Rearrangements triple bond participation with

When two equivalents of pyridine were added to the nmr sample and the probe heated to 80° C, the enol formate 61 decreased and phenyl cyclopropyl ketone 58 appeared at a rate approximately ten times faster than in the previous buffered system. The observation of intermediate 61 and the kinetic results, together with the observed induction periods, are consistent with the idea that some and perhaps all of the rearranged product ketone in the solvolysis of this system arises via double-bond participation in 61 rather than triple-bond participation and a vinyl cation (80). 

Despite the typical use of the 1,5-dienic system in the hetero-Cope rearrangement the participation of triple bonds, C=N and C=C, in the [3,3]-sigmatropic rearrangement was also reported. Synthesis of A-substituted benzimidazolinones 175 by a hetero-Cope rearrangement of the adduct 174 formed by reaction of A-arylhydroxamic acids 172 with cyanogen bromide 173 in the presence of triethylamine and at low temperatures was reported by Almeida, Lobo and Prabhakar (equation 51). 

---