Tributylstannyl radical-catalyzed reaction of 1,2,3-selenadiazoles with olefins or dienes

Article abstract of DOI:10.1021/jo010893t

It was found that the reaction of 1,2,3-selenadiazoles derived from cyclic ketones with olefins or dienes was markedly promoted by a catalytic amount of tributylstannyl radical, which was generated in situ from tributylstannyl hydride or allyltributylstannane and AIBN, to give the corresponding dihydroselenophenes in moderate to good yields. In contrast, when 1,2,3-selenadiazoles prepared from linear and aromatic ketones were used as substrates, the same reaction did not take place, and alkynes were formed as the sole product.

Full text of DOI:10.1021/jo010893t

1520
J . Org. Chem. 2002, 67, 1520-1525
Tr ibu tylsta n n yl Ra d ica l-Ca ta lyzed Rea ction of 1,2,3-Selen a d ia zoles
w ith Olefin s or Dien es
Yutaka Nishiyama,* Yasunobu Hada, Masahiro Anjiki, Kazuya Miyake, Sakiko Hanita, and
Noboru Sonoda*
Department of Applied Chemistry, Faculty of Engineering, Kansai University,
Suita, Osaka 564-8680, J apan
nishiya@ipcku.kansai-u.ac.jp
Received September 4, 2001
It was found that the reaction of 1,2,3-selenadiazoles derived from cyclic ketones with olefins or
dienes was markedly promoted by a catalytic amount of tributylstannyl radical, which was generated
in situ from tributylstannyl hydride or allyltributylstannane and AIBN, to give the corresponding
dihydroselenophenes in moderate to good yields. In contrast, when 1,2,3-selenadiazoles prepared
from linear and aromatic ketones were used as substrates, the same reaction did not take place,
and alkynes were formed as the sole product.
In tr od u ction
developed using radical reactions.1 In particular, the
radical-mediated reactions employing a stoichiometric or
an excess amount of tributylstannyl radical, which was
generated in situ from the tributylstannyl hydride/AIBN
or allyltributylstannane/AIBN system, have been widely
utilized in organic synthesis.2
The radical reactions are one of the most popular and
important types of reactions in organic synthesis. Various
transformations such as reduction and inter- and in-
tramolecular carbon-carbon bond formations have been
1,2,3-Selenadiazoles 1 are of recent interest as versatile
intermediates for the preparation of alkynes, because
compounds 1 are easily decomposed with the loss of a
nitrogen molecule and selenium atom under light ir-
radiation and thermal conditions.3-5 Ando and Tokitoh
et al. reported the reaction of sterically protected bicyclic
1,2,3-selenadiazoles 2 and 3 with various organic com-
pounds during light irradiation (hν > 365 and > 265 nm)
and assumed the formation of biradical (4) and zwitter-
ionic (5) intermediates.6 We have recently examined the
* To whom correspondence should be addressed.
(1) For examples, see: (a) Giece, B. Radical in Organic Synthesis:
Formation of Carbon-Carbon Bonds; Pergamon: New York, 1986. (b)
Curran, D. P. Synthesis 1988, 417. (c) Curran, D. P. Synthesis 1988,
489. (d) Marthwell, W. B.; Crich, D. Free Radical Chain Reactions in
Organic Synthesis; Academic: New York, 1992. (e) Fart, D. C. Science
1994, 223, 883. (f) Curran, D. P.; Porter, N. A.; Giece, B. Stereochem-
istry of Radical Reactions; VCH: New York, 1996. (g) Radicals in
Organic Synthesis; Renaud, P., Sibi, M. P., Eds.; Wiley-VCH: Wein-
heim, 2001. (h) McCarroll, A. J .; Walton, J . C. Angew. Chem., Int. Ed.
2001, 40, 2224.
(2) For reviews of the chemistry of organotin compounds, see: (a)
Neumann, W. P. Synthesis 1987, 665. (b) RajaBabu, T. V. In Encyclo-
pedia of Reagents for Organic Synthesis; Paquette, T. A., Ed.; Wiley:
New York, 1985. (c) Curran, D. P. Synlett 1991, 63. (d) Curran, D. P.
In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.;
Pergamon: Oxford, 1991; Vol. 4, p 779. (e) Ryu, I.; Sonoda, N.; Curran,
D. P. Chem. Rev. 1996, 96, 177. (f) Ryu, I.; Sonoda, N. Angew. Chem.,
Int. Ed. Engl. 1996, 35, 1050. (g) Davies, A. G. Organotin Chemistry;
VCH: New York, 1997.
(3) For recent reviews on the synthesis and the utilization of 1,2,3-
selenadiazoles, see: (a) Ando, W.; Tokitoh, N. Heteroat. Chem. 1991,
1. (b) Tanaka, R.; Shinkai, I. Prog. Heterocycl. Chem. 1992, 4, 123. (c)
Reid, D. H. In Comprehensive Heterocyclic Chemistry II: A Review of
the Literature 1982-1995; Torr, R. C. S., Ed.; Pergamon: Oxford, 1996;
Vol. 4, p 743. (d) Regitz, M.; Krill, S. Phosphorous, Sulfur Silicon Relat.
Elem. 1996, 15, 99. (e) Zmitrovich, N. I.; Petrov, M. L. Zh. Org. Khim.
1996, 32, 1870. (f) Padmavathi, V.; Sumathi, R. P.; Ramana, R. M. V.;
Bhaskar, R. D. Org. Prep. Proced. Int. 1998, 30, 187 and references
therein.
(4) Meier, H.; Menzel, I. J . Chem. Soc., Chem. Commun. 1971, 1059.
(b) Meier, H.; Hanold, N.; Kolshorn, H. Angew. Chem., Int. Ed. Engl.
1971, 21, 66. (c) Larezari, I.; Shafiee, A. J . Org. Chem. 1971, 36, 2836.
(d) Larezari, I.; Shafiee, A.; Rabest, F.; Yaplani, M. J . Heterocycl. Chem.
1972, 9, 141. (e) Meier, H.; Menzel, I. Tetrehedron Lett. 1972, 445. (f)
Meier, H.; Voigt, E. Tetrahedron 1972, 28, 1987. (g) Laureni, J .; Krantz,
A.; Hanjdu, R. A. J . Am. Chem. Soc. 1976, 98, 7872. (h) Golgolab, H.;
Layer, M.; Combrink, W.; Schniepp, S. Chem. Ber. 1976, 109, 1650. (i)
Krantz, A.; Laureni, J . J . Am. Chem. Soc. 1977, 99, 4842. (j) Bak, B.;
Nielsen, O.; Svanholt, H.; Holm, A. Phys. Lett. 1978, 53, 374. (k) Holm,
A.; Berg, C.; Bjerre, C.; Bak, B.; Svanholt, J . Chem. Soc., Chem.
Commun. 1979, 99. (l) Bak, B.; Nielsen, O.; Svanholt, H. Holm, A.;
Rosenkilde, S. Chem. Phys. Lett. 1981, 78, 301. (m) Meier, H.; Molz,
T.; Merkle, U.; Echter, T.; Lorch, M. Liebigs Ann. Chem. 1982, 914.
(n) Peterso, H.; Meier, H. Chem. Ber. 1984, 114, 2382. (o) Narrit, N.;
Rosenkilde, S.; Larsen, B. D.; Holm, A. J . Chem. Soc., Perkin Trans. 1
1985, 907. (p) Gleiter, R.; Kratz, D.; Schafer, W.; Schehlmann, V. J .
Am. Chem. Soc. 1991, 113, 9258. (q) Guziec, F. S., J r.; SanFilippo, L.
J . J . Org. Chem. 1991, 56, 3178.
reaction of 1,2,3-selenadiazoles derived from cyclic ke-
tones with olefins under thermal conditions and found
that dihydroselenophenes were formed in moderate to
good yields.7 On the other hand, since a report by Clive,8
the reaction of organoselenium compounds with orga-
nostannyl compounds such as R3SnH, allyltributylstan-
(5) Recently, there have been some reports on the synthesis of
organometallic compounds by the reaction of 1,2,3-selenadiazoles with
various organometallic compounds. See: (a) Morley, C. P. Organome-
tallics 1989, 8, 800. (b) Dorrity, M. R. J .; Lavery, A.; Malone, J . F.;
Morley, C. P.; Vaughan, R. R. Heteroat. Chem. 1992, 3, 87. (c) Morley,
C. P.; Vaughan, R. R. J . Chem. Soc., Dalton Trans. 1993, 703. (d)
Morley, C. P.; Vaughan, R. R. J . Chem. Res., Synop. 1995, 64. (f) Ford,
S.; Morley, C. P.; Vaira, M. D. Chem Commun. 1998, 1305.
(6) (a) Ando, W.; Kumamoto, Y.; Tokitoh, N. Tetrahedron Lett. 1986,
27, 6107. (b) Ando, W.; Kumamoto, Y.; Tokitoh, N. Tetrahedron Lett.
1987, 28, 2867. (c) Ando, W.; Kumamoto, Y.; Tokitoh, N. J . Phys. Org.
Chem. 1988, 1, 317. (d) Burkhart, B.; Krill, S.; Okano, Y.; Ando, W.
Regitz, M. Synlett 1991, 356.
(7) Nishiyama, Y.; Hada, Y.; Iwase, K.; Sonoda, N. J . Organomet.
Chem. 2000, 611, 488.
(8) (a) Clive, D. J .; Chittattu, G.; Wong, G. K. J . Chem. Soc., Chem.
Commun. 1978, 41. (b) Nicolaou, K. C.; Gasic, G. P.; Barnette, W. E.
Angew. Chem., Int. Ed. Engl. 1978, 17, 293. (c) Corey, E. J .; Pearce,
H. L.; Szekely, I.; Ishiguro, M. Tetrahedron Lett. 1978, 1023.
10.1021/jo010893t CCC: $22.00 © 2002 American Chemical Society
Published on Web 02/08/2002

1,2,3-Selenadiazole Reaction with Olefins and Dienes
J . Org. Chem., Vol. 67, No. 5, 2002 1521
Sch em e 1
Sch em e 3
Sch em e 2
Sch em e 4
nane, and Bu3SnSnBu3 under radical conditions has often
been used as a method for the generation of carbon-
centered radicals in organic synthesis.9 On the basis of
this information, it is expected that the reaction of 1 with
the tributylstannyl radical should be an excellent method
for the preparation of the vinyl radical intermediate 6
via the attack of the Bu3Sn radical on the selenium atom
of 1, cleavage of the Se-N bond, and denitrogenation
(Scheme 1).
We recently studied the treatment of the 1,2,3-selena-
diazoles 1 with the tributylstannyl radical generated in
situ from Bu3SnH or allyltributylstannane and AIBN in
the presence of olefins or dienes as a radical trapping
agent and found that the reaction of 1,2,3-selenadiazoles
with olefins or dienes 7 was markedly promoted by a
catalytic amount of the tributylstannyl radical under
mild conditions to give the corresponding dihydrosele-
nophenes 8 in moderate to good yields (Scheme 2).10
In the stannyl radical-mediated reactions, the in situ
generated organostannyl radical was converted into
organostannyl compounds having stable Sn-X (X )
halogen or heteroatom function) bonds via the abstraction
of the halogen atom or heteroatom function from R-X
by the stannyl radical. There are only a few examples of
the catalytic use of organostannyl compounds due to the
difficulty in the regeneration of organostannyl radical
from organostannyl compounds having a high stabil-
ity.11,12 Some tributylstannyl hydride-catalyzed reactions
have recently been disclosed: (i) the dehalogenation of
organic halides,13 (ii) the reduction of azides,14 (iii) the
reduction of R,â-unsaturated ketones,15 (iv) the deoxy-
genation of alcohols,16 (v) the reductive cyclization of
enals and enones,17 and (vi) the conversion of nitro-
alkanes to alkanes.18 However, these transformations
require the coexistence of a stoichiometric or excess
amount of a secondary metal hydride such as NaBH3-
CN, Ph2SiH2, or PMHS ((TMSO)(SiHMe)n(TMS)) having
the capability of regenerating Bu3SnH. From this point
of view, this catalytic reaction of 1,2,3-selenadiazoles with
olefins or dienes using tributylstannyl radical is less
common.19 In this paper, the full results of the reaction
of the 1,2,3-selenadiazoles with olefins or dienes in the
presence of a catalytic amount of Bu3SnH and AIBN are
shown.
Resu lts a n d Discu ssion
Dim er iza tion of 1,2,3-Selen a d ia zoles in th e P r es-
en ce of a Ca ta lytic Am ou n t of Tr ibu tylsta n n yl
Hyd r id e or Allyltr ibu tylsta n n a n e a n d AIBN. When
cyclohexeno-1,2,3-selenadiazole (1a ) derived from cyclo-
hexanone was allowed to react with a small excess
amount of allyltributylstannane in the presence of a
catalytic amount of AIBN at 80 °C for 5 h, the 1,4-
diselenine derivative (9a ) was formed in 78% yield
(Scheme 3). When Bu3SnH was employed in place of
allyltributylstannane, the yield of 9a was markedly
decreased due to the formation of complex byproducts.20,21
The reaction pathway shown in Scheme 4 is proposed to
account for the formation of 9a : (i) the attack of the
(9) See for examples: (a) Krief, A.; Hevesi, L. Organoselenium
Chemistry; Springer-Verlag: Berlin, 1988; Vol. 1. (b) Paulmier, C.
Selenium Reagents and Intermediates in Organic Synthesis; Pergamon
Press: Oxford, 1986. (c) Patai, S.; Rappoport, Z. The Chemistry of
Organic Selenium and Tellurium Compounds, 1986; Vols. 1 and 2. (d)
Krief, A. In Comprehensive Organic Synthesis; Trost, B. M., Eds.;
Pergamon Press: Oxford, 1991; Vol. 3 and references therein.
(10) Nishiyama, Y.; Hada, Y.; Anjiki, M.; Hanita, S.; Sonoda, N.
Tetrehedron Lett. 1999, 40, 6293.
(11) Tsai, Y.-M.; Chang, S.-Y. J . Chem. Soc., Chem. Commun. 1995,
981.
(12) As another example of the catalytic use of tributyltin hydride,
intramolecular cyclization of organotin compounds has been reported.
See: (a) Kim, S.; Lee, S. Tetrahedron Lett. 1991, 32, 6575. (b) Spino,
C.; Barriault, N. J . Org. Chem. 1999, 64, 5292.
(13) (a) Corey, E. J .; Suggs, J . W. J . Org. Chem. 1975, 40, 2554. (b)
Stork, G.; Sher, P. M. J . Am. Chem. Soc. 1986, 63, 303.
(14) Hays, D. S.; Fu, G. C. J . Org. Chem. 1998, 63, 2796.
(15) Hays, D. S.; Scholl, M.; Fu, G. C. J . Org. Chem. 1996, 61, 6751.
(16) Lopez, R. M.; Hays, D. S.; Fu, G. C. J . Am. Chem. Soc. 1997,
119, 6949.
(19) More recently, R. E. Maleczka, J r. showed a new approach for
the catalytic use of organotin compounds. See: Terstige, I.; Maleczka,
R. E., J r. J . Org. Chem. 1999, 64, 342.
(20) We suggested that, in the reaction using a small excess amount
of tributylstannyl hydride, the formation of vinyl selenide derivatives
via the reaction of vinyl radical with Bu3SnH and subsequent side
reactions occurred under these reaction conditions to afford the
unidentified byproducts.
(21) It has been reported that the rate constants of SH2 reactions of
alkyl radicals with tributylstannyl hydride22 are known to be much
larger than those with allyltributylstannane.23
(22) Chatgilialoglu, C.; Ingold, K. U.; Scaiano, J . C. J . Am. Chem.
Soc. 1981, 103, 7739.
(17) (a) Hays, D. S.; Fu, G. C. J . Org. Chem. 1996, 61, 4. (b) Hays,
D. S.; Fu, G. C. Tetrahedron 1999, 55, 8815.
(18) Tormo, J .; Hays, D. S.; Fu, G. C. J . Org. Chem. 1998, 63, 5296.
(23) Curran, D. P.; van Elburg, P. A.; Giese, B.; Gilges, S. Tetrahe-
dron Lett. 1990, 31, 2861.

1522 J . Org. Chem., Vol. 67, No. 5, 2002
Nishiyama et al.
Ta ble 1. Tr ea tm en t of 1a w ith a Ca ta lytic Am ou n t of
Or ga n osta n n yl Com p ou n d a n d Ra d ica l In itia tor a
Sch em e 6
yield (%)b
entry
Bu3SnR
initiator
9a
10a
1
Bu3SnCH2CHdCH2
Bu3SnH
AlBN
81
77
80
71
17
7
15
6
2
AlBN
3c
4d
5e
Bu3SnH
AMVN
Et3B/O2
none
Bu3SnH
none
5
2
a
Reaction conditions: 1a (0.5 mmol), Bu3SnR (0.025 mmol),
radical initiator (0.0125 mmol), and benzene (2.5 mL) at 80 °C for
b
d
5 h. GC yield. c At 60 °C. At 25 °C. e 1a (77%) was recovered.
Sch em e 5
tributylstannyl radical generated in situ from Bu3SnH/
AIBN or allyltributylstannane/AIBN on the selenium
atom of 1a , followed by cleavage of the Se-N bond, (ii)
denitrogenation to form the vinyl radical species 6a , (iii)
attack of the vinyl radical 6a on the selenium atom of
another molecule of 1a , (iv) cleavage of the Se-N bond
and elimination of the nitrogen molecule, and (v) in-
tramolecular SH2 reaction of vinyl radical to form 9a and
the regeneration of the tributylstannyl radical. From the
result with the use of allyltributylstannane, the catalytic
use of organostannyl compounds has been expected. In
fact, when 1,2,3-selenadiazole 1a derived from cyclohex-
anone was treated with a catalytic amount of allyltribu-
tylstannane (0.05 mol %) and AIBN (2.5 mol %) in
benzene solvent at 80 °C for 5 h, the 1,4-diselenine
derivative 9a was formed in 81% yield along with a 7%
yield of the selenophene derivative 10a (entry 1 in Table
1). Table 1 shows the results of the treatment of 1a with
a catalytic amount of organostannyl compounds under
various reaction conditions. In the absence of Bu3SnH
and AIBN at 80 °C for 5 h, the yield of 9a was markedly
decreased and 1a (77%) was recovered (entry 5).14 It is
interesting to note that the catalytic use of tributylstan-
nyl hydride instead of allyltributylstannane also led to
the 77% yield of 9a (entry 2). When diazavaleronitrile
(AMVN) or Et3B/O2 was used instead of AIBN as the
radical initiator, the reaction occurred at a lower reaction
temperature, giving 9a in 80% or 71% yield, respectively
(entries 3 and 4). For cyclohexeno-1,2,3-thiadiazole, the
similar reaction did not take place, and thiadiazole (98%)
was recovered (Scheme 5).
R ea ct ion of 1,2,3-Selen a d ia zoles w it h Va r iou s
Olefin s. On the basis of the proposed reaction pathway
for the formation of 9a , the synthesis of dihydrosele-
nophene 8 by the addition of a vinyl radical species (6a )
to the carbon-carbon double bond of olefins followed by
intramolecular cyclization was examined (Scheme 6).
When 1a was allowed to react with an excess amount of
ethyl acrylate (7a ) (200 equiv) in the presence of Bu3-
SnH/AIBN reagent at 80 °C for 5 h, the corresponding
dihydroselenophene 8a , the 1:1 addition product of 1a
and 7a , was formed in 77% yield along with 9a (8%)
(entry 4 in Table 2). The decrease in the amount of 7a
led to a decrease in the yield of 8a (entries 1-4). Also,
the yield of 8a was improved by the addition of a small
amount of hydroquinone to prevent the oligomerization
of 7a (entry 6).24 Table 3 shows the results of the reaction
of 1a with various olefins in the presence of a catalytic
Ta ble 2. Rea ction of 1a w ith 7a a
yield (%)b
amt of 7a
entry
(equiv)
8a
26
9a
1
2
3
10
50
45
33
18
8
15
9
56
100
200
200
200
68
77
72
86 (75)
4
5c
6d
a
Reaction conditions: 1a (0.5 mmol), Bu3SnH (0.025 mmol),
radical initiator (0.0125 mmol), 7a , and benzene (2.5 mL) at 80
b
°C for 5 h. GC yield. The number in parentheses shows the
d
isolated yield. c In the absence of benzene. Hydroquinone (0.05
mmol) was added.
amount of Bu3SnH/AIBN. For the reaction of methyl
acrylate, acrylonitrile, and methyl vinyl ketone, the
addition products were formed in 79%, 67%, and 74%
yields, respectively (entries 1, 4, and 5). The use of
R-methyl-substituted R,â-unsaturated esters such as
methyl methacrylate also provided the corresponding
dihydroselenophene in 51% yield (entry 2). In contrast
to the reaction of methyl methacrylate, when methyl
crotonate, in which the methyl group is substituted at
the â-position, was used as an olefin, 1,4-diselenine 9a
was obtained as the main product (entry 3). Styrene also
gave the corresponding addition product in 76% yield
(entry 6). However, for butyl vinyl ether, vinyl acetate,
and 1-octene, the yields of the addition products were
very low due to the predominant formation of 9a (entries
7-9).
Next, 1,2,3-selenadiazole 1a was treated with dienes
in the presence of a catalytic amount of the Bu3Sn radical,
(24) We cannot explain in detail the reason for the improvement in
the yields of addition products in the presence of hydroquinone.
However, we suggest that the attack of the Bu3Sn radical on 1,2,3-
selenadiazole, the addition of the vinyl radical to the carbon-carbon
double bond, and the intramolecular cyclization were faster than the
reaction of the tributylstannyl radical with hydroquinone.

1,2,3-Selenadiazole Reaction with Olefins and Dienes
J . Org. Chem., Vol. 67, No. 5, 2002 1523
Ta ble 3. Rea ction of 1a w ith Olefin sa
Ta ble 4. Rea ction of 1a w ith Dien esa
a
Reaction conditions: 1a (0.5 mmol), Bu3SnCH2CHdCH2 (0.025
mmol), AIBN (0.0125 mmol), hydroquinone (0.05 mmol), diene (100
b
mmol), and benzene (2.5 mL) at 80 °C for 5 h. Isolated yield.
c Bu3SnH was used.
Ta ble 5. Rea ction of Va r iou s 1,2,3-Selen a d ia zoles w ith
Eth yl Acr yla tea
a
Reaction conditions: 1a (0.5 mmol), Bu3SnH (0.025 mmol),
AIBN (0.0125 mmol), hydroquinone (0.05 mmol), olefin (100 mmol),
b
and benzene (2.5 mL) at 80 °C for 5 h. GC yield. The numbers
in parentheses show the isolated yields. c 9a (66%) was formed.
d
Mixture of stereoisomers (9:1). e 9a (56%) was formed. f 9a (67%)
g
was formed. 9a (67%) was formed.
and these results are shown in Table 4. When 1a was
reacted with 2,3-dimethylbutadiene in the presence of a
catalytic amount of Bu3SnH and AIBN, the addition of
the vinyl radical 6a to the carbon-carbon double bond
of the diene followed by cyclization proceeded to give the
corresponding dihydroselenophene, the 1,2-addition prod-
uct, in 58% yield (entry 1). In this reaction, when
allyltributylstannane instead of Bu3SnH was used as an
organostannyl compound, the yield of the addition prod-
uct was slightly increased (entry 2). For the reaction of
isoprene, a mixture of 1,2-addition products was formed
in 68% yield (entry 3). On the other hand, for 1,5-
hexadiene, 1,4-diselenine was predominantly obtained
(entry 4).
Rea ction of Va r iou s 1,2,3-Selen a d ia zoles w ith
Eth yl Acr yla te. Various 1,2,3-selenadiazoles were re-
acted with ethyl acrylate (7a ) (200 equiv) in the presence
of a catalytic amount of Bu3SnH and AIBN, and the
results are shown in Table 5. When the 1,2,3-selenadi-
azoles prepared from 2-methyl- and 4-methylcyclohex-
anone were allowed to react with 7a , the addition of vinyl
radicals generated in situ from the 1,2,3-selenadiazoles
to 7a efficiently proceeded to afford the corresponding
a
Reaction conditions: 1,2,3-selenadiazole (0.5 mmol), Bu3SnH
(0.025 mmol), AIBN (0.0125 mmol), hydroquinone (0.05 mmol),
ethyl acrylate (100 mmol), and benzene (2.5 mL) at 80 °C for 5 h.
b
GC yield. The numbers in parentheses show the isolated yields.
c Mixture of stereoisomers (1:1). Mixture of stereoisomes (3:2).
d
e 1,2,3-Selenadiazole (40%) was recovered. Diselenine 9 was formed
in 11% yield. f 1,2,3-Selenadiazole (52%) was recovered. Diselenine
9 was formed in 13% yield.
dihydroselenophenes in 73% and 75% yields, respectively
(entries 1 and 2). Similarly, 1,2,3-selenadiazole derived
from cyclopentanone gave the corresponding dihydro-
selenophene in 66% yield (entry 3). In the case of 1,2,3-
selenadiazole prepared from cycloheptanone and cyclo-
octanone, the yields of the addition product were low
(entries 4 and 5). For the reaction of 1,2,3-selenadiazole
derived from acetophenone and dibutyl ketone, the
corresponding dihydroselenophene and 1,4-diselenines
were not isolated, and phenylacetylene and 4-nonyne
were produced as the sole products (Scheme 7).

1524 J . Org. Chem., Vol. 67, No. 5, 2002
Nishiyama et al.
compounds.4c The other reagents and solvents were purified
by the usual methods before use.
Sch em e 7
Gen er a l P r oced u r e for th e Dim er iza tion of 1,2,3-
Selen a d ia zoles in th e P r esen ce of a Ca ta lytic Am ou n t
of Bu 3Sn H a n d AIBN. 1,2,3-Selenadiazloles (0.5 mmol), Bu3-
SnH (0.0025 mmol), AIBN (0.00125 mmol), and benzene (2.5
mL) were added to a 20 mL flask, and the mixture was stirred
at 80 °C for 5 h under a nitrogen atmosphere. After the
reaction was complete, benzene was removed under reduced
pressure and purified by column chromatography on silica gel
(n-C6H14:CHCl3 ) 7:1 as the eluent) to afford 2a and 3a . The
products were characterized by comparison of their spectra
with those of authentic samples. The structures of the products
were assigned on the basis of the 1H and 13C NMR, IR, and
GC-mass spectra.
Sch em e 8. P la u sible Rea ction P a th s
Da ta for 9a : 1H NMR (CDCl3) δ 1.69-1.74 (m, 8H), 2.45-
2.48 (m, 8H); 13C NMR (CDCL3) δ 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
.
Da ta for 10a : 1H NMR (CDCl3) δ 1.75-1.84 (m, 8H), 2.17-
2.37 (m, 4H), 2.76-2.77 (m, 4H); 13C NMR (CDCl3) δ 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
.
Gen er a l P r oced u r e for th e Rea ction of 1,2,3-Selen a -
d ia zoles w ith Olefin s or Dien es in th e P r esen ce of a
Ca ta lytic Am ou n t of Bu 3Sn H a n d AIBN. 1,2,3-Selenadi-
azole (0.5 mmol), olefin (100 mmol), Bu3SnH (0.0025 mmol),
AIBN (0.00125 mmol), hydroquinone (0.05 mmol), and benzene
(2.5 mL) were added to a 20 mL flask, and the mixture was
stirred at 80 °C for 5 h under a nitrogen atmosphere. After
the reaction was complete, benzene and the volatile excess
olefin were removed under reduced pressure and purified by
column chromatography on silica gel (n-C6H14:CHCl3 ) 1:1 as
the eluent) to afford the dihydroselenophene, 1,4-diselenine,
and selenophene derivatives. The structures of the products
were assigned on the basis of the 1H and 13C NMR, IR, and
GC-mass spectra.
The different behaviors observed among the 1,2,3-
selenadiazoles may be explained in terms of the differ-
ence in the geometry of the 1,2,3-selenadiazoles (Scheme
8). The attack of the tributylstannyl radical on the
selenium atom of 1 and cleavage of the selenium-
nitrogen bond successively occurred to generate the
radical species 11. In the case of 1,2,3-selenadiazoles
derived from cyclic ketones, the denitrogenation from 11
to form the vinyl radical 6, addition of 6 to the carbon-
carbon double bond, and intramolecular cyclization
smoothly proceeded to afford the corresponding dihy-
droselenophenes 8 (path 1). On the other hand, for the
reaction of 1,2,3-selenadiazoles derived from linear and
aromatic ketones, the fast â-fragmentation of Bu3SnSe
radical from 6 or the concerted elimination of the Bu3-
SnSe radical and nitrogen molecule from 11 via the
transition state 12 predominantly proceeded to give the
corresponding alkynes (path 2).
Da ta for 8a : 1H NMR (CDCl3) δ 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 (d, 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) δ
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, 1733, 2834, 2931, 2979 cm-1
.
Da ta for 8b: 1H NMR (CDCl3) δ 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) δ 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, 1262, 1293, 1329, 1435, 1737,
2835, 2855, 2930 cm-1
.
Da ta for 8c: 1H NMR (CDCl3) δ 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) δ 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,
In summary, we found that the reaction of 1,2,3-
selenadiazoles with olefins and dienes was promoted by
the catalytic amount of the tributylstannyl radical to give
the corresponding dihydroselenophenes in moderate to
good yields.
1260, 1274, 1307, 1349, 1436, 1732, 2856, 2928 cm-1
.
Da ta for 8d (m ixtu r e of ster eoisom er s): 1H NMR
(CDCl3) δ 1.12 (d, J ) 7.0 Hz, 2.7 H), 1.45 (d, J ) 7.0 Hz, 0.3
H), 1.54-1.74 (m, 4H), 1.95-2.25 (m, 4H), 2.98-3.06 (m, 0.1
H), 3.20-3.28 (m, 0.9 H), 3.72 (s, 0.3 H), 3.73 (s, 2.7 H), 3.97
(d, J ) 5.5 Hz, 0.9 H), 4.58 (d, J ) 7.7 Hz, 0.1 H); 13C NMR
(CDCl3) δ 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, 1272, 1341, 1434, 1736, 2835, 2929
Exp er im en ta l Section
Gen er a l P r oced u r es. 1H and 13C NMR spectra were
recorded on a J EOL J NM-GSX-400 (400 and 99.5 MHz)
spectrometer using CDCl3 as the solvent with tetramethyl-
silane as an internal standard. FT-IR spectra were obtained
using a Perkin-Elmer model PARAGON 1000 spectrophotom-
eter. Mass spectra were measured on a Shimadzu model QP-
5050A instrument. Gas chromatography (GC) was carried out
on a Shimadzu GC-14A instrument equipped with a flame
ionizing detector and using a capillary column (Hicap-CBP-
1-S25-0.25, 0.25 mm × 25 m). Selenium dioxide, ketones,
aldehydes, semicarbazide hydrochloride, and acetic acid were
commercially available high-grade products and were used
without purification. 1,2,3-Selenadiazoles were prepared by the
reaction of selenium dioxide with semicarbazones prepared by
the reaction of semicarbazide hydrochloride with carbonyl
cm-1
.
Da ta for 8e: 1H NMR (CDCl3) δ 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) δ 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, 2855, 2928 cm-1
.
Da ta for 8f: 1H NMR (CDCl3) δ 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) δ 22.2,
23.6, 27.2, 27.4, 27.8, 41.5, 47.6, 124.7, 132.3, 203.9; IR (neat)

1,2,3-Selenadiazole Reaction with Olefins and Dienes
827, 994, 1062, 1168, 1201, 1239, 1263, 1317, 1353, 1438, 1705,
J . Org. Chem., Vol. 67, No. 5, 2002 1525
124.9, 125.0, 131.1, 131.2, 174.0, 174.1; IR (neat) 1153, 1179,
2833, 2855, 2928 cm-1
.
1204, 1324, 1368, 1733, 2832, 2850, 2921, 2951 cm-1
.
Da ta for 8o (m ixtu r e of ster eoisom er s): 1H NMR
(CDCl3) δ 1.03 (d, J ) 7.2 Hz, 1.80H), 1.08 (d, J ) 7.2 Hz,
1.20H), 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,
0.60H), 4.40 (dd, J ) 3.2, 7.2 Hz, 0.40H); 13C NMR (CDCl3) δ
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)
Da ta for 8g: 1H NMR (CDCl3) δ 1.66-1.76 (m, 4H), 2.07-
2.09 (m, 2H), 2.23-2.25 (m, 2H), 2.87-2.96 (m, 1H), 3.02-
3.10 (m, 1H), 5.01 (dd, J ) 7.3, 8.4 Hz, 1H), 7.18-7.39 (m,
5H); 13C NMR (CDCl3) δ 22.6, 23.8, 27.9, 28.0, 45.9, 49.9, 127.1,
127.2, 127.4, 128.7, 130.9, 144.9; IR (neat) 696, 761, 996, 1031,
1075, 1125, 1157, 1238, 1249. 1260, 1304, 1349, 1452, 1492,
1600, 1653, 2829, 2854, 2927, 3025, 3059 cm-1
.
Da ta for 8h : 1H NMR (CDCl3) δ 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) δ 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,
1180, 1209, 1318, 1322, 1732, 2852, 2927, 2957 cm-1
.
Da ta for 8p : 1H NMR (CDCl3) δ 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) δ
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, 1325, 1368, 1444, 1733, 2847, 2955
1438, 1654, 1735, 2871, 2929 cm-1
.
Da ta for 8i: 1H NMR (CDCl3) δ 1.62-1.79 (m, 4H), 2.06
(s, 3H), 2.02-2.36 (m, 4H), 2.84 (td, J ) 1.2, 13.2 Hz, 1H),
3.03-3.13 (m, 1H), 6.45 (dd, J ) 1.1, 7.0 Hz, 1H); 13C NMR
(CDCl3) δ 21.6, 22.3, 23.6, 27.5, 27.6, 48.1, 75.3, 126.6, 129.1,
170.6; IR (neat) 726, 826, 895, 976, 1014, 1111, 1131, 1149,
cm-1
.
Da ta for 9p : 1H NMR (CDCl3) δ 2.07-2.15 (m, 4H), 2.43
(t, J ) 7.3 Hz, 8H); 13C NMR (CDCl3) δ 25.0, 37.2, 125.0; IR
(neat) 865, 1024, 1108, 1201, 1238, 1305, 1442, 1597, 2840,
2903, 2950 cm-1
.
1201, 1231, 1304, 1371, 1439, 1742, 2855, 2928 cm-1
.
Da ta for 8q: 1H NMR (CDCl3) δ 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) δ 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,
Da ta for 8j: 1H NMR (CDCl3) δ 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) δ 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, 988, 1165, 1261, 1376, 1457, 1541, 1654, 1734, 2854,
1178, 12,7, 1325, 1367, 1444, 1732, 2848, 2920, 2978 cm-1
.
2925 cm-1
.
Da ta for 9q: 1H NMR (CDCl3) δ 1.51-1.57 (m, 8H), 1.72-
1.78 (m, 4H), 2.62-2.65 (m, 8H); 13C NMR (CDCl3) δ 26.6, 31.9,
37.7, 135.1; IR (neat) 712, 766, 820, 970, 1075, 1124, 1214,
Da ta for 8k : 1H NMR (CDCl3) δ 1.60-1.74 (m, 4H), 1.71
(t, J ) 4.8 Hz, 3H), 1.94 (t, J ) 0.8 Hz, 3H), 2.03-2.09 (m,
2H), 2.20-2.23 (m, 4H), 2.31-2.39 (m, 1H), 2.88-2.97 (m, 1H),
4.76 (dd, J ) 0.8, 0.8 Hz, 1H), 4.84 (d, J ) 0.8 Hz, 1H); 13C
NMR (CDCl3) δ 21.9, 22.7, 23.9, 28.1. 29.2, 30.0, 53.6, 59.9,
109.5, 127.7, 131.0, 150.0; IR (neat) 890, 997, 1373, 1439, 1458,
1274, 1358, 1431, 1587, 2829, 2844, 2873, 2922 cm-1
.
Da ta for 8r : 1H NMR (CDCl3) δ 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) δ 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, 1206, 1326, 1367, 1445, 1462, 1731, 2849,
2830, 2856, 2927, 3089 cm-1
.
Da ta for 8l (m ixtu r e of isom er s): 1H NMR (CDCl3)
δ1.56-1.74 (m, 6H), 1.84 (t, J ) 0.8 Hz, 1.95H), 2.02-2.08
(m, 2H), 2.17-2.23 (m, 2H), 2.40-2.46 (m, 0.35H), 2.61-2.87
(m, 0.70H), 4.53 (t, J ) 8.8 Hz, 0.65H), 4.71 (t, J ) 1.6 Hz,
0.65H), 4.85 (d, J ) 1.6 Hz, 0.65H), 4.91 (dd, J ) 10.4, 0.8 Hz,
0.35H), 5.02 (dd, J ) 17.2, 0.8 Hz, 0.35H), 6.30 (dd, J ) 10.4,
17.2 Hz, 0.35H); 13C NMR (CDCl3) δ 20.0, 22.5, 22.6, 23.8, 23.9,
27.5, 27.9, 28.0, 28.1, 28.2, 46.2, 48.9, 54.9, 55.4, 55.9, 110.2,
110.6, 127.9, 130.1, 131.5, 145.0; IR (neat) 897, 996, 1064, 1533,
2922. 2978 cm-1
.
Da ta for 9r : 1H NMR (CDCl3) δ 1.43-1.48 (m, 8H), 1.60-
1.64 (m, 8H), 2.53-2.60 (m, 4H); 13C NMR (CDCl3) δ 26.5, 30.0,
34.8, 133.1; IR (neat) 733, 779, 831, 879, 1017, 1126, 1253,
1308, 1322, 1353, 1439, 1458, 1592, 2844, 2907 cm-1
.
1440, 2830, 2856, 2926, 3081 cm-1
.
Ack n ow led gm en t. This work has been financially
supported by a Grant-in-Aid for Scientific Research from
the J apan Society for the Promotion of Science.
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
and IR spectra for all compounds. This material is available
free of charge via the Internet at http://pubs.acs.org.
Da ta for 8n (m ixtu r e of ster eoisom er s): 1H NMR
(CDCl3) δ 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, 3H), 2.18-2.23 (m, 1H), 2.72-2.88 (m, 1H),
3.04-3.18 (m, 1H), 4.12-4.21 (m, 2H), 4.43 (dt, J ) 4.0, 7.2
Hz, 1H); 13C NMR (CDCl3) δ 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,
J O010893T