Metallation reactions. Part XV. Metallation of diacetylenes

Hexa-2,4-diyne was metallated with butyl-lithium and methyl-lithium smoothly to the trilithio-derivative by abstraction of three protons from the same carbon. Prolonged metallation with butyl-lithium led to the tetralithiocompound. A trilithio-derivative was also obtained from octa-2,4-diyne, but octa-3,5-diyne yielded a dilithioderivative. The two triple bonds of hepta-1,6-diyne were metallated independently to give di-, tri- and tetralithio-derivatives. A 1 Hz coupling constant through seven bonds was observed in the monolithiohexadiyne.