Highly Enantioselective Cyclopropanation with Co(II)-Salen Complexes: Control of cis- and trans-Selectivity by Rational Ligand-Design

Article abstract of DOI:10.1002/1615-4169(20010129)343:1<79::aid-adsc79>3.0.co;2-8

Cyclopropanation of styrene derivatives with alkyl α-diazoacetate in the presence of the second-generation (salen)cobalt(II) complex 6 proceeded with excellent cis- and enantioselectivity. On the other hand, the cyclopropanation in the presence of complex 14 which was designed on the basis of the mechanism of asymmetric induction by complex 6 showed good trans- and excellent enantio-selectivity.

Full text of DOI:10.1002/1615-4169(20010129)343:1<79::aid-adsc79>3.0.co;2-8

FULL PAPERS
Highly Enantioselective Cyclopropanation
with Co(II)-Salen Complexes: Control of cis-
and trans-Selectivity by Rational Ligand-Design
Tatsuo Niimi, Tatsuya Uchida, Ryo Irie, Tsutomu Katsuki*
Department of Chemistry, Faculty of Science, Graduate School, Kyushu University 33, Hakozaki,
Higashi-ku, Fukuoka 812±8581, Japan
Fax: +81-92-6 42±26 07; e-mail: katsuscc@mbox.nc.kyushu-u.ac.jp
Received June 26, 2000; Accepted September 20, 2000
Keywords: (salen)co-
balt(II)
asymmetric cyclopro-
panation;
pane; cis-selectivity;
trans-selectivity
complex;
Abstract: Cyclopropanation of styrene derivatives of the mechanism of asym-
with alkyl a-diazoacetate in the presence of the sec- metric induction by com-
ond-generation (salen)cobalt(II) complex 6 pro- plex 6 showed good trans-
ceeded with excellent cis- and enantioselectivity. and excellent enantio-
On the other hand, the cyclopropanation in the pres- selectivity.
cyclopro-
ence of complex 14 which was designed on the basis
[
11]
MEPY and its derivatives , dirhodium(II) tetra-
Introduction
[
12]
kis[3(S)-phthalimido-2-piperidinonate],
and (sal-
[
13]
Highly strained three-membered ring compounds en)cobalt(III) complexes
have been developed for
such as oxirane, aziridine, and cyclopropane are im- asymmetric cyclopropanation. However, most of
portant building blocks for organic synthesis and them are trans-selective while cis-selective reactions
[
14]
much effort has been directed towards exploitation are limited to only a few examples:
of methodologies for their asymmetric synthesis.
Doyle et al.
have recently reported that cyclopropanation using
Although various methodologies are available today, the Rh (S-IBAZ) complex shows modest cis-selectiv-
the cycloaddition of oxenoids, as well as their isoelec- ity, though its enantioselectivity is dependent upon
[
1]
2
4
[
14b±e]
tronic species, nitrenoids and carbenoids, to p-bonds the a-diazoacetate used.
For example, the cis-
is the practically most important one to construct this trans ratio and the enantioselectivity in the cyclopro-
class of compounds. For these reactions, differentia- panation of styrene with ethyl a-diazoacetate are
tion of the enantiotopic faces of the double bonds is 69 : 31 and 76% ee (cis-isomer), respectively, while
the main stereochemical issue. However, another those with bis(cyclohexyl)methyl a-diazoacetate are
stereochemical issue, cis-trans selectivity, is imposed 66 : 34 and 95% ee (cis-isomer). No satisfactory exam-
on the cyclopropanation reaction due to the presence ple of a highly cis- and enantioselective reaction is as
of a substituent at the carbenoid carbon. Thus, simul- yet known.
taneous control of these two stereochemical issues is
indispensable for achieving highly efficient cyclopro- complexes (hereafter referred to as M-salen com-
panation.
plexes) are excellent catalysts for asymmetric trans-
The first metal-catalyzed asymmetric cyclopropa- fer reactions of oxenoids and their isoelectronic spe-
We have recently disclosed that chiral metallosalen
[
15]
nation using a chiral copper complex as the catalyst cies.
In connection with this study, we examined
[
2]
was reported in 1965 by Nozaki, Noyori et al. and asymmetric cyclopropanation using Co-salen com-
this pioneering work was developed by Aratani et plexes as catalysts. A chiral Co(II)-salen complex
[
3]
al. into a practical, highly enantioselective process was originally used as the catalyst for asymmetric cy-
[
16]
by modifying the chiral Schiff base ligand. Subse- clopropanation but the stereoselectivity was low.
quent to these studies, many excellent metal-cata- Later, we found that chiral Co(III)-salen complexes
[
4]
[5]
lyzed methodologies using copper-semicolines,
catalyzed cyclopropanation reactions with high
[
6]
[7]
copper-bis(oxazolines), copper-bipyridines, cop- trans-selectivity and moderate enantioselectivity to-
per-bis(azaferrocenes) of face-chirality,
nium-PYBOX, ruthenium-porphyrins,
[
8]
[13a]
ruthe- gether with good chemical yield.
rhodium- high enantioselectivity was realized by using a modi-
Furthermore,
[9]
[10]
Adv. Synth. Catal. 2001, 343, No. 1
Ó WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2001
1615-4150/01/34301-79±88 $ 17.50-.50/0
79

asc.wiley-vch.de
[
19]
fied Co(III)-salen complex 1 bearing electron-donat- gand substituent or the apical ligand.
Further-
ing methoxy groups at C5 and C5' and an apical bro- more, Co(III)-salen complexes catalyze high-yielding
[
13b]
[13]
mo ligand (Scheme 1).
On the other hand, Co(III)- cyclopropanation reactions (vide supra).
Thus, we
salen complexes bearing substituents like a methyl or expected that a suitably substituted Co(II)-salen com-
t-butyl group at C3 and C3' showed no catalytic activ- plex might serve as a catalyst for asymmetric and
ity. This suggested that olefins approached the inter- high-yielding cyclopropanation, even if the complex
mediate Co(V)-carbenoid species from its C3 and C3' carries 3- and 3'-substituents. Accordingly, we exam-
side and that such an approach was strongly disfa- ined Co(II)-salen catalyzed asymmetric cyclopropa-
[
20]
vored by the presence of 3- and 3'-substituents. How- nation reactions.
ever, it has been well recognized that, in many metal-
losalen-catalyzed reactions, 3- and 3'-substituents
play important roles in determination of the stereo- Results and Discussion
[15]
chemistry.
These observations prompted us to use
a chiral Ru-salen complex as the catalyst for asym- To explore this possibility, we prepared five chiral
metric cyclopropanation for the following reasons: i) Co(II)-salen complexes (3±7) and examined the re-
Ê
the Ru±Oequat bond in an Ru-salen complex is ca. 0.2 A actions of styrene 8 and t-butyl ꢀ-diazoacetate with
longer than the Co±Oequat bond in Co(III)-salen com- them as the catalysts (Table 1). Complex 3 which
plexes, and ii) the longer Ru±O bond increases the has the same ligand as 1 showed moderate trans-
distance between the C3- and C3'-carbons in the Ru- and enantioselectivity but it is noteworthy that the
salen complex and thus makes the approach of the enantiomeric excess of the minor cis-isomer was
olefin from the C3 and C3' side possible even if substi- good (86% ee). Furthermore, the direction of enan-
tuents are present at C3 and C3'. As expected, Ru- tioselection by 3 was the opposite of that by 1. This
salen complexes bearing substituents at C3 and C3' suggested that the conformation of the salen ligands
showed catalytic activity for cyclopropanation and of 3 and 1 or olefin's approaching paths to those cat-
high cis- as well as high enantioselectivity was alysts differ from each other. To our delight, com-
achieved for the first time in the cyclopropanation plexes 4 and 5 bearing substituents at C3 and C3'
+
with the (R,R)±(ON )Ru(II)-salen complex 2 as the were found to serve as catalysts for cyclopropanation
[17]
catalyst.
However, the chemical yield was less than and their stereochemistry was again moderately
satisfactory due to the undesired reaction of the inter- trans- and enantioselective (entries 2 and 3). The
mediate Ru-carbenoid with a-diazoacetate to give fu- stereoselection realized by 4 and 5 were identical to
maric and maleic acid esters. The ligand of Ru-salen that by 1 and the enantiomeric excesses of minor cis-
complex was expected to be highly pliable from X-ray isomers were also good. Since the presence or ab-
[
18]
structure analysis.
On the other hand, although the sence of C3- and C3'- groups did not affect the direc-
Co(II)±Oequat bond in a Co(II)-salen complex is tion of enantioselection, it was considered that the
roughly equal to that in a Co(III)-salen complex, the olefins approached the carbenoid species derived
Co(II)-salen complexes have been reported to adopt from Co(II)-salen complexes from the ethylenedi-
various ligand conformations, depending on the li- amine side. Although the formation of fumaric and
maleic acid esters was detected in reactions using 4
and 5, we were encouraged by these results and next
examined the reaction with the (R,R)-Co(II)-salen
complex 6 that has the same ligand as complex 2. In
contrast to the reactions with complexes 4 and 5, the
reaction with complex 6 proceeded smoothly with
excellent cis- and enantioselectivity and only a trace
amount of fumaric and maleic acid esters (< 1%) was
detected (entry 4). It is noteworthy that the direction
of enantioface selection of 8 by complex 6 was oppo-
site to that by complex 2 bearing the same ligand as
6, although the reaction conditions were the same
except that the reaction with 2 was carried out under
photo-irradiated conditions. This again suggested
that substrates approach the carbenoid species de-
rived from complexes 2 and 6 from different direc-
tions (vide infra). On the other hand, Yamada et al.
recently reported that the rate and the enantioselec-
tivity of the cyclopropanation using a chiral aldimi-
nato-cobalt(II) complex as the catalyst, the ligand of
Scheme 1.
8
0
Adv. Synth. Catal. 2001, 343, 79±88

FULL PAPERS
Table 1. Asymmetric cyclopropanation of styrene 8 using Co(II)-salen complexes as catalysts
[a]
[b]
[c]
[c]
entry
catalyst
yield
cis
:
trans
cis
trans
(
%)
(% ee)
(% ee)
1
2
3
4
5
6
7
8
9
3
4
5
6
6
6
6
6
7
9
39
23
88
89
74
5
19
17
33
92
98
98
94
98
97
:
:
:
:
:
:
:
:
:
81
83
67
8
2
2
6
2
3
86
84
74
96
98
97
93
98[
58
64
20
72
[
[
[
[
d]
[e]
±
±
±
±
d][f]
g]
[e]
[e]
h]
[e]
90
18
i]
[e]
±99
±
[
a]
1
Total yield of trans- and cis-cyclopropanes. Calculated on the basis of the amount of a-diazoacetate used, by H NMR ana-
lysis (400 MHz) using 1-bromonaphthalene as an internal standard.
[
[
b]
c]
1
Determined by H NMR analysis (400 MHz).
Determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OD-H, hexane). Configuration was determined
by comparison of the elution order with the authentic samples.
[
[
[
d]
e]
f]
NMI (10 lmol, 10 mol%) was added.
Not determined.
Reaction was carried out with the recovered complex: After completion of the first reaction, the mixture was concentrated
in vacuo and washed with hexane to remove organic components. The resulting residue was used for the second reaction.
[
[
[
g]
h]
i]
Reaction was carried out with 1 mol% of catalyst in the presence of NMI (2 lmol, 2 mol%).
Reaction in THF (0.1 mL) was carried out with 1 mol% of catalyst in the presence of NMI (10 lmol, 10 mol%).
Absolute configuration was 1S,2R.
which is structurally similar to salen ligand, were
Table 2. Asymmetric cyclopropanation of various olefins
using complex 6 as the catalyst at room temperature; reac-
tion time = 24 h
improved by adding N-methylimidazole (NMI) to
[
21]
the reaction medium.
Based on this report, we
also performed the present reaction in the presence
of NMI and found that both cis- and enantioselectiv-
ity were further improved upto 98 : 2 and 98% ee (en-
try 5). It is noteworthy that 6 was reusable without
any loss of cis- and enantioselectivity (entry 6). The
turnover frequency of the catalyst in this reaction
was estimated to be ca. 4.4 (mol product/mol cata-
lyst/h) over the first hour. When catalyst-loading
was reduced to 1 mol%, the reaction became slow
and the stereoselectivity was slightly diminished (en-
try 7). However, it was found that, even if catalyst-
loading was reduced to 1 mol%, the reaction pro-
ceeded smoothly with high stereoselectivity when it
was carried out at a high substrate concentration in
the presence of an excess amount of NMI (entry 8).
Another advantage of 6 is its high stability: it is stor-
able at least for 3 months at room temperature under
dry air.
[
a]
[b]
[c]
[d]
entry olefin THF
ml)
yield
(%)
cis:trans
cis
(% ee)
trans
[e]
[e]
(
(% ee)
[
f]
[g]
1
2
3
4
10
11
12
9
1.2
0.5
1.2
0.5
85
84
94
39
97 : 3
97 : 3
98 : 2
83 : 17
96[
±
±
±
f]
[g]
96
97
99
[
h]
[g]
[i]
[j]
99
[a]
9
= a-methylstyrene, 10 = p-chlorostyrene, 11 = p-meth-
oxystyrene, 12 = 2-vinylnaphthalene.
Olefins (0.5 mmol), t-butyl a-diazoacetate (0.1 mmol),
catalyst 6 (5 mol%, based on a-diazoacetate used), and NMI
[b]
(
10 lmol).
[
c]
Total yield of trans- and cis-cyclopropanes. Calculated on
1
the basis of the amount of a-diazoacetate used, by H NMR
analysis (400 MHz) using 1-bromonaphthalene as an inter-
nal standard.
Determined by H NMR analysis (400 MHz).
Absolute configuration has not been determined.
[
[
[
d]
e]
f]
1
Determined by HPLC analysis using chiral column (DAI-
CEL CHIRALCEL OD-H, hexane).
We also examined the reaction using the (R,S)-
Co(II)-salen complex 7 in the presence of NMI. The
reaction also exhibited excellent cis- and enantio-
selectivity, but the reaction was slow (entry 9). The
diastereomeric complexes 6 and 7 differ in the chiral-
ity of their ethylenediamine units and show the oppo-
site senses of enantioselectivity.
[g]
Not determined.
Determined by HPLC analysis using chiral column (DAI-
CEL CHIRALCEL OD-H, hexane/i-PrOH = 200/1).
Determined by HPLC analysis using chiral column (DAI-
CEL CHIRALCEL OJ, hexane).
Determined by HPLC analysis using chiral column [DAI-
CEL CHIRALCEL OD-H (´ 2), hexane].
[h]
[i]
[j]
Adv. Synth. Catal. 2001, 343, 79±88
81

asc.wiley-vch.de
Table 3. Asymmetric cyclopropanation with ethyl ꢀ-diazo-
acetate as the carbene source in the presence of 6 at room
temperature; reaction time = 24 h
Under the optimized conditions, we examined the
cyclopropanation of other substrates (Table 2). All
the reactions examined also showed excellent cis-
and enantioselectivity, except that the reaction of ꢀ-
methylstyrene 9 showed a diminished cis-selectivity
of 83%. Only trace amounts of fumaric and maleic
acid esters were detected in all the reactions and the
chemical yields of the desired cyclopropanes were
good, except for the reaction of 9 which was much
slower than other reactions. Although the absolute
configurations of the products have not been deter-
mined, HPLC analyses revealed that the configura-
tions of the major cis-isomers of these reactions were
also opposite to the configurations of the correspond-
ing cis-isomers obtained with complex 2 (vide supra).
It is, however, noteworthy that the catalysts 2 and 6
showed the same sense of enantioface selection only
in the cyclopropanation of 9. The reason for this unu-
sual behavior of 9 is unclear at present.
[a]
[b]
entry olefin
THF/olefin yield
v/v) (%)
cis :
trans
cis
trans
[c]
(
(% ee) (% ee)
[
d][e]
[f]
[f]
[f]
1
2
3
4
8
10
11
9
10/6
10/6
10/7
10/7
quant
quant
quant
quant
99 : 1
97 : 3
95 : 5
96[
±
±
±
g]
96[
g]
93
94
[g]
[g]
85 : 15
94
[
a]
Olefins (0.5 mmol), ethyl a-diazoacetate (0.1 mmol), cata-
lyst 6 (5 mol%, based on a-diazoacetate used), and NMI
10 mol%, based on ethyl a-diazoacetate used).
(
[
b]
Total yield of trans- and cis-cyclopropanes. Calculated on
1
the basis of the amount of a-diazoacetate used, by H NMR
analysis (400 MHz) using 1-bromonaphthalene as an inter-
nal standard.
[
[
[
c]
d]
e]
1
Determined by H NMR analysis (400 MHz).
Absolute configuration of the product was 1S,2R.
Determined by HPLC analysis using chiral column (DAI-
CEL CHIRALCEL OB-H, hexane).
[
[
f]
Not determined.
Determined by HPLC analysis using chiral column (DAI-
In general, the stereoselectivity of asymmetric cy-
clopropanation decreases as the steric requirement
of the ester alkyl group of the a-diazoacetate becomes
smaller. However, ethyl a-diazoacetate is more
g]
CEL CHIRALCEL OD-H, hexane).
Table 4. Asymmetric cyclopropanation of styrene 8 using Co(II)-salen complexes as catalysts at room temperature; reaction
time = 24 h
[a]
[b]
entry
catalyst
Yield
cis
:
trans
cis
trans
(%)
(% ee)
(% ee)
[
c]
1
2
3
4
5
6
13
14
15
16
5
48
19
29
25
89
61
98
25
18
97
54
51
:
:
:
:
:
:
2
75
82
3
46
49
92
91
78[
±
98
86
d]
[c]
±2
±
81
61
39
44
17
[
a]
1
Total yield of trans- and cis-cyclopropanes. Calculated on the basis of the amount of a-diazoacetate used, by H NMR ana-
lysis (400 MHz) using 1-bromonaphthalene as an internal standard.
[
[
[
b]
c]
d]
1
Determined by H NMR analysis (400 MHz).
Not determined.
Absolute configuration is 1S,2R.
8
2
Adv. Synth. Catal. 2001, 343, 79±88

FULL PAPERS
Figure 1. Proposed model for the conformation of Co(IV)-carbenoid species and substrate-approach.
readily available than t-butyl a-diazoacetate and we
examined the cyclopropanation with ethyl a-diazo-
acetate (Table 3). Again, high cis- and enantioselec-
tivities were observed, though slightly diminished as
compared with the reactions with t-butyl a-diazoace-
tate. However, all the reactions examined proceeded
smoothly to give the desired cyclopropanes in quanti-
tative yields.
To study the mechanism of asymmetric induction
in the present reaction, we synthesized several other
Co(II)-salen complexes (13±17) according to the fol-
lowing hypotheses (Table 4). From the X-ray struc-
[
19d,f,g]
tures of Co(II)-salen complexes,
we assumed
that the five-membered chelate rings including co-
balt ion and ethylenediamine unit in the Co(IV)-car-
benoid species (R,R)-18 derived from 6 would adopt
a half-chair conformation and their salen ligands
would take a moderately folded stepped-conforma- that exchange of the cyclohexanediamine unit with a
[22,23]
tion (Figure 1).
We also assumed that a carbe- diphenylethylenediamine unit did not have much af-
noid ester group would protrude towards the N(b) fect on the stereoselectivity of the reaction whereas
atom because this carbenoid-ester conformation al- the reaction rate was retarded (cf. Table 1, entry 5
lows the olefin's approach along the Co±N(a) bond and Table 4, entry 1). The same phenomena were ob-
beyond a downward equatorial substituent [see Fig- served in the reactions with complexes 5 and 17 (en-
ure 1, (R,R)-18]. This is the sterically most favored ap- tries 5 and 6).
proach and the approach from the opposite face of the
carbenoid is intercepted by the C3-substituent.
A carbenoid derived from complex 16 should adopt
two equilibrium conformations, (R,S)-20 and (R,R)-
[
24]
The results described above supported this assump- 20, but the equilibrium was considered to lean to-
tion (vide supra). In connection with this considera- wards (R,S)-20 because of the steric repulsion be-
tion, the slow reaction with the (R,S)-complex 7 as tween the carbenoid ester group and the 2''-phenyl
the catalyst was attributed to the following reason: group which is located very close to the carbenoid
2
''-phenyl group is located near to the approaching group. However, because (R,S)-20 has a structure
path. Furthermore, since substrates approach along similar to (R,S)-19, the catalytic activity of (R,S)-20
the Co±N bond, the presence of bulky substituents at was considered to be inferior to that of (R,R)-20. Since
the diamine part was considered to retard the reac- these two factors cancel each other out, complex 16
tion. This consideration was supported by the fact was not expected to show good enantioselectivity.
Adv. Synth. Catal. 2001, 343, 79±88
83

asc.wiley-vch.de
Table 5. Asymmetric cyclopropanation using complex 14 as the catalyst at room temperature; reaction time = 24 h
[a]
[b]
[c]
entry
olefin
THF/olefin
v/v)
R
yield
(%)
cis : trans
cis
(% ee)
trans
(% ee)
(
[
d]
[d]
1
2
3
4
5
6
7
8
9
8
10/6
10/6
10/6
10/6
10/6
10/7
10/7
10/7
10/7
t-butyl
ethyl
ethyl
t-butyl
ethyl
t -butyl
ethyl
91
27 : 73
31 : 69
99 : 1
15 : 85
22 : 78
25 : 75
33 : 67
58 : 42
57 : 43
93[
98
95
±
99
96
95
94
99
e]
[e]
º
º
quant
quant
88
quant
51
quant
quant
quant
79
[f]
[e]
[g]
96[
d]
d]
d]
d]
d]
d]
[h]
10
87[
73[
82
[i]
º
[d]
11
º
9
[
[d]
82[
[j]
t-butyl
ethyl
93[
93
[d]
º
97
[
a]
Olefins (0.5 mmol), t-butyl or ethyl a-diazoacetate (0.1 mmol), catalyst 6 (5 mol%, based on a-diazoacetate used), and NMI
10 mol%, based on ethyl a-diazoacetate used).
Total yield of trans- and cis-cyclopropanes. Calculated on the basis of the amount of a-diazoacetate used, by H NMR ana-
(
[
b]
1
lysis (400 MHz) using 1-bromonaphthalene as an internal standard.
[
[
[
[
[
[
c]
d]
e]
f]
1
Determined by H NMR analysis (400 MHz).
Determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OD-H, hexane).
Determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OB-H, hexane).
This reaction was catalyzed by catalyst 6.
g]
h]
Not determined.
Determined by HPLC analysis using optically active column (DAICEL CHIRALCEL OD, hexane:i-PrOH=100 : 1), after the
ester was converted into the acetate by the sequence: i) LiAlH4 reduction and ii) acetylation.
[
[
i]
j]
Determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OJ, hexane).
Determined by HPLC analysis using chiral column (DAICEL CHIRALCEL OD-H (´ 2), hexane).
Nevertheless, the two conformers (R,S)-20 and (R,R)- excellent enantioselectivity (> 94% ee). The use of t-
0 were expected to show high cis-selectivity on ac- butyl a-diazoacetate (R = t-butyl) resulted in a slightly
count of their conformational similarity with (R,R)- better selectivity than that of ethyl a-diazoacetate (R=
8 and (R,S)-19, respectively. These expectations ethyl) (Table 5).
2
1
agreed with the results obtained with complex 16 (Ta-
ble 4, entry 4). These results and the above hypothesis
on enantioface selection by the carbenoid species
Conclusion
(
R,R)-18 derived from 6 suggest that the presence of
the 2''-phenyl group strengthens cis-selectivity by
pushing the ester alkyl group towards the incoming
olefin. Therefore, we were intrigued by the catalytic
activity of the complexes 14 and 15 which carry a
methyl group and a hydrogen atom at C2'' in place of
the phenyl group, respectively (entries 2 and 3). The
introduction of these small groups at the 2''-position
should allow the ester alkyl group directing away
from the incoming olefin and, in turn, induce trans-
cis selectivity in cyclopropanation. In fact, both com-
plexes 14 and 15 did show moderate trans-selectivity.
Among them, complex 14 showed excellent enantio-
selectivity while complex 15 exhibited only moderate
selectivity. This was attributed to the fact that the C3-
naphthyl substituent lacking its 2''-substituent could
not completely intercept the olefin's approach from
the C3-side. Although the yields of cyclopropanes
were less than satisfactory, they were improved by re-
ducing the amount of THF without any decay of the
stereoselectivity (Table 5, entry 1). With these results
in hand, we examined the cyclopropanation of other
olefins with complex 14 as the catalyst. The reactions
of other olefins also showed moderate trans-selectiv-
ity, except for the reaction of a-methylstyrene 9, and
In conclusion, we have demonstrated that the reason-
able ligand-design of a Co(II)-salen complex based on
its asymmetry-inducing mechanism enables both cis-
and trans-selective asymmetric cyclopropanation. A
study of the application of Co(II)-salen complex to
other carbene transfer reactions is now in progress
in our laboratory.
Experimental Section
General Methods
1
H NMR spectra were recorded at 400 MHz on a Bruker
DPX±400 or a JEOL GX±400 instrument. All signals were ex-
pressed as ppm down field from tetramethylsilane used as
an internal standard (d value in CDCl ). IR spectra were ob-
3
tained with a Shimadzu FTIR±8600 instrument. Optical rota-
tions were measured with a JASCO P±1020 polarimeter. Col-
umn chromatography was conducted on silica gel BW±
8
20MH, 70±200 mesh ASTM, available from Fuji Silysia Che-
mical Ltd. Preparative thin layer chromatography was per-
formed on 0.5 mm ´ 20 cm ´ 20 cm E. Merck silica gel plates
(60 F±254). Enantiomeric excesses were determined by
HPLC analysis using a Shimadzu LC±10AT±VP equipped
8
4
Adv. Synth. Catal. 2001, 343, 79±88

FULL PAPERS
with an appropriate optically active column, as described in
the footnotes of the corresponding Tables. Solvents were
dried and distilled shortly before use. Olefins, t-butyl a-di-
azoacetate, and ethyl a-diazoacetate were also distilled be-
fore use. The use of non-freshly distilled olefins and a-di-
azoacetates may be detrimental to the stereoselectivity of
the reaction. Reactions were carried out under an atmo-
sphere of nitrogen.
1123, 1043, 1018, 955, 891, 858, 797, 777, 748, 567, 503, 426
cm ; calcd. for C48H O N Co ´ 0.5 H O: C, 77.83; H, 5.03; N,
36 2 2 2
3.78%; found: C, 78.03; H, 5.08; N, 3.79%.
±1
Co(II)-salen complex 16
Brown solid; yield: 65%; IR (KBr): 3441, 3051, 2941, 2363,
2336, 1593, 1547, 1491, 1429, 1389, 1337, 1292, 1225, 1186,
±1
1148, 951, 868, 820, 752, 700, 673, 577, 546 cm ; calcd. for
Co ´ H O: C, 79.33; H, 4.76; N, 3.30%; found: C,
C
56
H
38
O
N
2 2
2
General Procedure for Co(II)-salen Complex: Prepara-
tion of Complex 6
79.51; H, 4.59; N, 3.39%.
To a solution of (1R,2R)-1,2-cyclohexanediamine (34.2 mg,
General Procedure for cis-Selective Asymmetric Cyclo-
propanation of Styrene with Complex 6
0
.3 mmol) in EtOH (10 mL) was added (R)-3-formyl-2-hy-
[
26]
droxy-2'-phenyl-1,1'-binaphthyl
(220 mg, 0.6 mmol) and
To a THF solution (5 mL) of Co(II)-salen complex 6 (44 mg,
50 lmol) was added a THF solution of N-methylimidazole
(0.2 mL, 0.5 M, 0.1 mmol) and the mixture was stirred for
2 min. Styrene (550 lL, 4.8 mmol) was added to this solution
and the mixture was stirred for another 3 min before being
treated with t-butyl a-diazoacetate (140 lL, 1.0 mmol). The
whole mixture was stirred for 24 h at room temperature
and then concentrated in vacuo. The residue was chromato-
graphed on silica gel (hexane-AcOEt = 1 : 0 to 9 : 1) to give a
98 : 2 mixture of cis- and trans-products in 89% yield. An ali-
quot of the mixture was submitted to preparative TLC (silica
the mixture was stirred for 6 h at room temperature. The re-
sulting light yellow precipitate was separated from the solu-
tion by filtration, and dried under vacuum. This precipitate
was added to the solution of Co(OAc)
which was prepared from Co(OAc)
0±80 °C under vacuum till its color turned from pink to pur-
2
(74.9 mg, 0.3 mmol)
2
´ 4 H O by heating at
2
7
ple in deaerated ethanol (8 mL) under nitrogen atmosphere.
The resulting purple brown precipitate was separated from
the solution by filtration, washed with degassed ethanol un-
der N
2
, and dried in vacuo to give the brown solid 6; yield:
69.1 mg (87%); IR (KBr): 3443, 3051, 2934, 2860, 2363,
603, 1547, 1491, 1450, 1331, 1298, 1225, 1186, 1148, 1028,
7
1
9
2
gel, hexane-i-Pr O = 4 : 1) to yield the cis-product which was
used for the determination of its enantiomeric excess by
HPLC analysis (98% ee).
±
1
52, 870, 822, 758, 700, 581, 544 cm ; calcd. for C60
O: C, 80.7; H, 5.08; N, 3.14%; found: C, 80.86; H,
.08; N, 3.09%.
Complexes 4, 7, 13±16 were prepared in the same manner
44 2 2-
H O N
Co ´ 0.5 H
2
5
(1R, 2S)-tert-Butyl cis-2-phenylcyclopropane-1-carbox-
ylate
2
0
as described for the synthesis of 6.
Colorless oil; yield: 36% (98% ee); [a]
D
±18.4° (c 0.34,
[17c]
24
CHCl
CHCl
3
). Lit.
[98% ee, (1S,2R)-isomer]; [a]
); H NMR (400 Hz): d = 7.29±7.16 (m, 5 H), 2.53 (ddd,
D
18.0° (c 0.73,
1
Co(II)-salen complex 4
3
Vermilion solid; yield: 98%; IR (KBr): 3445, 3065, 3032, 1597,
J = 7.5, 8.0, 8.5 Hz, 1 H), 1.98 (ddd, J = 5.5, 7.5, 8.0 Hz, 1 H),
1.64 (ddd, J = 5.0, 5.5, 7.5 Hz, 1 H), 1.24 (ddd, J = 5.0, 7.5,
8.5 Hz, 1 H), 1.13 (s, 9 H); IR (neat): 3582, 3059, 2976, 2930,
1722, 1603, 1456, 1389, 1366, 1290, 1254, 1211, 1169, 1148,
1
9
510, 1435, 1377, 1319, 1271, 1211, 1178, 1101, 1070, 1003,
±
1
51, 866, 791, 760, 698, 571, 548, 519 cm ; calcd. for
Cl Co: C, 54.67; H, 2.95; N, 4.55%; found: C,
4.49; H, 2.92; N, 4.61%.
C
28
H
18
O
N
2 2
4
±1
5
1082, 1032, 968, 901, 853, 795, 746, 721, 696 cm ; calcd. for
: C, 77.03; H, 8.31%; found: C, 77.01; H, 8.32%.
14 18 2
C H O
Co(II)-salen complex 7
Brown solid; yield: 76%; IR (KBr): 3445, 3051, 2936, 2860,
tert-Butyl
boxylate
cis-2-(4-chlorophenyl)cyclopropane-1-car-
2
1
363, 2336, 1593, 1547, 1491, 1447, 1427, 1327, 1296, 1225,
±
1
20
186, 1148, 953, 868, 818, 787, 756, 700, 583, 544 cm ; calcd.
Co ´ 0.5 H O: C, 80.7; H, 5.08; N, 3.14%; found:
Colorless oil; yield: 82% (95% ee); [a]
D
3
+4.4° (c 0.17, CHCl );
1
for C60
H
44
O
2
N
2
2
H NMR (400 Hz): d = 7.24±7.19 (m, 4 H), 2.47 (ddd, J = 7.3,
8.6, 9.3 Hz, 1 H), 1.99 (ddd, J = 5.7, 7.8, 9.3 Hz, 1 H), 1.59
C, 80.73; H, 4.90; N, 3.22%.
(ddd, J = 5.1, 5.7, 7.3 Hz, 1 H), 1.25 (ddd, J = 5.1, 7.8, 8.6 Hz,
Co(II)-salen complex 13
Red brown solid; yield: 84%; IR (KBr): 3447, 3053, 2909, 2363,
1 H), 1.18 (s, 9 H); IR (neat): 3005, 2978, 2932, 1726, 1599,
1495, 1454, 1391, 1367, 1292, 1254, 1213, 1169, 1147, 1093,
±1
2
1
5
2
336, 1587, 1545, 1491, 1448, 1425, 1389, 1323, 1225, 1186,
1034, 1014, 970, 899, 833, 777, 756, 710, 617 cm ; anal. calcd.
for C14 17ClO : C, 66.53; H, 6.78%; found: C, 6.55; H, 6.78%.
148, 1069, 1024, 953, 868, 816, 758, 700, 635, 611, 581, 542,
H
2
±
1
03, 436 cm ; calcd. for C68
46 2 2
H O N Co: C, 83.17; H, 4.72; N,
.85%; found: C, 82.81; H, 4.70; N, 2.84%.
tert-Butyl cis-2-(4-methoxyphenyl)cyclopropane-1-car-
boxylate
2
0
Co(II)-salen complex 14
Yellowish brown solid; yield: 86%; IR (KBr): 3439, 3049,
Colorless oil; yield: 81% (96% ee); [a]
D
3
+3.8° (c 0.38, CHCl );
1
H NMR (400 Hz): d = 7.18 (d, 2 H), 6.80 (d, 2 H), 3.77 (s,
3 H),2.46 (ddd, J = 7.0, 8.5, 9.0 Hz, 1 H), 1.93 (ddd, J = 5.5,
7.5, 9.0 Hz, 1 H), 1.57 (ddd, J = 5.0, 5.5, 7.0 Hz, 1 H), 1.21
(ddd, J = 5.0, 7.5, 8.5 Hz, 1 H), 1.17 (s, 9 H); IR (neat): 3585,
3003 2976, 2932, 2837, 1724, 1612, 1582, 1516, 1460, 1460,
3
1
007, 2932, 2858, 1591, 1553, 1445, 1421, 1337, 1227, 1190,
±
1
148, 1123, 955, 887, 860, 806, 781, 746, 567, 430 cm ; calcd.
Co: C, 79.04; H, 5.31; N, 3.69%; found: C,
9.03; H, 5.35; N, 3.79%.
40 2 2
for C50H O N
7
1
391, 1367, 1292, 1250, 1211, 1173, 1148, 1113, 1082, 1036,
±1
Co(II)-salen complex 15
970, 899, 833, 800, 779, 745 cm ; anal. calcd. for C15
20 3
H O :
Yellowish brown solid; yield: 80%; IR (KBr): 3443, 3049,
C, 72.55; H, 8.12%; found: C, 72.40; H, 8.16%.
2
932, 2856, 1595, 1551, 1423, 1352, 1329, 1227, 1188, 1150,
Adv. Synth. Catal. 2001, 343, 79±88
85

asc.wiley-vch.de
tert-Butyl
boxylate
cis-2-methyl-2-phenylcyclopropane-1-car-
Ethyl
ylate
cis-2-methyl-2-phenylcyclopropane-1-carbox-
20
24
Colorless oil; yield: 77% (96% ee); [a]
D
±40.8° (c 0.50,
Colorless oil; yield: 85% (96% ee); [a]
CHCl ); H NMR (400 MHz): d = 7.29±7.17 (m, 5 H), 3.85 and
3
D
±43.8° (c 0.48,
1
1
CHCl
3
); H NMR (400 Hz): d = 7.19±7.16 (m, 5 H), 1.80 (dd,
J = 7.5, 5.5 Hz, 1 H), 1.70 (dd, J = 5.5, 4.5 Hz, 1 H), 1.45 (s,
3.81 (ABqq, J = 10.9, 7.1 Hz, 2 H), 1.90 (dd, J = 7.8, 5.6 Hz,
1 H), 1.78 (dd, J = 5.6, 4.9 Hz, 1 H), 1.46 (s, 3 H), 1.15 (dd,
J = 7.8, 4.9 Hz, 1 H), 0.94 (t, J = 7.1 Hz, 3 H); IR (KBr): 3028,
2964, 2930, 2870, 1728, 1605, 1499, 1447, 1381, 1271, 1238,
3
3
1
5
H), 1.13 (s, 9H), 1.07 (dd, J = 7.5, 4.5 Hz, 1 H); IR (KBr):
061, 3007, 2974, 2930, 2868, 1722, 1605, 1499, 1446, 1389,
370, 1337, 1290, 1248, 1150, 1090, 978, 847, 781, 754, 700,
±
1
±1
52, 476 cm ; anal. calcd. for C15
H
20
O
2
: C, 77.55; H, 8.68%;
1167, 1024, 970, 905, 845, 768, 698, 478 cm ; anal. calcd. for
found: C, 77.43; H, 8.75%.
C
C
13
H
H
16
O
O
2
: C, 76.44; H, 7.90%; HRFABMS m/z calcd. for
+
13
17
2
(M +H): 205.1229; found: 205.1239.
tert-Butyl
ylate
cis-2-(2±naphthyl)cyclopropane-1-carbox-
General Procedure for trans-Selective Asymmetric Cy-
clopropanation of Styrene with Complex 9
2
0
Colorless crystals; yield: 94% (97 %ee); mp 82±83 °C; [a]
D
1
+
4
86.4° (c 0.72, CHCl
3
); H NMR (400 Hz): d = 7.79±7.71 (m,
To a THF solution (1 mL) of Co(II)-salen complex 9 (38 mg,
50 lmol) was added a THF solution of N-methylimidazole
(0.2 mL, 0.5 M, 0.1 mmol) and the mixture was stirred for
2 min. Styrene (550 lL, 4.8 mmol) was added to this solution
and the mixture was stirred for another 3 min before being
treated with t-butyl a-diazoacetate (140 mL, 1.0 mmol). The
whole mixture was stirred for 24 h at room temperature and
then concentrated in vacuo. The residue was passed
H), 7.46±7.39 (m, 3 H), 2.67 (ddd, J = 7.3, 8.6, 9.4 Hz, 1 H),
2
7
.05 (ddd, J = 5.7, 7.8, 9.4 Hz, 1 H), 1.77 (ddd, J = 5.0, 5.7,
.3 Hz), 1.33 (ddd, J = 5.0, 7.8, 8.6 Hz, 1 H), 1.05 (s, 3 H); IR
(
KBr): 3461, 3053, 2974, 2930, 2870, 1717, 1630, 1597, 1510,
1
7
7
456, 1391, 1367, 1215, 1153, 1096, 1053, 984, 887, 856, 829,
83, 748, 478 cm ; anal. calcd. for C18
.51%; found: C, 80.47; H, 7.50%.
±
1
20 2
H O : C, 80.56; H,
The cis-geometry of the major product obtained in the cy-
clopropanation of 12 with 6 as the catalyst was confirmed by
X-ray crystallographic analysis.
2
through a short silica gel column (hexane/i-Pr O = 1/0 to 4/
1) to give a mixture of tert-butyl trans- and cis-2-phenylcy-
[
27]
clopropane-1-carboxylates (218.0 mg) in quantitative yield.
1
The ratio of trans- and cis-isomers was determined by
H
(
1R, 2S)-Ethyl cis-2-phenylcyclopropane-1-carboxylate
NMR analysis to be 73 : 27. An aliquot of the mixture was sub-
mitted to preparative TLC (silica gel, hexane-i-Pr O = 4 : 1)
to yield the trans- and cis-isomers, separately. Their enantio-
meric excesses were determined as described in the foot-
notes of Table 5.
24
Colorless oil; yield: 99% (98% ee); [a]
CHCl
CHCl
D
±19.3° (c 0.48,
2
[
17c]
24
3
); Lit.
[88% ee (1S,2R)-isomer]; [a]
D
22.8° (c 0.43,
1
3
); H NMR (400 MHz): d = 7.26±7.19 (m, 5 H), 3.87 (q,
J = 7.3 Hz, 2 H), 2.58 (ddd, J = 7.4, 8.7, 9.3 Hz, 1 H), 2.07
ddd, J = 5.7, 7.8, 9.3 Hz, 1 H), 1.71 (ddd, J = 5.1, 5.7, 7.4 Hz,
(
1
3
1
7
H), 1.32 (ddd, J = 5.1, 7.8, 8.7 Hz, 1 H), 0.97 (t, J = 7.3 Hz,
H); IR (neat): 3059, 3026, 2982, 2933, 1728, 1605, 1499,
454, 1381, 1275, 1182, 1161, 1086, 1034, 961, 862, 827, 795,
(1R,2R)-tert-Butyl trans-2-phenylcyclopropane-1-car-
boxylate
2
0
Colorless oil; yield: 66% (98% ee); [a]
D
±247.6° (c 0.20,
±
1
[13b]
24
52, 721, 694, 476 cm , anal. calcd. for C12
H
14
O
2
: C, 75.76;
CHCl
0.73, CHCl
(ddd, J = 4.4, 6.4, 9.3 Hz, 1 H), 1.83 (ddd, J = 4.4, 5.4, 9.3 Hz),
.53 (ddd, J = 4.4, 5.4, 8.3 Hz, 1 H), 1.47 (s, 3 H),1.23 (ddd,
3
). Lit.
[93% ee (1S,2S)-isomer]; [a]
D
253.3° (c
+
1
H, 7.42%; HRFABMS m/z calcd. for C12
91.1057; found: 191.1058.
H
15
O
2
(M +H):
3
); H NMR (400 Hz): d = 7.29±7.08 (m, 5 H), 2.43
1
1
Ethyl cis±2±(4±chlorophenyl)cyclopropane±1±carbox-
ylate
J = 4.4, 6.3, 8.3 Hz, 1 H); IR (neat): 3030, 2978, 2932, 1720,
1605, 1499, 1458, 1400, 1367, 1340, 1285, 1253, 1215, 1155,
24
±1
Colorless oil; yield: 97% (96% ee); [a]
D
+6.2° (c 0.46 CHCl
3
);
1080, 1042, 1026, 935, 845, 783, 750, 696, 645, 409 cm ; anal.
1
H NMR (400 MHz): d = 7.24±7.18 (m, 4 H), 3.90 (q, J = 7.3,
calcd. for C14
8.34%.
18 2
H O : C, 77.03; H, 8.31%; found: C, 76.80; H,
2
7
H), 2.51 (ddd, J = 7.5, 8.6, 9.2 Hz, 1 H), 2.08 (ddd, J = 5.6,
.8, 9.2 Hz, 1 H), 1.67 (ddd, J = 5.1, 5.6, 7.5 Hz, 1 H), 1.33
(
ddd, J = 5.1, 7.8, 8.6 Hz, 1 H) 1.02 (t, J = 7.3 Hz, 3 H); IR
tert-Butyl
trans-2-(4-chlorophenyl)cyclopropane-1-
(
1
C
neat): 2983, 1726, 1495, 1387, 1277, 1184, 1161, 1094, 1034,
carboxylate
±
1
20
D
020, 962, 903, 833, 762, 706 cm
;
anal. calcd. for
Colorless crystals; yield: 75% (99% ee); mp 58±59 °C; [a]
±222.3° (c 0.29, CHCl ); H NMR (400 Hz): d = 7.23 (d,
3
1
12
H
13ClO : C, 64.15; H, 5.83%; found: C, 64.01; H, 5.86%.
2
J = 8.5 Hz, 2 H), 7.01 (d, J = 8.5 Hz, 2 H), 2.40 (ddd, J = 4.4,
6.4, 9.3 Hz, 1 H), 1.79 (ddd, J = 4.4, 5.4, 8.3 Hz), 1.53 (ddd,
J = 4.4, 5.4, 9.3 Hz, 1 H), 1.47 (s, 3 H), 1.19 (ddd, J = 4..4, 6.4,
8.3 Hz, 1 H); IR (KBr): 3003, 2982, 2937, 1904, 1717, 1651,
1493, 1450, 1394, 1366, 1335, 1302, 1254, 1217, 1151, 1094,
Ethyl cis-2-(4-methoxyphenyl)cyclopropane-1-carbox-
ylate
24
Colorless oil; yield: 95% (93% ee); [a]
D
3
+6.0° (c 0.39 CHCl );
1
H NMR (400 MHz): d = 7.18 (pseudo-d, J = 8.6 Hz, 2 H), 6.80
pseudo-d, J = 8.6 Hz, 2 H), 3.90 (q, J = 7.3 Hz, 2 H), 3.77 (s,
±1
(
1043, 1011, 926, 849, 816, 743, 523, 471 cm ; anal. calcd. for
17ClO : C, 66.53; H, 6.78%; found: C, 66.57; H, 6.77%.
3
7
H), 2.52 (ddd, J = 7.5, 8.7, 9.2 Hz, 1 H), 2.03 (ddd, J = 5.6,
.8, 9.2 Hz, 1 H), 1.66 (ddd, J = 5.0, 5.6, 7.5 Hz, 1 H), 1.30
C
14
H
2
(
(
1
4
ddd, J = 5.0, 7.8, 8.7 Hz, 1 H), 1.02 (t, J = 7.3 Hz, 3 H); IR
neat): 2984, 2837, 1726, 1612, 1581, 1516, 1462, 1381, 1296,
tert-Butyl trans-2-(4-methoxyphenyl)cyclopropane-1-
carboxylate
2
0
250, 1182, 1090, 1034, 960, 899, 833, 773, 675, 471,
Colorless oil; yield: 38% (94% ee); [a]
D
±238.0° (c 1.14,
±
1
1
11 cm ; anal. calcd. for C13
H
16
O
3
: C, 70.89; H, 7.32%;
CHCl ); H NMR (400 Hz): d = 7.02 (d, J = 8.5, 2 H), 6.81 (d,
3
found: C, 70.68; H, 7.35%.
J = 8.5, 2H), 2.40 (ddd, J = 3.9, 6.4, 9.3 Hz, 1 H), 1.74 (ddd,
J = 4.4, 5.4, 8.3 Hz, 1 H), 1.47 (ddd, J = 3.9, 5.4, 8.3 Hz, 1 H),
8
6
Adv. Synth. Catal. 2001, 343, 79±88

FULL PAPERS
1
3
1
4
.46 (s, 3H) 1.17 (ddd, J = 4.4, 6.4, 8.3 Hz, 1 H); IR (neat):
034, 3005, 2966, 2937, 2843, 1717, 1612, 1518, 1452, 1402,
367, 1344, 1294, 1254, 1217, 1086, 1030, 934, 864, 818, 752,
Acknowledgments
±
1
Financial support from a Grant-in-Aid for Scientific Research
Priority Areas, No. 706: Dynamic Control of Stereochemis-
20 3
72 cm ; anal. calcd. for C15H O : C, 72.55; H, 8.12%;
(
found: C, 72.49; H, 8.13%.
try) from the Ministry of Education, Science, Sports, and Cul-
ture, Japan, and from Banyu Pharmaceutical Co. Ltd. is
gratefully acknowledged.
tert±Butyl
carboxylate
Colorless oil; yield: 42% (99% ee); [a]
CHCl
trans±2±methyl±2±phenylcyclopropane±1±
2
0
D
±133.9° (c 0.10,
1
3
); H NMR (400 Hz): d = 7.33±7.18 (m, 5 H), 1.89 (dd,
J = 5.9, 8.3 Hz, 1 H), 1.51 (s, 3H), 1.49 (s, 9 H), 1.36 (dd,
J = 4.9, 5.9 Hz, 1 H), 1.33 (dd, 4.9, 8.3, 1 H); IR (neat): 3059,
References
2
1
9
978, 2932, 2880, 1948, 1871, 1722, 1680, 1645, 1605, 1578,
499, 1450, 1391, 1369, 1294, 1254, 1207, 1151, 1078, 972,
10, 847, 764, 739, 698, 434 cm ; anal. calcd. for C15H O :
20 2
[1] Catalytic Asymmetric Synthesis, 2nd ed.; I. Ojima, Ed.;
Wiley-VCH: New York, 2000.
±
1
[2] (a) H. Nozaki, H. Takaya, R. Noyori, Tetrahedron Lett.
C, 77.55; H, 8.68%; found: C, 77.37; H, 8.71%.
1
965, 2563±2567; (b) H. Nozaki, S. Moriuti, H. Takaya,
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c) H. Nozaki, S. Moriuti, H. Takaya, R. Noyori, Tetrahe-
(1R, 2R)-Ethyl trans-2-phenylcyclopropane-1-carbox-
(
ylate
2
4
dron 1968, 24, 3655±3669.
Colorless oil; yield: 69% (98% ee); [a]
CHCl
D
±291.2° (c 0.23,
1
[
3] (a) T. Aratani, Y. Yoneyoshi, T. Nagase, Tetrahedron
Lett. 1975, 1707±1710; (b) T. Aratani, Y. Yoneyoshi,
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Chem. 1985, 57, 1839±1844.
3
); H NMR (400 MHz): d = 7.30±7.09 (m, 5 H), 4.16 (q,
J = 7.5 Hz, 2 H), 2.52 (ddd, J = 4.2, 6.4, 9.2 Hz, 1 H), 1.90
ddd, J = 4.2, 5.3, 9.2 Hz, 1 H), 1.59 (ddd, J = 4.6, 5.3, 9.2 Hz,
(
1
3
1
8
H), 1.31 (ddd, J = 4.6, 6.4, 8.4 Hz, 1 H), 1.28 (t, J = 7.5 Hz,
H); IR (neat): 3030, 2984, 1724, 1661, 1605, 1499, 1458,
408, 1369, 1331, 1269, 1219, 1184, 1082, 1043, 1020, 941,
±
1
53, 783, 756, 698, 459 cm ; HRFABMS m/z calcd. for
[4] (a) M. P. Doyle, M. A. McKervey, T. Ye, Modern Cataly-
tic Methods for Organic Synthesis with Diazo Com-
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+
12 15 2
C H O (M +H): 191.1072; found: 191.1073.
Ethyl trans-2-(4-chlorophenyl)cyclopropane-1-carbox-
ylate
2
4
Colorless oil; yield: 78% (96% ee); [a]
D
±258.0° (c 0.78
); H NMR (400 MHz): d = 7.24 (d, J = 8.5 Hz, 2 H), 7.03
d, J = 8.5, 2 H) 4.17 (q, J = 7.0 Hz, 2 H), 2.48 (ddd, J = 4.1, 6.3,
.2 Hz, 1 H), 1.86 (ddd, J = 4.1, 5.3, 7.4 Hz, 1 H), 1.60 (ddd,
1
CHCl
3
(
9
J = 4.6, 6.3, 7.4 Hz, 1 H), 1.28 (t, J = 7.0 Hz, 3 H), 1.28 (ddd,
J = 4.6, 5.3, 9.2 Hz, 1 H); IR (neat): 2984, 2934, 2909, 1898,
1
1
C
726, 1497, 1450, 1406, 1394, 1327, 1269, 1219, 1186, 1094,
±
1
045, 1014, 949, 856, 818, 789, 737, 467 cm ; anal. calcd. for
13ClO : C, 64.15; H, 5.83%; found: C, 64.14; H, 5.88%.
12
H
2
Ethyl trans-2-(4-methoxyphenyl)cyclopropane-1-car-
boxylate
2
4
Colorless oil; yield: 67% (96% ee); [a]
D
±269.5° (c 0.28,
); H NMR (400 MHz): d = 7.03 (d, J = 8.5, 2 H), 6.82 (d,
J = 8.5 Hz, 2 H), 4.16 (q, J = 7.0 Hz, 2 H), 3.78 (s, 3 H), 2.48
ddd, J = 4.1, 6.4, 9.3 Hz, 1 H), 1.82 (ddd, J = 4.1, 5.2, 8.3 Hz,
1
CHCl
3
(
1
1
2
1
H), 1.28 (t, J = 7.0 Hz, 3 H), 1.55 (ddd, J = 4.6, 5.2, 9.3 Hz,
H), 1.25 (ddd, J = 4.6, 6.4, 8.3 Hz, 1 H); IR (neat): 2984,
837, 1724, 1614, 1582, 1518, 1450, 1408, 1331, 1294, 1252,
182, 1113, 1040, 947, 856, 824, 758, 463 cm ; anal. calcd.
: C, 70.89; H, 7.32%; found: C, 70.66; H, 7.35%.
±
1
[7] K. Ito, T. Katsuki, Tetrahedron Lett., 1993, 34, 2661±
2664.
16 3
for C13H O
[8] M. M.-C, Lo, G. C. Fu, J. Am. Chem. Soc, 1998, 120,
Ethyl trans-2-methyl-2-phenylcyclopropane-1-carbox-
ylate
10270±10271.
[9] H. Nishiyama, Y. Itoh, H. Matsumoto, S.-B. Park,
K. Itoh, J. Am. Chem. Soc. 1994, 116, 2223±2224.
24
Colorless oil; yield: 43% (93% ee); [a]
D
±193.3° (c 0.05,
); H NMR (400 MHz): d = 7.33±7.19 (m, 5 H), 4.20
ABqq, J = 8.5, 7.0 Hz, 2 H), 1.96 (dd, J = 5.9, 8.3 Hz, 1 H),
1
CHCl
3
[10] (a) M. Frauenkron, A. Berkessel, Tetrahedron Lett.
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(
1
8
2
1
.52 (s, 3 H), 1.43 (dd, J = 4.9, 5.9 Hz, 1 H), 1.41 (dd, J = 4.9,
.3 Hz, 1 H), 1.30 (t, J = 7.0 Hz, 3 H); IR (neat): 3059, 2984,
934, 1726, 1605, 1497, 1447, 1400, 1296, 1267, 1178, 1119,
±
1
090, 1063, 1022, 968, 908, 853, 762, 700, 482 cm ; HRFABMS
[11] (a) M. P. Doyle, B. D. Brandes, A. P. Kazala, R. J. Pie-
ters, M. B. Jarstfer, L. M. Watkins, C. T. Eagle, Tetrahe-
+
m/z calcd. for C13
17 2
H O (M +H): 205.1229; found: 205.1223.
Adv. Synth. Catal. 2001, 343, 79±88
87

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[
[
[22] X-ray structure analysis of second-generation Mn(III)-
salen complexes bearing chiral units at ethylenedi-
amine and binaphthyl parts disclosed that five-mem-
bered chelate rings including a manganese ion and an
ethylenediamine unit adopt a half-chair conformation
and that their salen ligands take stepped-conforma-
13] (a) T. Fukuda, T. Katsuki, Synlett, 1995, 825±826;
(
b) T. Fukuda, T. Katsuki, Tetrahedron 1997, 53, 7201±
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3
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14] (a) J. L. Maxwell, S. O'Malley, K. C. Brown, T. Kodad-
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Although the degree of folding of the salen li-
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and the relative configuration of the complexes, both
6
7
97±698; (c) H. Ishitani, K. Achiwa, Synlett, 1997, 781±
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(
R,R)- and (R,S)-complexes bend in a similar moder-
ate degree when they bear an aprotic donor ligand.
Based on this study, we assumed that both (R,R)- and
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(
R,S)-intermediate carbenoid species bearing NMI at
[
[
[
15] Y. N. Ito, T. Katsuki, Bull. Chem. Soc. Jpn. 1999, 72,
their apical site would adopt a moderately folded
stepped-conformation.
6
03±619.
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[
[
23] The structures of the intermediate carbenoid species
were schematically described on the assumption that
the salen ligand of Co(IV) species adopts a stepped-
1
1
165; (b) T. Uchida, R. Irie, T. Katsuki, Synlett, 1999,
793±1795; (c) T. Uchida, R. Irie, T. Katsuki, Tetrahe-
[19d, 19f, 19g, 25]
conformation.
24] It is reasonable to consider that carbenoid species de-
rived Co-salen complexes bearing a bulky substituent
at C3 and C3' do not allow substrate-approach from
the C3 and C3' side because of the short distance be-
tween the C3 and C3' substituents.
dron 2000, 56, 3501±3509.
[
[
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2
724; (c) M. Calligaris, D. Minichelli, G. Nardin,
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4610.
(
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27] Atomic coordinates, bond lengths and angles, and
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clopropane-1-carboxylate will be available on request
from the Cambridge Crystallographic Data Center, 12
Union Road, Cambridge, CB2 1EZ, U.K.
1
Acta Cryst. 1993, C 49, 1357±1359; (g) M. Hirotsu,
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000, 41, 3647±3651.
8
8
Adv. Synth. Catal. 2001, 343, 79±88