would suggest a reaction
pathway that involved the generation of a vinyl radical
11 (path 1). In the presence of olefins, the vinyl radical
10, which was generated via the homolytic cleavage of
the N–Se bond of 1 and the subsequent denitrogena-
tion, was added to the carbon–carbon double bond
and subsequently cyclized giving the corresponding di-
hydroselenophenen 7. The formation of 8 was also
explained by the attack of the vinyl radical 11 on the
selenium atom of another molecule of the 1,2,3-selena-
diazole following by dinitrogenation and the subse-
Scheme 1.

Y. Nishiyama et al. / Journal of Organometallic Chemistry 611 (2000) 488–493
491
Scheme 2. Plausible reaction pathways.
3. Experimental
7a: 1H-NMR (CDCl3) l 1.26 (t, J=7.3 Hz, 3H),
1.61–1.72 (m, 4H), 1.96–2.22 (m, 4H), 2.72–2.82 (m,
1H), 3.10–3.18 (m, 1H), 4.17 (q, J=7.3 Hz, 1H), 4.18
(q, J=7.3 Hz, 1H), 4.41 (dd, J=5.9, 9.5 Hz, 1H);
13C-NMR (CDCl3) l 14.2, 22.2, 23.5, 27.3, 27.7, 38.3,
43.1, 61.4, 125.2, 131.4, 174.0; IR (neat) 857, 1045,
1096, 1155, 1181, 1207, 1261, 1298, 1324, 1367, 1442,
1H (400 MHz) and 13C (99.5 MHz) NMR spectra
were recorded on a JEOL JNM-GSX-400 spectrometer.
1
The H and 13C chemical shifts are referenced to exter-
nal Me4Si in CDCl3 as the solvent. FT-IR spectra were
obtained using a Perkin–Elmer model Paragon 1000
spectrophotometer. Mass spectra were measured on a
Shimadzu model Qp-5050A. Gas chromatography
(GC) was carried out on Shimadzu GC-14A equipped
with a flame ionizing detector using a capillary column
(Hicap-CBP-1-S25-0.25, 0.25 mm×25 m). Column
chromatography was performed using a 5742 (Aldrich).
Selenium dioxide, semicarbazide hydrochloride and
acetic acid were commercially available high grade
products and were used without purification. 1,2,3-Sele-
nadiazoles were prepared by the reaction of selenium
dioxide with semicarbazone [8]. The other reagents and
solvents were purified by the usual methods before use.
1733, 2834, 2931, 2979 cm−1
.
1
8a: H-NMR (CDCl3) l 1.69–1.74 (m, 8H), 2.45–
2.48 (m, 8H); 13C-NMR (CDCl3) l 23.7, 34.0, 129.7; IR
(neat) 553, 762, 816, 846, 940, 1070, 1110, 1133, 1170,
1263, 1321, 1431, 1560, 2827, 2857, 2922 cm−1
.
1
9a: H-NMR (CDCl3) l 1.75–1.84 (m, 8H), 2.17–
2.37 (m, 8H), 2.76–2.77 (m, 4H); 13C-NMR (CDCl3) l
22.7, 24.2, 25.7, 27.6, 136.5, 137.3; IR (neat) 795, 1005,
1105, 1132, 1237, 1289, 1333, 1441, 1525, 2835, 2852,
2926 cm−1
.
1
7b: H-NMR (CDCl3) l 1.63–1.80 (m, 4H), 1.96–
2.22 (m, 4H), 2.76–2.84 (m, 1H), 3.10–3.15 (m, 1H),
3.72 (s, 3H), 4.42 (dd, J=5.9, 9.5 Hz, 1H); 13C-NMR
(CDCl3) l 22.2, 23.5, 27.3, 27.7, 38.0, 43.2, 52.6, 125.3,
131.4, 174.5; IR (neat) 844, 983, 1055, 1155, 1172, 1209,
3.1. General procedure for the reaction of 1,2,3-selena-
diazole with olefins
1262, 1293, 1329, 1435, 1737, 2835, 2855, 2930 cm−1
.
1
7c: H-NMR (CDCl3) l 1.61–1.79 (m, 4H), 1.98–
2.32 (m, 4H), 2.91–3.07 (m, 2H), 4.24 (dd, J=5.5, 8.8
Hz, 1H); 13C-NMR (CDCl3) l 21.0, 22.0, 23.4, 27.4,
27.6, 46.0, 121.6, 127.6, 129.8; IR (neat) 822, 997, 1062,
1156, 1200, 1262, 1307, 1350, 1437, 1655, 2231, 2834,
In a 50 ml stainless steel autoclave were placed
1,2,3-selenadiazole (0.5 mmol), and olefins (100 mmol).
The autoclave was heated by a mantle heater and
maintained at 130°C with magnetic stirring for 13 h.
The remaining olefin was removed under reduced pres-
sure and purified by column chromatography on silica
gel (C6H14:CHCl3=10:1 as the eluate) to give dihy-
droselenophene, 1,4-diselenin and selenophenene. The
structures of the products were assigned based on the
1H, 13C-NMR, IR amd GC mass spectra.
2855, 2928 cm−1
.
1
7d: H-NMR (CDCl3) l 1.61–1.73 (m, 4H), 1.95–
2.23 (m, 4H), 2.26 (s, 3H), 2.64–2.75 (m, 1H), 3.05–
3.11 (m, 1H), 4.40 (dd, J=3.7, 9.2 Hz, 1H); 13C-NMR
(CDCl3) l 22.2, 23.6, 27.2, 27.4, 27.8, 41.5, 47.6, 124.7,

492
Y. Nishiyama et al. / Journal of Organometallic Chemistry 611 (2000) 488–493
132.3, 203.9; IR (neat) 827, 994, 1062, 1168, 1201, 1239,
1206, 1326, 1367, 1445, 1462, 1731, 2849, 2922, 2978
cm−1
1263, 1317, 1353, 1438, 1705, 2833, 2855, 2928 cm−1
.
.
1
7e: H-NMR (CDCl3) l 1.62–1.72 (m, 4H), 1.82 (s,
3H), 1.98–2.09 (m, 4H), 2.11–2.22 (m, 2H), 2.41–2.46
(m, 1H), 3.35–3.41 (m, 1H), 3.73 (s, 3H); 13C-NMR
(CDCl3) l 22.3, 23.6, 27.5, 28.0, 28.2, 51.6, 52.3, 52.8,
125.8, 130.5, 175.9; IR (neat) 720, 767, 822, 995, 1063,
1097, 1136, 1154, 1211, 1239, 1260, 1274, 1307, 1349,
7l (mixture of stereoisomers): 1H-NMR (CDCl3) l
1.03 (d, J=7.2 Hz, 1.76 H), 1.08 (d, J=7.2 Hz, 1.24
H),1.25 (t, J=7.2 Hz, 3H), 1.25–1.40 (m, 1H), 1.58–
1.67 (m, 1H), 1.72–1.82 (m, 2H), 2.13–2.17 (m, 2H),
2.18–2.34 (m, 1H), 2.64–2.75 (m, 0.5 H), 2.92–3.12 (m,
1H), 3.24–3.35 (m, 0.5H), 4.15–4.21 (m, 2H), 4.37 (dd,
J=3.2, 7.2 Hz, 0.58H), 4.40 (dd, J=3.2, 7.2 Hz,
0.42H); 13C-NMR (CDCl3) l 14.3, 19.9, 20.0, 21.4,
21.6, 27.7, 30.7, 30.8, 32.9, 33,0. 38.1, 38.5, 41.2, 41.3,
61.5, 125.7, 125.8, 135.8, 135.9, 174.1; IR (neat)
1373, 1436, 1732, 2856, 2928 cm−1
.
1
7f (mixture of stereoisomers): H-NMR (CDCl3) l
1.12 (d, J=7.0 Hz, 2.7H), 1.45 (d, J=7.0 Hz, 0.3H),
1.54–1.74 (m, 4H), 1.95–2.25 (m, 4H), 2.98–3.06 (m,
0.1H), 3.20–3.28 (m, 0.9H), 3.72 (s, 0.3H), 3.73 (s,
2.7H), 3.97 (d, J=5.5 Hz, 0.9H), 4.58 (d, J=7.7 Hz,
0.1H); 13C-NMR (CDCl3) l 17.7, 22.2, 22.3, 23.5, 23.6,
26.7, 27.5, 46.5, 49.5, 52.6, 124.4, 135.5, 174.2; IR
(neat) 735, 780, 811, 911, 1019, 1064, 1145, 1175, 1199,
1180,1209, 1318, 1322, 1732, 2852, 2927, 2957 cm−1
.
1
7m (mixture of stereoisomers): H-NMR (CDCl3) l
0.97 (t, J=7.2 Hz, 1.5H), 0.98 (t, J=7.2 Hz, 1.5H),
1.26 (t, J=7.2 Hz, 3H), 1.24–1.30 (m, 1H), 1.70–1.87
(m, 3H), 1.98–2.15 (m, 2H), 2.18–2.23 (m, 1H), 2.72–
2.88 (m, 1H), 3.04–3.18 (m, 1H), 1.61–1.73 (m, 4H),
4.12–4.21 (m, 2H), 4.43 (dt, J=4.0, 7.2 Hz, 1H);
13C-NMR (CDCl3) l 14.2, 21.4, 21.5, 27.5, 27.6, 29.9,
30.0, 30.5, 30.6, 35.4, 35.5, 38.6, 38.7, 42.7, 42.8, 61.4,
61.5, 124.9, 125.0, 131.1, 131.2, 174.0, 174.1; IR (neat)
1153, 1179, 1204, 1324, 1368, 1733, 2832, 2850, 2921,
1272, 1341, 1434, 1736, 2835, 2929 cm−1
.
7g: 1H-NMR (CDCl3) l 0.91 (t, J=7.3 Hz, 3H),
1.30–1.43 (m, 2H), 1.52–1.78 (m, 6H), 1.99–2.36 (m,
4H), 2.79–2.83 (m, 1H), 3.00–3.04 (m, 1H), 3.27 (dt,
J=6.6, 9.2 Hz, 1H), 3.58 (dt, J=6.6, 9.2 Hz, 1H), 5.72
(dd, J=1.5, 6.6 Hz, 1H); 13C-NMR (CDCl3) l 14.0,
19.6, 22.4, 23.8, 27.7, 28.2, 31.3, 50.2, 70.0, 86.4, 125.5,
130.2; IR (neat) 717, 827, 904, 1010, 1045, 1079, 1115,
1150, 1209, 1262, 1301, 1328, 1378, 1438, 1654, 1735,
2951 cm−1
.
2871, 2929 cm−1
.
Acknowledgements
7h: 1H-NMR (CDCl3) l 0.88 (t, J=7.0 Hz, 3H),
1.20–1.40 (m, 10H), 1.47–1.69 (m, 4H), 1.98–2.03 (m,
2H), 2.18–2.22 (m, 2H), 2.39–2.43 (m, 1H), 2.78–2.80
(m, 1H), 3.88–3.90 (m, 1H); 13C-NMR (CDCl3) l 14.3,
22.6, 22.8, 23.9, 28.0, 28.2, 29.2, 29.9, 32.0, 38.2, 45.2,
48.6, 126.4, 131.7; IR (neat) 724, 998, 1165, 1261, 1376,
This research was supported in part by Grant in Aid
for Scientific Research on Priority Area (No. 10133253,
The Chemistry of Interelement Linkage, 10450347 and
10555317) from the Ministry of Education, Science,
Culture and Sports, Goverment of Japan.
1457, 1541, 1654, 1734, 2854, 2925 cm−1
.
7i: 1H-NMR (CDCl3) l 1.27 (t, J=7.0 Hz, 3H),
2.19–2.34 (m, 4H), 2.35–2.45 (m, 4H), 2.62–2.67 (m,
1H), 2.95–3.01 (m, 1H), 4.18 (q, J=7.0 Hz, 1H), 4.19
(q, J=7.0 Hz, 1H), 4.91 (dd, J=5.9, 9.5 Hz, 1H);
13C-NMR (CDCl3) l 14.2, 28.0, 31.0, 31.7, 34.4, 46.8,
61.5, 132.0, 142.6, 173.7; IR (neat) 857, 1046, 1193,
References
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1325, 1368, 1444, 1733, 2847, 2955 cm−1
.
7j: 1H-NMR (CDCl3) l 1.26 (t, J=7.3 Hz, 3H),
1.48–1.77 (m, 6H), 2.08–2.30 (m, 4H), 2.99 (dd, J=
9.5, 16.5 Hz, 1H), 3.28 (dd, J=5.9, 16.5 Hz, 1H), 4.17
(q, J=7.3 Hz, 1H), 4.18 (q, J=7.3 Hz, 1H), 4.37 (dd,
J=5.9, 9.5 Hz, 1H); 13C-NMR (CDCl3) l 14.2, 26.6,
27.0, 30.5, 30.9, 31.0, 39.0, 46.8, 61.4, 127.9, 135.2,
173.9; IR (neat) 755, 858, 969, 1023, 1097, 1178, 1207,
1325, 1367, 1444, 1732, 2848, 2920, 2978 cm−1
.
7k: 1H-NMR (CDCl3) l 1.27 (t, J=7.1 Hz, 3H),
1.35–1.59 (m, 3H), 2.11–2.38 (m, 4H), 2.92 (dd, J=
9.5, 16.1 Hz, 1H), 3.20 (dd, J=4.8, 16.1 Hz, 1H), 4.17
(q, J=7.1 Hz, 1H), 4.18 (q, J=7.1 Hz, 1H), 4.34 (dd,
J=4.8, 9.5 Hz, 1H); 13C-NMR (CDCl3) l 14.3, 25.9,
26.4, 28.2, 28.6, 28.7, 29.2, 38.3, 43.6, 61.4, 127.7, 133.7,
174.2; IR (neat) 688, 736, 859, 1040, 1068, 1096, 1179,
[3] (a) H. Meier, I. Menzel, J. Chem. Soc. Chem. Commun. (1971)
1059. (b) H. Meier, N. Hanold, H. Kolshorn, Angew. Chem. Int.

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