Science of Synthesis

Sarkar, T. K., Science of Synthesis, (2002) 4, 853.

Allylsilanes are available from aldehydes and ketones by reaction with a metalated sulfone, generated from trimethyl[2-(phenylsulfonyl)ethyl]silane (‌54‌) and butyllithium, followed by mesylation of the resultant alcohol, and reductive elimination of the crude methanesulfonate with 6% sodium amalgam. This method is used for the preparation of allylsilanes ‌55‌ (‌Scheme 25‌).[‌109‌,‌110‌] Sulfone ‌54‌ is available from trimethyl(vinyl)silane by radical-catalyzed addition of benzenethiol, followed by oxidation. The formation of ‌55‌ [R1,R2 = (CH2)3; R1 = R2 = Ph] indicates that the presence of strain or steric hindrance in carbonyl groups does not seriously impede reaction of the metalated sulfone.[‌110‌] Moreover, the method works for the preparation of (2-cyclopentylideneethyl)trimethylsilane [‌55‌, R1,R2 = (CH2)4], where Wittig alkenation fails, but, like the Wittig reaction, lacks stereoselectivity, as is the case for the preparation of silane ‌55‌ (R1 = H; R2 = Ph) (see also Section ‌4.4.40.9‌). It has been suggested that 1,2-dimethoxyethane may be the solvent of choice for addition of metalated sulfone derived from ‌54‌ to enolizable aldehydes.[‌111‌]

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References

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• 8.Meeeee-Meee, (8888) M 88e, 8888.