O. Roy et al. / Tetrahedron 59 (2003) 5115–5121
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3.1.6. (4S)-2-(tert-Butyldimethylsiloxymethyl)-4-
hydroxy-4-(hydroxymethyl)-1,3,3-trimethyl-cyclohex-1-
ene 10. Lithium aluminium hydride (99 mg, 2.6 mmol) was
added portionwise over 10 min to a solution of the epoxide 9
(270 mg, 0.86 mmol) in ether (20 ml) at 08C. The mixture
was stirred at 08C for 30 min, then carefully quenched with
water (15 ml) and diluted with ether (10 ml). The organic
layer was separated and the aqueous layer was extracted
with ether (2£10 ml). The combined organic extracts were
washed with brine (10 ml), then dried over MgSO4 and
concentrated in vacuo. The residue was purified by
chromatography on silica, eluting with 40% ethyl acetate
in light petroleum to give the diol (260 mg, 96%) which
crystallized from ethyl acetate–light petroleum as colorless
crystals, mp 72–748C. [a]2D3¼þ14.2 (c 0.11 in CHCl3);
(Found: C, 65.3; H, 11.3. C18H32O4Si requires C, 64.9; H,
10.9%); nmax (CHCl3 sol.)/cm21 1462; dH (360 MHz;
CDCl3) 0.08 (s, 6H, Me2Si), 0.90 (s, 9H, tBu), 1.02 (s, 3H,
Me), 1.12 (s, 3H, Me), 1.72 (s, 3H, Me), 1.75–1.85 (m, 2H),
2.03–2.10 (m, 2H), 3.49 (d, J¼11.0 Hz, 1H, CHOH), 3.73
(d, J¼11.0 Hz, 1H, CHOH), 4.11 (s, 2H, CH2OSi); dC
(67.8 MHz; CDCl3) 25.4 (2£q), 18.3 (s), 19.4 (q), 21.7 (q),
22.6 (q), 25.9 (3£q), 26.4 (t), 29.4 (t), 40.7 (s), 58.9 (t), 65.0
(t), 75.0 (s), 131.4 (s), 135.0 (s); m/z (EI) 225.1313
(Mþ2tBu–MeOH. C13H21O2Si requires 225.1311).
room temperature and then ether (15 ml) was added. The
separated organic layer was washed with brine (3£10 ml),
then dried over MgSO4 and concentrated in vacuo. The
residue was purified by chromatography on silica, eluting
with 30% ethyl acetate in light petroleum to give recovered
starting material (61 mg) and a mixture of diastereoisomers
of the alcohol (212 mg, 44%) as a colorless oil. (Found: C,
60.7; H, 9.4. C18H32O5Si requires C, 60.6; H, 9.1%); nmax
(CHCl3 sol.)/cm21 1803, 1668, 1471; (H (360 MHz; CDCl3)
0.09 (s, 3H, Me2Si), 0.10 (s, 3H, Me3Si), 0.91 (s, 9H, tBu),
1.08 (s, 1.5H, Me), 1.79 (s, 3H, Me), 1.27 (s, 1.5H, Me),
1.83 (s, 1.5H, Me), 1.83 (s, 1.5H, Me), 2.07 (dd, J¼13.9,
4.9 Hz, 0.5H), 2.32 (d, J¼4.5 Hz, 1H), 2.51 (dd, J¼13.9,
6.1 Hz, 0.5H), 3.97 (t, J¼4.5 Hz, 0.5H), 4.04 (d, J¼8.8 Hz,
0.5H), 4.12 (d, J¼11.4 Hz, 0.5H), 4.16 (s, 1H), 4.26 (d,
J¼11.4 Hz, 0.5H), 4.32 (t, J¼5.5 Hz, 0.5H), 4.39 (s, 1H),
4.46 (d, J¼8.8 Hz, 0.5H); dC (67.8 MHz; CDCl3) 25.5
(2£q), 16.6 (q), 18.1 (s), 20.6 (q), 22.7 (q), 25.8 (3£q), 37.8 (t),
40.6 (s), 59.1 (t), 68.2 (d), 71.1 (t), 86.9 (s), 132.5 (s), 135.9 (s)
153.2 (s); m/z (EI) 338.1984 (Mþ2H2O. C14H23O4Si
requires M, 338.1913).
3.1.9. (4S)-2-(tert-Butyldimethylsiloxymethyl)-4,6-dihy-
droxy-4-benzoyloxymethyl-1,3,3-trimethyl-cyclohex-1-
ene 13. A solution of phenyllithium (150 ml, 0.27 mmol) in
hexanes–ether (1.8 M) was added dropwise over 10 min to
a stirred solution of the alcohol 12 (98 mg, 0.27 mmol) in
THF (10 ml) at 2788C. The mixture was stirred at 2788C
for 20 min, then quenched with water (2 ml) and allowed to
warm to room temperature over 1 h. The organic layer was
separated and the aqueous layer was extracted with ether
(2£10 ml). The combined organic extracts were dried over
MgSO4 and then concentrated in vacuo. The residue was
purified by chromatography on silica, eluting with 30%
ethyl acetate in light petroleum to give a mixture of
diastereoisomeric diols (101 mg, 86%) as a colorless oil.
(Found: C, 66.0; H, 8.81. C18H32O5Si requires C, 66.3; H,
8.8%); nmax (film)/cm21 1803, 1668, 1471; dH (360 MHz;
CDCl3) 0.10 (s, 6H, Me2Si), 0.91 (s, 9H, tBu), 1.10 (s, 1.5H,
Me), 1.18 (s, 3H, Me), 1.27 (s, 1.5H, Me), 1.86 (s, 1.5H,
Me), 1.90 (s, 1.5H, Me), 1.98 (dd, J¼13.9, 5.6 Hz, 0.5H),
2.11 (dd, J¼14.3, 5.3 Hz, 0.5H), 2.20 (dd, J¼14.3, 3.2 Hz,
0.5H), 2.30 (dd, J¼13.9, 5.4 Hz, 0.5H), 4.00 (m, 0.5H),
4.12–4.32 (m, 3H), 4.44 (d, J¼9.6 Hz, 0.5H), 4.58 (app. t,
J¼11.5 Hz, 1H), 7.43–7.51 (m, 2H), 7.56–7.63 (m, 1H),
8.06–8.10 (m, 2H); dC (67.8 MHz; CDCl3) 25.4 (2£q),
15.2/15.5 (q), 18.2 (s), 21.2/22.1 (q), 22.7/23.5 (q), 26.5
(3£q), 34.9/36.6 (s), 41.6/41.8 (s), 59.0/59.2 (t), 68.4/68.6
(t), 68.8/69.0 (t), 74.4/75.3 (s), 128.1/128.4 (d), 129.5/129.6
(d), 129.8/129.9 (s), 132.4/132.7 (s), 133.1/133.2 (d), 136.7/
137.5 (s), 166.9/167.0 (s); m/z (EI) 338.1984 (Mþ2H2-
O. C18H30O4Si requires M, 338.1913).
3.1.7. (5S)-7-(tert-Butyldimethylsiloxymethyl)-1,3-dioxa-
2-oxo-6,6,8-trimethyl-spiro-[4,5]-dec-7-ene 11. A solution
of phosgene (8.3 mmol) in toluene (4.4 ml, 10%) was added
dropwise over 10 min to a stirred solution of the diol 10
(523 mg, 1.7 mmol) and pyridine (2.2 ml, 26.6 mmol) in
dichloromethane (20 ml) at 2788C. The mixture was stirred
at 2788C for 15 min and then allowed to warm to room
temperature over 2 h, when it was quenched with water
(20 ml) and diluted with dichloromethane (10 ml). The
organic layer was separated and the aqueous layer was
extracted with dichloromethane (2£30 ml). The combined
organic extracts were washed with saturated aqueous
sodium hydrogen carbonate (20 ml) and brine (20 ml),
then dried over MgSO4 and concentrated in vacuo. The
residue was purified by chromatography on silica, eluting
with 30% ethyl acetate in light petroleum to give the
carbonate (552 mg, 98%) which crystallized from ethyl
acetate–light petroleum as colorless crystals, mp 49–518C.
[a]2D4¼220.4 (c 0.225 in CHCl3); (Found: C, 63.9; H, 9.8.
C18H32O4Si requires C, 63.5; H, 9.5%); nmax (CHCl3 sol.)/
cm21 1471; dH (360 MHz; CDCl3) 0.08 (s, 6H, Me2Si), 0.90
(s, 9H, tBu), 1.13 (s, 3H, Me), 1.19 (s, 3H, Me), 1.70 (s, 3H,
Me), 1.86–1.95 (m, 1H), 2.03–2.13 (m, 1H), 2.14–2.23 (m,
1H), 2.27–2.37 (m, 1H), 4.03 (d, J¼8.7 Hz, 1H), 4.09 (d,
J¼11.4 Hz, 1H), 4.18 (d, J¼11.4 Hz, 1H), 4.39 (d,
J¼8.7 Hz, 1H); dC (67.8 MHz; CDCl3) 25.6 (2£q), 17.9
(s), 18.9 (q), 21.3 (q), 22.5 (q), 25.7 (3£q), 28.3 (t), 28.6 (t)
40.1 (s), 58.7 (t), 71.2 (t), 86.7 (s), 130.7 (s), 133.5 (s) 154.7
(s); m/z (EI) 283.1343 (Mþ2tBu. C14H23O4Si requires M,
283.1366).
3.1.10. (5S)-3-(tert-Butyldimethylsiloxymethyl)-5-
hydroxy-5-benzoyloxymethyl-2,4,4-trimethyl-cyclohex-
2-en-1-one 14. A solution of the diol 13 (50 mg, 0.12 mmol)
in dichloromethane (2 ml) was added to a suspension of
pyridinium chlorochromate (37 mg, 0.17 mmol) and sodium
acetate (14 mg, 0.17 mmol) in dichloromethane (5 ml) at
08C. The mixture was stirred at 08C for 3 h, and then
evaporated to small volume (ca. 1 ml) and purified by
chromatography on silica, eluting with 25% ethyl acetate in
light petroleum to give the ketone (47 mg, 95%) as a
3.1.8. (5S)-7-(tert-Butyldimethylsiloxymethyl)-1,3-dioxa-
2-oxo-9-hydroxy-6,6,8-trimethyl-spiro-[4,5]-dec-7-ene
12. Selenium dioxide (150 mg, 1.35 mmol) was added in
one portion to a stirred solution of the carbonate 11 (460 mg,
1.35 mmol) in 1,4-dioxane (10 ml) and the mixture was then
heated at 1008C for 2 h. The mixture was allowed to cool to