Non-coplanar double bonds; the existence of adamantene

Abstract

On exposure to n-butyl-lithium, 1,2-di-iodoadamantane yields the highly strained bridgehead olefin adamantene, which can be intercepted in a Diels–Alder reaction with butadiene at –78 °C; in the absence of butadiene it dimerises spontaneously in a [2 + 2] fashion.