Enantioselective construction of bicyclo[3.1.0]hexane derivatives through asymmetric deprotonation of meso-cyclic ketones

Article abstract of DOI:10.1016/S0957-4166(02)00405-6

An efficient asymmetric synthesis of bicyclo[3.1.0]hexane derivatives was achieved. The three-step conversion of 6-hydroxytricyclo[3.2.1.0^2,7]octan-3-one 2, (derived from 3-oxatricyclo[3.3.1.0^2,4]nonan-7-one 1 through an asymmetric d

Full text of DOI:10.1016/S0957-4166(02)00405-6

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 13 (2002) 1519–1527
Enantioselective construction of bicyclo[3.1.0]hexane derivatives
through asymmetric deprotonation of meso-cyclic ketones
Hitoshi Abe,* Takenori Tsujino, Kenta Araki, Yasuo Takeuchi and Takashi Harayama*
Faculty of Pharmaceutical Sciences, Okayama University, Tsushima-Naka, Okayama 700-8530, Japan
Received 17 June 2002; accepted 15 July 2002
Abstract—An efficient asymmetric synthesis of bicyclo[3.1.0]hexane derivatives was achieved. The three-step conversion of
6-hydroxytricyclo[3.2.1.02,7]octan-3-one 2, (derived from 3-oxatricyclo[3.3.1.02,4]nonan-7-one 1 through an asymmetric deprotona-
tion reaction) led to 6 in optically active form. Alternatively, the asymmetric deprotonation reaction of meso-cyclic ketones 9a and
9b with several chiral lithium amide bases was examined to give silyl enol ether 12 and triflate 21 with high enantioselectivity. The
absolute configuration of the triflate 21 was determined by investigation of the chemical relationship between 21 and 6. © 2002
Elsevier Science Ltd. All rights reserved.
1. Introduction
effective for constructing optically active bicyclo[3.1.0]
compounds.
The enantioselective deprotonation reaction of meso-
type carbonyl compounds is a useful technique for the
desymmetrization of symmetric molecules. Lithium
amide bases derived from chiral secondary amines are
often employed for this purpose.1 Non-racemic enolate
formation, by the use of the chiral lithium amide base,
has been applied to the asymmetric syntheses of various
natural products.2
2. Results and discussion
2.1. Conversion of 6-hydroxytricyclo[3.2.1.02,7]octan-3-
one (2) into the bicyclo[3.1.0]hexane system
Recently, we demonstrated an efficient asymmetric
transformation of meso-epoxy ketone 1 into tricyclic
keto alcohol 2.6 In the presence of LiCl, a chiral lithium
amide (S,S)-37 was an effective reagent for this trans-
formation involving an enantioselective deprotonation-
transannular CꢀC bond formation process, to give 2
with high enantioselectivity (Scheme 1). We expected
that further transformation of the tricyclic hydroxy
ketone 2 would allow easy construction of the bicy-
clo[3.1.0]system by cleavage of the C(3)ꢀC(4) bond.
The bicyclo[3.1.0]hexane system is known to be an
efficient intermediate for the synthesis of natural prod-
ucts or biologically active compounds.3 The enantiose-
lective formation of the bicyclo[3.1.0] skeleton has been
developed particularly in the field of carbenoid chem-
istry.4 Enzymatic manipulation for the asymmetric syn-
thesis of the bicyclo[3.1.0] system has also been
demonstrated.5
Enantioselective deprotonation was expected to be an
efficient method for the preparation of the bicy-
clo[3.1.0]hexane system in asymmetric form. In this
article, we demonstrate that the desymmetrization of
meso-cyclic ketones, by use of chiral lithium amides, is
* Corresponding authors. Tel.: +81-86-251-7965; fax: +81-86-251-
7926 (H.A.); Tel.: +81-86-251-7963; fax: +81-86-251-7963 (T.H.);
e-mail: abe@pharm.okayama-u.ac.jp; harayama@pharm.okayama-
u.ac.jp
Scheme 1. Enantioselective deprotonation of 1.
0957-4166/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(02)00405-6

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H. Abe et al. / Tetrahedron: Asymmetry 13 (2002) 1519–1527
As shown in Scheme 2, after protection of the hydroxy
group with benzyl bromide, oxidation with selenium
dioxide was carried out to give a-diketone 5. Cleavage
of the CꢀC bond of 5 with lead tetraacetate successfully
afforded diester 6, which furnishes the bicyclo[3.1.0]
core in asymmetric form.
Scheme 3. Preparation of meso-ketones 9a and 9b.
nol 10 was easily obtained from norbornadiene through
the Meinwald rearrangement.9 After protection by the
TBS (tert-butyldimethylsilyl) or TBDPS (tert-
butyldiphenylsilyl) group, 11a and 11b were converted
to the meso-ketones 9a and 9b, respectively, by the
following sequence: hydration by the hydroboration–
oxidation process, oxidation with PDC (pyridinium
dichromate), and separation of the two regioisomers by
chromatography.
Scheme 2. Transformation of (+)-2 into 6.
2.2. Enantioselective deprotonation of meso-bicyclo-
The deprotonation reaction of 9a was first examined
using several chiral amide bases, (S,S)-3,7 (R)-13,10
(S)-14,11 (S)-15,11 and (1R,2S)-16,12 in the presence of
HMPA (hexamethylphosphoramide) or lithium chlo-
ride at −78°C. The results are summarized in Table 1.
In order to trap the resulting enolate, an internal
quenching method was employed (runs 1–5).13 The best
result was observed when (S,S)-3 was used as the amide
base in the presence of lithium chloride (run 1).
Although higher enantioselectivity was observed in the
case of (R)-13, the yield of the product was relatively
low (run 2). (1S,2R)-16 was afforded a poor yield and
low enantioselectivity (run 5). Under the other condi-
tions, none of the desired silyl enol ether was obtained
(runs 3, 4 and 6).
[3.1.0]hexan-3-one derivatives
Horenstein et al. reported that a CMP-NeuAc (cytidine
monophosphate N-acetylneuraminic acid) analog 7,
which was considered as a transition-state mimic of a
sialyl donor, exhibited strong activity for sialyltrans-
ferase inhibition.8 In their study, however, a bicyclic
alcohol 8 was synthesized in racemic form as a key
intermediate for the preparation of 7. Therefore, the
phosphates 7a and 7b were generated as an inseparable
mixture in a 1:1 ratio; the inhibitory effect was investi-
gated using the mixture of the diastereomers.8 Conse-
quently, the relationship between stereochemical
structure and biological activity remains unclear. We
thought it was necessary to clarify the effect of the
stereochemistry of 7 to the sialyltransferase inhibition.
For this purpose, enantioselective preparation of 8 was
essential for the synthesis of both enantiomerically pure
7a and 7b. In order to perform the enantioselective
synthesis of the bicyclo[3.1.0] system, the asymmetric
deprotonation process of meso-bicyclo[3.1.0]hexan-3-
one derivatives was investigated.
The ee (enantiomeric excess) of the silyl enol ether 12
was determined based on 1H NMR analysis of the
(R)-MTPA
(a-methoxy-a-(trifluoromethyl)phenyl-
acetyl) ester 18, which was derived from 12 by a
two-step conversion. Treatment of 12 with m-CPBA
(meta-chloroperbenzoic acid) afforded a-hydroxy
ketone 17 as the sole product. The next esterification
with (R)-MTPA was also successful when a DCC (dicy-
clohexylcarbodiimide)–DMAP (N,N-dimethylaminopy-
ridine) system was used. The two diastereomers of 18
1
were resolved in the H NMR spectrum; thus the ee of
12 could be determined.
In order to be able to prepare 8, the synthesis of the
triflate 19 was required. Unfortunately, all attempts to
convert 12 into 19 failed.
The meso-ketones substrates, 9a and 9b, were prepared
by the reported method (Scheme 3).8 A starting carbi-

H. Abe et al. / Tetrahedron: Asymmetry 13 (2002) 1519–1527
Table 1. Asymmetric deprotonation of 9a
1521
Run
Lithium amide
Additive
Time
Producta
Yield (%)
Ee (%)b
1
2
3
4
(S,S)-3
(R)-13
(S)-14
(S)-15
(1R,2S)-16
(1R,2S)-16
LiCl
LiCl
HMPA
HMPA
HMPA
LiCl
20 min
1 h
2 h
2 h
2 h
(+)-12
(−)-12
52
21
–
–
15
–
86
87
–
–
12
–
c
–
–
c
5
(+)-12
6d
2 h
–
c
a Absolute configuration was not determined.
b Ee was determined by the 1H NMR integration of the corresponding (R)-MTPA ester 18: See text.
c Not detected.
d External quenching method was used.
As an alternative, we employed triflating agent 20 to
trap the generated chiral enolate.14 Table 2 lists the
selected experiments of the enantioselective deprotona-
tion–triflation reaction using the TBDPS-protected
meso-ketone 9b as a substrate.
On the other hand, reduction of 6 with DIBAL gave
diol 26 in good yield, which was successfully silylated to
afford 27. However, the hydrogenolysis of benzyl ether
27 did not give the debenzylated product 25 in satisfac-
tory yield. In contrast to this result, the hydrogenolysis
of 26, followed by silylation of the two primary
hydroxy groups, gave (−)-25 in acceptable yield
(Scheme 5). By comparison of the signs of the specific
rotation, the stereochemistry of (−)-25 implied the mir-
ror image of (+)-25, which was described in Scheme 4.
Therefore, the absolute configuration of (−)-21 was
unambiguously determined.
The chiral lithium amide (S,S)-3 was an effective base
for enantioselectivity (run 1). When (R)-13 was
employed as the chiral base, the optimum ee was
observed although the yield was low (run 2).
The absolute configuration of (−)-21 was elucidated by
the investigation of the chemical relationship with 6
which was defined in stereochemistry.6 The triflate (−)-
21 was transformed to the homologated ester 22 by a
palladium-catalyzed carbonylation reaction. The treat-
ment of 22 with DIBAL (diisobutylaluminum hydride)
followed by silylation of the generated hydroxy group
was successful. A sequence of hydroboration with 9-
BBN (9-borabicyclo[3.3.1]nonane) and oxidation pro-
ceeded regio- and stereoselectively to give (+)-25,
having a positive specific rotation (Scheme 4).
Further studies on the synthesis of enantiomerically
pure 7a and 7b are now in progress.
3. Experimental
Melting points were measured using a Yanagimoto
micro melting point hot-plate apparatus and are uncor-
rected. IR spectra were recorded on a JASCO A-102 or
Table 2. Asymmetric deprotonation of 9b
Run
Lithium amide
Product
Yield (%)
Ee (%)a
1
2
(S,S)-3
(R)-13
(+)-21
(−)-21
32
43
75
77
a Ee (%) was determined by HPLC analysis using a chiral column (Daicel CHIRALCEL OD).

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H. Abe et al. / Tetrahedron: Asymmetry 13 (2002) 1519–1527
Scheme 4. Transformation of (−)-21 into (+)-25.
Scheme 5. Transformation of 6 into (−)-25.
FTIR-350 spectrophotometer. NMR spectra were
obtained using a Varian VXR-500 or VXR-200 instru-
ment. The chemical shifts are reported as l ppm and
couplings expressed in Hertz. FAB-MS were recorded
with a VG-70SE instrument using m-nitrobenzyl alco-
hol as the matrix. Elemental analyses were carried out
on a Yanaco MT-5 CHN analyzer. Optical rotations
were obtained on a JASCO DIP-1000 polarimeter. Sil-
ica gel column chromatography was carried out with
Wako-gel C-200. Merck Silica gel 60 F254 plates (No.
5744) were used for preparative TLC. THF (tetra-
hydrofuran) was used after distillation over sodium–
benzophenone ketyl. Chiral amines were purchased or
synthesized by reported methods.7,10–12 All reactions
were carried out under an argon atmosphere, unless
stated otherwise.
sulfate. Evaporation of the solvent gave a residue,
which was subjected to silica gel column chromatogra-
phy with ether–hexane (1:1) to afford 4 as a crystalline
solid (461 mg, 75%). For an analytical sample, recrys-
tallization from dichloromethane–ether was carried out
to give colorless needles, mp 65–67°C. IR (KBr) cm−1:
1
1690 (CꢁO), 1080 (C-O). H NMR (500 MHz, CDCl3)
l: 1.65 (1H, d, J=12.0), 1.86 (1H, t, J=8.0), 2.01 (1H,
ddd, J=1.0, 2.0, 19.0), 2.08 (1H, dd, J=3.0, 19.0),
2.14–2.20 (2H, m), 2.30–2.35 (2H, m), 3.83 (1H, s) 4.59
(2H, d, J=2.0), 7.30–7.32 (1H, m), 7.34–7.36 (4H, m).
13C NMR (125 MHz, CDCl3) l: 22.92, 26.60, 28.52,
32.36, 33.55, 41.96, 70.76, 81.81, 127.51, 127.65, 128.37,
138.07, 207.37. FAB-MS (positive ion mode) m/z: 229
[M+1]+, 457 [2M+1]+. [h]D30 −3.2 (c 0.50, CHCl3) [88%
ee]. Anal. calcd for C15H16O2: C, 78.92; H, 7.06. Found:
C, 78.93; H, 6.77%. The ee was determined by HPLC
analysis with a chiral column (Daicel CHIRALCEL
OD); eluent, isopropyl alcohol–hexane (1:1); flow rate,
0.2 ml/min; tR=31.7 and 34.1 min.
3.1. (1R,2R,5R,6R,7S)-6-Benzyloxytricyclo[3.2.1.02,7]-
octan-3-one, 4
NaH (60% in mineral oil, 241 mg, 6.03 mmol), TBAI
(tetra-n-butylammonium iodide) (501 mg, 1.34 mmol),
and benzyl bromide (850 ml, 7.15 mmol) were succes-
sively added to a solution of (+)-2 (370 mg, 2.68 mmol)
in THF (2 ml) at 0°C. The mixture was allowed to
warm to room temperature, and stirred for 5 h. After
cooling to 0°C, water was slowly added. The mixture
was extracted with ether, and then the organic layer
was washed with brine and dried over magnesium
3.2. (1R,2R,5S,6S,7S)-6-Benzyloxytricyclo[3.2.1.02,7]-
octane-3,4-dione, 5
A mixture of 4 (785 mg, 3.44 mmol), selenium dioxide
(524 mg, 4.72 mmol), and acetic acid (50 ml) was
heated under reflux for 1 h, and then poured into water.
After extraction with ether, the organic layer was
washed with saturated potassium carbonate aqueous

H. Abe et al. / Tetrahedron: Asymmetry 13 (2002) 1519–1527
1523
solution and brine and dried over magnesium sulfate.
Evaporation of the solvent gave a yellow solid which
was recrystallized from dichloromethane–ether to
afford 5 as yellow needles (684 mg, 82%), mp 122.5–
124°C. IR (KBr) cm−1: 1740 (CꢁO), 1720 (CꢁO), 1080
2.56 (1H, m), 3.40 (1H, dd, J=7.8, 11.2), 3.49 (1H, dd,
J=6.4, 11.2), 5.55–5.58 (1H, m), 5.64–5.69 (1H, m).
3.5. ( )-6a-(tert-Butyldiphenylsilyloxymethyl)-1a,5a-
bicyclo[3.1.0]hex-2-ene, 11b8
1
(C-O). H NMR (500 MHz, CDCl3) l: 2.22 (1H, d,
J=13.5), 2.31 (1H, t, J=7.5), 2.51–2.57 (2H, m), 2.64
(1H, ddd, J=3.0, 5.5, 13.5), 3.17 (1H, d, J=5.0), 4.22
(1H, s), 4.58 (1H, d, J=12.0), 4.63 (1H, d, J=12.0),
7.30–7.39 (5H, m). 13C NMR (125 MHz, CDCl3) l:
26.97, 27.80, 32.00, 32.19, 51.19, 71.52, 79.04, 127.71,
128.09, 128.58, 137.11, 190.00, 192.82. FAB-MS (posi-
tive ion mode) m/z: 243 [M+1]+. [h]D22 −80.4 (c 1.00,
CHCl3). Anal. calcd for C15H14O3: C, 74.36; H, 5.82.
Found: C, 74.17; H, 5.72%.
TBDPSCl (4.16 ml, 16.0 mmol) was added to a solution
of 10 (1.47 g, 13.3 mmol) and imidazole (2.27 g, 33.3
mmol) in DMF (3 ml) at 0°C. The reaction mixture was
allowed to warm to room temperature, stirred for 30
min and poured into water. After extraction with hex-
ane, the organic layer was washed with brine, dried
over magnesium sulfate and evaporated to give a
residue. Silica gel column chromatography with ether–
hexane (1:30) afforded 11b as a colorless oil (4.09 g,
1
88%). H NMR (200 MHz, CDCl3) l: 1.03 (9H, s),
1.15–1.34 (1H, m), 1.56–1.69 (1H, m), 1.96–2.07 (2H,
m), 2.34–2.48 (1H, m), 3.42–3.59 (2H, m), 5.39–5.41
(1H, m), 5.49–5.54 (1H, m), 7.31–7.44 (6H, m), 7.65–
7.70 (4H, m).
3.3. Dimethyl (1S,2S,3S,5R,6R)-2-benzyloxybicyclo-
[3.1.0]hexane-3,6-dicarboxylate, 6
Lead tetraacetate (90%, 1.37 g, 2.77 mmol) was added
to a solution of 5 (607 mg, 2.51 mmol) in methanol (30
ml), and the mixture was stirred for 1.5 h at room
temperature. After evaporation of the solvent,
dichloromethane and saturated aqueous sodium bicar-
bonate solution were successively added to the residue.
The resulting emulsion was passed through a Celite
pad, and then extracted with dichloromethane. The
organic layer was dried over magnesium sulfate and
evaporated. The residue was subjected to silica gel
column chromatography with ether–hexane (1:2) to
give 6 as a colorless oil (700 mg, 92%). IR (neat) cm−1:
3.6. a-(tert-Butyldimethylsilyloxymethyl)-1a,5a-
bicyclo[3.1.0]hexan-3-one, 9a8
BH3·SMe2 (2.27 ml, 23.9 mmol) was added to a solu-
tion of 11a (9.76 g, 43.5 mmol) in THF (80 ml) at 0°C.
The mixture was allowed to warm to room tempera-
ture, and allowed to stand for 45 min. Methanol (6 ml)
and 3N sodium hydroxide aqueous solution (8.70 ml)
were added to the mixture portionwise and 31% hydro-
gen peroxide aqueous solution was slowly added. The
reaction mixture was heated under reflux for 1 h,
poured into water, and extracted with ether. The
organic layer was combined, washed with brine and
dried over magnesium sulfate. Evaporation of the sol-
vent gave a residue which was subjected to silica gel
column chromatography with ethyl acetate–hexane
(1:4). The resulting colorless oil (8.29 g) was dissolved
in dichloromethane (30 ml). The solution was added
dropwise to a suspension of PDC (25.7 g, 68.4 mmol)
and HYFLO SUPER CEL® (25 g) in dichloromethane
(150 ml) at 0°C, and the mixture was allowed to warm
to room temperature. After stirring for 15 h, ether was
added to the mixture and the reaction mixture was
filtered. The filtrate was poured into water and
extracted with ether. The organic layer was dried over
magnesium sulfate and evaporated to give a residue,
which was subjected to silica gel column chromatogra-
phy with ether–hexane (1:8). Symmetric ketone 9a was
obtained as a colorless oil (5.02 g, 48%). IR (neat) cm−1:
1
1730 (CꢁO), 1200 (C-O), 1160 (C-O). H NMR (500
MHz, CDCl3) l: 1.78 (1H, t, J=8.5), 1.98–2.05 (2H,
m), 2.15 (1H, ddd, J=1.5, 7.0, 14.5), 2.49 (1H, ddd,
J=6.0, 12.0, 14.5), 3.38 (1H, ddd, J=4.5, 7.0, 12.0),
3.64 (3H, s), 3.73 (3H, s), 4.62 (1H, d, J=4.5), 4.62
(1H, d, J=12.0), 4.66 (1H, d, J=12.0), 7.28–7.39 (5H,
m). 13C NMR (125 MHz, CDCl3) l: 24.08, 26.22,
26.88, 32.10, 51.50, 51.80, 57.67, 72.10, 83.09, 127.54,
127.77, 128.30, 138.31, 171.29, 173.99. [h]2D6 −11.7 (c
1.04, CHCl3) [95% ee]. HRMS (FAB) calcd for
C17H21O5 [M+1]+: 305.1389. Found: 305.1404%. The ee
was determined by HPLC analysis with a chiral column
(Daicel CHIRALCEL OD); eluent, isopropyl alcohol–
hexane (1:30); flow rate, 0.5 ml/min; tR=21.0 and 24.5
min.
3.4. ( )-6a-(tert-Butyldimethylsilyloxymethyl)-1a,5a-
bicyclo[3.1.0]hex-2-ene, 11a8
1
1743 (CꢁO), 1079 (C-O). H NMR (200 MHz, CDCl3)
TBSCl (4.27 g, 28.3 mmol) was added to a solution of
10 (2.60 g, 23.6 mmol) and imidazole (4.02 g, 59.0
mmol) in DMF (5 ml) at 0°C. The reaction mixture was
allowed to warm to room temperature, stirred for 30
min, and poured into water. After extraction with
hexane, the organic layer was washed with brine, dried
over magnesium sulfate, and evaporated to give a
residue. Silica gel column chromatography with ether–
hexane (1:40) afforded 11a as a colorless oil (5.30 g,
100%). IR (neat) cm−1: 1093 (C-O). 1H NMR (200
MHz, CDCl3) l: 0.03 (6H, s), 0.88 (9H, s), 1.12–1.26
(1H, m), 1.62–1.73 (1H, m), 2.04–2.17 (2H, m), 2.42–
l: 0.03 (6H, s), 0.87 (9H, s), 1.30 (1H, dddd, J=7.8,
7.8, 8.0, 8.0), 1.64–1.72 (2H, m), 2.22 (2H, dd, J=1.8,
18.8), 2.58 (2H, ddd, J=1.8, 4.6, 18.8), 3.51 (2H, d,
J=7.8). 13C NMR (125 MHz, CDCl3) l: −5.34, 15.79,
18.23, 22.39, 25.85, 37.51, 58.19, 219.31.
3.7. a-(tert-Butyldiphenylsilyloxymethyl)-1a,5a-bicyclo-
[3.1.0]hexan-3-one, 9b8
In a way similar to the above procedure, the ketone 9b
(2.13 g, 51%) was obtained as a colorless oil from 11b
(3.96 g, 11.4 mmol). IR (neat) cm−1: 1742 (CꢁO), 1111

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H. Abe et al. / Tetrahedron: Asymmetry 13 (2002) 1519–1527
1
(C-O). H NMR (200 MHz, CDCl3) l: 1.04 (9H, s),
1.30 (1H, dddd, J=7.8, 7.8, 8.0, 8.0), 1.56–1.72 (2H,
m), 2.15 (2H, d, J=21.0), 2.53 (2H, dd, J=4.4, 21.0),
3.56 (2H, d, J=7.8), 7.35–7.43 (6H, m), 7.63–7.68 (4H,
m). 13C NMR (125 MHz, CDCl3) l: 15.95, 19.13,
22.38, 26.75, 37.44, 59.06, 127.64, 129.63, 133.60,
135.45, 219.23.
22.71, 22.72, 25.85, 35.06, 58.47, 71.23, 218.92. [h]D26
−19.6 (c 1.09, CHCl3) [86% ee]. Anal. calcd for
C13H24O3Si: C, 60.89; H, 9.43. Found: C, 61.05; H,
9.26.
3.10. (R)-MTPA ester of (1R*,2R*,5R*,6S*)-6-(tert-
butyldimethylsilyloxymethyl)-2-hydroxybicyclo[3.1.0]-
hexan-3-one, 18
3.8. (1R*,5S*,6S*)-6-(tert-Butyldimethylsilyloxy-
methyl)-3-(trimethylsilyloxy)bicyclo[3.1.0]hex-2-ene,
(+)-12
(R)-MTPA (6.2 mg, 26.4 mmol) and DMAP (0.4 mg,
3.27 mmol) were added to a solution of 17 (4.5 mg, 17.6
mmol) in dichloromethane (2 ml) at room temperature.
DCC (7.3 mg, 35.4 mmol) was added to the mixture at
0°C and the resulting mixture was allowed to warm to
room temperature and stirred for 2 h. After evapora-
tion, silica gel column chromatography with ethyl acet-
ate–hexane (1:15) gave a mixture of two diastereomers
of 18 as an oil (8.2 mg, 99%). The diastereomeric ratio
was judged based on 1H NMR integration. Selected
signals of 1H NMR (200 MHz, CDCl3) l: 4.91 (s,
major diastereomer) and 5.07 (s, minor diastereomer).
In a typical procedure (run 1, Table 1), n-butyllithium
(1.56 M in hexane, 801 ml, 1.25 mmol) was added to a
stirred solution of (S,S)-bis(a-methylbenzyl)amine
hydrochloride (163 mg, 0.624 mmol) in THF (3 ml) at
−78°C. The mixture was stirred for 30 min at 0°C and
then cooled to −78°C. TMSCl (132 ml, 1.04 mmol) was
added to the lithium amide solution at the same tem-
perature. After 5 min, a solution of 9a (50.0 mg, 0.208
mmol) in THF (3 ml) was added dropwise via syringe.
The reaction mixture was stirred for 20 min at −78°C,
and saturated sodium bicarbonate aqueous solution
was added to the mixture. After extractive workup with
hexane, the extract was dried over sodium sulfate and
evaporated to give a residue which was subjected to
silica gel column chromatography with ether–hexane
(1:40). Silyl enol ether (+)-12 (33.7 mg, 52%) was
obtained as a colorless oil. IR (neat) cm−1: 1629 (CꢁC),
3.11. N-(5-Chloro-2-pyridyl)triflimide, 2014
This compound was prepared by a literature procedure.
3.12. (1R,5S,6S)-6-(tert-Butyldiphenylsilyloxymethyl)-
bicyclo[3.1.0]hex-2-ene-3-yl triflate, (−)-21
1
1224 (C-O), 1091 (C-O). H NMR (500 MHz, CDCl3)
l: 0.05 (6H, s), 0.20 (9H, s), 0.90 (9H, s), 1.07 (1H,
dddd, J=6.5, 7.0, 7.5, 8.0), 1.43 (1H, qd, J=8.0, 1.0),
1.84–1.87 (1H, m), 2.09 (1H, ddd, J=0.5, 1.5, 17.5),
2.50 (1H, ddd, J=1.0, 8.0, 17.5), 3.56 (1H, dd, J=6.5,
11.0), 3.60 (1H, dd, J=7.5, 11.0), 4.62 (1H, ddd, J=
1.0, 1.0, 1.5). 13C NMR (125 MHz, CDCl3) l: −5.10,
−5.02, −0.07, 14.71, 18.43, 23.66, 23.77, 26.03, 33.24,
57.89, 100.44, 155.69. [h]2D6 +59.6 (c 1.16, CHCl3) [86%
ee]. Anal. calcd for C16H32O2Si2: C, 61.48; H, 10.32.
Found: C, 61.93; H, 9.92%.
In a typical procedure (run 2, Table 2), n-butyllithium
(1.59 M in hexane, 723 ml, 1.15 mmol) was added to a
stirred solution of (R)-N-(2,2,2)-trifluoroethyl)-1-
phenylethylamine hydrochloride (138 mg, 0.576 mmol)
in THF (3 ml) at −78°C. The mixture was stirred for 30
min at 0°C, and then cooled to −78°C. A solution of 9b
(70.0 mg, 0.192 mmol) in THF (3 ml) was added
dropwise to the lithium amide solution at the same
temperature, and the resulting mixture was stirred for 1
h. A solution of 20 (151 mg, 0.384 mmol) in THF (1.5
ml) was added via syringe and the mixture was stirred
for 1.5 h. After water was added, the mixture was
allowed to warm to room temperature and extracted
with ether. The extract was washed with 10% aqueous
sodium hydroxide solution, dried over potassium car-
bonate and evaporated to give a residue, which was
subjected to silica gel column chromatography with
ether–hexane (1:100). Triflate (−)-21 was obtained as a
colorless oil (40.7 mg, 43%). IR (neat) cm−1: 1644
3.9. (1R*,2R*,5R*,6S*)-6-(tert-Butyldimethylsilyl-
oxymethyl)-2-hydroxybicyclo[3.1.0]hexan-3-one, 17
A solution of (+)-12 (40.0 mg, 0.128 mmol) in
dichloromethane (2 ml) was added to a mixture of
m-CPBA (80%, 27.6 mg, 0.128 mmol), sodium bicar-
bonate (53.8 mg, 0.640 mmol) and dichloromethane (3
ml) at 0°C. After stirring for 20 min, ether (5 ml) and
10% sodium hydroxide aqueous solution (3 ml) were
added, and the mixture was allowed to warm to room
temperature and vigorously stirred for 3 h. The result-
ing mixture was extracted with ether, dried over magne-
sium sulfate and evaporated to give a residue. Silica gel
column chromatography with ether–hexane (1:1) afford
17 as a colorless oil (18.1 mg, 55%). IR (neat) cm−1:
1
(CꢁC), 1425 (SꢁO), 1213 (C-F), 1141 (SꢁO). H NMR
(500 MHz, CDCl3) l: 1.04 (9H, s), 1.35 (1H, dddd,
J=7.0, 7.0, 7.5, 8.0), 1.61 (1H, ddd, J=7.0, 7.5, 8.0),
1.92–1.95 (1H, m), 2.33 (1H, dd, J=1.5, 17.5), 2.72
(1H, dd, J=8.5, 17.5), 3.61 (1H, dd, J=7.5, 11.5), 3.66
(1H, dd, J=7.0, 11.5), 5.45 (1H, m), 7.36–7.42 (6H, m),
7.65–7.68 (4H, m). 13C NMR (125 MHz, CDCl3) l:
15.95, 19.19, 22.64, 23.45, 26.80, 31.02, 57.69, 117.58,
127.61, 127.64, 129.63, 133.84, 135.56, 147.99. [h]D26
−57.8 (c 0.92, CHCl3) [77% ee]. Anal. calcd for
C24H27F3O4SSi: C, 58.04; H, 5.48. Found: C, 58.07; H,
5.75%. The ee was determined by HPLC analysis with
a chiral column (Daicel CHIRALCEL OD); eluent,
hexane; flow rate, 0.5 ml/min; tR=15.7 and 16.6 min.
1
3396 (-OH), 1751 (CꢁO), 1083 (C-O). H NMR (200
MHz, CDCl3) l: 0.03 (6H, s), 0.87 (9H, s), 1.46 (1H,
dddd, J=7.0, 7.2, 8.0, 9.2), 1.70 (1H, dd, J=7.2, 9.2),
1.81 (1H, ddd, J=6.4, 7.2, 7.2), 2.28 (1H, d, J=20.0),
2.49 (1H, bs), 2.74 (1H, dd, J=6.4, 20.0), 3.48 (1H, dd,
J=8.0, 11.6), 3.60 (1H, dd, J=7.0, 11.6), 3.82 (1H, s).
13C NMR (125 MHz, CDCl3) l: −5.38, 15.74, 18.25,

H. Abe et al. / Tetrahedron: Asymmetry 13 (2002) 1519–1527
1525
3.13. Methyl (1S,5S,6S)-6-(tert-butyldiphenylsilyloxy-
0.638 mmol) in DMF (3 ml) at 0°C. The mixture was
stirred for 1 h at room temperature, poured into water,
extracted with hexane. The organic layer was washed
with brine, dried over magnesium sulfate and evapo-
rated to give a residue, which was subjected to silica gel
column chromatography with ethyl acetate–hexane
(1:40) to afford 24 (155 mg, 98%). For an analytical
sample, recrystallization from hexane was carried out to
afford colorless prisms, mp 74–75°C. IR (KBr) cm−1:
methyl)bicyclo[3.1.0]hex-2-ene-3-carboxylate, 22
A mixture of palladium(II) acetate (4.6 mg, 0.0203
mmol), triphenylphosphine (10.6 mg, 0.0404 mmol),
(−)-21 (335 mg, 0.675 mmol), triethylamine (188 ml, 1.35
mmol), methanol (1.09 ml, 27.0 mmol) and DMF (N,
N-dimethylformamide) (5 ml) was stirred for 24 h at
room temperature under a carbon monoxide atmo-
sphere. After addition of water, the mixture was
extracted with ether. The organic layer was washed
with water, dried over magnesium sulfate and evapo-
rated to give a residue. Silica gel column chromatogra-
phy with ethyl acetate–hexane (1:15) gave 22 as a
colorless oil (197 mg, 72%). IR (neat) cm−1: 1718
1
1111 (C-O). H NMR (200 MHz, CDCl3) l: 1.02 (18H,
s), 1.12–1.33 (1H, m), 1.59–1.71 (1H, m), 1.92 (1H, d,
J=17.6), 1.96–2.04 (1H, m), 2.48 (1H, dd, J=8.0,
17.6), 3.50 (2H, d, J=7.4), 3.95 (2H, s), 5.42 (1H, s),
7.28–7.42 (12H, m), 7.62–7.68 (8H, m). 13C NMR (50
MHz, CDCl3) l: 19.23, 19.35, 23.61, 26.80, 26.89,
27.92, 31.99, 58.60, 62.26, 123.10, 127.47, 127.61,
129.39, 129.56, 133.76, 134.21, 134.26, 135.51, 135.59,
144.29. [h]1D8 −60.5 (c 1.20, CHCl3) [82% ee]. Anal. calcd
for C40H48O2Si2: C, 77.87; H, 7.84. Found: C, 78.04; H,
7.84%. The ee was determined by HPLC analysis with
a chiral column (Daicel CHIRALCEL OD); eluent,
hexane; flow rate, 0.5 ml/min; tR=19.3 and 22.4 min.
1
(CꢁO), 1243 (C-O), 1104 (C-O). H NMR (200 MHz,
CDCl3) l: 1.03 (9H, s), 1.46 (1H, dddd, J=6.4, 7.8, 8.0,
8.2), 1.81 (1H, qd, J=8.0, 1.4), 2.08–2.18 (1H, m), 2.35
(1H, ddd, J=1.4, 2.0, 18.8), 2.67 (1H, ddd, J=2.0, 8.0,
18.8), 3.40 (1H, dd, J=8.2, 11.2), 3.56 (1H, dd, J=6.4,
11.2), 3.68 (3H, s), 6.62 (1H, q, J=2.0), 7.32–7.42 (6H,
m), 7.60–7.68 (4H, m). 13C NMR (50 MHz, CDCl3) l:
19.15, 21.40, 24.26, 26.79, 29.18, 31.04, 51.21, 57.83,
127.55, 129.48, 133.84, 133.88, 135.20, 135.54, 142.31,
164.82, 165.26. [h]2D2 −110.8 (c 1.27, CHCl3) [77% ee].
The ee was determined by HPLC analysis with a chiral
column (Daicel CHIRALCEL OD); eluent, isopropyl
alcohol–hexane (1:300); flow rate, 0.5 ml/min; tR=16.2
and 18.8 min.
3.16. (1R,2R,3S,5R,6S)-3,6-Bis(tert-butyldiphenylsilyl-
oxymethyl)bicyclo[3.1.0]hexan-2-ol, (+)-25
A solution of 24 (54.2 mg, 87.8 mmol) in THF (3 ml)
was added to a mixture of 9-BBN (0.5 M in THF, 526
ml, 0.263 mmol) and THF (2 ml). The mixture was
heated under reflux for 30 min, and cooled to 0°C.
Ethanol (0.3 ml), 3 M sodium hydroxide aqueous solu-
tion (0.2 ml) and 31% hydrogen peroxide aqueous
solution (0.2 ml) were successively added to the reac-
tion mixture. The mixture was heated under reflux for 1
h, poured into water, and extracted with ether. The
organic layer was dried over magnesium sulfate and
evaporated to give a residue. Silica gel column chro-
matography with ethyl acetate–hexane (1:8) gave (+)-25
as a colorless oil (31.0 mg, 56%). IR (neat) cm−1: 3391
3.14. (1S,5S,6S)-6-(tert-Butyldiphenylsilyloxymethyl)-3-
(hydroxymethyl)bicyclo[3.1.0]hex-2-ene, 23
DIBAL (1.0 M in toluene, 788 ml, 0.788 mmol) was
added dropwise to a solution of 22 (160 mg, 0.394
mmol) in toluene (5 ml) at −78°C, and the mixture was
allowed to warm to room temperature. After stirring
for 30 min, 10% sodium hydroxide aqueous solution
was added at 0°C, and the resulting mixture was stirred
for 5 min. The mixture was extracted with ether,
washed with brine, dried over magnesium sulfate and
evaporated. Purification by silica gel column chro-
matography with ethyl acetate–hexane (1:6) gave 23 as
a colorless oil (120 mg, 81%). IR (neat) cm−1: 3339
1
(-OH), 1112 (C-O). H NMR (500 MHz, CDCl3) l:
0.76 (1H, ddd, J=2.5, 11.0, 14.0), 1.02 (9H, s), 1.03
(9H, s), 1.20–1.27 (1H, m), 1.47 (1H, t, J=8.5), 1.55–
1.61 (1H, m), 1.85 (1H, ddd, J=7.5, 10.5, 14.0), 2.17
(1H, bs), 2.53–2.57 (1H, m), 3.26 (1H, t, J=9.5), 3.44–
3.48 (2H, m), 3.70–3.73 (2H, m), 7.27–7.42 (12H, m),
7.59–7.66 (8H, m). 13C NMR (125 MHz, CDCl3) l:
19.04, 19.19, 21.81, 24.49, 24.58, 26.85, 29.76, 59.78,
60.33, 65.02, 75.95, 127.53, 127.56, 127.73, 129.55,
129.75, 133.19, 133.21, 133.91, 133.94, 135.49, 135.60.
[h]2D2 +15.1 (c 1.44, CHCl3) [84% ee]. Anal. calcd for
C40H50O3Si2: C, 75.66; H, 7.94. Found: C, 75.65; H,
7.77%. The ee was determined by HPLC analysis with
a chiral column (Daicel CHIRALCEL OD); eluent,
isopropyl alcohol–hexane (1:200); flow rate, 0.5 ml/min;
tR=30.6 and 35.0 min.
1
(-OH), 1112 (C-O). H NMR (500 MHz, CDCl3) l:
1.04 (9H, s), 1.26–1.31 (1H, m), 1.65–1.70 (1H, m), 1.97
(1H, bd, J=17.5 Hz), 1.99–2.02 (1H, m), 2.43 (1H, dd,
J=8.0, 17.5), 3.40 (1H, dd, J=8.0, 11.0), 3.58 (1H, dd,
J=6.5, 11.0), 3.85 (2H, s), 5.35–5.36 (1H, m), 7.36–7.44
(6H, m), 7.66–7.68 (4H, m). 13C NMR (50 MHz,
CDCl3) l: 19.17, 19.38, 23.35, 26.83, 27.89, 31.89,
58.35, 61.07, 123.99, 127.45, 127.52, 129.50, 134.11,
135.61, 135.65, 144.59. [h]1D8 −109.3 (c 1.50, CHCl3)
[77% ee]. The ee was determined by HPLC analysis
with a chiral column (Daicel CHIRALCEL OD); elu-
ent, isopropyl alcohol–hexane (1:20); flow rate, 0.5 ml/
min; tR=12.9 and 14.0 min.
3.17. (1S,2S,3R,5S,6R)-2-Benzyloxy-3,6-bis(hydroxy-
methyl)bicyclo[3.1.0]hexane, 26
3.15. (1S,5S,6S)-3,6-Bis(tert-butyldiphenylsilyl-
oxymethyl)bicyclo[3.1.0]hex-2-ene, 24
DIBAL (1.0 M in toluene, 4.30 ml, 4.3 mmol) was
added dropwise to a solution of 6 (257 mg, 0.845 mmol)
in toluene (1 ml) at −78°C, and the mixture was allowed
to warm to room temperature. After stirring for 1 h,
TBDPSCl (80 ml, 0.308 mmol) was added to a solution
of 23 (96.4 mg, 0.255 mmol) and imidazole (43.4 mg,

1526
H. Abe et al. / Tetrahedron: Asymmetry 13 (2002) 1519–1527
the mixture was poured into 10% aqueous HCl solu-
tion, and extracted with ethyl acetate. The organic layer
was washed with brine, dried over magnesium sulfate
and evaporated. Purification by silica gel column chro-
matography with ethyl acetate–hexane (2:1) gave 26
(195 mg, 93%) which was recrystallized from
dichloromethane–hexane to afford colorless needles,
mp 109–110.5°C. IR (KBr) cm−1: 3246 (-OH). 1H NMR
(500 MHz, CDCl3) l: 1.17 (1H, ddd, J=2.5, 11.0,
14.0), 1.27 (1H, dddd, J=7.5, 8.0, 8.5, 8.5), 1.64–1.72
(2H, m), 1.83 (2H, bs), 2.10 (1H, ddd, J=7.0, 11.0,
14.0), 2.69–2.77 (1H, m), 3.60–3.66 (5H, m), 4.50 (1H,
d, J=11.5), 4.66 (1H, d, J=11.5), 7.28–7.37 (5H, m).
13C NMR (125 MHz, CDCl3) l: 21.87, 24.36, 24.60,
27.50, 57.72, 57.94, 62.85, 72.35, 81.49, 127.67, 127.78,
128.38, 138.17. [h]D22 +33.8 (c 1.24, CHCl3) [96% ee].
Anal. calcd for C15H20O3: C, 72.55; H, 8.12. Found: C,
72.24; H, 8.11%. The ee was determined by HPLC
analysis with a chiral column (Daicel CHIRALCEL
OJ); eluent, isopropyl alcohol–hexane (1:5); flow rate,
0.8 ml/min; tR=12.9 and 15.7 min.
organic layer was washed with brine, dried over magne-
sium sulfate and evaporated to give a residue. Silica gel
column chromatography with ethyl acetate–hexane
(1:8) gave (−)-25 (121 mg, 59%) as a colorless oil. [h]D14
−17.2 (c 1.79, CHCl3) [97% ee]. Other spectral data
were identical with those of (+)-25 described above. The
ee was determined by HPLC analysis with a chiral
column (Daicel CHIRALCEL OD); eluent, isopropyl
alcohol–hexane (1:200); flow rate, 0.5 ml/min; tR=30.6
and 35.0 min.
Acknowledgements
The authors thank the SC-NMR laboratory of
Okayama University for the high field NMR
experiments.
References
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diphenylsilyloxymethyl)bicyclo[3.1.0]hexane, 27
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(KBr) cm−1: 1110, 1070. H NMR (500 MHz, CDCl3)
l: 1.00 (9H, s), 1.04 (9H, s), 1.11–1.28 (3H, m), 1.52–
1.58 (1H, m), 2.04–2.10 (1H, m), 2.67–2.72 (1H, m),
3.40 (1H, dd, J=6.0, 11.0), 3.54 (1H, dd, J=6.0, 11.0),
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(1H, dd, J=8.0, 11.5), 4.38 (1H, d, J=7.5), 4.52 (1H, d,
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for C47H56O3Si2: C, 77.85; H, 7.78. Found: C, 78.02; H,
8.06. The ee was determined by HPLC analysis with a
chiral column (Daicel CHIRALCEL OD); eluent, iso-
propyl alcohol–hexane (1:30); flow rate, 0.1 ml/min;
tR=33.4 and 35.7 min.
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