Lithiation of Allyl Trimethylsilane with BuLi TMEDA

3 Lithiation of Allyl Trimethylsilane with BuLi TMEDA 

Me3SiCH(Li)CH=CH2 + C4H10 Functionalization with trimethylchlorosilane and cyclohexanone. 

In order to achieve metallation of allyl trimethylsilane, Schaumann, Chan, and coworkers [1,2] use the strongly basic systems sec-BuLi-TMEDA-THF, n- 

BuLi TMEDA or HMPT-THF and t-BuLi TMEDA or HMPT THF. Magnus et al. reported [3] that complete lithiation is effected by BuLi (presumably n-BuLi) in THF at — 40 °C (no reaction time is mentioned). We found that under these conditions no conversion takes place, but observed a very smooth reaction when using the BuLi-TMEDA combination in hexane at 20 to 30 °C. 

This experiment describes the lithiation of allyl trimethylsilane and the conversions of the lithio compound with trimethylchlorosilane and cyclohexanone, reactions that proceed with very high y-selectivity. For functionalizations with other electrophiles, e.g., epoxides, alkyl halides, and carbon dioxide, see Ref. [1] and literature cited in this paper. 

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