Intramolecular cyclization of ruthenium vinylidene complexes with a tethering vinyl group: Facile cleavage and reconstruction of the C-C double bond

Article abstract of DOI:10.1021/ja074951p

Protonation of ruthenium acetylide complexes [M]- *C≡*CCPh₂CH₂CH≡CH₂ (2a, [M] = (η⁵-C₅H₅)(P(OPh)₃) (PPh₃)Ru; 2a′, [M] = (η⁵-C₅H ₅)(dppp)Ru; *C = ¹³C-labeled carbon atom) with HBF₄ in ether produces [[M]=*C=CHCH₂CPh ₂*CH=CH₂][BF₄] (4, 4′) exclusively via a metathesis process of the terminal vinyl group with the *C=*C of the resulting vinylidene group. For 4 in methanol, bond reconstruction of the two labeled *C atoms readily takes place via a retro-metathesis process followed by a cyclization of the resulting vinylidene ligand giving the cyclic carbene complex 5, which is fully characterized by single-crystal X-ray diffraction analysis. The protonation of 2a in MeOH is followed by a cyclization, also giving 5. Deuterium-labeling study indicates that the C-C bond formation of this cyclization proceeds simultaneously with the formation of 4 consistent with facile cleavage and reconstruction of C=C bonds. For comparison, complex 4 in alcohol yields, besides 5, the corresponding alkoxycyclohexene 6. Formation of 6 from 4 also involves a skeletal rearrangement with reconstruction of the C=C bond. Interestingly, [[Ru′]=*C=C(Me)-CH ₂CPh₂*CH=CH₂][BF₄] (8′) originally from a complex with two connected labeled carbon atoms also undergoes reestablishment of the *C=*C bond yielding the cyclic allenyl complex 9′. ¹³C-labeling studies clearly reveal the reestablishment of two C=C double bonds in the transformation of both 4 to 5 and 8′ to 9′. The proposed mechanism implicates a cyclobutylidene intermediate formed either via a regiospecific [2+2] cycloaddition of two double bonds in the ruthenium vinylidene 4 or via a cyclization of 4 giving a nonclassical ion intermediate followed by a 1,2-alkyl shift.

Full text of DOI:10.1021/ja074951p

Published on Web 11/10/2007
Intramolecular Cyclization of Ruthenium Vinylidene
Complexes with a Tethering Vinyl Group: Facile Cleavage
and Reconstruction of the C-C Double Bond
Cheng-Wei Cheng, Yi-Chun Kuo, Shu-Hao Chang, Ying-Chih Lin,*
Yi-Hong Liu, and Yu Wang
Contribution from the Department of Chemistry, National Taiwan UniVersity, Taipei,
Taiwan 106, Republic of China
Received July 5, 2007; E-mail: yclin@ntu.edu.tw
Abstract: Protonation of ruthenium acetylide complexes [M]-*Ct*CCPh2CH2CHdCH2 (2a, [M] ) (η5-
C5H5)(P(OPh)3)(PPh3)Ru; 2a′, [M] ) (η5-C5H5)(dppp)Ru; *C ) 13C-labeled carbon atom) with HBF4 in ether
produces [[M]d*CdCHCH2CPh2*CHdCH2][BF4] (4, 4′) exclusively via a metathesis process of the terminal
vinyl group with the *Cd*C of the resulting vinylidene group. For 4 in methanol, bond reconstruction of the
two labeled *C atoms readily takes place via a retro-metathesis process followed by a cyclization of the
resulting vinylidene ligand giving the cyclic carbene complex 5, which is fully characterized by single-
crystal X-ray diffraction analysis. The protonation of 2a in MeOH is followed by a cyclization, also giving 5.
Deuterium-labeling study indicates that the C-C bond formation of this cyclization proceeds simultaneously
with the formation of 4 consistent with facile cleavage and reconstruction of CdC bonds. For comparison,
complex 4 in alcohol yields, besides 5, the corresponding alkoxycyclohexene 6. Formation of 6 from 4 also
involves a skeletal rearrangement with reconstruction of the CdC bond. Interestingly, [[Ru′]d*CdC(Me)-
CH2CPh2*CHdCH2][BF4] (8′) originally from a complex with two connected labeled carbon atoms also
undergoes reestablishment of the *Cd*C bond yielding the cyclic allenyl complex 9′. 13C-labeling studies
clearly reveal the reestablishment of two CdC double bonds in the transformation of both 4 to 5 and 8′ to
9′. The proposed mechanism implicates a cyclobutylidene intermediate formed either via a regiospecific
[2+2] cycloaddition of two double bonds in the ruthenium vinylidene 4 or via a cyclization of 4 giving a
nonclassical ion intermediate followed by a 1,2-alkyl shift.
Introduction
catalyzed cycloisomerizations of 1,5-enynes have been much
less investigated; however, the known reactivities of 1,5-enynes
Reactions of enynes catalyzed by electrophilic late-transition-
metal complexes have attracted much attention because a variety
of products can be obtained from fairly simple substrates under
mild conditions.1 As a result of the compatibility and the
utilization of very diverse precursors, the metal-catalyzed
cycloisomerization of enyne systems has recently expanded on
synthetically versatile developments, including notably applica-
tions in the total synthesis of natural products.2 Metal-catalyzed
cycloisomerization of enynes often leads to various skeletal
rearrangements because “nonclassical” cations may participate
as reaction intermediates.3 For example, transition-metal-
catalyzed cycloisomerization of 1,6-enynes represents an ef-
ficient strategy for a variety of five-membered and six-
membered alkenes and dienes.4 The corresponding metal-
also involve the same type of cycloisomerization.5 On the other
hand, this very same diversity can be viewed as a disadvantage
from the synthetic viewpoint that the outcome of a specific
transformation may be difficult to predict. Therefore, further
insight into the mechanism of these transformations is desirable.6
Herein, we describe the development of ruthenium-mediated
isomerizations of 1,5-enynes to furnish the other type of 1,5-
enynes and cycloisomerizations to produce alkoxycyclohexenes.
This process was supported by our recent discovery of the
ruthenium-mediated skeletal rearrangement of 3,3-diphenyl-5-
(3) (a) Aubert, C.; Buisine, O.; Malacria, M. Chem. ReV. 2002, 102, 813. (b)
Trost, B. M.; Krische, M. J. Synlett 1998, 1. (c) Ojima, I.; Tzamarioudaki,
M.; Li, Z.; Donovan, R. J. Chem. ReV. 1996, 96, 635. (d) Oi, S.; Tsukamoto,
I.; Miyano, S.; Inoue, Y. Organometallics 2001, 20, 3704.
(4) (a) Driver, S. T.; Geissert, A. J. Chem. ReV. 2004, 104, 1317. (b) Nevado,
C.; Ca´rdenas, D. J.; Echavarren, A. M. Chem.-Eur. J. 2003, 9, 2627.
(5) (a) Mamane, V.; Gress, T.; Krause, H.; Fu¨rstner, A. J. Am. Chem. Soc.
2004, 126, 8654. (b) Harrak, Y.; Blaszykowski, C.; Bernard, M.; Cariou,
K.; Mainetti, E.; Mouries, V.; Dhimane, A. L.; Fensterbank, L.; Malacria,
M. J. Am. Chem. Soc. 2004, 126, 8656. (c) Nieto-Oberhuber, C.; Mun˜oz,
M. P.; Bun˜uel, E.; Nevado, C.; Ca´rdenas, D. J.; Echavarren, A. M. Angew.
Chem., Int. Ed. 2004, 43, 2402.
(6) (a) Me´ndez, M.; Mamane, V.; Fu¨rstner, A. Chemtracts: Org. Chem. 2003,
16, 397. (b) Lloyd-Jones, G. C. Org. Biomol. Chem. 2003, 1, 215. (c) Nieto-
Oberhuber, C.; Lo´pez, S.; Jime´nez-Nu´n˜ez, E.; Echavarren, A. M. Chem.-
Eur. J. 2006, 12, 5916. (d) Echavarren, A. M.; Nevadoa, C. Chem. Soc.
ReV. 2004, 33, 431.
(1) (a) Chatani, N.; Kataoka, K.; Murai, S.; Furukawa, N.; Seki, Y. J. Am.
Chem. Soc. 1998, 120, 9104. (b) Trost, B. M.; Doherty, G. A. J. Am. Chem.
Soc. 2000, 122, 3801. (c) Me´ndez, M.; Mun˜oz, M. P.; Nevado, C.; Ca´rdenas,
D. J.; Echavarren, A. M. J. Am. Chem. Soc. 2001, 123, 10511. (d) Mart´ın-
Matute, B.; Nevado, C.; Ca´rdenas, D. J.; Echavarren, A. M. J. Am. Chem.
Soc. 2003, 125, 5757. (e) Ma, S.; Yu, S.; Gu, Z. Angew. Chem., Int. Ed.
2006, 45, 200. (f) Zhang, L.; Sun, J.; Kozmin, S. A. AdV. Synth. Catal.
2006, 348, 2271.
(2) (a) Fu¨rstner, A.; Stelzer, F.; Szillat, H. J. Am. Chem. Soc. 2001, 123, 11863.
(b) Fu¨rstner, A.; Szillat, H.; Gabor, B.; Mynott, R. J. Am. Chem. Soc. 1998,
120, 8305. (c) Charruault, L.; Michelet, V.; Taras, R.; Gladiali, S.; Geneˆt,
J. P. Chem. Commun. 2004, 850.
9
14974
J. AM. CHEM. SOC. 2007, 129, 14974-14980
10.1021/ja074951p CCC: $37.00 © 2007 American Chemical Society

Cyclization of Ruthenium Vinylidene Complexes
A R T I C L E S
Scheme 1
Figure 1. An ORTEP drawing of 5. Phenyl groups except the C(ipso)
atoms on the phosphorus ligands have been omitted for clarity. Selected
bond distances (Å) and angles (deg): Ru(1)-C(1), 1.957(4); Ru(1)-P(1),
2.2349(10); Ru(1)-P(2), 2.3539(10); C(1)-C(2), 1.441(5); C(2)-C(3),
1.334(5); C(3)-C(4), 1.486(5); C(4)-C(5), 1.532(5); C(5)-C(6), 1.550-
(5); C(1)-C(6), 1.531(5); C(2)-C(1)-C(6), 113.2(3); C(1)-C(2)-C(3),
124.3(3); C(2)-C(3)-C(4), 123.5(4); C(1)-C(6)-C(5), 116.9(3).
electronic as well as the steric effects of the ruthenium fragment.
A series of 2D NMR studies, including COSY, HMQC, and
HMBC experiments, unambiguously establish the structure of
4. Formation of 4′ from 3a′, formally a migration of two phenyl
substituents, could be interpreted by a metathesis process of
two CdC bonds (Scheme 1) involving a double cleavage of
two unsaturated carbon-carbon bonds.7 Formation of 4 from
2a presumably proceeds via a similar pathway.
en-1-yne, which was proposed to proceed via an unusual
mechanism involving a new metathesis process of the terminal
vinyl group with the CdC of the vinylidene group.7 Elucidation
of this novel reaction mechanism enabled us to extend the scope
of the ruthenium fragment.
Reconstruction of Two CdC Bonds. Unexpectedly, treat-
ment of 4 with MeOH affords the carbene complex 5 with an
unsaturated six-membered ring ligand as a reddish orange solid
almost quantitatively (Scheme 1). Complex 5 is characterized
Results and Discussion
Cleavage of Two CdC Bonds. Metathesis of two CdC
double bonds in a vinylidene complex of Cp(PPh3)2Ru (Cp )
η5-C5H5) system containing a tethering vinyl group was recently
reported by us.7 The same metathesis is also observed in similar
vinylidene complexes of Cp(P(OPh)3)(PPh3)Ru and Cp(dppp)-
Ru described below. The reaction of [Ru]Cl ([Ru] ) Cp-
(P(OPh)3)(PPh3)Ru) with HCtCC(Ph)2OH in dichloromethane
at room temperature gives the ruby red allenylidene complex
[[Ru]dCdCdC(Ph)2][PF6]8 (1) in high yield. Similarly, the
allenylidene complex [[Ru′]dCdCdC(Ph)2][PF6] (1′, [Ru′] )
Cp(dppp)Ru) is also obtained in high yield. Regioselective
nucleophilic addition is commonly observed at Cγ of the
allenylidene ligand,9 and by means of this reaction we synthesize
neutral σ-alkynyl complexes [M]-CtCC(Ph)2CH2CHdCH2
(2a, [M] ) [Ru] and 2a′, [M] ) [Ru′]) from the reactions of
Grignard reagent CH2dCHCH2MgCl with 1 and 1′, respectively.
Treatment of the σ-alkynyl complex 2a′ with HBF4 in diethyl
ether at -20 °C generates in high yield the vinylidene complex
[[Ru′]dCdCHC(Ph)2CH2CHdCH2][BF4] (3a′), which in dichlo-
romethane transforms to the other vinylidene complex [[Ru′]d
CdCHCH2C(Ph)2CHdCH2][BF4] (4′) at room temperature.
However, protonation of 2a yields the vinylidene complex 4
directly, and the anticipated vinylidene complex [[Ru]dCd
CHC(Ph)2CH2CHdCH2][BF4] (3a) is too reactive to be isolated
(Scheme 1). The much faster rate of the formation of 4 as
compared to that of the dppp analogue 4′ is ascribed to the
1
by H, 31P{1H}, 13C{1H} NMR, and 2D NMR spectroscopies
and analytical data. In the 13C{1H} NMR spectrum of 5, the
resonance corresponding to the RudCR carbon atom appears
at δ 321.4 as a multiplet. In addition, two singlet resonances at
δ 151.2 and 135.5 are assigned to the olefinic carbon atoms of
1
the six-membered ring on the basis of the H,13C-HMQC and
1H,13C-HMBC spectra. Complex 5 is also directly obtained via
protonation of 2a with HBF4 in MeOH at 0 °C. From a
mechanistic point of view, it should be noted that direct
intramolecular cyclization of the vinylidene with the terminal
vinyl group in 4 should have a preference to give the unsaturated
cyclic carbene complex A (Scheme 1), which is not observed.
Treatment of complex 4′ with MeOH also affords analogous
carbene complex with much lower yield. No attempt was made
to isolate the pure product for 4′.
Slow diffusion of diethyl ether into a solution of 5 in
dichloromethane allows collection of suitable single crystals for
X-ray diffraction study. An ORTEP diagram is shown in Figure
1, and selected structure parameters are listed. The bond length
of Ru(1)-C(1) is 1.957(4) Å showing a typical RudC double
bond, and the C(2)-C(3) bond length is 1.334(5) Å showing a
CdC double bond character. The bond length of C(1)-C(2)
(1.441(5) Å) is shorter than 1.531(5) Å of C(1)-C(6), indicating
delocalization of double bond character at Ru(1)-C(1)-C(2)-
C(3).
(7) Yen, Y. S.; Huang, S. L.; Liu, Y. H.; Sung, H. L.; Wang, Y.; Lin, Y. C.
J. Am. Chem. Soc. 2005, 127, 18037.
(8) Selegue, J. P. Organometallics 1982, 1, 217.
(9) (a) Esteruelas, M. A.; Go´mez, A.; Lo´pez, A. M.; Modrego, J.; On˜ate, E.
Organometallics 1997, 16, 5826. (b) Cadierno, V.; Gamasa, M. P.; Gimeno,
J.; Gonza´lez-Cueva, M.; Lastra, E.; Borge, J.; Garc´ıa-Granda, S.; Pe´rez-
Carreno˜, E. Organometallics 1996, 15, 2137.
The cyclization reaction of 4 in solvent other than MeOH
gives an additional product. Treatment of complex 4 in aqueous
acetone results in the formation of two products identified as 5
9
J. AM. CHEM. SOC. VOL. 129, NO. 48, 2007 14975

A R T I C L E S
Cheng et al.
Figure 2. Resonances of enriched 13C in the 13C spectra of 1-13C, 2a-13C, 4-13C, 5-13C, and 6a-13C.
and the organic cyclic alkene 6a in ca. 1:5 ratio (Scheme 1).10
Scheme 2
Structural assignment of 6a is based on 2D NMR studies,
including COSY, HMQC, and HMBC experiments and mass
spectroscopy. In the 1H NMR spectrum, the relatively downfield
doublet resonance at δ 6.02 is assigned to the olefinic proton
near the gem-diphenyl groups. The multiplet resonance corre-
sponding to the proton of OCH appears at δ 3.78, demonstrating
that OCH is directly bonded to two CH2 units. The anticipated
product B shown in Scheme 1 is ruled out by the spectroscopic
data. For the reaction in a mixture of CH2Cl2/MeOH (1:1), the
organic product 6b along with 5 was obtained. A similar
outcome is obtained in the cyclization of 4 in CH2Cl2/EtOH
(1:1), affording a mixture of 5 and 6c in a 3:1 ratio. Subjection
of 4 to CH2Cl2/iPrOH (1:1) also results in formation of 5 and
6d in a 3:1 ratio. For the reaction in CH2Cl2 in the presence of
alcohol, lowering the concentration of alcohols (MeOH, EtOH,
i
and PrOH) results in the formation of 6 as the major product
(ca. 75%). Gold(I)-catalyzed 5-endo hydroxy- or alkoxycycliza-
by the disappearance of a C-C coupling between resonances
of two enriched carbon atoms for 4-13C. As is also shown in
Figure 2, reconstruction of the two labeled carbon atoms is
revealed in the 13C NMR spectrum showing two resonances at
tion of 1,5-enynes provided access to functionalized five-
membered cyclopentenes where hydroxylation or alkoxylation
took place at the external carbon of the ring skeletal.11 In
contrast, Kozmin described an intramolecular formation of either
C-O or C-N bonds in the skeletal framework of the ring in
gold(I)-catalyzed synthesis of heterobicyclic alkenes as a result
of the 6-endo-dig carbocyclizations of 1,5-enynes.12 The forma-
tion of 6 is similar to Kozmin’s result.
13C-Labeling Experiment. To obtain information regarding
the bonding relationship of the rearrangement of 3a to give 4
with subsequent transformation to 5 and 6, double labeled 13C-
compounds are prepared. The 13C double labeling at both CR
and Câ for 2a-13C is readily achieved from alkylation of 1a-
13C. The 13C NMR spectrum of 2a-13C displays two intense
resonances at δ 92.8 and 112.9 with 1JC-C ) 122.3 Hz assigned
to the two enriched CR and Câ carbons, respectively, indicating
direct connectivity (Figure 2). Treatment of 2a-13C with HBF4
exclusively affords 4-13C, in which the two labeled 13C atoms
are at CR (a doublet of doublet resonance at δ 350.2 with 2JC-P
) 21.0 Hz and 2JC-P′ ) 14.0 Hz) and at the internal vinyl CH
unit (a singlet resonance at δ 143.6). Cleavage of two carbon
atoms in the transformation of 2a to 4 is noticeably observed
1
δ 321.1 and 77.2 with JCC ) 23.8 Hz of the product 5-13C
obtained from 4-13C. The formation of alkoxy cyclic alkene 6
presumably also involves the same skeletal rearrangement. The
13C NMR spectrum of 6a-13C obtained from 4-13C in aqueous
1
acetone shows two resonances at δ 134.4 and 125.2 with JCC
) 69.4 Hz, indicating direct bonding of two 13C-enriched
carbons. The formation of product 6 is thus proposed to proceed
via skeletal rearrangement of 4 rather than a simple direct C-C
bond formation.
To further understand the mechanism of the formation of the
unexpected finding of 5, we carry out the protonation of 2a
using the deuterated tetrafluoroboric acid. The addition of excess
amount of DBF4 to a methanol-d4 solution of 2a produces a
1
mixture marked as 5-D, which H NMR displays deuterium
contents of 100% and 50% at the C6 and C3 carbons, respectively
(Scheme 2). The distribution of deuterium atoms in 5-D is
1
supported by the H NMR spectrum, which contains one 50%
intensity of proton signal at δ 6.34, and the results support the
presence of skeletal rearrangement. Scheme 2 shows a plausible
mechanism to account for the formation of 5-D. Deuteration of
2a generates 3a-d1, which could form either the cyclization
product 5-d2 via pathway a or the metathesis product 4-d1 via
(10) Nieto-Oberhuber, C.; Mun˜oz, M. P.; Lo´pez, S.; Jime´nez-Nu´n˜ez, E.; Nevado,
C.; Herrero-Go´mez, E.; Raducan, M.; Echavarren, A. M. Chem.-Eur. J.
2006, 12, 1677.
(11) Buzas, A. K.; Istrate, F. M.; Gagosz, F. Angew. Chem., Int. Ed. 2007, 46,
1141.
(12) Zhang, L.; Kozmin, S. A. J. Am. Chem. Soc. 2005, 127, 6962.
9
14976 J. AM. CHEM. SOC. VOL. 129, NO. 48, 2007

Cyclization of Ruthenium Vinylidene Complexes
A R T I C L E S
Scheme 3
Scheme 4
pathway is a C-C bond formation followed by 1,2-metal
migration to give C with two separated labeled atoms as shown
in the lower part of Scheme 3. According to the 13C-labeling
results, we proposed that product 5 is derived from 4 via a
skeletal rearrangement. Transformation of 4 to 5 could be
interpreted by a reversed process of formation of 4 giving back
3a via the metathesis route followed by an intramolecular attack
of the terminal olefin to CR generating the cation II (Scheme
3) containing a six-membered ring. Deprotonation at C6 (see
Scheme 3) followed by protonation at C2 leads to the product
5. Scheme 3 also shows an alternative pathway sequentially via
V, IV, I, then the cation III, which also undergoes deprotonation
and protonation to give the observed product 5.
Formation of the alkoxy-cyclic alkene products 6 can be
rationalized using the mechanistic analysis presented also in
Scheme 3. The transformation of complex 4 to the cationic
species II is followed by a nucleophilic attack of an alkoxy
group with subsequent cleavage of the ruthenium-cyclic alkene
bond producing compound 6 and ruthenium species, which is
not identified.
A Further Example. Two neutral σ-alkynyl complexes
[M]-CtCC(Ph)2CH2C(Me)dCH2 (2b, [M] ) [Ru] and 2b′,
[M] ) [Ru′]) are synthesized from the reactions of the Grignard
reagent CH2dC(Me)CH2MgCl with 1 and 1′, respectively.9 With
only an additional methyl group on the internal carbon of the
terminal vinyl functionality, complex 2b′, upon protonation, is
converted to complex 9′ containing a cyclic π-allenyl ligand
(Scheme 4).7,16 A mixture of diastereomers of 9 is also obtained
directly and instantaneously from protonation of 2b. In such a
cyclization, no C-C bond cleavage was observed. We are
surprised to observe the completely different reactivity between
the allyl- and 2-methylallyl-substituted vinylidene complexes.
It is therefore interesting to explore the chemical reactivity of
similar metal vinylidene complex containing a methyl group,
instead of a hydrogen, at Câ, that is, [[Ru′]dCdC(Me)-
CH2C(Ph)2CHdCH2][BF4]. For this reason, the following
experiments shown in Scheme 4 are carried out. Deprotonation
of 4′ generates the acetylide complex 7′. Methylation of 7′ using
methyl triflate takes place at Câ, giving the unstable vinylidene
complex 8′, which undergoes a cyclization to also generate 9′.
pathway b. Fast exchange of the vinylidene proton of 4-d1 as
shown in pathway c followed by retro-metathesis and cyclization
results in 5-d3 as the final product. Thus, the deuteration of 2a
should yield 5-D: a mixture of 5-d2 and 5-d3. Presumably, the
rate of proton exchange (pathway c) between the vinylidene
proton and CD3OD should be much faster than the rate of the
metathesis reaction (pathway b) and the cyclization (pathway
a), which are probably approximately comparable. This labeling
experiment also indicates that the transformation of 4 to 5
proceeds via the reversed metathesis reaction pathway to 3a
first. Therefore, subjection of 4 in CD3OD should give 5-d3
with complete D-labeling at C6 and C3 carbons (Scheme 2). As
shown in Scheme 3, for the formation of 4′, the double cleavage
may proceed either via a [2+2] cycloaddition of the two double
bond in 3a′ leading to an unobserved species I followed by a
retro-cycloaddition to give the observed product13 or via
formation of a bicyclic species III followed by 1,2-methylene
shift.14 Our studies establish that the presence of a ruthenium
vinylidene fragment is responsible for the novel skeletal
reorganization to furnish another type of vinylidene complex
possibly due to efficient stabilization of the cationic intermediate
I. In the absence of the vinylidene fragment, the cyclization by
gold-based catalyst afforded exclusively the [3.1.0] bicyclo-
hexene.15
The formation of 5 shows an interesting ring closure that may
be caused by two different pathways. The upper portion of
Scheme 3 shows the skeletal rearrangement to give 5 with two
labeled carbon atoms bound together. An alternative yet simpler
(13) Sun, J.; Conley, M. P.; Zhang, L.; Kozmin, S. A. J. Am. Chem. Soc. 2006,
128, 9705.
(14) (a) Alvarez, P.; Lastra, E.; Gimeno, J.; Bassetti, M.; Falvello, L. R. J. Am.
Chem. Soc. 2003, 125, 2386. (b) Bran˜a, P.; Gimeno, J.; Sordo, J. A. J.
Org. Chem. 2004, 69, 2544.
(15) Luzung, M. R.; Markham, J. P.; Toste, F. D. J. Am. Chem. Soc. 2004, 126,
10858.
(16) Cadierno, V.; Conejero, S.; D´ıez, J.; Gamasa, M. P.; Gimeno, J.; Garc´ıa-
Granda, S. Chem. Commun. 2003, 840.
9
J. AM. CHEM. SOC. VOL. 129, NO. 48, 2007 14977

A R T I C L E S
Cheng et al.
10b-D with a completely deuterated methylene group at Câ in
the ring is obtained. The presence of two deuterium atoms in
the six-membered ring is consistent with facile protonation of
the vinyl carbon in VI shown in Scheme 5. The anticipated
cyclic organic compound E via a demetallation process was
not observed. However, nucleophilic cyclization of enediynes
catalyzed by [TpRu(PPh3)(CH3CN)2][PF6] resulting in aroma-
tized product similar to E has been reported by Liu.17
Conclusion
In summary, we report that the protonation of 2a in Et2O
affords 4 via an unusual metathesis process of the terminal vinyl
group and the CdC of the vinylidene group of the proposed
intermediate complex 3a. Two CdC bonds are reconstructed
during the transformation of 4 in alcohols to 5 and 6, which
involves a skeletal rearrangement followed by a C-C bond
formation giving cyclic compounds, and the results are supported
by 13C- and 2H-labeling experiments. However, protonation of
the acetylide complex 2b′ with a 2-methylallyl group readily
affords the cyclic allenyl complex 9′. Interestingly, reestablish-
ment of two CdC double bonds could also be observed in the
vinylidene complex with a methyl and the same butenyl group
at Câ, giving also 9′. Metathesis of two CdC bonds takes place
for the transformation of 3a′ to 4′. Deprotonation of 4′ yields
the acetylide complex 7′, which undergoes methylation at Câ
to give the vinylidene product 8′. The retro-metathesis process
of 8′ establishing two original CdC bonds in 3a′ is followed
by a cyclization of the resulting vinylidene ligand also producing
9′. 13C-labeling studies clearly reveal reestablishment of the Cd
C double bond in the transformation of 8′ to 9′. Importantly,
the vinylidene moiety is uniquely responsible for the novel
mechanism of the cycloisomerization, which is proposed to
involve a regiospecific [2+2] cycloaddition of two double bonds
in 4 or 4′, or a cyclization of ruthenium vinylidene 4 or 4′ to
give a nonclassical ion followed by a cascade of 1,2-alkyl shift
to form the cyclobutylidene intermediate I.
Figure 3. Signal of resonances of enriched 13C in the 13C spectra of 7′-
13C, 8′-13C, and 9′-13C.
Scheme 5
The anticipated complex D with two separated labeled carbon
atoms shown in Scheme 4 is not observed.
The 13C-labeling experiment also elucidates the mechanism
of such a ring closure process. Using 25% doubly 13C-enriched
sample, separation of two 13C-labeled atoms in 4′-13C obtained
1
from 3a′-13C is confirmed by the disappearance of the JC-C
(Figure 3). Deprotonation of 4′-13C gives 7′-13C, and then
methylation of 7′-13C at Câ yields the vinylidene complex 8′-
13C. A retro-metathesis process establishing the original C-C
bond of the two enriched 13C atoms is followed by a cyclization
of the resulting vinylidene ligand giving complex 9′-13C. As
mentioned before, the cyclic allenyl complex 9′ can also be
readily prepared from the vinylidene complex 2b′. 13C-labeling
studies clearly reveal the reestablishment of the CdC double
bond again in the transformation of 8′ to 9′. The 13C-13C
coupling constant of 81.6 Hz of 9′-13C as shown in Figure 3
Experimental Section
General Procedures. The manipulations were performed under an
atmosphere of dry nitrogen using a vacuum-line and standard Schlenk
techniques. Solvents were dried by standard methods and distilled under
nitrogen before use. All reagents were obtained from commercial
suppliers (TMS13Ct13CH from Isotec) and used without further
purification. The complexes Cp(PPh3)2RuCl,18a Cp(P(OPh)3)(PPh3)-
RuCl,18b and Cp(dppp)RuCl18c were prepared by literature methods.
The C and H analyses were carried out with a Perkin-Elmer 2400
microanalyzer. Mass spectra (FAB) were recorded using a JEOL SX-
102A spectrometer; 3-nitrobenzyl alcohol (NBA) was used as the
matrix. NMR spectra were recorded on a Bruker AC-300 instrument
at 300 MHz (1H), 121.5 MHz (31P), or 75.4 MHz (13C) using SiMe4 or
85% H3PO4 as a standard or an Avance 500 FT-NMR spectrometer.
Synthesis of Ruthenium Vinylidene Complexes 4 and 4′. [[Ru]d
CdCHCH2C(Ph)2CHdCH2][BF4] (4). A solution of HBF4‚Et2O
(0.200 mL, 1.0 M) in diethyl ether was added dropwise at -20 °C to
a stirred solution of 2a (0.100 g, 0.103 mol) in 20 mL of diethyl ether.
Immediately, an insoluble solid formed, but the addition was continued
until no solid was further formed. The solution was decanted, and the
orange solid 4 was washed with diethyl ether (3 × 5 mL) and dried in
1
falls in the range of JC-C coupling.
Cyclization of the Alkynyl Vinylidene Moiety. The vi-
nylidene complex 3c containing a terminal alkynyl group could
also be obtained from alkylation of 1 using HCtCCH2MgBr
followed by protonation. Treatment of 3c with aqueous acetone
gives the cyclic carbene complex 10a in high yield; see Scheme
1
5. The structure of 10a is established by its H, 13C, and 2D
NMR spectra. In the 13C NMR spectrum, the broad resonance
at δ 300.5 is assigned to the carbene carbon. In 10a with two
different phosphorus ligands, the restricted rotation of the Rud
C bond caused by the presence of the gem-diphenyl group
generates diastereoisomers making the CR carbon resonate as
a broad peak. The same synthetic strategy is used to obtain other
cyclic carbene complexes 10b and 10c containing methoxy and
ethoxy functionalities from the reaction of 3c with MeOH and
EtOH, respectively. In the presence of d4-methanol, complex
(17) Odedra, A.; Wu, C. J.; Pratap, T. B.; Huang, C. W.; Ran, Y. F.; Liu, R. S.
J. Am. Chem. Soc. 2005, 127, 3406.
(18) (a) Bruce, M. I.; Wallis, R. C. Aust. J. Chem. 1979, 32, 1471. (b) Joslin,
F. L.; Mague, J. T.; Roundhill, D. M. Organometallics 1991, 10, 521. (c)
Oshima, N.; Suzuki, H.; Moro-Oka, Y. Chem. Lett. 1984, 1161.
9
14978 J. AM. CHEM. SOC. VOL. 129, NO. 48, 2007

Cyclization of Ruthenium Vinylidene Complexes
A R T I C L E S
1
3
2
vacuo. Yield: 0.108 g (95%). H NMR (δ, CDCl3): 7.53-6.69 (m,
) 17.1 Hz, JHH ) 5.2 Hz, 1H, CH2), 2.33 (t, JHH ) 12.1 Hz, 1H,
40H, Ph), 6.28 (dd, 3JHH ) 17.4 Hz, 3JHH ) 10.8 Hz, 1H, -CHdCH2),
CH2), 2.10 (dd, JHH ) 17.1 Hz, JHH ) 9.5 Hz, 1H, CH2). 13C{1H}
NMR (δ, CDCl3): 134.7 (CH2CHdCH), 125.0 (CH2CHdCH), 149.5-
120.8 (Ph), 73.6 (OCH), 55.1 (OMe), 50.7 (C), 42.0 (CH2), 32.3 (CH2).
EI-MS m/z (%, relative intensity): 264 (M+, 12%). Anal. Calcd for
C18H18O: C, 86.36; H, 7.25. Found: C, 86.23; H, 7.15.
2
2
3
3
5.21 (d, JHH ) 10.8, 1H, dCH2), 5.02 (s, 5H, Cp), 4.55 (d, JHH
)
17.4 Hz, 1H, dCH2), 3.78 (m, 1H, dCâH), 2.68 (dd, 2JHH ) 13.9 Hz,
3JHH ) 5.8 Hz, 1H, CγH2), 2.41 (dd, JHH ) 13.9 Hz, JHH ) 5.8 Hz,
2
3
1H, CγH2). 13C{1H} NMR (δ, CD2Cl2): 351.1 (dd, JPC ) 18.6 Hz,
2
2JPC ) 15.1 Hz, CR), 149.5-126.4 (Ph + dCH), 119.2 (Câ), 115.6
(dCH2), 93.4 (Cp), 51.3 (C), 31.0 (CH2). 31P{1H} NMR (δ, CDCl3):
131.7 (d, 2JPP ) 47.3 Hz), 46.5 (d, 2JPP ) 47.3 Hz). MS (FAB+) m/z:
971.3 (M+), 739.3 (CpRuPPh3P(OPh)3). Anal. Calcd for C59H51BF4O3P2-
Ru: C, 66.99; H, 4.86. Found: C, 67.11; H, 4.77.
5-Ethoxy-3,3-diphenylcyclohex-1-ene (6c). Yield: 0.019 g (73%).
1H NMR (δ, CDCl3): 7.31-7.19 (m, 10H, Ph), 6.09 (d, JHH ) 8.4
2
Hz, 1H, CH2CHdCH), 5.88 (m, 1H, CH2CHdCH), 3.50 (m, 1H, OCH),
3.45 (q, 2JHH ) 7.0 Hz, OCH2CH3), 2.72 (d, 2JHH ) 12.3 Hz, 1H, CH2),
2.52 (m, 1H, CH2), 2.21 (m, 1H, CH2), 2.12 (m, 1H, CH2), 1.16 (t,
2JHH ) 7.0 Hz, CH2CH3). 13C{1H} NMR (δ, CDCl3): 134.5 (CH2CHd
CH), 125.2 (CH2CHdCH), 149.5-120.4 (Ph), 70.3 (OCH), 65.1
(OCH2), 50.5 (C), 42.4 (CH2), 32.2 (CH2), 15.4 (CH3). EI-MS m/z (%,
relative intensity): 278 (M+, 14%). Anal. Calcd for C20H22O: C, 86.29;
H, 7.97. Found: C, 86.34; H, 7.86.
[[Ru′]dCdCHCH2C(Ph)2CHdCH2][BF4] (4′). A Schlenk flask
was charged with 3a′ (0.10 g, 0.11 mmol) and CH2Cl2 (15 mL), and
the mixture was stirred for 2 h. The solvent was reduced to 5 mL under
vacuum, and then the residue mixture was added to 30 mL of diethyl
ether. The chestnut brown precipitate thus formed was filtered and
washed with diethyl ether (2 × 5 mL) and dried under vacuum to give
4′ (0.09 g, yield 90%). 1H NMR (δ, CDCl3): 7.42-7.05 (m, 30H, Ph),
5-Isopropoxy-3,3-diphenylcyclohex-1-ene (6d). Yield: 0.020 g
(75%). H NMR (δ, CDCl3): 7.32-6.98 (m, 10H, Ph), 6.11 (d, JHH
) 9.4 Hz, 1H, CH2CHdCH), 5.88 (m, 1H, CH2CHdCH), 3.65 (m,
1
2
3
3
3
6.33 (dd, JHH ) 17.5 Hz, JHH ) 10.8 Hz, 2H, dCH2), 5.20 (d, JHH
) 10.8 Hz, 1H, dCH2), 5.18 (s, 5H, Cp), 4.77 (d, 3JHH ) 17.5 Hz, 1H,
2
1H, OCH(Me)2), 3.52 (m, 1H, OCH), 2.69 (d, JHH ) 12.3 Hz, 1H,
3
3
CH2), 2.42 (dt, 2JHH ) 17.3 Hz, 3JHH ) 5.2 Hz, 1H, CH), 2.16 (m, 1H,
dCH2), 4.21 (t, JHH ) 7.8 Hz, 1H, dCâH), 3.13 (d, JHH ) 7.8 Hz,
2H, CH2), 2.67-1.75 (m, 6H, dppp). 13C{1H} NMR (δ, CD2Cl2): 343.2
(t, JPC ) 16.0 Hz, CR), 145.5-126.5 (m, Ph), 143.4 (s, -CHdCH2),
2
2
CH2), 2.05 (dd, JHH ) 17.3 Hz, JHH ) 9.5 Hz, 1H, CH2), 1.05 (m,
6H, 2CH3). 13C{1H} NMR (δ, CDCl3): 134.2 (CH2CHdCH), 125.4
(CH2CHdCH), 149.5-120.2 (Ph), 69.1 (OCH), 68.1 (OCH(CH3)2),
50.5 (C), 42.8 (CH2), 32.2 (CH2), 22.4 (CH3), 22.2 (CH3). EI-MS m/z
(%, relative intensity): 292 (M+, 5%). Anal. Calcd for C21H24O: C,
86.26; H, 8.27. Found: C, 86.33; H, 8.19.
2
114.8 (s, dCH2), 108.0 (s, Câ), 92.6 (s, Cp), 53.7 (s, Cγ), 29.7 (s, CH2),
26.7-20.3 (m, dppp). 31P{1H} NMR (δ, CDCl3): 36.6. Anal. Calcd
for C50H47BF4P2Ru: C, 66.89; H, 5.28. Found: C, 66.74; H, 5.37.
Synthesis of Cyclic Carbene Complex 5. Method 1: A solution
of HBF4‚Et2O in diethyl ether was added dropwise to a solution of 2a
(0.100 g, 0.103 mol) in methanol (20 mL) at 0 °C. The resulting solution
was further stirred for 1 h at room temperature and then dried under
vacuum. The resulting powder was washed with diethyl ether (3 × 5
mL) and was identified as 5 (0.104 g, 92%). Method 2: A solution of
complex 4 (0.100 g, 0.095 mmol) in MeOH was stirred for 1 h at room
temperature under nitrogen. The resulting solution was dried under
vacuum to give complex 5 quantitatively. 1H NMR (δ, CDCl3): 7.36-
6.68 (m, 41H, Ph and dCâH), 6.31 (br, 1H, dCγH), 5.12 (s, 5H, Cp),
Preparation of [Ru′]-CtCCH2C(Ph)2CHdCH2 (7′). Complex 4′
(0.300 g, 0.334 mmol) was treated with excess sodium methoxide (0.020
g, 0.370 mmol) in methanol (10 mL), and the light-yellow precipitate
formed immediately. Stirring was continued until no further solid was
formed. The precipitate was filtered, washed with methanol (2 × 5
mL), and dried under vacuum to give complex 7′ (0.242 g, yield 89%).
1H NMR (δ, CDCl3): 7.88-7.00 (m, 30H, Ph), 5.22 (d, JHH ) 17.5
Hz, 1H, dCH2), 5.13 (d, JHH ) 10.7 Hz, 1H, dCH2), 4.67 (s, 5H,
2
2
Cp), 3.81 (s, 2H, CH2), 1.99-2.70 (m, 6H, dppp). 13C{1H} NMR (δ,
CD2Cl2): 147.3-125.6 (m, Ph), 147.1 (s, dCH), 114.8 (s, dCH2), 104.3
(s, Câ), 97.9 (t, 2JPC ) 24.5 Hz, CR), 83.7 (s, Cp), 55.7 (s, CPh2), 35.5
(s, CH2), 26.4-21.5 (m, dppp). 31P{1H} NMR (δ, CDCl3): 46.9. Anal.
Calcd for C50H46P2Ru: C, 74.15; H, 5.72. Found: C, 74.32; H, 5.88.
Preparation of [[Ru′]dCdC(Me)CH2C(Ph)2CHdCH2][BF4] (8′).
A flask was charged with 7′ (0.810 g, 1.00 mmol) in dichloromethane
(50 mL) under nitrogen. MeOTf (0.15 mL, 1.1 mmol) was added
dropwise at room temperature, and the color of the solution changed
from yellow to orange immediately. After the mixture was stirred about
10 min, the volume of the solvent was reduced to 5 mL under vacuum,
and then the residue mixture was added to 30 mL of diethyl ether. The
precipitate thus formed was filtered, washed with diethyl ether (2 × 5
mL), and dried under vacuum to give the final product 8′ as a chestnut
brown powder (0.870 g, yield 89%). 1H NMR (δ, CDCl3): 7.39-6.70
(m, 30H, Ph), 6.54 (dd, 3JHH ) 17.5 Hz, 3JHH ) 10.7 Hz, 1H, dCH2),
2
2
4.76 (d, JHH ) 18.1 Hz, 1H, CRCH2), 2.73 (d, JHH ) 20.0 Hz, 1H,
CδH2), 2.68 (d, 2JHH ) 18.1 Hz, 1H, CRCH2), 1.75 (d, 2JHH ) 20.0 Hz,
4JHH ) 5.5 Hz, 1H, CδH2). 13C{1H} NMR (δ, CDCl3): 321.4 (br, CR),
151.2 (Câ), 151.1-120.1 (Ph), 135.5 (Cγ), 94.7 (Cp), 70.6 (CRCH2),
47.5 (C), 39.2 (Cδ). 31P{1H} NMR (δ, CDCl3): 135.2 (d, JPP ) 54.2
2
Hz, P(OPh)3), 51.2 (d, 2JPP ) 54.2 Hz, PPh3). MS (FAB+) m/z: 971.3
(M+), 739.3 (CpRuPPh3P(OPh)3). Anal. Calcd for C59H51BF4O3P2Ru:
C, 66.99; H, 4.86. Found: C, 66.83; H, 4.85.
General Procedure for the Synthesis of 5-Alkoxy-3,3-diphenyl-
cyclohex-1-ene (6). A solution of 4 (0.100 g, 0.095 mmol) in CH2Cl2
(5 mL) was treated with aqueous acetone (6a) or alcohol (0.2 mL, 6b,
6c, and 6d), and the resulting solution was stirred for 24 h at room
temperature under nitrogen. After evaporation of the solvent, the residue
was identified as the mixture of 5 and alkoxy cyclic alkene 6, which
was extracted twice with 10 mL of hexanes and dried in vacuo to give
the crude 6. The crude compound was purified by flash chromatography
(silica gel, hexanes/EtOAc 20/1) to afford 6.
5.28 (s, 5H, Cp), 5.25 (d, 3JHH ) 10.7 Hz, 1H, dCH2), 4.52 (d, 3JHH
)
17.5 Hz, 1H, dCH2), 2.80 (s, 2H, CH2), 2.87-1.93 (m, 6H, dppp),
5,5-Diphenylcyclohex-3-enol (6a). Yield: 0.019 g (84%). 1H NMR
(δ, CDCl3): 7.31-6.87 (m, 10H, Ph), 6.02 (d, JHH ) 10.0 Hz, 1H,
1.07 (s, 3H, CH3). 13C{1H} NMR (δ, CD2Cl2): 348.2 (t, JCP ) 15.5
2
2
Hz, CR), 147.3-117.8 (Ph), 146.2 (s, dCH), 117.6 (s, dCH2), 115.7
(s, Câ), 93.1 (s, Cp), 54.0 (s, Cγ). 31P{1H} NMR (δ, CDCl3): 35.5.
Anal. Calcd for C50H47BF4P2Ru: C, 64.12; H, 5.07. Found: C, 64.23;
H, 5.21.
Synthesis of π-Cyclic Allene Complex 9. A solution of HBF4‚Et2O
in diethyl ether was added dropwise at -20 °C to a stirred solution of
2b (0.100 g, 0.102 mmol) in 20 mL of diethyl ether. Immediately, an
insoluble solid formed, but the addition was continued until no further
solid was formed. The solution was then decanted, and the brown solid
was washed with diethyl ether (3 × 5 mL) and dried in vacuo to give
9. Yield: 0.100 g (88%). Spectroscopic data for 9, 1H NMR (δ,
CDCl3): 7.80-6.73 (m, 40H, Ph), 6.50 (s, 1H, CH), 5.30 (s, 5H, Cp),
CH2CHdCH), 5.68 (m, 1H, CH2CHdCH), 3.80 (br s, 1H, OH), 3.78
2
(m, 1H, OCH), 2.55 (dd, JHH ) 12.3 Hz, 1H, CH2), 2.30-2.21 (m,
2H, CH2), 1.97 (m, 1H, CH2). 13C{1H} NMR (δ, CDCl3): 134.4 (CH2-
CHdCH), 125.2 (CH2CHdCH), 149.5-120.4 (m, Ph), 64.6 (CHOH),
51.0 (C), 45.5 (CH2), 35.1 (CH2). EI-MS m/z (%, relative intensity):
250 (M+, 27%). Anal. Calcd for C18H18O: C, 86.36; H, 7.25. Found:
C, 86.23; H, 7.15.
5-Methoxy-3,3-diphenylcyclohex-1-ene (6b). Yield: 0.016 g (64%).
1H NMR (δ, CDCl3): 7.36-6.90 (m, 10H, Ph), 6.08 (d, JHH ) 9.2
Hz, 1H, CH2CHdCH), 5.71 (m, 1H, CH2CHdCH), 3.50 (m, 1H, OCH),
3.10 (s, 3H, OCH3), 2.91 (d, 2JHH ) 12.5 Hz, 1H, CH2), 2.40 (dt, 2JHH
2
9
J. AM. CHEM. SOC. VOL. 129, NO. 48, 2007 14979

A R T I C L E S
Cheng et al.
2.75 (d, 2JHH ) 12.9 Hz, 1H, CH2), 2.43 (m, 1H, dCH), 2.18 (br, 1H,
Complex 10c. Yield: 0.093 g (89%). 1H NMR (δ, CDCl3): 7.68-
6.52 (m, 41H, Ph and CâH), 4.94 (s, 5H, Cp), 4.64 (d, 2JHH ) 18.0 Hz,
3
CHCH3), 1.74 (m, 1H, CH2), 1.38 (d, JHH ) 6.1 Hz, 3H, CH3). 13C-
{1H} NMR (δ, CDCl3): 151.5-120.1 (Ph), 90.4 (s, Cp), 58.4 (s, Cγ),
51.3 (s, CH2), 42.5 (s, CH), 35.6 (s, CH), 20.3 (s, CH3). 31P{1H} NMR
1H, CRCH2), 3.73 (q, 2H, 2JHH ) 6.5 Hz, OCH2CH3), 3.48 (d, 2JHH
)
2
18.0 Hz, 1H, CRCH2), 2.77 (d, JHH ) 18.1 Hz, 1H, CδH2), 2.25 (d,
2JHH ) 18.1 Hz, 1H, CδH2), 1.32 (t, 2JHH ) 6.5 Hz, 3H, CH3). 13C{1H}
NMR (δ, CDCl3): 300.7 (br, CR), 168.0 (Cγ), 145.3 (Câ), 151.5-121.7
(m, Ph), 91.8 (Cp), 67.0 (CRCH2), 66.6 (OCH2CH3), 47.6 (C), 42.2
(Cδ), 14.1 (CH3). 31P{1H} NMR (δ, CDCl3): 136.8 (d, 2JPP ) 58.8 Hz,
2
2
(δ, CDCl3): 121.7 (d, JPP ) 60.5 Hz, P(OPh)3), 45.0 (d, JPP ) 60.5
1
Hz, PPh3). Spectroscopic data of the other diastereomer, H NMR (δ,
CDCl3): 7.80-6.73 (m, 40H, Ph), 5.27 (s, 5H, Cp), 4.96 (s, 1H, CH),
2.85 (m, 1H, dCH), 2.71 (d, 2JHH ) 13.0 Hz, 1H, CH2), 2.06 (m, 1H,
3
CH2), 1.68 (br, 1H, CHCH3), 1.37 (d, JHH ) 6.0 Hz, 3H, CH3). 13C-
2
P(OPh)3), 54.8 (d, JPP ) 58.8 Hz, PPh3). MS (FAB+) m/z: 1015.3
{1H} NMR (δ, CDCl3): 151.5-120.1 (Ph), 91.2 (s, Cp), 58.2 (s, Cγ),
50.9 (s, CH2), 42.6 (s, CH), 35.5 (s, CH), 19.8 (s, CH3). 31P{1H} NMR
(M+), 739.3 (CpRuPPh3P(OPh)3). Anal. Calcd for C61H55BF4O4P2Ru:
C, 66.49; H, 5.03. Found: C, 66.55; H, 5.12.
2
2
(δ, CDCl3): 124.7 (d, JPP ) 58.2 Hz, P(OPh)3), 45.4 (d, JPP ) 58.2
Hz, PPh3). MS (FAB+) m/z: 985.3 (M+), 739.3 (CpRuPPh3P(OPh)3).
Anal. Calcd for C60H53BF4O3P2Ru: C, 67.23; H, 4.98. Found: C, 67.29;
H, 4.87.
Single-Crystal X-ray Diffraction Analysis of 5. Single crystals of
5 suitable for an X-ray diffraction study were grown as mentioned
above. A single crystal of dimensions 0.20 × 0.15 × 0.10 mm3 was
glued to a glass fiber and mounted on an SMART CCD diffractometer.
The diffraction data were collected using 3 kW sealed-tube Mo KR
radiation (T ) 295 K). Exposure time was 5 s per frame. SADABS19
(Siemens area detector absorption) absorption correction was applied,
and decay was negligible. Data were processed, and the structure was
solved and refined by the SHELXTL20 program. The structure was
solved using direct methods and confirmed by Patterson methods
refining on intensities of all data to give R1 ) 0.1050 and wR2 )
0.1291 for 11 596 unique observed reflections (I > 2σ(I)). Hydrogen
atoms were placed geometrically using the riding model with thermal
parameters set to 1.2 times that for the atoms to which the hydrogen is
attached and 1.5 times that for the methyl hydrogens.
General Procedure for the Synthesis of Alkoxy Cyclic Carbene
Complexes 10. A solution of complex 3c (0.100 g, 0.095 mmol) in
alcohol or aqueous acetone (20 mL)was stirred for 1 h at room
temperature under a nitrogen atmosphere. The resulting solution was
reduced to about 3 mL, which was slowly added to 50 mL of vigorously
stirred diethyl ether to afford the reddish orange precipitate. The powder
was filtered off and washed with diethyl ether and hexanes, to give
the corresponding alkoxy cyclic carbene complex 10.
Complex 10a. Yield: 0.093 g (91%). 1H NMR (δ, CDCl3): 7.51-
6.67 (m, 41H, Ph and CâH), 5.24 (s, 5H, Cp), 4.82 (d, 2JHH ) 18.2 Hz,
2
2
1H, CRCH2), 3.41 (d, JHH ) 18.2 Hz, 1H, CRCH2), 2.95 (d, JHH
)
17.7 Hz, 1H, CδH2), 2.20 (d, 2JHH ) 17.7 Hz, 1H, CδH2). 13C{1H} NMR
(δ, CDCl3): 300.5 (br, CR), 172.2 (Cγ), 146.6 (Câ), 151.2-120.8 (Ph),
92.2 (Cp), 66.0 (CRCH2), 48.4 (C), 42.7 (Cδ). 31P{1H} NMR (δ,
CDCl3): 136.9 (d, 2JPP ) 59.5 Hz, P(OPh)3), 55.7 (d, 2JPP ) 59.5 Hz,
PPh3). MS (FAB+) m/z: 987.3 (M+), 739.3 (CpRuPPh3P(OPh). Anal.
Calcd for C59H51BF4O4P2Ru: C, 65.99; H, 4.79. Found: C, 65.88; H,
4.75.
Acknowledgment. This research is supported by the National
Science Council and National Center of High-Performance
Computing of Taiwan, the Republic of China.
Supporting Information Available: Complete crystallo-
graphic data for 5 (CIF) and preparations and spectroscopic data
of complexes 1, 1′, 2a, 2a′, 2b, 2b′, 2c, 3a′, 3c, and 9′. This
material is available free of charge via the Internet at
http://pubs.acs.org.
Complex 10b. Yield: 0.096 g (93%). 1H NMR (δ, CDCl3): 7.78-
6.52 (m, 41H, Ph and CâH), 5.05 (s, 5H, Cp), 4.72 (d, 2JHH ) 18.3 Hz,
1H, CRCH2), 3.38 (s, 3H, CH3), 3.36 (d, 2JHH ) 18.3 Hz, 1H, CRCH2),
2
2
2.78 (d, JHH ) 18.0 Hz, 1H, CδH2), 2.12 (d, JHH ) 18.0 Hz, 1H,
CδH2). 13C{1H} NMR (δ, CDCl3): 300.5 (br, CR), 168.4 (Cγ), 145.2
(Câ), 151.5-120.1 (m, Ph), 92.2 (Cp), 67.1 (CRCH2), 57.6 (OCH3),
JA074951P
47.5 (C), 42.0 (Cδ). 31P{1H} NMR (δ, CDCl3): 136.8 (d, JPP ) 58.5
2
Hz, P(OPh)3), 55.3 (d, 2JPP ) 58.5 Hz, PPh3). MS (FAB+) m/z: 1001.3
(M+), 739.3 (CpRuPPh3P(OPh)3). Anal. Calcd for C60H53BF4O4P2Ru:
C, 66.24; H, 4.91. Found: C, 66.27; H, 4.82.
(19) The SADABS program is based on the method of Blessing, see: Blessing,
R. H. Acta Crystallogr., Sect. A 1995, 51, 33.
(20) SHELXTL: Structure Analysis Program, version 5.04; Siemens Industrial
Automation Inc.: Madison, WI, 1995.
9
14980 J. AM. CHEM. SOC. VOL. 129, NO. 48, 2007