Ruthenium-triggered ring opening of ethynylcyclopropanes: [3+2] cycloaddition with aldehydes and aldimines involving metal allenylidene intermediates

Article abstract of DOI:10.1002/anie.201207801

It's complex: Ruthenium-catalyzed [3+2] cycloaddition of ethynylcyclopropanes with aldehydes and aldimines has been found to give the corresponding 2-ethynyltetrahydrofurans or -pyrrolidines in high to excellent yields. In both cases, the formation of a ruthenium allenylidene complex as a key reactive intermediate is supported by density functional theory calculations. Cp=η⁵-C₅Me₅. Copyright

Full text of DOI:10.1002/anie.201207801

Angewandte
Chemie
DOI: 10.1002/anie.201207801
Synthetic Methods
Ruthenium-Triggered Ring Opening of Ethynylcyclopropanes:
[3+2] Cycloaddition with Aldehydes and Aldimines Involving Metal
Allenylidene Intermediates**
Yoshihiro Miyake, Satoshi Endo, Taichi Moriyama, Ken Sakata,* and Yoshiaki Nishibayashi*
Transition metal allenylidene complexes have attracted con-
siderable attention as versatile organometallic species for
carbon-rich architecture, material science, and reactive inter-
mediates in various organic transformations.[1–3] Since the first
discovery of metal allenylidene complexes,[4] their structures,
electronic properties, and stoichiometric reactivities have
been studied extensively owing to the discovery of general
method of access to metal allenylidene complexes by simple
activation of propargylic alcohols (Scheme 1a).[5] Although
transformations[8–11] involving ruthenium allenylidene com-
plexes as key and common intermediates together with their
enantioselective versions. Furthermore, other research groups
have also developed a variety of catalytic reactions involving
metal allenylidene complexes as key intermediates.[1,12–15]
However, readily accessible precursors for formation of
allenylidene complexes are limited only to propargylic
alcohols and their derivatives. We have now designed an
ethynylcyclopropane bearing two carboxy groups at the
homopropargylic position as a new accessible precursor for
a metal allenylidene complex. The isomerization of a cyclo-
propyl vinylidene complex can lead to the corresponding
metal allenylidene complex, which is expected to serve as
a 1,3-dipolar synthon at the g and e positions (Scheme 1b). In
fact, we report herein the ruthenium-catalyzed [3+2] cyclo-
addition of ethynylcyclopropanes with aldehydes and aldi-
mines, where ruthenium allenylidene complexes serve as
reactive intermediates. The scope and limitations of the
catalytic [3+2] cycloaddition are described together with the
density functional theory (DFT) calculations on the proposed
reaction pathway, including the generation of ruthenium
allenylidene complexes.
Treatment of 1a with benzaldehyde (2a; 5 equiv) and
BF3·OEt2 (5 equiv) in the presence of 5 mol% of the
methanethiolato-bridged diruthenium complex [{Cp*RuCl-
(m2-SMe)}2][9,16] (3a; Cp* = h5-C5Me5) in ClCH2CH2Cl at
room temperature for 15 hours afforded dimethyl 5-ethynyl-
2-phenyltetrahydrofuran-3,3-dicarboxylate (4a) in 88% yield
(Table 1, entry 1). The reaction of 1a with 3 equivalents of 2a
proceeded smoothly, but a lower yield (67%) of 4a was
observed (Table 1, entry 2). When the amount of BF3·OEt2
was reduced to 3 equivalents relative to 1a, the yield of 4a
decreased slightly (Table 1, entry 3). We confirmed that no
formation of 4a was observed in either the absence of
BF3·OEt2 or 3a, thus indicating that use of both BF3·OEt2 and
3a is necessary for producing 4a. Other diruthenium com-
plexes such as the complex bearing the sterically more
demanding SiPr moiety [{Cp*RuCl(m2-SiPr)}2] (3b) and the
cationic diruthenium complex [Cp*RuCl(m2-SMe)RuCp*-
(OH2)][OTf] (3c; OTf = OSO2CF3) exhibited a lower cata-
lytic activity (Table 1, entries 4 and 5). Noteworthy is that
only diruthenium complexes work as effective catalysts to
promote the cycloaddition reaction. In fact, mononuclear
ruthenium complexes such as [TpRu(PPh3)(CH3CN)2][PF6]
(Tp = tris(1-pyrazolyl)borate), [CpRuCl(PPh3)2] (Cp = h5-
C5H5), and [(h5-C9H7)Ru(dppe)][PF6] (dppe = 1,2-bis(diphe-
nylphosphino)ethane) did not promote this cycloaddition at
all.
Scheme 1. Approach to formation of metal allenylidene complexes.
the involvement of transition metal allenylidene complexes in
catalytic reactions was reported for the first time in 1992,[6]
significant progress has not been made until recently. Since
our finding of the ruthenium-catalyzed propargylic substitu-
tion reactions of propargylic alcohols with nucleophiles,[7] we
have continuously studied a variety of unique catalytic
[*] Dr. Y. Miyake, S. Endo, Dr. T. Moriyama, Prof. Dr. Y. Nishibayashi
Institute of Engineering Innovation, School of Engineering
The University of Tokyo
Yayoi, Bunkyo-ku, Tokyo, 113-8656 (Japan)
E-mail: ynishiba@sogo.t.u-tokyo.ac.jp
Prof. Dr. K. Sakata
Faculty of Pharmaceutical Sciences, Hoshi University
Ebara, Shinagawa-ku, Tokyo 142-8501 (Japan)
E-mail: sakata@hoshi.ac.jp
[**] This work was supported by a Grant-in-Aid for Scientific Research on
Innovative Areas “Advanced Molecular Transformations by Orga-
nocatalyst” from the MEXT (Japan).
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201207801.
Angew. Chem. Int. Ed. 2013, 52, 1 – 6
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

.
Angewandte
Communications
Table 1: Ruthenium-catalyzed [3+2] cycloaddition of dimethyl 2-ethynyl-
cyclopropane-1,1-dicarboxylate (1a) with benzaldehyde (2a).[a]
Table 2: Ruthenium-catalyzed [3+2] cycloaddition of 1 with 2.[a]
Entry
R
Ar
Yield [%][b] (trans/cis)[c]
Entry
Catalyst
2a (equiv)[b]
4a
yield [%][c] (trans/cis)[d]
1
2
3
4
5
6
7
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Et (1b)
Ph (2a)
88 (4a; 2:1)
87 (4b; 2:1)
81 (4c; 2:1)
80 (4d; 2:1)
61 (4e; 1:1)
76 (4 f; 2:1)
75 (4g; 2:1)
56 (4h; 2:1)
40 (4i; 1:1)
72 (4j; 2:1)
74 (4k; 2:1)
70 (4l; 2:1)
72 (4m; 3:2)
4-MeOC6H4 (2b)
4-MeC6H4 (2c)
3-MeC6H4 (2d)
2-MeC6H4 (2e)
4-ClC6H4 (2 f)
4-FC6H4 (2g)
4-NO2C6H4 (2h)
1-naphthyl (2i)
2-naphthyl (2j)
Ph (2a)
1
2
3a
3a
3a
3b
3c
5
3
5
5
5
88 (2:1)
67 (2:1)
74 (2:1)
73 (2:1)
51 (2:1)
3[e]
4
5
[a] All reactions of 1a (0.30 mmol) with 2a and BF3·OEt2 (1.5 mmol)
were carried out in the presence of catalyst (0.015 mmol) in ClCH2CH2Cl
(6 mL) at room temperature for 15 h. [b] Equivalents relative to 1a.
[c] Yield of isolated product. [d] Determined by 1H NMR spectroscopy.
[e] BF3·OEt2 (0.90 mmol; 3 equiv relative to 1a) was used.
8[d]
9[e]
10[f]
11
12
13
Et (1b)
Et (1b)
4-MeOC6H4 (2b)
4-MeC6H4 (2c)
[a] All reactions of 1 (0.30 mmol) with 2 (1.5 mmol) and BF3·OEt2
(1.5 mmol) were carried out in the presence of 3a (0.015 mmol) in
ClCH2CH2Cl (6 mL) at room temperature for 15 h. [b] Yield of isolated
product. [c] Determined by 1H NMR spectroscopy. [d] For 38 h. [e] For
18 h. [f] For 20 h.
Other reactions of 1 with a variety of aldehydes (2) were
investigated by using 3a as the catalyst. Typical results are
shown in Table 2. The introduction of a substituent such as
methoxy, methyl, chloro, or fluoro groups at the para position
of the benzene ring of 2 did not have much of an effect on the
yield of 4 (Table 2, entries 2, 3, 6, and 7). The reaction of 3-
methylbenzaldehyde (2d) and 2-naphthaldehyde (2j) took
place smoothly to give the corresponding products 4d and 4j
in high yields (Table 2, entries 4 and 10), while that of p-
nitrobenzaldehyde (2h) and sterically hindered aldehydes
such as o-tolylcarboaldehyde (2e) and 1-naphthylcarboalde-
hyde (2i) afforded a slightly lower product yield (Table 2,
entries 5, 8, and 9). Unfortunately, no reaction of 1a with
cyclohexanecaboxaldehyde, benzophenone, and acetone oc-
curred at all under the same reaction conditions. When
diethyl 2-ethynylcyclopropane-1,1-dicarboxylate (1b) was
used in place of 1a, the cycloaddition products 4k, 4l, and
4m were obtained in similar yields (Table 2, entries 11–13).
The reaction of dimethyl 2-(2-phenylethynyl)cyclopropane-
1,1-dicarboxylate (1c), bearing an internal alkyne moiety,
with 2a did not give the corresponding cycloaddition product;
1c was recovered in 63% (see Scheme S1a in the Supporting
Information).[18] In addition, no formation of the correspond-
ing product was observed when either 1d or 1e was used in
place of 1a, whereas the reaction of 1 f proceeded under
similar reaction conditions, but only a small amount of the
product was obtained (Scheme S1b-d).[18] These results clearly
indicate that use of 2-ethynylcyclopropane bearing two
carboxy groups is necessary to promote the cycloaddition.
This methodology for the preparation of 4 can be applied
to the formation of ethynylpyrrolidines (6). Typical results are
shown in Table 3. Treatment of 1a with N-benzylidene-4-
methylbenzenesulfonamide (5a; 5 equiv) and Sc(OTf)3
Table 3: Ruthenium-catalyzed [3+2] cycloaddition of 1 with 5.[a]
Entry
R
Ar
Yield [%][b] (trans/cis)[c]
1
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Me (1a)
Et (1b)
Ph (5a)
Ph (5a)
Ph (5a)
Ph (5a)
88 (6a; 1:50)
12[e] (6a; –)
0 (6a)
2[d]
3[f]
4[g]
5[h]
6
0 (6a)
Ph (5a)
70 (6a; 1:50)
52 (6b; 1:8)
63 (6c; 1:20)
80 (6d; 1:30)
98 (6e; 1:50)
86 (6 f; 1:50)
76 (6g; 1:50)
77 (6h; 1:50)
90 (6i; 1:50)
93 (6j; 1:50)
4-MeOC6H4 (5b)
4-MeC6H4 (5c)
3-MeC6H4 (5d)
4-ClC6H4 (5e)
4-FC6H4 (5 f)
2-naphthyl (5g)
Ph (5a)
7
8
9
10
11
12
13
14
Et (1b)
Et (1b)
4-ClC6H4 (5e)
4-FC6H4 (5 f)
[a] All reactions of 1 (0.30 mmol) with 5 (1.5 mmol) and Sc(OTf)3
(0.75 mmol) were carried out in the presence of 3a (0.015 mmol) in
ClCH2CH2Cl (6 mL) at room temperature for 3 h. [b] Yield of isolated
product. [c] Determined by 1H NMR spectroscopy. [d] BF3·OEt2
(1.50 mmol; 5 equiv to 1a) was used in place of Sc(OTf)3. [e] Yield
determined by 1H NMR spectroscopy. [f] In the absence of 3a. [g] In the
absence of Sc(OTf)3. [h] 5a (0.75 mmol; 2.5 equiv to 1a) was used.
2
www.angewandte.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2013, 52, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
(2.5 equiv) in the presence of 5 mol% of 3a afforded dimethyl
5-ethynyl-2-phenyl-1-tosylpyrrolidine-3,3-dicarboxylate (6a)
in 88% yield as a mixture of two stereoisomers, with the
cis isomer being predominant (Table 3, entry 1). When
BF3·OEt2 was used in place of Sc(OTf)3, the yield of 6a
decreased dramatically (Table 3, entry 2). This decrease is due
to the difference in the coordination ability of BF3 versus that
of Sc(OTf)3. We confirmed that use of both Sc(OTf)3 and 3a is
necessary for producing 6a (Table 3, entries 3 and 4). The
reaction of 1a with 2.5 equivalents of 5a under the same
reaction conditions gave 6a in 70% yield with a similar
cis selectivity (Table 3, entry 5). Other reactions of 1 with
a variety of N-tosylaldimines (5) proceeded smoothly to give
the corresponding ethynylpyrrolidines (6) in high to excellent
yields with an excellent selectivity for cis isomers (Table 3,
entries 6–14).[19,20]
results in the formation of an allenylidene complex B, bearing
an enol moiety. Nucleophilic attack of B on 2a, which is
activated by BF3·OEt2, proceeds to afford a new allenylidene
complex (C) with subsequent intramolecular cyclization to
give a vinylidene complex D. Finally, a ligand exchange
reaction between D and another 1a occurs to give the
corresponding cycloaddition product 4a accompanied by
regeneration of A. We believe that the synergistic effect[21]
of the two ruthenium centers in the diruthenium complexes is
also quite important for promotion of this catalytic reaction
smoothly. Unfortunately, we have not yet observed the
formation of the allenylidene complex B as a reactive species
as it is considered to be too reactive to be isolated as an
intermediate, but the formation of vinylidene complexes A
and D can be confirmed by 1H NMR analysis of the reaction
mixture.[18]
A plausible reaction pathway is shown in Scheme 2. The
initial step is the formation of the ruthenium vinylidene
complex A by the reaction of 1a with 3. Isomerization of A
To gain insight into the reaction pathway, we carried out
the DFT calculations using the B3LYP hybrid functional with
Gaussian03 and 09 programs (LANL2DZ for Ru atom and 6-
31G* for other atoms)[18] for the model reaction of the
ruthenium vinylidene complex [CpRuCl(m2-SMe)2RuCp-
+
= =
( C CHCHCH2C(COOMe)2)] (I), which forms through
the reaction of the diruthenium complex [CpRuCl(m2-
SMe)2RuCp]+ with 1a, and the BF3-coordinated formalde-
hyde.[21] The Gibbs free-energy diagram is shown in Scheme 3.
Detailed reaction pathway and optimized structures are
shown in Figures S2 and S3, respectively, in the Supporting
Information.[18] The complexation between I and the BF3-
coordinated formaldehyde gives a weak reactant complex (II)
because of the electrostatic interaction between the cationic
system I and the electronegative fluorine atoms at BF3. The
free energy (DG) of II relative to the initial state (I + BF3-
coordinated formaldehyde), is + 3.4 kcalmolÀ1. The transfer
of the hydrogen atom from the b-carbon atom to the oxygen
atom in the ester group gives the complex III (DG =
+ 15.7 kcalmolÀ1) via the transition state TSI, and bond
Scheme 2. Proposed reaction pathway leading to cycloaddition
product.
Scheme 3. Relative Gibbs free-energy diagrams (kcalmolÀ1) for the model reactions in the gas phase at 298.15 K. Values in parentheses are
relative energies.
Angew. Chem. Int. Ed. 2013, 52, 1 – 6
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

.
Angewandte
Communications
cleavage between the g-carbon atom and the e-carbon atom
subsequently occurs via TSII to afford the allenylidene
complex IV (DG =+ 20.1 kcalmolÀ1). Then the nucleophilic
attack of the e-carbon atom in IV onto the carbonyl carbon
atom of formaldehyde, the electrophilicity of which is
strengthened by the coordination with the Lewis acid BF3,
occurs along with the interaction between the hydrogen atom
in the ester group and the fluorine atom in BF3 (TSIII) to
afford the complex V (DG =+ 6.3 kcalmolÀ1). The carbonyl
carbon atom of formaldehyde, which interacts with the
oxygen atom of the ester group in IV, now binds to the e-
carbon atom in V. The hydrogen atom in the ester group
which interacts tightly with the fluorine atom is easily
transferred onto the oxygen atom derived from formaldehyde
(TSIV) to afford the complex VI (DG = À9.4 kcalmolÀ1).
Another conformational structure (VII) with respect to VI
forms through TSV. Again the hydrogen atom which is
attached to the oxygen atom derived from formaldehyde is
transferred back to the b-carbon atom via TSVI to give the
complex VIII. In VIII, the weak interaction between the
hydrogen atom and the oxygen atom derived from formalde-
hyde still remains and is diminished through the transition-
state TSVII to form the complex IX. Finally, the oxygen atom
derived from formaldehyde attacks the g-carbon atom
(TSVIII) to afford the vinylidene complex X. The DG of X
is À17.0 kcalmolÀ1, which is much more stable than the initial
state. Thus the proposed pathway involving the ruthenium
allenylidene complex proceeds smoothly.
carboxy groups at the homopropargylic position, with alde-
hydes and aldimines leads to the corresponding 2-ethynyl-
tetrahydrofurans and pyrrolidines in high to excellent
yields.[22,23] The DFT calculations support the reaction path-
way which involves the ruthenium allenylidene complex as
a key intermediate. It is noted that the ruthenium allenylidene
reaction pathway differs from the pathway which has been
reported for the Lewis acid catalyzed cycloaddition of
aldehydes with donor–acceptor cyclopropanes.[24–27] We
believe that this finding will open up a new aspect of the
chemistry of metal allenylidene complexes which can be
accessed by a new approach, which differs from known
methods using propargylic alcohols and its derivatives.
Received: September 27, 2012
Revised: November 1, 2012
Published online: && &&, &&&&
Keywords: cycloaddition · density functional calculations ·
.
heterocycles · ruthenium · synthetic methods
[1] For recent reviews, see: a) C. Bruneau, P. H. Dixneuf, Angew.
Chem. 2006, 118, 2232; Angew. Chem. Int. Ed. 2006, 45, 2176;
b) R.-S. Liu, Synlett 2008, 801; c) V. Cadierno, J. Gimeno, Chem.
Rev. 2009, 109, 3512, and references therein.
[2] a) Y.-S. Yen, Y.-C. Lin, S.-L. Huang, Y.-H. Liu, H.-L. Sung, Y.
Wang, J. Am. Chem. Soc. 2005, 127, 18037; b) C.-W. Cheng, Y.-C.
Kuo, S.-H. Chang, Y.-C. Lin, Y.-H. Liu, Y. Wang, J. Am. Chem.
Soc. 2007, 129, 14974; c) M.-C. Lui, C.-P. Chung, W.-C. Chang,
Y.-C. Lin, Y. Wang, Y.-H. Liu, Organometallics 2009, 28, 5204;
d) C.-P. Chung, C.-C. Chen, Y.-C. Lin, Y.-H. Liu, Y. Wang, J. Am.
Chem. Soc. 2009, 131, 18366.
[3] a) E. Bustelo, M. Jimꢀnez-Tenorio, M. C. Puerta, P. Valerga,
Organometallics 2006, 25, 4019; b) E. Bustelo, M. Jimꢀnez-
Tenorio, M. C. Puerta, P. Valerga, Organometallics 2007, 26,
4300; c) J. A. Pino-Chamorro, E. Bustelo, M. C. Puerta, P.
Valerga, Organometallics 2009, 28, 1546.
[4] a) E. O. Fischer, H.-J. Kalder, A. Frank, F. H. Kçhler, G.
Huttner, Angew. Chem. 1976, 88, 683; Angew. Chem. Int. Ed.
Engl. 1976, 15, 623; b) H. Berke, Angew. Chem. 1976, 88, 684;
Angew. Chem. Int. Ed. Engl. 1976, 15, 624.
We also examined the concerted cycloaddition pathway in
which the BF3-coordinated formaldehyde directly attacks the
cyclopropane ring in the ruthenium vinylidene complex I
(Scheme 4).[18] The DG of the transition state for the
concerted pathway is + 37.1 kcalmolÀ1, which is much larger
than that of the transition states in the reaction pathway
which proceeds through the ruthenium allenylidene complex.
Therefore, the reaction pathway shown in Scheme 3 is
preferred to the concerted pathway.
In summary, we have found that the ruthenium-catalyzed
[3+2] cycloaddition of ethynylcyclopropanes, bearing two
[5] J. P. Selegue, Organometallics 1982, 1, 217.
[6] B. M. Trost, J. A. Flygare, J. Am. Chem. Soc. 1992, 114, 5476.
[7] Y. Nishibayashi, I. Wakiji, M. Hidai, J. Am. Chem. Soc. 2000, 122,
11019.
[8] For recent reviews of propargylic substitution reactions, see:
a) G. W. Kabalka, M. L. Yao, Curr. Org. Synth. 2008, 5, 28; b) N.
Ljungdahl, N. Kann, Angew. Chem. 2009, 121, 652; Angew.
Chem. Int. Ed. 2009, 48, 642; c) Y. Miyake, S. Uemura, Y.
Nishibayashi, ChemCatChem 2009, 1, 342; d) R. J. Detz, H.
Hiemstra, J. H. van Maarseveen, Eur. J. Org. Chem. 2009, 6263;
e) C.-H. Ding, X.-L. Hou, Chem. Rev. 2011, 111, 1914; f) Y.
Nishibayashi, Synthesis 2012, 489.
[9] a) Y. Nishibayashi, H. Imajima, G. Onodera, M. Hidai, S.
Uemura, Organometallics 2004, 23, 26; b) Y. Nishibayashi, H.
Imajima, G. Onodera, Y. Inada, M. Hidai, S. Uemura, Organo-
metallics 2004, 23, 5100.
[10] a) K. Fukamizu, Y. Miyake, Y. Nishibayashi, J. Am. Chem. Soc.
2008, 130, 10498; b) M. Ikeda, Y. Miyake, Y. Nishibayashi,
Angew. Chem. 2010, 122, 7447; Angew. Chem. Int. Ed. 2010, 49,
7289; c) M. Ikeda, Y. Miyake, Y. Nishibayashi, Chem. Eur. J.
2012, 18, 3321.
Scheme 4. Relative Gibbs free-energy diagrams (kcalmolÀ1) for the
model reactions in the gas phase at 298.15 K (I–TSII–IV–TSIII–X (gray
line): pathway via ruthenium allenylidene intermediate; I–TSIX–XII
(black line): concerted pathway). Values in parentheses are relative
energies.
[11] a) G. Hattori, H. Matsuzawa, Y. Miyake, Y. Nishibayashi,
Angew. Chem. 2008, 120, 3841; Angew. Chem. Int. Ed. 2008,
4
www.angewandte.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2013, 52, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
47, 3781; b) G. Hattori, K. Sakata, H. Matsuzawa, Y. Tanabe, Y.
Miyake, Y. Nishibayashi, J. Am. Chem. Soc. 2010, 132, 10592;
c) A. Yoshida, G. Hattori, Y. Miyake, Y. Nishibayashi, Org. Lett.
2011, 13, 2460.
[22] For reviews, see: a) H.-U. Reissig, R. Zimmer, Chem. Rev. 2003,
103, 1151; b) M. Yu, B. L. Pagenkopf, Tetrahedron 2005, 61, 321;
c) D. Agrawal, V. K. Yadav, Chem. Commun. 2008, 6471.
[23] Cycloaddition of 1a and 1b mediated by BF3·OEt2 and Sc(OTf)3
by using dicobalthexacarbonyl alkyne complexes has been
reported, see: a) S. D. R. Christie, R. J. Davoile, M. R. J. Else-
good, R. Fryatt, R. C. F. Jones, G. J. Pritchard, Chem. Commun.
2004, 2474; b) T. P. Lebold, C. A. Carson, M. A. Kerr, Synlett
2006, 364; c) S. D. R. Christie, R. J. Davoile, R. C. F. Jones, Org.
Biomol. Chem. 2006, 4, 2683.
[12] a) K.-L. Yeh, B. Liu, C.-Y. Lo, H.-L. Huang, R.-S. Liu, J. Am.
Chem. Soc. 2002, 124, 6510; b) S. Datta, C.-L. Chang, K.-L. Yeh,
R.-S. Liu, J. Am. Chem. Soc. 2003, 125, 9294; c) H.-C. Shen, H.-
L. Su, Y.-C. Hsueh, R.-S. Liu, Organometallics 2004, 23, 4332;
d) K.-L. Yeh, B. Liu, Y.-T. Lai, C.-W. Li, R.-S. Liu, J. Org. Chem.
2004, 69, 4692.
[24] a) P. D. Pohlhaus, J. S. Johnson, J. Org. Chem. 2005, 70, 1057;
b) P. D. Pohlhaus, J. S. Johnson, J. Am. Chem. Soc. 2005, 127,
16014; c) P. D. Pohlhaus, S. D. Sanders, A. T. Parsons, W. Li, J. S.
Johnson, J. Am. Chem. Soc. 2008, 130, 8642; d) M. J. Campbell,
J. S. Johnson, A. T. Parsons, P. D. Pohlhaus, S. D. Sanders, J. Org.
Chem. 2010, 75, 6317.
[25] For recent examples of reactions of donor–acceptor cyclo-
propanes, see: a) B. Bajtos, M. Yu, H. Zhao, B. L. Pagenkopf, J.
Am. Chem. Soc. 2007, 129, 9631; b) A. Karadeolian, M. A. Kerr,
J. Org. Chem. 2010, 75, 6830; c) M. M. A. R. Moustafa, B. L.
Pagenkopf, Org. Lett. 2010, 12, 3168; d) H. K. Grover, T. P.
Lebold, M. A. Kerr, Org. Lett. 2011, 13, 220, and references
therein.
[26] For the theoretical studies of cycloaddition of cyclopropane
using Lewis acids, see: a) D. Wanapun, K. A. Van Gorp, N. J.
Mosey, M. A. Kerr, T. K. Woo, Can. J. Chem. 2005, 83, 1752; b) J.
Zhang, W. Shen, M. Li, Eur. J. Org. Chem. 2007, 4855.
[27] For selected examples of [3+2] cyloaddition using cyclopropanes
as a three-carbon synthon, see: a) L. Jiao, S. Ye, Z.-X. Yu, J. Am.
Chem. Soc. 2008, 130, 7178; b) Q. Li, G.-J. Jiang, L. Jiao, Z.-X.
Yu, Org. Lett. 2010, 12, 1332; c) L. Jiao, M. Lin, L.-G. Zhuo, Z.-
X. Yu, Org. Lett. 2010, 12, 2528; d) L. Jiao, M. Lin, Z.-X. Yu,
Chem. Commun. 2010, 46, 1059; e) H.-S. Yeom, J. Koo, H.-S.
Park, Y. Wang, Y. Liang, Z.-X. Yu, S. Shin, J. Am. Chem. Soc.
2012, 134, 208; f) Z. Lu, M. Shen, T. P. Yoon, J. Am. Chem. Soc.
2011, 133, 1162; g) S. Maity, M. Zhu, R. S. Shinabery, N. Zheng,
Angew. Chem. 2012, 124, 226; Angew. Chem. Int. Ed. 2012, 51,
222, and references therein.
[13] a) V. Cadierno, J. Dꢁez, S. E. Garcꢁa-Garrido, J. Gimeno, Chem.
Commun. 2004, 2716; b) V. Cadierno, S. E. Garcꢁa-Garrido, J.
Gimeno, Adv. Synth. Catal. 2006, 348, 101.
[14] a) R. J. Detz, M. M. E. Delville, H. Hiemstra, J. H. van Maar-
seveen, Angew. Chem. 2008, 120, 3837; Angew. Chem. Int. Ed.
2008, 47, 3777; b) R. J. Detz, Z. Abiri, R. le Griel, H. Hiemstra,
J. H. van Maarseveen, Chem. Eur. J. 2011, 17, 5921.
[15] a) P. Fang, X.-L. Hou, Org. Lett. 2009, 11, 4612; b) C. Zhang, X.-
H. Hu, Y.-H. Wang, Z. Zheng, J. Xu, X.-P. Hu, J. Am. Chem. Soc.
2012, 134, 9585; c) C. Zhang, Y.-H. Wang, X.-H. Hu, Z. Zheng, J.
Xu, X.-P. Hu, Adv. Synth. Catal. 2012, 354, 2854.
[16] a) S. Dev, K. Imagawa, Y. Mizobe, G. Cheng, Y. Wakatsuki, H.
Yamazaki, M. Hidai, Organometallics 1989, 8, 1232; b) J.-P. Qꢂ,
D. Masui, Y. Ishii, M. Hidai, Chem. Lett. 1998, 1003; c) M. Hidai,
Y. Mizobe, Can. J. Chem. 2005, 83, 358, and references therein.
[17] The stereoisomers of trans- and cis-4a were confirmed by NOE
measurements.
[18] See the Supporting Information for experimental details.
[19] The molecular structure of cis-6e was confirmed by X-ray
analysis. See the Supporting Information for experimental
details.
[20] The origin of stereoselectivity is described in the Supporting
Information.
[21] a) S. C. Ammal, N. Yoshikai, Y. Inada, Y. Nishibayashi, E.
Nakamura, J. Am. Chem. Soc. 2005, 127, 9428; b) K. Sakata, Y.
Miyake, Y. Nishibayashi, Chem. Asian J. 2009, 4, 81.
Angew. Chem. Int. Ed. 2013, 52, 1 – 6
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

.
Angewandte
Communications
Communications
Synthetic Methods
Y. Miyake, S. Endo, T. Moriyama,
K. Sakata,*
Y. Nishibayashi*
&&& — &&&
Ruthenium-Triggered Ring Opening of
Ethynylcyclopropanes: [3+2]
Cycloaddition with Aldehydes and
Aldimines Involving Metal Allenylidene
Intermediates
It’s complex: Ruthenium-catalyzed [3+2]
cycloaddition of ethynylcyclopropanes
with aldehydes and aldimines has been
found to give the corresponding 2-ethy-
nyltetrahydrofurans or -pyrrolidines in
high to excellent yields. In both cases, the
formation of a ruthenium allenylidene
complex as a key reactive intermediate is
supported by density functional theory
calculations. Cp*=h5-C5Me5.
6
www.angewandte.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2013, 52, 1 – 6
These are not the final page numbers!