Novel skeletal rearrangement of hydroindan derivatives into hydroazulenones via an alkoxy radical

Article abstract of DOI:10.1016/S0040-4020(02)00102-3

A novel construction of hydroazulenones using skeletal rearrangement of epoxy-hydroindan derivatives via alkoxy radical was developed. The reaction was also found to proceed without damage of acetal or olefin group.

Full text of DOI:10.1016/S0040-4020(02)00102-3

TETRAHEDRON
Pergamon
Tetrahedron 58 (2002) 2339±2350
Novel skeletal rearrangement of hydroindan derivatives into
hydroazulenones via an alkoxy radical
Mizuko Goto,a Irie Miyoshi,a Yusuke Ishii,a Yukie Ogasawara,a You-Ichirou Kakimoto,a
Shinji Nagumo,a Atsushi Nishida,a,² Norio Kawaharaa,p and Mayumi Nishidab,³
aHokkaido College of Pharmacy, Katuraoka 7-1, Otaru 047-0264, Japan
bFaculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
Received 26 November 2001; accepted 25 January 2002
AbstractÐA novel construction of hydroazulenones using skeletal rearrangement of epoxy-hydroindan derivatives via alkoxy radical was
developed. The reaction was also found to proceed without damage of acetal or ole®n group. q 2002 Elsevier Science Ltd. All rights
reserved.
1. Introduction
2. Results and discussion
In many cases, a free radical process is useful for C±C bond
formation even in the presence of functional groups incom-
patible with polar reagents.1 This advantage would also be
suitable for ring transformation of a complex molecule with-
out damage to functional groups. We have developed a new
radical reaction in which cycloalkanone 1 possessing an
acetylenic side chain rearranged to bicyclic ketone 2
(Scheme 1).2,3 In this transformation, stannylvinyl radical
a derived from 1 attacked the carbonyl group on the
proximate ring. The resulting alkoxy radical b was then
converted into a tertiary carbon-centered radical c through
a ring opening. The radical c was added to the proximate
stannylvinyl group, generating a secondary carbon-centered
radical d. Finally, the addition of the radical to the carbonyl
group followed by ring-opening afforded 2. The hydro-
azulenone 2 was successfully converted into diketone 3,
which is a synthetic intermediate of damsinic acid.2c One
of the key steps in this skeletal rearrangement is the forma-
tion of an alkoxy radical, which is alternatively generated
by homolytic cleavage of an epoxy ring as shown in
the radical sequence of thiocarbonylimidazolide 4 into
bicyclo[6.3.0]undecanone 5.4,5 We report here a new
method for constructing a hydroazulene skeleton, which is
present in a wide variety of natural sources, by radical ring
transformation of hydroindan epoxides 20, 21, 25, 29, 33
and 34.
Scheme 2 shows the preparation of hydroindenes 12±14,
which are precursors of hydroindan epoxides. Oxidation
of 66 with tetrapropyl-ammonium perruthenate (TPAP)
followed by addition of (carbethoxymethylene)triphenyl-
phosphorane gave ester 7, which was converted into 9
through a sequence of DIBAH reduction and oxidation.
Wittig reaction of 9 afforded diene 10, which was converted
into ester 11 upon treatment with MeLi followed by addition
of methyl chloroformate in situ.7 Intramolecular Diels±
Alder reaction8 of 11 was carried out in re¯uxing toluene
to give bicyclodiene 12. Because of its easy aromatization,
12 was subjected to OsO4 oxidation9 or diacetoxylation
without puri®cation. Dihydroxylation of 12 with OsO4
afforded diol 13. Treatment of 12 with CH3COOAg/I2
followed by alkaline hydrolysis gave the diastereomeric
diol 14,10 whose stereochemistry was determined by X-ray
analysis of the corresponding di-bromobenzoate 15 (Fig. 1).
Acetalization of 13 followed by DIBAH reduction gave
allyl alcohol 17, which was treated with m-CPBA to give
epoxides 18 and 19. These epoxides were easily separated
by column chromatography with silica gel. Epoxides 18 and
19 reacted with thiocarbonyl diimidazole to give 20 and 21,
respectively. On the other hand, silylation of 13 and 14 with
TESOTf afforded the corresponding silylethers 22 and 26.
Each compound was converted into thiocarbonyl imidazo-
lide 25 and 29 through a sequence of DIBAH reduction,
m-CPBA epoxidation and thiocarbonylation. In their
epoxidation, addition of NaHCO3 was essential for prevent-
ing cleavage of the epoxy ring. DIBAH reduction of diene-
ester 12 followed by epoxidation yielded diastereomeric
epoxides 31 (more polar) and 32 (less polar), which were
separated by column chromatography with silica gel.
Keywords: radical; skeletal rearrangement; hydroindan; hydroazulenone.
Corresponding author. Tel.: 181-134-62-1835; fax: 181-134-62-5161;
p
e-mail: kawahara@hokuyakudai.ac.jp
Present address: Faculty of Pharmaceutical Sciences, Chiba University,
²
1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
Present address: Koei Chemical Company Ltd, 25 Kitasode, Sodegaura-
shi, Chiba 299-0266, Japan.
³
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(02)00102-3

2340
M. Goto et al. / Tetrahedron58 (2002) 2339±2350
Scheme 1.
Stereochemistries of these compounds could not be deter-
mined. Epoxides were converted into the corresponding
thiocarbonyl imidazolides 33 and 3411 (Scheme 3)
determined by the combination of chemical conversion and
NOE experiments. Treatment of epoxide 18 with diethyl-
aluminium 2,2,6,6-tetramethylpiperidide (DATMP)12 gave
diol 35. On the other hand, ring opening of 24 and 28 was
performed by using TsOH´H2O to give diol 37 and 39. Diols
The relative con®guration of epoxides 18, 24 and 28 was
Ê
Scheme 2. Reagents: (a) (1) TPAP, NMO, MS4A (2) Ph3PvCHCOOEt;
Ê
(b) DIBAH, 2788C; (c) TPAP, NMO, MS4A; (d) Ph3PvCH2; (e) MeLi,
ClCOOMe, 2308C; (f) re¯ux to toluene; (g) OsO4, NMO, t-BuOH, H2O,
2208C; (h) (1) CH3COOAg, I2, AcOH (2) AcOH, H2O, re¯ux; (i) KOH;
(j) p-bromobenzoyl chloride, DMAP, pyridine.
Figure 1. X-Ray structure of 15.

M. Goto et al. / Tetrahedron58 (2002) 2339±2350
2341
Scheme 3. Reagents: (a) PPTS, 2,2-dimethoxypropane; (b) DIBAH, 2788C; (c) m-CPBA, 2208C; (d) thiocarbonyl diimidazole, re¯ux in 1,2-dichloroethane;
(e) TESOTf, 2,6-lutidine, 2158C; (f) MCPBA, NaHCO3, 2208C.
Scheme 4. Reagents: (a) DATMP; (b) thiocarbonyl diimidazole, re¯ux in 1,2-dichloroethane; (c) TsOH´H2O.

2342
M. Goto et al. / Tetrahedron58 (2002) 2339±2350
Table 1.
Run
Sub.
Method
Solvents
Temperature (8C)
Time (min)
Yield (%)
41
42
1
2
3
4
5
6
20
20
20
20
21
21
A
B
A
B
A
B
Benzene
Benzene
Toluene
Toluene
Toluene
Toluene
80
80
110
110
110
110
30
50
40
60
30
60
Trace
20
25
60
26
28
Trace
25
21
23
56
9
Method A. A solution of a substrate, AlBN and n-Bu3SnH in a solvent was re¯uxed. Method B. To a re¯uxing solution of a substrate in benzene or toluene was
slowly added a solution of AlBN and n-Bu3SnH in benzene or toluene by using a syringe pump. The resulting mixture was further re¯uxed.
35, 37 and 39 were converted into 36, 38 and 40, whose 1H
NMR spectra showed NOE correlations as shown in
Scheme 4.
cedure, another epoxide 21 was also converted into 41 in
56% yield along with 42. Stereochemistries of 41 and 42
were determined by NOE correlations as shown in Table 1.
The result of radical reaction of 20 and 21 is summarized in
Table 1. When a mixture of 20, n-Bu3SnH and AIBN in
benzene was heated at 808C, there was almost no formation
of the desired hydroazulenone 41. However, a-methyl-
hydroindanone 42 was obtained in 28% yield. Formation
of 41 was achieved by increasing the reaction temperature.
Treatment of 20 with n-Bu3SnH and AIBN in toluene at
1108C produced 41 (25%) and 42 (25%). Furthermore,
when a solution of n-Bu3SnH and AIBN in toluene was
added slowly to a heating solution of 20 in toluene, the
yield of 41 was drastically improved (60%). By this pro-
Next, radical skeletal rearrangement of two epimeric hydro-
indans 25 and 29 with silyloxy groups was carried out
(Scheme 5). Treatment of 25 with n-Bu3SnH in re¯uxing
toluene gave 43 in 57% yield. On the other hand, the
reaction of 29 afforded 44 and 45 along with a small amount
of 43. Hydroazulenone 46 having a double bond was
obtained from both epoxides 33 and 34 in good yield. The
double bond was also found to be compatible with these
reaction conditions.
Identi®cation of 43, 44 and 46 was carried out by chemical
Scheme 5. Conditions: (a) n-Bu3SnH, AlBN, toluene, 1108C, slow addition using a syringe pump.

M. Goto et al. / Tetrahedron58 (2002) 2339±2350
2343
Scheme 6. Reagents: (a) TBAF; (b) PPTS, 2,2-dimethoxypropane; (c) (1) CH3COOAg, I2, AcOH (2) KOH; (d) QsO4, NMO, t-BuOH, H2O, 2208C.
Scheme 7.
conversion (Scheme 6). Desilylation of 43 followed by
acetalization gave 41, whose structure had already been
determined. Enone 46 was subjected to oxidation with
CH3COOAg/I2 and subsequent alkaline hydrolysis, and
the resulting compound was identical to diol 47. On the
other hand, OsO4 oxidation of 46 yielded 48, which was
also obtained by desilylation of 44. Compound 45 was
found to be a trans-ring isomer by con®rming the NOE
correlation as shown in Scheme 5.
corresponding hydroazulenone compounds, while at lower
temperature, methyl radical I traps hydride to produce
hydroindanone 42. The interconversion between G and H
contributes to the stereochemistries of the products.
In conclusion, we have developed a new method for the
formation of hydroazulene compounds. The reaction was
found to proceed without damage to the acetal, silyl ether
and ole®n groups. This reaction would be applicable to
various compounds possessing incompatible functional
groups with polar reagents.
Scheme 7 shows a possible mechanism of the radical
skeletal rearrangement. Homolytic cleavage of epoxy
rings of methyl radicals A±C gives the corresponding
alkoxy radicals D±F. Nine-membered cyclic radical G is
formed by b-cleavage of D or E. On the other hand,
b-cleavage of F affords a nine-membered cyclic radical H.
Interconversion between G and H should be possible, but
the rate of interconversion would be very slow. Radical G or
H undertakes ring formation to form I or J, respectively. At
a higher temperature, methyl radicals I and J are converted
into K and L, which undertake ring expansion to give the
3. Experimental
3.1. General methods
Melting points were measured using a Yanaco micro melt-
ing point apparatus and were uncorrected. NMR spectra
were recorded on a JEOL JNM-GX270 spectrometer or a
JEOL JNM-ECP 500 FT-NMR with tetramethylsilane as

2344
M. Goto et al. / Tetrahedron58 (2002) 2339±2350
internal standard. Abbreviations are as follows: sˆsinglet,
dˆdoublet, tˆtriplet, qˆquartet, mˆmultiplet, and
brˆbroad. The electron impact mass spectra (EI-MS)
were measured using a Hitachi-M-2000 mass spectrometer,
and IR spectra were measured using a JASCO FT-IR7000 or
a JASCO A-102 IR spectrophotometer. Reactions were
followed by thin-layer chromatography (TLC) on Silica
gel 60 F254-precoated TLC plates. Silica gel used on column
chromatography was Silica gel 60 (Merck, 70±230 or 230±
400 mesh).
2.47 (2H, m), 2.30 (2H, t, Jˆ7.1 Hz), 1.74 (2H, quintet,
Jˆ7.1 Hz), 0.15 (9H, s). 13C NMR (68 MHz, CDCl3) d
193.7, 157.3, 133.3, 105.8, 85.6, 31.4, 26.6, 19.1, 0.0
(£3). IR (neat) 2700, 2160, 1680, 1630 cm21. EI-MS m/z
194 (M1). HR-MS m/z 194.1145 (Calcd for C11H18OSi:
194.1126).
3.1.4. (6E)-1-Trimethylsilylnona-6,8-dien-1-yne (10). To
a suspension of methyltriphenylphosphonium bromide
(95.0 g, 266 mmol) in THF (900 ml) was added dropwise
n-BuLi (1.64 M in hexane, 163 ml, 267 mmol) at 2208C
under an argon atmosphere. After being stirred for 30 min,
a solution of 9 (21.0 g, 108 mmol) in THF (150 ml) was
added to the mixture at 2208C. After 30 min, the reaction
mixture was quenched with H2O at 08C and extracted with
ether. The extract was washed with brine, dried over MgSO4
and concentrated under reduced pressure. The residue was
puri®ed by column chromatography on silica gel eluted with
pentane/ether (20/1) to give 10 (18.0 g, 93.8 mmol, 87%) as
3.1.1. Ethyl (2E)-8-trimethylsilyloct-2-en-7-ynoate (7).
To a mixture of 6 (36.0 g, 212 mmol), molecular sieves
Ê
4 A (80.0 g) and CH2Cl2 (1 l) was added N-methylmorpho-
line N-oxide (NMO, 35.0 g, 299 mmol) and tetrapropyl-
ammonium perruthenate (TPAP, 2.00 g, 5.69 mmol) at
room temperature. After being stirred for 1 h, (carbethoxy-
methylene)triphenylphosphorane (83.0 g, 238 mmol) was
added to the mixture. After 1.5 h, the reaction mixture
was diluted with ether and ®ltered through a celite pad.
The ®ltrate was concentrated under reduced pressure. The
residue was puri®ed by column chromatography on silica
gel eluted with hexane/AcOEt (15/1) to give 7 (43.0 g,
1
a yellow oil. H NMR (270 MHz, CDCl3) d 6.30 (1H, dt,
Jˆ16.9, 10.3 Hz), 6.07 (1H, dd, Jˆ15.1, 10.3 Hz), 5.68 (1H,
dt, Jˆ15.1, 7.1 Hz), 5.10 (1H, d, Jˆ16.9 Hz), 4.93 (1H, d,
Jˆ10.3 Hz), 2.27±2.14 (4H, m), 1.62 (2H, quintet,
Jˆ7.1 Hz), 0.15 (9H, s). Signals at 6.07, 5.10 and
4.93 ppm show also small couplings. 13C NMR (68 MHz,
CDCl3) d 137.0, 133.9, 131.6, 115.0, 107.0, 84.6, 31.3, 27.9,
19.1, 0.0 (£3). IR (neat) 2200, 1640, 1600 cm21. EI-MS m/z
192 (M1). HR-MS m/z 192.1303 (Calcd for C12H20Si:
192.1333).
1
181 mmol, 85%) as a colorless oil. H NMR (270 MHz,
CDCl3) d 6.94 (1H, dt, Jˆ15.7, 7.0 Hz), 5.84 (1H, dt,
Jˆ15.7, 1.5 Hz), 4.18 (2H, q, Jˆ7.1 Hz), 2.36±2.26 (2H,
m), 2.26 (2H, t, Jˆ7.0 Hz), 1.68 (2H, quintet, Jˆ7.0 Hz),
1.28 (3H, t, Jˆ7.1 Hz), 0.16 (9H, s). 13C NMR (68 MHz,
CDCl3) d 166.4, 147.9, 121.9, 106.2, 85.2, 60.1, 30.9, 26.8,
19.2, 14.2, 0.0 (£3). IR (neat) 2180, 1710, 1650 cm21
.
EI-MS m/z 238 (M1). HR-MS m/z 238.1382 (Calcd for
C13H22O2Si: 238.1388).
3.1.5. Methyl (7E)-deca-7,9-dien-2-ynoate (11). To a solu-
tion of 10 (3.40 g, 17.7 mmol) in THF (70 ml) was added
dropwise MeLi (1.06 M in ether, 33 ml, 35.0 mmol) at 08C
under an argon atmosphere. After being stirred for 1.5 h, the
resulting mixture was added dropwise to a solution of
methyl chloroformate (7 ml, 90.6 mmol) in THF (70 ml)
at 2308C under an argon atmosphere. After 30 min, the
reaction mixture was quenched with saturated aqueous
NH4Cl and extracted with ether. The extract was washed
with brine, dried over MgSO4 and concentrated under
reduced pressure. The residue was puri®ed by column
chromatography with silica gel eluted with pentane/ether
(20/1) to give 11 (2.10 g, 11.8 mmol, 67%) as a colorless
3.1.2. (2E)-8-Trimethylsilyloct-2-en-7-yn-1-ol (8). To a
solution of 7 (8.70 g, 36.6 mmol) in hexane (200 ml) was
added dropwise DIBAH (0.95 M in hexane, 84 ml,
79.8 mmol) at 2788C under an argon atmosphere. After
being stirred for 30 min, the reaction was quenched with
saturated aqueous NH4Cl. The reaction mixture was ®ltered
through a celite pad. The ®ltrate was dried over MgSO4 and
concentrated under reduced pressure. The residue was
puri®ed by column chromatography on silica gel eluted
with hexane/AcOEt (5/1) to give 8 (7.09 g, 36.2 mmol,
1
1
99%) as a pale yellow oil. H NMR (270 MHz, CDCl3) d
oil. H NMR (270 MHz, CDCl3) d 6.30 (1H, dt, Jˆ16.9,
5.70±5.65 (2H, m), 4.09 (2H, br), 2.23 (2H, t, Jˆ7.1 Hz),
2.20±2.11 (2H, m), 1.61 (2H, quintet, Jˆ7.1 Hz), 1.38 (1H,
br), 0.0 (9H, s). 13C NMR (68 MHz, CDCl3) d 131.9, 129.7,
106.9, 84.7, 63.6, 31.0, 27.8, 19.1, 0.0 (£3). IR (neat) 3320,
2275 cm21. EI-MS m/z 196 (M1). HR-MS m/z 196.1297
(Calcd for C11H20OSi: 196.1282).
10.3 Hz), 6.09 (1H, dd, Jˆ15.1, 10.3 Hz), 5.64 (1H, dt,
Jˆ15.1, 7.0 Hz), 5.12 (1H, d, Jˆ16.9 Hz), 4.99 (1H, d,
Jˆ10.3 Hz), 3.76 (3H, s), 2.35 (2H, t, Jˆ7.0 Hz), 2.21
(2H, q, Jˆ7.0 Hz), 1.69 (2H, quintet, Jˆ7.0 Hz). Signals
at 6.09, 5.12 and 4.99 ppm show also small couplings. 13C
NMR (68 MHz, CDCl3) d 154.4, 137.1, 132.9, 132.5, 115.4,
89.5, 73.4, 52.7, 31.6, 27.2, 18.2. IR (neat) 2200, 1700,
1640, 1580 cm21. EI-MS m/z 178 (M1). HR-MS m/z
178.0994 (Calcd for C11H14O2: 178.0993).
3.1.3. (2E)-8-Trimethylsilyloct-2-en-7-ynal (9). To a
Ê
mixture of 8 (1.73 g, 8.83 mmol), molecular sieves 4 A
(4 g) and CH2Cl2 (40 ml) was added NMO (1.35 g,
11.5 mmol), and TPAP (150 mg, 0.427 mmol) at room
temperature. After being stirred for 1.5 h, the reaction
mixture was diluted with ether and ®ltered through a celite
pad. The ®ltrate was concentrated under reduced pressure.
The residue was puri®ed by column chromatography on
silica gel eluted with hexane/AcOEt (15/1) to give 9
3.1.6.
(4RS,5SR,6SR)-4,5-Dihydroxy-2-methoxycar-
bonylbicyclo[4.3.0]non-1-ene (13). A solution of 11
(1.00 g, 5.62 mmol) in toluene (600 ml) was re¯uxed for
2.5 h under an argon atmosphere. The reaction mixture
was cooled to room temperature and concentrated under
reduced pressure to give crude 12 (990 mg, 99%) as a color-
less oil. To a solution of crude 12 (990 mg) in tert-BuOH
(5 ml), H2O (5 ml) and acetone (20 ml) was added NMO
(977 mg, 8.34 mmol) and OsO4 (283 mg, 1.11 mmol) at
1
(1.35 g, 6.96 mmol, 79%) as a pale yellow oil. H NMR
(270 MHz, CDCl3) d 9.52 (1H, d, Jˆ7.8 Hz), 6.86 (1H,
dt, Jˆ15.6, 6.8 Hz), 6.15 (1H, ddt, Jˆ15.6, 7.8, 1.6 Hz),

M. Goto et al. / Tetrahedron58 (2002) 2339±2350
2345
1
2208C under an argon atmosphere. After being stirred for
30 min, the reaction mixture was quenched with saturated
aqueous Na2SO3 and extracted with AcOEt. The extract was
washed with brine, dried over MgSO4 and concentrated
under reduced pressure. The residue was puri®ed by column
chromatography with silica gel eluted with hexane/AcOEt
(2/1) to give 13 (691 mg, 3.26 mmol, 58% from 11) as white
prisms. Mp 150±1518C (benzene). H NMR (270 MHz,
CDCl3) d 7.86 (2H, d, Jˆ8.8 Hz), 7.79 (2H, d, Jˆ8.6 Hz),
7.59 (2H, d, Jˆ8.6 Hz), 7.52 (2H, d, Jˆ8.8 Hz), 5.88±5.80
(1H, m), 5.11 (1H, dd, Jˆ10.5, 2.4 Hz), 3.75 (3H, s),
3.16±2.73 (5H, m), 2.21±2.07 (1H, m), 1.79±1.56 (1H,
m), 1.44±1.24 (1H, m). 13C NMR (68 MHz, CDCl3) d
166.9, 165.2, 165.0, 157.7, 131.8, 131.7, 131.1 (£2),
129.0, 128.7, 128.3 (£2), 117.4, 75.2, 69.2, 51.4, 43.7,
32.7, 32.3, 30.7, 23.8. IR (CHCl3) 1721, 1657 cm21
.
1
crystals. Mp 131.5±132.58C (EtOH). H NMR (270 MHz,
CDCl3) d 4.12±4.06 (1H, m), 3.99±3.87 (1H, m), 3.71 (3H,
s), 2.92±2.50 (4H, m), 2.39±2.23 (1H, m), 2.00±1.80 (2H,
m), 1.99 (1H, d, Jˆ6.8 Hz), 1.87 (1H, d, Jˆ6.4 Hz), 1.75±
1.53 (2H, m). 13C NMR (68 MHz, CDCl3) d 167.3, 157.0,
118.1, 70.1, 69.2, 51.2, 49.0, 32.2, 30.3, 26.7, 24.2. IR
(CHCl3) 3400, 1700, 1660 cm21. EI-MS m/z 212 (M1).
HR-MS m/z 212.1029 (Calcd for C11H16O4: 212.1048).
Anal. Calcd for C11H16O4: C, 62.25; H, 7.60. Found: C,
62.20; H, 7.68.
EI-MS m/z 547 (M12OMe). Anal. Calcd for C25H22
Br2O6: C, 51.93; H, 3.83. Found: C, 52.08; H, 3.86. Crystal
Ê
data, Mˆ578.25; monoclinic; P21/c(#14); aˆ11.491(2) A,
Ê
Ê
Ê 3
bˆ17.496(2) A, cˆ11.981(2) A, Vˆ2403.6(6) A ; Zˆ4;
m(Mo Ka)ˆ34.21 cm21; F000ˆ1160.00; Dcˆ1.598 g/cm3;
crystal dimensions: 0.20£0.20£0.20 mm3. A total of 5978
re¯ections were collected using the v ±2u scan technique to
a maximum 2u value of 558, and 2803 re¯ections with
I.3.00s(I) were used in the structure determination. Final
R and Rw values were 0.052 and 0.097, respectively. The
maximum and minimum peaks in the difference map were
3.1.7.
(4SR,5RS,6SR)-4,5-Dihydroxy-2-methoxycar-
bonylbicyclo[4.3.0]non-1-ene (14). Crude 12 (645 mg),
which was obtained from 11 (650 mg, 3.65 mmol), was
solvated in AcOH (20 ml). To the solution was added I2
(974 mg, 3.83 mmol) and AgOAc (1.37 g, 8.21 mmol) at
room temperature. After being stirred for 3 h, aqueous
AcOH (H2O/AcOH 1/25, 6 ml) was added to the reaction
mixture. After being re¯uxed for 2 h, NaCl (2 g) was added
to the reaction mixture at 08C and the resulting mixture was
®ltered. The ®ltrate was concentrated under reduced
pressure. The residue was solvated in methanol and 10%
KOH (10 ml) was added to the resulting mixture. After
24 h, since the reaction did not proceed completely, KOH
(2.0 g, 35.7 mmol) was added to the mixture. After 10 min,
the mixture was concentrated under reduced pressure and
extracted with AcOEt. The extract was washed with brine,
dried over MgSO4 and concentrated under reduced pressure.
The residue was puri®ed by column chromatography on
silica gel eluted with hexane/AcOEt (1/1) to give 14
(370 mg, 1.75 mmol, 48%, from 11) as white crystals. Mp
101±1028C (AcOEt/CHCl3). 1H NMR (270 MHz, CDCl3) d
4.16 (1H, dd, Jˆ5.9, 2.4 Hz), 3.72 (3H, s), 3.49 (1H, dd,
Jˆ9.8, 2.4 Hz), 2.98±2.58 (5H, m), 2.30±2.17 (3H, m),
1.99±1.85 (1H, m), 1.72±1.50 (1H, m), 1.33±1.14 (1H,
m). 13C NMR (68 MHz, CDCl3) d 167.5, 158.1, 117.1,
74.5, 68.8, 51.2, 45.2, 34.1, 32.8, 30.5, 23.9. IR (CHCl3)
3450, 1702, 1653 cm21. EI-MS m/z 212 (M1), 194, 135.
HR-MS m/z 212.1058 (Calcd for C11H16O4: 212.1048).
Anal. Calcd for C11H16O4: C, 62.25; H, 7.60. Found: C,
62.51; H, 7.79.
2
Ê 3
0.37 and 20.39 e /A , respectively.
3.1.9. (4RS,5SR,6SR)-4,5-Isopropylidenedioxy-2-meth-
oxycarbonylbicyclo[4.3.0]non-1-ene (16). To a solution
of 13 (123 mg, 0.580 mmol) in dry acetone (4 ml) was
added 2,2-dimethoxypropane (0.36 ml, 2.96 mmol) and
PPTS (30 mg, 0.119 mmol) under an argon atmosphere at
room temperature. After being stirred for 3 h, the reaction
mixture was quenched with triethylamine (0.1 ml) and the
solvent was removed under reduced pressure. The residue
was extracted with ether. The extract was washed with brine
and dried over MgSO4. The solvent was removed under
reduced pressure. The residue was puri®ed by column chro-
matography with silica gel eluted with hexane/AcOEt (10/1)
to give 16 (123 mg, 0.488 mmol, 84%) as a colorless oil. 1H
NMR (270 MHz, CDCl3) d 4.60 (1H, ddd, Jˆ7.3, 3.4,
1.9 Hz), 4.52 (1H, dd, Jˆ7.3, 4.2 Hz), 3.74 (3H, s), 3.05
(1H, dd, Jˆ15.9, 1.9 Hz), 3.02±2.87 (1H, m), 2.70±2.51
(1H, m), 2.28±2.16 (1H, m), 2.01±1.77 (4H, m), 1.71±
1.52 (1H, m), 1.29 (3H, s), 1.24 (3H, s). 13C NMR
(68 MHz, CDCl3) d 167.3, 161.6, 118.4, 107.8, 75.5, 74.9,
51.1, 45.7, 33.8, 28.9, 26.9, 26.2, 26.0, 24.2. IR (neat) 1700,
1640 cm21. EI-MS m/z 252 (M1). HR-MS m/z 252.1337
(Calcd for C14H20O4: 252.1360).
3.1.10. (4RS,5SR,6SR)-2-Hydroxymethyl-4,5-isopropyl-
idenedioxybicyclo[4.3.0]non-1-ene (17). To a solution of
16 (97.5 mg, 0.387 mmol) in toluene (3 ml) was added
dropwise DIBAH (1.02 M in toluene, 0.85 ml,
0.867 mmol) under an argon atmosphere at 2788C. After
being stirred for 30 min, the reaction mixture was quenched
with saturated aqueous NH4Cl and extracted with ether. The
extract was washed with brine, dried over MgSO4 and
concentrated under reduced pressure. The residue was puri-
®ed by column chromatography with silica gel eluted with
hexane/AcOEt (1/1) to give 17 (74.9 mg, 0.334 mmol, 86%)
as white crystals. Mp 89.5±90.58C (EtOH). 1H NMR
(270 MHz, CDCl3) d 4.55 (1H, ddd, Jˆ7.3, 2.9, 2.0 Hz),
4.49 (1H, dd, Jˆ7.3, 3.9 Hz), 4.18 (1H, br d, Jˆ9.0 Hz),
4.02 (1H, br d, Jˆ9.0 Hz), 2.50 (1H, dd, Jˆ15.4, 2.0 Hz),
2.32 (2H, br), 2.13 (1H, br), 2.00±1.75 (4H, m), 1.71±1.44
(2H, m), 1.30 (3H, s), 1.28 (3H, s). 13C NMR (68 MHz,
CDCl3) d 141.9, 124.7, 107.5, 76.5, 75.0, 63.0, 42.4, 30.6,
3.1.8.
methoxycarbonylbicyclo[4.3.0]non-1-ene (15). To
(4RS,5SR,6RS)-4,5-Di(4-bromobenzoyloxy)-2-
a
solution of 14 (38.9 mg, 0.183 mmol) in pyridine (1 ml)
was added p-bromobenzoyl chloride (242 mg, 1.10 mmol)
and dimethylaminopyridine (DMAP, 134 mg, 1.10 mmol)
at room temperature under an argon atmosphere. After
being stirred for 1.5 h, the reaction mixture was quenched
with 5% HCl at 08C and extracted with ether. The extract
was washed with brine and saturated aqueous NaHCO3,
dried over MgSO4, and concentrated under reduced
pressure. The residue was puri®ed by column chromato-
graphy with silica gel eluted with hexane/AcOEt (10/1) to
give 15 (82.2 mg, 0.142 mmol, 78%) as a white solid.
Recrystallization from benzene afforded 15 as colorless

2346
M. Goto et al. / Tetrahedron58 (2002) 2339±2350
29.2, 27.4, 26.4, 25.9, 24.2. IR (CHCl3) 3450, 1680 cm21
.
(132 mg, 0.550 mmol) was converted into 21 (146 mg,
76%) as a colorless oil. H NMR (270 MHz, CDCl3) d
1
EI-MS m/z: 224 (M1). HR-MS m/z 224.1384 (Calcd for
C13H20O3: 224.1411). Anal. Calcd for C13H20O3: C, 69.61;
H, 8.99. Found: C, 69.58; H, 9.24.
8.41 (1H, br s), 7.70 (1H, br s), 7.05 (1H, br s), 4.95 (1H,
dd, Jˆ11.7, 1.5 Hz), 4.51 (1H, br d, Jˆ11.7 Hz), 4.48±4.44
(1H, m), 4.41±4.34 (1H, m), 2.57 (1H, br d, Jˆ15.6 Hz),
2.14±1.70 (8H, m), 1.40 (3H, s), 1.30 (3H, s). 13C NMR
(68 MHz, CDCl3) d 184.1, 136.9, 130.8, 118.0, 107.0,
76.4, 75.1, 73.9, 70.3, 58.2, 43.3, 31.9, 30.4, 26.7, 26.3,
25.7, 23.2. IR (neat) 1200, 980 cm21. EI-MS m/z 350
(M1), 335, 223. HR-MS m/z 350.1326 (Calcd for
C17H22O4N2S: 350.1299).
3.1.11. (1RS,2RS,4RS,5SR,6RS)-1,2-Epoxy-2-hydroxy-
methyl-4,5-isopropylidenedioxybicyclo[4.3.0]nonane (18)
and
(1SR,2SR,4RS,5SR,6RS)-1,2-epoxy-2-hydroxy-
methyl-4,5-isopropylidenedioxybicyclo[4.3.0]nonane (19).
To a solution of 17 (90.0 mg, 0.402 mmol) in CH2Cl2
(12 ml) was added m-CPBA (70%, 148 mg, 0.600 mmol)
under an argon atmosphere at 2208C. After being stirred
for 2.5 h, the reaction mixture was warmed to 258C, then
quenched with saturated aqueous Na2SO3 and extracted
with CH2Cl2. The extract was washed with brine and dried
over MgSO4. The residue was puri®ed by column chromato-
graphy with silica gel eluted with hexane/AcOEt (1/1) to
give 18 (49.6 mg, 0.207 mmol, 52%) as white crystals and
19 (20.8 mg, 0.0867 mmol, 22%) as a colorless oil. 18: mp
76.0±77.08C (AcOEt/hexane). 1H NMR (270 MHz, CDCl3)
d 4.45±4.36 (2H, m), 3.78±3.65 (2H, m), 2.44 (1H, d,
Jˆ15.8 Hz), 2.20±1.50 (9H, m), 1.51 (3H, s), 1.27 (3H,
s). 13C NMR (68 MHz, CDCl3) d 108.0, 71.7, 71.5, 69.0,
64.4, 61.4, 41.5, 28.4, 27.8, 26.4, 25.9, 23.4, 22.6. IR
(CHCl3) 3300 cm21. EI-MS m/z 240 (M1). HR-MS m/z
240.1348 (Calcd for C13H20O4: 240.1360). Anal. Calcd for
C13H20O4: C, 64.98; H, 8.39. Found: C, 64.65; H, 8.50. 19:
1H NMR (270 MHz, CDCl3) d 4.47±4.43 (1H, m), 4.35
(1H, dd, Jˆ7.3, 3.7 Hz), 3.78 (1H, dd, Jˆ11.2, 4.8 Hz),
3.57 (1H, dd, Jˆ11.2, 5.9 Hz), 2.65±2.50 (1H, m), 2.51
(1H, dd, Jˆ15.6, 2.4 Hz), 2.10±1.60 (7H, m), 1.50 (1H,
dd, Jˆ15.6, 3.1 Hz), 1.44 (3H, s), 1.32 (3H, s). 13C NMR
(68 MHz, CDCl3) d 107.1, 75.5, 73.8, 71.2, 64.7, 60.5, 43.4,
3.1.14. (4RS,5SR,6SR)-2-Methoxycarbonyl-4,5-bis(tri-
ethylsilyloxy)bicyclo[4.3.0]non-1-ene (22). To a solution
of 13 (154 mg, 0.726 mmol) and 2,6-lutidine (0.45 ml,
3.86 mmol) in CH2Cl2 (12 ml) was added TESOTf
(0.65 ml, 2.9 mmol) at 2158C under an argon atmosphere.
After being stirred for 10 min, the reaction mixture was
quenched with saturated aqueous NaHCO3 and extracted
with ether. The extract was washed with brine, dried over
MgSO4 and concentrated under reduced pressure. The
residue was puri®ed by column chromatography with silica
gel eluted with hexane/AcOEt (15/1) to give 22 (319 mg,
0.725 mmol, 100%) as a colorless oil. 1H NMR (270 MHz,
CDCl3) d 3.98 (1H, dd, Jˆ2.6, 1.7 Hz), 3.76 (1H, td, Jˆ8.6,
1.7 Hz), 3.73 (3H, s), 2.85±2.35 (5H, m), 1.90±1.45 (4H,
m), 0.97 (9H, t, Jˆ7.4 Hz), 0.93 (9H, t, Jˆ7.4 Hz), 0.62
(12H, q, Jˆ7.4 Hz). 13C NMR (68 MHz, CDCl3) d 167.7,
157.6, 118.5, 71.7, 71.2, 51.0, 50.6, 32.2, 30.7, 27.0, 24.3,
7.0 (£3), 6.9 (£3), 5.2 (£3), 5.0 (£3). IR (neat) 1710,
1660 cm21. EI-MS m/z 440 (M1). HR-MS m/z 440.2793
(Calcd for C23H44O4Si2: 440.2776).
32.6, 30.1, 26.8, 25.9, 25.6, 23.1. IR (neat): 3200 cm21
.
3.1.15. (4RS,5SR,6SR)-2-Hydroxymethyl-4,5-bis(triethyl-
silyloxy)bicyclo[4.3.0]non-1-ene (23). According to the
preparation of 17, 22 (61.9 mg, 0.141 mmol) was converted
into 23 (56.7 mg, 0.138 mmol, 98%) as white crystals. Mp
56.0±57.08C (AcOEt/hexane). 1H NMR (270 MHz, CDCl3)
d 4.04 (2H, br), 3.99±3.95 (1H, m), 3.87±3.77 (1H, m),
2.40±2.08 (5H, m), 1.84±1.45 (5H, m), 0.97 (9H, t,
Jˆ8.1 Hz), 0.93 (9H, t, Jˆ8.1 Hz), 0.68±0.56 (12H, m).
13C NMR (68 MHz, CDCl3) d 137.5, 125.1, 72.2, 71.8,
63.7, 48.0, 31.8, 27.24, 27.16, 24.2, 7.0 (£3), 6.9 (£3), 5.3
(£3), 4.9 (£3). IR (CHCl3) 3550 cm21. EI-MS m/z: 412
(M1). HR-MS m/z: 412.2839 (Calcd for C22H44O3Si2:
412.2827). Anal. Calcd for C22H44O3Si2: C, 64.05; H,
10.75. Found: C, 63.65; H, 10.74.
EI-MS m/z 240 (M1). HR-MS m/z 240.1370 (Calcd for
C13H20O4: 240.1360).
3.1.12. (1RS,2RS,4RS,5SR,6RS)-1,2-Epoxy-2-imidazoyl-
thiocarbonyloxymethyl-4,5-isopropylidenedioxybicyclo-
[4.3.0]nonane (20). To a solution of 18 (49.0 mg,
0.204 mmol) in 1,2-dichloroethane (1.5 ml) was added
1,10-thiocarbonyldiimdazole (90%, 81.0 mg, 0.410 mmol).
After being re¯uxed for 20 min, the reaction was quenched
with saturated aqueous Na2SO3 at room temperature and
extracted with CH2Cl2. Combined extracts were treated
with cold 1 N HCl, washed saturated aqueous NaHCO3,
brine and dried (MgSO4). The solvent was removed under
reduced pressure. The residue was puri®ed by column chro-
matography with silica gel eluted with hexane/AcOEt (2/1)
to give 20 (56.0 mg, 0.160 mmol, 78%) as a colorless oil. 1H
NMR (270 MHz, CDCl3) d 8.36 (1H, br s), 7.65 (1H, t,
Jˆ1.5 Hz), 7.06 (1H, dd, Jˆ1.5, 0.7 Hz), 4.80 (1H, d,
Jˆ12.0 Hz), 4.62 (1H, d, Jˆ12.0 Hz), 4.47±4.37 (2H, m),
2.47 (1H, d, Jˆ15.6 Hz), 2.19±1.57 (8H, m), 1.52 (3H, s),
1.27 (3H, s). 13C NMR (68 MHz, CDCl3) d 183.9, 136.9,
131.0, 117.9, 108.3, 75.1, 71.6, 71.1, 68.6, 58.2, 41.3, 29.1,
3.1.16. (1RS,2RS,4RS,5SR,6RS)-1,2-Epoxy-2-hydroxy-
methyl-4,5-bis(triethylsilyloxy)bicyclo[4.3.0]nonane (24).
To a mixture of 23 (33.6 mg, 81.6 mmol) and NaHCO3
(20.3 mg, 0.242 mmol) in CH2Cl2 (18 ml) was added
m-CPBA (70%, 30.0 mg, 0.122 mmol) under an argon
atmosphere at 2208C. After being stirred for 1 h, the reac-
tion mixture was warmed to room temperature and then was
quenched with saturated aqueous Na2SO3. The mixture was
extracted with CH2Cl2. Combined extracts were washed
with brine and dried (MgSO4). The residue was puri®ed
by column chromatography with silica gel eluted with
hexane/AcOEt (5/1) to give 24 (28.0 mg, 65.4 mmol,
27.6, 26.4, 25.9, 23.5, 22.5. IR (CHCl3) 1280, 1000 cm21
.
EI-MS m/z 350 (M1), 335, 147. HR-MS m/z 350.1328
(Calcd for C17H22O4N2S: 350.1299).
1
3.1.13. (1SR,2SR,4RS,5SR,6RS)-1,2-Epoxy-2-imidazoyl-
thiocarbonyloxymethyl-4,5-isopropylidenedioxybicyclo-
[4.3.0]nonane (21). According to the preparation of 20, 19
80%) as a colorless oil. H NMR (270 MHz, CDCl3) d
3.91 (2H, br, Jˆ2.1 Hz), 3.70±3.60 (3H, m), 2.10 (1H, dd,
Jˆ14.5, 10.8 Hz), 2.02±1.50 (8H, m), 0.96 (18H, t,

M. Goto et al. / Tetrahedron58 (2002) 2339±2350
2347
Jˆ8.0 Hz), 0.61 (12H, q, Jˆ8.0 Hz). 13C NMR (68 MHz,
CDCl3) d 71.7, 71.6, 71.4, 65.1, 62.1, 45.6, 31.9, 27.8, 23.7,
21.0, 7.0 (£3), 6.8 (£3), 5.1 (£3), 4.8 (£3). IR (neat)
3400 cm21. EI-MS m/z 428 (M1). HR-MS m/z 428.2798
(Calcd for C22H44O4Si2: 428.2776).
62.1, 43.3, 34.3, 32.4, 31.6, 24.4, 7.4 (£6), 5.5 (£6). IR
(neat) 3450 cm21. EI-MS m/z 428 (M1), 399, 381.
HR-MS m/z 428.2752 (Calcd for C22H44O4Si2:428.2776).
3.1.21. (1RS,2RS,4RS,5SR,6SR)-1,2-Epoxy-2-imidazolyl-
thiocarbonyloxymethyl-4,5-bis(triethylsilyloxy)bicyclo-
[4.3.0]nonane (29). According to the preparation of 20, 28
(500 mg, 1.17 mmol) was converted into 29 (605 mg,
3.1.17. (1RS,2RS,4RS,5SR,6RS)-1,2-Epoxy-2-imidazolyl-
thiocarbonyloxymethyl-4,5-bis(triethylsilyloxy)bicyclo-
[4.3.0]nonane (25). According to the preparation of 20, 24
(116 mg, 0.271 mmol) was converted into 25 (122 mg,
1
1.12 mmol, 96%) as a colorless oil. H NMR (270 MHz,
CDCl3) d 8.34 (1H, br), 7.63 (1H, t, Jˆ1.7 Hz), 7.07 (1H,
dd, Jˆ1.7, 1.0 Hz), 4.71 (1H, d, Jˆ11.7 Hz), 4.46 (1H, d,
Jˆ11.7 Hz), 3.90±3.83 (1H, m), 3.33 (1H, dd, Jˆ9.8,
2.0 Hz), 2.58±2.45 (1H, m), 2.31 (1H, dd, Jˆ15.8,
3.0 Hz), 2.28±2.15 (1H, m), 1.93 (1H, dd, Jˆ15.8,
4.2 Hz) 1.95±1.58 (4H, m), 1.38±1.16 (1H, m), 0.97
(18H, t, Jˆ7.8 Hz), 0.67±0.54 (12H, m). 13C NMR
(68 MHz, CDCl3) d 183.9, 136.7, 131.0, 117.8, 76.5, 76.1,
70.7, 69.9, 58.5, 42.5, 34.1, 32.0, 31.1, 24.0, 6.94 (£3), 6.88
(£3), 5.1 (£6). IR (neat) 1232, 998 cm21. EI-MS m/z 509
(M1-Et). HR-MS m/z 509.2338 (Calcd for C24H41N2O4SSi2:
509.2323).
1
0.228 mmol, 84%) as a colorless oil. H NMR (270 MHz,
CDCl3) d 8.36 (1H, br s), 7.65 (1H, t, Jˆ1.4 Hz), 7.06 (1H,
br), 4.81 (1H, d, Jˆ11.7 Hz), 4.53 (1H, d, Jˆ11.7 Hz), 3.94
(1H, br), 3.69 (1H, ddd, Jˆ10.7, 6.8, 2.2 Hz), 2.21 (1H, dd,
Jˆ14.4, 10.7 Hz), 2.10±1.50 (8H, m), 0.96 (9H, t,
Jˆ8.1 Hz), 0.95 (9H, t, Jˆ7.6 Hz) 0.66±0.54 (12H, m).
13C NMR (68 MHz, CDCl3) d 184.0, 136.8, 130.9, 117.8,
76.1, 71.4, 71.1, 58.6, 53.3, 45.3, 31.8, 27.7, 23.7, 20.8, 6.9
(£3), 6.6 (£3), 5.1 (£3), 4.7 (£3). IR (neat) 1280,
1000 cm21. EI-MS m/z 538 (M1), 509, 480, 382. HR-MS
m/z 538.2712 (Calcd for C26H46 N2O4SSi2: 538.2714).
3.1.18. (4RS,5SR,6RS)-2-Methoxycarbonyl-4,5-bis(tri-
ethylsilyloxy)bicyclo[4.3.0]non-1-ene (26). According to
the preparation of 22, 14 (240 mg, 1.13 mmol) was
converted into 26 (493 mg, 1.12 mmol, 99%) as a colorless
3.1.22.
2-Hydroxymethylbicyclo[4.3.0]nona-1,4-diene
(30). DIBAH reduction of the crude 12, which was prepared
by Diels±Alder reaction of 11 (586 mg, 3.29 mmol), was
carried out according to the preparation of 17 to give 30
1
1
oil. H NMR (270 MHz, CDCl3) d 4.01 (1H, dd, Jˆ2.9,
(429 mg, 2.86 mmol, 87% from 11) as a wax. H NMR
2.0 Hz), 3.70 (3H, s), 3.39 (1H, dd, Jˆ9.8, 2.0 Hz),
2.96±2.55 (3H, m), 2.51±2.45 (2H, m), 2.18±2.06 (1H,
m), 1.91±1.78 (1H, m), 1.67±1.44 (1H, m), 1.22±1.00
(1H, m), 1.00±0.90 (18H, m), 0.65±0.46 (12H, m). 13C
NMR (68 MHz, CDCl3) d 167.9, 159.8, 116.9, 75.8, 70.7,
51.0, 45.6, 36.3, 33.0, 31.1, 23.8, 6.9 (£3), 6.8 (£3), 6.4
(£3), 5.0 (£3). IR (neat) 1719, 1655 cm21. EI-MS m/z 440
(M1), 411. HR-MS m/z 440.2792 (Calcd for C23H44O4Si2:
440.2776).
(270 MHz, CDCl3) d 5.87±5.74 (2H, m), 4.11 (2H, s),
2.96±2.86 (1H, m), 2.72 (2H, br), 2.36 (2H, br t,
Jˆ7.5 Hz), 2.16±1.96 (2H, m), 1.85±1.56 (2H, m), 1.26±
1.07 (1H, m). 13C NMR (68 MHz, CDCl3) d 139.5, 128.0,
125.1, 124.5, 63.2, 41.6, 32.3, 28.4, 26.6, 23.1. IR (neat)
3300, 1640 cm21. EI-MS m/z 149 (M12H), 130. HR-MS
m/z 149.0946 (Calcd for C10H13O: 149.0966).
3.1.23. 1,2-Epoxy-2-hydroxymethylbicyclo[4.3.0]non-4-
enes (31 and 32). According to the epoxidation of 23, 30
(1.20 g, 8.00 mmol) was converted into 31 (340 mg,
2.05 mmol, 26%, more polar) and 32 (194 mg, 1.17 mmol,
3.1.19. (4RS,5SR,6RS)-2-Hydroxymethyl-4,5-bis(triethyl-
silyloxy)bicyclo[4.3.0]non-1-ene (27). According to the
preparation of 17, 26 (719 mg, 1.63 mmol) was converted
into 27 (618 mg, 1.50 mmol, 92%) as white crystals. Mp
68.0±69.08C (AcOEt/hexane). 1H NMR (270 MHz,
CDCl3) d 4.15±3.96 (3H, m), 3.36 (1H, dd, Jˆ9.9,
2.0 Hz), 2.59 (1H, br), 2.47±2.17 (5H, m), 2.13±2.01 (1H,
m), 1.83±1.73 (1H, m), 1.64±1.43 (1H, m), 1.17±1.01 (1H,
m), 1.00±0.92 (18H, m), 0.61 (12H, q, Jˆ8.4 Hz). 13C NMR
(68 MHz, CDCl3) d 139.7, 123.2, 76.5, 71.3, 63.6, 43.3,
37.1, 31.7, 28.0, 23.7, 7.0 (£6), 5.1 (£6). IR (CHCl3)
3454 cm21. EI-MS m/z 412 (M1), 383. HR-MS m/z
412.2805 (Calcd for C22H44O3Si2: 412.2827). Anal. Calcd
for C22H44O3Si2: C, 64.05; H, 10.75. Found: C, 63.75; H,
11.19.
1
15%, less polar) as colorless oils. 31: H NMR (270 MHz,
CDCl3) d 5.55 (1H, br d, Jˆ10.2 Hz), 5.49±5.40 (1H, m),
3.77 (1H, dd, Jˆ12.1, 6.1 Hz), 3.68 (1H, dd, Jˆ12.1,
4.4 Hz), 2.73±2.54 (2H, m), 2.46±2.29 (2H, m), 2.12±
1.82 (3H, m), 1.75±1.58 (2H, m), 1.55±1.40 (1H, m). 13C
NMR (68 MHz, CDCl3) d 125.7, 122.9, 72.9, 64.4, 53.3,
41.1, 27.7, 27.3, 26.9, 20.7. IR (neat) 3450 cm21. EI-MS
m/z 166 (M1), 83. HR-MS m/z 166.1010 (Calcd for
1
C10H14O2: 166.0993). 32: H NMR (270 MHz, CDCl3) d
5.66±5.57 (1H, m), 5.54±5.44 (1H, m), 3.69 (2H, d,
Jˆ5.4 Hz), 2.69±2.55 (1H, m), 2.52±2.46 (2H, m), 2.33
(1H, t, Jˆ5.7 Hz), 2.14±1.75 (5H, m), 1.37±1.18 (1H, m).
13C NMR (CDCl3) d 125.4, 121.4, 69.9, 64.7, 61.9, 41.1,
31.5, 27.3, 27.1, 23.4. IR (CHCl3): 3400, 1660 cm21. EI-MS
m/z 166 (M1), 83. HR-MS m/z 166.0992 (Calcd for
C10H14O2: 166.0993).
3.1.20. (1RS,2RS,4RS,5SR,6SR)-1,2-Epoxy-2-hydroxy-
methyl-4,5-bis(triethylsilyloxy)bicyclo[4.3.0]nonane (28).
According to the preparation of 24, 27 (618 mg,
1.50 mmol) was converted into 28 (624 mg, 1.46 mmol,
3.1.24. Imidazolylthiocarbonylation of 31. According to
the preparation of 20, 31 (91.9 mg, 0.554 mmol) was
converted into 33 (112 mg, 0.406 mmol, 73%) as a colorless
oil. 1H NMR (270 MHz, CDCl3) d 8.37 (1H, s), 7.64 (1H, br
s), 7.05 (1H, br s), 5.64 (1H, br d, Jˆ10.2 Hz), 5.56±5.45
(1H, m), 4.99 (1H, d, Jˆ11.7 Hz), 4.65 (1H, d, Jˆ11.7 Hz),
2.71 (1H, dd, Jˆ16.1, 5.9 Hz), 2.60±2.42 (2H, m),
1
97%) as a colorless oil. H NMR (270 MHz, CDCl3) d
3.87±3.80 (1H, m), 3.58 (2H, br), 3.30 (1H, dd, Jˆ9.5,
2.0 Hz), 2.52±2.38 (1H, m), 2.22 (1H, dd, Jˆ15.8,
2.0 Hz), 2.21±2.08 (1H, m), 1.98±1.58 (6H, m), 1.33±
1.15 (1H, m), 0.96 (18H, t, Jˆ7.8 Hz), 0.65±0.54 (12H,
m). 13C NMR (68 MHz, CDCl3) d 76.8, 71.6, 70.7, 65.4,

2348
M. Goto et al. / Tetrahedron58 (2002) 2339±2350
2.25±2.10 (1H, m), 2.10±1.90 (2H, m), 1.89±1.69 (2H, m),
1.66±1.47 (1H, m). 13C NMR (68 MHz, CDCl3) d 183.8,
136.7, 130.9, 126.2, 122.2, 117.7, 74.9, 72.3, 60.6, 41.0,
28.4, 27.4, 27.1, 20.8. IR (CHCl3) 1225, 1000 cm21. EI-
MS m/z 276 (M1), 149. HR-MS m/z 276.0914 (Calcd for
C14H16N2O2S: 276.0932).
2.55 (1H, m), 2.45±2.21 (2H, m), 2.10 (1H, br), 1.99±1.77
(5H, m), 0.96 (9H, t, Jˆ8.0 Hz), 0.94 (9H, t, Jˆ8.0 Hz),
0.67±0.56 (12H, m). 13C NMR (68 MHz, CDCl3) d 143.4,
126.0, 74.4, 73.9, 71.5, 66.8, 48.4, 38.4, 31.7, 24.4, 7.0 (£3),
6.8 (£3), 5.3 (£3), 4.8 (£3). IR (CHCl3) 1522 cm21. EI-MS
m/z 381 (M12Et, H2O). HR-MS m/z 381.2282 (Calcd for
C20H37O3Si2: 381.2279).
3.1.25. Imidazolylthiocarbonylation of 32. According to
the preparation of 20, 32 (100 mg, 0.602 mmol) was
converted into 34 (117 mg, 0.424 mmol, 70%) as a colorless
oil. 1H NMR (270 MHz, CDCl3) d 8.35 (1H, br s), 7.64 (1H,
br s), 7.06 (1H, br s), 5.71±5.62 (1H, m), 5.54±5.45 (1H, m),
4.78 (1H, d, Jˆ11.7 Hz), 4.59 (1H, d, Jˆ11.7 Hz),
2.75±2.54 (3H, m), 2.14±2.02 (1H, m), 1.92±1.74 (4H,
m), 1.36±1.32 (1H, m). 13C NMR (68 MHz, CDCl3) d
184.1, 137.1, 131.3, 125.8, 120.9, 118.1, 76.5, 69.8, 58.9,
3.1.28. Thiocarbonylation of 37. According to the prepara-
tion of 36 from 35, 37 (169 mg, 0.395 mmol) was converted
into 38 (158 mg, 85%) as white crystals. Mp 51.0±52.08C
1
(AcOEt/hexane). H NMR (270 MHz, CDCl3) d 5.80 (1H,
br), 4.37 (2H, s), 3.81 (1H, br), 3.54 (1H, ddd, Jˆ12.0, 3.7,
2.0 Hz), 2.64±2.55 (1H, m), 2.54 (1H, t, Jˆ12.0 Hz), 2.49±
2.24 (2H, m), 1.97 (2H, q, Jˆ7.6 Hz), 1.79 (1H, dd, Jˆ12.0,
3.9 Hz), 0.96 (9H, t, Jˆ8.0 Hz), 0.93 (9H, t, Jˆ8.0 Hz), 0.62
(12H, q, Jˆ8.0 Hz). 13C NMR (68 MHz, CDCl3) d 191.2,
136.5, 126.9, 87.8, 78.0, 73.4, 71.1, 47.9, 37.9, 31.9, 24.1,
6.8 (£3), 6.7 (£3), 5.2 (£3), 4.6 (£3). IR (CHCl3) 1230,
990 cm21. EI-MS m/z 470 (M1), 427, 398. HR-MS m/z
470.2313 (Calcd for C23H42O4SSi2: 470.2340). Anal.
Calcd for C23H42O4SSi2: C, 58.70; H, 8.99. Found: C,
58.34; H, 9.07.
41.0, 31.8, 27.6, 27.5, 23.6. IR (neat) 1220, 985 cm21
.
EI-MS m/z 276 (M1), 149, 131. HR-MS m/z 276.0913
(Calcd for C14H16N2O2S: 276.0932).
3.1.26. Conversion of 18 into 36. To a solution of 2,2,6,6-
tetramethylpiperidine (0.22 ml, 1.30 mmol) in benzene
(1.5 ml) was added dropwise n-BuLi (1.63 M in hexane,
0.8 ml, 1.30 mmol) under an argon atmosphere at 08C.
After being stirred for 15 min, a solution of diethyl-
aluminiumchloride (0.95 M in hexane, 1.38 ml,
1.31 mmol) was added dropwise to the mixture at the
3.1.29. (2SR,4RS,5SR,6RS)-2-Hydroxy-2-hydroxymethyl-
4,5-bis(triethylsilyloxy)bicyclo[4.3.0]non-9-ene
(39).
According to the preparation of 37, 28 (124 mg,
0.290 mmol) was converted into 39 (28.6 mg,
same temperature. After 30 min,
a solution of 18
(80.0 mg, 0.333 mmol) in benzene (1.5 ml) was added to
the mixture at the same temperature. After 1 h, the reaction
was quenched with 1 N HCl and was extracted with ether.
The extract was washed with brine, dried over MgSO4 and
concentrated under reduced pressure to give 35, which was
solvated in 1,2-dichloroethane (0.5 ml). To the solution was
added 1,10-thiocarbonyldiimidazole (90%, 25.0 mg,
0.126 mmol). After being re¯uxed for 1 h, the reaction
mixture was quenched with saturated aqueous Na2SO3 at
room temperature and extracted with CH2Cl2. The extract
was treated with cold 1 N HCl, washed with saturated
aqueous NaHCO3 and brine, dried over MgSO4 and concen-
trated under reduced pressure. The residue was puri®ed by
column chromatography with silica gel eluted with hexane/
AcOEt (1/1) to give 36 (10.6 mg, 37.6 mmol, 11% from 18)
0.0668 mmol, 23%) as a
colorless oil. 1H NMR
(270 MHz, CDCl3) d 5.57 (1H, br), 5.16 (1H, s, (OH)),
4.13 (1H, br), 3.82 (1H, d, Jˆ11.0 Hz), 3.58±3.46 (1H,
m), 3.24 (2H, s), 2.40±2.07 (4H, m), 1.69±1.50 (2H, m),
1.47 (1H, dd, Jˆ14.4, 1.7 Hz), 0.99 (9H, t, Jˆ7.6 Hz), 0.97
(9H, t, Jˆ7.6 Hz), 0.73±0.59 (12H, m). 13C NMR (68 MHz,
CDCl3) d 144.9, 123.6, 79.7, 74.4, 70.5, 67.8, 45.3, 38.9,
31.5, 27.8, 7.0 (£3), 6.8 (£3), 5.2 (£3), 4.9 (£3). IR (neat)
3480 cm21. EI-MS m/z 399 (M12Et), 381. HR-MS m/z
399.2384 (Calcd for C20H39O4Si2: 399.2385).
3.1.30. Thiocarbonylation of 39. According to the prepara-
tion of 36, 39 (19.5 mg, 0.0456 mmol) was converted into
40 (8.30 mg, 39%) as a colorless oil. H NMR (270 MHz,
1
CDCl3) d 5.90 (1H, br), 4.77 (1H, d, Jˆ8.9 Hz), 4.20 (1H, d,
Jˆ8.9 Hz), 4.02 (1H, br), 3.39 (1H, m), 3.20 (1H, dd,
Jˆ10.4, 2.5 Hz), 2.43±2.17 (4H, m), 1.71 (1H, dd,
Jˆ15.3, 2.4 Hz), 1.58 (1H, m), 1.00 (9H, t, Jˆ8.4 Hz),
0.97 (9H, t, Jˆ8.4 Hz), 0.77±0.57 (12H, m). 13C NMR
(68 MHz, CDCl3) d 191.5, 140.0, 130.5, 85.5, 78.6, 75.7,
70.9, 44.8, 42.0, 31.3, 28.3, 7.00 (£3), 6.97 (£3), 5.2 (£3),
5.1 (£3). IR (CHCl3) 1218, 1050 cm21. EI-MS m/z 441
1
as a colorless oil. H NMR (benzene-d6) d 5.69 (1H, br),
3.85±3.65 (2H, m), 3.54±3.52 (1H, m), 3.26±3.20 (1H, m),
2.30±1.50 (6H, m), 1.44 (3H, s), 1.16 (3H, s), 1.06±0.88
(1H, m). 13C NMR (benzene-d6) d 191.6, 138.5, 130.4,
109.0, 85.9, 77.8, 75.3, 72.8, 45.0, 36.2, 32.9, 27.0, 25.2,
25.0. IR (CHCl3) 1310, 1120 cm21. EI-MS m/z 282 (M1),
267. HR-MS m/z 282.0933 (Calcd for C14H18O4: 282.0925).
(M12Et).
HR-MS
m/z
441.1948
(Calcd
for
3.1.27. (2SR,4RS,5SR,6SR)-2-Hydroxy-2-hydroxymethyl-
4,5-bis(triethylsilyloxy)bicyclo[4.3.0]non-9-ene (37). To
a solution of 24 (110 mg, 0.257 mmol) in CH2Cl2 (20 ml)
was added p-TsOH´H2O (9 mg) under an argon atmosphere
at 08C. After being stirred for 3 h, the reaction mixture was
quenched with saturated aqueous NaHCO3 and extracted
with CH2Cl2. The extract was washed with brine and dried
over MgSO4. The residue was puri®ed by column chromato-
graphy on silica gel eluted with hexane/AcOEt (10/1) to
give 37 (19.0 mg, 44.4 mmol, 17%) as a colorless oil. H
NMR (270 MHz, CDCl3) d 5.69 (1H, br), 3.78 (1H, br), 3.63
(1H, ddd, Jˆ11.7, 4.4, 2.0 Hz), 3.56±3.42 (2H, m), 2.67±
C21H37O4S1Si2: 441.1950).
3.2. General procedure of radical rearrangement
Under an argon atmosphere, a solution of n-Bu3SnH
(2 equiv.) and AIBN (0.13 equiv.) in benzene or toluene
was added slowly to a re¯uxing solution of substrate in
benzene or toluene by using a syringe pump. After being
re¯uxed for adequate time, the reaction mixture was cooled
to room temperature and the solvent was removed under
reduced pressure. The residue was puri®ed by column
1

M. Goto et al. / Tetrahedron58 (2002) 2339±2350
2349
chromatography on silica gel eluted with hexane/AcOEt to
give bicyclo[5.3.0]decanones and bicyclo[4.3.0]nonanones.
Jˆ7.8 Hz), 0.67±0.54 (12H, m). 13C NMR (68 MHz,
CDCl3) d 214.1, 80.2, 73.6, 50.7, 50.6, 43.9, 38.2, 34.8,
33.0, 25.5, 7.6 (£3), 7.0 (£3), 5.4 (£3), 5.1 (£3). IR (neat)
1696 cm21. EI-MS m/z 383 (M12Et), 280, 217. HR-MS
m/z 383.2415 (Calcd for C20H39O3Si2: 383.2436).
3.2.1.
(1RS,7SR,8SR,9RS)-8,9-Isopropylidenedioxybi-
cyclo[5.3.0]decan-3-one (41). Colorless oil. Compound
41 was obtained as a mixture with an undetected minor
product. The ratio was found to be ca. 4: 1 based on H
1
3.2.6. cis-Bicyclo[5.3.0]decan-8-ene-3-one (46). Colorless
oil. H NMR (270 MHz, CDCl3) d 5.67±5.62 (1H, m),
1
1
NMR. H NMR (500 MHz, CDCl3) d 4.66 (1H, td, Jˆ6.0,
5.53±5.52 (1H, m), 2.84 (1H, br), 2.73±2.22 (6H, m),
2.18±2.00 (1H, m), 1.95±1.75 (2H, m), 1.65±1.50 (2H,
m), 1.43±1.09 (4H, m). 13C NMR (68 MHz, CDCl3) d
213.1, 134.6, 128.6, 48.9, 45.8, 44.5, 39.8, 36.0, 29.1,
22.7. IR (neat) 1700, 1670 cm21. EI-MS m/z 150 (M1),
101. HR-MS m/z 150.1036 (Calcd for C10H14O: 150.1044).
1.0 Hz), 4.58 (1H, t, Jˆ6.0 Hz), 3.15 (1H, t, Jˆ14.0 Hz),
2.55 (1H, ddd, Jˆ15.6, 7.6, 5.5 Hz), 2.43 (1H, ddd, Jˆ15.6,
7.9, 6.1 Hz), 2.31±2.24 (2H, m), 2.14±2.04 (2H, m), 2.03±
1.95 (2H, m), 1.94±1.85 (1H, m), 1.80 (1H, d, Jˆ14.3 Hz),
1.70±1.55 (1H, m), 1.50 (3H, s), 1.305 (3H, s). Observable
signals for minor product: 4.60 (1H, t, Jˆ5.8 Hz), 4.54 (1H,
t, Jˆ5.8 Hz), 2.63 (1H, dd, Jˆ16.5, 2.7 Hz), 2.50 (1H, dd,
Jˆ11.6, 2.5 Hz), 1.45 (3H, s), 1.297 (3H, s). 13C NMR
(68 MHz, CDCl3) d 213.4, 110.0, 83.7, 80.8, 47.2, 45.4,
44.0, 38.8, 37.6, 26.2, 25.0, 23.3, 21.4. IR (neat)
1690 cm21. EI-MS m/z 224 (M1), 209, 149. HR-MS m/z
224.1395 (Calcd for C13H20O3: 224.1411).
3.2.7. (1RS,7SR,8SR,9RS)-8,9-Dihydroxybicyclo[5.3.0]-
decan-3-one (47) (desilylation of 43). To a solution of 43
(4.8 mg, 11.7 mmol) in dry THF (0.1 ml) was added TBAF
(1 M solution in THF, 25 ml, 25 mmol) at 08C under an
argon atmosphere. After being stirred for 2 h, the reaction
mixture was quenched with H2O, extracted with ether,
washed with brine, dried over MgSO4 and concentrated
under reduced pressure. The residue was puri®ed by column
chromatography with silica gel eluted with hexane/AcOEt
(1/10) to give 47 (1.5 mg, 8.15 mmol, 70%) as a colorless
3.2.2.
(1SR,6SR,7SR,8RS)-7,8-Isopropylidenedioxy-1-
1
methylbicyclo[4.3.0]nonan-2-one (42). Colorless oil. H
NMR (270 MHz, benzene-d6) d 4.22 (1H, t, Jˆ6.4 Hz),
4.16 (1H, t, Jˆ6.4 Hz), 3.10 (1H, d, Jˆ13.9 Hz), 2.54±
2.10 (3H, m), 1.74±1.47 (3H, m), 1.43 (3H, s), 1.40±1.32
(1H, m), 1.13 (3H, s), 0.95 (1H, dd, Jˆ14.3, 6.4 Hz), 0.85
(3H, s). 13C NMR (68 MHz, benzene-d6) d 210.8, 111.2,
85.6, 80.3, 54.2, 51.3, 42.2, 37.9, 26.3, 26.2, 25.0, 24.6,
22.4. IR (neat) 1700 cm21. EI-MS m/z 209 (M12Me),
149, 109, 93. HR-MS m/z 209.1149 (Calcd for C12H17O3:
209.1177).
1
oil. H NMR (270 MHz, CDCl3) d 4.10 (1H, ddd, Jˆ10.7,
6.6, 4.1 Hz), 3.94 (1H, t, Jˆ4.1 Hz), 2.70 (1H, dd, Jˆ13.6,
11.7 Hz), 2.62±1.88 (11H, m), 1.60±1.40 (2H, m). 13C
NMR (68 MHz, CDCl3) d 213.2, 77.2, 73.5, 47.3, 44.3,
44.2, 38.6, 33.9, 23.6, 23.2. IR (CHCl3) 1698 cm21
.
EI-MS m/z 184 (M1), 166, 125. HR-MS m/z 184.1068
(Calcd for C10H16O3: 184.1099).
3.2.8. (1RS,7SR,8RS,9SR)-8,9-Dihdroxybicyclo[5.3.0]-
decan-3-one (48) (desilylation of 44). According to the
preparation of 47 from 43, 44 (20.0 mg, 48.5 mmol) was
converted into 48 (7.1 mg, 38.6 mmol, 80%) as a colorless
3.2.3.
(1RS,7SR,8SR,9RS)-8,9-Bis(triethylsilyloxy)bi-
cyclo[5.3.0]decan-3-one (43). Colorless oil. 1H NMR
(270 MHz, CDCl3) d 3.91±3.82 (2H, m), 2.68 (1H, t,
Jˆ13.2 Hz), 2.62±2.50 (1H, m), 2.40±2.13 (3H, m),
2.08±1.70 (5H, m), 1.60±1.35 (2H, m), 0.96 (9H, t,
Jˆ8.3 Hz), 0.95 (9H, t, Jˆ8.3 Hz), 0.68±0.54 (12H, m).
13C NMR (68 MHz, CDCl3) d 213.8, 78.7, 74.7, 48.0,
44.1, 43.9, 38.4, 33.4, 24.2, 23.1, 7.0 (£3), 6.8 (£3), 5.2
(£3), 4.8 (£3). IR (neat) 1700 cm21. EI-MS m/z 412
(M1), 325, 217. HR-MS m/z 412.2856 (Calcd for
C22H44O3Si2: 412.2827).
1
oil. H NMR (270 MHz, CDCl3) d 4.11 (1H, td, Jˆ4.0,
1.5 Hz), 3.74 (1H, dd, Jˆ8.3, 4.0 Hz), 2.75±2.50 (2H, m),
2.47±2.29 (4H, m), 2.20±1.88 (5H, m), 1.68±1.53 (2H, m),
1.42 (1H, ddd, Jˆ13.7, 8.8, 4.0 Hz). 13C NMR (68 MHz,
CDCl3) d 212.8, 79.9, 72.9, 46.4, 46.2, 44.1, 38.1, 33.5,
27.4, 23.2. IR (CHCl3) 1690 cm21. EI-MS m/z 184 (M1),
166. HR-MS m/z 184.1106 (Calcd for C10H16O3: 184.1099).
3.2.9. Conversion of 47 into 41. According to the prepara-
tion of 16 from 13, 47 (7.5 mg, 40.8 mmol) was converted
into 41 (8.2 mg, 36.8 mmol, 90%).
3.2.4.
(1SR,7RS,8SR,9RS)-8,9-Bis(triethylsilyloxy)bi-
cyclo[5.3.0]decan-3-one (44). Colorless oil. 1H NMR
(270 MHz, CDCl3) d 3.98 (1H, br), 3.54 (1H, dd, Jˆ8.8,
3.4 Hz), 2.67±2.49 (2H, m), 2.42±2.10 (3H, m), 2.39 (1H, t,
Jˆ13.7 Hz), 2.03±1.83 (3H, m), 1.63±1.39 (2H, m), 1.30±
1.18 (1H, m), 0.97 (9H, t, Jˆ8.0 Hz), 0.96 (9H, t,
Jˆ7.6 Hz), 0.67±0.55 (12H, m). 13C NMR (68 MHz,
CDCl3) d 213.2, 80.8, 74.5, 46.7, 44.8, 44.2, 38.7, 32.7,
27.2, 23.6, 7.0 (£6), 5.1 (£3), 5.0 (£3). IR (CHCl3)
1700 cm21. EI-MS m/z 383 (M12Et), 251, 217. HR-MS
m/z 383.2413 (Calcd for C20H39O3Si2: 383.2436).
3.2.10. Conversion of 46 into 47. According to the prepara-
tion of 14 from 12, 46 (20.0 mg, 0.133 mmol) was converted
into 47 (7.5 mg, 40.8 mmol, 31%).
3.2.11. Conversion of 46 into 48. According to the prepara-
tion of 13 from 12, 46 (8.4 mg, 56.0 mmol) was converted
into 48 (5.2 mg, 28.3 mmol, 51%).
3.2.5.
(1RS,7RS,8SR,9RS)-8,9-Bis(triethylsilyloxy)bi-
cyclo[5.3.0]decan-3-one (45). Colorless oil. 1H NMR
(270 MHz, CDCl3) d 3.95 (1H, td, Jˆ4.0, 2.2 Hz), 3.43
(1H, dd, Jˆ9.3, 4.0 Hz), 2.64±2.40 (3H, m), 2.37 (1H, dd,
Jˆ17.6, 11.5 Hz), 2.20±1.68 (4H, m), 1.64±1.46 (1H, m),
1.34±1.07 (3H, m), 0.97 (9H, t, Jˆ8.3), 0.96 (9H, t,
Acknowledgements
We thank Dr M. Nakajima and Dr S. Hashimoto of
Hokkaido University (Faculty of Pharmaceutical Sciences)
for measuring X-ray analysis of compound 15. We also

2350
M. Goto et al. / Tetrahedron58 (2002) 2339±2350
5. (a) Nishida, A.; Kakimoto, Y.-I.; Ogasawara, Y.; Kawahara,
N.; Nishida, M.; Takayanagi, H. TetrahedronLett. 1997, 38,
5519. (b) Kakimoto, Y.-I.; Ogasawara, Y.; Nishida, A.;
Kawahara, N.; Nishida, M.; Takayanagi, H. Tetrahedron
2000, 56, 7173.
thank Dr Y. Oshima and Dr M. Ono of Toho University
(School of Pharmaceutical Science) for measuring
500 MHz NMR of 41.
References
È È
6. Witulski, B.; Bergstraûer, U.; Goûmann, M. Tetrahedron
2000, 56, 4747.
1. Wilsey, S.; Dowd, P.; Houk, K. N. J. Org. Chem. 1999, 64,
8801.
7. Smith, W. N.; Kuehn, E. D. J. Org. Chem. 1973, 38, 3588.
8. (a) Brieger, G.; Bennett, J. N. Chem. Rev. 1980, 80, 63.
(b) Oppolzer, W. Angew. Chem., Int. Ed. Engl. 1977, 16, 10.
9. Van Rheenen, V.; Kelly, R. C.; Cha, D. Y. TetrahedronLett.
1976, 23, 1973.
2. (a) Nishida, A.; Takahashi, H.; Takeda, H.; Takada, N.;
Yonemitsu, O. J. Am. Chem. Soc. 1990, 112, 902. (b) Nishida,
A.; Ogasawara, Y.; Kawahara, N.; Nishida, M. Tetrahedron
Lett. 1995, 36, 3015. (c) Nishida, A.; Miyoshi, I.; Ogasawara,
Y.; Nagumo, S.; Kawahara, N.; Nishida, M.; Takayanagi, H.
Tetrahedron 2000, 56, 9241.
10. Woodward, R. B.; Brutcher Jr., F. V. J. Am. Chem. Soc. 1958,
80, 209.
11. (a) RajanBabu, T. V.; Fukunaga, T.; Reddy, G. S. J. Am.
Chem. Soc. 1989, 111, 1759. (b) Crich, D.; Quintero, L.
Chem. Rev. 1989, 89, 1413. (c) Barton, D. H. R.; Crich, D.;
3. The same type of rearrangement was also reported by
Pattenden et al. (a) Ellwood, C. W.; Pattenden, G. Tetrahedron
Lett. 1991, 32, 1591. (b) Mowbray, C. E.; Pattenden, G.
TetrahedronLett. 1993, 34, 127.
È
Lobberding, A.; Zard, S. Z. Tetrahedron 1986, 42, 2329.
12. Yasuda, A.; Yamamoto, H.; Nozaki, H. Bull. Chem. Soc. Jpn
1979, 52, 1705.
4. (a) Corser, D. A.; Marples, B. A.; Dart, R. K. Synlett 1992,
987. (b) Rawal, V. H.; Krishnamurthy, V.; Fabre, A.
TetrahedronLett. 1993, 34, 2899.