Generation and intramolecular cyclization of (2- ethenylphenyl)bisketenes. Synthesis of benzofuranones

Article abstract of DOI:10.1016/S0040-4039(98)00638-8

Several new differentially substituted cyclobutenediones 4a-e have been prepared. Their thermal rearrangement to substituted naphthofuranones 5a-d is reported. This rearrangement involves an unprecedented intramolecular cyclization of a reactive bisketene 6, and forms the naphthofuranone system in good yield.