Ring Opening of Methylenecycloalkenes via the C−C Bond Cleavage

3-Methylenecycloalkene-1,1-dicarboxylates underwent facile ring opening via the cleavage of the unactivated C−C bond to yield aliphatic alkenes. The reaction (intramolecular deallylation) was catalyzed by “Ni−H” species generated in situ from a NiX₂(phosphine)_n/R₃Al mixture and proceeded under ambient conditions. In addition, the skeletal rearrangement of a diene could be carried out by a one-pot cycloisomerization/deallylation sequence.