Cyclooctyne is the smallest cycloalkyne that is stable enough to be isolated, although the chemical is still highly reactive. The alkyne region of the structure attempts to adopt a linear molecular geometry, but the nature of the ring creates substantial ring strain. As a result, cyclooctyne and other compounds containing this ring structure readily react in ways that reduce the ring strain by converting the alkyne to a functional group that does not require linear geometry. An important application of this reactivity is in click chemistry, where cyclooctynes undergo cycloaddition reactions with azides[1] or nitrones,[2] forming triazoles or isoxazolines, respectively.
