736
Can. J. Chem. Vol. 80, 2002
Colourless prism fragment, 0.38{100} × 0.66{010} ×
0.42{001} mm, C13H22O5, M = 258.3, monoclinic, a =
24.4438(17), b = 5.8361(4), c = 17.8409(13) Å, ꢀ =
101.287(4)°, U = 2495.9(4) Å3, T = 180 K, space group
C2/c (No. 15), Z = 8, (Mo Kꢁ) = 0.104 mm–1, 3712 reflec-
tions measured, 3636 unique (Rint = 1.35%), 2974 observed
(F > 6.0ꢂ(F)). The final R and Rw values were 3.08 and
3.87%, respectively (based on F).
2.2 Hz, 1H, H-8ꢀ and H-3ꢀ), 2.32 (m, 2H, H-2), 2.55 (br s,
1H, OH), 2.70 (td, J = 11.8, 2.3 Hz, 1H, H-8a), 3.03 (q, J =
6.3 Hz, 1H, H-9), 3.24 (s, 3H, OMe), 4.15 (d, J = 6.24 Hz,
1H, H-6), 4.29 (dd, J = 6.23, 4.04 Hz, 1H, H-5). 13C NMR
(75 MHz) ꢃ: 11.7, 25.2, 26.3, 26.4, 27.2, 27.7, 41.6, 42.8,
43.9, 57.0, 71.5, 74.1, 81.1 (2 P C), 108.7, 212.2. CI-MS m/z
(%): 299 ([M + 1]+, 28), 241 (20), 239 (31), 209 (12), 181
(33), 163 (12), 135 (11), 59 (100). Anal. calcd. for
C16H26O5: C 64.43, H 8.72; found: C 64.49, H 8.64.
7-(1>-Methoxyethyl)-7ꢀ-hydroxy-5ꢀ,6ꢀ-di-O-isopropyli-
dene-8aꢀ,4aꢁ-octahydro-naphthalen-1-one (19a and 19b)
7-(1>-Methoxyethyl)-7ꢀ-trimethylsiloxy-5ꢀ,6ꢀ-di-O-isopro
pylidene-8aꢀ,4aꢁ-hexahydro-naphthalen-1-one (21a and
21b)
Synthesis of C9-S* isomer 19a
Palladium hydroxide on carbon (100 mg, 20% palladium
by dry weight) was added to the argon-flushed solution of
the acetonide 17a (500 mg, 1.69 mmol), DBU (50 mg, 0.33
mol), CH3ONa (183 mg, 3.4 mmol), CH3OH (128 mL), and
H2O (4 mL). The flask was evacuated and backfilled by H2
three times and then maintained at 1 atm H2 for 4 days. The
resulting solution was then filtered, and the filtrate was neu-
tralized by adding dry ice, then concentrated. The residue
was dissolved in EtOAc and the precipitate was filtered.
EtOAc solution was concentrated in vacuo to give a dark oil
which was chromatographed using EtOAc–hexane–methanol
(1:4:0.5) to give colourless crystals (304 mg, 60%); mp 110–
112°C. IR (KBr) (cm–1): 3527, 2948, 1703, 1435, 1379,
1100, 1030, 881. 1H NMR (500 MHz) ꢃ: 1.11 (d, J = 6.3 Hz,
3H, CH3), 1.36 and 1.52 (s each, 6H, CH3CCH3), 1.47 (dd,
J = 14.9, 12.2 Hz, 1H, H-8ꢁ), 1.61(m, 1H, H-3ꢁ), 1.68 (tt,
J = 12.4, 3.6 Hz, 1H, H-4a), 1.78 (m, 1H, H-4ꢀ), 1.91 (qt,
J W 13.3, 3.8 Hz, 1H, H-4ꢁ), 2.01 (dd, J = 14.5, 2.4 Hz, 1H,
H-8ꢀ), 2.14 (m, 1H, H-3ꢀ), 2.38 (m, 2H, H-2), 2.76 (td, J =
11.9, 2.3 Hz, 1H, H-8a), 2.90 (br s, 1H, OH), 3.02 (q, J =
6.3 Hz, 1H, H-9), 3.34 (s, 3H, OMe), 4.11 (d, J = 6.3 Hz,
1H, H-6), 4.30 (dd, J = 6.3, 3.9 Hz, 1H, H-5). 13C NMR
(75 MHz) ꢃ: 12.5, 25.1, 26.1, 26.4, 27.7, 31.9, 41.7, 42.9,
44.1, 57.2, 71.5, 73.9, 83.4 (2 P C), 108.7, 212.8. CI-MS m/z
(%): 299 ([M + 1]+, 15), 241 (25), 239 (30), 191 (10), 181
(41), 135 (14), 91 (11), 81 (14), 59 (100). Anal. calcd. for
C16H26O5: C 64.43, H 8.72; found: C 64.20, H 8.53.
A fresh LDA solution was prepared from n-BuLi (6.6 mL,
1.36 M in hexane, 9.0 mmol) and diisopropylamine
(1.25 mL, 8.9 mmol) at 0°C in dry THF.
A solution of hydroxy ketone 19 (210 mg, 0.71 mmol) in
dry THF was slowly added to the LDA solution at –78°C
under argon. The mixture was stirred for 1 h at –78°C.
TMSCl (1.8 mL, 14.2 mmol) was then added. The reaction
was stirred for 30 min at –78°C and then allowed to warm to
room temperature. The THF was evaporated under reduced
pressure and the residue was diluted with dry hexane, white
precipitates were filtered, and the hexane solution was con-
centrated in vacuo to give the crude silyl enol ether. The
silyl enol ether was heated at reflux with Pd(OAc)2 (177 mg,
0.78 mmol) in CH3CN (20 mL) for 1 h under argon. The re-
action mixture was filtered through a thin pad of Celite and
the solvent was concentrated in vacuo to give a dark brown
oil. Flash chromatography using 20% EtOAc–hexane of the
crude mixture gave colourless crystals (116 mg, 56%) in
each case.
C9-S* isomer 21a
1H NMR (500 MHz) ꢃ: 0.12 (s, 9H, OSiMe3), 1.21 (d, J =
6.4 Hz, 3H, CH3), 1.31 and 1.51 (s each, 6H, CH3CCH3),
1.52 (dd, J = 14.7, 11.8 Hz, 1H, H-8ꢁ), 2.09 (m, 1H, H-4a),
2.27 (dd, J = 14.8, 3.1 Hz, 1H, H-8ꢀ), 2.33 (dt, J = 19.1,
5.1 Hz, 1H, H-4ꢁ), 2.66 (td, J = 11.8, 2.9 Hz, 1H, H-8a), 2.7
(m, 1H, H-4ꢀ), 3.16 (q, J = 6.4 Hz, 1H, H-9), 3.28 (s, 3H,
OMe), 4.07 (d, J = 5.7 Hz, 1H, H-6), 4.19 (t, J = 5.4 Hz, 1H,
H-5), 5.78 (dd, J = 10, 2.2 Hz, 1H, H-2), 6.97 (ddd, J = 10,
6, 2.2, 1H, H-3). 13C NMR (75 MHz) ꢃ: 2.9 (3 × C), 13.8,
26.0, 26.2, 28.4, 32.0, 39.5, 40.6, 56.7, 74.5, 75.6, 76.6,
104.9, 108.6, 129.1, 149.3, 201.1. EI-MS m/z (%): 309, 251
(17), 161 (12), 131 (19), 89 ([Me3SiO]+, 15), 73 ([Me3Si]+,
100), 59 ([Me-CH=OMe]+, 96). HRMS calcd. for
C16H25O4Si: 309.1522; found: 309.1525 ([M – MeCHOMe]+, 7).
Synthesis of C9-R* isomer 19b
Palladium hydroxide on carbon (120 mg, 20% palladium
by dry weight) was added to the argon flushed solution of
the acetonide 17b (600 mg, 2.03 mmol), DBU (60 mg,
0.4 mmol), CH3ONa (219 mg, 4.1 mmol), CH3OH
(128 mL), and H2O (4 mL). The flask was evacuated and
backfilled with H2 three times and then maintained at 1 atm
for 24 h. The hydrogen source was then turned off and the
reaction was stirred at room temperature for further 3 days.
The resulting solution was then filtered, and the filtrate was
neutralized by adding dry ice, then concentrated. The resi-
due was dissolved in EtOAc (250 mL) and the precipitate
was filtered. EtOAc solution was concentrated in vacuo to
give a dark oil which was chromatographed using EtOAc–
hexane (1:4) to give colourless crystals (420 mg, 70%); mp
140–142°C. IR (KBr): 3516, 2955, 1763, 1443, 1373, 1158,
C9-R* isomer 21b
1H NMR (500 MHz) ꢃ: 0.11 (s, 9H, OSiMe3), 1.1 (dd, J =
14.8, 11.4 Hz, 1H, H-8ꢁ), 1.16 (d, J = 6.3 Hz, 3H, CH3),
1.33 and 1.52 (s each, 6H, CH3CCH3), 2.11 (m, 1H, H-4a),
2.32 (dt, J = 19.1, 5.2 Hz, 1H, H-4ꢁ), 2.61 (td, J = 11.4,
3.4 Hz, 1H, H-8a), 2.65 (m, 1H, H-4ꢀ), 2.68 (dd, J = 14.6,
3.4 Hz, 1H, H-8ꢀ), 3.0 (q, J = 6.3 Hz, 1H, H-9), 3.29 (s, 3H,
OMe), 3.78 (d, J = 5.8 Hz, 1H, H-6), 4.20 (t, J = 5.3 Hz, 1H,
H-5), 5.99 (dd, J = 10, 2.3 Hz, 1H, H-2), 6.97 (ddd, J = 10,
6, 2.1, 1H, H-3). 13C NMR (75 MHz) ꢃ: 3.0 (3 × C), 13.1,
25.5, 26.4, 28.1, 32.0, 39.3, 41.1, 56.3, 75.8, 77.5, 77.8,
78.5, 109.9, 128.3, 148.1, 199.8. EI-MS m/z (%): 353 ([M –
1
1041, 873. H NMR (250 MHz) ꢃ: 1.10 (d, J = 6.3 Hz, 3H,
CH3), 1.18 (dd, J = 14.6, 11.7 Hz, 1H, H-8ꢁ), 1.35 and 1.48
(s each, 6H, CH3CCH3), 1.53 (m, 1H, H-3ꢁ), 1.64 (m, 1H,
H-4a), 1.68–1.97 (m, 2H, H-4), 2.07 (dd and m, J = 14.4,
© 2002 NRC Canada