1,3-Dehydroadamantane
1,3-Dehydroadamantane, formally tetracyclo[3.3.1.1.0]decane, is an organic compound with formula CH, which can be obtained from adamantane by removal of two hydrogen atoms to create an internal bond. It is a polycyclic hydrocarbon, and can be viewed also as being derived from [3.3.1]propellane by addition of a methylene bridge between the two larger rings. Like other small-ring propellanes, this compound is substantially strained and unstable. Synthesis. 1,3-Dehydroadamantane was obtained in 1969 by Richard Pincock and Edward Torupka, by reduction of 1,3-dibromoadamantane according to the scheme below: Reactions. Oxidation. On standing in solution, it reacts with  oxygen from air (with a half-life of 6 hours), yielding a peroxide. The latter converts to a dihydroxide by reaction with lithium aluminium hydride. Polymerization. Like [1.1.1]propellane, 1,3-dehydroadamantane can be polymerized by breaking the axial bond and joining the resulting radicals into a linear chain: In this scheme, 1,3-dehydroadamantane is reacted with acrylonitrile in a radical polymerization initiated with lithium metal in tetrahydrofuran. The resulting alternating copolymer has a glass transition temperature of 217 °C