Organolithium compounds rearrangement

Investigation (100) of 2-phenyl-2-/7-tolylpropyllithium (16) showed that this organolithium compound rearranged in ethereal solution at reflux... 

This chapter mainly concerns common rearrangements of organolithium compounds which are synthetically valuable in terms of a C—C bond or C—heteroatom bond formation. 

The regioselectivity can be better controlled if a-alkoxystannanes are used as substrates. This modification is named the Wittig-Still Rearrangement . Here, the intermediate organolithium compound is produced through transmetallation ... 

Benzyl methyl ether or allyl methyl ethers can be selectively metalated at the benzylic/allylic position by treatment with BuLi or sBuLi in THF at -40 °C to -80 C, and the resulting organolithium compounds react with primary and secondary alkyl halides, epoxides, aldehydes, or other electrophiles to yield the expected products [187, 252, 253]. With allyl ethers mixtures of a- and y-alkylated products can result [254], but transmetalation of the lithiated allyl ethers with indium yields y-metalated enol ethers, which are attacked by electrophiles at the a position (Scheme 5.29). Ethers with ft hydrogen usually undergo rapid elimination when treated with strong bases, and cannot be readily C-alkylated (last reaction, Scheme 5.29). Metalation of benzyl ethers at room temperature can also lead to metalation of the arene [255] (Section 5.3.11) or to Wittig rearrangement [256]. Epoxides have been lithiated and silylated by treatment with sBuLi at -90 °C in the presence of a diamine and a silyl chloride [257]. 

---