Tandem cyclization in ruthenium vinylidene complexes with two ester groups

Article abstract of DOI:10.1021/om200143e

The reaction of [Ru]-Cl ([Ru] = Cp(PPh₃)₂Ru) with o-ethynyl-substituted methyl benzoate, followed by a sequential deprotonation and electrophilic alkylation reactions by further reacting with base and various alkyl haloacetates, respectively, generated several disubstituted ruthenium vinylidene complexes. In the deprotonation reactions of these disubstituted vinylidene complexes containing two ester groups, tandem cyclizations of the ligand is accompanied with a methanol elimination to generate a new organometallic product containing a three-ring indenofuranone ligand, which structure has been confirmed by a single-crystal X-ray diffraction analysis. Facile protonation and methylation are observed in these indenofuranone complexes. Additionally, for the simple furyl complex containing an O-benzyl group, a 1,3-migration of the benzyl group is observed to yield a lactone product and a Claisen rearrangement is also observed in analogous complexes with O-allyl or O-propargyl groups.

Full text of DOI:10.1021/om200143e

ARTICLE
pubs.acs.org/Organometallics
Tandem Cyclization in Ruthenium Vinylidene Complexes with Two
Ester Groups
Wei-Chen Chang, Cheng-Wei Cheng, Hao-Wei Ma, Ying-Chih Lin,* and Yi-Hong Liu
Department of Chemistry, National Taiwan University, Taipei, Taiwan 106, Republic of China
S Supporting Information
b
ABSTRACT: The reaction of [Ru]-Cl ([Ru] = Cp(PPh3)2Ru) with o-ethynyl-substituted
methyl benzoate, followed by a sequential deprotonation and electrophilic alkylation reactions
by further reacting with base and various alkyl haloacetates, respectively, generated several
disubstituted ruthenium vinylidene complexes. In the deprotonation reactions of these
disubstituted vinylidene complexes containing two ester groups, tandem cyclizations of the
ligand is accompanied with a methanol elimination to generate a new organometallic product
containing a three-ring indenofuranone ligand, which structure has been confirmed by a single-
crystal X-ray diffraction analysis. Facile protonation and methylation are observed in these
indenofuranone complexes. Additionally, for the simple furyl complex containing an O-benzyl
group, a 1,3-migration of the benzyl group is observed to yield a lactone product and a Claisen
rearrangement is also observed in analogous complexes with O-allyl or O-propargyl groups.
’ INTRODUCTION
extension of our study, herein we report the synthesis of a series
of disubstituted vinylidene complexes, each containing two ester
groups in proximity from o-ethynyl-substituted methyl benzoate
and various alkyl haloacetates. Deprotonation of this vinylidene
complex was found to induce tandem cyclizations involving two
ester groups, leading to the synthesis of indeno[1,2-b]furanone.
Synthesis of derivatives of various indenofuranones have been
reported.12 The intermediate of the tandem cyclization could
also be clearly observed by 31P NMR studies. In addition, in the
simple ruthenium furyl complex with a ꢀOCH2Ph group, 1,3-
benzyl migration under mild conditions led to the formation of a
lactone complex. In a similar ruthenium furyl complex with an O-
allyl or an O-propargyl group, Claisen rearrangement involving
CꢀC bond formation between Cγ and the unsaturated group
also generated the lactone product.
Tandem reactions are known to rapidly and efficiently assem-
ble complex structures from simple starting materials with
minimal production of waste. This type of reaction has been
steadily developed with the goal to provide synthetic efficiency
and atom economy in modern synthetic research.1 Owing to the
ubiquitous presence of heterocyclic rings in innumerable bioac-
tive natural products,2 the synthesis of polycyclic compounds
containing these heterocyclic rings using tandem techniques is an
extensive area of organic chemistry. Derivatives of the furan ring,
which are well-known to exhibit a broad range of biological
activities including anticancer3 and antioxidative activity,4 have
shown significant pharmacological potential.5 The importance of
these heterocyclic products has thus encouraged the develop-
ment of synthesis of new five-membered oxygen heterocycles
embedded in a polycyclic system. Transition-metal-catalyzed
cyclization of alkynes bearing proximate C, O, N nucleophiles
has proven to be a powerful synthetic route to a wide variety of
carbo- and/or heterocycles.6 In particular, the cyclization of
alkynyl and allenyl ketones under various reaction conditions
for furan synthesis have been pursued.7 Significant progress in
gold and platinum catalysis has led to new synthetic methods as
well as versatile applications in the total synthesis of natural
products.8 Hashmi and co-workers reported gold-catalyzed in-
tramolecular alkyne/furan cyclization.9 Recently, a great deal of
attention has been focused on the synthesis of polycyclic
products containing furan and furan derivatives to be used as a
precursor for natural product synthesis, and highly substituted
esters have been considered as useful starting materials for the
synthesis of such natural products.10 The facile conversion of a
ruthenium vinylidene complex containing an ester group to a
furyl complex had been previously reported by us.11 As an
’ RESULTS AND DISCUSSION
Disubstituted Vinylidene Complexes and Cyclization.
Three vinylidene complexes, 5aꢀc, each containing two ester
groups, were prepared from [Ru]-Cl (1, Cp(PPh3)2Ru), o-
ethynyl-substituted methyl benzoate 2, and various alkyl haloa-
cetates following the procedures described previously, as shown
in Scheme 1.11 Treatment of [Ru]-Cl with 2 in the presence of
KPF6 in CH2Cl2 or MeOH for 1 day afforded the cationic
monosubstituted vinylidene complex 3 in high yield. Subsequent
deprotonation of 3 with base in solution generated the neutral
acetylide complex 4, and the mixture changed from orange to
yellow within 15 min. Then, treatment of 4 with three alkyl
Received: February 15, 2011
Published: April 18, 2011
r
2011 American Chemical Society
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|

Organometallics
ARTICLE
Scheme 1
Scheme 2
Scheme 3
haloacetates XCH2CO2R (R = Me, Et, CH2Ph) as alkylating
reagents afforded the cationic disubstituted vinylidene com-
plexes 5aꢀc, respectively. These alkylation reactions could be
speeded up upon heating the reaction mixture to 40 °C, but at
higher temperature, side reactions leading to unidentifiable
1
products took place. In the H NMR spectrum of 5c, the
relatively downfield singlet peak at δ 5.07 is assigned to CH2
bonded to Cβ and the singlet resonance at δ 3.28 is assigned to
CH2Ph. The vinylidene CR resonance in the 13C NMR spectrum
2
appears as a triplet at δ 345.05 with JCP = 14.5 Hz for 5c.
Complexes 5a,b show similar characteristic NMR data.
Complex 6c could be similarly prepared; however, 6c is also
unstable in solution and is observed only in the 31P NMR
spectrum. Further transformation of 6c will be described below.
Direct deprotonation of 5a,b for longer than 20 min and
complexes 6a,b in solution all lead to formation of complexes 8a,
b, respectively. Excess bases speed up the formation of 8. The two
new complexes 8a,b display a distinctive light orange color.
Crystalline precipitates formed directly from the reaction mix-
ture, and the desired product could be obtained in analytically
pure form by simple filtration. In the methoxy region of the 1H
NMR spectrum of 8a, there is only one singlet peak at δ 3.98
assigned to the OMe group on the furyl ring. In the 13C NMR
spectrum of 8a the characteristic CR resonance appears as a
Deprotonation of 5a by n-Bu4NOH in 10 min in acetone
induced a cyclization reaction and yielded the neutral furyl
complex 6a. In 20 min, the reaction proceeded further to yield
complex 8a. As shown in Scheme 1, for the first 10 min, the
reaction is expected to yield both the cyclopropenyl complex 7
and the furyl complex 6, as reported previously.11 The deprotona-
tion presumably yielded a zwitterionic transition state with two
resonance forms: i.e., keto and enol forms. The formation of
complex 6 from 5 via the cyclopropenyl complex 7 was observed
clearly in the 31P NMR spectra. Using 5b as an example, in the
beginning of the reaction, exclusive formation of complex 7b from
5b was revealed by the presence of two doublet resonances at δ
2
52.70 and 45.80 with JPP = 36.3 Hz. Within 10 min a broad
2
triplet at δ 170.85 with JCP = 20.9 Hz, and the carbonyl peak
resonance appears at δ 181.07.
resonance at δ 49.96 assigned to 6b appeared, and the peaks
attributed to 7b disappeared completely. The absence of a
cyclopropenyl product at this time of the reaction could be
reasonably interpreted in terms of comparatively higher strain
energy of the cyclopropenyl ring relative to the five-membered
furyl ring.11 The structures of complexes 6a,b have beendeter-
Formation of complexes 8a,b is believed to proceed via a
formal methanol elimination reaction accompanied by formation
of one CꢀC bond of two sp2 carbons. As shown in Scheme 2,
deprotonation of complex 5a or 5b first affords the keto form
intermediate A, which is followed by an intramolecular C-acyla-
tion reaction to afford the intermediate B.14 The remaining
hydrogen at Cγ of B, which is also between two carbonyl groups,
is expected to be reasonably acidic and thus easily deprotonated,
in the presence of excess base, resulting in a formal methanol
elimination, giving C. The enol form of C then induced a second
intramolecular cyclization, i.e. via a nucleophilic addition of the
1
mined by NMR spectroscopy. The H NMR spectrum of 6a
consists of one characteristic singlet resonance at δ 4.31 assigned
to the methyl unit of the methyl benzoate group and a singlet peak
at δ 3.97 assigned to the OMe group in the furyl ligand. The
proton resonance atδ 5.32 is assigned to the unique proton on the
furyl ring. Transformation of 5 to 6 is reversible; namely, upon
addition of excess acid, complexes 6a,b were both reprotonated,
converting back to the vinylidene complexes 5a,b, respectively.13
15
enol oxygen to CR to yield 8. Complex 6a in acetone was
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Organometallics
ARTICLE
Table 1. Distribution of Products 8c and 9c from 5c
entry
concn of 5c (M)
amt of base (equiv)
8c (%)
9c (%)
1
2
3
4
4.0 ꢁ 10ꢀ3
4.0 ꢁ 10ꢀ3
4.0 ꢁ 10ꢀ4
4.0 ꢁ 10ꢀ4
2
1.5
1.5
<1
100
83
5
0
17
95
0
100
converted to complex 8a within 30 min by a reversible ring-
opening process followed by a formal methanol elimination
reaction and then the same ring-closing process.
Ruthenium Lactone Complexes. Interestingly, when the
deprotonation reaction of the vinylidene complex 5c, containing
a benzyl acetate and a methyl benzoate group, by n-Bu4NOH was
carried out in acetone, two products were obtained. As men-
tioned before, the reaction yielded the indenofuranone complex
8c, the expected product from tandem cyclization. In addition,
complex 9c with a lactone moiety in the ligand, formed by a 1,3-
benzyl migration, was also acquired (see Scheme 3). In order to
better control the reaction for the formation of these two
products, the concentration of the reactant and the amount of
base used in the reaction were modified. Four reaction conditions
were explored, and the results are given in Table 1.
Figure 1. 31P NMR spectra for the deprotonation reaction of 5c in d-
acetone. The peak at δ 42.33 is due to the added [Ru]-COþ. The
conversion from 7c to 8c and 9c is shown clearly.
An investigation into the effect of concentrations of the
reactants indicated that a relatively higher concentration of 5c
and/or base would favor the formation of complex 8c via the
tandem cyclization pathway. When the deprotonation was
carried out at two different concentrations of 5c in acetone at
4 ꢁ 10ꢀ3 and 4 ꢁ 10ꢀ4 M, both with 1.5 equiv of base, complexes
8c and 9c in ratios of 83:17 and 5:95, respectively (entries 2 and 3),
were obtained. Furthermore, when the base quantities were
increased from 1.5 equiv to 2.0 equiv, complex 8c was obtained
as the only product (entry 1). At a lower base concentration,
complex 9c was obtained exclusively via a 1,3-migration pathway
in good yield (entry 4). Presumably the lower base concentration
hindered the second deprotonation step for the formation of 8c.
These two reaction pathways could be revealed when the
reaction was monitored by 31P NMR spectra at low temperature.
Complex 5c was dissolved in d-acetone along with [Ru]-COþ,
used as an internal standard. Several 31P NMR spectra were
recorded at 253 K in a 2 h period after ca. 1.1 equiv of base was
added, and then the temperature was raised to 298 K to speed up
the reaction. In the beginning of the reaction, exclusive formation
of complex 7c was revealed by the presence of two sharp doublet
resonances at δ 53.98 and 44.58 with 2JPP = 35.7 Hz (Figure 1).
Then, a broad resonance at δ 48.59 assigned possibly to B/C (see
Scheme 2) and two doublet resonances at δ 51.58 and 49.32
2
Figure 2. ORTEP drawing of complex 8c. For clarity, aryl groups of the
triphenylphosphine ligands on Ru, except the ipso carbons and PF6ꢀ, are
omitted (thermal ellipsoids are given at the 50% probability level).
Selected bond distances (Å) and angles (deg): Ru(1)ꢀC(1), 2.042(2);
C(1)ꢀC(2), 1.373(3); C(2)ꢀC(3), 1.467(3); C(1)ꢀO(1), 1.453(3);
C(11)ꢀO(1), 1.340(3); C(9)ꢀO(2), 1.224(3); C(11)ꢀO(3),
1.329(3); Ru(1)ꢀC(1)ꢀC(2), 142.6(2); O(1)ꢀC(1)ꢀC(2),
103.5(2); C(2)ꢀC(10)ꢀC(11), 105.1(2); C(1)ꢀO(1)ꢀC(11),
109.8(2); O(1)ꢀC(11)ꢀO(3), 111.9(2); C(10)ꢀC(11)ꢀO(3),
137.1(2).
with JPP = 38.1 Hz assigned to 6c, with a ratio of 1:2, were
detected. The broad resonance in the 31P NMR spectrum of 6c at
298 K splits at 253 K into a pair of two doublets. The decoalescence
process is believed to be caused by the restricted rotation of the
CꢀC bond between the furyl group and the methyl benzoate group.
Complex 7c was converted to 6c and A, which was then converted
to B/C (see Scheme 2), in a ratio of 1:2. Complex 6c was then
converted to complex 9c, displaying two sharp doublet resonances
at δ 51.80 and 47.85 with 2JPP = 37.3 Hz. A resonance at δ 48.97
attributed to complex 8c was also observed, most likely formed from
the intermediate B/C.11 The ratio of the two final products,
complexes 8c and 9c in a ratio of ca. 1:2, was approximately the
same as the ratio of two intermediates B/C and 6c. Pure complex 9c,
dissolved in d-acetone with excess base for 2 days, did not yield
complex 8c. Therefore, complexes 8c and 9c are not interconver-
tible and the transformation from 6c to 9c is not reversible.
Single crystals of complex 8c were obtained from acetone. The
solid-state structure of 8c was determined by a single crystal
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Organometallics
ARTICLE
Scheme 4
Scheme 5
X-ray diffraction analysis. An ORTEP type view of the neutral
complex is shown in Figure 2. Selected bond distances and angles
are given in the figure caption. Bond formation between C(9)
and C(10) between the furyl group and the carbonyl carbon
atom of the methyl acetate group on the aromatic ring is clearly
revealed, with the bond distance of C(9)ꢀC(10) being 1.459(3)
Å. The C(9)ꢀO(2) distance of 1.224(3) Å shows a CO double
bond. The RuꢀC(1) bond length of 2.042(2) Å indicates a
RuꢀC single bond, and the C(1)ꢀC(2) and C(10)ꢀC(11)
bond lengths of 1.373(3) and 1.357(3) Å, respectively, are both
typical CdC double bonds.
As for 9c, the 1,3-benzyl migration in the furyl ring of 6c,
classified as a sigmatropic process, results in the formation of the
lactone complex. Similar 1,3-benzyl migration has been de-
scribed in the literature.16 Examples of competitive 1,3- and
1,5-migrations have also been noted in the 2-(benzyloxy)-
3-(trifluoromethyl)furan series.17 Complex 9c was obtained at
room temperature, and 1,5-migration was not detected. The
regioselectivity may be attributed to the steric effect of the bulky
ruthenium fragment.
Since the Claisen rearrangement is a well-known process for
an allyl vinyl ether, the same migration is expected to take place in
the analogous vinylidene complex with an allyl group substituting
the benzyl group. However, treatment of the acetylide complex
4 with allyl 2-bromoacetate did not generate the expected
vinylidene complex; instead, the vþinylidene complex [Ru]dCd
C(C6H4COOMe)CH2CHdCH2 from addition of only the
allylic group was obtained as the only product. Allylation directly
took place at Cβ, instead of alkylation of the whole allyl
haloacetate group. Therefore, a few other vinylidene complexes
were synthesized as precursors in order to further explore this
migration process on the furyl ligand. As shown in Scheme 4, the
acetylide complex 10 with a terminal methyl group was used
as a starting material to synthesize the various disubstituted
vinylidene complexes 11aꢀd via alkylation using four different
alkyl haloacetates XCH2CO2R (R = Et, CH2Ph, CH2CtCH,
CH2CMedCH2), respectively, in the presence of KPF6 in
CH2Cl2 at different temperatures. Complexes 11bꢀd havevar-
ious unsaturated organic moieties on the ester group for the
purpose of investigating the migration process.
reaction process, the same as that mentioned for complex 5c.
That is, a cyclization is followed by a migration process, to give
complex 13b in moderate yield. The reaction proceeds via the
unstable furyl intermediate 12b, which could only be character-
ized by 31P and 1H NMR spectra. The 1H NMR spectrum of 12b
consists of two singlet resonances at δ 5.35 and δ 4.34, assigned
1
to CγH and CH2 of the benzyl group, respectively. In the H
NMR spectrum of 13b a multiplet resonance at δ 2.96 is assigned
to CγH and multiplet resonances with an AB pattern at δ 2.82
2
and 2.46 with JHH = 13.7 Hz are assigned to the CH2 of the
benzyl group at Cγ. Two doublet resonances at δ 53.31 and 48.42
with 2JPP = 37.9 Hz in the 31P NMR spectrum are due to the
stereogenic center Cγ in 13b.
Deprotonations of complexes 11c,d, containing O-propargyl
and O-methylallyl groups, respectively, were carried out with
base in acetonitrile for 20 min at room temperature. Intramole-
cular cyclization, presumably yielding the furyl intermediate 12,
was quickly followed by a spontaneous Claisen rearrangement at
room temperature to give the orange lactone complexes 13c,d,
respectively, in moderate yields. Complexes 13c,d were char-
acterized by a series of 2D NMR studies and mass spectroscopy.
Attempts to monitor the reaction by NMR failed to give the
spectroscopic data of the proposed furyl complex 12. For the
1
two H NMR spectra of 11c and 13c, it is clear that the
propargylic resonances at δ 4.68 (CH2) and 2.51 (CH) of 11c
with J = 2.3 Hz are converted to the characteristic allenylic
resonances at δ 4.74 (CH2) and 4.90 (CH) attributed to the
CHdCdCH2 group in 13c with the dCH proton showing
coupling with the unique lactone ring proton at δ 3.53 with J =
8.0 Hz. For the conversion of 11d to 13d, the singlet 1H resonance
of the OCH2 group at δ 4.48 is converted to a complicated
multiplet resonance at δ 1.90, which is also coupled with the
unique ring proton at δ 2.69. Therefore, transformations of
complexes 11c,d to 13c,d were considered to proceed via the
Claisen rearrangement, which normally required drastic reaction
conditions. The rearrangement leading to complexes 13c,d was
observed at room temperature.18 The Claisen rearrangement of a
fluorinated system19 has been reported to take place also at room
temperature, and the presence of a trifluoromethyl group was
considered to result in significant rate enhancement. The re-
arrangement process, occurring at room temperature in the
deprotonation of 11, should be assisted by the metal fragment.
Treatment of complex 11a with excess n-Bu4NOH caused the
typical deprotonation-induced cyclization, generating in good
yield the furyl complex 12a, which is stable, and no rearrange-
ment was observed. However, deprotonation of complex 11b
containing the benzyl acetate group at Cβ caused a two-step
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Organometallics
ARTICLE
Protonation and Methylation. The indenofuranone ligands
of complexes 8aꢀc readily undergo electrophilic addition reac-
tions, generating various stable organometallic benzenoid sys-
tems (Scheme 5). Treatment of complex 8a with HBF4 in diethyl
ether at room temperature afforded the carbene complex 14a
together with its isomer 15a in a ratio of 2:1, as determined by
NMR.20 Protonation takes place at the carbonyl group as well as
the at alkoxy-substituted carbon of the furyl ring.
suppliers and were used without further purification. NMR spectra were
recorded on a Bruker AC-300, Avance-400, or DMX-500 FT-NMR
spectrometer. 1H NMR and 13C NMR spectra were obtained in CDCl3
at ambient temperature, and chemical shifts are expressed in parts per
million (δ, ppm). Proton chemical shifts are referenced to 7.26 ppm -
(CHCl3), and carbon chemical shifts are referenced to 77.0 ppm -
(CDCl3). 31P (121 MHz) NMR spectra were measured relative to
external 85% phosphoric acid. Both 13C and 31P spectra were proton-
decoupled spectra. Mass spectra were recorded using LCQ Advantage
(ESI) and Finnigan TSQ 700 spectrometers (EI). X-ray diffraction
studies were carried out at the Regional Center of Analytical Instrument
at the National Taiwan University. The complex [Ru]-Cl ([Ru] =
The 31P NMR spectrum of complex 14a with a stereogenic
center displays two doublet resonances at δ 41.69 and 39.84
with 2JPP = 26.6 Hz. The singlet resonance at δ 39.97 in the 31
P
NMR spectrum is attributed to complex 15a. Deprotonation of
the mixture of two carbene complexes 14a and 15a by triethy-
lamine regenerated complex 8a. Protonation of complexes 8b,c
similarly yielded 14b/15b and 14c/15c mixtures, respectively,
both in a ratio of 2:1. Because indenofuranones are prone to
conjugate addition of nucleophiles at the R-position of the furyl
ring, treatment of complexes 8a,c with MeI afforded complexes
16a,c, respectively (Scheme 5).21 A series of 2D NMR studies
and mass spectroscopy established the structure of 16a. The
triplet resonance at δ 357.35 with 2JCP = 14.0 Hz in the 13C NMR
spectrum of 16a is assigned to the carbene carbon directly bound
to the ruthenium. This resonance is shifted rather downfield relative
to a regular carbene resonance in other ruthenium carbene com-
Cp(PPh3)2Ru)22 was prepared from RuCl3 xH2O, which was pur-
3
chased from Strem Chemicals, according to the literature methods.
Compound 10 was also synthesized according to the literature
methods.22
Synthesis of 3. A solution of [Ru]-Cl (0.50 g, 0.69 mmol), 2 (0.20 g,
1.24 mmol), and KPF6 (0.25 g, 1.36 mmol) in 10 mL of CH2Cl2 was
stirred for 2 days under nitrogen at room temperature. Then the solution
was filtered through Celite to remove the insoluble precipitates. Subse-
quently, the volume of the solution was reduced to ca. 2 mL under
vacuum and was added to 50 mL of ether to give an orange precipitate,
which was filtered and washed with ether and dried under vacuum to give
complex 3 (0.61 g, 89% yield). Spectroscopic data for 3 are as follows. 1H
NMR (δ, CDCl3): 8.00ꢀ7.01 (m, 34H, Ph); 6.67 (br, CH); 5.28 (s, 5H,
Cp); 3.78 (s, 3H, OMe). 13C NMR (δ, CDCl3): 350.7 (t, 2JCP = 15.7 Hz,
CR); 133.9ꢀ124.8 (Ph); 117.1 (Cβ); 166.1 (CdO); 94.9 (Cp); 52.0
(OMe). 31P NMR (δ, CDCl3): 42.30 (s, 2 PPh3). Anal. Calcd for
C51H43F6O2P3Ru: C, 61.51; H, 4.35. Found: C, 61.23; H, 4.21. MS ESI:
m/z 851.2 (Mþ).
Deprotonation of 3. Complex 3 (0.49 g, 0.50 mmol) was treated
with excess sodium methoxide (0.051 g, 0.93 mmol) in 15 mL of MeOH.
The solution was stirred at room temperature for 20 min under nitrogen.
Subsequently, the solvent was removed and then the residues were
extracted with 4 ꢁ 20 mL of diethyl ether and filtered through Celite.
The solvent of the filtrate was removed under vacuum to give a yellow
precipitate, identified as compound 4 (0.41 g, 96% yield). Spectroscopic
data for 4 are as follows. 1H NMR (δ, C6D6): 8.05ꢀ6.90 (m, 33H, Ph);
4.64 (s, 5H, Cp); 3.69 (s, 3H, OMe). 13C NMR (δ, C6D6): 166.1
(CdO); 95.0 (br, CR); 133.9ꢀ124.8 (Ph); 117.1 (Cβ); 94.9 (Cp); 52.0
(OMe). 31P NMR (δ, C6D6): 52.04 (s, 2 PPh3). Anal. Calcd for
C51H42O2P2Ru: C, 72.07; H, 4.98. Found: C, 72.22; H, 4.88. MS ESI:
m/z 851.16 (Mþ þ 1).
1
plexes. In the H NMR spectrum, two singlet resonances at δ
3.73 and 1.49 are assigned to the methoxyl group and the
methyl group on Cδ, respectively. The 31P NMR spectrum of
complex 16a with a stereogenic center displays two doublet
resonances at δ 39.71 and 39.36 with 2JPP = 27.5 Hz. Complex
16c can be prepared similarly and also shows similar char-
acteristic NMR data.
’ CONCLUSIONS
In conclusion, we have reported reactions of [Ru]Cl with
terminal aromatic alkynes containing o-substituted ester groups
on the phenyl ring, yielding monosubstituted vinylidene pro-
ducts. Deprotonation of these vinylidene complexes followed by
an alkylation using various alkyl haloacetates gave the cationic
disubstituted vinylidene complexes 5 with two ester groups. For
5, cyclization was induced by deprotonation using less than a
stoichiometric amount of base to yield the furyl complexes 6.
Excess bases bring about tandem cyclizations to yield complexes
8 with the indenofuranone ligand, which has been confirmed by a
single-crystal X-ray diffraction analysis. For the deprotonation of
5c with a benzyl acetate group, in addition to 8c, the lactone
complex 9c was obtained by a 1,3-benzyl migration process.
Presumably the migration process takes place at the stage of the
furyl complex 6c obtainable from the first deprotonation of 5c.
Competitive formation of 8c and 9c is controlled by the
concentration of the reactant and the amount of base used in
the reaction. For deprotonation of vinylidene complexes with
analogous ester substituents, Claisen rearrangement of the
methylallyloxy or propargyloxy groups on the furyl ring also
generates lactone complexes at room temperature.
Synthesis of 5a. To a solution of complex 4 (0.31 g, 0.35 mmol)
and KPF6 (0.25 g, 1.36 mmol) in 10 mL of CH2Cl2, was added methyl
2-bromoacetate (0.13 g, 0.85 mmol) at room temperature. The mixture
was stirred for 5 days under nitrogen at 40 °C. The solution was filtered
through Celite to remove insoluble precipitates, and the volume of the
filtrate was reduced to ca. 1 mL under vacuum and was added to an
ether/hexane mixture (1/1, 50 mL) to cause formation of an orange
precipitate, which was filtered and washed with ether and dried under
vacuum to give complex 5a (0.29 g, 77% yield). Spectroscopic data for 5a
are as follows. 1H NMR (δ, CDCl3): 8.07ꢀ6.97 (m, 34H, Ph); 5.23 (s,
5H, Cp); 3.94 (s, 3H, OMe); 3.65 (s, 3H, OMe); 3.28 (s, 2H, CH2). 13
C
2
NMR (δ, CDCl3): 345.4 (t, JCP = 14.5 Hz, CR); 134.1ꢀ128.5 (Ph);
126.6 (Cβ); 172.2 (CdO); 166.3 (CdO); 95.0 (Cp); 52.1 (OMe); 33.9
(CH2). 31P NMR (δ, CDCl3): 42.97 (s, 2 PPh3). Anal. Calcd for
C54H47F6O4P3Ru: C, 60.73; H, 4.44. Found: C, 60.62; H, 4.51. MS ESI:
m/z 923.20 (Mþ).
’ EXPERIMENTAL SECTION
Synthesis of 5b. To a solution of complex 4 (0.33 g, 0.39 mmol) in
10 mL of CH2Cl2, was added 2.5 equiv of ethyl 2-iodoacetate (0.19 g,
0.89 mmol), and the mixture was stirred under nitrogen at room
temperature for 2 days. The solution was filtered through Celite to
remove insoluble precipitates, and the volume of the solution was
General Procedures. The manipulations were performed under
an atmosphere of dry nitrogen using vacuum-line and standard Schlenk
techniques. Solvents were dried by standard methods and were distilled
under nitrogen before use. All reagents were obtained from commercial
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ARTICLE
reduced to ca. 1 mL under vacuum and added to an ether/hexane
mixture (1/1, 50 mL) to give an orange precipitates, which was filtered
and washed with ether and dried under vacuum to give complex 5b (0.30 g,
(Cγ); 85.2 (Cp); 67.0 (OCH2); 51.5 (OMe); 15.0 (CH3). 31P NMR (δ,
C6D6): 50.05 (s, 2 PPh3).
Synthesis of 8c. To a solution of complex 5c (0.33 g, 0.29 mmol) in
3 mL of acetone was added n-Bu4NOH (0.82 mL, 1.0 M in MeOH, 0.82
mmol), and the mixture was stirred under nitrogen for 30 min. The
orange powder that precipitated was collected and washed with acetone
to remove excess base. Then the powder was dried under vacuum to give
8c (0.21 g, 75% yield). Spectroscopic data for 8c are as follows. 1H NMR
(δ, C6D6): 8.11ꢀ6.91 (m, 39H, Ph); 5.73 (s, 2H, CH2); 4.42 (s, 5H,
Cp). 13C NMR (δ, d-acetone): 181.1 (CdO); 174.2 (t, 2JCP = 19.0 Hz,
CR); 161.8 (Cδ); 143.1ꢀ121.8 (Ph and Cβ); 102.8 (Cγ); 85.7 (Cp);
74.4 (CH2). 31P NMR (δ, C6D6): 50.05 (s, 2 PPh3). Anal. Calcd for
C59H46O3P2Ru: C, 73.36; H, 4.80. Found: C, 73.47; H, 4.91. MS ESI:
m/z 967.41 (Mþ þ 1).
1
79% yield). Spectroscopic data for 5b are as follows. H NMR (δ,
CDCl3): 8.04ꢀ6.98 (m, 34H, Ph); 5.26 (s, 5H, Cp); 4.09 (q, 2H, 3JHH
=
=
7.1 Hz, OCH2); 3.94 (s, 3H, OMe); 3.27 (s, 2H, CH2); 1.16 (t, 3H, 3JHH
2
7.1 Hz, CH3). 13C NMR (δ, CDCl3): 345.5 (t, JCP = 14.6 Hz, CR);
134.1ꢀ128.5 (Ph); 126.8 (Cβ); 171.7 (CdO); 166.2 (CdO); 95.0
(Cp); 61.1 (OCH2); 52.2 (OMe); 34.1 (CH2); 14.2 (CH3). 31P NMR
(δ, CDCl3): 42.98 (s, 2 PPh3). Anal. Calcd for C55H49IO4P2Ru: C,
62.09; H, 4.64. Found: C, 58.93; H, 4.08 (deviations may be due to the
presence of both I and I3 anion; no attempt was made to purify the
product) MS ESI: m/z 937.17 (Mþ).
Synthesis of 5c. To a solution of complex 4 (0.31 g, 0.36 mmol)
and KPF6 (0.25 g, 1.36 mmol) in 10 mL of CH2Cl2, was added benzyl
2-bromoacetate (0.21 g, 0.92 mmol), and the solution was stirred under
nitrogen at 40 °C for 7 days. The solution was filtered through Celite to
remove insoluble precipitates, and the volume of the filtrate was reduced
to ca. 1 mL under vacuum and added to anether/hexane mixture (1/1,
50 mL) to give an orange precipitate, which was filtered and washed with
ether and dried under vacuum to give complex 5c (0.35 g, 85% yield).
Spectroscopic data for 5c are as follows. 1H NMR (δ, CDCl3):
8.01ꢀ6.94 (m, 39H, Ph); 5.18 (s, 5H, Cp); 5.08 (s, 2H, OCH2); 3.91
Synthesis of 9c. To a solution of complex 5c (0.24 g, 0.21 mmol) in
3 mL of acetone was added n-Bu4NOH (0.20 mL, 1 M in MeOH, 0.20
mmol), and the mixture was stirred under nitrogen at 40 °C for 2 h. The
mixture was cooled to room temperature, and the solvent was removed
under vacuum. The residues were extracted with hexane to give a light
yellow solution which was then dried under vacuum to give complex 9c
(0.14 g, 69% yield). Spectroscopic data for 9c are as follows. 1H NMR
(C6D6): δ 7.97ꢀ6.94 (m, 39H, Ph); 4.38 (s, 5H, Cp); 4.20 (m, 1H, 3JHH
= 6.2, 7.2 Hz, CH); 3.63 (s, 3H, OMe); 2.84 (dd, 1H, JHH = 14.0, 6.2 Hz,
CH2); 2.59 (dd, 1H, 2JHH = 14.0, 7.2 Hz, CH2). 13C NMR (δ, C6D6):
181.8 (Cδ); 173.2 (t, 2JCP = 14.6 Hz, CR); 168.0 (CdO); 142.1ꢀ125.5
(Ph and Cβ); 84.6 (Cp); 51.5 (OMe); 49.6 (Cγ); 37.1 (CH2). 31P NMR
(δ, C6D6): 53.06, 48.01 (2 d, 2JPP = 37.0 Hz, 2 PPh3). Anal. Calcd for
C60H50O4P2Ru: C, 72.20; H, 5.05. Found: C, 72.36; H, 5.16. MS ESI:
m/z 999.47 (Mþ þ 1).
(s, 3H, OMe); 3.28 (s, 2H, CH2). 13C NMR (δ, CDCl3): 345.1 (t, 2JCP
=
14.5 Hz, CR); 135.3ꢀ128.2 (Ph); 126.7 (Cβ); 171.4 (CdO); 166.1
(CdO); 94.9 (Cp); 66.9 (OCH2); 52.0 (OMe); 34.0 (CH2). 31P NMR
(δ, CDCl3): 42.97 (s, 2 PPh3). Anal. Calcd for C60H51F6O4P3Ru: C,
62.99; H, 4.49. Found: C, 62.89; H, 4.41. MS ESI: m/z 999.11 (Mþ).
Synthesis of 6a and 8a. To a solution of complex 5a (0.36 g, 0.34
mmol) in 3 mL of acetone was added n-Bu4NOH (0.83 mL, 1 M in
MeOH, 0.83 mmol), and the mixture was stirred under nitrogen for 30
min, giving an orange precipitate which was collected by filtration and
washed with cold acetone to remove excess base. The powder was dried
under vacuum to give complex 8a (0.25 g, 85% yield). Spectroscopic
data for 8a are as follows. 1H NMR (δ, C6D6): 8.11ꢀ6.92 (m, 34H, Ph);
4.42 (s, 5H, Cp); 3.98 (s, 3H, OMe). 13C NMR (δ, C6D6): 181.1
(CdO); 170.9 (t, 2JCP = 20.9 Hz, CR); 162.5 (Cδ); 142.8ꢀ121.1 (Ph
and Cβ); 102.8 (Cγ); 85.2 (Cp); 60.3 (OMe). 31P NMR (δ, C6D6):
50.10 (s, 2 PPh3). Anal. Calcd for C53H42O3P2Ru: C, 71.53; H, 4.76.
Found: C, 71.68; H, 4.88. MS ESI: m/z 891.10 (Mþ þ 1). Complex 6a
was observed in NMR spectra for the reaction in C6D6. Spectroscopic
data for 6a are as follows. 1H NMR (δ, C6D6): 8.10ꢀ6.91 (m, 34H, Ph);
5.32 (s, 1H, CH); 4.42 (s, 5H, Cp); 4.31 (s, 3H, OMe); 3.97 (s, 3H,
OMe). 13C NMR (δ, C6D6): 169.4 (CdO); 154.0 (t, 2JCP = 18.90 Hz,
CR); 164.5 (Cδ); 142.9ꢀ121.1 (Ph and Cβ); 87.9 (Cγ); 84.8 (Cp); 58.0
(OMe); 51.5 (OMe). 31P NMR (δ, C6D6): 50.10 (s, 2 PPh3).
Synthesis of 11a. Complex 11a (0.25 g, 95%) was prepared
from [Ru]-CtCMe (0.20 g, 0.27 mmol), KPF6 (0.076 g, 0.41 mmol),
and 5.0 equiv of ICH2CO2Et (0.16 mL, 1.4 mmol) using the same
procedure as that for the synthesis of 5. Spectroscopic data for 11a are
as follows. 1H NMR (δ, CDCl3): 7.40ꢀ6.98 (m, 30H, Ph); 5.24 (s, 5H,
Cp); 4.11 (q, 2H, 3JHH = 6.9 Hz, CH2); 2.78 (s, 2H, CH2); 1.90 (s, 3H,
CH3); 1.16 (t, 3H, 3JHH = 6.9 Hz, CH3). 13C NMR (δ, CDCl3): 350.4
(t, 2JPꢀC = 14.9 Hz, CR); 171.5 (CdO); 135.6ꢀ128.4 (Ph); 117.8 (Cβ);
94.2 (Cp); 61.0 (OCH2); 30.8 (CH2); 14.2 (CH3); 11.3 (CH3). 31P
NMR (δ, CDCl3): 42.72 (s, 2 PPh3). Anal. Calcd for C48H45F6O2-
P3Ru: C, 59.94; H, 4.72. Found: C, 60.11; H, 4.69. MS ESI: m/z
817.18 (Mþ).
Synthesis of 11b. Complex 11b (0.25 g, 88%) was similarly
prepared from [Ru]-CtCMe (0.21 g, 0.28 mmol), KPF6 (0.076 g,
0.410 mmol), and 5.0 equiv of BrCH2CO2CH2Ph (0.31 g, 1.4 mmol).
Spectroscopic data for 11b are as follows. 1H NMR (δ, CDCl3):
7.38ꢀ6.95 (m, 35H, Ph); 5.13 (s, 5H, Cp); 5.12 (s, 2H, OCH2); 2.80
(s, 2H, CH2); 1.90 (s, 3H, CH3). 13C NMR (δ, CDCl3): 350.4 (t, 2JPꢀC
= 15.4 Hz, CR); 171.4 (CdO); 135.8ꢀ128.5 (Ph); 117.9 (Cβ); 94.2
(Cp); 66.9 (OCH2); 30.9 (CH2); 11.2 (CH3). 31P NMR (δ, CDCl3):
42.66 (s, 2 PPh3). IR (KBr, cmꢀ1): ν 1733 (CdO). Anal. Calcd for
C53H47F6O2P3Ru: C, 62.17; H, 4.63. Found: C, 62.23; H, 4.58. MS FAB
m/z: 879.21 (Mþ þ 1), 617.1 (Mþ þ 1 ꢀ PPh3).
Synthesis of 6b and 8b. To a solution of complex 5b (0.39 g, 0.36
mmol) in 3 mL of acetone was added n-Bu4NOH (0.81 mL, 1 M in
MeOH, 0.81 mmol), and the mixture was stirred under nitrogen for 30
min. The orange powder that precipitated was collected and washed
with 2 ꢁ 2 mL of acetone to remove excess base. The powder was dried
under vacuum to give complex 8b (0.29 g, 87% yield). Spectroscopic
data for 8b are as follows. 1H NMR (δ, C6D6): 8.09ꢀ6.92 (m, 34H, Ph);
Synthesis of 11c. Complex 11c (0.23 g, 87%) was similarly
prepared from [Ru]-CtCMe (0.20 g, 0.27 mmol), KPF6 (0.076 g,
0.410 mmol), and 5.0 equiv of BrCH2CO2CH2CtCH (0.24 g, 1.4
mmol). Spectroscopic data for 11c are as follows. 1H NMR (δ, CDCl3):
7.40ꢀ6.98 (m, 30H, Ph); 5.21 (s, 5H, Cp); 4.68 (d, 2H, 4JHH = 2.3 Hz,
OCH2); 2.79 (s, 2H, CH2); 2.51 (t, 1H, 4JHH = 2.3 Hz, CH); 1.92 (s, 3H,
CH3). 13C NMR (δ, CDCl3): 350.4 (t, 2JPꢀC = 14.8 Hz, CR); 170.8 (s,
CdO); 135.5ꢀ127.3 (Ph); 123.0 (Cβ); 95.6 (Cp); 80.1 (tC); 77.2
(tC); 52.4 (OCH2); 30.7 (CH2); 11.4 (CH3). 31P NMR (δ, CDCl3):
42.56 (s, 2 PPh3). Anal. Calcd for C49H43F6O2P3Ru: C, 60.56; H, 4.46.
Found: C, 60.43; H, 4.38. MS FAB m/z: 827.5 (Mþ þ 1), 563.3 (Mþ þ
1 ꢀ PPh3).
4.57 (q, 2H, 3JHH = 7.0 Hz, OCH2); 4.42 (s, 5H, Cp); 0.95 (t, 3H, 3JHH
=
7.0 Hz, CH3). 13C NMR (δ, C6D6): 180.9 (CdO); 170.2 (t, 2JCP = 21.0
Hz, CR); 161.6 (Cδ); 142.7ꢀ121.1 (Ph and Cβ); 102.6 (Cγ); 85.2 (Cp);
69.1 (OCH2); 15.1 (CH3). 31P NMR (δ, C6D6): 50.06 (s, 2 PPh3). Anal.
Calcd for C54H44O3P2Ru: C, 71.75; H, 4.91. Found: C, 71.83; H, 4.81.
MS ESI: m/z 905.14 (Mþ þ 1). Complex 6b was observed by NMR
spectra in C6D6. Spectroscopic data for 6b are as follows. 1H NMR (δ,
C6D6): 8.21ꢀ7.05 (m, 34H, Ph); 5.40 (s, 1H, CH); 4.43 (s, 5H, Cp);
3
4.57 (q, 2H, JHH = 7.0 Hz, OCH2); 4.31 (s, 3H, OMe); 0.83
(t, 3H, 3JHH = 7.0 Hz, CH3). 13C NMR (δ, C6D6): 169.5 (CdO); 154.5
2
(t, JCP = 18.9 Hz, CR); 163.3 (Cδ); 142.9ꢀ121.1 (Ph and Cβ); 89.7
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ARTICLE
Synthesis of 11d. A mixture (0.21 g) of 11d and [[Ru]dCd
C(Me)CH2C(Me)=CH2][PF6] in a ratio of 9:1 was similarly prepared
from [Ru]-CtCMe (0.26 g, 0.33 mmol), KPF6 (0.076 g, 0.41 mmol),
and BrCH2CO2CH2C(Me)dCH2 (0.16 g, 0.82 mmol). No attempt
was made to separate 11d from the mixture. Spectroscopic data for 11d
are as follows. 1H NMR (δ, CDCl3): 7.40ꢀ6.98 (m, 30H, Ph); 5.19 (s,
5H, Cp); 4.93 (br s, 2H, dCH2); 4.48 (s, 2H, OCH2); 2.84 (s, 2H,
CH2); 1.93 (s, 3H, CH3); 1.72 (s, 3H, CH3). 31P NMR (δ, CDCl3):
42.66 (s, PPh3). MS FAB m/z: 844.21 (Mþ þ 1), 581.2 (Mþ þ 1 ꢀ
PPh3).
total weight 0.22 g; estimated weight of 11d 0.20 g, 0.20 mmol) and n-
Bu4NOH (0.25 mL, 1 M in MeOH). Complex 13d (0.15 g, ca. 88%) was
purified by column chromatography from the product mixture. Spectro-
scopic data for 13d are as follows. 1H NMR (δ, C6D6): 7.40ꢀ7.21 (m,
30H, Ph); 4.73 (s, 1H, dCH2); 4.62 (s, 1H, dCH2); 4.27 (s, 5H, Cp);
2.69 (m, 1H, CH); 1.90 (m, 2H, CH2); 1.87 (s, 3H, CH3); 1.69 (s, 3H,
CH3). 13C NMR (δ, C6D6): 182.5 (CdO); 171.3 (t, 2JCP = 19.1 Hz,
CR); 143.6 (dC); 139.8ꢀ127.2 (Ph); 123.5 (Cβ); 112.0 (dCH2); 83.9
(Cp); 46.7 (CγH); 38.9 (CH2); 22.4 (CH3); 14.9 (Me). 31P NMR (δ,
2
C6D6): 51.01, 50.32 (2 d, JPP = 37.2 Hz, PPh3). Anal. Calcd for
C50H46O2P2Ru: C, 71.33; H, 5.51. Found: C, 71.55; H, 5.67. MS FAB:
Synthesis of 12a. To a solution of 11a (0.22 g, 0.23 mmol) in
CH3CN (5 mL) was added a solution of n-Bu4NOH (2.5 mL, 1 M in
MeOH). The mixture was stirred for 20 min at room temperature, and a
light yellow precipitate formed. The precipitate was filtered, washed with
2 ꢁ 5 mL of CH3CN and 2 ꢁ 10 mL of diethyl ether, and dried under
vacuum. The product was identified as 12a (0.15 g, 85%). Spectroscopic
data for 12a are as follows. 1H NMR (δ, C6D6): 7.46ꢀ6.90 (m, 30H,
Ph); 5.33 (s, 1H, CH); 4.47 (s, 5H, Cp); 3.29 (q, 2H, 3JHH = 7.1 Hz,
CH2); 2.26 (s, 3H, CH3); 0.95 (t, 3H, 3JHH = 7.1 Hz, CH3). 13C NMR
(δ, C6D6): 163.2 (Cδ); 149.9 (t, 2JPꢀC = 19.8 Hz, CR); 88.3 (Cβ); 84.4
(Cp); 80.4 (Cγ); 58.6 (OCH2); 15.4 (CH2CH3). 31P NMR (δ, C6D6):
51.53 (s, 2 PPh3). Anal. Calcd for C48H44O2P2Ru: C, 70.66; H, 5.44.
Found: C, 70.83; H, 5.51. MS FAB: m/z 817.20 (Mþ þ 1).
m/z 843.20 (Mþ þ 1).
Reactions of 8aꢀc with HBF4. A typical experimental procedure
for the reaction of HBF4 with 8 is described below. Complex 8a (0.11 g,
0.12 mmol) was treated with excess HBF4 (48% in diethyl ether,
0.04 mL, 0.22 mmol) in diethyl ether (10 mL), and a brown precipitate
formed immediately. The mixture was stirred until no further solid was
formed. The precipitates were collected by filtration and washed with
diethyl ether to yield a mixture of 14a and 15a in a ratio of 2:1 (total
yield: 0.082 g, 82%). No attempt was made to separate the two products.
Spectroscopic data for 14a are as follows. 1H NMR (δ, CDCl3):
7.75ꢀ6.58 (m, 34H, Ph); 5.41 (s, 5H, Cp); 4.27 (s, 1H, CH); 3.76 (s,
3H, OMe). 13C NMR (δ, CDCl3): 351.0 (t, 2JCP = 14.5 Hz, CR); 192.3
(CdO); 168.5 (Cβ); 144.4ꢀ121.5 (Ph); 95.5 (Cp); 53.3 (OMe); 49.6
Synthesis of 12b. To a solution of 11b (0.22 g, 0.22 mmol) in 5 mL
of CH3CN was added a solution of n-Bu4NOH (2.2 mL, 1 M in MeOH).
The mixture was stirred for 2 min at room temperature, and an orange
precipitate formed, which was filtered, washed with 2 ꢁ 5 mL of CH3CN
and 2 ꢁ 10 mL of diethyl ether, and dried under vacuum. The product
2
(OCH). 31P NMR (δ, CDCl3): 41.69, 39.84 (2 d, JPP = 26.6 Hz, 2
PPh3). Spectroscopic data for 15a: are as follows. 1H NMR (δ, CDCl3):
9.93 (OH); 7.68ꢀ6.31 (m, 34H, Ph); 5.34 (s, 5H, Cp); 3.66 (s, 3H,
2
OMe). 13C NMR (δ, CDCl3): 365.0 (t, JCP = 15.9 Hz, CR);
144.4ꢀ121.5 (Ph); 95.7 (Cp); 53.5 (OMe); 49.6 (OCH). 31P NMR
(δ, CDCl3): 39.97 (s, PPh3). The synthesis of 14b and 15b from 8b
(0.11 g, 0.12 mmol) followed the same procedure. The ratio of 14b to
15b is also 2:1 (total yield: 0.094 g, 86%). Spectroscopic data for 14b are
as follows. 1H NMR (δ, CDCl3): 7.72ꢀ6.69 (m, 34H, Ph); 5.40 (s, 5H,
Cp); 4.26 (s, 1H, CH); 4.25 (m, 1H, CH2); 4.15 (m, 1H, CH2); 1.27 (t,
JHH = 6.8 Hz, 3H, CH3). 13C NMR (δ, CDCl3): 351.5 (t, 2JCP = 16.2 Hz,
CR); 192.1 (CdO); 168.0 (Cβ); 144.2ꢀ121.5 (Ph); 95.5 (Cp); 62.5
(OCH2); 53.8 (OCH); 14.0 (CH3). 31P NMR (δ, CDCl3): 41.52, 39.60
(2 d, 2JPP = 26.2 Hz, 2 PPh3). Spectroscopic data for 15b are as follows.
1H NMR (δ, CDCl3): 7.65ꢀ6.29 (m, 34H, Ph); 5.26 (s, 5H, Cp); 4.34
1
was identified as 12b (0.17 g, 87%). Spectroscopic data for 12b: H
NMR (δ, C6D6): 7.48ꢀ6.90 (m, 35H, Ph); 5.35 (s, 1H, CH); 4.48 (s,
5H, Cp); 4.34 (s, 2H, CH2); 2.25 (s, 3H, CH3). 31P NMR (δ, C6D6):
51.50 (s, PPh3). Anal. Calcd for C53H46O2P2Ru: C, 72.51; H, 5.28.
Found: C, 72.73; H, 5.41. MS FAB: m/z 879.23 (Mþ þ 1).
Synthesis of 13b. Complex 12b (0.20 g, 0.23 mmol) was dissolved
in benzene, and the solution was stirred for 30 min under nitrogen at
room temperature. The resulting solution was dried to give complex 13b
(0.20 g) quantitatively. Complex 12b was also converted to 13b in 7 days
as a solid at room temperature. Spectroscopic data for 13b are as follows.
1H NMR (δ, C6D6): 7.46ꢀ7.03 (m, 35H, Ph); 4.33 (s, 5H, Cp); 2.96
3
3
(q, 2H, JHH = 6.8 Hz, CH2); 1.40 (t, 3H, JHH = 6.8 Hz, CH3). 13C
NMR (δ, CDCl3): 365.9 (t, 2JCP = 16.2 Hz, CR); 144.2ꢀ121.5 (Ph and
Cβ); 95.9 (Cp); 63.0 (OCH2); 14.7 (CH3). 31P NMR (δ, CDCl3):
39.44 (s, PPh3). The synthesis of 14c and 15c from 8c (total yield: 0.090
g, 83%) followed the same procedure (yield: 0.10 g, 0.10 mmol). The
ratio of 14c to 15c is 2.5:1. Spectroscopic data for 14c are as follows. 1H
NMR (δ, CDCl3): 7.72ꢀ6.69 (m, 39H, Ph); 5.17 (s, 5H, Cp); 5.31, 5.07
(m, 1H, 3JHH = 7.5, 6.0 Hz, CH); 2.82 (dd, 1H, 2JHH = 13.7 Hz, 3JHH
=
6.0 Hz, CH2); 2.46 (dd, 1H, 2JHH = 13.7 Hz, 3JHH = 7.5 Hz, CH2); 1.63
(s, 3H, CH3). 13C NMR (δ, C6D6): 181.2 (CdO); 169.9 (t, 2JCP = 19.1
Hz, CR); 140.6ꢀ126.1 (Ph); 123.3 (Cβ); 84.4 (Cp); 50.1 (Cγ); 37.6
(CH2); 15.3 (Me). 31P NMR (δ, C6D6): 53.31, 48.42 (2 d, 2JPP = 37.9
Hz, 2 PPh3). IR (KBr, cmꢀ1): ν 1746 (CdO). Anal. Calcd for
C53H46O2P2Ru: C, 72.51; H, 5.28. Found: C, 72.38; H, 5.19. MS
FAB: m/z 879.23 (Mþ þ 1).
2
(2d, 2H, JHH = 12.3 Hz, CH2); 4.19 (s, 1H, CH). 13C NMR (δ,
2
CDCl3): 350.8 (t, JCP = 14.0 Hz, CR); 192.4 (CdO); 168.3 (Cβ);
Synthesis of 13c. To a solution of 11c (0.20 g, 0.21 mmol) in 5 mL
of CH3CN was added a solution of n-Bu4NOH (3.0 mL, 1 M in MeOH).
The mixture was stirred for 5 min at room temperature and yielded a
yellow precipitate, which was filtered, washed with 2 ꢁ 5 mL of CH3CN
and 2 ꢁ 10 mL of diethyl ether, and dried under vacuum. The product
was then extracted with benzene (5 mL) and dried under vacuum to
yield 13c (0.14 g, 84%). Spectroscopic data for 13c are as follows. 1H
NMR (δ, C6D6): 7.55ꢀ7.04 (m, 30H, Ph); 4.90 (dd, 1H, 3JHH = 8.0 Hz,
4JHH = 6.6 Hz, dCH); 4.77ꢀ4.70 (m, 2H, CH2); 4.48 (s, 5H, Cp); 3.53
(d, 1H, 3JHH = 8.0 Hz, CH); 2.05 (s, 3H, CH3). 13C NMR (δ, C6D6):
144.2ꢀ121.6 (Ph); 95.4 (Cp); 62.7 (OCH2); 53.6 (OCH). 31P NMR
2
(δ, CDCl3): 41.86, 39.45 (2d, JPP = 26.1 Hz, 2 PPh3). MS ESI: m/z
1
987.2 (Mþ). Spectroscopic data for 15c are as follows. H NMR (δ,
CDCl3): 9.30 (OH); 7.73ꢀ6.38 (m, 39H, Ph); 5.38 (s, 2H, CH2Ph);
5.23 (s, 5H, Cp). 31P NMR (δ, CDCl3): 39.58 (s, 2 PPh3).
Reactions of 8a,c with MeI. In a Schlenk flask charged with 8a
(0.10 g, 0.11 mmol) and 15 mL of dichloromethane was added MeI
(15.0 μL, 0.24 mmol) under nitrogen. The mixture was stirred at room
temperature for 2 days. Then, the solution was filtered through Celite to
remove the insoluble precipitates, the volatiles were removed under
vacuum, and the solid residue was extracted with dichloromethane
followed by reprecipitation by adding the extract to 60 mL of stirred
diethyl ether/hexane (1/1). The precipitate thus formed was collected
on a glass frit, washed with diethyl ether, and dried under vacuum to give
the final product 16a as a brown powder (0.092 g, 79% yield). Spectro-
scopic data for 16a are as follows. 1H NMR (δ, CDCl3): 7.25ꢀ6.23 (m,
2
210.2 (dCd); 179.7 (CdO); 171.3 (t, JCP = 19.4 Hz, CR);
140.4ꢀ127.4 (Ph); 121.6 (Cβ); 89.1 (dCH); 84.4 (Cp); 76.0
(dCH2); 49.7 (CγH); 14.6 (Me). 31P NMR (δ, C6D6): 50.92, 50.54
(2 d, 2JPP = 37.1 Hz, PPh3). Anal. Calcd for C49H42O2P2Ru: C, 71.26; H,
5.13. Found: C, 71.08; H, 5.17. MS FAB: m/z 827.15 (Mþ þ 1).
Synthesis of 13d. Complex 13d was similarly prepared from a
mixture of 11d and [[Ru]dCdC(Me)CH2C(Me)dCH2][PF6] (9:1,
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dx.doi.org/10.1021/om200143e |Organometallics 2011, 30, 2747–2754

Organometallics
ARTICLE
34H, Ph); 5.35 (s, 5H, Cp); 3.73 (s, 3H, OMe); 1.49 (s, 3H, CH3). 13
C
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NMR (δ, CDCl3): 357.4 (t, 2JCP = 14.0 Hz, CR); 197.0 (CdO); 172.0
(Cγ); 143.4ꢀ125.7 (Ph and Cβ); 95.5 (Cp); 57.7 (OMe); 53.5
2
(CCH3); 21.1 (CH3). 31P NMR (δ, CDCl3): 39.71, 39.36 (2 d, JPP
= 27.5 Hz, 2 PPh3). Anal. Calcd for C54H45IO3P2Ru: C, 62.86; H, 4.40.
Found: C, 60.41; H, 3.93 (deviations may be due to the presence of both
I and I3 anion). MS ESI: m/z 905.2 (Mþ þ 1). The synthesis of 16c
(0.093 g, 81% yield) followed the same procedure from 8c (0.10 g, 0.10
mmol). Spectroscopic data for 16c are as follows. 1H NMR (δ, CDCl3):
7.37ꢀ6.25 (m, 39H, Ph); 5.20 (s, 5H, Cp); 5.27, 5.19 (2 d, 2H, 2JHH
=
12.6 Hz); 1.47 (s, 3H, CH3). 13C NMR (δ, CDCl3): 357.1 (t, 2JCP = 12.8
Hz, CR); 196.9 (CdO); 171.5 (Cγ); 143.3ꢀ125.6 (Ph and Cβ); 95.3
(Cp); 67.8 (CH2Ph); 57.7 (CCH3); 20.7 (CH3). 31P NMR (δ, CDCl3):
39.77, 39.05 (2 d, 2JPP = 27.0 Hz, 2 PPh3). Anal. Calcd for C60H49IO3-
P2Ru: C, 65.04; H, 4.46. Found: C, 61.42; H, 3.85 (deviations may be
due to the presence of both I and I3 anions). MS ESI: m/z 981.11 (Mþ).
’ ASSOCIATED CONTENT
S
Supporting Information. A CIF file giving crystallo-
b
graphic data for complex 8c. This material is available free of
charge via the Internet at http://pubs.acs.org.
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J.; Pikul, S. Tetrahedron Lett. 1985, 26, 3039–3040.
’ AUTHOR INFORMATION
(14) Faitfax, D. J.; Austin, D. J.; Xu, S. L.; Padwa, A. J. Chem. Soc.,
Perkin Trans. 1 1992, 2837–2844.
Corresponding Author
*E-mail: yclin@ntu.edu.tw.
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’ ACKNOWLEDGMENT
This research was supported by the National Science Council
and National Center of High-Performance Computing of
Taiwan, Republic of China.
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