(4Z,8E,12E,16E)-4-Hydroxymethyl-8,13,17,21-tetramethyl-
docosa-1,4,8,12,16,20-hexaene 17
19-H), 1.87 (m, 2 H, 2-H), 1.68 (s, 3 H, vinyl-CH3), 1.59 (s, 12
H, vinyl-CH3), 0.90 (s, 9 H, SiC(CH3)3) and 0.07 (s, 6 H, SiCH3);
the hydroxy proton was not observed because of broadening of
the signal; δC (125 MHz; CDCl3) 137.7, 135.1, 134.9, 134.6,
131.2, 127.1, 124.7, 124.4, 124.2(×2), 62.5, 60.7, 39.8, 39.7(×2),
31.3, 30.8, 28.2, 27.2, 26.8, 26.6, 26.1, 25.9(×3), 25.6, 18.3, 17.6,
16.0(×2), 15.9 and Ϫ5.3(×2) [Found (HRMS): Mϩ, 516.4340.
C33H60O2Si requires M, 516.4363].
To a solution of (Z)-16 (1.5 g, 3.5 mmol) in Et2O (10 ml) at
Ϫ20 ЊC was added LiAlH4 (0.13 g, 3.5 mmol). After being
stirred for 2 h at 25 ЊC, Et2O and water were added into the
reaction mixture. The resulting mixture was filtered with
suction and the residue was washed with Et2O. The filtrate was
washed with brine, dried over anhydrous MgSO4, filtered, and
concentrated. Purification by column chromatography (silica
gel, EtOAc–hexane, 5:95) gave the alcohol 17 as a colourless oil
(1.3 g, 99%); Rf (EtOAc–hexane, 1:9) 0.27; νmax(neat)/cmϪ1
3360, 2980, 2940, 2870, 1730, 1670, 1640, 1440 and 1380; δH
(500 MHz; CDCl3) 5.83 (ddt, J 17.1, 9.7, 6.7, 1 H, 2-H), 5.33
(t, J 7.3, 1 H, 5-H), 5.17–5.06 (m, 5 H, 1-H, 9-H, 12-H, 16-H,
20-H), 5.04 (dtd, J 9.7, 2.1, 1.0, 1 H, 1-H), 4.13 (s, 2 H,
CH2OH), 2.87 (m, 2 H, 3-H), 2.19 (q, J 7.3, 2 H, 6-H), 2.11–
1.93 (m, 14 H, 7-H, 10-H, 11-H, 14-H, 15-H, 18-H, 19-H), 1.68
(s, 3 H, vinyl-CH3) and 1.60 (s, 12 H, vinyl-CH3), the hydroxy
proton was not observed because of broadening of the signal;
δC (125 MHz; CDCl3) 137.0, 136.7, 135.2, 134.9, 134.4, 131.2,
129.5, 125.0, 124.4, 124.2(×2), 116.0, 60.3, 39.8, 39.7(×2),
28.2(×2), 26.8, 26.7, 26.3, 25.7(×2), 17.7 and 16.0(×3) [Found
(HRMS): Mϩ, 384.3385. C27H44O requires M, 384. 3392].
(4Z,8E,12E,16E)-4-tert-Butyldimethylsilyloxymethyl-
8,13,17,21-tetramethyldocosa-4,8,12,16,20-pentaen-1-al 23
To a mixture of pyridinium chlorochromate (0.18 g, 0.81 mmol)
and Florisil (0.35 g) suspended in CH2Cl2 (10 ml) was added 22
(0.30 g, 0.58 mmol) in CH2Cl2 (2 ml). The mixture was stirred
for 3 h at 25 ЊC. The solid mixture of Florisil and chromium
salts was removed by filtration and the filtrate was concentrated
in vacuo. Purification by column chromatography (silica gel,
EtOAc–hexane, 5:95) gave the aldehyde 23 as a colourless oil
(0.21 g, 72%); Rf (EtOAc–hexane, 1:9) 0.60; νmax(neat)/cmϪ1
2930, 2860, 2710, 1730, 1670, 1440, 1390 and 1250; δH (500
MHz; CDCl3) 9.74 (t, J 2.0, 1 H, CHO), 5.21 (t, J 7.3, 1 H,
5-H), 5.18–5.04 (m, 4 H, 9-H, 12-H, 16-H, 20-H), 4.17 (s, 2 H,
CH2OSi), 2.55 (td, J 7.3, 2.0, 2 H, 2-H), 2.43 (t, J 7.3, 2 H, 3-H),
2.17–1.88 (m, 16 H, 6-H, 7-H, 10-H, 11-H, 14-H, 15-H, 18-H,
19-H), 1.68 (s, 3 H, vinyl-CH3), 1.60 (s, 12 H, vinyl-CH3), 0.90
(s, 9 H, SiC(CH3)3) and 0.07 (s, 6 H, SiCH3); δC (125 MHz;
CDCl3) 202.8, 136.7, 135.2, 134.9, 134.4, 131.2, 127.1, 124.9,
124.4, 124.2(×2), 60.5, 42.6, 39.7(×3), 28.3, 28.2, 27.3, 26.8,
26.7, 26.1, 25.9(×3), 25.7, 18.3, 17.6, 16.0(×2), 15.9 and
Ϫ5.4(×2) [Found (HRMS): Mϩ, 514.4210. C33H58O2Si requires
M, 516.4206].
(4Z,8E,12E,16E)-4-tert-Butyldimethylsilyloxymethyl-
8,13,17,21-tetramethyldocosa-1,4,8,12,16,20-hexaene 18
To a mixture of 17 (1.3 g, 3.4 mmol) and imidazole (0.47 g, 6.9
mmol) in DMF (4 ml) was added tert-butyldimethylsilyl
chloride (0.68 g, 4.5 mmol). The reaction mixture was stirred
for 4 h at 25 ЊC and quenched with sat. NH4Cl. The
aqueous layer was extracted with Et2O and the combined
organic extracts were washed with water and aqueous NaCl,
dried with MgSO4, and concentrated. The crude product was
purified by column chromatography (silica gel, EtOAc–hexane,
2:98) to give 18 as a colourless oil (1.5 g, 85%); Rf (EtOAc–
hexane, 1:9) 0.9; νmax(neat)/cmϪ1 2980, 2930, 2860, 1640, 1470,
1450, 1380 and 1250; δH (500 MHz; CDCl3) 5.81 (ddt, J 17.4,
10.1, 3.0, 1 H, 2-H), 5.23 (t, J 7.3, 1 H, 5-H), 5.17–5.07 (m, 4 H,
9-H, 12-H, 16-H, 20-H), 5.03 (dtd, J 17.4, 3.4, 1.5, 1 H, 1-H),
5.00 (dtd, J 10.1, 2.1, 1.5, 1 H, 1-H), 4.14 (s, 2 H, CH2OSi), 2.83
(m, 2 H, 3-H), 2.18–1.93 (m, 16 H, 6-H, 7-H, 10-H, 11-H, 14-H,
15-H, 18-H, 19-H), 1.68 (s, 3 H, vinyl-CH3), 1.60 (s, 6 H, vinyl-
CH3), 1.59 (s, 6 H, vinyl-CH3), 0.92 (s, 9 H, SiC(CH3)3) and 0.07
(s, 6 H, SiCH3); δC (125 MHz; CDCl3) 137.1(×2), 135.1, 134.9,
134.6, 131.2, 127.2, 124.7, 124.4, 124.3(×2), 115.5, 60.3, 39.9,
39.8, 39.7, 38.7, 28.3, 28.2, 26.8, 26.7, 26.3, 26.0(×3), 25.7, 18.4,
17.7, 16.0(×3) and Ϫ5.3(×2) [Found (HRMS): Mϩ, 498.4245.
C33H58OSi requires M, 498.4257].
Methyl (2Z,6Z,10E,14E,18E)- and (2E,6Z,10E,14E,18E)-
6-(tert-butyldimethylsilyloxymethyl)-2-isopropylthiomethyl-
10,15,19,23-tetramethyltetracosa-2,6,10,14,18,22-hexanoate
(2Z)- and (2E)-24
To a suspension of NaH (60% in mineral oil, 25 mg, 0.62 mmol,
washed with hexane) in THF (1 ml) was added propane-2-thiol
(0.056 ml, 0.62 mmol) and (EtO) P(O)C(᎐CH )CO Me (0.14 g,
᎐
2
2
2
0.62 mmol) in THF (1 ml) at 0 ЊC. After the mixture had been
stirred for 15 min at 0 ЊC, 23 (0.21 g, 0.42 mmol) in THF (1 ml)
was added to it and stirring was continued for 3 h at 25 ЊC. The
reaction mixture was then poured into aqueous NH4Cl and
extracted with Et2O. The combined extracts were washed
with brine, dried with anhydrous MgSO4, and concentrated.
Preparative TLC (silica gel, hexane–EtOAc, 98:2) of the crude
product gave (2Z)-24 (0.19 g, 70%) and (2E)-24 (0.070 g, 24%)
as colourless oils. For (2Z)-24, Rf (EtOAc–hexane, 1:9) 0.68;
νmax(neat)/cmϪ1 2960, 2860, 1720, 1670, 1640, 1440 and 1250;
δH (500 MHz; CDCl3) 6.82 (t, J 7.3, 1 H, 3-H), 5.24 (t, J 7.3, 1
H, 7-H), 5.18–5.01 (m, 4 H, 11-H, 14-H, 18-H, 22-H), 4.17 (s, 2
H, CH2OSi), 3.75 (s, 3 H, CO2CH3), 3.46 (s, 2 H, CH2S), 2.91
(septet, J 6.7, 1 H, SCH(CH3)2), 2.38 (dt, J 7.6, 7.3, 2 H, 4-H),
2.23 (t, J 7.3, 2 H, 5-H), 2.15–1.83 (m, 16 H, 8-H, 9-H, 12-H,
13-H, 16-H, 17-H, 20-H, 21-H), 1.68 (s, 3 H, vinyl-CH3), 1.60 (s,
12 H, vinyl-CH3), 1.28 (d, J 6.7, 6 H, SCH(CH3)2), 0.90 (s, 9 H,
SiC(CH3)3) and 0.07 (s, 6 H, SiCH3); δC (125 MHz; CDCl3)
167.5, 144.7, 137.3, 135.2, 134.9, 134.6, 131.2, 129.4, 127.1,
124.7, 124.4, 124.2(×2), 60.4, 51.8, 39.8, 39.7(×2), 35.5, 33.5,
28.3, 28.2, 27.8, 26.8, 26.7, 26.3, 26.2, 25.9(×3), 25.7, 23.4(×2),
18.3, 17.7, 16.0(×3) and Ϫ5.3(×2) (Found: C, 72.71; H, 10.75.
C40H70O3SiS requires C, 72.89; H, 10.70%). For (2E)-24, Rf
(EtOAc–hexane, 1:9) 0.78; νmax(neat)/cmϪ1 2960, 2930, 2860,
1730, 1670, 1640, 1440, 1380 and 1250; δH (500 MHz; CDCl3)
5.99 (t, J 7.3, 1 H, 3-H), 5.21 (t, J 7.3, 1 H, 7-H, ), 5.17–5.06 (m,
4 H, 11-H, 14-H, 18-H, 22-H), 4.15 (s, 2 H, CH2OSi), 3.76 (s, 3
H, CO2CH3), 3.37 (s, 2 H, CH2S), 2.82 (septet, J 6.7, 1 H,
SCH(CH3)2), 2.59 (q, J 7.3, 2 H, 4-H), 2.20 (t, J 7.3, 2 H, 5-H),
2.15–1.89 (m, 16 H, 8-H, 9-H, 12-H, 13-H, 16-H, 17-H, 20-H,
(4Z,8E,12E,16E)-4-tert-Butyldimethylsilyloxymethyl-
8,13,17,21-tetramethyldocosa-4,8,12,16,20-pentaen-1-ol 22
To a solution of 18 (0.46 g, 0.93 mmol) in THF (5 ml) was
added 9-BBN (0.5 M in THF) (3.7 ml, 1.8 mmol) at 0 ЊC and
the mixture was stirred for 12 h at 0–25 ЊC. The solution was
cooled to 0 ЊC and water was added. A solution of NaOH (0.17
g, 4.3 mmol) in water (0.43 ml) and 30% aqueous H2O2 (0.43 g,
3.7 mmol) were added to the reaction mixture at 0 ЊC and the
resulting mixture was stirred at 0–25 ЊC. After stirring for 12 h,
water was added and the aqueous layer was extracted with
Et2O. The combined organic extracts were washed with water
and brine, dried with anhydrous Na2SO4, and concentrated. The
crude product was purified by column chromatography (silica
gel, EtOAc–hexane, 5:95) to give 22 as a colourless oil (0.40 g,
83%); Rf (EtOAc–hexane, 1:9) 0.3; νmax(neat)/cmϪ1 3340, 2930,
2860, 1700, 1670, 1450, 1380 and 1250; δH (500 MHz; CDCl3)
5.25 (t, J 7.0, 1 H, 5-H), 5.17–5.06 (m, 4 H, 9-H, 12-H, 16-H,
20-H), 4.17 (s, 2 H, CH2OSi), 3.62 (t, J 6.1, 2 H, CH2OH), 2.21–
1.92 (m, 18 H, 3-H, 6-H, 7-H, 10-H, 11-H, 14-H, 15-H, 18-H,
J. Chem. Soc., Perkin Trans. 1, 1999, 489–496
495