Vestergaard et al.
Compound 4. Method 1: To a solution of compound 3
(0.113 g, 0.138 mmol) in THF (4 mL) and MeOH (15 mL)
was added K2CO3 (0.027 g, 0.20 mmol). After stirring for 30
min, the mixture was diluted with Et2O (100 mL), washed with
H2O (50 mL) and brine (50 mL), dried (MgSO4), and concen-
trated in vacuo. The residue was redissolved in CH2Cl2 (15 mL),
and then Hay catalyst (10.0 mL) was added [Hay catalyst: CuCl
(0.26 g) and TMEDA (0.32 g) in CH2Cl2 (10 mL)]. After stirring
for 2 h under air, more CH2Cl2 (20 mL) was added, and
the mixture was stirred under air overnight. Then CH2Cl2
(100 mL) was added, and the mixture was washed with H2O
(50 mL) and brine (50 mL). The organic phase was dried
(MgSO4) and concentrated in vacuo. Column chromatography
(SiO2, CH2Cl2) gave the product 4 (0.021 g, 19%) as a red
solid.
Compound 15. The tetraester 14 (0.100 g, 0.126 mmol) was
dissolved in dry THF (7 mL) and cooled to 0 °C. DIBAL-H
(1.40 mL, 1.40 mmol, 1 M in hexane) was added over a period
of 5 min. After stirring for 3 h at 0 °C, the reaction mixture
was allowed to warm to rt. After stirring for another 24 h, H2O
(2 mL) was added, and the mixture was poured into CH2Cl2
(100 mL). The organic phase was washed with 0.08 M HCl (2
× 50 mL), brine (50 mL), dried (MgSO4), filtered, and
evaporated to dryness under reduced pressure to give the product
1
15 (0.073 g, 85%) as slightly yellow crystals. H NMR (300
MHz, CDCl3): δ ) 1.13 (m, 42H), 1.94 (t, J ) 6.5 Hz, 2H),
2.14 (t, J ) 6.5 Hz, 2H), 4.83 (d, J ) 6.5 Hz, 4H), 4.86 (d, J
) 6.5 Hz, 4H), 7.62 (s, 2H), 7.64 (s, 2H). 13C NMR (75 MHz,
CDCl3): δ ) 11.5, 18.9, 63.2, 63.5, 79.7, 81.0, 99.6, 103.9,
119.9, 122.8, 131.5, 131.7, 142.5, 143.2. HR-MS (FAB): m/z
) 682.3891 [M+] calcd for C42H58O4Si2, 682.3874.
Method 2: The tetraaldehyde 5 (0.050 g, 0.075 mmol) and
phosphonium salt 12 (0.188 g, 0.370 mmol) were dissolved in
a mixture of dry THF (10 mL) and dry MeCN (3 mL),
whereupon NEt3 (0.072 mL, 0.520 mmol) was added. After
stirring for 3 h at rt, the reaction mixture was poured into CH2-
Cl2 (150 mL). The mixture was washed with water (2 × 50
mL) and brine (50 mL), dried (MgSO4), filtered, and evaporated
to dryness under reduced pressure. Column chromatography
(SiO2, CH2Cl2) gave the product 4 as a red solid (0.102 g, 92%).
Mp 207-210 °C dec. 1H NMR (300 MHz, CDCl3): δ ) 1.16
(m, 42H), 3.86-3.88 (3× s, 24H), 6.87 (s, 2H), 6.96 (s, 2H),
7.48 (s, 2H), 7.50 (s, 2H). 13C NMR (75 MHz, CDCl3): δ )
11.5, 18.9, 53.5 (×2; i.e., two signals), 53.6 (two overlapping;
i.e., one signal), 80.5, 82.0, 100.3, 104.6, 112.0, 112.3, 119.8,
123.0, 129.4, 129.5, 129.6, 132.0, 134.1, 134.9, 135.1, 136.1,
159.7 (two overlapping), 160.1, 160.2; two signals overlapping.
MS (FAB): m/z ) 1481.5 [M+]. Anal. Calcd. for C70H74O16S8-
Si2: C, 56.65; H, 5.03. Found: C, 56.56; H, 4.94.
Compound 5. The tetraol 15 (0.071 g, 0.104 mmol) was
dissolved in dry CH2Cl2 (15 mL), whereupon molecular sieves
(4 Å), Celite (1 g), and PCC (0.157 g, 0.728 mmol) were
added. After stirring for 3 h at rt, the mixture was filtered
through a dry column (SiO2), and the column was washed
with additional CH2Cl2 (100 mL). The combined organic
fractions were evaporated to dryness under reduced pressure to
1
give the product 5 (0.060 g, 86%) as a white solid. H NMR
(300 HMz, CDCl3): δ ) 1.14-1.16 (m, 42H), 8.12 (s, 2H),
8.20 (s, 2H), 10.51 (s, 2H), 10.60 (s, 2H). 13C NMR (75,
CDCl3): δ ) 11.4, 18.8, 79.4, 81.7, 100.5, 104.7, 123.5, 127.8,
133.6, 133.8, 138.9, 139.9, 189.4, 190.0. MS (FAB): m/z )
675.3 [M+]. Anal. Calcd for C42H50O4Si2: C, 74.73; H, 7.47.
Found: C, 74.59; 7.73.
Compound 16. The triflate 8 (1.00 g, 2.14 mmol) was
dissolved in dry CH2Cl2 (6 mL) and cooled to -78 °C.
DIBAL-H (1 M in hexane, 9.65 mL, 9.65 mmol) was added
over a period of 5 min. After stirring for 45 min at -78 °C, the
solution was allowed to warm to rt, and after another 2 h it was
poured into CH2Cl2 (450 mL). The combined organic phase was
washed with 0.08 M HCl (100 mL) and saturated aqueous NH4-
Cl (100 mL). The organic phase was dried (MgSO4), filtered,
and evaporated to dryness under reduced pressure to give the
product 16 as a white solid (0.619 g, 75%). Mp 89-92 °C. 1H
NMR (300 MHz, CDCl3): δ ) 0.26 (s, 9H), 1.89 (t, J ) 6.2
Hz, 1H), 2.10 (t, J ) 6.2 Hz, 1H), 4.77 (d, J ) 6.2 Hz, 2H),
4.84 (d, J ) 6.2 Hz, 2H), 7.42 (s, 1H), 7.70 (s, 1H). 13C NMR
(75 MHz, CDCl3): δ ) 0.0, 59.3, 62.9, 100.4, 102.2, 119.7,
120.8, 121.5, 132.6, 133.8, 145.4, 146.7. MS (FAB): m/z )
383.2 [M+]. Anal. Calcd for C14H17F3O5SSi: C, 43.97; H, 4.48.
Found: C, 44.22; H, 4.51.
Compound 13. Compound 9 (0.563 g, 1.13 mmol) and K2-
CO3 (0.138 g, 1.00 mmol) were dissolved in THF (20 mL),
whereupon MeOH (10 mL) was added. After stirring for 8 h at
rt under an argon atmosphere, the mixture was poured into CH2-
Cl2 (150 mL). The organic phase was washed with water (3 ×
100 mL), brine (75 mL), dried (MgSO4), filtered, and evaporated
to dryness under reduced pressure to give the product (0.360 g,
1
80%) as a yellow solid. Mp 78-79 °C. H NMR (300 MHz,
CDCl3): δ ) 1.15 (m, 21H), 3.50 (s, 1H), 3.92 (s, 3H), 3.96
(s, 3H), 8.08 (s, 1H), 8.10 (s, 1H). 13C NMR (75 MHz,
CDCl3): δ ) 11.4, 18.8, 52.8, 81.0, 84.7, 100.3, 103.6, 122.0,
123.5, 134.8, 135.3, 136.6, 136.7, 165.4, 165.7. MS (FAB): m/z
) 399.1 [M + H+]. Anal. Calcd for C23H30O4Si: C, 69.31; H,
7.59. Found: C, 69.34; H, 7.66.
Compound 17. A mixture of the diol 16 (0.550 g, 1.44
mmol), PCC (1.085 g, 5.03 mmol), Celite (2.0 g), and molecular
sieves (4 Å) in dry CH2Cl2 (40 mL) was stirred for 3 h at rt.
Then the reaction mixture was filtered through a short, dry silica
gel column, and the column was washed with additional
CH2Cl2 (150 mL). Concentration in vacuo gave the product 17
as an oil, which slowly solidified upon standing (0.506 g,
93%). Mp 49-52 °C. 1H NMR (300 MHz, CDCl3): δ ) 0.30
(s, 9H), 7.88 (s, 1H), 8.17 (s, 1H), 10.28 (s, 1H), 10.53 (s, 1H).
13C NMR (75 MHz, CDCl3): δ ) -0.3, 97.2, 107.1, 120.9,
121.2, 127.2, 131.6, 136.3, 140.7, 148.9, 185.3, 189.2. MS
(FAB): m/z ) 379.0266 [M + H+] calcd for C14H14F3O5SSi2,
379.0283.
Compound 14. Compound 13 (0.635 g, 1.49 mmol) was
dissolved in CH2Cl2 (50 mL). Then Hay catalyst (1.5 mL) was
added, and the mixture was vigorously stirred under air for 14
h. The mixture was diluted with CH2Cl2 (100 mL), and the
organic phase was washed with water (2 × 100 mL), brine (100
mL), dried (MgSO4), filtered, and evaporated to dryness under
reduced pressure to a red foam. Column chromatography (SiO2,
EtOAc/heptane 1:9) gave the product 14 (0.430 g, 68%) as
1
slightly yellow crystals. Mp 153-55 °C. H NMR (300 MHz,
CDCl3): δ ) 1.15 (m, 42H), 3.93 (s, 6H), 3.99 (s, 6H), 8.13
(s, 2H), 8.15 (s, 2H). 13C NMR (75 MHz, CDCl3): δ ) 11.4,
18.8, 52.8, 53.0, 80.9, 81.7, 101.2, 103.7, 121.6, 123.9, 134.9,
135.4, 137.0 (×2; i.e., two signals), 165.0, 165.5. MS (FAB):
m/z ) 795.6 [M + H+]. Anal. Calcd for C46H58O8Si2: C, 69.49;
H, 7.35. Found: C, 69.78; H, 7.57.
Compound 18. The dialdehyde 17 (0.449 g, 1.19 mmol) and
phosphonium salt 12 (1.507 g, 2.97 mmol) were dissolved in a
3182 J. Org. Chem., Vol. 73, No. 8, 2008