Fluorine on fluorenes.

A practical synthesis of 1,8-difluorofluorenone and of its (2,7)-dibromo and (2,4,5,7)-tetrabromo derivatives has been developed. Fluorinated fluorenones are the starting materials for polyhalogenated dibenzochrysenes as well as for geodesic hydrocarbons. 2,7-Dibromo-1,8-difluoro-9-fluoren-9-one was converted to 3,14-dibromo-4,13-difluorodibenzo[,]chrysene through a novel strategy.