Synthesis and reactivity of allenes substituted by selenenyl groups at 1- and 3-positions

Article abstract of DOI:10.1021/jo001483s

1,3-Bis(methylseleno)- and 1,3-bis(benzylseleno)-l,3-diphenylpropadienes were synthesized by reaction of Ph₂C₃ dianion, prepared from 1,3-diphenylpropyne and n-butyllithium, with dimethyl diselenide or benzylselenocyanate in the presence of TMEDA, and reaction of the dianion with a mixture of dimethyl diselenide and benzylselenocyanate yielded 1-benzylseleno-3-methylselenoallene along with the symmetric allenes. Diselenocyclic allenes and tetraselenocyclic bisallenes were also obtained by reacting the dianion with corresponding alkane diselenocyanates. The thermal reaction of the 1,3-bis(alkylseleno)allenes mainly afforded enediynes through radical pathway, and the nine-membered cyclic allene provided intramolecular cyclization product via an intramolecular rearrangement. Heating of the cyclic bisallenes gave compounds derived from intramolecular cyclization products together with a small amount of the enediynes. Irradiation of allenes caused rearrangement of the selenenyl group to give alkynes, and the alkynes also reacted photochemically to yield the enediynes.

Full text of DOI:10.1021/jo001483s

J . Org. Chem. 2001, 66, 1787-1794
1787
Syn th esis a n d Rea ctivity of Allen es Su bstitu ted by Selen en yl
Gr ou p s a t 1- a n d 3-P osition s
Toshio Shimizu, Daisuke Miyasaka, and Nobumasa Kamigata*
Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minami-ohsawa,
Hachioji, Tokyo 192-0397, J apan
kamigata-nobumasa@c.metro-u.ac.jp
Received October 16, 2000
1,3-Bis(methylseleno)- and 1,3-bis(benzylseleno)-1,3-diphenylpropadienes were synthesized by
reaction of Ph2C3 dianion, prepared from 1,3-diphenylpropyne and n-butyllithium, with dimethyl
diselenide or benzylselenocyanate in the presence of TMEDA, and reaction of the dianion with a
mixture of dimethyl diselenide and benzylselenocyanate yielded 1-benzylseleno-3-methylselenoallene
along with the symmetric allenes. Diselenocyclic allenes and tetraselenocyclic bisallenes were also
obtained by reacting the dianion with corresponding alkane diselenocyanates. The thermal reaction
of the 1,3-bis(alkylseleno)allenes mainly afforded enediynes through radical pathway, and the nine-
membered cyclic allene provided intramolecular cyclization product via an intramolecular rear-
rangement. Heating of the cyclic bisallenes gave compounds derived from intramolecular cyclization
products together with a small amount of the enediynes. Irradiation of allenes caused rearrangement
of the selenenyl group to give alkynes, and the alkynes also reacted photochemically to yield the
enediynes.
In tr od u ction
the selenium-substituted allenes are different from those
of corresponding sulfur-substituted allenes. In this paper,
we report the synthesis, thermal reaction, and photo-
chemical reaction of 1,3-bis(alkylseleno)allenes, disele-
nocyclic allenes, and tetraselenocyclic bisallenes.6
Allenes are reactive species with cumulated double
bonds and are useful intermediates for organic synthesis.
Many studies have been performed on their preparation
and reactivity.1,2 Sulfur-substituted allenes have also
been synthesized in the 1960s,3 except for 1,3-disulfenyl
allene. Recently, we reported the synthesis and reaction
of allenes substituted by sulfenyl groups at 1- and
3-positions, and thermal reactions of the 1,3-bis(alkylth-
io)allenes have been found to give thiophene derivatives,
and the irradiation afforded the 1,3-rearrangement prod-
ucts.4 Several selenium-substituted allenes are also
known as isolable compounds or reactive intermediates;5
however, few of their reactivities have been examined.
We synthesized 1,3-bis(alkylseleno)allenes by reacting
Ph2C3 dianion with the corresponding diselenide or
selenocyanates, and it was found that the reactivities of
Resu lts a n d Discu ssion
Syn th esis of Selen iu m -Su bstitu ted Allen es. Reac-
tion of Ph2C3 dianion (1,3-dilithiated allene), prepared
from 1,3-diphenylpropyne and n-butyllithium, with 2
equiv of dimethyl diselenide in the presence of TMEDA
(N,N,N′,N′-tetramethylethylenediamine) yielded 1,3-bis-
(methylseleno)-1,3-diphenylpropadiene (1) in 70% yield
(Scheme 1). In this reaction, addition of TMEDA was
found to be effective, and the yield was lowered (22%)
when the reaction was carried out without TMEDA.
Reaction of the dianion with 2 equiv of benzylselenocy-
anate in the presence of TMEDA also provided 1,3-bis-
(benzylseleno)-1,3-diphenylpropadiene (2) in 64% yield.
Similarly, reaction of the dianion with a mixture of
dimethyl diselenide and benzylselenocyanate afforded
unsymmetric allene 3 in 17% yield along with symmetric
allenes 1 (26%) and 2 (5%). 3,3-Bis(alkylseleno)-1,3-
diphenylpropyne, formation of which is also anticipated
from the reaction, was not found in either reaction,
whereas reaction of the dianion with ethyl bromide
yielded 1,3-diphenyl-3-ethyl-1-pentyne as a major prod-
uct.4 The reason the propyne was not formed might be
explained based on the steric effect; the introduction of
* To whom correspondence should be addressed. Telephone: +81
(426) 77-2556. Fax: +81 (426) 77-2525.
(1) For reviews, see: (a) The Chemistry of the Allenes; Landor, S.
R., Ed.; Academic Press: New York, 1982; Vols. 1-3. (b) The Chemistry
of Ketenes, Allenes and Related Compounds; Patai, S., Ed.; Wiley: New
York, 1980; Vols. 1 and 2. (c) Brandsma, L.; Verkruijsee, H. D.
Synthesis of Acetylenes, Allenes and Cumulenes; Elsevier: New York,
1980. (d) Pasto, D. J . Tetrahedron 1984, 40, 2805. (e) Smadja, W. Chem.
Rev. 1983, 83, 263. (f) Baldwin, J . E.; Fleming, R. H. Fortschr. Chem.
Forsch. 1970, 15, 281. (g) Huche´, M. Tetrahedron 1980, 36, 331. (h)
Mavrov, M. V.; Kucherov, V. F. Russ. Chem. Rev. 1967, 36, 233. (i)
Griesbaum, K. Angew. Chem., Int. Ed. Engl. 1966, 5, 933.
(2) For reviews, see: (a) Bruneau, C.; Dixneuf, P. H. Compr. Org.
Funct. Group Transform. 1995, 1, 953. (b) Marshall, J . A. Chem. Rev.
1996, 96, 31. (c) Schuster, H. F.; Coppola, G. M. Allenes in Organic
Synthesis; Wiley: New York, 1984. (d) Taylor, D. R. Chem. Rev. 1967,
67, 317.
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Sci. 1961, 252, 1630. (b) Pourcelot, G.; Le Quan, M.; Simonnin, M.-P.;
Cadiot, P. Bull. Soc. Chim. France 1962, 1278. (c) Brandsma, L.; Wijers,
H. E.; Arens, J . F. Rec. Trav. Chim. Pays-Bas 1963, 82, 1040. (d)
Wildschut, G. A.; van Boom, J . H.; Brandsma, L.; Arens, J . F. Rec.
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L.; Arens, J . F. Recl. Trav. Chim. Pays-Bas 1969, 88, 1132.
(4) (a) Shimizu, T.; Sakamaki, K.; Kamigata, N. Tetrahedron Lett.
1997, 38, 8529. (b) Shimizu, T.; Sakamaki, K.; Miyasaka, D.; Kamigata,
N. J . Org. Chem. 2000, 65, 1721.
(5) (a) Pourcelot, G.; Cadiot, P. Bull. Soc. Chim. Fr. 1966, 3016; 3024.
(b) Petrov, M. L.; Radchenko, S. I.; Kupin, V. S.; Petrov, A. A. J . Org.
Chem. U.S.S.R. 1973, 9, 683. (c) Braverman, S.; Duar, Y. Tetrahedron
Lett. 1978, 1493. (d) Braverman, S.; Freund, M.; Goldberg, I. Tetra-
hedron Lett. 1980, 21, 3617. (e) Reich, H. J .; Shah, S. K.; Gold, P. M.;
Olson, R. E. J . Am. Chem. Soc. 1981, 103, 3112. (f) Reich, H. J .; Kelly,
M. J . J . Am. Chem. Soc. 1982, 104, 1119. (g) Tada, M.; Nagasaka, R.
Bull. Chem. Soc. J pn. 1995, 68, 3221.
(6) For a preliminary communication, see: Shimizu, T.; Miyasaka,
D.; Kamigata, N. Org. Lett. 2000, 2, 1923.
10.1021/jo001483s CCC: $20.00 © 2001 American Chemical Society
Published on Web 02/10/2001

1788 J . Org. Chem., Vol. 66, No. 5, 2001
Shimizu et al.
Sch em e 1
Sch em e 2
F igu r e 1. Crystal structure of 4b showing 50% probability
displacement ellipsoids. Selected bond lengths (Å) and bond
angles (deg): Se(1)-C(1), 1.944(4); Se(1)-C(6), 1.950(4); Se-
(2)-C(3), 1.947(4); Se(2)-C(8), 1.952(4); C(1)-C(2), 1.312(5);
C(1)-C(4), 1.472(5); C(2)-C(3), 1.303(5); C(3)-C(5), 1.467(5);
C(1)-Se(1)-C(6), 99.3(2); C(3)-Se(2)-C(8), 98.5(1); Se(1)-
C(1)-C(2), 116.6(3); Se(1)-C(1)-C(4), 118.0(3); C(2)-C(1)-
C(4), 125.4(4); C(1)-C(2)-C(3), 166.5(4); Se(2)-C(3)-C(2),
117.3(3); Se(2)-C(3)-C(5), 118.2(3); C(2)-C(3)-C(5), 124.5(3).
tetraphenyl-3-hexen-1,5-diynes (6 and 7), the framework
of which is known as an important building block of
several naturally occurring antitumor antibiotics7 and as
a substrate of the Masamune-Bergman reaction,8 were
obtained in 34% and 7% yields, respectively, together
with (Z,Z)-3,4-bis{R-(methylseleno)benzylidene}-1,2-diphe-
nylcyclobutene (8) (21%) and the E,Z-isomer 9 (9%)
(Scheme 2). The structure of enediynes 6 and 7 was
confirmed by X-ray crystallographic analysis of E-isomer
6.6 The stereochemistry of Z,Z-isomer 8 was also deter-
mined by X-ray analysis, as shown in Figure 2. Dihedral
angle C(5)-C(3)-C(4)-C(6) of 8 is twisted (24°) in the
crystalline state perhaps due to repulsion of two selenium
two bulky selenenyl groups on the same carbon would
be difficult.
The dianion also reacted with ethane 1,2-diselenocy-
anate to afford 14-membered cyclic bisallene 5a in 26%
yield (dl/ meso ≈ 1/2). Stereochemistry of the dl- and
meso-isomers was assigned in comparison of their 1H
NMR spectra with those of sulfur analogue, whose
structure has been determined by X-ray analysis of the
meso-isomer.4 Similarly, selenium-substituted, larger-
membered cyclic bisallenes 5b and 5c were also obtained
in yields of 1% (dl/ meso ≈ 1/1) and 14% (dl/ meso ≈ 1/1),
respectively, by reacting the dianion with corresponding
alkane diselenocyanates. In these reactions, cyclic monoal-
lenes 4b and 4c were also obtained in 57% and 14%
yields, respectively, whereas the corresponding sulfur-
substituted cyclic monoallene has not been obtained by
the reaction of the dianion with corresponding alkane
dithiocyanates.4 This difference is maybe due to the
difference of configuration in the ring-closure reaction.
The crystal structure of eight-membered cyclic monoal-
lene 4b was determined by X-ray analysis, as shown in
Figure 1. The bond lengths are almost normal, and bond
angle C(1)-C(2)-C(3) and torsion angle Se(1)-C(1)-
C(3)-Se(2) are 167° and 75°, respectively, indicating a
slightly strained structure.
(7) (a) Golik, J .; Clardy, J .; Dubay, G.; Groenewold, G.; Kawaguchi,
H.; Konishi, M.; Krishnan, B.; Ohkuma, H.; Saitoh, K.; Doyle, T. W.
J . Am. Chem. Soc. 1987, 109, 3461. (b) Nicolaou, K. C.; Ogawa, Y.;
Zuccarello, G.; Kataoka, H. J . Am. Chem. Soc. 1988, 110, 7247. (c)
Nicolaou, K. C.; Dai, W.-M.; Wendeborn, S. V.; Smith, A. L.; Torisawa,
Y.; Maligres, P.; Hwang, C.-K. Angew. Chem., Int. Ed. Engl. 1991, 30,
1032. (d) Nicolaou, K. C.; Dai, W.-M. Angew. Chem., Int. Ed. Engl.
1991, 30, 1387. (e) Nicolaou, K. C.; Smith, A. L. Acc. Chem. Res. 1992,
25, 497. (f) Nicolaou, K. C.; Liu, A.; Zeng, Z.; McComb, S. J . Am. Chem.
Soc. 1992, 114, 9279. (g) Nicolaou, K. C. Angew. Chem., Int. Ed. Engl.
1993, 32, 1377. (h) Kagan, J .; Wang, X. D.; Chen, X. S.; Lau, K. Y.;
Batac, I. V.; Tuveson, R. W.; Hudson, J . B. J . Photochem. Photobiol.,
B 1993, 21, 135. (i) Wender, P. A.; Zercher, C. K.; Beckham, S.;
Haubold, E.-M. J . Org. Chem. 1993, 58, 5867.
(8) (a) Darby, N.; Kim, C. U.; Salau¨n, J . A.; Shelton, K. W.; Takada,
S.; Masamune, S. J . Chem. Soc., Chem. Commun. 1971, 1516. (b) J ones,
R. R.; Bergman, R. G. J . Am. Chem. Soc. 1972, 94, 660. (c) Bergman,
R. G. Acc. Chem. Res. 1973, 6, 25. (d) Wong, H. N. C.; Sondheimer, F.
Tetrahedron Lett. 1980, 21, 217. (e) Lockhart, T. P.; Bergman, R. G.
J . Am. Chem. Soc. 1981, 103, 4091. (f) Ramkumar, D.; Kalpana, M.;
Varghese, B.; Sankararaman, S.; J agadeesh, M. N.; Chandrasekhar,
J . J . Org. Chem. 1996, 61, 2247. (g) Evenzahav, A.; Turro, N. J . J .
Am. Chem. Soc. 1998, 120, 1835.
Th er m a l Rea ction of Selen iu m -Su bstitu ted Al-
len es. When a p-xylene solution of 1,3-bis(methylseleno)-
allene 1 was refluxed for 3 d, (E)- and (Z)-1,3,4,6-

Synthesis and Reactivity of Allenes
J . Org. Chem., Vol. 66, No. 5, 2001 1789
Ta ble 1. Th er m a l Rea ction of Allen es 1, 2, a n d 3 in
Reflu xin g p-Xylen e
product (%)
reaction
allene
time
galvinoxyl conversion (%)
6
7
8
9
10 11
1
1
2
2
2
3
3 d
3 d
1.5 h
1.5 h
1.5 h
1.5 h
79
100
90
100
100
40
34
7
21
9
5 equiv
36
4
8
2
57 25
41
11
5 equiv
10 equiv
28
7
Sch em e 3
F igu r e 2. Crystal structure of 8 (one of unequivalent two
molecules) showing 50% probability displacement ellipsoids.
Selected bond lengths (Å), bond angles (deg), and torsion
angles (deg): C(1)-C(2), 1.368(6); C(1)-C(3), 1.492(6); C(1)-
C(7), 1.478(6); C(2)-C(4), 1.507(7); C(2)-C(8), 1.462(6); C(3)-
C(4), 1.537(6); C(3)-C(5), 1.344(6); C(4)-C(6), 1.334(6); C(2)-
C(1)-C(3), 93.4(4); C(2)-C(1)-C(7), 133.2(4); C(1)-C(2)-C(4),
92.8(4); C(1)-C(2)-C(8), 132.0(5); C(1)-C(3)-C(4), 86.9(4);
C(1)-C(3)-C(5), 131.7(4); C(2)-C(4)-C(3), 86.4(4); C(2)-
C(4)-C(6), 134.0(4); C(7)-C(1)-C(2)-C(8), -3.3(9); C(3)-
C(1)-C(2)-C(4), -5.3(4); C(1)-C(3)-C(4)-C(2), -4.7(3); C(5)-
C(3)-C(4)-C(6), -24(1).
ated disappearance of the allenes. This means the exist-
ence of reverse radical coupling reaction of allenyl radical
and selenenyl radical, formed by homolytic cleavage of
the carbon-selenium bond of the starting materials, to
give the allenes, and the acceleration of the disappear-
ance may be a result from the radical trapping by
galvinoxyl.
atoms, whereas the four-membered ring has almost
planar geometry {C(1)-C(3)-C(4)-C(2) ) 5°}. It was
also found that isomerization from Z-isomer 7 to E-isomer
6 occurred between enediynes 6 and 7 under the refluxing
conditions in p-xylene; ca. a 2:1 mixture of 6 and 7 was
obtained from 7 after 1.5 h.
The mechanism for the formation of enediynes 6 and
7 is considered as follows (Scheme 3). Homolytic cleavage
of the carbon-selenium bond of allene 1, 2, or 3 gives
radical 12 and the selenenyl radical. Dimerization of
radical 12 yields hexadiyne 13 followed by elimination
of diselenide to afford enediynes 6 and 7. In the case of
allene 1, addition between sp-hybridized carbons also
occurs to give biradical intermediate 14 followed by
intramolecular cyclization to form cycloadduct 15. Under
the conditions, further reaction occurs to give cyclobutene
derivatives 8 and 9 with extrusion of dimethyl diselenide.
The reason cyclobutene derivative was not obtained in
the case of allene 2 is maybe due to fast cleavage of the
carbon-selenium bond and/or repulsion between two
benzyl groups in formation of the carbon-carbon bond.
Another mechanism for formation of enediynes 6 and 7
is also plausible, that is, elimination of diselenide from
cyclobutene derivative 8 or 9. However, enediyne 6 or 7
was not obtained from isolated 8 under the conditions.
The thermal reactivity of cyclic monoallenes 4b and
4c was also investigated in p-xylene solution under
reflux. In the case of 4c, bicyclic compound 16 was
obtained in 59% yield, whereas the reaction of 4b was
intricate, and no identified compound was obtained
(Scheme 4). The structure of 16 was determined by X-ray
Thermal reaction of 1,3-bis(benzylseleno)allene 2 pro-
ceeded smoothly under similar conditions, and enediynes
6 and 7 were formed in 36% and 8% yields, respectively,
along with dibenzyl diselenide 10 (57%) and dibenzyl
selenide 11 (25%). In this reaction, cyclic compound
corresponding to 8 or 9 was not obtained. In the thermal
reaction of unsymmetric allene 3, the reaction was
intricate, and only enediynes 6 and 7 could be isolated
in 28% and 7% yields, respectively. The thermal reac-
tivities of selenium-substituted allenes 1 and 2 were
found to be different from those of the corresponding
sulfur-substituted allenes, i.e., thermal reactions which
afforded thiophene derivatives as major products.4 The
difference of the reactivities must be due to the smaller
bond dissociation energy of the carbon-selenium bond
than that of the carbon-sulfur bond. The formation of
the enediynes in the thermal reactions of 1 and 2 was
inhibited by addition of galvinoxyl (Table 1). Therefore,
the thermal reactions of the selenium-substituted allenes
to give the enediynes were found to proceed through
radical mechanism. Addition of galvinoxyl also acceler-

1790 J . Org. Chem., Vol. 66, No. 5, 2001
Shimizu et al.
Sch em e 4
of cyclic bisallenes dl- and meso-5a in a p-xylene solution
caused an intramolecular cyclization reaction and the
subsequent elimination of the SeCH2CH2Se moiety to
give bicyclic product 18 in 41% and 36% yields, respec-
tively, together with small amounts of enediynes 6 and
7, 1,2-diselenine 19, and cyclic diselenide 20. In these
reactions, meso-5a was also formed from dl-5a , and dl-
5a was formed from meso-5a . This observation indicates
that a reverse reaction is occurring from the common
intermediate to give the stereoisomer of dl- or meso-5a .
Therefore, bicyclic compound 18 is considered to be
formed via 2,2′-bisallyl biradical 21 followed by subse-
quent carbon-carbon bond formation and elimination of
the selenium substituent, as shown in Scheme 5. In the
case of corresponding tetrathiacyclic bisallenes, the sulfur
analogue corresponding to compound 22 was obtained
quantitatively.4 This difference may be explained by the
small bond dissociation energy of carbon-selenium bond.
Reverse reaction from 21 to the starting material may
yield dl- and meso-5a . Compound 19 will be formed from
18 with extrusion of ethylene under the conditions, since
isolated 18 gave compound 19 under the conditions
although the reaction was slow (8 h; 18% conversion, 88%
yield). Formation of cyclic monoallene 20 is also consid-
ered as a result of homolytic cleavage of the carbon-
selenium bond of the starting materials, and the subse-
quent reaction will form the enediynes.
Sch em e 5
F igu r e 3. Crystal structure of 16 (one of unequivalent two
molecules) showing 50% probability displacement ellipsoids.
Selected bond lengths (Å), bond angles (deg), and torsion
angles (deg): Se(1)-C(1), 1.908(6); Se(1)-C(4), 1.967(6); Se-
(2)-C(3), 2.019(7); Se(2)-C(7), 1.946(7); C(1)-C(2), 1.351(8);
C(1)-Se(1)-C(4), 96.2(2); C(3)-Se(2)-C(7), 91.3(3); Se(1)-
C(1)-C(2), 122.8(4); C(1)-C(2)-C(3), 130.2(5); Se(1)-C(1)-
C(2)-C(3), 7.0(8).
P h otoch em ica l Rea ction of Selen iu m -Su bstitu ted
Allen es. Irradiation of a benzene solution of allene 1 for
15 min through a Pyrex filter afforded enediynes 6 and
7 and 3,3-bis(methylseleno)-1,3-diphenylpropyne 23 in
14%, 11%, and 16% yields, respectively (Scheme 6). The
longer irradiation time (1 h) increased the formation of
enediynes 6 and 7 with decreasing rearrangement prod-
uct 23. Irradiation of 2 also yielded enediynes 6 and 7 in
yields of 22% and 16% together with 57% of dibenzyl
diselenide 10. In this reaction, 3,3-bis(benzylseleno)-1,3-
diphenylpropyne was not obtained unlike the sulfur
analogue, which has been obtained by irradiation of 1,3-
bis(benzylthio)-1,3-diphenylpropadiene.4 Lack of forma-
tion of the 1,3-diphenylpropyne in the reaction of 2 may
be due to further photochemical reaction of the propyne
to give the enediynes. No formation of enediynes 6 and
7 was found when allene 2 was irradiated under oxygen
bubbling, and 1,3-diphenylpropynone 24 was obtained in
63% yield. Irradiation of cyclic monoallenes 4b and 4c
also gave enediynes 6 and 7 along with rearrangement
compounds 25 and 26, respectively (Scheme 7). In the
case of 4b , longer irradiation time also increased the
analysis, and the stereochemical relationship between the
hydrogen and phenyl group at the bridge head was
determined to be syn geometry, as shown in Figure 3. In
this reaction, an intramolecular hydrogen-abstraction
reaction by sp-hybridized carbon from methylene may be
occurring at the initial stage to give biradical intermedi-
ate 17 and the subsequent intramolecular radical-
coupling reaction yields bicyclic compound 16. Heating

Synthesis and Reactivity of Allenes
J . Org. Chem., Vol. 66, No. 5, 2001 1791
allenes to give biradical 27, which yields carbene 28.9
Further rearrangement of the selenenyl group gives the
alkynes. The alkynes also react photochemically to give
a carbon radical by homolytic cleavage of carbon-
selenium bond. A radical-coupling reaction of the carbon
radical followed by subsequent elimination of diselenide
yields enediynes 6 and 7.
Sch em e 6
Con clu sion
1,3-Bis(methylseleno)-, 1,3-bis(benzylseleno)-, and 1-ben-
zylseleno-3-methylseleno-1,3-diphenylpropadienes were
synthesized by reaction of Ph2C3 dianion with dimethyl
diselenide and/or benzylselenocyanate. Diselenocyclic
allenes, a type of compounds which has not been obtained
in the case of corresponding sulfur analogue, and tetra-
selenocyclic bisallenes were also obtained by reacting the
dianion with alkane diselenocyanates. Thermal reaction
of the allenes afforded enediynes, which were not ob-
tained in the case of sulfur analogue, through a radical
pathway. Irradiation of allenes caused rearrangement of
the selenenyl group to give alkynes, and the alkynes also
reacted photochemically to yield the enediynes whereas
corresponding sulfur-substituted alkynes did not react
photochemically.
Sch em e 7
Exp er im en ta l Section
Gen er a l Meth od s. Tetrahydrofuran, n-hexane, and ben-
zene were distilled from sodium metal before use. p-Xylene
was freshly distilled from calcium hydride. Column chroma-
tography was performed with silica gel (70-230 mesh). Gel
permeation chromatography (GPC) was performed with two
J AIGEL-1H columns (20 mm × 600 mm), and the products
were eluted with chloroform. All reactions were carried out
under nitrogen.1H and 13C NMR spectra were measured with
Me4Si as internal standard.
Syn th esis of 1,3-Bis(m eth ylselen o)-1,3-d ip h en ylp r o-
p a d ien e (1). To a hexane solution (40 mL) of 1,3-diphenyl-
propyne10 (1.00 g, 5.21 mmol) was added dropwise n-butyl-
lithium (1.54 mol/L, 6.6 mL, 10.2 mmol) under nitrogen at
room temperature,11 and the solution was stirred for 1 h.
TMEDA (N,N,N′,N′-tetramethylethylenediamine) (0.80 mL,
5.32 mmol) was added to the mixture, and stirring was
continued for an additional 1 h. A benzene solution (20 mL)
of dimethyl diselenide (2.06 g, 11.0 mmol) was added dropwise
to the solution and stirred for 30 min. Water (100 mL) was
added to the solution, and the product was extracted with
benzene. The combined organic extracts were washed with
brine and dried over anhydrous magnesium sulfate. After
removal of the solvent in vacuo, the product was purified by
silica gel column chromatography (benzene/hexane ) 1/8) to
give allene 1 (1.36 g, 70%).
formation of enediynes 6 and 7 with decreasing rear-
rangement product 25, indicating the endiynes are
secondary products from the rearrangement product.
Irradiation of isolated 25 yielded enediynes 6 and 7 and
cyclic monoallene 4b in 18%, 16%, and 13% yields,
respectively, which confirms the hypothesis and also
indicates the existence of a photochemical reverse reac-
tion from 25 to cyclic monoallene 4b. Similarly, cyclic
bisallenes dl- and meso-5a were also irradiated and
afforded enediynes 6 and 7 together with cyclic monoal-
lene 20. In these reactions, meso-5a was also formed from
dl-5a , and dl-5a was formed from meso-5a .
1,3-Bis(m eth ylselen o)-1,3-d ip h en ylp r op a d ien e (1). Yel-
1
low liquid; H NMR (500 MHz, CDCl3) δ 2.14 (s, 6H), 7.26 (t,
2H, J ) 7.3 Hz), 7.33 (t, 4H, J ) 7.3 Hz), 7.53 (d, 4H, J ) 7.3
Hz); 13C NMR (125 MHz, CDCl3) δ 7.1, 106.9, 127.0, 128.2,
128.6, 135.2, 193.4; IR (neat) νmax 3052, 2926, 1906, 1595, 1491,
(9) (a) Steinmetz, M. G.; Mayes, R. T. J . Am. Chem. Soc. 1985, 107,
2111. (b) Stierman, T. J .; J ohnson, R P. J . Am. Chem. Soc. 1985, 107,
3971. (c) Stierman, T. J .; Shakespeare, W. C.; J ohnson, R P. J . Org.
Chem. 1990, 55, 1043.
(10) J acobs, T. L.; Dankner, D. J . Org. Chem. 1957, 22, 1424.
(11) (a) Klein, J .; Backer, J . Y. J . Chem. Soc., Chem. Commun. 1973,
576. (b) Leroux, Y.; Mantione, R. Tetrahedron Lett. 1971, 591.
In the photochemical reactions, the first step is pho-
torearrangement to give alkynes, such as 23, 25, and 26.
The photorearrangement may proceed via photoinduced
1,2-rearrangement of the alkylselenenyl group of the

1792 J . Org. Chem., Vol. 66, No. 5, 2001
Shimizu et al.
1444, 1420, 1273, 1211, 1029, 911, 857, 760, 690 cm-1; UV
(cyclohexane) λmax 205 (ꢀ 3.69 × 104), 236 (ꢀ 2.37 × 104), 250
(sh, ꢀ 2.14 × 104), 298 (ꢀ 1.54 × 104) nm; MS m/z 378 (M+,
prisms (meso-5a ) and yellow solid (dl-5a ). 5a , 26% (511 mg,
dl/ meso ≈ 1/2); 4b, 57% (1.16 g); 5b, 1% (29 mg, dl/ meso ≈
1/1).
5%), 285 (100%), 270 (14%), 189 (35%). Anal. Calcd for C17H16
Se2: C, 53.98; H, 4.26. Found: C, 54.27; H, 4.24.
-
1,3-Dip h en yl-4,8-d iselen ocycloocta -1,2-d ien e (4b). Mp
173.9-175.0 °C (orange needles from chloroform-hexane); 1H
NMR (500 MHz, CDCl3) δ 2.42-2.46 (m, 2H), 2.86-2.90 (m,
2H), 3.14-3.20 (m, 2H), 7.30 (tt, 2H, J ) 1.6, 7.2 Hz), 7.38 (t,
4H, J ) 7.2 Hz), 7.62 (dd, 4H, J ) 1.6, 7.2 Hz); 13C NMR (125
MHz, CDCl3) δ 24.8, 40.3, 108.3, 127.9, 128.5, 128.6, 135.0,
192.4; IR (KBr) νmax 3068, 3037, 2937, 1887, 1591, 1490, 1443,
1408, 1290, 855, 760, 689 cm-1; UV (cyclohexane) λmax 236 (ꢀ
2.05 × 104), 250 (ꢀ 2.16 × 104), 317 (ꢀ 1.22 × 104) nm; MS m/z
390 (M+, 8%), 349 (1%), 270 (60%), 190 (100%). Anal. Calcd
for C18H16Se2: C, 55.40; H, 4.13. Found: C, 55.38; H, 4.16.
d l-1,3,8,10-Tetr a p h en yl-4,7,11,14-tetr a selen ocyclotet-
r a d eca -1,2,8,9-tetr a en e (d l-5a ). Mp 168.8-170.5 °C (decomp,
Syn th esis of 1,3-Bis(ben zylselen o)-1,3-d ip h en ylp r op a -
d ien e (2). To a hexane solution (45 mL) of 1,3-diphenylpro-
pyne (1.50 g, 7.81 mmol) was added dropwise n-butyllithium
(1.54 mol/L, 10.0 mL, 15.4 mmol) under nitrogen at room
temperature, and the solution was stirred for 1 h. TMEDA
(1.20 mL, 7.98 mmol) was added to the mixture, and stirring
was continued for an additional 1 h. A benzene solution (45
mL) of benzylselenocyanate (3.34 g, 17.0 mmol) was added
dropwise at -20 °C to the solution and allowed to warm to
room temperature. Water (100 mL) was added to the solution,
and the product was extracted with benzene. The combined
organic extracts were washed with brine and dried over
anhydrous magnesium sulfate. After removal of solvent in
vacuo, the product was purified by silica gel column chroma-
tography (benzene/hexane ) 1/6) to give allene 2 (2.60 g, 64%).
1,3-Bis(ben zylselen o)-1,3-d ip h en ylp r op a d ien e (2). Mp
100.0-100.7 °C (pale yellow prisms from ethanol-hexane); 1H
NMR (500 MHz, CDCl3) δ 3.90 (s, 4H), 7.16-7.28 (m, 12H),
7.31 (t, 4H, J ) 7.7 Hz), 7.46 (d, 4H, J ) 7.7 Hz); 13C NMR
(125 MHz, CDCl3) δ 31.1, 103.3, 126.9, 127.4, 128.2, 128.5,
128.7, 129.1, 134.8, 138.0, 197.6; IR (KBr) νmax 3076, 3027,
1904, 1594, 1490, 1453, 1444, 1172, 1029, 912, 862, 761, 697,
629 cm-1; UV (cyclohexane) λmax 203 (ꢀ 5.77 × 104), 229 (sh, ꢀ
3.98 × 104), 266 (sh, ꢀ 2.35 × 104), 307 (ꢀ 1.38 × 104) nm; MS
m/z 530 (M+, 8%), 439 (100%), 359 (54%). Anal. Calcd for
1
yellow solid); H NMR (500 MHz, CDCl3) δ 3.35 (s, 8H), 7.26
(t, 4H, J ) 7.9 Hz), 7.33 (t, 8H, J ) 7.9 Hz), 7.52 (d, 8H, J )
7.9 Hz); 13C NMR (125 MHz, CDCl3) δ 26.7, 100.2, 127.6, 128.2,
128.7, 134.4, 199.3; IR (KBr) νmax 3020, 1903, 1593, 1488, 1444,
1159, 865, 757, 689, 640, 581 cm-1; UV (cyclohexane) λmax 208
(ꢀ 4.87 × 104), 236 (sh, ꢀ 4.19 × 104), 258 (ꢀ 4.35 × 104), 304
(sh, ꢀ 1.76 × 104) nm; MS m/z 724 (M+-2(CH2), 0.2%), 696
(0.2%), 617 (1%), 270 (78%), 190 (100%). Anal. Calcd for C34H28
Se4: C, 54.27; H, 3.75. Found: C, 54.13; H, 3.88.
-
meso-1,3,8,10-Tetr aph en yl-4,7,11,14-tetr aselen ocyclotet-
r a d eca -1,2,8,9-tetr a en e (m eso-5a ). Mp 159.0-160.0 °C (yel-
low prisms from chloroform-hexane); 1H NMR (500 MHz,
CDCl3) δ 3.10-3.24 (m, 8H), 7.26 (t, 4H, J ) 7.4 Hz), 7.32 (t,
8H, J ) 7.4 Hz), 7.49 (d, 8H, J ) 7.4 Hz); 13C NMR (125 MHz,
CDCl3) δ 26.3, 103.9, 127.3, 128.4, 128.7, 134.8, 196.3; IR (KBr)
νmax 3022, 1906, 1593, 1488, 1442, 1160, 864, 757, 694, 641,
619 cm-1; UV (cyclohexane) λmax 206 (ꢀ 7.19 × 104), 238 (ꢀ 4.57
× 104), 250 (sh, ꢀ 4.45 × 104), 303 (sh, ꢀ 1.95 × 104) nm; MS
m/z 696 (M+-4(CH2), 0.2%), 616 (0.7%), 536 (3%), 460 (11%),
380 (23%), 270 (79%), 190 (100%). Anal. Calcd for C34H28Se4:
C, 54.27; H, 3.75. Found: C, 54.32; H, 3.71.
1,3,9,11-Tet r a p h en yl-4,8,12,16-t et r a selen ocycloh exa -
d eca -1,2,9,10-tetr a en e (5b). As a dl/ meso mixture (≈1/1):
mp 98.5-112.5 °C (colorless solid); 1H NMR (500 MHz, CDCl3)
δ 2.08-2.26 (m, 4H), 2.76-2.92 (m, 8H), 7.23-7.33 (m, 12H),
7.49-7.53 (m, 8H); 13C NMR (125 MHz, CDCl3) δ 26.7, 27.2,
31.0, 31.3, 100.7, 103.1, 127.4, 127.5, 128.0, 128.1, 128.60,
128.64, 134.7, 134.9, 197.1, 198.4; IR (KBr) νmax 3051, 3022,
2920, 1903, 1593, 1489, 1443, 1210, 1074, 1028, 859, 757, 691,
639 cm-1; MS m/z 540 (M+-6(CH2)-2Se, 1%), 460 (2%), 380
(31%), 190 (100%). Anal. Calcd for C36H32Se4: C, 55.40; H, 4.13.
Found: C, 54.94; H, 4.27.
C
29H24Se2: C, 65.67; H, 4.56. Found: C, 65.79; H, 4.66.
Syn th esis of 1-Ben zylselen o-3-m eth ylselen o-1,3-d ip h e-
n ylp r op a d ien e (3). To a hexane solution (30 mL) of 1,3-
diphenylpropyne (1.00 g, 5.21 mmol) was added dropwise
n-butyllithium (1.54 mol/L, 6.6 mL, 10.2 mmol) under nitrogen
at room temperature, and the solution was stirred for 1 h.
TMEDA (0.80 mL, 5.32 mmol) was added to the mixture, and
stirring was continued for an additional 1 h. A benzene
solution (30 mL) of dimethyl diselenide (1.06 g, 5.63 mmol)
and benzylselenocyanate (1.23 g, 6.26 mmol) was added
dropwise to the solution and stirred for 30 min. Water (100
mL) was added to the solution, and the product was extracted
with benzene. The combined organic extracts were washed
with brine and dried over anhydrous magnesium sulfate. After
removal of solvent in vacuo, the product was purified by silica
gel column chromatography (benzene/hexane ) 1/8) to give
unsymmetric allene 3 (402 mg, 17%) together with symmetric
allenes 1 (520 mg, 26%) and 2 (128 mg, 5%).
1-Ben zylselen o-3-m et h ylselen o-1,3-d ip h en ylp r op a d i-
en e (3). Yellow liquid; H NMR (500 MHz, CDCl3) δ 2.06 (s,
Syn th esis of Diselen ocyclic Allen e (4c) a n d Tetr a se-
len ocyclic Bisa llen e (5c). To a hexane solution (60 mL) of
1,3-diphenylpropyne (1.50 g, 7.81 mmol) was added dropwise
n-butyllithium (1.57 mol/L, 10.0 mL, 15.7 mmol) under nitro-
gen at room temperature, and the solution was stirred for 1
h. TMEDA (1.20 mL, 7.98 mmol) was added to the mixture,
and stirring was continued for an additional 1 h. A benzene
solution (180 mL) of butane-1,4-diselenocyanate (2.35 g, 8.83
mmol) was added dropwise to the solution at -20 °C and
allowed to warm to room temperature. Stirring was continued
for an additional 1 d. Water (100 mL) was added to the
solution, and the products were extracted with THF. The
combined organic extracts were washed with brine and dried
over anhydrous magnesium sulfate. After removal of solvent
in vacuo, the product was purified by silica gel column
chromatography (benzene/hexane ) 1/5) to give cyclic allene
4c (442 mg, 14%) and cyclic bisallene 5c (447 mg, 14%) (dl/
meso ≈ 1/1). One stereoisomer of 5c was obtained by washing
the dl- and meso-mixture of 5c with chloroform.
1,3-Dip h en yl-4,9-d iselen ocyclon on a -1,2-d ien e (4c). Mp
136.5-137.8 °C (yellow needles from chloroform-hexane); 1H
NMR (500 MHz, CDCl3) δ 1.87-1.96 (m, 2H), 2.14-2.24 (m,
2H), 2.80-2.92 (m, 4H), 7.26 (t, 2H, J ) 8.3 Hz), 7.35 (t, 4H,
J ) 8.3 Hz), 7.65 (d, 4H, J ) 8.3 Hz); 13C NMR (125 MHz,
CDCl3) δ 26.5, 28.7, 99.1, 127.8, 128.0, 128.6, 134.8, 201.5; IR
(KBr) νmax 3052, 2926, 1947, 1591, 1492, 1487, 1441, 1264,
1072, 854, 758, 691 cm-1; UV (cyclohexane) λmax 228 (sh, ꢀ 2.18
1
3H), 3.97 (s, 2H), 7.14-7.35 (m, 11H), 7.45 (dd, 2H, J ) 1.5,
7.8 Hz), 7.54 (dd, 2H, J ) 1.2, 7.9 Hz); 13C NMR (125 MHz,
CDCl3) δ 7.2, 31.0, 105.2, 105.3, 126.9, 127.1, 127.2, 128.17,
128.20, 128.5, 128.6, 128.7, 129.1, 134.9, 135.0, 137.9, 195.3;
IR (neat) νmax 3057, 3027, 2925, 1906, 1594, 1490, 1445, 1029,
911, 860, 760, 692 cm-1; MS m/z 454 (M+, 2%), 361 (34%), 285
(100%), 269 (52%), 189 (69%). Anal. Calcd for C23H20Se2: C,
60.81; H, 4.44. Found: C, 60.90; H, 4.41.
Gen er a l P r oced u r e for th e Syn th esis of Diselen ocyclic
Allen e (4b) a n d Tetr a selen ocyclic Bisa llen es (5a a n d 5b).
To a hexane solution (40 mL) of 1,3-diphenylpropyne (1.00 g,
5.21 mmol) was added dropwise n-butyllithium (1.54 mol/L,
6.6 mL, 10.2 mmol) under nitrogen at room temperature, and
the solution was stirred for 1 h. TMEDA (0.80 mL, 5.32 mmol)
was added to the mixture, and stirring was continued for an
additional 1 h. A THF solution (120 mL) of alkane diseleno-
cyanate (1.1 equiv) was added dropwise to the solution at -80
°C, and the solution was allowed to warm to room temperature.
Stirring was continued for an additional 2 d. Water (100 mL)
was added to the solution, and the product was extracted with
benzene. The combined organic extracts were washed with
brine and dried over anhydrous magnesium sulfate. After
removal of solvent in vacuo, the products were separated by
gel permeation chromatography (chloroform). Compound 5a
was recrystallized from chloroform-hexane to give yellow

Synthesis and Reactivity of Allenes
J . Org. Chem., Vol. 66, No. 5, 2001 1793
× 104), 264 (ꢀ 2.38 × 104), 304 (sh, ꢀ 1.23 × 104) nm; MS m/z
404 (M+, 17%), 349 (21%), 270 (100%), 190 (80%). Anal. Calcd
for C19H18Se2: C, 56.45; H, 4.49. Found: C, 56.71; H, 4.50.
(100%), 269 (7%), 189 (36%). Anal. Calcd for C19H18Se2: C,
56.45; H, 4.49. Found: C, 56.44; H, 4.49.
2,7,9,10-Tet r a p h en yl-3,6-d iselen ob icyclo[6.2.0]d eca -
(Z,Z,Z)-1,7,9-tr ien e (18). Mp 196.0-197.0 °C (yellow solid);
1H NMR (500 MHz, CDCl3) δ 3.37 (s, 4H), 6.54 (d, 4H, J ) 7.6
Hz), 6.82 (t, 4H, J ) 7.6 Hz), 6.93-6.99 (m, 6H), 7.05 (t, 2H,
J ) 7.6 Hz), 7.26 (d, 4H, J ) 7.3 Hz); 13C NMR (125 MHz,
CDCl3) δ 30.7, 115.3, 126.9, 127.1, 127.3, 127.6, 127.9, 130.6,
131.8, 140.8, 145.3, 152.9; IR (KBr) νmax 3058, 2909, 1598,
1479, 1440, 1409, 1227, 1074, 1028, 882, 768, 756, 696, 677
cm-1; MS m/z 566 (M+, 26%), 540 (42%), 460 (100%), 380 (31%),
1,3,10,12-Tetr a p h en yl-4,9,13,18-tetr a selen ocycloocta -
d eca -1,2,10,11-tetr a en e (5c). As a dl/ meso mixture (≈ 1/1):
mp 144.9-172.0 °C (colorless solid); 1H NMR (500 MHz,
CDCl3) δ 1.84-1.92 (m, 8H), 2.72-2.86 (m, 8H), 7.23-7.35 (m,
12H), 7.50-7.54 (m, 8H); 13C NMR (125 MHz, CDCl3) δ 26.6,
26.8, 30.0, 30.2, 103.0, 103.8, 127.1, 127.2, 128.08, 128.14,
128.6 (duplicate), 135.0 (duplicate), 196.3, 196.9; IR (KBr) νmax
3051, 3022, 2925, 1901, 1593, 1489, 1443, 1172, 1076, 1027,
865, 761, 691, 640 cm-1; MS m/z 540 (M+-8(CH2)-2Se, 1%), 460
(3%), 380 (35%), 190 (100%). Anal. Calcd for C38H36Se4: C,
56.45; H, 4.49. Found: C, 55.94; H, 4.47. One stereoisomer of
302 (31%); HRMS calcd for
568.0203.
C
32H2480Se2 568.0208, found
2,5,7,8-Te t r a p h e n yl-3,4-d ise le n ob icyclo[4.2.0]oct a -
1
(Z,Z,Z)-1,5,7-tr ien e (19). Mp 196.0-196.5 °C (red needles
5c: mp 170.2-171.9 °C (colorless solid); H NMR (500 MHz,
1
from chloroform-hexane); H NMR (500 MHz, CDCl3) δ 6.94
CDCl3) δ 1.83-1.93 (m, 8H), 2.72-2.87 (m, 8H), 7.26 (t, 4H, J
) 7.9 Hz), 7.33 (t, 8H, J ) 7.9 Hz), 7.53 (d, 8H, J ) 7.9 Hz);
13C NMR (125 MHz, CDCl3) δ 26.8, 30.2, 103.0, 127.3, 128.1,
128.6, 135.1, 197.0; IR (KBr) νmax 3055, 3027, 2940, 1909, 1593,
1490, 1444, 1173, 1075, 1027, 865, 761, 690, 640 cm-1; MS m/z
596 (M+- 4(CH2) - 2Se, 0.3%), 460 (5%), 380 (32%), 302 (3%),
190 (100%).
(d, 4H, J ) 7.7 Hz), 7.01 (t, 4H, J ) 7.7 Hz), 7.11-7.14 (m,
6H), 7.22 (t, 2H, J ) 7.7 Hz), 7.29 (d, 4H, J ) 7.5 Hz); 13C
NMR (125 MHz, CDCl3) δ 105.8, 127.6, 127.9, 128.0, 128.3,
128.6, 130.2, 131.6, 135.6, 136.8, 145.8; IR (KBr) νmax 3046,
1486, 1439, 1066, 1027, 767, 758, 694, 538 cm-1; MS m/z 538
(M+, 100%), 460 (30%), 380 (23%), 302 (63%). Anal. Calcd for
C
30H20Se2: C, 66.92; H, 3.74. Found: C, 66.87; H, 3.85.
Gen er a l P r oced u r e for th e Th er m a l Rea ction of Se-
len iu m -Su bstitu ted Allen es. A p-xylene solution (20 mL)
of selenium-substituted allene (1.0 mmol) was refluxed for a
desired period under nitrogen. After removal of solvent in
vacuo, the residue was subjected to silica gel column chroma-
tography (benzene/hexane). 1: 79% conversion (3 d), 66,12
(34%), 76,12 (7%), 8 (21%), 9 (9%). 2: 90% conversion (1.5 h), 6
(36%), 7 (8%), 1013 (57%), 1113 (25%). 3: 40% conversion (1.5
h), 6 (28%), 7 (7%). 4c: 34% conversion (55 h), 16 (59%). dl-
5a : 96% conversion (8 h), 6 (3%), 7 (1%), 18 (41%), 19 (11%),
20 (6%), meso-5a (10%). meso-5a : 84% conversion (8 h), 6 (5%),
7 (3%), 18 (36%), 19 (4%), 20 (7%), dl-5a (7%).
1,3-Dip h en yl-4,7,8,11-t et r a selen ocyclou n d eca -1,2-d i-
en e (20). Mp 112.3-114.2 °C (yellow solid); 1H NMR (500
MHz, CDCl3) δ 3.07-3.12 (m, 2H), 3.24-3.37 (m, 4H), 3.53-
3.58 (m, 2H), 7.27 (t, 2H, J ) 7.0 Hz), 7.35 (t, 4H, J ) 7.0 Hz),
7.53 (d, 4H, J ) 7.0 Hz); 13C NMR (125 MHz, CDCl3) δ 27.8,
31.9, 102.3, 127.8, 128.3, 128.7, 134.6, 198.1; IR (KBr) νmax
3055, 3019, 2916, 1904, 1594, 1489, 1444, 1408, 1231, 1158,
1075, 1029, 858, 755, 693 cm-1; MS m/z 562 (M+, 7%), 378 (8%),
80
350 (23%), 270 (87%), 189 (100%); HRMS calcd for C19H18
Se4 565.8069, found 565.8106.
-
Gen er a l P r oced u r e for th e P h otoch em ica l Rea ction
of Selen iu m -Su bstitu ted Allen es. A benzene solution (100
mL) of selenium-substituted allene (0.4 mmol) was irradiated
with a 450 W medium-pressure mercury lamp through a Pyrex
filter under argon for a desired period. After removal of solvent
in vacuo, the residue was subjected to gel-permeation chro-
matography (chloroform) or silica gel column chromatography
(benzene/hexane). 1: 82% conversion (1 h), 6 (20%), 7 (20%),
23 (10%). 2: 79% conversion (1 h), 6 (22%), 7 (16%), 10 (57%).
4b: 95% conversion (1 h), 6 (29%), 7 (23%), 25 (8%). 4c: 69%
conversion (1 h), 6 (8%), 7 (7%), 26 (51%). dl-5a : 86%
conversion (100 min), 6 (19%), 7 (16%), 20 (11%), meso-5a (8%).
meso-5a : 96% conversion (90 min), 6 (18%), 7 (17%), 20 (15%),
dl-5a (9%).
(Z,Z)-3,4-Bis{r-(m eth ylselen o)ben zylid en e}-1,2-d ip h e-
n ylcyclobu ten e (8). Mp 153.6-155.0 °C (yellow needles from
1
chloroform-methanol); H NMR (500 MHz, CDCl3) δ 1.70 (s,
6H), 6.64 (dd, 4H, J ) 1.2, 7.9 Hz), 6.81 (t, 4H, J ) 7.9 Hz),
6.90-6.96 (m, 8H), 7.10 (dd, 4H, J ) 1.2, 7.7 Hz); 13C NMR
(125 MHz, CDCl3) δ 8.9, 114.8, 126.66, 126.72, 127.1, 127.2,
127.8, 130.3, 131.9, 138.4, 142.2, 151.6; IR (KBr) νmax 3050,
2920, 1600, 1480, 1440, 1410, 1260, 1070, 1025, 910, 770, 700
cm-1; MS m/z 568 (M+, 26%), 475 (100%), 460 (33%), 380 (97%).
Anal. Calcd for C32H26Se2: C, 67.61; H, 4.61. Found: C, 67.38;
H, 4.71.
(E,Z)-3,4-Bis{r-(m eth ylselen o)ben zylid en e}-1,2-d ip h e-
n ylcyclobu t en e (9). Mp 112.1-113.8 °C (yellow solid); 1H
NMR (500 MHz, CDCl3) δ 1.26 (s, 3H), 1.53 (s, 3H), 6.59 (dd,
2H, J ) 1.1, 7.9 Hz), 6.80 (t, 2H, J ) 7.9 Hz), 6.87-6.97 (m,
6H), 7.27-7.34 (m, 4H), 7.41-7.45 (m, 4H), 7.54 (dd, 2H, J )
1.2, 8.3 Hz); 13C NMR (125 MHz, CDCl3) δ 7.4, 7.8, 116.9,
117.8, 126.6, 126.7, 127.1, 127.2, 127.4, 127.6, 127.7, 127.8,
128.6, 129.1, 130.3, 131.1, 131.9, 133.1, 138.3, 139.7, 140.3,
141.3, 152.5, 152.9; IR (KBr) νmax 3076, 3017, 2999, 1595, 1489,
1442, 1305, 1160, 1070, 1028, 923, 772, 755, 727, 699, 685
cm-1; MS m/z 568 (M+, 4%), 475 (100%), 460 (25%), 380 (85%).
Anal. Calcd for C32H26Se2: C, 67.61; H, 4.61. Found: C, 67.58;
H, 4.64.
cis-1,3-Dip h e n yl-4,9-d ise le n ob icyclo[4.3.0]n on a -2-
en e (16). Mp 92.5-93.5 °C (pale yellow plates from benzene-
hexane); 1H NMR (500 MHz, CDCl3) δ 2.46-2.57 (m, 3H), 2.73
(dd, 1H, J ) 4.2, 12.1 Hz), 2.93 (dd, 1H, J ) 2.2, 12.1 Hz),
3.23-3.28 (m, 1H), 3.38-3.44 (m, 1H), 6.58 (s, 1H), 7.21 (tt,
1H, J ) 1.5, 7.6 Hz), 7.28-7.32 (m, 3H), 7.36 (t, 2H, J ) 7.3
Hz), 7.54 (d, 2H, J ) 7.3 Hz), 7.70 (dd, 2H, J ) 1.5, 7.6 Hz);
13C NMR (125 MHz, CDCl3) δ 19.9, 23.4, 36.7, 49.8, 60.9, 125.1,
126.7, 126.9, 128.0, 128.3, 128.5, 128.7, 129.1, 140.8, 144.8;
IR (KBr) νmax 3050, 2949, 1595, 1487, 1442, 1279, 964, 758,
747, 733, 704, 693 cm-1; MS m/z 404 (M+, 11%), 351 (6%), 297
3,3-Bis(m eth ylselen o)-1,3-d ip h en ylp r op yn e (23). Mp
98.5-101.0 °C (pale yellow solid); 1H NMR (500 MHz, CDCl3)
δ 2.26 (s, 6H), 7.26 (t, 1H, J ) 7.4 Hz), 7.33-7.56 (m, 7H),
7.89 (d, 2H, J ) 7.4 Hz); 13C NMR (125 MHz, CDCl3) δ 9.7,
34.0, 88.5, 89.8, 122.7, 127.2, 127.8, 128.3, 128.4, 128.5, 131.8,
141.4; IR (KBr) νmax 3050, 3011, 2913, 1594, 1489, 1445, 1269,
1031, 910, 758, 699, 691, 520 cm-1; UV (cyclohexane) λmax 250
(ꢀ 4.41 × 103), 302 (sh, ꢀ 7.20 × 102) nm; MS m/z 378 (M+,
5%), 285 (100%), 270 (44%), 189 (50%); HRMS calcd for
C
17H1680Se2 379.9582, found 379.9626.
2-P h en eth yn yl-2-p h en yl-1,3-d iselen a n e (25). Pale yel-
1
low liquid; H NMR (500 MHz, CDCl3) δ 2.10-2.22 (m, 1H),
2.29-2.36 (m, 1H), 3.07-3.12 (m, 2H), 3.73 (dt, 2H, J ) 2.2,
13.3 Hz), 7.30-7.42 (m, 6H), 7.56-7.58 (m, 2H), 7.98 (dd, 2H,
J ) 1.2, 8.2 Hz); 13C NMR (125 MHz, CDCl3) δ 25.3, 26.4, 26.7,
89.2, 91.4, 122.9, 127.1, 128.4, 128.45, 128.47, 128.7, 131.7,
140.6; IR (neat) νmax 3056, 2915, 1596, 1489, 1446, 1242, 1030,
859, 756, 691 cm-1; UV (cyclohexane) λmax 224 (ꢀ 2.13 × 104),
251 (ꢀ 2.32 × 104) nm; MS m/z 390 (M+, 2%), 270 (21%), 190
(100%); HRMS calcd for C18H1680Se2 391.9582, found 391.9566.
2-P h en eth yn yl-2-ph en yl-1,3-diselen epa n e (26). Pale yel-
1
low liquid; H NMR (500 MHz, CDCl3) δ 2.35-2.50 (m, 4H),
3.18-3.28 (m, 2H), 3.35-3.45 (m, 2H), 7.28 (t, 1H, J ) 7.4
Hz), 7.34-7.38 (m, 5H), 7.54-7.57 (m, 2H), 7.98 (dd, 2H, J )
1.1, 8.4 Hz); 13C NMR (125 MHz, CDCl3) δ 27.0, 31.3, 35.4,
90.1, 91.4, 122.9, 126.8, 128.1, 128.3, 128.5 (duplicate), 131.7,
141.4; IR (neat) νmax 3055, 2919, 2847, 1596, 1489, 1443, 1261,
1030, 757, 694 cm-1; MS m/z 404 (M+, 4%), 351 (15%), 270
(12) Isagawa, K.; Mizuno, K.; Majima, T. Tetrahedron Lett. 1999,
40, 9051.
(13) Painter, E. P.; Franke, K. W.; Gortner, R. A. J . Org. Chem. 1940,
5, 579.

1794 J . Org. Chem., Vol. 66, No. 5, 2001
Shimizu et al.
(69%), 189 (100%); HRMS calcd for C19H1880Se2 405.9739, found
) 1.607 g cm-3. Of the 7560 unique data, 4454 with I > 2σ(I)
were used in the least-squares refinement to yield R1 ) 0.044
(R ) 0.114 and Rw ) 0.133 for all data).
405.9777. Anal. Calcd for
Found: C, 55.88; H, 4.27.
C19H18Se2: C, 56.45; H, 4.49.
X-r a y An a lysis: Com p ou n d 4b. Orange needle of C18H16
-
Se2 having approximate dimensions of 0.80 × 0.80 × 0.75 mm3.
Monoclinic space group P21/n with a ) 17.438 (9) Å, b ) 8.90
(1) Å, c ) 10.622 (6) Å, â ) 105.424 (2)°, V ) 1588 (2) Å3, Z )
4, and F(calcd) ) 1.632 g cm-3. Of the 7281 unique data, 4486
with I > 2σ(I) were used in the least-squares refinement to
yield R1 ) 0.050 (R ) 0.121 and Rw ) 0.129 for all data).
Com p ou n d 8. Yellow needle of C32H26Se2 having approximate
dimensions of 0.30 × 0.20 × 0.30 mm3. Monoclinic space group
P2/c with a ) 18.6330 (9) Å, b ) 10.3138 (5) Å, c ) 27.749 (2)
Å, â ) 100.364 (2)°, V ) 5245.7 (4) Å3, Z ) 8, and F(calcd) )
1.440 g cm-3. Of the 11 951 unique data, 4872 with I > 2σ(I)
were used in the least-squares refinement to yield R1 ) 0.048
(R ) 0.096 and Rw ) 0.120 for all data). Com p ou n d 16. Pale
yellow plate of C38H36Se4 having approximate dimensions of
0.80 × 0.70 × 0.55 mm3. Triclinic space group P1 bar with a )
10.19 (3) Å, b ) 8.17 (3) Å, c ) 20.2 (1) Å, R ) 89.5 (4)°, â )
97.7 (3)°, γ ) 90.1 (3)°, V ) 1670 (11) Å3, Z ) 2, and F(calcd)
Ack n ow led gm en t. This work was financially sup-
ported in part by a Grant-in-Aid for Scientific Research
from the Ministry of Education, Science, Sports, and
Culture, J apan. The authors thank Prof. H. Matsuzaka
(Tokyo Metropolitan University) for help with X-ray
analysis.
Su p p or tin g In for m a tion Ava ila ble: Detailed informa-
tion of the X-ray crystallographic analysis of 4b, 8, and 16
including structure diagram, details of data collection and
reduction and structure solution and refinement, tables of
positional and thermal parameters, and bond lengths, angles,
and torsional angles. This information is available free of
charge via the Internet at http://pubs.acs.org.
J O001483S