1842 J . Org. Chem., Vol. 63, No. 6, 1998
Paquette et al.
2 H), 3.79 (s, 3 H), 2.50-2.40 (m, 1 H), 1.88-1.68 (m, 5 H),
1.42-1.13 (m, 5 H); 13C NMR (75 MHz, CDCl3) ppm 166.4,
152.9, 127.3, 52.1, 38.2, 31.5 (2 C), 25.7, 25.2 (2 C), 24.4; MS
m/z (M+ - Br) calcd 181.1228, obsd 181.1230.
3.77-3.68 (m, 2 H), 2.62-2.52 (m, 1 H), 1.90-1.57 (m, 7 H),
1.32-1.05 (m, 2 H), 1.03-0.80 (m, 2 H), 0.86 (s, 9 H), 0.00 (s,
6 H); 13C NMR (75 MHz, CDCl3) ppm 168.2, 141.2, 125.8, 63.2,
51.7, 48.7, 38.1, 31.0 (2 C), 26.5, 26.4 (2 C), 25.8 (3 C), 18.4,
-5.5, -5.6; MS m/z (M+) calcd 326.2277, obsd 326.2249.
Gen er a l P r oced u r e for DIBAL-H Red u ction a n d Br o-
m in a tion of 7. A cold (-78 °C), magnetically stirred solution
of 7a (18.2 g, 75 mmol) in dry THF (32 mL) was treated
dropwise with DIBAL-H (153 mL of 1 M in hexanes, 153
mmol). After 3 h at this temperature and 1 h at 0 °C,
saturated Rochelle salt solution (200 mL) was introduced and
the heterogeneous reaction mixture was allowed to warm to
room temperature overnight. The separated aqueous phase
was extracted with ethyl acetate, and the combined organic
solutions were washed with brine, dried, and concentrated.
Purification of the residue by chromatography on silica gel
(elution with 1:1 hexanes/ethyl acetate) gave the alcohol as a
colorless oil (3.3 g, 73%); IR (CH2Cl2, cm-1) 3450, 1635; 1H
NMR (300 MHz, CDCl3) δ 5.07 (s, 1 H), 4.92 (s, 1 H), 4.07 (dd,
J ) 23.7, 12.7 Hz, 2 H), 3.60 (dd, J ) 9.6, 5.4 Hz, 1 H), 3.53
(dd, J ) 9.6, 7.0 Hz, 1 H), 2.87 (br s, 1 H), 2.44 (dd, J ) 12.8,
6.7 Hz, 1 H), 1.06 (d, J ) 7.0 Hz, 3 H), 0.89 (s, 9 H), 0.06 (s, 6
H); 13C NMR (75 MHz, CDCl3) ppm 151.9, 111.2, 68.7, 65.6,
39.8, 25.8 (3 C), 18.3, 16.3, -5.5; MS m/z (M+) calcd 230.1702,
obsd 230.1691.
Gen er a l Hyd r oxym eth yla tion P r oced u r e. A mixture of
5a (0.93 g, 4.8 mmol), indium powder (0.65 g, 5.4 mmol), THF
(20 mL), and aqueous formaldehyde (20 mL of 37%, excess)
was stirred vigorously for 20 h. The milky-white mixture was
diluted with ethyl acetate, and the separated aqueous phase
was extracted with this solvent (3 × 10 mL). The combined
organic layers were washed with brine, dried, and concen-
trated. Chromatography of the residue on silica gel (elution
with 10% hexanes/ethyl acetate) gave 6a as a colorless oil (0.43
g, 62%); IR (CH2Cl2, cm-1) 3340, 1700, 1627; 1H NMR (300
MHz, CDCl3) δ 6.23 (s, 1 H), 5.60 (s, 1 H), 3.75 (s, 3 H), 3.74-
3.58 (m, 3 H), 3.12-2.87 (m 1 H), 1.12 (d, J ) 7.0 Hz, 3 H);
13C NMR (75 MHz, CDCl3) ppm 167.8, 142.8, 124.6, 63.3, 51.9,
35.2, 15.2; MS m/z (M+) calcd 144.0786, obsd 144.0791. Anal.
Calcd for C7H12O3: C, 58.30; H, 8.39. Found: C, 58.07; H, 8.34.
6b: colorless oil (75%); IR (CH2Cl2, cm-1) 3620, 1720; 1H
NMR (300 MHz, CDCl3) δ 6.29 (d, J ) 1.2 Hz, 1 H), 5.60 (dd,
J ) 0.75, 1.1 Hz, 1 H), 3.77 (dd, J ) 7, 3 Hz, 1 H), 3.75 (s, 3
H), 3.74 (dd, J ) 7, 3 Hz, 1 H), 2.45 (m, 1 H), 1.90 (m, 1 H),
0.96 (d, J ) 6.9 Hz, 3 H), 0.84 (d, J ) 6.9 Hz, 3 H); 13C NMR
(75 MHz, CDCl3) ppm 168.3, 140.8, 126.2, 62.7, 51.6, 50.5, 27.6,
20.5, 20.1; MS m/z (M+) calcd 172.1099, obsd 172.1093. Anal.
Calcd for C9H16O3: C, 62.75; H, 9.37. Found: C, 62.47; H, 9.31.
6c: colorless oil (70%); IR (CHCl3, cm-1) 3435, 1717, 1628;
1H NMR (300 MHz, CDCl3) δ 7.35-7.15 (m, 5 H), 6.39 (s, 1
H), 5.70 (s, 1 H), 4.10 (t, J ) 6.9 Hz, 1 H), 3.93 (m, 2 H), 3.66
(s, 3 H), 2.24 (br, 1 H); 13C NMR (75 MHz, CDCl3) ppm 167.2,
140.4, 139.5, 128.4 (2 C), 128.1 (2 C), 126.9, 125.6, 64.8, 51.8,
48.7; MS m/z (M+) calcd 206.0943, obsd 206.0954.
Alcoh ol fr om 7b: colorless oil (84%); IR (CH2Cl2, cm-1
)
1
3455, 1648; H NMR (300 MHz, CDCl3) δ 5.13 (s, 1 H), 4.90
(s, 1 H), 4.09 (dd, J ) 12.5, 2.6 Hz, 1 H), 3.96 (dd, J ) 12.4,
5.8 Hz, 1 H), 3.77 (dd, J ) 9.7, 4.0 Hz, 1 H), 3.66 (dd, J ) 9.7,
7.5 Hz, 1 H), 3.00 (s, 1 H), 2.00-1.93 (m, 1 H), 1.84-1.77 (m,
1 H), 0.95 (d, J ) 6.5 Hz, 3 H), 0.89 (s, 9 H), 0.85 (d, J ) 6.6
Hz, 3 H), 0.06 (s, 6 H); 13C NMR (75 MHz, CDCl3) ppm 150.4,
113.0, 66.3, 65.8, 53.1, 28.0, 25.8 (3 C), 21.3, 20.8, 18.2, -5.5
(2 C), -5.6; MS m/z (M+) calcd 258.2015, obsd 258.1981. Anal.
Calcd for C14H30O2Si: C, 65.07; H, 11.71. Found: C, 64.98;
H, 11.72.
6d : colorless oil (90%); IR (CH2Cl2, cm-1) 3478, 1708, 1624;
1H NMR (300 MHz, CDCl3) δ 6.27 (s, 1 H), 5.59 (s, 1 H), 3.76
(s, 3 H), 3.84-3.68 (m, 2 H), 2.51 (td, J ) 8.1, 4.2 Hz, 1 H),
1.92-1.82 (m, 1 H), 1.81-1.50 (m, 6 H), 1.37-1.06 (m, 3 H),
0.99-0.84 (m, 2 H); 13C NMR (75 MHz, CDCl3) ppm 168.4,
141.1, 126.5, 101.6, 63.1, 52.0, 50.5, 37.3, 31.3, 30.8, 26.2 (2
C); MS m/z (M+) calcd 212.1412, obsd 212.1446. Anal. Calcd
for C12H20O3: C, 67.88; H, 9.50. Found: C, 67.83; H, 9.48.
Gen er a l P r oced u r e for th e Silyla tion of 6. A mixture
of 6a (5.7 g, 43.8 mmol), tert-butyldimethylchlorosilane (8.0
g, 52.9 mmol), imidazole (9.53 g, 131 mmol), and CH2Cl2 (170
mL) was stirred magnetically for 17 h and diluted with water.
The separated aqueous phase was extracted with CH2Cl2, and
the combined organic solutions were washed with brine, dried,
and concentrated. Chromatography of the residue on silica
gel (elution with 20:1 hexanes/ethyl acetate) furnished 7a as
Alcoh ol fr om 7c: colorless oil (90%); IR (CHCl3, cm-1
)
1
3406; H NMR (300 MHz, CDCl3) δ 7.35-7.18 (m, 5 H), 5.25
(d, J ) 1.2 Hz, 1 H), 5.04 (s, 1 H), 4.04 (dd, J ) 9.9, 7.2 Hz, 1
H), 4.01 (s, 2 H), 3.91 (dd, J ) 9.9, 6.3 Hz, 1 H), 3.56 (t, J )
7.0 Hz, 1 H), 2.30 (br, 1 H), 0.86 (s, 9 H), -0.02 (s, 3 H), -0.03
(s, 3 H); 13C NMR (75 MHz, CDCl3) ppm 149.1, 140.9, 128.3 (2
C), 128.2 (2 C), 126.6, 111.5, 66.2, 65.8, 50.7, 25.8 (3 C), 18.2,
-5.6, -5.7; MS m/z (M+ + H) calcd 293.1867, obsd 293.1974.
Anal. Calcd for C17H28O2Si: C, 69.81; H, 9.65. Found: C,
69.67; H, 9.60.
Alcoh ol fr om 7d : colorless oil (65%); IR (CH2Cl2, cm-1
)
1
3428, 1641; H NMR (300 MHz, CDCl3) δ 5.12 (s, 1 H), 4.89
(s, 1 H), 4.07 (d, J ) 12.4 Hz, 1 H), 3.94 (d, J ) 12.5 Hz, 1 H),
3.76 (dd, J ) 9.7, 4.0 Hz, 1 H), 3.67 (dd, J ) 9.6, 7.6 Hz, 1 H),
3.04 (br s, 1 H), 2.08-2.01 (m, 1 H), 1.82-1.57 (m, 5 H), 1.57-
1.43 (m, 1 H), 1.26-1.10 (m, 2 H), 1.02-0.78 (m, 3 H), 0.89 (s,
9 H), 0.06 (s, 6 H); 13C NMR (75 MHz, CDCl3) ppm 150.3, 113.1,
66.2, 65.2, 51.8, 37.5, 31.4, 31.1, 26.5, 26.34, 26.27, 25.8 (3 C),
18.4, -5.5 (2 C); MS m/z (M+ - OH) calcd 281.2301, obsd
281.2322. Anal. Calcd for C17H34O2Si: C, 68.40; H, 11.49.
Found: C, 68.18; H, 11.38.
1
a colorless oil (5.4 g, 64%); IR (CHCl3, cm-1) 1704; H NMR
(300 MHz, CDCl3) δ 6.21 (s, 1 H), 5.57 (s, 1 H), 3.74 (s, 3 H),
3.65 (dd, J ) 9.7, 5.5 Hz, 1 H), 3.45 (dd, J ) 9.7, 6.6 Hz, 1 H),
2.87 (q, J ) 6.7 Hz, 1 H), 1.10 (d, J ) 7.0 Hz, 3 H), 0.87 (s, 9
H), 0.01 (s, 6 H); 13C NMR (75 MHz, CDCl3) ppm 167.7, 142.8,
124.5, 66.9, 51.7, 37.4, 25.8 (3 C), 18.2, 16.1, -5.5 (2 C); MS
m/z (M+) calcd 258.1651, obsd 258.1676.
7b: colorless oil (75%); IR (CH2Cl2, cm-1) 1710; 1H NMR
(300 MHz, CDCl3) δ 6.27 (s, 1 H), 5.58 (s, 1 H), 3.75-3.64 (m,
2 H), 3.74 (s, 3 H), 2.53-2.46 (m, 1 H), 1.95-1.88 (m, 1 H),
0.94 (d, J ) 6.7 Hz, 3 H), 0.85 (s, 9 H), 0.83 (d, J ) 6.8 Hz, 3
H), 0.00 (s, 3 H), -0.02 (s, 3 H); 13C NMR (75 MHz, CDCl3)
ppm 168.1, 141.2, 125.8, 63.5, 51.7, 49.6, 28.3, 25.8 (3 C), 20.8,
20.6, 18.2, -5.5, -5.6; MS m/z (M+) calcd 286.1964, obsd
286.1929.
A solution of the alcohol derived from 7a (19.14 g, 88.6
mmol) in dry CH2Cl2 (175 mL) was cooled to -40 °C and
treated under N2 with triphenylphosphine (27.9 g, 106 mmol)
and N-bromosuccinimide (17.35 g, 97.5 mmol). The mixture
was stirred for 1 h, diluted with ether (200 mL), washed with
saturated NaHCO3 solution and brine, dried, and concentrated.
The residue was triturated with pentane (250 mL), and the
solids were removed by filtration. Chromatography of the
evaporated filtrate on silica gel (elution with 20:1 hexanes/
ethyl acetate) gave 8a as a colorless oil (3.4 g, 82%); 1H NMR
(300 MHz, CDCl3) δ 5.24 (s, 1 H), 5.01 (s, 1 H), 4.04 (dd, J )
17.1, 10.0 Hz, 2 H), 3.60 (dd, J ) 9.7, 6.1 Hz, 1 H), 3.53 (dd, J
) 9.7, 6.5 Hz, 1 H), 2.55 (q, J ) 6.7 Hz, 1 H), 1.11 (d, J ) 7.0
Hz, 3 H), 0.89 (s, 9 H), 0.04 (s, 6 H); 13C NMR (75 MHz, CDCl3)
ppm 148.5, 114.8, 67.9, 39.2, 37.3, 25.9 (3 C), 18.3, 16.7, -5.4
(2 C); MS m/z (M+) calcd 292.0858, obsd 292.0897.
7c: colorless oil (85%); IR (CHCl3, cm-1) 1716; 1H NMR (300
MHz, CDCl3) δ 7.35-7.18 (m, 5 H), 6.39 (s, 1 H), 5.72 (s, 1 H),
4.07 (t, J ) 6.5 Hz, 1 H), 3.92 (m, 2 H), 3.68 (s, 3 H), 0.84 (s,
9 H), -0.04 (s, 3 H), -0.05 (s, 3 H); 13C NMR (75 MHz, CDCl3)
ppm 167.4, 140.7, 140.5, 128.4 (2 C), 128.2 (2 C), 126.6, 125.6,
65.4, 51.8, 48.9, 25.8 (3 C), 18.2, -5.5, -5.6; MS m/z (M+
-
OCH3) calcd 320.1808, obsd 320.1777. Anal. Calcd for C18H28
-
O3Si: C, 67.46; H, 8.81. Found: C, 67.54; H, 8.82.
1
1
7d : colorless oil (100%); IR (CH2Cl2, cm-1) 1715; H NMR
8b: colorless oil (77%); H NMR (300 MHz, CDCl3) δ 5.31
(300 MHz, CDCl3) δ 6.27 (s, 1 H), 5.58 (s, 1 H), 3.74 (s, 3 H),
(s, 1 H), 5.02 (s, 1 H), 4.00 (dd, J ) 3.3, 0.8 Hz, 2 H), 3.68 (dd,