propellane

[[File:Propellanes.png|thumb|300px|right|Some propellanes. From left to right: [1.1.1]propellane, [2.2.2]propellane, and 1,3-dehydroadamantane (a methylene-bridged derivative of [3.3.1]propellane).]]

In organic chemistry, propellane is any member of a class of polycyclic hydrocarbons, whose carbon skeleton consists of three rings of carbon atoms sharing a common carbon–carbon covalent bond. The concept was introduced in 1966 by D. Ginsburg. Propellanes with small cycles are highly strained and unstable, and are easily turned into polymers with interesting structures, such as staffanes. Partly for these reasons, they have been the object of much research.