ChemInform Abstract: Polylithiumorganic Compounds. Part 6. cis- and trans-1,2-Dilithioethylene.
Abstract
The lithiation of (Ia) or (Ib) to give (Va) or (Vb) can be carried out by means of a metal exchange in order to avoid steric hindrance at a fivefold coordinated Sn.
ChemInform Abstract
The lithiation of (Ia) or (Ib) to give (Va) or (Vb) can be carried out by means of a metal exchange in order to avoid steric hindrance at a fivefold coordinated Sn. The increase of the (VIIa)/(VIIb) ratio in the reaction mixture of the isomers (IIIa) and (IIIb) is brought about by the preferential HLi elimination from (Vb) ( → CH≡C-Li → CH2-Li + Li-C≡C-Li) compared with (Va) to yield (IX) and (VIII) by methylation with (VI).