Communications
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[8] The discussion herein is limited to enyne RCM
proceeding intermolecularly via alkylidene
intermediates.
[9] Detailedkinetic investigations on Ru-cata-
lyzedalkene/alkyne co-metathesis have dem-
onstratedthat the rate-limiting interaction can
involve either the alkene or the alkyne,
depending on the substitution patterns: B. R.
Galan, A. J. Giessert, J. B. Keister, S. T. Diver,
J. Am. Chem. Soc. 2005, 127, 5762 – 5763.
Figure 1. Relationships between 13C incorporation (%) at the vinyl terminus( y axis) in substrates and
productsasa function of conversion ( x axis) for the co-reaction of 5, [D7]-6, 7, and [D5]-8 asshown in
Scheme 6.
[10] a) M. Mori, N. Sakakibara, A. Kinoshita, J. Org. Chem. 1998, 63,
6082 – 6083; b) T. Kitamura, Y. Sato, M. Mori, Adv. Synth. Catal.
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[11] G. C. Lloyd-Jones, R. G. Margue, unpublished results.
[12] For additional examples of successful application of “Moriꢀs
conditions” see: a) J. S. Clark, R. J. Townsend, A. J. Blake, S. J.
Teat, A. Johns, Tetrahedron Lett. 2001, 42, 3235 – 3238; b) Q.
Yao, Org. Lett. 2001, 3, 2069 – 2072; c) C. S. Poulsen, R. Madsen,
J. Org. Chem. 2002, 67, 4441 – 4449; d) H. Guo, R. J. Madhushaw,
F.-M. Shen, R.-S. Liu, Tetrahedron 2002, 58, 5627 – 5637; e) M. E.
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9582 – 9583; g) F. Dolhem, C. Liꢁvre, G. Demailly, Eur. J. Org.
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Chang, Org. Lett. 2003, 5, 3041 – 3043; for examples of RCM of
enynes where “Moriꢀs conditions” are not effective, see: i) M. A.
Leeuwenburgh, C. M. M. Appeldoorn, P. A. V. van Hooft, H. S.
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Mori, Org. Lett. 2002, 4, 803 – 805.
Figure 2. The 13C/12C ratio at the vinyl terminus( y axis) in 6 and 8 asa
function of conversion (c, %, x axis) of 5 and 7. The linear regressions
are: 13C/12C=0.19ꢁ0.03c + 3.86ꢁ0.82 and 13C/12C=0.05ꢁ0.002c +
1.65ꢁ0.05, respectively.
[13] The rate of RCM of dimethyl diallyl malonate (cf. dimethyl allyl
propargyl malonate 5) catalyzedby 3 in CH2Cl2 was foundto be
identical under N2 (1 atm) andethylene (1 atm), throughout the
entire course of the reaction.
spread, and thus mechanism B may apply to a broader range
of substrates than previously considered.
[14] Strong supporting evidence for the “ene-then-yne” sequence
(cycle B), including NMR spectroscopic observation and iso-
lation of Ru–alkylidenes that are plausible intermediates, has
been reported, see: a) T. R. Hoye, S. M. Donaldson, T. J. Vos,
Org. Lett. 1999, 1, 277 – 279; b) M. P. Schramm, D. S. Reddy,
S. A. Kozmin, Angew. Chem. 2001, 113, 4404 – 4407; Angew.
Chem. Int. Ed. 2001, 40, 4274 – 4277; c) E. C. Hansen, D. Lee, J.
Am. Chem. Soc. 2003, 125, 9582 – 9583; however, to the best of
our knowledge, a conclusive method for distinguishing turnover
by mechanism A versus B has yet to be presented; d) The ene-
yne-ene mechanism was suggestedfor the tandem RCM of a
dieneyne: S. H. Kim, N. Bowden and R. H. Grubbs, J. Am.
Chem. Soc. 1994, 116, 10801 – 10802.
Received: June 25, 2005
Publishedonline: October 20, 2005
Keywords: carbenes · isotopic labeling · metathesis ·
.
reaction mechanisms · ruthenium
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ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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