Organometallics
Article
eluent, n-pentane/ethyl acetate (10/1 v/v)). The relevant fractions
(GC analysis) were combined, and the solvents were removed under
reduced pressure. The residue was crystallized from n-pentane (20
mL) at −20 °C, and the product was isolated by filtration and dried in
vacuo (0.001 mbar, 20 °C, 4 h) to give 17 in 56% yield as a colorless
crystalline solid (2.84 g, 6.11 mmol); mp 79−81 °C. 1H NMR (500.1
MHz, C6D6): δ 0.32 (s, 9 H; Si(CH3)3), 1.00 (s, 2 H; SiCH2Si), 1.20
(s, 3 H; SiCH3), 3.43 (s, 12 H; o-OCH3, C6H2(OCH3)3), 3.50 (s, 6 H;
liquid (1.51 g, 2.22 mmol). 1H NMR (500.1 MHz, C6D6): δ 0.00 (s, 4
H; Si(CH2SiCH2Si)2), 0.32 (s, 18 H; Si(CH3)2(CH2Si-
(CH3)2CH2Si)2), 0.46 (s, 4 H; Si(CH2SiCH2Si)2), 0.79 (s, 12 H;
Si(CH2Si(CH3)2CH2Si(CH3)2)2), 3.46 (s, 12 H; o-OCH3,
C6H2(OCH3)3), 3.50 (s, 6 H; p-OCH3, C6H2(OCH3)3), 6.17 (s, 4
H; H-3/H-5, C6H2(OCH3)3). 13C NMR (125.8 MHz, C6D6): δ 2.7
(Si(CH2Si(CH3)2CH2Si)2), 2.9 (Si(CH3)2(CH2SiCH2Si)2), 3.9 (Si-
(CH2SiCH2Si(CH3)2)2), 6.5 (SiCH2SiCH2Si), 7.4 (SiCH2SiCH2Si),
54.6 (o-OCH3, C6H2(OCH3)3), 54.7 (p-OCH3, C6H2(OCH3)3), 90.7
(C-3/C-5, C6H2(OCH3)3), 106.5 (C-1, C6H2(OCH3)3), 163.7 (C-4,
C6H2(OCH3)3), 166.6 (C-2/C-6, C6H2(OCH3)3). 29Si NMR (99.4
MHz, C6D6): δ −6.9 (Si(CH2SiCH2Si)2), 0.2 (Si(CH2SiCH2Si)2), 0.5
(Si(CH2SiCH2Si)2). Anal. Calcd for C32H60O6Si5: C, 56.42; H, 8.88.
Found: C, 56.3; H, 9.2.
Crystal Structure Analyses. Suitable single crystals of 1, 2, 12−
15, 17, and 18 were obtained by crystallization from diethyl ether at
−20 °C (1, 2, 12, 13) or from n-pentane at −20 °C (14, 15, 17, 18).
The crystals were mounted in inert oil (perfluoropolyalkyl ether,
ABCR) on a glass fiber and then transferred to the cold nitrogen gas
stream of the diffractometer (1, 2, 12, 15, 17, 18, Stoe IPDS, graphite-
monochromated Mo Kα radiation (λ = 0.71073 Å); 13, 14, Bruker
Nonius KAPPA APEX II, Montel mirror, Mo Kα radiation (λ =
0.71073 Å)). The structures were solved by direct methods (SHELXS-
97).12 All non-hydrogen atoms were refined anisotropically (SHELXL-
97).12 A riding model was employed in the refinement of the CH
hydrogen atoms. CCDC-928119 (1), CCDC-928120 (2), CCDC-
928121 (12), CCDC-928122 (13), CCDC-928123 (14), CCDC-
928124 (15), CCDC-928125 (17), and CCDC-928126 (18) contain
supplementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic Data
p-OCH3, C6H2(OCH3)3), 6.20 (s, 4 H; H-3/H-5, C6H2(OCH3)3). 13
C
NMR (125.8 MHz, C6D6): δ 1.8 (Si(CH3)3), 4.6 (SiCH3), 5.5
(SiCH2Si), 54.6 (p-OCH3, C6H2(OCH3)3), 54.9 (o-OCH3,
C6H2(OCH3)3), 91.1 (C-3/C-5, C6H2(OCH3)3), 109.7 (C-1,
C6H2(OCH3)3), 162.9 (C-4, C6H2(OCH3)3), 166.3 (C-2/C-6,
C6H2(OCH3)3). 29Si NMR (99.4 MHz, C6D6): δ −14.4 (SiCH3),
0.1 (Si(CH3)3). Anal. Calcd for C23H36O6Si2: C, 59.45; H, 7.81.
Found: C, 59.5; H, 7.8.
Preparation of Bis[[dimethyl(2,4,6-trimethoxyphenyl)silyl]-
methyl]dimethylsilane (18). Naphthalene (4.58 g, 35.7 mmol) was
added in a single portion at 20 °C to a stirred suspension of lithium
powder (248 mg, 35.7 mmol) in THF (20 mL), and the mixture was
stirred at this temperature for 16 h. The resulting dark-green
suspension was cooled to −30 °C, and a solution of 1 (4.68 g, 17.0
mmol) in THF (6 mL) was added dropwise at this temperature within
10 min. The reaction mixture was stirred at −30 °C for a further 2 h,
and then dichlorodimethylsilane (1.10 g, 8.52 mmol) was added in a
single portion at this temperature. After it was stirred at −30 °C for 1
h, the mixture was warmed to 20 °C, followed by sequential addition
of diethyl ether (60 mL) and water (60 mL). The organic layer was
separated and washed with water (3 × 30 mL), and the combined
aqueous layers were extracted with diethyl ether (3 × 30 mL) and
discarded. The combined organic extracts were dried over anhydrous
sodium sulfate, the solvent was removed under reduced pressure, and
the residue was purified by bulb-to-bulb distillation (160 °C/0.01
mbar; removal of byproducts), followed by recrystallization of the
remaining solid residue from n-pentane (15 mL) to give 18 in 78%
yield as a colorless crystalline solid (3.57 g, 6.65 mmol); mp 68−70
°C. 1H NMR (500.1 MHz, C6D6): δ 0.29 (s, 6 H; Si(CH3)2), 0.48 (s,
4 H; SiCH2Si), 0.78 (s, 12 H; Si(CH2Si(CH3)2)2), 3.44 (s, 12 H; o-
OCH3, C6H2(OCH3)3), 3.49 (s, 6 H; p-OCH3, C6H2(OCH3)3), 6.16
(s, 4 H; H-3/H-5, C6H2(OCH3)3). 13C NMR (125.8 MHz, C6D6): δ
2.2 (Si(CH3)2), 3.8 (Si(CH2Si(CH3)2)2), 6.4 (SiCH2Si), 54.5 (o-
OCH3, C6H2(OCH3)3), 54.6 (p-OCH3, C6H2(OCH3)3), 90.7 (C-3/C-
5, C6H2(OCH3)3), 106.9 (C-1, C6H2(OCH3)3), 163.6 (C-4,
C6H2(OCH3)3), 166.6 (C-2/C-6, C6H2(OCH3)3). 29Si NMR (99.4
MHz, C6D6): δ −6.8 (Si(CH2Si)2), 0.8 (Si(CH2Si)2). Anal. Calcd for
C26H44O6Si3: C, 58.17; H, 8.26. Found: C, 58.0; H, 8.4.
ASSOCIATED CONTENT
* Supporting Information
■
S
Crystallographic data for compounds 1, 2, 12−15, 17, and 18
(Tables S1 and S2 and CIF files). This material is available free
AUTHOR INFORMATION
Corresponding Author
■
Notes
The authors declare no competing financial interest.
Preparation of Bis[[[[dimethyl(2,4,6-trimethoxyphenyl)silyl]-
methyl]dimethylsilyl]methyl]dimethylsilane (19). Naphthalene
(1.92 g, 15.0 mmol) was added in a single portion at 20 °C to a stirred
suspension of lithium powder (104 mg, 15.0 mmol) in THF (10 mL),
and the mixture was stirred at this temperature for 17 h. The resulting
dark-green suspension was cooled to −30 °C, and a solution of 1 (2.00
g, 7.28 mmol) in THF (5 mL) was added dropwise at this temperature
within 2 min. The reaction mixture was stirred at −30 °C for a further
1 h, and then 10 (995 mg, 3.64 mmol) was added in a single portion at
this temperature. After it was stirred at −30 °C for 1 h, the mixture
was warmed to 20 °C, followed by sequential addition of diethyl ether
(50 mL) and water (50 mL). The organic layer was separated and
washed with water (3 × 20 mL), and the combined aqueous layers
were extracted with diethyl ether (3 × 20 mL) and discarded. The
combined organic extracts were dried over anhydrous sodium sulfate,
the solvent was removed under reduced pressure, and the residue was
purified by bulb-to-bulb distillation (220 °C/0.3 mbar; removal of
byproducts), followed by further purification of the remaining residue
by column chromatography on silica gel (40−63 μm, 140 g (Merck);
treated with concentrated aqueous ammonia solution (7% by weight
related to the silica gel); n-pentane/ethyl acetate (10/1 v/v)). The
relevant fractions (GC analysis) were combined, the solvents were
removed under reduced pressure, and the residue was dried in vacuo
(0.01 mbar, 20 °C, 5 h) to give 19 in 61% yield as a colorless viscous
REFERENCES
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dx.doi.org/10.1021/om400190q | Organometallics XXXX, XXX, XXX−XXX