Stoichiometric and catalytic cross dimerization between conjugated dienes and conjugated carbonyls by a ruthenium(0) complex: Straightforward access to unsaturated carbonyl compounds by an oxidative coupling mechanism

Article abstract of DOI:10.1021/om300234d

A series of stoichiometric and catalytic cross dimerizations between conjugated dienes and conjugated carbonyls are studied. The reaction of Ru(η⁴-cisoid-1,3-butadiene)(η⁴-1,5-COD)(NCMe) (2a) with methyl acrylate gives a Ru(0) complex, Ru[methyl η⁴-cisoid- (2E,4E)-hepta-2,4-dienoate](η⁴-1,5-COD)(NCMe) (3aa) in 97% yield. Similar treatments of 2a with a series of tert-butyl acrylate, methyl crotonate, 3-buten-2-one, and N,N-dimethylacrylamide produce similar analogues of 3ac. When (E)-1,3-pentadiene complex 2d is employed in the reaction with methyl acrylate, the branched coupling product Ru[methyl η⁴- cisoid-(2E,4E)-4-methylhepta-2,4-dienoate](η⁴-1,5-COD)(NCMe) (3da-b) is dominantly obtained in 65% yield along with the linear product in 19% yield. In the case of the (E)-2,5-dimethylhexa-1,3-diene complex 2e, the corresponding branch product is exclusively obtained in 86% yield. The catalytic cross dimerizations between conjugated dienes and conjugated carbonyls are established by 2. The origin of the present chemoselectivity is the η⁴-coordination of a conjugated diene and η²- coordination of an electron-deficient alkene to formal 6e coordination sites at Ru(0), and the regioselectivity being prone to giving branched products is interpreted as an oxidative coupling mechanism, involving nucleophilic attack of the coordinated diene to the coordinated electron-deficient alkene.

Full text of DOI:10.1021/om300234d

Article
pubs.acs.org/Organometallics
Stoichiometric and Catalytic Cross Dimerization between
Conjugated Dienes and Conjugated Carbonyls by a Ruthenium(0)
Complex: Straightforward Access to Unsaturated Carbonyl
Compounds by an Oxidative Coupling Mechanism
Masafumi Hirano,* Yasutomo Arai, Yuka Hamamura, Nobuyuki Komine, and Sanshiro Komiya
Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology,
2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
S
* Supporting Information
ABSTRACT: A series of stoichiometric and catalytic cross di-
merizations between conjugated dienes and conjugated carbonyls
are studied. The reaction of Ru(η4-cisoid-1,3-butadiene)(η4-1,5-
COD)(NCMe) (2a) with methyl acrylate gives a Ru(0) complex,
Ru[methyl η4-cisoid-(2E,4E)-hepta-2,4-dienoate](η4-1,5-COD)-
(NCMe) (3aa) in 97% yield. Similar treatments of 2a with a
series of tert-butyl acrylate, methyl crotonate, 3-buten-2-one, and
N,N-dimethylacrylamide produce similar analogues of 3ac. When
(E)-1,3-pentadiene complex 2d is employed in the reaction with
methyl acrylate, the branched coupling product Ru[methyl η4-cisoid-(2E,4E)-4-methylhepta-2,4-dienoate](η4-1,5-COD)(NCMe)
(3da-b) is dominantly obtained in 65% yield along with the linear product in 19% yield. In the case of the (E)-2,5-dimethylhexa-
1,3-diene complex 2e, the corresponding branch product is exclusively obtained in 86% yield. The catalytic cross dimerizations
between conjugated dienes and conjugated carbonyls are established by 2. The origin of the present chemoselectivity is the
η4-coordination of a conjugated diene and η2-coordination of an electron-deficient alkene to formal 6e coordination sites at
Ru(0), and the regioselectivity being prone to giving branched products is interpreted as an oxidative coupling mechanism,
involving nucleophilic attack of the coordinated diene to the coordinated electron-deficient alkene.
Chart 1. Methyl Heptadienoates (MHD) by Cross
Dimerization between 1,3-Butadiene and Methyl Acrylate
INTRODUCTION
■
One promising and valuable use of olefin dimerization is the
chemoselective cross dimerization of substituted olefins, since it
would provide an easy and versatile synthetic methodology for
a variety of highly functionalized organic molecules. Cationic
and neutral Ru(II) complexes having a Cp or Cp* ligand are
known to catalyze cross dimerization reactions among con-
jugated dienes, electron-rich olefins, distorted olefins, and
alkynes.1 Such processes are undoubtedly important, but they
often fail when applied to electron-deficient alkenes in general,
owing to the formal oxidation state of the metal center.2
We previously reported the high reactivity of Ru(η6-naphthalene)-
(η4-1,5-COD) (1) toward oxidative coupling reactions3 such
as the catalytic tail-to-tail dimerization of methyl acrylate4
and methyl methacrylate,5 chemo- and diasteroselective cross
dimerization of methyl methacrylate and 2,5-dihydrofuran,6 and
stoichiometric stereoselective coupling of conjugated dienes.7
In the line of exploration assessment, we found and communi-
cated the reaction of Ru(η4-cisoid-1,3-butadiene)(η4-1,5-COD)-
(NCMe) (2a) with methyl acrylate to produce Ru[methyl
cisoid-η4-(2E,4E)-hepta-2,4-dienoate](η4-1,5-COD)(NCMe)
(3aa) in quantitative yield, which catalyzed the cross dimer-
ization of 1,3-butadiene and methyl acrylate to give a mixture of
(2E,5Z)-MHD and (2E,4E)-MHD (Chart 1).8
The cross dimerization between 1,3-butadiene and methyl
acrylate has a long history extending back to the first brief
report by Witternberg of a diene complex of Co giving 4,6-
MHD; however, it fails to address the details of the catalyst
and stereoselectivity.9 Uchida and co-workers documented a
compelling example reporting the treatment of Fe(acac)3 or
Co(acac)3 with AlEt3 to give 2,5-MHD and 3,5-MHD.10 The
Fe(acac)3/AlEt3 system was modified to give (2Z,5Z)-MHD
and (2E,5Z)-MHD in 1:1 ratio by the addition of Sb(OPh)3,11
or (2Z,5Z)-MHD exclusively in the presence of SbPh3.12
Received: March 21, 2012
Published: May 10, 2012
© 2012 American Chemical Society
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Branching out from Ziegler-type systems, Wilke and co-workers
demonstrated that a “naked cobalt” catalyst displayed poor
activity, but CoH(η4-1,5-COD)2 and its equilibrium isomer
Co(η1:η2-cyclooct-4-ene-1-yl)(η4-1,5-COD) effectively catalyzed
the reaction quantitatively, giving a 4:1 mixture of (2E,5Z)-MHD
and (E)-4,6-MHD.13 The related Co(η3-cyclooctenyl)(η4-1,5-
COD) catalyst was reported to give a 24:1 mixture of (2E,5Z)-
MHD and (E)-4,6-MHD in hexane.14 The first Ru system was
communicated by Mitsudo and co-workers wherein a Ru(0)
complex, Ru(η4-1,5-COD)(η6-1,3,5-COT), produces methyl
(3E,5Z)-MHD and (2E,5Z)-MHD in a 80:20 ratio.15 In all
cases, these pioneering examples, including the Ru(η4-1,5-
COD)(η6-1,3,5-COT) system, are proposed to proceed by a
so-called “hydrido insertion mechanism” with some support-
ing evidence.16
The formation process of 3aa obviously involves a C−C
bond-forming step between 1,3-butadiene and methyl acrylate
and migration steps of the hydrogen atoms. In order to un-
derstand the pathway of hydrogen migration, the naphthalene
complex 1 was treated with [1,1,4,4-2H4]-1,3-butadiene (1,3-
butadiene-d4) (>98 atom % D) in the presence of acetonitrile
to give an isotopically labeled 1,3-butadiene complex. These
four deuterium atoms in the 1,3-butadiene ligand were un-
expectedly distributed among endo-methylene protons in the
1,5-COD ligand of 2a-d4 (Scheme 1).
Scheme 1
Herein we disclose a full account of the stoichiometric and
catalytic cross dimerization reactions between conjugated dienes
and conjugated carbonyls promoted by Ru(η4-conjugated diene)-
(η4-1,5-COD)(NCMe). The present system offers several
advantages over these pioneering systems to give perfect
cross selectivity, high tolerance of functional groups, and
high branch selectivity for substituted dienes by an oxidative
coupling mechanism.
Although we do not reveal mechanistic details of this pro-
cess, we previously documented similar endo-methylene
selective deuteration of the 1,5-COD ligand in [RuD(η6-9,10-
dihydroanthracene)(η4-1,5-COD)]PF6.19 Thus, one of the
possible mechanisms for this H/D exchange reaction is C−H
bond oxidative addition of a methylene group in the 1,5-COD
ligand, giving RuH(η4-CD2CHCHCD2)(η5-C8H11), which
reversibly isomerizes to Ru(η3-CD2CHCHCD2H)(η5-C8H11).
By this rapid reversible process, the D atoms in the butadiene
ligand exchange with the endo-methylene protons in the 1,5-
COD ligand, and the deuterium content drops to a statistical 50
atom % D.
Treatment of 2a-d4 with methyl acrylate gave the 2,4-MHD
complex 3aa-d4, where the deuterium atoms were exclusively
distributed among the 4- and 5-methines (50 atom % D) and 7-
methyl (33 atom % D), in addition to the endo-methylenes
(50 atom % D) in the 1,5-COD ligand.
RESULTS AND DISCUSSION
■
1. Reactions of (η4-cisoid-1,3-Butadiene)ruthenium(0)
with Substituted Alkenes. A few conjugated diene com-
plexes of Ru(0) containing a 1,5-COD ligand were prepared
by Bennett et al.,17 and in a recent collaborative article, we
reported the preparation, molecular structures, and properties
of an additional series of conjugated diene complexes.18 Con-
versely, we found that treatment of Ru(η4-cisoid-1,3-butadiene)-
(η4-1,5-COD)(NCMe) (2a) with methyl acrylate (e = 0.64) in
benzene at 6 °C for 3 h produced the Ru(0) complex
Ru[methyl cisoid-η4-(2E,4E)-hepta-2,4-dienoate](η4-1,5-COD)-
(NCMe) (3aa), which was isolated as an air-sensitive brown oil
in 97% yield (eq 1).
For a further understanding of this reaction, we have
screened the reactivity of substituted alkenes as summarized in
Scheme 2.
Compound 2a readily reacts with 3-butene-2-one, tert-butyl
acrylate, and N,N-dimethylacrylamide (e = −0.26) to give
similar coupling products of Ru(0). Of particular interest is the
immediate formation of the branched diene compound 3ad
by the reaction of 2a with methyl (E)-2-butenoate as a 1,2-
disubstituted electron-deficient alkene. On the other hand,
treatment of 2a with methyl methacrylate (e = 0.40), a 1,1-
disubstituted electron-deficient alkene, was sluggish and
eventually afforded a complex mixture. The reactions of 2a
with styrene (e = −0.80) and ethyl vinyl ether (e = −1.80) were
also very slow and ultimately produced a mixture of uniden-
tified products.
1
1
Complex 3aa was characterized by H NMR and H−1H
COSY spectroscopy and interestingly indicated that an ethyl
group is attached to the conjugated diene moiety. In the H
1
NMR spectrum, the methylene protons of the ethylene
fragment are observed to be diastereotopic at δ 1.30 (dquint)
and 1.48 (dquint). The correlated 1H resonances at δ 1.22 (q),
1.39 (d), 4.86 (dd), and 6.10 (dd) are assigned as the 5-CH,
2-CH, 4-CH, and 3-CH protons, respectively. The characteristic
3H resonances at δ 0.82 (s) and 3.49 (s) are assignable to the
acetonitrile and the methyl ester fragments, respectively. These
observations are consistent with the formation of the methyl
cisoid-η4-(2E,4E)-hepta-2,4-dienoate fragment at the ruthenium
center. The formation of the conjugated diene moiety was also
confirmed by the chemical reactions described below.
When vinyl acetate (e = −0.88) was employed in this
reaction, formation of a thermally unstable coupling product,
Ru[(η3-CH2CHCH)CH2CH2{C1H(OC(O1)Me-η1C1,κ1O1)}]-
(η4-1,5-COD)(NCMe) (3af), was observed, which was
1
1
characterized by H NMR, H−1H COSY, 13C{1H} NMR,
and 13C−1H HETCOR spectroscopic methods. The 13C{1H}
NMR spectrum displayed 16 resonances, suggesting all carbon
atoms are inequivalent. One of the characteristic features of 3af
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α-methine proton in CH{OC(O)Me} fragments. A high-field
shift of one of the methine protons in the 1,5-COD ligand
at δ 0.68 is probably due to the shielding effect caused by
π-electrons in the closely neighboring carbonyl group.
Scheme 2. Reactions of a 1,3-Butadiene Complex with
Substituted Olefins
Taking into account these features, it is reasonable to pos-
tulate the contribution of the (acetato)(carbene) ruthenium(II)
resonance extreme in 3af (eq 2). The reason for the thermal
instability of 3af is not clear to date, but one of the possible
reasons is the formation of the reactive carbene complex by this
α-acetato elimination.22
According to the results in this section, the treatment of 1,3-
butadiene complex 2a with conjugated carbonyl compounds
produced a series of conjugated diene-carbonyl complexes of
ruthenium(0). In the case of the reaction of 2a with vinyl
acetate, an η1:η3-ruthenacycle was obtained.
2. Reactions of a Series of (η4-cisoid-Diene)ruthenium-
(0) with Conjugated Carbonyls. Similar treatment of the
isoprene analogue 2b with 3-buten-2-one or N,N-dimethyla-
crylamide produces the related conjugated diene complexes of
Ru(0) having a carbonyl group in the conjugated position in
46−59% yields (Scheme 3). Comparatively, similar treatment
of the 2,3-dimethylbutadiene complex 2c with conjugated
carbonyl compounds gave the coupling products 3ca, 3cb, and
3ce, but subsequent conjugation of the carbonyl groups with
the diene fragments was not observed. In fact, the IR spectra of
3aa and 3ca display the ν(CO) band at 1685 and 1730 cm−1,
respectively, suggesting stabilization by strong conjugation of
the carbonyl group with the diene fragment in 3aa. Never-
theless, 3ca disfavors the 2,4-diene-carbonyl structure. This
probably arises from steric repulsion between an endo sub-
stituent and the methine proton in cisoid-2,4- and cisoid-3,5-
diene carbonyl ligands (Chart 2).
In order to understand this system’s preference for non-
conjugated products, DFT calculations (B3LYP/6-31G*) have
been performed. As shown in Chart 3, Ru[methyl cisoid-η4-
(2E,4E)-hepta-2,4-dienoate](η4-1,5-COD)(NCMe) (3aa), hav-
ing a conjugated carbonyl group, is 42.6 kJ mol−1 more stable
than the terminal diene complex Ru[methyl cisoid-η4-(4E,6E)-
hepta-4,6-dienoate](η4-1,5-COD)(NCMe) (3aa′). On the
other hand, the conjugated carbonyl complex Ru[methyl
cisoid-η4-(2E,4E)-5,6-dimethylhepta-2,4-dienoate](η4-1,5-
COD)(NCMe) (3ca′) is 30.0 kJ mol−1 less stable than the
most stable terminal diene complex, Ru[methyl cisoid-η4-(4E)-
5,6-dimethylhepta-4,6-dienoate](η4-1,5-COD)(NCMe) (3ca).
These thermodynamic analyses help us to understand this
experimental result.
To our surprise, when the 1,3-pentadiene complex 2d reacted
with conjugated carbonyls, the C−C bond-forming reactions
primarily took place at the 4-position of the 1,3-pentadiene,
giving branched products 3da-b, 3db-b, and 3de-b in 41−65%
yields, along with the minor linear regioisomers 3da-l, 3db-l, and
3de-l in 4−21% yields (Scheme 3). The DFT calculations of 2d
and the putative key intermediates Ru[cisoid-η4-(E)-1,3-
pentadiene](η2-methyl acrylate)(η4-1,5-COD) (2dMA) indi-
cate that the 4-position of the 1,3-pentadiene fragment has
significantly larger HOMO coefficients than the 1-position in
in the 1H NMR is four allylic resonances at δ 2.28 (td), 2.73 (d),
3.82 (d), and 4.38 (ddd), with coupling constants suggesting
anti stereochemistry of the monosubstituted allylic group.
Moreover, a slightly broad singlet assignable to C1H was
observed at δ 7.74. Although this resonance appeared as a
slightly broad singlet, 1H−1H COSY analysis indicated the spin
correlation between this resonance and the diastereotopic
resonances at δ 3.19 (C2H2, 1H) and 3.27 (C2H2, 1H). Thus,
this resonance is assigned as C1H{OC(O)Me}. The low-field
resonance of these α-methine protons in the Ru-CH{OC(O)-
Me} fragment seems to be a common feature, whereas those in
[Ru{C1H(Me)OC(O1)Et-η1C1,κ1O1}(SO3CF3)(CO)2]2 and
RuCp[C1H{OC(O1)Me}(CO2Et)-η1C1,κ1O1](PPh3) were
20
documented to appear at δ 6.45 (q) in THF-d8 and δ 6.29
(d) in toluene-d8,21 respectively. We therefore concluded that a
low-field resonance is a common characteristic feature for the
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Scheme 3. Reactions of Branched Conjugated Diene Complexes with Conjugated Carbonyls
A branched product, 3ea, was exclusively obtained when we
employed (cisoid-η4-2,5-dimethylhexa-1,3-diene)ruthenium(0)
(2e) in this reaction. Despite the large steric congestion, this
observation implies their electron-deficient alkene favors attack
at the diene carbon having an isopropyl group in 2e. We also
conclude that this exclusive regioselectivity is achieved by
significant induction effects of the isopropyl group in 2e.
To summarize, electronic factors likely govern the regio-
selectivity in the carbon−carbon bond-forming reaction, which
involves nucleophilic attack of the Ru(0)-coordinated 1,3-diene
on the coordinated electron-deficient alkene. Thermodynamic
stability of the coupled products determined the regiochemistry
of the CC bond.
Chart 2. Potential Regioisomers of 3ca
3. Molecular Structures of Diene Complexes. As
described above, the coupling product 3aa was obtained as
an oil. In our previous communication, we have reported the
molecular structures of Ru[methyl cisoid-η4-(2E,4E)-hepta-2,4-
dienoate](η4-1,5-COD)(CO) (3aaCO) and also Ru[methyl
cisoid-η4-(2E,4E)-hepta-2,4-dienoate](η4-1,5-COD)(PPh3)
(3aaPPh3) in the Supporting Information. In this article, we
report the structures of related compounds. Although single
both cases (Figure 1). Since the present system favors electron-
deficient alkenes as described below, the Me group in the 1,3-
pentadiene fragment enhances the susceptibility toward
electrophilic attack at the 4-position through induction effects.
For 2dMA, strong interaction with the same phase among the
4-position in 1,3-pentadiene, Ru, and the β-carbon in methyl
acrylate is demonstrated in the HOMO level. This scenario is
consistent with the product selectivity for 2d.
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recrystallization in cold Et2O. They are depicted in Figure 2,
and the selected bond distances and angles are listed in Table 1.23
Although the structure analysis of 3ea is not of high preci-
sion, the essential features of the structure are evident. The
revealed molecular structure indicates a C−C bond-forming
Chart 3. Relative Thermodynamic Stability between
Regioisomers for 3aa and 3ca
Figure 1. Orbital diagrams showing the HOMO for Ru{cisoid-η4-(E)-
1,3-pentadiene}(η4-1,5-COD)(NCMe) (2d) (left) and Ru[cisoid-η4-
(E)-1,3-pentadiene](η2-methyl acrylate)(η4-1,5-COD) (2dMA)
(right).
crystals of 3ae suitable for X-ray structure analysis could not be
obtained, its PPh3 analogue 3aePPh3 produced suitable crystals
grown in cold Et2O. Similarly, single crystals of the stoichio-
metric coupling product between the 2,3-dimethylbutadiene
complex 2c and methyl acrylate 3ca were also obtained by
Figure 2. Molecular structures of 3aePPh3, 3ca, and 3ea with selected
numbering schemes. All hydrogen atoms are omitted for clarity.
Ellipsoids represent 50% probability. These crystallographic and
refinement details are summarized in Table 3.
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are only −0.013 Å for 3aePPh3 and 0.006 Å for 3ca and lie in
the range −0.1 < Δd < +0.1 Å. Moreover, the external C−Ru−
C angles (α) [C(3)−Ru(1)−C(6) for 3aePPh3: 77.77(8)°,
C(1)−Ru(1)−C(4) for 3ca: 77.9(4)°] lie between 75° and
Table 1. Selected Bond Distances (Å) and Angles (deg) for
3aePPh3, 3ca, and 3ea
3aePPh3
90°. Thus, according to Muller’s distinguish method,24 the
Ru(1)−P(1)
Ru(1)−C(4)
Ru(1)−C(6)
C(4)−C(5)
C(6)−C(7)
N(1)−C(7)
C(3)−Ru(1)−C(6)
C(3)−C(4)−C(5)
C(5)−C(6)−C(7)
O(1)−C(7)−C(6)
2.4350(5)
2.193(2)
2.284(2)
1.407(3)
1.483(2)
1.357(3)
77.77(8)
120.5(2)
Ru(1)−C(3)
Ru(1)−C(5)
C(3)−C(4)
C(5)−C(6)
O(1)−C(7)
2.235(2)
2.193(2)
1.407(3)
1.427(3)
1.236(3)
̈
main contributors to the bonding in 3aePPh3 and 3ca are not
the ene-diyl but the diene extreme. Although the dihedral angles
for C(5)−C(6)−C(7)−O(1) [−16.8(3)°] and C(5)−C(6)−
C(7)−N(1) [164.3(2)°] in 3aePPh3 showed slight deviations
out of the plane of the coordinating diene fragment, these
groups are likely to conjugate with the diene fragment.
4. Reactions of Diene Complexes. As a typical example
for characterization of the coupling products by chemical
reactions, a series of reactions of 3aa and the PPh3 analogue
3aaPPh3 are described in this section.
Ru(1)−C(3)−C(4)
C(4)−C(5)−C(6)
69.85(13)
120.0(2)
119.2(2)
−5.5(3)
116.23(19) O(1)−C(7)−N(1)
121.8(2)
C(3)−C(4)−C(5)−
C(6)
C(4)−C(5)−C(6)−C(7) 177.2(2)
C(5)−C(6)−C(7)−
−16.8(3)
O(1)
As summarized in Scheme 4, iodolysis of 3aa and 3aaPPh3
instantly liberated (2E,4E)-MHD in 80% and 81% yields,
respectively, which was confirmed by the authentic sample.25
Thermolysis of 3aa in benzene at 70 °C gave a complex
mixture, but that of 3aaPPh3 quantitatively produced Ru-
(methyl anti,anti-η3-hept-4-enoate-3-yl)(η5-cyclohexa-2,4-diene-
1-yl) (6), which was characterized by 1H NMR, 1H−1H COSY,
13C NMR, NOESY, 13C−1H HETCOR, and HOHAHA26
C(5)−C(6)−C(7)−N(1) 164.3(2)
3ca
Ru(1)−N(1)
Ru(1)−C(2)
Ru(1)−C(4)
C(2)−C(3)
C(4)−C(5)
C(6)−C(7)
O(2)−C(7)
2.119(4)
2.203(5)
2.181(4)
1.428(5)
1.512(5)
1.501(6)
1.334(5)
Ru(1)−C(1)
Ru(1)−C(3)
C(1)−C(2)
C(3)−C(4)
C(5)−C(6)
O(1)−C(7)
2.160(5)
2.218(5)
1.420(6)
1.422(6)
1.529(7)
1.187(5)
1
spectroscopic methods. A set of characteristic correlated H
resonances at δ 4.72 (t, J = 9.0 Hz), 1.77 (t, J = 9.0 Hz) and an
overlapping resonance around δ 1.16−1.23 are assignable to the
three allylic protons, and the central allylic proton (4-CH) at δ
4.72 is coupled with two allylic protons (3JH−H = 9.0 Hz). The
3JH−H coupling constants for the syn and anti protons in the η3-
allylic group (7 and 11 Hz) are typical,27 while the coupling
constants of 6 could not be resolved. Since the NOESY
spectrum of 6 displayed very weak correlating signals among 3-
CH, 4-CH, and 5-CH protons, we tentatively assign 6 as the
anti product. The methylene protons at 2- and 6-CH2 are ob-
served as diastereotopic, suggesting this fragment coordinates
to the Ru center. The correlated 5-methine protons are assigned
to the 1,5-η5-cyclooctadienyl ligand.
Compound 6 is probably formed by proton migration from
the 1,5-COD ligand to the methyl heptadienoate ligand. The
most notable reaction is liberation of (2E,4E)-MHD by expo-
sure of 3aaPPh3 to 1,3-butadiene, where a butadiene complex
of Ru(0), 2aPPh3, has been reproduced. This stoichiometric
reaction promises the catalytic cross dimerization process. In
the case of the reaction of 3aa with 1,3-butadiene, supine,prone-
Ru(η3:η3-octa-2,6-diene-1,8-diyl)(η4-1,5-COD) (supine,prone-5)
was obtained in 54% yield along with (2E,4E)-MHD. We have
reported formation of supine,prone-5 by the treatment of 1 with
an excess amount of 1,3-butadiene through Ru(cisoid-η4-1,3-
butadiene)(transoid-η2-1,3-butadiene)(η4-1,5-COD) as the in-
termediate.7 Therefore, this reported reaction between 3aa and
1,3-butadiene probably results in the re-formation of 2a with
liberation of (2E,4E)-MHD, and 2a successively converts into
supine,prone-5.
C(1)−Ru(1)−C(4)
C(2)−C(3)−C(4)
C(4)−C(5)−C(6)
O(1)−C(7)−C(6)
78.39(15) C(1)−C(2)−C(3)
117.3(4)
121.6(4)
113.3(4)
123.4(4)
172.4(4)
117.8(4)
114.0(4)
125.9(4)
C(3)−C(4)−C(5)
C(5)−C(6)−C(7)
O(1)−C(7)−O(2)
C(1)−C(2)−C(3)−C(4) −177.9(4) C(2)−C(3)−C(4)−
C(5)
C(3)−C(4)−C(5)−C(6) 83.2(5)
C(4)−C(5)−C(6)−
−172.6(4)
C(7)
3ea
Ru(1)−N(1)
Ru(1)−C(2)
Ru(1)−C(4)
C(2)−C(3)
C(4)−C(5)
O(2)−C(5)
C(2)−C(10)
2.108(9)
Ru(1)−C(1)
2.223(10)
2.176(9)
2.233(11) Ru(1)−C(3)
2.197(10) C(1)−C(2)
1.422(13) C(3)−C(4)
1.478(13) O(1)−C(5)
1.336(13) C(1)−C(7)
1.515(15)
1.443(15)
1.423(14)
1.235(13)
1.521(14)
C(1)−Ru(1)−C(4)
C(2)−C(3)−C(4)
O(1)−C(5)−C(4)
C(8)−C(7)−C(9)
77.9(4)
C(1)−C(2)−C(3)
C(3)−C(4)−C(5)
O(1)−C(5)−O(2)
115.8(9)
118.6(9)
124.8(9)
120.8(9)
124.4(9)
108.8(10) C(11)−C(10)−C(12) 108.1(10)
C(1)−C(2)−C(3)−C(4) −1.4(14) C(2)−C(3)−C(4)−
−179.9(8)
C(5)
C(3)−C(4)−C(5)−O(1) −18.0(15)
product at the more congested side in 2e with methyl acrylate.
The unit cell contains two crystallographically independent
molecules, one of which is depicted in Figure 2. The metrical
data are listed in Table 1 (the second molecule displays similar
structural properties). This is consistent with the structural
conclusion hypothesized from NMR spectral data.
As expected by NMR spectroscopy, complex 3aePPh3 has
the carbonyl group in a conjugated position relative to the
diene, while the carbonyl group in 3ca is devoid of diene
conjugation. The bond distances for the formal C−C single
bond in these cisoid diene fragment [1.407(3) Å for 3aePPh3,
1.428(5) Å for 3ca] are almost the same as those for the formal
CC double bond [1.407(3) and 1.427(3) Å for 3aePPh3,
1.420(6) and 1.422(6) Å for 3ca], and those differences (Δd)
5. Catalytic Cross Dimerization between Conjugated
Dienes and Conjugated Carbonyls. Catalytic reactions
between conjugated dienes and conjugated carbonyls have been
screened. The rate of catalysis at room temperature was very
sluggish, and the yield decreased at high temperature due to
catalyst deactivation. With the optimized reaction conditions,
the scope of the Ru(0)-catalyzed cross dimerization reaction with
respect to various conjugated dienes and conjugated carbonyls
was investigated (Table 2).
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b
Table 2. Ru(0)-Catalyzed Cross Dimerization between Conjugated Dienes and Conjugated Carbonyls
a
b
A 1:1 mixture of (2E,4E)-2,4-hexadiene and (2E,4Z)-2,4-hexadiene was used. Catalyst: 2 mol %, reaction time: 4 h, solvent: benzene. Yields were
determined by GLC based on the biphenyl as an internal standard.
The cross dimerization reaction between butadiene and methyl
acrylate proceeded by both 1,3-butadiene and methyl η4-(2E,4E)-
hepta-2,4-dienoate complexes of Ru(0) (entries 1 and 2).
As mentioned above, Mitsudo et al. reported this cross dimeri-
zation to give (3E,5Z)-MHD as a dominant product by use of a
Ru(0) complex, Ru(η4-1,5-COD)(η6-1,3,5-COT), as a catalyst
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discussed in greater detail in the next section. For the treatment
of butadiene with 3-butene-2-one, the catalytic cross dimeriza-
tion failed, while 3-hexenyl methyl ketone was produced by a
Diels−Alder reaction (entry 3). Contrary to these catalyses
using electron-deficient olefins, vinyl acetate did not react with
1,3-butadiene at all, although Fujiwara and co-workers indicated
that this reaction proceeds by RuCp*Cl(η4-1,5-COD).29 The
reaction of 2,3-dimethylbutadiene with methyl acrylate gave
cross dimers in almost quantitative total yield (entry 7). 1,3-
Pentadienes also react with conjugated carbonyls, producing
primarily branched products (entries 10−12). A 1:1 mixture of
(2E,4E)- and (2E,4Z)-2,4-hexadienes was converted into the
branched product (entry 13), although the stoichiometric
reaction between 1 and the 2,4-hexadienes produced (cisoid-
exo-η4-2,5-dimethylhexa-1,3-diene)ruthenium(0) (2e) via iso-
merization.18 Notably, myrcene, as a branched triene, can
also be used in the reaction with methyl acrylate (entry 14).
Although myrcene is prone to oligomerization by heat or even
at room temperature, this reaction proceeds quantitatively
without formation of homocoupling oligomers. Although Jolly
and co-workers reported an η4:η2-coordination of the related 2-
vinylhexa-1,5-diene in the Fe(0) center,30 our preliminary data
suggested myrcene also coordinates to Ru(0) in an η4-fashion.
It is noteworthy that such cross dimerizations between myrcene
and substituted alkenes is still limited.31,32 Catalytic trans-
formation of plant oils is one of the current topics in organo-
metallic chemistry as a renewable feedstock,33 and this reaction
opens up potential utilization of the present system for catalytic
conversion of terpenoids.
Scheme 4
6. Mechanism and the Supporting Reactions. Consid-
ering the isotopic labeling experiment and the experimental
results described above, the present coupling reaction can be
explained as summarized in Scheme 5.
precursor.15 They confirmed the in situ formation of a (hydrido)-
ruthenium(II) species28 and proposed a hydrido-insertion
mechanism. In our case however, the dominant product is
(2E,5Z)-MHD, suggesting a different mechanism. This issue is
It is reported that the naphthalene ligand in 1 is removed in
the presence of auxiliary ligand, due to the facile ring-slippage.34
a
Scheme 5. Mechanism for the Stoichiometric and Catalytic Coupling Reactions
a
Deuterium labels are shown only for explanation of trails of hydrogen migrations.
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The removal of the coordinated naphthalene ligand formally
generates a 6e coordination site at the Ru(0) center, to which
the conjugated diene (4e donor) and the alkene (2e donor)
coordinate by η4- and η2-fashions, respectively, giving B. This
coordination geometry must be the origin of the chemo-
selectivity in this cross dimerization reaction. In fact, we have
isolated similar Ru(0) compounds such as Ru(η4-cisoid-1,3-
butadiene)(η2-transoid-1,3-butadiene)(η4-1,5-COD) at low
temperature as intermediates for the formation of supine,-
prone-Ru(η3:η3-2,6-octadiene-1,8-diyl)(η4-1,5-COD).7 We have
observed formation of the η1:η3 complex 3af when vinyl acetate
is employed, which well explains the oxidative coupling
mechanism between 1,3-diene and alkene. The highly basic
Ru(0) center can be expected to enhance susceptibility toward
oxidative coupling. A similar mechanism can most likely be
applied to the conjugated carbonyls as well. Following this,
oxidative coupling occurs to give C. In the intermediate C, the
η3-allylic fragment must have anti stereochemistry because the
original butadiene ligand has a cisoid configuration. β-Hydride
elimination from C gives D, from which reductive elimination
leads to E, where the stereochemistry of the MHD ligand must
be (2E,5Z)-MHD. Such an unconjugated diene ligand must be
labile and would readily be displaced by 1,3-butadiene if this
system is operated under the catalytic conditions. This scenario
well accounts for the predominant formation of (2E,5Z)-MHD
in the present catalysis. It is less clear how 3aa is formed, but
the observed isotopic labeling experiment is consistent with the
following pathway. The intermediate E can convert into the
more thermodynamically stable conjugated compound. For
such isomerization, a C−H bond activation process must be
involved. On the basis of the deuterium labeling experiment,
the most probable process is the C−H bond oxidative addition
of the alkenyl proton at the 5-position to form an (alkenyl)-
(hydrido)ruthenium(II) species F, which isomerizes to the
carbene species G. Notably, no incorporation of deuterium
occurred at the 6-position during the formation of 3aa-d4,
suggesting selective migration of a deuterium atom from the 4-
to 5-position in the MHD ligand without scrambling. Although
such isomerization processes are rare, it is difficult to explain
such selective migration of a deuterium atom to the 5-position
in 3aa-d4 without postulation of G. Similar isomerizations from
alkenyls to carbenes are well documented.35 Next, G isomerizes
to H followed by the reductive elimination giving I. Finally,
by displacement of the (2E,4E)-MHD ligand by butadiene
produces free (2E,4E)-MHD and 3aa. Alternatively, isomer-
ization of (2E,5Z)-MHD to (2E,4E)-MHD by the in situ
formed hydride species may be a potential mechanism for the
formation of (2E,4E)-MHD. However, we believe this is fairly
unlikely because the (2E,5Z)-MHD/(2E,4E)-MHD ratio does
not become altered regardless of the reaction time.
suggested to be described as oxidative coupling. The formations
of branched coupling products and 3af underpin this
mechanism.
EXPERIMENTAL SECTION
■
General Procedures. All manipulations and reactions were
performed under dry nitrogen or argon with use of standard Schlenk
and vacuum line techniques. Benzene, toluene, hexane, pentane,
tetrahydrofuran (THF), and Et2O were distilled over sodium
benzophenone ketyl, and dichloromethane and acetonitrile were
distilled from Drierite; ethanol was dried over calcium chloride and
distilled under nitrogen from magnesium ethoxide. These solvents
were stored under a nitrogen atmosphere. 1,3-Butadiene (99.0% pure)
was purchased from Takachiho Chemical Industry and used as
received. Ru(η6-naphthalene)(η4-1,5-COD) (1) was prepared accord-
ing to the literature procedure.36 Ru(η4-cisoid-1,3-butadiene)(η4-1,5-
COD)(NCMe) (2a) and other reported conjugated diene complexes
were prepared from 1 based on the literature method.17,18 All other
reagents were obtained from commercial suppliers (Wako Pure
Chemical Industry, Aldrich, or TCI) and used as received. Benzene-d6
and toluene-d8 were dried over sodium wire, acetonitrile-d3 was dried
over Drierite, and dichloromethane-d2 was dried over P4O10, these
solvents being stored under vacuum. NMR spectra were recorded on a
JEOL LA300 (1H at 300 MHz, 31P at 122 MHz) or a JEOL ECX400P
(1H at 399.8 MHz, 13C at 100.5 MHz, 31P at 161.8 MHz) spec-
trometer. Tetramethylsilane was used as reference for 1H and 13C
spectra, and external 85% H3PO4 for 31P spectra. IR spectra were
measured on a JASCO FT/IR-4100 spectrometer. Elemental analyses
were performed on a Perkin-Elmer 2400 Series II CHN analyzer. The
GLC analyses were performed on a Shimadzu GC14B equipped with a
TC-WAX (0.25 mm ⦶ × 30 m) under the following conditions: initial
temp = 50 °C, initial time = 5 min, program rate = 5 °C/min, final
temp = 220 °C, injector temp = 200 °C, detector temp = 200 °C.
GC-MS was measured on a Shimadzu QP2010 by use of the electron
impact method. Several conjugated diene-carbonyl complexes of
Ru(0) were difficult to isolate with satisfactory elemental analysis data,
probably due to low stability. They were identified by spectroscopic
methods.
Reactions of Ru(η4-cisoid-1,3-butadiene)(η4-1,5-COD)(NCMe)
(2a) with Substituted Alkenes. With Methyl Acrylate. Into a
benzene solution (6 mL) of 2a (98.8 mg, 0.325 mmol), methyl
acrylate (30.0 μL, 0.333 mmol) was added by a hypodermic syringe,
and the solution was stirred at 6 °C for 3 h and then allowed to rise to
room temperature for an additional 3 h. After removal of all volatile
materials, Ru[methyl η4-cisoid-(2E,4E)-hepta-2,4-dienoate](η4-1,5-
COD)(NCMe) (3aa) was obtained as a brown oil in 97% yield
1
(122.5 mg, 0.314 mmol). H NMR (300 MHz, C6D6, rt): δ 0.82 (s,
1H, NCMe), 0.99 (t, 3H, J = 7.2 Hz, −CH2Me), 1.22 (d, J = 8.4 Hz,
1H, CH), 1.30 (m, 1H, −CHH), 1.39 (d, J = 7.2 Hz, 1H, CH),
1.48 (m, 1H, −CHH), 1.95- 2.1 (m, 4H, COD), 2.15−2.3 (m, 2H,
COD), 2.4−2.55 (m, 2H, COD), 3.0−3.1 (m, 1H, COD), 3.3−3.45
(m, 2H, COD), 3.49 (s, 3H, −OMe), 4.52−4.57 (m, 1H, COD), 4.86
(dd, J = 8.1, 4.5 Hz, 1H, CH), 6.10 (dd, J = 7.2, 4.8 Hz, 1H, CH).
IR (KBr, cm−1): 1685 (νCO), 2277 (νNCMe), 1586, 1570 (νCC).
Anal. Calcd for C18H27NO2Ru: C, 55.37; H, 6.97; N, 3.59. Found: C,
55.46; H, 7.16; N, 2.74. The PPh3 analogue 3aaPPh3 was prepared as
follows: complex 3aa (127.3 mg, 0.418 mmol) was treated with methyl
acrylate (38.0 μL, 0.420 mmol) in benzene for 6 h as described above,
and then PPh3 (109.7 mg, 0.418 mmol) was added into the solution
and the reaction mixture was stirred at room temprature for 3 h. After
removal of all volatile materials, the resulting yellow powder was
recrystallized from cold Et2O to give yellow but slightly black block
crystals of Ru[methyl η4-cisoid-(2E,4E)-hepta-2,4-dienoate](η4-1,5-
CONCLUDING REMARKS
■
In summary, the reactions reported here provide chemo-
selective cross dimerization between conjugated dienes and
electron-deficient alkenes. The formal 6e coordination sites at
Ru(0) favor the conjugated diene (4e) and electron-deficient
alkene (2e), while the highly Lewis basic Ru(0) center facilitates
the oxidative coupling reaction between them. The C−C bond-
forming step can be regarded as the nucleophilic attack of the
coordinated diene fragment to the coordinating alkene, and
C−C bond formation prefers the sterically congested side of
the 1,3-dienes having an alkyl group owing to the induction
effect. The overall mechanism toward the coupling reaction is
1
COD)(PPh3) (3aaPPh3) in 36% yield (92.3 mg, 0.150 mmol). H
NMR (300 MHz, C6D6, rt): δ −0.59 (m, 1H, CH), 0.36 (t, J =
7.5 Hz, 1H, CH), 0.69 (t, J = 7.2 Hz, 1H, −CH2Me), 0.75−0.82 (m,
1H, COD), 0.92−1.02 (m, 1H, −CHH), 1.20−1.27 (m, 1H, −CHH),
1.38−1.65 (m, 1H, COD), 1.66−2.42 (m, 7H, COD), 3.44 (s,
3H, −OMe), 3.17−3.20 (m, 1H, COD), 3.81−3.90 (m, 1H, COD),
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4.70−4.77 (m, 1H, COD), 4.91 (t, J = 7.5 Hz, 1H, CH), 6.27 (t, J =
7.5 Hz, 1H, CH), 6.89−7.08 (m, 9H, PPh3), 7.69−7.80 (m, 6H,
PPh3). 31P{1H} NMR (122 MHz, C6D6): δ 51.84 (s). IR (KBr, cm−1):
1691 (νCO), 1586, 1570 (νCC). Anal. Calcd for C34H39O2PRu: C,
66.76; H, 6.43. Found: C, 66.64; H, 6.52. The CO analogue 3aaCO
was prepared as follows: similar to 3aaPPh3, complex 3aa was pre-
pared in situ by the reaction of 2a (94 mg, 0.31 mmol) with methyl
acrylate (27.8 μL, 0.309 mmol). Then, excess CO (0.1 MPa) was
introduced into the solution and the system was stirred for 3 h under
CO atmosphere. After removal of all volatile materials, a yellow
powder was obtained, which was recrystallized from cold Et2O to give
yellow needles of Ru[methyl η4-cisoid-(2E,4E)-hepta-2,4-dienoate]-
(η4-1,5-COD)(CO) (3aaCO) in 53% yield (62.3 mg, 0.165 mmol).
1H NMR (300 MHz, C6D6, rt): δ 0.77 (m, 1H, CH), 0.78 (t, J =
7.2 Hz, 1H, −CH2Me), 1.01 (m, 1H, −CHH), 1.12 (d, J = 6.9 Hz, 1H,
CH), 1.60−1.73 (m, 2H, COD), 1.88−2.01 (m, 4H, COD), 3.31 (s,
3H, −OMe), 3.08−3.10 (m, 2H, COD), 3.41 (m, 1H, −CHH), 3.43−
3.48 (m, 1H, COD), 4.46−4.49 (m, 1H, COD), 4.64 (t, J = 5.7 Hz,
1H, CH), 5.94 (dd, J = 6.9, 5.7 Hz, 1H, CH). IR (KBr, cm−1):
1739 (νRuCO), 1699 (νCO), 1588, 1541 (νCC). Heating of 3aaPPh3
at 70 °C in benzene-d6 produced Ru(methyl anti,anti-η3-hept-4-
enoate-3-yl)(η5-cyclohexa-2,4-diene-1-yl) (6) in quantitative yield.
With N,N-Dimethylacrylamide. Into an NMR tube containing 2a
(7.2 mg, 0.029 mmol) and benzene-d6 (600 μL), N,N-dimethylacry-
lamide (2.5 μL, 0.029 mmol) was added under an ice bath for 10 min
and then at room temperature for 4 h to give Ru[η4-cisoid-(2E,4E)-
N,N-dimethylhepta-2,4-dienylamide](η4-1,5-COD)(NCMe) (3ae) in
96% yield. 1H NMR (400 MHz, C6D6, rt): δ 0.61 (s, 3H, NCMe), 0.93
(s, 6H, −NMe2), 1.04 (t, J = 7.3 Hz, 1H, 7-Me), 1.15−1.20 (m, 1H, 5-
CH), 1.25 (d, J = 6.9 Hz, 1H, 2-CH), 1.29−1.40 (m, 1H, 6-CHH),
1.47−1.56 (m, 1H, 6-CHH), 1.89−3.03 (m, 8H, COD), 3.18−3.23
(m, 2H, COD), 3.42−3.47 (m, 1H, COD), 4.55−4.60 (m, 1H, COD),
4.92 (dd, J = 13.8, 5.5 Hz, 1H, 4-CH), 6.43 (dd, J = 6.9, 5.5 Hz, 1H,
3-CH). The PPh3 anaglogue 3aePPh3 was prepared as follows: com-
plex 2a (109.5 mg, 0.360 mmol) was dissolved in benzene (6 mL) and
N,N-dimethylacrylamide (37.0 μL, 0.360 mmol) was added. The
reaction mixture was stirred under an ice bath for 3 h and then at room
temperature for an additional 3 h. Then, PPh3 (94.4 mg, 0.360 mmol)
was added into the solution and the mixture was stirred for 3 h. After
removal of all volatile materials, a yellow powder was obtained, which
was recrystallized from cold Et2O to give yellow block crystals of
Ru[η4-cisoid-(2E,4E)-N,N-dimethylhepta-2,4-dienylamide](η4-1,5-
COD)(PPh3) (3aePPh3) in 32% yield (73 mg, 0.117 mmol). 1H
NMR (300 MHz, C6D6, rt): δ −0.45 (q, J = 10.8 Hz, 1H, 5-CH),
0.47−0.52 (m, 1H, 2-CH), 0.58 (m, 1H, COD), 0.72 (dt, J = 7.3, 2.8
Hz, 1H, 7-Me), 0.73−0.84 (m, 1H, COD), 0.98−1.20 (m, 2H, 6-CH2),
1.38−1.41 (m, 1H, COD), 1.75−1.95 (m, 3H, COD), 2.09 (m, 1H,
COD), 2.18 (s, 3H, −NMe2), 2.27−2.29 (m, 1H, COD), 2.46−2.53
(m, 1H, COD), 2.81 (s, 3H, −NMe2), 3.23−3.27 (m, 1H, COD),
3.76−3.83 (m, 1H, COD), 5.04 (m, 1H, 4-CH), 5.59 (m, 1H, COD),
6.50 (m, 1H, 3-CH), 7.03 (m, 9H, PPh3), 7.64−7.68 (m, 6H, PPh3).
IR (KBr, cm−1): 1608 (νCO). Anal. Calcd for C35H42NOPRu: C,
67.12; H, 6.96. Found: C, 67.29; H, 6.78.
1
6: H NMR (300 MHz, C6D6): δ 0.08−0.21 (m, 1H, CH2 in cyclo-
octadienyl), 0.45−0.55 (m, 1H, CH2 in cyclooctadienyl), 0.68−0.71
(m, 2H, CH2 in cyclooctadienyl), 0.78 (t, J = 7.2 Hz, 3H, 7-Me), 1.16−
1.23 (overlapped, 2H, 6-CH2 and 5-CH), 1.34−1.43 (overlapped, 1H,
6-CHH), 1.42−1.51 (overlapped, 1H, CH2 in cyclooctadienyl), 1.56
(br, 1H, CH2 in cyclooctadienyl), 1.61−1.67 (m, 1H, 2-CH2), 1.77
(t, J = 9.0 Hz, 1H, 3-CH), 3.17 (br, 1H, CH in cyclooctadienyl),
3.41−3.44 (m, 1H, 2-CH2), 3.44−3.55 (m, 1H, CH in cyclo-
octadienyl), 3.62 (s, 3H, −OMe), 3.89 (br, 1H, CH in cyclo-
octadienyl), 3.92−3.97 (m, 1H, CH in cyclooctadienyl), 4.72 (t, J =
9.0 Hz, 1H, 4-CH), 5.60 (t, J = 6.0 Hz, 1H, CH in cyclooctadiehyl),
6.98−7.21 (m, 9H, meta- and para-PPh3), 7.62−7.81 (m, 6H, ortho-
PPh3). 31P{1H} (122 MHz, C6D6): δ 57.31 (s).
With Vinyl Acetate. Complex 2a (8.0 mg, 0.026 mmol) in benzene-
d6 (600 μL) reacted with vinyl acetate (2.4 μL, 0.026 mmol) at room
temperature immediately to give Ru[(η3-CH2CHCH)CH2CH2{CH-
(OC(O)Me-η1C,κ1O)}](η4-1,5-COD)(NCMe) (3af) in 68% yield. 1H
3
NMR (400 MHz, C6D6, rt): δ 0.69 (td, J = 8.7, 4.1 Hz, 1H, CeH),
With 3-Buten-2-on. Similar to the reaction of 2a with methyl
acrylate, 2a (5.1 mg, 0.017 mmol) was treated with 3-buten-2-one
(2.4 μL, 0.017 mmol) in benzene-d6 (600 μL) under an ice bath for
10 min and then at room temperature for 24 h to give Ru[η4-cisoid-
(3E,5E)-octa-3,5-dien-2-one](η4-1,5-COD)(NCMe) (3ab) in 92%
1.34 (s, 3H, OC(O)Me), 1.4 (m, 1H, C3H2), 1.7 (m, 1H, CcH2), 2.2
(m, 1H, C3H), 2.2 (m, 1H, CcH2), 2.28 (br m, 1H, CfH), 2.36 (td, 3J =
10.5, 4.1 Hz, 1H, syn-C4H), 2.56 (td, 3J = 8.7, 4.1 Hz, 1H, CaH2), 2.75
(m, 2H, CdH2 and CgH2), 2.80 (d, 3J = 12.8 Hz, 1H, anti-C6H2), 3.07
(dddd, J = 11.4, 10.4, 8.7, 6.2 Hz, 1H, CdH2), 3.28 (tdd, 2J = 3J = 17.4
Hz, 3J = 5.4, 2.3 Hz, 1H, C2H2), 3.36 (br dm, 2J = 17 Hz, 1H, C2H2),
1
yield. H NMR (300 MHz, C6D6, rt): δ 0.89 (s, 3H, NCMe), 1.02
(t, J = 7.2 Hz, 1H, CH2Me), 1.30−1.24 (m, 1H, CHH), 1.47 (d, J =
7.5 Hz, 1H, CH), 1.52−1.40 (m, 1H, CHH), 1.57−2.50 (m, 8H,
COD), 1.87 (s, 3H, −OMe), 2.98−3.04 (m, 1H, COD), 3.15−3.34
(m, 2H, COD), 4.39−4.46 (m, 1H, COD), 4.81 (dd, J = 8.0, 5.3 Hz,
1H, CH), 6.15 (dd, J = 7.5, 5.3 Hz, 1H, CH). Anal. Calcd for
C18H27NORu: C, 57.73; H, 7.27; N, 3.74. Found: C, 57.48; H, 7.04;
N, 2.46.
3
3
3.64 (br t, J = 7 Hz, 1H, CbH), 3.89 (d, J = 8.7 Hz, 1H, syn-C6H2),
3
4.46 (ddd, J = 12.8, 10.5, 8.7 Hz, 1H, C5H), 7.86 (br s, 1H, C1H).
13C{1H} NMR (100 MHz, C6D6, rt): δ 17.8 (s, OC(O)Me), 28.3
(s, Ch), 30.8 (s, Cc), 33.5(or 33.6) (s, C3), 33.6(or 33.5) (s, Cd), 36.1
(s, Cg), 43.5 (s, C6), 56.4 (s, C2), 65.9 (s, Cb), 70.5(or 70.6) (s, Ce),
70.6(or 70.5) (s, Cf), 73.4 (s, Ca), 93.1 (s, C4), 119.9 (s, C5), 124.8
(s, C1), 179.9 (s, OC(O)Me).
With tert-Butyl Acrylate. Similar to the reaction with methyl acryl-
ate, the reaction of 2a (6.6 mg, 0.022 mmol) with tert-butyl acrylate
(1.9 μL, 0.022 mmol) produced Ru[tert-butyl η4-cisoid-(2E,4E)-hepta-
2,4-dienoate](η4-1,5-COD)(NCMe) (3ac) in 53% yield. 1H NMR
(300 MHz, C6D6, rt): δ 0.88 (s, 3H, −NCMe), 1.01 (t, J = 7.8 Hz, 1H,
−CH2Me), 1.16 (m, 1H, CH), 1.32 (d, J = 7.8 Hz, 1H, CH), 1.
38 (m, 1H, −CHH), 1.44 (m, 1H, −CHH), 1.48 (s, 3H, −OMe), 1.9−
2.6 (m, 8H, COD), 3.0−3.1 (m, 1H, COD), 3.3−3.5 (m, 2H, COD),
4.59 (m, 1H, COD), 4.85 (dd, J = 4.8, 8.4 Hz, 1H, CH), 6.07 (dd,
J = 4.8, 7.8 Hz, 1H, CH).
Reactions of Ru(η4-cisoid-isoprene)(η4-1,5-COD)(NCMe) (2b)
with Conjugated Carbonyls. With Methyl Acrylate. Similar to 2a,
treatment of 2b (12.8 mg, 0.040 mmol) with methyl acrylate (3.6 μL,
0.040 mmol) produced Ru[methyl η4-cisoid-(2E,4E)-6-methylhepta-
2,4-dienoate](η4-1,5-COD)(NCMe) (3ba) in 54% yield. 1H NMR
(400 MHz, C6D6, rt): δ 0.85 (s, 3H, NCMe), 0.90 (d, J = 6.9 Hz, 3H,
7-Me), 1.04 (t, J = 8.4 Hz, 1H, 5-CH), 1.12 (d, J = 6.9 Hz, 3H, 7-Me),
1.37 (d, J = 7.8 Hz, 1H, 2-CH), 1.33−1.40 (m, 1H, 6-CH), 1.90−2.25
(m, 4H, COD), 2.29−2.56 (m, 3H, COD), 2.61−2.71 (m, 1H, COD),
3.10−3.15 (m, 1H, COD), 3.30−3.34 (m, 1H, COD), 3.40−3.43 (m,
1H, COD), 3.40−3.43 (m, 1H, COD), 3.45 (s, 3H, −OMe), 4.55−
4.60 (m, 1H, COD), 4.85 (dd, J = 8.4, 5.3 Hz, 1H, 4-CH), 6.07 (dd,
J = 7.8, 5.3 Hz, 1H, 5-CH).
With Methyl (E)-2-Butenoate. Complex 2a (8.6 mg, 0.028 mmol)
in benzene-d6 (600 μL) reacted with methyl (E)-crotonate (5.8 μL,
0.056 mmol) under an ice bath for 10 min and then at room
temperature for 4 h to give Ru[methyl cisoid-η4-(2E,4E)-3-methyl-
hepta-2,4-dienoate](η4-1,5-COD)(NCMe) (3ad) in 41% yield. 1H
NMR (400 MHz, C6D6, rt): δ 0.86 (s, 3H, NCMe), 1.05 (t, J = 7.3 Hz,
3H, 7-Me), 1.07 (s, 1H, 2-CH), 1.22 (dt, J = 7.4, 14.2 Hz, 1H, 5-CH),
1.33 (dquintet, J = 14.2, 7.4 Hz, 1H, 6-CH2), 1.44 (dquintet, J = 14.2
7.4 Hz, 1H, 6-CH2), 1.9−2.1 (m, 3H, COD), 2.2−2.3 (m, 2H, COD),
2.4−2.5 (m, 2H, COD), 2.6 (m, 1H, COD), 2.65 (s, 3H, 3-Me), 2.9
(m, 1H, COD), 3.2−3.3 (m, 2H, COD), 3.46 (s, 3H, −OMe), 4.0−4.1
(m, 1H, COD), 4.66 (d, J = 8.2 Hz, 1H, 4-CH).
With 3-Buten-2-one. Similar to 2a, treatment of 2b (10.9 mg,
0.034 mmol) with 3-buten-2-one (2.9 μL, 0.035 mmol) gave Ru[η4-
cisoid-(3E,5E)-7-methylocta-3,5-dien-2-one](η4-1,5-COD)(NCMe)
1
(3bb) in 59% yield. H NMR (400 MHz, C6D6, rt): δ 0.90 (s, 3H,
NCMe), 0.92 (d, J = 6.4 Hz, 3H, 7-Me), 1.07 (t, J = 8.4 Hz, 1H,
5-CH), 1.14 (d, J = 6.4 Hz, 3H, 7-Me), 1.25−1.37 (m, 1H, 6-CH), 1.43
(d, J = 7.5 Hz, 1H, 2-CH), 1.62−1.65 (m, 1H, COD), 1.89 (s, 3H,
−COMe), 1.97−2.05 (m, 2H, COD), 2.16−2.25 (m, 2H, COD),
4015
dx.doi.org/10.1021/om300234d | Organometallics 2012, 31, 4006−4019

Organometallics
Article
2.39−2.56 (m, 2H, COD), 3.06−3.11 (m, 1H, COD), 3.15−3.19 (m,
1H, COD), 3.26−3.29 (m, 1H, COD), 4.42−4.47 (m, 1H, COD),
4.81 (dd, J = 8.6, 5.3 Hz, 1H, 4-CH), 6.12 (dd, J = 7.5, 5.3 Hz, 1H, 5-
CH). Anal. Calcd for C19H29NORu: C, 58.74; H, 7.52; N, 3.61.
Found: 53.93; H, 7.15; N, 2.83.
With N,N-Acrylamide. Treatment of 2b (7.1 mg, 0.022 mmol) with
N,N-dimethylacrylamide (2.3 μL, 0.023 mmol) gave Ru[η4-cisoid-
(2E,4E)-N,N,6-trimethyl-2,4-heptadienylamide](η4-1,5-COD)-
(NCMe) (3be) in 46%. 1H NMR (400 MHz, C6D6, rt): δ 0.90 (s, 3H,
NCMe), 0.92 (d, J = 6.4 Hz, 3H, 7-Me), 1.07 (t, J = 8.4 Hz, 1H, 5-
CH), 1.14 (d, J = 6.4 Hz, 3H, 7-Me), 1.25−1.37 (m, 1H, 6-CH), 1.43
(d, J = 7.5 Hz, 1H, 2-CH), 1.62−1.65 (m, 1H, COD), 1.89 (s, 3H,
−COMe), 1.97−2.05 (m, 2H, COD), 2.16−2.25 (m, 2H, COD),
2.39−2.56 (m, 2H, COD), 3.06−3.11 (m, 1H, COD), 3.15−3.19 (m,
1H, COD), 3.26−3.29 (m, 1H, COD), 4.42−4.47 (m, 1H, COD),
4.81 (dd, J = 8.6, 5.3 Hz, 1H, 4-CH), 6.12 (dd, J = 7.5, 5.3 Hz, 1H,
5-CH).
1.95−2.04 (m, 3H, COD), 2.21−2.30 (m, 2H, COD), 2.46−2.71 (m,
3H, COD), 3.16−3.21 (m, 1H, COD), 3.29−3.41 (m, 2H, COD),
3.50 (s, 3H, −OMe), 4.43−4.47 (m, 1H, COD), 5.88 (d, J = 7.1 Hz,
1H, 3-CH). Minor: δ 0.83 (s, 3H, NCMe), 0.92 (t, J = 6.9 Hz, 3H,
8-Me), 1.03 (t, J = 7.4 Hz, 1H, 5-CH), 1.20 (m, 1H, 5-CH), 1.38 (d,
J = 7.8 Hz, 1H, 2-CH), 1.81−2.87 (overlapped, 8H, COD), 1.95−1.97
(overlapped, 2H, 7-CH2), 2.22−2.24 (overlapped, 2H, 6-CH2), 3.01−
3.06 (m, 1H, COD), 3.48 (s, 3H, −OMe), 3.59−3.63 (m, 1H, COD),
4.24−4.27 (m, 1H, COD), 4.49−4.53 (m, 1H, COD), 4.85−4.89 (m,
1H, 4-CH), 6.08−6.11 (m, 1H, 3-CH). Anal. as a mixture of isomers:
Calcd for C19H29NO2Ru: C, 56.41; H, 7.23; N, 3.46. Found: 56.00;
6.64; N, 2.44.
With 3-Buten-2-one. Treatment of 2d (15.8 mg, 0.050 mmol) with
3-buten-2-one (4.2 μL, 0.050 mmol) gave a mixture of Ru[η4-cisoid-
(3E,5E)-5-methylocta-3,5-dien-2-one](η4-1,5-COD)(NCMe) (3db-b)
(41%) and Ru[η4-cisoid-(3E,5E)-nona-3,5-dien-2-one](η4-1,5-COD)-
1
(NCMe) (3db-l) (21%). 3db-b: H NMR (400 MHz, C6D6, rt): δ
Reactions of Ru(η4-cisoid-2,3-dimethyl-1,3-butadiene)(η4-
1,5-COD)(NCMe) (2c) with Conjugated Carbonyls. With Methyl
Acrylate. Complex 2c (106.1 mg, 0.320 mmol) in benzene (5 mL)
was treated with methyl acrylate (28.8 μL, 0.320 mmol) under an ice
bath for 3 h and then at room temperature for 3 h. After removal of
all volatile materials, a yellow powder was obtained, which was re-
crystallized from cold Et2O to give yellow block crystals of Ru[methyl
η4-cisoid-(6E)-5,6-dimethylhepta-4,6-dienoate](η4-1,5-COD)(NCMe)
0.90 (s, 3H, NCMe), 0.98 (t, J = 6.9 Hz, 3H, 7-Me), 1.07 (t, J = 6.9 Hz,
1H, 5-CH), 1.15 (dqui, J = 13.8, 6.9 Hz, 1H, 6-CHH), 1.43 (d, J = 7.4
Hz, 1H, 2-CH), 1.44−1.56 (m, 1H, 6-CHH), 1.89 (s, 3H, 4-Me), 1.93
(s, 3H, −COMe), 1.70−2.58 (m, 9H, COD), 3.12−3.15 (m, 2H,
COD), 4.30−4.34 (m, 1H, COD), 5.95 (d, J = 7.4 Hz, 1H, 3-CH).
Minor: δ 0.87 (s, 3H, NCMe), 0.94 (t, J = 7.4 Hz, 3H, 9-Me), 1.08−
1.11 (overlapped, 1H, 7-CHH), 1.31−1.34 (m, 1H, 6-CH), 1.38−1.44
(overlapped, 2H, 8-CH2), 1.47 (d, J = 6.4 Hz, 1H, 5-CH), 1.89 (s, 3H,
−COMe), 1.91−2.58 (overlapped, 7H, COD), 2.76−2.81 (m, 1H,
COD), 2.98−3.02 (m, 1H, COD), 3.15−3.19 (overlapped, 1H,
COD), 3.32−3.36 (m, 1H, COD), 4.40−4.43 (m, 1H, COD), 4.83 (t,
J = 6.4 Hz, 1H, 5-CH), 6.15 (t, J = 6.4 Hz, 1H, 4-CH).
1
(3ca) in 32% yield (50.6 mg, 0.102 mmol). H NMR (400 MHz,
C6D6, rt): δ 0.29 (s, 1H, 7-endo-CH), 0.60 (dd, J = 8.0, 5.1 Hz, 1H,
3-CH), 0.99 (s, 3H, −NCMe), 1.59 (s, 1H, 7-exo-CH), 1.65 (dq, J =
14.7, 8.0 Hz, 1H, 3-CH2), 1.84 (s, 3H, 5- or 6-Me), 2.00 (s, 3H, 6- or
5-Me), 2.02−2.11 (m, 1H, −CH2), 1.91−2.18 (m, 4H, COD), 2.39 (t,
J = 8.0 Hz, 2H, 2-CH2), 2.43−2.49 (m, 2H, COD), 2.65−2.87 (m, 3H,
COD), 3.17−3.21 (m, 1H, COD), 3.31 (s, 3H, −OMe), 3.68−3.93
(m, 1H, COD). Anal. Calcd for C20H31NO2Ru: C, 57.39; H, 7.47; N,
3.35. Found: 57.05; H, 7.32; N, 3.16.
With 3-Buten-2-on. Complex 2c (15.4 mg, 0.046 mmol) in
benzene-d6 (600 μL) reacted with 3-buten-2-one (3.9 μL, 0.046
mmol) under an ice bath for 10 min and then at room temperature for
4 h to give Ru{η4-cisoid-(5E)-6,7-dimethylocta-5,7-dien-2-one}(η4-1,5-
COD)(NCMe) (3cb) in 58% yield. 1H NMR (400 MHz, C6D6, rt): δ
0.52 (s, 1H, 8-endo-CH), 0.69 (s, 3H, NCMe), 1.60 (s, 3H, 6-CMe),
1.62 (m, 2H, 4-CH2), 1.65 (m, 1H, 5-endo-CH), 1.71 (m, 1H, 8-exo-
CH), 1.73−1.77 (m, 1H, COD), 1.81−1.88 (m, 2H, COD), 1.93 (t,
J = 8.6 Hz, 2H, 3-CH2), 1.95−2.00 (m, 3H, COD), 2.02 (s, 3H, 7-
CMe), 2.02 (s, 3H, −COMe), 2.14−2.20 (m, 1H, COD), 2.23−2.29
(m, 1H, COD), 2.47−2.53 (m, 1H, COD), 2.68−2.71 (m, 1H, COD),
2.76−2.80 (m, 1H, COD), 3.68−3.72 (m, 1H, COD).
With N,N-Dimethylacrylamide. Treatment of 2d (16.1 mg, 0.051
mmol) with N,N-dimethylacrylamide (5.2 μL, 0.051 mmol) gave
Ru[η4-cisoid-(2E,4E)-N,N,4-trimethylhepta-2,4-dieylamide](η4-1,5-
COD)(NCMe) (3de-b) (60%) and Ru[η4-cisoid-(2E,4E)-N,N-dime-
thylocta-2,4-dienylamide](η4-1,5-COD)(NCMe) (3de-l) (4%). 3de-b:
1H NMR (400 MHz, C6D6, rt): δ 0.95 (s, 3H, NCMe), 0.99 (t, J = 7.3
Hz, 3H, 7-Me), 1.20 (t, J = 7.3 Hz, 1H, 5-CH), 1.21 (d, J = 6.9 Hz, 1H,
2-CH), 1.18−1.27 (m, 1H, 6-CHH), 1.55 (dqui, J = 14.6, 7.3 Hz, 1H,
6-CHH), 1.96 (s, 3H, 4-Me), 1.96 (s, 3H, -NMe2), 1.97−2.23 (m, 3H,
COD), 2.27 (s, 3H, −NMe2), 2.41−3.04 (m, 6H, COD), 3.10−3.15
(m, 2H, COD), 4.45−4.50 (m, 1H, COD), 6.22 (d, J = 6.9 Hz, 1H,
3-CH). The resonances of the minor isomer were almost overlapped
with the major isomer. Because of the general treand of these reac-
1
tions, we tentatively assigned it as the linear isomer. H NMR (400
MHz, C6D6, rt): δ 4.56 (m, 1H, COD), 4.82 (m, 1H, 4-CH), 6.22 (m,
1H, 3-CH). Anal. as a mixture of isomers: Calcd for C20H32N2ORu: C,
57.53; H, 7.72; N, 6.71. Found: C, 57.22; H, 7.78; N, 5.87.
Reaction of Ru[η4-cisoid-(E)-2,5-dimethylhexa-1,3-diene](η4-
1,5-COD)(NCMe) (2e) with Methyl Acrylate. Treatment of 2e (9.8
mg, 0.027 mmol) with methyl acrylate (2.5 μL, 0.029 mmol) gave
Ru[methyl η4-cisoid-(2E,4E)-4-isopropyl-6-methylhepta-2,4-dienoate]-
(η4-1,5-COD)(NCMe) (3ea) in 87% yield. 1H NMR (400 MHz,
C6D6, rt): δ 0.74 (d, J = 9.2 Hz, 1H, 5-CH), 0.89 (s, 3H, NCMe), 0.95
(t, J = 7.4 Hz, 3H, 7-Me), 1.05 (s, 3H, 6 or 7-Me), 1.11 (s, 3H, 6 or
7-Me), 1.20 (s, 3H, 4-CHMe), 1.30 (d, J = 7.6 Hz, 1H, 2-CH), 1.35−
1.42 (m, 1H, 6-CHMe), 1.45 (s, 3H, 4-CHMe), 1.82−1.87 (m, 1H,
COD), 1.95−2.09 (m, 1H, COD), 2.26 (septet, J = 6.6 Hz, 1H, 4-
CHMe), 2.35−2.52 (m, 3H, COD), 2.60−2.74 (m, 2H, COD), 3.03−
3.08 (m, 1H, COD), 3.13−3.17 (m, 1H, COD), 3.39−3.44 (m, 1H,
COD), 3.50 (s, 3H, −OMe), 4.43−4.47 (m, 1H, COD), 6.08 (d, J =
7.6 Hz, 1H, 3-CH). Anal. Calcd for C22H35NO2Ru, C, 59.17; H, 7.90;
N, 3.14. Found: C, 59.30; H, 8.03; N, 3.14.
Catalytic Reactions between Conjugated Dienes and
Conjugated Carbonyls. As a typical example, the reaction of 1,3-
butadiene with methyl acrylate was described. The product yields were
estimated from the GLC analysis with an internal standard method
(dibenzyl as a standard). The minor species, which could not be
characterized by NMR spectrum, were determined by GLC and GC-
MS by assuming the same relative sense as the major species in GLC.
1,3-Butadiene with Methyl Acrylate. In a Schlenk tube, 2a
(30.0 mg, 0.10 mmol) was dissolved in benzene (2 mL), and then
With N,N-Dimethylacrylamide. Complex 2c (10.2 mg, 0.031
mmol) in benzene-d6 reacted with N,N-dimethylacrylamide (3.2 μL,
0.030 mmol) under an ice bath for 10 min and then at room tem-
perature for 4 h to give Ru[η4-cisoid-(2E,4E)-N,N-dimethylhepta-2,4-
dienylamide](η4-1,5-COD)(NCMe) (3ce) in 84% yield. 1H NMR
(400 MHz, C6D6, rt): δ 0.53 (s, 1H, 7-endo-CH), 0.75 (s, 3H,
−NCMe), 0.84−0.88 (m, 1H, 3-CH), 1.71 (s, 1H, 7-exo-CH), 1.88−
1.90 (m, 1H, 3-CH2), 1.92−1.93 (m, 1H, 4-endo-CH), 2.02 (s, 3H,
−NMe2), 2.02 (s, 3H, 5-CMe), 2.04 (s, 3H, 6-CMe), 2.02−2.05 (m,
2H, COD), 2.11−2.18 (m, 3H, COD), 2.47−2.53 (m, 2H, COD),
2.65 (s, 3H, NMe2), 2.67−2.70 (m, 2H, COD), 2.76−2.79 (m, 1H,
COD), 2.93−2.98 (m, 1H, COD), 3.93 (m, 1H, COD). Anal. Calcd
for C21H34N2ORu: C, 58.44; H, 7.94; N, 6.49. Found: 58.77; H, 7.93;
N, 5.39.
Reaction of Ru[η4-cisoid-(E)-1,3-pentadiene](η4-1,5-COD)-
(NCMe) (2d) with Conjugated Carbonyls. With Methyl Acrylate.
Treatment of 2d (13.3 mg, 0.042 mmol) with methyl acrylate
(3.8 μL, 0.042 mmol) gave a mixture of Ru[methyl η4-cisoid-(2E,4E)-
4-methylhepta-2,4-dienoate](η4-1,5-COD)(NCMe) (3da-b) (65%)
and Ru[methyl η4-cisoid-(2E,4E)-octa-2,4-dienoate](η4-1,5-COD)-
1
(NCMe) (3da-l) (19%). 3da-b: H NMR (400 MHz, C6D6, rt): δ
0.85 (s, 3H, NCMe), 0.95 (t, J = 7.4 Hz, 3H, 7-Me), 1.03 (t, J = 7.4 Hz,
1H, 5-CH), 1.18 (dqui, J = 14.8, 7.4 Hz, 1H, 6-CHH), 1.35 (d, J = 7.1 Hz,
1H, 2-CH), 1.50 (dqui, J = 14.8, 7.4 Hz, 1H, 6-CHH), 1.89 (s, 3H, 4-Me),
4016
dx.doi.org/10.1021/om300234d | Organometallics 2012, 31, 4006−4019

Organometallics
Article
methyl acrylate (480 μL, 5.0 mmol) was introduced by a hypodermic
syringe. The solution was moved to a stainless steel autoclave (50 mL
volume) by a cannular tube. 1,3-Butadiene (113 mL, 5.0 mmol) was
introduced into the autoclave, and the reaction vessel was heated at
70 °C for 4 h. After the reaction, the solution was moved to an
Erlenmeyer flask, and all volatile materials were removed by a rotary
(400 MHz, C6D6, rt): δ 1.51 (s, 3H, 7 or 8-Me), 1.61 (s, 3H, 7 or 8-
Me), 1.85 (s, 3H, −COMe), 2.79 (d, J = 7.3 Hz, 2H, 3-CH2), 5.59 (dt,
J = 15.2, 7.3 Hz, 1H, 4-CH), 5.81 (d, J = 11.0 Hz, 1H, 6-CH), 6.21
(dd, J = 15.2, 11.0 Hz, 1H, 5-CH). GLC: retetntion time (min) = 19.69.
(E)-1,3-Pentadiene with Methyl Acrylate. Methyl (2E,5Z)-4-
methyl-2,5-heptadienoate. Yield: 41%. 1H NMR (400 MHz, C6D6, rt):
δ 0.84 (d, J = 6.9 Hz, 3H, 4-Me), 1.35 (dd, J = 6.9, 1.8 Hz, 3H, 7-Me),
3.01 (sextet, J = 6.9 Hz, 1H, 4-CH), 3.45 (s, 3H, −OMe), 5.05 (dt, J =
10.0, 1.8 Hz, 1H, 5-CH), 5.33 (dq, J = 10.0, 6.9 Hz, 1H, 6-CH), 5.86
(d, J = 15.6 Hz, 1H, 2-CH), 6.99 (dd, J = 15.6, 6.9 Hz, 1H, 3-CH).
GLC: retention time (min) = 18.24. Minor species: retetntion time
(min) = 16.93, 20.11, 21.54.
1
evaporator. The product was confirmed by H NMR, GLC, and GC-
1
MS. (2E,5Z)-MHD: H NMR (CDCl3, 300 MHz): δ 1.60 (d, J = 7.5
Hz, 3H, 7-Me), 2.93 (t, J = 6.3 Hz, 2H, 4-CH2), 3.70 (s, 3H, −OMe),
5.38 (dtq, J = 13.8, 6.9, 1.5 Hz, 1H, 5-CH), 5.61 (dqt, J = 14.4, 5.4,
1.5 Hz, 1H, 6-CH), 5.82 (dt, J = 15.6, 1.8 Hz, 1H, 2-CH), 6.94 (dt, J =
15.6, 6.2 Hz, 1H, 3-CH). GLC: retention time (min) = 17.33. MS (m/
e): 140 (M+), 111, 109, 81. Lit.14 1H NMR (CDCl3, 360 MHz): δ 1.63
(d, J = 6.7 Hz, 3H), 2.95 (dd, J = 6.6, 6.4 Hz, 2H), 3.73 (s, 3H), 5.35−
5.48 (m, 1H), 5.55−5.71 (m, 2H), 5.84 (dt, J = 15.7, 1.7 Hz, 1H), 6.96
(dt, J = 15.7, 6.3 Hz, 1H). Minor species: retention time (min) =
14.20, 16.12.
(Z)-1,3-Pentadiene with Methyl Acrylate. Methyl (2E,5Z)-4-
methyl-2,5-heptadienoate. Yield: 23%.
(E)-1,3-Pentadiene with 3-Buten-2-one. (3E,6Z)-5-Methylocta-
3,6-dien-2-one. Yield: 16%. 1H NMR (400 MHz, C6D6, rt): δ 0.85 (d,
J = 6.9 Hz, 3H, 5-Me), 1.38 (d, J = 6.9 Hz, 3H, 8-Me), 1.84 (s, 3H, 1-
COMe), 3.01 (m, 1H, 5-CH), 5.06 (m, 1H, 6-CH), 5.35 (dq, J = 11.0,
6.9 Hz, 1H, 7-CH), 5.95 (d, J = 16.0 Hz, 1H, 3-CH), 6.44 (dd, J =
16.0, 6.4 Hz, 1H, 4-CH). GLC: retention time (min) = 18.16. Minor
species: retention time (min) = 18.85, 20.34, 21.16.
(E)-1,3-Pentadiene with N,N-Dimethylacrylamide. (2E,5Z)-
N,N,4-Trimethylhepta-2,5-dienylamide. Yield: 44%. 1H NMR (400
MHz, C6D6, rt): δ 0.97 (d, J = 6.9 Hz, 3H, 4-Me), 1.45 (d, J = 6.9 Hz,
3H, 7-Me), 2.36 (s, 3H, −NMe2), 2.72 (s, 3H, −NMe2), 3.17 (m, 1H,
4-CH), 5.21 (m, 1H, 5-CH), 5.39 (m, 1H, 6-CH), 6.09 (d, J = 15.1 Hz,
1H, 2-CH), 7.10 (m, 1H, 3-CH). GLC: retention time (min) = 31.97.
Minor species: retention time (min) = 26.26, 33.78, 34.62.
1,3-Butadiene with 3-Buten-2-one. 3-Cyclohexenyl-2-ethanone.
1
Yield: 85%. H NMR (400 MHz, C6D6, rt): δ 1.43−1.46 (m, 1H,
1-CH in cyclohexenyl), 1.59−1.66 (m, 2H, 2- and 5-CH of cyclo-
hexenyl), 1.67 (s, 3H, −COMe), 1.73−1.94 (m, 2H, 2- and 5-CH of
cyclohexenyl), 2.08−2.11 (m, 2H, 6-CH2 of cyclohexenyl), 5.56−5.62
(m, 2H, 3- and 4-CH2 of cyclohexenyl). GLC: retention time (min) =
15.81. MS (m/z): 124 (M+).
1,3-Butadiene with N,N-Dimethylacrylamide. (2E,5Z)-N,N-
Dimethylhepta-2,5-dienylamide. Yield: 35%. 1H NMR (400 MHz,
C6D6, rt): δ 1.59 (dd, J = 6.8, 1.2 Hz, 3H, 7-CH3), 2.15 (s, 3H,
−NMe2), 2.62 (s, 3H, −NMe2), 2.83 (d, J = 6.8 Hz, 2H, 2-CH2), 5.34
(dq, J = 10.7, 6.8 Hz, 1H, 6-CH), 5.93 (dt, J = 15.3, 6.8 Hz, 1H, 3-
CH), 6.08 (t, J = 10.7 Hz, 1H, 4-CH), 6.39 (ddq, J = 15.3, 10.7, 1.2
Hz, 1H, 5-CH). GLC: retention time (min) = 32.45. Minor species:
retention time (min) = 31.43, 32.31.
2,4-Hexadiene with Methyl Acrylate. Methyl (2E,5Z)-4-
1
methylocta-2,5-dienoate. Yield: 18%. H NMR (400 MHz, C6D6, rt):
δ 0.80 (t, J = 7.6 Hz, 3H, 8-Me, 0.85 (d, J = 6.9 Hz, 3H, 4-CHMe), 1.81
(m, 2H, 7-CH2), 3.01 (m, 1H, 4-CH), 3.43 (s, 3H, −OMe), 5.01 (dd,
J = 10.6, 9.2 Hz, 2H, 5-CH), 5.32 (dt, J = 10.6, 7.4 Hz, 1H, 6-CH),
5.86 (d, J = 15.6 Hz, 1H, 2-CH), 6.98 (dd, J = 15.6, 6.4 Hz, 1H, 3-
CH). GLC: retention time (min) = 20.17.
2,3-Dimethylbutadiene with Methyl Acrylate. Methyl (3E)-
5,6-dimethyl-3,5-heptadienoate. Yield: 71%. 1H NMR (400 MHz,
C6D6, rt): δ 1.58 (s, 3H, 5, 6, or 7-Me), 1.64 (s, 3H, 5, 6, or 7-CH3),
1.70 (s, 3H, 5, 6, or 7-CH3), 2.99 (d, J = 7.5 Hz, 2H, 2-CH2), 3.32
(s, 3H, −OMe), 5.74 (dt, J = 15.4, 7.5 Hz, 1H, 3-CH), 6.58 (d, J =
15.4 Hz, 1H, 4-CH). GC: retention time (min) = 24.58. Methyl (2E)-
5,6-dimethyl-2,5-heptadienoate. Yield: 26%. 1H NMR (400 MHz,
C6D6, rt): δ 1.43 (s, 3H, 5, 6, or 7-CH3), 1.44 (s, 3H, 5, 6, or 7-CH3),
1.48 (s, 3H, 5, 6, or 7-CH3), 2.57 (d, J = 6.6 Hz, 2H, 4-CH2), 3.38 (s,
3H, −OMe), 5.89 (d, J = 15.6 Hz, 1H, 2-CH), 7.01 (dt, J = 15.6,
6.6 Hz, 1H, 3-CH). GLC: retention time (min) = 22.03. Minor
species: retention time (min) = 31.43, 32.31.
2,4-Hexadiene with N,N-Dimethylacrylamide. Methyl
1
(2E,5Z)-4-methylocta-2,5-dienoate. Yield: 18%. H NMR (400 MHz,
C6D6, rt): δ 0.86 (t, J = 7.3 Hz, 3H, 8-Me), 0.98 (d, J = 6.9 Hz, 3H, 4-
CHMe), 1.90 (m, 2H, 7-CH2), 2.31 (s, 3H, −NMe2), 2.72 (s, 3H,
−NMe2), 3.16 (m, 1H, 4-CH), 5.17 (m, 1H, 5-CH), 5.37 (dt, J = 11.0,
6.9 Hz, 1H, 6-CH), 6.09 (d, J = 15.1 Hz, 1H, 2-CH), 7.15 (dd, J =
15.1, 6.9 Hz, 1H, 3-CH). GLC: retention time (min) = 33.23.
Myrcene with Methyl Acrylate. Methyl (3E,5Z)-6,10-dimethy-
lundeca-3,5,9-trienoate. Yield: 67%.1H NMR (400 MHz, C6D6, rt): δ
1.53 (s, 3H, 6, 10, or 11-Me), 1.59 (s, 3H, 6, 10, or 11-Me), 1.64 (s,
3H, 6, 10, or 11-Me), 1.91−2.13 (m, 4H, 7 and 8-CH2), 2.91 (d, J =
7.3 Hz, 2H, 2-CH2), 3.30 (s, 3H, −OMe), 5.11−5.18 (m, 1H, 9-CH),
5.71 (dt, J = 15.1, 7.3 Hz, 1H, 3-CH), 5.89 (d, J = 10.8 Hz, 1H, 5-CH),
6.29 (dd, J = 15.1, 10.8 Hz, 1H, 4-CH). GLC: retention time (min) =
34.43. Methyl (3E)-5-ethylydene-9-methylundeca-3,8-dienoate. Yield:
2,3-Dimethylbutadiene with 3-Buten-2-one. 1H NMR
(400 MHz, C6D6, rt): δ 1.47 (s, 6H, 6, 7, or 8-Me), 1.52 (s, 3H, 6,
7, or 8-Me), 1.84 (s, 3H, −COMe), 2.57 (d, J = 6.2 Hz, 2H, 3-CH2),
5.98 (d, J = 15.8 Hz, 1H, 5-CH), 6.43 (dt, J = 15.8, 6.2 Hz, 1H,
3-CH),. GLC: retention time (min) = 22.81. Minor species: retention
time (min) = 22.53.
1
2,3-Dimethylbutadiene with N,N-Dimethylacrylamide. (3E)-
N,N,5,6-Tetramethyl-3,5-heptadienylamide. Yield: 75%. 1H NMR
(400 MHz, C6D6, rt): δ 1.60 (s, 3H, 5, 6, or 7-CH3), 1.70 (s, 3H, 5,
6, or 7-CH3), 1.74 (s, 3H, 5, 6, or 7-CH3), 2.21 (s, 3H, −NMe2), 2.65
(s, 3H, −NMe2), 2.95 (d, J = 6.8 Hz, 1H, 2-CH), 5.92 (dt, J = 15.6,
6.8 Hz, 1H, 3-CH), 6.52 (d, J = 15.6 Hz, 1H, 4-CH). GLC: retention
time (min) = 37.95. Minor species: retention time (min) = 35.82, 37.07.
Isoprene with Methyl Acrylate. Methyl (3E)-6-methyl-3,5-
23%. H NMR (400 MHz, C6D6, rt): δ 1.37 (d, J = 6.9 Hz, 3H, 4
CHMe), 1.52 (s, 3H, 9 or 10-Me), 1.65 (s, 3H, 9 or 10-Me), 1.91−2.13
(m, 4H, 6 and 7-CH2), 2.61 (d, J = 6.4 Hz, 2H, 2-CH2), 3.41 (s, 3H,
−OMe), 5.11−5.18 (m, 1H, 8-CH), 5.25 (d, J = 6.9 Hz, 1H, 4
CHCH3), 5.91 (d, J = 15.6 Hz, 1H, 4-CH), 7.01 (dt, J = 15.6, 6.4 Hz,
1H, 3-CH). GLC: retention time (min) = 31.43.
Ru(η4-myrcene)(η4-1,5-COD)(NCMe). Treatment of 1 (178.0 mg,
0.5275 mg) with myrcene (91.0 μL, 0.528 mmol) in MeCN (6 mL) at
rt for 2 h and then at 50 °C for 2.5 h followed by the workup
procedure produced a light brown powder of Ru(η4-myrcene)(η4-1,5-
COD)(NCMe) in 54% yield (111.0 mg, 0.287 mmol). 1H NMR (400
MHz, rt, C6D6): δ 0.49 (d, J = 7.3 Hz, 1H, endo-1-CH), 0.59 (s, 1H,
endo-3′-CH), 0.74 (br s, 3H, NCMe), 1.66 (s, 3H, 7 or 8-Me), 1.74 (s,
3H, 8 or 7-Me), 1.74 (s, 1H, exo-3′-CH), 1.76 (d, J = 7.3 Hz, 1H, exo-1-
CH), 2.2−2.3 (m, 2H, 4-CH2), 2.6−2.7 (m, 2H, 5-CH2), 2.0−2.8
(overlapped, 8H, CH2 in COD), 2.86 (m, 1H, CH in COD), 3.17 (m,
1H, CH in COD), 3.53 (m, 1H, CH in COD), 3.75 (m, 1H, CH
in COD), 4.99 (t, J = 7.3 Hz, 1H, 2-CH), 5.53 (t, J = 7.3 Hz, 1H, 6-CH).
Computations. Density functional calculations37 were carried out
on compounds 2d, 3aa, and 3ca and on the model complexes 2dMA,
1
heptadienoate. H NMR (400 MHz, C6D6, rt): δ 1.52 (s, 3H, 6 or
7-Me), 1.58 (s, 3H, 6 or 7-Me), 2.91 (d, J = 7.1 Hz, 2H, 2-CH2), 3.31
(s, 3H, −OMe), 5.68 (dt, J = 15.0, 7.1 Hz, 1H, 3-CH), 5.80 (d, J =
11.1 Hz, 1H, 5-CH), 6.26 (dd, J = 15.0, 11.1 Hz, 1H, 4-CH). GLC:
retention time (min) = 22.54. Minor species: retention time (min) =
16.81, 19.37, 20.22, 21.93.
Isoprene with 3-Buten-2-one. (3E)-7-Methyl-3,6-octadien-2-
1
one. Yield: 23%. H NMR (400 MHz, C6D6, rt): δ 1.39 (s, 3H, 7 or
8-Me), 1.58 (s, 3H, 8 or 7-Me), 1.89 (s, 3H, −COMe), 2.55 (m, 2H,
5-CH2), 4.99 (t, J = 7.3 Hz, 1H, 5-CH), 6.00 (d, J = 15.7 Hz, 1H, 3-
CH), 6.41 (dt, J = 15.7, 6.4 Hz, 1H, 4-CH). GC: retention time (min)
= 20.73. (4E)-7-Methyl-4,6-octadien-2-one. Yield: 12%. 1H NMR
4017
dx.doi.org/10.1021/om300234d | Organometallics 2012, 31, 4006−4019

Organometallics
Article
AUTHOR INFORMATION
■
Corresponding Author
*Phone and Fax: +81 423 877 044. E-mail: hrc@cc.tuat.ac.jp.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank Ms. S. Kiyota for elemental analysis. We also wish to
thank Dr. M. T. Zamora for stimulating discussions. This work
was financially supported from the Ministry of Education,
Culture, Science and Technology of Japan.
3aa′, and 3ca′ using Spartan’0638 with the hybrid Becke 3LYP/6-31G*. All
relative energy values discussed and displayed throughout the computa-
tional section of this paper are in kJ mol−1 and were calculated at 298 K.
X-ray Structure Analysis. Single crystals suitable for X-ray structure
analysis were obtained from recrystallization of 3aePPh3, 3ca, and 3ea
from cold Et2O. A Rigaku AFC-7R-Mercury II diffractometer with graphite-
monochromated Mo Kα radiation (λ = 0.71075 Å) was used for data
collection at 200.0 K. A selected single crystal was mounted on a glass
capillary by use of Paraton N oil. The collected data were solved by direct
methods (SIR92) and refined by a full-matrix least-squares procedure using
SHELXL-97.39 All non-hydrogen atoms were refined with anisotropic
displacement parameters. Hydrogen atoms were placed using the riding
model. The crystallographic and refiment details are listed in Table 3.
REFERENCES
■
(1) (a) Ura, Y.; Sato, Y.; Shiotsuki, M.; Kondo, T.; Mitsudo, T. J. Mol.
Catal. A: Chem. 2004, 209, 35. (b) Ura, Y.; Sato, Y.; Tsujita, H.;
Kondo, T.; Imachi, M.; Mitsudo, T. J. Mol. Catal. A: Chem. 2005, 239,
166. (c) Kondo, T. Bull. Chem. Soc. Jpn. 2011, 84, 441.
(2) Ru(0)-catalyzed dimerization and trimetization of ethylene and
stryrene: (a) Kondo, T.; Yamamoto, K.; Takagi, D.; Shen, L.; Yoshida,
Y.; Kimura, Y.; Toshimitsu, A.; Kuramoto, M.; Shiraki, Y.
ChemCatChem 2010, 2, 1565. (b) Kondo, T.; Takagi, D.; Tsujita,
H.; Ura, Y.; Wada, K.; Mitsudo, T. Angew. Chem., Int. Ed. 2007, 46,
5958. N-Methyl-N-vinylacetamide with ethyl acrylate: Tsujita, H.;
Ura, Y.; Matsuki, S.; Wada, K.; Kondo, T. Angew. Chem., Int. Ed. 2007,
46, 5160.
Table 3. Crystallographic and Refinement Details for
3aePPh3, 3ca, and 3ea
(3) The term “oxidative coupling” is also used for the coupling of two
molecular entities through an oxidative process with an oxidant.
However, in this article, the oxidative coupling reaction is defined as
the metal-induced coupling reactions between two unsaturated
compounds to give a metallacycle: Crabtree, R. H. The Organo-
metallics Chemistry of the Transition Metals, 3rd ed.; Wiley: New York,
2001; p 168.
(4) Hirano, M.; Sakate, Y.; Komine, N.; Komiya, S.; Bennett, M. A.
Organometallics 2009, 28, 4902.
(5) Hirano, M.; Hiroi, Y.; Komine, N.; Komiya, S. Organometallics
2010, 29, 3690.
(6) Hiroi, Y.; Komine, N.; Hirano, M.; Komiya, S. Organometallics
2011, 30, 1307.
(7) Hirano, M.; Sakate, Y.; Komine, N.; Komiya, S.; Wang, X.-Q.;
Bennett, M. A. Organometallics 2011, 30, 768.
(8) Hirano, M.; Arai, Y.; Komine, N.; Komiya, S. Organometallics
2010, 29, 5741.
3aePPh3
3ca
3ea
formula
fw
C35H42NOPRu
624.77
C20H31NO2Ru
418.54
C22H35NO2Ru
446.59
cryst syst
space group
a (Å)
triclinic
triclinic
monoclinic
P21/c(No. 14)
14.246(5)
P1(No. 2)
P1(No. 2)
̅
̅
10.199(2)
10.922(3)
13.664(4)
82.687(6)
87.793(8)
76.674(8)
1468.9(6)
2
8.464(3)
10.961(3)
11.182(3)
84.032(10)
86.657(11)
69.827(6)
968.2(5)
2
b (Å)
14.126(5)
c (Å)
21.015(8)
α (deg)
β (deg)
γ (deg)
V (Å3)
Z
93.084(5)
4223(3)
8
temp (K)
200.0
200.0
200.0
cryst size (mm) 0.32 × 0.11 ×
0.27 × 0.06 ×
0.14 × 0.07 ×
0.08
0.03
0.07
(9) Witternberg, D. Angew. Chem. 1963, 75, 1124.
(10) Misono, A.; Uchida, Y.; Saito, T.; Uchida, K. Bull. Chem. Soc.
Jpn. 1967, 40, 1889.
(11) Tolstikov, G. A.; Dzhemilev, U. M.; Khusnutdinov, R. I. Z.
Obshch. Khim. 1975, 45, 1322.
color
pale yellow
652.00
yellow
pale yellow
1872.00
0.758
F(000)
μ (mm−1
436.00
0.821
)
0.617
absorp corr
radiation
numerical
numerical
numerical
(12) Singer, H.; Umbach, W.; Dohr, M. Synthesis 1971, 265.
Mo Kα (λ =
0.71075 Å)
Mo Kα (λ =
0.71075 Å)
Mo Kα (λ =
0.71075 Å)
(13) Bonnemann, H.; Grard, C.; Kopp, W.; Pump, W.; Tanaka, K.;
̈
diffractometer
Rigaku AFC7R-
Mercury II
Rigaku AFC7R-
Mercury II
Rigaku AFC7R-
Mercury II
Wilke, G. Angew. Chem., Int. Ed. Engl. 1973, 12, 964. (b) Bonnemann,
̈
H.; Grard, C.; Kopp, W.; Wilke, G. Pure Appl. Chem. 1971, 6, 265.
(14) Feldman, K. S.; Grega, K. C. J. Organomet. Chem. 1990, 381,
251.
measurement
method
ω
ω
ω
reflns (total)
params
6635
4370
9669
(15) Mitsudo, T.; Zhang, S.-W.; Kondo, T.; Watanabe, Y.
Tetrahedron Lett. 1992, 33, 341.
(16) The general mechanisms for olefin dimerization are summarized
in ref 4.
(17) Bennett, M. A.; Wang, X.-Q. J. Organomet. Chem. 1992, 428,
C17.
489
212
469
goodness of fit
1.053
1.227
1.012
a
R (Rw)
0.0302(0.0800)
0.0401(0.1183)
0.0962(0.2624)
a
R = ∑[|Fo| − |Fc|]/∑|Fo|. Rw = [∑w(|Fo|2 − |Fc|2)2/∑w|Fo]2]1/2
.
(18) Hirano, M.; Sakate, Y.; Inoue, H.; Arai, Y.; Komine, N.; Komiya,
S.; Wang, X.-Q.; Bennett, M. A. J. Organomet. Chem. 2012, 708−709,
46.
(19) Hirano, M.; Shibasaki, T.; Komiya, S.; Bennett, M. A.
Organometallics 2002, 21, 5738.
ASSOCIATED CONTENT
■
S
* Supporting Information
This material is available free of charge via the Internet at
http://pubs.acs.org.
(20) Funaioli, T.; Marchetti, F.; Fachinetti, G. Angew. Chem., Int. Ed.
2002, 41, 3905.
4018
dx.doi.org/10.1021/om300234d | Organometallics 2012, 31, 4006−4019

Organometallics
Article
(21) Baratta, W.; Del Zotto, A.; Rigo, P. Organometallics 1999, 18,
5091.
́
(22) Ferrando, G.; Coalter, J. N., III; Gerard, H.; Huang, D.;
Eisenstein, O.; Caulton, K. G. New J. Chem. 2003, 27, 1451.
(23) The molecular structures of 2aaPPh3 and 2aaCO are deposited
in the SI of the communication [ref 8].
(24) Muller, J.; Qiao, K.; Siewing, M.; Westphal, B. J. Organomet.
̈
Chem. 1993, 458, 219.
(25) (a) Tolstikov, G. A.; Dzhemilev, U. M.; Khusnutdinov, R. I. Zh.
Obshch. Khim. 1975, 45, 1322. (b) Ma, D.; Lu, X. Tetrahedron 1990,
46, 3189.
(26) Sanders, J. K. M.; Hunter, B. K. In Modern NMR Spectroscopy. A
Guide for Chemists, 2nd ed.; Oxford: New York, 1993; p 123.
(27) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. In
Principles and Applications of Organotransition Metal Chemistry,
University Science Books: Mill Valley, CA, 1987; p 177.
(28) The hydride in the hydridoruthenium(II) from Ru(COD)
(COT) was confirmed to come from the cyclopolyene ligand as an
internal reaction: Itoh, K.; Nagashima, H.; Ohshima, T.; Oshima, N.;
Nishiyama, H. J. Organomet. Chem. 1984, 272, 179.
(29) Fujiwara, M.; Nishikawa, T.; Hori, Y. Org. Lett. 1999, 1, 1635.
(30) Jolly, P. W.; Kopiske, C.; Kruger, C.; Limberg, A. Organo-
̈
metallics 1995, 14, 1885.
(31) (a) Zakharkin, K. I.; Petrushkina, E. A. Zh. Org. Khim. 1984, 20,
490. (b) Tolstikov, G. A.; Dzhemilev, U. M.; Khusnutdinov, R. I. Izvest.
Akad. Nauk SSSR, Ser. Khim. 1975, 1562.
(32) Recent reviews: (a) Behr, A.; Johnen, L. ChemSusChem 2009, 2,
1072. (b) Monteiro, J. L. F.; Veloso, C. O. Top. Catal. 2004, 27, 169.
(33) Biel, H.; Hamdi, N.; Zagrouba, F.; Fischmeister, C.; Bruneau, C.
Green Chem. 2011, 13, 1448.
(34) Bennett, M. A.; Lu, Z.; Wang, X.; Bown, M.; Hockless, D. C. R.
J. Am. Chem. Soc. 1998, 120, 10410.
(35) (a) Canonical structures between alkenyl and carbene ligands in
hydridomolybdenum(II): Ito, T.; Tosaka, H.; Yoshida, S.; Mita, K.;
Yamamoto, A. Organometallics 1986, 5, 735. (b) Dehydrogenative
isomerization from alkenyl to vinylidene in dinuclear Mn: García, F.
J.; Riera, V.; Ruiz, M. A.; Tripicchio, A.; Camellini, M. T.
Organmetallics 1992, 11, 370. (c) Alkenyl to vinylidene in Ru(II):
Olivan
2227. Olivan
́
, M.; Eisenstein, O.; Caulton, K. G. Organometallics 1997, 16,
́
, M.; Clot, E.; Eisenstein, O.; Caulton, K. G.
Organometallics 1998, 17, 3091. (d) Isomerization from alkenyl to
carbene by protonation: Sterenberg, B. T.; McDonald, R.; Cowie, M.
Organometallics 1997, 16, 2297. Jung, S.; Brandt, C. D.; Wolf, J.;
Werner, H. Dalton Trans. 2004, 375. (e) Equilibrium between alkenyl
and carbene in the presense of proton: Bodnar, T.; Cutler, A. R. J.
Organomet. Chem. 1981, 213, C31. (f) From vinylidene hydrido to
vinyl complex: Jung, S.; Ilg, K.; Wolf, J.; Werner, H. Organometallics
2001, 20, 2121. (g) Isomerization of olefin to carbene ligand:
Coalter, J. N., III; Bollinger, J. C.; Huffman, J. C.; Werner-Zwanziger,
́
U.; Caulton, K. G.; Davidson, E. R.; Gerard, H.; Clot, E.; Eisenstein, O.
New J. Chem. 2000, 24, 9. (h) γ-Chlorido elimination from γ-
chloropropenyl group: Wilhelm, T. E.; Belderrain, T. R.; Brown, S. N.;
Grubbs, R. H. Organometallics 1997, 16, 3867.
(36) Bennett, M. A.; Neumann, H.; Thomas, M.; Wang, X.-Q.;
Pertici, P.; Salvadori, P.; Vitulli, G. Organometallics 1991, 10, 3237.
(37) Ziegler, T. Can. J. Chem. 1995, 73, 743.
(38) Spartan’06; Wavefunction Inc., 1991−2006.
(39) Sheldrick, G. M. SHELXL-97; University of Gottingen:
̈
Gottingen, Germany, 1997.
̈
4019
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