ORGANIC
LETTERS
2
006
Vol. 8, No. 3
83-485
Nickel-Catalyzed Reactions of
Silacyclobutanes with Aldehydes: Ring
Opening and Ring Expansion Reaction
4
Koji Hirano, Hideki Yorimitsu,* and Koichiro Oshima*
Department of Material Chemistry, Graduate School of Engineering, Kyoto UniVersity,
Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
yori@orgrxn.mbox.media.kyoto-u.ac.jp; oshima@orgrxn.mbox.media.kyoto-u.ac.jp
Received November 14, 2005
ABSTRACT
The nickel-catalyzed ring opening reaction of silacyclobutanes with aldehydes affords the corresponding alkoxyallylsilanes. In contrast, the
ring expansion reaction of benzosilacyclobutene with aldehydes occurs under nickel catalysis to give oxasilacyclohexenes.
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Silacyclobutanes are an interesting class of compounds that
have unique reactivity due to their ring strain and Lewis
acid halides. However, nickel-catalyzed reactions of sila-
cyclobutanes have not been explored, although nickel belongs
to the same group, group 10. In this communication, we
describe the transformations of silacyclobutanes under nickel
catalysis.
1
2
3
acidity. Therefore, our group and others have developed
their synthetic utilities. Among them, palladium and platinum
complexes are known to catalyze quite useful transformations
4
including ring opening polymerization, cycloaddition with
Treatment of 1,1-dimethylsilacyclobutane (1a, 0.5 mmol)
with benzaldehyde (2a, 0.6 mmol) in the presence of 5 mol
5
alkynes and allenes, and coupling reactions with aryl and
%
2 6 11 3
of Ni(cod) and 10 mol % of P(c-C H ) in toluene (5
mL) at 100 °C for 12 h afforded allylbenzyloxydimethylsi-
lane (3a) in 20% yield (Table 1, entry 1). Apparently, a
carbon-silicon bond cleavage was involved in this trans-
formation, albeit the yield was low. We then screened various
ligands (Table 1). Although a number of phosphine ligands
(
1) Gordon, M. S.; Boatz, J. A.; Walsh, R. J. Phys. Chem. 1989, 93,
584-1585.
2) (a) Matsumoto, K.; Oshima, K.; Utimoto, K. Tetrahedron Lett. 1990,
1, 6055-6058. (b) Matsumoto, K.; Miura, K.; Oshima, K.; Utimoto, K.
7
1
(
3
Tetrahedron Lett. 1991, 32, 6383-6386. (c) Matsumoto, K.; Miura, K.;
Oshima, K.; Utimoto, K. Tetrahedron Lett. 1992, 33, 7031-7034. (d)
Matsumoto, K.; Yokoo, T.; Oshima, K.; Utimoto, K.; Rahman, N. A. Bull.
Chem. Soc. Jpn. 1994, 67, 1694-1700. (e) Matsumoto, K.; Oshima, K.;
Utimoto, K. J. Org. Chem. 1994, 59, 7152-7155. (f) Okada, K.; Matsumoto,
K.; Oshima, K.; Utimoto, K. Tetrahedron Lett. 1995, 36, 8067-8070.
have poor to moderate activity for this reaction, PPh
P(n-Bu) showed high efficiency (entries 3 and 7). Finally,
we found that the desired product was obtained in 88% yield
with 10 mol % of Ni(cod) and 20 mol % of PPh Me in
2
Me and
3
(3) (a) Denmark, S. E.; Griedel, B. D.; Coe, D. E.; Schnute, M. E. J.
Am. Chem. Soc. 1994, 116, 7026-7043. (b) Sunderhaus, J. D.; Lam, H.;
2
2
Dudley, B. Org. Lett. 2003, 5, 4571-4573.
toluene (5 mL) at 100 °C (entry 10). This reaction is regarded
as a hydrosilane-free reductive silylation of aldehydes.
(
4) (a) Weyenberg, D. R.; Nelson, L. E. J. Org. Chem. 1965, 30, 2618-
2
1
621. (b) Cundy, C. S.; Eaborn, C.; Lappert, M. F. J. Organomet. Chem.
972, 44, 291-297 and references cited therein. (c) Ushakov, N. V.; Vdovin,
V. M.; Pozdnyakova, M. V.; Pritula, N. A. IzV. Akad. Nauk. SSSR. Ser.
(6) (a) Tanaka, Y.; Yamashita, H.; Tanaka, M. Organometallics 1996,
15, 1524-1526. (b) Bhanu, P. S. C.; Tanaka, Y.; Yamashita, H.; Tanaka,
M. Chem. Commun. 1996, 1207-1208. (c) Tanaka, Y.; Nishigaki, A.;
Kimura, Y.; Yamashita, M. Appl. Organomet. Chem. 2001, 15, 667-670.
(7) NiCl2 and Ni(acac)2 did not catalyze the reaction.
Khim. 1983, 2125-2129.
(
5) (a) Sakurai, H.; Imai, T. Chem. Lett. 1975, 891-894. (b) Takeyama,
Y.; Nozaki, K.; Matsumoto, K.; Oshima, K.; Utimoto, K. Bull. Chem. Soc.
Jpn. 1991, 64, 1461-1466.
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0.1021/ol0527577 CCC: $33.50
© 2006 American Chemical Society
Published on Web 01/12/2006