Vinylidene to alkyne rearrangement to form polyynes: synthesis and photolysis of dialkynylmethylenebicyclo[4.3.1]deca-1,3,5-triene derivatives

Dialkynylmethylenebicyclo[4.3.1]deca-1,3,5-triene derivatives were synthesized as precursors to generate dialkynylvinylidenes by extrusion of an aromatic fragment, indane. Photolysis of the trienes gave linear polyynes as the major products produced by rearrangement of the vinylidenes, together with the isomerization products having a methylenecycloheptatriene moiety.