NEW ROUTES TO 5,8,8-TRIPHENYLBENZOHEPTAFULVENES FROM (3,4-BIS(DIPHENYLMETHYLENE)-2-OXOCYCLOBUTYLIDENE)TRIPHENYLPHOSPHORANE. ISOLATION OF EXCESSIVELY STABILIZED BETAINE.

Article abstract of DOI:10.1016/0040-4039(80)80162-6

Thermal isomerization of HBr salt of the title phosphorane gave (2-hydroxy-5,8,8-triphenylbenzoheptafulvenyl)triphenylphophonium bromide, which upon dehydrobromination afforded excessively stabilized betaine.Thermal reaction of the title phosphorane with diphenylketene gave 5,8,8-triphenyl-benzoheptafulvene which is condensed with cyclopropane ring.