the smallest cycloalkenes, cyclopropenes7 are highly strained
but readily accessible substances,8 which have been serving
as useful building blocks in many organic reactions.9 For
example, 3,3-diphenylcyclopropene has been well-known as
an important starting material for the synthesis of valuable
ruthenium-involved vinylalkylidene olefin metathesis catalyst
via a ring-opening process.2 Since cyclopropenes cannot be
formed by ring-closing metathesis (RCM) due to the highly
strained energy,10 the ring-opening of the ruthenacyclobutane
intermediate is irreversible. In such cases, cyclopropenes are
more inclined to undergo ring-opening metathesis polym-
erization (ROMP)11 rather than ring-opening metathesis/
cross-metathesis (ROM/CM). However, several ROM/CM
processes involving cyclopropenes have recently been dis-
closed. For instance, ROM/CM of cyclopropenone ketals has
been successfully applied to the synthesis of Bistramide A
and Routiennocin.12 More recently, Hoveyda and co-workers
reported enantioselective13 and diastereoselective14 ROM/
CM of 3,3-disubstituted cyclopropenes, giving functionalized
homoallylic carboxylic esters and homoallylic alcohols in
moderate to good yields along with good stereoselectivities.
Furthermore, Meyer and co-workers also reported intramo-
lecular metathesis reactions of cyclopropenes via a ROM/
RCM (ring-rearrangement metathesis) sequence, affording
a variety of heterocyclic compounds in moderate to excellent
yields.15 Inspired by these pioneering reports and our
previous unsuccessful attempts on using tetra-substituted
arylvinylcyclopropenes16 as substrates in olefin metathesis,
we synthesized a series of electron-deficient, sulfonamide-
linked 1,6-cyclopropene-ynes 1 via a nucleophilic substitution
followed by a rhodium-catalyzed cyclopropenation sequence
(Scheme 1; for details, please see the Supporting Information)
to examine the enyne metathesis. In this communication, we
wish to report a novel and remarkable ROM/RCM/cross-
metathesis of 1,6-cyclopropene-ynes and olefins. To the best
Scheme 1. Two-Step Synthesis of 1,6-Cyclopropene-ynes 1
of our knowledge, this finding constitutes the first report on
the ring-closing enyne metathesis (RCEYM) of cyclopro-
penes.
Figure 1 shows the catalysts that are available for ROM/
RCM/cross-metathesis of 1,6-cyclopropene-ynes 1 and ole-
Figure 1. Catalysts used in ROM/RCM/cross-metathesis of 1,6-
cyclopropene-yne 1a in Table SI-2.
fins 2. Ru gen-1 and Ru gen-2 are the first- and second-
generation Grubbs’ ruthenium complexes that are widely
used in olefin metathesis.3,5 Ru-3 is a modified Hoveyda-
Grubbs catalyst developed by Zhan.17 Catalyst kits Ru-4 and
Ru-5 developed by Dixneuf’s group have also been widely
used in enyne metathesis.18
Initial examination of the reaction was performed by using
ethyl 2-((4-methyl-N-(prop-2-ynyl)phenylsulfonamido)meth-
yl)cycloprop-2-enecarboxylate (1a, 0.1 mmol) as the sub-
strate in the presence of Ru gen-1 (10 mol %). We found
that using styrene 2a as the solvent and 10 mol % of catalyst
loading (Ru gen-1), 3a can be obtained in maximum overall
yields (Please see Table SI-2 in the Supporting Information
for the details).
(7) Baird, M. S. Cyclopropenes: Synthesis: By Construction of the
System. Houben-Weyl; Thieme: Stuttgart, Germany, 1997; Vol. E17d/2, p
2695.
(8) (a) Rubin, M.; Rubina, M.; Gevorgyan, V. Chem. ReV. 2007, 107,
3117. (b) Rubin, M.; Rubina, M.; Gevorgyan, V. Synthesis 2006, 1221. (c)
Fox, J. M.; Yan, N. Curr. Org. Chem. 2005, 9, 719. (d) Walsh, R. Chem.
Soc. ReV. 2005, 34, 714. (e) Dolbier, W. R., Jr.; Battiste, M. A. Chem.
ReV. 2003, 103, 1071. (f) Sekiguchi, A.; Lee, V. Y. Chem. ReV. 2003, 103,
1429. (g) Chen, K.-C.; Lee, G.-A. Huaxue 2006, 64, 73. (h) Baird, M. S.
Chem. ReV. 2003, 103, 1271.
(9) (a) Binger, P.; Bu¨ch, H. M. Top. Curr. Chem. 1987, 135, 77. (b)
Jennings, P. W.; Johnoson, L. L. Chem. ReV. 1994, 94, 2241. (c) Baird,
M. S. In Cyclopropenes: Transformations; de Meijere, A., Ed.; Houben-
Weyl: Stuttgart, Germany, 1996; Vol. E17d/2, p 2781. (d) Nakamura, M.;
Isobe, H.; Nakamura, E. Chem. ReV. 2003, 103, 1295.
(10) Collins, S. K. J. Organomet. Chem. 2006, 691, 5122.
(11) (a) Binder, W. H.; Kurzhals, S.; Pulamagatta, B.; Decker, U.; Pawar,
G. M.; Wang, D.; Ku¨hnel, C.; Buchmeiser, M. R. Macromolecules 2008,
41, 8405. (b) Singh, R.; Schrock, R. R. Macromolecules 2008, 41, 2990.
(c) Biewalski, C. W.; Grubbs, R. H. Prog. Polym. Sci. 2007, 32, 1. (d)
Singh, R.; Czekelius, C.; Schrock, R. R. Macromolecules 2006, 39, 1316.
(e) Buchmeiser, M. R. Chem. ReV. 2000, 100, 1565.
(16) Transformations of tetra-substituted arylvinylcyclopropenes: (a)
Shao, L.-X.; Zhang, Y.-P.; Qi, M.-H.; Shi, M. Org. Lett. 2007, 9, 117. (b)
Zhu, Z.-B.; Shi, M. Chem.sEur. J. 2008, 14, 10219. (c) Zhu, Z.-B.; Shi,
M. Chem.sEur. J. 2009, 15, 7543. (d) Zhu, Z.-B.; Shi, M. J. Org. Chem.
2009, 74, 2481. (e) Yu, F.-F.; Yang, W.-G.; Shi, M. Chem. Commun. 2009,
1392. (f) Zhu, Z.-B.; Shi, M. Org. Lett. 2009, 11, 5278.
(12) (a) Michaut, M.; Parrain, J.-L.; Santelli, M. Chem. Commun. 1998,
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(17) For original documents of Hoveyda-Grubbs catalyst, see: (a)
Kingsbury, J. S.; Harrity, J. P. A.; Bonitatebus, P. J.; Hoveyda, A. H. J. Am.
Chem. Soc. 1999, 121, 791. (b) Garber, S. B.; Kingsbury, J. S.; Gray, B. L.;
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see: (c) Zhan, Z.-Y. WO Patent 2007003135, 2007.
(13) Giudici, R. E.; Hoveyda, A. H. J. Am. Chem. Soc. 2007, 129, 3824.
(14) Hoveyda, A. H.; Lombardi, P. J.; O’Brien, R. V.; Zhugralin, A. R.
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