Synthesis and thermal reaction of 1,3-bis(alkylseleno)allenes

Article abstract of DOI:10.1021/ol0001158

(Equation presented) Reactions of Ph₂C₃ dianion, prepared from 1,3-diphenylpropyne and n-butyllithium, with dimethyl diselenide and benzylselenocyanate yielded 1,3-bis(methylseleno)-1,3-diphenylpropadiene and 1,3-bis(benzylseleno)-1,

Full text of DOI:10.1021/ol0001158

ORGANIC
LETTERS
2000
Vol. 2, No. 13
1923-1925
Synthesis and Thermal Reaction of
1,3-Bis(alkylseleno)allenes
Toshio Shimizu, Daisuke Miyasaka, and Nobumasa Kamigata*
Department of Chemistry, Graduate School of Science, Tokyo Metropolitan UniVersity,
Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan
kamigata-nobumasa@c.metro-u.ac.jp
Received April 28, 2000
ABSTRACT
Reactions of Ph2C dianion, prepared from 1,3-diphenylpropyne and n-butyllithium, with dimethyl diselenide and benzylselenocyanate yielded
3
1,3-bis(methylseleno)-1,3-diphenylpropadiene and 1,3-bis(benzylseleno)-1,3-diphenylpropadiene, respectively, and the reaction with a mixture
of dimethyl diselenide and benzylselenocyanate gave 1-benzylseleno-3-methylseleno-1,3-diphenylpropadiene together with the symmetric products.
Thermal reactions of the 1,3-bis(alkylseleno)allenes afforded (E)- and (Z)-1,3,4,6-tetraphenyl-3-hexene-1,5-diynes along with compounds derived
from cyclic dimer of the allene or diselenide via radical pathway.
Allene chemistry has been widely studied,1,2 and substituted
allenes by heteroatoms have also received attention.2 Re-
cently, we reported the synthesis and reaction of sulfur-
substituted allenes, and the thermal reactions of 1,3-bis-
(alkylthio)allenes have been found to yield thiophene
derivatives.3 Several selenium-substituted allenes are also
known as isolable compounds or reactive intermediates.4 We
also synthesized the 1,3-bis(alkylseleno)allenes, and it was
found that thermal reactions of the selenium-substituted
allenes are different from those of corresponding sulfur-
substituted allenes and afforded enediyne derivatives. In this
paper, we report the synthesis and thermal reaction of 1,3-
bis(alkylseleno)allenes.
When a benzene solution of 2 equiv of dimethyl diselenide
was added dropwise to Ph2C3 dianion (1,3-dilithioallene),
prepared5 from 1,3-diphenylpropyne and n-butyllithium in
hexane solution, in the presence of TMEDA (N,N,N′,N′-
tetramethylethylenediamine), and the solution was stirred for
additional 30 min, 1,3-bis(methylseleno)-1,3-diphenylpro-
padiene (16) was obtained in 70% yield after purification by
column chromatography on silica gel (Scheme 1). TMEDA
Scheme 1
* To whom correspondence should be addressed. Tel: +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.
(3) (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.
10.1021/ol0001158 CCC: $19.00 © 2000 American Chemical Society
Published on Web 06/03/2000

was found to be indispensable to this reaction, and the yield
was lowered (22%) when the reaction was carried out without
TMEDA. Similarly, reaction of the dianion with 2 equiv of
benzylselenocyanate in the presence of TMEDA yielded 1,3-
bis(benzylseleno)-1,3-diphenylpropadiene (26) in 64% yield.
Reaction of the dianion with a mixture of dimethyl diselenide
and benzylselenocyanate afforded unsymmetric allene 36 in
17% yield together with symmetric allenes 1 (26%) and 2
(5%). 3,3-Bis(alkylseleno)-1,3-diphenylpropyne, which has
possibility to form in these reactions, was not detected in
all the cases. Methyl signals of 1 was observed at higher
fields (1H: δ 2.14; 13C: δ 7.1) than those of corresponding
spectral properties.11 The structure of enediynes 4 and 5 was
confirmed by X-ray analysis of E-isomer 4 (Figure 1).12 It
1
sulfur analogue (1H: δ 2.24; 13C: δ 15.6)3 on the H and
13C NMR spectra in CDCl3, and absorption maxima of 1
and 2 were observed at 298 and 307 nm in cyclohexane,
respectively, which are shifted to longer wavelengths com-
pared with those of the corresponding sulfur analogues.
1,3-Bis(methylseleno)allene 1 reacted in refluxing p-xylene
to give (E)- and (Z)-1,3,4,6-tetraphenyl-3-hexene-1,5-diynes
(47 and 58), the framework of which is known as an important
building block of several naturally occurring antitumor
antibiotics9 and as a substrate of the Masamune-Bergman
reaction,10 (Z,Z)-1,2-bis(R-(methylseleno)benzylidene)-3,4-
diphenylcyclobutene (66), and the E,Z-isomer 76 in yields
of 34, 7, 21, and 9%, respectively, after 3 d (Scheme 2).
Figure 1. Crystal structure of 4 showing 50% probability displace-
ment ellipsoids.
was also found that Z-E isomerization occurred between 4
and 5 under the conditions, and ca. 2:1 mixture of 4 and 5
was obtained from 5 in a refluxing p-xylene after 1.5 h.
Scheme 2
(5) (a) Klein, J.; Backer, J. Y. J. Chem. Soc., Chem. Commun. 1973,
576. (b) Leroux, Y.; Mantione, R. Tetrahedron Lett. 1971, 591.
(6) All new compounds gave satisfactory elemental analysis, and IR,
NMR, and mass spectral data correlated with the assigned structures.
(7) 4: Mp 156.2-157.2 °C (pale yellow prisms from benzene/hexane);
1H NMR (500 MHz, CDCl3) δ 7.27-7.31 (m, 10H), 7.39 (t, 2H, J ) 7.30
Hz), 7.46 (t, 4H, J ) 7.30 Hz), 7.98 (d, 4H, J ) 7.30 Hz); 13C NMR (125
MHz, CDCl3) δ 90.9, 98.6, 123.2, 127.8, 128.3 (duplicate), 128.4, 128.6,
129.2, 131.4, 139.0; IR (KBr) νmax 3097, 3025, 1600, 1500, 1450, 1320,
1240, 1180, 1040, 780, 760, 740, 692 cm-1; UV (cyclohexane) λmax 269 (ꢀ
3.16 × 104), 367 (ꢀ 3.30 × 104) nm; MS (m/z) 380 (M+), 302. Anal. Calcd
for C30H20: C, 94.70; H, 5.30. Found: C, 94.82; H, 5.41.
(8) 5: Mp 105.0-106.1 °C (pale yellow needles from benzene/hexane);
1H NMR (500 MHz, CDCl3) δ 7.20-7.23 (m, 6H), 7.30-7.35 (m, 10H),
7.54-7.56 (m, 4H); 13C NMR (125 MHz, CDCl3) δ 91.8, 96.8, 123.4, 127.8,
128.0, 128.4, 128.5, 129.2, 129.7, 131.6, 137.5; IR (KBr) νmax 3050, 3017,
2926, 1597, 1486, 1441, 1415, 1266, 1029, 909, 766, 756, 698 cm-1; UV
(cyclohexane) λmax 269 (ꢀ 2.55 × 104), 361 (ꢀ 2.00 × 104) nm; MS (m/z)
380 (M+), 302, 189. Anal. Calcd for C30H20: C, 94.70; H, 5.30. Found: C,
94.96; H, 5.55.
(9) (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.; Chen, X.; Lau, K. Y.; Batac, I. V.;
Tuveson, R. W.; Hudson, J. B. J. Photochem. Photobiol. B: Biol. 1993,
21, 135. (i) Wender, P. A.; Zercher, C. K.; Beckham, S.; Haubold, E.-M.
J. Org. Chem. 1993, 58, 5867.
Enediynes 4 and 5 have recently synthesized, and assignment
of the E- and Z-isomers was made on the basis of their
(10) (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) Jones,
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.; Jagadeesh, M. N.; Chandrasekhar, J. J. Org. Chem.
1996, 61, 2247. (g) Evenzahav, A.; Turro, N. J. J. Am. Chem. Soc. 1998,
120, 1835.
(4) (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. USSR 1973, 9, 683. (c) Braverman, S.; Duar, Y. Tetrahedron Lett.
1978, 1493. (d) Braverman, S.; Freund, M.; Goldberg, I. Tetrahedron 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.
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1995, 68, 3221.
1924
Org. Lett., Vol. 2, No. 13, 2000

Scheme 3
enediyne compounds 4 and 5. In the case of allene 1, addition
Thermal reaction of 1,3-bis(benzylseleno)allene 2 proceeded
smoothly in a refluxing p-xylene, and enediynes 4 and 5 were
formed in 36 and 8% yields, respectively, together with
dibenzyl diselenide 8 (57%) and dibenzyl selenide 9 (25%)
after 1.5 h. In the thermal reaction of unsymmetric allene 3,
the reaction was intricate, and only enediyne compounds 4
(28%) and 5 (7%) were isolated. The thermal reactivities of
selenium-substituted allenes 1 and 2 were found to be
different from those of the corresponding sulfur-substituted
allenes,3 and the difference of the reactivities may be due to
smaller bond dissociation energy of carbon-selenium bond
than that of carbon-sulfur bond. The thermal reactions of
sulfur-substituted allenes 1, 2, and 3 were found to proceed
via radical mechanism since an addition of galvinoxyl in the
reaction of 1 and 2 inhibited both reactions.
between sp-hybridized carbons also occurs to give biradical
intermediate 12 followed by intramolecular cyclization to
form cycloadduct 13. Under the conditions, further reaction
occurs to give cyclobutene derivatives 6 and 7 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.
Acknowledgment. The present study was financially
supported in part by a Grant-in-Aid for Scientific Research
from the Ministry of Education, Science, Sports, and Culture,
Japan.
One plausible mechanism is shown in Scheme 3. Ho-
molytic cleavage of the carbon-selenium bond of allenes
1, 2, and 3 gives radical 10 with extrusion of seleno radical.
An attack of the seleno radical to the selenium atom of 10
yields carbene 11 followed by dimerization of 11 to afford
Supporting Information Available: Detailed information
of the X-ray crystallographic analysis of 4 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.
Detailed experimental procedures and spectral data including
1H and 13C NMR, IR, and mass spectra, and elemental
analysis of 1, 2, 3, 6, and 7.
(11) Isagawa, K.; Mizuno, K.; Majima, T. Tetrahedron Lett. 1999, 40,
9051.
(12) Crystal structure analysis for 4: formula C30H20, Mr ) 380.48,
crystal dimensions 0.20 × 0.20 × 0.20 mm, a ) 9.150(2), b ) 9.118(2),
c ) 12.576(1) Å, â ) 91.25(2)°, V ) 1035.8(3) Å3, Fcalct ) 1.220 g cm-3
,
Z ) 2, monoclinic, space group P21/n (No. 14), Rigaku AFC7R diffrac-
tometer, λ ) 0.71069 Å, T ) 296 K, 2667 measured reflections, 2520
unique, R ) 0.039, Rw ) 0.037.
OL0001158
Org. Lett., Vol. 2, No. 13, 2000
1925