N-Allylhydrazones are reported to undergo an elaborate [3,3]-sigmatropic shift/N2 extrusion sequence. Both concerted and radical cation
pathways for the [3,3]-sigmatropic shift of several N-allylhydrazones were investigated using B3LYP/6-31+G(d,p) calculations. It was discovered
that, assuming facile formation of the N-allylhydrazone radical cation, the rearrangement takes place through a series of low barrier steps
energetically preferred to the concerted alternative available to neutral N-allylhydrazones. Subsequent N2 extrusions forming corresponding
homoallyl radicals were found to be extremely facile.