Chemistry Letters Vol.32, No.1 (2003)
25
Table 1. Catalytic Activity of Several Ruthenium and Other Transition-Metal Complexesa
Run
Catalyst
Conv. of 1a/%b
Yield of 2a/%b
1
RuCl2(PPh3)3
95
75
2
—
7
0
3
4
5
RuCl3ÁnH2O
100
100
100
100
95
94
93
100
38
65
75
71
76
77
68
75
RuCl3ÁnH2O + PPh3
RuCl3ÁnH2O + 2PPh3
RuCl3ÁnH2O + 3PPh3
Ru3(CO)12+2PPh3
6
7c
8d
Ru(h -cod)(h -cot) + 2PPh3
4
6
9e
10
Ru(h -cot)(h -dmfm)2 + 2PPh3
Ru(CO)3(PPh3)2
6
2
11
12RhCl(PPh
Pd(PPh3)4
)
720
100
55
3
3
a1a (4.0 mmol), catalyst (0.20 mmol as a metal atom), allyl acetate (30 mmol), K2CO3 (10 mmol), toluene (8.0 mL) under CO (10 atm) at 160 ꢀC for
2 0 h.bDetermined by GLC based on the amount of 1a charged. cRu3(CO)12 (0.067 mmol) and PPh3 (0.40 mmol). dcod = 1,5-cyclooctadiene, cot =
1,3,5-cyclooctatriene. edmfm = dimethyl fumarate.
Assistance Foundation, and the Yamada Science Foundation.
References and Notes
1
a) E. L. Muetterties, ‘‘Transition Metal Hydrides,’’ Marcel Decker, New
York (1971). b) H. E. Bryndza and W. Tam, Chem. Rev., 88, 1163 (1988). c)
J. R. Fulton, A. W. Holland, D. J. Fox, and R. G. Bergman, Acc. Chem. Res.,
35, 44 (2002).
2a) J. C. M. Ritter and R. G. Bergman,
J. Am. Chem. Soc., 120, 6826 (1998),
and references therein. b) I. Saura-Llamas and J. A. Gladysz, J. Am. Chem.
Soc., 114, 2136 (1992).
3
4
5
6
Y.-Z. Chen, W. C. Chan, C. P. Lau, H. S. Chu, H. L. Lee, and G. Jia,
Organometallics, 16, 1241 (1997), and references therein.
T. Kondo, K. Kodoi, T. Mitsudo, and Y. Watanabe, J. Chem. Soc., Chem.
Commun., 1994, 755.
T. Kondo, K. Kodoi, E. Nishinaga, T. Okada, Y. Morisaki, Y. Watanabe, and
T. Mitsudo, J. Am. Chem. Soc., 120, 5587 (1998).
a) T. Hosokawa, K. Maeda, K. Koga, and I. Moritani, Tetrahedron Lett., 14,
739 (1973). b) T. Hosokawa, H. Ohkata, and I. Moritani, Bull. Chem. Soc.
Jpn., 48, 1533 (1975). c) T. Hosokawa, T. Uno, and S. Murahashi, J. Chem.
Soc., Chem. Commun., 1979, 475. d) A. I. Roshchin, S. M. Kel’chevski, and
N. A. Bumagin, J. Organomet. Chem., 560, 163 (1998). e) R. C. Larock, L.
Wei, and T. R. Hightower, Synlett, 1998, 522.
7
Ruthenium-catalyzed transformation of 2-allylphenols, see: a) K. Hori, H.
Kitagawa, A. Miyoshi, T. Ohta, and I. Furukawa, Chem. Lett., 1998, 1083. b)
T. Sato, N. Komine, M. Hirano, and S. Komiya, Chem. Lett., 1999, 441.
T. Hosokawa, M. Hirata, S. Murahashi, and A. Sonoda, Tetrahedron Lett.,
17, 1821 (1976).
Scheme 1.
8
9
give an (alkoxy)(ꢂ-allyl)ruthenium intermediate. Further intra-
molecular insertion of an alkene moiety into an O-[Ru] bond,
followed by ꢀ-hydride elimination/isomerization gave 2,3-
dihydrofuran, together with the formation of propene.13 K2CO3
acts as a base to neutralize the generated acetic acid.
In conclusion, we have found novel ruthenium-catalyzed
oxidative cyclization of 1,1-disubstituted 4-penten-1-ols to 2,3-
dihydrofurans. All 2,3-dihydrofurans prepared in this study are
new compounds, which are quite attractive as novel functional
monomers. Mechanistic study and application of the present
reaction to organic synthesis are now under progress.
a) T. Kondo, T. Mukai, and Y. Watanabe, J. Org. Chem., 56, 487 (1991). b) T.
Kondo, T. Okada, and T. Mitsudo, J. Am. Chem. Soc., 124, 186 (2002).
10 Under the present reaction conditions, both RuCl2(PPh3)3 catalyst and
RuCl3Á3H2O catalyst with PPh3 could be reduced to a common active Ru(0)
species, which can explain the effectiveness of these Ru(II) and Ru(III)
catalysts as Ru(0) catalysts for the present oxidative cyclization reaction.
11 The reaction using 1,1-disubstituted 4-hexen-1-ols which have methyl
substituents on the terminal olefinic carbon, such as 2-phenyl-5-hepten-2-ol,
is quite complicated. The yield of normal oxidative cyclization product, 2,5-
dimethyl-5-phenyl-4,5-dihydrofuran, was quite low (>5%), while the
oxidative cyclocarbonylation on the phenyl substituent occurred to give
unexpected 3-methyl-3-(pent-3-enyl)phthalide in 48% yield. Similar oxida-
tive cyclocarbonylation proceeded quantitatively with 1,1-disubstituted 5-
hexen-1-ols. Further studies are apparently required for these reactions.
12Chemistry of ꢂ-allylruthenium complexes, see: a) T. Kondo, H. Ono, N.
Satake, T. Mitsudo, and Y. Watanabe, Organometallics, 14, 1945 (1995). b)
Y. Morisaki, T. Kondo, and T. Mitsudo, Organometallics, 18, 4742(1999).
c) T. Kondo and T. Mitsudo, Curr. Org. Chem., 6, 1163 (2002).
This work was supported in part by a Grants-in-Aid for
Scientific Research (B), and Scientific Research on Priority Areas
(A) ‘‘Exploitation of Multi-Element Cyclic Molecules’’ from the
Japan Society for the Promotion of Science and the Ministry of
Education, Culture, Sports, Science and Technology, Japan. T.K.
acknowledges financial support from the UBE Foundation,
General Sekiyu Research & Development; Encouragement &
13 After run 10 in Table 1, a reasonable amount of propene was evolved in the
gas phase (4.4 mmol), and we believe that allyl acetate operates as an
effective hydrogen acceptor by hydrogenolysis of allyl acetate to propene
4;9
and acetic acid as in our previous works. No propyl acetate, a simple
hydrogenated product of allyl acetate, was detected by careful GC analysis.