Methylenecyclopropane 1, with its highly strained ring and reactive exocyclic double bond, has long attracted interest as a synthetic intermediate, 1 and methylenecyclopropane derivatives have consequently been extensively used in synthesis, for example in [3+2] cycloaddition reactions catalysed by transition metals, 2 in radical based annulation reactions 3 and in radical cyclisation reactions. 4 A new aspect of methylene cyclopropane chemistry was recently revealed by ...