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DOI: 10.1055/s-2004-829083
Epoxydisilanes by Direct Double Silylation of Terminal Epoxides
Publikationsverlauf
Publikationsdatum:
29. Juni 2004 (online)
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Abstract
Terminal epoxides 2 are converted to epoxydisilanes 1 in a one-pot procedure in hexane at low temperatures, by using successive additions of Me3SiCl and s-BuLi-(-)-sparteine complex.
Key words
epoxides - lithiation - carbenoids - silylation - sparteine
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References
Preliminary investigations suggest LiCl aids the stability of the oxiranyl anion.
11
General Procedure for the Preparation of Epoxydisilane 1: Freshly distilled (-)-sparteine (0.3 mL, 1.3 mmol) was added dropwise to a solution of s-BuLi (1.1 mL, 1.2 M in cyclohexane, 1.3 mmol) in hexane (10 mL) at -90 °C. The mixture was allowed to warm to 0 °C over 5 min and then re-cooled to -90 °C. A solution of epoxide 2 (1 mmol) and Me3SiCl (0.16 mL, 1.3 mmol) in hexane (2 mL) was added dropwise to this mixture, whilst maintaining the internal temperature at -90 °C. After 15 min, the mixture was warmed to -50 °C over a period of 5 min. The mixture was then stirred at -50 °C for 1 h before re-cooling to -90 °C, when Me3SiCl (0.25 mL, 2 mmol) was added. s-BuLi-
(-)-sparteine complex (2 mmol) [prepared by adding
(-)-sparteine (0.46 mL, 2 mmol) dropwise to a solution of
s-BuLi (1.7 mL, 1.2 M in cyclohexane, 2 mmol) in hexane (8 mL) at -90 °C and allowing the mixture to warm to 0 °C] was then added dropwise to the reaction, whilst maintaining the internal temperature at -90 °C. After 15 min, the mixture was warmed to 0 °C over 18 h. HCl (1 N, 5 mL) was added dropwise at 0 °C and the layers were separated. The aqueous layer was washed with Et2O (3 × 5 mL) and the combined organic layers were washed with brine (5 mL), dried (MgSO4) and concentrated under reduced pressure. Purification of the residue by column chromatography (0.5% Et2O in light petroleum) gave the epoxydisilane 1 in the yields indicated in Table
[1]
. Analytical data for 1 (R = C10H21): IR (neat): 2956 (s), 2925 (s), 2854 (m), 1467 (m), 1250 (s), 1051 (s), 841 (s) cm-1. 1H NMR (400 MHz, CDCl3): δ = 3.03-2.86 (1 H, m, epoxide CH), 1.15-1.74 (18 H, m, 9 × CH2), 0.89 (3 H, t, J = 6.8 Hz, Me), 0.13 (9 H, s, SiMe3), 0.06 (9 H, s, SiMe3). 13C NMR (100 MHz, CDCl3): δ = 62.4 (CH), 51.4 (quat), 23.1, 26.8, 28.0, 29.8, 30.0, 32.0, 32.4 (9 × CH2), 14.6 (Me), 0.7 (SiMe3), -1.68 (SiMe3). MS (CI+): m/z (%) = 329 (35) [M + H+], 255 (20), 147 (20), 147 (20), 90 (100), 73 (70). Anal. Calcd for C15H31OSi2: 329.2696; found: [M + H+] 329.2698.