Attempted synthesis of a stable, quintet, tetraphenoxyl tetraradical: Facile rearrangement of a substituted bicyclobutane

The preparation of tetraphenol 3 and its attempted oxidation to tetraradical 2 are described. Tetraphenoxyl 2 was envisioned as a more stable analog of the previously reported, quintet tetraradical 1. However, EPR studies on 3 and model compounds and crystallographic characterization of the product from oxidation of 3 suggest that 2 is not a viable target. Apparently, 2 or an intermediate in the multistep oxidation path leading to it undergoes a ring closure to a bicyclobutane. The bicyclobutane, in turn, undergoes a surprisingly facile rearrangement to the analogous butadiene structure.