isomers, (Found: C, 62.0; H, 8.2; Br, 21.4. C19H29BrO2 requires
C, 61.8; H, 7.9; Br, 21.6%); λmax (EtOH)/nm (ε) 274 (16,000);
νmax (CHCl3)/cmϪ1 1661 and 1592; δH (360 MHz, CDCl3) 5.85–
5.76 (1H, m, H2C:CH ), 5.13–5.04 (1H, m, :CH ), 5.03–4.91
(2H, m, :CH2), 4.26–4.14 (2H, m, OCH2), 2.74 (0.5H, dd, J 17.5
and 4.5), 2.69 (0.5H, dd, J 17.5 and 4.5), 2.43 (0.5H, dd, J 17.5
and 3.4), 2.38 (0.5H, dd, J 17.5 and 4.5), 2.32–2.24 (1H, m),
2.12–1.98 (5H, m), 1.92–1.74 (2H, m), 1.69 (1.5H, d, J 1.2,
:CCH3), 1.60 (1.5H, d, J 0.9, :CCHЈ3), 1.42 (3H, t, J 7.0,
OCH2CH3), 1.05 (1.5H, d, J 6.8, CHCH3), 1.02 (1.5H, d, J 6.8,
CHCH3), 0.98 (1.5H, s, CCH3), 0.97 (1.5H, s, CCHЈ3); δC (90
MHz, CDCl3) 195.6 (s), 195.5 (s), 169.6 (s), 169.5 (s), 138.6 (d),
138.6 (d), 135.6 (s), 135.5 (s), 124.4 (d), 123.7 (d), 114.4 (t),
114.3 (t), 102.4 (s), 102.4 (s), 64.7 (t), 48.4 (s), 48.3 (s), 34.4 (t),
34.1 (t), 33.9 (t), 33.8 (t), 32.4 (t), 32.3 (t), 32.0 (d), 31.9 (d), 27.3
(t), 27.1 (t), 26.3 (t), 23.3 (q), 18.6 (q), 18.6 (q), 16.0 (q), 15.1 (q),
14.9 (q), 14.9 (q); m/z (FAB) 369.1441 (Mϩ ϩ H, C19H30BrO2
requires 369.1429).
The organic layer was separated and the aqueous layer was then
extracted with dichloromethane (20 mL). The combined
organic extracts were dried over MgSO4 and then concentrated
in vacuo to leave a yellow oil. The residue was purified by flash
column chromatography on silica using 5% diethyl ether in
petroleum ether as eluent to give the silyl ether (0.66 g, 86%) as
a corresponding mixture of diastereoisomers, as a colourless
oil; data for the mixture of isomers, (Found: C, 73.1; H, 10.7.
C28H48O3Si requires C, 73.0; H, 10.5%); λmax (EtOH)/nm (ε) 202
(10,800), 265 (12,700); νmax (film)/cmϪ1 1640, 1612, 1380, 1239
and 836; δH (360 MHz, CDCl3) 6.15–6.05 (1H, m, H2C:CH ),
5.86–5.78 (1H, m, H2C:CH ), 5.49–5.45 (1H, m, CHOTBS),
5.18–5.08 (2H, m, HC:CH2), 5.05–4.89 (3H, m, :CH and
HC:CH2), 4.11–3.98 (2H, m, OCH2), 2.61–2.54 (1H, m), 2.32–
2.16 (2H, m), 2.10–1.74 (7H, m), 1.71 (0.75H, d, J 1.1, :CCH3),
1.70 (0.75H, d, J 1.1, :CCH3), 1.62 (0.75H, d, J 1.1, :CCH3),
1.60 (0.75H, d, J 1.0, :CCH3), 1.35 (1.5H, t, J 7.1, OCH2CH3),
1.34 (1.5H, t, J 7.0, OCH2CH3), 1.31–1.26 (1H, m), 0.93–0.90
(3H, m, CHCH3), 0.88 (1.5H, 2 × s, CCH3 and CCH3), 0.87
(1.5H, 2 × s, CCH3 and CCH3), 0.86 (4.5H, s, C(CH3)3), 0.85
(4.5H, s, C(CH3)3), 0.03 (3H, s, Si(CH3)2), Ϫ0.04 (1.5H, s,
Si(CHЈ3)2), Ϫ0.05 (1.5H, s, Si(CHЉ3)2); δC (90 MHz, CDCl3)
200.6 (s), 200.5 (s), 200.2 (s), 170.6 (s), 170.4 (s), 170.3 (s), 141.0
(s), 141.0 (s), 140.7 (s), 140.6 (s), 138.8 (d), 138.7 (d), 136.1 (d),
136.1 (d), 136.0 (d), 135.9 (d), 124.1 (d), 124.0 (d), 123.4 (d),
123.3 (d), 119.6 (d), 119.5 (d), 114.4 (t), 114.4 (t), 114.3 (t),
111.7 (t), 67.2 (d), 66.9 (d), 66.8 (d), 63.3 (t), 46.6 (s), 46.5 (s),
46.4 (s), 46.3 (s), 34.4 (t), 34.2 (t), 34.0 (t), 33.9 (t), 33.7 (t), 32.2
(d), 31.8 (d), 31.6 (d), 31.0 (t), 30.9 (t), 27.4 (t), 27.18 (t), 27.15
(t), 26.5 (t), 26.4 (t), 25.9 (q), 23.4 (q), 23.3 (q), 18.4 (q), 18.4 (q),
18.4 (q), 18.1 (s), 16.2 (q), 16.1 (q), 15.4 (q), 15.4 (q), 15.2 (q),
15.2 (q), 15.1 (q), Ϫ4.7 (q), Ϫ4.7 (q), Ϫ4.9 (q), Ϫ5.0 (q); m/z
(CI) 460.3334 (Mϩ, C28H48O3Si requires 460.3373).
5,6-Dimethyl-3-ethoxy-2-(1-hydroxyallyl)-6-((E/Z )-3-methyl-
octa-3,7-dienyl)cyclohex-2-enone 71a
A solution of tert-butyllithium (1.5 M in pentane, 4.0 mL,
6.0 mmol) was added dropwise over 5 minutes to a stirred solu-
tion of a 1 : 1 mixture of the E and Z isomers of the bromide
70 (0.81 g, 2.2 mmol) in THF (44 mL) at Ϫ78 ЊC and the bright
yellow solution was then stirred at Ϫ78 ЊC for 30 minutes.
Acrolein (0.40 mL, 6.0 mmol) was added in one portion and the
resulting pale yellow solution was then stirred at Ϫ78 ЊC for
15 minutes. Water (5 mL) was added and the mixture was then
allowed to warm to room temperature. The mixture was poured
into water (35 mL) and then extracted with ether (2 × 30 mL).
The combined organic extracts were dried over MgSO4 and
then concentrated in vacuo to leave a pale yellow oil. The resi-
due was purified by flash column chromatography on silica
using 0.5% triethylamine and 20–50% diethyl ether in petrol-
eum ether as eluent to give the allylic alcohol (0.58 g, 76%) as an
inseparable 1 : 1 mixture of secondary alcohol epimers and E
and Z isomers, as a colourless oil; data for the mixture of iso-
mers, λmax (EtOH)/nm (ε) 204 (9,800), 266 (13,900); νmax (film)/
cmϪ1 3421, 1638, 1608, 1378 and 1234; δH (360 MHz, CDCl3)
6.09–5.96 (1H, m, H2C:CH ), 5.88–5.80 (1H, m, H2C:CH ),
5.28–5.13 (3H, m, CHOH, :CH and CHOH ), 5.06–4.83 (4H,
m, :CH2 and :CH2), 4.19–4.05 (2H, m, OCH2), 2.68–2.62 (1H,
m), 2.40–2.24 (2H, m), 2.10–1.74 (8H, m), 1.72 (1.5H, 2 × br. s,
:CCH3), 1.63 (1.5H, 2 × br. s, :CCHЈ3), 1.43–1.36 (3H, m,
OCH2CH3), 1.08–1.02 (3H, m, CHCH3), 0.99 (1.5H, 2 × s,
CCH3), 0.95 (1.5H, s, CCH3); δC (90 MHz, CDCl3) 204.8 (s),
204.8 (s), 204.7 (s), 204.7 (s), 169.7 (s), 169.6 (s), 140.2 (d), 140.2
(d), 139.8 (d), 138.8 (d), 138.7 (d), 138.7 (d), 138.6 (d), 135.8 (s),
135.7 (s), 135.6 (s), 135.5 (s), 124.4 (d), 124.3 (d), 123.7 (d),
123.5 (d), 117.0 (s), 116.9 (s), 116.8 (s), 114.4 (t), 114.4 (t), 114.3
(t), 114.3 (t), 112.9 (t), 112.9 (t), 112.8 (t), 68.6 (d), 68.6 (d), 68.4
(d), 63.8 (t), 63.7 (t), 47.1 (s), 46.9 (s), 46.8 (s), 46.7 (s), 34.2 (t),
34.1 (t), 34.1 (t), 33.9 (t), 33.9 (t), 33.6 (t), 33.3 (t), 32.6 (d), 32.5
(d), 31.7 (d), 31.7 (d), 30.4 (t), 27.4 (t), 27.2 (t), 26.6 (t), 26.4 (t),
23.3 (q), 18.4 (q), 18.3 (q), 18.3 (q), 18.2 (q), 16.1 (q), 16.1 (q),
15.3 (q), 15.1 (q); m/z (EI) 328.2407 (Mϩ Ϫ H2O, C22H32O2
requires 328.2402).
(3E,7E )-2-(tert-Butyldimethylsilanyloxy)-14-ethoxy-8,11,12-
trimethylbicyclo[9.3.1]pentadeca-1(14),3,7-trien-15-one 72
A solution of the GrubbsЈ ruthenium pre-catalyst (74 mg, 0.091
mmol) in dichloromethane (5 mL) was added dropwise over
10 hours to a refluxing solution of the diastereoisomeric diene
71b (245 mg, 0.53 mmol) and the ruthenium pre-catalyst
(37 mg, 0.05 mmol) in dichloromethane (180 mL). The mixture
was heated under reflux for a further 5 hours and then allowed
to cool to room temperature. The solvent was removed in vacuo
to leave an orange residue which was purified by flash column
chromatography on silica using 5–10–20% diethyl ether in
petroleum ether as eluent to give: (i) a less polar isomer (48 mg,
22%) (eluted first) as a colourless oil, νmax (film)/cmϪ1 1644,
1614, 1380, 1226 and 833; δH (500 MHz, CDCl3) 5.45 (1H, dd,
J 14.8 and 9.2, CHOTBSC:H ), 5.38 (1H, d, J 9.2, CHOTBS),
5.14 (1H, ddd, J 14.8, 11.2 and 2.6, HC:CHCH2), 4.72–4.70
(1H, m, :CH ), 4.15 (1H, dq, J 9.6 and 7.1, OCH(H)CH3), 3.95
(1H, dq, J 9.6 and 7.1, OC(H)HCH3), 2.50–2.46 (1H, m), 2.39–
2.17 (3H, m), 2.08–2.01 (1H, m), 1.93–1.82 (3H, m), 1.59 (3H,
br. s, :CCH3), 1.37 (3H, t, J 7.1, OCH2CH3), 0.94 (3H, d, J 6.7,
CHCH3), 0.87 (9H, s, SiC(CH3)3), 0.85 (3H, s, CCH3), 0.01 (3H,
s, SiCH3), 0.00 (3H, s, SiCH3); δC (90 MHz, CDCl3) 199.7 (s),
168.9 (s), 135.5 (s), 132.2 (d), 129.2 (d), 124.3 (d), 121.1 (s), 70.3
(d), 63.2 (t), 45.8 (s), 34.7 (t), 31.3 (t), 30.5 (t), 27.7 (t), 26.2 (q),
18.8 (q), 18.3 (s), 15.4 (q), 15.2 (q), 15.1 (q), Ϫ4.6 (q); m/z (FAB)
432.3097 (Mϩ, C26H44O3Si requires 432.3060); and (ii) a more
polar isomer (10 mg, 5%) (eluted second) as a yellow oil, δH (360
MHz, CDCl3) 5.97 (1H, dd, J 15.9 and 7.1, CH(OTBS)C:H ),
5.32 (1H, d, J 7.1, CHOTBS), 5.12 (1H, dt, J 15.9 and 6.6,
HC:CHCH2), 4.75–4.72 (1H, m, :CH ), 4.09–3.99 (2H, m,
OCH2), 2.69 (1H, dd, J 17.5 and 5.0), 2.24 (1H, dd, J 17.5 and
7.3), 2.11–2.06 (3H, m), 2.02–1.90 (3H, m), 1.52 (3H, br. s,
:CCH3), 1.37 (3H, t, J 7.0, OCH2CH3), 0.96 (3H, d, J 6.9,
CHCH3), 0.91 (3H, s, CCH3), 0.85 (9H, s, SiC(CH3)3), 0.02 (3H,
s, SiCH3), Ϫ0.02 (3H, s, SiCH3); δC (90 MHz, CDCl3) 199.4 (s),
2-[1-(tert-Butyldimethylsilanyloxy)allyl]-5,6-dimethyl-3-ethoxy-
6-((E/Z )-3-methylocta-3,7-dienyl)cyclohex-2-enone 71b
tert-Butyldimethylsilyl triflate (0.46 mL, 2.0 mmol) was added
dropwise over 1 minute to a stirred solution of the diastereo-
isomeric allylic alcohol 71a (0.58 g, 1.8 mmol) and diisopropyl-
ethylamine (1.5 mL, 8.6 mmol) in dichloromethane (17 mL) at
0 ЊC and the mixture was then stirred at 0 ЊC for 30 minutes. The
mixture was allowed to warm to room temperature, then
diluted with dichloromethane (23 mL) and poured into a satur-
ated aqueous solution of sodium hydrogencarbonate (40 mL).
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 9 1 7 – 3 9 4 8
3939