Ru(0)-Catalyzed Direct Coupling of Internal Alkynes with Conjugated Dienes: An Efficient Access to Conjugated Trienes

Article abstract of DOI:10.1021/acs.organomet.6b00668

Ru(0)-catalyzed direct coupling of internal alkynes with conjugated dienes enables a direct access to conjugated trienes, where the reaction is formally regarded as a stereoselective syn alkyne insertion into the terminal C-H bond in the conjugated diene. The reaction is catalyzed by Ru(η⁶-naphthalene)(η⁴-1,5-COD) (1; 3-10 mol %) with high regio- and stereoselectivities.

Full text of DOI:10.1021/acs.organomet.6b00668

Article
pubs.acs.org/Organometallics
Ru(0)-Catalyzed Direct Coupling of Internal Alkynes with Conjugated
Dienes: An Efficient Access to Conjugated Trienes
Sayori Kiyota, Seonyong In, Ryo Saito, Nobuyuki Komine, and Masafumi Hirano*
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: Ru(0)-catalyzed direct coupling of internal alkynes
with conjugated dienes enables a direct access to conjugated
trienes, where the reaction is formally regarded as a stereo-
selective syn alkyne insertion into the terminal C−H bond in the
conjugated diene. The reaction is catalyzed by Ru(η6-
naphthalene)(η4-1,5-COD) (1; 3−10 mol %) with high regio-
and stereoselectivities.
by alkyne insertion into the C−H bond in a conjugated diene.
However, this attractive approach has not yet been reported to
the best of our knowledge. Note that Mitsudo,8 Suginome,9 and
co-workers have reported coupling reactions of terminal
alkynes with conjugated dienes catalyzed by Ru(II) and
Ni(0) complexes but these protocols do not produce
conjugated trienes but enynes.
INTRODUCTION
■
Conjugated trienes are important motifs in many natural
products, biologically active compounds, and electronic
materials.1 They are conventionally prepared by stoichiometric
reactions such as Wittig and Horner−Wadsworth−Emmons
reactions2 and alkyne/zirconacyclopentadiene coupling.3
Scheme 1 gives an overview of the current transition-metal-
We have reported cross-dimerization of alkenes with
conjugated dienes catalyzed by a Ru(0) complex that proceeds
by an oxidative coupling mechanism.10 We now report a
straightforward access to conjugated trienes by cross-dimeriza-
tion between internal alkynes and conjugated dienes.
Scheme 1. Simplified Concepts for Catalytic Production of
Conjugated Trienes
RESULTS AND DISCUSSION
■
Treatment of diphenylacetylene (2a) with methyl (2E,4E)-
penta-2,4-dienoate (3a) catalyzed by Ru(η6-naphthalene)(η4-
1,5-COD) (1; 10 mol %) at room temperature resulted in the
formation of methyl (2E,4E,6Z)-6,7-diphenylhepta-2,4,6-trien-
oate (4aa) in 84% NMR yield within 10 min without formation
of any isomers. The stereochemistry of 4aa was determined by
NMR experiments involving pNOESY. Adopting the above as a
standard set of conditions, we evaluated the scope of alkynes
with 3a. With 1,2-bis(4-methylphenyl)acetylene (2b), 1,2-
bis(4-trifluoromethylphenyl)acetylene (2c), and 1,2-bis(4-
nitrophenyl)acetylene (2d), the corresponding conjugated
trienes (2E,4E,6Z)-4ba, -4ca,11 and -4da were obtained in
moderate to high NMR yields, suggesting no significant
electronic effect among diarylacetylenes on the reactivity
(Table 1). Unlike the case for 4aa, (2E,4E,6Z)-4ba and
(2E,4E,6Z)-4ca were produced along with the isomers in 4%
and ∼10% yields, respectively, although their detailed structures
wereare not clear at present. Isolated yields were lower, ranging
from 9% to 60% for 4aa−4ed.
catalyzed approaches. Namely, these strategies involve Mizor-
oki−Heck reactions,4 cross-coupling reactions,5 intermolecular
ring-opening reactions,6 and alkyne/alkene coupling reactions.7
However, these processes have somewhat limited scopes with
respect to both coupling partners, and those using organic
halides are problematic from an atom-economical point of view.
A more straightforward and greener strategy to prepare
conjugated trienes could be a catalytic conjugate expansion
Received: August 22, 2016
© XXXX American Chemical Society
A
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Table 1. Direct Coupling of Alkynes with Conjugated
Dienes
Scheme 2. Reactions using Unsymmetrical Internal Alkynes
a
a
Typical conditions: 1 (10 mol %), 2 (0.2 mmol), 3 (0.2 mmol), room
temperature, time 10 min to 1 h, solvent benzene. Yields were
Scheme 3. Reactions using 1,4-, 1,3-, and 1,2-Bis(1-
pentynyl)benzenes
estimated by 1H NMR using triphenylmethane as an internal standard.
Electron-rich 3-hexyne (2e) also reacted with 3a to give
(2E,4E,6E)-4ea in 76% NMR yield. With an extremely
electron-deficient alkyne, such as dimethyl acetylenedicarbox-
ylate or ethyl 1-pentynoate, and terminal alkynes such as
phenylacetylene and 1-hexyne complex mixtures were obtained.
The reaction did not occur with 2,4-hexadiyne even at 50 °C.
The scope of the conjugated dienes was evaluated with 3-
hexyne (2e). In addition to the electron-deficient 3a, 1-phenyl-
1,3-butadiene (3b) and electron-rich 1,3-pentadiene (3c) are
also excellent coupling partners in this reaction. An internal
diene, methyl (2E,4E)-hexa-2,4-dienoate (3d), also reacted with
2e to give 4ed, although the product yield was not high.
Notably, this reaction requires a formal CC bond rotation in
3d (vide infra). Danishefski−Kitahara diene12 remained
unreacted even at 50 °C. By a similar token, 1,3-dienes bearing
a substituent at the C(2) position, such as isoprene, 2,3-
dimethylbutadiene (3e) and β-myrcene, did not undergo direct
coupling.
Unsymmetrical internal alkynes are interesting coupling
partners from a regioselectivity point of view. Although it was
difficult to control the regioselectivity of 2-hexyne (2f) in the
formation of 4fa (4fa/4fa′ = 50/50), a highly regioselective
coupling of 1-phenyl-1-propyne (2g) with 3a was achieved to
give (2E,4E,6E)-4ga in 70% yield and the regioisomer
(2E,4E,6Z)-4ga′ in 4% yield (Scheme 2) along with
unidentified isomers.
4ia in 97% yield. With 1,2-bis(1-pentynyl)benzene (2j), NMR
experiments suggested that the reaction produced an initial
product having a new propyl group, putatively assigned as 1-
alkynyl-2-trienylbenzene, which gradually converted into a
complex mixture.
In order to understand the reaction mechanism for this
process, we performed the reaction of 2a with 1-phenyl-
[4,4′-2H2]-1,3-butadiene (3b-d2) (eq 1). This reaction
produced (1Z,3E,5E)-[1,3-2H2]-4ab-d2 in 82% yield, and the
deuterium atoms were observed at the C(1) and C(3)
With this promising regioselectivity in hand, our next
challenge was coupling reactions using dialkynylbenzenes.
Treatment of 1,4-bis(1-pentynyl)benzene (2h) with 2.6 equiv
of 3a in the presence of 1 (10 mol %) deposited a yellow-
brown precipitate of (1E,1′E,3E,3′E,5E,5′E)-4ha, whose regio-
and stereochemistries were fully characterized by NMR
experiments (Scheme 3).13 Similar treatment of 1,3-bis(1-
pentynyl)benzene (2i) also produced (1E,1′E,3E,3′E,5E,5′E)-
1
2
positions, which were shown by H and H NMR. This result
clearly demonstrates the formal syn addition of the C−D bond
in 3b-d2 to 2a.
Bennett’s group and our group documented the facile
formation of the cisoid-conjugated diene complexes of Ru(0)
by reaction of 1 with a series of conjugated dienes,14,15 and
B
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Ru(η4-methyl penta-2,4-dienoate)(η4-1,5-COD)(NCMe) (5a)
was also prepared accordingly. Treatment of 5a with 2a
instantly gave Ru[η4-methyl (2E,4E,6E)-6,7-diphenylpenta-
2,4,6-trienoate](η4-1,5-COD) (6aa) in 52% yield at room
temperature (Scheme 4). The pNOESY measurements suggest
Figure 1. Molecular structure of supine,prone-7a. Ellipsoids represent
50% probability.
Scheme 4. Stoichiometric Reaction of Conjugated Diene
Complex 5a with Diphenylacetylene (2a)
Scheme 5. Stoichiometric Reaction of Conjugated Diene
Complex 5e with Diphenylacetylene (2a)
1
a cisoid conformation of the C(2)−C(5) fragment. The H
NMR resonances for C(2)−H (δ 4.24(d)), C(5)−H (δ
2.93(d)), and C(7)−H (δ 5.16(s)), and the 13C{1H} NMR
resonances at C(2) (δ 39.19), C(5) (δ 85.30), C(6) (δ 112.83),
and C(7) (δ 51.38) are basically consistent with the proposed
structure with some contribution of the interaction between the
C(6)C(7) fragment and the Ru(0) center.
conditions. This means that the coordinated 3e does react with
2a at the Ru(0) center but the resulting triene ligand in 6ae
cannot be replaced with 3e. This is one of the reasons some
conjugated dienes are inactive in the present catalysis. Because
6ae does not react with 3a as well, the failure of the reaction of
6ae with a diene does not arise from the employed diene but
from the inert nature of 6ae toward dienes.
All of these experimental results are consistent with the
catalytic cycle shown in Scheme 6. The naphthalene ligand
(6π) is readily displaced by a conjugated diene (4π) and alkyne
(2π) to satisfy the 18e rule to give A, which determines the
substrate selectivity in this reaction. We tentatively denote the
terminal methylene protons of the cisoid-diene ligand in A as
Further treatment of 6aa with 2 equiv of 3a gave (2E,4E,6Z)-
4aa in 91% yield with formation of 7a in 55% yield, which was
independently obtained by treatment of 5a with 3a. The
molecular structure of 7a is shown in Figure 1, which is well
described as a supine,prone-η3:η3-bis(allylic)ruthenium(II),
suggesting that the oxidative coupling reaction occurred
between cisoid-η4-(methyl penta-2,4-dienoate) and transoid-η2-
(methyl penta-2,4-dienoate) fragments at the Ru(0) cen-
ter.15b,16
H
endo and Hexo. Then the oxidative coupling reaction produces a
A similar stoichiometric reaction of 5a with 3-hexyne (2e)
completely consumed the starting compounds and gave a
complex mixture involving (2E,4E,6E)-4ea in 36% yield, and
further treatment of the mixture with 1 equiv of 3a gave
(2E,4E,6E)-4ea in 80% yield with recovery of 5a in 63% yield.
These two stoichiometric reactions are regarded as stepwise
reactions of a part of the catalytic process. On the other hand, a
similar reaction using 2,3-dimethylbutadiene (3e) is worth
noting from a mechanistic point of view. Treatment of Ru(η4-
2,3-dimethylbutadiene)(η4-1,5-COD)(NCMe) (5e) with 2a
also produced Ru[η4-1,2-diphenyl-4,5-dimethylhexa-1,3,5-
triene](η4-1,5-COD) (6ae) in 51% yield (Scheme 5).
ruthenacycle (B). Without exception, we obtain the E products
with respect to the central CC bond in conjugated trienes.
This fact means that the subsequent β-hydride elimination
selectively occurs at Hendo to give C. Thus, unlike the working
hypothesis shown in Scheme 1, a terminal C−Hendo bond in a
conjugated diene has been cleaved (Scheme 6). This probably
enables the reaction using an internal diene (2E,4E)-3d to give
4ed. The reductive elimination from C produces the transoid-
triene complex D, which eventually isomerizes to the cisoid-
triene complex E.17 This is precisely same as 6aa obtained by
the stoichiometric reaction.
Finally, replacement of the conjugated triene ligand by
incoming 2 and 3 releases the conjugated triene product 4 with
regeneration of A.
Unlike 6aa, however, 6ae never reacted with 3e. Note that no
reaction occurred between 2a and 3e under the catalytic
C
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the features of the present reaction is the high regio- and
stereoselectivity. Because alkynylarenes are readily available by
the Sonogashira coupling reaction, this catalysis also provides a
wide range of conjugated trienylarenes.
Scheme 6. Proposed Mechanism
EXPERIMENTAL SECTION
■
General Procedures. All procedures described in this
paper were carried out under a nitrogen or argon atmosphere
by use of Schlenk and vacuum line techniques. Benzene,
toluene, hexane, THF, and Et2O were dried and purified using
an Ultimate Solvent System. Acetone was dried over Drierite
and distilled under nitrogen. Benzene-d6 was dried over sodium
wire and stored under vacuum, and it was transferred into an
NMR tube or a 25 mL Schlenk tube by vacuum distillation
prior to use. Chloroform-d was dried over P2O5 or its
equivalent and stored under vacuum. Phenylacetylene (2a),
methyl (2E,4E)-penta-2,4-dienoate (3a) (containing 8% of the
stereoisomer), trans-1-phenyl-1,3-butadiene (3b), trans-1,3-
pentadiene (3c), and methyl sorbate (3d) were purchased
from commercial suppliers and stored under a nitrogen
atmosphere after three freeze−pump−thaw cycles. Ru(η6-
naphthalene)(η4-1,5-COD) (1), 1,2-diarylacetylenes 2b−d,
and diynes 2h,i were prepared according to the literature
procedures.18−22 1-Phenyl-[4,4′-2H2]-1,3-butadiene (3b-d2)
was prepared according to a related literature procedure.23
Typical Reaction of Diphenylacetylene (2a) with
Methyl Penta-2,4-dienoate (3a) To Give (2E,4E,6Z)-4aa.
The DFT calculations using 2-butyne and 1,3-butadiene are
also consistent with this mechanism, and the energy diagram
suggests that this reaction can proceed at room temperature
(Figure 2).
Method A. In a 25 mL Schlenk tube was placed
diphenylacetylene (2a; 99.8 mg, 0.600 mmol). After addition
of benzene (1.0 mL), methyl penta-2,4-dienoate (3a; 65.0 μL,
0.559 mmol), and Ru(η6-naphthalene)(η4-1,5-COD) (1; 19.4
mg, 0.0576 mmol) under a nitrogen atmosphere, the reaction
mixture was stirred at room temperature for 1 h. All volatile
materials were removed under reduced pressure. Recrystalliza-
tion of the resulting solid from cold Et2O gave colorless needles
of 4aa (36.5 mg, 0.126 mmol) in 22% yield. The other
compounds obtained by method A were also prepared in a
similar way.
Method B. Complex 1 (6.01 mg, 0.0178 mmol) was placed
in an NMR tube under a nitrogen atmosphere, and 2a (31.9
mg, 0.179 mmol) and benzene-d6 (550 μL) were added. To the
solution was added 3a (21.0 μL, 0.181 mmol) by a hypodermic
syringe at room temperature. The mixture was allowed to react
at room temperature for 10 min, during which time the reaction
was monitored by 1H NMR spectroscopy. In order to
determine the yield of the product, triphenylmethane (12.4
mg, 0.0508 mmol) was added to the reaction mixture as an
internal standard. The yield of (2E,4E,6Z)-4aa was estimated as
84% along with a tiny amount of the minor isomer. The other
compounds obtained by method B were also prepared in a
Figure 2. Energy diagram by DFT calculations for the coupling
reaction of 2-butyne with 1,3-butadiene. The free energies of activation
on the basis of each step are shown in parentheses in kcal mol−1. Basis
sets: B3LYP/LANL2DZ for Ru and 6-31G(d) for C and H, benzene
(PCM).
CONCLUDING REMARKS
■
1
In summary, we have developed a new protocol for the
conjugated triene synthesis by the direct coupling reaction
between internal alkynes and conjugated dienes. The reaction
proceeds well with a wide range of internal alkynes and
conjugated dienes. This new catalysis is also regarded as a direct
conjugate expansion of conjugated dienes using alkynes. One of
similar way. H NMR (400 MHz, C6D6, room temperature): δ
3
3.40 (s, 3H, −CO2Me), 5.57 (d, JH−H = 15.4 Hz, 1H, 2-CH),
3
5.96 (dd, JH−H = 14.9, 11.5 Hz, 1H, 4-CH), 6.46 (s, 1 H, 7-
CH), 6.53 (d, 3JH−H = 14.9 Hz, 1H, 5-CH), 6.85−6.91 (m, 5H,
C6H4), 7.00−7.03 (m, 2H, C6H4), 7.07−7.12 (m, 3H, C6H4),
3
7.60 (dd, JH−H = 15.4, 11.5 Hz, 1H, 3-CH). 13C{1H} NMR
D
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(100.5 MHz, C6D6, room temperature): δ 51.0, 121.2, 129.1,
129.3, 129.6, 130.1, 135.7, 136.7, 138.0, 141.3, 144.7, 145.9,
167.1. MS (EI): m/z 290 (M+). Anal. Calcd for C20H18O2
(290.36): C, 82.73; H, 6.25. Found: C, 82.54; H, 6.47.
Reaction of 1,2-Bis(4-methylphenyl)acetylene (2b)
with Methyl Penta-2,4-dienoate (3a) To Give
(2E,4E,6Z)-4ba.
standard, the yield of (2E,4E,6Z)-4ca was estimated as 67%
1
along with an unidentified minor isomer (∼10%). H NMR
(400 MHz, CDCl3, room temperature): δ 3.72 (s, 3H,
3
−CO2Me), 5.79 (d, JH−H = 15.4 Hz, 1H, 2-CH), 5.88 (dd,
3JH−H = 15.5, 11.4 Hz, 1H, 4-CH), 6.81 (s, 1 H, 7-CH), 6.91 (d,
3
3JH−H = 15.5 Hz, 1H, 5-CH), 6.94 (d, JH−H = 8.0 Hz, 2H,
C6H4), 7.28 (d, 3JH−H = 8.0 Hz, 2H, C6H4), 7.36 (d, 3JH−H = 8.6
Hz, 2H, C6H4), 7.37 (1H, 3-CH, overlapped with resonances
for C6H4), 7.69 (d, 3JH−H = 8.6 Hz, 2H, C6H4). 19F NMR (376
MHz, CDCl3, room temperature): δ −62.7 (s, 3F, CF3), −62.4
(s, 3F, CF3). 13C{1H} NMR (100.5 MHz, CDCl3, room
temperature): δ 51.6, 122.0, 125.2, 126.2, 129.6, 129.8, 130.2,
134.0, 139.0, 140.7, 141.5, 143.8, 144.0, 167.3. MS (EI): m/z
426 (M+). HRMS (APCI): C22H16F6O2 (426.36) m/z
427.1138 [M + 1H]+, calcd for C22H17F6O2 427.1127.
Using method A, the reaction of 1,2-bis(4-methylphenyl)-
acetylene (2b; 130.0 mg (18% diyne included), 0.5168 mmol)
and 3a (65.0 μL, 0.559 mmol) in the presence of 1 (19.9 mg,
0.0591 mmol) proceeded at room temperature for 1 h.
Recrystallization of the resulting crude product from cold
Et2O gave pale yellow needles of 4ba (46.9 mg, 0.147 mmol) in
29% yield. Using method B, the reaction of 2b (34.2 mg, 0.166
mmol) with 3a (18.5 μL, 0.159 mmol) catalyzed by 1 (5.41 mg,
0.0160 mmol) in an NMR tube proceeded at room temperature
for 22.5 h. On the basis of triphenylmethane (6.81 mg, 0.0279
mmol) as an internal standard, (2E,4E,6Z)-4ba was obtained in
70% yield along with a tiny amount of the minor isomer (4%).
1H NMR (400 MHz, C6D6, room temperature): δ 1.94 (s, 3H,
−Me), 2.10 (s, 3H, −Me), 3.40 (s, 3H, −CO2Me), 5.62 (d,
Reaction of 1,2-Bis(4-nitrophenyl)acetylene (2d) with
Methyl Penta-2,4-Dienoate (3a) To Give (2E,4E,6Z)-4da.
Using method A, the reaction of 1,2-bis(4-nitrophenyl)-
acetylene (2d; 119.1 mg, 0.444 mmol) with 3a (53.0 μL,
0.456 mmol) was catalyzed by 1 (15.8 mg, 0.0469 mmol) at
room temperature for 40.5 h. All volatile materials were
removed under reduced pressure. After recrystallization from
cold chloroform and recycle HPLC using a GPC column, the
resulting solid gave a yellow powder of 4da (15.0 mg, 0.0394
mmol) in 9% yield. Using method B, the reaction of 2d (39.9
mg, 0.149 mmol) with 3a (18.0 μL, 0.155 mmol) was catalyzed
by 1 (5.14 mg, 0.0152 mmol) in benzene-d6 (600 μL) at room
temperature for 22 h. On the basis of triphenylmethane (8.22
mg, 0.0336 mmol) as an internal standard, the yield of
(2E,4E,6Z)-4da was estimated as 78% along with a tiny amount
3
3JH−H = 15.0 Hz, 1H, 2-CH), 6.04 (dd, JH−H = 14.9, 11.2 Hz,
1H, 4-CH), 6.52 (s, 1H, 7-CH), 6.60 (d, 3JH−H = 14.9 Hz, 1H,
3
3
5-CH), 6.73 (d, JH−H = 8.0 Hz, 2H, C6H4), 6.92 (d, JH−H
=
8.0 Hz, 2H, C6H4), 6.99 (d, 3JH−H = 8.4 Hz, 2H, C6H4), 7.01 (d,
3JH−H = 8.4 Hz, 2H, C6H4), 7.64 (dd, JH−H = 15.0, 11.2 Hz,
3
1H, 3-CH). 13C{1H} NMR (100.5 MHz, C6D6, room
temperature): δ 21.0, 21.2, 51.0, 120.8, 128.6, 129.2, 129.7,
130.09, 130.11, 134.2, 135.3, 135.8, 137.3, 137.7, 140.6, 144.9,
146.4, 167.3. MS (EI): m/z 318 (M+). HRMS (APCI):
C22H22O2 (318.42) m/z 319.1694 [M + 1H]+, calcd for
C22H23O2 319.1693.
1
of the minor isomer. H NMR (400 MHz, CDCl3, room
3
temperature): δ 3.73 (s, 3H, −CO2Me), 5.81 (d, JH−H = 14.9
3
Reaction of 1,2-Bis(4-trifluoromethylphenyl)-
acetyelene (2c) with Methyl Penta-2,4-dienoate (3a) To
Give (2E,4E,6Z)-4ca.
Hz, 1H, 2-CH), 5.90 (dd, JH−H = 15.2, 11.5 Hz, 1H, 4-CH),
6.88 (s, 1H, 7-CH), 6.92 (d, 3JH−H = 14.9 Hz, 1H, 5-CH), 6.99
(AA′BB′, 3JH−H = 8.6 Hz, 4JH−H = −0.5 Hz, 5JH−H = 0.5 Hz, 2H,
3
4
5
C6H4), 7.35 (AA′BB′, JH−H = 8.6 Hz, JH−H = −0.5 Hz, JH−H
= 0.5 Hz, 2H, C6H4), 7.60 (1 H, 3-CH, overlapped with
3
4
resonances for C6H4), 7.97 (AA′BB′, JH−H = 8.8 Hz, JH−H
=
5
3
−1.0 Hz, JH−H = 0.1 Hz, 2H, C6H4), 8.31 (d, JH−H = 8.8 Hz,
4JH−H = −1.0 Hz, JH−H = 0.1 Hz, 2H, C6H4). 13C{1H} NMR
5
(100.5 MHz, CDCl3, room temperature): δ 51.6, 123.0, 123.6,
124.6, 130.0, 130.4, 131.3, 133.3, 141.7, 142.3, 142.9, 143.3,
143.5, 146.7, 147.8, 167.1. MS (EI): m/z 380 (M+). HRMS
(APCI): C20H16N2O6 (380.36) m/z 381.1076 [M + 1H]+, calcd
for C20H17N2O6 381.1081.
Reaction of 3-Hexyne (2e) with Methyl Penta-2,4-
Dienoate (3a) To Give (2E,4E,6E)-4ea.
Using method A, the reaction of 1,2-bis(4-
trifluoromethylphenyl)acetylene (2c; 120 mg, 0.382 mmol)
with 3a (50.0 μL, 0.430 mmol) catalyzed by 1 (10.1 mg, 0.0299
mmol) proceeded at room temperature for 14 h. A yellow
precipitate deposited from the solution, which was separated by
a cannula tube. After the precipitate was washed three times
with benzene (1 mL), the dried precipitate under vacuum was
recrystallized from cold Et2O to give 4ca as analytically pure
colorless needles (30.8 mg, 0.0722 mmol) in 19% yield. Using
method B, the reaction of 2c (49.7 mg, 0.158 mmol) with 3a
(18.5 μL, 0.159 mmol) catalyzed by 1 (5.41 mg, 0.0160 mmol)
proceeded at room temperature for 12 h. On the basis of
triphenylmethane (8.67 mg, 0.0355 mmol) as an internal
Using method A, the reaction of 3-hexyne (2e; 100.0 μL, 0.860
mmol) with 3a (100.0 μL, 0.880 mmol) was catalyzed by 1
(11.3 mg, 0.0333 mmol) at room temperature for 1 h. After the
E
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reaction mixture was evaporated, the crude product was directly
purified by flash chromatography using silica gel (hexane/Et2O
= 9/1) to give a yellow oil of (2E,4E,6E)-4ea (99.4 mg, 0.512
mmol) in 60% yield. Using method B, the reaction of 3-hexyne
(2e; 26.0 μL, 0.229 mmol) with 3a (27.0 μL, 0.232 mmol) was
catalyzed by 1 (7.8 mg, 0.023 mmol) in C6D6 (600 μL) at room
temperature for 10 min. On the basis of triphenylmethane
(18.0 mg, 0.0737 mmol) as an internal standard, the product
was determined by NMR and GLC/GC-MS to be (2E,4E,6E)-
4ea (76% yield) and isomer (15% yield). 1H NMR (400 MHz,
Reaction of 1-Phenyl-1-Propyne (2g) with Methyl
Penta-2,4-dienoate (3a) To Give (2E,4E,6E)-4ga and
(2E,4E,6Z)-4ga′.
Using method A, the reaction of 1-phenyl-1-propyne (2g; 170
μL, 1.38 mmol) with 3a (170 μL, 1.46 mmol) was catalyzed by
1 (51.2 mg, 0.152 mmol) at room temperature for 1 day, during
which time a white precipitate deposited from the solution. The
precipitate was separated by a cannula tube. After the
precipitate was washed with hexane, the precipitate was dried
under reduced pressure to give 4ga as an analytically pure white
powder (125.1 mg, 0.548 mmol) in 40% yield. In addition to
the precipitate, 4ga was also obtained from the mother liquor
and the crude product was purified by flash chromatography
using silica gel (hexane/ethyl acetate 1/0 to 30/1) to give a
yellow oil of methyl (2E,4E,6E)-6-methyl-7-phenylhepta-2,4,6-
triene ((2E,4E,6E)-4ga; 111.4 mg, 0.488 mmol). The total yield
of (2E,4E,6E)-4ga was 75%. The regioisomer, methyl
(2E,4E,6Z)-6-phenylocta-2,4,6-triene ((2E,4E,6Z)-4ga′), was
also obtained in 4% yield. Using method B, the reaction of 1-
phenyl-1-propyne (2g; 25.0 μL, 0.203 mmol) with methyl 2,4-
pentadienoate (3a; 24.0 μL, 0.206 mmol) was catalyzed by 1
(6.8 mg, 0.020 mmol) at room temperature for 5 min. The
3
C6D6, room temperature): δ 0.82 (t, JH−H = 7.4 Hz, 3H, 9-
CH3), 0.86 (t, 3JH−H = 7.4 Hz, 3H, 11-CH3), 1.90 (quint, 3JH−H
3
= 7.4 Hz, 2H, 8-CH2), 2.03 (q, JH−H = 7.4 Hz, 2H, 10-CH2),
3
3.48 (s, 3H, 1-CO2CH3), 5.34 (t, JH−H = 7.4 Hz, 1H, 7-CH),
3
3
5.91 (d, JH−H = 14.9 Hz, 1H, 2-CH), 6.12 (dd, JH−H = 15.2,
10.9 Hz, 1H, 4-CH), 6.22 (d, 3JH−H = 15.5 Hz, 1H, 5-CH), 7.52
(dd, JH−H = 15.2, 10.9 Hz, 1H, 3-CH). 13C{1H} NMR (100
3
MHz, C6D6, room temperature): δ 13.74, 13.99, 19.77, 21.77,
50.97, 119.80, 123.72, 139.26, 139.66, 144.82, 145.85, 167.20.
MS (EI): m/z 194 (M+). HRMS (APCI): C12H18O2 (194.27)
m/z 195.1377 [M + 1H]+, calcd for C12H19O2 195.1380.
Reaction of 2-Hexyne (2f) with Methyl Penta-2,4-
Dienoate (3a) To Give (2E,4E,6E)-4fa and (2E,4E,6E)-4fa′.
1
reaction was monitored by H NMR spectroscopy. Yields:
(2E,4E,6E)-4ga, 70%; (2E,4E,6Z)-4ga′, 4%. Along with these
In an NMR tube was placed 1 (7.24 mg, 0.0215 mmol), and
benzene-d6 (600 μL) was introduced into the tube by vacuum
distillation. Then 2-hexyne (24.0 μL, 0.214 mmol) and 3a (25.0
μL, 0.215 mmol) were added by a hypodermic syringe at room
temperature. After 10 min, dibenzyl (6.60 mg, 0.0362 mmol,
internal standard) was added to the reaction mixture as an
internal standard. The yield of the product was determined by
1H NMR and by GLC and GC-MS. The total yields of
(2E,4E,6E)-4fa and -4fa′ were estimated as 70% (4fa/4fa′ =
50/50) along with a minor isomer. Data for 4fa are as follows.
1H NMR (400 MHz, C6D6, room temperature): δ 0.78 (t,
3JH−H = 7.4 Hz, 3H, 10-Me, overlapped with resonances for
10′−Me), 1.18−1.28 (m, 1H, 9-CH2, overlapped with
products, unidentified isomers (m/z 228) were also formed in
1
28% yield. Data for (2E,4E,6E)-4ga are as follows. H NMR
(400 MHz, C6D6, room temperature): δ 1.70 (s, 3H, 8-Me),
3
3.49 (s, 3H, 1-CO2Me), 5.96 (d, JH−H = 15.5 Hz, 1H, 2-CH),
3
3
6.13 (dd, JH−H = 15.2, 11.4 Hz, 1H, 4-CH), 6.35 (d, JH−H
=
15.5 Hz, 1H, 5-CH), 6.39 (s, 1H, 7-CH), 7.3−7.0 (m, 5 H, Ph),
7.57 (dd, 3JH−H = 15.1, 11.4 Hz, 1H, 3-CH). MS (EI): m/z 228
(M+). Anal. Calcd for C15H16O2 (228.29): C, 78.92; H, 7.06.
Found: C, 78.67; H, 6.62. Data for (2E,4E,6Z)-4ga′ are as
follows. 1H NMR (400 MHz, C6D6, room temperature): δ 1.39
3
(d, JH−H = 7.4 Hz, 3H, Me), 3.39 (s, 3H, 1-CO2Me), 5.57 (d,
3
3JH−H = 15.8 Hz, 1H, 2-CH), 5.58 (q, JH−H = 7.2 Hz, 1H, 7-
3
CH), 5.88 (dd, JH−H = 15.2, 11.4 Hz, 1H, 4-CH), 6.42 (d,
3JH−H = 14.9 Hz, 1H, 5-CH), 7.3−7.0 (m, 5H, Ph), 7.56 (dd,
3JH−H = 16.3, 11.4 Hz, 1H, 3-CH). MS (EI): m/z 228 (M+).
This minor compound was only characterized by spectroscopic
methods.
3
resonances for 9′-CH2), 1.50 (s, 3H, 11−Me), 1.90 (q, JH−H
= 7.5 Hz, 2H, 8-CH2), 2.73 (s, 3H, 1-CO2Me, overlapped with
resonances for 1′-CO2Me), 5.39−5.43 (br, 1H, 7-CH, over-
3
lapped with resonances for 7′-CH), 5.95 (d, JH−H = 15.4 Hz,
Reaction of Diphenylacetylene (2a) with 1-Phenyl-
1,3-Butadiene (3b) To Give (1Z,3E,5E)-4ab.
3
1H, 2-CH), 6.05 (dd, JH−H = 15.2, 10.9 Hz, 1H, 4-CH), 6.29
3
3
(d, JH−H = 15.5 Hz, 1H, 5-CH), 7.56 (dd, JH−1H = 15.4, 10.9
Hz, 1H, 3-CH). Data for 4fa′ are as follows. H NMR (400
MHz, C6D6, room temperature): δ 0.78 (t, 3JH−H = 7.4 Hz, 3H,
10′-Me, overlapped with resonances for 10-CH3), 1.18−1.28
(m, 1H, 9′-CH2, overlapped with resonances for 9-CH2), 1.47
3
3
(d, JH−H = 7.8 Hz, 3H, 11′-Me), 2.03 (t, JH−H = 7.4 Hz, 2H,
8′-CH2), 2.73 (s, 3H, 1′-CO2Me, overlapped with resonances
for 1-CO2Me), 5.39−5.43 (br, 1H, 7′-CH, overlapped with
Using method A, the reaction of diphenylacetylene (2a; 109.12
mg, 0.6122 mmol) with 1-phenyl-1,3-butadiene (3b; 90.0 μL,
0.642 mmol) was catalyzed by 1 (20.43 mg, 0.0605 mmol) at
room temperature for 1 h. After workup procedures, the crude
product was obtained as a brown solid (179.4 mg). A part of
the product (54.3 mg) purified by recycle HPLC gave a pale
yellow powder of (1Z,3E,5Z)-4ab (16.7 mg, 0.0541 mmol) in
3
resonances for 7-CH), 5.92 (d, JH−H = 14.9 Hz, 1H, 2′-CH),
6.12 (dd, 3JH−H = 15.5, 10.3 Hz, 1H, 4′-CH), 6.20 (d, 3JH−H J =
3
15.5 Hz, 1H, 5′-CH), 7.53 (dd, JH−H = 14.9, 10.6 Hz, 1H, 3′-
CH). MS (EI): m/z 194 (M+). These compounds were
characterized by spectroscopic methods.
F
DOI: 10.1021/acs.organomet.6b00668
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
9% yield. Using method B, the reaction of 2a (32.1 mg, 0.180
mmol) with 3b (25.0 μL, 0.177 mmol) was catalyzed by 1 (5.94
mg, 0.0176 mmol) in benzene (600 μL) at room temperature
temperature for 1 h. After the reaction mixture was evaporated,
the crude product was directly purified by flash chromatog-
raphy using silica gel (hexane) to give a colorless liquid of
(2E,4E,6E)-4ec (26.4 mg, 0.176 mmol) in 21% yield. Using
method B, the reaction of 3-hexyne (2e; 30.0 μL, 0.264 mmol)
with 3c (30.0 μL, 0.301 mmol) was catalyzed by 1 (9.8 mg,
0.029 mmol) in benzene-d6 (600 μL) at room temperature for
5 min. On the basis of dibenzyl (13.5 mg, 0.0741 mmol) as an
internal standard, the product was determined by NMR and
1
for 1 h to give (1Z,3E,5E)-4ab in 81% yield. H NMR (400
3
MHz, CDCl3, room temperature): δ 5.94 (dd, JH−H = 14.9,
12.9 Hz, 1H, 4-CH), 6.37 (d, 3JH−H = 15.5 Hz, 1H, 6-CH), 6.57
(s, 1H, 1-CH), 6.69 (d, 3JH−H = 14.9 Hz, 1H, 3-CH), 6.81−6.83
3
(m, 2H, Ph), 6.85 (dd, JH−H = 15.5, 10.9 Hz, 1H, 5-CH),
3
7.00−7.05 (m, 3H, Ph), 7.12−7.16 (m, 3H, Ph), 7.23 (t, JH−H
1
1
= 7.4 Hz, 2H, Ph), 7.30−7.39 (m, 5H, Ph). H NMR (400
GLC/GC-MS. Yields: (2E,4E,6E)-4ec, 77%; isomer, 5%. H
MHz, C6D6, room temperature): δ 6.07 (d, 3JH−H = 15.4 Hz, 1
H, 6-CH), 6.19 (dd, 3JH−H = 15.4, 10.6 Hz, 1 H, 4-CH), 6.63 (s,
NMR (400 MHz, C6D6, room temperature): δ 0.90 (t, 3JH−H
=
3
7.4 Hz, 3H, 9-Me), 1.01 (t, JH−H = 7.4 Hz, 3H, 11-Me), 1.63
3
3
3
1 H, 1-CH), 6.63 (d, JH−H = 15.4 Hz, 1 H, 3-CH), 6.86 (dd,
(d, JH−H = 6.6 Hz, 3H, 1−Me), 2.01 (quint, JH−H = 7.4 Hz,
3JH−H = 15.5, 10.9 Hz, 1 H, 5-CH), 6.86−7.24 (m, 15 H, Ph).
13C{1H} NMR (100.5 MHz, C6D6, room temperature): δ
126.3, 126.9, 127.4, 128.0, 128.6 128.9, 129.1, 129.3, 129.4,
131.7, 132.0, 132.8, 136.8, 137.4, 138.3, 138.6, 141.9. MS (EI):
m/z 308 (M+). HRMS (APCI): C24H12 (308.42) m/z 308.1552
(M+), calcd for C24H20 308.1560.
3
2H, 8-CH2), 2.19 (q, JH−H = 7.4 Hz, 2H, 10-CH2), 5.37 (t,
3JH−H = 7.4 Hz, 1H, 7-CH), 5.57 (dq, 3JH−H = 15.0, 7.5 Hz, 1H,
3
2-CH), 6.12 (d, JH−H = 15.5 Hz, 1H, 5-CH), 6.14 (m, 1H, 3-
CH), 6.27 (dd, JH−H = 15.4, 10.3 Hz, 1H, 4-CH). 13C{1H}
3
NMR (100.5 MHz, C6D6, room temperature): δ 14.1, 14.5,
18.3, 20.1, 21.6, 126.6, 128.6, 133.1, 133.8, 134.5, 140.0. MS
(EI): m/z 150 (M+). HRMS (APCI): C11H18 (150.14) m/z
151.1485 [M + 1H]+, calcd for C11H18 151.1481.
Reaction of 3-Hexyne (3e) with 1-Phenyl-1,3-buta-
diene (3b) To Give (1E,3E,6E)-4eb.
Reaction of 3-Hexyne (2e) with Methyl 2,4-Hexadie-
noate (3d) To Give (2E,4E,6E)-4ed.
Using method A, the reaction of 3-hexyne (2e; 80.0 μL, 0.704
mmol) with 1-phenyl-1,3-butadiene (3b; 100.0 μL, 0.713
mmol) was catalyzed by 1 (23.3 mg, 0.0691 mmol) at room
temperature for 1 h. The crude product was directly purified by
flash chromatography using silica gel (hexane) to give a
colorless oil of (1E,3E,6E)-4eb (35.6 mg, 0.168 mmol). The
yield of 4eb was 24%. Using method B, the reaction of 3-
hexyne (2e; 24.0 μL, 0.211 mmol) with (E)-1-phenyl-1,3-
butadiene (30.0 μL, 0.214 mmol) was catalyzed by 1 at room
temperature for 30 min. On the basis of dibenzyl (11.3 mg,
0.0620 mmol) as an internal standard, (1E,3E,5E)-4eb was
Reaction of 3-hexyne (2e; 32.0 μL, 0.282 mmol) with methyl
hexa-2,4-dienoate (3d) in benzene-d6 (0.255 mmol/100 μL,
110 μL, 0.281 mmol) was catalyzed by 1 (9.6 mg, 0.029 mmol)
in C6D6 (710 μL) at 50 °C for 27 h. On the basis of dibenzyl
(13.7 mg, 0.0752 mmol) as an internal standard, the product
was determined by NMR and GLC/GC-MS. Yields:
(2E,4E,6E)-4ed, 17%; isomer, 1%. 1H NMR (400 MHz,
3
C6D6, room temperature): δ 0.85 (t, JH−H = 7.4 Hz, 3H, 8-
3
1
Me), 0.87 (t, JH−H = 7.4 Hz, 3H, 10-Me), 1.67 (s, 3H, 5-Me),
obtained in 82% yield along with the isomer in 10% yield. H
3
3
NMR (400 MHz, C6D6, room temperature): δ 0.92 (t, 3JH−H
=
1.94 (quint, JH−H = 7.4 Hz, 2H, 7-CH2), 2.12 (q, JH−H = 7.4
Hz, 2H, 9-CH2), 3.48 (s, 3 H, 1-CO2Me), 5.51 (t, 3JH−H = 7.48
Hz, 1H, 6-CH), 5.98 (d, 3JH−H = 14.9 Hz, 1H, 2-CH), 6.24 (d,
7.4 Hz, 3H, 8-CH3), 1.05 (t, 3JH−H = 7.4 Hz, 3H, 7′-CH3), 2.03
3
3
(quint, JH−H = 7.4 Hz, 2H, 7-CH2), 2.24 (q, JH−H = 7.5 Hz,
3JH−H = 11.4 Hz, 1H, 4-CH), 7.96 (dd, JH−H = 15.2, 12.0 Hz,
3
3
2H, 6′-CH2), 5.44 (t, JH−H = 7.4 Hz, 1H, 6-CH), 6.27 (d,
1H, 3-CH). MS (EI): m/z 208 (M+). This compound was only
characterized by spectroscopic methods.
3JH−H = 15.5 Hz, 1H, 4-CH), 6.39 (dd, JH−H = 15.5, 10.3 Hz,
3
3
1H, 3-CH), 6.44 (d, JH−H = 15.5 Hz, 1H, 1-CH), 6.84 (dd,
3JH−H = 15.5, 10.3 Hz, 1H, 2-CH), 7.04 (t, 3JH−H = 7.44 Hz, 1H,
p-Ph), 7.12−7.16 (2H, m-Ph, overlapped with resonances for
Reaction of Diphenylacetylene (2a) with 1-Phenyl-
[4,4-2H2]-1,3-butadiene (3b-d2) To Give (1E,3E,5E)-
[1,3-2H2]-4ab-d2.
3
C6D5H), 7.30 (d, JH−H = 7.48 Hz, 2H, o-Ph). 13C{1H} NMR
(100.5 MHz, C6D6, room temperature): δ 14.1, 14.4, 20.2, 21.8,
126.6, 126.8, 127.4, 128.9, 130.4, 131.6, 135.2, 137.4, 138.2,
140.2. MS (EI): m/z 212 (M+) HRMS (APCI): C16H20
(212.34) m/z 213.1642 [M + 1H]+, calcd for C16H21 213.1638.
Reaction of 3-Hexyne (2e) with trans-1,3-Pentadiene
(3c) To Give (2E,4E,6E)-4ec.
Reaction of 2a (44.5 mg, 0.250 mmol) with 3b-d2 (33.3 mg,
0.247 mmol; 83 atom % D) was catalyzed by 1 (2.45 mg,
0.00726 mmol) in benzene-d6 (600 μL) at room temperature
for 24 h to give (1Z,3E,5E)-4ab-d2. On the basis of
triphenylmethane (7.74 mg, 0.0317 mmol) as an internal
standard, the yield of (1Z,3E,5E)-4ab-d2 was estimated as 82%,
and the deuterium contents at C(1) and C(3) positions were
Using method A, the reaction of 3-hexyne (2e; 80.0 μL, 0.704
mmol) with trans-1,3-pentadiene (3c; 80.0 μL, 0.793 mmol)
was catalyzed by 1 (26.6 mg, 0.0790 mmol) at room
1
75 atom % D and 82 atom % D, respectively. H NMR (400
G
DOI: 10.1021/acs.organomet.6b00668
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
MHz, C6D6, room temperature): δ 6.07 (d, 3JH−H = 15.6 Hz, 1
Reaction of 1,3-Bis(1-pentynyl)benzene (2i) with
M e t h yl P e n t a- 2 , 4 -d i e n o at e ( 3 a ) T o G iv e
(1E,1′E,3E,3′E,5E,5′E)-4ia.
3
H, 6-CH), 6.17 (d, JH−H = 10.9 Hz, 1 H, 4-CH), 6.86 (dd,
3JH−H = 15.6, 10.9 Hz, 1 H, 5-CH), 6.83−7.24 (m, 15 H, Ph).
2H NMR (61.4 MHz, C6H6, room temperature): δ 6.6 (br, 1-
CD and 3-CD).
Reaction of 1,4-Bis(1-pentynyl)benzene (2h) with
M e t h y l P e n t a - 2 , 4 - d ienoate (3a) To Give
(1E,1′E,3E,3′E,5E,5′E)-4ha.
Reaction of 2i (98.5 mg, 0.468 mmol) with 3a (135 μL, 1.17
mmol) catalyzed by 1 (15.89 mg, 0.04710 mmol) at room
temperature for 20 h gave a reddish brown solution. The
reaction system was quenched by bubbling of air. After removal
of solvent, the resulting black oil was purified by silica gel
chromatography (AcOEt/hexane 1/5). Removal of the solvent
of a fraction gave a lemon-yellow oil of 4ia as a yellow oil
Reaction of 2h (105.7 mg, 0.503 mmol) with 3a (150 μL, 1.30
mmol) catalyzed by 1 (17.0 mg, 0.0504 mmol) gave a light
yellow-brown precipitate within 4 days at room temperature,
which was separated by a cannula tube and washed with hexane
to give analytically pure 4ha (133.1 mg, 0.307 mmol) in 61%
yield. 1H NMR (400 MHz, CDCl3, room temperature): δ 1.02
1
(198.0 mg, 0.456 mmol) in 97% yield. H NMR (400 MHz,
3
CDCl3, room temperature): δ 0.97 (t, JH−H = 7.2 Hz, 6H,
−CH2CH2Me), 1.54 (m, partly overlapped with water in C6D6,
−CH2CH2Me), 2.44 (m, 4H, -CH2CH2Me), 3.74 (s, 6H,
CO2Me), 5.92 (d, 3JH−H = 15.4 Hz, 2H, 6-CH), 6.42 (dd, 3JH−H
= 15.2, 11.2 Hz, 2H, 4-CH), 6.61 (s, 2H, 1-CH), 6.64 (d, 3JH−H
= 15.5 Hz, 2H, 3-CH), 7.19 (d, 3JH−H = 6.3 Hz, 2H, aromatic),
3
3
(t, JH−H = 7.5 Hz, 6H, −CH2CH2Me), 1.61 (sext, JH−H = 7.4
Hz, 4H, −CH2CH2Me), 2.48 (m, 4H, -CH2CH2Me), 3.74 (s,
6H, CO2Me), 5.92 (d, 3JH−H = 15.5 Hz, 2H, CH−), 6.42 (dd,
3JH−H = 15.2, 11.2 Hz, 2H, CH−), 6.59 (s, 2H, ArCH),
6.64 (d, 3JH−H = 15.5 Hz, 2H, CH−), 7.30 (s, 4H, aromatic),
3
7.20 (s, 1H, aromatic), 7.38 (t, JH−H = 6,3 Hz, 1H, aromatic),
3
7.40 (dd, JH−H = 15.5, 11.2 Hz, 2H, 5-CH). This compound
3
7.39 (dd, JH−H = 10.9, 15.5 Hz, 2H, CH−). 13C{1H} NMR
was only characterized by spectroscopic methods.
Synthesis of Ru(η4-methyl penta-2,4-dienoate)(η4-1,5-
COD)(NCMe) (5a).
(100 MHz, CDCl3, room temperature): δ 14.39, 22.37, 29.49,
51.53, 119.93, 125.62, 129.10, 135.10, 136.10, 140.61, 145.32,
145.68, 167.63. Mp (air): 156.1−157.5 °C. λmax (CH2Cl2, 1.10
× 10−5 M): 384 nm; ε (384 nm) 6.62 × 104 L mol−1 cm−1.
Anal. Calcd for C20H34O4 (424.58): C, 77.39; H, 7.89. Found:
C, 77.73; H, 8.31.
Preparation of 1,3-Bis(1-pentynyl)benzene (2i).
According to a previous report,15 complex 5a was prepared as
follows. Ru(η6-naphthalene)(η4-1,5-COD) (1; 146.4 mg,
0.4339 mmol) was dissolved in acetonitrile (5 mL), and then
(E)-methyl penta-2,4-dienoate (3a; 50.0 μL, 0.430 mmol) was
added by a hypodermic syringe. After 5 h of reaction at room
temperature, all volatile materials were removed under reduced
pressure and the resulting yellow oil was crystallized from cold
hexane/Et2O to give yellow crystals of 5a (110.9 mg, 0.3060
mmol) in 71% yield. 1H NMR (400 MHz, C6D6, room
temperature): δ 0.65−0.67 (d, 3JH−H = 8.6 Hz, 1H, 5-endo-CH),
0.74 (s, 3H, NCMe), 1.60−1.62 (d, 3JH−H = 7.4 Hz, 1H, 2-endo-
CH), 1.69−1.70 (d, 3JH−H = 6.3 Hz, 1H, 5-exo-CH), 1.91−2.03
(m, 3H, CH2 in COD), 2.14−2.21 (m, 1H, CH2 in COD),
2.29−2.32 (m, 1H, CH2 in COD), 2.39−2.43 (m, 1H, CH2 in
COD), 2.50−2.54 (m, 1H, CH2 in COD), 2.61−2.66 (m, 1H,
CH2 in COD), 2.86−2.89 (m, 1H, CH in COD), 3.36−3.40
(m, 1H, CH in COD), 3.46 (s, 3H, CO2Me), 4.54−4.56 (m,
Similar to the case for 1,4-bis(1-pentynyl)benzene (2h),22 2i
was prepared as follows. Reaction of 1,3-diiodobenzene (996.9
mg, 3.022 mmol) with 1-pentyne (720 μL, 7.30 mmol) in the
presence of CuI (120.8 mg, 0.6341 mmol) and PdCl2(PPh3)2
(90.6 mg, 0.129 mmol) in THF (31 mL) and NEt3 (31 mL) at
room tempearture in the dark for 13 h resulted in deposition of
a white powder. After addition of saturated NH4Cl/H2O, the
organic layer was separated and dried over MgSO4 and
evaporated to give an umber oil. After silica gel column
chromatography using hexane, 2i was obtained as an umber oil
1
(449.2 mg, 2.136 mmol) in 71% yield. H NMR (400 MHz,
CDCl3, room temperature): δ 1.02 (t, 3JH−H = 7.2 Hz, 6H, Me),
3
3
1.60 (sext, JH−H = 7.2 Hz, 4H, CH2), 2.35 (t, JH−H = 7.2 Hz,
3
5
4H, CH2), 7.16 (AMM′N, JH−H = 5.75 Hz, JH−H = 0.30 Hz,
1H, C6H4), 7.26 (AMM′N, 3JH−H = 5.75 Hz, 4JH−H = −0.86 Hz,
2H, C6H4), 7.42 (AMM′N, 4JH−H = −0.86 Hz, 5JH−H = 0.30 Hz,
1H, C6H4). This compound was used for further reaction
without elemental analysis.
3
1H, CH in COD), 4.87−4.92 (br q, J = 7.4 Hz, 1H, 4-CH),
3
6.18−6.21 (dd, JH−H = 7.4, 5.2 Hz, 1H, 3-CH). This
compound was only characterized by spectroscopic methods.
H
DOI: 10.1021/acs.organomet.6b00668
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Article
Reaction of Ru(η4-methyl penta-2,4-dienoate)(η4-1,5-
COD)(NCMe) (5a) with Diphenylacetylene (2a) To Give
6aa.
an independent reaction, we have confirmed the molecular
structure of 7a by an X-ray structure analysis.
Reaction of Ru(η4-methyl penta-2,4-dienoate)(η4-1,5-
COD)(NCMe) (5a) with 3-Hexyne (2e) and Methyl Penta-
2,4-dienoate (3a). In an NMR tube was placed 5a (6.8 mg,
0.019 mmol), and benzene-d6 was introduced into the tube by
vacuum distillation. 2e (2.2 μL, 0.019 mmol) was added to the
solution by a hypodermic syringe. After addition of mesitylene
(2.6 μL, 0.019 mmol) as an internal standard at room
1
1
temperature, H NMR was measured. The H NMR spectrum
suggested formation of a mixture involving the triene complex
(48%) and 4ea (36%), and subsequent addition of 3a (2.4 μL,
0.020 mmol) produced (2E,4E,6E)-4ea in 80% yield with
recovery of 5a in 63% yield.
Ru(η4-methyl penta-2,4-dienoate)(η4-1,5-COD)(NCMe) (5a;
19.1 mg, 0.0527 mmol) was treated with 2a (11.6 mg, 0.0651
mmol) in benzene at room temperature for 1 h. After removal
of volatile materials, the residue was recrystallized from cold
benzene/hexane to give pale yellow microcrystals of 6aa (14.7
Reaction of Ru(η4-2,3-dimethylbutadiene)(η4-1,5-
COD)(NCMe) (5e) with Diphenylacetylene (2a) To Give
6ae.
1
mg, 0.0272 mmol) in 52% yield. H NMR (400 MHz, C6D6,
room temperature) δ 1.10−1.35 (m, 2H, COD), 1.57−1.70 (m,
1H, COD), 2.01−2.10 (m, 2H, COD), 1.95−2.05 (m, 1H,
COD), 2.20−2.30 (m, 1H, COD), 2.55−2.60 (m, 1H, COD),
2.60−2.70 (m, 1H, COD), 2.74 (t, 3JH−H = 4.6 Hz, 1H, 4-CH),
2.93 (d, 3JH−H = 4.6 Hz, 1H, 5-CH), 2.98−3.12 (m, 1H, COD),
3.59 (s, 3H, −CO2Me), 3.78−3.90 (m, 2H, COD), 4.24 (d,
3JH−H = 8.6 Hz, 1H, 2-CH), 4.35−4.55 (m, 1H, COD), 5.16 (s,
1H, 7-CH), 5.24 (dd, 3JH−H = 8.6, 5.2 Hz, 1H, 3-CH), 7.4−6.9
(m, Ph, 10H). 13C{1H} NMR (100 MHz, C6D6, room
temperature): δ 25.69 (CH2 in COD), 26.69 (CH2 in COD),
34.24 (CH2 in COD), 38.89 (CH2 in COD), 39.19 (2-CH),
50.86 (−CO2Me), 51.31 (7-CH), 73.55 (CH in COD), 78.12
(CH in COD), 80.99 (CH in COD), 81.56 (4-CH), 85.30 (5-
CH), 88.76 (CH in COD), 106.83 (3-CH), 112.83 (6-C),
124.94 (CH in Ph), 126.45 (CH in Ph), 127.80 (CH in Ph),
128.29 (CH in Ph), 128.73 (CH in Ph), 128.90 (CH in Ph),
138.23 (8-C), 146.08 (9-C), 174.83 (1-C). This compound was
only characterized by spectroscopic methods.
Ru(η4-2,3-dimethylbutadiene)(η4-1,5-COD)(NCMe) (5e;15
101.1 mg, 0.3041 mmol) was treated with 2a (54.4 mg, 0.305
mmol) in benzene at room temperature for 22 h. After removal
of volatile materials, the residue was recrystallized from cold
Et2O/hexane to give yellow microcrystals of 6ae (79.1 mg,
1
0.155 mmol) in 51% yield. H NMR (400 MHz, C6D6, room
temperature) δ 0.91−0.98 (m, 1H, COD), 1.02 (s, 3H, 3−Me),
1.18−1.32 (m, 2H, COD), 1.44 (s, 3H, 2−Me), 1.47−1.54 (m,
1H, COD), 1.84−1.92 (m, 2H, COD), 2.45−2.50 (m, 2H,
COD), 2.52 (s, 1H, 1-CH), 2.54−2.60 (m, 1H, COD), 2.67 (s,
1H, 6-CH), 2.68−2.75 (m, 1H, COD), 2.86−2.92 (m, 1H,
COD), 3.51 (s, 1H, 4-CH), 3.73−3.77 (m, 1H, COD), 4.06−
4.09 (m, 1H, COD), 4.79 (s, 1H, 1-CH), 7.00−7.19 (m, 10H,
Ph). 13C{1H} NMR (100.5 MHz, C6D6, room temperature): δ
12.6, 18.8, 25.2, 26.4, 32.7, 38.1, 40.0, 53.0, 68.0, 68.8, 75.7,
79.6, 82.6, 85.0, 114.5, 115.9, 123.9, 127−130 (multiple
signals), 138.5, 143.6. Anal. Calcd for C28H32Ru (469.18): C,
71.61; H, 6.87. Found: C, 71.28; H, 7.43.
Reaction of 6aa with Methyl Penta-2,4-Dienoate (3a)
To Give 7a.
Reaction of 6ae with 2,3-Dimethylbutadiene (3).
Complex 6ea (5.83 mg, 0.0124 mmol) and triphenylmethane
(4.90 mg, 0.0220 mmol) as an internal standard were placed in
an NMR tube. Then, benzene-d6 (0.6 mL) was transferred into
the NMR tube by vacuum distillation. Compound 3e (3.4 μL,
0.0301 mmol) was added to the solution. However, no reaction
was observed after 16 h of reaction at room temperature. Then,
3a (3.4 μL, 0.0292 mmol) was added but no reaction occurred
after 8 h at room temperature.
X-ray Analysis. Single crystals of 7a suitable for X-ray
analysis were obtained from a benzene solution. A single crystal
was selected using a polarized microscope was mounted on a
glass capillary by use of Paratone-N oil. A Rigaku AFC-7R-
Mercury II diffractometer with graphite-monochromated Mo
Kα radiation (λ = 0.71075 Å) was used for data collection at
200 K. The collected data were solved by direct methods and
refined by a full-matrix least-squares procedure using the
CrystalStructure program (version 4.2).24,25 All hydrogen
atoms were treated as a riding model. The optimized structure
is depicted in Figure 1 using the POV-Ray program (version
3.6.2).26
Treatment of 6aa (15.7 mg, 0.0272 mmol) with 2 equiv of 3a
and triphenylmethane as an internal standard at room
temperature for 2 h gave liberation of 4aa in 91% yield with
concomitant formation of the bis(η3-allylic)ruthenium(II)
complex 7a in 55% yield. Alternatively, 7aa was directly
prepared by the reaction of 6aa with 3a. Treatment of 6aa (7.1
mg, 0.020 mmol) with 3a (2.4 μL, 0.021 mmol) in the presence
of triphenylmethane as an internal standard (7.8 mg, 0.0319
mmol) at room tempearture for 3 days gave supine,prone-7a in
1
77% yield. H NMR (400 MHz, C6D6, room temperature): δ
0.58−0.64 (m, 2H, 5-CH), 1.44−1.59 (m, 2H, CH2 in COD),
1.67−1.72 (m, 2H, CH2 in COD), 1.82−1.88 (m, 2H, CH2 in
COD), 1.83−1.85 (m, 1H, 4-CH), 2.07−2.14 (m, 1H, CH2 in
COD), 2.52−2.59 (m, 1H, CH2 in COD), 2.97−2.99 (d, 3JH−H
= 9.7 Hz, 1H, 9-CH), 3.36 (s, 3H, 1 or 10−Me), 3.38−3.49 (m,
3
1H, CH in COD), 3.50−3.52 (d, JH−H = 9.8 Hz, 1H, 2-CH),
3.57−3.62 (m, 1H, CH in COD), 3.65 (s, 3H, 10- or 1−Me),
3.78−3.82 (m, 1H, CH in COD), 4.21−4.26 (m, 1H, CH in
3
COD), 4.77−4.82 (t, JH−H = 9.7 Hz, 1H, 3-CH), 4.82−4.86
3
(m, 1H, 7-CH), 5.32−5.35 (t, JH−H = 9.7 Hz, 1H, 8-CH). By
I
DOI: 10.1021/acs.organomet.6b00668
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other atoms.27 The effect of benzene as a solvent was included
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(PCM) using the integral equation formalism variant
(IEFPCM).28 The optimized molecular structures were verified
by vibrational analysis. Intrinsic reaction coordinate (IRC)
calculations29,30 were carried out to check whether or not the
transition state leads to the reactant and the product. Relative
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ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.6b00668.
■
S
(16) Hirano, M.; Sakate, Y.; Komine, N.; Komiya, S.; Wang, X.-Q.;
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NMR and physical data of new compounds and X-ray
data for 7a and preliminary X-ray structures of 4ca,ha
(PDF)
DFT calculations for A−E and TS1−TS3 (PDF)
Crystallographic data for 7a (CIF)
(17) We tentatively found a possible transition state having a single
imaginary vibration for the conversion of D to E (TS4; −10.98 kcal
mol−1: ΔΔG⧧ = 8.48 kcal mol−1). A similar transition state was also
proposed for Fe(η4-1,3,5-hexatriene)(CO)3: Gonzal
́
ez-Blanco, O.;
̀
Branchadell, V. Organometallics 2000, 19, 4477−4482.
Cartesian coordinates for A−E and TS1−TS3 (XYZ)
(18) Bennett, M. A.; Neumann, H.; Thomas, M.; Wang, X.-Q.;
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3245.
AUTHOR INFORMATION
Corresponding Author
*E-mail for M.H.: hrc@cc.tuat.ac.jp.
■
(19) Kottas, G. S.; Brotin, T.; Schwab, P. F. H.; Gala, K.; Havlas, Z.;
Kirby, J. P.; Miller, J. R.; Michl, J. Organometallics 2014, 33, 3251−
3264.
(20) Wettach, H.; Jester, S. S.; Colsmann, A.; Lemmer, U.; Rehmann,
ORCID
N.; Meerholz, K.; Hoger, S. Synth. Met. 2010, 160, 691−700.
̈
Masafumi Hirano: 0000-0001-7835-1044
Notes
The authors declare no competing financial interest.
(21) Ravera, M.; D’Amato, R.; Guerri, A. J. Organomet. Chem. 2005,
690, 2376−2380.
(22) Liu, J.; Zhang, S.; Zhang, W.-X.; Xi, Z. Organometallics 2009, 28,
413−417.
ACKNOWLEDGMENTS
(23) (a) Yin, G.; Wu, Y.; Liu, G. J. Am. Chem. Soc. 2010, 132, 11978−
11987. (b) Zheng, M.; Huang, L.; Wu, W.; Jiang, H. Org. Lett. 2013,
15, 1838−1841.
■
We are grateful to T. Ueda (TUAT) for preparation of 5a and
7a and S. Watanabe (TUAT) for preparation of 6ae. We also
thank Prof. K. Noguchi (TUAT) for HRMS analyses. This
work was financially supported by the Japan Science and
Technology Agency (JST) ACT-C. A part of this work was
supported by a Grant-in-Aid for Scientific Research on
Innovative Areas, “3D Active-Site Science” 26105003.
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