Catalytic Cyclopropanation of Alkenes via (2-Furyl)carbene Complexes from 1-Benzoyl-cis-1-buten-3-yne with Transition Metal Compounds

Article abstract of DOI:10.1021/jo0352732

The reaction of alkenes with conjugated ene-yne-ketones, such as 1-benzoyl-2-ethynylcycloalkenes, with a catalytic amount of Cr(CO) ₅(THF) gave 5-phenyl-2-furylcyclopropane derivatives in good yields. The key intermediate of this cyclopropanation is a (2-furyl)carbene complex generated by a nucleophilic attack of carbonyl oxygen to an internal alkyne carbon in π-alkyne complex or σ-vinyl cationic complex. A wide range of late transition metal compounds, such as [RuCl₂(CO) ₃]₂, [RhCl-(cod)]₂, [Rh(OAc)₂] ₂, PdCl₂, and PtCl₂, also catalyzes the cyclopropanation of alkenes with ene-yne-ketones effectively. When the reactions were carried out with dienes as a carbene acceptor, the more substituted or more electron-rich alkene moiety was selectively cyclopropanated with the (2-furyl)carbenoid intermediate.

Full text of DOI:10.1021/jo0352732

Ca ta lytic Cyclop r op a n a tion of Alk en es via (2-F u r yl)ca r ben e
Com p lexes fr om 1-Ben zoyl-cis-1-bu ten -3-yn e w ith Tr a n sition Meta l
Com p ou n d s
Koji Miki, Tomomi Yokoi, Fumiaki Nishino, Yumiko Kato, Yosuke Washitake,
Kouichi Ohe,* and Sakae Uemura*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University,
Sakyo-ku, Kyoto 606-8501, J apan
ohe@scl.kyoto-u.ac.jp; uemura@scl.kyoto-u.ac.jp
Received August 31, 2003
The reaction of alkenes with conjugated ene-yne-ketones, such as 1-benzoyl-2-ethynylcycloalkenes,
with a catalytic amount of Cr(CO)5(THF) gave 5-phenyl-2-furylcyclopropane derivatives in good
yields. The key intermediate of this cyclopropanation is a (2-furyl)carbene complex generated by a
nucleophilic attack of carbonyl oxygen to an internal alkyne carbon in π-alkyne complex or σ-vinyl
cationic complex. A wide range of late transition metal compounds, such as [RuCl2(CO)3]2, [RhCl-
(cod)]2, [Rh(OAc)2]2, PdCl2, and PtCl2, also catalyzes the cyclopropanation of alkenes with ene-yne-
ketones effectively. When the reactions were carried out with dienes as a carbene acceptor, the
more substituted or more electron-rich alkene moiety was selectively cyclopropanated with the
(2-furyl)carbenoid intermediate.
In tr od u ction
been recognized as new entries to metal carbenoids from
alkynes. We have already reported electrocyclization of
vinylidene intermediates generated from ene-yne-esters
or -amides 1 (R ) OR′ or R ) NR′′2) with group 6
transition metal complexes leading to 2-pyranylidene
complexes 2 (Scheme 1a)9 and valence isomerization of
1-acyl-2-ethynylcyclopropanes 3 via [3,3]sigmatropy of
acylcyclopropylvinylidene intermediates catalyzed by
Carbenoid species generated from diazoalkanes and
transition metal complexes have been used for a wide
range of carbene transfer reactions.1 Diazo decomposition
by transition metal complexes is often a useful but
formidable task due to the explosive hazard and a
number of unfavorable side reactions, such as diazo
dimerization and azine formation. To circumvent such
difficulties, safe alternatives to handling diazoalkanes or
special techniques involving slow addition of them are
required. Recently, much attention has been paid to
activation of alkynes with transition metal compounds
as a safe and facile alternative to diazo decomposition.
Cyclopropylcarbenoid in skeletal reorganization of R,ω-
enynes,2,3 dialkylidene ruthenium species from ω-diynes,4
transition metal-containing carbonyl ylides from o-ethy-
nylphenylcarbonyl compounds,5,6 copper-(isoindazolyl)-
carbenoids from (2-ethynylphenyl)triazenes,7 and vinyl-
carbenoids from propargylic carboxylates8 have so far
(3) The reactions of R,ω-enynes with dienes via cyclopropylcarbene
complexes have been reported. See: (a) Trost, B. M.; Hashmi, A. S. K.
Angew. Chem., Int. Ed. Engl. 1993, 32, 1085. (b) Trost, B. M.; Hashmi,
A. S. K. J . Am. Chem. Soc. 1994, 116, 2183. The reactions of R,ω-enynes
with alcohols or alkynes with furans via cyclopropylcarbene complexes.
See: (c) Me´ndez, M.; Mun˜oz, M. P.; Echavarren, A. M. J . Am. Chem.
Soc. 2000, 122, 11549. (d) Me´ndez, M.; Mun˜oz, M. P.; Nevado, C.;
Ca´rdenas, D. J .; Echavarren, A. M. J . Am. Chem. Soc. 2001, 123,
10511. (e) Ferna´ndez-Rivas, C.; Me´ndez, M.; Nieto-Oberhuber, C.;
Echavarren, A. M. J . Org. Chem. 2002, 67, 5197. (f) Mart´ın-Matute,
B.; Nevado, C.; Ca´rdenas, D. J .; Echavarren, A. M. J . Am. Chem. Soc.
2003, 125, 5757.
(4) Yamamoto, Y.; Kitahara, H.; Ogawa, R.; Kawaguchi, H.; Tatsumi,
K.; Itoh, K. J . Am. Chem. Soc. 2000, 122, 4310.
(5) (a) Iwasawa, N.; Shido, M.; Kusama, H. J . Am. Chem. Soc. 2001,
123, 5814. For an example of the azomethine ylide, see: (b) Kusama,
H.; Takaya, J .; Iwasawa, N. J . Am. Chem. Soc. 2002, 124, 11592.
(6) Asao, N.; Takahashi, K.; Lee, S.; Kasahara, T.; Yamamoto, Y. J .
Am. Chem. Soc. 2002, 124, 12650.
(7) (a) Kimball, D. B.; Herges, R.; Haley, M. M. J . Am. Chem. Soc.
2002, 124, 1572. (b) Kimball, D. B.; Weakley, T. J . R.; Herges, R.; Haley,
M. M. J . Org. Chem. 2002, 67, 6395. (c) Kimball, D. B.; Weakley, T. J .
R.; Herges, R.; Haley, M. M. J . Am. Chem. Soc. 2002, 124, 13463. (d)
Kimball, D. B.; Haley, M. M. Angew. Chem., Int. Ed. 2002, 41, 3339.
(8) (a) Rautenstrauch, V. Tetrahedron Lett. 1984, 25, 3845. (b)
Rautenstrauch, V. J . Org. Chem. 1984, 49, 950. (c) Mainett, E.;
Mourie`s, V.; Fensterbank, L.; Malacria, M.; Marco-Contelles, J . Angew.
Chem., Int. Ed. 2002, 41, 2132. (d) Miki, K.; Ohe, K.; Uemura, S.
Tetrahedron Lett. 2003, 44, 2019. (e) Miki, K.; Ohe, K.; Uemura, S. J .
Org. Chem. 2003, 68, 8505. Oxidative rearrangement of propargyl
esters by palladium catalyst has been reported, see: (f) Kataoka, H.;
Watanabe, K.; Goto, K. Tetrahedron Lett. 1990, 31, 4181.
(1) (a) Hegedus, L. S. Transition Metals in the Synthesis of Complex
Organic Molecules, 2nd ed.; University Science Books: Mill Valley,
CA, 1999; p 143. (b) Doyle, M. P. In Comprehensive Organometallic
Chemistry II; Hegedus, L. S., Ed.; Pergamon: Oxford, 1995; Vol. 12,
pp 421-468. (c) Doyle, M. P.; Forbes, D. C. Chem. Rev. 1998, 98, 911.
(d) Padwa, A.; Weingarten, M. D. Chem. Rev. 1996, 96, 223. (e) Ye, T.;
McKervey, M. A. Chem. Rev. 1994, 94, 1091.
(2) Transition metal-catalyzed reorganization reaction of enynes. For
example, [Pd] cat.: (a) Trost, B. M.; Tanoury, G. J . J . Am. Chem. Soc.
1988, 110, 1636. (b) Trost, B. M.; Trost, M. K. Tetrahedron Lett. 1991,
32, 3647. (c) Trost, B. M.; Trost, M. K. J . Am. Chem. Soc. 1991, 113,
1850. [Ru] cat.: (d) Chatani, N.; Morimoto, T.; Muto, T.; Murai, S. J .
Am. Chem. Soc. 1994, 116, 6049. [Ru] or [Pt] cat.: (e) Chatani, N.;
Kataoka, K.; Murai, S.; Furukawa, N.; Seki, Y. J . Am. Chem. Soc. 1998,
120, 9140. (f) Chatani, N.; Inoue, H.; Ikeda, T.; Murai, S. J . Org. Chem.
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Murai, S. Organometallics 1996, 15, 901. (h) Oi, S.; Tsukamoto, I.;
Miyano, S.; Inoue, Y. Organometallics 2001, 20, 3704. [Ir] cat.: (i)
Chatani, N.; Inoue, H.; Morimoto, T.; Muto, T.; Murai, S. J . Org. Chem.
2001, 66, 4433.
(9) Ohe, K.; Miki, K.; Yokoi, T.; Nishino, F.; Uemura, S. Organo-
metallics 2000, 19, 5525. For benzopyranylidene complexes, see:
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2000, 122, 10226.
10.1021/jo0352732 CCC: $27.50 © 2004 American Chemical Society
Published on Web 02/05/2004
J . Org. Chem. 2004, 69, 1557-1564
1557

Miki et al.
SCHEME 1
SCHEME 2
Resu lts a n d Discu ssion
Ch r om iu m -Ca ta lyzed Cyclop r op a n a tion of Alk -
en es. At first, the reaction of 4a with 2 equiv of tert-
butyl vinyl ether was carried out in the presence of 5 mol
% of Cr(CO)5(THF) at room temperature (eq 1). The color
of the reaction mixture gradually changed from deep blue
to yellow as the reaction proceeded.16 After 2 h, 1-tert-
butoxy-2-[(5-phenyl)fur-2-yl]cyclopropane (6a) was isolated
in 63% yield as a mixture of cis and trans isomers
(cis:trans ) 76:24). As shown in eq 2, similar eneyne-ke-
tones 4b and 4c also afforded the corresponding cyclo-
propanated products 6b (62% yield, cis:trans ) 62:38) and
6c (90% yield, cis:trans ) 60:40), respectively.17
group 6 transition metal complexes (Scheme 1b).10 We
also demonstrated the formation of stable (2-furyl)-
carbene-chromium or -tungsten complexes 5 from ene-
yne-ketones 4 (R ) Ar) (Scheme 1c).11 The key of the third
reaction is 5-exo-dig cyclization via nucleophilic attack
of a carbonyl oxygen to an internal carbon of an alkyne
moiety activated by transition metal complexes. Furyl-
carbene complexes 5 were somewhat more stable than
the corresponding phenylcarbene complexes,12 which
could be stoichiometrically generated and used in cyclo-
propanation reactions.13 Our continuous work mainly
focusing on the catalytic activity of 5 led us to find new
catalytic cyclopropanation via (2-furyl)carbene complexes
without using the corresponding diazoalkane as a pre-
cursor.14 Cyclopropanation with (2-furyl)diazomethane
was scarcely investigated due to the instability of the (2-
furyl)carbene intermediate.15
In this paper, we wish to report the details and the
scope of the cyclopropanation reaction involving (2-furyl)-
carbene complexes 5 directly generated from ene-yne-
ketones 4 with a wide range of transition metal com-
pounds (Scheme 2).
The reaction of ethyl ketone 4d with tert-butyl vinyl
ether was quite complex and many unidentified products
formed, reducing the yield of cyclopropanated product 6d
to 20-30%. To our knowledge, examples of chromium-
catalyzed cyclopropanation have been thus far limited to
reports by Do¨tz et al.18 Since the chromium-catalyzed
cyclopropanation with ene-yne-ketones as carbenoid pre-
cursors was efficiently delineated, cyclopropanations of
several alkenes with 4a and 4c were next examined.
Typical results are given in Table 1. Reactions of 4a and
4c with ketene diethyl acetal proceeded quite smoothly
to give furylcyclopropanes 7a (82%) and 7c (99%),
respectively (entries 1 and 2). Ene-yne-ketone 4c also
reacted with enol silyl ether to give 8c in 83% yield with
a 66:34 diastereomeric ratio (entry 3). Interestingly, the
reaction of 4c with 3,4-dihydro-2H-pyran as a cyclic vinyl
ether exclusively gave endo cyclopropanated product 9c
(10) Ohe, K.; Yokoi, T.; Miki, K.; Nishino, F.; Uemura, S. J . Am.
Chem. Soc. 2002, 124, 526.
(11) Miki, K.; Yokoi, T.; Nishino, F.; Ohe, K.; Uemura, S. J .
Organomet. Chem. 2002, 645, 228. For 6-endo-dig cyclization of
2-acylethynylbenzene with W(CO)5(THF) complex, see: Iwasawa, N.;
Shido, M.; Kusama, H. J . Am. Chem. Soc. 2001, 123, 5814.
(12) (a) Casey, C. P.; Polichnowski, S. W. J . Am. Chem. Soc. 1977,
99, 6097. (b) Brookhart, M.; Nelson, G. O. J . Am. Chem. Soc. 1977,
99, 6099. (c) Casey, C. P.; Polichnowski, S. W.; Shusterman, A. J .;
J ones, C. R. J . Am. Chem. Soc. 1979, 101, 7282. (d) Brookhart, M.;
Humphrey, M. B.; Kratzer, H. J .; Nelson, G. O. J . Am. Chem. Soc.
1980, 102, 7802. (e) Doyle, M. P.; Griffin, J . H.; Bagheri, V.; Dorow, R.
L. Organometallics 1984, 3, 53. (f) Fischer, H.; Zeuner, S.; Ackermann,
K. J . Chem. Soc., Chem. Commun. 1984, 684. (g) Fischer, H.; Hofmann,
J . Chem. Ber. 1991, 124, 981. (h) Casey, C. P.; Vosejpka, L. J . S
Organometallics 1992, 11, 738. (i) Fischer, H.; Mauz, E.; J aeger, M. J .
Organomet. Chem. 1992, 427, 63. (j) J aeger, M.; Prosenc, M.-H.; Sontag,
C.; Fischer, H. New J . Chem. 1995, 19, 911.
(13) (a) Brookhart, M.; Studabaker, W. B. Chem. Rev. 1987, 87, 411.
(b) Helquist, P. In Advances in Metal-Organic Chemistry; Liebeskind,
L. S., Ed.; J AI Press: London, UK, 1991; Vol. 2, pp 143-194. (c) Doyle,
M. P. In Comprehensive Organometallic Chemistry II; Hegedus, L. S.,
Ed.; Pergamon: Oxford, UK, 1995; Vol. 12, pp 387-420.
(16) The blue color indicates the generation of a (2-furyl)carbene
chromium complex. Thus, consumption of the starting material 4 could
be visibly monitored.
(17) When the reaction with a catalytic amount of Cr(CO)6 instead
of Cr(CO)5(THF) was conducted under thermal (reflux in THF for 24
h) or photoirradiation (in toluene for 2 h) conditions, the yield of 6c
was lower than that obtained by use of Cr(CO)5(THF), being in 10%
and 32% yields, respectively, with a similar diastereoselectivity.
(18) Catalytic approach for a 9-(9H-fluorenylidene)chromium com-
plex, see: (a) Pfeiffer, J .; Do¨tz, K. H. Angew. Chem., Int. Ed. Engl.
1997, 36, 2828. (b) Pfeiffer, J .; Nieger, M.; Do¨tz, K. H. Eur. J . Org.
Chem. 1998, 1011.
(14) Preliminary communication of catalytic cyclopropanation with
ene-yne-carbonyl compounds. See: Miki, K.; Nishino, F.; Ohe, K.;
Uemura, S. J . Am. Chem. Soc. 2002, 124, 5260.
(15) (a) Hoffman, R. V.; Shechter, H. J . Am. Chem. Soc. 1971, 93,
5940. (b) Hoffman, R. V.; Orphanides, G. G.; Shechter, H. J . Am. Chem.
Soc. 1978, 100, 7927. (c) Khasanova, T.; Sheridan, R. S. J . Am. Chem.
Soc. 2000, 122, 8585.
1558 J . Org. Chem., Vol. 69, No. 5, 2004

Catalytic Cyclopropanation of Alkenes
TABLE 1. Ch r om iu m -Ca ta lyzed Cyclop r op a n a tion of
Alk en es w ith 4a
SCHEME 3
SCHEME 4
a
Reactions were carried out at room temperature with 4 (0.5
mmol), alkene (1.0 mmol), and Cr(CO)5(THF) prepared in situ by
irradiating a solution of Cr(CO)6 (0.025 mmol) in THF (2 mL)
unless otherwise noted. Determined by 1H NMR. c N.A. ) not
b
d
applicable. Configuration is not yet clear. e Alkene (10 mmol).
panation, the slow addition of 4 is not always required
in the present cyclopropanation reaction.
f 2-Ethylbut-1-ene (7.5 mmol).
Oth er Tr a n sition Meta l-Ca ta lyzed Cyclop r op a -
n a tion of Alk en es. As shown in Scheme 4, 5-exo-dig
cyclization of ene-yne-ketone 410 via nucleophilic attack
of a carbonyl oxygen to an internal carbon of an alkyne
in π-alkyne complex A might be the most plausible
pathway for generation of (2-furyl)carbene-chromium
complex 5 (M ) Cr(CO)5). A slipped and polarized
η1-complex B from complex A would be an alternatively
possible intermediate. It is well-known that A is prone
to isomerize to B, which has been widely accepted for an
intermediate for cyclization and skeletal reorganization
of 1,6-enynes with a diversity of metal complexes.2,3
Considering the possibility of the intervention of B, we
examined cyclopropanation of styrene with 4c in the
presence of other transition metal compounds as catalysts
(Table 2). Other group 6 metal complexes such as Mo-
(CO)5(THF) and W(CO)5(THF) were found to catalyze the
cyclopropanation to give 10c in 23% and 54% yields with
54:46 and 70:30 cis and trans ratios, respectively (entries
1 and 2). Mn(CO)5Br of the group 7 triad was marginally
effective in the cyclopropanation reaction (entry 3). Of
in 90% yield (entry 4).19 Styrene reacted slowly with 4c
to give 10c (85%, cis:trans ) 74:26), although the reaction
required 20 equiv of styrene (entry 5). In the cyclopro-
panation of 2-ethylbut-1-ene with 4c, both prolonged
reaction time (96 h) and excess use of alkenes (12.5 eqiuv
to 4c) were requisite, the product 11c being produced in
52% yield (entry 6). On the other hand, cyclopropanation
of vinyl acetate and 1-octene with 4c was sluggish, the
yields of the corresponding cyclopropanated products
being 22% (6 days) and 19% (10 days), respectively. Here,
the complete consumption of the starting ene-yne-ketone
4c was observed, indicating that other reactions cata-
lyzed by chromium compete with the cyclopropanation
reaction. In fact, treatment of 4c in THF without an
alkene in the presence of a catalytic amount of Cr(CO)5-
(THF) yielded 1,2-difurylethene 12 in 87% yield with high
trans stereoselectivity for 60 h. The plausible mechanism
giving 12 is considered to be similar to the one proposed
by Herndon et al. (Scheme 3).20 Since the side reaction
occurs more slowly compared with the desired cyclopro-
(20) Furan ring construction from enyne-aldehyde derivatives with
a
stoichiometric amount of Fischer carbene complexes has been
(19) The structure was unambiguously determined by X-ray dif-
fraction analysis of 9c. See the Supporting Information.
demonstrated. See: (a) Herndon, J . W.; Wang, H. J . Org. Chem. 1998,
63, 4564. (b) Zhang, Y.; Herndon, J . W. J . Org. Chem. 2002, 67, 4177.
J . Org. Chem, Vol. 69, No. 5, 2004 1559

Miki et al.
TABLE 2. Ca ta lytic Cyclop r op a n a tion of Styr en e w ith
1ca
TABLE 3. Rh - or P t-Ca ta lyzed Cyclop r op a n a tion of
Alk en es w ith 4a
entry
catalyst
time, h
yield,b %
cis/transc
1
2
3
4
5
6
7
8
9
Mo(CO)5(THF)d
W(CO)5(THF)d
Mn(CO)5Br
2
2
24
2
24
1
2
2
2
1
23
54
21
85
42
93
69
92
79
81
54:46
70:30
9:91
33:67
12:88
8:92
56:44
57:43
21:79
23:77
e
[(p-cymene)RuCl2]2
e
[RuCl2(CO)3]2
e,f
[Rh(OAc)2]2
a
[RhCl(cod)]2
e
[IrCl(cod)]2
PdCl2
PtCl2
10
a
Reactions were carried out at room temperature with 4c (0.20
mmol), styrene (4.0 mmol), and a catalyst (0.010 mmol) in THF (2
b
mL) unless otherwise noted. Isolated yield. c Determined by 1H
d
NMR. Prepared in situ by irradiating a solution of M(CO)6 in
THF. e 0.005 mmol. f Styrene (0.40 mmol).
a
Reactions were carried out at room temperature with 4 (0.2
group 8 triad metals, ruthenium complexes such as [(p-
cymene)RuCl2]2 and [RuCl2(CO)3]2 were effective to give
10c in 85% (cis:trans ) 33:67) and 42% (cis:trans ) 12:
88) yields, respectively (entries 4 and 5).21 Rhodium and
iridium complexes of the group 9 triad exhibited high
catalytic efficiency in the present reaction (entries 6-8).
In particular, [Rh(OAc)2]2 catalyzed the cyclopropanation
of 2 equiv of styrene with 4c to give 10c for 1 h with
exquisite efficiency (93% yield) and selectivity (cis:trans
) 8:92) (entry 6). PdCl2 and PtCl2 of the group 10 triad
effectively catalyzed the cyclopropanation of styrene to
give 10c in 79% (21:79 ratio) and 81% yields (23:77 ratio),
respectively (entries 9 and 10). Other metal compounds
such as Cp2Ti(isobutylene), Mn(acac)2, NiCl2, CuOTf-
(1/2C6H6), Cu(OTf)2, and AuCl3 were not effective as
catalysts in the present cyclopropanation. Variable ste-
reoselectivity obtained in these reactions indicates that
cyclopropanation proceeds in a different manner depend-
ing on each catalyst. The stereochemistry of the present
cyclopropanation reaction will be argued in the last
section (vide infra).
mmol), alkene (0.4 mmol), and [Rh(OAc)2]2 (0.005 mmol) or PtCl2
b
(0.01 mmol) in THF (2 mL) for 1 h unless otherwise noted. [Rh]
) [Rh(OAc)2]2, [Pt] ) PtCl2. c Isolated yield. Determined by 1H
d
NMR. e N.A. ) not applicable. f Styrene (4.0 mmol). 3 h.
g
effective catalyst in cyclopropanation of tert-butyl vinyl
ether with ethyl ketone 4d (eq 3), which led to a lower
yield of cyclopropanated product in chromium catalysis
(<30% yield, see eq 2).
Regioselectivity a n d Ch em oselectivity in Ca ta -
lytic Cyclop r op a n a tion . The pronounced preference for
the cyclopropanation reaction to take place at electron-
rich CdC bonds was verified by the chromium-, rhodium-,
and platinum-catalyzed reaction of 4 with isoprene and
2-vinyloxyethyl acrylate as shown in eqs 4-6. In each
reaction of isoprene with 4a and 4c, a more substituted
double bond was selectively cyclopropanated to give 13a
and 13c in good yields with nondiastereoselective man-
ner, respectively (eqs 4 and 5). As shown in eq 6, a more
electron-rich CdC double bond of 2-vinyloxyethyl acrylate
was selectively cyclopropanated to give 14c (73% with
[Cr], 92% with [Rh], and 46% with [Pt]) as a mixture of
diastereoisomers (67:33 to 90:10), respectively. A higher
reactivity of electron-rich alkenes and preferential forma-
tion of cis-cyclopropanes in this reaction indicate that the
cyclopropanation proceeds through the formation of an
electrophilic (2-furyl)carbenoid intermediate like phenyl-
carbene-tungsten and -iron complexes.12,13
To compare the chromium catalysis with other transi-
tion metal catalysts, we next examined cyclopropanation
of several alkenes with ene-yne-ketones 4a -c in the
presence of [Rh(OAc)2]2 and PtCl2 as selected catalysts.
These results are summarized in Table 3. The reactions
of 4a -c with tert-butyl vinyl ether, ketene diethyl acetal,
cyclic vinyl ether, and styrene proceeded quite smoothly
to give the cyclopropanated products 6a -c, 7c, 9c, and
10c in good yields, respectively (entries 1-11). In the
presence of [Rh(OAc)2]2 as a catalyst, the cyclopropana-
tion of 2-ethylbut-1-ene with 4c gave 11c in 67% yield
(entry 12), while a similar reaction with PtCl2 catalyst
gave 11c in only 18% yield together with other unidenti-
fied products (entry 13). [Rh(OAc)2]2 can act as an
P la u sible Rea ction P a th w a y. To elucidate the reac-
tion pathway, cyclopropanation of stereodefined cis- and
trans-but-2-ene was examined. In the presence of
Cr(CO)5(THF) and PtCl2 as selected catalysts, the cyclo-
propanation reaction of cis- and trans-but-2-ene with an
(21) In the case of [(p-cymene)RuCl2]2, a remarkable solvent effect
was observed. Thus, the use of ClCH2CH2Cl in place of THF as solvent
led to the rapid formation of the cyclopropanated product 10c in 96%
yield in the reaction of styrene with 4c at room temperature for 1 h
with a high trans selectivity (cis:trans ) 11:89).
1560 J . Org. Chem., Vol. 69, No. 5, 2004

Catalytic Cyclopropanation of Alkenes
SCHEME 5
SCHEME 6
ene-yne-ketone 4a proceeded stereospecifically to give
only the cyclopropanated products with retention of
configuration of alkenes, 15a (14%, syn:anti ) 91:9 with
[Cr]; 26%, syn:anti ) 75:25 with [Pt]) and 16a (7% with
[Cr]; 23% with [Pt]), respectively (eqs 7 and 8).22
ometry) except for the styrene case with [Rh(OAc)2]2.23
In the case of the late transition metals having the
square-planar geometry, the diastereoselectivity depends
considerably on the structure of alkenes and the stability
of metallacycles. The logical contention about the rela-
tionship between plausible intermediates and stereose-
lectivity of cyclopropanation still remains, but at least a
carbocationic intermediate E can be presumably excluded
in the present reaction.
Con clu sion
We have demonstrated new catalytic cyclopropanation
of alkenes based on the generation of (2-furyl)carbene
complexes from conjugated ene-yne-ketones. This cata-
lytic system has wide applicability to a diversity of
transition metal complexes as well as a variety of ene-
yne-ketones, and indeed finds some applications in other
catalytic 2-furfurylidene transfer reactions such as the
Doyle-Kirmse reaction.24 This reaction represents a new
protocol to generate carbenoid species via activation of
alkynes with transition metal complexes.
The outcomes of the stereochemistry show that the
most plausible reaction pathway for cyclopropanation of
an alkene with an ene-yne-ketone 4 is illustrated as
Scheme 5. The ene-yne-ketone 4 reacts with a transition
metal complex to give a (2-furyl)carbene complex 5 as
shown in Scheme 4. Subsequently, the complex 5 reacts
with an alkene to give the cyclopropanated product
through a metallacyclobutane C or a charge-developed
intermediate D.12a,c,h,j,13 The preference for the cis-cyclo-
propane isomer is a characteristic feature of the electro-
philic metal-carbenoid having the same or similar steric
environment (Cr(CO)5 or [Rh(OAc)2]2 in octahedral ge-
Exp er im en ta l Section
Syn th esis of Su bstr a tes. Substrates 4a 14 and 4c11 were
prepared by our reported procedures. Substrates 4b and 4d
were prepared from ene-yne-carbonyl compound 1711 by the
following procedures (Scheme 6).
1-Eth yn yl-2-ben zoylcyclop en t-1-en e (4b). To a solution
of 17 (1.2 g, 4.4 mmol, n ) 1) in THF (10 mL) was added
PhMgBr (9 mL, 9.0 mmol, 1.0 M in THF) at 0 °C. The mixture
(23) Cis preference was observed in the cyclopropanation of styrene
with PhCHN2 as a carbenoid precursor, the ratio of cis:trans being
77:23. See ref 12e.
(24) Kato, Y.; Miki, K.; Nishino, F.; Ohe, K.; Uemura, S. Org. Lett.
2003, 5, 2619.
(22) Lower yields of cyclopropanated products were due to the
formation of either 1,2-difurylethene 12 in the Cr-catalyzed reaction
or many unidentified products in the Pt-catalyzed reaction.
J . Org. Chem, Vol. 69, No. 5, 2004 1561

Miki et al.
was stirred at room temperature for 30 min. The mixture was
washed with saturated NH4Cl solution (10 mL) and the
aqueous phase was extracted with AcOEt (3 × 10 mL). The
combined organic phase was dried over MgSO4. The organic
solvent was removed under reduced pressure, and the residue
was subjected to column chromatography on SiO2 with hexane/
AcOEt (v/v 10/1) as an eluent to afford the crude ene-yne-
carbonyl compound (0.56 mg, 2.4 mmol, 54%) as a pale yellow
oil. To a solution of this crude ene-yne-carbonyl compound in
MeOH (20 mL) was added K2CO3 (0.66 g, 4.8 mmol) at room
temperature. After being stirred for 30 min, the suspension
was poured into a mixture of saturated aqueous NH4Cl
solution (30 mL) and Et2O (30 mL), and the aqueous phase
was extracted with Et2O (3 × 10 mL). The combined organic
phase was dried over MgSO4. The solvent was removed under
reduced pressure, and the residue was subjected to column
chromatography on SiO2 with hexane/AcOEt (v/v 15/1) as an
eluent to afford ene-yne-carbonyl compound 4b (0.35 g, 2.2
mmol, 64% yield for 2 steps) as a pale yellow oil; IR (neat)
1H), 7.14 (dd, J ) 7.6, 7.6 Hz, 1H), 7.30 (dd, J ) 7.6, 7.6 Hz,
2H), 7.58 (d, J ) 7.6 Hz, 2H);
13C NMR (100 MHz, d8-THF, 25
°C) cis isomer, δ 12.9, 17.3, 28.2, 52.4, 75.0, 106.6, 107.7, 123.7,
127.0, 129.2, 132.3, 152.5, 154.6; 13C NMR (100 MHz, d8-THF,
25 °C) trans isomer, δ 14.1, 19.1, 28.6, 54.2, 75.4, 106.5, 106.6,
123.8, 127.3, 129.2, 132.1, 152.8, 155.9. HRMS (FAB) calcd
for
C
17H20O2 (a mixture of cis and trans isomers) (M+)
256.1463, found 256.1463. Anal. Calcd for C17H20O2 (a mixture
of cis and trans isomers): C, 79.65; H, 7.86. Found: C, 79.75;
H, 8.01.
Cyclop r op a n e 6b (by [Rh ] Ca ta lyst). A colorless oil (55
mg, 0.18 mmol, 92%, cis/trans ) 85/15); IR (neat) 692, 761,
894, 922, 1010, 1024, 1190, 1363, 1389, 1494, 1604, 2973 cm-1
;
1H NMR (400 MHz, d8-THF, 25 °C) cis isomer, δ 0.96-1.10 (m,
2H), 1.08 (s, 9H), 1.89 (ddd, J ) 6.4, 6.4, 10.0 Hz, 1H), 2.30-
2.40 (m, 2H), 2.51-2.67 (m, 2H), 2.75-2.79 (m, 2H), 3.48 (ddd,
J ) 4.4, 6.4, 6.4 Hz, 1H), 7.07 (dd, J ) 7.6, 7.6 Hz, 1H), 7.28
(dd, J ) 7.6, 7.6 Hz, 2H), 7.50 (d, J ) 7.6 Hz, 2H); 13C NMR
(100 MHz, d8-THF, 25 °C) cis isomer, δ 10.6, 16.5, 24.1, 25.0,
27.4, 32.1, 51.6, 74.0, 122.8, 125.0, 128.2, 129.3, 130.2, 132.2,
141.2, 142.4. HRMS (FAB) calcd for C20H24O2 (a mixture of cis
and trans isomers) (M+) 296.1776, found 296.1782. Anal. Calcd
for C20H24O2: C, 81.04; H, 8.16. Found: C, 80.95; H, 8.27.
1
1639 (CdO), 2087 (CtC), 3242 (tC-H) cm-1; H NMR (400
MHz, CDCl3, 25 °C) δ 2.03 (quint, J ) 7.6 Hz, 2H), 2.74 (tt, J
) 2.0, 7.6 Hz, 2H), 2.87 (tt, J ) 2.0, 7.6 Hz, 2H), 3.03 (s, 1H),
7.43 (dd, J ) 7.6, 7.6 Hz, 2H), 7.54 (dd, J ) 7.6, 7.6 Hz, 1H),
7.83 (d, J ) 7.6 Hz, 2H); 13C NMR (100 MHz, CDCl3, 25 °C) δ
22.5, 35.4, 39.2, 79.0, 86.4, 128.1, 129.3, 129.5, 132.7, 137.3,
148.4, 194.9. Anal. Calcd for C14H12O: C, 85.68; H, 6.16.
Found: C, 85.38; H, 6.04.
1-Eth yn yl-2-p r op ion ylcycloh ex-1-en e (4d ). Substrate 4d
was prepared from 17 (1.3 g, 5.0 mmol, n ) 2) by a similar
procedure for 4b. A colorless oil (0.37 g, 0.24 mmol, 47% yield
for 2 steps); IR (neat) 1662 (CdO), 2088 (CtC), 3256 (tC-H)
cm-1; 1H NMR (400 MHz, CDCl3, 25 °C) δ 1.10 (t, J ) 7.2 Hz,
3H), 1.58-1.72 (m, 4H), 2.26-2.40 (m, 4H), 2.87 (q, J ) 7.2
Hz, 2H), 3.31 (s, 1H); 13C NMR (100 MHz, CDCl3, 25 °C) δ
8.1, 21.6, 21.8, 26.1, 31.7, 34.9, 84.0, 100.5, 122.5, 145.7, 205.3.
HRMS (FAB) calcd for C11H15O (M + H+) 163.1123, found
163.1120.
Typ ica l P r oced u r e for Ch r om iu m -Ca ta lyzed Cyclo-
p r op a n a tion Rea ction s. The complex Cr(CO)6 (5.5 mg, 0.025
mmol) was placed in the flame-dried Schlenk flask and
dissolved in dry and deoxygenated THF (2.0 mL) at room
temperature under N2. This solution was irradiated with a
high-pressure Hg lamp for 2 h at room temperature. Then,
N2 gas was bubbled into the yellow solution for 5 min. To this
yellow solution were added a solution of 4 (0.5 mmol) and an
alkene in THF (2 mL). After the reaction was complete (the
color of the solution changed from blue to yellow), the organic
solvent was removed under reduced pressure and the residue
was subjected to column chromatography on SiO2 with hexane/
AcOEt as an eluent to afford cyclopropanes.
Typ ica l P r oced u r e for Oth er Tr a n sition Meta l-Ca ta -
lyzed Cyclop r op a n a tion Rea ction s of Styr en e w ith 4b.
To a solution of 4 (0.20 mmol) and alkene (0.4-4.0 mmol) in
THF (2 mL) was added a transition metal complex (0.010
mmol) at room temperature under N2. After the reaction was
complete, the reaction mixture was filtered through Florisil.
The organic solvent was removed under reduced pressure and
the residue was subjected to column chromatography on SiO2
with hexane/AcOEt as an eluent to afford the corresponding
cyclopropanes.
Cyclop r op a n e 6c (by [Rh ] Ca ta lyst). A pale yellow oil
(61 mg, 0.20 mmol, 99% yield, cis/trans ) 90/10); IR (neat)
693, 762, 1048, 1153, 1191, 1364, 1440, 1493, 1600, 2931,
1
2974 cm-1; H NMR (300 MHz, d8-THF, 25 °C) cis isomer, δ
1.01-1.09 (m, 1H), 1.08 (s, 9H), 1.26-1.31 (m, 1H), 1.66-1.73
(m, 4H), 1.84 (ddd, J ) 6.3, 6.3, 9.9 Hz, 1H), 2.44-2.64 (m,
2H), 2.73-2.78 (m, 2H), 3.49 (ddd, J ) 4.2, 6.3, 6.3 Hz, 1H),
7.08 (dd, J ) 7.8, 7.8 Hz, 1H), 7.29 (dd, J ) 7.8, 7.8 Hz, 2H),
1
7.51 (d, J ) 7.8 Hz, 2H); H NMR (300 MHz, d8-THF, 25 °C)
trans isomer, δ 1.04-1.11 (m, 1H), 1.19 (ddd, J ) 6.3, 6.3, 6.3
Hz, 1H), 1.26 (s, 9H), 1.68-1.76 (m, 4H), 1.90 (ddd, J ) 3.0,
6.3, 9.6 Hz, 1H), 2.52-2.67 (m, 2H), 2.70-2.76 (m, 2H), 3.48
(ddd, J ) 3.0, 6.3, 6.3 Hz, 1H), 7.10 (dd, J ) 7.8, 7.8 Hz, 1H),
7.30 (dd, J ) 7.8, 7.8 Hz, 2H), 7.49 (d, J ) 7.8 Hz, 2H); 13C
NMR (75 MHz, d8-THF, 25 °C) cis isomer, δ 11.0, 16.7, 22.0,
24.0, 24.1, 24.5, 28.2, 52.3, 74.8, 119.8, 120.1, 124.4, 125.9,
3
129.1, 133.6, 144.9, 146.6; C NMR (75 MHz, d8-THF, 25 °C)
trans isomer, δ 13.9, 18.0, 21.4, 23.9, 23.9, 24.4, 28.5, 53.4,
75.2, 118.7, 120.1, 124.4, 126.2, 129.1, 133.3, 144.8, 147.9.
HRMS (FAB) calcd for C21H26O2 (a mixture of cis and trans
isomers) (M+) 310.1933, found 310.1935. Anal. Calcd for
C
21H26O2 (a mixture of cis and trans isomers): C, 81.25; H,
8.44. Found: C, 80.97; H, 8.52.
Cyclop r op a n e 6d (by [Rh ] Ca ta lyst). A pale yellow oil
(42 mg, 0.16 mmol, 80% yield, cis/trans ) 91/9); IR (neat) 893,
1000, 1039, 1062, 1150, 1192, 1238, 1259, 1364, 1388, 1444,
1593, 2855, 2932, 2973 cm-1; 1H NMR (400 MHz, d8-THF, 25
°C) cis isomer, δ 1.03 (ddd, J ) 5.6, 6.8, 10.0 Hz, 1H), 1.01 (s,
9H), 1.06 (t, J ) 7.6 Hz, 3H), 1.07 (ddd, J ) 4.0, 5.6, 7.2 Hz,
1H), 1.52-1.61 (m, 4H), 1.66 (ddd, J ) 6.0, 7.2, 10.0 Hz, 1H),
2.30-2.51 (m, 4H), 2.41 (q, J ) 7.6 Hz, 2H), 3.33 (ddd, J )
4.0, 6.0, 6.8 Hz, 1H); 13C NMR (75 MHz, d8-THF, 25 °C) cis
isomer, δ 9.4, 12.6, 15.9, 19.6, 20.6, 21.2, 23.8, 23.8, 27.4, 51.0,
73.7, 115.2, 116.5, 143.1, 147.1. HRMS (FAB) calcd for
C
17H27O2 (a mixture of cis and trans isomers) (M + H+)
263.2011, found 263.2006.
Cyclop r op a n e 7a (by [Cr ] Ca ta lyst). A pale yellow oil
(45 mg, 0.16 mmol, 82% yield); IR (neat) 691, 759, 1023, 1056,
1117, 1212, 1285, 1443, 1487, 1548, 1595, 2884, 2929, 2975
Cyclop r op a n e 6a (by [Rh ] Ca ta lyst). A pale yellow oil
(51 mg, 0.20 mmol, 99% yield, cis/trans ) 85/15); IR (neat)
692, 758, 784, 885, 972, 1014, 1025, 1190, 1365, 1390, 1487,
1549, 1595, 2975 cm-1; 1H NMR (300 MHz, d8-THF, 25 °C) cis
isomer, δ 0.95 (ddd, J ) 4.0, 6.4, 6.8 Hz, 1H), 1.09 (s, 9H),
1.13 (ddd, J ) 6.4, 6.8, 9.6 Hz, 1H), 1.95 (ddd, J ) 6.4, 6.4, 9.6
Hz, 1H), 3.51 (ddd, J ) 4.0, 6.4, 6.4 Hz, 1H), 6.04 (d, J ) 3.6
Hz, 1H), 6.62 (d, J ) 3.6 Hz, 1H), 7.15 (dd, J ) 7.6, 7.6 Hz,
1H), 7.30 (dd, J ) 7.6, 7.6 Hz, 2H), 7.60 (d, J ) 7.6 Hz, 2H);
1H NMR (300 MHz, d8-THF, 25 °C) trans isomer, δ 1.07-1.13
(m, 2H), 1.25 (s, 9H), 1.94-1.99 (m, 1H), 3.36 (ddd, J ) 2.8,
2.8, 8.0 Hz, 1H), 6.01 (d, J ) 3.6 Hz, 1H), 6.60 (d, J ) 3.6 Hz,
1
cm-1; H NMR (400 MHz, d8-THF, 25 °C) δ 0.99 (t, J ) 7.2
Hz, 3H), 1.18 (t, J ) 7.2 Hz, 3H), 1.31 (dd, J ) 6.0, 6.8 Hz,
1H), 1.41 (dd, J ) 6.0, 10.4 Hz, 1H), 2.37 (dd, J ) 6.8, 10.4
Hz, 1H), 3.38-3.51 (m, 1H), 3.58-3.75 (m, 3H), 6.09 (d, J )
3.6 Hz, 1H), 6.62 (d, J ) 3.6 Hz, 1H), 7.15 (dd, J ) 7.6, 7.6 Hz,
1H), 7.30 (dd, J ) 7.6, 7.6 Hz, 2H), 7.61 (d, J ) 7.6 Hz, 2H);
13C NMR (100 MHz, d8-THF, 25 °C) δ 15.6, 15.8, 19.2, 24.5,
62.3, 62.8, 92.3, 106.7, 108.1, 123.9, 127.3, 129.2, 132.1, 153.0,
153.4. HRMS (FAB) calcd for C17H20O3 (M+) 272.1412, found
1562 J . Org. Chem., Vol. 69, No. 5, 2004

Catalytic Cyclopropanation of Alkenes
272.1407. Anal. Calcd for C17H20O3: C, 74.97; H, 7.40. Found:
C, 74.90; H, 7.37.
mg, 0.13 mmol, 67% yield); IR (neat) 691, 760, 1034, 1441,
1458, 1493, 1560, 1601, 2932, 2961 cm-1; 1H NMR (400 MHz,
CDCl3, 25 °C) δ 0.80 (dd, J ) 4.4, 8.8 Hz, 1H), 0.84 (t, J ) 7.2
Hz, 3H), 0.98 (t, J ) 7.2 Hz, 3H), 1.02 (dd, J ) 4.4, 5.2 Hz,
1H), 1.13 (qd, J ) 7.2, 14.4 Hz, 1H), 1.27 (qd, J ) 7.2, 14.4
Hz, 1H), 1.35 (qd, J ) 7.2, 14.4 Hz, 1H), 1.50 (qd, J ) 7.2,
14.4 Hz, 1H), 1.64 (dd, J ) 5.2, 8.8 Hz, 1H), 1.67-1.79 (m,
4H), 2.45-2.53 (m, 2H), 2.72-2.79 (m, 2H), 7.14 (dd, J ) 7.6,
7.6 Hz, 1H), 7.34 (dd, J ) 7.6, 7.6 Hz, 2H), 7.55 (d, J ) 7.6 Hz,
2H); 13C NMR (75 MHz, CDCl3, 25 °C) δ 10.7, 10.8, 17.4, 20.8,
21.2, 23.1, 23.2, 23.3, 23.6, 28.8, 29.6, 119.5, 119.8, 123.7, 125.3,
128.3, 132.4, 143.7, 147.3. HRMS (FAB) calcd for C21H26O (M+)
294.1984, found 294.1976. Anal. Calcd for C21H26O: C, 85.67;
H, 8.90. Found: C, 85.42; H, 9.16.
Cyclop r op a n e 7c (by [Cr ] Ca ta lyst). A pale yellow oil
(65 mg, 0.20 mmol, 99% yield); IR (neat) 693, 762, 983, 1054,
1070, 1118, 1201, 1269, 1441, 1493, 1561, 1601, 2929, 2974
1
cm-1; H NMR (400 MHz, d8-THF, 25 °C) δ 0.99 (t, J ) 7.2
Hz, 3H), 1.19 (t, J ) 7.2 Hz, 3H), 1.35 (dd, J ) 5.2, 10.4 Hz,
1H), 1.57 (dd, J ) 5.2, 6.8 Hz, 1H), 1.65-1.78 (m, 4H), 2.26
(dd, J ) 6.8, 10.4 Hz, 1H), 2.50-2.58 (m, 2H), 2.71-2.78 (m,
2H), 3.42-3.50 (m, 1H), 3.57-3.73 (m, 3H), 7.09 (dd, J ) 7.6,
7.6 Hz, 1H), 7.29 (dd, J ) 7.6, 7.6 Hz, 2H), 7.54 (d, J ) 7.6 Hz,
2H); 13C NMR (100 MHz, d8-THF, 25 °C) δ 15.8, 15.8, 17.8,
21.8, 23.7, 24.0, 24.0, 24.5, 62.2, 62.8, 92.3, 120.0, 120.2, 124.4,
126.1, 129.0, 133.3, 144.9, 145.1. HRMS (FAB) calcd for
C
21H26O3 (M+) 326.1882, found 326.1884.
Cyclop r op a n e 13a (by [Rh ] Ca ta lyst). A colorless oil (35
mg, 0.16 mmol, 78% yield, cis/trans ) 43/57); IR (neat) 691,
758, 786, 898, 1019, 1487, 1548, 1595, 1636, 2929, 2956,
Cyclop r op a n e 8c (by [Cr ] Ca ta lyst). A colorless oil (67
mg, 0.17 mmol, 83% yield, as a mixture of cis and trans
isomers); IR (neat) 695, 760, 843, 1203, 1250, 1447, 1494, 1601,
2933 cm-1; 1H NMR (400 MHz, d8-THF, 25 °C) δ -0.18 (s, 9H),
-0.01 (s, 9H), 1.54-1.66 (m, 4H), 1.62 (dd, J ) 6.0, 10.0 Hz,
1H), 1.66-1.80 (m, 4H), 1.74 (dd, J ) 6.4, 10.0 Hz, 1H), 1.96
(dd, J ) 6.4, 7.2 Hz, 1H), 2.00 (dd, J ) 6.0, 7.2 Hz, 1H), 2.16
(dd, J ) 7.2, 10.0 Hz, 1H), 2.38-2.42 (m, 2H), 2.47-2.66
(m, 4H), 2.49 (dd, J ) 7.2, 10.0 Hz, 1H), 2.71-2.75 (m, 2H),
7.02-7.36 (m, 16H), 7.40 (d, J ) 7.6 Hz, 2H), 7.60 (d, J ) 7.6
Hz, 2H); 13C NMR (100 MHz, d8-THF, 25 °C) δ -0.4, -0.4,
17.5, 18.1, 20.0, 20.3, 22.1, 22.3, 22.4, 22.4, 22.8, 23.0, 24.3,
24.6, 61.7, 62.8, 118.0, 118.6, 119.2, 119.9, 122.9, 122.9, 124.4,
124.5, 124.8, 124.8, 125.7, 126.1, 126.6, 127.2, 127.3, 127.4,
131.5, 131.8, 139.4, 139.4, 143.4, 143.4, 143.7, 143.8. HRMS
(FAB) calcd for C26H30O2Si (a mixture of cis and trans isomers)
(M+) 402.2015, found 402.2018. Anal. Calcd for C26H30O2Si (a
mixture of cis and trans isomers): C, 77.57; H, 7.51. Found:
C, 77.28; H, 7.43.
1
3002 cm-1; H NMR (400 MHz, CDCl3, 25 °C) δ 1.10 (s, 3H),
1.15-1.22 (m, 4H), 1.32 (s, 3H), 2.08 (dd, J ) 6.4, 8.8 Hz, 1H),
2.12 (dd, J ) 6.4, 8.8 Hz, 1H), 4.94 (dd, J ) 1.2, 10.4 Hz, 1H),
4.98 (dd, J ) 0.8, 10.8 Hz, 1H), 5.04 (dd, J ) 0.8, 17.2 Hz,
1H), 5.05 (dd, J ) 1.2, 17.6 Hz, 1H), 5.54 (dd, J ) 10.8, 17.2
Hz, 1H), 5.56 (dd, J ) 10.4, 17.6 Hz, 1H), 6.07 (d, J ) 3.2 Hz,
1H), 6.09 (d, J ) 3.2 Hz, 1H), 6.54 (d, J ) 3.2 Hz, 1H), 6.56 (d,
J ) 3.2 Hz, 1H), 7.20 (dd, J ) 7.6, 7.6 Hz, 1H), 7.20 (dd, J )
7.6, 7.6 Hz, 1H), 7.34 (dd, J ) 7.6, 7.6 Hz, 2H), 7.34 (dd, J )
7.6, 7.6 Hz, 2H), 7.61 (d, J ) 7.6 Hz, 2H), 7.62 (d, J ) 7.6 Hz,
2H); 13C NMR (100 MHz, CDCl3, 25 °C) δ 15.8, 19.6, 20.2, 21.8,
24.1, 25.1, 26.1, 26.2, 105.7, 105.7, 108.3, 108.7, 110.6, 112.4,
123.3, 123.3, 126.7, 126.7, 128.5, 128.5, 131.0, 131.0, 140.9,
145.1, 152.2, 152.4, 153.6, 153.9. HRMS (FAB) calcd for
C
16H16O (a mixture of cis and trans isomers) (M+) 224.1201,
found 224.1202. Anal. Calcd for C16H16O (a mixture of cis and
trans isomers): C, 85.68; H, 7.19. Found: C, 85.66; H, 7.36.
Cyclop r op a n e 9c (by [Cr ] Ca ta lyst). A pale yellow solid
(53 mg, 0.18 mmol, 90% yield); mp 87.0-88.8 °C; IR (KBr) 698,
766, 1041, 1105, 1142, 1236, 1245, 1438, 1447, 1599, 2854,
Cyclop r op a n e 13c (by [Cr ] Ca ta lyst). A colorless oil (49
mg, 0.18 mmol, 88% yield, cis/trans ) 50/50); IR (neat) 692,
760, 896, 995, 1030, 1071, 1441, 1493, 1558, 1601, 1633, 2857,
1
2929, 2939, 2953 cm-1; H NMR (400 MHz, d8-THF, 25 °C) δ
1
2930 cm-1; H NMR (400 MHz, CDCl3, 25 °C) δ 1.12 (s, 3H),
0.64-0.76 (m, 1H), 1.07-1.20 (m, 1H), 1.33 (ddd, J ) 6.8, 6.8,
6.8 Hz, 1H), 1.64-1.77 (m, 5H), 1.93 (dddd, J ) 6.8, 6.8, 12.0,
14.0 Hz, 1H), 2.25 (dd, J ) 4.2, 14.0 Hz, 1H), 2.43-2.51 (m,
1H), 2.69-2.78 (m, 3H), 3.16-3.23 (m, 1H), 3.35-3.40 (m, 1H),
3.78 (dd, J ) 6.8, 6.8 Hz, 1H), 7.12 (dd, J ) 7.2, 7.2 Hz, 1H),
7.32 (dd, J ) 7.2, 7.2 Hz, 2H), 7.57 (d, J ) 7.2 Hz, 2H); 13C
NMR (100 MHz, d8-THF, 25 °C) δ 14.9, 17.1, 19.0, 21.8, 23.4,
24.0, 24.0, 24.6, 54.9, 64.8, 119.9, 122.3, 124.5, 126.1, 129.1,
133.5, 145.8, 145.8. HRMS (FAB) calcd for C20H22O2 (M+)
294.1620, found 294.1619.
1.17 (dd, J ) 4.4, 8.8 Hz, 1H), 1.20 (dd, J ) 4.8, 9.2 Hz, 1H),
1.33 (s, 3H), 1.35 (dd, J ) 4.8, 6.4 Hz, 1H), 1.46 (dd, J ) 4.8,
6.4 Hz, 1H), 1.64-1.80 (m, 8H), 1.95 (dd, J ) 6.4, 9.2 Hz, 1H),
2.00 (dd, J ) 6.4, 8.8 Hz, 1H), 2.45-2.55 (m, 4H), 2.70-2.80
(m, 4H), 4.92 (dd, J ) 1.2, 10.8 Hz, 1H), 4.96 (dd, J ) 1.2,
10.8 Hz, 1H), 5.02 (dd, J ) 1.2, 17.6 Hz, 1H), 5.04 (dd, J )
1.2, 17.6 Hz, 1H), 5.58 (dd, J ) 10.8, 17.6 Hz, 1H), 5.58 (dd, J
) 10.8, 17.6 Hz, 1H), 7.13 (dd, J ) 7.6, 7.6 Hz, 1H), 7.15 (dd,
J ) 7.6, 7.6 Hz, 1H), 7.35 (dd, J ) 7.6, 7.6 Hz, 2H), 7.35 (dd,
J ) 7.6, 7.6 Hz, 2H), 7.55 (d, J ) 7.6 Hz, 2H), 7.56 (d, J ) 7.6
Hz, 2H); 13C NMR (100 MHz, CDCl3, 25 °C) δ 16.2, 19.3, 20.2,
20.9, 21.0, 21.7, 23.0, 23.0, 23.1, 23.1, 23.1, 23.5, 23.5, 24.1,
25.7, 25.9, 108.3, 110.1, 111.8, 119.5, 120.3, 120.7, 120.7, 123.8,
123.8, 125.5, 125.5, 128.4, 132.2, 132.2, 141.7, 144.2, 144.3,
145.5, 145.7, 146.1. HRMS (FAB) calcd for C20H22O (a mixture
of cis and trans isomers) (M+) 278.1671, found 278.1668. Anal.
Calcd for C20H22O (a mixture of cis and trans isomers): C,
86.29; H, 7.97. Found: C, 86.38; H, 8.17.
Cyclop r op a n e 10c (by [Rh ] Ca ta lyst). A colorless oil (58
mg, 0.19 mmol, 93% yield, cis/trans ) 8/92); IR (neat) 693,
762, 906, 1029, 1072, 1439, 1494, 1560, 1601, 2855, 2929 cm-1
;
1H NMR (400 MHz, CDCl3, 25 °C) cis isomer, δ 1.45 (ddd, J )
5.2, 8.8, 8.8 Hz, 1H), 1.53-1.70 (m, 4H), 1.61 (ddd, J ) 5.2,
6.4, 6.4 Hz, 1H), 2.19-2.45 (m, 2H), 2.30 (ddd, J ) 6.4, 8.8,
8.8 Hz, 1H), 2.42 (ddd, J ) 6.4, 8.8, 8.8 Hz, 1H), 2.58-2.68
(m, 2H), 7.02-7.16 (m, 6H), 7.24-7.37 (m, 4H); 1H NMR (400
MHz, CDCl3, 25 °C) trans isomer, δ 1.39 (ddd, J ) 4.8, 6.0,
8.8 Hz, 1H), 1.65 (ddd, J ) 4.8, 6.0, 8.8 Hz, 1H), 1.66-1.76
(m, 4H), 2.09 (ddd, J ) 4.8, 6.0, 8.8 Hz, 1H), 2.44 (ddd, J )
4.8, 6.0, 8.8 Hz, 1H), 2.54 (t, J ) 6.0 Hz, 2H), 2.76 (t, J ) 6.0
Hz, 2H), 7.12-7.21 (m, 4H), 7.29 (dd, J ) 7.8, 7.8 Hz, 2H),
7.35 (dd, J ) 7.8, 7.8 Hz, 2H), 7.56 (d, J ) 7.8 Hz, 2H); 13C
NMR (100 MHz, CDCl3, 25 °C) cis isomer, δ 10.7, 16.7, 20.7,
22.8, 22.9, 23.4, 23.6, 119.2, 121.1, 125.4, 125.4, 125.8, 127.6,
128.1, 128.4, 132.3, 138.9, 144.3, 145.2; 13C NMR (100 MHz,
CDCl3, 25 °C) trans isomer, δ 15.8, 20.3, 20.7, 23.0, 23.1, 23.5,
24.8, 118.5, 119.6, 123.8, 125.6, 125.7, 125.8, 128.3, 128.4,
132.1, 142.0, 143.9, 147.3. HRMS (FAB) calcd for C23H22O (a
mixture of cis and trans isomers) (M+) 314.1671, found
314.1671. Anal. Calcd for C23H22O (a mixture of cis and trans
isomers): C, 87.86; H, 7.05. Found: C, 87.99; H, 7.20.
Cyclop r op a n e 14c (by [Rh ] Ca ta lyst). A pale yellow oil
(65 mg, 0.18 mmol, 92% yield, cis/trans ) 90/10); IR (neat)
694, 764, 810, 986, 1071, 1098, 1192, 1271, 1296, 1406, 1440,
1493, 1600, 1725 (CdO), 2858, 2931 cm-1; 1H NMR (400 MHz,
d8-THF, 25 °C) cis isomer, δ 1.03 (ddd, J ) 6.4, 6.4, 9.6 Hz,
1H), 1.33-1.37 (m, 1H), 1.62-1.73 (m, 4H), 1.85 (ddd, J )
6.4, 6.4, 9.6 Hz, 1H), 2.48-2.51 (m, 2H), 2.67-2.70 (m, 2H),
3.47-3.53 (m, 2H), 3.57-3.62 (m, 1H), 3.99-4.03 (m, 2H), 5.59
(d, J ) 10.0 Hz, 1H), 5.88 (dd, J ) 10.0, 16.4 Hz, 1H), 6.16 (d,
J ) 16.4 Hz, 1H), 7.05 (dd, J ) 7.6, 7.6 Hz, 1H), 7.25 (dd, J )
7.6, 7.6 Hz, 2H), 7.50 (d, J ) 7.6 Hz, 2H); 13C NMR (100 MHz,
d8-THF, 25 °C) cis isomer, δ 14.9, 21.0, 23.1, 24.1, 24.3, 24.7,
57.7, 63.1, 68.4, 119.1, 119.8, 123.6, 125.2, 128.1, 128.4, 129.4,
132.4, 144.3, 144.3, 164.9. HRMS (FAB) calcd for C22H24O4 (a
mixture of cis and trans isomers) (M+) 352.1675, found
Cyclop r op a n e 11c (by [Rh ] Ca ta lyst). A colorless oil (39
J . Org. Chem, Vol. 69, No. 5, 2004 1563

Miki et al.
352.1674. Anal. Calcd for C22H24O4 (a mixture of cis and trans
isomers): C, 74.98; H, 6.86. Found: C, 74.60; H, 6.83.
Cyclop r op a n e 15a (by [P t] Ca ta lyst). A colorless oil (11
mg, 0.05 mmol, 26% yield, syn/anti ) 75/25); IR (neat) 691,
758, 786, 1020, 1070, 1385, 1449, 1487, 1548, 1594, 2875, 2953,
Ch r om iu m -Ca t a lyzed Syn t h esis of Bisfu r fu r ylid en e
12. Bisfurfurylidene 12 was obtained by chromium-catalyzed
reaction of 4c (42 mg, 0.20 mmol) without alkenes.
A
yellow solid (37 mg, 0.09 mmol, 87% yield); mp
213.5-216.4 °C; IR (KBr) 692, 761, 944, 1033, 1246, 1352,
1437, 1491, 1596, 2858, 2938 cm-1 1H NMR (400 MHz, d8-
1
3008 cm-1; H NMR (300 MHz, CDCl3, 25 °C) syn isomer, δ
;
1.07 (s, 3H), 1.09 (s, 3H), 1.24-1.31 (m, 2H), 1.94 (t, J ) 8.7
Hz, 1H), 6.11 (d, J ) 3.3 Hz, 1H), 6.56 (d, J ) 3.3 Hz, 1H),
7.20 (dd, J ) 7.5, 7.5 Hz, 1H), 7.35 (dd, J ) 7.5, 7.5 Hz, 2H),
7.62 (d, J ) 7.5 Hz, 2H); 1H NMR (300 MHz, CDCl3, 25
°C) anti isomer, 1.15 (s, 3H), 1.17 (s, 3H), 1.24-1.31 (m, 2H),
1.91-1.97 (m, 1H), 5.95 (d, J ) 3.3 Hz, 1H), 6.51 (d, J ) 3.3
Hz, 1H), 7.15-7.20 (m, 1H), 7.30-7.36 (m, 2H), 7.58 (d, J )
8.1 Hz, 2H); 13C NMR (75 MHz, CDCl3, 25 °C) syn isomer, δ
8.9, 12.2, 15.3, 16.9, 20.0, 105.6, 109.5, 123.3, 126.6, 128.6,
131.2, 152.2, 153.5; 13C NMR (75 MHz, CDCl3, 25 °C) anti
isomer, δ 8.9, 12.2, 15.2, 19.9, 24.9, 104.6, 105.9, 123.1, 126.5,
128.5, 131.2, 151.3, 157.5. HRMS (FAB) calcd for C15H16O (a
mixture of cis and trans isomers) (M+) 212.1201, found
212.1209.
Cyclop r op a n e 16a (by [P t] Ca ta lyst). A colorless oil (10
mg, 0.05 mmol, 23% yield); IR (neat) 691, 758, 783, 1020, 1062,
1383, 1449, 1487, 1548, 1595, 2867, 2953, 3004 cm-1; 1H NMR
(400 MHz, CDCl3, 25 °C) δ 0.90-0.96 (m, 1H), 1.00 (d, J ) 5.6
Hz, 3H), 1.00-1.07 (m, 1H), 1.19 (d, J ) 5.6 Hz, 3H), 1.70 (dd,
J ) 4.8, 8.4 Hz, 1H), 6.03 (d, J ) 3.6 Hz, 1H), 6.55 (d, J ) 3.6
Hz, 1H), 7.19 (dd, J ) 7.6, 7.6 Hz, 1H), 7.34 (dd, J ) 7.6, 7.6
Hz, 2H), 7.61 (d, J ) 7.6 Hz, 2H); 13C NMR (75 MHz, CDCl3,
25 °C) δ 13.3, 18.5, 20.6, 22.3, 22.7, 105.7, 108.0, 123.2, 126.5,
128.5, 131.2, 151.8, 154.9. HRMS (FAB) calcd for C15H16O (a
mixture of cis and trans isomers) (M+) 212.1201, found
212.1207.
THF, 25 °C) δ 1.72-1.80 (m, 8H), 2.59-2.65 (m, 4H), 2.72-
2.78 (m, 4H), 6.75 (s, 2H, vinyl), 7.13 (dd, J ) 7.6, 7.6 Hz, 2H),
7.32 (dd, J ) 7.6, 7.6 Hz, 4H), 7.63 (d, J ) 7.6 Hz, 4H); 13C
NMR (100 MHz, d8-THF, 25 °C) δ 21.0, 22.7, 22.9, 23.4, 111.2,
120.7, 122.8, 124.1, 126.1, 128.3, 131.8, 146.0, 146.8. HRMS
(FAB) calcd for C30H28O2 (trans isomer) (M+) 420.2089, found
420.2080.
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for 21st Century COE program of a United
Approach to New Materials Science from the Ministry
of Education, Culture, Sports, Science, and Technology,
J apan. Financial support by scientific Research (B) (No.
14350468) and Priority Areas (A) “Exploitation of Multi-
Element Cyclic Molecules” from the J apan Society for
the Promotion of Science is gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: The X-ray diffrac-
tion analysis of 9c and 12 and 1H and 13C NMR spectra of
compounds 4d , 6d , 7c, 8c, 9c, 12, 13c, 14c, 15a , and 16a ,
including CIF files. This material is available free of charge
via the Internet at http://pubs.acs.org.
J O0352732
1564 J . Org. Chem., Vol. 69, No. 5, 2004