cis- and enantio-selective cyclopropanation with chiral (ON+)Ru-salen complex as a catalyst

Article abstract of DOI:10.1016/S0040-4020(00)00273-8

Cyclopropanation of styrene with α-diazoacetate in the presence of (R,R)-(salen)ruthenium complex 4 in THF which dissolves the complex exhibits remarkable cis- and enantio-selectivity [cis:trans=97:3, >97% ee (1S,2R)], while the same reaction in hexane which does not dissolve it shows good but opposite sense of enantioselectivity [-83% ee (1R,2S)] together with moderate cis-selectivity (cis:trans=68:32). In homogeneous and heterogeneous conditions, (salen)ruthenium complexes are considered to have different ligand-conformation which, in turn, causes the opposite sense of enantioface selectivity in the cyclopropanation. 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00273-8

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 3501±3509
cis- and Enantio-selective Cyclopropanation with Chiral
(ON1)Ru±Salen Complex as a Catalyst
*
Tatsuya Uchida, Ryo Irie and Tsutomu Katsuki
Department of Molecular Chemistry, Graduate School of Science, Kyushu University 33, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
Received 16 February 2000; accepted 4 April 2000
AbstractÐCyclopropanation of styrene with a-diazoacetate in the presence of (R,R)-(salen)ruthenium complex 4 in THF which dissolves
the complex exhibits remarkable cis- and enantio-selectivity [cis:transˆ97:3, .97% ee (1S,2R)], while the same reaction in hexane which
does not dissolve it shows good but opposite sense of enantioselectivity [283% ee (1R,2S)] together with moderate cis-selectivity
(cis:transˆ68:32). In homogeneous and heterogeneous conditions, (salen)ruthenium complexes are considered to have different ligand-
conformation which, in turn, causes the opposite sense of enantioface selectivity in the cyclopropanation. q 2000 Elsevier Science Ltd. All
rights reserved.
Introduction
that cyclopropanation using Rh2(S-IBAZ)4 complex showed
modest cis-selectivity, though its enantioselectivity is
dependent upon the a-diazoacetate used.8a For example,
cis±trans ratio and enantioselectivity in the cyclopropa-
nation of styrene with ethyl a-diazoacetate are 67:33 and
73% ee (cis-isomer) respectively, while those with bis-
(cyclohexyl)methyl a-diazoacetate are 66:34 and 95% ee
(cis-isomer). Still no satisfactory example of highly cis-
and enantio-selective reaction is known.
Metallosalen complexes are well recognized to serve as
catalysts for transfer reactions of oxene and its equivalents
such as nitrene and carbene.1 Among various metallosalen
complexes (hereafter referred to as M±salen complexes),
optically active second generation Mn(III)±salen complexes
were found to be the most suitable catalysts for asymmetric
oxene transfer reaction such as epoxidation, C±H hydroxyl-
ation, and oxidation of sul®des.2 For these second gener-
ation Mn±salen catalysts, the presence of C3- and C30-
substituents is essential for achieving high enantioselec-
tivity. On the other hand, optically active Co(III)±salen
complexes bearing no substituent at C3 and C30
are the excellent catalysts for carbene transfer reac-
tions such as asymmetric cyclopropanation and S-ylide
formation.2,3
As described above, we found that chiral Co(III)±salen
complex was an excellent catalyst for highly enantio- and
trans-selective cyclopropanation reaction.3b However, in
contrast to Mn±salen complexes in which 20-substituted
naphthyl (or -phenyl) groups at C3 and C30 play a very
important role in enantioselection by the complexes,2 the
Co(III)±salen complexes bearing substituents such as meth-
yl or t-butyl group at C3 and C30 showed no catalysis for
carbene transfer reactions like cyclopropanation and S-ylide
formation.3 These results strongly suggested that ole®ns and
sul®des approach the intermediary Co-carbenoid complex
from the side of C3 and C30. This further suggested that
stereochemistry of metallosalen-catalyzed asymmetric
cyclopropanation would be controlled at need if ole®ns
could approach between suitable chiral C3- and C30-sub-
stituents to the carbenoid species. It was reasonable to
expect that, if the distance between C3 and C30 is appro-
priately expanded, ole®ns could approach the intermediary
carbenoid from C3- and C30 side even if bulky substituents
reside at those carbons.
Asymmetric cyclopropanation of ole®ns, typical carbene
transfer reaction, is the most useful reaction for the synthesis
of optically active cyclopropanes. The reaction of mono-
substituted ole®ns and a-diazoacetates in the presence of
metal complex gives a mixture of cis- and trans-isomers.
Asymmetric version of this reaction started with the
pioneering work by Nozaki et al.4 Following this study,
Aratani et al. for the ®rst time achieved high enantioselec-
tivity together with moderate trans-selectivity in metal-
catalyzed cyclopropanation.5 Subsequent to these studies,
many highly enantioselective cyclopropanation reactions
have been developed,6 but most of them are trans-selective,
except for a few examples.7,8 Recently Doyle et al. reported
Recently we disclosed that chiral (R,S)-(ON1)Ru(II)±salen
complex (1) was an excellent catalyst for asymmetric epoxi-
dation under photo-irradiation.9 The structure of the
complex 1 was unambiguously determined by X-ray
Keywords: cyclopropanation; (salen)ruthenium; metallosalen; photo-
activation.
* Corresponding author. Tel.: 181-92-642-2586; fax: 181-92-642-2607;
e-mail: katsuscc@mbox.nc.kyushu-u.ac.jp
analysis:10 the length (2.04±2.05 A) of the Ru±Oequatorial
Ê
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00273-8

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T. Uchida et al. / Tetrahedron 56 (2000) 3501±3509
Table 1. Asymmetric cyclopropanation of styrene using (ON1)Ru-salen complexes as catalysts (reaction was carried out in styrene at room temperature under
irradiation of incandescent light, unless otherwise mentioned. Enantiomeric excess of the product was determined by HPLC analysis using chiral column
(DAICEL CHIRALCEL OD-H, hexane). Con®guration was determined by the comparison of the elution order with the authentic samples)
Entry
Catalyst
Yield (%)a
cis:trans
cis (% ee)
trans (% ee)
1
2
3
2
3
1
4
4
±
10
45
12
53
6
18:82
11:89
37:63
80:20
44:56
44:56
31
58
12
81
71
0
35
223b
51
51
78
4
5c
6
11
0
1
a Yield was calculated on the amount of a-diazoacetate used by H NMR analysis (see the typical experimental procedure).
b The con®guration of the product is 1S,2S.
c Reaction was carried out in the dark.
Ê
Ê
bond is ca. 0.2 A longer than that (1.85±1.86 A) of the
Co±Oequatorial bond11 and the substituent at C3 largely
inclined toward the apical ligand, leaving a large open
space between the C3- and C30-substituents. Furthermore,
there are several precedents of asymmetric cyclopropa-
nation using chiral ruthenium complexes as catalysts,
though they are highly trans- and enantio-selective.12
Ruthenium ions in these complexes have a site available
for coordination of a-diazoacetate. Although the ruthenium
ion in 1 has no such site, photo-irradiation9 has been con-
sidered to promote the dissociation of one of its apical
ligands,13 endowing the ion with an open apical site. Thus
chiral Ru±salen complex, especially the complex bearing
chiral C3- and C30-substituents, was expected to serve as a
catalyst for stereocontrolled cyclopropanation reaction.
With this expectation, we examined Ru±salen catalyzed
asymmetric cyclopropanation reaction.14
complex (1) as a catalyst, the present reaction was also
remarkably accelerated by photo-irradiation using incan-
descent lamp (National Panasonic LW100v57w) which
illuminates light of wavelength of mostly .400 nm, as a
light source. The reactions in the dark were very slow and
gave poor and unreproducible results (cf. entries 4 and 5).
Under incandescent light, the reaction with complex 2
showed trans-selectivity (entry 1) but enantioselectivity
strongly suffered as compared with the reaction by using
Co(III)-salen complex bearing the same ligand as the cata-
lyst (93% ee, trans-isomer; trans:cisˆ96:4). Next, we
examined the reactions using complexes (1, 3, and 4)
bearing bulky substituents at C3 and C30, as catalysts and
found that these complexes also catalyzed the desired cyclo-
propanation. Complex 3 showed slightly better trans-selec-
tivity but enantioselectivity was modest (entry 2). Reaction
using (R,S)-complex 1 which has bulky 2-phenylnaphthyl
groups as C3- and C30-substituents proceeded with modest
trans- and enantio-selectivity (entry 3). We were, however,
grati®ed by the result obtained with (R,R)-complex 4 which
also has bulky 2-phenylnaphthyl groups at 3- and 30-carbons
but is diastereomeric to (R,S)-complex 1 at the ethylene-
diamine moiety. The reaction catalyzed by 4 showed good
level of cis- and enantio-selectivity (entry 4). Chemical
yield was also acceptable, though there is still a room for
improvement. Despite this, the obtained stereoselectivity
was considered not to be an optimized one from the follow-
ing observation: irradiation caused the decomposition of
a-diazoacetate in the absence of a catalyst and promoted
non-stereoselective cyclopropanation (entry 6). Therefore it
was expected that stereoselectivity would be further
improved if the uncatalyzed decomposition was suppressed
by some means.
Results and Discussion
To suppress this undesired and uncatalyzed reaction, we ®rst
examined the effect of the wavelength of the light on stereo-
selectivity of the present reaction in THF (Table 2). The
reaction irradiated by the light of about 390 nm suffered
slightly lower enantioselectivity probably due to the
photo-catalyzed decomposition of a-diazoacetate. Irradi-
ation of the light of wave length longer than 500 nm
promoted neither the decomposition of a-diazoacetate and
We synthesized three other chiral (ON1)(salen)ruthenium-
(II) complexes 2±4 according to Bosnich's procedure15 and
examined the reaction of styrene and t-butyl a-diazoacetate
in the presence of the complexes (without solvent). The
results obtained are summarized in Table 1. In accord
with other reactions such as epoxidation9 and hetero
Diels±Alder reaction16 using (ON1)(salen)ruthenium(II)

T. Uchida et al. / Tetrahedron 56 (2000) 3501±3509
3503
Table 2. Effect of wavelength of light on stereoselectivity (reaction was carried out in the presence of the catalyst 4 (5 mol %, based on a-diazoacetate used) at
room temperature for 24 h in THF-styrene (10/1 v/v) under irradiation of light of the described wavelength, unless otherwise mentioned)
Entry
Wavelength (nm)
Yield (%)a
cis:transb
cis (% ee)c
trans (% ee)c
d
1
2
3
4
,390
,440
.500
ILf
11
16
3
91:9
97:3
71:29
96:4
91
97
79
99
±
5
259e
9
18
a Yield was calculated on the basis of the amount of a-diazoacetate used. Total yield of cis- and trans-cyclopropanes was determined by 1H NMR analysis
(400 MHz) using 1-bromonaphthalene as an internal standard.
b Ratio of cis- and trans-isomers was determined by 1H NMR analysis (400 MHz).
c Enantiomeric excess of the product was determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OD-H, hexane). Con®guration was
determined by the comparison of the elution order with the authentic samples.
d Not determined.
e Con®guration of the product is 1R,2R.
f ILˆincandescent light
nor the desired cyclopropanation. Finally, the light of ca.
440 nm was found to ef®ciently accelerate the desired disso-
ciation of the apical ligand of (ON1)Ru±salen complex,
without promoting the undesired photo-decomposition of
the a-diazoacetate. Thus, decomposition of the a-diazo-
acetate occurred on the Ru ion and resulted in the excellent
stereoselectivity (entry 2). Fortunately, use of commercial
incandescent lamp was also found to show enantioselec-
tivity as high as the reaction irradiated by the light of ca.
440 nm (entry 4). In addition to this, it was found that the
present reaction in THF was much better in terms of cis- and
enantio-selectivity than the reaction carried out in styrene
without adding extra solvent, though other reaction con-
Based on the analysis of the second generation Mn(III)±
ditions were identical except for the solubility of the
salen complexes, we were able to propose that the salen
ligand of oxo Mn(V)±salen complex was highly pliable
and its conformation was regulated by weak interactions
complex 4 to the reaction mediums used: the complex 4
was completely dissolved in THF, while 4 was partly solved
in styrene (cf. Table 1, entry 4 and Table 2, entry 1). This
suggested that the aggregation state of the complex 4 would
affect the conformation of the salen ligand of the inter-
mediary Ru±carbenoid complex and, in turn, in¯uence the
stereoselectivity of the present reaction.
such as OH±p17 and edge-to-face aromatic interactions.18
We could also determine the structure of (R,S)-
(ON1)Ru(II)±salen complex 1, in which neither the OH±
p (between 200-phenyl group and the apical ligand) nor the
edge-to-face aromatic interaction (between C3- and C30-
substituents) exists and the ®ve-membered chelate ring
including ruthenium ion and ethylenediamine unit takes a
twisted envelope conformation.10 These results suggested
that the ligand of complex 1 would be conformationally
more ¯exible than the corresponding Mn±salen complex.
The ligand of (R,R)-(ON1)Ru(II)±salen complex 4 is also
expected to be conformationally ¯exible because neither the
OH±p nor the edge-to-face aromatic interaction also exists
in the complex 4 and it is reasonable to consider that the
®ve-membered chelate ring of the complex 4 also takes a
twisted envelope conformation. These considerations
suggested us that the ligand conformation of (ON1)Ru(II)±
salen complexes might be dependent on their association
state which should be strongly related to the solvent used:
the dissolved (homogeneous) and precipitated (hetero-
geneous) complexes might have different conformations,
as discussed above. Thus, the effect of solvent on stereo-
selectivity was next examined by using incandescent lamp

3504
T. Uchida et al. / Tetrahedron 56 (2000) 3501±3509
Table 3. Solvent effect on enantioselectivity in cyclopropanation of styrene using 4 as a catalyst (reaction was carried out in the presence of t-butyl a-
diazoacetate (0.1 mmol), styrene (0.3 mmol) and solvent [0.35 ml (solvent/styreneˆ10/1 v/v)] at room temperature under irradiation of incandescent light,
unless otherwise mentioned. Enantiomeric excess of the product was determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OD-H,
hexane). Con®guration was determined by the comparison of the elution order with the authentic samples)
Entry
Solvent (ml)
THF
DME
AcOEt
CH2Cl2
CH3CN
Yield (%)a
cis:trans
cis (% ee)
trans (% ee)
1
2
3
4
5
18
19
17
21
0
96: 4
96: 4
92: 8
84:16
±
99
98
96
92
29b
10
51
79
±
±
6
7
8
9
10
Pyridine
Diethyl ether
Hexane
Heptane
Diisopropyl ether
0
±
±
±
10
10
14
5
63:37
68:32
74:26
67:33
215c
283c
271c
281c
64
50
72
48
1
a Yield was calculated on the amount of a-diazoacetate used by H NMR analysis (see the experimental section).
b The con®guration of the product is 1S,2S.
c The con®guration of the product is 1R,2S.
as a light source with three different kinds of solvents: (i)
solvents of high dissolving power such as THF, dimethoxy-
ethane (DME), ethyl acetate, and dichloromethane; (ii)
solvents of high dissolving power and high coordinating
ability such as acetonitrile and pyridine; and (iii) solvents
of poor dissolving power such as hexane, heptane, and diiso-
propyl ether (Table 3). Catalyst 4 was dissolved in the ®rst
class of solvents and the reactions in these solvents all
showed high enantio- and cis-selectivity to give the
(1S,2R)-isomer preferentially, though ethereal solvents
gave slightly better results (entries 1±4). On the other
hand, no reaction was observed in the second class of
solvents, despite that 4 was dissolved in these solvents
(entries 5 and 6). These results agreed with the proposed
mechanism for metal-catalyzed diazo decomposition, in
which diazo compound is coordinated to the metal ion and
generates a metal±carbene complex.19 Coordinating solvent
should interrupt the coordination of a-diazoacetate to the
ruthenium ion and the desired cyclopropanation did not
occur in this kind of solvents. Complex 4 was insoluble to
the third class of solvents and the reactions in these solvents
were carried out under heterogeneous conditions, showing
moderate cis- and good enantio-selectivity (entries 8±10).
However, the sense of enantioselection in the formation of
the major cis-isomer is opposite to that observed in the
reactions in the ®rst class of solvents (cf. entries 1±4 and
8±10). The reaction with the supernatant liquid of the
hexane-suspension of complex 4 did not proceed at all
even under the photo-irradiated conditions. Although the
reaction mechanism is unclear at present, the obtained
results indicated that the reversal of enantioselection has
no relation to the functionality of solvents or to their polarity
Table 4. Asymmetric cyclopropanation of various ole®ns (reaction was carried out in the presence of the catalyst 4 (5 mol %, based on a-diazoacetate used) at
room temperature in a mixture of THF and substrate under irradiation of incandescent light)
Entry
Substrate
Styrene
Styrene
THF-substrate (v/v)
Time (h)
Yield (%)a
cis:transb
cis (%ee, con®gn)
trans (%ee, con®gn)
1
2
3
4
5
6
7
8
9
2:1
1:1
1:2
2:1
2:1
1:1
10:1
2:1
1:1
48
48
48
48
48
48
24
48
48
36
45
43
44
62
80
38
74
77
93:7
93:7
76:24
93:7
94:6
98c (1S,2R)d
97c (1S,2R)d
88c (1S,2R)d
95c,f
2c (1R,2R)d
15c (1R,2R)d
41c (1R,2R)d
Styrene
e
p-Chlorostyrene
p-Methoxystyrene
p-Methoxystyrene
a-Methylstyrene
a-Methylstyrene
a-Methylstyrene
±
96c,f
5c,f
94:6
97c,f
17c,f
23f,h
53f,h
83:17
81:19
80:20
97f,g
97f,g
96f,g
±
e
a Yield was calculated on the basis of the amount of a-diazoacetate used. Total yield of cis- and trans-cyclopropanes was determined by 1H NMR analysis
(400 MHz) using 1-bromonaphthalene as an internal standard.
b Ratio of cis- and trans- isomers was determined by 1H NMR analysis (400 MHz).
c Enantiomeric excess of the product was determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OD-H, hexane).
d Con®guration was determined by the comparison of the elution order with the authentic samples.
f Absolute con®guration has not been determined.
e Enantiomeric excess has not been determined.
g Enantiomeric excess of the product was determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OJ, hexane).
h Enantiomeric excess of the product was determined by HPLC analysis using chiral column [DAICEL CHIRALCEL OD-H (x2), hexane].

T. Uchida et al. / Tetrahedron 56 (2000) 3501±3509
3505
Table 5. Asymmetric cyclopropanation using ethyl a-diazoacetate as the carbene source (reaction was carried out in the presence of the catalyst 4 (5 mol %,
based on a-diazoacetate used) at room temperature in a mixture of THF and substrate under irradiation of incandescent light)
Entry
Substrate
THF-substrate (v/v)
Time (h)
Yield (%)a
cis:transb
cis(% ee, con®gn)
trans (% ee, con®gn)
1
2
3
4
5
6
7
Styrene
2:1
2:1
1:1
2:1
1:1
2:1
1:1
48
48
48
48
48
48
48
33
53
53
51
56
61
57
93:7
84:16
79:21
94:6
92:8
73:27
72:28
88c(1S,2R)d
88e,f
35c(1R,2R)d
50f,g
p-Chlorostyrene
p-Chlorostyrene
p-Methoxystyrene
p-Methoxystyrene
a-Methylstyrene
a-Methylstyrene
86c,f
62e,f
93c,f
24c,f
92c,f
32c,f
90c,f
±
±
e
91c,f
e
a Yield was calculated on the basis of the amount of a-diazoacetate used. Total yield of cis- and trans-cyclopropanes was determined by 1H NMR analysis
(400 MHz) using 1-bromonaphthalene as an internal standard.
1
b Ratio of cis- and trans- isomers was determined by H NMR analysis (400 MHz).
c Enantiomeric excess of the product was determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OB-H, hexane).
d Con®guration was determined by the measurement of speci®c rotation.21
e Enantiomeric excess of the product was determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OJ, hexane).
f Absolute con®guration has not been determined.
g Enantiomeric excess has not been determined.
(cf. entries 1±4 and 8±10). The following explanation
seems to be the most rational at this moment. Complex 4
is dissolved completely in the ®rst class of solvents and
behaves as a monomeric catalyst which decomposes
a-diazoacetate upon irradiation, while 4 is not dissolved
in the third class of solvents and the activation (dissociation
of apical ligand) should occur on the surface of the insoluble
solid 4. Therefore, the reversal of enantioselection is attri-
buted to that these homo- and hetero-geneous catalysts have
different ligand-conformation which is correlated with the
sense of asymmetric induction.14b In connection with this
problem, the substandard selectivity observed in the cyclo-
propanation of styrene without solvent (Table 1, entry 4)
which had been attributed to the intervention of non-
catalyzed reaction,14a should be explained as follow: the
solubility of complex 4 to styrene is not very high and the
reaction was performed under partly suspended conditions.
Therefore, both homo- and hetero-geneous processes that
show opposite sense of enantioselection to each other
competed and diminished the stereoselectivity of the reac-
tion to substandard level. In accord with these phenomena,
the reaction in diethyl ether which has dissolving power
inbetween THF and diisopropyl ether showed the mediate
enantioselectivity [215% ee (1R,2S)] between the stereo-
chemistry of the reactions in these two ethereal solvents
(entry 7).
because the present reaction is bimolecular reaction. As
expected, the chemical yield of the cyclopropanecarboxyl-
ate was improved to some extent as the ratio of THF and
styrene was reduced to 1:1 (v/v) without causing severe
decay of stereoselectivity (Table 4, entries 1 and 2) but
further reduction of THF decreased the stereoselectivity of
the reaction to a considerable extent, as the reaction became
suspended (entry 3). We also examined the cyclopropa-
nation of other ole®ns with high substrate-concentration
and could achieve excellent enantioselectivity (.95% ee)
as well as high cis-selectivity (entries 4±8). Again, reduc-
tion of THF content improved the chemical yields of the
desired products (entries 5±6 and 7±9).
Up to here, t-butyl a-diazoacetate was used as a carbenoid
source. However, it is well known that enantioselectivity of
the metal-catalyzed cyclopropanation is dependent on the
steric bulkiness of the ester alkyl group of the a-diazo-
acetate used and the selectivity generally improves as the
bulkiness of the ester alkyl group increases. Ethyl a-diazo-
acetate has a small ethyl group as the ester alkyl group, but it
is more readily available than t-butyl a-diazoacetate. Thus,
we examined the cyclopropanation using ethyl a-diazo-
acetate as a carbene source (Table 5). Reactions also
showed high cis- and good enantio-selectivity, though
stereoselectivity is diminished to some extent.20
As described in Table 2, the reaction irradiated by a suitable
light in THF showed excellent cis- and enantioface-selec-
tivity but the chemical yields of cyclopropanecarboxylates
were unsatisfactory (entries 2 and 4). These low yields were
attributed to slow reaction between the intermediary Ru±
carbenoid and styrene, since the formation of a considerable
amount of the mixture of fumaric and maleic acid esters was
observed during the reactions. For example, the yield of a
mixture of maleic and fumaric acid esters was 32%, when
the reaction was performed in THF-styrene (10/1). We
expected that the formation of fumaric and maleic acid
esters would be suppressed by slowly adding a-diazoacetate
to the reaction medium and the yield of cyclopropane-
carboxylate would be improved. However, the slow addition
of t-butyl a-diazoacetate did not improve the chemical
yield. Then, we tried to reduce the amount of THF in the
reaction medium to enhance the substrate concentration,
Complex 4 was puri®ed by silica gel column chroma-
tography and used for the present reaction. However, during
the chromatographic puri®cation, the formation of a new
Ru±salen complex 5 was observed. The FABMS analysis
of the new complex indicated that the apical chloro ligand of
4 was replaced with hydroxo ligand [measurement of
FABMS (m-nitrobenzyl alcohol): m/z 973(M1),
956(M12OH)]. We were interested in the catalysis of
complex 5. Thus, we examined the reaction of styrene and
t-butyl a-diazoacetate in the presence of 5 (Table 6). It is
noteworthy that the reaction proceeded even in the dark and
showed high cis- (89:11) and enantio-selectivity [92% ee,
cis-isomer (1S,2R)]. On the other hand, the reaction under
incandescent light showed a similar level of cis- and enantio-
selectivity to that observed with the complex 4 under incan-
descent light (cf., Table 1, entry 4 and Table 6, entry 2). This
might suggest that the ligand dissociated upon irradiation is

3506
T. Uchida et al. / Tetrahedron 56 (2000) 3501±3509
Table 6. Asymmetric cyclopropanation of styrene using (ON1)Ru-salen complex 5 as the catalyst (reaction was carried out in styrene using 5 (5 mol %) at
room temperature for 1 day. For the determination of enantiomeric excess of the product and the con®guration of the products, see the footnote of Table 1)
Entry
Substrate
Styrene
Styrene
Yield (%)
cis:trans
cis (% ee, con®gn)
trans (% ee, con®gn)
1a
2c
3a
62b
45b
32d
89:11
78:22
77:23
92 (1S,2R)
81 (1S,2R)
72e
37 (1R,2R)
54 (1R,2R)
34e
p-Chlorostyrene
a The reaction was carried out in the dark.
b Isolated yield.
c The reaction was carried out under incandescent light.
d Yield was calculated by 1H NMR analysis.
e Absolute con®guration has not been determined.
Scheme 1.
not nitrosyl but chloro ligand.9,13 However, further study
is necessary to draw a conclusion on this issue. We also
examined the cyclopropanation of p-chlorostyrene using 5
as the catalyst in the dark (entry 3). Although the reaction
was cis-selective,10 its cis- and enantio-selectivity decreased
to a considerable extent.
In conclusion, we were able to achieve high cis- and enantio-
selective cyclopropanation with (R,R)-(ON1)Ru±salen
complex 4 for the ®rst time. Although the mechanism of
stereoselection of this reaction by the (ON1)Ru±salen
complex is still unclear, its ligand conformation was
suggested to affect enantioselection by examining the
solvent effect on enantioselectivity. The possible approach-
ing path of ole®ns was also proposed on the basis of the
stereochemistry of the reactions with various (ON1)Ru±
salen complexes as catalysts.
Although the mechanism of asymmetric induction is unclear
at present, we have assumed that ole®ns approach the carbe-
noid-carbon passing by the C3 (30)-substituents as hypothe-
sized. This assumption was supported from the following
experiments. The complex 6 bearing the chirality only at
the binaphthyl unit also showed good cis-selectivity
(cis:transˆ79:21) as well as good enantioselectivity [91%
ee, cis-isomer (1R,2R); 0% ee, trans-isomer], though the
chemical yield was poor. On the other hand, the modi®-
cation of 3,30-substituents of complex 4 by replacing
200-phenyl group with methyl group decayed stereoselec-
tivity: the reaction with complex 7 showed the moderate
trans-selectivity and poor enantioselectivity (Scheme 1).
Experimental
1H NMR spectra were recorded at 400 MHz on a BRUKER
DPX-400 or a JEOL GX-400 instrument. All signals were
expressed as ppm down ®eld from tetramethylsilane used as
an internal standard (d-value in CDCl3). IR spectra were
obtained with a SHIMADZU FTIR-8600 instrument. Optical
rotations were measured with a JASCO P-1020 polarimeter.
Column chromatography was conducted on silica gel BW-
820MH, 70±200 mesh ASTM, available from FUJI
SILYSIA CHEMICAL LTD. Preparative thin layer chroma-
tography was performed on 0.5 mm£20 cm£20 cm E.
Merck silica gel plate (60 F-254). Enantiomeric excesses
were determined by HPLC analysis using SHIMADZU
LC-10AT-VP equipped with an appropriate optically active
column, as described in the footnotes of the corresponding
Tables. Solvents were dried and distilled shortly before use.
Ole®ns and t-butyl a-diazoacetate were also distilled before
In general, cyclopropanations of styrene with a-diazo-
acetate in the presence of chiral Cu, Co, and Rh complexes
give a mixture of trans- and cis-isomers, the con®gurations
at C1 of which are the same.6 In contrast to this, the present
reaction under homogeneous conditions provided the trans-
and cis-products isomeric at C1 (e.g., Table 3, entries 2±4),
except for the reaction in THF (THF/styreneˆ10/1; Table 3,
entry 1). The reason for this unusual selectivity is unclear at
present.

T. Uchida et al. / Tetrahedron 56 (2000) 3501±3509
3507
use. Use of non-freshly distilled ole®ns and t-butyl
(NO1)Ru(II)±salen complex 4
a-diazoacetate may decay stereoselectivity of the reaction.
Reactions were carried out under an atmosphere of nitrogen
if necessary.
(NO1)Ru(II)±salen complex 4 was prepared in the same
procedure as described for the synthesis of 1, except for
the puri®cation. The reaction mixture was concentrated
under vacuum and the residue was quickly chromato-
graphed on silica gel (CH2Cl2/acetoneˆ50/1) to give
(NO1)Ru(II)±salen complex 4 as red±brown crystals
(NO1)Ru(II)±salen complex 1
1
To a solution of (1S,2S)-1,2-diaminocyclohexane (0.17 g,
1.5 mmol) in EtOH (20 ml) was added (aR)-3-formyl-2-
hydroxy-20-phenyl-1,10-binaphthyl (1.1 g, 3.0 mmol) and
the mixture was stirred for 6 h at room temperature. The
resulting light yellow precipitate was separated from the
solution by ®ltration, and dried under vacuum. This pre-
cipitate was dissolved in N,N-dimethylformamide (DMF).
NaH (60% dispersion in mineral oil, 0.13 g, 3.3 mmol) was
weighed into a ¯ask and washed with dry hexane
(3£1.0 ml). To the ¯ask were added the above yellow
solution with stirring (hydrogen evolved and the mixture
turned to a clear red solution). After 1 h, Ru(NO)Cl3´H2O
(0.42 g, 1.6 mmol) was added to the suspension and the
mixture was stirred at 1108C for 48 h. The resulting opaque
red-brown mixture was concentrated under high vacuum.
The residue was dissolved in CH2Cl2 and washed with
water. The CH2Cl2 layer was dried over MgSO4 and evapo-
rated to dryness. The residue was recrystallized from
CH2Cl2/CH3CN to give Ru(II)-salen complex 1 as red-
(60%). H NMR (400 MHz): d 8.25 (d, Jˆ2.0 Hz, 1H),
8.22 (d, Jˆ1.5 Hz, 1H), 8.16 (d, Jˆ8.0 Hz, 1H), 8.03 (d,
Jˆ8.5 Hz, 1H), 7.99 (d, Jˆ8.5, 1H) 7.87±7.82 (m, 3H), 7.67
(d, Jˆ8.0 Hz, 1H), 7.63±7.58 (m, 3H), 7.45±7.34 (m, 3H),
7.29±6.95 (m, 9H), 6.59±6.55 (m 2H), 6.30 (pseudo-d,
Jˆ7.5 Hz, 2H), 6.20±6.10 (m, 6H), 3.99 (br t, Jˆ10.4 Hz,
1H), 3.03 (br t, Jˆ10.4 Hz, 1H), 2.677 (br d, Jˆ12.0 Hz,
1H), 2.60 (br d, Jˆ11.0 Hz, 1H), 2.05±1.98 (br m, 2H),
1.71±1.63 (br m, 1H), 1.53±1.33 (br m, 3H). IR (KBr):
3051, 2937, 2860, 1824, 1707, 1639, 1614, 1577, 1546,
1490, 1446, 1423, 1384, 1346, 1319, 1296, 1274, 1246,
1226, 1190, 1169, 1145, 1124, 1091, 1072, 1028, 951,
864, 818, 793, 775, 760, 696, 667, 640, 582, 548, 499,
470, 428 cm21. Anal. Calcd for C60H44ClN3O3´H2O: C,
71.38; H, 4.59; N, 4.16%. Found: C, 71.24; H, 4.59; N,
4.13%. HRFABMS m/z. Calcd for C60H44O3N3ClRu(M1):
991.2128. Found: 991.2114.
(NO1)Ru(II)±salen complex 5
1
brown crystals (0.63 g, 42%). H NMR (400 MHz): d 8.34
(d, Jˆ1.0 Hz, 1H), 8.27 (d, Jˆ1.5 Hz, 1H), 8.09 (d, Jˆ
8.0 Hz, 1H), 7.99 (d, Jˆ8.0 Hz, 1H), 7.95 (d, Jˆ8.0 Hz,
1H), 7.82 (s, 1H), 7.78 (d, Jˆ8.0 Hz, 1H), 7,74 (s, 1H),
7.63 (d, Jˆ8.0 Hz, 1H), 7.53 (d, Jˆ8.0 Hz, 1H), 7.46±
7.40 (m, 2H), 7.31±7.22 (m, 5H), 7.17±6.96 (m, 6H), 6.91
(d, Jˆ8.5 Hz, 1H), 6.70 (pseudo-q, Jˆ7.0 Hz, 2H), 6.45±
6.36 (m, 6H), 6.18 (pseudo-d, Jˆ7.0 Hz, 2H), 4.04 (br t,
Jˆ10.5 Hz, 1H), 3.14 (br t, Jˆ10.5 Hz, 1H), 2.77 (br d,
Jˆ10.5 Hz, 1H), 2.67 (br d, Jˆ10.0 Hz, 1H), 2.07±2.00
(br m, 2H), 1.74±1.66 (br m, 1H), 1.58±1.36 (br m, 3H).
IR (KBr): 3051, 2933, 2858, 1844, 1641, 1614, 1578, 1491,
1446, 1423, 1391, 1321, 1225, 1192, 1147, 1028, 955, 868,
818, 756, 700, 581, 544, 428 cm21. Anal. Calcd for
C60H44ClN3O3Ru´1/2H2O: C, 72.03; H, 4.53; N, 4.20%.
Found: C, 72.16; H, 4.73; N, 4.25%. HRFABMS m/z.
Calcd for C60H44O3N3ClRu(M1): 991.2128. Found:
991.2104.
(NO1)Ru±salen complex 4 (115.2 mg, 0.12 mmol) was
dissolved in CHCl3. To the solution was added silica gel
(3 g) and the mixture were stirred for 1 day. The suspension
was ®ltered and the ®ltrate was concentrated in vacuo.
The residue was chromatographed on silica gel (CH2Cl2/
acetone/MeOHˆ50/1/1) to give (NO1)Ru±salen complex
1
5 as red crystals (53.6 mg, 47%). H NMR (400 MHz): d
8.20±8.18 (m, 4H), 7.99 (d, Jˆ7.5 Hz, 1H), 7.97 (d, Jˆ
6.5 Hz, 1H), 7.86 (s, 1H), 7.83 (s, 1H), 7.69 (d, Jˆ8.0 Hz,
1H), 7.67 (d, Jˆ8.5 Hz, 1H), 7.55 (d, Jˆ7.5 Hz, 1H), 7.53
(d, Jˆ8.0 Hz, 1H), 7.46±7.40 (m, 2H), 7.30±7.15 (m, 6H),
7.11±7.00 (m, 4H), 6.64 (t, Jˆ7.0 Hz, 1H), 6.55 (t,
Jˆ7.0 Hz, 1H), 6.15±6.08 (m, 8H), 3.79 (br t, Jˆ10.5 Hz,
1H), 3.06 (br t, Jˆ10.5 Hz, 1H), 2.65 (br d, Jˆ14.0 Hz, 1H),
2.55 (br d, Jˆ10.5 Hz, 1H), 2.06±2.01 (br m, 2H), 1.85±
1.75 (br m, 1H), 1.62±1.50 (br m, 1H), 1.38±1.33 (br m,
2H). IR (KBr): 3545, 3051, 2931, 2860, 1815, 1699, 1643,
1614, 1579, 1549, 1491, 1446, 1423, 1387, 1348, 1321,
1296, 1246, 1229, 1190, 1170, 1145, 1124, 1091, 1030,
951, 864, 820, 794, 762, 746, 696, 611, 582, 546, 499,
(NO1)Ru(II)±salen complex 2
467,
430 cm21
.
HRFABMS
m/z.
Calcd
for
(NO1)Ru(II)±salen complex 2 was prepared in the same
procedure as described for the synthesis of 1, except for
the puri®cation. The residue was quickly chromatographed
on silica gel (CHCl3/acetoneˆ100/1) to give the Ru(II)±
C60H45O4N3(M1): 973.2471. Found: 973.2463.
(NO1)Ru(II)±salen complex 6
1
salen complex 2 as red-brown crystals (15%). H NMR
(NO1)Ru(II)±salen complex 6 was prepared in the same
procedure as described for the synthesis of 1, except for
the puri®cation. The resulting opaque red±brown mixture
was concentrated under high vacuum. The residue was
dissolved in CH2Cl2, washed with water and dried under
vacuum to give complex 6 as orange crystals (53%). IR
(KBr): 3053, 1838, 1645, 1614, 1578, 1551, 1495, 1425,
1389, 1312, 1227, 1190, 1148, 1124, 1082, 1049, 953,
820, 746, 702, 665, 578, 517, 430 cm21. HRFABMS m/z.
(400 MHz): d 7.77 (d, Jˆ1.5 Hz, 1H), 7.72 (d, Jˆ1.5 Hz,
1H), 7.42±7.22 (m, 10H), 7.14±7.06 (m, 4H), 6.38 (d,
Jˆ7.3 Hz, 1H), 6.37 (d, Jˆ7.3 Hz, 1H), 5.67 (dd, Jˆ1.5
and 11.2 Hz, 1H), 4.93 (dd, Jˆ1.5 and 11.2 Hz, 1H), 3.68
(s, 3H), 3.67 (s, 3H). IR (KBr): 3059, 3030, 3001, 2936,
2833, 1834, 1622, 1531, 1464, 1418, 1364, 1294, 1258,
1221, 1159, 1040, 1009, 970, 918, 826, 800, 760, 704,
667, 621, 552, 517, 469 cm21. HRFABMS m/z. Calcd for
C30H26O3N5ClRu(M1): 645.0610. Found: 645.0593.

3508
T. Uchida et al. / Tetrahedron 56 (2000) 3501±3509
Calcd for C56H38O3N3ClRu(M1): 937.1658. Found
937.1646.
Jˆ5.1, 5.7 and 7.3 Hz, 1H), 1.25 (ddd, Jˆ5.1, 7.8 and
8.6 Hz, 1H), 1.18 (s, 9H). IR (neat): 3005, 2978, 2932,
1726, 1599, 1495, 1454, 1391, 1367, 1292, 1254, 1213,
1169, 1147, 1093, 1034, 1014, 970, 899, 833, 777, 756,
710, 617 cm21. Anal. Calcd for C14H17ClO2: C, 66.53; H,
6.78% Found: C, 66.82; H, 6.97%.
(NO1)Ru(II)±salen complex 7
(NO1)Ru(II)±salen complex 7 was prepared in the same
procedure as described for the synthesis of 1, except for
the puri®cation. The reaction mixture was concentrated
under vacuum and the residue was quickly chromato-
graphed on silica gel (CH2Cl2/acetoneˆ50/1) followed by
recrystallization from CH2Cl2 and acetone to give complex
7 as red±brown crystals (10%). 1H NMR (400 MHz): d 8.58
(s, 1H), 8.44 (s, 1H), 8.02±7.89 (m, 5H), 7.75 (d, Jˆ8.5 Hz,
1H), 7.70±7.65 (m, 2H) 7.39 (t, Jˆ7.5 Hz, 1H), 7.30 (t,
Jˆ7.2 Hz, 1H), 7.23 (d, Jˆ9.0 Hz, 1H), 7.18±7.13 (m,
2H), 7.09±6.99 (m, 6H), 6.94 (d, Jˆ8.5 Hz, 1H), 6.68±
6.62 (m, 2H), 4.22 (br t, Jˆ10.8 Hz, 1H), 3.36 (br t,
Jˆ10.5 Hz, 1H), 2.92 (br d, Jˆ13.0 Hz, 1H), 2.78 (br d,
Jˆ12.0 Hz, 1H), 2.18±2.13 (br m, 2H), 1.97±1.88 (br m,
1H), 1.77±1.67 (br m, 1H), 1.77 (s, 3H), 1.55±1.43 (br m,
2H), 1.48 (s, 3H). IR (KBr): 3051, 2941, 2860, 1840, 1643,
1614, 1577, 1550, 1508, 1485, 1446, 1421, 1386, 1342,
1319, 1226, 1190, 1147, 1124, 1068, 1028, 954, 873, 812,
779, 746, 688, 650, 572, 499, 430 cm21. Anal. Calcd for
C50H40ClN3O3Ru´H2O: C, 67.83; H, 4.78; N, 4.75%.
Found: C, 67.53; H, 4.78; N, 4.89%.
tert-Butyl cis-2-(4-methoxyphenyl)cyclopropane-1-
carboxylate
Colorless oil. Yield 62% (96% ee); [a]2D6ˆ23.28 (c 0.85,
1
CHCl3). H NMR (400 MHz): d 7.18 (d, Jˆ8.5 Hz, 2H),
6.80 (d, Jˆ8.5 Hz, 2H), 3.77 (s, 3H), 2.46 (ddd, Jˆ7.0,
8.5 and 9.0 Hz, 1H), 1.93 (ddd, Jˆ5.5, 7.5 and 9.0 Hz,
1H), 1.57 (ddd, Jˆ5.0, 5.5 and 7.0 Hz, 1H), 1.21 (ddd,
Jˆ5.0, 7.5 and 8.5 Hz, 1H), 1.17 (s, 9H). IR (neat): 3003
2976, 2932, 2837, 1724, 1612, 1582, 1516, 1460, 1460,
1391, 1367, 1292, 1250, 1211, 1173, 1148, 1113, 1082,
1036, 970, 899, 833, 800, 779, 745 cm21. Anal. Calcd for
C15H20O3: C, 72.55; H, 8.12%. Found: C, 72.83; H, 8.34%.
tert-Butyl cis-2-methyl-2-phenylcyclopropane-1-
carboxylate
Colorless oil. Yield 77% (96% ee); [a]2D4ˆ242.18 (c 0.43,
1
CHCl3). H NMR (400 MHz): d 7.19±7.16 (m, 5H), 1.80
(dd, Jˆ7.6 and 5.5 Hz, 1H), 1.70 (dd, Jˆ5.5 and 4.5 Hz,
1H), 1.45 (s, 3H), 1.13 (s, 9H), 1.07 (dd, Jˆ7.6 and 4.5 Hz,
1H). IR (KBr): 3061, 3007, 2974, 2930, 2868, 1722, 1605,
1499, 1446, 1389, 1370, 1337, 1290, 1248, 1150, 1090, 978,
847, 781, 754, 700, 552, 476 cm21. Anal. Calcd for
C15H20O2: C, 77.55; H, 8.68%. Found: C, 77.67; H, 8.68%.
General procedure for asymmetric cyclopropanation
using (NO1)Ru(II)±salen complex 4 as a catalyst
To a THF solution (0.24 ml) of (NO1)Ru(II)±salen complex
4 (4.9 mg, 5 mmol) was added styrene (0.12 ml) under N2.
To the mixture, was added tert-butyl a-diazoacetate (14 ml,
0.1 mmol), stirred for 48 h under incandescent light (100 V,
57 W), and then concentrated in vacuo. The residue was
passed through a short silica gel column (hexane/
i-Pr2Oˆ1/0 to 4/1) to give a 7:93 mixture of tert-butyl
trans- and cis-2-phenylcyclopropane-1-carboxylates. Their
enantiomeric excesses and con®guration were determined
as described in the footnote d of Table 4. Further puri®-
cation by preparative TLC (silica gel, hexane/i-Pr2Oˆ4/1)
gave tert-butyl cis-2-phenylcyclopropane-1-carboxylates as
a single isomer.
Ethyl cis-2-phenylcyclopropane-1-carboxylate
Colorless oil. Yield 30% (88% ee); [a]2D4ˆ122.88 (c0.25,
CHCl3). 1H NMR (400 MHz): d 7.26±7.19 (m, 5H), 3.87 (q,
Jˆ7.3 Hz, 2H), 2.58 (ddd, Jˆ7.4, 8.7 and 9.3 Hz, 1H), 2.07
(ddd, Jˆ5.7, 7.8 and 9.3), 1.71 (ddd, Jˆ5.1, 5.7 and 7.4 Hz,
1H), 1.32 (ddd, Jˆ5.1, 7.8 and 8.7 Hz, 1H), 0.97 (t,
Jˆ7.3 Hz, 3H). IR (neat): 3059, 3026, 2982, 2933, 1728,
1605, 1499, 1454, 1381, 1275, 1182, 1161, 1086, 1034, 961,
862, 827, 795, 752, 721, 694, 476 cm21. Anal. Calcd for
C12H14O2: C, 75.76; H, 7.42%. Found: C, 75.62; H, 7.57%.
tert-Butyl cis-2-phenylcyclopropane-1-carboxylate
Ethyl cis-2-(4-chlorophenyl)cyclopropane-1-carboxylate
Colorless oil. Yield 42% (86% ee); [a]2D4ˆ26.58 (c 0.74
Colorless oil. Yield 36% (98% ee); [a]2D4ˆ118.08 (c 0.73,
1
CHCl3). H NMR (400 MHz): d 7.29±7.16 (m, 5H), 2.53
1
CHCl3). H NMR (400 MHz): d 7.24±7.18 (m, 4H), 3.90
(ddd, Jˆ7.5, 8.5 and 9.5 Hz, 1H), 1.98 (ddd, Jˆ5.5, 7.5 and
9.5 Hz, 1H), 1.64 (ddd, Jˆ5.0, 5.5 and 7.5 Hz, 1H), 1.24
(ddd, Jˆ5.0, 7.5 and 8.5 Hz, 1H), 1.13 (s, 9H). IR (neat):
3059, 2976, 2930, 1722, 1603, 1456, 1389, 1366, 1290,
1254, 1211, 1169, 1148, 1082, 1032, 968, 901, 853, 795,
746, 721, 696 cm21. Anal. Calcd for C14H18O2: C, 77.03; H,
8.31%. Found: C, 77.00; H, 8.37%.
(q, Jˆ7.3, 2H), 2.51 (ddd, Jˆ7.5, 8.6 and 9.2 Hz, 1H), 2.08
(ddd, Jˆ5.6, 7.8 and 9.2 Hz, 1H), 1.67 (ddd, Jˆ5.1, 5.6, and
7.5 Hz, 1H), 1.33 (ddd, Jˆ5.1, 7.8 and 8.6) 1.02 (t,
Jˆ7.3 Hz, 3H). IR (neat): 2983, 1726, 1495, 1387, 1277,
1184, 1161, 1094, 1034. 1020, 962, 903, 833, 762,
706 cm21. Anal. Calcd for C12H13ClO2: C, 64.15; H,
5.83%. Found: C, 64.06; H, 5.94%.
tert-Butyl cis-2-(4-chlorophenyl)cyclopropane-1-
carboxylate
Ethyl cis-2-(4-methoxyphenyl)cyclopropane-1-
carboxylate
Colorless oil. Yield 18% (97% ee); [a]2D6ˆ24.98 (c 0.76,
1
CHCl3). H NMR (400 MHz): d 7.23 and 7.20 (pseudo-
Colorless oil. Yield 48% (91% ee); [a]2D4ˆ26.68 (c 0.27,
CHCl3). 1H NMR (400 MHz): d 7.18 (pseudo-d, Jˆ8.6 Hz,
2H), 6.80 (pseudo-d, Jˆ8.6 Hz, 2H), 3.90 (q, Jˆ7.3 Hz,
ABq, Jˆ8.5 Hz, 4H), 2.47 (ddd, Jˆ7.3, 8.6 and 9.3 Hz,
1H), 1.99 (ddd, Jˆ5.7, 7.8 and 9.3 Hz, 1H), 1.59 (ddd,

T. Uchida et al. / Tetrahedron 56 (2000) 3501±3509
3509
T. Organometallics 1992, 11, 645±652. (b) It has been reported
that cyclopropanation using a cyclopentadienyl iron complex as
the catalyst shows high cis-selectivity, though in a non-enantio-
selective manner: Seitz, W. J.; Saha, A. K.; Hossain, M. M.
Organometallics 1993, 12, 2604±2608.
2H), 3.77 (s, 3H), 2.52 (ddd, Jˆ7.5, 8.7 and 9.2 Hz, 1H),
2.03 (ddd, Jˆ5.6, 7.8 and 9.2 Hz, 1H), 1.66 (ddd, Jˆ5.0, 5.6
and 7.5 Hz, 1H), 1.30 (ddd, Jˆ5.0, 7.8 and 8.7 Hz, 1H), 1.02
(t, Jˆ7.3 Hz, 3H). IR (neat): 2984, 2837, 1726, 1612, 1581,
1516, 1462, 1381, 1296, 1250, 1182, 1090, 1034, 960, 899,
833, 773, 675, 471, 411 cm21. Anal. Calcd for C13H16O3: C,
70.89; H, 7.32%. Found: C, 70.72; H, 7.33%.
8. (a) Doyle, M. P.; Zhou, Q.-L.; Simonsen, S. H.; Lynch, V.
Synlett 1996, 697±698. (b) Ishitani, H.; Achiwa, K. Synlett 1997,
781±782.
Ethyl cis-2-methyl-2-phenylcyclopropane-1-carboxylate
Colorless oil. Yield 44% (91% ee); [a]2D4ˆ247.68 (c 0.48,
9. Takeda, T.; Irie, R.; Shinoda, Y.; Katsuki, T. Synlett 1999,
1157±1159.
10. Takeda, T.; Irie, R.; Katsuki, T. Synlett 1999, 1166±1168.
11. The lengths of Co-equatorial oxygen atom bonds in (salen)±
1
CHCl3). H NMR (400 MHz): d 7.29±7.17 (m, 5H), 3.85
and 3.81 (ABqq, Jˆ10.9 and 7.1 Hz, 2H), 1.90 (dd, Jˆ7.8
and 5.6 Hz, 1H), 1.78 (dd, Jˆ5.6 and 4.9 Hz, 1H), 1.46 (s,
3H), 1.15 (dd, Jˆ7.8 and 4.9 Hz, 1H), 0.94 (t, Jˆ7.1 Hz,
3H). IR (KBr): 3028, 2964, 2930, 2870, 1728, 1605, 1499,
1447, 1381, 1271, 1238, 1167, 1024, 970, 905, 845, 768,
698, 478 cm21. Anal. Calcd for C13H16O2: C, 76.44; H,
7.90%. Found: C, 76.21; H, 7.92%.
Ê
cobalt(III) complexes are in the range of 1.85±1.86 A: Read, J. M.;
Jacobsen, E. N. J. Am. Chem. Soc. 1999 121 6086±6087.
12. (a) Nishiyama, H.; Itoh, Y.; Matsumoto, H.; Park, S.-B.; Itoh,
K. J. Am. Chem. Soc. 1994, 116, 2223±2224. (b) Nishiyama, H.;
Itoh, Y.; Sugawara, Y.; Matsumoto, H.; Aoki, K.; Itoh, K. Bull.
Chem. Soc. Jpn. 1995, 68, 1247±1262. (c) Frauenkron, M.;
Berkessel, A. Tetrahedron Lett. 1997, 38, 7175±7176. (d) Lo,
W.-C.; Che, C.-M.; Cheng, K.-F.; Mak, T. C. W. Chem. Commun.
1997, 1205±1206. (e) Gross, Z.; Galili, N.; Simkhovich, L.
Tetrahedron Lett. 1999, 40, 1571±1574.
Acknowledgements
13. Lorkovic, I. M.; Miranda, K. M.; Lee, B.; Bernhard, S.;
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Financial supports from a Grant-in-Aid for Scienti®c
Research from the Ministry of Education, Science, Sports,
and Culture, Japan, and Asahi glass foundation are grate-
fully acknowledged.
14. A part of this study has been communicated: (a) Uchida, T.;
Irie, R.; Katsuki, T. Synlett 1999, 1163±1165. (b) Uchida, T.; Irie,
R.; Katsuki, T. Synlett 1999, 1793±1795.
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