Allenylidene-to-indenylidene rearrangement in arene-ruthenium complexes: A key step to highly active catalysts for olefin metathesis reactions

Article abstract of DOI:10.1021/ja0579762

The allenylidene-ruthenium complexes [(η⁶-arene)RuCl(=C=C= CR₂)(PR′₃)]OTf (R₂ = Ph; fluorene, Ph, Me; PR′₃ = PCy₃, P^IPr₃, PPh₃) (OTf = CF₃SO

Full text of DOI:10.1021/ja0579762

Published on Web 03/04/2006
Allenylidene-to-Indenylidene Rearrangement in
Arene-Ruthenium Complexes: A Key Step to Highly Active
Catalysts for Olefin Metathesis Reactions
Ricardo Castarlenas,* Chloe´ Vovard, Ce´dric Fischmeister, and Pierre H. Dixneuf*
Contribution from the Institut de Chimie de Rennes, UMR 6509 CNRSsUniVersite´ de Rennes,
Organome´talliques et Catalyse, Campus de Beaulieu, 35042 Rennes, France
Received November 23, 2005; E-mail: pierre.dixneuf@univ-rennes1.fr
Abstract: The allenylidene-ruthenium complexes [(η6-arene)RuCl(dCdCdCR2)(PR′3)]OTf (R2 ) Ph;
fluorene, Ph, Me; PR′3 ) PCy3, PiPr3, PPh3) (OTf ) CF3SO3) on protonation with HOTf at -40 °C are
completely transformed into alkenylcarbyne complexes [(η6-p-cymene)RuCl(tCCHdCR2)(PR3)](OTf)2. At
-20 °C the latter undergo intramolecular rearrangement of the allenylidene ligand, with release of HOTf,
into the indenylidene group in derivatives [(η6-arene)RuCl(indenylidene)(PR3)]OTf. The in situ-prepared
indenylidene-ruthenium complexes are efficient catalyst precursors for ring-opening metathesis poly-
merization of cyclooctene and cyclopentene, reaching turnover frequencies of nearly 300 s-1 at room
temperature. Isolation of these derivatives improves catalytic activity for the ring-closing metathesis of a
variety of dienes and enynes. A mechanism based on the initial release of arene ligand and the in situ
generation of the active catalytic species RuCl(OTf)(dCH2)(PR3) is proposed.
Chart 1
Introduction
The discovery of well-defined metal-alkylidene complexes
as powerful catalysts for the cleavage and formation of CdC
bonds has enabled olefin metathesis to reach impressive
developments that have largely improved synthetic methods and
contributed to materials science.1 This many-faceted revolution
brought about by alkene metathesis catalysis has just been
recognized by the award of the 2005 Nobel Prize in Chemistry
to Yves Chauvin for the discovery of mechanisms based on an
alkylidene-metal intermediate2 and to Richard R. Schrock and
Robert H. Grubbs for their discovery and fruitful applications
of efficient, well-defined molybdenum-alkylidene1d-f and
ruthenium-alkylidene1g-i alkene metathesis catalysts.
Stable alkylidene-ruthenium-based precatalysts have broad-
ened the scope of the reaction due to their high tolerance toward
a variety of functional groups while maintaining an excellent
catalytic activity. The commercially available complexes RuCl2-
(dCHPh)(PCy3)2 (1)3 and RuCl2(dCHPh)(PCy3)(NHC) (NHC
) N-heterocyclic carbene) (2)4 (Chart 1), in which one hindered
phosphine PCy3 has been replaced by a more electron-donating
NHC ligand, have played a key role, showing excellent activity
in a large number of applications including ring-opening
metathesis polymerization (ROMP),5 ring-closing metathesis
(RCM),6 acyclic diene metathesis polymerization (ADMET),7
and cross metathesis (CM).8 It was established that the release
of one phosphine in complexes 1 and 2 to generate a 14-electron
intermediate is the determining step of the catalytic reaction.9
(1) Recent reviews: (a) Nicolaou, K. C.; Bulger, P. G.; Sarlah, D. Angew.
Chem., Int. Ed. 2005, 44, 4490. (b) Grubbs, R. H. Tetrahedron 2004, 60,
7117. (c) Castarlenas, R.; Fischmeister, C.; Bruneau, C.; Dixneuf, P. H. J.
Mol. Catal. A: Chem. 2004, 213, 31. (d) Schrock, R. R. J. Mol. Catal. A:
Chem. 2004, 213, 21. (e) Schrock, R. R.; Hoveyda, A. H. Angew. Chem.,
Int. Ed. 2003, 42, 4592. (f) Schrock, R. R.; Murdzek, J. S.; Bazan, G. C.;
Robbins, J.; Di Mare, M.; O’Regan, M. J. Am. Chem. Soc. 1990, 112, 3875.
(g) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18. (h) Fu, G.
C.; Nguyen, S. T.; Grubbs, R. H. J. Am. Chem. Soc. 1993, 115, 9856. (i)
Nguyen, S. T.; Johnson, L. K.; Grubbs, R. H.; Ziller, J. W. J. Am. Chem.
Soc. 1992, 114, 3974. (j) Fu¨rstner, A. Angew. Chem., Int. Ed. 2000, 39,
3012. (k) Connon, S. J.; Blechert, S. Angew. Chem., Int. Ed. 2003, 42,
1900.
(4) Ruthenium complex with unsaturated NHC: (a) Huang, J.; Nolan, S. P.;
Petersen, J. L. J. Am. Chem. Soc. 1999, 121, 2674. (b) Scholl, M.; Trnka,
T. M.; Morgan, J. P.; Grubbs, R. H. Tetrahedron Lett. 1999, 40, 2247. (c)
Weskamp, T.; Kohl, F. J.; Hieringer, W.; Gleich, D.; Herrmann, W. A.
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Herrmann, W. A. J. Organomet. Chem. 1999, 582, 362. (e) Ruthenium
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Polymerization; Buchmeiser, M. K., Ed.; Advances in Polymer Science
176; Springer-Verlag GmbH: Berlin, 2005; Chapter 2, pp 43-87. (b)
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9
10.1021/ja0579762 CCC: $33.50 © 2006 American Chemical Society
J. AM. CHEM. SOC. 2006, 128, 4079-4089
4079

A R T I C L E S
Castarlenas et al.
Thus, the introduction of chelating isopropoxybenzylidene
ligand10a has led to a new type of very active phosphine-free
ruthenium-alkylidene catalysts (3) that can be easily recovered
after achievement of catalytic reaction.10 More recently, various
ruthenium-based metathesis catalysts have been prepared by
replacement of one or two chloride ligands.11
Despite the profit brought by these neutral ruthenium-
alkylidene derivatives, efforts still need to be made to prepare
readily accessible, active, and robust catalyst precursors in order
to improve the scope of applications and innovate in catalyst
or initiator designing. In this context, ruthenium-vinylidene12
or ruthenium-allenylidene13-16 derivatives, readily obtained
from easy-to-prepare or commercially available ruthenium
complexes and simple terminal alkynes or propargyl alcohols,
have been revealed as a valid alternative.
The ionic 18-electron ruthenium-allenylidene complexes of
formula [(η6-p-cymene)RuCl(dCdCdCAr2)(PR3)]X (4), gener-
ated from [RuCl(PR3)(p-cymene)]X and HCtCC(OH)Ar2,
promoted RCM of dienes and enynes13,15,16 as well as ROMP16
and provided an unprecedented example of the involvement of
allenylidenes in alkene metathesis. The catalytic mechanism
involves the initial decoordination of the η6-bound p-cymene
ligand.13,17,18 Kinetic and spectroscopic studies have revealed
that on thermal activation the ionic 18-electron allenylidene
complex 4 actually was progressively transformed into a
noncharacterized alkene metathesis catalytic species.19
(6) (a) Wallace, D. J. Angew. Chem., Int. Ed. 2005, 44, 1912. (b) Hercouet,
A.; Baudet, C.; Carboni, B. Tetrahedron Lett. 2004, 45, 8749. (c) Fustero,
S.; Bartolome´, A.; Sanz-Cervera, J. F.; Sa´nchez-Rosello´, M.; Garc´ıa-Soler,
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Lee, C. W.; Choi, T.-L.; Grubbs, R. H. J. Am. Chem Soc. 2002, 124, 3224.
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M.; Dixneuf, P. H. Eur. J. Org. Chem. 2001, 20, 3891. (f) Maier, M. E.
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Buchmeiser, M. K., Ed.; Advances in Polymer Science 176; Springer-Verlag
GmbH: Berlin, 2005; Chapter 1, pp 1-42. (b) Qin, H.; Chakulski, B. J.;
Rousseau, I. A.; Chen, J.; Xie, X. Q.; Mather, P. T.; Constable, G. S.;
Coughlin, E. B. Macromolecules 2004, 37, 5239. (c) Courchay, F. C.;
Sworen, J. C.; Wagener, K. B. Macromolecules 2003, 36, 8231.
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Y.; Marciniec, B.; Kubicki, M. Chem. Eur. J. 2004, 10, 1239. (c) Nakamura,
S.; Hirata, Y.; Kurosaki, T.; Anada, M.; Kataoka, O.; Kitagaki; S.;
Hashimoto, S. Angew. Chem., Int. Ed. 2003, 42, 5351. (d) Chatterjee, A.
K.; Choi, T.-L.; Sanders, D. P.; Grubbs, R. H. J. Am. Chem. Soc. 2003,
125, 11360. (e) Tanaka, K.; Nakanishi, K.; Berova, N. J. Am. Chem. Soc.
2003, 125, 10802. (f) Van Schalkwyk, C.; Vosloo, H. C. M.; du Plessis, J.
A. K. AdV. Synth. Catal. 2002, 344, 781.
Other ruthenium-allenylidenes, such as RuCl2(PCy3)2(dCd
CdCPh2)14f and [RuCl(NHC)(arene)dCdCdCAr2]X,14g have
led to moderate alkene metathesis catalytic activity. By contrast,
an attempt to make RuCl2(PPh3)2dCdCdCPh2 failed, but the
formation of an inert RuCl2(PPh3)2(ind) (ind ) 3-phenylinde-
nylidene) complex was observed instead.20 The displacement
of PPh3 by PCy3 actually afforded the active catalyst precursor
RuCl2(PCy3)2(ind) (5) that has displayed excellent performance
for a wide range of organic substrates21 and is now commercially
available.
Here we report the selective transformation of allenylidene
complexes 4 into alkene metathesis catalytic species. In the
presence of acid, these (arene)ruthenium-allenylidene com-
plexes in situ rearrange, via alkenylcarbyne intermediates [(η6-
p-cymene)RuCl(tCCHdCR2)(PR3)]X2, into (arene)ruthenium
indenylidene derivatives [(η6-arene)RuCl(ind)(PR3)]X (eq 1).
(9) (a) Sanford, M. S.; Ulman, M.; Grubbs, R. H. J. Am. Chem. Soc. 2001,
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126, 9592. (e) Fomine, S.; Martinez Vargas, S.; Tlenkopatchev, M. A.
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2003, 22, 3634. (e) Krause, J. O.; Lubbad, S.; Nuyken, O.; Buchmeiser,
M. R. AdV. Synth. Catal. 2003, 345, 996.
This new acid-promoted process allows the first direct observa-
tion of an allenylidene-to-indenylidene rearrangement that brings
a new light in allenylidene- and indenylidene-metal complex
(17) Release of the arene ligand has been described in ruthenium alkylidene-
free complexes of type (η6-p-cymene)RuX2L (L ) PR3, NHC) that could
be photochemically17 or thermally18 activated. (a) Delaude, L.; Demonceau,
A.; Noels, A. F. Chem. Commun. 2001, 986. (b) Hafner, A.; Mu¨hlebach,
A.; van der Schaaf, P. A. Angew. Chem., Int. Ed. Engl. 1997, 36, 2121.
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24, 4343. (b) Castarlenas, R.; Eckert M.; Dixneuf, P. H. Angew. Chem.,
Int. Ed. 2005, 44, 2576. (c) Castarlenas, R.; Alaoui-Abdallaoui, I.; Se´meril,
D.; Mernari, B.; Guesmi, S.; Dixneuf, P. H. New J. Chem. 2003, 27, 6. (d)
Delaude, L.; Szypa, M.; Demonceau, A.; Noels, A. F. AdV. Synth. Catal.
2002, 344, 749. (e) Se´meril, D.; Cle´ran, M.; Bruneau, C.; Dixneuf, P. H.
AdV. Synth. Catal. 2001, 343, 184. (f) Demonceau, A.; Stumpf, A. W.;
Saive, E.; Noels, A. F. Macromolecules 1997, 30, 3127.
(19) Bassetti, M.; Centola, F.; Se´meril, D.; Bruneau, C.; Dixneuf, P. H.
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4080 J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006

Allenylidene-to-Indenylidene Rearrangement
A R T I C L E S
Table 1. Acid-Promoted Cyclooctene Polymerization at Room
Temperaturea
3
yield 10-
(%)
×
%
TOF
1
entry catalyst
ratiob
acidc
time
Mn
PDI cis (min-
)
1
2
3
4
5
6
7
8
9
9
4a
4a
4a
4a
1 000
15 h
95 143 1.9 27
92 224 1.7 40
95 238 1.6 38
97 387 1.5 28 1 940
88 857 1.4 35 17 600
1
920
950
1 000 HBF4 (5 equiv)
1 000 HOTf (5 equiv)
10 000 HOTf (5 equiv)
1 min
1 min
5 min
4a 100 000 HOTf (100 equiv) 5 min
4b
4c
4d
4e
4f
10 000 HOTf (5 equiv)
10 000 HOTf (5 equiv)
10 000 HOTf (5 equiv)
10 000 HOTf (5 equiv)
1 000 HOTf (5 equiv)
10 min 73 220 1.8 25
8 h 25 107 1.9 22
20 min 90 263 1.9 32
5 min
16 h
730
5
450
92 286 1.6 26 1 840
<5
1
Figure 1. Cyclopentene polymerization monitorized by H NMR experi-
ments at 0 °C.
a 4.5 × 10-3 mol of cyclooctene in 2.5 mL of PhCl. b [cyclooctene]/
[Ru]. c Related to complex.
the less electron-donating phosphine PPh3 (4c) or the introduc-
tion of electron-releasing groups in the phenyl rings (4b) reduces
catalytic activity. The catalytic system generated starting from
complex 4d, which bears a stronger electron-donor ligand
instead of PCy3, presents surprisingly poorer activity. The more
strongly coordinated η6-hexamethylbenzene ligand in 4f makes
it almost inactive.
Chart 2
Due to the high activity presented by these in situ-generated
catalysts for ROMP of cyclooctene, polymerization of the less
reactive cyclopentene was evaluated. To prevent catalyst
decomposition, catalytic assays were carried out at 0 °C. A
Schlenk tube was charged with allenylidene complex (4a, 4b,
or 4e), 1000 equiv of cyclopentene (2.33 M), PhCl, and 5 equiv
of triflic acid. To compare the catalytic activity, experiments
with the well-known stable ruthenium-alkylidene catalysts 1
and 2 were carried out at room temperature. The results are
compiled in Figure 1. It is observed that the catalytic activity
of the in situ-generated systems from 4a, 4b, and 4e surpasses
that of the commercial complexes 1 and 2. In addition, when 5
equiv of triflic acid was added to solution containing catalyst
2, even lower yields and TOF were obtained, in agreement with
the previous observation that addition of HCl does not improve
the activity of pure 2.23
2. Elucidation of the Allenylidene- to Indenylidene-
Ruthenium Rearrangement. To understand the nature of the
catalytic species generated on addition of acid to ruthenium-
allenylidene complexes and control their synthesis, low-tem-
perature NMR studies were performed. It was observed that
addition of triflic acid to 4a provokes the rearrangement of the
allenylidene moiety into indenylidene species [(η6-p-cymene)-
RuCl(ind)(PCy3)]OTf (7) via a dicationic alkenylcarbyne in-
termediate, [(η6-p-cymene)RuCl(tCCHdCPh2)(PCy3)](OTf)2
(6) (Scheme 1). Figure 2 displays the transformation 4a f 6
f 7 based on 31P{1H} NMR spectra. It is shown that the
allenylidene complex 4a is readily transformed into a new
species 6, which disappears to give 7 in 25 min at -15 °C.
The first step is the protonation of the nucleophilic Câ of the
allenylidene ligand of 4a that takes place at -40 °C. Other
ruthenium-alkenylcarbyne complexes have been synthesized
by a similar procedure.14d,24 The 13C{1H} NMR spectrum of 6
displays a low-field doublet at 328.1 ppm (2JP-C ) 11 Hz) for
the RutC carbon atom. The olefinic proton (δΗ ) 7.05)
chemistry and catalysis and shows that indenylidene-ruthenium-
(arene) complexes are very active catalysts in a variety of alkene
metathesis applications. The first elements of this detailed study
were previously reported.22
Results and Discussion
1. Evidence for Enhancement of Catalytic Activity for
ROMP Reactions of Allenylidene-Ruthenium Complexes
on Protonation. Preliminary results on cyclooctene polymer-
ization promoted by allenylidene-ruthenium(II) complexes
show that the treatment of the initiator [(η6-p-cymene)RuCl(d
CdCdCPh2)(PCy3)]OTf (OTf ) CF3SO3) (4a) with a strong
acid largely increases polymerization rates. Addition of 5 equiv
of HBF4 or HOTf to catalytic solutions of 4a in chlorobenzene
caused the polymerization of 1000 equiv of cyclooctene in 1
min, increasing turnover frequency (TOF) values by 3 orders
of magnitude (Table 1, entries 1-3). The in situ-prepared
catalytic system is also active with higher monomer loading;
thus, it polymerized 10 000 equiv of cyclooctene in 5 min,
showing a conversion of 97% corresponding to a TOF of 1940
min-1 (entry 4). A tremendous increase of the TOF value to
17 000 min-1 was reached when 100 000 equiv of monomer
was loaded (entry 5). It was verified that polymerization does
not take place with triflic acid in the absence of ruthenium-
allenylidene precatalyst.
Slight modifications of the starting allenylidene complex were
made by changing substituents on the phenyl groups, [(η6-p-
cymene)RuCl{dCdCdC(p-OMe-Ph)2}(PCy3)]OTf (4b), the
phosphine, [(η6-p-cymene)RuCl(dCdCdCPh2)(PPh3)]OTf (4c)
and [(η6-p-cymene)RuCl(dCdCdCPh2)(IMes)]OTf (IMes )
1,3-bis(2,4,6-trimethylphenyl)imidazolylidene) (4d), or the η6-
arene ligand, [(η6-1,2,4,5-tetramethylbenzene)RuCl(dCdCd
CPh2)(PCy3)]OTf (4e) and [(η6-hexamethylbenzene)RuCl(dCd
CdCPh2)(PCy3)]OTf (4f) (Chart 2). Addition of 5 equiv of triflic
acid to solutions of 4b-e promoted the formation of cycloocte-
namer as well (entries 6-9). Only precursor 4e led to results
similar to those observed for 4a, showing that either the use of
(23) Morgan, J. P.; Grubbs, R. H. Org. Lett. 2000, 2, 3153.
(24) (a) Cadierno, V.; Die´z, J.; Garc´ıa-Garrido, S. E.; Gimeno, J. Organometallics
2005, 24, 3111. (b) Rigaut, S.; Touchard, D.; Dixneuf, P. H. Organome-
tallics 2003, 22, 3980. (c) Bustelo, E.; Jimenez-Tenorio, M.; Meriter, K.;
Puerta, M. C.; Valerga, P. Organometallics 2002, 21, 1903.
(22) Castarlenas, R.; Dixneuf, P. H. Angew. Chem., Int. Ed. 2003, 42, 4524.
9
J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006 4081

A R T I C L E S
Castarlenas et al.
Chart 3
Scheme 2
Figure 2. Addition of 2 equiv of triflic acid to 4a at -15 °C: evolution of
31P{1H} NMR spectra as a function of time.
Scheme 1
rearrangement was previously observed from the trans-[Cl-
(dppm)2RudCdCdCdCdCPh2]PF6 intermediate via ortho-
phenyl electrophilic substitution, but with the electrophilic Cγ
carbon atom.26 Since our initial communication,22 related
osmium-indenylidene derivatives, characterized by X-ray
crystallographic analysis, have been prepared by protonation
of allenylidene-osmium complexes.27
Previously, it has been shown that both indenylidene21 and
carbyne28 complexes were able to act as olefin metathesis
initiators. To establish which of the derivatives 6 or 7 is the
actual precatalyst, RCM of diallyltosylamide (8) into 1-tosyl-
2,5-dihydropyrrole (9), mediated by the catalytic system made
from 4a (2 mol %) and 5 equiv of HOTf, was monitored by
NMR experiments. Formation of alkenylcarbyne complex 6 was
observed by 31P{1H} NMR, but the RCM product 9 was not
detected after 1 h at -40 °C. By contrast, warming the solution
to 0 °C caused the formation of indenylidene derivative 7, with
the appearance of the RCM product 9, reaching 99% of
conversion in 30 min (Scheme 1).
correlates with Câ (130.5 ppm) in a 1H-13C HMQC experiment.
1
More interestingly, the H-13C HMBC spectrum displays an
interaction between the alkenylcarbyne hydrogen atom and Cγ
(193.2 ppm), but no cross-peak is observed with CR located at
the same bond separation. Similar behavior has been observed
for the alkenylcarbyne complex RuCl3(PPh3)2{tCCHdC(Me)2}.25
Warming the solution to -20 °C leads to the formation of
indenylidene derivative 7, resulting from the ortho-phenyl
substitution by the electrophilic CR carbon of 6, with release of
the added triflic acid. Thus, in the dicationic species 6 a stronger
contribution of the canonical form 6B can favor this rearrange-
ment (eq 2).
[Ru+tCsCHdCPh
(6A)
RudC+sCHdCPh ]
2 T
(2)
2
(6B)
The 13C{1H} NMR spectrum of 7 shows a lower-field doublet
(2JP-C ) 10 Hz) at 334.1 ppm corresponding to the RudC
To corroborate the lack of activity of alkenylcarbyne deriva-
tives, complex [(η6-p-cymene)RuCl(tCCHdCR2)(PCy3)](OTf)2
(11) (R2 ) 2,2′-biphenyldiyl), bearing a fluorene group on Cγ
of the alkenylcarbyne moiety, was prepared by acid treatment
of allenylidene [(η6-p-cymene)RuCl(dCdCdCR2)(PCy3)]OTf
(10) at -40 °C (Scheme 2). Formation of a new complex 11 is
1
carbon atom. The H spectrum displays a singlet at 6.88 ppm
that correlates with C2 (143.1 ppm) in a 1H-13C HMQC
experiment (Chart 3). The unambiguous presence of the
1
indenylidene ligand is found from analysis of H-13C HMBC
data. In contrast to the observation for 6, the olefinic proton
correlates with the carbene carbon atom. Indeed, CR interacts
with aromatic proton H8 (δΗ ) 8.33), demonstrating that both
atoms were in the vicinity of no more than three bonds, whereas
it was six bonds for its alkenylcarbyne precursor 6. A related
(26) (a) Pirio, N.; Touchard, D.; Dixneuf, P. H.; Fettouhi, M.; Ouahab, L. Angew.
Chem. Int. Ed. Engl. 1992, 104, 651. (b) Peron, D.; Romero, A.; Dixneuf,
P. H. Organometallics 1995, 14, 3319.
(27) Asensio, A.; Buil, M. L.; Esteruelas, M. A.; On˜ate, E. Organometallics
2004, 23, 5787.
(28) (a) Jung, S.; Ilg, K.; Brandt, C. D.; Wolf, J.; Werner, H. Dalton Trans.
2002, 318. (b) Gonzalez-Herrero, P.; Weberndo¨rfer, B.; Ilg, K.; Wolf, J.;
Werner, H. Organometallics 2001, 20, 3672. (c) Stu¨er, W.; Wolf, J.; Werner,
H.; Schwab, P.; Schulz, M. Angew. Chem., Int. Ed. 1998, 37, 3421.
(25) Amoroso, D.; Snelgrove, J. L.; Conrad, J. C.; Drouin, S. D.; Yap, G. P.
A.; Fogg, D. E. AdV. Synth. Catal. 2002, 344, 757.
9
4082 J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006

Allenylidene-to-Indenylidene Rearrangement
A R T I C L E S
Scheme 3
revealed by the appearance of a new signal at 76.0 ppm in the
31P{1H} NMR spectrum. The 13C{1H} NMR spectrum shows
a lower-field doublet (2JP-C ) 19.2 Hz) at 327.5 ppm,
corresponding to the RutC carbon atom which, similarly to
the observation for 6, does not correlate with the olefinic proton
(δΗ ) 6.90) in a 1H-13C HMBC experiment. The special
structure of 11, bearing attached phenyl groups as substituents
on the alkenylcarbyne ligand, inhibits the rearrangement of the
allenylidene moiety into an indenylidene species. This was
corroborated by the fact that no new species was observed after
4 h at 0 °C. Furthermore, no catalytic activity was observed for
alkenylcarbyne derivative 11 on the RCM of 8 into 9 that was
promoted by the indenylidene complex 7 (Scheme 2).
3. Isolation of Ruthenium-Indenylidene Derivatives. Even
though the in situ-generated catalytic systems obtained by
addition of a strong acid to ruthenium-allenylidene derivatives
have exhibited high activity in ROMP of cyclooctene at room
temperature, it was necessary to operate at 0 °C in order to
perform catalytic reactions of less reactive substrates, as complex
7 progressively decomposes at room temperature under these
conditions with release of p-cymene and [HPCy3]OTf. Decom-
position of active species is probably accelerated by the presence
of an excess of acid. As we have discovered that triflic acid
acts only as a promoter of the allenylidene-indenylidene
rearrangement, once this transformation is completed, excess
acid could be removed without loss of catalytic activity.29 On
the basis of these observations, the isolation of indenylidene
derivatives that should allow acid-free catalytic reactions was
attempted (Scheme 3).
A garnet solution of 4a (300 mg, 0.34 mmol) in 5 mL of
CH2Cl2 at -60 °C was treated with 60 µL (0.67 mmol) of triflic
acid. The solution immediately changed to brown and became
dark violet after 2 h at -25 °C. The initial formation of the
alkenylcarbyne derivative 6 on protonation of 4a in equilibrium
is highly dependent on the pH of the solution. It was observed
that lowering the concentration of triflic acid, by simply
increasing the amount of solvent, inhibited the reaction and the
allenylidene starting material was recovered. Moreover, higher
concentrations of acid led to decomposition of subsequent
indenylidene species even at -30 °C. Therefore, an optimal
concentration of acid was found to be around 0.1 M and 2 equiv
relative to complex 4a.
The solution was passed through a cold basic alumina column
and eluted with CH2Cl2. The solvent was then evaporated below
-30 °C, and the residue precipitated in a mixture of cold diethyl
ether/pentane. Low-temperature NMR analysis of the isolated
brown solid shows signals corresponding to complex 7.30
Attempts to obtain monocrystals suitable for X-ray analysis were
unsuccessful. A similar experimental procedure was applied to
transform the corresponding allenylidene complexes [(η6-p-
cymene)RuCl(dCdCdCR2)(PCy3)]OTf {R ) iPr (12) and Ph-
(13)} into indenylidene derivatives [(η6-p-cymene)RuCl(ind)-
i
(PR3)]OTf {R ) Pr (14) and Ph (15)}.
It has been shown that replacement of one phosphine by an
NHC ligand in ruthenium-alkylidene initiators improves cata-
lytic activity. Following the experimental procedure developed
by Nolan,14g the synthesis of complex [(η6-p-cymene)RuCl(d
CdCdCPh2)(IMes)]OTf (4d) was accomplished. Attempts to
generate the related NHC-indenylidene complex by protonation
failed. The higher electron-donor properties of such ligands
relative to trialkylphosphines could disfavor the aromatic
electrophilic addition because of the enhanced electron density
of CR of the allenylidene moiety. However, in situ protonation
of 4d in the presence of cyclooctene results in the gelification
of the solution in 20 min at room temperature (Table 1, entry
8).
4. Olefin Metathesis Reactions Promoted by Acid-Free
Indenylidene-Ruthenium Complexes. It has been shown
above that in situ-generated indenylidene species are good
initiators for olefin metathesis. However, catalytic reactions have
to be carried out at 0 °C to prevent catalyst decomposition due
to the excess of acid. Isolated indenylidene complexes are able
to catalyze alkene metathesis reactions at higher temperatures.
Figure 3 shows a comparison between the catalytic performances
shown by isolated and in situ-generated indenylidene initiators
7 at room temperature. Both systems display high activity in
RCM of diene 8 with low catalyst loading (0.5 mol %). In situ-
generated systems display higher initial activity depending on
acid concentration. However, conversion is abruptly stopped,
probably due to catalyst decomposition. Isolated catalyst 7
presents lower initial performance but it was maintained in the
course of the reaction, reaching almost complete conversion in
10 min.
Catalytic activities for ROMP of cyclooctene of indenylidene
isolated complexes 7 (PCy3), 14 (PiPr3), and 15 (PPh3) were
studied. Chlorobenzene revealed a better performance than CH2-
Cl2 or toluene, while poorer conversion was observed in THF
or diethyl ether. Polymerization results are compiled in Table
2. Complex 7 polymerizes cyclooctene with an extremely low
After the formation of complex 7 is accomplished, it is
mandatory to neutralize the reaction mixture at low temperature.
(29) Previously it has been shown that addition of acid to Grubbs-type systems
accelerates the rate of the catalytic reaction. In these cases, acid promotes
phosphine decoordination, liberating the 14-electron active species, but does
not affect propagating steps. (a) Reference 22. (b) Lynn, D. M.; Mohr, B.;
Grubbs, R. H.; Henling, L. M.; Day, M. W. J. Am. Chem. Soc. 2000, 122,
6601.
(30) Due to instability of ruthenium-indenylidene complexes at room temper-
ature, satisfactory elemental analysis could not be obtained.
9
J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006 4083

A R T I C L E S
Castarlenas et al.
decrease of viscosity was observed and no polymer was
recovered after treatment of samples, indicating that complex
7 acts also as a depolymerization catalyst.32 Complex 7 is less
active in the ROMP of oxygen-containing monomers like epoxy-
5-cyclooctene and cyclooctenylphenyl ester, probably due to
the coordination of the polar groups to propagating species.
Isolated indenylidene derivatives are able to catalyze RCM
and enyne metathesis reactions of a very large set of products
at room temperature (Table 4). An impressive performance was
found for RCM of diene 8, which was completed in only 1
min. To know the applicability of this catalyst for RCM of more
complicated substrates, which is of industrial interest, more
sterically demanding substrates were tested. In the cases of γ-
(16) and â-methyl (17)-substituted diallyltosylamide, both are
smoothly cyclized but 16 h is necessary to transform 17 into
18 (entries 2 and 3).
Figure 3. Comparison of catalytic activity in the RCM of 8 between in
situ acid-generated and isolated catalysts 7 at room temperature.
Catalyst 7 is also active for the rearrangement of enynes into
alkenylcycloalkenes by enyne RCM. Transformation of com-
pound 19 into 20 can be used as a simple test to quantify catalyst
activity. Only 90 min was necessary to reach 93% yield (entry
4). This catalyst opens access to new compounds of added value
and with atom economy. Polyfluorenes are organic electrolu-
minescent materials that have been applied to devices in
photonics and optoelectronics.33 The allyl propargyl fluorene
derivative 21 was transformed with catalyst 7 into diene 22 that
has potential as a monomer block for the synthesis of polymer-
supported chromophores. Different terpenoids with flavor inter-
est, such as compounds derived from (-)-myrtenal (24), (-)-
menthone (26), and citral (28), were formed as well in better
yield under mild conditions as compared to previous attempts
(entries 6-8).34
5. New Allenylidene-Metal Precatalyst. The alkene me-
tathesis catalytic activity observed for allenylidene precatalysts
motivated us to undertake modifications of the γ-substituents
on the allenylidene moiety. The synthesis of various allenylidene
complexes was attempted by reaction of the cationic complex
[(η6-p-cymene)RuCl(PCy3)]OTf (29) with propargyl alcohols
in CH2Cl2. Treatment of 29 with 2-phenyl-3-butyn-2-ol led to
the allenylidene derivative [(η6-p-cymene)RuCl{)CdCdC(Me)-
Ph}(PCy3)]OTf (30), which was isolated at low temperature.
The reaction carried out with 1-phenyl-2-butyn-1-ol and 2-meth-
yl-3-butyn-2-ol gave rise to several unidentified products. The
more interesting features observed in the 13C{1H} NMR
spectrum of 30 are two singlets at 288.3 and 169.4 ppm,
corresponding to CR and Câ, respectively, of the allenylidene
moiety. A signal corresponding to a methyl group appears at
Table 2. Cyclooctene Polymerization Catalyzed by Isolated
Indenylidene Complexes at Room Temperaturea
3
yield
(%)
10-
×
TOF
1
entry
catalyst
ratiob
time
Mn
PDI
(min-
)
1
2
3
4
5
7
7
7
14
15
10 000
30 000
100 000
10 000
10 000
1 min
3 min
16 h
2 min
16 h
99
92
32
93
42
549
754
645
621
387
1.31
1.35
1.61
1.41
1.53
9 900
9 200
33
4 650
4
a 4.5 × 10-3 mol of cyclooctene in 2.5 mL of PhCl. b [monomer]/[Ru].
catalyst loading (1:30 000) in only 5 min, displaying an im-
pressive TOF of 9200 min-1 (entry 2). Activity of 7 diminished
when the monomer/ruthenium ratio was increased to 100 000,
probably due to decomposition of catalyst by monomer impuri-
ties. Indenylidene derivative 14 is a good initiator and presents
a slightly lower activity than that of 7. Poorer conversions are
reached with derivative 15, showing that both electron-donor
ability and bulkiness of the phosphine ligand play key roles.
Catalytic activity of complex 7 was evaluated in ROMP of
less reactive monomers. It was found that, with Schrock-type
initiators [W(dCHtBu)(OtBu)2(NAr)], polymerization of cy-
clopentene takes place at temperatures below -40 °C ([catalyst]:
[monomer] ) 1:200, 4 h, 95% conversion).31 At this temper-
ature, complex 7 was able to polymerize in 1 h up to 98% of
cyclopentene with an extremely low loading of catalyst (1:
10 000), showing even better activity (Table 3, entry 1).
However, experiments carried out at room temperature gave
rise to initial gelification of the sample, but a progressive
Table 3. ROMP of Unstrained Monomers Mediated by 7
a 2.5 mL of PhCl. [monomer]/[Ru] ) 10 000. b 2.5 mL of PhCl. [monomer]/[Ru] ) 1000.
9
4084 J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006

Allenylidene-to-Indenylidene Rearrangement
A R T I C L E S
Table 4. RCM and Enyne Metathesis Reactions Promoted by 7a
a 2.5 mL of PhCl. [monomer]/[Ru] ) 50 at room temperature.
33.3 ppm, which correlates with the methyl group (δΗ ) 2.49
ppm) in the 1H-13C HMQC experiment, and discards a
vinylvinylidene species.35 Moreover, a strong allenylidene IR
gelification of sample was observed in 5 min, but only 63% of
polymer was recovered.
band was observed at 1957 cm-1
.
It was found that replacing a phenyl group with a methyl
group on the allenylidene ligand of 4a resulted in an increase
of the catalytic activity of 30 (Figure 4). After 3 h at room
temperature, substrates 8 and 19 were transformed into 9 and
20 in 92 and 85% respectively, whereas catalyst 4a attained 60
and 70% of final products under the same conditions. However,
the performance of catalyst 30 did not reach that displayed by
indenylidene 7.
Catalyst 30 presents good activity for ROMP reactions as
well (Table 5). Cyclopentene was polymerized at -40 °C,
showing a TOF value of 150 min-1, which is close to that
observed for 7 (163 min-1). In the case of cyclooctene, complete
(31) (a) Dounis, P.; Feast, W. J.; Kenwright, A. M. Polymer 1995, 36, 2787.
(b) Schrock, R. R.; Yap, K. B.; Yang, D. C.; Sitzmann, H.; Sita, L. R.;
Bazan, G. C. Macromolecules 1989, 22, 3191.
(32) Polymerization of cyclopentene at -40 °C must be quenched by addition
of ethyl vinyl ether and CHCl3 at low temperature. The resulting mixture
has to be kept stirring for 1 h at -40 °C and then be allowed to slowly
reach room temperature.
(33) (a) Li, J. Y.; Ziegler, A.; Wegner, G. Chem. Eur. J. 2005, 11, 4450. (b)
Wong, W. Y. Coord. Chem. ReV. 2005, 249, 971. (c) Setayesh, S.;
Grimsdale, A. C.; Weil, T.; Enkelmann V.; Mu¨llen, K.; Meghdadi, F.; List,
E. J. W.; Leising, G. J. Am. Chem. Soc. 2001, 123, 946.
(34) Le Noˆtre, J.; Bruneau, C.; Dixneuf, P. Eur. J. Org. Chem. 2002, 3816.
(35) (a) Bustelo, E.; Jime´nez-Tenorio, M.; Puerta, M. C.; Valerga, P. Organo-
metallics 1999, 18, 4563. (b) Cadierno, V.; Gamasa, M. P.; Gimeno, J.;
Gonza´lez-Cueva, M.; Lastra, E.; Borge, J.; Garc´ıa-Granda, S.; Pe´rez-
Carren˜o, E. Organometallics 1996, 15, 2137.
Figure 4. Compared catalytic activity of 4a (red squares), 7 (yellow
triangles), and 30 (blue diamonds) on the transformation of 8 and 19.
9
J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006 4085

A R T I C L E S
Castarlenas et al.
Table 5. ROMP Reactions of Cyclic Alkenes Catalyzed by 30a
a 2.5 mL of PhCl. [monomer]/[Ru] ) 10000.
Scheme 4
These observations suggest the following mechanism (Figure
5). The first step is the rearrangement of the allenylidene moiety
into an indenylidene species. Subsequent decoordination of the
η6-bound arene ligand generates an unsaturated species that
could be stabilized by the counterion. The resulting 14-electron
initiators could enter into a Chauvin cycle for promoting olefin
metathesis reactions.
First Step: Rearrangement. The allenylidene ligand is
transformed into an indenylidene group via an aromatic elec-
trophilic substitution which is favored by the electrophilicity
of the CR carbon atom. Electron-releasing ancillary ligand L
should disfavor this rearrangement and thus the catalyst precur-
sor formation. This inhibition to form the indenylidene group
accounts for the lower catalytic activity found for complex 4d
that bears an electron-releasing imidazolylidene ligand. Addition
of acid may favor this step due to the formation of alkenylcar-
byne species which possesses a more electrophilic carbon atom
than the allenylidene moiety.
Complex 30 may rearrange to a novel methyl-indenylidene
intermediate as previously described for its phenyl-phenyl-
allenylidene counterpart. Addition of triflic acid to CD2Cl2
solutions of 30 at -40 °C gave rise to the formation of the
alkenylcarbyne complex [(η6-p-cymene)RuCl{tC-CHdC(Me)-
Ph}(PCy3)](OTf)2 (31) (Scheme 4) as indicated by low-
temperature NMR experiments. The most notable feature of 31
is the RutC signal that appears at 332.0 ppp in the 13C{1H}
NMR spectrum. That signal does not correlate with the olefinic
proton (δΗ ) 7.12), and a typical five-proton phenyl group is
1
observed in the H NMR spectrum. However, warming the
Second Step: Generation of Active Species. As discussed
previously, decoordination of η6-bound arene is the most
plausible way to generate species that are coordinatively
unsaturated. It is obvious that the stronger steric interaction
between the arene ligand and the indenylidene group, with
respect to that of the allenylidene group, may favor the arene
decoordination. An increase in the stability of the arene-
ruthenium bond causes a decrease in catalytic performance from
4a (p-cymene) to 4e (tetramethylbenzene) and 4f (hexameth-
ylbenzene). Decoordination of the p-cymene ligand generates
a highly unsaturated 12-electron species that is likely stabilized
by the coordination ability of the triflate ligand. It explains the
differences observed in catalytic activity on counterion variation.13b
These intermediates must be protected by an ancillary ligand
to prevent deactivation by dimerization of the carbene ligand.
Thus, bulky ligands such as NHC may favor this step whereas
phosphines need to have a large cone angle.
Third Step: Propagation. Once ruthenium-indenylidene
p-cymene-free species are generated, they can enter into the
catalytic cycle. Metallacyclobutane stabilization is favored by
the electron-releasing capability of the ancillary ligands. Thus,
NHC is the most favorable ligand and the less-electron-donating
PPh3 is the least favorable group. Based on experimental results,
the best compromise for the overall activity is provided by PCy3,
which has electron-donating capability between those of imi-
dazolylidene and PPh3 groups.
solution to -20 °C led to a mixture of several products that
could not be characterized. Complex 31 presents very low alkene
metathesis catalytic activity, similar to the other alkenylcarbyne
derivatives 6 and 11.
6. Activation Mechanism for Allenylidene Precatalysts.
The ruthenium-allenylidene and precatalysts 4 and 7 are ionic
18-electron species. To become an active catalytic species they
must be coordinatively unsaturated in order to allow a substrate
to enter the coordination sphere of the metal. Usually catalytic
species have 16 or even 14 electrons for some olefin metathesis
initiators. To generate vacant sites a ligand must decoordinate
from 7. There are two candidates, the phosphine or the η6-bound
p-cymene ligand. Grubbs and co-workers proposed that deco-
ordination of one phosphine is the activation step for catalysts
1 and 2.9 In addition, acid treatment of Grubbs catalysts favors
decoordination of the phosphine. In that case an electron-
releasing ligand remains bound to the ruthenium atom, stabiliz-
ing the metallacycle intermediate.
On the hypothesis that the phosphine ligand decoordinates
from our initiators 7, no other electron-releasing ligand would
stabilize the formation of a metallacycle intermediate. The nature
of the phosphine (PCy3, PiPr3, and PPh3) strongly modifies the
catalytic activity of indenylidene complexes and thus supports
the hypothesis that the presence of a phosphine ligand is
essential in the propagation species. Moreover, it has been
previously described that the p-cymene ligand is a weak ligand
that could be easily released. Indeed, previous activation of
allenylidene catalyst by UV light improves catalytic activity
because of decoordination of an arene ligand.16b,17b In the
catalytic transformation 8 f 9 by complexes 4 and 7, the free
p-cymene is always observed in the initial step of the reaction
Conclusion
By contrast to previous works showing that (arene)ruthe-
nium-allenylidene catalysts are active catalysts for alkene
metathesis reactions, we have now observed the direct rear-
rangement of the allenylidene-metal complex into an inde-
1
by H NMR spectroscopy and gas chromatography.
9
4086 J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006

Allenylidene-to-Indenylidene Rearrangement
A R T I C L E S
Figure 5. Activation mechanism for allenylidene precatalysts.
K): δ 284.1 (br, RudC), 188.7 (s, RudCdC), 173.2 {s, Ru-C(Imes)},
160.5 (s, RudCdCdC), 141.6, 141.4, 140.7, 137.2, and 137.1 (all s,
Cq), 134.2, 133.1, 132.2, 130.5, 129.8, 129.6, and 128.3 (s, CPh + Imes),
126.2 and 125.2 (both s, Cp-cymene), 120.2 (q, JC-F ) 319.8 Hz, CF3),
105.4, 104.2, 94.2, and 92.4 (all s, Cp-cymene), 31.5 (s, CHPr), 23.9,
23.0, 21.0, 20.8, 18.6, 18.4, and 17.2 (all s, CH3).
nylidene-metal derivative. This rearrangement was previously
questioned but never directly observed. It is now established
that this acid-promoted reaction involves the electrophilic
alkenylcarbyne-ruthenium intermediate formation. The above
results show that in situ-generated (arene)ruthenium-inde-
nylidene intermediates are extremely active in ring-opening
metathesis polymerization reactions and that the isolated deriva-
tives show even improved catalytic activity for the ring-closing
metathesis of a variety of dienes and enynes.
i
Preparation of [(η6-p-Cymene)RuCl(tCsCHdCPh2)(PCy3)]-
(OTf)2 (6). A garnet solution of 4a (40 mg, 0.045 mmol) in 0.5 mL of
CD2Cl2 in an NMR tube under an argon atmosphere at 233 K was
treated with 5 µL (0.056 mmol) of triflic acid. The color changed
immediately to dark orange, and after the NMR tube was sealed under
Experimental Section
1
an argon atmosphere, measurements were made. H NMR (CD2Cl2,
All reactions were carried out with rigorous exclusion of air using
Schlenk tube techniques. Organic solvents were dried by standard
procedures and distilled under argon prior to use. Starting complexes
[(η6-p-cymene)RuCl(PCy3)][X],13b [(η6-p-cymene)RuCl(dCdCdCAr2)-
(PR3)][X],13b and (η6-p-cymene)RuCl2(IMes)14g and organic products
16,13a 17,10d and (19, 23, 25, 27)34 were synthesized as previously
described in the literature. Cyclooctene and cyclopentene were distilled
from powdered NaOH and stored under argon with 4-Å molecular
233 K): δ 8.12 (vt, JH-H ) 7.0 Hz, 2 H, Hm-Ph), 7.8-7.3 (m, 6 H,
HPh), 7.05 (s, 1 H, RutCsCHd), 6.92 (vt, JH-H ) 7.5 Hz, 2 H, Hm-Ph),
6.75 and 6.61 (both d, JH-H ) 6.0 Hz, 4 H, η6-p-cymene), 2.9-2.6 (m,
4 H, iPr and PCH), 2.28 (s, 3 H, CH3), 2.1-0.9 (m, 36 H, Cy and iPr).
13C{1H} NMR + DEPT, HMQC and HMBC (CD2Cl2, 233 K): δ 328.1
(d, JC-P ) 11 Hz, RutC), 193.2 (s, CHdCPh2), 140.5 and 137.6 (both
s, Cipso-Ph), 136.0, 134.8, 134.2, 130.3, 129.4, and 127.8 (all s, Cph),
130.5 (s, RutCsCHd), 128.2 and 125.8 (both s, Cipso-p-cymene), 120.4
(q, JC-F ) 320.0 Hz, CF3), 111.8, 108.7 (both s, Cp-cymene), 33.3 (s,
1
sieves. H NMR spectra were recorded at 300 MHz on a Bruker AM
300 WB spectrometer, and chemical shifts are expressed in parts per
million (ppm) downfield from Me4Si. 13C{1H} NMR spectra were
recorded at 75.4 MHz, and chemical shifts are expressed in ppm
downfield from Me4Si. 31P{1H}NMR spectra were recorded at 121.4
MHz, and chemical shifts are expressed in ppm downfield from 85%
H3PO4. Coupling constants, J, are given in hertz. Samples for IR spectra
were prepared as Nujol mulls on polyethylene sheets.
CHPr), 31-24 (br, Cy), 25.1, 22.2 (s, CH3- Pr), 19.9 (s, CH3). 31P{1H}
NMR (CD2Cl2, 233 K): δ 78.6 (s).
i
i
Preparation of [(η6-p-Cymene)RuCl(ind)(PCy3)]OTf (7). A garnet
solution of 4a (300 mg, 0.34 mmol) in 5 mL of CH2Cl2 at 213 K was
treated with 60 µL (0.67 mmol) of triflic acid. The solution immediately
changed to brown and became dark violet after 2 h at 248 K. The
solution was then cooled to 193 K and, after addition of 15 mL of
CH2Cl2, was stirred with 4 g of aluminum oxide, activated basic,
Brockmann I for 15 min. The product was filtered off, and the alumina
was washed two times with 10 mL of CH2Cl2. The resulting dark purple
solution was evaporated to dryness below 243 K (it may take a long
time). The bright brown-violet solid was washed three times at low
temperature with a mixture of pentane (5 mL)/diethyl ether (1 mL)
and dried under vacuum. A brown solid was obtained (250 mg, 83%
yield). IR (Nujol, cm-1): νa(SO3) 1261 (s); νa(CF3) 1146 (s); νs(SO3)
1032 (s); δa(SO3) 639 (s).1H NMR (CD2Cl2, 233 K): δ 8.33 (m, 1 H,
Preparation of [(η6-p-Cymene)RuCl(dCdCdCPh2)(IMes)][OTf]
(4d). A light-protected orange solution of (η6-p-cymene)RuCl2(IMes)
(500 mg, 0.82 mmol) in 20 mL of CH2Cl2 was treated with 211 mg
(0.82 mmol) of AgOTf and stirred for 30 min. The resulting violet
suspension was filtered through Celite, and 190 mg (0.91 mmol) of
1,1-diphenyl-2-propyn-1-ol was added. After 4 h at room temperature,
the resulting dark red solution was evaporated to dryness, washed three
times with a mixture of pentane (5 mL)/diethyl ether (3 mL), and then
dried under vacuum (485 mg, 65% yield). IR (Nujol, cm-1): ν(Cd
CdC) 1968, νa(SO3) 1261 (s); νa(CF3) 1148 (s); νs(SO3) 1027 (s); δa-
1
H8-ind), 7.84 (d, JH-H ) 7.5 Hz, 2 H, Ho-Ph), 7.75 (t, JH-H ) 7.5 Hz,
(SO3) 638 (s). H NMR (CDCl3, 293 K): δ 7.1-7.9 (m, 16 H, HPh),
5.67, 5.61, 5.37, and 5.04 (all d, JH-H ) 9.6 Hz, 4 H, η6-p-cymene),
1 H, Hp-Ph), 7.60 (vt, JH-H ) 7.5 Hz, 2 H, Hm-Ph), 7.42 (m, 2 H, H7-ind
and H6-ind), 7.13 (m, 1 H, H5-ind), 6.88 (s, 1 H, RudCsCHd), 6.36,
i
3.2 (m, 1 H, Pr), 2.5-1.2 (27 H, CH3). 13C{1H} NMR (CDCl3, 293
9
J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006 4087

A R T I C L E S
Castarlenas et al.
6.31, 6.19, and 6.15 (all d, 4 H, JH-H ) 6.0 Hz, η6-p-cymene), 2.83
(m, 1 H, iPr), 2.78 (m, 3 H, PCH), 2.31 (s, 3 H, CH3), 2.1-0.9 (m, 36
Preparation of 9-(Allyloxy)-9-ethynyl-9H-fluorene (21). To a
solution of NaH (210 mg, 90% purity, 8.33 mmol) in 40 mL of a 1:1
mixture of DMSO and THF at 0 °C was added 1.43 g (6.93 mmol) of
9-ethynyl-9H-fluoren-9-ol. After the mixture was stirred for 15 min at
0 °C and 45 min at room temperature, 0.7 mL (8.33 mmol) of allyl
bromide was added, and the mixture was kept stirring overnight. The
mixture was then hydrolyzed with water, extracted with heptane, dried
with MgSO4, and concentrated under vacuum. Further purification by
column chromatography (heptane-diethyl ether 8:2) yielded a yellow
i
H, Cy and Pr). 13C{1H} NMR + DEPT, HMQC, and HMBC (CD2-
Cl2, 233 K): δ 334.1 (d, JC-P ) 10 Hz, RudC), 154.6 (s, C3-ind), 146.8
(s, C9-ind), 143.1 (d, JC-P ) 2 Hz, C2-ind), 136.5 (s, C4-ind), 134.7 (s,
C
C
C
7-ind), 133.4 (s, C8-ind), 132.7 (s, C6-ind), 132.5 (s, Cp-Ph), 131.7 (s,
ipso-Ph), 130.0 (s, Cm-Ph), 127.8 (s, Co-Ph), 126.3 and 125.3 (both s,
ipso-p-cymene), 121.2 (s, C5-ind), 120.4 (q, JC-F ) 320.0 Hz, CF3), 103.6
i
and 99.7 (both s, Cp-cymene), 33.8 (s, CHPr); 30-24 (br, Cy); 24.2 and
1
22.8 (both s, CH3- Pr); 19.6 (s, CH3). 31P{1H} NMR (CD2Cl2, 233 K):
i
oil (1.7 g, 98%). H NMR (CDCl3, 293 K): δ 7.8-7.3 (m, 8 H, Ph),
5.85 (m, 1 H, CHdCH2), 5.14 (m, 2 H, CHdCH2), 3.72 (m, 2 H, CH2-
CHdCH2), 2.53 (s, 1 H, sCtCH). 13C{1H} NMR (CDCl3, 293 K): δ
145.1 and 140.3 (Cipso-Ph), 135,2 (CHdCH2), 130.2, 127.3, 125.3,
and 120.9 (CPh), 116.2 (OCH2), 82.3 and 72.8 (CtCH).
δ 48.3 (s).
Preparation of [(η6-p-Cymene)RuCl{dCdCdC(C12H8)}(PCy3)]-
[OTf] (10). An orange solution of 29 (300 mg, 0.43 mmol) in 10 mL
of CH2Cl2 at 253 K was treated with 96 mg (0.47 mmol) of 9-ethynyl-
9-fluorenol. The solution was kept stirring for 1 h, and then the solvent
was removed under vacuum at 253 K. The resulting violet solid was
washed with a mixture of pentane (5 mL)/diethyl ether (1 mL) and
dried under vacuum. IR (Nujol, cm-1): ν(CdCdC) 1963, νa(SO3) 1265
(s); νa(CF3) 1153 (s); νs(SO3) 1031 (s); δa(SO3) 637 (s). 1H NMR (CD2-
Cl2, 243 K): δ 7.7-7.1 (m, 8 H, HPh), 6.74, 6.68, 6.21, 6.13 (4 H,
η6-p-cymene), 2.62 (m, 1 H, iPr), 2.32 (m, 3 H, PCH), 2.1-0.9 (m, 36
H, Cy and CH3). 13C{1H} NMR + DEPT, HMQC and HMBC (CD2-
Cl2, 243 K): δ 291.4 (d, JC-P ) 21.9 Hz, RudC), 195.5 (s, RudCd
C), 159.8 (s, RudCdCdC), 146.8, 146.1, 141.5, and 139.3 (all s, Cq),
135.5, 130.1, 129.7, and 128.6 (s, CPh), 122.0 and 120.3 (both s,
Preparation of 13-Vinyl-9,9′-(2,5-dihydrofuran)-9H-fluorene (22).
A solution of 7 (4 mg, 0.042 mmol) in 3 mL of chlorobenzene under
an argon atmosphere was treated with 21 (51 mg, 0,21 mmol), and the
mixture was kept stirring for 16 h at room temperature. The solution
was then evaporated, and the crude product was purified by column
1
chromatography (heptane-diethyl ether 8:2) (51 mg, 98% yield). H
NMR (CDCl3, 293 K): δ 7.9-7.1 (m, 8 H, Ph), 6.34 (s, 1 H, OCH2s
CHdC), 6.03 (dd, JH-H ) 10.4 and 6.9 Hz, 1 H, CHdCH2), 5.02 (s,
2H, OCH2), 4.67 (d, JH-H ) 9.9 Hz, 1 H, CHdCH2), 4.46 (d, JH-H
10.4 Hz, 1 H, CHdCH2).
)
Preparation of [(η6-p-Cymene)RuCl{dCdCdC(Me)Ph}(PCy3)]-
OTf (30). An orange solution of 29 (200 mg, 0.284 mmol) in 10 mL
of CH2Cl2 at room temperature was treated with 50 mg (0.340 mmol)
of 2-phenyl-3-butyn-2-ol. The solution was kept only 1 min at room
temperature and then cooled to 253 K for 2 h. The brown solution was
evaporated to dryness, washed three times with pentane (6 mL)/ether
(1 mL) below 253 K, and dried in a vacuum. IR (Nujol, cm-1): ν-
(CdCdC) 1957, νa(SO3) 1263 (s); νa(CF3) 1148 (s); νs(SO3) 1029 (s);
δa(SO3) 638 (s). 1H NMR (CD2Cl2, 243 K): δ 8.23 (d, JH-H ) 7.4 Hz,
2 H, Ho-Ph), 7.82 (t, JH-H ) 7.4 Hz, 1 H, Hp-Ph), 7.53 (vt, JH-H ) 7.4
Hz, 2 H, Hp-Ph), 6.71 and 6.65 (both d, JH-H ) 6.0 Hz, 2 H, η6-p-
cymene), 6.11 and 6.07 (both d, JH-H ) 6.6 Hz, 2 H, η6-p-cymene),
Cp-cymene), 120.2 (q, JC-F ) 319.8 Hz, CF3), 108.5, 103.0, 96.2, and
i
i
98.9 (all s, Cp-cymene), 32.2 (s, CHPr); 24.3 and 22.6 (both s, CH3- Pr);
19.2 (s, CH3). 31P{1H} NMR (CD2Cl2, 243 K): δ 61.1 (s).
Preparation of [(η6-p-Cymene)RuCl(tCsCHdC(C12H8)(PCy3)]-
OTf (11). A violet solution of 10 (50 mg, 0.06 mmol) in 0.5 mL of
CD2Cl2 in an NMR tube under an argon atmosphere at 233 K was
1
treated with 15 µL (0.17 mmol) of HSO3CF3. H NMR (CD2Cl2, 233
K): δ 8.2-7.1 (m, 12 H, HPh, η6-p-cymene), 6.90 (s, RutCCH), 2.81
i
(m, 1 H, Pr), 2.31 (m, 3 H, PCH), 2.1-0.9 (m, 39 H, Cy and CH3).
13C{1H} NMR, HMQC, and HMBC (CD2Cl2, 233 K): δ 327.5 (d, JC-P
) 19.2 Hz, RutC), 182.6 (s, RutCsCHdC), 140.3, 139.3, 138.2,
and 135.8 (all s, Cq), 132.1, 131.6, 131.2, 130.4, 129.6, 128.8, 128.2,
and 127.6 (s, CPh), 125.2 and 123.3 (both s, Cp-cymene), 120.2 (q, JC-F
) 320.2 Hz, CF3), 115.2, 113.8, 112.4, and 109.3 (all s, Cp-cymene),
i
2.85 (m, 1 H, Pr), 2.66 (m, 3 H, PCH), 2.49 {s, 3 H, dC(CH3)Ph},
i
2.23 (s, 3 H, CH3), 2.1-0.9 (m, 36 H, Cy and Pr). 13C{1H} NMR +
DEPT, HMQC, and HMBC (CD2Cl2, 243 K): δ 288.3 (d, JC-P ) 20
Hz, RudC), 169.4 (s, RudCdC), 141.5 and 135.1 (both s, Cquat), 130.5,
129.5, and 128.2 (all s, CPh), 122.7 and 118.4 (both s, Cipso-p-cymene),
31.0 (s, CHPr); 25.6 and 24.2 (both s, CH3- Pr); 20.4 (s, CH3). 31P{1H}
NMR (CD2Cl2, 233 K): δ 76.0 (s).
i
i
120.6 (q, JC-F ) 320.0 Hz, CF3), 107.1, 102.3, 95.5, and 94.9 (all s,
Preparation of [(η6-p-Cymene)RuCl(ind)(PiPr3)]OTf (14). This
complex was prepared as described for 7 starting from 300 mg (0.39
mmol) of 12 and 60 µL (0.67 mmol) of triflic acid (250 mg, 83% yield).
1H NMR (CD2Cl2, 243 K): δ 8.21 (m, 1 H, H8-ind), 8.1-6.9 (8 H,
Ph), 6.92 (s, 1 H, H2-ind), 6.39, 6.30, 6.18, and 6.11 (all d, 4 H, JH-H
) 6.0 Hz, η6-p-cymene), 2.79 (m, 1 H, iPr), 2.2 (m, 6 H, iPr, CH3), 1.9
(m, 24 H, iPr). 13C{1H} NMR + DEPT (CD2Cl2, 243 K): δ 333.2 (br,
RudC), 155.0 (s, C3-ind), 147.0 (s, C9-ind), 142.5 (s, C2-ind), 136.6 (s,
i
C
p-cymene), 33.3 (s, C(Ph)CH3), 32.3 (s, CHPr), 29.5-24.5 (br, Cy), 24.1,
19.8, and 18.5 (all s, CH3). 31P{1H} NMR (CD2Cl2, 243 K): δ 57.6
(s).
Preparation of [RuCl(η6-p-Cymene){tCsCHdC(Me)Ph}(PCy3)]-
(OTf)2 (31). An orange solution of 30 (40 mg, 0.048 mmol) in 0.5 mL
of CD2Cl2 in an NMR tube under an argon atmosphere at 213 K was
1
treated with 14 µL (0.156 mmol) of triflic acid. H NMR (CD2Cl2,
243 K): δ 8.13 (d, JH-H ) 7.0 Hz, 2 H, Ho-Ph), 7.91 (t, JH-H ) 7.0
Hz, 1 H, Hp-Ph), 7.6-7.3 (m, 6 H, η6-p-cymene, Hp-Ph), 7.12 (s, 1 H,
RutCCH), 3.11 {s, 3 H, dC(CH3)Ph}, 2.82 (m, 1 H, iPr), 2.54 (m, 3
H, PCH), 2.23 (s, 3 H, CH3), 2.1-0.9 (m, 36 H, Cy and iPr). 13C{1H}
NMR + DEPT, HMQC, and HMBC (75.4 MHz, CD2Cl2, 243 K): δ
332.0 (br, RutC), 195.6 (s, CHdC(Me)Ph), 140.5 and 138.3 (s,
C4-ind), 133.4 (s, C7-ind), 132.6 (s, C8-ind), 131.2-120.3 (CPh, C5-ind,
C6-ind, CF3), 121.0 and 116.9 (both s, Cp-cymene), 104.8, 101.2, 99.8,
i
and 97.2 (all s, Cp-cymene), 31.4 (s, CHPr); 25.9 (s, PCH), 22.2, 19.3,
and 18.9 (all s, CH3). 31P{1H} NMR (CD2Cl2, 243 K): δ 54.2 (s).
Preparation of [(η6-p-Cymene)RuCl(ind)(PPh3)]OTf (15). This
complex was prepared as described for 7 starting from 300 mg (0.36
mmol) of 13 and 60 µL (0.67 mmol) of triflic acid (270 mg, 90% yield).
1H NMR (CD2Cl2, 243 K): δ 8.13 (m, 1 H, H8-ind), 8.1-6.9 (27 H,
Cipso-Ph), 131.6, 130.5, and 130.1 (all s, CPh), 126.6 (s, RutCsCHd),
126.0 and 125.3 (both s, Cipso-p-cymene), 120.2 (q, JC-F ) 318.3 Hz,
CF3), 121.6,120.8, 118.6, and 117.4 (all s, Cp-cymene), 33.7 (s, C(Ph)-
Ph, η6-p-cymene), 6.41 (s, 1 H, H2-ind), 2.59 (m, 1 H, Pr), 2.10 (s, 3
i
i
CH3), 33.1 (s, CHPr), 29.5-25.5 (br, Cy), 22.1, 20.2, 20.0 (all s, CH3).
31P{1H} NMR (CD2Cl2, 243 K): δ 75.7 (s).
H, CH3), 1.9 (br, 6 H, Pr). 13C{1H} NMR + DEPT, HMQC, and
i
HMBC (CD2Cl2, 243 K): δ 336.1 (d, JC-P ) 8 Hz, RudC), 154.1 (s,
General Procedure for the Polymerization of Cycloolefins Using
in Situ-Prepared Catalyst. Complex 4a (8 mg, 9 mmol) was dissolved
in PhCl (0.5 mL) at 253 K, and 4 µL (45 mmol) of triflic acid was
added. After 30 min at this temperature, the desired amount of freshly
prepared catalyst was transferred to a vessel at the chosen temperature
containing PhCl (2.5 mL) and monomer (500 mg; 4.5 mmol of
C3-ind), 142.9 (s, C2-ind), 142.0 and 137.3 (both s, C4-ind and C9-ind),
132.3 (s, C7-ind), 131.8 (s, C8-ind), 129.8-120.3 (CPh, C5-ind, C6-ind
,
i
C
p-cymene, CF3), 114.2, 113.8 (both s, Cp-cymene), 32.5 (s, CHPr); 25.1
and 23.6 (both s, CH3- Pr); 19.4 (s, CH3). 31P{1H} NMR (CD2Cl2, 243
K): δ 42.1 (s).
i
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4088 J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006

Allenylidene-to-Indenylidene Rearrangement
A R T I C L E S
cyclooctene, 1.46 M; 7.3 mmol of cyclopentene, 2.33 M). The same
procedure was carried out with isolated complex 7 (9 mmol) in PhCl
(2.5 mL) at room temperature. The resulting viscous mixture was
dissolved with CHCl3 containing 0.1% of 2,6-di-tert-butyl-4-meth-
ylphenol (BHT; 20 mL) and vinyl ethyl ether (0.3 mL). This solution
was poured into methanol (300 mL) to precipitate the polymer, which
was collected by filtration, dried under vacuum, and characterized by
1H and 13C NMR. Average molecular weights were determined using
gel permeation chromatography (GPC) calibrated with polystyrene
standards.
) 50) in dry PhCl (2.5 mL). The progress of the reaction was monitored
by gas chromatography. After evaporation of PhCl, the products were
isolated by column chromatography on silica gel using mixtures of
heptane and diethyl ether as eluents and then characterized by 1H, 13
C
NMR and GC/MS analysis.
Acknowledgment. The authors are grateful to the European
Union (Network Polycat HPRN-CT-2000-00010) and Bretagne
region (PRIR catalyse) for support and to the “Marie Curie”
Fellowship Programme for postdoctoral contract to R.C.
General Procedure for the Ring-Closing Metathesis of Dienes
or Enynes Using Isolated Catalyst 7. The substrate (0.56 mmol) was
added to a solution of complex 7 (10 mg, 11.25 × 10-2 mmol, S/Ru
JA0579762
9
J. AM. CHEM. SOC. VOL. 128, NO. 12, 2006 4089