Asymmetric cross-dimerization between methyl methacrylate and substituted alkene by Ru(0)-bicyclononadiene complex

Article abstract of DOI:10.1021/ol400963d

New Ru(0)-naphthalene complexes containing a bicyclononadiene ligand catalyze the linear cross-dimerization between methyl methacrylate and substituted alkenes by an oxidative coupling mechanism. The chiral (S,S)-2-methylbicyclo[3.3.1]nona-2,6-diene complex (S,S)-1b catalyzes asymmetric linear cross-dimerization between methyl methacrylate and 2,5-dihydrofuran to give the cross-dimer in 74% yield in 80% ee.

Full text of DOI:10.1021/ol400963d

ORGANIC
LETTERS
2013
Vol. 15, No. 10
2486–2489
Asymmetric Cross-Dimerization between
Methyl Methacrylate and Substituted Alkene
by Ru(0)ꢀBicyclononadiene Complex†
Yuki Hiroi,‡ Nobuyuki Komine,‡,§ Sanshiro Komiya,‡,§ and Masafumi Hirano*,‡,§
Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of
Agriculture and Technology, 2-24-26 Nakacho, Koganei, Tokyo 184-8588, Japan, and
Japan Science and Technology Agency (JST), ACT-C, 4-1-8 Honcho, Kawaguchi,
Saitama 332-0012, Japan
hrc@cc.tuat.ac.jp
Received April 8, 2013
ABSTRACT
New Ru(0)ꢀnaphthalene complexes containing a bicyclononadiene ligand catalyze the linear cross-dimerization between methyl methacrylate
and substituted alkenes by an oxidative coupling mechanism. The chiral (S,S)-2-methylbicyclo[3.3.1]nona-2,6-diene complex (S,S)-1b catalyzes
asymmetric linear cross-dimerization between methyl methacrylate and 2,5-dihydrofuran to give the cross-dimer in 74% yield in 80% ee.
Catalytic dimerization of substituted alkenes is one of
the most powerful and environmentally benign processes
for the formation of CꢀC bonds, and it proceeds with
complete atom efficiency.1 However, cross-dimerization be-
tween substituted alkenes remains difficult, and the coupling
partners are limited to norbornene/norbornadiene2 and vinyl
compounds.3 One of the ultimate goals for this process is the
asymmetric linear cross-dimerization of alkenes. However, few
such reactions are known, although asymmetric [2 þ 2 þ 2]
cyclotrimerization of alkynes is of topical interest.4 The
pioneering examples involve the cross-dimerizations between
ethylene and styrenes5 or between alkenes and alkynes.6
However, the asymmetric linear cross-dimerization between
substituted alkenes is unprecedented to the best of our
knowledge.
† This paper is dedicated to Prof. Irina Petrovna Beletskaya at Moscow
State University for her contribution to metal-catalyzed reactions.
‡ Tokyo University of Agriculture and Technology.
We have studied stoichiometric and catalytic homo- and
cross-dimerization by Ru(η6-naphthalene)(η4-1,5-COD)
(2; COD = cyclooctadiene) and related compounds.7
For example, the complex (η4-1,5-COD)[trans-2,5-bis-
(methoxycarbonyl)ruthenacyclopentane] was isolated by
the stoichiometric reaction of 2 with methyl acrylate,
presumably formed by a prostereogenic face-selective
§ Japan Science and Technology Agency (JST).
(1) Trost, B. M.; Toste, F. D.; Pinkerton, A. B. Chem. Rev. 2001, 101,
2067 and references cited therein.
€
(2) (a) Hilt, G.; du Mesnil, F.; Luers, S. Angew. Chem., Int. Ed. 2001,
40, 387. (b) Ura, Y.; Tsujita, H.; Wada, K.; Kondo, T.; Mitsudo, T.
J. Org. Chem. 2005, 70, 6623.
(3) (a)Kwon, K. H.;Lee, D. W.;Yi, C. S. Organometallics 2012, 31, 495.
(b) Kwon, K. H.; Lee, D. W.; Yi, C. S. Angew. Chem., Int. Ed. 2011, 50,
1692. (c) Ogoshi, S.; Haba, T.; Ohashi, M. J. Am. Chem. Soc. 2009, 131,
10350. (d) Grutters, M. M. P.; van der Vlugt, J. I.; Pei, Y.; Mills, A. M.;
(4) Recent review: Shibata, Y.; Tanaka, K. Synthesis 2012, 44, 323
and references cited therein.
(5) (a) Jiang, G.; List, B. Chem. Commun. 2011,47, 10022. (b) RajanBabu,
T. V. Synlett 2009, 6, 853. (c) Lassauque, N.; Francio, G.; Leitner, W. Adv.
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Muller, G.; Ordinas, J. I.; Mezzetti, A.; Maestro, M. A.; Font-Bardia, M.;
Solans, X. Organometallics 2005, 24, 4961. (g) Marciniec, B.; Kownacki, I.;
Kubicki, M. Organometallics 2002, 21, 3263. (h) Kretschmer, W. P.;
Troyanov, S. I.; Meetsma, A.; Hessen, B.; Teuben, J. H. Organometallics
1998, 17, 284. (i) Kawamoto, K.; Tatani, A.; Imanaka, T.; Teranishi, S. Bull.
Chem. Soc. Jpn. 1971, 44, 1239. (j) Barlow, M. G.; Bryant, M. J.; Haszeldine,
R. N.; Mackie, A. G. J. Organomet. Chem. 1970, 21, 215. (k) Wang, Q.-S.;
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r
10.1021/ol400963d
Published on Web 05/09/2013
2013 American Chemical Society

oxidative coupling reaction,8 and this ruthenacyclopen-
tane acts as an active catalyst for the tail-to-tail dimeriza-
tion of methyl acrylate.9 In these reactions, the 1,5-COD
ligand remains attached on Ru throughout the reaction.
Since these reactions are significantly suppressed by the
addition of tertiary phosphine,7e employment of a cyclic
diene ligand isthe key tothese catalyses. Thus, the presence
of a chiral cyclic diene ligand in the Ru(0)ꢀnaphthalene
complex could potentially provide an efficient catalyst
for asymmetric linear cross-dimerization of substituted
alkenes.
(Me-bnd) (3b),16 2,6-dimethylbicyclo[3.3.1]nona-2,6-diene
(Me2-bnd) (3c), and 9-oxabicyclo[3.3.1]nona-2,6-diene
(oxa-bnd) (3d)] by a modification of the literature method.
Ru(η6-naphthalene)(cyclic diene)s (1aꢀd) were prepared
from 3aꢀd similarly to 2 in moderate yields (Scheme 1).17
Scheme 1. Synthesis of Ru(0)ꢀBicyclononadiene Complexes
Just a decade ago, Hayashi et al. introduced a chiral
cyclic diene ligand into transition-metal-mediated asym-
metric catalysis.10 Later, Carreira et al. developed very
efficient synthetic method of a chiral diene from commer-
cially available natural product.11 All these systems cur-
rently constitute a powerful asymmetric induction method
by the CꢀC bond forming reaction.12 However, chiral
cyclic dienes are dominantly employed for group 9 com-
plexes, and have never been appliedto Ru complexes. They
also have never used as an ancillary ligand for the catalysts
in the cross-dimerization of alkenes. Herein we report the
synthesis of a series of Ru(0) complexes bearing a bicyclo-
nonadiene ligand,13,14 their application to the linear cross-
dimerization between substituted alkenes and their suc-
cessful use for the first asymmetric reaction.
Compounds 1aꢀd were characterized by 1H NMR,
1
1
1Hꢀ H COSY, 13C NMR, and 13Cꢀ H HETCOR spec-
tra, IR spectra, and elemental, analysis and 1aꢀc were also
characterized by the X-ray analysis.
The catalytic cross-dimerizations between MMA and
substituted alkenes are listed in Table 1. Complex 1a
(1 mol %) showed quite high catalytic activity toward
the cross-dimerization betweenMMA and 2,5-dihydrofur-
an, the product being formed in 85% yield (4a/4b/4c =
17/76/7) at 0 °C for 4 h under solvent-free conditions. In
contrast, complex 2 gives almost exclusively compound 4c
(Table 1, entries 2 and 1).7e The Meꢀbnd complex 1b was
also displayed high product selectivity, although the cata-
lytic activity is slightly lower (entry 3). The catalytic
activity is further diminished for the Me2ꢀbnd complex
1c (entry 4). In contrast to 1aꢀc, the oxaꢀbnd analogue 1d
produced mainly 4c (entry 5). We also found norbornene
and trimethoxyvinylsilane to be good coupling partners
with MMA. The cross-dimerization between MMA and
norbornene catalyzed by 1a or 1d produced 5b in high
yield with E and exclusive exo selectivities (entries 7, 10).
These cross-dimerizations using MMA are unprecedented,
although there are a few reports of cross-dimerization
between acrylates and substituted alkenes.18 The cross-
dimerization between MMA and trimethoxyvinylsilane
dominantly produced the tail-to-tail cross-dimer 6a by 1a
with high regio- and E-selectivities (entry 12). These results
In order to study the catalytic activity of the bicyclono-
nadiene complex, we have prepared racemic Ru(acac)2-
(cyclic diene) (3)15 [cyclic diene = bicyclo[3.3.1]nona-2,6-
diene (bnd) (3a), 2-methylbicyclo[3.3.1]nona-2,6-diene
(7) (a) Hirano, M.; Okamoto, T.; Komine, N.; Komiya, S. Organo-
metallics 2012, 31, 4639. (b) Hirano, M.; Arai, Y.; Hamamura, Y.;
Komine, N.; Komiya, S. Organometallics 2012, 31, 4006. (c) Hirano, M.;
Sakate, Y.; Inoue, H.; Arai, Y.; Komine, N.; Komiya, S.; Wang, X.-Q.;
Bennett, M. A. J. Organomet. Chem. 2012, 708ꢀ709, 46. (d) Hirano, M.;
Arai, Y.; Komine, N.; Komiya, S. Organometallics 2010, 29, 5741. (e)
Hiroi, Y.; Komine, N.; Hirano, M.; Komiya, S. Organometallics 2011,
30, 1307. (f) Hirano, M.; Hiroi, Y.; Komine, N.; Komiya, S. Organo-
metallics 2010, 29, 3690.
(8) The word “oxidative coupling” is also used for the coupling of two
molecular entitities through an oxidative process with an oxidant like a
dehydrogenative coupling. However, in this paper, the oxidative cou-
pling reaction is defined as the metal induced coupling reactions between
two unsaturated coupounds to give a metallacycle: Crabtree, R. H. The
Organometallic Chemistry of the Transition Metals, 3rd ed.; Wiley:
New York, 2001; pp 168.
(9) Hirano, M.; Sakate, Y.; Komine, N.; Komiya, S.; Bennett, M. A.
Organometallics 2009, 28, 4902.
(10) Hayashi, T.; Ueyama, K.; Tokunaga, N.; Yoshida, K. J. Am.
Chem. Soc. 2003, 125, 11508.
(11) Fischer, C.; Defieber, C.; Suzuki, T.; Carreira, E. M. J. Am.
(16) 2-Methylbicyclo[3.3.1]nona-2,6-diene was newly synthesized
(see the Supporting Information).
Chem. Soc. 2004, 126, 1628.
(12) Recent review on chiral diene ligands: Defieber, C.; Grutzmacher,
H.; Carreira, E. M. Angew. Chem., Int. Ed. 2008, 47, 4482.
(13) Synthesis of bicyclononadiene ligands: (a) Henkel, J. G.; Faith,
W. C.; Hane, J. T. J. Org. Chem. 1981, 46, 3483. (b) Graetz, B.;
Rychnovsky, S.; Leu, W.-H.; Farmer, P.; Lin, R. Tetrahedron: Asym-
(17) This synthetic route is a modification of the literature methods:
(a) Bennett, M. A.; Byrnes, M. J.; Willis, A. C. Organometallics 2003, 22,
1018. (b) Bennett, M. A.; Neumann, H.; Thomas, M.; Wang, X.-Q.
Organometallics 1991, 10, 3237.
(18) Linear cross-dimerizations between enone and vinylsilane: (a)
^
€
metry 2005, 16, 3584. (c) Hegemann, K.; Frohlich, R.; Haufe, G. Eur. J.
Simon, M.-O.; Martinez, R.; Genet, J.-P.; Darsesa, S. Adv. Synth. Catal.
Org. Chem. 2004, 10, 2181.
2009, 351, 153. (b) Sato, T.; Kakiuchi, F.; Chatani, N.; Murai, S. Chem.
Lett. 1998, 893. (c) Trost, B. M.; Imi, K.; Davies, I. W. J. Am. Chem. Soc.
1995, 117, 5371. (d) Kakiuchi, F.; Tanaka, Y.; Sato, T.; Chatani, N.;
Murai, S. Chem. Lett. 1995, 679. Linear cross-dimerizations of sub-
stituted olefins: (e) Tsujita, H.; Ura, Y.; Matsuki, S.; Wada, K.; Kondo,
T.; Mitsudo, T. Angew. Chem., Int. Ed. 2007, 46, 5160. (f) Tsujita, H.;
Ura, Y.; Wada, K.; Kondo, T.; Mitsudo, T. Chem. Commun. 2005, 5100.
(g) Nikishim, G. I.; Klimova, T. E.; Ignatenko, A. V.; Kovalev, I. P.
TetrahedronLett. 1991, 32, 1077. (h) Oehme, G.; Grassert, I.; Mennenga,
H.; Baudisch, H. J. Mol. Catal. 1986, 37, 53. (I) Saegusa, T.; Ito, Y.;
Tomita, S.; Kinoshita, H. J. Org. Chem. 1970, 35, 670.
(14) Pioneering chiral bicyclononadine complexes of Rh: (a) Otomaru,
Y.; Tokunaga, N.; Shintani, R.; Hayashi, T. Org. Lett. 2005, 7, 307. (b)
Otomaru, Y.; Kina, A.; Shintani, R.; Hayashi, T. Tetrahedon: Asymmetry
2005, 16, 1673. (c) Mayr, M.; Bataille, C. J. R.; Gosiewska, S.; Raskatov,
J. A.; Brown, J. M. Tetrahedron: Asymmetry 2008, 19, 1328. (d) Gosiewska,
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(15) Compounds 3a, 3b, and 3d were observed as a mixture of
diastereomers. Compound 3c was observed as a single diastereomer
rac-Δ-Ru(acac)2((S,S)-Me2-bnd).
Org. Lett., Vol. 15, No. 10, 2013
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Table 1. Catalytic Cross-Dimerization of MMA with Substituted Alkenesa,b,e
a Typical conditions: MMA (2.54 mmol), 2,5-dihydrofuran (2ꢀ5 equiv vs MMA), cat. (1 or 5 mol % vs MMA), neat. (entries 1ꢀ5); MMA
(1.04 mmol), alkene (1.2ꢀ5 equiv vs. MMA), cat. (2 or 5 mol %), THF, 2 mL (entries 6ꢀ10); MMA (0.52 mmol), alkene (2 equiv vs MMA), cat. (5 mol %),
THF, 1 mL (entries 11ꢀ15). b Yields are estimated on the basis of MMA. c Determined by GLC. d A negligible amount of E-6b was observed. e In these
reactions, small amounts of trimers (cross dimers between 4a or 5a and alkene) were observed.
point to the possibility of chiral induction if chiral bicy-
clononadienes are introduced into the catalyst. The ligands
(S,S)-bnd and (S,S)-Meꢀbnd were obtained by the kinetic
resolution of bicyclo[3.3.1]nonane-2,6-dione13 and the
corresponding chiral naphthalene complexes (S,S)-1a
and (S,S)-1b were successfully prepared in 59% and 43%
yields, respectively. The chiral catalyst (S,S)-1b (10 mol %)
in the cross-dimerization between MMA and 2,5-dihydro-
furan at 20 °C for 7 days under solvent-free conditions
provided colorless oil consisting of cross-dimers in 83%
total yield (eq 1).19 Compound 4b was dominantly ob-
tained in 74% yield (E/Z = 93/7) and 80% ee for (E)-4b,
which was determined by chiral HPLC.20 This is the first
asymmetric cross-dimerization between substituted al-
kenes. Note that 4b was formed always as dominant
product, suggesting direct formation of 4b by the coupling
reaction. In contrast, there was no asymmetric induction in
the presence of (S,S)-1a. (E)-4b was isolated by silica gel
column chromatography (hexane/ethyl acetate = 5/1 (v/v))
and its optical rotation was determined to be [R]20
=
D
ꢀ13.7 (c = 0.59, 80% ee, CHCl3); the absolute configura-
tion can be determined to be (R).21 The present results are
consistent with the catalytic cycle shown in Scheme 2. After
displacement of the 6e naphthalene ligand, MMA and 2,5-
dihydrofuran coordinate as 4e and 2e donors, respectively.
This is the origin of the chemoselectivity for this cross-
dimerization. Then an oxidative coupling reaction fol-
lowed by the β-hydride elimination and reductive elimina-
tion release the final coupling product. Note that a
ruthenacyclopentane was isolated in the related example,
suggesting an oxidative coupling mechanism for the pres-
ent system.9,22
(19) The formation mechanism for 4d is not clear to date. One of the
possible pathways is prior isomerization of 2,5-dihydrofuran to 2,3-
dihydrofuran followed by the coupling with MMA.
(20) The yield decreased to 48% ((S,S)-1b: 5 mol%, 4a/E-4b/
Z-4b/4c = 2/90/6/2) by the reaction at 50 °C: (E)-4b = 73% ee. No
asymmetric induction was observed when norbornene was used as a
coupling partner.
(21) (ꢀ)-(E)-4b was derivatized to the corresponding 2-naphthyl ester
as a pure crystalline (E)-form, which was converted into the known
optically active methyl tetrahydro-3-furanoate (7) ([R]18D = ꢀ20.3, c =
0.12, 84% ee, MeOH) by ozonolysis. By comparison of this data to the
literature, we can determined the absolute configuration of (ꢀ)-(E)-4b to
be (R): Horiuchi, T.; Ohta, T.; Shirakawa, E.; Nozaki, K.; Takaya, H.
J. Org. Chem. 1997, 62, 4285.
Since no asymmetric induction took place at all when
(S,S)-1a was employed in this reaction, the Me group in
(22) We believe alternative Alderꢀene-type reaction starting from
insertion of an alkene into a hydrido complex is ruled out because such a
process gives a different product for the related reaction of ethyl acrylate
with 2,5-dihydrofuran; see ref 7e.
2488
Org. Lett., Vol. 15, No. 10, 2013

Scheme 2. Possible Catalytic Cycle
Scheme 3. Relative Stability for the Coordinated MMA at Ru(0)
by DFT Calculations and the Rotamers of 2,5-Dihydrofuran
In summary, we have reported a series of new Ru(η6-
naphthalene)(η4-bicyclononadiene) complexes and used
them to catalyze the linear cross-dimerization of substi-
tuted alkenes. Unsaturated compounds containing an
asymmetric center are readily accessible from simple sub-
stituted alkenes through an efficient asymmetric oxidative
coupling.
Meꢀbnd must play a key role in controlling the stereo-
chemistry. The consistent mechanism for the asymmetric
induction can be explained as follows. The DFT calcula-
tions show that a MMA molecule preferentially coordi-
nates by the si face at the Ru(0) center to avoid repulsion
between the methylene group in MMA and the Me group
in Meꢀbnd ligand (Scheme 3, F1, L = MeCN). If 2,5-
dihydrofuran coordinates to the Ru(0) as L in F1, the
enantioselectivity is determined by the conformation of the
coordinating 2,5-dihydrofuran.
Because there are no appropriate terms for such rota-
mers, we have tentatively defined the two rotamers of 2,5-
dihydrofuran, whose CdC bond is assumed to be coplanar
with that of MMA as anti and eclipsed F1 with respect to
the Meꢀbnd ligand. The anti rotamer, anti F1 is 7.8 kJ
molꢀ1 more stable than the eclipsed one according to DFT
calculations. An oxidative coupling reaction takes place
from antiF1togivea ruthenacyclopentaneG followedbya
sequence of axial β-hydride elimination from the methy-
lene group in G and subsequent by reductive elimination,
thus giving (R)-(E)-4b directly (Scheme 3).
Acknowledgment. We are grateful to Prof. M. A. Bennett
(ANU) for helpful discussions. We also thank Ms. S. Kiyota
(TUAT) for elemental analysis and Prof. T. Takeda
(TUAT) for ozonolysis of 4b. We thank Daicel Co. for
supporting the chiral HPLC measurements. We thank JST
ACT-C and MEXT for financial support.
Supporting Information Available. Text, tables, and
figures giving full experimental details involving the
characterizations of 1aꢀd, 3aꢀd, 4b, 5a,b, and 6a,b,
X-ray data for 1aꢀc and 3aꢀd, and DFT calculations.
This material is available free of charge via the Internet at
http://pubs.acs.org.
The authors declare no competing financial interest.
Org. Lett., Vol. 15, No. 10, 2013
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