Asymmetric synthesis of 3-amino-2-hydroxyalkanoates by Mannich reaction of menthyl acetate with imines and subsequent oxidation

Article abstract of DOI:10.1016/j.tet.2007.05.031

Lithium amide-assisted Mannich-type reaction of menthyl acetate-derived lithium enolate with PMP-arylaldimines and subsequent in situ oxidation with oxaziridine gave syn-3-amino-3-aryl-2-hydroxypropanoates with high syn-selectivity and diastereoselectivit

Full text of DOI:10.1016/j.tet.2007.05.031

Tetrahedron 63 (2007) 8514–8520
Asymmetric synthesis of 3-amino-2-hydroxyalkanoates
by Mannich reaction of menthyl acetate with
imines and subsequent oxidation
*
Seiji Hata and Kiyoshi Tomioka
Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
Received 16 March 2007; revised 4 May 2007; accepted 8 May 2007
Available online 13 May 2007
Abstract—Lithium amide-assisted Mannich-type reaction of menthyl acetate-derived lithium enolate with PMP-arylaldimines and subse-
quent in situ oxidation with oxaziridine gave syn-3-amino-3-aryl-2-hydroxypropanoates with high syn-selectivity and diastereoselectivity
(with respect to menthyl moiety) in a one-pot procedure. Propargyl aldehyde-derived imines were also stereoselectively converted to the
Mannich-oxidation products by a stepwise procedure.
Ó 2007 Published by Elsevier Ltd.
OR2
H
1. Introduction
R1
O
NH
O
OH
O
Asymmetric Mannich reaction of lithium enolates with
imines is a fundamental asymmetric carbon–carbon bond
forming reaction, giving 3-aminoalkanoates. We have
been involved in this field and have developed highly effi-
cient asymmetric Mannich reaction of lithium enolate of
menthyl acetate with anisidine imines of arylaldehydes.1
The key of this successful procedure is the concomitant
use of lithium amide as an assisting agent for the Mannich
reaction, giving lithiated 3-aminoenolate as a reactive prod-
uct. The purpose of this article is to demonstrate the utility of
this product enolate in a further transformation such as oxi-
dation. Another purpose of this article is to report further
application of lithium menthyl acetate enolate in the reaction
with anisidine imines of propargyl aldehydes.
13
Ph
O
OH
HO
BzO
AcO
1 Paclitaxel R1 = Bz, R2 = Ac
2 Docetaxel R1 = Boc, R2 = H
Figure 1. Taxane anticancer drugs.
imine has been one of the representatives for the highly effi-
cient asymmetric synthesis, while the reaction of easily
available menthyl ester has proven not to be selective.4n
The one-pot reaction, asymmetric conjugate addition of
a chiral lithium amide to cinnamate, and in situ oxidation
of an enolate with an oxaziridine, provided a nice way,
unfortunately, to an undesired anti-amino alcohol.4u The
Mannich-type reaction of a lithium enolate of glycolate
with a chiral sulfinylimine would have been a really efficient
way if the chiral auxiliary was recyclable.4a
Anticancer taxoids, paclitaxel 1, and docetaxel 2,2 have
some barriers of which the major one is resource limitation.
Semi-synthesis thereof from commercially available 10-
deacetylbaccatin III and a C13 side chain has proven to be
the solution (Fig. 1).3 This situation has brought the neces-
sity of the efficient synthesis of enantiopure side chain units,
syn-3-amino-3-aryl-2-hydroxypropanoates. Over the last
two decades, therefore, the asymmetric synthesis of the
side chain units has attracted much attention from academic
as well as industrial communities.4 For examples, three
types of direct synthesis have been reported for chiral syn-
aminohydroxyphenylpropanoates. The Mannich-type addi-
tion of chiral trans-2-phenylcyclohexyl glycolate to an
We have been involved in the asymmetric reaction of lithium
ester enolates with aldimines, giving the corresponding
b-lactams or 3-aminoalkanoates with high enantioselectiv-
ity.1,5 The characteristic and appealing point of our reaction
exists in the aiding use of lithium amide for the reactivity en-
hancement of lithium enolate 3, in which dianion 5, gener-
ated by further lithiation of an adduct ester with lithium
amide, is the product (Scheme 1). Since the dianion 5 may
be reactive enough to give an oxidation product at the a-
position of an ester, we extended our study to the asymmetric
* Corresponding author. E-mail: tomioka@pharm.kyoto-u.ac.jp
0040–4020/$ - see front matter Ó 2007 Published by Elsevier Ltd.
doi:10.1016/j.tet.2007.05.031

S. Hata, K. Tomioka / Tetrahedron 63 (2007) 8514–8520
8515
synthesis of the C13 side chain unit 6 (R4¼OH). We describe
herein the diastereoselective (with respect to menthyl
moiety) and syn-selective synthesis of syn-3-amino-3-aryl-
2-hydroxypropanoates 6 by the one-pot, consecutive Man-
nich-oxidation reaction of lithium enolate of menthyl acetate
with arylaldimines. Propargyl aldehyde-derived imines were
also stereoselectively converted to the Mannich-oxidation
products by a stepwise procedure.
O
N
N
N
O
Ph
SO2Ph
S
S
O
O2
O2
13
14
15
converting it to the established compound 19 as shown in
Scheme 2. The ratio was determined by 1H NMR,
0.40 ppm (syn) and 0.68 ppm (anti) for one methyl of the
isopropyl group appeared as doublet. It is also interesting
to describe that the diastereomer ascribable to L-menthyl
group was not observed. Fortunately, recrystallization from
a 1:1 mixture of methanol and hexane gave pure anti-12 as
colorless needles.8 Treatment with (+)-camphorylsulfonyl-
oxaziridine 14 at ꢀ78 ꢁC for 0.5 h gave a syn-major 81:19
mixture of 11 and 12 (entry 2). Recrystallization from meth-
anol gave syn-11 as colorless needles. syn-Stereochemistry
was determined by converting syn-11 to the b-lactam 19 of
the established stereochemistry (vide infra). Selectivity was
more improved by the use of (ꢀ)-15 at ꢀ78 ꢁC for 0.5 h to
give a 96:4 mixture of syn-11 and anti-12 (entry 3). Com-
plexing ligand for lithium affected the level of diastereo-
selectivity. Although addition of HMPA (PO(NMe2)3)9
gave a similar level of 92:8 syn/anti-selectivity and 4.5 equiv
of DABCO (1,4-diazabicyclo[2.2.2]octane) exerted benefi-
cial effect to give a 98.5:1.5 mixture of 11 and 12 in 66%
yield (entries 4 and 5). Single recrystallization from metha-
nol gave pure syn-11 in 73% recovery.
Li
O
PMP
O
N
R3
+ LDA +
Ar
4
3
H+
or
[O]
PMP
Ar
NH
O
PMP
Ar
Li
Li
O
N
O
R3
R3
O
R4
6 R4 = H or OH
5
Scheme 1. Lithium amide-assisted Mannich-type reaction and subsequent
oxidation.
2. Results and discussion
2.1. One-pot Mannich-oxidation tandem reaction
Successive treatment of L-menthyl acetate 7 with 2.25 equiv
of LDA (iPr2NLi) in THF at ꢀ30 ꢁC for 1 h to generate lith-
ium enolate 8, and benzaldehyde PMP (p-methoxyphenyl)
imine 4a at ꢀ30 ꢁC for 4 h should produce dianion 9 that
is protonated with water to give 10 (R5¼R6¼H) with 96:4
dr in 76% yield as has been previously reported.1b In the
present study, dianion 9, generated in situ, was treated
with some oxidizing reagents. Treatment with MoOPD6
(MoO5/Py/DMPU (N,N0-dimethylpropyleneurea)) gave a
complex mixture containing only trace amount of 11 and
12. Promising result was obtained by oxidation with 2 equiv
of racemic-oxaziridine 137 at ꢀ78 ꢁC for 0.5 h to give an
anti-major 24:76 mixture of syn-11 and anti-12 in 58% yield
(Table 1, entry 1). The syn structure of 11 was determined by
PMP
PMP
Ph
O
NH
O
N
MeMgBr
THF
99%
Ph
O
OR7
OTBS
17
TBSCl
imidazole
quant.
syn-11: R7 = H
16: R7 = TBS
O
O
CAN
TBAF
THF
81% (2steps)
HN
Ph
HN
aq. MeCN
OH
Ph
OTBS
Table 1. One-pot Mannich-oxidation of L-menthyl acetate 7 with phenyl-
imine 4a
18
19
Scheme 2. Conversion of syn-11 to cis-b-lactam 19.
LDA
PMP
OLi
O
2.25 eq
N
+ LDA +
Conversion of syn-11 into b-lactam 19,10 an established
precursor for C13 side chain unit of taxol-derived anticancer
drugs, was performed in four steps. The OH group of 11 was
quantitatively converted to TBS ether 16 with TBSCl and
imidazole in DMF at rt for 12 h. b-Lactamization with meth-
ylmagnesium bromide in THF at ꢀ10 ꢁC for 1 h gave 17 in
99% yield. PMP group of 17 was removed by CAN oxida-
tion in acetonitrile at 0 ꢁC for 1 h and subsequent TBAF
treatment of 18 in THF at 0 ꢁC for 15 min gave b-lactam
194b,11 in 81% yield over two steps, thus established the
stereochemistry of 11.
THF
–78 °C
1 h
O
O
Ph
8
4a
7
PMP
[O]
Li
O
Li
PMP
Ph
NH
O
N
O
additive
–30 °C
4 h
Ph
O
–78 °C
0.5 h
R6 R5
10 R5 = R6 =H
9
syn-11 R5 =OH, R6 = H
anti-12 R5 = H, R6 = OH
Entry
[O]
Additive
Yield/%
syn-11/anti-12
The one-pot Mannich-oxidation protocol was applied to
imines 4b–e as shown in Table 2. Arylimines 4 bearing
electron donating 4-methoxyphenyl, electron withdrawing
4-chloro- and 4-trifluoromethyl-phenyl, and naphthyl
groups were successfully converted to the corresponding
1
2
3
4
5
13
14
15
15
15
None
None
None
HMPA
DABCO
58
49
66
63
66
24:76
81:19
96:4
92:8
98.5:1.5

8516
S. Hata, K. Tomioka / Tetrahedron 63 (2007) 8514–8520
Table 2. One-pot Mannich-oxidation of L-menthyl acetate 7 with aryl-
imines 4
observed (entry 8). These solvent effects on dr and yield
suggested the beneficial use of a coordinating ligand for
lithium. Thus we turned our attention to ligand activation
of lithium enolate 8. We examined the reaction of 21a
with 8, prepared from 7 and a slightly excess of LDA, in
the presence of HMPA, DMPU, TMEDA (N,N,N0,N0-tetra-
methylethylenediamine), and DABCO as a ligand for lith-
ium. Although HMPA caused lower yield of 31% (entry
9), other activators worked well to give 22a in 89–96% yield
(entries 10–12). Especially, the reaction of 8 in the presence
of DABCO in THF at ꢀ78 ꢁC for 0.5 h gave 22a in satisfac-
tory 96% yield and 95.5:4.5 dr (entry 12). Under the same
conditions, the reaction of 21b (R8¼TMS) gave 22b in
76% yield and 91.5:8.5 dr (entry 13). Recrystallization
gave nearly diastereomerically pure 22a and 22b.
PMP
N
N
S
15
O
LDA
O2
PMP
Ar
Ar
NH
O
O
2.25 eq
4
DABCO
–78 °C
time
THF
–78 °C
1 h
–30 °C
4 h
O
O
OH
20
7
Entry
4
Ar
Temp/ꢁC Time/h Yield% syn/anti
1
2
3
4
4b 4-MeOC6H4 ꢀ30
4
2
3
3
65
56
43
50
96:4
96:4
90:10
98:2
4c 4-ClC6H4
4d 4-CF3C6H4
4e 2-Naph
ꢀ30
ꢀ40
ꢀ40
Mannich addition product 22a was then converted to a di-
anion by treating with 3 equiv of LDA for 1 h, and then
oxidized with 15 in the presence of 3 equiv of DABCO at
ꢀ78 ꢁC for 0.5 h to give 23a with 94:6 syn/anti ratio in
57% yield. Recrystallization gave pure 23a. Similarly 22b
was oxidized to 23b with 97:3 syn/anti ratio in 68% yield.
Recrystallization gave pure 23b (Scheme 3).
syn-3-amino-2-hydroxypropanoates 20 with 90:10 to 98:2
syn/anti-selectivity in 43–65% yield. Diastereomers ascrib-
able to L-menthyl moiety were not observed.
2.2. Mannich reaction with propargyl aldehyde-derived
imine and subsequent oxidation
The LDA or LICA (cHexiPrNLi)-assisted Mannich reaction
of lithium enolate of menthyl acetate 7 with a propargyl
aldehyde-derived imine 21a gave the corresponding
Mannich product 22a in high diastereoselectivity of 98:2
or 98.5:1.5, respectively (Table 3, entries 1 and 2). Unfortu-
nately chemical yields were not satisfactory as low as 35%
and 37%. More bulky lithium amides, TMSTrNLi and
t-BuTrNLi, improved the chemical yield to 60% and 70%,
while diastereoselectivity dropped to 81.5:18.5 and
91.5:8.5 (entries 3 and 4).
i. LDA
ii. DABCO
PMP
N
PMP
NH
O
NH
O
S
O
15
O2
O
O
–78 °C
R
R
OH
22a R = Ph
22b R = TMS
23a R = Ph, 94:6 57%
23b R = TMS, 97:3 68%
Scheme 3. syn-Selective oxidation of 22.
In the absence of any additive such as lithium amide, 22a
with 84.5:15.5 dr was obtained in 63% yield (entry 5). Dime-
thoxyethane (DME) as a solvent gave higher dr of 93:7 with
86% yield, while addition of DABCO was not beneficial
(entries 6 and 7). In toluene, no diastereoselectivity was
3. Conclusion
A one-pot Mannich-oxidation sequential protocol for the
asymmetric synthesis of C13 side chain unit for taxane
Table 3. Mannich-type reaction with propargyl aldehyde-derived imines 21
PMP
PMP
additive
2.25 eq
N
NH
O
OLi
lithium
amide
1.25 eq
+
+
R8
O
–78 °C
O
R8
21a: R8 = Ph
22a: R8 = Ph
8
21b: R8 = TMS
22b: R8 = TMS
Entry
Solvent
Lithiuim amide
LDA (iPr2NLi)
Additive
Imine
Temp/ꢁC
Time/h
Yield/%
dr
98:2
98.5:1.5
81.5:18.5
91.5:8.5
84.5:15.5
93:7
1
2
3
4
5
6
7
8
THF
THF
THF
THF
THF
DME
DME
Toluene
THF
THF
THF
THF
THF
None
None
None
None
None
None
DABCO
None
HMPA
DMPU
TMEDA
DABCO
DABCO
21a
21a
21a
21a
21a
21a
21a
21a
21a
21a
21a
21a
21b
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ20
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ78
2
2
2
35
37
60
70
63
86
80
56
31
95
89
96
76
LICA (cHexiPrNLi)
TMSTrNLi
t-BuTrNLi
None
0.5
2.5
0.5
0.5
4.5
0.5
1
1
0.5
1
None
None
None
None
None
None
None
None
87.5:12.5
0
Nd
9
10
11
12
13
83:17
93.5:6.5
95.5:4.5
91.5:8.5

S. Hata, K. Tomioka / Tetrahedron 63 (2007) 8514–8520
8517
anticancer agents was developed. A two-step sequence was
effective for propargyl aldehyde-derived imines to give
syn-3-amino-2-hydroxyalkanoates with high syn/anti-
selectivity. Since menthol belongs to a class of cost-effective
chiral sources and is readily available, the use of menthyl
acetate as a chiral acetate has a broad application. It is also
remarkable to note that the lithium amide not only assists
the activation of lithium ester enolates but also plays its
original lithiation role of forming lithium enolate, which is
a reactive nucleophile.
4.1.2. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
(2S,3S)-2-hydroxy-3-(4-methoxyphenylamino)-3-phe-
nylpropanoate anti-12 (Table 1, entry 1). Recrystallization
of 24:76 syn/anti mixture (248 mg) from methanol/hexane
(1:1 mL) gave pure anti-12a (65 mg) as colorless needles
of mp 121–121.5 ꢁC and [a]2D5 ꢀ18.5 (c 1.05, benzene). 1H
NMR: 0.68 and 0.84 (each 3H, d, J¼7.0 Hz), 0.89 (1H,
m), 0.91 (3H, d, J¼6.4 Hz), 0.96–1.04 (2H, m), 1.36–1.45
(2H, m), 1.64–1.70 (3H, m), 1.83 (1H, m), 2.93 (1H, d,
J¼7.4 Hz), 3.69 (3H, s), 4.63 (2H, br s and dd are overlap-
ped, J¼3.4, 7.4 Hz), 4.70 (1H, ddd, J¼4.3, 11.0, 11.0 Hz),
4.77 (1H, d, J¼3.4 Hz), 6.58 (2H, d, J¼9.2 Hz), 6.69 (2H,
d, J¼9.2 Hz), 7.24–7.29 (3H, m), 7.32 (2H, d, J¼7.4 Hz).
13C NMR: 15.8 (CH3), 20.6 (CH3), 21.9 (CH3), 23.0
(CH2), 25.6 (CH2), 31.3 (CH), 34.1 (CH), 40.8 (CH), 46.9
(CH2), 55.7 (CH3), 61.1 (CH), 75.1 (CH), 75.8 (CH), 114.8
(CH), 114.9 (CH), 127.6 (CH), 128.1 (CH), 128.3 (CH),
139.1 (C), 140.6 (C), 152.2 (C), 171.3 (C). IR (KBr): 3500,
1728. EIMS m/z: 425 (M+). Anal. Calcd for C26H35NO4: C,
73.38; H, 8.29; N, 3.29. Found: C, 73.24; H, 8.17; N, 3.28.
4. Experimental
4.1. General
Melting points are uncorrected. Reactions were carried out
under Ar. Silica gel column chromatography was used for
1
purification. IR spectra were expressed in cmꢀ1. H and
13C NMR spectra were taken in CDCl3 at 500 and
125 MHz, respectively. Chemical shift values are expressed
in parts per million relative to internal TMS. Abbreviations
are as follows: s, singlet; d, doublet; t, triplet; q, quartet; m,
multiplet; br, broad.
4.1.3. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
(2R,3S)-2-tert-butyldimethylsiloxy-3-(4-methoxy-
phenylamino)-3-phenylpropanoate syn-16. A mixture of
imidazole (37 mg, 0.54 mmol), TBDMSCl (40 mg,
0.27 mmol), and syn-11 (23 mg) in 0.06 mL of DMF was
stirred for 12 h at rt. Then ether (10 mL) and water (2 mL)
were added. The organic layer was washed with water
(2 mLꢂ4) and dried over sodium sulfate and concentrated.
Column chromatography (hexane/ether¼9:1) gave syn-16
(30 mg, quant) as a colorless gum of [a]2D5 ꢀ19.8 (c 1.18,
4.1.1. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
(2R,3S)-2-hydroxy-3-(4-methoxyphenylamino)-3-phe-
nylpropanoate syn-11 (Table 1, entry 5). A solution of
L-menthyl acetate (396 mg, 2.0 mmol) in THF (3 mL) was
added dropwise over 5 min at ꢀ78 ꢁC to a solution of LDA
(4.5 mmol) in THF (3 mL) and the resulting mixture was
stirred at ꢀ78 ꢁC for 0.5 h. A solution of imine 4a
(211 mg, 1.0 mmol) in THF (3 mL) was added dropwise
over 10 min at ꢀ78 ꢁC and the mixture was stirred at ꢀ30 ꢁC
for 2 h. A solution of DABCO (505 mg, 4.5 mmol) in THF
(5 mL) was added at ꢀ78 ꢁC to the mixture and the mixture
was stirred for 0.5 h. Then, (ꢀ)-camphorylsulfonyloxazir-
idine 15 (688 mg, 3.0 mmol) in THF (3 mL) was added to
the mixture. The mixture was stirred for 0.5 h at ꢀ78 ꢁC
and then quenched with satd ammonium chloride (20 mL)
at ꢀ78 ꢁC. The whole was extracted with ethyl acetate
(30 mLꢂ3). Combined organic layers were washed with
brine (20 mL) and dried over sodium sulfate. Concentration
and column chromatography (hexane/Et2O¼4:1) gave a
98.5:1.5 mixture of 11 and 12 (280 mg, 66% yield) as color-
less needles. Ratio was determined from the integration
values of 0.40 ppm (syn) and 0.68 ppm (anti) by NMR.
Recrystallization from methanol gave syn-11 (205 mg) as
colorless needles of mp 149.5–150 ꢁC and [a]D25 ꢀ38.4 (c
0.58, CHCl3). 1H NMR: 0.40 and 0.57 (each 3H, d,
J¼7.0 Hz), 0.86 (1H, m), 0.92 (3H, d, J¼6.4 Hz), 0.97 (1H,
m), 1.05 (1H, m), 1.39 (1H, m), 1.50 (1H, m), 1.63–1.70
(3H, m), 2.03 (1H, m), 3.16 (1H, br s), 3.67 (3H, s), 4.46
(1H, d, J¼2.7 Hz), 4.81 (1H, ddd, J¼4.3, 10.4, 10.4 Hz),
4.86 (1H, br s), 6.44 and 6.66 (each 2H, d, J¼8.9 Hz), 7.24
(1H, m), 7.3 (2H, m), 7.38 (2H, d, J¼7.7 Hz). 13C NMR:
14.9 (CH3), 20.5 (CH3), 21.9 (CH3), 22.6 (CH2), 25.3 (CH2),
31.3 (CH), 34.0 (CH), 40.7 (CH), 47.0 (CH2), 55.6 (CH3),
58.8 (CH), 74.9 (CH), 76.6 (CH), 114.5 (CH), 115.3 (CH),
127.4 (CH), 127.9 (CH), 128.5 (CH), 139.4 (CH), 140.2
(C), 152.0 (C), 172.7 (C). IR (KBr): 3395, 2951, 1720.
EIMS m/z: 425 (M+). Anal. Calcd for C26H35NO4: C,
73.38; H, 8.29; N, 3.29. Found: C, 73.28; H, 8.46; N, 3.22.
1
CHCl3). H NMR: ꢀ0.40 (3H, s), ꢀ0.18 (3H, s), 0.39 and
0.59 (each 3H, d, J¼7.0 Hz), 0.74 (9H, s), 0.84 (1H, m),
0.89 (3H, d, J¼6.4 Hz), 0.94–1.02 (2H, m), 1.35 (1H, m),
1.46 (1H, m), 1.58–1.66 (3H, m), 1.92 (1H, m), 3.65 (3H,
s), 4.39 (1H, d, J¼2.5 Hz), 4.58 (1H, br s), 4.75 (1H, ddd,
J¼4.3, 11.0, 11.0 Hz), 4.81 (1H, br s), 6.39 (2H, d, J¼
8.9 Hz), 6.62 (2H, d, J¼8.9 Hz), 7.19 (2H, t, J¼7.2 Hz),
7.27 (2H, t, J¼7.2 Hz), 7.32 (2H, d, J¼7.2 Hz). 13C NMR:
ꢀ6.21 (CH3), ꢀ5.67 (CH3), 15.0 (CH3), 18.2 (C), 20.7
(CH3), 22.0 (CH3), 22.7 (CH2), 25.5 (CH3), 25.5 (CH2),
31.4 (CH), 34.2 (CH), 41.0 (CH), 47.1 (CH2), 55.8 (CH3),
60.4 (CH), 75.0 (CH), 77.1 (CH), 114.2 (CH), 114.7 (CH),
127.3 (CH), 127.4 (CH), 128.3 (CH), 140.0 (C), 140.7 (C),
151.7 (C), 171.2 (C). IR (KBr): 3422, 1747. EIMS m/z:
539 (M+). HRMS m/z: calcd for C32H49NO4Si: 539.3431.
Found: 539.3426.
4.1.4. (3R,4S)-3-tert-Butyldimethylsiloxy-1-(4-methoxy-
phenyl)-4-phenylazetidin-2-one cis-17. To a solution of
syn-16 (74 mg, 0.137 mmol) in 5 mL of THF was added
MeMgBr (0.5 M THF solution, 0.82 mL, 0.41 mmol) at
ꢀ78 ꢁC and the mixture was stirred for 1 h at ꢀ10 ꢁC and
quenched with satd ammonium chloride, and then extracted
with ethyl acetate (10 mLꢂ3). The combined organic layer
was washed with brine (20 mL) and dried over sodium sul-
fate, and then concentrated. Column chromatography (hex-
ane/Et2O¼9:1) gave cis-17 (54 mg, 99%) as colorless
needles of mp 139–140 ꢁC (hexane) and [a]2D5 ꢀ75.6 (c
1
0.75, CHCl3). H NMR: ꢀ0.15 (3H, s), 0.07 (3H, s), 0.64
(9H, s), 3.74 (3H, s), 5.11 (2H, m), 6.77–6.79 (2H, d, J¼
9.2 Hz), 7.28–7.33 (7H, m). 13C NMR: ꢀ5.39 (CH3),
ꢀ4.87 (CH3), 17.8 (C), 25.3 (CH3), 55.4 (CH3), 62.8 (CH),

8518
S. Hata, K. Tomioka / Tetrahedron 63 (2007) 8514–8520
77.6 (CH), 114.1 (CH), 118.9 (CH), 128.2 (CH), 128.2 (CH),
128.3 (CH), 131.0 (C), 134.1 (C), 156.2 (C), 165.5 (C).
EIMS m/z: 383 (M+). IR (KBr): 1720. Anal. Calcd for
C22H29NO3Si: C, 68.89; H, 7.62; N, 3.65. Found: C,
68.83; H, 7.60; N, 3.48.
benzene). The ratio was determined from the integration
values of 6.67 ppm (syn) and 6.48 ppm (anti). The spectral
data of major isomer: 1H NMR: 0.39 and 0.56 (each 3H, d,
J¼7.0 Hz), 0.83–1.08 (6H, m), 1.39 (1H, m), 1.49 (1H,
m), 1.62–1.68 (3H, m), 2.02 (1H, m), 3.22 (1H, dd, J¼
1.2 Hz, 2.8 Hz), 3.68 (3H, s), 4.41 (1H, m), 4.50 (1H, br
s), 4.78–4.82 (2H, m), 6.41 and 6.67 (each 2H, d, J¼
8.9 Hz), 7.30 and 7.33 (each 2H, d, J¼8.9 Hz). 13C NMR:
14.9 (CH3), 20.5 (CH3), 21.9 (CH3), 22.6 (CH2), 25.4
(CH2), 31.4 (CH), 34.0 (CH), 40.7 (CH), 47.0 (CH2), 55.7
(CH3), 58.3 (CH), 74.7 (CH), 76.9 (CH), 114.5 (CH), 114.7
(CH), 128.5 (CH), 128.8 (CH), 133.2 (C), 138.1 (C), 139.8
(C), 152.2 (C), 172.6 (C). IR (KBr): 3395, 1728. EIMS
m/z: 460 (M+). HRMS m/z: calcd for C26H34ClNO4:
459.2176. Found: 459.2171.
4.1.5. (3R,4S)-3-tert-Butyldimethylsiloxy-1-(4-methoxy-
phenyl)-4-phenylazetidin-2-one cis-18. To a solution of
cis-17 (30 mg, 0.078 mmol) in 3 mL of acetonitrile was
slowly added CAN (128 mg, 0.235 mmol) in water
(10 mL) at 0 ꢁC and the mixture was stirred for 1 h. The re-
action was quenched with water (10 mL) and extracted with
ethyl acetate (15 mLꢂ3). Combined organic layer was
washed with brine (20 mL) and dried over sodium sulfate,
and then concentrated to give a pale brown solid (27 mg).
Column chromatography (benzene/ethyl acetate¼30:1)
gave cis-18 (19.5 mg, 90%) as colorless fine needles of mp
4.1.9. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
(2R,3S)-2-hydroxy-3-(4-methoxyphenylamino)-3-[4-(tri-
fluoromethyl)phenyl]propanoate syn-20d (Table 2, entry
3). The 90:10 syn/anti ratio was determined from the integra-
tion values of 0.40 ppm (syn) and 0.49 ppm (anti). Recrys-
tallization (100 mg) from 1 mL of ethanol gave syn-20d
(75 mg) as colorless needles of mp 133.0–133.5 ꢁC and
1
108–110 ꢁC and [a]D25 +61.3 (c 0.62, CHCl3). H NMR:
ꢀ0.17 (3H, s), 0.04 (3H, s), 0.64 (9H, s), 4.80 (1H, d,
J¼4.8 Hz), 5.06 (1H, dd, J¼4.8, 2.3 Hz), 6.21 (1H, br s),
7.30–7.36 (5H, m). 13C NMR: ꢀ5.50 (CH3), ꢀ5.51 (CH3),
17.7 (C), 25.2 (CH3), 59.1 (CH), 79.6 (CH), 128.0 (CH),
128.0 (CH), 128.1 (CH), 136.3 (CH), 170.0 (C). EIMS
m/z: 277 (M+). IR (KBr): 3233, 1713. HRMS m/z: calcd
for C15H23NO2Si: 277.1498. Found: 277.1505.
1
[a]2D5 ꢀ36.1 (c 1.07, benzene). H NMR: 0.40 and 0.57
(each 3H, d, J¼7.0 Hz), 0.92 (3H, d, J¼6.4 Hz), 0.95–1.10
(3H, m), 1.39 (1H, m), 1.50 (1H, m), 1.62–1.69 (3H, m),
2.03 (1H, m), 3.33 (1H, br s), 3.68 (3H, s), 4.45 (1H, d,
J¼2.2 Hz), 4.54 (1H, br s), 4.82 (1H, ddd, J¼10.7, 10.7,
4.3 Hz), 4.91 (1H, br s), 6.42 and 6.67 (each 2H, d,
J¼8.9 Hz), 7.51 and 7.58 (each 2H, d, J¼7.9 Hz). 13C
NMR: 14.9 (CH3), 20.5 (CH3), 21.9 (CH3), 22.7 (CH2),
25.5 (CH2), 31.4 (CH), 34.0 (CH), 40.7 (CH), 47.1 (CH2),
55.7 (CH3), 58.5 (CH), 74.6 (CH), 77.2 (CH), 114.5 (CH),
4.1.6. (3R,4S)-3-Hydroxy-4-phenylazetidin-2-one 19. To
cis-18 (35 mg, 0.126 mmol) was added TBAF in THF
(1.0 M, 0.38 mL) and the mixture was stirred for 15 min at
0 ꢁC. Concentration and column chromatography (ethyl ace-
tate/benzene¼3:2) gave 19 (18.5 mg, 90%) as colorless fine
needles of mp 182–183 ꢁC (ethyl acetate) and [a]2D5 +178
1
(c 1.00, MeOH). H NMR (DMSO-d6): 4.69 (1H, d, J¼
1
4.6 Hz), 4.93 (1H, dd, J¼4.6, 7.0 Hz), 5.83 (1H, d, J¼
7.0 Hz), 7.23–7.37 (5H, m), 8.47 (1H, br s). Spectroscopic
data were identical with those reported for (3R,4S)-19.12
114.8 (CH), 124.2 (q, JC–F¼270.7 Hz, C), 125.6 (q,
2
3JC–F¼4.1 Hz, CH), 127.5 (CH), 129.8 (q, JC–F¼31.9 Hz,
C), 139.6 (C), 143.9 (C), 152.4 (C), 172.5 (C). IR (KBr):
3394, 1720. EIMS m/z: 493 (M+). Anal. Calcd for
C27H34F3NO3: C, 65.70; H, 6.94; N, 2.84. Found: C,
65.45; H, 7.04; N, 2.75.
4.1.7. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
(2R,3S)-2-hydroxy-3-(4-methoxyphenylamino)-3-(4-
methoxyphenyl)propanoate syn-20b (Table 2, entry 1).
The 96:4 syn/anti ratio was determined from the integration
values of 4.41 ppm (syn) and 4.45 ppm (anti). Recrystalliza-
tion (204 mg) from ethanol gave syn-20b (120 mg) as color-
less needles of mp 124–124.5 ꢁC and [a]D25 ꢀ27.8 (c 1.00,
benzene). 1H NMR: 0.40 and 0.58 (each 3H, d, J¼7.0 Hz),
0.82–1.09 (6H, m), 1.41 (1H, m), 1.50 (1H, m), 1.60–1.70
(3H, m), 2.01 (1H, m), 3.68 (3H, s), 3.77 (3H, s), 4.41 (1H,
d, J¼2.8 Hz), 4.77–4.83 (2H, m), 6.43 (2H, d, J¼8.9 Hz),
6.65 (2H, d, J¼8.9 Hz), 6.85 (2H, d, J¼8.6 Hz), 7.29 (2H,
d, J¼8.6 Hz). 13C NMR: 15.0 (CH3), 20.6 (CH3), 21.9
(CH3), 22.7 (CH2), 25.4 (CH2), 31.4 (CH), 34.1 (CH),
40.7 (CH), 47.1 (CH2), 55.2 (CH3), 55.7 (CH3), 58.3 (CH),
75.0 (CH), 77.1 (CH), 114.1 (CH), 114.7 (CH), 114.7
(CH), 128.1 (CH), 131.3 (C), 140.3 (C), 152.1 (C), 159.0
(C), 172.3 (C). IR (KBr): 3398, 1720. EIMS m/z: 455
(M+). Anal. Calcd for C27H37NO5: C, 71.18; H, 8.19; N,
3.07. Found: C, 71.15; H, 8.27; N, 3.04.
4.1.10. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
(2R,3S)-2-hydroxy-3-(4-methoxyphenylamino)-3-(naph-
thalen-2-yl)propanoate syn-20e (Table 2, entry 4). A 98:2
syn/anti ratio was determined from the integration values of
6.48 ppm (syn) and 6.56 ppm (anti). Recrystallization
(237 mg) from 10 mL of ethanol gave syn-20e (197 mg) as
colorless needles of mp 146–147 ꢁC and [a]D25 ꢀ28.8 (c
1.00, benzene). 1H NMR: 0.40 and 0.57 (each 3H, d,
J¼7.0 Hz), 0.86 (1H, m), 0.92 (3H, d, J¼6.7 Hz), 0.95–
1.10 (2H, m), 1.40 (1H, m), 1.50 (1H, m), 1.61–1.70 (3H,
m), 2.02 (1H, m), 3.21 (1H, d, J¼3.1 Hz), 3.65 (3H, s),
4.55 (1H, dd, J¼3.1, 2.7 Hz), 4.83 (1H, ddd, J¼4.3, 10.8,
10.8 Hz), 5.01 (1H, br s), 6.48 and 6.63 (2H, d, J¼8.9 Hz),
7.41–7.45 (2H, m), 7.52 (1H, dd, J¼8.6, 1.6 Hz), 7.78–
7.83 (4H, m). 13C NMR: 14.9 (CH3), 20.5 (CH3), 21.9
(CH3), 22.7 (CH2), 25.4 (CH2), 31.4 (CH), 34.0 (CH), 40.7
(CH), 47.1 (CH2), 55.7 (CH3), 59.2 (CH), 75.0 (CH), 76.8
(CH), 114.7 (CH), 114.8 (CH), 125.0 (CH), 125.8 (CH),
126.1 (CH), 126.2 (CH), 127.7 (CH), 128.0 (CH), 128.5
(CH), 133.0 (C), 133.4 (C), 137.1 (C), 140.2 (C), 152.2
(C), 172.7 (C). IR (KBr): 3395, 1720. EIMS m/z: 475
(M+). Anal. Calcd for C30H37NO4: C, 75.76; H, 7.84; N,
2.94. Found: C, 75.59; H, 7.79; N, 2.99.
4.1.8. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
(2R,3S)-2-hydroxy-3-(4-methoxyphenylamino)-3-(4-
chlorophenyl)propanoate syn-20c (Table 2, entry 2). Col-
umn chromatography (Hex/Et2O¼4:1) gave a 96:4 syn/anti
mixture as a pale brown gum of [a]2D5 ꢀ37.1 (c 1.26,

S. Hata, K. Tomioka / Tetrahedron 63 (2007) 8514–8520
8519
4.1.11. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl (3R)-
3-(4-methoxyphenylamino)-5-phenylpent-4-ynoate 22a
(Table 3, entry 12). A solution of L-menthyl acetate
(396 mg, 2.0 mmol) in THF (3 mL) was added dropwise
over 5 min at ꢀ78 ꢁC to a preformed solution of LDA
(2.25 mmol) in THF (3 mL). The mixture was stirred at
ꢀ78 ꢁC for 0.5 h. Then DABCO (505 mg, 4.5 mmol) in
THF (5 mL) was added at ꢀ78 ꢁC to the mixture. A solution
of imine 21a (235 mg, 1.0 mmol) in THF (3 mL) was added
dropwise over 10 min at ꢀ78 ꢁC to the mixture and the
mixture was stirred at ꢀ78 ꢁC for 0.5 h. The reaction was
quenched with satd ammonium chloride (20 mL) at
ꢀ78 ꢁC and extracted with AcOEt (30 mLꢂ3). Combined
organic layers were washed with brine (20 mL) and dried
over sodium sulfate, and then concentrated to give a pale yel-
low solid (655 mg). Column chromatography (hexane/
AcOEt¼15:1) gave 22a (420 mg, 96% yield) as pale yellow
solid. The ratio of two diastereomers was determined to be
95.5:4.5 from the integration values of 0.67 ppm (3R) and
0.71 ppm (3S). Recrystallization (330 mg) from 2 mL of 2-
propanol gave (3R)-22a as colorless needles of mp 106–
(1.5 mL, 0.45 mmol) was added THF solution of pure 22a
(65 mg, 0.15 mmol, 1.5 mL) at ꢀ78 ꢁC and the mixture
was stirred for 1 h at ꢀ30 ꢁC. A solution of DABCO
(50 mg, 0.45 mmol) in THF (1.5 mL) was added and the
mixture was stirred for 0.5 h at ꢀ78 ꢁC. Then, (ꢀ)-15
(52 mg, 0.23 mmol) in THF (1.5 mL) was added at
ꢀ78 ꢁC and the mixture was stirred for 0.5 h. The reaction
was quenched with satd ammonium chloride (5 mL) and ex-
tracted with ethyl acetate (10 mLꢂ3). Combined organic
layers were washed with brine (20 mL) and dried over so-
dium sulfate, and then concentrated to give a yellow solid
(101 mg). Column chromatography (hexane/AcOEt¼7:1)
gave 23a (38 mg, 57%) as a pale yellow solid. The 94:6 ratio
was determined from the integration values of 6.70 ppm
(syn) and 6.74 ppm (anti). Recrystallization (20 mg) from
1.5 mL of methanol gave pure 23a (15 mg) as colorless
fine needles of mp 164.0–165.0 ꢁC and [a]D25 +65.4 (c
1.00, benzene). 1H NMR: 0.44 and 0.64 (each 3H, d,
J¼7.0 Hz), 0.84–0.91 (4H, m), 0.95–1.08 (2H, m), 1.38
(1H, m), 1.49 (1H, m), 1.62–1.69 (2H, m), 1.75 (1H, m),
2.04 (1H, m), 3.43 (1H, br s), 3.75 (3H, s), 4.07 (1H, br s),
4.55 (1H, d, J¼2.5 Hz), 4.71 (1H, br s), 4.81 (1H, ddd,
J¼11.0, 11.0, 4.3 Hz), 6.70 and 6.80 (each 2H, d,
J¼9.2 Hz), 7.22–7.26 (3H, m), 7.34–7.36 (2H, m). 13C
NMR: 15.1 (CH3), 20.6 (CH3), 21.9 (CH3), 22.7 (CH2),
25.5 (CH2), 31.4 (CH), 34.0 (CH), 40.7 (CH), 47.0 (CH2),
49.5 (CH), 55.7 (CH3), 73.1 (CH), 77.1 (CH), 84.0 (C),
86.6 (C), 114.6 (CH), 116.3 (CH), 122.6 (CH), 128.1
(CH), 128.2 (CH), 131.9 (C), 139.7 (C), 153.3 (C), 171.8
(C). IR (KBr): 3425, 1728. EIMS m/z: 449 (M+). HRMS
m/z: calcd for C28H35NO4: 449.2566. Found: 449.2574.
1
107.0 ꢁC and [a]D25 +96.4 (c 1.00, CHCl3). H NMR: 0.67
and 0.79 (each 3H, d, J¼7.2 Hz), 0.84 (1H, m), 0.87 (3H,
d, J¼6.4 Hz), 0.96–1.08 (2H, m), 1.37 (1H, m), 1.47 (1H,
m), 1.64–1.69 (2H, m), 1.86 (1H, m), 2.03 (1H, m), 2.85
(1H, m), 3.03 (1H, m), 3.76 (3H, s), 4.00 (1H, br s), 4.66
(1H, m), 4.76 (1H, m), 6.77 and 6.81 (each 2H, d, J¼
7.9 Hz), 7.23–7.27 (3H, m), 7.33 (2H, d, J¼7.9 Hz). 13C
NMR: 16.0 (CH3), 20.6 (CH3), 21.9 (CH3), 23.2 (CH2),
26.0 (CH2), 31.3 (CH), 34.1 (CH), 41.0 (CH), 41.1 (CH),
44.7 (CH2), 47.0 (CH2), 55.7 (CH3), 74.8 (CH), 83.4 (C),
88.6 (C), 114.7 (CH), 116.7 (CH), 122.7 (CH), 128.2 (CH),
128.2 (CH), 131.8 (C), 140.2 (C), 153.4 (C), 170.2 (C). IR
(KBr): 3364, 1724. EIMS m/z: 433 (M+). HRMS m/z: calcd
for C28H35NO3: 433.2617. Found: 433.2621.
4.1.14. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl (3R)-
2-hydroxy-3-(4-methoxyphenylamino)-5-(trimethyl-
silyl)pent-4-ynoate 23b. Column chromatography (hexane/
Et2O¼6:1) gave 23b (68%) as a pale yellow solid. A 97:3
syn/anti ratio was determined from the integration values
of 0.64 ppm (syn) and 0.74 ppm (anti). Recrystallization
(90 mg) from a 1:1 mixture of 2-propanol and hexane
(0.5 mL) gave pure 23b (71 mg) as colorless fine needles
of mp 124.5–125.0 ꢁC and [a]2D5 +50.1 (c 0.69, benzene).
1H NMR: 0.10 (9H, s), 0.45 and 0.64 (each 3H, d,
J¼7.0 Hz), 0.84–0.91 (4H, m), 0.97–1.04 (2H, m), 1.34
(1H, m), 1.48 (1H, m), 1.61–1.70 (3H, m), 2.02 (1H, m),
3.36 (1H, br s), 3.75 (3H, s), 3.95 (1H, br s), 4.45 and 4.50
(each 1H, d, J¼2.4 Hz), 4.76 (1H, ddd, J¼11.0, 11.0,
4.3 Hz), 6.64 and 6.78 (each 2H, d, J¼8.9 Hz). 13C NMR:
ꢀ0.18 (CH3), 15.0 (CH3), 20.6 (CH3), 21.9 (CH3), 22.6
(CH2), 25.4 (CH2), 31.3 (CH), 34.0 (CH), 40.6 (CH), 47.0
(CH2), 49.4 (CH), 55.6 (CH3), 72.8 (CH), 76.9 (CH), 88.8
(C), 103.0 (C), 114.5 (CH), 116.3 (CH), 139.6 (C), 153.2
(C), 171.6 (C). IR (KBr): 3433, 1728. EIMS m/z: 445
(M+). Anal. Calcd for C25H39NO4Si: C, 67.37; H, 8.82; N,
3.14. Found: C, 67.31; H, 8.66; N, 3.09.
4.1.12. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl (3R)-
3-(4-methoxyphenylamino)-5-(trimethylsilyl)-pent-4-
ynoate 22b (Table 3, entry 13). Column chromatography
(hexane/Et2O¼9:1) gave 22b (76%) as pale yellow solid.
The diastereomer ratio was determined to be 91.5:8.5 from
the integration values of 0.70 ppm (3R) and 0.74 ppm (3S).
Recrystallization (300 mg) from 0.5 mL of hexane/2-propa-
nol (1:1) gave 97:3 mixture (175 mg) as pale brown fine
needles of mp 71.0–72.0 ꢁC and [a]2D5 +62.4 (c 0.99, benz-
1
ene). H NMR: 0.10 (9H, s), 0.71 and 0.83 (each 3H, d,
J¼7.0 Hz), 0.88–0.91 (4H, m), 0.98–1.06 (2H, m), 1.36
(1H, m), 1.48 (1H, m), 1.64–1.69 (2H, m), 1.84 (1H, m),
2.00 (1H, m), 2.74 (2H, d, J¼6.4 Hz), 3.76 (3H, s), 3.86
(1H, br s), 4.44 (1H, dd, J¼6.4, 6.4 Hz), 4.73 (1H, ddd,
J¼4.6, 11.0, 11.0 Hz), 6.71 and 6.80 (each 2H, d,
J¼8.8 Hz). 13C NMR: ꢀ0.26 (CH3), 16.0 (CH3), 20.6
(CH3), 21.9 (CH3), 23.2 (CH2), 26.0 (CH2), 31.3 (CH),
34.1 (CH), 40.6 (CH), 40.8 (CH), 44.7 (CH2), 46.8 (CH2),
55.5 (CH3), 74.6 (CH), 87.8 (C), 105.1 (C), 114.5 (CH),
116.6 (CH), 140.1 (C), 153.2 (C), 170.0 (C). IR (KBr):
3368, 1732. EIMS m/z: 429 (M+). Anal. Calcd for
C25H39NO3Si: C, 69.88; H, 9.15; N, 3.26. Found: C,
69.86; H, 9.00; N, 3.29.
Acknowledgements
This research was partially supported by the 21st Century
Center of Excellence Program ‘Knowledge Information In-
frastructure for Genome Science’ and a Grant-in-Aid for
Scientific Research on Priority Areas ‘Advanced Molecular
Transformations’ from the Ministry of Education, Culture,
4.1.13. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
(2R,3S)-3-(4-methoxyphenylamino)-2-hydroxy-5-phe-
nylpent-4-ynoate 23a. To a THF solution of 0.3 M LDA

8520
S. Hata, K. Tomioka / Tetrahedron 63 (2007) 8514–8520
Asymmetry 2000, 11, 4485; (l) Schade, W.; Reissig, H. U.
J. Prakt. Chem. 1999, 341, 685; (m) Cardillo, G.; Gentilucci,
L.; Tolomelli, A.; Tomasini, C. J. Org. Chem. 1998, 63,
2351; (n) Ojima, I.; Lin, S. J. Org. Chem. 1998, 63, 224; (o)
Li, G.; Chang, H.-T.; Sharpless, K. B. Angew. Chem., Int. Ed.
1996, 35, 451; (p) Wang, Zh.-M.; Kolb, H. C.; Sharpless,
K. B. J. Org. Chem. 1994, 59, 5104; (q) Crispino, G. A.;
Jeong, K. S.; Kolb, H. C.; Wang, Zh.; Xu, D. J. Org. Chem.
1993, 58, 3785; (r) Hattori, K.; Miyata, M.; Yamamoto, H.
J. Am. Chem. Soc. 1993, 115, 1151; (s) Deng, L.; Jacobsen,
E. N. J. Org. Chem. 1992, 57, 4320; (t) Denis, J. N.; Correa,
A.; Greene, A. E. J. Org. Chem. 1990, 55, 1957; (u)
Bunnage, M. E.; Davies, S. G.; Goodwin, C. J. J. Chem. Soc.,
Perkin Trans. 1 1994, 2385.
Sports, Science and Technology, Japan. We also express our
thanks to Dr. Tito Akindele for editing the manuscript.
References and notes
1. (a) Hata, S.; Iwasawa, T.; Iguchi, M.; Yamada, K.; Tomioka, K.
Synthesis 2004, 1471; (b) Hata, S.; Iguchi, M.; Iwasawa, T.;
Yamada, K.; Tomioka, K. Org. Lett. 2004, 6, 1721; (c)
Fujieda, H.; Kanai, M.; Kambara, T.; Iida, A.; Tomioka, K.
J. Am. Chem. Soc. 1997, 119, 2060; (d) Kambara, T.;
Tomioka, K. J. Org. Chem. 1999, 64, 9282; (e) Kambara, T.;
Hussein, M. A.; Fujieda, H.; Iida, A.; Tomioka, K.
Tetrahedron Lett. 1998, 39, 9055; (f) Hussein, M. A.; Iida,
A.; Tomioka, K. Tetrahedron 1999, 55, 11219; (g) Tomioka,
K.; Fujieda, H.; Hayashi, S.; Hussein, M. A.; Kambara, T.;
Nomura, Y.; Kanai, M.; Koga, K. Chem. Commun. 1999,
715; (h) Kambara, T.; Tomioka, K. Chem. Pharm. Bull. 1999,
47, 720.
2. (a) Cragg, G. M.; Newman, D. J. J. Nat. Prod. 2004, 67, 232; (b)
Ojima, I.; Lin, S.; Wang, T. Curr. Med. Chem. 1999, 6, 927.
3. (a) Hayashi, Y.; Kiso, Y. J. Synth. Org. Chem. Jpn. 2005, 63,
640; (b) Gennari, C.; Vulpetti, A.; Donghi, M.; Mongelli, N.;
Vanotti, E. Angew. Chem., Int. Ed. 1996, 35, 1723; (c) Ojima,
I. Acc. Chem. Res. 1995, 28, 383; (d) Ojima, I.; Habus, I.;
Zhao, M.; Zucco, M.; Park, Y. H. Tetrahedron 1992, 48, 6985.
4. (a) Wang, Y.; He, Q.-F.; Wang, H.-W.; Zhou, X.; Huang, Z.-Y.;
Qin, Y. J. Org. Chem. 2006, 71, 1588; (b) Fujieda, H.; Hata, S.;
Yamada, K.; Tomioka, K. Heterocycles 2005, 66, 611; (c)
Tosaki, S.; Tsuji, R.; Ohshima, T.; Shibasaki, M. J. Am.
Chem. Soc. 2005, 127, 2147; (d) Kudyba, I.; Raczko, J.;
Jurczak, J. J. Org. Chem. 2004, 69, 2844; (e) Borah, J. C.;
Gogoi, S.; Boruwa, J.; Kalita, B.; Barua, N. C. Tetrahedron
Lett. 2004, 45, 3689; (f) Castagnolo, D.; Armaroli, S.;
Corelli, F.; Botta, M. Tetrahedron: Asymmetry 2004, 15, 941;
(g) Juhl, K.; Jorgensen, K. A. J. Am. Chem. Soc. 2003, 124,
2420; (h) Aggarwal, V. K.; Vasse, J. L. Org. Lett. 2003, 5,
3987; (i) Choudary, B. M.; Chowdari, N. S.; Madhi, S.;
Kantam, M. L. J. Org. Chem. 2003, 68, 1736; (j) Ha, H.-J.;
Ahn, Y.-G.; Woo, J.-S.; Lee, G. S.; Lee, W. K. Bull. Chem.
Soc. Jpn. 2001, 74, 1667; (k) Hamamoto, H.; Mamedov,
V. A.; Kitamoto, M.; Hayashi, N.; Tsuboi, S. Tetrahedron:
5. Our other asymmetric synthesis of b-amino acid derivatives:
(a) Sakai, T.; Kawamoto, Y.; Tomioka, K. J. Org. Chem.
2006, 71, 4706; (b) Sakai, T.; Doi, H.; Tomioka, K.
Tetrahedron 2006, 62, 8351; (c) Doi, H.; Sakai, T.; Yamada,
K.; Tomioka, K. Chem. Commun. 2004, 1850; (d) Sakai, T.;
Doi, M.; Kawamoto, Y.; Yamada, K.; Tomioka, K.
Tetrahedron Lett. 2004, 45, 9261; (e) Doi, H.; Sakai, T.;
Iguchi, M.; Yamada, K.; Tomioka, K. J. Am. Chem. Soc.
2003, 125, 2886.
6. Anderson, J. C.; Smith, S. C. Synlett 1990, 107.
7. Review of oxaziridines: Davis, F. A.; Chen, B. C. Chem. Rev.
1992, 919.
8. All new compounds described in this paper showed satisfactory
spectroscopic and analytical data.
9. Davis, F. A.; Ultaowski, T. G.; Haque, M. S. J. Org. Chem.
1987, 52, 5288.
10. Holton, R. A.; Kim, H.-B.; Somoza, C.; Liang, F.; Biediger,
R. J.; Boatman, P. D.; Shindo, M.; Smith, C. C.; Kim, S.;
Nadizadeh, H.; Suzuki, Y.; Tao, C.; Vu, P.; Tang, S.; Zhang,
P.; Murthi, K. K.; Gentile, L. N.; Liu, J. H. J. Am. Chem.
Soc. 1994, 116, 1599.
11. (a) Kim, S.-C.; Kim, H.-K. Bull. Korean Chem. Soc. 2000, 21,
1047; (b) Ojima, I.; Sun, C. M.; Zucco, M.; Park, Y. H.; Duclos,
O.; Kuduk, S. Tetrahedron Lett. 1993, 34, 4149.
12. (a) Song, C. E.; Lee, S. W.; Roh, E. J.; Lee, S.-G.; Lee, W.-K.
ꢀ
Tetrahedron: Asymmetry 1998, 9, 983; (b) Fernandez, R.;
Ferrete, A.; Lassaletta, J. M.; Llera, J. M.; Martın-Zamora, E.
ꢀ
Angew. Chem., Int. Ed. 2002, 41, 831.