Asymmetric diethylzinc addition and phenyl transfer to aldehydes using chiral cis-cyclopropane-based amino alcohols

Article abstract of DOI:10.1016/j.tetasy.2007.03.006

A new series of amino alcohols with a chiral cyclopropane backbone have been developed and used in the catalytic asymmetric diethylzinc addition and phenyl transfer to various types of aldehydes. These cyclopropane-based chiral amino alcohols show high enantioselectivity in the addition of organozincs to aromatic and aliphatic aldehydes. For diethylzinc addition to aromatic and aliphatic aldehydes, up to 97% ee and 93% ee are obtained, respectively. For the phenyl transfer to aromatic aldehydes, the best enantioselectivity was 89% ee.

Full text of DOI:10.1016/j.tetasy.2007.03.006

Tetrahedron: Asymmetry 18 (2007) 734–741
Asymmetric diethylzinc addition and phenyl transfer to
aldehydes using chiral cis-cyclopropane-based amino alcohols
Jiangchun Zhong, Hongchao Guo, Mingan Wang, Mingming Yin and Min Wang*
Department of Applied Chemistry, China Agricultural University, Beijing 100094, PR China
Received 22 January 2007; accepted 6 March 2007
Abstract—A new series of amino alcohols with a chiral cyclopropane backbone have been developed and used in the catalytic asymmetric
diethylzinc addition and phenyl transfer to various types of aldehydes. These cyclopropane-based chiral amino alcohols show high
enantioselectivity in the addition of organozincs to aromatic and aliphatic aldehydes. For diethylzinc addition to aromatic and aliphatic
aldehydes, up to 97% ee and 93% ee are obtained, respectively. For the phenyl transfer to aromatic aldehydes, the best enantioselectivity
was 89% ee.
ꢀ 2007 Elsevier Ltd. All rights reserved.
CO2H
1. Introduction
PPh2
Cyclopropane is a fascinating subunit in organic synthesis.1
The smallest cycloalkane often acts as a basic structural
unit in a wide range of naturally occurring compounds2
and the prepared unnatural products.3 In these com-
pounds, probably the best known cyclopropane-containing
examples are the pyrethroid compounds, which are effec-
tive insecticides.4 Cyclopropanes have also been used as
versatile synthetic intermediates for the synthesis of more
functionalized cycloalkanes and acyclic compounds.5
Therefore, considerable efforts have been made to develop
efficient methods for the synthesis of cyclopropane-related
compounds, especially the enantioselective synthesis of
cyclopropane.6 A large variety of structurally diverse chiral
cyclopropane compounds have already been prepared and
applied extensively for many areas, but in asymmetric
catalysis, cyclopropane skeletons have received relatively
little attention and have rarely been used as chiral ligands
for asymmetric reactions. So far only a few chiral cyclopro-
pane-based ligands 1–4 have been reported (Fig. 1).7
Ph2P
R'2P
Ph2P
PPh2
1
2
SR
SR
PPh2
3
4
Figure 1. Chiral cyclopropane-based ligand.
other chiral ligand 2 with a cyclopropane ring as a chiral
backbone was reported by Minami et al.7b In the presence
of catalyst Pd–2, an asymmetric allylic alkylation was car-
ried out with 61% ee. Most recently, Molander et al. devel-
oped the chiral ligands 3 and 4, and used them in the
palladium-catalyzed allylic alkylation of 1,3-diphenyl-
propenyl acetate with dimethyl malonate, the correspond-
ing product can be obtained in high yield and with good
enantioselectivity (up to 93% ee). They also found that
the ligands based on trans-cyclopropane ring and metal
would form a dimeric complex with a bridging ligand,
which has been proven by the X-ray crystal structure of
the complex from ligand 1 and PdCl2.7c Dimeric or a mix-
ture of a monomeric nonchelate catalyst has a high flux-
ional environment that subsequently leads to lower
enantioselectivity. However, cis-ligands did chelate without
forming dimers. The results showed that cis-cyclopropane-
based ligand should have a better chelating capability.
In 1979, Colleuille et al. developed the first chiral cyclopro-
pane-based ligand 1.7a Using the cyclopropyl-based
diphosphine 1 as a chiral ligand in the rhodium-catalyzed
hydrogenation of dehydroamino acids, the corresponding
reduction product can be obtained in 23% ee. In 1992, an-
*
Corresponding author. Tel.: +86 010 62731356; fax: +86 010
62815939; e-mail: wangmincau@yahoo.com.cn
0957-4166/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2007.03.006

J. Zhong et al. / Tetrahedron: Asymmetry 18 (2007) 734–741
735
Based on these results, we designed and synthesized a new
type of 1,4-aminoalcohol ligand with cis-cyclopropane as a
chiral backbone, and have recently presented preliminary
results on the addition of diethylzinc to aromatic aldehydes
catalyzed by these amino alcohols.8,9 Herein, the full results
on the enantioselective diethylzinc addition to aromatic
and aliphatic aldehydes with enantiopure cyclopropane-
based amino alcohol ligands are provided.
We succeeded in obtaining single crystals of ligand 8b and
8c, both of which were characterized by X-ray crystallo-
graphic analysis. The absolute configurations of 8b and
8c were assigned as (1R,3S) by their crystal structure (Figs.
2 and 3). This is identical with the configuration of the
starting material 5. The –OH group and N atom are situ-
ated at the same side of cyclopropane backbone, and the
Although the reaction of the asymmetric addition of an
ethylzinc reagent to aldehydes has been well studied in re-
cent years, the enantioselective addition of diphenylzinc to
aldehydes is still challenging because the rapid competitive
uncatalyzed phenylation leads to the undesired
background reaction. Only a few results with high ee values
have been reported.10 Due to the importance of the
resulting chiral diarylmethanols as intermediates for the
synthesis of biologically and pharmaceutically active com-
pounds,10r we herein report our main efforts towards the
enantioselective phenyl transfer to aldehydes.
2. Results and discussion
Cyclopropane-based amino alcohol ligands were prepared
from commercially available (1R,5S)-4-hydroxy-6,6-di-
methyl-3-oxa-bicyclo-[3.1.0]hexan-2-one 5 in three simple
steps, which is a key intermediate from pyrethroid insecti-
cide and is quite inexpensive (Scheme 1).4 Compound 5 re-
acted with diazomethane in diethyl ether to quantitatively
give aldehydoester 6. Subsequent reductive amination of
6 by NaBH3CN and secondary amines in methanol affor-
ded a series of cis-cyclopropane aminoesters 7a–c in 90–
95% yield. A small amount of HCl can accelerate this reac-
tion. In this reaction, when the temperature is above 35 ꢁC,
trans-cyclopropane aminoesters can be formed as a side
product. Therefore, controlling the reaction temperature
is very important. Aminoesters 7a–c reacted with Grignard
reagent at ꢀ15 ꢁC to afford a series of aminoalcohol li-
gands 8a–c. The ee values of 8a–c are 98–99%. By recrystal-
lization, the ee values of 8a–c can be slightly improved.
Figure 2. ORTEP diagram of amino alcohol (1R,3S)-8b.
CH2N2
OHC
COOCH3
Et2O, rt
HO
O
O
5
6
HNR2, NaBH3CN
MeOH, rt
PhMgBr
THF, 0 o
C
COOCH3
R
7
N
N
a: R=
b: R=
c: R=
Ph
Ph
OH
R
N
O
8
Scheme 1. Synthesis of aminoalcohol ligands.
Figure 3. ORTEP diagram of amino alcohol (1R,3S)-8c.

736
J. Zhong et al. / Tetrahedron: Asymmetry 18 (2007) 734–741
˚
hydrogen bond was observed in C–O–Hꢁ ꢁ ꢁN–C (2.7 A) to
form a seven-membered ring. This clearly indicated that a
metal can easily chelate to both of the groups despite highly
rigid cyclopropane backbone.
for generally poor selectivity in the addition to aliphatic
aldehyde.
After our work on the diethylzinc addition to aromatic and
aliphatic aldehydes had been finished, we turned our atten-
tion to the phenyl transfer to the aldehydes. In order to ob-
tain excellent enantioselectivity in the addition of
diphenylzinc to aldehydes, it is a key point to reduce the
undesired background reaction from the rapid competitive
uncatalyzed phenylation. Bolm et al. found that less active
ethylphenylzinc can be used as a phenyl transfer reagent
and suppress the undesired background reaction, and
excellent enantioselectivity was realized.10e The ethylphe-
nylzinc can easily be prepared by mixing diphenylzinc
and diethylzinc, or alternatively by mixing arylboronic
acids with diethylzinc. The latter method is a better choice,
as it avoids using expensive and highly active diphenylzinc,
and arylzinc reagent can easily be prepared by this method.
At first, the diethylzinc addition to aromatic and aliphatic
aldehydes was attempted with enantiopure cyclopropane-
based amino alcohol ligands. Screening of ligands 8, 8b
and 8c demonstrated the best enantioselectivity. As shown
in Table 1, in all cases, the aldehydes were completely con-
sumed after 48 h under the reaction conditions. As shown
by entries 1–14, the addition of diethylzinc to aromatic
aldehydes proceeded in high yields and with enantioselec-
tivities in the range of 95–97% ee. Compared with the cases
of aromatic aldehydes, ligands 8b and 8c give lower selec-
tivity in the ethylation of aliphatic and a,b-unsaturated
aldehydes (Table 1, entries 15–26). For linear aldehydes,
the catalyst displayed moderate enantioselectivity (entries
15–26). The best 93% ee was obtained with cyclohexane-
carbaldehyde (entries 25–26). This is an encouraging result
In exploring this reaction, ligands 8a–c were screened for
the phenylation of 4-methylbenzaldehyde by using the eth-
ylphenylzinc reagent. First, the phenylzinc reagent was pre-
pared from phenylboronic acid and diethylzinc in toluene
at 60 ꢁC for 12 h according to Bolm’s protocol,12d then
10 mol % of 8 and a polyether (DiMPEG) were added into
the mixture. Subsequently 4-methylbenzaldehyde was in-
jected. As shown in Table 2, the phenyl transfer to 4-meth-
ylbenzaldehyde proceeded smoothly at 20 ꢁC in 12 h with
8c as the chiral ligand to give diarylmethanol in 90% yield
but only in 72% ee (Table 2, entry 1). The same as in the
case of diethylzinc addition to aldehydes, the reaction tem-
perature is especially important for high enantioselectivity.
When the temperature was lowered to 0 and ꢀ20 ꢁC, a
clear improvement in the enantioselectivity was obtained
(Table 2, entry 1 vs entries 2 and 3) and the corresponding
ee increased to 85%. When the temperature continued to be
Table 1. Diethylzinc addition to aromatic aldehydes and aliphatic by
using ligands 8b and 8ca
O
OH
Et2Zn
ligands 8b or 8c
R
H
R
Entry Aldehyde
Ligand Yieldb (%) eec (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Benzaldehyde
2-MeOC6H4CHO
3-MeOC6H4CHO
4-MeOC6H4CHO
2-ClC6H4CHO
4-ClC6H4CHO
1-Naphthaldehyde
n-Hexanal
8b
8c
8b
8c
8b
8c
8b
8c
8b
8c
8b
8c
8b
8c
8b
8c
8b
8c
8b
8c
8b
8c
8b
8c
87
90
90
88
93
92
89
90
65
60
77
80
94
93
88
82
75
82
66
70
88
82
83
85
92
90
96
96
95
95
95
96
96
96
90
94
96
96
96
97
70
65
72
66
72
66
66
61
75
72
93
93
Table 2. Enantioselective phenyl transfer to 4-methylbenzaldehyde using
ligands 8a–ca
OH
CHO
Et2Zn, PhB(OH)2
10mol % 8 toluene
Me
Me
n-Pentanal
Entry
Ligands
Temp (ꢁC)
Time (h)
Yieldb (%)
eec (%)
n-Heptanal
1
2
3
4
5d
6e
7
8c
8c
8c
8c
8c
8c
8b
8a
20
0
12
12
48
48
48
48
48
48
90
91
86
85
88
88
85
86
72
81
85
84
79
82
87
81
n-Nonanal
ꢀ20
ꢀ30
ꢀ20
ꢀ20
ꢀ20
ꢀ20
trans-Cinnamaldehyde
Cyclohexanecarbaldehyde 8b
8c
8
a Reaction conditions: Et2Zn (220 mol %), ligand (10 mol %), hexane as a
solvent, ꢀ15 ꢁC, 48 h.
a Conditions: 2 equiv of PhB(OH)2 and 6 equiv of Et2Zn were used with
respect to ArCHO.
b Isolated yield.
b Isolated yield after flash chromatography.
c For aromatic alcohols, determined by HPLC analysis on a chiral Daicel
OD-H column or by GC analysis on a chiral cyclodextrin capillary
column; for aliphatic alcohols, determined by HPLC analysis of the
corresponding 3,5-dinitrobenzoate of alcohol products on the Chiral
Daicel OD-H column. Absolute configuration of major enantiomer was
assigned as (R)-configuration by the comparison of specific rotation with
literature data.
c Determined by HPLC analysis using a chiral column (Daicel Chiralcel
OD-H; hexane/i-PrOH = 90:10), and the absolute configuration of the
major enantiomer was assigned as (R) by the comparison of elution
order on HPLC with the reported value.
d No DiMPEG was added.
e The ligand was pretreated with Et2Zn.

J. Zhong et al. / Tetrahedron: Asymmetry 18 (2007) 734–741
737
lowered to ꢀ30 ꢁC, the ee remained nearly the same (Table
4. Experimental
2, entry 3 vs entry 4). According to the results reported by
Ito, Katsuki and Uang et al., the use of DiMPEG as an
additive deteriorated the enantioselectivity.10g–i Con-
versely, in our case, the use of DiMPEG as an additive im-
proved enantioselectivity. When the reaction was carried
out with DiMPEG, the ee increased from 79% to 84% (Ta-
ble 2, entries 3 and 5). To optimize the reaction conditions,
we also pretreated 8c with Et2Zn, which has been found to
improve enantioselectivity.10i However, in our case, the ee
value decreased slightly from 85% to 82% (Table 2, entry
3 vs entry 6). Under the optimized conditions, ligands 8a
and 8b were examined in the same reaction. Ligand 8b
afforded the best 87% ee with 85% yield (Table 2, entry 7).
4.1. General
Melting points were determined using a Yanagimoto appa-
ratus and are uncorrected. The optical rotations were mea-
sured with Perkin–Elmer PE-341 polarimeter. H and 13C
1
NMR spectra were recorded in CDCl3 using a Bruker
500 MHz. All chemical shifts are quoted in parts per mil-
lion relative to tetramethylsilane (d, 0.00 ppm), and cou-
pling constants (J) are measured in Hertz. Mass spectra
were recorded on an Agilent instrument using the TOFMS
technique. Infrared spectra were recorded using a Bruker
Tensor 27 spectrometer. The reactions were carried out un-
der nitrogen or argon using Schlenk technique when neces-
sary. High Performance Liquid Chromatography was
conducted on Agilent 1100 using chiral column Diacel Chi-
ralcel OD-H. Gas Chromatography was conducted on Lu-
Nan 6800 series with FID detector using chiral column
CYCLODEX-B, 30 m · 0.25 mm I.D. (Agilent Technolo-
gies, USA). Retention time is given in minutes.
Under the optimized reaction conditions, various aromatic
aldehydes were studied for the phenylation with 10 mol %
of 8b at ꢀ20 ꢁC. High yields and good enantiomeric ex-
cesses in the range of 72–89% ee were accomplished with
these aromatic aldehydes (Table 3). Electron-deficient and
electron-rich aromatic aldehydes demonstrated different
enantioselectivity in this reaction. Generally, electron-rich
aromatic aldehydes showed the high enantioselectivity. 2-
Methoxybenzaldehyde gave the best enantioselectivity at
89% ee (Table 3, entry 4).
4.2. (1R,3S)-Methyl 3-formyl-2,2-dimethylcyclopropane-
carboxylate 6
(1R,5S)-4-Hydroxy-6,6-dimethyl-3-oxa-bicyclo[3.1.0]-hex-
an-2-one 5 (2.84 g, 20 mmol) was dissolved in a mixture of
30 mL of Et2O and 5 mL of MeOH. This solution was
cooled to 0 ꢁC and a solution of diazomethane in ether
was added slowly with stirring, until the solution stopped
bubbling and the color of the solution remained yellow.
The solution was slowly allowed to warm to room temper-
ature without additional heating. The reaction mixture was
concentrated under reduced pressure. The crude product
was passed through a silica gel column (hexane/ethyl ace-
Table 3. Enantioselective phenyl transfer to aromatic aldehydes using
ligand 8ba
O
Et2Zn, PhB(OH)2
OH
Ph
10 mol % 8b toluene
H
R
R
Entry
Aldehyde
Yieldb (%)
eec (%)
1
2
3
4
5
6
7
2-BrC6H4CHO
3-BrC6H4CHO
2-ClC6H4CHO
2-MeOC6H4CHO
trans-Cinnamaldehyde
1-Naphthaldehyde
2-Naphthaldehyde
83
82
90
88
87
80
85
79
83
72
89
84
88
79
tate = 6/1) to afford 6 as a colorless oil (2.9 g, 93% yield).
18
½aꢂD ¼ ꢀ73:4 (c 0.99, CHCl3); IR (neat) 2957, 1731, 1701,
1439, 1379, 1200, 1137, 1119, 839 cmꢀ1
;
1H NMR
(500 MHz, CDCl3): d 1.27 (s, 3H), 1.55 (s, 3H), 1.83–1.86
(m, 1H), 2.12 (d, 1H, J = 9.5 Hz), 3.71 (s, 3H), 9.75 (d,
1H, J = 9.5 Hz); 13C NMR (125 MHz, CDCl3): d 15.5,
28.3, 29.8, 36.1, 40.9, 52.2, 170.4, 200.4; HRMS (TOF):
m/z calcd for C8H13NO3 [M+H]+: 157.0865, found:
157.0865.
a Conditions: 2 equiv of PhB(OH)2 and 6 equiv of Et2Zn were used with
respect to ArCHO, toluene as solvent, ꢀ20 ꢁC, 48 h.
b Isolated yield.
c Determined by HPLC on a chiral column (Daicel Chiralcel OD-H), and
the absolute configuration of the major enantiomer was assigned as (R)
by the comparison of elution order of HPLC with the reported value.
4.3. General procedure for the preparation of cis-cyclopro-
pane aminoesters from cis-cyclopropane aldehydoester
3. Conclusions
To a solution of 60 mmol of a secondary amine in 50 mL
of methanol was added 4 mL (20 mmol) of 5 M HCl–
methanol, followed by 3.12 g (20 mmol) of 6 and 1 g
(16 mmol) of NaBH3CN. The resulting solution was stir-
red at room temperature for 16 h. Concentrated HCl was
then added until pH <2, and the methanol was removed
under reduced pressure. The residue was taken up in
15 mL of water and extracted with three 20 mL portions
of ether. The aqueous solution was brought to pH >10
with 20% NaOH (aq), and extracted with ether
(5 · 15 mL). The combined extracts were dried over
MgSO4 and concentrated under reduced pressure to give
7a–c with 90–95% yields.
In conclusion, a new type of cis-cyclopropane-based amino
alcohol ligands has been developed. The ligands promoted
the addition of diethylzinc and phenylzinc reagents to aro-
matic and aliphatic aldehydes under mild conditions to af-
ford the corresponding secondary alcohols in high yield
with moderate to excellent enantioselectivity. These results
showed that the chiral cyclopropane-based ligand is prom-
ising in asymmetric catalysis and deserves more attention.
Research on the synthesis of other chiral cyclopropane-
based ligands and their application in other types of asym-
metric reactions is being carried out in this laboratory and
will be reported in due course.

738
J. Zhong et al. / Tetrahedron: Asymmetry 18 (2007) 734–741
4.3.1.
(1R,3S)-Methyl
2,2-dimethyl-3-((pyrrolidin-1-
(500 MHz, CDCl3): d 0.91 (s, 3H), 0.92–1.02 (m, 1H),
18
yl)-methyl)cyclopropanecarboxylate 7a. Dense oil, ½aꢂD
ꢀ4:3 (c 1.62, EtOH); IR (neat) 2952, 2782, 1729, 1437,
1383, 1355, 1175, 1140, 1088, 852 cmꢀ1 1H NMR
(500 MHz, CDCl3): d 1.19 (s, 3H), 1.23 (s, 3H), 1.30–1.34
(br s, 4H), 1.53 (d, 1H, J = 9.0 Hz), 1.77 (br s, 4H), 2.52
(br s, 1H), 2.71–2.75 (m, 1H), 2.85–2.89 (m, 1H), 3.64 (s,
3H); 13C NMR (125 MHz, CDCl3): d 14.5, 23.4, 25.1,
28.5, 28.7, 32.4, 50.0, 51.1, 53.9, 172.2; HRMS (TOF):
m/z calcd for C12H22NO2 [M+H]+: 212.1651, found:
212.1642.
¼
1.22 (s, 3H), 1.61–1.64 (m, 2H), 1.65–1.74 (m, 3H), 2.40–
2.91 (m, 5H), 2.93–2.95 (m, 1H), 7.09–7.16 (m, 2H),
7.22–7.28 (m, 4H), 7.50–7.56 (m, 4H), 8.09(br s, 1H); 13C
NMR (125 MHz, CDCl3): d 15.5, 20.1, 23.3, 26.5, 30.1,
38.3, 51.3, 52.9, 125.3, 125.7, 125.9, 127.6, 127.7, 149.1,
152.1; HRMS (TOF): m/z calcd for C23H30NO [M+H]+:
336.2327, found: 336.2322.
;
4.4.2.
((1R,3S)-2,2-Dimethyl-3-((piperidin-1-yl)methyl)-
cyclopropyl)diphenylmethanol 8b. Colorless needles, mp
18
162–163 ꢁC; ½aꢂD ¼ þ167:6 (c 0.82, CHCl3); IR (KBr)
4.3.2.
yl)-methyl)cyclopropanecarboxylate 7b. Dense oil, ½aꢂD
ꢀ7:1 (c 0.98, CHCl3); IR (neat) 2935, 2854, 1729, 1437,
1375, 1174, 1153, 1133, 1089, 849 cmꢀ1 1H NMR
(500 MHz, CDCl3): d 1.18 (s, 3H), 1.21 (s, 3H), 1.26–1.28
(m, 1H), 1.43 (br s, 2H), 1.52 (d, 1H, J = 9.0 Hz), 1.58
(br s, 4H), 2.40 (br s, 4H), 2.58–2.62 (m, 1H), 2.71–2.74
(m, 1H), 3.63 (s, 3H); 13C NMR (125 MHz, CDCl3): d
14.5, 24.4, 25.0, 26.1, 28.5, 28.7, 31.3, 51.1, 53.3, 54.2,
172.1; HRMS (TOF): m/z calcd for C13H24NO2 [M+H]+:
226.1807, found: 226.1810.
(1R,3S)-Methyl
2,2-dimethyl-3-((piperidin-1-
18
3420, 2937, 1444, 1370, 1305, 1194, 1124, 1097, 1062,
¼
1
1028, 1010, 985, 881, 773, 750, 700, 636 cmꢀ1; H NMR
(500 MHz, CDCl3): d 0.89 (s, 3H), 1.00–1.05 (m, 1H),
1.16 (s, 3H), 1.20–1.37 (m, 6H), 1.84 (d, 1H, J = 9.0 Hz),
2.46–2.61 (m, 6H), 7.09–7.14 (m, 2H), 7.22–7.26 (m, 4H),
7.52–7.60 (m, 4H), 7.78 (br s, 1H); 13C NMR (125 MHz,
CDCl3): d 15.4, 20.0, 24.1, 25.1, 25.3, 30.3, 37.3, 53.5,
54.7, 125.63, 125.66, 125.74, 127.5, 127.8, 149.3, 151.9;
HRMS (TOF): m/z calcd for C24H32NO [M+H]+:
350.2484, found: 350.2479.
;
4.3.3. (1R,3S)-Methyl 2,2-dimethyl-3-(morpholinomethyl)-
4.4.3.
((1R,3S)-2,2-Dimethyl-3-(morpholinomethyl)cyclo-
18
cyclopropanecarboxylate 7c. Dense oil, ½aꢂD ¼ þ15:4 (c
propyl)diphenylmethanol 8c. Colorless needles, mp 156–
18
0.88, CHCl3); IR (neat) 2952, 2854, 1727, 1456, 1374,
157 ꢁC; ½aꢂD ¼ þ158:5 (c 0.93, CHCl3); IR (KBr) 3430,
1
1177, 1117, 1087, 1010, 866 cmꢀ1; H NMR (500 MHz,
2822, 1449, 1371, 1299, 1272, 1192, 1113, 1070, 1031,
1014, 920, 864, 778, 752, 706, 637 cmꢀ1
;
1H NMR
CDCl3): d 1.18 (s, 3H), 1.22 (s, 3H), 1.24–1.27 (m, 1H),
1.54 (d, 1H, J = 9.0 Hz), 2.47 (br s, 4H), 2.64–2.68 (m,
1H), 2.74–2.78 (m, 1H), 3.64 (s, 3H), 3.70 (br s, 4H); 13C
NMR (125 MHz, CDCl3): d 14.5, 25.0, 28.4, 28.7, 30.7,
51.1, 52.9, 53.4, 67.1, 172.0; HRMS (TOF): m/z calcd for
C12H22NO3 [M+H]+: 228.1600, found: 228.1589.
(500 MHz, CDCl3): d 0.94 (s, 3H), 0.93–1.05 (m, 1H),
1.17 (s, 3H), 1.88 (d, 1H, J = 9.0 Hz), 2.35 (br s, 2H),
2.52 (br s, 2H), 2.56–2.60 (m, 1H), 2.65–2.69 (m, 2H),
3.30 (b, 2H), 3.48–3.52 (m, 2H), 7.11–7.15 (m, 2H), 7.24–
7.27 (m, 4H), 7.51–7.61 (m, 4H); 13C NMR (125 MHz,
CDCl3): d 15.3, 20.1, 24.5, 30.3, 37.1, 52.6, 54.6, 66.2,
125.4, 125.6, 125.8, 126.2, 127.7, 127.9, 148.9, 151.6;
HRMS (TOF): m/z calcd for C23H30NO2 [M+H]+:
352.2277, found: 352.2272.
4.4. General procedure for the synthesis of cis-cyclopropane
aminoalcohol 8a–c
Magnesium (0.6 g, 25.0 mmol) was added to 20 mL of
anhydrous THF. A solution of bromobenzene (3.14 g,
20 mmol in 10 mL of THF) was added dropwise into the
above mixture. Once the reaction began, the rest of the
bromobenzene solution was added at a rate that main-
tained a gentle reflux. When the addition of the bromobenz-
ene solution was complete, the mixture was refluxed for
20 min, and was then cooled to ꢀ15 ꢁC. Compound 7
(5 mmol) was dissolved in 5 mL of anhydrous THF and
added to the prepared Grignard mixture. After the solution
of compound 7 had been added, the resulting mixture was
stirred at room temperature for an additional 12 h. The
reaction was quenched with saturated NH4Cl (aq), and
the mixture was extracted several times with Et2O. The or-
ganic phases were combined, dried over MgSO4 and con-
centrated under reduced pressure. The residual yellow
solid was purified by flash chromatography (hexane/ethyl
acetate = 1/2) to yield 9a–b as colorless crystals.
4.5. X-ray crystal structure data for (1R,3S)-8b and 8c
Compound 8b: C24H31NO, Mr = 349.50, triclinic, P1,
˚
a = 6.1917(12), b = 8.8540(18), c = 9.7155(19) A; a =
92.53(3)ꢁ,
b = 95.90(3)ꢁ,
c = 105.29(3)ꢁ;
V =
3
˚
509.63(17) A ; 2.39ꢁ < 2h < 27.64ꢁ;
q
calc = 1.273 g cmꢀ3
,
Z = 1, F(000) = 190; Final R1 = 0.0524, wR2 = 0.1447,
all data, R1 = 0.0642, wR2 = 0.1550.
Compound 8c: C23H29NO2, Mr = 351.47, triclinic, P1,
˚
a = 6.2009(12), b = 8.7144(17), c = 9.6164(19) A; a =
92.38(3)ꢁ,
b = 98.64(3)ꢁ,
c = 104.91(3)ꢁ;
V =
3
˚
494.70(17) A ; 2.15ꢁ < 2h < 27.45ꢁ;
q
calc = 1.180 g cmꢀ3
,
Z = 1, F(000) = 190; Final R1 = 0.0473, wR2 = 0.1270,
all data, R1 = 0.0712, wR2 = 0.1398.
CCDC-618048 and CCDC-618049 contain the supplemen-
tary crystallographic data for 8b and 8c, respectively. These
data can be obtained free of charge via www.ccdc.cam.
ac.uk/conts/retrieving.html [or from the CCDC, Cam-
bridge, CB21EZ, UK; fax: (+44)-1223–336–033; or e-mail:
deposit@ccdc.cam.ac.uk].
4.4.1.
((1R,3S)-2,2-Dimethyl-3-((pyrrolidin-1-yl)methyl)-
cyclopropyl)diphenylmethanol 8a. Colorless needles, mp
18
112–113 ꢁC; ½aꢂD ¼ þ14:1 (c 1.51, CHCl3); IR (KBr)
3370, 2949, 1446, 1371, 1346, 1319, 1278, 1184, 1090,
1066, 1032, 956, 876, 768, 748, 700, 636 cmꢀ1; H NMR
1

J. Zhong et al. / Tetrahedron: Asymmetry 18 (2007) 734–741
739
26
4.6. General procedure for diethylzinc addition to aldehydes
4.6.7. (R)-1-(1-Naphthalenyl)-1-propanol. ½aꢂD ¼ þ60:3 (c
1.11, CHCl3). {lit.11b [a]D = +61.1 (c 0.442, benzene) for
77% ee (R)}; 97% ee (R) by HPLC analysis (Chiralcel
OD-H column, hexane/2-propanol = 80/20, 1.0 mL/min,
254 nm UV detection), tR = 6.4 min for (S) and
tR = 10.9 min for (R).
The chiral ligand (0.1 mmol) was dissolved in hexane
(3 mL), cooled to ꢀ15 ꢁC, and diethylzinc (1.5 mL of
1.5 M of toluene solution, 2.2 mmol) was injected. After
the mixture was stirred for 20 min, benzaldehyde (0.1 g,
1 mmol) was added dropwise via a syringe, and the mixture
stirred for the corresponding reaction time under N2. The
reaction was quenched by the addition of a saturated aque-
ous solution of NH4Cl (10 mL). The mixture was then ex-
tracted with Et2O (3 · 15 mL). The combined organic
phases were dried and concentrated in vacuo. The crude
products were purified by flash column chromatography
(hexane/EtOAc). The ee values of the alcohol products
were determined by HPLC on a Chiralcel OD-H column
(i-PrOH/hexane) or by GC analysis on a chiral cyclodex-
trin capillary column. The absolute configuration of the
major enantiomer was assigned by the comparison of opti-
cal rotation with literature data.
26
4.6.8. (R)-Heptan-3-ol. ½aꢂD ¼ ꢀ4:9 (c 0.68, CHCl3).
{lit.11d [a]D = +5.8 (c 0.442, CHCl3) for 95% ee (S)}; 72%
ee (R) by HPLC analysis of the corresponding derivative
3,5-dinitrobenzoate by OD-H column (Chiralcel OD-H
column, hexane/2-propanol = 95/5, 1.0 mL/min, 254 nm
UV detection), tR = 10.2 min for (S) and tR = 11.4 min
for (R).
26
4.6.9. (R)-Octan-3-ol. ½aꢂD ¼ ꢀ6:5 (c 0.80, CHCl3). {lit.11e
[a]D = ꢀ8.9 (c 6.12, CHCl3) for 98% ee (R)}; 70% ee (R) by
HPLC analysis of the corresponding derivative 3,5-dini-
trobenzoate by OD-H column (Chiralcel OD-H column,
hexane/2-propanol = 95/5, 1.0 mL/min, 254 nm UV detec-
tion), tR = 11.3 min for (S) and tR = 12.6 min for (R).
26
4.6.1. (R)-1-Phenyl-1-propanol. ½aꢂD ¼ þ40:3 (c 1.21,
CHCl3). {lit.11a [a]D = ꢀ33.0 (c 3.35, CHCl3) for 80% ee
(S)}; 96% ee (R) by HPLC analysis (Chiralcel OD-H col-
umn, hexane/2-propanol = 95/5, 1.0 mL/min, 254 nm UV
detection), tR = 8.4 min for (R) and tR = 13.2 min for (S).
26
4.6.10. (R)-Nonan-3-ol. ½aꢂD ¼ ꢀ9:0 (c 0.68, CHCl3).
{lit.11f [a]D = +9.1 (c 7.2, CHCl3) for 88% ee (S)}; 72% ee
(R) by HPLC analysis of the corresponding derivative
3,5-dinitrobenzoate by OD-H column (Chiralcel OD-H
column, hexane/2-propanol = 95/5, 1.0 mL/min, 254 nm
UV detection), tR = 9.5 min for (S) and tR = 10.6 min for
(R).
26
4.6.2. (R)-1-(2-Methoxyphenyl)-1-propanol. ½aꢂD ¼ þ23:7
(c 1.40, CHCl3). {lit.11b [a]D = +44.6 (c 0.451, toluene)
for 78% ee (R)}; 95% ee (R) by GC analysis (CYCLO-
DEX-B column, N2 = 1.0 mL/min, DET = 250 ꢁC,
INJ = 240 ꢁC, OVEN = 160 ꢁC), tR = 11.7 min for (S)
and tR = 13.3 min for (R).
26
4.6.11. (R)-Undecan-3-ol. ½aꢂD ¼ ꢀ6:3 (c 0.41, CHCl3).
{lit.11g [a]D = +5.2 (c 1, CHCl3) for 84% ee (S)}; 66% ee
(R) by HPLC analysis of the corresponding derivative
3,5-dinitrobenzoate by OD-H column (Chiralcel OD-H
column, hexane/2-propanol = 95/5, 1.0 mL/min, 254 nm
UV detection), tR = 8.6 min for (S) and tR = 9.6 min for
(R).
26
4.6.3. (R)-1-(3-Methoxyphenyl)-1-propanol. ½aꢂD ¼ þ40:3
(c 1.21, CHCl3). {lit.11b [a]D = +23.3 (c 0.498, benzene)
for 81% ee (R)}; 95% ee (R) by HPLC analysis (Chiralcel
OD-H column, hexane/2-propanol = 95/5, 1 mL/min,
254 nm UV detection), tR = 16.0 min for (R) and tR =
19.8 min for (S).
26
4.6.12. (R)-(E)-1-Phenylpent-1-en-3-ol. ½aꢂD ¼ þ18:4 (c
0.61, CHCl3). {lit.11g [a]D = ꢀ13.2 (c 2.1, Et2O) for 48%
ee (S)}; 75% ee (R) by HPLC analysis (Chiralcel OD-H col-
umn, hexane/2-propanol = 90/10, 1.0 mL/min, 254 nm UV
detection), tR = 7.6 min for (R) and tR = 11.4 min for (S).
26
4.6.4. (R)-1-(4-Methoxyphenyl)-1-propanol. ½aꢂD ¼ þ38:9
(c 1.23, CHCl3). {lit.11b [a]D = +28.5 (c 0.534, benzene)
for 83% ee (R)}; 96% ee (R) by HPLC analysis (Chiralcel
OD-H column, hexane/2-propanol = 95/5, 1.0 mL/min,
254 nm detection), tR = 10.7 min for (R) and tR = 12.9 min
for (S).
26
4.6.13. (R)-1-Cyclohexylpropan-1-ol. ½aꢂD ¼ þ5:4 (c 0.61,
CHCl3). {lit.11g [a]D = ꢀ3.1 (c 0.47, CHCl3) for 89% ee
(S)}; 93% ee (R) by HPLC analysis of the corresponding
derivate of 3,5-dinitrobenzoate by OD-H column (Chiral-
cel OD-H column, hexane/2-propanol = 98/2, 1.0 mL/
min, 254 nm UV detection), tR = 31.7 min for (S) and
tR = 33.7 min for (R).
26
4.6.5. (R)-1-(2-Chlorophenyl)-1-propanol. ½aꢂD ¼ þ42:5 (c
1.62, CHCl3). {lit.11c [a]D = +37.1 (c 4, CHCl3) for 79%
ee (R)}; 95% ee (R) by GC analysis (CYCLODEX-B col-
umn, N2 = 1.0 mL/min, DET = 250 ꢁC, INJ = 240 ꢁC,
OVEN = 160 ꢁC ), tR = 12.0 min for (R) and tR = 12.8 min
for (S).
4.7. General procedure for phenyl transfer reaction
A flame dried Schlenk tube containing toluene (2 mL),
phenylboronic acid (122 mg, 1 mmol), and diethylzinc
(3.0 mmol, 1.5 M solution in toluene) was heated at 60 ꢁC
for 12 h. After the flask was cooled to room temperature,
the mixture was added into another flask containing 9c
(17.5 mg, 0.05 mmol) and DiMPEG (0.1 g, 0.05 mmol) in
toluene (1 mL), and was stirred for 15 min. It was cooled
to ꢀ20 ꢁC, and a solution of 4-tolualdehyde (60 mg,
26
4.6.6. (R)-1-(4-Chlorophenyl)-1-propanol. ½aꢂD ¼ þ30:6 (c
2.08, CHCl3). {lit.11b [a]D = +19.8 (c 0.479, benzene) for
82% ee (R)}; 96% ee (R) by HPLC analysis (Chiralcel
OD-H column, hexane/2-propanol = 97/3, 1.0 mL/min,
254 nm UV detection), tR = 7.4 min for (S) and tR =
7.8 min for (R).

740
J. Zhong et al. / Tetrahedron: Asymmetry 18 (2007) 734–741
2. (a) Djerassi, C.; Doss, G. A. New J. Chem. 1990, 14, 713–719;
(b) Salaun, J. Curr. Med. Chem. 1995, 2, 511–542; (c) Salaun,
0.5 mmol) in toluene (1 mL) was added with stirring. After
48 h at ꢀ20 ꢁC, the reaction was quenched with saturated
aqueous ammonium chloride and then extracted with
Et2O (3 · 10 mL). The combined organic phases were dried
and concentrated in vacuo. The crude products were puri-
fied by flash column chromatography (hexane/EtOAc = 1/
6). The ee values of the alcohol products were determined
by HPLC on a Chiralcel OD-H column. The absolute con-
figuration of the major enantiomer was assigned as R by
the comparison of elution order of HPLC with the reported
value.
¨
¨
J. Top. Curr. Chem. 2000, 207, 1–67; (d) Faust, R. Angew.
Chem., Int. Ed. 2001, 40, 2251–2253.
3. (a) de Meijere, A. Angew. Chem. 1979, 11, 867–884; (b) de
Meijere, A.; Wessjohann, L. Synlett 1990, 20–32; (c)
Wiberg, K. B. Acc. Chem. Res. 1996, 29, 229–234; (d)
Suckling, C. J. Angew. Chem., Int. Ed. Engl. 1988, 27, 537–
552; (e) Reichelt, A.; Martin, S. F. Acc. Chem. Res. 2006, 39,
433–442.
4. (a) Naumann, K. Synthetic Pyrethroid Insecticides: Chemis-
try and Patents. In Chemistry of Plant Protection, Synthetic
Pyrethroid Insecticides; Haug, G., Hoffmann, H., Eds.;
Springer: Heidelberg, 1990; Vol. 5, p 63; (b) Arlt, D.;
Jautelat, M.; Lantzsch, R. Angew. Chem., Int. Ed. Engl.
1981, 20, 703–722.
5. For some reviews, see: (a) Davies, H. M. L. Tetrahedron 1993,
49, 5203–5223; (b) Mann, J. Tetrahedron 1986, 42, 4611–4659;
(c) Piers, E. In Comprehensive Organic Synthesis; Trost, B.
M., Ed.; Pergamon Press: Oxford, 1991; Vol. 5, p 971; (d)
Hudlicky, T.; Fan, R.; Reed, J.; Gadamasetti, K. G. Org.
React. 1992, 41, 1–133; (e) Hudlicky, T.; Reed, J. W. In
Comprehensive Organic Synthesis; Trost, B. M., Fleming, I.,
Eds.; Pergamon Press: Oxford, 1991; Vol. 5, p 899; (f)
Goldschmidt, Z.; Crammer, B. Chem. Soc. Rev. 1988, 17,
229–267; (g) Hudlicky, T.; Kutchan, T. M.; Naqvi, S. M. Org.
React. 1985, 33, 247–335; (h) Nonhebel, D. C. Chem. Soc.
Rev. 1993, 347–359; (i) Reissig, H.-U. Top. Curr. Chem. 1988,
4.7.1. (R)-Phenyl(p-tolyl)methanol.12 Chiralcel OD-H,
UV 225 nm, hexane/2-propanol = 90/10, 1 mL/ min.
tR = 9.5 min (S), 10.4 min (R); 87% ee.
4.7.2.
(R)-(2-Bromophenyl)(phenyl)methanol. Chiralcel
OD-H, UV 225 nm, hexane/2-propanol = 90/10, 1 mL/
min. tR = 9.6 min (R), 14.0 min (S); 79% ee.
4.7.3.
(R)-(3-Bromophenyl)(phenyl)methanol. Chiralcel
OD-H, UV 225 nm, hexane/2-propanol = 90/10,
1
mL/ min. tR = 11.7 min (S), 13.2 min (R); 83% ee.
4.7.4.
(R)-(2-Chlorophenyl)(phenyl)methanol. Chiralcel
144, 73–135; (j) Salaun, J. R. Y. Top. Curr. Chem. 1988, 144,
¨
OD-H, UV 225 nm, hexane/2-propanol = 90/10,
mL/ min. tR = 9.1 min (R), 11.5 min (S); 72% ee.
1
1–71; (k) Wong, H. N. C.; Hon, M.-Y.; Tse, C.-W.; Yip,
Y.-C.; Tanko, J.; Hudlicky, T. Chem. Rev. 1989, 89, 165–198;
(l) Rinderhagen, H.; Waske, P. A.; Mattay, J. Tetrahedron
2006, 62, 6589–6593.
4.7.5. (R)-(2-Methoxyphenyl)(phenyl)methanol. Chiralcel
OD-H, UV 225 nm, hexane/2-propanol = 98/2,
1
6. For recent, reviews see: (a) Reissig, H.-U. In Stereoselective
Synthesis of Organic Compounds; Methods of Organic Chem-
istry (Houben-Weyl); Helmchen, G., Hoffmann, R. W.,
Mulzer, J., Schaumann, E., Eds.; Thieme: Stuttgart, 1995; p
3179; (b) Doyle, M. P. In Catalytic Asymmetric Synthesis;
Ojima, I., Ed.; VCH: Weinheim, 1993; p 63; (c) Koert, U.
Nachr. Chem., Tech. Lab. 1995, 43, 435–436; (d) Charette, A.
B.; Marcoux, J.-F. Synlett 1995, 1197–1207; (e) Reissig, H.-U.
Angew. Chem., Int. Ed. 1996, 35, 971–973; (f) Aratani, T. Pure
Appl. Chem. 1985, 57, 1839–1844; (g) Salaun, J. Chem. Rev.
1989, 89, 1247–1270; (h) Lautens, M.; Klute, W.; Tam, W.
Chem. Rev. 1996, 96, 49–92; (i) Singh, V. K.; DattaGupta, A.;
Sekar, G. Synthesis 1997, 137–149; (j) Doyle, M. P.; Proto-
popova, M. N. Tetrahedron 1998, 54, 7919–7946; (k) Hartley,
R. C.; Caldwell, S. T. J. Chem. Soc., Perkin Trans. 1 2000,
477–501; (l) Donaldson, W. A. Tetrahedron 2001, 57, 8589–
8629; (m) Lebel, H.; Marcoux, J.-F.; Molinaro, C.; Charette,
A. B. Chem. Rev. 2003, 103, 977–1050; (n) Yu, M.;
Pagenkopf, B. L. Tetrahedron 2005, 61, 321–347; (o) Szymo-
niak, J.; Bertus, P. In Topics in Organometallic Chemistry;
Springer: Heidelberg, 2005; Vol. 10, p 107; (p) Bruneau, C.
Angew. Chem., Int. Ed. 2005, 44, 2328–2334; (q) Macaev, F.
Z.; Malkov, A. V. Tetrahedron 2006, 62, 9–29; (r) Yoshida,
J.-i. Synlett 2006, 515–526.
mL/ min. tR = 47.6 min (S), 56.9 min (R); 89% ee.
4.7.6. (R)-(Naphthalen-1-yl)(phenyl)methanol. Chiralcel
OD-H, UV 225 nm, hexane/2-propanol = 70/30,
mL/ min. tR = 7.2 min (S), 14.8 min (R); 88% ee.
1
4.7.7. (R)-(Naphthalen-2-yl)(phenyl)methanol. Chiralcel
OD-H, UV 225 nm, hexane/2-propanol = 90/10,
mL/ min. tR = 16.7 min (S), 20.2 min (R); 72% ee.
1
4.7.8. E-(R)-1,3-Diphenylprop-2-en-1-ol. Chiralcel OD-H,
UV 225 nm, hexane/2-propanol = 90/10,
mL/ min. tR = 17.4 min (R), 22.6 min (S); 72% ee.
1
Acknowledgment
Financial support from the National Natural Science
Foundation of China (Grant No. 20472111) is gratefully
acknowledged.
7. (a) Aviron-Violet, P.; Colleuille, Y.; Varagnat, J. J. Mol.
Catal. 1979, 5, 41–50; (b) Okada, Y.; Minami, T.; Yama-
moto, T.; Ichikawa, J. Chem. Lett. 1992, 547–550; (c)
Molander, G. A.; Burke, J. P.; Carroll, P. J. J. Org. Chem.
2004, 69, 8062–8069; For the chiral ligand including achiral
cyclopropane moiety, please see: (d) Sibi, M. P.; Ji, J. J. Org.
Chem. 1997, 62, 3800–3801; (e) Sibi, M. P.; Chen, J. J. Am.
Chem. Soc. 2001, 123, 9472–9473; (f) Sibi, M. P.; Ma, Z.;
Jasperse, C. P. J. Am. Chem. Soc. 2004, 126, 718–719.
8. Zhong, J. C.; Wang, M. A.; Guo, H. C.; Yin, M. M.; Bian, Q.
H.; Wang, M. Synlett 2006, 1667–1670.
References
1. For a general review on cyclopropanes, see: (a) Patai, S.;
Rappoport, Z. The Chemistry of the Cyclopropyl Group;
Wiley & Sons: New York, 1987, 1987; (b) Small Ring
Compounds in Organic Synthsis VI; de Meijere, A., Ed.;
Springer: Berlin, Germany, 2000; Vol. 207, (c) Houblen-Weyl
Methods of Organic Chemistry; Thieme: Stuttgart, 1997; Vol.
E 17c.

J. Zhong et al. / Tetrahedron: Asymmetry 18 (2007) 734–741
741
9. For recent reviews about the organozinc addition to alde-
hydes, please see: (a) Pu, L.; Yu, H.-B. Chem. Rev. 2001, 101,
757–824; (b) Pu, L. Tetrahedron 2003, 59, 9873–9886; (c) Soai,
K.; Nlwa, S. Chem. Rev. 1992, 92, 833–856; (d) Noyori, R.;
Kitamura, M. Angew. Chem., Int. Ed. Engl. 1991, 30, 49–69;
(e) Noyori, R. Asymmetric Catalysis in Organic Synthesis;
Wiley: New York, 1994, Chapter 5; (f) Bra¨se, S.; Dahmen, S.;
Ho¨fener, S.; Lauterwasser, F.; Kreis, M.; Ziegert, R. E.
Synlett 2004, 2647–2669; (g) Yus, M.; Ramon, D. J. Pure
Appl. Chem. 2005, 77, 2111–2119; For the chiral 1,4-amino
2447; (k) Bolm, C.; Rudolph, J. J. Am. Chem. Soc. 2002, 124,
14850–14851; (l) Rudolph, J.; Schmidt, F.; Bolm, C. Adv.
Synth. Catal. 2004, 346, 867–872; (m) Rudolph, J.; Her-
manns, N.; Bolm, C. J. Org. Chem. 2004, 69, 3997–4000; (n)
Ozcubukcu, S.; Schmidt, F.; Bolm, C. Org. Lett. 2005, 7,
1407–1409; (o) Tomita, D.; Wada, R.; Kanai, M.; Shibasaki,
M. J. Am. Chem. Soc. 2005, 127, 4138–4139; (p) Fontes, M.;
`
`
Verdaguer, X.; Sola, L.; Pericas, M. A.; Riera, A. J. Org.
Chem. 2004, 69, 2532–2543; (q) Ji, J.-X.; Wu, J.; Au-Yeung,
T. T.-L.; Yip, C.-W.; Haynes, R. K.; Chan, A. S. C. J. Org.
Chem. 2005, 70, 1093–1095; For recent reviews, see: (r) Bolm,
alcohol ligand, please see: (h) Knollmuller, M.; Ferencic, M.;
¨
Ga¨rtner, P. Tetrahedron: Asymmetry 1999, 10, 3969–3975; (i)
Faux, N.; Liu, X.; Razafimahefa, D.; Picart-Goetgheluck, S.
Tetrahedron: Asymmetry 2005, 16, 1189–1197; (j) Tanyeli, C.;
C.; Hilderbrand, J. P.; Muniz, K.; Hermanns, N. Angew.
Chem., Int. Ed. 2001, 40, 3284–3308; (s) Dimitrov, V.;
Kostova, K. Lett. Org. Chem. 2006, 3, 176–182.
˜
Sunbul, M. Tetrahedron: Asymmetry 2005, 16, 2039–
2043.
11. (a) Richmond, M. L.; Seto, C. T. J. Org. Chem. 2003, 68, 7505–
7508; (b) Nakamura, Y.; Takeuchi, S.; Okumura, K.; Ohgo, Y.
Tetrahedron 2001, 57, 5565–5571; (c) Vyskocil, S.; Jaracz, S.;
Smrcina, M.; Sticha, M.; Hanus, V.; Polasek, M.; Kocovsky,
P. J. Org. Chem. 1998, 63, 7727–7737; (d) Keinan, E.; Hafeli,
E. K.; Seth, K. K.; Lamed, R. J. Am. Chem. Soc. 1986, 108,
162–169; (e) Paquette, L. A.; Zhou, R. J. Org. Chem. 1999, 64,
7929–7934; (f) Soai, K.; Yokoyama, S.; Hayasaka, T. J. Org.
Chem. 1991, 56, 4264–4268; (g) Vastila, P.; Pastor, I. M.;
Adolfsson, H. J. Org. Chem. 2003, 70, 2921–2929.
12. (a) Ji, J.-X.; Wu, J.; Au-Yeung, T. T.-L.; Yip, C.-W.; Haynes,
R. K.; Chan Albert, S. C. J. Org. Chem. 2005, 70, 1093–1095;
(b) Wu, P.-Y.; Wu, H.-L.; Uang, B.-J. J. Org. Chem. 2005, 71,
833–835; (c) Wu, X.; Liu, X.; Zhao, G. Tetrahedron:
Asymmetry 2005, 16, 2299–2305; (d) Bolm, C.; Rudolph, J.
J. Am. Chem. Soc. 2002, 124, 14850–14851.
¨
¨
10. For recent examples, see: (a) Dosa, P. I.; Ruble, J. C.; Fu, G.
C. J. Org. Chem. 1997, 62, 444–445; (b) Huang, W.-S.; Pu, L.
J. Org. Chem. 1999, 64, 4222–4223; (c) Huang, W.-S.; Hu,
Q.-S.; Pu, L. J. Org. Chem. 1999, 64, 7940–7956; (d) Ko,
D.-H.; Kim, K. H.; Ha, D.-C. Org. Lett. 2002, 4, 3759–3762;
(e) Bolm, C.; Hermanns, N.; Hildebrand, J. P.; Muniz, K.
˜
Angew. Chem., Int. Ed. 2000, 39, 3465–3467; (f) Bolm, C.;
Kesselgruber, M.; Hermanns, N.; Hilderbrand, J. P. Angew.
Chem., Int. Ed. 2001, 40, 1488–1490; (g) Wu, P.-Y.; Wu,
H.-L.; Uang, B.-J. J. Org. Chem. 2006, 71, 833–835; (h) Ito,
K.; Tomitaa, Y.; Katsuki, T. Tetrahedron Lett. 2005, 46,
6083–6086; (i) Wu, X.; Liu, X.; Zhao, G. Tetrahedron:
Asymmetry 2005, 16, 2299–2305; (j) Chai, Z.; Liu, X.-Y.; Wu,
X.-Y.; Zhao, G. Tetrahedron: Asymmetry 2006, 17, 2442–