Formation of organodilithium compounds via lithium-tin exchange

Article abstract of DOI:10.1021/om00053a054

The reaction of methyllithium in THF with 2,5-bis(trimethylstannyl)-1,5-hexadiene (6) affords 2,5-dilithio-1,5-hexadiene (2) via the intermediacy of lithium stannates. The similar reaction of (2Z,4Z)-2,5-bis(trimethylstannyl)-2,4-hexadiene (11) affords (2E,4E)-2,5-dilithio-2,4-hexadiene (3). The more favorable formation of 3 suggests a greater relative stability over 2. Ab initio calculations indicate that the symmetrical dilithium-bridged structure found for 3 is more favorable than the unsymmetrical dilithium-bridged structure found for 2.