Suzuki et al.
extracted with Et2O, dried over anhydrous MgSO4, and puri-
fied by silica gel column chromatography with hexane/toluene
Racemic (4-methoxynaphth-1-yl)methylphenylsilylstananne
was prepared in the same way.
) 10:1- 10:2 to give 0.22 g (49%) of a highly viscous oil. [R
D
(S,S)-1,2-Dim et h yl-1,2-d i(4-m et h oxyn a p h t h -1-yl)-1,2-
diph en yldisialn e (S,S)-9. To (R)-8 from (S)-(4-methoxynaphth-
1-yl)methylphenylsilylstananne (1.3 g, 2.95 mmol, 96% ee) was
slowly added (R)-7 (0.87 g, 2.95 mmol, >99% ee) in THF (15
mL) at -78 °C, and the reaction system was stirred for 30
min at the temperature. Decomposition with 1 N HCl, extrac-
tion with Et2O, concentration, and addition of hexane led to
the precipitation of meso-9 as a colorless solid at 0 °C. The
crude product from the solution was purified by column
chromatography (hexane/ethyl acetate ) 40/1, Rf ) 0.22) to
give (S,S)-9 (0.70 g, 43%, (S,S); >99% ee) as a colorless solid.
25
]
) +13.99 (c ) 1.0, cyclohexane). 1H NMR δ 0.51 (s, 3H,
NpOMeSiMe), 0.59 (s, 3H, NpOMeSiMe), 0.74 (s, 3H, NpSiMe),
4.00 (s, 3H, NpOMe), 6.76-6.77 (d, J ) 7.8 Hz, 1H), 6.99-
7.02 (m, 1H), 7.13-7.16 (m, 1H), 7.27-7.45 (m, 8H), 7.56-
7.57 (d, J ) 7.8 Hz, 1H), 7.59-7.61 (m, 2H), 7.80-7.83 (t, J )
7.8 Hz, 3H), and 8.22-8.24 (d, J ) 8.2 Hz, 1H). 13C NMR δ
-2.32, -1.04, -0.96, 55.38, 103.44, 122.22, 124.66, 125.20
(overlapped), 125.32, 125.63, 127.81, 128.42, 128.62 (over-
lapped), 128.70, 129.26, 129.81, 133.35, 133.81, 134.42, 135.08,
135.29, 135.40, 137.19, 137.97, 138.03, 156.68. 29Si NMR δ
-20.85 (overlapped). Anal. Calcd for C30H30OSi2: C, 77.87;
6.53. Found: C, 77.23; H, 6.66.
[R ]27 ) -9.689 (c ) 1.01, cyclohexane). (S, S)-(-)-9 tR ) 100
D
min, (R, R)-(+)-9 tR ) 146 min. 1H NMR δ 0.79 (s, 6H,
(-SiCH3)2), 3.98 (s, 6H, (-NpOCH3)2), 6.67 (d, J ) 7.8 Hz, 2H,
aromatic), 7.02-7.05 (m, 2H, aromatic), 7.17-7.24 (m, 4H,
aromatic), 7.30-7.36 (m, 6H, aromatic), 7.47 (s, 2H, aromatic).
7.66 (d, 2H, J ) 8.7 Hz, aromatic), 7.67 (d, 2H, J ) 7.8 Hz,
aromatic), 8.25 (d, J ) 8.2 Hz, 2H, aromatic). 13C NMR δ
-2.399 (SiCH3, S, S), 55.37, 103.400, 122.28, 124.74, 125.45,
125.84, 125.92, 127.71, 128.61, 128.98, 135.27, 137.15, 137.84,
138.13, 157.04. 29Si NMR δ -20.29. Anal. Calcd for C36H34O2-
Si2: C, 77.93; H, 6.18. Found: C, 77.44; H, 6.20.
(R)-6 fr om MeONp Me2SiLi a n d 2X (X ) Cl, Br , (S)-for m ;
X ) F , (R)-for m ). To (4-methoxynaphth-1-yl)dimethysilyl-
lithium, prepared from dimethyl(4-methoxynaphth-1-yl)silyl-
trimethylstannane (0.19 g, 0.5 mmol) and methyllithium (0.6
mL as 1.04 M Et2O solution, 0.62 mmol) in THF at -78 °C
was slowly added 2X (0.5 mmol, X ) Cl, Br, F, >99% ee) in
pentane (2.5 mL) at the designated temperature during 30
min, and the mixture was stirred for 60 min. Similar workup
as above gave the product, which gave reasonable analytical
data.
Addition of hexane (10 mL) to diastereo-9 from rac-(4-
methoxynaphth-1-yl)methylphenylsilylstananne (0.62 g, 1.41
mmol) and rac-7 (0.42 g, 1.42 mmol) at room temperature led
to the precipitation of meso-9 as a white solid (0.25 g, 0.45
mmol, 32%). Further addition of hexane (10 mL) to the residue
at 0 °C gave dl-9 as colorless solid (0.14 g, 0.26 mmol, 18%).
meso-9: 1H NMR δ 0.83 (s, 6H, (-SiCH3)2), 3.98 (s, 6H,
(-NpOCH3)2), 6.70 (d, J ) 7.8 Hz, 2H, aromatic), 7.05-7.09
(m, 2H, aromatic), 7.17-7.20 (m, 4H, aromatic), 7.28-7.37 (m,
6H, aromatic), 7.47 (s, 2H, aromatic), 7.69 (d, 2H, J ) 7.8 Hz,
aromatic), 7.71 (d, 2H, J ) 8.2 Hz, aromatic), 8.29 (d, J ) 8.2
Hz, 2H, aromatic). 13C NMR δ -2.002 (SiCH3, meso), 55.37,
103.42, 122.299, 124.73, 125.202, 125.859, 125.91, 127.62,
128.56, 129.04, 135.19, 137.103, 137.93, 138.16, 157.06. 29Si
NMR δ -20.55. Anal. Calcd for C36H34O2Si2: C, 77.93; H, 6.18.
Found: C, 77.51; H, 6.20. dl-9: Analytical data are basically
the same as those for (S,S)-9.
(R )-F lu or o(4-m e t h oxyn a p h t h -1-yl)m e t h ylp h e n ylsi-
la n e (R)-7. To a solution of (S)-(-)-[(-)-menthoxy](4-methox-
ynaphth-1yl)methylphenylsilane (>99% ee)20 (11.7 g, 27 mmol,
>99% de) in toluene (60 mL) was added freshly distilled BF3‚
Et2O (7.8 g, 55 mmol) at room temperature, and the mixture
was heated at 50 °C for 7 days. After the removal the solvent
and excess BF3‚Et2O under reduced pressure, the residue was
distilled (0.18 Torr, 130-140 °C) to give the mixture of (-)-
menthol and 7. Recrystallization of the mixture from pentane
at -78 °C gave 7 as a colorless crystal. Further recrystalliza-
tion of 7 in pentane at 0 °C for several times gave 1.16 g (>99%
ee, 13%) and 1.84 g (80% ee, 25%) of 7 as colorless crystal.
The absolute configuration was determined as the (R)-form
by the comparison of its HPLC profile with (S)- and (R)-fluoro-
(naphth-1-yl)methylphenylsilane.14a (S)-(+)-7 tR ) 90.0 min;
(R)-(-)-7 tR ) 107 min. [R ]27D ) 12.25 (c ) 0.97, cyclohexane).
1H NMR δ 0.85 (d, J ) 7.4 Hz, 3H, -SiCH3), 4.03 (s, 3H,
-NpOCH3), 6.85 (d, J ) 7.8 Hz, 1H, aromatic), 7.36-7.40 (m,
2H, aromatic), 7.42-7.50 (m, 3H, aromatic), 7.61-7.65 (m, 2H,
aromatic), 7.72 (d, J ) 7.8 Hz, 1H, aromatic), 7.94-7.98 (m,
1H, aromatic), 8.32-8.35 (m, 1H, aromatic). 13C NMR δ -1.25
(d, J ) 17.3 Hz), 55.48, 103.15, 122.62, 123.18 (d, J ) 15.4
Hz), 125.17, 125.72, 126.92, 127.83, 128.04, 130.44, 134.00,
135.35 (d, J ) 17.3 Hz), 135.74 (d, J ) 3.8 Hz), 137.72. 29Si
NMR δ 10.47 (d, J ) 280.0 Hz). Anal. Calcd for C18H17OSiF:
C, 72.94; H, 5.78. Found: C, 72.77; H, 5.824.
Clea va ge of (R)-6 by Br om in e a n d Su ccessive Red u c-
tion to (R)-1,2,2-Tr im eth yl-1-p h en yld isila n e (R)-12. Bro-
mine (1.0 mL, 0.49 M CHCl3 solution) was added dropwise to
(R)-6 (0.234 g, 0.5 mmol, (R); 95% ee) in CHCl3 (5 mL) for 10
min, and the mixture was stirred at -64 °C for 60 min.
Formation of (R)-1,2-dibromo-1,1,2-trimethyl-2-phenyldisilane
was evidenced as (R)-1,1,2-trimethyl-2-phenyldisilane (R)-1224
after the reduction with LiAlH4 (0.04 g, 1.1 mmol) in Et2O (5
mL) at 0 °C. The crude products, after the solution was
filtrated and concentrated, were separated by preparative
HPLC with hexane to afford (R)-6 (0.061 g, 68%, 84% ee). (R)-
1
(S)-(4-Meth oxyn a p h th -1-yl)m eth ylp h en ylsilyltr im eth -
ylsta n a n n e. This compound was synthesized similarly to (4-
methoxynaphth-1-yl)dimethylsilylstannnane from (R)-7 (1.0 g,
3.4 mmol, >99%ee). After evaporation of volatile materials,
hexane was added, and the mixture was vigorously stirred at
0 °C to make rac-silylstannane precipitate as a colorless
powder. After hexane was removed, the residue was purified
by column chromatography over silica gel with hexane/ethyl
acetate (80/1) as eluent (Rf ) 0.38) to give (S)-7 as a viscous
(-)-12 tR ) 13.05 min, (S)-(+)-12 tR ) 14.32 min. H NMR δ
0.20, 0.22 (two d, 6H, HSiMe2, J SiHCH ) 4.5 Hz), 0.47 (d, 3H,
PhHSiMe, J SiHCH ) 4.6 Hz), 3.87 (d septet, 1H, Me2SiH, J SiHCH
) 4.5 Hz, J SiHSiH ) 2.2 Hz), 4.32 (dq, 1H, MePhSiH, J SiHCH
)
4.6 Hz, J SiHSiH ) 2.2 Hz), 7.21-7.72 (m, 5H, aromatic). 13C
NMR δ -7.47, -6.13, 127.73, 127.81, 128.70, 134.60. EI-MS
(m/e) 180 (M+), 165 ([M - CH3]+), 135 ([M - 3CH3]+), 121
([MePhSi]+).
Clea va ge of (S,S)-9 by Br om in e. (S,S)-9 (0.277 g, 0.5
mmol, (S,S); >99% ee) at -64 °C for 20 min was similarly
treated with bromine (2.2 mL, 0.46 M CHCl3 solution). The
product was identified as reduced product, 1,2-dimethyl-1,2-
diphenyldisilane. 1H NMR δ 0.43 (d, 6H, SiMe, J CHSiH ) 4.7
Hz), 4.41 (q, 2H, SiH, J ) 4.7 Hz), 7.20-7.70 (m, 10H,
aromatic). 13C NMR δ -7.65, -7.44, 127.94, 128.98, 134.73,
134.85. EI-MS (m/e) 242 (M+), 197 ([M - 3CH3]+), 121
([MePhSi]+), 105 ([SiPh]+).
colorless oil (0.92 g, 62%, (S); >96.4% ee). [R ]27 ) -28.13 (c
D
) 1.21, cyclohexane). (R)-(+) tR ) 28.2 min, (S)-(-) tR ) 31.3
min. 1H NMR δ 0.089 (s, 9H, -Sn(CH3)3), 0.849 (s, 3H,
-SiCH3), 4.02 (s, 3H, -NpOCH3), 6.82 (d, J ) 7.8 Hz, 1H,
aromatic), 7.295-7.49 (m, 7H, aromatic), 7.579 (d, J ) 7.8 Hz,
1H, aromatic), 7.81 (d, 1H, J ) 8.2 Hz, aromatic), 8.316 (d, J
) 7.8 Hz, 1H, aromatic). 13C NMR δ -10.84, -1.49, 55.15,
103.26, 122.37, 124.69, 125.41, 125.55, 126.01, 127.703, 127.949,
128.48, 134.46, 135.16, 137.62, 138.519, 156.91. 29Si NMR δ
X-r a y Str u ctu r e Deter m in a tion of (R)-5. A single crystal
was obtained by recrystallization from hexane. Measurement
was made by Rigaku RAXIS-RAPID Imaging Plate, T ) 296
-7.19. Anal. Calcd for
Found: C, 57.11; H, 5.97.
C21H26OSiSn: C, 57.17; H, 5.94.
5388 J . Org. Chem., Vol. 69, No. 16, 2004