Isobenzofulvenes

The hitherto unknown isobenzofulvenes (benzo[c]fulvenes) are of interest as being isosteric with isobenzofuran, isobenzothiophene, and isoindole, as well as with the still hypothetical nonafulvenes (cyclononatetraenefulvenes). Like fulvene, isobenzofulvene (1) should be stabilized by electron donors on the exocyclic C atom[¹].