gave the cis-triacetate (228 mg, 97%); Rf(EtOAc–light petrol-
THF, 2.5 cm3, 2.5 mmol) was added dropwise to copper() cyan-
eum, 1:5) 0.20; νmax(neat)/cmϪ1 1738 (C᎐O); δ (CDCl ; 250
ide (113 mg, 1.25 mmol) under nitrogen at 0 ЊC and kept for 10
min. The cis-triacetate 24 (542 mg, 1.34 mmol) in dry THF (2.0
cm3) was added dropwise under nitrogen at Ϫ23 ЊC, and kept
for 2 h. Saturated aqueous ammonium chloride (25 cm3) was
added and the mixture extracted with ether (3 × 50 cm3). The
combined organic extracts were washed with saturated aqueous
ammonium chloride (3 × 50 cm3), dried (MgSO4), filtered and
evaporated under reduced pressure. Chromatography (SiO2, 25
g, EtOAc–light petroleum, 1:5) gave the allylsilanes contamin-
ated with dimethyl(phenyl)silanol, which was removed by evap-
oration (60 ЊC at 0.05 mmHg), to leave the allylsilanes (554 mg,
86%) as a 1:1 mixture; Rf(EtOAc–light petroleum, 1:10) 0.25;
᎐
H
3
MHz) 7.32–7.18 (5 H, m, Ph), 6.51 (1 H, d, J 12.8, PhCH᎐CH),
᎐
5.68 (1 H, d, J 12.8, PhCH᎐CH), 4.83 (1 H, dd, J 7.0 and 4.6,
᎐
CHOAc), 3.94 (1 H, dd, J 11.0 and 7.0, CHAHBOAc), 3.85 (1 H,
dd, J 11.0 and 6.1, CHAHBOAc), 2.05–1.64 (4 H, m, CH2CHMe
and CHMe), 2.05 (3 H, s, Ac), 2.04 (3 H, s, Ac), 1.57 (3 H,
MeCO2CMe), 1.53 (3 H, s, MeCO2CMe), 0.98 (3 H, d, J 6.7,
CHMe) and 0.93 (3 H, d, J 7.0, CHMe); m/z 404 (1%, Mϩ),
284 (6, M Ϫ 2 HOAc), 224 (37, M Ϫ 3 HOAc), 209 (20, M Ϫ
3 HOAc Ϫ Me), 171 (40, M Ϫ HOAc Ϫ AcOCHCHMeCH2-
OAc), 147 (100, PhCH᎐CHCMeOH), 131 (34, PhCH᎐CHCO)
᎐
᎐
and 91 (C7H7) (Found: Mϩ, 404.2185. C23H32O6 requires M,
404.2199).
νmax(neat)/cmϪ1 1738 (C᎐O) and 1245 (SiMe Ph); δ (CDCl ;
᎐
2
H
3
250 MHz) 7.36–6.89 (10 H, m, Ph and SiPh), 5.64 (1 H, d,
J 11.7, HC᎐C, one isomer), 5.55 (1 H, d, J 11.3, HC᎐C, one
isomer), 4.86–4.76 (1 H, m, HCOAc), 3.94–3.72 (2 H, m,
CH2OAc), 3.33 (1 H, d, J 11.2, SiCH, one isomer), 3.25 (1 H, d,
J 11.5, SiCH, one isomer), 2.14–1.63 (4 H, m, CH2CHMe and
CHMe), 2.02, 2.00, 1.95, 1.92 (total 6 H, 4 × s, Ac), 1.72 (3 H, s,
(1Z,3R*,5S*,6S*,7S*)-6,8-Dihydroxy-6,8-O-isopropylidene-
3,5,7-trimethyl-1-phenyloct-1-en-3-yl acetate 20
Similarly, the acetate derived from the acetonide 18 gave the cis-
᎐
᎐
alkene; δH(CDCl3) 7.30–7.20 (5 H, m, Ph), 6.39 (1 H, d, J 13,
PhCH᎐CH), 5.72 (1 H, d, J 13, PhCH᎐CH), 3.97 (1 H, dd, J 11
᎐
᎐
and 2, CHAHBO), 3.63–3.23 (2 H, m, CHAHBO and CHO),
2.19–1.56 (4 H, m, CH2CHMe and CHMe), 1.53 (3 H, s, Ac),
1.48 (3 H, s, MeCOAc), 1.33 (3 H, s, CMeAMeB), 1.28 (3 H, s,
CMeAMeB), 1.02 (3 H, d, J 7, CHMe) and 0.86 (3 H, d, J 7,
CHMe).
MeC᎐C, one isomer), 1.44 (3 H, s, MeC᎐C, one isomer), 0.90,
᎐
᎐
0.83, 0.75, 0.66 (total 6 H, 4 × d, J 6.8, 6.8, 6.4 and 6.7, respect-
ively, CHMe), 0.26, 0.24, 0.21 and 0.20 (total 6 H, 4 × s, SiMe2);
δC(CDCl3) 170.7, 170.5, 170.4, 143.2, 142.9, 137.4, 134.3, 133.6,
132.1, 129.0, 128.0, 127.8, 127.5, 125.9, 125.3, 124.5, 124.4,
77.2, 66.6, 43.6, 38.0, 37.4, 34.6, 34.2, 34.0, 33.6, 32.9, 24.6,
20.7, 16.2, 15.8, 10.9, 10.8, Ϫ4.0, Ϫ4.3, Ϫ4.6 and Ϫ4.7; m/z 480
(1 %, Mϩ), 286 (5, M Ϫ SiMe2Ph Ϫ OAc), 226 (6, M Ϫ SiMe2-
(2R*,3R*,4R*,6R*,7E)-2,4,6-Trimethyl-8-phenyloct-7-ene-
1,3,6-triol
The acetylenic triol (213 mg, 0.77 mol) derived from 19 and
lithium aluminium hydride (150 mg, 3.95 mmol) were refluxed
in dry ether (10 cm3) under nitrogen at 37 ЊC for 5 h. Saturated
aqueous ammonium chloride (5 cm3) was added and the mix-
ture was extracted with ether (3 × 30 cm3). The combined
organic layers were dried (MgSO4), filtered and evaporated
under reduced pressure to give the trans-triol (210 mg, 98%) as
an amorphous solid, mp 117–118 ЊC (from CH2Cl2); νmax(KBr)/
cmϪ1 3600–3150 (O–H); δH(CDCl3; 250 MHz) 7.56–7.21 (5 H,
PhOAc Ϫ HOAc), 184 (14), 171 (12), 145 (28, PhCH᎐
᎐
CHCMe ), 144 (90, PhCH᎐CHMeC᎐CH ), 135 (40, SiMe Ph),
᎐
᎐
2
2
2
129 (41) and 43 (100, Ac) (Found: Mϩ Ϫ SiMe2PhOAc,
286.1929. C29H40O4Si requires M Ϫ SiMe2PhOAc, 286.1932).
Method B. Dimethyl(phenyl)silyllithium (1.5 cm3 of a 1.0 mol
dmϪ3 in THF, 1.5 mmol) was added dropwise to a stirred sus-
pension of copper() cyanide (68 mg, 0.75 mmol) in dry ether (7
cm3) under nitrogen at 0 ЊC and kept for 10 min. The trans-
triacetate 25 (210 mg, 0.52 mmol) was added and the procedure
described for the epimeric cis-triacetate then gave, after chrom-
atography (SiO2, EtOAc–light petroleum, 1:5), the allylsilanes
26 and 27 (108 mg, 43%, 54% based on reacted starting
material) in a ratio of 2:3 (or 3:2), identical (IR and 1H NMR)
to the earlier sample, and the starting material 25 (42 mg, 20%).
m, Ph), 6.66 (1 H, d, J 17, PhCH᎐CH), 6.36 (1 H, d, J 17,
᎐
PhCH᎐CH), 4.92–4.53 (3 H, br, 3 OH, exchangeable with D O),
᎐
2
3.93–3.40 (3 H, m, CHOH and CH2OH), 2.32–1.52 (3 H, m,
CH2COH and CHMe), 1.37 (3 H, s, MeCOH), 1.33 (1 H,
m, CHMe), 0.96 (3 H, d, J 7, CHMe) and 0.88 (3 H, d, J 6,
CHMe); m/z 260 (35%, M Ϫ H2O), 245 (44, M Ϫ H2O Ϫ Me),
147 [100, PhCH᎐CHC(Me)OH], 131 (84, PhCH᎐CHCO) and
᎐
᎐
(1R*,2E,5R*,6R*,7R*)-6,8-Diacetoxy-3,5,7-trimethyl-1-
dimethyl(phenyl)silyl-1-phenyloct-2-ene 31 and (1R*,2Z,5S*,
6S*,7S*)-6,8-diacetoxy-3,5,7-trimethyl-1-dimethyl(phenyl)-
silyl-1-phenyloct-2-ene 32
91 (48, C7H7) (Found: Mϩ Ϫ H2O, 260.1777. C17H26O3 requires
M Ϫ H2O, 260.1777). This product was contaminated with the
cis-isomer (7%, NMR), which did not separate from it on
recrystallisation.
Method A. The cis-triacetate 30 (503 mg, 1.25 mmol) in dry
THF (2.0 cm3) was treated by method A above to give the
allylsilanes (490 mg, 82%) as a 5:3 or 3:5 mixture; Rf(EtOAc–
(2R*,3R*,4R*,6S*,7E)-2,4,6-Trimethyl-8-phenyloct-7-ene-
1,3,6-triol
Similarly, the acetylenic triol (102 mg, 0.37 mmol) derived from
18 gave the trans-triol (102 mg, 100%) as an amorphous solid,
mp 126.5–127.5 ЊC (from CH2Cl2); νmax(KBr)/cmϪ1 3600–3150
(O–H); δH(CDCl3) 7.67–7.14 (5 H, m, Ph), 6.69 (1 H, d, J 17,
light petroleum, 1:5) 0.44; νmax(neat)/cmϪ1 1738 (C᎐O) and
᎐
1244 (SiMe2Ph); δH(CDCl3; 250 MHz) 7.33–6.90 (10 H, m, Ph
and SiPh), 5.66 (1 H, d, J 11.4, HC᎐C, one isomer), 5.56 (1 H, d,
᎐
J 11.2, HC᎐C, one isomer), 4.84–4.78 (1 H, m, HCOAc), 3.95–
᎐
3.76 (2 H, m, CH2OAc), 3.32 (1 H, d, J 11.1, SiCH, one isomer),
3.28 (1 H, d, J 11.4, SiCH, one isomer), 2.20–1.52 (4 H, m,
CH2CHMe and CHMe), 2.04, 2.04, 2.03, 2.01 (6 H, 4 × s, Ac),
PhCH᎐CH), 6.27 (1 H, d, J 17, PhCH᎐CH), 5.43–4.03 (3 H, br,
᎐
᎐
3 OH, exchangeable with D2O), 3.92–3.48 (3 H, m, CHOH and
CH2OH), 2.22–1.55 (3 H, m, CH2COH and CHMe), 1.37 (1 H,
m, CHMe), 1.36 (3 H, s, MeCOH), 0.85 (3 H, d, J 7, CHMe)
and 0.81 (3 H, d, J 7, CHMe); m/z 260 (21%, M Ϫ H2O), 245
1.67 (3 H, s, MeC᎐C, one isomer), 1.41 (3 H, s, MeC᎐C, one
᎐
᎐
isomer), 0.91, 0.88, 0.70, 0.55 (6 H, 4 × d, J 7.0, 6.8, 6.4 and 6.4,
respectively, CHMe), 0.24, 0.22, 0.21 and 0.20 (6 H, 4 × s,
SiMe2); δC(CDCl3) 170.7, 170.4, 142.9, 134.3, 131.9, 128.9,
128.3, 128.0, 127.4, 126.1, 125.5, 124.4, 77.4, 77.3, 66.5, 42.7,
42.6, 37.8, 34.1, 34.9, 33.1, 32.9, 23.4, 20.7, 15.5, 15.2, 10.7,
Ϫ4.4 and Ϫ4.8; m/z 286 (<1%, M Ϫ SiMe2Ph Ϫ OAc), 226 (4,
(14, M Ϫ H O Ϫ Me), 147 [100, PhCH᎐CHC(Me)OH], 131
᎐
2
(62, PhCH᎐CHCO) and 91 (68, C H ) (Found: Mϩ Ϫ H O,
᎐
7
7
2
260.1771. C17H26O3 requires M Ϫ H2O, 260.1777). This product
was contaminated with the cis-isomer (10%), which did not
separate from it on recrystallisation.
M Ϫ SiMe PhOAc Ϫ HOAc), 145 (14, PhCH᎐CHCMe ), 144
᎐
2
2
(1R*,2E,5S*,6S*,7S*)-6,8-Diacetoxy-3,5,7-trimethyl-1-
dimethyl(phenyl)silyl-1-phenyloct-2-ene 26 and (1R*,2Z,5R*,
6R*,7R*)-6,8-diacetoxy-3,5,7-trimethyl-1-dimethyl(phenyl)-
silyl-1-phenyloct-2-ene 27
(100, PhCH᎐CHMeC᎐CH ), 135 (27, SiMe Ph) and 129 (36)
᎐ ᎐
2 2
(Found: Mϩ Ϫ SiMe2PhOAc, 286.1928. C29H40O4Si requires
M Ϫ SiMe2PhOAc, 286.1932).
Method B. The trans-triacetate 29 (92 mg, 0.23 mmol) was
treated by method B above to give the allylsilanes 31 and 32 (46
Method A. Dimethyl(phenyl)silyllithium (1.0 mol dmϪ3 in
J. Chem. Soc., Perkin Trans. 1, 1998
2659