Ruthenium- and Rhodium-Catalyzed Ring-Opening Coupling Reactions of Cyclopropenones with Alkenes or Alkynes

Article abstract of DOI:10.1055/s-0037-1609339

Ru ₃ (CO) ₁₂ -catalyzed divergent ring-opening coupling reactions of a cyclopropenone with methyl acrylate (an electron-deficient alkene) are developed. Under an argon atmosphere, a decarbonylative linear codimer is obtained, while cyclopentenones are obtained under carbon monoxide (20 atm) without decarbonylation. While ruthenium complexes show no catalytic activity for the ring-opening cocyclization of cyclopropenones with ethylene (20 atm) or bicyclo[2.2.1]hept-2-ene (2-norbornene), rhodium complexes, especially [RhCl(η ⁴ -1,5-cod)] ₂, show high catalytic activity for the desired cocyclization reactions to give the corresponding cyclopentenones in high yields and selectivities. In addition, [RhCl(η ⁴ -1,5-cod)] ₂ realizes the catalytic ring-opening cocyclization of cyclopropenones with internal alkynes to give the corresponding cyclopentadienones. In all these reactions, ruthena- or rhodacyclobutenones are considered to be key intermediates, generated by strain-driven oxidative addition of a cyclopropenone C-C bond to an active ruthenium or rhodium species.

Full text of DOI:10.1055/s-0037-1609339

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© Georg Thieme Verlag Stuttgart · New York
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Ruthenium- and Rhodium-Catalyzed Ring-Opening Coupling
Reactions of Cyclopropenones with Alkenes or Alkynes
Teruyuki Kondo*a
First Ru-catalyzed divergent ring-opening coupling reactions of a cyclopropenone with an alkene
Ryosuke Taniguchia
Yu Kimurab
Ph
Ph
Ru3(CO)12
57%
(4Z/4E = >95:<5)
100 °C, 20 h
under Ar
Ph
a Department of Energy and Hydrocarbon Chemistry, Graduate
School of Engineering, Kyoto University, Nishikyo-ku, Kyoto
615-8510, Japan
CO2Me
O
+
O
CO2Me
3.0 mL
Ru3(CO)12
Ph
Ph
1.0 mmol
47%
teruyuki@scl.kyoto-u.ac.jp
(solvent)
160 °C, 20 h
under CO (20 atm)
b Research and Educational Unit of Leaders for Integrated Medical
Systems, Center for the Promotion of Interdisciplinary Education
and Research, Kyoto University, Nishikyo-ku, Kyoto 615-8510,
Japan
Ph
CO2Me
Rh-catalyzed synthesis of cyclopentenones and cyclopentadienones via cleavage of a C–C bond
O
R1
Ph
Ph
Ph
[RhCl(h4-1,5-cod)]2
R1
up to 61%
O
+
1,4-dioxane (3.0 mL)
100 °C, 20 h
under Ar (without CO)
Ph
R2
R2
1.5 mmol 1.0 mmol
Received: 20.01.2018
Accepted after revision: 18.02.2018
Published online: 01.03.2018
series of Rh(I)- as well as Pd(0)- and Ni(0)-catalyzed reac-
tions cleaving a C–C bond in cyclobutanones, involving the
intramolecular interception of metallacyclopentanone in-
termediates by tethered C–C unsaturated bonds.5,6 More re-
cently, Cramer reported the regiodivergent ring-opening of
3-(2-alkanoylphenyl)cyclobutanones by the appropriate
choice of Lewis acid catalysts, Cu(OTf)2 or SnCl4, to give the
corresponding indenylacetic acids and benzoxabicy-
clo[3.2.1]octane-3-ones in high yields, respectively.7 Uemu-
ra and Nishimura reported a similar palladium-catalyzed β-
carbon elimination8 from tert-cyclobutanols. An enantiose-
lective version of this process was also developed by
Nishimura9 and Cramer,10 independently.
We have already developed a series of ruthenium- and
rhodium-catalyzed strain-driven reactions cleaving a C–C
bond in cyclopropenones,11a,12 cyclobutenones,11b,c cy-
clobutenediones,11d and bicyclo[2.2.1]hepta-2,5-diene (2,5-
norbornadiene),11e followed by the reconstruction of novel
and valuable functional organic molecules. As a continua-
tion of our study on the catalytic cleavage of a C–C bond in
cyclopropenones, we succeeded in developing novel ruthe-
nium- and rhodium-catalyzed ring-opening coupling reac-
tions of cyclopropenones with alkenes or alkynes through
the formation of ruthena- or rhodacyclic intermediates.
First, the reaction of 2,3-diphenylcycloprop-2-en-1-one
(1) with methyl acrylate (2) (solvent) was examined in the
presence of a catalytic amount of Ru3(CO)12 at 100 °C for 20
hours under an argon atmosphere to give the decarbonylat-
ed linear codimer, methyl (2E,4Z)-4,5-diphenylpenta-2,4-
dienoate (3), in 57% yield with high stereoselectivity
(4Z/4E = >95:<5) (the upper reaction in Scheme 1).
DOI: 10.1055/s-0037-1609339; Art ID: st-2018-u0042-c
Abstract Ru3(CO)12-catalyzed divergent ring-opening coupling reac-
tions of a cyclopropenone with methyl acrylate (an electron-deficient
alkene) are developed. Under an argon atmosphere, a decarbonylative
linear codimer is obtained, while cyclopentenones are obtained under
carbon monoxide (20 atm) without decarbonylation. While ruthenium
complexes show no catalytic activity for the ring-opening cocyclization
of cyclopropenones with ethylene (20 atm) or bicyclo[2.2.1]hept-2-ene
(2-norbornene), rhodium complexes, especially [RhCl(η4-1,5-cod)]2,
show high catalytic activity for the desired cocyclization reactions to
give the corresponding cyclopentenones in high yields and selectivities.
In addition, [RhCl(η4-1,5-cod)]2 realizes the catalytic ring-opening co-
cyclization of cyclopropenones with internal alkynes to give the corre-
sponding cyclopentadienones. In all these reactions, ruthena- or rhoda-
cyclobutenones are considered to be key intermediates, generated by
strain-driven oxidative addition of a cyclopropenone C–C bond to an
active ruthenium or rhodium species.
Key words C–C bond cleavage, cyclopropenone, ruthenium, rhodium,
cyclopentenone, cyclopentadienone, metallacyclic intermediate
The development of catalytic cleavage of a C–C bond un-
der mild reaction conditions is one of the most important,
attractive, and challenging subjects in atom-economical
organic, organometallic, and industrial chemistry, because
novel functional organic molecules that cannot be obtained
by the simple combination of traditional synthetic methods
can be synthesized in one step. Over the last three decades,
there have been significant advances in homogeneous tran-
sition-metal-complex-catalyzed cleavage and reconstruc-
tion of the C–C bond for the synthesis of fine chemicals.1,2
In particular, C–C bond cleavage of strained cyclic mole-
cules is considerably facilitated by the release of ring-strain
through metal insertion.3 Ito and Murakami reported the
first C–C bond cleavage of cyclobutanones with a Rh(I) cata-
lyst in 1994.4 Murakami and co-workers then developed a
In sharp contrast, the same reaction of 1 with 2 gave a
single regioisomeric cyclopentenone, methyl 4-oxo-2,3-di-
phenylcyclopent-2-ene-1-carboxylate (4), in 47% yield
when the reaction was carried out with the same Ru3(CO)12
catalyst in toluene at 160 °C for 20 hours under carbon
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

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T. Kondo et al.
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monoxide (20 atm) (the lower reaction in Scheme 1). Exter-
nal carbon monoxide could suppress the decarbonylation of
1 to 1,2-diphenylethyne and serve as an effective π-acidic
ligand to promote reductive elimination to give 4.13
Ru3(CO)12
Ph
Ph
(0.066 mmol)
100 °C, 20 h
under Ar (1 atm)
CO2Me
Ph
Ph
3 57%
(4Z/4E = >95:<5)
+
O
CO2Me
O
Ru3(CO)12
Ph
1
2
Figure 1 X-ray crystal structure of compound 4 (CCDC 1826244)
(0.066 mmol)
1.0 mmol
3.0 mL
160 °C, 20 h
under CO (20 atm)
(in an autoclave)
(solvent)
Ph
CO2Me
4, 47%
It is well known that an electron-withdrawing group at
an α-position to a metal stabilizes many metallacycles, and
the insertion of methyl acrylate (2) into a ruthenacyclo-
butenone stabilized by a phenyl group may occur to give
two regioisomeric ruthenacyclohexenones. Under carbon
monoxide, replacement of the strongly coordinated carbon
monoxide ligand is required, and an alkene 2 should coordi-
nate and insert into a ruthenacyclobutenone in a less-hin-
dered direction to give another regioisomeric ruthena-
cyclohexanone, which gives an unusual cyclopentenone 4
with high selectivity in place of methyl 2-oxo-3,4-diphenyl-
cyclopent-3-ene-1-carboxylate (4′).
To obtain other cyclopentenones, 1 was treated with a
catalytic amount of several ruthenium complexes in 1,4-di-
oxane at 100 °C for 20 hours under ethylene (5) (40 atm).
However, no reaction occurred with ruthenium catalysts
such as Ru3(CO)12, Ru(η4-1,5-cod)(η6-1,3,5-cot) [1,3,5-cyclo-
octatriene], and [RuCl2(CO)3]2.
Next, the catalytic activities of several rhodium com-
plexes were investigated. As a result, [RhCl(η4-1,5-cod)]2
(1,5-cod = 1,5-cyclooctadiene) showed the highest catalytic
activity giving 2,3-diphenylcyclopent-2-en-1-one (6) in
82% yield (Scheme 3, a); [RhCl(CO)2]2: 25%, [RhCl(η2-
C2H4)2]2: 44%, [RhCl(η4-2,5-norbornadiene)]2: 31%. Bi-
cyclo[2.2.1]hept-2-ene (2-norbornene) (7) could also be used
in the present reaction to give a tricyclic cyclopentenone,
Scheme 1 Ru3(CO)12-catalyzed divergent ring-opening coupling reac-
tions of 2,3-diphenylcycloprop-2-en-1-one (1) with methyl acrylate (2)
The present Ru3(CO)12-catalyzed divergent reactions can
be explained by assuming the same ruthenacyclobutenone
intermediate, generated by the oxidative addition of cyclo-
propenone 1 to an active ruthenium species (Scheme 2).14
Subsequent insertion of an electron-deficient alkene 2 oc-
curred to give two regioisomeric ruthenacyclohexenone in-
termediates depending on the reaction conditions.15 Under
an argon atmosphere, the usual insertion of 2 would occur
to give a ruthenacyclohexenone bearing a methoxycarbonyl
group at an α-position with respect to ruthenium. Decarbo-
nylation of the ruthenacyclohexenone proceeded predomi-
nantly prior to reductive elimination, followed by β-hydro-
gen elimination/reductive elimination to give a linear codi-
mer 3. In sharp contrast, under carbon monoxide (20 atm),
the regioisomeric ruthenacyclohexenone bearing a me-
thoxycarbonyl group at a β-position with respect to ruthe-
nium formed, and subsequent reductive elimination gives
an unusual cyclopentenone 4 without decarbonylation. The
structure of 4 was confirmed by single-crystal X-ray struc-
ture determination (Figure 1).
H
Ph
Ph
O
Ph
Ph
CO
[Ru]
[Ru]
H
[Ru]
Ph
[Ru]
Ph
E
2
E
Ph
E
E
3
Ph
E
H
H
CO
Ph
Ph
Ph
Ph
O
[Ru]
O
[Ru]
2
E
CO
1
O
E
Ph
O
[Ru]
Ph
Ph
[Ru]
Ph
(CO)
E
4
Scheme 2 A possible mechanism
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

C
T. Kondo et al.
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sult clearly suggests that the successful formation of rhoda-
cyclobutenones requires the use of cyclopropenones as
starting materials.
(a)
[RhCl(η4-1,5-cod)]2
(0.10 mmol)
O
Ph
Ph
Ph
+
O
1,4-dioxane (3.0 mL)
100 °C, 20 h
(in an autoclave)
Ph
1.0 mmol
1
5
6, 82%
40 atm
O
(b)
[RhCl(η4-1,5-cod)]2 Ph
Ph
(0.10 mmol)
+
O
1,4-dioxane (3.0 mL)
100 °C, 20 h
Ph
H
Ph
H
under Ar
1
7
8, 61%
(exo >99%)
1.0 mmol
3.0 mmol
Scheme 3 [RhCl(η4-1,5-cod)]2-catalyzed synthesis of cyclopentenones
exo-2,3-diphenyl-3a,4,5,6,7,7a-hexahydro-1H-4,7-methano-
inden-1-one (8), in 61% yield with high exo selectivity
(>99%) (Scheme 3, b). However, the reaction of 1 with bi-
cyclo[2.2.1]hepta-2,5-diene (2,5-norbornadiene) (9) gave
5,6-diphenyl-1,2,3,3a,4,6a-hexahydro-1,2,4-(epimethane-
triyl)pentalene (10) in 47% yield in place of the desired tri-
cyclic cyclopentenone 10′; compound 10 was obtained by a
formal cycloaddition reaction of 1,4-diene 9 with 1,2-di-
phenylethyne derived from the decarbonylation of
(Scheme 4).
1
[RhCl(η4-1,5-cod)]2
Ph
(0.10 mmol)
Figure 2 The effect of both the ethylene pressure (at 100 °C for 20 h)
and the reaction temperature (under 40 atm of ethylene for 20 h)
+
O
1,4-dioxane (3.0 mL)
100 °C, 20 h
Ph
1.0 mmol
Ph
Ph
under Ar
1
9
10, 47%
3.0 mmol
Next, the reactions of 1 with symmetrically substituted
internal alkynes such as oct-4-yne (11a) and dec-5-yne
(11b) were carried out in the presence of a catalytic
amount of [RhCl(η4-1,5-cod)]2 in 1,4-dioxane at 100 °C for
20 hours under an argon atmosphere, which gave the ex-
pected cyclopentadienones, 2,3-diphenyl-4,5-dipropylcy-
clopenta-2,4-dien-1-one (12a) in 61% yield and 2,3-di-
butyl-4,5-diphenylcyclopenta-2,4-dien-1-one (12b) in 55%
yield, respectively (Scheme 5).
Scheme 4 The reaction of 1 with bicyclo[2.2.1]hepta-2,5-diene (2,5-
norbornadiene) (9)
To optimize the reaction conditions for the synthesis of
6, the effect of the solvent was examined: the present reac-
tion proceeded smoothly in toluene (6, 85%), THF (6, 83%),
1,4-dioxane (6, 82%), and N,N-dimethylacetamide (6, 67%).
Among the solvents examined, acetonitrile gave the best re-
sults, and 6 was obtained in 92% yield. However, triethyl-
amine (6, 17% yield) and pyridine (6, trace) were unsuitable
solvents, probably due to their high ability to coordinate to
an active rhodium species.
R1
O
[RhCl(η4-1,5-cod)]2
(0.10 mmol)
Ph
Ph
+
O
R1
1,4-dioxane (3.0 mL)
100 °C, 20 h
R2
Ph
Ph
1.5 mmol
R2
under Ar
1
11
1.0 mmol
The effects of both the ethylene pressure and the reac-
tion temperature were examined in acetonitrile, and the re-
sults are shown in Figure 2. Product 6 was obtained in over
90% yield under an ethylene pressure over 40 atmospheres
at a reaction temperature from 60 to 100 °C. Consequently,
6 was obtained in the best yield of 94% by the [RhCl(η4-1,5-
cod)]2-catalyzed ring-opening coupling reaction of 1 with 5
(50 atm) in acetonitrile at 100 °C for 20 hours. In addition, 6
was not obtained from the reaction of 1,2-diphenylethyne,
ethylene, and carbon monoxide (40 atm) with [RhCl(η4-1,5-
cod)]2 catalyst under the above reaction conditions. This re-
11a: R1 = R2 = n-C3H7
11b: R1 = R2 = n-C4H9
11c: R1 = Ph, R2 = COCH3
11d: R1 = Ph, R2 = CO2CH3
12a: 61%
12b: 55%
12c: 45%
12d: 41%
Scheme 5 [RhCl(η4-1,5-cod)]2-catalyzed synthesis of cyclopenta-
dienones
Unsymmetrically substituted alkynes such as 4-phenyl-
but-3-yn-2-one (11c) and methyl 3-phenylpropiolate (11d)
could be used in this reaction, and single regioisomeric cy-
clopentadienones, 3-acetyl-2,4,5-triphenylcyclopenta-2,4-
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

D
T. Kondo et al.
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dien-1-one (12c) and methyl 3-oxo-2,4,5-triphenylcyclo-
penta-1,4-diene-1-carboxylate (12d), were obtained in re-
spective yields of 45% and 41%, while no reaction occurred
with 1,2-diphenylethyne (11e), dimethyl but-2-ynedioate
(11f), and ethynylbenzene (11g).
Two isomeric products were obtained from the reaction
of 1 with prop-1-yn-1-ylbenzene (11h). The single-crystal
X-ray structure determination clearly showed that the two
isomeric products were the expected cyclopentadienone,
3-methyl-2,4,5-triphenylcyclopenta-2,4-dien-1-one (12h)
(23% yield), and the unexpected cyclopentenone, 4-methy-
lene-2,3,5-triphenylcyclopent-2-en-1-one (12h′) (20% yield),
respectively (Scheme 6).16
In addition, treatment of the isolated compound 12h
with [RhCl(η4-1,5-cod)]2 catalyst in 1,4-dioxane at 100 °C
for 20 hours gave 12h′ in 42% yield (conversion of 12h, 57%)
(Scheme 7). Accordingly, a possible mechanism for this
isomerization is illustrated in Scheme 8. Coordination of
12h to an active rhodium species, followed by activation of
a C–H bond of the methyl group by rhodium proceeds to
give an (η3-allyl)rhodium complex, and subsequent reduc-
tive elimination gives isomeric methylenecyclopentenone
12h′. Nishinaga and co-workers reported a similar isomeri-
zation of cyclopentadienones giving methylenecyclopen-
tenones under basic reaction conditions.17
O
[RhCl(η4-1,5-cod)]2
(0.10 mmol)
O
Ph
Ph
Ph
Ph
Ph
O
O
[RhCl(η4-1,5-cod)]2
(0.10 mmol)
Ph
Ph
Ph
Ph
Ph
Ph
Ph
1,4-dioxane (3.0 mL)
100 °C, 20 h
+
O
Ph
Ph
+
1,4-dioxane (3.0 mL)
100 °C, 20 h
under Ar
Ph
under Ar
12h
12h', 42%
1
11h
1.0 mmol
1.5 mmol
12h, 23%
12h', 20%
(57% conversion)
Scheme 6 [RhCl(η4-1,5-cod)]2-catalyzed reaction of 1 with prop-1-yn-
1-ylbenzene (11h)
Scheme 7 [RhCl(η4-1,5-cod)]2-catalyzed isomerization of 12h into
12h′
O
O
O
ORTEP drawings of 12h and 12h′ are shown in Figures 3
and 4. In 12h, all of the carbon atoms in the five-membered
ring exist within the same plane, and have an sp2 configura-
tion, while the carbon atom attached to the phenyl group at
C-5 in 12h′ is outside the plane. Thus, this carbon atom has
an sp3 configuration. The C–C bond length between the car-
bon at the 3-position of cyclopentadienone and the methyl
carbon in 12h was 1.489 Å, while the equivalent bond in
12h′ was 1.336 Å.
Ph
Ph
Ph
Ph
[Rh]
Ph
Ph
Ph
CH2
Ph
Ph
H
[Rh]
O
[Rh]
H
12h
– [Rh]
Ph
Ph
Ph
12h'
Scheme 8 A possible mechanism
Since rhodacyclobutenone is more stable than ruth-
enacyclobutenone, the subsequent insertion of alkenes or
alkynes proceeded smoothly, and reductive elimination
would give cyclopentenones or cyclopentadienones in high
yields, respectively, without decarbonylation, even under
an argon atmosphere.
In conclusion, we have succeeded in developing the first
Ru3(CO)12-catalyzed divergent ring-opening coupling reac-
tions of a cyclopropenone with an electron-deficient alkene
to give the linear codimer, a dienoic ester (under an argon
atmosphere) and the cocyclized cyclopentenone (under 20
atm of carbon monoxide), depending on the reaction condi-
tions. On the other hand, [RhCl(η4-1,5-cod)]2 effectively cat-
alyzed the ring-opening cocyclization of a cyclopropenone
with alkenes or alkynes to give the corresponding cyclo-
pentenones or cyclopentadienones in high yields and with
high selectivities.18
Figure 3 X-ray crystal structure of compound 12h (CCDC 1826245)
Figure 4 X-ray crystal structure of compound 12h′ (CCDC 1826246)
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

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Supporting Information
Uemura, S. J. Am. Chem. Soc. 2003, 125, 8862. (f) Nishimura, T.;
Matsumura, S.; Maeda, Y.; Uemura, S. Chem. Commun. 2002, 50.
(g) Nishimura, T.; Matsumura, S.; Maeda, Y.; Uemura, S. Tetrahe-
dron Lett. 2002, 43, 3037.
Supporting information for this article is available online at
https://doi.org/10.1055/s-0037-1609339.
S
u
p
p
ortioInfgrmoaitn
S
u
p
p
ortiInfogrmoaitn
(10) A series of Rh(I)-catalyzed enantioselective cleavage reactions
of a C–C bond in cyclobutanols has been developed inde-
pendently by Cramer and co-workers, see: (a) Seiser, T.; Cramer,
N. Org. Biomol. Chem. 2009, 7, 2835. (b) Seiser, T.; Cramer, N.
Angew. Chem. Int. Ed. 2008, 47, 9294. (c) Seiser, T.; Cramer, N. J.
Am. Chem. Soc. 2010, 132, 5340. (d) Seiser, T.; Cramer, N. Chem.
Eur. J. 2010, 16, 3383. (e) Seiser, T.; Roth, O. A.; Cramer, N.
Angew. Chem. Int. Ed. 2009, 48, 6320. (f) Seiser, T.; Cathomen, G.;
Cramer, N. Synlett 2010, 1699. (g) Seiser, T.; Cramer, N. Angew.
Chem. Int. Ed. 2010, 49, 10163. (h) Souillart, L.; Cramer, N. Chem.
Sci. 2014, 5, 837.
(11) (a) Kondo, T.; Kaneko, Y.; Taguchi, Y.; Nakamura, A.; Okada, T.;
Shiotsuki, M.; Ura, Y.; Wada, K.; Mitsudo, T. J. Am. Chem. Soc.
2002, 124, 6824. (b) Kondo, T.; Niimi, M.; Nomura, M.; Wada, K.;
Mitsudo, T. Tetrahedron Lett. 2007, 48, 2837. (c) Kondo, T.;
Taguchi, Y.; Kaneko, Y.; Niimi, M.; Mitsudo, T. Angew. Chem. Int.
Ed. 2004, 43, 5369. (d) Kondo, T.; Nakamura, A.; Okada, T.;
Suzuki, N.; Wada, K.; Mitsudo, T. J. Am. Chem. Soc. 2000, 122,
6319. (e) Mitsudo, T.; Suzuki, T.; Zhang, S.-W.; Imai, D.; Fujita,
K.; Manabe, T.; Shiotsuki, M.; Watanabe, Y.; Wada, K.; Kondo, T.
J. Am. Chem. Soc. 1999, 121, 1839.
(12) Although the Ni(0)-catalyzed ring-opening dimerization of
cyclopropenones to give 1,4-benzoquinones has been devel-
oped, no catalytic ring-opening coupling reactions of cyclopro-
penones with alkenes have been reported so far. See: Noyori, R.;
Umeda, I.; Takaya, H. Chem. Lett. 1972, 1189. As for Rh(I) cata-
lyzed ring-opening coupling reaction of cyclopropenones with
alkynes, see Ref. 16.
(13) The reactions using other cyclopropenones such as 2,3-dipro-
pylcycloprop-2-en-1-one and bicyclo[6.1.0]non-1(8)-en-9-one
competed with decarbonylation of cyclopropenones, and the
corresponding alkynes were formed as the main products.
Accordingly, a careful tuning of the reaction conditions for each
cyclopropenone is apparently required. As shown in Scheme 1,
compounds 3 and 4 were obtained in moderate yields due to the
decarbonylation of 1 to give 1,2-diphenylethyne. However, no
other by-products which disturb analysis and isolation of the
desired compounds 3 and 4 were obtained at all.
(14) (a) Wong, W.; Singer, S. J.; Pitts, W. D.; Watkins, S. F.; Baddley,
W. H. J. Chem. Soc., Chem. Commun. 1972, 672. (b) Foerstner, J.;
Kakoschke, A.; Wartchow, R.; Butenschön, H. Oragnometallics
2000, 19, 2108.
(15) The free energy profiles of ruthenacycles such as ruthenacy-
clobutenone, ruthenacyclopentene, and (maleoyl)ruthenium
complexes as well as the orbital interactions in the insertion of
ethylene or bicyclo[2.2.1]hept-2-ene were calculated by the
BP86 density functional theory (DFT) method, see Ref. 19. The
6-31G* basis set was used for C, H, and O atoms, and Stutt-
gart/Dresden’s pseudopotential SDD basis set (see Ref. 20) was
used for the Ru atom. See: Wang C., Wu Y.-D. Organometallics.
2008, 27, 6152.
(16) Wender and co-workers also reported a similar [RhCl(CO)]2-cat-
alyzed ring-opening cocyclization of cyclopropenones with
alkynes to give cyclopentadienones; however, the reaction of 1
with 11h gave 12h selectively without 12h′, see: Wender, P. A.;
Paxton, T. J.; Williams, T. J. J. Am. Chem. Soc. 2006, 128, 14814.
(17) Nishinaga, A.; Nakamura, K.; Matsuura, T. J. Org. Chem. 1982, 47,
1431.
References and Notes
(1) (a) C-C Bond Activation; Dong, G., Ed.; Springer-Verlag: Berlin,
2014. (b) Cleavage of Carbon-Carbon Single Bonds by Transition
Metals; Murakami, M.; Chatani, N., Eds.; Wiley-VCH: Weinheim,
2016.
(2) For reviews, see: (a) Kondo, T.; Mitsudo, T. Synlett 2001, 309.
(b) Kondo, T.; Mitsudo, T. Chem. Lett. 2005, 34, 1462. (c) Kondo,
T. Bull. Chem. Soc. Jpn. 2011, 84, 441. (d) Kondo, T. Eur. J. Org.
Chem. 2016, 1232.
(3) (a) Bishop, K. C. III Chem. Rev. 1976, 76, 461. (b) Jun, C.-H. Chem.
Soc. Rev. 2004, 33, 610; and references cited therein.
(4) (a) Murakami, M.; Amii, H.; Ito, Y. Nature 1994, 370, 540.
Further results have been presented elsewhere, see:
(b) Murakami, M.; Itahashi, T.; Amii, H.; Takahashi, K.; Ito, Y. J.
Am. Chem. Soc. 1998, 120, 9949. (c) Murakami, M.; Amii, H.;
Shigeto, K.; Ito, Y. J. Am. Chem. Soc. 1996, 118, 8285. (d) Matsuda,
T.; Shigeno, M.; Murakami, M. Chem. Lett. 2006, 35, 288.
(5) (a) Murakami, M.; Takahashi, K.; Amii, H.; Ito, Y. J. Am. Chem.
Soc. 1997, 119, 9307. (b) Murakami, M.; Itahashi, T.; Ito, Y. J. Am.
Chem. Soc. 2002, 124, 13976. (c) Matsuda, T.; Makino, M.;
Murakami, M. Angew. Chem. Int. Ed. 2005, 44, 4608.
(d) Murakami, M.; Tsuruta, T.; Ito, Y. Angew. Chem. Int. Ed. 2000,
39, 2484. An enantioselective version of the reaction has been
reported, see: (e) Matsuda, T.; Shigeno, M.; Murakami, M. J. Am.
Chem. Soc. 2007, 129, 12086. (f) Matsuda, T.; Shigeno, M.;
Maruyama, Y.; Murakami, M. Chem. Lett. 2007, 36, 744.
(g) Matsuda, T.; Shigeno, M.; Murakami, M. Org. Lett. 2008, 10,
5219. (h) Matsuda, T.; Makino, M.; Murakami, M. Org. Lett.
2004, 6, 1257. (i) Matsuda, T.; Makino, M.; Murakami, M. Bull.
Chem. Soc. Jpn. 2005, 78, 1528. (j) Matsuda, T.; Shigeno, M.;
Makino, M.; Murakami, M. Org. Lett. 2006, 8, 3379. (k) Ishida,
N.; Ikemoto, W.; Murakami, M. Org. Lett. 2012, 14, 3230.
(l) Ishida, N.; Ikemoto, W.; Murakami, M. J. Am. Chem. Soc. 2014,
136, 5912. (m) Murakami, M.; Ashida, S.; Matsuda, T. J. Am.
Chem. Soc. 2005, 127, 6932. (n) Murakami, M.; Ashida, S.;
Matsuda, T. Tetrahedron 2006, 62, 7540. (o) Murakami, M.;
Ashida, S.; Matsuda, T. J. Am. Chem. Soc. 2006, 128, 2166.
(p) Ashida, S.; Murakami, M. Bull. Chem. Soc. Jpn. 2008, 81, 885.
(6) Ko, H. M.; Dong, G. Nat. Chem. 2014, 739.
(7) (a) Parker, E.; Cramer, N. Organometallics 2014, 33, 780.
(b) Souillart, L.; Parker, E.; Cramer, N. Angew. Chem. Int. Ed.
2014, 53, 3001. (c) Souillart, L.; Cramer, N. Angew. Chem. Int. Ed.
2014, 53, 9640. (d) Souillart, L.; Cramer, N. Chem. Eur. J. 2015,
21, 1863For reviews, see:. (e) Seiser, T.; Saget, T.; Tran, D. N.;
Cramer, N. Angew. Chem. Int. Ed. 2011, 50, 7740. (f) Souillart, L.;
Cramer, N. Chem. Rev. 2015, 115, 9410.
(8) For the first catalytic cleavage of a C–C bond in unstrained tert-
homoallylic alcohols through β-carbon elimination, see: Kondo,
T.; Kodoi, K.; Nishinaga, E.; Okada, T.; Morisaki, Y.; Watanabe,
Y.; Mitsudo, T. J. Am. Chem. Soc. 1998, 120, 5587.
(9) (a) Nishimura, T.; Ohe, K.; Uemura, S. J. Am. Chem. Soc. 1999,
121, 2645. (b) Nishimura, T.; Ohe, K.; Uemura, S. J. Org. Chem.
2001, 66, 1455. (c) Nishimura, T.; Uemura, S. J. Am. Chem. Soc.
1999, 121, 11010. (d) Nishimura, T.; Uemura, S. Synlett 2004,
201, 201. Enantioselective version of these reactions have also
been reported, see: (e) Nishimura, T.; Matsumura, S.; Maeda, Y.;
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

F
T. Kondo et al.
Cluster
Synlett
(18) Ruthenium-Catalyzed Divergent Ring-Opening Coupling
Reactions of 2,3-Diphenylcycloprop-2-en-1-one (1) with
Methyl Acrylate (2); General Procedure
Yield: 137.2 mg (47%); pale yellow solid; 1H NMR (300 MHz,
CDCl3): δ = 2.75–2.93 (dd, J = 16.0, 18.5 Hz 1 H), 2.76–2.95 (dd,
J = 20.0, 18.5 Hz, 1 H), 3.50 (s, 3 H), 4.25–4.28 (dd, J = 4.2, 3.0 Hz,
1 H), 7.11–7.25 (m, 10 H); 13C NMR (75 MHz, CDCl3): δ = 39.26,
46.76, 52.42, 128.18, 128.23, 128.35, 128.45, 129.45, 129.87,
131.13, 133.99, 141.07, 164.94, 172.62, 204.60; MS (EI): m/z =
292 (M+).
A mixture of 2,3-diphenylcycloprop-2-en-1-one (1) (1.0 mmol),
methyl acrylate (2) (3.0 mL), and Ru3(CO)12 (0.066 mmol) was
placed in a two-necked 20-mL Pyrex flask equipped with a
magnetic stir bar and a reflux condenser under a flow of argon.
The reactor was connected to a balloon (1 L) and the reaction
was carried out at 100 °C for 20 hours with stirring. After the
reaction mixture had been cooled, the products were analyzed
by GC and GC/MS, and isolated by medium-pressure column
chromatography (SiO2 60 μm, eluent: EtOAc/hexane). The reac-
tions under carbon monoxide pressure were carried out in a 50-
mL stainless steel autoclave at 160 °C for 20 hours.
exo-2,3-Diphenyl-3a,4,5,6,7,7a-hexahydro-1H-4,7-metha-
noinden-1-one (8)
Yield: 183.0 mg (61%); orange solid; 1H NMR (300 MHz, CDCl3):
δ = 0.98–1.04 (m, 1 H), 1.21–1.27 (m, 1 H), 1.38–1.44 (m, 2 H),
1.62–1.68 (m, 2 H), 2.10–2.36 (m, 1 H), 2.50 (d, J = 5.4 Hz, 1 H),
2.59–2.62 (m, 1 H), 3.20 (d, J = 5.4 Hz, 1 H), 7.17–7.33 (m, 10 H);
13C NMR (75 MHz, CDCl3): δ = 28.77, 28.91, 31.52, 38.23, 39.43,
50.65, 53.99, 127.66, 128.25, 128.31, 128.47, 129.24, 129.39,
132.11, 135.03, 142.54, 169.85, 208.50; MS (EI): m/z = 300 (M+).
3-Methyl-2,4,5-triphenylcyclopenta-2,4-dien-1-one (12h)
Yield: 74.1 mg (23%); dark purple solid; 1H NMR (300 MHz,
CDCl3): δ = 2.07 (s, 3 H), 7.11–7.45 (m, 15 H); 13C NMR (75 MHz,
CDCl3): δ = 14.52, 124.61, 125.64, 127.27, 127.30, 127.93,
128.21, 128.49, 128.59, 128.62, 129.54, 129.82, 130.68, 131.34,
133.73, 154.12, 154.46, 200.42; MS (EI): m/z = 322 (M+).
4-Methylene-2,3,5-triphenylcyclopent-2-en-1-one (12h′)
Yield: 64.4 mg (20%); light purple solid; 1H NMR (300 MHz,
CDCl3): δ = 4.34 (s, 1 H), 5.30 (s, 1 H), 5.44 (s, 1 H), 7.20–7.41 (m,
15 H); 13C NMR (75 MHz, CDCl3): δ = 56.05, 114.81, 127.20,
127.92, 128.09, 128.50, 128.58, 128.77, 128.94, 129.77, 130.66,
133.16, 137.69, 139.68, 148.91, 164.47, 202.67; MS (EI): m/z =
322 (M+).
Rhodium-Catalyzed Ring-Opening Cocyclization of 2,3-
Diphenylcycloprop-2-en-1-one (1) with Alkenes/Alkynes;
General Procedure
A mixture of 2,3-diphenylcycloprop-2-en-1-one (1) (1.0–1.5
mmol), [RhCl(η4-1,5-cod)]2 (0.10 mmol), solvent (3.0 mL), and
an alkene (3.0 mmol) or an alkyne (1.0 mmol) was placed in a
two-necked 20-mL Pyrex flask equipped with a magnetic stir
bar and a reflux condenser under a flow of argon. The reactor
was connected to a balloon (1 L) and the reaction was carried
out at 100 °C for 20 hours with stirring. After the reaction
mixture had been cooled, the products were analyzed by GC
and GC/MS, and isolated by medium-pressure column chroma-
tography (SiO2 60 μm, eluent: EtOAc/hexane). The reactions
under ethylene were carried out in a 50-mL stainless steel auto-
clave.
The MS and NMR data of the representative new compounds, 4,
8, 12h, and 12h′ are reported below. See also the Supporting
Information.
(19) (a) Becke, A. D. Phys. Rev. A 1988, 38, 3098. (b) Perdew, J. P. Phys.
Rev. B 1986, 33, 8822.
(20) (a) Andrae, D.; Häußermann, U.; Dolg, M.; Stoll, H.; Preuß, H.
Theor. Chim. Acta 1990, 77, 123. (b) Dolg, M.; Wedig, U.; Stoll, H.;
Preuss, H. J. Chem. Phys. 1987, 86, 866.
Methyl
(4)
4-Oxo-2,3-diphenylcyclopent-2-ene-1-carboxylate
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F