Epoxydisilanes by Direct Double Silylation of Terminal Epoxides

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

References

• 1 Hodgson DM. Comina PJ. Drew MGB. J. Chem. Soc., Perkin Trans. 1  1997,  2279 
• 2a Page PCB. McKenzie MJ. In Science of Synthesis: Houben-Weyl Methods of Molecular Transformations   Vol. 4:  Fleming I. Thieme; Stuttgart: 2001.  p.513 
• 2b Mattson AE. Bharadwaj AR. Scheidt KA. J. Am. Chem. Soc.  2004,  126:  2314 
• 2c Linghu X. Potnick JR. Johnson JS. J. Am. Chem. Soc.  2004,  126:  3070 
• 3a Hodgson DM. Norsikian SLM. Org. Lett.  2001,  3:  461 
• 3b See also: Hodgson DM. Reynolds NJ. Coote SJ. Tetrahedron Lett.  2002,  43:  7895 
• 4a Eisch JJ. Galle JE. J. Am. Chem. Soc.  1976,  98:  4646 
• 4b Burford C. Cooke F. Roy G. Magnus P. Tetrahedron  1983,  39:  867 
• 4c Eisch JJ. Galle JE. J. Organomet. Chem.  1988,  341:  293 
• 4d Hudrlick PF. Hudrlick AM. In Advances in Silicon Chemistry   Vol. 2:  Larson GL. JAI Press Inc.; Greenwich: 1993.  p.1 
• 4e Courillon C. Marié J.-C. Malacria M. Tetrahedron  2003,  59:  9759 
• 5 Under these reaction conditions, other diamine ligands (N,N-dibutyl-3,7-diazabicyclo[3.3.1]nonane or TMEDA) or Et₂O as solvent were less effective in generating the desired epoxydisilane 1
• 6a Ukaji Y. Yoshida A. Fujisawa T. Chem. Lett.  1990,  157 
• 6b Agami C. Dechoux L. Doris E. Mioskowski C. Tetrahedron Lett.  1997,  38:  4071 
• For reviews, see:
• 7a Doris E. Dechoux L. Mioskowski C. Synlett  1998,  337 
• 7b Hodgson DM. Gras E. Synthesis  2002,  1625 
• 8 Molander GA. Mautner K. J. Org. Chem.  1989,  54:  4042 
• Epoxides in Table 1 were commercially available or prepared according to:
• 10a Elings JA. Downing RS. Sheldon RA. Eur. J. Org. Chem.  1999,  837 ; entry 3
• 10b Rothberg I. Schneider L. Kirsch S. OFee R. J. Org. Chem.  1982,  47:  2675 ; entry 4
• 10c Yang L. Weber AE. Greenlee WJ. Patchett AA. Tetrahedron Lett.  1993,  34:  7035 ; entry 5

9

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.