At high dilution and temperature adamantene undergoes a retro Diels-Alder cycloaddition to a triene, as well as retro-insertion reactions to give carbenes. 1,2-Diiodoadamantane and 3-diiodomethylnoradamantane react with methyllithium in the gas phase to give adamantene, which is efficiently reduced to adamantane under these conditions. Addition of adamantene to butadiene occurs in 4 + 2 and 2 + 2 fashion.