Unusual Skeletal Editing of Oxadiazinones with Aryne Intermediates

An unusual skeletal editing method involving a 6-to-8 ring expansion of oxadiazinones with aryne intermediates is disclosed. The construction of a new skeleton from oxadiazinones was confirmed by 1H and 13C NMR spectroscopy and X-ray crystallographic analysis. We found that the use of tetrabutylammonium difluorotriphenylsilicate as the activator provides access to a ring-expansion pathway distinct from the conventional Diels–Alder/denitrogenation sequence.