Automerization of an Enediyne via a Symmetrical p-Benzyne Diradical Intermediate

Abstract

Automerization is defined as a rearrangement reaction that yields a degenerate form of the starting material. We now report that cyclohexeno[3,4]cyclodeca-1,5-diyne-3-ene rearranges to its automer, via a D_2h-symmetric p-benzyne intermediate. The NMR evidence is that when the enediyne is heated to 75 °C in DMSO with either LiI or NaNO₃ as possible nucleophile, the enediyne is consumed only in the presence of LiI, whereas it remains “unchanged” in the presence of NaNO₃.