[3,3]-Sigmatropic Shifts of N-Allylhydrazones: Quantum Chemical Comparison of Concerted and Radical Cation Pathways
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.
chemical structure, energy, rearrangement, cations, extrusion
Siebert, Matthew R., and Dean J. Tantillo. "[3, 3]-Sigmatropic Shifts of N-Allylhydrazones: Quantum Chemical Comparison of Concerted and Radical Cation Pathways." Organic letters 10, no. 15 (2008): 3219-3222.