8310
E. Tayama et al. / Tetrahedron 58 (2002) 8307–8312
1.3. Preparation of optically pure bis(binaphthol)
(S,S)-2b (R05H)
The resulting pale-brown suspension was cooled to 2788C
and a solution of iodine (323 mg, 2.1 mmol) in THF (2 mL)
was added dropwise slowly. The mixture was warmed to
room temperature and stirring was continued for 3 h. The
excess iodine was reduced by addition of saturated Na2SO3
and the mixture was extracted with Et2O. The combined
extracts were washed with brine, dried over Na2SO4 and
concentrated. The crude product was dissolved into
1,4-dioxane (4.6 mL) and conc. HCl (2.3 mL) was added.
After stirring at 508C for 15 h, the resulting mixture was
diluted with H2O and extracted with Et2O. The combined
extracts were washed with brine and dried over Na2SO4.
Evaporation of solvents and purification of the residue by
column chromatography on silica gel (hexane/CH2Cl2¼2:1
as eluent) gave (S)-8 (692 mg, 1.06 mmol, 77% yield) as
1.3.1. (S)-2-tert-Butyldiphenylsilyloxy-20-hydroxy-1,10-
binaphthyl [(S)-5].7 To a solution of (S)-binaphthol
(4.29 g, 15.0 mmol) and imidazole (2.04 g, 30 mmol) in
DMF (30 mL) was added tert-butyldiphenylsilyl chloride
(4.1 mL, 16 mmol) and the mixture was stirred at 508C for
4 h under argon. After the resulting mixture was cooled
to room temperature, saturated NH4Cl was added and
extractive workup was performed with Et2O. The combined
extracts were washed with brine and dried over Na2SO4.
Evaporation of solvents and purification of the residue by
column chromatography on silica gel (hexane/CH2Cl2¼2:1
as eluent) gave (S)-5 (7.27 g, 13.9 mmol, 92% yield) as
1
1
colorless crystal. [a]2D0¼þ36.48 (c 1.0, CHCl3); H NMR
colorless crystal. [a]2D5¼þ31.48 (c 1.0, CHCl3); H NMR
(400 MHz, CDCl3) d 7.93 (1H, d, J¼9.2 Hz, Ar–H), 7.88
(1H, dd, J¼8.4, 1.6 Hz, Ar–H), 7.77 (1H, dt, J¼7.6, 1.6 Hz,
Ar–H), 7.64–7.60 (3H, m, Ar–H), 7.54–7.51 (2H, m,
Ar–H), 7.44–7.26 (12H, m, Ar–H), 7.20 (1H, m, Ar–H),
6.89 (1H, d, J¼8.8 Hz, Ar–H), 5.02 (1H, s, OH), 0.49 (9H,
s, t-Bu); IR (KBr) 3531, 3055, 2957, 2930, 2891, 2856,
1620, 1591, 1504, 1472, 1460, 1429, 1362, 1339, 1277,
(400 MHz, CDCl3) d 8.48 (1H, s, Ar–H), 7.77 (2H, d, J¼
7.2 Hz, Ar–H), 7.64–7.60 (3H, m, Ar–H), 7.50 (2H, dd,
J¼7.2, 1.6 Hz, Ar–H), 7.43 (1H, tt, J¼7.2, 1.6 Hz, Ar–H),
7.38–7.25 (10H, m, Ar–H), 7.14 (1H, dd, J¼8.4, 0.8 Hz,
Ar–H), 6.88 (1H, d, J¼8.8 Hz, Ar–H), 5.49 (1H, s, OH),
0.52 (9H, s, t-Bu); IR (KBr) 3504, 3051, 2963, 2932, 2856,
1620, 1591, 1502, 1466, 1427, 1356, 1340, 1279, 1261,
1246, 1202, 1146, 1115, 1078, 1034, 1003, 816, 746,
702 cm21. HRMS (FAB) calcd for C36H31IO2Si (Mþ):
650.1138, found: 650.1133.
1263, 1248, 1207, 1148, 1115, 1005, 814, 745, 700 cm21
.
1.3.2. (S)-2-tert-Butyldiphenylsilyloxy-20-methoxy-
methoxy-1,10-binaphthyl [(S)-7]. To a solution of (S)-5
(849 mg, 1.62 mmol) in THF (8 mL) was added NaH
(60 wt% in oil, 84 mg, 2.1 mmol) at 08C and the mixture
was warmed to room temperature and stirred there for 0.5 h.
It was then cooled again to 08C and chloromethyl methyl
ether (0.14 mL, 1.9 mmol) was added. After stirring at room
temperature for 12 h, saturated NH4Cl was added slowly at
08C and then extractive workup was conducted with
Et2O. The combined extracts were washed with brine and
dried over Na2SO4. Evaporation of solvents and purification
of the residue by silica gel column chromatography
(hexane/CH2Cl2¼4:1–1:1 as eluent) gave (S)-7 (833 mg,
1.46 mmol, 90% yield) as colorless crystal. [a]2D3¼255.28
(c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3) d 7.96 (1H, d,
J¼9.2 Hz, Ar–H), 7.89 (1H, d, J¼8.0 Hz, Ar–H), 7.76–
7.73 (1H, m, Ar–H), 7.64–7.61 (3H, m, Ar–H), 7.57–7.53
(3H, m, Ar–H), 7.42–7.20 (12H, m, Ar–H), 6.84 (1H, d,
J¼9.2 Hz, Ar–H), 5.11 (1H, d, J¼6.8 Hz, CH), 5.04 (1H, d,
J¼6.8 Hz, CH), 3.19 (3H, s, Me), 0.45 (9H, s, t-Bu); IR
(KBr) 3053, 2957, 2930, 2893, 2856, 1622, 1591, 1506,
1474, 1460, 1429, 1356, 1339, 1279, 1265, 1250, 1240,
1150, 1115, 1074, 1034, 1005, 812, 746, 702 cm21. HRMS
(FAB) calcd for C38H36O3Si (Mþ): 568.2434, found:
568.2435.
1.3.4. (S)-2-Acetoxy-20-tert-butyldiphenylsilyloxy-3-iodo-
1,10-binaphthyl [(S)-9]. To a solution of (S)-8 (634 mg,
0.974 mmol) in CH2Cl2 (2 mL) was added 4-dimethyl-
aminopyridine (2 mg, 0.002 mmol), pyridine (0.12 mL,
1.5 mmol) and acetic anhydride (0.14 mL, 1.5 mmol)
sequentially, and the solution was stirred for 6 h at room
temperature. The resulting solution was concentrated and
purification of the residue by column chromatography on
silica gel (hexane/CH2Cl2¼3:1–1.5:1 as eluent) afforded
(S)-9 (634 mg, 0.915 mmol, 94% yield) as colorless crystal.
[a]2D5¼þ39.48 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3)
d 8.54 (1H, s, Ar–H), 7.84 (1H, d, J¼8.4 Hz, Ar–H),
7.74–7.69 (3H, m, Ar–H), 7.54–7.24 (15H, m, Ar–H),
6.78 (1H, d, J¼9.2 Hz, Ar–H), 1.85 (3H, s, CH3CO), 0.52
(9H, s, t-Bu); IR (KBr) 3071, 2955, 2930, 2856, 1774, 1624,
1593, 1508, 1470, 1429, 1360, 1354, 1340, 1279, 1261,
1248, 1182, 1115, 1082, 1036, 1009, 824, 748, 702 cm21
.
HRMS (FAB) calcd for C38H33IO3Si (Mþ): 692.1244,
found: 692.1252.
1.3.3. (S)-2-tert-Butyldiphenylsilyloxy-20-hydroxy-30-
iodo-1,10-binaphthyl [(S)-8]. To a solution of (S)-7
(791 mg, 1.39 mmol) in Et2O (4.5 mL) was added a 1.6 M
hexane solution of n-BuLi (1.1 mL, 1.8 mmol) at room
temperature under argon and the mixture was stirred for 3 h.