Letters

Studies in the cycloproparene series; heterocyclic substituted methylidenecyclopropa[b]naphthalenes

“…2 . 1 3 Although rocketene 4 l4 and its angular isomer 5 l 5 are comparatively easy to prepare, neither of the two possible dicyclopropabenzenes are known.' In comparison, the fusion of a three-membered ring to separate rings of naphthalene,I6 anthracene and phenanthrene, and derivatives '' has been achieved, and triscycloproparenes which have three cyclopropabenzenoid moieties have now been reported18 (Fig.…”