Butatrienyl Ethers, -Sulfides and -Amines

Protonation of the intermediates under carefully controlled conditions proceeds regiospecifically, giving hetero-substituted cumulenes in good yields [106]. Functionalization reactions have been carried out only with the oxygen compounds [107]. In these cases, too, the reactions are completely regiospecific. 

Successful (sp2)metallation of A N-disubstituted formamides and -thioamides with LDA was reported some ten years ago [108-111]  

The deprotonations proceed with extreme ease, even at temperatures in the region of — 100°C.Most of the reactions reported are couplings with carbonyl compounds. The species have a low thermostability, and one may wonder whether their basicity (and polarizability) is sufficiently high to warrant good yields with electrophiles that are considerably less reactive than carbonyl compounds, e.g. alkyl halides. 

---